Rozprawy doktorskie na temat „LDLrKO”

Selon l’Organisation Mondiale de la Santé (OMS), les maladies cardiovasculaires (MCV) représentent la première cause de mortalité dans le monde. La prévalence augmentée de la maladie hépatique stéatosique associée à un dysfonctionnement métabolique (MASLD) et sa relation étroite avec le syndrome métabolique laissent suggérer un rôle du foie dans le développement de ces MCV. Cependant, le lien entre MASLD et MCV reste encore peu clair. Dans ce contexte, grâce à l’utilisation d’un modèle murin adapté et de différents outils moléculaires développés au laboratoire, j’ai pu réaliser mes travaux de thèse sur l’exploration du lien entre, d’une part le foie et la MASLD et, d’autre part le développement de l’athérosclérose à l’origine de ces MCV. De plus, le récepteur nucléaire PPARα a été employé comme outil de modulation de la MASLD. Le premier objectif de ma thèse était d’évaluer l’implication du foie dans les effets athéroprotecteurs du pemafibrate, un nouvel agoniste puissant et sélectif de PPARα. Pour cela, nous avons utilisé le modèle de souris double déficient pour le récepteur aux LDL (Ldlr-/-) et pour PPARα, dans lequel l’expression du PPARα sauvage ou d’un mutant de PPARα (exerçant seulement l’activité de transrépression) a été restaurée uniquement dans les hépatocytes de souris grâce à des vecteurs adeno-associated virus (AAV) adaptés. Ces souris ont été soumises à un régime western supplémenté ou non avec le pemafibrate pendant 8 semaines. Les résultats de cette étude montrent que l’activité transrépressive du PPARα hépatocytaire associée aux effets anti-inflammatoires du PPARα dans la MASLD est essentielle et suffisante pour induire les effets athéroprotecteurs du pemafibrate. Le deuxième objectif de ma thèse était de développer un nouveau modèle de souris associant un développement progressif de MASLD et d’athérosclérose dans un contexte cardiométabolique mimant la pathologie humaine. Pour cela, des souris Ldlr-/-, à la fois mâles et femelles, et déficientes ou non en PPARα, ont été soumises à un régime chow ou à un régime enrichi en graisses et en cholestérol. Une cinétique d’évolution de la MASLD et de l’athérosclérose a été réalisée. Les résultats de cette étude montrent un développement progressif à la fois de la MASLD avec toutes les caractéristiques de la pathologie humaine (stéatose, inflammation, ballooning, fibrose) et de l’athérosclérose, dans un contexte pouvant associer obésité et insulinorésistance. De manière intéressante, des spécificités histologiques et métaboliques associées au genre et à la déficience en PPARα ont été observées. Ainsi, les résultats obtenus au cours de ma thèse ont permis de montrer l’importance du foie, et plus particulièrement de l’inflammation hépatique, dans le développement de l’athérosclérose. Le nouveau modèle murin de MASLD et d’athérosclérose permettra de mieux comprendre les mécanismes physiopathologiques mis en jeu dans la MASLD ainsi que les risques cardiovasculaires associés à cette pathologie
According to the World Health Organization (WHO), cardiovascular diseases (CVD) are the leading cause of death in the world. The increased prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) and its strong association with metabolic syndrome suggest a role of the liver in the development of CVD. However, the link between MASLD and CVD remains poorly understood. In this context, using an appropriate mouse model and various molecular tools developed in the laboratory, my thesis work explored the link between the liver and MASLD on one hand, and the development of atherosclerosis which leads to CVD, on the other. In addition, the nuclear receptor PPARα was used as a tool to modulate MASLD. The first aim of my thesis was to evaluate the involvement of liver in the atheroprotective effects of pemafibrate, a potent and selective PPARα agonist. To do this, we used a double-knockout mouse model, deficient in both LDL receptor (Ldlr-/-) and PPARα, and restored the expression of wild-type PPARα or a PPARα mutant (exerting only transrepressive activity) specifically in hepatocytes using adeno-associated virus (AAV) vectors. These mice were subjected to a western diet, with or without pemafibrate supplementation, for 8 weeks. The results of this study demonstrated that the transrepressive activity of hepatocyte PPARα, associated with its anti-inflammatory properties, is essential and sufficient to induce the atheroprotective effects of pemafibrate. The second objective of my thesis was to develop a new mouse model able of simultaneously developing progressive MASLD and atherosclerosis in a cardiometabolic context that mimics human pathology. To do this, male and female Ldlr-/- mice expressing (Pparα+/+) or lacking (Pparα-/-) PPARα were fed either a chow diet or a diet enriched in fat and cholesterol. Kinetics of MASLD and atherosclerosis progression were established. The results of this study revealed the progressive development of both MASLD, with all the human characteristics (namely steatosis, inflammation, ballooning and fibrosis), and atherosclerosis in a context that may combine obesity and insulin resistance. Interestingly, histological and metabolic features associated with sex and PPARα-deficiency were observed. In conclusion, the results obtained during my thesis demonstrate the importance of the liver, and more specifically of hepatic inflammation, in the development of atherosclerosis. The new mouse model of MASLD and atherosclerosis will help to better understand the pathophysiological mechanisms involved in MASLD and the cardiovascular risks associated with this pathology

Orientador: Marta Helena Krieger
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: O objetivo deste trabalho foi avaliar a biodisponibilidade do óxido nítrico (NOo) nas disfunções cardiovasculares, especificamente na hipertrofia ventricular esquerda e na aterosclerose. Para tanto, realizamos dois estudos em camundongos deficientes do receptor de LDL (LDLr-/-): o primeiro realizado em continuidade aos estudos desenvolvidos anteriormente em nosso grupo de pesquisa, os quais demonstraram a ação do doador de NOo na prevenção da hipertrofia ventricular esquerda e na proteção contra arritmia via indução do acoplamento adrenoceptor-beta2 (ß2AR) à proteína G inibitória (Gi); e no segundo estudo, foi avaliada a biodisponibilidade de NOo na fase inicial da aterogênese, com objetivo de caracterizar as alterações sistêmicas e locais. No primeiro estudo mostramos que o doador de NOo, S-Nitroso-N-acetilcisteína (SNAC) administrado, promoveu ação cardioprotetora contra o remodelamento cardíaco via redução do estresse oxidativo e apoptose celular, os quais foram determinados pelas medidas ventriculares da produção de superóxido (O-o2) e peróxido de hidrogênio (H2O2) e pelo índice de morte celular por apoptose. Esta ação cardioprotetora foi vista no aumento da expressão e no conteúdo de S-nitrosação do ß2AR. Estes efeitos foram associados à cardioproteção contra a arritmia via indução do acoplamento ß2AR à Gi. O objetivo do segundo estudo foi avaliar a biodisponibilidade de NOo na fase inicial da aterogênese em camundongos LDLr-/- no curso temporal de 15 a 60 dias de dieta, com a quantificação de parâmetros sistêmicos representados pela pressão arterial, perfil lipidêmico e ateroma, bem como de parâmetros locais representados pela atividade e expressão da via NO/NOS e suas modificações póstraducionais no processo inflamatório via CD40-CD40L. Camundongos LDLr-/-submetidos à dieta rica em gordura apresentaram progressão do tamanho do ateroma no curso temporal analisado, contudo não foi associado a similares incrementos nos níveis de dislipidemia. Não foram detectadas alterações na pressão arterial do fenótipo hipertenso deste animal. Contudo, localmente foi verificado incremento na atividade da eNOS via fosforilação de resíduos de serina 1179 (S1179) em 30 dias de dieta rica em gordura, que pode ser considerado um mecanismo emergencial à aterosclerose . Posteriormente, com a evolução do ateroma (60 dias) houve redução desta ativação, bem como do conteúdo de proteínas S-nitrosadas. O desenvolvimento de ateroma em 30 e 60 dias induzido pela dieta mostrou aumento da atividade inflamatória por meio da denitrosação de tióis críticos da via CD40. Portanto, a análise das alterações no curso temporal apresentou somente mudanças locais como alteração na biodisponibilidade de NOo, ativação inflamatória via denitrosação do receptor CD40 e redução do conteúdo de S-nitrosação total, enquanto as alterações sistêmicas neste período de tempo ainda não são evidentes
Abstract: The objective of this study was to evaluate the bioavailability of nitric oxide (NOo) in cardiovascular disorders, specifically on the left ventricular hypertrophy and atherosclerosis. Therefore, we performed two studies with LDL receptor-deficient mice (LDLr-/-): the first one was performed in sequence to the studies previously developed in our research group, which showed the NOo donor action on the prevention of left ventricular hypertrophy and protection against arrhythmia via induction of the coupling from beta adrenoceptor-2 (ß2AR) to the inhibitory G protein (Gi); and the second study,it was evaluated the bioavailability of NOo to characterize the systemic and local alterations in the early stages of atherogenesis. The first study showed that the administration of NOo donor S-Nitroso-N-Acetylcysteine (SNAC) promoted cardioprotective action by blocked the cardiac remodeling through reduction of oxidative stress and of apoptosis, which were determined by measures of ventricular superoxide (O-o2) and hydrogen peroxide (H2O2) production and the cell death index, respectively. This cardiprotective action was charactherized by the increase of expression and content of S-nitrosation of ß2AR. These effects were associated with cardioprotection against arrhythimia via induction of ß2AR coupling Gi. The objective of the second study was to evaluate the bioavailability of NOo in the LDLr-/- mice early atherogenesis in LDLr-/ - mice from 15 to 60 days, with the quantification of systemic parameters represented by the blood pressure, lipidemic profile and atheroma as well as local ones represented by the activity and expression of NO/NOS pathway and its post-translational modifications on the inflammatory process via CD40- CD40L. Mice LDLr-/ - maintained on high-fat diet showed progression of atheroma size, although it was not associated with similar increase in dyslipidemic profile. No changes in blood pressure were detected in the hypertensive phenotype of this animal. However, increased activity of eNOS via phosphorylation of Ser1179 (S1179) at 30 days of high-fat diet was detected and it can be considered an emergential mechanism to early atherosclerosis. The development of atheroma (60 days) blocked that activation as well as the protein content of S-nitrosated. The atheroma induced at 30 and 60 days by high-fat diet revealed increase inflammatory activity through denitrosation of critical thiols via CD40. Therefore, the analysis of changes in this time course showed only local changes as changes on NOo bioavailability alteration inflammatory activation via denitrosation of CD40 receptor and the content of total S-nitrosation reduction. However, systemic changes in this period of time have not been evident yet
Doutorado
Fisiologia
Doutor em Biologia Funcional e Molecular

The discovery that proprotein convertase subtilisin/kexin type 9 (PCSK9) mediates degradation of low-density lipoprotein receptors (LDLR) indicates a critical role in LDL metabolism. PCSK9 is a secreted protein that binds to the epidermal growth factor-like (EGF)-A domain of LDLR and directs the receptor for degradation in lysosomes by an unknown mechanism. A gain-of-function mutation, D374Y, increases binding to LDLR EGF-A >10-fold and is associated with a severe form of hypercholesterolemia in humans. Similar to previous studies, data obtained in my project has established that PCSK9 was capable of promoting robust LDLR degradation in liver-derived cell lines; however, minimal effects on LDLR levels were detected in several lines of fibroblast cells despite normal LDLR-dependent cellular uptake of PCSK9. Importantly, a PCSK9 degradation assay showed that 125I-labeled wild-type PCSK9 was internalized and degraded equally in both hepatic and fibroblast cells, indicating dissociation of wild-type PCSK9 from recycling LDLRs in fibroblasts. Moreover, PCSK9 recycling assays confirmed that no recycling of wild-type PCSK9 to the cell surface could be detected in fibroblast cells. In contrast, more than 60% of internalized PCSK9-D374Y recycled to the cell surface in these cells, and thus had reduced ability to direct the LDLR for lysosomal degradation despite persistent binding. Co-localization studies indicated that PCSK9-D374Y trafficked to both lysosomes and recycling compartments in fibroblast cells, whereas wild-type PCSK9 exclusively trafficked to lysosomes. We conclude that two factors diminish PCSK9 activity in fibroblast cells: i) an increased dissociation from the LDLR in early endosomal compartments, and ii) a decreased ability of bound PCSK9 to direct the LDLR to lysosomes for degradation. Finally, an LDLR variant that binds to PCSK9 in a Ca2+-independent manner could partially restore wild-type PCSK9 activity, but not PCSK9-D374Y activity, in fibroblast cells.

Orientador: Marta Helena Krieger
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A incidência de riscos de doença aterosclerótica cardiovascular é maior em homens do que em mulheres na fase reprodutiva, essa diferença diminui quando diminui a produção de estrógenos após a menopausa. Uma série de estudos sugere que essa diferença em ambos os sexos pode ser causada em parte, pela ação pró-aterogênica dos andrógenos. O objetivo deste estudo foi verificar a participação do dimorfismo sexual em camundongos adultos LDLr-/- no efeito vasculoprotetor promovido pelo tratamento com a S-nitrosotiol-N-acetilcisteína (SNAC) na fase inicial da aterogênese por meio dos seguintes avaliações : a) expressão fenotípica da hipertensão; b) desenvolvimento de ateroma; c) perfil lipídico; d) imunorreatividade das isoformas das NOS vasculares. Camundongos machos e fêmeas com 3 meses de idade foram avaliados nos seguintes grupos experimentais: selvagens C57BL/6 (WT) sob dieta comercial; LDLr-/- sob dieta comercial com os controles (CT);LDLr-/-sob dieta hipercolesterolêmica (HC); LDLr-/- sob diet hiperlipidêmica associado ao tratamento com SNAC 0,51µm ip/dia ( HC+SNAC). Após 2 semanas de tratamento com administração de dieta hipercolesterolêmica, verificou-se que as fêmeas desenvolveram lesões ateroscleróticas na aorta proximal ascendente 50% menores em relação aos machos. Tais evidências sugerem o papel protetor do estrógeno presente nas fêmeas adultas no estágio inicial da aterosclerose. O tratamento com SNAC promoveu a redução em 50% na instalação do ateroma em ambos sexos, evidenciando não haver relação com o dimorfismo sexual. Contudo, o perfil lipídico das fêmeas mostrou valores mais elevados que os encontrados em machos, tanto de colesterol (COL), como de triglicérides (TG) plasmáticos nos camundongos sob dieta hipercolesterolêmica. Assim, o tratamento com SNAC não impediu o aumento dos teores lipidêmicos induzidos pela dieta hipercolesterolêmica em fêmeas, inferindo que a condição não está correlacionada ao tamanho da área de lesão desenvolvida. Camundongos fêmeas LDLr-/- sob dieta aterogênica evidenciaram aumento de cerca de 10% na pressão arterial, quando comparados aos respectivos camundongos selvagens (WT). O tratamento com SNAC preveniu totalmente a hipertensão induzida pela dieta hipercolesterolêmica. Contudo, nos machos tal hipertensão foi verificada ocorrer em camundongos LDLr-/- sem dieta hipercolesterolêmica, e o tratamento com SNAC não produziu efeito preventivo na hipertensão. Tais resultados indicam que a gênese da hipertensão é diferente nos dois sexos, sugerindo a participação das vias androgênicas. As fêmeas não apresentaram hipertrofia ventricular esquerda ou redução na frequência cardíaca associada à hipertensão, a qual foi evidenciada nos machos sob as mesmas condições. Assim o conjunto de alterações hemodinâmicas indica que as fêmeas sofreram um menor impacto do que camundongos machos nas alterações cardiovasculares estudadas. A expressão de NOS foi evidenciada na aorta das fêmeas LDLr-/- sob dieta comercial (CT), contudo ausente nas WT e, sob dieta hipercolesterolêmica (HC) a sua imunorreatividade foi menor que no animal controle porém expressiva e difusa , as expressões tanto no controle como no animal HC foram reduzidas pelo tratamento com a SNAC. Estas alterações indicaram a sua participação na disfunção endotelial presente neste modelo e o fato de que o efeito protetor promovido pela SNAC está associado às vias NO/NOS
Abstract: The incidence of risk of coronary artery disease (CAD) is greater in men than in woman during the reproducible years, and this gender difference diminishes after cessation of estrogen production after menopause (Kannel et al, 1976). Many studies have ben suggested also that this gender difference may be caused in part by proaterogenic actions of androgens. The aim this study was verify the role of the sexual dimorphism in LDLr-/- mice in the vasculoprotector effect treatment promoted by S-nitroso-N-acetilcisteína (SNAC) in the initial phase of atherogenesis valuation following:1- phenotypic expression of the hypertension; 2- lesion area development; 3- plasma lipid levels; 4- localization of NOS using immunohistochemistry; Male and female mice 3 months old were evaluated in experimental groups following: C57Bl/6 wild type (WT) chow diet; LDLr-/- control group (CT) chow diet; LDLr-/- hypercholesterolemic diet(HC); LDLr-/- hypercholesterolemic diet plus SNAC 0.51 µmol/Kg ip/daily (SNAC). After treatment for 2 weeks the female developed a 50% decrease lesion area in the proximal aortic as compared to males. This evidence indicated the protector role of the estrogen in female in the initial stage of atherosclerosis. The treatment with SNAC promoted a 50% reduction in installation of atherosclerosis in both sexes with no sexual dimorphism. In female the lesion area was not correlated with the average plasma cholesterol levels. Female mice LDLr-/- under a hypercholesterolemic diet showed an increase of 10% in blood pressure compared whith the background (WT). The treatment with SNAC prevented the hypertension induced by the hypercholesterolemic diet. Nevertheless male hypertension is associated with mice LDLr-/- and chow diet treatment does not prevent hypertension. These results showed that hypertension genesis is different in both sexes suggesting the participation of androgenic pathways. The males showed left ventricular hypertrophy and decreased heart rate associated with hypertension, but the female in the same conditions did not show. Thus is hemodynamic alteration set indicate that female have a less impact than male mice in the studied cardiovascular alterations. The expression of the three types of NOS was evident in aorta of the female LDLr-/- chow diet, although absent in WT. In female LDLr-/- hypercholesterolemic diet there was enhanced immunoreactivity. This overexpression was decreased by treatment with the SNAC. These alterations participated in endothelial dysfunction present in this model and the protector effect promoved by SNAC is associated with the NO/NOS pathways
Mestrado
Fisiologia
Mestre em Biologia Funcional e Molecular

Hipercolesterolemia familiar (HF) é uma doença autossômica dominante, caracterizada por elevados níveis plasmáticos da lipoproteína de baixa densidade (LDL), desenvolvimento de xantoma tendíneo e arco corneal, além do aumento do risco de doença coronariana e acidente vascular cerebral prematuros. Frequentemente subdiagnosticada, estima-se que apenas 10% dos 400.000 indivíduos com HF no Brasil têm conhecimento da própria doença; afetando, desta forma, a qualidade e a expetativa de vida dos pacientes. Mutações no gene do receptor da LDL (LDLR) são consideradas as alterações genéticas mais frequentes para o desenvolvimento da hipercolesterolemia familiar, pois comprometem a capacidade de remoção das partículas de LDL circulantes, promovendo seu aumento em níveis plasmáticos. Já foram descritas mais de 1600 mutações diferentes no gene LDLR associadas ao fenótipo da HF; entretanto, ainda é difícil determinar em muitas delas o efeito deletério na atividade do receptor. O objetivo desse estudo foi identificar e caracterizar funcionalmente mutações no gene LDLR não descritas na literatura para determinar sua patogenicidade na hipercolesterolemia familiar. Foi avaliada a atividade residual de LDLR através da captação de LDL marcado com fluoróforo lipofílico em cultura de linfócitos T dos pacientes portadores das mutações analisadas após estimulação dos linfócitos T por mitógenos específicos. As mutações Cys82Ser, Thr404Ser, Gly529Arg e His285Tyr foram consideradas patogênicas por acarretarem diminuição da atividade residual do receptor de LDL. As mutações Glu 602X e His388ProfsX53 confirmaram sua patogenicidade e podem ser considerados como controle positivo para futuros ensaios funcionais. Estudos que esclareçam os mecanismos moleculares da HF e da relação genótipo/fenótipo abrem perspectivas para o desenvolvimento de terapias mais específicas na redução dos níveis de colesterol e, consequentemente, da morbidade e mortalidade associadas às doenças cardiovasculares.
Familial hypercholesterolemia (FH) is an autosomal dominant disorder characterized by elevated plasma levels of low-density lipoprotein (LDL), and development of corneal arcus tendinous xanthoma, and increased risk of coronary heart disease and premature stroke. Often misdiagnosed, it is estimated that only 10% of the 400.000 patients with FH in Brazil has knowledge of the disease itself, affecting in this way the quality and life expectancy of patients. Mutations in the LDL receptor (LDLR) are considered the most frequent genetic alterations for the development of familial hypercholesterolemia because compromise the ability of removal of circulating LDL particles, promoting its increase in plasma levels. Have been described over 1600 different mutations in the LDLR gene associated with the phenotype of FH, however, it is still difficult to determine in many of the deleterious effects on receptor activity. The aim of this study was to identify mutations in the LDLR gene and functionally characterize mutations not described in the literature to determine its pathogenicity in familial hypercholesterolemia. The residual activity of LDLR was evaluated by raising LDL labeled with lipophilic fluorophore in cultured T lymphocytes of patients with the analyzed mutations after stimulation of T lymphocytes by specific mitogen. The substitution mutations Cys82Ser, Thr404Ser, Gly529Arg e His285Tyr were considered pathogenic because it causes decrease of the residual activity of the LDL receptor in T lymphocytes. The His388ProfsX53 and Glu602X mutations confirmed their pathogenicity and can be considered as positive control for future functional assays. Studies to clarify the molecular mechanisms of HF and genotype/ phenotype open perspectives for the development of more specific therapies for reducing cholesterol levels, and therefore the morbidity and mortality associated with cardiovascular diseases.

Leveraging miRNA-Seq data and the 1000 Genomes imputed genotypes, we identified rs174561-C as a strong miRQTL for circulating miRNA-1908-5p (P=4.8x10-31) which has an inverse relationship with circulating LDL-C, fasting glucose and A1c. Here I investigated the molecular mechanism(s) linking miR1908-5p to cholesterol metabolism. First, by overexpression experiments in HuH-7 cells demonstrate that the presence of the C allele, associated with lower LDL-C levels, significantly increases miR-1908-5p by 2.15-fold relative to the T allele. Further experiments revealed that 72-hour cholesterol depletion increases miR-1908-5p expression (2.11-fold) whereas cholesterol loading decreases miR-1908-5p expression (0.69-fold). Differential miR-1908-5p expression was then used to profile genes involved in lipoprotein signaling and cholesterol metabolism using a PCR array to identify LDLR as a gene of interest. Although total RNA and protein expression of LDLR was unchanged in response to differential miR-1908-5p expression, the ratio of the mature form to the cleaved form of LDLR decreased following miR-1908-5p inhibition (0.85-fold) and conversely, increased with mimic treatment (1.63-fold). Cleavage of the mature LDLR is known to reduce cell surface affinity for LDL. These findings uncover a potential mechanism linking miR-1908-5p to lower LDL-cholesterol levels through reduced LDLR cleavage.

Thesis (PhD) -- University of Stellenbosch, 2001.
ENGLISH ABSTRACT: The advent of the new millennium saw the complete sequencing of the entire human genome. Only approximately 30 000 genes, much less than was initially predicted, have been identified to be responsible for the genetic diversity in humans. This discovery has prompted a shift in the approach to disease research, since one gene can be involved in numerous diseases. This phenomenon seems to be especially true for the low-density lipoprotein receptor (LDLR) gene. Various substances beside sterols can induce transcription of the LDLR gene. Non-communicable diseases (e.g. hypertension) are common in the developing world and contribute significantly to mortality rates. The fmding that a promoter variant (-175 g~t) in the LDLR gene is associated with elevated diastolic blood pressure may explain the phenomenon of high LDL-cholesterollevels in hypertensive individuals. Studies have demonstrated that the lowering of cholesterol, especially LDL-cholesterol, can reduce the incidence of hypertension. The -175 g~t variant is located in a newly described cis-acting regulatory element which contains a putative binding site for Yin Yang (YY)-l and also demonstrates great homology to the cAMP response element (CRE) which bind the Ca2+- dependent transcription factor, CRE binding protein (CREB). The fact that Ca2+ can induce transcription of the LDLR gene may, at least in part, explain the association between the - 175g~t variant and elevated diastolic blood pressure. Cholesterol is important for various processes, such as apoptosis, maintenance of cellular membranes and immune function. The -59 c-ot mutation in repeat 2 of the LDLR gene abolishes binding of the sterol regulatory element binding protein(SREBP) to the SRE-l site. SREBP is proteolytically activated during apoptosis by two caspases (CPP32 and Mch3) to induce cholesterol levels. Our results imply that the -59C/T mutation, in repeat 2 of the LDLR gene promoter, may inhibit apoptosis under normal immunological conditions. Atherosclerosis can be considered an immunological disease, since various humoral and cellular immune processes can be detected throughout the course of the disease. The fmding that certain lipoproteins can protect against infection by binding and lysing of pathogens, or competing with pathogens for cellular receptors, prompted the investigation into the potential role of variation in the LDLR gene promoter in immune function. A significant difference in allelic distribution was detected between asymptomatic HIY -infected subjects and fast progressors for the -124 c-ot variant (P=O.006), shown to increase (~160%) transcriptional activity of the LDLR gene. Of relevance to this particular study is the fact that human herpesvirus (HHV) 6 can transactivate CD4 promoters through a partial CRE site. It has been shown that the CREB and YYl can regulate viral and cellular promoters, and these transcription factors can potentially bind to the LDLR promoter at the FP2 site. The mutation enrichment in the LDLR gene promoter seen in the South African Black and Coloured population groups can possibly provide insight into the pathogenesis of various diseases. This could also potentially, provide novel targets for treatment, since manipulation of cholesterol levels may affect the pathogenesis of various diseases.
AFRIKAANSE OPSOMMING: Die volledige DNA volgorde bepaling van die mensgenoom is voltooi vroeg in die nuwe millennium. Slegs ongeveer 30 000 gene is geidentifiseer, heelwat minder as wat in die verlede voorspel is, wat verantwoordelik is vir die genetiese diversiteit in die mens. Hierdie ontdekking het gelei tot 'n verandering in die benadering van navorsing ten opsigte van siektes, aangesien een geen 'n rol by verskeie siektes kan speel. Hierdie gewaarwording blyk veral waar te wees vir die lae digtheids lipoproteien reseptor (LDLR) geen. Verskeie stimuli, buiten sterole, kan transkripie van die LDLR geen inisieer. Verskeie siektes soos hipertensie is algemeen in die ontwikkelende wereld, en dra by tot die hoe mortaliteit syfers. Die bevinding dat 'n promoter variant in die LDLR geen (-175g-H) geassosieer is met verhoogde diastoliese bloeddruk, kan moontlik verhoogde lipiedvlakke in hipertensiewe individue verklaar. Studies het aangetoon dat die verlaging van cholesterol, veral LDL-cholesterol, die voorkorns van hipertensie kan verlaag. Die -175 g~t variant is gelee in 'n cis-regulerende element wat na bewering 'n bindingsetel vir die Yin Yang (YY)-l transkripsie faktor bevat asook sterk homologie met die cAMP respons element (CRE) toon, wat bind aan die Ca2 +_ afhanklike transkripie faktor, CRE bindings proteiene (CREB). Die feit dat Ca2+ transkripsie van die LDLR geen kan inisieer, kan dalk tot 'n mate, 'n verklaring bied vir die assosiasie tussen die -175 (g~t) variant en verhoogde diastoliese bloeddruk. Cholesterol is noodsaaklik vir verskeie prosesse soos apoptose, die instandhouding van selmembrane sowel as immuun funksies. Die -59 c-ot mutasie in die sterol regulerende element 1 (SRE-l) van die LDLR geen vernietig binding van die sterol regulerende element bindingsprotei'en (SREBP) aan SRE-l. SREBP word proteolities geaktiveer tydens apoptose deur twee kaspases (CPP32 en Mch3) om cholesterolvlakke te induseer. Ons resultate impliseer dat die -59C/T mutasie, in herhaling-2 van die LDLR-geen promoter, apoptose kan inhibeer onder normale immunologiese toestande. Aterosklerose kan beskou word as 'n immunologiese siekte, aangesien verskeie humorale en sellulere immuun prosesse deur die verloop van die siekte waargeneem kan word. Die feit dat Iipoproteiene beskermend kan wees teen infeksies, deur binding en lisering van virusse of kompeteer met patogene vir sellulere reseptore, het aanleiding gegee tot 'n ondersoek na die potensiele rol van variasies in die promoter area van die LDLR geen in immuun funksie. Betekenisvolle verskille in alleel verspreiding vir die -124c~t variant (P=0.006) is waargeneem tussen asimptomatiese MIV -geinfekteerde pasiente en individue met vinnige siekte progressie. In vitro studies het voorheen getoon dat die -124c~t 'n verhoging in LDLR geen transkripsie (160%) tot gevolg het. Dit is noemenswaardig dat 'n vroee studie getoon het dat die mens like herpesvirus-6 (MHV6) transaktivering van die CD4 promoters deur 'n gedeeltelike CRE bindingsetel kan bewerkstellig. Beide CREB en YYl kan virus en sellulere promotors reguleer, en hierdie transkripsie faktore toon bindingshomologie met die FP2 element van die LDLR promotor Die mutasie verryking van die LDLR geen promoter soos waargeneem in Suid Afrikaanse Swart en Kleurling populasies, kan moontlik lig werp op die patogenese van verskeie siektetoestande. Hierdie bevindinge kan potensieel nuwe teikens vir behandeling identifiseer, aangesien manipulasie van cholesterolvlakke 'n effek mag he op die patogenese van verskeie siektes.

Cholesterol is an essential component of the plasma membrane however if present in excess, free cholesterol is toxic to cells and can lead to complications such as atherosclerosis, and ultimately cardiovascular disease. The low density lipoprotein receptor binds and internalises circulating plasma cholesterol, present in low density lipoprotein molecules. The low density lipoprotein receptor has two main transcriptional regulators: liver X receptors and sterol regulatory element binding proteins and post-transcriptional regulators, namely the E3-ubiquitin ligase IDOL, which binds and ubiquitinates the low density lipoprotein receptor intracellular tail, targeting it for lysosomal degradation. Several protein-protein interactions are required for the ubiquitination activity of IDOL, serving as potential therapeutic modulation sites for the treatment of hypercholesterolemia via an upregulation of low density lipoprotein receptor protein levels. Bacterial reverse-two hybrid systems were designed for the IDOL-LDLR heterodimerisation and the IDOL homodimerisation interactions. The latter system was used to screen a library of 3.2 million cyclic peptides, identifying a series of peptides capable of inhibiting the IDOL homodimerisation event. These peptides were synthesised and their activity assessed using a selection of in vitro assays, providing a lead candidate. The efficacy of the lead candidate peptide was improved through the development of a small library of non-natural derivatives, improving binding activity by 7-fold. The activity of the new generation peptide was assessed both in vitro for ability to inhibit autoubiquitination and in hepatic cells, elucidating biological implications of the inhibition of IDOL mediated LDLR degradation.

A hipercolesterolemia familiar (HF) é uma doença autossômica dominante causada por mutações no gene do receptor de LDL (LDLR) (cromossomo 19p13.1 - p13.3), que alteram parcialmente ou totalmente a função do LDLR. A HF é também uma das doenças genéticas mais comuns com freqüências estimadas de heterozigotos e homozigotos de 1/500 e 1/1.000.000, respectivamente. Manifesta-se com altos níveis de LDL colesterol, arco corneal, xantomas tendíneos e sintomas prematuros de doença coronariana.. A grande heterogeneidade observada na manifestação clínica desta doença pode ser explicada, ao menos parcialmente, pelo amplo espectro de mutações no gene do LDLR. O presente estudo teve por objetivo a caracterização molecular do gene LDLR em pacientes com HF do Rio Grande do Sul (RS), Brasil. Para isso, foram obtidas amostras de DNA de 40 indivíduos provenientes de cinco macrorregiões do Estado, representando seis diferentes populações de ascendência européia, para a realização do seqüenciamento direto do gene do LDLR, com posterior análise por meio das ferramentas de bioinformática. Quinze mutações pontuais foram identificadas no gene do LDLR, a saber: c.408C>T (D115D), c.1616C>T (P518L), c.1773C>T (N570N) e c.2243A>G (D727G) na região codificadora, IVS6+36G>A, IVS6+171G>A, IVS11+56C>T, IVS11- 69G>T, IVS11-55A>C, IVS15-136A>G, IVS16+46C>T e IVS17-42A>G na região intrônica, e *52G>A, *105T>G e *141G>A na região 3\'-UTR. Destas, oito ainda não foram descritas na literatura (três situadas nos exons, quatro nos introns e uma na região 3\'-UTR). A mutação*52G>A foi previamente identificada em pacientes com HF da região Sudeste do Brasil, sugerindo que possa exercer um importante efeito na patogênese da HF em pacientes brasileiros. Em relação às macrorregiões do RS, os portugueses, italianos e espanhóis apresentaram o maior número de mutações dentre os grupos étnicos analisados. Assim, os resultados obtidos confirmam que existe um amplo de espectro de mutações no gene do LDLR. As mutações nas regiões intrônicas precisam ser investigadas sobre seu efeito potencial no desenvolvimento de HF. Considerando que este é o primeiro estudo que teve por objetivo a caracterização molecular de pacientes com HF no RS, novos estudos que visem a elucidação das bases moleculares da HF devem ser realizados, a fim de obter uma melhor caracterização genética desta doença no Brasil.
Familial hypercholesterolemia (FH) is an autosomal dominant disorder caused by mutations in the low-density lipoprotein receptor (LDLR) gene (chromosome 19p13.1 - p13.3), which alter partially or totally the LDLR function. FH is also one of the most common inherited disorders with frequencies of heterozygotes and homozygotes estimated to be 1/500 and 1/1.000.000, respectively. Affected individuals display high levels of LDL cholesterol, arcus corneae, tendon xanthomas and premature symptomatic coronary heart disease. The extensive heterogeneity observed in the clinical manifestation of this disorder may be explained, at least partially, by the broad spectrum of mutations identified in the LDLR gene. The present study had as the main goal the molecular characterization of the LDLR gene in patients with FH from Rio Grande do Sul (RS) State, Brazil. For this, DNA samples were obtained from 40 individuals living in five macroregions of RS, representing six different isolated populations of European ascendancy. The LDLR gene was subjected to the direct sequencing with further analysis through bioinformatics tools. Fifteen punctual mutations were identified in the LDLR gene, namely: c.408C>T (D115D), c.1616C>T (P518L), c.1773C>T (N570N) and c.2243A>G (D727G) in the coding region, IVS6+36G>A, IVS6+171G>A, IVS11+56C>T, IVS11-69G>T, IVS11-55A>C, IVS15-136A>G, IVS16+46C>T and IVS17-42A>G in the intronic region, and *52G>A, *105T>G and *141G>A in the 3\'-UTR region. Of these, eight were not yet described in the literature (three situated in exons, four in introns and one in 3\'- UTR region). The *52G>A mutation was previously identified in FH patients from Southeast Brazil, suggesting that it can exert an important effect in the pathogenesis of FH in Brazilian patients. In relation to the macroregions of Rio Grande do Sul, Portuguese, Italian and Spanish subjects carried the highest number of mutations among the ethnic groups analyzed. Thus, the results obtained confirm the existence of a broad spectrum of mutations in the LDLR gene. The mutations in intronic regions need to be investigated in relation to its potential effect in the development of FH. Taking into account that this is the first study that had as the goal the molecular characterization of FH patients in RS, further studies aimed at elucidating the molecular bases of FH should be performed, in order to obtain the better characterization of this disease in Brazil.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.
Includes bibliographical references (p. 87-90).
The study of correlations between residues in distal regions of a protein structure may provide insights into the mechanism of protein folding. Such long-range correlations may exist between distant residues that are conserved by evolution or physically related by motion. Two computational approaches, one involving hidden Markov models (HMMs) and the other applying molecular dynamics (MD), were implemented to identify a comprehensive set of residue couplings, as well as provide possible explanations for the correlations. HMMs were employed to model the secondary structural elements of proteins in order to discover residues correlated by coevolution. MD simulations and cross-correlation analyses were performed to determine residues coupled by motion. The protein system that was chosen for the study of long-range correlated residues was the fifth binding module (LR5) of the low-density lipoprotein receptor (LDLR) which regulates the cholesterol level in the bloodstream.
(cont.) The LR5 repeat is crucial to the binding of LDLR to lipoprotein particles that carry cholesterol. The HMM and MD approach identified correlations between residues that have been postulated to bind to a particular type of lipoprotein and residues involved in calcium ion coordination which maintains the folding of the LDLR structure. Energetic pathways of the LR5 module were constructed to provide insights into structural stability and functional importance of the residue couplings.
by Jennifer W. Lin.
M.Eng.

Orientadora: Angelina Zanasco
Coorientadora: Camila de Moraes
Banca: Maria Andréia Delbin
Banca: Alexandre Gabarra de Oliveira
Resumo: A inatividade física e as dislipidemias são considerados fatores de risco para a gênese das doenças cardiovasculares. Estudos em animais mostram que o consumo de dieta contendo alto teor de lipídios leva à diminuição da resposta relaxante dependente do endotélio, o que pode ser prevenido pela realização de exercício físico. Entretanto, a maioria dos estudos investigou os efeitos do exercício físico em artérias de maior calibre e em modelos de dislipidemia induzida por dieta. Há escassez de estudos que avaliam os efeitos do exercício físico em artéria de menor calibre e, principalmente, em modelo que mimetiza a hipercolesterolemia familiar (HF). Portanto, o objetivo do presente estudo foi avaliar o efeito do treinamento físico aeróbio de moderada intensidade na reatividade vascular da artéria ilíaca em camundongos knockout para o receptor de LDL alimentados com dieta hiperlipídica. Foram utilizados camundongos wild type e knockout para o receptor de LDL (LDLR-/-) divididos em quatro grupos experimentais: wild type sedentário (WT), wild type treinado (WT/Ex), knockout sedentário (KO) e knockout treinado (KO/Ex). Os grupos WT foram alimentados com ração balanceada e os grupos KO com dieta hiperlipídica (38% lipídios). Os grupos WT/Ex e KO/Ex realizaram corrida em esteira (60-70%Vmax, 5 dias/semana, 60 min) durante oito semanas. A reatividade vascular em artéria ilíaca foi verificada através de curvas concentração-resposta a acetilcolina (ACh), nitroprussiato de sódio (SNP), fenilefrina (PHE) e ao análogo do tromboxano A2 (U46619). A determinação da produção de óxido nítrico (NO) foi realizada pela análise de fluorescência ao 4,5-diaminofluoresceína (DAF-2) e a produção de ânion superóxido pela análise da fluorescência derivada da oxidação da dihidroetidina (DHE). Foi quantificada ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Physical inactivity and dyslipidemia are considered risk factors for cardiovascular disease. A decrease in endothelium-dependent relaxation response, which can be prevented by physical exercise, had been showing in animals fed with high fat diet. However, most studies investigated the effects of physical exercise on large-caliber arteries using models of diet induced dyslipidemia. There are few studies that evaluate the effects of physical exercise in small-caliber artery and, mainly, in a model that mimics familial hypercholesterolemia (FH). Therefore, the aim of this study was to evaluate the effect of moderate intensity exercise training on vascular reactivity of iliac artery in FH model using mice lacking LDL receptor. Wild type and knockout mice (LDLR-/-) were divided into four groups: sedentary control (WT), trained control (WT/Ex), sedentary knockout (KO) and trained knockout (KO/Ex). Control groups were fed with standard chow and knockout groups with high fat diet. Trained groups ran on a treadmill (60-70% Vmax, 60 min, 5 days/week for 8 weeks). Concentration-response curves to acetylcholine (ACh), sodium nitroprusside (SNP), phenylephrine (PHE) and thromboxane A2 analogue (U46619) were done in iliac artery rings. Arterial production of nitric oxide and oxygen reactive species formation were assessed using fluorescence analysis (DAF-2 and DHE). Serum concentration of glucose, total cholesterol and triglyceride were determined using commercial kits. After eight weeks, the KO group had higher body weight gain (around 640%), epididymal fat (510%), glucose (35%), total cholesterol (180%) and triglycerides (99%) compared with WT group. Exercise training was effective to prevent body weight and epididymal fat gain in KO/Ex group (less 167% and 121%, respectively). No changes were observed in glucose, total cholesterol and triglycerides ... (Complete abstract click electronic access below)
Mestre

LDLR-W66G est une mutation « faux sens » dans le gène du récepteur des lipoprotéines LDL (LDLR), associée à l'expression deThypercholestérolérnïe familiale (HF) dont la prévalence dans la région du Saguenay-Lac-Saint-Jean (SLSJ) est particulièrement élevée (environ une personne sur 80). L'objectif de cette étude est de mesurer les déterminants démogénétiques qui expliquent la fréquence et la distribution de cette mutation dans la population saguenayenne. Les résultats des analyses démogénétiques effectuées sur les généalogies des 64 sujets affectés, recrutés au SLSJ, et des témoins montrent une concentration des ancêtres et un apparentement significativement plus élevés parmi les sujets, Cependant, les résultats concernant les ancêtres immigrants ne permettent pas d'identifier de façon claire le ou les individus susceptibles d'avoir introduit la mutation W66G dans la population québécoise.

Low density lipoprotein receptor (LDLR) is an apolipoprotein E (apoE) receptor and may play a role in Alzheimer’s disease (AD) development. A single nucleotide polymorphism (SNP), rs688, that has been identified to modulate the splicing efficiency of LDLR exon 12 and is associated with higher cholesterol and AD in some case-control populations. The exon 12 deleted mRNA is predicted to produce a soluble form of LDLR that fails to mediate apoE uptake. To gain additional insights, in this study, I seek to understand the regulation of LDLR splicing efficiency. To identify functional cis-elements within LDLR exon 12, I mutated several conserved putative exonic splicing enhancers (ESEs) to neutralize their affinity to serine/arginine-rich (SR) proteins. Transfection of wild type (WT) or mutant LDLR minigenes in HepG2 cells was performed, and splicing efficiency evaluated by quantitative RT-PCR. The results showed that two functional ESEs within exon 12, near rs688, are critical to LDLR splicing. To identify splicing factors that modulate exon 12 splicing, I co-transfected an LDLR minigene and vectors encoding different SR proteins and heterogeneous nuclear ribonucleoproteins (hnRNPs). After quantifying the splicing efficiency, I found that SRp20 and SRp38 increased exon 11- skipping. Moreover, ectopic expression of SRp38-2 and hnRNP G increased exon 11&12-skipping. Interestingly, the actions of hnRNP G did not require its RNA recognition motif (RRM). To further investigate the role of theses splicing factors on LDLR splicing, I quantified the expression level of these splicing factors as well as LDLR splicing efficiency in human brain and liver. I found that SRp38 mRNA expression is associated with LDLR splicing efficiency. In conclusion, this study discovered that rs688 is located close to the two functional ESEs within LDLR exon 12, and revealed a role of SRp38 in LDLR splicing efficiency.

Orientadores: Marta Helena Krieger, Regina Celia Spadari-Bratfisch
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-08T07:50:11Z (GMT). No. of bitstreams: 1 Garcia_JoseAntonioDias_D.pdf: 1987747 bytes, checksum: 1ec8d731703522ccf42a42dafd7b13a7 (MD5) Previous issue date: 2006
Resumo: Recentemente demonstrou-se que S-nitroso-N-acetilcisteína (SNAC) atenua o desenvolvimento da placa de aterosclerose na aorta em cerca de 55% de camundongos deficientes do receptor de lipoproteína de baixa densidade (LDLr-/-). O presente estudo teve como objetivo: i) verificar se a deleção do gene do receptor de LDL pode alterar o perfil hemodinâmico e a resposta inotrópica do coração a agentes adrenérgicos; ii) determinar a capacidade do SNAC na prevenção das alterações estruturais e funcionais do miocárdio e; iii) verificar o efeito do SNAC na pressão arterial de camundongos hipercolesterolêmicos. Camundongos machos C57BL6 (Wild Type = WT) e camundongos LDLr-/- (S) foram alimentados com dieta comercial por 15 dias. Em relação aos camundongos WT, os camundongos S apresentaram aumento de 11% na pressão arterial, diminuição de 62% na contratilidade do átrio esquerdo, e aumento na expressão do CD40L e redução na expressão de NOSe no tecido ventricular esquerdo. Camundongos LDLr-/- alimentados com dieta enriquecida em 1,25% de colesterol, 20% de gordura e 0,5% de ácido cólico por 15dias (Chol) apresentaram hipertrofia ventricular esquerda (HVE) comparados aos camundongos S, a qual foi caracterizada por: a) aumento de 1,25 vezes na razão entre o peso ventricular esquerdo (mg) e o peso corporal (g) (4,17±0,09 vs 3,34±0,07 mg/g, respectivamente; p< 0,05); b) aumento do diâmetro dos cardiomiócitos (25±0,6 vs 19±0,7 µm, p<0.05); c) aumento na expressão das isoformas das NOS (óxido nítrico sintases) e hiperexpressão do CD40L; d) aumento do depósito de colágeno; e) sem alterações na performance contrátil do átrio esquerdo e na responsividade à noradrenalina. A administração do SNAC aos camundongos Chol (chol+SNAC) (0,51 µmol/kg/dia, i.p.), preveniu o aumento na razão do peso ventricular esquerdo (mg) e o peso corporal (g) (3.38±0.23 mg/g), no diâmetro dos cardiomiócitos (20±0.7 µm), no deposito de colágeno, na expressão das isoformas da NOS e a hiperexpressão do CD40L. O SNAC não apresentou efeito no aumento da pressão arterial e nem sobre a hipocontratilidade, mas recuperou a responsividade para noradrenalina. Em conclusão, o presente estudo demonstrou que camundongos com deleção do gene do receptor LDL apresentaram hipertensão e marcada redução contrátil. Essas características podem estar relacionados com o estresse oxidativo resultante do processo inflamatório e da hipoexpressão da NOSe. A dieta hiperlipídica promoveu hipertrofia ventricular esquerda (HVE), devida ao aumento nos processos inflamatório e oxidativo. O SNAC impediu o desenvolvimento da HVE por mecanismos que envolveram efeito antiinflamatório (detectado pela diminuição na expressão do CD40L), a hiperexpressão das NOS, a redução das alterações estruturais ventriculares induzidas pela hipercolesterolemia de maneira independente da hipertensão. No presente estudo, a necessidade de quantificar as análises histológicas exigiu a validação de um software interativo para analisar imagens de amostras teciduais. O software foi projetado para permitir que o usuário altere os tipos de coloração vermelha, verde e azul (RGB) para uma cor padrão que possa ser usada para segmentar a imagem e calcular a fração da área de interesse. Os resultados obtidos com a contagem manual e com a contagem feita com o uso do software foram similares, indicando que são métodos alternativos confiáveis para análises quantitativas de cortes histológicos. Entretanto, o software permite processar as imagens de maneira eficiente e confiável, além de reproduzir o corte tecidual em um menor tempo, e pode ser executado com o microscópio e o computador padrão
Abstract: Recently, it has been that S-nitroso-N-acetylcysteine (SNAC) attenuate in 55% the plaque development in low-density lipoprotein-receptor-deficient (LDLr-/-) mice fed a hypercholesterolemic diet for 15 days. The present study was designed to verify whether deletion of the low-density lipoprotein (LDL) receptor gene may affect the hemodynamic profile and adrenergic inotropic cardiac responses and, particularly, to identify the ability of SNAC to prevent the myocardial alterations and hypertension in hypercholesterolemic mice. C57BL6 wild-type (WT) and LDLr-/- male mice (S) were fed a commercial diet for 15 days. Control mice (S) showed 11 % blood pressure increase, 62% left atrial contractility decrease, CD40L overexpression and eNOS underexpression in comparison to WT. LDLr-/- mice which were fed for 15 days with 1,25% cholesterol, 20% of fat and 0.5% of colic acid enriched diet (Chol), showed significant left ventricular hypertrophy (LVH) versus S, which was characterized by: a) 1.25-fold increase in the LV weight (mg)/body weight (g) ratio (4.17±0.09 vs. 3.34±0.07 mg/g, respectively; p<0.05); b) increased cardiomyocyte diameter (25±0.6 vs. 19±0.7 µm, p<0.05); c) enhanced expression of the constitutive and inducible NOS isoforms and CD40L;d) increased collagen deposit; e) no alteration in the atrial contractile performance or responsiveness to norepinephrine. Administration of SNAC to Chol mice ( Chol +SNAC) (0.51 µmol/kg/day, for 15day, i.p.) prevented increases in the left ventricular weight/body weight ratio (3.38±0.23 mg/g), cardiomyocyte diameter (20±0.7 µm), collagen deposit, NOS isoforms and CD40L overexpression, but had no effect on increased blood pressure or atrial basal hypocontractility, although it recovered responsiveness to norepinephrine. In conclusion, the present study demonstrated that the deletion of the LDL receptor gene in mice determined hypertension and a marked left atrial contractile deficit. These findings may be related to oxidative stress, resulting from inflammation and eNOS underexpression. High-cholesterol diet promoted LVH in LDLr-/- mice associated with enhanced inflammatory and oxidant processes. SNAC prevented LVH by processes that involved decreased CD40L expression and NOS overexpression effects attenuating the ventricular structural alterations induced by hypercholesterolemia independent of hypertension. Histological quantization demanded the development of interactive software for image analysis of tissue samples. The software was designed to allow a user-oriented change of a chosen red, green and blue (RGB) staining in a standardized color that can be used to segment the image and calculate the fractional area of interest. Thus the method allows efficient, reliable and reproducible processing of tissue sections that is less time-consuming than conventional methods and can be performed with standard microscope and computer
Doutorado
Fisiologia
Doutor em Biologia Funcional e Molecular

La distribution de principes actifs dans le système nerveux central (SNC) est entravée par la présence d'une barrière physiologique, la barrière hémato-encéphalique (BHE). L'endothélium cérébral est pourvu d'un large éventail de systèmes de transport, parmi lesquels la trancytose récepteur-dépendante, qui peut être mise à profit pour vectoriser toute une gamme d'agents thérapeutiques vers le SNC de manière non invasive. Dans le cadre de cette approche, le LDLR (Low Density Lipoprotein Receptor), exprimé à la surface de la BHE, est une cible particulièrement intéressante. L'objectif de ce travail est le développement de nouveaux ligands du LDLR en tant que vecteurs potentiels de la BHE. Le criblage d'une librairie de peptides aléatoires dirigée contre le LDLR a permis l'identification d'un peptide 15-mer cyclique ayant une haute affinité in vitro. Une étude des relations structure/activité a ensuite été menée afin d'améliorer l'affinité pour le LDLR et d'augmenter la stabilité plasmatique de ce peptide. Cette étude a abouti à l'identification d'un nouveau peptide « lead » qui a été conjugué à des molécules actives afin d'évaluer la capacité du peptide à vectoriser un principe actif à travers la BHE après administration in vivo chez la souris
Drug delivery to the central nervous system (CNS) is hindered by the presence of a physiological barrier, the blood-brain barrier (BBB). The brain endothelium is endowed with a series of transport systems, including receptor-mediated transcytosis. This system can also be used to transport therapeutics into the brain as a non-invasive manner. Among receptors expressed on the BBB, the low density lipoprotein receptor (LDLR) is relevant as a drug delivery system. This project is dedicated to the development of new peptide-based ligands of LDLR as potential BBB-vectors. The screening of a random peptide library directed to the LDLR led to the identification of hits such as a cyclic 15-mer peptide with high in vitro affinity. A structure/activity relationship study was then carried out in order to improve its affinity towards the LDLR and to increase its plasmatic stability. This study led to the identification of a new lead peptide which was conjugated to bioactive compounds in order to assess the ability of our peptide to shuttle a drug across the BBB following in vivo administration in mice

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Inflammatory process, endothelial dysfunction and oxidative stress in cardiovascular environment resulting from dyslipidemia are the conditions that promote and sustain atherosclerosis and cardiac hypertrophy. The present study verified the effect of propolis alone and its association with swimming in dyslipidemia, left ventricular hypertrophy and atherogenesis of hypercholesterolemic mice that were receiving a high-fat diet. 40 LDLr-/- mice, fed with high fat diet (20% total fat, 1.25% cholesterol and 0.5% cholic acid) ad libitum for 75 days, were used in the study. The animals were divided into 4 groups (n=10): hyperlipidic group (HL), sedentary, subjected to aquatic stress; hyperlipidic + swimming group (HL+NAT), submitted to a swimming protocol (1 hour per day, 5 times per week) from the 16th day of the experiment; hyperlipidic + propolis group (HL+PRO), sedentary, submitted to aquatic stress and which received oral propolis (70 µL of the propolis alcoholic extract of 85,71% every weekday) from the 16th day of the experiment; HL+NAT+PRO group, submitted to swimming protocol (1 hour per day, 5 times per week) from the 16th day of the experiment and which received oral propolis (70 µL of the propolis alcoholic extract of 85,71% every weekday) from the 16th day of the experiment. After 75 days of the experiment, the animals were weighed and anesthetized. Blood was collected and laboratory analyzes were performed for total cholesterol and fractions, and triglycerides. After thoracotomy, heart and aorta were removed. The heart was weighed and dissected, the left ventricle isolated, the ratio between the ventricular weight (mg) and the animal weight (g), was calculated and after, it was histologically processed. Ventricle and aorta slides were stained with hematoxina and eosin (HE) and picrosirius red for histological and histochemical analyzes; other slides were treated immunohistochemically with anti-protein proinflammatory CD40L antibodies to evaluate the inflammatory process. The HL animals showed severe dyslipidemia, atherogenesis and left ventricular hypertrophy, associated with a decrease in serum high density lipoprotein (HDL) levels and subsequent development of cardiovascular anti-inflammatory process, characterized by increased expression of CD40L in the left ventricle and aorta. Swimming and propolis separated and / or associated prevented left ventricular hypertrophy (HVE), atherogenesis, ventricular and arterial inflammation, decreasing the expression of CD40L and increased plasma levels of HDL-C. A propolis alone or associated with regular physical activity is beneficial in cardiovascular protection by anti-inflammatory action.
O processo inflamatório, a disfunção do endotélio e o estresse oxidativo no ambiente cardiovascular decorrente das dislipidemias são as condições que promovem e sustentam a aterosclerose e a hipertrofia cardíaca. O presente estudo verificou o efeito da própolis isolada e da sua associação com a natação na dislipidemia, na hipertrofia ventricular esquerda e na aterogênese de camundongos hipercolesterolêmicos que já recebiam dieta hiperlipídica. Foram utilizados 40 camundongos LDLr-/- alimentados com dieta hiperlipídica (20% de gordura total, 1,25% de colesterol e 0,5% de ácido cólico) ad libitum por 75 dias. Os animais foram divididos em 4 grupos (n=10): grupo hiperlipídico (HL), sedentário, submetido ao estresse aquático; grupo hiperlipídico + natação (HL NAT), submetido a um protocolo de natação (1 hora por dia, 5 vezes por semana) a partir do 16º dia do experimento; grupo hiperlipidico/própolis (HL PRO), sedentário, submetido ao estresse aquático e que recebeu própolis via oral (70 µL do extrato alcoólico de própolis a 85,71% todos os dias da semana) a partir do 16º dia do experimento; grupo HL NAT PRO, submetido a um protocolo de natação (1 hora por dia, 5 vezes por semana) a partir do 16º dia do experimento e que recebeu própolis via oral (70 µL do extrato alcoólico de própolis a 85,71% todos os dias da semana) a partir do 16º dia do experimento. Após os 75 dias de experimento, os animais foram pesados e anestesiados. O sangue foi coletado e foram realizadas as análises laboratoriais de colesterol total e frações, e triglicerídeos. Após a toracotomia, o coração e a artéria aorta foram removidos. O coração foi pesado e dissecado, o ventrículo esquerdo isolado, calculou-se a razão entre peso ventricular (mg) e peso animal (g), e, em seguida, foi processado histologicamente. Lâminas do ventrículo e aorta foram coradas com hematoxina e eosina (HE) e picrosírius red para análise histológica e histoquímica; outras lâminas foram tratadas imunohistoquimicamente com anticorpos antiproteína pró-inflamatória (CD40L) para avaliar o processo inflamatório. Os animais HL apresentaram dislipidemia severa, aterogênese e hipertrofia ventricular esquerda associada a uma diminuição dos níveis séricos da lipoproteína de alta densidade (HDL) e consequente desenvolvimento de processo anti-inflamatório cardiovascular caracterizado pelo aumento da expressão CD40L no ventrículo esquerdo e na aorta. A natação e a própolis separadas e/ou associadas preveniu a hipertrofia ventricular esquerda (HVE), a aterogênese, a inflamação ventricular e arterial, diminuindo a expressão de CD40L e aumentando os níveis plasmáticos da HDLc. A própolis isolada ou associada com uma atividade física regular é benéfica na proteção cardiovascular por ação anti-inflamatória.

Since apoE allele status is the predominant Alzheimers disease (AD) genetic risk factor, functional single nucleotide polymorphisms (SNPs) in brain apoE receptors represent excellent candidates for association with AD. Therefore, three low density lipoprotein receptor (LDLR) SNPs were evaluated by TaqMan allelic discrimination assays for association with AD and I found that certain haplotypes alter the odds of AD. A SNP within LDLR exon 12, rs688, was identified in silico as neutralizing a putative exon splicing enhancer (ESE). Since LDLR is a major apoE receptor in the brain, I hypothesized that rs688 modulates LDLR splicing in neural tissues and associates with AD. To evaluate this hypothesis, I analyzed splicing patterns in human hippocampus samples and established that this SNP was associated with significantly decreased LDLR exon 12 splicing efficiency when the minor allele T is present in vivo. Lastly, I evaluated whether rs688 associates with AD by genotyping DNA from the Religious Orders Study (ROS) series. The rs688T/T genotype was associated with increased AD odds in males, but not in females, in a dataset consisting of 1,457 men and 2,055 women drawn from three case-control series. The rs688T/T genotype was associated with increased AD odds in males (recessive model, odds ratio (OR) of 1.49, 95% confidence interval (CI) of 1.13- 1.97, uncorrected p=0.005), but not in females. In summary, these studies identify a functional apoE receptor SNP that is associated with AD in a sex-dependent fashion.

Résumé : Les maladies cardiovasculaires représentent la principale cause de mortalité mondiale, soit le tiers des décès annuels selon l’Organisation mondiale de la Santé. L’hypercholestérolémie, caractérisée par une élévation des niveaux plasmatiques de lipoprotéines de faible densité (LDL), est l’un des facteurs de risque majeur pour les maladies cardiovasculaires. La proprotéine convertase subtilisine/kexine type 9 (PCSK9) joue un rôle essentiel dans l’homéostasie du cholestérol sanguin par la régulation des niveaux protéiques du récepteur LDL (LDLR). PCSK9 est capable de se lier au LDLR et favorise l’internalisation et la dégradation du récepteur dans les lysosomes. L’inhibition de PCSK9 s’avère une cible thérapeutique validée pour le traitement de l’hypercholestérolémie et la prévention des maladies cardiovasculaires. Par contre, plusieurs mécanismes responsables de la régulation et la dégradation du complexe PCSK9-LDLR n’ont pas encore été complètement caractérisés comme la régulation par la protéine annexin A2 (AnxA2), un inhibiteur endogène de PCSK9. De plus, plusieurs évidences suggèrent la présence d’une ou plusieurs protéines, encore inconnues, impliquées dans le mécanisme d’action de PCSK9. Celles-ci pourraient réguler l’internalisation et le transport du complexe PCSK9-LDLR vers les lysosomes. Les objectifs de cette thèse sont de mieux définir le rôle et l’impact de l’AnxA2 sur la protéine PCSK9 en plus d’identifier de nouveaux partenaires d’interactions de PCSK9 pour mieux caractériser son mécanisme d’action sur la régulation des niveaux de LDLR. Nous avons démontré que l’inhibition de PCSK9 par l’AnxA2 extracellulaire s’effectue via sa liaison aux domaines M1+M2 de la région C-terminale de PCSK9 et nous avons mis en évidence les premières preuves d’un contrôle intracellulaire de l’AnxA2 sur la traduction de l’ARNm de PCSK9. Nos résultats révèlent une liaison de l’AnxA2 à l’ARN messager de PCSK9 qui cause une répression traductionnelle. Nous avons également identifié la protéine glypican-3 (GPC3) comme un nouveau partenaire d’interaction extracellulaire avec le PCSK9 et intracellulaire avec le complexe PCSK9-LDLR dans le réticulum endoplasmique des cellules HepG2 et Huh7. Nos études démontrent que GPC3 réduit l’activité extracellulaire de PCSK9 en agissant comme un compétiteur du LDLR pour la liaison avec PCSK9. Une meilleure compréhension des mécanismes de régulation et de dégradation du complexe PCKS9-LDLR permettra de mieux évaluer l’impact et l’efficacité des inhibiteurs de la protéine PCSK9.
Abstract : Cardiovascular disease is the leading cause of global mortality, responsible for one third of global deaths, according to the latest statistics from World Health Organization. Hypercholesterolemia, characterized by increased plasma low-density lipoprotein (LDL) cholesterol, is a major determinant of cardiovascular disease risk. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a critical role in cholesterol homeostasis by regulating LDL receptor (LDLR) protein levels. PCSK9 binds to the LDLR and promotes its internalization and degradation in late endosomal/lysosomal compartments. Inhibition of PCSK9 action on LDLR has emerged as a novel therapeutic target for hypercholesterolemia and the prevention of cardiovascular disease. Annexin A2 (AnxA2) was reported as an endogenous extracellular inhibitor of PCSK9 activity upon cell-surface LDLR degradation and mechanisms of PCSK9’s regulation by AnxA2. However, its role on PCSK9 regulation still need better characterization in hepatocellular carcinoma cell lines. Moreover, many evidences suggest the presence of additional unknown interaction partners involve in the LDLR regulation and degradation mediated by PCSK9. These unknown partners could regulate the internalization and trafficking of the PCSK9-LDLR complex to lysosomes. The objectives of this thesis are to better define the role and impact of AnxA2 on PCSK9 and to identify novel PCSK9 interacting partners that participate and regulate the PCSK9-LDLR complex formation and degradation. We demonstrated that PCSK9 inhibition by extracellular AnxA2 occurs via its interaction with the M1+M2 modules of PCSK9’s C-terminal region. Most importantly, we revealed a new role of intracellular AnxA2 in the reduction of PCSK9 protein levels via a translational mechanism. Our results suggest a translational repression from the binding of AnxA2 to PCSK9’s mRNA. Also, we successfully identified a novel and functional interaction between glypican-3 (GPC3) and PCSK9. We demonstrated the extracellular GPC3 interaction with PCSK9 and the intracellular GPC3 with both PCSK9 and LDLR in human hepatocellular carcinoma cell lines HepG2 and Huh7. Our studies revealed that extracellular GPC3 can act as an endogenous competitive binding partner of PCSK9 to the LDLR, and hence reducing its activity towards LDLR degradation. The continued understanding of PCSK9 interactions is critical, from a mechanistic point of view as well as from the optimization of therapeutic interventions.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secreted glycoprotein that promotes degradation of low-density lipoprotein receptors. Gain- and loss-of-function variants of PCSK9 cause hypercholesterolemia and hypocholesterolemia, respectively. Although it has been a decade since the discovery of PCSK9, its effect in terms of global protein changes and interactions still require further understanding. This study provided a global outlook at the protein changes caused by PCSK9 and its variants in human hepatic HUH7 cell line. First, a proteomics-based method for protein subcellular distribution analysis has been developed. Second, through secretome analyses, six apolipoproteins and six proteins involved in the coagulation pathway were found with >2-fold changes between wild type PCSK9 and its variants. Third, through secreted interactome analyses, a list of 159 PCSK9 interactor candidates was identified. Two interacting proteins, FASN and PSMD2, were validated and demonstrated with dynamic interacting patterns between PCSK9 and its variants.

In vitro studies have shown that the major membrane phospholipid phosphatidylcholine (PC) can positively influence the incorporation of cholesterol in lipid membranes. The influence of PC on the cellular trafficking of LDL-derived free cholesterol was investigated. Sterol regulatory-defective (SRD)-4 cells are Chinese hamster ovary (CHO)-derived fibroblasts that display vastly elevated rates for the synthesis and catabolism of PC. SRD-4 cells harbor two known gene mutations: a mutation in the functional allele for SCAP, resulting in defective feedback suppression of cholesterol biosynthesis; and a loss-of-function mutation in the functional allele for acyl-CoA:cholesterol acyl transferase (ACAT), an endoplasmic reticulum (ER)-localized enzyme that esterifies free cholesterol. Incubation of SRD-4 cells with 50 µg/ml low density lipoprotein (LDL) for 18 h resulted in lysosomal accumulation of free cholesterol as revealed by filipin staining. This accumulation was not evident following LDL treatment of parental CHO7 cells, and was blunted in SRD-2 cells that express a constitutively-active form of SREBP-2 and overproduce cholesterol but have functional ACAT activity. Treatment of SRD-2 cells with LDL in the presence of an ACAT inhibitor 58-035 resulted in robust lysosomal cholesterol accumulation that was reversible upon drug washout, supporting that cholesterol trafficking in cholesterol-loaded cells is dependent on ACAT activity and, more specifically, ER free cholesterol levels. Lysosomal accumulation of LDL-derived cholesterol was prevented in SRD-4 cells supplemented with lyso-PC (50 µM), a substrate for PC synthesis through the reacylation pathway, and also in cells treated with bromoenol lactone (BEL), an inhibitor of phospholipase A2 implicated in bulk PC turnover. In a counter study, lysosomal LDL-derived cholesterol accumulation was induced in parental CHO-7 cells using R-propranolol, which inhibits the conversion of phosphatidic acid to diacylglycerol (DAG), a substrate in the CDP-choline pathway. This blockage was also relieved through co-treatment with lyso-PC. These studies support that PC to free cholesterol ratios in downstream organellar membranes can influence cholesterol trafficking out of lysosomal compartments in cholesterol-loaded cells.

Elevated plasma cholesterol is a risk factor for cardiovascular disease. Proprotein convertase subtilisin/kexin type 9 (PCSK9) hinders the uptake of low-density lipoprotein cholesterol (LDL-c) by mediating degradation of LDL receptors (LDLRs) in the liver. Gain-of-function (GOF) mutations in PCSK9 cause familial hypercholesterolemia (FH). In normolipidemic human plasma, 30-40% of PCSK9 is bound to LDL particles, and this association with LDL inhibits PCSK9’s ability to mediate LDLR degradation in cultured cells. To further investigate the physiological relevance of this interaction, we analyzed natural GOF mutations in PCSK9 and assessed their effects in vitro on LDL binding, LDLR binding and LDLR degradation. Our results indicate that several GOF mutations severely inhibit LDL binding compared to wild type (WT) PCSK9, and only modestly affect LDLR affinity and LDLR degradation. These findings shed light on the potential physiological relevance of the PCSK9-LDL interaction, which may have an inhibitory effect on PCSK9 activity in vivo.

Moderate consumption of red wine has been widely associated with reduced cardiovascular risk, mainly due to its composition in phenolic compounds with antioxidant activity, such as trans-resveratrol. Our aim was to compare the effect of red wine vs trans-resveratrol consumption on the prevention and regression of atherosclerosis in LDLr (-/-) mice. This study consisted of two protocols: \"PREVENTION\" (PREV) and \"REGRESSION\" (REGR). Both protocols included four groups: red wine (WINE), dealcoholized red wine (EXT), trans-resveratrol (RESV), and control (CONT). In PREV protocol, animals received a normal diet for 8 weeks and then switched to an atherogenic diet for the following 8 weeks, while the opposite was performed during REGR protocol. Animals that received atherogenic diet after an initial period on a normal diet (PREV) gained more body weight (39.25 ± 2.30%) than the opposite (29.27 ± 1.91%, p=0.0013), suggesting an interaction between age and weight gain. Trans-resveratrol showed the highest hypocholesterolemic effect in PREV protocol, reducing total cholesterol, LDL-C and VLDL-C, but also HDL-C. The supplementation with trans-resveratrol and dealcoholized red wine changed the fatty acids profile in the liver in both protocols, leading to an increase of MDA concentrations and SOD activity in PREV protocol. All three forms of supplementation altered biomarkers of oxidative stress and lipidemia but presented no effect on the prevention or regression of fatty streaks. These results suggest that the cardiovascular protection associated with the \"French Paradox\" may be a result of synergistic effects between wine and the Mediterranean diet.
O consumo moderado de vinho tinto tem sido amplamente associado à redução do risco cardiovascular, principalmente devido à sua composição em compostos fenólicos com atividade antioxidante, como o trans-resveratrol. Nosso objetivo foi o de comparar o efeito do consumo de vinho tinto vs trans-resveratrol na prevenção e regressão da aterosclerose em camundongos LDLr (-/-). Este estudo consistiu em dois protocolos: \"PREVENÇÃO\" (PREV) e \"REGRESSÃO\" (REGR). Ambos os protocolos incluíram quatro grupos: vinho tinto (WINE), vinho tinto sem álcool (EXT), transresveratrol (RESV) e controle (CONT). No protocolo PREV, os animais receberam uma dieta normal durante 8 semanas e trocaram para uma dieta aterogênica durante as 8 semanas seguintes, enquanto o oposto foi realizado no protocolo REGR. Os animais que receberam dieta aterogênica após um período inicial em dieta normal (PREV) ganharam mais peso corporal (39.25 ± 2.30%) do que o oposto (29.27 ± 1.91%, p=0.0013), sugerindo uma interação entre idade e ganho de peso. O trans-resveratrol mostrou efeito hipocolesterolêmico mais elevado no protocolo PREV, reduzindo colesterol total, LDL-C e VLDL-C, mas também o HDL-C. A suplementação com trans-resveratrol e vinho tinto sem álcool alterou o perfil de ácidos graxos do fígado em ambos os protocolos, levando a um aumento das concentrações de MDA e da atividade da SOD no protocolo PREV. Todas as três formas de suplementação alteraram biomarcadores do estresse oxidativo e lipidemia, mas não apresentaram efeito sobre a prevenção ou regressão de estrias gordurosas. Esses resultados sugerem que a proteção cardiovascular associada ao \"Paradoxo francês\" pode ser resultado de efeitos sinérgicos entre o vinho e a dieta mediterrânea.

Introdução: Os dados epidemiológicos e experimentais têm mostrado efeitos adversos da exposição pré e pós natal ao material particulado (MP2,5) sobre a saúde fetal e adulto. Entretanto, poucos estudos abordaram a toxicidade fetal da exposição gestacional à poluição do ar ambiental, bem como efeitos a longo prazo de adversos da exposição pré-natal sobre o desenvolvimento pós-natal e maturação de vários sistemas de órgãos. Objetivos: O objetivo deste estudo foi determinar se a exposição pré-natal e / ou pós-natal ao material particulado, influencia o desenvolvimento pulmonar e resposta vascular pulmonar em um modelo de camundongo suscetível a aterosclerose (LDLr-/- camundongos knockout). Métodos: Camundongos LDLr-/- foram expostos durante a gestação ao ar filtrado (AF) ou ar poluído (AC). Após o período de desmame, os filhotes foram subdivididos e novos quatro grupos foram formados de acordo com a exposição gestacional ou a exposição pós natal contínua no ar poluído. Atingindo a idade de 3 meses, esses grupos foram novamente subdivididos, formando um total de 8 grupos e uma dieta hipercolesterolêmica foi introduzida. Os seguintes parâmetros foram analisados: desfechos gestacionais, dosagem de colesterol total (CT) e triglicerídeos (TG) do fígado, avaliação de citocinas no LBA, e avaliação imunohistoquímica da resposta vascular pulmonar . Resultados: Nos grupos que receberam dieta hipercolesterolêmica (DH) os níveis de colesterol apresentaram-se aumentados (p=0,002); A expressão da IL6 no LBA mostrou-se elevada (p=0,01) somente no grupo que não foi exposto a poluição em nunhum período da vida e recebeu dieta postnatalmente. Diferenças significativas também foram observadas na expressão pulmonar vascular dos seguintes imunomarcadores: endotelina (p=0,05); ENOS (p=0,04); IL1? (p=0,005); INOS (p=0,002); ISOP (p=0,001); NOX2 (0,01) e ICAM (0,04) quando comparados ao grupo controle. O volume pulmonar total também se mostra alterado em decorrência do tratamento. Assim, conclui-se que a resposta do desenvolvimento pulmonar à exposição gestacional à poluição particulada do ar pode ser evidenciada mais tarde durante a vida adulta e agir como um fator modulador de insultos pós-natal devido à exposição a poluição do ar e a uma dieta hipercolesterolemica em individuos predispostos aterosclerose
Epidemiological and experimental data have shown adverse effects of gestational and post natal exposure to ambient particulate matter (PM) on the fetal and adult health. However, few studies addressed the fetal toxicity of gestational exposure to environmental air pollution as well as long-term adverse consequences of prenatal exposure on postnatal development and maturation of several organ systems. The aim of this study was to determine if prenatal and/or postnatal exposure to concentrated ambient particles influences lung development and pulmonary vascular response in an atherosclerosis susceptible mouse model (LDLr-/- knockout mice). LDLr-/- mice were exposed during the pregnancy to either filter (AF) or polluted air (CAP). After weaning period, pups were subdivided and new 4 groups formed according to gestational and continuous or not post natal exposure to air pollution. Reaching the age of 3 months these groups were again subdivided and a hypercholesterolemic (HC) diet introduced and a total of 8 groups were formed. Then the following parameters were analyzed: evaluation of the offspring outcomes, assessment of airway responsiveness, evaluation of cytokines in BALF, dosage of total cholesterol (TC) and triglycerides (TG) in the liver and pulmonary vascular response by immunohistochemistry. Results: Animals that received HC diet presented higher levels of cholesterol (p=0.002) when compared to those animals that received normal diet. Expression of IL-6 was only increased in the groups of mice exposed not exposed to particulate air pollution and that received the HC diet (p=0.01). Significant differences were also observed in vascular expression of immunomarkers in the lung endothelin (p=0.05); ENOS (p=0.04); IL1? (p=0.005); INOS (p=0.002); ISOP (p=0.001); NOX2 (0.01) e ICAM (0.04). Total lung volume was also different, there was an increase in those animals receiving a HC diet. In conclusion, the response of the lung development to gestational exposure to particulate air pollution can be evidenced later in life and act as a modulator factor for postnatal insults due to exposures to particulate air pollution and hypercholesterolemic diet in individual predisposed to atherosclerosis

L’adénocarcinome pancréatique (ADKP) est l’un des cinq cancers les plus mortels avec un taux de survie à 5 ans de 8,2% et une médiane de survie de 6 mois. En raison de l’absence de symptômes précoces et de traitements efficaces, 85% des patients sont diagnostiqués à un stade avancé de la maladie. La détermination du profil métabolique de l’ADKP, que nous avons précédemment défini, a mis en exergue leur forte dépendance au cholestérol satisfaite en augmentant l'internalisation des lipoprotéines de faible densité (LDL), via les récepteurs aux LDL (LDLR) qui sont sur-représentés à la surface des cellules tumorales d’ADKP. Par conséquent, le LDLR constitue une voie prometteuse par laquelle les agents cytotoxiques et/ou d'imagerie seraient spécifiquement délivrés à l’ADKP.Nous avons créé des cellules tumorales pancréatiques Ldlr+/+ et Ldlr-/-, originellement issues d’ADKP de souris KIC (LSL-KRasG12D ; Ink4a/Arffl/fl ; Pdx1-Cre) et un conjugué fluorescent ciblant le LDLR (Fc(A680)-VH4127). In vitro, nous avons montré que ce conjugué cible spécifiquement le LDLR et qu’il est internalisé et adressé aux lysosomes, comme les LDL. Ensuite, nous avons montré que ce conjugué permet de discriminer les ADKP Ldlr+/+ sous-cutanés des autres tissus sains (pancréas, foie et glandes surrénales). Enfin, des résultats similaires ont été obtenus chez les souris KIC, présentant fidèlement les caractéristiques des ADKP humains, et injectées avec le conjugué Fc(A680)-VH4127. Ainsi, l'utilisation en clinique de ce conjugué améliorerait 1/ le diagnostic de l’ADKP (marges de résection, volume tumoral) et 2 / le suivi de la réponse thérapeutique et la détection des récidives chez les patients opérés
Pancreatic adenocarcinoma (PDAC) is one of the five deadliest cancers, with a 5-year survival rate of 8.2% and a median survival of 6 months. Due to lack of early symptoms and effective treatments, 85% of the patients have an advanced disease at the time of diagnosis. In our previous work, aiming to decipher the metabolic reprogramming of PDAC, we showed its high dependence on cholesterol which it satisfies by increasing the low-density lipoprotein (LDL) internalization, through over-represented LDL receptors (LDLR) on pancreatic tumor cell surface. Therefore, LDLR could be a promising route for tumor-targeted delivery of cytotoxic and/or imaging agents. In this study, we generated Ldlr+/+ and Ldlr-/- pancreatic tumor cells derived from spontaneous PDAC mice model (KIC mice: LSL-KRasG12D ; Ink4a/Arffl/fl ; Pdx1-Cre) and used fluorescent labelled-vector cargo conjugate targeting LDLR extracellular domain (Fc(A680)-VH4127). In vitro, we showed that the conjugate specifically targets LDLR and is internalized and addressed to lysosomes, as the LDLR natural ligand. Then, we demonstrated that this conjugate specifically targets subcutaneous Ldlr+/+ pancreatic tumors and not healthy tissues (pancreas, liver, adrenal glands). Finally, similar results were obtained in KIC mice, faithfully presenting human PDAC features, injected with Fc(A680)-VH4127 conjugate. Hence, using this LDLR-targeting conjugate in clinic could improve 1/ PDAC diagnosis (resection margins, tumor volume) and thus increase the number of patients that could benefit from curative surgery and 2/ therapeutic response monitoring and recurrence detection in operated PDAC patients

La proprotéine convertase subtilisine/kexine de type 9 (PCSK9) régule la concentration des récepteurs des lipoprotéines de basse densité (LDLR) au niveau de la membrane cellulaire et par conséquent le taux de LDL-cholestérol dans le système vasculaire. PCSK9 est donc une cible essentielle dans le traitement des maladies cardiovasculaires (MCV). A ce jour, les anticorps monoclonaux anti-PCSK9 associés aux statines est la seule thérapie disponible ciblant PCSK9 en dépit des risques d’immunogénicité, une administration sous-cutanée contraignante et un coût élevé. Néanmoins, de petits peptides possédant des structures tridimensionnelles très stables se sont avérés être des inhibiteurs prometteurs de l’interaction entre PCSK9 et le LDLR induisant une augmentation significative de l’absorption du LDL dans les cellules. A partir de ces séquences, nous avons synthétisé des peptides stabilisés par des agrafes, avec un patch poly-lysine (technologie SIP) à l’extrémité C-terminale mais également des séquences chimériques afin de développer des analogues très actifs et résistants à la protéolyse. Nous avons obtenu des composés mille fois plus affins pour PCSK9 que le peptide de référence Pep2-8, capables de rétablir l’absorption du LDL dans les cellules pour de très faibles concentrations (IC50 = 175 nM). Les structures tridimensionnelles des composés clés ont été étudiées par dichroïsme circulaire (CD) et résonance magnétique nucléaire (RMN) afin d’étudier leurs relations structure-activité
Proprotein convertase subtilisin/kexin type 9 (PCSK9) has been identified as a regulator of low density lipoprotein receptor (LDLR) on the cell membrane and therefore plays a major role in cardiovascular diseases (CVD). To date, only monoclonal antibodies (mAbs) to PCSK9 are used associated with statins in therapies, despite a potential immunogenicity, a restrictive mode of administration and a high cost. Beside, small peptides with discrete three-dimensional structures were found to inhibit the interaction between PCSK9 and the LDLR, increasing the LDL-uptake. Starting from these sequences, we used various strategies incorporating staples and/or C-terminal lysine patches (SIP technology), synthesizing chimeric sequences to develop highly potent compounds resistant to enzymatic degradation. We obtained derivatives that have a 1000-fold stronger affinity than the parent peptide with high biological activities (IC50 = 175 nM). The three-dimensional structures of key compounds were extensively studied by circular dichroim (CD) and nuclear magnetic resonance (NMR) to investigate their structure-activity relationship

Orientador: Otavio Rizzi Coelho
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
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Resumo: A aterosclerose é caracterizada pelo recrutamento de monócitos e linfócitos para a parede do vaso. O efeito desencadeador deste processo é o acúmulo de partículas de LDL minimamente oxidadas, as quais estimulam as células endoteliais a produzirem moléculas pró-inflamatórias. Em adição à LDL oxidada, vários outros fatores modulam a inflamação tais como forças hemodinâmicas, hormônios sexuais e infecção. O objetivo deste estudo foi demonstrar o efeito anti-aterogênico do DMA, 6,7-Dimetoxi-4-N-(3¿-N¿,N¿-dimetil)fenilaminoquinazolina, em camundongos LDLr-/- . Este efeito pode ser relacionado com a propriedade anti-inflamatória do composto estudado, por evidências de que o mesmo aumenta a biodisponibilidade de adenosina nos tecidos pela inibição da adenosina quinase. Nossos resultados mostraram que o DMA administrado via oral, tanto no tratamento preventivo, quanto no tratamento de lesões pré estabelecidas, em camundongos LDLr-/- alimentados com dieta hipercolesterolêmica (1,25% colesterol e 0,5% ácido cólico) diminui o tamanho das placas ateroscleróticas em 67% e 52%, respectivamente, em relação ao grupo controle que recebeu veículo. Esses dados foram obtidos através da planimetria das lesões ateroscleróticas na base da artéria aorta com a coloroção Oil Red O específica para lipídios. A dieta hipercolesterolêmica (HC) por 15 e 30 dias reduziu o triglicéride sérico, medido pelo sistema de cromatografia líquida, em cerca de 50% sendo que o tratamento com DMA cancelou esta redução. A dieta HC por 15 e 30 dias aumentou o colesterol sérico, em cerca de 2 vezes nos camundongos LDLr-/-. Camundongos tratados com DMA e dieta HC apresentaram níveis de colesterol total maiores do que o grupo alimentado somente com dieta HC. Dados revelaram que este aumento foi devido ao maior nível de HDL circulante nos camundongos tratados com o composto DMA. Todos os camundongos em tratamento, tanto com DMA quanto com veículo, apresentaram redução do peso corporal em relação ao grupo de camundongos alimentados com dieta hipercolesterolêmica (HC)
Abstract: Atherosclerosis is characterized by the recruitment of monocytes and lymphocytes to the artery wall. A triggering event for this process is the accumulation of minimmally oxidized LDL, which stimulates the overlying endothelial cells to produce a number of pro-inflammatory molecules, including hemodynamic forces, sex hormones and infection. We demonstrated that DMA, ,7-Dimethoxi-4-N-(3¿-N¿,N¿-dimethyl)phenilaminoquinazoline, have an anti-atherogenic effect in mice LDLr-/-. This effect could have a relationship with an anti-inflammatory property of adenosine in tissues, by the inhibition of adenosine kinase. Results showed that DMA administrated by oral via, as prevent treatment, as pre-established lesions, in mice LDLr-/- with hypercholesterolemic diet (1,25% cholesterol and 0,5% colic acid), decreases atherosclerotic lesions in 67% and 52% respectively in relation of the vehicle group. These data was obtained by planimmetric study of atherosclerotic lesions in the base of aortic arthery with Oil Red O especific for lipids. The hypercholesterolemic diet by 15 and 30 days, decreases serum tryglicerides in 50%, in the other way, the treatment with DMA cancelled this reduction. At the same time, HC diet by 15 and 30 days increases total cholesterol serum, in 2 times in mice LDLr-/-. Mice treatment with DMA and hypercholesterolemic diet showed serum cholesterol higher than the HC group (control). Results demonstrated that this increase have relationship with higher HDL serum level in mice treated with compound. All mice in treatment (DMA and Vehicle group) had the weight decreased.
Mestrado
Ciencias Basicas
Mestre em Clinica Medica

Orientadores: Antonio Carlos Boschiero, Helena Coutinho Franco de Oliveira
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Alterações no conteúdo de colesterol celular podem contribuir para o mau funcionamento das células-beta pancreáticas. Camundongos knockout para o receptor de LDL (LDLR-/-) possuem maior teor de colesterol nas ilhotas pancreáticas e secretam menos insulina em comparação a camundongos selvagens (WT). Neste estudo, investigamos a associação entre o conteúdo de colesterol, a secreção de insulina e a movimentação de cálcio citoplasmático nessas ilhotas. Além disso, analisamos o efeito da dieta rica em gordura (HFD) sobre a homeostasia glicêmica, secreção e ação da insulina nesses camundongos. Os resultados mostraram que a primeira e segunda fase de secreção de insulina assim como a movimentação de Ca2+, estimuladas por glicose, foram reduzidas nos LDLR-/-. Camundongos LDLR-/- também apresentaram menor conteúdo de proteínas envolvidas com a extrusão dos grânulos de insulina tais como: VAMP-2 e SNAP-25 (p<0,05). A remoção do excesso de colesterol pelo uso da metil-beta-ciclodextrina (M?CD) normalizou a secreção de insulina, estimulada por glicose (GSIS) ou tolbutamida, assim como a movimentação de cálcio estimulada por glicose. A remoção do colesterol das ilhotas WT com 0.1 e 1 mmol/L de M?CD reduziu a secreção bem como a movimentação de cálcio. No entanto, ilhotas incubadas com 10 mmol/L de M?CD apresentaram aumento significativo na secreção de insulina, apesar da redução na movimentação de cálcio. A dieta hiperlipídica (H) promoveu maior ganho de peso e acúmulo de gordura visceral nos camundongos LDLR-/-H em relação aos WTH. A dieta aumentou a glicemia tanto no jejum quanto alimentado, porém não houve alterações nas concentrações plasmáticas de insulina nos camundongos LDLR-/-H. Já nos camundongos WTH, a dieta causou aumento nas glicemias de jejum e alimentado bem como na insulinemia. A área sob a curva glicêmica durante o oGTT foi 30% maior nos camundongos LDLR-/-H. A GSIS não foi significativamente alterada pela dieta hiperlipídica em ambos os grupos. Camundongos LDLR-/- em dieta padrão apresentaram maior fosforilação do receptor de insulina (IR?) e da AKT em fígado e músculo. O conteúdo da enzima que degrada a insulina (IDE) se mostrou reduzido nos LDLR-/-. A dieta hiperlipídica reduziu a sinalização da insulina em fígado, músculo e tecido adiposo dos camundongos LDLR-/-H. Nos camundongos WTH essa dieta promoveu apenas uma redução na fosforilação do IR? no músculo. A análise conjunta dos resultados nos permitiu concluir que, tanto o aumento de colesterol verificado em ilhotas LDLR-/- quanto a diminuição excessiva do conteúdo de colesterol em ilhotas WT (tratadas com M?CD) alteram a movimentação de cálcio e conseqüentemente a secreção de insulina. A redução do colesterol nas ilhotas dos camundongos LDLR-/- corrigiu a redução da secreção de insulina, apesar das concentrações reduzidas de VAMP-2 e SNAP-25. Camundongos LDLR-/-, alimentados com dieta padrão, são mais sensíveis à insulina, provavelmente como um mecanismo adaptativo a menor secreção de insulina. No entanto, estas adaptações não são suficientes para manter a homeostase glicêmica visto que estes animais são intolerantes à glicose. Quando alimentados com dieta hiperlipídica, os LDLR-/-H se tornam resistentes à insulina provavelmente devido ao aumento do tecido adiposo visceral
Abstract: Changes in cellular cholesterol levels may contribute to beta cell dysfunction. Islets from LDL receptor knockout (LDLR-/-) possess higher cholesterol content and secrete less insulin than wild type (WT) mice. Here, we investigated the association between cholesterol content, insulin secretion and Ca2+ handling in these islets. In addition, we analyzed the effects of highfat- diet (HFD) on glucose homeostasis, insulin secretion and action in these mice. Both first and second phase of glucose-stimulated insulin secretion (GSIS) were lower in LDLR-/- compared with WT islets. This lower secretion was paralleled by impairment in Ca2+ handling in these islets. The contents of SNAP-25 and VAMP-2 proteins, which participate in the extrusion of the insulin containing granules, were reduced in LDLR-/- compared with WT islets. Removal of the excess of cholesterol from LDLR-/- islets (Methyl-?-cyclodextrine, M?CD) normalized glucose- and tolbutamide-induced insulin release. Glucose-stimulated Ca2+ handling was also normalized in cholesterol-depleted LDLR-/- islets. Cholesterol removal from WT islets by 0.1 and 1.0 mmol/L M?CD impaired both GSIS and Ca2+ handling. However, 10 mmol/L M?CD markedly increased insulin secretion induced by glucose or tolbutamide in WT islets, despite a significant reduction in Ca2+ handling. The HFD promoted higher body weight gain and visceral fat pad depot in LDLR-/-H than in WTH. LDLR-/-H mice showed fasted and fed glucose levels significantly higher whereas no changes in fasted plasma insulin levels were observed. WTH mice also showed an increase in fasted and fed glucose levels, but a higher fasted plasma insulin level (p<0.05) was noticed. The area under the curve of the oGTT in LDLR-/-H, but not in WTH, was increased (30%) by HFD. GSIS was not significantly altered by HFD in both groups. LDLR-/- mice showed higher IR? and AKT phosphorylation in liver and skeletal muscle. Insulin degrading enzyme (IDE) protein content was lower in liver of LDLR-/-. The HFD reduced insulin signaling in liver, skeletal muscle and adipose tissue in LDLR-/-H. In WTH the HFD reduced only the IR? phosphorylation in muscle. In conclusion, our results indicate that abnormal high (LDLR-/- islets) or low (WT islets treated with M?CD) cholesterol contents alter both GSIS and Ca2+ handling. Normalization of islet cholesterol content improved Ca2+ handling and insulin secretion in LDLR-/- islets, despite the lower expression of SNAP-25 and VAMP-2. LDLR-/- mice, fed a chow diet, are more sensitive to insulin probably due adaptive mechanisms that compensate the low insulin secretion. However, these changes are not sufficient to promote glucose homeostasis since these mice were glucose intolerants. When fed a high-fat diet, they became also insulin resistant probably due to an increase in the mass of the visceral adipose tissue
Doutorado
Fisiologia
Doutor em Biologia Funcional e Molecular

A homeostase do colesterol é mediada por proteínas envolvidas na absorção (NPC1L1), regulação (SREBP1, SREBP2, SCAP), síntese (HMGCR) e remoção plasmática (LDLR). Os fármacos inibidores da síntese (vastatinas) e absorção (ezetimiba) do colesterol são potentes agentes hipocolesterolemiantes. Alterações em vários genes têm sido associadas a diferenças na resposta a diversos agentes terapêuticos. Com a finalidade de estudar os efeitos de hipolipemiantes e polimorfismos sobre a expressão dos genes HMGCR, LDLR, SREBF1a, SREBF2, SCAP e NPC1L1, foram selecionados 25 indivíduos com hipercolesterolemia familial (HF), 72 com hipercolesterolemia não familial (HNF) e 125 indivíduos normolipidêmicos e sem doença cardiovascular (NL). Os indivíduos HF foram tratados com sinvastatina (40 mg/dia/4 sem) combinada ou não com ezetimiba (10 mg/dia/4sem) e os HNF foram tratados com atorvastatina (10 mg/dia/4sem). Amostras de sangue foram obtidas antes e após o tratamento para a extração de DNA e RNA e analise do perfil lipídico sérico. A expressão de mRNA dos genes SREBF1a, SREBF2, SCAP, HMGCR, LDLR e NPC1L1 em células mononucleares do sangue periférico (CMSP) foi determinada por RT-PCR em tempo real empregando-se o gene da GAPD como controle endógeno. Os polimorfismos SREBF1a 36delG, SREBF2 G1784C e SCAP A2386G foram determinados por PCR-RFLP. Os indivíduos HF apresentaram maior expressão de mRNA dos genes NPC1L1, HMGCR e LDLR que os grupos HNF e NL (p<0,05). O efeito da atorvastatina sobre a expressão dos genes estudados parece depender da expressão basal nos indivíduos HNF. A variação da expressão após o tratamento com atorvastatina nos pacientes do grupo HNF esteve correlacionada nos genes: SREBF1a e SREBF2; SREBF1a e SCAP; SREBF1a e LDLR; SREBF2 e SCAP; SREBF2 e LDLR; HMGCR e LDLR. O tratamento com sinvastatina e ezetimiba não modificou o padrão de expressão dos genes estudados no grupo HF. Os polimorfismos SREBF2 G1784C e SCAP A2386G parecem estar relacionados com diminuição da expressão de mRNA após o tratamento com atorvastatina. Foi observado que os portadores do genótipo GG do polimorfismo SREBF2 G1784C apresentaram maiores concentrações séricas de colesterol total e LDL-C após o tratamento com atorvastatina. O polimorfismo SCAP A2386G parece estar associado com maiores concentrações de apoB em pacientes do grupo HNF antes do tratamento com atorvastatina. Os resultados são sugestivos que os genes HMGCR, LDLR e NPC1L1 são regulados diferentemente de acordo com o estado metabólico do indivíduo e a taxa de expressão de mRNA é influenciada pelos polimorfismos SREBF2 G1784C e SCAP A2386G após o tratamento com atorvastatina
The regulation of cholesterol is mediated by proteins involved in the absorption (NPC1L1), regulation (SREBP1, SREBP2, SCAP), synthesis (HMGCR) and removal of plasma cholesterol (LDLR). Potent hypocholesterolemic agents inhibit cholesterol synthesis (statins) and its absortion (ezetimibe). Changes in several genes have been associated to different responses to various therapeutic agents. In order to evaluate the association between genes involved in the metabolism of cholesterol and their response to lipid lowering drugs, patients with familial (FH, n = 25) and non familial hypercholesterolemia (NHF, n = 72) were selected. Additionally, 125 normolipidemic individuals and without cardiovascular disease were selected (NL). The HF group were treated with simvastatin (40 mg/day/4 weeks) combined or not with ezetimibe (10 mg/day/4weeks). The NHF group were treated with atorvastatin (10 mg/day/4weeks). Blood samples were obtained prior to and following treatment for extraction of DNA and RNA, and serum lipid profile analysis. The mRNA expression of SREBF1a, SREBF2, SCAP, HMGCR, LDLR, and NPC1L1 genes was determined by real time RT-PCR using the GAPD gene as endogenous control. The polymorphisms SREBF1a-36delG, SREBF2 G1784C, and SCAP A2386G were determined by PCR-RFLP. Individuals with HF showed higher expression of mRNA of genes NPC1L1, HMGCR and LDLR when compared with HNF and NL groups (p <0.05). The effect of atorvastatin on the gene expression seems to depend on the baseline expression in HNF subjects. The change of expression after treatment with atorvastatin in group HNF was correlated as followed: SREBF1a and SREBF2; SREBF1a and SCAP; SREBF1a and LDLR; SREBF2 and SCAP; SREBF2 and LDLR; HMGCR and LDLR. Treatment with simvastatin and ezetimibe did not change the gene-expression profile in HF group. The polymorphisms SREBF2 G1784C, and SCAP A2386G appear to be related to a decreased expression of mRNA after treatment with atorvastatin. HNF group Carriers of GG genotype of SREBF2 G1784C polymorphism had higher serum concentrations of total cholesterol and LDL-C after therapy. The SCAP A2386G polymorphism seems to be associated with higher concentrations of apoB in patients from HNF group prior to treatment with atorvastatin. The results suggest that the HMGCR, LDLR and NPC1L1 genes are regulated according to the metabolic status of the individual, and the expression rate of mRNA is influenced by SREBF2 G1784C and SCAP A2386G polymorphisms after atorvastatin therapy.

Introdução: as gorduras interesterificadas, ricas em ácidos graxos saturados, vêm sendo utilizadas pela indústria alimentícia em substituição aos ácidos graxos trans. Os principais ácidos graxos saturados empregados no processo de interesterificação são o palmítico e o esteárico, os quais podem, respectivamente, apresentar efeitos deletérios ou serem neutros, do ponto de vista cardiovascular e metabólico. A quantidade de ácido esteárico na dieta é menor em comparação ao palmítico, e não está elucidada a implicação de seu alto consumo. O propósito deste estudo foi avaliar o efeito das gorduras interesterificadas contendo ácido palmítico ou ácido esteárico sobre as principais vias de sinalização envolvidas no metabolismo do tecido hepático e adiposo. Métodos: camundongos machos LDLr-KO foram alimentados durante 16 semanas com dieta hiperlipídica (40% de energia em forma de gordura) contendo maior concentração de poli-insaturados (POLI), palmítico (PALM), palmítico interesterificado (PALM INTER), esteárico (ESTEAR) ou esteárico interesterificado (ESTEAR INTER). Determinaram-se a composição corporal, conteúdo de gordura no fígado, concentração plasmática de colesterol, triglicérides, glicose e insulina. A expressão de genes envolvidos no metabolismo lipídico e vias inflamatórias no tecido adiposo visceral e hepático foi determinada por RT-qPCR. Além disso, a síntese de proteínas e proteínas fosforiladas foi medida por Imunnoblotting. O infiltrado de células inflamatórias no tecido hepático e histologia do tecido adiposo, bem como o conteúdo de colágeno do fígado, foram determinados por coloração com eosina e hematoxilina e Sirius Red, respectivamente. Resultados: o processo de interesterificação não alterou parâmetros bioquímicos plasmáticos e as quantidades de CT e TG no tecido hepático. No entanto, ambas as gorduras interesterificadas induziram maior conteúdo de colágeno no fígado e fosforilação de JNK. Adicionalmente, o grupo ESTEAR INTER desenvolveu NASH, associada a maior infiltrado de neutrófilos. Por outro lado, PALM INTER induziu maior expansão do tecido adiposo, juntamente com hipertrofia de adipócitos, condições associadas à ativação da via de sinalização \"upstream\" do NFkB, observada para a fosforilação de IKK, o que contribuiu para maior teor de TNFalfa. Conclusão: as gorduras interesterificadas enriquecidas com ácido palmítico induziram fibrose hepática, bem como a expansão do tecido adiposo, com hipertrofia dos adipócitos; e as gorduras contendo ácido esteárico induziram NASH em camundongos LDLr-KO
Background: interesterified fats, rich in saturated fatty acids, have been used by the food industry as a substitute for trans fatty acids. The main saturated fatty acids used in the interesterification process are palmitic and stearic, which may, respectively, have deleterious effects or be cardiovascular and metabolic neutral. Objetive: to evaluate the effect of interesterified fats containing palmitic or stearic acids on signaling pathways involved in the hepatic and adipose tissue lipid metabolism. Methods: Weaning male LDLr-KO mice were fed a high-fat diet (40% energy as fat) containing polyunsaturated (PUFA), palmitic (PALM), palmitic interesterified (PALM INTER), stearic (STEAR) or stearic interesterified (STEAR INTER) fats for 16 weeks. Body composition, liver fat content, total plasma cholesterol, triglycerides, glucose and insulin concentrations were determined. Gene expression involved in lipid metabolism and inflammation process in liver and white adipose tissue was determined by quantitative RT-PCR. Furthermore, amount of proteins and activated proteins were measured by Western blot. Hepatic and adipose tissue inflammatory cells infiltration as well as liver collagen content were determined by eosin and hematoxylin and Sirius Red staining, respectively. Results: Interesterified process did not alter plasma biochemical parameters and amounts of TC and TG in hepatic tissue. However, both interesterified fats brought on a higher liver collagen content and JNK phosphorylation. Additionally, STEAR INTER group developed NASH associated with a higher neutrophil infiltration. On the other hand, PALM INTER induced a higher adipose tissue expansion together with the enlargement of adipocytes, conditions associated with the activation of upstream NFkB signaling pathway as observed for IKK phosphorylation, contributing to higher TNFalpha protein content. Conclusions: Interesterified fats containing stearic acid induced NASH and enriched with palmitic acid trigger on steatosis with fibrosis as well as hypertrophy and inflammatory signaling activation in the adipose tissue in LDLr-KO mice

Proprotein Convertase Subtilisin/Kexin 9 (PCSK9) is the latest member of the PCSK enzyme family that is structurally related to the bacterial subtilisin and the yeast kexin. It plays a major role in the regulation of cholesterol by degrading low-density lipoprotein receptor (LDLR) responsible for the endocytosis of LDL-cholesterol. Thus, there is a great deal of research interest in the development of PCSK9 functional inhibitors which may have potential applications as therapeutic agents for lowering plasma LDL-cholesterol and the associated risk of cardiovascular disease. PCSK9 degrades LDLR by first binding to form a complex and then rerouting to the lysosomal compartment leading to its degradation. In addition it was shown that following the autocatalytic cleavage, the prodomain of PCSK9 remains strongly attached to the mature PCSK9 via its catalytic domain. Owing to these findings, we proposed that selected peptides from hPCSK9 pro and catalytic domains are likely to affect the LDLR binding. Using human hepatic HepG2 and Huh7 cells we showed that the acidic N-terminal and the mid-basic segments of the prodomain enhanced the LDLR protein level significantly, without altering the PCSK9 protein level. The physiologically relevant phoshpho-Ser47 peptide decreased the LDLR protein level suggesting that Ser47-phosphorylation leads to a gain of functional activity of PCSK9. Addition of recombinant PCSK9 to the culture medium decreased the LDLR protein level that was restored by the addition of PCSK931-40, 31-60 or 91-120 peptides. Two catalytic domain peptides PCSK9181-200 and PCSK9368-390 decreased LDLR content confirming their interactions with LDLR. Our study concludes that specific peptides from the pro- and catalytic domains of PCSK9 can regulate LDLR and may be useful for development of novel therapeutics for cholesterol regulation.

Orientadores: Helena Coutinho Franco de Oliveira, Antonio Carlos Boschero
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Neste trabalho, investigamos se a hipercolesterolemia primária per se, independente de dieta rica em gordura, afeta a homeostase glicêmica e a secreção de insulina estimulada por vários secretagogos em animais knockout para o receptor de LDL (LDLR-/-). Além disso, investigamos os possíveis mecanismos envolvidos na liberação deste hormônio neste modelo animal. Podemos resumir nossos achados da seguinte maneira: camundongos LDLR-/- apresentam hiperglicemia pós-prandial, hipoinsulinemia, intolerância à glicose e sensibilidade periférica à insulina normal. Nós demonstramos que, as alterações na homeostase glicêmica ocorrem em parte, por uma diminuição da sensibilidade das ilhotas à glicose. A secreção de insulina é normal na presença de baixa concentração de glicose, entretanto na presença de 11,1 mmol/l, as ilhotas de animais LDLR-/- liberam menos insulina que as ilhotas controles. A secreção de insulina estimulada por outros secretagogos metabolizáveis (leucina e KIC) também está reduzida nas ilhotas dos animais knockout. O conteúdo total de insulina e DNA são similares entre os grupos, sugerindo que as alterações na secreção de insulina não ocorrem devido a diferenças no tamanho e/ou número de células b. Observamos uma redução na primeira e segunda fase de secreção de insulina estimulada por 11,1 mmol/l de glicose. A oxidação da glicose está reduzida, enquanto a metabolização da leucina está aumentada. Quando adicionamos agentes despolarizantes (KCl, Arginina e Tolbutamida), observamos uma redução da secreção de insulina tanto em concentrações basais quanto estimulatórias de glicose. Na presença de 11,1 mmol/l de glicose e carbacol (agonista colinérgico) ou PMA (ativador da proteína-quinase C), a secreção de insulina foi semelhante entre os grupos LDLR- /- e controles. Entretanto, quando estimulamos a secreção com forskolin ou IBMX, que aumentam os níveis de AMPc, observamos redução na liberação de insulina pelas ilhotas dos animais LDLR-/- em comparação com os controles. A expressão protéica da fosfolipase C (PLCb2) está aumentada enquanto que a expressão da proteína-quinase A (PKA) está reduzida nas ilhotas dos animais LDLR-/-. Assim, observamos que camundongos LDLR-/- apresentam alterações na homeostase glicêmica independente de dieta rica em gordura, provocada por redução na secreção de insulina devido, em parte à redução do metabolismo da glicose, bem como, redução na expressão da PKA
Abstract: In this work, we investigated whether primary hyperlipidemia per se, independently of a high-fat diet, affects glycemia and insulin secretion stimulated by several secretagogues in hypercholesterolemic low-density lipoprotein receptor knockout mice (LDLR-/-). In addition, we investigated the possible mechanisms involved in the release of this hormone. We found that, besides higher total cholesterol and triglyceride plasma concentrations, glucose plasma levels were increased and insulin decreased in LDLR-/- compared to the wild type (WT) mice. LDLR-/- mice presented impaired glucose tolerance, but normal whole body insulin sensitivity. In addition, we also demonstrate that the main cause of the impaired glucose homeostasis is a reduced pancreatic islet insulin secretion ability following fuel secretagogue stimuli. LDLR-/- mice have impaired insulin secretion in response to glucose without alterations in the pancreatic total insulin and DNA contents. These findings support the idea that the decreased response to glucose cannot be explained by differences islet size or number of beta cells, but it is probably caused by a defect in the secretory process. Glucose oxidation was 30% lower and L-leucine oxidation 60% higher in LDLR-/- islets than in WT islets. At basal (2.8 mmol/l) and stimulatory (11.1 mmol/l) glucose concentrations, the insulin secretion rates induced by depolarizing agents such as KCl, L-arginine and tolbutamide were significantly reduced in LDLR-/- when compared with WT islets. Insulin secretion induced by the PKA activators, forskolin and IBMX, in the presence of 11.1 mmol/l glucose, was lower in LDLR-/- islets, and it was normalized in the presence of the PKC pathway activators, carbachol and PMA. Western blotting analysis showed that phospholipase C-b2 expression was increased and PKA-a decreased in LDLR-/- compared with WT islets. In conclusion, we demonstrate that genetic hypercholesterolemia, due to complete deficiency of LDLR, impairs the beta cell insulin secretion, leading to hyperglycemia without affecting body insulin sensitivity. The lower insulin secretion in LDLR-/- mice islets may be explained by reduced glucose metabolism and expression of PKA
Doutorado
Fisiologia
Doutor em Biologia Funcional e Molecular

Orientador: José Angelo Camilli
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Introdução: O tecido ósseo pode sofrer alterações em suas propriedades bioquímicas, morfológicas, bioquímicas e biomecânicas sob a influência de determinadas doenças. Níveis elevados de colesterol e hiperlipidemia podem causar alterações no osso, comprometendo a osteogênese e resistência mecânica. A sinvastatina é um medicamento do grupo de estatinas mais comumente utilizado para o tratamento d hiperlipidemia, reduzindo o nível de colesterol. Além disso, estudos com estatinas têm demonstrado bons resultados na prevenção e tratamento da osteoporose. Objetivos: Avaliar o efeito da hiperlipidemia e da utilização de sinvastatina sobre as propriedades biomecânicas, a estrutura do osso cortical e trabecular e osteogênese em camundongos LDLr(-/-) e selvagens. Métodos: Neste estudo foram utilizados camundongos do tipo selvagem (C57BL6) (Grupo W) e camundongos homozigotos para a ausência do gene receptor LDL (LDLr-/-) (Grupo L), todos do sexo masculino com 3 meses de idade. Os animais foram divididos em dois grupos experimentais, que foram subdivididos em quatro grupos de 12 animais cada: Experimento I (grupo W - ração padrão; Grupo WH - dieta hiperlipídica; Grupo L - ração padrão e Grupo LH - dieta hiperlipídica) e Experimento II tratados com sinvastatina (S) (Grupo WS - ração padrão; Grupo WHS - dieta hiperlipídica; Grupo LS - ração padrão e Grupo LHS - dieta hiperlipídica). Após 15 dias de experimentação um defeito ósseo de 3mm de diâmetro foi produzida cirurgicamente no osso parietal direito em cada animal. No final de 60 dias de experimentação os animais foram sacrificados. O sangue foi coletado e os fêmures e o osso parietal direito foram retirados para estudo histológico e mecânico. Resultados: Os dados obtidos neste estudo originou três artigos. O primeiro artigo "Efeitos da hiperlipidemia sobre as propriedades biomecânicas e morfológicas do fêmur de camundongos LDLr(-/-)" aceito para publicação no Journal of Bone and Mineral Metabolism, o segundo "Efeitos da sinvastatina sobre as propriedades morfométricas e mecânicas no fêmur de camundongos" formatado para submissão ao Journal of Orthopaedic Research e o terceiro artigo "Efeitos da hiperlipidemia e sinvastatina na reparação óssea de defeitos na calvária de camundongos LDLr-/-" esta sendo preparado para a publicação. Conclusão: A dieta hiperlipídica causa alterações na integridade óssea e que o uso da sinvastatina foi eficaz para preservar as propriedades biomecânicas do fêmur nos animais tratados com dieta comercial, no entanto, seu efeito sobre o tecido ósseo pode ser comprometido pela ingestão de uma dieta rica em gorduras. A osteogênese foi restrita nos camundongos LDLr-/-, principalmente nos grupos alimentados com dieta rica em gorduras
Abstract: Introduction: The bone tissue can suffer alterations in their biochemical morphological and biomechanical properties under influence of certain diseases. High levels of cholesterol and hyperlipidemia can cause changes in the bone, compromising osteogenesis and mechanical strength. The simvastatin is a drug of the statins group most commonly used for the treatment of hyperlipidemia, reducing the cholesterol level. Additionally, studies with statins have demonstrated good result in the prevention and treatment of osteoporosis. Objectives: Evaluate the effect of hyperlipidemia and the use of simvastatin on the biomechanical properties, structure of cortical and trabecular bone and osteogeneses in LDLr(-/-) and wild-type mice. Methods: In this study were used wild-type (W) mice (C57BL6) and homozygous mice for the absence of the LDL receptor gene LDLr-/- (L), all male with 3 months of age. The animals were divided into two experimental groups that were subdivided into four groups of 12 animals each: Experiment I (Group W - standard ration; Group WH - high-fat diet; Group L - standard ration; Group LH - high-fat diet) and Experiment II with simvastatin (S) (Group WS - standard ration; Group WHS - high-fat diet; Group LS - standard ration; Group LHS - high-fat diet). After 15 days of experimentation a bone defect measuring 3mm in diameter was surgically produced in the right parietal bone in each animal. At the end of 60 days of experimentation the animals were euthanatized. Blood was collected and the femurs and the right parietal bone were removed for mechanical and histological study. Results: The data obtained in this study originated three articles. The first article "Effect of hyperlipidemia on femoral biomechanics and morphology in LDLr-/- mice" was accepted for publication in the Journal of Bone and Mineral Metabolism, the second "Effects of simvastatin on morphometric and mechanical properties in the femur of mice" was submitted to Journal of Orthopaedic Research and the third article "Effect of hyperlipidemia and simvastatin on bone repair of the calvaria of the LDLr-/- mice" is being prepared for publication. Conclusions: The high-fat diet caused alteration in bone integrity and the treatment with simvastatin was effective in preserving the biomechanical properties and structure of the femur in the animals treated with low-fat diet, however, its effect on bone tissue can be compromised by a high-fat diet. Osteogenesis was reduced in LDLr-/- mice, especially in the high-fat diet groups
Doutorado
Anatomia
Doutor em Biologia Celular e Estrutural

O quimioterápico 5-FU pode causar efeitos indesejáveis como a mucosite que aumenta os mediadores inflamatórios sistêmicos e locais e também a mielossupressão que resulta em leucopenia e anemia. Duas doenças inflamatórias crônicas, aterosclerose e obesidade, são influenciadas por células imunes, especialmente macrófagos. Por isso, a quimioterapia pode interferir nas suas evoluções, negativamente pela inflamação gerada pela mucosite ou positivamente pela redução da infiltração de macrófagos devido à mielossupressão. Nosso objetivo foi avaliar o efeito do 5-FU no tecido adiposo e na aterogênese. Animais LDLr-/- foram divididos nos grupos controle e 5-FU, recebendo dieta ocidental e duas aplicações de placebo ou 5-FU (150 mg/kg) respectivamente, no primeiro e no vigésimo segundo dia experimental. O sacrifício ocorreu três semanas após a segunda aplicação. Os resultados mostram que animais tratados com 5-FU perderam peso após as aplicações, que foi recuperado nas últimas semanas. O perfil lipídico foi semelhante entre os grupos, exceto pela redução de triglicérides no grupo 5-FU que ainda apresentou redução da gordura visceral e da infiltração de macrófagos neste tecido. O mielograma e leucograma mostraram resultados similares nos dois grupos, exceto pela redução de células eritrocitárias no grupo 5-FU. Apesar do grupo 5-FU apresentar discreta mucosite ao fim do experimento, a infiltração de macrófagos e neutrófilos no intestino foi semelhante entre os grupos. No entanto, a infiltração de eosinófilos foi inferior no grupo 5-FU. Na válvula aórtica, o tratamento com 5-FU reduziu a lesão aterosclerótica, obstrução luminal e a migração de macrófagos. Concluimos que o tratamento com 5-FU reduz a gordura visceral e a lesão aterosclerótica, associadas com diminuição de macrófagos nestes tecidos
O quimioterápico 5-FU pode causar efeitos indesejáveis como a mucosite que aumenta os mediadores inflamatórios sistêmicos e locais e também a mielossupressão que resulta em leucopenia e anemia. Duas doenças inflamatórias crônicas, aterosclerose e obesidade, são influenciadas por células imunes, especialmente macrófagos. Por isso, a quimioterapia pode interferir nas suas evoluções, negativamente pela inflamação gerada pela mucosite ou positivamente pela redução da infiltração de macrófagos devido à mielossupressão. Nosso objetivo foi avaliar o efeito do 5-FU no tecido adiposo e na aterogênese. Animais LDLr-/- foram divididos nos grupos controle e 5-FU, recebendo dieta ocidental e duas aplicações de placebo ou 5-FU (150 mg/kg) respectivamente, no primeiro e no vigésimo segundo dia experimental. O sacrifício ocorreu três semanas após a segunda aplicação. Os resultados mostram que animais tratados com 5-FU perderam peso após as aplicações, que foi recuperado nas últimas semanas. O perfil lipídico foi semelhante entre os grupos, exceto pela redução de triglicérides no grupo 5-FU que ainda apresentou redução da gordura visceral e da infiltração de macrófagos neste tecido. O mielograma e leucograma mostraram resultados similares nos dois grupos, exceto pela redução de células eritrocitárias no grupo 5-FU. Apesar do grupo 5-FU apresentar discreta mucosite ao fim do experimento, a infiltração de macrófagos e neutrófilos no intestino foi semelhante entre os grupos. No entanto, a infiltração de eosinófilos foi inferior no grupo 5-FU. Na válvula aórtica, o tratamento com 5-FU reduziu a lesão aterosclerótica, obstrução luminal e a migração de macrófagos. Concluimos que o tratamento com 5-FU reduz a gordura visceral e a lesão aterosclerótica, associadas com diminuição de macrófagos nestes tecidos

Orientadores: Marta Helena Krieger, Regina Celia Spadari
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Os objetivos do presente estudo são investigar e comparar o efeito do nitrosotiol doador de NO (SNAC) e do doador de NO-/HNO (Sal de Angelis) na estrutura e função do miocárdio sob processo aterogênico precoce induzido pela dieta em camundongos com deleção gênica do receptor de LDL (LDLr-/-). Os dados obtidos possibilitam avaliar a eficácia destas espécies químicas, bem como os mecanismos de ação envolvidos nos efeitos preventivos promovidos pelo sistema NO/NOS e pela via HNO, na hipertrofia ventricular esquerda, neste modelo animal. O papel dos adrenoceptores beta no controle da função cardíaca destes camundongos LDLr-/- também foi avaliado. A deleção gênica do receptor de LDL resultou em déficit contrátil cardíaco, sem alteração na homogeneidade da população miocárdica de adrenoceptores ß1, mas quando associada à dieta hiperlipídica induziu participação de adrenoceptores ß2, com conseqüente alteração da sensibilidade aos efeitos inotrópico e cronotrópico da isoprenalina. O tratamento com SNAC e Sal de Angelis (SA) preveniu o aumento da sensibilidade à isoprenalina, provavelmente ao induzir o acoplamento dos adrenoceptores ß 2 com a proteína Gi. Além disso, o SA foi capaz de corrigir o déficit contrátil do miocárdio. Camundongos LDLr-/- também apresentaram hipertensão, a qual foi prevenida pelo tratamento com SNAC. Quando a deleção gênica estava associada à dieta hiperlipídica, os camundongos apresentaram hipertensão e hipertrofia ventricular esquerda. O SNAC e o SA previniram a hipertrofia, mas não a hipertensão. Concluímos que camundongos com deleção gênica do receptor de LDL, alimentados com dieta hiperlipídica são um modelo interessante de alterações cardíacas e hemodinâmicas, especialmente quando enfocamos alterações das respostas dos adrenoceptores beta adrenérgicos, e que compostos doadores de NO e seus congêneres podem se tornar uma alternativa para prevenir tais alterações
Abstract: The aim of this study is to analyze and to compare the effects of a nitrosothiol NO donnor (SNAC) and of a NO-/HNO donor (Angelis Salt, AS) on the structure and functioning of myocardium under atherogenic process induced by a hyperlipic diet in LDL receptor knockout mice (LDLr-/-). The role played by the ß adrenoceptor subtypes in the control of the cardiac function of LDLr-/- mice has also been analysed. LDLr-/- mice exhibited a contractile deficit in the myocardium, with no alteration in the response to isoprenaline, which is mediated by a homogeneous population of ß1 adrenoceptors. However, when it was associated with a hyperlipidic diet, ß2 adrenoceptors participate in the inotropic and chronotropic responses to isoprenaline, causing an alteration on tissue sensitivity to the agonist. LDLr-/- knockout mice treatment with SNAC or AS avoided the atria supersensitivity to isoprenaline by inducing ß2 adrenoceptors coupling to Gi protein. Moreover, AS but not SNAC was able to recover the atria contractile performance. LDLr-/- mice also presented hypertension that it was prevented by the SNAC treatment. Hypertension was accompanied by ventricular hypertrophy when the gene deletion was associated with a hyperlipidic diet. SNAC or AS treatment prevented the hypertrophy, but not the hypertension. We concluded that LDLr-/- mice fed with a hyperlipidic diet are useful models for the study of haemodynamic and cardiac diseases related to a hypercholesterolemic profile, mostly when the focus is to investigate the participation of the adrenoceptors in the involved processes, and that NO donnors or similar compounds may be an alternative tool to prevent such alterations
Mestrado
Fisiologia
Mestre em Biologia Funcional e Molecular

Une personne sur cinq dans la population générale présente des niveaux plasmatiques élevés en lipoprotéine (a) [Lp(a)], une lipoprotéine extrêmement athérogène qui ressemble aux LDL. Les études physiopathologiques, épidémiologiques, et génétiques démontrent que lorsque la concentration sanguine en Lp(a) dépasse 125 nmol/L, la survenue d’événements cardiovasculaires augmente très fortement. La différence structurale majeure entre Lp(a) et LDL est que la Lp(a) contient une protéine caractéristique supplémentaire, l’apo(a), de taille très variable car elle contient entre 1 et 40 répétitions du domaine Kringle IV2 (KIV2). La taille de l’apo(a) est inversement corrélée aux concentrations plasmatiques en Lp(a). Outre l’apo(a), l’apoE et PCSK9 sont les deux seules autres protéines circulantes connues pour moduler les taux de Lp(a). L’objet de mes travaux de thèse a été de déterminer comment la taille de l’apo(a), le polymorphisme de l’apoE et l’inhibition pharmacologique de PCSK9 régulent les niveaux de Lp(a). Nous avons d’abord développé une approche méthodologique originale de spectrométrie de masse pour doser les apolipoprotéines, déterminer leurs polymorphismes, et en évaluer les flux métaboliques. Nous avons également mis au point une technique de séparation résolutive des différentes isoformes de l’apo(a) sur gel d’agarose. Nous montrons par spectrométrie de masse que l’apoE présente sur les VLDL gouverne la production (synthèse/assemblage) de la Lp(a). Par ailleurs, nous avons établi que les patients hypercholestérolémiques familiaux porteurs de l’isoforme E2 de l’apoE présentent des concentrations de Lp(a) plus faibles comparativement aux porteurs des isoformes E3 et E4, ce qui leur confère un taux de récidive pour les événements vasculaires réduit. Enfin, nous avons démontré chez des patients à haut risque cardiovasculaire que la réponse à un traitement par inhibiteurs de PCSK9 en termes de réduction de la Lp(a), est proportionnelle à la taille de l’apo(a). Nous avons également observé que le traitement par aphérèse d’un patient présentant des niveaux très élevés en Lp(a), le protège contre une récidive d’infarctus du myocarde. L’ensemble de mes résultats nous a permis de déterminer les modalités physiologiques par lesquelles la taille de l’apo(a) et le polymorphisme de l’apoE modulent les niveaux circulants de cette lipoprotéine extrêmement athérogène. Les thérapies actuelles (inhibiteurs de PCSK9, aphérèse) restent cependant insuffisantes pour une prise en charge optimale des patients avec une Lp(a) élevée
One in five individuals in the population displays elevated circulating levels of lipoprotein (a) [Lp(a)], a highly atherogenic lipoprotein resembling LDL. Pathophysiological, epidemiological and genetic studies demonstrate that circulating Lp(a) levels above 125 nmol/L are associated with a sharp increase in cardiovascular events rate.The major structural difference between Lp(a) and LDL is that Lp(a) contains a signature protein, apo(a), extremely polymorphic in size as it contains 1 to more than 40 Kringle IV2 (KIV2) domains. The size of apo(a) is inversely correlated with the circulating levels of Lp(a). Besides apo(a), apoE and PCSK9 are the only other plasma proteins known to modulate Lp(a) levels. The aims of my PhD project were to assess how the size of apo(a), the polymorphism of apoE and the pharmacological inhibition of PCSK9 govern Lp(a) plasma concentrations. First, we have developed a robust methodological approach to quantitatively assay apolipoproteins, assess their polymorphisms and evaluate their metabolic fluxes by mass spectrometry. In addition, we have set up a resolutive separation technique allowing the investigation of distinct apo(a) isoforms on agarose gels. We then showed using mass spectrometry that apoE specifically present on VLDL impacts on Lp(a) production, synthesis and/or assembly. In addition, we clearly established that familial hypercholesterolemic patients specifically carrying the apoE2 isoform display reduced Lp(a) plasma levels and are thereby less prone to recurrent cardiovascular events compared with apoE3 or E4 carriers. Finally, we demonstrate that the response to PCSK9 inhibitor treatments of patients at high cardiovascular risk in terms of Lp(a) lowering is proportional to the size of apo(a). We also observed that apheresis procedures performed on a patient with extreme Lp(a) plasma levels reduce his risk of undergoing recurrent myocardial infarction. Taken together, my PhD results allowed us to decipher the physiological modalities by which apo(a) size and apoE polymorphism modulate the circulating levels of this extremely atherogenic lipoprotein species. The therapies currently available (PCSK9 inhibitors, plasmapheresis) remain however clearly insufficient to treat patients with elevated Lp(a)

PCSK9 (proprotein convertase subtilisin/kexin type 9) and glucose metabolism: which connection? Background: PCSK9 (proprotein convertase subtilisin/kexin type 9), is a protein, mainly synthesized and secreted by the liver, which binds to specific target proteins and escorts them towards lysosomes for degradation. The best defined activity of PCSK9 is its ability to modulate the hepatic uptake of LDL cholesterol (LDL-C), by enhancing the intracellular degradation of the LDL receptor (LDLR). In humans, several mutations in PCSK9 gene were described, both “gain-of-function” mutations associated to hypercholesterolemia and “loss of function” mutations linked to low LDL-C levels [1]. These findings suggest PCSK9 inhibitors as a promising class of drugs for the treatment of patients with severe hypercholesterolemia or at very high cardiovascular risk. However, some gaps regarding the potential role of PCSK9 in targeting the LDLR in organs other than the liver are still open. Indeed, the LDLR is abundantly expressed in pancreatic β-cells, where it plays a key role in the uptake of plasma LDL particles [2]. Therefore, further investigations are needed to better clarify the physiological role of PCSK9, also in light of its pharmacological targeting. Methods: WT, PCSK9 KO, LDLR KO, PCSK9/LDLR DKO, albumin (Alb)Cre+/PCSK9LoxP/LoxP (liver selective PCSK9 KO mice) and AlbCre-/PCSK9LoxP/LoxP mice were fed a HFD (High Fat Diet – 45% Kcal fat) or SFD (Standard Fat Diet – 10% Kcal fat) for 12 or 20 weeks. GTT, ITT, insulin and C-peptide plasma levels, pancreas morphology and cholesterol accumulation in pancreatic islets were studied in the different animal models. Results: Glucose clearance was significantly impaired in PCSK9 KO mice fed a SFD or a HFD for 20 weeks compared to WT animals, with both diet. On the contrary, insulin sensitivity was not affected as both animals showed a similar decrease in plasma glucose levels following insulin injection (ITT). Plasma insulin and C-peptide levels were reduced in PCSK9 KO mice compared to WT and accordingly fasting and refeeding experiments showed increased plasma glucose but reduced insulin levels in PCSK9 KO compared to controls. A detailed analysis of pancreas morphology of PCSK9 KO mice vs WT littermates revealed larger islets with increased accumulation of cholesteryl esters, paralleled by increased insulin intracellular levels. This phenotype was completely reverted in PCSK9/LDLR DKO mice implying the LDLR as the PCSK9 target responsible for the phenotype observed. Further studies in AlbCre+/PCSK9LoxP/LoxP, which lack detectable circulating PCSK9, also showed a complete recovery of the phenotype, thus indicating that circulating, liver-derived PCSK9 does not impact β-cells function and insulin secretion. Conclusion:The PCSK9/LDLR axis affects β-cells function and control insulin secretion. Our data indicate that this effect is independent of circulating PCSK9, and is probably related to local effects of PCSK9 suggesting the possibility that anti-PCSK9 antibodies or liver specific therapies, such as siRNAs, might have a limited impact on LDLR expression in pancreas and β-cells dysfunction.

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FACEPE
O sobrepeso e a obesidade têm sido identificados como os fatores de risco mais importantes para muitas doenças, incluindo doenças cardiovasculares, diabetes tipo 2 e distúrbios lipídicos como a doença do fígado gorduroso não- alcoólica (NAFLD). Atualmente, a NAFLD é considerada como a manifestação hepática da síndrome metabólica, sendo uma das doenças hepáticas mais prevalentes em todo o mundo. Evidências crescentes sugerem que o AMPK e SREBP são reguladores críticos do metabolismo de lipídios no fígado. As tiazolidinadionas (TZDs) são comumente utilizadas para o tratamento de diabetes tipo 2 e outras condições que ofereçam resistência a insulina como a NAFLD. No presente estudo, foi avaliada a atividade biológica do derivado tiazolidínico (LPSF/GQ-02) sobre a via metabólica de lipídios na patogênese da NAFLD. Foram utilizados camundongos deficientes do receptor de LDL (LDLr-/-) dividido em três grupos: 1- Dieta hipercalórica (HFD); 2- HFD + Pioglitazona (20 mg/kg/dia); 3- HFD+LPSF/GQ-02 (30mg/kg/dia). O experimento foi realizado por 12 semanas sendo que nas ultimas 4 semanas as drogas em estudo (PIO e LPSF/GQ-02) foram administradas via gavagem. Os resultados obtidos indicaram que a LPSF/GQ-02 foi eficaz em melhorar a arquitetura hepática diminuindo a acumulação de gordura no fígado, através da inibição da via da lipogênese (LXR/SREBP-1C/ACC/FAS), bem como através da ativação da via lipolítica (AMPK/FoxO1/ATGL). Estes resultados sugerem uma ação direta da LPSF/GQ-02 sobre o metabolismo lipídico e consequentemente na esteatose hepática, devido à diminuição de gordura nos hepatócitos por meio da inativação da via de síntese de lipídios e aumento da β- oxidação dos ácidos graxos e lipólise. Sendo assim, esses dados apoiam os resultados anteriormente publicado pelo Laboratório de Ultraestrutura do Aggeu Magalhães, que mostraram a propriedade hipolipemiante da LPSF/GQ-02, ao reduzir o acúmulo de triglicerídeo no fígado, bem como confirma o potencial desta TZD para o tratamento na NAFLD.
Overweight and obesity have been identified as the more important risk factors for many diseases, including cardiovascular disease, type 2 diabetes and lipid disorders as the disease. Nonalcoholic fatty liver disease (NAFLD). Actually, NAFLD is considered as the hepatic manifestation of metabolic syndrome is one of the most prevalent liver disease worldwide. Growing evidences suggests that AMPK and SREBP are critical regulators of lipid metabolism in the liver. The thiazolidinediones (TZDs) are commonly used for the treatment of type 2 diabetes and other conditions that provide insulin resistance and NAFLD. In the present study, we evaluated the biological activity of LPSF / GQ-02 on the metabolic pathway of lipids in the pathogenesis of NAFLD. We used mice deficient in LDL receptor (LDLr - / -) divided into three groups: 1 hypercaloric diet (HFD); 2- HFD + pioglitazone (20 mg / kg / day); 3- HFD + LPSF / GQ-02 (30mg / kg / day). The experiment was conducted for 12 weeks and in the last four weeks the drugs were administered daily by gavage. The results indicated that LPSF / GQ-02 was effective in improving liver architecture by decreased the accumulation of fat in the liver, by inhibiting the lipogenic via (LXR / SREBP-1C / ACC / FAS), as well as activating the lipolytic pathway (AMPK / FoxO1 / ATGL). These results suggest a direct action of LPSF / GQ-02 on lipid metabolism in hepatic steatosis and, consequently, due to the decrease of fat in hepatocytes through the inactivation of lipid synthesis pathway and increase the β-oxidation of fatty acids and lipolysis. Thus, these data support the results previously published by Ultrastructure Laboratory Aggeu Magalhães, who showed lipid-lowering property of LPSF / QA-02 by reducing triglyceride accumulation in the liver, and confirms the potential of this TZD for treatment in NAFLD.

Com a introdução da terapia antirretroviral de alta potência (HAART), em 1996, tornou-se cada vez mais evidente que os pacientes infectados pelo HIV-1 têm um risco aumentado de desenvolver dislipidemia. A proposta deste estudo foi avaliar a associação entre o polimorfismo PvuII localizado no intron 15 do gene do receptor de lipoproteína de baixa densidade (LDLR) e as alterações no perfil lipídico dos pacientes infectados pelo HIV-1, submetidos ou não a HAART, pois não se tem conhecimento da avaliação deste polimorfismo nestes indivíduos. Foram avaliados 355 pacientes infectados pelo HIV-1. Destes, 100 (28,2%) eram virgens de tratamento e 255 (71,8%) foram tratados com HAART. O grupo controle consistiu de 116 indivíduos saudáveis. Os genótipos PvuII do LDLR foram identificados pelo método da PCR-RFLP. O alelo P2 inclui o sítio de restrição para a PvuII o que resulta em dois fragmentos: um de 200 pb e outro de 600 pb após a digestão, já o alelo P1 é identificado por um fragmento de 800 pb. As frequências dos genótipos P1P1, P1P2 e P2P2 do polimorfismo PvuII no intron 15 do LDLR obtidas nos pacientes e nos controles foram 52,4%, 39,1% e 8,5%; e 55,2%, 42,2% e 2.6%; respectivamente. Os pacientes (submetidos ou não ao HAART) apresentaram maior concentração sérica de triglicerídeos (TG) e menor colesterol de lipoproteína de alta densidade (HDL-C) do que os controles (p<0,0001). Os pacientes em uso de HAART apresentaram níveis mais elevados de TG (p<0,0001), colesterol total (p<0,0001) e colesterol de lipoproteína de baixa densidade (LDL-C, p=0,0003) do que aqueles virgens de HAART. A frequência dos pacientes com níveis de colesterol total ≥ 200 mg/dL, LDL-C ≥ 100 mg/dL e TG ≥ 150 mg/dL foi maior entre aqueles que usavam HAART (p<0,0001, p=0,0248 e p=0,0269, respectivamente). Quando os pacientes com HIV-1 foram categorizados de acordo com os níveis de HDL-C, a frequência de indivíduos com baixos níveis de HDL-C não diferiram entre os que estavam virgens de tratamento ou em tratamento com HAART (p=0,7375). No entanto, quando os valores de HDL-C foram avaliados de acordo com o polimorfismo PvuII no intron 15 do LDLR, a frequência de HDL-C ≥ 40 mg/dL para homens e ≥ 50 mg/dL para mulheres foi maior entre os portadores do genótipo P2P2 (p = 0,0415). Os resultados obtidos mostraram que a frequência de indivíduos com níveis aumentados de colesterol total, LDL-C e TG foi maior entre os pacientes infectados pelo HIV-1 em uso de HAART. Quando os valores de HDL-C foram avaliados de acordo com o polimorfismo PvuII no intron 15 do LDLR, a frequência de valores elevados de HDL-C foi maior entre os portadores do genótipo P2P2. Os resultados sugerem que a infecção pelo HIV-1 per se e o uso de HAART alteram o colesterol total, LDL-C e TG em pacientes infectados pelo HIV-1 independentemente do polimorfismo PvuII no intron 15 do LDLR; entretanto, os efeitos desses fatores no HDL-C podem ser atenuados em parte, pelo genótipo P2P2 deste polimorfismo.
The introduction of highly active antiretroviral therapy (HAART) in 1996 has become increasingly clear that HIV-1-infected patients exhibit an increased risk for developing dyslipidemia. The proposal of this study was to evaluate the association between the PvuII intron 15 polymorphism at the low-density lipoprotein receptor (LDLR) gene and the changes in lipid profile among the patients with HIV-1 infection submitted or not to HAART, since there is no knowledge of the evaluation of this polymorphism in these individuals. A total of 355 HIV-1-infected patients were analyzed. Of them, 100 (28.2%) were antiretroviral naïve and 255 (71.8%) were treat with HAART. The control group consisted of 116 healthy individuals. The PvuII LDLR genotypes were determined from the genomic DNA using PCR-RFLP methods. The P2 allele includes a restriction site for PvuII which results in two fragments: one of 200 bp and one of 600 bp after digestion, whereas the P1 allele is identified by one fragment with 800 bp. The frequencies of P1P1, P1P2, and P2P2 PvuII intron 15 LDLR genotypes obtained among the patients and healthy controls were 52.4%, 39.1%, and 8.5%; and 55.2%, 42.2%, and 2.6%; respectively. The patients (submitted or not to HAART) presented higher serum triglycerides (TG) and lower serum high-density lipoprotein cholesterol (HDL-C) concentration than controls (p<0.0001). The patients treated with HAART showed higher TG (p<0.0001), total cholesterol (p<0.0001), and low-density lipoprotein cholesterol (LDL-C, p=0.0003) than those without HAART. The frequency of patients with total cholesterol levels ≥ 200mg/dL, LDL-C levels ≥ 100mg/dL, and TG ≥ 150mg/dL was higher among those using HAART (p<0.0001, p=0.0248, and p=0.0269, respectively). When HIV-1 patients were categorized according to HDL-C values, the frequency of individuals with low HDL-C levels did not differ among the HIV-1 infected patients antiretroviral naïve or on HAART (p=0.7375). However, when the HDL-C values were evaluated according to LDLR PvuII intron 15 polymorphism, the frequency of HDL-C ≥ 40 mg/dL for men and ≥ 50 mg/dL for women was higher among those carrying the P2P2 genotype (p=0.0415). The results obtained showed that the frequency of individuals with increased total cholesterol, LDL-C, and TG was higher among the HIV-1 patients using HAART. When the HDL-C values were evaluated according to LDLR PvuII intron 15 polymorphism, the frequency of high HDL-C values was higher among those carrying the P2P2 genotype. The results underscore that the HIV-1 infection per se and the HAART change the total cholesterol, LDL-C and TG in HIV-1-infected patients independent of the LDLR PvuII intron 15 polymorphism; however, the effects of these factors on the HDL-C can be mitigated, in part, by the P2P2 genotype of this polymorphism.

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LDLr-/ - mice are spontaneously hyperlipidemic and resistant to the development of neointimal lesions. This study determined the influence of plasma levels of high density lipoprotein on cardiovascular inflammation, insulin resistance, and blood cell count in LDL (LDLr-/ -) receptor gene knockout mice. Three groups of 3-month-old male mice were used: Group WT, wild-type mice, Group S, LDLr-/ - mice fed a standard diet, Group HL, LDLr-/ - mice fed a hyperlipidic diet. After 15 days, blood was collected for analysis of plasma lipids, glucose, insulin, and hematological assays. The HOMA index was calculated to determine insulin resistance. The heart and aorta were removed and histologically processed. Heart sections were immunohistochemically processed with the anti-CD40L antibody to evaluate the inflammatory process. Artery sections were stained with hematoxylin-eosin and picrosirius red to assess morphological and morphometric changes. The S mice were resistant to inflammatory, had a low immunoreactivity to CD40L, high HDL plasma levels, and showed no insulin resistance, even with moderate hyperlipidemia in relation to WT. HL mice exhibited severe hyperlipidemia, increased immunoreactivity to CD40L, marked morphological alterations in the aorta wall, and insulin resistance, all associated with a decrease in HDL plasma levels in relation to S. The results showed a negative association between the plasma levels of high density lipoprotein and the total and differential leukocyte and platelet counts in the LDL receptor gene knockout mice. This ratio showed the important influence of the high density lipoprotein on the modulation of the immune and inflammatory response in dyslipidemias. Therefore, the evaluation of the blood cell count results, routinely correlated with the lipid plasma levels, can be promising in the prevention and prognosis of the severity of pathological conditions involving immune responses in dyslipidemias. The high HDL plasma level is a protective factor against the development of cardiovascular inflammation and insulin resistance in LDLr-/- mice, thus preventing the incidence of neointimal lesions.
Os camundongos LDLr-/- são hiperlipidêmicos espontâneos e resistentes ao desenvolvimento de lesões neointimais. O presente estudo teve como objetivo determinar a influência dos níveis plasmáticos de lipoproteína de alta densidade na inflamação cardiovascular, na resistência insulínica e no hemograma de camundongos knockout para gene do receptor de LDL (LDLr-/-). Foram utilizados 3 grupos experimentais de camundongos machos com 3 meses de idade: Grupo WT, camundongos selvagens; Grupo S, camundongos LDLr-/- que receberam ração padrão; Grupo HL, camundongos LDLr-/- que receberam ração hiperlipídica. Após 15 dias, o sangue foi coletado para análises plasmáticas dos lipídeos, glicose, insulina e para análises hematológicas. O índice de Homa foi calculado para determinar a resistência insulínica. O coração e aorta foram removidos e processados histologicamente. Cortes histológicos do coração foram processados imunoistoquimicamente com anticorpo anti-CD40L para avaliar processo inflamatório. Cortes histológicos das artérias foram corados com hematoxilina/eosina e picrosírius red para avaliar alterações morfológicas e morfométricas. Os camundongos S foram resistentes ao processo inflamatório, caracterizado por baixa imunorreatividade para o CD40L, com níveis plasmáticos de HDL elevados, e não desenvolveram resistência insulínica, mesmo com hiperlipidemia moderada em relação aos WT. Os camundongos HL apresentaram uma hiperlipidemia severa, aumento na imunorreatividade cardíaca para o CD40L, pronunciadas alterações morfológicas na parede da aorta e resistência insulínica, associadas a um decréscimo nos níveis plasmáticos do HDL em relação aos S. Os resultados mostraram uma associação negativa entre os níveis plasmáticos de lipoproteína de alta densidade e as contagens total e diferencial de leucócitos e plaquetas nos camundongos knockout para o gene do receptor de lipoproteína de baixa densidade. Essa relação demonstrou importante influência da lipoproteína de alta densidade na modulação da resposta imunológica e inflamatória na dislipidemia. Portanto, a avaliação dos resultados do hemograma correlacionada com os níveis plasmáticos de lipídeos, rotineiramente, pode ser promissora na prevenção e no prognóstico da severidade de quadros patológicos que envolvam respostas imunológicas nas dislipidemias. O nível plasmático elevado de HDL é o fator protetor contra o desenvolvimento de processos inflamatórios cardiovasculares e resistência insulínica nos camundongos LDLr-/-, impedindo o desenvolvimento das lesões neointimais.

Die autosomal-dominant vererbte Familiäre Hypercholesterinämie ist durch eine exzessive Erhöhung der LDL-Serumcholesterinspiegel gekennzeichnet und bedingt aufgrund einer prämaturen Atherosklerose den frühzeitigen Tod der Patienten. Da ursächlich ein defekter LDL-Rezeptor (LDL-R) zugrundeliegt, der durch Mutationen im Bereich des LDL-R-Gens hervorgerufen wird, kommt der Gentherapie als potentieller Behandlungsmöglichkeit ein besonderer Stellenwert zu. Diese Arbeit untersuchte den Einfluß einer Virusdosiseskalation auf Cholesterinsenkung und Langzeitexpression im adenoviral vermittelten LDL-R-Gentransferversuch im Kaninchenmodell. Hierfür wurden 7 Watanabe Heritable Hyperlipidemic Kaninchen, welche an einer vergleichbaren kongenitalen Hypercholesterinämie durch einen LDL-R-Defekt leiden, mit unterschiedlichen Dosierungen eines Adenovirus des Serotyps 5 therapiert, der die Gensequenz für den humanen LDL-R enthielt. Vor und nach Therapie wurden Bestimmungen der Serumcholesterinkonzentrationen und LDL-Stoffwechselkinetiken mit 125I-LDL sowie semiquantitative szintigraphische Auswertungen durch 111In-LDL-Scans durchgeführt. Hierbei mußte festgestellt werden, dass die adenoviral vermittelte transgene Expression des LDL-R durch die Bestimmung des Serumcholesterins nicht korrekt wiedergegeben wird. Denn zum einen konnte bei der Bestimmung des Serumcholesterins ein dosisabhängiger Effekt beobachtet werden, dieser zeigte sich bei den Stoffwechselkinetiken mit 125I-LDL und bei den Scanuntersuchungen mit 111-In-LDL jedoch nicht. Zum anderen kam es innerhalb von 12-18 Tagen nach Gentransfer zu einem Wiedererreichen der Serumcholesterinausgangswerte, wohingegen die in vivo-Stoffwechselkinetiken eine erhöhte Abbaurate radiomarkierter LDL und die Szintigraphie eine LDL-R-Expression über die gesamte Dauer des Experimentes von 120 Tagen belegten.
Familial hypercholesterolemia is an autosomal dominantly inherited disease characterized by an exzessive elevation of serum LDL cholesterol which leads to premature atherosclerosis and an early death of the patients. As the reason is a defective LDL receptor (LDLR) caused by mutations in the gene encoding LDLR, gene therapy plays an increasingly important role as a treatment possibility. This paper examined the influence of an escalation of the virus dose on the cholestorol reduction and long-term expression in the adenovirally mediated LDLR gene therapy experiment using a rabbit animal model. To facilitate this 7 Watanabe Heritable Hyperlipidemic rabbits, suffering from an equivalent congenital hypercholesterolemia due to a LDLR defect, were treated with different doses of a serotype 5 adenovirus which contained the gene sequence of the human LDLR. Pre and post gene therapy measurements of the serum cholesterol levels and kinetics of LDL metabolism with 125I-LDL were performed, as well as semiquantitative scintigraphic analysis of 111In-LDL scans. The finding was that the adenovirally mediated transgene expression of the LDLR was not correctly reflected by the measurement of the serum cholesterol levels. This was because of a dose dependant effect concerning the measurements of the serum LDL cholesterol levels, which did not appear regarding the kinetics of LDL metabolism with 125I-LDL and the scans with 111In-LDL. Moreover, the serum cholesterol levels reached their initial value within 12-18 days post gene transfer whilst the in vivo-kinetics of LDL metabolism showed an increased catabolic rate of radiolabeled LDL and the scintigraphy indicated a LDLR expression for the whole period of the experiment lasting 120 days.

La thérapie cellulaire pourrait représenter une alternative à la transplantation hépatique dans certaines pathologies comme les maladies métaboliques sévères. Toutefois, la pénurie de donneurs d’organes implique la nécessité de trouver de nouvelles sources de cellules hépatiques comme les cellules souches pluripotentes qui peuvent être amplifiées extensivement et différenciées en tout type cellulaire. Les cellules souches embryonnaires humaines (hESC) et les cellules souches pluripotentes induites humaines (hiPSC) générées à partir des cellules somatiques de patients puis différenciées en hépatocytes représentent une source potentielle d’hépatocytes. Ces cellules permettent en outre d’envisager la transplantation d’hépatocytes autologues génétiquement modifiés comme alternative à la transplantation hépatique pour le traitement de certaines maladies génétiques du foie. L’hypercholestérolémie familiale (HF) est une maladie autosomale dominante due à des mutations dans le gène codant le Récepteur aux Low Density Lipoproteins (RLDL) qui est à l’origine d’un taux élevé de cholestérol sanguin de patients HF. Les patients homozygotes doivent épurer leur sérum par LDL-aphérèse en moyenne deux fois par mois dès le plus jeune âge pour éviter les infarctus mortels survenant dès l’enfance. Les hépatocytes différenciées à partir des iPSC de patients et leur correction in vitro, permettent d'évaluer la faisabilité de la transplantation d'hépatocytes autologues génétiquement modifiés pour le traitement de l’hypercholestérolémie familiale.Au cours du développement du foie, des hépatocytes et des cholangiocytes, les deux types de cellules épithéliales hépatiques, dérivent de progéniteurs hépatiques bipotents (les hépatoblastes). Bien que les cholangiocytes formant les canaux biliaires intrahépatiques ne représentent qu'une petite fraction de la population cellulaire totale du foie (3%), ces cellules régulent activement la composition de la bile par réabsorption des acides biliaires, un processus qui est important dans des maladies choléstatiques du foie. Dans la première partie de cette étude nous avons mis au point une approche de différenciation des cellules souches pluripotentes (hESC et hiPSC) en cholangiocytes fonctionnels. Ces cellules serviront à la modélisation des maladies génétiques touchant les cholangiocytes formant des canaux biliaires. Dans la deuxième partie, nous avons généré des iPSC spécifiques de patients HF (HF-iPSC), différenciées en hépatocytes et corrigé le défaut phénotypique par transfert lentiviral de l’ADNc codant le LDLR dans les HF-iPSC
Cell therapy can be an alternative to liver transplantation in some cases such as severe metabolic diseases. However, the shortage of organ donors implies the need to find new sources of liver cells such as hepatocytes derived from pluripotent stem cells that can be amplified and differentiated extensively into any cell type. Human embryonic stem cells (hESC) and human induced pluripotent stem cells (hiPSC) generated from somatic cells of patients and then differentiated into hepatocytes represent a potential source of transplantable hepatocytes. These cells now make it possible to consider the transplantation of genetically modified autologous hepatocytes as an alternative to liver transplantation for the treatment of genetic diseases of the liver.Familial hypercholesterolemia (FH) is an autosomal dominant disorder caused by mutations in the gene encoding the receptor for Low Density Lipoproteins (LDLR), which is the cause of high blood cholesterol in these patients. Homozygous patients should purify their serum LDL-apheresis on average twice a month starting at a young age to avoid fatal myocardial infarction occurring in childhood.Human hepatocytes differentiated from patient’s induced pluripotent stem cells (iPSCs) allow assessing the feasibility to transplant genetically modified autologous hepatocytes as treatment of familial hypercholesterolemia.During the liver development, hepatocytes and cholangiocytes, the two types of hepatic epithelial cells, derive from bipotent hepatic progenitors (hepatoblasts). Although cholangiocytes, forming intrahepatic bile ducts, represent a small fraction of the total liver cell population (3%), they actively regulate bile composition by secretion and reabsorption of bile acids, a process that is important in cholestatic liver diseases. In the first part of this study we developed an approach to differentiate pluripotent stem cells (hESC and hiPSC) into functional cholangiocytes. These cells could be used for the modeling of genetic biliary diseases. In the second part, we generated FH patient specific iPSCs (HF-iPSC), differentiated them into hepatocytes and tried to correct the disease phenotype by lentiviral introduction of LDLR cDNA cassette in HF-iPSC

La barrière hémato-encéphalique (BHE) protège le système nerveux central (SNC) des fluctuations plasmatiques des molécules endogènes, mais aussi exogènes, et notamment des molécules à potentiel thérapeutique. L’imperméabilité de la BHE est compensée par la présence de mécanismes qui assurent le transport transendothélial des nutriments nécessaires au tissu nerveux, parmi lesquels la transcytose relayée par différents récepteurs. Dans le but d’améliorer le transfert d’agents thérapeutiques à travers la BHE, nous développons des « vecteurs » qui se lient à certains de ces récepteurs. Au cours de notre thèse, nous avons développé et optimisé des modèles in vitro de BHE et barrière sang-moelle épinière (BSME) syngéniques de rats et souris, basés sur la co-culture de cellules endothéliales microvasculaires (CEMs) cérébrales (CEMCs) ou spinales (CEMSs) et d'astrocytes. Parmi les récepteurs étudiés, nous montrons que le LDLR est exprimé à la membrane plasmique apicale des CEMCs et qu’il est impliqué dans la transcytose du LDL tout en évitant le compartiment lysosomal, confirmant l’intérêt de son ciblage dans nos approches. Nous montrons que nos vecteurs, conjugués à une molécule organique ou à un cargo protéique, sont endocytés par les CEMCs de façon LDLR-dépendante, évitent le compartiment lysosomal et franchissent la monocouche de CEMCs. Nous avons également mis en place des modèles in vitro de BHE et BSME enflammés, sachant que l’inflammation des CEMs est associée à de nombreuses pathologies du SNC. Ces modèles seront utiles pour évaluer des stratégies de vectorisation ciblant préférentiellement les structures du SNC en situation pathologique
The blood-brain barrier (BBB) protects the central nervous system (CNS) from plasma fluctuations of endogenous, but also exogenous molecules, including therapeutic molecules. The BBB’s restrictive properties are compensated by the presence of different mechanisms that provide transport of nutrients across the BBB, including transcytosis of endogenous ligands mediated by receptors. Our objective is to improve drug delivery across the BBB and we developed “vectors” that target different recpetors. During our thesis we developed and optimized cellular tools and approaches, in particular syngeneic in vitro models of the BBB and blood-spinal cord barrier (BSCB) from both rat and mouse, based on the co-culture of brain (BMECs) or spinal cord (SCMECs) microvascular endothelial cells (MECs) and astrocytes. Among the receptors we studied, we show that the LDL receptor (LDLR) is expressed at the apical plasma membrane of BMECs and confirmed that it is involved in transcytosis of LDL through the vesicular compartment, while avoiding the lysosomal compartment, further establishing its interest as a target receptor. We show that our vectors conjugated to an organic molecule or to a protein cargo are endocytosed by BMECs in a LDLR-dependent manner, avoid the lysosomal compartment and cross the BMEC monolayers. Finally, we developed BBB and BSCB in vitro models in inflammatory conditions, considering that MECs inflammation is associated with many CNS lesions and pathologies. These models will be useful to better understand the inflammatory processes of CNS endothelial cells and to evaluate vectorization strategies preferentially targeting CNS structures in pathological condition

L’Organització Mundial de la Salut (OMS) estima que fins a un 3% de la població mundial ha estat infectada pel virus de l’hepatitis C i és la causa més important d’hepatitis crònica, cirrosi i de malaltia hepàtica terminal, que finalment acaba conduint a un transplantament de fetge. La relació entre la variabilitat en la seqüència del virus de l’hepatitis C i el desenvolupament de la malaltia hepàtica és de tipus multifactorial. La infecció crònica causa fibrosi hepàtica, fet que es veu accelerat per mecanismes desconeguts en el cas de pacients coinfectats amb VIH. La progressió de la malaltia produïda pel VHC en pacients coinfectats, està influenciada no només per factors demogràfics, epidemiològics o pels antecedents clínics dels pacients, si no també per diferències genètiques entre els diferents virus i els hostes.

Tese de mestrado em Biologia Molecular e Genética, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016
As doenças cardiovasculares (DCV) afetam o funcionamento normal do coração e dos vasos sanguíneos. Existem vários tipos de doenças cardiovasculares, sendo as principais a doença das artérias coronárias e a doença das artérias do cérebro. A doença coronária é, maioritariamente, provocada por aterosclerose, uma doença progressiva e inflamatória que resulta na formação de placas ateroscleróticas. Agentes infeciosos ou concentrações elevadas de lipoproteínas de baixa densidade (LDL) no sangue podem levar ao aparecimento destas placas na parede interna das artérias impedindo a circulação sanguínea. As doenças cardiovasculares são uma das causas de morte mais comum no planeta. Fatores de risco como o uso de tabaco, obesidade, prática de exercício físico reduzida, consumo excessivo de álcool, diabetes, hipertensão, stress e dislipidémia aumentam a probabilidade de ocorrência prematura deste tipo de doenças. A dislipidémia é um dos mais importantes fatores de risco da aterosclerose, uma vez que se caracteriza por anomalias quantitativas ou qualitativas dos lípidos no sangue. A identificação de indivíduos em risco e o conhecimento da causa de hipercolesterolemia é de extrema importância para que estes indivíduos possam ser corretamente tratados evitando-se, assim, a morte devida a esta causa. A Hipercolesterolemia Familiar (FH) é uma doença autossómica dominante do metabolismo do colesterol. A FH é hereditária e resulta, maioritariamente, de mutações no gene do recetor das lipoproteínas de baixa densidade (LDLR) cuja função é a remoção do colesterol LDL do plasma, transportando-o para o fígado, onde é processado. Ficando esta função afetada, os níveis de colesterol LDL circulante, aumentam. Mutações noutros genes como o gene da apolipoproteína B-100 (APOB) e da pro-proteína convertase subtilisina/quexina tipo 9 (PCSK9) são também causa, embora menos frequente, desta doença. Alterações no gene da apolipoproteína E (APOE) afetam a afinidade com os recetores de lipoproteínas e, consequentemente, a remoção do colesterol do sangue, podendo também causar dislipidémia. A forma homozigótica da FH é rara e mais severa, mas a heterozigótica é comum embora sub-diagnosticada em muitas populações, nomeadamente na portuguesa. Estima-se que, na maioria dos países europeus, a prevalência destas duas formas seja 1/1000000 e 1/500 indivíduos, respetivamente. O colesterol total, na forma heterozigótica, varia entre 290 e 500 mg/dL (com LDL>190 mg/dl) e na forma homozigótica, habitualmente, encontra-se entre os 600 mg/dL e os 1000 mg/dL. O nível elevado de colesterol no plasma resulta, frequentemente, na formação de depósitos de colesterol nos tecidos extravasculares que, por vezes, podem ser facilmente identificados em indivíduos ainda jovens (abaixo dos 45 anos): xantelasmas, arco corneano e, mais difíceis de reconhecer mas mais específicos, os xantomas nos tendões. A presença de valores altos de colesterol LDL desde o nascimento, característico desta doença, leva a um incremento do risco de doença coronária prematura. Este fenótipo permite diferenciar a FH de outras causas de hipercolesterolemia, nomeadamente da hipercolesterolemia comum ou poligénica, embora nem sempre seja fácil essa diferenciação. Foram descritas, em todo o mundo, mais de 1700 mutações diferentes no gene LDLR. Contudo, grande parte destas não possuem estudos funcionais, o que impede o diagnóstico definitivo destes doentes. Em 1999 iniciou-se no Instituto Nacional de Saúde Dr. Ricardo Jorge o Estudo Português de Hipercolesterolemia Familiar. Este estudo tem como objetivos a pesquisa de alterações genéticas que possam confirmar o diagnóstico clínico de FH em indivíduos da população portuguesa e a determinação da prevalência e distribuição da FH em Portugal. Os casos índex são incluídos no estudo caso cumpram os critérios adaptados de Simon Broome. Estes critérios categorizam a FH como “definitiva” ou “possível”, sendo que a primeira se define, em adultos, por valores de colesterol total acima de 290 mg/dL ou de colesterol LDL acima de 190 mg/dL, e em crianças, até aos 16 anos de idade, por uma concentração de colesterol total cima de 260 mg/dL ou de colesterol LDL acima de 155 mg/dL, com presença de xantomas no doente ou num familiar de primeiro ou segundo grau ou ainda quando existe evidência genética de uma mutação num dos 3 genes que cause FH. O diagnóstico “possível” requer a presença de níveis de colesterol acima destes valores, valores totais de colesterol acima dos 290 mg/dL num familiar de primeiro ou segundo grau e história familiar ou enfarte do miocárdio antes dos 50 anos num familiar de segundo grau ou antes dos 60 anos num familiar de primeiro grau. Sempre que possível, após a identificação da possível alteração causadora de doença é feito o estudo funcional para as variantes de patogenicidade desconhecida, para que o diagnóstico seja o mais completo e definitivo possível, contribuindo para uma abordagem terapêutica mais personalizada. O principal objetivo deste estudo foi a identificação molecular de variantes genéticas nos genes LDLR, APOB e APOE que provoquem dislipidémia. Os doentes referenciados para o Estudo Português de Hipercolesterolemia Familiar em 2015/2016 foram o alvo deste projeto. A realização de estudos funcionais ao nível do RNA para variantes que afetam o splicing foi também objetivo deste estudo. Neste projeto, foram estudados 60 casos índex incluídos no Estudo Português de Hipercolesterolemia Familiar. O estudo molecular foi dividido em várias fases: 1. O DNA genómico é isolado a partir dos linfócitos do sangue periférico; 2. Os 18 exões, regiões adjacentes e o promotor do gene LDLR, parte dos exões 26 e 29 do gene APOB e o exão 4 do gene APOE foram amplificados por PCR e sequenciados pelo método de sequenciação direta de Sanger. As sequências foram analisadas em computador e comparadas com as sequências de referência de forma a detetar variantes que possam ser a causa desta doença, confirmando o diagnóstico clínico; 3. Estudo de grandes rearranjos por Multiplex Ligation-dependent Probe Amplification (MLPA). Foram realizadas predições in silico para todas as alterações encontradas para prever o seu impacto ao nível da proteína. Para as alterações em regiões codificantes foram utilizadas as ferramentas PolyPhen-2, SIFT, PROVEAN e Mutationtaster. As ferramentas HSF, NNSSP e FSPLICE foram usadas para prever o efeito no splicing causado pelas alterações em regiões intrónicas. Quando nenhuma mutação é encontrada nestes três genes e o doente apresenta um fenótipo agressivo, procede-se à pesquisa no gene PCSK9 e em todo o gene APOB, representando a quarta fase do estudo molecular. Quando são encontradas variantes de patogenicidade desconhecida, são realizados estudos funcionais in vitro (fase 5). Embora o estudo completo dos genes PCSK9 e APOB não tenha sido realizado durante este trabalho, foram feitos estudos funcionais ao nível do RNA. No total, foram identificadas 18 variantes diferentes em 24 destes doentes: 16 no gene LDLR, 1 no gene APOB e 1 no gene APOE. Apenas 11 destas apresentam estudo funcional. Sempre que existia amostra disponível, foi feito também o estudo genético dos familiares, o que permitiu a identificação e caracterização genética adicional de 28 indivíduos, num total de 43 doentes com uma alteração possivelmente patogénica. Entre estas mutações encontram-se 3 nonsense, 12 missense e 3 que possivelmente afetam o splicing. Uma destas mutações foi descrita, pela primeira vez, em Portugal neste projeto. A análise de grandes rearranjos não revelou alterações deste tipo no grupo em estudo. A confirmação dos efeitos causados ao nível do splicing foi feita para duas das três alterações de splicing encontradas no gene LDLR durante este projeto. Para tal, recorreu-se ao isolamento das células mononucleares do sangue periférico dos doentes e à extração do RNA utilizando o RNeasy® Mini Kit (Qiagen). Após retrotranscrição para cDNA e amplificação da zona a estudar utilizando primers específicos, as bandas em gel de agarose foram analisadas e os fragmentos foram sequenciados. As duas alterações em causa levam ao skipping de exões e ao aparecimento de codões stop prematuros: no caso da alteração c.1060+1G>A, a inativação do donor site no intrão 7 resulta no skipping do exão 7; a alteração no último nucleótido do exão 16 (c.2389G>A) leva ao aparecimento de um novo acceptor site e, consequentemente, ao skipping do exão 16. A FH é caracterizada por níveis elevados de colesterol plasmático desde a nascença. Por isso, é de extrema importância que o diagnóstico seja feito o mais cedo possível, principalmente em idade pediátrica para que estas crianças recebam acompanhamento médico personalizado durante toda a vida, prevenindo o aparecimento de DCV prematura, permitindo, assim, uma melhor e maior esperança de vida. No entanto, é necessária uma maior divulgação da doença, principalmente junto do corpo clínico dos hospitais e centros de saúde assim como junto do público em geral. Só após a identificação clínica se pode realizar o estudo genético para comprovar a doença e o doente pode então receber acompanhamento e tratamento personalizado.
Cardiovascular disease (CVD) remains the most common cause of death globally. Dyslipidaemia is one of the most important risk factors that leads to CVD. It can be due to a monogenic condition or to polygenic/environmental causes as diabetes, obesity, tobacco use, excess of alcohol or reduced physical activity. The identification of the individuals at risk and the distinction of these two types of dyslipidaemia is important for a correct cardiovascular risk assessment, counselling, and treatment reducing, this way, cardiovascular mortality. Familial hypercholesterolaemia (FH) is an autosomal dominant disorder of cholesterol metabolism. Most commonly, FH results from inherited defects in the Low-Density Lipoprotein Receptor Gene (LDLR) leading to increased levels of circulating LDL cholesterol and lipid accumulation in arteries and tendons. Mutations in other genes as the apolipoprotein B gene (APOB) and proprotein convertase subtilisin/kexin type 9 gene (PCSK9), are also responsible for FH. The distribution pattern of apolipoprotein E gene (APOE) polymorphisms affects the affinity to lipoprotein receptors and, consequently, the clearance of dietary fat from the blood, also causing dyslipidaemia. The homozygous form of FH is rare and more severe, but the heterozygous form is common, with a frequency of 1/500 in most of European countries, although underdiagnosed in several populations, including the portuguese. FH is characterized by increased levels of plasmatic cholesterol since birth, which results in cholesterol deposits in extravascular tissues that can be identified in young patients (below 45 years old): xanthelasma, corneal arcus deposits and tendon xanthomas. This accumulation can cause premature arteriosclerosis and coronary heart disease (CHD). The presence of tendon xanthomas allows the differentiation of FH from other causes of hypercholesterolaemia as polygenic hypercholesterolaemia. More than 1700 different alterations in LDLR gene have been described worldwide. However, the functional studies for the great majority of these variants, have not been performed. For patients carrying these variants, a definitive molecular diagnosis for FH is not possible, representing a serious problem for FH diagnosis. In 1999, the Portuguese FH study was established at the National Institute of Health to identify the genetic cause of hypercholesterolaemia in individuals with a clinical diagnosis of FH. Index patients are included in this study using an adaptation of the Simon Broome (SB) criteria. Nonetheless, FH remains underdiagnosed and undertreated in the portuguese population. The main aim of this project was to perform the molecular identification of genetic variants in LDLR, APOB and APOE genes, causing dyslipidaemia in patients referred to the Portuguese FH Study in 2015/2016 with a clinical diagnosis of FH, in order to improve the identification of individuals at risk. Functional studies in RNA for putative splicing variants were also performed. The molecular diagnosis was performed for 60 index cases. Genomic DNA was isolated from peripheral blood lymphocytes using the salting out method. The 18 exons and promotor region of LDLR, part of exons 26 and 29 of APOB and exon 4 of APOE were amplified by PCR and sequenced by direct Sanger sequencing. A total of 18 variants were identified in 24 of these patients. The cascade screening in relatives of these 24 index patients allowed the identification and genetic characterization of additional 19 FH patients in Portugal. All alterations found have been previously reported, although only 11 had been functionally assessed. The search for large rearrangements was performed by Multiplex Ligation-dependent Probe Amplification (MLPA). In silico analysis was performed for all the variants found. In order to access the effect of splicing mutations, RNA was isolated from patients’ blood with RNeasy® Mini Kit (Qiagen), after isolation of peripheral blood mononuclear cells, and then transcribed to cDNA. Regions of interest were amplified with specific primers designed to evaluate the effect on cDNA of two of the tree putative splicing variants found in LDLR gene. Specific detection of each transcript was accessed by an agarose gel and the fragments were sequenced by Sanger sequencing. Both alterations lead to skipping of an entire exon and create premature stop codons: c.1060+1G>A causes an inactivation of the donor site in intron 7 resulting in skipping of exon 7; the alteration in the last nucleotide of exon 16 (c.2389G>A) creates a new acceptor site causing the skipping of exon 16. The early genetic identification of a mutation, confirming the clinical diagnosis of FH, is very important, especially for young patients, since they can receive appropriate dietary and lifestyle advice and adequate therapeutic measures providing them longer and better lives.

The aim of this diploma thesis was to set immunohistochemical detection of nuclear transcription factor kappaB (NF-κB). We studied its expression in aortic sinus in 8 and 16 weeks old apoE/LDL receptor deficient mice. Female apoE/LDL receptor mice were divided into two groups. The first group (n=8) was represented by eight weeks old mice. In the 16 weeks group (n=8) mice were fed with cholesterol enriched diet (0.15% of cholesterol) for the period of eight weeks. Indirect fluorescence immunohistochemistry with detection of antibody reaction with CY3 red fluorochrome was used for the detection of active form of NF-κB. In 8 weeks old mice the NF-κB expression was detected in endothelial cells and in some smooth muscle cells in vessel media. In 16 weeks old mice the NF-κB expression was detected inside atherosclerotic plaques and in vessel media under these plaques predominantly by macrophages and smooth muscle cells. In conclusion, the results of immunohistochemical analysis showed induction of inflammatory reaction by various cells during atherogenesis in blood vessels of apoE/LDL receptor deficient mice which will be used in prospective studies.

Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biological and Medical Sciences Title of Diploma Thesis: Western blot analysis of selected inflammatory markers in aorta of apoE/LDLR deficient mice Author: Jana Krejcarová Supervisor: PharmDr. Jana Rathouská, Ph.D. Background: This thesis was focused on the detection and subsequent evaluation of the expression of adhesion molecules ICAM-1, VCAM-1 and COX-2 and P-selectin in mouse aortas. Control and monitored group of mice differed in the genetic material, where monitored group of mice had unfunctional genes for apolipoprotein E and LDL receptor (apoE−/− /LDLR−/− ). Methods: For the study, two months old male mice of the C57BL/6J strain were used. Males were divided into two groups - control and monitored with unfunctional receptor for low- density lipoprotein and for apolipoprotein E. Both groups were fed by a standard diet for rodents. For detection and subsequent quantification of the expression of the markers VCAM-1, ICAM-1, COX-2 and P-selectin, Western blot analysis was used. Levels of soluble ICAM-1 and P-selectin in plasma were assessed by Luminex®. Results: Western blot analysis showed no significant difference in the expression of VCAM-1, ICAM-1, COX-2 and P-selectin between both groups of mice. Using the...