Thèses sur le sujet « Liver fibrosis progression »

Hepatic fibrosis is characterized by intense tissue remodeling. In this study, we assessed whether CO3-610, a new identified neoepitope, could be used as a surrogate biomarker of liver fibrosis and portal hypertension in CCl4-induced experimental fibrosis. Serum CO3-610 was measured by ELISA. Liver fibrosis was quantified by Sirius red staining. Serum hyaluronic acid (HA) was measured with a binding-protein assay. Gene expression of collagens I and III, MMP2 and MMP9, and tissue inhibitors of matrix metalloproteinase 1 and 2 was quantified by PCR. Hemodynamic measurements were taken in a subgroup of animals. A close direct relationship was found between serum CO3-610 and hepatic collagen content (r= 0.78; P<0.001), superior to that found for serum HA (r= 0.49; P<0.05). CO3-610 levels in rats with severe fibrosis (43.5±3.3 ng/mL, P<0.001) and cirrhosis (60.6±4.3 ng/mL, P<0.001) were significantly higher than those in control animals (26.6±1.3 ng/mL). Importantly, a highly significant relationship was found between serum CO3-610 and portal hypertension (r= 0.84; P<0.001). Liver MMP9 expression increased significantly in fibrotic animals but decreased to control levels in cirrhotic ones. Circulating CO3-610 behaves as a reliable indicator of hepatic remodeling and portal hypertension in experimental fibrosis. Therefore, this peptide could ultimately be a useful marker for the management of liver disease in patients. Endocannabinoids behave as antifibrogenic agents by interacting with cannabinoid CB2 receptors, whereas the apelin (AP) system acts as a proangiogenic and profibrogenic mediator in the liver. This study assessed the effect of long-term stimulation of CB2 receptors or AP receptor (APJ) blockade on fibrosis progression in rats under a non-discontinued fibrosis induction program. The study was performed in control and CCl4-treated rats for 13 weeks. Fibrosis-induced rats received a CB2 receptor agonist (AM1241) (1 mg/kg), an APJ antagonist (F13A) (75 μg/kg), or vehicle daily during the last 5 weeks of the CCl4 inhalation program. Mean arterial pressure (MAP), portal pressure (PP), hepatic collagen content, angiogenesis, cell infiltrate, and mRNA expression of a panel of fibrosis-related genes were measured in all animals. Fibrosis-induced rats showed increased hepatic collagen content, reduced MAP, PP, and increased expression of the assessed messengers in comparison with control rats. However, fibrotic rats treated with either AM1241 or F13A had reduced hepatic collagen content, improved MAP and PP, ameliorated cell viability, and reduced angiogenesis and cell infiltrate compared with untreated fibrotic rats. These results were associated with attenuated induction of PDGFRβ, α-SMA, MMPs, and TIMPs. CB2 receptor stimulation or APJ blockade prevents fibrosis progression in CCl4-treated rats. The mechanisms underlying these phenomena are coincident despite the marked dissimilarities between the CB2 and APJ signaling pathways, thus opening new avenues for preventing fibrosis progression in liver diseases. PDGF is the most potent stimulus for proliferation and migration of stellate cells. PDGF receptor β expression is an important phenotypic change in myofibroblastic cells that mediates proliferation and chemotaxis. Here we analyzed the relationship between PDGFRβ expression, hemodynamic deterioration, and fibrosis. Thereafter, we investigated the effects produced by an adenovirus encoding a dominant-negative soluble PDGFRβ (sPDGFRβ) on hemodynamic parameters, PDGFRβ signaling pathway, and fibrosis. Hemodynamics, PDGFRβ mRNA expression, and hepatic collagen were assessed in controls and fibrosic/cirrhotic rats. Next, 30 fibrotic rats were randomized into three groups receiving iv saline and an adenovirus encoding for sPDGFRβ or β-galactosidase. After 7days, hemodynamics, serum sPDGFRβ, and hepatic collagen were measured. CCl4-treated animals for 18weeks showed a significantly higher increase in PDGFRβ mRNA compared to those treated for 13weeks and control rats. In CCl4-treated rats, the fibrous tissue area ranged from moderate to severe fibrosis. A direct relationship between the degree of fibrosis, hemodynamic changes, and PDGFRβ expression was observed. Fibrotic rats transduced with the adenovirus encoding sPDGFRβ showed increased MAP, decreased PP, lower activation of the PDGFRβ signaling pathway, and reduced hepatic collagen than fibrotic rats receiving β-gal or saline. PDGFRβ activation closely correlates with hemodynamic disorders and increased fibrosis in CCl4-treated rats. Adenoviral dominant negative soluble PDGFRβ improved fibrosis. As a result, the hemodynamic abnormalities were ameliorated. Cirrhotic patients have altered host-defense response mechanisms. Here we assessed whether impaired expression of CB2 receptor in monocytic cells of cirrhotic patients could be involved in the pathogenesis of this phenomenon. CB2 mRNA and protein expression was assessed in a differentiated human monocytic cell line (U937) stimulated with endotoxin (LPS). A PCR array of 86 different genes was assessed in U937 cells treated with LPS. A migration assay towards endocannabinoids or the CB2 antagonist, SR144528, was performed in U937 cells exposed to LPS. Finally, CB1 and CB2 mRNA expression were measured in monocytes and macrophages of cirrhotic patients with or without spontaneous bacterial peritonitis. LPS reduced CB2 expression in human monocytes. Endocannabinoids increased the migratory activity of U937 cells, which was reverted when the experiments were performed in the presence of LPS. Transcriptional profiling showed marked upregulation of 9 genes related to proinflammatory signaling. However, only two genes encoding for CB1 and CB2 were reduced in LPS-treated cells. Circulating monocytes of cirrhotic patients showed a significantly diminished mRNA expression of CB1 and CB2. Markedly low CB1 and CB2 mRNA levels were found in peritoneal macrophages of cirrhotic patients with ascites, being almost suppressed when analyzed in patients with peritonitis. LPS reduces CB2 expression in human monocytes resulting in depressed chemotactic activity and therefore impaired host defense response of these cells.
La característica más destacable de la fibrosis es la desregulación de la ME. El equilibrio que existe entre la síntesis y la degradación de la ME en un hígado normal se pierde, y como consecuencia se favorece la síntesis y acumulación de fibras de colágeno, el cual provoca la distorsión de la arquitectura del parénquima y de la red vascular hepática. El CO3-610 es un producto de degradación del colágeno III que ha mostrado estar correlacionado significativamente con el aumento de la cantidad de colágeno y progresión de la fibrosis. Los valores máximos de CO3-610 se han encontrado ratas cirróticas. El resultado más importante es que el CO3-610 ha mostrado tener una estrecha correlación con los valores de presión portal. Existe un gran interés en investigar y desarrollar terapias dirigidas a la prevención de la progresión de la fibrosis. Los endocannabinoides son moléculas lipídicas que participan en un amplio rango de procesos fisiológicos. Los efectos son mediados por dos tipos de receptores, el CB1 y el CB2. El sistema de la apelina es otro sistema endógeno que ha despertado mucho interés en los últimos años. La apelina es el único ligando conocido para el receptor APJ. El tratamiento con AM1241, un agonista selectivo de CB2 y F13A, un antagonista de APJ mejoró la función hepática, la hemodinámica sistémica y portal, y provocó una reducción significativa del grado de fibrosis hepática. Ambos tratamientos produjeron una disminución del infiltrado inflamatorio, angiogénesis y del grado de apoptosis en el parénquima hepático. El análisis de la expresión del mRNA de varios genes importantes implicados en el proceso fibrogénico, reveló que el tratamiento tanto con AM1241 como con F13A, producían una disminución de la expresión del PDGFRβ, del αSMA y de genes de remodelado tisular. La inhibición parcial de la vía de PDGF mediante la administración de un dominante negativo para la fracción soluble del receptor β de PDGF, ha demostrado que mejora la hemodinámica sistémica y la presión portal además de mejorar el grado de fibrosis. Por último, los pacientes cirróticos con ascitis tienen una mayor probabilidad de sufrir infecciones (peritonitis bacteriana espontánea, PBE). Se ha observado que estos pacientes tienen una menor expresión de CB2. In vitro se han realizado experimentos con células monocíticas (U937) y se ha observado que el LPS disminuye drásticamente la expresión de CB2 al igual que afecta a la capacidad de migración de estas células. En conjunto, se puede concluir que la evaluación de la fibrosis hepática es una herramienta muy importante para el diagnostico de la enfermedad hepática y que éste puede mejorarse a través del uso de biomarcadores no invasivos que correlacionen con la hemodinámica y el grado de fibrosis hepática. La prevención de la progresión de la fibrosis a través de fármacos o bien actuando sobre genes clave involucrados en la fibrogénesis son posibles dianas terapéuticas. Finalmente, es posible mejorar la calidad de vida de los pacientes cirróticos con ascitis con infección por PBE mediante terapias que involucren los receptores de cannabinoides CB2.

La maladie alcoolique du foie (MAF) et l’hépatite C chronique (HCC) sont les causes les plus fréquentes de cirrhose, carcinome hépatocellulaire (CHC) et transplantation hépatique dans les pays industrialisés. La fibrose hépatique est le stigmate lésionnel de la progression de la maladie vers la cirrhose comme dans toutes les hépatopathies chroniques. Certains facteurs de risque cliniques environnementaux ont été identifiés. Toutefois, ils n’expliquent pas l’extrême variabilité individuelle de la progression de la fibrose. L’influence ethnique à développer une maladie plus sévère ainsi que les études de concordance des jumeaux mono- et di-zygotiques sur la prévalence de la cirrhose alcoolique ont suggéré l’existence de facteurs génétiques associés. Les nombreuses études de gènes candidats réalisées n’ont identifié que très peu de variants associés de manière reproductible. Pour l’HCC par exemple, le score de risque de cirrhose ou « CRS » a montré sa capacité à prédire une fibrose avancée dans diverses cohortes caucasiennes. Récemment, une étude d’association pangénomique (GWAS) dans la stéatohépatopathie non-alcoolique (NAFLD) a mis en évidence un singleton (single nucleotide polymorphism [SNP]) particulier (rs738409 C>G) dans le gène PNPLA3. Ce dernier s’est révélé être, dans diverses études, le SNP ayant l’impact le plus robuste et le plus reproductible dans cette maladie. Par ailleurs, ce même variant a également été significativement associé à la cirrhose alcoolique chez les hispaniques.

Les travaux réalisés dans le cadre de cette thèse ont permis de montrer que :

1) Le CRS avait la capacité de prédire la progression de la fibrose chez des patients caucasiens ayant une HCC dans 2 cohortes européennes indépendantes.

2) Par ailleurs, dans la MAF, nous avons répliqué chez des patients caucasiens l’association entre le SNP rs738409 dans le gène PNPLA3 et la cirrhose. Nous avons également montré pour la première fois, que l’expression de PNPLA3 était significativement diminuée chez les patients avec une fibrose plus avancée. De plus, nous avons observé dans 2 cohortes européennes que rs738409 était également associé à la prévalence du CHC.

3) Enfin, nous avons également mis en évidence l’impact de ce même SNP sur la stéatose hépatique et la fibrose dans l’HCC sans toutefois qu’il influence la réponse à la thérapie antivirale dans 3 cohortes caucasiennes indépendantes.

Ainsi de manière remarquable, un même SNP (rs738409) apparait associé à des lésions hépatiques sévères dans les trois pathologies hépatiques chroniques les plus fréquentes (la MAF, l’HCC et la NAFLD). Ceci suggère des voies pathogéniques communes de la fibrogénèse hépatique. Par ailleurs, ces travaux soulignent indirectement que les GWAS ont la capacité d’ouvrir de nouvelles voies physiopathologiques et d’identifier de nouveaux variants, gènes ou région génétiques capables de constituer de nouveaux biomarqueurs et cibles thérapeutiques dans l’HCC et la MAF.
Doctorat en Sciences médicales
info:eu-repo/semantics/nonPublished

Obesity and insulin resistance are associated with a constellation of features including hypertension, dyslipidaemia, type 2 diabetes, and premature cardiovascular disease, collectively termed the metabolic syndrome. Non-alcoholic fatty liver disease (NAFLD) represents the hepatic component of this syndrome, incorporating a spectrum of liver disease with increasing morbidity and mortality, from simple steatosis, to non-alcoholic steatohepatitis (or NASH), fibrosis, cirrhosis and ultimately hepatocellular carcinoma. However, factors influencing this progression are incompletely understood. In this thesis I sought to investigate pathways which promote hepatic inflammation and fibrosis by studying two contrasting dietary models of NAFLD in mice in which the risk of hepatic inflammation, insulin resistance and fibrosis differ; namely the methionine and choline deficient diet (MCDD) which induces steatohepatitis, hepatic insulin resistance, and weight loss, and the choline deficient diet (CDD) which may be protected from insulin resistance, and leads to steatosis without inflammation or weight loss. I investigated the possible molecular mechanisms underlying these differences, and whether they influenced progression to hepatic fibrosis induced by carbon tetrachloride (CCl4).

Thesis (M.A.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
Liver biopsy has been considered the gold standard method to assess the progression of fibrosis in chronic hepatitis C viral infection. Despite its prevalent use, significant complications along with patient discomfort are often reported. A reliable, non-invasive method to assess rapid fibrosis progression in patients with HCV infection must be determined. This study involved 57 subjects that underwent liver transplantation due to end stage liver disease as a result of chronic HCV infection. Serum samples were collected from all subjects at time of biopsy. Measurement of YKL-40 was performed using ELISA assays. Serum samples collected for all subjects at time of biopsy had a total YKL-40 concentration range from 38-1442 ng/mL with a mean of 228.74 ng/mL and a standard deviation of 271.26 ng/mL. The median YKL-40 concentration was 128 ng/mL. Serum YKL-40 is a reliable marker of rapid fibrosis progression and can be used in combination with other markers to accurately predict rapid fibrosis progression in HCV infected patients post orthotopic liver transplantation.

Les maladies chroniques du foie (CLD) sont associées au développement de la fibrose et caractérisées par un dépôt excessif de matrice extracellulaire (MEC), conduisant à une cirrhose et au carcinome hépatocellulaire (CHC). Lors d'une lésion hépatique, les hépatocytes endommagés déclenchent une réponse inflammatoire qui active les cellules étoilées hépatiques (CEH). Une fois activées, ces cellules se transdifférencient en myofibroblastes et produisent des composants de la MEC parmi lesquels les protéines de la famille des adamalysines (ADAM et ADAMTS). Quand le tissu est cicatrisé, la sénescence et d'autres mécanismes contribuent à la clairance ou à la réversion des CEHs. Récemment, nous avons identifié ADAMTS12 comme une adamalysine potentiellement impliquée dans la progression des CLDs. L’objectif de cette étude était d’explorer les fonctions cellulaires d'ADAMTS12 dans les CEH, et son rôle dans les CLDs. Chez les patients atteints de CHC, nous avons montré que l'expression d'ADAMTS12 est associée à l'agressivité et à la récidive des tumeurs. ADAMTS12 est exprimée par les CEH et par la lignée cellulaire LX-2 dérivée des CEH, mais pas par les hépatocytes. La fibrose induite par le CCl4 est exacerbée dans les souris ADAMTS12-/-. L’analyse transcriptomique de la lignée de CEH LX-2 montre une diminution de l'expression de PAI-I, un gène cible du TGF-β et un marqueur et médiateur de la sénescence lorsque l’expression d‘ADAMTS12 est réprimée par ARN-interférence (siADAMTS12). L'activation du TGF-β à partir de son précurseur LAP-TGF-β n’est pas affectée dans ce modèle mais on observe une diminution de la phosphorylation de smad2, suggérant que la répression du gène ADAMTS12 entraîne une inhibition de la voie SMAD de réponse au TGF-β. De plus, l’invalidation d'ADAMTS12 diminue la sénescence dans les LX-2. Par ailleurs, les données RNA-seq ont également montré une augmentation des gènes impliqués dans l'organisation du cil primaire dans les cellules siADAMTS12. L’immuno-détection d’une protéine du cil, ARL13b, a montré une augmentation du nombre de cils et une diminution de leur longueur dans les cellules siADAMTS12. De plus, l’absence d’ADAMTS12 dans LX-2 augmente le nombre de cellules en phase S. Nos résultats suggèrent qu'en absence d'ADAMTS12, les CEH échappent à la sénescence, ce qui, dans l'ensemble du contexte tissulaire, les rendrait compétentes pour la prolifération et la différenciation en myofibroblastes
Chronic Liver Diseases (CLDs) are associated with the development of fibrosis and characterized by excessive deposit of extracellular matrix (ECM), leading to cirrhosis and increasing risk of hepatocellular carcinoma (HCC). During liver injury, an inflammatory response activates the hepatic stellate cells (HSCs), whose function in normal liver is to store Vitamin A. Once activated these cells lose their vitamin A and transdifferentiate into myofibroblasts which produce ECM components among them proteins of the adamalysin (ADAM and ADAMTS) family. This family of metalloproteinases is implicated in several functions in the normal and pathological liver, and several members contribute to ECM remodeling in liver pathologies. Once the injury subsides, senescence and other mechanisms contribute to HSC clearance or reversion. Recently, we identified ADAMTS12 as an adamalysin potentially involved in CLD progression. The purpose of this study was to decipher the cellular functions of ADAMTS12 in HSCs and its role in CLDs. We found that in HCC patients, the expression of ADAMTS12 is associated with aggressiveness and recurrence. ADAMTS12 was expressed by activated HSCs as well as the HSC-derived LX-2 cell line, but not by the hepatocytes. CCl4-induced fibrosis was exacerbated in ADAMTS12 -/- mice. Transcriptomic analysis of the HSC-derived LX-2 cell line showed a down-regulation of the expression of PAI-1, a gene target of TGF-β and a marker and mediator of senescence upon ADAMTS12 silencing (siADAMTS12). TGF- β activation from its precursor was not affected in this model, although the phosphorylation of smad2 was decreased, suggesting that ADAMTS12 silencing leads to an inhibition of the SMAD-dependent TGF-β signaling pathway. In addition, silencing of ADAMTS12 decreased senescence in LX-2 cell line. Furthermore, RNA-seq data showed an up-regulation in genes implicated in the organization of primary cilium upon ADAMTS12 silencing. Immunodetection of the protein ARL13b, a primary cilium component, showed an increase in the number of cilia and a decrease in their length in siADAMTS12 cells. Additionally, ADAMTS12 silencing in LX-2 increased the G1 to S transition. Our results suggest that in the absence of ADAMTS12, HSCs escape senescence, which render them competent for myofibroblast differentiation and proliferation

Objective: Despite the evidence that antiretroviral treatment (ART) interruption increases the risk of various negative outcomes, it is still likely that HIV/hepatitis C (HCV) co-infected patients will discontinue ART for several reasons. The impact of interruption on liver fibrosis progression in co-infected adults was examined, using the aspartate aminotransferase-to-platelet ratio index (APRI) as a surrogate marker of liver fibrosis. Method: Time-dependent Cox regression, as well as inverse probability-of-treatment weighting (IPTW) in a marginal structural model, were used to evaluate the association of baseline and time-varying covariates with developing significant fibrosis. Results: After accounting for potential confounders, such as HIV viral load and CD4+ T cell count, the hazard ratio for ART interruption was 2.52 (1.20-5.28). Use of IPTW resulted in a similar estimate of effect, suggesting that mediation by time-varying confounders was negligible. Conclusions: ART interruption was independently associated with an increased risk of liver fibrosis progression in HIV/HCV co-infected patients.
Objectif: Certains patients coinfectés par le VIH et l'hépatite C interrompent leur traitement antirétroviral (TRT) pour des raisons variées, bien que cela augmente les risques de plusieurs effets indésirables. L'impact de l'interruption du traitement sur la progression de fibrose du foie chez des adultes coinfectés a donc été évalué grâce à l'utilisation du score APRI comme marqueur de fibrose du foie. Méthode: Un modèle Cox ainsi qu'un modèle marginal avec pondération par l'inverse de la probabilité de traitement ont été utilisés. Résultats: Après ajustement, le rapport de risque pour l'interruption du TRT était de 2.52 (1.20-5.28). Un effet similaire a été mesuré lorsque la pondération par l'inverse de la probabilité de traitement a été utilisée, ce qui suggère que l'effet des variables variant avec le temps était négligeable. Conclusions: L'interruption du TRT est indépendamment associée avec un risque accru de la progression de fibrose du foie chez les patients coinfectés avec le VIH et l'hépatite C.

Chronic Hepatitis C Virus (HCV) infection is associated with severe complications such as liver cirrhosis and hepatocellular carcinoma (HCC). For HCV infection, there is a crucial need for novel, preferably non‐invasive tests that could be used to improve the diagnosis and the management programs for patients at high risk of developing severe liver complications, such as cirrhosis and HCC. Classical biochemical markers to follow disease progression show limited potential mainly for invasiveness or little specificity and sensitivity, especially for HCC. The goal of this work was to discover useful biomarkers of disease progression in the setting of chronic HCV infection. In the first part, a Genome Wide Association Study was carried out to study the genetic variability influencing the natural history of HCV infection. A cohort of patients was genotyped and disease stage was evaluated through a liver biopsy before any antiviral treatment. Although no hits reached a genome-wide significance level, candidate regions showing suggestive association were identified. In particular, the gene region containing the GADD45G gene resulted of particular interest, given its role in cell biology. Conversely, the analysis of covariates revealed that they had a profound impact on the progression of the liver disease. Indeed, the age at infection had a marked effect on fibrosis progression (p < 2E‐16), suggesting that this is the major explanatory variable in our cohort. Male gender (p < 0.05) and HCV genotype 3 (p < 0.01) were also associated to faster fibrosis progression. The second part of this work focused on the use of circulating microRNA as blood-based biomarker of disease status. We investigated whether specific serum miRNA signatures may be detected in the serum of patients with chronic HCV infection at different stages of liver disease. Individual sera from healthy controls, patients with chronic hepatitis, liver cirrhosis or HCC were tested by high‐throughput qPCR to profile the expression of the whole miRNome. A solid normalization strategy was applied to reduce variability, and 22 miRNAs were considered differentially represented among the four classes (p<0.05 after multiple testing correction) The levels of miR‐122 and miR‐885‐5p specifically and consistently increased in patients with HCV infection compared to healthy controls or patients with Cronh’s disease (p<0.001). miR‐122 concentration changed significantly among groups with different alanine aminotransferase (ALT) activity (p<0.001), showing a positive trend. In summary, serum levels of miR‐122 and miR‐885‐5p were significantly elevated in patients with HCV‐associated liver pathologies. Our data show the potential use of serum miRNA as novel biomarker in the setting of chronic HCV infection.

En France, la consommation excessive d’alcool est la première cause de cirrhose et de carcinome hépatocellulaire (CHC), devant les hépatites virales et le syndrome métabolique. En 2016, on recense près de 10 500 décès par cirrhose ou CHC, et ce malgré une diminution significative de la consommation per capita d’alcool depuis 1960 (26L en 1960, 11,7L en 2017).Les personnes consommant de l’alcool ont un risque de développer une maladie du foie liée à l’alcool (MFLA). Elle évolue du stade initial de stéatose vers des stades plus avancés de fibrose et de cirrhose, pouvant se compliquer d’une décompensation ou d’un CHC. Avant l’apparition des complications, la MFLA est une pathologie asymptomatique et nombre de patients sont diagnostiqués tardivement, ce qui a des conséquences sur leur pronostic vital.Mettre en place des actions précoces auprès des consommateurs excessifs d’alcool pourrait permettre de réduire la morbi-mortalité hépatique par l’évitement ou le diagnostic plus précoce des complications. L’évaluation du bénéfice éventuel de telles actions de santé publique nécessite d’une part de connaitre les différentes étapes conduisant au développement des complications et d’autre part l’impact des facteurs de risque sur la progression ; ce afin de pouvoir déterminer les populations à cibler. Parmi les facteurs de risque identifiés, le syndrome métabolique joue un rôle important. Ainsi pour comprendre les mécanismes d’évolution de la MFLA, il est nécessaire d’étudier en parallèle ceux conduisant à la stéatopathie métabolique.L’histoire naturelle de la MFLA est encore mal décrite, notamment pour les stades précédant la cirrhose. La modélisation mathématique offre un cadre conceptuel qui permet de remédier aux problèmes éthiques que poserait une étude de terrain sur l’évolution de la MFLA.Ce travail a pour objectif principal de reconstruire mathématiquement l’histoire naturelle de la MFLA et de prédire la morbi-mortalité associée. Les objectifs secondaires sont d’estimer l’incidence de cette pathologie et d’identifier la population à risque. Pour cela, nous avons développé un modèle de Markov qui simule la trajectoire de cohortes d’individus à partir du moment où ils débutent une consommation d’alcool à risque jusqu’à leur décès. Il intègre les principaux facteurs de risque décrits comme associés à la progression de la MFLA dans la littérature (sexe, âge, surpoids et obésité, quantité d’alcool, polymorphisme génétique). Les paramètres inconnus de progression sont estimés par une méthode de rétrocalcul.Trois étapes ont été nécessaires pour alimenter et calibrer ce modèle : 1) caractériser la mortalité par cirrhose décompensée et par CHC liée à la consommation d’alcool ou au syndrome métabolique à partir des données fournies par Programme de Médicalisation des Systèmes d’Information ; 2) mettre en place un modèle de Markov sur des données d’hospitalisation de consommateurs excessifs pour estimer la progression de la fibrose; 3) mettre en place un modèle de Markov sur des données d’enquêtes réalisées en population générale française pour estimer le processus d’entrée dans une consommation à risque d’alcool ou de l’apparition du surpoids et de l’obésité.En conclusion, ce travail est le premier à caractériser la progression de la MFLA en population générale française. Il s’appuie sur des données épidémiologiques robustes auxquelles un éclairage nouveau est apporté. Les outils développés pourraient servir à tester l’impact de politiques de santé publique qui pourraient être mises en oeuvre auprès des populations les plus susceptibles de développer des lésions hépatiques
In France, excessive alcohol consumption is the leading cause of cirrhosis and hepatocellular carcinoma (HCC), ahead of viral hepatitis and metabolic syndrome. In 2016, there were nearly 10,500 deaths by cirrhosis or HCC, despite a significant decrease in per capita alcohol consumption since 1960 (26L in 1960, 11.7L in 2017).Alcohol drinkers are at risk of developing alcohol-related liver disease (ALD). It progresses from the initial stage of steatosis to more advanced stages of fibrosis and cirrhosis, which may lead to complications: decompensation and HCC. ALD is an asymptomatic disease prior to the onset of complications, and many patients are diagnosed late with life-threatening consequences.Implementing early actions targeting excessive alcohol drinkers could help to reduce liver morbidity and mortality through the avoidance or earlier diagnosis of complications. The evaluation of the possible benefit of such public health actions requires, on the one hand, knowledge of the different stages leading to the development of complications and, on the other hand, knowledge of the impact of risk factors on progression, in order to be able to determine the populations to target. Among the risk factors identified, the metabolic syndrome plays an important role. Thus, in order to understand the mechanisms of evolution of ALD, it is necessary to study in parallel those leading to non-alcoholic fatty liver disease (NAFLD).The natural history of ALD is still poorly described, especially for the stages preceding cirrhosis. Mathematical modeling provides a conceptual framework to overcome the ethical issues that would arise from a cohort study of the evolution of ALD.The main objective of this work is to mathematically reconstruct the natural history of ALD and to predict the associated morbidity and mortality. The secondary objectives are to estimate the incidence of this pathology and to identify the at-risk population. For this purpose, we developed a Markov model that simulates the trajectory of cohorts of individuals from the moment they start at-risk alcohol consumption until their death. It integrates the main risk factors described as associated with the progression of ALD in the literature (sex, age, overweight and obesity, amount of alcohol, genetic polymorphism). Unknown parameters of progression are estimated by a back-calculation method.Three steps were necessary to supply and calibrate this model : 1) characterize mortality by decompensated cirrhosis and HCC related to alcohol consumption or metabolic syndrome from data provided by the French National Hospital Discharge database; 2) set up a Markov model on hospitalization data of excessive consumers to estimate the progression of fibrosis; 3) implement a Markov model on survey data from the general French population to estimate the process of entry into at-risk alcohol consumption or the onset of overweight and obesity.In conclusion, this work is the first to characterize the progression of ALD in the general French population. It is based on robust epidemiological data to which new insights are provided. The developed tools could be used to test the impact of public health policies that could be implemented in populations most likely to develop liver damage

As células derivadas de fígado embrionário tanto de animais quanto de humanos tem sido cada vez mais estudas devido ao seu potencial antiinflamatório, imunomodulador e regenerativo, demonstrado as mesmas bipotencial de diferenciação em hepatócitos e colangiocitos. Na presente pesquisa utilizou-se células derivadas de fígados embrionários de ratos com 14,5 dias de gestação. As células apresentaram marcadores de células progenitoras hepáticas, bem como marcadores de células hepáticas e biliares diferenciadas confirmando, seu bipotencial. A terapia celular utilizando as células supracitadas, reduziu significativamente a progressão da fibrose hepática, diminuindo a inflamação e ainda estimulando a regeneração hepática de ratos submetidos à cirrose por ligadura do ducto biliar. As análises realizadas mediante avaliação quantitativa pela técnica de morfometria, demonstraram redução da deposição de fibras de colágeno, bem como menor proliferação de ductos biliares nos animais tratados. Os resultados foram ainda complementados por analise semiquantitativa, a qual avaliou a intensidade da necroinflamação dos tecidos hepáticos analisados, apontando menor escore de inflamação dos animais tratados. As células poderão ter efeito benéfico para o tratamento de doenças hepáticas crônicas, que estimulam a formação de fibrose. A cirrose é o estágio final comum à doenças hepáticas crônicas por causadas por fatores de diversas etiologias. Esta ocupa a decima quarta causa mundial de mortalidade em humanos, sendo que o único tratamento definitivo atualmente é transplante do órgão. Entretanto o número de transplantes está longe de suprir a demanda atual, visto que há um déficit de doadores do órgão. Terapias que possam oferecer uma alternativa de tratamento confiável, segura e acessível são bastante oportunas. Nossos resultados sugerem que as células utilizadas neste trabalho podem modular a fibrogênese, e consequentemente retardar o estabelecimento da cirrose em doenças hepáticas crônicas.
Studies on human and animal embryonic liver stem cells have been growing due to its anti-inflammatory, immunomodulatory and regenerative potential. These cells show also a bipotential do differentiate into hepatocytes and cholangiocytes. In the present study, it was used rodent embryonic liver with 14.5 of gestation. The cells presented hepatic progenitor, as well adult hepatic and biliary cells markers, confirming their bipotential. Previous studies with these cells in therapy decreased hepatic fibrosis progression in rat models submitted to cirrhosis by biliary duct ligation. Quantitative analysis was performed by morphometry showed decreased collagen fibers deposition and lower proliferation of biliary ducts in treated animals. Results were complemented with semiquantitative analysis with evaluation of necroinflammation of the analyzed hepatic tissues, in which a decreased inflammation score was observed. Cirrhosis is a common final stage for chronic hepatic diseases caused by different factors in several etiologies. It occupies the 14th world cause of mortality in human. However, the number of liver transplants is insufficient for current demand, caused by deficit in organs donors. Therapies that could offer an alternative for a reliable, safe and accessible treatment is opportune. Our results suggest that cells used in this study can modulate fibrogenesis and consequently delay the establishment of cirrhosis in chronic liver diseases.

INTRODUÇÃO: Pacientes com coinfecção HIV e hepatite C, em geral, apresentam rápida progressão da fibrose hepática. No entanto, a maior parte dos estudos, que avaliam essa questão, caracteriza a progressão da fibrose de forma indireta, utilizando para isso uma única biópsia hepática e tendo como base de cálculo o tempo estimado de infecção pelo vírus da hepatite C. OBJETIVO: Os objetivos do presente trabalho são: 1-Estimar a taxa de progressão da fibrose hepática de forma direta, através da análise de biópsias pareadas em pacientes coinfectados HIVhepatite C, não submetidos a tratamento prévio para hepatite C; 2- Avaliar a possível associação dessa progressão a determinadas variáveis clínicas. MÉTODOS: Trinta pacientes coinfectados com HIV e hepatite C, sem antecedente de tratamento prévio da hepatite C, submetidos a duas biópsias hepáticas pareadas foram avaliados. Calculou-se a taxa de progressão de fibrose direta e foram feitas determinações de progressão, estabilização e regressão da fibrose. Procedeu-se então à análise estatística, testando-se a associação entre progressão de fibrose e algumas variáveis clínicas e demográficas. RESULTADOS: A taxa de progressão média foi de 0,13 UF/ano, com 36,7% dos pacientes configurando-se como progressores. Em análise univariada, a progressão de fibrose hepática esteve associada a níveis de alanina aminotransferase (p<0,001) e aspartato aminotransferase (p<0,0340) acima de 3 vezes o limite superior da normalidade à época da primeira biópsia. Verificou-se também associação entre níveis de alanina aminotransferase (p=0,049) e aspartato aminotransferase (p=0,013) acima da normalidade e atividade necroinflamatória à primeira biópsia. CONCLUSÕES: Elevações de alanina aminotransferase e aspartato aminotransferase parecem estar associadas a uma maior atividade necroinflamatória em pacientes co-infectados pelo HIV e hepatite C e também a uma progressão mais acelerada da fibrose hepática nesse grupo de pacientes
INTRODUCTION: HIV and hepatitis C virus co-infected patients usually exhibit rapid liver fibrosis progression. However, most studies evaluating this issue indirectly characterize fibrosis progression via single liver biopsy, further using this as basis for calculating the estimated duration of hepatitis C infection. OBJECTIVE: Objectives of this study include: 1- Estimate the annual rate of direct liver fibrosis progression, using analyses of paired biopsy samples from HIVhepatitis C co-infected patients without prior treatment for hepatitis C; 2- Assess the possible association of fibrosis progression with certain clinical variables. METHODS: We evaluated 30 HIV-hepatitis C co-infected patients, with no history of prior treatment for hepatitis C, who underwent two paired liver biopsies. We calculated the annual rate of direct fibrosis progression and determined fibrosis progression, stabilization, and regression. We then performed statistical analysis, testing the association between fibrosis progression and several clinical and demographic variables. RESULTS: The average annual progression rate was 0.13 FU/year, with 36.7% of patients defined as progressors. In univariate analysis, liver fibrosis progression was associated with alanine aminotransferase (p<0.001) and aspartate aminotransferase (p<0.0340) levels over three times the upper limit of normal present at first biopsy. There was also an association between above-normal alanine aminotransferase (p=0.049) and aspartate aminotransferase (p=0.013) levels and necroinflammatory activity at first biopsy. CONCLUSION: Elevated alanine aminotransferase and aspartate aminotransferase levels appear to be associated with higher necroinflammatory activity and more accelerated liver fibrosis progression among HIV-hepatitis C co-infected patients

BACKGROUND AND AIMS: Congenital Hepatic Fibrosis (CHF) is caused by mutations in PKHD1, a gene encoding for fibrocystin, a protein of unknown function, expressed in cholangiocyte cilia and centromers. In CHF, biliary dysgenesis is accompanied by severe progressive portal fibrosis and portal hypertension. The mechanisms responsible for portal fibrosis in CHF are unclear. The αvβ6 integrin mediates local activation of TGFβ1 and is expressed by reactive cholangiocytes during cholestasis. To understand the mechanisms of fibrosis in CHF we studied the expression of αvβ6 integrin and its regulation in Pkhd1del4/del4 mice. METHODS: In Pkhd1del4/del4 mice we studied, at different ages (1-12 months): a) portal fibrosis (Sirius Red) and portal hypertension (spleen weight/body weight); b) αvβ6 mRNA and protein expression (RT-PCR, IHC); c) α-SMA and TGFβ1 mRNA expression (RT-PCR); d) portal inflammatory infiltrate (IHC for CD45 and FACS analysis of whole liver infiltrate); f) cytokines secretion from cultured monolayers of primary cholangiocytes (Luminex assay); g) cytokine effects on monocyte/macrophage proliferation (MTS assay) and migration (Boyden chamber); h) TGFβ1 and TNFα effects on β6 integrin mRNA expression by cultured cholangiocytes before and after inhibition of the TGFβ receptor type II (TGFβRII); i) TGFβ1 effects on collagen type I (COLL1) mRNA expression by cultured cholangiocytes. RESULTS: Pkhd1del4/del4 mice showed a progressive increase in αvβ6 integrin expression on biliary cyst epithelia. Expression of αvβ6 correlated with portal fibrosis (r=0.94, p<0.02) and with enrichment of a CD45+ve cell infiltrate in the portal space (r=0.97, p<0.01). Gene expression of TGFβ1 showed a similar age-dependent increase. FACS analysis showed that 50-75% of the CD45+ve cells were macrophages (CD45/CD11b/F4/80+ve). Cultured polarized Pkhd1del4/del4 cholangiocytes secreted from the basolateral side significantly increased amounts of CXCL1 and CXCL10 (p<0.05). Both cytokines were able to stimulate macrophage migration (p<0.05). Basal expression of β6 mRNA by cultured Pkhd1del4/del4 cholangiocytes (0.015±0.002 2^-dCt) was potently stimulated by the macrophage-derived cytokines TGFβ1 (0.017±0.002 2^-dCt, p<0.05) and TNFα (0.018±0.003 2^-dCt, p<0.05). Inhibition of TGFβRII completely blunted TGFβ1 (0.014±0.003 2^-dCt, p<0.05) but not TNFα effects (0.017±0.001 2^-dCt, p=ns) on β6 mRNA. COLL1 mRNA expression by cultured Pkhd1del4/del4 cholangiocytes (0.0009±0.0003 2^-dCt) was further and significantly increased after TGFβ1 stimulation (0.002±0.0005 2^-dCt, p<0.05). CONCLUSIONS: Pkhd1del4/del4 cholangiocytes possess increased basolateral secretory functions of chemokines (CXCL1, CXCL10) able to orchestrate macrophage homing to the peribiliary microenvironment. In turn, by releasing TGFβ1 and TNFα, macrophages up-regulate αvβ6 integrin in Pkhd1del4/del4 cholangiocytes. αvβ6 integrin activates latent TGFβ1, further increasing the fibrogenic properties of cholangiocytes.

A hepatite C é um processo inflamatório do tecido hepático que acomete milhões de pessoas em todo mundo. A evolução crônica da doença pode levar a transformação da fibrose hepática em cirrose e carcinoma hepatocelular em um grande número de casos. A avaliação dos graus de fibrose hepática é importante para o estudo da gravidade e progressão da doença, bem como decisão terapêutica e avaliação de sua eficácia. Os métodos não invasivos de avaliação da fibrose hepática têm sido uma opção aos possíveis riscos da biópsia hepática, ainda considerada o melhor método de avaliação de fibrose hepática. No presente trabalho, 107 pacientes portadores de hepatite C foram submetidos à biópsia hepática e Elastografia transitória hepática, 106 pacientes APRI e FIB4, ELF em 68 pacientes e ARFI em 51 pacientes. Usando a área abaixo da Curva ROC, AUROC, para obter a acurácia da fibrose hepática, encontramos na fibrose significativa ( >= F2): Elastografia transitória hepática: 0,83; FIB4: 0,76; ELF: 0,70; APRI: 0,69; ARFI: 0,67; na fibrose avançada ( >= F3): Elastografia transitória hepática: 0,85; ELF: 0,82; FIB4: 0,77; ARFI: 0,74; APRI: 0,71 e na cirrose ( >= F4) APRI: 1; FIB4: 1; Elastografia transitória hepática: 0,99; ARFI: 0,96; ELF: 0,94. Podemos dizer que em todos os graus de fibrose avaliados, a Elastografia transitória hepática foi o método que apresentou a melhor acurácia. Em se de tratando de cirrose (>=F4), todos os métodos não invasivos apresentam excelente acurácia. Utilizando o método Obuchowski, encontramos em cada grau de fibrose hepática classificado pelo escore METAVIR as acurácias: F1= Elastografia transitória hepática: 0,81; ARFI: 0,78; APRI: 0,72; FIB4: 0,67; ELF: 0,44; F2= Elastografia transitória hepática: 0,73; FIB4: 0,68; ELF: 0,63; APRI: 0,60; ARFI: 0,53; F3= ELF: 0,77; Elastografia transitória hepática: 0,70; FIB4: 0,67; ARFI: 0,64; APRI: 0,60 e F4: APRI e FIB4: 1; Elastografia transitória hepática: 0,98; ARFI: 0,96; ELF: 0,82. A Elastografia transitória hepática se mantém como um método eficiente para todos os graus de fibrose, sendo que nos extremos apresenta discreta superioridade em relação aos graus intermediários. A acurácia de todos os métodos é superior em F4
Hepatitis C is an inflammatory condition of the hepatic tissue that affects millions worldwide. The chronic stages of the disease turns from hepatic fibrosis into cirrhosis and hepatocellular carcinoma in many cases. The evaluation of fibrosis staging is important for prognosis, as well as understanding the progression of the disease, choice of treatment options and assessing their effectiveness. Non-invasive methods of fibrosis assessment have increasingly become alternatives to liver biopsy, which is still considered the best method of fibrosis assessment. In this study, 107 consecutive patients with hepatitis C virus were submitted to liver biopsy and transient elastography, 106 underwent APRI and FIB-4, 68 underwent ELF and 51 underwent ARFI. Using the area under ROC curve (AUROC) to obtain the degree of accuracy of each test, the following cutoffs were found for significant fibrosis (F >= 2): transient elastography: 0,83; FIB4: 0,76; ELF: 0,70; APRI: 0,69; ARFI: 0,67; For advanced fibrosis (F>=3): transient elastography: 0,85; ELF: 0,82; FIB4: 0,77; ARFI: 0,74; APRI: 0,71; For cirrhosis (F >= 4): APRI: 1; FIB4: 1; transient elastography: 0,99; ARFI: 0,96; ELF: 0,94. Of the methods assessed, transient elastography presented the greatest diagnostic accuracy across all levels of fibrosis. When assessing cirrhosis (F>= 4), all of these non-invasive methods showed excellent diagnostic accuracy. Using the Obuchowski method, the accuracy of each degree of fibrosis categorised by the METAVIR score was determined: F1= transient elastography: 0,81; ARFI: 0,78; APRI: 0,72; FIB4: 0,67; ELF: 0,44; F2=transient elastography: 0,73; FIB4: 0,68; ELF: 0,63; APRI: 0,60; ARFI: 0,53; F3= ELF: 0,77; transient elastography: 0,70; FIB4: 0,67; ARFI: 0,64; APRI: 0,60; F4: APRI and FIB4: 1; transient elastography: 0,98; ARFI: 0,96; ELF: 0,82. Transient elastography remained the most effective method for all degrees of fibrosis, although at the higher levels this superiority was less than at the intermediate levels. The accuracy of all methodologies was best at F >= 4

La stéatose hépatique non alcoolique, regroupant la stéatose isolée (NAFLD) et la stéatohépatite non-alcoolique (NASH), est un enjeu de santé publique mondial en raison d’une incidence croissante, en grande partie expliquée par l’augmentation de la prévalence du diabète et de l’obésité. La stéatose hépatique prédit la survenue des complications métaboliques associées à l’insulinorésistance, comme le diabète ou les événements cardiovasculaires. La connaissance de l’histoire naturelle de la NAFLD comporte encore de nombreuses incertitudes. Actuellement le modèle explicatif repose sur une dichotomie entre la stéatohépatite (NASH), qui peut progresser vers la cirrhose et la stéatose isolée ou avec inflammation minime (NAFL) qui jusqu'à présent était considérée comme une condition non évolutive ne progressant pas vers la cirrhose et n'augmentant pas la morbi-mortalité d'origine hépatique. Cette dichotomie conditionne en grande partie la prise en charge de ces patients, ceux avec NAFL étant souvent rassurés par le praticien quant à leur devenir et ne bénéficiant pas d'une surveillance hépatique spécifique. La ponction biopsie du foie est considérée comme un examen de référence, mais son usage en pratique clinique reste limité en raison d’effets indésirables, d’erreurs d'échantillonnage et de la variabilité d’interprétation inter-observateur. Les méthodes non invasives de lésions hépatiques sont devenues une vraie alternative à la biopsie du foie pour la prise en charge des patients ayant une maladie chronique du foie, au cours des dix dernières années
Non-alcoholic fatty liver disease (NAFLD) covers a spectrum ranging from isolated steatosis to non-alcoholic steatohepatitis (NASH) and is becoming one of the most frequent causes of chronic liver disease, mainly because of its close association with the worldwide epidemic of diabetes and obesity. Liver steatosis can predict the occurrence of metabolic complications associated with insulin resistance, such as diabetes and cardiovascular events. Our understanding of the natural history of NAFLD is still incomplete. Currently, the explicative model is based on a dichotomy between steatohepatitis, considered the progressive form of the disease, which can lead to cirrhosis and isolated steatosis with or without minimal inflammation, which is considered a non-progressive condition that does not impact overall survival or result in liver-related mortality and morbidity. This dichotomy largely determines the management of NAFLD patients: patients without steatohepatitis usually do not undergo specific monitoring for liver disease progression. Liver biopsy is considered the reference diagnostic method but its implementation in clinical practice remains limited due to procedure complexity, invasiveness, cost, potential complications, sampling error and inter-observer variability. Non-invasive methods of hepatic injury have become a real alternative to liver biopsy for the diagnosis of patients with chronic liver disease in the past decade. The aims of this thesis were: 1) to better understand the histological course of the disease, to better identify patients at risk of histological progression based on initial histological findings and to establish a correlation between histological changes and the course of metabolic co-morbidities often associated with NAFLD : 2) to establish factors associated with short-term variability of repeated measurements of elastometry in patients with chronic liver diseases in order to understand how this non invasive procedure can be used for patient monitoring 3) to determine the diagnostic value and limitations of several steatosis biomarkers using liver biopsy as a reference standard in a large cohort of patients with suspected NAFLD. Our study shows that a fraction of patients with isolated steatosis can unambiguously evolve towards well-defined steatohepatitis, and in some of them, bridging fibrosis. The presence of mild lobular inflammation or any amount of fibrosis substantially increases the risk of histological progression in the mid-term while those with steatosis alone are at lowest risk. Patients with disease progression experienced a deterioration of cardio-metabolic risk factors. Our data if validated by independent studies, allow for better stratification of patients at risk of disease progression. The results of this study favor a change in the practices of monitoring and risk assessment of patients with steatosis but without steatohepatitis

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Orientador: Maria Inês de Moura Campos Pardini
Coorientador: Rejane Maria Tommasini Grotto
Banca: Giovanni Faria Silva
Banca: Alexandre Neime Barbosa
Banca: Liliana Moura Massis
Banca: Paulo Inácio da Costa
Resumo: Não disponível
Abstract: Not available
Doutor

Atresia de vias biliares (AVB) é uma hepatopatia colestática específica da criança, de etiologia desconhecida, com evolução para fibrose hepática precoce. AVB é a principal causa de cirrose na infância e principal indicação de transplante hepático pediátrico (Tx). Compreender os fatores envolvidos na progressão da fibrose é fundamental para estabelecer tratamentos efetivos nas hepatopatias crônicas. Identificar padrões histopatológicos associados ao prognóstico da AVB permitiria melhor planejamento dos centros de transplante e adequado aconselhamento familiar. OBJETIVO: Estabelecer padrões de marcadores histopatológicos e de imunofluorescência para colágenos em biópsias hepáticas iniciais e finais de pacientes com AVB submetidos a tratamento cirúrgico. Correlacionar esses marcadores com o prognóstico da doença, definido com base no tempo de evolução até realização do Tx. MÉTODO: Avaliação histológica de alterações biliares e fibrose hepática e histomorfometria da fibrose marcada por picrossírius e da deposição dos colágenos tipos I, III, IV e V marcados por imunofluorescência indireta (IF), em biópsias hepáticas iniciais e finais de 36 pacientes com AVB submetidos à hepatoportoenterostomia de Kasai (KPE) e ao Tx nos últimos 20 anos em nossa instituição. RESULTADOS: A mediana das idades de realização da KPE foi de 12,5 semanas (6-20) e do Tx foi de 27 meses (6-120). Reação ductular e malformação de placa ductal foram mais intensas nas biópsias iniciais (p < 0,05), enquanto fibrose hepática e ductopenia apresentaram padrão progressivo (p < 0,001), sem correlações com a idade de realização da KPE nem com o tempo de evolução até Tx. A morfometria da fibrose hepática marcada pelo picrossírius nas biópsias iniciais apresentou correlação positiva com a idade da KPE (p = 0,01), mas não com a idade do Tx (p = 0,24). A deposição perissinusoidal dos colágenos dos tipos III e V foi mais intensa nas biópsias iniciais (p < 0,01), enquanto os colágenos dos tipos I e IV apresentaram padrão de deposição progressiva (p < 0,01). Pacientes com maior deposição perissinusoidal de colágeno tipo I nas biópsias iniciais apresentaram curva de tempo de evolução até Tx sugerindo pior prognóstico (p = 0,04). CONCLUSÃO: Marcadores histopatológicos de alterações biliares, fibrose hepática e deposição de colágenos apresentaram características evolutivas distintas nas fases inicial e final da AVB, sem correlação com o tempo de evolução até Tx. A morfometria da deposição perissinusoidal de colágeno tipo I em biopsias iniciais marcadas por IF pode ser correlacionada ao tempo de evolução até Tx em pacientes com AVB operada
Biliary atresia (BA) is a specific cholestatic liver disease of unknown etiology that affects children and progresses to early hepatic fibrosis. BA is the main indication of pediatric liver transplantation (LTx). Understanding the factors involved in the progress of fibrosis is essential to establish effective treatment to chronic liver disease. Histopathological markers in liver biopsies could be useful to predict progression to end stage disease and to make it possible to improve planning in transplantation centers and parental orientation. OBJECTIVE: To establish histopathological or immunohistochemical markers in initial or final liver biopsies of BA patients and correlate those markers with prognosis, as defined by progression time lapse until LTx. METHOD: Histological analysis of multiple parameters of biliary alterations and morphometrical assessment of liver fibrosis were performed, besides indirect immunofluorescence assays (IF) for type I, III, IV and V collagens in initial and final liver biopsies of 36 patients with BA submitted to Kasai hepatoportoenterostomy (KPE) and LTx in the last 20 years in a single center. RESULTS: The median of the ages at KPE was 12.5 weeks (6-20) and at LTx was 27 months (6-120). Ductular reaction and ductal plate malformation were more severe in the initial biopsies (p < 0.05), while ductopenia and liver fibrosis were more severe in final biopsies (p < 0.001), though without correlation with age at KPE nor with progression time lapse until LTx. Morphometrical assessment of liver fibrosis marked by picrosirius red in initial biopsies demonstrated positive correlation with age at KPE (p = 0.01) but not with age at LTx (p = 0.24). The perisinusoidal deposition of type III and V collagens was more extended in the initial biopsies (p < 0.01), while type I and IV collagens deposition indicated progression (p < 0.01). Patients with large amounts of perisinusoidal type I collagen in the initial biopsies had worse progression time curve until LTx (p = 0.04). CONCLUSION: Biliary alterations, liver fibrosis and collagens deposition demonstrated distinctive progression findings in the initial or final phases of the BA, without prognostic correlation. Morphometrical assessment of perisinusoidal deposition of type I collagen by IF in the initial biopsies can be correlated with progression time until LTx in patients with post-surgical BA

La cholestase intra-hépatique familiale progressive de type 1 (PFIC1) humaine est une maladie génétique rare, provoquée par des mutations du gène ATP8B1, due à un défaut de sécrétion des acides biliaires. Un syndrome moins sévère, et épisodique, appelé Cholestase Intra-hépatique Récurrente Bénigne (BRIC) a pu être associé à des mutations au sein du même gène. Les patients PFIC1 souffrent de nombreuses manifestations extra-hépatiques. Certaines de ces manifestations sont communes aux patients mucoviscidosiques. Le niveau d’expression de CFTR, gène responsable de la mucoviscidose, est diminué chez les patients PFIC1. Cette étude a porté sur l’analyse des interactions/régulations entre CFTR et ATP8B1. Une première approche a été de montrer l’expression de ces gènes dans différentes lignées cellulaires puis d’identifier la présence de leurs protéines par western blot et immunofluorescence. Une seconde approche a été d’effectuer une analyse in silico de la structure d’ATP8B1 par rapport à sa fonction. Nous avons aussi localisés les modifications connues sur un modèle 2D. Cette analyse a permis de mettre en évidence en plus des sites connus (ATPase et domaines transmembranaires), deux sites de maturations par clivage ainsi qu’un domaine riche en phosphorylation, des domaines PDZ et un domaine d’interaction avec des récepteurs nucléaires et des facteurs de transcription. A partir d’un polypeptide de 180 kDa, le clivage au niveau des sites identifiés produit un peptide de 145 kDa puis un de 90 kDa, révélés par western blot avec un anticorps dirigé contre la partie CTerminale de la protéine. Ce peptide de 90 kDa, après myristoylation, pourrait interagir avec des récepteurs nucléaires et des facteurs de transcriptions. Ces interactions nous ont permis de monter un modèle qui pourrait expliquer la diminution d’expression génique de différents gènes observés chez les malades PFIC1. Cette analyse a été poursuivie par une étude de l’interactome d’ATP8B1 qui a montré une interaction possible avec CFTR directement ou par l’intermédiaire d’une protéine de liaison, PDZK1. Une dernière étude a porté sur la fonctionnalité de CFTR dans deux lignées portant des mutations différentes d’ATP8B1. L’ensemble des résultats montre qu’ATP8B1 participerait à la régulation de l’expression du gène CFTR mais aussi à sa maturation fonctionnelle.
Human Progressive Familial Intrahepatic Cholestasis type 1 (PFIC1) is a rare genetic disease provoked by mutations inside the ATP8B1 gene resulting in a general loss of bile acids secretion. An episodic and less severe syndrome called Benign Recurrent Intrahepatic Cholestasis (BRIC) have also been associated with mutations in this gene. PFIC1 patients are suffering from many extra-hepatic manifestations. Some of these manifestations are common to Cystic Fibrosis (CF) patients, carrying mutations in CFTR gene. Moreover, expression of CFTR is decreased for some PFIC1 patients. This study was carried out to define the role of ATP8B1 in the modulation of CFTR gene expression and protein function. A first approach was to identify both gene expression and protein synthesis among various cell lines. Then, we developed a second approach based on in silico analysis of structure and function of ATP8B1 to construct a 2D model of the protein. This approach was correlated with the localization of known mutations of ATP8B1. This analysis showed two possible protein maturation sites, a rich phosphorylation domain and a nuclear receptor interacting domain. The cleavage of the 180 kDa peptide generates a 145kDa (ATPase) and a second cleavage produces a 90 kDa, all identified with a specific antibody directed toward the C-Terminal region of the protein. The 90 kDa peptide should be readdressed to the nucleus after myristoylation to interact with nuclear receptors and transcription factors. This analysis was completed by an interactomic approach which has shown a possible interaction between CFTR and ATP8B1 proteins either directly or mediated by a linker, PDZK1. The last part of this work was dedicated to assess the role of ATP8B1 on the activity of CFTR using two cell lines expressing two different mutated ATP8B1 genes. From all these results, we concluded that ATP8B1 is probably involved in the regulation of CFTR gene expression and CFTR maturation and function. We therefore propose a schematic representation of ATP8B1 synthesis and maturation associated with its putative biological functions in the cell.
Réalisé en cotutelle avec l'Université de Cergy-Pontoise