Dissertations / Theses on the topic 'Astrocytes Neuroinflammation'
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Brothers, Holly M. "Neuroinflammation, Glutamate Regulation and Memory." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1363603410.
Full textWu, Celina. "Dual agonist-antagonist functions of FTY720 influence neuroinflammation-relevant responses in human astrocytes." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110720.
Full textLes astrocytes sont les cellules gliales les plus abondantes du système nerveux central (SNC). Leur grande expression en filaments intermédiaires, la protéine acide fibrillaire gliale (GFAP), est une caractéristique permettant leur identification. Les astrocytes sont d'importants contributeurs aux événements biochimiques du SNC et jouent un rôle clé dans le processus de régulation des dommages et de la guérison du SNC. Sous des conditions d'inflammation chronique, tel la Sclérose en Plaques (SP), les astrocytes subissent des changements pathophysiologiques causant l'astrogliose (Liberto, Albrecht et al. 2004; Sidoryk-Wegrzynowicz, Wegrzynowicz et al. 2011). Ce mécanisme de cicatrisation est commun dans la SP et un nouvel agent thérapeutique, FTY720 (fingolimod, Gilenya™) démontre des effets protecteurs du SNC en prévenant l'évolution de l'astrogliose. (Choi, Gardell et al. 2011). FTY720 est un agent thérapeutique récemment approuvé pour traiter la SP. Il est administré oralement et a la capacité d'accéder au SNC. Une fois en place dans ce système, cet agent entre en contact direct avec le récepteur sphingosine-1-phosphate (S1PR) sur les astrocytes. Les réponses des astrocytes en réaction aux signaux générés par ce récepteur sont reliées à la pathologie de la SP. Cette thèse examine les signaux engendrés par FTY720 ainsi que ses fonctions sur les astrocytes humains primaires. Nous avons utilisé des astrocytes isolés à partir de SNC humains fœtaux pour examiner les réponses neuro-inflammatoires générées par l'administration quotidienne de FTY720. FTY720 agit initialement comme un agoniste en activant le récepteur S1P, mais il agit également comme un antagoniste en causant l'internalisation et la dégradation de ce récepteur. Nous avons examiné ces deux phénomènes de façon à savoir s'ils agissent en concert. Nous affirmons qu'un récepteur internalisé par FTY720 continue de générer des signaux pour une période de temps prolongée (heures). Une addition simple de FTY720 désensibilise l'astrocyte, pour une période de >24h, au signal de phosphorylation de ERK (pERK) qui est généré par le récepteur extracellulaire. Cette période réfractaire du signal de transduction de pERK fût maintenue dans les astrocytes traités quotidiennement avec FTY720, sinon le signal pERK reparaît 72 heures après le traitement initial. De plus, la désensibilisation du récepteur fût reliée à l'absence de réponse proliférative induite par le ligand naturel sphingosine-1-phosphate (S1P). Nous avons aussi démontré que le traitement quotidien des astrocytes avec FTY720 atténue la capacité de IL-1β à activer les voies moléculaires sensibles au calcium. Le traitement quotidien avec FTY720 n'inhibe pas les signaux de pERK lorsque les astrocytes sont stimulés à l'aide de sérum, ni la sécrétion de IL-6 ou de IP-10 lorsqu'ils sont stimulés avec IL-1β. Nos résultats suggèrent que l'exposition quotidienne à FTY720 agit comme un antagoniste aux stimuli extérieur (tel le ligand naturel S1P) ainsi qu'un agoniste lorsque le récepteur est internalisé (inhibe la mobilisation du calcium lorsqu'exposé à IL-1β).
Hoskins, Andrew. "The Role of IRF1 in the Brain and in Adaptive Responses of Astrocytes." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5757.
Full textClement, Tifenn. "Contribution of astrocytes in brain vulnerability after juvenile mild traumatic brain injury." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0141.
Full textAstrocytes are crucial for various physiological functions in the brain such as homeostasis, metabolism, neurovascular coupling or neurotransmission regulation. In injuries, astrocytes become reactive and have a crucial role in the neuroinflammatory response. This reactivity is heterogeneous and depends on many parameters such as the type and severity of insult, astrocyte proximity to insult, or state of brain maturity. However, the specific response of astrocytes to mild traumatic brain injury (TBI) in the developmental context has never been studied yet. Mild TBI is the leading cause of emergency department visits in the pediatric population. A significant proportion of mild TBI pediatric patients will suffer of long-lasting cognitive and emotional impairments but the underlying cellular and molecular mechanisms are still poorly understood. Astrocytes might take part to this vulnerability and be partly responsible for the long-term consequences.We investigated astrocyte response to juvenile mild TBI and hypothesized that: (1) astrocytes display a specific pattern of reactivity evolving over time and brain development; and that (2) astrocytes reactivity differs when the TBI is preceded by an early systemic inflammation inducing a priming of astrocytes, with a different neuroinflammatory and vascular response to juvenile mild TBI, impacting the brain vulnerability and long-term outcome.We have shown that:(1) Reactive astrocytes express a specific spatiotemporal reactivity pattern even at distance from the injury site, in terms of intermediate filaments expression and morphological evolution, and that structural alterations are observed in brain imaging on the long-term after juvenile mild TBI.(2) When the juvenile mild TBI is preceded by perinatal systemic inflammation, astrocytes express a different reactivity phenotype considered as a state of transition towards scar-forming astrocytes, with increased metabolism and extracellular matrix-related gene changes, associated to morphological alterations sustaining over time and delayed over-expression of VEGF, resulting in the absence of vascular alterations induced by TBI alone.This work brings new insights in the specificities of astrocyte reactivity and in the pathophysiology of vulnerability after juvenile mild TBI, opening possibilities for novel targets for therapeutics
Phillips, Emma Claire. "Investigating the contribution of astrocytes and neuroinflammation to pathological tau changes in Alzheimer's disease." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/investigating-the-contribution-of-astrocytes-and-neuroinflammation-to-pathological-tau-changes-in-alzheimers-disease(d96f6fa6-6870-4461-82b2-0a19d5507eab).html.
Full textDorey, Evan J. "Apolipoprotein E Isoforms Differentially Regulate Amyloid-β Stimulated Inflammation in Rat and Mouse Astrocytes." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23581.
Full textCeyzériat, Kelly. "Modulation de la réactivité astrocytaire par ciblage de la voie JAK2-STAT3 : conséquences dans des modèles murins de la maladie d’Alzheimer." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS556/document.
Full textAstrocytes are emerging as key players in brain physiology. In Alzheimer’s disease (AD), astrocytes become reactive. Astrocyte reactivity (AR) is essentially characterized by morphological changes. But how the normal supportive functions of astrocytes are changed by their reactive state is unclear. Moreover, signaling cascades leading to AR are not yet determined. In this study, we aim to: 1/ demonstrate the JAK2-STAT3 pathway (Janus Kinase 2 - Signal Transducer and Activator of Transcription 3) is responsible for AR in neurodegenerative diseases ; 2/ understand the contribution of reactive astrocytes to molecular, cellular and functional alterations in AD. We already reported that the JAK2- STAT3 pathway is a central cascade for AR (Ben Haim et al., 2015). Here, we demonstrate, with new molecular tools based on viral vectors, that this pathway is necessary and sufficient to AR. Our results also show that the modulation of AR in two AD mouse models (APP/PS1dE9 and 3xTg-AD mice) influence several pathological hallmarks, but in a context-dependent manner. Overall, this work has generated new original tools to study reactive astrocytes in situ and it underlines the importance and complexity of their functions in neurodegenerative diseases
Frakes, Ashley E. "The Role of Neuroinflammation in the Pathogenesis of Amyotrophic Lateral Sclerosis." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417649954.
Full textGuillot, Flora. "Caractérisation de l'infiltrat lymphocytaire et de la réactivité astrocytaire dans un modèle de neuroinflammation autoimmune." Nantes, 2014. https://archive.bu.univ-nantes.fr/pollux/show/show?id=eba4b03e-07fe-4198-a88d-16cbb5f7f5eb.
Full textMultiple sclerosis (MS) is an autoimmune, demyelinating and degenerative disease of the central nervous system (CNS), in which astrocyte reactivity is considered an important player. The CD4 T cell response is strongly associated with development of MS and its animal models such as experimental autoimmune encephalomyelitis (EAE). Recent data suggest that anti-myelin CD8 T cells may be also implicated as CD8 T cells are abundant in MS lesions. To better understand the contribution of pathogenic CD8 T cells, two animal models that have been described were evaluated. The first one consists of mice immunized with a specific CD8 T cell myelin epitope (MOG37-46). Mice develop mild EAE with CD4 T overwhelming CD8 T cells in CNS. Boosting the CD8 immune response increased slightly the CD8/CD4 ratio in the CNS. The second model is based on the adoptive transfer of anti-HemAgglutinin (HA) CD8 T cells in DKI transgenic mice, which express HA by oligodendrocytes. Only irradiation (2Gy) of DKI mice allowed CNS infiltration of CD8 T cells but without apparent clinical signs. These results are discussed in light of recent literature. In parallel, we characterized the astrocyte reactivity in a classical EAE to better define the implication of astrocytes in the pathology. For this, we used for the first time in this model laser-capture microdissection to isolate white matter astrocytes in spinal cord lesion. Selected transcript profiling analysis revealed astrocytic expression of pro-inflammatory mediators and enzymes involved in oestrogen metabolism. These results give new clues for targeting glial reactivity in neuroinflammatory disorders such as MS
Ben, Haim Lucile. "Modulation of the JAK2/STAT3 pathway in vivo : understanding reactive astrocyte functional features and contribution to neurodegenerative diseases." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066534/document.
Full textAstrocyte reactivity is a hallmark of pathological conditions in the CNS including neurodegenerative diseases (ND) such as Alzheimer’s (AD) and Huntington’s (HD) diseases. Reactive astrocytes (RA) are identified by morphological changes but their functional features and influence on neurons are poorly understood, especially in ND. Therefore, we aimed at 1) identifying the signaling cascades involved in astrocyte reactivity in ND, 2) evaluating RA contribution to disease phenotype in ND models and 3) deciphering RA functional features. The JAK2/STAT3 pathway is a known trigger of astrocyte reactivity in CNS injuries. Here, we show that this pathway is a common inducer of astrocyte reactivity in AD and HD models. We developed new viral vectors to target this cascade in astrocytes and manipulate astrocyte reactivity in vivo. We used these vectors to determine the contribution of RA to neuronal dysfunction in HD mouse models. We found that RA do not primarily influence disease phenotype in HD. Last, we targeted the JAK2/STAT3 pathway in WT mice to characterize RA functional features in vivo. We show RA undergo transcriptional changes of numerous genes involved in metabolism, protein degradation pathways and immune response. Moreover, we show that astrocyte reactivity alters synaptic plasticity in the mouse hippocampus. Our results identify the JAK2/STAT3 pathway as a central cascade for astrocyte reactivity. The viral vectors developed in this project represent powerful tools to decipher the roles of RA in various ND models and to characterize RA functional features in vivo. Better understanding RA functions may lead to the identification of new therapeutic targets for ND
Herber, Donna Lorraine. "Neuroinflammation in Alzheimers disease : characterization and modification of the response of transgenic mice to intrahippocampal lipopolysaccharide administration /." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0001075.
Full textLhuillier, Alice. "Identification de programmes d'activation macrophagique et microgliale dans les formes progressives de la sclérose en plaques." Phd thesis, Université Claude Bernard - Lyon I, 2014. http://tel.archives-ouvertes.fr/tel-01056829.
Full textO'Callaghan, Paul. "Heparan Sulfate in the Amyloidosis and Inflammation of Alzheimer’s Disease." Doctoral thesis, Uppsala universitet, Geriatrik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-159927.
Full textJukkola, Peter I. "The Role of Potassium Ion and Water Channels in an Animal Model ofMultiple Sclerosis." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397656579.
Full textVizuete, Adriana Fernanda Kuckartz. "Avaliação da neuroinflamação e da atividade astrocitária em modelo de epilepsia por Li-pilocarpina: S100B possível marcador e alvo farmacológico." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/165307.
Full textTemporal lobe epilepsy (TLE) is the most frequent type of epilepsy in humans and is more associated to refractory to anti-epileptic drugs (AED) in patients. The most AEDs are modulators of neuronal activity and act on ion channels, such as GABAA receptor. Studies have been demonstrating the role of glial cells and neuroinflammation in epileptogenesis. The modulation of this response may be a potential target for adjunctive drugs to anti-epileptic drugs. Astrocytes are glial cells that participated in the tripartite synapse and modulated neuronal activity. Astrocytes are able to promote homeostasis of ions and neurotransmitters, are responsible for energy metabolism and the production of neurotrophic factors, glutathione, glutamine, S100B and cytokines. In this work, we induced status epilepticus (SE) in young rats (PN28) through the lithiumpilocarpine model that mimics neuronal, biochemical and morphological alterations similar to ELT in humans. The animals were divided at times 1, 14 and 56 days after the induction of SE. These periods are characterized respectively as the acute, latent and chronic phase of epilepsy. Initially, we analyzed neurochemical and astrocytic changes over time. Initial and transient neuroinflammation was observed and promoted over time neuronal death, astrogliosis and astrocytic dysfunction. It has also been observed that the protein S100B, a calcium-binding protein, predominantly astrocytic, can be considered a marker of neuronal and astrocytic dysfunction promoted by this model of epilepsy. Next, we demonstrate that the modulation of S100B secretion by the antiinflammatory dexamethasone one day after SE induction reverses neuroinflammation, astrogliosis and astrocytic dysfunction in the acute and chronic time. Therefore, we analyzed that modulation of the GABAA receptor through GABAergics agonists and antagonists alters the secretion of S100B in acute hippocampal slices and in astrocyte culture. Therefore, it may be suggested that astroglial changes and time dependent neuroinflammation may be related to neuronal excitability and/or neuronal death in young rats in this epilepsy model; that S100B protein can be considered a marker of this epilepsy model and that the modulation of its secretion may be a possible pharmacological target in the treatment of epilepsy.
Bernardi, Caren Luciane. "Parâmetros comportamentais e bioquímicos gliais e inflamatórios em pacientes com lesão da medula espinhal submetidos à dança, e em ratos Wistar submetidos aos protocolos de exercício voluntário e forçado." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/143581.
Full textThe main aim of this Thesis was to evaluate the biochemical glial, inflammatory and behavioral parameters, in patient with spinal cord injury (SCI) submitted to a protocol of dance, and in rats submitted to voluntary and forced exercise. Four experiments were made. In the 1st, the rats were submitted to 4 weeks of moderate exercise on treadmill (20 min per day). In the 2nd, the animals were submitted to 4 weeks of voluntary exercise on wheel running (12 hours per day). In the 3rd experiment, the rats were exposed to treadmill during 2 weeks (20 min per day) and, after the last session, they received intraperitoneal injection of LPS. In this last experiment, the memory and learning were investigated. At the finish of the exercise period, or after the LPS injection, the biochemical analysis of the hippocampus was realized. The 4th experiment was realized with individuals with spinal cord injury that were submitted to 4 weeks of dance practice. Behavioral and serological analyses were performed. Data show that treadmill running increased glutamine synthetase (GS) activity and decreased hippocampal glial fibrillary acidic protein (GFAP) and nitric oxide (NO) , as well as increased corticosterone level, that can mediate the effects of the exercise on astrocytes. The voluntary exercise increased GS and BDNF. The LPS administration increased hippocampal TNF-α level in rats concomitantly with the increase in the S100B levels in cerebrospinal fluid. The individuals with spinal cord injury submitted to dance showed a significant improve in the scores of Functional Independency Measure, Barthel Index, Berg Scale and Ansiety and Depression Hospitalar Scale, and a increase in the serologic levels of BDNF. The dance had no effect on glial, metabolic and inflammatory parameters. These results suggest that different types of exercise exert different effects on hippocampal astrocytes, which may interfere with the appointment of one or the other depending on the objective to be achieved. The treadmill exercise can be a good strategy in the prevention of neuroinflammatory diseases, and dance can be an effective therapeutic intervention for rehabilitation of individuals with SCI as it helps to improve physical and psychological conditions in this population. Taken together, the present data highlight the importance of physical exercise for neural functions, and the relevance of studying astrocytes to understand the mechanisms involved in the effect of exercise on CNS.
Campos, Torres Antonio. "Contribution à l' étude des interactions neurones-glie dans la plasticité post-lésionnelle du système nerveux central adulte : la compensation vestibulaire." Paris 6, 2005. http://www.theses.fr/2005PA066484.
Full textVan, Gijsel-Bonnello Manuel. "Neuroinflammation et perturbations métaboliques au cours du vieillissement cérébral normal et pathologique (maladie d'Alzheimer) : exploration du potentiel protecteur de la pantéthine." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM5058/document.
Full textWe used two mouse models to explore the age-related cerebral alterations, under physiological and pathological conditions (Alzheimer’s disease), i.e. senescence accelerated SAM-P8 and transgenic 5xFAD mice.In the two models, mice showed signs of neuroinflammation with release of the major inflammatory cytokine IL-1β. Such events were undoubtedly of endogenous origin as they did not occur in the controls. It should be underlined that, since 5xFAD astrocytes were collected in newborns, their inflammatory status means that neuroinflammation is a very early step of Alzheimer’s disease pathological process, upstream of β-amyloid accumulation.Since in a complex disease such as Alzheimer’s brain insults result not from a single cause but from multiple pathological processes, we explored the protective effects of pantethine, a low-molecular-weight, multifunctional agent which has been shown to exert protective effects in several neurodegenerative diseases through multiple convergent mechanisms. In our study, pretreatment of astrocytes and treatment of mice with pantethine moderated age-related alterations. Moreover, it enhanced HIF-1α expression via the modulation of the Krebs’ cycle and proteasomal activities. In addition, a genome wide transcriptomic analysis from hippocampus samples of 5xFAD mice showed that pantethine attenuated most of gene overexpression in transgenic vs WT mice.In conclusion, we found that neuroinflammation lays at the root of Alzheimer’s disease pathological process and is also present in aging mice. Pantethine, this natural and well-tolerated compound could therefore prevent the disease development and temper the deleterious aging effects
Erta, Cañabate Maria. "Role of astrocytic IL-6 and IL-6R in normal physiology and neuroinflammation." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/275952.
Full textInterleukin-6 (IL-6) is a highly plurifunctional cytokine, with many pleiotropic actions, considered one of the main cytokines controlling the immune system and coordinating it with the nervous and endocrine systems. IL-6 is produced in multiple cell types in the central nervous system (CNS), and in turn many cells do respond to it. It is therefore important to ascertain which the contribution of each cell type is in the overall role of IL-6, during both physiological and pathological conditions. As astrocytes are major responders to IL-6 as well as one of the main CNS producers of IL-6, we have produced for the first time mice with astrocyte-derived IL-6 deficiency (Ast-IL-6 KO mice) and mice with deletion of IL-6 receptor in astrocytes (Ast-IL-6R KO mice). Our results indicate that astrocyte IL-6 system influenced the early survival, presumably due to intrauterine death, and was also involved to various degrees in the control of adult body weight and behavior (such as locomotor activity, anxiety, exploration, aggressiveness, learning and memory), among others. Also, in order to test its role during neuroinflammation, we studied an extensively used animal model of Multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), and a traumatic brain injury model (cryolesion) in Ast-IL-6 KO and Ast-IL-6R KO mice. Regarding EAE, results indicate that lack astrocytic IL-6 and IL-6R deficiency did not fully prevent EAE's prototypical ascending paralysis course but they modified its symptomatology in a gender-dependent manner. Regarding traumatic injury to the cortex, preliminary results obtained suggest a role of astrocytic IL-6 deficiency in traumatic brain injury resolution. In some occasions deleting IL-6R in astrocytes mimicked the phenotype of Ast-IL-6 KO mice, while in others the opposite was observed, suggesting autocrine and paracrine roles of astrocytic IL-6. Our results suggest important roles of the astrocyte IL-6 system, in some cases totally unexpected from previous results with animals with total deletion in IL-6 (IL-6 KO mice). Finally, as IL-6 is able to signal without binding to the membrane bound mIL-6R but by binding to a soluble receptor (sIL-6R) (trans-signaling), it is necessary to assess the importance of this pathway in mediating IL-6 actions in CNS. Bigenic mice (GFAP-IL6/sgp130 mice) with astrocyte-targeted production of IL-6 and coproduction of the specific inhibitor of IL-6 trans-signaling, human sgp130 were studied. Blockade of trans-signaling in the CNS reduced many of the detrimental effects that IL-6 have in the GFAP-IL-6 mice model of neuroinflammation; such as the severity of the gliosis, vascular alterations, impaired neurogenesis and neurodegeneration.
Shanaki, Bavarsad Mahsa. "Astrocyte-targeted production of IL-10 reduces the neuroinflammatory response associated to TBI and improves neurodegeneration." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/670855.
Full textLa inflamación es esencial en las respuestas a las infecciones y daños periféricos. Se pueden obtener beneficios de la inflamación si se controla durante un período de tiempo definido. La inflamación no regulada, sostenida o excesiva es la causa principal de diferentes neuropatologías. En el sistema nervioso central (SNC), la respuesta neuroinflamatoria cerebral tras una lesión cerebral traumática (TBI) se ha caracterizado en pacientes y en diferentes modelos animales experimentales como una de las principales causas de lesiones secundarias que conducen a la degeneración neuronal. La neuroinflamación se caracteriza por la activación de células gliales, el reclutamiento de leucocitos y la regulación y secreción de citocinas y mediadoras de quimiocinas. Además, la deficiencia de la barrera hematoencefàmica (BBB) tiene un papel importante en el tiempo agudo después del TBI, permitiendo la entrada de neutrófilos, monocitos y linfocitos T en el lugar de la lesión, afectando así la muerte neuronal. En diferentes estudios se ha demostrado el papel crucial de las citocinas antiinflamatorias en la reducción de las respuestas neuroinflamatorias. En este contexto, el objetivo de la presente tesis doctoral era caracterizar los efectos de la producción local de IL-10 sobre la respuesta neuroinflamatoria característica del TBI. Para conseguir este modelo la lesión criogénica de TBI se aplicó a animales transgénicos que producían IL-10 bajo el promotor de [astrocitos GFAP (animales GFAP-IL10Tg) y sus homólogos de tipo salvaje, y se analizaron diferentes características de la respuesta neuroinflamatoria. Este trabajo reveló que IL-10 promueve la supervivencia de las neuronas en las primeras horas después de lesionarse mediante la inhibición de la activación de células glía, el reclutamiento de neutrófilos, la interrupción del BBB y los niveles de expresión de la citoquina proinflamatoria IL-1β, asociada a la infiltración aumentada de los linfocitos T. Estos resultados señalan IL-10 como buen candidato para mejorar la respuesta neuroinflamatoria después del TBI y evitar daños secundarios en el tejido cerebral.
Inflammatory is essential in responses to peripheral infections and damage. Benefits of inflammation can be achieved if this phenomenon is controlled and for a defined period of time. Unregulated, sustained or excessive inflammation is the major cause of different neuropathologies. In the central nervous system (CNS), cerebral neuroinflammatory response after traumatic brain injury (TBI) has been characterized in patients and in different experimental animal models as one of the main causes of secondary injury leading to neuronal degeneration. Neuroinflammation is characterized by glial cell activation, leukocyte recruitment, and upregulation and secretion of cytokines and chemokines mediators. In addition, blood brain barrier (BBB) impairment has an important role in the acute time after TBI, allowing the entry of circulating neutrophils, monocytes, and T lymphocytes to the site of injury, and thus affecting neuronal death. In different studies the crucial role of anti-inflammatory cytokines in reduction of neuroinflammatory responses have been demonstrated. In this context, the objective of the present PhD was to characterize the effects of local production of IL-10 on the neuroinflammatory response characteristic of TBI. To achieve that cryogenic lesion model of TBI was applied to transgenic animals producing IL-10 under the astrocytic promoter GFAP (GFAP-IL10Tg animals) and their wild type counterparts, and different features of the neuroinflammatory response analyzed. This work revealed that IL-10 promotes the survival of neurons in the early hours after injury by inhibiting glia cell activation, neutrophil recruitment, disruption of BBB and the expression levels of the proinflammatory cytokine IL-1β, associated with increased T lymphocytes infiltration. These results point to IL-10 as a good candidate to ameliorate the neuroinflammatory response after TBI and prevent secondary tissue damage.
Herber, Donna Lorraine. "Neuroinflammation in Alzheimer’s Disease: Characterization and Modification of the Response of Transgenic Mice to Intrahippocampal Lipopolysaccharide Administration." Scholar Commons, 2004. https://scholarcommons.usf.edu/etd/1076.
Full textWang, Hui Hsin, and 王卉欣. "Reactive responses of astrocytes to pro-inflammatory mediators during neuroinflammation." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/52176794954952954694.
Full text長庚大學
生物醫學研究所
98
Emerging evidence suggests that astrocytes undergo large morphologic and gene expression changes in response to central nervous system (CNS) injury. In the CNS pathology, uncontrolled metalloproteinase-9 (MMP-9) activity and nitric oxide (NO) production are implicated in the increase of blood–brain barrier (BBB) permeability, the entry of leukocytes into the CNS, and sustained inflammatory responses. After traumatic and ischemic brain insults, disruption of the BBB raises the possibility of exposing the CNS to oxidized low-density lipoprotein (oxLDL), a risk factor implicated in neurodegenerative diseases. Hypoxic/ischemic injury also elicits endothelin-1 (ET-1) release in the CNS, behaving through G-protein coupled ET receptors. However, the detailed mechanisms of oxLDL and ET-1 action related to MMP-9 and iNOS expression and NO release on rat brain astrocytes remain largely unknown. Thus, this thesis focuses on investigating the signaling pathways by which oxLDL and ET-1 induced MMP-9 and iNOS expression and the functional consequences in astrocytes. Our results concluded that up-regulation of MMP-9 and iNOS induced by oxLDL and ET-1 may contribute to reactive responses of astrocytes after brain insults. First, the mechanisms underlying oxLDL-induced MMP-9 expression were investigated. We found that oxLDL induces expression of proMMP-9 via a mitogen-activated protein kinase (MAPK)-dependent activator protein-1 (AP-1) activation in rat brain astrocyte (RBA)-1 cells. Results revealed by gelatin zymography, RT-PCR, and Western blotting analyses showed that oxLDL-induced proMMP-9 gene expression was mediated through Akt, c-Jun N-terminal kinase (JNK1/2), and p42/p44 MAPK phosphorylation in RBA-1 cells. Moreover, the regulation of MMP-9 gene transcription by AP-1 was confirmed by chromatin immunoprecipitation (ChIP) assay which indentified the in vivo binding of c-Fos and c-Jun to the MMP-9 promoter, and by MMP-9 luciferase activity which was totally lost in cells transfected with the AP-1 binding site-mutated MMP-9 promoter construct (mt-AP1-MMP-9). These results suggest that oxLDL-induced proMMP-9 expression is mediated through phosphoinositide 3-kinase (PI3-K)/Akt, JNK1/2, and p42/p44 MAPK leading to AP-1 activation. Next, the roles of protein kinase C- (PKC-) and p42/p44 MAPK/Elk-1 cascades in oxLDL-induced MMP-9 expression were investigated. OxLDL induced MMP-9 expression via a PKC-/p42/p44 MAPK-dependent Elk-1 activation in RBA-1 cells. In vivo binding of Elk-1 to the MMP-9 promoter was evaluated by ChIP assay, revealing that oxLDL stimulated a time-dependent increase in binding of Elk-1 and p300 histone acetyltransferase (HAT), and sequential acetylated histone-4 to the MMP-9 promoter. Elk-1-mediated MMP-9 gene transcription was confirmed by transfection with an Elk-1 binding site-mutated MMP-9 promoter construct (mt-Ets-MMP9), which blocked oxLDL-stimulated MMP-9 luciferase activity. For astrocytic migration, the results suggested that the PKC-/p42/p44 MAPK/Elk-1-dependent proMMP-9 up-regulation is essential for the initiation of cell migration by oxLDL in RBA-1 cells. Furthermore, the participation of Elk-1, nuclear factor-κB (NF-B), and AP-1 in ET-1-induced proMMP-9 expression was proved. The data showed that ET-1-induced proMMP-9 expression was mediated through an ETB-dependent transcriptional activation. Engagement of Gi/o- and Gq-coupled ETB receptor by ET-1 led to activation of p42/p44 MAPK and then activated transcription factors including Elk-1, NF-B, and AP-1 (c-Jun/c-Fos). These activated transcription factors translocated into nucleus and bound to their corresponding binding sites in MMP-9 promoter, thereby turning on MMP-9 gene transcription. Functionally, up-regulation of proMMP-9 by ET-1 enhanced the migration of astrocytes. Taken together, these results suggested that in astrocytes, activation of Elk-1, NF-B, and AP-1 by ETB-dependent p42/p44 MAPK signaling is necessary for ET-1-induced MMP-9 gene up-regulation. Moreover, we demonstrated that exposure of astrocytes to ET-1 results in the iNOS up-regulation, NO production, and MMP-9 activation in astrocytes. Our data showed that ET-1-induced iNOS expression and NO production were mediated through an ETB-dependent transcriptional activation. ET-1 exerted the activation of c-Src-dependent PI3K/Akt and p42/p44 MAPK and NF-B, thereby promoting iNOS gene transcription. Sequential NO production enhanced astrocytic migration through the tyrosine nitration of MMP-9. These results suggested that in astrocytes, activation of NF-B by ETB-dependent c-Src, PI3K/Akt, and p42/p44 MAPK signalings is necessary for ET-1-induced iNOS gene up-regulation. Inclusion, we provide the mechanisms of oxLDL and ET-1 action on astrocytes, supporting the hypothesis that oxLDL and ET-1 contribute to the migration of astrocytes and the increased NO level involved in expression of MMP-9 leading to the development of CNS diseases. Understanding the mechanisms of MMP-9 and iNOS expression and functional changes regulated by oxLDL and ET-1/ETB system on astrocytes may provide rational therapeutic interventions for brain injury associated with the increased levels of MMP-9, iNOS, and NO.
Ribeiro, Antónia Sofia Fortunato. "Exploring the expression of NLRP3 inflammasome in reactive astrocytes." Master's thesis, 2019. http://hdl.handle.net/10316/90067.
Full textNeuroinflammation is an essential mechanism of innate immune defense in the CNS, but when unregulated it has been associated with the onset and progression of several pathologies, as neurodegenerative diseases. Astrocytes and microglia are the main immune effectors of the CNS and can become reactive when brain homeostasis is disrupted. In this way, these cells can contribute to the development of an inflammatory environment through the secretion of pro-inflammatory cytokines, like IL-1beta. Furthermore, astrocytes and microglia are in constant communication and can regulate each-other’s activity. Specifically, reactive microglia can secrete factors that induce a pro-inflammatory phenotype in astrocytes, the A1 phenotype.The main mechanism of IL-1beta production and secretion it’s the NLRP3 inflammasome, a multiprotein cytosolic complex that senses interferences in cell homeostasis. This inflammasome is activated through a two-step mechanism: a priming stimulus (like LPS), which induces an increased production of NLRP3 protein and pro-IL-1beta, and a second stimulus (like ATP), responsible for inflammasome oligomerization and consequent maturation and secretion of IL-1beta. The NLRP3 inflammasome assembly is well established in microglia, but it’s presence in astrocytes remains controversial.This project aimed to characterize NLRP3 inflammasome expression and function in A1 astrocytes and assess the role of microglia in these events. For this purpose, primary cultures of astrocytes isolated from newborn Sprague-Dawley rats were used. After 19 days in vitro, pure astrocytic cultures were incubated with LPS (100 ng/mL), ATP (1mM) or both. To simulate microglia signaling, astrocytes were also stimulated with a cocktail of factors: TNF-alpha (30 ng/mL), IL-1alpha (3 ng/mL) and C1q (400 ng/mL).Our results show that under LPS/ATP stimulation, astrocytes become reactive and secrete IL-1beta, mostly through NLRP3 inflammasome activity. Furthermore, TNF-alpha, IL-1alpha and C1q, besides activating astrocytes, act as a priming event capable of inducing NLRP3 and pro-IL-1beta production. However, astrocytes still require a second stimuli (as ATP) for inflammasome oligomerization and subsequent cytokine maturation.Overall, our work shows a preponderant role for astrocytes during neuroinflammation and reinforce the importance of microglia-astrocytes communication for CNS homeostasis and pathology.
A neuroinflamação é um mecanismo essencial do sistema imunitário inato no Sistema Nervoso Central, mas, quando desregulada, está associada ao desenvolvimento e progressão de várias patologias, como as doenças neurodegenerativas. Os astrócitos e a microglia são os principais efetores imunitários do SNC e têm a capacidade, quando há disrupções na homeostasia cerebral, de se tornarem reativos. Desta forma, estas células contribuem para o desenvolvimento de um ambiente inflamatório no SNC através da secreção de citocinas pro-inflammatórias, como a IL-1beta. Para além disto, os astrócitos e a microglia encontram-se em constante comunicação e podem regular a sua atividade mutuamente. Mais especificamente, a microglia reativa pode secretar fatores que induzem um fenótipo pro-inflamatório nos astrócitos, o fenótipo A1.O principal mecanismo de produção e secreção de IL-1beta é o inflamassoma NLRP3, um complexo citosólico multiproteico que deteta interferências na homeostasia celular. O inflamassoma é ativado através de dois passos: primeiro, um estímulo de priming (como LPS) induz um aumento na produção da proteína NLRP3 e de pro- IL-1beta. Um segundo estímulo (como ATP) induz a oligomerização do inflamassoma e consequente maturação e secreção de IL-1beta. Sabe-se que a microglia consegue expressar o inflamassoma NLRP3 ativo, mas a presença deste em astrócitos ainda é debatida.Este projeto tem como objetivo caracterizar a expressão e as funções do inflamassoma NLRP3 em astrócitos A1 e determinar o papel da microglia nestes eventos. Para isto, culturas primárias de astrócitos foram isoladas de ratos Sprague-Dawley recém-nascidos. Após 19 dias in vitro, as culturas puras de astrócitos foram incubadas com LPS (100 ng/mL), ATP (1mM) ou ambos. Para simular os sinais secretados pela microglia, os astrócitos foram estimulados com um cocktail de fatores: TNF-alpha (30 ng/mL), IL-1alpha (3 ng/mL) e C1q (400 ng/mL).Os nossos resultados demonstram que, sob estimulação com LPS/ATP, os astrócitos tornam-se reativos e secretam IL-1beta, maioritariamente devido à atividade do inflamassoma NLRP3. Para além do mais, TNF-alfa, IL-1alfa e C1q ativam os astróctios, atuando como um estímulo de priming capaz, de induzir a produção de NLRP3 e pro-IL-1beta. No entanto, os astrócitos necessitam de um segundo estímulo (por exemplo, o ATP) para que ocorra oligomerização do inflamassoma e consequente maturação de citocinas.Em resumo, este trabalho demonstra o papel preponderante dos astrócitos na neuroinflamação e reforça a importância da comunicação microglia-astrócitos para a homeostasia e patologia no SNC.
Outro - Project FCT, PTDC/MED-FAR/30933/2017
Wasserman, Jason. "Targeting Inflammation to Reduce Secondary Injury after Hemorrhagic Stroke." Thesis, 2008. http://hdl.handle.net/1807/11274.
Full textSequeira, Catarina Antunes. "Exploring A1 activation and miR-155 modulation in ALS spinal cord astrocytes." Master's thesis, 2018. http://hdl.handle.net/10362/52581.
Full textKalynovska, Nataliia. "Úloha angiotenzinových receptorů v modelu neuropatické bolesti." Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-310569.
Full textFerreira, Sofia Gravanita. "Differences in AD astrocyte phenotypes and responses to microglial-derived cytokines." Master's thesis, 2018. http://hdl.handle.net/10362/52582.
Full textChastre, Anne. "Le rôle de l’inflammation dans le développement des complications neurologiques associées à l’insuffisance hépatique aiguë chez la souris." Thèse, 2012. http://hdl.handle.net/1866/9886.
Full textAcute liver failure (ALF) is the clinical manifestation of an abrupt loss of hepatic function resuting from a massive hepatocyte necrosis in a patient with no preexisting liver disease. ALF is associated with metabolic and immunological disturbances that may lead to peripheral and cerebral complications such as systemic inflammatory response syndrome (SIRS), hepatic encephalopathy (HE), brain edema, increased intracranial pressure (ICP) and ultimately death by cerebral herniation. ALF is frequently complicated by infections, which are known to increase the risk of developing a SIRS with a subsequent worsening of HE and higher mortality rates. Ammonia plays a pivotal role in the pathophysiological mechanisms leading to HE and brain edema, and recent studies suggest that pro-inflammatory cytokines may also be involved. The aim of this thesis is therefore to investigate the role of circulating and cerebral pro-inflammatory cytokines in the setting of HE and brain edema during ALF. In article No. 1, we demonstrated that peripheral inhibition of tumor necrosis factor-alpha (TNF-α) by etanercept delays the progression of HE by reducing hepatocellular damage, decreasing peripheral and cerebral inflammation as well as associated oxidative/nitrosatif stress in mice with ALF induced by azoxymethane (AOM). These findings demonstrate an important role of TNF-α in the pathophysiology of HE during toxic liver injury and suggest that etanercept may provide a therapeutic approach in the management of patient awaiting liver transplantation. In article No. 2, we mimicked infection in mice with AOM-induced ALF in order to better understand the effects of an increased inflammatory response. We demonstrated that endotoxemia induced by lipopolysaccharide (LPS) precipitates the onset of coma and worsens the liver pathology. Peripheral and brain pro-inflammatory cytokines are synergistically raised by LPS during ALF and result in a large increase in cerebral matrix metalloprotease-9 (MMP-9) activity that was associated with immunoglobulin G (IgG) extravasation in the brain parenchyma. These results demonstrate a major increase of blood-brain barrier (BBB) permeability that contributes to the pathogenesis of HE during ALF with superimposed infection. Results from article No. 3 demonstrate that increase of BBB permeability during AOM-induced ALF without superimposed infection is not due to alteration of BBB constitutive proteins. In article No. 4, we demonstrated that exposure of cultured astrocytes to pathophysiological concentrations of ammonia or interleukin-1β results in an alteration of the expression of astrocytic genes implicated in cell volume regulation and oxidative/nitrosative stress. An additive effect on astrocytic genes implicated in oxidative/nitrosative was made evident in case of co-treatment. Taken together, results of the present thesis demonstrate a major role of peripheral and cerebral inflammation in the onset of neurological complications during ALF and a better understanding of the pathophysiological mechanisms implicated may contribute to new therapeutic strategies for ALF patients awaiting transplantation.
Neves, Sofia Pereira. "Studying the role of lipocalin-2 in the pathophysiology of multiple sclerosis: looking beyond the brain." Master's thesis, 2015. http://hdl.handle.net/1822/47233.
Full textMultiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system (CNS), characterized by the presence of demyelination plaques, inflammation and gliosis that consequently lead to axonal damage. The sequence of events that leads to demyelination remains unclear and the pathophysiological mechanisms are diverse. Also, although this is a disease of the CNS, there is no doubt that, in terms of peripheral organs, the thymus, as the organ of T cell differentiation and maturation, plays an important role in the pathophysiology of the disease. Recently, the levels of lipocalin 2 (LCN2), an acute phase protein that is part of the defense system against bacteria, by binding to iron-loaded siderophores, were found to be increased in cerebrospinal fluid (CSF) and serum of MS patients, when compared to control subjects. Similarly, using the MS animal model of experimental autoimmune encephalomyelitis (EAE), LCN2 was detected in brain parenchyma astrocytes, in regions typically affected in MS patients. This expression by astrocytes, together with an increased LCN2 level in the CSF, occurs during the active phases of the disease, which could point towards a role for LCN2 secreted by astrocytes in the mediation of inflammatory responses in the EAE model. Altogether, these findings support LCN2 as a valuable molecule for the diagnostic/monitoring of MS and suggest its potential involvement as a disease modulator. Of relevance, the exact role of LCN2 in the pathophysiology of the disease remains largely unknown and contradictory data exists on its potential protective or deleterious effect. Therefore, we sought to investigate the role of LCN2 in the onset and progression of the disease. Herein, we tackled the disease, by evaluating the role of LCN2, not only in the perspective of the CNS, but also on the perspective of peripheral organs such as the thymus. First we intended to perform a characterization of the thymus regarding thymocyte populations and histological morphology, in wild-type (WT) animals induced with EAE, in the onset and chronic phases of disease. Next, to further understand the role of LCN2 in MS pathology, we induced EAE both in LCN2- null mice and in WT littermates. Non-induced EAE animals were used as controls. The thymus of EAE animals was atrophied, as assessed by its weight, normalized for total body weight, and by the number of total cells. Also, we found a decrease in total cell number of all thymocyte populations, during the onset and chronic phases of EAE. In relative terms, the percentage of double positive cells was decreased, and the percentages of the cluster of differentiation (CD)4 and CD8 single positive cells were increased, during the onset phase. At the chronic phase, the proportions between the different populations were restored. LCN2-null mice induced with EAE did not present major alterations in terms of the clinical score, when compared with WT littermates also induced with EAE. Likewise, their thymic alterations were similar to the ones observed in WT EAE animals. Of relevance, as for the inflammatory profile in the cerebellum, LCN2-null mice presented less inflammation, as assessed by decreased expression levels of proinflammatory cytokines interferon (Ifn)-gamma, interleukin (Il)12a and Il17a. Also of interest, the cerebellum of LCN2-null mice presented a decrease in the percentage of lesioned areas. Finally, EAE animals, from both genotypes, presented an increase in the area positive for glial fibrillary acidic protein (GFAP), in the white matter of the cerebellum, in both the onset and chronic phases of disease. On the contrary, the expression levels of Gfap in the cerebellum were only increased at the onset phase of disease.
A Esclerose Múltipla (EM) é uma doença autoimune desmielinizante do sistema nervosa central (SNC), caracterizada pela presença de placas de desmielinização, inflamação e gliose, que tem como consequência dano axonal. A sequência de eventos que induzem desmielinização permanecem desconhecidos, e os mecanismos patofisiológicos são diversos. Embora esta seja uma doença do SNC, não há dúvidas que, em termos de órgãos periféricos, o timo, sendo o órgão de maturação e diferenciação das células T, desempenha um papel importante na patofisiologia da doença. Recentemente, os níveis de lipocalin-2 (LCN2), uma proteína de fase aguda que participa no sistema de defesa contra infeções bacterianas, através da ligação a sideróforos, foram encontrados como estando elevados no líquido cefalorraquidiano (LCR) e no soro de doentes com EM, comparativamente aos controlos. Da mesma maneira, usando o modelo animal de EM de encefalomielite autoimune experimental (EAE), a LCN2 foi detetada em astrócitos do parênquima, em regiões tipicamente afetadas em doentes com EM. Esta expressão pelos astrócitos, associada a um aumento de LCN2 no LCR, ocorreu durante as fases ativas da doença, o que aponta para um papel da LCN2 secretada pelos astrócitos na mediação da response inflamatória no modelo de EAE. No seu conjunto, estas evidências suportam o papel da LCN2 como uma molécula importante no diagnóstico e/ou monitorização da EM, e sugere o seu possível envolvimento como moduladora da doença. É relevante dizer que o papel exato da LCN2 na patofisiologia da doença permanece desconhecido, e existem dados contraditórios no que diz respeito ao seu potencial efeito protetor ou deletério. Por isso, nós procurámos perceber o papel da LCN2 no onset e na progressão da doença. Assim, nós investigámos o papel da LCN2 na doença, não só na perspetiva do SNC, mas também dos órgãos periféricos, nomeadamente do timo. Primeiro pretendemos caracterizar o timo em relação às populações de timócitos e morfologia histológica, em animais wild-type (WT) induzidos com EAE, no onset e na fase crónica da doença. De seguida, para melhor entender o papel da LCN2 na patologia da EM, induzimos EAE em animais LCN2- null e em WT da mesma ninhada. Para além disso, usámos animais não induzidos como controlos. Nós observámos que o timo dos animais induzidos com EAE estava atrofiado, com base no seu peso, após normalização para o peso total do animal, e no número total de células. Para além disso, encontrámos uma diminuição no número total de células de todas as principais populações de timócitos, durante o onset e fase crónica da doença. No que diz respeito à percentagem de cada uma das populações de timócitos, durante o onset da doença, a percentagem de células duplas positivas encontrava-se diminuída, enquanto as percentagens das populações CD4+CD8- e CD4-CD8+ se encontrava aumentada. Na fase crónica da doença, as proporções entre as diferentes populações foram reestabelecidas. Os animais LCN2-null induzidos com EAE não apresentaram grandes alterações em termos de score clínico, quando comparados com os animais WT da mesma ninhada também induzidos com EAE. Para além disso, as alterações observadas no timo foram semelhantes às encontradas nos animais WT EAE. De relevância, no que diz respeito ao perfil inflamatório no cerebelo, os animais LCN2-null apresentaram menos inflamação, o que é suportado por níveis diminuídos dos níveis de expressão das citoquinas pró-inflamatórias interferão-gama, e interleucinas 12 e 17. É importante também referir que os cerebelos de animais LCN2-null apresentaram uma diminuição na percentagem de áreas com lesões. Os animais EAE, de ambos os genótipos, apresentaram um aumento na área positiva para GFAP, na substância branca do cerebelo, no onset e na fase crónica da doença. Pelo contrário, os níveis de expressão de Gfap no cerebelo só foram encontrados elevados no onset da doença.
(10725291), Priya Prakash. "Characterizing Microglial Response to Amyloid: From New Tools to New Molecules." Thesis, 2021.
Find full textMicroglia are a population of specialized, tissue-resident immune cells that make up around 10% of total cells in our brain. They actively prune neuronal synapses, engulf cellular debris, and misfolded protein aggregates such as the Alzheimer’s Disease (AD)-associated amyloid-beta (Aβ) by the process of phagocytosis. During AD, microglia are unable to phagocytose Aβ, perhaps due to the several disease-associated changes affecting their normal function. Functional molecules such as lipids and metabolites also influence microglial behavior but have primarily remained uncharacterized to date. The overarching question of this work is, How do microglia become dysfunctional in chronic inflammation? To this end, we developed new chemical tools to better understand and investigate the microglial response to Aβ in vitro and in vivo. Specifically, we introduce three new tools. (1) Recombinant human Aβ was developed via a rapid, refined, and robust method for expressing, purifying, and characterizing the protein. (2) A pH-sensitive fluorophore conjugate of Aβ (called AβpH) was developed to identify and separate Aβ-specific phagocytic and non-phagocytic glial cells ex vivo and in vivo. (3) New lysosomal, mitochondrial, and nuclei-targeting pH-activable fluorescent probes (called LysoShine, MitoShine, and NucShine, respectively) to visualize subcellular organelles in live microglia. Next, we asked, What changes occur to the global lipid and metabolite profiles of microglia in the presence of Aβ in vitro and in vivo? We screened 1500 lipids comprising 10 lipid classes and 700 metabolites in microglia exposed to Aβ. We found significant changes in specific lipid classes with acute and prolonged Aβ exposure. We also identified a lipid-related protein that was differentially regulated due to Aβ in vivo. This new lipid reprogramming mechanism “turned on” in the presence of cellular stress was also present in microglia in the brains of the 5xFAD mouse model, suggesting a generic response to inflammation and toxicity. It is well known that activated microglia induce reactive astrocytes during inflammation. Therefore, we asked, What changes in proteins, lipids, and metabolites occur in astrocytes due to their reactive state? We provide a comprehensive characterization of reactive astrocytes comprising 3660 proteins, 1500 lipids, and 700 metabolites. These microglia and astrocytes datasets will be available to the scientific community as a web application. We propose a final model wherein the molecules secreted by reactive astrocytes may also induce lipid-related changes to the microglial cell state in inflammation. In conclusion, this thesis highlights chemical neuroimmunology as the new frontier of neuroscience propelled by the development of new chemical tools and techniques to characterize glial cell states and function in neurodegeneration.
Shao-MingWang and 王紹銘. "Investigation of astrocytic CEBPD-mediated anti-apoptosis and reactive oxygen species formation in neuroinflammation." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/sqcgza.
Full text國立成功大學
基礎醫學研究所
105
Neuroinflammation has been suggested to play a critical role in the pathogenesis of neurodegenerative disorders and central nervous system injury such as Alzheimer’s disease (AD) and spinal cord injury. Neuroinflammation can cause glia cell activation and produce inflammatory cytokines, especially astrocyte. Astrocytes are the principal cell type in the central nervous system (CNS) and are essential in normal brain tissue. They can secrete neurotrophic factors that support normal neuron function and survival. In contrast, astrocytes can be activated and cause inflammation in a neuroinflammatory environment. Further, activated astrocytes can cause astrogliosis, which is characterized by cell anti-apoptosis, proliferation and the migration of astrocytes, and eventually leads to scar formation. The CCAAT/enhancer binding protein delta (CEBPD) protein is an inflammatory transcription factor and participates in both chronic and acute inflammation in CNS. Previous studies have shown that the CEBPD protein contributes to expression of Alzheimer’s disease. However, its role in Alzheimer’s disease remains unclear. Our data show that CEBPD is highly expressed in astrocytes in AD mouse models. In AD, a lack of CEBPD in AppTg mice can decrease astrocyte activation and reduce ROS formation. Further, I found that astrocytic CEBPD can activate ZNF179 expression, and ZNF179 can interact with PLZF to repress pro-apoptosis gene expression, including IGFBP3 and BIK. Furthermore, astrocytic CEBPD can induce ROS formation through p47phox and p67phox expression. Cu/Zn superoxide dismutase (SOD1), an antioxidant enzyme, is also up-regulated by CEBPD in astrocytes, which may contribute to the astrocyte resistance in an oxidative stress. Taken together, astrocytic CEBPD contributes to astrogliosis, has pathogenic consequences in neuroinflammatory disease, and provides new insights into the functional role of CEBPD in astrocytes that may lead to novel therapeutic strategies for the treatment.
Canedo, Teresa Correia Soares. "Unveiling the cellular and molecular players involved in methamphetamine - induced neuroinflammation: focus on astrocyte - microglial crosstalk." Doctoral thesis, 2022. https://hdl.handle.net/10216/139356.
Full textClarkson, Melissa A. "Acute Astrogliosis and neurological deficits following repeated mild traumatic brain injury." Thesis, 2018. https://dspace.library.uvic.ca//handle/1828/10027.
Full textGraduate
Santos, Vanessa Filipa Coelho. "Effect of methylphenidate on blood-brain barrier function in health and attention deficit hyperactivity disorder." Doctoral thesis, 2018. http://hdl.handle.net/10316/79685.
Full textMethylphenidate (MPH) is an amphetamine-like psychostimulant that has become the primary drug of choice for treating attention-deficit hyperactivity disorder (ADHD), a highly prevalent neuropsychiatric disorder with an onset in early childhood. ADHD includes behavioral and cognitive symptoms, such as inattention and/or impulsivity/hyperactivity. In more than 50% of children with ADHD, the symptoms persist into adolescence and adulthood. Moreover, the diagnosis of ADHD itself is non-consensual and several reports claim that physicians tend to be preoccupied with reducing symptoms via medication but often fail to recognize the context in which the behavior exhibits, which suggest that ADHD is being overdiagnosed in children. Despite being beneficial under ADHD conditions, MPH misuse is nowadays a problem with high impact on society. The full comprehension of the cellular/molecular mechanisms trigger by MPH use is still elusive. To date, most of the studies that explain the underlying MPH effects on central nervous system have focused on intra-neuronal events, particularly on dopaminergic alterations. The impact of MPH on blood brain-barrier (BBB) function has never been addressed before neither in non-pathological conditions nor in ADHD. The BBB is a barrier highly selective responsible for the regulation and maintenance of brain homeostasis creating a proper microenvironment for neural function. Given the evidence of BBB damage as an early event in many neurological conditions, it is not surprising that there is a growing interest in the BBB as a therapeutic target. Thus, the major goal of the present thesis was to clarify the effects of MPH on the BBB function in both physiological and ADHD conditions. Specifically, we aimed to investigate the direct impact of MPH on human brain microvascular endothelial cells (HBMVECs), and to evaluate the effect of chronic MPH use during normal and ADHD rat neurodevelopmental on the neurogliovascular unit, brain immune surveillance neuroinflammation, and behavior. This thesis is organized in 5 chapters. In chapter 1 is presented a review of the literature about the topics explored in this work with emphasis in ADHD, MPH and BBB. In chapter 2, we evaluated the direct effect of MPH on HBMVEC. It was found that MPH increases brain endothelial cell permeability by promoting the vesicular transport. Specifically, we identified the molecular event critical to MPH-induced transcytosis, showing that c-Src is activated in result of intracellular reactive oxygen species generated by Rac1/NOX that interacts and phosphorylates Caveolin1, resulting in caveolae formation and consequent vesicular permeability. Next in chapter 3, we unraveled MPH chronic outcome in the healthy brain as well as cognitive concerns that might arise from its misuse. Since hippocampus is highly involved in memory/learning processes we focused on this brain region. Our data revealed that higher doses of MPH cause endothelial dysfunction and activation with a consequent increase of leukocyte infiltration by transcytosis. In addition to disruption of hippocampal vasculature, alterations in astrocytic morphology and synaptic machinery were also observed. These neurogliovascular disturbances culminated in memory deficit. Contrariwise, a lower dose of MPH improved cognition in parallel with an increase of astrocytic processes but with no major effect on BBB permeability. Furthermore, we showed that MPH misuse modulated AKT/CREB signaling pathway, which can explain alterations on cognitive performance. Afterwards, in chapter 4, we dissected the impact of early-life chronic consumption of MPH on brain immune surveillance and neuroinflammation in both physiological and ADHD conditions. This work was focused on the prefrontal cortex that is a brain region with a prominent role in the pathophysiology of ADHD. Our results show that chronic exposure to a higher dose of MPH caused BBB leakage and elicited an anxious-like behavior in both healthy and ADHD conditions. Nevertheless, BBB dysfunction was more prominent in control animals, which was proved by a downregulation and disruption of intercellular junctions, an increase of microvessels vesicles, and endothelium activation concomitant with infiltration of peripheral immune cells. Moreover, independently of the dose used, MPH triggered a robust oxidative and neuroinflammatory response in healthy rats shown by astrocytes and microglial cells activation and upregulation of pro-inflammatory cytokines. On the contrary, in ADHD animal model, MPH at the lower dose restored brain homeostasis by decreasing the inflammatory and oxidative status. Moreover, the MPH immune-modulatory effects in both animal conditions seem to be mediated through NF-κB/NLRP3 signaling pathways. Finally, in chapter 5, a general discussion with final remarks is presented. Overall, this thesis provides evidence that MPH acts directly on endothelial cells impairing BBB integrity, which may favor the access of peripheral cells into the brain. Additionally, MPH has an effect on glial cells leading to a neuroinflammatory response and oxidative status. Behavior alterations were also observed, including spatial working memory deficit and anxiety-like behavior. Herein, we improved our understanding about neurogliovascular unit alterations associated with chronic MPH treatment during development, and how these changes depend on the dose of MPH and (non)-pathological conditions, which highlights the importance of an appropriate MPH dose regimen for ADHD and an adequate diagnosis to avoid MPH misuse.
O metilfenidato (MFD) é um psicoestimulante do grupo das anfetaminas usado como primeira linha de tratamento da perturbação de hiperatividade e défice de atenção (PHDA). PHDA é uma perturbação neuropsiquiátrica altamente prevalente com inicio na infância e que inclui sintomas comportamentais e cognitivos, nomeadamente falta de atenção e/ou impulsividade/hiperatividade. Normalmente, em mais de 50% das crianças com PHDA os sintomas persistem até à adolescência e fase adulta. Além disso, o diagnóstico desta patologia não é consensual com vários relatórios a afirmar que os médicos tendem a estar mais preocupados com a redução dos sintomas através da medicação e muitas vezes não conseguem reconhecer o contexto em que o comportamento é exibido, o que sugere que a PHDA está a ser sobrediagnosticada em crianças. Apesar de ser benéfico em condições de PHDA, o uso indevido de MFD é hoje em dia um problema com alto impacto na sociedade. Os mecanismos celulares/moleculares desencadeados pelo uso de MFD ainda são largamente desconhecidos. Até à data, a maioria dos estudos que explicam os efeitos no sistema nervoso central subjacentes ao uso do MFD têm-se focado nos eventos intraneuronais, particularmente nas alterações dopaminérgicas. Neste sentido, o impacto do MFD na função de barreira hematoencefálica (BHE) nunca foi abordado antes, quer em condições não patológicas quer em situações de PHDA. A BHE é uma barreira altamente seletiva responsável pela regulação e manutenção da homeostasia cerebral, criando um microambiente adequado para a função neuronal. Visto que a disfunção na BHE é considerada um evento precoce em muitas patologias do cérebro, não é surpreendente que haja um interesse crescente na BHE como um alvo terapêutico. Desta forma, o principal objetivo da presente tese foi esclarecer os efeitos do MFD na função da BHE em condições fisiológicas e de PHDA. Especificamente, pretendeu-se investigar o efeito direto do MFD nas células endoteliais da microvasculatura do cérebro humano (CEs) e avaliar o efeito do uso crónico de MFD durante o desenvolvimento neurológico normal e numa condição de PDHA, tendo como principais focos a unidade neurogliovascular, a resposta imunitária e neuroinflamatória, bem como as alterações comportamentais. Esta tese encontra-se organizada em 5 capítulos. No capítulo 1, é apresentada uma revisão da literatura onde se exploram tópicos essenciais à compreensão deste trabalho dando ênfase à PHDA, MFD e BHE. No capítulo 2, avaliamos o efeito direto do MFD nas CEs. Verificou-se que o MFD aumenta a permeabilidade das CEs promovendo o transporte vesicular. Especificamente, identificámos a via de sinalização intracelular responsável pela transcitose induzida por MFD, mostrando que a c-Src é ativada por espécies reativas de oxigénio intracelular gerados pelo complexo Rac1/NOX que por sua vez interage e fosforila a caveolina 1, resultando na formação de cavéolas e consequente permeabilidade vesicular. Em seguida, no capítulo 3, desvendámos os efeitos resultantes do consumo crónico do MFD no cérebro saudável, bem como as consequências cognitivas que podem surgir do seu uso indevido. Tendo em consideração que o hipocampo está amplamente envolvido em processos de memória/aprendizagem, focámos o nosso estudo nesta região cerebral. Concluímos que doses mais altas de MFD causam disfunção e ativação endotelial com o consequente aumento da infiltração de leucócitos por transcitose. Além da disfunção da vasculatura do hipocampo, também foram observadas alterações na morfologia dos astrocítos e na maquinaria sináptica. Estas alterações neurogliovasculares culminaram em défice de memória. Por outro lado, uma menor dose de MFD melhorou a memória em simultâneo com um aumento dos prolongamentos astrocíticos, mas sem efeito significativo na permeabilidade da BHE. Adicionalmente, mostrámos que o uso indevido do MFD é capaz de modular a via de sinalização da AKT/CREB, o que pode explicar as alterações no desempenho cognitivo. Posteriormente, no capítulo 4, avaliámos o impacto do consumo crónico de MFD no período correspondente desde a infância até à adolescência tardia na vigilância imunológica do cérebro e na neuroinflamação em condições fisiológicas e de PHDA. Este trabalho foi focado no córtex pré-frontal, região cerebral com um papel proeminente na fisiopatologia da PHDA. Os nossos resultados mostram que a exposição crónica a uma dose mais elevada de MFD causou um aumento da permeabilidade da BHE e incitou um comportamento do tipo ansioso em ambas as condições estudadas, saudável e PHDA. No entanto, a disfunção da BHE foi mais proeminente nos animais sem patologia, o que foi evidenciado por uma diminuição dos níveis e rutura das junções intercelulares, um aumento de vesículas nos microvasos e ativação do endotélio, concomitante com a infiltração de células do sistema imunitário periférico para o cérebro. Para além disso, independentemente da dose utilizada, o MFD desencadeou uma resposta oxidativa e neuroinflamatória robusta nos ratos saudáveis comprovado pela ativação dos astrócitos e das células da microglia, assim como pelo aumento de citocinas pró-inflamatórias. Pelo contrário, no modelo animal de PHDA, o MFD na dose mais baixa restaurou a homeostasia cerebral, diminuindo o estado inflamatório e oxidativo. Além disso, os efeitos imunomoduladores do MFD em ambos os modelos animais parecem ser mediados pela via de sinalização do NF-κB/NLRP3. Finalmente, no capítulo 5, uma discussão geral com considerações finais é apresentada. Em conclusão, esta tese dá-nos evidências de que o MFD atua diretamente nas CEs prejudicando a integridade da BHE, o que pode favorecer o acesso das células periféricas ao cérebro. De realçar que o MFD tem também um efeito nas células da glia, desencadeando uma resposta neuroinflamatória e causando stress oxidativo. Alterações comportamentais também foram observadas, incluindo défice de memória de trabalho e comportamento do tipo ansioso. Desta forma, contribuímos para uma melhor compreensão das alterações que ocorrem na unidade neurogliovascular devido a um tratamento crónico com MFD durante o desenvolvimento numa condição fisiológica versus PHDA, e como essas alterações dependem ainda da dose de MFD. Estas observações evidenciam a importância da dose terapêutica de MFD que é prescrita e de um diagnóstico mais objetivo para evitar o uso indevido de MFD.
FCT - PTDC/NEU-OSD/0312/2012 (COMPETE e FEDER ) ; Pest-C/SAU/UI3282/2013-2014 e CNC.IBILI UID/NEU/04539/2013 ; PT2020/COMPETE 2020 e Operational Program for Competitiveness and Internalization (POCI) - FCOMP-01-0124-FEDER-028417 e POCI-01-0145-FEDER-007440
Leitão, Ricardo Alexandre Gomes. "Role of aquaporin-4 in methamphetamine-induced blood-brain barrier dysfunction and cerebral edema formation." Doctoral thesis, 2017. http://hdl.handle.net/10316/40920.
Full textMethamphetamine (METH) is a powerful psychostimulant drug of abuse that has gained worldwide popularity, and its use originates severe health problems. Despite extensive characterization of METH-induced neurotoxicity over the last years, many questions remain unanswered. Several reports have demonstrated that oxidative stress, mitochondrial dysfunction, and neuroinflammation are some of the neurotoxic features of METH. More recently, it was shown that METH compromises the blood-brain barrier (BBB) and causes a disturbance in the water homeostasis leading to brain edema. Additionally, it is well known that astrocytes play a crucial role in modulating BBB structure and function, as well as in regulating brain water content. However, the effect of METH on the crosstalk between brain endothelial cells (ECs) and astrocytes has never been addressed before. Also, water fluxes that take place between the different compartments of the brain, and between brain parenchyma and the blood are highly controlled. Thus, disturbances in this well-regulated homeostasis cause brain edema, which will have deleterious effects on brain function. Importantly, the water transport at BBB is regulated by water channels, aquaporins (AQPs), and AQP4 is the most important at the Central Nervous System, being express on astrocytic endfeet in contact with brain vessels. Brain edema is a hallmark of several neuropathologies, and METH consumption is not an exception. Yet, to date, nothing is known about the role of AQP4 under METH conditions. Furthermore, AQP4 has two isoforms, M1 and M23, and the ratio M1/M23 regulates water homeostasis since M23 stabilizes the channel function but M1 disrupts the AQP4 structure. Taking into consideration all the gaps in this field, it is urgent to clarify the role of AQP4 in METH-induced BBB dysfunction and brain edema formation. The present thesis is divided into 5 chapters. In chapter 1 is presented a review of the literature about the different themes that were explored in the laboratory and detailed in the following chapters. In chapter 2, the impact of METH on astrocytes-ECs crosstalk was investigated with a particular interest in the role of tumor necrosis factor alpha (TNF-α). After observing that METH increased TNF-α released by both astrocytes and ECs, it was also proved that this proinflammatory cytokine was responsible for endothelial permeability through the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. These in vitro results were corroborated by animal studies showing an increase of BBB permeability and TNF-α levels in the mice striatum, which was prevented by NF-κB pathway blockade. Overall, it was shown that TNF-α/NF-κB signaling pathway has a key role in METH-induced BBB dysfunction. Next, in chapter 3, it was investigated the direct effect of METH on AQP4 system concluding that METH, besides BBB dysfunction, is also able to induce a cytotoxic brain edema and depressive-like behavior. Curiously, AQP4 was shown to have a predominant role of such alterations since its inhibition prevented all the effects observed in mice. Moreover, AQP4 via reactive oxygen species (ROS) production was involved in cell swelling and altered astrocyte morphology triggered by METH since AQP4 knockdown or its pharmacological blockade, as well as an antioxidant treatment (namely vitamin C) were able to prevent METH effects in astrocytes. In conclusion, AQP4 was identified as a new target against METH-induced neurogliovascular dysfunction and depressive-like behavior. Following the results observed in chapter 2 and 3, a new strategy to counteract the negative effects of METH was applied by using a natural flower product. Thus, in chapter 4, it was proved that parthenolide (PTL), a feverfew plant extract, has an anti-inflammatory role and prevented METH-induced BBB permeability and brain edema. Additionally, TNF-α via activation of its receptor 1 (TNFR1) was involved in astrocytic swelling induced by METH. In sum, PTL plays a beneficial role against neuroinflammation and neurogliovascular dysfunction triggered by METH. Finally, in chapter 5, a general discussion is presented. Overall, the present work shows that METH interferes with brain water homeostasis and BBB function, culminating in behavioral abnormalities. Moreover, both neuroinflammation and oxidative stress are involved in such negative effects of METH, and new strategies to counteract these deleterious consequences were identified, such as AQP4 blockade and the use of PTL.
A metanfetamina (MET) é uma droga de abuso muito viciante com grande popularidade mundial, e que causa sérios problemas de saúde. Apesar da extensa caracterização da sua neurotoxicidade nos últimos anos, muitas questões continuam sem resposta. Alguns estudos têm mostrado que o stresse oxidativo, a disfunção mitocondrial e a neuroinflamação são alguns dos efeitos nefastos da MET. Mais recentemente demonstrou-se que a MET interfere com a função normal da barreira hematoencefálica (BHE), causando alterações na homeostase da água o que pode levar a uma situação de edema cerebral. Para além disso, sabe-se também que os astrócitos têm um papel muito importante na modulação da estrutura e função da BHE, bem como na regulação do conteúdo de água cerebral. No entanto, o efeito da MET na comunicação entre as células endoteliais (CEs) e os astrócitos nunca foi estudado anteriormente. Por outro lado, o movimento de moléculas de água entre os diferentes compartimentos do cérebro e entre o parênquima cerebral e a corrente sanguínea ocorre de forma controlada. Assim, distúrbios nesta homeostase irão causar uma situação de edema, o qual terá um impacto negativo na função cerebral. O transporte de água na BHE é regulado por canais de água, denominados aquaporinas (AQPs), sendo que a AQP4 é a mais importante no Sistema Nervoso Central, e encontra-se expressa nas terminações dos astrócitos que contactam com os vasos cerebrais. De facto, o edema cerebral ocorre em muitas neuropatologias, e o consumo de MET não é exceção. No entanto, o papel da AQP4 nos efeitos da MET é ainda desconhecido. Além disso, a AQP4 tem duas isoformas, a M1 e a M23, e é a sua proporção que regula a homeostase da água, uma vez que a presença da isoforma M23 estabiliza a função do canal de água enquanto a isoforma M1 causa alterações na função da AQP4. Deste modo, é importante esclarecer o papel da AQP 4 na disfunção da barreira hematoencefálica e na formação do edema cerebral induzidos por MET. A presente tese está dividida em 5 capítulos. No capítulo 1 é apresentada uma revisão da literatura sobre os diversos temas estudados no laboratório e detalhados nos capítulos seguintes. No capítulo 2 investigou-se o efeito da MET na comunicação entre astrócitos e CEs com particular interesse no papel do fator de necrose tumoral alfa (TNF-α). Depois de mostrar um aumento da libertação de TNF-α induzido por MET, quer pelos astrócitos quer pelas CEs, provou-se que esta citocina pró-inflamatória estava envolvida no aumento da permeabilidade das CEs através da ativação da via de sinalização do fator nuclear kappa B (NF-κB). Estes resultados foram corroborados por estudos em animais onde se observou um aumento da permeabilidade da BHE e dos níveis de TNF-α no estriado de murganho, efeitos estes que foram prevenidos pelo bloqueio da via do NF-κB. Deste modo, conclui-se que a via de sinalização do TNF-α/NF-κB está envolvida na disfunção da BHE induzida por MET. De seguida, no capítulo 3 avaliou-se o impacto direto da MET no sistema da AQP4 e foi possível demonstrar que esta droga de abuso, para além de induzir uma disfunção da BHE, também originou um edema cerebral citotóxico e comportamento do tipo depressivo. Curiosamente, a AQP4 teve um papel predominante nestas alterações já que o seu bloqueio preveniu todos os efeitos observados nos murganhos. In vitro foi também possível comprovar o papel importante da AQP4 via produção de espécies reactivas de oxigénio já que o silenciamento deste canal de água ou a sua inibição farmacológica, bem como a exposição a um antioxidante (vitamina C) preveniram as alterações morfológicas induzidas pela MET nos astrócitos. Em conclusão, a AQP4 foi identificada como um alvo importante para prevenir as alterações neurogliovasculares e comportamento depressivo induzidos por MET. Na sequência dos efeitos negativos da MET observados nos capítulos 2 e 3, colocou-se a hipótese de uma nova abordagem com um produto natural de origem vegetal. Deste modo, no capítulo 4 concluíu-se que o partenolídeo (PTL), um extrato obtido da artemísia dos prados (Tanacetum parthenium), tem um papel anti-inflamatório e preveniu o aumento da permeabilidade da BHE e formação de edema cerebral induzidos por MET. Mais ainda, foi possível demonstrar que o TNF-α, através da ativação do seu recetor TNFR1, estava envolvido no aumento de volume dos astrócitos observado na presença de MET. Assim, este trabalho permitiu concluir que o PTL tem um feito benéfico em condições de neuroinflamação e disfunção neurogliovascular induzidos por MET. Por último, o capítulo 5 inclui uma discussão geral sobre os resultados obtidos nos capítulos anteriores. Em conclusão, esta tese permitiu mostrar que a MET interfere não só com a homeostase da água no cérebro, mas também com a função da BHE, e que estes efeitos podem conduzir a alterações comportamentais. Para além disso, demonstrou-se ainda que a neuroinflamação e o stresse oxidativo estão subjacentes aos efeitos negativos causados pela MET e foram identificadas duas abordagens para prevenir estes efeitos, tais como o bloqueio da AQP4 e o uso do partenolídeo.
Meehan, Crystal Lea. "The role of early versus late gestational maternal immune activation in the aetiology of schizophrenia: establishing a rat model with a focus on cognitive symptomology and neuroinflammation." Thesis, 2018. http://hdl.handle.net/1959.13/1385728.
Full textSchizophrenia is a debilitating disorder of neurodevelopmental origins that likely stems from the cumulative action of a range of genetic and environmental factors. Epidemiological evidence has identified maternal infection during gestation as one significant environmental risk factor for the development of the disorder. Evidence from animal models has further validated the link between maternal immune activation (MIA) in the absence of an active infection and the later life development of schizophrenia-like pathology in the offspring. In particular, work in mouse models has suggested that the gestational time at which MIA occurs can alter the behavioural and neurobiological phenotype displayed. Specifically, that MIA in late gestation is involved in schizophrenia-relevant cognitive dysfunction and altered NMDA receptor expression, whereas MIA in early gestation is more closely associated with behavioural deficits reminiscent of positive symptomology and dopaminergic neurotransmission. The aim of the current thesis was to extend the mouse findings to another species, the rat, and further explore the effects of MIA. In addition to producing a reliable rat model of schizophrenia where distinct behavioural and neurological phenotypes associated with schizophrenia are produced following MIA at either early or late gestational time-points (gestational day 10 or 19, respectively), the current thesis extends on previous work by examining the schizophrenia biomarker of mismatch negativity and assessing the neuroinflammatory state of offspring. Behavioural assessments revealed that MIA in either early or late gestation produced transient impairments in working memory and reductions in PPI. In these behavioural studies, there was no clear distinction between a dopamine and glutamate-related behavioural phenotype based on the gestational timing of exposure. However, early but not late gestation MIA did produce alterations in the dopaminergic system of males, as indicated by increased dopamine 1 receptor mRNA in the nucleus accumbens. EEG experiments demonstrated that although the male rat brain is able to generate human-like (adaptation-independent) mismatch responses (MMRs), and although MIA (regardless of gestational timing) does alter MMRs, it does not do so in a manner comparable with schizophrenia. Immunohistochemical techniques revealed that MIA does result in subtle neuro-immune changes in adult offspring, with an increase in microglial immunoreactivity identified in the frontal white matter of late, but not early, gestation MIA animals. Furthermore, a strong trend towards increased astrocyte immunoreactivity that approached significance was identified in the prefrontal cortex of late, but not early MIA offspring. The combined results have demonstrated that MIA during the chosen gestational time-points are sufficient to disrupt neurodevelopmental processes producing long-term alterations in behavioural and neuropathological measures relevant to schizophrenia. However, the phenotype characterised here deviates slightly from previous findings from mouse models indicating potential differences in the critical periods of neurodevelopmental susceptibility to MIA exposure between the rat and mouse. Importantly this research has provided insights into the underlying neuro-immune changes which may contribute to the behavioural abnormalities seen in adult MIA offspring and has provided evidence that MIA in rats can alter the prominent schizophrenia relevant electrophysiological biomarker of adaptation-independent MMRs, providing a basis to further investigate these measures and their underlying mechanisms.
Cayrol, Romain. "Régulation moléculaire de la barrière hémo-encéphalique." Thèse, 2013. http://hdl.handle.net/1866/10359.
Full textMultiple Sclerosis is an inflammatory demyelinating disease in which immune cells from the peripheral blood infiltrate the central nervous system (CNS) to cause a pathologic neuroinflammatory reaction. Blood borne leucocytes cross the restrictive cerebral endothelium, the blood brain barrier (BBB), to gain access to the CNS parenchyma and cause cellular damage leading to the characteristic demyelinating lesions. The BBB is the interface between the blood and the CNS and as such is a critical mediator of neuro-immune reactions and an important therapeutic target to modulate neuroinflammation. It is essential to have a better understanding of the molecular mechanisms that regulate the BBB properties to elaborate new therapeutic strategies to modulate the BBB and thus the local neuroinflammation reaction. This Ph.D. thesis describes three distinct molecular mechanisms which regulate key BBB properties. The first section describes a novel role for the renin-angiotensin system (RAS) in the neuro-vascular unit (NVU) as a regulator of paracellular permeability. The second part of this thesis characterises the role of a novel adhesion molecule of the BBB, ALCAM. The third part of this work studies the interactions between neural stem cells (NSC) and the BBB and identifies MCP-1 as a critical factor involved in NSC recruitment to the CNS. In the first experimental section we provide evidence that angiotensinogen (AGT) produced and secreted by astrocytes, is cleaved into angiotensin II (AngII) and acts on type 1 angiotensin receptors (AT1) expressed by BBB endothelial cells (ECs). Activation of AT1 restricts the passage of molecular tracers across human BBB-derived ECs through threonine-phosphorylation of the tight junction protein occludin and its mobilization to lipid raft membrane microdomains. We also show that AGT knockout animals have disorganized occludin strands at the level of the BBB and a diffuse accumulation of the endogenous serum protein plasminogen in the CNS, as compared to wild type animals. Finally, we demonstrate a reduction in the number of AGT-immunopositive perivascular astrocytes in multiple sclerosis (MS) lesions, which correlates with a reduced expression of occludin similarly seen in the CNS of AGT knockout animals. Such a reduction in astrocyte-expressed AGT and AngII is dependent, in vitro, on the pro-inflammatory cytokines tumor necrosis factor-α and interferon-γ. Our study defines a novel physiological role for AngII in the CNS and suggests that inflammation-induced downregulation of AngII production by astrocytes is involved in BBB dysfunction in MS lesions. In the second experimental part we focus on adhesion molecules of the BBB. Using a lipid raft-based proteomic approach, we identified ALCAM (Activated leukocyte cell adhesion molecule) as an adhesion molecule involved in leukocyte migration across the BBB. ALCAM expressed on BBB endothelium co-localized with CD6 expressed on leukocytes and with BBB endothelium transmigratory cups. ALCAM expression on BBB cells was up-regulated in active multiple sclerosis and experimental auto-immune encephalomyelitis (EAE) lesions. Moreover, ALCAM blockade restricted transmigration of CD4+ lymphocytes and monocytes across BBB endothelium in vitro and in vivo, and reduced the severity and time of onset of EAE. Our findings point to an important role for ALCAM in leukocyte recruitment into the brain and identify ALCAM as a potential therapeutic target to dampen neuroinflammation. The third experimental part of this thesis studies the interactions between NCS and BBB. NCS represent an attractive source for cell transplantation and neural tissue repair. After systemic injection, NCS are confronted with the specialized BBB endothelial cells before they can enter the brain parenchyma. We investigated the interactions of human fetal neural precursor cells with human brain endothelial cells in an in vitro model using primary cultures. We demonstrated that human fetal neural precursor cells efficiently and specifically migrate to sub-endothelial space of human BBB-endothelium, but not pulmonary artery endothelial cells. When migrated across BBB-endothelial cells, fetal neural precursor cells spontaneously differentiate to neurons, astrocytes and oligodendrocytes. Effective migration and subsequent differentiation was found to be dependant on the chemokine CCL2/MCP-1, but not CXCL8/IL-8. Our findings suggest that an intact blood-brain barrier is not an intrinsic obstacle to neural stem cell migration into the brain and that differentiation of neural precursor cells occur in a sub-endothelial niche, under the influence of the chemokine CCL2/MCP-1. These three experimental sections demonstrate the crucial roles that the BBB plays in regulating the CNS homeostasis. Under pathological conditions, such as during neuro-immune reactions, the BBB is altered and becomes an important local player. The three different molecular mechanisms described in this thesis, contribute to our understanding of the BBB and may allow for the development of novel therapeutic strategies to limit neuroinflammation.