Academic literature on the topic 'Myofibroblastes portaux'

Dans les maladies chroniques du foie, l’angiogenèse et la fibrose sont étroitement liées. Nosprécédents travaux ont permis de montrer que les myofibroblastes portaux (MFP)contribuaient de façon importante à la fibrogenèse hépatique. L’objectif de ma thèse était dedéterminer si les MFP pouvaient aussi contribuer à l’angiogenèse hépatique. Nous avonsidentifié un nouveau marqueur spécifique des MFP, le collagène XV, grâce auquel nousavons pu mettre en évidence une prolifération des MFP dans des stades avancés de fibrose, àla fois dans des modèles animaux et chez les patients atteints d’hépatopathie chronique. Cetteprolifération des MFP était corrélée à celle des cellules endothéliales. Dans le foie cirrhotiquehumain, les MFP présentaient une distribution périvasculaire, entourant les capillaires àproximité de la réaction ductulaire. L’effet des MFP sur les cellules endothéliales a ensuite étéévalué par des tests d’angiogensèse in vitro et in vivo. Le milieu conditionné des MFPaugmentait la migration et la tubulogenèse des cellules endothéliales et stimulaitl’angiogenèse dans les implants de Matrigel chez la souris. En co-culture, les MFPdeveloppaient des jonctions intercellulaires avec les cellules endothéliales et augmentaient latubulogenèse. Nous avons montré que les MFP secrétaient des microparticules contenant duVEGF-A, capables d’activer VEGFR-2 dans les cellules endothéliales et de médier leur effetpro-angiogénique. Enfin, les cholangiocytes étaient capables d’accroître l’effet proangiogéniquedes MFP. En conclusion, les MFP jouent un rôle clef dans le remodelagevasculaire associé à la fibrose hépatique
Liver angiogenesis and fibrogenesis are closely linked and most of studies have shown thatangiogenesis could worsen fibrosis in chronic liver diseases. Our previous works havedemonstrated that portal myofibroblasts (PMF) greatly contributed to liver fibrogenesis. Theaim of this present work was to determine if PMF could also contribute to liver angiogenesis.We identified collagene XV (col15a1) as a new specific marker for PMF. In vivo, weobserved PMF proliferation (measured by expression of col15a1) at advanced stages offibrosis both in liver from animals models ( CCl4 and BDL) and in livers from patients withchronic liver disease (primary biliary cirrhosis and non alcoolic fatty liver disease). PMFproliferation was correlated with endothelial proliferation. In human cirrhotic liver, PMF werelocated around vessels in fibrotic septa, in proximity to ductular reaction. PMF effects onendothelial cells were assessed in angiogenic tests in vitro and in vivo. PMF conditionedmedium enhanced migration and tubulogenesis of endothelial cells and stimulatedvascularization of matrigel plugs in mice. In coculture, PMF developed junctions withendothelial cells (demosomes and gap junctions) and enhanced endothelial tubulogenesis. Weshowed that PMF secreted VEGFA containing microparticles, able to activate VEGFR-2 inendothelial cells and to mediate their angiogenic function. Cholangiocytes could increasePMF angiogenic properties by stimulating VEGFA expression and microparticles secretion.In conclusion, PMF, studied with a new marker, col15a1, are key cells in hepatic vascularremodeling

La fibrose hépatique est la conséquence de toutes les maladies chroniques du foie et se caractérise par un dépôt excessif de matrice extracellulaire synthétisée par les myofibroblastes. Les myofibroblastes portaux (MFP), l'une des sous populations de myofibroblastes, jouent un rôle majeur dans la progression de la fibrose et sont pro-angiogéniques. Des études ont montré un rôle important du stress du réticulum endoplasmique (RE) dans la fibrose du foie. Nos objectifs étaient de déterminer si un stress du RE survient dans les MFP lors de la fibrose et affecte les fonctions de ces cellules, et d'étudier l'effet du TUDCA, une molécule chaperonne utilisée en clinique dans les maladies biliaires, sur le stress du RE. Le phénotype de MFP activés in vivo, isolés à partir de foie de rats fibreux après cholestase, a été comparé à celui de MFP contrôles que nous avons préalablement bien caractérisés. Nos résultats montrent que les MFP activés in vivo subissent un stress du RE se traduisant par l'activation de la voie PERK. Ce stress du RE n'a pas d'effet sur la différenciation myofibroblastique, diminue les capacités de prolifération et de migration des MFP mais augmente leur pouvoir angiogénique. En revanche, le TUDCA n'a aucun effet sur les paramètres étudiés. Les MFP subissent donc un stress du RE lors de leur activation myofibroblastique qui stimule leur propriété pro-angiogénique et pourrait ainsi favoriser la progression de la fibrose. Cependant le stress du RE inhibe également leurs fonctions de prolifération et de migration ce qui pourrait induire une boucle de contrôle négative limitant leur expansion
Hepatic fibrosis is the consequence of all chronic liver diseases and is characterized by an abnormal extra cellular matrix deposition by myofibroblasts. Portal myofibroblasts (PMF), a subpopulation of hepatic myofibroblasts, play a major role in fibrosis progression and angiogenesis. Accumulating evidences indicate an important role of endoplasmic reticulum (ER) stress in hepatic fibrosis. The aims of this study were to determine whether an ER stress occured in PMF during fibrosis and affected the functions of these cells, and to study the effect of the molecular chaperone TUDCA used in biliary diseases, on ER stress. The phenotype of in vivo activated-PMF obtained from rat fibrotic liver after cholestasis was compared with the phenotype of control PMF that we previously characterized. Our results showed that in vivo activated-PMF underwent ER stress with PERK pathway activation. This ER stress had no effect on myofibroblastic differentiation but reduced PMF proliferation and migration and increased PMF angiogenesis capacity. TUDCA had no effect on these parameters. In conclusion, PMF display ER stress during their activation. ER stress stimulates their pro-angiogenic proprieties and thereby may promote fibrosis progression. However, ER stress also inhibits their proliferation and migration functions, and thereby could provide a negative control loop to restrict their expansion

Mon travail a consisté à comparer les phénotypes de deux types de myofibroblastes hépatiques, les myofibroblastes issus de cellules étoilées du foie (MF-CEFs) et les myofibroblastes portaux (MFPs). Pour cela, nous avons utilisé deux approches complémentaires, la protéomique et la transcriptomique, qui nous ont permis de déterminer des caractéristiques phénotypiques et fonctionnelles spécifiques de chaque population de myofibroblastes. Nous avons mis en évidence que, si les MF-CEFs semblent plus fortement impliqués dans la régénération hépatique, l’angiogenèse et la régulation du tonus vasculaire, ils expriment également beaucoup de protéines associées au stress. Les MFPs présenteraient un phénotype contractile plus différencié et semblent très impliqués dans le recrutement des leucocytes. D’autre part, l’utilisation de marqueurs identifiés dans ce travail a confirmé, dans un modèle de cirrhose, que les MFPs sont localisés dans les espaces portes et les septa. Enfin, l’étude par microarray a permis d’identifier un transcrit dont la protéine, l’ostéoprotégérine, est synthétisée par les MF-CEFs ; cette protéine peut être dosée dans le sérum et en particulier, elle est augmentée chez les patients fibrotiques. Incluse dans un nouveau score de fibrose, sa performance diagnostique pour l’évaluation du stade fibrose chez les patients atteints d’hépatite C chronique semble supérieure à celle des scores existants. Ce travail apporte donc des éléments nouveaux pour la compréhension des rôles respectifs des MF-CEFs et MFPs dans la fibrose hépatique, en suggèrant notamment une contribution importante des MFPs, et ouvre également des perspectives cliniques intéressantes.

Les travaux antérieurs ont montré que les myofibroblastes portaux (PMFs) contribuaient de manière significative à la fibrogenèse et à l'angiogénèse dans la fibrose hépatique. L'objectif principal de cette thèse était de cartographier les cellules mésenchymateuses portales, et plus particulièrement la niche des cellules souches mésenchymateuses portales. Nous avons caractérisé la variété des cellules mésenchymateuses portales du foie de souris. Résultat important, nous avons identifié une population de cellules mésenchymateuses portales ayant les caractéristiques de cellules souches mésenchymateuses, désignées cellules souches mésenchymateuses portales (PMSCs), qui ont la capacité de se transformer en PMFs in vitro. Nous avons identifié Slit2 comme un marqueur des PMSCs par scRNA-seq et bulk RNA-seq. In vivo, nous avons mis en évidence l'expansion de PMSCs dans le foie de modèles murins de fibrose hépatique et de patients ayant une maladie chronique du foie. Nous avons identifié des signatures transcriptomiques spécifiques des PMSCs d’une part et des cellules étoilées du foie (CEF), de l’autre. Les résultats obtenus par l’utilisation de ces marqueurs, renforcent nos conclusions selon lesquelles les PMSCs s’accumulent de façon corrélée avec la fibrogenèse et l'angiogenèse, tandis que la signature des CEFs ne varie pas. En conclusion, nos travaux apportent des éléments à la connaissance des populations de cellules mésenchymateuses portales du foie. Ils ont permis d’identifier et caractériser les PMSCs ainsi que les myofibroblastes qui en dérivent, ouvrant de nouvelles perspectives dans le domaine des thérapies ciblées et des biomarqueurs pour la pratique clinique
Previous work has demonstrated that portal myofibroblasts (PMFs) significantly contributed to liver fibrogenesis and modulated angiogenesis in liver fibrosis. The main aim of this thesis was to elucidate the landscape of portal mesenchymal cells, with a particular focus on a portal mesenchymal stem cell niche. We characterized the murine normal liver portal mesenchymal cell landscape. Importantly, we revealed a portal mesenchymal cell population with the features of mesenchymal stem cells (MSCs), designated portal mesenchymal stem cells (PMSCs) that possessed the ability to give rise to PMFs in vitro. Furthermore, we identified Slit2 as a new marker of PMSCs based on scRNA-seq and bulk RNA-seq analysis. In vivo, we observed PMSC expansion (measured by the expression of Slit2) in liver from both animal fibrosis models (DDC and CDAA) and patients with chronic liver disease (NASH, PSC and other liver disease). Notably, we defined the specific gene signatures for PMSCs and hepatic stellate cells (HSCs), respectively. By using these markers, we provide further evidence indicating that PMSCs expand in correlation with fibrogenesis and angiogenesis in different murine and human liver diseases, whereas the HSCs gene signatures did not vary. In conclusion, our work collectively offers insights into the components and functions of the mammalian liver portal mesenchymal cell populations, and in particular, identify and characterize PMSCs and their derived myofibroblasts, opening up the possibility for the development of novel targeted drugs or biomarkers of clinical significance with increased precision

Ventral body wall closure (VBW) defects are amongst the most common human congenital anomalies. They represent a wide and heterogeneous group of phenotypic defects that can present in isolation or as a component in a larger syndromic anomaly. In addition, the incidence of associated anomalies is high and reaches 75% of fetuses in some types of VBW closure defects. Nevertheless, the embryonic origin and the underlying cellular and molecular mechanisms between ventral closure defects and their associated congenital anomalies remain poorly characterised. This is in part due to the poor understanding of the physiological mechanisms that regulate the development of ventral organs and the lack of representative transgenic animal models allowing detailed in vivo analysis of defect formation. Transforming growth factor beta (TGF-ÃŽÂ2) signalling is essential for VBW closure and vascular and cardiac development. Yet, its mechanism of action and the responding cell(s) in the body wall remain largely unknown. In addition, in various cells TGF-B can induce the expression of Tagln, encoding for a cytoskeleton associated protein that enhances cell migration. No function has been ascribed to TAGLN in body wall development. I define here a role of TGF-B during a critical time window in embryonic development to fashion the ventral body wall, anterior diaphragm and parts of the circulatory system. I identify a population of TAGLN+ myofibroblasts that respond to a temporally regulated TGF-B signalling originating from the epithelium of the primary body wall. Deletion of TGF-B receptor in TAGLN+ cells leads to failure of ventral body wall closure, anterior diaphragmatic hernia, cardiac and outflow tract anomaly. Nevertheless, the descending aorta and the large aortic branches are spared. By using advanced transgenic methodology, I generated novel transgenic mouse lines that enabled me to fate map the cells that initiate the formation of important mesenchymal tissues. These studies revealed that the origin of aortic vascular smooth muscle cells can be traced back to a group of progenitor cells that reside in the wall of the dorsal aorta before the VBW closure. My studies provide intriguing evidence for spatially restricted role for TGF-B signalling in ascending but not descending aorta morphogenesis. I used a variety of techniques to characterise, analyse and quantify important mechanisms during mesenchymal and vascular development, their response to injury and repair. This thesis has been written in an alternative format, comprising the different areas which have been investigated. Collectively, the results presented here provide new insights into the role of migratory and mechanically stabilising cells in the development and maintenance of critical structures in the body and their common role in the development of concurrent congenital anomalies. A detailed understanding of the molecular signalling pathways and cells that drive VBW closure raises the hope that the related birth defects can in the future be treated by precise gene and cell therapies.

Introduction: Dupuytren's disease (DD) is an ill-defined fibroproliferative disorder affecting the palms of the hands of certain patient groups. Whether changes in DD fibroblasts are due to genetic alterations alone or related to metabolic dysregulation has not yet been investigated. Hypotheses: 1. DD is a disease of several networks rather than of a single gene. 2. DD may be investigated more effectively by employing systems biology. 3. Strict definition of cell passage number is important for the revelation of any DD phenotype. 4. Some of the differences between DD and healthy tissues reside in a difference in their respiratory metabolism. 5. Any such differences are akin the Warburg effect noted for tumour cells in the literature. Methods: We induced hypoxia in healthy and disease cells to test whether the difference in disease cell types and healthy is the same as the difference in control fibroblasts cultured in normoxia and hypoxia. We investigated both at the metabolic level (intracellular and extracellular) and at the transcript level. This study also employed Fourier transform infrared spectroscopy to permit profiling of cells: (1) DD cords and nodules against the unaffected transverse palmar fascia (internal control), (2) those (1) with carpal ligamentous fascia (external controls) (3) those in (1) against DD fat surrounding the nodule, and skin overlying the nodule. We then compared metabolic profiles of the above to determine the effect of serial passaging by assessment of reproducibility. Subsequently, a novel protocol was employed in carefully controlled culture conditions for the parallel extraction of the metabolome and transcriptome of DD-derived fibroblasts and control at normoxic and hypoxic conditions to investigate this hypothesis. Gas chromatography-mass spectrometry combined with microarrays was employed to identify metabolites and transcript characteristic for DD tissue phenotypes. The extracellular metabolome was also studied for a selected subset. The metabolic and transcriptional changes were then integrated employing a network approach. Results: Carefully controlled culture conditions combined with multivariate statistical analyses demonstrated metabolic differences in DD and unaffected transverse palmar fascia, in addition to the external control. Differences between profiles of the four DD tissue phenotypes were also demonstrated. In addition early passage (0-3) metabolic differences were observed where a clear separation pattern in clusters was observed. Subsequent passages (4-6) displayed asynchrony, losing distinction between diseased and non-diseased sample phenotypes. A substantial number of dysregulated metabolites involved in amino acid metabolism, carbohydrate metabolism and also metabolism of cofactors and vitamins including downregulated cysteine and aspartic acid have been identified from the integrative analyses. Metabolic and transcriptional differences were revealed between fibroblast cell samples (passage number 3) cultured in 1% and 21% oxygen. The hypothesis that the difference in disease and healthy cells maybe akin to the differences in healthy cells in normoxia and hypoxia was rejected as only a very small number of significant molecules from these studies coincided in perturbed fascia and disease samples. No lactic acid was observed and little difference in the pyruvate concentrations. Yet, upon perturbation several of these transcripts and metabolites involved in the afore-mentioned pathways were significantly dysregulated. Conclusion: Early, but not late, passage numbers of primary cells provide representative metabolic and transcript fingerprinting for investigating DD. A unique parallel analysis of transcript and metabolic profiles of DD fibroblasts and control, enabled a robust characterization of DD and correlation of parameters across the various levels of systemic description. The tools that should facilitate our understanding of these complex systems are immature, but the pleiotropy of the difference between healthy and DD tissue suggest the aetiology of a network-based disease.

Chronic liver disease is responsible for most of the clinical burden of liver disease. Chronic liver injury can occur via a variety of mechanisms, including sterile inflammation and activation of innate and adaptive immunity. Despite the diversity of disease aetiologies and the ability of the liver to regenerate, a significant minority of patients with chronic liver disease proceed to liver fibrosis and eventually cirrhosis, which is defined histologically by regenerative hepatocyte nodules surrounded by fibrous bands of matrix. Ongoing liver injury stimulates the development of a myofibroblast cell type which is responsible for matrix remodelling, haemodynamic changes, and immune cell regulation. This typically results in repair without significant modification of the basic liver structure. In a few subjects, this repair process results in alterations of the basic structure of the liver with loss of hepatocyte mass, deposition of collagen, and the development of hypertension in the portal venous system. Although cirrhosis is well defined histologically, there is a spectrum of severity. In early cirrhosis, patients are asymptomatic but with increasing derangement in hepatic function and portal hypertension, patients can decompensate and develop ascites, coagulopathy, encephalopathy, jaundice, renal failure, oesophageal varices, and spontaneous bacterial infections. Management is focused on removing or reducing ongoing liver injury, and managing cirrhosis-related complications by the use of low-salt diets, diuretics, β‎-blockers, endoscopic therapy, vasopressors, and antibiotics. There is, as yet, no definite role for antifibrotic medications.