TGF-beta, matrix, and myofibroblasts in hepatic fibrosis

描述（由申请人提供）：肝纤维化是对多种原因引起的慢性肝损伤的病理性伤口愈合反应，是肝硬化的前兆，肝硬化是一种在美国和全球范围内导致显著发病率和死亡率的疾病。 纤维化的中心病理生理事件是前体细胞向肌成纤维细胞的分化，平滑肌肌动蛋白表达纤维化细胞负责在受损的肝脏中的大多数异常细胞外基质沉积。 虽然肌成纤维细胞在纤维化中的作用被广泛认识，但导致进行性肌成纤维细胞活化的事件还不清楚。 我们以前已经证明了机械因素的重要性，特别是基质硬度，在肌纤维母细胞分化的两个前体人口，肝星状细胞和门静脉成纤维细胞。 此外，我们和其他人已经证明了可溶性因子的重要性，特别是转化生长因子？(TGF-?),在这个过程中。在这个建议中，我们提出的初步数据表明，基质蛋白的细微变化显着改变了环境的肝，包括机械环境，不同的肌成纤维细胞前体群体（星状细胞与门静脉成纤维细胞）可能会受到不同的影响，这些变化在胆道和非胆道纤维化。 这一提议背后的假设是基质蛋白TGF-β的变化，和力学是相互关联的，并且共同驱动肌成纤维细胞分化和纤维化的发展。该提案的目标是确定三种基质蛋白质-交联胶原蛋白和弹性蛋白，细胞纤连蛋白和富含亮氨酸的小蛋白聚糖-在这些过程中的作用。 这将通过三个具体目标来实现：具体目标#1：确定LOX介导的胶原和弹性蛋白交联在早期纤维化中的作用，特别是LOX和表达的相关同种型的功能性机械后果。 具体目标#2：确定细胞纤连蛋白剪接变异体EIIIA和EIIIB在肌成纤维细胞功能和肝纤维化中的作用，特别是它们在TGF-？活化和胶原纤维形成。 具体目标#3：确定小的富含亮氨酸的蛋白聚糖光蛋白聚糖和纤维调节蛋白在肝肌成纤维细胞分化和纤维化中的作用，特别是它们在介导肝中胶原沉积和机械变化中的作用。 这项工作将提供独特的洞察基质和力学的纤维化介质的作用，并有望阐明肝星状细胞和门静脉成纤维细胞之间的功能差异，以及胆道和非胆道形式的纤维化之间的机制差异。此外，这项工作将确定可行的抗纤维化治疗的新靶点。

DESCRIPTION (provided by applicant): Liver fibrosis is the pathological wound healing response to chronic liver injury from multiple causes and is the precursor to liver cirrhosis, a condition that results in significant morbidity and mortality in the United States and worldwide. The central pathophysiologic event in fibrosis is the differentiation of precursor cells to myofibroblasts, ?-smooth muscle actin-expressing fibrogenic cells responsible for the majority of the abnormal extracellular matrix deposition in the injured liver. Although the role of myofibroblasts in fibrosis is widely appreciated, the events leading to progressive myofibroblast activation are not well understood. We have previously demonstrated the importance of mechanical factors, specifically matrix stiffness, in the myofibroblastic differentiation of tw precursor populations, hepatic stellate cells and portal fibroblasts. Additionally, we an others have demonstrated the importance of soluble factors, particularly transforming growth factor-? (TGF-?), in this process. In this proposal, we present preliminary data suggesting that subtle changes in matrix proteins dramatically alter the environment of te liver, including the mechanical environment, and that different myofibroblast precursor populations (stellate cells versus portal fibroblasts) may be differentially affected by these changes in biliary and non-biliary fibrosis. The hypothesis underlying this proposal is that changes in matrix proteins, TGF-?, and mechanics are interrelated and collectively drive myofibroblast differentiation and the development of fibrosis. The goal of the proposal is to determine the role of three central groups of matrix proteins - cross-linked collagens and elastins, cellular fibronectins, and small leucine-rich proteoglycans - in these processe. This will be achieved through three specific aims: Specific Aim #1: Determine the role of LOX-mediated collagen and elastin cross-linking in early fibrosis, in particular the functional mechanical consequences of the LOXs and the relevant isoforms expressed. Specific Aim #2: Determine the role of the cellular fibronectin splice variants EIIIA and EIIIB in myofibroblast function and liver fibrosis, specifically their role in TGF-? activation and collagen fibrillogeness in vivo and in vitro. Specific Aim #3: Determine the role of the small leucine-rich proteoglycans lumican and fibromodulin in liver myofibroblast differentiation and fibrosis, specifically their roe in mediating collagen deposition and mechanical changes in the liver. This work will provide unique insight into the role of matrix and mechanics as mediators of fibrosis, and is expected to shed light on functional differences between hepatic stellate cells and portal fibroblasts as well as mechanistic differences between biliary and non-biliary forms of fibrosis. Additionally, the work will identify new targets for feasible antifibrotic therapies.