CELLULAR PATHOPHYSIOLOGY OF HEPATIC FIBROSIS

纤维化是肝脏对各种损伤的反应。代表 实质上的“疤痕”，它由胶原蛋白和其他大的细胞外物质组成 基质(ECM)蛋白。纤维化的影响既是地区性的，也是局部的， 涉及小叶结构和细胞功能的破坏。 其晚期形式的纤维化，即肝硬变，是 肝病的发病率和死亡率。当这个项目开始时，在 1982年，它的目标是将纤维化的细胞来源(S)定义为 这是理解其监管的重要第一步。这是 通过开发大规模隔离和初级隔离的方法来实现 肝脏单个细胞群体的培养。脂肪细胞(伊藤 或储存脂肪的细胞)成为主要的纤维化细胞类型。确实是 此外，发现经历激活，被定义为多型性反应 致炎。在这种反应中，脂肪细胞从正常的 静止的维甲酸储存状态到细胞外基质产生急剧增加的状态 上调，并出现平滑肌细胞的特征，包括 收缩。在最近的资助期内，我们的重点是 调节脂肪细胞的激活。而可溶性炎症介质 (细胞因子)部分负责，如果BCM本身的作用是 任何事情，都比单个细胞因子更重要。在追求 细胞外基质对脂肪细胞的激活作用，我们研究了纤维连接蛋白对脂肪细胞的激活作用 细节，发现一个剪接变体，一个包含EIIIA片段的， 起着至关重要的作用。这种形式的产量在12年内急剧增加 损伤数小时，并定位于肝窦内皮细胞 细胞。在培养中，含有EIIIA的形式(A+-纤维连接蛋白)有直接的 脂肪细胞的激活作用，可被一种 抗EIIIA片段的单抗。-这项工作的主要目标 继续的建议是通过以下研究来扩展这些观察：(1) 炎症环境对小鼠脂肪细胞活化作用的影响 纤维连接蛋白EIIIA片段：需要检查的成分包括其他 纤维连接蛋白分子中的可变节段，可溶性的介体 炎症和ECM上下文；(2)EIIIA中的最小结构域 负责其活性；(3)识别的脂肪细胞受体 EIIIA片段；(4)抗EIIIA对体内肝纤维化的影响 模拟EIIIA活性区域的抗体或多肽；以及 最后(5)血管内皮细胞A+-纤维连接蛋白生成的调节 炎症的可溶性介质，特别是转化生长因子- B.这项工作的高潮将是一种新的治疗方法 纤维化，基于对其EIIIA片段的竞争性抑制 脂肪细胞受体。

Fibrosis is the liver's response to diverse injuries. Representing parenchymal "scar", it consists of collagens and other large extracellular matrix (ECM) proteins. The effects of fibrosis are both regional and local, involving disruption of lobular structure and also cellular function. Fibrosis in its advanced form, cirrhosis, is the most important cause of morbidity and mortality from liver disease. When this project began, in 1982, its goal was defining the cellular source(s) of fibrosis, as an essential first step towards understanding its regulation. This was accomplished through development of methods for mass isolation and primary culture of the individual cell populations of the liver. The lipocyte (Ito or fat-storing cell) emerged as the principal fibrogenic cell type. It was found, moreover, to undergo activation, defined as a pleiotypic response to inflammation. In this response, lipocytes convert from a normally quiescent, retinoid-storing state to one in which ECM production is sharply upregulated and features of smooth-muscle cells appear, including contraction. During the recent period of funding, our focus has been the regulation of lipocyte activation. While soluble mediators of inflammation (cytokines) are in part responsible, the role of the BCM itself is, if anything, more important than that of individual cytokines. In pursuing the lipocyte-activating effect of ECM, we have investigated fibronectin in detail, finding that a splice variant, one containing the EIIIA segment, plays a critical role. Production of this form increases sharply within 12 hours of an injury and is localized specifically to sinusoidal endothelial cells. In culture the EIIIA-containing form (A+-fibronectin) has direct lipocyte-activating effects, which are completely neutralized by a monoclonal antibody to the EIIIA segment. The-major goal of this continuation proposal is to extend these observations with studies of: (1) the impact of the inflammatory milieu on the lipocyte activating effect of the fibronectin EIIIA segment: elements to be examined include other variable segments in the -fibronectin molecule, soluble mediators of inflammation and the ECM context; (2) the minimum domain within EIIIA that is responsible for its activity; (3) the lipocyte receptor that recognizes the EIIIA segment; (4) the effect on fibrogenesis in vivo of anti-EIIIA antibodies or of peptides modeled on the active region of EIIIA; and finally (5) the regulation of endothelial production of A+-fibronectin by soluble mediators of inflammation, particularly transforming growth factor- B. The culmination of this work will be a new approach to therapy for fibrosis, based on competitive inhibition of the EIIIA segment for its lipocyte receptor.