CELLULAR PATHOPHYSIOLOGY OF HEPATIC FIBROSIS

纤维化是肝脏对不同损伤的反应。代表 实质“疤痕”，它由胶原蛋白和其他大的细胞外 基质（ECM）蛋白。纤维化的影响是区域性的和局部的， 包括小叶结构和细胞功能的破坏。 纤维化在其先进的形式，肝硬化，是最重要的原因， 肝病的发病率和死亡率。当这个项目开始时，在 1982年，它的目标是定义纤维化的细胞来源，作为一种 这是理解其规则的重要第一步。这是 通过开发大规模隔离和初级 肝脏单个细胞群的培养。脂肪细胞（Ito 或脂肪储存细胞）成为主要的纤维化细胞类型。这是 此外，还发现它经历了被定义为多型反应的激活 炎症。在这种反应中，脂肪细胞从正常的 从静止的类维生素A储存状态转变为ECM产生急剧减少的状态。 出现平滑肌细胞的上调和特征，包括 收缩。在最近的融资期间，我们的重点是 脂肪细胞活化的调节。而可溶性炎症介质 （细胞因子）是部分负责的，如果 任何比单个细胞因子更重要的东西。唯真的求实 ECM的脂细胞活化作用，我们研究了纤维连接蛋白在 细节，发现一个剪接变体，一个包含EIIIA片段， 扮演着关键的角色。这种形式的生产在12年内急剧增加 小时的损伤，并专门定位于窦内皮细胞 细胞在培养物中，含有EIIIA的形式（A+-纤连蛋白）具有直接的 脂肪细胞激活作用，这是完全中和的， EIIIA片段的单克隆抗体。这个的主要目标 继续的建议是通过以下研究来扩展这些观察：（1） 炎症环境对脂肪细胞激活作用的影响 纤连蛋白EIIIA片段：待检查的元素包括其他 纤连蛋白分子中的可变片段， 炎症和ECM环境;（2）EIIIA内的最小结构域， 负责其活性;（3）识别脂肪细胞受体的 （4）抗EIIIA抗体在体内对纤维形成的影响 以EIIIA的活性区为模型的抗体或肽;和 最后（5）A+-纤连蛋白的内皮产生的调节， 可溶性炎症介质，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，基于竞争性抑制EIIIA片段， 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.