FIBRINOGEN, INFLAMMATION, AND ATHEROGENESIS

动脉粥样硬化越来越被认为是一种慢性炎症 过程 凝血因子纤维蛋白原（FGN）提供了一个关键的 在细胞可以迁移的损伤部位的临时基质， 执行涉及止血的专门功能， 炎症 流行病学，组织学和实验线 有证据表明FGN可能计划致病作用， 动脉粥样硬化 虽然血浆FGN水平升高与 心血管疾病的风险增加，目前尚不清楚是否 RGN是一种替代标记物或直接参与动脉粥样硬化形成。 尽管FGN在健康和疾病中的重要性， 和主要FGN分解代谢途径的位点未知。 初步数据表明，整合素Mac-1（CD 11b/CD 18） 和肝细胞上的avb 3（CD 51/CD 61）可以结合， 内化并通过溶酶体组织蛋白酶D降解FGN。 数据 自上次提交以来获得的数据在家兔模型中提供了证据 FGN与Mac-1直接相互作用 影响血管修复。 这一建议的主要假设是 整合素是FGN水平的主要决定因素，它们的功能 在这方面是由促炎细胞因子调节的， 尿激酶受体（μ mPAR）和血浆调节 FGN水平的高低将直接影响动脉粥样硬化的发展。 本文提出了三个具体目标：（1）研究其作用机理 和调节整合素介导的FGN周转;我们建议， 定义对相互作用重要的结构决定因素， FGN及其整合素受体，并探讨细胞因子的作用 FGN的降解。 微米PAR似乎是一个重要的 整合素的调节剂。 连接整合素的分子通路 将在真核细胞中解剖微米PAR的功能 用MAC-1和avb 3的野生型和突变形式转染;（2） 以确定FGN催化剂的体内机制。 血浆清除率 将进行实验以确定FGN的动力学 在野生型中的代谢，受体（MAC-1和微米PAR）- 缺陷型;和组织蛋白酶D缺陷型小鼠。 离体灌注 将使用大鼠肝脏制备物来研究 FGN代谢中的细胞因子，并鉴定细胞类型 （3）研究FGN的作用 缺乏对转基因小鼠动脉粥样硬化发展的影响 过量表达人apoB。 纯合子FGN缺陷小鼠将 与表达人apoB的小鼠交配， 表达apoB转基因并且是纯合的 或FGN缺陷杂合子。 饮食诱导的动脉粥样硬化 病变面积将随时间定量，以确定FGN是否 缺乏在动脉粥样硬化形成的鼠模型中提供保护。 总的来说，这些实验旨在阐明FGN是否 在动脉粥样硬化的病因学中起作用，如果是这样， 针对FGN调节的药物设计的分子基础 程度.

Atherosclerosis is increasingly regarded as a chronic inflammatory process. The coagulation factor fibrinogen (FGN) provides a critical provisional matrix at sites of injury in which cells can migrate and carry out the specialized functions involved in hemostasis and inflammation. Epidemiologic, histologic, and experimental lines of evidence indicate the FGN may plan pathogenic roles in atherosclerosis. While elevated plasma FGN levels are associated with an increased risk of cardiovascular disease, it remains unclear whether RGN is a surrogate marker or directly participates in atherogenesis. Despite the importance of FGN in health and disease, the mechanism and site of the major FGN catabolic pathway(s) are unknown. Preliminary data demonstrate that the integrins Mac-1 (CD11b/CD18) on monocytes and avb3 (CD51/CD61) on hepatocytes can bind, internalize, and degrade FGN via lysosomal cathepsin D. Data obtained since the prior submission provide evidence in a rabbit model of vascular injury that interactions between FGN and Mac-1 directly influence vascular repair. The central hypotheses of this proposal are that integrins are a major determinant of FGN level, that their function in this regard is regulated by pro-inflammatory cytokines and the urokinase receptor (microns PAR), and that modulation of plasma FGN level will directly affect the development of atherosclerosis. Three specific aims are proposed: (1) to investigate the mechanism and regulation of integrin-mediated FGN turnover; we proposed to define the structural determinants important to the interaction between FGN and its integrin receptors and investigate the effect of cytokines on FGN degradation. Microns PAR appears to be an important regulator of integrins. The molecular pathways which connect integrin function with that of microns PAR will be dissected in eukaryotic cells transfected with wild-type and mutant forms of MAC-1 and avb3; (2) to define the in vivo mechanism of FGN catabolism. Plasma clearance experiments will be performed to determine the kinetics of FGN metabolism in wild-type, receptor (MAC-1 and microns PAR)- deficient; and cathepsin D minus deficient mice. An isolated perfused rat liver preparation will be utilized to investigate the effects of cytokines in FGN metabolism and to identify the cell type(s) responsible for FGN catabolism; and (3) to study the effect of FGN deficiency on the development of atherosclerosis in transgenic mice over-expressing human apoB. Homozygous FGN-deficient mice will be bred with mice expressing human apoB to generate double transgenics that express the apoB transgene and are either homozygous or heterozygous for FGN deficiency. Diet-induced atherosclerotic lesion area will be quantified over time to determine whether FGN deficiency affords protection in a murine model of atherogenesis. Collectively, these experiments are designed to clarify whether FGN has an etiologic role in atherosclerosis and, if so, provide a potential molecular basis for drug design aimed at the modulation of FGN levels.