MONOCYTE/MACROPHAGE REGULATION OF COAGULATION REACTIONS

单核/巨噬细胞在炎症和动脉粥样硬化中起关键作用 在几种情况下，在血管外组织进行的过程 以纤维增殖性反应和纤维蛋白为特征 证词。由于凝血酶是这些反应的有力效应者，因此 总体假设是单核细胞产生凝血酶 巨噬细胞表面提供重要的生物调节效应分子 在这些地点。目标是定义约束性和动力性 控制导致表达式的分子事件的参数 凝血酶在单核/巨噬细胞表面的表达，并开始阐明 调节促凝血剂表达的细胞机制 表型。 我们的成就包括证明1)因子VIIa必然 单核细胞表达的整合膜蛋白组织因子 膜表面，表现出与因子不同的底物特异性 与重组组织因子结合的VIIa 磷脂小泡，特别是关于不能 识别因子IXa为底物的细胞结合酶；2)类似 单核细胞，来源于人脑微血管的周细胞，可以激活 并通过外部途径传播凝血剂反应(即 组织因子/因子VIIa复合体和凝血酶原酶 复合体)，然而，与单核细胞不同，所需的 酶复合体对激动剂的反应可有差异地调节 刺激和3)单核细胞通过改变因子Va辅因子活性 膜结合型弹性蛋白酶和组织蛋白酶G的表达 与Xa因子亲和力降低的辅因子分子(=3倍)。 我们目前的计划是：1)完成结构/功能分析 弹性蛋白酶和组织蛋白酶裂解Va因子的辅因子活性 G；2)确定组织对因子IX的激活途径 在单核细胞上组装的因子/因子VIIa复合体，以及3)确定 如果组织因子的结构性表达(如观察到的 在我们的周细胞群体中)在因子中调节其辅因子功能 单核细胞诱导的iX活化与组织因子的比较 膜表面。

Monocytes/macrophages play key roles in inflammatory and atherosclerotic processes, which in several instances proceed at extravascular tissue sites and are characterized by a fibroproliferative response and fibrin deposition. Since thrombin is a potent effector of these responses, the overall hypothesis is that thrombin production at the monocyte/ macrophage surface provides an important bioregulatory effector molecule at these sites. The objectives are to define the binding and kinetic parameters governing the molecular events which result in the expression of thrombin at the monocyte/macrophage surface and begin to elucidate the cellular mechanisms which regulate the expression of a procoagulant phenotype. Our accomplishments included demonstrating that 1) factor VIIa bound to the integral membrane protein tissue factor, expressed on the monocyte membrane surface, exhibits different substrate specificity than factor VIIa bound to recombinant tissue factor relipidated with defined phospholipid vesicles, specifically concerning the inability of the cell-bound enzyme to recognize factor IXa as a substrate; 2) like monocytes, pericytes derived from human brain microvessels, can activate and propagate the coagulant response through the extrinsic pathway (i.e. a tissue factor/factor VIIa complex followed by a prothrombinase complex), however, unlike monocytes the activities of the required enzyme complexes can be differentially regulated in response to agonist stimulation and 3) monocytes alter factor Va cofactor activitiy through the expression of membrane-bound elastase and cathepsin G which produce a cofactor molecule with reduced affinity for factor Xa (=3-fold). Our current plans are: 1) to complete the structure/function analyses and cofactor activities of factor Va cleaved by elastase and cathepsin G; 2) to define the activation pathway of factor IX by the tissue factor/factor VIIa complex assembled on monocytes, and 3) to determine if the constitutive expression of tissue factor (such as that observed in our pericyte population) modulates its cofactor function in factor IX activation as compared to tissue factor induced on the monocyte membrane surface.