Molecular Regulation of Arterial Thrombosis

描述(由申请人提供)：本项目的总体目标是了解组织因子途径在血管内稳态中的复杂调节作用。动脉血栓形成是血管内皮细胞破裂或损伤导致血管内皮下促凝血剂，包括组织因子(TF)暴露和激活到流动的血液中时开始的。组织因子途径抑制物(TFPI)是组织因子的主要生理抑制物。血管内皮细胞管腔表面局部活性的TFPI在未受干扰的状态下提供了一个非血栓形成表面。TFPI是一种kunitz型丝氨酸蛋白酶抑制剂，通过与因子Vila(通过K1结构域)和因子Xa(通过K2结构域)结合，形成抑制进一步凝血的复合体，从而独特地改变体内的凝血级联反应。然而，如果局部TFPI水平不足以抑制局部TF活性，血栓形成仍将继续。TFPI通过其直接作用和抗凝作用间接影响血管结构。我们的目标是确定内皮细胞在这一过程中的作用。局部活性的TFPI可能来自血管细胞或循环。 内皮细胞在这些过程中可能至少扮演两个角色：作为TFPI作用的场所和作为局部和循环形式的可获得的来源。这些功能在不同的血管床上可能有所不同。最近的临床研究表明，低循环TFPI水平与血管风险增加之间存在关联。本研究的重点是阐明内皮源性TFPI在调节组织因子和TFPI之间的动态平衡中的作用及其对多个血管床中宏观和微观血管结构、功能和血栓形成的影响。我们的基本假设是，血管内皮细胞产生TFPI调节循环和局部TFPI水平，后者调节发育过程中和成人的微血管和大血管功能以及血栓形成。提出了三个具体目标。 具体目的1：确定血管内皮细胞特异性基因缺失对小鼠发育和止血的影响。 具体目的2：明确内皮源性TFPI在血管血栓形成中的作用。 具体目标3：明确内皮源性TFPI在血管重塑包括血管生成中的作用。

DESCRIPTION (provided by applicant): The overall goal of this project is to understand the complex regulatory role of the tissue factor pathway in vascular homeostasis. Arterial thrombosis is initiated when endothelial disruption or injury leads to exposure and activation of subendothelial procoagulants, including tissue factor (TF), to flowing blood. We have focused on tissue factor pathway inhibitor (TFPI) as the major physiologic inhibitor of TF. Locally active TFPI at the luminal surface of endothelium provides a nonthrombogenic surface in the unperturbed state. TFPI, a Kunitz-type serine-protease inhibitor, uniquely modifies the coagulation cascade in vivo by binding to TF-factor Vila (via the K1 domain) and factor Xa (via the K2 domain) forming an inhibitory complex which dampens further coagulation. However, if local levels of TFPI are not adequate to dampen local TF activity, thrombosis continues. TFPI, via proposed direct effects and indirectly via its anticoagulant properties, also influences vascular structure. Our objective is to define the role of the endothelium in this process. Locally active TFPI may be derived from vascular cells or from the circulation. Endothelial cells may play at least two roles in these processes: as a site of TFPI action and as an accessible source of local and circulating forms. These functions may vary in distinct vascular beds. Recent clinical studies indicate an association between low circulating TFPI levels and increased vascular risk. The focus of this proposal is to delineate the role of endothelial-derived TFPI in regulating the homeostatic balance between TF and TFPI and its resultant effects on macro- and micro-vascular structure, function and thrombosis in multiple vascular beds. Our underlying hypothesis is that endothelial production of TFPI regulates circulating and local TFPI levels which modulate micro- and macro-vascular function and thrombosis during development and in adults. Three specific aims are proposed. Specific Aim 1: To determine the effects of endothelial-specific gene deletion of TFPI on murine development and hemostasis. Specific Aim 2: To define the role of endothelial-derived TFPI on vascular thrombosis. Specific Aim 3: To define the role of endothelial-derived TFPI on vascular remodeling including angiogenesis.