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稳态中的复杂调节作用。当内皮破坏或损伤导致内皮下促凝剂（包括组织因子（TF））暴露于流动血液并活化时，动脉血栓形成开始。组织因子途径抑制物（TFPI）是TF的主要生理抑制剂。在未受干扰状态下，内皮管腔表面的局部活性TFPI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TF-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抑制性复合物，独特地改变体内凝血级联反应。然而，如果局部TFPI水平不足以抑制局部TF活性，则血栓形成继续。TFPI，通过提出的直接作用和间接通过其抗凝特性，也影响血管结构。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可以来源于血管细胞或循环。 内皮细胞在这些过程中至少扮演两个角色：作为TFPI作用的位点和作为局部和循环形式的可访问来源。这些功能在不同的血管床中可能不同。最近的临床研究表明，低循环TFPI水平和血管风险增加之间的关联。该建议的重点是描述内皮源性TFPI在调节TF和TFPI之间的稳态平衡中的作用及其对多个血管床中的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，内皮生产TFPI调节循环和局部TFPI水平，调节微血管和大血管功能和血栓形成过程中的发展和成人。提出了三个具体目标。 具体目的1：确定TFPI的内皮特异性基因缺失对小鼠发育和止血的影响。 具体目标2：明确内皮源性TFPI在血管血栓形成中的作用。 具体目标3：确定内皮源性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.