MOLECULAR REGULATION OF ARTERIAL THROMBOSIS

动脉血栓形成是动脉粥样硬化的主要并发症，是西方世界的主要死亡原因。 当腔内破坏导致内皮下促凝剂如组织因子（TF）暴露于流动的血液时，体内血栓形成通常开始，TF与因子VIIa结合导致因子IX和X的活化以及随后的纤维蛋白沉积。组织因子途径抑制剂（TFPI）是一种Kunitz型丝氨酸蛋白酶抑制剂，通过在两步过程中与TF-因子VIIa催化复合物和因子Xa结合形成抑制进一步凝血的四元抑制复合物，独特地改变体内凝血级联反应。我们最近证实，尽管在动脉粥样硬化斑块中TFPI表达，TF活性占主导地位。因此，我们的工作假设是，有一个相对不足的TFPI在动脉粥样硬化斑块和TF和TFPI之间的不平衡是血管血栓形成的重要来源，并可能有助于斑块的发展和进展。为了进一步确定这种不平衡的重要性，我们提出两个主要目标。首先，我们将产生转基因小鼠，过度表达TFPI在一个有针对性的方式限制到血管壁，以确定是否改变有利于TF抑制局部平衡将抑制动脉血栓形成和动脉粥样硬化的发展和进展。第二，为了改变血液来源的细胞中的这种平衡，我们将产生不能从循环血细胞产生TFPI的小鼠，并在已建立的血栓形成模型中测试这些小鼠。我们的具体目标是：1）产生以靶向方式过表达TFPI的转基因小鼠，2）确定血管TFPI过表达在动脉粥样硬化发展中的作用，3）确定血管TFPI表达在动脉血栓形成的鼠模型中的作用和4）确定血液来源的TFPI表达在动脉血栓形成的鼠模型中的作用。我们预计这些研究将：1）阐明TF和TFPI之间的平衡调节动脉粥样硬化和血栓形成的新机制，2）提供对血液来源和循环形式的TFPI的相对重要性的见解。最终，这些见解将导致新的治疗方法，以预防和治疗动脉粥样硬化及其最重要的并发症，血栓形成。

Arterial thrombosis, a major complication of atherosclerosis, is the leading cause of death in the Western world. Thrombosis in vivo is usually initiated when endoluminal disruption leads to exposure of subendothelial procoagulants such as tissue factor (TF) to flowing blood, with binding of TF to factor VIIa resulting in activation of factors IX and X and subsequent fibrin deposition. Tissue factor pathway inhibitor (TFPI), a Kunitz-type serine-protease inhibitor, uniquely modifies the coagulation cascade in vivo by binding in a two-step process to TF-factor VIIa catalytic complex and factor Xa forming a quaternary inhibitory complex which dampens further coagulation. We have recently demonstrated that in spite of TFPI expression in atherosclerotic plaque, TF activity predominates. Thus our working hypothesis is that there is a relative deficiency of TFPI in atherosclerotic plaque and that the imbalance between TF and TFPI is an important source of vascular thrombogenicity and may contribute to plaque development and progression. To further define the importance of this imbalance, we propose two major goals. First, we will generate genetically modified mice that overexpress TFPI in a targeted manner limited to the vessel wall to determine whether altering the local balance favoring TF inhibition will inhibit arterial thrombosis and the development and progression of atherosclerosis. Second, to alter this balance in blood- derived cells, we will generate mice incapable of producing TFPI from circulating blood cells and test these mice in an established model of thrombosis. Our Specific Aims are: 1) To generate transgenic mice which overexpress TFPI in a targeted manner, 2) To determine the role of vascular TFPI overexpression in the development of atherosclerosis, 3) To determine the role of vascular TFPI expression in a murine model of arterial thrombosis and 4) To determine the role of blood-derived TFPI expression in a murine model of arterial thrombosis. We anticipate that these studies will; 1) elucidate new mechanisms by which the balance between TF and TFPI regulates the development of atherosclerosis and thrombosis and 2) provide insights into the relative importance of blood-derived and circulating forms of TFPI. Ultimately these insights will lead to new therapeutic approaches to prevent and treat atherosclerosis and its most important complication, thrombosis.