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））暴露于流动的血液中时，体内血栓形成通常是开始的，TF与因子VIIa结合导致因子IX和X的激活，随后纤维蛋白沉积。组织因子途径抑制剂（TFPI）是一种kunitz型丝氨酸蛋白酶抑制剂，通过与tf -因子VIIa催化复合物和因子Xa结合形成一个四元抑制复合物来抑制进一步的凝血，从而独特地改变体内凝血级联反应。我们最近证明，尽管TFPI在动脉粥样硬化斑块中表达，但TF活性占主导地位。因此，我们的工作假设是，动脉粥样硬化斑块中TFPI相对缺乏，TF和TFPI之间的不平衡是血管血栓形成的重要来源，可能有助于斑块的发展和进展。为了进一步界定这种不平衡的重要性，我们提出了两个主要目标。首先，我们将以仅限于血管壁的靶向方式产生过表达TFPI的转基因小鼠，以确定改变有利于TF抑制的局部平衡是否会抑制动脉血栓形成和动脉粥样硬化的发展和进展。其次，为了改变血源性细胞的这种平衡，我们将产生不能从循环血细胞中产生TFPI的小鼠，并在已建立的血栓模型中对这些小鼠进行测试。我们的具体目的是：1)有针对性地产生TFPI过表达的转基因小鼠，2)确定血管中TFPI过表达在动脉粥样硬化发生中的作用，3)确定血管中TFPI表达在小鼠动脉血栓形成模型中的作用，4)确定血源性TFPI表达在小鼠动脉血栓形成模型中的作用。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)深入了解血源性和循环形式的TFPI的相对重要性。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.