ROLE OF TISSUE FACTOR IN HEMOSTASIS & THROMBOSIS

项目总结(见说明)： 组织因子(Tf)是凝血酶活性级联的主要细胞启动子。它在止血方面起着至关重要的作用。然而，在病理条件下，血管内TF的异常表达与血栓形成有关。该提案的目的是确定转铁蛋白在止血和血栓形成中的作用。在目标1中，我们将在小鼠模型中确定单核细胞、内皮细胞和血小板在脂多糖诱导的凝血中的相对贡献。败血症是美国重症监护病房的主要死亡原因。在人类中，先天免疫系统已经进化到通过检测来自病原体的少量产物来感知感染，例如内毒素。然而，对血液中存在的内毒素的过度反应与弥散性血管内凝血(DIG)有关。 在内毒素血症和脓毒症动物模型中，单核细胞和内皮细胞表达转铁蛋白。最近，我们发现内毒素可诱导血小板表达转铁蛋白。在目标2中，我们将使用遗传学和药理学的方法，在体外和体内研究磷脂酰肌醇-3-激酶(PI3K)-蛋白激酶B(Akt)通路在抑制内毒素诱导的基因表达中的作用。 我们已经发现，PI3K-Akt通路抑制了内毒素血症小鼠和单核细胞中Tf和炎症基因的表达。重要的是，在内毒素血症和败血症的动物模型中，几种既能减少凝血又能减少炎症的药物激活了这一途径。在目标3中，我们将研究外源性(Tf和Fvii)和内在(FXII、FXI、FIX和FVIII)凝血通路在组织特异性止血和伤口愈合中的作用。最近的一项研究表明，FVIIa在小鼠体内的高水平表达会导致心肺血栓形成而导致过早死亡。我们将把高FVIIa小鼠与低Tf小鼠或心脏Tf表达增加和降低的小鼠杂交。不同小鼠的表型将检验这一假设，即外部途径介导心脏特异性止血。

PROJECT SUMMARY (See instructions): Tissue factor (TF) is the primary cellular initiator of the coagulation protease cascades. It plays an essential role in hemostasis. Under pathological conditions, however, aberrant TF expression within the vasculature is associated with thrombosis. The goals of this proposal are to determine the roles of TF in hemostasis and thrombosis. In aim 1, we will determine the relative contribution of monocytes, endothelial cells, and platelets to LPS-induced coagulation in a mouse model. Sepsis is the major cause of death in intensive care units in the United States. In humans, the innate immune system has evolved to sense an infection by detecting small amounts of products from the pathogens, such as LPS. However, an excessive response to the presence of LPS in the blood is associated with disseminated intravascular coagulation (DIG). Monocytes and endothelial cells have been shown to express TF in animal models of endotoxemia and sepsis. More recently, we found that LPS induced TF expression in platelets. In aim 2, we will use both genetic and pharmacologic approaches to investigate the role of the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt) pathway in the suppression of LPS-induced gene expression both in vitro and in vivo. We have found that the PI3K-Akt pathway suppresses LPS induction of TF and inflammatory gene expression in monocytic cells and in endotoxemic mice. Importantly, several agents that reduce both coagulation and inflammation in animal models of endotoxemia and sepsis activate this pathway. In aim 3, we will investigate the role of the extrinsic (TF and FVII) and intrinsic (FXII, FXI, FIX and FVIII) coagulation pathways in tissue-specific hemostasis and wound healing. A recent study showed that expression of high levels of FVIIa in mice leads to premature death due to thrombosis in the heart and lung. We will cross high FVIIa mice with either low TF mice or mice with increased and decreased TF expression in the heart. The phenotypes of the different mice will test the hypothesis that the extrinsic pathways mediates heart-specific hemostasis.