ROLE OF TISSUE FACTOR IN HEMOSTASIS & THROMBOSIS

项目总结（见说明）： 组织因子（TF）是凝血蛋白酶级联反应的主要细胞起始因子。它在止血中起着至关重要的作用。然而，在病理条件下，血管系统内异常的TF表达与血栓形成有关。本提案的目的是确定TF在止血和血栓形成中的作用。在目标1中，我们将确定单核细胞、内皮细胞和血小板对小鼠模型中LPS诱导的凝血的相对贡献。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（例如LPS）来感测感染。然而，对血液中存在的LPS的过度反应与弥散性血管内凝血（DIG）相关。 在内毒素血症和脓毒症的动物模型中，单核细胞和内皮细胞已显示表达TF。最近，我们发现LPS诱导血小板TF表达。在目标2中，我们将使用遗传学和药理学的方法来研究磷脂酰肌醇-3-激酶（PI 3 K）-蛋白激酶B（Akt）途径在体外和体内抑制LPS诱导的基因表达中的作用。 我们已经发现PI 3 K-Akt通路抑制LPS诱导的TF和单核细胞和内毒素血症小鼠中的炎症基因表达。重要的是，在内毒素血症和脓毒症的动物模型中减少凝血和炎症的几种药物激活了该途径。在目标3中，我们将研究外源性（TF和FVII）和内源性（FXII、FXI、FIX和FVIII）凝血途径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，小鼠中高水平的FVIIa表达导致由于心脏和肺中的血栓形成而过早死亡。我们将高FVIIa小鼠与低TF小鼠或心脏中TF表达增加和减少的小鼠杂交。不同小鼠的表型将检验外源性途径介导心脏特异性止血的假设。

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.