Circulating Tissue Factor: Characterization and Interactions with Factor IX

描述（由申请人提供）：组织因子（TF）是一种完整的膜糖蛋白，在暴露于血液成分后启动凝血级联。在经典模型中，TF在上皮细胞和血管外表皮细胞中组成性表达，从而在血液周围形成“止血包膜”，但与血液分离。然而，内皮细胞和造血细胞可以表达TF，特别是在炎症刺激后，并且已经假设循环TF的激活对凝块的增殖很重要。我们使用了一个Tie2-Cre转基因去除了一个固定的Tf等位基因，从而产生了造血和内皮细胞Tf被切除的小鼠（“Tf hem/endo敲除”）。使用这些小鼠的数据表明，内皮和造血Tf对于内毒素血症小鼠模型的弥散性血管内凝血是必要的。然而，内皮和造血TF在体内平衡和炎症状态中的正常作用尚不清楚。我们应该问：具体目标1。内皮和造血TF对止血和血栓形成重要吗？在Tf hem/endo敲除小鼠中，我们将通过定量RT- PCR检测Tf mRNA来评估循环Tf的消融情况。止血和血栓形成将在小鼠中使用经过验证的方案进行测试。具体目标2。炎症刺激诱导内皮和造血TF是否促进止血和血栓形成？我们将通过暴露于内毒素诱导TF mRNA表达，然后检查出血次数和血栓形成。增强的止血和/或血栓形成将支持内皮和造血TF可能在炎症和血栓形成之间提供联系的假设。具体目标3。缺乏IX因子的小鼠是否提供了一个敏化系统，我们可以在其中检测循环TF的正常作用？我们将通过检查缺乏循环TF和因子IX的小鼠的止血和血栓形成来验证这些系统部分冗余的假设。我们的研究旨在确定循环TF的作用，它在重要的人类炎症疾病状态下增加，以及它与内在凝血途径的相互作用。这些研究可能为治疗这些炎症状态提供有吸引力的治疗靶点。

DESCRIPTION (provided by applicant): Tissue factor (TF) is an integral membrane glycoprotein that initiates the coagulation cascade after exposure to blood components. In classical models, TF is constitutively expressed in epithelia and vascular adventitial cells so as to create a "hemostatic envelope" around but separated from blood. However, endothelial cells and hematopoietic cells can express TF especially after inflammatory stimuli, and it has been postulated that activation of circulating TF is important for clot propagation. We have used a Tie2-Cre transgene to excise a floxed Tf allele to generate mice in which hematopoietic and endothelial cell Tf has been ablated ('Tf hem/endo knockout"). Data using such mice suggest that endothelial and hematopoietic Tf is necessary for disseminated intravascular coagulation in mouse models of endotoxemia. However, the normal role of endothelial and hematopoietic TF in homeostasis and in inflammatory states is unknown. We shallask: Specific Aim 1. Is endothelial and hematopoietic TF important for hemostasis and thrombosis? In Tf hem/endo knockout mice, we will assess ablation of circulating TF by quantitative RT- PCR for Tf mRNA. Hemostasis and thrombosis will be tested in mice using well-validated protocols. Specific Aim 2. Does induction of endothelial and hematopoietic TF by inflammatory stimuli promote hemostasis and thrombosis? We will induce TF mRNA expression via exposure to endotoxin and then examine bleeding times and thrombosis. Enhanced hemostasis and/or thrombosis would support the hypothesis that endothelial and hematopoietic TF may provide a link between inflammation and thrombosis. Specific Aim 3. Might mice lacking factor IX provide a sensitized system in which we might detect normal roles for circulating TF? We will test the hypothesis that these systems are partially redundant by examining hemostasis and thrombosis in mice that lack both circulating TF and factor IX. Our study seeks to define the role of circulating TF, which is increased in important human inflammatory disease states, and its interaction with the intrinsic coagulation pathway. These studies may provide attractive therapeutic targets for treatment of these inflammatory states.