Circulating Tissue Factor: Characterization and Interactions with Factor IX

描述（由申请方提供）：组织因子（TF）是一种整合的膜糖蛋白，在暴露于血液成分后启动凝血级联反应。在经典模型中，TF在上皮细胞和血管外膜细胞中组成型表达，从而在血液周围产生“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，尤其是在炎症刺激后，并且已经假定循环TF的激活对于凝块繁殖是重要的。我们已经使用Tie 2-Cre转基因来切除floxed Tf等位基因以产生其中造血和内皮细胞Tf已经被消除的小鼠（“Tf hem/endo敲除”）。使用这些小鼠的数据表明，内皮和造血Tf是必要的弥散性血管内凝血小鼠模型的内毒素血症。然而，内皮和造血TF在稳态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对止血和血栓形成是否重要？在Tf hem/endo敲除小鼠中，我们将通过Tf mRNA的定量RT-PCR评估循环TF的消融。将使用经过充分验证的方案在小鼠中测试止血和血栓形成。具体目标2。炎症刺激诱导内皮和造血TF促进止血和血栓形成吗？我们将通过暴露于内毒素诱导TF mRNA表达，然后检测出血时间和血栓形成。增强的止血和/或血栓形成将支持内皮和造血TF可能提供炎症和血栓形成之间的联系的假设。具体目标3。缺乏因子IX的小鼠是否可以提供一个致敏系统，在这个系统中我们可以检测到循环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检验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，其在重要的人类炎症性疾病状态中增加，及其与内源性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.