Smooth Muscle Cell Tissue Factor and Cardiovascular Disease

描述（由申请人提供）：组织因子（TF）是凝血级联的起始物，在止血和血栓形成中起关键作用。血管中有许多TF来源，包括巨噬细胞、内皮细胞和平滑肌细胞（SMC）。此外，TF在促凝微粒（MPs）上循环。可能不同来源的TF对TF介导的每个病理过程都是至关重要的。本提案的重点是smc衍生的TF。在SMC中，TF作为对生长因子和细胞因子的主要反应而受到调节，在动脉SMC中，TF在损伤反应中上调。在多种动物模型中，TF被认为是SMC迁移的中介，其抑制作用可减少损伤后的内膜增生。TF在动脉粥样硬化斑块的介质和内膜中含量丰富，smc来源的TF被认为是导致富含脂质的坏死核心中TF负担加重的原因。因此，TF可能在斑块进展中起作用，并可能介导与斑块破裂相关的血栓形成。我们最近开发了一种小鼠TF/Sm221Cre，其smc来源的TF缺乏约95%。小鼠发育正常，无明显的止血异常，但FeCl3损伤引起的动脉血栓形成明显减少。这些小鼠的SMC在因子(F) VIIa的作用下无法迁移。我们的初步数据表明，这只小鼠对钢丝损伤的反应减少了内膜增生，并且令人惊讶的是，血管紧张素II （Ang II）反应产生了更严重的动脉瘤。我们假设SMC衍生的TF可能在介导心血管病理中发挥多种作用，包括对SMC生理的直接影响，通过生成凝血酶的间接影响，以及作为促凝血活性的来源。TF/Sm221Cre小鼠使我们能够探索SMC衍生的TF的不同作用，并确定SMC衍生的TF与循环TF在各种病理状态下的相对贡献。目的1将确定抑制smc来源的TF导致内膜增生减少的机制，并利用全球TF减少99%的小鼠骨髓移植和TF的药物抑制来探索smc来源的TF和血液TF对这一过程的相对贡献。本研究还将深入研究体外培养SMC中的FVIIa信号，并确定tf介导的SMC迁移的细胞机制。目的2将确定smc来源的TF在介导腹主动脉瘤（AAA）中的作用。为了方便这些实验，TF/Sm221Cre小鼠将被培育成LDLR-/-背景。目的3将利用这只小鼠来确定smc来源的TF在介导动脉粥样硬化发生和进展中的作用。目的4将验证不同类型的血栓形成（大血管与微血管、静脉与动脉）涉及不同机制的假设，并将进一步确定smc衍生的和循环的TF在这些过程中的作用。这些研究将有助于确定smc衍生的TF和循环TF在介导心血管病理中的作用，并为设计针对TF的治疗方法提供有用的见解。

DESCRIPTION (provided by applicant): Tissue Factor (TF), the initiator of the coagulation cascade, plays a critical role in hemostasis and thrombosis. There are numerous sources of TF in the vasculature, including macrophages, endothelial cells, and smooth muscle cells (SMC). In addition, TF circulates on procoagulant microparticles (MPs). It is likely that different sources of TF are critical to each pathologic process mediated by TF. This proposal focuses on SMC-derived TF. TF is regulated as a primary response to growth factors and cytokines in SMC, and is upregulated in arterial SMC in response to injury. TF has been implicated as a mediator of SMC migration and its inhibition reduces intimal hyperplasia in response to injury in a variety of animal models. TF is abundant in the media and intima of atherosclerotic plaques and SMC-derived TF is thought to contribute to the large burden of TF in the lipid-rich necrotic core. Therefore TF may play a role in plaque progression and may mediate thrombosis in association with plaque rupture. We have recently developed a mouse, TF/Sm221Cre, that has a >95% deficiency in SMC-derived TF. This mouse develops normally, has no obvious abnormalities of hemostasis, but has a marked reduction in arterial thrombosis induced by FeCl3 injury. SMC from these mice fail to migrate in response to factor (F) VIIa. Our preliminary data suggest that this mouse has reduced intimal hyperplasia in response to wire injury, and surprisingly develops more severe aneurysms in response to angiotensin II (Ang II). We hypothesize that SMC-derived TF may play a number of roles in mediating cardiovascular pathology, including direct effects on SMC physiology, indirect effects through the generation of thrombin, and as a source of procoagulant activity. The TF/Sm221Cre mouse enables us to explore the different roles of SMC-derived TF and determine the relative contribution of SMC- derived TF vs. circulating TF in a variety of pathologic states. Aim 1 will determine the mechanism by which inhibition of SMC-derived TF leads to a reduction in intimal hyperplasia and utilize transplantation with bone marrow from mice with a 99% global reduction of TF and pharmacologic inhibition of TF to explore the relative contributions of SMC-derived and blood TF to this process. This aim will also examine in depth FVIIa signaling in cultured SMC and determine the cellular mechanism(s) underlying TF-mediated SMC migration. Aim 2 will establish the role of SMC-derived TF in mediating abdominal aortic aneurysms (AAA). To facilitate these experiments, the TF/Sm221Cre mice will be bred into the LDLR-/- background. Aim 3 will utilize this mouse to determine the role of SMC-derived TF in mediating the development and progression of atherosclerosis. Aim 4 will test the hypothesis that different types of thrombosis (macrovascular vs. microvascular, venous vs. arterial) involve different mechanisms and will further define the role of SMC-derived and circulating TF in these processes. These studies should help define the role of SMC-derived TF and circulating TF in mediating cardiovascular pathology and provide insights that may be useful in designing therapies targeted at TF. PUBLIC HEALTH RELEVANCE: This proposal examines the biology of tissue factor, the molecule that initiates blood coagulation. Tissue factor is thought to play a major role in coronary thrombosis, the leading cause of heart attacks, and venous thromboembolism, the second leading cause of death in patients with cancer.