Smooth Muscle Cell Tissue Factor and Cardiovascular Disease

描述（由申请方提供）：组织因子（TF）是凝血级联反应的起始物，在止血和血栓形成中起关键作用。血管系统中有许多TF来源，包括巨噬细胞、内皮细胞和平滑肌细胞（SMC）。此外，TF在促凝血微粒（MP）上循环。不同来源的TF可能对TF介导的每种病理过程都至关重要。该建议侧重于SMC衍生的TF。TF在SMC中作为对生长因子和细胞因子的主要应答而被调节，并且在动脉SMC中响应于损伤而上调。TF被认为是SMC迁移的介质，在多种动物模型中，TF的抑制可减少损伤后内膜增生。TF在动脉粥样硬化斑块的中膜和内膜中含量丰富，SMC来源的TF被认为是导致富含脂质的坏死核心中TF的大量负担的原因。因此，TF可能在斑块进展中发挥作用，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/Sm 221 Cre，其具有>95%的SMC衍生TF缺陷。该小鼠发育正常，没有明显的止血异常，但FeCl 3损伤诱导的动脉血栓形成明显减少。来自这些小鼠的SMC不能响应于因子（F）VIIa而迁移。我们的初步数据表明，这只小鼠因导丝损伤而减少了内膜增生，并令人惊讶地因血管紧张素II（Ang II）而形成了更严重的动脉瘤。我们假设SMC衍生的TF可能在介导心血管病理学中发挥许多作用，包括对SMC生理学的直接影响，通过凝血酶产生的间接影响，以及作为促凝血活性的来源。TF/Sm 221 Cre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SMC衍生的TF抑制导致内膜增生减少的机制，并利用TF总体减少99%的小鼠骨髓移植和TF的药理学抑制来探索SMC衍生的TF和血液TF对该过程的相对贡献。该目的还将深入研究培养的SMC中的FVIIa信号传导，并确定TF介导的SMC迁移的细胞机制。目的2将确定SMC衍生的TF在介导腹主动脉瘤（AAA）中的作用。为了促进这些实验，TF/Sm 221 Cre小鼠将在LDLR-/-背景下繁殖。目的3将利用这只小鼠来确定SMC衍生的TF在介导动脉粥样硬化的发生和发展中的作用。目的4将检验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衍生和循环TF在这些过程中的作用。这些研究应有助于确定SMC衍生的TF和循环TF在介导心血管病理学中的作用，并提供可能有助于设计针对TF的治疗方法的见解。 公共卫生相关性：该提案研究组织因子的生物学，组织因子是启动血液凝固的分子。组织因子被认为在冠状动脉血栓形成（心脏病发作的主要原因）和静脉血栓栓塞（癌症患者死亡的第二大原因）中起主要作用。

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.