Smooth Muscle Cell Tissue Factor and Cardiovascular Disease

说明(申请人提供)：组织因子(TF)是凝血级联反应的起始者，在止血和血栓形成中起着关键作用。血管内有多种来源的转铁蛋白，包括巨噬细胞、内皮细胞和平滑肌细胞(SMC)。此外，转铁蛋白在促凝剂微粒(MPS)上循环。可能不同来源的转铁蛋白在转铁蛋白介导的每一种病理过程中都是至关重要的。本提案重点介绍了SMC衍生的转移因子。Tf在SMC中作为对生长因子和细胞因子的主要反应而被调节，在动脉SMC中作为对损伤的反应而上调。在多种动物模型中，Tf被认为是SMC迁移的中介物，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中层和内膜中含量丰富，SMC来源的Tf被认为是富含脂质的坏死区Tf的主要来源。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/Sm221Cre，它的SMC来源的Tf有95%的缺陷。该小鼠发育正常，无明显的止血异常，但对FeCl3损伤所致的动脉血栓形成有明显的减轻作用。这些小鼠的SMC不能对因子(F)VIIa做出反应。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，而令人惊讶的是，由于血管紧张素II(Ang II)的反应，该小鼠发生了更严重的动脉瘤。我们推测，SMC来源的TF可能在介导心血管病理过程中发挥多种作用，包括对SMC生理的直接作用，通过产生凝血酶的间接作用，以及作为促凝血活性的来源。Tf/Sm221Cre小鼠使我们能够探索SMC来源的Tf的不同作用，并确定SMC来源的Tf与循环Tf在各种病理状态下的相对贡献。目的1探讨抑制SMC来源的转铁蛋白(Tf)抑制血管内膜增生的机制，并利用Tf整体下降99%的小鼠骨髓移植和Tf的药理抑制来探讨SMC来源的Tf和血液Tf在此过程中的相对贡献。这一目标还将深入研究培养的SMC中的FVIIa信号，并确定TF介导的SMC迁移的细胞机制(S)。目的2研究SMC来源的转铁蛋白在腹主动脉瘤(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来源的转铁蛋白在介导动脉粥样硬化的发生和发展中的作用。目的4将检验这一假说，即不同类型的血栓形成(大血管与微血管、静脉与动脉)涉及不同的机制，并将进一步确定SMC来源的和循环中的因子在这些过程中的作用。这些研究应该有助于确定SMC来源的转铁蛋白和循环转铁蛋白在介导心血管病理中的作用，并提供可能有助于设计针对转铁蛋白的治疗方法的见解。 与公共健康相关：这项建议研究了组织因子的生物学，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和静脉血栓栓塞症中起主要作用，前者是心脏病发作的主要原因，后者是癌症患者死亡的第二大原因。

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.