Mechanisms of Arterial Wall-Mediated Atherogenesis

描述（由申请人提供）：动脉粥样硬化涉及内皮细胞、平滑肌细胞（SMC）、巨噬细胞和T淋巴细胞，但这些细胞类型对动脉粥样硬化斑块形成的个体作用在很大程度上仍然是个谜。该项目的目标是研究动脉壁对动脉粥样硬化的贡献，并开发一种研究该过程重要基因的方法。三（3）种这样的基因是编码肿瘤坏死因子-α（TNF）和TNF的2种已知受体的基因，TNF是由巨噬细胞和SMC分泌的炎性细胞因子。TNF在动脉粥样硬化形成中的重要性通过其促进C-反应蛋白分泌的作用而突出，C-反应蛋白的血清水平是突发心肌梗死的最佳单一预测因子。为了验证SMC TNF受体介导的信号传导对动脉粥样硬化形成有重要作用的假设，我们将使用2个模型系统。首先，我们的体内模型将在载脂蛋白E缺陷（Apoe-/-）小鼠中使用颈动脉间置移植，其发展颈动脉粥样硬化。移植物将是源自同源小鼠的颈动脉，所述同源小鼠是（a）野生型（阴性对照）、（B）TNF受体-1缺陷型（Tnfr 1-/-）、（c）Tnfr 2-/-或（d）Tnfr 1-/-. Tnfr 2-/-。通过比较动脉粥样硬化的时间进程，程度和斑块细胞组成，在这些移植物中，我们建议评估动脉壁TNFRs在动脉粥样硬化形成中的作用。第二，我们的动脉粥样硬化体外模型将使用巨噬细胞/SMC共培养物来评估SMC和巨噬细胞TNFR在活化的巨噬细胞引起的基因表达和SMC的致动脉粥样硬化活性（增殖、迁移和清道夫受体活性）中的作用。用于共培养的巨噬细胞和原代主动脉SMC均来自上述每种小鼠系，并且巨噬细胞将被氧化低密度脂蛋白激活。因此，该项目将（i）创建一个模型系统，可以测试特定基因是否有助于动脉壁介导的动脉粥样硬化形成;（ii）阐明动脉壁TNFRs在动脉粥样硬化形成中的作用;（iii）识别SMC基因表达的激活巨噬细胞分泌的因子。在这样做的过程中，这个项目应该建立一个基础，以确定多种动脉壁基因产物，可能作为动脉粥样硬化的治疗目标。

DESCRIPTION (provided by applicant): Atherosclerosis involves endothelial cells, smooth muscle cells (SMCs), macrophages, and T lymphocytes, but the individual contributions of these cell types to atherosclerotic plaque formation remains largely enigmatic. The goal of this project is to examine the contribution of the arterial wall to atherosclerosis, and to develop an approach for studying the genes important to this process. Three (3) such genes are those encoding tumor necrosis factor-a (TNF) and the 2 known receptors for TNF, an inflammatory cytokine secreted by both macrophages and SMCs. The importance of TNF in atherogenesis is highlighted by its role in promoting the secretion of C-reactive protein, serum levels of which are the best single predictors of incident myocardial infarction. To test the hypothesis that SMC TNF receptor-mediated signaling contributes significantly to atherogenesis, we will use 2 model systems. First, our in vivo model will use carotid interposition grafting in apolipoprotein E-deficient (Apoe-/-) mice, which develop carotid artery atherosclerosis. The grafts will be carotid arteries derived from congenic mice that are either (a) wild type (negative controls), (b) TNF receptor-1-deficient (Tnfr1-/-), (c) Tnfr2-/-, or (d) Tnfr1-/-.Tnfr2-/-. By comparing the atherosclerosis time course, extent, and plaque cellular composition in each of these grafts, we propose to assess the role of arterial wall TNFRs in atherogenesis. Second, our in vitro model of atherosclerosis will use macrophage/SMC co-cultures to assess the role of SMC and macrophage TNFRs in activated macrophage elicited gene expression and atherogenic activities of SMCs: proliferation, migration, and scavenger receptor activity. Both macrophages and primary aortic SMCs for co-culture will derive from each of the mouse lines described above, and macrophages will be activated by oxidized low-density lipoprotein. Thus, this project will (i) create a model system that can test whether specific genes contribute to arterial wall-mediated atherogenesis; (ii) elucidate the roles of arterial wall TNFRs in atherogenesis; and (iii) discern SMC genes expressed in response to factors secreted by activated macrophages. In so doing, this project should build a foundation for identifying multiple arterial wall gene products that may serve as therapeutic targets for atherosclerosis.