Mechanisms of Arterial Wall-Mediated Atherogenesis

描述(申请人提供)：动脉粥样硬化涉及内皮细胞、平滑肌细胞(SMCs)、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贡献在很大程度上仍然是个谜。这个项目的目标是研究动脉壁在动脉粥样硬化中的作用，并开发一种研究这一过程中重要基因的方法。三(3)个这样的基因是编码肿瘤坏死因子(TNF)的基因，以及已知的两个肿瘤坏死因子受体，肿瘤坏死因子是一种由巨噬细胞和SMC分泌的炎性细胞因子。肿瘤坏死因子在动脉粥样硬化形成中的重要作用是促进C反应蛋白的分泌，而C反应蛋白的血清水平是预测心肌梗死发生的最佳单一指标。为了验证SMC肿瘤坏死因子受体介导的信号在动脉粥样硬化形成中的重要作用这一假设，我们将使用两个模型系统。首先，我们的体内模型将在发生颈动脉粥样硬化的载脂蛋白E缺陷(APOE-/-)小鼠身上使用颈动脉间置移植。移植物将是来自(A)野生型(阴性对照)、(B)肿瘤坏死因子受体-1缺陷(Tnfr1-/-)、(C)Tnfr2-/-或(D)Tnfr1-/-.Tnfr2-/-的同种小鼠的颈动脉。通过比较这些移植物中动脉粥样硬化的时间进程、程度和斑块细胞成分，我们建议评估动脉壁TNFR在动脉粥样硬化形成中的作用。其次，我们的动脉粥样硬化体外模型将使用巨噬细胞/SMC共培养来评估SMC和巨噬细胞TNFR在激活的巨噬细胞诱导的基因表达和SMC的致动脉粥样硬化活性中的作用：增殖、迁移和清道夫受体活性。用于共培养的巨噬细胞和原代主动脉SMCs将来自上述每一种小鼠系，巨噬细胞将被氧化低密度脂蛋白激活。因此，该项目将(I)建立一个模型系统，可以测试特定基因是否参与动脉壁介导的动脉粥样硬化；(Ii)阐明动脉壁TNFR在动脉粥样硬化形成中的作用；以及(Iii)识别SMC基因对激活的巨噬细胞分泌的因子的反应。通过这样做，该项目应该为鉴定可能作为动脉粥样硬化治疗靶点的多种动脉壁基因产物奠定基础。

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.