Adenosine Receptors and Atherogenesis

描述(申请人提供)：腺苷与腺苷环化酶刺激性(A2型)腺苷受体(AR)结合可诱导冠状动脉扩张，抑制人主动脉血管平滑肌细胞的增殖，并影响动脉壁基质的产生，所有这些都是动脉粥样硬化/再狭窄的重要组成部分。低亲和力A2bARs在体内调节血管病理中的作用在我们的研究之前还没有被检验过。为了进一步解决这个问题，我们建立了第一个A2bAR基因敲除(KO)/报告基因敲入小鼠模型，并显示了已报道的基因主要在VSMC和巨噬细胞中表达，与对照组小鼠的内源性特征一致。与年龄、性别和品系匹配的对照组小鼠相比，促炎症细胞因子，如肿瘤坏死因子-1(TNF-1)的增强是观察到的这些A2bAR KO小鼠血管中白细胞黏附上调的根本机制。另一方面，A2bAR基因受体本身是由肿瘤坏死因子-1诱导的，这意味着一个调节环路。A2bAR KO小鼠在导丝诱导的股动脉损伤后表现出更大的病变形成。这与CXCR4的上调有关，CXCR4是一种已知的蛋白质，通过与其配体基质细胞衍生因子-1(SDF-1)相互作用，促进祖细胞和炎症细胞到血管上的动员。此外，骨髓(BM)移植实验表明，BM来源的A2bARs显著调节炎症反应和血管病变的形成。基于这些新的发现，我们假设A2bAR介导的信号调节CXRC4的表达，因此在血管病变的形成中起着至关重要的作用。我们认为，巨噬细胞A2bARs通过其控制炎症细胞因子水平的能力，能够显著地保护自己免受血管病变的影响，这与骨髓移植实验是一致的。最后，确定肿瘤坏死因子-1调节A2bAR基因的机制将引领控制炎症过程中血管功能障碍的策略的发展。目的1.研究A2bAR在血管损伤和动脉粥样硬化病变形成中的直接作用，并探讨其相关机制，重点探讨巨噬细胞A2bARs的作用。目的2.阐明A2bAR对CXCR4/SDF-1轴的调控机制。目的3.研究肿瘤坏死因子-1在原代培养和体内激活A2bAR基因的机制。综上所述，我们拟议的研究将为A2bARs在血管功能障碍发病机制中的作用提供新的线索，并可能将注意力集中在A2bAR的激活作为治疗靶点上。公共卫生相关性：动脉粥样硬化是西方世界血管疾病的主要原因。我们的研究建议建立在新发现的基础上，包括鉴定A2B腺苷受体对动脉粥样硬化/再狭窄具有保护作用。导致这种保护和控制该受体基因表达的机制是本提案中研究的重点。

DESCRIPTION (provided by applicant): Adenosine binding to adenylyl cyclase stimulatory (A2-type) adenosine receptors (ARs) induces coronary vasodilatation, inhibits human aortic vascular smooth muscle cell proliferation, and affects arterial wall matrix production, all of which are important components of atherosclerosis/restenosis. The role of the low affinity A2bARs in regulating vascular pathology in vivo had not been examined prior to our study. To further address this, we generated the first A2bAR-knockout (KO)/reporter gene-knock-in mouse model and showed reported gene expression primarily in VSMC and macrophages, in accordance with the endogenous profile in control mice. Augmentation of proinflammatory cytokines, such as tumor necrosis factor-1 (TNF-1), is the underlying mechanism for an observed upregulation of leukocyte adhesion in the vasculature of these A2bAR KO mice, as compared with age-, sex-, and strain-matched control mice. On the other hand, the A2bAR gene receptor, itself, is induced by TNF-1, suggesting a regulatory loop. A2bAR KO mice display greater lesion formation after guidewire-induced femoral artery injury. This occurs in association with the upregulation of CXCR4, a protein known to promote mobilization of progenitors and inflammatory cells to the vessel by interaction with its ligand stromal cell-derived factor-1 (SDF-1). Furthermore, bone marrow (BM) transplantation experiments indicate that the inflammatory response and vascular lesion formation are significantly regulated by BM-derived A2bARs. Building upon these novel findings, we hypothesize that A2bAR-mediated signaling regulates the expression of CXRC4 and, hence, plays a vital role in vascular lesion formation. It is our contention that macrophage A2bARs, via their ability to control the level of inflammatory cytokines, are capable of significantly protecting against vascular pathology on their own, consistent with the BM transplantation experiments. Finally, identifying mechanisms of A2bAR gene regulation by TNF-1 should lead the way for the development of strategies for controlling vascular dysfunction during inflammation. Three specific aims of research are proposed: Aim 1. To examine the direct participation of BM cells and/or their signals in mediating effects of the A2bAR on lesion formation during vascular injury and atherosclerosis, and to study related mechanisms, with a focus on the contribution of macrophage A2bARs. Aim 2. To elucidate the mechanism of control of the CXCR4/SDF-1 axis by the A2bAR. Aim 3. To study the mechanism of A2bAR gene activation by TNF-1 in primary cultures and in vivo. Taken together, our proposed investigations should shed new light on the role of A2bARs in the pathogenesis of vascular dysfunction, and could focus attention on A2bAR activation as a therapeutic target. PUBLIC HEALTH RELEVANCE: Atherosclerosis is a leading cause of vascular disease in the Western world. Our research proposal builds upon novel findings, including the identification of the A2b adenosine receptor as protective against atherosclerosis/restenosis. The mechanisms leading to this protection and the control of expression of this receptor gene are the focus of research in this proposal.