Adenosine Receptors and Atherogenesis

描述（由申请人提供）：腺苷与腺苷酸环化酶刺激性（A2型）腺苷受体（AR）结合可诱导冠状血管舒张，抑制人主动脉血管平滑肌细胞增殖，并影响动脉壁基质生成，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A2 bAR在体内调节血管病理学中的作用在我们的研究之前还没有被检查过。为了进一步解决这个问题，我们产生了第一个A2 bAR敲除（KO）/报告基因敲入小鼠模型，并显示主要在VSMC和巨噬细胞中报告的基因表达，与对照小鼠的内源性谱一致。与年龄、性别和品系匹配的对照小鼠相比，促炎细胞因子（如肿瘤坏死因子-1（TNF-1））的增加是观察到的这些A2 bAR KO小鼠血管系统中白细胞粘附上调的潜在机制。另一方面，A2 bAR基因受体本身是由TNF-1诱导的，表明存在一个调节环。A2 bAR KO小鼠在导丝诱导的股动脉损伤后显示出更大的病变形成。这与CXCR 4的上调有关，CXCR 4是一种已知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性细胞向血管动员的蛋白质。此外，骨髓（BM）移植实验表明，炎症反应和血管病变的形成显着调节BM衍生的A2 bAR。基于这些新的发现，我们假设A2 bAR介导的信号调节CXRC 4的表达，因此，在血管病变形成中起着至关重要的作用。我们的论点是，巨噬细胞A2 bAR通过其控制炎性细胞因子水平的能力，能够显著地保护自身免受血管病变，这与BM移植实验一致。最后，确定TNF-1对A2 bAR基因调控的机制将为炎症过程中控制血管功能障碍的策略的发展指明方向。提出了三个具体的研究目标：目标1。研究骨髓细胞和/或其信号在介导A2 bAR对血管损伤和动脉粥样硬化病变形成的影响中的直接参与，并研究相关机制，重点是巨噬细胞A2 bAR的贡献。目标2.阐明A2 bAR调控CXCR 4/SDF-1轴的机制。目标3：目的：研究肿瘤坏死因子-1（TNF-1）在原代培养和体内对A2 bAR基因的激活机制。综上所述，我们提出的研究应该揭示A2 bAR在血管功能障碍发病机制中的作用，并将注意力集中在A2 bAR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。我们的研究计划建立在新的发现之上，包括A2 b腺苷受体对动脉粥样硬化/再狭窄的保护作用的鉴定。导致这种保护的机制和该受体基因表达的控制是本提案的研究重点。

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.