Role of Adenosine Receptors in Tissue Protection

A3腺苷受体(AR)是最近发现的嘌呤核苷受体的亚型 腺苷，它的生理功能仍然很差，特别是在 心血管系统。在以前的研究中，我们已经证明了给予选择性激动剂 A3AR有效减轻多种不同临床前心肌缺血动物模型的损伤 再灌流。我们在研究中观察到的A3AR疗法的主要优势之一是 药物在不会对血液动力学产生不利影响的剂量下是有效的。这项提议的目标是 通过完成三个高度集成的功能，进一步扩大我们对A3AR心脏保护作用的了解 明确的目标。在具体目标#1中，我们将扩展我们正在进行的研究，通过以下方式探索潜在的机制 A3AR的激活对脑缺血/再灌注损伤有保护作用。在获得的信息基础上构建 在之前的授予周期中，我们将测试A3AR激活减弱致死性再灌注的假设 抑制炎症损伤和中性粒细胞介导的组织损伤。这一假设将通过以下方式进行检验 新的遗传工具，允许小鼠中性粒细胞中A3AR的特定删除。特定目标的结果 #2将提供重要信息，进一步探索A3AR激动剂的翻译潜力 治疗缺血性心脏病。我们将确定心肌梗死后是否使用A3AR激动剂治疗 在心功能和A3AR是否直接激活方面产生长期保存 减少适应不良的重塑反应。最终的高度创新的具体目标将考验 最近开发的新的A3AR配体的心脏保护作用。我们将研究 具有修饰的(N)-甲基卡巴环结构的一系列新的嘌呤激动剂的成员在 核糖的位置，我们已经确定这是物种独立的，高度选择性的A3AR激动剂。这个 实验是独一无二的，用来检验化合物与聚合物树状大分子的偶联 将通过促进协作性配体-受体相互作用来增加其心脏保护效力和疗效。 最后，我们将研究变构增强剂对A3AR的有用性。这些代理作用于不同的 A3AR蛋白的结合部位，增加作用于立位结合部位的激动剂的亲和力 腺苷。从理论上讲，变构增强剂提供了靶向病变组织的机会 腺苷的产生增加，同时避免由激活受体引起的潜在副作用 其他器官。总体而言，这项建议的中心目标是研究血管紧张素转换酶的病理生理学作用。 心肌缺血/再灌注损伤时心血管和免疫系统中的A3AR。如果我们的 假设是正确的，我们将证明A3AR激活通过抗再灌注损伤减少致命性再灌注损伤 炎症机制和A3AR激动剂的治疗除了缩小梗塞面积外，还将提供 减少梗死后适应不良重塑的额外好处。完成这项工作将具有重要意义 增加我们对A3AR的基本生物学的了解，并有潜力引领这一发展 为治疗缺血性心脏病患者提供新的药理策略。

The A3 adenosine receptor (AR) is the most recently identified subtype of receptor for the purine nucleoside adenosine, which remains poorly characterized in terms of its physiological function, particularly in the cardiovascular system. In previous studies, we have demonstrated that administering selective agonists of the A3AR effectively reduces injury in multiple different preclinical animal models of myocardial ischemia and reperfusion. One of the major advantages of A3AR therapy we have observed in our studies is that these agents are effective at doses that exert no adverse hemodynamic effects. The goal of this proposal is to further expand our knowledge of the cardioprotective actions of the A3AR by completing three highly integrated specific aims. In Specific Aim #1, we will extend our ongoing studies to explore potential mechanisms by which A3AR activation provides protection from ischemia/reperfusion injury. Building off of information gained during the previous grant cycle, we will test the hypothesis that A3AR activation attenuates lethal reperfusion injury by suppressing inflammation and neutrophil-mediated tissue injury. This hypothesis will be tested using novel genetic tools allowing for specific deletion of the A3AR in neutrophils in mice. The results of Specific Aim #2 will provide important information that will further explore the translational potential of A3AR agonists for treating ischemic heart disease. We will determine whether or not treating with A3AR agonists post-MI produces long-term preservation in cardiac performance and whether or not A3AR activation directly diminishes maladaptive remodeling responses. The final highly innovative specific aim will test the cardioprotective efficacy of new A3AR ligands that have recently been developed. We will examine the effectiveness of members of a new series of purine agonists with a modified (N)-methanocarba ring structure in place of the ribose, which we have identified as species-independent, highly selective A3AR agonists. The experiments are uniquely designed to examine whether conjugating the compound to a polymeric dendrimer will increase its cardioprotective potency and efficacy by promoting cooperative ligand-receptor interactions. Finally, we will examine the usefulness of allosteric enhancers for the A3AR. These agents act on a distinct binding site of the A3AR protein that increases the affinity of agonists acting at the orthostatic binding site for adenosine. Theoretically, allosteric enhancers offer the opportunity to target diseased tissues where the production of adenosine is increased while avoiding potential side effects caused by activation of receptors in other organs. Overall, the central objective of this proposal is to investigate the pathophysiological role of the A3AR in the cardiovascular and immune systems during myocardial ischemia/reperfusion injury. If our hypotheses are correct, we will demonstrate that A3AR activation reduces lethal reperfusion injury through anti- inflammatory mechanisms and that treating with A3AR agonists will provide, in addition to infarct size reduction, an added benefit to reduce post-infarction maladaptive remodeling. Completing this work will importantly increase our understanding of the basic biology of the A3AR and has the potential to lead to the development of novel new pharmacological strategies for treating patients with ischemic heart disease.