Role of Adenosine Receptors in Tissue Protection

描述(由申请人提供)：目前的证据表明，A3腺苷受体(A3AR)在心肌细胞中表达，在那里它们调节对缺血应激的反应。此外，A3AR在参与炎症反应的细胞中表达，包括中性粒细胞、巨噬细胞和内皮细胞。在这些细胞中，它们发挥抗炎作用。在初步研究中，我们已经证明，新开发的A3AR激动剂对小鼠、兔和狗的心肌缺血/再灌注(I/R)损伤所致的组织损伤具有深刻的心脏保护作用，无论是在缺血前还是在再灌流时给予。这项研究计划的目标是了解这种组织保护的机制。我们的一般假设是，A3AR激动剂对心肌细胞起双重作用，以减少缺血时的心肌损伤，并作用于骨髓来源的细胞，以减少再灌流期间的炎症。这些研究涉及使用遗传学方法：1)使用Cre/loxP策略从心肌细胞中选择性地删除A3AR基因的同源系小鼠，以及2)使用标准移植技术从同源A3AR基因“敲除”的小鼠中产生在骨髓来源的细胞中缺失或表达A3AR的嵌合小鼠。在体小鼠脑梗塞模型和离体鼠全心缺血再灌流模型将被用来确定在心肌中表达的A3ARs与炎症细胞在调节I/R损伤中的相对重要性。建议进行更多的研究，以研究A3AR在“野生型”、传统的A2AAR基因“敲除”和传统的A3AR基因敲除的小鼠的特定炎性细胞群中的细胞信号反应。这些研究将结合几种最先进的技术，提供关于A3AR激活提供对I/R损伤的保护的细胞特异性机制的新的明确信息。

DESCRIPTION (provided by applicant): Current evidence suggests that A3 adenosine receptors (A3ARs) are expressed in cardiac myocytes, where they regulate responses to ischemic stress. In addition, A3ARs are expressed in cells involved in the inflammatory response including neutrophils, macrophages, and endothelial cells. In these cells, they mediate anti-inflammatory actions. In preliminary studies, we have shown that newly developed A3AR agonists provide profound cardiac protection against tissue damage induced by myocardial ischemia/reperfusion (I/R) injury in mice, rabbits, and dogs whether they are given prior to ischemia or at the time of reperfusion. The goal of this research proposal is to understand the mechanisms responsible for this tissue protection. Our general hypothesis is that A3AR agonists act dually on cardiac myocytes to reduce myocardial injury during ischemia, and act on bone marrow-derived cells to reduce inflammation during reperfusion. The studies involve the use of genetic approaches to: 1) produce a congenic line of mice with the A3AR gene selectively deleted from cardiomyocytes using the Cre/LoxP strategy, and 2) to produce from congenic A3AR gene "knock-out" mice, chimeric mice lacking or expressing the A3AR in bone marrow-derived cells using standard transplantation techniques. An in vivo mouse model of infarction and an isolated mouse heart model of global ischemia and reperfusion will be used to determine the relative importance of A3ARs expressed in the myocardium versus inflammatory cells in regulating I/R injury. Additional studies are proposed to study cellular signaling responses of A3ARs in specific populations of inflammatory cells from "wild-type", conventional A2AAR gene "knock-out", and conventional A3AR gene knock-out" mice. Collectively, these studies will combine several state-of-the-art techniques to provide new definitive information on the cell-specific mechanisms by which A3AR activation provides protection from I/R injury.