PROJECT III - ROLE OF NATURAL ANTIBODY IN REPERFUSION INJURY

缺血-再灌注损伤（I/R）代表对内皮的炎性损伤和潜在的血管损伤。 缺氧组织再灌注后的实质组织。这种全身综合征可引起包括心肌、中枢神经系统、后肢和肠在内的各种组织的急性和慢性损伤。在啮齿动物模型中的研究表明补体系统是损伤的主要介质（1 - 3）。血清天然IgM在两种不同组织中诱导损伤以激活补体中也是至关重要的（3，4）。一 解释这些观察结果的普遍机制是缺氧内皮表达特异性结合天然IgM的新抗原，导致补体经典途径和炎症反应的激活。本项目将在三个相互关联的具体目标中检验这一假设。 第一个目的是检验我们的假设，即天然IgM介导局部I/R损伤，主要来源是CD 11 B+腹膜B-1细胞。这一目标将包括鉴定分泌诱导体内I/R损伤的IgM的B-1细胞杂交瘤。已经鉴定了一个表达特异性抗体的杂交瘤克隆（CM 22），并将在第二个目的中对其进行进一步表征。我们将使用各种遗传学方法解偶联IgM与缺血组织的结合和补体途径的激活。在最后的目标中，我们将检查表达缺血特异性抗自身抗体的B细胞亚群的发育和调节。拟议的研究是重要的，因为它不仅将提供重要的试剂和小鼠模型，进一步了解缺血再灌注损伤的病因，但希望导致识别的治疗方法，以干预这一重大疾病的人类。

Ischemia-reperfusion injury (I/R) represents inflammatory injury to the endothelium and underlying parenchymal tissues following reperfusion of hypoxic tissues. This general syndrome is responsible for both acute and chronic injury to various tissues including the myocardium, central nervous system, hind limb andintestine. Studies in rodent models implicate the complement system as a major mediator of injury (1-3). Serum natural IgM is also critical in the induction of injury in two distinct tissues for activation of complement (3, 4). A universal mechanism that would explain these observations is that the hypoxic endothelium expresses neoantigens that specifically bind natural IgM leading to activation of the classical pathway of complement and the inflammatory response. This project will test this hypothesis in three inter-related specific aims. The first aim will test our hypothesis that natural IgM mediates local I/R injury and that a major source is CD11b+ peritoneal B-1 cells. This aim will include identification of B-1 cell hybridomas that secrete IgM that induce I/R injury in vivo. One hybridoma clone (CM22) expressing specific antibody has been identified and it will be further characterized in the second aim. We will uncouple IgM binding to ischemic tissues and activation of complement pathway using various genetic approaches. In the final aim, we will examine the development and regulation of B cell subsets that express ischemia-specific anti-self-antibody. The proposed study is important as it will not only provide important reagents and murine models for furthering our understanding of the etiology of ischemia reperfusion injury but hopefully lead to the identification of a therapeutic approach to intervene in this major disorder of humans.