PROJECT III - ROLE OF NATURAL ANTIBODY IN REPERFUSION INJURY

缺血再灌注损伤(I/R)是血管内皮细胞的炎症性损伤。 缺氧组织再灌流后的实质组织。这种综合征导致各种组织的急性和慢性损伤，包括心肌、中枢神经系统、后肢和肠道。对啮齿动物模型的研究表明，补体系统是损伤的主要媒介(1-3)。血清天然免疫球蛋白M在诱导两个不同组织的损伤以激活补体(3，4)方面也是关键的。一个 解释这些观察结果的普遍机制是低氧内皮细胞表达与自然IgM特异结合的新抗原，导致经典的补体途径和炎症反应的激活。这个项目将在三个相互关联的具体目标中检验这一假设。 第一个目的将验证我们的假设，即天然IgM介导局部I/R损伤，主要来源是CD11b+腹膜B-1细胞。这一目标将包括鉴定B-1细胞杂交瘤，该杂交瘤分泌导致体内I/R损伤的IgM。一株表达特异性抗体的杂交瘤克隆(CM22)已被鉴定，并将在第二个目标中进一步鉴定。我们将通过不同的遗传途径解偶联与缺血组织的IgM结合和补体途径的激活。在最终目标中，我们将研究表达缺血特异性抗自身抗体的B细胞亚群的发展和调节。这项拟议的研究非常重要，因为它不仅将为我们进一步了解缺血再灌注损伤的病因提供重要的试剂和小鼠模型，而且有望找到一种治疗方法来干预这一人类的主要疾病。

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.