CR3 (MAC-1, CD11B/CD18) AND PHAGOCYTE ACTIVATION

描述(改编自申请人的摘要)：答复 炎性刺激，中性粒细胞被激活，导致 粘附性、趋化性、有毒氧代谢产物的产生和 Ig G Fc受体(FCR)和补体受体功能上调。 尽管这些中性粒细胞反应对宿主防御至关重要，但它们 也会导致严重的组织损伤，导致许多疾病 流程。体内研究表明，单抗 (单抗)阻断白细胞表面受体家族--β2 整合素可以显著减少这种组织破坏 炎症部位。申请人的体外研究表明， CR3通过免疫球蛋白FCRs参与中性粒细胞的激活，包括 趋化因子和促炎因子LTB4的产生及增强 依赖FCR的黏附和吞噬作用。为了调查 FCR/CR3相互作用的分子机制 已经开发出模拟FcRII和FcRII功能相互作用的 中性粒细胞中的CR3。在这个系统中，只有FCR介导的吞噬作用 发生在转CR3的细胞中。最近的数据表明， 特定的细胞骨架蛋白，巴西林，变成酪氨酸磷酸化 在K562和PMN中以CR3依赖的方式表达。 此外，CR3转染者在其他细胞中普遍减少 与对照组相比，含有磷酸酪氨酸的蛋白质。在……里面 此外，当CR3时，免疫球蛋白颗粒的吞噬作用最大。 与白细胞酪氨酸磷酸酶(SHP)共转染。同舟共济 这些数据表明CR3参与调控的假说 与中性粒细胞激活相关的酪氨酸磷酸化。这个 申请人建议将CR3中的域名本地化 与FcRII合作，并检验CR3效应的假设 FcRII的功能是通过调节酪氨酸磷酸化来实现的。 为了实现这些目标，申请人建议(1)确定 CR3突变对补体和免疫球蛋白依赖的吞噬功能的影响 黏附和细胞骨架联系；(2)研究CR3的作用 在调节酪氨酸磷酸化中的作用，以及(3)表征 酪氨酸磷酸酶(SHP)转基因细胞的吞噬功能。 了解FcRII和CR3之间的相互作用机制可能是 有助于设计控制炎性组织损伤的策略。 对这种相互作用或其后果的药物抑制具有 可能是抗炎的，同时不会影响 依赖CR3的PMN与内皮细胞的黏附，这对 正常的宿主防御。潜在的应用相当广泛，包括 自身免疫性疾病的治疗以及心肌的保存 在脑梗塞后。

DESCRIPTION (Adapted from the applicant's abstract): In response to inflammatory stimuli, neutrophils become activated resulting in increased adhesiveness, chemotaxis, generation of toxic oxygen metabolites and upregulation of IgG Fc receptor (FcR) and complement receptor function. Although these neutrophil responses are critical for host defense, they also lead to significant tissue damage contributing to many disease processes. In vivo studies have demonstrated that monoclonal antibody (mAb) blockage of a family of leukocyte surface receptors, the beta2 integrins, can significantly decrease this tissue destruction at inflammatory sites. In vitro studies by the applicant have shown that CR3 is involved in neutrophil activation via the IgG FcRs, including generation of the chemotaxin and proinflammatory LTB4, and augmentation of FcR dependent adhesion and phagocytosis. In order to investigate the molecular mechanism of this FcR/CR3 interaction, a transfection system has been developed that mimics the functional interaction of FcRII and CR3 in neutrophils. In this system, FcR-mediated phagocytosis only occurs in cells transfected with CR3. Recent data demonstrate that a specific cytoskeletal protein, paxillin, becomes tyrosine phosphorylated in a CR3 dependent manner in the transfected K562 and in PMN. Furthermore, CR3 transfectants show a general decrease in other phosphotyrosine containing proteins compared with controls. In addition, phagocytosis of IgG-opsonized particles is maximal when CR3 is cotransfected with the leukocyte tyrosine phosphatase, SHP. Together these data suggest the hypothesis that CR3 is involved in the regulation of tyrosine phosphorylation associated with PMN activation. The applicant proposes to localize the domains in CR3 necessary for cooperation with FcRII, and to test the hypothesis that the CR3 effect on FcRII function is through modulation of tyrosine phosphorylation. To accomplish these goals, the applicant proposes to (1) determine the effect of mutations of CR3 on complement- and IgG-dependent phagocytosis, adhesion, and cytoskeletal associations; (2) investigate the role of CR3 in regulation of tyrosine phosphorylation, and (3) characterize the phagocytic function of tyrosine phosphatase (SHP) transfected cells. Understanding the mechanism of interaction between FcRII and CR3 may be useful in designing strategies to control inflammatory tissue damage. Pharmacologic inhibition of the interaction or its consequences has the possibility of being antiinflammatory and at the same time not affecting CR3-dependent adhesion of PMN to endothelium, which is critical for normal host defense. Potential applications are quite broad including treatment of autoimmune diseases, as well as preservation of myocardium following infarcts.