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

描述（改编自申请人摘要）：为了回应 炎症刺激，中性粒细胞被激活，导致增加 趋化性，产生有毒的氧代谢物， IgG Fc受体（FcR）和补体受体功能的上调。 尽管这些中性粒细胞反应对于宿主防御至关重要，但它们 也导致导致许多疾病的显著组织损伤 流程. 体内研究表明，单克隆抗体 (mAb)阻断白细胞表面受体家族β 2 整合素，可以显着减少这种组织破坏， 炎症部位。 申请人的体外研究表明， CR 3通过IgG FcR参与嗜中性粒细胞活化，包括 趋化因子和促炎性LTB 4的产生， FcR依赖的粘附和吞噬作用。 为了研究 这种FcR/CR 3相互作用的分子机制，转染系统 已经开发了模拟FcRII和 中性粒细胞CR 3。 在该系统中，FcR介导的吞噬作用仅 在CR 3转染的细胞中发生。 最近的数据显示， 特定的细胞骨架蛋白桩蛋白被酪氨酸磷酸化 在转染的K562和PMN中以CR 3依赖的方式。 此外，CR 3转染子显示其他细胞因子的普遍降低。 与对照相比，含有磷酸酪氨酸的蛋白质。 在 此外，IgG调理颗粒的吞噬作用在CR 3 与白细胞酪氨酸磷酸酶SHP共转染。 一起 这些数据表明，CR 3参与调节的假设， 酪氨酸磷酸化与中性粒细胞活化有关。 的 申请人建议将CR 3中的域本地化， 与FcRII的合作，并测试CR 3效应 对FcRII功能的影响是通过调节酪氨酸磷酸化。 为了实现这些目标，申请人建议（1）确定 CR 3突变对补体和IgG依赖性吞噬作用的影响， 粘附和细胞骨架协会;（2）研究CR 3的作用 在酪氨酸磷酸化的调节，和（3）表征 酪氨酸磷酸酶（SHP）转染细胞的吞噬功能。 了解FcRII和CR 3之间的相互作用机制可能是 可用于设计控制炎性组织损伤的策略。 相互作用或其后果的药理学抑制具有 可能会受到影响，同时不会影响 中性粒细胞与内皮细胞的CR 3依赖性粘附， 正常的宿主防御 潜在应用非常广泛，包括 治疗自身免疫性疾病，以及保护心肌 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.