MECHANISMS OF PMN ACTIVATION MEDIATED BY GMP-140 AND PAF

中性粒细胞(PMN)从血流迁移到 炎症部位是与血管内皮细胞(ECs)的粘连。一个 炎症部位PMN-EC黏附功能受损导致复发 和严重的感染，如发生在有遗传缺陷的人身上 中性粒细胞黏附蛋白，以及在缺陷严重的新生儿中 特色化的。另外，中性粒细胞与内皮细胞的黏附可能导致血管 局部或全脑缺血再灌注损伤、坏死性损伤 小肠结肠炎，或肺透明膜病，继发于支气管肺 发育不良。这种胶粘剂相互作用有两种机制：1) 依赖于液相趋化因子激活PMN；2) 依赖于激活的内皮细胞表达的前黏附分子。越多 生理机制可能依赖于EC的激活 因为它以空间特定的方式瞄准PMN。ECS受以下因素刺激 快速作用的激动剂在其表面表达两个前黏附分子， 颗粒膜蛋白-140与血小板活化因子 (PAF)。表达于EC表面的PAF与其PMN受体结合， 激活中性粒细胞并上调CD11/CD18整合素介导子 粘附力。黏附机制涉及一种新的并列他克林 细胞-细胞相互作用中，细胞相关的PAF充当信号， 激活PMN。GMP-140直到最近才被确定为一种前粘附剂 在快速激活的内皮细胞上表达的分子。初步数据显示 它的表达对于PAF介导的结合的发生和 GMP-140增强PAF刺激的CD11/CD18依赖的黏附。 然而，GMP-140对PMN的影响似乎是复杂的，它可能 抑制PMN-CD11/CD18上调和其他激活反应 一些条件。GMP-140与ITS结合的功能后果 中性粒细胞上的受体尚未确定。这些改动很重要 鉴于GMP-140在PMN的初始黏附中可能发挥的中心作用 炎症部位的ECS。当前项目有4个特定的 目的：1)研究中性粒细胞CD11/CD18黏附分子的变化 连接GMP-140受体所产生的反应；2)确定 GMP-140增强PAF刺激黏附的分子机制(S) 3)描述中性粒细胞功能反应的变化 由于连接GMP-140而发生的黏附和聚集 受体；4)表征新生儿中性粒细胞的应答能力 活化的内皮细胞上表达黏附介质。所获得的信息 在前三个具体目标中，将应用于最后一个具体目标 目标。通过阐明EC-PMN的正常黏附机制，新的 治疗涉及缺陷或缺陷的疾病的治疗策略 未经调节的PMN与EC的黏附可能会形成。此外，这项工作 建议将形成一个项目的基础，这将导致我的发展 作为一名生物医学研究员。

The first step in migration of neutrophils (PMNs) from the blood stream to sites of inflammation is adhesion to vascular endothelial cells (ECs). An impairment in PMN-EC adhesion at sites of inflammation results in recurrent and severe infection such as occurs in individuals with genetic defects in PMN adhesion proteins, and in neonates, where the defect is poorly characterized. Alternatively, PMN adhesion to ECs may lead to vascular injury as in regional or global ischemia-reperfusion injury, necrotizing enterocolitis, or hyaline membrane disease with subsequent bronchopulmonary dysplasia. There are two mechanisms for this adhesive interaction: 1) Dependent on PMN activation by fluid-phase chemotactic factors; 2) Dependent on proadhesive molecules expressed by activated ECs. The more physiologically-relevant mechanism may be that dependent on EC activation because it targets PMNs in a spatially-specific way. ECs stimulated by rapidly-acting agonists express two proadhesive molecules on their surface, granule membrane protein-140 (GMP-140) and platelet activating factor (PAF). PAF expressed on the EC surface binds to its PMN receptor, activating the PMN and upregulating the CD11/CD18 integrins that mediate adhesion. The adhesive mechanism involves a novel example of juxtacrine cell-cell interaction in which cell-associated PAF acts as a signal that activates PMNs. GMP-140 has only recently been identified as a proadhesive molecules expressed on rapidly-activated ECs. Preliminary data indicates that its expression is essential for the PAF-mediated binding to occur and that GMP-140 enhances PAF-stimulated CD11/CD18-dependent adhesion. However, the effect of GMP-140 on PMNs appears to be complex and it may inhibit PMN-CD11/CD18 upregulation and other activation responses under some conditions. The functional consequences of binding of GMP-140 to its receptor on the PMN have not been defined. These alterations are important given the central role GMP-140 may play in the initial adhesion of PMNs to ECs at the site of inflammation. The current project has 4 specific objectives: 1) Characterize the alteration in PMN CD11/CD18 adhesive responses resulting from ligation of the GMP-140 receptor; 2) Determine the molecular mechanism(s) of GMP-140 potentiation of PAF-stimulated adhesion; 3) Characterize the alterations in PMN functional responses other than adhesion and aggregation that occur as a result of ligating the GMP-140 receptor; 4) Characterize the ability of neonatal PMNs to respond to mediators of adhesion expressed on activated ECs. The information obtained in the first three specific objectives will be applied to the last specific objective. By elucidating the normal EC-PMN adhesive mechanisms, new therapeutic strategies for treating diseases involving defective or unregulated PMN adhesion to EC may be fashioned. In addition, the work proposed will form the basis for a program that will lead to my development as a biomedical investigator.