MECHANISMS OF PMN ACTIVATION MEDIATED BY GMP-140 AND PAF

中性粒细胞（PMNs）从血流中迁移到 炎症部位是粘附到血管内皮细胞（EC）。 一个 炎症部位PMN-EC粘附的损伤导致复发性 和严重感染，如发生在具有遗传缺陷的个体中， 中性粒细胞粘附蛋白，并在新生儿，其中缺陷是穷人 表征了 或者，PMN粘附于EC可能导致血管性炎症。 损伤如局部或整体缺血-再灌注损伤、坏死性 小肠结肠炎或透明膜病伴继发性支气管肺炎 发育不良 这种粘附相互作用有两种机制： 依赖于液相趋化因子对PMN的激活; 2） 依赖于由激活的EC表达的促粘附分子。 越 生理相关机制可能是依赖于EC激活的机制 因为它以空间特异性的方式靶向PMNs。 刺激EC 快速作用的激动剂在其表面上表达两种前粘附分子， 血小板颗粒膜蛋白140和血小板活化因子 （PAF）。 EC表面表达的PAF与其PMN受体结合， 激活PMN并上调CD 11/CD 18整合素， 粘连 粘附机制涉及一个新的例子， 细胞-细胞相互作用，其中细胞相关的PAF作为信号， 激活PMN。 GMP-140最近才被确定为促粘附剂 在快速激活的EC上表达的分子。 初步数据表明 其表达对于PAF介导的结合的发生是必需的， GMP-140增强PAF刺激的CD 11/CD 18依赖性粘附。 然而，GMP-140对PMN的作用似乎是复杂的，它可能 抑制PMN-CD 11/CD 18上调和其它活化反应 一些条件。 GMP-140与其结合的功能后果 PMN上的受体尚未确定。 这些改变很重要 考虑到GMP-140可能在PMNs初始粘附于 炎症部位的内皮细胞。 本项目有4个具体 目的：1）探讨中性粒细胞（PMN）粘附分子CD 11/CD 18的变化 由GMP-140受体的连接引起的反应; 2）确定 GMP-140增强PAF刺激粘附的分子机制; 3)描述PMN功能反应的变化， 由于连接GMP-140而发生的粘附和聚集 受体; 4）表征新生儿PMNs响应 粘附介质在活化的EC上表达。 获得的信息 在前三个具体目标将适用于最后一个具体 objective. 通过阐明正常的EC-PMN粘附机制， 用于治疗涉及缺陷性或 可能形成不受调节的PMN对EC的粘附。 此外，工作 提出的将形成一个计划的基础，这将导致我的发展 作为一名生物医学调查员

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.