Effect of Neutrophil Priming on Chemotaxis and Signaling

多形核白细胞(PMN)是一种固有的可运动的细胞类型，可以被引导向上移动 化学吸引剂梯度。趋化运动是中性粒细胞在组织损伤部位聚集所必需的 或感染，然而，提供导航信号的机制需要给这些 人们对细胞的理解还不完全。白色念珠菌是医院感染的第四大原因， 手术后、创伤和免疫抑制的患者风险最高。I_-葡聚糖，其主要成分 酵母菌细胞壁，被阐述到系统性念珠菌病患者的血液中，尽管 I_-葡聚糖在本病的病理生物学中的作用尚不清楚。这个实验室的最新发现表明，我-- 葡聚糖，将PMN的随机迁移转化为定向迁移。这种转换是通过识别13- 葡聚糖由白细胞132整合素CR3(CD11 b/CD18)调节，是一种先前未知的13-葡聚糖对 中性粒细胞功能。我们工作的长期目标是了解13-14对宿主防御的影响- 在系统性真菌感染过程中的葡聚糖。当前提案的重点是确定 CR3识别13-葡聚糖改变中性粒细胞功能的机制。我将在AIM进行实验 研究几个细胞内信号通路的作用，根据我们目前的发现，这些通路是 假设介导中性粒细胞在13-葡聚糖上迁移的趋化能力增强- 补充矩阵。《特殊目的II》将应用一种具有良好特征的伤口模型来演示 _-葡聚糖对宿主中性粒细胞对损伤的反应能力。体外研究结果确定了 β-葡聚糖激活CR3调节131家族整合素的功能。受伤的模型会 确定13-葡聚糖和/或系统性念珠菌病是否类似地改变131整合素的功能 调解中性粒细胞进入损伤部位。最后，几种促炎介质(内毒素、免疫 尿激酶型纤溶酶原激活剂)与糖基磷脂酰肌醇(GPI)连接的受体结合 (CD14、CD16、CD87)，这些信号转而依赖CR3进行细胞内信号传递。SPARTIC AIM III将测试 一种新的整合素串扰途径将GPL连接的受体从CR3分子中分离出来的假设。 由于13-葡聚糖和GPL连接的受体共享一个共同的CR3结合部位，GPL连接的解离 CR3受体可同时增加可与13-葡聚糖结合的CR3分子的数量 并削弱对GPL连接受体的特异性配体的反应。拟议的研究将进一步阐明 I-葡聚糖启动中性粒细胞作为全身真菌成分的作用机制 作为一种生物反应调节剂，具有治疗多菌败血症的潜力。

Polymorphonuclear leukocytes (PMN) are an inherently motile cell type which can be directed to move up a chemoattractant gradient. Chemotactic movement is essential for PMN accumulation at sites of tissue injury or infection, however, mechanisms which provide the navigational signals needed to give direction to these cells are incompletely understood. Candida albicans is the fourth leading cause of nosocomial infections with post-surgical, trauma and immunosuppressed patients being at highest risk. I_-glucan, a major component of the yeast cell wall, is elaborated into the bloodstream of patients with systemiccandidiasis although the role of I_-glucan in the pathobiology of the disease is not clear. Recent findings from this laboratory have shown I_- glucan, converts PMN migration from random to directed. The conversion is mediated by recognition of 13- glucan by the leukocyte 132integrin CR3 (CD11 b/CD18) and is a previously unrecognized effect of 13-glucan on neutrophil function. The long term goal of our work is to understand how host defenses are affected by 13- glucan during the course of systemic fungal infections. The focus of the current proposal is to determine the mechanisms through which 13-glucan recognition by CR3 alters neutrophil function. Experiments in Aim I will investigate the role of several intracellular signalling pathways that, based on our current findings, are hypothesized to mediate the increased chemotactic capacity of neutrophils migrating on 13-glucan- supplemented matrix. Specific Aim II will apply a well-characterized wound model to demonstrate the effect of _-glucan on the ability of the host neutrophils to respond to injury. In vitro findings have determined that activation of CR3 by _-glucan regulates the function of integrins of the 131 family. The wound model will determine whether 13-glucan and/or systemic candidiasis similarly alters the function of 131 integrins in mediating PMN entry into a site of injury. Finally, several proinflammatory mediators (LPS, immune complexes, urokinase plasminogen activator) bind to glycosylphosphatidylinositol (GPI)-Iinked receptors (CD14, CD16, CD87) which in turn rely on CR3 for intracellular signalling. Specific Aim III will test the hypothesis that a novel pathway of _1 integrin crosstalk dissociates GPl-linked receptors from CR3 molecules. Since 13-glucan and GPl-linked receptors share a common CR3 binding site, dissociation of GPl-linked receptor from CR3 would simultaneously increase the number of CR3 molecules available for 13-glucan binding and blunt the response to ligands specific for GPl-linked receptors. The proposed studies will further elucidate the mechanism of action through which I_-glucan primes neutrophils both as a component of systemic fungal infections and as a biological response modifier with therapeutic potential for treating polymicrobial sepsis.