Epithelial control of Neutrophil Activation

描述（由申请人提供）：虽然是先天免疫的重要组成部分，但活化的中性粒细胞对与肺损伤和炎症相关的组织损伤有很大贡献。随着中性粒细胞从脉管系统出发，穿过间质，穿过上皮屏障，它们经历了渐进的激活阶段。因此，当中性粒细胞穿过不同的组织室时，与常驻细胞和分子的特定相互作用调节和限制中性粒细胞的激活是合理的。支持这一概念的数据表明，在缺乏基质溶素（一种上皮产生的基质金属蛋白酶（MMP））的小鼠中，受损肺的经上皮迁移和中性粒细胞的激活被阻断。这些研究还表明，CXC趋化因子KC是一种有效的急性期中性粒细胞趋化剂，与syndecan-1的糖胺聚糖（GAG）链结合，syndecan-1是肺上皮细胞基表面的一种跨膜硫酸肝素蛋白聚糖。损伤后，基质溶素从上皮细胞表面脱落这些复合物。该项目的中心假设是，与细胞结合的KC/syndecan-1复合物的相互作用限制了中性粒细胞的运动，更重要的是，抑制了活化，从而防止了上皮细胞表面的破坏性氧化破裂。相反，与可溶性KC/syndecan-1复合物相互作用可促进中性粒细胞活化，理想情况下，中性粒细胞活化距离粘膜层较安全。对于Aim 1，将详细评估母溶素-null和syndecan-1-null对肺损伤和感染的反应，并将使用高分辨率成像和中性粒细胞介导的氧化标记来定位这些小鼠染色中中性粒细胞激活停止的位置和阶段。在Aim 2中，将使用转基因小鼠、转染细胞和纯化试剂来测试中性粒细胞对固定化或细胞固定与可溶性KC/syndecan-1复合物的反应不同。对于Aim 3， KC和syndecan-1 GAG链之间的相互作用将被映射，以设计试剂来阻断这种相互作用，进而阻断中性粒细胞的激活。与公共卫生问题的相关性：这些研究将描述中性粒细胞活化的一种新的、基本的机制，这是炎症反应的一个关键的早期步骤。从这项工作中获得的知识可能提供一种有效的策略来限制炎症相关的损害，不仅在肺部，而且在所有组织中。

DESCRIPTION (provided by applicant): Although an essential arm of innate immunity, activated neutrophils contribute greatly to the tissue damage associated with lung injury and inflammation. As neutrophils advance from the vasculature, through the interstitium, and across the epithelial barrier, the go through progressive stages of activation. Thus, it is reasonable that specific interactions with resident cells and molecules regulate and constrain the activation of neutrophils as these granulocytes move through different tissue compartments. Data in support of this concept demonstrate that the transepithelial migration and activation of neutrophils in injured lung are blocked in mice lacking matrilysin, an epithelial-produced matrix metalloproteinase (MMP). These studies also showed that the CXC chemokine KC, a potent, acute-phase neutrophil chemoattractant, is bound to the glycosaminoglycan (GAG) chains of syndecan-1, a transmembrane heparan sulfate proteoglycan on the basal surface of lung epithelial cells. Following injury, matrilysin sheds these complexes from the epithelial cell surface. The central hypothesis of this project is that interaction with cell-bound KC/syndecan-1 complexes constrains neutrophil movement and, importantly, activation, thereby preventing a damaging oxidative burst at the epithelial cell surface. In contrast, interacting with soluble KC/syndecan-1 complexes promotes neutrophil activation, ideally at a safer distance from the mucosal layer. For Aim 1, the response of matrilysin-null and syndecan-1-null to lung injury and infection will be assessed in detail, and high resolution imaging and markers of neutrophil-mediated oxidation will be used localized where and what stage neutrophil activation is halted in these mouse stains. For Aim 2, transgenic mice, transfected cells, and purified reagents will be used to test the idea that neutrophils respond differently to immobilized or cell-fixed versus soluble KC/syndecan-1 complexes. For Aim 3, the interaction between KC and syndecan-1 GAG chains will be mapped to design reagents to block this interaction and, in turn, neutrophil activation. Relevance to Public Health Concerns: These studies will characterize a novel, fundamental mechanism of neutrophil activation, a key, early step of an inflammatory reaction. Knowledge from this work may provide an effective strategy to limit inflammation-associated damage not only in lung, but in all tissues.