Epithelial control of Neutrophil Activation

描述（由申请人提供）：虽然是先天免疫的重要分支，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中前进，穿过淋巴结，并穿过上皮屏障，它们经历了渐进的活化阶段。因此，当中性粒细胞移动通过不同的组织区室时，与驻留细胞和分子的特异性相互作用调节和限制中性粒细胞的活化是合理的。支持这一概念的数据表明，损伤肺中中性粒细胞的跨上皮迁移和活化在缺乏基质溶解素（一种上皮产生的基质金属蛋白酶（MMP））的小鼠中被阻断。这些研究还表明，CXC趋化因子KC（一种有效的急性期中性粒细胞化学引诱物）与syndecan-1（一种肺上皮细胞基底表面上的跨膜硫酸乙酰肝素蛋白聚糖）的糖胺聚糖（GAG）链结合。损伤后，基质溶解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，重要的是，激活，从而防止在上皮细胞表面的破坏性氧化爆发。相反，与可溶性KC/syndecan-1复合物的相互作用促进中性粒细胞活化，理想地在离粘膜层更安全的距离处。对于目标1，将详细评估无基质溶素和无多配体蛋白聚糖-1对肺损伤和感染的响应，并且将使用高分辨率成像和嗜中性粒细胞介导的氧化的标志物来定位在这些小鼠染色中中性粒细胞活化停止的位置和阶段。对于目标2，将使用转基因小鼠、转染的细胞和纯化的试剂来测试中性粒细胞对固定化或细胞固定的与可溶性KC/多配体蛋白聚糖-1复合物的不同响应的想法。对于目标3，KC和多配体蛋白聚糖-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，进而阻断嗜中性粒细胞活化。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新的基本机制，这是炎症反应的关键早期步骤。这项工作的知识可能提供一种有效的策略，以限制炎症相关的损害，不仅在肺，但在所有组织。

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.