Epithelial control of Neutrophil Activation

描述(申请人提供)：尽管中性粒细胞是先天免疫的重要组成部分，但它对肺损伤和炎症相关的组织损伤有很大的作用。随着中性粒细胞从血管系统进入，穿过间质，穿过上皮屏障，中性粒细胞经历了渐进的激活阶段。因此，当中性粒细胞在不同的组织隔间移动时，与驻留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，在缺乏基质溶素的小鼠中，损伤肺中中性粒细胞的跨上皮迁移和激活受到阻止。基质溶素是一种上皮产生的基质金属蛋白酶(MMPs)。这些研究还表明，CXC趋化因子KC是一种有效的急性时相中性粒细胞趋化物质，与Syndecan-1的糖胺多糖链(GAG)结合，Syndecan-1是一种位于肺上皮细胞基底面的跨膜硫酸乙酰肝素蛋白多糖。损伤后，基质溶素将这些复合体从上皮细胞表面脱落。该项目的中心假设是，与细胞结合的KC/Syndecan-1复合体的相互作用限制了中性粒细胞的运动，更重要的是，限制了中性粒细胞的激活，从而防止了上皮细胞表面的破坏性氧化爆发。相反，与可溶性KC/Syndecan-1复合体相互作用促进中性粒细胞激活，理想情况下与粘膜层保持较安全的距离。对于目标1，将详细评估Matrilysin-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的中性粒细胞激活在哪里和什么阶段停止。对于目标2，将使用转基因小鼠、转基因细胞和纯化试剂来测试中性粒细胞对固定化或细胞固定化的KC/syndecan-1复合体的反应不同于可溶性KC/syndecan-1复合体的想法。对于目标3，KC和Syndecan-1 Gag链之间的相互作用将被映射到设计试剂来阻止这种相互作用，进而阻止中性粒细胞的激活。与公共卫生问题相关：这些研究将描述一种新的、中性粒细胞激活的基本机制，这是炎症反应的关键早期步骤。来自这项工作的知识可能提供一种有效的策略，不仅在肺部，而且在所有组织中限制与炎症相关的损害。

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.