Intestinal Inflammation: Signaling proteins and the rate of PMN transmigration

描述（由申请人提供）：胃肠道粘膜中的中性粒细胞（PMN）迁移是宿主防御和炎症性肠病（IBD）等病理生理过程的核心组成部分。虽然许多研究都集中在细胞粘附水平上确定PMN迁移调节的事件，但在炎症反应期间，用于调节PMN通过肠粘膜迁移速率的事件却知之甚少。我们小组的研究已经证明了上皮和PMN表达的膜蛋白的重要贡献，这些膜蛋白在连接后启动信号，对PMN转运的动力学有深远的影响。本研究将重点关注被称为CD47-SIRPalpha的受体配体对和一类被称为蛋白酶激活受体（PARs）的蛋白质，它们在肠黏膜和白细胞中差异表达，并通过对PMN和上皮细胞的不同作用调节PMN转运速率。我们已经观察到，迁移的PMN暴露于肠道来源的微生物产物对迁移具有深远的影响，这可能部分与CD47介导的信号传导有关，部分与PMN通过PARs刺激上皮通透性的改变有关。我们的总体目标是了解CD47， SIRP和PARs如何在结构和功能基础上调节PMN在肠道中的转运的机制。为了实现这一目标，我们将采用体外方法与小鼠急性结肠炎模型进行研究，以确定肠上皮和PMN表达CD47的贡献，以及与TLRs的潜在串扰对PMN经上皮迁移率的影响。确定SIRPalpha中介导配体结合/蛋白质相互作用的结构元件，并通过PARs研究PMN-上皮信号在调节PMN跨肠上皮迁移速率中的作用。了解调节PMN跨上皮迁移速率的基本机制可能为粘膜的病理生理学提供线索！IBD等疾病有助于开发新的治疗策略，旨在减少与这些疾病相关的渗透性增强和粘膜损伤。

DESCRIPTION (provided by applicant): Neutrophil (PMN) migration in the gastrointestinal mucosa is a central component of both host defense and pathophysiologic processes such as inflammatory bowel disease (IBD). While many studies have focused on defining events involved in the regulation of PMN migration at the level of cell adhesion, events that serve to regulate the rate with which PMN migrate through intestinal mucosa during the inflammatory response are poorly understood. Studies from our group have demonstrated important contributions from epithelial and PMN expressed membrane proteins which, upon ligation, initiate signals that have profound effects on the kinetics on PMN transmigration. This proposal will focus on a receptor-ligand pair termed CD47-SIRPalpha and a class of proteins termed protease activated receptors (PARs) that are differentially expressed in the intestinal mucosa and on leukocytes and modulate the rate of PMN transmigration through distinct effects on PMN and epithelial cells. We have observed that exposure of migrating PMN to gut-derived microbial products have profound effects on transmigration that may be linked in part to CD47 mediated signaling and in part to PMN stimulated alterations in epithelial permeability through PARs. Our overall goal is to understand the mechanisms of how CD47, SIRP and PARs regulate PMN transmigration in the gut on a structural and functional basis. To achieve this goal we will perform studies employing in vitro methods in concert with murine models of acute colitis to define the contribution(s) of intestinal epithelial and PMN expressed CD47 and potential crosstalk with TLRs on the rate of PMN transepithelial migration, determine structural elements in SIRPalpha that mediate ligand binding/ protein interactions and investigate the role of PMN-epithelial signaling through PARs in regulating the rate of PMN migration across intestinal epithelium. Understanding basic mechanisms regulating the rate of PMN migration across epithelia may provide clues to the pathophysiology of mucosa! diseases such as IBD and aid in the development of new therapeutic strategies aimed at diminishing enhanced permeability and mucosal injury associated with these conditions.