Intestinal Inflammation orchestrated by pathogens

描述（由申请人提供）：最近从许多炎症性肠病（IBD）模型中积累的数据继续强化了定义肠道细菌对肠道炎症的贡献的重要性。沙门氏菌病以及与患者症状相关的IBD的病理特征是中性粒细胞（PMN）穿过肠上皮并进入腔隙形成隐窝脓肿。我们已经证明，PMN穿过上皮的最后一步是由核因子kappaB （NF-kappaB）引导的，这是一种可溶性生物活性的非依赖性释放，从上皮的顶端表面释放，以前被称为PEEC（病原体诱导的上皮化学引诱剂），我们最近确定为类eicosinoid hepoxilin A3 （hepA3）。我们研究了PEEC/hepA3从肠上皮释放的机制，发现鼠伤寒沙门氏菌III型分泌的效应蛋白SipA参与了这一过程。SipA激活了一种新的脂质信号级联，其中蛋白激酶C （pkc - α）被激活，导致hepA3的分泌。我们的总体假设是，导致hepA3分泌的信号通路不仅在病原体诱导的炎症（即鼠伤寒沙门氏菌）中很重要，而且在肠道炎症期间该通路可能失调。了解细菌诱导上皮细胞协调这种反应的机制，可能为了解IBD等特发性疾病中事件发生的机制提供关键的见解。因此，本研究的长期目标是了解SipA调控肠上皮细胞hepA3释放的分子机制。特异性Aim 1旨在表征鼠伤寒沙门氏菌效应分子SipA与肠上皮细胞之间发生的分子相互作用，从而激活导致hepA3分泌的信号转导通路。本研究的目的是：(i)确定SipA的功能域，该功能域调节导致hepA3释放的信号事件，以及（ii）鉴定和功能表征一个假定的SipA受体。特异性Aim 2旨在识别导致hepA3顶端释放的信号转导事件。因此，我们计划(i)绘制导致hepA3产生的信号转导级联图，（ii）检查hepA3外排的分子机制，以及（iii）检查肠道炎症体内模型中信号转导事件的重要性。

DESCRIPTION (provided by applicant): Recent data accumulated from numerous models of inflammatory bowel disease (IBD) continue to reinforce the importance of defining the contribution of luminal bacteria to intestinal inflammation. The pathognomonic feature of salmonellosis, as well as IBD, which is correlated with patient symptomatology, is the transepithelial migration of neutrophils (PMN) across intestinal epithelia and into the luminal space to form crypt abscesses. We have shown that this final step of PMN movement across the epithelium to be directed by nuclear factor kappaB (NF-kappaB)-independent release of a soluble bioactivity from the apical surface of the epithelium - previously termed PEEC (pathogen-elicited epithelial chemoattractant), which we have recently identified as the eicosinoid hepoxilin A3 (hepA3). Our studies investigating the mechanism underlying the release of PEEC/hepA3 from intestinal epithelia have revealed the involvement of the Salmonella typhimurium type III secreted effector protein SipA. SipA activates a novel lipid signaling cascade whereby protein kinase C (PKC-alpha) is activated resulting in secretion of hepA3. Our overall hypothesis is that the signaling pathway resulting in the secretion of hepA3 is important not only during pathogen-induced inflammation (i.e. S. typhimurium) but that this pathway may be dis-regulated during intestinal inflammation. Understanding the mechanism by which epithelial cells are induced by bacteria to orchestrate this response may provide key mechanistic insights into how events occur in an idiopathic disease such as IBD. Thus, the long-term objective of this proposal is to understand the molecular mechanisms underlying SipA regulation of hepA3 release by the intestinal epithelia. Specific Aim 1 is designed to characterize the molecular interaction that occurs between the S. typhimurium effector molecule, SipA, and the intestinal epithelial cell that triggers the activation of the signal transduction pathway leading to hepA3 secretion. The goals of this aim are to (i) determine the functional domain of SipA that regulates the signaling event leading to hepA3 release, and (ii) to identify and functionally characterize a putative SipA receptor. Specific Aim 2 is designed to identify the signal transduction events, which lead to the apical release of hepA3. Thus, we plan to (i) map the signal transduction cascade leading to hepA3 production, (ii) examine the molecular mechanism of hepA3 efflux, and (iii) examine the importance of the signaling events in vivo models of intestinal inflammation.