Intestinal Inflammation Induced by Pathogens

描述（由申请方提供）：炎症性肠病（IBD），包括克罗恩病（CD）和溃疡性结肠炎（UC），是一种慢性疾病，其特征为中性粒细胞（PMN）明显浸润至结肠粘膜病变中，伴有上皮细胞坏死和溃疡。疾病活动和患者症状也与粘膜和表面上皮内PMN浸润的组织学发现相关。在由鼠伤寒沙门氏菌（沙门氏菌病）引起的胃肠炎急性期，也发生了同样的组织学事件，即大量的中性粒细胞经上皮迁移。因此，了解病原体引起的肠道活动性炎症将作为一个重要的模型，以提供有关IBD活动性炎症的有价值的信息。利用肠道致病菌S.鼠伤寒沙门氏菌作为一种工具，以调查机制的基础上，PMN招聘整个肠上皮细胞，我们已经证明了一个新的和核心的作用，类花生肝氧素A3（HXA 3）。HXA 3是由12-脂氧合酶（12-LO）途径的酶促作用形成的花生四烯酸衍生物。这一观察结果揭示了以前未探索的现象，机械地解释了肠道炎症活动状态的主要组织病理学特征。此外，我们最近发现，HXA 3是通过位于肠上皮细胞顶端表面的外排转运系统分泌的，该系统涉及ABC转运蛋白MRP 2。我们还发现，肠道炎症的诱导对应于MRP 2的顶端表达的显著上调。MRP 2的这种上调在IBD的慢性鼠模型和来自活动性CD或UC患者的人肠活检组织中进一步体内证实。因此，该项目的主要目标是了解HXA 3合成的分子机制（具体目标1），以及确定HXA 3的生产是如何调节的（具体目标2）。为了实现这些目标，我们计划使用互补的体外和体内模型结合最先进的细胞，分子和生物化学技术。我们假设，了解基于HXA 3/MRP 2的信号传导，指导PMN在肠上皮中的运动，将导致重要的治疗方法的发展，旨在帮助控制感染性，过敏性和特发性（IBD）结肠炎患者的炎症事件。

DESCRIPTION (provided by applicant): Inflammatory bowel diseases (IBDs) including Crohn's disease (CD) and ulcerative colitis (UC) are chronic diseases characterized by a pronounced infiltration of neutrophils (PMNs) into colonic mucosal lesions, accompanied by epithelial cell necrosis and ulceration. Disease activity and patient symptoms also correlate with the histologic finding of PMN infiltrates within the mucosa and surface epithelium. This same histological event of massive transepithelial migration of PMNs occurs in the acute phase of gastroenteritis induced by Salmonella enterica serovar Typhimurium (salmonellosis). Thus, insight into pathogen elicited active inflammation of the intestine will serve as an important model to provide valuable information relating to active inflammation in IBD. Using the enteric pathogen S. typhimurium as a tool to investigate mechanisms underlying PMN recruitment across the intestinal epithelia, we have demonstrated a novel and central role for the eicosanoid hepoxilin A3 (HXA3). HXA3 is a derivative of arachidonic acid formed from the enzymatic action of the 12-lipoxygenase (12-LO) pathway. This observation has unlocked a previous unexplored phenomenon that mechanistically explains a primary histopathologic feature of active states of intestinal inflammation. Moreover, we have recently shown that HXA3 is secreted through an efflux transport system located at the apical surface of the intestinal epithelia that involves the ABC transporter MRP2. We also revealed that induction of intestinal inflammation corresponds to a profound up-regulation of the apical expression of MRP2. Such up-regulation of MRP2 was further demonstrated in vivo in chronic murine models of IBD and human intestinal biopsy tissues from patients with active CD or UC. Thus, the primary objectives of this project are to understand the molecular mechanisms underlying HXA3 synthesis (Specific Aim 1), as well as to determine how HXA3 production is regulated (Specific Aim 2). To accomplish these aims we plan to use a combination of complementary in vitro and in vivo models coupled with state of the art cellular, molecular, and biochemical techniques. We hypothesize that understanding HXA3/MRP2 based signaling, which directs the movement of PMNs across the intestinal epithelium, will lead to the development of important therapeutics designed to help control this inflammatory event in patients with infectious, allergic, and idiopathic (IBD) colitis.