CORTICOTROPHIN RELEASING FACTOR IN INTESTINAL INFLAMMATI

众所周知，神经肽是肠道炎症反应的重要组成部分。在过去的资助期中产生的结果首次表明，在肠道中局部释放的41个氨基酸多肽促肾上腺皮质激素释放激素(CRH)是不同原因的急性肠炎的有效促炎介质。我们还观察到人结肠上皮细胞具有CRH受体，这些受体在体内和体外感染艰难梭菌毒素A或促炎细胞因子后，在肠道炎症过程中上调。我们的总体假设是，外周CRH和CRN相关多肽urocortins通过与肠细胞和巨噬细胞上的特定CRH受体结合来增强急性结肠炎。CRH和尿皮质激素依赖的促炎转录因子和MAP-K相关途径的激活导致促炎细胞因子的释放，从而启动增强肠道炎症的过程。在目标1中，我们将阐明核因子-kappaB/kappaB系统和MAP激酶在CRH受体介导的人结肠上皮细胞和巨噬细胞的促炎信号中的作用。与Ciaran Kelly博士合作，我们还将在体外和体内检测益生菌在毒素A和促炎细胞因子诱导的CRH受体表达增加中的作用。Aim 2的研究将确定CRH家族多肽(urocortin I、II和III)在野生型和CRH受体缺陷小鼠的急性回肠炎中的作用，以及 与Allan Walker博士(异种移植核心)在人类肠道异种移植中的合作。我们还将与Beth McCormick博士合作，评估其他常见的胃肠道细菌和细菌产物(沙门氏菌、志贺氏菌、脂多糖)对体内和体外人类结肠细胞CRH多肽家族和CRH受体表达的影响。目的3研究促炎症细胞因子和艰难梭菌毒素A对肠上皮细胞和巨噬细胞CRH受体调节的机制(S)，以及CRH和CRH相关多肽在体外(巨噬细胞和结肠细胞)和体内对CRH+/+和CRH-/-小鼠CRH受体表达的调节作用。这些研究结果将有助于我们剖析促肾上腺皮质激素释放激素家族多肽及其受体参与肠道炎症的机制(S)。

It is well accepted that neuropeptides are important components of the intestinal inflammatory response. Results generated during the past funding period demonstrated for the first time that the 41 aa peptide corticotropin-releasing hormone (CRH), released locally in the gut, is a potent promflammatory mediator of acute intestinal inflammation of different etiologies. We also made the novel observation that human colonocytes bear receptors for CRH, and these receptors are upregulated during intestinal inflammation in vivo and in vitro after exposure to C. difficile toxin A or proinflamrmtory cytokines. Our overall hypothesis is that peripheral CRH and the CRN-related peptides urocortins augment acute colonic inflammation by binding to specific CRH receptors on enterocytes and macrophages. CRH and urocortin-ddpendent activation of proinflammatory transcription factors and MAP-kinase - related pathways lead to the release of proinflammatory cytokines thereby initiating of augmenting intestinal inflammation. In aim 1 we will elucidate the participation of the NF-kappaB/kappaB system and MAP kinases in CRH receptor-mediated proinflammatory signalling in human colonic epithelial cells and macrophages. In collaboration with Dr. Ciaran Kelly we will also examine the effect of probiotics in toxin A and proinflammatory cytokines - induced increased CRH receptor expression in vitro and in vivo. Studies in aim 2 will determine the role of the CRH family of peptides (urocortin I, II, and III) in acute intestinal inflammation in mouse ileal loops in wild type and CRH receptor deficient mice and, in collaboration with Dr. Allan Walker (xenograft core), in human intestinal xenografts. In collaboration with Dr. Beth McCormick we will also assess the effect of other common GI bacteria and bacterial products (Salmonella, Shigella, LPS) on the CRH peptide family and CRH receptor expression in human colonocytes in vivo and in vitro. Aim 3 will examine the mechanism(s) of CRH receptor regulation in intestinal epithelial cells and macrophages by proinflammatory cytokines and C. difficile toxin A. We will also study whether CRH and CRH-related peptides themselves regulate CRH receptor expression in vitro (macrophages and colonocytes) and in vivo in CRH +/+ and CRH -/- mice. Results from the proposed studies will help us dissect the mechamsm(s) by which CRH family of peptides and their receptors participate in intestinal inflammation.