Anti-inflammatory effects of colitis-induced changes in commensal gut microbes

描述（由申请人提供）：人类炎症性肠病（IBD），包括克罗恩病和溃疡性结肠炎，是终身的，潜在的使肠道衰弱的疾病，被认为是由于对通常定植在肠道中的正常细菌的过度侵袭性免疫反应。目前的治疗方法侧重于抑制人的免疫系统，这可能导致癌症和感染等并发症。这项研究的总体目标是更好地了解细菌如何促进IBD的发展，以便开发新的药物，专门针对肠道微生物，对人体的风险最小。最近来自IBD动物模型的数据表明，炎症会导致肠道细菌增加小热休克蛋白的表达，从而减轻宿主的炎症。这些热休克蛋白的抗炎特性是否也在其他细菌应激反应系统中观察到尚不清楚，是这些研究的主题。识别和了解具有抗炎特性的细菌应激反应系统可以通过靶向多种细菌应激反应途径的主要调节因子来开发治疗IBD的新型药物。初步数据表明，结肠中的非致病性大肠杆菌在结肠炎期间也上调抗酸基因gadA和gadB的表达，这些基因抑制细菌进入肠道组织，阻止巨噬细胞杀死大肠杆菌。拟开展的研究旨在：1)确定大肠杆菌gadAB表达对实验性IBD发展的影响；2)确定大肠杆菌gadAB表达抑制细菌跨肠上皮细胞运动的机制；3)研究大肠杆菌gadAB如何促进巨噬细胞内细菌存活和抗原加工。白细胞介素-10敲除小鼠，当被某些细菌定植时发生自发性结肠炎，将选择性地定植基因改变的非致病性大肠杆菌菌株。大肠杆菌感染T84肠上皮细胞的体外研究

DESCRIPTION (provided by applicant): Human inflammatory bowel diseases (IBD's), including Crohn's disease and ulcerative colitis, are life-long, potentially debilitating intestina disorders thought to be due to overly-aggressive immune responses to normal bacteria that typically colonize the intestines. Current treatments focus on suppressing a person's immune system, which can lead to complications such as cancer and infections. The overall goal of this research is to better understand how bacteria contribute to the development of IBD's so that new medications can be developed that specifically target the intestinal microbes with minimal risk to the person. Recent data from animal models of IBD's suggest that inflammation causes intestinal bacteria to increase expression of small heat shock proteins, which in turn attenuate host inflammation. Whether anti-inflammatory properties of these heat shock proteins are also observed in other bacterial stress response systems is unknown and is the subject of these studies. Identifying and understanding the bacterial stress response systems that have anti- inflammatory properties could lead to the development of novel agents to treat IBD's by targeting master regulators of multiple bacterial stress response pathways. Preliminary data suggest that non-pathogenic E. coli in the colon also upregulate expression of acid resistance genes, gadA and gadB, during colitis and that these genes inhibit movement of the bacteria into intestinal tissues and prevent killing of E. coli by macrophages. The proposed studies aim to 1) Determine the effects of E. coli gadAB expression on the development of experimental IBD's, 2) Identify mechanisms by which E. coli gadAB expression inhibits movement of bacteria across intestinal epithelial cells, and 3) Study how E. coli GadAB promote bacterial survival within, and antigen processing by, macrophages. Interleukin-10 knockout mice, which develop spontaneous colitis when colonized by certain bacteria, will be selectively colonized with genetically altered non-pathogenic E. coli strains. In vitro studies of E. coli-infected T84 intestinal epithelial cell monolayers and bone-marrow derived macrophages will help determine mechanisms by which E. coli GadAB affects bacterial translocation and immune system activation. It is anticipated that completion of the proposed studies will: 1) identify novel functions of E. coli GadAB, 2) determine the anti-inflammatory potential of E. coli GadAB in experimental IBD's, 3) increase understanding of how IBD's develop, and 4) lead to future studies of manipulating bacterial stress responses for therapeutic purposes.