Immunomodulation in infectious diarrhea

感染性腹泻的免疫调节

• 批准号: 6731993
• 负责人: JAN-MICHAEL AXEL KLAPPROTH
• 金额: $ 12.66万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6731993
• 关键词: Clostridium; Escherichia coli; T cell receptor; T lymphocyte; bacterial toxins; clinical research; diarrhea; gastrointestinal infection; gene mutation; genetically modified animals; glycosyltransferase; guanine nucleotide binding protein; human subject; immunosuppression; interferon gamma; interleukin 2; interleukin 4; laboratory mouse; leukocyte activation /transformation; mucosal immunity; site directed mutagenesis

DESCRIPTION (provided by applicant): The goal of the principal investigator is to continue to develop intellectual, technical, and analytical skills to become an independently funded physician-scientist investigator in microbial pathogenesis, examining the effect of bacterial products on the immune system. The program to achieve this goal will consist of additional didactic and laboratory training in basic immunology, lymphocyte signal transduction, and microbial and molecular genetics. Bacterial immunomodulatory products are of utmost importance in infectious diseases and their prevention. For example, C. difficile toxin A and B are implicated in the development of pseudomembranous enterocolitis, and cholera toxin functions as an adjuvant in oral immunization. In this proposal we will continue to characterize a novel toxin from Enteropathogenic E. coli (EPEC), resulting in marked inhibition of T cell activation. The inhibitory gene, lifA (lymphocyte inhibitory activity), encodes for a protein with the putative size of 366kDa. The lifA gene product, lymphostatin, bears significant similarity to the N-terminus of large Clostridial cytotoxins, encoding for a glucosyltransferase motif, which is critical for their specific activity. Similar immunosuppressive genes and biological activity have been identified in related bacteria, including other EPEC strains, Enterohemorrhagic E. coli, and the mouse pathogen C. rodentium. Our hypothesis is that the glucosyltransferase motif in lymphostatin is critical for the observed immunosuppression, leading to inhibition of defined lymphocyte subpopulations of the adaptive immune response and allowing firm establishment of enteric Gram negative infection. To test the hypothesis, we propose: Aim 1: To identify the co-substrate and target molecule(s) in lymphocytes exposed to lymphostatin. Aim 2: To investigate intracellular activation pathways in defined lymphocyte populations affected by lymphostatin, resulting in suppression of IL-2, IL-4, and IFN-gamma expression. Aim 3: To investigate whether lymphostatin suppresses the mucosal adaptive immune response and firmly establishes C. rodentium enteric infection in vivo. The proposed research project will contribute to the understanding of immune mechanisms involved in the pathogenesis of chronic infectious diarrhea and gastrointestinal inflammation as seen in Crohn's disease and ulcerative colitis.

描述（由申请人提供）： 主要研究者的目标是继续发展智力，技术和分析技能，成为微生物发病机制的独立资助的医生-科学家调查员，检查细菌产品对免疫系统的影响。实现这一目标的计划将包括基础免疫学，淋巴细胞信号转导，微生物和分子遗传学的额外教学和实验室培训。 细菌免疫调节产品在感染性疾病及其预防中至关重要。 例如，C.艰难梭菌毒素A和B与伪膜性小肠结肠炎的发展有关，霍乱毒素在口服免疫中起佐剂的作用。 在这个建议中，我们将继续描述一种新的肠致病性大肠杆菌毒素。大肠杆菌（EPEC）中，导致显著抑制T细胞活化。抑制基因lifA（淋巴细胞抑制活性）编码一个推定大小为366 kDa的蛋白质。lifA基因产物淋巴抑制素与大梭菌细胞毒素的N-末端具有显著的相似性，编码葡糖基转移酶基序，这对其特异性活性至关重要。相似的免疫抑制基因和生物活性已在相关细菌中鉴定，包括其他EPEC菌株，肠出血性大肠杆菌。coli和小鼠病原C.啮齿动物。 我们的假设是，淋巴抑制素中的葡萄糖基转移酶基序对于观察到的免疫抑制是至关重要的，导致抑制适应性免疫应答的限定淋巴细胞亚群，并允许牢固建立肠道革兰氏阴性感染。为了验证这一假设，我们提出：目的1：鉴定暴露于淋巴抑制素的淋巴细胞中的共底物和靶分子。目标二：研究受淋巴抑制素影响的特定淋巴细胞群的细胞内活化途径，导致IL-2、IL-4和IFN-γ表达抑制。目的3：研究淋巴抑制素是否抑制粘膜适应性免疫反应，并确定C。啮齿类肠道感染。 拟议的研究项目将有助于了解慢性感染性腹泻和胃肠道炎症的发病机制，如克罗恩病和溃疡性结肠炎。