Different bacterial species selectively induce TH1 cells

描述(由申请人提供)： 慢性复发性肠炎似乎是由遗传易感个体对共生(非致病)肠道细菌的先天性和获得性免疫反应失调所介导的。我们假设(1)各种非致病共生细菌在遗传易感宿主中诱导不同的疾病表型，这是由于对细菌抗原的区域性限制的黏膜免疫反应或B.肠道不同区域的选择性上皮黏附/侵袭，以及(2)离散数量的粪肠球菌抗原诱导失调的T细胞免疫反应，导致慢性肠炎的诱导和持续。这些假说针对以下具体目标：1.确定粪肠球菌和大肠杆菌单独和联合在同一遗传易感宿主IL-10-/-小鼠中诱导不同疾病表型的机制： A.比较大肠杆菌和粪肠球菌的毒力因素(上皮黏附和侵袭)，发现它们在单相关IL-10-/-小鼠中不同地诱导不同的疾病表型，与从人类克罗恩病患者中分离的已知黏附/侵袭性大肠杆菌(AIEC)菌株，以及从患有结肠炎和WT小鼠的SPF IL-10-/-小鼠中随机分离的共生大肠杆菌和粪肠球菌菌株进行比较。 B.在体内确定与这两种细菌共存的IL-10-/-小鼠中每种细菌对粘膜黏附和侵袭的区域性差异。 C.研究从与大肠杆菌或粪肠球菌单一相关的结肠炎IL-10-/‘-小鼠体内过继转移的CD4+细胞在免疫缺陷小鼠中诱导局部特异性肠炎和可变疾病动力学的能力。2.通过以下方法确定激活单相关IL-10-/-小鼠T细胞的优势粪肠球菌抗原： A.确定在患有结肠炎的粪肠球菌单相关IL-10-/-小鼠的肠系膜淋巴结中诱导CD4+T细胞产生干扰素-γ反应的主要抗原(在通过血清学反应筛选的表达文库中鉴定)。 B.通过截断突变鉴定参与IL-10-/-小鼠免疫激活和随后的肠道炎症持续存在的特定表位(S)。 C.确定重组非致病细菌是否能诱导T细胞介导的结肠炎和十二指肠炎。

DESCRIPTION (provided by applicant): Chronic relapsing intestinal inflammation appears to be mediated by dysregulated innate and acquired immune responses to commensal (nonpathogenic) enteric bacteria in genetically predisposed individuals. We hypothesize that (1) various non-pathogenic commensal bacteria induce distinct disease phenotypes in genetically susceptible hosts due to either regionally restricted mucosal immune responses to bacterial antigens or b. selective epithelial adherence/ invasion in different regions of the intestine, and (2) a discrete number of E.faecalis antigens induce dysregulated T cell immune responses, leading to the induction and perpetuation of chronic intestinal inflammation. These hypotheses are addressed in the following Specific aims: 1. Identify the mechanisms by which E.faecalis and E. coli, alone and in combination, induce different disease phenotypes in the same genetically susceptible host, the IL-10-/- mouse, by: a. Comparing virulence factors (epithelial adherence and invasion) of E. coli and E.faecalis shown to differentially induce distinct disease phenotypes in monoassociated IL-10-/- mice to known adherent/ invasive E. coli (AIEC) strains isolated from human Crohn's disease patients, and randomly isolated commensal E.coli and E.faecalis strains from SPF IL-10-/- mice with colitis and WT mice. b. Determining in vivo regional differences in mucosal adherence and invasion by each bacterial species in IL-10-/- mice co-colonized with these two bacterial species. c. Investigating the ability of adoptively transferred CD4+ cells isolated from colitic IL-10-/'- mice monoassociated with E. coli or E.faecalis to induce regionally specific intestinal inflammation and variable disease kinetics in immunodeficient mice colonized with either or both bacterial species. 2. Identify dominant E.faecalis antigens activating T cells in monoassociated IL-10-/- mice by: a. Determining the dominant antigens (identified in an expression library screened by serologic responses) that induce interferon-gamma (IFN-gamma) responses in CD4+ T cells from the mesenteric lymph nodes of E.faecalis - monoassociated IL-10-/- mice with colitis. b. Identifying the specific epitope(s) involved in immune activation and subsequent perpetuation of intestinal inflammation in IL-10-/- mice through truncation mutagenesis. c. Determining if recombinant nonpathogenic bacteria engineered to expressing the dominant E.faecalis epitope can induce T cell - mediated colitis and duodenitis.