INNATE AN ADAPTIVE IMMUNITY TO MICROBIAL FLAGELLINS IN IBD

IBD 中微生物鞭毛蛋白的先天适应性免疫

基本信息

批准号：
7486781
负责人：
CHARLES O ELSON
金额：
$ 24.97万
依托单位：
UNIVERSITY OF ALABAMA AT BIRMINGHAM
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-08-01 至 2010-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7486781
关键词：
Acute Address Adjuvant Antigen Presentation Antigens Autoimmune Diseases B-Lymphocytes Bacteria Bacterial Antigens Bacterial Proteins CD4 Positive T Lymphocytes Cells Chronic Colitis Congenic Mice Crohn&apos s disease Data Defect Dendritic Cells Disease Disease Progression Enteral Enterobacteriaceae Epitopes Experimental Models Flagellin Human Immune Immune response Immune system Immunity Immunization Immunodominant Antigens In Vitro Inbred C3H Mice Inflammatory disease of the intestine Interferon Type II Intestines Ligands Mesentery Mus Natural Immunity Numbers Patients Pattern Principal Investigator Proteins Reporter Resistance Severities Severity of illness Signal Transduction Susceptibility Gene T memory cell T-Cell Receptor T-Lymphocyte Testing Th1 Cells Time Toll-Like Receptor 5 Transgenic Mice Transgenic Organisms base commensal microbes immunoregulation in vivo interleukin-23 lymph nodes macrophage microbial microorganism antigen mouse model novel prevent programs response

项目摘要

Innate and Adaptive Immunity to Microbial Flagellins in IBD. Abnormalities of the host immune response to the intestinal microbiota is the basis of experimental IBD, and this is likely true in human IBD as well. We have cloned and sequenced a set of microbial proteins that serve as immunodominant antigens in experimental colitis. The largest group of these were previously unknown flagellins of the anaerobic commensal flora, which were recognized immunologically in multiple mouse models of IBD and in half of patients with Crohn's disease. Use of flagellins as probes has revealed an apparent deficiency in innate immunity in colitis-prone C3H/HeJBir mice (C3H), a response regulated by a C3H colitis-susceptibility gene locus on Chr 3 termed Cdcsl. Paradoxically this deficient innate response in C3H mice results in a increased T cell response to flagellins in vivo. Aim 1 will ask whether and how the dendritic cell and macrophage innate immune response to the microbiota is deficient in colitis-prone C3H compared to colitis-resistant C57BI/6 (B6) mice, and in C3H and B6 mice that are congenic for the Cdcs1 locus. Bacterial flagellins and other TLR ligands will be used as probes first, followed by challenge with gram-positive and gram-negative intestinal bacteria isolated from mice. The ability of C3H vs B6 dendritic cells to present microbial antigens to CD4 T cells will be assessed to test the hypothesis that the deficient acute C3H dendritic cell response to bacteria prolongs antigen presentation to T cells, thus resulting in a greater T cell responses in C3H mice. Further, we will ask whether flagellins can serve as adjuvants via Toll like receptor 5 (TLR5) for themselves or for other microbial antigens. Aim 2 will address for the first time whether there is a defined, repetitive, non-random pattern of spreading of the adaptive immune response to immunodominant enteric microbial antigens in IBD. Based on our preliminary data, the hypothesis to be tested is that a repetitive, hierarchical pattern of epitope spreading does occur in experimental IBD, similar to what has been observed in autoimmune diseases. We will determine if such epitope spreading is associated with disease progression, whether it requires TLR5, whether it is dependent on lnterleukin-23, and whether immunization with antigens recognized early in the spreading cascade can prevent reactivity to antigens recognized later and thus ameliorate intestinal inflammation. Aim 3 will define where, when, and how T cells become sensitized to microbial antigens in the colitis-prone host using two novel mouse lines, an interferon gamma-Thy1.1 reporter mouse and a TCR transgenic mouse reactive to CBiM bacterial flagellin. These studies will provide important new understanding of the mechanisms by which the host immune system responds to the microbiota and how an abnormal immune response to the microbiota results in chronic intestinal inflammation. Innate and adaptive response of Crohn's patients to these antigens will be assessed.

IBD 中微生物鞭毛蛋白的先天性和适应性免疫。宿主免疫异常对肠道微生物群的反应是实验性 IBD 的基础，在人类 IBD 中也可能如此。我们克隆并测序了一组作为实验性结肠炎免疫显性抗原的微生物蛋白。其中最大的一组是以前未知的厌氧共生菌群的鞭毛蛋白，这些鞭毛蛋白在多种 IBD 小鼠模型和一半的克罗恩病患者中被免疫学识别。使用鞭毛蛋白作为探针揭示了易患结肠炎的 C3H/HeJBir 小鼠 (C3H) 中先天免疫的明显缺陷，这是一种由 Chr 3 上称为 Cdcsl 的 C3H 结肠炎易感基因位点调节的反应。矛盾的是，C3H 小鼠的这种先天反应缺陷导致体内 T 细胞对鞭毛蛋白的反应增加。目标 1 将询问与耐结肠炎的 C57BI/6 (B6) 小鼠相比，易患结肠炎的 C3H 以及与 Cdcs1 同类的 C3H 和 B6 小鼠中，树突状细胞和巨噬细胞对微生物群的先天免疫反应是否以及如何缺乏轨迹。首先将细菌鞭毛蛋白和其他 TLR 配体用作探针，然后用从小鼠中分离的革兰氏阳性和革兰氏阴性肠道细菌进行攻击。将评估 C3H 与 B6 树突状细胞向 CD4 T 细胞呈递微生物抗原的能力，以检验以下假设：C3H 树突状细胞对细菌的急性反应不足会延长向 T 细胞呈递抗原，从而导致 C3H 中 T 细胞反应更强老鼠。此外，我们将询问鞭毛蛋白是否可以通过 Toll 样受体 5 (TLR5) 作为自身或其他微生物抗原的佐剂。目标 2 将首次解决 IBD 中针对免疫显性肠道微生物抗原的适应性免疫反应是否存在明确的、重复的、非随机的传播模式。根据我们的初步数据，要测试的假设是实验性 IBD 中确实发生了重复的、分层的表位扩散模式，类似于在自身免疫性疾病中观察到的情况。我们将确定这种表位扩散是否与疾病进展相关，是否需要 TLR5，是否依赖于白细胞介素 23，以及使用扩散级联早期识别的抗原进行免疫是否可以阻止对后来识别的抗原的反应，从而改善肠道炎症。目标 3 将定义 T 细胞在何处、何时以及如何变得敏感使用两种新型小鼠品系，即干扰素 γ-Thy1.1 报告小鼠和对 CBiM 细菌鞭毛蛋白有反应的 TCR 转基因小鼠，在易患结肠炎的宿主中检测微生物抗原。这些研究将为宿主免疫系统对微生物群作出反应的机制以及对微生物群的异常免疫反应如何导致慢性肠道炎症提供重要的新认识。将评估克罗恩病患者对这些抗原的先天和适应性反应。