The Role of Microbial Antigen-Specific T Cells in Crohn's disease

微生物抗原反应性T细胞是炎症性损伤动物模型中的主要效应者， 克罗恩病，仅在肠道微生物群存在时引起T细胞介导的结肠炎。通过专注于 提出了T细胞在克罗恩病炎症中类似的关键作用，我们假设， 是克罗恩病患者高度共有的，并且表征异常的B细胞应答，是克罗恩病的潜在标志物。 存在对相同的肠道抗原（但不同的表位）反应的T细胞克隆型。 值得注意的是，抗CBir 1鞭毛蛋白抗体的存在是严重的、复杂的 克罗恩病。 我们的初步数据表明，这一长期项目的成功至关重要的两个特点。第一、 有一种疾病特异性的扩增T细胞库（由TCRβ CDR 3序列定义）， 在克罗恩病患者中高度共享，使得这些T细胞的抗原反应性的研究与克罗恩病的治疗相关。 大多数患者。其次，这种高度共享的T细胞库与共享血清的模式有关， 抗鞭毛蛋白抗体本身仅限于克罗恩病患者，这表明可能存在联系， 异常的B细胞和T细胞反应之间的联系。 为了完成这项研究，我们将招募活动期克罗恩病患者以及缓解期克罗恩病患者， 活动性溃疡性结肠炎患者和健康对照，以检测 血清抗体对一组肠道微生物抗原和TCRβ CDR 3库的反应性。目标是 鉴定与同源鞭毛蛋白抗原偶联高价值CDR 3序列。我们计划定义 这些TCRβ CDR 3序列在外周血和肠组织T细胞亚群中的分布（效应子， 调节和记忆），目的是鉴定分离到特定区室的序列，或 表型，并观察记忆T细胞亚群是否是高度共享的TCRβ CDR 3克隆型的储库。 最后，我们将测量哪些TCRβ CDR 3克隆型在特异性抗原后在体外扩增 暴露以鉴定候选抗原特异性序列并测试其与抗原的显著关联 血清阳性和细胞表型。然后，这些数据将用于从不同的组织中分离单个T细胞。 共享相同的扩增TCRβ CDR 3克隆型的个体，以比较 结构（α/β配对）、MHC特异性和抗原识别。重点将是针对高度 共享的TCRβ CDR 3序列与抗原特异性反应（细胞因子）紧密相关， 产生、增殖）和多个克罗恩病患者的血清阳性。 该项目的长期目标是以这些数据为基础，旨在确定机制的层次结构 （抗原肽结合基序，MHC混杂，例如）这有助于共享抗原反应性， 克罗恩病患者，开发破坏抗原特异性T细胞活化的策略，并评估 靶向微生物抗原反应性T细胞作为克罗恩病治疗方法的可行性和价值。

Microbial-antigen reactive T cells are the primary effectors of inflammatory damage in animal models of Crohn's disease, causing T cell-mediated colitis only in the presence of gut microbiota. By focusing on a proposed similar key role for T cells in Crohn's inflammation, we hypothesize that anti-flagellin antibodies that are highly shared by Crohn's patients, and characterize an aberrant B cell response, are potential markers for the presence T cell clonotypes that are reactive to the same gut commensal antigens (but different epitopes). Of note, the presence of anti-CBir1 flagellin antibodies is the strongest predictor of severe, complicated Crohn's disease. Our preliminary data demonstrate two features critical to the success of this long-term project. First, there is a disease-specific repertoire of expanded T cells (defined by TCRβ CDR3 sequences) that is very highly shared among Crohn's patients, making the study of these T cells' antigen reactivity relevant for the majority of patients. Second, this highly shared T cell repertoire is associated with patterns of shared serum anti-flagellin antibodies that are themselves restricted to Crohn's disease patients, suggesting a potential link between aberrant B cell and T cell responses. To accomplish this study, we will enroll active Crohn's patients as well as remission Crohn's patients, active ulcerative colitis patients and healthy controls to test for significant associations between profiles of serum antibody reactivity to a panel of gut microbial antigens and the TCRβ CDR3 repertoire. The goal is to identify high value CDR3 sequences that couple with cognate flagellin antigens. We plan to define the distribution of these TCRβ CDR3 sequences among peripheral blood and gut tissue T cells subsets (effector, regulatory and memory) with the goal of identifying sequences that segregate to a particular compartment or phenotype and to see if the memory T cell subset is a reservoir of highly shared TCRβ CDR3 clonotypes. Lastly we will measure which TCRβ CDR3 clonotypes are expanded in vitro following specific antigen exposure to identify candidate antigen-specific sequences and test for their significant association with antigen seropositivity and cell phenotype. These data will then be used to isolate single T cells from different individuals who share identical expanded TCRβ CDR3 clonotypes in order to compare the similarity of structure (α/β pairing), MHC specificity, and recognition of antigen. The focus will be on targeting highly shared TCRβ CDR3 sequences that have been robustly linked with antigen-specific responses (cytokine production, proliferation) and seropositivity across multiple Crohn's patients. The long-term goals of this project build on these data and aim to define the hierarchy of mechanisms (antigen peptide binding motifs, MHC promiscuity, e.g.) that contribute to shared antigen reactivity among Crohn's patients, to develop strategies that disrupt the antigen-specific T cell activation, and to assess the feasibility and value of targeting microbial antigen-reactive T cells as a treatment approach in Crohn's disease.