The Antigen Repertoire of CD4 T cells from Pancreatic Islets

项目摘要 1型糖尿病(T1D)是一种组织特异性自身免疫性疾病。与人类白细胞抗原分类有很强的遗传关联 II基因位点提示CD4T细胞在疾病的启动和驱动过程中具有重要作用。我们和其他人 已经从T1D器官捐赠者的胰腺中分离出T细胞，并确定了胰岛素的T细胞表位， 及其前体胰岛素原，以及融合肽。一个重要的下一步是阐明表型。 这种胰岛来源的T细胞在健康和疾病中的作用。同时，之前的研究揭示了这样一个事实 胰岛中大多数T细胞的抗原仍不清楚，我们甚至不知道这些T细胞是否 是胰岛抗原特异性的。识别胰岛-CD4T细胞的抗原特异性是解剖疾病的关键 致病性和异质性开发抗原特异性免疫疗法以阻止疾病进展 特定个体中的适当抗原。因此，这项资助的目的是鉴定cd4的抗原特异性。 胰岛中的T细胞，并将抗原特异性反应与T细胞表型联系起来。 多条证据表明，在亚群中可能存在共同的或首选的CD4T细胞表位 在T1D患者中。首先，绝大多数T1D患者具有危险的人类白细胞抗原II类等位基因，以及特定的II类等位基因 与初始胰岛自身抗体的形成有关(例如，胰岛素自身抗体在患有 人类白细胞抗原-DR4、谷氨酸脱羧酶-65抗体和人类白细胞抗原-DR3)。第二，CD4T细胞具有相同的 在胰腺中检测到抗原特异性(例如胰岛素原多肽和混合胰岛素多肽)。 多个T1D器官捐赠者，在T1D早期患者的血液中发现了同样的反应。 最后，针对这些表位的CD4T细胞在T1D患者的血液中具有炎症表型 与非糖尿病对照组相比。这导致我们假设胰岛自身免疫被促进并 由具有特定人类白细胞抗原的T1D患者共有的共同抗原反应的CD4T细胞调节 第二类分子。我们将确定胰岛中组织特异性CD4T细胞的比例(目标1)并寻求 确定T1D器官捐献者胰岛中CD4T细胞靶向的表位(目标2)。此外，我们还将 小鼠胰腺和脾组织胰岛抗原特异性T细胞分子表型的测定 患有和不患有T1D的器官捐赠者(目标3)。这项提议的成功完成将：(1)识别抗原 在T1D发育阶段和(2)胰岛中的CD4T细胞靶向的表位 阐明导致这些T细胞致病的分子表型和特征。因此，这些研究将 增强我们对人类T1D发病机制的理解，剖析疾病的异质性，并帮助改进 评估抗原特异性免疫疗法预防糖尿病的临床试验设计。

Project Summary Type 1 diabetes (T1D) is a tissue-specific autoimmune disorder. Strong genetic association with the HLA class II gene locus suggests the importance of CD4 T cells in initiating and driving the disease process. We and others have isolated T cells from the pancreas of T1D organ donors and identified T cell epitopes specific to insulin, and its precursor preproinsulin, as well as fusion peptides. An important next step is to elucidate the phenotypes of such islet-derived T cells in health and disease. Concurrently, the previous studies uncovered the fact that antigens for the majority of T cells in the islets are still unknown, and we do not even know whether those T cells are islet antigen-specific. Identifying antigen specificity of islet-CD4 T cells is critical to dissect disease pathogenicity and heterogeneity to develop antigen-specific immunotherapy to halt disease progression using appropriate antigens in a given individual. Therefore, the goal of this grant is to identify antigen specificity of CD4 T cells in the islets and link antigen-specific responses to T cell phenotypes. Multiple lines of evidence suggest that there may be `common' or preferred CD4 T cell epitopes within subsets of T1D patients. First, the vast majority of T1D patients have risk HLA class II alleles, and specific class II alleles are associated with development of an initial islet autoantibody (e.g. insulin autoantibodies develop in those with HLA-DR4, and glutamic acid decarboxylase-65 antibodies with HLA-DR3). Second, CD4 T cells having the same antigen specificity (e.g. proinsulin peptides and hybrid insulin peptides) are detected in the pancreata from multiple T1D organ donors, and the same reactivity is found in the blood of those with early stages of T1D. Finally, CD4 T cells specific to these epitopes have an inflammatory phenotype in the blood of T1D patients compared to non-diabetic controls. This leads us to hypothesize that islet autoimmunity is promoted and regulated by CD4 T cells reacting to `common' antigens that are shared by T1D patients having specific HLA class II molecules. We will determine the proportion of tissue-specific CD4 T cells in the islets (Aim 1) and seek to identify epitopes targeted by CD4 T cells in the islets of T1D organ donors (Aim 2). Furthermore, we will determine the molecular phenotype of islet antigen-specific T cells in the pancreatic lymph nodes and spleen of organ donors with and without T1D (Aim 3). The successful completion of this proposal will: (1) identify antigens and epitopes targeted by CD4 T cells from pancreatic islets across the stages of T1D development and (2) elucidate the molecular phenotype and features that render these T cells pathogenic. Thus, these studies will enhance our understanding of human T1D pathogenesis, dissect disease heterogeneity, and aid in improving the design of clinical trials evaluating antigen-specific immunotherapy for diabetes prevention.