Autoantigens targeted by CD8 T cells in type 1 diabetes: from islets to blood

项目摘要 识别参与1型糖尿病(T1D)发病机制的抗原对疾病的发展至关重要 T1D的生物标志物和治疗。最近的努力集中在识别已识别的抗原上。 T1D器官捐赠者残余胰岛内的T细胞，因为前提是这些T细胞很可能是 参与疾病的发病机制。我们对胰岛浸润性CD8 T细胞的初步研究数据表明 很大比例的T1D器官捐赠者，1/3到1/2对胰岛素原(PPI)多肽有反应，而 其余的供者在胰岛中只有很少的或没有PPI反应的CD8 T细胞。PPI识别的表位- 反应性CD8T细胞由许多跨越HLAA、B和C的HLAI类分子呈递，并广泛分布 在整个PPI蛋白中，有几个被多个T细胞受体优先识别的热点 (TCR)由T细胞表达。因此，前胰岛素原是一种主要的自身抗原，包含T1D- T1D患者亚群中的相关CD8 T细胞。然而，由胰岛浸润性T细胞靶向的抗原 其余患者存在于PPI之外，这表明胰岛居民靶向的抗原特异性不同 CD8T细胞。朝着开发T1D抗原特异性生物标记物和疗法的最终目标，两个 重要的问题仍然存在；(1)没有反应的胰岛浸润性CD8 T细胞识别哪些抗原 用PPI？(2)通过测量外周血中的反应性，我们能识别出具有特定抗原的患者吗？ 为了为每个患者设计合适的治疗方法，是否具有特异性？这项提议的目标是揭开 胰岛来源的CD8 T细胞识别未知的抗原特异性并评估两者之间的关联 外周血中PPI的反应性和对口服胰岛素的反应作为个性化抗原原理的证据 特定的疗法。我们的中心假设是胰岛来源的CD8T自身抗原特异性的异质性 细胞的存在决定了对抗原特异性免疫治疗的反应。如果这一假设是正确的，那么自我 以CD8 T细胞为靶点的抗原可用于识别具有特定抗原特异性的患者以选择 接受抗原特异性免疫疗法以预防T1D的应答者。为了检验这一假设，我们 将以蛋白质靶向方式(AIM)识别由胰岛浸润性CD8 T细胞识别的抗原 1)以不偏不倚的方式(目标2)。鉴于我们的初步结果，PPI是胰岛浸润性的主要抗原 在CD8T细胞亚群中，我们将重点研究PPI来检验CD8T细胞与PPI是否存在关联 PPI反应性和口服胰岛素治疗的反应(目标3)。这项提议的成功完成将 结果鉴定了T1D患者胰岛驻留CD8T细胞的主要自身抗原。身份的鉴定 抗原可用于根据CD8T细胞抗原特异性对异质性T1D患者进行分类 目的最终为T1D的预防工作提供适当的个性化抗原特异性免疫治疗。

Project Summary Identification of antigens that are involved in the pathogenesis of type 1 diabetes (T1D) is crucial to develop biomarkers and therapies for T1D. There have been recent efforts focused on identifying antigens recognized by T cells within the residual islets of T1D organ donors due to the premise that such T cells are likely to be involved in disease pathogenesis. Our preliminary data studying islet-infiltrating CD8 T cells demonstrates that a large proportion, 1/3 to 1/2 of T1D organ donors, are reactive to preproinsulin (PPI) peptides, whereas the remaining donors have only few or no PPI-reactive CD8 T cells in the islets. Epitopes recognized by the PPI- reactive CD8 T cells are presented by many HLA class I molecules spanning HLA-A, B, and C, and are spread throughout the PPI protein with several hot spots that are preferentially recognized by multiple T cell receptors (TCR) expressed by the T cells. Thus, preproinsulin is a major self-antigen and contains epitopes for T1D- associated CD8 T cells in a subset of T1D patients. Yet antigens targeted by islet-infiltrating T cells in the remaining patients exist outside PPI, suggesting heterogeneity in antigen specificity targeted by islet-resident CD8 T cells. Towards an ultimate goal of developing antigen-specific biomarkers and therapies for T1D, two important questions remain; (1) What antigens are recognized by islet-infiltrating CD8 T cells that do not react with PPI? (2) By measuring reactivity in peripheral blood, can we identify patients that have a particular antigen specificity in order to design appropriate therapy for each patient? The goal of this proposal is to uncover unknown antigen specificities recognized by islet-derived CD8 T cells and to evaluate the association between PPI reactivity in peripheral blood and the response to oral insulin as a proof of principle for personalized antigen- specific therapies. Our central hypothesis is that heterogeneity in self-antigen specificity for islet-derived CD8 T cells exists and determines the response to antigen-specific immunotherapy. If this hypothesis is correct, self- antigens targeted by CD8 T cells can be utilized to identify patients with particular antigen specificity to select for responders receiving antigen-specific immunotherapies for T1D prevention efforts. To test the hypothesis, we will identify antigens that are recognized by islet-infiltrating CD8 T cells either in a protein-targeted manner (Aim 1) and in an unbiased manner (Aim 2). Given our preliminary results that PPI is a major antigen for islet-infiltrating CD8 T cells in a subset of patients, we will focus on PPI to test whether there is an association between CD8 PPI reactivity and the response to oral insulin treatment (Aim 3). The successful completion of this proposal will result in identification of major self-antigens for islet-resident CD8 T cells in T1D patients. The identification of antigens can be used to classify heterogeneous T1D patients based on CD8 T cell antigen specificity with the goal to ultimately providing appropriate personalized antigen-specific immunotherapy for T1D prevention efforts.