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

项目摘要 鉴定参与1型糖尿病（T1 D）发病机制的抗原对于开发 T1 D的生物标志物和疗法。最近的努力集中在识别识别的抗原 T1 D器官供体的残余胰岛内的T细胞，因为这样的T细胞可能是 参与疾病的发病机制。我们研究胰岛浸润性CD 8 T细胞的初步数据表明， 很大一部分，1/3到1/2的T1 D器官供体，对前胰岛素原（PPI）肽有反应性，而 剩余的供体在胰岛中只有很少或没有PPI反应性CD 8 T细胞。PPI识别的表位- 反应性CD 8 T细胞由跨越HLA-A、B和C的许多HLA I类分子呈递，并被扩散 在PPI蛋白中有几个热点，优先被多种T细胞受体识别 (TCR)由T细胞表达。因此，前胰岛素原是一种主要的自身抗原，含有T1 D-的表位 相关的CD 8 T细胞在T1 D患者的子集。然而，胰岛浸润性T细胞靶向的抗原， 其余患者存在于PPI之外，表明胰岛居民靶向抗原特异性的异质性 CD 8 T细胞。为了实现开发T1 D的抗原特异性生物标志物和疗法的最终目标， 重要的问题仍然存在：（1）哪些抗原被不反应的胰岛浸润性CD 8 T细胞识别 在PPI？(2)通过测量外周血的反应性，我们能识别出具有特定抗原的患者吗？ 为了给每个病人设计合适的治疗方案，这项提案的目的是揭露 胰岛来源的CD 8 T细胞识别的未知抗原特异性，并评估 外周血中的PPI反应性和对口服胰岛素的反应作为个性化抗原的原理证明- 具体治疗。我们的中心假设是胰岛来源的CD 8 T细胞自身抗原特异性的异质性， 细胞存在并决定对抗原特异性免疫疗法的应答。如果这个假设是正确的，那么， CD 8 T细胞靶向的抗原可用于鉴定具有特定抗原特异性的患者， 接受抗原特异性免疫疗法以预防T1 D的应答者。为了验证这个假设，我们 将以蛋白质靶向的方式鉴定由胰岛浸润性CD 8 T细胞识别的抗原（Aim 1)2.以无偏见的方式（Aim 2）。鉴于我们的初步结果，PPI是胰岛浸润的主要抗原， CD 8 T细胞亚群的患者中，我们将重点关注PPI，以测试CD 8 T细胞与PPI之间是否存在关联。 PPI反应性和对口服胰岛素治疗的反应（目的3）。该提案的成功完成将 导致T1 D患者中胰岛驻留CD 8 T细胞的主要自身抗原的鉴定。的识别 抗原可用于基于CD 8 T细胞抗原特异性对异质性T1 D患者进行分类， 目标是最终为T1 D预防工作提供适当的个性化抗原特异性免疫疗法。

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.