Tuning peptide specifities for T cell tolerance in Type 1 diabetes

项目概要/摘要 1型糖尿病（T1 D）是一种典型的T细胞介导的自身免疫性疾病，大量数据表明 胰岛素作为T1 D疾病中的显性自身抗原。在T1 D的NOD小鼠模型中，值得注意的研究表明， 缺乏天然胰岛素表达的小鼠，但具有改变的胰岛素序列以维持血糖水平， 完全不受胰岛炎和糖尿病的影响越来越多的证据也表明胰岛素肽结合 在MHC II类（肽寄存器）内的方向和取向在确定相互作用的强度方面是重要的， 通过自身反应性T细胞识别。与Kappler实验室合作，我们发现了一种不寻常的肽 优势胰岛素表位InsB的结合特征：9-23。大多数InsB：9-23特异性CD 4 + T细胞 在外周识别胰岛素结合在这个不寻常的寄存器3，并通过敲入一个氨基酸， 在NOD小鼠（Ins 2 EE/+）中，仅将胰岛素基因的一个拷贝变异（R至E）转化为胰岛素基因的一个拷贝，小鼠完全受到保护 对抗糖尿病 胰岛素优势表位的“超级激动剂”版本的开发使我们能够解决几个问题， 围绕肽生成的生化途径，MHC分子的呈递， 和自身反应性致病性T细胞的免疫抑制。胰岛素基因中主要表位的突变 CD 4 + T效应细胞或Treg细胞特异性这些替代表位发展？是这些的模拟表位 能够显著改变疾病结果的致病性表位？我们是否能够微调这些表位 改变耐受机制，从缺失转变为Treg诱导？我们实验室最近的工作集中在 在关键小鼠背景上识别胰岛素特异性库，我们计划利用这些工具 和良好表征的小鼠模型，以检查改变胰岛素表达的影响，胸腺和 胸腺外的这些工具以及我们在产生大量TCR转基因小鼠方面的经验， 线将使我们能够在T1 D的背景下解决这些问题。 因此，我们假设，表位呈递和TCR亲和力的改变驱动了TCR的调节。 TCR库朝向耐受性和远离自身反应性。使用胰岛素作为模型抗原，我们 建议通过以下具体目标来检验我们的假设： 目的1：明确胰岛素反应性克隆缺失后中枢耐受的作用 目的2：描述外周耐受对胰岛素反应性T细胞的影响 目的3：探索显性耐受的机制，以了解将其转化为 T1 D的治疗 通过这些实验，我们希望能够对胰岛素表位的变化以及 抗原性驱动糖尿病的发病机制，并确定未来免疫调节的靶点， T1 D治疗和预防的治疗干预。

Project Summary/Abstract Type 1 Diabetes (T1D) is a classical T-cell mediated autoimmune disease and substantial data implicates insulin as a dominant autoantigen in T1D disease. In the NOD mouse model of T1D, notable studies have shown that mice lacking native insulin expression, but with an altered insulin sequence to maintain blood glucose levels, are completely protected from insulitis and diabetes. Growing evidence also indicates that insulin peptide binding and orientation within MHC Class II (peptide register) is important in determining the strength of interaction and recognition by autoreactive T cells. In collaboration with the Kappler lab, we have uncovered an unusual peptide binding characteristic of the dominant insulin epitope InsB:9-23. The majority of InsB:9-23-specific CD4+ T cells in the periphery recognize insulin bound in this unusual register 3, and by knocking in a single amino acid variation (R to E) into just one copy of the insulin gene in NOD mice (Ins2EE/+), the mice are completely protected against diabetes. The development of a “super agonist” version of the insulin dominant epitopes allows us to address several key questions surrounding the biochemical pathways of peptide generation, presentation by MHC molecules, and recognitions by auto-reactive pathogenic T cells. Do mutations of the major epitope in the insulin gene allow CD4+ T effectors or Treg cells specific for these alternative epitopes to develop? Are mimotopes of these pathogenic epitopes capable of dramatically altering disease outcomes? Are we able to fine tune these epitopes to alter tolerance mechanisms to shift from deletion to Treg induction? Recent work in our lab has focused on the identification of the insulin-specific repertoire on key mouse backgrounds, and we plan to utilize these tools and well-characterized mouse models to examine the effects of altering insulin expression, thymically and extrathymically. These tools as well as our experience with the generation of numerous TCR-transgenic mouse lines will allow us to address these questions in the context of T1D. Thus, we hypothesize that alterations to epitope presentation and TCR affinity drive the tunning of the TCR repertoire towards tolerance and away from self-reactivity. Using Insulin as a model antigen, we propose to test our hypothesis through the following specific aims: Aim 1: Define the role of central tolerance upon the deletion of insulin-reactive clones Aim 2: Characterize the effects of peripheral tolerance on insulin-reactive T cells Aim 3: Explore mechanisms of dominate tolerance to understand the potential for translation into therapeutic treatments for T1D Through these experiments, we hope to gain a nuanced understanding of how changes in insulin epitopes and antigenicity drive the pathogenesis of diabetes and identify targets for future immune modulation and therapeutic intervention for T1D treatment and prevention.