Antigens Recognized by CD8+ T Cells in Type 1 Diabetes

描述（由申请人提供）：1型糖尿病（T1D）是一种以T细胞介导的胰岛细胞破坏为特征的自身免疫性疾病。在该疾病的NOD小鼠模型中，CD8+ T细胞是必需的致病效应物，已经开始显示出作为治疗靶点的希望。针对β细胞抗原的CD8+ T细胞也存在于T1D患者的外周血。我们正致力于利用树突状细胞（DC）的强效耐受性特性，开发针对CD8+ T细胞的T1D免疫治疗干预。我们发现，抗原通过DC内吞受体DEC-205靶向稳态DC，即使在已知耐受缺陷的NOD小鼠持续自身免疫的情况下，也能导致T细胞耐受。将这一战略过渡到人类疾病将需要更好地了解其治疗效果和决定其结果的因素。还需要开发和评估适合人类使用的抗原递送试剂以及适合其测试的临床前模型，还需要确定与大量患者相关的抗原靶点。这些需要将在完成续期申请中提出的具体目标后全部得到满足。在Aim 1中，使用小鼠和人类T细胞，我们将测试T细胞受体（TCR）亲和力和/或先前抗原经历影响通过抗dec -205传递到稳态DC的抗原暴露的结果的假设，结果可能包括T细胞缺失、无反应性或调节表型的发展。这些研究将使用具有确定和可变亲和力的tcr集进行。在Aim 2中，我们将验证通过anti-DEC-205将多个关键CD8+ T细胞表位同时递送到DC将导致NOD小鼠和NOD.m¿2m-/-. hhd （HLA-A2）的病程改善的假设。hDEC-205小鼠将在这里开发。在Aim 3中，我们将使用NOD小鼠的胰岛浸润细胞转基因四种HLA分子中的一种来检测受HLA限制的CD8+ T细胞对重要的β细胞抗原IGRP和胰岛素的反应，我们将在这里进一步设计这些HLA分子来表达人类IGRP或胰岛素。由于要检测的每个HLA分子都代表一个独特的HLA超型，并且使用一个超型成员识别的肽通常也会结合该超型的其他成员，我们使用表达人类β细胞抗原的HLA转基因小鼠小组识别表位的策略应该会导致与大量患者和高危个体相关的监测和治疗试剂。我们提出的研究将对T1D抗原特异性治疗的发展具有重要意义，并将提供有助于指导该疾病免疫调节治疗的未来发展的信息。

DESCRIPTION (provided by applicant): Type 1 diabetes (T1D) is an autoimmune disease characterized by T cell-mediated destruction of the pancreatic islet beta cells. In the NOD mouse model of the disease, CD8+ T cells are required pathogenic effectors that have begun to show promise as therapeutic targets. CD8+ T cells specific for beta cell antigens are also present in the peripheral blood of T1D patients. We are working to harness the potent tolerogenic properties of dendritic cells (DC) to develop an immunotherapeutic intervention for T1D that targets CD8+ T cells. We have found that antigen targeting to steady-state DC via the DC endocytic receptor DEC-205 can lead to T cell tolerance even in the context of ongoing autoimmunity in NOD mice with known tolerance defects. Transition of this strategy to the human disease will require a better understanding of its therapeutic efficacy and the factors that determine its outcome. Antigen delivery reagents appropriate for human use, and preclinical models suitable for their testing, will also need to be developed and evaluated, and the identification of antigenic targets relevant to large numbers of patients will also be required. These needs will all be met upon completion of the Specific Aims proposed in this renewal application. In Aim 1, using both murine and human T cells, we will test the hypothesis that T cell receptor (TCR) affinity and/or prior antigen experience influence the outcome of exposure to an antigen delivered to steady-state DC via anti-DEC-205, an outcome that can range from T cell deletion, non-responsiveness, or development of a regulatory phenotype. These studies will be conducted using sets of TCRs having defined and variable affinities. In Aim 2, we will test the hypothesis that simultaneous delivery of multiple critical CD8+ T cell epitopes to DC via anti-DEC-205 will lead to improvement of disease course in NOD mice and in NOD.m¿2m-/-.HHD(HLA-A2).hDEC-205 mice to be developed here. In Aim 3, we will examine the HLA-restricted CD8+ T cell response to the important beta cell antigens IGRP and insulin using islet-infiltrating cells from NOD mice transgenic for one of four HLA molecules that we will additionally engineer here to express human IGRP or insulin. As each HLA molecule to be examined is representative of a unique HLA supertype, and a peptide identified using one supertype member will often also bind other members of that supertype, our strategy to identify epitopes using our panel of HLA- transgenic mice expressing human beta cell antigens should result in monitoring and therapeutic reagents relevant to large numbers of patients and at-risk individuals. Our proposed studies will have important implications for the development of antigen-specific therapeutics for T1D and will provide information that will help to guide the future development of immunomodulatory therapies for this disease.