Antigens Recognized by CD8+ T Cells in Type 1 Diabetes

描述（由申请人提供）：1型糖尿病（T1 D）是一种自身免疫性疾病，其特征在于T细胞介导的胰岛β细胞破坏。在NOD小鼠模型中，CD 8 + T细胞是所需的致病效应子，已开始显示出作为治疗靶点的希望。对β细胞抗原特异性的CD 8 + T细胞也存在于T1 D患者的外周血中。我们正在努力利用树突状细胞（DC）的有效致耐受特性，以开发针对CD 8 + T细胞的T1 D免疫干预。我们已经发现，通过DC内吞受体DEC-205靶向稳态DC的抗原可以导致T细胞耐受，即使在具有已知耐受缺陷的NOD小鼠中正在进行的自身免疫的背景下也是如此。将这一策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，还需要鉴定与大量患者相关的抗原靶点。这些需求将在完成本续期申请中提出的具体目标后得到满足。在目的1中，使用鼠和人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暴露于通过抗DEC-205递送至稳态DC的抗原的结果的假设，该结果可以从T细胞缺失、无应答性或调节表型的发展变化。这些研究将使用具有确定和可变亲和力的TCR组进行。在目的2中，我们将测试以下假设：通过抗DEC-205同时递送多个关键的CD 8 + T细胞表位至DC将导致在NOD小鼠和在这里开发的NOD.m <$2m-/-.HHD（HLA-A2）.hDEC-205小鼠中的疾病进程的改善。在目标3中，我们将使用来自NOD小鼠的胰岛浸润细胞检测HLA限制性CD 8 + T细胞对重要β细胞抗原HRP和胰岛素的应答，所述NOD小鼠转基因为四种HLA分子之一，我们将在此另外工程化以表达人HRP或胰岛素。由于待检查的每个HLA分子代表独特的HLA超型，并且使用一个超型成员鉴定的肽通常也将结合该超型的其他成员，因此我们使用表达人β细胞抗原的HLA转基因小鼠组鉴定表位的策略应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T1 D抗原特异性治疗的发展产生重要影响，并将提供有助于指导这种疾病免疫调节治疗未来发展的信息。 公共卫生相关性：我们的工作将为1型糖尿病的抗原特异性疗法的发展奠定基础，1型糖尿病是一个日益严重的健康问题，与显著的发病率和死亡率相关。拟议的工作旨在诱导免疫耐受性，以响应稳态树突状细胞对β细胞抗原的呈递，并确定将提供广泛人群覆盖的治疗和免疫监测目标。

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. PUBLIC HEALTH RELEVANCE: Our work will lay a foundation for the development of antigen-specific therapies for type 1 diabetes, which is a growing health problem that is associated with significant morbidity and mortality. The proposed work seeks to induce immunological tolerance in response to presentation of beta cell antigens by steady-state dendritic cells and to identify therapeutic and immune monitoring targets that will provide broad population coverage.