Self-Reactive T Cell Development in Type 1 Diabetes

项目摘要（Abstract）： I型糖尿病（T1 D）是一种早期发病的自身免疫性疾病，最终导致胰岛素的靶向破坏 产生胰岛内的胰岛细胞。前两大遗传易感性 与1型糖尿病发展相关的决定因素与抗原呈递和抗原 可用性（HLA和INS-VNTR）。这些和其他易感等位基因的鉴定突出了一种潜在的 对胰岛抗原的中枢和外周耐受性缺陷。因此，研究集中在基本的 自身免疫性T细胞选择的各个方面对于确定导致免疫缺陷的关键机制至关重要。 中央宽容目前还不清楚T细胞之间的细胞内信号传导和转录谱是如何不同的 选择天然表达的高亲和力肽（潜在的自身免疫抗原）与低亲和力肽 肽（正常的积极选择）在胸腺发育。失去自我耐受性的机制 似乎是多方面的，而且人们对它的了解很少。现在很明显，除了易感性等位基因， 自身免疫性糖尿病也与作为新抗原的免疫后修饰的表位有关 并帮助丧失自我耐受性。特异性针对新抗原的病原性T细胞在肿瘤细胞中唯一表达， 胰腺可能通过一种被称为无知的过程逃脱胸腺的选择。非肥胖糖尿病小鼠 模型提供了一个体内系统来剖析胸腺中自身反应性T细胞发育的机制， 在人类身上是不可行的。与建立在模型抗原上的系统不同，NOD小鼠提供了一种遗传学上的 易感背景，其中关键靶抗原经历翻译后修饰，导致 自发性糖尿病发展。因此，研究自身免疫性TCR的筛选具有重要意义 在NOD小鼠中自发地逃脱了负选择。这种方法的局限性在于 可用的自身抗原特异性TCR转基因NOD小鼠的数量。此应用程序充分利用了我们的优势 我们在产生胰岛素特异性TCR逆转录小鼠方面的经验以及我们对 胸腺细胞发育和TCR信号传导。因此，本申请的范围将限于并集中于 解剖特定的信号机制，使胸腺选择自身免疫胰岛素， 嗜铬粒蛋白反应性II类限制性TCR。在目标1中，我们将使用InsB：9-23 TCR 接触突变体，p16 A，以确定高和低的阳性和阴性选择的细胞机制， 胰岛素反应性胸腺细胞。在目标2中，我们将确定新生儿早期胸腺抗原暴露的影响 小鼠对胰岛抗原的终身耐受性。从这些研究中收集的信息可能具有重要意义。 对我们理解自身反应性T细胞如何逃避缺失以及抗原特异性Treg 发展发生，导致新的方法来建立对胰岛抗原的耐受性。

Project Summary (Abstract): Type I Diabetes (T1D) is an early onset autoimmune disease that culminates in the targeted destruction of insulin producing  cells found within the pancreatic islets of Langerhans. The top two genetic susceptibility determinants associated with development of Type 1 Diabetes are related to antigen presentation and antigen availability (HLA and INS-VNTR). The identification of these and other susceptibility alleles highlight a potential deficiency in central and peripheral tolerance to islets antigens. Therefore, studies focused on the fundamental aspects of autoimmune T cell selection are crucial in identifying the key mechanisms that lead to the loss of central tolerance. It is still unclear how the intracellular signaling and transcriptional profiles differ between T cells selected on naturally expressed high affinity peptides (potential autoimmune antigens) versus low affinity peptides (normal positive selection) during thymic development. The mechanisms behind loss of self-tolerance appear to multifaceted and poorly understood. It is now evident that in addition to susceptibility alleles, autoimmune diabetes is also associated with post-translationally modified epitopes that serve as neo-antigens and aide in loss of self-tolerance. Pathogenic T cells that are specific for neo-antigens uniquely expressed in the pancreas may escape thymic selection by a process known as ignorance. The Non-Obese Diabetic mouse model offers an in vivo system to dissect the mechanisms of autoreactive T cell development in the thymus that is not feasible in humans. Unlike systems build on model antigens, the NOD mouse offers a genetically susceptible background where key target antigens undergo post-translational modification leading to spontaneous diabetes development. Therefore, it is of high importance to study selection of autoimmune TCRs that have spontaneously escaped negative selection in NOD mice. A limitation to such approach is the limited number of available autoantigen-specific TCR transgenic NOD mice. This application capitalizes on our strengths and experience in generating insulin specific TCR retrogenic mice as well as our in-depth knowledge of thymocyte development and TCR signaling. The scope of this application will therefore be limited to, and focused on, dissecting specific signaling mechanisms that allow thymic selection of autoimmune insulin and chromogranin reactive Class-II restricted TCRs. In Aim 1 of the proposed work, we will use the InsB:9-23 TCR contact mutant, p16A, to determine the cellular mechanisms for positive and negative selection of high and low insulin reactive thymocytes. In Aim 2, we will determine the impact of early thymic antigen exposure in neonatal mice on life-long tolerance to islet antigens. Information gathered from these studies may have a significant impact on our understanding of how autoreactive T cells escape deletion and how antigen specific Treg development occurs, leading to novel approaches to establish tolerance to islet antigens.