Self-Reactive T Cell Development in Type 1 Diabetes

项目摘要(摘要)： I型糖尿病(T1D)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 在朗格汉斯人的胰岛中发现产生细胞。遗传易感性排名前两位 与1型糖尿病发生相关的决定因素与抗原提呈和抗原有关 可获得性(人类白细胞抗原和INS-VNTR)。对这些和其他易感等位基因的识别突出了一个潜在的 中枢和外周对胰岛抗原的耐受性不足。因此，研究重点放在了根本上 自身免疫T细胞选择的各个方面对于确定导致自身免疫功能丧失的关键机制至关重要。 中心容忍。目前还不清楚T细胞之间的细胞内信号和转录特征是如何不同的 选择自然表达的高亲和力多肽(潜在的自身免疫抗原)与低亲和力 胸腺发育过程中的多肽(正常阳性选择)。自我忍耐力丧失背后的机制 似乎是多方面的，也很难被理解。现在很明显，除了易感等位基因外， 自身免疫性糖尿病也与作为新抗原的翻译后修饰表位有关 以及帮助人们丧失自我宽容。对新抗原具有特异性的致病T细胞，在 胰腺可能通过一种被称为无知的过程来逃避胸腺的选择。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小鼠提供了一种基因上的 易感背景，主要靶抗原经过翻译后修饰导致 自发性糖尿病的发展。因此，对自身免疫性TCRs的筛选研究具有重要意义。 自然逃脱了NOD小鼠的负选择。这种方法的一个限制是有限的 可用的自身抗原特异性TCR转基因NOD小鼠的数量。这个应用程序充分利用了我们的优势 以及在制造胰岛素特异性TCR逆转录基因小鼠方面的经验以及我们对 胸腺细胞发育和TCR信号转导。因此，本申请的适用范围将限于并集中于 上，剖析了允许胸腺选择自身免疫性胰岛素和 嗜铬颗粒蛋白反应性II类限制性TCR。在拟议工作的目标1中，我们将使用InSb：9-23 TCR 接触突变体P16A确定正负向选择高低的细胞机制 胰岛素反应性胸腺细胞。在目标2中，我们将确定早期胸腺抗原暴露对新生儿的影响。 对胰岛抗原有终身耐受性的小鼠。从这些研究中收集的信息可能具有重要的 对我们理解自身反应性T细胞如何逃脱缺失和抗原特异性Treg的影响 发生了发展，导致了建立对胰岛抗原的耐受性的新方法。

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.