Insulin specific T cell response shaped by diabetes protective MHC class II molecules

项目摘要 许多自身免疫性疾病的易感性或保护性的主要遗传决定因素存在于 人类主要组织相容性复合体(MHC)，包含人类白细胞抗原(HLA)区域。输入文字 1糖尿病(T1D)，特别是人类白细胞抗原II类等位基因(如DR4/DQ8)增加了疾病的发生风险， 而其他的(如DQ6、DQB1*06：02)则导致显性保护。MHC II类分子的功能是呈现 经处理的抗原作用于T细胞，与MHC-II类−多肽−T细胞受体(TCR)形成三分子复合体 涉及自身免疫中形成自身反应性T细胞反应的自体肽的呈递。的目标是 我们的研究旨在弥合对糖尿病具有保护作用的MHC-II类分子和胰岛素专一性知识的空白。 T细胞反应。 上一次资助期间的数据表明，T1D保护性MHC II类分子(小鼠IAb≈人 DQ6)提供胰岛素，特别是胰岛素B链氨基酸9-23(B：9-23)，以激活CD4T细胞 调节表型(Tregs)。在NOD小鼠自发性自身免疫性糖尿病模型中，胰岛素特异性 存在Foxp3+Treg，但不能预防糖尿病的发生。除NOD糖尿病外还有IAB的存在 授予IAg7 MHC II类药物可阻止所有糖尿病的发生。每个上都有荧光B：9-23四聚体 II类分子，我们能够在胰腺淋巴中检测到B：9-23/IAb 1型调节性T细胞(TR1细胞) NOD小鼠结节中存在IAb/IAg7杂合子，而胰岛素-IAg7 T细胞频率较低且未被激活。 同样，在患有DQ6的非糖尿病人中，我们能够从外周血中增殖Tregs 对胰岛素B的反应：9-21/DQ6。对这些增殖的胰岛素树的单细胞RNA测序显示了一个明显的 分泌抗炎细胞因子IL-10的TR1簇。然而，这些胰岛素树的必要性和 这些细胞赋予糖尿病抵抗力的机制仍有待确定。在具体目标1中，我们将 确定胰岛素树预防糖尿病发生的分子表型和必要性 具有抗糖尿病MHC II类分子的小鼠模型。具体目标2侧重于#年的平行研究 人类识别限制在DQ6和DQ8的胰岛素树的保护功能 并且没有T1D。这一提议的成功完成将为我们提供对功能和分子的洞察力 胰岛素树突状细胞与糖尿病保护性MHC-II类分子的表型及其直接关系的研究 在赋予糖尿病保护方面的作用，从而帮助设计可能改善Treg功能的治疗方法 T1D中潜在的自身免疫。

Project Summary The major genetic determinant in susceptibility to or protection from many autoimmune diseases reside in the human major histocompatibility complex (MHC) that contains the human leukocyte antigen (HLA) region. In type 1 diabetes (T1D), particular HLA class II alleles (e.g. DR4/DQ8) increase the risk for developing disease, whereas others (e.g., DQ6, DQB1*06:02) lead to dominant protection. MHC class II molecules function to present processed antigens to T cells, and the MHC class II−peptide−T cell receptor (TCR) forms a trimolecular complex involving the presentation of self-peptides that shape autoreactive T cell responses in autoimmunity. The goal of our studies is to bridge the gap of knowledge in diabetes-protective MHC class II molecules and insulin-specific T cell responses. Data from the last funding period indicates that T1D protective MHC class II molecules (murine IAb ≈ human DQ6) present insulin, and specifically insulin B chain amino acids 9-23 (B:9-23) to activate CD4 T cells with a regulatory phenotype (Tregs). In the NOD mouse model of spontaneous autoimmune diabetes, insulin-specific FoxP3+ Tregs are present but fail to prevent diabetes onset. The presence of IAb in addition to the NOD diabetes conferring IAg7 MHC class II abrogates all diabetes development. With fluorescent B:9-23 tetramers on each class II molecule, we are able to detect B:9-23/IAb type 1 regulatory T cells (Tr1 cells) in the pancreatic lymph nodes in NOD mice heterozygous for IAb/IAg7, while insulin-IAg7 T cells are less frequent and not activated. Similarly in non-diabetic humans with DQ6, we are able to proliferate Tregs from the peripheral blood that respond to insulin B:9-21/DQ6. Single cell RNA sequencing of these proliferated insulin-Tregs reveals a distinct Tr1 cluster that secrete the anti-inflammatory cytokine, IL-10. However, the necessity for these insulin-Tregs and mechanisms by which these cells confer diabetes resistance remains to be determined. In specific aim 1, we will determine the molecular phenotype and necessity for insulin-Tregs to protect against diabetes development in murine models with a diabetes-resistant MHC class II molecule. Specific aim 2 focuses on parallel studies in humans to identify the protective features of insulin-Tregs restricted to DQ6 and those to DQ8 in individuals with and without T1D. The successful completion of this proposal will provide insights into the function and molecular phenotype of insulin-Tregs restricted to diabetes-protective MHC class II molecules and determine their direct role in conferring diabetes protection, thus aiding the design of therapies that may improve Treg function to treat the underlying autoimmunity in T1D.