Molecular Dissection of Insulin Targeting in Anti-Islet Autoimmunity

描述（由申请人提供）：主要组织相容性复合体（MHC） II类位点与1型糖尿病的风险密切相关，自身免疫引起糖尿病的组织特异性可能由MHC分子、抗原和T细胞受体（TCR）组成的三分子复合体决定。我们假设这种三分子复合物的成分之间的相互作用，所有这些成分都在种系中编码，决定了参与1型糖尿病发展的T细胞的性质。在自发性糖尿病动物模型NOD小鼠中，靶向胰岛素B链9-23氨基酸肽（胰岛素B:9-23）很可能是胰岛炎症启动的重要决定因素。我们最近发现含有种系编码可变基因（Vgene）序列“TRAV5D-4”的tcr通过识别胰岛素B:9-23肽在诱导抗胰岛自身免疫中起关键作用。因此，由胰岛素B:9-23肽和TRAV5D-4 TCR α链组成的三分子复合物在抗胰岛自身免疫中起关键作用；然而，表达TRAV5D-4 TCRs的T细胞如何参与疾病的发生和发展仍有待阐明。给定证据表明DQ8糖尿病易感HLA二类分子的直接同源点头I-Ag7呈现胰岛素B:合唱肽,T细胞表达TRAV13-1(人类直接同源TRAV5D-4)细胞受体α链主要存在于1型糖尿病患者的胰腺DQ8,这个提议的最终目标是验证一个概念证明胰岛素targetig通过特定germline-encoded TCR Vgene主题胰岛自身免疫的发展起着至关重要的作用。在本研究中，我们的目标是利用NOD小鼠模型确定tcr，特别是那些含有TRAV5D-4的tcr如何靶向关键肽胰岛素B:9-23，从而启动胰岛炎症的分子机制（目的1），并确定表达TRAV5D-4的T细胞是否对NOD小鼠的糖尿病发展至关重要（目的2）。如果在缺乏tra5d -4的情况下，抗胰岛自身免疫的发展被完全抑制，那么仅针对表达这些必需TRAV基因的T细胞，将使我们能够开发出一种副作用最小的强大免疫疗法。最后，我们将提出一个假设，即在人类1型糖尿病易感性的基础上，由胰岛素B:9-23肽和TRAV13-1 TCR Vgene基序组成的人类三分子复合物中存在概念上类似的相互作用（目的3）。本研究的发现将为通过胰岛素三分子相互作用引发胰岛自身免疫的原理提供更深入的理解

DESCRIPTION (provided by applicant): The major histocompatibility complex (MHC) class II locus is strongly associated with the risk of type 1 diabetes, and tissue specificity of the autoimmunity causing diabetes is likely to be determined by the trimolecular complex composed of an MHC molecule, an antigen, and a T cell receptor (TCR). We hypothesize that the interactions between components of this trimolecular complex, all of which are encoded in the germline, determines the nature of T cells involved in the development of type 1 diabetes. Targeting of an insulin B chain 9-23 amino acid peptide (insulin B:9-23) is highly likely to be an essential determinant in the initiation of islet inflammation in the spontaneous diabetes animal model, NOD mouse. We recently discovered that TCRs containing the germline-encoded variable gene (Vgene) sequence called "TRAV5D-4" play a critical role to induce anti-islet autoimmunity via the recognition of insulin B:9-23 peptide. Thus, the trimolecular complex consisting of the insulin B:9-23 peptide and TRAV5D-4 TCR alpha chain plays a key role in developing anti-islet autoimmunity; however, how T cells expressing TRAV5D-4 TCRs contribute to the initiation and development of the disease remains to be elucidated. Given evidence that the DQ8 diabetes- susceptible HLA class II molecule is an ortholog of NOD I-Ag7 presenting the insulin B:9-23 peptide and that T cells expressing TRAV13-1 (human ortholog of TRAV5D-4) TCR alpha chains dominantly exist in the pancreas of a type 1 diabetes patient having DQ8, the ultimate goal of this proposal is to verify a proof of concept that insulin targetig by a specific germline-encoded TCR Vgene motif plays a critical role in the development of islet autoimmunity. In this proposal, we aim to determine the molecular mechanism of how TCRs, in particular those containing TRAV5D-4, target the critical peptide, insulin B:9-23, to initiate isle inflammation using the NOD mouse model (Aim 1), and to determine whether T cells expressing TRAV5D-4 are essential for diabetes development in NOD mice (Aim 2). If the development of anti-islet autoimmunity is completely suppressed in the absence of TRAV5D-4, targeting only T cells expressing such essential TRAV genes will enable us to develop a robust immunotherapy with the minimum of side effects. Finally, we will pursue the hypothesis that there is a conceptually similar interaction in the human trimolecular complex consisted of the insulin B:9-23 peptide and TRAV13-1 TCR Vgene motif underlying susceptibility to human type 1 diabetes (Aim 3). Findings from this proposal will provide a deeper understanding of the principles underlying the initiation of islet autoimmunity via the interaction within the insulin trimolecular complex, which will ultimately to be applied to design antigen-based immunodiagnostic and immunotherapeutic clinical studies for type 1diabetes in humans.