Molecular Dissection of Insulin Targeting in Anti-Islet Autoimmunity

描述（申请人提供）：主要组织相容性复合体（MHC）II类基因座与1型糖尿病的风险密切相关，导致糖尿病的自身免疫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组分之间的相互作用，所有这些都是在种系中编码的，决定了参与1型糖尿病发展的T细胞的性质。靶向胰岛素B链9-23氨基酸肽（胰岛素B：9-23）很可能是自发性糖尿病动物模型NOD小鼠中胰岛炎症起始的重要决定因素。我们最近发现，含有称为“TRAV 5D-4”的种系编码的可变基因（Vgene）序列的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TRAV 5D-4 TCR α链组成的三分子复合物在发展抗胰岛自身免疫中起关键作用;然而，表达TRAV 5D-4 TCR的T细胞如何促进疾病的起始和发展仍有待阐明。考虑到DQ 8糖尿病易感性HLA II类分子是呈递胰岛素B：9-23肽的NOD I-Ag 7的直系同源物以及表达TRAV 13 -1（TRAV 5D-4的人直系同源物）TCR α链的T细胞主要存在于具有DQ 8的1型糖尿病患者的胰腺中的证据，该提议的最终目标是验证通过特定种系编码的TCR V基因基序靶向胰岛素在胰岛自身免疫的发展中起关键作用的概念证明。在该提议中，我们的目标是确定TCR（特别是含有TRAV 5D-4的TCR）如何靶向关键肽胰岛素B：9-23以使用NOD小鼠模型引发胰岛炎症的分子机制（目标1），并确定表达TRAV 5D-4的T细胞是否是NOD小鼠中糖尿病发展所必需的（目标2）。如果在TRAV 5D-4不存在的情况下，抗胰岛自身免疫的发展被完全抑制，则仅靶向表达这些必需TRAV基因的T细胞将使我们能够开发具有最小副作用的稳健免疫疗法。最后，我们将继续研究在由胰岛素B：9-23肽和TRAV 13 -1 TCR V基因基序组成的人三分子复合物中存在概念上相似的相互作用的假设，该复合物是人1型糖尿病易感性的基础（目的3）。本研究的发现将使我们更深入地了解通过胰岛素三分子内的相互作用引发胰岛自身免疫的原理 复合物，这将最终应用于设计基于抗原的免疫诊断和免疫学临床研究，为1型糖尿病在人类。

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.