Diabetogenic CD4 T Cell Recognition of Hybrid Peptide Ligands

混合肽配体的致糖尿病 CD4 T 细胞识别

• 批准号: 10247154
• 负责人: SHAODONG DAI
• 金额: $ 51.27万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-09 至 2022-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10247154
• 关键词: Affinity; Amino Acids; Antigens; Area; Aromatic Amino Acids; Autoantigens; Autoimmune Diabetes; Autoimmune Diseases; Autoimmunity; Automobile Driving; Beta Cell; Binding; Biophysics; C-Peptide; C-terminal; CD4 Positive T Lymphocytes; CD8-Positive T-Lymphocytes; Cell Communication; Chromogranin A; Clone Cells; Common Epitope; Complex; Data; Development; Disease; Docking; Epitopes; Goals; Hemorrhage; Human; Human Characteristics; Hybrids; Hyperglycemia; Immune response; Immunotherapy; Inbred NOD Mice; Insulin; Insulin-Dependent Diabetes Mellitus; Islets of Langerhans; Length; Ligands; MHC Class I Genes; MHC Class II Genes; Mammalian Cell; Mediating; Modification; Molecular; Monoclonal Antibodies; Mus; Mutation; N-terminal; Pancreas; Pathogenicity; Pathway interactions; Peptides; Play; Proteins; RNA Splicing; Receptor Activation; Research; Role; Shapes; Specificity; Spottings; Structure; Structure of beta Cell of islet; T cell response; T-Cell Receptor; T-Lymphocyte; T-cell diversity; Testing; Therapeutic; Thymus Gland; Tissues; Variant; autoreactivity; blood glucose regulation; cross reactivity; diabetogenic; granule cell; immunoengineering; in vivo; islet; multicatalytic endopeptidase complex; neoantigens; neoplastic cell; novel; novel therapeutic intervention; novel therapeutics; prevent; prototype; receptor binding; transpeptidation

PROJECT SUMMARY/ABSTRACT The overall goal of this proposal is to understand how diabetogenic T cell receptors (TCRs) recognize the MHCII and hybrid peptide complexes. Peptide ligands of CD4 and CD8 T cells are conventionally derived from contiguous fragments of the parental proteins by the endocytic pathway and proteasome. We first suggested insulin (Ins) B:9-23 and WE14, a natural cleavage product of chromogranin A (ChgA), peptides may be spliced with other beta cell granule proteins and form neo-antigens. We also demonstrated that fusion peptides are the true ligands for many diabetogenic T cells. Both C-terminal modification of the Ins B:9-23 peptide and N- terminal additions to the WE14 peptide of ChgA can create superagonists for T cells. We proposed peptide fusion by transpeptidation as a means of creating the required modifications to the peptides and explain how the T cells driving autoimmunity escape negative selection in the thymus but find their antigen in the target tissue. Our structural and biophysical data showed that the EALYLV portion of Ins B:9-23 and WXRM(D/E) portion of WE14 may be common acceptors of these hybrid peptides. We determined the structures of two different types of mouse TCRs and a human TCR, bound to their optimal versions of the MHCII-Ins peptide ligands. All the Ins reactive TCRs engage the N-terminal portion (EALYL) of Ins B:9-23, indicating similarities in how these ligands are formed in both human and mouse. The structures showed that the specificity differences among mouse Type A and Type B T cells lies in how they interact with the amino acid at p8 (B:21) of the Ins peptide. The structures also show how the peptide modifications were essential to the formation of the complexes, bolstering a role for modification of the peptide in vivo to initiate the CD4 T cell response in T1D. We hypothesize that EALYLV and WXRM(D/E) are the acceptors of the fusion peptides and form the common diabetogenic TCR docking spots, in addition to being novel targets for T1D immunotherapy. Previously, we have shown aromatic amino acids play important role in TCR cross-reactivity. The aromatic amino acids (Y and W) may be the common epitopes for diabetogenic TCRs and critical to shape the broadness of hybrid peptide reactive T cell repertories. Whereas, the donor peptides of hybrid peptides contribute to diversity the T cell repertoire to both Ins and ChgA autoantigens. We will study the following specific aims: Determine how diabetogenic CD4 TCRs recognize IAg7 and ChgA WE14 hybrid peptides; Define the nature of the human Ins B:9-23 hybrid peptides presented to the diabetogenic CD4 TCRs; Test monoclonal antibodies (mAbs) specific for the acceptor portions of the hybrid peptides bound to MHC in the development of T1D. These data may guide therapeutic strategies towards specific modulation of TCR activation, which could be the basis for a novel therapeutic approach in treatment of T1D. Research Strategy Page 2

项目概要/摘要 该提案的总体目标是了解致糖尿病 T 细胞受体 (TCR) 如何识别 MHCII 和杂合肽复合物。 CD4 和 CD8 T 细胞的肽配体通常源自 通过内吞途径和蛋白酶体产生亲本蛋白的连续片段。我们首先建议 胰岛素 (Ins) B:9-23 和 WE14（嗜铬粒蛋白 A (ChgA) 的天然裂解产物），肽可进行剪接 与其他β细胞颗粒蛋白结合并形成新抗原。我们还证明融合肽是 许多致糖尿病 T 细胞的真正配体。 Ins B:9-23 肽的 C 端修饰和 N 端修饰 ChgA WE14 肽的末端添加可以为 T 细胞产生超级激动剂。我们提出了肽 通过转肽融合作为对肽进行所需修饰的一种手段，并解释如何 驱动自身免疫的 T 细胞逃脱了胸腺中的阴性选择，但在靶标中找到了它们的抗原 组织。我们的结构和生物物理数据表明 Ins B:9-23 的 EALYLV 部分和 WXRM(D/E) WE14 的部分可能是这些杂合肽的共同受体。我们确定了两个结构 不同类型的小鼠 TCR 和人类 TCR，与其最佳版本的 MHCII-Ins 肽结合 配体。所有 Ins 反应性 TCR 均与 Ins B:9-23 的 N 端部分 (EALYL) 结合，表明在 这些配体是如何在人和小鼠体内形成的。结构显示特异性差异 小鼠 A 型和 B 型 T 细胞之间的差异在于它们如何与 Ins p8 (B:21) 的氨基酸相互作用 肽。这些结构还表明肽修饰对于形成 复合物，增强了体内肽修饰的作用，以启动 T1D 中的 CD4 T 细胞反应。 我们假设 EALYLV 和 WXRM(D/E) 是融合肽的受体并形成共同的 致糖尿病的 TCR 对接点，也是 T1D 免疫治疗的新靶点。此前，我们 研究表明芳香族氨基酸在 TCR 交叉反应性中发挥重要作用。芳香族氨基酸（Y 和 W) 可能是致糖尿病 TCR 的常见表位，对于塑造杂交的广泛性至关重要 肽反应性T细胞库。然而，杂合肽的供体肽有助于 T 的多样性 Ins 和 ChgA 自身抗原的细胞库。我们将研究以下具体目标： 确定如何 致糖尿病 CD4 TCR 识别 IAg7 和 ChgA WE14 混合肽；定义人类Ins的本质 B：呈递给致糖尿病 CD4 TCR 的 9-23 杂合肽；测试单克隆抗体 (mAb) 特异性 用于 T1D 发展过程中与 MHC 结合的杂合肽的受体部分。这些数据可能 指导针对 TCR 激活的特定调节的治疗策略，这可能是 治疗 T1D 的新方法。 研究策略第2页