抗原特异性单克隆抗体治疗1型糖尿病及其机制的研究

Type 1 Diabetes (T1DM) is a CD4 T cell mediated autoimmune disease characterized by destruction of pancreatic β cells. Currently there is no cure for T1DM. In contrast to other whole immune system affected therapies such as Cyclosporine A and antithymocyte globulin, antigen specific immunotherapies are likely to be safer and more effective for treatment of T1DM. Considerable evidence now indicates that insulin B chain amino acid 9 to 23, B:9-23 peptide, is a key autoantigen epitope of T1DM in both spontaneous T1DM mice and in humans as well. B:9-23 peptides can bind to MHC class II molecule (MHC II) in different positions, termed registers. We have recently reported that the insulin B:9-23 peptide becomes an auto-antigen when it binds to MHC II molecule in register 3, and CD4+ T cells can be activated by the complex of B:9-23/MHC II with peptide presented in register 3. We hypothesized that the presentation of insulin B:9-23 can be blocked by a monoclonal antibody (mAb)targeting the B:9-23/MHC II complex, and consequently insulitis can be suppressed and diabetes will be inhibited. To test our hypothesis, we then generated a B:9-23/MHC II specific mAb, named mAb287. As expected, mAb287 significantly suppressed the development of insulitis and delayed or prevented the development of T1DM in a spontaneous T1DM mouse model. Thus, we validated proof-of-concept that a mAb specific for the B:9-23/ MHC II presentation complex with B:9-23 in a pathogenic register is able to reprogram the progress of islet autoimmunity and modulate the development of T1DM...Given the success of anti-B:9-23/MHC II antibody in preventing T1DM in mouse model, here we propose to explore the molecular mechanisms underlying the diabetes protection of mAb287. We will investigate the changes of numbers, frequencies and functions of antigen presenting cells, insulin specific and other islet autoantigens specific T cells, such as Chromogranin reactive T cells, and evaluate the balance between the diabetogenic effective T cells and regulatory T cells. In the meanwhile, we will produce a new monoclonal antibody targeting human B:9-23/MHC II complex, and test its ability to inhibit insulin reactive inflammatory CD4 T cell clones isolated from T1DM patients. ..Our final goal is to develop a class of safe antigen specific therapeutic antibodies to reprogram the process of islet autoimmunity to prevent or reverse Type 1 Diabetes in human. This project will provide solid pre-clinical data and useful mechanistic knowledge for applying anti-insulin/MHC II antibodies in clinical trials in the near future.

1型糖尿病（T1DM）是T细胞介导的胰岛β细胞特异性自身免疫性疾病。抗原特异性免疫干预的方法可望安全、有效地治疗T1DM。胰岛素B链9-23氨基酸肽段（B：9-23）是小鼠和人共同的重要抗原表位。我们前期研究表明B:9-23以弱亲和力的第三种方式（register 3）结合在MHC II 分子抗原槽内，形成B:9-23/MHC II 复合物，激活T细胞进而引起胰岛自身炎症。胰岛素B:9-23/MHC II 复合蛋白形成的胰岛素构象表位是T1DM的致病性抗原表位。我们研发了首个B:9-23/MHC II抗原表位特异性单抗（mAb287），并证明了mAb287具有抑制胰岛炎症，减少或阻止T1DM发生的作用。本研究在已有基础上，探讨mAb287干预糖尿病发生发展的分子细胞机制；研发抗人胰岛素构象表位单抗，并检测其抑制自身免疫细胞的作用。本项目为用抗原单抗治疗T1DM提供理论依据及候选抗体。