Over the past four decades, the number of people with Type 1 Diabetes (T1D) has increased by 4% per year, making it an important public health challenge. Currently, no curative therapy exists for T1D and the only available treatment is insulin replacement. HLA-DQ8 has been shown to present antigenic islet peptides driving the activation of CD4⁺ T-cells in T1D patients. Specifically, the insulin peptide InsB:9-23 activates self-reactive CD4⁺ T-cells, causing pancreatic beta cell destruction. The aim of the current study was to identify retro-inverso-d-amino acid based peptides (RI-D-peptides) that can suppress T-cell activation by blocking the presentation of InsB:9-23 peptide within HLA-DQ8 pocket. We identified a RI-D-peptide (RI-EXT) that inhibited InsB:9-23 binding to recombinant HLA-DQ8 molecule, as well as its binding to DQ8 expressed on human B-cells. RI-EXT prevented T-cell activation in a cellular antigen presentation assay containing human DQ8 cells loaded with InsB:9-23 peptide and murine T-cells expressing a human T-cell receptor specific for the InsB:9-23–DQ8 complex. Moreover, RI-EXT blocked T-cell activation by InsB:9-23 in a humanized DQ8 mice both ex vivo and in vivo, as shown by decreased production of IL-2 and IFN-γ and reduced lymphocyte proliferation. Interestingly, RI-EXT also blocked lymphocyte activation and proliferation by InsB:9-23 in PBMCs isolated from recent onset DQ8-T1D patients. In summary, we discovered a RI-D-peptide that blocks InsB:9-23 binding to HLA-DQ8 and its presentation to T-cells in T1D. These findings set the stage for using our approach as a novel therapy for patients with T1D and potentially other autoimmune diseases.

在过去的四年中，1 型糖尿病 (T1D) 的人数以每年 4% 的速度增长，这使其成为一项重要的公共卫生挑战。目前，T1D 尚无治愈性疗法，唯一可用的疗法是胰岛素替代疗法。HLA-DQ8 已显示呈递抗原性胰岛肽，驱动T1D 患者的 CD4 ⁺ T 细胞活化。具体来说，胰岛素肽 InsB:9-23 会激活自身反应性 CD4 ⁺ T 细胞，导致胰腺 β 细胞破坏。当前研究的目的是确定复古inverso- d-基于氨基酸的肽（RI-D-肽），可通过阻断 HLA-DQ8 口袋内 InsB:9-23 肽的呈递来抑制 T 细胞活化。我们鉴定了一种 RI-D-肽 (RI-EXT)，它抑制 InsB:9-23 与重组 HLA-DQ8 分子的结合，以及它与人 B 细胞上表达的 DQ8 的结合。RI-EXT 在细胞抗原呈递试验中阻止 T 细胞活化，该试验包含装载有 InsB:9-23 肽的人 DQ8 细胞和表达对 InsB:9-23-DQ8 复合物具有特异性的人 T 细胞受体的鼠 T 细胞。此外，RI-EXT 在体外和体内都阻断了 InsB:9-23 人源化 DQ8 小鼠中 T 细胞的激活，如IL-2和IFN-γ的产生减少以及淋巴细胞增殖减少所示。有趣的是，RI-EXT 还通过 InsB:9-23 在从最近发病的 DQ8-T1D 患者中分离的 PBMC 中阻断了淋巴细胞的激活和增殖。总之，我们发现了一种 RI-D 肽，可以阻止 InsB:9-23 与 HLA-DQ8 的结合及其在 T1D 中向 T 细胞的呈递。这些发现为使用我们的方法作为 T1D 和其他潜在自身免疫性疾病患者的新疗法奠定了基础。