The class II region of the major histocompatibility complex (MHC) locus is the main contributor to the genetic susceptibility to type 1 diabetes (T1D). The loss of an aspartic acid at position 57 of diabetogenic HLA-DQβ chains supports this association; this single amino acid change influences how TCRs recognize peptides in the context of HLA-DQ8 and I-Ag7 using a mechanism termed the P9 switch. Here, we built register-specific insulin peptide MHC tetramers to examine CD4+ T cell responses to Ins12-20 and Ins13-21 peptides during the early prediabetic phase of disease in nonobese diabetic (NOD) mice. A single-cell analysis of anti-insulin CD4+ T cells performed in 6- and 12-week-old NOD mice revealed tissue-specific gene expression signatures. TCR signaling and clonal expansion were found only in the islets of Langerhans and produced either classical TH1 differentiation or an unusual Treg phenotype, independent of TCR usage. The early phase of the anti-insulin response was dominated by T cells specific for Ins12-20, the register that supports a P9 switch mode of recognition. The presence of the P9 switch was demonstrated by TCR sequencing, reexpression, mutagenesis, and functional testing of TCRαβ pairs in vitro. Genetic correction of the I-Aβ57 mutation in NOD mice resulted in the disappearance of D/E residues in the CDR3β of anti-Ins12-20 T cells. These results provide a mechanistic molecular explanation that links the characteristic MHC class II polymorphism of T1D with the recognition of islet autoantigens and disease onset.

中文翻译：

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I-Ag7的β57位置控制着NOD小鼠的早期抗胰岛素反应，从而将MHC易感性等位基因与1型糖尿病发作相关联。

主要组织相容性复合体（MHC）基因座的II类区域是导致1型糖尿病（T1D）遗传易感性的主要因素。糖尿病形成的HLA-DQβ链57位天冬氨酸的丢失支持了这种联系；这种单一的氨基酸变化会影响HCR-DQ8和I-Ag7背景下TCR识别肽的方式，该机制称为P9开关。在这里，我们建立了特定于寄存器的胰岛素肽MHC四聚体，以检查非肥胖糖尿病（NOD）小鼠在疾病的糖尿病前期早期对Ins12-20和Ins13-21肽的CD4 + T细胞应答。在6周和12周龄的NOD小鼠中进行的抗胰岛素CD4 + T细胞的单细胞分析揭示了组织特异性基因表达特征。仅在朗格罕岛的胰岛中发现了TCR信号传导和克隆扩增，并产生了经典的TH1分化或异常的Treg表型，与TCR的使用无关。抗胰岛素反应的早期阶段是针对Ins12-20的T细胞所支配的，Ins12-20是支持P9开关识别模式的寄存器。通过TCR测序，再表达，诱变和体外TCRαβ对功能测试证明了P9开关的存在。NOD小鼠中I-Aβ57突变的遗传校正导致抗Ins12-20 T细胞CDR3β中D / E残基的消失。这些结果提供了机械分子解释，将T1D的特征性MHC II类多态性与胰岛自身抗原和疾病发作的识别联系起来。与TCR使用情况无关。抗胰岛素反应的早期阶段是针对Ins12-20的T细胞所支配的，Ins12-20是支持P9开关识别模式的寄存器。通过TCR测序，再表达，诱变和体外TCRαβ对功能测试证明了P9开关的存在。NOD小鼠中I-Aβ57突变的遗传校正导致抗Ins12-20 T细胞CDR3β中D / E残基的消失。这些结果提供了机械分子解释，将T1D的特征性MHC II类多态性与胰岛自身抗原和疾病发作的识别联系起来。与TCR使用情况无关。抗胰岛素反应的早期阶段是针对Ins12-20的T细胞所支配的，Ins12-20是支持P9开关识别模式的寄存器。通过TCR测序，再表达，诱变和体外TCRαβ对功能测试证明了P9开关的存在。NOD小鼠中I-Aβ57突变的遗传校正导致抗Ins12-20 T细胞CDR3β中D / E残基的消失。这些结果提供了机械分子解释，将T1D的特征性MHC II类多态性与胰岛自身抗原和疾病发作的识别联系起来。通过TCR测序，体外表达，诱变和体外TCRαβ对功能测试证明了P9开关的存在。NOD小鼠中I-Aβ57突变的遗传校正导致抗Ins12-20 T细胞CDR3β中D / E残基的消失。这些结果提供了机械分子解释，将T1D的特征性MHC II类多态性与胰岛自身抗原和疾病发作的识别联系起来。通过TCR测序，再表达，诱变和体外TCRαβ对功能测试证明了P9开关的存在。NOD小鼠中I-Aβ57突变的遗传校正导致抗Ins12-20 T细胞CDR3β中D / E残基的消失。这些结果提供了机械分子解释，将T1D的特征性MHC II类多态性与胰岛自身抗原和疾病发作的识别联系起来。