The Role of Aire in the selection of Regulatory T cells in Diabetes

Abstract

Abstract In autoimmune diseases like T1D, it is proposed that failure in central tolerance mechanisms towards pancreatic islet self-antigens leads to the escape of pathogenic clones and loss of critical immunosuppressive antigen-specific Tregs. The importance of Aire in maintaining central tolerance against self-reactive antigens is evidenced by the multiorgan autoimmune disease seen in individuals with mutation the Aire gene. When Aire-expression is specifically ablated in mouse mTECs, there is a dramatic increase in the number of self-reactive T cells that escape negative selection, in addition, a dramatic loss of Tregs. Utilizing novel high-throughput platforms and single-cell DNA barcoding technology has allowed us to assess several thousand CD4+ T-cell clones. The use of FoxP3-GFP reporter mice permits us to identify individual Tregs that have undergone Aire-dependent selection in the thymus and compare the TCR repertoire to mice that have had Aire specifically ablated from the mTECs. Identification of unique clones and gene signatures within our large datasets has allowed us to start to qualitatively assess the functional role of the identified TCRs within the model of T1D. We have begun comparisons of our extensive datasets to insulin-specific TCRs and TCRs that we have previously identified from diabetic animals. In addition, the peptide specificities of the identified TCRs are being evaluated using Baculovirus MHC-II peptide libraries. Our proposed study aims to expand our knowledge on TCR repertoire of Aire-dependent Tregs and the antigen-specificity in T1D, improving our understanding of the respective function of thymic-derived antigen-specific Treg suppression in peripheral tissues associated with autoimmune T1D.