An altered CD8+ T cell epitope of insulin prevents type 1 diabetes in humanized NOD mice.

Autoreactive CD8+ T cells, which play an indispensable role in β cell destruction, represent an emerging target for the prevention of type 1 diabetes (T1D). Altered peptide ligands (APLs) can efficiently induce antigen-specific T cells anergy, apoptosis or shifts in the immune response. Here, we found that HLA-A*0201-restricted CD8+ T cell responses against a primary β-cell autoantigen insulin epitope InsB15-14 were present in both NOD.β2mnull.HHD NOD mice and T1D patients. We generated several APL candidates for InsB15-14 by residue substitution at the p6 position. Only H6F exhibited an inhibitory effect on mInsB15-14-specific CD8+ T cell responses in vitro. H6F treatment significantly reduced the T1D incidence, which was accompanied by diminished autoreactive CD8+ T cell responses to mInsB15-14, inhibited infiltration of CD8+ and CD4+ T cells in the pancreas and reduced pro-inflammatory cytokine production in pancreatic and splenic T cells in NOD.β2mnull.HHD mice. Mechanistically, H6F treatment significantly augmented a tiny portion of CD8+CD25+Foxp3+ T cells in the spleen and especially in the pancreas. This subset exhibited typical Treg phenotypes and required peptide-specific restimulation to exert immunosuppressive activity. Therefore, this APL H6F may be a promising candidate with potential clinical application value for antigen-specific prevention of T1D.