Objective: Type 1 diabetes can be inhibited in standard NOD mice by autoantigen-specific immunotherapy targeting pathogenic CD8+ T-cells. NOD.β2m(null).HHD mice expressing human HLA-A2.1 but lacking murine major histocompatibility complex class I molecules develop diabetes characterized by CD8 T-cells recognizing certain autoantigenic peptides also targeted in human patients. These include peptides derived from the pancreatic β-cell proteins insulin (INS1/2 A(2-10) and INS1 B(5-14)) and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP(265-273) and IGRP(228-236)). Hence, NOD.β2m(null).HHD mice represent a model system for developing potentially clinically translatable interventions for suppressing diabetogenic HLA-A2.1-restricted T-cell responses.
Research design and methods: Starting at 4-6 weeks of age, NOD.β2m(null).HHD female mice were injected intravenously with syngeneic splenocytes to which various admixtures of the four above-mentioned peptides were bound by the cross-linking agent ethylene carbodiimide (ECDI).
Results: Treatment with such cells bearing the complete cocktail of INS and IGRP epitopes (designated INS/IGRP-SPs) significantly inhibited diabetes development in NOD.β2m(null).HHD recipients compared with controls receiving splenocytes coupled with an irrelevant HLA-A2.1-restricted Flu16 peptide. Subsequent analyses found syngeneic splenocytes bearing the combination of the two ECDI-coupled IGRPs but not INS peptides (IGRP-SPs or INS-SPs) effectively inhibited diabetes development in NOD.β2m(null).HHD mice. This result was supported by enzyme-linked immunospot (ELISPOT) analyses indicating combined INS/IGRP-SPs diminished HLA-A2.1-restricted IGRP but not INS autoreactive CD8+ T-cell responses in NOD.β2m(null).HHD mice.
Conclusions: These data support the potential of a cell therapy approach targeting HLA-A2.1-restricted IGRP autoreactive CD8 T-cells as a diabetes intervention approach in appropriate human patients.