Type 1 diabetes (T1D) results from autoimmune destruction of insulin-producing pancreatic β cells, involving CD4⁺ and CD8⁺ T cells. Non-obese diabetic (NOD) mice are a model for human T1D. As islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP) is a major diabetogenic antigen in NOD mice, we developed a model to test IGRP antigen-specific immunotherapy. We showed previously that liposomes co-encapsulating antigen and NF-kB inhibitor induced antigen-specific suppression of CD4⁺ T cells in mice. These liposomes passively target and deliver their payload to dendritic cells in lymphoid organs, suppressing NF-kB activation.

For the current model, we injected NOD mice with liposomes co-delivering IGRP_206-214 peptide and NF-kB inhibitor. Twenty four hours after liposome injection to naïve mice, we observed uptake of liposomes specifically by antigen presenting cells (APCs). Delivered peptide was presented by these APCs as CTV-labelled IGRP-specific CD8⁺ T cells proliferated in draining lymph nodes after subcutaneous delivery of liposomes co-encapsulating IGRP_206-214 and the NF-kB inhibitor calcitriol. After adoptive transfer of IGRP-specific CD8⁺ T cells, we enumerated both adoptively-transferred and endogenous antigen-specific T cells using K^d-IGRP tetramers, and measured IFN-g production by intracellular staining ex vivo. Following liposome treatment, transferred IGRP-specific CD8⁺ T cells expanded at day 4 and contracted by day 10. IFN-g production was decreased in IGRP-specific CD8⁺ T cells in mice that received peptide and calcitriol containing liposomes. In an accelerated transfer model of diabetes, liposome treatment was able to significantly delay the onset of diabetes.

These data establish a model in NOD mice for analysis of diabetogenic antigen presentation and response to antigen-specific liposome immunotherapy to complement studies of immunotherapy to prevent or treat diabetes.