Tolerogenic Immune Modifying Nanoparticles Encapsulating Multiple Recombinant Pancreatic β Cell Proteins Prevent Onset and Progression of Type 1 Diabetes in NOD Mice

Type 1 diabetes (T1D) is an autoimmune disease characterized by T and B cell responses to proteins expressed by insulin-producing pancreatic β cells, inflammatory lesions within islets (insulitis), and β cell loss. We previously showed that antigen (Ag)-specific tolerance targeting single β cell protein epitopes is effective in preventing T1D induced by transfer of mono-specific diabetogenic CD4 and CD8 transgenic T cells to NOD. scid mice. However, tolerance induction to individual diabetogenic proteins, e.g., GAD65 or insulin, has failed to ameliorate T1D both in wildtype NOD mice and in the clinic. Initiation and progression of T1D is likely due to activation of T cells specific for multiple diabetogenic epitopes. To test this hypothesis, recombinant insulin, GAD65, and chromogranin A proteins were encapsulated within poly(lactic- co -glycolic acid) (PLGA) nanoparticles (COUR CNPs) to assess regulatory T cell induction, inhibition of Ag-specific T cell responses, and blockade of T1D induction/progression in NOD mice. While treatment of NOD mice with CNPs containing a single protein inhibited the corresponding Ag-specific T cell response, inhibition of overt T1D development only occurred if all three diabetogenic proteins were included within the CNPs (CNP-T1D). Blockade of T1D following CNP-T1D tolerization was characterized by regulatory T cell induction and a significant decrease in both peri-insulitis and immune cell infiltration into pancreatic islets. As we have recently published that CNP treatment is both safe and induced Ag-specific tolerance in a Phase 1/2a celiac disease clinical trial, Ag-specific tolerance induced by nanoparticles encapsulating multiple diabetogenic proteins is a promising approach to T1D treatment.