Expansion of GAD65–Specific Immunoregulatory Effector Cells by Biolistic-Mediated Gene Delivery Prevents Autoimmune Diabetes in NOD Mice (131.14)

Abstract

Abstract Intramuscular (i.m.) vaccination with plasmid DNA (pDNA) encoding beta cell autoantigens such as glutamic acid decarboxylase 65 (GAD65) is an approach to suppress ongoing Type 1 diabetes (T1D) in NOD mice. However, protection is dependent on co-treatment with pDNAs encoding IL-4 and/or IL-10, and the subsequent induction of type 2 CD4+ T effectors. To enhance the therapeutic efficacy of pDNA vaccination, we explored epidermal delivery of pDNA via “gene gun”. Notably, reports have shown induction of a preferential type 2-like CD4+ T cell response when pDNA encoding antigen-only is delivered to the epidermis via gene gun. We hypothesized that biolistic delivery of pDNA would preferentially induce type 2 CD4+ T effectors and suppress established beta cell autoimmunity in NOD mice. Groups of 10 wk-old NOD female mice were treated four times with pDNA encoding GAD65-Ig (pGAD65) administered i.m. or delivered by gene gun on 1.6 uM gold particles. Whereas i.m. injection of pGAD65 resulted in preferential induction of GAD65-specific CD4+ Th1 cells and no protection against T1D, the majority of NOD mice treated with gene gun delivered pGAD65 remained diabetes-free and protection correlated with increased GAD65-specific IL-4 secreting CD4+ T cells. These results demonstrate that gene-gun delivered pDNA encoding beta cell autoantigen-only is an effective strategy to induce immunoregulatory CD4+ T cells and suppress T1D.