3023-LB: Dose Effect of Proinsulin mRNA LPAs on Diabetes Development in the NOD Mouse Model

Introduction and Objective: In type 1 diabetes (T1D), immunomodulation may suppress autoimmunity and prevent β-cell depletion. We aimed to evaluate the dose-dependent effects of proinsulin II (PI2) mRNA lipid particle aggregates (LPAs) on diabetes development in the non-obese diabetic (NOD) mouse model. Methods: After in vitro transcription, murine mRNA was loaded into lipid particles with a 1:1 RNA:LPA ratio. At 8 weeks of age female NOD/ShiLtJ mice (Jackson Laboratory) received intravenous mRNA LPA injections with 50 μg, 25 μg, 12.5 μg, or 6.125 μg of PI2 mRNA (6 doses total) or left untreated (n=15/group). Mice were monitored weekly for diabetes (glucose ≥ 250 mg/dl on two consecutive days) until endpoint. Kaplan Meier survival curves and log-rank tests were used to compare T1D rates. Unpaired t-tests were used to evaluate differences in lymphocytes and chemokines six hours post dose. Results: At 32 weeks, the diabetes rates were 40% in 6.125 μg group, 73.3% in 12.5 μg, 25 μg, 50 μg groups, and 86.7% in untreated (Figure 1a). Lymphocyte and chemokine counts were obtained 6 hours post dose (Figure 1b-e). Conclusion: Lower doses of mRNA LPAs significantly delay T1D onset and reduce incidence compared to untreated mice and mice with higher doses. The post-treatment decrease in lymphocytes is abrogated at lower doses. Low dose mRNA LPAs maintain immunoregulatory cytokine elevations with reduced proinflammatory cytokines compared to higher doses, which may favor induction of immunotolerance. Disclosure C.M. Kelly: None. M.J. Haller: Advisory Panel; Current; MannKind Corporation, Sanofi, SAB Biotherapeutics, Inc. C. Wasserfall: None. T. Foster: None. Funding National Institutes of Health (K12DK133995)