3016-LB: Overexpression of Immune Inhibitory Ligand B7-H4, Not PD-L1, on Pancreatic Beta Cells Confer Resistance to Type 1 Diabetes in NOD Mice

Introduction and Objective: Type 1 Diabetes (T1D) results from destruction of pancreatic β cells by autoreactive T cells. Modulating immune inhibitory pathways in the pancreatic islet may limit auto-reactive T cells and confer resistance to T1D disease. This study evaluated whether over-expression of immune inhibitory ligands B7-H4 and PD-L1 in pancreatic β cells can protect against T1D in non-obese diabetic (NOD) mouse model. Methods: Transgenic NOD mice expressing B7-H4 or PD-L1 restricted to β cells via the mouse insulin 2 promoter were generated using pronuclear injection; referred to as NODB7H4 and NODPDL1 respectively. Female transgenic NOD mice were monitored weekly for diabetic incidence until 30 weeks of age, defined as two consecutive readings of non-fasting glucose ≥250 mg/dl. Disease incidence was evaluated using Kaplan Meier curves and log-rank tests. Pancreatic islet and immune cells were profiled were conducted during peak of insulitis (~12 weeks of ages) using single cell RNA sequencing (scRNAseq) and flow cytometry and compared to wild type litter mate controls (NODWT). Results: NODB7H4 mice exhibited significantly reduced diabetic incidence (2/20 mice; p=0.002 vs. NODWT), while NODPDL1 mice did not exhibit delayed T1D onset. Immune phenotyping revealed a reduction of activated effector CD8+ T cells (defined by the co-expression of CD39 and PD-1) in the pancreas of NODB7H4 mice; an effect not observed in NODPDL1 mice. Additionally, the reduction of diabetic incidence in NODB7H4 was associated with transcriptional downregulation of immune response related pathways in β cells, indicating a less immune activated environment overall. Conclusion: Over-expression of B7H4, not PD-L1, on β cells suppress autoreactive T cells and protects against T1D in NOD mouse models. Enhancing B7-H4 expression on β cells or targeting related immune pathways may offer novel potential therapeutic strategies for T1D. Disclosure O. Weizman: Employee; Current; Regeneron Pharmaceuticals Inc. Q. Su: Employee; Current; Regeneron Pharmaceuticals Inc. Stock/Shareholder; Current; Regeneron Pharmaceuticals Inc. R.E. Bucktrout: Employee; Current; Regeneron Pharmaceuticals Inc. B. Sung: None. J. Kim: Employee; Current; Regeneron Pharmaceuticals Inc. T. Kehrer: Employee; Current; Regeneron Pharmaceuticals Inc. C. Hunt: None. N. Oristian: None. J. Golubov: Employee; Current; Regeneron Pharmaceuticals Inc. C. Lett: None. W. Lim: Employee; Current; Regeneron Pharmaceuticals Inc. A. Le Floc'h: Employee; Current; Regeneron Pharmaceuticals Inc. J.M. Orengo: Employee; Current; Regeneron Pharmaceuticals Inc. Stock/Shareholder; Current; Regeneron Pharmaceuticals Inc. Other - Officer of Regeneron pharmaceuticals; Current; Regeneron Pharmaceuticals Inc. D. Skokos: Employee; Current; Regeneron Pharmaceuticals Inc. B. Wang: Employee; Current; Regenacy Pharmaceuticals, Inc.