73-OR: Loss of NADPH Oxidase–Derived Superoxide Impairs Autoreactive T Cell Trafficking into Islets to Delay Type 1 Diabetes Development

Type 1 diabetes (T1D) and β-cell destruction is mediated by proinflammatory cytokines, reactive oxygen species (ROS) , and immune cells. NADPH oxidase (NOX) -derived superoxide, a precursor for many ROS, regulate cell signaling, cellular differentiation, survival, and autoimmune responses in T1D. We previously discovered that NOX-derived superoxide promote chemokine synthesis and skew macrophages and T cells towards a proinflammatory response in T1D. Yet, it remains unknown if NOX is necessary for diabetogenic T cell trafficking into islets. Using non-obese diabetic (NOD) mice lacking NOX-derived superoxide (NOD.Ncf1^m1J) , we tested the hypothesis that loss of NOX-derived superoxide delays T1D by impairing autoreactive T infiltration into islets. Female NOD.Ncf1^m1J mice (n=20) had a significant delay in spontaneous T1D development, as only 20% became diabetic by 40-weeks of age compared to 90% NOD mice (n=23) . Flow cytometry analysis of 12-week-old NOD.Ncf1^m1J mice revealed a significant reduction in pancreatic CD4 T cells expressing CD69⁺ (5.5-fold) , CCR2⁺ (1.9-fold) and CCR5⁺ (2.1-fold) compared to NOD. NOD.Ncf1^m1J islets also had significantly fewer total CD4⁺ T cells (1.8-fold) , CD25⁺ CD4⁺ T cells (2.0-fold) , naïve CD4⁺ T cells (2.0-fold) , and effector CD4⁺ T cells (2.2-fold) compared to NOD. Utilizing tetramer staining to identify autoreactive T cells, we observed a significant reduction in NOD.Ncf1^m1J islet-infiltrating CD4⁺ T cells specific for insulin (Ins) (2.6-fold) , Ins-chromogranin A hybrid peptide (HIP) (3.0-fold) , and Ins-islet amyloid polypeptide HIP (2.6-fold) compared to NOD. Our findings provide evidence that loss of NOX-derived superoxide can impair autoreactive T cell activation and islet-infiltration as a possible mechanism to delay T1D development. Future studies will determine if NOX regulates islet chemokine synthesis to mediate autoreactive T infiltration into islets.