NADPH oxidase-derived superoxide promote autoreactive T cell infiltration into islets of prediabetic NOD mice.

Abstract

Abstract Proinflammatory cytokines, reactive oxygen species (ROS), and T cells contribute to β-cell destruction in Type 1 diabetes (T1D). NADPH oxidase (NOX) generate superoxide, a precursor for a variety of ROS, regulate cell survival, differentiation, signaling, and autoimmune responses in T1D. Previously, we demonstrated that NOX-derived superoxide increase chemokine synthesis and skew macrophages and T cells towards an inflammatory response in T1D. However, it is unclear if NOX is required for diabetogenic T cell trafficking to islets. Using non-obese diabetic (NOD) mice deficient in NOX-derived superoxide (NOD.Ncf1m1J), we tested the hypothesis that loss of NOX-derived superoxide delays T1D by impairing autoreactive T infiltration of islets. Female NOD.Ncf1m1J mice (n=20) exhibit a significant delay in spontaneous T1D, as only 20% become diabetic by 40-weeks of age compared to 90% NOD mice (n=23). Immunophenotyping of 12-week-old NOD.Ncf1m1J mice revealed fewer pancreatic CCR2+CD4+ (1.9-fold) and CCR5+ CD4+ T cells (2.1-fold) compared to NOD. NOD.Ncf1m1J islets also had reduced total CD4+ (1.8-fold), CD25+ CD4+(2.0-fold), and effector CD4+ T cells (2.2-fold) compared to NOD. Using tetramer staining to detect autoreactive T cells, we observed a decrease in NOD.Ncf1m1J 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 data provides evidence that loss of NOX-derived superoxide can impair autoreactive T cell activation and islet-infiltration as a potential mechanism to delay T1D. Future studies will determine if NOX regulates islet chemokine synthesis to induce T cell migration. Supported by R01 DK126456 R01 DK127497 T32 GM109780 T32 AI007051 F31 DK130551