NADPH-derived superoxide influences CD4 T cell activation by oxidizing membrane thiols

Abstract

Abstract Reactive oxygen species play a key role in mediating T cell autoreactivity in the development of autoimmune diseases including Type 1 diabetes (T1D). It was recently shown that redox regulation of cell surface thiol levels can influence T cell activation, and the development of autoimmunity. Enhanced susceptibility in developing autoimmune arthritis has been attributed to an increase in the number of reduced cell surface thiols on arthritogenic CD4 T cells. We hypothesize that NAPDH (NOX)-derived superoxide can modulate the oxidation status of cell surface thiols on diabetogenic CD4 T cells, and thereby, influence T cell effector responses. We utilized the NOD.BDC-6.9.Ncf1m1J TCR transgenic mouse that possesses superoxide-deficient CD4 T cells that recognize the putative autoantigen, islet amyloid polypeptide. BDC-6.9.Ncf1m1J CD4 T cells stimulated with their cognate BDC-6.9 hybrid peptide displayed a 3.5- and 1.5-fold increase in IFN-γ and TNF-alpha production, respectively, in comparison to NOX-sufficient BDC-6.9 CD4 T cells. Hybrid peptide-stimulated BDC-6.9.Ncf1m1J CD4 T cells also displayed a 1.8-fold increase in the percentage of CD25 and a 1.5-fold increase in the percentage of CD69 in comparison to BDC-6.9 T cells. We examined the number of reduced cell surface thiols on CD4 T cells using Alexa Fluor 647 coupled with maleimide. Interestingly, hybrid peptide-stimulated BDC-6.9.Ncf1m1J CD4 T cells exhibited a 2.3-fold increase in the percentage of reduced cell surface thiols in comparison to stimulated BDC-6.9 CD4 T cells. Our data indicates that NOX-derived superoxide mediates the oxidation status of T cell surface thiols to influence diabetogenic CD4 T cell effector responses.