Boosting NAD preferentially blunts TH17 inflammation via arginine biosynthesis and redox regulatory control in control and psoriasis subjects [NR or placebo]
To evaluate whether NAD+-boosting modulates adaptive immunity, primary CD4+ T cells from healthy control and psoriasis subjects were exposed to vehicle or nicotinamide riboside (NR) supplementation. NR blunts IFNg and IL-17 secretion with greater effects on TH17 polarization. RNA-seq analysis implicates NR blunting of sequestosome 1 (SQSTM1/p62)-coupled oxidative stress. NR administration increases SQSTM1 and reduces reactive oxygen species (ROS) levels. Furthermore NR activates NRF2, and genetic knockdown of NRF2 and of the NRF2-dependent gene, SQSTM1 diminish NR amelioratory effects. Metabolomic analysis identify that NAD+-boosting increases arginine and fumarate biosynthesis and genetic knockdown of argininosuccinate lyase ameliorates NR-effects on IL-17 production. Hence, NR via amino acid metabolites orchestrate NRF2 activation, augments CD4+ T cell antioxidant defenses and attenuates TH17 responsiveness. Oral NR supplementation in healthy volunteers similarly increase serum arginine, SQSTM1 and antioxidant enzyme gene expression and blunts TH17 immune responsiveness, supporting evaluation of NAD+-boosting in CD4+ T cell linked inflammation. Overall design: CD4 T cells isolated were from human blood. RNA was extracted from CD4 T cells by miRNeasy Micro Kit (Qiagen). RNA was quantified using a Qubit 3.0 fluorometer (Thermo Fisher Scientific) and its integrity confirmed using an Agilent Technologies 2100 Bioanalyzer (Agilent).