Genetic regulation of nitric oxide-mediated metabolic reprogramming in dendritic cells

Abstract Dendritic cell (DC) activation is characterized by a rapid “metabolic switch” towards increased glycolysis that supports maturation. Sustained glycolysis post-activation is a requirement for survival in DC subsets that express inducible nitric oxide synthase (Nos2, iNOS), due to the production of nitric oxide (NO) which acts as an inhibitor of mitochondrial respiration. Long-term metabolic reprogramming in activated DCs has almost exclusively been studied in the strain C57BL/6J (B6), which experience loss of mitochondrial function due to NO accumulation. To assess the conservation of NO-driven metabolic regulation in DCs, we generated and compared DCs from B6 mice to the wild-derived genetically diverse PWD/PhJ (PWD) strain. We show attenuated iNOS induction, lowered NO production, and intact mitochondrial respiration in activated PWD DCs. To reduce genetic variability in our model, we generated DCs from a congenic mouse strain containing a genetic interval from PWD—including Nos2—on a B6 background. Activated DCs from the congenic strain produce NO at lower levels than B6, but NO production is not completely ablated as it is for pharmacologic or genetic interventions, thus this model allows for the subtle interrogation of NO-mediated metabolic reprogramming. We show that glucose-dependent carbon flux through the TCA cycle is altered in DCs with restrained NO production compared to B6 DCs, and we demonstrate that these differences are driven by NO. These studies provide a more comprehensive understanding of NO-mediated metabolic reprogramming in the murine myeloid lineage and establish a natural genetic model for investigating the contribution of NO in regulating the interplay between DC metabolism and immune function.