Nrf2 is a central regulator of the metabolic landscape in macrophages and finetunes their inflammatory response

Ryan, Dylan G.; Knatko, Elena V.; Casey, Alva; Hukelmann, Jens L.; Brenes, Alejandro J.; Naidu, Sharadha Dayalan; Higgins, Maureen; Tronci, Laura; Nikitopoulou, Efterpi; O’Neill, Luke A.J.; Frezza, Christian; Lamond, Angus I.; Abramov, Andrey Y.; Cantrell, Doreen A.; Murphy, Michael P.; Dinkova-Kostova, Albena T.

To overcome oxidative, inflammatory, and metabolic stress, cells have evolved networks of cytoprotective proteins controlled by nuclear factor erythroid 2 p45-related factor 2 (Nrf2) and its main negative regulator the Kelch-like ECH associated protein 1 (Keap1). Here, we used high-resolution mass-spectrometry to characterize the proteomes of macrophages with genetically altered Nrf2 status. Our analysis revealed significant differences among the genotypes in cellular metabolism and redox homeostasis, which we validated with respirometry and metabolomics, as well as in anti-viral immune pathways and the cell cycle. Nrf2 status significantly affected the proteome following lipopolysaccharide (LPS) stimulation, with alterations in redox, carbohydrate and lipid metabolism, and innate immunity observed. Of note, Nrf2 activation was found to promote mitochondrial fusion in inflammatory macrophages. The Keap1 inhibitor, 4-octyl itaconate (4-OI), a derivative of the mitochondrial immunometabolite itaconate, remodeled the inflammatory macrophage proteome, increasing redox and suppressing anti-viral immune effectors in a Nrf2-dependent manner. These data suggest that Nrf2 activation facilitates metabolic reprogramming and mitochondrial adaptation, and finetunes the innate immune response in macrophages. Graphical abstract Highlights First high-resolution proteome of macrophages with genetically altered Nrf2 status Nrf2 is key regulator of macrophage redox and intermediary metabolism Nrf2 finetunes the inflammatory response suppressing anti-viral immune and cytokine effectors, whilst promoting T cell activation factors Nrf2 regulates mitochondrial adaptation in inflammatory macrophages promoting the formation of a fused network 4-octyl itaconate (4-OI) suppresses anti-viral immune effectors in inflammatory macrophages in a Nrf2-dependent manner