Mitochondrial metabolism regulates the immunogenic responsiveness of dendritic cells [ATAC-seq]

Activation of dendritic cells (DCs) is linked to increased glycolysis. However, the role of the mitochondrial electron transport chain (ETC) in conventional DC subset function is poorly defined. Here, we revealed that immunogenic activation elevates late oxygen consumption in cDC1s, but not cDC2s. To investigate the relevance of the ETC in DC immunogenicity, we generated mice with impaired ETC complex III function in DCs. ETC complex III impairment attenuated poised or adjuvant-triggered cDC1 activation, migration and capability to prime T cells for anti-cancer immunity, while it had a mild effect on cDC2s. Mechanistically, loss of complex III in cDC1s led to a deregulated redox and metabolite balance causing DNA hypermethylation of PU.1-binding regions. This DNA hypermethylation diminished early stimulus-induced gene expression linked to immunogenic responsiveness of cDC1s, which was rescued via ectopic expression of alternative oxidase. Our findings show how the ETC differentially regulates the immunogenic function of cDC subsets.