Hypoxia-inducible factor 1 alpha limits dendritic cell stimulation of CD8 T cell immunity

Dendritic cells are sentinels of the immune system and represent a key cell in the activation of the adaptive immune response. Hypoxia-inducible factor 1 alpha (HIF-1 alpha)-a crucial oxygen sensor stabilized during hypoxic conditions-has been shown to have both activating and inhibitory effects in immune cells in a context- and cell-dependent manner. Previous studies have demonstrated that in some immune cell types, HIF-1 alpha serves a pro-inflammatory role. Genetic deletion of HIF-1 alpha in macrophages has been reported to reduce their pro-inflammatory function. In contrast, loss of HIF-1 alpha enhanced the pro-inflammatory activity of dendritic cells in a bacterial infection model. In this study, we aimed to further clarify the effects of HIF-1 alpha in dendritic cells. Constitutive expression of HIF-1 alpha resulted in diminished immunostimulatory capacity of dendritic cells in vivo, while conditional deletion of HIF-1 alpha in dendritic cells enhanced their ability to induce a cytotoxic T cell response. HIF-1 alpha-expressing dendritic cells demonstrated increased production of inhibitory mediators including IL-10, iNOS and VEGF, which correlated with their reduced capacity to drive effector CD8(+) T cell function. Altogether, these data reveal that HIF-1 alpha can promote the anti-inflammatory functions of dendritic cells and provides insight into dysfunctional immune responses in the context of HIF-1 alpha activation.