Hypoxia-inducible factor 1α plays a predominantly negative role in regulatory T cell functions.

Hypoxia-inducible factor 1α (HIF-1α) regulates cellular responses to hypoxia. However, conflicting roles for HIF-1α in the functions of regulatory T cells (Tregs) have been reported. In this review, we summarize observations on the requirement for HIF-1α for FOXP3 expression and Tregs development, as well as for HIF-1α-mediated downregulation of FOXP3 and Tregs destabilization. We also examine the association of HIF-1α with Tregs under pathogenic conditions. Based on these findings, we suggest that HIF-1α mainly plays a detrimental role in the function and stability of Tregs and that HIF-1α is disposable for the development and suppressive function of Tregs.