Cells of the immune system utilize multiple mechanisms to respond to environmental signals and recent studies
have demonstrated roles for two closely related proteins, the aryl hydrocarbon receptor (AHR) and hypoxia inducible
factor-1α (HIF1α), in these processes. The AHR is a transcription factor that is activated by diverse ligands found in the
diet and environmental pollution as well as by microbial and host-derived products. In contrast, HIF1α is a transcription
factor that is active under low oxygen conditions and mediates cellular responses to hypoxia. These evolutionarily
conserved proteins have roles in the interrelated processes of metabolism, tumorigenesis, and vascular development.
Additionally, the AHR and HIF1α have multiple effects on innate and adaptive immunity. This article provides an
overview of the biology of these transcription factors and reviews the effects of AHR and HIF1α signaling on immunity
to infection. There are many parallels between these two pathways and their functions highlight the importance of AHR
and HIF1α activity particularly at barrier surfaces in coordinating responses to pathogens.
Keywords: Adaptive immunity, aryl hydrocarbon receptor, hypoxia inducible factor-1á, infection, innate immunity,
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