Background: Hypoxic conditions area key feature of allergic rhinitis (AR), however, the role of hypoxia in AR remains to be fully understood. The aim of this study was to survey the effect of hypoxia on the Th17 response in AR patients by investigating the action of hypoxia-influenced signaling pathways on Th17 differentiation.
Methods: 23 AR patients and 15 healthy controls were recruited for this study. Under normoxia and hypoxic conditions, the expression of HIF-1α, AhR, CYP1A1 and CYP1B1 and the presence of Th17 cells in CD4+T cells were measured. Furthermore, the amount of ARNT combined with either HIF-1α or AhR was determined after the exposure of 2-(1H-Indol-3-ylcarbonyl)-4-thiazolecarboxylic acid methyl easter (ITE) with normoxia and hypoxia.
Results: HIF-1α and AhR expression were higher in CD4+T cells from AR patients than in those from healthy controls. In a hypoxic environment, the expression of HIF-1α was elevated in CD4+T cells of both AR patients and healthy controls. Meanwhile, the suppressive effects of a non-toxic AhR ligand (ITE) on the Th17 response and its positive effects on IL-10 production were suppressed in the cells of AR patients and healthy controls under hypoxia. These effects were arisen from HIF-1α out-competing AhR for ARNT binding which limited the activity of the AhR pathway.
Conclusions: The present results suggest that hypoxia is capable of promoting the Th17 response by reducing AhR activity via HIF-1α activity. Thus hypoxia may be intimately involved in the pathogenesis of AR.
Keywords: AhR; Allergic rhinitis; HIF-1α; Hypoxia.
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