The YAP/HIF-1α/miR-182/EGR2 axis is implicated in asthma severity through the control of Th17 cell differentiation.

BACKGROUND

Asthma is a heterogeneous chronic inflammatory disease of the airway, involving reversible airflow limitation and airway remodeling. T helper 17 (Th17) cells play an important role in the pathogenesis of allergic asthma. However, there is limited understanding of the signaling pathways controlling Th17 cell differentiation in asthma. The aim of this study was to investigate if the Yes-associated protein (YAP)/hypoxia inducible factor-1α (HIF-1α)/microRNA-182 (miR-182)/early growth response 2 (EGR2) axis is involved in mediating Th17 cell differentiation and disease severity in asthma.

METHODS

The study included 29 pediatric patients with asthma, 22 healthy volunteers, ovalbumin-induced murine asthma models, and mouse naive CD4 T cells. The subpopulation of Th17 cells was examined by flow cytometry. The levels of interleukin-17A were determined by enzyme linked immunosorbent assay. Chromatin immunoprecipitation-quantitative polymerase chain reaction assays and dual-luciferase reporter gene assays were performed to examine interactions between HIF-1α and miR-182, and between miR-182 and EGR2.

RESULTS

YAP, HIF-1α, and miR-182 were upregulated but EGR2 was downregulated in human and mouse peripheral blood mononuclear cells from the asthma group. Abundant expression of YAP and HIF-1α promoted miR-182 expression and then inhibited EGR2, a target of miR-182, thus enhancing Th17 differentiation and deteriorating asthma and lipid metabolism dysfunction. In addition, in vivo overexpression of EGR2 countered the promoting effect of the YAP/HIF-1α/miR-182 axis on asthma and lipid metabolism dysfunction.

CONCLUSION

These results indicate that activation of the YAP/HIF-1α/miR-182/EGR2 axis may promote Th17 cell differentiation, exacerbate asthma development, and aggravate lipid metabolism dysfunction, thus suggesting a potential therapeutic target for asthma.