Intermittent Hypoxia Aggravates TNF-α-induced Inflammation In Human Bronchial Epithelial Cells By Regulating The NF-κB/HIF-1α Signaling Pathway

Background: Obstructive sleep apnea hypopnea syndrome(OSAHS)and asthma are common chronic diseases of the respiratory system.Because OSAHS and asthma have many common risk factors,they often occur simultaneously and interact with each other.Studies have shown that OSAHS is an independent risk factor for severe asthma,which can aggravate airway inflammation of asthma and is associated with inflammation mainly caused by the increase of neutrophils.But the mechanism of this is still unclear.Hypoxia inducible factor 1α(HIF-1α)is a key factor in the body’s response to hypoxia stress,and intermittent hypoxia can promote multiple target organ damage by upregulating HIF-1α expression.However,the role and mechanism of HIF-1α in airway inflammation aggravated by intermittent hypoxia in asthma have not been studied.Objective: To explore whether intermittent hypoxia can aggravate airway inflammation in asthma by upregulating HIF-1α expression,and to elucidate its potential mechanism.Methods: 1)After stimulating human airway epithelial cells(BEAS-2B)with tumor necrosis factor(TNF-α)and simultaneously exposed to normoxia or intermittent hypoxia,the expression of inflammatory cytokines IL-6 and IL-8 was detected by enzyme linked immunosorbent assay(ELISA).2)After TNF-α-induced BEAS-2B cells were treated with intermittent hypoxia,the expression of HIF-1α,nuclear factor-κB(NF-κB P65)and phosphorylated nuclear factor-κB(p-P65)were detected by Western blot.3)After BEAS-2B cells were transfected with HIF-1α small interfering RNA(siRNA),the expression of HIF-1α,NF-κB P65,p-P65,and inflammatory cytokines IL-6 as well as IL-8 were detected.4)After BEAS-2B cells were pretreated with NF-κB specific inhibitor(Bay 11-7082),the expression of HIF-1α,NF-κB P65,p-P65,IL-6 as well as IL-8 were detected.Results: 1)Interval hypoxia promoted the secretion of inflammatory cytokines IL-6and IL-8 in TNF-α-induced BEAS-2B cells.2)Interval hypoxia significantly up-regulated NF-κB P65 phosphorylation and HIF-1α expression in TNF-α-induced BEAS-2B cells.3)After BEAS-2B cells were transfected with HIF-1α siRNA,the expression of HIF-1α,IL-6 as well as IL-8 were distinctly decreased.However,there was no significant change in the expression of p-P65.4)After BEAS-2B cells were pretreated with Bay 11-7082,the expression of IL-6,IL-8 as well as HIF-1α was remarkably decreased.Conclusion: Interval hypoxia can promote the secretion of inflammatory cytokines IL-6 and IL-8 in TNF-α-induced BEAS-2B cells by up-regulating the expression of HIF-1α,which is dependent on the phosphorylation of NF-κB P65.