Inhibitory effects of dexamethasone against polyinosinic:polycytidylic acid-induced chemotactic factor expression in bronchial epithelial cells and the underlying mechanism

Abstract

Objective To investigate the effect of dexamethasone on polyinosinic: polycytidylic acid(PIC)-induced chemotactic factor expression in human bronchial epithelial(16hBE) cells and the underlying mechanism.Methods 16hBE cells were treated with different concentrations of PIC(0.001,0.01,0.1,and 1 μg/ml) and dexamethasone(0.1,1,and 10 μmol/L).IL 8 and IP-10 mRNA levels were detected by RT-PCR 6 h after stimulation.IL-8 and IP-10 protein levels in the culture supernatant were detected by ELISA 24 h after stimulation.NF-κB p65 subunit expression was detected by immunohistochemical staining.Results PIC concentration-dependently(0.001,0.01,and 0.1 μg/ml) increased the expression of IL-8 and IP-10 mRNA and protein compared with the control group,with significant differences found when PIC at 0.01 μg/ml and 0.1 μg/ml(P0.05,P0.01).When the concentration of PIC was 1 μg/ml,the expressions of IL-8 and IP-10 were decreased at both mRNA and protein levels.Pretreatment with dexamethasone(1 μmol/L and 10 μmol/L) for 0.5 h significantly inhibited the IL-8 and IP-10 expression at both mRNA and protein levels(P0.05,P0.01).Dexamethasone pretreatment(1 μmol/L) significantly inhibited PIC-induced NF-κB p65 subunit expression(P0.01).Conclusion Glucocorticoids can suppress PIC-induced IL-8 and IP-10 expression in human bronchial epithelial cells,probably through activation of NF-κB pathway.