ObjectiveTo investigate the effect of dexamethasone on polyinosinic:polycytidylic acid (PIC)-induced chemotactic factor expression in human bronchial epithelial (16hBE) cells and the underlying mechanism. Methods16hBE 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. ResultsPIC 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 (P<0.05,P<0.01). 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 (P<0.05, P<0.01). Dexamethasone pretreatment (1 μmol/L) significantly inhibited PIC-induced NF-κB p65 subunit expression (P<0.01). ConclusionGlucocorticoids can suppress PIC-induced IL-8 and IP-10 expression in human bronchial epithelial cells, probably through activation of NF-κB pathway.