Combined effects of sodium fluoride and nano-TiO2 on human bronchial epithelial cells.

[Objective] To explore the combined effects of sodium fluoride(NaF)and nano-TiO2 on oxidative stress and apoptosis in human bronchial epithelial cells(16-HBE).[Methods] 16-HBE cells were exposed to NaF(mg/L,F-)and nano-TiO2(mg/L)with concentrations o(f0.0,0.0),(10.0,0.0),(20.0,0.0),(30.0,0.0),(0.0,10.0),(10.0,10.0),(20.0,10.0),(30.0,10.0),respectively.After 72 h exposure,the growth of 16-HBE was evaluated by the methyl thiazolyl tetrazolium(MTT)assay,totalsuperoxide dismutase(T-SOD)was measured by xanthine oxidase assay,malondialdehyde(MDA)was measured by thibabituric acid(TBA)assay,nitrogen monoxide(NO)was measured by nitrate reductase assay and apoptosis was observed by Hoechst 33258 staining method.[Results] Growth rates of 16-HBE in the groups exposed to 30.0 mg/L NaF(F-)and the combined exposure groups were lower than those of the control group(P 0.05).T-SOD of the group exposed to 30.0 mg/L NaF(F-)and 10.0 mg/L nano-TiO2 were lower than those of the control group(P 0.05).MDA of the combined exposure groups were higher than those of the control group(P 0.05).NO of all the treatment groups were higher than those of the control group(P 0.05).Coefficient effects on MDA and NO were observed in the combined exposure groups(P 0.05).Apoptosis rates of groups exposed to 20.0 and 30.0 mg/L NaF(F-) and all the combined exposure groups were higher than those of the control group.Fluoride was negatively correlated with T-SOD(P 0.01)and positively correlated with MDA,NO and apoptosis(P 0.05 or 0.01)of 16-HBE in the groups only exposed to NaF or the combined exposure groups.[Conclusion] Combined exposure of NaF and nano-TiO2 could enhance their oxidative stress damage to 16-HBE.Oxidative stress and apoptosis of 16-HBE were more serious with exposure to higher concentration of fluoride ion.