OBJECTIVETo investigate the effect of curcumin against cigarette smoke extract (CSE)- induced oxidative stress in human bronchial epithelial cells and explore the underlying mechanism.

METHODSHuman bronchial epithelial cell line 16HBE was treated for 24 h with curcumin, CSE, CSE + curcumin, and CSE + curcumin with transfection by a short hairpin RNA targeting PPARγ (shPPARγ). MTT assay was used to observe the changes in the cell viability after the treatments. Quantitative real-time PCR was performed to detect the mRNA expressions of tumor necrosis factor- (TNF-), iNOS and PPARγ in the cells, and the protein expressions of iNOS, PPARγ and the phosphorylation of NF-κB p65 were detected using Western blotting.

RESULTSThe treatments did not cause significant changes in the cell viability. Exposure to CSE for 24 h significantly lowered PPARγ expression and increased TNF- and iNOS expressions and phosphorylation of NF-κB p65 in the cells. The effects of CSE were significantly suppressed by curcumin, but transfection of the cells with shRNA-PPARγ obviously abrogated the suppressive effects of curcumin.

CONCLUSIONSCurcumin suppresses CSE-induced oxidative stress and inflammation via the PPARγ/NF-κB signaling pathway in 16HBE cells, suggesting the potential of curcumin in the treatment of chronic obstructive pulmonary disease.