Objective: To investigate the effect of curcumin against cigarette smoke extract (CSE)- induced oxidative stress in human bronchial epithelial cells and explore the underlying mechanism.
Methods: Human 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-α (TNF-α), 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.
Results: The treatments did not cause significant changes in the cell viability. Exposure to CSE for 24 h significantly lowered PPARγ expression and increased TNF-α 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.
Conclusions: Curcumin 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.
目的: 探讨姜黄素对香烟烟雾提取物（CSE）诱导的人气道上皮16HBE细胞氧化应激和炎症反应的抑制作用及相关的分子机制。
方法: 使用shRNA-PPARγ（shPPARγ）转染人气道上皮16HBE细胞下调PPARγ表达。将16HBE细胞分为5组即对照组、姜黄素组、CSE组、CSE+姜黄素组和CSE+姜黄素+shRNA-PPARγ组。在0 h和24 h时使用MTT法对细胞活性进行检测；干预24 h后使用qPCR对细胞TNF-α、iNOS和PPARγ mRNA表达进行检测，采用western blot检测16HBE细胞中iNOS、PPARγ蛋白表达以及NF-κB p65磷酸化水平。
结果: 16HBE细胞在干预24 h后各组之间细胞活性未有明显统计学差异（P>0.05）。与对照组相比较，CSE干预24 h后PPARγ表达水平明显降低，TNF-α、iNOS表达及NF-κB p65磷酸化水平明显升高，差异均有统计学意义（P < 0.05）。但CSE组较CSE+姜黄素组和CSE+姜黄素+shPPARγ组PPARγ表达水平下降以及TNF-α、iNOS表达和NF-κB p65磷酸化水平升高更显著，差异均有统计学意义（P < 0.05）；且CSE+姜黄素+shPPARγ组较CSE+姜黄素组PPARγ表达水平下降以及TNF-α、iNOS表达和NF-κB p65磷酸化水平升高更明显，差异均有统计学意义（P < 0.05）。
结论: 姜黄素可以通过抑制PPARγ/ NF-κB信号通路减轻CSE诱导的人气道上皮16HBE细胞的炎症反应及氧化应激。为姜黄素应用于慢性阻塞性肺疾病等疾病的临床治疗奠定了理论基础。
Keywords: 16HBE cells; PPARγ; bronchial epithelial cells; cigarette smoke extract; nuclear factor-κB; oxidative stress.