RESUMEN
【Objective】 To investigate the effect of N-acetylcysteine （NAC） on mitochondrial damage of airway epithelial cells induced by cigarette smoke extract （CSE）. 【Methods】 Human airway epithelial cells （BEAS-2B） were cultured and divided into three groups as follows： normal control group， 7.5% （75 mL/L） CSE-treated group and 7.5% CSE plus NAC group. After stimulation for 24 hours， cell viability was determined by MTT， and the levels of mitochondrial reactive oxygen species （ROS） and mitochondrial membrane potential （MMP） were observed under the fluorescence microscope. MMP was also measured by flow cytometry， the protein expressions of Sirt3 and manganese superoxide dismutase （MnSOD） were detected by Western blotting， and MnSOD activity was measured by colorimetry. 【Results】 Pretreatment with NAC significantly improved the viability of airway epithelial cells （P<0.05）. The results of fluorescence microscopy and flow cytometry showed that NAC pretreatment significantly attenuated MMP decline in airway epithelial cells exposed to 7.5% CSE （P<0.05）. Compared with 7.5% CSE-treated group， mitochondrial ROS in airway epithelial cells was significantly decreased in 7.5% CSE plus NAC group （P<0.05）. In addition， pretreatment with NAC significantly inhibited the decrease of Sirt3 and MnSOD protein expression and improved MnSOD activity in airway epithelial cells exposed to 7.5% CSE （P<0.05）. 【Conclusion】 NAC attenuates CSE-induced airway epithelial mitochondrial damage through the regulation of Sirt3-MnSOD signaling pathway， which reveals a new mechanism of NAC treatment for chronic obstructive pulmonary disease.