Sirtuin 3 Inhibits Airway Epithelial Mitochondrial Oxidative Stress in Cigarette Smoke-Induced COPD

Mitochondrial damage in airway epithelial cells plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Sirtuin 3 (Sirt3) is a mitochondrial deacetylase regulating mitochondrial function, but its role in the pathogenesis of COPD is still unknown. The aim of the present study was to investigate the effect of Sirt3 on airway epithelial mitochondria in cigarette smoke-induced COPD. Our present study has shown serious airway inflammation, alveolar space enlargement, and mitochondrial damage of the airway epithelium in COPD rats. Compared to the control rats, Sirt3 protein expression was significantly decreased in the airway epithelium and lung tissue homogenate from COPD rats. In airway epithelial cells (BEAS-2B), cigarette smoke extract (CSE) treatment significantly decreased mRNA and protein expression of Sirt3 and manganese superoxide dismutase (MnSOD), as well as MnSOD activity in a concentration and time-dependent manner. Sirt3 siRNA further significantly intensified the decreases in MnSOD expression and activity and aggravated mitochondrial oxidative stress and cell injury when airway epithelial cells were treated with 7.5% CSE. In contrast, Sirt3 overexpression significantly prevented the decrease of MnSOD expression and activity and improved mitochondrial oxidative stress and cell injury in CSE-treated airway epithelial cells. These data suggest that Sirt3 inhibits airway epithelial mitochondrial oxidative stress possibly through the regulation of MnSOD, thereby contributing to the pathogenesis of COPD.