N-Acetylcysteine Attenuates Cigarette Smoke-Induced Pulmonary Exacerbation in a Mouse Model of Emphysema

Objective: The purpose of this study was to investigate the effects of cigaret smoke (CS) on a mouse model of emphysema and examine the protective role of N-acetylcysteine (NAC) in the CS-induced exacerbation of pulmonary damage in the mice. Method: Particulate matter (PM) in sidestream cigaret smoke aerosol was analyzed by a scanning mobility particle sizer spectrometer. A mouse model of emphysema was established by an injection of porcine pancreatic elastase (PPE) into the trachea. Mice with emphysema were then exposed to filtered air, or sidestream CS with intragastric administration of NAC or normal saline. Mouse body weight, survival, pulmonary tissue histology, total antioxidant capacity (T-AOC) and malonaldehyde (MDA) contents in lung tissue, and inflammatory responses were examined. Results: Particles with a size of 346nm constituted 99.06% of CS PM. Mice exhibited ruptured alveolar septal, alveolar fusion, significantly increased mean lining interval, and reduced mean alveolar number (all p<0.05), 21d after PPE injection. Exposure of mice with emphysema to CS exacerbated the pulmonary tissue damage, caused weight loss, significantly increased mortality, decreased T-AOC, elevated MDA contents in lung tissue, and increased interleukin (IL)-1 levels in bronchoalveolar lavage (BAL) fluids (all p<0.05). Administration of NAC attenuated those CS-induced adverse effects in the mice and increased anti-inflammatory factor IL-10 levels in BAL fluids significantly (all p<0.05). Conclusions: Exposure of mice with emphysema to CS exacerbated the pulmonary damage, and NAC reduced the CS-mediated pulmonary damage by preventing oxidative damage and reducing inflammatory responses.