Senescence marker protein-30 protects mice lungs from oxidative stress, aging, and smoking

Rationale: Senescence marker protein-30 (SMP30) is a multifunctional protein providing protection to cellular functions from age-associated deterioration. We previously reported that SMP30 knockout (SMP30Y/-) mice are capable of being novel models for senile lung with age-related airspace enlargement and enhanced susceptibility to harmful stimuli. Objectives: Aging and smoking are considered as major contributing factors for the development of pulmonary emphysema. We evaluated whether SMP30Y/- mice are susceptible to oxidative stress associated with aging and smoking. Methods: Age-related changes of protein carbonyls in lung tissues from the wild-type (SMP30Y/+) and SMP30Y/- mice were evaluated. Both strains were exposed to cigarette smoke for 8 wk. Histopathologic and morphologic evaluations of the lungs, protein carbonyls and malondialdehyde in the lung tissues, total glutathione content in the bronchoalveolar lavage fluid, and degree of apoptosis of lung cells were determined. Measurements and Main Results: In the lungs of SMP30Y/- mice, protein carbonyls tended to increase with aging and were significantly higher than the age-matched SMP30Y/+ mice. Cigarette smoke exposure generated marked airspace enlargement (23.3% increase of the mean linear intercepts) with significant parenchymal destruction in the SMP30Y/- mice but not in the SMP30Y/+ mice (5.4%). The protein carbonyls, malondialdehyde, total glutathione, and apoptosis of lung cells were significantly increased after 8-wk exposure to cigarette smoke in the SMP30Y/- mice. Conclusions: Our results suggest that SMP30 protects mice lungs from oxidative stress associated with aging and smoking. The SMP30Y/- mice could be useful animal models for investigating age-related lung diseases, including cigarette smoke-induced pulmonary emphysema.