Effect of the proteasome inhibitor MG-132 on pulmonary epithelial cell apoptosis in rats with hyperoxiainduced lung injury

Objective To observe the effect of the proteasome inhibitor MG-132 on pulmonary epithelial cell apoptosis in rats with hyperoxia-induced lung injury and to investigate the underlying mechanism. Methods Completely randomized design was adopted for this study. Twenty-six SD rats were randomly divided into 4 groups :hyperoxia group (n=8), hyperoxia plus MG-132 group (n=8), MG-132 group (n=5) ,control group (n =5). Based on the hyperoxia-induced lung injury rat model,the following parameters were determined: histopathological changes of lung tissue, cell apoptosis index via TUNEL method, Bax and Bcl-2 expression via immunohistochemistry. Additionally, Bcl-2/Bax ratio was calculated. Results After hyperoxia exposure,serious acute inflammatory reaction was found in hyperoxia group. The apoptosis index of hyperoxia group and hyperoxia plus MG-132 group (66.76±7.64,34.78±4.40 ) were significantly higher than those of control group and MG-132 group (14.48±1.75,12.88±1.95), and furthermore, hyperoxia plus MG132 group had lower apoptosis index than hyperoxia group (1.22±0.15 vs. 0.87±0.11, P<0.05). Hyperoxia plus MG-132 group had higher Bcl-2/Bax ratio than hyperoxia group (P<0.05). Conclusion Hyperoxia can induce pulmonary epithelial cell apoptosis. Proteasome inhibitor MG-132 can alleviate hyperoxia-induced lung injury through regulating Bax and Bcl-2 expression. Key words: Proteasome inhibitor; MG-132; Hyperoxia; Apoptosis; Bax; Bcl-2