He Bai-mei, Luo Bai-ling, Peng Zhen-yu, Yuan Hao
Department of Respiratory Medicine, Xiangya Hospital of Central South University, Changsha 410008, China.
Zhonghua Jie He He Hu Xi Za Zhi. 2011 May;34(5):375-9.
To study the endoplasmic reticulum stress (ERS) and the apoptosis of alveolar epithelial cells in a COPD rat model.
Twenty-four Wistar rats were divided into a control group and a COPD group at random. The COPD rat model was established by intratracheal instillation of lipopolysaccharide (LPS) twice and exposure to cigarette smoke daily. The spirometry was conducted and the pathological changes were observed after the model was established. The levels of glucose regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP) mRNA were detected by reverse transcription-polymerase chain reaction (RT-PCR). The protein expression of GRP78, CHOP and caspase-12 was detected by Western blot. TdT-mediated dUTP nick end labeling (TUNEL) was used to analyze alveolar epithelial cell apoptosis. Comparisons between the two groups were performed by t-test.
Significant decrease of FEV(0.3)/FVC [(60 ± 6)%] and dynamic compliance of lung (CLdyn) [(0.17 ± 0.02) cm H2O×ml(-1)×s(-1)], and increase of airway resistance [(0.64 ± 0.07) ml/cm H2O] were found in the COPD group compared with the control group [(83 ± 7)%, (0.31 ± 0.03) cm H2O×ml(-1)×s(-1), (0.32 ± 0.03) ml/cm H2O] (t = -14.532 - 11.619, P < 0.05). GRP78 mRNA and CHOP mRNA densitometry [(0.65 ± 0.07), (0.79 ± 0.06)] were significantly increased in the COPD group compared with the control group [(0.21 ± 0.04), (0.07 ± 0.04), respectively] (t = -19.102 and -32.573, P < 0.05). GRP78, CHOP, and active caspase-12 protein densitometry (0.83 ± 0.06, 0.82 ± 0.06 and 0.81 ± 0.07) were significantly increased in the COPD group compared with the control group [(0.33 ± 0.05, 0.05 ± 0.03 and 0.24 ± 0.06), respectively] (t = -40.866 - -22.070, P < 0.05). More apoptotic alveolar epithelial cells were found in the COPD group [(32.4 ± 3.7)%] than in the control group [(6.2 ± 0.9)%] (t = -23.852, P < 0.05).
ERS was triggered in the lung tissues of COPD rats, especially in the alveolar epithelial cells. Alveolar epithelial cell apoptosis was increased in the COPD group. The ERS mediated apoptosis pathway may participate in the alveolar epithelial cell apoptosis in COPD.
研究慢性阻塞性肺疾病（COPD）大鼠模型中内质网应激（ERS）及肺泡上皮细胞凋亡情况。
将24只Wistar大鼠随机分为对照组和COPD组。通过气管内滴注脂多糖（LPS）两次并每日暴露于香烟烟雾建立COPD大鼠模型。模型建立后进行肺功能测定并观察病理变化。采用逆转录-聚合酶链反应（RT-PCR）检测葡萄糖调节蛋白78（GRP78）和CCAAT/增强子结合蛋白同源蛋白（CHOP）mRNA水平。采用蛋白质印迹法检测GRP78、CHOP和半胱天冬酶-12的蛋白表达。采用TdT介导的dUTP缺口末端标记法（TUNEL）分析肺泡上皮细胞凋亡情况。两组间比较采用t检验。
与对照组[（83±7）%，（0.31±0.03）cmH₂O×ml⁻¹×s⁻¹，（0.32±0.03）ml/cmH₂O]相比，COPD组第一秒用力呼气容积占用力肺活量的比值（FEV₀.₃/FVC）[（60±6）%]、肺动态顺应性（CLdyn）[（0.17±0.02）cmH₂O×ml⁻¹×s⁻¹]显著降低，气道阻力[（0.64±0.07）ml/cmH₂O]增加（t=-14.532～-11.619，P<0.05）。与对照组[分别为（0.21±0.04）、（0.07±0.04）]相比，COPD组GRP78 mRNA和CHOP mRNA光密度值[（0.65±0.07）、（0.79±0.06）]显著升高（t=-19.102和-32.573，P<0.05）。与对照组[分别为（0.33±0.05）、（0.05±0.03）和（0.24±0.06）]相比，COPD组GRP78、CHOP和活化的半胱天冬酶-12蛋白光密度值（0.83±0.06、0.82±0.06和0.81±0.07）显著升高（t=-40.866～-22.070，P<0.05）。与对照组[（6.2±0.9）%]相比，COPD组凋亡的肺泡上皮细胞更多[（32.4±3.7）%]（t=-23.852，P<0.05）。
COPD大鼠肺组织中触发了ERS，尤其是在肺泡上皮细胞中。COPD组肺泡上皮细胞凋亡增加。ERS介导的凋亡途径可能参与了COPD中肺泡上皮细胞的凋亡。
