摘要目的 观察COPD大鼠模型肺组织内质网应激的发生及肺泡上皮细胞凋亡.方法 24只Wistar雄性大鼠分为对照组和COPD模型组(简称模型组),每组12只.采用香烟烟雾暴露加气管内滴注脂多糖法建立COPD大鼠模型.造模完成后测定各组大鼠的肺功能,观察肺组织病理学变化,逆转录PCR法检测分子伴侣葡萄糖调节蛋白78(GRP78)、CCAAT/增强子结合蛋白同源蛋白(CHOP)mRNA水平,Western blot法检测GRP78、CHOP和活化的天冬氨酸特异性半胱氨酸蛋白酶-12(caspase-12)蛋白水平,原位缺口末端标记法检测大鼠肺泡上皮细胞凋亡.组间两两比较采用t检验.结果 模型组大鼠FEV0.3/FVC[(60±6)%]和动态肺顺应性[(0.17±0.02)cm H2O·ml-1·s-1,1 cm H2O=0.098 kPa]均明显低于对照组[(83±7)%和(0.31±0.03)cm H2O·ml-1·s-1],气道阻力[(0.64±0.07)ml/cm H2O]明显高于对照组[(0.32±0.03)ml/cm H2O],差异均有统计学意义(t值为-14.532～11.619,均P＜0.05);模型组大鼠支气管肺组织中GRP78和CHOP mRNA表达量的吸光度值(0.65±0.07和0.79±0.06)均明显高于对照组(0.21±0.04和0.07±0.04),差异均有统计学意义(t值分别为-19.102和-32.573,均P＜0.05);模型组大鼠肺组织中GRP78、CHOP和活化的caspase-12蛋白的吸光度值(0.83±0.06、0.82±0.06和0.81±0.07)均明显高于对照组(0.33±0.05、0.05±0.03和0.24±0.06),差异均有统计学意义(t值为-40.866～-22.070,均P＜0.05);模型组大鼠细胞凋亡指数[(32.4±3.7)%]明显高于对照组[(6.2±0.9)%],差异有统计学意义(t=-23.852,P＜0.05).结论 COPD大鼠模型的肺组织发生内质网应激,肺泡上皮细胞凋亡增加.内质网应激可能是介导肺泡上皮细胞凋亡的重要途径.

abstractsObjective To study the endoplasmic retieulum stress(ERS)and the apoptosis of alveolar epithelial cells in a COPD rat model.Methods Twenty-four Wister 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 pathoiogical 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. Results Significant decrease of FEV0.3/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).Conclusions 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.