内质网应激在大鼠急性肺损伤中的意义

Significance of endoplasmic reticulum stress in a rat model of acute lung injury

目的探讨内质网应激在脂多糖内毒素诱导的大鼠急性肺损伤(ALI)中的意义。方法 Wistar大鼠40只,分为4组:30只大鼠用脂多糖内毒素制作急性肺损伤模型,分别于制模后1、6、12h三个时间点分批处死大鼠,命名为ALI1组、ALI2组、ALI3组,各10只;同时设对照组10只。对所有大鼠进行动脉血气分析,并采用逆转录聚合酶链反应法和免疫印迹法分别检测葡萄糖调节蛋白78(GRP78)、CCAAT增强子结合蛋白同源蛋白(CHOP)mRNA及其蛋白表达情况。采用流式细胞术定量分析肺组织细胞caspase-12的表达。结果与对照组比较,ALI各组大鼠的二氧化碳分压(PaCO2)、动脉血样分压(PaO2)及氧合指数均明显下降(P均<0.05),且ALI2组、ALI3组大鼠各指标较ALI1组下降更为明显(P均<0.05)。ALI各组大鼠GRP78的mRNA水平及caspase-12表达较对照组显著增加(P均<0.05),且ALI2组、ALI3组大鼠较ALI1组增加更为明显(P均<0.05)。而GRP78蛋白水平、CHOPmRNA及其蛋白表达水平仅在ALI2组、ALI3组与对照组比较时有统计学意义(P均<0.05)。结论内质网应激是内毒素源性的急性肺损伤的重要病理生理机制。

Objective To investigate the rat model of acute lung injury （ALI） induced by significance of endoplasmic reticulum stress in a lipopolysaccharide. Methods Forty Wistar rats were randomly divided into ALl 1 group, ALI 2 group, ALl 3 group and control group, 10 in each group. The rats in the ALI 1, ALI 2 and ALl 3 groups were sacrificed at 1, 6, 12 h respectively after lipopolysaccharides injection intravenously （10 mg/kg）. Meanwhile, the rats in the control group were injected with normal saline. Blood samples were collected from rats artery for blood gas analysis. The expression of glucoseregulated protein 78 （GRP78） and CCAAT/enhancer binding protein homologous protein （CHOP） at the mRNA levels were analyzed by reverse transcription polymerase chain reaction, protein expression levels of GRP78 and CHOP were determined by Western blotting. The expression of Caspase-12 was detected by the flow cytometry. Results The levels of partial pressure of CO2, partial pressure of oxygen and oxygenation index in the ALl 1, ALI 2 and ALI 3 groups were lower than those in the control group （all P 〈 0.05）, and these levels in the ALl 2 and ALI 3 groups were much lower than those in the ALl 1 group （all P〈 0.05）. The expression of GRP78 at the mRNA and Caspase- 12 in the ALl 1, ALI 2 and ALI 3 groups increased markedly as compared with that in the control group （all P 〈 0.05）, and the expression of GRP78 in the ALI 2 arid ALI 3 groups were