内毒素对体外培养大鼠肺微血管内皮细胞血管紧张素转换酶2表达的影响

Effect of endotoxin on expression of angiotensin converting enzyme-2 in cultured rat pulmonary microvascular endothelial cells

目的观察内毒素对大鼠肺微血管内皮细胞（RPMVEC）上血管紧张素转换酶2（ACE2）表达的影响，探讨ACE2参与内毒素性急性肺损伤（ALI）发生的机制。方法体外培养Wistar大鼠RPMVEC，以10mg／L的内毒素与之共同孵育；分别于实验3、6、12和24h用逆转录-聚合酶链反应（RT—PCR）和蛋白质免疫印迹法（Western blotting）检测ACE2的mRNA和蛋白表达。结果10mg／L内毒素处理RPMVEC后3h，ACE2的mRNA和蛋白表达即显著下降，6h有所回升，之后显著下降并持续至24h；统计学分析显示，除6h外，余各时间点ACE2 mRNA和蛋白表达均显著低于未用内毒素处理对照组（P〈0．05或P〈0．01）。结论10mg／L内毒素可下调RPMVEC中ACE2的mRNA和蛋白表达水平，可能是ALI发生机制之一。

Objective To observe the effects of endotoxin on angiotensin converting enzyme-2 （ACE2） expression in rat pulmonary microvascular endothelial cells （RPMVECs） in vitro, and discuss the rote of ACE2 in endotoxin-induced acute lung injury （ALI）. Methods In vitro, cultured RPMVECs were incubated with endotoxin （10 mg/L）, the expression of ACE2 mRNA and protein were detected by reverse transcriptase-polymerase chain reaction （RT-PCR） and Western blotting techniques at time points of 3, 6, 12, and 24 hours respectively after incubation with endotoxin. Results After the treatment of RPMVECs with endotoxin （10 mg/L）, the levels of ACE2 mRNA and protein decreased significantly, and then they increased slightly at 6 hours, followed by a continuous decrease until 24 hours. The statistic analysis demonstrated thai;, except at the 6-hour time point, the levels of ACE2 mRNA and protein expression at other time points were lower than those of control group significantly （P〈0.05 or P〈0.01）. Conclusion The downregulation of ACE2 mRNA and protein expression in RPMVECs by endotoxin may play an important role in pathogenesis of ALI.