ACE/ACE2在AGT-REN双转基因高血压小鼠肾组织的表达变化及意义

目的: 观察血管紧张素原(AGT)-肾素(REN)双转基因高血压小鼠肾脏组织病理改变及血管紧张素转化酶(ACE)/血管紧张素转化酶2(ACE2)的表达变化,探讨ACE和ACE2在高血压肾损伤中的作用。方法: 实验分为4组,随机选择10月龄野生型、AGT转基因、REN转基因以及AGT-REN双转基因雄性C57小鼠各6只。每组动物颈动脉插管检测平均动脉压(MAP),1 h后处死小鼠;左侧肾脏置于10%中性甲醛固定,常规HE染色方法观察肾脏组织病理改变,免疫组化法观察肾脏ACE及ACE2的表达变化;右侧肾脏取出后放入蛋白裂解液中,提取蛋白,进行Western blotting实验,观察肾组织中ACE和ACE2蛋白表达。结果: 与野生型小鼠相比,AGT转基因小鼠MAP无明显变化(P>0.05),REN转基因小鼠MAP降低约15 mmHg(P<0.05);AGT-REN双转基因小鼠MAP明显升高约30 mmHg(P<0.05)。与野生型小鼠相比,AGT转基因和REN转基因小鼠肾组织未见明显病理改变,AGT-REN双转基因小鼠肾组织可见肾小动脉内膜及管壁显著增厚、管腔狭窄、纤维素样坏死、玻璃样变等典型恶性高血压肾损伤病理改变。免疫组化结果显示,与野生型小鼠相比,AGT转基因和REN转基因小鼠肾组织ACE和ACE2表达无明显差异(P>0.05),AGT-REN双转基因鼠肾组织ACE表达明显增高(P<0.05),而ACE2表达明显降低(P<0.05)。Western blotting结果显示:与野生型小鼠相比,AGT转基因鼠肾组织ACE和ACE2表达无明显变化;REN转基因鼠肾组织ACE表达无明显变化,ACE2表达稍降低(P<0.05);双转基因鼠肾组织ACE蛋白表达明显增强, ACE2蛋白表达水平显著降低,ACE/ACE2表达显著失衡。结论: AGT-REN双转基因可致小鼠恶性高血压,导致肾脏严重损伤;ACE/ACE2的表达失衡与血压改变密切相关,降低ACE或提高ACE2的表达可能对防治高血压具有重要意义。

Changes of ACE and ACE2 expression in kidney of AGT-REN double transgenic hypertensive mice

AIM: To investigate the role of imbalance between angiotensin-converting enzyme(ACE) and ACE2 in hypertensive renal damage by observing the changes of ACE and ACE2 expression in angiotensinogen(AGT)-renin(REN) double transgenic hypertensive mice carrying both human AGT and REN genes.METHODS: Twenty-four male mice of 4 genotypes including wild-type(WT) mice,AGT transgenic mice,REN transgenic mice and AGT-REN double transgenic mice were used in this study.All animals were 10 months old.The carotid artery was catheterized for observation of mean arterial pressure(MAP).After an hour,the mice were killed.The left kidney was prepared for the paraffin fixation,sectioning and HE staining to observe the pathological changes.ACE/ACE2 expression in the kidney was detected by the method of immunohistochemistry.The right kidney was used for Western blotting.RESULTS: No significant difference between AGT transgenic mice and WT mice in MAP was observed(P>0.05).MAP was approximately 15 mmHg lower in REN transgenic mice than that in WT mice(P<0.05).However,MAP was approximately 30 mmHg higher in AGT-REN double transgenic mice than that in WT mice(P<0.05).Compared with WT mice,AGT and REN transgenic mice did not show obvious pathological change,and AGT-REN double transgenic mice showed significant pathological changes,including thickened arteriolar wall,narrow lumen,fibrinoid necrosis and hyalinization.The results of both immunohistochemisty and Western blotting showed that the expression of renal ACE in AGT-REN double transgenic mice was markedly increased,and the expression of ACE2 was significantly decreased,suggesting that the expression of ACE and ACE2 was significantly imbalanced in AGT-REN double transgenic mice.CONCLUSION: Double transgenic mice carrying both human AGT and REN genes show malignant hypertension,renal damage,and imbalance of ACE and ACE2 expression.The imbalance of ACE and ACE2 in the kidney may play an important role in the pathogenesis of hypertension.