Angiotensin-converting enzyme 2 activation ameliorates pulmonary endothelial dysfunction in rats with pulmonary arterial hypertension through mediating phosphorylation of endothelial nitric oxide synthase
Angiotensin-converting enzyme 2 activation ameliorates pulmonary endothelial dysfunction in rats with pulmonary arterial hypertension through mediating phosphorylation of endothelial nitric oxide synthase
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血管紧张素转换酶 2 激活通过介导内皮一氧化氮合酶的磷酸化改善肺动脉高压大鼠的肺内皮功能障碍
DOI：
10.1016/j.jash.2017.10.009
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发表时间：
2017-12-01
影响因子：
--
通讯作者：
Liu, Yinglong
中科院分区：
文献类型：
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作者：
Li, Gang;Zhang, Han;Liu, Yinglong
本研究旨在观察血管紧张素转换酶2(ACE2)激活在预防大鼠肺动脉高压(PAH)过程中对肺内皮细胞功能的影响，并探讨其可能的机制。将大鼠随机分为5组：对照组、PAH组、PAH+间苯二酚(RES)组(ACE2激活)、PAH+RES+MLN4760组(ACE2抑制)、PAH+RES+L-NAME组(内皮型一氧化氮合酶(ENOS)抑制)。术后1周采用左全肺切除联合单次注射野百合碱的方法建立大鼠PAH模型，并给予相应的试剂。观察注射野百合碱3周后的血流动力学、血管内皮功能和病理改变。同时观察肺组织中一氧化氮(NO)浓度、eNOS的表达及其Ser1177和Thr495位eNOS的磷酸化。与PAH大鼠相比，Res诱导的ACE2激活导致平均肺动脉压(MPAP)降低和肺动脉重构(P<；0.05)。此外，PAH+RES组对乙酰胆碱(Ach)引起的mPAP降低有增强作用(P<；0.05)，但硝普钠(SNP)对此无明显影响(P>；0.05)。在ACE2激活的大鼠，Ach引起的mPAP下降与SNP引起的mPAP下降的比率(Ach/SNP)也增加(P<0.05)。然而，激活ACE2对PAH的保护作用可被ACE2拮抗剂MLN4760联合应用(均P>；0.05)所抵消。机制研究表明，PAH组肺组织中NO浓度下调，而PAH+RES组上调(P<；0.05)，而PAH+RES+MLN4760组与PAH组无明显差异(P>；0.05)。在调控NO释放的因素方面，我们发现PAH组eNOS表达上调，RES不影响eNOS的表达。与PAH组比较，注射Res后，eNOS Ser1177位的磷酸化水平增加，Thr495位的磷酸化水平降低(P<；0.05)。正如预期的那样，联合注射MLN4760消除了这些差异(P&gT；0.05)。PAH+RES+L-NAME组与PAH+RES组相比，Ach引起的mPAP降低明显减弱(P<；0.05)，而SNP组未见此作用(P>；0.05)。PAH+RES+L-NAME组平均动脉压下降的Ach/SNP比值也降低(P<；0.05)。ACE2的激活可能通过改善肺动脉内皮细胞的功能，对PAH的发生发展起到保护作用。这一作用可能是通过促进NO的释放来实现的，这是由于eNOS在Ser1177处的磷酸化增加和eNOS在Thr495处的去磷酸化所致。(C)2017美国高血压学会。版权所有。
This study aims to investigate the effect of angiotensin-converting enzyme 2 (ACE2) activation on pulmonary endothelial function in the process of preventing pulmonary arterial hypertension (PAH) in rat models and to explore the underlying mechanisms. Specific pathogen free rats were randomly divided into five groups including control group, PAH group, PAH + Resorcinolnaphthalein (Res) group (ACE2 activation), PAH + Res + MLN4760 group (ACE2 inhibition), and PAH + Res + L-NAME group (endothelial nitric oxide synthase [eNOS] inhibition). Rat PAH model was constructed using combined left pneumonectomy with a single dose of monocrotaline injection 1 week after the surgery, and the rats were then given corresponding reagents. Hemodynamics, endothelial function, and pathologic changes were evaluated 3 weeks after monocrotaline injection. The concentration of nitric oxide (NO), expression of eNOS, and phosphorylation of eNOS at Ser1177 and Thr495 in the lung tissues from rats were also investigated.The Res-induced activation of ACE2 led to decreased mean pulmonary arterial pressure (mPAP) and pulmonary artery remodeling in the PAH + Res group comparing with the PAH rats (P < .05). In addition, the reduction in mPAP induced by acetylcholine (Ach) was augmented in PAH + Res group (P < .05), but this was not observed under the treatment with sodium nitroprusside (SNP) (P > .05). The ratio of decrease in mPAP caused by Ach to that caused by SNP (Ach/SNP) was also increased (P < .05) in ACE2-activated rats. However, the protective effects of ACE2 activation on PAH were counteracted by co-administration of MLN4760, an ACE2 antagonist (all P > .05). The mechanistic study showed that the concentration of NO in the lung tissues was downregulated in the PAH group but upregulated in the PAH + Res group (P < .05), whereas the NO concentration in the PAH + Res + MLN4760 group was not obviously different from that in the PAH group (P > .05). Regarding the factors regulating NO release, we found that the eNOS was upregulated in the PAH group, and Res did not affect the expression of eNOS. The phosphorylation of eNOS at Ser1177 was increased but at Thr495 was reduced after Res injection, when compared with the PAH group (P < .05). As expected, co-injection of MLN4760 eliminated these differences (P > .05). The reduction in mPAP induced by Ach was attenuated in the PAH + Res + L-NAME group compared with the PAH + Res group (P < .05), but this was not observed in rats treated with SNP (P > .05). The Ach/SNP ratio of decline in mPAP was also decreased in the PAH + Res + L-NAME group (P < .05). Activation of ACE2 had a protective role in the development of PAH via improving the function of pulmonary arterial endothelium. This effect was potentially mediated by promoted NO release as a consequence of increased phosphorylation of eNOS at Ser1177 and dephosphorylation of eNOS at Thr495. (C) 2017 American Society of Hypertension. All rights reserved.