Centre for Chronic Disease, College of Health and Biomedicine, Victoria University, Melbourne, Vic., Australia.
Department of Pharmacy, University of Patras, Patras, Greece.
Cardiovasc Ther. 2017 Dec;35(6). doi: 10.1111/1755-5922.12306. Epub 2017 Oct 4.
Hyperhomocysteinemia (HHcy) impairs nitric oxide endothelium-dependent vasodilation, consequently leading to atherosclerosis, a risk factor for cardiovascular disease. Novel treatments for HHcy are necessary.
We tested the hypothesis that alamandine, a vasoactive peptide of the renin-angiotensin system (RAS), could reverse HHcy-induced vascular dysfunction through the MrgD receptor and that this is mediated by the protein kinase A (PKA) pathway. Furthermore, we sought to determine a putative binding model of alamandine to the MrgD receptor through docking and molecular dynamics simulations.
The abdominal aorta was excised from New Zealand white rabbits (n = 15) and incubated with 3 mmol/L Hcy (to mimic HHcy) to induce vascular dysfunction in vitro. Vascular function was assessed by vasodilatory responses to cumulative doses of acetylcholine.
Vasodilation was significantly impaired in HHcy-incubated aortic rings while alamandine reversed this effect (control, 74.2 ± 5.0%; Hcy, 30.3 ± 9.8%; alamandine + Hcy, 59.7 ± 4.8%, P < .0001). KT5720 (PKA inhibitor) significantly inhibited the ability of alamandine to attenuate the impaired vasodilation caused by HHcy (KT5720 + Hcy + alamandine, 27.1 ± 24.1, P < .01). Following immunohistochemistry analysis, the MrgD receptor was highly expressed within the media and endothelial layer of aortic rings in HHcy compared to control (media: 0.23 ± 0.003 vs control 0.16 ± 0.01, P < .05 and endothelium: 0.68 ± 0.07 vs control 0.13 ± 0.02, P < .01, in PA/I (A.U) units). Computational studies also propose certain interactions of alamandine within the MrgD transmembrane domain.
This study shows that alamandine is effective in reversing HHcy-induced vascular dysfunction, possibly through the PKA signaling pathway via MrgD. Our results indicate a therapeutic potential of alamandine in reversing the detrimental effects of HHcy.
高同型半胱氨酸血症（HHcy）损害一氧化氮内皮依赖性血管舒张，进而导致动脉粥样硬化，这是心血管疾病的一个风险因素。HHcy 需要新的治疗方法。
我们验证了这样一个假设，即 alamandine，一种肾素-血管紧张素系统（RAS）的血管活性肽，可以通过 MrgD 受体逆转 HHcy 引起的血管功能障碍，并且这种作用是通过蛋白激酶 A（PKA）途径介导的。此外，我们试图通过对接和分子动力学模拟确定 alamandine 与 MrgD 受体的潜在结合模型。
从新西兰白兔（n=15）中取出腹主动脉，并用 3mmol/L Hcy（模拟 HHcy）孵育以在体外诱导血管功能障碍。通过累积剂量乙酰胆碱评估血管舒张反应来评估血管功能。
HHcy 孵育的主动脉环的血管舒张明显受损，而 alamandine 逆转了这种作用（对照组，74.2±5.0%；HHcy 组，30.3±9.8%；alamandine+Hcy 组，59.7±4.8%，P<.0001）。KT5720（PKA 抑制剂）显著抑制 alamandine 减弱 HHcy 引起的血管舒张受损的能力（KT5720+Hcy+alamandine 组，27.1±24.1，P<.01）。免疫组织化学分析后，与对照组相比，HHcy 时 MrgD 受体在主动脉环的中膜和内皮层高度表达（中膜：0.23±0.003 与对照组 0.16±0.01，P<.05 和内皮：0.68±0.07 与对照组 0.13±0.02，P<.01，在 PA/I（A.U）单位）。计算研究还提出了 alamandine 在 MrgD 跨膜结构域内的某些相互作用。
这项研究表明，alamandine 可有效逆转 HHcy 引起的血管功能障碍，可能通过 MrgD 介导的 PKA 信号通路。我们的结果表明 alamandine 具有逆转 HHcy 有害影响的治疗潜力。
