Department of Biomedical Engineering, Wayne State University, Detroit, 48202, MI, USA.
College of Engineering and Technology, American University of the Middle East, Kuwait.
Free Radic Biol Med. 2021 Mar;165:111-126. doi: 10.1016/j.freeradbiomed.2021.01.031. Epub 2021 Jan 23.
Low levels of ascorbate (Asc) are observed in cardiovascular and neurovascular diseases. Asc has therapeutic potential for the treatment of endothelial dysfunction, which is characterized by a reduction in nitric oxide (NO) bioavailability and increased oxidative stress in the vasculature. However, the potential mechanisms remain poorly understood for the Asc mitigation of endothelial dysfunction. In this study, we developed an endothelial cell based computational model integrating endothelial cell nitric oxide synthase (eNOS) biochemical pathway with downstream reactions and interactions of oxidative stress, tetrahydrobiopterin (BH) synthesis and biopterin ratio ([BH]/[TBP]), Asc and glutathione (GSH). We quantitatively analyzed three Asc mediated mechanisms that are reported to improve/maintain endothelial cell function. The mechanisms include the reduction of •BH to BH, direct scavenging of superoxide (O) and peroxynitrite (ONOO) and increasing eNOS activity. The model predicted that Asc at 0.1-100 μM concentrations improved endothelial cell NO production, total biopterin and biopterin ratio in a dose dependent manner and the extent of cellular oxidative stress. Asc increased BH availability and restored eNOS coupling under oxidative stress conditions. Asc at concentrations of 1-10 mM reduced O and ONOO levels and could act as an antioxidant. We predicted that glutathione peroxidase and peroxiredoxin in combination with GSH and Asc can restore eNOS coupling and NO production under oxidative stress conditions. Asc supplementation may be used as an effective therapeutic strategy when BH levels are depleted. This study provides detailed understanding of the mechanism responsible and the optimal cellular Asc levels for improvement in endothelial dysfunction.
在心血管和神经血管疾病中观察到抗坏血酸 (Asc) 水平降低。Asc 具有治疗内皮功能障碍的潜力，内皮功能障碍的特征是一氧化氮 (NO) 生物利用度降低和血管氧化应激增加。然而，对于 Asc 减轻内皮功能障碍的潜在机制仍知之甚少。在这项研究中，我们开发了一种基于内皮细胞的计算模型，该模型将内皮细胞一氧化氮合酶 (eNOS) 生化途径与下游反应以及氧化应激、四氢生物蝶呤 (BH) 合成和生物蝶呤比 ([BH]/[TBP])、Asc 和谷胱甘肽 (GSH) 的相互作用集成在一起。我们定量分析了三种据报道可改善/维持内皮细胞功能的 Asc 介导机制。这些机制包括将 •BH 还原为 BH、直接清除超氧化物 (O) 和过氧亚硝酸盐 (ONOO) 以及增加 eNOS 活性。该模型预测，在 0.1-100 μM 浓度范围内，Asc 以剂量依赖的方式改善内皮细胞 NO 产生、总生物蝶呤和生物蝶呤比以及细胞氧化应激的程度。Asc 增加了 BH 的可用性并在氧化应激条件下恢复了 eNOS 偶联。在 1-10 mM 浓度下，Asc 降低了 O 和 ONOO 水平，可以作为抗氧化剂。我们预测，谷胱甘肽过氧化物酶和过氧化物酶以及 GSH 和 Asc 的组合可以在氧化应激条件下恢复 eNOS 偶联和 NO 产生。当 BH 水平耗尽时，Asc 补充可能是一种有效的治疗策略。本研究提供了对负责机制的详细了解，以及改善内皮功能障碍的最佳细胞 Asc 水平。
