Maiocchi Sophie, Ku Jacqueline, Hawtrey Tom, De Silvestro Irene, Malle Ernst, Rees Martin, Thomas Shane R, Morris Jonathan C
School of Medical Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia.
Center for Nanotechnology in Drug Delivery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
Chem Res Toxicol. 2021 Jun 21;34(6):1681-1692. doi: 10.1021/acs.chemrestox.1c00094. Epub 2021 Jun 4.
The heme enzyme myeloperoxidase (MPO) is a key mediator of endothelial dysfunction and a therapeutic target in cardiovascular disease. During inflammation, MPO released by circulating leukocytes is internalized by endothelial cells and transcytosed into the subendothelial extracellular matrix of diseased vessels. At this site, MPO mediates endothelial dysfunction by catalytically consuming nitric oxide (NO) and producing reactive oxidants, hypochlorous acid (HOCl) and the nitrogen dioxide radical (NO). Accordingly, there is interest in developing MPO inhibitors that effectively target endothelial-localized MPO. Here we studied a series of piperidine nitroxides conjugated to polyamine moieties as novel endothelial-targeted MPO inhibitors. Electron paramagnetic resonance analysis of cell lysates showed that polyamine conjugated nitroxides were efficiently internalized into endothelial cells in a heparan sulfate dependent manner. Nitroxides effectively inhibited the consumption of MPO's substrate hydrogen peroxide (HO) and formation of HOCl catalyzed by endothelial-localized MPO, with their efficacy dependent on both nitroxide and conjugated-polyamine structure. Nitroxides also differentially inhibited protein nitration catalyzed by both purified and endothelial-localized MPO, which was dependent on NO scavenging rather than MPO inhibition. Finally, nitroxides uniformly inhibited the catalytic consumption of NO by MPO in human plasma. These studies show for the first time that nitroxides effectively inhibit local oxidative reactions catalyzed by endothelial-localized MPO. Novel polyamine-conjugated nitroxides, ethylenediamine-TEMPO and putrescine-TEMPO, emerged as efficacious nitroxides uniquely exhibiting high endothelial cell uptake and efficient inhibition of MPO-catalyzed HOCl production, protein nitration, and NO oxidation. Polyamine-conjugated nitroxides represent a versatile class of antioxidant drugs capable of targeting endothelial-localized MPO during vascular inflammation.
血红素酶髓过氧化物酶（MPO）是内皮功能障碍的关键介质，也是心血管疾病的治疗靶点。在炎症过程中，循环白细胞释放的MPO被内皮细胞内化，并通过转胞吞作用进入病变血管的内皮下细胞外基质。在这个部位，MPO通过催化消耗一氧化氮（NO）并产生活性氧化剂、次氯酸（HOCl）和二氧化氮自由基（NO₂）来介导内皮功能障碍。因此，人们对开发能有效靶向内皮定位MPO的MPO抑制剂很感兴趣。在这里，我们研究了一系列与多胺部分共轭的哌啶氮氧化物，作为新型的内皮靶向MPO抑制剂。细胞裂解物的电子顺磁共振分析表明，多胺共轭氮氧化物以硫酸乙酰肝素依赖的方式有效地内化到内皮细胞中。氮氧化物有效地抑制了内皮定位的MPO催化的MPO底物过氧化氢（H₂O₂）的消耗和HOCl的形成，其功效取决于氮氧化物和共轭多胺的结构。氮氧化物还不同程度地抑制了纯化的和内皮定位的MPO催化的蛋白质硝化作用，这取决于NO清除而不是MPO抑制。最后，氮氧化物均匀地抑制了人血浆中MPO对NO的催化消耗。这些研究首次表明，氮氧化物有效地抑制了内皮定位的MPO催化的局部氧化反应。新型多胺共轭氮氧化物乙二胺-TEMPO和腐胺-TEMPO，成为有效的氮氧化物，独特地表现出高内皮细胞摄取和对MPO催化的HOCl产生、蛋白质硝化和NO氧化的有效抑制。多胺共轭氮氧化物代表了一类通用的抗氧化药物，能够在血管炎症期间靶向内皮定位的MPO。
