Sharma Arpeeta, Yuen Derek, Huet Olivier, Pickering Raelene, Stefanovic Nada, Bernatchez Pascal, de Haan Judy B
Baker IDI Heart and Diabetes Institute, Diabetic Complications Division, Melbourne, Victoria, Australia.
Baker IDI Heart and Diabetes Institute, Diabetic Complications Division, Melbourne, Victoria, Australia; Department of Anaesthesia and Intensive Care, CHRU La Cavale Blanche, Université de Bretagne Ouest, Brest, France.
Vascul Pharmacol. 2016 Apr;79:32-42. doi: 10.1016/j.vph.2015.11.001. Epub 2015 Nov 11.
A critical early event in the pathogenesis of atherosclerosis is vascular inflammation leading to endothelial dysfunction (ED). Reactive oxygen species and inflammation are inextricably linked and declining antioxidant defense is implicated in ED. We have previously shown that Glutathione peroxidase-1 (GPx1) is a crucial antioxidant enzyme in the protection against diabetes-associated atherosclerosis. In this study we aimed to investigate mechanisms by which lack of GPx1 affects pro-inflammatory mediators in primary aortic endothelial cells (PAECs) isolated from GPx1 knockout (GPx1 KO) mice. Herein, we demonstrate that lack of GPx1 prolonged TNF-α induced phosphorylation of P38, ERK and JNK, all of which was reversed upon treatment with the GPx1 mimetic, ebselen. In addition, Akt phosphorylation was reduced in GPx1 KO PAECs, which correlated with decreased nitric oxide (NO) bioavailability as compared to WT PAECs. Furthermore, IκB degradation was prolonged in GPx1 KO PAECS suggesting an augmentation of NF-κB activity. In addition, the expression of vascular cell adhesion molecule (VCAM-1) was significantly increased in GPx1 KO PAECs and aortas. Static and dynamic flow adhesion assays showed significantly increased adhesion of fluorescently labeled leukocytes to GPx1 KO PAECS and aortas respectively, which were significantly reduced by ebselen treatment. Our results suggest that GPx1 plays a critical role in regulating pro-inflammatory pathways, including MAPK and NF-κB, and down-stream mediators such as VCAM-1, in vascular endothelial cells. Lack of GPx1, via effects on p-AKT also affects signaling to eNOS-derived NO. We speculate based on these results that declining antioxidant defenses as seen in cardiovascular diseases, by failing to regulate these pro-inflammatory pathways, facilitates an inflammatory and activated endothelium leading to ED and atherogenesis.
动脉粥样硬化发病机制中的一个关键早期事件是导致内皮功能障碍（ED）的血管炎症。活性氧与炎症紧密相连，抗氧化防御能力下降与内皮功能障碍有关。我们之前已经表明，谷胱甘肽过氧化物酶-1（GPx1）是预防糖尿病相关动脉粥样硬化的关键抗氧化酶。在本研究中，我们旨在研究缺乏GPx1影响从GPx1基因敲除（GPx1 KO）小鼠分离的原代主动脉内皮细胞（PAECs）中促炎介质的机制。在此，我们证明缺乏GPx1会延长肿瘤坏死因子-α诱导的P38、ERK和JNK的磷酸化，而用GPx1模拟物依布硒啉处理后，所有这些都会逆转。此外，与野生型PAECs相比，GPx1 KO PAECs中Akt磷酸化降低，这与一氧化氮（NO）生物利用度降低相关。此外，GPx1 KO PAECS中IκB降解延长，表明NF-κB活性增强。此外，血管细胞粘附分子（VCAM-1）在GPx1 KO PAECs和主动脉中的表达显著增加。静态和动态流动粘附试验分别显示荧光标记的白细胞与GPx1 KO PAECs和主动脉的粘附显著增加，而依布硒啉处理可显著降低这种粘附。我们的结果表明，GPx1在调节血管内皮细胞中的促炎途径（包括MAPK和NF-κB）以及下游介质（如VCAM-1）方面起关键作用。缺乏GPx1通过对p-AKT的影响也会影响向eNOS衍生的NO的信号传导。基于这些结果，我们推测，在心血管疾病中看到的抗氧化防御能力下降，由于未能调节这些促炎途径，促进了炎症和活化的内皮，导致内皮功能障碍和动脉粥样硬化的发生。
