title: Lack of glutathione peroxidase-1 facilitates a pro-inflammatory and activated vascular endothelium.
abstract: 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.
authors.affiliation: Baker IDI Heart and Diabetes Institute, Diabetic Complications Division, Melbourne, Victoria, Australia.
authors.forename: Arpeeta
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Baker IDI Heart and Diabetes Institute, Diabetic Complications Division, Melbourne, Victoria, Australia.
authors.forename: Derek
authors.initials: D
authors.lastname: Yuen
authors.affiliation: 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.
authors.forename: Olivier
authors.initials: O
authors.lastname: Huet
authors.affiliation: Baker IDI Heart and Diabetes Institute, Diabetic Complications Division, Melbourne, Victoria, Australia.
authors.forename: Raelene
authors.initials: R
authors.lastname: Pickering
authors.affiliation: Baker IDI Heart and Diabetes Institute, Diabetic Complications Division, Melbourne, Victoria, Australia.
authors.forename: Nada
authors.initials: N
authors.lastname: Stefanovic
authors.affiliation: Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Canada.
authors.forename: Pascal
authors.initials: P
authors.lastname: Bernatchez
authors.affiliation: Baker IDI Heart and Diabetes Institute, Diabetic Complications Division, Melbourne, Victoria, Australia. Electronic address: judy.dehaan@bakeridi.edu.au.
authors.forename: Judy B
authors.initials: JB
authors.lastname: de Haan
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000502:physiology; D004730:Endothelium, Vascular / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000172:deficiency*; D007249:Inflammation / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism; D000094765:Glutathione Peroxidase GPX1
chemical_list: D018836:Inflammation Mediators; D016328:NF-kappa B; D019010:Vascular Cell Adhesion Molecule-1; D005979:Glutathione Peroxidase; D000094765:Glutathione Peroxidase GPX1; C000722068:Gpx1 protein, mouse
keywords: Endothelial activation; Endothelial dysfunction; Glutathione peroxidase-1; Oxidative stress