Glutathione regulation of redox-sensitive signals in tumor necrosis factor-α-induced vascular endothelial dysfunction

• Published in: Toxicology and applied pharmacology 2007-06, Vol.221 (2), p.168-178
• Main Authors: Tsou, Tsui-Chun, Yeh, Szu Ching, Tsai, Feng-Yuan, Chen, Jein-Wen, Chiang, Huai-Chih
• Format: Article
• Language: English
• Subjects: Adhesion molecules; AP-1; Biological and medical sciences; Cells, Cultured; Endothelial cells; Endothelium, Vascular - cytology; Endothelium, Vascular - metabolism; Endothelium, Vascular - physiopathology; Glutathione - biosynthesis; Glutathione - physiology; GSH; Humans; Intercellular Adhesion Molecule-1 - genetics; Medical sciences; NF-κB; Oxidation-Reduction; Promoter Regions, Genetic; Protein Kinase Inhibitors - pharmacology; Protein Kinases - drug effects; TNF-α; Toxicology; Tumor Necrosis Factor-alpha - physiology
• ISSN: 0041-008X; 1096-0333
• DOI: 10.1016/j.taap.2007.03.005

We investigated the regulatory role of glutathione in tumor necrosis factor-alpha (TNF-α)-induced vascular endothelial dysfunction as evaluated by using vascular endothelial adhesion molecule expression and monocyte–endothelial monolayer binding. Since TNF-α induces various biological effects on vascular cells, TNF-α dosage could be a determinant factor directing vascular cells into different biological fates. Based on the adhesion molecule expression patterns responding to different TNF-α concentrations, we adopted the lower TNF-α (0.2 ng/ml) to rule out the possible involvement of other TNF-α-induced biological effects. Inhibition of glutathione synthesis by l-buthionine-( S, R)-sulfoximine (BSO) resulted in down-regulations of the TNF-α-induced adhesion molecule expression and monocyte–endothelial monolayer binding. BSO attenuated the TNF-α-induced nuclear factor-kappaB (NF-κB) activation, however, with no detectable effect on AP-1 and its related mitogen-activated protein kinases (MAPKs). Deletion of an AP-1 binding site in intercellular adhesion molecule-1 (ICAM-1) promoter totally abolished its constitutive promoter activity and its responsiveness to TNF-α. Inhibition of ERK, JNK, or NF-κB attenuates TNF-α-induced ICAM-1 promoter activation and monocyte–endothelial monolayer binding. Our study indicates that TNF-α induces adhesion molecule expression and monocyte–endothelial monolayer binding mainly via activation of NF-κB in a glutathione-sensitive manner. We also demonstrated that intracellular glutathione does not modulate the activation of MAPKs and/or their downstream AP-1 induced by lower TNF-α. Although AP-1 activation by the lower TNF-α was not detected in our systems, we could not rule out the possible involvement of transiently activated MAPKs/AP-1 in the regulation of TNF-α-induced adhesion molecule expression.