Hyperhomocysteinemia activates nuclear factor-kappaB in endothelial cells via oxidative stress

• Published in: Circulation research 2004-01, Vol.94 (1), p.28-36
• Main Authors: Au-Yeung, Kathy K W, Woo, Connie W H, Sung, Fion L, Yip, Johnny C W, Siow, Yaw L, O, Karmin
• Format: Article
• Language: English
• Subjects: Animals; Aorta - chemistry; Aorta - cytology; Cells, Cultured; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Homocysteine - pharmacology; Hyperhomocysteinemia - metabolism; I-kappa B Kinase; I-kappa B Proteins - metabolism; Male; NF-kappa B - metabolism; NF-KappaB Inhibitor alpha; Oxidative Stress; Protein-Serine-Threonine Kinases - metabolism; Rats; Rats, Sprague-Dawley; Superoxides - analysis; Superoxides - metabolism
• ISSN: 0009-7330; 1524-4571

Hyperhomocysteinemia is an independent risk factor for cardiovascular diseases. Our previous studies demonstrated an important interaction between nuclear factor-kappaB (NF-kappaB) activation and homocysteine (Hcy)-induced chemokine expression in vascular smooth muscle cells and macrophages. The objective of the present study was to investigate the in vivo effect of hyperhomocysteinemia on NF-kappaB activation and the underlying mechanism of Hcy-induced NF-kappaB activation in endothelial cells. Hyperhomocysteinemia was induced in Sprague-Dawley rats after 4 weeks of a high-methionine diet. The activated form of NF-kappaB and increased level of superoxide anions were detected in the endothelium of aortas isolated from hyperhomocysteinemic rats. The underlying mechanism of Hcy-induced NF-kappaB activation was investigated in human umbilical cord vein endothelial cells and in human aortic endothelial cells. Incubation of cells with Hcy (100 micromol/L) activated IkappaB kinases (IKKalpha and IKKbeta), leading to phosphorylation and subsequent degradation of IkappaBalpha. As a consequence, NF-kappaB nuclear translocation, enhanced NF-kappaB/DNA binding activity, and increased transcriptional activity occurred. Additional analysis revealed a marked elevation of superoxide anion levels in Hcy-treated cells. Treatment of cells with a superoxide anion scavenger (polyethylene glycol-superoxide dismutase) or IkappaB kinase inhibitor (prostaglandin A(1)) could prevent Hcy-induced activation of IKK kinases and NF-kappaB in endothelial cells. In conclusion, these results suggest that Hcy-induced superoxide anion production may play a potential role for NF-kappaB activation in the early stages of atherosclerosis in the vascular wall via activation of IkappaB kinases.