A novel mechanism for the inhibition of NF-kappaB activation in vascular endothelial cells by natural antioxidants.
The activation of Nuclear Factor kappa B (NF-kappaB) in vascular endothelial cells, in response to biochemical or biomechanical stimuli, is associated with vascular pathologies such as atherosclerosis. The present manuscript studies the ability of the natural antioxidant-pomegranate wine (PW), to inhibit tumor necrosis factor alpha (TNF-alpha) or shear stress-mediated-NF-kappaB activation in vascular endothelial cells and compares it to that of red wine (RW) and N-acetyl cysteine (NAC). PW and RW act as potent antioxidants in vascular endothelial cells, inhibiting the oxidation of 2',7'-dichloroflurescin diacetate in TNF-alpha treated cells. PW (as well as RW and NAC) acted as potent inhibitors of NF-kappaB activation (migration into the nucleus and DNA binding activity) in vascular endothelial cells. Nevertheless, PW and NAC failed to inhibit TNF-a induced serine 32/36 phosphorylation and IkappaBalpha degradation. Surprisingly, these antioxidants alone induced enhanced IkappaB serine phosphorylation, which was not accompanied by IkappaBalpha degradation, or NF-kappaB nuclear translocation. This phosphorylation did not involve serine 32/36. Furthermore, we show for the first time that NAC inhibited TNF-alpha mediated phosphorylation of p65 (ser536), whereas PW had no effect on this phosphorylation. Thus, natural antioxidants may serve as potent NF-kappaB inhibitors in vascular endothelial cells, yet act through unique and divergent pathways.
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D020672:I-kappa B Proteins / Q000378:metabolism; D029561:Lythraceae / Q000737:chemistry; D008954:Models, Biological; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D012694:Serine / Q000378:metabolism; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology; D014920:Wine
D000975:Antioxidants; D020672:I-kappa B Proteins; D016328:NF-kappa B; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D012694:Serine; D000111:Acetylcysteine