Vitamin C inhibits NF-kappa B activation by TNF via the activation of p38 mitogen-activated protein kinase

J Immunol. 2000 Dec 15;165(12):7180-8. doi: 10.4049/jimmunol.165.12.7180.

Abstract

The transcription factor NF-kappaB is a central mediator of altered gene expression during inflammation, and is implicated in a number of pathologies, including cancer, atherosclerosis, and viral infection. We report in this study that vitamin C inhibits the activation of NF-kappaB by multiple stimuli, including IL-1 and TNF in the endothelial cell line ECV304 and in primary HUVECs. The induction of a NF-kappaB-dependent gene, IL-8, by TNF was also inhibited. The effect requires millimolar concentrations of vitamin C, which occur intracellularly in vivo, particularly during inflammation. Vitamin C was not toxic to cells, did not inhibit another inducible transcription factor, STAT1, and had no effect on the DNA binding of NF-kappaB. Inhibition by vitamin C was not simply an antioxidant effect, because redox-insensitive pathways to NF-kappaB were also blocked. Vitamin C was shown to block IL-1- and TNF-mediated degradation and phosphorylation of I-kappaBalpha (inhibitory protein that dissociates from NF-kappaB), due to inhibition of I-kappaB kinase (IKK) activation. Inhibition of TNF-driven IKK activation was mediated by p38 mitogen-activated protein kinase, because treatment of cells with vitamin C led to a rapid and sustained activation of p38, and the specific p38 inhibitor SB203580 reversed the inhibitory effect of vitamin C on IKK activity, I-kappaBalpha phosphorylation, and NF-kappaB activation. The results identify p38 as an intracellular target for high dose vitamin C.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / pharmacology
  • Ascorbic Acid / pharmacology*
  • Cell Line
  • DNA-Binding Proteins / antagonists & inhibitors
  • DNA-Binding Proteins / metabolism
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / metabolism
  • Enzyme Activation / drug effects
  • Enzyme Inhibitors / pharmacology
  • Humans
  • I-kappa B Kinase
  • I-kappa B Proteins*
  • Mitogen-Activated Protein Kinases / metabolism*
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / antagonists & inhibitors*
  • NF-kappa B / metabolism*
  • Phosphorylation / drug effects
  • Protein Serine-Threonine Kinases / antagonists & inhibitors
  • Protein Serine-Threonine Kinases / metabolism
  • Signal Transduction / drug effects
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors*
  • Tumor Necrosis Factor-alpha / physiology*
  • p38 Mitogen-Activated Protein Kinases

Substances

  • Antioxidants
  • DNA-Binding Proteins
  • Enzyme Inhibitors
  • I-kappa B Proteins
  • NF-kappa B
  • NFKBIA protein, human
  • Tumor Necrosis Factor-alpha
  • NF-KappaB Inhibitor alpha
  • Protein Serine-Threonine Kinases
  • CHUK protein, human
  • I-kappa B Kinase
  • IKBKB protein, human
  • IKBKE protein, human
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases
  • Ascorbic Acid