Salicylate is a transcriptional inhibitor of the inducible nitric oxide synthase in cultured cardiac fibroblasts.
We have previously reported that salicylate inhibits the inducible NO synthase (NOS 2) in cytokine-induced cardiac fibroblasts (Farivar, R. S., Chobanian, A. V., and Brecher, P. (1996) Circ. Res. 78, 759-768). To define further the mechanism of inhibition of NOS 2 by salicylate, we investigated NOS 2 mRNA induction by cytokines and determined the kinetics of inhibition by salicylate as compared to dexamethasone. Interferon-gamma plus tumor necrosis factor-alpha induced NOS 2 mRNA synergistically in a time- and dose-dependent manner. Both dexamethasone and salicylate equally inhibited the induction of NOS 2 mRNA in a time- and dose-dependent fashion, both before and after cytokine induction. Salicylate also inhibited interferon-gamma plus interleukin-1beta-induced NOS 2 mRNA. After 24 h of cytokine stimulation, salicylate stopped the induction of NOS 2 mRNA, whereas dexamethasone delayed the accumulation of transcript. In half-life experiments of NOS 2 mRNA, we found that dexamethasone reduced the half-life of NOS 2 mRNA from 7 to 4 h, whereas salicylate had no effect on mRNA stability. Tumor necrosis factor-alpha and interferon-gamma induced NF-kappaB (p50/p65) and STAT-1, respectively, as assessed by gel shift assays. Salicylate did not inhibit the cytokine induction of NF-kappaB or STAT-1. This study suggests that the anti-inflammatory mechanism of salicylate involves inhibition of NOS 2 transcription and shows that the effect is independent of NF-kappaB activation.
Farivar
R S
RS
Department of Pathology, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts 02118, USA. pbrecher@bu.edu
Brecher
P
P
D000818:Animals; D015152:Blotting, Northern; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D005347:Fibroblasts / Q000201:enzymology; D007371:Interferon-gamma / Q000494:pharmacology; D051379:Mice; D009206:Myocardium / Q000201:enzymology*; D016328:NF-kappa B / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D050794:STAT1 Transcription Factor; D012459:Salicylates / Q000494:pharmacology*; D020156:Salicylic Acid; D012980:Sodium Salicylate / Q000494:pharmacology; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D004268:DNA-Binding Proteins; D016328:NF-kappa B; D050794:STAT1 Transcription Factor; D012459:Salicylates; C494080:Stat1 protein, mouse; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase; D020156:Salicylic Acid; D012980:Sodium Salicylate