title: Downregulation of interleukin 8 gene expression in human fibroblasts: unique mechanism of transcriptional inhibition by interferon.
abstract: The chemotactic cytokine interleukin 8 (IL-8) is produced upon stimulation by various agents in many cell types, including connective-tissue fibroblasts. Tumor necrosis factor (TNF) and IL-1 are potent inducers of IL-8 expression. Earlier we showed that TNF-induced stimulation of IL-8 mRNA accumulation in human FS-4 fibroblasts was inhibited by interferon beta (IFN-beta) or IFN-gamma. Here we show that this inhibition is not specific for TNF, since IFN-beta also reduced IL-8 mRNA accumulation induced by IL-1 or the double-stranded RNA poly (I-C). Treatment with IFN-beta also decreased TNF-induced IL-8 protein accumulation. Interestingly, the inhibitory effect was much less pronounced when IFN-beta was added greater than or equal to 1 hr before TNF. The inhibitory action of IFN-beta on IL-8 mRNA accumulation was undiminished in the presence of inhibitors of protein synthesis. Nuclear run-on assays demonstrated that IFN-beta caused a marked inhibition of TNF-induced IL-8 gene transcription; the transcriptional activation of several other TNF-induced genes was not inhibited by IFN-beta. The results suggest that the specific inhibition of the transcriptional activation of IL-8 by IFN is due either to a transient inactivation of a factor required for IL-8 transcription or to the activation of a selective inhibitory factor.
authors.affiliation: Department of Microbiology, New York University Medical Center, New York 10016.
authors.forename: I C
authors.initials: IC
authors.lastname: Oliveira
authors.forename: P J
authors.initials: PJ
authors.lastname: Sciavolino
authors.forename: T H
authors.initials: TH
authors.lastname: Lee
authors.forename: J
authors.initials: J
authors.lastname: Vilcek
mesh_terms: D002460:Cell Line; D002467:Cell Nucleus / Q000502:physiology; D003513:Cycloheximide / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D016899:Interferon-beta / Q000494:pharmacology*; D007371:Interferon-gamma / Q000494:pharmacology*; D007375:Interleukin-1 / Q000494:pharmacology; D016209:Interleukin-8 / Q000235:genetics*; D007700:Kinetics; D011994:Recombinant Proteins / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D007375:Interleukin-1; D016209:Interleukin-8; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D016899:Interferon-beta; D007371:Interferon-gamma; D003513:Cycloheximide