title: Differential regulation of eotaxin expression by IFN-gamma in airway epithelial cells.
abstract: BACKGROUND
  Eotaxin is a chemokine that binds with high affinity and specificity to the chemokine receptor CCR3 and plays an important role in the pathogenesis of allergic disease.
  
  
  OBJECTIVE
  We studied the regulation of eotaxin expression by the T(H)1 cytokine IFN-gamma and analyzed its molecular mechanisms.
  
  
  METHODS
  Levels of eotaxin mRNA and protein expression in the airway epithelial cell line BEAS-2B were determined with RT-PCR and ELISA. Mechanisms of transcriptional regulation were assessed by means of electrophoretic mobility shift assays and luciferase assay with eotaxin promoter-luciferase reporter plasmids.
  
  
  RESULTS
  Although IFN-gamma did not directly induce the expression of eotaxin protein, it increased the induction by TNF-alpha when these cytokines were added simultaneously. In contrast, preincubation of cells with IFN-gamma for 24 hours profoundly inhibited the production induced by TNF-alpha. IFN-gamma did not influence the TNF-alpha-induced binding of nuclear factor kappaB to a DNA probe derived from the eotaxin promoter. IFN-gamma did not increase the ability of TNF-alpha to activate the eotaxin promoter. Studies of eotaxin mRNA levels indicate that IFN-gamma combined with TNF-alpha increased the expression of eotaxin mRNA. When cells were preincubated with IFN-gamma, there was no inhibition of the appearance of eotaxin mRNA.
  
  
  CONCLUSIONS
  These studies demonstrate that IFN-gamma enhances eotaxin expression when added in combination with TNF-alpha and profoundly inhibits eotaxin expression after preincubation. In both cases the available data indicate that the effect is mediated by a posttranscriptional mechanism.
authors.affiliation: First Department of Internal Medicine, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8666, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Matsukura
authors.forename: Fumio
authors.initials: F
authors.lastname: Kokubu
authors.forename: Hideki
authors.initials: H
authors.lastname: Kuga
authors.forename: Mio
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Koushi
authors.initials: K
authors.lastname: Ieki
authors.forename: Miho
authors.initials: M
authors.lastname: Odaka
authors.forename: Shintarou
authors.initials: S
authors.lastname: Suzuki
authors.forename: Shin
authors.initials: S
authors.lastname: Watanabe
authors.forename: Hiroko
authors.initials: H
authors.lastname: Takeuchi
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Adachi
authors.forename: Cristiana
authors.initials: C
authors.lastname: Stellato
authors.forename: Robert P
authors.initials: RP
authors.lastname: Schleimer
mesh_terms: D002461:Cell Line, Transformed; D054413:Chemokine CCL11; D019742:Chemokines, CC / Q000096:biosynthesis / Q000235:genetics*; D004357:Drug Synergism; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology; D005786:Gene Expression Regulation; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D020545:Respiratory Mucosa / Q000276:immunology*; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: C515456:CCL11 protein, human; D054413:Chemokine CCL11; D019742:Chemokines, CC; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma