Differential regulation of eotaxin expression by IFN-gamma in airway epithelial cells.
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.
Matsukura
Satoshi
S
First Department of Internal Medicine, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8666, Japan.
Kokubu
Fumio
F
Kuga
Hideki
H
Kawaguchi
Mio
M
Ieki
Koushi
K
Odaka
Miho
M
Suzuki
Shintarou
S
Watanabe
Shin
S
Takeuchi
Hiroko
H
Adachi
Mitsuru
M
Stellato
Cristiana
C
Schleimer
Robert P
RP
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
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