Regulatory mechanisms of Th2 cytokine-induced eotaxin-3 production in bronchial epithelial cells: possible role of interleukin 4 receptor and nuclear factor-kappaB.
BACKGROUND
Several cytokine combinations have been shown to induce eotaxins in bronchial epithelium. The mechanism for differential regulation of eotaxin expression remains unclear.


OBJECTIVE
To investigate the regulatory mechanisms of eotaxin-3 production vs eotaxin-1 production in cultured bronchial epithelium.


METHODS
Messenger RNA (mRNA) expression levels of eotaxin-1, eotaxin-2, and eotaxin-3 in a human bronchial epithelial cell line (BEAS-2B) and a normal human bronchial epithelial cell were examined using reverse transcriptase-polymerase chain reaction. Protein production was determined by enzyme-linked immunosorbent assay. Receptor expression was examined by flow cytometry. Phosphorylation of signal transducer and activator of transcription factor 6 (STAT6) was examined by immunoblotting.


RESULTS
Eotaxin-1 and eotaxin-3, but not eotaxin-2, mRNA expressions were induced by stimulation with interleukin (IL) 13 or IL-4. However, eotaxin-3 was the only protein detected after stimulation. A consistent 10-fold difference in the potency of IL-13- and IL-4-mediated induction of eotaxin-3 mRNA expression was observed. Interleukin 4 induced more potent induction of STAT6 phosphorylation compared with IL-13. The BEAS-2B cells were observed to express types 1 and 2 IL-4 receptors. Pretreatment with tumor necrosis factor a enhanced IL-4-induced eotaxin-1, but not eotaxin-3, mRNA expression. An inhibitor of nuclear factor-KB inhibited IL-13- and IL-4-induced eotaxin-1 gene expressions. However, it enhanced eotaxin-3 gene expression.


CONCLUSIONS
These results suggest that differences in the potency of IL-13- and IL-4-mediated induction of eotaxin-3 might be explained by expression of types 1 and 2 IL-4 receptors in bronchial epithelium. Differences in eotaxin-1 and eotaxin-3 mRNA and protein expression might be due to differential effects of nuclear factor-kappaB on gene expression.
Kobayashi
Ikuko
I
Department of Pediatrics, School of Medicine, Saga University, Saga, Japan.
Yamamoto
Shuichi
S
Nishi
Natsuko
N
Tsuji
Kohsuke
K
Imayoshi
Miyoko
M
Inada
Shigeyasu
S
Ichiamaru
Tomohiro
T
Hamasaki
Yuhei
Y
D001980:Bronchi / Q000166:cytology*; D002478:Cells, Cultured; D054413:Chemokine CCL11; D054423:Chemokine CCL24; D000075906:Chemokine CCL26; D019742:Chemokines, CC / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D006801:Humans; D018793:Interleukin-13 / Q000276:immunology / Q000494:pharmacology*; D015847:Interleukin-4 / Q000276:immunology / Q000494:pharmacology*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019948:Receptors, Interleukin-4 / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology
C515456:CCL11 protein, human; C515484:CCL24 protein, human; C120429:CCL26 protein, human; D054413:Chemokine CCL11; D054423:Chemokine CCL24; D000075906:Chemokine CCL26; D019742:Chemokines, CC; D018793:Interleukin-13; D016328:NF-kappa B; D012333:RNA, Messenger; D019948:Receptors, Interleukin-4; D015847:Interleukin-4