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.[1]References
- Regulatory mechanisms of Th2 cytokine-induced eotaxin-3 production in bronchial epithelial cells: possible role of interleukin 4 receptor and nuclear factor-kappaB. Kobayashi, I., Yamamoto, S., Nishi, N., Tsuji, K., Imayoshi, M., Inada, S., Ichiamaru, T., Hamasaki, Y. Ann. Allergy Asthma Immunol. (2004) [Pubmed]
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