Nuclear Factor Kappa B Mediates Interleukin–8 Production in Eosinophils

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Abstract
Background: Recent reports indicate that in response to various stimuli, eosinophils produce a variety of cytokines (e.g. IL–8) which play pivotal roles in allergic inflammation. In that regard, the transcription factor, nuclear factor, Kappa B (NF–κB), is an important activator of tumor–necrosis–factor–alpha (TNF–α)–induced IL–8 gene expression in monocytes, lymphocytes and neutrophils. We therefore investigated the role played by NF–κB in cytokine production induced by stimulation of eosinophils with the proinflammatory cytokines, granulocyte–monocyte colony–stimulating factor (GM–CSF) and TNF–α. Methods: Peripheral blood samples were obtained from human subjects with slight to moderate eosinophilia. NF–κB activation elicited by exposing cells to GM–CSF and/or TNF–α was investigated using immunohistochemistry and gel shift assays. To functionally assess the effects of NF–κB translocation, IL–8 production was also examined using an enzyme–linked immunosorbent assay. Results: Stimulation of eosinophils with GM–CSF + TNF–α induced significant increases in the synthesis and secretion of IL–8 which were associated with translocation of NF–κB p50 into the nucleus. The binding of NF–κB to the DNA was verified by the gel shift assays. IL–8 production was significantly inhibited by N–acetyl–L–cysteine, FK506 and MG–132, inhibitors of NF–κB activation and translocation. Conclusion: On the basis of our findings, we conclude that activation and translocation of NF–κB plays a crucial role in the signal–transduction pathway leading to the synthesis and release of IL–8 by eosinophils.