Eosinophil granule-derived major basic protein induces IL-8 expression in human intestinal myofibroblasts

Eosinophil infiltration occurs in a variety of allergic and inflammatory di seases, The release of preformed mediators From eosinophils may contribute to inflammatory responses. We investigated the ability of eosinophil-derive d major basic protein and eosinophil-derived neurotoxin to stimulate produc tion of IL-8 from intestinal myofibroblasts. Intestinal myofibroblasts (18- Co cells) were incubated with major basic protein, eosinophil-derived neuro toxin, or a synthetic analogue of major basic protein, poly-L-arginine. Imm unoreactive IL-g was measured by ELISA and IL-8 mRNA levels were analysed b y Northern blot or reverse transcription-polymerase chain assay. Major basi c protein induced IL-8 mRNA production and release of significant levels of IL-8 immunoreactive protein. By contrast, eosinophil-derived neurotoxin st imulated little IL-8 release. The induction of IL-8 mRNA by poly-L-arginine was significantly inhibited by actinomycin D. These findings demonstrate a novel interaction between eosinophils and intestinal fibroblasts that may be involved in the pathogenesis of diseases associated with tissue eosinoph ilia.