abstract
- Oncostatin M (OSM), a pleiotropic cytokine and a member of the gp130/IL-6 cytokine family, has been implicated in regulation of various chronic inflammatory processes. Previous work has shown that OSM induces eosinophil accumulation in mouse lungs in vivo and stimulates the eosinophil-selective chemokine eotaxin-1 synergistically with IL-4 in vitro. To examine the role of receptor regulation by OSM in synergistic eotaxin-1 responses, we here examine the modulation of the type-II IL-4 receptor (IL-4Ralpha and IL-13Ralpha1) by OSM and other gp130/IL-6 cytokine family members using NIH3T3 fibroblasts and primary mouse lung fibroblasts. We first show that OSM with either IL-13 or IL-4 synergistically induces eotaxin-1 expression in a dose-dependent fashion. Analysis of IL-4Ralpha expression at the protein (Western blot and FACS) and RNA (TAQMAN) levels showed that OSM markedly elevates expression by 3 h. OSM enhanced IL-13Ralpha1 mRNA and induced a smaller but detectable increase in total IL-13Ralpha1 protein. Priming fibroblasts with OSM for 6 h markedly enhanced subsequent IL-13 and IL-4-induced eotaxin-1 responses and STAT6 tyrosine-641 phosphorylation. Regulation of IL-4Ralpha by OSM was sensitive to inhibition of the PI3'K pathway by LY294002. These studies provide novel mechanistic insights in OSM role in regulation of synergistic eotaxin-1 responses and IL-4Ralpha expression in fibroblasts.