- Type I interferons (IFNs) consist of a group of structurally similar cytokines that play an integral role in regulating the immune response to combat lung infections. In certain models type I IFNs have also been associated with suppression of Th2-skewed immune and inflammatory responses. Transient pulmonary overexpression of the gp130 cytokine Oncostatin M (OSM) by Adenovirus vector (AdOSM) induces a robust Th2-skewed cytokine/inflammatory profile in C57Bl/6 murine lungs. In this study we assessed type I IFN function in OSM-mediated inflammation in vivo using Ifnar1-/- C57Bl/6 mice and Ifnar1-deficient cells in vitro. Ifnar1-/- mice showed a significant reduction in AdOSM-induced histopathology (epithelial hyperplasia, alveolar septal wall thickening, cellular infiltration), and levels of IL-6 and chemokine protein (CXCL-1/KC and CCL24/eotaxin-2) in lungs compared with wild-type. Ifnar1-/- murine fibroblasts and human type I IFN receptor (Ifnar)-knockdown fibroblasts were also less responsive to OSM in STAT3 activation and cytokine production compared with Ifnar-sufficient cells in vitro. Exogenous type I IFN induced IL-6 responses in mouse and human fibroblasts and in combination with OSM further stimulated IL-6 production, suggesting a concerted action of type I IFNs and OSM. Taken together, these results demonstrate that cross-talk between IFNAR and OSM signaling enhances cell responses and modulates OSM-driven responses in lung inflammation.