Introduction of the interleukin-10 gene into mice inhibited bleomycin-induced lung injury in vivo

Interleukin (IL)-10 has been shown to reduce many inflammatory reactions. W e investigated the in vivo effects of IL-10 on a bleomycin-induced lung inj ury model. Hemagglutinating virus of Japan (HVJ)-liposomes containing a hum an IL-10 expression vector (hIL10-HVJ) or a balanced salt solution as a con trol (Cont-HVJ) was intraperitoneally injected into mice on day -3. This wa s followed by intratracheal instillation of bleomycin (0.8 mg/kg) on day 0. Myeloperoxidase activity of bronchoalveolar lavage fluid and tumor necrosi s factor-alpha mRNA expression in bronchoalveolar lavage fluid cells on day 7 and hydroxyproline content of the whole lung on day 21 were inhibited si gnificantly by hIL10-HVJ treatment. However, Cont-HVJ treatment could not s uppress any of these parameters. We also examined the in vitro effects of I L-10 on the human lung fibroblast cell line WI-38. IL-10 significantly redu ced constitutive and transforming growth factor-beta-stimulated type I coll agen mRNA expression. However, IL-10 did not affect the proliferation of WI -38 cells induced by platelet-derived growth factor. These data suggested t hat exogenous IL-10 may be useful in the treatment of pulmonary fibrosis.