Effect and mechanism of IL-6 induced by M2 macrophages on the lung fibroblasts activation

Idiopathic pulmonary fibrosis (IPF) is usually accompanied with inflammatory response, especially the macrophages. The co-culture model of macrophages and fibroblast, and IPF mice model induced by bleomycin were used here to explore the role of macrophages and interleukin-6 (IL-6) in IPF. All animals welfare and experiments were performed following the regulations of the Animal Ethics Committee of Tianjin University of Traditional Chinese Medicine. The results showed that the content of IL-6 in IPF mice induced by bleomycin was significantly increased, and there was a large amount of inflammatory cell infiltration in the lungs. The results of wound-healing and immunofluorescence showed that alternative activated (M2) macrophages could induce the migration and activation of fibroblasts at 36 h, and the expression of IL-6 was increased in the co-culture system. The results of wound-healing and sirius red assay proved that IL-6 could induce the migration and activation of fibroblast. The results showed that M2 macrophages induced fibroblasts to secrete IL-6, thereby inducing the activation and migration of fibroblast, which affect the development of IPF.