Fluorofenidone attenuates pulmonary inflammation and fibrosis via inhibiting the IL-11/MEK/ERK signaling pathway

Background: Idiopathic pulmonary fibrosis (IPF) is a special type of interstitial lung diseases with unknown cause. Interleukin (IL)-11 is a new therapeutically target for fibrosis diseases. In this experiment, we further explored the pharmacology mechanism and molecular target of fluorofenidone (FD) in vivo and in vitro. Methods: Male C57BL/6J mice were intratracheally injected with Bleomycin (BLM) or saline. FD was administered throughout the course of the experiment. Lung tissue sections were stained with haemotoxylin and eosin, Masson’s trichrome and Immunohistochemistry. Cytokines were measured by ELISA, and phosphorylated extracellular signal-regulated kinase (p-ERK), phosphorylated mitogen-activated protein kinase (p-MEK), IL-11RA and gp130 were measured by Western blot. The RAW264.7 cells and the normal human lung fibroblasts (NHLFs) were treated with IL-11 and/or FD, IL-11RA-siRNA, MEK Inhibitor. The expressions of p-ERK, p-MEK, IL-11RA, gp130, α-SMA, fibronectin and collagenⅠwere measured by Western blot and/or RT-PCR, the cytokines were measured by ELISA. Results: FD attenuated pulmonary inflammation and fibrosis, and decreased the expressions of IL-8, IL-18, IL-11, MCP-1, p-ERK and p-MEK in the bleomycin mouse model. Moreover, the protein expressions of IL-11RA and gp130 were inhibited by FD in IL-11-induced RAW264.7 cells. Additionally, FD attenuated IL-11-induced expressions of p-ERK and p-MEK in IL-11-induced RAW264.7 cells and IL-11-induced normal human lung fibroblasts. Meanwhile, FD reduced IL-11-induced the levels of IL-8, IL-18 and MCP-1, blocked IL-11-induced the activation of fibroblasts. Conclusion: These findings demonstrated that FD attenuates BLM-induced pulmonary inflammation and fibrosis in mice via inhibiting the IL-11/MEK/ERK signaling pathway.