Effects of FGF-21 and Nrf2 on BLM-induced pulmonary fibrosis in mice

AIM:To investigate the effect of fibroblast growth factor-21 (FGF-21) on bleomycin (BLM)-induced inflammatory response and oxidative stress in the lung, and to further explore the molecular mechanism of FGF-21 against pulmonary fibrosis. METHODS:The lung fibrosis model was induced by BLM intratracheal instillation. A total of 40 mice were randomly divided into control group, BLM group, FGF-21 (1, 2 and 5 mg/kg)+BLM groups. Western blot was used to detected the protein expression of collagen I, fibronectin and nuclear factor E2-related factor 2 (Nrf2). The reactive oxygen species (ROS) production was measured by DCFH-DA staining. The levels of inflammatory cytokines were measured by ELISA. The content of malondialdehyde (MDA), the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx), and the content of hydroxyproline (HYP) were detected by commercially available assay kits. RESULTS:Treatment with FGF-21 notably attenuated BLM-induced the expression levels of inflammatory mediators tumor necrosis factor-α, interleukin-1β and interleukin-6 in the lung tissue. In addition, FGF-21 treatment remarkably reduced the generation of ROS and the content of MDA trigged by BLM, accompanied with the enhanced activity of anti-oxidative enzymes SOD and GPx (P<0.05). Furthermore, treatment with FGF-21 obviously reduced the extracellular matrix (ECM) accumulation by suppressing the expression of collagen I and fibronectin induced by BLM, accompanied with the decreases in the levels of TGF-β1 and HYP. Silencing of Nrf2 expression abolished the protective effect of FGF-21. CONCLUSION:FGF-21 relieves BLM-induced pulmonary fibrosis by reducing the inflammatory response, mitigating oxidative damage and decreasing the ECM deposition via Nrf2 activation, thus providing the basis for the therapeutic effect of FGF-21 on the lung fibrosis.