FGF21 attenuates pulmonary fibrogenesis through ameliorating oxidative stress in vivo and in vitro

Pulmonary fibrosis (PF) is a chronic, progressive lung disease, characterized by excessive matrix formation, destruction of the normal lung architecture, dysfunction and finally death. Fibroblast growth factor 21 (FGF21) is a promising pleiotropic regulator in glucolipid metabolism. Recently, we reported that FGF21 attenuates hepatic fibrogenesis. However, the role of FGF21 on PF is unknown. In this study, mice endotracheal instilled with bleomycin (BLM) were used to study the effect of FGF21 on PF. Bleomycin-instilled mice were administered with pirfenidone (PFD) or FGF21 daily for 3 weeks from 7 days after instillation of BLM. Results showed FGF21 and PFD attenuated the dense deposition of collagen, intense infiltration of inflammatory cells and destruction of tissue architecture in lungs caused by BLM, and also alleviated the increased expression of TGF-β, Col I and α-SMA and decreased the expression of E-cadherin. At the same time, FGF21 also markedly reversed the activity of SOD and T-AOC, decreased the enhanced content of MDA and increased the expression of Nrf-2 in the lungs of BLM-treated mice. To further explore the mechanisms of FGF21 attenuate PF by amelioration of oxidative stress, we examined the effect of FGF21 in A549 cells treated with paraquat (PQ). A549 cells were incubated with PQ plus FGF21 or PFD for 48 h. The results showed that FGF21 and PFD reduced the expression of TGF-β, Col I and α-SMA and increased the expression of E-cadherin in PQ-treated A549 cells. FGF21 also suppressed oxidative stress in PQ-treated A549 cells, as evidenced by a decrease of the MDA level, a reversed activity of antioxidant enzymes and an increased expression of Nrf-2. We conclude that FGF21 inhibits pulmonary fibrosis through activating Nrf-2 pathway, subsequently suppressing oxidative stress, inhibiting ECM deposition and pulmonary fibrogenesis, suggesting that FGF21 has potential as therapeutic agent for treatment of pulmonary fibrosis.