Chlorogenic Acid Inhibited Epithelial–Mesenchymal Transition to Treat Pulmonary Fibrosis through Modulating Autophagy

Chlorogenic acid (CGA), derived from dicotyledons and ferns, has been demonstrated with anti-inflammatory, anti-bacterial, and free radical-scavenging effects and can be used to treat pulmonary fibrosis (PF). However, the specific mechanism by which CGA treats PF needs to be further investigated. In this study, in vivo experiment was firstly performed to evaluate the effects of CGA on epithelial–mesenchymal transition (EMT) and autophagy in bleomycin (BLM)-induced PF mice. Then, the effects of CGA on EMT and autophagy was assessed using transforming growth factor beta (TGF-β) 1-induced EMT model in vitro. Furthermore, autophagy inhibitor (3-methyladenine) was used to verify that the inhibitory mechanism of CGA on EMT was associated with activating autophagy. Our results found that 60 mg/kg of CGA treatment significantly ameliorated lung inflammation and fibrosis in mice with BLM-induced PF. Besides, CGA inhibited EMT and promoted autophagy in mice with PF. In vitro studies also demonstrated that 50 µM of CGA treatment inhibited EMT and induced autophagy related factors in TGF-β1-induced EMT cell model. Moreover, the inhibitory effect of CGA on autophagy and EMT in vitro was abolished after using autophagy inhibitor. In conclusion, CGA could inhibit EMT to treat BLM-induced PF in mice through, activating autophagy.