Lonicera japonica Attenuates Carbon Tetrachloride-Induced Liver Fibrosis in Mice: Molecular Mechanisms of Action

Liver fibrosis is a worldwide clinical issue that generally causes hepatic cirrhosis. Lonicerae Japonicae Flos (dried flower buds of Lonicera japonica Thunb) is a traditional heat-clearing and detoxifying herbal medicine in China. This study aims to observe the protection of the water extract of Lonicerae Japonicae Flos (FL) from carbon tetrachloride (CCl4)-induced liver fibrosis in mice. Liver fibrosis was induced in mice by intraperitoneal injection of 2 ml/kg CCl4 twice a week for 4 weeks. FL's attenuation of CCl4-induced liver fibrosis in mice was evidenced by the results of Masson's trichrome and Sirius red staining, liver hydroxyproline content and serum amount of collagen IV. FL reduced hepatic stellate cells (HSCs) activation and reversed the epithelial-mesenchymal transition (EMT) process in mice treated with CCl4. FL also alleviated liver oxidative stress injury and enhanced the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) anti-oxidant signaling pathway in mice treated with CCl4. Additionally, the main phenolic acids in FL including chlorogenic acid (CGA) and caffeic acid (CA) both reduced HSCs activation in vitro. In summary, FL attenuates CCl4-induced liver fibrosis in mice by inhibiting HSCs activation, reversing EMT and reducing liver oxidative stress injury via inducing Nrf2 activation. CGA may be the main active compound contributing to the antifibrotic activity of FL.