Autophagy inhibition attenuates the induction of anti-inflammatory effect of catalpol in liver fibrosis

Abstract Autophagy has been regarded as an inflammation-associated defensive mechanism against chronic liver disease, which has been highlighted as a novel therapeutic target for the treatment of liver fibrosis. We herein aimed to study the effects of catalpol on liver fibrosis in vivo and in vitro , and to elucidate the role of autophagy in catalpol-induced anti-inflammation. Catalpol protected the liver against CCl 4 -induced injury, as evidenced by mitigated hepatic steatosis, necrosis, and fibrotic septa. Catalpol decreased the serum levels of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase and bilirubin as well as the liver/body weight ratio. Masson and sirius red staining along with hydroxyproline detection showed that catalpol decreased collagen deposition significantly compared to that of the model group. Catalpol inhibited CCl 4 -induced liver fibrosis, manifested as decreased expressions of α-SMA, fibronectin and α1(I)-procollagen at both transcriptional and translational levels. Inflammatory factors, such as IL-1β, TNF-α, IL-18, IL-6 and COX-2, were significantly elevated in rats receiving CCl 4 and down-regulated by catalpol in a dose-dependent manner in vivo . Western blot and immunofluorescence assay revealed that catalpol activated the autophagy of rats with CCl 4 -caused liver fibrosis, as indicated by up-regulation of LC3-II and beclin1 and down-regulation of P62. The results of in vitro experiments were consistent. Interestingly, inhibition or depletion of autophagy by LY294002 or Atg5 siRNA significantly attenuated catalpol-induced anti-inflammatory effects on activated hepatic stellate cells in vitro . In conclusion, catalpol relieved liver fibrosis mainly by inhibiting inflammation, and autophagy inhibition attenuated the catalpol-induced anti-inflammatory effect on liver fibrosis.