Baicalein inhibits hepatitis B virus through the coiled coil domain containing protein 88A (CCDC88A)-dependent autophagy pathway

Abstract

Background

Chronic infection with the hepatitis B virus (HBV) represents a significant global health concern. Baicalein, a naturally occurring flavone derived from the roots of Scutellaria baicalensis Georgi, has exhibited both anti-inflammatory and antiviral activities. S. baicalensis is extensively utilized in traditional Chinese medicine for the treatment of various liver disorders, including hepatitis. However, the specific anti-HBV effects of baicalein have not been fully elucidated.

Purpose

This study aimed to investigate the inhibitory effects of baicalein on HBV and to elucidate its underlying mechanisms.

Materials and Methods

The levels of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) were measured using enzyme-linked immunosorbent assay (ELISA) kits. Quantification of HBV DNA was performed using quantitative real-time polymerase chain reaction (qRT-PCR). Western blot analysis was conducted to evaluate proteins involved in autophagy, lysosomal acidification, and autophagy-related signaling pathways. Immunofluorescence microscopy was utilized to assess autophagic flux and lysosomal acidification.

Results

Baicalein demonstrated significant inhibition of HBsAg, HBeAg, and HBV-DNA secretion in both in vivo and in vitro environments. Subsequent investigations revealed that baicalein disrupted the intracellular trafficking of the hepatitis B virus by inhibiting the CCDC88A-AKT-mTOR (Coiled coil domain containing protein 88A- protein kinase B-mammalian target of rapamycin) signaling pathway. Additionally, baicalein induced autophagy in HepG2 (Human hepatocellular carcinoma cell line 2) and HepG2.215 cell models. The anti-hepatitis B antigen effect of baicalein was partially attenuated when both early and late stages of autophagy were inhibited. A significant correlation was identified between the phosphorylation of AMPKα and the enhanced autophagy observed in baicalein-treated cells.

Conclusions

This study elucidates a novel mechanism by which baicalein inhibits the hepatitis B virus (HBV). Specifically, baicalein exerts its antiviral effects by activating autophagy and suppressing the CCDC88A-AKT-mTOR signaling pathway.