RESUMO
Chronic hepatitis B virus (HBV) infection is the main cause of viral hepatitis, liver cirrhosis, and primary liver cancer. At present, nucleos(t)ide analogues (NUC) and pegylated interferon α used in clinical practice cannot directly target covalently closed circular DNA, and it is difficult to achieve clinical cure of chronic hepatitis B patients; therefore, it is urgently needed to develop direct-acting antiviral agents targeting all stages of the HBV replication cycle. Capsid assembly modulator (CpAM) targets the assembly of viral capsids through various mechanisms, thereby exerting a direct-acting antiviral effect. Its combination with NUC should have a good synergistic antiviral effect, but the results of existing clinical trials have shown that chronic hepatitis B patients who received a limited course of antiviral therapy with CpAM and NUC all experienced off-therapy viral rebound. Based on the mechanism of action of these two types of drugs, this article provides a reasonable explanation for the above clinical trial results and points out that a longer course of antiviral therapy with CpAM and NUC may be needed in the future clinical trials with safe drug withdrawal as the end point of observation, so as to deplete or silence the pool of covalently closed circular DNA and increase the possibility of safe drug withdrawal in CHB patients. In addition, further studies are needed to explore antiviral therapeutic strategies with a combination of multiple targets.
RESUMO
Objective@#To explore and analyze the possible mechanism of liver injury in patients with coronavirus disease 2019 (novel coronavirus pneumonia, NCP).@*Methods@#The correlation between ALT, AST and other liver enzyme changes condition and NCP patients’ disease status reported in the literature was comprehensively analyzed. ACE2 expression in liver tissue for novel coronavirus was analyzed based on single cell sequencing (GSE115469) data. RNA-Seq method was used to analyze Ace2 expression and transcription factors related to its expression in liver tissues at various time-points after hepatectomy in mouse model of acute liver injury with partial hepatectomy. t-test or Spearman rank correlation analysis was used for statistical analysis.@*Results@#ALT and AST were abnormally elevated in some patients with novel coronavirus infection, and the rate and extent of ALT and AST elevation in severe NCP patients were higher than those in non-severe patients. Liver tissue results of single cell sequencing and immunohistochemistry showed that ACE2 was only expressed in bile duct epithelial cells of normal liver tissues, and very low in hepatocytes. In a mouse model of acute liver injury with partial hepatectomy, Ace2 expression was down-regulated on the first day, but it was elevated up to twice of the normal level on the third day, and returned to normal level on seventh day when the liver recovered and hepatocyte proliferation stopped. Whether this phenomenon suggests that the bile duct epithelial cells with positive expression of Ace2 participate in the process of liver regeneration after partial hepatectomy deserves further study. In RNA-Seq data, 77 transcription factors were positively correlated with the expression of ACE2 (r > 0.2, FDR < 0.05), which were mainly enriched in the development, differentiation, morphogenesis and cell proliferation of glandular epithelial cells.@*Conclusion@#We assumed that in addition to the over activated inflammatory response in patients with NCP, the up-regulation of ACE2 expression in liver tissue caused by compensatory proliferation of hepatocytes derived from bile duct epithelial cells may also be the possible mechanism of liver tissue injury caused by 2019 novel coronavirus infection.