Molecular and cellular mechanisms of liver dysfunction in COVID-19

Liver injury has been reported as a common complication in Coronavirus disease 2019 (COVID-19). Recently, more and more studies reported that the degree of liver damages was associated with the severity of COVID-19. Although the exact mechanism of liver injury in COVID-19 patients is unknown, recent studies have made some explorations and investigations. In this review, we summarized the potential mechanisms of liver dysfunction in COVID-19 patients gleaned from recently published research reports, which suggested that the progression of pre-existing liver diseases, direct damage of liver by SARS-CoV-2, systemic inflammation caused by SARS-CoV-2 infection, anti-viral drug toxicity, and hypoxia-reperfusion may be associated with liver injury in patients with COVID-19. Hypoxic liver injury due to ischemia and shock, cholestasis-related liver injury due to altered bile metabolism, and hepatocellular injury due to drug toxicity or overwhelming inflammation might occur in severe COVID-19 patients with sepsis. To understand the pathogenesis of liver dysfunction in COVID-19 patients, further research is needed to focus on liver-related comorbidities, the evidence of viral replication in hepatocytes and bile duct cells, histological features of liver injury, and the influence of hepatotoxic antiviral drugs. We also suggested that special attention should be paid to monitoring inflammatory cytokines and hypoxia for the prevention and treatment of liver injury in severe COVID-19 patients. A deep understanding of the mechanism of liver injury is helpful for the management and treatment of COVID-19 patients.