A novel strain of coronoviridae (SARS-CoV-2) was reported in Wuhan China in December 2019. Initially, infection presented with a broad spectrum of symptoms which typically included muscle aches, fever, dry cough, and shortness of breath. SARS-CoV-2 enters cells via ACE2 receptors which are abundant throughout the respiratory tract. However, there is evidence that these receptors are abundant throughout the body, and just as abundant in cholangiocytes as alveolar cells, posing the question of possible direct liver injury. While liver enzymes and function tests do seem to be deranged in some patients, it is questionable if the injury is due to direct viral damage, drug-induced liver injury, hypoxia, or microthromboses. Likely, the injury is multifactoral, and management of infected patients with pre-existing liver disease should be taken into consideration. Ultimately, a vaccine is needed to aid in reducing cases of SARS-CoV-2 and providing immunity to the general population. However, while considering the types of vaccines available, safety concerns, particularly of RNA- or DNA-based vaccines, need to be addressed.

The gut–liver axis is defined by dietary and environmental communication between the gut, microbiome and the liver with its redox and immune systems, the overactivation of which can lead to hepatic injury. We used media preconditioning to mimic some aspects of the enterohepatic circulation by treating the human Caco-2 intestinal epithelial cell line with 5, 10 and 20 mM paracetamol (N-acetyl-para-aminophenol; APAP) for 24 h, after which cell culture supernatants were transferred to differentiated human hepatic HepaRG cells for a further 24 h. Cell viability was assessed by mitochondrial function and ATP production, while membrane integrity was monitored by cellular-based impedance. Metabolism by Caco-2 cells was determined by liquid chromatography with tandem mass spectrometry. Caco-2 cell viability was not affected by APAP, while cell membrane integrity and tight junctions were maintained and became tighter with increasing APAP concentrations, suggesting a reduction in the permeability of the intestinal epithelium. During 24 h incubation, Caco-2 cells metabolised 64–68% of APAP, leaving 32–36% of intact starting compound to be transferred to HepaRG cells. When cultured with Caco-2-preconditioned medium, HepaRG cells also showed no loss of cell viability or membrane integrity, completely in contrast to direct treatment with APAP, which resulted in a rapid loss of cell viability and membrane integrity and, ultimately, cell death. Thus, the pre-metabolism of APAP could mitigate previously observed hepatotoxicity to hepatic tight junctions caused by direct exposure to APAP. These observations could have important implications for the direct exposure of hepatic parenchyma to APAP, administered via the intravenous route.