Post-COVID metabolic enzyme alterations in K18-hACE2 mice exacerbate alcohol-induced liver injury through transcriptional regulation.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses a significant threat to global public health. Despite reports of liver injury during viral disease, the occurrence and detailed mechanisms underlying the development of secondary exogenous liver injury, particularly in relation to changes in metabolic enzymes, remain to be fully elucidated. Therefore, this study was aimed to investigate the mechanisms underlying SARS-CoV-2-induced molecular alterations in hepatic metabolism and the consequent secondary liver injury resulting from alcohol exposure. We investigated the potential effects of SARS-CoV-2 infection on alcohol-induced liver injury in Keratin 18 promoter-human angiotensin converting enzyme 2 (K18-hACE2) transgenic mice. Mice were intranasally infected with 1 × 10² PFU of SARS-CoV-2. Following a 14 d recovery period from infection, the recovered mice were orally administered alcohol at 6 g/kg. Prior SARS-CoV-2 infection aggravated alcohol-induced liver injury based on increased alanine aminotransferase levels and cytoplasmic vacuolation. Interestingly, infected mice exhibited lower blood alcohol levels and higher levels of acetaldehyde, a toxic alcohol metabolite, compared to uninfected mice after the same period of alcohol consumption. Along with alterations of several metabolic process-related terms identified through RNA sequencing, notably, upregulation of cytochrome P450 2E1 (CYP2E1) and CYP1A2 was observed in infected mice compared to control value prior to alcohol exposure, with no significant impact of SARS-CoV-2 on intestinal damage. Tumor necrosis factor-alpha persistently showed upregulated expression in the infected mice; it also enhanced aryl hydrocarbon receptor and Sp1 expressions and their binding activity to Cyp1a2 and Cyp2e1 promoters, respectively, in hepatocytes, promoting the upregulation of their transcription. Our findings suggest that SARS-CoV-2 infection exacerbates alcohol-induced liver injury through the transcriptional activation of Cyp1a2 and Cyp2e1, providing valuable insights for the development of clinical recommendations on long COVID.