Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has caused current coronavirus disease 2019 (COVID-19) pandemic. Despite a preferential respiratory tropism of SARS-CoV-2, multi-organ involvement has been demonstrated. Several studies suggest that SARS-CoV-2 triggers direct hepatic impairment in COVID-19 patients. SARS-CoV-2 entry into host cells is facilitated by host factors angiotensin converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). Interestingly, primary human hepatocytes (PHH) also express ACE2 and TMPRSS2. Despite this, convincing data on infection and factors modulating SARS-CoV-2 infection in PHH are lacking. Therefore, we aimed to demonstrate whether SARS-CoV-2 infects PHH in vitro and whether so called microRNAs (miRNAs), which are a class of small non-coding RNAs, have the potential to modulate SARS-CoV-2 infection in PHH.

We used PHH from cholangiocarcinoma patients for infection with SARS-CoV-2 in vitro. We selected candidate miRNAs targeting ACE2 and TMPRSS2 using in silico approaches and literature search. To unravel the potential regulatory mechanism, we performed miRNA transfection experiments, qRT-PCRs, western blots and luciferase reporter assays.

We could demonstrate that PHH can be readily infected with SARS-CoV-2. We identified that miR-200c-3p and miR-429 downregulate ACE2 while let-7c-5p suppresses TMPRSS2 in PHH. All candidate miRNAs seem to reduce SARS-CoV-2 burden in PHH either by downregulating ACE2 and TMPRSS2 or by potentially targeting the viral genome.

Our findings provide the first evidence of applicability of miRNAs in modulating SARS-CoV-2 infection in PHH. Our study may serve as an avenue for further studies towards miRNA-dependent therapeutics for the treatment of COVID-19.