Air-liquid interphase culture confers SARS-CoV-2 susceptibility to A549 alveolar epithelial cells

https://doi.org/10.1016/j.bbrc.2021.09.015Get rights and content

Highlights

  • A549 cells are resistant to SARS-CoV-2 infection in conventional submerged culture condition.

  • A549 cells showed susceptibility to SARS-CoV-2 infection in air-liquid interface culture condition.

  • Air-liquid interface culture upregulated the expression levels of ACE2 and TMPRSS2 in A549 cells.

Abstract

The human lung cell A549 is susceptible to infection with a number of respiratory viruses. However, A549 cells are resistant to Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) infection in conventional submerged culture, and this would appear to be due to low expression levels of the SARS-CoV-2 entry receptor: angiotensin-converting enzyme-2 (ACE2). Here, we examined SARS-CoV-2 susceptibility to A549 cells after adaptation to air-liquid interface (ALI) culture. A549 cells in ALI culture yielded a layer of mucus on their apical surface, exhibited decreased expression levels of the proliferation marker KI-67 and intriguingly became susceptible to SARS-CoV-2 infection. We found that A549 cells increased the endogenous expression levels of ACE2 and TMPRSS2 following adaptation to ALI culture conditions. Camostat, a TMPRSS2 inhibitor, reduced SARS-CoV-2 infection in ALI-cultured A549 cells. These findings indicate that ALI culture switches the phenotype of A549 cells from resistance to susceptibility to SARS-CoV-2 infection through upregulation of ACE2 and TMPRSS2.

Keywords

SARS-CoV-2
A549 cells
Air-liquid interface
ACE2
TMPRSS2
Viral entry

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