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

• Published in: Biochemical and biophysical research communications Vol. 577; pp. 146 - 151
• Main Authors: Sasaki, Michihito, Kishimoto, Mai, Itakura, Yukari, Tabata, Koshiro, Intaruck, Kittiya, Uemura, Kentaro, Toba, Shinsuke, Sanaki, Takao, Sato, Akihiko, Hall, William W., Orba, Yasuko, Sawa, Hirofumi
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 05.11.2021
• Subjects: A549 Cells; A549 cells; ACE2; Air-liquid interface; Alveolar Epithelial Cells - pathology; Alveolar Epithelial Cells - virology; Cell Culture Techniques - methods; Cells, Cultured; COVID-19 - virology; Disease Susceptibility; epithelium; Gene Expression Regulation, Neoplastic; Humans; interphase; liquid-air interface; lungs; mucus; Peptidyl-Dipeptidase A - genetics; Peptidyl-Dipeptidase A - metabolism; phenotype; SARS-CoV-2; SARS-CoV-2 - physiology; Serine Endopeptidases - genetics; Serine Endopeptidases - metabolism; Severe acute respiratory syndrome coronavirus 2; TMPRSS2; Up-Regulation - genetics; Viral entry; A549 cells; ACE2; Viral entry; TMPRSS2; SARS-CoV-2; Air-liquid interface
• ISSN: 0006-291X; 1090-2104; 1090-2104
• DOI: 10.1016/j.bbrc.2021.09.015

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. •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.