ACE2 and COVID-19: The SARS-CoV-2 spike protein enhanced the expression of ACE2 in Beas-2B cells, and the cytokines IL-4 and IL-13 were repressed, whreas TNF-α, IL-12, and IL-17 increased ACE2 expression in Beas-2B cells, which reflects the different risks of severe COVID-19 (Song et al., 2021; Zhou et al., 2021).