ACE2 and COVID-19: Angiotensin-converting enzyme 2 (ACE2), which is highly expressed on IECs, is a receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected cells and has an important effect on the occurrence and development of coronavirus disease 2019 (COVID-19) (Lamers et al., 2020; Ziegler et al., 2020).