ACE2 and COVID-19: Several small molecules and FDA-approved drugs, such as short-chain fatty acids (SCFAs), ursodeoxycholic bile acid (UDCA), UDCA combined with dihydroartemisinin (DHA), corticosteroids and fluticasone propionate, have been reported to prevent SARS-CoV-2 infection through the reduction of ACE2 expression in various cells, tissues and organs.6–8 Therefore, identifying new regulatory factors that modulate ACE2 expression holds great promise for the development of drugs and vaccines for the treatment of COVID-19.