PADI4 and COVID-19: The PAD4 inhibitors (such as Cl-amidine and GSK484) prevent NETosis by reducing histone citrullination in the treatment of severe inflammatory diseases.226 Sivelestat, a potent NE inhibitor approved in Korea and Japan, can ameliorate acute lung injury.227 A retrospective cohort study showed that sivelestat exhibited positive outcomes in patients with ARDS,228 indicating that NE inhibitor might be beneficial for patients with COVID-19.