Could SARS-CoV-2-induced lung injury be attenuated by vitamin D?

A novel coronavirus (severe acute respiratory syndrome coronavirus 2, SARS-CoV-2) has been confirmed as having the capacity to transmit from humans to humans, causing acute respiratory distress syndrome (ARDS) and acute lung injury. Angiotensin converting enzyme-2 (ACE2) is known to be expressed on type II pneumocytes. As a counter-regulatory arm of the renin-angiotensin system (RAS), ACE2 plays critical roles in the pathogenesis of ARDS and acute lung injury. The affinity of the spike protein receptor binding domain (RBD) of SARS-CoV-2 for human ACE2 (hACE2) largely determines the degree of clinical symptoms after infection by SARS-CoV-2. Previous studies have shown that regulating the ACE2/RAS system is effective in the treatment of severe acute respiratory syndrome coronavirus (SARS-CoV)-induced ARDS and acute lung injury. Since ACE2 is the host cell receptor for both SARS-CoV-2 and SARS-CoV, regulating the ACE2/RAS system may alleviate ARDS and acute lung injury caused by SARS-CoV-2 as well as SARS-CoV. Vitamin D was found to affect ACE2, the target of SARS-CoV-2; therefore, we propose that vitamin D might alleviate ARDS and acute lung injury induced by SARS-CoV-2 by modulating ACE2.