ACE2 and COVID-19: In regard to COVID-19, SARS-CoV-2 triggers AHR signalling upon ACE2-mediated cellular entry, leading to mucin hypersecretion and suppression of key antiviral pathways, particularly type I interferon (IFN-I) and NF-κB signalling, thereby promoting viral persistence and respiratory pathology (9, 31, Figure 3).