Does type 2 airway inflammation protect against
COVID-19?
Allergic airway disease patients appear to be underrepresented among
COVID-19 patients. This could be partly attributed to the low ACE2
expression detected in allergic patients, with or without concomitant
asthma.46 Furthermore, allergen challenge, which
induces T helper (Th)-2 inflammation, has been shown to reduced ACE2
expression in a murine model of asthma, and ACE2 expression was
inversely associated with type 2 biomarkers (IL-13, IgE, exhaled nitric
oxide fraction).47 These results are in line with
previous work showing that decreased ACE expression in the airway
epithelium of asthmatic subjects was associated with eosinophilic
inflammation.48 Altogether, these data suggest that
type 2 airway inflammation may reduce the susceptibility of SARS-CoV-2
infection by reduction of ACE2 expression.