Fig. 1

Comparison of ACE2, TMPRSS2 and FURIN gene expression levels (box-and-whisker plots showing median and interquartile range) between healthy volunteers and asthmatics in different airway compartments. ACE2 (a, d, g), TMPRSS2 (b, e, h) and FURIN (c, f, i) mRNA expression was assessed in sputum (a–c), bronchial brushings (d–f), and bronchial biopsies (g–i) compartments from healthy volunteers and asthmatics of different severity. SA severe asthmatics, MMA mild-to-moderate asthmatics, HV healthy volunteers, ns not significant (p > 0.05). P values were determined by one-way ANOVA and Tukey’s multiple comparison tests