Data analysis
Data were downloaded from the tranSMART platform (16). We analysed the
gene expression of ACE2, TMPRSS2, and FURIN in the lower airway samples
obtained from asthmatics and healthy subjects. Gene expression levels
and inflammatory cell counts in sputum were log-transformed to normalize
their distribution. One-way ANOVA and Tukey’s multiple comparison tests
were utilized to examine differences of the gene expression levels of
ACE2, TMPRSS2 and FURIN across the 3 groups (SA, MMA and HV) or the 3
TACs (15). Linear regression analyses were used to examine baseline
demographic and clinical parameters in relation to each gene expression
level. Multivariate linear regressions were conducted to identify
baseline parameters significantly correlated with each gene expression
level, with adjustment for age, gender and any parameters showingp values < 0.05 in univariate analyses; when both
sputum and blood eosinophils (%) or neutrophils (%) showed pvalues < 0.05, sputum values were chosen for the multivariate
model. The Benjamini–Hochberg procedure controlled for false discovery
rate. Spearman’s rank correlation was used for correlation analysis.