α- and β-diversity
Difference in airway microbiome was observed across cohorts at species
level in both α-diversity (p = 0.001, Figure 1B ) and
β-diversity (p ≤0.002, Figure 1C ). Although the levels of
α-diversity in SAn and SAs/ex were comparable, SAs/ex exhibited lower
α-diversity compared to MMA and HC. α-diversity of SAn was lower than
that of MMA while there was no difference between MMA and HC
(Figure 1B ). α-diversity was inversely correlated with sputum
neutrophils in SAn, neutrophilic and paucigranulocytic inflammation
groups, and in TAC1 and TAC3 (Figure S3). There was no positive
association between α-diversity and exacerbations in the previous year
or pack-years of smoking, but there was a positive correlation between
α-diversity, and FEV1 (% predicted) in neutrophilic inflammation and in
TAC2 (Figure S3 ).
Compared to HC, α-diversity was reduced in eosinophilic
(p<0.05), neutrophilic (p<0.05) and mixed
granulocytic (p<0.001) (Figure 2B ). Differences in
β-diversity based on Bray-Curtis dissimilarity were observed across the
inflammatory groups using PERMANOVA (p<0.001) and ordination
using principal coordinate analysis (Figure 2C) .
α-diversity in TAC1 and TAC2 was lower than in TAC3 and HC
(p<0.001) (Figure 3B) . Differences in β-diversity
based on Bray-Curtis dissimilarity were also observed across the TACs
(p<0.001) (Figure 3C) .