Fig. 4

Alpha diversity of the sputum microbiomes of different subtypes of AECOPD: eosinophilic vs non-eosinophilic (a), frequency of AECOPD (b), and sputum-eosinophilic vs non-eosinophilic (c). In AECOPD patients, we defined the subtypes based on clinical parameters. A: eosinophils subtype: blood eosinophils < 2% as non-eosinophilic (24 samples), blood eosinophils ≥2% as eosinophilic (9 samples). b: AECOPD frequency (0&1) (29 samples) and AECOPD frequency (2&3) (4 samples) based on the times having AECOPD in the past 1 year. c: sputum eosinophils < 3% as non-sputum-eosinophilic (26 samples), sputum eosinophils ≥3% sputum-eosinophilic (7 samples). AECOPD: acute exacerbations of chronic obstructive pulmonary disease. Both serum eosinophilic and sputum eosinophilic had no significant Shannon Index. The sputum microbiome of patients with 0 or 1 AECOPD had greater alpha diversity than those with 2 or 3 AECOPDs. The p values were calculated by using Wilcoxon test. AECOPD: acute exacerbations of chronic obstructive pulmonary disease