Fig. 1

Co-occurrence network analysis of sputum microbiome between COPD and HC. A, B. Comparison of beta diversity (weighted UniFrac distance) and alpha diversity (Shannon index, Mann–Whitney U-test) between COPD and HC in the EndAECOPD cohort (n = 187) (A) and the SRP066375 cohort (n = 190) (B). C, D. Co-occurrence network maps of COPD and HC illustrating identified microbial interactions in EndAECOPD (C) and SRP066375 (D). Each node represents a microbe and microbial interactions are illustrated by connecting edges. The number of interactions for a microbe is calculated as degree. Node size is proportional to the number of interactions for each microbe. Selected taxa of clinical relevance are noted with white color. E. Comparison of key network parameters illustrating node and edge characteristics respectively between COPD and HC in both cohorts. Degree, betweenness centrality, and stress centrality were compared between COPD and HC by Mann–Whitney U-test. Percent of negative interactions, i.e. total number of negative interactions as a proportion of total interactions, were compared by χ² test. F, G. Visualization of the opposing network by displaying positive and negative interactions between the most abundant taxa in COPD and HC in EndAECOPD (F) and SRP066375 cohort (G). Edge transparency is proportional to interaction strength between microbes in terms of edge weights. Negative interactions are classified if the sign of the edge weights is negative, and vice versa. # denotes paraphyletic group; • denotes unclassified genus; •• denotes classified but unnamed genus