Fig. 4
Aberrant gut microbiome in CCHD patients is associated with gut barrier impairment and systemic inflammation. A PCoA of the Bray–Curtis distances based on bacterial composition at the species level revealed significant differences between the CCHD-P and CCHD-G subgroups (PERMANOVA). Bacterial taxa that significantly correlated with the PC-axes with Spearman’s correlation coefficient >  + 0.4 or <  − 0.4 (with a maximum of the top six for each quadrant) are graphed as contributors that drive the separation, and the length of the arrow represents the degree of correlation to the PC-axes. The distribution and density of samples projected onto PC-axes are displayed in violin plots and assessed individually using the Wilcoxon rank sum test. B Heatmap of discriminative bacterial species between CCHD-P and CCHD-G subgroups. C Co-occurrence network deduced from bacterial taxa differentially enriched in the CCHD-P and CCHD-G subgroups. The size of each node is proportional to the mean relative abundance. Red edges indicate positive correlation and blue edges indicate negative correlation (Spearman, P < 0.05, r > 0.4). D PCoA based on the relative abundance of the KEGG orthology groups revealed significant differences in the microbial functionality between CCHD-P and CCHD-G subgroups (PERMANOVA). Dashed lined ellipses indicate 95% confidence interval (CI) of datapoints. E LDA showing discriminative KEGG metabolic pathways between CCHD-P and CCHD-G subgroups. F Correlation circle plot showing associations between multiple categories of variables (including the relative abundance of bacterial species, KEGG metabolic pathways, and biomarkers of intestinal permeability and systemic inflammation), as measured via canonical correlations. Neighboring of variables indicates correlations between variables. **P < 0.01; NS, not significant; CCHD-G, CCHD patients with good prognosis; CCHD-P, CCHD patients with poor prognosis; PCoA, principal coordinates analysis; LDA, linear discriminant analysis; GBD, gut barrier dysfunction