Altered gut bacterial-fungal interkingdom networks in children and adolescents with depression.

BACKGROUND: Most studies of the gut-brain axis have focused on bacteria; little is known about commensal fungi. Children and adolescents with depression were reported to have gut bacterial microbiota dysbiosis, but the role of the mycobiota has not been evaluated. METHODS: Faecal samples were obtained from 145 children and adolescents with depression and 110 age- and gender-matched healthy controls. We analysed the fungal microbiota, including in terms of their associations with the gut microbiota, and subjected the internal transcribed spacer 2 (ITS2) rRNA gene to mitochondrial sequencing. RESULTS: Our findings revealed unaltered fungal diversity, but altered taxonomic composition, of the faecal fungal microbiota in the children and adolescents with depression. Key fungi such as Saccharomyces and Apiotrichum were enriched in the depressed patients, while Aspergillus and Xeromyces showed significantly decreased abundance. Interestingly, the bacterial-fungal interkingdom network was markedly altered in the children and adolescents with depression, and mycobiome profiles were associated with different bacterial microbiomes. LIMITATION: The cross-sectional design precluded the establishment of a causal relationship between the gut mycobiota and the children and adolescents with depression. CONCLUSIONS: The gut mycobiome is altered in the children and adolescents with depression. Our findings suggest that fungi play an important role in the balance of the gut microbiota and may help identify novel therapeutic targets for depression.