Age-stratification reveals age-specific intestinal microbiota signatures in juvenile idiopathic arthritis.

Objective: Juvenile Idiopathic Arthritis (JIA) comprises diverse chronic inflammatory conditions driven by malfunction of the immune system. The intestinal microbiota is considered a crucial environmental factor correlating with chronic inflammatory diseases, and for JIA certain alterations in the microbiota have already been described.

Methods: Here, we have characterized intestinal microbiota samples from 54 JIA patients and 38 pediatric healthy controls by conventional 16S rRNA sequencing and by single-cell analysis for phenotypic features by multi-parameter microbiota flow cytometry (mMFC), which complements the population-based taxonomic profiling with the characterization of individual bacterial cells.

Results: We found age to be a crucial confounder in microbiota analyses of JIA patients. Age stratification revealed specific microbiota alterations neglected by the general comparison of JIA patients and pediatric controls.

Conclusion: Age groups presented distinct taxonomic profiles and microbiota phenotypic signatures which transitioned with age, highlighting changes in the microbiota-immune system interaction with age.