Fecal microbiota composition and alterations in children diagnosed with oligoarticular juvenile idiopathic arthritis (JIA)

Juvenile idiopathic arthritis (JIA), the most prevalent childhood rheumatic disease, requires symptom onset before age 16, persistence ≥6 weeks in the same joint, and exclusion of other arthritis causes. Its multifactorial etiology likely involves genetic and environmental factors, with intestinal microbiota alterations implicated in pathogenesis. The community of microorganisms comprising bacteria, viruses, bacteriophages, fungi, and archaea is termed the microbiota. The microbiome refers to the collective genetic content of these microorganisms, along with their metabolic products and environmental interactions. The microbiota influences the risk of JIA and other inflammatory diseases through multiple mechanisms. In this study, we aimed to compare fecal microbiota composition and alterations between treatment-naïve children with oligoarticular juvenile idiopathic arthritis (JIA) and healthy controls. This prospective single-center study enrolled 25 children newly diagnosed with JIA and 25 healthy children. Intestinal microbiota composition was assessed through comprehensive metagenomic analyses. In the present study, we identified significant alterations in the intestinal microbiota composition of patients with juvenile idiopathic arthritis (JIA) compared to healthy controls. At the genus level, an increased relative abundance of Oscillibacter and Alistipes was observed in the JIA cohort, whereas Dialister and Faecalibacterium were more prevalent in the control group. Differential abundance analysis using ANCOM-BC revealed a notable enrichment of Megasphaera and Akkermansia—genera previously implicated in arthritogenic processes in the patient group. Conversely, Lactobacillus, a genus with well-documented anti-inflammatory properties, was found to be significantly reduced in JIA patients. These findings underscore the potential involvement of gut microbiota dysbiosis in the pathogenesis and progression of JIA, highlighting the need for further large-scale, longitudinal studies to elucidate underlying mechanisms and therapeutic implications.