Background/Purpose:

Oral and gut microbes have been implicated in the pathogenesis of rheumatoid arthritis, spondyloarthropathy, and juvenile enthesitis-related arthritis (ERA). Pro-inflammatory microbes in the bacteroides phyla appear to be over-represented, while commensals in the firmicutes phyla are under-represented in inflammatory disease. The role of dysbiosis in the microbiota is not well-studied in new-onset juvenile idiopathic arthritis (JIA); individual variation secondary to diet, age, and other environmental factors makes such an analysis challenging. Previous studies demonstrated that healthy children derive most of their microbes from their mothers, and thus share similar microbial communities. We hypothesized that if the gut microbiota contributes to systemic inflammation, then children with JIA will have an altered microbiota compared to their mothers.

Methods:

Stool samples were collected from ten new-onset, treatment naive JIA patients aged 2-15 years (four oligoarticular, two polyarticular, three ERA, and one psoriatic), and their mothers in preservative-filled Omnigene-GUT cryovials designed to stabilize microbial communities. DNA was extracted from stool using the PowerSoil DNA Isolation Kit, and sequencing was performed on the Illumina HiSeq-2000 platform. Human DNA sequences, duplicate reads, sequence reads with ambiguous bases, and reads shorter than 80 bases were identified and removed from analysis. Taxonomic classification and relative species abundance of bacteria were obtained using MetaPhlAn2.

Results:

Compared to their mothers, 60% of JIA patients had lower fecal firmicutes populations. In 50%, higher bacteroidetes phyla were identified. Four of ten patients had both low firmicutes and increased bacteroidetes. The mean firmicutes:bacteroides ratio in patients was 7.2 (IQR 2.8-7.8) compared to 17.5 (IQR 9.6-24.9) in their mothers. The lowest ratio was detected in oligo JIA (mean 5.1, range 2.1-7.2), followed by poly JIA (6.7, range 1.3-12) and ERA (10, range 2.8-21). Of all of the patients, the three with the lowest ratios (1.3-2.8) all carried antinuclear antibodies.

Conclusion:

Consistent with previous results in adult RA and JIA, in new-onset JIA, fecal microbial communities were skewed toward bacteroides phyla, which can be pro-inflammatory. Whether this finding reflects a microbial trigger for JIA, or rather the coincident result of immune dysregulation, remains to be determined.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/gastrointestinal-microbiota-in-new-onset-juvenile-idiopathic-arthritis/