A Pilot Study Investigating Faecal Microbiota After Two Dietary Interventions in Children with Juvenile Idiopathic Arthritis

Abstract

There is evidence for an impact of the gut microbiota on the immune system, which has consequences for inflammatory diseases. Exclusive enteral nutrition (EEN) and the specific carbohydrate diet (SCD) have been demonstrated as effective anti-inflammatory treatments for children with Crohn's disease. We have previously shown an anti-inflammatory effect from these nutritional treatments in children with juvenile idiopathic arthritis (JIA). The aim of this study was to investigate if improved clinical symptoms after EEN or SCD treatment in children with JIA could be linked to changes in faecal microbiota. We included sixteen patients with JIA (age 7-17 years), six for treatment with EEN and ten with SCD. EEN was given for 3-5 weeks and SCD for 4-5 weeks, with clinical and laboratory status assessed before and after treatment. Faecal samples were analysed for microbiota diversity and composition using 16S rRNA gene sequencing. Analyses of the faecal microbiota showed an effect on the overall composition with both interventions; the most striking result was a decreased relative abundance of the genus Faecalibacterium from EEN and of Bifidobacterium from SCD. The α-diversity decreased significantly from SCD (P = 0.04), but not from EEN (P = 0.22). Despite the study cohorts being small, both EEN and SCD were shown to impact the faecal microbiota. Future larger studies with a focus on metagenomics or metabolomics could possibly reveal a link and clarify the clinical effects of those nutritional regimens.

Fig. 1

Flowchart of patients included in and excluded from the two studies

Fig. 2

Relative abundance of bacterial phyla in faecal samples from children with juvenile idiopathic arthritis (JIA) collected before and during diet interventions. Six children with JIA (A–F) before and during exclusive enteral nutrition (EEN), and ten children with JIA (G–P) before and during specific carbohydrate diet (SCD)

Fig. 3

Participants are not the same in a and b. The colouring of dots has been made separately for a and b. a Principal coordinates analyses of community composition of faecal microbiota in samples from children with juvenile idiopathic arthritis (JIA) before and during diet interventions with exclusive enteral nutrition (EEN). Different colours represent different study participants. Dots represent samples collected before and squares represent samples collected during the EEN intervention. b Principal coordinates analyses of community composition of faecal microbiota in samples from children with juvenile idiopathic arthritis (JIA) before and during diet interventions with specific carbohydrate diet (SCD). Different colours represent different study participants. Dots represent samples collected before and triangles represent samples collected during the SCD intervention. c Boxplots and jitter plots showing the distributions of similarity indices based on Bray–Curtis metrics. Each dot represents the similarity in microbiota composition, in each individual, between the faecal sample collected before and the faecal sample collected during the diet intervention. A high value on the y-axis represents a high similarity between the variable composition in two samples. Boxplots show the medians and interquartile ranges whereas the whiskers represent min and max values

Fig. 4

Boxplots for relative abundance of bacterial taxa at baseline, before EEN intervention and during EEN in six children with JIA. Selected taxa with a P value < 0.05 before correction for multiple analyses

Fig. 5

Boxplots for relative abundance of bacterial taxa at baseline, before SCD intervention and during SCD in ten children with JIA. Selected taxa with a P value < 0.05 before correction for multiple analyses