Gut microbiota alterations in adolescent idiopathic scoliosis: a comparison study with healthy control and congenital scoliosis.

Purpose: This study aims to compare the composition of GM isolated from individuals with AIS or congenital scoliosis (CS) and age-matched control (Ctr).

Methods: A total of 48 patients with AIS, 24 patients with CS, and 31 healthy individuals were recruited as the discovery cohort, and 9 pairs of siblings where one was affected by AIS were recruited as the validation cohort. The GM profile was determined with 16S rRNA sequencing, and the alpha-diversity and beta-diversity metrics were performed with Mothur. Linear discriminant analysis (LDA) analysis was performed to identify the enriched species.

Results: The α diversity (Chao1 index) was significantly lower in AIS patients with low BMI (< 18.5) than those with normal BMI. The PcoA analysis showed a trend of clustering of GM in AIS compared to that in Ctr and CS groups (r = 0.0553, p = 0.001). METASTAT analysis showed Cellulomonadaceae was significantly enriched in AIS groups compared to CS and Ctr. LDA analysis showed 9 enriched species in AIS patients. Compared to Ctr, two species including Hungatella genus and Bacteroides fragilis were significantly enriched, while the Firmicutes versus Bacteroidetes (F/B) ratio and the Ruminococcus genus were significantly decreased in AIS but not CS groups. The significantly reduced F/B ratio and Ruminococcus genus in AIS were replicated in the validation cohort.

Conclusions: Our study elucidated an association between low BMI and GM diversity in AIS patients. The reduced F/B ratio and Ruminococcus genus in AIS patients were identified and validated in 9 pairs of AIS patients and their unaffected siblings. Our pilot results may help understand the anthropometric discrepancy in these patients and support a possible role of GM in the pathogenesis of AIS.