FMT for children with FGIDs. Fecal microbiota transplantation relieves abdominal bloating and modulates fecal microbiome and metabolome in children with functional gastrointestinal disorders

Functional gastrointestinal disorders (FGIDs) are disorders of gut-brain interaction that strongly associated with altered gut microbiota. Here, we aim to investigate the beneficial effect of fecal microbiota transplantation (FMT) for treatment of pediatric FGIDs patients with severe abdominal bloating, and to analyze the changes of gut bacterial composition and metabolites profile. A total of 12 pediatric FGIDs patients with predominate abdominal bloating underwent FMT were prospective enrolled from August 2017 to October 2020. The clinical responses were assessed at 8 weeks after FMT. 16S rRNA gene sequencing and targeted metabolomics analysis were applied to profile the fecal bacterial microbiome and metabolome, respectively. We found that abdominal bloating was relieved in all patients by FMT either via nasointestinal tube or oral capsules at 8 weeks. Meanwhile, FMT significantly improved the symptoms of abdominal pain and diarrhea after 8 weeks of intervention. The alpha diversity was significantly lower in FGIDs children, and fecal microbial community (beta diversity) was apart from HC. FGIDs children exhibited decreased relative abundances of bacterial genera Blautia, Faecalibacterium, Clostridium, and increased relative abundances of Bifidobacterium, Enterococcus and Parabacteroides. Lower concentrations of short chain fatty acids (SCFAs), and higher level of lactic acid were observed in FGIDs patients as compared with HC. The altered microbiota composition was correlated with changes of fecal metabolites profile. FMT modulated the fecal microbiome and metabolome in children with FGIDs toward a healthy state. Our findings suggest that FMT may provide an alternative therapy for FGIDs children with abdominal bloating in the future.