Alterations and correlations of ileum microbiota and serum metabolites in Crohn's disease

Abstract

Background: Gut microbial imbalance is one of the recognized factors that may lead to Crohn’s disease (CD). In addition, the disturbances of gut microbiota may further contribute to metabolic disorders. The present study investigated the alterations and correlations of ileum microbiota and serum metabolites in CD.Methods: Fecal samples from the ileal stoma and venous blood samples were collected from CD patients in the active and remission stages. The composition of ileum microbiota was evaluated by 16S ribosomal RNA (rRNA) gene sequencing, and the alterations of serum metabolites including bile acids and amino acids were assessed by liquid chromatography-mass spectrometry (LC-MS).Results: The alpha diversity of ileum microbiota in the active stage was higher than in the remission stage, the statistical difference was not significant. However, a significant difference was observed for the beta diversity. On the phylum level, the relative abundances of Bacteroidetes, Desulfobacterota, Myxococcota, and Unclassified_k__norank_d__Bacteria were statistically higher in the active stage of CD. On the genus level, lower relative abundances of Veillonella, Lactococcus, Klebsiella, Unclassified_f__Enterobacteriaceae, Blautia, and Streptococcus were found in the active stage, while the contrary were observed for Bacteroides, Ralstonia, Collinsella, and Ruminococcus_torques_group with statistical differences.In terms of the alterations of serum metabolites, the concentrations of cholic acid, chenodeoxycholic acid, serine, isoleucine and arginine were higher in the active stage with statistical differences, while the concentrations of taurocholic acid, glycocholic acid, glycinechenodeoxycholic acid, asparagine, tyrosine and glycine were higher in the remission stage with statistical differences. Additionally, CDAI score was positively associated with active stage enriched microbiota and metabolites, while prealbumin was positively correlated with remission stage enriched microbiota and metabolites.Conclusion: The results revealed the dysbiosis of ileum microbiota and metabolites in CD, which varied across disease stages. Studying microbiology and metabolomics may establish a foundation for subsequent mechanistic studies and lead to novel therapy.