Gut microbiota and bile acids profiles study of ulcerative colitis and Crohn's disease patients

The global incidence of inflammatory bowel disease (IBD) is increasing, with dysbiosis of the gut microbiota identified as a significant factor contributing to chronic intestinal inflammation. This study aims to elucidate the gut microbiota and serum bile acid profiles in patients with ulcerative colitis (UC) and Crohn's disease (CD), and to explore the relationship between bacterial taxa and bile acids.

We recruited 31 UC patients, 41 CD patients, and 32 healthy controls from The First Affiliated Hospital of Zhejiang Chinese Medical University. Gut microbiota composition was analyzed by 16S rDNA sequencing of stool samples, and serum bile acid profiles were quantified using LC-MS/MS. Alpha and beta diversity were assessed, and differential abundance of bacterial genera was evaluated using non-parametric tests with false discovery rate (FDR) correction. Correlations between differentially abundant genera and bile acid levels were examined by Spearman's rank correlation.

Both UC and CD groups exhibited significant alterations in alpha and beta diversity compared to controls. At the genus level, pro-inflammatory taxa, including Escherichia-Shigella and Ruminococcus_gnavus_group, were enriched, while short-chain fatty acid (SCFA)-producing genera such as Coprococcus were depleted. Notably, SCFA-producing Romboutsia and Butyricicoccus were exclusively depleted in CD. A consistent depletion of secondary bile acids-lithocholic acid (LCA), glycolithocholic acid (GLCA), deoxycholic acid (DCA), taurodeoxycholic acid (TDCA), and glycodeoxycholic acid (GDCA)-was observed in both patient groups. Correlation analysis revealed positive associations between several Lachnospiraceae genera and DCA/LCA levels.

This study confirms gut microbiota dysbiosis and altered bile acid profiles in UC and CD, with CD displaying a more pronounced disruption of SCFA-producing bacteria. The observed depletion of Lachnospiraceae and secondary bile acids suggests a link between microbial metabolic dysfunction and IBD pathogenesis. Although Lachnospiraceae may represent a candidate for next-generation probiotic development, further mechanistic and clinical studies are required to validate its therapeutic potential.