Fecal microbiome of patients with ulcerative colitis reflects their phenotype and inflammatory level

Area of Science:

• Gastroenterology
• Microbiome Research
• Immunology

Background:

• Inflammatory bowel diseases (IBD), including Ulcerative Colitis (UC), affect a growing global population.
• Previous studies noted microbiome alterations in Crohn's disease and UC during relapse, but not clearly in UC remission.

Purpose of the Study:

• To characterize the gut microbiome in adult UC patients in remission compared to healthy controls.
• To investigate the relationship between microbiome composition, UC phenotype, disease activity, and quality of life.

Main Methods:

• Quantitative metagenomics was employed to analyze the gut microbiome in 121 individuals (65 UC patients in remission, 56 healthy controls).
• Cross-sectional and longitudinal analyses were performed, including Receiver-Operator Characteristic (ROC) analysis for patient classification.
• Disease activity was assessed using white blood cell count and fecal calprotectin levels.

Main Results:

• UC patients in remission exhibited significantly lower microbiome richness and a paucity of the Ruminococcus enterotype compared to controls.
• Microbiome alterations enabled robust classification of patients with an AUC of 0.87.
• Reduced richness correlated with aggressive UC phenotype, past relapses, and lower IBD quality of life (IBDQ-36).
• Conversely, increased richness was unexpectedly associated with inflammatory bouts, as indicated by elevated white blood cell count and fecal calprotectin.

Conclusions:

• Gut microbiome dysbiosis, characterized by reduced richness and specific enterotype changes, is present in UC patients even during remission.
• Microbiome composition can serve as a potential biomarker for UC classification and predicting disease course.
• A dynamic relationship exists between gut microbiome richness, inflammation markers, and clinical relapse risk in UC.