Ranking microbiome variance in inflammatory bowel disease: a large longitudinal intercontinental study

Area of Science:

• Microbiome research
• Gut microbiota composition
• Inflammatory Bowel Disease (IBD) pathogenesis

Background:

• The gut microbiome plays a role in inflammatory bowel disease (IBD) development.
• The influence of lifestyle and environmental factors on gut microbiota variability in IBD is not well understood.

Purpose of the Study:

• To rank the effect size of disease activity, medications, diet, and geographic location on fecal microbiota composition.
• To analyze longitudinal changes in gut microbiota in patients with Crohn's disease (CD), ulcerative colitis (UC), and controls.

Main Methods:

• 16S rRNA gene sequencing of fecal samples from 303 CD patients, 228 UC patients, and 161 controls.
• Longitudinal study design with sample collection at three time points (16-week intervals).
• Machine learning models applied to differentiate disease states and analyze microbiota variance.

Main Results:

• Reduced microbiota diversity and increased variability observed in CD and UC compared to controls.
• Significant compositional differences noted between IBD subtypes and controls.
• Geographic location was the largest contributor to microbiota variance, followed by CD diagnosis, surgery, alcohol consumption, and UC diagnosis. Medications and diet had smaller effects, with 90.3% of variance being stochastic.

Conclusions:

• Gut microbiota composition in IBD is influenced by various factors, with geographic location and disease status being prominent.
• Significant unexplained variance in microbiota composition highlights the complexity of IBD.
• Precision medicine strategies for microbiota manipulation must account for host heterogeneity, diverse lifestyles, and substantial unexplained variance.