Genetics and Diet Shape Gut Bacteria-Bile Acid Communication Networks
Large mouse study reveals how genes and high-fat diet alter the crosstalk between gut microbes and bile acids, identifying new therapeutic targets.
Summary
Researchers studied 32 strains of mice to understand how genetics and diet influence the communication between gut bacteria and bile acids. They found that high-fat diets reduced bacterial diversity and altered bile acid metabolism in strain-specific ways. The study identified four genetic regions that control these interactions, including genes PTGR1 and PTPRD as potential therapeutic targets. This research helps explain why people respond differently to dietary changes and could lead to personalized approaches for metabolic health.
Detailed Summary
This comprehensive study investigated how genetics and diet influence the complex communication network between gut bacteria and bile acids, which plays a crucial role in metabolic health. Researchers analyzed 32 genetically diverse mouse strains (BXD population) fed either normal chow or high-fat diet for 21 weeks, examining cecal microbiome composition, bile acid levels, and colon gene expression.
The high-fat diet significantly reduced bacterial diversity across all measures (richness, evenness, Shannon index, all p<0.001) and altered microbiome composition in strain-specific ways. The ratio of Firmicutes to Bacteroidetes increased in C57BL/6J mice but decreased in DBA/2J mice on high-fat diet, with BXD strains showing variable responses based on their genetic background. Fifteen bacterial genera showed significant changes, with Lactococcus increasing most dramatically and Turicibacter nearly disappearing on high-fat diet.
Using systems genetics approaches, the team identified four diet-dependent genetic loci associated with specific gut microbiome-bile acid interactions. These included the relationship between Turicibacter sanguinis and plasma cholic acid, and Bacteroides uniformis with fecal taurolithocholic acid. By integrating human genetic databases (MiBioGen, UK Biobank, FinnGen), they prioritized PTGR1 and PTPRD as candidate genes potentially regulating these interactions.
The study demonstrates that genetic background determines how individuals respond to dietary challenges, with some mouse strains maintaining bacterial diversity despite high-fat feeding while others showed dramatic shifts. This genetic variability in microbiome-bile acid crosstalk may explain why dietary interventions work differently across populations and could inform personalized nutrition strategies for metabolic health optimization.
Key Findings
- High-fat diet reduced all measures of bacterial diversity (richness, evenness, Shannon index) with p<0.001 across 32 mouse strains
- Lactococcus abundance increased most dramatically on high-fat diet while Turicibacter nearly disappeared (15 total genera significantly changed)
- Firmicutes/Bacteroidetes ratio increased in C57BL/6J but decreased in DBA/2J mice, showing strain-specific responses to diet
- Four genetic loci were identified that control gut microbiome-bile acid interactions in a diet-dependent manner
- PTGR1 and PTPRD genes were prioritized as candidate regulators of microbiome-bile acid crosstalk using human genetic databases
- Genetic background explained significant variation in microbiome composition, with within-strain similarity greater than between-strain similarity
- Study included 295 mice across 32 strains with comprehensive multi-omics profiling over 21 weeks
Methodology
The study used 32 BXD mouse strains (295 total mice, ~5 males per strain/diet) fed chow or high-fat diet from 8-29 weeks of age. Researchers performed 16S rRNA sequencing of cecal microbiome, bile acid profiling in plasma/feces/liver, and colon transcriptome analysis. Statistical methods included PERMANOVA, ANCOM analysis, and quantitative trait locus mapping with systems genetics approaches integrating human genetic databases.
Study Limitations
The study was conducted only in male mice, limiting generalizability to females. The 21-week duration may not capture long-term effects of dietary changes. The research focused on specific bile acids and bacterial genera, potentially missing other important microbiome-metabolite interactions. Translation to humans requires validation given species differences in microbiome composition and bile acid metabolism.
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