Fig 1.
Phenotypic variation among Diversity Outbred (DO) mice fed high-fat and high-sucrose diet.
(A) Abundance (peak area) of primary bile acids detected in plasma and (B) cecal contents (n = 384). (C) Distributions of the normalized relative abundance of bacterial phyla identified in DO fecal microbiota (n = 399).
Fig 2.
Genetic architecture of quantitative trait loci (QTL) for microbial exact sequence variants (ESVs) and taxa abundance, and plasma and cecal bile acids in 400 Diversity Outbred (DO) mice.
The outer layer shows the chromosome location where major tick marks correspond to 25 Mbp. Logarithm of the odds (LOD) range is shown for each track. Each dot represents a QTL on each chromosome of the mouse genome for a given trait. Grey dots denote QTLs with LOD < 6.8. Candidate genes discussed in text are denoted.
Fig 3.
Co-mapping of Turicibacter sp. and plasma cholic acid (CA) QTL on chromosome 8.
Association of (A) fecal abundance of Turicibacter sp. and (B) plasma CA levels on chromosome (chr) 8. The x-axis indicates the position in Mbp along chr 8. The y-axis for the top panel and the y-axis in the bottom panel is the LOD score. Dashed line corresponds to LOD = 6.11 (P < 0.5). A/J and WSB founder alleles are associated with higher and lower levels of Turicibacter and plasma CA levels, respectively. Estimated founder strain levels of Turicibacter sp. and plasma cholic acid were inferred in the DO population from the founder strain coefficients observed at the corresponding QTL on chr 8. The estimated founder strain abundance of (C) Turicibacter and (D) levels of plasma CA in the DO population reflects measured values observed in founder strains for (E) the abundance of Turicibacter sp. and (F) plasma cholic acid levels (n = 8 mice/genotype, 4 male and 4 female). (G) SNPs (top panel) and protein coding genes (bottom panel) under the QTL interval. Magenta dots correspond to SNPs with the strongest association where the LOD drop < 1.5 from the top SNP. (H) Relative expression of Slc10a2 measured in the distal ileum by qRT-PCR in A/J and WSB parental strains (n = 6, 3 male and 3 female). Data are presented as mean ± SEM; Welch’s t test; * p < 0.05. Correlation p-values adjusted for multiple tests using Benjamini and Hochberg correction. ND–not detected.
Fig 4.
Mediation analysis and causal inference testing suggest causal relationship between Turicibacter sp. abundance and plasma cholic acid (CA) levels.
(A) Hypothetical causal model that proposes that cholic acid (CA) mediates the changes in Turicibacter sp. abundance. (B) Change in LOD score of plasma CA when adjusting for Turicibacter sp. abundance. The x-axis indicates the position in Mbp along chr 8. (C) Hypothetical causal model that proposes that Turicibacter sp. mediates changes in abundance of plasma CA levels. (D) Change in LOD score of Turicibacter sp. when controlling for plasma CA levels. Dashed lines correspond to LOD = 6.11 (p < 0.5).
Fig 5.
Turicibacter sanguinis and bile acid interactions.
(A) Percent of conjugated bile acids detected after 24-hour incubation with or without the presence of T. sanguinis. (B) Transformation of cholic acid (CA) to 7-dehydrocholic acid (7-dHCA), and (C) chenodeoxycholic acid (CDCA) to 7-ketolithocholic acid (7-KLCA) by T. sanguinis after 24 hours. Growth of T. sanguinis in the presence of 0.1 mM, 0.5 mM, 1 mM and 5 mM (D) conjugated (equimolar pool of taurocholic acid (TCA) and glycochenodeoxycholic acid (GCDCA)), and (E) unconjugated (equimolar pool of cholic CA, CDCA, and deoxycholic acid (DCA)) bile acids over 24 hours. (F) Growth rate (μ) of T. sanguinis in medium supplemented with varying concentrations of conjugated and unconjugated bile acids. Data shown are from one experiment with three technical replicates. Data are presented as mean ± SEM; one-way ANOVA followed by Tukey’s multiple comparisons test; ** p < 0.01, *** p < 0.001, **** p < 0.0001.