Genetic and Microbial Associations to Plasma and Fecal Bile Acids in Obesity Relate to Plasma Lipids and Liver Fat Content

Bile acids (BAs) are implicated in the etiology of obesity-related conditions such as non-alcoholic fatty liver disease. Differently structured BA species display variable signaling activities via farnesoid X receptor (FXR) and Takeda G protein-coupled BA receptor 1 (TGR5). This study profiles plasma and fecal BAs and plasma 7α-hydroxy-4-cholesten-3-one (C4) in 297 persons with obesity, identifies underlying genetic and microbial determinants, and establishes BA correlations with liver fat and plasma lipid parameters. We identify 27 genetic associations (p < 5 × 10−8) and 439 microbial correlations (FDR < 0.05) for 50 BA entities. Additionally, we report 111 correlations between BA and 88 lipid parameters (FDR < 0.05), mainly for C4 reflecting hepatic BA synthesis. Inter-individual variability in the plasma BA profile does not reflect hepatic BA synthetic pathways, but rather transport and metabolism within the enterohepatic circulation. Our study reveals genetic and microbial determinants of BAs in obesity and their relationship to disease-relevant lipid parameters that are important for the design of personalized therapies targeting BA-signaling pathways. [Display omitted] •Plasma bile acid profiles show large inter-individual variability in obesity•Distinct genetic and microbial associations to plasma and fecal bile acid profiles•Plasma secondary bile acids correlate with diabetes and liver fat content•Plasma C4 correlates with features of diabetic dyslipidemia in obesity Bile acids (BAs) have been implicated in obesity-related conditions such as NAFLD and hyperlipidemia. Different human BAs exert variable biological activities. Chen et al. define genetic and microbial associations to plasma and fecal BA concentrations and composition in persons with obesity and establish their relationships with liver fat and lipid phenotypes.