Title: Pharmacological Activation of PXR and CAR Downregulates Distinct Bile Acid-Metabolizing Intestinal Bacteria and Alters Bile Acid Homeostasis.
Authors: Dempsey, Joseph L; Wang, Dongfang; Siginir, Gunseli; Fei, Qiang; Raftery, Daniel; Gu, Haiwei; Yue Cui, Julia
Published In Toxicol Sci, (2019 03 01)
Abstract: The gut microbiome regulates important host metabolic pathways including xenobiotic metabolism and intermediary metabolism, such as the conversion of primary bile acids (BAs) into secondary BAs. The nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are well-known regulators for xenobiotic biotransformation in liver. However, little is known regarding the potential effects of PXR and CAR on the composition and function of the gut microbiome. To test our hypothesis that activation of PXR and CAR regulates gut microbiota and secondary BA synthesis, 9-week-old male conventional and germ-free mice were orally gavaged with corn oil, PXR agonist PCN (75 mg/kg), or CAR agonist TCPOBOP (3 mg/kg) once daily for 4 days. PCN and TCPOBOP decreased two taxa in the Bifidobacterium genus, which corresponded with decreased gene abundance of the BA-deconjugating enzyme bile salt hydrolase. In liver and small intestinal content of germ-free mice, there was a TCPOBOP-mediated increase in total, primary, and conjugated BAs corresponding with increased Cyp7a1 mRNA. Bifidobacterium, Dorea, Peptociccaceae, Anaeroplasma, and Ruminococcus positively correlated with T-UDCA in LIC, but negatively correlated with T-CDCA in serum. In conclusion, PXR and CAR activation downregulates BA-metabolizing bacteria in the intestine and modulates BA homeostasis in a gut microbiota-dependent manner.
PubMed ID: 30407581
MeSH Terms: Animals; Bacteria/classification; Bile Acids and Salts/metabolism*; Cholesterol 7-alpha-Hydroxylase/metabolism; Cytochrome P-450 Enzyme System/metabolism; Down-Regulation/drug effects; Gastrointestinal Microbiome/drug effects*; Homeostasis/drug effects; Intestine, Large/microbiology; Liver/drug effects*; Liver/metabolism; Male; Mice; Mice, Inbred C57BL; Pregnane X Receptor/metabolism*; Pregnenolone Carbonitrile/pharmacology*; Pyridines/pharmacology*; Receptors, Cytoplasmic and Nuclear/metabolism*