The Role of the Gut Microbiota in Bile Acid Metabolism.

The gut microbiota has been considered a cornerstone of maintaining the health status of its human host because it not only facilitates harvesting of nutrients and energy from ingested food, but also produces numerous metabolites that can regulate host metabolism. One such class of metabolites, the bile acids, are synthesized from cholesterol in the liver and further metabolized by the gut microbiota into secondary bile acids. These bioconversions modulate the signaling properties of bile acids through the nuclear farnesoid X receptor and the G protein-coupled membrane receptor 5, which regulate diverse metabolic pathways in the host. In addition, bile acids can regulate gut microbial composition both directly and indirectly by activation of innate immune response genes in the small intestine. Therefore, host metabolism can be affected by both microbial modifications of bile acids, which leads to altered signaling via bile acid receptors, and by alterations in the composition of the microbiota. In this review, we mainly describe the interactions between bile acids and intestinal microbiota and their roles in regulating host metabolism, but we also examine the impact of bile acid composition in the gut on the intestinal microbiome and on host physiology.

Ramírez-Pérez O ，Cruz-Ramón V ，Chinchilla-López P ，Méndez-Sánchez N ... -  《Annals of Hepatology》

The Role of the Gut Microbiota in Bile Acid Metabolism.

Ramírez-Pérez O ，Cruz-Ramón V ，Chinchilla-López P ，Méndez-Sánchez N ... -  《Annals of Hepatology》

Intestinal Crosstalk between Bile Acids and Microbiota and Its Impact on Host Metabolism.

The gut microbiota is considered a metabolic "organ" that not only facilitates harvesting of nutrients and energy from the ingested food but also produces numerous metabolites that signal through their cognate receptors to regulate host metabolism. One such class of metabolites, bile acids, is produced in the liver from cholesterol and metabolized in the intestine by the gut microbiota. These bioconversions modulate the signaling properties of bile acids via the nuclear farnesoid X receptor and the G protein-coupled membrane receptor 5, which regulate numerous metabolic pathways in the host. Conversely, bile acids can modulate gut microbial composition both directly and indirectly through activation of innate immune genes in the small intestine. Thus, host metabolism can be affected through microbial modifications of bile acids, which lead to altered signaling via bile acid receptors, but also by altered microbiota composition.

Wahlström A ，Sayin SI ，Marschall HU ，Bäckhed F ... -  《-》

The gut microbiota at the intersection of bile acids and intestinal carcinogenesis: An old story, yet mesmerizing.

The prevalence of colorectal cancer (CRC) has markedly increased worldwide in the last decade. Alterations of bile acid metabolism and gut microbiota have been reported to play vital roles in intestinal carcinogenesis. About trillions of bacteria have inhabited in the human gut and maintained the balance of host metabolism. Bile acids are one of numerous metabolites that are synthesized in the liver and further metabolized by the gut microbiota, and are essential in maintaining the normal gut microbiota and lipid digestion. Multiple receptors such as FXR, GPBAR1, PXR, CAR and VDR act as sensors of bile acids have been reported. In this review, we mainly discussed interplay between bile acid metabolism and gut microbiota in intestinal carcinogenesis. We then summarized the critical role of bile acids receptors involving in CRC, and also addressed the rationale of multiple interventions for CRC management by regulating bile acids-microbiota axis such as probiotics, metformin, ursodeoxycholic acid and fecal microbiota transplantation. Thus, by targeting the bile acids-microbiota axis may provide novel therapeutic modalities in CRC prevention and treatment.

Liu T ，Song X ，Khan S ，Li Y ，Guo Z ，Li C ，Wang S ，Dong W ，Liu W ，Wang B ，Cao H ... -  《-》

Bile Acid-Activated Receptors, Intestinal Microbiota, and the Treatment of Metabolic Disorders.

The composition of the bile acid pool is a function of the microbial metabolism of bile acids in the intestine. Perturbations of the microbiota shape the bile acid pool and modulate the activity of bile acid-activated receptors (BARs) even beyond the gastrointestinal tract, triggering various metabolic axes and altering host metabolism. Bile acids, in turn, can also regulate the composition of the gut microbiome at the highest taxonomic levels. Primary bile acids from the host are preferential ligands for the farnesoid X receptor (FXR), while secondary bile acids from the microbiota are ligands for G-protein-coupled bile acid receptor 1 (GPBAR1). In this review, we examine the role of bile acid signaling in the regulation of intestinal microbiota and how changes in bile acid composition affect human metabolism. Bile acids may offer novel therapeutic modalities in inflammation, obesity, and diabetes.

Fiorucci S ，Distrutti E 《-》