The role of bile acids in the pathogenesis of bowel diseases

Abstract

Bile acids not only play a cardinal role in the digestion and absorption of fat and fat-soluble vitamins, but also significantly affect gastrointestinal motor, sensory and secretory functions, intestinal barrier permeability and the regulation of the inflammatory response. The results of recent studies have revealed complex interactions between bile acids and the gut microbiota. In addition, bile acids also play a role of signaling molecules regulating the activity of lipid and glucose metabolic pathways, as well as a role of ligands for transcription factors. Genetic factors associated with the regulation of bile acid synthesis, transport and action may significantly influence gastrointestinal function and predispose to diarrhea resulting from bile acid malabsorption. Methods used in the diagnosis of bile acid malabsorption include 75selenium-homotaurocholic acid test, serum C4 and fibroblast growth factor 19 (FGF19), as well as fecal bile acid levels. The paper presents the latest data on the role of bile acid in the pathogenesis of irritable bowel syndrome, inflammatory bowel diseases and colorectal cancer. Advances in the treatment of disturbances in bile acids absorption and synthesis are also presented. A better understanding of molecular mechanisms regulating bile acid action may have implication for colorectal cancer prevention.

Biological Clock and Inflammatory Bowel Disease Review: From the Standpoint of the Intestinal Barrier

“…Among them, various substances that make up the intestinal chemical barrier have certain functions. Lysozyme can hydrolyze peptidoglycan in bacterial cell walls to exert antibacterial effect [ 45 ], digestive enzymes can decompose macromolecular substances in food into small molecular substances for easy digestion and absorption [ 46 ], and bile acids can affect gastrointestinal motility, sensation, secretion, regulation of function, intestinal barrier permeability, and inflammatory responses [ 47 ]. In conclusion, the intestinal mucus layer plays a major role in protecting the gut from mechanical, chemical, and biological factors and contributes to the maintenance of intestinal homeostasis [ 48 ].…”

“…The first layer of mucus is approximately 50 mm, which is almost bacteria-free and able to keep the microbiota away from the epithelial barrier and limit inflammation. In the second layer of mucus, the microbiota is present and involved in its degradation, a process that is absorption [46], and bile acids can affect gastrointestinal motility, sensation, secretion, regulation of function, intestinal barrier permeability, and inflammatory responses [47].…”

Small intestinal bacterial overgrowth and nonalcoholic fatty liver disease

“…It is activated by bile acids in a different order than in the case of FXR, i.e. mainly through LCA, followed by DCA, CDCA and the worst by CA [ 33 , 34 ]. Intestinal bacteria, through the influence on the modification of the composition of bile acids, affect the activation of the above-mentioned receptors with corresponding consequences.…”

Epidural Hematoma in a Patient with Undiagnosed Vitamin K Deficiency: A Case Report

“…Common examples leading to deficiency include dietary restriction, malabsorption, major surgery, antibiotic use, and hepatic disfunction [6]. Procedures involving the terminal ileum can impair resorption of bile acids and result in depletion of the bile acid pool, impeding micelle formation and vitamin K transport into the intestinal mucosal cells [7]. Though the majority is ingested, a fraction of vitamin K is produced by bacterial species of the GI tract.…”