obeticholic-acid and 7-alpha-hydroxy-4-cholesten-3-one

Bile acids (BAs) are the central signals in enterohepatic communication, and they also integrate microbiota-derived signals into enterohepatic signaling. The tissue distribution and signaling pathways activated by BAs through natural receptors, farsenoid X receptor and G protein-coupled BA receptor 1 (GPBAR1, also known as Takeda G-coupled receptor 5), have led to a greater understanding of the mechanisms and potential therapeutic agents. BA diarrhea is most commonly encountered in ileal resection or disease, in idiopathic disorders (with presentation similar to functional diarrhea or irritable bowel syndrome with diarrhea), and in association with malabsorption such as chronic pancreatitis or celiac disease. Diagnosis of BA diarrhea is based on Se-homocholic acid taurine retention, 48-hour fecal BA excretion, or serum 7αC4; the latter being a marker of hepatic BA synthesis. BA diarrhea tends to be associated with higher body mass index, increased stool weight and stool fat, and acceleration of colonic transit. Biochemical markers of increased BA synthesis or excretion are available through reference laboratories. Current treatment of BA diarrhea is based on BA sequestrants, and, in the future, it is anticipated that farsenoid X receptor agonists may also be effective. The optimal conditions for an empiric trial with BA sequestrants as a diagnostic test are still unclear. However, such therapeutic trials are widely used in clinical practice. Some national guidelines recommend definitive diagnosis of BA diarrhea over empirical trial.

Topics: Benzothiazoles; Bile Acids and Salts; Chenodeoxycholic Acid; Cholestenones; Cholestyramine Resin; Chronic Disease; Colesevelam Hydrochloride; Colestipol; Diarrhea; Diet, Fat-Restricted; Feces; Humans; Intestinal Mucosa; Irritable Bowel Syndrome; Isoxazoles; Liver; Malabsorption Syndromes; Receptors, Cytoplasmic and Nuclear; Sequestering Agents; Taurocholic Acid

The nuclear farnesoid X receptor (FXR) agonist obeticholic acid (OCA) has been developed for the treatment of liver diseases. We aimed to determine whether OCA treatment increases the risk of gallstone formation.. Twenty patients awaiting laparoscopic cholecystectomy were randomized to treatment with OCA (25 mg/day) or placebo for 3 weeks until the day before surgery. Serum bile acids (BAs), the BA synthesis marker C4 (7α-hydroxy-4-cholesten-3-one), and fibroblast growth factor 19 (FGF19) were measured before and after treatment. During surgery, biopsies from the liver and the whole bile-filled gallbladder were collected for analyses of gene expression, biliary lipids and FGF19.. In serum, OCA increased FGF19 (from 95.0 ± 8.5 to 234.4 ± 35.6 ng/L) and decreased C4 (from 31.4 ± 22.8 to 2.8 ± 4.0 nmol/L) and endogenous BAs (from 1,312.2 ± 236.2 to 517.7 ± 178.9 nmol/L; all p <0.05). At surgery, BAs in gallbladder bile were lower in patients that received OCA than in controls (OCA, 77.9 ± 53.6 mmol/L; placebo, 196.4 ± 99.3 mmol/L; p <0.01), resulting in a higher cholesterol saturation index (OCA, 2.8 ± 1.1; placebo, 1.8 ± 0.8; p <0.05). In addition, hydrophobic OCA conjugates accounted for 13.6 ± 5.0% of gallbladder BAs after OCA treatment, resulting in a higher hydrophobicity index (OCA, 0.43 ± 0.09; placebo, 0.34 ± 0.07, p <0.05). Gallbladder FGF19 levels were 3-fold higher in OCA patients than in controls (OCA, 40.3 ± 16.5 ng/L; placebo, 13.5 ± 13.1 ng/ml; p <0.005). Gene expression analysis indicated that FGF19 mainly originated from the gallbladder epithelium.. Our results show for the first time an enrichment of FGF19 in human bile after OCA treatment. In accordance with its murine homolog FGF15, FGF19 might trigger relaxation and filling of the gallbladder which, in combination with increased cholesterol saturation and BA hydrophobicity, would enhance the risk of gallstone development.. Obeticholic acid increased human gallbladder cholesterol saturation and bile acid hydrophobicity, both decreasing cholesterol solubility in bile. Together with increased hepatobiliary levels of fibroblast growth factor 19, our findings suggest that pharmacological activation of the farnesoid X receptor increases the risk of gallstone formation. Clinical trial number: NCT01625026.

Topics: Adult; Bile Acids and Salts; Biopsy; Carrier Proteins; Chenodeoxycholic Acid; Cholestenones; Double-Blind Method; Female; Fibroblast Growth Factors; Gallbladder; Gallstones; Gene Expression; Humans; Liver; Liver Diseases; Male; Middle Aged; Receptors, Cytoplasmic and Nuclear; Treatment Outcome