Bruceine D ameliorates cholestatic liver injury by selectively modulating bile acid synthesis and activating FXR-SHP signaling.

Nuclear Receptor Ligands: Rational and Effective Therapy for Chronic Cholestatic Liver Disease?

ABC transporter regulation by bile acids: where PXR meets FXR

New treatments/targets for primary biliary cholangitis.

Efficacy and Safety of Ursodeoxycholic Acid Versus Cholestyramine in Intrahepatic Cholestasis of Pregnancy

Complementary Stimulation of Hepatobiliary Transport and Detoxification Systems by Rifampicin and Ursodeoxycholic Acid in Humans

Obeticholic acid improves hepatic bile acid excretion in patients with primary biliary cholangitis

Cerebrotendinous xanthomatosis (CTX), sterol 27-hydroxylase (CYP27A1) deficiency, is associated with markedly reduced chenodeoxycholic acid (CDCA), the most powerful activating ligand for farnesoid X receptor (FXR). We investigated the effects of reduced CDCA on FXR target genes in humans. Liver specimens from an untreated CTX patient and 10 control subjects were studied. In the patient, hepatic CDCA concentration was markedly reduced but the bile alcohol level exceeded CDCA levels in control subjects (73.5 vs. 37.8 +/- 6.2 nmol/g liver). Cholesterol 7alpha-hydroxylase (CYP7A1) and Na+/taurocholate-cotransporting polypeptide (NTCP) were upregulated 84- and 8-fold, respectively. However, small heterodimer partner (SHP) and bile salt export pump were normally expressed. Marked CYP7A1 induction with normal SHP expression was not explained by the regulation of liver X receptor alpha (LXRalpha) or pregnane X receptor. However, another nuclear receptor, hepatocyte nuclear factor 4alpha (HNF4alpha), was induced 2.9-fold in CTX, which was associated with enhanced mRNA levels of HNF4alpha target genes, CYP7A1, 7alpha-hydroxy-4-cholesten-3-one 12alpha-hydroxylase, CYP27A1, and NTCP. In conclusion, the coordinate regulation of FXR target genes was lost in CTX. The mechanism of the disruption may be explained by a normally stimulated FXR pathway attributable to markedly increased bile alcohols with activation of HNF4alpha caused by reduced bile acids in CTX liver.

We present a method using a combination of enzymatic deconjugation and targeted LC-multiple reaction monitoring (MRM)-MS analysis for analyzing all common bile acids (BAs) in piglet urine, and in particular, for detecting conjugated BAs either in the absence of their standards, or when present in low concentrations. Initially, before enzymatic deconjugation, 19 unconjugated BAs (FBAs) were detected where the total concentration of the detected FBAs was 9.90 μmol/l. Sixty-seven conjugated BAs were identified by LC-MRM-MS analysis before and after enzymatic deconjugation. Four enzymatic assays were used to deconjugate the BA conjugates. FBAs in urine after cholylglycine hydrolase/sulfatase treatment were 33.40 μmol/l, indicating the urinary BAs were comprised of 29.75% FBAs and 70.25% conjugated BAs in single and multiple conjugated forms. For the conjugates in single form, released FBAs from cholylglycine hydrolase deconjugation indicated that the conjugates with amino acids were 14.54% of urinary BAs, 16.27% glycosidic conjugates were found by β-glucuronidase treatment, and sulfatase with glucuronidase inhibitor treatment liberated FBAs that constituted 16.67% of urinary BAs. Notably, chenodeoxycholic acid (CDCA) was initially detected only in trace amounts in urine, but was found at significant levels after the enzymatic assays above. These results support that CDCA is a precursor of γ-muricholic acid in BA biosynthesis in piglets.

The pruritus of cholestasis

The aim of the study was to develop a method for fast and reliable diagnosis of peroxisomal diseases and to facilitate differential diagnosis of cholestatic hepatopathy. For the quantification of bile acids and their conjugates as well as C(27) precursors di- and trihydroxycholestanoic acid (DHCA, THCA), in small pediatric blood samples we combined HPLC separation on a reverse-phase C18 column with ESI-MS/MS analysis in the negative ion mode. Analysis was done with good precision (CV 3,7%-11.1%) and sufficient sensitivity (LOQ: 11-91 nmol/L) without derivatization. Complete analysis of 17 free and conjugated bile acids from dried blood spots and 10 microL serum samples, respectively, was performed within 12 min. Measurement of conjugated primary bile acids plus DHCA and THCA as well as ursodeoxycholic acid was done in 4.5 min. In blood spots of healthy newborns, conjugated primary bile acids were found in the range of 0.01 to 2.01 micromol/L. Concentrations of C(27) precursors were below the detection limit in normal controls. DHCA and THCA were specifically elevated in cases of peroxysomal defects and one Zellweger patient.

Obeticholic acid protects against lithocholic acid-induced exogenous cell apoptosis during cholestatic liver injury

Bile acids (BAs) are important modulators of metabolic functions such as lipid, triglyceride and glucose homeostasis. Intrahepatic accumulation of BAs is known to cause liver injury in cholestatic conditions, where normal trans-hepatic BA flow is impaired due to pathological conditions or induced by toxic drugs. Therefore, it is important to understand the mechanisms of BA homeostasis regulation and to identify novel players and characterize their functions. The main goal of the present work was to investigate the impact of altered hepatic glucocorticoid activation by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) on BA homeostasis and to unravel the mechanisms of adaptations in a scenario of impaired 11β-HSD1 function. In order to achieve this goal, we developed and validated an ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the quantification of a total of 24 BAs, including 11 unconjugated, 6 glycine-conjugated and 7 taurine-conjugated BAs, in biological matrices (serum/plasma and tissues) and cell culture supernatants. This method was validated and applied in a side project in which potential time-dependent changes of BAs in plasma from sham-operated and uninephrectomized male Sprague-Dawley rats were investigated. Several primary and secondary BAs were transiently elevated one week after uninephrectomy, followed by normalization thereafter. Using liver microsomal preparations and recombinant enzyme we then tested whether 11β-HSD1, in addition to its well-known role in the conversion of inactive to active glucocorticoids, is able to reduce 7-oxo BAs. We found that human 11β-HSD1 reduces the secondary BA 7-oxolithocholic acid (7-oxoLCA) mainly to chenodeoxycholic acid (CDCA) and to lesser amount to ursodeoxycholic acid (UDCA). 11β-HSD1 exclusively catalyzed the oxoreduction of 7-oxoLCA, in contrast to its role in the interconversion of glucocorticoids. The enzyme also metabolized 7-oxoLCA-glycine and -taurine conjugates. Furthermore, we compared 7-oxoLCA metabolism by human 11β-HSD1 with that of other species, including canine, guinea-pig, rat, mouse and hamster and we observed species-specific differences. While recombinant mouse and rat 11β-HSD1 converted 7-oxoLCA to equivalent amounts of CDCA and UDCA, the hamster and canine enzymes were stereoselective, producing mainly CDCA similar to the human enzyme. Surprisingly, guinea-pig 11β-HSD1 did not reduce 7-oxoLCA. The analysis of circulating BA profiles of several species confirmed earlier observations by other investigators, that 7-oxoLCA and its glycine-conjugated (G-7-oxoLCA) metabolite are abundant BAs in guinea-pigs compared with other species. These findings suggest that the lack of 11β-HSD1 oxoreductase activity on 7-oxoLCA in guinea-pigs is responsible for its elevated circulating levels. Next, we hypothesized that 7-oxoLCA might be a biomarker of impaired 11β-HSD1 activity. Analysis of BAs in serum from liver-specific 11β-HSD1 deficient mice revealed 18-, 47- and 7-fold elevation of 7-oxoLCA, its taurine and glycine conjugates compared with wild-type mice, respectively. In addition, 7-oxoLCA and its taurine conjugate were 2- and 6-fold elevated in liver from liver-specific 11β-HSD1 deficient mice. Moreover, BA profiles in serum and liver of liver-specific 11β-HSD1 deficient mice indicated a disturbed BA homeostasis. Circulating and intrahepatic levels of several unconjugated BAs species were up to 16-fold significantly elevated in liver-specific 11β-HSD1 deficient compared with wild-type mice. To pinpoint the molecular mechanism of altered BAs profiles, gene expression analysis was performed. The results suggest FXR-dependent decrease of BA synthesis, a compensatory effect to counteract the intrahepatic accumulation of BAs. In addition, the enzymes responsible for BA conjugation with coenzyme A, an intermediate step in BAs amidation, named VLCS and VLCSH2 displayed significantly lower expression levels in liver from liver-specific 11β-HSD1 deficient compared with wild-type mice. The decreased BA conjugating machinery in the liver of liver-specific 11β-HSD1 deficient mice may account for the elevated intrahepatic levels of unconjugated BAs observed. Moreover, the expression of OATP4, a basolateral BA transporter responsible for the uptake of unconjugated BAs from the circulation into hepatocytes presented reduced expression levels and may account for the significant elevation of several circulating unconjugated BAs found in liver-specific 11β-HSD1 deficient mice. In conclusion, we demonstrated an important role of 11β-HSD1 in the oxoreduction on 7-oxoLCA and provided evidences that 7-oxoLCA its taurine conjugate are functional biomarkers of impair 11β-HSD1 activity. Circulating concentrations of these 7-oxo BAs may find application in the assessment of the therapeutic efficacy of 11β-HSD1 inhibitors. Moreover, we described for the first time the impact of intrahepatic glucocorticoid regeneration deficiency on BA homeostasis in mice. Our findings indicate that 11β-HSD1 is an important modulator of BAs homeostasis, and potential disturbances of BA homeostasis must be taken into account when assessing the safety of 11β-HSD1 inhibitors, with particular attention to cholestatic patients and patients receiving combined therapeutic regimens with drugs known to induce liver injury.

Effect of ursodeoxycholic acid on bile acid profiles and intestinal detoxification machinery in primary biliary cirrhosis and health

Hepatic hydroxylation of bile acids and chronic liver diseases: do transporters play a mechanistic role?

Steroids in the management of PBC: Why do we need them?