Characterization of serum and urinary bile acids in patients with primary biliary cirrhosis by gas-liquid chromatography-mass spectrometry: effect of ursodeoxycholic acid treatment

The changing metabolic landscape of bile acids - keys to metabolism and immune regulation

Bile acids regulate nutrient absorption and mitochondrial function, they establish and maintain gut microbial community composition and mediate inflammation, and they serve as signalling molecules that regulate appetite and energy homeostasis. The observation that there are hundreds of bile acids, especially many amidated bile acids, necessitates a revision of many of the classical descriptions of bile acids and bile acid enzyme functions. For example, bile salt hydrolases also have transferase activity. There are now hundreds of known modifications to bile acids and thousands of bile acid-associated genes, especially when including the microbiome, distributed throughout the human body (for example, there are >2,400 bile salt hydrolases alone). The fact that so much of our genetic and small-molecule repertoire, in both amount and diversity, is dedicated to bile acid function highlights the centrality of bile acids as key regulators of metabolism and immune homeostasis, which is, in large part, communicated via the gut microbiome.

Proteomic and Metabolomic Signatures of Diet Quality in Young Adults

The assessment of "omics" signatures may contribute to personalized medicine and precision nutrition. However, the existing literature is still limited in the homogeneity of participants' characteristics and in limited assessments of integrated omics layers. Our objective was to use post-prandial metabolomics and fasting proteomics to identify biological pathways and functions associated with diet quality in a population of primarily Hispanic young adults. We conducted protein and metabolite-wide association studies and functional pathway analyses to assess the relationships between a priori diet indices, Healthy Eating Index-2015 (HEI) and Dietary Approaches to Stop Hypertension (DASH) diets, and proteins (n = 346) and untargeted metabolites (n = 23,173), using data from the MetaAIR study (n = 154, 61% Hispanic). Analyses were performed for each diet quality index separately, adjusting for demographics and BMI. Five proteins (ACY1, ADH4, AGXT, GSTA1, F7) and six metabolites (undecylenic acid, betaine, hyodeoxycholic acid, stearidonic acid, iprovalicarb, pyracarbolid) were associated with both diets (p < 0.05), though none were significant after adjustment for multiple comparisons. Overlapping proteins are involved in lipid and amino acid metabolism and in hemostasis, while overlapping metabolites include amino acid derivatives, bile acids, fatty acids, and pesticides. Enriched biological pathways were involved in macronutrient metabolism, immune function, and oxidative stress. These findings in young Hispanic adults contribute to efforts to develop precision nutrition and medicine for diverse populations.

Simultaneous determination of UDCA and its major metabolites in human plasma with surrogate matrix by a rapid and specific LC-MS/MS method

A rapid, convenient, and specific liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous quantification of ursodeoxycholic acid (UDCA), and its major metabolites, glycoursodeoxycholic acid (GUDCA) and tauroursodeoxycholic acid (TUDCA) in human plasma. Methanol was chosen as surrogate matrix for preparation the calibrators to establish calibration curves. Isotope internal standard was used for each analyte. After plasma samples were deproteinized with methanol, the post-treatment samples were analyzed on a ZORBAX SB-C18 column (2.1 × 50 mm, 1.8 μm) with 2 mM ammonium acetate and acetonitrile as mobile phase at a flow rate of 0.5 mL/min. Detection was performed on a triple quadrupole mass spectrometer operating in multiple reaction monitoring (MRM) employing negative ESI interface using API5500 triple quadrupole tandem mass spectrometer system, with the transitions set at m/z 391.4 → m/z 391.4, m/z 448.3 → m/z 73.9, m/z 498.4 → m/z 80.1, m/z 395.3 → m/z 395.3, m/z 453.3 → m/z 74.0, and m/z 503.2 → m/z 79.9 for UDCA, GUDCA, TUDCA, UDCA-d4, GUDCA-d5, and TUDCA-d5, respectively. The calibration curve ranges were 5.00-2500 ng/mL for UDCA and GUDCA and 0.500-250 ng/mL for TUDCA. The intra- and inter-day precision was within 7.00% in terms of relative standard deviation (RSD%) and the accuracy within 11.75% in terms of relative error. The selectivity, sensitivity, extraction recovery, matrix effect, dilution reliability, and stability were within the acceptable range. The method was successfully applied to a pharmacokinetic study in 12 healthy Chinese volunteers after oral administration of 250 mg UDCA.

Circulating Bile Acids in Liver Failure Activate TGR5 and Induce Monocyte Dysfunction

BACKGROUND & AIMS

Retention of bile acids in the blood is a hallmark of liver failure. Recent studies have shown that increased serum bile acid levels correlate with bacterial infection and increased mortality. However, the mechanisms by which circulating bile acids influence patient outcomes still are elusive.

METHODS

Serum bile acid profiles in 33 critically ill patients with liver failure and their effects on Takeda G-protein-coupled receptor 5 (TGR5), an immunomodulatory receptor that is highly expressed in monocytes, were analyzed using tandem mass spectrometry, novel highly sensitive TGR5 bioluminescence resonance energy transfer using nanoluciferase (NanoBRET, Promega Corp, Madison, WI) technology, and in vitro assays with human monocytes.

RESULTS

Twenty-two patients (67%) had serum bile acids that led to distinct TGR5 activation. These TGR5-activating serum bile acids severely compromised monocyte function. The release of proinflammatory cytokines (eg, tumor necrosis factor α or interleukin 6) in response to bacterial challenge was reduced significantly if monocytes were incubated with TGR5-activating serum bile acids from patients with liver failure. By contrast, serum bile acids from healthy volunteers did not influence cytokine release. Monocytes that did not express TGR5 were protected from the bile acid effects. TGR5-activating serum bile acids were a risk factor for a fatal outcome in patients with liver failure, independent of disease severity.

CONCLUSIONS

Depending on their composition and quantity, serum bile acids in liver failure activate TGR5. TGR5 activation leads to monocyte dysfunction and correlates with mortality, independent of disease activity. This indicates an active role of TGR5 in liver failure. Therefore, TGR5 and bile acid metabolism might be promising targets for the treatment of immune dysfunction in liver failure.

Urinary Bile Acid Profile of Newborns Born by Cesarean Section Is Characterized by Oxidative Metabolism of Primary Bile Acids: Limited Roles of Fetal-Specific CYP3A7 in Cholate Oxidations

This work aims to investigate how the bile acid metabolism of newborns differs from that of adults along the axis of primary, secondary, and tertiary bile acids (BAs). The total unconjugated BA profiles were quantitatively determined by enzyme digestion techniques in urine of 21 newborns born by cesarean section, 29 healthy parturient women, 30 healthy males, and 28 healthy nonpregnant females. As expected, because of a lack of developed gut microbiota, newborns exhibited poor metabolism of secondary BAs. Accordingly, the tertiary BAs contributed limitedly to the urinary excretion of BAs in newborns despite their tertiary-to-secondary ratios significantly increasing. As a result, the primary BAs of newborns underwent extensive oxidative metabolism, resulting in elevated urinary levels of some fetal-specific BAs, including 3-dehydroCA, 3β,7α,12α-trihydroxy-5β-cholan-24-oic acid, 3α,12-oxo-hydroxy-5β-cholan-24-oic acid, and nine tetrahydroxy-cholan-24-oic acids (Tetra-BAs). Parturient women had significantly elevated urinary levels of tertiary BAs and fetal-specific BAs compared with female control, indicating that they may be excreted into amniotic fluid for maternal disposition. An in vitro metabolism assay in infant liver microsomes showed that four Tetra-BAs and 3-dehydroCA were hydroxylated metabolites of cholate, glycocholate, and particularly taurocholate. However, the recombinant cytochrome P450 enzyme assay found that the fetal-specific CYP3A7 did not contribute to these oxidation metabolisms as much as expected compared with CYP3A4. In conclusion, newborns show a BA metabolism pattern predominated by primary BA oxidations due to immaturity of secondary BA metabolism. Translational studies following this finding may bring new ideas and strategies for both pediatric pharmacology and diagnosis and treatment of perinatal cholestasis-associated diseases. SIGNIFICANCE STATEMENT: The prenatal BA disposition is different from adults because of a lack of gut microbiota. However, how the BA metabolism of newborns differs from that of adults along the axis of primary, secondary, and tertiary BAs remains poorly defined. This work demonstrated that the urinary BA profiles of newborns born by cesarean section are characterized by oxidative metabolism of primary BAs, in which the fetal-specific CYP3A7 plays a limited role in the downstream oxidation metabolism of cholate.

A novel immobilization fluorescence capillary analysis method and its applications

Fluorescence capillary analysis (FCA) realizes trace-level analysis of micro-volume samples; it is easy to operate, extremely low in analytical cost and can significantly lessen environmental pollution from analytical chemistry waste. FCA has the characteristics of green analytical chemistry and has been applied in clinical, biochemical, pharmaceutical, food safety and other fields. FCA basically involves a micro-volume glass capillary, a capillary holder and an ordinary fluorescence detector. The capillary is not only a container for chemical reaction and detection but also functions as a carrier to immobilize enzymes, gene probes or reagents; it can be used repeatedly or can be disposable. In analysis, the capillary which is modified with functional reagents sucks in a measured liquid for the reaction and is then inserted into the holder within the fluorescent detector for measurement. The immobilized FCA method has been successfully used in the determination of reduced coenzyme I, ethanol in liqueur, lactic acid in dairy products, pyruvic acid and glucose in serum, trace-level sulfated bile acid in urine, the ratio of pyruvic/lactic acid in serum, and pyruvic acid in cells as well as in DNA end-labeling and dyeing methods. Further, FCA can also be extended to capillary arrays to complete multipurpose simultaneous determinations and can be combined with mobile phones as fluorescence detectors for use in mobile health analytical technology. FCA will produce considerable social benefits in medicine, pharmacy, fermentation of food, environmental protection and other fields. Therefore, the relevant contents are presented in this tutorial review.

Determination of free and conjugated bile acids in serum of Apoe(-/-) mice fed different lingonberry fractions by UHPLC-MS

Bile acids (BAs) are known to be involved in cholesterol metabolism but interactions between the diet, BA profiles, gut microbiota and lipid metabolism have not been extensively explored. In the present study, primary and secondary BAs including their glycine and taurine-conjugated forms were quantified in serum of Apoe−/− mice by protein precipitation followed by reversed phase ultra-high-performance liquid chromatography and QTOF mass spectrometry. The mice were fed different lingonberry fractions (whole, insoluble and soluble) in a high-fat setting or cellulose in a high and low-fat setting. Serum concentrations of BAs in mice fed cellulose were higher with the high-fat diet compared to the low-fat diet (20–70%). Among the lingonberry diets, the diet containing whole lingonberries had the highest concentration of chenodeoxycholic acid (CDCA), ursodeoxycholic acid (UDCA), tauro-ursodeoxycholic acid (T-UDCA), α and ω-muricholic acids (MCA) and tauro-α-MCA (T-α-MCA), and the lowest concentration of tauro-cholic acid (T-CA), deoxycholic acid (DCA) and tauro-deoxycholic acid (T-DCA). The glycine-conjugated BAs were very similar with all diets. CDCA, UDCA and α-MCA correlated positively with Bifidobacterium and Prevotella, and T-UDCA, T-α-MCA and ω-MCA with Bacteroides and Parabacteroides.

Neonatal sepsis leads to early rise of rare serum bile acid tauro-omega-muricholic acid (TOMCA)

BACKGROUND

We investigated 'rare' bile acids (BA) as potential markers in septic neonates.

METHODS

'Rare' (C-6 hydroxylated BA) and 'classical' BA were determined in 102 neonates using high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS). Four groups according to maturity (full term, FT vs. preterm, PT) and septic status (early-onset neonatal sepsis, EOS vs. CTR; non-septic controls) were formed: FT-CTR; (n = 47), PT-CTR (n = 22), FT-EOS (n = 20), PT-EOS (n = 13).

RESULTS

Firstly, FT-CTR had a significant higher amount of 'rare' BA than PT (FT-CTR: 0.5 µmol/L, IQR: 0.3-1.3 vs. PT-CTR: 0.01 µmol/L, IQR 0.01-0.2; p < 0.01). The most common 'rare' BA in FT-CTR were tauro-γ- (TGMCA) and tauro-α-muricholic acid (TAMCA). Secondly, in EOS, absolute 'rare' BA levels were comparable in both gestational age groups (FT-EOS: 0.6 µmol/L, IQR: 0.1-1.6 and PT-EOS: 0.6 µmol/L, IQR: 0.2-1.5). Therefore, EOS had significantly higher median 'rare' BA values than non-septic PT neonates (p < 0.01). In PT and term neonates, the relative amount of tauro-ω-muricholic acid (TOMCA) within the 'rare' BA pool was significantly higher in EOS than in controls (FT-CTR vs. "FT-EOS and PT-CTR vs. PT-EOS; p < 0.01). It was hence the predominant 'rare' BA in EOS.

CONCLUSION

TOMCA is an independent factor associated with EOS. It has diagnostic potential.

Rapid analysis of bile acids in different biological matrices using LC-ESI-MS/MS for the investigation of bile acid transformation by mammalian gut bacteria

Bile acids are important signaling molecules that regulate cholesterol, glucose, and energy homoeostasis and have thus been implicated in the development of metabolic disorders. Their bioavailability is strongly modulated by the gut microbiota, which contributes to generation of complex individual-specific bile acid profiles. Hence, it is important to have accurate methods at hand for precise measurement of these important metabolites. Here, a rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous identification and quantitation of primary and secondary bile acids as well as their taurine and glycine conjugates was developed and validated. Applicability of the method was demonstrated for mammalian tissues, biofluids, and cell culture media. The analytical approach mainly consists of a simple and rapid liquid-liquid extraction procedure in presence of deuterium-labeled internal standards. Baseline separation of all isobaric bile acid species was achieved and a linear correlation over a broad concentration range was observed. The method showed acceptable accuracy and precision on intra-day (1.42-11.07 %) and inter-day (2.11-12.71 %) analyses and achieved good recovery rates for representative analytes (83.7-107.1 %). As a proof of concept, the analytical method was applied to mouse tissues and biofluids, but especially to samples from in vitro fermentations with gut bacteria of the family Coriobacteriaceae. The developed method revealed that the species Eggerthella lenta and Collinsella aerofaciens possess bile salt hydrolase activity, and for the first time that the species Enterorhabdus mucosicola is able to deconjugate and dehydrogenate primary bile acids in vitro.

[Ursodeoxycholic acid: A therapeutic niche in an internist's practice]

The paper shows more than 40 years' experience with ursodeoxycholic acid (UDCA) used as a drug; during this period it has demonstrated its rather high clinical efficacy. Due to the range of its inherent pleiotropic (choleretic, cytoprotective, immunomodulatory, antiapoptotic, hypocholesterolemic, and litholytic) properties, UDCA has a broad spectrum of therapeutic activity. The paper considers the issues associated with the mechanism of action and with the clinical effects of this bile acid. It gives the results of the most important randomized controlled trials determining currently the evidence base for the efficiency and safety of using UDCA in the clinical picture of visceral diseases.

A metabonomic study of adjuvant-induced arthritis in rats using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Rheumatoid arthritis (RA) is a chronic systemic inflammatory and autoimmune disease accompanied by the destruction and deformities of joints. Adjuvant-induced arthritis (AIA) is one of the excellent animal models of RA used to understand disease pathogenesis and screen potential drugs. In this paper, a urinary metabonomics method based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) has been established to investigate the disease progression of AIA and find potential biomarkers of secondary inflammation in AIA rats. 24 potential biomarkers were identified, including xanthurenic acid, kynurenic acid, 4-pyridoxic acid, and phenylalanine, which revealed that tryptophan metabolism, phenylalanine metabolism, gut microbiota metabolism and energy metabolism were disturbed in AIA rats. These potential biomarkers and their corresponding pathways are helpful to further understand the mechanisms of AIA and pathogenesis of RA. This study demonstrates that metabonomics based on UPLC-Q-TOF-MS is a powerful methodology to analyze the underlying disease pathogenesis.

Nontargeted modification-specific metabolomics study based on liquid chromatography-high-resolution mass spectrometry

Modifications of genes and proteins have been extensively studied in systems biology using comprehensive analytical strategies. Although metabolites are frequently modified, these modifications have not been studied using -omics approaches. Here a general strategy for the nontargeted profiling of modified metabolites, which we call "nontargeted modification-specific metabolomics", is reported. A key aspect of this strategy was the combination of in-source collision-induced dissociation liquid chromatography-mass spectrometry (LC-MS) and global nontargeted LC-MS-based metabolomics. Characteristic neutral loss fragments that are specific for acetylation, sulfation, glucuronidation, glucosidation, or ribose conjugation were reproducibly detected using human urine as a model specimen for method development. The practical application of this method was demonstrated by profiling urine samples from liver cirrhosis patients. Approximately 900 features were identified as modified endogenous metabolites and xenobiotics. Moreover, this strategy supports the identification of compounds not included in traditional metabolomics databases (HMDB, Metlin, and KEGG), which are currently referred to as "unknowns" in metabolomics projects. Nontargeted modification-specific metabolomics opens a new perspective in systems biology.

Ursodeoxycholic acid for primary biliary cirrhosis

BACKGROUND

Ursodeoxycholic acid is administered to patients with primary biliary cirrhosis, a chronic progressive inflammatory autoimmune-mediated liver disease with unknown aetiology. Despite its controversial effects, the U.S. Food and Drug Administration has approved its usage for primary biliary cirrhosis.

OBJECTIVES

To assess the beneficial and harmful effects of ursodeoxycholic acid in patients with primary biliary cirrhosis.

SEARCH METHODS

We searched for eligible randomised trials in The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, LILACS, Clinicaltrials.gov, and the WHO International Clinical Trials Registry Platform. The literature search was performed until January 2012.

SELECTION CRITERIA

Randomised clinical trials assessing the beneficial and harmful effects of ursodeoxycholic acid versus placebo or 'no intervention' in patients with primary biliary cirrhosis.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data. Continuous data were analysed using mean difference (MD) and standardised mean difference (SMD). Dichotomous data were analysed using risk ratio (RR). Meta-analyses were conducted using both a random-effects model and a fixed-effect model, with 95% confidence intervals (CI). Random-effects model meta-regression was used to assess the effects of covariates across the trials. Trial sequential analysis was used to assess risk of random errors (play of chance). Risks of bias (systematic error) in the included trials were assessed according to Cochrane methodology bias domains.

MAIN RESULTS

Sixteen randomised clinical trials with 1447 patients with primary biliary cirrhosis were included. One trial had low risk of bias, and the remaining fifteen had high risk of bias. Fourteen trials compared ursodeoxycholic acid with placebo and two trials compared ursodeoxycholic acid with 'no intervention'. The percentage of patients with advanced primary biliary cirrhosis at baseline varied from 15% to 83%, with a median of 51%. The duration of the trials varied from 3 to 92 months, with a median of 24 months. The results showed no significant difference in effect between ursodeoxycholic acid and placebo or 'no intervention' on all-cause mortality (45/699 (6.4%) versus 46/692 (6.6%); RR 0.97, 95% CI 0.67 to 1.42, I² = 0%; 14 trials); on all-cause mortality or liver transplantation (86/713 (12.1%) versus 89/706 (12.6%); RR 0.96, 95% CI 0.74 to 1.25, I² = 15%; 15 trials); on serious adverse events (94/695 (13.5%) versus 107/687 (15.6%); RR 0.87, 95% CI 0.68 to 1.12, I² = 23%; 14 trials); or on non-serious adverse events (27/643 (4.2%) versus 18/634 (2.8%); RR 1.46, 95% CI 0.83 to 2.56, I² = 0%; 12 trials). The random-effects model meta-regression showed that the risk of bias of the trials, disease severity of patients at entry, ursodeoxycholic acid dosage, and trial duration were not significantly associated with the intervention effects on all-cause mortality, or on all-cause mortality or liver transplantation. Ursodeoxycholic acid did not influence the number of patients with pruritus (168/321 (52.3%) versus 166/309 (53.7%); RR 0.96, 95% CI 0.84 to 1.09, I² = 0%; 6 trials) or with fatigue (170/252 (64.9%) versus 174/244 (71.3%); RR 0.90, 95% CI 0.81 to 1.00, I² = 62%; 4 trials). Two trials reported the number of patients with jaundice and showed a significant effect of ursodeoxycholic acid versus placebo or no intervention in a fixed-effect meta-analysis (5/99 (5.1%) versus 15/99 (15.2%); RR 0.35, 95% CI 0.14 to 0.90, I² = 51%; 2 trials). The result was not supported by the random-effects meta-analysis (RR 0.56, 95% CI 0.06 to 4.95). Portal pressure, varices, bleeding varices, ascites, and hepatic encephalopathy were not significantly affected by ursodeoxycholic acid. Ursodeoxycholic acid significantly decreased serum bilirubin concentration (MD -8.69 µmol/l, 95% CI -13.90 to -3.48, I² = 0%; 881 patients; 9 trials) and activity of serum alkaline phosphatases (MD -257.09 U/L, 95% CI -306.25 to -207.92, I² = 0%; 754 patients, 9 trials) compared with placebo or no intervention. These results were supported by trial sequential analysis. Ursodeoxycholic acid also seemed to improve serum levels of gamma-glutamyltransferase, aminotransferases, total cholesterol, and plasma immunoglobulin M concentration. Ursodeoxycholic acid seemed to have a beneficial effect on worsening of histological stage (random; 66/281 (23.5%) versus 103/270 (38.2%); RR 0.62, 95% CI 0.44 to 0.88, I² = 35%; 7 trials).

AUTHORS' CONCLUSIONS

This systematic review did not demonstrate any significant benefits of ursodeoxycholic acid on all-cause mortality, all-cause mortality or liver transplantation, pruritus, or fatigue in patients with primary biliary cirrhosis. Ursodeoxycholic acid seemed to have a beneficial effect on liver biochemistry measures and on histological progression compared with the control group. All but one of the included trials had high risk of bias, and there are risks of outcome reporting bias and risks of random errors as well. Randomised trials with low risk of bias and low risks of random errors examining the effects of ursodeoxycholic acid for primary biliary cirrhosis are needed.

Targeted profiling of circulating and hepatic bile acids in human, mouse, and rat using a UPLC-MRM-MS-validated method

Bile acids (BAs) are a group of chemically related steroids recognized as regulatory molecules whose profiles can change in different physio-pathological situations. We have developed a sensitive, fast, and reproducible ultraperformance liquid chromatography/multiple reaction monitoring/mass spectrometry method to determine the tissue and sera BA profiles in different species (human, rat, and mouse) by quantifying 31 major and minor BA species in a single 21-min run. The method has been validated according to FDA guidelines, and it generally provides good results in terms of intra- and interday precision (less than 8.6% and 16.0%, respectively), accuracy (relative error measurement between -11.9% and 8.6%), and linearity (R(2) > 0.996 and dynamic ranges between two and four orders of magnitude), with limits of quantification between 2.5 and 20 nM. The new analytical approach was applied to determine BA concentrations in human, rat, and mouse serum and in liver tissue. Our comparative study confirmed and extended previous reports, showing marked interspecies differences in circulating and hepatic BA composition. The targeted analysis revealed the presence of unexpected minoritary BAs, such as tauro-alpha-Muricholic acid in human serum, thus allowing us to obtain a thorough profiling of human samples. Its great sensitivity, low sample requirements (25 µl of serum, 5 mg of tissue), and comprehensive capacity to profile a considerable number of BAs make the present method a good choice to study BA metabolism in physiological and pathological situations, particularly in toxicological studies.

Ingenuity pathways analysis of urine metabonomics phenotypes toxicity of gentamicin in multiple organs

We introduce the use of Ingenuity Pathway Analysis to analyzing global metabonomics in order to characterize phenotypically biochemical perturbations and the potential mechanisms of the gentamicin-induced toxicity in multiple organs. A single dose of gentamicin was administered to Sprague Dawley rats (200 mg/kg, n = 6) and urine samples were collected at -24-0 h pre-dosage, 0-24, 24-48, 48-72 and 72-96 h post-dosage of gentamicin. The urine metabonomics analysis was performed by UPLC/MS, and the mass spectra signals of the detected metabolites were systematically deconvoluted and analyzed by pattern recognition analyses (Heatmap, PCA and PLS-DA), revealing a time-dependency of the biochemical perturbations induced by gentamicin toxicity. As result, the holistic metabolome change induced by gentamicin toxicity in the animal's organisms was characterized. Several metabolites involved in amino acid metabolism were identified in urine, and it was confirmed that gentamicin biochemical perturbations can be foreseen from these biomarkers. Notoriously, it was found that gentamicin induced toxicity in multiple organs system in the laboratory rats. The proof-of-knowledge based Ingenuity Pathway Analysis revealed gentamicin induced liver and heart toxicity, along with the previously known toxicity in kidney. The metabolites creatine, nicotinic acid, prostaglandin E2, and cholic acid were identified and validated as phenotypic biomarkers of gentamicin induced toxicity. Altogether, the significance of the use of metabonomics analyses in the assessment of drug toxicity is highlighted once more; furthermore, this work demonstrated the powerful predictive potential of the Ingenuity Pathway Analysis to study of drug toxicity and its valuable complementation for metabonomics based assessment of the drug toxicity.

Efficacy of urine bile acid as a non-invasive indicator of liver damage in rats

Estimation of liver damage is important in the pathophysiological and toxicological study of liver disease. As a novel, non-invasive marker of liver damage, we studied the efficacy of urine bile acids (UBA) in a rat model of liver disease. Thioacetamide (TAA)-treated rats were used in this study. Single intraperitoneal administration of high-dose TAA induces severe damage to the liver, and thus is used as a model of acute hepatitis. Continuous administration of low-dose TAA yields mild damage to the liver, and induces cirrhosis and hepatic tumors. In this study, it was found that both acute and chronic administration of TAA was associated with a dose-dependent elevation of UBA. The elevation of UBA content correlated with the alteration of blood biochemical indicators, and UBA screening showed a remarkable ability to distinguish liver-damaged rats from healthy rats. In particular, UBA analysis was found to have high sensitivity, specificity, and positive predictive value for the screening of rats with abnormal serum alkaline phosphatase (ALP) activity due to chronic liver damage, which was confirmed to include cholestasis and subsequent cirrhosis by liver histological analysis. In conclusion, we demonstrated that measurement of UBA is a simple, non-invasive and effective method for the screening of cholestasis in TAA-treated rats. We suggest that UBA analysis may have potent applicability for monitoring the progress of liver damage in animal models of chronic liver disease, such as cirrhosis and hepatic encephalopathy.

Ursodeoxycholic acid for primary biliary cirrhosis

BACKGROUND

Primary biliary cirrhosis is an uncommon autoimmune liver disease with unknown aetiology. Ursodeoxycholic acid (UDCA) has been used for primary biliary cirrhosis, but the effects remain controversial.

OBJECTIVES

To evaluate the benefits and harms of UDCA on patients with primary biliary cirrhosis against placebo or no intervention.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Central Register of Controlled Trials on The Cochrane Library, MEDLINE, EMBASE, SCI-EXPANDED, The Chinese Biomedical CD Database, LILACS, and the references of identified studies. The last search was performed in January 2007.

SELECTION CRITERIA

Randomised clinical trials evaluating UDCA versus placebo or no intervention in patients with primary biliary cirrhosis.

DATA COLLECTION AND ANALYSIS

The primary outcomes were mortality and mortality or liver transplantation. Binary outcomes were reported as odds ratio (OR) or relative risk (RR) and continuous outcomes as weighted mean difference, all with 95% confidence intervals (CI). Meta-regression was used to investigate the associations between UDCA effects and quality of the trial, UDCA dose, trial duration, and patient's severity of primary biliary cirrhosis. We also used Bayesian meta-analytic approach to estimate the UDCA effect as sensitivity analysis.

MAIN RESULTS

Sixteen randomised clinical trials evaluating UDCA against placebo or no intervention were identified. Data from three trials have been updated. Nearly half of the trials had high risk of bias. The combined results demonstrated no significant effects favouring UDCA on mortality (OR 0.97, 95% CI 0.67 to 1.42) and mortality or liver transplantation (RR 0.92, 95% CI 0.71 to 1.21). The findings were supported by the Bayesian meta-analyses. UDCA did not improve pruritus, fatigue, autoimmune conditions, liver histology, or portal pressure. UDCA seemed to improve biochemical variables, like serum bilirubin, ascites, and jaundice, but the findings were based on few trials with sparse data. The use of UDCA is significantly associated with adverse events, mainly weight gain.

AUTHORS' CONCLUSIONS

This systematic review did not demonstrate any benefit of UDCA on mortality and mortality or liver transplantation of patients with primary biliary cirrhosis. The few beneficial effects could not be due to random errors or outcome reporting bias.

High-dose ursodeoxycholic acid for the treatment of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a cholestatic liver disease that results in progressive fibrosis of intrahepatic and extrahepatic bile ducts. No effective therapy currently exists for this disease. Ursodeoxycholic acid (UDCA), a hydrophilic bile acid, is the most promising treatment option because of its benign side effect profile and documented benefit in the treatment of other cholestatic liver diseases, including primary biliary cirrhosis. Multiple studies using standard-dosage (8-15 mg/kg/d) and high-dosage (20-30 mg/kg/d) UDCA generally show improvement in liver chemistries in PSC patients, and several show improvement in liver histology. However, the majority of trials using UDCA in PSC are underpowered and fail to show improvements in clinically relevant endpoints, such as delayed progression to cirrhosis, portal hypertension, liver transplantation, development of cholangiocarcinoma, or death.

Adaptive response to increased bile acids: induction of MDR1 gene expression and P-glycoprotein activity in renal epithelial cells

Cholestatic liver disease and increased serum bile acid concentrations are known to trigger various adaptive responses including the induction of hepatic, intestinal and renal bile acid transport proteins, but renal P-glycoprotein (Pgp, multidrug resistance protein 1, MDR1) remained uninvestigated in this context. We show that treatment of Madin Darby canine kidney (MDCK) cells with pathophysiologically relevant concentrations of chenodeoxycholic acid (CDCA; 100 microM) for 12 h induces MDR1 transcript levels in vitro more than twofold. CDCA and deoxycholic acid pre-treatment for 24-96 h (100 microM) also increased Pgp activity measured as rhodamine efflux, while cholic acid and taurocholic acid were not effective in concentrations up to 600 microM. CDCA pre-treatment (100 microM, 72 h) also resulted in a doubling of rhodamine123 secretion across an epithelium-like monolayer grown on Transwell filters and decreased the sensitivity towards the kidney toxic drugs cyclosporine A and paclitaxel. These findings predict physiologically as well as pharmacologically relevant consequences of liver disease for Pgp substrate transport and toxicity in the kidneys.

Chenodeoxycholic acid and taurochenodexycholic acid induce anti-apoptotic cIAP-1 expression in human hepatocytes

BACKGROUND AND AIMS

Increased concentration of endogenous bile acids in the liver correlates with clinical features of cholestatic liver diseases. Recently, it was reported that non-toxic hydrophobic bile acid activated a survival signaling pathway via phosphatidylinositol 3 (PI3) kinase in hepatocytes. However, whether bile acid induces inhibitors of apoptosis protein (IAPs) directly in human hepatocytes remains unknown. This study investigated effects of bile acids on cIAP-1, cIAP-2 and XIAP expression in hepatocytes.

METHODS

Human fetal hepatocytes and HepG2 cells were treated with free or conjugated chenodeoxycholic acid (CDCA) or ursodeoxycholic acid in the presence or absence of several inhibitors. Reverse transcriptase-polymerase chain reaction and Western blot analyses were performed for mRNA and protein expressions, respectively, of IAPs. Luciferase assay was used to investigate transcriptional activity of nuclear factor (NF)-kappaB.

RESULTS

Chenodeoxycholic acid up-regulated both mRNA and protein expressions of cIAP-1. In particular, taurochenodeoxycholic acid (TCDCA), but not glycochenodeoxycholic acid (GCDCA), induced cIAP-1 mRNA expression. In contrast, cIAP-2 and XIAP mRNA expressions were not influenced by CDCA. Moreover, CDCA-induced cIAP-1 mRNA expression was inhibited completely by calphostin C and SB203580, but not by wortmannin. Luciferase assay showed that CDCA and TCDCA activated NF-kappaB-driven transcriptional activity.

CONCLUSION

It was shown that CDCA induced cIAP-1 expression in hepatocytes through protein kinase C- and p38 mitogen-activated protein kinase-mediated pathway. Especially, TCDCA, but not GCDCA, increased cIAP-1 mRNA expression and NF-kappaB-regulated transcriptional activity. Therefore, it is suggested that CDCA and TCDCA themselves have an inhibitory potential against apoptosis through the cIAP-1-survival signaling pathway, in addition to PI3 kinase-dependent pathway.

Ursodeoxycholic acid inhibits translocation of protein kinase C in human colonic cancer cell lines

Deoxycholic acid (DCA) has been implicated in colonic carcinogenesis through effects mediated by protein kinase C (PKC) activation. By contrast, ursodeoxycholic acid (UDCA) is reported to reduce colon cancer incidence in ulcerative colitis. The aim of this study was to investigate whether UDCA modulated DCA-induced PKC isoenzyme translocation to its site of activity. HCT116 cells were treated with DCA, UDCA alone or pre-treated with UDCA followed by DCA. Analysis of translocation of endogenous and enhanced green fluorescent protein (EGFP) constructs of PKC isoenzymes was performed. Both DCA and phorbol myristate acetate (PMA) but not UDCA caused translocation of endogenous PKC alpha, epsilon and delta and transfected PKC beta1-, epsilon- and delta-EGFP from cytosol to plasma membrane, reflecting isoenzyme activation. Furthermore, UDCA inhibited DCA-induced translocation of PKC isoenzymes. Inhibition of DCA-induced PKC translocation may be a mechanism for UDCA-mediated chemoprevention of colon carcinogenesis.

Novel pathways of bile acid metabolism involving CYP3A4

The hepatic predominating cytochrome P450, CYP3A4, plays an essential role in the detoxification of bile acids and is important in pathological conditions such as cholestasis where CYP3A4 is adaptively up-regulated. However, the mechanism that triggers the up-regulation of CYP3A4 is still not clear. In this study, using recombinant CYP3A4 and human liver microsomes, we demonstrate that CYP3A4 can metabolise lithocholic acid into 3-dehydrolithocholic acid, a potent activator of the nuclear receptors, pregnane X receptor and 1,25-dihydroxy vitamin D3 receptor, which are known to regulate the expression of CYP3A4. This process thus provides a feed-forward metabolism of toxic bile acid that may be of importance in maintaining bile acid homeostasis. We also provide evidence for a novel CYP3A4-mediated metabolic pathway of the secondary bile acid deoxycholic acid. Patients treated with the antiepileptic drug carbamazepine, a CYP3A4 inducer, had markedly elevated urinary excretion of 1beta-hydroxydeoxycholic acid compared to healthy controls. The importance of CYP3A4 in this process was verified by incubations with recombinant CYP3A4 and human liver microsomes, both of which efficiently converted deoxycholic acid into 1beta-hydroxydeoxycholic acid. Interestingly, CYP3A4 was also found to be active against the secondary bile acid ursodeoxycholic acid.

Hydrophilic 7 beta-hydroxy bile acids, lovastatin, and cholestyramine are ineffective in the treatment of cerebrotendinous xanthomatosis

We compared the effect of treatments with hydrophilic bile acids (ursodeoxycholic and ursocholic acids), cholestyramine, and lovastatin versus chenodeoxycholic acid in 4 patients with cerebrotendinous xanthomatosis (CTX). Bile acids and bile alcohols in plasma, bile, and urine before and after treatment were quantitated by gas-liquid chromatography. Untreated, all patients showed abnormal biliary bile acid composition: cholic acid (72.7%) and chenodeoxycholic acid (6.2%), and polyhydroxylated C(27)-bile alcohols (10.0%), and elevated plasma cholestanol levels. Treatment with hydrophobic chenodeoxycholic acid inhibited abnormal bile acid synthesis (virtual disappearance of C(27)-bile alcohols from plasma, bile, and urine and marked reduction of plasma cholestanol levels). Hydrophilic ursodeoxycholic and ursocholic acids did not inhibit abnormal bile acid synthesis, while cholestyramine increased abnormal bile acid synthesis (continued increased formation of polyhydroxylated C(27)-bile alcohols and further elevation of plasma cholestanol levels). Lovastatin did not affect abnormal bile acid synthesis or reduce plasma cholestanol levels. The results demonstrate that impaired side-chain oxidation in bile acid synthesis due to mutations of Cyp27 results in increased formation of polyhydroxylated C(27)-bile alcohols and cholestanol in CTX. Hydrophobic chenodeoxycholic acid, but not cholestyramine, lovastatin, or hydrophilic 7beta-hydroxy acids, inhibited the abnormal synthetic pathway. The role of chenodeoxycholic acid in downregulating abnormal bile acid synthesis in CTX is emphasized.

High-performance liquid chromatographic mass spectrometric method for the determination of ursodeoxycholic acid and its glycine and taurine conjugates in human plasma

A novel sensitive high-performance liquid chromatography-electrospray mass spectrometry method has been developed for the determination of ursodeoxycholic acid (UDCA) and its glycine and taurine conjugates, glycoursodeoxycholic acid (GDCA) and tauroursodeoxycholic acid (TDCA). The procedure involved a solid phase extraction of UDCA, GDCA, TDCA and the internal standard, 23-nordeoxycholic acid from human plasma on a C18 Bond Elut cartridge. Chromatography was performed by isocratic reverse phase separation with methanol/25 mM ammonium acetate (40/60, v/v) containing 0.05% acetic acid on a C18 column with embedded polar functional group. Detection was achieved using an LC-MS/MS system. The standard curve was linear over a working range of 10-3000 ng/ml for all analytes and gave an average correlation coefficient of 0.9992 or better during validation. The absolute recovery for UDCA, GDCA, TDCA and the internal standard was 87.3, 83.7, 79.5 and 95.8%, respectively. This method is simple, sensitive and suitable for pharmacokinetics, bioequivalence or clinical studies.

Systematic review: ursodeoxycholic acid--adverse effects and drug interactions

BACKGROUND

Ursodeoxycholic acid is increasingly being used for the treatment of chronic cholestatic liver diseases. It appears to be generally well tolerated, but a systematic review on drug safety is lacking.

AIM

As experimental data suggest a role of bile acids in the regulation of hepatic drug metabolism at both the transcriptional and post-transcriptional level, the literature was screened for adverse drug reactions and drug interactions related to ursodeoxycholic acid.

METHODS

A systematic review of the literature was performed using a refined search strategy to evaluate the adverse effects of ursodeoxycholic acid and its interactions with other drugs.

RESULTS

Ursodeoxycholic acid caused diarrhoea in a small proportion of patients. Rare skin reactions were due to drug adjuvants rather than the active substance. Decompensation of liver cirrhosis was reported after the administration of ursodeoxycholic acid in single cases of end-stage primary biliary cirrhosis. Recurrent right upper quadrant abdominal pain was incidentally observed. The absorption of ursodeoxycholic acid was impaired by colestyramine, colestimide, colestipol, aluminium hydroxide and smectite. Metabolic drug interactions were reported for the cytochrome P4503A substrates, ciclosporin, nitrendipine and dapsone.

CONCLUSIONS

Ursodeoxycholic acid is generally well tolerated. Drug absorption interactions with anion exchange resins deserve consideration. Metabolic interactions with compounds metabolized by cytochrome P4503A are to be expected.

Adaptive changes in hepatobiliary transporter expression in primary biliary cirrhosis

BACKGROUND/AIMS

Information about alterations of hepatobiliary transporter expression in primary biliary cirrhosis (PBC) could provide important insights into the pathogenesis of cholestasis. This study aimed to determine the expression of hepatobiliary transport systems for bile salts (Na(+)/taurocholate cotransporter, NTCP; bile salt export pump, BSEP), organic anions (organic anion transporting protein, OATP2; canalicular conjugate export pump, MRP2; basolateral MRP homologue, MRP3), organic cations (canalicular multidrug export pump, MDR1), and phospholipids (canalicular phospholipid flippase MDR3) in livers from patients with advanced stages of PBC.

METHODS

Transporter mRNA and protein levels were assessed by reverse transcription polymerase chain reaction and Western blot analysis. Tissue distribution of transporters was investigated by immunohistochemistry and immunofluorescence microscopy. Hepatic bile acids were measured by gas chromatography-mass spectrometry.

RESULTS

Compared to controls, basolateral uptake systems (NTCP, OATP2) were reduced, canalicular export pumps for bile salts and bilirubin (BSEP, MRP2) were preserved, while canalicular MDR P-glycoproteins (MDR1, MDR3) and the basolateral efflux pump MRP3 were increased in PBC. Double immunofluorescence labeling with a canalicular marker (dipeptidyl peptidase IV) demonstrated proper canalicular localization of BSEP and MRP2 in PBC. OATP2 and MRP2 expression correlated inversely with hepatic levels of hydrophobic bile acids, while positively correlating with hepatic enrichment with ursodeoxycholic acid.

CONCLUSIONS

Down-regulation of basolateral uptake systems and maintenance/up-regulation of canalicular and basolateral efflux pumps may represent adaptive mechanisms limiting the accumulation of toxic biliary constituents.

Simultaneous quantitation of fatty acids, sterols and bile acids in human stool by capillary gas-liquid chromatography

A simple method for the simultaneous gas-liquid chromatographic quantitation of fatty acids, sterols and bile acids from human fecal samples is described. The various compounds are directly converted into the n-butyl ester-trimethylsilyl ether derivatives, without prior isolation from the stool. Under these conditions, fecal bile acid derivatives are well resolved from each other and from those of fecal fatty acids and sterols without overlaps. The method was found to be reproducible and recoveries were similar to those obtained after exhaustive solvent extraction of fecal sterols, fatty acids and bile acids. Optimum derivatization conditions that allowed maximum recovery of fecal components with minimal destruction and application of the method for simultaneous bile acid, fatty acid and sterol analysis in human stool are described.

Serum bile acids in patients with liver failure supported with a bioartificial liver

BACKGROUND

Serum bile acids are increased in liver failure, but the composition of the bile acid pool in this condition has not been studied in detail. This information is of interest because of dihydroxy bile acid toxicity.

METHODS

We measured serum bile acids by gas chromatography-mass spectrometry in 13 patients with fulminant liver failure and five patients with acute-on-chronic liver failure. Furthermore, serum bile acids were analysed in the same patients after 6 h of treatment with a bioartificial liver, consisting of a hollow-fibre cartridge with microcarrier-attached porcine hepatocytes and a charcoal column.

RESULTS

Pre-bioartificial liver serum bile acids demonstrated a high dihydroxy/trihydroxy ratio and were higher in patients with acute-on-chronic liver failure than in those with fulminant liver failure (452.8 +/- 98.6 vs. 182.1 +/- 39.7 micro mol/L; P < 0.05). Bioartificial liver treatment decreased significantly serum bile acids in patients with fulminant liver failure (-38.8%) and acute-on-chronic liver failure (-35.8%), with a decreased dihydroxy/trihydroxy ratio. In vitro, porcine hepatocytes in the bioreactor cleared most conjugated bile acid species from pooled patient plasma.

CONCLUSIONS

Acute liver failure is associated with very high serum levels of toxic bile acids that could contribute to the pathogenesis of the syndrome. Bioartificial liver treatment reduces both serum bile acid concentrations and the hydrophobicity of the bile acid pool.

Fibrates suppress chenodeoxycholic acid-induced RANTES expression through inhibition of NF-kappaB activation

Fibrates, hypolipidemic agents, are reported to be effective in treatment of primary biliary cirrhosis. However, the mechanism involved in therapeutic benefits of fibrates in primary biliary cirrhosis remains unknown. In contrast, hepatic regulated upon activation, normal T-cell expressed and secreted (RANTES) is increased in patients with primary biliary cirrhosis and bile acids up-regulate RANTES expression in hepatocytes. The role of fibrates in bile acid-induced RANTES expression was investigated in human hepatoma cells; 100 microM of bezafibrate and fenofibrate decreased expression of chenodeoxycholic acid-induced RANTES mRNA and protein. In addition, luciferase enzyme assay using RANTES promoter-luciferase reporter plasmid revealed that 100 microM of bezafibrate and fenofibrate transcriptionally reduced chenodeoxycholic acid-induced RANTES gene expression. Moreover, bezafibrate clearly repressed DNA-binding activity of nuclear factor-kappaB (NF-kappaB) induced by chenodeoxycholic acid. Therefore, fibrates might be inhibitory agents of inflammatory cell migration by RANTES to the liver in patients with primary biliary cirrhosis, possibly indicating that fibrates are therapeutic agents in primary biliary cirrhosis.

Ursodeoxycholic acid for primary biliary cirrhosis

BACKGROUND

Primary biliary cirrhosis is a rare autoimmune liver disease and an effective treatment has been difficult to establish. Some randomised clinical trials have found an effect of ursodeoxycholic acid for primary biliary cirrhosis.

OBJECTIVES

Evaluate the beneficial effects and adverse effects of peroral ursodeoxycholic acid for primary biliary cirrhosis versus placebo or no intervention.

SEARCH STRATEGY

The Controlled Trials Register of The Cochrane Hepato-Biliary Group, The Cochrane Library, MEDLINE, EMBASE and the full text of the identified studies were searched until April 2001. The electronic searches were done by entering the search terms 'ursodeoxycholic acid', 'UDCA', 'primary biliary cirrhosis', and 'PBC'.

SELECTION CRITERIA

Randomised clinical trials evaluating ursodeoxycholic acid administered perorally at any dose versus placebo or no intervention in patients with primary biliary cirrhosis diagnosed by any method. Only trials using an adequate method for randomisation were included, regardless of blinding and language.

DATA COLLECTION AND ANALYSIS

The methodologic quality of the randomised clinical trials was evaluated by components and the Jadad-score. The following outcomes were extracted: mortality, liver transplantation, pruritus, other clinical symptoms (jaundice, portal pressure, (bleeding) oesophageal varices, ascites, hepatic encephalopathy, hepato-renal syndrome, autoimmune conditions), liver biochemistry, liver function, liver biopsy findings, quality of life, and adverse events. All analyses were performed according to the intention-to-treat method.

MAIN RESULTS

A total of 16 randomised clinical trials evaluating ursodeoxycholic acid against placebo (n = 15) or no intervention (n = 1) in 1422 patients were identified. The median Jadad-score was 3 (range 1-5). A number of trials described as double blind had problems with the blinding. Neither mortality (odds ratio = 0.94; 95% confidence interval (CI) 0.60 to 1.48), liver transplantation (odds ratio = 0.83; 95% CI 0.52 to 1.32), mortality or liver transplantation (odds ratio = 0.90; 95% CI 0.65 to 1.26), pruritus, fatigue, autoimmune conditions, quality of life, liver histology, or portal pressure were significantly affected by ursodeoxycholic acid (given in doses of 8-15 mg/kg/day for three months to five years). However, ursodeoxycholic acid significantly (P < 0.05) reduced ascites, jaundice, and biochemical variables such as serum bilirubin and liver enzymes. Ursodeoxycholic acid was not significantly associated with adverse events. Including data after patients had been switched onto open label ursodeoxycholic acid confirmed the findings regarding the lack of a significant effect of ursodeoxycholic acid on mortality and mortality or liver transplantation. A significant (P = 0.04) effect was, however, observed on the incidence of liver transplantation (odds ratio = 0.68; 95% CI 0.48 to 0.98).

REVIEWER'S CONCLUSIONS

Ursodeoxycholic acid has a marginal therapeutic effect for primary biliary cirrhosis. On the positive side, ursodeoxycholic acid has few side effects. The general usage of ursodeoxycholic acid for primary biliary cirrhosis needs reevaluation.

Bile acids regulate RANTES gene expression through its cognate NF-kappaB binding sites

Regulated upon activation, normal T-cells expressed and secreted (RANTES) mainly migrates memory type CD4+ T-lymphocytes to inflamed tissues. In this study, we examined effects of bile acids on RANTES gene expression in human hepatoma cells. Upon stimulation with hydrophobic bile acids, RANTES proteins were clearly increased. Semiquantitative RT-PCR analysis revealed that chenodeoxycholic acid (CDCA) induced RANTES mRNA expression. Moreover, RANTES was transcriptionally induced in two hepatoma cell lines by CDCA, presumably via its cognate NF-kappaB binding sites in the RANTES promoter. Electrophoretic mobility shift assay revealed that hydrophobic bile acids induced DNA-binding activity of NF-kappaB. Additionally, the magnitude of inducibility was closely associated with the hydrophobicity of bile acids. In conclusion, we might indicate that bile acids induced RANTES gene expression in human hepatoma cells, possibly suggesting that bile acids play an important role in migration of inflammatory cells by RANTES to the liver in patients with primary biliary cirrhosis.

A preliminary trial of high-dose ursodeoxycholic acid in primary sclerosing cholangitis

BACKGROUND & AIMS

Ursodeoxycholic acid (UDCA) is used for the treatment of cholestatic liver diseases including primary biliary cirrhosis (PBC) for which it has a positive effect on laboratory values, may delay the development of liver failure and prolong the transplant-free disease period. Standard doses of UDCA (8-15 mg/kg daily) have been shown to be ineffective in the treatment of primary sclerosing cholangitis (PSC). We report on the findings (clinical, biochemical, histological, and cholangiographic) and side effects of a 2-year double-blind placebo-controlled preliminary study of high-dose UDCA in PSC patients.

METHODS

Twenty-six patients with PSC were randomized to high-dose (20 mg/kg daily) UDCA or placebo. Cholangiography and liver biopsy were performed at entry and after 2 years. Symptoms, clinical signs, and liver biochemical tests were recorded at 3 monthly intervals.

RESULTS

High-dose UDCA did not influence symptoms, but there was a significant improvement in liver biochemistry (serum alkaline phosphatase, P = 0.03; gamma-glutamyl transferase, P = 0.01) and a significant reduction in progression in cholangiographic appearances (P = 0.015) and liver fibrosis as assessed by disease staging (P = 0.05). In the treatment group, a significant increase in total bile acids and saturation with UDCA >70% confirmed patient compliance. No significant side effects were reported.

CONCLUSIONS

High-dose UDCA may be of clinical benefit in PSC, but trials with a larger number of participants and of longer duration are required to establish whether the effect of high-dose UDCA on liver biochemistry, histology, and cholangiography in patients with PSC is translated into improved long-term survival.

Differences in the efficacy of ursodeoxycholic acid and bile acid metabolism between viral liver diseases and primary biliary cirrhosis

AIM AND METHODS

The effects of ursodeoxycholic acid (UDCA, 600 mg/day) on liver function test values, and serum and urinary bile acids levels in hepatitis C virus-related chronic hepatitis (CH, n = 39) and liver cirrhosis (LC, n = 25), and in primary biliary cirrhosis (PBC, n = 25) were compared.

RESULTS

The percentages of improvement in alanine transaminase (ALT) and gamma-glutamyl transpeptidase (gamma-GTP) in CH were almost the same in LC. The rates of improvement in ALT in PBC were negatively correlated with histological stages in the liver. Total serum bile acid levels in LC rose to the same extent as in CH, but the increases in PBC were significantly smaller at stages 3-4 than stages 1-2. The urinary levels of hydroxylated metabolites of UDCA only slightly increased in LC, but they increased significantly at PBC stages 3-4.

CONCLUSIONS

The efficacy of UDCA was preserved in LC, but diminished at PBC stages 3-4. The poor enrichment of UDCA in the bile acid pool and extensive biotransformation of UDCA may cause the limited efficacy of UDCA in the cirrhotic stage of PBC.

Use of ursodeoxycholic acid in liver diseases

Ursodeoxycholic acid is currently the only established drug for the treatment of chronic cholestatic liver diseases. It has cytoprotective, anti-apoptotic, membrane stabilizing, anti-oxidative and immunomodulatory effects. Prolonged administration of ursodeoxycholic acid in patients with primary biliary cirrhosis (PBC) is associated with survival benefit and a delaying of liver transplantation. There is evidence that it might even prevent progression of the histologic stage of PBC. It also has a beneficial effect on primary sclerosing cholangitis, intrahepatic cholestasis of pregnancy, liver disease associated with cystic fibrosis, chronic graft versus host disease, total parenteral nutrition associated cholestasis and various pediatric cholestatic liver diseases. In the present review the current knowledge about the mechanisms of the action and role of ursodeoxycholic acid in the treatment of various liver diseases has been discussed.

Abnormal hepatic sinusoidal bile acid transport in an Amish kindred is not linked to FIC1 and is improved by ursodiol

BACKGROUND & AIMS

The mechanism for abnormal hepatic bile acid transport was investigated in an 18-month-old Amish boy who presented with pruritus, poor growth, and severe bleeding episodes. Serum bilirubin, gamma-glutamyltranspeptidase, and cholesterol levels were normal, but prothrombin time and partial thromboplastin time were prolonged and bone alkaline phosphatase level was elevated.

METHODS AND RESULTS

Cholic acid plus chenodeoxycholic acid levels measured by capillary gas-chromatography were 32 times higher than control in serum (34.7 vs. 1.1+/-0.4 microg/dL) but were not detected in liver and were reduced in gallbladder bile. Treatment with ursodiol, a more hydrophilic bile acid, improved pruritus, produced 37% weight gain, and after 2 years reduced serum primary bile acid concentrations about 85%, while accounting for 71% of serum and 24% of biliary bile acid conjugates. On ursodiol therapy, hepatic bile acid synthesis was enhanced 2-fold compared with controls, and microscopy revealed chronic hepatitis without cholestasis. Three younger sisters with elevated serum bile acids responded positively to ursodiol. Microsatellite markers for the FIC1 (gene for Byler's disease) region in these 4 children were inconsistent with linkage to FIC1.

CONCLUSIONS

Conjugated cholic acid and chenodeoxycholic acid were synthesized in the liver and secreted into bile but could not reenter the liver from portal blood and accumulated in serum. In contrast, unconjugated ursodiol entered the liver and was conjugated and secreted into bile. Thus, the enterohepatic circulation of all conjugated bile acids was interrupted at the hepatic sinusoidal basolateral membrane. Unconjugated ursodiol bypassed the hepatic uptake block to enlarge the biliary and intestinal bile acid pools. A mutation in FIC1 recognized among the Amish and linkage of the disorder to FIC1 were excluded.

A convenient synthesis of dinorbile acids: oxidative hydrolysis of norbile acid nitriles

We report a convenient method for the synthesis of dinorbile acids (23,24-dinor-5beta-cholan-22-oic acids, pregnane-20-carboxylic acids) in fair to good yields from norbile acid nitriles in one step by oxidative hydrolysis with oxygen in the presence of potassium-t-butoxide. The method results in stepwise overall removal of two carbon atoms in bile acid side chains in two steps. Dinorbile acids corresponding to several common bile acids have been prepared and their structures confirmed by spectroscopic methods. This simple method for synthesis of dinorbile acids may facilitate their study metabolically.

Review article: mechanisms of action and therapeutic applications of ursodeoxycholic acid in chronic liver diseases

Ursodeoxycholic acid (ursodiol) is a non-toxic, hydrophilic bile acid used to treat predominantly cholestatic liver disorders. Better understanding of the cellular and molecular mechanisms of action of ursodeoxycholic acid has helped to elucidate its cytoprotective, anti-apoptotic, immunomodulatory and choleretic effects. Ursodeoxycholic acid prolongs survival in primary biliary cirrhosis and it improves biochemical parameters of cholestasis in various other cholestatic disorders including primary sclerosing cholangitis, intrahepatic cholestasis of pregnancy, cystic fibrosis and total parenteral nutrition-induced cholestasis. However, a positive effect on survival remains to be established in these diseases. Ursodeoxycholic acid is of unproven efficacy in non-cholestatic disorders such as acute rejection after liver transplantation, non-alcoholic steatohepatitis, alcoholic liver disease and chronic viral hepatitis. This review outlines the present knowledge of the modes of action of ursodeoxycholic acid, and presents data from clinical trials on its use in chronic liver diseases.

A paucity of unusual trihydroxy bile acids in the urine of patients with severe liver diseases

To clarify the relationship between the occurrence of unusual trihydroxy bile acids, namely hyocholic acid, ursocholic acid (UCA), and omega-muricholic acid (omega-MCA) in urine and liver disease severity, urinary bile acids were analyzed by gas-liquid chromatography in acute and late phases of acute hepatitis and before and after ursodeoxycholic acid (UDCA) loading in healthy adults and liver cirrhosis patients. In 11 patients with acute hepatitis, the occurrence rates and amounts of unusual trihydroxy bile acids were increased in the late (recovery) phase, as compared with those in the early phase. In 10 patients with severe acute hepatitis who had prothrombin times exceeding 16 seconds, these bile acids had completely disappeared from the urine in the early phase but reappeared in the late phase in those who had a good outcome, though never in a patient who died. After UDCA administration for a week, the amounts of unusual bile acids, especially UCA and omega-MCA, which are thought to be synthesized through 12 alpha- and 6 alpha-hydroxylations, respectively, from UDCA, were clearly increased in 10 healthy adults but only slightly changed in 10 patients with liver cirrhosis. In conclusion, hepatic hydroxylations of dihydroxy bile acids as a detoxification reaction were impaired in severe liver diseases, which may play a role in the intensification and perpetuation of hepatocellular injuries.

Gas chromatography of bile acids

Bile acids, the end products of cholesterol metabolism in the liver, are of vital importance in the tissue distribution of cholesterol. Abnormalities in cholesterol biosynthesis or metabolism are often reflected in the proportions, concentrations and conjugation of bile acids in various tissues and determination of bile acids in these tissues is important in the diagnosis of hepatobiliary diseases. Several methods for quantitative determination of bile acids in biological fluids are known and have been reviewed. In this review, we have discussed the gas-chromatographic method for determination of bile acids with special reference to bile acid quantitation in plasma, bile, urine and stool.

Differences in the metabolism and disposition of ursodeoxycholic acid and of its taurine-conjugated species in patients with primary biliary cirrhosis

The clinical effectiveness of ursodeoxycholate in the treatment of liver disease may be limited by its poor absorption and extensive biotransformation. Because in vitro and in vivo studies suggest that the more hydrophilic bile acid tauroursodeoxycholate has greater beneficial effects than ursodeoxycholate, we have compared for the first time the absorption, metabolism, and clinical responses to these bile acids in patients with primary biliary cirrhosis (PBC). Twelve female patients with PBC were sequentially administered tauroursodeoxycholate and ursodeoxycholate (750 mg/d for 2 months) in a randomized, cross-over study. Bile acids were measured in serum, duodenal bile, urine, and feces by gas chromatography-mass spectrometry (GC-MS). Biliary ursodeoxycholate enrichment was higher during tauroursodeoxycholate administration (32.6% vs. 29.2% during ursodeoxycholate; P <.05). Lithocholic acid concentration was consistently higher in all biological fluids during ursodeoxycholate administration. Fecal bile acid excretion was the major route of elimination of both bile acids; ursodeoxycholate accounted for 8% and 23% of the total fecal bile acids during tauroursodeoxycholate and ursodeoxycholate administration, respectively (P <.05). Tauroursodeoxycholate was better absorbed than ursodeoxycholate, and, although it was partially deconjugated and reconjugated with glycine, it underwent reduced biotransformation to more hydrophobic metabolites. This comparative study suggests that tauroursodeoxycholate has significant advantages over ursodeoxycholate that may be of benefit for long-term therapy in PBC.

In liver transplantation, T tube bile represents total bile flow: physiological and scintigraphic studies on biliary secretion of organic anions

The present study was performed to clarify the recovery of hepatocellular uptake and the biliary secretion of bile acids during the first 14 days after orthotopic liver transplantation (OLT) and to determine the fraction of bile flow appearing outside through the T tube and entering the duodenum. Therefore, we determined primary and secondary bile acids in bile samples obtained from the T tube at day 5 after OLT, while the T tube was permanently open, and at days 10 and 14 after OLT, i.e., 4 and 9 days after closure of the T tube, respectively, thus restoring enterohepatic bile acid circulation. In addition, we performed hepatobiliary scintigraphy using technetium 99m-labeled [2,4,6 trimethyl-3-bromo]imino-diacetic acid (technetium 99m-BRIDA) in 12 patients between days 4 and 17 after OLT. Chromatographic analyses of biliary bile acids showed no secondary bile acids during the first 5 days after OLT, as opposed to 10 and 14 days after OLT when enterohepatic circulation was restored. Eleven patients with an uncomplicated postoperative course after OLT showed a significantly reduced hepatic uptake and biliary secretion of 99mTc-BRIDA during the first days after OLT with progressive recovery. One patient with an acute allograft rejection episode showed almost no uptake and only minimal secretion. The bile fraction appearing outside through the inserted T tube represented 94.6% +/- 6.2% of the injected 99mTc-BRIDA. We conclude that OLT results in markedly impaired hepatocellular uptake and biliary secretion of organic anions. Simultaneously, bile acid synthesis is significantly reduced, which, in addition, diminishes bile secretion of the graft. We show that T tube bile is a valid tool for bile physiological studies in patients in whom transplantation was successfully performed.

Relationship between biliary and serum bile acids and response to ursodeoxycholic acid in patients with primary biliary cirrhosis

OBJECTIVE

Ursodeoxycholic acid (UDCA) improves liver biochemistries and enriches the bile with UDCA in patients with primary biliary cirrhosis. The aim of this study was to determine whether the degree of enrichment of bile correlated with that of serum and whether either of these measures correlated with improvement in measures of liver disease.

METHODS

In a randomized study, biliary and serum bile acid analyses were performed at entry and after 2 yr of UDCA or placebo.

RESULTS

The percentage of ursodeoxycholic acid in bile increased by 42% in the UDCA group (n = 61) compared with 8% in the placebo group (n = 57) (p < 0.0001). Measurement of serum bile acids in 32 patients (18 ursodeoxycholic acid, 14 placebo) indicated that at 2 yr, ursodeoxycholic acid comprised 65% of serum bile acids in the treated group and 7% in the placebo group. Agreement between bile and serum was fair (r = 0.75, p < or = 0.00002) because in some patients, plasma but not biliary bile acids were enriched with UDCA. Changes in biliary ursodeoxycholic acid correlated significantly but weakly with the changes in serum alkaline phosphatase, AST, bilirubin, and in Mayo risk score. Correlations between changes in serum bile acid composition and biochemical measures of disease activity were even weaker.

CONCLUSION

The measurement of biliary bile acids is superior to that of serum bile acids for assessing the compliance and changes in the circulating bile acids in patients receiving ursodeoxycholic acid for the treatment of primary biliary cirrhosis. Furthermore, measures to further increase the proportion of ursodeoxycholic acid in circulating bile acids should be explored.

Biliary cholesterol excretion: a novel mechanism that regulates dietary cholesterol absorption

The regulation of dietary cholesterol absorption was examined in C57BL/6 and transgenic mice with liver overexpression of the scavenger receptor BI (SR-BI Tg). In C57BL/6 animals, feeding 0.02 to 1% (wt/wt) dietary cholesterol resulted in a dose-dependent decrease in the percentage of dietary cholesterol absorbed. A plot of total daily mass of dietary cholesterol absorbed versus the percentage by weight of cholesterol in the diet yielded a curve suggesting a saturable process with a Km of 0.4% (wt/wt) and a Vmax of 0.65 mg cholesterol/g body weight per day. Dietary cholesterol suppressed hepatic 3-hydroxy-3-methylglutaryl CoA reductase activity, stimulated cholesterol 7alpha-hydroxylase activity, and enhanced fecal excretion of bile acids, but none of these changes correlated with the percentage of dietary cholesterol absorption. Dietary cholesterol also caused an increase in biliary cholesterol concentration, and in this case the concentration of biliary cholesterol was strongly and inversely correlated with the percentage dietary cholesterol absorption (r = -0.63, P < 0.0001). Biliary cholesterol concentration was also directly correlated with daily cholesterol intake, dietary cholesterol mass absorption, and liver cholesterol ester content. Transgene-induced overexpression of SR-BI resulted in a stimulation of excretion of cholesterol into the bile and suppressed percentage dietary cholesterol absorption. Furthermore, biliary cholesterol levels in SR-BI Tg mice were strongly and inversely correlated with the percentage of dietary cholesterol absorbed (r = -0.99, P < 0.0008). In summary, these results suggest that the excretion of cholesterol into the bile plays an important role in regulating the percentage absorption of dietary cholesterol.

Management of primary biliary cirrhosis and autoimmune cholangitis

Several drugs have been evaluated in the treatment of primary biliary cirrhosis over a number of years. These drugs have immunosuppressive, antiinflammatory, cupruretic, antifibrotic and bile acid properties. Ursodeoxycholic acid has been shown to improve survival free of transplantation in a conclusive fashion. This drug is the single agent that can be recommended for the treatment of primary biliary cirrhosis. Corticosteroid therapy and ursodeoxycholic acid have been evaluated in a few patients with autoimmune cholangitis. This article reviews a large number of studies that have been published assessing different drugs in the treatment of these two entities, particularly in the treatment of primary biliary cirrhosis.