Effects of bile acids on the humoral immune response: a mechanistic approach.

Whereas bile acids in excess depress the cell-mediated immune response, their effects on the humoral response have been little investigated. The aim of this study was to investigate the effects of bile acids on immunoglobulin production. Human peripheral blood mononuclear cells were stimulated for 5 days by Staphylococcus aureus Cowan I (SAC-I). Immunoglobulins were measured in the supernatants and cell lysates using ELISA. We found that bile acids inhibited IgM production in a dose-dependent manner. The inhibitory effects of 50 microM chenodeoxycholic acid (CDCA) and its glyco- and tauro-conjugates (62, 53 and 51%, respectively) were stronger than those of ursodeoxycholic acid (UDCA) and its conjugates (45, 40 and 34%, respectively). The inhibition of IgG production by CDCA and UDCA was weak (23 and 12%, respectively, at 50 microM). IgA production was not modified. The inhibition of intracellular IgM concentration paralleled that observed in the secreted compartment. By contrast, CDCA enhanced intracellular concentration of IgG. In the absence of significant necrosis or apoptosis, CDCA-mediated inhibition of SAC-I-induced IgM production was significantly correlated to the ability of the bile acid to inhibit cell proliferation (r=0.98; p<0.05). In conclusion, we showed that hydrophobic bile acids strongly depress the primary humoral response. This effect resulted from both an inhibition of cell proliferation, and to a lesser extent from a deficient exocytosis of immunoglobulins.

[Ursodeoxycholic acid and prevention of tacrine-induced hepatotoxicity: a pilot study]. / Acide ursodésoxycholique et prévention de l'hépatotoxicité de la tacrine: une étude pilote.

Ursodeoxycholic acid is a protective agent against liver toxicity caused by some drugs. In the present pilot study, we assessed the effect of this bile acid on tacrine-induced hepatotoxicity. Fourteen patients with a diagnosis of Alzheimer's disease received tacrine and ursodeoxycholic acid (13 mg/kg/day) for 105 days. Serum ALAT was the main evaluation criterion. Serum levels of ALAT were compared with those of 100 patients who had been treated with tacrine in the same centre. In patients receiving ursodeoxycholic acid, ALAT serum levels were normal in 93 per cent of cases vs. 69 per cent in control patients and moderate hepatotoxicity (ULN < ALAT < 3 ULN) did not occur while it was present in 25 per cent of controls (p = 0.036). In contrast, the percentage of patients with ALAT > 3 ULN was similar in the two groups (7 per cent vs. 6 per cent). These present findings suggest that UDC could prevent moderate tacrine-induced hepatotoxicity. These results should be confirmed in a controlled therapeutical trial.

Role of fibrates and HMG-CoA reductase inhibitors in gallstone formation: epidemiological study in an unselected population.

Fibrate derivatives and HMG-CoA reductase inhibitors modify homeostasis of cholesterol. The aim of this study was to assess in an unselected population whether these hypolipidemic drugs are risk factors for cholelithiasis or, conversely, are protective agents. Both sexes, all socioeconomic categories, pregnant women, and cholecystectomized subjects were included. Clinical data collection and gallbladder ultrasonography were both carried out in a double-blind fashion. Fibrate derivatives were predominantly fenofibrate, HMG-CoA reductase inhibitors were simvastatin and pravastatin. On univariate analysis, age (>50 years), sex, and use of fibrates were found to be significantly related to the presence of cholelithiasis. Age, sex, and fibrate treatment remained independently correlated with the presence of gallstones on multivariate analysis. With fibrates, the relative risk for lithiasis was 1.7 (P = 0.04). The HMG-CoA reductase inhibitors were not associated with a protective effect on univariate analysis. Of the lipid-lowering drugs, only fibrate derivatives were found to increase the risk of gallstone formation.

Effects of bile salts and aliphatic ionic surfactants on human lymphocyte proliferation.

BACKGROUND: The molecular mechanisms involved in the immunosuppressive properties of bile salts are partly unknown. METHODS: The aim of the study was to compare the effects of bile salts to those of various compounds with a steroid structure, or straight-chain hydrocarbons of different lengths and polar groups in the human mixed lymphocyte reaction. RESULTS: We showed a significant correlation between the effects of bile salts and a low critical micellar concentration, a high surface activity index, and the absence of conjugation. In addition to mixed lymphocyte reaction (MLR) inhibition, chenodeoxycholate (CDC) inhibit ConA-induced IL2 production without any effect on IL2 R expression. Fusidate, a negatively charged steroid, with physical properties comparable to those of deoxycholate, had similar effects. Cetyltrimethylammonium bromide (CTAB), which exhibited a very low critical micellar concentration, inhibited mixed lymphocyte reaction in an extent comparable to cyclosporin A. In contrast, aliphatic compounds with critical micellar concentrations in the same range as bile salts but with a lower molecular area had no effect. CONCLUSIONS: Amphiphilic negatively charged molecules inhibit T-cell proliferation to an extent that is dependent upon their hydrophobicity. These results may be explained, at least in part, by a modification in the cell membrane lipid bilayer structure.

Ursodeoxycholic acid modulates cyclosporin A oral absorption in liver transplant recipients.

The aim was to study the ursodeoxycholic acid (UDC) effect on the cyclosporin A (CsA) pharmacokinetics after oral administration of the microemulsion formulation Neoral (CsA-ME) in liver transplant recipients, and test the potential protective effect of this bile acid on liver and renal CsA-ME-induced toxicity. At entry into the study, 12 patients who underwent orthotopic liver transplantation received CsA-ME, for at least 6 months. They then received a cotreatment CsA-ME plus UDC (13.8 mg x kg(-1) x day(-1)) for three months. Blood concentrations of CsA were measured using a monoclonal antibody specific for the parent compound. The kinetic data were analysed by a mathematical model incorporating a time dependent rate coefficient for CsA intestinal absorption, before and after UDC treatment. Changes in serum markers of hepatic and renal injury were assessed. Individual serum bile acids were determined by chromatography. Serum levels of UDC increased from 3 to about 45% of total serum bile acids after UDC treatment. The estimated model parameters indicate that UDC administration modulates CsA intestinal absorption. In the nine non-cholestatic patients, UDC reduced the absorption rate and the bioavailability of CsA without modifying the elimination rate constant of CsA and the CsA pre-drug levels. In contrast, in the three cholestatic patients, the bioavailability tended to be higher and the absorption rate faster when CsA was combined with UDC. UDC significantly decreased elevated gamma-glutamyl transferase and creatinine serum levels and induced some clinical improvements such as disappearance of headaches in four patients. In conclusion, a 3-month UDC treatment modifies CsA intestinal absorption without affecting CsA elimination rate constant. On the other hand, UDC supplementation appears to improve CsA tolerability.

Effect of endoscopic sphincterotomy on bile lithogenicity in patients with gallbladder in situ.

BACKGROUND AND STUDY AIMS: Endoscopic sphincterotomy results in a continuous flow of bile into the duodenum and consequently leads to an increase in the frequency of enterohepatic bile acid cycling. Because bile acids are the driving force of biliary secretion, sphincterotomy may affect bile genesis. The present study was undertaken to determine the influence of endoscopic sphincterotomy on bile composition. PATIENTS AND METHODS: The cholesterol saturation index and the bile acid pattern were determined in the gallbladder bile of lithiasis patients with (group III) or without sphincterotomy (group I), and in the hepatic bile of patients with gallbladder in situ who were checked at 3 months after the endoscopic procedure (group II). Stones from each patient were examined for chemical composition and microstructure. RESULTS: All the patients had cholesterol stones. After endoscopic sphincterotomy the molar percentages of cholesterol in the gallbladder bile of group III and in the hepatic bile of group II were significantly lower (-31% and -46% respectively) than in group I. Similarly, the cholesterol saturation index in the hepatic bile (0.79) and the gallbladder bile (0.86) from patients who had undergone sphincterotomy indicated undersaturation whereas bile from group I was oversaturated (1.25). On the other hand, endoscopic sphincterotomy did not modify the hydrophobicity index of the bile acid pool, even though deoxycholate content increased. CONCLUSIONS: Endoscopic sphincterotomy causes a marked decrease in the lithogenicity of bile and thus may prevent the risk of recurrence of cholesterol lithiasis.

CYP2E1 and CYP3A1/2 gene expression is not associated with the ursodeoxycholate effect on ethanol-induced lipoperoxidation.

Ethanol is a well-known hepatotoxicant inducing steatosis and membrane lipoperoxidation. The aim of the present study was to investigate in rats, whether the protective effect of UDC on ethanol-induced lipid peroxidation may be related with CYP2E1 and CYP3A1/2 gene expression. We showed that UDC treatment in ethanol-fed rats induced a significant decrease in liver triglyceride concentration which was closely correlated with a reduction in malondialdehyde and hydroxyalkenal levels. In chronically ethanol-fed rats, CYP2E1 and CYP3A1/2 gene expressions were increased by a post-transcriptional mechanism. These inductions, mainly of CYP2E1, could take part in alcohol-induced hepatic lipoperoxidation. UDC modified neither the specific activity, nor the protein level, nor the mRNA level of CYP2E1 when compared with control. UDC supplementation to alcohol diet did not prevent the increase in CYP2E1 expression of ethanol-fed rats. Furthermore, CYP3A1/2 protein levels were similarly increased by ethanol and ethanol plus UDC treatment. Therefore, UDC protective effect against ethanol-induced lipoperoxidation was not associated with a modification of CYP2E1 and CYP3A1/2 expression.

Gallbladder volume in adults and its relationship to age, sex, body mass index, body surface area and gallstones. An epidemiologic study in a nonselected population in France.

BACKGROUND/AIMS: The role of a large gallbladder volume with regard to a predisposition for gallstones is unknown. It is possible that an increase in gallbladder volume could result in impaired gallbladder motility and bile stasis. We looked for factors affecting gallbladder volume in a random population in the southeast of France. METHODS: To assess the relationship between gallbladder volume and gallstones, 528 subjects over the age of 30 were studied (72 with lithiasis). Age, sex, body mass index, body surface area and gallbladder volume were collected for each subject. A linear regression analysis was performed to look for significant variables. RESULTS: The overall adjusted prevalence of cholelithiasis was 13.9% in our population. On linear regression analysis, two variables (age and surface area) were found to be independently correlated with gallbladder volume. Gallbladder volume was significantly increased in subjects over 50 years (p < 0.001). There was a positive correlation between gallbladder volume and body surface area (r = 0. 33, p < 0.001). In this study, the presence or absence of gallstones did not significantly affect the gallbladder volume. CONCLUSIONS: We report that there is dilatation of the gallbladder with age and with an increase in body surface area. Whether this could represent risk factors for the occurrence of gallstone remains uncertain.

Ursodeoxycholate protects against ethanol-induced liver mitochondrial injury.

The purpose of this work was to examine whether ursodeoxycholate (UDC), a hydrophilic bile salt, could reduce mitochondrial liver injury from chronic ethanol consumption in rats. Animals were pair-fed liquid diets containing 36% of calories as ethanol or isocaloric carbohydrates. They were randomly assigned into 4 groups of 7 rats each and received a specific treatment for 5 weeks: control diet, ethanol diet, control diet + UDC, and ethanol diet + UDC. Respiratory rates of isolated liver mitochondria were measured using a Clark oxygen electrode with sodium succinate as substrate. Mitochondria from rats chronically fed ethanol demonstrated an impaired ability to produce energy. At the fatty liver stage, the ADP-stimulated respiration (V3) was depressed by 33%, the respiratory control ratio (RC) by 25% and the P/O ratio by 15%. In ethanol-fed rats supplemented with UDC, both the rate and efficiency of ATP synthesis via the oxidative phosphorylation were improved: V3 was increased by 35%, P/O by 8%. All the respiratory parameters were similar in control group and control + UDC group. On the other hand, the number and size of mitochondria were assessed by electron microscopy and computer-assisted quantitative analysis. The number of mitochondria from ethanol-treated rats was decreased by 29%, and they were enlarged by 74%. Both parameters were normalized to control values by UDC treatment. These studies demonstrate that UDC has a protective effect against ethanol-induced mitochondrial injury by improving ATP synthesis and preserving liver mitochondrial morphology. These UDC positive effects may contribute to the observed decrease in fat accumulation and may delay the progression of alcoholic injury to more advanced stages.

Ursodeoxycholate alleviates alcoholic fatty liver damage in rats.

The hydrophilic bile salt ursodeoxycholate (UDC) improves cholestasis in several liver diseases and is in vitro an efficient membrane stabilizer. However, its action on chronic ethanol-induced liver damage is not established. We thus sought to determine the effect of UDC on chronic ethanol-induced steatosis and on liver plasma membrane fluidity in rats. Male rats were pair-fed liquid diets containing 36% of calories as ethanol (alcohol diet) or an isocaloric maltose-dextrin mixture (control diet). Four groups of 10 animals received, respectively, during 30 days: the control diet, the control diet + UDC (90 mg/kg/day), the alcohol diet, and the alcohol diet + UDC. Bile was collected for assessment of bile flow, biliary lipids, and individual bile salts. Liver lipid contents and lipid peroxidation were determined. Plasma membrane fluidity was assessed by fluorescence polarization of various probes. Alcohol treatment caused a 4-fold increase in liver triacylglycerol and cholesterol ester levels. UDC supplementation significantly reduced these increases by 50% and 40%, respectively. UDC intake was associated with a marked decrease in alcohol-induced lipid peroxidation. Bile flow, bile salt, and phospholipid secretion were slightly increased by alcohol intake. The addition of UDC-enriched bile with tauroursodeoxycholate (38%) without significantly affecting the biliary parameters. Lastly, UDC treatment almost totally prevented the 20% increase in liver plasma membrane fluidity due to chronic alcohol intake. This study shows that UDC intake, concomitant with alcohol diet, exerts a clear-cut membrane protective effect that might alleviate ethanol-induced lipid disorders.

Effects of tauroursodeoxycholate solutions on cyclosporin A bioavailability in rats.

Cyclosporin A (CsA) exhibits poor bioavailability after oral administration of Sandimmune, with wide intra- and interindividual variations. Our study sought to determine the effect of the coadministration of CsA standard oily formulation and tauroursodeoxycholate (TUDC) and that of an aqueous micellar solution containing TUDC, monoolein, and CsA in promoting and regulating CsA bioavailability in the rat Pharmacokinetic parameters of CsA were determined in fasted rats after either an intravenous administration (5 mg/kg) or a single oral CsA dose of 10 mg/kg. Compared with oral Sandimmune, the CsA micellar solution significantly improved the CsA bioavailability by 160% and decreased the interindividual variability in bioavailability expressed as percent coefficient of variation from 32% to 15%. The concentration-time profile was modified with a 3.5-fold increase in C(max), a reduction of t(max), and an increased trough concentration. Bioavailability slightly improved in rats receiving standard oily solution plus concomitant TUDC, although not significantly. Data indicate that the structure of the CsA carriers greatly affect drug bioavailability and that aqueous micellar solutions of CsA-TUDC-monoolein constitute efficient vehicles, thus providing for CsA high absorption with low variability.

[Contact litholysis of common bile duct calculi. Study of 44 patients]. / Litholyse de contact des calculs de la voie biliaire principale. Etude chez 44 malades.

OBJECTIVES: Endoscopic sphincterotomy has become a generally accepted method for extracting common bile duct stones in high risk or cholecystectomized patients. However, stone extraction is impossible by the usual methods in 5 to 10% of cases. The purpose of this study was to evaluate the effect of a recently developed solvent system in patients with large bile duct stones. METHODS: Forty four patients (15 men and 29 women, median age of years) underwent contact dissolution after unsuccessful Dormia extraction. Solvents were administered via a nasobiliary catheter in 41 patients following papillotomy and through a T-tube in 3 patients. Solvent mixtures (26 mM ethylene diamine tetraacetic acid, 40 mM sodium deoxycholate and 30% dimethyl sulfoxide in an alkaline aqueous solution; and a 70/30 dimethyl sulfoxide/methyl tert-butyl ether mixture) were infused continuously and alternatively for 2 hours. RESULTS: Bile duct stones disappeared in 13-24 hours of infusion in 11 patients. In 29 patients, a clear reduction in stone volume occurred, allowing complete endoscopic extraction of the fragments. In 4 patients, the size of the stone did not change. Only mild and transient side-effects including abdominal pain (68%), nausea (72%), vomiting (52%), diarrhea and sleepiness (50%) were observed. CONCLUSION: Direct dissolution therapy could be an effective method for the non-surgical management of large bile duct stones in selected patients when intra- or extracorporeal lithotripsy is unsuccessful.

Ursodeoxycholate improves hepatobiliary dysfunction induced by valproate-carbamazepine treatment in the rat.

Carbamazepine (CBZ) and valproate (VPA) are commonly used antiepileptic drugs. These drugs, either alone or combined, may produce hepatotoxicity. We report results of a biochemical and histological study of the liver in rats treated for eight days with VPA (500 mg/Kg/day), CBZ (200 mg/Kg/day) and VPA plus CBZ. A hepatoprotective bile salt, ursodeoxycholate (UDC, 60 mg/Kg/day) was given as a supplement to rats treated with the VPA+CBZ combination. VPA strongly modified the biliary biochemical parameters inducing hypercholeresis and hyposecretion of phospholipids. Microscopically, hepatocytes showed intense vacuolation of the peripheral cytoplasm and alterations of the mitochondrial matrix. CBZ produced increased choleresis but had no effect on biliary lipid parameters. Ultrastructurally, CBZ induced marked proliferation of the smooth endoplasmic reticulum of hepatocytes. The VPA+CBZ association produced a combination of the alterations induced independently by each drug. In both bile and plasma, increased CBZ-epoxide and decreased VPA levels were observed. The addition of UDC restored the biliary phospholipid secretion, decreased cytoplasmic vacuoles and mitochondrial alterations, and diminished the hypertrophy of smooth endoplasmic reticulum, indicating a clear beneficial effect of UDC on hepatobiliary dysfunction induced by the VPA+CBZ combination. Furthermore, the supplementation with UDC did not significantly change the plasma levels of the antiepileptic drugs.

Contact solvents for common bile duct stones. Study in an in vitro system.

Cholesterol and brown pigment stones found in the common bile duct are often radiolucent and therefore indistinguishable. The purpose of this study was to define contact solvent systems able to dissolve both stone types. The influence of mucolytic agents on in vitro pigment stone dissolution was first determined. It was shown that dithioerythritol induced more rapid dissolution than N-acetylcysteine. Alternating treatment with an aqueous alkaline solvent (pH = 9.5), composed of sodium deoxycholate 50 mM, ethylenediaminetetraacetate 26 mM and dithioerythritol 50 mM, for 45 min, and an organic solvent methyl tert-butyl ether/dimethyl sulfoxide (90/10) for 15 min, was more effective for bilirubin, cholesterol, and fatty acid solubilization (p < 0.01) than using these solvents separately. The dissolution of brown stones was nearly completed within 9 h and that of mixed cholesterol stones was obtained within 3 h. We conclude that the alternating treatment described is very effective for the rapid in vitro dissolution of the two major stone types present in the bile ducts, and deserves further assessment in vivo.

[Direct dissolution therapy of biliary tract calculi]. / Az epeúti kövesség direkt oldószeres kezelése.

The aim of this study was to evaluate the effect of a recently developed biphasic multicomponent solvent in 39 patients with biliary duct stones that are too large (15-35 mm) to be removed after endoscopic sphincterotomy. From November 1991 to October 1993, 37 patients with common bile duct stones were papillotomized during endoscopic retrograde cholangiography and a nasobiliary catheter was positioned above the stone. In 2 patients, the residual stones were dissolved via the T-tube inserted during cholecystectomy. Solvent mixtures (solvent 1:26 mM ethylene diamine tetraacetic acid, 40 mM sodium deoxycholate and 30% dimethyl sulfoxide in an aqueous buffer solution glycine-NaOH, pH: 9.2; solvent 2: a 70: 30 mixture of dimethyl sulfoxide and methyl-tert-butyl-ether) were infused continuously and alternatively for 2 h at a rate of 0.3-0.5 ml/kg b.w./h. In order to diminish the absorption of the solvent from the duodenum, charcoal was given orally periodically. Fluoroscopy indicated that the common bile duct stones disappeared during 13-24 h of infusion in 10 of 39 patients. In 25 patients, the size of the stones diminished sufficiently for them to be removed by basket extraction. In 4 patients, the size of the stone did not change and surgery (1 pt) or endoscopic stenting (3 pts) was required. Only mild toxic side-effects were observed, including laboratory abnormalities and moderate duodenitis (34/39). Transient abdominal pain and/or cramp (21/39), nausea and vomiting (34/39) and diarrhoea (19/39) were the most common complaints during treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvement of cyclosporin A-induced cholestasis by tauroursodeoxycholate in a long-term study in the rat.

Cyclosporin A is an essential immunosuppressive drug, but it is potentially toxic to the kidney and liver. Ursodeoxycholic acid, a hydrophilic bile acid, has been reported to improve cholestasis in liver disease in man. The purpose of this work was to examine whether tauroursodeoxycholate could reduce cyclosporin A-induced hepatic or renal injuries in the rat. After randomization into three groups (N = 8), rats received daily for 17 days: cyclosporin A intraperitoneally alone (30 mg/kg) or cyclosporin A intraperitoneally and tauroursodeoxycholate (60 mg/kg) by gavage; control received the cyclosporin A excipient. Under tauroursodeoxycholate, cholestatic parameters (bile flow, bile salt secretion, serum bile salts, serum bilirubin) improved significantly without affecting cyclosporin A blood levels, and excretion of the drug and its metabolites in bile increased by 47%. Serum creatinine levels were better preserved, although not significantly. These results show that tauroursodeoxycholate prevents cyclosporin A-induced cholestasis in long-term treatment in rats, possibly by facilitating the drug elimination in bile.

Diminution of an acute cyclosporin-induced cholestasis by tauroursodeoxycholate in the rat.

CsA is a commonly used immunosuppressive drug known to possibly induce cholestatic side effects. Ursodeoxycholic acid (UDC), a nonhepatotoxic bile acid, has proved to be efficient for several types of cholestasis. The aim of this experiment was to evaluate the ability of tauroursodeoxycholate (TUDC) in preventing CsA-induced cholestasis on bile duct-cannulated rats. After bile flow stabilization, a bolus of 30 mg/kg CsA was given i.v. to one group (n = 7) and was associated with a 2 mumol/kg/min TUDC infusion in another group (n = 7). The control group was injected with CsA-solvent. CsA, as used here, had a rapid and marked cholestatic effect. However, both bile flow and bile salt secretion were significantly enhanced in the TUDC group when compared to the CsA alone-treated group and showed no difference with the solvent control group. In addition, TUDC significantly increased elimination of CsA and its metabolites in bile. In contrast to what was found for endogenous bile salts, TUDC uptake was not affected by CsA. The anticholestatic effect of TUDC probably resulted from preventing CsA-induced hepatocyte membrane damage and from easing biliary excretion of CsA. Such properties could be helpful for CsA-treated liver recipients who are especially exposed to cholestatic problems, and thus, to toxic CsA accumulation in the liver. Moreover, regulation of CsA elimination might prevent, in part, its general toxicity.

Effects of ursodeoxycholic acid on liver function in patients with cystic fibrosis and chronic cholestasis.

Ursodeoxycholic acid, 10 to 20 mg/kg per day, was administered for 1 year to 22 patients with cystic fibrosis and chronic cholestasis, resulting in significantly improved liver enzyme values. However, evidence of cholestasis continued, as shown by the pattern of alkaline phosphatase isoenzymes.