Effect of chronic administration of ursodeoxycholic acid on the ileal absorption of endogenous bile acids in man

The role of bile acid in intestinal metaplasia

A precancerous lesion of gastric cancer (GC), intestinal metaplasia (IM) is a pathological transformation of non-intestinal epithelium into an intestinal-like mucosa. It greatly raises the risk of developing the intestinal type of GC, which is frequently observed in the stomach and esophagus. It is understood that esophageal adenocarcinoma's precursor lesion, chronic gastroesophageal reflux disease (GERD), is what causes Barrett's esophagus (BE), an acquired condition. Recently, Bile acids (BAs), which are one of the compositions of gastric and duodenal contents, have been confirmed that it led to the occurrence and development of BE and gastric intestinal metaplasia (GIM). The objective of the current review is to discuss the mechanism of IM induced by bile acids. This review serves as a foundation for further research aimed at improving the way BE and GIM are currently managed.

Recent advances in understanding the molecular mechanisms of cholestatic pruritus: A review

Cholestasis, a condition characterized by an abnormal decrease in bile flow, is accompanied by various symptoms such as pruritus. Although cholestatic pruritus is a prominent condition, its precise mechanisms have largely been elusive. Recently, advancements have been made for understanding the etiology and pathogenesis of cholestatic pruritus. The current review therefore focuses on summarizing the overall progress made in the elucidation of its molecular mechanisms. We have reviewed the available animal models on cholestasis to compare the differences between them, characterized potential pruritogens involved in cholestatic pruritus, and have summarized the receptor and ion channels implicated in the condition. Finally, we have discussed the available treatment options for alleviation of cholestatic pruritus. As our understanding of the mechanisms of cholestatic pruritus deepens, novel strategies to cure this condition are awaited.

[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.

Chemoprevention of colorectal cancer with ursodeoxycholic acid: pro

Colorectal cancer is the third and second most common cancer among men and women, respectively, in France. Interest in the chemoprevention of colorectal cancer has increased over the last two decades. Experimental data strongly suggest that ursodeoxycholic acid (UDCA) may have chemopreventative actions in colorectal cancer. UDCA is able to inhibit tumor development in azoxymethane and in dextran-related colitis models. In high-risk populations such as subjects with previous colorectal adenoma removal or inflammatory bowel disease, five out of 10 published studies suggested beneficial effects with UDCA on colonic carcinogenesis. In the azoxymethane model, UDCA inhibited tumor development by counteracting the tumor-promoting effects of secondary bile acids such as deoxycholic acid (DCA). The opposing effects of UDCA and DCA on lipid raft composition may be central to their effects on colonic tumorigenesis. Differential effects of DCA and UDCA on growth factor and inflammatory signals involved in colorectal carcinogenesis, such as epidermal growth factor receptor (EGFR) signaling and COX-2 expression, very likely mediate their opposing effects on colonic tumor promotion and tumor inhibition, respectively.

Primary biliary cirrhosis and bile acids

The dihydroxylated bile acid ursodeoxycholic acid (UDCA) has now been regarded for 20 years as the standard treatment for primary biliary cirrhosis (PBC), a chronic cholestatic immune-mediated condition marked by progressive destruction of small intrahepatic bile ducts, impaired biliary secretion, hepatocellular retention of toxic endogenous bile acids and, ultimately, the development of fibrosis leading to cirrhosis that commonly requires liver transplantation. At first sight, it seems intriguing that a bile acid could be considered for use as a therapeutic agent in a bile-acid secretion disorder. Yet, in addition to its inherently greater hydrophilic nature and competitive effect on endogenous bileacid recycling, UDCA has indeed been demonstrated to be a potent post-transcriptional secretagogue as well as a potential anti-inflammatory and anti-apoptotic agent. While the combined glucocorticoid receptor/pregnane X receptor (PXR) agonist budesonide, in combinaison with UDCA, has been shown to exert additional beneficial effects in PBC, significant progress in understanding the regulatory mechanisms involved in bile-acid homeostasis has led to the identification of nuclear [farnesoid X receptor (FXR), PXR, peroxisome proliferator-activated receptor alpha (PPARα)] and membrane (the membrane G protein-coupled bile acid receptor TGR5) receptors as critical pharmacological targets for future therapeutic approaches. Encouraging data from recent experimental and phase-II studies tend to confirm that the FXR agonist obeticholic acid and the PPARα agonists bezafibrate and fenofibrate may be used as add-on therapies in PBC patients with inadequate responses to UDCA or even as alternative first-line agents. These results could mark the beginning of a new therapeutic era for PBC.

Impact of the composition of gastric reflux bile acids on Barrett's oesophagus

BACKGROUND

The effect of the composition of reflux bile acids, especially the ratio of hydrophobic to hydrophilic ones, on the development of Barrett's oesophagus has not been fully investigated in human studies.

AIMS

To evaluate the influence of the bile acid composition of gastric juice on Barrett's oesophagus, a prospective study was designed.

METHODS

Fifty patients with and 100 patients without Barrett's oesophagus were enrolled. For all enrolled patients, gastric juice was collected by the endoscopic procedure for bile acid analysis. The ratio of hydrophobic to hydrophilic bile acids (bile hydrophobicity ratio, BHR) was calculated from 6 kinds of bile acids analysed in gastric juice. The relationship between the ratio and clinico-pathological factors of Barrett's oesophagus was investigated.

RESULTS

The mean of BHR of patients with Barrett's oesophagus was significantly higher than that of patients without Barrett's oesophagus (0.26 ± 0.05 vs. 0.08 ± 0.02, p<0.05). In multivariate analysis, a high BHR value was a predictor for the presence of Barrett's oesophagus (OR 5.74, p<0.001). In patients with Barrett's oesophagus, the BHR correlated with COX-2 protein expression and with accelerated cellular proliferation.

CONCLUSIONS

Patients with Barrett's oesophagus had a higher BHR in the gastric juice than those without.

Ursodeoxycholic acid and chemoprevention of colorectal cancer

Colorectal cancer is respectively the third and second most common cancer among men and women in France. Interest in chemoprevention for colorectal cancer has increased over the last two decades. Beside non-steroidal anti-inflammatory drugs, ursodeoxycholic acid (UDCA) may have chemopreventive action in colorectal cancer with a likely better tolerance. In high-risk populations such as patients with inflammatory bowel disease or prior colorectal adenoma or carcinoma, retrospective and prospective studies have suggested a beneficial effect of UDCA. In azoxymethane model, UDCA inhibits tumor development by countering the tumor-promoting effects of secondary bile acids, such as deoxycholic acid (DCA). The opposing effects of UDCA and DCA on lipid raft composition may be central to their effects on colonic tumorigenesis. Differential effects of DCA and UDCA on growth factor and inflammatory signals involved in colorectal carcinogenesis, such as epidermal growth factor receptors (EGFR) signaling and Cox-2 expression, likely mediate their opposing effects on colonic tumor promotion and tumor inhibition, respectively.

Protective effects of glycoursodeoxycholic acid in Barrett's esophagus cells

Barrett's esophagus (BE) is a premalignant condition associated with the development of esophageal adenocarcinoma (EAC). Previous studies have implicated hydrophobic bile acids and gastric acid in BE and EAC pathogenesis. In this study, we tested the hypothesis that DNA damage, cytotoxicity and oxidative stress induced by bile acids and gastric acid can be attenuated by the cytoprotective, hydrophilic bile acid glycoursodeoxycholic acid (GUDCA). Non-dysplastic BE cells were exposed for 10 min to pH 4 and/or bile acid cocktail or to pH 4 and a modified cocktail consisting of a mixture of bile acids and GUDCA. DNA damage was evaluated by the comet assay; cell viability and proliferation were measured by trypan blue staining and the MTS assay; reactive oxygen species (ROS) were measured using hydroethidium staining; oxidative DNA/RNA damage was detected by immunostaining with antibody against 8-OH-dG; thiol levels were measured by 5-chloromethylfluorescein diacetate (CMFDA) staining; and the expression of antioxidant proteins was evaluated by western blotting. DNA damage and oxidative stress were significantly increased, while thiol levels were decreased in BE cells treated with pH 4 and bile acid cocktail compared with cells treated with pH 4 alone or untreated cells. Bile acids and low pH also significantly decreased cell proliferation. Expression of the antioxidant enzymes, MnSOD and CuZnSOD, was elevated in the cells treated with bile acids and low pH. When GUDCA was included in the medium, all these effects of pH 4 and bile acids were markedly reduced. In conclusion, treatment of BE cells with acidified medium and a bile acid cocktail at physiologically relevant concentrations induces DNA damage, cytotoxicity, and ROS. The cytoprotective bile acid, GUDCA, inhibits these deleterious effects by inhibiting oxidative stress.

Ursodeoxycholic acid in primary biliary cirrhosis improves glutathione status but fails to reduce lipid peroxidation

BACKGROUND

Ursodeoxycholic acid (UDCA) may slow progression in primary biliary cirrhosis (PBC), but its effect on survival is controversial. We have previously demonstrated that oxidant stress, with severely depressed plasma glutathione, is a feature of untreated PBC; this study examines the effect of UDCA on lipid peroxidation, antioxidant status and associated processes.

PATIENTS AND METHODS

Markers of lipid peroxidation, antioxidant status, hepatic fibrogenesis, inflammation, cholestasis and synthetic function were measured at 0, 3, 6, 9 and 12 months in blood and urine from 35 PBC patients receiving UDCA.

RESULTS

Plasma glutathione, reflecting intrahepatic levels, climbed steadily on UDCA; although still subnormal, the median value at 12 months was 2.4-fold higher than the untreated level. Liver enzyme markers and C-reactive protein also improved, whilst PIIINP improved steadily, but the change did not attain statistical significance. Serum bilirubin remained unchanged and total antioxidant capacity, albumin and vitamin E decreased after 12 months' UDCA treatment. 8-Isoprostane increased and malondialdehyde was unchanged.

CONCLUSIONS

UDCA treatment partially corrected plasma glutathione status and some other biomarkers greatly improved, but lipid peroxidation was not reduced. UDCA may, therefore, require supplementation with glutathione precursors and/or antioxidant cocktails to reduce oxidant stress and thus delay disease progression to cirrhosis.

Drug insight: Mechanisms and sites of action of ursodeoxycholic acid in cholestasis

Ursodeoxycholic acid (UDCA) exerts anticholestatic effects in various cholestatic disorders. Several potential mechanisms and sites of action of UDCA have been unraveled in clinical and experimental studies, which could explain its beneficial effects. The relative contribution of these mechanisms to the anticholestatic action of UDCA depends on the type and stage of the cholestatic injury. In early-stage primary biliary cirrhosis and primary sclerosing cholangitis, protection of injured cholangiocytes against the toxic effects of bile acids might prevail. Stimulation of impaired hepatocellular secretion by mainly post-transcriptional mechanisms, including stimulation of synthesis, targeting and apical membrane insertion of key transporters, seems to be relevant in more advanced cholestasis. In intrahepatic cholestasis of pregnancy, stimulation of impaired hepatocellular secretion could be crucial for rapid relief of pruritus and improvement of serum liver tests, as it is in some forms of drug-induced cholestasis. In cystic fibrosis, stimulation of cholangiocellular calcium-dependent secretion of chloride and bicarbonate ions could have a major impact. Inhibition of bile-acid-induced hepatocyte apoptosis can have a role in all states of cholestasis that are characterized by hepatocellular bile-acid retention. Different mechanisms of action could, therefore, contribute to the beneficial effect of UDCA under various cholestatic conditions.

Effects of a 3-mo consumption of short-chain fructo-oligosaccharides on parameters of colorectal carcinogenesis in patients with or without small or large colorectal adenomas

Intervention studies of colorectal adenoma recurrence have demonstrated the need for surrogate markers of the cancer risk. Short-chain fructo-oligosaccharides (sc-FOS) have protective actions on colon carcinogenesis in animal models. We investigated differences in biological markers between adenoma and adenoma-free subjects, before and after 3 mo of daily intake of 10 g sc-FOS, within a multicenter study. After a full colonoscopy, 3 groups were studied at baseline and after 3 mo: 26 subjects with small colorectal adenoma(s), 18 with large adenoma(s), and 30 with no adenoma. At baseline, the mean fecal butyrate concentration was significantly lower in the adenoma groups than in the adenoma-free group (12.01 +/- 5.08 vs. 17.28 +/- 7.34 mmol/g dry weight) but was significantly increased in that group after 3-mo ingestion of sc-FOS (15.7 +/- 8.0 mmol/g; P = 0.02). In subjects without adenoma, sc-FOS ingestion was associated with a decrease in fecal lithocholic acid (P = 0.02) and an increase in cholic acid (P = 0.02), chenodeoxycholic acid (P = 0.04), total primary bile acids (P = 0.03), and ursodeoxycholic acid (P = 0.05). Fecal pH, blood parameters, and crypt cell proliferation were not significantly modified by sc-FOS ingestion in either group. In subjects with and without adenoma, sc-FOS affects some aspects of the colonic environment, which may be involved in prevention of colorectal neoplasia.

Effect of colitis and ileoanal pouch on biliary enrichment of ursodeoxycholic acid in primary sclerosing cholangitis

In primary sclerosing cholangitis (PSC), biliary enrichment of ursodeoxycholic acid (UDCA) may represent the decisive factor for its presumable beneficial effect. Up to now it is not clear how colitis and colectomy with ileo-anal pouch affect the biliary enrichment of UDCA and the biliary bile acid composition. We determined the biliary bile acid composition in 63 patients with PSC including 7 patients with ileo-anal pouch, 31 patients with colitis, and 25 patients without colitis. No differences existed between patients with and those without colitis. In patients with colectomy and pouch at a UDCA dose of 17.7 +/- 1.6 mg/kg (n = 7), biliary UDCA represented 46.4 +/- 6.7% (mean +/- SD) of total bile acids. An increase in the dose in six pouch patients from 12.5 +/- 0.9 to 22.3 +/- 1.6 mg/kg led to a slight increase in biliary enrichment of UDCA, from 39.8 +/- 8.1 to 49.4 +/- 10.7%. In five of seven patients with ileo-anal pouch, biliary UDCA enrichment was within the normal range, and in two of seven it was permanently or intermittently abnormally low. During UDCA treatment, in pouch patients the biliary content of deoxycholic acid and lithocholic acid was reduced, whereas all other bile acids were unchanged. In a minority of patients with ileo-anal pouch, biliary enrichment of UDCA may be markedly reduced, whereas patients with colitis have a biliary UDCA enrichment not different from that of patient without colitis.

Gallbladder bile composition in patients with Crohn’s disease

AIM: To further elucidate the pathogenesis and mechanisms of the high risk of gallstone formation in Crohn’s disease.

METHODS: Gallbladder bile was obtained from patients with Crohn’s disease who were admitted for elective surgery (17 with ileal/ileocolonic disease and 7 with Crohn’s colitis). Fourteen gallstone patients served as controls. Duodenal bile was obtained from ten healthy subjects before and after the treatment with ursodeoxycholic acid. Bile was analyzed for biliary lipids, bile acids, bilirubin, crystals, and crystal detection time (CDT). Cholesterol saturation index was calculated.

RESULTS: The biliary concentration of bilirubin was about 50% higher in patients with Crohn’s disease than in patients with cholesterol gallstones. Ten of the patients with Crohn’s disease involving ileum and three of those with Crohn’s colitis had cholesterol saturated bile. Four patients with ileal disease and one of those with colonic disease displayed cholesterol crystals in their bile. About 1/3 of the patients with Crohn’s disease had a short CDT. Treatment of healthy subjects with ursodeoxycholic acid did not increase the concentration of bilirubin in duodenal bile. Several patients with Crohn’s disease, with or without ileal resection/disease had gallbladder bile supersaturated with cholesterol and short CDT and contained cholesterol crystals. The biliary concentration of bilirubin was also increased in patients with Crohn’s colitis probably not due to bile acid malabsorption.

CONCLUSION: Several factors may be of importance for the high risk of developing gallstones of both cholesterol and pigment types in patients with Crohn’s disease.

Effect of high-dose ursodeoxycholic acid on its biliary enrichment in primary sclerosing cholangitis

Ursodeoxycholic acid (UDCA) has beneficial effects in cholestatic liver diseases. In primary sclerosing cholangitis (PSC), there is evidence that high doses (+/- 20 mg/kg) of UDCA may be more effective than average doses. Biliary enrichment of UDCA at such high doses may represent the decisive factor for its beneficial effect. Up to now it is not clear how high-dose UDCA correlates with its biliary enrichment and whether bacterial degradation of large amounts of UDCA may lead to an increased bacterial formation of more toxic hydrophobic bile acids. We determined the biliary bile acid composition in 56 patients with PSC including 30 patients with repeat bile samples treated with various doses of UDCA. At a UDCA dose of 10-13 mg/kg/d (n = 18) biliary UDCA represented 43.1% + 0.3% (mean + SD) of total bile acids; at a UDCA dose of 14-17 mg/kg (n = 14), its biliary content increased to 46.9% + 0.3%, at 18-21 mg/kg (n = 34) to 55.9% + 0.2%, at 22-25 mg/kg (n = 12) to 58.6% + 2.3%, and at 26-32 mg/kg (n = 8) to 57.7% + 0.4%. During UDCA treatment, the biliary content of all other bile acids was unchanged or decreased. In conclusion, biliary enrichment of UDCA increases with increasing dose and reaches a plateau at 22-25 mg/kg. There was no increase of toxic hydrophobic bile acids. If biliary enrichment of UDCA represents the decisive factor for its clinical effect, it seems likely that UDCA doses of up to 22-25 mg/kg may be more effective than lower doses.

Enterohepatic cycling of bilirubin as a cause of 'black' pigment gallstones in adult life

In contrast to bile salts, which undergo a highly efficient enterohepatic circulation with multiple regulatory and physiologic functions, glucuronic acid conjugates of bilirubin are biliary excretory molecules that in health do not have a continuing biologic life. Intestinal absorptive cells are devoid of recapture transporters for bilirubin conjugates, and their large size and polarity prevent absorption by passive diffusion. However, unconjugated bilirubin, the beta-glucuronidase hydrolysis product of bilirubin glucuronides can be absorbed passively from any part of the small and large intestines. This can occur only if unconjugated bilirubin is kept in solution and does not undergo rapid bacterial reduction to form urobilinoids. Here we collect, and in some cases reinterpret, experimental and clinical evidence to show that in addition to the well-known occurrence in newborns, enterohepatic cycling of unconjugated bilirubin can reappear in adult life. This happens as a result of several common conditions, particularly associated with bile salt leakage from the small intestine, the most notable ileal dysfunction resulting from any medical or surgical cause. We propose that when present in excess, colonic bile salts solubilize unconjugated bilirubin, delay urobilinoid formation, prevent calcium complexing of unconjugated bilirubin and promote passive absorption of unconjugated bilirubin from the large intestine. Following uptake, reconjugation, and resecretion into bile, this source of 'hyperbilirubinbilia' may be the important pathophysiological risk factor for 'black' pigment gallstone formation in predisposed adult humans.

Ursodeoxycholic acid therapy and the risk of colorectal adenoma in patients with primary biliary cirrhosis: an observational study

Ursodeoxycholic acid (UDCA) is the first-line treatment for primary biliary cirrhosis (PBC). The long-term administration of UDCA might indirectly favor colon carcinogenesis by increasing the fecal excretion of secondary bile acids or, in contrast, it might inhibit colon carcinogenesis, as demonstrated in animal models. In patients with PBC, we examined the effect of prolonged UDCA administration on the prevalence and recurrence of colorectal adenoma and on the proliferation of colon epithelial cells. One hundred fourteen patients (103 women, 11 men; mean age, 55 years) with PBC, were enrolled in a colonoscopic surveillance program. The prevalence of colon adenoma was compared in patients already treated with UDCA (mean duration 46 months) at the time of colonoscopy (treated group, n = 52) and in patients undergoing colonoscopy just prior to treatment initiation (untreated group, n = 62). The recurrence of adenoma following removal (mean follow-up, 35 months) was compared between UDCA-treated patients and appropriate age- and gender-matched controls (2/1) selected from a cohort of 205 patients undergoing polypectomy. Epithelial cell proliferation was assessed using anti-Ki67 antibodies on colon biopsies from both treated and untreated patients. Treated and untreated patients displayed similar demographic characteristics. The prevalence of colorectal adenomas was 13% in the treated group versus 24% in the untreated group (P =.16). The colon epithelial cell proliferation index was significantly lower in treated patients than in untreated patients (P =.001). Following removal of the adenoma, the probability of recurrence was significantly lower in patients treated with UDCA than in controls (7% vs. 28% at 3 years, P =.04). In conclusion, this study suggests that, in patients with PBC, the prolonged administration of UDCA (1) is not associated with an increased prevalence of colorectal adenomas, and (2) significantly decreases the probability of colorectal adenoma recurrence following removal. These results are strengthened by the significant reduction in colon epithelial cell proliferation seen in patients treated with UDCA.

Intestinal absorption and biliary secretion of ursodeoxycholic acid and its taurine conjugate

BACKGROUND

Ursodeoxycholic acid (UDCA) and its taurine conjugate (TUDCA) exert a protective effect in cholestatic liver diseases. A greater hepatoprotective effect of TUDCA has been suggested. Absorption appears to be a limiting factor and up to now has not been studied in man.

METHODS

We studied absorption and biliary bile acid secretion and composition after administration of UDCA and TUDCA in patients who had complete extrahepatic biliary obstruction caused by pancreatic carcinoma but had no intestinal or liver disease. After 5 days of intact enterohepatic circulation eight patients with a percutaneous biliary-duodenal drainage received, during two study periods, 1000 mg (1916.9 micromol; mean 29.6 micromol kg(-1)) TUDCA and 750 mg (1910.4 micromol; mean 29.5 micromol kg(-1)) UDCA in random order. Each patient served as his own control.

RESULTS

After UDCA and TUDCA administration the biliary UDCA content increased to 55.2% and 54.6% of total bile acids, respectively (not significant). Biliary secretion of cholic and chenodeoxycholic acids remained unchanged whereas that of lithocholic acid increased slightly. A total of 64.6% of the orally administered TUDCA and 55.1% of the UDCA was absorbed (not significant). After TUDCA administration, biliary UDCA was preferentially (95.4%) taurine-conjugated whereas after UDCA administration biliary UDCA was mainly (79.8%) glycine-conjugated.

CONCLUSIONS

After oral administration of TUDCA and UDCA, no significant differences in their absorption and in biliary bile acid secretion exist. Whether biliary enrichment with taurine conjugates of UDCA instead of glycine conjugates offers advantages in the treatment of cholestatic liver disease is unclear at present.

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.

Chronic cholestatic diseases

Chronic cholestatic diseases, whether occurring in infancy, childhood or adulthood, are characterized by defective bile acid transport from the liver to the intestine, which is caused by primary damage to the biliary epithelium in most cases. In this article, approaches to diagnosis and management of the main specific disorders are provided and some of the recent developments in this field are discussed. Major advances in the understanding of the cellular and molecular physiology of bile secretion have led to identification of genetic defects responsible for the different types of progressive familial intrahepatic cholestasis (PFIC). The potential role of the genes involved in PFIC in some adult cholestatic disorders remains to be determined. The majority of adult patients with chronic cholestasis have primary biliary cirrhosis (PBC) or primary sclerosing cholangitis (PSC). Recently, variant forms of PBC have been described. The term autoimmune cholangitis is used to describe patients having chronic non-suppurative cholangitis with negative antimitochondrial antibodies (AMA) but positive antinuclear and/or antismooth muscle antibodies. Autoimmune cholangitis and AMA-positive PBC are quite similar in terms of clinical presentation, survival and response to ursodeoxycholic acid (UDCA) therapy. In contrast, autoimmune cholangitis must be distinguished from PBC-autoimmune hepatitis (AIH) overlap syndrome in which biochemical and histological characteristics of both PBC and AIH coexist. Combination of UDCA and corticosteroids is required in most patients with overlap syndrome to obtain a complete clinical and biochemical response. Long-term UDCA treatment improves survival without liver transplantation in PBC patients. Among the putative mechanisms of the beneficial effects of UDCA, description of anti-apoptotic properties and effect on endotoxin disposal in biliary cells have provided new insights. In patients with incomplete response to UDCA, combination of UDCA with antiinflammatory or immunosuppressive drugs is under evaluation. Variant forms of PSC have also been described, including PSC-AIH overlap syndrome, especially in children or young adults, and small-duct PSC, which is characterized by normal cholangiogram in patients having chronic cholestasis, histologic features compatible with PSC and inflammatory bowel disease. Development of cholangiocarcinoma (CC) is a major feature of PSC, occurring in 10-15% of patients. Early diagnosis of CC is a difficult challenge, although positron emission tomography seems a promising tool. Unlike PBC, effective medical therapy is not yet available in PSC, reflecting the lack of knowledge about the exact pathogenesis of the disease. Currently, liver transplantation is the only effective therapy for patients with advanced disease, although recurrence of PSC in the graft may occur.

Effect of ursodeoxycholic acid administration in patients with acute viral hepatitis: a pilot study

BACKGROUND

Ursodeoxycholic acid (UDCA) is able to improve biochemical markers of cholestasis, with a parallel decrease in transaminases, in various cholestatic liver diseases.

AIM

To evaluate the effects of UDCA administration on acute viral hepatitis-related cholestasis and the course of acute viral hepatitis.

METHODS

Seventy-nine consecutive patients with acute viral hepatitis (HBV: 43, HCV: 11, HAV: 15, HEV: 3, Non A-E: 7) were randomized to receive either UDCA for 3 weeks or no treatment. Liver biochemistry and serum bile acid determinations were run at weekly intervals.

RESULTS

No significant differences were observed in mean percentage decreases in transaminases between treated and untreated patients. By contrast, cholestatic indexes decreased significantly more quickly in patients treated with UDCA than in controls, and this effect was more evident in patients with increasing alanine transaminase levels at admission. After a peak at the end of the first week of therapy, serum levels of conjugated ursodeoxycholic acid (CUDCA) showed a gradual decrease. Conjugated cholic acid (CCA) and chenodeoxycholic acid (CCDCA) showed a progressive decrease with the resolution of viral hepatitis, but no influence of UDCA administration was observed.

CONCLUSIONS

Our study demonstrates that UDCA significantly improves cholestatic indices in patients with acute viral hepatitis, but this effect does not seem to affect the course of the illness.

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.

The effect of bile salts and calcium on isolated rat liver mitochondria

Intact mitochondria were incubated with and without calcium in solutions of chenodeoxycholate, ursodeoxycholate, or their conjugates. Glutamate dehydrogenase, protein and phospholipid release were measured. Alterations in membrane and organelle structure were investigated by electron paramagnetic resonance spectroscopy. Chenodeoxycholate enhanced enzyme liberation, solubilized protein and phospholipid, and increased protein spin label mobility and the polarity of the hydrophobic membrane interior, whereas ursodeoxycholate and its conjugates did not damage mitochondria. Preincubation with ursodeoxycholate or its conjugate tauroursodeoxycholate for 20 min partially prevented damage by chenodeoxycholate. Extended preincubation even with 1 mM ursodeoxycholate could no longer prevent structural damage. Calcium (from 0.01 mM upward) augmented the damaging effect of chenodeoxycholate (0.15-0.5 mM). The combined action of 0.01 mM calcium and 0.15 mM chenodeoxycholate was reversed by ursodeoxycholate only, not by its conjugates tauroursodeoxycholate and glycoursodeoxycholate. In conclusion, ursodeoxycholate partially prevents chenodeoxycholate-induced glutamate dehydrogenase release from liver cell mitochondria by membrane stabilization. This holds for shorter times and at concentrations below 0.5 mM only, indicating that the different constitution of protein-rich mitochondrial membranes does not allow optimal stabilization such as has been seen in phospholipid- and cholesterol-rich hepatocyte cell membranes, investigated previously.

Mechanism of hepatoprotective action of bile salts in liver disease

Ursodeoxycholic acid (UDCA) improves liver enzymes and in many instances liver histology in cholestatic liver diseases such as primary biliary cirrhosis and primary sclerosing cholangitis. Besides classic cholestatic diseases, UDCA also improves liver biochemistry in alcoholic liver disease and in chronic viral hepatitis C. The main target of UDCA treatment, however, is cholestasis, and consequently the mechanisms responsible for the beneficial effects in these diseases are of interest, and are discussed in detail in this article.

Tauroursodeoxycholate and S-adenosyl-L-methionine exert an additive ameliorating effect on taurolithocholate-induced cholestasis: a study in isolated rat hepatocyte couplets

The monohydroxy bile acid, taurolithocholate (TLC), causes cholestasis in vivo and in isolated perfused livers. It is also cholestatic in vitro and, in this study using isolated rat hepatocyte couplets, causes a reduction of the accumulation of (fluorescent) bile acid in the canalicular vacuoles (cVA) of this polarized cell preparation. The hepatoprotective bile acid, tauroursodeoxycholate (TUDCA), partially protects against the action of TLC when added at the same time. It also partially reverses the cholestatic effect if added after the cells have been exposed to TLC. A second hepatoprotective compound, S-adenosyl-L-methionine (SAMe) also not only partially protects against the action of TLC when added at the same time, but it too is able to partially reverse the cholestatic effect. Neither hepatoprotective agent is fully effective alone, but their effects are additive. In combination, a full restoration of cVA is observed in moderate cholestasis, but not in severe cholestasis. We discuss briefly some possible mechanisms involved in the additive mode of action of both hepatoprotective compounds. In summary, we show for the first time that SAMe and TUDCA can exert an additive effect in the amelioration of TLC-induced cholestasis in isolated rat hepatocyte couplets. This finding may be of possible clinical relevance.

Ursodeoxycholic acid and cholesterol induce enterohepatic cycling of bilirubin in rodents

BACKGROUND & AIMS

Oral administration of ursodeoxycholic acid (UDCA) and cholesterol causes bile salt malabsorption; the former by competition for and the latter by down-regulation of ileal bile acid transporters. Because ileectomy in rats induces enterohepatic cycling of bilirubin, the hypothesis that dietary steroids might have the same effect was tested.

METHODS

Male inbred C57L/J mice and Sprague-Dawley rats were fed low doses of UDCA, chenodeoxycholic acid (CDCA), or cholesterol added to laboratory chow with simultaneous chow-fed controls. After 1 week (mice) or 2 weeks (rats), indices of bile salt malabsorption and enterohepatic cycling of bilirubin were measured, including bilirubin secretion rates into bile, serum and intestinal bilirubin and bile salt levels, and urobilinogen levels in cecum, large intestine, and feces.

RESULTS

Dietary UDCA and cholesterol, but not CDCA, significantly increased bilirubin secretion rates into bile. In UDCA-fed mice, gallbladder biles contained increased levels of bilirubin conjugates and unconjugated bilirubin, and in 60%, granules of amorphous calcium bilirubinate precipitated. Dietary cholesterol and bile acids, particularly UDCA, increased cecal bile salt levels, unconjugated bilirubin and urobilinogen concentrations, and decreased fecal bilirubin outputs, consistent with colonic absorption.

CONCLUSIONS

By causing bile salt malabsorption, dietary UDCA and cholesterol induce enterohepatic cycling of bilirubin.

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.

Intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a disease of the third trimester of pregnancy involving pruritus and elevated bile acid levels. Its pathogenesis likely involves a genetic hypersensitivity to estrogen. Once thought to be benign for both mother and fetus, ICP has been associated with increased rates of fetal morbidity and mortality and an increased risk of maternal coagulopathy. Optimal obstetric management includes delivery after establishment of fetal lung maturity. Many treatments have been proposed for the maternal medical management of ICP, none of which is ideal.

Vitamin E reduces oxidant injury to mitochondria and the hepatotoxicity of taurochenodeoxycholic acid in the rat

BACKGROUND & AIMS

Hydrophobic bile acids have been implicated in the pathogenesis of cholestatic liver injury. The hypothesis that hydrophobic bile acid toxicity is mediated by oxidant stress in an in vivo rat model was tested in this study.

METHODS

A dose-response study of bolus intravenous (i.v.) taurochenodeoxycholic acid (TCDC) in rats was conducted. Rats were then pretreated with parenteral alpha-tocopherol, and its effect on i.v. TCDC toxicity was evaluated by liver blood tests and by assessing mitochondrial lipid peroxidation.

RESULTS

Four hours after an i.v. bolus of TCDC (10 mumol/100 g weight), serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels peaked, hepatic mitochondria showed evidence of increased lipid peroxidation, and serum bile acid analysis was consistent with a cholestatic injury. Liver histology at 4 hours showed hepatocellular necrosis and swelling and mild portal tract inflammation. Treatment with parenteral alpha-tocopherol was associated with a 60%-70% reduction in AST and ALT levels, improved histology, and a 60% reduction in mitochondrial lipid peroxidation in rats receiving TCDC.

CONCLUSIONS

These data show that hepatocyte injury and oxidant damage to mitochondria caused by i.v. TCDC can be significantly reduced by pretreatment with the antioxidant vitamin E. These in vivo findings support the role for oxidant stress in the pathogenesis of bile acid hepatic toxicity.

The Nordic multicenter double-blind randomized controlled trial of prophylactic ursodeoxycholic acid in liver transplant patients

BACKGROUND

Prophylactic treatment with ursodeoxycholic acid (UDCA) has been reported to reduce the incidence of acute rejection after liver transplantation compared with historical controls. We investigated this in a prospective, randomized, placebo-controlled multicenter study.

METHODS

Fifty-four liver transplant patients were allocated to the UDCA treatment group (15 mg/kg/day), and 48 patients were allocated to the placebo group. Trial medicine was started on the first postoperative day and was given for 3 months. Follow-up was for 12 months. Treatment was stratified for adults with chronic liver disease (n=77), adults with acute liver failure (n=10), and children (n=15).

RESULTS

The frequency of patients with acute rejection was 65% in the UDCA treatment group and 68% in the placebo group. The frequency of steroid-resistant rejection was similar in both groups. The probability of acute rejection, analyzed according to the intention-to-treat policy with Kaplan-Meier analysis, was similar in both treatment groups. No significant differences were found in patient survival and graft survival probabilities. For the biochemical markers of cholestasis, only gamma-glutamyltransferase was significantly improved after 2 months of UDCA treatment.

CONCLUSIONS

The initial optimistic report of a beneficial effect of prophylactic treatment with UDCA on acute rejection after liver transplantation was not confirmed in this controlled study.

Use of ursodeoxycholic acids in a dog with chronic hepatitis: effects on serum hepatic tests and endogenous bile acid composition

A dog with severe cholestasis secondary to chronic hepatitis was treated with ursodeoxycholic acid (UDCA) PO. After 2 weeks of daily treatment, the dog was more active and had an improved appetite. Monthly serum biochemical determinations and analysis of individual bile acid profiles documented improvement in hepatobiliary tests and a marked reduction in the concentrations of potentially hepatotoxic endogenous bile acids. These effects were maintained for approximately 6 months. The findings in this dog are similar to those reported for human patients treated with UDCA and provide preliminary evidence in support of its continued evaluation in the treatment of cholestatic liver disease in the dog.

Ileal absorption of bile acids in patients with chronic cholestasis: SeHCAT test results and effect of ursodeoxycholic acid (UDCA)

The effect of cholestasis on ileal bile acid absorption is controversial in animal models (up- or down-regulation) and unknown in humans. We therefore studied values of the selena homotaurocholic acid (SeHCAT) test before and after long-term administration (>3 months, 13-15 mg/kg/day) of ursodeoxycholic acid (UDCA) in 27 patients with chronic cholestatic liver diseases (24 women, 3 men; mean age, 50 years; 24 primary biliary cirrhosis, 2 secondary biliary cirrhosis, 2 others). The control group consisted of 14 healthy volunteers. Seven-day SeHCAT percentage retention was identical in the 12 untreated cholestatic patients (serum bilirubin, 75+/-42 micromol/L, alkaline phosphatase, 4.2+/-1.0 N; mean+/-SEM) and in the control group (43.6+/-2.9 and 43.8+/-4.2%, respectively). In the 22 patients treated by UDCA for 38+/-8 months, SeHCAT percentage retention was 20.3+/-3.0%. In the seven patients with the SeHCAT test done before and after UDCA treatment (16+/-5 months), SeHCAT percentage retention decreased significantly under UDCA therapy (42.0+/-4.4 vs 19.4+/-4.1%; P < 0.02). We conclude that, in patients with chronic cholestasis (1) SeHCAT percentage retention is not altered-taken together with the known defect of biliary excretion, this lack of increase in SeHCAT percentage retention argues against up-regulation of bile acid ileal transport; and (2) UDCA treatment induces a decrease in the SeHCAT percentage retention-this effect may be related primarily to a decreased bile acid ileal absorption.

Single or multiple dose ursodeoxycholic acid for cholestatic liver disease: biliary enrichment and biochemical response

BACKGROUND

Ursodeoxycholic acid (UDCA) improves liver biochemistry in primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Since UDCA acts partly by reducing the intestinal absorption of hydrophobic endogenous bile salts and is poorly absorbed from the intestine, a multiple dose regimen has been advocated. Single dose treatment, on the other hand, may improve compliance.

AIM

The effects of a single or multiple dose regimen on liver enzymes and serum and biliary bile salts composition were evaluated.

METHODS

Twenty-seven patients (19 PSC, 8 PBC), most with early stage disease, received UDCA (10 mg kg-1 day-1) in a single dose at bed time (n = 13) or in three divided gifts with meals (n = 14) over 3 months. Five patients had both treatment regimens in random order with a 1-month wash-out period in between.

RESULTS

Liver biochemistry equally improved in both groups. Biliary enrichment (% UDCA of total bile salts, mean +/- SEM) was 40.1 +/- 2.4 in the single dose group vs 40.8 +/- 2.8 in the multiple dose group (p = NS) and was positively correlated with biochemical improvement (AP: r = 0.47, p = 0.02; GGT: r = 0.58, p = 0.002; ASAT: r = 0.67, p = 0.002; ALAT: r = 0.52, p = 0.01). Biochemical improvement was not correlated with the concentration or %UDCA in serum. Patients participating in the cross-over design had comparable biochemical response and biliary %UDCA during both regimens.

CONCLUSION

Single and multiple dose UDCA have similar effects on liver biochemistry and biliary enrichment in cholestatic liver disease. Biochemical improvement appears to be related to biliary (but not serum) enrichment with UDCA.

Effects of oral ursodeoxycholic acid in healthy cats on clinicopathological parameters, serum bile acids and light microscopic and ultrastructural features of the liver

A blind, placebo-controlled study evaluated the effects of ursodeoxycholic acid (UDCA) given orally, at a dose of 15 mg kg-1 per day for eight weeks, on the physical condition, haematological and serum biochemical profiles, urinalysis, total serum bile acids (TSBA) and hepatic histology of four healthy cats. There were no clinically important significant differences between the groups or within the treatment groups in clinicopathological parameters. TSBA concentrations or histology. A significant lower concentration/proportion of taurochenodeoxycholic acid was observed in the treated cats (P = 0.05). Only one treated cat accumulated measurable quantities of UDCA, and the compound appeared to be non-toxic. It did not increase the concentration of TSBA, and accumulated minimally in the serum. It should be investigated for therapeutic use in cats with hepatobiliary disease.

Metabolism of orally administered tauroursodeoxycholic acid in patients with primary biliary cirrhosis

The metabolism of tauroursodeoxycholic acid orally administered and its effects on the bile acid pool of patients with asymptomatic/mildly symptomatic primary biliary cirrhosis is described. Patients were randomly assigned 500, 1000, or 1500 mg/day of tauroursodeoxycholate for six months. Biliary and serum bile acids were measured before and during treatment by gas chromatography-mass spectrometry and by high performance liquid chromatography. During tauroursodeoxycholate administration, the proportion of total ursodeoxycholate in bile reached mean (SEM) 34.4 (4.5)%, 32.8 (2.8)%, and 41.6 (3.0)% with doses of 500, 1000, and 1500 mg/day, respectively. Significant decreases in the proportions of chenodeoxycholate and cholate resulted. The glycine/taurine ratio of the biliary bile acid pool decreased from 1.9 at baseline, to 1.1 with the highest dose. Ursodeoxycholate in bile was conjugated with glycine and taurine, indicating that tauroursodeoxycholate undergoes significant deconjugation and reconjugation during its enterohepatic recycling. The proportion of lithocholate in bile remained unchanged. Fasting serum conjugated ursodeoxycholate concentration positively correlated with the tauroursodeoxycholate dose, and the increased proportion of ursodeoxycholate was accompanied by substantial decreases in the endogenous bile acids. Compared with previously published data for ursodeoxycholic acid therapy, these findings indicate that the shift toward a more hydrophilic bile acid pool is greater and potentially more favourable with tauroursodeoxycholate, and this is because of the reduced intestinal biotransformation of tauroursodeoxycholate.

Effects of chenodeoxycholic and ursodeoxycholic acids on interferon-gamma production by peripheral blood mononuclear cells from patients with primary biliary cirrhosis

Ursodeoxycholic acid (UDCA) administration can obtain marked improvement of primary biliary cirrhosis (PBC). Recently, UDCA has been demonstrated to have a direct effect on immunological reactions in patients with PBC in that the aberrant expression of major histocompatibility complex (MHC) class I molecules was markedly reduced after UDCA treatment. To understand the immunological effect of UDCA, we analyzed interferon (IFN)-gamma production in peripheral blood mononuclear cells (PBMCs) from 29 patients with PBC treated with UDCA (group 1), 19 patients with PBC who were not treated with UDCA (group 2), 11 healthy subjects (group 3), and 12 patients with chronic viral hepatitis (group 4). IFN-gamma production was investigated because the excess production of this cytokine is associated with the aberrant expression of MHC molecules. Whereas IFN-gamma production in the patients in group 2 was significantly increased, the level of production in group 1 was similar to that in the control groups (groups 3 and 4). There was significant improvement in IFN-gamma production in 6 patients with PBC after UDCA treatment. The effect of UDCA and chenodeoxycholic acid (CDCA) on IFN-gamma production in PBMCs from 12 normal subjects was also analyzed. IFN-gamma was produced dose-dependently according to concentrations of CDCA ranging from 0.1 to 10 microM, but the increase in production was markedly suppressed by the addition of UDCA. We conclude that low doses of CDCA enhance IFN-gamma production and may therefore lead to the aberrant hepatic expression of MHC molecules, and that the increase in IFN-gamma production is suppressed by UDCA.

The site-specific delivery of ursodeoxycholic acid to the rat colon by sulfate conjugation

BACKGROUND & AIMS

Because ursodeoxycholate has been shown to act as a tumor-suppressive agent in the colon, the absorption and metabolism of its sulfate conjugates were examined in rats to show that sulfation would facilitate the site-specific delivery of ursodeoxycholate to the colon.

METHODS

Bile acids were measured in intestinal contents, feces, urine, plasma, and liver tissue after oral administration of ursodeoxycholate and its C-3, C-7, and C-3,7 sulfate derivatives.

RESULTS

Ursodeoxycholate was found in the jejunum after administration of all bile acids, but the mass was greatest for ursodeoxycholic acid administration. In the colon, lithocholic acid, normally found in negligible amounts, became the major bile acid after ursodeoxycholate administration. In contrast, reductions in mass and proportions of lithocholate and deoxycholate occurred after administering the C-7 sulfates. The fecal lithocholate/deoxycholate ratio, a risk marker for colon cancer, increased markedly after administration of ursodeoxycholate and its C-3 sulfate, but did not change after administering the C-7 sulfates. Unlike ursodeoxycholate or its C-3 sulfate, which increased liver concentrations of lithocholate and ursodeoxycholate, the C-7 sulfates had the opposite effect, which was consistent with poor absorption.

CONCLUSIONS

Sulfation of ursodeoxycholate, specifically at the C-7 position, protects the molecule from bacterial degradation and inhibits its intestinal absorption, thereby facilitating delivery to the colon.

Ursodeoxycholic acid therapy of chronic cholestatic conditions in adults and children

Cholestasis can be defined as the manifestation of defective bile acid transport from the liver to the intestine. Most chronic cholestatic conditions can progress towards cirrhosis. At this stage, liver transplantation is the treatment of choice. Most of the drugs so far evaluated show some degree of efficacy but have major side effects. Given that ursodeoxycholic acid (UDCA) has no apparent toxicity in humans, it was postulated that long-term treatment with this drug might displace endogenous bile acids and thus reverse their suspected toxicity. We demonstrated that long-term UDCA therapy slows the progression of primary biliary cirrhosis and reduces the need for liver transplantation. In this review, we give the rationale for the use of UDCA in cholestasis and discuss its possible mechanisms of action. We also give an overview of current data on UDCA therapy of chronic cholestatic disorders in adults and children.

Bile acids in the diagnosis, pathology, and therapy of hepatobiliary diseases

Bile acids are normally confined in the enterohepatic circulation in which they play an important role in bile formation, biliary lipid excretion, and intestinal lipid absorption. In hepatobiliary diseases, bile acids escape the confinement of the enterohepatic circulation, allowing the measurement of the serum total bile acid concentration as a diagnostic indicator. Accumulation of certain bile acids within the hepatocyte, amplified as a consequence of cholestatic hepatobiliary disease, probably enhances cytotoxicity and leads to secondary pathology. Ursodeoxycholate, a bile acid with atypical physiological effects, may be useful in the treatment of various long-term cholestatic hepatobiliary diseases. Presently, most of the information on the toxicity and therapeutic usefulness of bile acids are based on studies in humans and experimental animals. Further studies, both basic and clinical, are needed to determine the pathologic as well as the therapeutic effects of bile acids in domestic animals.

Serum conjugated bile acid profile during intrahepatic cholestasis of pregnancy

BACKGROUND/AIMS

Intrahepatic cholestasis of pregnancy is a specific liver disease of pregnancy of unknown cause. The serum bile acid profile has not been clearly described in this disease and the aim of this study was to investigate the serum conjugated bile acid profile.

METHODS

Thirteen patients with intrahepatic cholestasis of pregnancy were studied. Ten patients had been treated with natural progestatin before the onset of pruritus. The glyco- and tauroconjugated bile acids were quantified by high-performance liquid chromatography and direct spectrometric detection at 199 nm.

RESULTS

There was no difference between total bile acid concentrations measured by high-performance liquid chromatography (43.5 +/- 22.6 microM, mean +/- S.D.) or by an enzymatic procedure (43.4 +/- 24.6 microM), indicating a low concentration of free bile acids. Primary bile acids represented 88% of total bile acids, i.e. 72.7% for cholic acid and 15.3% for chenodeoxycholic acid. For both cholic and chenodeoxycholic acids glyco- and tauroconjugates were equivalent. Secondary bile acids represented 11.3% of total bile acids. Ursodeoxycholic acid was identified at very low concentrations in only three samples.

CONCLUSIONS

We conclude that in intrahepatic cholestasis of pregnancy primary bile acids are very predominant.

Ursodeoxycholate conjugates protect against disruption of cholesterol-rich membranes by bile salts

BACKGROUND/AIMS

Ursodeoxycholic acid attenuates hepatocellular injury in cholestatic disorders, possibly by counteracting membrane disruptive effects of endogenous bile salts. The possible physicochemical basis of this protective effect was explored by using model membranes composed of egg phosphatidylcholine and cholesterol.

METHODS

Large unilamellar vesicles containing trapped 3H inulin were prepared by extrusion and gel filtration. Vesicle disruption (release of trapped inulin) was quantified using rapid centrifugal ultrafiltration.

RESULTS

Disruption of membranes increased with bile salt concentration, hydrophobicity, and increasing ionic strength. Disruption decreased with a decreasing bile salt/phospholipid ratio or an increasing cholesterol/phospholipid ratio. Vesicle disruption by taurodeoxycholate (3 alpha, 12 alpha-dihydroxy-5 beta-cholanoyl taurine) was reduced in a concentration-dependent manner by addition of tauroursodeoxycholate (3 alpha,7 beta-dihydroxy-5 beta-cholanoyl taurine) (TUDC) when the cholesterol/phospholipid ratio was > or = 0.5, but TUDC was not protective at a cholesterol/phospholipid ratio < or = 0.2. Glycoursodeoxycholate (3 alpha,7 beta-dihydroxy-5 beta-cholanoyl glycine) was somewhat less protective than TUDC, and unconjugated ursodeoxycholate (3 alpha,7 beta-dihydroxy-5 beta-cholanoate) (UDC) had little effect. Taurine conjugates of several other hydrophilic bile salts were also protective, but protection was not strictly proportional to hydrophilicity.

CONCLUSIONS

Conjugates of UDC and other hydrophilic bile salts can reduce disruption of cholesterol-rich model membranes by more toxic bile salts via a purely physicochemical mechanism. UDC conjugates in vivo may protect the cholestatic liver by preventing bile salt disruption of the cholesterol-rich canalicular membrane.

A two year controlled trial examining the effectiveness of ursodeoxycholic acid in primary biliary cirrhosis

Forty-six patients with primary biliary cirrhosis from a single centre were studied in a randomized placebo-controlled trial to determine the effectiveness of ursodeoxycholic acid (UDCA) over a 2 year period. The two groups were well-matched at baseline. For each parameter, by calculating the difference between the median changes with time between the UDCA group and the placebo group, it was found that from entry, with respect to placebo, there were differences between median changes (MCD) favouring the UDCA group in bilirubin (MCD 5 mumol/L [95% confidence interval (CI) 1 to 12] at 1 year and 5 mumol/L (95% CI 1 to 9) at 2 years), alkaline phosphatase MCD 242 iu/L (95% CI 107 to 360) at 1 year and 268 iu/L (95% CI 146 to 424) at 2 years and aspartate aminotransferase MCD 26 iu/L (95% CI 12 to 41) at 1 year and 37 iu/L (95% CI 16 to 64) at 2 years. Within the UDCA group, there was long-term fall in alkaline phosphatase [median fall 116 iu/L (95% CI 93 to 378) at 2 years and aspartate aminotransferase [median fall 18 iu/L (95% CI 6 to 47) at 2 years; however, the major change in bilirubin was a modest rise over 2 years in the placebo group [median rise 2 mumol/L (95% CI 1 to 9)]. Changes in albumin, prothrombin ratio and immunoglobulins were generally minor and not significant.(ABSTRACT TRUNCATED AT 250 WORDS)