Effect of ursodeoxycholic acid administration on bile duct proliferation and cholestasis in bile duct ligated rat

Oral chronic toxicity study of geniposide in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Geniposide, the major active constituent of Fructus Gardeniae (FG), has been widely used to treat various diseases in China.

AIM OF THE STUDY

This chronic toxicity study was conducted to investigate the safety of geniposide.

MATERIALS AND METHODS

Geniposide was administered to Sprague-Dawley (SD) rats of both sexes by oral gavage at dosages of 25, 50, or 100mg/kg in a volume of 10mL/kg once daily for 26 weeks. Endpoints included clinical observations, food consumption, body weights, blood biochemistry, haematology, and histomorphological observations.

RESULTS

The administration of geniposide did not influence animal mortality, the general conditions of the animals, body weights or food consumption. After 4 weeks of administration, significant toxicity was not observed. However, in the 13th week of the toxicity study, a few haematological parameters and some relative organ weights of male rats in the 50 and 100mg/kg geniposide groups were significantly increased. The percentage of reticulocytes (Retic %) was significantly increased in male and female rats administered 100mg/kg geniposide. In addition, two female rats in the 100mg/kg geniposide group showed slight pathological changes in hepatic and renal tissues. Furthermore, in a chronic (26 weeks) toxicity study, differences were detected in alanine aminotransferase (ALT), aspartate aminotransferase (AST), sodium (Na⁺), potassium (K⁺), white blood cell (WBC), red blood cell (RBC), and haemoglobin (HGB) levels and the relative weights of the liver and spleen in male rats administered 100mg/kg geniposide. In addition, differences were detected in Retic % and the relative weights of the liver, thymus, and kidneys in female rats administered 100mg/kg geniposide. Urinalysis results from male and female rats in the 100mg/kg geniposide group revealed noticeable changes. The histopathological structures of hepatic and renal tissues in the high-dose geniposide group exhibited serious abnormalities and pigment deposition.

CONCLUSION

Geniposide affected serum biochemistry, urinalysis, and haematological parameters as well as relative organ weights. The treatment also caused noticeable pathological abnormalities in liver and kidney tissues. Therefore, administration of a high dose of geniposide (100mg/kg) for 26 weeks could induced obvious liver and kidney damage.

Characterization of a novel bile acid-based delivery platform for microencapsulated pancreatic β-cells

INTRODUCTION

In a recent study, we confirmed good chemical and physical compatibility of microencapsulated pancreatic β-cells using a novel formulation of low viscosity sodium alginate (LVSA), Poly-L-Ornithine (PLO), and the tertiary bile acid, ursodeoxycholic acid (UDCA). This study aimed to investigate the effect of UDCA on the morphology, swelling, stability, and size of these new microcapsules. It also aimed to evaluate cell viability in the microcapsules following UDCA addition.

MATERIALS AND METHODS

Microencapsulation was carried out using a Büchi-based system. Two (LVSA-PLO, control and LVSA-PLO-UDCA, test) pancreatic β-cells microcapsules were prepared at a constant ratio of 10:1:3, respectively. The microcapsules' morphology, cell viability, swelling characteristics, stability, mechanical strength, Zeta potential, and size analysis were examined. The cell contents in each microcapsule and the microencapsulation efficiency were also examined.

RESULTS

The addition of UDCA did not affect the microcapsules' morphology, stability, size, or the microencapsulation efficiency. However, UDCA enhanced cell viability in the microcapsules 24 h after microencapsulation (p < 0.01), reduced swelling (p < 0.05), reduced Zeta potential (- 73 ± 2 to - 54 ± 2 mV, p < 0.01), and increased mechanical strength of the microcapsules (p < 0.05) at the end of the 24-h experimental period.

DISCUSSION AND CONCLUSION

UDCA increased β-cell viability in the microcapsules without affecting the microcapsules' size, morphology, or stability. It also increased the microcapsules' resistance to swelling and optimized their mechanical strength. Our findings suggest potential benefits of the bile acid UDCA in β-cell microencapsulation.

Bile-acid-induced cell injury and protection

Several studies have characterized the cellular and molecular mechanisms of hepatocyte injury caused by the retention of hydrophobic bile acids (BAs) in cholestatic diseases. BAs may disrupt cell membranes through their detergent action on lipid components and can promote the generation of reactive oxygen species that, in turn, oxidatively modify lipids, proteins, and nucleic acids, and eventually cause hepatocyte necrosis and apoptosis. Several pathways are involved in triggering hepatocyte apoptosis. Toxic BAs can activate hepatocyte death receptors directly and induce oxidative damage, thereby causing mitochondrial dysfunction, and induce endoplasmic reticulum stress. When these compounds are taken up and accumulate inside biliary cells, they can also cause apoptosis. Regarding extrahepatic tissues, the accumulation of BAs in the systemic circulation may contribute to endothelial injury in the kidney and lungs. In gastrointestinal cells, BAs may behave as cancer promoters through an indirect mechanism involving oxidative stress and DNA damage, as well as acting as selection agents for apoptosis-resistant cells. The accumulation of BAs may have also deleterious effects on placental and fetal cells. However, other BAs, such as ursodeoxycholic acid, have been shown to modulate BA-induced injury in hepatocytes. The major beneficial effects of treatment with ursodeoxycholic acid are protection against cytotoxicity due to more toxic BAs; the stimulation of hepatobiliary secretion; antioxidant activity, due in part to an enhancement in glutathione levels; and the inhibition of liver cell apoptosis. Other natural BAs or their derivatives, such as cholyl-N-methylglycine or cholylsarcosine, have also aroused pharmacological interest owing to their protective properties.

Effect of ursodeoxycholic acid on liver function in children after successful surgery for biliary atresia

OBJECTIVES

Although ursodeoxycholic acid has been used to treat various cholestatic liver diseases in children, few data are available about its efficacy in biliary atresia. The aim of this study was to assess the effect of ursodeoxycholic acid treatment on liver function in children who underwent successful surgery for biliary atresia.

PATIENTS AND METHODS

We prospectively studied 16 children with biliary atresia who underwent successful portoenterostomies (postoperative conjugated bilirubin concentration: <34 micromol/L) and were treated with ursodeoxycholic acid for at least 18 months after surgery. Ursodeoxycholic acid treatment was then discontinued. Clinical and biological assessment was performed at the time of discontinuation of ursodeoxycholic acid treatment (T0), at follow-up (T1) and, if the clinical or biological status worsened, after resumption of ursodeoxycholic acid treatment (T2).

RESULTS

Ursodeoxycholic acid treatment was resumed in 13 cases. In 1 patient, jaundice recurred after ursodeoxycholic acid therapy was discontinued but abated after resumption of treatment. In 13 children, liver function worsened significantly when ursodeoxycholic acid was discontinued. T1 versus T0 concentrations expressed as multiples of the upper limit of the normal range (in parentheses) were as follows: alanine aminotransferase, 3.0 xN (0.8-7.0) vs 1.5 xN (0.5-5.4); gamma glutamyl transpeptidase, 8.0 xN (1.8-30.2) vs 4.2 xN (0.5-27.4); and aspartate aminotransferase, 1.7 xN (0.7-6.0) vs 1.3 xN (0.6-3.4). When ursodeoxycholic acid treatment was resumed, liver function had improved in all patients by T2. Concentrations of endogenous bile acids tended to be elevated at T1 (not significant) and were significantly decreased at T2.

CONCLUSION

Our study demonstrates the beneficial effect of ursodeoxycholic acid on liver function in children after successful surgery for biliary atresia.

Involvement of oxidative stress in the impairment in biliary secretory function induced by intraperitoneal administration of aluminum to rats

We have shown that aluminum (Al) induces cholestasis associated with multiple alterations in hepatocellular transporters involved in bile secretory function, like Mrp2. This work aims to investigate whether these harmful effects are mediated by the oxidative stress caused by the metal. For this purpose, the capability of the antioxidant agent, vitamin E, to counteract these alterations was studied in male Wistar rats. Aluminum hydroxide (or saline in controls) was administered ip (27 mg/kg body weight, three times a week, for 90 d). Vitamin E (600 mg/kg body weight) was coadministered, sc. Al increased lipid peroxidation (+50%) and decreased hepatic glutation levels (-43%) and the activity of glutation peroxidase (-50%) and catalase (-88%). Vitamin E counteracted these effects total or partially. Both plasma and hepatic Al levels reached at the end of the treatment were significantly reduced by vitamin E (-40% and -44%, respectively; p<0.05). Al increased 4 times the hepatic apoptotic index, and this effect was fully counteracted by vitamin E. Bile flow was decreased in Altreated rats (-37%) and restored to normality by vitamin E. The antioxidant normalized the hepatic handling of the Mrp2 substrates, rose bengal, and dinitrophenyl-S-glutathione, which was causally associated with restoration of Mrp2 expression. Our data indicate that oxidative stress has a crucial role in cholestasis, apoptotic/necrotic hepatocellular damage, and the impairment in liver transport function induced by Al and that vitamin E counteracts these harmful effects not only by preventing free-radical formation but also by favoring Al disposal.

Enteral donor pre-treatment with ursodeoxycholic acid protects the liver against ischaemia-reperfusion injury in rats

Liver donor pre-treatment with ursodeoxycholic acid (UDCA) may protect against injury during transplantation. In the present study we evaluated whether enteral administration of UDCA has an effect on bile flow and protects the liver from injury related to transplantation. Wistar rats were used in liver perfusion (LP) and transplantation (LTx) models. Rats were enterally administered UDCA (800 mg/kg) 3 h before cold perfusion. In LP, bile flow and bile acid composition were analysed. In LTx, serum ALT and liver histology were analysed. LP showed biliary UDCA enrichment up to 36+/-13% in pre-treated rats, causing higher bile flow (P = 0.026) compared with control rats. LTx showed lower ALT and TUNEL positive hepatocytes in the UDCA group (P < 0.02 and P < 0.05). In conclusion, augmented bile salt-dependent bile flow is preserved in the liver after cold storage. Enteral donor pre-treatment with UDCA protects the liver against ischaemia-reperfusion injury.

Reversible cholestasis induced by experimental partial obstruction of the bile duct

The aim of this investigation was to reproduce in rats a partial stenosis of the common bile duct to analyze early liver functional and morphometric changes. The hepatic transport kinetics of sulfobromophthalein (organic anion) and rhodamine B (organic cation) was also investigated, and compartmental analysis of both compounds was performed. The humoral parameters of liver function indicated a cholestasis after 2 days of surgery, which reverted to reach normal values on the seventh day. Tumor necrosis factor alpha serum levels showed a tendency to increase on the second day of stenosis (7 out of 14 rats) while white blood cells increased on the second day of stenosis, and turned to normal levels on the seventh day. Histological studies showed increased volume of portal areas and ductular proliferation, which did no revert during the time of the study (up to 7 days post-op). Conversely, a moderate fibrosis and leukocyte infiltrates in portal areas predominated on the second day of stenosis, but normalized on the seventh day. Bile flow was considerably diminished on the second day of partial obstruction as compared to controls. The mean recovery in bile of sulfobromophthalein after 1h of being injected was low on the second day of stenosis, but normalized on the seventh day. Conversely, that of rhodamine B was very low in all animals. Sulfobromophthalein kinetics showed that hepatic uptake and canalicular excretion were impaired during the second but normalized on the seventh day of stenosis. However, rhodamine B kinetics showed that this compound was poorly excreted in all groups although canalicular excretion increased on the second day. The results suggested a model of obstructive cholestasis induced by the experimental stenosis of the bile duct which was not only reversible but also implicates the role of hepatic inflammation.

Ursodeoxycholate further increases bile-duct cell proliferative response induced by partial bile-duct ligation in rats

BACKGROUND

Bile salts (BSs) stimulate cholangiocyte proliferation in vitro and in vivo in normal rats. In this study, we evaluated the effects of BS-enriched diets on cholangiocyte proliferative activity already triggered by partial bile-duct ligation (pBDL), a surgical model that induces mild cholestatic conditions, focusing our attention on ursodeoxycholate (UDC).

METHODS

Animals (n=45) were fed either a standard diet, or a 0.2% deoxycholate- or 0.2% UDC-enriched diet for 4 weeks. Then, in each group, ten animals underwent pBDL and five underwent sham operation. Serum and biliary BS levels, serum cholestasis and cytolysis indexes, as well as liver conventional histology, apoptosis and proliferative activity were evaluated 48 h after the operation.

RESULTS

Animals that underwent pBDL showed sustained proliferative response compared with sham-operated rats. BS-enriched diets did not influence cholangiocyte proliferation in sham-operated rats. However, significantly increased proliferation was observed in pBDL rats fed a UDC-enriched diet. The evaluation of humoral and histological parameters excluded the possibility that the increased proliferation induced by UDC-enriched diet could be related to concomitant liver cell damage.

CONCLUSION

A UDC-enriched diet is able to amplify the magnitude of the cholangiocyte hyperplastic process, which occurs by a stimulatory mechanism after partial bile-duct ligation.

Changes in extrathymic T cells in the liver and intestinal intraepithelium in mice with obstructive jaundice

Recently, T cells were classified into two categories: intrathymic T cells (ITCs; thymus-derived T cells) and extrathymic T cells (ETCs). ETC, localized in the liver and intestinal intraepithelium (IE), play an important immunologic role in the suppressed condition of T-cell development in the thymus. Given the fact that complications of surgery in patients with obstructive jaundice are often related to immunosuppression in the gut-liver circulation, we attempted to investigate the changes in the proportion of ETCs in mice with obstructive jaundice. Three mice models were prepared ( n = 10 per group): sham group with simple laparotomy; ligation group with common bile duct ligation; deoxycholic acid (DCA) group with an oral intake of DCA as a model of the presence of bile salts in the gut lumen. In each model, total mononuclear cells (MNCs), ITCs in the thymus, and ETCs in the liver and IE were counted using monoclonal antibodies in conjunction with a two-color immunofluorescence test by flow cytometry. In the ligation group the number of MNCs was reduced in the thymus and IE, and only those in the IE recovered after oral intake of DCA. A decrease of ITCs in the thymus and the increase in ETCs in the liver and IE occurred simultaneously during the early phase of biliary obstruction. At day 7 after biliary obstruction, ETCs in the livers of the DCA and ligation groups decreased to nearly the level in the sham group. However, on day 7 the ETCs in the IE remained significantly higher in the DCA group than in the ligation group. These results suggested that ETCs can act in place of ITCs at an early phase of obstructive jaundice, and the presence of bile in the gut lumen may be associated with the consumption of ETCs in the IE, a reaction that may bring about improved immunoreactivity.

Ursodeoxycholic acid aggravates bile infarcts in bile duct-ligated and Mdr2 knockout mice via disruption of cholangioles

BACKGROUND & AIMS

The effects of ursodeoxycholic acid (UDCA) in biliary obstruction are unclear. We aimed to determine the effects of UDCA in bile duct-ligated and in Mdr2 knockout (Mdr2(-/-)) mice with biliary strictures.

METHODS

Mice fed UDCA (0.5% wt/wt) or a control diet were subjected to common bile duct ligation (CBDL), selective bile duct ligation (SBDL), or sham operation. UDCA was also fed to 2-month-old Mdr2(-/-) mice. Serum biochemistry, liver histology, and mortality rates were investigated. The biliary tract was studied by plastination, India ink injection, and electron microscopy. The effects of UDCA on biliary pressure were determined by cholangiomanometry.

RESULTS

UDCA feeding in CBDL mice increased biliary pressure, with subsequent rupture of cholangioles and aggravation of hepatocyte necroses, resulting in significantly increased mortality. UDCA feeding in SBDL mice aggravated liver injury exclusively in the ligated lobe. Mdr2(-/-) mice developed liver lesions resembling sclerosing cholangitis characterized by biliary strictures and dilatations. UDCA induced bile infarcts in these animals.

CONCLUSIONS

UDCA aggravates bile infarcts and hepatocyte necroses in mice with biliary obstruction via disruption of cholangioles as a result of increased biliary pressure caused by its choleretic action.

Ursodeoxycholate and tauroursodeoxycholate inhibit cholangiocyte growth and secretion of BDL rats through activation of PKC alpha

Accumulating bile acids (BA) trigger cholangiocyte proliferation in chronic cholestasis. The aim of this study was to determine if ursodeoxycholate (UDCA) or tauroursodeoxycholate (TUDCA) chronic feeding prevents the increased cholangiocyte growth and secretion in bile duct-ligated (BDL) rats, if UDCA and TUDCA effects are associated with increased cholangiocyte apoptosis, and to determine if this inhibition is dependent on increased intracellular Ca(2+) ([Ca(2+)](i)) and activation of protein kinase C (PKC) alpha. Immediately after BDL, rats were fed UDCA or TUDCA (both 275 micromol/d) for 1 week. We determined the number of bile ducts in liver sections, cholangiocyte proliferation (by measurement of H(3) histone and proliferating cellular nuclear antigen in isolated cholangiocytes), and ductal secretion. In purified cholangiocytes from 1-week BDL rats, we evaluated if UDCA and TUDCA directly inhibit cholangiocyte proliferation and secretin-stimulated adenosine 3', 5'-monophosphate levels. We determined if UDCA and TUDCA activate PKC, increase [Ca(2+)](i), and alter the apical BA transporter (ABAT) expression in cholangiocytes. UDCA and TUDCA inhibited in vivo the cholangiocyte proliferation, secretion, and ABAT expression. In vitro UDCA and TUDCA inhibition of cholangiocyte growth and secretion required increased [Ca(2+)](i) and PKC alpha. In conclusion, activation of Ca(2+)-dependent PKC alpha is required for UDCA and TUDCA inhibition of cholangiocyte growth and secretion. Reduced cholangiocyte ABAT may decrease endogenous BA stimulation of cholangiocyte growth and secretion.

Adaptive hepatic changes in mild stenosis of the common bile duct in the rat

Adaptive hepatic changes were investigated in rats with mild stenosis of the common bile duct and in sham-operated controls. The studies were performed 24 h and 7-12 days postoperatively. A continuous intravenous infusion of taurocholic acid at stepwise-increasing rates was performed to explore the responses to bile acid effects. During the infusion, bile flow and the outputs of bile acids, phospholipids, cholesterol, alkaline phosphatase and gamma glutamyl transpeptidase were studied. At the end of the infusion, hepatic morphometric measurements were performed. In other experimental sets, biliary excretions of horseradish peroxidase, a marker of microtubule-dependent vesicular transport in the hepatocyte, and sulphobromophthalein, a well-known organic anion model, were studied. In other rats, bile acid pool size and composition were determined by depletion of bile. The results in rats with mild stenosis maintained for 24 h showed a greater susceptibility to the toxicity of taurocholic acid, as revealed by the abrupt decrement in bile flow at high rates of infusion, and increased outputs of phospholipids and canalicular enzymes. Conversely, rats with mild stenosis maintained for 7-12 days showed decreased bile acid maximum secretory rate and biliary outputs of phospholipids and canalicular enzymes, as well as hepatocyte hypertrophy. These findings may explain the limited hepatic and systemic repercussion of experimental mild stenosis of the common bile duct and help us to understand the early stages of constriction of the common bile duct in man.

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.

Effect of sodium tauroursodeoxycholate (UR-906) on liver dysfunction in bile duct-ligated rats

We investigated the effect of sodium tauroursodeoxycholate (UR-906) on cholestasis in common bile duct-ligated rats in comparison with the effect of dehydrocholic acid. UR-906 (30-180 mumol/kg) and dehydrocholic acid (180 mumol/kg) were intravenously given once daily for consecutive 20 days in rats and the common bile duct was ligated for the last 10 days. On the next day after the last test drug administration, serum biochemical and plasma hemostatic variables were determined. UR-906 significantly ameliorated the elevation of serum cholesterol, phospholipid, bilirubin and bile acid concentrations in bile duct-ligated rats. UR-906 significantly suppressed the prolongation of plasma prothrombin time and activated partial thromboplastin time. Furthermore, UR-906 significantly suppressed the decreases in plasma coagulation factor II and X activities. However, dehydrocholic acid did not cause significant changes in any of the variables examined in this model. These results suggest that UR-906 has a beneficial effect against cholestasis induced by bile duct ligation in rats and that this drug may be useful in the treatment of clinical cholestatic disorders.

Rat model of mild stenosis of the common bile duct

Several techniques for developing incomplete obstruction of the common bile duct have been described but none of them properly represents a compression or constriction of the bile duct. In this study, a mild stenosis of the common bile duct was achieved in the rat by means of a double ligature including a cannula that could be easily slipped out of the ligatures. Sham-operated rats were used as controls. The studies, performed 7-10 days postoperatively, indicated that in ligated rats a duct constriction was produced, made evident by an increase of the biliary pressure, an upstream dilatation of the bile duct, an increase of the liver volume constituted by portal tracts, and ductular proliferation. Serum parameters were practically similar in ligated and control rats, except for a slight increase in serum bilirubin. Following intravenous injection of sodium taurocholate there were rapid increases of bile flow and bile salt output in both groups, but choleresis induced by sodium taurocholate was higher in ligated rats than in controls. The clearances of [14C]erythritol and [14C]sucrose suggested that ductular water contributing to bile flow and changes in biliary permeability were not involved in ligated rats. The limited repercussion of humoral effects and hepatic behaviour seen in ligated rats despite the morphological alterations induced make the mild stenosis of the bile duct a good model for the study of early stages of compression or constriction of the biliary tract.

Bile acids in the assessment of hepatocellular function

Bile acids, which are synthesized in the liver from cholesterol, are important in the production of bile flow, excretion of cholesterol, and intestinal digestion and absorption of fats and fat-soluble vitamins. Increases and/or alterations in concentrations of bile acids in serum are specific and sensitive indicators of hepatobiliary disorders. Synthesis of bile acids in hepatocytes involves steps in endoplasmic reticulum, cytosol, mitochondria, and peroxisomes. Other important hepatocellular processes involving bile acids include active uptake by the basolateral membrane, intracellular transport, P-450-mediated conjugations and hydroxylations, and canalicular secretion. Hydrophobic bile acids produce hepatotoxicity in vivo and in vitro. In experimental and epidemiologic studies, some of these forms have been identified as causative agents in the development of colon and liver (experimental only) cancer. Conversely, several hydrophilic forms, primarily ursodeoxycholic acid, have demonstrated cytoprotective properties in a variety of clinical and experimental hepatobiliary diseases and disorders. Because bile acids can have dramatically different properties and effects, determination of mechanisms of action of these compounds has become an active area of research. Primary isolated hepatocytes provide an opportunity to investigate bile acid-related functions and effects in well-designed, carefully controlled studies. Short-term cultures have been used to study a variety of issues related to bile acids, including cytotoxicity, synthesis, and hepatocellular processing. With these systems, however, many functions of mature hepatocytes, including those pertaining to bile acids, can be lost when cultures are maintained for more than several days. Recent developments in culture techniques permit long-term maintenance of functionally stable, differentiated cells. Pertaining to bile acid research, these systems remain to be fully characterized but, in appropriate situations, they should provide important alternatives to in vivo studies and short-term in vitro assays.

Effect of ursodeoxycholic acid on biochemical parameters, hepatocyte proliferation and liver histology in galactosamine hepatitis in the rat

The effect of oral administration of ursodeoxycholic acid (UDCA) on biochemical parameters, liver histology and liver cell proliferation was investigated in rats with galactosamine hepatitis. Treatment with UDCA led to a decrease of aminotransferases, but did not show any significant changes in liver histology or liver cell proliferation. The improvement of liver enzymes without change of histology in this animal model of hepatitis following treatment with UDCA is in agreement with results obtained from clinical trials with UDCA in patients with chronic viral hepatitis.

Hepatocyte proliferation in primary biliary cirrhosis as assessed by proliferating cell nuclear antigen and Ki-67 antigen labelling

Expression of the proliferating cell nuclear antigen and Ki-67 antigen by hepatocytes was investigated in liver tissue specimens of 29 patients with primary biliary cirrhosis (stage I 13, stage II 6, stage III 5 and stage IV 5 patients) prior to treatment with ursodeoxycholic acid and of five control subjects using immunocytochemical methods. Proliferating cell nuclear antigen and Ki-67 expression were reevaluated in seven patients after 3 years of treatment with ursodeoxycholic acid. Proliferating cell nuclear antigen labelling indices were significantly higher in primary biliary cirrhosis (stage I, 6.4% to 32.4%, median, 10.9%; stage II, 9.6% to 21.6%, median 11.4%; stage III, 5.2% to 12.5%, median, 7.6%; stage IV, 3.8% to 8.9%, median, 5.6%) than in controls (0% to 0.5%, median, 0.1%; p < 0.005). Ki-67 antigen labelling counts were lower than proliferating cell nuclear antigen indices but elevated in all stages of primary biliary cirrhosis (stage I, 0.5% to 3.5%, median 2.0%; stage II, 1.8% to 3.6%, median 2.6%; stage III, 1.3% to 2.5%, median 1.9%; stage IV, 0.4% to 1.7%, median 1.0%) compared with controls (0% to 0.5%, median 0.3%; p < 0.005). After ursodeoxycholic acid treatment, mean proliferating cell nuclear antigen and Ki-67 labelling indices decreased from a median of 9.0% (range, 3.8% to 32.4%) to a median of 7.8% (range, 4.5% to 17.2%; p = 0.045) for proliferating cell nuclear antigen and from a median of 2.5% (range, 0.8% to 3.6%) to a median of 2.1% (range, 0.9% to 3.1%; p = 0.031) for Ki-67 antigen. It is concluded that hepatocyte proliferation is markedly increased in primary biliary cirrhosis, particularly in the early stages of the disease, and that ursodeoxycholic acid treatment reduces proliferative activity in primary biliary cirrhosis.