In PSC with dominant bile duct stenosis, IBD is associated with an increase of carcinomas and reduced survival.

BACKGROUND & AIMS: In patients with primary sclerosing cholangitis (PSC) treated with ursodeoxycholic acid (UDCA), dominant stenoses are associated with reduced survival free of liver transplantation and the role of inflammatory bowel disease (IBD) in such patients is unclear. In the present study the influence of IBD on the outcome in patients with and without dominant stenosis has been evaluated. METHODS: In a prospective study, 171 patients were followed for up to 20 years. All patients were treated with ursodeoxycholic acid; patients with dominant stenosis in addition were treated endoscopically. RESULTS: A total of 97 out of 171 patients had or developed dominant bile duct stenoses and 96 out of 97 were treated endoscopically. In patients with dominant stenosis without IBD, no carcinoma was found whereas all six bile duct and two gallbladder carcinomas and 6/7 colo-rectal carcinomas were found in patients with dominant stenosis with IBD (p=0.012). In patients without dominant stenosis but with IBD, 1 out of 7 had colo-rectal carcinoma. In patients with dominant stenosis without IBD (n=30), actuarial survival free of liver transplantation at 18 years was 77.8% and in those with dominant stenosis and inflammatory bowel disease (n=67) it was 23.0% (p=0.045). In PSC patients without dominant stenosis and without IBD (n=21), actuarial survival free of liver transplantation at 18 years was 68.2% and in those with inflammatory bowel disease (n=53) it was 78.4% (n.s.). CONCLUSIONS: In patients without dominant stenosis, IBD had no effect on the incidence of carcinomas and survival. Only patients with dominant stenosis with additional IBD had an increased carcinoma rate. This may contribute to the reduced survival free of liver transplantation in such patients.

Influence of dominant bile duct stenoses and biliary infections on outcome in primary sclerosing cholangitis.

BACKGROUND/AIMS: In primary sclerosing cholangitis (PSC) dominant stenoses are frequently associated with bacterial, and in part, also fungal infections of the bile ducts. In the present study, the influence of dominant stenoses and of biliary infections on the long-term outcome was studied. METHODS: In a prospective study, 171 patients were followed up for 20 years. All patients were treated with ursodeoxycholic acid. Dominant stenoses were treated endoscopically and during endoscopic procedures, bile was obtained for microbiologic analysis. RESULTS: Of the 171 patients, 97 had or developed major bile duct stenoses and 96/97 were treated endoscopically. In the 55/97 patients with dominant stenosis, bile samples were obtained and of these, 41/55 had bacteria, five had also Candida and 2/55 had only Candida in their bile. Survival free of liver transplantation in patients without dominant stenosis at 18 years was 73.1% and of patients with dominant stenosis was 25.0% (p=0.011). Bacteria in bile had no effect on survival whereas Candida in bile was associated with reduced survival (p=0.025). CONCLUSIONS: In patients with dominant stenosis, survival free of liver transplantation is reduced. Bacteria in bile do not worsen the outcome if dominant stenoses are opened endoscopically and infection is adequately treated with antibiotics. Candida in bile is associated with a poor prognosis and these patients need liver transplantation relatively soon.

Retrieval of the rat canalicular conjugate export pump Mrp2 is associated with a rearrangement of actin filaments and radixin in bile salt-induced cholestasis.

UNLABELLED: Bile salts may initiate or aggravate cholestasis in man. Infusion of Taurochenodeoxycholate (TCDCA) represents a model of bile salt-induced cholestasis in rat. The events leading to cholestasis are incompletely understood. The canalicular conjugate export pump Mrp2 is the major driving force for the bile salt-independent bile flow. Redistribution of Mrp2 has been suggested to cause reduction in bile flow in others models of acute cholestasis (i.e. endotoxin, phalloidin, GSH-depletion). We have studied the effects of TCDCA on the distribution of Mrp2 and P-glycoproteins with respect to changes in the actin cytoskeleton and actin associated proteins radixin and ZO-1. Bile duct cannulated rats were infused with TCDCA (0.1 and 0.4 micromol/min/100g body weight) and bile flow was measured. After 30 min livers were removed and distribution of Mrp2, P-glycoproteins, actin, actin-associated radixin and ZO1 were studied by immunofluorescence analysis. TCDCA at subcholestatic amounts (0.1 micromol/min/100 g body weight) led to distortion and dilation of the canaliculi which was apparent in actin, ZO-1, and Mrp2 fluorescence. Administration of higher amounts of TCDCA (0.4 micromol/min/100g body weight) led to a reduction of bile flow to 31 % of control bile flow. Radixin, which localized strictly to the plasmamembrane in controls, was detected in intracellular structures partially colocalizing with actin aggregates especially at the sinusoidal membranes as visualized by double-immunofluorescence staining. Mrp2 appeared in pericanalicular membrane structures in cholestatic animals whereas P-glycoproteins remained unchanged under these conditions. CONCLUSIONS: Bile salt-induced cholestasis is associated with changes of the actin cytoskeleton and actin binding protein radixin and a retrieval of the canalicular export pump Mrp2.

The incidence of cholangiocarcinoma in primary sclerosing cholangitis after long-time treatment with ursodeoxycholic acid.

BACKGROUND/AIMS: Cholangiocarcinoma represents a serious complication of primary sclerosing cholangitis. Ursodeoxycholic acid may possibly influence the incidence of cholangiocarcinoma in man. The aim of this study was to evaluate the incidence rate of cholangiocarcinoma in a large group of primary sclerosing cholangitis patients after long-time treatment with ursodeoxycholic acid. PATIENTS AND METHODS: From May 1987 up to May 2005 a total of 150 patients with primary sclerosing cholangitis but without evidence of cholangiocarcinoma at entry were included in the study. All patients were treated with ursodeoxycholic acid and controls were performed in at least yearly intervals. RESULTS: The median treatment time of the 150 patients was 6.4 years. Altogether five patients developed a cholangiocarcinoma during treatment yielding a rate of 3.3%. The patients developed 0.58 cholangiocarcinoma per 100 patient-years in years 0-2.5, 0.59 cholangiocarcinoma in years 2.5-8.5, and no cholangiocarcinoma thereafter up to 18 years after entry into the study. The Kaplan-Meier estimate of cholangiocarcinoma incidence during ursodeoxycholic acid treatment reached a plateau after 8.3 years. SUMMARY AND CONCLUSION: The annual incidence rate of cholangiocarcinoma in primary sclerosing cholangitis treated with ursodeoxycholic acid is lower than expected and decreases with time of treatment.

Treatment of primary sclerosing cholangitis.

Aims of treatment for primary sclerosing cholangitis are as follows: prevention of progression of hepatobiliary disease, reduction of symptoms and consequences of cholestasis (pruritus, osteoporosis), and prevention of complications (colorectal cancer, hepatobiliary cancer). Ursodeoxycholic acid (UDCA) improves biliary secretion and laboratory parameters of cholestasis, but its effects on liver histology and survival are not clear. It reduces the incidence of dysplasias and carcinomas of the colon in patients with colitis and possibly has a beneficial effect on the incidence of bile duct carcinomas. At present, UDCA represents the most promising therapeutic option. Immunosuppressive treatment has not been proven to be effective; it appears to be indicated in the overlap syndrome with autoimmune hepatitis but may be harmful in bacterial cholangitis. Bacterial cholangitis is common in patients with dominant stenoses and requires antibiotic treatment. Endoscopic treatment of dominant stenoses improves cholestasis and prolongs survival in comparison to predicted survival. Pruritus represents a problem in some patients, and cholestyramine represents the first-line treatment. If ineffective, opioid antagonists, rifampin, or ondansetron may be tried. For treatment of osteoporosis and osteopenia, calcium and vitamin D supplementation are recommended, and in selected cases, bisphosphonates may be indicated. In patients with severe cholestasis and coagulation defects, parenteral supplementation of vitamin K may be indicated. During treatment, all patients should be regularly screened for colonic and bile duct carcinomas. Patients with cirrhosis of the liver and its complications are treated accordingly, and in end-stage disease, liver transplantation is indicated.

Liver-homing of purified glucose oxidase: a novel in vivo model of physiological hepatic oxidative stress (H2O2).

BACKGROUND/AIMS: Reactive oxygen species (ROS), such as H2O2, are implicated in normal and pathological liver function. However, due to the lack of suitable in vivo models of ROS generation the (patho) physiological relevance of H2O2 remains controversial. METHODS: We established a novel model of sustained hepatic H2O2 release using intravenous administration of purified Aspergillus niger glucose oxidase (GOX) in rats. RESULTS: GOX is rapidly cleared from the blood stream and almost exclusively localizes to Kupffer cells. GOX maintained its ability to generate H2O2 over 24h. While sublethal GOX doses induced hepatocellular necrosis, our morphological and functional studies show that lower levels of GOX which generate H2O2 comparable to release by inflammatory cells are non-toxic and do not induce histological inflammation. However, these non-toxic H2O2 levels increased oxidized glutathione and induced heme oxygenase 1 in the liver. In addition, several hepatocyte transporters were downregulated, while no decrease of bile formation, a sensitive marker of liver function, was observed. CONCLUSIONS: Our in vivo model allows to study the effects of extracellular H2O2 in the liver as is released by inflammatory cells. Thus analysis of the role of this major ROS in the absence of confounding inflammatory cofactors will be possible.

Endoscopic treatment of dominant stenoses in patients with primary sclerosing cholangitis.

Primary sclerosing cholangitis is characterized by progressive fibrosing inflammation of the bile ducts, leading to their obliteration, which results in cholestasis and, finally, cirrhosis of the liver. Over time, the majority of patients with advanced disease develop dominant stenoses of major bile ducts. Ursodeoxycholic acid (UDCA) treatment does not prevent the development of such stenoses. Endoscopic measures allow the opening of short- and long-segment stenoses of the common bile duct and also of short segment stenoses of the hepatic ducts. Inpatients treated by early endoscopic dilatation of dominant stenoses, as well as with UDCA,survival may be significantly improved (compared with the predicted survival).

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.

Guanylin regulates chloride secretion in the human gallbladder via the bile fluid.

BACKGROUND & AIMS: The biliary epithelium of bile ducts and gallbladder modifies the composition of primary hepatic bile by absorption and secretion of an electrolyte-rich fluid. The underlying transport mechanisms, however, are still incompletely understood. We investigated the expression, the cellular localization, and the functional role of guanylin, a bioactive intestinal peptide involved in the cystic fibrosis transmembrane conductance regulator (CFTR)-regulated electrolyte/water secretion, in the human gallbladder. METHODS: Peptide-specific antibodies were raised to localize guanylin and its affiliated signaling proteins, i.e., the guanylin receptor, guanylate cyclase C (GC-C), cGMP-dependent protein kinase type II (cGKII), and CFTR in the human gallbladder and cholangiocarcinoma cells (Mz-Cha-1) by RT-PCR, Western blot, and immunocytochemistry. A sensitive ELISA was used to assess the range of guanylin concentration in human bile fluid. The functional role of guanylin was investigated in subconfluent Mz-Cha-1 cell monolayers by isotope efflux experiments. RESULTS: Guanylin and its affiliated signaling proteins are highly expressed in the human gallbladder. Guanylin is localized to secretory epithelial cells of the gallbladder and is present in the bile, whereas GC-C, cGKII, and CFTR are confined exclusively to the apical membrane of the same epithelial cells. Functional studies in Mz-Cha-1 cells identify guanylin as a specific regulator of biliary Cl(-) secretion that very likely is mediated by an intracellular increase of cGMP-concentration. CONCLUSIONS: Based on the present findings and on the functional role of guanylin in other epithelia, it is likely that gallbladder epithelial cells synthesize and release guanylin into the bile to regulate electrolyte secretion by a paracrine/luminocrine signaling pathway.

Regulation of rat organic anion transporters in bile salt-induced cholestatic hepatitis: effect of ursodeoxycholate.

Hepatic uptake of organic anions, including bile salts, is mediated by members of the organic anion-transporting polypeptide (Oatp) family. In rat liver, Oatp1 (Slc21a1), Oatp2 (Slc21a5), and Oatp4 (Slca10) are expressed at the basolateral membrane of hepatocytes and may be differentially regulated under pathophysiologic conditions such as cholestasis. The aim of this study was to determine the effects of cholic acid (CA) and ursodeoxycholic acid (UDCA) on the expression of Oatp4 compared with Ntcp, Oatp1, and Oatp2. Wistar rats were fed with CA (0.5%) or both CA (0.5%) and UDCA (0.25%) for 3 weeks. Oatp expression was studied by Northern and Western blot analysis as well as immunofluorescence analysis. Transport function was compared measuring biliary secretion of (14)C-CA and (14)C-taurocholic acid (TCA). In CA-fed animals, biliary secretion of (14)C-CA and (14)C-TCA was markedly delayed over 40 minutes compared with controls. Accordingly, Oatp4 protein was significantly down-regulated in CA-fed animals together with Oatp1 and Ntcp. Cofeeding of CA plus UDCA prevented the impairment of (14)C-CA and (14)C-TCA secretion and the down-regulation of Oatp4. Oatp4 messenger RNA (mRNA) levels did not differ significantly between bile salt-fed groups, suggesting a posttranscriptional effect of CA on Oatp4 expression. In contrast to Oatp1 and Oatp4, Oatp2 protein expression was increased by CA feeding, indicating a differential regulation of Oatp transporters. In conclusion, we show that CA feeding may cause cholestasis associated with a posttranscriptional down-regulation of Oatp4. UDCA may prevent impairment of hepatic function by restoring hepatic transporter expression.

Sensitive and real-time determination of H2O2 release from intact peroxisomes.

Peroxisomes are essential and ubiquitous cell organelles having a key role in mammalian lipid and oxygen metabolism. The presence of flavine oxidases makes them an important intracellular source of H(2)O(2): an obligate product of peroxisomal redox reactions and a key reactive oxygen species. Peroxisomes proliferate in response to external signals triggered by peroxisome-proliferator-activated receptor signalling pathways. Peroxisome-derived oxidative stress as a consequence of this proliferation is increasingly recognized to participate in pathologies ranging from carcinogenesis in rodents to alcoholic and non-alcoholic steatosis hepatitis in humans. To date, no sensitive approach exists to record H(2)O(2) turnover of peroxisomes in real time. Here, we introduce a sensitive chemiluminescence method that allows the monitoring of H(2)O(2) generation and degradation in real time in suspensions of intact peroxisomes. Importantly, removal, as well as release of, H(2)O(2) can be assessed at nanomolar, non-toxic concentrations in the same sample. Owing to the kinetic properties of catalase and oxidases, H(2)O(2) forms fast steady-state concentrations in the presence of various peroxisomal substrates. Substrate screening suggests that urate, glycolate and activated fatty acids are the most important sources for H(2)O(2) in rodents. Kinetic studies imply further that peroxisomes contribute significantly to the beta-oxidation of medium-chain fatty acids, in addition to their essential role in the breakdown of long and very long ones. These observations establish a direct quantitative release of H(2)O(2) from intact peroxisomes. The experimental approach offers new possibilities for functionally studying H(2)O(2) metabolism, substrate transport and turnover in peroxisomes of eukaryotic cells.

Expression and localization of the multidrug resistance-associated protein 3 in rat small and large intestine.

Multidrug resistance-associated protein 3 (MRP3; symbol ABCC3), has been shown to mediate ATP-dependent transport of organic anions including 17beta-glucuronosyl estradiol, glucuronosyl bilirubin, monovalent, and sulfated bile salts. MRP3 mRNA expression was reported in rat intestine suggesting a role of MRP3 in the intestinal transport. We examined the expression and localization of MRP3 in rat small and large intestine by RT-PCR, immunofluorescence, and immunoblot analysis. MRP3 was identified in all intestinal segments by RT-PCR. MRP3 expression was low in duodenum and jejunum but markedly increased in ileum and colon. With the use of a rat MRP3 specific antibody, MRP3 was localized to the basolateral domains of enterocytes. Immunofluorescence analysis and immunoblot analysis confirmed a strong expression of rat MRP3 in ileum and colon. In contrast, MRP2 was predominantly expressed in the proximal segments of rat small intestine. Our findings demonstrate a high expression of rat MRP3 in ileum and colon and provide evidence for an involvement of MRP3 in the ATP-dependent transport of organic anions, including bile salts from the enterocyte into blood.