Molecular aspects of membrane stabilization by ursodeoxycholate [see comment]

Pharmacotherapies for Drug-Induced Liver Injury: A Current Literature Review

Drug-induced liver injury (DILI) has become a serious public health problem. For the management of DILI, discontinuation of suspicious drug or medicine is the first step, but the treatments including drugs and supporting approaches are needed. Reference to clinical patterns and disease severity grades of DILI, the treatment drugs were considered to summarize into hepatoprotective drugs (N-acetylcysteine and Glutathione, Glycyrrhizin acid preparation, Polyene phosphatidylcholine, Bicyclol, Silymarin), anticholestatic drug (Ursodeoxycholic acid, S-adenosylmethionine, Cholestyramine), immunosuppressants (Glucocorticoids) and specific treatment agents (L-carnitine, Anticoagulants). The current article reviewed the accumulated literature with evidence-based medicine researches for DILI in clinical practice. Also the drawbacks of the clinical studies involved in the article, unmet needs and prospective development for DILI therapy were discussed.

Clinical features, concurrent disorders, and survival time in cats with suppurative cholangitis-cholangiohepatitis syndrome

OBJECTIVE

To characterize clinical features, comorbidities, frequency of bacterial isolation, and survival time in cats with suppurative cholangitis-cholangiohepatitis syndrome (S-CCHS).

ANIMALS

168 client-owned cats with S-CCHS.

PROCEDURES

Data were prospectively (1980 to 2019) collected regarding clinical features, comorbidities, bacterial infection, illness duration, and treatments. Variables were evaluated for associations with survival time.

RESULTS

Median age of cats was 10.0 years, with no breed or sex predilection observed. Common clinical features included hyporexia (82%), hyperbilirubinemia (80%), lethargy (80%), vomiting (80%), jaundice (67%), weight loss (54%), and hypoalbuminemia (50%). Comorbidities included extrahepatic bile duct obstruction (53%), cholelithiasis (42%), cholecystitis (40%), and ductal plate malformation (44%) as well as biopsy-confirmed inflammatory bowel disease (60/68 [88%]) and pancreatitis (41/44 [93%]). Bacterial cultures were commonly positive (69%) despite prebiopsy antimicrobial administration in most cats. Of surgically confirmed choleliths, diagnostic imaging identified only 58%. Among 55 cats with "idiopathic pancreatitis," 28 (51%) were documented to have transiting choleliths, and 20 had pancreatic biopsies confirming pancreatitis. Cholelithiasis (with or without bile duct obstruction) and cholecystectomy were associated with survival advantages. Survival disadvantages were found for leukocytosis, ≥ 2-fold increased alkaline phosphatase, and hyperbilirubinemia. Cholecystoenterostomy had no survival impact. Cats with ductal plate malformations were significantly younger at diagnosis and death than other cats. Chronic treatments with antimicrobials, S-adenosylmethionine, and ursodeoxycholic acid were common postbiopsy.

CLINICAL RELEVANCE

S-CCHS in cats was associated with bacterial infection and various comorbidities and may be confused with pancreatitis. Surgically correctable morbidities (ie, cholecystitis, cholecystocholelithiasis) and cholecystectomy provided a significant survival advantage.

Ursodeoxycholyl lysophosphatidylethanolamide protects against hepatic ischemia/reperfusion injury via phospholipid metabolism-mediated mitochondrial quality control

Mitochondrial dysfunction is the leading cause of reactive oxygen species (ROS) burst and apoptosis in hepatic ischemia/reperfusion (I/R) injury. Ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE) is a hepatotargeted agent that exerts hepatoprotective roles by regulating lipid metabolism. Our previous studies have shown that UDCA-LPE improves hepatic I/R injury by inhibiting apoptosis and inflammation. However, the role of UDCA-LPE in lipid metabolism and mitochondrial function in hepatic I/R remains unknown. In the present study, we investigated the role of UDCA-LPE in hepatic I/R by focusing on the interface of phospholipid metabolism and mitochondrial homeostasis. Livers from 28-week-old mice, primary hepatocytes and HepG2 cells were subjected to in vivo and in vitro I/R, respectively. Analyses of oxidative stress, imaging, ATP generation, genetics, and lipidomics showed that I/R was associated with mitochondrial dysfunction and a reduction in phospholipids. UDCA-LPE alleviated mitochondria-dependent oxidative stress and apoptosis and prevented the decrease of phospholipid levels. Our study found that cytosolic phospholipase A₂ (cPLA₂ ), a phospholipase that is activated during I/R, hydrolyzed mitochondrial membrane phospholipids and led to mitochondria-mediated oxidative stress and apoptosis. UDCA-LPE inhibited the interaction between cPLA₂ and mitochondria and reduced phospholipid hydrolysis-mediated injury. UDCA-LPE might regulate the crosstalk between the phospholipid metabolism and the mitochondria, restore mitochondrial function and ameliorate I/R injury.

Tauroursodeoxycholic acid (TUDCA) counters osteoarthritis by regulating intracellular cholesterol levels and membrane fluidity of degenerated chondrocytes

Cholesterol and lipid metabolism are associated with osteoarthritis (OA) in human cartilage. High cholesterol levels in OA chondrocytes leads to decreased membrane fluidity and blocks the signaling cascade associated with the expression of chondrogenic genes. It is known that bile acid plays a role in regulating cholesterol homeostasis and the digestion of fats in the human body. Tauroursodeoxycholic acid (TUDCA), as a member of the bile acid family, also aids in the transport of cellular cholesterol. In this study, we hypothesized that TUDCA might be able to promote the restoration of OA cartilage by reducing membrane cholesterol levels in OA chondrocytes and by stimulating the chondrogenic signaling cascade. To assess this hypothesis, we investigated the effects of TUDCA on degenerated chondrocytes isolated from patients with OA. Importantly, treatment with TUDCA at sub-micellar concentrations (2500 μM) significantly increased cell proliferation and Cyclin D1 expression compared with the controls. In addition, the expression of chondrogenic marker genes (SOX9, COL2, and ACAN), proteins (SOX9 and COL2), and glycosaminoglycan (Chondroitin sulfate) was much higher in the TUDCA-treated group compared to the controls. We also found that TUDCA treatment significantly reduced the intracellular cholesterol levels in the chondrocytes and increased membrane fluidity. Furthermore, the stability of TGF receptor 1 and activity of focal adhesion proteins were also increased following TUDCA treatment. Together, these results demonstrated that TUDCA could be used as an alternative treatment for the restoration of OA cartilage.

Characterization of Radioprotective, Radiomitigative and Bystander Signaling Modulating Effects of Endogenous Metabolites - Phenylacetate, Ursodeoxycholate and Tauroursodeoxycholate - on HCT116 Human Colon Carcinoma Cell Line

Exposures to ionizing radiation can cause depletion in stem cell reservoirs and lead to chronic injury processes that exacerbate carcinogenic and inflammatory responses. Therefore, radioprotective measures, against both acute and chronic biological effects of radiation, require frequent intake of nontoxic natural products, which have practical oral administration. The goal of this study was to characterize the radioprotective, radiomitigative and radiation-induced bystander effect-inhibiting properties of endogenous metabolites: phenylacetate, ursodeoxycholate and tauroursodeoxycholate. Compounds were administered pre- and postirradiation as well as in donor and recipient bystander flasks to analyze whether these might adequately protect against radiation injury as well as facilitate recovery from the exposures. The clonogenic HCT116 p53 wild-type cancer cell line in this study shares characteristics of stem cells, such as high reproductive viability, which is an effective marker to demonstrate compound effectiveness. Clonogenic assays were therefore used to characterize radioprotective, radiomitigative and bystander inhibiting properties of treatment compounds whereby cellular responses to radiation were quantified with macroscopic colony counts to measure cell survival in flasks. The results were statistically significant for phenylacetate and tauroursodeoxycholate when administered preirradiation, conferring radioprotection up to 2 Gy, whereas administration postirradiation and in bystander experiments did not confer radioprotection in vitro. These findings suggest that phenylacetate and tauroursodeoxycholate might be effective radioprotectors, although they possess no radiomitigative properties.

UDCA, NorUDCA, and TUDCA in Liver Diseases: A Review of Their Mechanisms of Action and Clinical Applications

Bile acids (BAs) are key molecules in generating bile flow, which is an essential function of the liver. In the last decades, there have been great advances in the understanding of BA physiology, and new insights have emerged regarding the role of BAs in determining cell damage and death in several liver diseases. This new knowledge has helped to better delineate the pathophysiology of cholestasis and the adaptive responses of hepatocytes to cholestatic liver injury as well as of the mechanisms of injury of biliary epithelia. In this context, therapeutic approaches for liver diseases using hydrophilic BA (i.e., ursodeoxycholic acid, tauroursodeoxycholic, and, more recently, norursodeoxycholic acid), have been revamped. In the present review, we summarize current experimental and clinical data regarding these BAs and its role in the treatment of certain liver diseases.

Ursodeoxycholic acid attenuates 5-fluorouracil-induced mucositis in a rat model

Intestinal mucositis is a commonly encountered complication of chemotherapy. However, there are few effective treatments or preventive methods. Ursodeoxycholic acid (UDCA) stabilizes cell membranes, acts as an antioxidant and inhibits apoptosis, thereby exerting cytoprotective effects. The aim of the present study was to examine the ability of UDCA to protecting against chemotherapy-associated mucositis. Sprague-Dawley rats were randomly assigned to five groups: Control, vehicle + 5-fluorouracil (5-FU), 5-FU + UDCA (10 mg/kg/day), 5-FU + UDCA (100 mg/kg/day) and 5-FU + UDCA (500 mg/kg/day). Following randomization, a single dose of 5-FU was injected and varying amounts of UDCA was administered to each group. UDCA was administered orally to rats for 6 days, beginning 1 day prior to 5-FU administration. The rats were sacrificed 1 day following the last UDCA administration and intestinal tissue specimens were prepared for analysis. UDCA administration attenuated body weight loss, decreased inflammatory cytokine levels and curbed intestinal villus damage in the 10 and 100 mg/kg/day groups. When compared with the jejunal villi lengths in the vehicle+5-FU group (212.8±58.0 µm), those in the 5-FU + UDCA (10 mg/kg/day) and 5-FU + UDCA (100 mg/kg/day) groups were significantly greater [331.3±18.0 µm (P=0.001) and 310.0±112.6 µm (P=0.046), respectively]. Tumor necrosis factor-α and interleukin-6 levels were reduced in the 10 and 100 mg/kg/day UDCA groups (P<0.05). UDCA considerably attenuated the elevation in inflammatory cytokines and intestinal villus damage. The results of the study suggest that UDCA may be used as a protective agent against chemotherapy-associated intestinal mucositis.

Canine Idiopathic Chronic Hepatitis

The World Small Animal Veterinary Association's Liver Standardization Group produced standardized criteria for the histologic diagnosis of canine chronic hepatitis (CH). They define CH by the presence of hepatocellular apoptosis or necrosis, a variable mononuclear or mixed inflammatory cell infiltrate, regeneration, and fibrosis. There are variations in histologic appearance between breeds. Hepatic copper accumulation is an important cause of canine CH. However, where copper accumulation has been ruled out, dogs are said to have idiopathic CH. This article reviews theories regarding the etiopathogenesis of canine CH other than copper accumulation, and its clinical features, diagnostic findings, and management.

Zebrafish larva as a reliable model for in vivo assessment of membrane remodeling involvement in the hepatotoxicity of chemical agents

The easy-to-use in vivo model, zebrafish larva, is being increasingly used to screen chemical-induced hepatotoxicity, with a good predictivity for various mechanisms of liver injury. However, nothing is known about its applicability in exploring the mechanism called membrane remodeling, depicted as changes in membrane fluidity or lipid raft properties. The aim of this study was, therefore, to substantiate the zebrafish larva as a suitable in vivo model in this context. Ethanol was chosen as a prototype toxicant because it is largely described, both in hepatocyte cultures and in rodents, as capable of inducing a membrane remodeling leading to hepatocyte death and liver injury. The zebrafish larva model was demonstrated to be fully relevant as membrane remodeling was maintained even after a 1-week exposure without any adaptation as usually reported in rodents and hepatocyte cultures. It was also proven to exhibit a high sensitivity as it discriminated various levels of cytotoxicity depending on the extent of changes in membrane remodeling. In this context, its sensitivity appeared higher than that of WIF-B9 hepatic cells, which is suited for analyzing this kind of hepatotoxicity. Finally, the protection afforded by a membrane stabilizer, ursodeoxycholic acid (UDCA), or by a lipid raft disrupter, pravastatin, definitely validated zebrafish larva as a reliable model to quickly assess membrane remodeling involvement in chemical-induced hepatotoxicity. In conclusion, this model, compatible with a high throughput screening, might be adapted to seek hepatotoxicants via membrane remodeling, and also drugs targeting membrane features to propose new preventive or therapeutic strategies in chemical-induced liver diseases. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of 6-8 weeks of oral ursodeoxycholic acid administration on serum concentrations of fasting and postprandial bile acids and biochemical analytes in healthy dogs

BACKGROUND

Ursodeoxycholic acid (UDCA) is commonly used for the treatment of hepatobiliary disease. UDCA is a bile acid that can be detected in the bile acid assay. Its effect on biochemical analytes is unknown.

OBJECTIVES

The aim of this study was to determine the effect of 6-8 weeks of UDCA administration on fasting and postprandial concentrations of serum bile acids (SBA), cholesterol, triglycerides, bilirubin, and liver enzyme activities in healthy dogs.

METHODS

Twenty healthy dogs received UDCA for 6-8 weeks. CBC, biochemistry profile, urinalysis, fasting and postprandial SBA, and hepatobiliary ultrasound examination were performed prior to starting UDCA (timepoint 0) and after 6-8 weeks of therapy, while animals were still receiving UDCA (timepoint 1). Timepoint 0 and timepoint 1 values were compared with a paired t-test. SBA were remeasured 72 hours after UDCA discontinuation.

RESULTS

Only mean fasting SBA at timepoint 1 increased significantly (P = .03) from timepoint 0 (2.26 μmol/L at time 0 and 3.81 μmol/L at time 1) but were not elevated above the normal reference interval (0-9 μmol/L). Two dogs had timepoint 1 fasting SBA above the reference interval (10 and 11.7 μmol/L). One dog had timepoint 1 postprandial SBA above the reference interval at 20.1 μmol/L (reference interval 0-17 μmol/L). Repeat SBA 72 hours after UDCA discontinuation were normal.

CONCLUSIONS

Long-term administration of UDCA to healthy dogs may increase fasting SBA above pretreatment values (typically within the reference interval). Long-term administration of UDCA to healthy dogs does not alter liver enzyme activities, and bilirubin, cholesterol, or triglyceride concentrations.

In Barrett's esophagus patients and Barrett's cell lines, ursodeoxycholic acid increases antioxidant expression and prevents DNA damage by bile acids

Hydrophobic bile acids like deoxycholic acid (DCA), which cause oxidative DNA damage and activate NF-κB in Barrett's metaplasia, might contribute to carcinogenesis in Barrett's esophagus. We have explored mechanisms whereby ursodeoxycholic acid (UDCA, a hydrophilic bile acid) protects against DCA-induced injury in vivo in patients and in vitro using nonneoplastic, telomerase-immortalized Barrett's cell lines. We took biopsies of Barrett's esophagus from 21 patients before and after esophageal perfusion with DCA (250 μM) at baseline and after 8 wk of oral UDCA treatment. DNA damage was assessed by phospho-H2AX expression, neutral CometAssay, and phospho-H2AX nuclear foci formation. Quantitative PCR was performed for antioxidants including catalase and GPX1. Nrf2, catalase, and GPX1 were knocked down with siRNAs. Reporter assays were performed using a plasmid construct containing antioxidant responsive element. In patients, baseline esophageal perfusion with DCA significantly increased phospho-H2AX and phospho-p65 in Barrett's metaplasia. Oral UDCA increased GPX1 and catalase levels in Barrett's metaplasia and prevented DCA perfusion from inducing DNA damage and NF-κB activation. In cells, DCA-induced DNA damage and NF-κB activation was prevented by 24-h pretreatment with UDCA, but not by mixing UDCA with DCA. UDCA activated Nrf2 signaling to increase GPX1 and catalase expression, and protective effects of UDCA pretreatment were blocked by siRNA knockdown of these antioxidants. UDCA increases expression of antioxidants that prevent toxic bile acids from causing DNA damage and NF-κB activation in Barrett's metaplasia. Elucidation of this molecular pathway for UDCA protection provides rationale for clinical trials on UDCA for chemoprevention in Barrett's esophagus.

Improved survival with ursodeoxycholic acid prophylaxis in allogeneic stem cell transplantation: long-term follow-up of a randomized study

We report the long-term results of a prospective randomized study on the use of ursodeoxycholic acid (UDCA) for prevention of hepatic complications after allogeneic stem cell transplantation. Two hundred forty-two patients, 232 with malignant disease, were randomized to receive (n = 123) or not to receive (n = 119) UDCA from the beginning of the conditioning until 90 days post-transplantation. The results were reported after 1-year follow-up. UDCA administration reduced significantly the proportion of patients developing high serum bilirubin levels as well as the incidence of severe acute graft-versus-host disease (GVHD), liver GVHD, and intestinal GVHD. In the UDCA prophylaxis group, nonrelapse mortality (NRM) was lower and overall survival better than in the control group. After a 10-year follow-up, the difference in the survival and NRM in favor of the UDCA-treated group, seen at 1 year, was maintained (survival 48% versus 38%, P = .037; NRM 28% versus 41%, P = .01). A landmark analysis in patients surviving at 1 year post-transplantation showed no significant differences between the study groups in the long-term follow-up in chronic GVHD, relapse rate, NRM, disease-free survival, or overall survival. These long-term results continue to support the useful role of UDCA in the prevention of transplant-related complications in allogeneic transplantation.

Ursodeoxycholic acid and bile-acid mimetics as therapeutic agents for cholestatic liver diseases: an overview of their mechanisms of action

Chronic cholestasis and liver inflammation are the two main pathophysiological components of the two major classes of disease - primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) - leading to bile duct destruction and ultimately to cirrhosis and liver failure. Ursodeoxycholic acid (UDCA), initially introduced as a therapeutic approach to counteract the cholestatic components to PBC and PSC, was subsequently shown to exhibit unexpected anti-inflammatory and immunomodulatoty properties. The use of farnesoid X receptor (FXR) and TGR5 agonists in various animal models have confirmed early observations indicating that bile acids are not only toxicants and inflammagens, but also repressors of innate and adaptive immunity. Obeticholic acid is a bile-acid mimetic, with no toxic or inflammagen behavior, that strongly activates FXR to combat the toxic effects of high concentrations of bile acid. Because UDCA is not an FXR agonist, its combination with obeticholic acid could be a promising tool for the treatment of PBC and PSC. In this overview, the biological properties of UDCA, NorUDCA and FXR agonists are highlighted, as well as their overlapping mechanisms of action in inflammatory biliary disorders.

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.

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.

Lipid raft-dependent death receptor 5 (DR5) expression and activation are critical for ursodeoxycholic acid-induced apoptosis in gastric cancer cells

Ursodeoxycholic acid (UDCA) is known as a suppressor of cholestatic liver diseases and colorectal cancer development. Here, we demonstrate that UDCA induces apoptosis without necrotic features in SNU601, SNU638, SNU1 and SNU216 human gastric cancer cells, implying its possible use as an effective chemotherapeutic agent in treatment of gastric cancer. UDCA-induced apoptosis was dominantly mediated by an extrinsic pathway dependent on caspase-8, -6 and -3. UDCA increased expression of death receptor 5 [(DR5), also known as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor 2], and this DR appeared to be responsible for UDCA-induced apoptosis, as evidenced by DR5 knockdown. UDCA triggered formation of lipid rafts that played crucial roles in UDCA-induced apoptotic actions. Lipid rafts were required not only for provision of a proper site for DR5 action but also for mediation of DR5 expression. In addition, reactive oxygen species (ROS) and protein kinase C (PKC) δ appeared to be implicated in UDCA-induced raft-dependent DR5 expression. Our results indicate that UDCA-induced apoptosis is mediated by DR5 expression, which is regulated by the raft formation/ROS production/PKCδ activation pathway and DR5 localization into lipid rafts in gastric cancer cells. Tumor-suppressive activity of UDCA was confirmed in an in vivo system: UDCA (120 mg/kg/day) significantly decreased tumor growth in gastric cancer xenograft mice. Taken together, our results demonstrate that UDCA can be used as a potent chemotherapeutic agent for treatment of gastric cancer.

The correlation between NF-κB inhibition and disease activity by coadministration of silibinin and ursodeoxycholic acid in experimental colitis

NF-κB is one of the most important nuclear factors responsible for overexpression of proinflammatory cytokines. This is demonstrated by increased NF-κB activity and other dependent immune factors in inflammatory bowel disease (IBD). Anti-inflammatory effects of silibinin and ursodeoxycholic acid (UDCA) along with their NF-κB inhibitory property are thought to be beneficial in colitis. Trinitrobenzene sulfonic acid was used to induce colitis rat models. After instillation, 48 rats were treated with oral silibinin, UDCA alone or a combination of both. Intraperitoneal dexamethasone was used in the control group. After 12 days of treatment, colonic samples were tested for the severity of mucosal damage macroscopically and microscopically. The levels of activated NF-κB, IL-1β, TNF-α, myeloperoxidase, thiobarbituric acid reactive substances (TBARS), protein carbonyl, and the antioxidant power of the bowel homogenates were determined. The results indicated a significant reduction in NF-κB activity as well as the levels of IL-1β, TNF-α, TBARS, protein carbonyl, myeloperoxidase activity, and an improvement in antioxidant power of colitis in treated rats. Combination therapy resulted in a more prominent improvement in bowel antioxidant power and myeloperoxidase activity. In conclusion, combination of silibinin and UDCA by inhibition of NF-κB and other relevant inflammatory factors of colitis is a good candidate for management of Crohn's disease.

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.

Ursodeoxycholic acid treatment in patients with cystic fibrosis at risk for liver disease

BACKGROUND

Meconium ileus has been detected as a risk factor for development of liver disease in cystic fibrosis, with influence on morbidity and mortality.

AIMS

To evaluate the effect of early treatment with ursodeoxycholic acid in patients with cystic fibrosis and meconium ileus to prevent chronic hepatic involvement and to explore the potential role of therapy on clinical outcomes.

METHODS

26 cystic fibrosis patients with meconium ileus (16 M, mean age 8,4 years, range 3,5-9) were assigned to two groups: group 1 (14 patients) treated early with ursodeoxycholic acid (UDCAe); group 2 (12 patients) treated with ursodeoxycholic acid at the onset of cystic fibrosis liver disease (UDCAd). Anthropometric data, pulmonary function tests, pancreatic status, complications such as diabetes, hepatic involvement and Pseudomonas aeruginosa colonisation were compared among groups.

RESULTS

A higher prevalence of cystic fibrosis chronic liver disease was observed in the UDCAd group with a statistically significant difference at 9 years of age (p<0.05). Chronic infection by P. aeruginosa was found in 7% of UDCAe and 33% of UDCAd (p<0.05). No differences were observed in nutritional status and other complications.

CONCLUSIONS

Early treatment with ursodeoxycholic acid may be beneficial in patients at risk of developing cystic fibrosis chronic liver disease such as those with meconium ileus. Multicentre studies should be encouraged to confirm these data.

Ursodeoxycholic acid switches oxaliplatin-induced necrosis to apoptosis by inhibiting reactive oxygen species production and activating p53-caspase 8 pathway in HepG2 hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is resistant to chemotherapy. Recently, however, several oxaliplatin-based combinatorial treatments have shown a promising anti-tumor activity in patients with HCC. Presently, we demonstrate that oxaliplatin triggers necrosis more than apoptosis in HepG2, SK-Hep1, SNU-423 and Hep3B HCC cells, while mainly inducing apoptosis in HCT116 and HT29 colon cancer cells. Interestingly, ursodeoxycholic acid (UDCA), a less hydrophobic bile acid that can suppress carcinogenesis, shifted oxaliplatin-induced necrosis to apoptosis in HepG2 cells. The same effect was produced by hydrophilic bile acids (tauroursodeoxycholic acid and taurohyodeoxycholic acid), but not by highly hydrophobic bile acids (deoxycholic acid and chenodeoxycholic acid). UDCA also triggered the necrosis-to-apoptosis switch when cotreated with other platinum-based chemotherapeutic drugs including cisplatin and carboplatin, suggesting that the cell death mode switching effect of UDCA is a general phenomenon when combined with platinum drugs. Oxaliplatin produced high level of reactive oxygen species (ROS) in HepG2 cells and UDCA significantly reduced oxaliplatin-induced ROS generation. In addition, N-acetyl-L-cysteine and the superoxide scavengers butylated hydroxyanisole and dihydroxybenzene-3,5-disulfonic acid attenuated necrosis, indicating a critical role(s) of ROS in occurrence of necrotic death. Apoptosis induced by combined treatment appeared to be mediated by p53-caspase 8-caspase 3 pathway. In conclusion, UDCA switches oxaliplatin-induced necrosis to apoptosis via inhibition of ROS production and activation of the p53-caspase 8 pathway in HepG2 cells. As necrosis and subsequent inflammation are implicated in tumor progression and malignancy, our results imply a potential improved efficacy of UDCA-combined chemotherapy in HCC by reducing inflammatory responses that may be triggered by oxaliplatin.

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.

Bile salt-phospholipid conjugate ursodeoxycholyl lysophosphatidylethanolamide as a hepatoprotective agent

A decrease of hepatocellular phosphatidylcholine (PC) is associated with hepatic injury, e.g., in nonalcoholic steatohepatitis (NASH). Therefore, we evaluated the hepatoprotective effect of a PC-precursor lipid specifically targeted to the liver. We synthesized the bile acid-phospholipid conjugate ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE), which was designed to target PC to hepatocytes by way of bile-acid transport systems. We synthesized a fluorescently labeled analogue UDCA-6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]hexanoyl PE (UDCA-NBDPE) for uptake and metabolism studies. Unexpectedly, the majority of UDCA-NBDPE was still intact and not hydrolyzed efficiently in HepG2 cells. For targeting in vivo, NBD fluorescence from UDCA-NBDPE-injected mice was recovered in the liver the most, whereas injection of NBDPE alone resulted in an even distribution in liver, kidneys, and intestine. Cytoprotection by UDCA-LPE was tested in starvation and tumor necrosis factor alpha (TNF-alpha) apoptosis models using HepG2 cells. Only the intact UDCA-LPE was able to persistently stimulate growth after 36 to 120-hour starvation, and significantly inhibited TNF-alpha-induced apoptosis. In both models, LPC, LPE, UDCA, or UDCA added with LPE exhibited weak to no cytoprotection. UDCA-LPE stabilized mitochondrial membranes by lowering mitochondrial membrane potential. Western blot analyses of phosphorylated Akt and glycogen synthase kinase-3 (GSK-3)alpha/beta revealed that UDCA-LPE activated phosphatidyl inositol 3-kinase (PI3K)/Akt signaling pathways. The PI3K inhibitor LY294002 or Akt small interfering (si)RNA consistently inhibited the proproliferative effects of UDCA-LPE during starvation. The TNF-alpha death-receptor extrinsic pathway involves caspase 8 activation, which is inhibited by cellular FLICE-inhibitory protein (cFLIP); thus, cFLIP siRNA was employed in our studies. cFLIP siRNA was able to reverse the cytoprotective effects of UDCA-LPE during TNF-alpha-induced apoptosis, and UDCA-LPE concomitantly upregulated protein expression of cFLIP(L).

CONCLUSION

UDCA-LPE, which targeted the liver in vivo, elicited potent biological activities in vitro by stimulating hepatocyte growth and by inhibiting TNF-alpha-induced apoptosis. Thus, UDCA-LPE may be suitable for evaluation of treatment efficacy in NASH.

Tauroursodeoxycholic acid prevents E22Q Alzheimer's Abeta toxicity in human cerebral endothelial cells

The vasculotropic E22Q mutant of the amyloid-beta (Abeta) peptide is associated with hereditary cerebral hemorrhage with amyloidosis Dutch type. The cellular mechanism(s) of toxicity and nature of the AbetaE22Q toxic assemblies are not completely understood. Comparative assessment of structural parameters and cell death mechanisms elicited in primary human cerebral endothelial cells by AbetaE22Q and wild-type Abeta revealed that only AbetaE22Q triggered the Bax mitochondrial pathway of apoptosis. AbetaE22Q neither matched the fast oligomerization kinetics of Abeta42 nor reached its predominant beta-sheet structure, achieving a modest degree of oligomerization with a secondary structure that remained a mixture of beta and random conformations. The endogenous molecule tauroursodeoxycholic acid (TUDCA) was a strong modulator of AbetaE22Q-triggered apoptosis but did not significantly change the secondary structures and fibrillogenic propensities of Abeta peptides. These data dissociate the pro-apoptotic properties of Abeta peptides from their distinct mechanisms of aggregation/fibrillization in vitro, providing new perspectives for modulation of amyloid toxicity.

Effect of ursodeoxycholic acid on serum liver enzymes and bile acid metabolism in chronic active hepatitis C virus infection

AIM

Many reports have revealed ursodeoxycholic acid (UDCA) to be effective against chronic hepatitis C virus (HCV). However, some cases resist this therapy and the mechanism of action remains unclear. In this study, UDCA was administered to patients with chronic HCV and the correlation between the bile acids of the biliary bile and serum and the drug efficacy was investigated.

METHODS

Fifteen patients were given 600 mg/day of UDCA for more than 24 weeks. The serum bile acid concentrations and biliary and serum bile acid were collected before and after 24 weeks of UDCA treatment, and composition determined by high-performance liquid chromatography.

RESULTS

The treatment was effective in nine cases (ALT decreased to less than twice the normal values 80 IU/L) and ineffective in six cases. There was no significant difference in the serum bile acid concentrations before and after UDCA treatment between the values of both cases. After UDCA treatment, the serum percentage of UDCA (effective, 62.5 +/- 2.0; ineffective, 53.5 +/- 2.5, (P = 0.02)) and the percentage of chenodeoxycholic acid (CDCA) showed no remarkable changes. In the biliary bile the percentage of CDCA (effective, 30.9 +/- 2.0; ineffective, 20.0 +/- 3.0, (P = 0.007)) and the percentage of UDCA showed no remarkable changes.

CONCLUSION

In the effective cases, the percentage of UDCA in the serum and the percentage of CDCA in biliary bile were significantly higher than in the ineffective cases. This indicates that, when effective, CDCA decreases in hepatocytes and this reduction contributes to hepatoprotection.

The role of membrane cholesterol in determining bile acid cytotoxicity and cytoprotection of ursodeoxycholic acid

In cholestatic liver diseases, the ability of hydrophobic bile acids to damage membranes of hepatocytes/ductal cells contributes to their cytotoxicity. However, ursodeoxycholic acid (UDC), a hydrophilic bile acid, is used to treat cholestasis because it protects membranes. It has been well established that bile acids associate with and solubilize free cholesterol (CHOL) contained within the lumen of the gallbladder because of their structural similarities. However, there is a lack of understanding of how membrane CHOL, which is a well-established membrane stabilizing agent, is involved in cytotoxicity of hydrophobic bile acids and the cytoprotective effect of UDC. We utilized phospholipid liposomes to examine the ability of membrane CHOL to influence toxicity of individual bile acids, such as UDC and the highly toxic sodium deoxycholate (SDC), as well as the cytoprotective mechanism of UDC against SDC-induced cytotoxicity by measuring membrane permeation and intramembrane dipole potential. The kinetics of bile acid solubilization of phosphatidylcholine liposomes containing various levels of CHOL was also characterized. It was found that the presence of CHOL in membranes significantly reduced the ability of bile acids to damage synthetic membranes. UDC effectively prevented damaging effects of SDC on synthetic membranes only in the presence of membrane CHOL, while UDC enhances the damaging effects of SDC in the absence of CHOL. This further demonstrates that the cytoprotective effects of UDC depend upon the level of CHOL in the lipid membrane. Thus, changes in cell membrane composition, such as CHOL content, potentially influence the efficacy of UDC as the primary drug used to treat cholestasis.

TUDCA prevents cholestasis and canalicular damage induced by ischemia-reperfusion injury in the rat, modulating PKCalpha-ezrin pathway

Cholestasis, induced by liver ischemia-reperfusion injury (IRI), is characterized by dilatation of bile canaliculi and loss of microvilli. Tauroursodeoxycholic acid (TUDCA) is an anti-cholestatic agent, modulating protein kinase C (PKC) alpha pathway. PKC reduces ischemic damage in several organs, its isoform alpha modulates ezrin, a key protein in the maintenance of cell lamellipoidal extensions. We evaluated the effects of TUDCA on cholestasis, canalicular changes and PKCalpha-ezrin expression in a rat model of liver IRI. Livers flushed and stored with Belzer solution or Belzer + 10 mm TUDCA (4 degrees C for 6 h) were reperfused (37 degrees C with O(2)) with Krebs-Ringer bicarbonate + 2.5 micromol/min of Taurocholate or TUDCA. Bile was harvested for bile flow assessment. Liver tissue was employed for Electron Microscopy (EM) and for PKCalpha and ezrin immunoblot and immunofluorescence. The same experiments were conducted with the PKCalpha inhibitor Go-6976. TUDCA-treated livers showed increased bile flow (0.25+/-0.17 vs. 0.042+/-0.02 microl/min/g liver, P<0.05) and better preservation of microvilli and bile canalicular area at EM. These effects were associated with increased PKCalpha and ezrin expression (P=0.03 and P=0.04 vs. control respectively), as also confirmed by immunofluorescence data. PKCalpha inhibition abolished these TUDCA effects. TUDCA administration during IRI reduces cholestasis and canalicular damage in the liver modulating PKCalpha-ezrin pathway.

The effect of oral administration of ursodeoxycholic acid and high-dose proton pump inhibitors on the histology of Barrett's esophagus

Bile acids may play a role in the pathogenesis of Barrett's esophagus (BE). Bile composition can be influenced by oral administration of ursodeoxycholic acid (UDCA). We prospectively investigated the effect of proton pump inhibitors (PPI) supplemented with UDCA in vivo in patients with BE. Patients with no or low-grade dysplasia who were clinically asymptomatic on PPI were eligible for the study. In order to exclude the effects of acid reflux, all patients were initially treated with 40 mg esomeprazole (ESO) twice daily for 6 months and continued on this dose till the end of the study (t = 12 months). During a period of 6 months (t = 6 month - t = 12 month) patients were treated with oral UDCA (600 mg twice daily). Patients underwent endoscopy at t = 0 months, t = 6 months and t = 12 months with multiple biopsies of the distal and proximal BE segment, normal squamous and gastric cardia. In addition, pH was measured at t = 0 months and t = 6 months using a BRAVO wireless pH capsule. Bile was sampled at the beginning of the UDCA treatment and 6 months later (t = 6 month and t = 12 month). All biopsies were reviewed for the extent of metaplasia, dysplasia, and acute and chronic inflammation. In addition, proliferation (Ki67), differentiation (villin, cytokeratins 7 and 20) and inflammation (COX-2) were investigated by immunohistochemistry (IHC). Nine patients (mean age 60 years, median BE length 7 cm) were included, of whom six had no dysplasia and three had low-grade dysplasia. pH measurements revealed a normal acid exposure in most patients at t = 0 and t = 6 months. In addition, bile composition analysis demonstrated the efficacy of UDCA. Combining the results of both phases of the study, no significant changes were seen in any of the histological or IHC parameters. Differentiation and proliferation parameters showed no significant changes. In this study, in BE patients who were clinically asymptomatic on PPI, increasing the PPI dose to the maximum for 6 months followed by the addition of UDCA for 6 months did not result in significant histological or IHC changes in their BE.

Bile acids modulate tight junction structure and barrier function of Caco-2 monolayers via EGFR activation

Intestinal and systemic illnesses have been linked to increased gut permeability. Bile acids, whose luminal profile can be altered in human disease, modulate intestinal paracellular permeability. We investigated the mechanism by which selected bile acids increase gut permeability using a validated in vitro model. Human intestinal Caco-2 cells were grown in monolayers and challenged with a panel of bile acids. Transepithelial electrical resistance and luminal-to-basolateral fluxes of 10-kDa Cascade blue-conjugated dextran were used to monitor paracellular permeability. Immunoprecipitation and immunoblot analyses were employed to investigate the intracellular pathway. Redistribution of tight junction proteins was studied by confocal laser microscopy. Micromolar concentrations of cholic acid, deoxycholic acid (DCA), and chenodeoxycholic acid (CDCA) but not ursodeoxycholic acid decreased transepithelial electrical resistance and increased dextran flux in a reversible fashion. Coincubation of 50 muM CDCA or DCA with EGF, anti-EGF monoclonal antibody, or specific src inhibitor 4-Amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP-2) abolished the effect. A concentration of 50 muM of either CDCA or DCA also induced EGF receptor phosphorylation, occludin dephosphorylation, and occludin redistribution at the tight junction level in the same time frame and in a reversible fashion. We conclude that selected bile acids modulate intestinal permeability via EGF receptor autophosphorylation, occludin dephosphorylation, and rearrangement at the tight junction level. The effect is mediated by the src family kinases and is abolished by EGF treatment. These data also support the role of bile acids in the genesis of necrotizing enterocolitis and the protective effect of EGF treatment.

Mechanism of apoptotic effects induced selectively by ursodeoxycholic acid on human hepatoma cell lines

AIM: To investigate the effects of ursodeoxycholic acid (UDCA) on apoptosis and proliferation of hepatoma cell lines.

METHODS: Human hepatoma cell lines HepG2 and BEL 7402 were cultured in medium supplemented with different concentrations of UDCA, normal human hepatic line L-02 was used as control. Cell proliferation, apoptosis and gene expression were detected using methyl thiazolyl tetrazolium (MTT) assay, flow cytometry, Western blot, DNA ladder assay, electron microscopy, and immunocytochemistry.

RESULTS: Ursodeoxycholic acid inhibited the proli-feration of HepG2 and BEL7402 cell lines in a dose-dependent manner. Ursodeoxycholic acid can change cell cycle distribution of HepG2 and BEL7402, the proportion of cells in G₀-G₁ phase increased whereas the proportion of S phase cells and G₂-M phase cells decreased. Ursodeoxycholic acid arrested the cell cycle in G₀-G₁ phase by down-regulating the cell cycle related proteins cyclin D₁, D₃ and retinoblastoma protein (p^Rb). The apoptotic rates of HepG2 and BEL7402 treated with UDCA (1.0 mmol/L) were significantly higher than those of control. In the HepG2 and BEL7402 treated with UDCA, expression of bcl-2 decreased whereas expression of Bax increased, the nuclear fragmentation and chromosomal condensed, cells shrank and lost attachment, apoptotic bodies and DNA ladders appeared. UDCA had no effect in inducing apoptosis on L-02 cell lines.

CONCLUSION: UDCA can selectively inhibit proliferation and induce apoptosis of HepG2 and BEL7402 cell lines by blocking cell cycle and regulating the expression of Bax/bcl-2 genes.

Protective effect of ursodeoxycholic acid on liver mitochondrial function in rats with alloxan-induced diabetes: link with oxidative stress

We investigated the effects of ursodeoxycholic acid (UDCA) on mitochondrial functions and oxidative stress and evaluated their relationships in the livers of rats with alloxan-induced diabetes. Diabetes was induced in male Wistar rats by a single alloxan injection (150 mg kg(-1) b.w., i.p.). UDCA (40 mg kg(-1) b.w., i.g., 30 days) was administered from the 5th day after the alloxan treatment. Mitochondrial functions were evaluated by oxygen consumption with Clark oxygen electrode using succinate, pyruvate+malate or palmitoyl carnitine as substrates and by determination of succinate dehydrogenase and NADH dehydrogenase activities. Liver mitochondria were used to measure chemiluminiscence enhanced by luminol and lucigenin, reduced liver glutathione and the end-products of lipid peroxidation. The activities of both NADH dehydrogenase and succinate dehydrogenase as well as the respiratory control (RC) value with all the substrates and the ADP/O ratio with pyruvate+malate and succinate as substrates were significantly decreased in diabetic rats. UDCA developed the beneficial effect on the mitochondrial respiration and oxidative phosphorylation parameters in alloxan-treated rats, whereas the activities of mitochondrial enzymes were increased insignificantly after the administration of UDCA. The contents of polar carbonyls and MDA as well as the chemiluminescence with luminol were elevated in liver mitochondria of diabetic rats. The treatment with UDCA normalized all the above parameters measured except the MDA content. UDCA administration prevents mitochondrial dysfunction in rats treated with alloxan and this process is closely connected with inhibition of oxidative stress by this compound.

Ursodeoxycholic acid treatment of vanishing bile duct syndromes

Vanishing bile duct syndromes (VBDS) are characterized by progressive loss of small intrahepatic ducts caused by a variety of different diseases leading to chronic cholestasis, cirrhosis, and premature death from liver failure. The majority of adult patients with VBDS suffer from primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Ursodeoxycholic acid (UDCA), a hydrophilic dihydroxy bile acid, is the only drug currently approved for the treatment of patients with PBC, and anticholestatic effects have been reported for several other cholestatic syndromes. Several potential mechanisms of action of UDCA have been proposed including stimulation of hepatobiliary secretion, inhibition of apoptosis and protection of cholangiocytes against toxic effects of hydrophobic bile acids.

Enhancement of DNA topoisomerase I inhibitor–induced apoptosis by ursodeoxycholic acid

Certain hydrophobic bile acids, including deoxycholic acid and chenodeoxycholic acid, exert toxic effects not only in the liver but also in the intestine. Moreover, ursodeoxycholic acid (UDCA), which has protective actions against apoptosis in the liver, may have both protective and toxic effects in the intestine. The goal of the present study was to clarify the mechanisms responsible for the toxic effect of UDCA in intestinal HT-29 cells. Here, we show that UDCA potentiated both phosphatidylserine externalization and internucleosomal DNA fragmentation induced by SN-38, the most potent metabolite of the DNA topoisomerase I inhibitor, CPT-11. Furthermore, the loss of mitochondrial membrane potential as well as mitochondrial membrane permeability transition induced by SN-38 was enhanced in the presence of UDCA, resulting in an increased lethality determined by colony-forming assay. This UDCA-induced increased apoptosis was not due to alteration of either intracellular accumulation of SN-38 or cell cycle arrest by SN-38. The increased apoptosis was best observed when UDCA was present after SN-38 stimulation and was independent of caspase-8 but dependent on caspase-9 and caspase-3 activation. Furthermore, UDCA enhanced SN-38-induced c-Jun NH(2)-terminal kinase activation. In conclusion, UDCA increases the apoptotic effects while decreasing the necrotic effects of SN-38 when added after the topoisomerase I inhibitor, showing potential clinical relevance as far as targeted cell death and improved wound healing are concerned. However, the use of this bile acid as an enhancer in antitumor chemotherapy should be further evaluated clinically.

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

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

Recurrent primary biliary cirrhosis: peritransplant factors and ursodeoxycholic acid treatment post-liver transplant

Primary biliary cirrhosis (PBC) recurs after orthotopic liver transplantation (OLT) in up to one-third of patients. These patients are typically asymptomatic, can be identified by abnormal liver biochemistries, and have evidence of histologic recurrence on liver biopsy. The effect of treatment on recurrence has not been determined. This pilot study evaluates the factors associated with recurrent PBC and describes our experience using ursodeoxycholic acid treatment in this patient population. Forty-eight patients with PBC were followed for at least 1 yr post-OLT, and 27 patients (56%) developed abnormal serum alkaline phosphatase. Seventeen patients (35%) had evidence of recurrent PBC by liver biopsy. Patients with recurrent PBC had a trend toward longer warm ischemia times and more episodes of acute cellular rejection in the first year posttransplant, but this was not significant in multivariate analysis. Donor or recipient age, donor and recipient cytomegalovirus status, and dose of immunosuppression did not correlate with recurrence of PBC. Those patients diagnosed with recurrent PBC were placed on ursodeoxycholic acid, 15 mg/kg daily, with improvement in serum alkaline phosphatase in the majority. In conclusion, recurrent PBC is not infrequent post-OLT, and ursodeoxycholic acid can be used with some benefit post-OLT. Treatment effects on long-term survival are not known.

Options for treatment of primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic progressive cholestatic disease where there is progressive, granulomatous destruction of the middle-sized bile ducts. The disease affects mainly middle-aged women. The association with other autoimmune diseases and the widespread disturbance of the humoral and cellular immune systems has led to the inclusion of PBC as an autoimmune disease. However, there are several lines of evidence that suggest that both host and environmental factors are implicated in triggering the disease. Without a clear aetiology, it is difficult to find a logical approach to treatment. Well constructed clinical trials are difficult to run because of the variable and long natural history of the disease; and suitable endpoints are difficult to define and validated surrogate endpoints have not been defined. The only drug licensed for use is the bile acid, ursodeoxycholic acid. This drug is associated with significant biochemical improvement and improvement in the immunological disturbances (including a reduction in the titre of the diagnostic autoantibody, antimitochondrial antibody), but the effect on survival and histological progression is still controversial. There is little effect on symptoms. Nonetheless, its safety and lack of toxicity have meant that it has become the drug of choice and most studies now assess the effect of additional treatments. Many other agents have been studied. There is some evidence, from prospective, controlled studies, for a beneficial effect of azathioprine and ciclosporin (cyclosporine); evidence for a beneficial effect of corticosteroids and of mycophenolate is limited and there is little firm evidence for a beneficial effect of methotrexate, penicillamine, thalidomide or colchicine. Other treatments being evaluated include fibric acid derivatives (fibrates), NSAIDs and leukotriene antagonists. Liver transplantation remains the only option for end-stage disease but recurrence of disease may be found in the graft. Experimental therapies include antiretroviral therapy. Symptomatic treatment is required for pruritus and the mainstays are the bile acid binding agents such as colestyramine. For those who are intolerant of the drug or where it is ineffective, rifampicin and naltrexone may be effective. There is no effective treatment for the associated lethargy.

Tauroursodeoxycholic acid protects rat hepatocytes from bile acid-induced apoptosis via activation of survival pathways

Ursodeoxycholic acid (UDCA) is used in the treatment of cholestatic liver diseases, but its mechanism of action is not yet well defined. The aim of this study was to explore the protective mechanisms of the taurine-conjugate of UDCA (tauroursodeoxycholic acid [TUDCA]) against glycochenodeoxycholic acid (GCDCA)-induced apoptosis in primary cultures of rat hepatocytes. Hepatocytes were exposed to GCDCA, TUDCA, the glyco-conjugate of UDCA (GUDCA), and TCDCA. The phosphatidylinositol-3 kinase pathway (PI3K) and nuclear factor-kappaB were inhibited using LY 294002 and adenoviral overexpression of dominant-negative IkappaB, respectively. The role of p38 and extracellular signal-regulated protein kinase mitogen-activated protein kinase (MAPK) pathways were investigated using the inhibitors SB 203580 and U0 126 and Western blot analysis. Transcription was blocked by actinomycin-D. Apoptosis was determined by measuring caspase-3, -9, and -8 activity using fluorimetric enzyme detection, Western blot analysis, immunocytochemistry, and nuclear morphological analysis. Our results demonstrated that uptake of GCDCA is needed for apoptosis induction. TUDCA, but not TCDCA and GUDCA, rapidly inhibited, but did not delay, apoptosis at all time points tested. However, the protective effect of TUDCA was independent of its inhibition of caspase-8. Up to 6 hours of preincubation with TUDCA before addition of GCDCA clearly decreased GCDCA-induced apoptosis. At up to 1.5 hours after exposure with GCDCA, the addition of TUDCA was still protective. This protection was dependent on activation of p38, ERK MAPK, and PI3K pathways, but independent of competition on the cell membrane, NF-kappaB activation, and transcription. In conclusion, TUDCA contributes to the protection against GCDCA-induced mitochondria-controlled apoptosis by activating survival pathways.

Toxicity of ethanol and acetaldehyde in hepatocytes treated with ursodeoxycholic or tauroursodeoxycholic acid

In hepatocytes ethanol (EtOH) is metabolized to acetaldehyde and to acetate. Ursodeoxycholic acid (UDCA) and tauroursodeoxycholic acid (TUDCA) are said to protect the liver against alcohol. We investigated the influence of ethanol and acetaldehyde on alcohol dehydrogenase (ADH)-containing human hepatoma cells (SK-Hep-1) and the protective effects of UDCA and TUDCA (0.01 and 0.1 mM). Cells were incubated with 100 and 200 mM ethanol, concentrations in a heavy drinker, or acetaldehyde. Treatment with acetaldehyde or ethanol resulted in a decrease of metabolic activity and viability of hepatocytes and an increase of cell membrane permeability. During simultaneous incubation with bile acids, the metabolic activity was better preserved by UDCA than by TUDCA. Due to its more polar character, acetaldehyde mostly damaged the superficial, more polar domain of the membrane. TUDCA reduced this effect, UDCA was less effective. Damage caused by ethanol was smaller and predominantly at the more apolar site of the cell membrane. In contrast, preincubation with TUDCA or UDCA strongly decreased metabolic activity and cell viability and led to an appreciable increase of membrane permeability. TUDCA and UDCA only in rather high concentrations reduce ethanol and acetaldehyde-induced toxicity in a different way, when incubated simultaneously with hepatocytes. In contrast, preincubation with bile acids intensified cell damage. Therefore, the protective effect of UDCA or TUDCA in alcohol- or acetaldehyde-treated SK-Hep-1 cells remains dubious.

Ursodeoxycholic acid protects against secondary biliary cirrhosis in rats by preventing mitochondrial oxidative stress

Ursodeoxycholic acid (UDCA) improves clinical and biochemical indices in primary biliary cirrhosis and prolongs survival free of liver transplantation. Recently, it was suggested that the cytoprotective mechanisms of UDCA may be mediated by protection against oxidative stress, which is involved in the development of cirrhosis induced by chronic cholestasis. The aims of the current study were 1) to identify the mechanisms involved in glutathione depletion, oxidative stress, and mitochondrial impairment during biliary cirrhosis induced by chronic cholestasis in rats; and 2) to determine the mechanisms associated with the protective effects of UDCA against secondary biliary cirrhosis. The findings of the current study indicate that UDCA partially prevents hepatic and mitochondrial glutathione depletion and oxidation resulting from chronic cholestasis. Impairment of biliary excretion was accompanied by decreased steady-state hepatic levels of gamma-glutamyl cysteine synthetase and gamma-cystathionase messenger RNAs. UDCA treatment led to up-regulation of gamma-glutamyl cysteine synthetase in animals with secondary biliary cirrhosis and prevented the marked increases in mitochondrial peroxide production and hydroxynonenal-protein adduct production that are observed during chronic cholestasis. A population of damaged and primarily apoptotic hepatocytes characterized by dramatic decreases in mitochondrial cardiolipin levels and membrane potential as well as phosphatidylserine exposure evolves in secondary biliary cirrhosis. UDCA treatment prevents the growth of this population along with the decreases in mitochondrial cardiolipin levels and membrane potential that are induced by chronic cholestasis. In conclusion, UDCA treatment enhances the antioxidant defense mediated by glutathione; in doing so, this treatment prevents cardiolipin depletion and cell injury in animals with secondary biliary cirrhosis.

Mechanisms of action and therapeutic efficacy of ursodeoxycholic acid in cholestatic liver disease

Ursodeoxycholic acid (UDCA) is widely used for the treatment of cholestatic liver diseases. Multiple mechanisms of action of UDCA have been described aiming at one or more of the pathogenetic processes of cholestatic liver diseases: (1) protection of injured cholangiocytes against toxic effects of bile acids, (2) stimulation of impaired biliary secretion, (3) stimulation of detoxification of hydrophobic bile acids, and (4) inhibition of apoptosis of hepatocytes. Through one or more of these mechanisms, UDCA slows the progression of primary biliary cirrhosis and improves a number of other cholestatic disorders.

Protective effects of ursodeoxycholic acid against 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced testicular damage in mice

The protective effect of ursodeoxycholic acid (UDCA), a biliary component found in bears, on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced testicular damage in mice was investigated. Fifty C57BL/6J mice were equally divided into five groups. The mice in the control group received the vehicle and standard chow. The single TCDD treatment group received 27.5 microg/kg of TCDD subcutaneously. The UDCA-included treatment group received pulverized chow containing 0.125%, 0.25% and 0.5% UDCA, respectively, for 70 days starting 10 days before TCDD injections. The body and testicular weights were shown to be decreased in the single TCDD treatment group, while the decrease was prevented by UDCA added to the chow. In addition, the decrease in the serum-luteinizing hormone (LH) or the follicle stimulating hormone (FSH) secondary to a TCDD injection was not observed in the UDCA-included treatment group. Contrary to the single TCDD treatment group, the germinal epithelium and intercellular space were relatively well preserved in the UDCA-included treatment group. Adding UDCA also normalized TCDD-induced irregular ultrastructural changes such as development of phagolysosomes, inflated smooth endoplasmic reticulum (SER), dilated and altered mitochondria, necrosis and completely damaged seminiferous tubules. Moreover, in the experiment for Arnt expression, UDCA added to the chow suppressed the TCDD-induced relocation of Arnt from the cytoplasm to the nuclei. In conclusion, TCDD-induced testicular toxicity was effectively protected by UDCA. There was almost complete recovery of the testes in the UDCA-included treatment group. Thus, UDCA may be useful for the prevention and treatment of TCDD-induced testicular damage.

Involvement of integrins and Src in tauroursodeoxycholate-induced and swelling-induced choleresis

BACKGROUND & AIMS

Stimulation of canalicular secretion by tauroursodeoxycholate (TUDC) involves dual activation of p38 mitogen-activated protein kinase (p38(MAPK)) and extracellular signal-regulated kinase (ERK). This study investigates the sensing and upstream signaling events of TUDC-induced choleresis.

METHODS

TUDC and hypo-osmolarity effects on protein kinase activities and taurocholate excretion were studied in perfused rat liver.

RESULTS

TUDC induced a rapid activation of focal adhesion kinase (FAK) and Src, as shown by an increase in Y418 phosphorylation and a decrease in Y529 phosphorylation of Src. Inhibition of Src by PP-2 abolished the TUDC-induced activation of p38(MAPK) but not of FAK and ERKs. An integrin-inhibitory peptide with an RGD motif blocked TUDC-induced FAK, Src, ERK, and p38(MAPK) activation, suggesting that integrin signaling toward FAK/Src is required for TUDC-induced MAPK activation. The RGD peptide and PP-2 also abolished the stimulation of taurocholate excretion in perfused rat liver in response to TUDC. Integrin-dependent Src activation was also identified as an upstream event in hypo-osmotic signaling toward MAPKs and choleresis.

CONCLUSIONS

TUDC-induced stimulation of canalicular taurocholate excretion involves integrin sensing, FAK, and Src activation as upstream events for dual MAPK activation. Integrins may also represent one long-searched sensor for cell hydration changes in response to hypo-osmolarity.

Epidemiology and prevention of colorectal cancer

CRC, the second-leading cause of cancer death in the United States, is a highly preventable disease. Ironically, available and effective screening technologies are not consistently applied, even as new ones are developed. This discordance between preventive opportunity and practice conveys a sobering message regarding nontechnologic issues that must be addressed if the promise of CRC prevention is to be realized. Our response to this message will determine the public health impact of cancer prevention. In the 1980s, cancer chemoprevention was regarded as scientific speculation. Within the last decade, however, cancer has been recognized as a late, nonobligate stage of carcinogenesis, a chronic process that provides time and targets for preventive intervention. Further advances are emerging out of rigorous clinical testing, which remains the limiting factor in transforming ingenious concepts into useful tools for the prevention of CRC. The challenges and rewards of participation in chemoprevention research--both as patients and health care providers-have never been greater.

Ursodeoxycholic acid for the prevention of hepatic complications in allogeneic stem cell transplantation

The role of ursodeoxycholic acid (UDCA) in the prevention of hepatic complications after allogeneic stem cell transplantation was studied in a prospective randomized open-label multicenter trial. A total of 242 patients were allocated to receive (n = 123) or not to receive (n = 119) UDCA in the dose of 12 mg/kg/d orally from the day preceding the conditioning until day 90 after transplantation. In the UDCA-treated group a significantly smaller proportion of patients developed a serum bilirubin level exceeding 50 microM (18 of 123 versus 31 of 119, P =.04), and similarly a smaller proportion of patients exceeded the alanine aminotransferase level of 100 U/L. There was no difference in the incidence of veno-occlusive disease of the liver. Compared to the control group, in the UDCA-treated group there was a nonsignificant trend toward a lower overall incidence of acute graft-versus-host disease (GVHD) and a significantly lower incidence of grade III to IV acute GVHD (5 of 123 versus 17 of 119, P =.01), stage II to IV liver and intestinal GVHD, and stage III to IV skin GVHD. There was no difference in the incidence of chronic GVHD or in the relapse rate. Among the patients given UDCA, the survival at 1 year was significantly better, 71% versus 55% (P =.02), and the nonrelapse mortality rate was lower, 19% versus 34% (P =.01), than in the control group. There were significantly more deaths in GVHD in the control group. In conclusion, UDCA administration reduced hepatic problems and severe acute GVHD and improved survival. These results suggest a role for UDCA in the prevention of transplant-related complications in allogeneic transplantation.