Effect of ursodeoxycholic acid on methionine adenosyltransferase activity and hepatic glutathione metabolism in rats

UDCA for Drug-Induced Liver Disease: Clinical and Pathophysiological Basis

Drug-induced liver injury (DILI) is an adverse reaction to medications and other xenobiotics that leads to liver dysfunction. Based on differential clinical patterns of injury, DILI is classified into hepatocellular, cholestatic, and mixed types; although hepatocellular DILI is associated with inflammation, necrosis, and apoptosis, cholestatic DILI is associated with bile plugs and bile duct paucity. Ursodeoxycholic acid (UDCA) has been empirically used as a supportive drug mainly in cholestatic DILI, but both curative and prophylactic beneficial effects have been observed for hepatocellular DILI as well, according to preliminary clinical studies. This could reflect the fact that UDCA has a plethora of beneficial effects potentially useful to treat the wide range of injuries with different etiologies and pathomechanisms occurring in both types of DILI, including anticholestatic, antioxidant, anti-inflammatory, antiapoptotic, antinecrotic, mitoprotective, endoplasmic reticulum stress alleviating, and immunomodulatory properties. In this review, a revision of the literature has been performed to evaluate the efficacy of UDCA across the whole DILI spectrum, and these findings were associated with the multiple mechanisms of UDCA hepatoprotection. This should help better rationalize and systematize the use of this versatile and safe hepatoprotector in each type of DILI scenarios.

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.

Ursodeoxycholate Restores Biliary Excretion of Methotrexate in Rats with Ethinyl Estradiol Induced-Cholestasis by Restoring Canalicular Mrp2 Expression

The in vivo relevance of ursodeoxycholate (UDCA) treatment (100 mg/kg/day, per oral tid for 5 days before cholestasis induction followed by the same dosing for 5 days) on hepatic function was investigated in rats with 17α-ethinylestradiol (EE, 10 mg/kg, subcutaneous for 5 days)-induced experimental cholestasis. The bile flow rate and the expression level of hepatic multidrug resistance-associated protein 2 (Mrp 2) that were decreased in cholestasis were restored after UDCA treatment. Consistent with this, the biliary excretion clearance (CL_exc,bile) of a representative Mrp2 substrate—methotrexate (MTX)—was decreased in cholestatic rats but was restored after UDCA treatment. Consequently, the plasma concentrations of MTX, which were increased by cholestasis, were decreased to control levels by UDCA treatment. Thus, the restoration of CL_exc,bile appears to be associated with the increase in Mrp2 expression on the canalicular membrane by UDCA treatment followed by Mrp2-mediated biliary excretion of MTX. On the other hand, the hepatic uptake clearance (CL_up,liver) of MTX was unchanged by cholestasis or UDCA treatment, suggestive of the absence of any association between the uptake process and the overall biliary excretion of MTX. Since UDCA has been known to induce the expression of canalicular MRP2 in humans, UDCA treatment might be effective in humans to maintain or accelerate the hepatobiliary elimination of xenobiotics or metabolic conjugates that are MRP2 substrates.

Primary Biliary Cholangitis: Disease Pathogenesis and Implications for Established and Novel Therapeutics

Primary Biliary Cholangitis is a progressive, autoimmune cholestatic liver disorder. Cholestasis with disease progression may lead to dyslipidemia, osteodystrophy and fat-soluble vitamin deficiency. Portal hypertension may develop prior to advanced stages of fibrosis. Untreated disease may lead to cirrhosis, hepatocellular cancer and need for orthotopic liver transplantation. Classically, diagnosis is made with elevation of alkaline phosphatase, demonstration of circulating antimitochondrial antibody, and if performed: asymmetric destruction/nonsupperative cholangitis of intralobular bile ducts on biopsy. Disease pathogenesis is complex and results from innate and adaptive (cell-mediated and humoral) responses that lead to inflammation of biliary duct epithelium. Ongoing damage is amplified and sustained through bile acid toxicity. Use of weight based (13-15mg/kg) ursodeoxycholic acid is well established in retarding disease progression and improving survival; however, is ineffective in achieving complete biochemical remission in many. Recently, a Farnesoid X Receptor agonist, obeticholic acid, has been approved for use. A number of ongoing clinical studies are underway to evaluate utility of fibric acid derivatives, biologics, antifibrotics, and stem cells as monotherapy or in combination with ursodeoxycholic acid for primary biliary cholangitis. The aim of this review is to discuss disease pathogenesis and highlight rationale/implications for both established and novel therapeutics.

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.

Ursodeoxycholic acid decreases sodium-glucose cotransporter (SGLT2) expression and oxidative stress in the kidney of diabetic rats

Oxidative stress has been associated with diabetic complications like nephropathies. Recent studies indicate that ursodeoxycholic acid (UDCA) may be beneficial preventing diabetes-induced oxidative stress and secondary complications. Thus, we study if the UDCA-treatment decreases the expression of sodium-glucose cotransporter (SGLT2) and the oxidative stress in the kidney of diabetic rats.

METHODS

The diabetes model was established by intraperitoneal injection of streptozotocin (50mg/kg). SGLT2 expression was evaluated by western blot and RT-PCR. Oxidative stress was assessed by catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase activities (SOD) and immunohistochemical analysis of 3-nitrotyrosine (3-NT).

RESULTS

Streptozotocin-induced diabetes caused hyperglycemia and lower body weight. The SGLT2 expression and mRNA levels increased in cortex of kidney from diabetic rats. The CAT activity decreased in cortex and medulla from diabetic rats, otherwise the GPx activity increased. Furthermore the 3-NT staining of kidney from diabetic rats increased compared to control rats. The UDCA treatment was able to decrease hyperglycemia and prevents the SGLT2 over-expression, restores the CAT and GPX activities and decreases 3-NT staining.

CONCLUSION

The UDCA treatment prevents the over-expression of SGLT2 and oxidative stress in kidney of diabetic rats.

Biliary secretion of S-nitrosoglutathione is involved in the hypercholeresis induced by ursodeoxycholic acid in the normal rat

Ursodeoxycholic acid (UDCA) induces bicarbonate-rich hypercholeresis by incompletely defined mechanisms that involve the stimulation of adenosine triphosphate (ATP) release from cholangiocytes. As nitric oxide (NO) at a low concentration can stimulate a variety of secretory processes, we investigated whether this mediator could be implicated in the choleretic response to UDCA. Our in vivo experiments with the in situ perfused rat liver model in anesthetized rats, showed that UDCA infusion increased the biliary secretion of NO derivatives, hepatic inducible NO synthase expression, and NO synthase activity in liver tissue. UDCA also stimulated NO release by isolated rat hepatocytes. In contrast to UDCA, cholic acid was a poor inducer of NO secretion, and tauroursodeoxycholic acid showed no effect on NO secretion. Upon UDCA administration, NO was found in bile as low-molecular-weight nitrosothiols, of which S-nitrosoglutathione (GSNO) was the predominant species. UDCA-stimulated biliary NO secretion was abolished by the inhibition of inducible NO synthase with N(omega)-nitro-L-arginine methyl ester in isolated perfused livers and also in rats whose livers were depleted of glutathione with buthionine sulfoximine. Moreover, the biliary secretion of NO species was significantly diminished in UDCA-infused transport mutant [ATP-binding cassette C2 (ABCC2)/multidrug resistance-associated protein 2 (Mrp2)-deficient] rats, and this finding was consistent with the involvement of the glutathione carrier ABCC2/Mrp2 in the canalicular transport of GSNO. It was particularly noteworthy that in cultured normal rat cholangiocytes, GSNO activated protein kinase B, protected against apoptosis, and enhanced UDCA-induced ATP release to the medium; this effect was blocked by phosphoinositide 3-kinase inhibition. Finally, retrograde GSNO infusion into the common bile duct increased bile flow and biliary bicarbonate secretion.

CONCLUSION

UDCA induces biliary secretion of GSNO, which contributes to stimulating ductal secretion.

Bilirubin selectively inhibits cytochrome c oxidase activity and induces apoptosis in immature cortical neurons: assessment of the protective effects of glycoursodeoxycholic acid

High levels of unconjugated bilirubin (UCB) may initiate encephalopathy in neonatal life, mainly in pre-mature infants. The molecular mechanisms of this bilirubin-induced neurologic dysfunction (BIND) are not yet clarified and no neuroprotective strategy is currently worldwide accepted. Here, we show that UCB, at conditions mimicking those of hyperbilirubinemic newborns (50 microM UCB in the presence of 100 muM human serum albumin), rapidly (within 1 h) inhibited cytochrome c oxidase activity and ascorbate-driven oxygen consumption in 3 days in vitro rat cortical neurons. This was accompanied by a bioenergetic and oxidative crisis, and apoptotic cell death, as judged by the collapse of the inner-mitochondrial membrane potential, increased glycolytic activity, superoxide anion radical production, and ATP release, as well as disruption of glutathione redox status. Furthermore, the antioxidant compound glycoursodeoxycholic acid (GUDCA) fully abrogated UCB-induced cytochrome c oxidase inhibition and significantly prevented oxidative stress, metabolic alterations, and cell demise. These results suggest that the neurotoxicity associated with neonatal bilirubin-induced encephalopathy occur through a dysregulation of energy metabolism, and supports the notion that GUDCA may be useful in the treatment of BIND.

The effect of ursodeoxycholic acid on liver regeneration after partial hepatectomy in rats with non-alcoholic fatty liver disease

AIM

To investigate the effect of ursodeoxycholic acid (UDCA) on liver regeneration following partial hepatectomy in rats with non-alcoholic fatty liver disease (NAFLD).

METHODS

UDCA was administered to seven rats (group 1) and physiological saline was administered both to seven rats (group 2) with NAFLD and to seven rats with normal livers (group 3). All rats underwent two-thirds hepatectomy and the remnant liver tissues were removed 48 h later. Mitotic index (MI) and levels of proliferating cell nuclear antigen (PCNA), glutathione (GSH) and malondialdehyde (MDA) were assayed.

RESULTS

MI and PCNA levels in group 2 were significantly lower than in groups 1 and 3, but the values in groups 1 and 3 were similar. The GSH levels of group 2 were significantly lower than those of group 3 in the hepatectomy tissues, and lower than those of groups 1 and 3 in the remnant tissues. The differences between GSH levels in groups 1 and 3 were not significant. MDA levels in hepatectomy and remnant tissues were significantly higher in group 2 compared to groups 1 and 3; values in groups 1 and 3 were similar.

CONCLUSION

UDCA increases regeneration after partial hepatectomy in rats with NAFLD, possibly due to an attenuating effect on oxidative stress.

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.

Chronic administration of ursodeoxycholic acid decreases portal pressure in rats with biliary cirrhosis

Liver cirrhosis is characterized by increased IHR (intrahepatic resistance) and lipid peroxidation, and decreased antioxidative defence. The present study investigates the effects of administration for 1 month of the antioxidant UDCA (ursodeoxycholic acid) in BDL (bile-duct-ligated) cirrhotic rats. Splanchnic haemodynamics, IHR, hepatic levels of TBARS (thiobarbituric acid-reacting substances), GSH (glutathione), SOD (superoxide dismutase) activity, nitrite, PIIINP (N-terminal propeptide of type III procollagen) and collagen deposition, histological examination of liver, mRNA expression of PIIIP-alpha1 (type III procollagen) and TGF-beta1 (transforming growth factor-beta1), protein expression of TXS (thromboxane synthase) and iNOS (inducible NO synthase), and TXA2 (thromboxane A2) production in liver perfusates were measured. The results showed that portal pressure and IHR, hepatic levels of PIIINP, hepatic collagen deposition, mRNA expression of PIIIP-alpha1 and TGF-beta1, protein expression of iNOS and TXS, and production of TXA2 in liver perfusates were significantly decreased in UDCA-treated BDL rats. The increased levels of hepatic GSH and SOD activity and decreased levels of TBARS and nitrite were also observed in UDCA-treated BDL rats. In UDCA-treated BDL rats, the reduction in portal pressure resulted from a decrease in IHR, which mostly acted through the suppression of hepatic TXA2 production and lipid peroxidation, and an increase in antioxidative defence, leading to the prevention of hepatic fibrosis.

Ursodeoxycholic acid stimulates Nrf2-mediated hepatocellular transport, detoxification, and antioxidative stress systems in mice

The protective action of ursodeoxycholic acid (UDCA) in cholestatic liver diseases may be mediated by choleresis, detoxification, and cytoprotection against oxidative stress. Nrf2, one transcription factor, serves as a cellular stress sensor and is a key regulator for hepatic induction of detoxifying enzymes, antioxidative stress genes, and numerous Mrp family members. We aimed to investigate whether UDCA induces hepatic Mrp expression along with that of detoxifying enzymes and antioxidative stress genes via the Nrf2 transcriptional pathway. The protein level, subcellular localization, and mRNA level of Mrp family members were assessed in livers of Keap1 gene-knockdown (Keap1-kd) mice and those of UDCA-fed wild-type (WT) and Nrf2 gene-null (Nrf2-null) mice. Nuclear levels of Nrf2 in livers of Keap1-kd mice markedly increased, resulting in constitutive activation of Nrf2. Keap1-kd mice have high-level expression of hepatic Mrp2, Mrp3, and Mrp4 relative to WT mice. UDCA potently increased nuclear Nrf2 expression level in livers of WT mice, and the treatment showed maximal hepatic induction of Mrp2, Mrp3, and Mrp4 in association with enhanced membranous localizations in an Nrf2-dependent manner. UDCA similarly increased nuclear Nrf2 expression level in rat hepatocytes. Chromatin immunoprecipitation assays using mouse hepatocytes revealed the binding of Nrf2 to antioxidant response elements in the promoter regions of Mrp2, Mrp3, and Mrp4. These findings demonstrate an important role of Nrf2 in the induction of Mrp family members in livers and suggest that a therapeutic mechanism of UDCA action is, via Nrf2 activation, a stimulation of detoxification and antioxidative stress systems, along with Mrp-mediated efflux transport.

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

BACKGROUND

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Ursodeoxycholic acid and superoxide anion

AIM: To investigate the ability of ursodeoxycholic acid (UDCA) to scavenge superoxide anion (O2^-).

METHODS: We assessed the ability of UDCA to scavenge (O2^-) generated by xanthine-xanthine oxidase (X-XO) in a cell-free system and its effect on the rate of O2^--induced ascorbic acid (AA) oxidation in hepatic post-mitochondrial supernatants.

RESULTS: UDCA at a concentration as high as 1 mmol/L did not impair the ability of the X-XO system to generate O2^-, but could scavenge O2^- at concentrations of 0.5 and 1 mmol/L, and decrease the rate of AA oxidation at a concentration of 100 µmol/L.

CONCLUSION: UDCA can scavenge O2^-, an action that may be beneficial to patients with primary biliary cirrhosis.

Oxidative Stress in Nonalcoholic Fatty Liver Disease: Pathogenesis and Antioxidant Therapies

Nonalcoholic fatty liver disease is a common cause of chronic liver disease, a common finding on liver biopsy in those patients with abnormal blood transaminase levels, and a common cause of cryptogenic cirrhosis in the United States. The prevalence of this disorder is expected to rise with the increase in obesity, and the clinical spectrum can range from simple steatosis (fatty liver) to cirrhosis of the liver. Insulin resistance is thought to be pivotal for the development of steatosis, and oxidative stress may be a potential factor that can promote hepatic necroinflammation and fibrosis. Preliminary studies have examined the role of oxidative stress and antioxidants in animal and human studies of this disorder. Efforts to improve the hepatic antioxidant system could be achieved by optimizing the patient's diet, by supplementation with precursors for antioxidants, or by supplementation with essential metals and/or antioxidants. Randomized, controlled trials are required to examine these potential approaches using patients with this disorder.

Chronic hepatitis in dogs: a review of current understanding of the aetiology, progression, and treatment

Chronic hepatitis is common in dogs in primary and referral practice but the cause is usually unknown. This paper reviews the literature on potential causes of chronic hepatitis in dogs (infectious, autoimmune, metabolic, toxic, and breed-associated) together with the literature on the progression of the disease and on treatments. This is compared with the current understanding of aetiology, progression, and treatment of chronic hepatitis in man. Unfortunately, little is known about the aetiology and progression of the canine disease and very few therapies have been subjected to critical trials. It is difficult therefore to draw conclusions about causes and effective treatment in dogs. Even the histological description for canine chronic hepatitis has yet to be standardised. Much research remains to be done and this review suggests some potential areas for future investigation.

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.

Cholestatic syndromes

Further insights into the cellular and molecular mechanisms underlying hepatobiliary transport function and its regulation now permit a better understanding of the pathogenesis and treatment options of cholestatic liver diseases. Identification of the molecular basis of hereditary cholestatic syndromes will result in an improved diagnosis and management of these conditions. New insights into the pathogenesis of extrahepatic manifestations of cholestasis (eg, pruritus) have facilitated new treatment strategies. Important new studies have been published about the pathogenesis, clinical features, diagnosis, and treatment of primary biliary cirrhosis, primary sclerosing cholangitis, cholestasis of pregnancy, total parenteral nutrition-induced cholestasis, drug-induced cholestasis, and viral cholestatic syndromes.