Resveratrol and liver disease: from bench to bedside and community

Liver diseases incorporate several maladies, which can range from benign histological changes to serious life‐threatening conditions. These may include inborn metabolic disease, primary and metastatic cancers, alcoholic cirrhosis, viral hepatitis and drug‐induced hepatotoxicity. Liver disease remains a major cause of morbidity and mortality with significant economic and social costs. Several novel approaches are currently being studied which may provide a better therapeutic outcome. The use of naturally occurring phytochemicals, some of them obtained from dietary sources, in the amelioration of illness have recently gained considerable popularity. These agents, having anti‐oxidant and anti‐inflammatory properties, provide a safe and effective means of ameliorating chronic disease. Resveratrol, a grape polyphenol, has shown considerable promise as a therapeutic agent in the treatment of the aforementioned liver ailments. Several studies have highlighted the hepatoprotective properties of resveratrol. Resveratrol has been shown to prevent hepatic damage because of free radicals and inflammatory cytokines, induce anti‐oxidant enzymes and elevate glutathione content. Resveratrol has also been shown to modulate varied signal transduction pathways implicated in liver diseases. This review critically examines the current preclinical in vitro and in vivo studies on the preventive and therapeutic effects of resveratrol in liver diseases. The review highlights the pharmacological mechanisms involved in mediating the aforementioned effects. Toxicity, pharmacokinetics and clinical bioavailability of resveratrol are also reviewed in this article. The challenges involved, future directions and novel approaches such as site‐specific drug delivery in the use of resveratrol for the prevention and treatment of liver disease are also discussed.     

Oxidative stress and hippocampus in a low‐grade hepatic encephalopathy model: protective effects of curcumin

Aim: The present study was performed on prehepatic portal hypertensive rats, a model of low‐grade hepatic encephalopathy, designed to evaluate whether oxidative stress was a possible pathway implicated in hippocampal damage and if so, the effect of an anti‐oxidant to prevent it. Methods: Prehepatic portal hypertension was induced by a regulated portal vein stricture. Oxidative stress was investigated by assessing related biochemical parameters in rat hippocampus. The effect of the anti‐oxidant curcumin, administered in a single i.p. dose of 100 mg/kg on the seventh, ninth and eleventh days after surgery, was evaluated. Results: Oxidative stress in the rat hippocampal area was documented. Curcumin significantly decreased tissue malondialdehyde levels and significantly increased glutathione peroxidase, catalase and superoxide dismutase activities in the hippocampal tissue of portal hypertensive rats. Conclusion: Oxidative stress was found to be implicated in the hippocampal damage and curcumin protected against this oxidative stress in low‐grade hepatic encephalopathic rats. These protective effects may be attributed to its anti‐oxidant properties.     

Curcumin downregulates Smad pathways and reduces hepatic stellate cells activation in experimental fibrosis

Introduction and ObjectivesCurcumin, a polyphenol, is a natural compound that has been widely studied as a hepatoprotector; however, only a few studies have examined its ability to reduce fibrosis in previously established cirrhosis. The objective of this study was to investigate whether curcumin could reduce carbon tetrachloride (CCl₄)-induced fibrosis and if so, to determine the action mechanisms involved in the reduction process.Materials and MethodsCCl₄ was administered to male Wistar rats (400 mg/kg, three times a week, i. p.) for 12 weeks; curcumin (100 mg/kg body weight twice per day, p. o.) was administered from week 9–12 of CCl₄ treatment. Biochemical markers of hepatic injury and oxidative stress were evaluated. Hematoxylin and eosin, Masson’s trichrome stains, transmission electron microscopy; immunohistochemistry, and zymography assays were carried out. Moreover, Smad3 and α-SMA mRNA and protein levels were studied. Western blotting by TGF-β, CTGF, Col-I, MMP-13, NF-κB, IL-1, IL-10, Smad7, pSmad3, and pJNK proteins was developed.Results and ConclusionsCurcumin reduced liver damage, oxidative stress, fibrosis, and restored normal activity of MMP-9 and MMP-2. Besides, curcumin restored NF-κB, IL-1, IL-10, TGF-β, CTGF, Col-I, MMP-13, and Smad7 protein levels. On the other hand, curcumin decreased JNK and Smad3 phosphorylation. Furthermore, curcumin treatment decreased α-SMA and Smad3 protein and mRNA levels. Curcumin normalized GSH, and NF-κB, JNK-Smad3, and TGF-β-Smad3 pathways, leading to a decrement in activated hepatic stellate cells, thereby producing its antifibrotic effects.     

Antifibrotic and fibrolytic properties of celecoxib in liver damage induced by carbon tetrachloride in the rat

Background: Transforming growth factor‐β (TGF‐β) plays a pivotal role in liver fibrosis, because it activates hepatic stellate cells, stimulating extracellular matrix deposition. Cyclooxygenase‐2 (COX‐2) has been associated with TGF‐β because its inhibition decreases TGF‐β expression and collagen production in some cultured cell types. Aim: The aim of this work was to evaluate the ability of celecoxib (a selective COX‐2 inhibitor) to prevent and to reverse the liver fibrosis induced by CCl₄. Methods: We established experimental groups of rats including vehicle and drug controls, damage induced by chronic CCl₄ administration and CCl₄ plus pharmacological treatment in both prevention and reversion models. We determined: alanine aminotransferase, alkaline phosphatase, γ‐glutamyl transpeptidase, COX and metalloproteinase‐2 and ‐9 activities, lipid peroxidation, glutathione levels, glycogen and collagen content and TGF‐β expression. Results: Celecoxib prevented and aided to the recovery of livers with necrotic and cholestatic damage. Celecoxib exhibited anti‐oxidant properties by restoring the redox equilibrium (lipid peroxidation and glutathione levels). Glycogen was decreased by CCl₄, while celecoxib partially prevented and reversed this effect. Celecoxib inhibited COX‐2 activity, decreased TGF‐β expression, induced metalloproteinase‐2 activity and, consequently, prevented and reversed collagen accumulation. Conclusion: Our findings indicate that celecoxib exerts strong antifibrogenic and fibrolytic effects in the CCl₄ model of cirrhosis.     

(Z)2-(5-(4-methoxybenzylidene)-2, 4-dioxothiazolidin-3-yl) acetic acid protects rats from CCl(4) -induced liver injury

Background and Aim: (Z)2‐(5‐(4‐methoxybenzylidene)‐2, 4‐dioxothiazolidin‐3‐yl) acetic acid (MDA) is an aldose reductase (AR) inhibitor. Recent studies suggest that AR contributes to the pathogenesis of inflammation by affecting the nuclear factor κB (NF‐κB)‐dependent expression of cytokines and chemokines and therefore could be a novel therapeutic target for inflammatory pathology. The current study evaluated the in vivo role of MDA in protecting the liver against injury and fibrogenesis caused by CCl₄ in rats, and the underlying mechanisms. Methods: A single injection of CCl₄ induced acute hepatitis, and repeated injections were used to induce hepatic fibrosis in rats. Therapeutic efficacy was assessed by comparison of the severity of hepatic injury and fibrosis in MDA ‐ treated rats versus untreated controls. Results: MDA significantly protected the liver from injury by reducing the activity of serum alanine aminotransferase, and improving the histological architecture of the liver. MDA modulated NF‐κB‐dependent activation of inflammatory cytokines by reducing hepatic mRNA levels of tumor necrosis factor‐α, interleukin‐1β, inducible nitric oxide (NO) synthase and transforming growth factor‐β. In addition, MDA attenuated oxidative stress by increasing the content of hepatic glutathione. These favorable changes were associated with suppressed hepatic NF‐κB activation by MDA. MDA treatment improved liver fibrosis in rats that received repeated CCl₄ injections. In vitro, MDA attenuated phosphorylation of IκB and activation of NF‐κB, and thus prevented biosynthesis of NO in lipopolysaccharide‐activated RAW264.7 cells. Conclusions: The present study suggests that AR is a novel therapeutic anti‐inflammatory target for the treatment of hepatitis and liver fibrosis.     

Therapeutic potential of curcumin in gastrointestinal diseases

Curcumin,also known as diferuloylmethane,is derived from the plant Curcuma longa and is the active ingredient of the spice turmeric.The therapeutic activities of curcumin for a wide variety of diseases such as diabetes,allergies,arthritis and other chronic and inflammatory diseases have been known for a long time.More recently,curcumin’s therapeutic potential for preventing and treating various cancers is being recognized.As curcumin’s therapeutic promise is being explored more systematically in various diseases,it has become clear that,due to its increased bioavailability in the gastrointestinal tract,curcumin may be particularly suited to be developed to treat gastrointestinal diseases.This review summarizes some of the current literature of curcumin’s anti-inflammatory,anti-oxidant and anti-cancer potential in inflammatory bowel diseases,hepaticfibrosis and gastrointestinal cancers.     

Therapeutic potential of curcumin in digestive diseases

Curcumin is a low-molecular-weight hydrophobic polyphenol that is extracted from turmeric,which possesses a wide range of biological properties including anti-inflammatory,anti-oxidant,anti-proliferative and anti-microbial activities.Despite its diverse targets and substantial safety,clinical applications of this molecule for digestive disorders have been largely limited to case series or small clinical trials.The poor bioavailability of curcumin is likely the major hurdle for its more widespread use in humans.However,complexation of curcumin into phytosomes has recently helped to bypass this problem,as it has been demonstrated that this new lecithin formulation enables increased absorption to a level 29-fold higher than that of traditional curcuminoid products.This allows us to achieve much greater tissue substance delivery using significantly lower doses of curcumin than have been used in past clinical studies.As curcumin has already been shown to provide good therapeutic results in some small studies of both inflammatory and neoplastic bowel disorders,it is reasonable to anticipate an even greater efficacy with the advent of this new technology,which remarkably improves its bioavailability.These features are very promising and may represent a novel and effective therapeutic approach to both functional and organic digestive diseases.     

Cytokine blockade inhibits hepatic tissue inhibitor of metalloproteinase‐1 expression and up‐regulates matrix metalloproteinase‐9 in toxic liver injury

Abstract: Background: Tissue inhibitor of metalloproteinases (TIMP)‐1, the most important endogenous inhibitor of matrix metalloproteinases, plays a pivotal role in the pathogenesis of liver fibrosis and may represent an effective therapeutic target in the design of antifibrotic strategies for chronic liver diseases. Methods: Intraperitoneal application of a single dose of either tumor necrosis factor (TNF)‐α or interleukin (IL)‐1β in mice led to an enhanced expression of hepatic TIMP‐1 after 4–16 h. Male Sprague–Dawley rats were treated with carbon tetrachloride (CCl₄) in the presence and absence of specific TNF‐α and IL‐1β inhibitors. Results: Real‐time PCR revealed a significant increase of TIMP‐1 mRNA in total rat liver 24 h after CCl₄ injection. Repetitive injection of both, etanercept and anakinra, before and after CCl₄ injection effectively inactivated TNF‐α and IL‐1β. Anticytokine pretreatment reduced the increase of TIMP‐1 expression after a single CCl₄ injection by 50% and 75%, respectively. In contrast to CCl₄‐treated rats with and without TNF‐α blockade, IL‐1β inactivation caused a sevenfold increase in matrix metalloproteinases‐9 mRNA levels. Conclusions: In conclusion, TIMP‐1 expression is up‐regulated in the early phase of toxic liver injury by proinflammatory cytokines such as TNF‐α and IL‐1β in rodents. Pharmacological inactivation of these cytokines significantly reduces TIMP‐1 gene expression. Our data provide a potential new antifibrotic approach.     

Conditional knockout of heparin‐binding epidermal growth factor‐like growth factor in the liver accelerates carbon tetrachloride‐induced liver injury in mice

Aim: We previously demonstrated that heparin‐binding epidermal growth factor‐like growth factor (HB‐EGF) is induced in response to several liver injuries. Because the HB‐EGF knockout (KO) mice die in utero or immediately after birth due to cardiac defects, the loss of function study in vivo is limited. Here, we generated liver‐specific HB‐EGF conditional knockout mice using the interferon‐inducible Mx‐1 promoter driven cre recombinase transgene and investigated its role during acute liver injury. Methods: We induced acute liver injury by a single i.p. injection of carbon tetrachloride (CCl₄) in HB‐EGF KO mice and wild‐type mice and liver damage was assessed by biochemical and immunohistochemical analysis. We also used AML12 mouse hepatocyte cell lines to examine the molecular mechanism of HB‐EGF‐dependent anti‐apoptosis and wound‐healing process of the liver in vitro. Results: HB‐EGF KO mice exhibited a significant increase of alanine aminotransferase level and also showed a significant increase in the number of apoptotic hepatocytes assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling staining at 24 h after CCl₄ injection. We also demonstrated that HB‐EGF treatment inhibited tumor necrosis factor‐α‐induced apoptosis of AML12 mouse hepatocytes and promoted the wound‐healing response of these cells. Conclusion: This study showed that HB‐EGF plays a protective role during acute liver injury.     

Curcumin reduces the toxic effects of iron loading in rat liver epithelial cells

Background/Aims: Iron overload can cause liver toxicity and increase the risk of liver failure or hepatocellular carcinoma in humans. Curcumin (diferuloylmethane), a component of the food spice turmeric, has antioxidant, iron binding and hepatoprotective properties. The aim of this study was to quantify its effects on iron overload and the resulting downstream toxic effects in cultured T51B rat liver epithelial cells. Methods: T51B cells were loaded with ferric ammonium citrate (FAC) with or without the iron delivery agent 8‐hydroxyquinoline. Cytotoxicity was measured by methylthiazolyldiphenyl‐tetrazolium bromide assay. Iron uptake and iron bioavailability were documented by chemical assay, quench of calcein fluorescence and ferritin induction. Reactive oxygen species (ROS) were measured by a fluorescence assay using 2′,7′‐dichlorodihydrofluorescein diacetate. Oxidative stress signalling to jnk, c‐jun and p38 was measured by a Western blot with phospho‐specific antibodies. Results: Curcumin bound iron, but did not block iron uptake or bioavailability in T51B cells given FAC. However, it reduced cytotoxicity, blocked the generation of ROS and eliminated signalling to cellular stress pathways caused by iron. Inhibition was observed over a wide range of FAC concentrations (50–500 μM), with an apparent IC₅₀ in all cases between 5 and 10 μM curcumin. In contrast, desferoxamine blocked both iron uptake and toxic effects of iron at concentrations that depended on the FAC concentration. The effects of curcumin also differed from those of α‐tocopherol, which did not bind iron and was less effective at blocking iron‐stimulated ROS generation. Conclusions: Curcumin reduced iron‐dependent oxidative stress and iron toxicity in T51B cells without blocking iron uptake.     

Hepatic manifestations of inflammatory bowel diseases

Inflammatory bowel diseases are associated with various hepatobiliary disorders, reported both in Crohn's disease and ulcerative colitis. They may occur at any moment in the natural course of the disease. The prevalence of liver dysfunction rises from 3% to 50% accordingly to definitions used in different studies. Fatty liver is considered as the most common hepatobiliary complication in inflammatory bowel diseases while primary sclerosing cholangitis is the most specific one. Less frequently, inflammatory bowel diseases‐associated hepatobiliary disorders include: autoimmune hepatitis/ primary sclerosing cholangitis overlap syndrome, IgG4‐associated cholangiopathy, primary biliary cholangitis, hepatic amyloidosis, granulomatous hepatitis, cholelithiasis, portal vein thrombosis and liver abscess. The spectrum of these manifestations varies according to the type of inflammatory bowel diseases. Treatments of inflammatory bowel diseases may cause liver toxicity, although incidence of serious complications remains low. However, early diagnosis of drug‐induced liver injury is of major importance as it affects future clinical management. When facing abnormal liver tests, clinicians should undertake a full diagnostic work‐up in order to determine whether the hepatic abnormalities are related to the inflammatory bowel diseases or not. Management of hepatic manifestations in inflammatory bowel diseases usually involves both hepatologists and gastroenterologists because of the complexity of some situations.     

Attenuation of N-nitrosodiethylamine-induced liver fibrosis by high-molecular-weight fucoidan derived from Cladosiphon okamuranus

Background and Aim: Liver fibrosis is closely associated with the progression of various chronic liver diseases. Fucoidan exhibits different biological properties such as anti‐inflammatory, anti‐oxidant and anti‐fibrotic activities. The aim of this study was to determine whether oral fucoidan administration inhibits N‐nitrosodiethylamine (DEN)‐induced liver fibrosis. Methods: Liver fibrosis was induced in rats by injecting DEN (50 mg/kg). Rats were given 2% of crude fucoidan solution or 2% of high‐molecular‐weight (HMW) fucoidan solution. They were divided into a crude fucoidan group, an HMW fucoidan group, a DEN alone group, a DEN + crude fucoidan group, a DEN + HMW fucoidan group and a control group. Results: Liver fibrosis and hepatic hydroxyproline levels were significantly more decreased in the DEN + HMW fucoidan group than in the DEN‐alone group. Anti‐fibrogenesis was unremarkable in the DEN + crude fucoidan group. Hepatic messenger RNA levels and immunohistochemistry of transforming growth factor beta 1 were markedly increased by DEN. This increase was attenuated by HMW fucoidan. Hepatic chemokine ligand 12 expression was increased by DEN. This increase was suppressed by HMW fucoidan. HMW fucoidan significantly decreased the DEN‐induced malondialdehyde levels. Also, fucoidan markedly increased metallothionein expression in the liver. Fucoidan was clearly observed in the liver by immunohistochemical staining in HMW fucoidan‐treated rats, while it was faintly stained in the livers of crude fucoidan‐treated rats. Conclusion: These findings suggest that the HMW fucoidan treatment causes anti‐fibrogenesis in DEN‐induced liver cirrhosis through the downregulation of transforming growth factor beta 1 and chemokine ligand 12 expressions, and that scavenging lipid peroxidation is well‐incorporated in the liver.     

Hepatoprotective effect of the selective mineralocorticoid receptor antagonist, eplerenone against carbon tetrachloride-induced liver injury in rats

Background. Eplerenone is a selective mineralocorticoid receptor (MR) antagonist, and its potential protective role in cardiovascular injury has been reported by several studies. However, whether and how this drug can ameliorate hepatic injury in rats is unknown.Material and methods. The present study was conducted to investigate effect of eplerenone against liver injury induced by carbon tetrachloride (CCl₄) in rats. The biochemical liver function tests and oxidative stress parameters including malondialdehyde (MDA), reactive oxygen species (ROS), in addition to the reduced glutathione (GSH) levels were evaluated. Moreover, serum tumor necrotic factors (TNF-α) level and histopathological changes were examined.Results. Our results show that pre-treatment with eplerenone (4 mg/kg per day for 4 weeks) revealed attenuation in serum activities of alanine aminotransferase (ALT), aspartate aminotransferase, (AST), alkaline phosphatase (ALP) and bilirubin levels that were enhanced by CCl₄. Further, pre-treatment with eplerenone inhibited the elevated hepatic MDA content and restored hepatic GSH to its normal level. The enhanced hepatic ROS production in CCl₄-treated group was markedly decreased by eplerenone administration. Eple-renone pre-treatment significantly attenuated the inflammatory responses caused by CCl₄ as evident by the decreased serum TNF-α level. Histopathological studies showed that eplerenone alleviated the liver damage and reduced the lesions caused by CCl₄.Conclusion. Collectively, the present study provides a proof to hepatoprotective actions of eplerenone via reducing oxidative stress and inflammatory responses in CCl₄-induced liver damage in rat model.     

Effects of 1‐O‐hexyl‐2,3,5‐trimethylhydroquinone on carbon tetrachloride‐induced hepatic cirrhosis in rats

Aim: The present study was undertaken to evaluate the effects of 1‐O‐hexyl‐2,3,5‐trimethylhydroquinone (HTHQ), a synthesized vitamin E derivative, on carbon tetrachloride (CCl₄)‐induced cirrhosis. Methods: Rats were treated with hypodermic injections of CCl₄ twice a week to induce the hepatic cirrhosis, and given drinking water containing HTHQ or solvent. Primary cultures of rat hepatocytes were performed to evaluate the effects of HTHQ on the expression of inducible nitric oxide synthase (iNOS). Results: Masson's staining of rat livers showed fibrosis around pseudo‐lobules in the CCl₄ group, the lesions being reduced in the CCl₄ HTHQ group. Increases in liver tissue hydroxyproline and α₁(I) collagen, α‐smooth muscle actin and iNOS induced by CCl₄, were also markedly diminished by HTHQ. Furthermore, both HTHQ and vitamin E attenuated interleukin‐1β‐induced iNOS protein expression in cultured hepatocytes, the potency of HTHQ being 10‐times higher than that of vitamin E. Conclusion: HTHQ may inhibit development of hepatic cirrhosis in rats, more potently than vitamin E, by inhibiting the iNOS expression in hepatocytes. Because vitamin E has a radical scavenging action, roles of NO and peroxynitrite will be discussed in the effects of HTHQ on the fibrosis.     

Altered factor VII activating protease expression in murine hepatic fibrosis and its influence on hepatic stellate cells

Background: Platelet‐derived growth factor‐BB (PDGF‐BB) is a profibrotic factor in liver fibrosis through its ability to stimulate hepatic stellate cells (HSC). The liver‐derived serine protease factor VII activating protease (FSAP) regulates the activities of PDGF‐BB in a cell‐specific manner. Aims: Our aim was to determine the influence of FSAP on the activation of HSC and to analyse the regulation of FSAP in hepatic fibrogenesis. Methods: The effect of FSAP on PDGF‐stimulated p42/p44 mitogen‐activated protein kinase (MAPK) activation in primary rat HSC was determined by Western blotting. Migration and proliferation of HSC was evaluated in Boyden chamber experiments and ³H‐thymidine incorporation assays respectively. Expression of FSAP was analysed in a CCl₄ mouse model of liver fibrosis by Western blot, quantitative real‐time polymerase chain reaction and immunohistochemistry. Results: FSAP inhibited PDGF‐BB‐stimulated p42/p44 MAPK phosphorylation, proliferation and migration of HSC. FSAP mRNA expression level was increased 3 h after CCl₄ application and decreased after 18 h and, in established fibrosis, after chronic CCl₄ administration. In parallel, there was a decrease in the circulating FSAP protein in chronic fibrosis. Concurrently, the homogenous hepatic expression pattern of FSAP was disturbed. Immunohistochemistry revealed a decrease of FSAP in hepatocytes in inflammatory and fibrotic lesions. Conclusions: Our results demonstrate an inhibitory effect of FSAP on PDGF‐mediated activation of HSC. In addition, FSAP expression is transiently increased in acute‐phase reaction but decreased during chronic fibrogenesis, which in turn may influence PDGF‐BB availability and myofibroblast activity.     

All‐trans‐retinoic acid ameliorates carbon tetrachloride‐induced liver fibrosis in mice through modulating cytokine production

Background/Aims: Liver fibrosis with any aetiology, induced by the transdifferentiation and proliferation of hepatic stellate cells (HSCs) to produce collagen, is characterized by progressive worsening in liver function, leading to a high incidence of death. We have recently reported that all‐trans‐retinoic acid (ATRA) suppresses the transdifferentiation and proliferation of lung fibroblasts and prevents radiation‐ or bleomycin‐induced lung fibrosis. Methods: We examined the impact of ATRA on carbon tetrachloride (CCl₄)‐induced liver fibrosis. We performed histological examinations and quantitative measurements of transforming growth factor (TGF)‐β1 and interleukin (IL)‐6 in CCl₄‐treated mouse liver tissues with or without the administration of ATRA, and investigated the effect of ATRA on the production of the cytokines in quiescent and activated HSCs. Results: CCl₄‐induced liver fibrosis was attenuated in histology by intraperitoneal administration of ATRA, and the overall survival rate at 12 weeks was 26.5% without ATRA (n=25), whereas it was 75.0% (n=24) in the treatment group (P=0.0187). In vitro studies disclosed that the administration of ATRA reduced (i) the production of TGF‐β1, IL‐6 and collagen from HSCs, (ii) TGF‐β‐dependent transdifferentiation of the cells and IL‐6‐dependent cell proliferation and (iii) the activities of nuclear factor‐κB p65 and p38mitogen‐activated protein kinase, which stimulate the production of TGF‐β1 and IL‐6, which could be the mechanism underlying the preventive effect of ATRA on liver fibrosis. Conclusions: Our findings indicate that ATRA ameliorates liver fibrosis. As the oral administration of the drug results in good compliance, ATRA could be a novel approach in the treatment of liver fibrosis.     

Attenuated liver fibrosis after bile duct ligation and defective hepatic stellate cell activation in neural cell adhesion molecule knockout mice

Aim: Neural cell adhesion molecule (N‐CAM) is expressed by activated hepatic stellate cells (HSC), portal fibroblasts, cholangiocytes and hepatic progenitor cells during liver injury. Its functional role in liver disease and fibrogenesis is unknown. The aim of this study was to investigate the role of N‐CAM in liver fibrogenesis. Methods: To induce fibrosis, N‐CAM knockout mice and wild‐type controls were subjected to bile duct ligation (BDL) or repeated carbon tetrachloride (CCl₄) injections. Fibrosis was quantified by hydroxyproline, immunhistochemistry staining and image analysis. Protein levels were determined with immunoblotting. HSCs were isolated by ultracentrifugation in a Larcoll gradient and thereafter in vitro stimulated with recombinant transforming growth factor (TGF)‐β1. Results: Two weeks after BDL, wild‐type mice had developed pronounced liver fibrosis while N‐CAM?/? mice had less such alterations. N‐CAM?/? mice had less deposition of collagen and fibronectin seen in immunhistochemistry. The protein levels of fibronectin were higher in the liver from the wild type, while laminin were unaltered. CCl₄‐treated N‐CAM?/? and wild‐type mice showed no significant difference in the extent of liver fibrosis or the expression levels of the above‐mentioned genes. HSC isolated from N‐CAM?/? mice showed declined levels of smooth muscle actin and desmin after stimulation in vitro with TGF‐β1. Conclusions: Loss of N‐CAM results in decreased hepatic collagen and fibronectin deposition in mice subjected to BDL, but not in animals exposed to repeated CCl₄ injections. HSC isolated from N‐CAM null mice show impaired activation in vitro. This indicates a role of N‐CAM in cholestatic liver disease and HSC activation.     

Curcumin ameliorates acute thioacetamide-induced hepatotoxicity

BACKGROUND AND AIM: Increased production of reactive oxygen species and nitric oxide and activation of nuclear factor kappa B are implicated in the pathogenesis of various liver diseases, including fulminant hepatic failure. Curcumin is a naturally occurring anti-oxidant that reduces oxidative stress and inhibits nuclear factor kappa B and nitric oxide formation. The aim of the present study is to assess curcumin's therapeutic potential in acute thioacetamide hepatotoxicity, a rat model of fulminant hepatic failure. METHODS: Fulminant hepatic failure was induced by two intraperitoneal (i.p.) injections of 300 mg/kg thioacetamide (TAA) at 24-h intervals. The experimental groups received a low-dose (200 mg/kg per day, i.p.) or a high-dose (400 mg/kg per day) of curcumin, initiated 48 h prior to the first TAA injection. A fourth group was administered neither TAA nor curcumin and served as a control. RESULTS: The survival rate was higher in both curcumin-treated groups compared to the TAA only treated group. Biochemical parameters of liver injury, blood ammonia and hepatic necroinflammation were lower in the low-dose curcumin group compared to TAA controls, and were further reduced in the high-dose group (P < 0.05 and P < 0.01, respectively). Curcumin treatment also reduced the TAA-induced elevated hepatic levels of thiobarbituric acid-reactive substances (TBARS), and inhibited the nuclear binding of nuclear factor kappa B (NFkappaB) and inducible nitric oxide (iNOS) protein expression. CONCLUSIONS: Curcumin improved survival and minimized oxidative stress, hepatocellular injury and hepatic necroinflammation, NFkappaB binding and iNOS expression in a rat model of FHF. These findings support the role of ROS, NFkappaB and iNOS in mediating liver insult due to TAA, and that of curcumin as a hepato-protectant.