miRNA-338-3p/CAMK IIα signaling pathway prevents acetaminophen-induced acute liver inflammation in vivo

INTRODUCTION AND OBJECTIVES

N-acetyl-p-aminophenol (APAP)-induced liver injury is a major clinical challenge worldwide. The present study investigated the molecular role of microRNA (miR)-338-3p in the development of APAP-induced acute liver injury.

MATERIALS AND METHODS

B6 mice were treated with an miR-338-3p agomir, antagomir, and intraperitoneally injected with APAP 24h later to induce acute liver injury. Histological analysis was performed to evaluate the degree of liver injury. The gene expression of miR-338-3p and its downstream regulators was measured by reverse transcription-quantitative PCR and western blot. The miR target was validated using a luciferase reporter assay.

RESULTS

The results revealed that miR-338-3p was significantly upregulated following the intraperitoneal administration of APAP. Augmenting miR-338-3p alleviated acute liver injury caused by APAP overdose, while silencing of miR-338-3p exhibited a detrimental effect. Moreover, miR-338-3p inhibited the expression of pro-inflammatory cytokines by preventing the aberrant activation of inflammatory signaling pathways, including the nuclear factor kappa-B (NF-κB)/mitogen-activated protein kinase (MAPK) signaling pathway. Furthermore, calcium/calmodulin-dependent protein kinase IIα (CAMK IIα) was identified as a direct target of miR-338-3p.

CONCLUSION

The present study demonstrated that miR-338-3p inhibited inflammation in APAP-induced acute liver injury.

Physalis peruviana L. Pulp Prevents Liver Inflammation and Insulin Resistance in Skeletal Muscles of Diet-Induced Obese Mice

A chronic high-fat diet (HFD) produces obesity, leading to pathological consequences in the liver and skeletal muscle. The fat in the liver leads to accumulation of a large number of intrahepatic lipid droplets (LD), which are susceptible to oxidation. Obesity also affects skeletal muscle, increasing LD and producing insulin signaling impairment. Physalis peruviana L. (PP) (Solanaceae) is rich in peruvioses and has high antioxidant activity. We assessed the ability of PP to enhance insulin-dependent glucose uptake in skeletal muscle and the capacity to prevent both inflammation and lipoperoxidation in the liver of diet-induced obese mice. Male C57BL/6J mice were divided into groups and fed for eight weeks: control diet (C; 10% fat, 20% protein, 70% carbohydrates); C + PP (300 mg/kg/day); HFD (60% fat, 20% protein, 20% carbohydrates); and HFD + PP. Results suggest that PP reduces the intracellular lipoperoxidation level and the size of LD in both isolated hepatocytes and skeletal muscle fibers. PP also promotes insulin-dependent skeletal muscle glucose uptake. In conclusion, daily consumption of 300 mg/kg of fresh pulp of PP could be a novel strategy to prevent the hepatic lipoperoxidation and insulin resistance induced by obesity.

Pathobiology and diagnosis of clostridial hepatitis in animals

Clostridia can cause hepatic damage in domestic livestock, and wild and laboratory animals. Clostridium novyi type B causes infectious necrotic hepatitis (INH) in sheep and less frequently in other species. Spores of C. novyi type B can be present in soil; after ingestion, they reach the liver via portal circulation where they persist in phagocytic cells. Following liver damage, frequently caused by migrating parasites, local anaerobic conditions allow germination of the clostridial spores and production of toxins. C. novyi type B alpha toxin causes necrotizing hepatitis and extensive edema, congestion, and hemorrhage in multiple organs. Clostridium haemolyticum causes bacillary hemoglobinuria (BH) in cattle, sheep, and rarely, horses. Beta toxin is the main virulence factor of C. haemolyticum, causing hepatic necrosis and hemolysis. Clostridium piliforme, the causal agent of Tyzzer disease (TD), is the only gram-negative and obligate intracellular pathogenic clostridia. TD occurs in multiple species, but it is more frequent in foals, lagomorphs, and laboratory animals. The mode of transmission is fecal-oral, with ingestion of spores from a fecal-contaminated environment. In affected animals, C. piliforme proliferates in the intestinal mucosa, resulting in necrosis, and then disseminates to the liver and other organs. Virulence factors for this microorganism have not been identified, to date. Given the peracute or acute nature of clostridial hepatitis in animals, treatment is rarely effective. However, INH and BH can be prevented, and should be controlled by vaccination and control of liver flukes. To date, no vaccine is available to prevent TD.

[The ultrastructural organization of the liver of rats with experimental hepatitis after drinking mineral water containing humic acids]

We undertook the ultrastructural analysis of liver parenchyma taken from male rats with experimental hepatitis induced by the administration of paracetamol at a dose of 1000 mg per 1 kg body weight either following a course of drinking mineral water containing humic acids at a concentration of 20 mg/sq. decimeter) or 14 days after the termination of the drug action (the after-effect phase). It was shown that the consumption of mineral water during 21 days resulted in the modification of the ultrastructural organization of hepatocytes apparent as the increased amount of cisterns in the granulosa endoplasmic system, glycogen rosettes, and mitochondrial polymorphism. These changes give evidence of the restoration of the energy, glycogen and protein synthesizing functions disturbed by paracetamol administration. The after-effect phase was characterized by the further strengthening of reparative processes and the functional activity of hepatic cells.

micro-Opioid receptor activation prevents acute hepatic inflammation and cell death

BACKGROUND AND AIMS

The detrimental impact of opioid agonist on the clinical management of inflammatory diseases remains elusive. Given the anti-inflammatory properties of the mu-opioid receptor (MOR) agonists at the intestinal barrier, we hypothesised that MOR activation might also dampen acute hepatic inflammation and cell death-major determinants in the pathogenesis of liver diseases.

PATIENTS AND METHODS

The expression of MOR in liver biopsy specimens and peripheral blood mononuclear cells of untreated patients with chronic hepatitis C virus infection and controls, primary hepatocytes and cell lines was determined by quantitative PCR, immunoblotting and/or immunohistochemistry. The effects of peripheral MOR agonist (d-Ala2,NMe-Phe4,Gly5-ol (DAMGO)) and/or antagonist (naloxone methiodide) were explored in two models of acute hepatitis in mice. MOR-deficient mice were used to evaluate the essential regulatory role of MOR during carbon tetrachloride (CCl(4))-induced hepatitis. The role of DAMGO in cell death was investigated using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) analysis and quantification of lactate dehydrogenase release.

RESULTS

The key role of MOR in the prevention of acute hepatic inflammation and cell death in vivo and in vitro is reported. Whereas MOR gene expression increased transiently in the model of acute liver injury and TNFalpha-treated HepG2 cells, an impaired expression of MOR mRNA in human chronic hepatitis C samples was found. Furthermore, preventive administration of the selective MOR agonist DAMGO enhanced hepatoprotective-signalling pathways in vivo that were blocked by using naloxone methiodide. Consistently, genetic and pharmacological inhibition of MOR enhanced the severity associated with experimental hepatotoxin-induced hepatitis. Finally, treatment with DAMGO was shown to prevent cell death in vitro in HepG2 cells in a MOR-dependent manner and to prevent concanavalin A- and CCl(4)-induced cell death in vivo, providing a possible explanation for the anti-inflammatory role of MOR activation in the liver.

CONCLUSIONS

The results indicate that MOR agonists may prevent acute hepatitis and hold promising therapeutic use to maintain remission in both chronic inflammatory bowel and liver diseases.

Peroxisome proliferator-activated receptor alpha protects against obesity-induced hepatic inflammation

Recently it has become evident that obesity is associated with low-grade chronic inflammation. The transcription factor peroxisome proliferator-activated receptor alpha (PPARalpha) has been shown to have a strong antiinflammatory action in liver. However, the role of PPARalpha in obesity-induced inflammation is much less clear. Therefore, the aim of our study was to determine whether PPARalpha plays a role in obesity-induced hepatic inflammation. To induce obesity, wild-type sv129 and PPARalpha(-/-) mice were exposed to a chronic high-fat diet (HFD), using a low-fat diet (LFD) as control. In wild-type mice, HFD significantly increased the hepatic and adipose expression of numerous genes involved in inflammation. Importantly, this effect was amplified in PPARalpha(-/-) mice, suggesting an antiinflammatory role of PPARalpha in liver and adipose tissue. Further analysis identified specific chemokines and macrophage markers, including monocyte chemotactic protein 1 and F4/80(+), that were elevated in liver and adipose tissue of PPARalpha(-/-) mice, indicating increased inflammatory cell recruitment in the knockout animals. When all groups of mice were analyzed together, a significant correlation between hepatic triglycerides and expression of inflammatory markers was observed. Many inflammatory genes that were up-regulated in PPARalpha(-/-) livers by HFD were down-regulated by treatment with the PPARalpha ligand Wy-14643 under normal nonsteatotic conditions, either in vivo or in vitro, suggesting an antiinflammatory effect of PPARalpha that is independent of reduction in liver triglycerides. In conclusion, our results suggest that PPARalpha protects against obesity-induced chronic inflammation in liver by reducing hepatic steatosis, by direct down-regulation of inflammatory genes, and by attenuating inflammation in adipose tissue.

[Gene expressions of LTC4 synthase homologs in Con A-induced mouse hepatitis and regulative effect of cyclosporine A]

OBJECTIVE

To explore the gene expressions of LTC4 synthase homologs in concanavalin A (Con A)-induced mouse hepatitis and regulation role of cyclosporine A (Cs A) treatment.

METHODS

Male Balb/c mouse liver injury model was developed by iv injection of Con A (20 mg/kg) and protected by Cs A pretreatment (150 mg/kg) before Con A administration. Blood samples were collected at indicated times after Con A treatment with or without Cs A pretreatment. Liver damage was assessed by serum transaminase ALT and AST measurement and histological evaluation. Meantime, three LTC4 synthase homolog gene expressions were determined by RT-PCR.

RESULTS

Serum ALT and AST upregulation were accompanied with histological damage at 2 h after Con A administration, and further aggravated at 8 h. mGST2 gene expression increased 1.7 fold at 2 h and 1.9 fold at 8 h, while the expression of LTC4 S and mGST3 changed little. Pretreatment with Cs A prevented mouse liver from injury by Con A and partly inhibited the mGST2 gene expression upregulation.

CONCLUSIONS

Administration of Con A in mouse lead to a significant increase of mGST2 gene expression without any significant effect on LTC4 S and mGST3 mRNA levels. Cs A pretreatment results in protection of liver damage, whereas fails to fully inhibit the increase of mGST2 gene expression.

Antinecrotic and antiapoptotic effects of hepatocyte growth factor on cholestatic hepatitis in a mouse model of bile-obstructive diseases

Cholestasis, an impairment of bile outflux, frequently occurs in liver diseases. In this process, an overaccumulation of bile acids causes hepatocyte necrosis and apoptosis, leading to advanced hepatitis. Hepatocyte growth factor (HGF) is mitogenic toward hepatocytes, but it is still unclear whether HGF has physiological and therapeutic functions during the progression of cholestasis. Using anti-HGF IgG or recombinant HGF in mice that had undergone bile duct ligation (BDL), we investigated the involvement of HGF in cholestasis-induced hepatitis. After the BDL surgery, HGF and c-Met mRNA levels transiently increased in livers during the progression of cholestatic hepatitis. When c-Met tyrosine phosphorylation was blocked in the livers of BDL-treated mice by anti-HGF IgG, hepatic dysfunction became evident, associated with the acceleration of hepatocyte necrosis and apoptosis. Inversely, administration of recombinant HGF into the mice led to the prevention of cholestasis-induced inflammation: HGF suppressed the hepatic expression of intracellular adhesion molecule-1 and neutrophil infiltration in BDL-treated mice. As a result, parenchymal necrosis was suppressed in the HGF-injected BDL mice. In addition, HGF supplement therapy reduced the number of apoptotic hepatocytes in cholestatic mice, associated with the early induction of Bcl-xL. The administration of HGF enhanced hepatic repair, via accelerating G1/S progression in hepatocytes. Our study showed that 1) upregulation of HGF production is required for protective mechanisms against cholestatic hepatitis and 2) enhancement of the intrinsic defense system by adding HGF may be a reasonable strategy to attenuate hepatic inflammation, necrosis, and apoptosis under bile-congestive conditions.

Anti-hepatitis B activities of ganoderic acid from Ganoderma lucidum

Ganoderic acid, from Ganoderma lucidum, at 8 microg/ml inhibited replication of hepatitis B virus (HBV) in HepG2215 cells over 8 days. Production of HBV surface antigen and HBV e antigen were 20 and 44% of controls without ganoderic acid. Male KM mice were significantly protected from liver injury, induced with carbon tetrachloride, by treatment with ganoderic acid at 10 mg and 30 mg/kg x d (by intravenous injection) 7 days. Ganoderic acid at the same dosage also significantly protected the mice from liver injury induced by M. bovis BCG plus lipopolysaccharide (from Escherichia coli 0127:B8).

Cholestasis induced by model organic anions protects from acetaminophen hepatotoxicity in male CD-1 mice

Administration of the non-metabolizable organic anion indocyanine green (ICG) prior to a toxic dose of acetaminophen (4-acetamidophenol; APAP) reduces liver injury 24h after dosing. ICG also produces a dose-dependent decrease in bile flow in mice and rats. Studies in bile duct-cannulated rats suggest that cholestasis can play a role in this protection. This study was conducted to determine if the ability of model organic anions to produce cholestasis is relevant to the protection against APAP hepatotoxicity afforded by ICG. In these studies, overnight fasted male CD-1 mice were dosed (i.v.) with the cholestatic dyes bromcresol green (BCG, 30 micromol/kg) and rose bengal (RB, 60 micromol/kg) immediately prior APAP administration (500 mg/kg, i.p.). Other groups of mice received the non-cholestatic dyes dibromosulphthalein (DBSP, 150 micromol/kg) and amaranth (AM, 300 micromol/kg) prior to APAP. Controls were given vehicle only. Hepatocellular necrosis was evident at 24 h in control mice receiving APAP. Pretreatment with the cholestatic dyes BCG and RB decreased the severity of hepatocellular necrosis induced by APAP. However, administration of the non-cholestatic dyes DBSP and AM did not alter APAP-induced liver damage. Glutathione replenishment was not altered by pretreatment with any of these dyes. Furthermore, ICG protected mice against carbon tetrachloride (CCl4) hepatotoxicity. Since CCl4 undergoes minimal biliary excretion and does not compete for biliary transport function, this finding supports the notion that cholestasis itself rather than competition for canalicular transporters is central to the hepatoprotection by ICG and other cholephilic dyes.

Melatonin-selenium nanoparticles inhibit oxidative stress and protect against hepatic injury induced by Bacillus Calmette-Guérin/lipopolysaccharide in mice

Melatonin-selenium nanoparticles (MT-Se), a novel complex, were synthesized by preparing selenium nanoparticles in melatonin medium. The present investigation was designed to determine the protective effects of MT-Se against Bacillus Calmette-Guérin (BCG)/lipopolysaccharide (LPS)-induced hepatic injury in mice. In BCG/LPS-induced hepatic injury model, MT-Se administered (i.g.) at doses of 5, 10, or 20 mg/kg to BCG/LPS-treated mice for 10 days, significantly reduced the increase in plasma aminotransferase, reduced the severe extent of hepatic cell damage and the immigration of inflammatory cells. The MT-Se particles also attenuated the increase in the content of thiobarbituric acid-reactive substances and enhanced the decrease in reduced activities of superoxide dismutase and glutathione peroxidase (GPx). However, treatment with MT-Se suppressed the increase in nitric oxide levels both in plasma and liver tissue. Furthermore, supplementation with MT-Se at the dose of 10 mg/kg (composed of 9.9 mg/kg melatonin and 0.1 mg/kg selenium) had great capability to protect against hepatocellular damage than a similar dose of melatonin (10 mg/kg) or selenium (0.1 mg/kg) alone. This effect may relate to its higher antioxidant efficacy in decreasing lipid peroxidation and increasing GPx activity. These results suggest that the mode of MT-Se hepatic protective action is, at least in part, related to its antioxidant properties.

Preventive effects of soyasapogenol B derivatives on liver injury in a concanavalin A-induced hepatitis model

To shed light on the structure-activity relationship, various soyasapogenol B derivatives were synthesized and evaluated for preventive effects on liver injury in the concanavalin A (Con A)-induced hepatitis model in mice. Con A injection into mice induces some pathophysiology of human liver disease such as autoimmune or viral hepatitis. Two hydroxyl groups on the A ring of soyasapogenol B are required for amelioration of liver damage. Modification of the C-22 hydroxyl moiety with an acyloxy or alkyloxy group, or removal of the hydroxyl group, resulted in a greatly enhanced percentage of alleviation. Among the series of soyasapogenol B derivatives examined, six compounds exhibited preventive effects on liver damage.

Efficacy of zinc supplementation in preventing acute hepatitis in Long-Evans Cinnamon rats

OBJECTIVES

Long-Evans Cinnamon (LEC) rats are characterized by an abnormal hepatic deposition of copper (Cu) due to a lack of the Cu-transporter P-type adenosine triphosphatase: accordingly, the strain is a good animal model of Wilson's disease. The effect of oral zinc (Zn) acetate treatment on the development of acute hepatitis and the biochemical parameters of Cu-induced liver damage was studied in 5-week-old LEC rats (n=52).

METHODS

Rats receiving 50 or 80 mg/ml/day Zn acetate by gavage and control rats receiving a daily dose of glucose solution 0.02 g/ml by gastric intubation were killed at 1, 2 or 8 weeks after the start of treatment.

RESULTS

Treatment with Zn acetate resulted in the prevention of acute hepatitis: 10 of the 13 untreated rats developed signs and symptoms compatible with acute hepatitis between the 6th and 7th week of treatment. Tissue metallothionein (MT) significantly increased in the treated rats and positively correlated with Zn concentrations within the liver. Control rats had a significantly higher iron concentration in the liver and kidneys compared with supplemented rats, after both short- and long-term experiments. 8-hydroxy-2'-deoxyguanosine amounts were significantly lower in untreated rats.

CONCLUSIONS

Zn acetate prevents acute hepatitis, by increasing tissue MT concentrations, reducing Cu absorption and interfering with Fe metabolism.

Mechanism of protective action of bicyclol against CCl-induced liver injury in mice

Bicyclol is a novel synthetic drug for the treatment of chronic viral hepatitis in China. This paper reports the protective action of bicyclol against experimental liver injury in mice and its mechanism of action. Oral administration of bicyclol markedly reduced the elevated serum transaminases (alanine aminotransferase (ALT) and aspartate aminotransferase (AST)) and the hepatic morphologic changes induced by CCl(4) in mice. Mechanistic studies demonstrated that bicyclol significantly inhibited CCl(4)-induced lipid peroxidation of liver microsomes and (14)CCl(4) covalent binding to microsomal lipids and proteins in vitro, and decreased the level of the trichloromethyl free radical (*CCl(3)) generated from CCl(4) metabolism by NADPH-reduced liver microsomes. On the other hand, bicyclol neither directly inhibited the activity of ALT or AST in vitro nor affected hepatic ALT protein content in mice. These results suggest that bicyclol has remarkable hepatoprotective effects and its mechanism of action may be related to a decrease in free radical-induced damage to hepatocytes.

Inhibitory effects of vitamin A on TCDD-induced cytochrome P-450 1A1 enzyme activity and expression

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an extremely potent environmental contaminant that produces a wide range of adverse biological effects, including the induction of cytochrome P450 1A1(CYP1A1) that may enhance the toxic effects of TCDD. Several studies indicated that concurrent supplementation of vitamin A could reduce the toxicity, and potentially inhibit CYP1A1 activity (measured as ethoxyresorufin-O-deethylase [EROD] activity). In the present study, we investigated the in vivo effects of vitamin A on EROD activities and the expression of CYP1A1 in the liver of TCDD-treated mice. In Experiment I, the mice were given a single oral dose of 40 mug TCDD/kg body weight with or without the continuous administration of 2500 IU vitamin A/kg body weight/day, and were killed on day 1, 3, 7, 14, or 28. In Experiment II, the mice were given daily an oral dose of 0.1 mug TCDD/kg body weight with or without supplement of 2000 IU vitamin A/kg body weight, and were killed on day 14, 28, or 42. In both experiments, TCDD caused liver damage and increase in relative liver weights, augmented the EROD activities and CYP1A1 expression, and increased the aryl hydrocarbon receptor (AhR) mRNA expression, but did not alter the AhR nuclear translocator (ARNT) mRNA expression. CYP1A1 mRNA expression and AhR mRNA expression showed a similar time course. The liver damage in TCDD + vitamin A-treated mice was less severe than that in TCDD-treated mice. EROD activities, CYP1A1 expression, and AhR mRNA expression in vitamin A + TCDD-treated mice were lower than those in TCDD-treated mice, indicating that supplementation of vitamin A might attenuate the liver damage caused by TCDD.

Fumonisin B1 hepatotoxicity in mice is attenuated by depletion of Kupffer cells by gadolinium chloride

Fumonisin B1 (FB1) is a toxic and carcinogenic mycotoxin produced by Fusarium verticillioides found on corn worldwide. The biological effects of FB1 are attributed to sphingolipid metabolism disruption as a result of ceramide synthase inhibition. Tumor necrosis factor alpha (TNFalpha) is an important modulator of FB1 hepatotoxicity. Kupffer cells are major source of cytokine production in liver. In the present study we investigated the effects of Kupffer cell depletion by gadolinium on FB1 hepatotoxicity in female BALB/c mice. Mice were given saline or 50 mg/kg of gadolinium chloride once via the tail vein; 16 h later they were treated with subcutaneous injections of vehicle or 2.25 mg/kg/day FB1 in saline for three successive days. Gadolinium significantly attenuated FB1-induced increases in the activities of circulating alanine aminotransferase and aspartate aminotransferase and reduced the FB1-induced hepatocyte apoptosis and free sphinganine accumulation in liver. Both gadolinium and FB1 treatments individually increased the expression of selected cell signal factors; e.g., TNFalpha, TNF receptor 1, TNF-related apoptosis-inducing ligand, lymphotoxin beta, interferon gamma, and transforming growth factor beta1; gadolinium chloride did not alter FB1-induced expression of the above genes. Results indicated that Kupffer cells play a role in FB1 hepatotoxicity. Decreased FB1-induced sphinganine accumulation and increased protective TNFalpha signaling by gadolinium chloride may in part account for its ameliorating effect on FB1 liver damage.

Protective effect of baicalin on tert-butyl hydroperoxide-induced rat hepatotoxicity

Baicalin (BA) is a flavonoid compound purified from Scutellaria baicalensis Georgi that is used as a traditional Chinese herbal medicine. Baicalin was studied for the mechanism of its inhibitory effects on the tert-butyl hydroperoxide (t-BHP)-induced cytotoxicity and lipid peroxidation in rat liver system. Baicalin expressed an antioxidant property by its capacity for quenching the free radicals of 1,1-diphenyl-2-picrylhydrazyl (DPPH). Further investigations using the t-BHP-induced cytotoxicity in rat primary hepatocytes demonstrated that baicalin, at the concentrations of 2-220 microM, significantly decreased the leakages of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT), and the formation of malondialdehyde (MDA) induced by 30 min treatment of t-BHP(1.5 mM). Baicalin also attenuated the t-BHP-induced depletion of glutathione (GSH) and high level of DNA repaired synthesis. An in vivo study in rats showed that pretreatment with baicalin (i.p.) at concentrations of 0.5 and 5 mg/kg for 5 days before a single i.p. dose of t-BHP (0.1 mmol/kg) significantly lowered the serum levels of hepatic enzyme markers (ALT and AST) and reduced oxidative stress in the liver. Histopathological evaluation of the rat livers revealed that baicalin reduced the incidence of liver lesions induced by t-BHP including hepatocyte swelling, leukocyte infiltration, and necrosis. Based on the results described above, we speculate that baicalin may play a chemopreventive role via reducing oxidative stress in living systems.

IL-6 prevents T cell-mediated hepatitis via inhibition of NKT cells in CD4+ T cell- and STAT3-dependent manners

The hepatoprotective effect of IL-6 on various forms of liver injury including T cell-mediated hepatitis has been well documented, and it is believed that induction of antiapoptotic proteins is an important mechanism. In this study, we provide evidence suggesting an additional mechanism involved in the protective role of IL-6 in T cell-mediated hepatitis. In NKT cell-depleted mice, Con A-induced liver injury is diminished; this can be restored by the adoptive transfer of liver mononuclear cells or NKT cells from wild-type mice, but not from IL-6-treated mice. In vitro IL-6 treatment inhibits the ability of mononuclear cells to restore Con A-induced liver injury in NKT-depleted mice, whereas the same treatment does not inhibit purified NKT cells from restoring the injury. The addition of CD3(+) T cells or CD4(+) T cells can restore the inhibitory effect of IL-6 on purified NKT cells, whereas the addition of CD3(+) T cells from CD4-deficient mice fails to restore this inhibitory effect. The expression of IL-6R was detected in 52.6% of hepatic CD3(+) T cells and 32.7% of hepatic CD4(+) T cells, but only in 3.9% of hepatic NK and 1.5% of hepatic NKT cells. Finally, treatment with IL-6 induces STAT3 activation in hepatic lymphocytes and hepatic T cells, and blocking such activation abolishes the inhibitory effect of IL-6 on hepatic lymphocytes to restore liver injury. Taken together, these findings suggest that in addition to its antiapoptotic abilities, as previously well documented, IL-6/STAT3 inhibits NKT cells via targeting CD4(+) T cells and consequently prevents T cell-mediated hepatitis.

Critical roles of TRAIL in hepatic cell death and hepatic inflammation

The TNF-related apoptosis-inducing ligand (TRAIL) induces apoptosis of tumor cells but not most normal cells. Its role in hepatic cell death and hepatic diseases is not clear. In vitro studies suggest that murine hepatocytes are not sensitive to TRAIL-induced apoptosis, indicating that TRAIL may not mediate hepatic cell death. Using two experimental models of hepatitis, we found that hepatic cell death in vivo was dramatically reduced in TRAIL-deficient mice and mice treated with a blocking TRAIL receptor. Although both TRAIL and its death receptor 5 were constitutively expressed in the liver, TRAIL expression by immune cells alone was sufficient to restore the sensitivity of TRAIL-deficient mice to hepatitis. Thus, TRAIL plays a crucial role in hepatic cell death and hepatic inflammation.

Essential Role for Neutrophil Recruitment to the Liver in Concanavalin A-Induced Hepatitis

Leukocyte infiltration into the liver is paramount to the development of liver injury in hepatitis. Hepatitis occurring after the administration of Con A in mice is felt to be a T lymphocyte-mediated disease. In this study, we report that neutrophils are the key initiators of lymphocyte recruitment and liver injury caused by Con A. The objectives of this study were to investigate the involvement of neutrophils in Con A-induced hepatitis in vivo via intravital microscopy. After Con A administration, we observed a significant increase in leukocyte rolling flux, a decrease in rolling velocity, and an increase in leukocyte adhesion to the hepatic microvasculature. Fluorescence microscopy identified that within 4 h of Con A administration only a minority of the recruited leukocytes were T lymphocytes. Furthermore, immunohistochemistry showed a significant increase in neutrophils recruited to the liver post-Con A treatment in association with liver cell damage, as reflected by elevated serum alanine aminotransferase levels. Using flow cytometry, we observed that Con A could bind directly to neutrophils, which resulted in a shedding of L-selectin, an increase in beta(2)-integrin expression, and the production of reactive oxidants. Following neutrophil depletion, a significant inhibition of Con A-induced CD4+ T lymphocyte recruitment to the liver resulted and complete reduction in hepatic injury, as assessed by serum alanine aminotransferase levels. In summary, the present data support the concept that neutrophils play an important and previously unrecognized role in governing Con A-induced CD4+ T cell recruitment to the liver and the subsequent development of hepatitis.

A Novel Synthetic Cannabinoid Derivative Inhibits Inflammatory Liver Damage via Negative Cytokine Regulation

The therapeutic potential of cannabinoids has been described previously for several inflammatory diseases, but the molecular mechanisms underlying the anti-inflammatory properties of cannabinoids are not well understood. In this study, we investigated the mechanism of action of a novel synthetic cannabinoid, [(+)(6aS,10aS)-6,6-Dimethyl-3-(1,1-dimethylheptyl)-1-hydroxy-9-(1H-imidazol-2-ylsulfanylmethyl]-6a,7,10,10a-tetrahydro-6H-dibenzo[b,d]pyran (PRS-211,092) that has no psychotropic effects but exhibits immunomodulatory properties. Treatment with PRS-211,092 significantly decreased Concanavalin A-induced liver injury in mice that was accompanied by: 1) promotion of early gene expression of interleukin (IL)-6 and IL-10 that play a protective role in this model; 2) induction of early gene expression of the suppressors of cytokine signaling (SOCS-1 and 3), followed by 3) inhibition of several pro-inflammatory mediators, including IL-2, monocyte chemoattractant protein-1 (MCP-1), IL-1beta, interferon-gamma, and tumor necrosis factor alpha. Based on these results, we propose a mechanism by which PRS-211,092 stimulates the expression of IL-6, IL-10 and the SOCS proteins that, in turn, negatively regulates the expression of pro-inflammatory cytokines. Negative regulation by PRS-211,092 was further demonstrated in cultured T cells, where it inhibited IL-2 production and nuclear factor of activated T cells activity. These findings suggest that this cannabinoid derivative is an immunomodulator that could be developed as a potential drug for hepatitis as well as for other short- or long-term inflammatory diseases.

C-C chemokine ligand 2/monocyte chemoattractant protein-1 directly inhibits NKT cell IL-4 production and is hepatoprotective in T cell-mediated hepatitis in the mouse

T cell-mediated liver diseases are associated with elevated serum levels of C-C chemokine ligand 2 (CCL2)/monocyte chemoattractant protein-1 (MCP-1). However, the extent to which the actions of CCL2/MCP-1 contribute to the pathogenesis of T cell-mediated hepatitis remains incompletely understood. Con A-induced hepatitis is a liver-specific inflammation mediated by activated T cells and is driven by an up-regulation of the hepatic expression of TNF-alpha, IFN-gamma, and IL-4. The present study examined the role of CCL2/MCP-1 in the pathogenesis of T cell-mediated hepatitis induced by Con A administration in the mouse. We demonstrate a novel hepatoprotective role for CCL2/MCP-1 during Con A-induced hepatitis, because CCL2/MCP-1 neutralization strikingly enhanced hepatic injury, both biochemically and histologically, after Con A administration. Furthermore, CCL2/MCP-1 neutralization was associated with a significant reduction in the hepatic levels of TNF-alpha and IFN-gamma, but with a significant increase in hepatic IL-4 levels. Moreover, IL-4 production and CCR2 expression by Con A-stimulated CD3(+)NK1.1(+) T cells was significantly reduced by rMCP-1 treatment in vitro. In summary, we propose that CCL2/MCP-1 fulfills a novel anti-inflammatory role in T cell-mediated hepatitis by inhibiting CD3(+)NK1.1(+) T cell-derived IL-4 production through direct stimulation of its specific receptor CCR2. These findings may have direct clinical relevance to T cell-mediated hepatitis.

Constitutive expression of the adenovirus E3-14.7K protein does not prolong adenovirus vector DNA persistence but protects mice against lipopolysaccharide-induced acute hepatitis

First-generation adenovirus vectors, deleted in the E1 and E3 regions of the genome, induce a strong inflammatory response that affects persistence of vector DNA in transduced organs and causes toxicity in the host. Wild-type adenovirus encodes a number of proteins that are nonessential for viral propagation in vitro but that dampen the inflammatory and immune responses mounted by the host during infection. The adenovirus E3 region-encoded 14.7K protein inhibits tumor necrosis factor alpha (TNF-alpha)-induced apoptosis and arachidonic acid synthesis. To evaluate the impact of constitutive expression of the 14.7K protein on vector-induced pathology, toxicity, and DNA persistence, we constructed vectors that contain a cytomegalovirus promoter-driven 14.7K expression cassette. Although these vectors inhibit TNF-alpha-induced apoptosis in vitro, they do not show better vector DNA persistence, or lower inflammation or pathology than E3-deleted first-generation vector in mouse models. However, the 14.7K protein is functional in mice because animals injected intravenously with a 14.7K-constitutive vector were fully protected against a lethal dose of lipopolysaccharide 5 days after vector administration. These results open new applications for the E3-encoded 14.7K protein, which can be used to protect organs against inflammatory reactions and TNF-alpha-mediated apoptosis.

IL-18-binding protein protects against lipopolysaccharide- induced lethality and prevents the development of Fas/Fas ligand-mediated models of liver disease in mice

IL-18-binding protein (IL-18BP) is a natural IL-18 inhibitor. Human IL-18BP isoform a was produced as fusion construct with human IgG1 Fc and assessed for binding and neutralizing IL-18. IL-18BP-Fc binds human, mouse, and rat IL-18 with high affinity (K(D) 0.3-5 nM) in a BIAcore-based assay. In vitro, IL-18BP-Fc blocks IL-18 (100 ng/ml)-induced IFN-gamma production by KG1 cells (EC(50) = 0.3 microg/ml). In mice challenged with an LD(90) of LPS (15 mg/kg), IL-18BP-Fc (5 mg/kg) administered 10 min before LPS blocks IFN-gamma production and protects against lethality. IL-18BP-Fc administered 10 min before LPS blocks IFN-gamma production induced by LPS (5 mg/kg) with ED(50) of 0.005 mg/kg. Furthermore, IL-18BP-Fc (5 mg/kg) abrogates LPS (5 mg/kg)-induced IFN-gamma production even when administered 6 days before LPS but shows no effect when administered 9 or 12 days before LPS. Given 10 min before LPS challenge to mice primed 12 days in advance with heat-killed Propionibacterium acnes, IL-18BP-Fc prevents LPS-induced liver damage and IFN-gamma and Fas ligand expression. Given at the moment of priming with P. acnes, IL-18BP-Fc decreases P. acnes-induced granuloma formation, macrophage-inflammatory protein-1alpha and macrophage-inflammatory protein-2 production and prevents sensitization to LPS. IL-18BP-Fc also prevents Con A-induced liver damage and IFN-gamma and Fas ligand expression as well as liver damage induced by Pseudomonas aeruginosa exotoxin A or by anti-Fas agonistic Ab. In conclusion, IL-18BP can be engineered and produced in recombinant form to generate an IL-18 inhibitor, IL-18BP-Fc, endowed with remarkable in vitro and in vivo properties of binding and neutralizing IL-18.

Inhibition of matrix metalloproteinases blocks lethal hepatitis and apoptosis induced by tumor necrosis factor and allows safe antitumor therapy

Acute and fulminant liver failure induced by viral hepatitis, alcohol or other hepatotoxic drugs, are associated with tumor necrosis factor (TNF) production. In a mouse model of lethal hepatitis induced by TNF, apoptosis and necrosis of hepatocytes, but also lethality, hypothermia and influx of leukocytes into the liver, are prevented by a broad-spectrum matrix metalloproteinase (MMP) inhibitor, BB-94. Mice deficient in MMP-2, MMP-3 or MMP-9 had lower levels of apoptosis and necrosis of hepatocytes, and better survival. We found induction of MMP-9 activity and fibronectin degradation. Our findings suggest that several MMPs play a critical role in acute, fulminant hepatitis by degrading the extracellular matrix and allowing massive leukocyte influx in the liver. BB-94 also prevented lethality in TNF/interferon-gamma therapy in tumor-bearing mice. A broad-spectrum MMP inhibitor may be potentially useful for the treatment of patients with acute and perhaps chronic liver failure, and in cancer therapies using inflammatory cytokines.

Neutralization of interferon-gamma in neonatal SOCS1-/- mice prevents fatty degeneration of the liver but not subsequent fatal inflammatory disease

Mice lacking the suppressor of cytokine signalling-1 (SOCS1) die within weeks of birth with extensive fatty degeneration of the liver, consistent with acute hepatic toxicity to interferon-gamma (IFN-gamma), and inflammation of multiple organs. We show here that treatment for 1 week from birth with neutralizing antibody to IFN-gamma rescues SOCS1-/- mice from lethal liver disease but the mice subsequently succumb to chronic inflammatory lesions characterized by T-lymphocyte infiltration of skeletal muscle, pancreas, lung, liver and skin. Elevated blood levels of eosinophils, neutrophils and platelets were also observed and the thymic lymphocyte population was depleted of CD4+ CD8+ T cells and showed a reduced CD4 : CD8 ratio. All T-cell populations in thymus, spleen and lymph node exhibited an increased proportion of cells bearing the activation marker CD44. These data suggest an important role for SOCS1 in T-lymphocyte regulation.

Hypercholesterolemia exacerbates virus-induced immunopathologic liver disease via suppression of antiviral cytotoxic T cell responses

The immune system has to be optimally balanced to be highly effective against infections with cytopathic microbial pathogens and must guarantee efficient destruction of cells infected with noncytopathic agents while leaving the integrity of noninfected cells largely unaltered. We describe here the effects of genetically induced hypercholesterolemia on cellular immunity in apolipoprotein E (ApoE(-/-)) and low density lipoprotein receptor-deficient (LDLR(-/-)) mice during infection with the hepatotropic lymphocytic choriomeningitis virus WE strain. In both ApoE(-/-) and LDLR(-/-) mice hypercholesterolemia aggravated virus-induced immunopathologic liver disease. ApoE(-/-) mice exhibited a higher susceptibility to virus-induced immunopathology than LDLR(-/-) mice and usually succumbed to immunopathologic disease when infected with high doses of virus. Initial virus spread was not influenced by the hypercholesterolemia, whereas clearance of the virus from spleen and nonlymphoid organs, including liver, was delayed. Activation of antiviral CTL, measured by ex vivo cytotoxicity and IFN-gamma production, and recruitment of specific CTL into blood and liver were impaired in hypercholesterolemic mice, indicating that hypercholesterolemia had a significant suppressive effect on cellular immunity. Taken together, these data provide evidence that hypercholesterolemia suppresses antiviral immune responses, thereby changing the host-virus balance, and can increase susceptibility to acute or chronic and potentially lethal virus-induced immunopathologic disease. These findings impinge on our understanding of hypercholesterolemia as a disease parameter and may explain aspects of the frequent association of persistent pathogens with hypercholesterolemia-induced diseases, such as atherosclerosis.

In vivo evidence for accelerated generation of hydroxyl radicals in liver of Long-Evans Cinnamon (LEC) rats with acute hepatitis

The Long-Evans Cinnamon (LEC) rats accumulate excess copper (Cu) in the liver in a manner similar to patients with Wilson's disease (WD) and spontaneously develop acute hepatitis with severe jaundice. Although hydroxyl radicals (*OH) have been proposed to be a cause of hepatitis by the accumulation of Cu, it is not clear whether or not *OH can be produced in the liver of hepatitic LEC rats in vivo and also can be involved in the onset of hepatitis. In the present study, *OH production in plasma and liver of hepatitic LEC rats was quantified by trapping *OH with salicylic acid (SA) as 2, 3-dihydroxybenzoic acid (2, 3-DHBA). The ratios of 2, 3-DHBA/SA were significantly higher in plasma and liver of hepatitic LEC rats than those of Wistar rats and LEC rats showing no signs of hepatitis. Furthermore, the ratios of 2, 3-DHBA/SA in plasma and liver of hepatitic LEC rats were almost the same as those of Wistar rats treated orally with CuSO(4) (0.5 mmol/kg) 2 h before acetylsalicylic acid (ASA) injection. We also evaluated the protective effects of D-mannitol (a *OH scavenger) treatment against acute hepatitis in LEC rats. D-mannitol (500 mg/kg) was administered intraperitoneally to 10-week-old LEC rats for 3 weeks. D-mannitol treatment suppressed the increases in serum aspartate aminotransferase activity and total bilirubin concentration. In addition, D-mannitol treatment significantly reduced hepatic mitochondrial lipid peroxidation, which is thought to be important in the pathogenesis of Cu-induced hepatotoxicity. These observations suggest that accelerated generation of *OH catalyzed by free Cu in the liver may, at least in part, play a role in the pathogenesis of acute hepatitis in LEC rats.

Inhibition of anti-Fas antibody-induced mice hepatitis by furocoumarin derivatives

The effects of imperatorin and its synthetic derivative, Y355, on anti-Fas antibody-induced mice hepatitis were studied. Pretreatment of mice by intraperitoneal administration of imperatorine or Y355 at 30 mg/kg inhibited more than 80% of the anti-Fas antibody (150 microg/kg, i.v.)-induced elevation of plasma alanine aminotransferase activity. Furthermore, oral administration of imperatorin or Y355 at 100 mg/kg also had an inhibitory effect on anti-Fas antibody-induced hepatitis. Both compounds inhibited anti-Fas antibody (250 microg/kg)-induced caspase-1 and caspase-3 activities. The present results showed the inhibition of anti-Fas antibody-induced hepatitis by imperatorin and Y355, which might be a result of inhibition of caspase activities.

Inhibition of concanavalin A-induced mice hepatitis by coumarin derivatives

The effects of coumarin derivatives, osthole, imperatorin, Pd-Ia, Pd-II and Pd-III, on mice concanavalin A (Con A) (0.2 mg/mouse, i.v.)-induced hepatitis were studied. At the dose of 200 mg/kg (i.p.), these coumarins inhibited more than 90% of the Con A-induced elevation of plasma alanine aminotransferase activity, but glycyrrhizin (200 mg/kg, i.p.) caused only 45% inhibition. At the dose of 100 mg/kg (i.p.), osthole produced the strongest inhibition among these coumarins. The inhibitory activity of osthole is lost when its 7-methoxy group is replaced by a 7-hydroxy group to form osthenol. The present results showed that coumarin derivatives inhibited Con A-induced hepatitis, with osthole being the most inhibitory.

Reduction of liver Fas expression by an antisense oligonucleotide protects mice from fulminant hepatitis

Aberrant apoptosis-mediated cell death is believed to result in a number of different human diseases. For example, excessive apoptosis in the liver can result in fulminant and autoimmune forms of hepatitis. We have explored the possibility that inhibition of Fas expression in mice would reduce the severity of fulminant hepatitis. To do this, we have developed a chemically modified 2'-O-(2-methoxy)ethyl antisense oligonucleotide (ISIS 22023) inhibitor of mouse Fas expression. In tissue culture, this oligonucleotide induced a reduction in Fas mRNA expression that was both concentration- and sequence-specific. In Balb/c mice, dosing with ISIS 22023 reduced Fas mRNA and protein expressions in liver by 90%. The ID50 for this response was 8-10 mg kg-1 daily dosing, and the reduction was highly dependent on oligonucleotide sequence, oligonucleotide concentration in liver, and treatment time. Pretreatment with ISIS 22023 completely protected mice from fulminant hepatitis induced by agonistic Fas antibody, by a mechanism entirely consistent with an oligonucleotide antisense mechanism of action. In addition, oligonucleotide-mediated suppression of Fas expression reduced the severity of acetaminophen-mediated fulminant hepatitis, but was without effect on concanavalin A-mediated hepatitis. Our results demonstrate that 2'-O-(2-methoxy)ethyl containing antisense oligonucleotides targeting Fas can exert in vivo pharmacological activity in liver, and suggest that oligonucleotide inhibitors of Fas may be useful in the treatment of human liver disease.

Hepatoprotective effects of Inula britannica on hepatic injury in mice

Inula britannica, a Kampo medicine, is prepared from the heads of Compositae plants such as Inula britannica L., which has been used clinically as a remedy for nausea, hiccup and excessive sputum. Here it is shown that administration of Inula britannica improves the survival rate of mice with hepatic injury induced by LPS/PA. It is also suggested that administration of Inula britannica significantly reduces the fluctuation in the amount of cytokine in the spleen of mice with hepatic injuries, and that the Th1/Th2 control effect is related to the inhibitory action of Inula britannica against hepatic injury. In vitro testing suggests that Inula britannica suppresses Th1 differentiation and induces Th2 differentiation by inhibiting the production of macrophage IL-12 and promoting the production of IL-10, thus showing the immunological effect of hepatic injury inhibition by affecting the balance between Th1 and Th2.

A novel murine anti-human Fas mAb which mitigates lymphadenopathy without hepatotoxicity

Defects in Fas-mediated apoptosis are implicated in autoimmune diseases including rheumatoid arthritis (RA). Although induction of Fas-mediated apoptosis could have therapeutic effects on these diseases, it might cause deleterious effects in liver as Fas ligand or an agonistic anti-murine Fas antibody Jo2 causes severe hepatic injury in mice. We report here on the interesting characteristics of the newly obtained anti-Fas mAb, HFE7A, which cross-reacts with the Fas molecules of various species ranging from human to mouse and mitigates autoimmune symptoms without hepatotoxicity in mice. The administration of HFE7A to mice induced apoptosis in the thymocytes, although administration of HFE7A to mice or to marmosets did not induce any sign of hepatitis. The effect of HFE7A on liver is different from that of anti-murine Fas antibody Jo2, which causes acute and lethal hepatic injury to mice. Administration of HFE7A reduced lymphadenopathy and abnormal T cells in MRL-gld/gld mice. HFE7A induced apoptosis in synovial cells prepared from RA patients. Surprisingly, HFE7A protected mice from fulminant hepatitis induced by Jo2. Therefore, HFE7A is a potential therapeutic antibody not only for autoimmune diseases including RA but also for fulminant hepatitis.

Protective effects of soyasapogenol A on liver injury mediated by immune response in a concanavalin A-induced hepatitis model

The present study was carried out to analyze the effects of soyasapogenol A on the liver injury mediated by the immune response in concanavalin A-induced hepatitis in mice. Soyasapogenol A reduced the number of infiltrating inflammatory cells in the liver and significantly lowered the elevated level of plasma tumor necrosis factor-alpha (TNF-alpha) 2 h after concanavalin A treatment, and then markedly reduced the elevated plasma alanine aminotransferase activity and decreased the number of apoptotic bodies in the liver parenchymal cells but not in the sinusoidal cells at 24 h. Since the effect of soyasapogenol A on the elevated plasma TNF-alpha level was not appreciable compared to the preventive effect of soyasapogenol A on the elevated plasma alanine aminotransferase level, these results suggest that soyasapogenol A directly prevents apoptosis of hepatocytes, and secondly, inhibits the elevation of plasma TNF-alpha, which consequently resulted in the prevention of liver damage in the concanavalin A-induced hepatitis model.

Dissolution of copper-rich granules in hepatic lysosomes by D-penicillamine prevents the development of fulminant hepatitis in Long-Evans cinnamon rats

BACKGROUND/AIM

The Long-Evans cinnamon rat has a mutation homologous to the human Wilson disease gene, leading to gross copper accumulation and the development of hepatitis. D-penicillamine, a copper-chelating drug widely and efficiently used in treating Wilson disease, has also been shown to prevent hepatitis in Long-Evans cinnamon rats. The objectives of this study were: i) to investigate the effectiveness of D-penicillamine when administered to the already affected animals, and ii) to elucidate the mechanism of action of the drug.

METHODS

Long-Evans cinnamon rats were divided into groups according to age and treatment with D-penicillamine. The drug was administered orally before and after the onset of hepatitis. Livers were examined by light and electron microscopy. The effect of D-penicillamine on the subcellular distribution and binding of copper was investigated in more detail. Finally, the interaction between D-penicillamine and specific hepatic copper-binding proteins was studied in vitro.

RESULTS

D-penicillamine when given to either healthy or diseased animals prevented or reversed hepatitis, respectively. The drug particularly inhibited the disease-specific accumulation of copper in lysosomes of hepatocytes, tissue macrophages and Kupffer cells. When administered to diseased animals, the drug sequestered copper particularly from insoluble lysosomal particles. According to results obtained in vitro, the mobilization of this copper is likely to proceed through the solubilization of these particles. In contrast and as supported by the in vitro data, D-penicillamine had only a minor effect on copper bound to metallothionein in the cytosol.

CONCLUSION

Our findings on the Long-Evans cinnamon rat provide some conclusions on the mechanism of action of D-penicillamine in Wilson disease therapy. The drug prevents the formation or promotes the solubilization of copper-rich particles which occur in lysosomes of hepatocytes and Kupffer cells in the livers of patients with Wilson disease. Once chelated with D-penicillamine copper might then be excreted into urine. However, the mobilization of copper by D-penicillamine seems to be limited due to the binding of the metal to metallothionein in liver cytosol. This copper, even at relatively high concentrations, apparently may be well tolerated.

The protective effect of glycyrrhizin on anti-Fas antibody-induced hepatitis in mice

Fas ligand, which is a type II membrane protein, is a major inducer of apoptosis. The effect of glycyrrhizin on anti-Fas antibody-induced hepatitis in mice was studied. Pretreatment of mice with glycyrrhizin (100, 200 and 400 mg/kg, i.p.) inhibited the anti-Fas antibody (150 microg/kg, i.v.)-induced elevation of plasma aminotransferase activity in a dose-dependent manner. CPP32 is a cystein protease and CPP32-like activity induced by anti-Fas antibody injection was inhibited by glycyrrhizin (200 mg/kg). However, the addition of glycyrrhizin (up to 10(-4) M) to a liver cytosol fraction isolated from mice treated with anti-Fas antibodies (150 microg/kg, i.v.) did not inhibit the CPP32-like activity in vitro. The present results clearly show that glycyrrhizin inhibited anti-Fas antibody-induced hepatitis by acting upstream of CPP32-like protease activation.

Activation of caspases in lethal experimental hepatitis and prevention by acute phase proteins

Lethal hepatitis can be induced by an agonistic anti-Fas Ab in normal mice or by TNF in mice sensitized to d -(+)-galactosamine or actinomycin D. In all three models, we found that apoptosis of hepatocytes is an early and necessary step to cause lethality. In the three models, we observed activation of the major executioner caspases-3 and -7. Two acute-phase proteins, alpha1-acid glycoprotein and alpha1-antitrypsin, differentially prevent lethality: alpha1-acid glycoprotein protects in both TNF models and not in the anti-Fas model, while alpha1-antitrypsin confers protection in the TNF/d -(+)-galactosamine model only. The protection is inversely correlated with activation of caspase-3 and caspase-7. The data suggest that activation of caspase-3 and -7 is essential in the in vivo induction of apoptosis leading to lethal hepatitis and that acute phase proteins are powerful inhibitors of apoptosis and caspase activation. Furthermore, Bcl-2 transgenic mice, expressing Bcl-2 specifically in hepatocytes, are protected against a lethal challenge with anti-Fas or with TNF/d -(+)-galactosamine, but not against TNF/actinomycin D. The acute-phase proteins might constitute an inducible anti-apoptotic protective system, which in pathology or disturbed homeostasis prevents excessive apoptosis.

Glycyrrhizin protects mice from concanavalin A-induced hepatitis without affecting cytokine expression

The administration of concanavalin A (Con A) to mice induces cytokine-dependent hepatitis. In the present study, the effect of glycyrrhizin on Con A-induced hepatitis was examined. Treatment of mice with Con A (0.2 mg/mouse, i.v.) induced elevation of the plasma transaminase activities at 24 h. Mice were treated with glycyrrhizin (100, 200 and 400 mg/kg, i.p.), and glycyrrhizin at the doses of 200 and 400 mg/kg inhibited the Con A-induced elevation of the plasma transaminase activities. At 1 h after Con A treatment, interferon-gamma, tumor necrosis factor-alpha, interleukin-2 and interleukin-6 proteins were released into the plasma. Although treatment with glycyrrhizin at 200 mg/kg inhibited Con A-induced hepatitis, it did not affect the release of any of these Con A-induced cytokines into the plasma. The present results clearly show that glycyrrhizin inhibited Con A-induced hepatitis without affecting cytokine expression.

Active participation of CCR5(+)CD8(+) T lymphocytes in the pathogenesis of liver injury in graft-versus-host disease

We examined the molecular pathogenesis of graft-versus-host disease-associated (GVHD-associated) liver injury in mice, focusing on the role of chemokines. At the second week after cell transfer in the parent-into-F1 model of GVHD, CD8(+) T cells -- especially donor-derived CD8(+) T cells -- infiltrated the liver, causing both portal hepatitis and nonsuppurative destructive cholangitis (NSDC). These migrating cells expressed CCR5. Moreover, macrophage inflammatory protein-1alpha (MIP-1alpha), one of the ligands for CCR5, was selectively expressed on intralobular bile duct epithelial cells, endothelial cells, and infiltrating macrophages and lymphocytes. Administration of anti-CCR5 antibody dramatically reduced the infiltration of CCR5(+)CD8(+) T lymphocytes into the liver, and consequently protected against liver damage in GVHD. The levels of Fas ligand (FasL) mRNA expression in the liver were also decreased by anti-CCR5 antibody treatment. Anti-MIP-1alpha antibody treatment also reduced liver injury. These results suggest that MIP-1alpha-induced migration of CCR5-expressing CD8(+) T cells into the portal areas of the liver plays a significant role in causing liver injury in GVHD; thus, CCR5 and its ligand may be the novel target molecules of therapeutic intervention of hepatic GVHD.

Effects of various kinds of dietary amino acids on the hepatotoxic action of D-galactosamine in rats

The protective effects of various kinds of dietary amino acids against the hepatotoxic action of D-galactosamine (GalN) were examined. Male Wistar rats fed with 20% casein diets containing 10% or 5% amino acid for one week were injected with GalN (800 mg/kg body weight), and the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) activities, the hepatic glycogen concentration, and the serum glucose-level were examined 20 hours after the injection. In the groups with the 10% amino acid diets, activities of AST, ALT, and LDH in serum of 10% L-glutamine (Gln), 10% L-asparagine (Asn), and 10% L-serine (Ser) groups were significantly lower than those of the control group, and in the groups with the 5% amino acid diets, those activities of 5% L-histidine (His), 5% L-tyrosine (Tyr), 5% L-lysine (Lys), and 5% L-glycine (Gly) groups were also lower than those of the control group. The concentration of liver glycogen of 10% Gln-, 10% Asn-, and 10% Ser- groups and those levels of 5% His-, 5% Tyr-, 5% Lys-, and 5% Gly-groups were also significantly higher than that of the control group. As a result, it was found that some kinds of dietary amino acid such as L-Ser, L-Asn, L-His, L-Lys, L-Tyr, and L-Gly, in addition to L-Gln were effective to protect the rats from GalN-induced injury.

Preventive effect of zinc compounds, polaprezinc and zinc acetate against the onset of hepatitis in Long-Evans Cinnamon rat

It is known that Long-Evans Cinnamon (LEC) rats are characterized by the fulminant hepatitis occurring as a result of an abnormal hepatic deposition of Cu due to the lack of the Cu-transporter p-type ATPase. To prevent the hepatitis, two Zn compounds, Zn acetate and polaprezinc were given orally to LEC rats aged 30 days. At 100 days after birth, the control group composed of LEC rats fed a basal diet (Cu, 17 ppm; Zn, 50 ppm; Fe, 150 ppm) exhibited slight jaundice and showed high activities of serum enzymes related to hepatic function. The groups fed the diet fortified (1000 ppm as Zn) with Zn acetate or polaprezinc did not have jaundice. The hepatic Cu concentrations were 174 +/- 34 micrograms/g and 156 +/- 23 micrograms/g in the polaplezinc group and Zn acetate group, respectively. The control group showed 267 +/- 17 micrograms Cu/g and 298 +/- 62 micrograms Fe/g in the liver. The Fe concentration was about 1.7 times the concentration in the two Zn groups. Hepatic free Cu and Fe concentrations were 2.6 +/- 0.3 and 21.4 +/- 5.8 micrograms/g, 1.7 +/- 0.7 and 6.8 +/- 1.1 micrograms/g, and 1.3 +/- 0.1 and 6.2 +/- 0.8 micrograms/g in the control, polaprezinc and zinc acetate groups, respectively. Intestinal metallothionein (MT) concentrations were not increased significantly by the Zn diets. The two Zn compounds inhibit Cu absorption from the intestinal tract, resulting in a decrease of hepatic Cu deposition. The new Zn compound as well as Zn acetate is categorized as a therapeutic drug for Cu poisoning, including Wilson's disease.

[Comparative study of the effects of essentiale and the novel Russian hepatoprotective agent "phospholiv" in a model of acute hepatitis in rats]

Curative effect of new preparation "Phospholiv", elaborated in Institute of Biomedical Chemistry, in acute CCl4 induced rat hepatit model was studied. The preparation consists of polyunsaturated phosphatidylcholine and glycyrrhizinic acid salt. Recovery of damaged biosynthesis of albumin and total cell liver RNA--by incorporation of C14-leucine and C14-orotic acid--were observed after 3 days Phospholiv administration, that showed on reparation of damaged protein-synthesis system. Label incorporation into liver fraction > 80S--that was decreased under CCl4 influence--was also restored after Phospholiv treatment, that may testify on its regenerative effect on wholeness of subcellular hepatocytes structures. Substantial decrease of morphologic damages of liver tissue was demonstrated as well. Other phospholipid preparation--known hepatoprotector Essentiale--gave some positive effects too, but Phospholiv influence on biochemical and morphological liver features were 1.5-2 fold as compared with that of Essentiale. Results show on efficiency of polyunsaturated phospholipids in the treatment of acute hepatit in rats--as a result of influence on hepatocytes cell membrane--and on preferential effect of new hepatoprotector Phospholiv.

High-level constitutive expression of alpha 1-acid glycoprotein and lack of protection against tumor necrosis factor-induced lethal shock in transgenic mice

alpha 1-Acid glycoprotein (AGP) is an acute phase protein produced by hepatocytes. Although its exact biological function remains controversial, it was shown to protect galactosamine-sensitized or normal mice against hepatitis and lethal shock induced by tumor necrosis factor (TNF). Rat-AGP-transgenic mice, constitutively producing several mg AGP per ml serum were tested for their response to a combined challenge with TNF and D-(+)-galactosamine. A previously characterized, single transgenic line (9.5-5) was used. In contrast to our expectations both heterozygous or homozygous transgenic mice were not protected by the endogenously overproduced AGP. However, both transgenic and non-transgenic mice were protected by pretreatment with interleukin-1, an effect which we believe is mediated by the induction of acute phase proteins like AGP. Furthermore, both types of mice were protected by exogenous bovine AGP, suggesting that the lack of protection by endogenous AGP is not because of a repressed response to AGP. Finally, we demonstrate that purified AGP from the serum of transgenic mice is as protective as the AGP from non-transgenic mice or rats. The results suggest that AGP is protective only when its concentration is rapidly induced, perhaps because the endogenous steady state synthesis of AGP, in non-transgenic as well as transgenic mice, is coupled to the production of an AGP-binding factor. This study provides an interesting example of differences in outcome to a lethal challenge between an acute administered and a chronically produced protective protein.

[Use of a novel hepato-protective preparation "phospholiv" for inhibition of development of chronic hepatitis in rats]

Protective influence of a new phospholipid preparation "Phospholiv" was studied using a model of chronic hepatitis. Animals were treated 45 days intraperitoneay with CCl4 with parallel intragastral administration of Phospholiv or--(for comparison)--the of other phospholipid hepatoprotector, Essential. Morphologic changes of liver, as well as protein and RNA biosynthesis were evaluated in the end of experiment--by means of measuring C14-leucine and C14-orotic acid incorporation into hepatocyte subcellular fractions. Both phospholipid preparations attenuated dystrophic liver changes, Phospholiv effect being more pronounced. They both prevented CCl4 induced inhibition of label incorporation into subcellular fraction proteins, but only Phospholiv, promoted the maintaining normal level of radioactivity incorporation into cytosol proteins and hepatocyte RNA. The results, confirming certain protective effect of Essential, show more pronounced hepatoprotective action of the new preparation Phospholiv (developed on the basis of polyunsaturated phosphatidylcholine and glycyrrhizinic acid salt). Data show also on possible fit hepatitis treatment.

Pentoxifylline prevents concanavalin A-induced hepatitis by reducing tumor necrosis factor alpha levels and inhibiting adhesion of T lymphocytes to extracellular matrix

BACKGROUND/AIMS

Concanavalin A activates T lymphocytes and causes T cell-mediated hepatic injury in mice. Tumor necrosis factor alpha is a critical mediator in this experimental model. T-cell-mediated liver injury involves the migration of immune cells, notably CD4+ T lymphocytes, into liver tissue. Pentoxifylline is a strong suppressor of tumor necrosis factor alpha release and prevents leukocyte adherence to vascular endothelium and down-regulates the expression of intercellular adhesion molecule-1 in monocytes. In this study, we examined the efficacy of pentoxifylline as a potential therapeutic compound for the treatment of concanavalin A hepatitis.

METHODS

Balb/c mice were injected with 12 mg/kg concanavalin A with or without a single injection of pentoxifylline (5-300 mg/kg), 2 h prior to concanavalin A administration. Liver damage was evaluated by determining serum levels of liver enzymes and tumor necrosis factor alpha, and hepatic histopathology compared to mice treated with concanavalin A only. We also assessed the effects of pentoxifylline on the adhesive properties of T lymphocytes to fibronectin, as a paradigm for immune cell-extracellular matrix interactions required for migration. Pretreatment with pentoxifylline significantly reduced serum levels of liver enzymes (3800+/-650 vs 150+/-28 IU/l) and tumor necrosis factor alpha (710+/-105 vs 113+/-15 pg/ml) with no evidence of inflammation in histopathologic examination compared to control mice treated with concanavalin A. Pentoxifylline also inhibited the binding of murine T cells to fibronectin. All the effects of pentoxifylline were dose-dependent.

CONCLUSIONS

These results indicate that high doses of pentoxifylline can prevent concanavalin A hepatitis by suppression of tumor necrosis factor alpha release and inhibition of T cells adhesion to extracellular matrix.

Antibodies to tumor necrosis factor alfa attenuate hepatic necrosis and inflammation caused by chronic exposure to ethanol in the rat

Tumor necrosis factor (TNF)alpha, a pivotal cytokine involved in inflammation, is produced primarily by Kupffer cells in the liver. It has been shown that inactivation of Kupffer cells prevents alcohol-induced liver injury; therefore, the purpose of this study was to determine if neutralizing anti-TNF-alpha antibody is also effective. Male Wistar rats were exposed to ethanol (11 to 12 g x kg(-1) x d[-1]) continuously for up to 4 weeks via intragastric feeding using an enteral feeding model. Before ethanol exposure, polyclonal anti-mouse TNF-alpha rabbit serum was injected (2.0 mg/kg intravenously). There were no significant differences in body weight, mean ethanol concentration, or cyclic patterns of ethanol in urine when ethanol- and ethanol plus antibody-treated groups were compared. Expression of TNF-alpha and macrophage inflammatory protein 2 (MIP-2) messenger RNA (mRNA), determined using reverse transcription-polymerase chain reaction, was three- to four-fold higher in livers of ethanol-treated rats than in those of rats fed an ethanol-free, high-fat control diet. In addition, MIP-2 levels were also elevated when detected by Northern blot analysis. Anti-TNF-alpha antibody did not affect expression of mRNA for interleukin (IL) 1alpha, IL-6, transforming growth factor beta1, or TNF-alpha. However, MIP-2 mRNA expression, which is regulated by TNF-alpha, was decreased significantly by anti-TNF-alpha antibody treatment. Serum aspartate transaminase levels were elevated in ethanol-treated rats to 136 +/- 12 IU/L after 4 weeks but only reached 90 +/- 5 IU/L (P < .05) in rats treated with anti-TNF-alpha antibody. The hepatic inflammation and necrosis observed in ethanol-fed rats were attenuated significantly by antibody treatment, and steatosis was not. These results support the hypothesis that TNF-alpha plays an important role in inflammation and necrosis in alcohol-induced liver injury and that treatment with anti-TNF-alpha antibody may be therapeutically useful in this disease.

Contribution of Fas ligand to T cell-mediated hepatic injury in mice

BACKGROUND & AIMS

Fas has been implicated in liver damage. The aim of this study was to investigate the role of its ligand to induce hepatocyte death and liver damage in T cell-dependent hepatitis.

METHODS

Fas ligand-mediated lysis of primary hepatocytes from C57BL/6 wild-type, Fas ligand-deficient gld, and Fas-deficient lpr mice and concanavalin A-induced hepatitis in these mice were assessed.

RESULTS

Freshly isolated hepatocytes from wild-type or gld mice, but not those from lpr mice, were susceptible to Fas ligand-mediated lysis. When concanavalin A was intravenously administered into wild-type mice, they developed acute hepatic injury with massive degenerative changes in hepatocytes. In contrast, both gld and lpr mice had lower aminotransferase levels with milder histological changes. Reverse-transcription polymerase chain reaction and flow cytometric analysis showed that Fas ligand was induced in the liver shortly after the concanavalin A injection and was predominantly expressed on intrahepatic T cells. Administration of monoclonal antibody neutralizing mouse Fas ligand could reduce the aminotransferase increase.

CONCLUSIONS

The results indicate that Fas ligand plays a role in the T cell-dependent hepatitis induced by concanavalin A administration.

[Efficacy of interferon alpha in primary prevention of preneoplastic lesions in a transgenic murine model of hepatocellular carcinoma related to the interaction between woodchuck hepatitis viruses and c-myc oncogene]

OBJECTIVES

C-myc oncogene overexpression by near insertion of hepatitis B virus is important in woodchuck hepatocarcinogenesis. This DNA fragment was transferred in mice who developed hepatocellular carcinoma via preneoplastic lesions. In the present study, we tested the preventive effect of alpha interferon on the incidence of hepatocyte dysplasia.

METHODS

Human recombinant alpha interferon hybrid B/D was continuously administered at increasing doses (0 to 10,000 IU/g) in a transgenic mouse model. One cohort was treated from day 21 to day 80. A histological liver examination was performed and the transgene expression was assessed by hybridization with or without previous genic amplification, and by indirect immunofluorescence.

RESULTS

At day 15, histological liver examination was normal. Interferon treatment decreased the expression of viral sequences, but not of c-myc. At day 80, interferon treatment resulted in a reduction of the incidence and severity of dysplasic lesions, and a marked decrease in c-myc overexpression.

CONCLUSION

In this transgenic mouse model, alpha interferon treatment decreased the incidence and severity of precancerous lesions, due to a reduction in c-myc overexpression. This prophylaxis could be of interest in human hepatocarcinogenesis where c-myc overexpression is frequent.