Inhibitory effects of nodakenin on inflammation and cell death in lipopolysaccharide-induced liver injury mice

BACKGROUND

Nodakenin, a coumarin glucoside isolated from the roots of Angelica biserrata, has been reported to have anti-inflammatory, antibacterial, anticancer effects. However, despite these studies, the potential liver protective effects of nodakenin in inflammatory liver injury models have not been reported.

METHODS

A mouse model of inflammatory liver injury was induced by injection of lipopolysaccharide (LPS) (15 mg/kg, intraperitoneally (i.p)). Liver tissue AST, ALT, ROS, T-GSH and T-SOD were analyzed by ELISA. The concentrations of TNF-α, IL-6, and IL-1β in serum of LPS-induced inflammatory liver injury mice were analyzed. The mRNA expression levels of GPx1, catalase, SOD1, SOD2, TNF-α, IL-6, IL-1β, iNOS and COX-2 were analyzed using real-time PCR. The expressions of MAPK, IRF3, NF-κB, Nrf2, HO-1, caspase-3 and caspase-7 were analyzed using western blotting. Liver tissue was stained with IHC to confirm NF-κB, Nrf-2, HO-1, caspase-3, Bax, and Bcl2. Tunnel analysis was performed to confirm the fragmented nuclear DNA characteristics of apoptosis.

RESULTS

The administration of nodakenin (10 and 30 mg/kg) reduced serum aminotransferase levels compared to LPS-induced liver damage and significantly improved the oxidative state of liver tissue and pathological damage. Moreover, inhibited the phosphorylation of transforming growth factor beta (TGF-β)-activated kinase (TAK)-1 in LPS-induced inflammatory liver injury model, and significantly inhibited the transcriptional of nuclear factor-kappa B (NF-kB) and the secretion of pro-inflammatory mediators. In addition nodakenin pre-treatment also attenuated hepatocyte death by regulating apoptosis-related mitochondrial proteins, such as cysteinyl aspartate specific proteinase 3 (caspase 3), poly (ADP-ribose) polymerase (PARP), B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X (Bax).

CONCLUSION

Our findings suggest that nodakenin has anti-inflammatory, anti-oxidant and anti-apoptotic activity and may be an adjunctive prevention agent for liver injury.

Evaluation of metallothionein and Ki-67 expression in chronic cholangiohepatitis in cats

Chronic cholangiohepatitis (CCH) is a common pathological condition in cats with a guarded prognosis and unknown etiology. Recently, in human medicine, there has been increased interest in enhancing liver defense mechanisms as an effective treatment strategy to control liver diseases that have a poor prognosis. Metallothionein (MT) is a ubiquitous protein, which has been widely researched for its role in liver defense through heavy metal detoxification, neutralization of reactive oxygen species, and liver regeneration. In this study, immunohistochemistry was used to evaluate the role of MT in CCH and hepatocellular regeneration in 34 cats histologically diagnosed with this condition by assessing the correlation between hepatocellular MT and Ki-67 (marker for cellular proliferation) expression with histological parameters of CCH, such as inflammation, fibrosis, and bile duct proliferation. Statistical analysis was performed using the Spearman-rank correlation test. A significant positive correlation was observed between inflammation and the number of MT-positive hepatocytes (r = 0.36, P = 0.03) and MT labelling intensity (r = 0.37, P = 0.03). In 16 of 34 cases (47%) MT labelling intensity was noted to be pronounced towards the centrilobular zone and very weak or absent towards the portal zone. The results suggest that MT is induced in the liver during chronic inflammatory conditions, which could be speculated as a host defensive mechanism to protect the liver from inflammation-mediated liver injury. Therapeutic interventions utilizing MT, therefore, may have a positive effect on cats with chronic cholangiohepatitis.

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.

The protein tyrosine kinase SYK regulates the alternative p38 activation in liver during acute liver inflammation

Two distinct p38 signaling pathways, classical and alternative, have been identified to regulate inflammatory responses in host defense and disease development. The role of alternative p38 activation in liver inflammation is elusive, while classical p38 signaling in hepatocytes plays a role in regulating the induction of cell death in autoimmune-mediated acute liver injury. In this study, we found that a mutation of alternative p38 in mice augmented the severity of acute liver inflammation. Moreover, TNF-induced hepatocyte death was augmented by a mutation of alternative p38, suggesting that alternative p38 signaling in hepatocytes contributed more significantly to the pathology of acute liver injury. Furthermore, SYK-Vav-1 signaling regulates alternative p38 activation and the downregulation of cell death in hepatocytes. Therefore, it is suggested that alternative p38 signaling in the liver plays a critical role in the induction and subsequent pathological changes of acute liver injury. Collectively, our results imply that p38 signaling in hepatocytes plays a crucial role to prevent excessive liver injury by regulating the induction of cell death and inflammation.

Hepatocyte expression and prognostic importance of senescence marker p21 in liver histopathology samples from dogs with chronic hepatitis

BACKGROUND

Chronic hepatitis (CH) occurs commonly in dogs but is associated with a variable and largely unpredictable prognosis. p21, a cell-cycle inhibitor and marker of cellular senescence, is upregulated in human liver disease and is a better prognostic marker than histological or clinical scoring systems.

OBJECTIVE

To quantify hepatocyte p21 immunopositivity in histopathology samples from dogs with CH and determine its association with outcome.

ANIMALS

Twenty-six client-owned dogs with histologically confirmed CH, and 15 dogs with normal liver histology.

METHODS

Medical records and liver histopathology samples were retrospectively reviewed to identify cases of CH. Immunohistochemistry for p21 was performed on all samples and hepatocyte immunopositivity was visually quantified. Relationships between p21 and dog age and dog survival time were statistically evaluated.

RESULTS

Hepatocyte p21 immunopositivity in dogs with CH was high (median percentage of positive hepatocytes: 90%, range: 20%-98%) and exceeded 70% in 23/26 cases with no association with age. In control dogs, p21 immunopositivity was low (≤15% positive hepatocytes in 12/15 cases) and was positively correlated with age (rs  = 0.63; P = .011). Dogs with p21 immunopositivity exceeding 91.8% (upper tercile) had significantly shorter survival compared to dogs with less than 88.9% immunopositivity (lowest tercile; 218 versus 874 days, P = .006). Increasing hepatocyte p21 immunopositivity was significantly negatively associated with survival time (HR 4.12; 95% CI 1.34-12.63; P = .013).

CONCLUSIONS AND CLINICAL IMPORTANCE

Marked p21 immunopositivity in dogs with CH might be indicative of widespread hepatocellular senescence. A significant association with survival time also suggests a potential value for p21 quantification in determining prognosis.

Treatment effect of a flavonoid prescription on duck virus hepatitis by its hepatoprotective and antioxidative ability

CONTEXT

Duck virus hepatitis (DVH) caused by duck hepatitis A virus type 1 (DHAV-1) is an acute and lethal disease of young ducklings. However, there is still no effective drug to treat DVH.

OBJECTIVE

This study assessed the curative effect on DVH of a flavonoid prescription baicalin-linarin-icariin-notoginsenoside R1 (BLIN) as well as the hepatoprotective and antioxidative effects of BLIN.

MATERIALS AND METHODS

MTT method was used to test the anti-DHAV-1 ability of BLIN in vitro. We then treated ducklings by BLIN (3 mg per duckling, once a day for 5 days) to evaluate the in vivo efficacy. To study the hepatoprotective and antioxidative roles of BLIN in its curative effect on DVH, we investigated the hepatic injury evaluation biomarkers and the oxidative stress evaluation indices of the ducklings.

RESULTS

On duck embryonic hepatocytes, DHAV-1 inhibitory rate of BLIN at 20 μg/mL was 69.3%. The survival rate of ducklings treated by BLIN was about 35.5%, which was significantly higher than that of virus control (0.0%). After the treatment of BLIN, both the hepatic injury and the oxidative stress of infected ducklings alleviated. At the same time, a significant positive correlation (p < 0.05) existed between the hepatic injury indices and the oxidative stress indices.

CONCLUSIONS

BLIN showed a significant curative effect on DVH. The antioxidative and hepatoprotective effects of BLIN made great contributions to the treatment of DVH. Furthermore, BLIN is expected to be exploited as a new drug for the clinical treatment of DVH.

Gene expression patterns in the progression of canine copper-associated chronic hepatitis

Copper is an essential trace element, but can become toxic when present in abundance. The severe effects of copper-metabolism imbalance are illustrated by the inherited disorders Wilson disease and Menkes disease. The Labrador retriever dog breed is a novel non-rodent model for copper-storage disorders carrying mutations in genes known to be involved in copper transport. Besides disease initiation and progression of copper accumulation, the molecular mechanisms and pathways involved in progression towards copper-associated chronic hepatitis still remain unclear. Using expression levels of targeted candidate genes as well as transcriptome micro-arrays in liver tissue of Labrador retrievers in different stages of copper-associated hepatitis, pathways involved in progression of the disease were studied. At the initial phase of increased hepatic copper levels, transcriptomic alterations in livers mainly revealed enrichment for cell adhesion, developmental, inflammatory, and cytoskeleton pathways. Upregulation of targeted MT1A and COMMD1 mRNA shows the liver's first response to rising intrahepatic copper concentrations. In livers with copper-associated hepatitis mainly an activation of inflammatory pathways is detected. Once the hepatitis is in the chronic stage, transcriptional differences are found in cell adhesion adaptations and cytoskeleton remodelling. In view of the high similarities in copper-associated hepatopathies between men and dog extrapolation of these dog data into human biomedicine seems feasible.

Copper-associated Chronic Hepatitis and Cirrhosis in a European Shorthair Cat

A 2-year-old, castrated, male European Shorthair cat was presented with inappetence, vomiting, and fever. Ascites and an irregularly nodular liver were observed on laparotomy; in view of the poor prognosis, the animal was euthanatized. Histopathologic examination of the liver showed a chronic hepatitis with cirrhosis associated with massive accumulation of copper in hepatocytes and macrophages, particularly in the fibrotic areas between the regenerative nodules. Electron microscopy and energy-dispersive X-ray analysis revealed lysosomal accumulation of copper in the hepatocytes. Analytical determination showed very high copper concentrations in the liver. No evidence for increased dietary or environmental copper could be found. This and the pattern of hepatic copper storage, the associated inflammation and fibrosis, strongly suggest a primary copper storage disorder.

[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.

Pathological role of interleukin-17 in poly I:C-induced hepatitis

Immune-mediated responses were the main causes of liver damage during viral hepatitis, and recently viral RNA mimetic Poly I:C was used to induce a NK cell-dominated acute hepatitis. Interleukin-17A (IL-17A), the cytokine tightly associated with various autoimmune diseases, was known to play protective or pathological roles in LPS and ConA-induced hepatitis. However, its role in NK cell-mediated acute hepatitis remains unknown. Here we demonstrated that Poly I:C treatment triggered IL-17A production from hepatic γδT cells. Neutralizing IL-17A by monoclonal antibodies reduced Poly I:C-induced intrahepatic inflammatory responses and the liver injury through decreased accumulation, activation and cytolytic activity of NK cells in the liver. Furthermore, Poly I:C didn't trigger IL-17A secretion from γδT cells directly, and Kuppfer cells were demonstrated to be the accessory cell that can secrete IL-23. Finally, our findings demonstrated a pathological role of IL-17A and γδT cells in Poly I:C-induced acute hepatitis, which provides novel insights into viral infection-induced hepatitis and may serve as potential target in clinic immunotherapy against these disease.

Scavenger receptor A restrains T-cell activation and protects against concanavalin A-induced hepatic injury

Negative feedback immune mechanisms are essential for maintenance of hepatic homeostasis and prevention of immune-mediated liver injury. We show here that scavenger receptor A (SRA/CD204), a pattern recognition molecule, is highly up-regulated in the livers of patients with autoimmune or viral hepatitis, and of mice during concanavalin A (Con A)-induced hepatitis (CIH). Strikingly, genetic SRA ablation strongly sensitizes mice to Con A-induced liver injury. SRA loss, increased mortality and liver pathology correlate with excessive production of IFN-γ and heightened activation of T cells. Increased liver expression of SRA primarily occurs in mobilized hepatic myeloid cells during CIH, including CD11b(+) Gr-1(+) cells. Mechanistic studies establish that SRA on these cells functions as a negative regulator limiting T-cell activity and cytokine production. SRA-mediated protection from CIH is further validated by adoptive transfer of SRA(+) hepatic mononuclear cells or administration of a lentivirus-expressing SRA, which effectively ameliorates Con A-induced hepatic injury. Also, CIH and clinical hepatitis are associated with increased levels of soluble SRA. This soluble SRA displays a direct T-cell inhibitory effect and is capable of mitigating Con A-induced liver pathology.

CONCLUSION

Our findings demonstrate an unexpected role of SRA in attenuation of Con A-induced, T-cell-mediated hepatic injury. We propose that SRA serves as an important negative feedback mechanism in liver immune homeostasis, and may be exploited for therapeutic treatment of inflammatory liver diseases.

Regulation of the development of acute hepatitis by IL-23 through IL-22 and IL-17 production

IL-23 plays a critical role in the expansion of highly proinflammatory Th17 cells secreting IL-17 and IL-22. Recently, we demonstrated that Notch signaling drives IL-22 secretion through the aryl hydrocarbon receptor (AHR) and plays a protective role in Con A-induced hepatitis. In this study, we investigated the role of IL-23 in hepatitis using IL-23p19- and IL-17-deficient mice. In WT mice, the injection of Con A induced the upregulation of various cytokines, which included IL-23, IL-22, IL-17, IFN-γ and TNF-α. In IL-23p19-deficient mice, exacerbated hepatitis was observed and serum IL-22 and IL-17 levels were greatly reduced, whereas in IL-17-deficient mice, ameliorated hepatitis was observed. The injection of exogenous IL-22 protected p19-deficient mice from hepatitis, whereas the injection of exogenous IL-23 significantly increased the serum levels of not only IL-22 but also IL-17, and less effectively protected against hepatitis in IL-17-dependent and -independent manners. Finally, it was revealed that STAT3, STAT4 and Notch contributed to the production of both the cytokines, and that the AHR was important only for IL-22 production in response to Con A and IL-23 in liver mononuclear cells. These results suggest that IL-23 plays a protective role in hepatitis through IL-22 production and also a pathological role via IL-17-dependent and -independent mechanisms.

[Hepatoprotective effect of thiophane in rats with experimental carbon tetrachloride-induced hepatitis]

A hepatoprotective effect of thiophan was studied on the model of carbon tetrachloride-induced hepatitis in rats. Therapeutic administration of thiophan repairs the antitoxic function of liver, normalizes cytolysis marker activity, and improves the synthetic function of liver and the carbohydrate and lipid metabolism. The hepatoprotective activity of thiophan is similar to effect of silimarin.

[Effect of citrate on oxidative status of rats tissues in experimental toxic hepatitis]

The effect of citrate free-radical oxidation intensity and aconitate hydratase, superoxide dismutase and catalase activities in liver and blood serum of rats with experimental toxic hepatitis has been investigated. Citrate administration to rats with hepatitis decreased biochemiluminescence parameters and conjugated diene content in rats tissues, increased under conditions of CCl4-induced liver damage. At the same time aconitase activity, decreased at the pathology, increases. The superoxide dismutase and catalase activities increased in at experimental toxic hepatitis, tended towards control values after citrate administration.

[Seasonal variations of nucleic acid content in an experiment on non-pharmacological correction of the hepatic function]

This experiment was preformed on an animal model of CCl4 hepatitis using 320 Wistar rats. The animals underwent combined effect of saprogel and a magnetic field during different seasons. It was shown that non-medicamentous treatment of experimental CCl4 hepatitis had the most pronounced beneficial effect on the synthetic liver function in the winter time. An appreciable suppression of the hepatic function was documented in the spring.

Characterisation of the hepatic progenitor cell compartment in normal liver and in hepatitis: an immunohistochemical comparison between dog and man

The liver progenitor cell compartment in the normal canine liver and in spontaneous canine acute (AH) and chronic hepatitis (CH) was morphologically characterised and compared to its human equivalents. Immunohistochemistry was performed for cytokeratin-7 (CK7), human hepatocyte marker (Hep Par 1), multidrug resistance-associated protein-2 (MRP2), and breast cancer resistance protein (BCRP) on paraffin and frozen sections from canine and human tissues. Normal liver showed similar morphology and immunohistochemical reaction of the progenitor cell compartment/canal of Hering in man and dog. In addition, a ductular reaction, comparable in terms of severity, location and immunohistochemical characteristics, was observed in canine and human AH and CH. CK7 was a good marker for canine progenitor cells, including intermediate cells, which were positively identified in cases of AH and CH. In both species, BCRP was expressed in both hepatocytes and bile ducts of the normal liver, and in ductular reaction in AH and CH. MRP2 detected bile canalicular membranes in man and dog. These findings underline the similarities between canine and human liver reaction patterns and may offer mutual advantage for comparative research in human and canine spontaneous liver diseases.

[Effect of phytopreparation Narcophyt on choleretic reaction in white rats with experimental hepatitis]

Experiments on white rats show that the phytopreparation Narcophyt possesses choleretic activity. In rats with experimental hepatitis induced by ethanol, the course of therapeutic and prophylactic administration of Narcophyt favorably influenced the bile secreting function of the liver, accelerated bile secretion, stimulated the synthesis and secretion of cholates, as well as the secretion of bilirubin and excretion of cholesterol. The cholagogic effect of Narcophyt was comparable with that of the reference drug cholosas.

[Hepatoprotective effect of Gossipium hirsutum extract on acute experimental hepatitis on rat liver injury]

OBJECTIVE

To investigate the protective effect on the mice acute experimental hepatic injury by Flos Gossypium herbaceum extracts (FGF-I, FGF-II).

METHOD

Experimental hepatic injury model was established by a single intraperitoneal injection of 350 mg x kg(-1) D-CalN in Wistar rats. Serum samples for alanine aminotransferase (ALT), aspartate transferase (AST) level and liver homogenate samples for super oxide dismutase (SOD), malondialdehyde (MDA), Glutathione peroxidese (GSH-PX) activities were assayed.

RESULT

For acute experimental hepatic injury, FGF-I and FGF-II significantly decrease the serum transaminase activities (P < 0.01). FGF-I increased the SOD activities (P < 0.01), and decreased MDA content only for 50 mg x kg(-1) FGF-I (P < 0.05), no effect on GSH-PX activity was found for them. FGF-II increased the SOD and GSH-PX activity (P < 0.05) with decreased MDA content (P < 0.05).

CONCLUSION

FGF-I and FGF-II showed significant protective action in mice experimental hepatic injury.

Methionine deficiency and hepatic injury in a dietary steatohepatitis model

Methionine (Meth) is an essential amino acid involved in DNA methylation and glutathione biosynthesis. We examined the effect of Meth on the development of steatohepatitis. Rats were fed (five weeks) amino acid-based Meth-choline-sufficient (A-MCS) or total deficient (MCD) diets and gavaged daily (two weeks) with vehicle (B-vehicle/MCD), or Meth replacement (C-Meth/MCD). To assess the effect of short-term deficiency, after three weeks one MCS group was fed a deficient diet (D-MCS/MCD). Animals fed the deficient diet for two weeks lost (29%) weight and after five weeks weighed one third as much as those on the sufficient diet, and also developed anemia (P < 0.01). Hepatic transaminases progressively increased from two to five weeks (P < 0.01), leading to severe hepatic pathology. Meth administration normalized hematocrit, improved weight (P < 0.05), and suppressed abnormal enzymes activities (P < 0.01). Meth administration improved blood and hepatic glutathione (GSH), S-adenosylmethionine (SAMe), and hepatic lesions (P < 0.01). The deficient diet significantly upregulated proinflammatory and fibrotic genes, which was ameliorated by Meth administration. These data support a pivotal role for methionine in the pathogenesis of the dietary model of Meth-choline-deficient (MCD) steatohepatitis (NASH).

Hepatic 64Cu excretion in Dobermanns with subclinical hepatitis

To investigate whether Dobermanns have impaired copper excretion an intravenous radioactive copper isotope ((64)Cu) was used as a tracer. Five patients and eight normal dogs (5 normal Dobermanns and 3 Beagles) were studied. The five female Dobermann patients had a subclinical hepatitis and an increased hepatic copper concentration (median 822mg/kg, range 690-1380mg/kg dry matter). The normal dogs, five Dobermanns and three Beagles, had no abnormal liver histopathology and hepatic copper concentrations were considered normal (Dobermanns; median 118mg/kg, range 50-242mg/kg dry matter; Beagles; median 82mg/kg, range 50-88mg/kg dry matter). Cholestasis was excluded in all dogs by means of a (99m)Tc-Bis-IDA hepatobiliary scintigraphy. Plasma clearance of (64)Cu was comparable in all dogs with no statistically significant differences. The excretion of (64)Cu into the bile, although not statistically significant, was less for the Dobermanns with subclinical hepatitis compared to the normal dogs. The findings suggest that impaired copper excretion may play a role in the aetiology of chronic hepatitis in the Dobermann.

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.

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.

Rosiglitazone attenuates suppression of RXRalpha-dependent gene expression in inflamed liver

BACKGROUND/AIMS

A recently determined target of lipopolysaccharide (LPS) and cytokine signaling in liver is the central Type II nuclear receptor (NR) heterodimer partner, retinoid X receptor alpha (RXRalpha). We sought to determine if Rosiglitazone (Rosi), a peroxisome proliferator activated receptor gamma (PPARgamma) agonist with anti-inflammatory properties, can attenuate LPS and cytokine-induced molecular suppression of RXRalpha-regulated genes.

METHODS

In vivo, mice were gavage-fed Rosi for 3 days, prior to intraperitoneal injection of LPS, followed by harvest of liver and serum. In vitro, HepG2 cells were treated with IL-1beta, +/- short-term Rosi pretreatment. RNA was analyzed by quantitative RT-PCR, while nuclear and cytoplasmic proteins were analyzed by immunoblotting and gel shifts.

RESULTS

Rosi attenuated LPS-mediated suppression of RNA levels of several Type II NR-regulated genes, including bile acid transporters and the major drug metabolizing enzyme, Cyp3a11, without affecting cytokine expression, suggesting a novel, direct anti-inflammatory effect in hepatocytes. Rosi suppressed the inflammation-induced nuclear export of RXRalpha, in both LPS-injected mice and IL-1beta-treated HepG2 cells, leading to maintenance of nuclear RXRalpha levels and heterodimer binding activity.

CONCLUSIONS

Rosi directly attenuates the suppressive effects of inflammation-induced cell signaling on nuclear RXRalpha levels in liver.

Inhibition of oxidative stress and cytokine activity by curcumin in amelioration of endotoxin-induced experimental hepatoxicity in rodents

The present study is aimed at investigating the effect of curcumin (CMN) in salvaging endotoxin-induced hepatic dysfunction and oxidative stress in the liver of rodents. Hepatotoxicity was induced by administering lipopolysaccharide (LPS) in a single dose of 1 mg/kg intraperitoneally to the animals, which were being treated with CMN daily for 7 days. Liver enzymes serum alanine aminotransferase (ALT), serum aspartate aminotransferase (AST) and alkaline phosphatase (ALP), total bilirubin and total protein were estimated in serum. Oxidative stress in liver tissue homogenates was estimated by measuring thiobarbituric acid reactive substances (TBARS), glutathione (GSH) content and superoxide dismutase (SOD) activity. Serum and tissue nitrite was estimated using Greiss reagent and served as an indicator of NO production. A separate set of experiments was performed to estimate the effect of CMN on cytokine levels in mouse serum after LPS challenge. LPS induced a marked hepatic dysfunction evident by rise in serum levels of ALT, AST, ALP and total bilirubin (P < 0.05). TBARS levels were significantly increased, whereas GSH and SOD levels decreased in the liver homogenates of LPS-challenged rats. CMN administration attenuated these effects of LPS successfully. Further CMN treatment also regressed various structural changes induced by LPS in the livers of rats and decreased the levels of tumour necrosis factor-alpha and interleukin-6 in mouse plasma. In conclusion, these findings suggest that CMN attenuates LPS-induced hepatotoxicity possibly by preventing cytotoxic effects of NO, oxygen free radicals and cytokines.

Transforming growth factor beta-1 signalling in canine hepatic diseases: new models for human fibrotic liver pathologies

BACKGROUND/AIMS

The purpose of this study was to validate spontaneous chronic hepatitis and cirrhosis in dogs as a potential large animal model for fibrotic liver disease in humans by evaluating their molecular pathophysiology.

METHODS

Transforming growth factor-beta1 (TGF-beta1) signalling was analysed in liver samples of dogs with acute hepatitis (AH), chronic hepatitis (CH), cirrhosis (CIRR), and a specific form of cirrhosis, lobular dissecting hepatitis (LDH), in comparison with human cirrhotic samples from alcohol abuse (ALC) and hepatitis C (HC).

RESULTS

Canine samples were investigated with quantitative real-time PCR (Q-PCR) and Western blotting on TGF-beta1 signalling including Smad2/3 phosphorylation. Immunohistochemistry on collagens I and III was performed. Q-PCR showed an increase in TGF-beta1 levels and downstream effector gene products in CH, LDH, and CIRR. The same fibrotic diseases also showed an increase in phosphorylated Smad2/3 and a higher deposition of collagens I and III. In contrast, in AH neither active TGF-beta1 signalling nor collagen deposition was observed. Western blot analysis on human ALC and HC indicated a high similarity with canine samples in TGF-beta1 expression and Smad2/3 phosphorylation.

CONCLUSIONS

Our results demonstrate that fibrosis in spontaneous dog liver diseases is highly comparable to their human counterparts and might serve as models for anti-fibrotic strategies.

Reactive oxygen species modify oligosaccharides of glycoproteins in vivo: a study of a spontaneous acute hepatitis model rat (LEC rat)

The Long-Evans Cinnamon (LEC) rat, an animal model of Wilson's disease, spontaneously develops hepatitis as the result of abnormal copper accumulation in liver. The findings of this study show that copper, hydrogen peroxide, and lipid peroxides accumulate to drastically high levels in LEC rat serum in acute hepatitis but not chronic hepatitis. The effect of these reactive oxygen species (ROS) on oligosaccharides of glycoproteins in the LEC rat serum was examined. Lectin blot and lectin ELISA analyses showed that sialic acid and galactose residues of serum glycoproteins including transferrin were decreased in acute hepatitis. Further analyses of oligosaccharide structures of transferrin demonstrated that di-sialylated and asialo-agalacto biantennary sugar chains, but not tri-sialylated sugar chain, exist on transferrin in the acute hepatitis rats. In addition, treatment of non-hepatitis rat serum with copper ions and hydrogen peroxide decreased tri-sialylated sugar chain of the normal transferrin and increased di-sialylated and asialo-agalacto biantennary sugar chains. This is the first evidence to show that ROS result in the cleavage of oligosaccharides of glycoproteins in vivo, and indicate this cleavage of oligosaccharides may contribute the development of acute hepatitis.

Lupus-prone NZBWF1/J mice, defective in cytokine signaling, are resistant to fumonisin hepatotoxicity despite accumulation of liver sphinganine

Fumonisin B1 (FB1) is a mycotoxin produced by Fusarium verticillioides, commonly present in corn and other cereals. Exposure to FB1 causes organ-specific diseases in various species, e.g., equine leukoencephalomalacia and porcine pulmonary edema; in mice the response is hepatotoxicity. We earlier reported that ceramide synthase inhibition by FB1, the initial biochemical effect of this mycotoxin, results in modulation of cytokine network in response to accumulated free sphingoid bases. In the current study we used NZB/NZW-F1 (NZBW) mice that have modified cytokine expression and develop lupus beginning at 5 months of age. The NZBW and C57BL/6J (CBL) mice (appropriate control) were given five daily subcutaneous injections of either saline or 2.25 mg FB1/kg/day and euthanized 24 h after the last treatment. Peripheral leukocyte counts were higher after exposure to FB1 in CBL but not in NZBW. FB1 treatment caused increases of plasma alanine aminotransferase and aspartate aminotransferase activity in CBL mice indicating hepatotoxicity; no elevation of circulating liver enzymes was recorded in NZBW mice. Hepatotoxic responses were confirmed by microscopic evaluation of apoptotic cells. The FB1-induced proliferation of cells observed in CBL strain was abolished in NZBW animals. The sphinganine accumulation in liver after FB1 was equal in both strains of mice. The NZBW strain lacked the FB1-induced increases in the expression of liver tumor necrosis factor alpha, interferon gamma, receptor interacting protein (RIP), and tumor necrosis factor alpha-related apoptosis-inducing ligand (TRAIL), observed in CBL. Results confirmed our hypothesis that initial altered sphingolipid metabolism caused by FB1 leads to perturbation of liver cytokine network and ultimate cellular injury; the mice deficient in cytokine signaling are refractory to FB1 hepatotoxicity.

The kinase inhibitor imatinib mesylate inhibits TNF-{alpha} production in vitro and prevents TNF-dependent acute hepatic inflammation

Imatinib exerts potent antileukemic effects in vitro and in vivo. Despite its well known antitumor activity, the potential of imatinib for the treatment of inflammatory diseases remains elusive so far. Our current report provides strong evidence that imatinib has potent antiinflammatory effects. It potently inhibits LPS- and Con A-induced TNF-alpha production by human myeloid cells in vitro (peripheral blood mononuclear cells, CD14-selected monocytes, and monocyte-derived macrophages). Of note, the production of the antiinflammatory cytokine IL-10 was not significantly regulated by imatinib. In line with this observation, phosphorylation of IkappaB and subsequent DNA binding of NF-kappaB, which is critically involved in TNF-alpha, but not IL-10 expression, was reduced by imatinib. Using several murine models of acute hepatitis, we could corroborate our in vitro findings, as imatinib prevented macrophage- and TNF-alpha-dependent inflammatory damage of the liver induced by injection of either Con A or d-galactosamine/LPS by inhibition of hepatic TNF-alpha production. Of note, d-galactosamine/TNF-induced hepatitis was not affected, showing that imatinib does not directly inhibit TNF-alpha-induced hepatocellular cell death. These findings suggest a potent antiinflammatory role of imatinib by modulation of TNF-alpha production in monocytes/macrophages. This observation might be of therapeutic value for the treatment of TNF-mediated diseases.

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.

Modifications in P62 occur due to proteasome inhibition in alcoholic liver disease

P62 is capable of binding the polyubiquitin chain that targets proteins for degradation by the proteasome through its ubiquitin associated domain (UBA). Immunostaining of hepatocytes from human liver with alcoholic hepatitis showed colocalization of ubiquitin and P62 in Mallory bodies. Rats fed ethanol chronically and their controls showed that P62 is colocalized with the proteasome in hepatocytes as shown by confocal microscopy. P62 cosedimented with 26S proteasomes isolated from livers of control and alcohol fed rats. P62 was increased in the 26S proteasome fraction when the proteasome chymotrypsin-like (ChT-L) activity decreased in rats fed ethanol. PS-341, a potent proteasome inhibitor was used to compare the inhibition of the proteasome with the inhibition which occurs with ethanol feeding. P62 protein levels were also increased in the purified proteasome fraction of rats given PS-341. This data indicates that modifications in P62 occur due to proteasome inhibition in experimental alcoholic liver disease.

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.

Melatonin-selenium nanoparticles protects liver against immunological injury induced by bacillus Calmette-Guerin and lipopolysaccharide

AIM

Melatonin-selenium nanoparticle (MT-Se), a novel complex, was synthesized by preparing selenium nanoparticles in a melatonin medium. The present investigation was designed to determine the protective effects of MT-Se against immunological liver injury in mice induced by bacillus Calmette-Guerin (BCG)/lipopolysaccharide (LPS).

METHODS

The model of immunological liver injury in mice was prepared. The levels of alanine aminotransferase, aspartate amino-transferase, nitric oxide (NO) in serum, malondialdehyde content, superoxide dismutase (SOD), and glutathione peroxidase (GSH-px) activities in a liver homogenate were assayed by spectrophotometry. The content of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) were determined by ELISA. The splenocyte proliferation was assayed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) dye reduction. Meanwhile, a hepatic pathological examination was observed.

RESULTS

In the BCG/LPS-induced hepatic injury model, MT-Se administered at doses of 5, 10, or 20 mg/kg to the BCG/LPS-treated mice for 10 d significantly reduced the increase in serum aminotransferase, reduced the severe extent of hepatic cell damage and the immigration of inflammatory cells. It also attenuated the increase in the content of thiobarbituric acid-reactive substances and enhanced the decrease in activities of SOD and GSH-px. In contrast, the treatment with MT-Se suppressed the increase in NO level in both the serum and liver tissue. Furthermore, MT-Se significantly lowered an increase in TNF-alpha and IL-1beta levels in the liver and inhibited the production of TNF- alpha and IL-1beta by peritoneal macrophages. A downregulation effect of MT-Se on splenocyte proliferation was also observed.

CONCLUSION

MT-Se showed a hepatic protective action on immunological liver injury in mice.

Heat shock protein 60 inhibits Th1-mediated hepatitis model via innate regulation of Th1/Th2 transcription factors and cytokines

Extracellular heat shock protein 60 (HSP60) has been considered a proinflammatory danger signal. Yet, HSP60 can also down-regulate experimental immune arthritis and diabetes models by specific inhibition of Th1-like responses. We now report that HSP60 in vitro differentially modulates the expression of Th1/Th2 transcription factors in human T cells: HSP60 down-regulates T-bet, NF-kappaB, and NFATp and up-regulates GATA-3, leading to decreased secretion of TNF-alpha and IFN-gamma and enhanced secretion of IL-10. These effects depended on TLR2 signaling and could not be attributed to LPS or to other contaminants. In BALB/c mice, HSP60 in vivo inhibited the clinical, histological, and serological manifestations of Con A-induced hepatitis associated with up-regulated T cell expression of suppressor of cytokine signaling 3 and GATA-3 and down-regulated T-bet expression. These results provide a molecular explanation for the effects of HSP60 treatment on T cell inflammation via innate regulation of the inflammatory response.

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.

Enhanced inducible nitric oxide synthase expression and nitrotyrosine accumulation in experimental granulomatous hepatitis caused by Toxocara canis in mice

The involvement of inducible nitric oxide synthase (iNOS) and nitrotyrosine (NT) in pathogenesis of toxocaral granulomatous hepatitis (TGH) in a murine host was quantitatively determined by biochemical, parasitological, pathological, and immunohistochemical assessments in a 42-week investigation. Mice were sacrificed for serum collection and histological processing as well as acid-pepsin digestion of the liver in a larval recovery study. Significantly increased levels of total serum NO were found in the trial, indirectly suggesting iNOS activation in the liver. iNOS reactivity was predominantly observed in infiltrating leucocytes in lesions and normal and apocrine-like cholangiocytes; in contrast, hepatocytes and multinucleated giant cells showed negative cytoplasmic staining in TGH. Strong iNOS-like reactivity was also detected on the body wall of larvae. The locations of NT reactivity were nearly identical to those of iNOS expression; infiltrating leucocytes or cholangiocytes stained for iNOS were also stained for NT in TGH. Enhanced iNOS expression, but not invading larvae (r = 0.256, P = 0.211), seemed to play a certain role in pathological damage in TGH due to a significant correlation between iNOS expression and serum alanine aminotransferase (ALT) levels (r =0.593, P = 0.021) in the trial. Our present results indicate a potential therapeutic strategy for treatment of GH caused by other nematodes through manipulation of iNOS expression.

Role of tumor necrosis factor-alpha in the development of spontaneous hepatic toxicity in Long-Evans Cinnamon rats

The objective of this study was to evaluate the potential role of TNF-alpha in the onset of acute hepatitis in the Long-Evans Cinnamon (LEC) rat, an animal model for inherited copper (Cu) toxicosis. In LEC rats, Cu is accumulated in the liver with age, and clinical signs of acute hepatitis were observed as, icterus, reduced body weight, nasal bleeding, dehydration, and reduced food intake at 12 weeks of age. Cellular changes such as apoptosis in the liver were evident in these rats with increasing age. Positive TNF-alpha and TNFR1 immunostainings were observed in hepatocytes and Kupffer cells in LEC rats. Hepatic levels of caspase-3 activity, TNF-alpha mRNA, and protein were also increased in LEC rats from 6 to 12 weeks of age as compared with control Long-Evans (LE) rats. The neutralization of TNF-alpha by passive immunization or the inhibition of caspase activity can block the apoptotic process initiated by TNF-alpha. In this study, we evaluated the effects of passive immunization of LEC rats with weekly administration of anti-rat TNF-alpha on Cu-induced acute hepatitis. This treatment resulted in a reduction of the percentage of apoptotic cells in the liver, decreased activity of caspase-3, and also in down-regulation of the TNF-alpha gene expression. Thus, these results suggest a major role for TNF-alpha on the pathogenesis of Cu-induced acute hepatitis in LEC rats.

IFN-gamma/STAT1 acts as a proinflammatory signal in T cell-mediated hepatitis via induction of multiple chemokines and adhesion molecules: a critical role of IRF-1

We have previously shown that IFN-gamma/STAT1 plays an essential role in concanavalin A (ConA)-induced T cell hepatitis via activation of apoptotic signaling pathways. Here we demonstrate that IFN-gamma/STAT1 also plays a crucial role in leukocyte infiltration into the liver in T cell hepatitis. After injection of ConA, leukocytes were significantly infiltrated into the liver, which was suppressed in IFN-gamma(-/-) and STAT1(-/-) mice. Disruption of the IFN regulatory factor-1 (IRF-1) gene, a downstream target of IFN-gamma/STAT1, abolished ConA-induced liver injury and suppressed leukocyte infiltration into the liver. Additionally, ConA injection induced expression of a wide variety of chemokines and adhesion molecules in the liver. Among them, expression of ICAM-1, VCAM-1, monokine induced by IFN-gamma (Mig), CC chemokine ligand-20, epithelial cell-derived neutrophil-activating peptide (ENA)-78, IFN-inducible T cell-alpha chemoattractant (I-TAC), and IFN-inducible protein-10 (IP-10) was markedly attenuated in IFN-gamma(-/-), STAT1(-/-), and IRF-1(-/-) mice. In primary mouse hepatocytes, Kupffer cells, and endothelial cells, in vitro treatment with IFN-gamma activated STAT1, STAT3, and IRF-1, and induced expression of VCAM-1, ICAM-1, Mig, ENA-78, I-TAC, and IP-10 mRNA. Induction of these chemokines and adhesion molecules was markedly diminished in STAT1(-/-) and IRF-1(-/-) hepatic cells compared with wild-type hepatic cells. These findings suggest that in addition to induction of apoptosis, previously well documented, IFN-gamma also stimulated hepatocytes, sinusoidal endothelial cells, and Kupffer cells partly via an STAT1/IRF-1-dependent mechanism to produce multiple chemokines and adhesive molecules responsible for promoting infiltration of leukocytes and, ultimately, resulting in hepatitis.

IL-6-deficient mice are susceptible to ethanol-induced hepatic steatosis: IL-6 protects against ethanol-induced oxidative stress and mitochondrial permeability transition in the liver

Interleukin-6 (IL-6)-deficient mice are prone to ethanol-induced apoptosis and steatosis in the liver; however, the underlying mechanism is not fully understood. Mitochondrial dysfunction caused by oxidative stress is an early event that plays an important role in the pathogenesis of alcoholic liver disease. Therefore, we hypothesize that the protective role of IL-6 in ethanol-induced liver injury is mediated via suppression of ethanol-induced oxidative stress and mitochondrial dysfunction. To test this hypothesis, we examined the effects of IL-6 on ethanol-induced oxidative stress, mitochondrial injury, and energy depletion in the livers of IL-6 (-/-) mice and hepatocytes from ethanol-fed rats. Ethanol consumption leads to stronger induction of malondialdehyde (MDA) in IL-6 (-/-) mice compared to wild-type control mice, which can be corrected by administration of IL-6. In vitro, IL-6 treatment prevents ethanol-mediated induction of reactive oxygen species (ROS), MDA, mitochondrial permeability transition (MPT), and ethanol-mediated depletion of adenosine triphosphate (ATP) in hepatocytes from ethanol-fed rats. Administration of IL-6 in vivo also reverses ethanol-induced MDA and ATP depletion in hepatocytes. Finally, IL-6 treatment induces metallothionein protein expression, but not superoxide dismutase and glutathione peroxidase in cultured hepatocytes. In conclusion, IL-6 protects against ethanol-induced oxidative stress and mitochondrial dysfunction in hepatocytes via induction of metallothionein protein expression, which may account for the protective role of IL-6 in alcoholic liver disease.

Expression of G1 phase-related cell cycle molecules in naturally developing hepatocellular carcinoma of Long-Evans Cinnamon rats

It has been shown that a variety of cell cycle-related proteins play important roles in the process of carcinogenesis including hepatocarcinogenesis. In the present study, we evaluated mRNA and protein expression of G1 phase-related cell cycle molecules in the process of hepatocarcinogenesis, using Long-Evans Cinnamon (LEC) rats, an animal model of hepatocellular carcinoma (HCC). The expression of cyclin D1, cyclin-dependent kinase 4 (Cdk4) and Cdk6 was measured quantitatively by real-time polymerase chain reaction. Cyclin D1 mRNA expression was increased significantly in chronic hepatitis liver compared with normal liver, and then decreased in HCC and the surrounding precancerous liver of LEC rats. Levels of Cdk4 mRNA were increased significantly in HCC compared to precancerous and chronic hepatitis livers. In contrast, mRNA levels of Cdk6 did not change significantly during hepatocarcinogenesis. We also evaluated the protein levels of these G1 phase-related cell cycle molecules by Western blot analyses and confirmed similar results. Total amounts of retinoblastoma protein (pRb) in the liver did not change significantly in the process of hepatocarcinogenesis in LEC rats. However, levels of phosphorylated pRb were increased markedly in the process of hepatocarcinogenesis, and the highest in HCC compared to precancerous, chronic hepatitis and normal livers. These results indicate that cyclin D1 may be involved in the regeneration of hepatocytes rather than hepatocarcinogenesis, while Cdk4 but not Cdk6 may play an important role in the development of HCC.

Acarbose attenuates experimental non-alcoholic steatohepatitis

The alpha-glucosidase inhibitor acarbose is beneficial in the prevention of type 2 diabetes. To determine whether it attenuates the commonly associated non-alcoholic steatohepatitis (NASH), we used an experimental NASH model. Rats were fed ad libitum a nutritionally adequate high fat diet (71% of calories as fat) with or without acarbose (200 mg/1000 calories) for 3 weeks. All rats given the high fat diet only developed typical NASH whereas acarbose attenuated several of the characteristic hepatic alterations of NASH: there was less steatosis and inflammation, with a significant reduction in the mRNA of the hepatic inflammatory cytokine TNF-alpha and of its protein. There was also a decrease in the CYP2E1 mRNA and in collagen, with similar trends for CYP2E1 protein and procollagen mRNA. Because acarbose attenuates many of the hepatic alterations associated with experimental NASH, it is now indicated to determine whether it exerts similar beneficial effects in patients afflicted by this disease.

Tetrathiomolybdate in the treatment of acute hepatitis in an animal model for Wilson disease

BACKGROUND/AIMS

Tetrathiomolybdate (TTM) is a potent copper-chelating agent that has been shown to be effective in Wilson disease patients with neurological symptoms. Here, we investigate the potential use of TTM in treating the acute hepatic copper toxicosis in Long-Evans Cinnamon (LEC) rats, an authentic model for Wilson disease.

METHODS

After the onset of acute hepatitis, LEC rats were treated once with 10 mg TTM/kg. After 1 and 4 days, parameters of liver toxicity and the subcellular distribution and binding of copper and iron were studied.

RESULTS

In 11 out of 12 rats TTM rapidly improved acute hepatitis. Hepatic copper decreased through removal from cytosolic metallothionein and lysosomal metallothionein polymers. The remaining lysosomal copper forms a metallothionein-copper-TTM complex. In an almost moribund rat, however, TTM caused severe hepatotoxicity with fatal outcome.

CONCLUSIONS

TTM is effective in treating acute hepatitis in LEC rats when applied before the animals become moribund. TTM appears to act by removing the presumable reactive copper associated to lysosomal metallothionein polymers. The remaining lysosomal copper seems to be inactivated by forming a complex with TTM. Moreover, TTM removes copper from cytosolic copper-containing metallothionein. As a consequence, metallothionein is degraded and the uptake of copper-metallothionein into the lysosomes and the formation of the metallothionein polymer associated copper is reduced.

Innervation of immune cells: Evidence for neuroimmunomodulation in the liver

Recent studies have demonstrated a pronounced influence by the autonomic nervous system on immune-mediated experimental hepatitis in the mouse. Adrenergic sympathetic neurons alleviate while capsaicin-sensitive peptidergic primary afferent neurons aggravate liver injury. This was evidenced by recording morphological and functional parameters upon chemical sympathectomy and application of beta-adrenergic agonists, and capsaicin depletion of afferents, neurokinin receptor antagonists, and application of exogenous substance P, respectively. These phenomena are most likely based on close anatomical relationships between nerve fibers and various immune cells in the liver. Modulation of autonomic nervous system functions may open novel therapeutic strategies in immune and inflammatory liver diseases.

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.

Evidence of alterations in base excision repair of oxidative DNA damage during spontaneous hepatocarcinogenesis in Long Evans Cinnamon rats

The Long-Evans Cinnamon (LEC) rat, an animal model for Wilson's disease, is an inbred mutant strain, which because of the genetic copper metabolism disorder develops hepatitis approximately 4 months after birth, followed by chronic hepatitis later in life, and eventually all of the surviving animals from liver injury and hepatitis develop spontaneous hepatocellular carcinomas. This animal model also shows that the generation of reactive oxygen species and the accumulation of oxidative damage in the liver DNA has significantly increased over the lifetime of LEC versus the wild-type Long-Evans Agouti (LEA) rats. Thus, the LEC rats having this genetically induced oxidative condition are proved to be very useful model for the study of endogenous DNA lesions and their relation to spontaneous carcinogenesis. In this study, we tested the hypothesis that differences do exist between these two rat strains in respect to their capacity to repair oxidative DNA base modification, which could explain the elevation of endogenous oxidative damage in the LEC rat liver DNA. We found that both the activity and expression at the protein and RNA levels of major DNA glycosylases, endonuclease III and 8-oxoguanine DNA-glycosylase, which initiate the excision and repair of oxidized bases, were significantly altered during the acute (16-18 weeks) and early chronic (24 weeks) phases of hepatitis. Enzyme levels were restored in the later period of chronic hepatitis (week 40) in the LEC rat liver as compared with the age-matched LEA rats. This early reduction in the capacity to repair oxidative DNA base damage could have contributed to the accumulation of mutagenic adducts in liver DNA. These findings show for the first time in an animal model that acute hepatitis impairs the repair of oxidative DNA base damage and strongly suggest that the repair of endogenous DNA adducts plays a critical role in the development of spontaneous hepatocellular carcinoma in LEC rats.

Antisense oligonucleotide inhibition of Bcl-xL and Bid expression in liver regulates responses in a mouse model of Fas-induced fulminant hepatitis

Activation of the cell-surface receptor Fas can lead to apoptosis in parenchymal cells in the liver, and if severe enough, result in fulminant hepatic failure and animal death. In the present study, we have examined the roles played by the Bcl-2 family members Bcl-xL and Bid in regulating this response. To do this, we have developed chemically modified 2'-O-(2-methoxy) ethyl antisense inhibitors of both Bid and Bcl-xL expression. In Balb/c mice, dosing with these antisense oligonucleotides reduced expression of the targeted mRNA by greater than 80% in the liver. This reduction was highly dependent upon oligonucleotide sequence and oligonucleotide dose. Reduction of Bcl-xL expression resulted in a potentiation of Fas-mediated apoptosis in liver and significant increase of the lethality of Fas-mediated fulminant hepatitis (p < 0.0001). In contrast, reduction of Bid expression protected the animals against Fas-mediated fulminant hepatitis and death (p < 0.0001). Simultaneous dosing of mice with Bcl-xL and Bid-targeting antisense oligonucleotides resulted in an inhibition of expression of both targeted proteins and protection of the animals from Fas-mediated apoptosis. These results demonstrate, for the first time, the role of Bcl-xL in regulating responses to proapoptotic Fas signaling in mouse liver. In addition, this is the first reported example demonstrating the ability of antisense inhibitors to reduce expression of multiple proteins in animals by simultaneous dosing.

Mice lacking TNFalpha receptors 1 and 2 are resistant to death and fulminant liver injury induced by agonistic anti-Fas antibody

The liver is particularly susceptible to Fas-mediated cytotoxicity. Mice given an adequate parenteral dose of agonistic anti-Fas antibody (aFas) or of FasL are known to develop a devastating liver injury and to die in a few hours. The present work shows that mice lacking TNFR1 and TNFR2 (R(-)) both survive a single dose of aFas, otherwise rapidly lethal, and develop a mild form of hepatic damage, compared to the much more severe liver injury that in a few hours strikes wild-type mice (R(+)), eventually involving increased activity of proteases of different families (caspase 3-, 8-, and 9-like, calpains, cathepsin B). Neither the overall tissue levels of Fas and FasL nor Fas expression at the hepatocyte surface are altered in the liver of R(-) animals. The DNA-binding activity of the NF-kappaB transcription factor is enhanced after aFas treatment, but much more markedly in R(-) than in R(+) mice. Bcl2, while unchanged in untreated animals, is markedly upregulated in R(-) but not in R(+) mice challenged with aFas. The requirement of a normal TNFR1/TNFR2 phenotype for full deployment of the general and liver-specific aFas toxicity in mice most likely implies that treatment with aFas in some way results in activation of the TNFalpha-TNFRs system and that this activation synergizes with Fas-mediated signals in causing the fulminant liver injury and the animal death. The precise cellular and molecular details underlying this interplay between Fas- and TNFRs-mediated signaling systems in the general and liver-specific aFas toxicity largely remain to be clarified.

Gene expression in the liver of Long-Evans cinnamon rats during the development of hepatitis

The Long-Evans cinnamon (LEC) rat, an authentic model for Wilson disease, is characterized by a mutation in the Atp7b gene leading to a defective copper excretion and, as a consequence, to an accumulation of the metal in the liver and copper-associated hepatotoxicity. In the present communication expression profiles of genes in the liver from wild-type Long-Evans agouti (LEA) and LEC rats at different stages of copper accumulation and liver disease were investigated. Disease states were defined according to serum aspartate aminotransferase activity and bilirubin levels in serum and from histopathology of the liver. Gene expression was determined with the Affymetrix RTU34 oligonucleotide array covering 1031 genes. Compared to the LEA rat, the nondiseased LEC rat with already increased hepatic copper level showed an enhanced expression of genes, particularly related to oxidative stress and DNA damage. During the progression of the liver disease, in particular genes related to oxidative stress, DNA damage, apoptosis and inflammation with acute-phase reaction were upregulated.

Spontaneous oxidative stress and liver tumors in mice lacking methionine adenosyltransferase 1A

In mammals, methionine metabolism occurs mainly in the liver via methionine adenosyltransferase-catalyzed conversion to S-adenosylmethionine. Of the two genes that encode methionine adenosyltransferase(MAT1Aand MAT2A), MAT1A is mainly expressed in adult liver whereas MAT2A is expressed in all extrahepatic tissues. Mice lacking MAT1A have reduced hepatic S-adenosylmethionine content and hyperplasia and spontaneously develop nonalcoholic steatohepatitis. In this study, we examined whether chronic hepatic S-adenosylmethionine deficiency generates oxidative stress and predisposes to injury and malignant transformation. Differential gene expression in MAT1A knockout mice was analyzed following the criteria of the Gene Ontology Consortium. Susceptibility of MAT1A knockout mice to CCl4-induced hepatotoxicity and malignant transformation was determined in 3- and 18-month-old mice, respectively. Analysis of gene expression profiles revealed an abnormal expression of genes involved in the metabolism of lipids and carbohydrates in MAT1A knockout mice, a situation that is reminiscent of that found in diabetes, obesity, and other conditions associated with nonalcoholic steatohepatitis. This aberrant expression of metabolic genes in the knockout mice was associated with hyperglycemia, increased hepatic CYP2E1 and UCP2 expression and triglyceride levels, and reduced hepatic glutathione content. The knockout animals have increased lipid peroxidation and enhanced sensitivity to CCl4-induced liver damage, which was largely due to increased CYP2E1 expression because diallyl sulfide, an inhibitor of CYP2E1, prevented CCl4-induced liver injury. Hepatocellular carcinoma developed in more than half of the knockout mice by 18 months of age. Taken together, our findings define a critical role for S-adenosylmethionine in maintaining normal hepatic function and tumorigenesis of the liver.

Time course profile and cell-type-specific production of monokine induced by interferon-gamma in Concanavalin A-induced hepatic injury in mice: comparative study with interferon-inducible protein-10

BACKGROUND

We have previously shown that interferon-inducible protein-10 (IP-10), a chemokine for activated lymphocytes, was specifically induced in the liver of Concanavalin A (Con A)-treated mice. The aim of this study was to investigate the time course profile and cell-type-specific hepatic production of monokine induced by interferon-gamma (MIG), a chemokine which shares its receptor and most of its activity with IP-10, in Con A-treated mice and to compare them with those of IP-10.

METHODS

Hepatic mRNA expression of MIG and IP-10 was studied by means of Northern blot analysis and in situ hybridization in Con A-treated mice. The levels of MIG and IP-10 in the serum and culture supernatants of murine hepatoma-, hepatic sinusoidal endothelial cell-, hepatic stellate cell- and macrophage-derived cell lines were determined by means of specific enzyme-linked immunosorbent assays.

RESULTS

The serum level of MIG slowly reached a maximum at 12 h after Con A injection and remained elevated for a long time, whereas that of IP-10 reached a maximum at 3 h and declined quickly, a finding supported by Northern blot analysis. Using in situ hybridization, the mRNA of MIG as well as IP-10 was found to be expressed in hepatocytes and hepatic non-parenchymal cells. Similar to IP-10, MIG was produced by hepatoma-, hepatic sinusoidal endothelial cell-, hepatic stellate cell- and macrophage-derived cell lines in vitro.

CONCLUSIONS

Although both MIG and IP-10 were produced by hepatocytes and hepatic non-parenchymal cells in Con A-treated mice, the time course profile of MIG was distinguishable from that of IP-10. The fact that hepatic MIG and IP-10 were produced sequentially in this hepatitis model may suggest that a non-redundant role is played by these two chemokines in the process of hepatic necro-inflammation.