Hepatic fibrosis. Pathogenesis and principles of therapy

Loss of MMP 13 attenuates murine hepatic injury and fibrosis during cholestasis

Cholestasis occurs in a variety of clinical settings and often results in liver injury and secondary biliary fibrosis. Several matrix metalloproteinases (MMPs) are upregulated in the liver during cholestasis. The function of the major interstitial collagenase, MMP-13, in the initial phase of liver fibrosis is unknown. The aim of this study was to evaluate the role of MMP-13 during the development of cholestasis-induced liver fibrosis by comparing wild-type and MMP-13-deficient mice. Cholestasis was induced by bile duct ligation (BDL) for 5 days or 3 weeks. Activation and proliferation of hepatic stellate cells (HSCs) were detected by immunohistochemistry. Expression of MMP-13 mRNA increased significantly in BDL livers of WT mice. After BDL for 3 weeks liver fibrosis was suppressed in MMP-13-deficient mice versus WT animals. Activation and proliferation of HSCs were also suppressed in livers of MMP-13-deficient mice after BDL. To clarify the mechanism of this suppression, samples from 5-day BDL mice were used for evaluation of liver injury. Compared with those in WT animals, serum ALT and the number of hepatic neutrophils were reduced in MMP-13-deficient mice. Increased expression of the mRNA of inflammatory mediators such as tumor necrosis factor-alpha (TNF-alpha) was significantly suppressed in livers of MMP-13-deficient mice. Upregulation of fibrogenic markers, for example, transforming growth factor beta1 (TGF-beta1), was also significantly suppressed in livers of MMP-13-deficient mice versus in WT mice. In conclusion, distinct from the known function of interstitial collagenase to reduce liver fibrosis by degrading the extracellular matrix, MMP-13 contributes to accelerating fibrogenesis in cholestatic livers by mediating the initial inflammation of the liver.

Roles of activin A and hepatocellular apoptosis in the anti-liver fibrosis process induced by Ginkgo biloba extract in rats

AIM: To investigate the effects of Ginkgo biloba extract (GBE) on CCl₄-induced liver fibrosis as well as the underlying mechanisms.

METHODS: Thirty adult male Sprague Dawley rats were randomized into 3 groups: control group (n = 10), model group (n = 10) and treatment group (n = 10). Except the rats in the control group, the others were intraperitoneally injected with 500 mL/L CCl₄ (1 mL/kg) to induce liver cirrhosis (twice a week, for 8 weeks). Moreover, the rats in treatment group were intragastrically administered with GBE (0.4 g/kg) for 8 weeks. At the end of the 8^th week, all the rats were sacrificed. Blood samples were collected for the determination of biochemical indicators. Tissue samples were used for histopathological examinations. The expression of activin A was determined by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). Hepatocellular apoptosis was determined by the method of terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) method.

RESULTS: The grade of liver fibrosis in treatment group was lower than that in the model group (P < 0.05). The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and albumin (ALB) in treatment group were significantly improved as compared with those in the model group (ALT: 2806.9 ±576.1 nkat/L vs 4452.9 ± 709.5 nkat/L; AST: 5314.2 ± 1042 nkat/L vs 15 743.4 ± 625.8 nkat/L; ALB: 31.0 ± 2.1 g/L vs 21.7 ± 1.8 g/L; all P < 0.05). GBE treatment markedly reduced mRNA and protein levels of activin A (mRNA: 0.42 ± 0.09 vs 0.78 ± 0.15; protein: 4.2 ± 0.8 vs 11.4 ± 1.2; both P < 0.01). In comparison with that in the model group, the apoptosis index was decreased in treatment groups (7.56 ± 3.36 vs 16.06 ± 8.84, P < 0.01).

CONCLUSION: GBE can markedly attenuate the degrees of hepatic fibrosis, and the mechanism may be correlated with the expression of activin A and hepatocellular apoptosis.

Hepatocyte growth factor attenuates liver fibrosis induced by bile duct ligation

Hepatic fibrosis is a common outcome of a variety of chronic liver diseases. Here we evaluated the therapeutic efficacy of hepatocyte growth factor (HGF) on liver fibrosis induced by bile duct ligation (BDL) and investigated potential mechanisms. Mice underwent BDL, followed by intravenous injections of naked HGF expression plasmid or control vector. HGF gene therapy markedly ameliorated hepatic fibrotic lesions, as demonstrated by reduced alpha-smooth muscle actin (alphaSMA) expression, attenuated deposition of type I and type III collagen, and normalized total hydroxyproline content. HGF also suppressed transforming growth factor-beta1 (TGF-beta1) expression. Interestingly, colocalization of alphaSMA and cytokeratin-19 in bile duct epithelium was observed, suggesting the possibility of biliary epithelial to myofibroblast transition after BDL. Cells that were still positive for cytokeratin-19 but actively producing type I collagen were found in the biliary epithelia and periductal region. Laminin staining revealed an impaired basement membrane of the bile duct epithelium in diseased liver. These lesions were largely prevented by HGF administration. In vitro, treatment of human biliary epithelial cells with TGF-beta1 induced alphaSMA and fibronectin expression and suppressed cytokeratin-19. HGF abolished the phenotypic conversion of biliary epithelial cells induced by TGF-beta1. These results suggest that HGF ameliorates hepatic biliary fibrosis in part by blocking bile duct epithelial to mesenchymal transition.

[Therapeutic effect of Bushen Rougan Recipe on hepatic fibrosis in rats]

OBJECTIVE

To study the therapeutic effect of Bushen Rougan Recipe (BSRGR) on hepatic fibrosis in rats.

METHODS

Forty male Wistar rats were randomly divided into normal control group (n=10), model group (n=15), and BSRGR-treated group (n=15). Rats in the model and BSRGR-treated groups were administered intraperitoneally with 0.5% dimethylnitrosamine (DMN), 10 mg.kg(-1).d(-1), successive 3 days per week for 4 weeks to induce hepatic fibrosis. Then rats in the above 2 groups were given normal saline and BSRGR (10 ml.kg(-1).d(-1), ig) for another 4 weeks, respectively. Rats in the 3 groups were all executed at the end of the 8th week. The serum total bilirubin (TBIL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (A) and globulin (G) were determined and the serum hyaluronic acid (HA), laminin (LN) and collagen IV (IV-C) were measured.

RESULTS

The rat model of liver fibrosis was successfully induced by DMN. It was found that the serum TBIL, AST and ALT and the liver fibrosis marks were declined in BSRGR-treated group as compared with those in the model group (P<0.01). The content of total serum protein and the A/G in BSRGR-treated group were both increased as compared with those in the model group (P<0.05).

CONCLUSION

BSRGR can be used to treat hepatic fibrosis in rats.

Therapeutic effect of interleukin-10 on CCl4-induced hepatic fibrosis in rats

AIM: To study the therapeutic effect of exogenous interleukin-10 on CCl₄-induced hepatic fibrosis in rats and its possible mechanisms.

METHODS: Fourty-seven SD rats were randomly divided into control group (group N) and CCl₄-induced hepatic fibrosis model group (group C). After CCl₄ was given for 9 wk, the model group was divided into three groups. Rats in group M were put to death immediately, rats in group T were treated with IL-10 for another three wk and then put to death, rats in group R recovered after three weeks and were then killed. The degree of hepatic fibrosis was measured by HE staining and histological activity index (HAI). Histological activity index (HAI), change of collagen types I and III were measured by Picrosirius staining. The expression of TNF-α, MMP-2 and TIMP-1 in liver tissue was measured by S-P immunohistochemistry.

RESULTS: CCl₄- induced experimental rat hepatic fibrosis model was established successfully. The degree of hepatic fibrosis was markedly lower in group T than in groups M and R, and there was no difference between the two groups. The expression of collagen types I and III was significantly suppressed in group T and was slightly suppressed in groups M and R. The positive levels of TNF-α, MMP-2 and TIMP-1 in group M increased significantly compared to those in group N (P < 0.01). The positive signals decreased significantly in groups T and R (P < 0.01), but positive score was significantly lower in group T than in group R (P < 0.01).

CONCLUSION: Exogenous IL-10 can reverse CCl₄-induced hepatic fibrosis in rats. IL-10 may exert its reversible effects on hepatic fibrosis by blocking CCl₄-induced inflammation, inhibiting expression of MMP-2 and TIMP-1 and promoting resolution of collagen types I and III.

Protection against D-Galactosamine-Induced Acute Liver Injury by Oral Administration of Extracts from Lentinus edodes Mycelia

The development of oral medications to help prevent liver injury is desirable, and some mushrooms contain chemicals that show promise as such a treatment. Here, we tested whether a hot-water extract (L.E.M.) of the cultured mycelia of an edible mushroom, Lentinus edodes, could protect primary cultured hepatocytes from D-galactosamine (GalN)-induced injury. GalN induced cell death in the hepatocytes, and this effect was completely suppressed by the addition of 0.5 mg/ml L.E.M. Polyphenolic compounds contained in the L.E.M. seemed to be responsible for the protective effect. We next examined the protective effect of L.E.M. in a GalN-induced liver injury model in rats. In rats that had been treated with L.E.M. given orally or intraperitoneally, GalN caused less leakage of aspartate aminotransferase and alanine aminotransferase, markers for liver injury, and a lower decrease in serum protein content, than in non-L.E.M.-treated rats. Histological analysis of the liver also showed a protective effect of L.E.M. Our findings indicate that L.E.M. administration is a promising treatment for protecting the liver from acute injury.

Antifibrotic agents for liver disease

Complications from chronic hepatitis C (HCV) and recurrent HCV post-transplant are responsible for significant morbidity and mortality in the United States and Europe. Current antiviral therapies are at best, effective in up to 50% of patients in the pre-transplant setting, and in the post-transplant setting are associated with more limited efficacy and increased toxicity. With this reduced efficacy of antiviral strategies in the post-transplant setting, new approaches are urgently needed. Substantial progress has been made in understanding the pathogenesis of hepatic fibrosis over the last 20 years, which has yielded potential new therapeutic targets. The prospect of antifibrotic therapies is nearing reality in order to reduce progression to cirrhosis, thereby reducing morbidity, mortality and the need for re-transplantation. Current and evolving approaches primarily target the activated hepatic stellate cells, which are the main source of extracellular matrix, along with related fibrogenic cell types. Key issues yet to be clarified include the optimal duration of antifibrotic therapies, endpoints of clinical trials, indications in clinical practice and whether combination therapies might yield synergistic activity.

A new model of hepatic fibrosis induced by intra-arterial injection of iodized oil and pingyangmycin emulsions

AIM: To investigate the feasibility of setting up a hepatic fibrosis model by intra-arterial injection of emulsions of iodized oil and pingyangmycin.

METHODS: Twenty-four Japanese big-ear rabbits were divided into sham-operation, experiment A and B group according to the doses of emulsions of iodized oil and pingyangmycin (1.2 and 2.0 mg for A and B, respectively) injected into the hepatic artery. The live specimens were obtained 1, 2, 4, 6, 10, and 14 wk after injection. The histological changes were determined by HE staining, and the contents of platelet derived growth factor-B (PDGF-B) were detected by immunohistochemical staining.

RESULTS: Six weeks after injection, typical features of fibrosis appeared in all the liver tissues of group A and B, and the pseudolobules formed in some tissues. In group B, sclerosis with a diameter of 1.0 cm was found in one of the four rabbits at 10th week under light microscope. The contents of PDGF-B were significantly increased in A and B group as compared with those in sham-operation group 1, 2, 4, and 6 wk after injection (integral optical density: 118714±14941, 154344±25102 vs 42745±871, P <0.01; 130399±11690, 164855±15486 vs 44052±1043, P <0.01; 116594±21230, 147099±20317 vs 41081±769, P <0.01; 101732±8794, 124177±20429 vs 46366±975, P <0.01).

CONCLUSION: The model of hepatic fibrosis can be established successfully by injection of iodized oil and pingyangmycin emulsions into the hepatic artery. PDGF-B plays an important role in the progress of fibrosis as a promoter.

Lack of therapeutic improvement of liver fibrosis in rats by dexamethasone in spite of ascites amelioration

Pathophysiology of liver fibrosis (LF) includes hepatic parenchymal cell destruction and connective tissue formation. Although dexamethasone has been used in the liver diseases, there is controversy over the beneficial effects of dexamethasone on LF. Previous studies showed that CCAAT/enhancer binding protein-beta (C/EBPbeta) activation contributes to hepatocyte regeneration and dissolution of fibrosis and that dexamethasone activates C/EBPbeta whereas C/EBPbeta-mediated gene induction by dexamethasone is antagonized by a corepressor. The present study investigated the possible therapeutic effect of dexamethasone for the treatment of LF in rats. We injected rats with multiple doses of dimethylnitrosamine (DMN) for 4 weeks and then used the LF rats to determine whether dexamethasone treatment therapeutically improved liver functions and resolved fibers accumulated in the liver. Dexamethasone (100 microg/kg, po, three times per week for 4 weeks) failed to restore the body weight gain and liver weight decreased by LF. The body weight gain reduced during LF was further decreased by dexamethasone treatment. Animals were subjected to blood biochemical, liver histopathological and immunochemical analyses. Although dexamethasone treatment significantly reduced ascites in LF rats, the plasma albumin and total protein levels decreased in fibrotic rats were not restored. Impaired liver functions during LF including elevated plasma aminotransferases and bilirubin levels along with GSTA2 repression were not recovered by dexamethasone. Dexamethasone failed to decrease the fibrosis score and to eliminate the extracellular matrix and alpha-smooth muscle actin accumulated in the fibrotic liver. The results of the present study showed that dexamethasone ameliorated ascites in LF rats but failed to improve the liver functions and fiber accumulation, and that the possible beneficial effect of dexamethasone might result from anti-inflammatory effect but not from liver improvement.

Association of myeloperoxidase promotor polymorphism with cirrhosis in patients with hereditary hemochromatosis

BACKGROUND/AIMS

Hereditary hemochromatosis (HHC) is a disorder of iron metabolism with variable penetrance. Oxidative stress plays a central role in the progression to cirrhosis. Several enzymes involved in the production or degradation of reactive oxidants, like myeloperoxidase (MPO) and heme oxygenase (HO)-1 are influenced by promotor polymorphisms. This study assessed the impact of polymorphisms of the MPO (-463G/A) and the HO-1 promotors of Vienna (GT)n on the evolution of cirrhosis in patients with HHC.

METHODS

One-hundred and fifty-eight C282Y homozygotes without cofactors for fibrosis progression (119 males; mean age: 51.0+/-13.3) were studied. All patients underwent liver biopsy. Hepatic iron content was measured by atom absorption spectrophotometry. MPO polymorphism was assessed by RFLP analysis; HO-1 microsatellite polymorphism by a laser-based semi-automated DNA sequencer.

RESULTS

The MPO genotypes GG, GA, and AA were found in 102 (64.6%), 45 and 11 patients, respectively. The GG-genotype was more common in patients with cirrhosis than in those without (78.7 vs. 55.7%, P=0.003). The distribution of HO-1 genotypes was not different. Logistic regression analysis revealed MPO genotype-GG, serum ferritin, age and male sex as independent predictors for cirrhosis.

CONCLUSIONS

MPO genotype GG is associated with cirrhosis in patients with hereditary hemochromatosis.

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Imatinib mesylate (STI-571) attenuates liver fibrosis development in rats

It is widely recognized that activated hepatic stellate cells (HSC) play a pivotal role in development of liver fibrosis. A platelet-derived growth factor (PDGF) is the most potent mitogen for HSC. The aim of this study was to examine the effect of imatinib mesylate (STI-571, Gleevec), a clinically used PDGF receptor (PDGFR) tyrosine kinase inhibitor, on development of experimental liver fibrosis. The rat model of pig serum-induced hepatic fibrosis was used to assess the effect of daily oral administration of STI-571 on the indexes of fibrosis. STI-571 markedly attenuated development of liver fibrosis and hepatic hydroxyproline and serum fibrosis markers. The number of alpha-smooth muscle actin-positive cells and mRNA expression of alpha2-(I)-procollagen, tissue inhibitor of metalloproteinases-1, and transforming growth factor-beta were also significantly suppressed by STI-571. Our in vitro study showed that STI-571 markedly attenuated PDGF-BB-induced proliferation and migration and alpha-SMA and alpha2-(I)-procollagen mRNA of activated HSC in a dose-dependent manner. STI-571 also significantly attenuated PDGF-BB-induced phosphorylation of PDGFR-beta, MEK1/2, and Akt in activated HSC. Because STI-571 is widely used in clinical practice, it may provide an effective new strategy for antifibrosis therapy.

Hepatoprotective effect of extracts from Lentinus edodes mycelia on dimethylnitrosamine-induced liver injury

Mycelia of the edible mushroom Lentinus edodes (shiitake) were cultivated in a solid medium, and two fractions were obtained by hot-water extraction (L.E.M.) and then ethanol extraction followed by Sephadex LH-20 column chromatography (ESMe). The L.E.M. and ESMe were then examined for their hepatoprotective effect on dimethylnitrosamine-injured mice. Both fractions decreased the blood aspartate aminotransferase and alanine aminotransferase levels, partially inhibited the overaccumulation of collagen fibrils, and suppressed the overexpression of genes for alpha-smooth muscle actin and/or heat-shock protein 47 in the mice. Both fractions also inhibited the morphologic change and proliferation of isolated rat hepatic stellate cells (HSCs), which play a central role in liver fibrosis, in a dose-dependent manner and without cytotoxicity. The direct interaction between the extracts and HSCs appears to be important for the hepatoprotective activity. Polyphenols contained in both fractions are considered to be potential candidates for expressing the hepatoprotective effects. The finding of antifibrotic activity in extracts from an edible mushroom is expected to be helpful in the development of hepatoprotective agents with few side effects.

Effects of total glucosides of peony on immunological hepatic fibrosis in rats

AIM

To study the effects of total glucosides of peony (TGP) on immunological hepatic fibrosis induced by human albumin in rats.

METHODS

Sixty adult male Sprague-Dawley rats were randomly divided into: Normal group, model group, TGP (60 and 120 mg/kg) treatment groups and colchicines (0.1 mg/kg) treatment group. On the day before the rats were killed, those in TGP or colchicine groups received TGP or colchicine as above from the first day of tail vein injection of human albumin. The rats in normal and model groups were only administered with the same volume of vehicle. At the end of the 16th wk, rats in each group were killed. Blood and tissue specimens were taken. Levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), nitric oxide (NO), content of malondialdehyde (MDA), activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-px), were measured by biochemical methods. Serum procollagen type III (PC III) and laminin (LN) were determined by radioimmunoassay. Liver collagen level was determined by measuring hydroxyproline content in fresh liver samples. Hepatic tissue sections were stained with hematoxylin-eosin and examined under a light microscope.

RESULTS

Histological results showed that TGP improved the human albumin-induced alterations in the liver structure, alleviated lobular necrosis and significantly lowered collagen content. The antifibrotic effect of TGP was also confirmed by decreased serum content of LN and PCIII in TGP-treated group. Moreover, the treatment with TGP effectively reduced the hydroxyproline content in liver homogenates. However, the level of ALT and AST increased in fibrotic rat but had no significance compared with normal control, whereas the ratio of A/G decreased without significance. TGP had no effect on level of ALT, AST and the ratio of A/G. Furthermore, TGP treatment significantly blocked the increase in MDA and NO, associated with a partial elevation in liver total antioxidant capacity including SOD and GSH-px.

CONCLUSION

TGP has beneficial effects on hepatic fibrosis in rats by inhibition of collagen synthesis and decreasing oxidative stress.

Liver fibrosis

Liver fibrosis is the excessive accumulation of extracellular matrix proteins including collagen that occurs in most types of chronic liver diseases. Advanced liver fibrosis results in cirrhosis, liver failure, and portal hypertension and often requires liver transplantation. Our knowledge of the cellular and molecular mechanisms of liver fibrosis has greatly advanced. Activated hepatic stellate cells, portal fibroblasts, and myofibroblasts of bone marrow origin have been identified as major collagen-producing cells in the injured liver. These cells are activated by fibrogenic cytokines such as TGF-beta1, angiotensin II, and leptin. Reversibility of advanced liver fibrosis in patients has been recently documented, which has stimulated researchers to develop antifibrotic drugs. Emerging antifibrotic therapies are aimed at inhibiting the accumulation of fibrogenic cells and/or preventing the deposition of extracellular matrix proteins. Although many therapeutic interventions are effective in experimental models of liver fibrosis, their efficacy and safety in humans is unknown. This review summarizes recent progress in the study of the pathogenesis and diagnosis of liver fibrosis and discusses current antifibrotic strategies.

Liver fibrosis

Liver fibrosis is the excessive accumulation of extracellular matrix proteins including collagen that occurs in most types of chronic liver diseases. Advanced liver fibrosis results in cirrhosis, liver failure, and portal hypertension and often requires liver transplantation. Our knowledge of the cellular and molecular mechanisms of liver fibrosis has greatly advanced. Activated hepatic stellate cells, portal fibroblasts, and myofibroblasts of bone marrow origin have been identified as major collagen-producing cells in the injured liver. These cells are activated by fibrogenic cytokines such as TGF-beta1, angiotensin II, and leptin. Reversibility of advanced liver fibrosis in patients has been recently documented, which has stimulated researchers to develop antifibrotic drugs. Emerging antifibrotic therapies are aimed at inhibiting the accumulation of fibrogenic cells and/or preventing the deposition of extracellular matrix proteins. Although many therapeutic interventions are effective in experimental models of liver fibrosis, their efficacy and safety in humans is unknown. This review summarizes recent progress in the study of the pathogenesis and diagnosis of liver fibrosis and discusses current antifibrotic strategies.

Liver fibrosis

Liver fibrosis is the excessive accumulation of extracellular matrix proteins including collagen that occurs in most types of chronic liver diseases. Advanced liver fibrosis results in cirrhosis, liver failure, and portal hypertension and often requires liver transplantation. Our knowledge of the cellular and molecular mechanisms of liver fibrosis has greatly advanced. Activated hepatic stellate cells, portal fibroblasts, and myofibroblasts of bone marrow origin have been identified as major collagen-producing cells in the injured liver. These cells are activated by fibrogenic cytokines such as TGF-beta1, angiotensin II, and leptin. Reversibility of advanced liver fibrosis in patients has been recently documented, which has stimulated researchers to develop antifibrotic drugs. Emerging antifibrotic therapies are aimed at inhibiting the accumulation of fibrogenic cells and/or preventing the deposition of extracellular matrix proteins. Although many therapeutic interventions are effective in experimental models of liver fibrosis, their efficacy and safety in humans is unknown. This review summarizes recent progress in the study of the pathogenesis and diagnosis of liver fibrosis and discusses current antifibrotic strategies.

Liver fibrosis

Liver fibrosis is the excessive accumulation of extracellular matrix proteins including collagen that occurs in most types of chronic liver diseases. Advanced liver fibrosis results in cirrhosis, liver failure, and portal hypertension and often requires liver transplantation. Our knowledge of the cellular and molecular mechanisms of liver fibrosis has greatly advanced. Activated hepatic stellate cells, portal fibroblasts, and myofibroblasts of bone marrow origin have been identified as major collagen-producing cells in the injured liver. These cells are activated by fibrogenic cytokines such as TGF-beta1, angiotensin II, and leptin. Reversibility of advanced liver fibrosis in patients has been recently documented, which has stimulated researchers to develop antifibrotic drugs. Emerging antifibrotic therapies are aimed at inhibiting the accumulation of fibrogenic cells and/or preventing the deposition of extracellular matrix proteins. Although many therapeutic interventions are effective in experimental models of liver fibrosis, their efficacy and safety in humans is unknown. This review summarizes recent progress in the study of the pathogenesis and diagnosis of liver fibrosis and discusses current antifibrotic strategies.

Effect of S-adenosyl-L-methionine on the activation, proliferation and contraction of hepatic stellate cells

Inhibition of hepatic stellate cell activation is an important clinical aspect for the control of liver inflammation, fibrosis and cirrhosis. S-adenosyl-L-methionine (SAM), an intermediate product of L-methionine metabolism, is a precursor of glutathione and an endogenous methyl donor. Although the hepato-protective action of SAM has been reported in several animal models, the effect of SAM on the function of hepatic stellate cells has not been elucidated. Using a primary-culture model of hepatic stellate cells, we found that SAM blunts the activation process as indicated by the suppression of expression of collagen alpha1(I) and smooth muscle alpha-actin. SAM also hampers the DNA synthesis of hepatic stellate cells stimulated with a dimer of platelet-derived growth factor-B via the inhibition of phosphorylation of PDGF receptor-beta and down-stream signaling pathways. SAM additionally inhibits the contraction of hepatic stellate cells by disturbing the formation of F-actin stress fibers and phosphorylated myosin light chains. Thus, SAM regulates the activation of hepatic stellate cells and may clinically contribute to therapy targeted at human liver fibrosis.

In vivo effects of Chinese herbal recipe, Danshaohuaxian, on apoptosis and proliferation of hepatic stellate cells in hepatic fibrotic rats

AIM

To investigate the effects of Danshaohuaxian (DSHX), a Chinese herbal recipe, on the apoptosis and cell cycles of hepatic stellate cells (HSCs) in rat hepatic fibrosis and its possible mechanisms.

METHODS

Seventy-six male Wistar rats were randomly divided into normal control group, hepatic fibrosis group, non-DSHX-treated group and DSHX-treated group. Except for the normal control group, rat hepatic fibrotic models were induced by subcutaneous injection of carbon tetrachloride (CCl4), drinking alcohol, giving diet of hyperlipid and hypoprotein for 8 wk. When the hepatic fibrotic models were produced, 12 rats of hepatic fibrosis group (15 rats survived, others died during the 8 wk) were sacrificed to collect blood and livers. HSCs were isolated from the other 3 rats to detect the apoptotic index (AI) and cell cycles by flow cytometry. DSHX was then given to the DSHX-treated group (1.0 g/kg, PO, daily) for 8 wk. At the same time, normal control group and non-DSHX-treated group were given normal saline for 8 wk. At end of the experiment, some rats in these three groups were sacrificed to collect blood and livers, the other rats were used for HSC isolation to detect the apoptotic index (AI) and cell cycles. Then the liver index, serum hyaluronic acid (HA) and alanine aminotransferase (ALT), degree of hepatic fibrosis, urinary excretion of hydroxyproline (Hyp) and expression of collagen types I and III (COL I and III) in these four groups were detected respectively.

RESULTS

Compared with the indexes of the hepatic fibrosis group and non-DSHX-treated group, the DSHX-treated group revealed a liver index of (0.0267+/-0.0017 vs 0.0423+/-0.0044, 0.0295+/-0.0019, P<0.05), levels of serum HA (200.78+/-31.71 vs 316.17+/-78.48, 300.86+/-72.73, P<0.05) and ALT (93.13+/-5.79 vs 174.5+/-6.02, 104.75+/-6.54, P<0.01), and stage of hepatic fibrosis (1.30 vs 4.25, 2.60, P<0.01) all reduced. The urinary excretion of Hyp increased (541.09+/-73.39 vs 62.00+/-6.40, 182.44+/-30.83, P<0.01), the COL I and III expression decreased (COL I: 1.07+/-0.96 vs 4.18+/-2.26, 3.22+/-1.44, P<0.01; COL III: 1.09+/-0.58 vs 3.04+/-0.62, 2.23+/-0.58, P<0.01), the HSCs apoptotic index of HSCs (7.81+/-0.47 vs 1.63+/-0.25, 1.78+/-0.4, P<0.05) and the ratio of G0-G1 phase cells increased (94.30+/-1.33 vs 62.27+/-17.96, 50.53+/-2.25, P<0.05). The ratios of S-phase cells (3.11+/-1.27 vs 9.83+/-1.81, 11.87+/-1.9, P<0.05) and G2-M phase cells (2.58+/-0.73 vs 23.26+/-10.95, 13.60+/-1.15, P<0.01) declined.

CONCLUSION

DSHX capsule shows certain therapeutic effects on hepatic fibrosis in rats and inhibits abnormal deposition of COL I and III in rat livers by promoting the apoptosis of HSCs and preventing their proliferation.

Regulation of PDGF and its receptors in fibrotic diseases

Platelet-derived growth factor (PDGF) isoforms play a major role in stimulating the replication, survival, and migration of myofibroblasts during the pathogenesis of fibrotic diseases. During fibrogenesis, PDGF is secreted by a variety of cell types as a response to injury, and many pro-inflammatory cytokines mediate their mitogenic effects via the autocrine release of PDGF. PDGF action is determined by the relative expression of PDGF alpha-receptors (PDGFRalpha) and beta-receptors (PDGFRbeta) on the surface of myofibroblasts. These receptors are induced during fibrogenesis, thereby amplifying biological responses to PDGF isoforms. PDGF action is also modulated by extracellular binding proteins and matrix molecules. This review summarizes the literature on the role of PDGF and its receptors in the development of fibrosis in a variety of organ systems, including lung, liver, kidney, and skin.

Capsule oxymatrine in treatment of hepatic fibrosis due to chronic viral hepatitis: A randomized, double blind, placebo-controlled, multicenter clinical study

AIM: To evaluate the efficacy and safety of oxymatrine capsule in treatment of hepatic fibrosis in patients with chronic viral hepatitis.

METHODS: It was a randomized, double blind, placebo-controlled, multicenter clinical study. One hundred and forty-four patients were divided into oxymatrine capsule group(group A) and placebo group (group B).The course was 52 wk. Patients were visited once every 12 wk and the last visit was at 12 wk after cessation of the treatment. All patients had liver biopsy before treatment. part of them had a second biopsy at the end of therapy. Clinical symptoms, liver function test, serum markers of hepatic fibrosis were tested. Ultrasound evaluation was performed before, during and at the end of therapy.

RESULTS: One hundred and forty-four patients enrolled in the study. Of them 132 patients completed the study according to the protocol,49 patients had liver biopsy twice (25 patients in group A and 24 in group B). At the end of therapy, significant improvements in hepatic fibrosis and inflammatory activity based on Semi-quantitative scoring system (SSS) were achieved in group A. The total effective rate of the treatment was 48.00%, much higher than that of 4.17% in group B (P < 0.05). Significant improvement in serum markers of hepatic fibrosis such as hyaluronic acid (HA) and type III procollagenic peptide (P III P) in group A was seen (P < 0.05). The total effective rate of serum markers at the end of therapy in group A was 68.19%, much higher than that of 34.85% in group B (P < 0.05). The total effective rate of noninvasive markers at the end of therapy in group A was 66.67%, much higher than that of 30.30% in group B (P < 0.05). The rate of adverse events was similar in two groups.

CONCLUSION: Oxymatrine capsule is effective and safe in treatment of hepatic fibrosis due to chronic viral hepatitis.

Effects of platelet-derived growth factor and interleukin-10 on Fas/Fas-ligand and Bcl-2/Bax mRNA expression in rat hepatic stellate cells in vitro

AIM: To investigate the effects of platelet-derived growth factor (PDGF) and interleukin-10 (IL-10) on Fas/Fas-ligand and Bcl-2/Bax mRNA expressions in rat hepatic stellate cells.

METHODS: Rat hepatic stellate cells (HSCs) were isolated and purified from rat liver by in situ digestion of collagenase and pronase and single-step density Nycodenz gradient. After activated by culture in vitro, HSCs were divided into 4 groups and treated with nothing (group N), PDGF (group P), IL-10 (group I) and PDGF in combination with IL-10 (group C), respectively. Semi-quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) analysis was employed to compare the mRNA expression levels of Fas/FasL and Bcl-2/Bax in HSCs of each group.

RESULTS: The expression levels of Fas between the 4 groups had no significant differences (P > 0.05). FasL mRNA level in normal culture-activated HSCs (group N) was very low. It increased obviously after HSCs were treated with IL-10 (group I) (0.091 ± 0.007 vs 0.385 ± 0.051, P < 0.01), but remained the low level after treated with PDGF alone (group P) or PDGF in combination with IL-10 (group C). Contrast to the control group, after treated with PDGF and IL-10, either alone or in combination, Bcl-2 mRNA expression was down-regulated and Bax mRNA expression was up-regulated, both following the turn from group P, group I to group C. Expression of Bcl-2 mRNA in group C was significantly lower than that in group P (0.126 ± 0.008 vs 0.210 ± 0.024, P < 0.01). But no significant difference was found between group C and group I, as well as between group I and group P (P > 0.05). Similarly, the expression of Bax in group C was higher than that in group P (0.513 ± 0.016 vs 0.400 ± 0.022, P < 0.01). No significant difference was found between group I and group P (P > 0.05). But compared with group C, Bax expressions in group I tended to decrease (0.449 ± 0.028 vs 0.513 ± 0.016, P < 0.05).

CONCLUSION: PDGF may promote proliferation of HSCs but is neutral with respect to HSC apoptosis. IL-10 may promote the apoptosis of HSCs by up-regulating the expressions of FasL and Bax and down-regulating the expression of Bcl-2, which may be involved in its antifibrosis mechanism.

Lipid metabolism in hepatic steatosis

Hepatic steatosis is a consequence of both obesity and ethanol use. Nonalcoholic steatosis (NASH) resemble alcoholic steatosis and steatohepatitis. Both exhibit increased hepatocellular triglycerides(TG), reflecting an increase in long chain fatty acids (LCFA). LCFA enter cells by both facilitated transport and passive diffusion. A driving force for both is the plasma unbound LCFA concentration ([LCFAu]). In both obese rodents and obese patients, adipocyte LCFA uptake via both facilitated transport and diffusion is increased. However, the LCFA uptake Vmax in hepatocytes is not increased in obese animals. Nevertheless, total LCFA uptake in obese rodents is increased ~3-fold, reflecting increased plasma LCFA concentrations. With advancing obesity, resistance to the antilipolytic effects of insulin results in increased lipolysis within the omental fat depot, a consequent further rise in portal venous LCFA, and an even greater rise in portal [LCFAu]. This causes a further increase in hepatocellular LCFA uptake, increased intracellular generation of reactive oxygen species (ROS), and transition from simple steatosis to NASH. By contrast, in rodent hepatocytes and in human hepatoma cell lines, ethanol up-regulates the LCFA uptake Vmax. Consequently, although plasma LCFA are unaltered, hepatocellular LCFA uptake in ethanol-fed rats is also increased~3-fold, leading to increased ROS generation and evolution of alcoholic hepatitis. Thus, while increased hepatic LCFA uptake contributes to the pathogenesis of both NASH and alcoholic hepatitis,the underlying mechanisms differ. Recognizing these mechanistic differences is important in developing strategies for both prevention and treatment of these conditions.

Effect of rat serum containing Biejiajian oral liquid on proliferation of rat hepatic stellate cells

AIM: Liver fibrosis is a common pathological process of chronic liver diseases. Activation of hepatic stellate cells (HSCs) is the key issue in the occurrence of liver fibrosis. In this study, we observed the inhibitory action of rat serum containing Biejiajian oral liquid (BOL), a decoction of turtle shell, on proliferation of rat HSCs, and to explore the anti-hepatofibrotic mechanisms of BOL.

METHODS: A rat model of hepatic fibrosis was induced by subcutaneous injection of CCl₄. Serum containing low, medium and high dosages of BOL was prepared respectively. Normal and fibrotic HSCs were isolated and cultured. The effect of sera containing BOL on proliferation of HSCs was determined by ³H-TdR incorporation.

RESULTS: The inhibitory rate of normal rat HSC proliferation caused by 100 mL/mL sera containing medium and high dosages of BOL showed a remarkable difference as compared with that caused by colchicine (medium dosage group: 34.56% ± 4.21% vs 29.12% ± 2.85%, P < 0.01; high dosage group: 37.82% ± 1.32% vs 29.12% ± 2.85%, P < 0.01). The inhibitory rate of fibrotic rat HSC proliferation caused by 100 mL/L serum containing medium and high dosages of BOL showed a remarkable difference as compared with that caused by colchicine (medium dosage group: 51.31% ± 3.14% vs 38.32% ± 2.65%, P < 0.01; high dosage group: 60.15% ± 5.36% vs 38.32% ± 2.65%, P < 0.01). The inhibitory rate of normal rat HSC proliferation caused by 100 mL/L and 200 mL/L sera containing a medium dosage of BOL showed a significant difference as compared with that caused by 50 mL/L (100 mL/L group: 69.02% ± 9.96% vs 50.82% ± 9.28%, P < 0.05; 200 mL/L group: 81.78% ± 8.92% vs 50.82% ± 9.28%, P < 0.01). The inhibitory rate of fibrotic rat HSC proliferation caused by 100 mL/L and 200 mL/L sera containing a medium dosage of BOL showed a significant difference as compared with that caused by 50 mL/L (100 mL/L group: 72.19% ± 10.96% vs 61.38% ± 7.16%, P < 0.05; 200 mL/L group: 87.16% ± 8.54% vs 61.38% ± 7.16%, P < 0.01).

CONCLUSION: Rat serum containing BOL can inhibit proliferation of rat HSCs, and the inhibition depends on the dosage and concentration of BOL. The inhibitory effect on HSC proliferation is one of the main anti-hepatofibrotic mechanisms of BOL.

Inhibitory effect of Danshen-containing serum on proliferation of HSC-T6 cells

AIM: To investigate the inhibitory effect of Danshen-containing serum on the proliferation of HSC-T6 cells and to construct anti-hepatic-fibrosis in vitro system for screening potential herbal drugs.

METHODS: The proliferation status of HSC-T6 cells was evaluated by calculating its growth curve and cloning efficiency. HSC-T6 cells were exposed to different volume fractions of Danshen-containing serum, including 80%, 40%, 20%, 10%, and 5% of original serum, and its inhibitory effect and dose-effect relationship were investigated.

RESULTS: The population doubling time of HSC-T6 was 10.57 hours and its cloning efficiency was 82.4%, which showed that this cell line had good capacity of activity and proliferation for tests. Ranging from 5% to 80% of original concentration, Danshen-containing serum had the dose-dependent inhibitory effect on HSC-T6 cell (analysis by linear regression, coefficient of correlation = 0.9487).

CONCLUSION: The Danshen-containing serum has significantly inhibitory effect on proliferation of HSC-T6 cells in a dose-dependent manner.

Suppression of hepatocellular carcinoma growth in mice by the alkaloid coccidiostat halofuginone

Halofuginone, a widely used alkaloid coccidiostat, is a potent inhibitor of collagen alpha 1 (I) and matrix metalloproteinase 2 gene expression. Halofuginone also suppresses extracellular matrix deposition and fibroblast proliferation. It was recently shown to be effective in suppression of bladder carcinoma and glioma. This study sought to evaluate the effect of treatment with halofuginone on growth of hepatocellular carcinoma (HCC) in mice. Athymic Balb/c mice were injected subcutaneously with 10(7) human hepatoma cells (Hep3B), followed by treatment with halofuginone administered in the diet (750 microg/kg) starting on day 3, before tumour innoculation. The control group was received a normal diet. Mice were followed for survival, tumour volume and serum alpha-fetoprotein (alpha FP). The mechanism of the anti-tumour effect of halofuginone was determined in vitro by assessing tumour cell growth, and by measuring the serum concentrations of interferon-gamma (IFN gamma) and interleukin 2 (IL2). Halofuginone treatment induced almost complete tumour suppression in treated mice. Mortality rates were 10% and 50%, in halofuginone-treated and control mice, respectively (P<0.001). No visible tumour was observed in treated mice, as compared with a 364 mm3 tumour in control mice. Serum alpha FP were 0.1 and 212 ng/ml in treated and control mice, respectively (P<0.005). Halofuginone significantly inhibited HCC proliferation in vitro. Maximal inhibition of 64% of tumour cell growth was observed at a concentration of 10(-8) M. The anti-tumour effect was mediated via a significant increase in IFN gamma and IL2 (90 vs. 35, and 210 vs. 34 pg/ml in treated and control groups, respectively, P<0.005). Treatment with halofuginone effectively suppressed the progression of HCC in mice. This effect may be associated with a direct anti-tumour effect, and/or enhancement of a systemic immune response.

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Reversibility of cirrhosis in chronic hepatitis B

BACKGROUND & AIMS

Hepatic fibrosis and cirrhosis are the consequences of many types of chronic liver disease, and, at its final stage when liver nodule and scarring develop, they are generally considered to be irreversible.

METHODS

Here we describe 3 patients with chronic hepatitis B with clinical, biochemical, and histologic evidence of cirrhosis. They underwent treatment with interferon-alpha or lamivudine and had follow-up liver biopsy while in clinical, biochemical, and virologic remission. Biopsy specimens were randomly coded in unpaired manner according to patient, and they were read independently by 2 pathologists using the modified hepatitis activity index (with a maximum stage of 6). The mean interval between biopsies was 5.5 years.

RESULTS

The mean ALT level decreased from 113.7 to 28.3 U/L. The mean bilirubin level decreased from 2.4 to 0.9 mg/dL, and the mean prothrombin time decreased from 16.3 to 12.3 seconds. The mean Child-Pugh score decreased from 8 to 5. The mean fibrosis score decreased from 5.8 to 0.5 (P = 0.004), and the mean grading score decreased from 10.8 to 3.2 (P = 0.017).

CONCLUSIONS

Cirrhosis due to chronic hepatitis B might be reversible in some patients who respond to antiviral therapy.

Dynamic changes of capillarization and peri-sinusoid fibrosis in alcoholic liver diseases

AIM: To investigate the dynamic changes of capillarization and peri-sinusoid fibrosis in an alcoholic liver disease model induced by a new method.

METHODS: Male SD rats were randomly divided into 6 groups, namely normal, 4 d, 2 w, 4 w, 9 w and 11 w groups. The animals were fed with a mixture of alcohol for designated days and then decollated, and their livers were harvested to examine the pathological changes of hepatocytes, hepatic stellate cells, sinusoidal endothelial cells, sinusoid, peri-sinusoid. The generation of three kinds of extra cellular matrix was also observed.

RESULTS: The injury of hepatocytes became severer as modeling going on. Under electronic microscope, fatty vesicles and swollen mitochondria in hepatocytes, activated hepatic stellate cells with fibrils could been seen near or around it. Fenestrae of sinusoidal endothelial cells were decreased or disappeared, sinusoidal basement was formed. Under light microscopy typical peri-sinusoid fibrosis, gridding-like fibrosis, broaden portal areas, hepatocyte’s fatty and balloon denaturation, iron sediment, dot necrosis, congregated lymphatic cells and leukocytes were observed. Type I collagen showed an increasing trend as modeling going on, slightly recovered when modeling stopped for 2 weeks. Meanwhile, type IV collagen decreased rapidly when modeling began and recovered after modeling stopped for 2 weeks. Laminin increased as soon as modeling began and did not recover when modeling stopped for 2 weeks.

CONCLUSION: The pathological changes of the model were similar to that of human ALD, but mild in degree. It had typical peri-sinusoid fibrosis, however, capillarization seemed to be instable. It may be related with the reduction of type IV collagen in the basement of sinusoid during modeling.

Expression of TIMP-1 and TIMP-2 in rats with hepatic fibrosis

AIM: To investigate the location and expression of TIMP-1 and TIMP-2 in the liver of normal and experimental hepatic fibrosis in rats.

METHODS: The rat models of experimental immunity hepatic fibrosis (n = 20) were prepared by the means of immunologic attacking with human serum albumin (HSA), and normal rats (n = 10) served as control group. Both immunohistochemistry and in situ hybridization methods were respectively used to detect the TIMP-1 and TIMP-2 mRNA and related antigens in liver. The liver tissue was detected to find out the gene expression of TIMP-1 and TIMP-2 with RT-PCR.

RESULTS: The TIMP-1 and TIMP-2 related antigens in livers of experimental group were expressed in myofibroblasts and fibroblasts (TIMP-1: 482 ± 65 vs 60 ± 20; TIMP-2: 336 ± 48 vs 50 ± 19, P < 0.001). This was the most obvious in portal area and fibrous septum. The positive signals were located in cytoplasm, not in nucleus. Such distribution and location were confirmed by situ hybridization (TIMP-1/β-actin: 1.86 ± 0.47 vs 0.36 ± 0.08; TIMP-2/β-actin: 1.06 ± 0.22 vs 0.36 ± 0.08, P < 0.001). The expression of TIMP-1 and TIMP-2 was seen in the liver of normal rats, but the expression level was very low. However, the expression of TIMP-1 and TIMP-2 in the liver of experimental group was obviously high.

CONCLUSION: In the process of hepatic fibrosis, fibroblasts and myofibroblasts are the major cells that express TIMPs. The more serious the hepatic fibrosis is in the injured liver, the higher the level of TIMP-1 and TIMP-2 gene expression.

Relationship between clinical and pathologic findings in patients with chronic liver diseases

AIM: To explore the relationship between clinical findings of patients with chronic liver diseases and the pathologic grading and staging of liver tissues.

METHODS: The inflammatory activity and fibrosis of consecutive liver biopsies from 200 patients were determined according to the diagnosis criteria of chronic hepatitis in China established in 1995. A comparative analysis was carried out for 200 patients with chronic liver diseases by comparing their clinical manifestations, serum biochemical markers with the grading and staging of liver tissues.

RESULTS: It was revealed that age, index of clinical symptoms and physical signs were obviously relevant to the pathologic grading and staging of liver tissues (P < 0.05). Blood platelet, red blood cells, aspartate aminotransferase (AST), N-terminal procollagen III (PIII NP) were apparently correlated with the degree of inflammation. PGA (prothrombin time, GGT, apoprotein A1) index, PGAA (PGA + △2-macroglobublin) index, albumin and albumin/globulin were relevant to both inflammation and fibrosis. Hyaluronic acid (HA) was an accurate variable for the severity of hepatic inflammation and fibrosis. The combination of serum markers for fibrosis could increase the diagnostic accuracy. It was notable that viral replication markers were not relevant to the degree of inflammation and fibrosis.

CONCLUSION: There is a good correlation between clinical findings and the pathologic grading and staging of liver tissues, which may give aid to the noninvasive diagnosis of liver fibrosis.

NADPH oxidase signal transduces angiotensin II in hepatic stellate cells and is critical in hepatic fibrosis

Angiotensin II (Ang II) is a pro-oxidant and fibrogenic cytokine. We investigated the role of NADPH oxidase in Ang II-induced effects in hepatic stellate cells (HSCs), a fibrogenic cell type. Human HSCs express mRNAs of key components of nonphagocytic NADPH oxidase. Ang II phosphorylated p47phox, a regulatory subunit of NADPH oxidase, and induced reactive oxygen species formation via NADPH oxidase activity. Ang II phosphorylated AKT and MAPKs and increased AP-1 DNA binding in a redox-sensitive manner. Ang II stimulated DNA synthesis, cell migration, procollagen alpha1(I) mRNA expression, and secretion of TGF-beta1 and inflammatory cytokines. These effects were attenuated by N-acetylcysteine and diphenylene iodonium, an NADPH oxidase inhibitor. Moreover, Ang II induced upregulation of genes potentially involved in hepatic wound-healing response in a redox-sensitive manner, as assessed by microarray analysis. HSCs isolated from p47phox-/- mice displayed a blunted response to Ang II compared with WT cells. We also assessed the role of NADPH oxidase in experimental liver fibrosis. After bile duct ligation, p47phox-/- mice showed attenuated liver injury and fibrosis compared with WT counterparts. Moreover, expression of smooth muscle alpha-actin and expression of TGF-beta1 were reduced in p47phox-/- mice. Thus, NADPH oxidase mediates the actions of Ang II on HSCs and plays a critical role in liver fibrogenesis.

NADPH oxidase signal transduces angiotensin II in hepatic stellate cells and is critical in hepatic fibrosis

Angiotensin II (Ang II) is a pro-oxidant and fibrogenic cytokine. We investigated the role of NADPH oxidase in Ang II-induced effects in hepatic stellate cells (HSCs), a fibrogenic cell type. Human HSCs express mRNAs of key components of nonphagocytic NADPH oxidase. Ang II phosphorylated p47phox, a regulatory subunit of NADPH oxidase, and induced reactive oxygen species formation via NADPH oxidase activity. Ang II phosphorylated AKT and MAPKs and increased AP-1 DNA binding in a redox-sensitive manner. Ang II stimulated DNA synthesis, cell migration, procollagen alpha1(I) mRNA expression, and secretion of TGF-beta1 and inflammatory cytokines. These effects were attenuated by N-acetylcysteine and diphenylene iodonium, an NADPH oxidase inhibitor. Moreover, Ang II induced upregulation of genes potentially involved in hepatic wound-healing response in a redox-sensitive manner, as assessed by microarray analysis. HSCs isolated from p47phox-/- mice displayed a blunted response to Ang II compared with WT cells. We also assessed the role of NADPH oxidase in experimental liver fibrosis. After bile duct ligation, p47phox-/- mice showed attenuated liver injury and fibrosis compared with WT counterparts. Moreover, expression of smooth muscle alpha-actin and expression of TGF-beta1 were reduced in p47phox-/- mice. Thus, NADPH oxidase mediates the actions of Ang II on HSCs and plays a critical role in liver fibrogenesis.

The ethanol metabolite, linolenic acid ethyl ester, stimulates mitogen-activated protein kinase and cyclin signaling in hepatic stellate cells

Chronic ethanol consumption can result in hepatic fibrosis and cirrhosis. In addition to oxidative metabolism, ethanol can be metabolized by esterification with fatty acids to form fatty acid ethyl esters (FAEE) such as linolenic acid ethyl ester (LAEE). We have previously demonstrated that LAEE has promitogeinc and activating effects on hepatic stellate cells (HSC), but the mechanisms of these actions are not known. Intracellular signaling through MAP kinase pathways, including extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) can influence the activity of the transcription factor AP-1, while cell-cycle regulatory proteins such as cyclin E and cyclin-dependent kinase (CDK), play an important role in cell proliferation. In this study, we demonstrate that treatment of HSC with LAEE increases cyclin E expression and cyclin E/CDK2 activity, which may underlie the promitogenic effects of this compound. In addition, LAEE increases ERK and JNK activity, and these pathways play an important role in the activation of AP-1-dependent gene expression by LAEE. The stimulation of intracellular signaling pathways in HSC by this well-characterized ethanol metabolite may contribute to ethanol-induced hepatic fibrogenesis.

Effects of heparin on liver fibrosis in patients with chronic hepatitis B

AIM: To evaluate the effects of heparin on liver fibrosis in patients with chronic hepatitis B.

METHODS: Fifty-two cases under study were divided into two groups, group A and group B. The two groups were given regular treatment and heparin/low molecular weight heparin (LMWH) treatment respectively. Hepatic functions, serum hyaluronic acid (HA) and type IV collagen levels were measured before and after the treatment, and six cases were taken liver biopsy twice.

RESULTS: After treatment, hepatic functions became significantly better in both groups. Serum HA and type IV collagen levels in group B compared with group A, decreased significantly after treatment. Collagen proliferation also decreased in group B after treatment.

CONCLUSION: Heparin/LMWH can inhibit collagen proliferation in liver tissues with hepatitis B.

Liver extracellular matrix in health and disease

Liver fibrosis is the hallmark of every chronic liver disease. It is also the major factor of morbidity and mortality due to the development of cirrhosis and its complications including hepatocellular carcinoma. But even at the beginning of the process of liver fibrosis and due to the strategic position of the extracellular matrix at the interface between blood flow and epithelial compartment, any quantitative or qualitative modification of extracellular matrix will rapidly affect structure and function of the liver. The development of several animal models of liver fibrosis as well as isolation and cultivation of hepatic stellate cells, the major fibrogenic cell type in the liver, led to the gathering of recent knowledge on the mechanism of liver fibrosis. Activation of hepatic stellate cells is a key event in this process and many details on this finely tuned mechanism are now available. In addition to these experimental data, experience from chronic hepatitis C now allows the development of new concepts and perspectives such as liver fibrosis regression and antifibrotic therapies.

L-cysteine administration prevents liver fibrosis by suppressing hepatic stellate cell proliferation and activation

Recent studies showed that the function of some amino acids is not only nutritional but also pharmacological. However, the effects of amino acids on liver fibrosis and hepatic stellate cell (HSC) remain unclear. In this research, as a result of screening of amino acids using liver fibrosis induced by DMN administration, L-cysteine was selected as a suppressor of liver fibrosis. Furthermore, the number of activated HSCs, which increased in the fibrotic liver after DMN administration, was decreased in L-cysteine-fed rats. Treatment of freshly isolated HSCs with L-cysteine resulted in inhibition of the increase in smooth muscle alpha-actin (alphaSMA) expression by HSCs and BrdU incorporation into the activated HSCs. These findings suggest that L-cysteine is effective against liver fibrosis. The mechanism of inhibition of fibrosis in the liver is surmized to be direct inhibition of activated HSC proliferation and HSC transformation by L-cysteine.

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Effect of Oxymatrine on experimental liver fibrosis

AIM: To study the effect of Oxymatrine on liver fibrosis in immunogenic liver fibrosis rat model.

METHODS: Rat liver fibrosis model was induced by human serum albumin (HSA), 60 Wistar rats were randomly divided into 5 groups, control group without any treatment, liver fibrosis model group, oxymatrine preventive group, oxymatrine therapeutic group, and cochicine therapeutic group. The pathological changes of liver were observed by HE and Von-Gieson staining. The expressions of mRNA and proteins of collagen I/III in liver were determined by in situ hybridization and immunohistochemistry.

RESULTS: The liver fibrosis degree and level of mRNA and proteins of collagen I/III in the liver were significantly reduced in the decreasing order in oxymatrine preventive group, oxymatrine therapeutic group, and cochicine therapeutic group.

CONCLUSION: Oxymatrine may inhibit hepatic inflammation and hepatic synthesis of collagen I/III, and thus prevent and inhibit hepatic fibrosis.

Effect of Chinese herb Shuangjiawuling on expression of TIMPs in rat with liver fibrosis

AIM: To explore the effect of Chinese herb Shuangjiawuling in preventing hepatic fibrosis in rat with liver fibrosis.

METHODS: Rat immunogenic liver fibrosis model was induced by administration human serum albumin (HSA 200 g/L) intravenously, 80 rats were randomly divided into 5 groups. Shuangjiawuling was taken orally simultaneously with (group A), immediately after (group B), or 3 months after (group C) administration of HAS intravenously. Colchine tablets were taken orally with the administration of HAS (group D), normal rats were used as control (Group E). The pathological changes of liver tissue were observed by HE and Von-Gieson staining. The hepatic mRNA and protein of TIMP-1 and TIMP-2 were analyzed by in site hybridization and immunohistochemistry.

RESULTS: Hepatic fibrosis developed gradually and became obviously on the third month after administration of HAS. And strong expressions of TIMP-1 and TIMP-2 were observed, however, its expression and hepatic fibrosis were reduced dramatically following administration of Shuangjiawuling and colchine tablets. The effect of Shuangjiawuling in preventing fibrosis was superior to that of colchine tablets (P<0.05), and its effect in group A, B, and C decreased in order.

CONCLUSION: Chinese herb Shuangjiawuling can inhibit the development of hepatic fibrosis and the expression of TIMPs, and promoted the effect of the degradation of the extracellular matrix.

Approaches for treatment of liver fibrosis in chronic hepatitis C

In the past 20 years, the elucidation of the mechanisms responsible for liver fibrogenesis has provided many potential targets for antifibrotic treatments. Difficulty has arisen, however, from the fact that fibrogenesis is part of a general beneficial wound healing process. To be successful, an antifibrotic treatment of HCV might need to be delivered selectively to the hepatic site of fibrogenesis or targeted precisely at an HCV-specific regulatory mechanism. It is likely that in the future, besides viral eradication, another treatment goal in chronic HCV infection will be to reverse existing fibrosis, but considerable work is necessary before making this a reality.

Effects of tetrandrine on calcium and potassium currents in isolated rat hepatocytes

AIM: To study the effects of tetrandrine (Tet) on calcium release-activated calcium current (I_CRAC), delayed rectifier potassium current (I_K), and inward rectifier potassium currents (I_K1) in isolated rat hepatocytes.

METHODS: Hepatocytes of rat were isolated by using perfusion method. Whole cell patch-clamp techniques were used in our experiment.

RESULTS: The peak amplitude of I_CRAC was -508 ± 115 pA (n = 15), its reversal potential of I_CRAC was about 0 mV. At the potential of -100 mV, Tet inhibited the peak amplitude of I_CRAC from -521 ± 95 pA to -338 ± 85 pA (P < 0.01 vs control, n = 5), with the inhibitory rate of 35% at 10 µmol/L and from -504 ± 87 pA to -247 ± 82 pA (P < 0.01 vs control, n = 5), with the inhibitory rate of 49% at 100 µmol/L, without affecting its reversal potential. The amplitude of I_CRAC was dependent on extracellular Ca²⁺ concentration. The peak amplitude of I_CRAC was -205 ± 105 pA (n = 3) in tyrode’s solution with Ca²⁺ 1.8 mmol/L (P < 0.01 vs the peak amplitude of I_CRAC in external solution with Ca²⁺ 10 mmol/L). Tet at the concentration of 10 and 100 µmol/L did not markedly change the peak amplitude of delayed rectifier potassium current and inward rectifier potassium current (P > 0.05 vs control).

CONCLUSION: Tet protects hepatocytes by inhibiting I_CRAC, which is not related to I_K and I_K1.

Liver fibrosis: insights into migration of hepatic stellate cells in response to extracellular matrix and growth factors

BACKGROUND & AIMS

In liver fibrosis, alterations within the space of Disse microenvironment occur and facilitate further progression of chronic liver disease. The normal basement membrane-like matrix present within the space of Disse converts to a matrix rich in fibril-forming collagens during fibrosis.

METHODS

To further understand the pathogenesis of liver fibrosis, we modified an in vitro Boyden chamber system to partially mimic in vivo conditions of hepatic stellate cells (HSCs) during health and disease.

RESULTS

Stimulation of HSCs with platelet-derived growth factor (PDGF)-BB, transforming growth factor (TGF)-beta1, and/or epithelial growth factor (EGF) resulted in an increase in their migratory capacity and up-regulated matrix metalloproteinase (MMP)-2 activity. Migration induced by PDGF-BB was associated with increased proliferation, whereas TGF-beta1/EGF-induced migration was proliferation independent. COL-3, an inhibitor of MMP-2 and MMP-9, inhibited migration of HSCs induced by direct activation of PDGF-BB or TGF-beta1 but had no effect on migration induced by chemotactic stimuli without direct contact, suggesting 2 distinct MMP-dependent and MMP-independent mechanisms of PDGF-BB- or TGF-beta1-induced migration. Additionally, we show that type I collagen by itself induced migration of HSCs. Migration induced by PDGF-BB, TGF-beta1, and collagen I could be inhibited by alpha(1)- and/or alpha(2)-integrin blocking antibodies, collectively suggesting an integrin-dependent, MMP-2-mediated migration of HSCs.

CONCLUSIONS

Basement membrane matrix integrity, composition, and cell-matrix interactions play an important role in anchoring HSCs and preventing them from spreading within the space of Disse and potentially elsewhere in the liver. Additionally, our data provide strong evidence for MMPs in regulation of HSCs migration.

Biochemical markers of fibrosis in patients with chronic hepatitis C: a comparison with prothrombin time, platelet count, and age-platelet index

As an alternative to liver biopsy, an index of five biochemical markers (alpha2-macroglobulin, apolipoprotein A1, haptoglobin, total bilirubin, gamma-glutamyl-transpeptidase) has been shown to predict the severity of hepatitis C-related fibrosis. The objective of this study was to compare this index with other markers frequently used for this purpose (prothrombin time, platelets, age-platelet index). In 323 hepatitis C-infected patients, the discriminative values of these markers for F2-F4 fibrosis (by the METAVIR classification) were compared. By multiple logistic regression analysis, only the five-marker index (P < 0.0001) and prothrombin time (P = 0.02) were independently predictive of F2-F4 fibrosis. For this outcome, the area under the receiver operating characteristic curve was significantly higher for the five-marker index (0.836 +/- 0.024) than the age-platelet index (P = 0.002), and the platelet count and prothrombin time (P < 0.001), indicating greater diagnostic value. The addition of the latter markers to the five-marker index proved unhelpful for increasing its accuracy. In conclusion, an index of five biochemical markers accurately predicts significant hepatitis C-related fibrosis and is superior to traditional markers.

Oltipraz regenerates cirrhotic liver through CCAAT/enhancer binding protein-mediated stellate cell inactivation

Liver cirrhosis (LC) is a chronic disease with high mortality rate. In the United States and Western world as well as Asian countries, LC is the major leading cause of death by disease. Yet, no effective therapeutic agent is available for LC treatment. Laboratory cirrhotic rats produced by dimethylnitrosamine administrations simulate the clinical features of human LC such as mortality, ascites, hepatic parenchymal cell destruction, and formation of connective tissue and nodular regeneration, providing a preclinical model to evaluate therapeutic efficacy of drugs and the underlying mechanisms. Oltipraz [5-(2-pyrazinyl)-4-methyl-1,2-dithiol-3-thione] has been used clinically and is of little toxicity. Comprehensive mechanistic and phase IIa clinical studies supported the notion that oltipraz exerts chemopreventive effects against chemical carcinogenesis. We report here that oltipraz within the clinical dose range regenerates cirrhotic liver in the established LC rats as a result of reduction of the intensities of cirrhotic nodules, elimination of accumulated extracellular matrix, and inactivation of stellate cells, thereby improving survival rate. We also reveal that activation of CCAAT/enhancer binding protein by oltipraz inhibits transforming growth factor b1 gene expression in stellate cells, which provides a molecular target for pharmacological treatment of LC. Oltipraz is the first therapeutic agent that regenerates cirrhotic liver.

Proliferative action of mast-cell tryptase is mediated by PAR2, COX2, prostaglandins, and PPARgamma : Possible relevance to human fibrotic disorders

Mast-cell products can stimulate fibroblast proliferation, implying that these cells are key players in fibrosis. One mast-cell product, the serine protease tryptase, is known to activate protease-activated receptor 2 (PAR2) and cause proliferation of fibroblasts. We found that recombinant tryptase, human mast-cell (HMC-1) supernatant, which contains tryptase, and the PAR2-activating peptide SLIGKV exert fibroproliferative actions in human fibroblasts. Here we report insights into this action, which after activation of PAR2 leads to increased expression of cyclooxygenase 2 (COX2), a key enzyme in the biosynthesis of prostaglandins, and consequently to enhanced prostaglandin synthesis. Subsequent cell proliferation is mediated by the prostaglandin 15-deoxy-Delta(12,14)-prostaglandin J(2), which acts via the nuclear peroxisome proliferator-activated receptor gamma (PPARgamma). Fibroblast proliferation induced by tryptase and PAR2 agonist peptide can be blocked by antagonists of COX2 and PPARgamma, implying that the proliferative effect of tryptase is PAR2-initiated but depends on COX2, 15-deoxy-Delta(12,14)-prostaglandin J(2), and PPARgamma. This previously uncharacterized pathway could be of relevance for human fibrotic diseases. For instance, increased numbers of activated mast cells are correlated with fibrosis in testes of infertile men. In these cases all components of the signaling pathway of tryptase were detected as well as expression of COX2. Therefore, our study describes as-yet-unknown interactions between mast cells and fibroblasts, which could be relevant for human fibrotic diseases.