Interferon gamma treatment prevents procollagen gene expression without affecting transforming growth factor-beta1 expression in pig serum-induced rat liver fibrosis in vivo

A histone deacetylase inhibitor, largazole, decreases liver fibrosis and angiogenesis by inhibiting transforming growth factor-β and vascular endothelial growth factor signalling

BACKGROUND & AIMS

Largazole is a novel histone deacetylase (HDAC) inhibitor. This study investigated the effects of largazole against liver fibrosis.

METHODS

The in vitro effects of largazole were examined using hepatic stellate cells (HSCs). In vivo effects of largazole were studied using a mouse liver fibrotic model induced by CCl4 .

RESULTS

Largazole augmented acetylation of histone H3 (H3) and histone H4 (H4) in HSCs. It directly inhibited the activation of HSCs owing to HDAC inhibitory activity as the antifibrotic effect of largazole was significantly decreased in cells with HDAC1, HDAC2 and HDAC3 knockdown. Largazole also induced apoptosis of HSCs. Largazole not only inhibited the expression of TGFβR2, but also reduced phosphorylation of Smad2 and Akt induced by TGF-β1. Largazole also inhibited the expression of vascular endothelial growth factor (VEGF) and its receptor. VEGF-induced proliferation of HSCs and activation of Akt and p38MAPK were also suppressed by largazole. In vivo, largazole reduced the expression of collagen I, α-smooth muscle actin and tissue inhibitor of metalloproteinase-1 in CCl4 -induced fibrosis, and these antifibrotic effects were associated with increased acetylation of H3 and H4. Largazole also induced HSCs to undergo apoptosis in vivo, which was correlated with downregulation of bcl-2 and bcl-xL. Furthermore, largazole inhibited angiogenesis in vivo as evidenced by reduced expression of CD34, VEGF and VEGFR. In addition to its antifibrotic activity, the drug reduced inflammatory activity in CCl4 -induced liver fibrosis.

CONCLUSIONS

Our findings revealed a novel role of largazole in the treatment of liver fibrosis. Through multiple mechanisms, largazole could be a potentially effective antifibrotic agent.

Inhibition of PDGF, TGF-β, and Abl signaling and reduction of liver fibrosis by the small molecule Bcr-Abl tyrosine kinase antagonist Nilotinib

BACKGROUND & AIMS

Nilotinib is a novel tyrosine kinase inhibitor of Bcr-Abl and other kinases. In this study, we have examined its activity as an anti-fibrotic agent.

METHODS

The in vitro effect of Nilotinib on rat and human HSCs was assessed using proliferation assays and Western blotting. The in vivo antifibrotic efficacy of Nilotinib was assessed in mice with liver fibrosis induced by CCl(4) and bile duct ligation (BDL).

RESULTS

Nilotinib inhibited proliferation, migration, and actin filament formation, as well as the expression of α-SMA and collagen in activated HSCs. Nilotinib induced apoptosis of HSCs, which was correlated with reduced bcl-2 expression, increased p53 expression, cleavage of PARP, as well as increased expression of PPARγ and TRAIL-R. Nilotinib also induced cell cycle arrest, accompanied by increased expression of p27 and downregulation of cyclin D1. Interestingly, Nilotinib not only inhibited activation of PDGFR, but also TGFRII through Src. Nilotinib significantly inhibited PDGF and TGFβ-simulated phosphorylation of ERK and Akt. Furthermore, PDGF- and TGFβ-activated phosphorylated form(s) of Abl in human HSCs were inhibited by Nilotinib. In vivo, Nilotinib reduced collagen deposition and α-SMA expression in CCl(4) and BDL-induced fibrosis. These beneficial effects were associated with suppressed expression of procollagen-(I), TIMP-1, CD31, CD34, VEGF, and VEGFR. Nilotinib could induce HSC undergoing apoptosis in vivo, which was correlated with downregulation of bcl-2. We also observed reduced expression of phosphorylated ERK, Akt, and Abl in the Nilotinib-treated CCl(4) and BDL livers. In addition to its antifibrotic activity, the drug was hepatoprotective and reduced the elevations of ALT and AST after CCl(4) and BDL.

CONCLUSIONS

These studies uncover a novel role of Bcr-Abl activity in treatment of liver fibrosis through multiple mechanisms and indicate that Nilotinib represents a potentially effective antifibrotic agent.

A novel small compound that promotes nuclear translocation of YB-1 ameliorates experimental hepatic fibrosis in mice

Transforming growth factor-β (TGF-β) is considered to be a major factor contributing to liver fibrosis. We have previously shown that nuclear translocation of YB-1 antagonizes the TGF-β/Smad3 signaling in regulating collagen gene expression. More recently, we have demonstrated that the novel small compound HSc025 promotes nuclear translocation of YB-1, resulting in the improvement of skin and pulmonary fibrosis. Here, we presented evidence as to the mechanism by which HSc025 stimulates nuclear translocation of YB-1 and the pharmacological effects of HSc025 on a murine model of hepatic fibrosis. A proteomics approach and binding assays using HSc025-immobilized resin showed that HSc025 binds to the amino acid sequence within the C-tail region of YB-1. In addition, immunoprecipitation experiments and glutathione S-transferase pulldown assays identified poly(A)-binding protein (PABP) as one of the cytoplasmic anchor proteins of YB-1. HSc025 directly binds to YB-1 and interrupts its interaction with PABP, resulting in accelerated nuclear translocation of YB-1. Transfection of cells with PABP siRNA promoted nuclear translocation of YB-1 and subsequently inhibited basal and TGF-β-stimulated collagen gene expression. Moreover, HSc025 significantly suppressed collagen gene expression in cultured activated hepatic stellate cells. Oral administration of HSc025 to mice with carbon tetrachloride-induced hepatic fibrosis improved liver injury as well as the degree of hepatic fibrosis. Altogether, the results provide a novel insight into therapy for organ fibrosis using YB-1 modulators.

Antifibrotic effects of chronic baicalein administration in a CCl4 liver fibrosis model in rats

Baicalein was a major bioactive flavonoid derived from Radix Scutellariae in Xiao-Chai-Hu-Tang which was commonly used to treat chronic hepatitis and liver fibrosis in China. The aim of this study was to assess whether chronic baicalein administration could prevent liver fibrosis induced by carbon tetrachloride (CCl(4)) in rats and investigate its possible protective mechanism. The antifibrotic effects of baicalein were assessed directly by hepatic histology and indirectly by measuring levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), hepatic hyaluronic acid, laminin and procollagen type III (PCIII) in serum, as well as hydroxyproline and matrix metalloproteinases (MMPs) in liver. In addition, we further investigated protein synthesis of platelet derived growth factor (PDGF) beta receptor which has been identified as attractive target for therapeutic intervention. CCl(4) treatment increased levels of AST, ALT, hyaluronic acid, laminin, and PCIII in serum, as well as hydroxyproline and MMPs in liver. Baicalein treatment (20, 40, or 80 mg/kg for 10 weeks) dose-dependently decreased levels of these markers. Baicalein also reduced inflammation, destruction of liver architecture, and collagen accumulation and significantly inhibited protein synthesis of PDGF-beta receptor. Together, our results suggest that chronic baicalein administration inhibits stellate cell activation and proliferation by the down-regulation of PDGF-beta receptor and prevents the development of CCl(4) induced liver fibrosis in rats.

Effect of natural interferon α on proliferation and apoptosis of hepatic stellate cells

Inhibition of the proliferation of hepatic stellate cells (HSC) is clinically important for the control of liver fibrosis and cirrhosis. Interferons are now frequently used for chronic viral hepatitis because of their anti-viral activity. However, patients treated with interferons exhibit a regression of liver fibrosis even if viral eradication is not achieved, indicating that interferon itself has anti-fibrotic activity. Herein, we show the anti-proliferation and pro-apoptotic activity of natural interferon α against HSC. We found that interferon α inhibited serum-stimulated [(3)H]thymidine incorporation of HSC in a dose-dependent manner, with a significant reduction at more than 100 U/ml. Interferon α also attenuated PDGF-BB-stimulated DNA synthesis of HSC. Although the molecular mechanism behind these phenomena has not been defined, we found that interferon α triggers the apoptosis of HSC treated with low-dose tumor necrosis factor α, as determined by the Alamar blue assay, morphology, and DNA ladder formation. Furthermore, interferon α decreased inhibitor of caspase-activated DNase (ICAD) levels, which may augment tumor necrosis factor α-induced cell death signals. Thus, interferon α regulates the number of myofibroblastic hepatic stellate cells and may clinically contribute to the regression of human liver fibrosis.

PTK787/ZK22258 attenuates stellate cell activation and hepatic fibrosis in vivo by inhibiting VEGF signaling

Liver fibrosis due to hepatic stellate cell (HSC) activation represents a common response to chronic liver injury. PTK787/ZK222584 (PTK/ZK) is a pan-VEGFR tyrosine kinase inhibitor. The aim of this study was to examine the effect of PTK/ZK in liver fibrosis. In primary HSCs, PTK/ZK inhibited the expression of alpha-smooth muscle actin (alpha-SMA), collagen, tissue inhibitor of metalloproteinase-1 (TIMP-1), as well as cell proliferation, migration and actin filament formation. PTK/ZK-induced apoptosis of HSCs, which was correlated with increased caspase-3 activation and suppressed Bcl-2 expression. PTK/ZK also induced cell cycle arrest, accompanied by increasing the expression of p27(Kip1) and downregulation of cyclin D1 and cyclin E. PTK/ZK significantly inhibited vascular endothelial growth factor (VEGF) expression, as well as VEGF-simulated cell proliferation and phosphorylation of Akt in activated HSCs. In a murine fibrotic liver, PTK/ZK attenuated collagen deposition and alpha-SMA expression in carbon tetrachloride-induced fibrosis in both a 'prevention' and 'treatment' dosing scheme. These beneficial effects were associated with reduced phosphorylation of Akt and suppressed mRNA expression of procollagen-(I), TIMP-1, matrix metalloproteinase-9 and CD31. These findings provide novel insights into the potential value of blocking VEGF signaling by a small molecule tyrosine kinase inhibitor in treating hepatic fibrosis.

Utility of plasma circulating mRNA as a marker to detect hepatic injury

Utility of plasma circulating mRNA as a molecular marker to detect hepatic injury was evaluated. Total RNA was isolated from plasma of the rat liver fibrosis models at various time points, and plasma circulating mRNAs of major liver-derived genes, albumin and haptoglobin, were measured by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Sensitivity and kinetics of plasma circulating mRNA were compared with those of plasma alanine aminotransferase (ALT) activity. We have found that the measurement of plasma circulating mRNA is more sensitive than plasma ALT activity, and enables early detection of hepatic injury. The plasma circulating mRNA will serve as a novel and highly sensitive molecular marker for hepatic injury.

Liver fibrosis

Liver damage leads to an inflammatory response and to the activation and proliferation of mesenchymal cell populations within the liver which remodel the extracellular matrix as part of an orchestrated wound-healing response. Chronic damage results in a progressive accumulation of scarring proteins (fibrosis) that, with increasing severity, alters tissue structure and function, leading to cirrhosis and liver failure. Efforts to modulate the fibrogenesis process have focused on understanding the biology of the heterogeneous liver fibroblast populations. The fibroblasts are derived from sources within and out with the liver. Fibroblasts expressing alpha-smooth muscle actin (myofibroblasts) may be derived from the transdifferentiation of quiescent hepatic stellate cells. Other fibroblasts emerge from the portal tracts within the liver. At least a proportion of these cells in diseased liver originate from the bone marrow. In addition, fibrogenic fibroblasts may also be generated through liver epithelial (hepatocyte and biliary epithelial cell)-mesenchymal transition. Whatever their origin, it is clear that fibrogenic fibroblast activity is sensitive to (and may be active in) the cytokine and chemokine profiles of liver-resident leucocytes such as macrophages. They may also be a component driving the regeneration of tissue. Understanding the complex intercellular interactions regulating liver fibrogenesis is of increasing importance in view of predicted increases in chronic liver disease and the current paucity of effective therapies.

Cisplatin (CDDP)-induced acute toxicity in an experimental model of hepatic fibrosis

Cisplatin (CDDP)-induced acute toxicity was investigated in an experimental model of liver fibrosis produced through repeated intraperitoneal injections of swine serum in rats. A significant increase in level of hepatic markers, such as plasma ASAT, LDH, glucose, total cholesterol and bile acid levels, and a significant decrease in the plasma triacylglycerol level were observed. Slight histological changes, such as necrosis, vacuolar degeneration, and the proliferation of bile ducts were observed as compared with the control fibrotic rats. On the other hand, a significant increase in levels of renal markers, such as plasma BUN and creatinine levels as well as more remarkable tubular degeneration were observed. From these results, CDDP's hepatotoxicity was slight while its nephrotoxicity was more extensive in fibrotic rats.

Rating of CCl(4)-induced rat liver fibrosis by blood serum glycomics

BACKGROUND

Non-invasive staging of human liver fibrosis is a desirable objective that remains under extensive evaluation. Animal model systems are often used for studying human liver disease and screening antifibrotic compounds. The aim of the present study was to investigate the potential use of serum N-glycan profiles to evaluate liver fibrosis in a rat model.

METHODS

Liver fibrosis and cirrhosis were induced in rats by oral administration of CCl(4). Liver injury was assessed biochemically (alanine aminotransferase [ALT] activity, aspartate aminotransferase [AST] activity and total bilirubin) and histologically. The N-glycan profile (GlycoTest) was performed using DNA sequencer-assisted-fluorophore-assisted carbohydrate electrophoresis technology. In parallel, the effect of cotreatment with antifibrotic interferon-gamma (IFN-gamma) was studied.

RESULTS

The biopsy scoring system showed that CCl(4) induced early fibrosis (F < 1-2) in rats after 3 weeks of treatment, and cirrhosis (F4) after 12 weeks. Significant increases in ALT activity, AST activity and total bilirubin levels were detected only after 12 weeks of CCl(4) treatment. GlycoTest showed three glycans were significantly altered in the CCl(4)-goup. Peak 3 started at week 6, at an early stage in fibrosis development (F < 1-2), whereas peaks 4 and 5 occurred at week 9, at which time mild liver fibrosis (F = 1-2) had developed. The changes in the CCl(4)-IFN-gamma group were intermediate between the CCl(4)- and the control groups.

CONCLUSION

The GlycoTest is much more sensitive than biochemical tests for evaluating liver fibrosis/cirrhosis in the rat model. The test can also be used as a non-invasive marker for screening and monitoring the antifibrotic activity of potential therapeutic compounds.

IFN-gamma abrogates profibrogenic TGF-beta signaling in liver by targeting expression of inhibitory and receptor Smads

BACKGROUND/AIMS

In a randomized open-labeled multicenter trial with patients suffering from chronic HBV infection, we recently identified a benefit of 9-month IFN-gamma treatment resulting in decreased fibrosis scores and a reduced number of alpha-smooth muscle actin-positive hepatic stellate cells (HSCs). Approaches opposing profibrogenic activities of TGF-beta may be amenable in chronic liver disease. According to experimental models, IFN-gamma counteracts several TGF-beta effects.

METHODS

The crosstalk of IFN-gamma and TGF-beta signaling relevant for fibrogenesis was investigated in primary cultured rat HSCs and a cell line representing activated HSCs.

RESULTS

In vitro studies with HSCs demonstrate that TGF-beta-dependent activation of (CAGA)9-MLP-Luc, a Smad3/4 responsive reporter construct, was significantly decreased by IFN-gamma, indicating a TGF-beta antagonizing function. IFN-gamma induced the activity of the Smad7 promoter and Smad7 protein expression via STAT-1 signaling. In contrast to TGF-beta, IFN-gamma was able to induce Smad7 expression in activated HSCs providing increased protein levels for at least 12h. In addition, expression of Smad2/3 was reduced by IFN-gamma and activation of Smads2/3 was abrogated.

CONCLUSIONS

IFN-gamma displays antifibrotic effects in liver cells via STAT-1 phosphorylation, upregulation of Smad7 expression and impaired TGF-beta signaling.

Attenuated liver progenitor (oval) cell and fibrogenic responses to the choline deficient, ethionine supplemented diet in the BALB/c inbred strain of mice

BACKGROUND/AIMS

Liver regeneration following chronic injury is associated with inflammation, the proliferation of liver progenitor (oval) cells and fibrosis. Previous studies identified interferon-gamma as a key mediator of oval cell proliferation. Interferon-gamma is known to regulate Th1 cell activities during immune challenge. Therefore, we hypothesised that progenitor cell-mediated regeneration is associated with a Th1 immune response.

METHODS

C57Bl/6 (normal Th1 response) and BALB/c mice (deficient in Th1 signalling) were placed on a carcinogenic diet to induce liver injury, progenitor cell proliferation and fibrosis.

RESULTS

Serum transaminases and mortality were elevated in BALB/c mice fed the diet. Proliferation of liver progenitor cells was significantly attenuated in BALB/c animals. The pattern of cytokine expression and inflammation differed between strains. Liver fibrosis and hepatic stellate cell activation were significantly inhibited in BALB/c mice compared to C57Bl/6. In addition, interferon-gamma knockout mice also showed reduced fibrosis compared to wild type. These findings are in contrast to published results, in which interferon-gamma is shown to be anti-fibrogenic.

CONCLUSIONS

Our data demonstrate that the hepatic progenitor cell response to a CDE diet is inhibited in mice lacking Th1 immune signalling and further show that this inhibition is associated with reduced liver fibrosis.

T cell immune response is correlated with fibrosis and inflammatory activity in hepatitis B cirrhotics

AIM: To explore the relationship among interferon-γ (IFN-γ) activity, fibrogenesis, T cell immune responses and hepatic inflammatory activity.

METHODS: Peripheral blood samples from a total of 43 hepatitis B cirrhotic patients (LC) and 19 healthy controls (NC) were collected to measure their serum levels of IFN-γ, interleukin-2 (IL-2), soluble interleukin-2 receptor (sIL-2R), interleukin-10 (IL-10) and three serological markers of fibrosis including hyaluronic acid (HA), procollagen type III peptide (PIIIP), and type IV collagen were measured using a double antibody sandwich ELISA. Also, serum total bilirubin (TB) and alanine aminotransferase (ALT) were measured by routine measures.

RESULTS: The concentrations of serological markers of fibrosis in patients with active cirrhosis (ALC) were significantly higher than those in stationary liver cirrhosis (SLC) or NC groups. The levels of serological markers in HBeAg-positive patients were significantly higher than those in HBeAg-negative patients. In SLC and ALC patients, a negative linear correlation was found between IFN-γ levels and the serological markers of fibrosis. IFN-γ and IL-2 levels in the ALC group were significantly higher than those in the SLC and NC groups, but the statistical difference was not significant between the latter two. In contrast, IL-10 levels in the SLC group were significantly higher than that in the NC group, but no significant difference was found between SLC and ALC groups. The sIL-2R level was elevated gradually in all these groups, and the differences were significant. Positive linear correlations were seen between IFN-γ activity and ALT levels (r = 0.339, P < 0.05), and IL-2 activity and TB levels (r = 0.517, P < 0.05). sIL-2R expression was positively correlated with both ALT and TB levels (r = 0.324, 0.455, P < 0.05), whereas there was no statistically significant correlation between IL-10 expression and serum ALT and TB levels (r = -0.102, -0.093, P > 0.05). Finally, there was a positive correlation between IFN-γ and IL-2 levels.

CONCLUSION: T cell immune responses are correlated with fibrosis and hepatic inflammatory activity and may play an important role in liver cirrhosis.

Interferon gamma-1b for the treatment of fibrosis in chronic hepatitis C infection

Given that the complications of hepatitis C are due to fibrosis, we hypothesized that the antifibrotic effects of interferon gamma on stellate cells would lead to beneficial effects in patients with hepatitis C. Thus, we evaluated the safety and efficacy of interferon gamma-1b in patients with hepatitis C. A cohort of 20 patients with chronic hepatitis C who failed or were intolerant to previous interferon-alpha-based regimens received 200 mug of interferon gamma-1b subcutaneously three times weekly for 24 weeks. Liver biopsy was performed prior to and at the end of treatment. Biopsies were evaluated by a single blinded pathologist using the Knodell system modified by Ishak, and fibrosis was also quantitated by morphometric analysis. The study population was 75% male and 70% Caucasian. Mean age was 47.9 +/- 7.5 years. Eighteen of 20 patients completed therapy. One patient discontinued therapy because of constitutional symptoms. One patient discontinued therapy because of elevated aminotransferases greater than twice baseline. No serious adverse events occurred. Morphometric analysis revealed that six patients (30%) had >1% absolute reduction in fibrosis score. Four of 20 (20%) patients had improvement in Ishak fibrosis scores after treatment. In conclusion, interferon gamma therapy is safe and well tolerated in patients with chronic hepatitis C. Although we did not detect an overall reduction in fibrosis, interferon gamma-1b treatment led to a reduction in fibrosis in selected patients. These data provide a basis for further study of interferon gamma-1b in patients with chronic fibrosing liver disease.

Distinctive role of Stat3 and Erk-1/2 activation in mediating interferon-gamma inhibition of TGF-beta1 action

Interferon-gamma (IFN-gamma) is a multifunctional cytokine that elicits antifibrotic activity in a variety of organs. In this study, we investigated the potential role and mechanism of IFN-gamma in modulating the fibrogenic action of transforming growth factor (TGF)-beta(1) in tubular epithelial cells. Incubation of human proximal tubular epithelial (HKC) cells with IFN-gamma inhibited TGF-beta(1)-mediated alpha-smooth muscle actin (alpha-SMA) expression. IFN-gamma also abolished TGF-beta(1)-induced fibronectin and plasminogen activator inhibitor-1 (PAI-1) expression. To explore the mechanisms by which INF-gamma inhibits TGF-beta(1) action, the signaling pathways that are critical for mediating the antifibrotic activity of IFN-gamma were studied. Stimulation of HKC cells with IFN-gamma triggered a sustained activation of Erk-1/2 and signal transducer and activator of transcription-3 (Stat3). Blockade of Erk-1/2 activation with an Mek1 inhibitor abolished the inhibitory effect of IFN-gamma on alpha-SMA expression, whereas inhibition of Stat3 activation had no influence. Constitutive activation of Erk-1/2 by ectopic expression of activated Mek1 mimicked IFN-gamma and suppressed TGF-beta(1)-mediated alpha-SMA expression. Interestingly, inhibition of Stat3 activation abolished the ability of IFN-gamma to attenuate TGF-beta(1)-mediated PAI-1 and fibronectin expression in HKC cells. These findings indicate that IFN-gamma is capable of antagonizing the fibrogenic actions of TGF-beta(1) in renal tubular epithelial cells. The antifibrotic action of IFN-gamma appears to be mediated through a coordinated activation of both Erk-1/2 and Stat3 signal pathways in a mutually independent fashion.

Adeno-associated virus mediated interferon-gamma inhibits the progression of hepatic fibrosis in vitro and in vivo

AIM: To investigate the effects of adeno-associated virus (AAV) mediated expression of human interferon-γ for gene therapy in experimental hepatic fibrosis in vitro and in vivo.

METHODS: We constructed the recombinant AAV encoding human INF-γ (rAAV- INF-γ) and took the primary rat hepatic stellate cells and carbon tetrachloride induced rats as the experimental hepatic fibrosis model in vitro and in vivo. Immunocytochemistry analysis was used to reveal the expression of α-SMA, the marker protein expressed in hepatic stellate cells. The mRNA expression of TGF-β, TIMP-1, and MMP-13 were analyzed by RT-PCR method. In vivo study, the hydroxyproline content in liver and serum AST, ALT were also detected.

RESULTS: in vitro study, AAV vector could mediated efficient expression of human INF-γ, which inhibit the activation of hepatic stellate cells, decrease the expression of α-SMA and mRNA of TIMP-1, TGF-β, with the MMP-13 unchanged. In vivo study, the histological examination revealed that rAAV- INF-γ could inhibit the progression of the hepatic fibrosis. In the rAAV-INF-γ induced group, the hydroxyproline content and serum AST, ALT level were decreased to 177 ± 28 µg/g wet liver, 668.5 ± 140.0, 458.4 ± 123.5 U/L, compare with the fibrosis control group 236 ± 31 µg/g wet liver, 1 019.1 ± 276.3, 770.5 ± 154.3 U/L, respectively (P < 0.01). mRNA expression of TIMP-1 in the rAAV-INF-γ induced rat liver was decreased while no significant change was observed in TGF-β and MMP-13.

CONCLUSION: All these results indicated that rAAV-INF-γ has potential effects for gene therapy of hepatic fibrosis, which could inhibit the progression of hepatic fibrosis.

Cell type-specific intervention of transforming growth factor beta/Smad signaling suppresses collagen gene expression and hepatic fibrosis in mice

BACKGROUND & AIMS

Transforming growth factor beta and its intracellular mediators, Smad proteins, play important roles in stimulating collagen gene transcription and, thus, could be the targets for treating hepatic fibrosis. However, intervention of transforming growth factor beta/Smad signaling affects physiological signal transduction as well and may cause serious adverse effects on clinical application. Here we have attempted to suppress hepatic fibrosis by expressing a transforming growth factor beta/Smad antagonist selectively in collagen-producing cells only in the fibrotic liver.

METHODS

Recombinant adenoviruses expressing either green fluorescent protein or a transforming growth factor beta/Smad signal repressor, YB-1, were injected into mice untreated or treated with carbon tetrachloride. Green fluorescent protein expression was analyzed under a confocal laser scanning microscope. Antifibrotic effects of YB-1 overexpression were examined by luciferase assays and histological examination with transgenic reporter mice.

RESULTS

When the CAG expression unit was used as a control, green fluorescent protein was strongly expressed in a large number of hepatocytes in both normal and carbon tetrachloride-treated liver. In contrast, green fluorescent protein expression driven by a tissue-specific enhancer of the mouse alpha2(I) collagen gene ( COL1A2 ) was detected in activated hepatic stellate cells in carbon tetrachloride-induced fibrotic liver, but not in untreated normal liver. No green fluorescent protein fluorescence was observed in any other organs when the COL1A2 enhancer was used. Adenovirus-mediated YB-1 expression under the control of the COL1A2 enhancer significantly decreased COL1A2 promoter activity after carbon tetrachloride injection and subsequently suppressed the progression of hepatic fibrosis.

CONCLUSIONS

These results validate a new concept of the therapy for hepatic fibrosis to achieve cell type-specific gene expression only in the fibrotic liver, with little damage to other organs.

Treatment of pig serum-induced rat liver fibrosis with Boschniakia rossica, oxymatrine and interferon-α

AIM: To investigate the effect of Boschniakia rossica (BR), oxymatrine (OM) and interferon-alpha (IFN-α) 1b on the therapy of rat liver fibrosis and its mechanism.

METHODS: By establishing a rat model of pig serum-induced liver fibrosis, liver/weight index and serum alanine transaminase (ALT) were observed to investigate the therapeutic effect of BR,OM and IFN-α. Radioimmunoassay was utilized to measure procollagen type III (PCIII) and collagen type IV (CIV). RT-PCR was used to assay the expression of liver transforming growth factor- beta 1 (TGF-β1) mRNA. Immunohistochemistry of alpha-smooth muscle actin (α-SMA) and pathologic changes of liver tissues were also under investigation.

RESULTS: Serum PCIII and CIV in BR, OM and IFN-α groups were significantly declined compared with those in model group, and their RT-PCR revealed that TGF-β1 mRNA expression was also reduced more than that in model group. Immunohistochemistry demonstrated that α-SMA also declined more than that in model group. Serum ALT in IFN-α, control and model groups was within normal level. Serum ALT in BR group had no significant difference from those of IFN-α, control and model groups. Serum ALT in OM group was significantly higher than those in BR, IFN-α, model, and control groups.

CONCLUSION: BR, OM and IFN-α can prevent pig serum-induced liver rat fibrosis by inhibiting the activation of hepatic stellate cells and synthesizing collagen. OM has hepatotoxicity to rat liver fibrosis induced by pig serum.

Effect of interferon-gamma treatment on 24-hour variations in plasma ACTH, growth hormone, prolactin, luteinizing hormone and follicle-stimulating hormone of male rats

OBJECTIVE

Interferon-gamma (IFN-gamma) is a cytokine produced by T helper cells on antigenic challenge that may affect the release of several pituitary hormones. However, in vitro or in vivo studies have yielded disparate results with stimulatory, inhibitory or absent effects of IFN on pituitary hormone release. One of the reasons for these discrepancies could be that hormone changes were commonly assessed at a single time point in the day-night cycle. In this study we measured the circadian pattern of plasma ACTH, growth hormone (GH), prolactin, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) at 6 different time points within a 24-hour cycle in adult male Wistar rats.

METHODS

Groups of 6-8 rats kept under light from 08:00 to 20:00 h daily received 5 daily injections intraperitoneally of human IFN-gamma (10(5) IU/kg body weight) or saline at 08:30 h. Plasma ACTH, GH, prolactin, LH and FSH levels were measured by a homologous specific double antibody RIA.

RESULTS

A factorial ANOVA for main effects indicated a significant 43% increase of circulating prolactin in IFN-gamma-treated rats. Time of day changes were significant for the five hormones examined and these diurnal variations became altered by IFN-gamma administration, with a phase advance of ACTH peak, a suppression of the rest phase peak of GH, the appearance of a second peak of prolactin at an early phase of daily photoperiod, and the blunting of the 24-hour variations of plasma FSH.

CONCLUSION

The data point out an effect of IFN-gamma on the mechanisms responsible for the circadian organization of pituitary hormone release.

Increases in fibrosis-related gene transcripts in livers of dimethylnitrosamine-intoxicated rats

Fibrosis-related changes in livers of cirrhotic rats induced by dimethylnitrosamine (DMN) have not yet been fully clarified. The aim of this study was to investigate changes in molecular and biochemical markers in DMN-intoxicated rats. DMN was administered to Sprague-Dawley rats for 2 and 5 weeks to induce different degrees of hepatic fibrosis. Liver tissues were assessed for the degree of fibrosis and gene expression. Histological examination of the liver showed a progressive increase in fibrosis scores (1.33 +/- 0.21 and 3.03 +/- 0.29, respectively) and expansion of fibrous septa with collagen-staining fibers in rats after 2 and 5 weeks of DMN administration. Hepatic protein contents of alpha-smooth muscle actin (alpha-SMA) and total collagen were significantly higher in rats administered DMN for both 2 and 5 weeks compared with those in control rats. Hepatic mRNA expressions of alpha-SMA, transforming growth factor-beta1 (TGF-beta1), connective tissue growth factor, tissue inhibitor of metalloproteinase-1, and procollagen I and III were increased in DMN rats after 2 and 5 weeks. Abnormal increases in plasma alanine transaminase (ALT) and aspartate transaminase (AST) levels, plasma and mitochondrial MDA levels, and portal venous pressure were also noted in DMN rats. DMN administration to rats for 2 and 5 weeks induced progressive increases in hepatic fibrosis scores, hepatic mRNA expressions of TGF-beta1 and procollagen I and III genes, plasma levels of ALT and AST, and portal venous pressure, as well as progressive decreases in both liver and body weights. Our results suggest that DMN administration in rats induces biochemical and molecular changes related to fibrogenesis in the liver.

Transplantation of bone marrow cells reduces CCl4-induced liver fibrosis in mice

We investigated the effect of bone marrow cell (BMC) transplantation on established liver fibrosis. BMCs of green fluorescent protein (GFP) mice were transplanted into 4-week carbon tetrachloride (CCl4)-treated C57BL6 mice through the tail vein, and the mice were treated for 4 more weeks with CCl4 (total, 8 weeks). Sirius red and GFP staining clearly indicated migrated BMCs existing along with fibers, with strong expression of matrix metalloproteinase (MMP)-9 shown by anti-MMP-9 antibodies and in situ hybridization. Double fluorescent immunohistochemistry showed the expression of MMP-9 on the GFP-positive cell surface. Film in situ zymographic analysis revealed strong gelatinolytic activity in the periportal area coinciding with the location of MMP-9-positive BMCs. Four weeks after BMC transplantation, mice had significantly reduced liver fibrosis, as assessed by hydroxyproline content of the livers, compared to that of mice treated with CCl4 alone. Subpopulation of Liv8-negative BMCs was responsible for this fibrolytic effect. In conclusion, mice with BMC transplants with continuous CCl4 injection had reduced liver fibrosis and a significantly improved survival rate after BMC transplantation compared with mice treated with CCl4 alone. This finding introduces a new concept for the therapy of liver fibrosis.

Effects of Hochu‐ekki‐to and Ninjin‐youei‐to, Traditional Japanese Medicines, on Porcine Serum‐Induced Liver Fibrosis in Rats

In this study, we estimated the effects of traditional Japanese medicines on liver fibrosis in Wistar rats injected with porcine serum twice a week for 8 weeks. The rats were orally administered Hochu-ekki-to, Ninjin-youei-to (100 and 300 mg/kg/day) or Sho-saiko-to (300 mg/kg/day) 5 days per week. Serum and liver samples were obtained 2 days after the last porcine serum injection. Hochu-ekki-to and Ninjin-youei-to showed significant suppressive effects on the increase in hepatic hydroxyproline, namely total collagen. Further, Ninjin-youei-to significantly suppressed the increases of type IV collagen localized in the basement membrane and prolyl 4-hydroxylase, a collagen synthesis enzyme, in serum or liver. Hochu-ekki-to showed a similar trend. Although Sho-saiko-to did not significantly suppress the increase in hepatic hydroxyproline, it intensely suppressed serum type IV collagen. Further, Hochu-ekki-to, Ninjin-youei-to, and Sho-saiko-to inhibited the production of fibrogenic cytokines, namely TGF-beta1 and IL-13, in the serum and liver. Additionally, we showed that IL-13 levels were positively correlated with hydroxyproline contents in the liver. These results suggest that Ninjin-youei-to as well as Hochu-ekki-to suppress porcine serum-induced liver fibrosis more effectively than Sho-saiko-to. The effects of these three medicines probably depend on the inhibition of fibrogenic cytokine production, resulting in the suppression of collagen synthesis and deposition in the liver, though different mechanisms underlie their anti-fibrogenic effects.

The nuclear receptor SHP mediates inhibition of hepatic stellate cells by FXR and protects against liver fibrosis

BACKGROUND AND AIMS

The farnesoid X receptor (FXR) is an endogenous sensor for bile acids and inhibits bile acid synthesis by inducing small heterodimer partner (SHP) gene expression. The aim of this study was to investigate whether FXR is expressed by and modulates function of hepatic stellate cells (HSCs).

METHODS

The antifibrotic activity of FXR ligand was tested in 2 rodent models: the porcine serum and bile duct ligation (BDL).

RESULTS

Twelve-week administration of 1-10 mg/kg 6-ethyl chenodeoxycholic acid (6-ECDCA), a synthetic FXR ligand, to porcine serum-treated rats prevented liver fibrosis development and reduced liver expression of alpha1(I) collagen, TGF-beta1 and alpha-SMA mRNA by approximately 90%. Therapeutic administration of 6-ECDCA, 3 mg/kg, to BDL rats reduced liver fibrosis and alpha1(I) collagen, transforming growth factor (TGF)-beta1, alpha-SMA, and tissue metalloproteinase inhibitor (TIMP)-1 and 2 messenger RNA (mRNA) by 70%-80%. No protection was observed in BDL rats treated with CDCA, 3 mg/kg, and ursodeoxycholic acid, 15 mg/kg. FXR expression was detected in HSCs. Exposure of HSCs to FXR ligands caused a 3-fold increase of SHP, reduced alpha1(I)collagen and TGF-beta1 by approximately 60%-70% and abrogates alpha1(I) collagen mRNA up-regulation induced by thrombin and TGF-beta1. By retrovirus infection and small interference RNA, we generated SHP overexpressing and SHP-deficient HSC-T6. Using these cell lines, we demonstrated that SHP binds JunD and inhibits DNA binding of adaptor protein (AP)-1 induced by thrombin.

CONCLUSIONS

By demonstrating that an FXR-SHP regulatory cascade promotes resolution of liver fibrosis, this study establish that FXR ligands might represent a novel therapeutic option to treat liver fibrosis.

Establishment of an immortalized human hepatic stellate cell line to develop antifibrotic therapies

Because human hepatic stellate cells (HSCs) perform a crucial role in the progress of hepatic fibrosis, it is of great value to establish an immortalized human cell line that exhibits HSC characteristics and grows well in tissue cultures for the development of antifibrotic therapies. Thus, we engineered an immortalized human hepatic stellate cell (HSC) line TWNT-4 by retrovirally inducing human telomerase reverse transcriptase (hTERT) into LI 90 cells established from a human liver mesenchymal tumor. Parental LI 90 entered replicative senescence, whereas TWNT-4 showed telomerase activity and proliferated for more than population doubling level (PDL) 200 without any crisis. TWNT-4 expressed platelet-derived growth factor-beta receptor (PDGF-betaR), alpha-smooth muscle actin (alpha-SMA), and type I collagen (alpha1) and was considered to be an activated form of HSCs. Treatment of TWNT-4 cells with either 100 U/ml of IFN-gamma or 1 ng/ml of rapamycin (Rapa) for 14 days led to lower expression of type I collagen (alpha1) at RNA and protein levels. Exposure of TWNT-4 cells to both of IFN-gamma (10 U/ml) and Rapa (0.1 ng/ml) for 14 days effectively decreased the expression of type I collagen (alpha1), PDGF-betaR, and alpha-SMA expression and suppressed TGF-beta1 secretion of TWNT-4 cells. We successfully induced apoptosis by transducing TNF-related apoptosis-inducing ligand (TRAIL) into TWNT-4 cells using adenovirus vectors Ad/GT-TRAIL and Ad/PGK-GV-17. These findings suggested that immortalized activated HSC line TWNT-4 would be a useful means to develop antifibrotic therapies.

Interferon alfa down-regulates collagen gene transcription and suppresses experimental hepatic fibrosis in mice

The equilibrium between the production and degradation of collagen is rigorously controlled by a number of growth factors and cytokines. Interferon alfa (IFN-alpha) is now widely used for the treatment of chronic hepatitis C, which can improve serum levels of fibrotic markers and the degree of hepatic fibrosis, not only in patients who responded to therapy but also in those in whom it is ineffective. These findings may suggest that IFN-alpha possesses direct antifibrotic effects in addition to its antiviral activity. However, in contrast to IFN-gamma, which has been shown to suppress collagen gene transcription, little is known about the mechanisms responsible for the antifibrotic effects of IFN-alpha. Here, we report that IFN-alpha, when administered into transgenic mice harboring the alpha2(I) collagen gene (COL1A2) promoter sequence, significantly repressed promoter activation and prevented the progression of hepatic fibrosis induced by carbon tetrachloride injection. Transient transfection assays indicated that IFN-alpha decreased the steady-state levels of COL1A2 messenger RNA (mRNA) and inhibited basal and TGF-beta/Smad3-stimulated COL1A2 transcription in activated hepatic stellate cells (HSC). These inhibitory effects of IFN-alpha on COL1A2 transcription were exerted through the interaction between phosphorylated Stat1 and p300. Blocking of the IFN-alpha signal by overexpressing the intracellular domain-deleted IFN receptor increased basal COL1A2 transcription and abolished the inhibitory effects of IFN-alpha. In conclusion, our results indicate that IFN-alpha antagonizes the TGF-beta/Smad3-stimulated COL1A2 transcription in vitro and suppresses COL1A2 promoter activation in vivo, providing a molecular basis for antifibrotic effects of IFN-alpha.

Leptin receptor-deficient Zucker (fa/fa) rat retards the development of pig serum-induced liver fibrosis with Kupffer cell dysfunction

The aim of this study was to investigate the role of leptin in the development of liver fibrosis with Kupffer cell function using leptin receptor deficient rats. Male Zucker (fa/fa) and control (fa/-) rats received pig serum for 8 weeks. Animals were sacrificed to estimate the degree of liver fibrosis and stellate cell activation with the expression of alpha smooth muscle actin (alphaSMA). Microarray analysis was performed. Isolated Kuppfer cells of Zucker and control rats were treated with LPS. LPS uptake and TNF-alpha production were examined. Stellate cells were also isolated from Zucker and control rats. The expression of procollagen type I mRNAs was examined. Control rats developed liver fibrosis 8 weeks after injection of pig serum and showed an increased liver hydroxyproline content of 348 +/- 34 microg/g (n = 10) compared with Zucker rats (225 +/- 13, n = 10, P < 0.01). The procollagen type I mRNA level and alphaSMA expression of Zucker rats were also significantly reduced. Microarray analysis indicated significantly reduced expression of TNF-alpha, LPS-binding protein, urokinase-type plasminogen activator (uPA), IGF, IGF-binding protein (IGFBP)-3,5, and increased expression of apolipoprotein IV. Isolated Kupffer cells of Zucker rats showed significantly reduced LPS uptake as well as TNF-alpha production compared with control rats. However, no significant change was observed in procollagen type I mRNA levels of isolated stellate cells after 4 days of culture on plastic dishes. These results suggest that leptin receptor deficiency retards the development of liver fibrosis due to the dysfunction of Kuppfer cells.

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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.

Oxidative-stress-related changes in the livers of bile-duct-ligated rats

The role of reactive oxygen species in liver fibrogenesis is not yet clarified. The aim of this study was to investigate oxidative-stress-related changes in cirrhotic rats. Cirrhosis was induced by bile duct ligation in Sprague-Dawley rats. Plasma malondialdehyde (MDA), hepatic 8-hydroxy-2'-deoxyguanosine (8-OHdG), hepatic mitochondrial respiratory functions and gene transcripts were measured at 2 and 4 weeks after surgery in bile-duct-ligated (BDL) and sham-operated-operated rats. The results showed progressive increases in the levels of plasma MDA, hepatic 8-OHdG and procollagen I and III mRNA expression, and progressive impairment of hepatic mitochondrial respiratory function in BDL rats at 2 and 4 weeks after ligation compared with sham-operated rats. Moreover, at 4 weeks after ligation, BDL rats exhibited reduced plasma glutathione and vitamin E levels, impaired hepatic mitochondrial electron transport enzyme activities and oxidative phosphorylation function. In addition, hepatic mRNA expression of transforming growth factor-beta1 was increased. Hepatomegaly, abnormal plasma alanine transaminase and aspartate transaminase levels, and portal hypertension were noted in BDL rats. Our results suggest that bile duct ligation in the rat induces mitochondrial dysfunction and biochemical and molecular changes related to oxidative stress in the liver.

Gadolinium chloride reverses dimethylnitrosamine (DMN)-induced rat liver fibrosis with increased matrix metalloproteinases (MMPs) of Kupffer cells

The aim of this study was to investigate whether matrix metalloproteinases (MMP-13, 9) of Kupffer cells induced by gadolinium chloride (GdCl(3)) treatment can reverse dimethylnitrosamine (DMN)-induced liver fibrosis (in vivo) and the effect of GdCl(3) on MAP kinase activity (in vitro). Male Wistar rats 6 weeks of age received DMN (10 mg/kg) three successive days a week for 4 weeks. Then two groups of rats (n = 6 each) were treated twice weekly with either GdCl(3) (7 mg/kg) or saline solution intravenously for the next 4 weeks. Animals were sacrificed to estimate the degree of liver fibrosis. Isolated Kuppfer cells were treated with GdCl(3) and the expressions of MMPs, MAP kinase activity (ERK, SAPK/JNK, P38) as well as apoptosis were also examined. Rats that received DMN for 4 weeks followed by GdCl(3) injection for 4 weeks showed an reduced liver hydroxyproline content compared to rats treated with DEN followed by saline (277 +/- 22 VS 348 +/- 34 microg/g, n = 6 each, P < 0.01). There were significantly increased MMP-13 mRNA levels in GdCl(3)-treated rats. However, no significant change was observed in procollagen type I mRNA levels. Isolated Kuppfer cells treated with GdCl(3) showed increased MAP kinase activity, especially P38 pathway as well as MMP-13, 9 mRNA and type I collagen-degrading activity leading to apoptosis. SB203580, inhibitor of P38 pathway diminished these activation and prevented apoptosis. These results suggest that Kuppfer cells can reverse liver fibrosis via the expression of MMPs mainly through P38 pathway.

Intrasplenic transplantation of syngenic hepatocytes modified by IFN-gamma gene ameliorates hepatic fibrosis in rats

Transplanted hepatocytes are ideal carriers for exogenous genes in liver gene therapy. The present study investigated the anti-fibrogenic effects of intrasplenically transplanted hepatocytes modified with interferon gamma (IFN-gamma) gene on cirrhotic rats. Hepatocytes isolated from normal Sprague-Dawley (SD) rats were transfected with an adenoviral vector encoding human IFN-gamma gene (AdCMVhIFN-gamma) and transplanted into the spleens of syngenic recipients with ongoing liver fibrosis induced by carbon tetrachloride (CCl(4)). Histology was assessed, and liver hydroxyproline was detected. Additionally, serum procollagen type III (PIIINP) levels and hepatic collagenase activity were measured to determine hepatic collagen synthesis and degradation. Transplantation with AdCMVhIFN-gamma transfected hepatocytes ameliorated the histological outcome of liver fibrosis by reducing liver collagen content and decreasing hepatic hydroxyproline. Additionally, IFN-gamma transfected hepatocytes reduced serum PIIINP levels and increased hepatic collagenase activity. Our data suggest that transplantation of IFN-gamma transfected hepatocytes may reduce the pace of liver fibrosis by inhibiting the synthesis and enhancing the degradation of hepatic collagen.

Prevention of rat hepatic fibrosis by the protease inhibitor, camostat mesilate, via reduced generation of active TGF-beta

BACKGROUND & AIMS

Proteolytic release and activation of latent transforming growth factor beta (TGF-beta) by the hepatic stellate cells (HSCs) are key events for pathogenesis of hepatic fibrosis, and protease inhibitors suppress TGF-beta generation by cultured HSCs, suggesting their potential use as antifibrogenic agents. We explored this idea using camostat mesilate, a serine protease inhibitor, to determine its effects and mechanisms of action in vivo.

METHODS

Camostat mesilate was either added to cultured rat HSCs or administered orally to rats during porcine serum treatment, followed by overexpression of urokinase. We measured cellular and hepatic levels of plasmin, TGF-beta, TGF-beta activity, activated HSC markers (increased cell number, morphologic change, and expression of both alpha-smooth muscle actin and collagen(alpha2)[I]), and fibrosis (Azan-staining and quantification of hydroxyproline content).

RESULTS

Camostat mesilate (500 micromol/L) inhibited generation of TGF-beta by suppressing plasmin activity and reduced the activity of TGF-beta, which blocked in vitro activation of HSCs. In the in vivo model, camostat mesilate (1-2 mg/g of diet) markedly attenuated an increase in hepatic plasmin and TGF-beta levels, HSC activation, and hepatic fibrosis without apparent systemic or local side effects, all of which were reverted by restoration of hepatic plasmin activity.

CONCLUSIONS

Camostat mesilate prevents porcine serum-induced rat hepatic fibrosis via a profound reduction in TGF-beta generation.

Inhibition of transforming growth factor beta prevents progression of liver fibrosis and enhances hepatocyte regeneration in dimethylnitrosamine-treated rats

We investigated whether anti-transforming growth factor beta (TGF-beta) molecular intervention can halt the progression of liver fibrosis in rats. To block TGF-beta action in a specific manner, we prepared an adenovirus expressing a truncated type II TGF-beta receptor (AdTbeta-TR), which specifically inhibits TGF-beta signaling as a dominant-negative receptor. We also used an adenovirus expressing bacterial beta-galactosidase (AdLacZ) as a control adenovirus. Rats were treated with dimethylnitrosamine (DMN) for 3 weeks; then, AdTbeta-TR, AdLacZ, or saline was intravenously applied once, followed by an additional 3-week DMN treatment. The ratio between the truncated receptor and the wild-type receptor at the mRNA level was 15 at 1 week and 10 at 3 weeks after gene transfer. Immunohistostaining analysis showed that the truncated receptor was expressed mainly in septal cells including hepatic stellate cells. Liver fibrosis, as assessed by histology, hydroxyproline content, and the serum level of hyaluronic acid, progressed during the additional 3-week DMN treatment. However, in rats infected with AdTbeta-TR, the fibrosis remained at the level seen in rats given DMN for only 3 weeks. All AdTbeta-TR-treated rats remained alive, whereas DMN-treated rats infused with either AdLacZ or saline died of liver dysfunction. In the livers of AdTbeta-TR-treated rats, electron microscopy showed: 1) less accumulation of extracellular matrix proteins in the Disse's spaces; 2) regenerated hepatocytes; and 3) fat droplet-rich "quiescent" hepatic stellate cells. Our results demonstrate that TGF-beta plays a critical role in the progression of liver fibrosis, and suggest that anti-TGF-beta intervention should be therapeutic in already-established fibrotic livers, not only by suppressing fibrosis, but by facilitating hepatocyte regeneration.

Sho-saiko-to: Japanese herbal medicine for protection against hepatic fibrosis and carcinoma

Herbal medicines, which have been used in China for thousands of years, are now being manufactured in Japan, in standardized form in terms of quality and quantities of ingredients. The Chinese herbal medicine Sho-saiko-to is a mixture of seven herbal preparations, which is widely administered in Japan to patients with chronic hepatitis and cirrhosis. In a prospective study, this herbal medicine was found to play a chemopreventive role in the development of hepatocellular carcinoma in cirrhotic patients. However, little is known about the mechanism by which Sho-saiko-to protects against hepatic fibrosis and carcinoma. Several laboratories, including ours, have clearly demonstrated the preventive and therapeutic effects of Sho-saiko-to on experimental hepatic fibrosis, as well as its inhibitory effect on the activation of hepatic stellate cells, which are the major types of collagen-producing cells. We provided evidence that Sho-saiko-to functions as a potent anti-fibrosuppressant via the inhibition of oxidative stress in hepatocytes and hepatic stellate cells and that its active components are baicalin and baicalein. In addition, Sho-saiko-to has anti-carcinogenic properties in that it inhibits chemical hepatocarcinogenesis in animals, acts as a biological response modifier and suppresses the proliferation of hepatoma cells by inducing apoptosis and arrests the cell cycle. Among the active components of Sho-saiko-to, baicalin, baicalein and saikosaponin-a have the ability to inhibit cell proliferation. It should be noted that baicalin and baicalein are flavonoids with chemical structures very similar to silybinin, which shows anti-fibrogenic activities. This may provide valuable information on the search for novel anti-fibrogenic agents.

Enhanced interstitial collagenase (matrix metalloproteinase-13) production of Kupffer cell by gadolinium chloride prevents pig serum-induced rat liver fibrosis

Hepatic fibrosis results from an imbalance between fibrogenesis and fibrolysis in the liver. It remains uninvestigated whether Kupffer cells produce matrix metalloproteinase-13 (MMP-13), which mainly hydrolyzes extracellular matrix (ECM). We sought to determine the role of Kupffer cells in fibrogenesis/fibrolysis. In vivo, we used the rat model of pig serum-induced liver fibrosis. A subset was treated with gadolinium chloride (GdCl(3)), which specifically acts on Kupffer cells. Administration of GdCl(3) remarkably decreased the hydroxyproline content of the liver and increased the expression of MMP-13 mRNA in the liver without a difference in procollagen type I and tissue inhibitors of metalloproteinase-1 (TIMP-1) mRNA expression on Northern blot analysis with the elimination of ED2-positive cells. In vitro, addition of GdCl(3) to isolated Kupffer cells showed increased type I collagen-degrading activity in a dose-dependent manner as well as MMP-13 mRNA expression on Northern blot analysis. It is concluded that Kupffer cells are a major source of MMP-13 and modulation of Kupffer cells by GdCl(3) prevents liver fibrosis with increased expression of MMP-13 mRNA and protein, whereas procollagen type I and TIMP-1 mRNA, which encode two major effectors of fibrogenesis, were unchanged. This is the first report showing that Kupffer cells produce interstitial collagenase (MMP-13) resulting in the reduction of ECM. This discovery may provide new insights into therapy for hepatic fibrosis.

Hepatic stellate cell activation and liver fibrosis are associated with necroinflammatory injury and Th1-like response in chronic hepatitis C

BACKGROUND/AIMS

The involvement of a direct viral cytopathic effect or an immune-mediated mechanism in the progression of hepatic damage in chronic hepatitis C is controversial. The type of immune response is itself a matter of controversy, and histological data are lacking. The aim of this study was to identify the factors associated with the progression of liver injury in 30 HCV/RNA-positive untreated patients with chronic hepatitis.

METHODS

Necroinflammatory and architectural damage were evaluated using Ishak's score. Activated hepatic stellate cells (HSC) were visualized by immunohistochemistry for alpha-smooth muscle actin (alphaSMA) and quantitated by morphometry. Plasma HCV/RNA was evaluated using a competitive RT-PCR method. To study the type of immune response involved in the progression of liver injury, interferon gamma (IFNgamma)-positive cells (as expression of a Th1-like response) were evaluated by immunohistochemistry and quantitated by morphometry.

RESULTS

HSC were mostly detected close to areas of lobular necroinflammation or lining fibrotic septa. The alphaSMA- and Sirius Red-positive parenchyma correlated significantly with necroinflammatory and architectural scores. IFNgamma-positive cells were detected in periportal areas associated with the inflammatory infiltrates and significantly correlated with architectural damage. No relationship was found between the histological features of liver injury and viral load.

CONCLUSIONS

HSC activation and progression of liver injury are unrelated to viral load but associated with a Th1-like response, a plausible target for the treatment of chronic hepatitis C.

Negative modulation of alpha1(I) procollagen gene expression in human skin fibroblasts: transcriptional inhibition by interferon-gamma

Interferon-gamma (IFN-gamma), a multifunctional cytokine produced by activated Th1 lymphocytes, exerts potent effects on the extracellular matrix by regulating fibroblast function. In this study, we examined the modulation of alpha1(I) procollagen gene (COL1A1) expression by recombinant IFN-gamma. The results showed that IFN-gamma stimulated the rapid accumulation of interferon regulated factor (IRF)-1 mRNA, followed by a delayed and dose-dependent inhibition of alpha1(I) procollagen mRNA expression in skin fibroblasts from several different donors. The inhibitory response was abrogated in fibroblasts stably expressing IRF-1 in the antisense orientation. A marked decrease in the amount of heterogeneous nuclear pre-mRNA preceded the inhibition of COL1A1 mRNA expression. In fibroblasts transiently transfected with COL1A1 promoter-chloramphenicol acetyltransferase reporter gene plasmids, IFN-gamma selectively inhibited promoter activity and abrogated its stimulation induced by TGF-beta. The inhibition by IFN-gamma was not due to downregulation of TGF-beta receptor mRNA expression in the fibroblasts or decreased ligand binding to the receptor. IFN-alpha and IFN-beta by themselves had little effect on promoter activity, but IFN-alpha augmented the inhibitory effect of IFN-gamma. Using a series of 5' deletion constructs, a proximal region of the COL1A1 promoter was shown to function as an IFN-gamma response element. This region of the gene harbors overlapping binding sites for transcription factors Sp1, Sp3, and NF-1 but no homologs of previously characterized IFN-gamma response elements. The putative IFN-gamma response region was sufficient to confer inhibition of reporter gene expression by treatment with IFN-gamma. Gel mobility shift analysis showed that two distinct and specific DNA-protein complexes were formed when fibroblast nuclear extracts were incubated with oligonucleotides spanning the IFN-gamma response region. IFN-gamma did not modify the ability of nuclear proteins to bind to this region. The results indicate that IFN-gamma inhibits COL1A1 expression in fibroblasts principally at the level of gene transcription. Inhibition involves IRF-1 and is mediated through a short proximal promoter segment but without an apparent change in promoter occupancy. The findings provide novel insight into the mechanism of IFN-gamma regulation of fibroblast function.

Fibrosis accelerates the development of enzyme-altered lesions in the rat liver

Injection of pig serum into rats twice a week for 8 weeks induced stellate cell activation resulting in liver fibrosis without parenchymal cell injury. Administration of a choline deficient L-amino acid defined (CDAA) diet for 6 weeks with or without pig serum pretreatment led to the development of preneoplastic lesions that were positive for the placental form of glutathione S-transferase (GSTP). Pig serum pretreatment induced more activated stellate cells in the livers of rats subsequently fed a CDAA diet for 6 weeks compared with rats fed the CDAA diet alone. Activated stellate cells were detected as smooth muscle actin (SMA)-positive cells and by the expression of SMA messenger RNA. These cells caused severe fibrosis as assessed by the hepatic hydroxyproline content. Pre-existing fibrosis induced by the activation of stellate cells with pig serum pretreatment increased hepatic malondialdehyde (MDA) level in parallel with GSTP-positive lesions. These results indicate that pre-existing fibrosis with the activated stellate cells accelerates the development of preneoplastic lesions in a CDAA diet model.

Inhibitory effects of the herbal medicine Sho-saiko-to (TJ-9) on cell proliferation and procollagen gene expressions in cultured rat hepatic stellate cells

BACKGROUND/AIMS

It is of extreme importance to prevent liver fibrosis and subsequent progression to liver cirrhosis. The aim of our study was to elucidate in vitro whether Sho-saiko-to exerted inhibitory effects on hepatic stellate cells.

METHODS

Hepatic stellate cells were isolated from male Wistar rats. Water-soluble ingredients of Sho-saiko-to were obtained at concentrations of 10, 100, 250, 500 and 1000 microg/ml. Morphological transformation was observed under a phase-contrast microscope. Flow cytometric analysis was performed on day 4 after culture to evaluate the potential to proliferate of the stellate cells by analyzing cell cycles. Northern blot analysis was carried out on day 3 after culture to determine the expressions of type I and type III procollagen mRNAs.

RESULTS

(i) Sho-saiko-to 500 and 1000 microg/ml inhibited morphological transformation of the stellate cells to myofibroblast-like cells. (ii) Sho-saiko-to 500 and 1000 microg/ml significantly (p<0.0001) accumulated the cells in the G0/G1 phase (118.8+/-0.7%, 119.2+/-0.5%, respectively as compared with control) and significantly (p<0.0001) decreased cell numbers subsequently in G2/M phase (47.5+/-8.1%, 48.9+/-2.0%, respectively). (iii) Sho-saiko-to 500 and 1000 microg/ml also significantly (p<0.05 or p<0.0001) suppressed procollagen mRNA expression of type I to 51.5+/-6.4%, 34.9+/-3.7%, respectively, and type III to 51.3+/-12.3%, 46.7+/-11.4%, respectively.

CONCLUSIONS

We have clarified the inhibitory effects of Sho-saiko-to on hepatic stellate cells in vitro. Sho-saiko-to could be a potent inhibitor in the pathogenesis of liver fibrosis.