Dynamic change of cells expressing MMP-2 mRNA and MT1-MMP mRNA in the recovery from liver fibrosis in the rat

Rosavin Ameliorates Hepatic Inflammation and Fibrosis in the NASH Rat Model via Targeting Hepatic Cell Death

Background: Non-alcoholic fatty liver disease (NAFLD) represents the most common form of chronic liver disease that urgently needs effective therapy. Rosavin, a major constituent of the Rhodiola Rosea plant of the family Crassulaceae, is believed to exhibit multiple pharmacological effects on diverse diseases. However, its effect on non-alcoholic steatohepatitis (NASH), the progressive form of NAFLD, and the underlying mechanisms are not fully illustrated. Aim: Investigate the pharmacological activity and potential mechanism of rosavin treatment on NASH management via targeting hepatic cell death-related (HSPD1/TNF/MMP14/ITGB1) mRNAs and their upstream noncoding RNA regulators (miRNA-6881-5P and lnc-SPARCL1-1:2) in NASH rats. Results: High sucrose high fat (HSHF) diet-induced NASH rats were treated with different concentrations of rosavin (10, 20, and 30 mg/kg/day) for the last four weeks of dietary manipulation. The data revealed that rosavin had the ability to modulate the expression of the hepatic cell death-related RNA panel through the upregulation of both (HSPD1/TNF/MMP14/ITGB1) mRNAs and their epigenetic regulators (miRNA-6881-5P and lnc-SPARCL1-1:2). Moreover, rosavin ameliorated the deterioration in both liver functions and lipid profile, and thereby improved the hepatic inflammation, fibrosis, and apoptosis, as evidenced by the decreased protein levels of IL6, TNF-α, and caspase-3 in liver sections of treated animals compared to the untreated NASH rats. Conclusion: Rosavin has demonstrated a potential ability to attenuate disease progression and inhibit hepatic cell death in the NASH animal model. The produced effect was correlated with upregulation of the hepatic cell death-related (HSPD1, TNF, MMP14, and ITGB1) mRNAs—(miRNA-6881-5P—(lnc-SPARCL1-1:2) RNA panel.

Long noncoding RNA GAS5 inhibits LX-2 cells activation by suppressing NF-κB signalling through regulation of the miR-433-3p/TLR10 axis

BACKGROUND

Liver fibrosis is a common disease that can lead to hepatic failure.

AIMS

Our aims were to reveal the role of GAS5 in the regulation of liver fibrosis.

METHODS

LX-2 human hepatic satellite cells (HSCs) were cultured and activated using TGF-β1 treatment. A CCK-8 assay was performed to assess cell viability. A luciferase assay was employed to monitor the interactions between miR-433-3p and GAS5 or toll-like receptor 10 (TLR10). Western blotting and real-time quantitative PCR (RT-qPCR) were applied to detect the expression levels of α-SMA, Col. I, PCNA-, MMP2-, MMP9-, TLR10-, and NF-κB-related molecules at the protein and RNA levels.

RESULTS

GAS5 and TLR10 were decreased while miR-433-3p was upregulated in TGF-β1-activated LX-2 cells. Upregulation of GAS5 or downregulation of miR-433-3p suppressed HSC activation, and luciferase assays indicated that miR-433-3p binds with GAS5 and the 3'-UTR of TLR10. MiR-433-3p upregulation and TLR10 downregulation rescued the impacts of GAS5 overexpression or miR-433-3p knockdown on LX-2 cells. Upregulation of GAS5 also suppressed the phosphorylation of NF-κB through the miR-433-3p/TLR10 axis.

CONCLUSION

LncRNA GAS5 exerts an inhibitory effect on HSC activation by suppressing NF-κB signalling through regulation of the miR-433-3p/TLR10 axis.

Clinical Significance of HSPD1/MMP14/ITGB1/miR-6881-5P/Lnc-SPARCL1-1:2 RNA Panel in NAFLD/NASH Diagnosis: Egyptian Pilot Study

Background: Non-alcoholic steatohepatitis ((NASH) is the progressive form of (non-alcoholic fatty liver disease) (NAFLD), which can progress to liver cirrhosis and hepatocellular carcinoma. There is no available reliable non-invasive diagnostic tool to diagnose NASH, and still the liver biopsy is the gold standard in diagnosis. In this pilot study, we aimed to evaluate the Nod-like receptor (NLR) signaling pathway related RNA panel in the diagnosis of NASH. Methods: Bioinformatics analysis was done, with retrieval of the HSPD1/MMP14/ITGB1/miR-6881-5P/Lnc-SPARCL1-1:2 RNA panel based on the relation to the NLR-signaling pathway. Hepatitis serum markers, lipid profile, NAFLD score and fibrosis score were assessed in the patients’ sera. Reverse transcriptase real time polymerase chain reaction (RT-PCR) was done to assess the relative expression of the RNA panel among patients who had NAFLD without steatosis, NAFLD with simple steatosis, NASH and healthy controls. Results: We observed up-regulation of Lnc-SPARCL1-1:2 lncRNA that led to upregulation of miR-6881-5P with a subsequent increase in levels of HSPD1, MMP14, and ITGB1 mRNAs. In addition, ROC curve analysis was done, with discriminative cutoff values that aided discrimination between NASH cases and control, and also between NAFLD, simple steatosis and NASH. Conclusion: This pilot study concluded that HSPD1/MMP14/ITGB1/miR-6881-5P/Lnc-SPARCL1-1:2 panel expression has potential in the diagnosis of NASH, and also differentiation between NAFLD, simple steatosis and NASH cases.

Secreted matrix metalloproteinase-14 is a predictor for antifibrotic effect of IC-2-engineered mesenchymal stem cell sheets on liver fibrosis in mice

Introduction

Transplantation of IC-2-engineered bone marrow-derived mesenchymal stem cell (BM-MSC) sheets (IC-2 sheets) was previously reported to potentially reduce liver fibrosis.

Methods

This study prepared IC-2-engineered cell sheets from multiple lots of BM-MSCs and examined the therapeutic effects of these cell sheets on liver fibrosis induced by carbon tetrachloride in mice. The predictive factors for antifibrotic effect on liver fibrosis were tried to identify in advance.

Results

Secreted matrix metalloproteinase (MMP)-14 was found to be a useful predictive factor to reduce liver fibrosis. Moreover, the cutoff index of MMP-14 for 30% reduction of liver fibrosis was 0.918 fg/cell, judging from univariate analysis and receiver operating curve analysis. In addition, MMP-13 activity and thioredoxin contents in IC-2 sheets were also inversely correlated with hepatic hydroxyproline contents. Finally, IC-2 was also found to promote MMP-14 secretion from BM-MSCs of elderly patients. Surprisingly, the values of secreted MMP-14 from BM-MSCs of elderly patients were much higher than those of young persons.

Conclusion

The results of this study suggest that the IC-2 sheets would be applicable to clinical use in autologous transplantation for patients with cirrhosis regardless of the patient's age.

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IC-2- sheets from multiple lots of BM-MSCs ameliorate liver fibrosis in mice.

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Secreted MMP-14 is a useful predictive marker to reduce liver fibrosis.

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MMP-13 and thioredoxin in IC-2 sheets were also associated with liver fibrosis.

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IC-2 also promotes MMP-14 secretion from BM-MSCs of elderly patients.

Enhancement of Silymarin Anti-fibrotic Effects by Complexation With Hydroxypropyl (HPBCD) and Randomly Methylated (RAMEB) β-Cyclodextrins in a Mouse Model of Liver Fibrosis

Silymarin (Sy) shows limited water solubility and poor oral bioavailability. Water-soluble hydroxypropyl (HPBCD) and randomly methylated (RAMEB) β-cyclodextrins were designed to enhance anti-fibrotic efficiency of silymarin in CCl₄-induced liver fibrosis in mice. Experimental fibrosis was induced by intraperitoneal injection with 2 ml/kg CCl₄ (20% v/v) twice a week, for 7 weeks. Mice were orally treated with 50 mg/kg of Sy-HPBCD, Sy-RAMEB and free silymarin. For assessment of the spontaneous reversion of fibrosis, CCl₄ treated animals were investigated after 2 weeks of recovery time. The CCl₄ administration increased hepatic oxidative stress, augmented the expression of transforming growth factor-β1 (TGF-β1) and Smad 2/3, and decreased Smad 7 expression. Furthermore, increased α-smooth muscle actin (α-SMA) expression indicated activation of hepatic stellate cells (HSCs), while up-regulation of collagen I (Col I) and matrix metalloproteinases (MMPs) expression led to an altered extracellular matrix enriched in collagen, confirmed as well by trichrome staining and electron microscopy analysis. Treatment with Sy-HPBCD and Sy-RAMEB significantly reduced liver injury, attenuating oxidative stress, restoring antioxidant balance in the hepatic tissue, and significantly decreasing collagen deposits in the liver. The levels of pro-fibrogenic markers' expression were also significantly down-regulated, whereas in the group for spontaneous regression of fibrosis, they remained significantly higher, even at 2 weeks after CCl₄ administration was discontinued. The recovery was significantly lower for free silymarin group compared to silymarin/β cyclodextrins co-treatments. Sy-HPBCD was found to be the most potent anti-fibrotic complex. We demonstrated that Sy-HPBCD and Sy-RAMEB complexes decreased extracellular matrix accumulation by inhibiting HSC activation and diminished the oxidative damage. This might occur via the inhibition of TGF-β1/Smad signal transduction and MMP/tissue inhibitor of MMPs (TIMP) rebalance, by blocking the synthesis of Col I and decreasing collagen deposition. These results suggest that complexation of silymarin with HPBCD or RAMEB represent viable options for the its oral delivery, of the flavonoid as a potential therapeutic entity candidate, with applications in the treatment of liver fibrosis.

Matrix metalloproteinase functions in hepatic injury and fibrosis

Liver fibrosis is the most common final outcome for chronic liver diseases. The complex pathogenesis includes hepatic parenchymal damage as a result of a persistent noxe, activation and recruitment of immune cells, activation of hepatic stellate cells, and the synthesis of fibrotic extracellular matrix (ECM) components leading to scar formation. Clinical studies and animal models demonstrated that fibrosis can be reversible. In this regard matrix metalloproteinases (MMPs) have been focused as therapeutic targets due to their ability to modulate tissue turnover during fibrogenesis as well as regeneration and, of special interest, due to their influence on cellular behavior like proliferation, gene expression, and apoptosis that, in turn, impact fibrosis and regeneration. The current review aims to summarize and update the knowledge about expression pattern and the central roles of MMPs in hepatic fibrosis.

Mice deficient in N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase exhibit enhanced liver fibrosis and delayed recovery from fibrosis in carbon tetrachloride-treated mice

Background

Chondroitin/dermatan sulfate (CS/DS) rich in N-acetylgalactosamine 4,6-bissulfate (GalNAc(4,6SO₄)) residues is present as decorin and/or biglycan in mouse liver, and GalNAc(4,6SO₄) residues disappeared completely in N-acetylgalactosamine 4-sulfate 6-O-sulfotransferase (GalNAc4S-6ST) knockout (KO) mice. The aim of this study was to investigate whether CS/DS rich in GalNAc(4,6SO₄) residues participate in the progression or resolution of liver fibrosis.

Methods

Wild type (WT) and GalNAc4S-6ST KO mice were treated with CCl₄ for 5 weeks. After discontinuation of CCl₄ administration, histochemical and biochemical changes and expression of genes related to matrix components were compared between WT and GalNAc4S-6ST KO mice.

Results and conclusion

On 2 days after cessation of CCl₄ administration, higher fibrosis was observed in KO mice than in WT mice by Sirius Red staining. Serum alanine aminotransferase activity was higher in KO mice than in WT mice. Hydroxyproline contents and Sirius Red staining showed that repair of liver fibrosis in the recovery stages appeared to be delayed in KO mice. Expression of mRNA of matrix metalloproteinase (MMP)-2, MMP-13 and versican peaked at 2 days after cessation of CCl₄ administration and was higher in KO mice than in WT mice. Expression of MMP-9 in the recovery stage was lower in KO mice than in WT mice. Our findings demonstrate that defect in GalNAc4S-6ST, which resulted in disappearance of CS/DS containing GalNAc(4,6SO₄), appear to contribute to progression of liver fibrosis, delayed recovery from fibrosis, and various changes in the expression of proteoglycans and MMPs in carbon tetrachloride–treated mice.

Curcumin targets multiple pathways to halt hepatic stellate cell activation: updated mechanisms in vitro and in vivo

Nonalcoholic steatohepatitis (NASH) is the advanced form of nonalcoholic fatty liver disease, which is often accompanied by obese and/or type II diabetes mellitus. Approximately one-third of NASH patients develop hepatic fibrosis. Hepatic stellate cells are the major effector cells during liver fibrogenesis. Advanced liver fibrosis usually proceeds to cirrhosis and even hepatocellular carcinoma, leading to liver failure, portal hypertension and even death. Currently, there are no approved agents for treatment and prevention of liver fibrosis in human beings. Curcumin, the principal curcuminoid of turmeric, has been reported to show antitumor, antioxidant, and anti-inflammatory properties both in in vitro and in vivo systems. Accumulating data shows that curcumin plays a critical role in combating liver fibrogenesis. This review will discuss the inhibitory roles of curcumin and update the underlying mechanisms by which curcumin targets in inhibiting hepatic stellate cell activation.

Hepatocyte produced matrix metalloproteinases are regulated by CD147 in liver fibrogenesis

BACKGROUND

The classical paradigm of liver injury asserts that hepatic stellate cells (HSC) produce, remodel and turnover the abnormal extracellular matrix (ECM) of fibrosis via matrix metalloproteinases (MMPs). In extrahepatic tissues MMP production is regulated by a number of mechanisms including expression of the glycoprotein CD147. Previously, we have shown that CD147 is expressed on hepatocytes but not within the fibrotic septa in cirrhosis [1]. Therefore, we investigated if hepatocytes produce MMPs, regulated by CD147, which are capable of remodelling fibrotic ECM independent of the HSC.

METHODS

Non-diseased, fibrotic and cirrhotic livers were examined for MMP activity and markers of fibrosis in humans and mice. CD147 expression and MMP activity were co-localised by in-situ zymography. The role of CD147 was studied in-vitro with siRNA to CD147 in hepatocytes and in-vivo in mice with CCl4 induced liver injury using ãCD147 antibody intervention.

RESULTS

In liver fibrosis in both human and mouse tissue MMP expression and activity (MMP-2, -9, -13 and -14) increased with progressive injury and localised to hepatocytes. Additionally, as expected, MMPs were abundantly expressed by activated HSC. Further, with progressive fibrosis there was expression of CD147, which localised to hepatocytes but not to HSC. Functionally significant in-vitro regulation of hepatocyte MMP production by CD147 was demonstrated using siRNA to CD147 that decreased hepatocyte MMP-2 and -9 expression/activity. Further, in-vivo α-CD147 antibody intervention decreased liver MMP-2, -9, -13, -14, TGF-β and α-SMA expression in CCl4 treated mice compared to controls.

CONCLUSION

We have shown that hepatocytes produce active MMPs and that the glycoprotein CD147 regulates hepatocyte MMP expression. Targeting CD147 regulates hepatocyte MMP production both in-vitro and in-vivo, with the net result being reduced fibrotic matrix turnover in-vivo. Therefore, CD147 regulation of hepatocyte MMP is a novel pathway that could be targeted by future anti-fibrogenic agents.

Fibrogenesis and Carcinogenesis in Nonalcoholic Steatohepatitis (NASH): Involvement of Matrix Metalloproteinases (MMPs) and Tissue Inhibitors of Metalloproteinase (TIMPs)

Nonalcoholic steatohepatitis (NASH) is emerging worldwide because life-styles have changed to include much over-eating and less physical activity. The clinical and pathophysiological features of NASH are very different from those of HBV- and HCV-chronic liver diseases. The prognosis of NASH is worse among those with nonalcoholic fatty liver diseases (NAFLD), and some NASH patients show HCC with or without cirrhosis. In the present review we discuss fibrogenesis and the relationship between fibrosis and HCC occurrence in NASH to clarify the role of MMPs and TIMPs in both mechanisms. Previously we proposed MMP and TIMP expression in the multi-step occurrence of HCC from the literature based on viral-derived HCC. We introduce again these expressions during hepatocarcinogenesis and compare them to those in NASH-derived HCC, although the relationship with hepatic stem/progenitor cells (HPCs) invasion remains unknown. Signal transduction of MMPs and TIMPs is also discussed because it is valuable for the prevention and treatment of NASH and NASH-derived HCC.

MMP-14 is necessary but not sufficient for invasion of three-dimensional collagen by human muscle satellite cells

The twenty-five known matrix metalloproteases (MMPs) and their endogenous inhibitors, tissue inhibitors of metalloproteases (TIMPs), mediate cell invasion through the extracellular matrix (ECM). In a comparative three-dimensional assay, we analyzed human and mouse satellite cells' competence to invade an artificial ECM (collagen I). We identified a single MMP that 1) is expressed by human muscle satellite cells; 2) is induced at the mRNA/protein level by adhesion to collagen I; and 3) is necessary for invasion into a collagen I matrix. Interestingly, murine satellite cells neither express this MMP, nor invade the collagen matrix. However, exogenous human MMP-14 is not sufficient to induce invasion of a collagen matrix by murine cells, emphasizing species differences.

Resolution of liver fibrosis by isoquinoline alkaloid berberine in CCl₄-intoxicated mice is mediated by suppression of oxidative stress and upregulation of MMP-2 expression

Liver fibrosis is the result of chronic liver injury, and it represents a widespread medical problem. The aim of this study is to investigate the antifibrotic activity of isoquinoline alkaloid berberine in carbon tetrachloride (CCl₄)-induced damage in mice. Hepatic fibrosis was induced by intraperitoneal (i.p.) administration of CCl₄ (2 mL/kg, 20% v/v in olive oil) twice a week for 8 weeks. Berberine at the doses of 3 and 9 mg/kg and silymarin at the dose of 50 mg/kg were given i.p. once daily for the next 2 weeks. CCl₄ intoxication increased the levels of serum transaminases and induced oxidative stress in the liver. Hepatic fibrosis was evidenced by a massive deposition of collagen, which coincided with increased expression of tumor necrosis factor (TNF)-α and transforming growth factor (TGF)-β1 and the activation of hepatic stellate cells. The high-dose berberine (9 mg/kg) ameliorated oxidative stress, decreased TNF-α and TGF-β1 expression, increased the levels of matrix metalloproteinase (MMP)-2, and stimulated the elimination of fibrous deposits. Berberine at the dose of 9 mg/kg exhibited stronger therapeutic activity against hepatic fibrosis than silymarin at the dose of 50 mg/kg. In vitro analyses show an important scavenging activity of berberine against oxygen and nitrogen reactive species. The results of this study suggest that berberine could ameliorate liver fibrosis through the suppression of hepatic oxidative stress and fibrogenic potential, concomitantly stimulating the degradation of collagen deposits by MMP-2.

Butyrate-producing probiotics reduce nonalcoholic fatty liver disease progression in rats: new insight into the probiotics for the gut-liver axis

Nonalcoholic fatty liver disease (NAFLD) includes simple steatosis, nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. The gut-derived endotoxin plays an essential role in the pathophysiological development and progression of NAFLD. By using rat models of choline-deficient/L-amino acid-defined (CDAA)-diet-induced NAFLD, we examined whether MIYAIRI 588–a butyrate-producing probiotic – prevents the progression of pathophysiological changes from steatosis to hepatocarcinogenesis. In vivo experiments showed that treatment with MIYAIRI 588 reduced CDAA-diet-induced hepatic lipid deposition and significantly improved the triglyceride content, insulin resistance, serum endotoxin levels, and hepatic inflammatory indexes. We also found that MIYAIRI 588 substantially increased the activation of hepatic adenosine 5′-monophosphate-activated protein kinase (AMPK) and AKT and the expression of lipogenesis- or lipolysis-related proteins. MIYAIRI 588 also improved CDAA-diet-induced delocalization and substantially decreased the expression of the tight-junction proteins intestinal zonula occluden-1 and occludin in CDAA-diet-fed rats. Further, the MIYAIRI 588-treated rats also showed remarkable induction of nuclear factor erythoid 2-related factor 2 (Nrf2) and its targeted antioxidative enzymes, which suppressed hepatic oxidative stress. In vitro studies revealed that treatment with sodium butyrate (NaB) also activated AMPK and AKT and enhanced Nrf2 expression by precluding ubiquitination, thereby increasing the half-life of the Nrf2 protein. Pharmacological studies and siRNA knockdown experiments showed that NaB-mediated AMPK activation induced the phosphorylation and nuclear translocation of Sirtuin 1, leading to the increased assembly of mammalian TOR complex 2 and phosphorylation of AKT at Ser473 and subsequent induction of Nrf2 expression and activation. These favorable changes caused an obvious decrease in hepatic fibrous deposition, GST-P-positive foci development, and hepatocarcinogenesis. Our data clearly established that the probiotic MIYAIRI 588 has beneficial effects in the prevention of NAFLD progression.

Metallothionein gene transfection reverses the phenotype of activated human hepatic stellate cells

Metallothionein (MT) gene therapy leads to resolution of liver fibrosis in mouse model. The present study was undertaken to test the hypothesis that reversal of the phenotype of activated hepatic stellate cells (HSCs) contributes to the fibrinolysis effect of MT. Human HSC LX-2 cells were activated after they were cultured for 24 hours, as indicated by expression of α-smooth muscle actin (α-SMA) and collagen-I and depressed expression of collagenases. Transfection with a plasmid containing human MT-IIA gene in the activated HSCs effectively increased the protein level of MT. The expression of MT was accompanied by the reduction in protein levels of α-SMA and collagen-I and a decrease in their mRNA levels. Of importance, MT gene transfection resulted in upregulation of matrix metalloproteinases 1, 8, and 13, which are involved in the resolution of liver fibrosis. This study demonstrates that reversal of the phenotype of activated HSCs, particularly the upregulation of collagenases, is likely to be involved in the resolution of liver fibrosis observed in MT gene therapy.

Mechanistic overview of reactive species-induced degradation of the endothelial glycocalyx during hepatic ischemia/reperfusion injury

Endothelial cells are covered by a delicate meshwork of glycoproteins known as the glycocalyx. Under normophysiological conditions the glycocalyx plays an active role in maintaining vascular homeostasis by deterring primary and secondary hemostasis and leukocyte adhesion and by regulating vascular permeability and tone. During (micro)vascular oxidative and nitrosative stress, which prevails in numerous metabolic (diabetes), vascular (atherosclerosis, hypertension), and surgical (ischemia/reperfusion injury, trauma) disease states, the glycocalyx is oxidatively and nitrosatively modified and degraded, which culminates in an exacerbation of the underlying pathology. Consequently, glycocalyx degradation due to oxidative/nitrosative stress has far-reaching clinical implications. In this review the molecular mechanisms of reactive oxygen and nitrogen species-induced destruction of the endothelial glycocalyx are addressed in the context of hepatic ischemia/reperfusion injury as a model disease state. Specifically, the review focuses on (i) the mechanisms of glycocalyx degradation during hepatic ischemia/reperfusion, (ii) the molecular and cellular players involved in the degradation process, and (iii) its implications for hepatic pathophysiology. These topics are projected against a background of liver anatomy, glycocalyx function and structure, and the biology/biochemistry and the sources/targets of reactive oxygen and nitrogen species. The majority of the glycocalyx-related mechanisms elucidated for hepatic ischemia/reperfusion are extrapolatable to the other aforementioned disease states.

Interferon α-2a reduces carbon tetrachloride-induced hepatic fibrosis in rats

AIM: To observe the effect of IFNα-2a on liver fibrosis induced with carbon tetrachloride (CCl₄) in rats.

METHODS: Fifty female Sprague-Dawley rats were equally and randomly into five groups: groups A, B, C, D and E. Liver fibrosis was induced in rats of groups B, C and D with CCl₄. Group A was treated with normal saline, while groups C, D and E were treated with 60 000, 120 000 and 60 000 U/kg IFNα-2a, respectively. At week 8, blood and liver tissue samples were collected to measure liver function (ALT, AST, TBIL, TP), evaluate liver fibrosis (HA, LN, PCIII) and pathological changes (HE staining, masson staining and reticular fiber staining).

RESULTS: Hepatic fibrosis was successfully induced by CCl₄ injection, and significant fibrosis around the portal area and formation of spiky fibers and fibrous septa were observed. Serum levels of ALT, AST, TBiL, HA and LN levels were significantly higher in groups B, C and D than in group A (F = 14.8, 4.4, 7.8, 51.3, 68.9; all P < 0.05). Serum levels of ALT, AST and TBiL were significantly lower in groups C and D than in group B, and in group D than in group C.

CONCLUSION: IFNα-2a reduces CCl₄-induced liver fibrosis in a dose-dependent manner in rats.

Matrix metalloproteinase-13 promotes recovery from experimental liver cirrhosis in rats

OBJECTIVE

To evaluate the role of matrix metalloproteinase (MMP)-13 gene expression in the early phase of recovery from liver fibrosis/cirrhosis.

METHODS

Liver fibrosis was induced in male Wistar rats by administration of carbon tetrachloride (CCl(4)) for 10 weeks. Recombinant adenovirus-mediated human MMP-13 gene transfer (RAdMMP-13) was performed via the femoral vein on day 3 after the last CCl(4) injection. The role of MMP-13 in stably expressing cell lines was also analyzed.

RESULTS

Fibrous deposition in the liver was decreased in RAdMMP-13-injected rats by day 3 after gene transfer compared with empty vector RAd66-injected rats. Furthermore, MMP-2 and MMP-9 enzymatic activity was markedly enhanced in the liver of RAdMMP-13 injected rats. Hepatocyte growth factor (HGF) induction was also increased in RAdMMP-13 injected rats. In established stable HT-1080 cells transfected with MMP-13, HGF-α expression and MMP-2 and MMP-9 enzymatic activity were increased. The conversion of precursor HGF into mature HGF was also increased in the MMP-13 expressing cell lines.

CONCLUSION

Forced MMP-13 expression effectively accelerated recovery from liver cirrhosis via the effects of MMP-13-mediated HGF, MMP-2, and MMP-9 expression, which induced the degradation of collagen fibers and promoted hepatic regeneration.

Regression of allograft airway fibrosis: the role of MMP-dependent tissue remodeling in obliterative bronchiolitis after lung transplantation

Obliterative bronchiolitis after lung transplantation is a chronic inflammatory and fibrotic condition of small airways. The fibrosis associated with obliterative bronchiolitis might be reversible. Matrix metalloproteinases (MMPs) participate in inflammation and tissue remodeling. MMP-2 localized to myofibroblasts in post-transplant human obliterative bronchiolitis lesions and to allograft fibrosis in a rat intrapulmonary tracheal transplant model. Small numbers of infiltrating T cells were also observed within the fibrosis. To modulate inflammation and tissue remodeling, the broad-spectrum MMP inhibitor SC080 was administered after the allograft was obliterated, starting at post-transplant day 21. The allograft lumen remained obliterated after treatment. Only low-dose (2.5 mg/kg per day) SC080 significantly reduced collagen deposition, reduced the number of myofibroblasts and the infiltration of T cells in association with increased collagenolytic activity, increased MMP-2 gene expression, and decreased MMP-8, MMP-9, and MMP-13 gene expression. In in vitro experiments using cultured myofibroblasts, a relatively low concentration of SC080 increased MMP-2 activity and degradation of type I collagen. Moreover, coculture with T cells facilitated persistence of myofibroblasts, suggesting a role for T-cell infiltration in myofibroblast persistence in fibrosis. By combining low-dose SC080 with cyclosporine in vivo at post-transplant day 28, partial reversal of obliterative fibrosis was observed at day 42. Thus, modulating MMP activity might reverse established allograft airway fibrosis by regulating inflammation and tissue remodeling.

Increased susceptibility to liver fibrosis with age is correlated with an altered inflammatory response

It has been suggested that increasing age is correlated with an acceleration of the progression of liver fibrosis induced by various agents, such as hepatitis C virus or chronic alcohol consumption. However, the cellular and molecular changes underlying this predisposition are not entirely understood. In the context of an aging population, it becomes challenging to decipher the mechanisms responsible for this higher susceptibility of older individuals to this acquired liver disorder. To address this issue, we induced liver fibrosis by carbon tetrachloride (CCl(4)) chronic administration to 8-week- and 15-month-old mice. We confirmed that susceptibility to fibrosis development increased with age and showed that aging did not affect fibrosis resolution capacity. We then focused on the impairment of hepatocyte proliferation, oxidative stress, and inflammation as potential mechanisms accelerating the development of fibrosis in the elderly. We detected no inhibition of hepatocyte proliferation after CCl(4) injury in 15-month-old mice, whereas it was inhibited after a partial hepatectomy. Finally, we observed that, in a context in which liver oxidative stress was not differentially increased in both experimental groups, there was a higher recruitment of inflammatory cells, including mostly macrophages and lymphocytes, oriented toward a T helper 2 (T(H)2) response in older mice. Our data show that in conditions of equivalent levels of oxidative stress and maintained hepatocyte proliferative capacity, an increased inflammatory reaction mainly composed of CD4(+) lymphocytes and macrophages expressing T(H)2 cytokines is the main factor involved in the higher susceptibility to fibrosis with increasing age.

An orally available small imidazolium salt ameliorates inflammation and fibrosis in a murine model of cholestasis

Hepatic fibrosis is the result of chronic liver injuries underlined by diverse etiologies. The massive accumulation of extracellular matrix (ECM) proteins during fibrogenesis leads to structural distortion and functional disruption of the liver. There is currently no effective standard treatment for liver fibrosis. We previously identified a class of imidazolium salts (IMSs) with anti-fibrotic properties in a cell-based screen. In this report, we investigated the anti-fibrotic efficacy and mechanisms of a small IMS, 1,3-diisopropylimidazolium tetrafluoroborate (DPIM), in a hepatic fibrosis model induced by bile duct ligation (BDL) in mice. The orally available DPIM was administered to BDL mice via drinking water at three concentrations (0.5, 0.75, and 1 g/l) for 4 weeks. We observed a significant reduction in inflammation and collagen deposition in the liver, which could be mediated by a reduction in the expression of monocyte chemoattractant protein-1 (MCP-1) and by an enhancement in the matrix metalloproteinase-mediated ECM remodeling. The current findings highlight the importance for simultaneously targeting multiple pathways to more effectively attenuate and resolve liver fibrosis and warrant further studies on this compound in additional models of hepatic fibrosis.

Cholestatic liver fibrosis and toxin-induced fibrosis are exacerbated in matrix metalloproteinase-2 deficient mice

Matrix metalloproteinase (MMP) plays an important role in homeostatic regulation of the extracellular environment and degradation of matrix. During liver fibrosis, several MMPs, including MMP-2, are up-regulated in activated hepatic stellate cells, which are responsible for exacerbation of liver cirrhosis. However, it remains unclear how loss of MMP-2 influences molecular dynamics associated with fibrogenesis in the liver. To explore the role of MMP-2 in hepatic fibrogenesis, we employed two fibrosis models in mice; toxin (carbon tetrachloride, CCl4)-induced and cholestasis-induced fibrosis. In the chronic CCl4 administration model, MMP-2 deficient mice exhibited extensive liver fibrosis as compared with wild-type mice. Several molecules related to activation of hepatic stellate cells were up-regulated in MMP-2 deficient liver, suggesting that myofibroblastic change of hepatic stellate cells was promoted in MMP-2 deficient liver. In the cholestasis model, fibrosis in MMP-2 deficient liver was also accelerated as compared with wild type liver. Production of tissue inhibitor of metalloproteinase 1 increased in MMP-2 deficient liver in both models, while transforming growth factor β, platelet-derived growth factor receptor and MMP-14 were up-regulated only in the CCl4 model. Our study demonstrated, using 2 experimental murine models, that loss of MMP-2 exacerbates liver fibrosis, and suggested that MMP-2 suppresses tissue inhibitor of metalloproteinase 1 up-regulation during liver fibrosis.

Hydroxyproline-containing collagen analogs trigger the release and activation of collagen-sequestered proMMP-2 by competition with prodomain-derived peptide P33-42

Background

Fibrolytic and profibrotic activities of the matrix metalloproteinases (MMPs)-2 and -9 play a central role in liver fibrosis. Since binding to the extracellular matrix influences the activity of both gelatinases, here the role of fibrillar collagens as the most abundant matrix components in fibrotic tissue was investigated.

Results

In situ zymography and immunohistology showed association of enzymatically inactive prodomain-containing proMMP-2 and proMMP-9 but not of their activated forms to fibrillar collagen structures, which are not substrates of these gelatinases. In solid-phase binding studies with human collagens and collagen fragments, up to 45% of [¹²⁵I]-labeled proMMP-2 and proMMP-9 but not of active (act)MMP-2 and actMMP-9 were retained by natural collagenous molecules and by synthetic analogs containing repeated Gly-Pro-Hyp triplets (GPO). Surface plasmon resonance yielded binding constants for the interaction of collagen type I (CI) with proMMP-2 and proMMP-9 in a nanomolar range. Values for actMMP-2 and actMMP-9 were 30-40 times higher. Tenfold molar excesses of (GPO)₁₀ reduced the interaction of CI with pro- and actMMP-2 by 22- or 380-fold and resulted in prodomain release accompanied by high enzymatic activation and activity. Pointing to gelatine substrate displacement, higher (GPO)₁₀ concentrations blocked the enzymatic activity. The MMP-2 prodomain-derived collagen-binding domain peptide (P_33-42) binds to the collagen-binding domain of MMP-2, thereby preserving enzymatic inactivity. Synthetic P_33-42 peptide competed with proMMP-2 binding to CI and prevented (GPO)₁₀-mediated proMMP-2 activation. In contrast to (GPO)₁₀, P_33-42 did not activate proMMP-2, making triple helical and hydroxyproline-containing (GPO)₁₀ unique in modulating gelatinase availability and activity.

Conclusions

These findings suggest novel strategies using collagen analogs for the resolution of liver fibrosis via fibrotic matrix-sequestered gelatinases.

Short interfering RNA targetting NF-kappa B induces apoptosis of hepatic stellate cells and attenuates extracellular matrix production

BACKGROUND

Pharmacological inhibition of the NF-κB activity enhances hepatic stellate cell apoptosis and reverses experimental fibrosis. However, there is no report on the effects of NF-κB knockdown on apoptosis and extracellular matrix secretion in hepatic stellate cells. The aim of the present study is to explore the effects of siRNA targetting NF-κB on the apoptosis and extracellular matrix production in hepatic stellate cells.

METHODS

The immortalised hepatic stellate cell line HSC-T6 was transfected with siRNA; 72h later, cells were stimulated by LPS for 1h; these cells were collected for further use. Hepatic stellate cell apoptosis was determined by fluorescence activated cell sorter analysis, TUNEL assay and caspase-3 activity measurement. Matrix metalloproteinase 2 activity was evaluated with Gelatin zymography. The quantities of mRNA transcriptions of NF-κB p65, type I collagen, tissue inhibitor of metalloproteinases-1, α-smooth muscle actin and transforming growth factor beta 1 and anti-apoptotic protein A1 were evaluated with quantitative reverse transcriptase real-time polymerase chain reaction.

RESULTS

siRNA targetting NF-κB p65 effectively abrogated the expression of NF-κB p65 in hepatic stellate cells; decreased anti-apoptotic protein Bcl-2 and the mRNA transcription of hepatic type I collagen, α-smooth muscle actin, transforming growth factor beta 1, A1 and tissue inhibitor of metalloproteinases-1; increased matrix metalloproteinase 2 activity and promoted hepatic stellate cell apoptosis.

CONCLUSION

NF-κB knockdown enhances hepatic stellate cell apoptosis and attenuates extracellular matrix production.

Atorvastatin attenuates hepatic fibrosis in rats after bile duct ligation via decreased turnover of hepatic stellate cells

BACKGROUND & AIMS

Activation of hepatic stellate cells (HSC) and transdifferentiation to myofibroblasts following liver injury is the main culprit for hepatic fibrosis. Myofibroblasts show increased proliferation, migration, contraction, and production of extracellular matrix (ECM). In vitro, HMG-CoA reductase inhibitors (statins) inhibit proliferation and induce apoptosis of myofibroblastic HSC. To investigate the antifibrotic effects of atorvastatin in vivo we used bile duct ligated rats (BDL).

METHODS

BDL rats were treated with atorvastatin (15 mg/kg/d) immediately after ligation (prophylactically) or in on-going fibrosis (therapeutically). Fibrosis was assessed by hydroxyproline content and Sirius-red staining. The activation of HSC was investigated by analysis of alphaSMA expression. mRNA levels of cytokines and procollagen were analyzed by RT-PCR, and MMP-2 activity by zymography. Proliferation was assessed by expression of cathepsins (B and D), proliferating cell nuclear antigen (PCNA), and Ki67-staining. Apoptosis was characterized by caspase-3 activity, cleavage of PARP-1, and TUNEL assay. Hepatic inflammation was investigated by serum parameters and liver histology.

RESULTS

Prophylactic and early therapy with atorvastatin significantly attenuated fibrosis and HSC activation. Later therapy lacked significant effects on fibrosis but reduced profibrotic cytokine expression and led to a more quiescent state of HSC with less proliferation and apoptosis, while hepatic inflammation did not change.

CONCLUSIONS

This study shows that very early atorvastatin treatment inhibits HSC activation and fibrosis in the BDL model in vivo, while late treatment reduces HSC turnover and activity. Our findings underline that long-term studies in humans are warranted.

Epigenetic repression of matrix metalloproteinases in myofibroblastic hepatic stellate cells through histone deacetylases 4: implication in tissue fibrosis

Matrix metalloproteinases (MMPs), which are highly expressed in acute injury, are progressively repressed or silenced in fibrotic liver, favoring extracellular matrix accumulation, while the underlying mechanism is largely unknown. Similarly, normal/quiescent hepatic stellate cells (HSCs) express high levels of MMPs in response to injury signals, such as interleukin-1. After transdifferentiation, the myofibroblastic HSCs are incapable of expressing many MMPs; however, the major signaling pathways required for MMP expression are intact, indicating that repression is at the level of the chromatin. Indeed, both the MMP9 and MMP13 genes are inaccessible to transcription factors and RNA polymerase II, in association with impaired histone acetylation in their promoters. In accordance with impaired histone acetylation at the cellular level, histone deacetylase-4 is accumulated during HSC transdifferentiation. Furthermore, ectopic expression of histone deacetylase-4 in quiescent HSCs results in repression of MMP promoter activities as well as endogenous MMP9 protein expression. Thus, our findings suggest that a histone deacetylase-4-dependent mechanism underlies the epigenetic silencing of MMP genes during tissue fibrogenesis.

Effects of IFNα-2a on bcl-2 expression in the fibrotic liver of rats

AIM: To investigate the effects of interferon α-2a (IFNα-2a) on bcl-2 gene expression in the fibrotic liver of rats and explore potential mechanisms involved.

METHODS: Hepatic fibrosis was induced in rats by subcutaneous injection of carbon tetrachloride (CCl₄). Sprague-Dawley rats were randomly divided into normal control group, fibrosis model group and IFNα-2a intervention group. The expression of bcl-2 gene in the liver was detected by reverse transcription-polymerase chain reaction (RT-PCR). Liver tissue samples were taken for conventional hematoxylin and eosin (HE) staining and reticular fiber staining to observe histological changes.

RESULTS: A rat model of liver fibrosis was successfully established. IFNα-2a treatment significantly ameliorated liver fibrosis and fatty degeneration, but showed no impact on hepatic inflammation in fibrotic rats. The expression level of bcl-2 mRNA in the IFNα-2a intervention group was significantly lower than that in the fibrosis model group (P < 0.01), but higher than that in the normal control group (P < 0.01).

CONCLUSION: IFNα-2a can effectively ameliorate CCl₄-induced hepatic fibrosis and liver fatty degeneration possibly via a mechanism associated with downregulating bcl-2 gene expression and controlling apoptosis of HSC.

Loss of steroid receptor co-activator-3 attenuates carbon tetrachloride-induced murine hepatic injury and fibrosis

Hepatic fibrosis, a disease characterized by altered accumulation of extracellular matrix, can cause cirrhosis and liver failure. There is growing interest in the impact of co-activators on hepatic fibrogenesis. Here, we provided genetic evidence that mice lacking steroid receptor co-activator-3 (SRC-3) were protected against carbon tetrachloride (CCl4)-induced acute liver necrosis and chronic hepatic fibrosis. After acute CCl4 treatment, SRC-3(-/-) mice showed attenuated profibrotic response and hepatocyte apoptosis, whereas hepatocyte proliferation was elevated in SRC-3(-/-) mice versus SRC-3+/+ mice. Similarly, chronically CCl4-treated SRC-3(-/-) mice showed significant weakening of inflammatory infiltrates, hepatic stellate cell activation and collagen accumulation in the liver compared with SRC-3+/+ mice. Further investigation revealed that TGFbeta1/Smad signaling pathway was impaired in the absence of SRC-3. Moreover, the expression levels of SRC-3, as assessed in human tissue microarray of liver diseases, correlated positively with degrees of fibrosis. These data revealed that SRC-3(-/-) mice were resistant to CCl4-induced acute and chronic hepatic damage and TGFbeta1/Smad signaling was suppressed in the lack of SRC-3. Our results established an essential involvement of SRC-3 in liver fibrogenesis, which might provide new clues to the future treatment of hepatic fibrosis.

Loss of steroid receptor co-activator-3 attenuates carbon tetrachloride-induced murine hepatic injury and fibrosis

Hepatic fibrosis, a disease characterized by altered accumulation of extracellular matrix, can cause cirrhosis and liver failure. There is growing interest in the impact of co-activators on hepatic fibrogenesis. Here, we provided genetic evidence that mice lacking steroid receptor co-activator-3 (SRC-3) were protected against carbon tetrachloride (CCl4)-induced acute liver necrosis and chronic hepatic fibrosis. After acute CCl4 treatment, SRC-3(-/-) mice showed attenuated profibrotic response and hepatocyte apoptosis, whereas hepatocyte proliferation was elevated in SRC-3(-/-) mice versus SRC-3+/+ mice. Similarly, chronically CCl4-treated SRC-3(-/-) mice showed significant weakening of inflammatory infiltrates, hepatic stellate cell activation and collagen accumulation in the liver compared with SRC-3+/+ mice. Further investigation revealed that TGFbeta1/Smad signaling pathway was impaired in the absence of SRC-3. Moreover, the expression levels of SRC-3, as assessed in human tissue microarray of liver diseases, correlated positively with degrees of fibrosis. These data revealed that SRC-3(-/-) mice were resistant to CCl4-induced acute and chronic hepatic damage and TGFbeta1/Smad signaling was suppressed in the lack of SRC-3. Our results established an essential involvement of SRC-3 in liver fibrogenesis, which might provide new clues to the future treatment of hepatic fibrosis.

Dual role of CCR2 in the constitution and the resolution of liver fibrosis in mice

Inflammation has been shown to induce the progression of fibrosis in response to liver injury. Among inflammatory cells, macrophages and lymphocytes play major roles in both the constitution and resolution of liver fibrosis. The chemokine receptor CCR2 is involved in the recruitment of monocytes to injury sites, and it is known to be induced during the progression of fibrosis in humans. However, its specific role during this process has not yet been unveiled. We first demonstrated that, compared with wild-type mice, CCR2 knockout animals presented a delay in liver injury after acute CCl(4) injection, accompanied by a reduction in infiltrating macrophage populations. We then induced fibrosis using repeated injections of CCl(4) and observed a significantly lower level of fibrotic scars at the peak of fibrosis in mutant animals compared with control mice. This diminished fibrosis was associated with a reduction in F4/80(+)CD11b(+) and CD11c(+) populations at the sites of injury. Subsequent analysis of the kinetics of the resolution of fibrosis showed that fibrosis rapidly regressed in wild-type, but not in CCR2(-/-) mice. The persistence of hepatic injury in mutant animals was correlated with sustained tissue inhibitor of metalloproteinase-1 mRNA expression levels and a reduction in matrix metalloproteinase-2 and matrix metalloproteinase-13 expression levels. In conclusion, these findings underline the role of the CCR2 signaling pathway in both the constitution and resolution of liver fibrotic scars.

Effect of all-trans retinoic acid on liver fibrosis induced by common bile duct ligation in rats

The aim of this study was to investigate the effect and possible mechanism of all-trans retinoic acid (ATRA) on liver fibrosis induced by common bile duct ligation (CBDL) in rats. Fifty-three female Wistar rats were randomly divided into 5 groups: sham operation group (group J, 5 animals) and groups A, B, C and D (12 animals in each group). The rats in groups A, B, C and D were subjected to CBDL to induce liver fibrosis, while those in group J to sham operation. From the 3rd week the rats in groups B, C and D respectively received daily administration of ATRA via gastric tube at three different doses [0.1, 1.5 and 7.5 mg/kg body weight (BW)]. Animals were sacrificed at 6th week. Rats' liver tissues were observed for pathologic changes under a light microscope. The protein levels of type I collagen (COL I), matrix metalloproteinase-2 (MMP2), MMP13 and tissue inhibitors of metalloproteinase-1 (TIMP-1) in liver tissues were determined by immunohistochemical techniques. The expression levels of TGF-beta1 and CTGF mRNA in liver tissues were detected by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). The results showed that loss of normal hepatic architecture and formation of obvious fibrosis were observed in group A, while ATRA treatment for 4 weeks notably alleviated the pathological changes of hepatocytes. The expression of COL I and TIMP-1 proteins in group A was increased, while decreased in ATRA-treated CBDL groups (P<0.05). ATRA (1.5 and 7.5 mg/kg BW) reduced the expression levels of COL I protein more greatly than that of 0.1 mg/kg BW (P<0.05). ATRA treatment increased the protein levels of MMP2 and MMP13. The expression levels of TGF-beta1 and CTGF mRNA in group A were increased. In comparison with group A, the mRNA levels of TGF-beta1 and CTGF in ATRA-treated CBDL groups were significantly decreased (P<0.05). It was concluded that ATRA could inhibit CBDL-induced liver fibrosis in rats by suppressing the expression of TGF-beta1 and CTGF so as to diminish the inhibition of TIMP-1 on MMP2 and MMP13 and increase the activity of MMP2 and MMP13.

Disruption of tissue-type plasminogen activator gene in mice aggravated liver fibrosis

BACKGROUND AND AIM

Tissue-type plasminogen activator (tPA) is one of the major components in the matrix proteolytic network whose role in the pathogenesis of liver fibrosis remains unknown. The aim of this study is to investigate the role of tPA in carbon tetrachloride (CCl(4))-induced liver fibrosis.

METHODS

Wild-type and tPA knockout mice (8 mice per group) were injected interperitoneumly with 25% CCl(4) 2 ml/kg twice per week as CCl(4) administration groups and olive oil 2 ml/kg as controls. After 4 weeks, the livers of mice were removed under deep anesthesia and prepared for further studies such as histology, immunostaining, hydroxyproline assay, zymography and western blot analysis.

RESULTS

Mice lacking tPA developed more severe morphological injury and displayed an increased deposition of collagen in the liver after CCl(4) administration compared with wild-type counterparts. Deficiency of tPA increased alpha-smooth muscle actin expression in the mice livers. On the other hand, the decrease of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) activities, metalloproteinase-13 (MMP-13) expression and a marked increase of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) expression were found in the liver of CCl(4) administrated tPA(-/-) mice compared with wild-type counterparts.

CONCLUSIONS

Deficiency of tPA aggravated liver fibrosis through promoting hepatic stellate cells (HSCs) activation and inhibiting ECM degradation by decreasing MMP-2, MMP-9 activities and disrupting the balance between MMP-13 and TIMP-1.

Effect of angiotensin-converting enzyme inhibition on experimental hepatic fibrogenesis

The renin-angiotensin system is suggested to be important in liver fibrogenesis. It induces hepatic stellate cell proliferation and up-regulates transforming growth factor beta-1 (TGF-beta1) expression. Matrix metalloproteinase-2 (MMP-2) is involved in extracellular matrix remodelling. Fibrosis, a consequence of most chronic liver diseases, may be the result of a disturbed balance between fibrogenesis and fibrolysis. The aim of this study was to investigate the effect of enalapril on liver fibrogenesis induced in rats by bile-duct ligation. Forty-seven rats were divided into two groups: bile-duct ligated (BDL) (n = 24) and BDL + enalapril (n = 23). Fibrosis was evaluated by the Knodell scoring system, and TGF-beta1 and MMP-2 were assessed with immunohistochemistry at the second, fourth and sixth weeks after bile-duct ligation. In the BDL group, TGF-beta1 increased by the second week and this increase continued through weeks 4 and 6. In the BDL + enalapril group, TGF-beta1 was significantly lower than the other group (P < 0.05). MMP-2 progressively decreased after week 2 in the BDL group. In the BDL + enalapril group, MMP-2 was significantly higher than the BDL group at the fourth and sixth weeks. These results suggest that enalapril reduces the liver tissue TGF-beta1 and has an ameliorating effect on the fibrosis markers TGF-beta1 and MMP-2.

Therapeutic mechanism of interferon's anti-hepatic fibrosis action

Hepatic fibrosis is a common pathological change occurring in chronic liver disease which is induced by a variety of etiological factors. Hepatic fibrosis is a dynamic process, and a reversible pathological change. However, when it has progressed to hepatic cirrhosis, it is irreversible. Therefore, to block or reverse the course of hepatic fibrosis is a very significant target for the treatment of chronic liver disease. Interferon (IFN) has extensive functions, including anti-viral, anti-tumor and immunological roles. Recent research has reported that IFN possesses an anti-hepatic fibrosis function, with potential clinical application. However, the exact mechanism underlying its anti-hepatic fibrosis action remains unknown. Some scholars believe that this mechanism involves interferon's anti-viral effects, the inhibition of hepatic stellate cell (HSC) activation, the promotion of HSC apoptosis, the inhibition of extracellular matrix (ECM) synthesis and the promotion of ECM degradation.

Expression of MMPs and TIMPs in liver fibrosis - a systematic review with special emphasis on anti-fibrotic strategies

In liver tissue matrix metalloproteinases (MMPs) and their specific inhibitors (tissue inhibitors of metalloproteinases, TIMPs) play a pivotal role in both, fibrogenesis and fibrolysis. The current knowledge of the pathophysiology of liver fibrogenesis with special emphasis on MMPs and TIMPs is presented. A systematic literature search was conducted. All experimental models of liver fibrosis that evaluated a defined anti-fibrotic intervention in vivo or in vitro considering MMPs and TIMPs were selected. The methodological quality of all these publications has been critically appraised using an objective scoring system and the content has been summarized in a table.

A matrix metalloproteinase-9 activation cascade by hepatic stellate cells in trans-differentiation in the three-dimensional extracellular matrix

Hepatic stellate cells (HSCs) undergo myofibroblastic trans-differentiation in liver fibrogenesis. We previously showed that dual stimulation with three-dimensional type-I collagen and interleukin-1 (IL-1) synergistically induces HSC trans-differentiation in a manner dependent on the activation of matrix metallopreinase-9 (MMP-9). The present study is aimed to determine the mechanism of MMP-9 activation in this model. The pro-MMP-9-converting activities expressed by trans-differentiating HSCs are characterized as secreted factors that are sensitive to MMP inhibitor and have apparent molecular masses of 50 and 25 kDa. This is in sharp contrast to the pro-MMP-9 activator from mouse and human skin, which is a chymotrypsin-like proteinase. Among multiple MMPs induced in HSCs by the dual stimulation, MMP-13 is most conspicuously up-regulated and meets all criteria as the pro-MMP-9 activator. HSC cultured in three-dimensional type-I collagen, but not in Matrigel, IL-1 induces expression of MMP-13 and its matured form at 50 and 25 kDa, respectively. In vitro reconstitution experiment proves that MMP-13, but not its zymogen, activates pro-MMP-9. Further, short hairpin RNA targeting MMP-13 abolishes pro-MMP-9 activation and HSC trans-differentiation. We further demonstrate that pro-MMP-13 activation is facilitated with a membrane-associated factor, inhibited with tissue inhibitor of metalloproteinase-2, and abolished with short hairpin RNA against MMP-14. Moreover, pro-MMP-13 is also activated by a secreted factor, which is absorbed by gelatin-Sepharose and reconstituted with MMP-9. Thus, IL-1-induced trans-differentiation of HSCs in three-dimensional extracellular matrix is facilitated by an MMP activation cascade (MMP-14 > MMP-13 > MMP-9) and a positive feedback loop of MMP-9 > MMP-13, suggesting their critical roles in liver injury and repair.

Low-dose oral rapamycin treatment reduces fibrogenesis, improves liver function, and prolongs survival in rats with established liver cirrhosis

BACKGROUND/AIMS

Mammalian target of rapamycin (mTOR) signalling is central in the activation of hepatic stellate cells (HSCs), the key source of extracellular matrix (ECM) in fibrotic liver. We tested the therapeutic potential of the mTOR inhibitor rapamycin in advanced cirrhosis.

METHODS

Cirrhosis was induced by bile duct-ligation (BDL) or thioacetamide injections (TAA). Rats received oral rapamycin (0.5 mg/kg/day) for either 14 or 28 days. Untreated BDL and TAA-rats served as controls. Liver function was quantified by aminopyrine breath test. ECM and ECM-producing cells were quantified by morphometry. MMP-2 activity was measured by zymography. mRNA expression of procollagen-alpha1, transforming growth factor-beta1 (TGF-beta1) and beta2 was quantified by RT-PCR.

RESULTS

Fourteen days of rapamycin improved liver function. Accumulation of ECM was decreased together with numbers of activated HSCs and MMP-2 activity in both animal models. TGF-beta1 mRNA was downregulated in TAA, TGF-beta2 mRNA was downregulated in BDL. 28 days of rapamycin treatment entailed a survival advantage of long-term treated BDL-rats.

CONCLUSIONS

Low-dose rapamycin treatment is effectively antifibrotic and attenuates disease progression in advanced fibrosis. Our results warrant the clinical evaluation of rapamycin as an antifibrotic drug.

Reversal of fibrosis: no longer a pipe dream?

The reversal of liver fibrosis is not a new phenomenon. Treatment of the primary disease remains the most effective strategy, but new approaches to promote resolution of fibrosis are being built on the foundations that were provided by research into the basic mechanisms of fibrogenesis. A return to normal hepatic architecture from advanced fibrosis is achievable in some cases, and cirrhosis itself may be partly remediable.

Oral imatinib treatment reduces early fibrogenesis but does not prevent progression in the long term

BACKGROUND/AIMS

Transactivated hepatic stellate cells (HSCs) represent the key source of extra cellular matrix (ECM) in fibrotic liver. Imatinib, a potent inhibitor of the PDGF receptor tyrosine kinase, reduces HSC proliferation and fibrogenesis when treatment is initiated before fibrosis has developed. We tested the antifibrotic potential of imatinib in ongoing liver injury and in established fibrosis.

METHODS

BDL-rats were gavage fed with 20 mg/kg/d imatinib either early (days 0-21) or late (days 22-35) after BDL. Untreated BDL-rats served as controls. ECM and activated HSCs were quantified by morphometry. Tissue activity of MMP-2 was determined by gelatin zymography. mRNA expression of TIMP-1 and procollagen alpha1(I) were measured by RT-PCR. Liver tissue concentration of imatinib was measured by tandem mass spectrometry.

RESULTS

Early imatinib reduced ECM formation by 30% (P=0.0455) but left numbers of activated HSCs and procollagen I expression unchanged. MMP-2 activity and TIMP-1 expression were reduced by 50%. Late imatinib treatment did not alter histological or molecular markers of fibrogenesis despite high imatinib tissue levels.

CONCLUSIONS

The antifibrotic effectiveness of imatinib is limited to the early phase of fibrogenesis. In ongoing liver injury other mediators most likely compensate for the inhibited PDGF effect.

Mechanisms of liver fibrosis

Liver fibrosis represents a significant health problem worldwide of which no acceptable therapy exists. The most characteristic feature of liver fibrosis is excess deposition of type I collagen. A great deal of research has been performed to understand the molecular mechanisms responsible for the development of liver fibrosis. The activated hepatic stellate cell (HSC) is the primary cell type responsible for the excess production of collagen. Following a fibrogenic stimulus, HSCs change from a quiescent to an activated, collagen-producing cell. Numerous changes in gene expression are associated with HSC activation including the induction of several intracellular signaling cascades, which help maintain the activated phenotype and control the fibrogenic and proliferative state of the cell. Detailed analyses in understanding the molecular basis of collagen gene regulation have revealed a complex process offering the opportunity for multiple potential therapeutic strategies. However, further research is still needed to gain a better understanding of HSC activation and how this cell maintains its fibrogenic nature. In this review we describe many of the molecular events that occur following HSC activation and collagen gene regulation that contribute to the fibrogenic nature of these cells and provide a review of therapeutic strategies to treat this disease.

Gene expression profile analysis of spontaneous reversion of CCl4-induced hepatic fibrosis in rats

AIM: To screen the differentially expressed gene in the spontaneous reversion of hepatic fibrosis induced by carbon tetrachloride (CCl₄), and to reveal the gene expression profile in this process.

METHODS: Animal model of hepatic fibrosis with spontaneous reversion was created in SD rats by injection of carbon tetrachloride (CCl₄) for 8 weeks and then withdrawing for 6 weeks. The mRNA of liver tissues was extracted at different time spots in the process of reversion. Then cDNA microarray was used to screen the differentially expressed genes. Finally the products were subjected to hierarchical clustering and confirmed by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) of α-synuclein, A-raf, presenilin-2 and β-actin.

RESULTS: Hepatic fibrosis was progressively reversed after stopping injection of CCl₄. All together, there were 254 (21.59%) genes that changed at the transcription level. Meanwhile, 54, 85, 97 and 132 genes were identified differentially expressed in the 8^th, 10^th, 12^th and 14^th week, respectively. After confirmed by RT-PCR, the differentially expressed were associated with metabolic enzymes, ion channels, transcription factors, gastrointestinal hormones and their receptors, mitogen-activated protein kinase (MAPK) and PI3k/Akt signaling pathway.

CONCLUSION: The gene expression profile is significantly changed in the spontaneous recovery of CCl₄-induced hepatic fibrosis. Genes closely related to the spontaneous recovery are associated with metabolic enzymes, transporter/symporter proteins, gastrointestinal hormones/receptors, lipoprotein/fatty acid binding proteins, transcription factor/nuclear factors, and MAPK signal pathway.

Metallothionein gene therapy for chemical-induced liver fibrosis in mice

Liver fibrogenesis resulting from a diversity of pathological changes involves a disturbance in mineral, in particular zinc, homeostasis. The present study was undertaken to determine whether gene therapy with metallothionein (MT), a small protein critically involved in the regulation of zinc homeostasis, can improve the recovery of liver fibrosis in a mouse model. Wild-type (WT) mice treated with carbon tetrachloride in corn oil twice a week at 1 ml/kg for 4 weeks developed a reversible liver fibrosis upon removal of the chemical, correlating with a high level of hepatic MT; but those treated for 8 weeks developed an irreversible liver fibrosis along with low levels of hepatic MT. The same carbon tetrachloride treatment for 4 weeks resulted in an irreversible liver fibrosis in MT-knockout (MT-KO) mice. Adenoviral delivery of the human MT-II gene (approved symbol MT2A) through intravenous injection reversed the fibrosis along with increased hepatocyte regeneration within 3 days in both WT and MT-KO mice with irreversible fibrosis. The MT elevation was associated with increased activities of collagenases in the liver. This study indicates that MT makes a critical contribution to the reversal of chemical-induced hepatic fibrosis and has therapeutic potential for patients with certain liver fibrosis.

Peroxynitrite-mediated matrix metalloproteinase-2 activation in human hepatic stellate cells

To investigate whether hepatic stellate cells (HSCs) alter their expression of MMPs after exposure to nitrogen oxide intermediate (NOI), a human hepatic stellate cell line, LI90 cells, was stimulated with an NO donor, SNAP, or a peroxynitrite donor, SIN-1, and the culture supernatants were analyzed by gelatin zymography or anti-MMPs immunoblot. Although SIN-1 did not enhance the secretions of MMP-1 and 13, SIN-1 induced the NF-kappaB activation, MT1-MMP expression and the secretion of activated MMP-2 in LI90 cells. These results suggest that peroxynitrite may contribute to the remodeling of the extracellular matrix in liver by activating pro-MMP-2.

Effects of interferon-alpha on expression of hepatic stellate cell and transforming growth factor-β1 and α-smooth muscle actin in rats with hepatic fibrosis

AIM: To investigate the effect of interferon-α (IFN-α) on preventing or reversing hepatic fibrosis in rat experimental model induced by CCl₄.

METHODS: One hundred and ten Sprague-Dawley rats were divided into five groups: group A (normal controls, n = 18), group B (fibrotic model controls, n = 22), group C (IFN-α prevention, n = 22) initially treated with intra-muscular injection of IFN-α in saline daily at the doses of 1×10⁵ U for 6 wk, group D (IFN-α treatment, n = 24) treated with intra-muscular injection of IFN-α in saline daily at the doses of 1×10⁵ U for 6 wk after the first 6 wk, group E (0.9% sodium chloride treatment control, n = 24) treated with intra-muscular injection of 0.01 mL/kg daily for 6 wk after the first 6 wk. At the end of the experiment, all rats of each group were killed. Samples of the liver obtained by biopsy were subjected to histological, immunohistochemical and electron microscopic studies for the expressions of transforming growth factor-β1 (TGF- β1) and α-smooth muscle actin (α-SMA).

RESULTS: The expressions of TGF-β1, the number of activated hepatic stellate cells and α-SMA in hepatic tissue of group C were significantly less than those of group B (P<0.01). The degree of fibrosis score in group B was also significantly less than that of group C under light microscope (P<0.01).

CONCLUSION: IFN-α can inhibit the production of TGF-β1, decrease HSC activation and stimulate its apoptosis.

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Dynamic changes in the expression of matrix metalloproteinases and their inhibitors, TIMPs, during hepatic fibrosis induced by alcohol in rats

AIM: To determine the dynamic changes in the expression of matrix metalloproteinases (MMPs) and the endogenous tissue inhibitors of MMPs inhibitors (TIMPs) during hepatic fibrosis induced by alcohol.

METHODS: Male Sprague-Dawley rats were randomly divided into normal, 4 d, 2 wk, 4 wk, 9 wk and 11 wk groups, and the model rats were fed with a mixture of alcohol by gastric infusion at the designed time, respectively, then decollated and their livers were harvested for the examination of MMP-2, MMP-3, MMP-9, MMP-13, TIMP-1 and TIMP-2 by immunoh-istochemistry, zymograghy and Western blotting, respectively.

RESULTS: Normal rats had moderate expression of MMP-2, which was decreased in the model rats except in the 11 wk group, where MMP-2 expression slightly increased. MMP-3 had the similar changing pattern to MMP-2 despite weaker expression. MMP-9 expression decreased in the 4 d and 2 wk groups, rose in the 4 wk group, decreased again in the 9 wk group and returned to normal levels in the 11 wk group. MMP-13 expression decreased in the 4 d and 2 wk groups, and returned to normal levels in the 4 wk, 9 wk and 11 wk groups. TIMP-1 expression decreased in the 4 d and 2 wk groups, but sharply increased in the 4 wk group and sustained at a high level even after modeling was stopped for 2 wk. In normal rats TIMP-2 expression was strong. However, it decreased as soon as modeling began, and then gradually rose, but remained to a level lower than that in normal rats even after modeling was stopped for 2 wk.

CONCLUSION: MMP-2 may not always expresses at a high level during hepatic fibrosis. MMP-13 and MMP-3 are acutely affected by TIMP-1. In this model TIMP-1 is the most powerful factor imposed on capillarization and peri-sinusoidal fibrosis. TIMP-2 is the most effective regulator on the metabolism of type IV collagen located in the basement of sinus.

Antifibrotic effects of a tissue inhibitor of metalloproteinase-1 antibody on established liver fibrosis in rats

Liver fibrosis is characterized by increased synthesis, and decreased degradation, of extracellular matrix (ECM) within the injured tissue. Decreased ECM degradation results, in part, from increased expression of tissue inhibitor of metalloproteinase-1 (TIMP-1), which blocks matrix metalloproteinase (MMP) activity. TIMP-1 is also involved in promoting survival of activated hepatic stellate cells (HSCs), a major source of ECM. This study examined the effects of blocking TIMP-1 activity in a clinically relevant model of established liver fibrosis. Rats were treated with carbon tetrachloride (CCl(4)), or olive oil control, for 6 weeks; 24 days into the treatment, the rats were administered a neutralizing anti-TIMP-1 antibody derived from a fully human combinatorial antibody library (HuCAL), PBS, or an isotype control antibody. Livers from CCl(4)-treated rats exhibited substantial damage, including bridging fibrosis, inflammation, and extensive expression of smooth muscle alpha-actin (alpha-SMA). Compared to controls, rats administered anti-TIMP-1 showed a reduction in collagen accumulation by histological examination and hydroxyproline content. Administration of anti-TIMP-1 resulted in a marked decrease in alpha-SMA staining. Zymography analysis showed antibody treatment decreased the activity of MMP-2. In conclusion, administration of a TIMP-1 antibody attenuated CCl(4)-induced liver fibrosis and decreased HSC activation and MMP-2 activity.

Expression of matrix metalloproteinase-2 and -14 persists during early resolution of experimental liver fibrosis and might contribute to fibrolysis

BACKGROUND/AIMS

Resolution of liver fibrosis is possible but the identity of the matrix metalloproteinases (MMPs) which degrade the accumulated collagens is uncertain. We examined MMP-2 and MMP-14 expression in established and resolving fibrosis to assess their role in resolution of liver fibrosis.

METHODS

MMP and tissue inhibitor of metalloproteinase (TIMP)-2 expression in liver extracts was examined by ribonuclease protection assay, Western blotting and gelatin zymography. MMP activity was examined by (14)C gelatin degradation.

RESULTS

In human cirrhotic liver, MMP-14 mRNA was increased to 230-330% of normal liver expression. Both 63 kDa proenzyme and 60 kDa activated form were present. Cirrhotic livers had 270-320% of normal liver expression of MMP-2 protein with 20-25% being the 62 Da activated form. Protein and mRNA for MMP-2 and MMP-14 progressively increased during 8 weeks of CCl(4) treatment in rats. Between 3 and 7 days of resolution from CCl(4) liver fibrosis, MMP-2 and MMP-14 persisted at elevated levels. Gelatinolytic activity in liver homogenates peaked at 7 days of recovery, being 140% above that in livers at peak fibrosis.

CONCLUSIONS

Increased expression and activation of MMP-2 and -14 occurs even under conditions of elevated TIMPs during liver fibrogenesis. During liver fibrosis resolution, as TIMP expression decays, the persistence of MMP-2 and MMP-14 may permit collagen degradation.

c-Jun NH2-terminal kinase pathway is involved in constitutive matrix metalloproteinase-1 expression in a hepatocellular carcinoma-derived cell line

Transcription factor c-Jun serves for cellular proliferation, survival, differentiation and transformation and is recognized as an important factor in cancer development, including hepatocellular carcinoma (HCC). The purpose of present study is to determine the involvement of c-Jun in matrix metalloproteinase-1 (MMP-1) expression, which is previously reported by us to be expressed only in the early stage of human HCC showing stromal invasion. Of 5 human HCC cell lines examined, only HLE cells revealed mRNA and protein expression as well as enzymatic activity of MMP-1. Transient transfection of an MMP-1 promoter/luciferase construct (including 4.4 kb full promoter region) into HLE and HCC-T cells (MMP-1 nonproducer) showed that high promoter activity was observed only in HLE cells without inducers, and that this promoter activity was still observed when a shorter 0.6 kb proximal promoter construct was transfected. The 0.6 kb promoter region contained 3 AP-1 sites, and c-jun mRNA was constitutively expressed in HLE cells without inducers. Furthermore, phosphorylated c-Jun and c-Jun NH2-terminal kinase (JNK) were detected in HLE cells. Promoter activity of the 0.6 kb construct was suppressed with SP600125, a potent inhibitor of JNK, but not with PD98059 and SB203580, potent inhibitors of MEK1/2 and p38, respectively. The inhibitory effect of SP600125 was also observed at protein expression level and in enzymatic activity of MMP-1. Taken together, this study suggests that the JNK pathway is involved in the expression of MMP-1 in HCC cells and may represent a new functional role of c-Jun for HCC development.