Effects of long-term administration of interferon alpha in two models of liver fibrosis in rats

Mouse Type-I Interferon-Mannosylated Albumin Fusion Protein for the Treatment of Chronic Hepatitis

Although a lot of effort has been put into creating drugs and combination therapies against chronic hepatitis, no effective treatment has been established. Type-I interferon is a promising therapeutic for chronic hepatitis due to its excellent anti-inflammatory effects through interferon receptors on hepatic macrophages. To develop a type-I IFN equipped with the ability to target hepatic macrophages through the macrophage mannose receptor, the present study designed a mouse type-I interferon-mannosylated albumin fusion protein using site-specific mutagenesis and albumin fusion technology. This fusion protein exhibited the induction of anti-inflammatory molecules, such as IL-10, IL-1Ra, and PD-1, in RAW264.7 cells, or hepatoprotective effects on carbon tetrachloride-induced chronic hepatitis mice. As expected, such biological and hepatoprotective actions were significantly superior to those of human fusion proteins. Furthermore, the repeated administration of mouse fusion protein to carbon tetrachloride-induced chronic hepatitis mice clearly suppressed the area of liver fibrosis and hepatic hydroxyproline contents, not only with a reduction in the levels of inflammatory cytokine (TNF-α) and fibrosis-related genes (TGF-β, Fibronectin, Snail, and Collagen 1α2), but also with a shift in the hepatic macrophage phenotype from inflammatory to anti-inflammatory. Therefore, type-I interferon-mannosylated albumin fusion protein has the potential as a new therapeutic agent for chronic hepatitis.

The presence of interferon affects the progression of non-alcoholic fatty liver disease

Inflammation and metabolic dysfunction are hallmarks of the progression of non-alcoholic fatty liver disease (NAFLD), which is the fastest-growing liver disease worldwide. Emerging evidence indicates that innate immune mechanisms are essential drivers of fibrosis development in chronic inflammatory liver diseases, including NAFLD. In this study, 142 NAFLD patients were genotyped for three IFNL4 single-nucleotide variants in order to investigate the genetic relationship between IFNL4 and fibrosis in NAFLD patients. We observed an overrepresentation of the non-functional IFNL4 allele in patients with significant fibrosis (>F2). Next, we investigated the potential protective role of interferon (IFN) in relation to the development of liver fibrosis in an animal model of non-alcoholic steatohepatitis (NASH). In contradiction to our hypothesis, the results showed an increase in fibrosis in IFN treated animals. Our study clearly indicates that IFN is able to affect the development of liver fibrosis, although our clinical and experimental data are conflicting.

Pro- and Anti-fibrogenic Functions of Gram-Negative Bacterial Lipopolysaccharide in the Liver

Extensive research performed over several decades has identified cells participating in the initiation and progression of fibrosis, and the numerous underlying inter- and intra-cellular signaling pathways. However, liver fibrosis continues to be a major clinical challenge as the precise targets of treatment are still elusive. Activation of physiologically quiescent perisinusoidal hepatic stellate cells (HSCs) to a myofibroblastic proliferating, contractile and fibrogenic phenotype is a critical event in the pathogenesis of chronic liver disease. Thus, elucidation of the mechanisms of the reversal to quiescence or inhibition of activated HSCs, and/or their elimination via apoptosis has been the focus of intense investigation. Lipopolysaccharide (LPS), a gut-resident Gram-negative bacterial endotoxin, is a powerful pro-inflammatory molecule implicated in hepatic injury, inflammation and fibrosis. In both acute and chronic liver injury, portal venous levels of LPS are elevated due to increased intestinal permeability. LPS, via CD14 and Toll-like receptor 4 (TLR4) and its adapter molecules, stimulates macrophages, neutrophils and several other cell types to produce inflammatory mediators as well as factors that can activate HSCs and stimulate their fibrogenic activity. LPS also stimulates synthesis of pro- and anti-inflammatory cytokines/chemokines, growth mediators and molecules of immune regulation by HSCs. However, LPS was found to arrest proliferation of activated HSCs and to convert them into non-fibrogenic phenotype. Interestingly, LPS can elicit responses in HSCs independent of CD14 and TLR4. Identifying and/or developing non-inflammatory but anti-fibrogenic mimetics of LPS could be relevant for treating liver fibrosis.

1-Methyl-L-tryptophan promotes the apoptosis of hepatic stellate cells arrested by interferon-γ by increasing the expression of IFN-γRβ, IRF-1 and FAS

Liver fibrosis, a precursor to cirrhosis, is the result of the deposition of extracellular matrix (ECM) proteins and is mediated primarily by activated hepatic stellate cells (HSCs). In this study, we investigated the anti-fibrotic effects of interferon (IFN)-γ in activated HSCs in vitro and whether cell viability would be decreased by the inhibition of indoleamine 2,3-dioxygemase (IDO), which is responsible for cell cycle arrest. Following treatment with IFN-γ, cell signaling pathways and DNA content were analyzed to assess the inactivation of HSCs or the decrease in HSC proliferation. The IDO inhibitor, 1-methyl-L-tryptophan (1-MT), was used to determine whether IDO plays a key role in the regulation of activated HSCs, as IFN-γ increases the expression of IDO. IFN-γ significantly inhibited the growth of HSCs and downregulated the expression of α-smooth muscle actin (α-SMA) in the HSCs. IDO expression was markedly increased by IFN-γ through signal transducer and activator of transcription 1 (STAT1) activation and resulted in the depletion of tryptophan. This depletion induced G1 cell cycle arrest. When the cells were released from IFN-γ-mediated G1 cell cycle arrest by treatment with 1-MT, the apoptosis of the HSCs was markedly increased through the induction of IFN-γRβ, interferon regulatory factor (IRF-1) and FAS. Our results thus suggest that the inhibition of IDO enhances the suppression of activated HSCs, and therefore co-treatment with IFN-γ and 1-MT may be applied to ameliorate liver fibrosis.

Icariin-treated human umbilical cord mesenchymal stem cells decrease chronic liver injury in mice

Human umbilical cord mesenchymal stem cells (hUMSCs) have been shown to have multiple differentiation potentials. However, a key problem is that only a small number of hUMSCs can migrate to damaged tissue after transplantation. According to "The Theory of Kidney Essence" in Traditional Chinese Medicine, some traditional Chinese medicines used for tonifying the kidneys can be applied in promoting the differentiation and migration of stem cells in vivo. Our previous study demonstrated that icariin (ICA) could up-regulate the pluripotent genes of hUMSCs in vitro and induce cell migration in mice in an acute kidney injury model in vivo. The aim of this study was to investigate the effects of ICA-induced hUMSCs in chronic liver injury (CLI) caused by carbon tetrachloride (CCl4). CLI was induced by intraperitoneal injection of CCl4. ICA-treated hUMSCs were transplanted via intra-venous injection. The animals were followed for survival, biochemistry analysis and pathology. The results show that ICA-treated hUMSCs accelerate the recovery of liver function in mice with CLI. In addition, ICA-treated hUMSCs increase the anti-oxidant activities in liver and prevent the progression to hepatic fibrosis. Moreover, ICA induces the migration of hUMSCs to the injured liver tissue. In conclusion, these data demonstrate that ICA-treated hUMSCs exhibit recovery and protective properties in the mice model of CCl4-induced CLI.

Toll-like receptor 7-mediated type I interferon signaling prevents cholestasis- and hepatotoxin-induced liver fibrosis

Toll-like receptor 7 (TLR7) signaling predominantly regulates production of type I interferons (IFNs), which has been suggested in clinical studies to be antifibrotic. However, the mechanistic role of the TLR7-type I IFN axis in liver fibrosis has not been elucidated. In the present study, liver fibrosis was induced in wild-type (WT), TLR7-deficient, and IFN-α/β receptor-1 (IFNAR1)-deficient mice and TLR7-mediated signaling was assessed in liver cells isolated from these mice. TLR7-deficient and IFNAR1-deficient mice were more susceptible to liver fibrosis than WT mice, indicating that TLR7-type I IFN signaling exerts a protective effect against liver fibrosis. Notably, the hepatic expression of interleukin-1 receptor antagonist (IL-1ra) was suppressed in TLR7- or IFNAR1-deficient mice compared with respective WT mice, and treatment with recombinant IL-1ra reduced liver fibrosis. In vivo activation of TLR7 significantly increased IFNa4 and IL-1ra expression in the liver. Interestingly, each cytokine had a different cellular source, showing that dendritic cells (DCs) are the responsible cell type for production of type I IFN, while Kupffer cells (KCs) mainly produce IL-1ra in response to type I IFN. Furthermore, TLR7 activation by R848 injection suppressed liver fibrosis and production of proinflammatory cytokines, and these effects were dependent on type I IFN signaling. Consistent with in vivo data, IFN-α significantly induced IL-1ra production in primary KCs.

CONCLUSION

TLR7 signaling activates DCs to produce type I IFN, which in turn induces antifibrogenic IL-1ra production in KCs. Thus, manipulation of the TLR7-type I IFN-IL-1ra axis may be a new therapeutic strategy for the treatment of liver fibrosis.

Randomized clinical trial: a pilot study investigating the safety and effectiveness of an escalating dose of peginterferon α-2a monotherapy for 48 weeks compared with standard clinical care in patients with hepatitis C cirrhosis

BACKGROUND

A substantial proportion of patients with chronic hepatitis C virus (HCV) cirrhosis fail to eradicate infection and develop liver-related complications. Despite evidence that interferon-α has an antifibrotic effect, clinical trials have demonstrated that low-dose maintenance interferon does not improve outcomes in patients with compensated HCV cirrhosis following a lead-in phase of interferon. In a pilot study, we have investigated the efficacy of an escalating dose of pegylated interferon α-2a (PEG-IFN2a) as compared with standard clinical care in patients with more advanced HCV Child's A or B cirrhosis without a lead-in phase.

METHODS

In a prospective study, 40 patients were randomized to receive either standard clinical care (no further antiviral therapy) or 48 weeks of treatment with PEG-IFN2a starting at 90 mcg and escalating to 180 mcg weekly if tolerated. Patients were thereafter followed for a mean duration of 41 months. The primary outcome variables were liver-related death, all-cause mortality and sustained virological response. The secondary outcomes were 'liver-related events' and health-related quality of life.

RESULTS

Both groups were well matched, with treatment well tolerated. The incidences of all-cause mortality (P=0.024) and nononcological liver morbidity (P=0.04) were significantly higher in the control arm after a mean of 47 months of follow-up.

CONCLUSION

A 48-week escalating dose of PEG-IFN2a is associated with a significant reduction in all-cause mortality and nononcological liver-related morbidity in this trial. Further investigation of PEG-IFN2a is warranted for patients with advanced HCV-related cirrhosis for whom there is no other treatment and where transplantation is associated with rapid progression to cirrhosis.

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.

Down-regulation of cyclin E1 expression by microRNA-195 accounts for interferon-β-induced inhibition of hepatic stellate cell proliferation

Recent studies have suggested that interferons (IFNs) have an antifibrotic effect in the liver independent of their antiviral effect although its detailed mechanism remains largely unknown. Some microRNAs have been reported to regulate pathophysiological activities of hepatic stellate cells (HSCs). We performed analyses of the antiproliferative effects of IFNs in HSCs with special regard to microRNA-195 (miR-195). We found that miR-195 was prominently down-regulated in the proliferative phase of primary-cultured mouse HSCs. Supporting this fact, IFN-β induced miR-195 expression and inhibited the cell proliferation by delaying their G1 to S phase cell cycle progression in human HSC line LX-2. IFN-β down-regulated cyclin E1 and up-regulated p21 mRNA levels in LX-2 cells. Luciferase reporter assay revealed the direct interaction of miR-195 with the cyclin E1 3'UTR. Overexpression of miR-195 lowered cyclin E1 mRNA and protein expression levels, increased p21 mRNA and protein expression levels, and inhibited cell proliferation in LX-2 cells. Moreover miR-195 inhibition restored cyclin E1 levels that were down-regulated by IFN-β. In conclusion, IFN-β inhibited the proliferation of LX-2 cells by delaying cell cycle progression in G1 to S phase, partially through the down-regulation of cyclin E1 and up-regulation of p21. IFN-induced miR-195 was involved in these processes. These observations reveal a new mechanistic aspect of the antifibrotic effect of IFNs in the liver.

Inhibitory effect of human interferon-beta-1a on activated rat and human hepatic stellate cells

BACKGROUND AND AIMS

Hepatic stellate cells (HSC) are the primary cell type mediating hepatic fibrosis. Although known for its antiviral effects, the inhibitory effects of interferon-beta (IFN-β) on HSC treatment have not yet been established.

METHODS

Both human and rat activated HSC cell lines were incubated with increasing concentrations of recombinant human IFN-β1a (rhIFN-β1a) for 24, 48 or 72 h. The effects of rhIFN-β1a on α-smooth muscle actin (α-SMA), collagen types I and III, transforming growth factor-β1 (TGF-β1), platelet-derived growth factor-BB (PDGF-BB), and mothers against decapentaplegic homolog (Smad4, Smad7) expression in HSC were examined using Western blotting and immunocytochemistry. Proliferation of HSC was evaluated via bromodeoxyuridine assay.

RESULTS

rhIFN-β1a treatment had a dose-dependent, inhibitory effect on α-SMA and collagen type I protein expression. In addition, rhIFN-β1a decreased the expression of collagen type III, TGF-β1, PDGF-BB and Smad4 protein expression in HSC compared with untreated cells. We also observed increased Smad7 protein expression and decreased proliferation in rhIFN-β1a-treated HSC.

CONCLUSIONS

Our data suggest that rhIFN-β1a treatment decreased α-SMA and collagen expression and inhibited the activation of HSC through the inhibition of the TGF-β and PDGF pathways.

Enhanced effect of soluble transforming growth factor-beta receptor II and IFN-gamma fusion protein in reversing hepatic fibrosis

Objective

To examine the in vivo anti-fibrotic effect of rat soluble transforming growth factor β receptor II (RsTβRII) and IFN-γ fusion protein (RsTβRII-IFN-γ) in rat hepatic fibrosis model.

Methods

Model rats were divided into five groups and treated i.m. for 8 weeks: 1) fibrotic model group (each rat, 100 μl of 0.9% NaCl day^-1); 2) RsTβRII-IFN-γ treatment group (each rat, 0.136 mg· day^-1); 3) IFN-γ treatment group (each rat, 7.5 MU· day^-1); 4) RsTβRII treatment group (each rat, 0.048 mg· day^-1); and 5) mixture of IFN-γ and RsTβRII treatment group (each rat, IFN-γ 7.5 MU· day^-1+ RsTβRII 0.048 mg· day^-1). After treatment, hepatic fibrogenesis was evaluated by histopathological analysis and measurement of collagen III, α-smooth muscle actin (α-SMA), TGF-β1, TGF-βRII and their mRNA.

Results

Immunohistochemistry, Western blot and real-time RT-PCR showed that RsTβRII-IFN-γ treatment significantly inhibited liver expression of collagen III, α-SMA, TGF-β1 and TGF-βRII at both protein and mRNA levels. Histopathological analysis also showed that the enhanced anti-fibrotic effects were achieved in model rats treated with RsTβRII-IFN-γ.

Conclusion

Our results confirmed that RsTβRII-IFN-γ has the enhanced effects in reversing hepatic fibrosis.

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.

Interferon alpha increases metalloproteinase-13 gene expression through a polyomavirus enhancer activator 3-dependent pathway in hepatic stellate cells

BACKGROUND/AIMS

To determine the effects of IFNalpha on MMP-13 gene expression in primary culture of hepatic stellate cells.

METHODS

We measured MMP-13 mRNA, MMP-13 protein, MMP-13 luciferase activity, binding of AP1 and PEA3 to DNA, and binding of PEA3 to Jak1 and Stat1.

RESULTS

IFNalpha increased MMP-13 mRNA, MMP-13 protein, and luciferase activity in cells transfected either with a luciferase plasmid driven by the MMP-13 promoter or with the same plasmid in which the AP1 binding site has been mutated. IFNalpha induced the binding of nuclear proteins to a radiolabeled PEA3 probe, but not to a AP1 probe. Supershift assays demonstrated that PEA3 and Stat1 are implicated in the formation of this complex. Immunoprecipitation assays showed that PEA3 interacts physically with Stat1 and that IFNalpha treatment increases this interaction. Downregulation of PEA3 or JAK1 with appropriated siRNAs or mutation of the PEA3 binding site in the MMP-13 promoter abrogated the effects of IFNalpha on MMP-13 gene expression. Finally, IFNalpha induced the binding of PEA3 to JAK1, as well as PEA3 tyrosine and serine phosphorylation.

CONCLUSIONS

IFNalpha determines the binding of PEA3 to JAK1 and its tyrosine phosphorylation. Activated PEA3 binds to MMP-13 promoter and activates its expression.

Enhanced actions of insulin-like growth factor-I and interferon-alpha co-administration in experimental cirrhosis

BACKGROUND

Cirrhosis is a diffuse process of hepatic fibrosis and regenerative nodule formation. The liver is the major source of circulating insulin-like growth factor-I (IGF-I) whose plasma levels are diminished in cirrhosis. IGF-I supplementation has been shown to induce beneficial effects in cirrhosis, including antifibrogenic and hepatoprotective effects. On other hand, interferon-alpha (IFN-alpha) therapy seems to suppress the progression of hepatic fibrosis.

AIMS

The aim of this study was to investigate the effect of the co-administration of IGF-I+IFN-alpha to Wistar rats with CCl(4)-induced cirrhosis, exploring liver function tests, hepatic lipid peroxidation and histopathology.

METHODS

The mechanisms underlying the effects of these agents were studied by reverse transcription-polymerase chain reaction, determining the expression of some factors [hepatocyte growth factor (HGF), transforming growth factor-beta (TGF-beta), alpha-smooth muscle actin, collagen, tissular inhibitor of metalloproteinases-1 and pregnane X receptor (PXR)] involved in fibrogenesis, fibrolysis and/or hepatoprotection.

RESULTS

Both IGF-I and IFN-alpha exerted significant effects on fibrogenesis. IGF-I significantly increased serum albumin and HGF whereas IFN-alpha-therapy did not. The inhibition of TGF-beta expression was only observed by the effect of IFN-alpha-therapy. In addition, only the co-administration of IGF-I and IFN-alpha was able to increase the PXR. The combined therapy with both factors improved liver function tests, hepatic lipid peroxidation and reduced fibrosis, inducing a relevant histological improvement, reducing fibrosis and recovering hepatic architecture.

CONCLUSION

The co-administration IGF-I+IFN enhanced all the beneficial effects observed with each factor separately, showing an additive action on histopathology and PXR expression, which is involved in the inhibition of fibrogenesis.

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.

The effects of N-acetylcysteine on bile duct ligation-induced liver fibrosis in rats

Stellate cells are activated by free radicals, and synthesize collagen. N-acetylcysteine (NAC) is a precursor of reduced glutathione and a potent scavenger of hydroxyl radicals and has potential antifibrotic effects. We aimed to test the effects of NAC on bile duct ligation (BDL) induced liver damage in rats. Forty-seven Wistar rats were divided into 5 groups: group 1, BDL+NAC (n=10); group 2, BDL (n=10); group 3, sham+NAC (n=10); group 4, sham (n=10); and group 5, control group (n=10). NAC (50 micromol/kg per day) or saline of single doses were administered intraperitoneally for 28 days. Serum biochemical and liver oxidative stress parameters were studied. Liver collagen level was determined by the method of Lopez de Leon and Rojkind. Liver slides were stained by hematoxylin and eosin and Masson trichrome\Gomory reticulum staining. Aspartate aminotransferase (AST) and alkaline phosphatase levels in the BDL+NAC group were lower than the BDL group and were higher than the control groups (all P< .001). Malondialdehyde, luminal, and glutathione levels in group 1 were lower than the BDL group (P= .01, P= .002, and P< .001) and higher than the control groups (all P< .001). NAC had no effect on alanine aminotransferase (ALT), gammaglutamyl transferase, bilirubin, albumin, or lucigenin levels. Liver collagen levels were higher in the BDL groups (P< .001); however, NAC had no effect on the collagen levels. The BDL groups showed stage 3 fibrosis; all the control groups were normal. NAC improved some biochemical parameters (AST, alkaline phosphatase) and oxidative stress parameters (malondialdehyde, luminol, glutathione) in the BDL model. NAC was found to be effective on cholestasis-induced hepatotoxicity. However, NAC was inefficient as an antifibrotic agent within a 1-month period of administration in the BDL model.

Interferon-beta reduces the mouse liver fibrosis induced by repeated administration of concanavalin A via the direct and indirect effects

Type I interferons (IFNs), IFN-alpha and IFN-beta, are widely used for treating chronic hepatitis C. Although retrospective studies have suggested that type I IFNs have direct antifibrotic effects, little is known about these mechanisms. The present study was designed to clarify the preventive mechanisms of type I IFNs in the progression of fibrosis for the establishment of a more effective therapy. A murine fibrosis model comprising immunological reactions was induced by the administration of concanavalin A (0.3 mg/body) into mice once a week for 4 weeks. Liver injury and the degree of fibrosis were determined by measuring the serum alanine aminotransferase activities and liver hydroxyproline contents with or without IFN-beta pretreatment. IFN-beta suppressed the hepatocellular injury and increased the hydroxyproline content induced by repeated concanavalin A injections, but had no effect on established fibrosis. Furthermore, IFN-beta reduced the expressions of transforming growth factor-beta, basic fibroblast growth factor, collagen type I A2 and tissue inhibitor of metalloproteinase 1 messenger RNAs, which are related to the progression of liver fibrosis. The IFN-beta reduced the liver injury and fibrosis induced by immunological reactions. These data suggest that type I IFNs suppress the progression of cirrhosis through inhibition of repeated hepatocellular injury and/or factors that promote the liver fibrosis induced by hepatitis virus infection.

Blockade of renin-angiotensin system in antifibrotic therapy

Recent studies have shown that the renin-angiotensin system (RAS) plays a pivotal role in liver fibrosis. An intrahepatic RAS is expressed in chronically damaged livers, and angiotensin-II (AT-II) reportedly stimulates contraction and proliferation of the activated hepatic stellate cells (Ac-HSC), and increases the transforming growth factor-beta (TGF-beta) expression through angiotensin type-I receptors (AT1-R). Some studies have demonstrated that the clinically used angiotensin-converting enzyme (ACE) inhibitor (ACE-I), and AT1-R blockers (ARB) significantly attenuated experimental liver fibrosis along with suppression of the Ac-HSC and hepatic TGF-beta expression. Angiotensin-II also stimulates the tissue inhibitor of metalloproteinases-1 (TIMP-1) in a dose- and time-dependent manner via protein kinase-C as an intracellular signaling cascade in the Ac-HSC, and these effects are completely suppressed by ARB. Combination treatment with low-dose interferon (IFN) and ACE-I exerts a stronger inhibitory effect than either single agent on its own. In humans it has been reported that ARB markedly improved the liver fibrosis score and TGF-beta expression in patients with chronic hepatitis C and non-alcoholic steatohepatitis. Serum fibrosis markers also significantly improved by treatment with low-dose IFN and ACE-I in patients with chronic hepatitis C, refractory to IFN monotherapy. Collectively, these data suggest that the interaction between AT-II and AT1-R plays a pivotal role in liver fibrosis development. Because both ACE-I and ARB are widely used in clinical practice without serious side-effects, these drugs in combination with IFN may provide a new strategy for antifibrosis therapy.

Native Human IFN-αIs a More Potent Suppressor of HDF Response to Profibrotic Stimuli Than Recombinant Human IFN-α

Interferon-alpha(IFN-alpha) inhibits fibroblast proliferation, differentiation into myofibroblasts, and extracellular matrix synthesis, which are key events during both normal wound repair and fibrotic lesion formation. Unlike recombinant human IFN-alpha (rHuIFN-alpha), a native human IFN-alpha (nHuIFN-alpha) consists of several IFN-alpha subtypes and traces of other cytokines produced by the Sendai virus-stimulated human leukocytes. This study compares the antifibrotic effect of nHuIFN-alpha and rHuIFN-alpha in normal human dermal fibroblasts (HDFs). Treatment of HDF culture with nHuIFNA-alpha markedly affects HDF viability, whereas different rHuIFN-alpha subtypes show various effects. Two of twelve rHuIFN-alpha subtypes (IFN-alpha B2 and IFN-alpha K) significantly reduce cell viability of HDFs compared with nontreated HDFs. However, nHuIFN-alpha significantly reduces HDF cell viability in comparison to both nontreated cells and cells treated with rHuIFN-alpha. The 50% inhibitory concentration (IC(50)) varied 10-fold between nHuIFN-alpha and rHuIFN-alpha (1,103 IU/mL and 10,762 IU/mL, respectively). The impact on procollagen type I mRNA synthesis level is comparable at low doses of IFN (100 and 500 IU/mL), whereas at the dose of 1,000 IU/mL, nHuIFN-alpha shows higher repression of collagen type I gene than does rHuIFN-alpha. Both, nHuIFN-alpha and rHuIFN-alpha antagonize the effect of exogenous transforming growth factor-beta (TGF-beta) and interleukin-4 (IL-4) as measured by the alpha-smooth muscle actin (alpha -SMA) and procollagen type I mRNA level, but the effect of nHuIFN-alpha is more pronounced. This study suggests that nHuIFN-alpha is a more potent suppressor of the HDF response to profibrotic stimuli than rHuIFN-alpha, probably because of the synergism between different IFN-alpha subtypes and antifibrotic cytokines and factors.

Rat liver fibrosis regresses better with pegylated interferon alpha2b and ursodeoxycholic acid treatments than spontaneous recovery

BACKGROUND/AIMS

Fibrosis and cirrhosis are common complications of chronic liver diseases. An imbalance between fibrogenesis and fibrolysis results in scarring of the liver parenchyma. We aimed to investigate the possible antifibrotic effectiveness of a newly modified interferon molecule peginterferon alpha2b (PEG-IFNalpha2b) which has better antiviral activity, and ursodeoxycholic acid (UDCA).

METHODOLOGY

Liver fibrosis was established on 60 male Sprague Dawley rats with CCl4 in 12 weeks. After cessation of CCl4 Group I was left for spontaneous recovery. Group II was treated with PEG-IFN 1.5 microg/kg/week, Group III with UDCA 25 mg/kg/day and Group IV with combination of both drugs. All rats were killed at week 16. Histopathologic fibrosis scores, tissue hydroxyproline, TIMP-1 and MMP-13 levels were determined. Hepatic stellate cell apoptosis was detected by dual staining with TUNEL technique and anti-alpha smooth muscle actin.

RESULTS

Fibrosis scores were lower in Group II, III and IV than Group I (p<0.05 for group I vs. II and III; p<0.01 for group I vs. IV). Tissue hydroxyproline levels were significantly decreased in Group II, III and IV when compared to Group I (p<0.05 for group I vs. II, p<0.01 for group I vs. III and IV). Lower liver TIMP-1 and higher MMP-13 levels were measured in Group II, III, and Group IV than Group I (p<0.01 for TIMP-1 and p<0.01, for MMP). Activated HSC apoptosis was significantly increased in Group II, III and IV when compared to Group I (p<0.01, for all). There was significantly higher apoptosis in Group II than Group III and IV (p<0.01).

CONCLUSION

Treatment with both PEG-IFNalpha2b and UDCA improved CCl4 induced rat liver fibrosis. Significantly higher effects were obtained using these agents in combination.

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.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Effect of IFN-α on CC14-Induced Fibrosis of the Liver and Immune Status in Mice of Different Age

In young, adult, and old mice fibrosis was induced by administration of CC1(4) and treated with IFN-alpha; liver fibrosis was evaluated by morphometry of argyrophilic fibers, immune status by the splenocyte proliferative response. minimum immunosuppression and maximum antifibrotic effect were observed in young mice, while adult mice exhibited pronounced immunotoxicity and weak response to interferon therapy.

Combination of interferon-beta and angiotensin-converting enzyme inhibitor, perindopril, attenuates the murine liver fibrosis development

Recent studies have revealed that both interferon (IFN) and angiotensin-converting enzyme inhibitor (ACE-I) exert an anti-fibrotic effect. The aim of this study was to examine the combined effect of the ACE-I and IFN on the murine hepatic fibrosis development. A model of CCl(4)-induced hepatic fibrosis was used to assess the effect of the clinically used ACE-I, perindopril (PE), and IFN-beta. The PE and IFN were administered after 2-week treatment with CCl(4), and the hepatic indices of fibrosis were assessed at 8 weeks. Single treatment with either PE or IFN at the clinically available comparable doses significantly attenuated liver fibrogenesis associated with suppression of the hepatic hydroxyproline and serum fibrosis markers. The number of alpha-smooth muscle actin-positive cells, and the hepatic alpha1(I)-procollagen mRNA were also markedly inhibited. The inhibitory effect of PE was more potent than IFN, and the combination treatment with PE and IFN almost completely attenuated liver fibrosis development. In vitro, the angiotensin-II (AT-II) type 1 receptor blocker and IFN suppressed the AT-II-induced proliferation and alpha1(I)-procollagen mRNA expression of the activated hepatic stellate cells. The combination treatment of the clinically used PE and IFN may provide a new strategy for anti-liver fibrosis therapy.

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.

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.

Adenovirus-mediated gene transfer of interferon alpha inhibits hepatitis C virus replication in hepatocytes

Recently we reported that on-site interferon (IFN)-alpha production in the liver using an adenovirus vector can achieve a substantial confinement of IFN-alpha in the target organ and can improve liver fibrosis in a rat liver cirrhosis model. However, the major therapeutic effect of IFN for hepatitis C virus (HCV)-associated liver diseases is its antiviral effect on HCV. As a prelude to the in vivo HCV infection experiment using a primate animal model, here we examined the antiviral effect of IFN-alpha gene transfer into HCV-positive hepatocytes in vitro. The non-neoplastic human hepatocyte cell line PH5CH8 was inoculated with HCV-positive serum. Successful in vitro HCV replication and thus the validity of this model was confirmed by a strong selection for HCV variants determined by sequence analysis of the hypervariable region and an increase of HCV RNA estimated by real time TaqMan RT-PCR. One day after the inoculation of HCV, PH5CH8 cells were infected with adenoviral vectors encoding human IFN-alpha cDNA. HCV completely disappeared 9 days after the adenoviral infection, which is linked to the increase of 2('),5(')-oligoadenylate synthetase activity, suggesting that IFN-alpha produced by gene transfer effectively inhibits HCV replication in hepatocytes. This study supports the development of IFN-alpha gene therapy for HCV-associated liver diseases.

Adenovirus-mediated gene transfer of interferon alpha improves dimethylnitrosamine-induced liver cirrhosis in rat model

Several lines of evidence suggest that interferon (IFN)-alpha is effective in suppression of liver cirrhosis (LC) as well as hepatitis C virus (HCV) infection, which is a major cause of LC in Japan. However, IFN-alpha often causes systemic toxicity such as flu-like symptoms, which precludes the IFN-alpha dose escalation required for clinical efficacy. Since IFN-alpha is rapidly degraded in the blood circulation, only a small amount of subcutaneously injected IFN-alpha protein can reach the target organ, the liver. It is expected that on-site IFN-alpha production in the liver overcomes the limitation of the conventional parenteral IFN-alpha administration. An adenovirus vector expressing the rat IFN-alpha gene (AxCA-rIFN) was injected intravenously into rats with dimethylnitrosamine-induced LC. While the subcutaneous IFN-alpha protein injection led to a transient elevation of the cytokine both in the liver and serum, the vector-mediated IFN-alpha gene transduction induced a significant amount of IFN-alpha detected in the liver but not in the serum. The injection of AxCA-rIFN prevented the progression of the rat LC, and improved the survival rate of the treated rats. Although no significant toxicity was noted in the animals, we showed that IFN-alpha gene expression in the liver can be efficiently downregulated by the Cre/loxP-mediated shut-off system, in case the IFN-alpha overdose becomes a problem. The study suggested for the first time the advantage and feasibility of IFN-alpha gene therapy for LC.

In vivo inefficiency of pentoxifylline and interferon-alpha on hepatic fibrosis in biliary-obstructed rats: assessment by tissue collagen content and prolidase activity

BACKGROUND AND AIM

To evaluate the possible antifibrotic effects of two drugs, pentoxifylline (PTX) and interferon (IFN)-alpha as well as their combination, on a bile-duct-ligated rat hepatic fibrosis model.

METHODS

Bile ducts of 34 female Wistar rats were ligated, and 24 bile ducts were sham operated. Bile-duct-ligated rats were divided into four groups, in which either sterile saline, IFN-alpha (100 000 IU/3 days a week), PTX (50 mg/kg/day) or IFN-alpha + PTX were administered. Sham-operated rats were treated at the same doses. On the 28th day, rats were decapitated to obtain blood for the measurements of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT) and bilirubins. Serum prolidase was assayed at the beginning and at the end of the study by the modified Chinard's colorimetric method. Liver prolidase was assayed after tissue homogenization. Liver collagen content was determined by the dye elution method described by Lopez de Leon. Morphometric-densitometric measurements of hepatic fibrosis were quantified by computerized image analysis.

RESULTS

The AST, ALT, ALP, GGT and bilirubins, liver prolidase enzyme activity, collagen content and hepatic collagen surface density were found to be increased in bile-duct-ligated rats on day 28. There was no statistically significant recovery or even a change in collagen turnover rate in rats treated with alternate regimens applied in the study (P > 0.05).

CONCLUSION

Pentoxifylline, IFN-alpha and their combination have no beneficial effect on experimental fibrosis induced by biliary obstruction.

Expression of exogenous rat collagenase in vitro and in a rat model of liver fibrosis

AIM: The present study was conducted to test the hypothesis that the introduction of the collagenase gene into tissue culture cells and into a rat model of liver fibrosis would result in the expression of enzymatically active product.

METHODS: FLAG-tagged full-length rat collagenase cDNA was PCR amplified and cloned into a mammalian expression vector. NIH3T3 cells were then transiently transfected with this construct. Expression of exogenous collagenase mRNA was assessed by RT-PCR, and the exogenous collagenase detected by Western blotting using anti-FLAG monoclonal antibody. Enzymatic activity was detected by gelatin zymography. To determine the effects of exogenous collagenase production in vivo, the construct was bound to glycosyl-poly-L-lysine and then transduced into rats that had developed liver fibrosis as a result of CCl₄ plus ethanol treatment. The hepatic expression of the construct and its effect on the formation of liver fibrosis were demonstrated using RT-PCR and immunohistochemistry.

RESULTS: It was found that exogenously expressed rat collagenase mRNA could be detected in NIH3T3 cells following transfection. Enzymatically active collagenase could also be detected in the culture medium. The recombinant plasmid was also expressed in rat liver after in vivo gene transfer. Expression of exogenous rat collagenase correlated with decreased deposition of collagen types I and III in the livers of rats with experimentally induced liver fibrosis.

CONCLUSION: The expression of active exogenous rat collagenase could be achieved in vitro and in vivo. It was suggested that in vivo expression of active exogenous collagenase may have therapeutic effects on the formation of liver fibrosis.

Selective down-regulation of c-jun gene expression by pentoxifylline and c-jun antisense interrupts platelet-derived growth factor signaling: pentoxifylline inhibits phosphorylation of c-Jun on serine 73

Platelet-derived growth factor (PDGF) signals through several pathways, including mitogen-activated protein (MAP) kinase, Jun kinase, and C kinase, and stimulates proliferation of fibroblasts. Pentoxifylline inhibits PDGF-driven proliferation of fibroblasts. We have reported that pentoxifylline did not inhibit binding of PDGF to its specific cell-surface receptors or PDGF receptor phosphorylation. In this study, we investigated the effect of PDGF on the expression of c-fos and c-jun, because c-fos and c-jun form activator protein-1 complexes that stimulate genes involved in proliferation. We determined whether pentoxifylline would alter the expression of c-fos and c-jun. Our results indicate that PDGF induced the expression of both c-fos and c-jun. Pentoxifylline effectively reduced c-jun gene expression, which had been up-regulated by PDGF, but did not alter c-fos gene expression. The lack of effect on c-fos supports other studies from this laboratory, which indicate that pentoxifylline did not inhibit PDGF activation of MAP kinase. Treatment of fibroblasts with a phosphothioate c-jun antisense oligodeoxynucleotide reduced the levels of c-Jun protein and blocked PDGF-stimulated proliferation, suggesting a critical role for c-jun in PDGF-mediated proliferation. Combination of pentoxifylline and c-jun antisense suggested that they were likely inhibiting PDGF-stimulated proliferation at a single site in the PDGF signaling pathway. These results suggest that pentoxifylline inhibits PDGF-stimulated proliferation by selectively decreasing c-jun expression. To further define the mechanism of action of pentoxifylline, we assessed the effect of pentoxifylline on c-Jun and phosphorylated c-Jun immunoreactivity in cells treated with PDGF and cells that were transfected with wild-type c-jun plasmid using immunocytochemistry and Western blot analyses, and our results indicate that pentoxifylline inhibited phosphorylation of c-Jun on serine 73.

Increased oxidative stress in dimethylnitrosamine-induced liver fibrosis in the rat: effect of N-acetylcysteine and interferon-alpha

Oxidative stress may represent a common link between chronic liver damage and hepatic fibrosis. Antioxidants and interferon seem to protect against hepatic stellate cell (HSC) activation and liver fibrosis. This study evaluated (1) the effect of the profibrotic agent dimethylnitrosamine (DMN) on the hepatic oxidative balance in the rat; (2) the role played by the antioxidant agent N-acetylcysteine (NAC); and (3) the antifibrotic effects of two different types of interferon-alpha: recombinant alpha-2b (rIFN-alpha) and leukocyte alpha (LeIFN-alpha). Five groups of rats received: (1) saline; (2) DMN; (3) DMN + NAC; (4) DMN + rIFN-alpha; and (5) DMN + LeIFN-alpha. Oxidative balance was evaluated by hepatic glutathione, TBARs, protein carbonyl, and sulfhydryl determination. Fibrosis was determined by hepatic hydroxyproline content and fibronectin (FN) staining (immunohistochemistry). DMN rats showed a diffuse FN deposition, an impaired oxidative balance, and higher hepatic hydroxyproline levels compared to that of controls. NAC administration significantly reduced FN deposition, increased hepatic glutathione, and decreased TBARs and protein carbonyls. Administration of IFN-alpha exerted different effects according to the type used. Both IFNs decreased FN deposition; however, LeIFN-alpha significantly improved histology and oxidative parameters compared to those of untreated DMN and rats treated with rIFN-alpha. This study shows the role of free radicals in this model of hepatic fibrosis; the protective effect of NAC against liver fibrosis; and the antifibrotic effect exerted by IFN-alpha (particularly LeIFN-alpha) independent of its antiviral activity.

Changes in histological lesions and serum fibrogenesis markers in chronic hepatitis C patients non-responders to interferon alpha

BACKGROUND/AIMS

The aim of this study was to evaluate the changes in histological lesions and serum N-terminal peptide of type III procollagen (PIIINP) and hyaluronate (HA) levels in virologic non-responder patients treated by Interferon alpha (IFNalpha).

METHODS

We enrolled 183 patients treated by IFNalpha and 56 controls, all with paired biopsy specimens. Yearly liver fibrosis progression was estimated before and during a follow-up of 1 year.

RESULTS

By contrast to sustained responders, non-responders (n = 105) did not achieve improvement of histological scores after therapy. Their yearly fibrosis progression rate was similar before and during follow-up (0.18, 95%CI: 0.16-0.20, vs 0.26 (95%CI: 0.12-0.40) fibrosis units/year, NS), and was not different in controls (0.17, 95%CI: 0.06-0.27). The levels of PIIINP and hyaluronate (HA) remained unchanged during follow-up. Histological improvement was observed for the second biopsy in 25% of non-responders, but also in 23% of controls. This improvement was not correlated with decrease of ALT level, viral load, PIIINP, or HA.

CONCLUSIONS

Our results suggest that IFNalpha therapy is unable to decrease PIIINP or HA levels and cannot improve the histological outcome in virologic non-responder patients. The histological improvement observed in a subset of patients may be linked to sample fluctuation or lack of reproducibility of histological scores.

Hepatic fibrosis. Pathogenesis and principles of therapy

There has been great progress made in our understanding of the cellular mechanisms of hepatic fibrosis. The recognition that the hepatic stellate cell, (formerly know as lipocyte, Ito, or fat-storing cell), played a central role in the fibrotic response was key to our understanding. Stellate cells undergo a process known as activation, in response to any insult. Activation is a broad phenotypic response, characterized by distinct functional changes in proliferation, fibrogenesis, contractility, cytokine secretion, and matrix degradation. Insights gained into the molecular regulations of stellate cell activation may lead to new antifibrotic therapies, which may reduce morbidity and mortality in patients with chronic liver injury.

Effect of interferon-alpha on experimental septal fibrosis of the liver - study with a new model

Interferon-alpha is used in antiviral therapy in humans, mainly for viral hepatitis B and C. An anti-fibrotic effect of interferon has been postulated even in the absence of anti-viral response, which suggests that interferon directly inhibits fibrogenesis. Rats infected with the helminth Capillaria hepatica regularly develop diffuse septal fibrosis of the liver, which terminates in cirrhosis 40 days after inoculation. The aim of this study was to test the anti-fibrotic effect of interferon in this experimental model. Evaluation of fibrosis was made by three separate methods: semi-quantitative histology, computerized morphometry and hydroxyproline measurements. Treatment with interferon-alpha proved to inhibit the development of fibrosis in this model, especially when doses of 500,000 and 800,000 IU were used for 60 days. Besides confirming the anti-fibrotic potential of interferon-alpha on a non-viral new experimental model of hepatic fibrosis, a clear-cut dose-dependent effect was observed.

Animal experiment and clinical study of effect of gamma-interferon on hepatic fibrosis

AIM

To evaluate the antifibrotic effect of different doses of recombinant human Gamma-Interferon (IFN-gamma) in two rat models of hepatic fibrosis, and to observe its effect on moderate chronic hepatitis B virus fibrosis.

METHODS

Hepatic fibrosis was successfully induced in 150 and 196 rats by subcutaneous injection of carbon tetrachloride (CCl4) and intraperitoneal injection of dimethylnitrosamine (DMN), respectively. Each of the two model groups was divided into: (1) fibrotic model group; (2) colchicine treatment group (0.1 mg/kg/day, gastrogavage for 8 weeks); (3) high-dose IFN-gamma group (15 MU/kg per day, i.m. for 8 weeks); (4) medium-dose IFN-gamma group (5 MU/kg daily, i.m. for 8 weeks); and (5) Y low-dose IFN-gamma group (1.67 MU/kg daily, i.m. for 8 weeks). Another group of 10 rats without any treatment was used as normal controls. At the end of the experiment, semi-quantitative histopathological scores of inflammation and fibrosis, liver alpha smooth muscle actin (alpha-SMA) expression level, liver hydroxyl proline content and serum hyaluronic acid levels were compared. And 47 medium chronic hepatitis B viral fibrosis patients were studied. They were given IFN-gamma treatment, 100 MU/day i.m. for the first three months and 100 MU qod i.m. for the next six months. Semi-quantitative pathological scores of inflammation and fibrosis and serum hepatic fibrosis indices were compared within the 9 months.

RESULTS

In animal experiment, the pathological fibrosis scores and liver hydroxyl proline content were found to be significantly lower in rats treated with different doses of IFN-gamma as compared with rats in fibrotic model group induced by either CCl4 or DMN, in a dose-dependent manner. For CCl4-induced model, pathological fibrosis scores in high, medium and low doses IFN-gamma groups were 5.10 +/- 2.88, 7.70 +/- 3.53 and 8.00 +/- 3.30, respectively, but the score was 14.60 +/- 7.82 in fibrotic model group. Hydroxyl proline contents were 2.83 +/- 1.18, 3.59 +/- 1.22 and 4.80 +/- 1.62, in the three IFN-gamma groups, and 10.01 +/- 3.23 in fibrotic model group. The difference was statistically significant (P<0.01). Similar results were found in DMN-induced model. Pathological fibrosis scores were 6.30 +/- 0.48, 8.10 +/- 2.72 and 8.30 +/- 2.58, in high, medium and low doses IFN-gamma groups, and 12.60 +/- 3.57 in fibrotic model group. Hydroxyl proline contents were 2.72 +/- 0.58, 3.14 +/- 0.71 and 3.62 +/- 1.02, in the three IFN-gamma groups, and 12.79 +/- 1.54 in fibrotic model group. The difference was statistically significant (P<0.01). Serum hepatic fibrosis indices decreased significantly in the 47 patients after IFN-gamma treatment (HA: 433.38 +/- 373.00 vs 281.57 +/- 220.48; LN: 161.22 +/- 41.02 vs 146 +/- 35 +/- 44. 67; PC III: 192.59 +/- 89.95 vs 156.98 +/- 49.22; C-I: 156.30 +/- 44.01 vs 139.14 +/- 34.47) and the differences between the four indices were significant (P <0.05). Thirty-three patients received two liver biopsies, one before and one after IFN-gamma treatment. In thirty of 33 patients IFN-gamma had better effects according to semi-quantitative pathological scores (8.40 +/- 5.83 vs 5.30 +/- 4.05, P<0.05).

CONCLUSION

All the three doses of IFN-gamma are effective in treating rat liver fibrosis induced by either CCl4 or DMN, the higher the dose, the better the effect. And IFN-gamma is effective for patients with moderate chronic hepatitis B viral fibrosis.

[Experimental cirrhosis induced by carbon tetrachloride inhalation: adaptation of the technique and evaluation of lipid peroxidation]

BACKGROUND

Long-term administration of carbon tetrachloride is an accepted experimental model to produce hepatic fibrosis. Oxidative stress has been postulated as a major molecular mechanism involved in carbon tetrachloride hepatotoxicity, where the reactive oxygen species play an important role in the pathogenesis of liver fibrosis.

AIMS

This study was conducted to evaluate the effectiveness of an experimental model of hepatic cirrhosis induced by carbon tetrachloride inhalation as well as the importance of lipid peroxidation and the characteristics of the ascitic fluid in this model.

METHODS

At first the hepatic histologic findings were assessed using the hematoxilineosin technique in different moments of carbon tetrachloride inhalation (5th, 7th, 9th, 12th weeks). Later, at the end of 15 weeks of the study the rats were divided in three groups (control; control + phenobarbital; and carbon tetrachloride + phenobarbital) for lipid peroxidation, ascitic fluid and histologic characteristics evaluation. For the lipid peroxidation analysis, thiobarbituric acid and QL techniques were used. Cytologic and bacteriologic parameters were analysed in the ascitic fluid.

RESULTS

Cirrhosis was established in 100% of carbon tetrachloride rats between the 12th and 15th weeks with an elevation in the lipid peroxidation carbon tetrachloride rats' livers. Ascitic fluid infection was observed in one of seven rats who has developed ascites.

CONCLUSIONS

The carbon tetrachloride inhalation method developed in this study is effective in cirrhosis induction and ascites formation, and the carbon tetrachloride cirrhosis physiopathogenesis is probably related to the oxidative stress installation.

Chronic administration of interferon-a decreases blood pressure and heart rate in rats

We studied the effects of interferon-alpha on rat cardiovascular system. Intravenous administration of intron-A in a dose of 100,000 IU/kg for 3 days led to a permanent and statistically significant decrease in blood pressure (on days 2 and 3) and reduction in heart rate. These effects were not associated with changes in baroreflex regulation of the cardiovascular system.

The cell and molecular biology of hepatic fibrogenesis. Clinical and therapeutic implications

Much has been learned in the past 2 decades about the cellular and molecular mechanisms underlying hepatic fibrogenesis and about potential therapeutic approaches in patients with liver disease. The central event in fibrogenesis seems to be the activation of hepatic stellate cells. Stellate cell activation is characterized by several important features, including enhanced matrix synthesis and a prominent contractile phenotype, processes that probably contribute to the physical distortion and dysfunction of the liver in advanced disease. It is important to emphasize that the factors controlling activation are multifactorial and complex. The extracellular matrix is a dynamic, active constituent of the fibrogenic response and undergoes active remodeling, including synthesis and degradation. Effective therapy for hepatic fibrogenesis will probably also be multifactorial, based on the basic mechanisms underlying the fibrogenic process. The most effective therapies will probably be directed at the stellate cell. Approaches that address matrix remodeling (i.e., by enhancing matrix degradation or by inhibiting factors that prevent matrix breakdown) may be effective.

Resolution of chronic delta hepatitis after 12 years of interferon alfa therapy

Chronic delta hepatitis is an uncommon but severe form of chronic viral hepatitis for which there is currently no satisfactory therapy. A patient with chronic delta hepatitis was treated with interferon alfa, 5 million units daily for 12 years. Serial serum samples were tested for routine liver tests and selected samples for quantitative levels of hepatitis B surface antigen (HBsAg) and hepatitis delta virus RNA. Liver biopsies were performed before, during, and after an initial 1-year course of therapy and again after 3 and 10 years of continuous therapy. With initiation of interferon therapy, serum aminotransferase levels decreased to normal range, became abnormal again when the dose was reduced, and increased to pretreatment levels when therapy was stopped. With reinstitution and prolonged therapy, aminotransferase levels became persistently normal; after several years, both hepatitis delta virus RNA and serum HBsAg became undetectable. Liver biopsy, which initially revealed cirrhosis, showed gradual improvement in inflammatory and fibrosis scores and, after 10 years, no abnormalities or fibrosis. Therapy was stopped, and the patient remained free of evidence of infection. In conclusion, long-term therapy with interferon alfa in high doses led to resolution of chronic delta hepatitis, disappearance of hepatitis delta and B virus markers, and improvement in fibrosis.

Liver fibrogenesis and the role of hepatic stellate cells: new insights and prospects for therapy

Hepatic fibrosis is a wound-healing response to chronic liver injury, which if persistent leads to cirrhosis and liver failure. Exciting progress has been made in understanding the mechanisms of hepatic fibrosis. Major advances include: (i) characterization of the components of extracellular matrix (ECM) in normal and fibrotic liver; (ii) identification of hepatic stellate cells as the primary source of ECM in liver fibrosis; (iii) elucidation of key cytokines, their cellular sources, modes of regulation, and signalling pathways involved in liver fibrogenesis; (iv) characterization of key matrix proteases and their inhibitors; (v) identification of apoptotic mediators in stellate cells and exploration of their roles during the resolution of liver injury. These advances have helped delineate a more comprehensive picture of liver fibrosis in which the central event is the activation of stellate cells, a transformation from quiescent vitamin A-rich cells to proliferative, fibrogenic and contractile myofibroblasts. The progress in understanding fibrogenic mechanisms brings the development of effective therapies closer to reality. In the future, targeting of stellate cells and fibrogenic mediators will be a mainstay of antifibrotic therapy. Points of therapeutic intervention may include: (i) removing the injurious stimuli; (ii) suppressing hepatic inflammation; (iii) down-regulating stellate cell activation; and (iv) promoting matrix degradation. The future prospects for effective antifibrotic treatment are more promising than ever for the millions of patients with chronic liver disease worldwide.

Apoptosis and liver fibrosis: antifibrotic strategies

Hepatic fibrosis is a frequent response of the liver and is similar to parenchymal wound healing in other tissues. Apoptosis has been described in different models of liver fibrosis. Hepatic stellate cells are the main source of extracellular matrix. At present, one can speculate that inhibition of apoptosis is responsible for activation and proliferation of hepatic stellate cells. Thus, the inhibition of hepatic stellate cell apoptosis could be a target for antifibrotic strategies. Until now, no drugs have been clearly shown to be effective in reducing specifically the development of hepatic fibrosis. However, serious candidates are presently under studies in clinical trials, including especially alpha interferon and phosphatidylcholine.