Prevention of fibrosis reduces enzyme-altered lesions in the rat liver

Lipidomic-based investigation into the therapeutic effects of polyene phosphatidylcholine and Babao Dan on rats with non-alcoholic fatty liver disease

In recent years, with the improvement of people's living standards, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in the world. In this paper, the metabolic disorders in Sprague Dawley (SD) rats were induced by a choline-deficient, l-amino acid-defined (CDAA) diet. The therapeutic effects of polyene phosphatidylcholine (PPC) and Babao Dan (BBD) on NAFLD were observed. Lipidomic analysis was performed using ultra-high-performance liquid chromatography-Orbitrap MS, and data analysis and lipid identification were performed using the software LipidSearch. Both PPC and BBD can reduce lipid accumulation in the liver and improve abnormal biochemical indicators in rats, including reduction of triglycerides, total cholesterol, alanine transaminase and aspartate transaminase in serum. In addition, lipids in rat serum were systematically analyzed by lipidomics. The lipidomic results showed that the most obvious lipids with abnormal metabolism in CDAA diet-induced rats were glycerides (triglycerides and diacylglycerols), phospholipids and cholesterol esters. Both BBD and PPC partly reversed the disturbance to lipids induced by the CDAA diet. PPC may be more effective than BBD in alleviating NAFLD because it has a better effect on inhibiting the abnormal accumulation of lipids and reducing the inflammatory reaction in the body.

Glutathione Transferase P1-1 an Enzyme Useful in Biomedicine and as Biomarker in Clinical Practice and in Environmental Pollution

Glutathione transferase P1-1 (GSTP1-1) is expressed in some human tissues and is abundant in mammalian erythrocytes (here termed e-GST). This enzyme is able to detoxify the cell from endogenous and exogenous toxic compounds by using glutathione (GSH) or by acting as a ligandin. This review collects studies that propose GSTP1-1 as a useful biomarker in different fields of application. The most relevant studies are focused on GSTP1-1 as a biosensor to detect blood toxicity in patients affected by kidney diseases. In fact, this detoxifying enzyme is over-expressed in erythrocytes when unusual amounts of toxins are present in the body. Here we review articles concerning the level of GST in chronic kidney disease patients, in maintenance hemodialysis patients and to assess dialysis adequacy. GST is also over-expressed in autoimmune disease like scleroderma, and in kidney transplant patients and it may be used to check the efficiency of transplanted kidneys. The involvement of GSTP in the oxidative stress and in other human pathologies like cancer, liver and neurodegenerative diseases, and psychiatric disorders is also reported. Promising applications of e-GST discussed in the present review are its use for monitoring human subjects living in polluted areas and mammals for veterinary purpose.

Exogenous Administration of Low-Dose Lipopolysaccharide Potentiates Liver Fibrosis in a Choline-Deficient l-Amino-Acid-Defined Diet-Induced Murine Steatohepatitis Model

Various rodent models have been proposed for basic research; however, the pathogenesis of human nonalcoholic steatohepatitis (NASH) is difficult to closely mimic. Lipopolysaccharide (LPS) has been reported to play a pivotal role in fibrosis development during NASH progression via activation of toll-like receptor 4 (TLR4) signaling. This study aimed to clarify the impact of low-dose LPS challenge on NASH pathological progression and to establish a novel murine NASH model. C57BL/6J mice were fed a choline-deficient l-amino-acid-defined (CDAA) diet to induce NASH, and low-dose LPS (0.5 mg/kg) was intraperitoneally injected thrice a week. CDAA-fed mice showed hepatic CD14 overexpression, and low-dose LPS challenge enhanced TLR4/NF-κB signaling activation in the liver of CDAA-fed mice. LPS challenge potentiated CDAA-diet-mediated insulin resistance, hepatic steatosis with upregulated lipogenic genes, and F4/80-positive macrophage infiltration with increased proinflammatory cytokines. It is noteworthy that LPS administration extensively boosted pericellular fibrosis with the activation of hepatic stellate cells in CDAA-fed mice. Exogenous LPS administration exacerbated pericellular fibrosis in CDAA-mediated steatohepatitis in mice. These findings suggest a key role for LPS/TLR4 signaling in NASH progression, and the authors therefore propose this as a suitable model to mimic human NASH.

Preclinical models of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) can manifest as non-alcoholic fatty liver (NAFL) or non-alcoholic steatohepatitis (NASH). NASH is often associated with progressive fibrosis which can lead to cirrhosis and hepatocellular carcinoma (HCC). NASH is increasing as an aetiology for end-stage liver disease as well as HCC. There are currently no approved therapies for NASH. A major barrier to development of therapeutics for NASH is the lack of preclinical models of disease that are appropriately validated to represent the biology and outcomes of human disease. Many in vitro and animal models have been developed. In vitro models do not fully capture the hepatic and extrahepatic milieu of human NASH and large animal models are expensive and logistically difficult to use. Therefore, there is considerable interest in the development and validation of mouse models for NAFLD, including NASH. Several models based on varying genetic or dietary manipulations have been developed. However, the majority do not recreate steatohepatitis, strictly defined as the presence of hepatocellular ballooning with or without Mallory-Denk bodies, accompanied by inflammation in the presence of macrovesicular steatosis. Others lack validation against human disease. Herein, we describe the best practices in development of mouse models of NASH. We further review existing models and the literature supporting their use as a surrogate for human disease. Finally, data on models to evaluate protective genes are discussed. It is hoped that this review will provide guidance for the interpretation of data derived from mouse models and also for the development and validation of newer models.

An improved mouse model that rapidly develops fibrosis in non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is a progressive fibrotic disease, the pathogenesis of which has not been fully elucidated. One of the most common models used in NASH research is a nutritional model where NASH is induced by feeding a diet deficient in both methionine and choline. However, the dietary methionine-/choline-deficient model in mice can cause severe weight loss and liver atrophy, which are not characteristics of NASH seen in human patients. Exclusive, long-term feeding with a high-fat diet (HFD) produced fatty liver and obesity in mice, but the HFD for several months did not affect fibrosis. We aimed to establish a mouse model of NASH with fibrosis by optimizing the methionine content in the HFD. Male mice were fed a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) consisting of 60 kcal% fat and 0.1% methionine by weight. After 1–14 weeks of being fed CDAHFD, the mice were killed. C57BL/6J mice maintained or gained weight when fed CDAHFD, while A/J mice showed a steady decline in body weight (of up to 20% of initial weight). In both strains of mice, plasma levels of alanine aminotransferase increased from week 1, when hepatic steatosis was also observed. By week 6, C57BL/6J mice had developed enlarged fatty liver with fibrosis as assessed by Masson's trichrome staining and by hydroxyproline assay. Therefore, this improved CDAHFD model may be a mouse model of rapidly progressive liver fibrosis and be potentially useful for better understanding human NASH disease and in the development of efficient therapies for this condition.

Spontaneously hypertensive rats develop pronounced hepatic steatosis induced by choline-deficient diet: Evidence for hypertension as a potential enhancer in non-alcoholic steatohepatitis

AIM

  Patients with non-alcoholic steatohepatitis (NASH) frequently have many co-morbidities including essential hypertension, which is reported to increase vascular production of reactive oxygen species (ROS) and alter the hepatic anti-oxidant defense system. Since ROS play a role in the pathogenesis of NASH, it is hypothesized that hypertension modulates the hepatic oxidative status and influences the development of NASH. The aim of this study was to investigate the potential effects of hypertension on the progression of NASH.

METHODS

  Spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats as normotensive controls were fed choline-deficient (CD) diet for 5 weeks. Histological changes, messenger RNA (mRNA) expression and thiobarbituric acid reactive substances (TBARS) levels in the liver were assessed in each group.

RESULTS

  Choline-deficient diet led to pronounced hepatic steatosis in SHR with an 8-fold increase of the hepatic triglyceride content, while there was no significant increase in WKY. These changes in SHR were associated with significant reduction in the expression of mRNA for peroxisome proliferator activated receptor α, acyl-CoA oxidase, microsomal triglyceride transfer protein, and apolipoprotein B100. Consistent with the significant reduction of hepatic superoxide dismutase activity and marked downregulation of the gene expression of hepatic antioxidant enzymes, the hepatic TBARS level and the plasma level of alanine aminotransferase were only increased in SHR on CD diet.

CONCLUSIONS

  Spontaneously hypertensive rats receiving CD diet showed severe hepatic steatosis associated with reduction of hepatic anti-oxidant capacity, leading to increased hepatic oxidative stress and tissue damage. Accordingly, hypertension might have a potential effect on the progression of NASH.

Telmisartan improves nonalcoholic steatohepatitis in medaka (Oryzias latipes) by reducing macrophage infiltration and fat accumulation

We investigated the efficacy of the antihypertensive drug telmisartan (Tel) and the mechanisms underlying the progression from simple steatosis to nonalcoholic steatohepatitis (NASH) in a medaka (Oryzias latipes) NASH model. We used the NASH activity score (NAS) developed in humans to assess the histology of the medaka NASH model and found that NAS increased with time. Further, TUNEL-positive apoptosis hepatocytes were found in the medaka NASH model. Tel administration resulted in the increased expression of liver peroxisome proliferator-activated receptor-γ, carnitine palmitoyltransferase 1 and acyl-CoA oxidase 1 and decreased the number of 8-hydroxydeoxyguanosine-positive hepatocytes and the migration of macrophages positive for diastase-periodic-acid-Schiff. Medaka NAS was improved by Tel administration but fatty acid content was not affected. Tel reduced the infiltration of macrophages into the liver and ameliorated NASH pathology.

Immunotherapy for nonalcoholic steatohepatitis using the multiple cytokine production modulator Y-40138

AIM: To investigate the possible use of the multiple cytokine production modulator, Y-40138, as a novel immunotherapy in the rat nonalcoholic steatohepatitis (NASH) model.

METHODS: We allocated 6-wk-old male F344 rats to choline-supplemented, L-amino acid-defined (CSAA) diet (control group), CSAA diet + Y-40138 (control + Y-40138 group), choline-deficient, L-amino acid-defined (CDAA) diet (NASH group), or CDAA diet + Y-40138 (NASH + Y-40138 group). In each group, we measured the plasma alanine aminotransferase (ALT) levels, and the plasma and liver levels of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukin-10 (IL-10). Tissue specimens of phosphate buffered saline-perfused liver were subjected to hematoxylin and eosin staining, Azan staining, Sirius red staining, and immunohistochemical staining (for Kupffer cells and TNF-α). We then extracted Kupffer cells from the collagenase-perfused livers using the Percoll gradient centrifugation method, and measured the TNF-α levels in the supernatant (in vitro TNF-α production by Kupffer cells) using an enzyme-linked immunosorbent assay kit.

RESULTS: In comparison to the NASH group, serum ALT elevation was mild, production of serum and liver TNF-α and IFN-γ was inhibited, and IL-10 production was increased in the NASH + Y-40138 group. Amelioration of liver histology was also noted in the NASH + Y-40138 group. Kupffer cell immunohistochemical staining revealed no differences between groups, whereas TNF-α immunohistochemical staining showed fewer stained cells in the NASH + Y-40138 group than in the NASH group. The TNF-α levels in the in-vitro Kupffer cell culture supernatant were lower in the NASH + Y-40138 group than in the NASH group.

CONCLUSION: Administration of Y-40138 to NASH model rats reduced hepatic inflammation and suppressed fibrosis. These results indicate that the multiple cytokine production modulator, Y-40138, is promising as a novel treatment for NASH.

Innate immune reactivity of the liver in rats fed a choline-deficient L-amino-acid-defined diet

AIM: To investigate the innate immune reactivity of tumor necrosis factor-alpha (TNF-α), Toll-like receptor 4 (TLR4), and CD14 in the liver of non-alcoholic steatohepatitis (NASH) model rats.

METHODS: Male F344 rats were fed a choline-deficient L-amino-acid-defined (CDAA) diet. The rats were killed after 4 or 8 wk of the diet, and their livers were removed for immunohistochemical investigation and RNA extraction. The liver specimens were immunostained for TNF-α, TLR4, and CD14. The gene expressions of TNF-α, TLR4, and CD14 were determined by reverse-transcriptase polymerase chain reaction (RT-PCR). Kupffer cells were isolated from the liver by Percoll gradient centrifugation, and were then cultured to measure TNF-α production.

RESULTS: The serum and liver levels of TNF-α in the CDAA-fed rats increased significantly as compared with the control group, as did the immunohistochemical values and gene expressions of TNF-α, TLR4, and CD14 with the progression of steatohepatitis. TNF-α production from the isolated Kupffer cells of the CDAA-fed rats was elevated by lipopolysaccharide stimulation.

CONCLUSION: The expressions of TNF-α, TLR4, and CD14 increased in the NASH model, suggesting that TLR4 and CD14-mediated endotoxin liver damage may also occur in NASH.

Reduction of fibrosis in a rat model of non-alcoholic steatohepatitis cirrhosis by human HGF gene transfection using electroporation

BACKGROUND AND AIM

To study the histological changes caused by transfection of the hepatocyte growth factor (HGF) gene using electroporation (EP) in a non-alcoholic steatohepatitis (NASH) cirrhotic liver model.

METHODS

NASH cirrhotic livers were prepared by administering a choline-deficient diet to 5-week-old male Wister rats for 12 weeks. Three groups of rats were used: rats in the G(+) group were transfected with the GFP gene using EP, rats in the H(+) group were transfected with the HGF gene using EP, and rats in the H(-) group were only injected with the HGF gene. Rats were sacrificed 2 days after gene transfection, and the Azan positive rate (APR) and Sudan positive rate (SPR) were calculated to evaluate fibrosis and fatty changes.

RESULTS

The APR of the NASH cirrhotic livers was significantly higher than that in the normal livers. The APR did not decrease in the G(+) group and the H(-) group, but decreased significantly in the nonelectroporated as well as electroporated areas of the H(+) group. For SPR, there were no significant differences between the G(+), H(-), and H(+) groups.

CONCLUSION

The improvement of fibrosis was not significant when a direct injection of the HGF gene was used alone, but it was enhanced by the concomitant use of EP. However, no efficacy was observed in fat components. These findings suggest that transfection of the HGF gene by EP may lead to an improvement of irreversible cirrhotic livers to reversible fatty livers.

Tissue fibrosis and carcinogenesis: divergent or successive pathways dictate multiple molecular therapeutic targets for oligo decoy therapies

The extracellular matrix (ECM) is composed of several families of macromolecular components: fibrous proteins such as collagens, type I collagen (COL1), type III collagen (COL3), fibronectin, elastin, and glycoconjugates such as proteoglycans and matrix glycoproteins. Their receptors on the cell membrane, most of which in the case of the ECM belong to the integrins, which are heterodimeric proteins composed of alpha and beta chains. COL1 is the major fibrous collagen of bone, tendon, and skin; while COL3 is the more pliable collagen of organs like liver. Focus will not only be given to the regulation of synthesis of several fibrogenic parameters but also modulation of their degradation during growth factor-induced tissue fibrosis and cancer development. Evidence will be provided that certain tissues, which undergo fibrosis, also become cancerous. Why does there exist a divergency between tissues, which undergo frank fibrosis as an endpoint, and those tissues that undergo fibrosis and subsequently are susceptible to carcinogenicity; resulting from the etiological factor(s) causing the initial injury? For example, why does a polyvinyl alcohol (PVA) sponge implant become encapsulated and filled with fibrous tissue then fibrosis tissue growth stops? Why does the subcutaneous injection of a fibrogenic growth factor cause a benign growth and incisional wounding results in fibrosis and ultimately scarring? There are many examples of tissues, which undergo fibrosis as a prerequisite to carcinogenesis. Is there a cause-effect relationship? If you block tissue fibrosis in these precancerous tissues, would you block cancer formation? What are the molecular targets for blocking fibrosis and ultimately carcinogenesis? How can oligo decoys may be used to attenuate carcinogenesis and which oligo decoys specifically attenuate fibrogenesis as a prelude to carcinogenesis? What are other molecular targets for oligo decoy therapy in carcinogenesis?

Herbal medicine Rhei rhizome prevents liver fibrosis in rat liver cirrhosis induced by a choline-deficient L-amino acid-defined diet

The aim of this study was to investigate whether herbal medicine Rhei rhizome, extract powder from herbs, has influences on the development of liver fibrosis. In in vivo studies the effects of Rhei rhizome were examined using the choline-deficient L-amino acid-defined (CDAA) diet-induced liver fibrosis model. In In vitro studies the effects of Rhei rhizome on type I procollagen mRNA expression, alpha-smooth muscle actin (alpha-SMA), metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) of isolated hepatic stellate cell were examined. In vivo Rhei rhizome prevented fibrosis in a dose-dependent manner up to 1.0% (w/w) with a reduced number of activated stellate cells. In vitro the Rhei rhizome prevented stellate cell activation resulting in reduced type I procollagen mRNA, alpha-SMA and TIMP-1, 2 expression. These results indicate that Rhei rhizome significantly reduces liver fibrosis by the direct inhibition of stellate cell activation without reducing hepatocyte cell death.

The flavonoid naringenin inhibits dimethylnitrosamine-induced liver damage in rats

Naringenin, a phytoalexin found in grapefruits and tomatoes, has been reported to exhibit a wide range of pharmacological properties. In this study, we investigated the protective effect of naringenin on hepatic injury induced by dimethylnitrosamine (DMN) in rats. Oral administration of naringenin (20 and 50 mg/kg daily for 4 weeks) remarkably prevented the DMN-induced loss in body and liver weights and inhibited the elevation of serum alanine transaminase, aspartate transaminase, alkaline phosphatase, and bilirubin levels. Naringenin also restored serum albumin and total protein levels, and reduced the hepatic level of malondialdehyde. Furthermore, DMN-induced collagen accumulation, as estimated by histological analysis of liver tissue stained with Sirius red, was reduced in the naringenin-treated rats. A reduction in hepatic stellate cell activation, as assessed by alpha-smooth muscle actin staining, was associated with naringenin treatment. In conclusion, these results demonstrate that naringenin exhibited in vivo hepatoprotective and anti-fibrogenic effects against DMN-induced liver injury. It suggests that naringenin may be useful in preventing the development of hepatic fibrosis.

Pioglitazone prevents hepatic steatosis, fibrosis, and enzyme-altered lesions in rat liver cirrhosis induced by a choline-deficient l-amino acid-defined diet

Non-alcoholic steatohepatitis (NASH) may progress to liver cirrhosis, and NASH patients with liver cirrhosis have a risk of development of hepatocellular carcinoma. Peroxisome proliferator-activated receptor (PPAR) gamma ligand has recently been reported to have improved the condition of patients with NASH. The aim of this study was to investigate whether pioglitazone, a PPARgamma ligand, has any influence on the animal model of NASH as well as isolated hepatic stellate cells. In vivo, the effects of pioglitazone were examined using the choline-deficient L-amino acid-defined (CDAA)-diet liver fibrosis model. After two weeks, pioglitazone improved hepatic steatosis, prevented liver fibrosis, and reduced preneoplastic lesions in the liver after 10 weeks. Pioglitazone reduced the expression of TIMP-1 and TIMP-2 mRNA without changing MMP-13 mRNA expression compared to the liver fed a CDAA diet alone. In vitro, pioglitazone prevented the activation of hepatic stellate cells resulting in reducing the expression of type I procollagen, MMP-2, TIMP-1, and TIMP-2 mRNA with increased MMP-13 mRNA expression. These results indicate that pioglitazone may be one of the candidates for the benefit drugs for the liver disease of patients with NASH.

Herbal medicine Inchin-ko-to (TJ-135) prevents liver fibrosis and enzyme-altered lesions in rat liver cirrhosis induced by a choline-deficient L-amino acid-defined diet

BACKGROUND/AIMS

The herbal medicine Inchin-ko-to (TJ-135), extract power from three herbs, has recently been reported possessing anti-apoptotic activity. The aim of this study was to investigate whether TJ-135 has any influence on the development of preneoplastic lesions as well as liver fibrosis.

METHODS

The effects of the TJ-135 were examined using the choline-deficient L-amino acid-defined diet-induced liver fibrosis model. In addition, the effect of TJ-135 on mitogen-activated protein (MAP) kinase, type III procollagen mRNA expression and the medium N-terminal procollagen III propeptide (PIIINP) concentration in a hepatic stellate cell line (LI90) were examined.

RESULTS

TJ-135 prevented fibrosis in a dose-dependent manner up to 1.5% (w/w). TJ-135 also reduced the expression of type III procollagen mRNA in the liver, as well as the number of activated stellate cells. Furthermore, TJ-135 reduced the area of preneoplastic lesions in the liver. With LI90 cells, TJ-135 reduced MAP kinase (ERK and JNK but not P38) activities resulting in reduced type III procollagen mRNA and PIIINP concentrations in the medium in a dose-dependent manner.

CONCLUSIONS

These results indicate that although TJ-135 has anti-apoptotic activity, TJ-135 does not increase preneoplastic lesions but significantly reduces liver fibrosis through the inhibition of stellate cell activation without a reduction of hepatocyte cell death.

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

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

Tyrosinemia I, a model for human diseases mediated by 2-oxoacid-utilizing dioxygenases: hepatotoxin suppression by NTBC does not normalize hepatic collagen metabolism

OBJECTIVES

Medical treatment of tyrosinemia I relies on the herbicide NTBC [Orfadin 2-(2-nitro-4-trifluoromethylbenzoyl)-cyclohexane-1,3-dione], an inhibitor of plant and mammalian 2-oxoacid-utilizing dioxygenases with a collective catalytic cycle ('HAG' mechanism). We hypothesize that NTBC-treated tyrosinemia I is a human model for the pathogenic role of two major enzymes in this class, 4-hydroxyphenylpyruvate dioxygenase (4-HPPD; EC 1.13.11.27) and prolyl 4-hydroxylase (P4-H; E.C. 1.14.11.2), essential for tyrosine and collagen metabolism, respectively.

METHODS

In a patient with established tyrosinemia I, we monitored the in vivo activities of 4-HPPD and P4-H via five biomarkers before and during NTBC medication. Hypothesis testing at the molecular level was performed by computational modeling of NTBC binding to the crystal structure-derived active site of 4-HPPD, and then relating these findings to our experimental results and to known P4-H data.

RESULTS

NTBC rapidly normalized the biomarkers for 4-HPPD activity. However, those for P4-H activity remained uniformly elevated after one hundred days on NTBC, the PIIINP biomarker even increasing above its grossly abnormal, initial level. This selective enzyme inhibition despite a collective catalytic cycle is attributed to the conformation of NTBC, which only fits the active site of 4-HPPD, as confirmed by its crystal structure.

CONCLUSIONS

Normalization of hepatic collagen formation, highly desirable in all fibrotic liver diseases, is not achieved by NTBC in tyrosinemia I. By establishing the molecular cause for this failure, our results also establish a rational approach to identify inhibitors that achieve that goal, either by joint 4-HPPD / P-4H inhibition, or by inhibition of only P-4H.

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

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

Quantitative analysis of liver fibrosis and stellate cell changes in patients with chronic hepatitis C after interferon therapy

OBJECTIVE

The proliferation and differentiation of stellate (Ito, or fat-storing) cells into myofibroblast-like cells is responsible for the development of liver fibrosis. Using computer image analysis, we evaluated the changes of alpha smooth muscle actin-positive stellate cells and liver fibrosis after interferon-alpha or -beta (IFN-alpha, beta) therapy in patients with chronic hepatitis C.

METHODS

Patients with chronic hepatitis C were treated with IFN-alpha or -beta and were divided into three groups on the basis of clinical criteria; a complete responder group (CR, 18 of 51), a partial responder group (PR, 17 to 51), and a nonresponder group (NR, 16 of 51). Liver fibrosis was assessed from specimens stained with Sirius red and was quantitated by computer image analysis. We also evaluated alpha-smooth muscle actin expression in the liver before and after IFN therapy by a semiquantitative scoring method (the alpha-smooth muscle actin index).

RESULTS

Before IFN therapy, a large number of stellate cells expressing a-smooth muscle actin were present in the liver biopsy specimens. There was a significant correlation (r = 0.699, p < 0.05) between the change in the percent area of fibrosis and the alpha-smooth muscle actin index before and after IFN therapy in all groups. The complete responder group also showed a significant reduction of a-smooth muscle actin-expressing cells that was correlated with the reduction of serum ALT (r = 0.686, p < 0.05).

CONCLUSION

These results suggest a-smooth muscle actin-expressing cells are responsible for liver fibrosis, and the elimination of factors stimulating matrix synthesis (e.g., hepatitis virus) may decrease liver fibrosis.

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

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

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

BACKGROUND/AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Beta-carotene reduces the ductular (oval) cell reaction in the liver of Wistar rats submitted to the resistant hepatocyte model of carcinogenesis

The morphology of livers of Wistar rats treated with beta-carotene (BC), vitamin A (VA, retinol acetate) or corn oil (CO, controls) and submitted to the resistant hepatocyte model of carcinogenesis was studied. Preneoplastic lesions (PNL) were smaller and less numerous in the BC group. The latter group also presented fewer placental glutathione-S-transferase (GST-P) positive and hematoxylin and eosin (H&E) distinguishable PNL, with smaller mean areas and smaller mean areas of the liver occupied by PNL. Clear cell foci predominated in BC livers. In picrosirius-stained liver sections, fibrosis, whether or not accompanying the bile ductular cells, surrounded only 16.67% of PNL in the BC group, as compared to 35.71% in the VA group and 87.72% in the CO group. Moreover, the ductular cell reaction was smaller in the BC group. Smooth muscle actin-positive cells surrounded some PNL, mostly in CO rats, and less frequently in the VA and BC groups. Examination by transmission electron microscopy (TEM) showed that cells with nuclei similar to those of perisinusoidal cells, devoid of cytoplasmic fat globules, probably represented myofibroblasts derived from Ito cells and accompanied the ductular cell reaction. On the basis of these results, we suggest that BC reduced not only the PNL but also the ductular (oval) cell reaction in this experimental model.

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

BACKGROUND/AIM

The aim of this study was to investigate the effect of interferon gamma on the synthesis of matrix proteins such as collagens with the relation to transforming growth factor-beta1 expression in vivo.

METHODS

We investigated the effects of interferon gamma in a model of liver fibrosis induced by pig serum in male Wistar rats, which develops fibrosis without an increase in serum alanine aminotransferase (i.e., without hepatocyte injury). Rats were injected with 0.5 ml of pig serum twice a week for 8 weeks with or without 20,000 or 50,000 U of interferon gamma.

RESULTS

Interferon gamma at doses up to 50,000 U/day prevented fibrosis, as indicated by reduced hydroxyproline content in the liver. Interferon gamma at 50,000 U/day also reduced expression of type I and III procollagen in the liver. However, the expression of transforming growth factor-beta1 mRNA and protein in the liver was not reduced by interferon gamma. Histologically, interferon gamma at 50,000 U/day also reduced the number of myofibroblast-like cells (activated stellate cells).

CONCLUSIONS

These results indicate that interferon gamma can prevent fibrosis by inhibiting the activation and proliferation of stellate cells, resulting in reduced expression of procollagen without affecting transforming growth factor-beta1 expression in pig serum-induced rat liver fibrosis in vivo.

Herbal medicine Sho-saiko-to (TJ-9) prevents liver fibrosis and enzyme-altered lesions in rat liver cirrhosis induced by a choline-deficient L-amino acid-defined diet

BACKGROUND/AIM

A herbal medicine, Sho-saiko-to (TJ-9), has recently been orally administered to patients with chronic liver disease in Japan and has been reported to inhibit the development of hepatocellular carcinoma. The aim of this study was to investigate whether TJ-9 has an inhibitory effect on the development of preneoplastic lesions and liver fibrosis in rats.

METHODS

The effects of the TJ-9 were examined using the choline-deficient L-amino acid-defined (CDAA) diet-induced liver fibrosis model in 16-week-old male Wistar rats.

RESULTS

TJ-9 (1% w/w) prevented fibrosis, as indicated by reduced hydroxyproline content in the liver and inhibition of the increase in a serum marker of fibrosis (hyaluronic acid), without reducing the increase in serum alanine aminotransferase and aspartate aminotransferase. TJ-9 also reduced the expression of type III procollagen alpha 1 mRNA in the liver, as well as the proliferation of myofibroblast-like cells (activated stellate cells, activated Ito cells). Furthermore, TJ-9 reduced the number of preneoplastic lesions, detected as enzyme-altered (glutathione S-transferase placental form-positive) lesions, in the liver.

CONCLUSIONS

These results indicate that the herbal medicine Sho-saiko-to (TJ-9) prevents fibrosis as well as preneoplastic lesions, not by inhibiting hepatocyte cell death but by inhibiting the activation of stellate cells, which are considered to be the main collagen-producing cells, leading to a reduction in the development of preneoplastic lesions.

Prolyl 4-hydroxylase inhibitor (HOE 077) inhibits pig serum-induced rat liver fibrosis by preventing stellate cell activation

BACKGROUND/AIMS

The aim of this study was to investigate the effect and mechanism of fibrosuppression by a newly synthesized prolyl 4-hydroxylase inhibitor [HOE 077, 2, 4-pyridine dicarboxylic acid bis [(2-methoxyethyl) amide]] on pig serum-induced liver fibrosis in the rat.

METHODS

Male Wistar rats received 0.5 ml of pig serum twice a week for 10 weeks with 0, 100 or 200 ppm of HOE 077. At the end of the experiment, the hydroxyproline content of the liver, and alanine aminotransferase were measured. Histological stains used were HE, azan and a stain for alpha-smooth muscle actin (alpha-SMA). Electron microscopy was also performed. Messenger RNA expressions of type I and III procollagen were examined by Northern blot analysis. alpha-SMA positive cells and fibers with azan staining were assessed as percent area of the tissue specimen, using an image analysis system.

RESULTS

Rats that received pig serum for 10 weeks showed an increased liver hydroxyproline content of 318+/-39 microg/g wet weight (n=15). HOE 077 at doses up to 200 ppm significantly (p<0.01) reduced this increase of liver hydroxyproline content (181+/-39 microg/g wet weight, n=15) in accordance with improved histological findings. 200 ppm of HOE 077 significantly reduced mRNA expressions of alpha2(I) (486+/-102 vs 151+/-36, p<0.01) and alpha1(III) (276+/-127 vs 160+/-67, p<0.05) procollagen and percent area of alpha-SMA positive cells (2.94+/-2.14 vs 1.17+/-0.88%). Electron microscopy revealed that 200 ppm of HOE 077 prevented the loss of fat droplets.

CONCLUSIONS

A prolyl 4-hydroxylase inhibitor (HOE 077) prevented pig serum-induced rat liver fibrosis by inhibiting stellate cell activation.