[Effects and comparison of seed oil and sarcocarp oil of Hippophae rhamnoides on rats with experimental hepatocirrhosis]

OBJECTIVE

A study was carried out to investigate the effects of seed oil and sarcocarp oil of Hippophae rhamnoides on rats with experimental hepatocirrhosis, and comparison between the two.

METHOD

A rat model of experimental hepatocirrhosis was set up by feeding CCl4. Different concentration of seed oil and sarcocarp oil of H. rhamnoides were feed to those rats for 45 d, then the changes of activity of ALT in serum and SOD in liver were measured.

RESULT

Both of seed oil and sarcocarp oil can control the increase of ALT in serum and the decrease of SOD evidently, and the effect of seed oil was turn out to be a little better than sarcocarp oil.

CONCLUSION

Seed oil was more effective than sarcocarp oil of H. rhamnoides in alleviating liver injury caused by CCl4.

[Effect of Hovenia dulcis extract on expression of MMP-13 and TIMP-1 in hepatic tissue]

OBJECTIVE

To investigate the effects of Hovenia dulcis extract on mRNA expression of MMP-13 and TIMP-1 mRNA in hepatic tissue in experimental rats.

METHOD

48 male Sprague-Dawley rats were randomly divided into 2 groups: normal group (16) and model group (32), hepatic fibrosis was induced by CCl4 for 6 weeks in rats, 8 rats were sacrificed at the end of the 6th week from every group respectively, HE staining of hepatic tissue was performed; In the model group, rats randomly subdivided into 3 groups: spontaneous recovery group, control group and medication administration group, 8 rats were sacrificed at the end of the 12th week from every group respectively, the mRNA levels of MMP-13 and TIMP-1 in hepatic tissue were assayed by semi-quantitative RT-PCR.

RESULT

The mRNA expression of MMP-13 among the 4 groups were not statistically significant, but the mRNA expression of TIMP-1 among the 4 groups were statiscally significant. The levels of TIMP-1 mRNA were significantly increased in control group and medication administration group compared, with those in the model group (P < 0.05), and reverse effects of medication administration groups were significantly high than those of control group (P < 0.05).

CONCLUSION

Inhibition of the mRNA expression of TIMP-1 may be the mechanism of reversing hepatic fibrosis H. dulcis, for thus collogen degradation system was recoveried gradually.

Oxidative stress in the development of liver cirrhosis: a comparison of two different experimental models

BACKGROUND/AIMS

Oxidative stress has been implicated in liver cirrhosis. Carbon tetrachloride and thioacetamide are the most widely used models to develop cirrhosis in rats and the present study compares oxidative stress in the liver induced by these compounds at different stages of cirrhosis development.

METHODS

Twice-weekly intragastric or intraperitoneal administration of carbon tetrachloride or thioacetamide, respectively, produced liver cirrhosis after 3 months. Histology, serum markers and hepatic hydroxy proline content confirmed the cirrhosis.

RESULTS

An increase in oxidative stress parameters was seen in mitochondria, peroxisomes and microsomes from the liver after carbon tetrachloride or thioacetamide treatment. Oxidative stress was more severe in carbon tetrachloride treated animals than thioacetamide. Mild oxidative stress was evident at 1 and 2 months of treatment and a significant increase was seen by 3 months of treatment with either compound. By this time, frank liver cirrhosis was also observed.

CONCLUSIONS

These results suggest that evidence of oxygen free radicals is also found early in the development of fibrosis and cirrhosis in both models.

Inhibition of hepatic fibrogenesis by matrix metalloproteinase‐9 mutants in mice

Tissue inhibitor of metalloproteinases-1 (TIMP-1) plays a crucial role in the pathogenesis of hepatic fibrosis and thus may represent an important therapeutic target in the design of anti-fibrotic strategies for chronic liver disease. We present an innovative therapy based on the assignment of inactivated enzymes acting as scavengers for TIMP-1. Hepatic fibrosis was induced in BALB/c mice by repetitive intraperitoneal CCl4 injection. The animals were treated with proteolytic inactive matrix metalloproteinase-9 mutants (E402Q, H401A, E402H/H411E) using adenovirus-mediated gene transfer. Application of these MMP-9 mutants inhibited fibrogenesis, which was indicated by decreasing portal and periportal accumulation of collagen. Total hydroxyproline of liver tissue, the morphometric stage of fibrosis as well as mRNA expression of marker proteins for hepatic fibrosis in livers of E402Q- and H401A-treated mice were significantly reduced. MMP-9 mutants suppressed transdifferentiation of hepatic stellate cells to the myofibroblast like phenotype in vitro and in vivo. Moreover, adenoviral application of the mutants MMP-9-H401A and -E402Q led to increased apoptosis of activated hepatic stellate cells, thought to be the main promoters of hepatic fibrosis. Application of MMP-9 mutants as TIMP-1 scavengers may provide a new therapeutic strategy for hepatic fibrosis.

Tumour necrosis factor alpha signalling through activation of Kupffer cells plays an essential role in liver fibrosis of non-alcoholic steatohepatitis in mice

BACKGROUND

While tumour necrosis factor alpha (TNF-alpha) appears to be associated with the development of non-alcoholic steatohepatitis (NASH), its precise role in the pathogenesis of NASH is not well understood.

METHODS

Male mice deficient in both TNF receptors 1 (TNFR1) and 2 (TNFR2) (TNFRDKO mice) and wild-type mice were fed a methionine and choline deficient (MCD) diet or a control diet for eight weeks, maintaining isoenergetic intake.

RESULTS

MCD dietary feeding of TNFRDKO mice for eight weeks resulted in attenuated liver steatosis and fibrosis compared with control wild-type mice. In the liver, the number of activated hepatic Kupffer cells recruited was significantly decreased in TNFRDKO mice after MCD dietary feeding. In addition, hepatic induction of TNF-alpha, vascular cell adhesion molecule 1, and intracellular adhesion molecule 1 was significantly suppressed in TNFRDKO mice. While in control animals MCD dietary feeding dramatically increased mRNA expression of tissue inhibitor of metalloproteinase 1 (TIMP-1) in both whole liver and hepatic stellate cells, concomitant with enhanced activation of hepatic stellate cells, both factors were significantly lower in TNFRDKO mice. In primary cultures, TNF-alpha administration enhanced TIMP-1 mRNA expression in activated hepatic stellate cells and suppressed apoptotic induction in activated hepatic stellate cells. Inhibition of TNF induced TIMP-1 upregulation by TIMP-1 specific siRNA reversed the apoptotic suppression seen in hepatic stellate cells.

CONCLUSIONS

Enhancement of the TNF-alpha/TNFR mediated signalling pathway via activation of Kupffer cells in an autocrine or paracrine manner may be critically involved in the pathogenesis of liver fibrosis in this NASH animal model.

Dynamic observation of liver fibrosis in mice infected with Schistosoma japonica

The expression of TNF-alpha in the liver at different periods post Schistosoma japonica infection and the effect on liver fibrosis after supplementary injection of these cytokines were investigated. The mice infected with schistosome cercariae were divided into 3 groups: normal control group, TNF-alpha-untreated infection group and TNF-alpha-treated infection group. ABC immunohistochemistry and pathologic image multimedia quantification system were applied to dynamically detect the activity of TNF-alpha. The results showed that the levels of TNF-alpha in the liver in TNF-alpha-untreated infection group were slowly decreased with prolongation of infection time (from 8th, 11th, 14th to 18th week), while in the TNF-alpha-treated infection group, those were increased significantly after intraperitoneal injection of TNF-alpha at 6th week after infection. At first to 8th week after the final injection of TNF-alpha, the intrahepatic TNF-alpha levels in the TNF-alpha-treated infection group were significantly higher than in the other two groups (P < 0.01), and the granulomatous inflammation and fibrosis in the liver were also milder in the normal control group. It was concluded that at the early stage of Schistosoma japonica infection mouse liver mainly released Th1 cytokine and TNF-alpha from Th1 activated macrophages. Six weeks after infection (post egg deposition), exogenous supplement with intraperitoneal injection of TNF-alpha could induce the enhanced expression of Th1 cytokines and alleviate the liver granulomatous inflammation and fibrosis.

Chronic liver disease is triggered by taurine transporter knockout in the mouse

Taurine is an abundant organic osmolyte with antioxidant and immunomodulatory properties. Its role in the pathogenesis of chronic liver disease is unknown. The liver phenotype was studied in taurine transporter knockout (taut-/-) mice. Hepatic taurine levels were ~21, 15 and 6 mumol/g liver wet weight in adult wild-type, heterozygous (taut+/-) and homozygous (taut-/-) mice, respectively. Immunoelectronmicroscopy revealed an almost complete depletion of taurine in Kupffer and sinusoidal endothelial cells, but not in parenchymal cells of (taut-/-) mice. Compared with wild-type mice, (taut-/-) and (taut+/-) mice developed moderate unspecific hepatitis and liver fibrosis with increased frequency of neoplastic lesions beyond 1 year of age. Liver disease in (taut-/-) mice was characterized by hepatocyte apoptosis, activation of the CD95 system, elevated plasma TNF-alpha levels, hepatic stellate cell and oval cell proliferation, and severe mitochondrial abnormalities in liver parenchymal cells. Mitochondrial dysfunction was suggested by a significantly lower respiratory control ratio in isolated mitochondria from (taut-/-) mice. Taut knockout had no effect on taurine-conjugated bile acids in bile; however, the relative amount of cholate-conjugates acid was decreased at the expense of 7-keto-cholate-conjugates. In conclusion, taurine deficiency due to defective taurine transport triggers chronic liver disease, which may involve mitochondrial dysfunction.

Serological and immunohistochemical studies on porcine-serum-induced hepatic fibrosis in rats

We previously reported that the strain difference in the development of porcine-serum (PS)-induced rat hepatic fibrosis was closely related to the difference in the mode of MHC class-II-related genes expression. This study was carried out to clarify the serological and immunohistochemical changes in this hepatic fibrosis model. Six-week-old male Brown Norway (BN) and Wistar rats were injected with 0.5 ml of sterile PS twice a week for up to 8 weeks. The serum levels of PS-specific IgG1, IgG2a, and IgM were elevated more prominently in BN rats than Wistar rats. In the liver, significant increases in the numbers of PS-, OX-6 (RT1.B)-, CD4-, CD8, ED1-, and ED2-positive cells occurred earlier in BN rats than Wistar rats. At 8 weeks, deposition of PS and immunoglobulins was observed in hepatic fibrous septa and renal glomerular mesangium, and IgG1- and IgG2a-positive cells were found in the white pulp of the spleen. The present results suggest that humoral immunity probably regulated by MHC class II molecules and inflammatory cells may be involved in PS-induced hepatic fibrosis in rats.

Expression of cytokeratins 8 and 18 on Mallory body and oval cell in rats during hepatic fibrosis

BACKGROUND

The aim of this study was to determine the induction and distribution of Mallory body (MB) and oval cells in carbon-tetrachloride (CCl4)-induced rat liver fibrosis.

MATERIALS AND METHODS

MBs and oval cells expressing cytokeratins (CKs) 8 and 18 were monitored by immuno-histochemistry and immunoblotting.

RESULTS

MBs were mainly detected within hepatocytes near the fibrotic areas, and oval cells were located along or in the fibrotic areas. Both MBs and oval cells increased in size and number in the development of fibrosis. At cirrhotic liver, most of the oval cells were located in the fibrous septa and around newly formed bile ductules. Moreover, as hepatic injuries developed into fibrosis, a much more prominent single band of CK18 was detected.

CONCLUSION

The occurrence and distribution of MB and oval cells in CCl4-induced rat liver fibrosis are reported. This represents the first CCl4 experimental in vivo model of MB induction, which will be useful for further investigations on the pathogenesis of MB.

Cross-talk between farnesoid-X-receptor (FXR) and peroxisome proliferator-activated receptor gamma contributes to the antifibrotic activity of FXR ligands in rodent models of liver cirrhosis

The nuclear receptors farnesoid X receptor (FXR) and peroxisome proliferator-activated receptor (PPAR)gamma exert counter-regulatory effects on hepatic stellate cells (HSCs) and protect against liver fibrosis development in rodents. Here, we investigated whether FXR ligands regulate PPARgamma expression in HSCs and models of liver fibrosis induced in rats by porcine serum and carbon tetrachloride administration and bile duct ligation. Our results demonstrate that HSCs trans-differentiation associated with suppression of PPARgamma mRNA expression, whereas FXR mRNA was unchanged. Exposure of cells to natural and synthetic ligands of FXR, including 6-ethyl chenodeoxycholic acid (6-ECDCA), a synthetic derivative of chenodeoxycholic acid, reversed this effect and increased PPARgamma mRNA by approximately 40-fold. Submaximally effective concentrations of FXR and PPARgamma ligands were additive in inhibiting alpha1(I) collagen mRNA accumulation induced by transforming growth factor (TGF)beta1. Administration of 6-ECDCA in rats rendered cirrhotic by porcine serum and carbon tetrachloride administration or bile duct ligation reverted down-regulation of PPARgamma mRNA expression in HSCs. Cotreatment with 6-ECDCA potentiates the antifibrotic activity of rosiglitazone, a PPARgamma ligand, in the porcine serum model as measured by morphometric analysis of liver collagen content, hydroxyproline, and liver expression of alpha1(I) collagen mRNA, alpha-smooth muscle actin, fibronectin, TGFbeta1, and tissue inhibitor of metalloprotease 1 and 2, whereas it enhanced the expression of PPARgamma and uncoupling protein 2, a PPARgamma-regulated gene, by 2-fold. In conclusion, by using an in vitro and in vivo approach, we demonstrated that FXR ligands up-regulate PPARgamma mRNA in HSCs and in rodent models of liver fibrosis. A FXR-PPARgamma cascade exerts counter-regulatory effects in HSCs activation.

TNF-alpha and leptin in experimental liver fibrosis models induced by carbon tetrachloride and by common bile duct ligation

In this study we investigated TNF-alpha and leptin levels in two different liver fibrosis models induced by carbon tetrachloride (CCl(4)) and common bile duct ligation (CBDL). A total of 36 male rats of Albino-Wistar strain were allocated to three groups. One of the groups was the control. The second group received 0.15 ml 100 g(-1) CCl(4) subcutaneously for 6 weeks, 3 days per week. The third group underwent common bile duct ligation (CBDL) and was monitored for 4 weeks. Histopathological investigation included fibrosis, steatosis and inflammation. Serum IL-6 and TNF-alpha levels were analysed by ELISA methods and leptin was analysed by RIA. Fibrosis and steatosis increased significantly in the CCl(4) group in comparison with the CBDL group (p < 0.01; p < 0.001). Leptin and TNF-alpha levels in CCl(4) group were higher than those in the CBDL and control groups (p < 0.05). TNF-alpha and leptin levels were not related to each another in either the CCl(4) group or the CBDL group (r=0.22, p > 0.05; r=0.19, p > 0.05). The IL-6 level was higher in the CCl(4) group in relation to severity of inflammation (p < 0.05). TNF-alpha and leptin levels were higher in animals with liver fibrosis induced by CCl(4), than they were in those whose liver fibrosis was induced by common bile duct ligation. Leptin and TNF-alpha may be less effective on the development of liver fibrosis in the group which underwent common bile duct ligation.

The plasticity of p19 ARF null hepatic stellate cells and the dynamics of activation

In the healthy adult liver, quiescent hepatic stellate cells (HSCs) present the major site for vitamin A storage in cytoplasmic lipid droplets. During liver injury due to viral infection or alcohol intoxication, HSCs get activated and produce high amounts of extracellular matrix components for tissue repair and fibrogenesis. Employing p19 ARF deficiency, we established a non-transformed murine HSC model to investigate their plasticity and the dynamics of HSC activation. Primary HSCs isolated from livers of adult p19 ARF null mice underwent spontaneous activation through long-term passaging without an obvious replicative limit. The immortalized cell line, referred to as M1-4HSC, showed stellate cell characteristics including the expression of desmin, glial fibrillary acidic protein, alpha-smooth muscle actin and pro-collagen I. Treatment of these non-tumorigenic M1-4HSC with pro-fibrogenic TGF-beta1 provoked a morphological transition to a myofibroblastoid cell type which was accompanied by enhanced cellular turnover and impaired migration. In addition, M1-4HSCs expressed constituents of cell adhesion complexes such as p120(ctn) and beta-catenin at cell borders, which dislocalized in the cytoplasm during stimulation to myofibroblasts, pointing to the epitheloid characteristics of HSCs. By virtue of its non-transformed phenotype and unlimited availability of cells, the p19(ARF) deficient model of activated HSCs and corresponding myofibroblasts render this system a highly valuable tool for studying the cellular and molecular basis of hepatic fibrogenesis.

[Dynamic expression of matrix metalloproteinase-2, membrane type-matrix metalloproteinase-2 in experimental hepatic fibrosis and its reversal in rat]

OBJECTIVE

To investigate the expression dynamics and significance of matrix metalloproteinase-2 (MMP-2) membrane type-matrix metalloproteinase-2 (MT-MMP-2) in hepatic fibrosis and its reversal counterpart.

METHODS

An experimental CCl4 induced hepatic fibrosis rat model was established by intraperitoneal administration of carbon tetrachloride for 2, 4, 6, 8, 10 weeks, and normal rats were used as a control group. The immunohistochemical methods and in situ hybridization were used to detect MMP-2,MT-MMP-2 mRNA and related antigens in the liver.

RESULTS

MMP-2,MT-MMP-2 mRNA and related antigens were expressed in mesenchymal cells and parts of hepatocytes besides active pathological changes, especially in the fibrous septum and portal area. Expression of MMP-2,MT-MMP-2 mRNA and related antigens were increased in hepatic fibrosis and decreased gradually in its reversal counterpart.

CONCLUSION

This study suggested that mesenchymal cells are the main cellular origins of MMPs. The levels of MMP-2 and MT-MMP-2 antigens and gene expression were closely related to hepatic fibrosis. MMP-2 and MT-MMP-2 may play important roles in hepatic fibrosis and its reversal counterpart.

A dual reporter gene transgenic mouse demonstrates heterogeneity in hepatic fibrogenic cell populations

Activation of hepatic stellate cells (HSCs) and other resident mesenchymal cells into myofibroblasts expressing alpha smooth muscle actin (alphaSMA) and collagen I is a key event in liver fibrogenesis. However, the temporal expression profiles of alphaSMA and collagen I genes in these cells is unknown. To address this question, we studied alphaSMA and collagen alpha1(I) transcriptional patterns in primary cultures of HSCs, and additionally, in an in vivo model of secondary biliary fibrosis using transgenic mice that express the Discomsoma sp. red fluorescent protein (RFP) and the enhanced green fluorescent protein (EGFP) reporter genes under direction of the mouse alphaSMA and collagen alpha1(I) promoter/enhancers, respectively. The alphaSMA-RFP mice were crossed with collagen-EGFP mice to generate double transgenic mice. Reporter gene expression in cultured HSCs demonstrated that both transgenes were induced at day 3 with continued expression through day 14. Interestingly, alphaSMA and collagen alpha1(I) transgenes were not coexpressed in all cells. Flow cytometry analysis showed three different patterns of gene expression: alphaSMA-RFP positive cells, collagen-EGFP positive cells, and cells expressing both transgenes. AlphaSMA-only and alphaSMA/collagen expressing cells showed higher expression levels of synaptophysin, reelin, MMP13, TIMP1, and ICAM-1 compared to collagen-only expressing cells, as assessed by real-time PCR. Following bile duct ligation, alphaSMA and collagen alpha1(I) transgenes were differentially expressed by peribiliary, parenchymal and vascular fibrogenic cells. Peribiliary cells preferentially expressed collagen alpha1(I), while parenchymal myofibroblasts expressed both alphaSMA and collagen alpha1(I). In conclusion, these data demonstrate heterogeneity of gene expression in myofibroblastic cells during active fibrogenesis. These reporter mice provide a useful tool to further characterize fibrogenic cell types and to evaluate antifibrotic drugs.

Japanese herbal medicine Inchin-ko-to as a therapeutic drug for liver fibrosis

BACKGROUND/AIMS

Inchin-ko-to (TJ-135) is an herbal medicine used in Japan for treatment of icteric patients with cirrhosis. Its efficacy as an anti-fibrogenic drug was evaluated in relation to stellate cell activation.

METHODS/RESULTS

Liver fibrosis was induced in rats by repeated injections of carbon tetrachloride (CCl4) or pig-serum. Oral administration of TJ-135 improved the mortality of rats given CCl4 with reduced extents of liver necrosis and fibrosis. Similar improvement of liver fibrosis was found in rats given pig-serum showing no liver necrosis. DNA synthesis of stellate cells activated in vitro after isolation from normal rat liver was decreased by culture with TJ-135 in a dose-related manner, accompanied by decreased smooth muscle alpha actin expression and contractility. Such attenuation was not found in the cells cultured with geniposide, an iridoid compound of TJ-135, but genipin, an aglycone of geniposide formed in the gut by action of bacterial flora, markedly decreased stellate cell activation without affecting synthesis of proteins other than collagen.

CONCLUSIONS

TJ-135 may be useful for treatment of liver fibrosis and portal hypertension through suppression of activated hepatic stellate cell function by genipin, an absorbed form of its component.

Inhibitory effect of leflunomide on hepatic fibrosis induced by CCl4 in rats

AIM

To study the effect of leflunomide on CCl4-induced hepatic fibrosis in rats.

METHODS

Hepatic fibrosis was induced by subcutaneous injection with 50% CCl4 in Sprague-Dawley rats. The amount of CCl4 administered was 1 mg/kg. The alanine aminotransferase (ALT), aspartate aminotransferase (AST), nitric oxide (NO) levels in plasma and hydroxyproline (Hyp) contents in liver tissue were assayed by spectrophotometry. The hyaluronic acid (HA) and procollagen III (PC III) were assessed by radioimmunoassay. The transforming growth factor-beta1 (TGF-beta1) in serum was determined by ELISA. The nuclear factor-kappa B (NF-kappaB) in liver tissue was examined by immunohistochemistry. Liver samples collected after 12 weeks of CCl4 treatment were stained with hematoxylin and eosin.

RESULTS

Leflunomide (1, 3, and 9 mg/kg) significantly decreased indices of liver and spleen, the serum transaminase (AST, ALT) activities, HA and PC III levels, and Hyp contents in liver tissue in rats of hepatic fibrosis. Histopathological examination showed leflunomide had inhibitory effect on fibrogenesis and formation of pseudolobulus. Furthermore, leflunomide significantly inhibited NF-kappaB expression in liver tissue, and reduced elevated serum TGF-kappa1 and NO levels in rats of hepatic fibrosis.

CONCLUSION

Leflunomide showed inhibitory action on hepatic fibrosis induced by CCl4 in rats.

Anti-fibrogenic effects of captopril and candesartan cilexetil on the hepatic fibrosis development in rat. The effect of AT1-R blocker on the hepatic fibrosis

BACKGROUND/AIM

Angiotensin converting enzyme (ACE) and angiotensin II (AT-II) have been suggested to play an important role in liver fibrogenesis. There is a significant relationship between inheritance of hightened expression of transforming growth factor beta1 (TGF-beta1) and AT-II and the development of progressive hepatic fibrosis. The purpose of this study was to investigate the effects of captopril, an ACE inhibitor and candesartan cilexetil, an AT-II type 1 receptor (AT1-R) blocker, on liver fibrosis induced in rats by carbon tetrachloride (CCl4) administration.

METHODS

rats were divided into 4 experimental groups: The first group was given CCl4 alone; the second was given both CCl4 and captopril (100 mg x kg(-1) x day(-1)); the third was given both CCl4 and candesartan cilexetil (8 mg x kg(-1) x day(-1)); fourth group was given 0.9% NaCl only. Seven weeks after initiating the treatment, indices of fibrosis were assessed.

RESULTS

Candesartan cilexetil treatment significantly reduced the fibrosis development. These inhibitory effects were not observed in the captopril-treated group. The mean fibrosis score was significantly lower in the CCl4/candesartan group compared with the group applied to CCl4 alone and the group applied to CCl4/captopril. Similarly, the number of alpha-smooth muscle actin positive cells was markedly suppressed by candesartan treatment.

CONCLUSIONS

The results suggest that AT-II plays a pivotal role in hepatic fibrogenesis and candesartan significantly attenuates the progression of liver fibrosis. This drug may provide an effective new strategy for prevention of liver fibrosis. Its effectiveness should be investigated in chronic liver disease associated with progressive fibrosis.

[Studies on Smads at transcription level in liver fibrosis of mice with Schistosomiasis japonica]

OBJECTIVE

To study Smads involved in TGF-beta signal transduction at the transcription level during the development of liver fibrosis in BALB/c mice infected by Schistosoma japonicum.

METHODS

BALB/c mice infected with cercariae of S. japonicum were used as liver fibrosis models. Liver specimens were harvested at 8, 12, 16 and 24 weeks after infection and normal control were sacrificed at the 24th week. A part of the liver specimens were preserved for pathologic examination and the other part was frozen for the detection of mRNA level of Smad 2, Smad 3, Smad 4 and Smad 7.

RESULTS

The level of Smad 3 mRNA was significantly higher than that of control at the later stage, while the mRNA level of Smad 2 decreased at 12 and at 24 weeks, respectively. No significant difference in the mRNA level of Smad 4 and Smad 7 was observed between the infection group and the control.

CONCLUSION

Smad 3 may induce the development of liver fibrosis in mice infected by S. japonicum while Smad 2 may induce the development of liver fibrosis at early stage and inhibit it at later stage.

Sequential changes in redox status and nitric oxide synthases expression in the liver after bile duct ligation

Bile duct ligation (BDL) in rats induces portal fibrosis. This process has been linked to changes in the oxidative state of the hepatic cells and in the production of nitric oxide. Our objective was to find possible temporal connections between hepatic redox state, NO synthesis and liver injury. In this work we have characterized hepatic lesions 17 and 31 days after BDL and determined changes in hepatic function, oxidative state, and NO production. We have also analyzed the expression and localization of inducible NO synthase (NOS2) and constitutive NO synthase (NOS3). After 17 and 31 days from ligature, lipid peroxidation is increased and both plasma concentration and biliary excretion of nitrite+nitrate are rised. 17 days after BDL both NOS2 and NOS3 are expressed intensely and in the same regions. 31 days after BDL, the expression of NOS2 remains elevated and is localized mostly in preserved hepatocytes in portal areas and in neighborhoods of centrolobulillar vein. NOS3 is localized in vascular regions of portal spaces and centrolobulillar veins and in preserved sinusoids and although its expression is greater than in control animals (34%), it is clearly lower (50%) than 17 days after BDL. The time after BDL is crucial in the study of NO production, intrahepatic localization of NOS isoforms expression, and cell type involved, since all these parameters change with time. BDL-induced, peroxidation and fibrosis are not ligated by a cause-effect relationship, but rather they both seem to be the consequence of common inductors.

[Effects of antisense transforming growth factor beta receptor-II (TGFbetaRII) expressing plasmid on experimental liver fibrosis]

OBJECTIVE

To study the effects of antisense transforming growth factor beta receptor-II (TGFbetaRII) expressing plasmid on experimental liver fibrosis.

METHODS

RT-Nest-PCR and gene recombinant techniques were used to construct the rat antisense TGFbetaRII recombinant plasmid which can be expressed in eukaryotic cells. Thirty-six male SD rats were randomly distributed into five groups: 10 in experimental liver fibrosis model induced by pig-serum as disease control group; 10 in antisense TGFbetaRII transfection as treatment group; 10 in pCDNA3 transfection as treatment control group and 6 in normal control group. The recombinant plasmid and empty vector (pCDNA3) were encapsulated by glycosyl-poly-L-lysine and then transducted into rats of pig serum-induced liver fibrosis model respectively. Expression of exogenous transfected plasmid was assessed by Northern blot, RT-PCR and Western blot. We also tested ELISA of serum TGF-beta1, the contents of hepatic hydroxyproline, immunohistochemistry of type I and III collagen, and VG staining for pathological study.

RESULTS

The antisense TGFbetaRII expressing plasmid could be well expressed in vivo, and could block the mRNA and protein expression of TGFbetaRII in the fibrotic liver induced by pig serum. Its expression also reduced the level of TGF-beta1 [antisense treatment group (23.16+/-3.13) ng/ml, disease control group (32.96+/-3.79) ng/ml; F=36.73, 0.01]. Compared with the disease control group, the contents of hepatic hydroxyproline [antisense treatment group (0.17+/-0.01) mg/g liver, disease control group (0.30+/-0.03) mg/g liver; F=15.48, 0.01] and the deposition of collagens type I and type III decreased in the antisense group (antisense treatment group collagen type I 650.26+/-51.51, collagen type III 661.58+/-55.28; disease control group type I 1209.44+/-116.60, collagen type III 1175.14+/-121.44; F values are 69.87, 70.46, 0.01). And its expression also improved the pathologic classification of liver fibrosis models (0.01).

CONCLUSION

The results demonstrate that TGF-beta plays a key role in liver fibrogenesis and the prevention of liver fibrosis by antisense TGFbetaRII recombinant plasmid intervention may be therapeutically useful.

How can transforming growth factor beta be targeted usefully to combat liver fibrosis?

Transforming growth factor beta-1 (TGF-beta 1) plays a pivotal role in tissue fibrogenesis. Understanding the factors that control resolution of fibrosis is critical to devising means to combat clinical fibrosis. Future challenges would include designing ways to block the fibrosis-specific actions of TGF-beta. Blockade of transforming growth factor beta (TGF-beta) activity in vivo in animal models has proven to be an effective means of inhibiting the fibrotic response to injury in various organs. Similarly, transgenic animals in which TGF-beta 1 expression is artificially enhanced show marked spontaneous fibrosis or increased fibrotic response to injury. TGF-beta is known to effect fibroplasias, not only by its well known action of increasing extracellular matrix synthesis but also by coordinately regulating key proteins which mediate connective tissue homeostasis. This includes down-regulation of interstitial collagenase and other matrix metalloproteinases and up-regulation of antiproteases such as tissue inhibitor of metalloproteinase I and plasminogen activator inhibitor. Whilst inhibition of TGF-beta activity appears to be well tolerated in rodents over several weeks, the ultimately lethal phenotype of TGF-beta 1 knockout mice warns us that this pluripotent cytokine is essential for normal health. Therefore, downstream pathways activated by TGF-beta, which might be specific for its fibrotic effects, might be more useful targets for human fibrotic disease therapy. For example, the TGF-beta response protein connective tissue growth factor may be a good target for antifibrotics but definitive evidence awaits development of suitable genetically modified animal models and specific inhibitors.

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

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

The effects of nitric oxide synthase blockers on mesenteric blood flow with bile duct ligation

BACKGROUND/AIMS

The aim of this study was to investigate the effects of nitric oxide synthesis inhibition by L-NNA (N-nitro-L-arginine) on mesenteric blood flow in bile duct ligated rats.

METHODOLOGY

Forty female Wistar rats were allocated into four groups. Only common bile duct (CBD) was dissected with midline laparotomy (sham operated), CBD is ligated for obstructive jaundice (OJ group), with CBD dissection, 20 mg/kg L-NNA was given i.p. during 14 days (sham + L-NNA group), after CBD ligation, 20 mg/kg L-NNA was given i.p. during 14 days (OJ + L-NNA group). At the end of the 14th day, the rats were re-anaesthesized, phenylephrine was administered within the left jugular vein and, arterial blood pressure monitorization was done via left carotid artery. Blood flow of the mesenteric artery (SMA) was also recorded. Resistance of the SMA was calculated and in addition, pressure responses to phenylephrine were detected. Histopathological examination of the liver and blood analyses were done.

RESULTS

The mean blood pressure levels of the rats with OJ were lower than the control group (P>0.05). Blood flow of the SMA and vascular resistance of the rats with OJ have no significant difference with other groups. In CBD ligated animals, mean blood pressure and mesenteric vascular resistance increased by L-NNA but there was no difference in mesenteric blood flow rate and vasoconstrictive response to phenylephrine. On microscopic examination of the liver with OJ, bile duct proliferation and minimal mononuclear reaction were observed which was not affected by L-NNA administration.

CONCLUSIONS

Hypotension, low systemic vascular resistance, and a reduced sensitivity to vasoconstrictors are features of cirrhosis. In obstructive jaundice impaired vascular responsiveness to vasoconstrictor stimuli like as cirrhosis was not observed and also there was no improvement by L-NNA on histopathologic findings and liver function tests.

Production of septal fibrosis of the liver by means of foreign protein injections into rats

Similarities and differences in antigenic humoral responses and electrophoretic patterns between Capillaria hepatica and pig-serum were investigated as a contribution to the understanding of hepatic fibrosis induced by the parenteral administration of foreign proteins. Only two out of 10 rats receiving repeated intraperitoneal injections of an extract of Capillaria hepatica-infected mouse liver presented septal hepatic fibrosis (20%). Under the same experimental conditions, 4 out of 9 rats (44.4%) developed septal fibrosis following whole pig-serum administration. Injections of normal mouse liver extracts did not result in hepatic fibrosis. Since a 100% septal fibrosis rate is observed in experimentally Capillaria hepatica-infected rats, it appeared that Capillaria hepatica products continuously released from inside the liver creates a much more effective fibrosis inducing mechanism than the parenteral administration of such factors. Thus, repeated peritoneal administration of a foreign protein to rats would not reveal the full fibrogenic potential it may have under natural conditions.