Molecular mechanism of the reversibility of hepatic fibrosis: with special reference to the role of matrix metalloproteinases

Effect of vitamin D supplementation in patients with chronic hepatitis C after direct-acting antiviral treatment: a randomized, double-blind, placebo-controlled trial

Background

Replacement of vitamin D (VD) among patients with chronic hepatitis C (CHC) before viral eradication has demonstrated a protective effect on serum markers associated with hepatic fibrogenesis. We therefore hypothesized that VD may facilitate further fibrosis amelioration following curative treatment with direct-acting antivirals (DAA).

Methods

This study was a randomized, double-blind, placebo-controlled trial conducted between February 2018 and August 2018. Patients with CHC and VD deficiency were randomized in a 1:1 ratio to either receive ergicalciferol or placebo over 6 weeks. Biochemical analysis indicators, including 25-hydroxyvitamin D (25(OH)D), fibrogenic markers [(transforming growth factor beta 1 (TGF-β1) and tissue inhibitors of matrix metalloproteinases 1 (TIMP-1)], and fibrolytic markers [matrix metalloproteinase 9 (MMP-9) and amino terminal type III procollagen peptide (P3NP)], were assessed at baseline and at 6 weeks. Serum 25(OH)D was analyzed by a chemiluminescence immunoassay. Serum hepatic fibrogenesis markers were measured using a quantitative sandwich enzyme-linked immunosorbent assay.

Results

Seventy-five patients with CHC and VD deficiency were randomly assigned to VD (n = 37) and placebo (n = 38) groups. At the end of the study, the mean serum 25(OH)D level had risen to a normal level in the VD group, but was still deficient in the placebo group (41.8 ±   9.1 vs. 18.1 ±  4.6 ng/mL, p < 0.001). Upon restoration of the VD level, there were no significant mean differences in the change from baseline for TGF-β1 (-0.6 ng/mL (95% confidence interval (95% CI) [-2.8-1.7]), p = 0.63), TIMP-1 (-5.5 ng/mL (95% CI [-26.4 -15.3]), p = 0.60), MMP-9 (122.9 ng/mL (95% CI [-69.0 -314.8]), p = 0.21), and P3NP (-0.1 ng/mL (95% CI [-2.4 -2.2]), p = 0.92) between the VD and placebo groups.

Conclusion

Short-term VD supplementation after DAA treatment in patients with CHC does not improve serum fibrogenesis markers and may not expedite the residual liver fibrosis healing process. Future studies are warranted to evaluate the long-term effect of VD supplementation on hepatic fibrosis regression.

Ursolic acid reverses liver fibrosis by inhibiting NOX4/NLRP3 inflammasome pathways and bacterial dysbiosis

Activation of the NOX4/NLRP3 inflammasome pathway has been associated with fibrosis in other organs. An imbalance in intestinal bacteria is an important driving factor of liver fibrosis through the liver-gut axis. This study aimed to explore whether the effect of ursolic acid (UA) on liver fibrosis was associated with the NOX4/NLRP3 inflammasome pathways and intestinal bacteria. Wild-type (WT), NLRP3-/-, and NOX4-/- mice and AP-treated mice were injected with CCI4 and treated with or without UA. The intestinal contents of the mice were collected and analyzed by 16S rRNA sequencing. UA alleviated liver fibrosis, which manifested as decreases in collagen deposition, liver injury, and the expression of fibrosis-related factors, and the expression of NOX4 and NLRP3 was significantly inhibited by UA treatment. Even after CCI4 injection, liver damage and fibrosis-related factors were significantly decreased in NLRP3-/-, NOX4-/-, and AP-treated mice. Importantly, the expression of NLRP3 was obviously inhibited in NOX4-/- and AP-treated mice. In addition, the diversity of intestinal bacteria and the abundance of probiotics in NLRP3-/- and NOX4-/- mice was significantly higher than those in WT mice, while the abundance of harmful bacteria in NLRP3-/- and NOX4-/- mice was significantly lower than that in WT mice. The NOX4/NLRP3 inflammasome pathway plays a crucial role in liver fibrosis and is closely associated with the beneficial effect of UA. The mechanism by which the NOX4/NLRP3 inflammasome pathway is involved in liver fibrosis may be associated with disordered intestinal bacteria.

Liuweiwuling tablets attenuate BDL-induced hepatic fibrosis via modulation of TGF-β/Smad and NF-κB signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Liuweiwuling (LWWL) tablets contain a six-herb Chinese formula and are commonly prescribed to facilitate nourishment of the liver and kidneys, clear away toxic materials and activate blood circulation. Administration of LWWL is well known for its protective effects on the liver and its capacity to confer long-term stability in patients exhibiting reduced transaminase levels. Clinical studies have reported that LWWL can also be used for the treatment of liver fibrosis with associated treatment regimens resulting in a concomitant reduction in transforming growth factor β1 (TGF-β1) levels in the serum of patients with hepatic fibrosis. TGF-β1 plays a prominent role in stimulating liver fibrogenesis and this effect is mediated by myofibroblasts (MFB) derived from hepatic stellate cells (HSCs). It is likely that this phenomenon underpins the antifibrotic effects associated with LWWL.

AIM

The purpose of this study was to investigate the antifibrotic effects and mechanisms pertaining to LWWL.

METHODS

Hepatic fibrosis was induced in rats following bile duct ligation (BDL). Rats that underwent BDL received daily gavage administration of colchicine (0.2mg/kg per day), LWWL (0.4, 1.6, 6.4g/kg per day) or PBS (for the control group). Pathological changes in hepatic tissue were examined using hematoxylin and eosin (HE) and sirius red staining. Immunohistochemical analysis was performed to monitor α-SMA and type I collagen (Collagen I) protein expression. Real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blot analyses were used to monitor the expression of genes and proteins in the TGF-β/Smad signaling pathway, including TGF-β1, bone morphogenic protein and activin membrane-bound inhibitor (Bambi), Smad3, phosphorylated Smad3 (p-Smad3) and Smad7. We also monitored the expression of genes and proteins in the nuclear factor-κB (NF-κB) signaling pathway, including NF-κB p65, IκBα and phosphorylation of IκBα (p-IκBα), tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6) and interleukin 1β (IL-1β).

RESULTS

LWWL dose-dependently inhibited BDL-induced liver injury and hepatic fibrosis in rats. Furthermore, LWWL reduced liver tissue collagen deposition, hydroxyproline content, liver dysfunction and α-SMA expression in BDL-induced hepatic fibrosis rats. Moreover, LWWL markedly prevented activation of the TGF-β/Smad signaling pathway by inhibiting expression of Smad2/3 and phosphorylation of Smad3, and upregulating the expression of Bambi and Smad7. In addition, LWWL regulated the expression of the inflammatory cytokines IL-1β, TNF-α and IL-6 by inhibiting the activation of NF-κB p65 and the phosphorylation of IκBα, and increasing the expression of IκBα.

CONCLUSIONS

LWWL can attenuate BDL-induced hepatic fibrosis in rats, and this effect may be due to modulation of the NF-κB-dependent inflammatory response and activation of HSC and TGF-β/Smad-mediated synthesis and degradation of Collagen I.

Effects of exogenous thymosin β4 on carbon tetrachloride-induced liver injury and fibrosis

The present study investigated the effects of exogenous thymosin β4 (TB4) on carbon tetrachloride (CCl₄)-induced acute liver injury and fibrosis in rodent animals. Results showed that both in mice and rats CCl₄ rendered significant increases in serum alanine aminotransferase and aspartate aminotransferase, hepatic malondialdehyde formation, decreases in antioxidants including superoxide dismutase and glutathione, and up-regulated expressions of transforming growth factor-β1, α-smooth muscle actin, tumor necrosis factor-α and interleukin-1β in the liver tissues. Hydroxyproline contents in the rat livers were increased by CCl₄. Histopathological examinations indicated that CCl₄ induced extensive necrosis in mice livers and pseudo-lobule formations, collagen deposition in rats livers. However, all these changes in mice and rats were significantly attenuated by exogenous TB4 treatment. Furthermore, up-regulations of nuclear factor-κB p65 protein expression by CCl₄ treatment in mice and rats livers were also remarkably reduced by exogenous TB4 administration. Taken together, findings in this study suggested that exogenous TB4 might prevent CCl₄-induced acute liver injury and subsequent fibrosis through alleviating oxidative stress and inflammation.

Novel 5-arylthio-5H-chromenopyridines as a new class of anti-fibrotic agents

Liver fibrosis is a critical wound healing response to chronic liver injury such as hepatitis C virus (HCV) infection. If persistent, liver fibrosis can lead to cirrhosis and hepatocellular carcinoma (HCC). The development of new therapies for preventing liver fibrosis and its progression to cancer associated with HCV infection remains a critical challenge. Identification of novel anti-fibrotic compounds will provide opportunities for innovative therapeutic intervention of HCV-mediated liver fibrosis. We designed and synthesized a focused set of 5-arylthio-5H-chromenopyridines as a new class of anti-fibrotic agents. Liver fibrosis assays demonstrated that the compounds 3a and 3c show inhibitory activity towards human hepatic stellate cells (LX2) activation at 10μM. The HCV NS3 and NS5A proteins in HCV subgenome-expressing cells were also significantly reduced in cells treated with 3a and 3c, suggesting the possible inhibitory role of the compounds in HCV translation/replication activities. We have also examined the reactivity of these compounds with medicinally-relevant metal compounds such as platinum and gold. The reactivity of these complexes with metals and during Mass Spectrometry suggests that CS bond cleavage is relatively facile.

Gossypol ameliorates liver fibrosis in diabetic rats induced by high-fat diet and streptozocin

11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) inhibitors have been shown to treat type 2 diabetes (T2D). Since gossypol is an 11β-HSD1 inhibitor, the objective of the present study was to treat T2D and T2D-related liver fibrosis in rat model using low-dose gossypol. T2D was induced by feeding with high fat diet plus injection of streptozocin (30mg/kg). Diabetic rats were treated with either vehicle control or racemic gossypol with a dose of 15mg/kg/day for 4weeks followed by 15mg/kg/week for additional 8weeks. Blood glucose, cholesterol, LDL, and triglycerides were measured. Messenger mRNA levels of glucocorticoid receptor (Nr3c1), phosphoenolpyruvate carboxykinase (Pck1), glucose-6-phosphatase (G6pc), collagen I (Col1a1), collagen III (Col3a1), fibronectin (Fn1), tissue inhibitor of metalloproteinase 1 (Timp1), and 2 (Timp2) were measured. T2D rats had higher serum glucose, cholesterol, LDL, and triglyceride levels compared to control. Liver Nr3c1, Col1a1, Col3a1, Fn1, Timp1, and Timp2 were increased in T2D rats. T2D liver showed significant fibrosis with the increases of α-smooth muscle actin and fibronectin. After gossypol treatment, serum glucose level was lowered by 64%. Liver fibrosis was significantly ameliorated. Nr3c1, Col1a1, Col3a1, Fn1, Timp1, Timp2, Pck1 as well as G6pc levels were significantly reduced. In conclusion, low dose gossypol is effective for the treatment of T2D and T2D-related fibrosis.

Effects of silymarin and pentoxifylline on matrix metalloproteinase-1 and -2 expression and apoptosis in experimental hepatic fibrosis

BACKGROUND

Many therapeutic strategies have been proposed to treat liver fibrosis, but no drugs have been proved effective. Matrix metalloproteinases (MMPs) have been reported to play a role in some cellular cascades of hepatic inflammation and fibrosis.

OBJECTIVE

The purpose of this study was to investigate whether silymarin and pentoxifylline (PTX) have hepatoprotective and antifibrotic effects in experimental hepatic fibrosis.

METHODS

Sprague-Dawley rats were divided into 4 groups: silymarin group (silymarin 4 mg/kg · d(-1) orally, common bile duct ligation [CBDL]); PTX group (PTX 2 mg/kg · d(-1) intraperitoneally, CBDL); sham group (common bile duct [CBD] exploration only); and control group (saline 1 mL/d orally, CBDL). The CBD was explored and dissected sufficiently to allow passage of a 3/0 silk suture via midline laparotomy. On day 10, all animals were euthanized via cervical dislocation. Then, 5-cm(3) liver samples from the right lobe were removed for histomorphologic evaluation and 3-mL blood samples were taken via cardiac puncture for biochemical analyses. Apoptosis was determined using the terminal deoxynucleotidyltransferase-biotin nick end-label (TUNEL) staining method. Plasma levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and γ-glutamyltransferase; total and indirect bilirubin concentration; hepatic MMP-1 and -2 and tissue inhibitor of MMP (TIMP)-l and -2 activity; and transforming-growth factor (TGF)-β1 concentration were measured. Collagen content was determined by measuring hydroxyproline in liver samples. Malondialdehyde (MDA) was used to estimate lipid peroxidation.

RESULTS

Thirty-two adult male Sprague-Dawley rats were divided into 4 groups: silymarin group (n = 7), PTX group (n = 7), sham group (n = 9), and control group (n = 9). Compared with the control group (14.6 [2.44]), mean (SD) hepatocyte apoptosis (as measured by the ratio of TUNEL-positive cells) was significantly suppressed in the silymarin group (1.2 [0.13]; P = 0.001) and the PTX group (3.8 [0.34]; P = 0.001). Mean (SD) MMP-2 activity in the silymarin group (57.35 [9.89] μg/mL; P = 0.04) and the PTX group (46.88 [9.56] μg/mL; P = 0.04) was significantly lower than that observed in the control group (232.32 [79.76] μg/mL). Compared with the control group (1.37 [0.38] μg/mL), TIMP-2 activity was significantly lower in the silymarin group (0.55 [0.13] μg/mL; P = 0.04) and the PTX group (0.42 [0.09] μg/mL; P = 0.01). Compared with the control group (909.17 [117.35] μg/mL), TGF-β1 was significantly lower in the silymarin group (518.24 [30.34] μg/mL; P = 0.01) and the PTX group (519.57 [47.27] μg/mL; P = 0.01). Histomorphologic changes were significantly greater in the sham group than in the silymarin and PTX groups: hemorrhage (2.44 [0.29] vs 1.29 [0.18] and 1.57 [0.20], respectively; both, P = 0.04); sinusoidal dilatation (2.22 [0.22] vs 1.57 [0.20] and 1.71 [0.18]; both, P = 0.04); presinusoidal polymorphonuclear cell infiltration (3-44 [0.24] vs 2.57 [0.20] and 2.14 [0.26]; P = 0.03 and P = 0.008, respectively); and inflammation (3.44 [0.24] vs 2.57 [0.20] and 2.14 [0.26]; P = 0.03 and P = 0.008, respectively). In the control group, all biochemical markers were elevated, supporting the presence of liver injury. Compared with the control group (630.00 [46.80] U/L), plasma AST activity was significantly lower in the silymarin group (443.11 [78.73]; P = 0.04) and the PTX group (349.42 [34.00]; P = 0.03). Compared with the control group (191.12 [32.93] U/L), plasma ALT activity was significantly lower in the silymarin group (86.14 [4.97]; P = 0.04) and the PTX group (84.14 [11.21]; P = 0.04). MDA concentration was significantly lower in the silymarin group compared with the control group (0.08 [0.01] vs 0.22 [0.03] nmol/mL; P = 0.004); MDA was also significantly lower in the silymarin group than in the PTX group (0.11 [0.02]; P = 0.03).

CONCLUSIONS

Silymarin and PTX were associated with lower histopathologic liver damage, hepatocyte apoptosis, and regulation of extracellular matrix proteins. Lipid peroxidation in hepatocytes was significantly lower in the silymarin group compared with the PTX group. Silymarin and PTX appeared to have hepatoprotective effects in this experimental liver fibrosis model, but further clinical and experimental studies are needed.

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

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

Antifibrotic effects of a recombinant adeno-associated virus carrying small interfering RNA targeting TIMP-1 in rat liver fibrosis

Elevated tissue inhibitor of metalloproteinase 1 (TIMP-1) expression contributes to excess production of extracellular matrix in liver fibrosis. Herein, we constructed a recombinant adeno-associated virus (rAAV) carrying siRNA of the TIMP-1 gene (rAAV/siRNA-TIMP-1) and investigated its effects on liver fibrosis in rats. Two models of rat liver fibrosis, the carbon tetrachloride and bile duct ligation models, were treated with rAAV/siRNA-TIMP-1. In the carbon tetrachloride model, rAAV/siRNA-TIMP-1 administration attenuated fibrosis severity, as determined by histologic analysis of hepatic collagen accumulation, hydroxyproline content, and concentrations of types I and III collagen in livers and sera. Levels of mRNA and active matrix metalloproteinase (MMP) 13 were elevated, whereas levels of mRNA and active MMP-2 were decreased. Moreover, a marked decrease was noted in the expression of α-smooth muscle actin, a biomarker of activated hepatic stellate cells (HSCs), and transforming growth factor-β1, critical for the development of liver fibrosis. Similarly, rAAV/siRNA-TIMP-1 treatment significantly alleviated bile duct ligation-induced liver fibrosis. Furthermore, this treatment dramatically suppressed TIMP-1 expression in HSCs from both model rats. These data indicate that the administration of rAAV/siRNA-TIMP-1 attenuated liver fibrosis by directly elevating the function of MMP-13 and diminishing activated HSCs. It also resulted in indirect decreased expression of type I collagen, MMP-2, and transforming growth factor-β1. In conclusion, rAAV/siRNA-TIMP-1 may be an effective antifibrotic gene therapy agent.

Effect of sinapic acid against dimethylnitrosamine-induced hepatic fibrosis in rats

Sinapic acid is a member of the phenylpropanoid family and is abundant in cereals, nuts, oil seeds, and berries. It exhibits a wide range of pharmacological properties. In this study, we investigated the hepatoprotective and antifibrotic effects of sinapic acid on dimethylnitrosamine (DMN)-induced chronic liver injury in rats. Sinapic acid remarkably prevented DMN-induced loss of body weight. This was accompanied by a significant increase in levels of serum alanine transaminase, aspartate transaminase, and liver malondialdehyde content. Furthermore, sinapic acid reduced hepatic hydroxyproline content, which correlated with a reduction in the expression of type I collagen mRNA and histological analysis of collagen in liver tissue. Additionally, the expression of hepatic fibrosis-related factors such as α-smooth muscle actin and transforming growth factor-β1 (TGF-β1), were reduced in rats treated with sinapic acid. Sinapic acid exhibited strong scavenging activity. In conclusion, we find that sinapic acid exhibits hepatoprotective and antifibrotic effects against DMN-induced liver injury, most likely due to its antioxidant activities of scavenging radicals, its capacity to suppress TGF-β1 and its ability to attenuate activation of hepatic stellate cells. This suggests that sinapic acid is a potentially useful agent for the protection against liver fibrosis and cirrhosis.

Evaluation of the spontaneous reversibility of carbon tetrachloride-induced liver cirrhosis in rabbits

There is a general consensus that liver fibrosis in humans is potentially reversible, while scepticism prevails on the concept that cirrhosis can be truly reversed. The availability of suitable experimental models is fundamental for disease research. The experimental murine model of liver cirrhosis induced by carbon tetrachloride (CCl(4)) reproduces both the histological picture of the postnecrotic cirrhosis and its biochemical and clinical parameters. Normal hepatic structure is modified by formation of regeneration nodules. Fibrosis represents a morphological element of disease and an effect of hepatocyte necrosis. However, the relevance for research of this well-established model of liver cirrhosis is hampered by some spontaneous cirrhosis regression reported in mice and rats. It has been reported that CCl(4) also induces experimental liver cirrhosis in rabbits, but it is not known whether the process is reversible in this species. The aim of our study was to investigate this question. Male New Zealand White rabbits were treated intragastrically with CCl(4) or the vehicle only for 19 weeks and groups were sacrificed three and five months after treatment interruption. Cirrhotic and control livers were processed for routine light microscopy and for morphometric study of fibrosis by semiquantitative evaluation. The degree of fibrosis was based on the Knodell's scoring system.

Rapid temporal changes in the expression of a set of neuromodulatory genes during alcohol withdrawal in the dorsal vagal complex: molecular evidence of homeostatic disturbance

BACKGROUND

Chronic alcohol exposure produces neuroadaptation, which increases the risk of cellular excitotoxicity and autonomic dysfunction during withdrawal. The temporal progression and regulation of the gene expression that contributes to this physiologic and behavioral phenotype is poorly understood early in the withdrawal period. Further, it is unexplored in the dorsal vagal complex (DVC), a brainstem autonomic regulatory structure.

METHODS

We use a quantitative polymerase chain reaction platform to precisely and simultaneously measure the expression of 145 neuromodulatory genes in more than 100 rat DVC samples from control, chronically alcohol-exposed, and withdrawn rats. To gain insight into the dynamic progression and regulation of withdrawal, we focus on the expression of a subset of functionally relevant genes during the first 48 hours, when behavioral symptoms are most severe.

RESULTS

In the DVC, expression of this gene subset is essentially normal in chronically alcohol-exposed rats. However, withdrawal results in rapid, large-magnitude expression changes in this group. We observed differential regulation in 86 of the 145 genes measured (59%), some as early as 4 hours into withdrawal. Time series measurements (4, 8, 18, 32, and 48 hours after alcohol removal) revealed dynamic expression responses in immediate early genes, γ-aminobutyric acid type A, ionotropic glutamate, and G-protein coupled receptors and the Ras/Raf signaling pathway. Together, these changes elucidate a complex, temporally coordinated response that involves correlated expression of many functionally related groups. In particular, the expression patterns of Gabra1, Grin2a, Grin3a, and Grik3 were tightly correlated. These receptor subunits share overrepresented transcription factor binding sites for Pax-8 and other transcription factors, suggesting a common regulatory mechanism and a role for these transcription factors in the regulation of neurotransmission within the first 48 hours of alcohol withdrawal.

CONCLUSIONS

Expression in this gene set is essentially normal in the alcohol-adapted DVC, but withdrawal results in immediate, large-magnitude, and dynamic changes. These data support both increased research focus on the biological ramifications of alcohol withdrawal and enable novel insights into the dynamic withdrawal expression response in this understudied homeostatic control center.

Protective effects of total flavonoids of Bidens bipinnata L. against carbon tetrachloride-induced liver fibrosis in rats

Bidens bipinnata L. is well known in China as a traditional Chinese medicine and has been used to treat hepatitis in clinics for many years. In a previous study we found that total flavonoids of Bidens bipinnata L. (TFB) had a protective effect against carbon tetrachloride (CCl4)-induced acute liver injury in mice. Now this study was designed to investigate its therapeutic effect against CCl4-induced liver fibrosis in rats and to determine, in part, its mechanism of action. The liver fibrosis model was established by subcutaneous injection of 50% CCl4 twice a week for 18 weeks. TFB (40, 80 and 160 mg kg(-1)) was administered by gastrogavage daily from the 9th week. The results showed that TFB (80 and 160 mg kg(-1)) treatment for 10 weeks significantly reduced the elevated liver index (liver weight/body weight) and spleen index (spleen weight/body weight), elevated levels of serum transaminases (alanine aminotransferase and aspartate aminotransferase), hyaluronic acid, type III procollagen and hepatic hydroxyproline. In addition, TFB markedly inhibited CCl4-induced lipid peroxidation and enhanced the activity of the antioxidant enzymes superoxide dismutase and glutathione peroxidase. Moreover, TFB (80 and 160 mg kg(-1)) treatment improved the morphologic changes of hepatic fibrosis induced by CCl4 and suppressed nuclear factor (NF)-kappaB, alpha-smooth muscle actin (SMA) protein expression and transforming growth factor (TGF)-beta1 gene expression in the liver of liver fibrosis of rats. In conclusion, TFB was able to ameliorate liver injury and protect rats from CCl4-induced liver fibrosis by suppressing oxidative stress. This process may be related to inhibiting the induction of NF-kappaB on hepatic stellate cell activation and the expression of TGF-beta1.

Time profiles of the expression of metalloproteinases, tissue inhibitors of metalloproteases, cytokines and collagens in hamsters infected with Opisthorchis viverrini with special reference to peribiliary fibrosis and liver injury

The liver fluke Opisthorchis viverrini is endemic in southeastern Asia, and causes cholangiocarcinoma and liver fibrosis. We investigated the time profile of the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) in relation to peribiliary fibrosis in O. viverrini-infected hamsters. Hepatic mRNA expression of MMPs, TIMPs, cytokines and collagens I and III was assessed by quantitative reverse transcription-PCR. Zymography and immunohistochemistry were also used to examine MMPs-2 and -9 expression. After infection, an increase of peribiliary fibrosis was time-dependent. Opisthorhis viverrini-induced gene expression in hamster liver, with increased mRNA expression levels of IL-1beta, TNF-alpha, TGF-beta, and collagens I and III, was observed at 21 days p.i. Expression of MMPs-2, -13 and -14 and TIMPs-1 and -3 genes, was significantly higher at 1 month, and maximal levels of most MMPs (MMPs-2, -9, -13 and -14) were observed at 2 months p.i. The cytoplasmic levels of MMP-2 and MMP-9 were similar to mRNA expression. Immunohistochemistry revealed that MMP-9 was expressed mainly in the cytoplasm of inflammatory cells at the invasive front of the fibrous area. In contrast, the highest levels of mRNA expression of TIMPs-2 and -3, and TGF-beta were observed 10 months p.i. Concentration of TIMP-2 protein in the plasma correlated with its transcriptional level (r=0.320, P=0.040). Peribiliary fibrosis correlated positively with liver hydroxyproline content (r=0.846, P<0.001), plasma hydroxyproline concentration (r=0.770, P<0.001), plasma TIMP-2 level (r=0.335, P=0.046), and mRNA expression levels of MMP-7 (r=0.511, P=0.006), TIMP-1 (r=0.320, P=0.040), TIMP-2 (r=0.428, P=0.026), and TIMP-3 (r=0.553, P=0.003). This study suggests that expression of MMPs is associated with an inflammatory reaction in the early phase and TIMPs expression at the late phase may contribute to both fibrosis and liver injury. MMPs and TIMPs may serve as diagnostic markers for the severity of O. viverrini-induced liver injury.

Role of Kupffer cells in hepatic fibrosis

Kupffer cells (KC), a kind of nonparenchymal cells and defenders in the liver, release various chemical mediators to induce liver injury, and play an important role in many pathologic changes of the liver. Hepatic fibrosis is the common pathologic process of varied chronic liver diseases, and it is also a "transfer station" for many chronic liver diseases lapsing to cirrhosis. As important influencing factors, cytokines secreted by KC are involved in the occurrence and progression of hepatic fibrosis. Therefore, lucubrating the role and mechanism of KC in the progression of hepatic fibrosis, and investigating the KC-related therapeutic strategies of anti-fibrosis have practical significances for the prevention and treatment of liver injury and the raise of patients' survival rates in clinical practice.

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

BACKGROUND AND AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Oxidative stress and matrix metalloproteinase-9 activity in the liver after hypoxia and reoxygenation with 21% or 100% oxygen in newborn piglets

We designed a randomized controlled study to identify and compare the liver tissue responses in systemic hypoxia and resuscitation with 21% and 100% oxygen using an animal model of neonatal hypoxia and reoxygenation. Twenty-seven piglets (1-3 days old, weight 1.5-2.0 kg) were acutely instrumented and mechanically ventilated. The animals underwent 2 h of normocapnic alveolar hypoxia (10-15% oxygen) then reoxygenation with 21% or 100% oxygen for 1 h, then 1 h with 21% oxygen. Controls were sham-operated without hypoxia-reoxygenation. After 2 h of reoxygenation liver tissue samples were immediately processed for histological and biochemical analyses of markers of oxidative stress and tissue injury. Two hours of hypoxia caused a significant reduction in mean arterial pressure with cardiogenic shock and metabolic acidemia, with similar recovery upon resuscitation with 21% and 100% oxygen. After 2 h of reoxygenation, the hepatic GSSG:total glutathione ratio and matrix metalloproteninase-9 activity, which correlated with the portal venous oxygenation at 15 min of reoxygenation, were greater in the 100% group and hepatic lactate level was higher in the 21% group than the controls (all P<0.05). Both hypoxic-reoxygenated groups had similarly elevated hepatic Bcl-2 levels. Apart from more non-distinct mitochondria identified in the 100% group, hepatic tissue adenylate energy charge and plasma transaminases levels did not differ among groups. We concluded that in this acute model of neonatal hypoxia and reoxygenation, resuscitation using 21% oxygen avoids the excess oxidative stress and elevated matrix metalloproteninase-9 activity in the liver when 100% oxygen was used. The study supports the conservative use of oxygen in optimizing post-hypoxic hepatic recovery.

Protection by and anti-oxidant mechanism of berberine against rat liver fibrosis induced by multiple hepatotoxic factors

1. The aim of the present study was to investigate the effect and mechanism of berberine, an alkaloid extracted from the traditional Chinese medicine coptis, on rat liver fibrosis induced by multiple hepatotoxic factors. 2. Male Wistar rats were separated into five groups, a normal control group, a fibrotic control group and fibrotic groups treated with three different doses of berberine. The fibrotic models were established by introduction of multiple hepatotoxic factors, including CCl(4), ethanol and high cholesterol. Rats in the treatment groups were administered 50, 100 or 200 mg/kg berberine, intragastrically, daily for 4 weeks. Serum levels of alanine aminotransferase (ALT) and serum aspartate aminotransferase (AST), hepatic activity of superoxide dismutase (SOD) and hepatic malondialdehyde (MDA) and hepatic hydroxyproline (Hyp) content were determined. Liver biopsies were obtained for histological and immunohistochemical studies to detect the expressions of alpha-smooth muscle actin (SMA) and transforming growth factor (TGF)-beta1. 3. The results showed that, compared with the fibrotic control group, serum levels of ALT and AST and hepatic content of MDA and Hyp were markedly decreased, but the activity of hepatic SOD was significantly increased in berberine-treated groups in a dose-dependent manner. In addition, histopathological changes, such as steatosis, necrosis and myofibroblast proliferation, were reduced and the expression of a-SMA and TGF-b1 was significantly downregulated in the berberine-treated groups (P < 0.01). 4. These results suggest that berberine could be used to prevent experimental liver fibrosis through regulation of the anti-oxidant system and lipid peroxidation.

Modified synthetic siRNA targeting tissue inhibitor of metalloproteinase-2 inhibits hepatic fibrogenesis in rats

BACKGROUND/AIMS

Fibrosis occurs in most chronic liver injuries and results from changes in the balance between synthesis and degradation of extracellular matrix (ECM) components. Matrix metalloproteinases (MMPs) and their endogenous inhibitors (TIMPs) are known to regulate the ECM turnover. We investigate the effect of modified synthetic small interfering RNA (siRNA) targeting TIMP-2 in rat model of liver fibrosis.

METHODS

Rat hepatic fibrosis was induced by CCl4 for 8 weeks. After the 2-week CCl4 injection period, rats in the three siRNA groups simultaneously received a different dosage (0.05, 0.1 and 0.2 mg.kg(-1), respectively) of modified synthetic siRNA targeting TIMP-2 via the tail vein every 3 days for 6 weeks. The pathological changes in liver tissues were observed by light microscopy and transmission electron microscopy. Portal vein pressure and proliferating cell nuclear antigen were measured. Expression of TIMP-2, MMP-2, MT1-MMP, MMP-13, hepatocyte growth factor, collagen type I, collagen type III and alpha-SMA were evaluated by quantitative real-time polymerase chain reaction or Western blotting or gelatin zymography.

RESULTS

Modified synthetic siRNA targeting TIMP-2 induced a dose-dependent inhibition of the TIMP-2 expression in the rat model of liver fibrosis with a similar trend in MMP-2 and MT1-MMP, but an increase in MMP-13. Rats administered siRNA targeting TIMP-2 showed promotion of ECM degradation, reduction in activated hepatic stellate cells and enhancement of hepatocyte regeneration. Furthermore, portal hypertension was also ameliorated after treatment with siRNA targeting TIMP-2.

CONCLUSIONS

Knock-down of TIMP-2 expression attenuates CCl4-induced liver fibrosis and is a potential pharmacological target for gene therapy in liver fibrosis.

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

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

Inhibitory effects of saikosaponin-d on CCl4-induced hepatic fibrogenesis in rats

AIM: To investigate the suppressive effect of saikosaponin-d (SSd) on hepatic fibrosis in rats induced by CCl₄ injections in combination with alcohol and high fat, low protein feeding and its relationship with the expression of nuclear factor-κB (NF-κB), tumor necrosis factor-alpha (TNF-α) and interleukins-6 (IL-6).

METHODS: Hepatic fibrosis models were induced by subcutaneous injection of CCl₄ at a dosage of 3 mL/kg in rats. At the same time, rats in treatment groups were injected intraperitoneally with SSd at different doses (1.0, 1.5 and 2.0 mg/kg) once daily for 6 wk in combination with CCl₄, while the control group received olive oil instead of CCl₄. At the end of the experiment, rats were anesthetized and killed (except for 8 rats which died during the experiment; 2 from the model group, 3 in high-dose group, 1 in medium-dose group and 2 in low-dose group). Hematoxylin and eosin (HE) staining and Van Gieson staining were used to examine the changes in liver pathology. The levels of alanine aminotransferase (ALT), triglyeride (TG), albumin (ALB), globulin (GLB), hyaluronic acid (HA) and laminin (LN) in serum and the content of hydroxyproline (HYP) in liver were measured by biochemical examinations and radioimmuneoassay, respectively. In addition, the expression of TNF-α and IL-6 in liver homogenate was evaluated by enzyme-linked immunosorbent assay (ELISA) and the levels of NF-κBp65 and I-κBα in liver tissue were analyzed by Western blotting.

RESULTS: Both histological examination and Van Gieson staining demonstrated that SSd could attenuate the area and extent of necrosis and reduce the scores of liver fibrosis. Similarly, the levels of ALT, TG, GLB, HA, and LN in serum, and the contents of HYP, TNF-α and IL-6 in liver were all significantly increased in model group in comparison with those in control group. Whereas, the treatment with SSd markedly reduced all the above parameters compared with the model group, especially in the medium group (ALT: 412 ± 94.5 IU/L vs 113.76 ± 14.91 IU/L, TG: 0.95 ± 0.16 mmol/L vs 0.51 ± 0.06 mmol/L, GLB: 35.62 ± 3.28 g/L vs 24.82 ± 2.73 g/L, HA: 42.15 ± 8.25 ng/mL vs 19.83 ± 3.12 ng/mL, LN: 27.56 ± 4.21 ng/mL vs 13.78 ± 2.57 ng/mL, HYP: 27.32 ± 4.32 μg/mg vs 16.20 ± 3.12 μg/mg, TNF-α: 4.38 ± 0.76 ng/L vs 1.94 ± 0.27 ng/L, IL-6: 28.24 ± 6.37 pg/g vs 12.72 ± 5.26 pg/g, respectively, P < 0.01). SSd also decreased ALB in serum (28.49 ± 4.93 g/L vs 37.51 ± 3.17 g/L, P < 0.05). Moreover, the expression of NF-κB p65 in the liver of treated groups was lower than that in model groups while the expression of I-κBα was higher in treated group than in model group (P < 0.01). The expression of NF-κBp65 and TNF-α had a positive correlation with the level of HA in serum of rats after treatment with CCl₄ (r = 0.862, P < 0.01; r = 0.928, P < 0.01, respectively).

CONCLUSION: SSd attenuates CCl₄-induced hepatic fibrosis in rats, which may be related to its effects of hepato-protective and anti-inflammation properties, the down-regulation of liver TNF-α, IL-6 and NF-κBp65 expression and the increased I-κBα activity in liver.

Thalidomide prevents rat liver cirrhosis via inhibition of oxidative stress

This study investigated the effect of thalidomide on oxidative stress in rat liver cirrhosis. The cirrhosis of rat was induced by intraperitoneal injection of carbon tetrachloride thrice weekly; meanwhile, thalidomide (10mg/kg or 100mg/kg) was given daily by intragastric administration for 8 weeks. The content of oxidative stress parameters, including superoxide dismutase, glutathione peroxidase, and malondialdehyde, in the liver was detected by biochemical assay. Immunohistochemistry revealed alpha-smooth muscle actin (alpha-SMA), desmin, and tissue inhibitor of metalloproteinase-1 (TIMP-1) protein in the liver. Nuclear factor kappa B p65 (NF-kappaBp65) protein in nucleus and transforming growth factor beta1 (TGF-beta1) protein in cytoplasm were detected by Western blot. NF-kappaBp65, TGF-beta1, and TIMP-1 mRNA levels in the liver were studied using reverse transcriptase polymerase chain reaction. Liver histopathology was significantly improved in rats given high doses of thalidomide. The content of oxidative stress parameters and the expressions of NF-kappaBp65, TGF-beta1 and TIMP-1 protein, and mRNA were significantly decreased in these animals. The expressions of alpha-SMA and Desmin protein were also significantly decreased in them. Thalidomide might exert an effect on the inhibition of oxidative stress via downregulation of NF-kappaB signaling pathway to prevent the progression of liver cirrhosis.

Alpha-melanocyte-stimulating hormone gene therapy reverses carbon tetrachloride induced liver fibrosis in mice

BACKGROUND

Hepatic fibrosis represents a process of healing and scarring in response to chronic liver injury. Effective therapies are lacking. We have previously demonstrated that alpha-melanocyte-stimulating hormone (alpha-MSH) gene therapy protects against thioacetamide-induced acute liver failure in mice. Recent reports showed that collagen metabolism is a novel target of alpha-MSH. Therefore, the aim of this study is to investigate whether alpha-MSH gene therapy possesses anti-hepatic fibrogenic effect in mice.

METHODS

Liver fibrosis was induced in mice by administering carbon tetrachloride (CCl4) continuously for 10 weeks. Alpha-MSH expression plasmid was delivered via electroporation after liver fibrosis had been established. Histopathology, reverse-transcription polymerase chain reaction (RT-PCR), immunoblotting, and gelatin zymography were used to investigate its possible mechanisms of action.

RESULTS

Alpha-MSH gene therapy reversed established liver fibrosis in CCl4-treated mice. RT-PCR revealed that alpha-MSH gene therapy attenuated the liver TGF-beta1, collagen alpha1, and cell adhesion molecule mRNA upregulation. Following gene transfer, both the activation of alpha-smooth muscle actin (alpha-SMA) and cyclooxygenase-2 (COX-2) was significantly attenuated. Further, alpha-MSH significantly increased matrix metalloproteinase (MMP) activity with tissue inhibitors of matrix metalloproteinase (TIMP) inactivation.

CONCLUSIONS

We have demonstrated that alpha-MSH gene therapy reversed established liver fibrosis in mice. It also prevented the upregulated fibrogenic and proinflammatory gene response after CCl4 administration. Its collagenolytic effect may be attributed to MMP and TIMP modulation. In summary, alpha-MSH gene therapy may be an effective therapeutic modality against liver fibrosis with potential clinical use.

Molecular biology of ADAMTS13 and diagnostic utility of ADAMTS13 proteolytic activity and inhibitor assays

ADAMTS13, a reprolysin-like metalloprotease, limits platelet-rich thrombus formation in the small arteries by cleaving von Willebrand factor (vWF) at the Tyr1605-Met1606 peptide bond. Deficiency of plasma ADAMTS13 activity, due to either an inherited or an acquired etiology, may lead to a potentially lethal syndrome, thrombotic thrombocytopenic purpura (TTP). Molecular cloning and characterization of the ADAMTS13 gene have provided further insight into the structure-function relationships, biosynthesis, and regulation of the ADAMTS13 protease, in addition to understanding the pathogenesis of TTP and perhaps other thrombotic disorders. ADAMTS13 consists of a short propeptide, a typical reprolysin-like metalloprotease domain, followed by a disintegrin-like domain, first thrombospondin type 1 (TSP1) repeat, Cys-rich domain, and spacer domain. The carboxyl terminus of ADAMTS13 has seven more TSP1 repeats and two CUB domains. ADAMTS13 is synthesized mainly in hepatic stellate cells, but also in vascular endothelial cells. Recognition and cleavage of vWF require the proximal carboxyl terminal domains, but not the middle and distal carboxyl terminal domains. Cleavage of vWF appears to be modulated by shear force, binding to platelet or platelet glycoprotein-1balpha, heparin, inflammatory cytokine (interleukin-6), and chloride ion. At the site of thrombus formation, the ADAMTS13 may be inactivated by thrombin, plasmin, and factor Xa. Having a sensitive and specific assay for ADAMTS13 activity is not only critical to understand the basic biology of ADAMTS13 protease, but also to facilitate a more timely and accurate clinical diagnosis of TTP, and to initiate potentially life-saving plasma exchange therapy. Although many assays have been developed and tested for clinical applications, the fluorescent resonance energy transfer-vWF73 assay appears to be the simplest and most promising assay to date.

Increased ADAMTS-13 proteolytic activity in rat hepatic stellate cells upon activation in vitro and in vivo

INTRODUCTION

ADAMTS-13 is a member of A Disintegrin And Metalloprotease with ThromboSpondin type 1 repeats (ADAMTS) family, primarily synthesized in hepatic stellate cells (HSCs), one of the major cell types transdifferentiating into myofibroblasts during liver fibrosis. However, the association between ADAMTS-13 expression and HSC activation or liver fibrosis is not known.

METHODS

In this study, we determined the ADAMTS-13 mRNA, protein, and activity in isolated primary HSCs upon activation on a plastic dish and in liver after administration of carbon tetrachloride (CCl(4)) in rats.

RESULTS

We showed that ADAMTS-13 antigen and proteolytic activity in the activated rat HSCs were dramatically increased, whereas ADAMTS-13 mRNA in these cells was only minimally altered. Similarly, the ADAMTS-13 antigen and proteolytic activity in rat liver after CCl(4) injury were also significantly increased, whereas the ADAMTS-13 mRNAs in these liver tissues were only slightly increased compared with normal. Surprisingly, despite the dramatic up-regulation of ADAMTS-13 protein synthesis in the activated HSCs after CCl(4) administration, the plasma levels of ADAMTS-13 protease in rats did not increase concordantly.

CONCLUSION

We conclude that the up-regulation of ADAMTS-13 protein expression in rat HSCs during activation in vitro and in vivo suggests the possibility of ADAMTS-13 proteolysis, an important part of function of the activated HSCs, perhaps through modulation of liver regeneration or formation of liver fibrosis after various injuries. The data also suggest the minimal contribution of the activated HSCs in regulation of plasma levels of ADAMTS-13 protease.

Electroporative interleukin-10 gene transfer ameliorates carbon tetrachloride-induced murine liver fibrosis by MMP and TIMP modulation

AIM

Liver fibrosis represents a process of healing and scarring in response to chronic liver injury. Effective therapies for liver fibrosis are lacking. Interleukin-10 (IL-10) is a cytokine that downregulates pro-inflammatory responses and has a modulatory effect on hepatic fibrogenesis. The aim of this study was to investigate whether electroporative IL-10 gene therapy has a hepatic fibrolytic effect on mice.

METHODS

Hepatic fibrosis was induced by administering carbon tetrachloride (CCl4) for 10 weeks in mice. The human IL-10 expression plasmid was delivered via electroporation after hepatic fibrosis was established. Histopathology, reverse transcription polymerase chain reaction (RT-PCR), immunoblotting, and gelatin zymography were used to investigate the possible mechanisms of action of IL-10.

RESULTS

Human IL-10 gene therapy reversed CCl4-induced liver fibrosis in mice. RT-PCR revealed that IL-10 gene therapy attenuated liver TGF-beta1, collagen alpha1, fibronectin, and cell adhesion molecule mRNA upregulation. Following gene transfer, both the activation of alpha-smooth muscle actin and cyclooxygenase-2 were significantly attenuated. Furthermore, IL-10 significantly inhibited matrix metalloproteinase-2 (MMP-2) and tissue inhibitors of matrix metalloproteinase (TIMP) activation after CCl4 intoxication.

CONCLUSIONS

We demonstrated that IL-10 gene therapy attenuated CCl4-induced liver fibrosis in mice. IL-10 prevented upregulated fibrogenic and pro-inflammatory gene responses. Its collagenolytic effect may be attributed to MMP and TIMP modulation. IL-10 gene therapy may be an effective therapeutic modality against liver fibrosis with potential clinical use.

Therapeutic effect of interleukin-10 on CCl4-induced hepatic fibrosis in rats

AIM: To study the therapeutic effect of exogenous interleukin-10 on CCl₄-induced hepatic fibrosis in rats and its possible mechanisms.

METHODS: Fourty-seven SD rats were randomly divided into control group (group N) and CCl₄-induced hepatic fibrosis model group (group C). After CCl₄ was given for 9 wk, the model group was divided into three groups. Rats in group M were put to death immediately, rats in group T were treated with IL-10 for another three wk and then put to death, rats in group R recovered after three weeks and were then killed. The degree of hepatic fibrosis was measured by HE staining and histological activity index (HAI). Histological activity index (HAI), change of collagen types I and III were measured by Picrosirius staining. The expression of TNF-α, MMP-2 and TIMP-1 in liver tissue was measured by S-P immunohistochemistry.

RESULTS: CCl₄- induced experimental rat hepatic fibrosis model was established successfully. The degree of hepatic fibrosis was markedly lower in group T than in groups M and R, and there was no difference between the two groups. The expression of collagen types I and III was significantly suppressed in group T and was slightly suppressed in groups M and R. The positive levels of TNF-α, MMP-2 and TIMP-1 in group M increased significantly compared to those in group N (P < 0.01). The positive signals decreased significantly in groups T and R (P < 0.01), but positive score was significantly lower in group T than in group R (P < 0.01).

CONCLUSION: Exogenous IL-10 can reverse CCl₄-induced hepatic fibrosis in rats. IL-10 may exert its reversible effects on hepatic fibrosis by blocking CCl₄-induced inflammation, inhibiting expression of MMP-2 and TIMP-1 and promoting resolution of collagen types I and III.

Molecular pathogenesis of alcohol-induced hepatic fibrosis

Alcohol abuse is a main cause of liver fibrosis and cirrhosis in the western world. Although the major mechanisms of fibrogenesis are independent of the origin of liver injury, alcoholic liver fibrosis features distinctive characteristics, including the pronounced inflammatory response of immune cells due to elevated gut-derived endotoxin plasma levels, increased formation of reactive oxygen species (ROS), ethanol-induced pericentral hepatic hypoxia or formation of cell-toxic and pro-fibrogenic ethanol metabolites (e.g., acetaldehyde or lipid oxidation products). These factors are together responsible for increased hepatocellular cell death and activation of hepatic stellate cells (HSCs), the key cell type of liver fibrogenesis. To date, removing the causative agent is the most effective intervention to prevent the manifestation of liver cirrhosis. A novel experimental approach in fibrosis therapy is the selective induction of cell death in HSCs. Substances such as gliotoxin, anandamide or antibody against tissue inhibitor of metalloproteinase (TIMP)-1 can selectively induce cell death in activated HSCs. These new results in basic science are encouraging for the search of new antifibrotic treatment.

Interleukin-10 gene therapy reverses thioacetamide-induced liver fibrosis in mice

Hepatic fibrosis represents a process of healing and scarring in response to chronic liver injury. Interleukin-10 (IL-10) is a cytokine that downregulates the proinflammatory response and has a modulatory effect on hepatic fibrogenesis. The aim of this study was to investigate whether IL-10 gene therapy possesses anti-hepatic fibrogenesis in mice. Liver fibrosis was induced by long-term thioacetamide administration in mice. Human IL-10 expression plasmid was delivered via electroporation after liver fibrosis established. IL-10 gene therapy reversed hepatic fibrosis and prevented cell apoptosis in a thioacetamide-treated liver. RT-PCR revealed IL-10 gene therapy to reduce liver transforming growth factor-beta1, tumor necrosis factor-alpha, collagen alpha1, cell adhesion molecule, and tissue inhibitors of metalloproteinase mRNA upregulation. Following gene transfer, the activation of alpha-smooth muscle actin and cyclooxygenase-2 was significantly attenuated. In brief, IL-10 gene therapy might be an effective therapeutic reagent for liver fibrosis with potential future clinical applications.

Effect of Astragalus complanatus flavonoid on anti-liver fibrosis in rats

AIM: To observe the anti-liver fibrosis effect of Astragalus complanatus flavonoids (ACF) in rats.

METHODS: The liver fibrosis model in rats was established by injecting interperitoneally 0.2 mL/100 g 0.5% dimethylnitrosamine, thrice a week. Meanwhile, the rats were administered ACF (30, 60, 120 mg/kg) or colchicine (0.1 mg/kg) once a day for 1 mo. Serum N-propeptide of type I procollagen (PINP) and type III procollagen (PIIINP) was measured using ELISA. Malondialdehyde (MDA) and superoxide dismutase (SOD) in hepatic tissue were evaluated. Matrix metal protease-1 (MMP-1) mRNA expression was assayed by RT-PCR and the protein expression of tissue inhibitor of metal protease-1 (TIMP-1) was analyzed by immunohistochemistry.

RESULTS: In the ACF groups, SOD activity increased and MDA content decreased in comparison to the liver fibrosis model group. The serum PINP and PIIINP contents in ACF-2 and -3 group decreased compared to those in model group. In ACF-2 and -3 group, the expression of MMP-1 mRNA increased significantly and the protein expression of TIMP-1 decreased compared to that in model group.

CONCLUSION: The antifibrotic mechanisms of ACF are associated with its influence on lipid peroxidation and collagen synthesis and degradation.

Usefulness of granular BCAA after hepatectomy for liver cancer complicated with liver cirrhosis

OBJECTIVE

Nutritional disturbances such as ascites and hypoalbuminemia frequently arise after hepatectomy for liver cancer with liver cirrhosis. We examined the possibility of maintaining a favorable state of nutrition by outpatient administration of branched-chain amino acid (BCAA) granules.

METHODS

Forty-three patients who had gross liver cirrhosis complicated by liver cancer and underwent surgery up to May 2002 were given BCAA granules (n = 21, BCAA group) or no granules (n = 22, control group).

RESULTS

1) Background details such as age, sex, surgical technique, blood loss, and duration of surgery showed no significant differences. 2) Among objective findings, improvement of ascites and edema tended to occur sooner in the BCAA group, but without a significant difference. 3) Although serum albumin recovered its preoperative value 9 mo after surgery in the control group, only 6 mo was required for recovery in the BCAA group. Total protein showed similar changes, but neither group showed any difference in changes of aspartate aminotransferase, alanine transferase, or platelets. 4) One year postoperatively, the change from the preoperative indocyanine green retention rate at 15 min after intravenous administration tended to be worse in the control group, but not significantly so. 5) In the BCAA group, hyaluronic acid and type IV collagen 7S improved significantly sooner than in the control group.

CONCLUSIONS

BCAA supplementation after hepatectomy promotes rapid improvement in protein metabolism and inhibits progression to liver cirrhosis. Administration of BCAA after hepatectomy is considered beneficial to a patient's nutritional state.

Resolution of liver fibrosis in chronic CCl4 administration in the rat after discontinuation of treatment: effect of silymarin, silibinin, colchicine and trimethylcolchicinic acid

The purpose of this work was to obtain a suitable model of fibrosis, in which spontaneous reversion was minimal, to study the ability of silymarin, silibinin, colchicine and trimethylcolchicinic acid (TMCA) to reverse it. Reversal of liver fibrosis was studied in male Wistar rats after one, two or three months of CCl(4) administration (0.4 g/kg intraperitoneally, three times per week), by discontinuation of the toxin for 2 months. Silymarin (50 mg/kg), silibinin (50 mg/kg), colchicine (10 microg/rat) and trimethylcolchicinic acid (100 microg/rat) were administered daily, by gavage, after 3 months of CCl(4) administration. Collagen content was determined by measuring hydroxyproline in liver samples; glycogen, was determined utilizing the anthrone reagent; Mallory's trichromic stains of liver sections were performed. The best scheme of treatment was obtained when CCl(4) was administered during three months (collagen increased 6 times). Discontinuation of the toxin for two months produced a significant but relative small reduction of fibrosis (collagen was still 4.5 times over control). Colchicine, TMCA, silymarin or silibinin treatment showed no significant fibrolitic effect. This scheme of treatment may be an excellent tool to study the ability of drugs to reverse fibrosis. The hepatoprotective properties of silymarin, silibinin, colchicine and trimethylcolchinic acid may be irrelevant to reverse established cirrhosis.

Expression of tissue inhibitor of matrix metalloproteinases-1 during aging in rat liver

AIM: To investigate the expression and role of tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) during natural aging in rat liver and to detect the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9.

METHODS: The rats were divided into 3-mo-old group (n = 5), 10-mo-old group (n = 5) and 24-mo-old group (n = 5). Histopathologic changes of liver were observed with HE and Masson stain. The location and protein expressions of TIMP-1 were determined by immunohistochemistry and Western blot; message RNA (mRNA) levels were measured in livers from rats of various ages by semi-quantitative reverse transcriptional polymerase chain reaction (RT-PCR). In addition, the expression of MMP-2 and MMP-9 was assessed by RT-PCR and Western blot.

RESULTS: Histologic examination showed that the aging liver had excessive fatty degeneration and collagen deposition. Immunohistochemical staining showed that TIMP-1 related antigen in livers was located in cytoplasm. The protein expression of TIMP-1 was significantly higher in the oldest animals and the mRNA expression was increased significantly in the 24-mo-old rats (t = 4.61, P = 0.002<0.05, 24-vs 10-mo-old rats; t = 4.31, P = 0.003<0.05, 24- vs 3-mo-old rats). The expression of MMP-2 and MMP-9 had no change during aging; the ratios TIMP-1/MMP-2 and TIMP-1/MMP-9 in aging liver were significantly higher than those in maturation and young livers.

CONCLUSION: TIMP-1 may play an important role in the process of liver aging.

Metallothionein gene therapy for chemical-induced liver fibrosis in mice

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

Production of pro- and anti-fibrotic agents by rat Kupffer cells; the effect of octreotide

Kupffer cells may be involved in liver fibrogenesis through production of TGF-beta1. Their role in fibrinolysis is less clear. Octreotide, a synthetic analogue of somatostatin, is often used in cirrhotic patients. Its effect on Kupffer cells was studied. Isolated rat Kupffer cells were cultured in the presence of lipopolysaccharide and/or octreotide. TGF-beta1, leptin, collagenase (MMP-1), and urokinase-type plasminogen activator (uPA) were assessed in supernatants by ELISA, and MMP-2 and MMP-9 by zymography. Kupffer cells produced large amounts of MMP-1 and lipopolysaccharide induced a significant (P < 0.02) early increase. Octreotide and lipopolysaccharide caused a synergistic effect on MMP-1 secretion. By contrast, MMP-9 production stimulated by lipopolysaccharide was suppressed by octreotide. Kupffer cells produced a basal amount of uPA, significantly increased after lipopolysaccharide or octreotide incubation (P < 0.001). Large amounts of TGF-beta1 were produced in a time-dependent manner by unstimulated Kupffer cells. Lipopolysaccharide and octreotide, alone or in combination, induced a significant inhibition of this production (P < 0.01). Kupffer cells did not produce leptin, a recently identified mediator of liver fibrosis, or MMP-2. Kupffer cells may play a significant role in liver fibrinolysis. Octreotide, acting on TGF-beta1, uPA, and MMP-1 production, may be a useful agent for fibrosis resolution.

Molecular mechanisms of alcohol-induced hepatic fibrosis

Alcohol abuse is a major cause of liver fibrosis and cirrhosis in developed countries. Before alcoholic liver fibrosis becomes evident, the liver undergoes several stages of alcoholic liver disease including steatosis and steatohepatitis. Although the main mechanisms of fibrogenesis are independent of the etiology of liver injury, alcoholic liver fibrosis is distinctively characterized by a pronounced inflammatory response due to elevated gut-derived endotoxin plasma levels, an augmented generation of oxidative stress with pericentral hepatic hypoxia and the formation of cell-toxic and profibrogenic ethanol metabolites (e.g. acetaldehyde or lipid oxidation products). These factors, based on a complex network of cytokine actions, together result in increased hepatocellular damage and activation of hepatic stellate cells, the key cell type of liver fibrogenesis. Although to date removal of the causative agent, i.e. alcohol, still represents the most effective intervention to prevent the manifestation of alcoholic liver disease, sophisticated molecular approaches are underway, aiming to specifically blunt profibrogenic signaling pathways in liver cells or specifically induce cell death in activated hepatic stellate cells to decrease the scarring of the liver.

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Effect of interleukin-10 and platelet-derived growth factor on expressions of matrix metalloproteinases-2 and tissue inhibitor of metalloproteinases-1 in rat fibrotic liver and cultured hepatic stellate cells

AIM

To examine the expressions of matrix metalloproteinases-2 (MMP-2) and tissue inhibitor of metalloproteinases-1 (TIMP-1) in rat fibrotic liver and in normal rat hepatic stellate cells, and to investigate the changes in their expressions in response to treatment with interleukin-10 (IL-10) and platelet-derived growth factor (PDGF).

METHODS

Rat models of CCl4-induced hepatic fibrosis were established and the liver tissues were sampled from the rats with or without IL-10 treatment, and also from the control rats. The expressions of MMP-2 and TIMP-1 in liver tissues were detected by S-P immunohistochemistry, and their expression intensities were evaluated in different groups. Hepatic stellate cells (HSCs) were isolated from normal rat and cultured in vitro prior to exposure to PDGF treatment or co-treatment with IL-10 and PDGF. MMP-2 and TIMP-1 levels were measured by semi-quantitative reverse transcriptional polymerase chain reaction (RT-PCR).

RESULTS

CCl4- induced rat hepatic fibrosis models were successfully established. The positive expressions of MMP-2 and TIMP-1 increased obviously with the development of hepatic fibrosis, especially in untreated model group (84.0% and 92.0%, P<0.01). The positive signals decreased significantly following IL-10 treatment (39.3% and 71.4%, P<0.01 and P<0.05) in a time-dependent manner. TIMP-1 mRNA in PDGF-treated group was significantly increased time-dependently in comparison with that of the control group, but PDGF did not obviously affect MMP-2 expression. No difference was noted in TIMP-1 and MMP-2 expressions in HSCs after IL-10 and PDGF treatment (P>0.05).

CONCLUSION

MMP-2 and TIMP-1 expressions increase in liver tissues with the development of fibrosis, which can be inhibited by exogenous IL-10 inhibitor. PDGF induces the up-regulation of TIMP-1 but not MMP-2 in the HSCs. IL-10 inhibits TIMP-1 and MMP-2 expressions in HSCs induced by PDGF.

Pathological comparison of hepatic-fibrosis models induced by porcine serum and carbon tetrachloride in rats

AIM: To compare liver pathological changes between two different hepatic-fibrosis models induced by porcine serum and carbon tetrachloride in rats.

METHODS: Hepatic fibrosis was induced in rats by biweekly intraperitoneal injection of porcine serum (0.5 mL) or 400 mL/L carbon tetrachloride (2 mL/kg) for 7 weeks. Five rats were randomly selected from the survivals in each group. Liver tissue was removed, fixed, sliced and stained with hematoxylin and esosin for routine light-microscopy, Masson trichrome for collagen, Jame's double ammoniated siver solution for reticulin, and then subjected to semiquantitative evaluation by pathological image analyzer. Another portion of liver tissue was prepared for electron microscopy.

RESULTS: Liver tissue in rats receiving pig serum displayed narrow fibrotic sepatae including obvious collagen deposition and more mesenchymal constituents, and collagen was confined to the septae. Hepatocellular injury is rare. In contrast, in the livers from rats treated with CCl₄, the fibrotic septae were coarse, more cellular and diffuse. The parenchymal damage was more severe and extensive. The fatty metamorphosis of hepatocytes was evident. Semiquantitative analyses suggested that quantity of collagenic fibers and reticular fibers in CCl₄ group were significantly higher than those in porcine serum group.

CONCLUSION: Hepatic fibrosis in rats induced by CCl₄ is more severe than that induced by porcine serum.

Inhibitory effect of Huangqi Zhechong decoction on liver fibrosis in rat

AIM: To assess the inhibitory effect of Huangqi Zhechong decoction on hepatic fibrosis in rats induced by CCl₄ plus alcohol and high fat low protein diet.

METHODS: Male SD rats were randomly divided into hepatic fibrosis model group, control group and 3 treatment groups consisting of 12 rats in each group. Except for the normal control group, all the rats were subcutaneously injected with CCl₄ at a dosage of 3 mL/kg. In 3 treated groups, either high-dose group (9 mL/kg), or medium-dose group (6 mL/kg), or low-dose group (3 mL/kg) was daily gavaged with Huangqi Zhechong decoction, and saline vehicle was given to model and normal control rats. Enzyme-linked immunosorbent assay (ELISA) and biochemical examinations were used to determine the changes of alanine aminotransferase (ALT), aspartate aminotransferase (AST), hyaluronic acid (HA), laminin (LN), type-III-procollagen-N- peptide (PIIIP), and type IV collagen content in serum, and hydroxyproline (Hyp) content in liver after sacrificing the rats. Pathologic changes, particularly fibrosis were examined by hematoxylin and eosin (HE) and Van Gieson staining.

RESULTS: Compared with the model control group, serum ALT, AST, HA, LN, PIIIP and type IV collagen levels dropped markedly in Huangqi Zhechong decoction groups, especially in the medium-dose Huangqi Zhechong decoction group (1 954 ± 576 U/L vs 759 ± 380 U/L, 2 735 ± 786 U/L vs 1 259 ± 829 U/L, 42.74 ± 7.04 ng/mL vs 20.68 ± 5.85 ng/mL, 31.62 ± 5.84 ng/mL vs 14.87 ± 1.45 ng/mL, 3.26 ± 0.69 ng/mL vs 1.47 ± 0.46 ng/mL, 77.68 ± 20.23 ng/mL vs 25.64 ± 4.68 ng/mL, respectively) (P < 0.05). The Hyp content in liver tissue was also markedly decreased (26.47 ± 11.24 mg/mgprot vs 9.89 ± 3.74 mg/mgprot) (P < 0.01). Moreover, the stage of the rat liver fibrosis in Huangqi Zhechong decoction groups was lower than that in model group, and more dramatic drop was observed in medium-dose Huangqi Zhechong decoction group (P < 0.01).

CONCLUSION: Huangqi Zhechong decoction can inhibit hepatic fibrosis resulted from chronic liver injure, retard the development of cirrhosis, and notably ameliorate the liver function. It may be a safe and effective therapeutic drug for patients with fibrosis.

The antioxidant and antifibrogenic effects of the glycosaminoglycans hyaluronic acid and chondroitin-4-sulphate in a subchronic rat model of carbon tetrachloride-induced liver fibrogenesis

Hepatic fibrosis involves the interplay of many factors including reactive oxygen species. Recent reports described antioxidant properties of glycosaminoglycans (GAGs). Since several findings have shown that hyaluronic acid (HYA) and chondroitin-4-sulphate (C4S) may act as antioxidant molecules, the aim of this research was to evaluate the antioxidant effects of HYA and C4S treatment in a rat model of liver fibrosis. The effect on tissue inhibitors of metalloproteinases (TIMPs) was also studied. Liver fibrosis was induced in rats by eight intraperitoneal injections of CCl4, twice a week for 6 weeks. HYA or C4S alone (25 mg/kg) or HYA and C4S in combination (12.5 + 12.5 mg/kg) were administered daily by the same route during the 6 weeks. At the end of the 6-week treatment period (24 h after the last dose of GAGs), the following parameters were evaluated: (1) serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, as index of hepatic cell disruption; (2) hepatic conjugated dienes (CD), as index of lipid peroxidation; (3) hepatic TIMPs activity and expression; (4) hepatic superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity, as index of endogenous defences; (5) hepatic hydroxyproline, as index of collagen deposition. CCl4-induced liver fibrosis enhanced lipid peroxidation and TIMPs activation, increased ALT and AST, depleted antioxidants SOD and GPx, and caused collagen deposition in liver tissue. Treatment with GAGs, especially when in combination, successfully reduced ALT and AST rise, lipid peroxidation by evaluating conjugated dienes, TIMPs activation and mRNA expression, partially restored SOD and GPx activities, and limited collagen deposition in the hepatic tissue. The data obtained showed that these molecules were able to limit hepatic injury induced by chronic CCl4 intoxication and especially limited liver fibrosis. They also confirm that HYA and C4S may exert antioxidant mechanism, while reduction of TIMPs expression suggests that GAGs may influence MMPs and TIMPs imbalance in liver fibrosis.

Ginkgo biloba extract reverses CCl4–induced liver fibrosis in rats

AIM: To study the reversing effect of Ginkgo biloba extract (GbE) on established liver fibrosis in rats.

METHODS: Following confirmation of CCl₄-induced liver fibrosis, GbE or saline was administrated to the rats for 4 weeks. The remaining rats received neither CCl₄ nor GbE as normal control. The four groups were compared in terms of serum enzymes, tissue damage, expression of αSMA and tissue inhibitor-1 of metalloproteinase (TIMP-1) and metalloproteinase-1 (MMP-1).

RESULTS: Compared with saline-treated group, liver fibrosis rats treated with GbE had decreased serum total bilirubin (P < 0.01) and aminotransferase levels (P < 0.01) and increased levels of serum albumin (P < 0.01). Microscopic studies revealed that the livers of rats receiving GbE showed allieviation in fibrosis (P < 0.05) as well as expression of αSMA (P<0.01). The liver collagen and reticulum contents were lower in rats treated with GbE than saline-treated group (P < 0.01). RT-PCR revealed that the level of TIMP-1 decreased while the level of MMP-1 increased in GbE group.

CONCLUSION: Administration of GbE improved CCl₄–induced liver fibrosis. It is possibly attributed to its effect of inhibiting the expression of TIMP-1 and promoting the apoptosis of hepatic stellate cells.

Gene expression profiling of alcoholic liver disease in the baboon (Papio hamadryas) and human liver

The molecular pathogenesis of alcoholic liver disease (ALD) is not well understood. Gene expression profiling has the potential to identify new pathways and altered molecules in ALD. Gene expression profiles of ALD in a baboon model and humans were compared using DNA arrays. Reverse transcriptase-polymerase chain reaction and immunohistochemistry were used for downstream analysis of array results. cDNA array analysis revealed differential expression of several novel genes and pathways in addition to genes known to be involved in ALD pathogenesis. Overall gene expression profiles were similar in both species, with a majority of genes involved with fibrogenesis and xenobiotic metabolism, as well as inflammation, oxidant stress, and cell signaling. Genes associated with stellate cell activation (collagens, matrix metalloproteinases, tissue inhibitors of matrix metalloproteinase) were up-regulated in humans. Decreased expression of several metallothioneins was unexpected. Fourteen molecules related to the annexin family were up-regulated, including annexin A1 and A2. Immunofluorescence revealed a marked overexpression of annexin A2 in proliferating bile duct cells, hepatocyte cell surface, and selective co-localization with CD14-positive cells in human ALD. The gene expression profile of ALD is dominated by alcohol metabolism and inflammation and differs from other liver diseases. Annexins may play a role in the progression of fibrosis in ALD.

Novel inhibitors of procollagen C-proteinase. Part 2: glutamic acid hydroxamates

Glutamic acid derived hydroxamates were identified as potent and selective inhibitors of procollagen C-proteinase, an essential enzyme for the processing of procollagens to fibrillar collagens. Such compounds have potential therapeutic application in the treatment of fibrosis.

Effect of Chinese herb Shuangjiawuling on expression of TIMPs in rat with liver fibrosis

AIM: To explore the effect of Chinese herb Shuangjiawuling in preventing hepatic fibrosis in rat with liver fibrosis.

METHODS: Rat immunogenic liver fibrosis model was induced by administration human serum albumin (HSA 200 g/L) intravenously, 80 rats were randomly divided into 5 groups. Shuangjiawuling was taken orally simultaneously with (group A), immediately after (group B), or 3 months after (group C) administration of HAS intravenously. Colchine tablets were taken orally with the administration of HAS (group D), normal rats were used as control (Group E). The pathological changes of liver tissue were observed by HE and Von-Gieson staining. The hepatic mRNA and protein of TIMP-1 and TIMP-2 were analyzed by in site hybridization and immunohistochemistry.

RESULTS: Hepatic fibrosis developed gradually and became obviously on the third month after administration of HAS. And strong expressions of TIMP-1 and TIMP-2 were observed, however, its expression and hepatic fibrosis were reduced dramatically following administration of Shuangjiawuling and colchine tablets. The effect of Shuangjiawuling in preventing fibrosis was superior to that of colchine tablets (P<0.05), and its effect in group A, B, and C decreased in order.

CONCLUSION: Chinese herb Shuangjiawuling can inhibit the development of hepatic fibrosis and the expression of TIMPs, and promoted the effect of the degradation of the extracellular matrix.