Tissue inhibitor of metalloproteinases-1 promotes liver fibrosis development in a transgenic mouse model

TIMP-1 is upregulated, but not essential in hepatic fibrogenesis and carcinogenesis in mice

Tissue inhibitor of metalloproteinases-1 (TIMP-1) is upregulated during hepatic fibrogenesis and considered to promote fibrosis in the injured liver by inhibition of matrix metalloproteases (MMP) and degradation of extracellular matrix. Moreover, TIMP-1 displays anti-apoptotic properties, in patients with hepatocellular carcinoma (HCC) TIMP-1 serum levels are elevated and high TIMP-1 expression levels in HCC are associated with a poor prognosis. Therefore, TIMP-1 could functionally link fibrogenesis and carcinogenesis in the liver. The aim of our study was to characterize the role of TIMP-1 in hepatic fibrogenesis and carcinogenesis. Experimental hepatic fibrogenesis as well as diethylnitrosamine (DEN) -induced hepatocarcinogenesis were studied in TIMP-1-deficient mice and wild type littermates. Hepatic TIMP-1 expression was upregulated following induction of liver fibrosis by bile duct ligation (BDL) or by carbon tetrachloride (CCl₄). Unexpectedly, in comparison to wild type littermates, TIMP-1-deficient mice were not protected from liver fibrosis induced by BDL or CCl₄. TIMP-1 expression was significantly higher in HCC nodules than in surrounding liver tissue. However, experimental hepatic carcinogenesis was similar in TIMP-1-deficient mice and wild type littermates following DEN-treatment or combined treatment with DEN and CCl₄. Therefore we concluded that TIMP-1 is not essential for hepatic fibrogenesis and carcinogenesis in mice.

Epidermal growth factor signaling protects from cholestatic liver injury and fibrosis

We have demonstrated that the signal transducer and activator of transcription 3 (STAT3) protects from cholestatic liver injury. Specific ablation of STAT3 in hepatocytes and cholangiocytes (STAT3∆hc) aggravated liver damage and fibrosis in the Mdr2-/- (multidrug resistance 2) mouse model for cholestatic disease. Upregulation of bile acid biosynthesis genes and downregulation of epidermal growth factor receptor (EGFR) expression were observed in STAT3∆hc Mdr2-/- mice but the functional consequences of these processes in cholestatic liver injury remained unclear. Here, we show normal canalicular architecture and bile flow but increased amounts of bile acids in the bile of STAT3∆hc Mdr2-/- mice. Moreover, STAT3-deficient hepatocytes displayed increased sensitivity to bile acid-induced apoptosis in vitro. Since EGFR signaling has been reported to protect hepatocytes from bile acid-induced apoptosis, we generated mice with hepatocyte/cholangiocyte-specific ablation of EGFR (EGFR∆hc) and crossed them to Mdr2-/- mice. Importantly, deletion of EGFR phenocopied deletion of STAT3 and led to aggravated liver damage, liver fibrosis, and hyperproliferation of K19+ cholangiocytes. Our data demonstrate hepatoprotective functions of the STAT3-EGFR signaling axis in cholestatic liver disease.

KEY MESSAGE

STAT3 is a negative regulator of bile acid biosynthesis. STAT3 protects from bile acid-induced apoptosis and regulates EGFR expression. EGFR signaling protects from cholestatic liver injury and fibrosis.

Dose-Dependent Metabolic Reprogramming and Differential Gene Expression in TCDD-Elicited Hepatic Fibrosis

We have previously shown that in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-elicited NAFLD progression, central carbon, glutaminolysis, and serine/folate metabolism are reprogrammed to support NADPH production and ROS defenses. To further investigate underlying dose-dependent responses associated with TCDD-induced fibrosis, female C57BL/6 mice were gavaged with TCDD every 4 days (d) for 28 d or 92 d. RNA-Seq, ChIP-Seq (2 h), and 28 d metabolomic (urine, serum, and hepatic extract) analyses were conducted with complementary serum marker assessments at 92 d. Additional vehicle and 30 µg/kg treatment groups were allowed to recover for 36 d following the 92-d treatment regimen to examine recovery from TCDD-elicited fibrosis. Histopathology revealed dose-dependent increases in hepatic fat accumulation, inflammation, and periportal collagen deposition at 92 days, with increased fibrotic severity in the recovery group. Serum proinflammatory and profibrotic interleukins-1β, -2, -4, -6, and -10, as well as TNF-α and IFN-γ, exhibited dose-dependent induction. An increase in glucose tolerance was observed with a concomitant 3.0-fold decrease in hepatic glycogen linked to increased ascorbic acid biosynthesis and proline metabolism, consistent with increased fibrosis. RNA-Seq identified differential expression of numerous matrisome genes including an 8.8-fold increase in Tgfb2 indicating myofibroblast activation. Further analysis suggests reprogramming of glycogen, ascorbic acid, and amino acid metabolism in support of collagen deposition and the use of proline as a substrate for ATP production via the proline cycle. In summary, we demonstrate that glycogen, ascorbic acid, and amino acid metabolism are also reorganized to support remodeling of the extracellular matrix, progressing to hepatic fibrosis in response to chronic injury from TCDD.

Involvement of matrix metalloproteinases (MMPs) and inflammasome pathway in molecular mechanisms of fibrosis

Fibrosis is a basic connective tissue lesion defined by the increase in the fibrillar extracellular matrix (ECM) components in tissue or organ. Matrix metalloproteinases (MMPs) are a major group of proteases known to regulate the turn-over of ECM and so they are suggested to be important in tissue remodelling observed during fibrogenic process associated with chronic inflammation. Tissue remodelling is the result of an imbalance in the equilibrium of the normal processes of synthesis and degradation of ECM components markedly controlled by the MMPs/TIMP imbalance. We previously showed an association of the differences in collagen deposition in the lungs of bleomycin-treated mice with a reduced molar pro-MMP-9/TIMP-1 ratio. Using the carbon tetrachloride (CCl₄) preclinical model of liver fibrosis in mice, we observed a significant increase in collagen deposition with increased expression and release of tissue inhibitors of metalloproteinase (TIMP)-1 both at 24 h and 3 weeks later. This suggests an early altered regulation of matrix turnover involved in the development of fibrosis. We also demonstrated an activation of NLRP3-inflammasome pathway associated with the IL-1R/MyD88 signalling in the development of experimental fibrosis both in lung and liver. This was also associated with an increased expression of purinergic receptors mainly P2X₇. Finally, these observations emphasize those effective therapies for these disorders must be given early in the natural history of the disease, prior to the development of tissue remodelling and fibrosis.

Aldosterone Induces Tissue Inhibitor of Metalloproteinases-1 Expression and Further Contributes to Collagen Accumulation

Aldosterone induces myocardial fibrosis. Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a key factor of myocardial fibrosis. This study tested the hypothesis that aldosterone induces TIMP-1 expression and contributes to the fibrotic process. We prospectively enrolled 54 patients with primary aldosteronism, and measured plasma TIMP-1 and echocardiographic parameters. In the cell study, we investigated the possible molecular mechanism by which aldosterone induces TIMP-1 secretion and the effects on collagen accumulation. In the animal study, we measured serum TIMP-1 levels, cardiac TIMP-1 levels, and cardiac structure in an aldosterone infusion mouse model using implantation of aldosterone pellets. In patients with primary aldosteronism, plasma TIMP-1 was correlated with 24-hour urinary aldosterone, left ventricular mass, and impairment of left ventricular diastolic function. In human cardiac fibroblasts, TIMP-1 protein and mRNA expressions were significantly increased by aldosterone through the glucocorticoid receptor/PI3K/Akt/nuclear factor-κB pathway. TIMP-1 small-interfering RNA significantly reduced aldosterone-induced collagen accumulation, and aldosterone did not alter the levels of collagen1a1 or matrix metalloproteinase-1 mRNA. The aldosterone-induced TIMP-1 expression was inversely related to matrix metalloproteinase-1 activity. Furthermore, in the animal model, the serum and cardiac levels of TIMP-1 were significantly elevated in the mice that received aldosterone infusion. This elevation was blocked by RU-486 but not by eplerenone, suggesting that the effect was through glucocorticoid receptors. In a long-term aldosterone infusion model, serum TIMP-1 was associated with serum aldosterone level, cardiac structure, and fibrosis. In conclusion, aldosterone induced TIMP-1 expression in vivo and in vitro. This increased TIMP-1 expression resulted in enhanced collagen accumulation via the suppression of matrix metalloproteinase-1 activity.

SP1 and UTE1 Decoy ODNs inhibit activation and proliferation of hepatic stellate cells by targeting tissue inhibitors of metalloproteinase 1

Background

The excessive accumulation of extracellular matrix of hepatic fibrosis is positively correlated with tissue inhibitors of metalloproteinase 1 (TIMP1). Here we aimed to investigate whether TIMP1 may be down-regulated by Decoy ODNs strategy to capture transcriptional factor upstream TIMP1 element 1 (UTE1) and specificity protein 1(SP1).

Results

By luciferase reporter assays, we confirmed that these Decoy ODNs could influence the promoter activation of TIMP-1, α-SMA and Collagen Iα2 (COLΙα2) genes as well as the enhancer activation of TRE in HSC-T6 cells, and the combination tended to be more effective than SP1 or UTE1 Decoy ODN alone. Western blot analysis also demonstrated down-regulation of the expression of those target genes except for TGF-β. Furthermore, we observed that the viability of HSC-T6 cells at 72 h was significantly in decline in combination group.

Conclusion

The combination of SP1 and UTE1 Decoy ODNs treatments inhibit the activation and proliferation of HSCs more effectively than one of the Decoy ODNs through co-regulation of TIMP1 and TGF-β signal pathway but not the expression of TGF-β itself.

Plasma ADAMTS-13 protein is not associated with portal hypertension or hemodynamic changes in patients with cirrhosis

BACKGROUND

Activated hepatic stellate cells synthesize the matrix metalloprotease ADAMTS13, which may be involved in the development of liver cirrhosis and portal hypertension. Plasma ADAMTS13 activity has been reported as both increased and decreased in cirrhosis, but ADAMTS13 protein has not previously been examined.

AIM

To evaluate ADAMTS13 protein in the hepatic circulation and the relation to disease severity, portal pressure, and systemic hemodynamics in cirrhotic patients.

METHODS

Sixty-one cirrhotic patients (Child class: A=22; B=21; C=18) and nine healthy controls underwent a liver vein catheterization with measurement of splanchnic and systemic hemodynamics, and plasma ADAMTS13 protein concentration in a hepatic vein and the femoral artery.

RESULTS

ADAMTS13 protein concentrations were increased in cirrhotic patients compared with controls (774ng/ml [IQR: 585-955] vs. 538ng/ml [IQR: 484-631], p<0.03). There were no significant correlations to MELD score, Child Pugh score, portal pressure, nor systemic vascular resistance or cardiac output.

CONCLUSIONS

The increased concentration of ADAMTS13 protein in the hepatic circulation may reflect an increased number of active hepatic stellate cells in cirrhosis. However, ADAMTS13 was unrelated to portal hypertension and systemic hemodynamics. In conclusion, ADAMTS13 does not appear to be associated to disease severity or the hemodynamic derangement in patients with cirrhosis.

Versican: a novel modulator of hepatic fibrosis

Little is known about the deposition and turnover of proteoglycans in liver fibrosis, despite their abundance in the extracellular matrix. Versican plays diverse roles in modulating cell behavior in other fibroproliferative diseases, but remains poorly described in the liver. Hepatic fibrosis was induced by carbon tetrachloride treatment of C57BL/6 mice over 4 weeks followed by recovery over a 28-day period. Primary mouse hepatic stellate cells (HSCs) were activated in culture and versican was transiently knocked down in human (LX2) and mouse HSCs. Expression of versican, A Disintegrin-like and Metalloproteinase with Thrombospondin-1 motifs (ADAMTS)-1, -4, -5, -8, -9, -15, and -20, and markers of fibrogenesis were studied using immunohistochemistry, real-time quantitative PCR, and western blotting. Immunohistochemistry showed increased expression of versican in cirrhotic human livers and the mouse model of fibrosis. Carbon tetrachloride treatment led to significant increases in versican expression and the proteoglycanases ADAMTS-5, -9, -15, and -20, alongside TNF-α, α-smooth muscle actin (α-SMA), collagen-1, and TGF-β expression. During recovery, expression of many of these genes returned to control levels. However, expression of ADAMTS-5, -8, -9, and -15 showed delayed increases in expression at 28 days of recovery, which corresponded with decreases in versican V0 and V1 cleavage products (G1-DPEAAE(1401) and G1-DPEAAE(441)). Activation of primary HSCs in vitro significantly increased versican, α-SMA, and collagen-1 expression. Transient knockdown of versican in HSCs led to decreases in markers of fibrogenesis and reduced cell proliferation, without inducing apoptosis. Versican expression increases during HSC activation and liver fibrosis, and proteolytic processing occurs during the resolution of fibrosis. Knockdown studies in vitro suggest a possible role of versican in modulating hepatic fibrogenesis.

Resveratrol mediates therapeutic hepatic effects in acquired and genetic murine models of iron-overload

BACKGROUND & AIMS

Abnormal iron metabolism and hepatic iron-overload is a major cause of liver injury and in the development of chronic liver diseases. Iron-overload-mediated liver disease leads to end-stage cirrhosis and/or hepatocellular carcinoma.

METHODS

Using a genetic hemochromatosis (hemojuvelin knockout mice) and non-genetic (secondary iron-overload) murine models of hepatic iron-overload, we elucidated the mechanism of hepatic iron injury and the therapeutic effects of resveratrol.

RESULTS

Hepatic iron-overload was associated with hepatosplenomegaly, increased oxidative stress, hepatic fibrosis, and inflammation, and a pro-apoptotic state which was markedly corrected by resveratrol therapy. Importantly our aging studies with the hemojuvelin knockout mice showed advanced liver disease in association with steatosis in the absence of a diabetic state which recapitulates the essential pathological features seen in clinical iron-overload. Chronic hepatic iron-overload showed increased nuclear localization of acetylated Forkhead fox-O-1 (FoxO1) transcription factor whereas resveratrol dietary intervention reversed the acetylation of FoxO1 in association with increased SIRT1 levels which together with its pleotropic antioxidant properties are likely key mechanisms of its therapeutic action. Importantly, resveratrol treatment did not affect the degree of hepatic iron-overload but rather direct protects the liver from iron-mediated injury.

CONCLUSIONS

Our findings illustrate a novel and definitive therapeutic action of resveratrol and represent an economically feasible therapeutic intervention to treat hepatic iron-overload and liver disease.

Lung Infection by Human Bocavirus Induces the Release of Profibrotic Mediator Cytokines In Vivo and In Vitro

Human Bocavirus subtype 1 (HBoV1) is associated with respiratory diseases and may contribute to chronic lung diseases by persisting in the infected host. Here the question was addressed if HBoV infections could contribute to fibrogenesis processes as suggested by previously published clinical observations. Cytokine profiles induced by HBoV infection in CuFi-8 air-liquid interphase cell cultures and in bronchoalveolar lavage fluid (BALF) of 20 HBoV-positive and 12 HBoV-negative patients were analysed by semi-quantitative Western spot blot analyses. Although lots of cytokines were regulated independently of HBoV status, several cytokines associated with lung fibrosis and tumour development, e.g., EGF, VEGF, TARC (CCL17), TNF-α, TNF-β, TIMP-1, were clearly upregulated in the HBoV-positive cohort. These findings suggest that the development of lung fibrosis might be triggered by HBoV induced cytokine expression.

Role of fibrogenic and inflammatory cytokines in HCV-induced fibrosis

HCV is one of the main causative agents of liver fibrosis and hepatocellular carcinoma. Liver inflammation resulting from HCV infection triggers fibrosis. In HCV-related fibrosis, differentiated hepatic stellate cells (HSCs) known as myofibroblasts participate in the fibrogenic and inflammatory response. TGF-β1 and CTGF, released from these HSCs, have been implicated as master cytokines mediating HCV induced hepatic fibrosis. PDGF is another potent mitogen, which facilitates the progression of liver fibrosis by enhancing the proliferation and migration of HSCs. In addition to these major cytokines, the release of TNF-α, IL-6, IL-1b and IL-10 by immune cells also promotes the effect of HCV induced fibrosis. Targeting these cytokines may offer the potential for treatments to prevent or cure fibrosis.

Ethyl acetate fraction of Amomum xanthioides improves bile duct ligation-induced liver fibrosis of rat model via modulation of pro-fibrogenic cytokines

We investigated anti-hepatofibrotic effects of ethyl acetate fraction of Ammomum xanthoides (EFAX) using bile duct ligation (BDL)-induced hepatic fibrosis in a rat model. Male SD rats (6 weeks old) underwent BDL followed by 15 days of orall administration of EFAX (12.5, 25 or 50 mg/kg) or ursodeoxycholic acid (25 mg/kg). BDL caused animal death, ascites formation, alterations in serum biochemistries, and severe hepatic injury with excessive collagen deposition, whereas EFAX treatment significantly attenuated these effects. BDL markedly increased the pro-fibrogenic cytokines (TGF-β, PDGF-β, and CTGF) and the extracellular matrix indicators α-SMA, TIMP-1 and collagen type 1 in hepatic proteins and gene expression levels, which were notably normalized by EFAX treatment. EFAX also markedly normalized pro-fibrogenic signaling molecules including Smad2/3, Smad7, Akt, p44/42, and p38. We further explored EFAX mechanisms of actions using LX-2 cells (human derived hepatic stellate cell line). Pre-treatment with EFAX drastically attenuated the activation of α-SMA and Smad2/3, which are downstream molecules of TGF-β. These findings suggest that EFAX may be a potent anti-hepatofibrotic agent, and its corresponding mechanisms primarily involve the modulation of pro-fibrogenic cytokines.

M1 Muscarinic Receptor Deficiency Attenuates Azoxymethane-Induced Chronic Liver Injury in Mice

Cholinergic nervous system regulates liver injury. However, the role of M1 muscarinic receptors (M1R) in modulating chronic liver injury is uncertain. To address this gap in knowledge we treated M1R-deficient and WT mice with azoxymethane (AOM) for six weeks and assessed liver injury responses 14 weeks after the last dose of AOM. Compared to AOM-treated WT mice, M1R-deficient mice had attenuated liver nodularity, fibrosis and ductular proliferation, α-SMA staining, and expression of α1 collagen, Tgfβ-R, Pdgf-R, Mmp-2, Timp-1 and Timp-2. In hepatocytes, these findings were associated with reductions of cleaved caspase-3 staining and Tnf-α expression. In response to AOM treatment, M1R-deficient mice mounted a vigorous anti-oxidant response by upregulating Gclc and Nqo1 expression, and attenuating peroxynitrite generation. M1R-deficient mouse livers had increased expression of Trail-R2, a promotor of stellate cell apoptosis; dual staining for TUNNEL and α-SMA revealed increased stellate cells apoptosis in livers from M1R-deficient mice compared to those from WT. Finally, pharmacological inhibition of M1R reduced H₂O₂-induced hepatocyte apoptosis in vitro. These results indicate that following liver injury, anti-oxidant response in M1R-deficient mice attenuates hepatocyte apoptosis and reduces stellate cell activation, thereby diminishing fibrosis. Therefore, targeting M1R expression and activation in chronic liver injury may provide therapeutic benefit.

Unravelling osteoarthritis-related synovial fibrosis: a step closer to solving joint stiffness

Synovial fibrosis is often found in OA, contributing heavily to joint pain and joint stiffness, the main symptoms of OA. At this moment the underlying mechanism of OA-related synovial fibrosis is not known and there is no cure available. In this review we discuss factors that have been reported to be involved in synovial fibrosis. The aim of the study was to gain insight into how these factors contribute to the fibrotic process and to determine the best targets for therapy in synovial fibrosis. In this regard, the following factors are discussed: TGF-β, connective tissue growth factor, procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2, tissue inhibitor of metalloproteinase 1, A disintegrin and metalloproteinase domain 12, urotensin-II, prostaglandin F2α and hyaluronan.

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

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

Human Amnion-Derived Mesenchymal Stem Cell Transplantation Ameliorates Liver Fibrosis in Rats

Mesenchymal stem cells (MSCs) are a valuable cell source in regenerative medicine. Recently, several studies have shown that MSCs can be easily isolated from human amnion. In this study, we investigated the therapeutic effect of transplantation of human amnion-derived MSCs (hAMSCs) in rats with liver fibrosis.

METHODS

Liver fibrosis was induced by an intraperitoneal injection of 2 mL/kg of 50% carbon tetrachloride twice a week for 6 weeks. At 3 weeks, hAMSCs (1 × 10(6) cells) were transplanted intravenously. Rats were sacrificed at 7 weeks, and histological analyses and quantitative reverse-transcription polymerase chain reaction were performed. In vitro experiments were conducted to investigate the effect of hAMSCs on the activation of Kupffer cells.

RESULTS

Transplantation of hAMSCs significantly reduced the fibrotic area, deposition of type-I collagen, the number of α-smooth muscle actin-positive hepatic stellate cells, and CD68-positive Kupffer cells in the livers. messenger RNA expression of α-smooth muscle actin and tissue inhibitor of metalloproteinase-1 was significantly decreased and the expression of matrix metalloproteinase-9 and hepatocyte growth factor was significantly increased in the liver of hAMSC-treated rats. Transplantation of hAMSCs at 3 weeks plus 5 weeks did not have an additive effect. In vitro experiments demonstrated that Kupffer cell activation induced by lipopolysaccharide was significantly decreased by culturing with conditioned medium obtained from hAMSCs.

CONCLUSIONS

Transplantation of hAMSCs provided significant improvement in a rat model of liver fibrosis, possibly through the inhibition of Kupffer cell and hepatic stellate cell activation. hAMSCs may be a potential new treatment for liver fibrosis.

Matrix metalloproteinases in liver injury, repair and fibrosis

The liver is a large highly vascularized organ with a central function in metabolic homeostasis, detoxification, and immunity. Due to its roles, the liver is frequently exposed to various insults which can cause cell death and hepatic dysfunction. Alternatively, the liver has a remarkable ability to self-repair and regenerate after injury. Liver injury and regeneration have both been linked to complex extracellular matrix (ECM) related pathways. While normal degradation of ECM components is an important feature of tissue repair and remodeling, irregular ECM turnover contributes to a variety of liver diseases. Matrix metalloproteinases (MMPs) are the main enzymes implicated in ECM degradation. MMPs not only remodel the ECM, but also regulate immune responses. In this review, we highlight some of the MMP-attributed roles in acute and chronic liver injury and emphasize the need for further experimentation to better understand their functions during hepatic physiological conditions and disease progression.

Adiponectin reduces hepatic stellate cell migration by promoting tissue inhibitor of metalloproteinase-1 (TIMP-1) secretion

Hepatic stellate cells (HSC) are central players in liver fibrosis that when activated, proliferate, migrate to sites of liver injury, and secrete extracellular matrix. Obesity, a known risk factor for liver fibrosis is associated with reduced levels of adiponectin, a protein that inhibits liver fibrosis in vivo and limits HSC proliferation and migration in vitro. Adiponectin-mediated activation of adenosine monophosphate-activated kinase (AMPK) inhibits HSC proliferation, but the mechanism by which it limits HSC migration to sites of injury is unknown. Here we sought to elucidate how adiponectin regulates HSC motility. Primary rat HSCs were isolated and treated with adiponectin in migration assays. The in vivo actions of adiponectin were examined by treating mice with carbon tetrachloride for 12 weeks and then injecting them with adiponectin. Cell and tissue samples were collected and analyzed for gene expression, signaling, and histology. Serum from patients with liver fibrosis was examined for adiponectin and tissue inhibitor of metalloproteinase-1 (TIMP-1) protein. Adiponectin administration into mice increased TIMP-1 gene and protein expression. In cultured HSCs, adiponectin promoted TIMP-1 expression and through binding of TIMP-1 to the CD63/β1-integrin complex reduced phosphorylation of focal adhesion kinase to limit HSC migration. In mice with liver fibrosis, adiponectin had similar effects and limited focal adhesion kinase phosphorylation. Finally, in patients with advanced fibrosis, there was a positive correlation between serum adiponectin and TIMP-1 levels. In sum, these data show that adiponectin stimulates TIMP-1 secretion by HSCs to retard their migration and contributes to the anti-fibrotic effects of adiponectin.

MiR-29a reduces TIMP-1 production by dermal fibroblasts via targeting TGF-β activated kinase 1 binding protein 1, implications for systemic sclerosis

Background

Systemic sclerosis (SSc) is an autoimmune connective tissue disease characterised by skin and internal organs fibrosis due to accumulation of extra cellular matrix (ECM) proteins. Tissue inhibitor of metalloproteinases 1 (TIMP-1) plays a key role in ECM deposition.

Aim

To investigate the role of miR-29a in regulation of TAB1-mediated TIMP-1 production in dermal fibroblasts in systemic sclerosis.

Methods

Healthy control (HC) and SSc fibroblasts were cultured from skin biopsies. The expression of TIMP-1, MMP-1 and TGF-β activated kinase 1 binding protein 1 (TAB1) was measured following miR-29a transfection using ELISA, qRT-PCR, and Western Blotting. The functional effect of miR-29a on dermal fibroblasts was assessed in collagen gel assay. In addition, HeLa cells were transfected with 3′UTR of TAB1 plasmid cloned downstream of firefly luciferase gene to assess TAB1 activity. HC fibroblasts and HeLa cells were also transfected with Target protectors in order to block the endogenous miR-29a activity.

Results

We found that TAB1 is a novel target gene of miR-29a, also regulating downstream TIMP-1 production. TAB1 is involved in TGF-β signal transduction, a key cytokine triggering TIMP-1 production. To confirm that TAB1 is a bona fide target gene of miR-29a, we used a TAB1 3′UTR luciferase assay and Target protector system. We showed that miR-29a not only reduced TIMP-1 secretion via TAB1 repression, but also increased functional MMP-1 production resulting in collagen degradation. Blocking TAB1 activity by pharmacological inhibition or TAB1 knockdown resulted in TIMP-1 reduction, confirming TAB1-dependent TIMP-1 regulation. Enhanced expression of miR-29a was able to reverse the profibrotic phenotype of SSc fibroblasts via downregulation of collagen and TIMP-1.

Conclusions

miR-29a repressed TAB1-mediated TIMP-1 production in dermal fibroblasts, demonstrating that miR-29a may be a therapeutic target in SSc.

Diverse functions of matrix metalloproteinases during fibrosis

Fibrosis--a debilitating condition that can occur in most organs - is characterized by excess deposition of a collagen-rich extracellular matrix (ECM). At first sight, the activities of proteinases that can degrade matrix, such as matrix metalloproteinases (MMPs), might be expected to be under-expressed in fibrosis or, if present, could function to resolve the excess matrix. However, as we review here, some MMPs are indeed anti-fibrotic, whereas others can have pro-fibrotic functions. MMPs modulate a range of biological processes, especially processes related to immunity and tissue repair and/or remodeling. Although we do not yet know precisely how MMPs function during fibrosis--that is, the protein substrate or substrates that an individual MMP acts on to effect a specific process--experiments in mouse models demonstrate that MMP-dependent functions during fibrosis are not limited to effects on ECM turnover. Rather, data from diverse models indicate that these proteinases influence cellular activities as varied as proliferation and survival, gene expression, and multiple aspects of inflammation that, in turn, impact outcomes related to fibrosis.

TIMP-1 in patients with cirrhosis: relation to liver dysfunction, portal hypertension, and hemodynamic changes

OBJECTIVE

Cirrhotic portal hypertensive patients often develop hemodynamic complications and the diagnosis is often based on liver biopsy and measurements of the hepatic venous pressure gradient (HVPG). Potential noninvasive biomarkers for the severity of cirrhosis are the matrix metalloproteinase and their specific inhibitors such as tissue inhibitor of metalloproteinases-1 (TIMP-1). The aim of the study was to investigate TIMP-1 levels in cirrhosis in relation to the degree of liver dysfunction, portal hypertension, and hemodynamic changes.

MATERIALS AND METHODS

We retrospectively studied 84 patients with cirrhosis and 14 controls without liver disease. All individuals underwent a liver vein catheterization with a hemodynamic assessment. TIMP-1 was determined in arterial and hepatic venous plasma using an MAC-15 TIMP-1 ELISA.

RESULTS

Hepatic venous concentrations of TIMP-1 were significantly increased in patients compared to controls: 336 (166) ng/ml versus 145 (100) (median/IQ range) (p < 0.001) with a progressive increase throughout the Child classes (p < 0.001). Circulating TIMP-1 correlated significantly with indocyanine green clearance (r = -0.44, p < 0.0001), Child Turcotte score (r = 0.50, p < 0.0001), HVPG (r = 0.40, p < 0.0001), mean arterial pressure (r = -0.29, p = 0.008), and systemic vascular resistance (r = -0.23, p = 0.03). Receiver operating characteristic curve analysis enabled us to establish cutoff values for TIMP-1 with regard to portal hypertension.

CONCLUSIONS

TIMP-1 is significantly increased in patients with cirrhosis and correlates with the severity of the disease, degree of portal hypertension, and vasodilatory state. TIMP-1 is therefore a promising new noninvasive marker to predict hemodynamic-related complications in cirrhosis.

Probucol attenuates ethanol-induced liver fibrosis in rats by inhibiting oxidative stress, extracellular matrix protein accumulation and cytokine production

1. Liver fibrosis is characterized by excessive accumulation of extracellular matrix (ECM) proteins in the liver. Probucol, a lipid-lowering drug, was found to prevent liver injury in rats treated with carbon tetrachloride (CCl4 ). In the present study, we investigated whether probucol has protective effect against liver fibrosis in rats treated with ethanol and CCl4 . 2. Thirty rats were randomly divided into five groups. Groups I and II served as the normal control and the model of liver fibrosis, respectively. Groups III-V were treated with probucol at a doses of 250, 500 and 1000 mg/kg, respectively. Rats in Group II were fed a complex diet that includes alcohol, corn oil and pyrazole, and were injected intraperitoneally with CCl4 to induce hepatic fibrosis. Blood was obtained to assess markers of liver function. Liver samples were collected to evaluate mRNA and protein expression, histological changes and oxidative stress. 3. Probucol significantly attenuated the histological changes induced by ethanol + CCl4 and improved liver function. Expression levels of α-smooth muscle actin and collagen I was decreased in the probucol-treated groups. Moreover, probucol markedly suppressed increases in oxidative stress, ECM protein accumulation and cytokine production induced by ethanol + CCl4 . Finally, probucol inhibited activation of the extracellular signal-regulated kinase signalling pathway induced by ethanol + CCl4 . 4. Our findings reveal that probucol attenuates ethanol + CCl4 -induced liver fibrosis by inhibiting oxidative stress, ECM protein accumulation and cytokine production. These data suggest that probucol may be useful for the prevention and treatment of hepatic fibrosis.

Gene expression analysis of murine and human osteoarthritis synovium reveals elevation of transforming growth factor β-responsive genes in osteoarthritis-related fibrosis

OBJECTIVE

Synovial fibrosis is a major contributor to joint stiffness in osteoarthritis (OA). Transforming growth factor β (TGFβ), which is elevated in OA, plays a key role in the onset and persistence of synovial fibrosis. However, blocking of TGFβ in OA as a therapeutic intervention for fibrosis is not an option since TGFβ is crucial for cartilage maintenance and repair. Therefore, we undertook the present study to seek targets downstream of TGFβ for preventing OA-related fibrosis without interfering with joint homeostasis.

METHODS

Experiments were performed to determine whether genes involved in extracellular matrix turnover were responsive to TGFβ and were elevated in OA-related fibrosis. We analyzed gene expression in TGFβ-stimulated human OA synovial fibroblasts and in the synovium of mice with TGFβ-induced fibrosis, mice with experimental OA, and humans with end-stage OA. Gene expression was determined by microarray, low-density array, or quantitative polymerase chain reaction analysis.

RESULTS

We observed an increase in expression of procollagen genes and genes encoding collagen crosslinking enzymes under all of the OA-related fibrotic conditions investigated. Comparison of gene expression in TGFβ-stimulated human OA synovial fibroblasts, synovium from mice with experimental OA, and synovium from humans with end-stage OA revealed that the genes PLOD2, LOX, COL1A1, COL5A1, and TIMP1 were up-regulated in all of these conditions. Additionally, we confirmed that these genes were up-regulated by TGFβ in vivo in mice with TGFβ-induced synovial fibrosis.

CONCLUSION

Most of the up-regulated genes identified in this study would be poor targets for therapy development, due to their crucial functions in the joint. However, the highly up-regulated gene PLOD2, responsible for the formation of collagen crosslinks that make collagen less susceptible to enzymatic degradation, is an attractive and promising target for interference in OA-related synovial fibrosis.

Reversal, maintenance or progression: what happens to the liver after a virologic cure of hepatitis C?

A sustained virological response (SVR) from HCV (synonymous with virological cure) leads to decreased mortality, morbidity and improved quality of life, as well as a reduced incidence of liver disease progression, including liver failure, cirrhosis and hepatocellular carcinoma. Large clinical trials comparing pre- and post-treatment liver biopsies demonstrate improvements in inflammation as well as fibrosis score following SVR. However, a small subset of patients display persistent hepatic inflammation and/or progress to cirrhosis despite SVR. In addition to conferring a risk of fibrosis progression, advanced fibrosis pre-treatment is a major risk factor for post-SVR hepatocellular carcinoma. In this review, we discuss the mechanisms of fibrosis regression uncovered using experimental fibrosis models and highlight potential mechanisms in those few patients with fibrosis progression despite SVR. We also introduce current concepts of fibrosis-dependent tumorigenesis post-SVR in patients with advanced disease. This article forms part of a symposium in Antiviral Research on "Hepatitis C: next steps toward global eradication."

Translational profiles of medullary myofibroblasts during kidney fibrosis

Myofibroblasts secrete matrix during chronic injury, and their ablation ameliorates fibrosis. Development of new biomarkers and therapies for CKD will be aided by a detailed analysis of myofibroblast gene expression during the early stages of fibrosis. However, dissociating myofibroblasts from fibrotic kidney is challenging. We therefore adapted translational ribosome affinity purification (TRAP) to isolate and profile mRNA from myofibroblasts and their precursors during kidney fibrosis. We generated and characterized a transgenic mouse expressing an enhanced green fluorescent protein (eGFP)-tagged L10a ribosomal subunit protein under control of the collagen1α1 promoter. We developed a one-step procedure for isolation of polysomal RNA from collagen1α1-eGFPL10a mice subject to unilateral ureteral obstruction and analyzed and validated the resulting transcriptional profiles. Pathway analysis revealed strong gene signatures for cell proliferation, migration, and shape change. Numerous novel genes and candidate biomarkers were upregulated during fibrosis, specifically in myofibroblasts, and we validated these results by quantitative PCR, in situ, and Western blot analysis. This study provides a comprehensive analysis of early myofibroblast gene expression during kidney fibrosis and introduces a new technique for cell-specific polysomal mRNA isolation in kidney injury models that is suited for RNA-sequencing technologies.

Hepatic inflammation and progressive liver fibrosis in chronic liver disease

Chronic liver inflammation drives hepatic fibrosis, and current immunosuppressive, anti-inflammatory, and anti-viral therapies can weaken this driver. Hepatic fibrosis is reversed, stabilized, or prevented in 57%-79% of patients by conventional treatment regimens, mainly by their anti-inflammatory actions. Responses, however, are commonly incomplete and inconsistently achieved. The fibrotic mechanisms associated with liver inflammation have been clarified, and anti-fibrotic agents promise to improve outcomes as adjunctive therapies. Hepatitis C virus and immune-mediated responses can activate hepatic stellate cells by increasing oxidative stress within hepatocytes. Angiotensin can be synthesized by activated hepatic stellate cells and promote the production of reactive oxygen species. Anti-oxidants (N-acetylcysteine, S-adenosyl-L-methionine, and vitamin E) and angiotensin inhibitors (losartin) have had anti-fibrotic actions in preliminary human studies, and they may emerge as supplemental therapies. Anti-fibrotic agents presage a new era of supplemental treatment for chronic liver disease.

Gelatinase B/MMP-9 in Tumour Pathogenesis and Progression

Since its original identification as a leukocyte gelatinase/type V collagenase and tumour type IV collagenase, gelatinase B/matrix metalloproteinase (MMP)-9 is now recognised as playing a central role in many aspects of tumour progression. In this review, we relate current concepts concerning the many ways in which gelatinase B/MMP-9 influences tumour biology. Following a brief outline of the gelatinase B/MMP-9 gene and protein, we analyse the role(s) of gelatinase B/MMP-9 in different phases of the tumorigenic process, and compare the importance of gelatinase B/MMP-9 source in the carcinogenic process. What becomes apparent is the importance of inflammatory cell-derived gelatinase B/MMP-9 in tumour promotion, early progression and triggering of the "angiogenic switch", the integral relationship between inflammatory, stromal and tumour components with respect to gelatinase B/MMP-9 production and activation, and the fundamental role for gelatinase B/MMP-9 in the formation and maintenance of tumour stem cell and metastatic niches. It is also apparent that gelatinase B/MMP-9 plays important tumour suppressing functions, producing endogenous angiogenesis inhibitors, promoting inflammatory anti-tumour activity, and inducing apoptosis. The fundamental roles of gelatinase B/MMP-9 in cancer biology underpins the need for specific therapeutic inhibitors of gelatinase B/MMP-9 function, the use of which must take into account and substitute for tumour-suppressing gelatinase B/MMP-9 activity and also limit inhibition of physiological gelatinase B/MMP-9 function.

Hepatic apoptosis can modulate liver fibrosis through TIMP1 pathway

Apoptotic injury participates in hepatic fibrosis, but the molecular mechanisms are not well understood. The present study aimed to investigate the role of inducible TIMP1 in the pathogenesis of hepatic apoptosis-fibrosis. Apoptosis was induced with GCDC, LPS, and alcohol in precision-cut liver slices or bile duct ligation (BDL) in rats, as reflected by caspase-3 activity, TUNEL assay, and apoptosis-related gene profiles. The hepatic fibrosis was detected with Picrosirius staining, hydroxyproline determination, and expression profiling of fibrosis-related genes. Levels of TIMP1 were upregulated by the hepatic apoptosis, but downregulated by caspase inhibitor. The inducible TIMP1 was apoptosis-dependent. Once TIMP1 was inhibited with treatment of TIMP1-siRNA, the fibrotic response was reduced as demonstrated by hydroxyproline assay. In addition, the expression of fibrosis-related genes aSMA, CTGF, and TGFb2r were down-regulated subsequent to the treatment of TIMP1-siRNA. TIMP1 could mediate the expression of fibrosis-related genes. TIMP1 was transcriptionally regulated by nuclear factor c-Jun as demonstrated by EMSA and ChIP assay. The treatment of c-Jun siRNA could significantly decrease the expression of TIMP1 induced by alcohol, GCDC, or LPS treatment. Hepatic apoptosis induces the expression of TIMP1. Inducible TIMP1 can modulate the expression of fibrosis-related genes in liver. TIMP1 pathway is a potential target for therapeutic intervention of fibrotic liver diseases.

Combined taurine, epigallocatechin gallate and genistein therapy reduces HSC-T6 cell proliferation and modulates the expression of fibrogenic factors

Hepatic fibrogenesis involves the activation of hepatic stellate cells (HSCs), which synthesize excess extracellular matrix and contribute to the development of liver fibrosis. In a prior study we tested the effect of combined treatment with taurine, epigallocatechin gallate and genistein on the development of alcohol-induced liver fibrosis in vitro. In this study, the biological activity of the combination of these molecules was assessed by measuring its effect on cell proliferation, fibrosis-related gene expression, and proteomic expression profiling in the activated HSC cell line, HSC-T6. HSC-T6 cells were incubated with different concentrations of the drug combination taurine, epigallocatechin gallate and genistein. Cell proliferation was evaluated by MTT assay. Transforming growth factor β1 (TGF-β1), collagen type I (Col-I), matrix metalloproteinase-2 (MMP-2), and tissue inhibitor of metalloproteinases 1 and 2 (TIMP-1 and TIMP-2) mRNA were analyzed by semi-quantitative reverse-transcription PCR. Proteomic profiling of HSC-T6 cells was also performed by SELDI-TOF-MS. Combined drug treatment significantly inhibited cell proliferation and TGF-β1, Col-I, TIMP-1 and TIMP-2 mRNA expression in activated HSC-T6 cells, while the expression of MMP-2 mRNA increased. A total of 176 protein m/z peaks were identified. The intensities of 10 protein peaks were downregulated and two protein peaks were upregulated in HSC-T6 cells after combined drug treatment. In conclusion, combined drug treatment with taurine, epigallocatechin gallate and genistein can inhibit HSC proliferation, and impact fibrosis-related gene and protein expression. The antifibrotic effects of this drug combination may be due to its effects on the expression of fibrogenic genes.

Peroxisome proliferator-activated receptor-γ activators monascin and rosiglitazone attenuate carboxymethyllysine-induced fibrosis in hepatic stellate cells through regulating the oxidative stress pathway but independent of the receptor for advanced glycation end products signaling

Advanced glycation end products (AGEs) signaling through its receptors (RAGE) results in an increase in reactive oxygen species (ROS) and is thought to contribute to hepatic fibrosis via hyperglycemia. Carboxymethyllysine (CML) is a key AGE, with highly reactive dicarbonyl metabolites. We investigated the inhibitory effect of Monascus -fermented metabolite monascin and rosiglitazone on CML-induced RAGE signaling in hepatic stellate cells (HSCs) and its resulting antihepatic fibrosis activity. We found that monascin and rosiglitazone upregulated peroxisome proliferator-activated receptor-γ (PPAR-γ) to attenuate α-smooth muscle actin (SMA) and ROS generation in CML-treated HSCs in a RAGE activation-independent pathway. Therefore, monascin may delay or inhibit the progression of liver fibrosis through the activation of PPAR-γ and might prove to be a major antifibrotic mechanism to prevent liver disease.

Role of matrix metalloproteinases and tissue inhibitor of metalloproteinases type-1 in the development of alcoholic liver fibrosis in rats

AIM: To study the role of matrix metalloproteinases and tissue inhibitor of metalloproteinases type-1 in alcoholic liver fibrosis (ALF) in rats by dynamically monitoring their expression in ALF.

METHODS: SD rats were randomly divided into three groups: a control group, a CCl₄ group and an experimental group. The experiment group was intragastrically given a mixture (560 mL/L alcohol, 10 mL/kg; corn oil 2 mL/kg; pyrazole 25 mg/kg) once a day and an intraperitoneal injection of 0.3 mL/kg 25% CCl4 solution (in olive oil) twice a week. The CCl₄ group received an intraperitoneal injection of CCl₄ solution and was intragastrically given equal volume of normal saline (12 mL/kg per day). The control group was given equal volume of normal saline both intraperitoneally and intragastrically. The rats were anaesthetized and killed 4, 8, 10 and 12 wk after modeling. Serum levels of ALT and AST were measured. Pathological changes in liver tissues were observed. The expression of MMP2, MMP9 and TIMP-1 was detected by Western blot and real-time PCR.

RESULTS: Compared to the control group, the CCl₄ group showed no significant changes in body weight, liver weight, liver/body weight ratio and serum transaminase levels, but the experimental group had significantly decreased body weight and significantly increased liver weight, liver/body weight ratio and serum transaminases. In the experimental group, with the increase in the severity of liver fibrosis, MMP2, MMP9 and TIMP-1 levels were gradually elevated, and expression of TIMP-1 increased more obviously than that of MMP2 and MMP9.

CONCLUSION: MMP2, MMP9 and TIMP-1 may play an important role in the pathogenesis of ALF in rats.

Tumor necrosis factor-α promotes cholestasis-induced liver fibrosis in the mouse through tissue inhibitor of metalloproteinase-1 production in hepatic stellate cells

Tumor necrosis factor (TNF)-α, which is a mediator of hepatotoxicity, has been implicated in liver fibrosis. However, the roles of TNF-α on hepatic stellate cell (HSC) activation and liver fibrosis are complicated and remain controversial. To explore this issue, the role of TNF-α in cholestasis-induced liver fibrosis was examined by comparing between TNF-α(-/-) mice and TNF-α(+/+) mice after bile duct ligation (BDL). Serum TNF-α levels in mice were increased by common BDL combined with cystic duct ligation (CBDL+CDL). TNF-α deficiency reduced liver fibrosis without affecting liver injury, inflammatory cell infiltration, and liver regeneration after CBDL+CDL. Increased expression levels of collagen α1(I) mRNA, transforming growth factor (TGF)-β mRNA, and α-smooth muscle actin (αSMA) protein by CBDL+CDL in the livers of TNF-α(-/-) mice were comparable to those in TNF-α(+/+) mice. Exogenous administration of TNF-α decreased collagen α1(I) mRNA expression in isolated rat HSCs. These results suggest that the reduced fibrosis in TNF-α(-/-) mice is regulated in post-transcriptional level. Tissue inhibitor of metalloproteinase (TIMP)-1 plays a crucial role in the pathogenesis of liver fibrosis. TIMP-1 expression in HSCs in the liver was increased by CBDL+CDL, and the induction was lower in TNF-α(-/-) mice than in TNF-α(+/+) mice. Fibrosis in the lobe of TIMP-1(-/-) mice with partial BDL was also reduced. These findings indicate that TNF-α produced by cholestasis can promote liver fibrosis via TIMP-1 production from HSCs. Thus, targeting TNF-α and TIMP-1 may become a new therapeutic strategy for treating liver fibrosis in cholestatic liver injury.

A histone deacetylase inhibitor, largazole, decreases liver fibrosis and angiogenesis by inhibiting transforming growth factor-β and vascular endothelial growth factor signalling

BACKGROUND & AIMS

Largazole is a novel histone deacetylase (HDAC) inhibitor. This study investigated the effects of largazole against liver fibrosis.

METHODS

The in vitro effects of largazole were examined using hepatic stellate cells (HSCs). In vivo effects of largazole were studied using a mouse liver fibrotic model induced by CCl4 .

RESULTS

Largazole augmented acetylation of histone H3 (H3) and histone H4 (H4) in HSCs. It directly inhibited the activation of HSCs owing to HDAC inhibitory activity as the antifibrotic effect of largazole was significantly decreased in cells with HDAC1, HDAC2 and HDAC3 knockdown. Largazole also induced apoptosis of HSCs. Largazole not only inhibited the expression of TGFβR2, but also reduced phosphorylation of Smad2 and Akt induced by TGF-β1. Largazole also inhibited the expression of vascular endothelial growth factor (VEGF) and its receptor. VEGF-induced proliferation of HSCs and activation of Akt and p38MAPK were also suppressed by largazole. In vivo, largazole reduced the expression of collagen I, α-smooth muscle actin and tissue inhibitor of metalloproteinase-1 in CCl4 -induced fibrosis, and these antifibrotic effects were associated with increased acetylation of H3 and H4. Largazole also induced HSCs to undergo apoptosis in vivo, which was correlated with downregulation of bcl-2 and bcl-xL. Furthermore, largazole inhibited angiogenesis in vivo as evidenced by reduced expression of CD34, VEGF and VEGFR. In addition to its antifibrotic activity, the drug reduced inflammatory activity in CCl4 -induced liver fibrosis.

CONCLUSIONS

Our findings revealed a novel role of largazole in the treatment of liver fibrosis. Through multiple mechanisms, largazole could be a potentially effective antifibrotic agent.

Portal, but not lobular, macrophages express matrix metalloproteinase-9: association with the ductular reaction and fibrosis in chronic hepatitis C

BACKGROUND

Liver macrophages are a heterogeneous cell population that produces factors involved in fibrogenesis and matrix turnover, including matrix metalloproteinase (MMP) -9. During liver injury, their close proximity to hepatic progenitor cells and the ductular reaction may enable them to regulate liver repair and fibrosis.

AIMS

To enumerate and characterise liver macrophages in patients with chronic hepatitis C, to determine whether a distinct population of macrophages is associated with the ductular reaction and portal fibrosis.

METHODS

Immunostaining for macrophage markers (CD68, CD163, CCR2), the ductular reaction (keratin-7) and MMP-9 was performed in liver biopsy sections from patients with chronic hepatitis C virus (HCV) (n = 85).

RESULTS

Portal tracts were more densely populated with macrophages (10.5 ± 0.36 macrophages/HPF) than lobules (7.2 ± 0.16 macrophages/HPF, P < 0.001) and macrophages were found in close proximity to the ductular reaction. ≥30% of portal and periductal macrophages expressed MMP-9 and these were significantly associated with increasing stage of fibrosis (rs  = 0.58, 0.68, respectively, both P < 0.001). In contrast, MMP-9(+) macrophages were largely absent in lobular regions and non-diseased liver. Hepatic MMP-9 mRNA levels and gelatinolytic activity were significantly associated with stage of fibrosis (rs  = 0.47, rs  = 0.89, respectively, both P < 0.001). Furthermore, a second distinct CCR2(+) macrophage population was localised to the centrilobular regions and was predominantly absent from portal and periductal areas.

CONCLUSIONS

These findings demonstrate significant regional differences in macrophage phenotypes, suggesting that there are at least two populations of liver macrophages. We propose that these populations have distinct contributions to the pathogenesis of chronic HCV-related liver disease.

Tumor progression locus 2/Cot is required for activation of extracellular regulated kinase in liver injury and toll-like receptor-induced TIMP-1 gene transcription in hepatic stellate cells in mice

Toll-like receptors (TLRs) function as key regulators of liver fibrosis and are able to modulate the fibrogenic actions of nonparenchymal liver cells. The fibrogenic signaling events downstream of TLRs on Kupffer cells (KCs) and hepatic stellate cells (HSCs) are poorly defined. Here, we describe the MAP3K tumor progression locus 2 (Tpl2) as being important for the activation of extracellular regulated kinase (ERK) signaling in KCs and HSCs responding to stimulation of TLR4 and TLR9. KCs lacking Tpl2 display defects with TLR induction of cytokines interleukin (IL)-1β, IL-10, and IL-23. tpl2(-/-) HSCs were unable to increase expression of fibrogenic genes IL-1β and tissue inhibitor of metalloproteinase 1 (TIMP-1), with the latter being the result of defective stimulation of TIMP-1 promoter activity by TLRs. To determine the in vivo relevance of Tpl2 signaling in liver fibrosis, we compared the fibrogenic responses of wild-type (WT) and tpl2(-/-) mice in three distinct models of chronic liver injury. In the carbon tetrachloride and methionine-choline-deficient diet models, we observed a significant reduction in fibrosis in mice lacking Tpl2, compared to WT controls. However, in the bile duct ligation model, there was no effect of tpl2 deletion, which may reflect a lesser role for HSCs in wounding response to biliary injury.

CONCLUSION

We conclude that Tpl2 is an important signal transducer for TLR activation of gene expression in KCs and HSCs by the ERK pathway and that suppression of its catalytic activity may be a route toward suppressing fibrosis caused by hepatocellular injuries. (HEPATOLOGY 2013).

Toll-like receptor-mediated, enhanced production of profibrotic TIMP-1 in monocytes from patients with systemic sclerosis: role of serum factors

Objectives

To investigate whether monocytes contribute to matrix deposition in systemic sclerosis (SSc) by production of tissue-inhibitor of metalloproteinase-1 (TIMP-1).

Methods

Matrix metalloproteinase-1 (MMP-1) and TIMP-1 expression and secretion were measured by qRT-PCR and ELISA in circulating monocytes from patients with SSc, patients with rheumatoid arthritis (RA) and healthy controls (HC) and in healthy monocytes cultured in the presence of SSc or HC serum samples. Production of TIMP-1 was determined in response to a panel of Toll-like receptor (TLR) agonists and MyD88 inhibitory peptide. The functional effect of conditioned media from SSc and HC serum samples or TLR8-stimulated monocytes was studied in an MMP-1 activity assay.

Results

TIMP-1 production by monocytes was upregulated in patients with SSc compared with patients with RA and HC. Incubation of HC monocytes with SSc serum samples resulted in functionally active TIMP-1 production. However, pretreatment with MyD88 inhibitor, but not control peptide, decreased TIMP-1 secretion. TIMP-1 production was significantly stronger when SSc and HC monocytes were stimulated with TLR8 (ssRNA) agonist, but the response was more pronounced in SSc monocytes. TIMP-1 production after TLR stimulation was also strongly reduced in the presence of MyD88 inhibitory peptide or in the monocytes isolated from a patient with a genetic TLR signalling defect. MMP-1 activity was significantly inhibited in media from serum samples or TLR8-stimulated monocytes indicative of functional TIMP activity.

Conclusions

This study demonstrates profibrotic properties of circulating monocytes from patients with SSc and a key role for TLR signalling, particularly TLR8, in TIMP-1 secretion and matrix remodelling.

Anchoring hepatic gene expression with development of fibrosis and neoplasia in a toxicant-induced fish model of liver injury

Fish have been used as laboratory models to study hepatic development and carcinogenesis but not for pathogenesis of hepatic fibrosis. In this study, a dimethylnitrosamine-induced fish model of hepatic injury was developed in Japanese medaka (Oryzias latipes) and gene expression was anchored with the development of hepatic fibrosis and neoplasia. Exposed livers exhibited mild hepatocellular degenerative changes 2 weeks' postexposure. Within 6 weeks, hepatic fibrosis/cirrhosis was evident with development of neoplasia by 10 weeks. Stellate cell activation and development of fibrosis was associated with upregulation of transforming growth factor beta 1 (tgfb1), tgfb receptor 2, mothers against decapentaplegic homolog 3 (smad3a), smad3b, beta-catenin (ctnnb1), myc, matrix metalloproteinase (mmp2), mmp14a, mmp14b, tissue inhibitors of metalloproteinase (timp) 2a, timp2b, timp3, collagen type I alpha 1a (col1a1a), and col1a1b and a less pronounced increase in mmp13 and col4a1 expression. Tgfb receptor I expression was unchanged. Immunohistochemistry suggested that biliary epithelial cells and stellate cells were the main producers of TGF-β1. This study identified a group of candidate genes likely to be involved in the development of hepatic fibrosis and demonstrated that the TGF-β pathway likely plays a major role in the pathogenesis. These results support the medaka as a viable fish model of hepatic fibrosis.

Extracellular matrix degradation in liver fibrosis: Biochemistry and regulation

Fibrosis is a highly conserved wound healing response and represents the final common pathway of virtually all chronic inflammatory injuries. Over the past 3 decades detailed analysis of hepatic extracellular matrix synthesis and degradation using approaches incorporating human disease, experimental animal models and cell culture have highlighted the extraordinarily dynamic nature of tissue repair and remodelling in this solid organ. Furthermore emerging studies of fibrosis in other organs demonstrate that basic common mechanisms exist, suggesting that bidirectionality of the fibrotic process may not solely be the preserve of the liver. In this review we will examine the cellular and molecular mechanisms that govern extracellular matrix degradation and fibrosis resolution, and highlight how manipulation of these processes may result in the development of effective anti-fibrotic therapies. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Serum levels of tissue inhibitor of metalloproteinase-1 are correlated with liver fibrosis in patients with chronic hepatitis B

OBJECTIVE

To investigate the relationship between tissue inhibitor of metalloproteinase-1 (TIMP-1) expression and the severity of liver fibrosis in chronic hepatitis B (CHB) patients, and to explore the diagnostic value of serum TIMP-1.

METHODS

A total of 159 CHB patients underwent liver biopsy for the analysis of liver fibrosis stages and inflammation. Serum TIMP-1 was determined by ELISA. Hyaluronic acid (HA), procollagen type III (PCIII), collagen type IV (CIV), laminin (LN), and FIB-4 index were determined and calculated, and diagnostic accuracy was analyzed using receiver operating characteristic (ROC) curve.

RESULTS

Serum levels of TIMP-1 were associated with the grade of liver inflammation in CHB patients (r = 0.695, P < 0.01), especially in those without fibrosis or with stage 1 fibrosis, and were also positively correlated with liver fibrosis in CHB patients (r = 0.854, P < 0.01), particularly in those with inflammation at grade 1, 2 and 3. The area under the ROC curve (AUROC) of serum TIMP-1 was 0.918 for significant liver fibrosis (≥stage 2), and a sensitivity of 89.4% and specificity of 83.6% were obtained with a cut-off value of ≥174.5 ng/mL of serum TIMP-1, which were higher than that of HA, CIV and FIB-4 index.

CONCLUSION

TIMP-1 is a valuable single biomarker for the evaluation of significant fibrosis in CHB patients.

Fra-1/AP-1 transcription factor negatively regulates pulmonary fibrosis in vivo

The Fra-1/AP-1 transcription factor plays a key role in tumor epithelial cell progression; however, its role in pathogenic lung fibrosis remains unclear. In the present study, using a genetic approach (Fra-1 deficient mice), we have demonstrated a novel regulatory (protective) role for Fra-1 in lung fibrosis. We found greater levels of progressive interstitial fibrosis, characterized by increased levels of inflammation, collagen accumulation, and profibrotic and fibrotic gene expression in the lungs of Fra-1^Δ/Δ mice than in those of Fra-1^+/+ mice following bleomycin treatment. Fra-1 knockdown in human lung epithelial cells caused the upregulation of mesenchymal marker N-cadherin, concomitant with a downregulation of the epithelial phenotype marker E-cadherin, under basal conditions and in response to bleomycin and TGF-β1. Furthermore, Fra-1 knockdown caused an enhanced expression of type 1 collagen and the downregulation of collagenase (MMP-1 and MMP-13) gene expression in human lung epithelial cells. Collectively, our findings demonstrate that Fra-1 mediates anti-fibrotic effects in the lung through the modulation of proinflammatory, profibrotic and fibrotic gene expression, and suggests that the Fra-1 transcription factor may be a potential target for pulmonary fibrosis, a progressive disorder with poor prognosis and treatment.

Elastin accumulation is regulated at the level of degradation by macrophage metalloelastase (MMP-12) during experimental liver fibrosis

Elastin has been linked to maturity of liver fibrosis. To date, the regulation of elastin secretion and its degradation in liver fibrosis has not been characterized. The aim of this work was to define elastin accumulation and the role of the paradigm elastase macrophage metalloelastase (MMP-12) in its turnover during fibrosis. Liver fibrosis was induced by either intraperitoneal injections of carbon tetrachloride (CCl(4) ) for up to 12 weeks (rat and mouse) or oral administration of thioacetamide (TAA) for 1 year (mouse). Elastin synthesis, deposition, and degradation were investigated by immunohistochemistry, quantitative polymerase chain reaction (qPCR), western blotting, and casein zymography. The regulation of MMP-12 elastin degradation was defined mechanistically using CD11b-DTR and MMP-12 knockout mice. In a CCl(4) model of fibrosis in rat, elastin deposition was significantly increased only in advanced fibrosis. Tropoelastin expression increased with duration of injury. MMP-12 protein levels were only modestly changed and in coimmunoprecipitation experiments MMP-12 was bound in greater quantities to its inhibitor TIMP-1 in advanced versus early fibrosis. Immunohistochemistry and macrophage depletion experiments indicated that macrophages were the sole source of MMP-12. Exposure of CCl(4) in MMP-12(-/-) mice led to a similar degree of overall fibrosis compared to wildtype (WT) but increased perisinusoidal elastin. Conversely, oral administration of TAA caused both higher elastin accumulation and higher fibrosis in MMP-12(-/-) mice compared with WT.

CONCLUSION

Elastin is regulated at the level of degradation during liver fibrosis. Macrophage-derived MMP-12 regulates elastin degradation even in progressive experimental liver fibrosis. These observations have important implications for the design of antifibrotic therapies.

Human peripheral blood CD34-positive cells enhance therapeutic regeneration of chronically injured liver in nude rats

We investigated whether transplantation of purified human peripheral blood CD34(+) cells could reduce established liver fibrosis and up-regulate therapeutic regeneration. Human peripheral blood CD34(+) cells were isolated from total mononuclear cells of healthy volunteers by magnetic cell sorting. Recipient nude rats were injected intraperitoneally with carbon tetrachloride (CCl(4)) twice weekly for 3 weeks before single administration of CD34(+) cells. CCl(4) was then re-administered twice weekly for 3 more weeks, and the nude rats were sacrificed. Saline (control group), 1 × 10(5) (low-dose group), 5 × 10(5) (middle-dose group), or 2 × 10(6) (high-dose group) CD34(+) cells/kg body weight were intrasplenically transplanted after CCl(4) treatment for 3 weeks. Reverse transcriptase-polymerase chain reaction analysis of the freshly isolated CD34(+) cells revealed the expression of CD31, keratin19, α-smooth muscle actin (α-SMA), and epithelial growth factor, but not other liver related markers. The transplanted cells differentiated into vascular and sinusoidal endothelial cells, and vascular smooth muscle cells. CD34(+) cell transplantation reduced liver fibrosis in a dose-dependent fashion, with decreased collagen type-I and α-SMA-positive cells after 6 weeks of CCl(4) treatment by Mallory's Azan and immunohistochemical staining. Gelatin zymography showed that the expression levels of active matrix metalloproteinase-2 and -9 in CD34(+) cell transplanted livers were significantly stronger than those in saline-infused livers. In recipients of high-doses of CD34(+) cells, the number of PCNA-positive hepatocyte increased 6 weeks after CCl(4) treatment compared with saline-infused livers. We conclude that human peripheral blood CD34(+) cell transplantation halts established liver fibrosis and promotes hepatic regeneration in CCl(4)-induced chronic liver injury.

Endocytic collagen degradation: a novel mechanism involved in protection against liver fibrosis

Fibrosis of the liver and its end-stage, cirrhosis, represent major health problems worldwide. In these fibrotic conditions, activated fibroblasts and hepatic stellate cells display a net deposition of collagen. This collagen deposition is a major factor leading to liver dysfunction, thus making it crucially important to understand both the collagen synthesis and turnover mechanisms in this condition. Here we show that the endocytic collagen receptor, uPARAP/Endo180, is a major determinant in governing the balance between collagen deposition and degradation. Cirrhotic human livers displayed a marked up-regulation of uPARAP/Endo180 in activated fibroblasts and hepatic stellate cells located close to the collagen deposits. In a hepatic stellate cell line, uPARAP/Endo180 was shown to be active in, and required for, the uptake and intracellular degradation of collagen. To evaluate the functional importance of this collagen receptor in vivo, liver fibrosis was induced in uPARAP/Endo180-deficient mice and littermate wild-type mice by chronic CCl(4) administration. A strong up-regulation of uPARAP/Endo180 was observed in wild-type mice, and a quantitative comparison of collagen deposits in the two groups of mice clearly revealed a fibrosis protective role of uPARAP/Endo180. This effect appeared to directly reflect the activity of the collagen receptor, since no compensatory events were noted when comparing the mRNA expression profiles of the two groups of mice in an array system focused on matrix-degrading components. This function of uPARAP/Endo180 defines a novel role of intracellular collagen turnover in fibrosis protection.

Current status of novel antifibrotic therapies in patients with chronic liver disease

Fibrosis accumulation is a dynamic process resulting from a wound-healing response to acute or chronic liver injury of all causes. The cascade starts with hepatocyte necrosis and apoptosis, which instigate inflammatory signaling by chemokines and cytokines, recruitment of immune cell populations, and activation of fibrogenic cells, culminating in the deposition of extracellular matrix. These key elements, along with pathways of transcriptional and epigenetic regulation, represent fertile therapeutic targets. New therapies include drugs specifically designed as antifibrotics, as well as drugs already available with well-established safety profiles, whose mechanism of action may also be antifibrotic. At the same time, the development of noninvasive fibrogenic markers, and techniques (e.g. fibroscan), as well as combined scoring systems incorporating serum and clinical features will allow improved assessment of therapy response. In aggregate, the advances in the elucidation of the biology of fibrosis, combined with improved technologies for assessment will provide a comprehensive framework for design of antifibrotics and their analysis in well-designed clinical trials. These efforts may ultimately yield success in halting the progression of, or reversing, liver fibrosis.

Pokeweed antiviral protein down-regulates Wnt/β-catenin signalling to attenuate liver fibrogenesis in vitro and in vivo

BACKGROUND AND AIM

Pokeweed antiviral protein (PAP) has been regarded as a strong negative regulator of Wnt/β-catenin signalling, which promotes tissue fibrogenesis. Whether PAP inhibits hepatic fibrosis remains unknown. Here, the inhibitory effects of PAP on hepatic fibrosis induced by CCl4 in rats were monitored.

METHODS

Plasmid pXF3H-PAP was transduced into liver in vivo and hepatic stellate cell (HSC-T6) in vitro. Changes in liver pathology were examined by haematoxylin and eosin (H&E) and Masson's trichrome staining. Hepatic function and the levels of hyaluronic acid (HA) and laminin (LN) in serum and hydroxyproline (Hyp) in liver were measured. We also observed the expressions and distribution of α-SMA, TIMP-1, smad3 and β-catenin in HSCs and liver, together with the viability of HSC-T6 cells.

RESULTS

PAP obviously attenuated the histological changes, decreased the content of Hyp in liver and improved liver function in rats (P<0.05). PAP significantly reduced the expressions and distribution of α-SMA and β-catenin in vivo (0.0125 ± 0.002 vs. 0.0374 ± 0.003, 0.0135 ± 0.003 vs. 0.0382 ± 0.004; P<0.05, respectively) and in vitro as well as the cell viability (P<0.05).

CONCLUSIONS

Our results revealed that PAP attenuated liver fibrogenesis through down-regulating the Wnt/β-catenin pathway. It provides us an alternative new strategy for the treatment of hepatic fibrosis.

IκBβ attenuates angiotensin II-induced cardiovascular inflammation and fibrosis in mice

The development of cardiovascular fibrosis is associated with chronic inflammation, where activation of nuclear factor κB (NF-κB) signaling may play a critical role. NF-κB activation is tightly regulated by the cellular inhibitor of κB (IκB) family of proteins, such as IκBα and IκBβ. IκBα and IκBβ display different regulation kinetics in response to inflammatory stimulation. The present study tested the hypothesis that IκBα and IκBβ may have different roles in modulating cardiovascular inflammation and fibrosis, using a model of angiotensin II infusion-induced hypertension in wild-type mice and IκBβ knock-in mice, in which the IκBα gene is replaced by IκBβ cDNA (AKBI). In WT mice, subcutaneous angiotensin II infusion for 7 days induced increased perivascular and interstitial collagen deposition and fibrotic lesions, associated with myocardial interstitial hemosiderin accumulation and extensive macrophage infiltration. These effects of angiotensin II were dramatically limited in AKBI mice. Replacement of IκBα with IκBβ significantly attenuated angiotensin II infusion-induced expression of interleukin 1β, interleukin 6, monocyte chemotactic protein 1, collagen I and III, fibronectin, and tissue inhibitor of metalloproteinase 1 in the hearts. Furthermore, using cultured vascular smooth muscle cells, we demonstrated that interleukin 1β-induced NF-κB activation and monocyte chemotactic protein 1, vascular cell adhesion molecule 1, and tissue inhibitor of metalloproteinase 1 expressions were suppressed in the AKBI cells because of the replacement of IκBα with IκBβ. These results indicate that NF-κB has an essential role in mediating the cardiovascular inflammatory response to angiotensin II and suggest that targeting the balance of IκBα and IκBβ expression might be a novel therapeutic modality in preventing fibrosis in hypertensive cardiovascular disease.

Hepatoprotective effects of Yi Guan Jian, an herbal medicine, in rats with dimethylnitrosamine-induced liver fibrosis

AIMS OF THE STUDY

Yi Guan Jian (YGJ) has long been employed clinically to treat liver fibrosis in traditional Chinese Medicine but the mechanism underlying the regulation has not been clarified in detail. The present investigation was designed to assess the involvement of the fibrosis pathway in dimethylnitrosamine (DMN)-induced liver fibrosis in rats.

MATERIALS AND METHODS

Liver fibrosis was induced by DMN injection (10mg/kg, i.p., given three consecutive days each week) following 4 weeks. YGJ was oral administered (1.8 g/kg daily via gastrogavage for two weeks). Liver sample were subjected to histological and western blot studies. For evaluation of hepatic fibrosis-related factors, collagen α1-I, tissue inhibitor of metalloproteinase-1 (TIMP-1), and α-smooth muscle actin (α-SMA) mRNA and protein levels were analyzed.

RESULTS

YGJ remarkably prevented body weight loss and DMN damage in the liver, and it inhibited the elevation of serum glutamate oxaloacetate transaminase (GOT), and glutamic pyruvic transaminase (GPT). Oral administration of YGJ extract significantly reduced the accumulation of collagen α1-I, TIMP-1, and α-SMA in liver tissues.

CONCLUSIONS

Taken together, these findings indicate that the YGJ Chinese herb showed hepatoprotective and anti-fibrogenic effects against DMN-induced hepatic injury. Our data suggest that the YGJ may be useful in reversing the development of hepatic fibrosis.