Urokinase-type plasminogen activator gene therapy in liver cirrhosis is mediated by collagens gene expression down-regulation and up-regulation of MMPs, HGF and VEGF

Therapeutic potential of macrophage colony-stimulating factor (CSF1) in chronic liver disease

Resident and recruited macrophages control the development and proliferation of the liver. We showed previously in multiple species that treatment with a macrophage colony stimulating factor (CSF1)-Fc fusion protein initiated hepatocyte proliferation and promoted repair in models of acute hepatic injury in mice. Here we investigated the impact of CSF1-Fc on resolution of advanced fibrosis and liver regeneration, utilizing a non-resolving toxin-induced model of chronic liver injury and fibrosis in C57BL/6J mice. Co-administration of CSF1-Fc with exposure to thioacetamide (TAA) exacerbated inflammation consistent with monocyte contributions to initiation of pathology. After removal of TAA, either acute or chronic CSF1-Fc treatment promoted liver growth, prevented progression and promoted resolution of fibrosis. Acute CSF1-Fc treatment was also anti-fibrotic and pro-regenerative in a model of partial hepatectomy in mice with established fibrosis. The beneficial impacts of CSF1-Fc treatment were associated with monocyte-macrophage recruitment and increased expression of remodeling enzymes and growth factors. These studies indicate that CSF1-dependent macrophages contribute to both initiation and resolution of fibrotic injury and that CSF1-Fc has therapeutic potential in human liver disease.

Simultaneous Administration of ADSCs-Based Therapy and Gene Therapy Using Ad-huPA Reduces Experimental Liver Fibrosis

Background and Aims

hADSCs transplantation in cirrhosis models improves liver function and reduces fibrosis. In addition, Ad-huPA gene therapy diminished fibrosis and increased hepatocyte regeneration. In this study, we evaluate the combination of these therapies in an advanced liver fibrosis experimental model.

Methods

hADSCs were expanded and characterized before transplantation. Ad-huPA was simultaneously administrated via the ileac vein. Animals were immunosuppressed by CsA 24 h before treatment and until sacrifice at 10 days post-treatment. huPA liver expression and hADSCs biodistribution were evaluated, as well as the percentage of fibrotic tissue, hepatic mRNA levels of Col-αI, TGF-β1, CTGF, α-SMA, PAI-I, MMP2 and serum levels of ALT, AST and albumin.

Results

hADSCs homed mainly in liver, whereas huPA expression was similar in Ad-huPA and hADSCs/Ad-huPA groups. hADSCs, Ad-huPA and hADSCs/Ad-huPA treatment improves albumin levels, reduces liver fibrosis and diminishes Collagen α1, CTGF and α-SMA mRNA liver levels. ALT and AST serum levels showed a significant decrease exclusively in the hADSCs group.

Conclusions

These results showed that combinatorial effect of cell and gene-therapy does not improve the antifibrogenic effects of individual treatments, whereas hADSCs transplantation seems to reduce liver fibrosis in a greater proportion.

Human urokinase-type plasminogen activator gene-modified bone marrow-derived mesenchymal stem cells attenuate liver fibrosis in rats by down-regulating the Wnt signaling pathway

AIM: To evaluate the therapeutic effects of bone marrow-derived mesenchymal stem cells (BMSCs) with human urokinase-type plasminogen activator (uPA) on liver fibrosis, and to investigate the mechanism of gene therapy.

METHODS: BMSCs transfected with adenovirus-mediated human urokinase plasminogen activator (Ad-uPA) were transplanted into rats with CCl₄-induced liver fibrosis. All rats were sacrificed after 8 wk, and their serum and liver tissue were collected for biochemical, histopathologic, and molecular analyzes. The degree of liver fibrosis was assessed by hematoxylin and eosin or Masson’s staining. Western blot and quantitative reverse transcription-polymerase chain reaction were used to determine protein and mRNA expression levels.

RESULTS: Serum levels of alanine aminotransferase, aminotransferase, total bilirubin, hyaluronic acid, laminin, and procollagen type III were markedly decreased, whereas the levels of serum albumin were increased by uPA gene modified BMSCs treatment. Histopathology revealed that chronic CCl4-treatment resulted in significant fibrosis while uPA gene modified BMSCs treatment significantly reversed fibrosis. By quantitatively analysing the fibrosis area of liver tissue using Masson staining in different groups of animals, we found that model animals with CCl₄-induced liver fibrosis had the largest fibrotic area (16.69% ± 1.30%), while fibrotic area was significantly decreased by BMSCs treatment (12.38% ± 2.27%) and was further reduced by uPA-BMSCs treatment (8.31% ± 1.21%). Both protein and mRNA expression of β-catenin, Wnt4 and Wnt5a was down-regulated in liver tissues following uPA gene modified BMSCs treatment when compared with the model animals.

CONCLUSION: Transplantation of uPA gene modified BMSCs suppressed liver fibrosis and ameliorated liver function and may be a new approach to treating liver fibrosis. Furthermore, treatment with uPA gene modified BMSCs also resulted in a decrease in expression of molecules of the Wnt signaling pathway.

Aminoacyl-tRNA synthetase interacting multi-functional protein 1 attenuates liver fibrosis by inhibiting TGFβ signaling

The aminoacyl-tRNA synthetase interacting multi-functional protein 1 (AIMP1) participates in a variety of cellular processes, including translation, cell proliferation, inflammation and wound healing. Previously, we showed that the N-terminal peptide of AIMP1 (6-46 aa) induced ERK phosphorylation. Liver fibrosis is characterized by excessive deposition of extracellular matrix, which is induced by TGFβ signaling, and activated ERK is known to induce the phosphorylation of SMAD, thereby inhibiting TGFβ signaling. We assessed whether the AIMP1 peptide can inhibit collagen synthesis in hepatic stellate cells (HSCs) by activating ERK. The AIMP1 peptide induced phosphorylation of SMAD2 via ERK activation, and inhibited the nuclear translocation of SMAD, resulting in a reduction of the synthesis of type I collagen. The AIMP1 peptide attenuated liver fibrosis induced by CCl4, in a dose-dependent manner. Masson-Trichrome staining showed that the AIMP1 peptide reduced collagen deposition. Immunohistochemical staining showed that the levels of α-SMA, TGFβ and type I collagen were all reduced by the AIMP1 peptide. Liver toxicity analysis showed that the AIMP1 peptide improved the levels of relevant biological parameters in the blood. These results suggest that AIMP1 peptide may have potential for development as a therapeutic agent to treat liver fibrosis.

Silymarin Accelerates Liver Regeneration after Partial Hepatectomy

Partial hepatectomy (PHx) is a liver regeneration physiological response induced to maintain homeostasis. Liver regeneration evolved presumably to protect wild animals from catastrophic liver loss caused by toxins or tissue injury. Silymarin (Sm) ability to stimulate liver regeneration has been an object of curiosity for many years. Silymarin has been investigated for use as an antioxidant and anticarcinogen. However, its use as a supportive treatment for liver damage is elusive. In this study, we fed silymarin (Sm, 25 mg/kg) to male Sprague-Dawley rats for 7 weeks. Surgical 2/3 PHx was then conducted on the rats at 6 hrs, 24 hrs, and 72 hrs. Western blot and RT-PCR were conducted to detect the cell cycle activities and silymarin effects on hepatic regeneration. The results showed that silymarin enhanced liver regeneration by accelerating the cell cycle in PHx liver. Silymarin led to increased G1 phase (cyclin D1/pRb), S phase (cyclin E/E2F), G2 phase (cyclin B), and M phase (cyclin A) protein and mRNA at 6 hrs, 24 hrs, and 72 hrs PHx. HGF, TGFα, and TGFβ1 growth factor expressions were also enhanced. We suggest that silymarin plays a crucial role in accelerated liver regeneration after PHx.

Protective mechanisms of medicinal plants targeting hepatic stellate cell activation and extracellular matrix deposition in liver fibrosis

During chronic liver injury, hepatic stellate cells (HSC) are activated and proliferate, which causes excessive extracellular matrix (ECM) deposition, leading to scar formation and fibrosis. Medicinal plants are gaining popularity as antifibrotic agents, and are often safe, cost-effective, and versatile. This review aims to describe the protective role and mechanisms of medicinal plants in the inhibition of HSC activation and ECM deposition during the pathogenesis of liver fibrosis. A systematic literature review on the anti-fibrotic mechanisms of hepatoprotective plants was performed in PubMed, which yielded articles about twelve relevant plants. Many of these plants act via disruption of the transforming growth factor beta 1 signaling pathway, possibly through reduction in oxidative stress. This reduction could explain the inhibition of HSC activation and reduction in ECM deposition. Medicinal plants could be a source of anti-liver fibrosis compounds.

Production of factor VIII by human liver sinusoidal endothelial cells transplanted in immunodeficient uPA mice

Liver sinusoidal endothelial cells (LSECs) form a semi-permeable barrier between parenchymal hepatocytes and the blood. LSECs participate in liver metabolism, clearance of pathological agents, immunological responses, architectural maintenance of the liver and synthesis of growth factors and cytokines. LSECs also play an important role in coagulation through the synthesis of Factor VIII (FVIII). Herein, we phenotypically define human LSECs isolated from fetal liver using flow cytometry and immunofluorescence microscopy. Isolated LSECs were cultured and shown to express endothelial markers and markers specific for the LSEC lineage. LSECs were also shown to engraft the liver when human fetal liver cells were transplanted into immunodeficient mice with liver specific expression of the urokinase-type plasminogen activator (uPA) transgene (uPA-NOG mice). Engrafted cells expressed human Factor VIII at levels approaching those found in human plasma. We also demonstrate engraftment of adult LSECs, as well as hepatocytes, transplanted into uPA-NOG mice. We propose that overexpression of uPA provides beneficial conditions for LSEC engraftment due to elevated expression of the angiogenic cytokine, vascular endothelial growth factor. This work provides a detailed characterization of human midgestation LSECs, thereby providing the means for their purification and culture based on their expression of CD14 and CD32 as well as a lack of CD45 expression. The uPA-NOG mouse is shown to be a permissive host for human LSECs and adult hepatocytes, but not fetal hepatoblasts. Thus, these mice provide a useful model system to study these cell types in vivo. Demonstration of human FVIII production by transplanted LSECs encourages further pursuit of LSEC transplantation as a cellular therapy for the treatment of hemophilia A.

Fasting reduces liver fibrosis in a mouse model for chronic cholangiopathies

Chronic cholangiopathies often lead to fibrosis, as a result of a perpetuated wound healing response, characterized by increased inflammation and excessive deposition of proteins of the extracellular matrix. Our previous studies have shown that food deprivation suppresses the immune response, which led us to postulate its beneficial effects on pathology in liver fibrosis driven by portal inflammation. We investigated the consequences of fasting on liver fibrosis in Abcb4(-/-) mice that spontaneously develop it due to a lack of phospholipids in bile. The effect of up to 48h of food deprivation was studied by gene expression profiling, (immuno)histochemistry, and biochemical assessments of biliary output, and hepatic and plasma lipid composition. In contrast to increased biliary output in the wild type counterparts, bile composition in Abcb4(-/-) mice remained unchanged with fasting and did not influence the attenuation of fibrosis. Markers of inflammation, however, dramatically decreased in livers of Abcb4(-/-) mice already after 12h of fasting. Reduced presence of activated hepatic stellate cells and actively increased tissue remodeling further propelled a decrease in parenchymal fibrosis in fasting. This study is the first to show that food deprivation positively influences liver pathology in a fibrotic mouse model for chronic cholangiopathies, opening a door for new strategies to improve liver regeneration in chronic disease.

Coexpression of Smad7 and UPA attenuates carbon tetrachloride-induced rat liver fibrosis

Background

There is a great need for developing novel therapies to treat liver fibrosis. Previous studies showed that both Smad7 and uPA were inhibitors of liver fibrosis. Therefore, we explored the therapeutic effects of combinational gene therapy with Smad7 and uPA on CCl4-induced liver fibrosis.

Material/Methods

Smad7 and uPA genes were cloned into an adenovirus vector. To observe the therapeutic effects of coexpression of Smad7 and uPA genes, the recombinant adenovirus were delivered into CCL4-induced fibrosis models. Fibrillar collagen, hydroxyproline, α-SMA, TGF-β₁, MMP-13, TIMP-1, HGF and PCNA were detected to evaluate the fibrosis and to explore the mechanisms underlying the treatment with Smad7 and uPA.

Results

The results showed that single Smad7 or uPA adenovirus reduced CCL4 induced liver fibrosis significantly; while combination of Smad7 and uPA had more significant therapeutic effect on CCl4 induced liver fibrosis. Then the markers underlying the therapeutic effect of combination of Smad7 and uPA were also explored. Over-expression of Smad7 and uPA inhibited the expression of α-SMA and TGF-β₁ significantly. Combinational gene therapy also enhanced extracellular matrix degradation by increasing the expression of MMP-13, inhibiting TIMP-1 expression, and promoted hepatocyte proliferation, while single Smad7 or uPA only induced part of these changes.

Conclusions

These results suggest that combinational gene therapy with Smad7 and uPA inhibited CCl4-induced rat liver fibrosis by simultaneously targeting multiple pathogenic pathways.

siRNA against plasminogen activator inhibitor-1 ameliorates bleomycin-induced lung fibrosis in rats

AIM

Plasminogen activator inhibitor-1 (PAI-1) is involved in the progression of pulmonary fibrosis. The present study was undertaken to examine the effects on pulmonary fibrosis of silencing PAI-1 expression with small interfering RNA (siRNA) and to assess the possible underlying mechanisms.

METHODS

Male Wistar rats were subjected to intratracheal injection of bleomycin (BLM, 5 mg/kg, 0.2 mL) to induce pulmonary fibrosis. Histopathological changes of lung tissue were examined with HE or Masson's trichrome staining. The expression levels of α-smooth muscle actin (α-SMA), collagen type-I and type-III, caspase-3, as well as p-ERK1/2 and PI3K/Akt in the lung tissue were evaluated using imunohistochemistry and Western blot analyses. The fibroblasts isolated from BLM-induced fibrotic lung tissue were cultured and transfected with pcDNA-PAI-1 or PAI-1siRNA. The expression level of PAI-1 in the fibroblasts was measured using real time RT-PCR and Western blot analysis. The fibroblast proliferation was evaluated using MTT assay.

RESULTS

Intratracheal injection of PAI-1-siRNA (7.5 nmoL/0.2 mL) significantly alleviated alveolitis and collagen deposition, reduced the expression of PAI-1, α-SMA, collagen type-I and collagen type-III, and increased the expression of caspase-3 in BLM-induced fibrotic lung tissue. In consistence with the in vivo results, the proliferation of the cultured fibroblasts from BLM-induced fibrotic lung tissue was inhibited by transfection with PAI-1-siRNA, and accelerated by overexpression of PAI-1 by transfection with pcDNA-PAI-1. The expression of caspase-3 was increased as a result of PAI-1 siRNA transfection, and decreased after transfection with pcDNA-PAI-1. In addition, the levels of p-ERK1/2 and PI3K/Akt in the fibrogenic lung tissue were reduced after treatment with PAI-1siRNA.

CONCLUSION

The data demonstrate that PAI-1 siRNA inhibits alveolitis and pulmonary fibrosis in BLM-treated rats via inhibiting the proliferation and promoting the apoptosis of fibroblasts. Suppression ERK and AKT signalling pathways might have at least partly contributed to this process. Targeting PAI-1 is a promising therapeutic strategy for pulmonary fibrosis.

High levels of serum VEGF and TIMP-1 are correlated with colon cancer liver metastasis and intrahepatic recurrence after liver resection

The purpose of this study was to develop predictive/prognostic markers for liver metastasis and recurrence following liver resection, investigating not only clinical parameters but also molecular markers that are known to be involved in the process of liver metastasis. Seventy colon cancer patients with either no distant metastasis (group A) or with resectable synchronous liver metastasis only (group B) were prospectively enrolled. All 70 patients received curative resection of the primary tumor. Group B patients underwent additional liver resection. Clinical parameters as well as serum levels of molecular markers [carcinoembryonic antigen (CEA), osteopontin, matrix metalloproteinase-7 (MMP-7), tissue inhibitor of metalloproteinase-1 (TIMP-1), hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and E-selectin] from both tumor drainage (DV) and peripheral veins (PV) were analyzed. Results showed the clinical parameters were not significantly different between groups A and B. Nonetheless, the levels of VEGF and TIMP-1 from both DV and PV were significantly higher in group B compared to group A. In group A, 10 out of 33 (27.0%) patients developed metachronous liver metastasis. High levels of VEGF and TIMP-1 from DV were found to be significantly correlated with metachronous liver metastasis. In group B, 20 out of 33 (60.6%) patients had intrahepatic recurrence following resection of synchronous liver metastasis. The levels of VEGF from DV and the levels of TIMP-1 both from PV and DV were found to be significantly correlated with intrahepatic recurrence. Forty patients (7 from group A and 33 from group B) had liver resection and their 5-year disease-free survival rate was 15.9%. Univariate and multivariate analyses of prognostic factors revealed that the levels of VEGF and TIMP-1 from DV as well as the presence of lymph node metastasis from the primary tumor, synchronous metastasis and R1 resection were significantly associated with worse prognosis. The colon cancer patients with high levels of VEGF and TIMP-1 detected from the DV at the time of their initial surgery were found to have a high risk of metachronous liver metastasis and hepatic recurrence following the resection of synchronous liver metastasis. The high levels of VEGF and TIMP-1 were found to be significant predictive factors for poor prognosis following liver resection. These results require validation but pave the way for future transitional or clinical studies that may provide a greater understanding of colon cancer liver metastasis.

Tissue inhibitor of metalloproteinases-1-induced scattered liver metastasis is mediated by host-derived urokinase-type plasminogen activator

Paradoxically, not only proteinases but also their inhibitors can correlate with bad prognosis of cancer patients, underlining the evolving concept of the protease web as the complex interplay between proteinases, their inhibitors and effector molecules. Elevated levels of tissue inhibitor of metalloproteinases-1 (TIMP-1) render the liver more susceptible to metastasis by triggering urokinase plasminogen activator (uPA) expression as well as hepatocyte growth factor (HGF) signalling, thereby leading to the fatal scattered infiltration of metastasizing tumour cells throughout the parenchyma of the target organ. Here, we investigated whether host uPA is a crucial protagonist for the TIMP-1-induced modulation of a pro-metastatic microenvironment in the liver. Indeed, in livers of uPA-ablated mice elevated TIMP-1 levels did not trigger HGF signalling and did not promote metastasis of a murine T-lymphoma cell line. In contrast, lack of tumour cell-derived uPA induced by gene silencing did not interfere with this pro-metastatic pathway. Furthermore, host uPA was necessary for the recruitment of neutrophilic granulocytes and the associated increase of HGF in livers with elevated TIMP-1 levels. This newly identified co-operation between TIMP-1 and host uPA suggests that therapies, simultaneously interfering with pro- and anti-proteolytic pathways may be beneficial for patients with metastatic disease.

Combinatorial gene therapy renders increased survival in cirrhotic rats

Background

Liver fibrosis ranks as the second cause of death in México's productive-age population. This pathology is characterized by acummulation of fibrillar proteins in hepatic parenchyma causing synthetic and metabolic disfunction. Remotion of excessive fibrous proteins might result in benefit for subjects increasing survival index. The goal of this work was to find whether the already known therapeutical effect of human urokinase Plasminogen Activator and human Matrix Metalloprotease 8 extends survival index in cirrhotic animals.

Methods

Wistar rats (80 g) underwent chronic intoxication with CCl₄: mineral oil for 8 weeks. Cirrhotic animals were injected with a combined dose of Ad-delta-huPA plus Ad-MMP8 (3 × 10¹¹ and 1.5 × 10¹¹ vp/Kg, respectively) or with Ad-beta-Gal (4.5 × 10¹¹) and were killed after 2, 4, 6, 8 and 10 days. Then, liver and serum were collected. An additional set of cirrhotic animals injected with combined gene therapy was also monitored for their probability of survival.

Results

Only the cirrhotic animals treated with therapeutical genes (Ad-delta-huPA+Ad-MMP-8) showed improvement in liver fibrosis. These results correlated with hydroxyproline determinations. A significant decrement in alpha-SMA and TGF-beta1 gene expression was also observed. Cirrhotic rats treated with Ad-delta-huPA plus Ad-MMP8 had a higher probability of survival at 60 days with respect to Ad-beta-Gal-injected animals.

Conclusion

A single administration of Ad-delta-huPA plus Ad-MMP-8 is efficient to induce fibrosis regression and increase survival in experimental liver fibrosis.

Plasmin plays a key role in the regulation of profibrogenic molecules in hepatic stellate cells

BACKGROUND

Plasmin role in transforming growth factor-beta (TGF-beta)-responsive gene regulation remains to be elucidated. Also, plasmin action on co-repressor Ski-related novel protein N (SnoN) and differential activation of matrix metalloproteinases (MMPs) are unknown. Thus, the role of plasmin on profibrogenic molecule expression, SnoN transcriptional kinetics and gelatinase activation was investigated.

METHODS

Hepatic stellate cells (HSC) were transduced with adenovirus-mediated human urokinase plasminogen activator (Ad-huPA) (4 x 10(9) viral particles/ml). Overexpression of urokinase plasminogen activator and therefore of plasmin, was blocked by tranexamic acid (TA) in transduced HSC. Gene expression was monitored by reverse transcriptase polymerase chain reaction. HSC-free supernatants were used to evaluate MMP-2 and MMP-9 by zymography. SnoN, TGF-beta and tissue inhibitor of metalloproteinase (TIMP)-1 were analysed by Western blot. Plasmin and SnoN expression kinetics were evaluated in bile duct-ligated (BDL) rats.

RESULTS

Plasmin overexpression in Ad-huPA-transduced HSC significantly decreased gene expression of profibrogenic molecules [alpha1(I)collagen 66%, TIMP-1 59%, alpha-smooth muscle actin 90% and TGF-beta 55%]. Interestingly, both SnoN gene and protein expression increased prominently. Plasmin inhibition by TA upregulated the profibrogenic genes, which respond to TGF-beta-intracellular signalling. In contrast, SnoN mRNA and protein dropped importantly. Plasmin-activated MMP-9 and MMP-2 in HSC supernatants. Taken together, these findings indicate that MMP-9 activation is totally plasmin dependent. SnoN levels significantly decreased in cholestatic-BDL rats (82%) as compared with control animals. Interestingly, hepatic plasmin levels dropped 46% in BDL rats as compared with control.

CONCLUSION

Plasmin plays a key role in regulating TGF-beta-responding genes. In particular, regulation of TGF-beta-co-repressor (SnoN) is greatly affected, which suggests SnoN as a cardinal player in cholestasis-induced fibrogenesis.

Adenovirus-mediated transfer of siRNA against PAI-1 mRNA ameliorates hepatic fibrosis in rats

BACKGROUND/AIMS

Plasminogen activator inhibitor-1 (PAI-1) is a potential profibrotic molecule. The aim of this study was to evaluate the therapeutic effect of PAI-1 small interfering RNA (siRNA) on experimental hepatic fibrosis and investigate the intrinsic mechanisms.

METHODS

Hepatic fibrosis in rats was induced by dimethylnitrosamine (DMN) administration or bile duct ligation (BDL). An adenovirus carrying PAI-1 shRNA (AdshPAI) was generated and administered via tail vein injection. The expression of PAI-1 was confirmed by real-time RT-PCR and immunohistochemistry. The effect of AdshPAI on fibrosis was evaluated by histological and immunohistochemical examination.

RESULTS

We found that PAI-1 was downregulated after AdshPAI administration. Liver fibrosis was significantly improved after AdshPAI administration in both DMN and BDL models. AdshPAI treatment facilitated matrix degradation by correcting the levels of matrix metalloproteinases (MMPs) and its inhibitors (TIMPs) through upregulation of MMP9, MMP13 and downregulation of TIMP-1. Moreover, AdshPAI treatment stimulated hepatocellular proliferation and inhibited cellular apoptosis.

CONCLUSIONS

This study suggests that AdshPAI treatment has a protective effect on hepatocytes and ameliorates liver fibrogenesis. Inhibiting the upregulation of PAI-1 during liver fibrosis may be an antifibrotic pathway worth exploiting.

Inhibition of plasminogen activator inhibitor-1 expression by siRNA in rat hepatic stellate cells

BACKGROUND AND AIM

The plasminogen activator/plasmin system is known to regulate the extracellular matrix turnover. The aim of this study was to detect the role of plasminogen activator inhibitor-1 (PAI-1) during liver fibrogenesis and investigate the functional effects of PAI-1 gene silencing in rat hepatic stellate cells (HSCs) using small interfering RNA (siRNA).

METHODS

Hepatic fibrosis in rats was induced through serial subcutaneously injections of CCl(4) and the expression of PAI-1 was detected by immunohistochemistry and reverse transcription-polymerase chain reaction (PCR). PAI-1 siRNA molecules were constructed and transiently transfected into HSC-T6 using the cell suspension transfection method. The pSUPER RNA interfering system was used to establish the HSC stable cell line pSUPER-shPAI. Expression of alpha-smooth muscle actin, transforming growth factor-beta, tissue inhibitor of metalloproteinases-1, and collagen types I and III were evaluated by real-time PCR. Cell proliferation and the cell cycle were determined by the methyl thiazolyl tetrazolium (MTT) method and flow cytometry. Collagen content in HSCs supernatant was evaluated by enzyme-linked immunosorbent assay.

RESULTS

The results showed that PAI-1 was upregulated during liver fibrosis, and its expression was closely correlated with the deposition of collagens. SiRNA molecules were successfully transfected into HSCs and induced inhibition of PAI-1 expression time dependently. Moreover, PAI-1 siRNA treatment downregulated alpha-smooth muscle actin, transforming growth factor-beta, tissue inhibitor of metalloproteinases-1 expression, and inhibited collagen types I and III synthesis both at the mRNA and protein level in transiently and stably transfected HSCs.

CONCLUSIONS

This study suggests a significant functional role for PAI-1 in the development of liver fibrosis and that downregulating PAI-1 expression might present as a potential strategy to treat liver fibrosis.

Fibrosis and cirrhosis reversibility - molecular mechanisms

The concept that liver fibrosis is a dynamic process with potential for regression as well as progression has emerged in parallel with clinical evidence for remodeling of fibrotic extracellular matrix in patients who can be effectively treated for their underlying cause of liver disease. This article reviews recent discoveries relating to the cellular and molecular mechanisms that regulate fibrosis regression, with emphasis on studies that have used experimental in vivo models of liver disease. Apoptosis of hepatic myofibroblasts is discussed. The functions played by transcription factors, receptor-ligand interactions, and cell-matrix interactions as regulators of the lifespan of hepatic myofibroblasts are considered, as are the therapeutic opportunities for modulating these functions. Growth factors, proteolytic enzymes, and their inhibitors are discussed in detail.

Molecular mechanism of hepatic stellate cell activation and antifibrotic therapeutic strategies

Activation of hepatic stellate cells (HSCs) is the dominant event in liver fibrosis. The early events in the organization of HSC activation have been termed initiation. Initiation encompasses rapid changes in gene expression and phenotype that render the cells responsive to cytokines and other local stimuli. Cellular responses following initiation are termed perpetuation, which encompasses those cellular events that amplify the activated phenotype through enhanced growth factor expression and responsiveness. Multiple cells and cytokines play a part in the regulation of HSC activation. HSC activation consists of discrete phenotype responses, mainly proliferation, contractility, fibrogenesis, matrix degradation, chemotaxis and retinoid loss. Currently, antifibrotic therapeutic strategies include inhibition of HSC proliferation or stimulation of HSC apoptosis, downregulation of collagen production or promotion of its degradation, administration of cytokines, and infusion of mesenchymal stem cells. In this review, we summarize the latest advances in our understanding of the mechanisms of HSC activation and possible antifibrotic therapeutic strategies.

The role of urokinase in idiopathic pulmonary fibrosis and implication for therapy

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and frequently fatal form of interstitial lung disease for which there are no proven drug therapies. The pathogenesis of IPF is complex and the urokinase-type plasminogen activator (uPA)/plasminogen system participates in the repair process. The balance between the activating enzyme uPA, and its inhibitor PAI-1, is a critical determinant of the amount of scar development that follows.

OBJECTIVE

To address the role of urokinase in the pathogenesis of pulmonary fibrosis and its implications for therapy.

METHODS

We reviewed a spectrum of therapeutic strategies and focused on fibrinolytic and anticoagulant drugs for IPF patients.

RESULTS/CONCLUSION

There is currently a search for new pharmacotherapeutic agents that may modulate the fibrogenic pathways in IPF. Either blocking PAI-1 or using uPA itself may be a promising new therapeutic strategy.

Urokinase and its receptors in chronic kidney disease

This review focuses on the role of the serine protease urokinase-type plasminogen activator and its high affinity receptor uPAR/CD87 in chronic kidney disease (CKD) progression. An emerging theme is their organ- and site-specific effects. In addition to tubules, uPA is produced by macrophages and fibroblasts in CKD. By activating hepatocyte growth factor and degrading fibrinogen uPA may have anti-fibrotic effects. However renal fibrosis was similar between uPA wild-type and knockout mice in experimental CKD. The uPAR is expressed by renal parenchymal cells and inflammatory cells in a variety of kidney diseases. Such expression appears anti-fibrotic based on studies in uPAR-deficient mice. In CKD uPAR expression is associated with higher uPA activity but its most important effect appears to be due to effects on cell recruitment and migration that involve interactions with a variety of co-receptors and chemoattractant effects of soluble uPAR. Vitronectin and high molecular weight kininogen are alternate uPAR ligands, and receptors in addition to uPAR may also bind directly to uPA and activate cell signaling pathways.

Vascular endothelial growth factor attenuates hepatic sinusoidal capillarization in thioacetamide-induced cirrhotic rats

AIM: To investigate the effect of vascular endothelial growth factor (VEGF) transfection on hepatic sinusoidal capillarization.

METHODS: Enhanced green fluorescent protein (EGFP)/VEGF transfection was confirmed by immunofluorescence microscopy and immunohistoche-mistry both in primary hepatocytes and in normal liver. Cirrhotic rats were generated by thioacetamide (TAA) administration and then divided into a treatment group, which received injections of 400 &mgr;g of plasmid DNA encoding an EGFP-VEGF fusion protein, and a blank group, which received an equal amount of normal saline through the portal vein. The portal vein pressure was measured in the normal and cirrhotic state, in treated and blank groups. The average number of fenestrae per hepatic sinusoid was determined using transmission electron microscopy (TEM), while the relative abundance of VEGF transcripts was examined by Gene array.

RESULTS: Green fluorescent protein was observed in the cytoplasms of liver cells under immunofluorescence microscopy 24 h after transfection with EGFP/VEGF plasmid in vitro. Staining with polyclonal antibodies against VEGF illustrated that hepatocytes expressed immunodetectable VEGF both in vitro and in vitro. There were significant differences in the number of fenestrae and portal vein pressures between normal and cirrhotic rats (7.40 ± 1.71 vs 2.30 ± 1.16 and 9.32 ± 0.85 cmH₂O vs 17.92 ± 0.90 cmH₂O, P < 0.01), between cirrhotic and treated rats (2.30 ± 1.16 cmH₂O vs 4.60 ± 1.65 and 17.92 ± 0.90 cmH₂O vs 15.52 ± 0.93 cmH₂O, P < 0.05) and between the treatment group and the blank group (4.60 ± 1.65 cmH₂O vs 2.10 ± 1.10 cmH₂O and 15.52 ± 0.93 cmH₂O vs 17.26 ± 1.80 cmH₂O, P < 0.05). Gene-array analysis revealed that the relative abundance of transcripts of VEGF family members decreased in the cirrhotic state and increased after transfection.

CONCLUSION: Injection of a plasmid encoding VEGF through the portal vein is an effective method to induce the formation of fenestrae and decrease portal vein pressure in cirrhotic rats. Therefore, it may be a good choice for treating hepatic cirrhosis and portal hypertension.