Liver cirrhosis is reverted by urokinase-type plasminogen activator gene therapy

AdhMMP8 Vector Administration in Muscle: An Alternate Strategy to Regress Hepatic Fibrosis

The development of several vaccines against the SARS-CoV2 virus and their application in millions of people have shown efficacy and safety in the transfer of genes to muscle turning this tissue into a protein-producing factory. Established advanced liver fibrosis, is characterized by replacement of hepatic parenchyma by tissue scar, mostly collagen type I, with increased profibrogenic and proinflammatory molecules gene expression. Matrix metalloproteinase 8 (MMP-8) is an interstitial collagen-degrading proenzyme acting preferentially on collagen type I when activated. This study was carried out to elucidate the effect of an intramuscularly delivered adenoviral vector containing proMMP-8 gene cDNA (AdhMMP8) in male Wistar rats with experimental advanced liver fibrosis induced by thioacetamide. Therapeutic effects were monitored after 1, 2, or 3 weeks of a single dose (3 × 1011 vp/kg) of AdhMMP8. Circulating and liver concentration of MMP-8 protein remained constant; hepatic fibrosis decreased up to 48%; proinflammatory and profibrogenic genes expression diminished: TNF-α 2.28-fold, IL-1 1.95-fold, Col 1A1 4-fold, TGF-β1 3-fold and CTGF 2-fold; and antifibrogenic genes expression raised, MMP-9 2.8-fold and MMP-1 10-fold. Our data proposes that the administration of AdhMMP8 in muscle is safe and effective in achieving liver fibrosis regression at a comparable extent as when the adenoviral vector is delivered systemically to reach the liver, using a minimally invasive procedure.

Gene Therapy for Acquired and Genetic Cholestasis

Cholestatic diseases can be caused by the dysfunction of transporters involved in hepatobiliary circulation. Although pharmacological treatments constitute the current standard of care for these diseases, none are curative, with liver transplantation being the only long-term solution for severe cholestasis, albeit with many disadvantages. Liver-directed gene therapy has shown promising results in clinical trials for genetic diseases, and it could constitute a potential new therapeutic approach for cholestatic diseases. Many preclinical gene therapy studies have shown positive results in animal models of both acquired and genetic cholestasis. The delivery of genes that reduce apoptosis or fibrosis or improve bile flow has shown therapeutic effects in rodents in which cholestasis was induced by drugs or bile duct ligation. Most studies targeting inherited cholestasis, such as progressive familial intrahepatic cholestasis (PFIC), have focused on supplementing a correct version of a mutated gene to the liver using viral or non-viral vectors in order to achieve expression of the therapeutic protein. These strategies have generated promising results in treating PFIC3 in mouse models of the disease. However, important challenges remain in translating this therapy to the clinic, as well as in developing gene therapy strategies for other types of acquired and genetic cholestasis.

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.

Association between immunologic markers and cirrhosis in individuals with chronic hepatitis B

Host immune response and chronic inflammation associated with chronic hepatitis B virus (HBV) infection play a key role in the pathogenesis of liver diseases such as cirrhosis and hepatocellular carcinoma (HCC). We sampled 175 HCC, 117 cirrhotic and 165 non-cirrhotic controls from a prospective cohort study of chronically HBV-infected individuals. Multivariable polytomous logistic regression and canonical discriminant analysis (CDA) were used to compare baseline plasma levels for 102 markers in individuals who developed cirrhosis vs. controls and those who developed HCC vs. cirrhosis. Leave-one-out cross validation was used to generate receiver operating characteristic curves to compare the predictive ability of marker groups. After multivariable adjustment, HGF (Q4v1OR: 3.74; p-trend = 0.0001), SLAMF1 (Q4v1OR: 4.07; p-trend = 0.0001), CSF1 (Q4v1OR: 3.00; p-trend = 0.002), uPA (Q4v1OR: 3.36; p-trend = 0.002), IL-8 (Q4v1OR: 2.83; p-trend = 0.004), and OPG (Q4v1OR: 2.44; p-trend = 0.005) were all found to be associated with cirrhosis development compared to controls; these markers predicted cirrhosis with 69% accuracy. CDA analysis identified a nine marker model capable of predicting cirrhosis development with 79% accuracy. No markers were significantly different between HCC and cirrhotic participants. In this study, we assessed immunologic markers in relation to liver disease in chronically-HBV infected individuals. While validation in required, these findings highlight the importance of immunologic processes in HBV-related cirrhosis.

Fibrosis regression is induced by AdhMMP8 in a murine model of chronic kidney injury

Adenoviral vector AdhMMP8 (human Metalloproteinase-8 cDNA) administration has been proven beneficial in various experimental models of liver injury improving liver function and decreasing fibrosis. In this study, we evaluated the potential therapeutic AdhMMP8 effect in a chronic kidney damage experimental model. Chronic injury was induced by orogastric adenine administration (100mg/kg/day) to Wistar rats for 4 weeks. AdhMMP8 (3x1011vp/kg) was administrated in renal vein during an induced-ligation-ischemic period to facilitate kidney transduction causing no-additional kidney injury as determined by histology and serum creatinine. Animals were sacrificed at 7- and 14-days post-Ad injection. Fibrosis, histopathological features, serum creatinine (sCr), BUN, and renal mRNA expression of αSMA, Col-1α, TGF-β1, CTGF, BMP7, IL-1, TNFα, VEGF and PAX2 were analyzed. Interestingly, AdhMMP8 administration resulted in cognate human MMP8 protein detection in both kidneys, whereas hMMP8 mRNA was detected only in the left kidney. AdhMMP8 significantly reduced kidney tubule-interstitial fibrosis and glomerulosclerosis. Also, tubular atrophy and interstitial inflammation were clearly decreased rendering improved histopathology, and down regulation of profibrogenic genes expression. Functionally, sCr and BUN were positively modified. The results showed that AdhMMP8 decreased renal fibrosis, suggesting that MMP8 could be a possible therapeutic candidate for kidney fibrosis treatment.

Efficient drug and gene delivery to liver fibrosis: rationale, recent advances, and perspectives

Liver fibrosis results from chronic damages together with an accumulation of extracellular matrix, and no specific medical therapy is approved for that until now. Due to liver metabolic capacity for drugs, the fragility of drugs, and the presence of insurmountable physiological obstacles in the way of targeting, the development of efficient drug delivery systems for anti-fibrotics seems vital. We have explored articles with a different perspective on liver fibrosis over the two decades, then collected and summarized the information by providing corresponding in vitro and in vivo cases. We have discussed the mechanism of hepatic fibrogenesis with different ways of fibrosis induction in animals. Furthermore, the critical chemical and herbal anti-fibrotics, biological molecules such as micro-RNAs, siRNAs, and growth factors, which can affect cell division and differentiation, are mentioned. Likewise, drug and gene delivery and therapeutic systems on in vitro and in vivo models are summarized in the data tables. This review article enlightens recent advances in emerging drugs and nanocarriers and represents perspectives on targeting strategies employed in liver fibrosis treatment.

Adenovirus Biodistribution is Modified in Sensitive Animals Compared to Naïve Animals

Pre-existing immune response against adenovirus could diminish transgene expression efficiency when Ad is employed in humans as gene therapy vector. We previously used Ad-hΔuPA (Recombinant adenovirus expressing human urokinase-type plasminogen activator) as antifibrotic gene therapy in cirrhosis models and demonstrated its effectiveness. As a further clinical approach, transient Cyclosporine A (CsA) immunosuppression was induced in cirrhotic animals to determine whether Ad-hΔuPA administration retained efficacy. Adenovirus sensitization was achieved by systemic administration of non-therapeutic Ad-βGal (Recombinant adenovirus expressing beta-galactosidase) after 4 weeks of intraperitoneal carbon tetrachloride (CCl₄) regimen. Cirrhosis induction continued up to 8 weeks. At the end of CCl₄ intoxication, immunosuppression was achieved with three CsA doses (40 mg/kg) as follows: 24 h before administration of Ad-hΔuPA, at the moment of Ad-hΔuPA injection and finally, 24 h after Ad-hΔuPA inoculation. At 2 and 72 h after Ad-hΔuPA injection, animals were sacrificed. Liver, spleen, lung, kidney, heart, brain, and testis were analyzed for Ad-biodistribution and transgene expression. In naïve animals, Ad-hΔuPA genomes prevailed in liver and spleen, while Ad-sensitized rats showed Ad genomes also in their kidney and heart. Cirrhosis and Ad preimmunization status notably diminished transgene liver expression compared to healthy livers. CsA immunosuppression in cirrhotic animals has no effect on Ad-hΔuPA biodistribution, but increments survival.

Interferon-α Silencing by Small Interference RNA Increases Adenovirus Transduction and Transgene Expression in Huh7 Cells

Adenoviruses are the most common vectors used in clinical trials of gene therapy. In 2017, 21.2% of clinical trials used rAds as vectors. Systemic administration of rAds results in high tropism in the liver. Interferon types α and β are the major antiviral cytokines which orchestrate the host's immune response against rAd, limiting therapeutic gene expression and preventing subsequent vector administration. siRNA is small double-strand RNAs that temporally inhibit the expression of a specific gene. The aim is to evaluate the effect of IFN-α blocking by a specific siRNA on Ad-GFP transduction and on transgene expression in Huh7 cells in culture. Huh7 cells were cultured in DMEM and transfected with 70 nM of siRNA-IFN-α. Six hours later, the cells were exposed to 1 × 10⁹ vp/ml of rAd-GFP for 24 h. Expression of IFN-α, TNF-α and the PKR gene was determined by RT-qPCR. Percentage of transduction was analyzed by flow cytometry and by qPCR. GFP expression was determined by western blot. 70 nM of siRNA-IFN-α inhibited 96% of IFN-α and 65% of TNF-α gene expression compared to an irrelevant siRNA. Percentage of transduction and transgene expression increased in these cells compared to an irrelevant siRNA. Inhibition of IFN-α expression by siRNA-IFN-α enabled a higher level of transduction and transgene expression GFP, highlighting the role of IFN-α in the elimination of adenovirus in transduced cells and thus suggesting that its inhibition could be an important strategy for gene therapy in clinical trials using adenovirus as a vector directed to liver diseases.

Current Perspectives Regarding Stem Cell-Based Therapy for Liver Cirrhosis

Liver cirrhosis is a major cause of mortality and a common end of various progressive liver diseases. Since the effective treatment is currently limited to liver transplantation, stem cell-based therapy as an alternative has attracted interest due to promising results from preclinical and clinical studies. However, there is still much to be understood regarding the precise mechanisms of action. A number of stem cells from different origins have been employed for hepatic regeneration with different degrees of success. The present review presents a synopsis of stem cell research for the treatment of patients with liver cirrhosis according to the stem cell type. Clinical trials to date are summarized briefly. Finally, issues to be resolved and future perspectives are discussed with regard to clinical applications.

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.

New gene therapy strategies for hepatic fibrosis

The liver is the largest internal organ of the body, which may suffer acute or chronic injury induced by many factors, leading to cirrhosis and hepatocarcinoma. Cirrhosis is the irreversible end result of fibrous scarring and hepatocellular regeneration, characterized by diffuse disorganization of the normal hepatic structure, regenerative nodules and fibrotic tissue. Cirrhosis is associated with a high co-morbidity and mortality without effective treatment, and much research has been aimed at developing new therapeutic strategies to guarantee recovery. Liver-based gene therapy has been used to downregulate specific genes, to block the expression of deleterious genes, to delivery therapeutic genes, to prevent allograft rejection and to augment liver regeneration. Viral and non-viral vectors have been used, with viral vectors proving to be more efficient. This review provides an overview of the main strategies used in liver-gene therapy represented by non-viral vectors, viral vectors, novel administration methods like hydrodynamic injection, hybrids of two viral vectors and blocking molecules, with the hope of translating findings from the laboratory to the patient´s bed-side.

Use of mesenchymal stem cells to treat liver fibrosis: Current situation and future prospects

Progressive liver fibrosis is a major health issue for which no effective treatment is available, leading to cirrhosis and orthotopic liver transplantation. However, organ shortage is a reality. Hence, there is an urgent need to find alternative therapeutic strategies. Cell-based therapy using mesenchymal stem cells (MSCs) may represent an attractive therapeutic option, based on their immunomodulatory properties, their potential to differentiate into hepatocytes, allowing the replacement of damaged hepatocytes, their potential to promote residual hepatocytes regeneration and their capacity to inhibit hepatic stellate cell activation or induce their apoptosis, particularly via paracrine mechanisms. The current review will highlight recent findings regarding the input of MSC-based therapy for the treatment of liver fibrosis, from in vitro studies to pre-clinical and clinical trials. Several studies have shown the ability of MSCs to reduce liver fibrosis and improve liver function. However, despite these promising results, some limitations need to be considered. Future prospects will also be discussed in this review.

Efficient hepatic delivery of drugs: novel strategies and their significance

Liver is a vital organ responsible for plethora of functions including detoxification, protein synthesis, and the production of biochemicals necessary for the sustenance of life. Therefore, patients with chronic liver diseases such as viral hepatitis, liver cirrhosis, and hepatocellular carcinoma need immediate attention to sustain life and as a result are often exposed to the prolonged treatment with drugs/herbal medications. Lack of site-specific delivery of these medications to the hepatocytes/nonparenchymal cells and adverse effects associated with their off-target interactions limit their continuous use. This calls for the development and fabrication of targeted delivery systems which can deliver the drug payload at the desired site of action for defined period of time. The primary aim of drug targeting is to manipulate the whole body distribution of drugs, that is, to prevent distribution to non-target cells and concomitantly increase the drug concentration at the targeted site. Carrier molecules are designed for their selective cellular uptake, taking advantage of specific receptors or binding sites present on the surface membrane of the target cell. In this review, various aspects of liver targeting of drug molecules and herbal medications have been discussed which elucidate the importance of delivering the drugs/herbal medications at their desired site of action.

Coagulation and coagulation signalling in fibrosis

Following tissue injury, a complex and coordinated wound healing response comprising coagulation, inflammation, fibroproliferation and tissue remodelling has evolved to nullify the impact of the original insult and reinstate the normal physiological function of the affected organ. Tissue fibrosis is thought to result from a dysregulated wound healing response as a result of continual local injury or impaired control mechanisms. Although the initial insult is highly variable for different organs, in most cases, uncontrolled or sustained activation of mesenchymal cells into highly synthetic myofibroblasts leads to the excessive deposition of extracellular matrix proteins and eventually loss of tissue function. Coagulation was originally thought to be an acute and transient response to tissue injury, responsible primarily for promoting haemostasis by initiating the formation of fibrin plugs to enmesh activated platelets within the walls of damaged blood vessels. However, the last 20years has seen a major re-evaluation of the role of the coagulation cascade following tissue injury and there is now mounting evidence that coagulation plays a critical role in orchestrating subsequent inflammatory and fibroproliferative responses during normal wound healing, as well as in a range of pathological contexts across all major organ systems. This review summarises our current understanding of the role of coagulation and coagulation initiated signalling in the response to tissue injury, as well as the contribution of uncontrolled coagulation to fibrosis of the lung, liver, kidney and heart. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Quercetin improves hepatic fibrosis reducing hepatic stellate cells and regulating pro-fibrogenic/anti-fibrogenic molecules balance

BACKGROUND AND AIM

Development of hepatic cirrhosis involves oxidative stress, inflammation, hepatic stellate cells (HSC)s activation and fibrosis. On the other hand, quercetin, a natural flavonoid is a potent antioxidant and activator of superoxide dismutase and catalase. The aim was to determinate the effect of quercetin on HSCs and development of hepatic fibrosis.

METHODS

Wistar male rats were chronically intoxicated with CCl(4) for 8 weeks and concomitantly treated with 100 mg/kg per day of quercetin. Oxidative state, inflammation and fibrosis were evaluated. Effect of quercetin on apoptosis of HSC was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling reaction.

RESULTS

Sixty percent of reduction in fibrosis index was observed with quercetin treatment compared with control animals. Considerable reduction on hepatic enzymes was detected in the quercetin group. Expression of pro-fibrotic genes (transforming growth factor-β [TGF-β], Collagen 1α [Col-1α] and connective tissue growth factor [CTGF]) were decreased by quercetin. Quercetin increased gene expression and functional activity of antioxidant enzymes superoxide dismutase and catalase. Inflammatory index was highly reduced as determined by H-E staining and pro-inflammatory cytokines expression and nuclear factor-κB activation were also inhibited. A significant reduction of 65% on activated HSC number was detected when rats were treated with quercetin. Quercetin also induced activation of matrix metalloproteinases MMP2 and MMP9 contributing to decreased index of fibrosis.

CONCLUSIONS

Treatment with quercetin reduces oxidation and inflammation and also prevents liver fibrosis, through induction of HSC apoptosis and activation of MMPs.

Copper-induced hepatitis: the COMMD1 deficient dog as a translational animal model for human chronic hepatitis

Chronic inflammatory liver disease regardless of aetiology leads to failing regeneration and fibrosis, ending in cirrhosis. Both in man and in animals this worldwide health problem has no definitive cure. Chronic liver injury causes hepatic stellate cells to proliferate and differentiate into matrix-producing cells. New therapeutic options will be developed upon detailed understanding of the molecular mechanisms driving liver fibrosis. This may lead to new anti-fibrotic therapies which need to be tested in suitable models before application in the veterinary and human clinic. On the other side, to restore the failing regenerative capacity of the diseased liver cells, adult progenitor cells are of interest, as an alternative to whole organ transplantation. In order to find the most suitable large animal model it is important to recognise that the typical histopathological reaction pattern of the liver can differ between mammalian species. It is therefore imperative that specialists in veterinary internal medicine and pathology, being familiar with the diseases and pathologies of the liver in different animal species, are teaming-up in finding the best models for veterinary and human liver diseases. Several large animal models have been mentioned, like pigs, sheep, and dogs. Based on the observations that man and dog share the same hepatopathies and have identical clinical, pathological and pathogenetic reaction patterns during the development of liver disease, the dog seems to be a properly suited species to test new therapeutic strategies for pets and their best friends.

Production of first generation adenoviral vectors for preclinical protocols: amplification, purification and functional titration

Gene therapy represents a promising approach in the treatment of several diseases. Currently, the ideal vector has yet to be designed; though, adenoviral vectors (Ad-v) have provided the most utilized tool for gene transfer due principally to their simple production, among other specific characteristics. Ad-v viability represents a critical variable that may be affected by storage or shipping conditions and therefore it is advisable to be assessed previously to protocol performance. The present work is unique in this matter, as the complete detailed process to obtain Ad-v of preclinical grade is explained. Amplification in permissive HEK-293 cells, purification in CsCl gradients in a period of 10 h, spectrophotometric titration of viral particles (VP) and titration of infectious units (IU), yielding batches of AdβGal, AdGFP, AdHuPA and AdMMP8, of approximately 10¹³-10¹⁴ VP and 10¹²-10¹³ IU were carried out. In vivo functionality of therapeutic AdHuPA and AdMMP8 was evidenced in rats presenting CCl₄-induced fibrosis, as more than 60% of fibrosis was eliminated in livers after systemic delivery through iliac vein in comparison with irrelevant AdβGal. Time required to accomplish the whole Ad-v production steps, including IU titration was 20 to 30 days. We conclude that production of Ad-v following standard operating procedures assuring vector functionality and the possibility to effectively evaluate experimental gene therapy results, leaving aside the use of high-cost commercial kits or sophisticated instrumentation, can be performed in a conventional laboratory of cell culture.

Alcoholic liver disease and the potential role of plasminogen activator inhibitor-1 and fibrin metabolism

Plasminogen activator inhibitor-1 (PAI-1) is a major player in fibrinolysis due to its classical role of inhibiting plasminogen activators. Although increased fibrinolysis is common in alcoholic cirrhosis, decreased fibrinolysis (driven mostly by elevated levels of PAI-1) is common during the development of alcoholic liver disease (ALD). However, whether or not PAI-1 plays a causal role in the development of early ALD was unclear. Recent studies in experimental models have suggested that PAI-1 may contribute to the development of early (steatosis), intermediate (steatohepatitis) and late (fibrosis) stages of ALD. For example, fatty liver owing to both acute and chronic ethanol was blunted by the genetic inhibition of PAI-1. This effect of targeting PAI-1 appears to be mediated, at least in part, by an increase in very low-density lipoprotein (VLDL) synthesis in the genetic absence of this acute phase protein. Results from a two-hit model employing ethanol and lipopolysaccharide administration suggest that PAI-1 plays a critical role in hepatic inflammation, most likely due to its ability to cause fibrin accumulation, which subsequently sensitizes the liver to ensuing damaging insults. Lastly, the role of PAI-1 in hepatic fibrosis is less clear and appears that PAI-1 may serve a dual role in this pathological change, both protective (enhancing regeneration) and damaging (blocking matrix degradation). In summary, results from these studies suggest that PAI-1 may play multiple roles in the various stages of ALD, both protective and damaging. The latter effect is mediated by its influence on steatosis (i.e. decreasing VLDL synthesis), inflammation (i.e. impairing fibrinolysis) and fibrosis (i.e. blunting matrix degradation), whereas the former is mediated by maintaining hepatocyte division after an injury.

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.

Texture analysis of liver fibrosis microscopic images: a study on the effect of biomarkers

Chronic hepatic injury results in liver fibrosis with eventual progression to irreversible cirrhosis. Liver fibrogenesis involves the activation of the quiescent hepatic stellate cell into an activated myofibroblast that is characterized by α-smooth muscle actin (α-SMA) expression and the production of collagens (types I and III). In the present study, rats were randomly divided into three groups: (i) control group, where rats were only treated with a vehicle; (ii) fibrosis group, where rats were treated with carbon tetrachloride (CCl(4)) to induce liver fibrosis; and (iii) silymarin group, where rats were protected with silymarin during CCl(4) treatment. Rats were sacrificed and sections of liver tissue were counterstained with hematoxylin and eosin and Masson's trichrome. Other sections were immunostained using collagens and α-SMA primary antibodies. Fibrosis was confirmed using serum marker measurements. Microscopic images of the stained sections were acquired and digitized. The Biomarker Index of Fibrosis (BIF) was calculated from the images by quantifying the percentage of stained fibers. Statistical methods of texture analysis (TA), namely co-occurrence and run-length matrices, were applied on the digital images followed by classification using agglomerative hierarchical clustering and linear discriminant analysis with cross validation. TA applied on different biomarkers was successful in discriminating between the groups, showing 100% sensitivity and specificity for classification between the control and fibrosis groups using any biomarker. Some classification attempts showed dependence on the biomarker used, especially for classification between the silymarin and fibrosis groups, which showed optimal results using Masson's trichrome. TA results were consistent with both BIF and serum marker measurements.

Curcumin down-regulates PAI-1 expression but up-regulates u-PA expression in carbon tetrachloride-induced hepatic fibrosis in rats

AIM: To investigate the effects of curcumin on the expression of plasminogen activator inhibitor-1 (PAI-1) and urokinase-type plasminogen activator (u-PA) in carbon tetrachloride-induced hepatic fibrosis in rats.

METHODS: One hundred male Sprague-Dawley rats were randomly divided into five groups: normal group, model group, low-, medium- and high-dose curcumin group. Except the normal group, the rats of the other groups were intraperitoneally injected with carbon tetrachloride for 6 wk to induce liver fibrosis. The rats of the low-, medium- and high-dose curcumin groups were administrated different doses of curcumin. On days 4, 7, 21 and 42 after treatment, five rats randomly selected from each group were sacrificed to take liver specimens for pathological examination (HE). The expression of PAI-1 and u-PA in hepatic fibrosis was detected by immunohistochemistry.

RESULTS: The expression levels of PAI-1 and u-PA were much lower in the normal group than in the model group. Compared to the model group, PAI-1 expression was significantly down-regulated (42 d: 5.60 ± 1.673, 3.40 ± 1.673, 2.40 ± 1.140 vs 8.80 ± 2.168, all P < 0.05) and u-PA expression was significantly up-regulated (42 d: 6.00 ± 1.414, 9.20 ± 1.643, 9.80 ± 2.049 vs 4.20 ± 1.095, P < 0.05) in the low-, medium- and high-dose curcumin groups. Curcumin treatment altered the expression of PAI-1 and u-PA in a dose- and time-dependent manner.

CONCLUSION: Curcumin exerts anti-fibrotic effects possibly by decreasing the expression of PAI-1 and increasing the expression of u-PA.

Macrophages: master regulators of inflammation and fibrosis

Macrophages are found in close proximity with collagen-producing myofibroblasts and indisputably play a key role in fibrosis. They produce profibrotic mediators that directly activate fibroblasts, including transforming growth factor-beta1 and platelet-derived growth factor, and control extracellular matrix turnover by regulating the balance of various matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases. Macrophages also regulate fibrogenesis by secreting chemokines that recruit fibroblasts and other inflammatory cells. With their potential to act in both a pro- and antifibrotic capacity, as well as their ability to regulate the activation of resident and recruited myofibroblasts, macrophages and the factors they express are integrated into all stages of the fibrotic process. These various, and sometimes opposing, functions may be performed by distinct macrophage subpopulations, the identification of which is a growing focus of fibrosis research. Although collagen-secreting myofibroblasts once were thought of as the master "producers" of fibrosis, this review will illustrate how macrophages function as the master "regulators" of fibrosis.

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.

Transplanted endothelial progenitor cells ameliorate carbon tetrachloride-induced liver cirrhosis in rats

Cirrhosis is the most common end stage of liver diseases, and there are no effective treatment methods. Here we evaluated the effect of endothelial progenitor cell (EPC) transplantation from rat bone marrow (BM) on the development of cirrhosis induced by carbon tetrachloride (CCl(4)). Ex vivo generated, characterized, and cultivated rat BM-derived EPCs were identified by their vasculogenic properties in vitro. EPCs from male rats were transplanted into female rats via the intraportal vein 12 weeks after they had been challenged with CCl(4), and the rats were killed 16 weeks later. The control rats received only a saline infusion. The fibrosis index and donor cell engraftment were assessed after EPC transplantation. After transplantation via the portal vein, PKH26 labeling, polymerase chain reaction, and in situ hybridization analysis revealed that the donor EPCs had adhered to the vasolateral surfaces of blood vessels and established in the liver. EPCs reduced the expression of alpha-smooth muscle actin, collagen III, and transforming growth factor beta (P < 0.05) as well as levels of aspartate aminotransferase, alanine aminotransferase, and total bilirubin in the serum (P < 0.05), but at the same time they increased the levels of albumin and Ki67. CCl(4) treatment increased the international prothrombin ratio (P < 0.05) and reduced albumin levels, whereas EPCs restored these parameters to normal levels. These results suggest that EPC transplantation could play a role in regulating hepatocyte regeneration and ameliorating established liver cirrhosis.

Active matrix metalloproteinase-2 promotes apoptosis of hepatic stellate cells via the cleavage of cellular N-cadherin

BACKGROUND AND AIMS

Hepatic stellate cells (HSC) are known to synthesise excess matrix that characterises liver fibrosis and cirrhosis. Activated HSC express the matrix-degrading matrix metalloproteinase enzymes (MMPs) and their tissue inhibitors (TIMPs). During spontaneous recovery from experimental liver fibrosis, the expression of TIMP-1 declines and hepatic collagenolytic activity increases. This is accompanied by HSC apoptosis. In this study, we examine a potential mechanism whereby MMP activity might induce HSC apoptosis by cleaving N-cadherin at the cell surface.

RESULTS

N-cadherin expression was upregulated in human HSC during activation in culture. Addition of function-blocking antibodies or a peptide targeting the extracellular domain of N-cadherin, to cultured HSC, promoted apoptosis. During apoptosis, there was cleavage of N-cadherin into 20-100 kDa fragments. MMP-2 became activated early during HSC apoptosis and directly cleaved N-cadherin in vitro. Addition of activated MMP-2 to HSCs in culture resulted in enhanced apoptosis and loss of N-cadherin.

CONCLUSIONS

Together, these studies identify a role for both N-cadherin and MMP-2 in mediating HSC apoptosis, where N-cadherin works to provide a cell survival stimulus and MMP-2 promotes HSC apoptosis concomitant with N-cadherin degradation.

Altered factor VII activating protease expression in murine hepatic fibrosis and its influence on hepatic stellate cells

BACKGROUND

Platelet-derived growth factor-BB (PDGF-BB) is a profibrotic factor in liver fibrosis through its ability to stimulate hepatic stellate cells (HSC). The liver-derived serine protease factor VII activating protease (FSAP) regulates the activities of PDGF-BB in a cell-specific manner.

AIMS

Our aim was to determine the influence of FSAP on the activation of HSC and to analyse the regulation of FSAP in hepatic fibrogenesis.

METHODS

The effect of FSAP on PDGF-stimulated p42/p44 mitogen-activated protein kinase (MAPK) activation in primary rat HSC was determined by Western blotting. Migration and proliferation of HSC was evaluated in Boyden chamber experiments and (3)H-thymidine incorporation assays respectively. Expression of FSAP was analysed in a CCl(4) mouse model of liver fibrosis by Western blot, quantitative real-time polymerase chain reaction and immunohistochemistry.

RESULTS

FSAP inhibited PDGF-BB-stimulated p42/p44 MAPK phosphorylation, proliferation and migration of HSC. FSAP mRNA expression level was increased 3 h after CCl(4) application and decreased after 18 h and, in established fibrosis, after chronic CCl(4) administration. In parallel, there was a decrease in the circulating FSAP protein in chronic fibrosis. Concurrently, the homogenous hepatic expression pattern of FSAP was disturbed. Immunohistochemistry revealed a decrease of FSAP in hepatocytes in inflammatory and fibrotic lesions.

CONCLUSIONS

Our results demonstrate an inhibitory effect of FSAP on PDGF-mediated activation of HSC. In addition, FSAP expression is transiently increased in acute-phase reaction but decreased during chronic fibrogenesis, which in turn may influence PDGF-BB availability and myofibroblast activity.

Adenoviral delivery of dominant-negative transforming growth factor beta type II receptor up-regulates transcriptional repressor SKI-like oncogene, decreases matrix metalloproteinase 2 in hepatic stellate cell and prevents liver fibrosis in rats

BACKGROUND

Dominant-negative transforming growth factor beta type II receptor (TbetaRIIDeltacyt) is a protein that blocks transforming growth factor (TGF-beta) signaling. Because the consequences of blocking TGF-beta have not been completely elucidated in liver fibrosis, we analysed the effects of adenoviral delivery of TbetaRIIDeltacyt on profibrogenic genes and matrix metalloproteinase (MMP) proteins, as well as on TGF-beta signal repressor SKI-like oncogene (SnoN), in cultured hepatic stellate cells (HSCs) and in a rat model of liver fibrosis.

METHODS

To induce liver fibrosis, rats were treated with thioacetamide for 7 weeks and administrated once with Ad-TbetaRIIDeltacyt or Ad-betagal through the iliac vein. Fibrosis was measured by morphometric analysis. We evaluated SnoN by western blot, immunocytochemistry and immunohistochemistry; MMP activity was determined by zymography and profibrogenic gene expression by the real-time reverse transcriptase-polymerase chain reaction in cultured HSCs and liver tissue.

RESULTS

Profibrogenic gene expression of collagen alpha1 (I), TGF-beta1, platelet-derived growth factor-B, plasminogen activator inhibitor (PAI)-1, tissue inhibitor of matrix metalloproteinase-1 and MMP-2 was down-regulated; whereas MMP-3 was over-expressed in response to Ad-TbetaRIIDeltacyt in HSCs. Moreover, zymography assays corroborated MMP-2 and MMP-3 changes in activity. Surprisingly, anti-TGF-beta molecular intervention increased nuclear SnoN in HSCs. In vivo, Ad-TbetaRIIDeltacyt reduced liver fibrosis, increased nuclear SnoN in sinusoidal cells, and also produced significant suppression in collagen alpha1 (I), TGF-beta1, PAI-1, MMP-2 and over-expression in MMP-3 in thioacetamide-intoxicated animals.

CONCLUSIONS

The results obtained in the present study suggest that the molecular mechanism for the blocking effects of Ad-TbetaRIIDeltacyt in TGF-beta signaling acts via up-regulation of the transcriptional repressor SnoN, which antagonizes TGF-beta signaling (TGF-beta/Smad-pathway inhibitor). Consequently, profibrogenic genes are down-regulated.

Progress toward liver-based gene therapy

The liver is involved in the synthesis of serum proteins, regulation of metabolism and maintenance of homeostasis and provides a variety of opportunities for gene therapy. The enriched vasculature and blood circulation, fenestrated endothelium, abundant receptors on the plasma membranes of the liver cells, and effective transcription and translation machineries in the hepatocytes are some unique features that have been explored for delivery, and functional analysis, of genetic sequences in the liver. Both viral and non-viral methods have been developed for effective gene delivery and liver-based gene therapy. This review describes the fundamentals of gene delivery, and the preclinical and clinical progress that has been made toward gene therapy using the liver as a target.

Expression profile of BRCA1 and BRCA2 genes in premenopausal Mexican women with breast cancer: clinical and immunohistochemical correlates

Low BRCA1 gene expression is associated with increased invasiveness and influences the response of breast carcinoma (BC) to chemotherapeutics. However, expression of BRCA1 and BRCA2 genes has not been completely characterized in premenopausal BC. We analyzed the clinical and immunohistochemical correlates of BRCA1 and BRCA2 expression in young BC women. We studied 62 women (mean age 38.8 years) who developed BC before the age of 45 years. BRCA1 and BRCA2 mRNA expression was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) and that of HER-2 and p53 proteins by immunohistochemistry. Body mass index (BMI) > or = 27 (52%) and a declared family history of BC (26%) were the main risk factors. Ductal infiltrative adenocarcinoma was found in 86% of the cases (tumor size >5 cm in 48%). Disease stages I-IV occurred in 2, 40, 55, and 3%, respectively (73% implicating lymph nodes). Women aged < or = 35 years (24%) had more family history of cervical cancer, stage III/IV disease, HER-2 positivity, and lower BRCA1 expression than older women (P < 0.05). BRCA1 and BRCA2 expression correlated in healthy, but not in tumor tissues (TT). Neither BRCA1 nor BRCA2 expression was associated with tumor histology, differentiation, nodal metastasis or p53 and HER-2 expression. After multivariate analysis, only disease stage explained BRCA1 mRNA levels in the lowest quartile. Premenopausal BC has aggressive clinical and molecular characteristics. Low BRCA1 mRNA expression is associated mainly with younger ages and advanced clinical stage of premenopausal BC. BRCA2 expression is not associated with disease severity in young BC women.

Animal models for target diseases in gene therapy--using DNA and siRNA delivery strategies

Nanoparticles, including lipopolyamines leading to lipoplexes, liposomes, and polyplexes are targeted drug carrier systems in the current search for a successful delivery system for polynucleic acids. This review is focused on the impact of gene and siRNA delivery for studies of efficacy, pharmacodynamics, and pharmacokinetics within the setting of the wide variety of in vivo animal models now used. This critical appraisal of the recent literature sets out the different models that are currently being investigated to bridge from studies in cell lines through towards clinical reality. Whilst many scientists will be familiar with rodent (murine, fecine, cricetine, and musteline) models, few probably think of fish as a clinically relevant animal model, but zebrafish, madake, and rainbow trout are all being used. Larger animal models include rabbit, cat, dog, and cow. Pig is used both for the prevention of foot-and-mouth disease and human diseases, sheep is a model for corneal transplantation, and the horse naturally develops arthritis. Non-human primate models (macaque, common marmoset, owl monkey) are used for preclinical gene vector safety and efficacy trials to bridge the gap prior to clinical studies. We aim for the safe development of clinically effective delivery systems for DNA and RNAi technologies.

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.

Targeting liver myofibroblasts: a novel approach in anti-fibrogenic therapy

Chronic liver disease results in a liver-scarring response termed fibrosis. Excessive scarring leads to cirrhosis, which is associated with high morbidity and mortality. The only treatment for liver cirrhosis is liver transplantation; therefore, much attention has been directed toward therapies that will slow or reverse fibrosis. Although anti-fibrogenic therapies have been shown to be effective in experimental animal models, licensed therapies have yet to emerge. A potential problem for any anti-fibrogenic therapy in the liver is the existence of the body’s major drug metabolising cell (the hepatocyte) adjacent to the primary fibrosis-causing cell, the myofibroblast. This article reviews the development of a human recombinant single-chain antibody (scAb) that binds to the surface of myofibroblasts. This antibody binds specifically to myofibroblasts in fibrotic mouse livers. When conjugated with a compound that stimulates myofibroblast apoptosis, the antibody directs the specific apoptosis of myofibroblasts with greater specificity and efficacy than the free compound. The antibody also reduces the adverse effect of liver macrophage apoptosis and—in contrast to the free compound—reversed fibrosis in the sustained injury model used. These data suggest that specifically stimulating the apoptosis of liver myofibroblasts using a targeting antibody has potential in the treatment of liver fibrosis.

Potent antioxidant role of pirfenidone in experimental cirrhosis

Three important features must be considered when proposing therapeutic strategies in liver cirrhosis: inflammation, oxidative stress and fibrogenesis. Pirfenidone is a synthetic molecule which oxidative action has not been tested in cirrhosis. Cirrhosis was induced in rats by ligation of the common bile duct or carbon tetrachloride (CCl(4)) chronic intoxication and treated with pirfenidone or diphenyleneiodonium (a potent known antioxidant) for the last two weeks for bile duct ligation model or for the last three weeks for CCl(4) chronic intoxication. A 60% reduction in fibrosis index for bile duct ligation model and 42% for CCl(4) along with reduced inflammation was observed. Considerable reduction on hepatic enzymes and total and direct bilirubins were detected with pirfenidone in both models. Pirfenidone antioxidant capacity rendered a 28% and 30% reduction in nitrites and malonyldealdehide concentration in bile duct ligation and 52% and 38% in CCl(4). With respect to gene expression, fibrotic genes like transforming growth factor-beta (TGF-beta) and collagen Ialpha (Col-1alpha) were down-regulated by pirfenidone and increased expression of regenerative genes like hepatocyte growth factor (HGF) and c-met . Superoxide dismutase (SOD), catalase (CAT) and inducible nitric oxide synthase (iNOS) gene expression were importantly down-regulated where nuclear factor kappa B (NF-kappaB) binding activity also decreased with pirfenidone treatment. Also, SOD and CAT functional activity decreased after pirfenidone action. On the other hand, diphenyleneiodonium induced a drop in oxidative stress similar in extent to pirfenidone, but it was not as effective as pirfenidone in reducing fibrosis. In this work, we showed antioxidant properties of pirfenidone beyond its well-known antifibrotic effect. These features make pirfenidone an attractive drug for trying fibrotic diseases accompanied by oxidative stress processes.

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.

Bioconjugation of oligonucleotides for treating liver fibrosis

Liver fibrosis results from chronic liver injury due to hepatitis B and C, excessive alcohol ingestion, and metal ion overload. Fibrosis culminates in cirrhosis and results in liver failure. Therefore, a potent antifibrotic therapy is urgently needed to reverse scarring and eliminate progression to cirrhosis. Although activated hepatic stellate cells (HSCs) remain the principle cell type responsible for liver fibrosis, perivascular fibroblasts of portal and central veins as well as periductular fibroblasts are other sources of fibrogenic cells. This review will critically discuss various treatment strategies for liver fibrosis, including prevention of liver injury, reduction of inflammation, inhibition of HSC activation, degradation of scar matrix, and inhibition of aberrant collagen synthesis. Oligonucleotides (ODNs) are short, single-stranded nucleic acids, which disrupt expression of target protein by binding to complementary mRNA or forming triplex with genomic DNA. Triplex forming oligonucleotides (TFOs) provide an attractive strategy for treating liver fibrosis. A series of TFOs have been developed for inhibiting the transcription of alpha1(I) collagen gene, which opens a new area for antifibrotic drugs. There will be in-depth discussion on the use of TFOs and how different bioconjugation strategies can be utilized for their site-specific delivery to HSCs or hepatocytes for enhanced antifibrotic activities. Various insights developed in individual strategy and the need for multipronged approaches will also be discussed.

Emerging drugs for complications of end-stage liver disease

BACKGROUND

The prevalence of end-stage liver disease is rising rapidly and constitutes a major healthcare burden currently. Many cases are diagnosed at a later stage when liver transplantation is the only effective treatment option. There is thus an urgent need for novel treatments to reverse the earlier stages of cirrhosis as well as to treat the many associated life-threatening complications.

OBJECTIVES

To review the current drugs available for treating the complications of advanced liver disease. To address novel treatment strategies that are in development, with particular reference to the rapidly developing area of antifibrotic therapy. To assess how the obstacles that have so far impeded the development of effective new drugs for end-stage liver disease may be overcome in the future.

METHODS

The literature was reviewed to define current therapies and therapies in clinical trials. We used the current models of the molecular basis of liver fibrogenesis to determine potential new therapeutic targets for antifibrotic therapy.

CONCLUSIONS

Insights into the pathogenesis of liver injury and fibrosis have opened up new avenues for therapy and there are now candidates and targets with real potential for the development of a new generation of antifibrotic therapies.

New role of plasminogen activator inhibitor-1 in alcohol-induced liver injury

Plasminogen activator inhibitor-1 (PAI-1) is the main inhibitor of plasminogen activators, thereby playing a major role in fibrinolysis. Whereas hyperfibrinolysis is common in alcoholic cirrhosis, hypofibrinolysis (driven mostly by elevated levels of PAI-1) is common during the development of alcoholic liver disease (ALD). However, whether or not PAI-1 plays a causal role in the development of ALD has been unclear. The role of PAI-1 was therefore investigated in models of early (steatosis), intermediate (inflammation/necrosis) and late (fibrosis) stages of alcoholic liver disease. For example, hepatic steatosis caused by both acute and chronic ethanol was blunted by inhibiting PAI-1 activation. This effect of inhibiting PAI-1 appears to be mediated, at least in part, by an increase in very low-density lipoprotein (VLDL) synthesis in the absence of PAI-1. The results from that study also indicated that PAI-1 plays a critical role in both acute and chronic hepatic inflammation. Lastly, knocking out PAI-1 potently protected against experimental hepatic fibrosis; the mechanism of this protective effect appears to be mediated predominantly by extracellular matrix (ECM) resolution by matrix metalloproteases, which are indirectly inhibited by PAI-1. In summary, targeting PAI-1 protects against all three stages of ALD in model systems. The mechanisms by which PAI-1 contributes to these disease stages appear to not only involve the 'classical' function of PAI-1 (i.e. in mediating fibrinolysis), but also other functions of this protein. These data support a role of PAI-1 in the initiation and progression of ALD, and suggest that PAI-1 may be a useful target for clinical therapy to halt or blunt disease progression.

Transplantation of bone marrow-derived hepatocyte stem cells transduced with adenovirus-mediated IL-10 gene reverses liver fibrosis in rats

Bone marrow stem cells (BMSCs) transplantation alone may not be sufficient for treatment of liver fibrosis because of complicated histopathologic changes in the liver. Interleukin-10 (IL-10) is an anti-fibrosis cytokine. IL-10 gene transfer of beta2m(-)/Thy-1+ bone marrow-derived hepatocyte stem cells (BDHSCs) may be useful for treating liver fibrosis. To determine the effect of liver fibrosis in rats by transplanting BDHSCs transduced with adenovirus-mediated IL-10 gene (AdIL-10), rat BDHSCs were isolated by magnetic bead cell sorting, characterized for liver-associated phenotypes, transduced with AdIL-10, and transplanted into liver-fibrotic rats. We show that BDHSCs secreted high-level IL-10 and retained their albumin expression after AdIL-10 transfer in vitro. Intra-portal-infused BDHSCs were implanted into the liver 2 weeks after transplantation. Transplanting AdIL-10-transduced BDHSCs into liver-fibrotic rats downregulated inflammatory response, promoted liver regeneration, suppressed activation of hepatic stellate cells and improved liver histopathology and liver function. These findings demonstrated the potential utility of this novel combined strategy of IL-10 gene and BDHSCs for the treatment of liver fibrosis.

PDGF-receptor beta-targeted adenovirus redirects gene transfer from hepatocytes to activated stellate cells

Chronic liver damage may lead to liver fibrosis. In this process, hepatic activated stellate cells are the key players. Thus, activated stellate cells are attractive targets for antifibrotic gene therapy. Recombinant adenovirus is a promising vehicle for delivering therapeutic genes to liver cells. However, this vector has considerable tropism for hepatocytes and Kupffer cells. The aim of this study is therefore to retarget the adenovirus to the activated stellate cells while reducing its affinity for hepatocytes. We constructed a fusion protein with affinity for both the adenovirus and the platelet derived growth factor-receptor beta (PDGF-Rbeta). In contrast to other cells, the PDFG-Rbeta is highly expressed on activated stellate cells. The targeting moiety, the PDGF peptide CSRNLIDC, was cloned in front of the single-chain antibody fragment (S11) directed against the adenoviral knob. This fusion protein enhanced adenoviral gene transfer in both 3T3 fibroblasts and primary isolated activated rat stellate cells by 10-60-fold. A fusion protein with a scrambled PDGF peptide (CIDNLSRC) did not accomplish this effect. Importantly, the PDGF-Rbeta-retargeted adenovirus showed a 25-fold reduced tropism for primary rat hepatocytes. Our novel approach demonstrates that therapeutic genes can be selectively directed to stellate cells. This opens new possibilities for the treatment of liver fibrosis.

Gene expression profile analysis of the spontaneous reversal of rat hepatic fibrosis by cDNA microarray

Our aim was to gain insight into the gene expression profile during hepatic fibrosis autoreversal. Spontaneous recovery from hepatic fibrosis was created in SD rats by CCl(4) exposure for 8 weeks and then withdrawal for 6 weeks. Then differentially expressed genes during regression of fibrosis were analyzed using cDNA microarray. Results obtained were further subjected to hierarchical clustering and validated by semiquantitative RT-PCR. Expression of Mapk1 and Rps6ka1, which are critical members of the mitogen-activated protein kinase (MAPK) signaling pathway, was also investigated by Northern blot and immunohistochemistry. Microarray hybridization identified 254 genes differentially expressed throughout resolution of fibrosis. Being verified by RT-PCR, up- or down-regulated genes were classified into various groups according to clustering and function: (1) metabolic enzymes, (2) facilitated diffusion proteins/transporters/symporters, (3) gastrointestinal hormones/receptors, (4) lipoproteins/fatty acid binding proteins, (5) transcription factors/nuclear factors, and (6) the MAPK signaling pathway. The mRNA level of Mapk1 increased greatly as hepatic fibrosis reversed. Meanwhile Mapk1 and Rps6ka1 were proven to be expressed in hepatocytes and absent from mesenchymal cells. Six groups of genes exhibit a close relation to the recovery of CCl(4)-induced hepatic fibrosis. The MAPK signaling-dependent pathway, representing one of the gene groups, may contribute to the reversal of hepatic fibrosis.