Pentoxifylline inhibits growth and collagen synthesis of cultured human hepatic myofibroblast-like cells

Pentoxifylline Inhibits Epidural Fibrosis in Post-Laminectomy Rats

BACKGROUND

The aim of this experimental study was to investigate the effectiveness of intramuscular pentoxifylline in the prevention of postoperative fibrosis.

MATERIAL/METHODS

We divided 16 adult Wistar albino rats into 2 equal groups: treatment and control. Both groups underwent L1 vertebral total laminectomy to expose the dura. The intramuscular treatment group received pentoxifylline. Four weeks later, epidural fibrosis was studied in both groups using electron microscopy, light microscopy, histology, biochemistry, and macroscopy.

RESULTS

The evaluation of epidural fibrosis in the 2 groups according to macroscopic (p<0.01) assessment and light microscopy revealed that epidural scar tissue formation was lower in the treatment group compared to the control group (p<0.001) and the number of fibroblasts was also decreased significantly in the pentoxifylline-treated group (p<0.05). More immature fibers were demonstrated in the treatment group by electron microscopy in comparison with the control group. In biochemical analysis, a statistically significant decrease was detected in hydroxyproline, which indicates fibrosis and myeloperoxidase activity, and shows an inflammatory response (P<0.001).

CONCLUSIONS

Systemic pentoxifylline application prevents postoperative epidural fibrosis and adhesions with various mechanisms. Our study is the first to present evidence of experimental epidural fibrosis prevention with pentoxifylline.

The Effector Protein BPE005 from Brucella abortus Induces Collagen Deposition and Matrix Metalloproteinase 9 Downmodulation via Transforming Growth Factor β1 in Hepatic Stellate Cells

The liver is frequently affected in patients with active brucellosis. In the present study, we identified a virulence factor involved in the modulation of hepatic stellate cell function and consequent fibrosis during Brucella abortus infection. This study assessed the role of BPE005 protein from B. abortus in the fibrotic phenotype induced on hepatic stellate cells during B. abortus infection in vitro and in vivo. We demonstrated that the fibrotic phenotype induced by B. abortus on hepatic stellate (LX-2) cells was dependent on BPE005, a protein associated with the type IV secretion system (T4SS) VirB from B. abortus. Our results indicated that B. abortus inhibits matrix metalloproteinase 9 (MMP-9) secretion through the activity of the BPE005-secreted protein and induces concomitant collagen deposition by LX-2 cells. BPE005 is a small protein containing a cyclic nucleotide monophosphate binding domain (cNMP) that modulates the LX-2 cell phenotype through a mechanism that is dependent on the cyclic AMP (cAMP)/protein kinase A (PKA) signaling pathway. Altogether, these results indicate that B. abortus tilts LX-2 cells to a profibrogenic phenotype employing a functional T4SS and the secreted BPE005 protein through a mechanism that involves the cAMP and PKA signaling pathway.

Comparative effectiveness of pharmacological interventions for nonalcoholic steatohepatitis: A systematic review and network meta-analysis

We performed a Bayesian network meta-analysis combining direct and indirect treatment comparisons to assess the comparative effectiveness of pharmacological agents for the treatment of nonalcoholic steatohepatitis (NASH). Through systematic literature review, we identified nine randomized, controlled trials (RCTs) including 964 patients with biopsy-proven NASH, comparing vitamin E, thiazolidinediones (TZDs), pentoxifylline, or obeticholic acid to one another or placebo. The primary outcome was improvement in fibrosis stage; secondary outcomes were improvement in ballooning degeneration, lobular inflammation, and steatosis. We reported relative risks (RRs) and 95% confidence intervals (CIs) from direct meta-analysis and 95% credible intervals (CrIs) from Bayesian network meta-analysis, and used Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria to appraise quality of evidence. Moderate-quality evidence supports the use of pentoxifylline (RR, 0.26; 95% CrI: 0.05-1.00) and obeticholic acid (RR, 0.81; 95% CI: 0.70-0.95) over placebo in improving fibrosis. High-quality evidence supports the effect of vitamin E, TZDs, and obeticholic acid over placebo in improving ballooning degeneration. All four interventions seemed to have at least moderate-quality evidence over placebo to improve steatosis. Moderate-quality evidence supports that TZDs, pentoxifylline, and obeticholic acid decrease lobular inflammation. All the head-to-head comparisons were supported by very-low-quality evidence except for superiority of TZDs over vitamin E on improving steatosis and lobular inflammation, which had moderate-quality evidence.

CONCLUSIONS

Based on direct and network meta-analysis, pentoxifylline and obeticholic acid improve fibrosis, and vitamin E, TZDs, and obeticholic acid improve ballooning degeneration in patients with NASH. Future comparative trials of combination therapies targeting distinct histological features are warranted.

Pentoxifylline immunomodulation in the treatment of experimental chronic pulmonary paracoccidioidomycosis

Background

Pentoxifylline (PTX) is a methylxanthine compound with immunomodulatory and antifibrotic properties. The simultaneous use of PTX and antifungal therapy (itraconazole) has previously been evaluated in an experimental model of pulmonary paracoccidioidomycosis (PCM), a systemic fungal disease caused by the fungus Paracoccidioides brasiliensis (Pb) and characterized by chronic inflammation and lung fibrosis that appears even after a successful course of antifungal therapy. The results revealed prompt and statistically significant reductions in inflammation and fibrosis when compared to itraconazole alone. However, the effect of monotherapy with PTX on the host response to PCM has not been well-documented. Our aim was to determine the effect of PTX on the course of pulmonary lesions and on the local immune response.

Results

At the middle and end of treatment, the Pb-infected-PTX-treated mice exhibited significant reductions in lung density compared to the Pb-infected-non-treated mice as assessed by the quantification of Hounsfield units on high-resolution computed tomography (HRCT) (p <0.05 by Kruskal-Wallis test); additionally, at the end of therapy, the lung areas involved in the inflammatory reactions were only 3 vs. 22 %, respectively, by histomorphometry (p <0.05 by Mann–Whitney test), and this reduction was associated with a lower fungal burden and limited collagen increment in the pulmonary lesions. PTX treatment restored the levels of IFN-γ, MIP-1β, and IL-3 that had been down-regulated by Pb infection. Additionally, IL-12p70, IL-10, IL-13, and eotaxin were significantly increased, whereas Regulated upon Activation, Normal T cell Expressed and Secreted (RANTES) levels were decreased in the lungs of the Pb-infected-PTX-treated mice compared to the non-treated group.

Conclusions/significance

This study showed that PTX therapy administered at an “early” stage of granulomatous inflammation controlled the progress of the PCM by diminishing the pulmonary inflammation and the fungal burden and avoiding the appearance of collagen deposits in the pulmonary lesions.

Comparative clinical study between the effect of fenofibrate alone and its combination with pentoxifylline on biochemical parameters and liver stiffness in patients with non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease is a common health problem associated with increased liver and vascular specific complications.

AIM

The purpose of this study was to assess and compare the effect of fenofibrate alone or in combination with pentoxifylline on the measured biochemical parameters, inflammatory pathway and liver stiffness in patients with non-alcoholic fatty liver disease.

METHODS

The study design was randomized controlled trial. From July 2013 to June 2014, we recruited 90 non-alcoholic fatty liver patients from the Internal Medicine Department at Tanta University Hospital, Egypt. They were classified randomly into two groups to receive fenofibrate 300 mg daily or fenofibrate 300 mg daily plus pentoxifylline 1200 mg/day in three divided doses for 24 weeks. Fasting blood sample was obtained before and 24 weeks after treatment for biochemical analysis of liver and lipid panels, tumor necrosis factor-alpha, hyaluronic acid, transforming growth factor beta 1, fasting plasma insulin and fasting glucose. Liver stiffness measurement was carried out using fibro-scan. Data were statistically analyzed by paired and unpaired Student's t test.

RESULTS

The data obtained suggests that adding pentoxifylline to fenofibrate does not provide a beneficial effect on lipid panel, but has a beneficial effect on indirect biochemical markers of hepatic fibrosis, a direct marker linked to matrix deposition (hyaluronic acid), a cytokine/growth factor linked to liver fibrosis (transforming growth factor beta 1), the inflammatory pathway, insulin resistance and liver stiffness as compared to fenofibrate alone.

CONCLUSION

The combination pentoxifylline plus fenofibrate may represent a new therapeutic strategy for non-alcoholic fatty liver disease as it resulted in more beneficial effects on direct and indirect markers of liver fibrosis, liver stiffness, insulin resistance and inflammatory pathway implicated in NAFLD.

Nonalcoholic fatty liver disease: new treatments

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease is the most common cause of liver dysfunction in the western world because of its close association with obesity, insulin resistance and dyslipidaemia. Nonalcoholic steatohepatitis (NASH) is a particular health concern due to the increased morbidity and mortality associated with progressive disease. At present, without specific targeted pharmacological therapies, the mainstay of therapy remains weight loss through dietary modification and lifestyle change; thus, the purpose of this review is to summarize the recent evidence for current and emerging therapies in NASH.

RECENT FINDINGS

Some existing medications, including pioglitazones and angiotensin receptor antagonists, may be repurposed to help treat this condition. Vitamin E may improve histology in NASH, but safety issues limit its use. Recently, a number of novel agents specifically targeting nonalcoholic fatty liver disease pathogenesis have entered clinical trials, including the farnesoid X receptor agonist obeticholic acid, which has shown significant histological improvements in steatohepatitis and fibrosis.

SUMMARY

Diet/lifestyle modification remains the mainstay of treatment. For patients with NASH and advanced fibrosis, current liver-directed pharmacotherapy with vitamin E and pioglitazone offer some benefits; obeticholic acid appears promising and is currently being tested. Comorbidities must be diagnosed and treated; cardiovascular disease remains a primary cause of death in these patients.

4Ps medicine of the fatty liver: the research model of predictive, preventive, personalized and participatory medicine-recommendations for facing obesity, fatty liver and fibrosis epidemics

Relationship between adipose tissue and fatty liver, and its possible evolution in fibrosis, is supported by clinical and research experience. Given the multifactorial pathogenesis of non-alcoholic fatty liver disease (NAFLD), treatments for various contributory risk factors have been proposed; however, there is no single validated therapy or drug association recommended for all cases which can stand alone. Mechanisms, diagnostics, prevention and treatment of obesity, fatty liver and insulin resistance are displayed along with recommendations and position points. Evidences and practice can get sustainable and cost-benefit valuable outcomes by participatory interventions. These recommendations can be enhanced by comprehensive research projects, addressed to societal issues and innovation, market appeal and industry development, cultural acceptance and sustainability. The basis of participatory medicine is a greater widespread awareness of a condition which is both a disease and an easy documented and inclusive clue for associated diseases and unhealthy lifestyle. This model is suitable for addressing prevention and useful for monitoring improvement, worsening and adherence with non-invasive imaging tools which allow targeted approaches. The latter include health psychology and nutritional and physical exercise prescription expertise disseminated by continuous medical education but, more important, by concrete curricula for training undergraduate and postgraduate students. It is possible and recommended to do it by early formal teaching of ultrasound imaging procedures and of practical lifestyle intervention strategies, including approaches aimed to healthier fashion suggestions. Guidelines and requirements of research project funding calls should be addressed also to NAFLD and allied conditions and should encompass the goal of training by research and the inclusion of participatory medicine topics. A deeper awareness of ethics of competences in health professionals and the articulation of knowledge, expertise and skills of medical doctors, dieticians, health psychologists and sport and physical exercise graduates are the necessary strategy for detectin a suboptimal health status and achieving realistically beneficial lifestyle changes. “The devil has put a penalty on all things we enjoy in life. Either we suffer in health or we suffer in soul or we get fat” (Albert Einstein); the task of medical research and intervention is to make possible to enjoy life also without things that make sufferance in health and souls and which excessively increase body fat.

Treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is now the commonest cause of chronic liver disease in developed countries. Treatment depends on the stage of disease, and non-invasive methods for risk stratification are urgently needed. Lifestyle modification (aimed at weight loss and increasing physical activity) and management of the features of metabolic syndrome are vital for all patients with NAFLD. Metformin is the first-line therapy for diabetic patients with NAFLD and also reduces the risk of hepatocellular carcinoma. Clinicians should have a low threshold for introducing a statin for the management of dyslipidaemia. Antihypertensive agents that target the renin-angiotensin system should be first-line in NAFLD for the management of hypertension. For patients with progressive disease, liver-directed pharmacotherapy with vitamin E should be considered. Non-alcoholic steatohepatitis cirrhosis is an increasingly common indication for liver transplantation.

Pentoxifylline and propentofylline prevent proliferation and activation of the mammalian target of rapamycin and mitogen activated protein kinase in cultured spinal astrocytes

Astrocyte activation is an important feature in many disorders of the central nervous system, including chronic pain conditions. Activation of astrocytes is characterized by a change in morphology, including hypertrophy and increased size of processes, proliferation, and an increased production of proinflammatory mediators. The xanthine derivatives pentoxifylline and propentofylline are commonly used experimentally as glial inhibitors. These compounds are generally believed to attenuate glial activity by raising cyclic AMP (cAMP) levels and inhibiting glial tumor necrosis factor (TNF) production. In the present study, we show that these substances inhibit TNF and serum-induced astrocyte proliferation and signaling through the mammalian target of rapamycin (mTOR) pathway, demonstrated by decreased levels of phosphorylated S6 kinase (S6K), commonly used as a marker of mTOR complex (mTORC) activation. Furthermore, we show that pentoxifylline and propentofylline also inhibit JNK and p38, but not ERK, activation induced by TNF. In addition, the JNK antagonist SP600125, but not the p38 inhibitor SB203580, prevents TNF-induced activation of S6 kinase, suggesting that pentoxifylline and propentofylline may regulate mTORC activity in spinal astrocytes partially through inhibition of the JNK pathway. Our results suggest that pentoxifylline and propentofylline inhibit astrocyte activity in a broad fashion by attenuating flux through specific pathways.

Features, diagnosis, and treatment of nonalcoholic fatty liver disease

As the global incidence of obesity has increased, nonalcoholic fatty liver disease (NAFLD) has become a worldwide health concern. NAFLD occurs in children and adults of all ethnicities and includes isolated fatty liver and nonalcoholic steatohepatitis (NASH). Patients with NASH are at risk for developing cirrhosis, hepatic decompensation, and hepatocellular carcinoma and have increased all-cause mortality. NAFLD is associated with a variety of clinical conditions and is an independent risk factor for hepatocellular carcinoma. The pathogenesis of NAFLD and the specific steps that lead to NASH and advanced fibrosis are not fully understood, although researchers have found that a combination of environmental, genetic, and metabolic factors lead to advanced disease. There have been improvements in noninvasive radiographic methods to diagnose NAFLD, especially for advanced disease. However, liver biopsy is still the standard method of diagnosis for NASH. There are many challenges to treating patients with NASH, and no therapies have been approved by the U.S. Food and Drug Administration; multimodal approaches are being developed and becoming the standard of care. We review pathogenesis and treatment approaches for the West's largest liver-related public health concern.

Hydrolysable tannins of tropical almond show antifibrotic effects in TGF-β1-induced hepatic stellate cells

BACKGROUND

Persistent activation of hepatic stellate cells (HSC-T6) has been known to cause liver fibrosis. In this study, our objective was to investigate the effects of chebulagic acid and chebulinic acid, two hydrolysable tannins of tropical almond (Terminalia chebula) fruits, on collagen synthesis and signal transduction in transforming growth factor-β1-stimulated HSC-T6 cells. The expression of Smad2, Smad3, Smad4, collagen I(α1)/III, and plasminogen activator inhibitor 1 (PAI-1) mRNAs was determined by reverse-transcription polymerase chain reaction and their protein levels were assessed by western blotting.

RESULTS

Results showed that chebulagic acid and chebulinic acid at 20 µmol L(-1) exhibited cytotoxic and anti-proliferative effects on HSC-T6 cells. They also significantly decreased the expression of Smd2, Smad3 and Smad4, and the synthesis of collagen, procollagen I (α1) and III, as well as suppressing the activation of PAI-1; these events consequently facilitated the resolution of fibrosis.

CONCLUSION

These results indicate that both chebulagic acid and chebulinic acid possess antifibrotic activity, and their mechanism of action could be through the inhibition of the Smad pathway.

Pentoxifylline improves nonalcoholic steatohepatitis: a randomized placebo-controlled trial

The primary aim of this study was to compare the effects of pentoxifylline (PTX) versus placebo on the histological features of nonalcoholic steatohepatitis (NASH). In all, 55 adults with biopsy-confirmed NASH were randomized to receive PTX at a dose of 400 mg three times a day (n = 26) or placebo (n = 29) over 1 year. The primary efficacy endpoint was defined as improvement in histological features of NASH through reduction in steatosis, lobular inflammation, and/or hepatocellular ballooning as reflected by a decrease of ≥ 2 points in the nonalcoholic fatty liver disease (NAFLD) activity score (NAS). After 1 year, intention-to-treat analysis showed a decrease of ≥ 2 points in the NAS in 38.5% of patients on PTX versus 13.8% of those on placebo (P = 0.036). Per protocol analysis, a decrease of ≥ 2 points in the NAS from baseline was observed in 50% of the patients on PTX versus 15.4% of those on placebo (P = 0.01). The mean change in NAS score from baseline was -1.6 in the PTX group, versus -0.1 in the placebo group (P < 0.001). PTX significantly improved steatosis (mean change in score -0.9 versus -0.04 with placebo, P < 0.001) and lobular inflammation (median change -1 versus 0 with placebo, P = 0.02). No significant effects in hepatocellular ballooning were observed. PTX also improved liver fibrosis (mean change in fibrosis score was -0.2 among those on PTX versus +0.4 among those on placebo, P = 0.038). Although not statistically significant (P = 0.17), improvement in fibrosis was observed in a greater proportion (35%) of patients in the PTX group compared to placebo (15%). Adverse effects were similar in both groups.

CONCLUSION

PTX improved histological features of NASH compared to placebo. PTX was well tolerated in patients with NASH.

Alterations in fibrosis-related gene expression and proteomic expression profile in rat hepatic stellate cells exposed to the cocktail

AIM: To investigate changes in the expression of fibrosis-related genes and proteomic expression profile in rat hepatic stellate cells (HSCs) exposed to the cocktail to explore potential anti-hepatic fibrosis mechanisms of the cocktail therapy.

METHODS: After HSCs were cultured in vitro and exposed to the cocktail for 24 h, the expression of TGF-β1, MMP-2 and TIMP-2 mRNAs and proteomic expression profile were measured by RT-PCR and SELDI-TOF-MS, respectively.

RESULTS: Compared to control cells, the expression level of MMP-2 mRNA significantly increased (0.094 ± 0.051 vs 0.023 ± 0.056, P < 0.05), and those of TGF-β1 and TIMP-2 mRNAs significantly decreased (0.301 ± 0.025 vs 0.503 ± 0.042; 0.719 ± 0.03 vs 1.204 ± 0.418, both P < 0.05) in HSCs exposed to the cocktail. A total of 176 differential proteins were identified between control cells and treated cells, of which 32 were up-regulated and 3 down-regulated.

CONCLUSION: The cocktail therapy exerts anti-hepatic fibrosis activity possibly by regulating the expression of related genes and proteins.

The effect of pentoxifylline and its metabolite-1 on inflammation and fibrosis in the TNBS model of colitis

TNBS-induced colitis has characteristics resembling human Crohn's disease including transmural inflammation, ulceration, and fibrosis. Current treatments target acute symptoms but do not necessarily prevent fibrotic complications of the disease. The aim of this study was to determine the effect of pentoxifylline and its primary metabolite (M-1) on fibrosis in the TNBS-induced colitis model. Myeloperoxidase activity and interleukin-18 are indicators of inflammation and were elevated in the TNBS model. The morphology damage score assesses colon damage and was also elevated in the TNBS model. Collagen as the indicator of fibrosis was quantified and visualized by the Sirius Red/Fast Green staining technique and collagen type I was assessed by Western analysis. Collagen was elevated in the TNBS-induced model. Pentoxifylline and M-1 treatment significantly attenuated colon damage and inflammation in TNBS-colitis (P<0.05). M-1 treatment significantly reduced the TNBS-induced increase in colon weight, colon thickness and total collagen content (P<0.05). Results suggest that pentoxifylline and M-1 inhibit intestinal fibrosis in this experimental model and may prove beneficial in the treatment of intestinal fibrosis associated with human Crohn's disease with the added benefit of inhibiting inflammation and ulceration. This is the first study to examine the effects of racemic M-1 in vivo and one of the few studies to examine the effect of drugs on both inflammation and fibrosis in an experimental model of colitis.

Attenuation of N-nitrosodiethylamine-induced liver fibrosis by high-molecular-weight fucoidan derived from Cladosiphon okamuranus

BACKGROUND AND AIM

Liver fibrosis is closely associated with the progression of various chronic liver diseases. Fucoidan exhibits different biological properties such as anti-inflammatory, anti-oxidant and anti-fibrotic activities. The aim of this study was to determine whether oral fucoidan administration inhibits N-nitrosodiethylamine (DEN)-induced liver fibrosis.

METHODS

Liver fibrosis was induced in rats by injecting DEN (50 mg/kg). Rats were given 2% of crude fucoidan solution or 2% of high-molecular-weight (HMW) fucoidan solution. They were divided into a crude fucoidan group, an HMW fucoidan group, a DEN alone group, a DEN + crude fucoidan group, a DEN + HMW fucoidan group and a control group.

RESULTS

Liver fibrosis and hepatic hydroxyproline levels were significantly more decreased in the DEN + HMW fucoidan group than in the DEN-alone group. Anti-fibrogenesis was unremarkable in the DEN + crude fucoidan group. Hepatic messenger RNA levels and immunohistochemistry of transforming growth factor beta 1 were markedly increased by DEN. This increase was attenuated by HMW fucoidan. Hepatic chemokine ligand 12 expression was increased by DEN. This increase was suppressed by HMW fucoidan. HMW fucoidan significantly decreased the DEN-induced malondialdehyde levels. Also, fucoidan markedly increased metallothionein expression in the liver. Fucoidan was clearly observed in the liver by immunohistochemical staining in HMW fucoidan-treated rats, while it was faintly stained in the livers of crude fucoidan-treated rats.

CONCLUSION

These findings suggest that the HMW fucoidan treatment causes anti-fibrogenesis in DEN-induced liver cirrhosis through the downregulation of transforming growth factor beta 1 and chemokine ligand 12 expressions, and that scavenging lipid peroxidation is well-incorporated in the liver.

Effects of the administration of pentoxifylline and prednisolone on the evolution of portal fibrogenesis secondary to biliary obstruction-an experimental study in growing animals

BACKGROUND

Many chronic liver diseases lead to progressive hepatic fibrosis, a condition that can ultimately result in loss of organ function and severe portal hypertension necessitating hepatic transplantation. Within the last few decades, studies have been conducted to demonstrate the possibility of drug modulation of hepatic fibrogenesis. Regarding biliary obstruction, it has been suggested that administration of corticosteroids could promote better late outcomes for children with biliary atresia submitted to Kasai's portoenterostomy. Models used to test potential antifibrogenic drugs such as pentoxifylline (PTX) have not included growing animals.

METHODS

In this experimental study, 119 young rats (21st or 22nd days) were submitted to laparotomy and common bile duct ligation (CBDL) or to sham surgery (SHAM). Animals were allocated into 5 groups, according to surgical procedure, and administered the following solutions: (1) CBDL + distilled water, (2) SHAM + distilled water, (3) CBDL + PTX, (4) CBDL + prednisolone (PRED), and (5) CBDL + PTX + PRED (PTX + PRED). Each group was further divided into 2 subgroups according to the length of the experiment (15 or 30 days). At the end of the defined period, animals were weighed, and a hepatic fragment was collected from each one for analyses.

RESULTS

The PTX animals exhibited increased weight gain compared to animals in the PRED or PTX + PRED groups. Animals from the 3 therapeutic groups (PTX, PRED, and PTX + PRED) showed diminished collagen-filled area in portal spaces. Total portal space area was increased in the PTX group.

CONCLUSIONS

Hepatic fibrosis induced by bile duct ligation in young rats could be modulated by pharmacologic interventions. Administration of PTX or PRED, or the combination of both, resulted in diminished collagen-filled areas in portal spaces.

Pentoxifylline prevents pig serum-induced rat liver fibrosis by inhibiting interleukin-6 production

BACKGROUND/AIM

Pig serum-induced rat liver fibrosis is a model of liver fibrosis in the absence of obvious hepatocyte injury. Penoxifylline (PTX), a xanthine derivative, which is a well-known suppressor of tumor necrosis factor-alpha (TNF-alpha) production from inflammatory cells, has also been shown to inhibit the growth of hepatic stellate cells and to inhibit collagen synthesis in these cells in vitro. We investigated the effect of PTX on pig serum-induced liver fibrosis in vivo, and assessed the mechanisms of prevention of fibrogenesis by this drug.

METHODS

Male Wistar rats were given intraperitoneal injections of 0.5 ml normal pig serum twice a week for 10 weeks with or without concomitant oral administration of PTX (20 mg/kg).

RESULTS

Rats that received pig serum showed significant liver fibrosis, and their serum interleukin-6 (IL-6) and hyaluronic acid levels were significantly increased. The serum levels of IL-6 were well correlated with the serum levels of hyaluronic acid, and increased as the liver fibrosis progressed. Penoxifylline prevented the development of fibrosis in this animal model and reduced the serum levels of IL-6 in a dose-dependent manner. In vitro, by the addition of PTX to the culture medium of the rat hepatic stellate cells (HSCs), the proliferation of the HSCs was significantly inhibited and IL-6 in the culture supernatant was also reduced significantly. Exogenous addition of IL-6 partially restored the proliferation.

CONCLUSION

Penoxifylline prevents pig serum-induced rat liver fibrosis by inhibiting the proliferation of HSCs and by inhibiting the production of IL-6 from HSCs.

Hepatic fibrosis -- overview

The study of hepatic fibrosis, or scarring in response to chronic liver injury, has witnessed tremendous progress in the past two decades. Clarification of the cellular sources of scar, and emergence of hepatic stellate cells not only as a fibrogenic cell type, but also as a critical immunomodulatory and homeostatic regulator are among the most salient advances. Activation of hepatic stellate cells remains a central event in fibrosis, complemented by evidence of additional sources of matrix-producing cells including bone marrow, portal fibroblasts, and epithelial-mesenchymal transition from both hepatocytes and cholangiocytes. A growing range of cytokines and their receptors and inflammatory cell subsets have further expanded our knowledge about this dynamic process. Collectively, these findings have laid the foundation for continued elucidation of underlying mechanisms, and more importantly for the implementation of rationally based approaches to limit fibrosis, accelerate repair and enhance liver regeneration in patients with chronic liver disease.

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.

Pentoxifylline downregulates alpha (I) collagen expression by the inhibition of Ikappabalpha degradation in liver stellate cells

Overproduction of collagen (I) by activated hepatic stellate cells is a critical step in the development of liver fibrosis. It has been established that these cells express interleukin (IL)-6 and respond to this cytokine with an increase in alpha(I) collagen. Pentoxifylline, a methylxanthine derivate, has been reported to have antifibrotic properties, but the mechanism responsible for this effect is unknown. The aim of this study was to determine the effect of pentoxifylline on acetaldehyde-induced collagen production in a rat hepatic stellate cell line (CFSC-2G cells). Cells were treated with 100 microM acetaldehyde and 200 microM pentoxifyline for 3 h. IL-6 and alpha(I) collagen messenger RNA (mRNA) were determined by reverse transcriptase polymerase chain reaction (RT-PCR) assay. NFkappaB activation was determined by electrophoretic mobility shift assay. To corroborate NFkappaB participation in pentoxifylline effect, cells were pretreated with 10 microM TPCK, a NFkappaB inhibitor. IkappaBalpha was determined by Western blot. IL-6 expression decreased significantly in acetaldehyde-pentoxifylline-treated cells. Acetaldehyde-treated cells pretreated with an anti-IL-6 monoclonal antibody did not show any increase in alpha (I) collagen expression. Acetaldehyde-treated cells increased 1.48 times NFkappaB activation, whereas acetaldehyde-pentoxifylline-treated cells decreased NFkappaB activation to control values. TPCK pretreated acetaldehyde cells did not present NFkappaB activation. To corroborate NFkappaB participation in pentoxifylline effect, IkappaBalpha was determined. IkappaBalpha protein level decreased 50% in acetaldehyde-treated cells, while acetaldehyde-pentoxifylline-treated cells showed IkappaBalpha control cells value. The data suggest that acetaldehyde induced alpha(I) collagen and IL-6 expression via NFkappaB activation. Pentoxifylline prevents acetaldehyde-induced alpha(I) collagen and IL-6 expression by a mechanism dependent on IkappaBalpha degradation, which in turn blocks NFkappaB activation.

A novel drug interaction between the quinolone antibiotic ciprofloxacin and a chiral metabolite of pentoxifylline

Pentoxifylline (PTX), a methylxanthine derivative, is metabolized to seven compounds in vivo, with metabolites 1 and 5 possessing biologic activity. Metabolite-1 is a chiral molecule and its S-enantiomer is selectively formed during PTX metabolism in vivo. We have developed a reproducible method of synthesizing a racemic mixture of the chiral metabolite-1 (M-1) of PTX. In this study, we examined the kinetics of racemic M-1 in mice compared to PTX. An interaction between PTX and the quinolone antibiotic ciprofloxacin has been demonstrated. A goal of this study was to determine if a similar interaction occurs between ciprofloxacin and M-1 in vivo. M-1 and PTX had similar absorption and elimination rates. M-1 was rapidly converted to PTX, while very little PTX was converted to M-1 in vivo. The peak concentration of biologically active drug (PTX+M-1) was 36% higher when M-1 was administered compared to PTX. Combination of ciprofloxacin and PTX significantly increased serum concentrations of both PTX and M-1 (2-fold) compared to controls. The combination of M-1 and ciprofloxacin significantly increased serum concentration of M-1 (3-fold) and PTX (2-fold). The ciprofloxacin/M-1 combination produced a significantly higher sera concentration of bioactive drug compared to all other groups suggesting that this combination may enhance the anti-fibrogenic effect.

Pharmacodynamics of pentoxifylline and/or praziquantel in murine schistosomiasis mansoni

Pentoxifylline (PTX) was proved to exert both anti-inflammatory and anti-fibrotic effects, and was used therapeutically in this experimental model to investigate its role alone or with praziquantel (PZQ) in Schistosoma mansoni-infected mice, and to explore its impact on the tissue expression of transforming growth factor-beta1 (TGF-beta1). S. mansoni-infected mice were divided into seven groups: Control untreated (I), treated with curative dose of PZQ, 500 mg/kg/day for 2 consecutive days (II), or subcurative dose, 100 mg/kg/day for 2 consecutive days (III), treated with PTX (10 mg/kg/day for 5 days/wk) alone for 4 weeks (IV) or in addition to subcurative dose of PZQ (V), and treated with PTX alone for 8 weeks (VI) or in addition to subcurative dose of PZQ (VII). All animals were killed 10 weeks post infection. Parasitological assessment of worm burden, tissue egg load and oogram pattern was carried out. The degree of granulomatous fibrosis and eosinophilic cell population was quantified in Sirius-red-stained sections and tissue transforming growth factor beta-1 expression was estimated immunohistochemically. Serum ALAT and GGT, as well as hepatic content of reduced GSH, were measured. The results revealed the highest percent of worm reduction and dead ova in groups (II) and (VII) accompanied by significant diminution in granulomatous parameters, collagen content and TGF-beta1 tissue expression. Moreover, treatments with PTX and/or PZQ ameliorated the liver functions. In conclusion, prolonged treatment with PTX has a potent anti-fibrogenic role especially when used in the early stages of infection, with limited toxic effects on schistosome worms and eggs. Thus, PTX can be used as an adjuvant therapeutic tool with anti-helminthic drugs in the treatment of human schistosomiasis.

Fibroblast differentiation in wound healing and fibrosis

The contraction of granulation tissue from skin wounds was first described in the 1960s. Later it was discovered that during tissue repair, fibroblasts undergo a change in phenotype from their normal relatively quiescent state in which they are involved in slow turnover of the extracellular matrix, to a proliferative and contractile phenotype termed myofibroblasts. These cells show some of the phenotypic characteristics of smooth muscle cells and have been shown to contract in vitro. In the 1990s, a number of researchers in different fields showed that myofibroblasts are present during tissue repair or response to injury in a variety of other tissues, including the liver, kidney, and lung. During normal repair processes, the myofibroblastic cells are lost as repair resolves to form a scar. This cell loss is via apoptosis. In pathological fibroses, myofibroblasts persist in the tissue and are responsible for fibrosis via increased matrix synthesis and for contraction of the tissue. In many cases this expansion of the extracellular matrix impedes normal function of the organ. For this reason much interest has centered on the derivation of myofibroblasts and the factors that influence their differentiation, proliferation, extracellular matrix synthesis, and survival. Further understanding of how fibroblast differentiation and myofibroblast phenotype is controlled may provide valuable insights into future therapies that can control fibrosis and scarring.

Precision-cut fibrotic rat liver slices as a new model to test the effects of anti-fibrotic drugs in vitro

BACKGROUND/AIMS

Current cell culture models contributed significantly to the study of liver fibrosis and the testing of anti-fibrotic drugs but mimic the complex in vivo milieu poorly. Therefore, we evaluated fibrotic rat liver slices as a new, more physiologic in vitro model to test anti-fibrotic compounds.

METHODS

Precision-cut slices (8 mm diameter, 250 microm thickness) were prepared from fibrotic rat livers three weeks after bile-duct ligation and incubated for 0-48 h, during which viability and progression of the fibrotic process was evaluated. In addition, the effects of pentoxifylline, gleevec, and dexamethasone on mRNA expression of markers for fibrosis were determined.

RESULTS

Fibrotic liver slices remained viable during 48 h of incubation, with increasing alphaSMA and pro-collagen 1a1 mRNA expression, and alphaSMA and collagen protein content after prolonged incubation. Addition of pentoxifylline, gleevec, or dexamethasone during incubation dose-dependently inhibited pro-collagen-1a1 and alphaSMA mRNA expression after 24h of incubation without influencing slice viability.

CONCLUSIONS

Fibrotic liver slices are a promising tool to test anti-fibrotic drugs in vitro in a multicellular, fibrotic milieu, which cannot be achieved in vitro using other models. Importantly, this method may provide the opportunity to study anti-fibrotic compounds not only in animal but also in fibrotic human liver tissue.

Direct and indirect evidence for the reversibility of cirrhosis

The aim of this study was to assess the reversibility of cirrhosis after therapy in a large series of patients with cirrhosis from various etiologies. We performed a retrospective study of 113 patients with biopsy-proven cirrhosis who underwent specific therapy and follow-up biopsies. Two pathologists performed blinded analyses of indirect biochemical and morphological signs of cirrhosis. Fourteen (12.4%) of the 113 cirrhotic patients had biopsy-proven disappearance of cirrhosis, defined as a decrease of 2 or greater in their METAVIR fibrosis score: 8 were related to hepatitis C virus, 3 to hepatitis B virus, and 3 to autoimmune cirrhosis. Necro-inflammatory activity decreased from 2.4 +/- 0.65 to 0.85 +/- 0.9 (P = .004), and fibrosis from 4 to 1.7 +/- 0.61 (P = .001). Prothrombin time (n = 1), platelet count (n = 2), serum albumin level (n = 2), and ultrasound abnormalities (n = 6) normalized in patients who had initial abnormalities. Hyaluronic acid and procollagen type III serum level decreased in all. In the 11 patients with regression of viral cirrhosis, 2 were nonresponders and 9 were responders, including 2 relapsers. The 3 patients with regressive autoimmune cirrhosis were complete responders to immunosupressive therapy. Using repeated liver biopsies, clinicobiochemical, radiologic, and endoscopic tests, we provide evidence for potential reversibility of cirrhosis after long-lasting suppression of the necro-inflammatory activity of liver disease.

Pentoxifylline fails to attenuate fibrosis in dystrophic (mdx) diaphragm muscle

Fibrosis is a common pathological feature observed in muscle from patients with Duchenne muscular dystrophy and in mdx diaphragm. The purpose of this study was to determine whether pentoxifylline (PTX) treatment for 4 weeks (16 mg/kg/day) could significantly attenuate the process of fibrosis in diaphragm muscle from mdx mice. PTX treatment had no impact on in vitro diaphragm muscle contractile function. In addition, diaphragm muscle hydroxyproline concentration and the level of type I and III collagen and TGF-beta1 mRNA were unaffected by PTX treatment. These findings do not support the use of PTX as an antifibrotic drug for the treatment of muscular dystrophy.

Hepatic fibrosis: molecular mechanisms and drug targets

Liver fibrosis is the common response to chronic liver injury, ultimately leading to cirrhosis and its complications, portal hypertension, liver failure, and hepatocellular carcinoma. Efficient and well-tolerated antifibrotic drugs are currently lacking, and current treatment of hepatic fibrosis is limited to withdrawal of the noxious agent. Efforts over the past decade have mainly focused on fibrogenic cells generating the scarring response, although promising data on inhibition of parenchymal injury and/or reduction of liver inflammation have also been obtained. A large number of approaches have been validated in culture studies and in animal models, and several clinical trials are underway or anticipated for a growing number of molecules. This review highlights recent advances in the molecular mechanisms of liver fibrosis and discusses mechanistically based strategies that have recently emerged.

The inhibitory effect of a Korean herbal medicine, Zedoariae rhizoma, on growth of cultured human hepatic myofibroblast cells

The aim of this study was to assess the effect of ZR on the growth of cultured human hepatic myofibroblast cells (hMF). The zedoary (Zedoariae Rhizoma) made from the dried rhizome of Curcuma zedoaria Roscoe is an herbal drug used as an aromatic stomachic. The plant is a perennial herb which is natively distributed throughout Korea and is a traditional Korean herbal medicine. Zedoariae rhizoma is a bioactive traditional medicine with anti-tumor, anti-atherosclerosis, anti-inflammation, and growth-regulating properties. During the course of liver fibrogenesis, hMF, mostly derived from hepatic stellate cells, proliferate and synthesize excessive amounts of extracellular matrix components. To evaluate the antiproliferative effect of a traditional herbal medicine, Zedoariae rhizoma water extracts (ZR) was examined on the growth inhibition of hMF since proliferation of hMF is known to be central for the development of fibrosis during liver injury, and factors that may limit their growth are potential antifibrotic agents. The aim of this study was to test the effects of ZR on the proliferation in cultured hMF. hMF were obtained by outgrowth from human liver explants. ZR markedly reduced serum driven cell proliferation, as assessed by nuclear autoradiography experiments and measurement of actual cell growth. Growth inhibition was totally reversed after removal of the ZR. ZR potently inhibited hMF growth (IC50 = 8.5 microg/ml), in a pertussis toxin-insensitive manner. Analysis of the mechanisms involved in growth inhibition revealed that ZR rapidly increased prostaglandin E2 production and in turn cAMP, which inhibited hMF proliferation, did not affect cAMP levels. Production of cAMP by ZR was abolished by NS-398, a selective inhibitor of cycloxygenase (COX)-2. Also, ZR potently induced COX-2 protein expression. Blocking COX-2 by NS-398 blunted the antiproliferative effect of ZR. We conclude that ZR inhibits proliferation of hMF, probably via an intracellular mechanism, through early COX-2-dependent release of prostaglandin E2 and cAMP, and delayed COX-2 induction. Our results indicated a novel role for ZR as a growth inhibitory mediator and pointed out its potential involvement in the negative regulation of liver fibrogenesis. The results that ZR exhibits potent antiproliferative and antifibrogenic effects toward hMF, indicated that ZR might have therapeutic implications in chronic liver disease.

Zedoariae rhizoma and curcumin inhibits platelet-derived growth factor-induced proliferation of human hepatic myofibroblasts

During the course of liver fibrogenesis, hepatic myofibroblast cells (hMF), mostly derived from hepatic stellate cells (HSC), proliferate and synthesize excessive amounts of extracellular matrix (ECM) components. To evaluate the antiproliferative effect of a traditional herbal medicine, Zedoariae rhizoma water extracts (ZR) was examined on the growth inhibition of human hMF since proliferation of hMF is known to be central for the development of fibrosis during liver injury, and factors that may limit their growth are potential antifibrotic agents. The aim of this study was to test the effects of ZR on the proliferation and to clarify the molecular mechanisms of ZR inhibition of HSC proliferation in cultured human hMF. The cells were stimulated by platelet-derived growth factor (PDGF)-BB in the presence or absence of ZR. Proliferation was determined by bromodeoxy-uridine (BrdU) incorporation. The mRNA expressions of collagen alpha1(I) and (IV) were evaluated by a quantitative reverse transcription-polymerase chain reaction (RT-PCR). PDGF-receptor tyrosine phosphorylation was detected using anti-phosphotyrosine antibody. PDGF-receptor radioligand binding assay was performed by [125I]PDGF-BB. ZR inhibited the PDGF-BB-induced cell-proliferation and collagen alpha1(I) and (IV) mRNA expressions. ZR reduced the autophosphorylation of the PDGF-receptor. ZR blocked PDGF-BB binding to its receptor in a non-competitive manner. Furthermore, the 80% aqueous acetone extract of ZR was also found to show a decreasing effect against the proportion of S phase cells after PDGF stimulation. To clarify the active compounds, the principal constituents of seven sesquiterpenes (curdione, dehydrocurdione, germacrone, curcumenol, isocurcumenol, zedoarondiol and curcumenone) and a diarylheptanoid (curcumin) were examined. Among them, curcumin was found to decrease the proportion of S phase cells after PDGF stimulation at a dose of 30-50 microM. Potent antiproliferative and antifibrogenic effects of ZR toward hMF indicated that ZR might have therapeutic implications in chronic liver disease, indicating a novel role for ZR as a growth inhibitory mediator and pointing out its potential involvement in the negative regulation of liver fibrogenesis. In conclusion, ZR has an inhibitory effect on PDGF-induced proliferation of hMF and the blocking of PDGF-BB binding to its receptor may be the mechanism behind this effect.

Pentoxifylline attenuates steatohepatitis induced by the methionine choline deficient diet

BACKGROUND/AIMS

Feeding mice a methionine choline deficient (MCD) diet serves as a nutritional model of non-alcoholic steatohepatitis (NASH). NASH and alcohol-induced steatohepatitis are histologically similar, suggesting a similar pathogenesis. Pentoxifylline (PTX) attenuates TNF-alpha production, acts as an antioxidant and decreases mortality in alcoholic steatohepatitis. The aim of our study is to determine if PTX attenuates MCD diet induced steatohepatitis and determine the mechanism of this effect.

METHODS

Mice were placed on an MCD or control diet for 2 weeks and were treated with or without PTX. Serum ALT, liver histology, and inflammatory mechanisms were evaluated.

RESULTS

PTX attenuates MCD diet induced steatohepatitis, decreasing both serum ALT levels and hepatic inflammation. Serum ALT levels were reduced approximately 50% in the MCD+PTX group compared to the MCD group. Hepatic glutathione levels were significantly higher in the MCD+PTX group compared to the MCD group. There was also a reduction in TNF-alpha mRNA in female mice treated with PTX. MCD+PTX mice had increased hepatic triglyceride content compared to the MCD mice, but less histologic evidence of inflammation despite the increased steatosis. Serum lipid and bile salt levels also were similar in PTX and vehicle control treated mice.

CONCLUSIONS

PTX decreases serum ALT levels and hepatic inflammation in the MCD model of steatohepatitis, likely via increasing glutathione levels or reducing TNF-alpha expression.

Treatment of thioacetamide-induced liver cirrhosis by the Ras antagonist, farnesylthiosalicylic acid

BACKGROUND/AIMS

Several studies have indicated increased expression of the Ras protooncogenes in liver cirrhosis. In a previous study in rats, we have shown that a synthetic Ras antagonist, S-farnesylthiosalicylic acid (FTS), could inhibit the development of liver cirrhosis. The aim of the current study was to examine whether FTS will accelerate the resolution of liver cirrhosis induced in rats by thioacetamide.

METHODS

Cirrhosis was induced in male Wistar rats by intraperitoneal (i.p.) administration of thioacetamide (200 mg/kg twice weekly for 12 weeks). In the treated group, the Ras antagonist FTS (5 mg/kg, i.p./3 times/week) was administered for 8 weeks after liver cirrhosis has already been established. Control cirrhotic rats received PBS injections for 8 weeks.

RESULTS

Rats treated with FTS for 8 weeks had lower histopathologic score of fibrosis (P = 0.01), lower hepatic hydroxyproline levels (P = 0.0002) and lower spleen weight (P = 0.02) than the cirrhotic rats treated with PBS. Following FTS treatment, the MMP-2 and MMP-9-induced collagenolytic activity and TIMP-2 expression, were increased in FTS-compared to PBS-treated rats. TUNEL assay of liver sections performed 8 weeks after thioacetamide withdrawal showed increased apoptotic figures in both groups (P = NS).

CONCLUSIONS

These results indicate that the Ras antagonist FTS accelerates the regression of experimentally-induced hepatic cirrhosis. The mechanism may involve increased collagenolytic activity.

In vivo inefficiency of pentoxifylline and interferon-alpha on hepatic fibrosis in biliary-obstructed rats: assessment by tissue collagen content and prolidase activity

BACKGROUND AND AIM

To evaluate the possible antifibrotic effects of two drugs, pentoxifylline (PTX) and interferon (IFN)-alpha as well as their combination, on a bile-duct-ligated rat hepatic fibrosis model.

METHODS

Bile ducts of 34 female Wistar rats were ligated, and 24 bile ducts were sham operated. Bile-duct-ligated rats were divided into four groups, in which either sterile saline, IFN-alpha (100 000 IU/3 days a week), PTX (50 mg/kg/day) or IFN-alpha + PTX were administered. Sham-operated rats were treated at the same doses. On the 28th day, rats were decapitated to obtain blood for the measurements of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT) and bilirubins. Serum prolidase was assayed at the beginning and at the end of the study by the modified Chinard's colorimetric method. Liver prolidase was assayed after tissue homogenization. Liver collagen content was determined by the dye elution method described by Lopez de Leon. Morphometric-densitometric measurements of hepatic fibrosis were quantified by computerized image analysis.

RESULTS

The AST, ALT, ALP, GGT and bilirubins, liver prolidase enzyme activity, collagen content and hepatic collagen surface density were found to be increased in bile-duct-ligated rats on day 28. There was no statistically significant recovery or even a change in collagen turnover rate in rats treated with alternate regimens applied in the study (P > 0.05).

CONCLUSION

Pentoxifylline, IFN-alpha and their combination have no beneficial effect on experimental fibrosis induced by biliary obstruction.

Effects of pentoxifylline on the hepatic content of TGF-β1 and collagen in Schistosomiasis japonica mice with liver fibrosis

AIM: To study the effects of pentoxifylline (PTX) on the content of hepatic TGF-β1, type I and type III collagen in schistosomiasis japonica mice with liver fibrosis and its mechanism of anti-fibrosis.

METHODS: Forty mice with schistosomiasis were divided into four groups: one group as control without any treatment, other three were treated with Praziquantel 500 mg/(kg·d)for 2 d, high dose PTX 360 mg/(kg·d) for 8 wk, and low dose PTX 180 mg/(kg·d) for 8 wk respectively. Immunohistochemical technique and multimedia color pathographic analysis system were applied to observe the content change of hepatic TGF-β1, type I and type III collagen in schistosomiasis japonica mice with liver fibrosis before and after PTX treatment.

RESULTS: Effects of PTX on the content change of hepatic TGF-β1, type I and type III collagen in schistosomiasis japonica mice with liver fibrosis were related to the dosage of PTX, high dose PTX treated group could significantly reduce the content of TGF-β1 (0.709 ± 0.111), type I (0.644 ± 0.108) and type III (0.654 ± 0.152) collagen compared with those of control group (0.883 ± 0.140, 0.771 ± 0.156, 0.822 ± 0.129) with statistical significance (P < 0.05). Low dose PTX could also reduce the hepatic content of TGF-β1 (0.752 ± 0.152), type I (0.733 ± 0.117) and type III (0.788 ± 0.147) collagen, but without statistical significance (P > 0.05). Both high dose and low dose PTX groups have significant differences on the content of TGF-β1, type I and type III collagen (P < 0.05, P < 0.05, P < 0.01, respectively).

CONCLUSION: High dose of PTX treatment could reduce the content of hepatic TGF-β1, type I and type III collagen significantly in schistosomiasis japonica mice with liver fibrosis, and thus plays its role of antifibrosis.

Quantitative and qualitative interferences of pentoxifillyne on hepatic Schistosoma mansoni granulomas: effects on extracellular matrix and eosinophil population

Mast cells and eosinophils actively participate in tissue repair and are prominent components of Schistosoma mansoni granulomas. Since pentoxifillyne (PTX) is an immunomodulatory and antifibrotic substance, we aimed to characterize, by morphological techniques, the effect of this drug on fibrosis developed inside murine hepatic schistosomal granulomatous reaction, beyond the quantification of eosinophil and mast cell populations. The drug (1 mg/100 g animal weight) was administrated from 35 to 90 days post-infection, when the animals were killed. The intragranulomatous interstitial collagen network was analyzed by confocal laser scanning microscopy, the number of eosinophils and mast cells was quantified and the results were validated by t-student test. Treatment did not interfere on the granuloma evolution but caused a significant decrease in the total and involutive number of hepatic granulomas (p = 0.01 and 0.001, respectively), and in the intragranulomatous accumulation of eosinophils (p = 0.0001). Otherwise, the number of mast cells was not significantly altered (p = 0.9); however, it was positively correlated with the number of granulomatous structures (r = 0.955). In conclusion, PTX does not affect development and collagen deposition in S. mansoni murine granuloma, but decreases the intragranulomatous eosinophil accumulation possibly due to its immunomodulatory capability, interfering in cellular recruitment and/or differentiation.

A pilot study of pentoxifylline for the treatment of primary sclerosing cholangitis

OBJECTIVE

There is no effective therapy for patients with primary sclerosing cholangitis (PSC). Rats with experimental small bowel bacterial overgrowth develop hepatobiliary injury similar to PSC. The hepatobiliary injury results from peptidoglycan-polysaccharide-mediated activation of Kupffer cells, release of cytokines such as tumor necrosis factor (TNF-alpha), and is prevented by pentoxifylline. Our aims were to assess the safety and effects of pentoxifylline on symptoms and biochemical liver tests in patients with PSC.

METHODS

A total of 20 patients with clinical, cholangiographic, and histological features of PSC of varying severity were treated with pentoxifylline sustained release (SR) tablets (400 mg q.i.d.) for < or = 1 yr. Serum alkaline phosphatase, aspartate aminotransferase, and bilirubin were monitored every 3 months for 1 year; serum TNF-alpha and TNF receptor subtypes I and II were assessed at baseline and 1 year.

RESULTS

Of 20 patients, 16 tolerated pentoxifylline and completed the study. Two patients were withdrawn because of severe nausea, and two patients were noncompliant with medication and withdrew. Pentoxifylline did not significantly alter symptoms of fatigue or pruritus, serum liver tests, serum TNF-alpha or TNF receptor levels.

CONCLUSIONS

In the current regimen, pentoxifylline alone does not significantly improve symptoms or liver tests in patients with PSC.

Deactivation of cultured human liver myofibroblasts by trans-resveratrol, a grapevine-derived polyphenol

Liver myofibroblasts are major actors in the development of liver fibrosis and cancer progression. There is a large interest in drugs that might deactivate these cells. Many studies have shown that the grapevine-derived polyphenol, trans-resveratrol, and other stilbenes have therapeutic potential in some diseases. In this work, we have studied the effect of grapevine polyphenols on cultured human liver myofibroblasts. We have shown that trans-resveratrol profoundly affects myofibroblast phenotype. Trans-resveratrol induced morphological modifications. It markedly reduced proliferation of myofibroblasts in a dose-dependent manner. Trans-resveratrol also decreased the expression of alpha smooth muscle actin (alpha-SMA) without affecting vimentin or beta-cytoplasmic actin expression. It decreased myofibroblast migration in a monolayer wounding assay. We also showed that trans-resveratrol inhibited the messenger RNA (mRNA) expression of type I collagen. Finally, it decreased the secretion of matrix metalloproteinase 2 (MMP-2). We conclude that trans-resveratrol can deactivate human liver myofibroblasts. In the second part of this study, we have shown that neither trans-piceid (a glycosylated analog) nor trans-piceatannol (a hydroxylated analog) reproduces trans-resveratrol effects on liver myofibroblasts. We finally show that, although trans-resveratrol decreases the proliferation of skin fibroblast and vascular smooth muscle cells, it does not affect their expression of alpha-SMA, which indicates some cell specificity.

Matrix metalloproteinase-2 activation in human hepatic fibrosis regulation by cell-matrix interactions

Matrix metalloproteinase-2 (MMP-2) is involved in extracellular matrix remodeling. It is secreted as a proenzyme and activated by membrane type-MMPs (MT-MMP), such as MT1-MMP. In liver fibrosis, MMP-2 is highly expressed in myofibroblasts and may have a profibrogenic role. The mechanisms of its activation in the liver are still unclear. The aim of this work was to show that pro-MMP-2 is efficiently activated in human fibrotic liver and to investigate the role of cell-matrix interactions in this process. Liver specimens obtained from patients with active cirrhosis were compared to normal liver specimens. Human hepatic myofibroblasts were cultured either on plastic, fibronectin, laminin, or on collagen I gels. MMP-2 activity was visualized by gelatin zymography. MMP-2 active form (59 kd) was detected in active cirrhosis but not in normal liver. Myofibroblasts cultured on plastic, fibronectin, or laminin predominantly expressed inactive pro-MMP-2 (66 kd). In contrast, myofibroblasts cultured on collagen I markedly activated the enzyme. Similar results were obtained using membrane fractions from cells previously cultured on collagen or plastic. Activation was inhibited by the tissue inhibitor of metalloproteinases-2 but not by tissue inhibitor of metalloproteinases-1, implicating a MT-MMP-mediated process. Culture on collagen I up-regulated MT1-MMP protein detected by Western blotting, but decreased MT1-MMP mRNA. This study shows that MMP-2 is activated in fibrotic liver. It suggests that interactions between collagen I and myofibroblasts promote this process through a post-translational increase of MT1-MMP expression in these cells.

Liver fibrogenesis and the role of hepatic stellate cells: new insights and prospects for therapy

Hepatic fibrosis is a wound-healing response to chronic liver injury, which if persistent leads to cirrhosis and liver failure. Exciting progress has been made in understanding the mechanisms of hepatic fibrosis. Major advances include: (i) characterization of the components of extracellular matrix (ECM) in normal and fibrotic liver; (ii) identification of hepatic stellate cells as the primary source of ECM in liver fibrosis; (iii) elucidation of key cytokines, their cellular sources, modes of regulation, and signalling pathways involved in liver fibrogenesis; (iv) characterization of key matrix proteases and their inhibitors; (v) identification of apoptotic mediators in stellate cells and exploration of their roles during the resolution of liver injury. These advances have helped delineate a more comprehensive picture of liver fibrosis in which the central event is the activation of stellate cells, a transformation from quiescent vitamin A-rich cells to proliferative, fibrogenic and contractile myofibroblasts. The progress in understanding fibrogenic mechanisms brings the development of effective therapies closer to reality. In the future, targeting of stellate cells and fibrogenic mediators will be a mainstay of antifibrotic therapy. Points of therapeutic intervention may include: (i) removing the injurious stimuli; (ii) suppressing hepatic inflammation; (iii) down-regulating stellate cell activation; and (iv) promoting matrix degradation. The future prospects for effective antifibrotic treatment are more promising than ever for the millions of patients with chronic liver disease worldwide.

Albumin modified with mannose 6-phosphate: A potential carrier for selective delivery of antifibrotic drugs to rat and human hepatic stellate cells

The hallmark of liver fibrosis is an increased extracellular matrix deposition, caused by an activation of hepatic stellate cells (HSC). Therefore, this cell type is an important target for pharmacotherapeutic intervention. Antifibrotic drugs are not efficiently taken up by HSC or may produce unwanted side-effects outside the liver. Cell-specific delivery can provide a solution to these problems, but a specific drug carrier for HSC has not been described until now. The mannose 6-phosphate/insulin-like growth factor II (M6P/IGF-II) receptor, which is expressed in particular upon HSC during fibrosis, may serve as a target-receptor for a potential carrier. The aim of the present study was to examine if human serum albumin (HSA) modified with mannose 6-phosphate (M6P) is taken up by HSC in fibrotic livers. A series of M6Px-modified albumins were synthetized: x = 2, 4, 10, and 28. Organ distribution studies were performed to determine total liver uptake. The hepatic uptake of M6Px-HSA increased with increasing M6P density. M6Px-HSA with a low degree of sugar loading (x = 2-10) remained in the plasma and accumulated for 9% +/- 0.5% or less in fibrotic rat livers. An increase in the molar ratio of M6P:HSA to 28:1 caused an increased liver accumulation to 59% +/- 9% of the administered dose. Furthermore, we determined quantitatively the in vivo intrahepatic distribution of M6Px-HSA using double-immunostaining techniques. An increased substitution of M6P was associated with an increased accumulation in HSC; 70% +/- 11% of the intrahepatic staining for M6P28-HSA was found in HSC. We also demonstrate that M6P-modified bovine serum albumin (BSA) accumulates in slices of normal and cirrhotic human livers. After incubation of this neoglycoprotein with human tissue, the protein is found in nonparenchymal liver cells. Because M6P-modified albumins are taken up by HSC in fibrotic livers, this neoglycoprotein can be applied as a selective drug carrier for HSC. This technology may create new opportunities for the pharmacological intervention of liver fibrosis.

Effect of pentoxifylline on early proliferation and phenotypic modulation of fibrogenic cells in two rat models of liver fibrosis and on cultured hepatic stellate cells

BACKGROUND/AIMS

During liver fibrosis, different fibroblastic cells, i.e. hepatic stellate cells (HSCs) or portal fibroblasts, are involved in the development of lesions, and acquire myofibroblastic differentiation. We investigated, in the rat, whether pentoxifylline can influence the early phase of fibrogenesis in two animal models of fibrosis induced by either carbon tetrachloride (CCl4) plus acetone (given twice) or bile duct ligation.

METHODS

The fibroproliferative response and myofibroblastic phenotypic modulation were evaluated by PCNA and alpha-smooth muscle (alpha-SM) actin immunohistochemistry, respectively, in livers taken 24 h after the last CCl4 treatment or 72 h after bile duct ligation. Desmin expression was also measured, and inflammation was evaluated by ED-1 staining. Furthermore, proliferation and alpha-SM actin expression were studied in cultured HSCs after pentoxifylline treatment.

RESULTS

In the CCl4-acetone groups, pretreatment with pentoxifylline decreased the proliferative response and expression of alpha-SM actin in the HSCs. Similarly, pentoxifylline reduced the proliferation and myofibroblastic differentiation of portal fibroblasts after bile duct ligation. Pentoxifylline reduced ED-1 expression, particularly in the CCl4 model, where there was significant inflammation. In cultured pentoxifylline-treated HSCs, both proliferation and alpha-SM actin expression were decreased.

CONCLUSIONS

In both animal models of fibrosis, during the early stages of tissue injury, pentoxifylline was able to reduce fibroproliferation and myofibroblastic differentiation and to reduce hepatocellular damage and the inflammatory response, particularly in the toxin-induced model. In culture, alpha-SM actin expression decreased in both growing and quiescent HSCs treated with pentoxifylline, indicating that the drug may also exert a direct effect on hepatic fibrogenic cells.