Low molecular weight heparin prevents hepatic fibrogenesis caused by carbon tetrachloride in the rat

Poly(ethylene glycol) Hydrogels with the Sustained Release of Hepatocyte Growth Factor for Enhancing Vascular Regeneration

The surface modification of biologically active factors on tissue-engineering vascular scaffold fails to fulfill the mechanical property and bioactive compounds' sustained release in vivo and results in the inhibition of tissue regeneration of small-diameter vascular grafts in vascular replacement therapies. In this study, biodegradable poly(ε-caprolactone) (PCL) was applied for scaffold preparation, and poly(ethylene glycol) (PG) hydrogel was used to load heparin and hepatocyte growth factor (HGF). In vitro analysis demonstrated that the PCL scaffold could inhibit the heparin release from the PG hydrogel, and the PG hydrogel could inhibit heparin release during the process of PCL degradation. Finally, it results in sustained release of HGF and heparin from the PCL-PG-HGF scaffold. The mechanical property of this hybrid scaffold improved after being coated with the PG hydrogel. In addition, the PCL-PG-HGF scaffold illustrated no inflammatory lesions, organ damage, or biological toxicity in all primary organs, with rapid organization of the endothelial cell layer, smooth muscle regeneration, and extracellular matrix formation. These results indicated that the PCL-PG-HGF scaffold is biocompatible and provides a microenvironment in which a tissue-engineered vascular graft with anticoagulant properties allows regeneration of vascular tissue (Scheme 1). Such findings confirm the feasibility of creating hydrogel scaffolds coated with bioactive factors to prepare novel vascular grafts.

The implication of neutrophil extracellular traps in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is an expanding worldwide health concern, and the underlying mechanisms contributing to its progression still need further exploration. Neutrophil extracellular traps (NETs) are intricate formations comprised of nuclear constituents and diverse antimicrobial granules that are released into the extracellular milieu by activated neutrophils upon various triggers, which play a pivotal part in the onset and advancement of NAFLD. NETs actively participate in the genesis of NAFLD by fostering oxidative stress and inflammation, ultimately resulting in hepatic fat accumulation and the escalation of liver injury. Recent insights into the interaction with other hepatic immune populations and mediators, such as macrophages and T regulatory cells, have revealed several important mechanisms that can trigger further liver injury. In conclusion, the formation of NETs emerged as an important factor in the development of NAFLD, offering a promising target for innovative therapeutic approaches against this debilitating condition. This comprehensive review seeks to compile existing studies exploring the involvement of NETs in the genesis of NAFLD and their influence on the immune response throughout the progression of NAFLD.

Molecular Mechanisms Underlying Vascular Liver Diseases: Focus on Thrombosis

Vascular liver disorders (VLDs) comprise a wide spectrum of clinical-pathological entities that primarily affect the hepatic vascular system of both cirrhotic and non-cirrhotic patients. VLDs more frequently involve the portal and the hepatic veins, as well as liver sinusoids, resulting in an imbalance of liver homeostasis with serious consequences, such as the development of portal hypertension and liver fibrosis. Surprisingly, many VLDs are characterized by a prothrombotic phenotype. The molecular mechanisms that cause thrombosis in VLD are only partially explained by the alteration in the Virchow's triad (hypercoagulability, blood stasis, and endothelial damage) and nowadays their pathogenesis is incompletely described and understood. Studies about this topic have been hampered by the low incidence of VLDs in the general population and by the absence of suitable animal models. Recently, the role of coagulation imbalance in liver disease has been postulated as one of the main mechanisms linked to fibrogenesis, so a novel interest in vascular alterations of the liver has been renewed. This review provides a detailed analysis of the current knowledge of molecular mechanisms of VLD. We also focus on the promising role of anticoagulation as a strategy to prevent liver complications and to improve the outcome of these patients.

Microvascular Thrombosis and Liver Fibrosis Progression: Mechanisms and Clinical Applications

Fibrosis is an unavoidable consequence of chronic inflammation. Extracellular matrix deposition by fibroblasts, stimulated by multiple pathways, is the first step in the onset of chronic liver disease, and its propagation promotes liver dysfunction. At the same time, chronic liver disease is characterized by alterations in primary and secondary hemostasis but unlike previously thought, these changes are not associated with an increased risk of bleeding complications. In recent years, the role of coagulation imbalance has been postulated as one of the main mechanisms promoting hepatic fibrogenesis. In this review, we aim to investigate the function of microvascular thrombosis in the progression of liver disease and highlight the molecular and cellular networks linking hemostasis to fibrosis in this context. We analyze the predictive and prognostic role of coagulation products as biomarkers of liver decompensation (ascites, variceal hemorrhage, and hepatic encephalopathy) and liver-related mortality. Finally, we evaluate the current evidence on the application of antiplatelet and anticoagulant therapies for prophylaxis of hepatic decompensation or prevention of the progression of liver fibrosis.

The effect of intraurethral heparin on inflammation and spongiofibrosis in a rat model of experimentally induced urethral trauma

AIM

To determine the effect of heparin administered during the early post urethral trauma period on inflammation and spongiofibrosis in rats.

MATERIALS AND METHODS

The study included 24 male rats that were randomized into 3 groups of 8 each. The urethra was traumatized using a 24-G needle sheath in all rats. Group 1 (control group) received intraurethral saline 0.9% injected b.i.d. for 27 days, group 2 received intraurethral Na-heparin (liquemine-Roche) 1500 IU kg^-1 injected b.i.d. for 27 days, and group 3 received intraurethral Na-heparin 1500 IU kg^-1 injected b.i.d and saline 0.9% s.i.d. for 27 days. On day 28 the rats' penises were degloved and penectomy was performed. Inflammation, spongiofibrosis, and congestion in the urethra were investigated in each group.

RESULTS

A statistically significant difference was found between the three groups (control, heparin, and heparin + saline) in the histopathological status of spongiofibrosis, inflammation, and congestion, respectively (P = 0.0001, P = 0.002, P = 0.0001). Severe spongiofibrosis was observed in six (75%) of the rats in group 1 (control group), whereas severe spongiofibrosis was not observed in group 2 (heparin) or group 3 (heparin + saline).

CONCLUSION

We observed that intraurethral Na-heparin 1500 IU kg^-1 injectioned during the early posturethral trauma period in rats significantly decreased inflammation, spongiofibrosis, and congestion.

Improving Management of Portal Hypertension: The Potential Benefit of Non-Etiological Therapies in Cirrhosis

Portal hypertension is the consequence of cirrhosis and results from increased sinusoidal vascular resistance and hepatic blood inflow. Etiological therapies represent the first intervention to prevent a significant increase in portal pressure due to chronic liver damage. However, other superimposed pathophysiological drivers may worsen liver disease, including inflammation, bacterial translocation, endothelial dysfunction, and hyperactivation of hemostasis. These mechanisms can be targeted by a specific class of drugs already used in clinical practice. Albumin, rifaximin, statins, aspirin, and anticoagulants have been tested in cirrhosis and were a topic of discussion in the last Baveno consensus as non-etiological therapies. Based on the pathogenesis of portal hypertension in cirrhosis, our review summarizes the main mechanisms targeted by these drugs as well as the clinical evidence that considers them a valid complementary option to manage patients with cirrhosis and portal hypertension.

The beneficial role of Hepcidin peptide inhibitor in improved the symptoms of COVID-19 in diabetics: anti-inflammatory and potential therapeutic effects

Coronavirus Disease 2019 (COVID-19) is a recent public health issue worldwide. Also, diabetes is a frequent condition with high mortality. There is a strong relationship between COVID-19 and diabetes. This article analyses the intricate relationship between COVID-19 and hepcidin. Hepcidin increases in aged non-insulin diabetic patients. Hepcidin is the last target treatment of several medications commonly used. Viral diseases, especially SARS-CoV19, can activate the hepcidin pathway leading to an elevation in the iron load. This increased iron is released into the bloodstream and results in cell death through ferroptosis, like free iron. Excess iron has pro-coagulative and toxic effects. Hepcidin overexpression and iron overload are associated with COVID-19 infection and can be considered potential targets for treatment. Several studies have shown dalteparin (anti-Hepcidin) could improve the symptoms of COVID-19 in diabetics by appropriately modulating and decreasing oxidative stress and inflammation. This finding can be leading to enhancing the existing knowledge about Therapeutic measures for reducing Covid-19 impairments in diabetics and is suggested as a possible therapeutic agent in diabetes.

Investigational drugs in early clinical development for portal hypertension

INTRODUCTION

Advanced chronic liver disease is considered a reversible condition after removal of the primary aetiological factor. This has led to a paradigm shift in which portal hypertension (PH) is a reversible complication of cirrhosis. The pharmacologic management of PH is centered on finding targets to modify the natural history of cirrhosis and PH.

AREAS COVERED

This paper offers an overview of the use of pharmacological strategies in early clinical development that modify PH. Papers included were selected from searching clinical trials sites and PubMed from the last 10 years.

EXPERT OPINION

A paradigm shift has generated a new concept of PH in cirrhosis as a reversible complication of a potentially curable disease. Decreasing portal pressure to prevent decompensation and further complications of cirrhosis that may lead liver transplantation or death is a goal. Therapeutic strategies also aspire achieve total or partial regression of fibrosis thus eliminating the need for treatment or screening of PH.

The Therapeutic Potential of Anticoagulation in Organ Fibrosis

Fibrosis, also known as organ scarring, describes a pathological stiffening of organs or tissues caused by increased synthesis of extracellular matrix (ECM) components. In the past decades, mounting evidence has accumulated showing that the coagulation cascade is directly associated with fibrotic development. Recent findings suggest that, under inflammatory conditions, various cell types (e.g., immune cells) participate in the coagulation process causing pathological outcomes, including fibrosis. These findings highlighted the potential of anticoagulation therapy as a strategy in organ fibrosis. Indeed, preclinical and clinical studies demonstrated that the inhibition of blood coagulation is a potential intervention for the treatment of fibrosis across all major organs (e.g., lung, liver, heart, and kidney). In this review, we aim to summarize our current knowledge on the impact of components of coagulation cascade on fibrosis of various organs and provide an update on the current development of anticoagulation therapy for fibrosis.

Von Willebrand factor exerts hepatoprotective effects in acute but not chronic cholestatic liver injury in mice

Acute and chronic liver disease are associated with substantial alterations in the hemostatic system, including elevated levels of the platelet-adhesive protein von Willebrand factor (VWF). Carbon tetrachloride-induced liver fibrosis is reduced in VWF-deficient mice, but it is unclear if VWF plays a pathologic role in all settings of liver fibrosis. Indeed, several studies suggest an anti-fibrotic role for components of the hemostatic system, including platelets, in experimental settings of bile duct fibrosis. However, the role of VWF in this specific pathology has not been examined. We tested the hypothesis that VWF exerts hepatoprotective effects in experimental bile duct injury. Wild-type and VWF-deficient (VWF^-/-) mice were challenged with the bile duct toxicant alpha-naphthylisothiocyanate (ANIT) and the impact of VWF deficiency on acute cholestatic liver injury and chronic liver fibrosis was determined. Acute ANIT (60 mg/kg, po)-induced cholestatic liver injury was associated with increased VWF plasma antigen and activity levels. VWF deficiency enhanced ANIT-induced hepatocellular injury, evidenced by increased plasma ALT activity and area of hepatocellular necrosis. Surprisingly, platelet accumulation within necrotic areas was increased in ANIT-challenged VWF^-/- mice compared to wild-type mice. Compared to acute ANIT challenge, hepatic platelet accumulation was modest and appeared to be VWF-dependent in mice exposed to ANIT diet (0.05 %) for 6 weeks. However, contrasting the role of VWF after acute ANIT challenge, VWF deficiency did not impact biliary fibrosis induced by chronic ANIT exposure. The results suggest that VWF plays dichotomous roles in experimental acute and chronic ANIT-induced cholestatic liver injury.

Sulfatase-2 Regulates Liver Fibrosis through the TGF-β Signaling Pathway

Transforming growth factor-β (TGF-β) activates hepatic stellate cells (HSCs), which drive liver fibrosis via the production and deposition of extracellular matrix (ECM). We aimed to elucidate the mechanistic role of sulfatase-2 (SULF2) in liver fibrosis. To this end, we induced liver fibrosis in wild-type (WT) and SULF2 knockout (Sulf2-KO) mice (6-8 weeks-old) via bile duct ligation (BDL), intraperitoneal injection of carbon tetrachloride (CCl₄) or thioacetamide (TAA). The levels of fibrosis in the liver sections were assessed via Sirius red and Masson's trichrome staining, immunohistochemistry and immunoblotting for α-smooth muscle actin (α-SMA) and hydroxyproline. To evaluate the interaction between TGF-β and SULF2, we transfected human HSCs with scrambled control shRNA and shRNA constructs targeting SULF2 and measured α-SMA expression following treatment with TGF-β1 ligand. We show here that knockout of SULF2 significantly decreases collagen content, as well as bands of bridging fibrosis, as demonstrated by Sirius red, Masson's trichrome and α-SMA staining after BDL, CCl₄ and TAA injection in Sulf2-KO versus WT mice. In all three models of liver fibrosis, we observed significantly lower levels of hydroxyproline in the Sulf2-KO mice compared to the WT mice. HSCs with reduced levels of SULF2 failed to significantly express α-SMA and collagen type I following treatment with TGF-β1. Furthermore, SULF2 co-localizes with TGFBR3 and the in vitro knockdown of SULF2 in HSCs decreases the release of TGF-β1 from TGFBR3. Together, these data suggest that SULF2 regulates liver fibrosis via the TGF-β signaling pathway. Pharmacologic inhibition of SULF2 may represent a novel therapeutic approach to improve liver fibrosis.

Portal hypertension in cirrhosis: Pathophysiological mechanisms and therapy

Portal hypertension, defined as increased pressure in the portal vein, develops as a consequence of increased intrahepatic vascular resistance due to the dysregulation of liver sinusoidal endothelial cells (LSECs) and hepatic stellate cells (HSCs), frequently arising from chronic liver diseases. Extrahepatic haemodynamic changes contribute to the aggravation of portal hypertension. The pathogenic complexity of portal hypertension and the unsuccessful translation of preclinical studies have impeded the development of effective therapeutics for patients with cirrhosis, while counteracting hepatic and extrahepatic mechanisms also pose a major obstacle to effective treatment. In this review article, we will discuss the following topics: i) cellular and molecular mechanisms of portal hypertension, focusing on dysregulation of LSECs, HSCs and hepatic microvascular thrombosis, as well as changes in the extrahepatic vasculature, since these are the major contributors to portal hypertension; ii) translational/clinical advances in our knowledge of portal hypertension; and iii) future directions.

Targeting von Willebrand factor in liver diseases: A novel therapeutic strategy?

Acute and chronic liver disease are associated with substantial alterations in the hemostatic system. Evidence from both experimental and clinical studies suggests that anticoagulants slow the progression of liver disease. Efficacy of those anticoagulant drugs is, in part, attributed to a reduction of microthrombi formation within the liver. Although anticoagulant drugs show promising results, bleeding risk associated with these drugs is an obvious drawback, particularly in patients with a complex coagulopathy driven by decreased liver function. Identifying therapies that reduce intrahepatic thrombosis with minimal bleeding risk would significantly advance the field. Among the hemostatic alterations observed in patients are substantially increased levels of the platelet-adhesive protein von Willebrand factor (VWF). In contrast, levels of A Disintegrin and Metalloproteinase with Thrombospondin motifs, the enzyme that regulates VWF activity, are significantly reduced in patients with liver disease. Highly elevated VWF levels are proposed to accelerate intrahepatic thrombus formation and thus be a driver of disease progression. Strong clinical evidence suggesting a link between liver disease and changes in VWF is now being matched by emerging mechanistic data showing a detrimental role for VWF in the progression of liver disease. This review focuses on clinical and experimental evidence supporting a connection between VWF function and the progression of acute and chronic liver diseases. Furthermore, with the recent anticipated approval of several novel therapies targeting VWF, we discuss potential strategies and benefits of targeting VWF as an innovative therapy for patients with liver disease.

Identification of key genes and pathways in scleral extracellular matrix remodeling in glaucoma: Potential therapeutic agents discovered using bioinformatics analysis

Background: Glaucoma is a leading cause of irreversible blindness. Remodeling of the scleral extracellular matrix (ECM) plays an important role in the development of glaucoma. The aim of this study was to identify the key genes and pathways for the ECM remodeling of sclera in glaucoma by bioinformatics analysis and to explore potential therapeutic agents for glaucoma management. Methods: Genes associated with glaucoma, sclera and ECM remodeling were detected using the text mining tool pubmed2ensembl, and assigned Gene Ontology (GO) biological process terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways using the GeneCodis program. A protein-protein interaction (PPI) network was constructed by STRING and visualized in Cytoscape, module analysis was performed using the Molecular Complex Detection (MCODE) plugin, and GO and KEGG analyses of the gene modules were performed using the Database of Annotation, Visualization and Integrated Discovery (DAVID) platform. The genes that clustered in the significant module were selected as core genes, and functions and pathways of the core genes were visualized using ClueGO and CluePedia. Lastly, the drug-gene interaction database was used to explore drug-gene interactions of the core genes to find drug candidates for glaucoma. Results: We identified 125 genes common to "Glaucoma", "Sclera", and "ECM remodeling" by text mining. Gene functional enrichment analysis yielded 30 enriched GO terms and 20 associated KEGG pathways. A PPI network that included 60 nodes with 249 edges was constructed, and three gene modules were obtained using the MCODE. We selected 13 genes that clustered in module 1 as core candidate genes that were associated mainly with ECM degradation and cell proliferation and division. The HIF-1 signaling pathway, FOXO signaling pathway, PI3K-Akt signaling pathway and TGFB signaling pathway were found to be enriched. We found that 11 of the 13 selected genes could be targeted by 26 existing drugs. Conclusions: The results showed that VEGFA, TGFB1, TGFB2, TGFB3, IGF2, IGF1, EGF, FN1, KNG1, TIMP1, SERPINE1, THBS1, and VWF were potential key genes involved to scleral ECM remodeling. Furthermore, 26 drugs were identified as potential therapeutic agents for glaucoma treatment and management.

Healing gone wrong: convergence of hemostatic pathways and liver fibrosis?

Fibrosis results from a disordered wound healing response within the liver with activated hepatic stellate cells laying down dense, collagen-rich extracellular matrix that eventually restricts liver hepatic synthetic function and causes increased sinusoidal resistance. The end result of progressive fibrosis, cirrhosis, is associated with significant morbidity and mortality as well as tremendous economic burden. Fibrosis can be conceptualized as an aberrant wound healing response analogous to a chronic ankle sprain that is driven by chronic liver injury commonly over decades. Two unique aspects of hepatic fibrosis - the chronic nature of insult required and the liver's unique ability to regenerate - give an opportunity for pharmacologic intervention to stop or slow the pace of fibrosis in patients early in the course of their liver disease. Two potential biologic mechanisms link together hemostasis and fibrosis: focal parenchymal extinction and direct stellate cell activation by thrombin and Factor Xa. Available translational research further supports the role of thrombosis in fibrosis. In this review, we will summarize what is known about the convergence of hemostatic changes and hepatic fibrosis in chronic liver disease and present current preclinical and clinical data exploring the relationship between the two. We will also present clinical trial data that underscores the potential use of anticoagulant therapy as an antifibrotic factor in liver disease.

Molecular Magnetic Resonance Imaging of Fibrin Deposition in the Liver as an Indicator of Tissue Injury and Inflammation

RATIONALE AND OBJECTIVES

Liver inflammation is associated with nonalcoholic steatohepatitis and other pathologies, but noninvasive methods to assess liver inflammation are limited. Inflammation causes endothelial disruption and leakage of plasma proteins into the interstitial space and can result in extravascular coagulation with fibrin deposition. Here we assess the feasibility of using the established fibrin-specific magnetic resonance probe EP-2104R for the noninvasive imaging of fibrin as a marker of liver inflammation.

METHODS

Weekly 100 mg/kg diethylnitrosamine (DEN) dosing was used to generate liver fibrosis in male rats; control animals received vehicle. Magnetic resonance imaging at 1.5 T with EP-2104R, a matched non-fibrin-binding control linear peptide, or the collagen-specific probe EP-3533 was performed at 1 day or 7 days after the last DEN administration. Imaging data were compared with quantitative histological measures of fibrosis and inflammation.

RESULTS

After 4 or 5 DEN administrations, the liver becomes moderately fibrotic, and fibrosis is the same if the animal is killed 1 day (Ishak score, 3.62 ± 0.31) or 7 days (Ishak score, 3.82 ± 0.25) after the last DEN dose, but inflammation is significantly higher at 1 day compared with 7 days after the last DEN dose (histological activity index from 0-4, 3.54 ± 0.14 vs 1.61 ± 0.16, respectively; P < 0.0001). Peak EP-2104R signal enhancement was significantly higher in animals imaged at 1 day post-DEN compared with 7 days post-DEN or control rats (29.0% ± 3.2% vs 22.4% ± 2.0% vs 17.0% ± 0.2%, respectively; P = 0.017). Signal enhancement with EP-2104R was significantly higher than control linear peptide at 1 day post-DEN but not at 7 days post-DEN indicating specific fibrin binding during the inflammatory phase. Collagen molecular magnetic resonance with EP-3533 showed equivalent T1 change when imaging rats 1 day or 7 days post-DEN, consistent with equivalent fibrosis.

CONCLUSIONS

EP-2104R can specifically detect fibrin associated with inflammation in a rat model of liver inflammation and fibrosis.

Effects of Anticoagulants on Experimental Models of Established Chronic Liver Diseases: A Systematic Review and Meta-Analysis

OBJECTIVE

The role of anticoagulants in chronic liver diseases is inconclusive. A meta-analysis was thus undertaken to evaluate treatment-related survival and antifibrotic effects in animal models of chronic liver diseases.

METHODS

A systematic search of the literature took place (up to November 2020), screening for preclinical studies that evaluated anticoagulant effects in animal models of chronic liver diseases. We assessed the quality of methods and the certainty of evidence. Data on outcomes were extracted and pooled into random-effects models.

RESULTS

Sixteen studies proved eligible, each assessing anticoagulant use in animals with chronic liver diseases. Generally, the pooled evidence demonstrated that the administration of anticoagulants is preventive against fibrogenesis, as indicated by METAVIR fibrosis scores (risk ratio = 0.66, 95% confidence interval: 0.47 to 0.94), portal pressure determinations (mean difference = -1.39, 95% confidence interval: -2.33 to -0.44), inflammatory activity (mean difference = -169.69, 95% confidence interval: -257.64 to -81.74), and indices of hepatic injury, specifically alanine aminotransferase (mean difference = -82.7, 95% confidence interval: -107.36 to -58.04), aspartate aminotransferase (mean difference = -186.12, 95% confidence interval: -254.90 to -117.33), albumin (mean difference = 0.59, 95% confidence interval: 0.16 to 1.01), and total bilirubin (mean difference = -0.96, 95% confidence interval: -1.46 to -0.46), and it had no impact on animal survival (risk ratio = 1.03, 95% confidence interval: 0.94 to 1.13).

CONCLUSIONS

Our assessments indicate that in animal models of chronic liver diseases, anticoagulants may alleviate the degree of fibrosis evaluated by the METAVIR score system, portal pressure, inflammatory activity, and serum indices of hepatocellular injury, without impacting survival. High-quality experimental studies are still required.

Congestive Hepatopathy

Liver disease resulting from heart failure (HF) has generally been referred as “cardiac hepatopathy”. One of its main forms is congestive hepatopathy (CH), which results from passive venous congestion in the setting of chronic right-sided HF. The current spectrum of CH differs from earlier reports with HF, due to ischemic cardiomyopathy and congenital heart disease having surpassed rheumatic valvular disease. The chronic passive congestion leads to sinusoidal hypertension, centrilobular fibrosis, and ultimately, cirrhosis (“cardiac cirrhosis”) and hepatocellular carcinoma after several decades of ongoing injury. Contrary to primary liver diseases, in CH, inflammation seems to play no role in the progression of liver fibrosis, bridging fibrosis occurs between central veins to produce a “reversed lobulation” pattern and the performance of non-invasive diagnostic tests of liver fibrosis is poor. Although the clinical picture and prognosis is usually dominated by the underlying heart condition, the improved long-term survival of cardiac patients due to advances in medical and surgical treatments are responsible for the increased number of liver complications in this setting. Eventually, liver disease could become as clinically relevant as cardiac disease and further complicate its management.

Localized inhibition of platelets and platelet derived growth factor by a matrix targeted glycan mimetic significantly attenuates liver fibrosis

New therapeutic strategies are needed for the growing unmet clinical needs in liver disease and fibrosis. Platelet activation and PDGF activity are recognized as important therapeutic targets; however, no therapeutic approach has yet addressed these two upstream drivers of liver fibrosis. We therefore designed a matrix-targeting glycan therapeutic, SBR-294, to inhibit collagen-mediated platelet activation while also inhibiting PDGF activity. Herein we describe the synthesis and characterization of SBR-294 and demonstrate its potential therapeutic benefits in vitro and in vivo. In vitro SBR-294 was found to bind collagen (EC₅₀ = 23 nM), thereby inhibiting platelet-collagen engagement (IC₅₀ = 60 nM). Additionally, SBR-294 was found to bind all PDGF homodimeric isoforms and to inhibit PDGF-BB mediated hepatic stellate cell activation and proliferation. Translating these mechanisms in vivo, SBR-294 reduced fibrosis by up to 54% in the CCl4 mouse model (p = 0.0004), as measured by Sirius red histological analysis. Additional fibrosis measurements were also supportive of the therapeutic benefit in this model. These results support the therapeutic benefit of platelet and PDGF antagonism and warrant further investigation of SBR-294 as a potential treatment for liver fibrosis.

Antifibrotic therapy by sustained release of low molecular weight heparin from poly(lactic-co-glycolic acid) microparticles on bleomycin-induced pulmonary fibrosis in mice

Heparin and low molecular weight heparin (LMWH) have recently been considered useful treatment tools for inflammation. Heparin has antifibrotic activity, mediated by cellular secretion of hepatocyte growth factor (HGF). HGF has antifibrotic properties demonstrated in experimental models of lung, kidney, heart, skin, and liver fibrosis. The ability of LMWH for HGF secretion is similar to that of normal heparin. Poly (lactic-co-glycolic acid) (PLGA) is widely used for sustained drug release, because of its biocompatibility and low toxicity. LMWH-loaded PLGA microparticles are prepared by a conventional water-in-oil-in-water emulsion method. Interstitial pneumonia is a life-threatening pathological condition that causes respiratory failure when it progresses. In the present study, we investigated the therapeutic effect of LMWH-loaded PLGA microparticles in a mouse model of bleomycin-induced lung fibrosis. The ratios of fibrotic area to total area were significantly lower in mice administered LMWH-loaded microparticles than in mice administered bleomycin alone. The microparticle administration did not further enhance the gene expression for inflammatory cytokines. In a cell culture study, HGF secretion by mouse and human lung fibroblasts was significantly increased by LMWH addition. We conclude that LMWH showed anti-inflammatory activity, through the effects of LMWH-loaded PLGA microparticles on cells at sites of inflammation.

Liver fibrosis is driven by protease-activated receptor-1 expressed by hepatic stellate cells in experimental chronic liver injury

BACKGROUND

Blood coagulation protease activity is proposed to drive hepatic fibrosis through activation of protease-activated receptors (PARs). Whole-body PAR-1 deficiency reduces experimental hepatic fibrosis, and in vitro studies suggest a potential contribution by PAR-1 expressed by hepatic stellate cells. However, owing to a lack of specific tools, the cell-specific role of PAR-1 in experimental hepatic fibrosis has never been formally investigated. Using a novel mouse expressing a conditional PAR-1 allele, we tested the hypothesis that PAR-1 expressed by hepatic stellate cells contributes to hepatic fibrosis.

METHODS

PAR-1flox/flox mice were crossed with mice expressing Cre recombinase controlled by the lecithin retinol acyltransferase (LRAT) promoter, which induces recombination in hepatic stellate cells. Male PAR-1flox/flox/LRATCre and PAR-1flox/flox mice were challenged twice weekly with carbon tetrachloride (CCl4, 1 mL/kg i.p.) for 6 weeks to induce liver fibrosis.

RESULTS

PAR-1 mRNA levels were reduced (>95%) in hepatic stellate cells isolated from PAR-1flox/flox/LRATCre mice. Hepatic stellate cell activation was evident in CCl4-challenged PAR-1flox/flox mice, indicated by increased α-smooth muscle actin labeling and induction of several profibrogenic genes. CCl4-challenged PAR-1flox/flox mice displayed robust hepatic collagen deposition, indicated by picrosirius red staining and type I collagen immunolabeling. Notably, stellate cell activation and collagen deposition were significantly reduced (>30%) in PAR-1flox/flox/LRATCre mice. Importantly, the reduction in liver fibrosis was not a consequence of reduced acute CCl4 hepatotoxicity in PAR-1flox/flox/LRATCre mice.

CONCLUSIONS

The results constitute the first direct experimental evidence that PAR-1 expressed by stellate cells directly promotes their profibrogenic phenotype and hepatic fibrosis in vivo.

Portal vein thrombosis in cirrhosis: Why a well-known complication is still matter of debate

Portal vein thrombosis (PVT) represents a well-known complication during the natural course of liver cirrhosis (LC), ranging from asymptomatic cases to life-threating conditions related to portal hypertension and hepatic decompensation. Portal flow stasis, complex acquired hypercoagulable disorders and exogenous factors leading to endothelial dysfunction have emerged as key factors for PVT development. However, PVT occurrence remains unpredictable and many issues regarding its natural history, prognostic significance and treatment are still elusive. In particular although spontaneous resolution or disease stability occur in most cases of PVT, factors predisposing to disease progression or recurrence after spontaneous recanalization are not clarified as yet. Moreover, PVT impact on LC outcome is still debated, as PVT may represent itself a consequence of liver fibrosis and hepatic dysfunction progression. Anticoagulation and transjugular intrahepatic portosystemic shunt are considered safe and effective in this setting and are recommended in selected cases, even if the safer therapeutic option and the optimal therapy duration are still unknown. Nevertheless, their impact on mortality rates should be addressed more extensively. In this review we present the most debated questions regarding PVT, whose answers should come from prospective cohort studies and large sample-size randomized trials.

Chronic liver injury drives non-traditional intrahepatic fibrin(ogen) crosslinking via tissue transglutaminase

Essentials Fibrin clots are often implicated in the progression of liver fibrosis. Liver fibrosis was induced in transgenic mice with defects in clot formation or stabilization. Liver fibrosis and fibrin(ogen) deposition do not require fibrin polymerization or factor XIIIa. Fibrin(ogen) is an in vivo substrate of tissue transglutaminase in experimental liver fibrosis. SUMMARY: Background Intravascular fibrin clots and extravascular fibrin deposits are often implicated in the progression of liver fibrosis. However, evidence supporting a pathological role of fibrin in hepatic fibrosis is indirect and based largely on studies using anticoagulant drugs that inhibit activation of the coagulation protease thrombin, which has other downstream targets that promote fibrosis. Therefore, the goal of this study was to determine the precise role of fibrin deposits in experimental hepatic fibrosis. Methods Liver fibrosis was induced in mice expressing mutant fibrinogen insensitive to thrombin-mediated proteolysis (i.e. locked in the monomeric form), termed FibAEK mice, and factor XIII A2 subunit-deficient (FXIII-/- ) mice. Female wild-type mice, FXIII-/- mice and homozygous FibAEK mice were challenged with carbon tetrachloride (CCl4 ) twice weekly for 4 weeks or 6 weeks (1 mL kg-1 , intraperitoneal). Results Hepatic injury and fibrosis induced by CCl4 challenge were unaffected by FXIII deficiency or inhibition of thrombin-catalyzed fibrin polymer formation (in FibAEK mice). Surprisingly, hepatic deposition of crosslinked fibrin(ogen) was not reduced in CCl4 -challenged FXIII-/- mice or FibAEK mice as compared with wild-type mice. Rather, deposition of crosslinked hepatic fibrin(ogen) following CCl4 challenge was dramatically reduced in tissue transglutaminase-2 (TGM2)-deficient (TGM2-/- ) mice. However, the reduction in crosslinked fibrin(ogen) in TGM2-/- mice did not affect CCl4 -induced liver fibrosis. Conclusions These results indicate that neither traditional fibrin clots, formed by the thrombin-activated FXIII pathway nor atypical TGM2-crosslinked fibrin(ogen) contribute to experimental CCl4 -induced liver fibrosis. Collectively, the results indicate that liver fibrosis occurs independently of intrahepatic fibrin(ogen) deposition.

Anticoagulation and Transjugular Intrahepatic Portosystemic Shunting for Treatment of Portal Vein Thrombosis in Cirrhosis: A Systematic Review and Meta-Analysis

Portal vein thromboses (PVTs) are associated with hepatic decompensation, worse survival, and worse liver transplant outcomes. We evaluated the impact of anticoagulation (AC) and transjugular intrahepatic portosystemic shunting (TIPS) on recanalization and mortality in patients with cirrhosis and PVT. Systematic search of electronic databases was performed. Clinical trials and observational studies that evaluated primary outcomes of recanalization and survival in patients with cirrhosis having PVT treated with AC or TIPS were included. Risk of bias was assessed. Summary odds ratios (ORs) for pooled data from the included studies were generated using a random effects model. A total of 505 studies were screened for inclusion. After review, 7 studies were ultimately included. Data from 327 patients in total were evaluated. Overall, treatment with either AC or TIPS resulted in partial or complete recanalization (OR: 4.56 [95% confidence interval, CI: 2.46-8.47]) but did not significantly impact mortality (OR: 0.57 [95% CI: 0.21-1.57]). The summary OR of AC for recanalization was 6.00 (95% CI: 2.38-15.07). The summary OR of TIPS for recanalization was 3.80 (95% CI: 1.47-9.83). The summary OR of mortality in patients treated with AC for PVT was 0.28 (95% CI: 0.08-0.95). The mortality summary OR was 1.10 (95% CI 0.23-5.16) in patients who underwent TIPS. There was insufficient data to assess complications such as hepatic encephalopathy or bleeding. Both AC and TIPS have a significant effect on recanalization. Anticoagulation appears to have a protective effect on mortality that is not seen with TIPS. More studies with control groups are need.

Role of the blood coagulation cascade in hepatic fibrosis

Liver is the primary source of numerous proteins that are critical for normal function of the blood coagulation cascade. Because of this, diseases of the liver, particularly when affiliated with severe complications like cirrhosis, are associated with abnormalities of blood clotting. Although conventional interpretation has inferred cirrhosis as a disorder of uniform bleeding risk, it is now increasingly appreciated as a disease wherein the coagulation cascade is precariously rebalanced. Moreover, prothrombotic risk factors are also associated with a more rapid progression of fibrosis in humans, suggesting that coagulation proteases participate in disease pathogenesis. Indeed, strong evidence drawn from experimental animal studies indicates that components of the coagulation cascade, particularly coagulation factor Xa and thrombin, drive profibrogenic events, leading to hepatic fibrosis. Here, we concisely review the evidence supporting a pathologic role for coagulation in the development of liver fibrosis and the potential mechanisms involved. Further, we highlight how studies in experimental animals may shed light on emerging clinical evidence, suggesting that beneficial effects of anticoagulation could extend beyond preventing thrombotic complications to include reducing pathologies like fibrosis.

Coagulation, Microenvironment and Liver Fibrosis

Fibrosis is the main consequence of any kind of chronic liver damage. Coagulation and thrombin generation are crucial in the physiological response to tissue injury; however, the inappropriate and uncontrolled activation of coagulation cascade may lead to fibrosis development due to the involvement of several cellular types and biochemical pathways in response to thrombin generation. In the liver, hepatic stellate cells and sinusoidal endothelial cells orchestrate fibrogenic response to chronic damage. Thrombin interacts with these cytotypes mainly through protease-activated receptors (PARs), which are expressed by endothelium, platelets and hepatic stellate cells. This review focuses on the impact of coagulation in liver fibrogenesis, describes receptors and pathways involved and explores the potential antifibrotic properties of drugs active in hemostasis in studies with cells, animal models of liver damage and humans.

The Role of Anticoagulation in Treating Portal Hypertension

PURPOSE OF REVIEW

To revise experimental and clinical data supporting a less traditional role of anticoagulation for treating portal hypertension in patients with cirrhosis.

RECENT FINDINGS

Portal hypertension is the main driver of complications such as ascites, variceal hemorrhage, and hepatic encephalopathy, with inflammation as a key component. The traditional view of cirrhosis as a pro-hemorrhagic condition has recently changed, prothrombotic complications being recognized as frequently as the hemorrhagic ones. Several data indicate a close relationship between inflammation, prothrombotic status, worsening of hepatic fibrosis, and portal hypertension both in animal models and in patients with chronic liver disease. These findings indicate that anticoagulation may represent a potent tool to act on fibrogenesis and therefore consequently to treat portal hypertension. All anticoagulants have good to optimal safety profiles and can be used in patients with advanced chronic liver disease with confidence.

SUMMARY

Anticoagulation has a role as a pleiotropic treatment of portal hypertension in cirrhosis.

Enoxaparin pretreatment effect on local and systemic inflammation biomarkers in the animal burn model

Low-molecular weight heparins (LMWH) are anticoagulants that have shown anti-inflammatory activity in several experimental models. Hot water burn inflammatory model accurately simulates human clinical situations allowing its use for nociception test and evaluation of anti-inflammatory drugs. The present study aims to evaluate the enoxaparin pretreatment on local and systemic inflammation biomarkers in the animal burn model. Inflammation was induced by submersing the rat left hind paw in water at 60^o C for 60 s. C-reactive protein (CRP) and thrombin-antithrombin complex (TAT) were estimated by immunosorbent assay, fibrinogen (Fg) by the gravimetric method and paw oedema by orthogonal digital photography. Highest values of paw oedema, CRP and TAT were observed at 4 h post-burn while Fg peak occurs at 12 h post-burn; enoxaparin pretreatment decreased oedema (- 32.1%), and concentration of TAT (- 66.7%), PCR (- 37.9%) and Fg (- 8%). This study shows that enoxaparin has local and systemic anti-inflammatory effects and should be considered as a potential adjuvant drug for the treatment of burns.

Biology of portal hypertension

Portal hypertension develops as a result of increased intrahepatic vascular resistance often caused by chronic liver disease that leads to structural distortion by fibrosis, microvascular thrombosis, dysfunction of liver sinusoidal endothelial cells (LSECs), and hepatic stellate cell (HSC) activation. While the basic mechanisms of LSEC and HSC dysregulation have been extensively studied, the role of microvascular thrombosis and platelet function in the pathogenesis of portal hypertension remains to be clearly characterized. As a secondary event, portal hypertension results in splanchnic and systemic arterial vasodilation, leading to the development of a hyperdynamic circulatory syndrome and subsequently to clinically devastating complications including gastroesophageal varices and variceal hemorrhage, hepatic encephalopathy from the formation of portosystemic shunts, ascites, and renal failure due to the hepatorenal syndrome. This review article discusses: (1) mechanisms of sinusoidal portal hypertension, focusing on HSC and LSEC biology, pathological angiogenesis, and the role of microvascular thrombosis and platelets, (2) the mesenteric vasculature in portal hypertension, and (3) future directions for vascular biology research in portal hypertension.

Enoxaparin does not ameliorate liver fibrosis or portal hypertension in rats with advanced cirrhosis

BACKGROUND & AIMS

Recent studies suggest that heparins reduce liver fibrosis and the risk of decompensation of liver disease. Here, we evaluated the effects of enoxaparin in several experimental models of advanced cirrhosis.

METHODS

Cirrhosis was induced in male Sprague-Dawley (SD) rats by: (i) Oral gavage with carbon tetrachloride (CCl4_ORAL ), (ii) Bile duct ligation (BDL) and (iii) CCl4 inhalation (CCl4_INH ). Rats received saline or enoxaparin s.c. (40 IU/Kg/d or 180 IU/Kg/d) following various protocols. Blood biochemical parameters, liver fibrosis, endothelium- and fibrosis-related genes, portal pressure, splenomegaly, bacterial translocation, systemic inflammation and survival were evaluated. Endothelial dysfunction was assessed by in situ bivascular liver perfusions.

RESULTS

Enoxaparin did not ameliorate liver function, liver fibrosis, profibrogenic gene expression, portal hypertension, splenomegaly, ascites development and infection, serum IL-6 levels or survival in rats with CCl4_ORAL or BDL-induced cirrhosis. Contrarily, enoxaparin worsened portal pressure in BDL rats and decreased survival in CCl4_ORAL rats. In CCl4_INH rats, enoxaparin had no effects on hepatic endothelial dysfunction, except for correcting the hepatic arterial dysfunction when enoxaparin was started with the CCl4 exposure. In these rats, however, enoxaparin increased liver fibrosis and the absolute values of portal venous and sinusoidal resistance.

CONCLUSIONS

Our results do not support a role of enoxaparin for improving liver fibrosis, portal hypertension or endothelial dysfunction in active disease at advanced stages of cirrhosis. These disease-related factors and the possibility of a limited therapeutic window should be considered in future studies evaluating the use of anticoagulants in cirrhosis.

Bleeding Risk with Invasive Procedures in Patients with Cirrhosis and Coagulopathy

PURPOSE OF REVIEW

Previous perceptions of cirrhosis as a hypocoagulable state have resulted in empirical blood product transfusions prior to invasive procedures. We evaluate procedure-related bleeding risks in patients with cirrhosis, assess the utility of conventional and newer global coagulation tests, and explore evidence surrounding prophylactic transfusion strategies.

RECENT FINDINGS

Recent literature supports the concept of a rebalanced, albeit fragile, haemostasis equilibrium in cirrhosis, with a potential hypercoagulable tendency in stable patients. Standard coagulation tests provide a poor reflection of bleeding risks and yet are relied upon for transfusion thresholds. Consequently, a sizeable proportion of patients receive unnecessary blood products. The role of viscoelastic tests to guide transfusions requires further evaluation. In stable cirrhotic patients, procedure-related bleeding rates appear low. Prophylactic transfusion strategies based on arbitrary thresholds lack evidence of clinical benefit. There is a pressing need for point-of-care coagulation tests that represent the complex coagulopathy of cirrhosis and well-powered randomised controlled trials to develop evidence-based pre-procedure transfusion guidelines.

Effects of Enzymatically Depolymerized Low Molecular Weight Heparins on CCl4-Induced Liver Fibrosis

With regard to identifying the effective components of LMWH drugs curing hepatic fibrosis disease, we carried out a comparative study on the efficacy of enzymatically depolymerized LMWHs on CCl₄ induced mouse liver fibrosis. The results showed that the controlled enzymatic depolymerization conditions resulted in LMWHs with significantly different activities. The LMWH product depolymerized by Heparinase I (I-11) with a Mw of 7160, exhibited a significant advantage in reducing the liver inflammation by suppressing TNF-α and IL-1β secretion, and minimizing hepatic fibrogenesis. The products prepared by only Heparinase II (II-11), and combined Heparinase III and II (III-II-5) showed limited positive effect on hepatic inflammation and fibrosis. On the contrary, the products by combined Heparinase III and I (III-I-9, III-I-5) showed no effect or stimulation effect on the hepatic fibrogenesis. Our results provided the basis for structure-activity relationship insight for inhibition of liver fibrosis activities of LMWHs, which might have significant implications for generic anti-fibrosis disease drug development.

Hepatic Osteodystrophy: The Mechanism of Bone Loss in Hepatocellular Disease and the Effects of Pamidronate Treatment

OBJECTIVES:

The present study was designed to evaluate the bone phenotypes and mechanisms involved in bone disorders associated with hepatic osteodystrophy. Hepatocellular disease was induced by carbon tetrachloride (CCl4). In addition, the effects of disodium pamidronate on bone tissue were evaluated.

METHODS:

The study included 4 groups of 15 mice: a) C = mice subjected to vehicle injections; b) C+P = mice subjected to vehicle and pamidronate injections; c) CCl4+V = mice subjected to CCl4 and vehicle injections; and d) CCl4+P = mice subjected to CCl4 and pamidronate injections. CCl4 or vehicle was administered for 8 weeks, while pamidronate or vehicle was injected at the end of the fourth week. Bone histomorphometry and biomechanical analysis were performed in tibiae, while femora were used for micro-computed tomography and gene expression.

RESULTS:

CCl4 mice exhibited decreased bone volume/trabecular volume and trabecular numbers, as well as increased trabecular separation, as determined by bone histomorphometry and micro-computed tomography, but these changes were not detected in the group treated with pamidronate. CCl4 mice showed increased numbers of osteoclasts and resorption surface. High serum levels of receptor activator of nuclear factor-κB ligand and the increased expression of tartrate-resistant acid phosphatase in the bones of CCl4 mice supported the enhancement of bone resorption in these mice.

CONCLUSION:

Taken together, these results suggest that bone resorption is the main mechanism of bone loss in chronic hepatocellular disease in mice.

Anticoagulant therapy with fondaparinux in a liver transplant patient with thrombosis and liver fibrosis: a case report

The treatment with fondaparinux is the effective and safe anticoagulant therapy in liver transplant patient on immunosuppressive therapy with arterial thrombosis, and it seems able to reduce liver fibrosis. Although this treatment is not generalizable, further prospective large studies need to confirm this case report.

Non-anticoagulant effects of low molecular weight heparins in inflammatory disorders: A review

Low molecular weight heparins (LMWHs) are produced by chemical or enzymatic depolymerization of unfractionated heparin (UFH). Besides their well-known anticoagulant effects, LMWHs have also been reported to exhibit numerous anti-inflammatory properties. Previous studies have, however, shown that different production processes result in unique structural characteristics of LMWHs. The structural variations may help explain the different therapeutic spectrums in disease treatment for non-anticoagulant effects. In the present review, we summarize major advances in understanding and exploiting the anti-inflammatory disorder activities of LMWHs, based on mechanistic studies, preclinical experiments and clinical trials. We highlight differences in these activities of commercially available LMWHs produced using different manufacturing processes. We stress the importance of structure-activity relationship (SAR) studies on the non-anticoagulant effects of LMWHs and discuss strategies for exploring new clinical indications.

Assessment of haemostasis in patients with cirrhosis: Relevance of the ROTEM tests?: A prospective, cross-sectional study

BACKGROUND

In patients with cirrhosis, decreased rotational thromboelastometry (ROTEM) parameters suggest hypocoagulability secondary to liver dysfunction. However, observed normal or increased thrombin generation suggests preserved haemostasis and/or a procoagulant state. The correlated levels of both coagulation factors and inhibitors also support preserved haemostasis.

OBJECTIVE

The objective of this study is to investigate the correlation between three specific approaches of haemostasis (ROTEM, thrombin generation and coagulation factors/inhibitors) on the same plasma sample from patients with cirrhosis.

DESIGN

A prospective, observational study.

SETTING

Single university hospital.

PARTICIPANTS

Forty patients with cirrhosis.

INTERVENTION

Measurement of the following factors: model for end-stage liver disease (MELD) scores; ROTEM maximum clot firmness (ROTEM-MCF) in EXTEM, INTEM, FIBTEM assays; fibrinogen; factors V and VIII; von Willebrand factor; protein C; protein S; antithrombin; and the thrombin generation test (TGT) enabling the calculation of endogenous thrombin potential without and with thrombomodulin, and the ratio of endogenous thrombin potential with-to-without thrombomodulin (regarded as an index of hypercoagulability).

RESULTS

ROTEM-MCF values were distributed within the normal and hypocoagulation ranges; were correlated to variations in factor V, fibrinogen, protein C and S and antithrombin; and were inversely correlated to MELD scores (ρ > 0.5; P < 0.05). Levels of von Willebrand factor were above normal and were not correlated with any other factor levels. After addition of thrombomodulin, endogenous thrombin potential values were distributed within or above normal values. Factor V variation was correlated to the ratio of endogenous thrombin potential with-to-without thrombomodulin.

CONCLUSION

ROTEM indicated hypocoagulability correlated to liver dysfunction. In contrast, the TGT indicated a preserved or even increased coagulation profile (which was supported by the correlation between coagulant factors and inhibitors) and a potential for hypercoagulability inversely correlated to the degree of liver dysfunction. ROTEM may not be appropriate for haemostasis assessment in patients with liver cirrhosis and could lead to the unnecessary transfusion of fresh frozen plasma.

TRIAL REGISTRATION

S.C. 3024 - ID RCB: 2012-A01728-35.

Role of hemostatic factors in hepatic injury and disease: animal models de-liver

Chronic liver damage is associated with unique changes in the hemostatic system. Patients with liver disease often show a precariously rebalanced hemostatic system, which is easily tipped towards bleeding or thrombotic complications by otherwise benign stimuli. In addition, some clinical studies have shown that hemostatic system components contribute to the progression of liver disease. There is a strong basic science foundation for clinical studies with this particular focus. Chronic and acute liver disease can be modeled in rodents and large animals with a variety of approaches, which span chronic exposure to toxic xenobiotics, diet-induced obesity, and surgical intervention. These experimental approaches have now provided strong evidence that, in addition to perturbations in hemostasis caused by liver disease, elements of the hemostatic system have powerful effects on the progression of experimental liver toxicity and disease. In this review, we cover the basis of the animal models that are most often utilized to assess the impact of the hemostatic system on liver disease, and highlight the role that coagulation proteases and their targets play in experimental liver toxicity and disease, emphasizing key similarities and differences between models. The need to characterize hemostatic changes in existing animal models and to develop novel animal models recapitulating the coagulopathy of chronic liver disease is highlighted. Finally, we emphasize the continued need to translate knowledge derived from highly applicable animal models to improve our understanding of the reciprocal interaction between liver disease and the hemostatic system in patients.

Hepatic sinusoids in liver injury, inflammation, and fibrosis: new pathophysiological insights

Changes of hepatic sinusoids are crucial in the pathogenesis of liver cirrhosis and portal hypertension. Liver injury leads to distinct morphological abnormalities such as loss of sinusoidal fenestration, vasoconstriction, and angiogenesis as well as molecular changes. Communication between the two key cells in this hepatic microenvironment-hepatic stellate cells (HSC) and sinusoidal endothelial cells (SEC)-has been studied for many years and several canonical pathways have been elucidated, such as decreased eNOS activity or increased PDGF and TGF-β production leading to activation and migration of HSC. In recent studies, alternative pathways of intercellular communication in liver diseases have been described such as cell-derived extracellular vesicles called exosomes, which deliver cell compounds to their target cells. Moreover, such extracellular vesicles may link injury to inflammation in alcoholic hepatitis. While inflammation leading to liver fibrosis has been studied in detail, in some circumstances pathways other than the known canonical inflammatory pathways may contribute to hepatic fibrogenesis. For example, in congestive hepatopathy, sinusoidal dilatation and fibrosis have been shown to be mediated by non-inflammatory mechanisms and associated with sinusoidal thrombi. A recently developed murine model further enables experimental studies of this disease entity. Increasing knowledge about these alternative disease pathways in liver injury, inflammation, and fibrosis may reveal possible target molecules for future therapies. This article builds upon a seminar given at the recent 3rd JSGE International Topic Conference in Sendai, Japan, and reviews the areas outlined above.

Direct Oral Anticoagulants in Cirrhosis Patients Pose Similar Risks of Bleeding When Compared to Traditional Anticoagulation

BACKGROUND AND AIMS

Direct oral anticoagulants (DOAC) are important new anticoagulant therapies that are not well studied in patients with chronic liver disease. The aim of this study was to compare rates of bleeding in cirrhosis patients treated with DOAC (factor Xa inhibitors: rivaroxaban and apixaban) to those in cirrhosis patients treated with traditional anticoagulation (warfarin and low molecular weight heparin).

METHODS

We identified a total of 39 patients with cirrhosis who received anticoagulation therapy over a 3-year period (20 DOAC and 19 traditional anticoagulation) from a research database. Medical records were reviewed to obtain clinical data to compare between the groups.

RESULTS

Clinical characteristics between the two groups were similar. There were three documented bleeding events in the traditional anticoagulation group and four bleeding events in the DOAC group (p = 0.9). There were two major bleeding events in the traditional anticoagulation group and one major bleeding event in the DOAC group. There were no documented reports of drug-induced liver injury during this study period. Among all patients, no significant predictors of bleeding were identified using univariate regression and Cox proportional hazard modeling.

CONCLUSIONS

This is the first clinical study evaluating the use of DOAC in patients with cirrhosis. DOAC display similar safety characteristics when compared to traditional anticoagulation in patients with cirrhosis and are potentially attractive agents for anticoagulation therapy. Larger studies are now needed to better understand the safety and efficacy of these agents in cirrhosis.

Role of Fibrin(ogen) in Progression of Liver Disease: Guilt by Association?

Strong experimental evidence indicates that components of the hemostatic system, including thrombin, exacerbate diverse features of experimental liver disease. Clinical studies have also begun to address this connection and some studies have suggested that anticoagulants can improve outcome in patients with liver disease. Among the evidence of coagulation cascade activation in models of liver injury and disease is the frequent observation of thrombin-driven hepatic fibrin(ogen) deposition. Indeed, hepatic fibrin(ogen) deposition has long been recognized as a consequence of hepatic injury. Although commonly inferred as pathologic due to protective effects of anticoagulants in mouse models, the role of fibrin(ogen) in acute liver injury and chronic liver disease may not be universally detrimental. The localization of hepatic fibrin(ogen) deposits within the liver is connected to the disease stimulus and in animal models of liver toxicity and chronic disease, fibrin(ogen) deposition may not always be synonymous with large vessel thrombosis. Here, we provide a balanced review of the experimental evidence supporting a direct connection between fibrin(ogen) and liver injury/disease pathogenesis, and suggest a path forward bridging experimental and clinical research to improve our knowledge on the nature and function of fibrin(ogen) in liver disease.

Direct Oral Anticoagulants in Cirrhosis

OPINION STATEMENT

The risk of thrombosis in patients with chronic liver disease is increasingly recognized. As patients with cirrhosis develop indications for anticoagulation therapy (e.g., venous thromboembolism, portal vein thrombosis, or atrial fibrillation), providers are left to make difficult decisions when selecting therapeutics with little evidence to rely on. Current practice supports the use of low molecular weight heparin or vitamin K antagonists in select patients with cirrhosis requiring anticoagulation. While traditional anticoagulants may be safe and effective in select patients with compensated cirrhosis, the use of direct oral anticoagulants (DOAC) is more controversial. DOAC are desirable as they do not require routine monitoring and can be taken orally. Unfortunately, patients with chronic liver disease were excluded from clinical trials that demonstrated efficacy and safety when compared to traditional anticoagulation. Data are now emerging that support the use of DOAC in well-compensated cirrhosis patients. However, further study is needed with all (traditional and DOAC) anticoagulation medications in patients with cirrhosis to better ensure safety and further understand pharmacologic properties in this challenging population.

Enoxaparin reduces hepatic vascular resistance and portal pressure in cirrhotic rats

BACKGROUND & AIMS

Increased hepatic vascular resistance due to fibrosis and elevated hepatic vascular tone is the primary factor in the development of portal hypertension. Heparin may decrease fibrosis by inhibiting intrahepatic microthrombosis and thrombin-mediated hepatic stellate cell activation. In addition, heparin enhances eNOS activity, which may reduce hepatic vascular tone. Our study aimed at evaluating the effects of acute, short-, long-term and preventive enoxaparin administration on hepatic and systemic hemodynamics, liver fibrosis and nitric oxide availability in cirrhotic rats.

METHODS

Enoxaparin (1.8 mg/kg subcutaneously), or its vehicle, was administered to CCl4-cirrhotic rats 24h and 1h before the study (acute), daily for 1 week (short-term) or daily for 3 weeks (long-term) and to thioacetamide-cirrhotic rats daily for 3 weeks with/without thioacetamide (preventive/long-term, respectively). Mean arterial pressure, portal pressure, portal blood flow, hepatic vascular resistance and molecular/cellular mechanisms were evaluated.

RESULTS

No significant changes in hemodynamic parameters were observed in acute administration. However, one-week, three-week and preventive treatments significantly decreased portal pressure mainly due to a decrease in hepatic vascular resistance without significant changes in mean arterial pressure. These findings were associated with significant reductions in liver fibrosis, hepatic stellate cell activation, and desmin expression. Moreover, a reduction in fibrin deposition was observed in enoxaparin-treated rats, suggesting reduced intrahepatic microthrombosis.

CONCLUSION

Enoxaparin reduces portal pressure in cirrhotic rats by improving the structural component of increased liver resistance. These findings describe the potentially beneficial effects of enoxaparin beyond the treatment/prevention of portal vein thrombosis in cirrhosis, which deserve further investigation.

Efficacy and safety of anticoagulation in more advanced portal vein thrombosis in patients with liver cirrhosis

BACKGROUND AND AIM

Portal vein thrombosis (PVT) is a frequent event in patients with cirrhosis. The effects of anticoagulation on these patients were still unclear, especially for more advanced PVT. The aim of this study was to retrospectively assess the resolution of PVT and liver disease progression in a large cohort of cirrhotic patients with PVT with or without anticoagulation therapy.

METHODS

We analyzed data from 66 cirrhotic patients with PVT from January 2002 to June 2014. Thirty patients were anticoagulated with warfarin and 36 patients were untreated. PVT and hepatic decompensation were evaluated.

RESULTS

For anticoagulated patients, the thrombosis had improved in 15 (68.2%) patients, was stable in four patients (18.2%), and progressed in three patients (13.6%). For untreated patients, the thrombosis had improved in four patients (25%), was stable in six patients (37.5%), and progressed in six patients (37.5%). The anticoagulation group had significantly better recanalization rates than the untreated group (P=0.011). Degree of superior mesenteric vein (P=0.032, hazard ratio: 15.4; 95% confidence interval: 1.3-200) was a significant predictor. In addition, anticoagulation can effectively improve PVT with a degree less than 75% in the main portal vein compared with untreated patients (6/6 vs. 2/6, P=0.030). The probability of hepatic decompensation at 1 year was 15.6 and 17.9% between the anticoagulation and the untreated groups (P=0.847). Albumin (P=0.06, hazard ratio: 0.860; 95% confidence interval: 0.772-0.959) was a significant predictor.

CONCLUSION

Anticoagulation with warfarin might result in the resolution of more advanced PVT effectively and safely in patients with liver cirrhosis. In addition, we did not demonstrate the benefit of anticoagulation for the decompensation or death.

Chemical exchange saturation transfer (CEST) MR technique for in-vivo liver imaging at 3.0 tesla

PURPOSE

To evaluate Chemical Exchange Saturation Transfer (CEST) MRI for liver imaging at 3.0-T.

MATERIALS AND METHODS

Images were acquired at offsets (n = 41, increment = 0.25 ppm) from -5 to 5 ppm using a TSE sequence with a continuous rectangular saturation pulse. Amide proton transfer-weighted (APTw) and GlycoCEST signals were quantified as the asymmetric magnetization transfer ratio (MTRasym) at 3.5 ppm and the total MTRasym integrated from 0.5 to 1.5 ppm, respectively, from the corrected Z-spectrum. Reproducibility was assessed for rats and humans. Eight rats were devoid of chow for 24 hours and scanned before and after fasting. Eleven rats were scanned before and after one-time CCl4 intoxication.

RESULTS

For reproducibility, rat liver APTw and GlycoCEST measurements had 95 % limits of agreement of -1.49 % to 1.28 % and -0.317 % to 0.345 %. Human liver APTw and GlycoCEST measurements had 95 % limits of agreement of -0.842 % to 0.899 % and -0.344 % to 0.164 %. After 24 hours, fasting rat liver APTw and GlycoCEST signals decreased from 2.38 ± 0.86 % to 0.67 ± 1.12 % and from 0.34 ± 0.26 % to -0.18 ± 0.37 % respectively (p < 0.05). After CCl4 intoxication rat liver APTw and GlycoCEST signals decreased from 2.46 ± 0.48 % to 1.10 ± 0.77 %, and from 0.34 ± 0.23 % to -0.16 ± 0.51 % respectively (p < 0.05).

CONCLUSION

CEST liver imaging at 3.0-T showed high sensitivity for fasting as well as CCl4 intoxication.

KEY POINTS

• CEST MRI of in-vivo liver was demonstrated at clinical 3 T field strength. • After 24-hour fasting, rat liver APTw and GlycoCEST signals decreased significantly. • After CCl4 intoxication both rat liver APTw and GlycoCEST signals decreased significantly. • Good scan-rescan reproducibility of liver CEST MRI was shown in healthy volunteers.

Identification of core active disaccharides in heparin for HGF-inducing activity

Objectives:

To ascertain the positions of sulfated groups for HGF-inducing activity using differently sulfated heparin disaccharides and to investigate whether the heparin disaccharide elevates HGF levels in plasma in vivo and exerts protective effects on acute liver injury.

Materials and Methods:

The heparin disaccharides ΔUA-GlcNS, ΔUA (2S)-GlcN, ΔUA-GlcNAc (6S), ΔUA-GlcNS (6S), ΔUA (2S)-GlcNS, ΔUA (2S)-GlcNAc (6S), ΔUA-GlcNAc and ΔUA (2S)-GlcNS (6S) were added to MRC-9 fibroblasts and HGF concentrations in culture media were determined by enzyme-linked immunosorbent assay. Furthermore, ΔUA-GlcNS (100 μg/head) was injected into C57BL/6 mice and plasma levels of HGF measured at 12 h. After acute hepatitis was induced by CCl₄ (15 mg/kg) in mice, liver specimens were stained with hematoxylin and eosin (H and E). Levels of aspartate aminotransferase and alanine aminotransferase were measured at 24 h.

Results:

Among the disaccharides investigated, ΔUA-GlcNS, ΔUA-GlcNAc (6S) and ΔUA-GlcNS (6S) stimulated HGF production in MRC-9 fibroblasts. However, none of the 2-O-sulfated disaccharides [ΔUA (2S)-GlcNS, ΔUA (2S)-GlcNAc (6S) and ΔUA (2S)-GlcNS (6S)] showed any activity despite the presence of N-sulfated and/or 6-O-sulfated disaccharides. Thus, 2-O-sulfation of hexuronic acid has an inhibitory effect. Moreover, ΔUA-GlcNS administration increased plasma levels of HGF in normal mice and prevented CCl₄-induced liver injury in mice.

Conclusions:

N-sulfation and/or 6-O-sulfation of glucosamine with nonsulfated hexuronic acid provides a structural basis for the HGF-inducing activity of disaccharides. ΔUA-GlcNS increases plasma levels of HGF and protects against CCl₄-induced acute liver injury.

Chronic passive venous congestion drives hepatic fibrogenesis via sinusoidal thrombosis and mechanical forces

Chronic passive hepatic congestion (congestive hepatopathy) leads to hepatic fibrosis; however, the mechanisms involved in this process are not well understood. We developed a murine experimental model of congestive hepatopathy through partial ligation of the inferior vena cava (pIVCL). C57BL/6 and transgenic mice overexpressing tissue factor pathway inhibitor (SM22α-TFPI) were subjected to pIVCL or sham. Liver and blood samples were collected and analyzed in immunohistochemical, morphometric, real-time polymerase chain reaction, and western blot assays. Hepatic fibrosis and portal pressure were significantly increased after pIVCL concurrent with hepatic stellate cell (HSC) activation. Liver stiffness, as assessed by magnetic resonance elastography, correlated with portal pressure and preceded fibrosis in our model. Hepatic sinusoidal thrombosis as evidenced by fibrin deposition was demonstrated both in mice after pIVCL as well as in humans with congestive hepatopathy. Warfarin treatment and TFPI overexpression both had a protective effect on fibrosis development and HSC activation after pIVCL. In vitro studies show that congestion stimulates HSC fibronectin (FN) fibril assembly through direct effects of thrombi as well as by virtue of mechanical strain. Pretreatment with either Mab13 or Cytochalasin-D, to inhibit β-integrin or actin polymerization, respectively, significantly reduced fibrin and stretch-induced FN fibril assembly.

CONCLUSION

Chronic hepatic congestion leads to sinusoidal thrombosis and strain, which in turn promote hepatic fibrosis. These studies mechanistically link congestive hepatopathy to hepatic fibrosis.