Hypoxia, angiogenesis and liver fibrogenesis in the progression of chronic liver diseases

Fibrosis and Hepatocarcinogenesis: Role of Gene-Environment Interactions in Liver Disease Progression

The liver is a complex organ that performs vital functions in the body. Despite its extraordinary regenerative capacity compared to other organs, exposure to chemical, infectious, metabolic and immunologic insults and toxins renders the liver vulnerable to inflammation, degeneration and fibrosis. Abnormal wound healing response mediated by aberrant signaling pathways causes chronic activation of hepatic stellate cells (HSCs) and excessive accumulation of extracellular matrix (ECM), leading to hepatic fibrosis and cirrhosis. Fibrosis plays a key role in liver carcinogenesis. Once thought to be irreversible, recent clinical studies show that hepatic fibrosis can be reversed, even in the advanced stage. Experimental evidence shows that removal of the insult or injury can inactivate HSCs and reduce the inflammatory response, eventually leading to activation of fibrolysis and degradation of ECM. Thus, it is critical to understand the role of gene-environment interactions in the context of liver fibrosis progression and regression in order to identify specific therapeutic targets for optimized treatment to induce fibrosis regression, prevent HCC development and, ultimately, improve the clinical outcome.

Portosystemic shunt placement reveals blood signatures for the development of hepatic encephalopathy through mass spectrometry

Elective transjugular intrahepatic portosystemic shunt (TIPS) placement can worsen cognitive dysfunction in hepatic encephalopathy (HE) patients due to toxins, including possible microbial metabolites, entering the systemic circulation. We conducted untargeted metabolomics on a prospective cohort of 22 patients with cirrhosis undergoing elective TIPS placement and followed them up to one year post TIPS for HE development. Here we suggest that pre-existing intrahepatic shunting predicts HE severity post-TIPS. Bile acid levels decrease in the peripheral vein post-TIPS, and the abundances of three specific conjugated di- and tri-hydroxylated bile acids are inversely correlated with HE grade. Bilirubins and glycerophosphocholines undergo chemical modifications pre- to post-TIPS and based on HE grade. Our results suggest that TIPS-induced metabolome changes can impact HE development, and that pre-existing intrahepatic shunting could be used to predict HE severity post-TIPS.

Effects of hypoxia and reoxygenation on oxidative stress, histological structure, and apoptosis in a new hypoxia-tolerant variety of blunt snout bream (Megalobrama amblycephala)

A new hypoxia-tolerant variety of blunt snout bream was obtained by successive breeding of the wild population, which markedly improved hypoxia tolerance. In this study, the hypoxia-tolerant variety was exposed to hypoxia (2.0 mg O₂·L^-1) for 4, 7 days. The contents of blood biochemical indicators including the number of red blood cells (RBC), total cholesterol (T-CHO), total protein (TP), triglyceride (TG), glucose (GLU), and lactic acid (LD) increased significantly (P < 0.05) under hypoxia. The glycogen content in the liver and muscle decreased significantly (P < 0.05) and the LD content in the brain, muscle and liver increased significantly (P < 0.05) under hypoxia. The levels of oxidative stress-related indicators i.e., superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), catalase (CAT), and total antioxidant capacity (T-AOC) also changed significantly (P < 0.05) in the heart, liver, and intestine of the new variety under hypoxia. Additionally, hypoxia has caused injuries to the heart, liver, and intestine, but it shows amazing repair ability during reoxygenation. The apoptotic cells and apoptosis rate in the heart, liver, and intestine increased under hypoxia. Under hypoxia, the expression of the B-cell lymphomas 2 (Bcl-2) gene in the heart, liver, and intestine was significantly (P < 0.05) down-regulated, while the expression of the BCL2-associated agonist of cell death (Bad) gene was significantly (P < 0.05) up-regulated. These results are of great significance for enriching the basic data of blunt snout bream new variety in response to hypoxia and promoting the healthy development of its culture industry.

Genome-wide liver transcriptomic profiling of a malaria mouse model reveals disturbed immune and metabolic responses

BACKGROUND

The liver is responsible for a range of functions in vertebrates, such as metabolism and immunity. In malaria, the liver plays a crucial role in the interaction between the parasite and host. Although malarial hepatitis is a common clinical complication of severe malaria, other malaria-related liver changes have been overlooked during the blood stage of the parasite life-cycle, in contrast to the many studies that have focused on parasite invasion of and replication in the liver during the hepatic stage of the parasite.

METHODS

A rodent model of malaria was established using Plasmodium yoelii strain 17XL, a lethal strain of rodent malaria, for liver transcriptomic profiling.

RESULTS

Differentially expressed messenger RNAs were associated with innate and adaptive immune responses, while differentially expressed long noncoding RNAs were enriched in the regulation of metabolism-related pathways, such as lipid metabolism. The coexpression network showed that host genes were related to cellular transport and tissue remodeling. Hub gene analysis of P. yoelii indicated that ubiquitination genes that were coexpressed with the host were evolutionarily conserved.

CONCLUSIONS

Our analysis yielded evidence of activated immune responses, aberrant metabolic processes and tissue remodeling changes in the livers of mice with malaria during the blood stage of the parasite, which provided a systematic outline of liver responses during Plasmodium infection.

Pre- and Post-Portosystemic Shunt Placement Metabolomics Reveal Molecular Signatures for the Development of Hepatic Encephalopathy

Hepatic encephalopathy (HE) is a common complication of advanced liver disease causing brain dysfunction. This is likely due to the accumulation of unfiltered toxins within the bloodstream. A known risk factor for developing or worsening HE is the placement of a transjugular intrahepatic portosystemic shunt (TIPS), which connects the pre-hepatic and post-hepatic circulation allowing some blood to bypass the dysfunctional liver and decreases portal hypertension. To better understand the pathophysiology of post-TIPS HE, we conducted a multi-center prospective cohort study employing metabolomic analyses on hepatic vein and peripheral vein blood samples from participants with cirrhosis undergoing elective TIPS placement, measuring chemical modifications and changes in concentrations of metabolites resulting from TIPS placement. In doing so, we identified numerous alterations in metabolites, including bile acids, glycerophosphocholines, and bilirubins possibly implicated in the development and severity of HE.

Anlotinib improves bile duct ligature‐induced liver fibrosis in rats via antiangiogenesis regulated by VEGFR2/mTOR pathway

Cholestasis is a main clinical feature of biliary atresia (BA), which leads to liver fibrosis (LF). The focus of BA treatment is preventing and slowing the progress of LF. This study reports the improvement effect of anlotinib on common bile duct ligature (BDL)-induced LF in young rats. The BDL young rats were treated with anlotinib and the serum levels of aspartate aminotransferase, alanine aminotransferase, albumin, and total bilirubin were determined. Histological staining was performed and pathological changes in liver tissue were observed. The expression levels of α-SMA, collagen I, CD31, TGF-β1, phospho-VEGFR2, phospho-4E/BP1, and phospho-S6K1 were determined. The results showed that anlotinib significantly improved the liver function and histopathological injury of BDL rats, inhibited the deposition of collagen and hepatocyte apoptosis, and downregulated the protein expression of α-SMA and collagen I. Furthermore, anlotinib treatment significantly inhibited microvascular formation in the liver and downregulated the expression level of phospho-VEGFR2, thereby suggesting that the antifibrosis effect of anlotinib may be achieved by antiangiogenesis. In addition, anlotinib downregulated the expression of phospho-S6K1 and upregulated the expression of phospho-4E/BP1, two downstream proteins of the mammalian target of rapamycin (mTOR) pathway. MHY1485, an agonist of mTOR, significantly reversed the inhibitory effect of anlotinib on angiogenesis and LF but did not influence the effect of anlotinib on the downregulation of phospho-VEGFR2 expression. Together, the above-mentioned results suggest that the effect of anlotinib on BDL-induced LF involves at least antiangiogenesis regulated by the VEGFR2/mTOR signaling pathway.

Therapeutic potential of targeting regulatory mechanisms of hepatic stellate cell activation in liver fibrosis

Hepatic fibrosis is a manifestation of different etiologies of liver disease with the involvement of multiple mediators in complex network interactions. Activated hepatic stellate cells (aHSCs) are the central driver of hepatic fibrosis, given their potential to induce connective tissue formation and extracellular matrix (ECM) protein accumulation. Therefore, identifying the cellular and molecular pathways involved in the activation of HSCs is crucial in gaining mechanistic and therapeutic perspectives to more effectively target the disease. In addition to a comprehensive summary of our current understanding of the role of HSCs in liver fibrosis, we also discuss here the proposed therapeutic strategies based on targeting HSCs.

Hypoxia, Hypoxia-Inducible Factors and Liver Fibrosis

Liver fibrosis is a potentially reversible pathophysiological event, leading to excess deposition of extracellular matrix (ECM) components and taking place as the net result of liver fibrogenesis, a dynamic and highly integrated process occurring during chronic liver injury of any etiology. Liver fibrogenesis and fibrosis, together with chronic inflammatory response, are primarily involved in the progression of chronic liver diseases (CLD). As is well known, a major role in fibrogenesis and fibrosis is played by activated myofibroblasts (MFs), as well as by macrophages and other hepatic cell populations involved in CLD progression. In the present review, we will focus the attention on the emerging pathogenic role of hypoxia, hypoxia-inducible factors (HIFs) and related mediators in the fibrogenic progression of CLD.

Diagnostic Accuracy of Serum Hyaluronan for Detecting HCV Infection and Liver Fibrosis in Asymptomatic Blood Donors

Background: The disease caused by hepatitis C virus (HCV) is asymptomatic, silent, and progressive liver disease. In HCV-infected patients the increase in serum HA is associated with the development of hepatic fibrosis and disease progression. Methods: HCV-RNA detection was performed in all serological samples of blood donors that tested positive using HCV Ultra ELISA. Determination of hyaluronan (HA) was performed in positive HCV samples using ELISA-like fluorometric method. The HA content was compared to HCV viral load, genotype of the virus, liver fibrosis as well as ALT and GGT liver biomarkers. Results: Persistently normal ALT (<40 U/L) and GGT (<50 U/L) serum levels were detected in 75% and 69% of the HCV-Infected blood donors, respectively. Based on ROC analysis, the HA value < 34.2 ng/mL is an optimal cut-off point to exclude HCV viremia (specificity = 91%, NPV = 99%). Applying HA value ≥34.2 ng/mL significant liver fibrosis (≥F2) can be estimated in 46% of the HCV-infected blood donors. HA serum level (≥34.2 ng/mL) associated with a high ALT level (>40 U/mL) can correctly identify HCV infection and probable liver fibrosis (sensitivity = 96% and specificity = 90%) in asymptomatic blood donors. Conclusions: A high level of HA (≥34.2 ng/mL) in association with ALT (≥40 U/L) in serum can provide a good clinical opportunity to detect HCV-infected asymptomatic persons that potentially require a liver biopsy confirmation and antiviral treatment to prevent the development of advanced liver fibrosis or cirrhosis.

Angiogenesis in the progression from liver fibrosis to cirrhosis and hepatocelluar carcinoma

Introduction: Persistent inflammation and hypoxia are strong stimulus for pathological angiogenesis and vascular remodeling, and are also the most important elements resulting in liver fibrosis. Sustained inflammatory process stimulates fibrosis to the end-point of cirrhosis and sinusoidal portal hypertension is an important feature of cirrhosis. Neovascularization plays a pivotal role in collateral circulation formation of portal vein, mesenteric congestion, and high perfusion. Imbalance of hepatic artery and portal vein blood flow leads to the increase of hepatic artery inflow, which is beneficial to the formation of nodules. Angiogenesis contributes to progression from liver fibrosis to cirrhosis and hepatocellular carcinoma (HCC) and anti-angiogenesis therapy can improve liver fibrosis, reduce portal pressure, and prolong overall survival of patients with HCC. Areas covers: This paper will try to address the difference of the morphological characteristics and mechanisms of neovascularization in the process from liver fibrosis to cirrhosis and HCC and further compare the different efficacy of anti-angiogenesis therapy in these three stages. Expert opinion: More in-depth understanding of the role of angiogenesis factors and the relationship between angiogenesis and other aspects of the pathogenesis and transformation may be the key to enabling future progress in the treatment of patients with liver fibrosis, cirrhosis, and HCC.

Lenvatinib prevents liver fibrosis by inhibiting hepatic stellate cell activation and sinusoidal capillarization in experimental liver fibrosis

Molecular targeted agents are pharmacologically used to treat liver fibrosis and have gained increased attention. The present study examined the preventive effect of lenvatinib on experimental liver fibrosis and sinusoidal capillarization as well as the in vitro phenotypes of hepatic stellate cells. LX-2, a human stellate cell line, was used for in vitro studies. In vivo liver fibrosis was induced in F344 rats using carbon tetrachloride by intraperitoneal injection for 8 weeks, and oral administration of lenvatinib was started two weeks after initial injection of carbon tetrachloride. Lenvatinib restrained proliferation and promoted apoptosis of LX-2 with suppressed phosphorylation of extracellular signal-regulated kinase 1/2 and AKT. It also down-regulated COL1A1, ACTA2 and TGFB1 expressions by inhibiting the transforming growth factor-β1/Smad2/3 pathway. Treatment with lenvatinib also suppressed platelet-derived growth factor-BB-stimulated proliferation, chemotaxis and vascular endothelial growth factor-A production, as well as basic fibroblast growth factor-induced LX-2 proliferation. In vivo study showed that lenvatinib attenuated liver fibrosis development with reduction in activated hepatic stellate cells and mRNA expression of profibrogenic markers. Intrahepatic neovascularization was ameliorated with reduced hepatic expressions of Vegf1, Vegf2 and Vegfa in lenvatinib-treated rats. Collectively, these results suggest the potential use of lenvatinib as a novel therapeutic strategy for liver fibrosis.

New insights on the role of vascular endothelial growth factor in biliary pathophysiology

The family of vascular endothelial growth factors (VEGFs) includes 5 members (VEGF-A to -D, and placenta growth factor), which regulate several critical biological processes. VEGF-A exerts a variety of biological effects through high-affinity binding to tyrosine kinase receptors (VEGFR-1, -2 and -3), co-receptors and accessory proteins. In addition to its fundamental function in angiogenesis and endothelial cell biology, VEGF/VEGFR signalling also plays a role in other cell types including epithelial cells. This review provides an overview of VEGF signalling in biliary epithelial cell biology in both normal and pathologic conditions. VEGF/VEGFR-2 signalling stimulates bile duct proliferation in an autocrine and paracrine fashion. VEGF/VEGFR-1/VEGFR-2 and angiopoietins are involved at different stages of biliary development. In certain conditions, cholangiocytes maintain the ability to secrete VEGF-A, and to express a functional VEGFR-2 receptor. For example, in polycystic liver disease, VEGF secreted by cystic cells stimulates cyst growth and vascular remodelling through a PKA/RAS/ERK/HIF1α-dependent mechanism, unveiling a new level of complexity in VEFG/VEGFR-2 regulation in epithelial cells. VEGF/VEGFR-2 signalling is also reactivated during the liver repair process. In this context, pro-angiogenic factors mediate the interactions between epithelial, mesenchymal and inflammatory cells. This process takes place during the wound healing response, however, in chronic biliary diseases, it may lead to pathological neo-angiogenesis, a condition strictly linked with fibrosis progression, the development of cirrhosis and related complications, and cholangiocarcinoma. Novel observations indicate that in cholangiocarcinoma, VEGF is a determinant of lymphangiogenesis and of the immune response to the tumour. Better insights into the role of VEGF signalling in biliary pathophysiology might help in the search for effective therapeutic strategies.

Oxidative stress, immunological and cellular hypoxia biomarkers in hepatitis C treatment-naïve and cirrhotic patients

INTRODUCTION

Hepatitis C virus (HCV) is the main cause of chronic liver disease, with calamitous complications. Its highest rate is recorded in Egypt. This study investigated whether oxidative stress, immunological chaos and cellular hypoxia are implicated in the pathophysiology of the disease.

MATERIAL AND METHODS

This cross-sectional study aimed to evaluate the changes in blood oxidative stress, cellular hypoxia/angiogenesis and cellular immunological biomarkers in hospital-diagnosed treatment-naïve HCV-infected Upper Egyptian chronic liver disease patients vs. healthy controls (n = 40). The consecutively included patients comprised 120 with normal serum enzymes (HCV-NE) and 130 with high serum enzymes (HCV-HE), along with 120 cirrhotic patients.

RESULTS

Oxidative stress biomarkers - malondialdehyde (MDA), total peroxides and oxidative stress index (OSI) - were significantly lower in controls vs. each of the patient groups. Cirrhotic patients presented the highest levels. However, total antioxidants (TAO) showed non-significant differences among the four groups. The cellular hypoxia/angiogenesis biomarkers - lactate, vascular endothelial cell growth factor (VEGF) and its soluble receptor 1 (sVEGFR1) - vs. controls were massively increased in patient groups. VEGF was lowest while sVEGFR1 was highest among cirrhotic patients. Immunological biomarkers, - granulocyte/monocyte-colony stimulating factor (GM-CSF) and total immunoglobulin G (IgG) - were massively increased in patient groups vs. controls. GM-CSF was lowest in HCV-HE and IgG was highest in cirrhotic patients. sVEGFR1 correlated with the progression towards cirrhosis.

CONCLUSIONS

Oxidative stress is implicated in the progress of HCV infection with marked induction of cellular hypoxia and dysfunctional angiogenesis, and a futile immunological reaction. sVEGFR1 level correlated with progression towards HCV-induced liver fibrosis.

microRNA-322/424 promotes liver fibrosis by regulating angiogenesis through targeting CUL2/HIF-1α pathway

AIMS

To investigate the effects and mechanism of miR-322/424 in liver fibrosis.

MAIN METHODS

miR-322/424 expression in liver cirrhosis patients, mouse and rat liver fibrosis was determined by qPCR. Mice liver fibrosis was established by CCl₄, and intervened by miR-322/424 agomir or antagomir. Liver hydroxyproline content and Sirius red staining were used to evaluate collagen deposition. CD31 expression was used to evaluate liver microvessel density. In vitro, the effects of miR-322/424 mimic or inhibitor on human hepatic sinusoidal endothelial cells (HHSECs) migration and tube formation were investigated. A dual luciferase reporter assay was performed to confirm the direct interaction between miR-322/424 and Cullin2. mRNA expression of elongin B/C, Cullin2, and RBX1 was determined by qPCR. HIF-1α protein expression was determined by Western blotting.

KEY FINDINGS

miR-322/424 level in liver cirrhosis patients, mouse liver fibrosis induced by CCl₄ and BDL, and rat liver fibrosis induced by CCl₄ and dimethylnitrosamine was increased. miR-322/424 agomir exacerbated CCl₄-induced mouse liver fibrosis, whereas the opposite effect was observed for miR-322/424 antagomir. miR-322/424 agomir significantly upregulated liver CD31 expression; opposite effects occurred with miR-322/424 antagomir. In vitro, miR-322/424 mimic significantly promoted tube formation and cell migration, and increased von Willebrand factor expression, whereas miR-322/424 inhibitor had the opposite effect. Dual-Luciferase Reporter Assay identified Cullin2 as miR-322/424 target. miR-322/424 decreased the mRNA expression of elongin B/C, Cullin2, and RBX1 and increased HIF-1α protein expression in HHSECs.

SIGNIFICANCE

miR-322/424 plays a central role in the pathogenesis of liver fibrosis by targeting Cullin2, and enhancing HIF-1α-mediated hepatic angiogenesis.

Collagen release by human hepatic stellate cells requires vitamin C and is efficiently blocked by hydroxylase inhibition

Liver fibrosis is characterized by the accumulation of extracellular matrix proteins, mainly composed of collagen. Hepatic stellate cells (HSCs) mediate liver fibrosis by secreting collagen. Vitamin C (ascorbic acid) is a cofactor of prolyl-hydroxylases that modify newly synthesized collagen on the route for secretion. Unlike most animals, humans cannot synthesize ascorbic acid and its role in liver fibrosis remains unclear. Here, we determined the effect of ascorbic acid and prolyl-hydroxylase inhibition on collagen production and secretion by human HSCs. Primary human HSCs (p-hHSCs) and the human HSCscell line LX-2 were treated with ascorbic acid, transforming growth factor-beta (TGFβ) and/or the pan-hydroxylase inhibitor dimethyloxalylglycine (DMOG). Expression of collagen-I was analyzed by RT-qPCR (COL1A1), Western blotting, and immunofluorescence microscopy. Collagen secretion was determined in the medium by Western blotting for collagen-I and by HPLC for hydroxyproline concentrations. Expression of solute carrier family 23 members 1 and 2 (SLC23A1/SLC23A2), encoding sodium-dependent vitamin C transporters 1 and 2 (SVCT1/SVCT2) was quantified in healthy and cirrhotic human tissue. In the absence of ascorbic acid, collagen-I accumulated intracellularly in p-hHSCs and LX-2 cells, which was potentiated by TGFβ. Ascorbic acid co-treatment strongly promoted collagen-I excretion and enhanced extracellular hydroxyproline concentrations, without affecting collagen-I (COL1A1) mRNA levels. DMOG inhibited collagen-I release even in the presence of ascorbic acid and suppressed COL1A1 and alpha-smooth muscle actin (αSMA/ACTA2) mRNA levels, also under hypoxic conditions. Hepatocytes express both ascorbic acid transporters, while p-hHSCs and LX-2 express the only SVCT2, which is selectively enhanced in cirrhotic livers. Human HSCs rely on ascorbic acid for the efficient secretion of collagen-I, which can be effectively blocked by hydroxylase antagonists, revealing new therapeutic targets to treat liver fibrosis.

Photoacoustic Imaging for Assessing Tissue Oxygenation Changes in Rat Hepatic Fibrosis

Chronic liver inflammation progressively evokes fibrosis and cirrhosis resulting in compromised liver function, and often leading to cancer. Early diagnosis and staging of fibrosis is crucial because the five-year survival rate of early-stage liver cancer is high. This study investigates the progression of hepatic fibrosis induced in rats following ingestion of diethylnitrosamine (DEN). Changes in oxygen saturation and hemoglobin concentration resulting from chronic inflammation were assayed longitudinally during DEN ingestion by photoacoustic imaging (PAI). Accompanying liver tissue changes were monitored simultaneously by B-mode sonographic imaging. Oxygen saturation and hemoglobin levels in the liver increased over 5 weeks and peaked at 10 weeks before decreasing at 13 weeks of DEN ingestion. The oxygenation changes were accompanied by an increase in hepatic echogenicity and coarseness in the ultrasound image. Histology at 13 weeks confirmed the development of severe fibrosis and cirrhosis. The observed increase in PA signal representing enhanced blood oxygenation is likely an inflammatory physiological response to the dietary DEN insult that increases blood flow by the development of neovasculature to supply oxygen to a fibrotic liver during the progression of hepatic fibrosis. Assessment of oxygenation by PAI may play an important role in the future assessment of hepatic fibrosis.

The Role of Sinusoidal Endothelial Cells in the Axis of Inflammation and Cancer Within the Liver

Liver sinusoidal endothelial cells (LSEC) form a unique barrier between the liver sinusoids and the underlying parenchyma, and thus play a crucial role in maintaining metabolic and immune homeostasis, as well as actively contributing to disease pathophysiology. Whilst their endocytic and scavenging function is integral for nutrient exchange and clearance of waste products, their capillarisation and dysfunction precedes fibrogenesis. Furthermore, their ability to promote immune tolerance and recruit distinct immunosuppressive leukocyte subsets can allow persistence of chronic viral infections and facilitate tumour development. In this review, we present the immunological and barrier functions of LSEC, along with their role in orchestrating fibrotic processes which precede tumourigenesis. We also summarise the role of LSEC in modulating the tumour microenvironment, and promoting development of a pre-metastatic niche, which can drive formation of secondary liver tumours. Finally, we summarise closely inter-linked disease pathways which collectively perpetuate pathogenesis, highlighting LSEC as novel targets for therapeutic intervention.

Liver fibrogenesis: un update on established and emerging basic concepts

Liver fibrogenesis is defined as a dynamic and highly integrated process occurring during chronic injury to liver parenchyma that can result in excess deposition of extracellular matrix (ECM) components (i.e., liver fibrosis). Liver fibrogenesis, together with chronic inflammatory response, is then primarily involved in the progression of chronic liver diseases (CLD) irrespective of the specific etiology. In the present review we will first offer a synthetic and updated overview of major basic concepts in relation to the role of myofibroblasts (MFs), macrophages and other hepatic cell populations involved in CLD to then offer an overview of established and emerging issues and mechanisms that have been proposed to favor and/or promote CLD progression. A special focus will be dedicated to selected issues that include emerging features in the field of cholangiopathies, the emerging role of genetic and epigenetic factors as well as of hypoxia, hypoxia-inducible factors (HIFs) and related mediators.

The interaction between current smoking and hemoglobin on the risk of advanced fibrosis in patients with biopsy-proven nonalcoholic fatty liver disease

BACKGROUND

Higher hemoglobin levels have been associated with an increased risk for nonalcoholic fatty liver disease. Although the mechanism underlying this association is elusive, smoking has been previously related to both higher hemoglobin concentrations and an increased risk of fibrosis in nonalcoholic fatty liver disease. The present study was conducted to investigate formally the interaction among current smoking, hemoglobin levels, and risk for advanced fibrosis in patients with biopsy-proven nonalcoholic fatty liver disease.

PATIENTS AND METHODS

We examined 433 Turkish patients with biopsy-proven nonalcoholic fatty liver disease. Advanced fibrosis (F ≥ 3) was identified on liver biopsy in 80 cases, whereas 84 patients were current smokers. Logistic regression models were used to evaluate the effect of current smoking on risk for advanced fibrosis, after adjusting for the effects of age, sex, BMI, diabetes, and metabolic syndrome.

RESULTS

Preliminary analyses revealed the presence of substantial statistical interaction between current smoking and hemoglobin levels (P < 0.001). In separate multivariable analyses conducted in the entire cohort and in the subgroups of patients with high and low hemoglobin levels (according to median value in the study cohort: 14.4 g/l), current smoking was associated with increased risk for advanced fibrosis in patients with high hemoglobin (odds ratio: 3.32, 95% confidence interval: 1.23-7.21, P < 0.01) but neither in those with low hemoglobin (odds ratio: 0.71, 95% confidence interval: 0.28-1.81, P = 0.52) nor in the entire study cohort (odds ratio: 1.18, 95% confidence interval: 0.73-2.14, P = 0.79).

CONCLUSION

Hemoglobin acts as a modifier in the association between current smoking and advanced fibrosis in nonalcoholic fatty liver disease.

Hepatocellular Carcinoma Mechanisms Associated with Chronic HCV Infection and the Impact of Direct-Acting Antiviral Treatment

Hepatitis C virus (HCV) infection is the major risk factor for liver cirrhosis and hepatocellular carcinoma (HCC). The mechanisms of HCC initiation, growth, and metastasis appear to be highly complex due to the decade-long interactions between the virus, immune system, and overlapping bystander effects of host metabolic liver disease. The lack of a readily accessible animal model system for HCV is a significant obstacle to understand the mechanisms of viral carcinogenesis. Traditionally, the primary prevention strategy of HCC has been to eliminate infection by antiviral therapy. The success of virus elimination by antiviral treatment is determined by the SVR when the HCV is no longer detectable in serum. Interferon-alpha (IFN-α) and its analogs, pegylated IFN-α (PEG-IFN-α) alone with ribavirin (RBV), have been the primary antiviral treatment of HCV for many years with a low cure rate. The cloning and sequencing of HCV have allowed the development of cell culture models, which accelerated antiviral drug discovery. It resulted in the selection of highly effective direct-acting antiviral (DAA)-based combination therapy that now offers incredible success in curing HCV infection in more than 95% of all patients, including those with cirrhosis. However, several emerging recent publications claim that patients who have liver cirrhosis at the time of DAAs treatment face the risk of HCC occurrence and recurrence after viral cure. This remains a substantial challenge while addressing the long-term benefit of antiviral medicine. The host-related mechanisms that drive the risk of HCC in the absence of the virus are unknown. This review describes the multifaceted mechanisms that create a tumorigenic environment during chronic HCV infection. In addition to the potential oncogenic programming that drives HCC after viral clearance by DAAs, the current status of a biomarker development for early prediction of cirrhosis regression and HCC detection post viral treatment is discussed. Since DAAs treatment does not provide full protection against reinfection or viral transmission to other individuals, the recent studies for a vaccine development are also reviewed.

Neovascularization is a key feature of liver fibrosis progression: anti-angiogenesis as an innovative way of liver fibrosis treatment

Liver fibrosis affects over 100 million people in the world; it represents a multifactorial, fibro-inflammatory disorder characterized by exacerbated production of extracellular matrix with consequent aberration of hepatic tissue. The aetiology of this disease is very complex and seems to involve a broad spectrum of factors including the lifestyle, environment factors, genes and epigenetic changes. More evidences indicate that angiogenesis, a process consisting in the formation of new blood vessels from pre-existing vessels, plays a crucial role in the progression of liver fibrosis. Central to the pathogenesis of liver fibrosis is the hepatic stellate cells (HSCs) which represent a crossroad among inflammation, fibrosis and angiogenesis. Quiescent HSCs can be stimulated by a host of growth factors, pro-inflammatory mediators produced by damaged resident liver cell types, as well as by hypoxia, contributing to neoangiogenesis, which in turn can be a bridge between acute and chronic inflammation. As matter of fact, studies demonstrated that neutralization of vascular endothelial growth factor as well as other proangiogenic agents can attenuate the progression of liver fibrosis. With this review, our intent is to discuss the cause and the role of angiogenesis in liver fibrosis focusing on the current knowledge about the impact of anti-angiogenetic therapies in this pathology.

Rewiring Host Signaling: Hepatitis C Virus in Liver Pathogenesis

Hepatitis C virus (HCV) is a major cause of liver disease including metabolic disease, fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). HCV induces and promotes liver disease progression by perturbing a range of survival, proliferative, and metabolic pathways within the proinflammatory cellular microenvironment. The recent breakthrough in antiviral therapy using direct-acting antivirals (DAAs) can cure >90% of HCV patients. However, viral cure cannot fully eliminate the HCC risk, especially in patients with advanced liver disease or comorbidities. HCV induces an epigenetic viral footprint that promotes a pro-oncogenic hepatic signature, which persists after DAA cure. In this review, we summarize the main signaling pathways deregulated by HCV infection, with potential impact on liver pathogenesis. HCV-induced persistent signaling patterns may serve as biomarkers for the stratification of HCV-cured patients at high risk of developing HCC. Moreover, these signaling pathways are potential targets for novel chemopreventive strategies.

Liver fibrosis in biliary atresia

BACKGROUND

Biliary atresia (BA) is the most common cause of obstructive jaundice in infants. Although the Kasai procedure has greatly improved the prognosis, most patients still need liver transplantation (LT) for long-term survival. The pathogenesis of BA has not been fully clarified, and liver fibrosis in BA is far beyond biliary obstructive cirrhosis.

DATA SOURCES

Literature reviews were underwent through PubMed. Persistent inflammation, immune response, biliary epithelial-mesenchymal transition, matrix deposition, decompensated angiogenesis, and unique biliary structure development all contribute to the fibrosis process. Observed evidences in such fields have been collected and form the backbone of this review.

RESULTS

Interactions of the multiple pathways accelerate this process.

CONCLUSIONS

Understanding the mechanisms of the liver fibrosis in BA may pave the way to improved survival after the Kasai procedure.

Oncogenic Signaling Induced by HCV Infection

The liver is frequently exposed to toxins, metabolites, and oxidative stress, which can challenge organ function and genomic stability. Liver regeneration is therefore a highly regulated process involving several sequential signaling events. It is thus not surprising that individual oncogenic mutations in hepatocytes do not necessarily lead to cancer and that the genetic profiles of hepatocellular carcinomas (HCCs) are highly heterogeneous. Long-term infection with hepatitis C virus (HCV) creates an oncogenic environment by a combination of viral protein expression, persistent liver inflammation, oxidative stress, and chronically deregulated signaling events that cumulate as a tipping point for genetic stability. Although novel direct-acting antivirals (DAA)-based treatments efficiently eradicate HCV, the associated HCC risk cannot be fully eliminated by viral cure in patients with advanced liver disease. This suggests that HCV may persistently deregulate signaling pathways beyond viral cure and thereby continue to perturb cancer-relevant gene function. In this review, we summarize the current knowledge about oncogenic signaling pathways derailed by chronic HCV infection. This will not only help to understand the mechanisms of hepatocarcinogenesis but will also highlight potential chemopreventive strategies to help patients with a high-risk profile of developing HCC.

Dietary Melatonin Supplementation Could Be a Promising Preventing/Therapeutic Approach for a Variety of Liver Diseases

In the therapeutic strategies, the role of diet is a well-established factor that can also have an important role in liver diseases. Melatonin, identified in animals, has many antioxidant properties and it was after discovered also in plants, named phytomelatonin. These substances have a positive effect during aging and in pathological conditions too. In particular, it is important to underline that the amount of melatonin produced by pineal gland in human decreases during lifetime and its reduction in blood could be related to pathological conditions in which mitochondria and oxidative stress play a pivotal role. Moreover, it has been indicated that melatonin/phytomelatonin containing foods may provide dietary melatonin, so their ingestion through balanced diets could be sufficient to confer health benefits. In this review, the classification of liver diseases and an overview of the most important aspects of melatonin/phytomelatonin, concerning the differences among their synthesis, their presence in foods and their role in health and diseases, are summarized. The findings suggest that melatonin/phytomelatonin supplementation with diet should be considered important in preventing different disease settings, in particular in liver. Currently, more studies are needed to strengthen the potential beneficial effects of melatonin/phytomelatonin in liver diseases and to better clarify the molecular mechanisms of action.

Targeted therapy of chronic liver diseases with the inhibitors of angiogenesis

Angiogenesis appears to be intrinsically associated with the progression of chronic liver diseases, which eventually leads to the development of cirrhosis and related complications, including hepatocellular carcinoma. Several studies have suggested that this association is relevant for chronic liver disease (CLD) progression, with angiogenesis. The fact that angiogenesis plays a pivotal role in CLDs gives rise to new opportunities for treating CLDs. Inhibitor of angiogenesis has proved effective for the treatment of patients suffering from CLD. However, it is limited in diagnosis. The last decade has witnessed a plethora of publications which elucidate the potential of angiogenesis inhibitors for the therapy of CLD. The close relationship between the progression of CLDs and angiogenesis emphasizes the need for anti-angiogenic therapy to block/slow down CLD progression. The present review summarizes all these discussions, the results of the related studies carried out to date and the future prospects in this field. We discuss liver angiogenesis in normal and pathophysiologic conditions with a focus on the role and future use of angiogenic factors as second-line treatment of CLD. This review compiles relevant findings and offers opinions that have emerged in last few years relating liver angiogenesis and its treatment using anti-angiogenic factors.

Underrated enemy - from nonalcoholic fatty liver disease to cancers of the gastrointestinal tract

Nonalcoholic fatty liver disease (NAFLD) is intrahepatic ectopic lipid deposition which is present despite a lack of other causes of secondary hepatic fat accumulation. It is the most common chronic liver disorder in the welldeveloped countries. NAFLD is a multidisciplinary disease that affects various systems and organs and is inextricably linked to simple obesity, metabolic syndrome, insulin resistance and overt diabetes mellitus type 2. The positive energy balance related to obesity leads to a variety of systemic changes including modified levels of insulin, insulin- like growth factor-1, adipokines, hepatokines and cytokines. It is strongly linked to carcinogenesis and new evidence proves that NAFLD is associated with higher risk of all-cause mortality and cancer-specific mortality among cancer survivors. This article focuses on the association between NAFLD and extrahepatic gastrointestinal tract cancers, aiming to shed light on the pathomechanism of changes leading to the development of tumors.

Liver regeneration microenvironment of hepatocellular carcinoma for prevention and therapy

Research on liver cancer prevention and treatment has mainly focused on the liver cancer cells themselves. Currently, liver cancers are no longer viewed as only collections of genetically altered cells but as aberrant organs with a plastic stroma, matrix, and vasculature. Improving the microenvironment of the liver to promote liver regeneration and repair by affecting immune function, inflammation and vasculature can regulate the dynamic imbalance between normal liver regeneration and repair and abnormal liver regeneration, thus improving the microenvironment of liver regeneration for the prevention and treatment of liver cancer. This review addresses the basic theory of the liver regeneration microenvironment, including the latest findings on immunity, inflammation and vasculature. Attention is given to the potential design of molecular targets in the microenvironment of hepatocellular carcinoma (HCC). In an effort to improve the liver regeneration microenvironment of HCC, researchers have extensively utilized the enhancement of immunity, anti-inflammation and the vasculature niche, which are discussed in detail in this review. In addition, the authors summarize the latest pro-fibrotic transition characteristics of the vascular niche and review potential cell therapies for liver disease.

Angiogenesis and Fibrogenesis in Oral Submucous Fibrosis: A Viewpoint

Oral submucous fibrosis (OSF) is characterized by excessive fibrosis of submucosa. The degree of vascularity in OSF has always been a matter of debate. Angiogenesis is the key mechanism involved in regeneration and repair. It also plays an important role in various pathologic conditions. Angiogenesis may contribute to the progression of fibrosis in fibrotic disorders. Inhibition of pathological angiogenesis is considered to be a new strategy for the treatment of various fibrotic disorders. In OSF, angiogenesis can be related to progression fibrosis. This article briefly describes the role of angiogenesis in pathogenesis of fibrosis in OSF and the importance of inhibition of pathologic angiogenesis in its prevention and treatment.

CLINICAL SIGNIFICANCE

Understanding the association between angiogenesis and fibrogenesis can help in developing new therapeutic strategies for treatment of OSF.

Inhibition of canonical WNT signaling pathway by β-catenin/CBP inhibitor ICG-001 ameliorates liver fibrosis in vivo through suppression of stromal CXCL12

Quiescent hepatic stellate cells (HSCs), in response to liver injury, undergo characteristic morphological transformation into proliferative, contractile and ECM-producing myofibroblasts. In this study, we investigated the implication of canonical Wnt signaling pathway in HSCs and liver fibrogenesis. Canonical Wnt signaling pathway activation and inhibition using β-catenin/CBP inhibitor ICG001 was examined in-vitro in TGFβ-activated 3T3, LX2, primary human HSCs, and in-vivo in CCl₄-induced acute liver injury mouse model. Fibroblasts-conditioned medium studies were performed to assess the Wnt-regulated paracrine factors involved in crosstalk between HSCs-macrophages and HSCs-endothelial cells. Canonical Wnt signaling pathway components were significantly up-regulated in-vitro and in-vivo. In-vitro, ICG-001 significantly inhibited fibrotic parameters, 3D-collagen contractility and wound healing. Conditioned medium induced fibroblasts-mediated macrophage and endothelial cells activation was significantly inhibited by ICG-001. In-vivo, ICG-001 significantly attenuated collagen accumulation and HSC activation. Interestingly, ICG-001 drastically inhibited macrophage infiltration, intrahepatic inflammation and angiogenesis. We further analyzed the paracrine factors involved in Wnt-mediated effects and found CXCL12 was significantly suppressed both in-vitro and in-vivo following Wnt inhibition. Wnt-regulated CXCL12 secretion from activated HSCs potentiated macrophage infiltration and activation, and angiogenesis. Pharmacological inhibition of canonical Wnt signaling pathway via suppression of stromal CXCL12 suggests a potential therapeutic approach targeting activated HSCs in liver fibrosis.

Intrahepatic angiopoietin-2 correlates with chronic hepatitis C progression and is induced in hepatitis C virus replicon systems

BACKGROUND & AIMS

Chronic hepatitis C (CHC) is a major cause of cirrhosis and hepatocellular carcinoma and angiogenesis is closely related to the pathogenesis and progression of different chronic liver diseases (CLD). Thus, the intrahepatic expression of angiopoietins 1 and 2 (Ang1 and Ang2), as relevant mediators of pathological angiogenesis in several CLD, was investigated. In addition, the differential influence of structural and non-structural genomic regions of HCV on the expression of angiopoietins and the possible signalling involved were studied.

METHODS

Ang1 and Ang2 expression was evaluated by western blotting and enzyme-linked immunosorbent assay (ELISA) in liver homogenates of CHC patients (n=47) and uninfected subjects (n=8). Their association with disease progression (according to METAVIR classification) was assessed by Spearman's correlation. Statistical differences among the expression of angiopoietins at different CHC stages were calculated by Mann-Whitney U-test. Finally, the in vitro expression of Angiopoietins in HCV replicons (complete or non-structural subgenomic) and the main signalling pathways involved were also examined.

RESULTS

Ang2 levels were significantly higher in the liver of CHC patients compared to controls and significantly correlated with inflammation and fibrosis. Accordingly, an increased expression of Ang2 was found in all HCV replicons tested. Interestingly, the inhibition of MEK and PI3K signalling pathways exerted differential effects on Ang2 expression concerning to the genomic region of HCV.

CONCLUSIONS

Hepatitis C virus induces Ang2 expression in hepatocytes through different signalling routes which may lead to the disregulation of vascular homeostasis in the liver. Thus, pharmacologic intervention on Ang2 signalling might constitute an important therapeutic tool.

Vascular Endothelial Growth Factor Expression in Hepatitis C Virus-Induced Liver Fibrosis: A Potential Biomarker

The major complication of hepatitis C virus (HCV) infection is the induction of hepatic fibrosis. In this study, we investigated the correlation between the expression level of vascular endothelial growth factor (VEGFA) at mRNA and protein levels and the progression of HCV-related liver fibrosis. One hundred twenty subjects were selected for this study: 15 controls and 105 chronic HCV patients with different fibrosis grades (44 F0-F1 and 61 F2-F4). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure VEGFA mRNA in peripheral blood mononuclear cells, while enzyme-linked immunosorbent assay (ELISA) was used to measure the secreted VEGFA protein in serum. Both qRT-PCR and ELISA results showed that HCV patients have significantly higher VEGFA expression than that of controls (P = 0.036 and 0.043, respectively). Moreover, patients with late fibrotic stages (F2-F4) exhibited the highest levels of VEGFA mRNA and protein (P = 0.008 and 0.041, respectively) when compared with controls. An area under the receiver operating characteristic curve (AUC of the ROC) for the circulatory VEGFA protein between HCV patients with fibrosis and healthy controls was 0.92 (P = 0.043). Our data suggest that VEGFA protein is a promising noninvasively diagnostic biomarker for HCV-induced liver fibrosis.

Tyrosine kinase inhibitor BIBF1120 ameliorates inflammation, angiogenesis and fibrosis in CCl4-induced liver fibrogenesis mouse model

Hepatic fibrosis, a progressive chronic disease mainly caused by hepatitis viral infections, alcohol abuse or metabolic syndrome leading to liver dysfunction and is the growing cause of mortality worldwide. Tyrosine kinase inhibitor BIBF1120 (Nintedanib) has been evaluated in clinical trials for idiopathic pulmonary fibrosis and advanced Hepatocellular carcinoma, but has not been explored for liver fibrosis yet. In this study, we aimed to investigate the therapeutic effects and mechanism of BIBF1120 in liver fibrogenesis. The effects of BIBF1120 were evaluated in TGFβ-activated mouse 3T3 fibroblasts, LX2 cells, primary human hepatic stellate cells (HSCs) and CCl₄-induced liver fibrogenesis mouse model. Fibroblasts-conditioned medium studies were performed to assess the paracrine effects on macrophages and endothelial cells. In-vitro in TGFβ-activated fibroblasts, BIBF1120 significantly inhibited expression of major fibrotic parameters, wound-healing and contractility. In vivo in CCl₄-induced acute liver injury model, post-disease BIBF1120 administration significantly attenuated collagen accumulation and HSC activation. Interestingly, BIBF1120 drastically inhibited intrahepatic inflammation and angiogenesis. To further elucidate the mechanism of action, 3T3-conditioned medium studies demonstrated increased 3T3-mediated macrophage chemotaxis and endothelial cells tube formation and activation, which was significantly decreased by BIBF1120. These results suggests that BIBF1120 can be a potential therapeutic approach for the treatment of liver fibrosis.

Contrast-enhanced ultrasonography could be a non-invasive method for differentiating none or mild from severe fibrosis in patients with biopsy proven non-alcoholic fatty liver disease

OBJECTIVE

The gold standard for diagnosing fibrosis stage in non-alcoholic fatty liver disease (NAFLD) is liver biopsy. The aim of this study was to determine whether contrast-enhanced ultrasonography (CEUS) with transit time measurements could be a non-invasive alternative for differentiating none or mild from severe fibrosis in NAFLD patients. Various serum markers and clinical variables were also evaluated.

MATERIALS AND METHODS

Fifty-eight patients with NAFLD underwent CEUS prior to liver biopsy. All patients were also evaluated according to the Göteborg University Cirrhosis Index (GUCI), the AST-Platelet Ratio Index (APRI), the NAFLD fibrosis score, and the FIB-4 and BARD score.

RESULTS

The hepatic vein arrival time (HV) was shorter in patients with severe fibrosis (25.9 ± 4.8 vs 29.5 ± 4.7 s, p = 0.023), and the difference between the hepatic and portal vein (ΔHV-PV) was shorter (2.3 ± 2.8 vs 6.4 ± 2.8 s, p < 0.0001) while the difference in arrival time between the portal vein and hepatic artery (ΔPV-HA) arrival time was significantly longer (6.0 ± 2.2 vs 3.6 ± 1.6 s, p < 0.0001). The area under receiver operating characteristics curve values for HV, ΔHV-PV and ΔPV-HA to separate none or mild from severe fibrosis was 0.71, 0.83 and 0.84, respectively. The corresponding figures for GUCI, APRI, NAFLD fibrosis score, FIB-4 and BARD score were 0.93, 0.92, 0.86, 0.90 and 0.77, respectively.

CONCLUSIONS

CEUS and non-invasive scoring systems could exclude severe fibrosis in NAFLD patients.

A robust method for high-precision quantification of the complex three-dimensional vasculatures acquired by X-ray microtomography

The quantification of micro-vasculatures is important for the analysis of angiogenesis on which the detection of tumor growth or hepatic fibrosis depends. Synchrotron-based X-ray computed micro-tomography (SR-µCT) allows rapid acquisition of micro-vasculature images at micrometer-scale spatial resolution. Through skeletonization, the statistical features of the micro-vasculature can be extracted from the skeleton of the micro-vasculatures. Thinning is a widely used algorithm to produce the vascular skeleton in medical research. Existing three-dimensional thinning methods normally emphasize the preservation of topological structure rather than geometrical features in generating the skeleton of a volumetric object. This results in three problems and limits the accuracy of the quantitative results related to the geometrical structure of the vasculature. The problems include the excessively shortened length of elongated objects, eliminated branches of blood vessel tree structure, and numerous noisy spurious branches. The inaccuracy of the skeleton directly introduces errors in the quantitative analysis, especially on the parameters concerning the vascular length and the counts of vessel segments and branching points. In this paper, a robust method using a consolidated end-point constraint for thinning, which generates geometry-preserving skeletons in addition to maintaining the topology of the vasculature, is presented. The improved skeleton can be used to produce more accurate quantitative results. Experimental results from high-resolution SR-µCT images show that the end-point constraint produced by the proposed method can significantly improve the accuracy of the skeleton obtained using the existing ITK three-dimensional thinning filter. The produced skeleton has laid the groundwork for accurate quantification of the angiogenesis. This is critical for the early detection of tumors and assessing anti-angiogenesis treatments.

Hyperammonemia Is Associated with Increasing Severity of Both Liver Cirrhosis and Hepatic Encephalopathy

Background. Hyperammonemia resulting from chronic liver disease (CLD) can potentially challenge and damage any organ system of the body, particularly the brain. However, there is still some controversy regarding the diagnostic or prognostic values of serum ammonia in patients with over hepatic encephalopathy, especially in the setting of acute-on-chronic or chronic liver failure. Moreover, the association of serum ammonia with worsening Child-Pugh grade of liver cirrhosis has not been studied. Objective. This study was conducted to solve the controversy regarding the association between hyperammonemia and cirrhosis, especially hepatic encephalopathy in chronically failed liver. Material and Methods. In this study, 171 cirrhotic patients had their serum ammonia measured and analyzed by SPSS version 16. Chi-squared test and one-way ANOVA were applied. Results. The study had 110 male and 61 female participants. The mean age of all the participants in years was 42.33 ± 7.60. The mean duration (years) of CLD was 10.15 ± 3.53 while the mean Child-Pugh (CP) score was 8.84 ± 3.30. Chronic viral hepatitis alone was responsible for 71.3% of the cases. Moreover, 86.5% of participants had hepatic encephalopathy (HE). The frequency of hyperammonemia was 67.3%, more frequent in males (N = 81, z-score = 2.4, and P < 0.05) than in females (N = 34, z-score = 2.4, and P < 0.05), and had a statistically significant relationship with increasing CP grade of cirrhosis (χ²(2) = 27.46, P < 0.001, Phi = 0.40, and P < 0.001). Furthermore, serum ammonia level was higher in patients with hepatic encephalopathy than in those without it; P < 0.001. Conclusion. Hyperammonemia is associated with both increasing Child-Pugh grade of liver cirrhosis and hepatic encephalopathy.

APRi predicts native liver survival by reflecting portal fibrogenesis and hepatic neovascularization at the time of portoenterostomy in biliary atresia

BACKGROUND

Aspartate aminotransferase-to-platelet ratio index (APRi) may be useful noninvasive prognostic tool in biliary atresia (BA). We studied whether APRi predicts native liver survival and parallels biochemical and immunohistological signs of liver injury and fibrogenesis at the time of Kasai portoenterostomy (PE).

METHODS

Serum and liver specimens were obtained at PE from 29 BA patients for liver biochemistry including APRi, histology and immunohistochemical analysis of collagen 1, α-SMA and CD34. APRi values were related to native liver survival and other clinical data as well as serum liver biochemistry, liver histology and immunohistochemistry at PE.

RESULTS

Median age at PE was 63 (range 7-141) days and median APRi was 0.92 (0.13-6.39). APRi had strong positive correlations with patient age (r=0.684, p<0.001) and biochemical signs of hepatocyte injury and cholestasis. APRi showed no significant correlations with Metavir (r=0.336, p=0.223) or Ishak (r=0.289, p=0.262) global fibrosis scores nor with liver collagen 1 expression (r=0.260, p=0.222). In contrast, portal fibrosis score (r=0.515, p=0.013), predominantly portal α-SMA expression (r=0.519, p=0.015) and amount CD34-positive microvessels in the centrizonal region (r=0.604, p=0.004) correlated positively with APRi. Patients (n=10) who underwent liver transplantation had significantly higher APRi at presentation (1.34 vs. 0.77, p=0.017) compared to those who survived with native liver (n=19).

CONCLUSIONS

APRi correlates with portal fibrosis, expression of α-SMA and the amount of CD34-positive microvessels, suggesting that APRi predicts native liver survival by reflecting portal myofibroblastic cell activation, fibrogenesis and associated neovascularization.

The role of iNOS in cholesterol-induced liver fibrosis

Accumulation of cholesterol in the liver is associated with the development of non-alcoholic steatohepatitis-related fibrosis. However, underlying mechanisms are not well understood. The present study investigated the role of inducible nitric oxide synthase (iNOS) in cholesterol-induced liver fibrosis by feeding wild-type (WT) and iNOS-deficient mice with control or high-cholesterol diet (HCD) for 6 weeks. WT mice fed with HCD developed greater liver fibrosis, compared with iNOS-deficient mice, as evident by Sirius red staining and higher expression levels of profibrotic genes. Enhanced liver fibrosis in the presence of iNOS was associated with hypoxia-inducible factor-1α stabilization, matrix metalloproteinase-9 expression, and enhanced hepatic DNA damage. The profibrotic role of iNOS was also demonstrated in vivo using a selective inhibitor of iNOS as well as in vitro in a rat liver stellate cell line (HSC-T6). In conclusion, these findings suggest that iNOS is an important mediator in HCD-induced liver fibrosis.

The role of miRNAs in stress-responsive hepatic stellate cells during liver fibrosis

The progression of liver fibrosis and cirrhosis is associated with the persistence of an injury causing agent, leading to changes in the extracellular environment and a disruption of the cellular homeostasis of liver resident cells. Recruitment of inflammatory cells, apoptosis of hepatocytes, and changes in liver microvasculature are some examples of changing cellular environment that lead to the induction of stress responses in nearby cells. During liver fibrosis, the major stresses include hypoxia, oxidative stress, and endoplasmic reticulum stress. When hepatic stellate cells (HSCs) are subjected to such stress, they modulate fibrosis progression by induction of their activation toward a myofibroblastic phenotype, or by undergoing apoptosis, and thus helping fibrosis resolution. It is widely accepted that microRNAs are import regulators of gene expression, both during normal cellular homeostasis, as well as in pathologic conditions. MicroRNAs are short RNA sequences that regulate the gene expression by mRNA destabilization and inhibition of mRNA translation. Specific microRNAs have been identified to play a role in the activation process of HSCs on the one hand and in stress-responsive pathways on the other hand in other cell types (Table 2). However, so far there are no reports for the involvement of miRNAs in the different stress responses linked to HSC activation. Here, we review briefly the major stress response pathways and propose several miRNAs to be regulated by these stress responsive pathways in activating HSCs, and discuss their potential specific pro-or anti-fibrotic characteristics.

Resolution of liver fibrosis requires myeloid cell-driven sinusoidal angiogenesis

Angiogenesis is a key feature of liver fibrosis. Although sinusoidal remodeling is believed to contribute to fibrogenesis, the impact of sinusoidal angiogenesis on the resolution of liver fibrosis remains undefined. Myeloid cells, particularly macrophages, constantly infiltrate the fibrotic liver and can profoundly contribute to remodeling of liver sinusoids. We observe that the development of fibrosis is associated with decreased hepatic vascular endothelial growth factor (VEGF) expression as well as sinusoidal rarefication of the fibrotic scar. In contrast, the resolution of fibrosis is characterized by a rise in hepatic VEGF levels and revascularization of the fibrotic tissue. Genetic ablation of VEGF in myeloid cells or pharmacological inhibition of VEGF receptor 2 signaling prevents this angiogenic response and the resolution of liver fibrosis. We observe increased expression of matrix metalloproteases as well as decreased expression of tissue inhibitor of metalloproteases confined to sinusoidal endothelial cells in response to myeloid cell VEGF. Remarkably, reintroduction of myeloid cell-derived VEGF upon recovery restores collagenolytic acitivity and the resolution of fibrosis.

CONCLUSION

We identify myeloid cell-derived VEGF as a critical regulator of extracellular matrix degradation by liver endothelial cells, thereby unmasking an unanticipated link between angiogenesis and the resolution of fibrosis.

Hepatic fibrosis and angiogenesis after bile duct ligation are endogenously expressed vasohibin-1 independent

Liver fibrosis is linked to VEGF-induced angiogenesis. Overexpression of exogenous vasohibin-1, a feedback inhibitor of angiogenesis, has been reported to reduce liver fibrosis after bile duct ligation (BDL). To uncover the function of endogenous vasohibin-1, we performed BDL using vasohibin-1-deficient mice and analyzed liver fibrosis, injury, and angiogenesis. Liver fibrosis was induced by 14-days of BDL in both wild-type and vasohibin-1-deficient mice. The liver sections were stained with anti-CD31 to visualize endothelial cells and with Sirius red to observe fibrotic regions. Total RNAs were purified from the livers and expression of collagen I α1 mRNA was measured by quantitative PCR. Plasma ALT activity was determined to assess liver injury. Surprisingly, the same extents of increases were seen in anti-CD31 and Sirius red stainings, collagen I α1 mRNA expressions, hepatic hydroxyproline contents, and ALT activity after 14-days of BDL in both wild-type and vasohibin-1-deficient mice. There was unexpectedly no difference between these mice, suggesting that anti-fibrogenic and angiogenic activities of the endogenous vasohibin-1 might be masked in the normal liver at early stage of hepatic fibrosis in mice.

Transarterial chemoembolization aggravated peritumoral fibrosis via hypoxia-inducible factor-1α dependent pathway in hepatocellular carcinoma

BACKGROUND AND AIM

It was commonly accepted that chemotherapeutic cytotoxicity was the main cause for hepatic failure in hepatocellular carcinoma patients after repeated transarterial chemoembolization (TACE). However, the effect of embolization-induced hypoxia on liver cirrhosis has rarely been concerned.

METHODS

Serum levels of alanine aminotransferase, aspartate aminotransferase, and albumin were used to detect liver injury. Hepatic artery ligation was performed in carbon tetrachloride-induced rat hepatic fibrosis model to mimic the effect of hepatic hypoxia on liver fibrosis after TACE. Sirius Red staining and immunohistochemical analysis of alpha-smooth muscle actin (α-SMA) were used to detect the activation of hepatic stellate cells. Moreover, the expression of hypoxia and fibrosis-related molecules were analyzed at protein and/or mRNA level.

RESULTS

Patients showed a significant increase in alanine aminotransferase and aspartate aminotransferase (P = 0.006), accompanied by a decrease in albumin (P = 0.005) after repeated TACE. Hepatic artery ligation significantly promoted carbon tetrachloride-induced rat liver fibrosis progression as indicated by Sirius Red and α-SMA staining, as well as increased expression of hypoxia-inducible factor (HIF)-1α, transforming growth factor (TGF)-β1, and vascular endothelial growth factor (VEGF). Conditioned media of hypoxia-treated L02 cells induced the expression of Collagen I and α-SMA in LX-2 cells, which was inhibited by HIF-1α small interfering RNA. Finally, HIF-1α inhibitor LW6 attenuated the hypoxia-induced fibrosis progression in vivo.

CONCLUSION

Our data demonstrate that TACE-induced hepatic hypoxia aggravates the fibrosis progression in peritumoral liver tissue, thus leads to the deterioration of liver function. Intervention of HIF-1α might be a valuable strategy to optimize the efficacy and reduce the complication of TACE.

Aqueous Date Flesh or Pits Extract Attenuates Liver Fibrosis via Suppression of Hepatic Stellate Cell Activation and Reduction of Inflammatory Cytokines, Transforming Growth Factor- β 1 and Angiogenic Markers in Carbon Tetrachloride-Intoxicated Rats

Previous data indicated the protective effect of date fruit extract on oxidative damage in rat liver. However, the hepatoprotective effects via other mechanisms have not been investigated. This study was performed to evaluate the antifibrotic effect of date flesh extract (DFE) or date pits extract (DPE) via inactivation of hepatic stellate cells (HSCs), reducing the levels of inflammatory, fibrotic and angiogenic markers. Coffee was used as reference hepatoprotective agent. Liver fibrosis was induced by injection of CCl₄ (0.4 mL/kg) three times weekly for 8 weeks. DFE, DPE (6 mL/kg), coffee (300 mg/kg), and combination of coffee + DFE and coffee + DPE were given to CCl₄-intoxicated rats daily for 8 weeks. DFE, DPE, and their combination with coffee attenuated the elevated levels of inflammatory cytokines including tumor necrosis factor-α, interleukin-6, and interleukin-1β. The increased levels of transforming growth factor-β1 and collagen deposition in injured liver were alleviated by both extracts. CCl₄-induced expression of α-smooth muscle actin was suppressed indicating HSCs inactivation. Increased angiogenesis was ameliorated as revealed by reduced levels and expression of vascular endothelial growth factor and CD31. We concluded that DFE or DPE could protect liver via different mechanisms. The combination of coffee with DFE or DPE may enhance its antifibrotic effects.

Angiogenesis and liver fibrosis

Recent data indicate that hepatic angiogenesis, regardless of the etiology, takes place in chronic liver diseases (CLDs) that are characterized by inflammation and progressive fibrosis. Because anti-angiogenic therapy has been found to be efficient in the prevention of fibrosis in experimental models of CLDs, it is suggested that blocking angiogenesis could be a promising therapeutic option in patients with advanced fibrosis. Consequently, efforts are being directed to revealing the mechanisms involved in angiogenesis during the progression of liver fibrosis. Literature evidences indicate that hepatic angiogenesis and fibrosis are closely related in both clinical and experimental conditions. Hypoxia is a major inducer of angiogenesis together with inflammation and hepatic stellate cells. These profibrogenic cells stand at the intersection between inflammation, angiogenesis and fibrosis and play also a pivotal role in angiogenesis. This review mainly focuses to give a clear view on the relevant features that communicate angiogenesis with progression of fibrosis in CLDs towards the-end point of cirrhosis that may be translated into future therapies. The pathogenesis of hepatic angiogenesis associated with portal hypertension, viral hepatitis, non-alcoholic fatty liver disease and alcoholic liver disease are also discussed to emphasize the various mechanisms involved in angiogenesis during liver fibrogenesis.

Combination of sorafenib and angiotensin-II receptor blocker attenuates preneoplastic lesion development in a non-diabetic rat model of steatohepatitis

BACKGROUND

Given the well-documented adverse side effects of sorafenib, many sorafenib-treated patients may need the reduced initial dose of the compound, and an alternative sorafenib-based therapy, which exerts similar clinical benefit, is anticipated. An angiostatic therapy with sorafenib is considered one of the promising approaches for chemoprevention of hepatocellular carcinoma. The aim of the current study was to elucidate the combination effect of low dose of sorafenib and angiotensin-II receptor blocker (ARB) on hepatocarcinogenesis, especially in conjunction with angiogenesis.

METHODS

The chemopreventive effect on the development of liver preneoplastic lesions, angiogenesis, and several indices was elucidated in rats. We also performed several sets of in vitro experiments to examine the mechanisms involved.

RESULTS

Using a non-diabetic rat model of steatohepatitis with choline deficient L-amino acid-defined diet, sorafenib demonstrated marked inhibition of preneoplastic lesions in a dose dependent manner. Combined treatment with ARB (losartan) at a clinically comparable dose and half dose of sorafenib resulted in the inhibitory effect equivalent to that of common dose of sorafenib along with suppression of hepatic neovascularization and potent angiogenic factor, vascular endothelial growth factor. Furthermore, similar combined inhibitory outcomes were observed in several sets of in vitro studies.

CONCLUSION

Since the combinatorial treatment using low doses of sorafenib and ARB could sufficiently induce inhibitory effect on the development of preneoplastic lesions at the magnitude similar to the conventional dose of sorafenib, this regimen may provide new strategy for patients intolerant of the usual dose of sorafenib in the future.