Hepatic stellate cell: a star cell in the liver

Mouse liver blood flow is regulated by hepatic stellate cells in response to the sympathetic neurotransmitter norepinephrine

BACKGROUND

There is no clear information on the regulation of liver blood flow by the autonomic nervous system. We conducted this study to investigate whether quiescent hepatic stellate cells (qHSCs) regulate liver blood flow in response to the sympathetic neurotransmitter norepinephrine (NE).

METHODS

qHSCs isolated from mice were cultured in Dulbecco's modified Eagle medium without fetal bovine serum for 1 day on collagen gel. NE-induced qHSC contraction was evaluated using the quantitative single-cell contraction measurement method that we had developed previously. For the measurement of liver perfusion pressure in situ, a buffer solution was perfused from the portal vein in mice.

RESULTS

NE-induced a reversible contraction of qHSCs. This contraction was suppressed by the nonmuscle myosin II inhibitor blebbistatin, the myosin light chain kinase inhibitor ML-9, the Rho kinase inhibitor H-1152, the calmodulin inhibitor W-7, the store-operated calcium channel inhibitor YM-58483, and the IP3 receptor inhibitor xestospongin C. In contrast, the transient receptor potential C channel inhibitor SKF96365 did not affect the NE-induced contraction.

CONCLUSION

These results suggest that qHSCs contract in response to NE.

NEW & NOTEWORTHY

The present study provides direct evidence for the first time that norepinephrine (NE) induces a reversible contraction of isolated single quiescent hepatic stellate cells (qHSCs) and further suggests that the NE-mediated qHSC contraction participates in the regulation of liver blood flow in vivo.

Depletion of Activated Hepatic Stellate Cells and Capillarized Liver Sinusoidal Endothelial Cells Using a Rationally Designed Protein for Nonalcoholic Steatohepatitis and Alcoholic Hepatitis Treatment

Nonalcoholic steatohepatitis (NASH) and alcoholic hepatitis (AH) affect a large part of the general population worldwide. Dysregulation of lipid metabolism and alcohol toxicity drive disease progression by the activation of hepatic stellate cells and the capillarization of liver sinusoidal endothelial cells. Collagen deposition, along with sinusoidal remodeling, alters sinusoid structure, resulting in hepatic inflammation, portal hypertension, liver failure, and other complications. Efforts were made to develop treatments for NASH and AH. However, the success of such treatments is limited and unpredictable. We report a strategy for NASH and AH treatment involving the induction of integrin αvβ3-mediated cell apoptosis using a rationally designed protein (ProAgio). Integrin αvβ3 is highly expressed in activated hepatic stellate cells (αHSCs), the angiogenic endothelium, and capillarized liver sinusoidal endothelial cells (caLSECs). ProAgio induces the apoptosis of these disease-driving cells, therefore decreasing collagen fibril, reversing sinusoid remodeling, and reducing immune cell infiltration. The reversal of sinusoid remodeling reduces the expression of leukocyte adhesion molecules on LSECs, thus decreasing leukocyte infiltration/activation in the diseased liver. Our studies present a novel and effective approach for NASH and AH treatment.

Liver Fibrosis Stages Affect Organic Cation Transporter 1/2 Activities in Hepatitis C Virus-Infected Patients

This study aims to evaluate the impact of liver fibrosis stages of chronic infection with hepatitis C virus (HCV) on the in vivo activity of organic cation transporters (hepatic OCT1 and renal OCT2) using metformin (MET) as a probe drug. Participants allocated in Group 1 (n = 15, mild to moderate liver fibrosis) or 2 (n = 13, advanced liver fibrosis and cirrhosis) received a single MET 50 mg oral dose before direct-acting antiviral (DAA) drug treatment (Phase 1) and 30 days after achieving sustained virologic response (Phase 2). OCT1/2 activity (MET AUC0-24) was found to be reduced by 25% when comparing the two groups in Phase 2 (ratio 0.75 (0.61-0.93), p < 0.05) but not in Phase 1 (ratio 0.81 (0.66-0.98), p > 0.05). When Phases 1 and 2 were compared, no changes were detected in both Groups 1 (ratio 1.10 (0.97-1.24), p > 0.05) and 2 (ratio 1.03 (0.94-1.12), p > 0.05). So, this study shows a reduction of approximately 25% in the in vivo activity of OCT1/2 in participants with advanced liver fibrosis and cirrhosis after achieving sustained virologic response and highlights that OCT1/2 in vivo activity depends on the liver fibrosis stage of chronic HCV infection.

PEI-based functional materials: Fabrication techniques, properties, and biomedical applications

Cationic polymers have recently attracted considerable interest as research breakthroughs for various industrial and biomedical applications. They are particularly interesting due to their highly positive charges, acceptable physicochemical properties, and ability to undergo further modifications, making them attractive candidates for biomedical applications. Polyethyleneimines (PEIs), as the most extensively utilized polymers, are one of the valuable and prominent classes of polycations. Owing to their flexible polymeric chains, broad molecular weight (MW) distribution, and repetitive structural units, their customization for functional composites is more feasible. The specific beneficial attributes of PEIs could be introduced by purposeful functionalization or modification, long service life, biocompatibility, and distinct geometry. Therefore, PEIs have significant potential in biotechnology, medicine, and bioscience. In this review, we present the advances in PEI-based nanomaterials, their transfection efficiency, and their toxicity over the past few years. Furthermore, the potential and suitability of PEIs for various applications are highlighted and discussed in detail. This review aims to inspire readers to investigate innovative approaches for the design and development of next-generation PEI-based nanomaterials possessing cutting-edge functionalities and appealing characteristics.

MANF brakes TLR4 signaling by competitively binding S100A8 with S100A9 to regulate macrophage phenotypes in hepatic fibrosis

The mesencephalic astrocyte-derived neurotrophic factor (MANF) has been recently identified as a neurotrophic factor, but its role in hepatic fibrosis is unknown. Here, we found that MANF was upregulated in the fibrotic liver tissues of the patients with chronic liver diseases and of mice treated with CCl4. MANF deficiency in either hepatocytes or hepatic mono-macrophages, particularly in hepatic mono-macrophages, clearly exacerbated hepatic fibrosis. Myeloid-specific MANF knockout increased the population of hepatic Ly6Chigh macrophages and promoted HSCs activation. Furthermore, MANF-sufficient macrophages (from WT mice) transfusion ameliorated CCl4-induced hepatic fibrosis in myeloid cells-specific MANF knockout (MKO) mice. Mechanistically, MANF interacted with S100A8 to competitively block S100A8/A9 heterodimer formation and inhibited S100A8/A9-mediated TLR4-NF-κB signal activation. Pharmacologically, systemic administration of recombinant human MANF significantly alleviated CCl4-induced hepatic fibrosis in both WT and hepatocytes-specific MANF knockout (HKO) mice. This study reveals a mechanism by which MANF targets S100A8/A9-TLR4 as a "brake" on the upstream of NF-κB pathway, which exerts an impact on macrophage differentiation and shed light on hepatic fibrosis treatment.

Unraveling the Emerging Niche Role of Hepatic Stellate Cell-derived Exosomes in Liver Diseases

Hepatic stellate cells (HSCs) play an essential role in various liver diseases, and exosomes are critical mediators of intercellular communication in local and distant microenvironments. Cellular crosstalk between HSCs and surrounding multiple tissue-resident cells promotes or inhibits the activation of HSCs. Substantial evidence has revealed that HSC-derived exosomes are involved in the occurrence and development of liver diseases through the regulation of retinoid metabolism, lipid metabolism, glucose metabolism, protein metabolism, and mitochondrial metabolism. HSC-derived exosomes are underpinned by vehicle molecules, such as mRNAs and microRNAs, that function in, and significantly affect, the processes of various liver diseases, such as acute liver injury, alcoholic liver disease, nonalcoholic fatty liver disease, viral hepatitis, fibrosis, and cancer. As such, numerous exosomes derived from HSCs or HSC-associated exosomes have attracted attention because of their biological roles and translational applications as potential targets for therapeutic targets. Herein, we review the pathophysiological and metabolic processes associated with HSC-derived exosomes, their roles in various liver diseases and their potential clinical application.

Knockout of ICAT in Adipose Tissue Alleviates Fibro-inflammation in Obese Mice

The E2 promoter binding factor 1 (E2F1) and the Wnt/β-catenin signaling are crucial in regulating metabolic homeostasis including obesity. The β-catenin interacting protein 1 (CTNNBIP1), also known as the inhibitor of β-catenin and TCF4 (ICAT), is required for E2F1 to inhibit the activity of β-catenin. However, the role of ICAT in E2F1 regulating obesity-related metabolic disorders remains unknown. In the present study, male adipose tissue-specific ICAT knockout (ICAT^adi-/-) C57BL/6 J mice and control littermates aged 6-8 weeks were fed with high-fat diet (HFD) for 12 weeks to explore the effect of ICAT on lipid metabolism and obesity-related disorders. Results showed that the adipose tissue-specific ICAT knockout had negligible effect on lipid metabolism, reflected by no difference in body weight, fat mass, and the expression of proteins involved in lipid metabolism in white adipose tissue (WAT) and the liver between the ICAT^adi-/- mice and the control littermate (ICAT^fl/fl) mice. However, the knockout of ICAT reduced inflammatory response in WAT and the liver. Additionally, Sirius red staining results showed that deletion of ICAT attenuated fibrosis and reduced mRNA levels of transforming growth factor β1(TGF-β1), matrix metallopeptidase 2 (Mmp2), Mmp3, and collagen, type V, alpha 1 (Col5a1) in WAT and the liver. These results suggested that knockout of ICAT improved the metabolic abnormalities of obese mice through attenuating adipose tissue and the liver inflammation as well as fibrosis. Our findings may provide a new insight to understand the role of ICAT in inflammation and fibrosis.

The Fibrotic Effects of LINC00663 in Human Hepatic Stellate LX-2 Cells and in Bile Duct-Ligated Cholestasis Mice Are Mediated through the Splicing Factor 2-Fibronectin

Hepatic fibrosis can develop into cirrhosis or even cancer without active therapy at an early stage. Long non-coding RNAs (lncRNAs) have been shown to be involved in the regulation of a wide variety of important biological processes. However, lncRNA mechanism(s) involved in cholestatic liver fibrosis remain unclear. RNA sequence data of hepatic stellate cells from bile duct ligation (BDL) mice or controls were analyzed by weighted gene co-expression network analysis (WGCNA). Based on WGCNA analysis, a competing endogenous RNA network was constructed. We identified LINC00663 and evaluated its function using a panel of assays, including a wound healing assay, a dual-luciferase reporter assay, RNA binding protein immunoprecipitation and chromatin immunoprecipitation. Functional research showed that LINC00663 promoted the activation, migration and epithelial-mesenchymal transition (EMT) of LX-2 cells and liver fibrosis in BDL mice. Mechanistically, LINC00663 regulated splicing factor 2 (SF2)-fibronectin (FN) alternative splicing through the sponging of hsa-miR-3916. Moreover, forkhead box A1 (FOXA1) specifically interacted with the promoter of LINC00663. In summary, we elaborated the fibrotic effects of LINC00663 in human hepatic stellate LX-2 cells and in bile duct-ligated cholestasis mice. We established a FOXA1/LINC00663/hsa-miR-3916/SF2-FN axis that provided a potential target for the diagnosis and targeted therapy of cholestatic liver fibrosis.

20-Hydroxytetraenoic acid induces hepatic fibrosis via the TGF-β1/Smad3 signaling pathway

Hepatic fibrosis is caused by excessive accumulation of extracellular matrix (ECM) due to repeated liver injury. Hepatic stellate cells (HSCs) play a key role in the pathogenesis and progression of hepatic fibrosis. A study showed that CYP4A14 gene defect can inhibit hepatic fibrosis, but the specific mechanism was not clear. In this experiment, patients with hepatic fibrosis, LX-2 cells (a human HSCs line), and mice with liver fibrosis induced by carbon tetrachloride (CCl₄) were used to study the effect of 20-Hydroxytetraenoic acid (20-HETE), one of the main metabolites of arachidonic acid (AA) catalyzed by CYP4A enzyme, on hepatic fibrosis and its mechanism. Our experimental results showed that the 20-HETE of patients with hepatic fibrosis is significantly higher than that of normal people and is closely related to the degree of fibrosis. 20-HETE could induce activation of LX-2 cells and 20-HETE antagonist could inhibit the induction of 20-HETE. 20-HETE was significantly increased in CCl₄-induced liver fibrosis mice and inhibition of 20-HETE production could attenuate hepatic fibrosis. 20-HETE induced hepatic fibrosis mainly via the TGF- β1/Smad3 signal pathway. In conclusion, the results suggest that 20-HETE plays an important role in hepatic fibrosis and may be a possible target for the clinical treatment of hepatic fibrosis.

MicroRNA-181b promotes schistosomiasis-induced hepatic fibrosis by targeting Smad7

Schistosomiasis is a common parasitic disease. Hepatosplenic schistosomiasis, caused by Schistosoma japonicum and Schistosoma mansoni, involves pathological changes, including worm egg-induced hepatic granuloma and fibrosis, which can markedly affect the liver's physiological functions. Although the drug praziquantel (PZQ) is used to treat schistosomiasis, drugs against schistosomiasis-induced liver fibrosis are rare in the clinical setting. Therefore, developing effective strategies to prevent and treat schistosomiasis-induced liver fibrosis is crucial. Previous studies have shown that miRNAs are involved in various liver diseases. In this study, we found a gradual increase in miR-181b expression in the murine liver as S. japonicum infection progressed, while the expression of Smad7 decreased. Down-regulating miR-181b significantly alleviated S. japonicum-induced hepatic granuloma and liver fibrosis. In vitro experiments showed that treatment with TGF-β1 upregulated miR-181b levels in the hepatic stellate cell (HSC) line LX2 in a concentration- and time-dependent manner. Downregulation of miR-181b significantly decreased collagen type I alpha 1 chain (COL1A1) expression in TGF-β1-stimulated LX2 cells. These findings indicate that miR-181b promotes HSC activation by down-regulating Smad7 expression, activating the TGF-β1/Smad signaling pathway, and leading to excess collagen expression and deposition. Our findings suggest that miR-181b might be a potentially novel therapeutic target for schistosomiasis-induced liver fibrosis.

Mesenchymal Stem Cells Influence Activation of Hepatic Stellate Cells, and Constitute a Promising Therapy for Liver Fibrosis

Liver fibrosis is a common feature of chronic liver disease. Activated hepatic stellate cells (HSCs) are the main drivers of extracellular matrix accumulation in liver fibrosis. Hence, a strategy for regulating HSC activation is crucial in treating liver fibrosis. Mesenchymal stem cells (MSCs) are multipotent stem cells derived from various post-natal organs. Therapeutic approaches involving MSCs have been studied extensively in various diseases, including liver disease. MSCs modulate hepatic inflammation and fibrosis and/or differentiate into hepatocytes by interacting directly with immune cells, HSCs, and hepatocytes and secreting modulators, thereby contributing to reduced liver fibrosis. Cell-free therapy including MSC-released secretomes and extracellular vesicles has elicited extensive attention because they could overcome MSC transplantation limitations. Herein, we provide basic information on hepatic fibrogenesis and the therapeutic potential of MSCs. We also review findings presenting the effects of MSC itself and MSC-based cell-free treatments in liver fibrosis, focusing on HSC activation. Growing evidence supports the anti-fibrotic function of either MSC itself or MSC modulators, although the mechanism underpinning their effects on liver fibrosis has not been established. Further studies are required to investigate the detailed mechanism explaining their functions to expand MSC therapies using the cell itself and cell-free treatments for liver fibrosis.

Extracellular PKM2 facilitates organ-tissue fibrosis progression

Persistent activation of fibroblasts and resistance of myofibroblasts to turnover play important roles in organ-tissue fibrosis development and progression. The mechanism that mediates apoptosis resistance of myofibroblasts is not understood. Here, we report that myofibroblasts express and secrete PKM2. Extracellular PKM2 (EcPKM2) facilitates progression of fibrosis by protecting myofibroblasts from apoptosis. EcPKM2 upregulates arginase-1 expression in myofibroblasts and therefore facilitates proline biosynthesis and subsequent collagen production. EcPKM2 interacts with integrin αvβ3 on myofibroblasts to activate FAK-PI3K signaling axis. Activation of FAK-PI3K by EcPKM2 activates downstream NF-κB survival pathway to prevent myofibroblasts from apoptosis. On the other hand, activation of FAK- PI3K by EcPKM2 suppresses PTEN to subsequently upregulate arginase-1 in myofibroblasts. Our studies uncover an important mechanism for organ fibrosis progression. More importantly, an antibody disrupting the interaction between PKM2 and integrin αvβ3 is effective in reversing fibrosis, suggesting a possible therapeutic strategy and target for treatment of organ fibrosis.

Targeting integrin αvβ3 by a rationally designed protein for chronic liver disease treatment

Chronic Liver Diseases (CLD) are characterized by abnormal accumulation of collagen fibrils, neo-angiogenesis, and sinusoidal remodeling. Collagen deposition along with intrahepatic angiogenesis and sinusoidal remodeling alters sinusoid structure resulting in portal hypertension, liver failure, and other complications. Efforts were made to develop treatments for CLDs. However, the success of such treatments is limited and unpredictable. We report a strategy for CLD treatment by induction of integrin αvβ3 mediated cell apoptosis using a rationally designed protein (ProAgio). ProAgio is designed to target integrin αvβ3 at a novel site. Integrin αvβ3 is highly expressed in activated Hepatic Stellate Cells (HSC), angiogenic endothelium, and capillarized Liver Sinusoidal Endothelial Cells (LSEC). ProAgio induces apoptosis of these disease causative cells. Tests with liver fibrosis mouse models demonstrate that ProAgio reverses liver fibrosis and relieves blood flow resistance by depleting activated HSC and capillarized LSEC. Our studies demonstrate an effective approach for CLD treatment.

Role of the sympathetic nervous system in cardiometabolic control: implications for targeted multiorgan neuromodulation approaches

Sympathetic overdrive plays a key role in the perturbation of cardiometabolic homeostasis. Diet-induced and exercise-induced weight loss remains a key strategy to combat metabolic disorders, but is often difficult to achieve. Current pharmacological approaches result in variable responses in different patient cohorts and long-term efficacy may be limited by medication intolerance and nonadherence. A clinical need exists for complementary therapies to curb the burden of cardiometabolic diseases. One such approach may include interventional sympathetic neuromodulation of organs relevant to cardiometabolic control. The experience from catheter-based renal denervation studies clearly demonstrates the feasibility, safety and efficacy of such an approach. In analogy, denervation of the common hepatic artery is now feasible in humans and may prove to be similarly useful in modulating sympathetic overdrive directed towards the liver, pancreas and duodenum. Such a targeted multiorgan neuromodulation strategy may beneficially influence multiple aspects of the cardiometabolic disease continuum offering a holistic approach.

LncRNA-SNHG7/miR-29b/DNMT3A axis affects activation, autophagy and proliferation of hepatic stellate cells in liver fibrosis

OBJECTIVES

To determine the relative expression of long non-coding small nucleolar RNA host gene 7 (lncRNA-SNHG7) in fibrotic liver and hepatic stellate cells, and investigate the biological effects and mechanisms of SNHG7 on liver fibrosis.

METHODS

Liver fibrosis model of mice was established, primary hepatic stellate cells (HSCs) were cultured from normal mice and induced to activate by TGF-β. Cell viability, proliferation, and autophagy were detected with MTT, BrdU, and MDC stain, respectively. Liver tissue stained with Masson and Sirius Red. The interaction between SNHG7 and miR-29b was investigated by immunoprecipitation, RNA pull-down and Dual-luciferase reporter gene assay. The effects of SNHG7 on the expression of miR-29b, DNMT3A and liver fibrosis related factors were detected in vitro or in vivo transfection experiments.

RESULTS

SNHG7 was signally increased in liver tissue and HSCs of liver fibrosis model of mice, and inhibition of SNHG7 expression in liver fibrosis mice can reduce liver fibrosis. We also found that SNHG7 could bind to miR-29b in HSCs and inhibit the expression of miR-29b. In TGF-β-stimulated normal HSCs, knockdown of SNHG7 expression after shSNHG7 transfection could restrain DNMT3A and HSCs activation factors α-SMA, Collα1 and autophagy-related factors LC3I/II, Beclin1. However, this shSNHG7 effect was reversed by the inhibition of miR-29b.

CONCLUSION

Inhibition of lncRNA-SNHG7 can inhibit liver fibrosis. This is partly due to SNHG7 acts as a competitive endogenous RNA (ceRNA) to affect the expression of DNMT3A, a downstream target gene of miR-29b, by binding to miR-29b, thereby affecting the activation, autophagy and proliferation of HSCs.

Optimization of the isolation procedure and culturing conditions for hepatic stellate cells obtained from mouse

Liver fibrosis (LF) mortality rate is approximately 2 million per year. Irrespective of the etiology of LF, a key element in its development is the transition of hepatic stellate cells (HSCs) from a quiescent phenotype to a myofibroblast-like cell with the production of fibrotic proteins. It is necessary to define optimal isolation and culturing conditions for good HSCs yield and proper phenotype preservation for studying the activation of HSCs in vitro. In the present study, the optimal conditions of HSC isolation and culture were examined to maintain the HSC’s undifferentiated phenotype. HSCs were isolated from Balb/c mice liver using Nycodenz, 8, 9.6, and 11%. The efficiency of the isolation procedure was evaluated by cell counting and purity determination by flow cytometry. Quiescent HSCs were cultured in test media supplemented with different combinations of fetal bovine serum (FBS), glutamine (GLN), vitamin A (vitA), insulin, and glucose. The cells were assessed at days 3 and 7 of culture by evaluating the morphology, proliferation using cell counting kit-8, lipid storage using Oil Red O (ORO) staining, expression of a-smooth muscle actin, collagen I, and lecithin-retinol acyltransferase by qRT-PCR and immunocytochemistry (ICC). The results showed that Nycodenz, at 9.6%, yielded the best purity and quantity of HSCs. Maintenance of HSC undifferentiated phenotype was achieved optimizing culturing conditions (serum-free Dulbecco’s Modified Eagle’s Medium (DMEM) supplemented with glucose (100 mg/dl), GLN (0.5 mM), vitA (100 μM), and insulin (50 ng/ml)) with a certain degree of proliferation allowing their perpetuation in culture. In conclusion, we have defined optimal conditions for HSCs isolation and culture.

Gaining New Biological and Therapeutic Applications into the Liver with 3D In Vitro Liver Models

BACKGROUND

Three-dimensional (3D) cell cultures with architectural and biomechanical properties similar to those of natural tissue have been the focus for generating liver tissue. Microarchitectural organization is believed to be crucial to hepatic function, and 3D cell culture technologies have enabled the construction of tissue-like microenvironments, thereby leading to remarkable progress in vitro models of human tissue and organs. Recently, to recapitulate the 3D architecture of tissues, spheroids and organoids have become widely accepted as new practical tools for 3D organ modeling. Moreover, the combination of bioengineering approach offers the promise to more accurately model the tissue microenvironment of human organs. Indeed, the employment of sophisticated bioengineered liver models show long-term viability and functional enhancements in biochemical parameters and disease-orient outcome.

RESULTS

Various 3D in vitro liver models have been proposed as a new generation of liver medicine. Likewise, new biomedical engineering approaches and platforms are available to more accurately replicate the in vivo 3D microarchitectures and functions of living organs. This review aims to highlight the recent 3D in vitro liver model systems, including micropatterning, spheroids, and organoids that are either scaffold-based or scaffold-free systems. Finally, we discuss a number of challenges that will need to be addressed moving forward in the field of liver tissue engineering for biomedical applications.

CONCLUSION

The ongoing development of biomedical engineering holds great promise for generating a 3D biomimetic liver model that recapitulates the physiological and pathological properties of the liver and has biomedical applications.

Hawthorn Herbal Preparation from Crataegus oxyacantha Attenuates In Vivo Carbon Tetrachloride -Induced Hepatic Fibrosis via Modulating Oxidative Stress and Inflammation

Hawthorn (HAW) is a herbal preparation extracted from Crataegus oxyacantha. HAW has cardioprotective, antioxidants, anti-inflammatory, and anti-hypotensive effects. HAW’s effect on hepatic fibrosis remains, however, unknown. This study evaluated the impact of HAW on carbon tetrachloride (CCl4)-induced hepatic fibrosis in rats and elucidated its mechanisms. HAW reduced liver index and the serum liver enzyme markers and reduced liver damage, and fibrosis as confirmed by histopathological scoring of hematoxylin-eosin staining. Collagen deposition was reduced in HAW group compared to CCl4 group as confirmed by Masson staining, hydroxyproline content, and both mRNA and protein levels of alpha-smooth muscle actin, collagen 1 and 3. HAW also down regulated the gene expressions of inflammatory markers including interleukin-IL-1β, tumor necrosis factor-α, transforming growth factor-β 1, nuclear factor kappa-B, and cyclooxygenase-2 and decreased the myeloperoxidase activity. The effects of HAW was also associated with decreased levels of hepatic oxidative stress markers (malondialdehyde and P.Carbonyl) and with increased activity of superoxide dismutase. Those effects are possibly mediated by blocking the pro-oxidant machinery and down regulating the inflammatory and profibrotic responses. Finally, chlorogenic acid, epicatechin, rutin, vitexin quercetin, and iso quercetin were identified as the major species of polyphenols of the HAW herbal preparation used here. Therefore, HAW’s potent protecting effects against liver fibrosis predicts a significant beneficial application.

Naringenin Ameliorate Carbon Tetrachloride-Induced Hepatic Damage Through Inhibition of Endoplasmic Reticulum Stress and Autophagy in Rats

Hepatic fibrosis emerges upon exposure of liver to various chemicals and if not treated, it develops various diseases such as cirrhosis and cancer. Carbon tetrachloride (CCl₄) is a widely used toxin in animal models to develop hepatic fibrosis. Accumulation of unfolded proteins in cells causes stress in the endoplasmic reticulum (ER) and various mechanisms are involved in the cell to reduce the damage caused by these unfolding proteins. The most well known of these is the unfolded protein response. Further, autophagy works to remove these proteins if the damage cannot be repaired and is permanent. In our study, we investigated the effects of naringenin (NRG), a flavanon abundant in citrus fruits, on ER stress and autophagy in CCl₄-injured rat liver. The animals were given 0.2 mL/kg of CCl₄ for 10 days and treatment group was administered 100 mg/kg of NRG for 14 days. Histopathological examination was performed to show liver damage and to determine the therapeutic properties of the active substance. Transmission electron microscopy (TEM) analysis was carried out to establish cell level damage and effect of treatment. In addition, levels of ER stress and autophagy markers of liver were measured. According to our findings, TEM demonstrated positive effect of NRG and histological examinations reported ameliorative effects. In addition, NRG reduced levels of ER stress markers and inhibited autophagy significantly compared to CCl₄-treated group. As a result, NRG significantly reduced damage in hepatocytes and provided a significant amelioration.

Therapeutic effects of AdipoRon on liver inflammation and fibrosis induced by CCl4 in mice

OBJECTIVE

The present work aimed to investigate the effects of AdipoRon against acute hepatitis and liver fibrosis induced by carbon tetrachloride (CCl₄) in mice.

METHODS

C57BL/6 mice were randomly divided into five groups: control, model, AdipoRon groups (three different dosages), CCl₄ was administered to induce acute hepatitis or liver fibrosis except for control group. The liver function, inflammatory and fibrotic profiles were evaluated by histology, immunohistochemistry and expression analysis, respectively.

RESULTS

AdipoRon pretreatment effectively attenuated oxidative stress and hepatocellular damage in acute CCl₄ intoxication, demonstrated by marked reduction in peroxidation indexes [hepatic malonaldehyde (MDA), total nitric oxide synthase (tNOS), inducible nitric oxide synthase (iNOS)] and serum transaminases [alanine aminotransferase (ALT), aspartate transaminase (AST)]. Moreover, AdipoRon attenuated the severity of fibrosis induced by sustaining CCl₄ challenge, with the alleviation of fibrous deposit and architecture distortion. The levels of canonical fibrosis markers (aminotransferases, hydroxyproline, hyaluronic acid, laminin) were also dose-dependently modulated by AdipoRon. Immunochemistry and expression analysis showed AdipoRon restrained the proinflammatory and profibrotic cytokines (TNF-α, TGF-β1, α-SMA, COL1A1), which somehow, ascribed the anti-fibrotic action to inhibiting hepatic stellate cells (HSCs) activation and quenching specific inflammation-fibrogenesis pathways.

CONCLUSIONS

AdipoRon demonstrates a remedial capacity against hepatitis and fibrosis induced by CCl₄, potentially by inflammation restraint and HSC deactivation, which might pave the way for its therapeutical application in hepatic fibrosis.

Differentiation-inducing factor-1 prevents hepatic stellate cell activation through inhibiting GSK3β inactivation

Differentiation-inducing factor-1 (DIF-1), a morphogen produced by the cellular slime mold Dictyostelium discoideum, is a natural product that has attracted considerable attention for its antitumor properties. Here, we report a novel inhibitory effect of DIF-1 on the activation of hepatic stellate cells (HSCs) responsible for liver fibrosis. DIF-1 drastically inhibited transdifferentiation of quiescent HSCs into myofibroblastic activated HSCs in a concentration-dependent manner, thus conferring an antifibrotic effect against in the liver. Neither SQ22536, an adenylate cyclase inhibitor, nor ODQ, a guanylate cyclase inhibitor, showed any effect on the inhibition of HSC activation by DIF-1. In contrast, TWS119, a glycogen synthase kinase 3β (GSK3β) inhibitor, attenuated the inhibitory effect of DIF-1. Moreover, the level of inactive GSK3β (phosphorylated at Ser9) was significantly reduced by DIF-1. DIF-1 also inhibited nuclear translocation of β-catenin and reduced the level of non-phospho (active) β-catenin. These results suggest that DIF-1 inhibits HSC activation by disrupting the Wnt/β-catenin signaling pathway through dephosphorylation of GSK3β. We propose that DIF-1 is a possible candidate as a therapeutic agent for preventing liver fibrosis.

The deficiency and the supplementation of vitamin D and liver: Lessons of chronic fructose-rich diet in mice

The fructose added to soft drinks and processed food, as well as frequent detection of vitamin D deficiency in the body, are two insults increasingly considered to cause lesions in target organs. We studied the liver after a chronic high-fructose diet deficient and supplemented with vitamin D. Sixty C57BL/6 mature male mice were allocated into six groups (n = 10) for ten weeks: control (C), control deficient in vitamin D (CDD), control supplemented with vitamin D (CDS), fructose (F), fructose deficient in vitamin D (FDD), and fructose supplemented with vitamin D (FDS). The gene expressions of vitamin D receptor and CYP27B1 and 25 hydroxyvitamin D plasma level ensured that the diets caused vitamin D deficiency or supplementation. Body mass did not change, but blood pressure (BP) increased in CDD, F, and FDD, whereas BP was controlled in FDS. Insulinemia, insulin tolerance and resistance were seen in both vitamin D deficiency and fructose groups but improved with vitamin D supplementation. The steatosis and fibrosis were observed in the CDD, F and FDD groups. Also, F and FDD showed activation of stellate cells (HSC). Lipogenesis and inflammation gene expressions were enhanced in the CDD, F and FDD groups, but diminished with vitamin D supplementation. In conclusion, we demonstrated the adverse effects of vitamin D deficiency on metabolism, liver steatosis and, combined with fructose intake, liver interstitial fibrosis with hepatic stellate cell activation, and alteration of the lipogenesis, beta-oxidation, and liver inflammation. All these data improved when vitamin D was supplemented in the animals.

Microvesicles Derived from TGF-β1 Stimulated Hepatic Stellate Cells Aggravate Hepatocellular Injury

Hepatic stellate cells (HSCs) are liver-specific cells playing critical roles in liver physiological and pathophysiological processes. Transforming growth factor-β1 (TGF-β1) is an inflammatory cytokine secreted by both hepatocytes and HSCs. We have previously shown that microvesicles (MVs) derived from quiescent HSCs protect hepatocyte functions. In this study, we investigated the effects of MVs released from TGF-β1-stimulated HSCs (HSC-MVs) on xenobiotic-injured hepatocytes. Two hepatocyte cell lines (BRL-3A and HL-7702) were treated with N-acetyl-p-aminophenol or H₂O₂ to build the injury models. Different concentrations of HSC-MVs were used to coculture with injured hepatocytes. MTT, Hochest33258 staining, and flow cytometry were used to determine their effects on the viability and apoptosis of hepatocytes. Liver injury indicators, alanine aminotransferase (ALT) and aspartate amino transferase (AST), were assessed by enzyme-linked immune sorbent assay kits. The phosphoinositide 3-kinase (PI3K) activator (740Y-P) and extracelluar signal regulated kinase (Erk)1/2 activator (platelet-derived growth factor-BB) were used for pathway analysis. The expression levels of p-PI3K/PI3K, p-Akt/Akt, and activated caspase-3 were measured by western blot. Results showed that (i) HSC-MVs dose dependently impaired the viability of hepatocytes in both injury models, (ii) moreover, HSC-MVs dose dependently increased the apoptosis in those cell models, (iii) HSC-MVs also elevated the levels of ALT and AST in the coculture media, and (iv) these effects were accompanied by a decrease in p-PI3K/PI3K and p-Akt/Akt, which could be partially abolished by 740Y-P. Meanwhile, the proapoptotic effect of HSC-MVs was associated with p-Erk1/2/Erk1/2 downregulation and activated caspase-3 upregulation, and could be inhibited by Erk1/2 activation. Our findings demonstrate that HSC-MVs are involved in inflammatory hepatocytes injury probably through the PI3K/Akt, Erk1/2, and caspase-3 pathways.

Integration of VEGF and α-SMA Expression Improves the Prediction Accuracy of Fibrosis in Chronic Hepatitis C Liver Biopsy

INTRODUCTION

The progression of fibrosis in chronic hepatitis C (CHC) is a multifactorial process. The high adverse effects and the cost of standard health care increase the demand to discover new predictors for the progression of fibrosis in CHC patients. Our study aims to establish the relation between the angiogenic marker [vascular endothelial growth factor (VEGF)] and activated hepatic stellate cells (HSCs) represented by the expression of α-smooth muscle actin (α-SMA) and whether these 2 markers can be used as predictors for the progression of fibrosis in patients with CHC.

MATERIALS AND METHODS

Histopathologic and immunohistochemical analyses were used for examining the morphology and the expression of VEGF and α-SMA in 60 CHC biopsies procured from CHC patients. Multivariate analysis was used to correlate the protein expression with staging and grading of liver fibrosis. Cutoff values of α-SMA and VEGF were determined by the receiver operating characteristics curve.

RESULTS

There was a positive correlation between VEGF and HSCs expressing α-SMA (ρ=0.287, P=0.026) and both factors were correlated with the stage of fibrosis (P<0.001). Using the receiver operating characteristics curve, both VEGF (area under the curve=0.71, P<0.006) and α-SMA (area under the curve=0.82, P<0.001) were positive predictors for moderate and severe fibrosis.

CONCLUSIONS

This study demonstrates the relation between VEGF expression and the activated HSCs denoted by the expression of α-SMA in CHC biopsies and together can be used as a predictor for the progression of fibrosis.

The anti-fibrotic role of mast cells in the liver is mediated by HLA-G and interaction with hepatic stellate cells

BACKGROUND & AIMS

We have reported a significant association between HLA-G expression or the number of hepatic mast cells and liver fibrosis. Here, we investigated the role of HLA-G and mast cells in liver fibrosis, focusing, in particular, on interactions between human mast and stellate cells.

METHODS

Human mast cells (HMC cell line, CD34-derived mast cells, or tissue-derived mast cells) were co-cultured with purified human hepatic stellate cells (HSCs), and collagen I production by HSCs was evaluated. Mast cells and HSCs were characterized by immunocytochemistry. Various conditions were tested: different times in direct or indirect contact, presence or absence of cytokines, addition or not of HLA-G, and presence or absence of specific protease inhibitors.

RESULTS

The reciprocal interaction between HSCs and mast cells led to the attraction of mast cells to HSCs in vivo and in vitro, and to a significant decrease in collagen production, at all times of co-culture, following the direct or indirect contact of mast cells with HSCs alone or in the presence of TGF-β, IFN-α or IL-10. We identified the diffusible factors involved in collagen I degradation as mast cell proteases. Moreover, HLA-G expression increased during the co-culture of HSCs and mast cells, with HLA-G acting on both mast cells and HSCs, to enhance collagen I degradation.

CONCLUSIONS

Mast cells play a beneficial, anti-fibrotic role in liver fibrosis, via the HLA-G-mediated decrease of collagen I. These findings are consistent with high levels of cross-communication between mast cells and hepatic stellate cells and the role of HLA-G.

Hepatitis C: From inflammatory pathogenesis to anti-inflammatory/hepatoprotective therapy

Hepatitis C virus (HCV) infection commonly causes progressive liver diseases that deteriorate from chronic inflammation to fibrosis, cirrhosis and even to hepatocellular carcinoma. A long-term, persistent and uncontrolled inflammatory response is a hallmark of these diseases and further leads to hepatic injury and more severe disease progression. The levels of inflammatory cytokines and chemokines change with the states of infection and treatment, and therefore, they may serve as candidate biomarkers for disease progression and therapeutic effects. The mechanisms of HCV-induced inflammation involve classic pathogen pattern recognition, inflammasome activation, intrahepatic inflammatory cascade response, and oxidative and endoplasmic reticulum stress. Direct-acting antivirals (DAAs) are the first-choice therapy for effectively eliminating HCV, but DAAs alone are not sufficient to block the uncontrolled inflammation and severe liver injury in HCV-infected individuals. Some patients who achieve a sustained virologic response after DAA therapy are still at a long-term risk for progression to liver cirrhosis and hepatocellular carcinoma. Therefore, coupling with anti-inflammatory/hepatoprotective agents with anti-HCV effects is a promising therapeutic regimen for these patients during or after treatment with DAAs. In this review, we discuss the relationship between inflammatory mediators and HCV infection, summarize the mechanisms of HCV-induced inflammation, and describe the potential roles of anti-inflammatory/hepatoprotective drugs with anti-HCV activity in the treatment of advanced HCV infection.

Mechanism of combined use of vitamin D and puerarin in anti-hepatic fibrosis by regulating the Wnt/β-catenin signalling pathway

AIM

To reveal the protective mechanism of the combined use of vitamin D and puerarin in the progression of hepatic fibrosis induced by carbon tetrachloride (CCl₄).

METHODS

Eight-week-old male Wistar rats were randomly divided into a normal control group (C group), a CCl₄ group (CCl₄ group), a vitamin D group (V group), a puerarin group (P group), and a combined group of vitamin D and puerarin (V + P group), each of which contained ten rats. In this way, we built a rat model of CCl₄-induced hepatic fibrosis with intervention by vitamin D, puerarin, or a combination of the two. After eight weeks, the mice were sacrificed to collect serum and liver specimens. Blood was collected to detect the hyaluronic acid (HA). We also measured hydroxyproline (Hyp) and prepared paraffin sections of liver. After Sirius red staining, the liver specimens were observed under a microscope. RT-PCR and western blot analysis were adopted to detect the mRNA and the protein levels of Collagen I, Collagen III, Wnt1, and β-catenin in the liver tissues, respectively.

RESULTS

Hepatic fibrosis was observed in the CCl₄ group. In comparison, hepatic fibrosis was attenuated in the V, P, and V + P groups: the HA level in blood and the Hyp level in liver were reduced, and the mRNA levels of Collagen I, Collagen III, Wnt, and β-catenin in liver were also decreased, as well as the protein levels of Wnt1 and β-catenin. Among these groups, the V + P group demonstrated the greatest amelioration of hepatic fibrosis.

CONCLUSION

The combined application of vitamin D and puerarin is capable of alleviating CCl₄-induced hepatic fibrosis of rats. As to the mechanism, it is probably because the combined use is able to silence the Wnt1/β-catenin pathway, suppress the activation of hepatic stellate cells, and reduce the secretion of collagen fibers, therefore improving the anti-hepatic fibrosis effect.

The contributions of mesoderm-derived cells in liver development

The liver is an indispensable organ for metabolism and drug detoxification. The liver consists of endoderm-derived hepatobiliary lineages and various mesoderm-derived cells, and interacts with the surrounding tissues and organs through the ventral mesentery. Liver development, from hepatic specification to liver maturation, requires close interactions with mesoderm-derived cells, such as mesothelial cells, hepatic stellate cells, mesenchymal cells, liver sinusoidal endothelial cells and hematopoietic cells. These cells affect liver development through precise signaling events and even direct physical contact. Through the use of new techniques, emerging studies have recently led to a deeper understanding of liver development and its related mechanisms, especially the roles of mesodermal cells in liver development. Based on these developments, the current protocols for in vitro hepatocyte-like cell induction and liver-like tissue construction have been optimized and are of great importance for the treatment of liver diseases. Here, we review the roles of mesoderm-derived cells in the processes of liver development, hepatocyte-like cell induction and liver-like tissue construction.

Major Changes of von Willebrand Factor Multimer Distribution in Cirrhotic Patients with Stable Disease or Acute Decompensation

Background  There is an unstable balance between pro- and anti-haemostatic processes in patients with cirrhosis. We hypothesized, that in patients with acute decompensation (AD) the major alterations of von Willebrand factor (VWF) could contribute to the pro-thrombotic situation as compared to patients with stable (ST) cirrhosis.

Patients and Methods  We analysed different parameters of VWF, including detailed multimer distribution by densitometry and platelet adhesion, together with ad isintegrin-like a nd m etalloproteinase with t hrombo s pondin type-1 motifs 13 (ADAMTS13) activity and antigen and C-reactive protein (CRP) levels in patients with ST cirrhosis ( n  = 99), with AD ( n  = 54) and controls ( n  = 92).

Results  VWF antigen, ristocetin co-factor as well as collagen-binding activities were elevated in both cirrhotic groups in a stepwise manner. There was a decrease in high and an increase in low molecular weight multimer ratios in the majority of ST cirrhosis. However, in 24 out of 54 AD patients, ultra-large VWF multimers (ultra-large molecular weight multimers [ULMWM]) were found. ADAMTS13 activity in ST and AD patients without ULMWM was similar to controls (median [interquartile range; IQR]%: 98 [67–132] and 91 [60–110] vs. 106 [88–117], respectively). The presence of ULMWM in AD patients was associated with low ADAMTS13 activity [33 (24–49)%] and high CRP level [23 (7.1–83.6) mg/L]. Adhesion of normal platelets showed a stepwise increase in the presence of cirrhotic plasmas, reaching the highest level in AD patients with ULMWM.

Conclusion  Characteristic changes of VWF parameters are seen in ST cirrhosis. In AD patients, highly increased VWF and reduced ADAMTS13 activity could be found, along with the presence of ULMWM, which are possible markers and contributors of the disease progression.

Protective effect of ethyl acetate fraction of Drynaria quercifolia against CCl4 induced rat liver fibrosis via Nrf2/ARE and NFκB signalling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Drynaria quercifolia rhizome is traditionally used as hepatoprotective drug especially in chronic jaundice.

AIM OF THE STUDY

The present study was undertaken to scientifically evaluate the efficacy of D. quercifolia rhizome against liver fibrosis.

MATERIALS AND METHODS

D. quercifolia rhizome crude extract (DQ) and its fractions of hexane (HDQ), ethyl acetate (EDQ), butanol (BDQ) were evaluated in vitro using primary hepatocytes and RAW 264.7 cells. In vivo anti-liver fibrotic activity of EDQ was assessed using CCl₄ induced liver fibrosis in Wistar rats and serum biochemical parameters (AST, ALT, ALP, SB, cholesterol), MDA, PT, INR, GSH, SOD, CAT, liver glycogen, serum albumin levels were monitored. qRT-PCR analysis of TNF-α, COX-2, iNOS were performed. ELISA method was used to estimate TNF-α, COX-1 & 2. Histopathological studies like H & E, Masson's trichrome, immunohistochemistry staining for α-SMA, TIMP-1, Nrf2 were conducted. LC-Q-TOF-MS analysis of EDQ was conducted.

RESULTS

In vitro activity guided fractionation of D. quercifolia revealed EDQ as active fraction when compared to other extracts. EDQ treatment significantly inhibited the expression of α-SMA, TIMP-1, COX-2, TNF-α, iNOS and increased the levels of Nrf2 in rat liver fibrosis. LC-Q-TOF-MS analysis of EDQ confirmed the presence of naringin and naringenin.

CONCLUSION

The anti-liver fibrotic activity of EDQ is via inhibition of NFκB signalling pathway, antioxidant response through Nrf2 activation and further inhibition of HSC activation.

Caffeine Suppresses the Activation of Hepatic Stellate Cells cAMP-Independently by Antagonizing Adenosine Receptors

During liver injury, hepatic stellate cells (HSCs) are activated by various cytokines and transdifferentiated into myofibroblast-like activated HSCs, which produce collagen, a major source of liver fibrosis. Therefore, the suppression of HSC activation is regarded as a therapeutic target for liver fibrosis. Several epidemiological reports have revealed that caffeine intake decreases the risk of liver disease. In this study, therefore, we investigated the effect of caffeine on the activation of primary HSCs isolated from mice. Caffeine suppressed the activation of HSC in a concentration-dependent manner. BAPTA-AM, an intracellular Ca²⁺ chelator, had no effect on the caffeine-induced suppression of HSC activation. None of the isoform-selective inhibitors of phosphodiesterase1 to 5 affected changes in the morphology of HSC during activation, whereas CGS-15943, an adenosine receptor antagonist, inhibited them. Caffeine had no effect on intracellular cAMP level or on the phosphorylation of extracellular signal-regulated kinase (ERK)1/2. In contrast, caffeine significantly decreased the phosphorylation of Akt1. These results suggest that caffeine inhibits HSC activation by antagonizing adenosine receptors, leading to Akt1 signaling activation.

Melatonin mitigates thioacetamide-induced hepatic fibrosis via antioxidant activity and modulation of proinflammatory cytokines and fibrogenic genes

AIMS

The potential antifibrotic effects of melatonin against induced hepatic fibrosis were explored.

MAIN METHODS

Rats were allocated into four groups: placebo; thioacetamide (TAA) (200mg/kg bwt, i.p twice weekly for two months); melatonin (5mg/kgbwt, i.p daily for a week before TAA and continued for an additional two months); and melatonin plus TAA. Hepatic fibrotic changes were evaluated biochemically and histopathologically. Hepatic oxidative/antioxidative indices were assessed. The expression of hepatic proinflammatory cytokines (tumor necrosis factor-α, and interleukin-1β), fibrogenic-related genes (transforming growth factor-1β, collagen I, collagen, III, laminin, and autotaxin) and an antioxidant-related gene (thioredoxin-1) were detected by qRT-PCR.

KEY FINDINGS

In fibrotic rats, melatonin lowered serum aspartate aminotransferase, alanine aminotransferase, and autotaxin activities, bilirubin, hepatic hydroxyproline and plasma ammonia levels. Melatonin displayed hepatoprotective and antifibrotic potential as indicated by mild hydropic degeneration of some hepatocytes and mild fibroplasia. In addition, TAA induced the depletion of glutathione, glutathione s-transferase, glutathione peroxidase, superoxide dismutase, catalase, and paraoxonase-1 (PON-1), while inducing the accumulation of malondialdehyde, protein carbonyl (C=O) and nitric oxide (NO), and DNA fragmentation. These effects were restored by melatonin pretreatment. Furthermore, melatonin markedly attenuated the expression of proinflammatory cytokines and fibrogenic genes via the upregulation of thioredoxin-1 mRNA transcripts.

SIGNIFICANCE

Melatonin exhibits potent anti-inflammatory, antioxidant and fibrosuppressive activities against TAA-induced hepatic fibrogenesis via the suppression of oxidative stress, DNA damage, proinflammatory cytokines and fibrogenic gene transcripts. In addition, we demonstrate that the antifibrotic activity of melatonin is mediated by the induction of thioredoxin-1 with attenuation of autotaxin expressions.

A three-dimensional cell culture device for simulation of hepatic hypertension

Hepatic stellate cells (HSCs) play a crucial role in the development of liver fibrosis which is characterized by massive tissue scarring, elevated hepatic sinusoidal pressure, and portal hypertension. However, while a multitude of chemical factors have been investigated in the pathogenesis of liver fibrosis, physical factors such as elevated hydrostatic pressure and shear stress caused by blood flow in sinusoids remain unclear. In this study, we developed a three-dimensional (3D) cell culture microfluidic platform that mimics the physical environments of hepatic sinusoids to investigate the effects of elevated hydrostatic pressure on HSCs phenotypes.

Effects and mechanism of adenovirus-mediated phosphatase and tension homologue deleted on chromosome ten gene on collagen deposition in rat liver fibrosis

AIM

To evaluate the effects of phosphatase and tension homologue deleted on chromosome ten (PTEN) gene on collagen metabolism in hepatic fibrosis and the underlying mechanisms.

METHODS

Rat primary hepatic stellate cells (HSCs) and human LX-2 cells were transfected with adenovirus containing cDNA constructs encoding wild-type PTEN (Ad-PTEN), PTEN mutant G129E gene (Ad-G129E), and RNA interference constructs targeting the PTEN sequence PTEN short hairpin RNA to up-regulate and down-regulate the expression of PTEN. HSCs were assayed using fluorescent microscopy, real-time polymerase chain reaction, and western blotting. Moreover, a CCl₄-induced rat hepatic fibrosis model was established to investigate the in vivo effects. Hematoxylin and eosin, and Masson’s trichrome were used to assess the histological changes. The expression of collagen I and III was assessed using immunohistochemistry and western blot analysis.

RESULTS

Elevated expression of PTEN gene reduced serum levels of alanine transaminase and aspartate transaminase, decreased collagen deposition in the liver, and reduced hepatocyte necrosis. In contrast, knockdown of PTEN expression had an opposite effect, such as increased collagen deposition in the liver, and was molecularly characterized by the increased expression of matrix metalloproteinase (MMP)-13 (P < 0.01) and MMP-2 (P < 0.01), as well as decreased expression of the tissue inhibitor of metalloproteinase (TIMP)-1 (P < 0.01) and TIMP-2 (P < 0.01).

CONCLUSION

These data indicated that gene therapy using recombinant adenovirus encoding PTEN might be a novel way of treating hepatic fibrosis.

Regulation of hepatic stellate cell proliferation and activation by glutamine metabolism

Liver fibrosis is the excessive accumulation of extracellular matrix proteins, which is mainly caused by accumulation of activated hepatic stellate cells (HSCs). The mechanisms of activation and proliferation of HSCs, two key events after liver damage, have been studied for many years. Here we report a novel pathway to control HSCs by regulating glutamine metabolism. We demonstrated that the proliferation of HSCs is critically dependent on glutamine that is used to generate α-ketoglutarate (α-KG) and non-essential amino acid (NEAA). In addition, both culture- and in vivo-activated HSCs have increased glutamine utilization and increased expression of genes related to glutamine metabolism, including GLS (glutaminase), aspartate transaminase (GOT1) and glutamate dehydrogenase (GLUD1). Inhibition of these enzymes, as well as glutamine depletion, had a significant inhibitory effect on HSCs activation. In addition to providing energy expenditure, conversion of glutamine to proline is enhanced. The pool of free proline may also be increased via downregulation of POX expression. Hedgehog signaling plays an important role in the regulation of glutamine metabolism, as well as TGF-β1, c-Myc, and Ras signalings, via transcriptional upregulation and repression of key metabolic enzymes in this pathway. Finally, changes in glutamine metabolism were also found in mouse liver tissue following CCl4-induced acute injury.

CONCLUSION

Glutamine metabolism plays an important role in regulating the proliferation and activation of HSCs. Strategies that are targeted at glutamine metabolism may represent a novel therapeutic approach to the treatment of liver fibrosis.

Effects of lentiviral vector‑mediated shRNA silencing of TGFβ1 on the expression of Col1a1 in rat hepatic stellate cells

The present study aimed to construct a lentiviral RNA interference (RNAi) vector targeting the transforming growth factor β1 (TGFβ1) gene of rats, in order to examine its effect on silencing of the TGFβ1 gene and on the expression of collagen type 1 α1 (Col1a1) in HSC‑T6 rat hepatic stellate cells. Three RNAi sites of the TGFβ1 gene were selected according to its CDs sequence. Three pairs of small interfering RNA (siRNA) of these RNAi sites were synthesized and then transfected into HSC‑T6 cells, respectively, to confirm the optimal siRNA sequence via reverse transcription‑polymerase chain reaction analysis. Subsequently, shRNA targeting the sequence of the optimal siRNA was designed, synthesized and annealed to form a double‑stranded structure. The annealed oligonucleotide fragment was cloned into pGreenPuro plasmids to establish the pGreenPuro/TGFβ1 shRNA lentiviral vector, which was then transfected into 293T cells, following identification by restriction enzyme digestion and sequencing for the production of lentiviral particles exhibiting high reactivity. These particles were used to infect HSC‑T6 cells, following which the expression of GFP in the transfected cells was observed under an inverted microscope. The effects on TGFβ1 gene silencing and the expression levels of Colla1 were detected at the mRNA and protein levels. The results provided confirmation of the optimal siRNA sequence. Enzyme digestion and sequencing verified successful construction of the pGreenPuro/TGFβ1 shRNA lentiviral vector. This lentiviral vector effectively silenced the TGFβ1 gene in the HSC‑T6 cells, and inhibited the expression of Col1a1 at the mRNA and protein levels. Taken together, the lentiviral RNAi vector targeting the TGFβ1 gene of rats was successfully constructed, which effectively silenced the TGFβ1 gene of the HSC‑T6 cells and inhibited the expression of Col1a1.

Rosmarinic acid attenuates hepatic fibrogenesis via suppression of hepatic stellate cell activation/proliferation and induction of apoptosis

OBJECTIVE

To investigate the antifibrotic role of rosmarinic acid (RA), a natural polyphenolic compound, on HSCs activation/proliferation and apoptosis in vitro and in vivo.

METHODS

The impact of RA on stellate cell line (HSC-T6) proliferation, activation and apoptosis was assessed along with its safety on primary hepatocytes. In vivo, rats were divided into: (i) normal; (ii) thioacetamide (TAA)-intoxicated rats for 12 weeks; (iii) TAA + silymarin or (iv) TAA + RA. At the end of experiment, liver functions, oxidative stress, inflammatory and profibrogenic markers, tissue inhibitor metalloproteinases type-1 (TIMP-1) and hydroxyproline (HP) levels were evaluated. Additionally, liver histopathology and immunohistochemical examinations of alpha-smooth muscle actin (α-SMA), caspase-3 and proliferation cellular nuclear antigen (PCNA) were determined.

RESULTS

RA exhibited anti-proliferative effects on cultured HSCs in a time and concentration dependent manner showing an IC₅₀ of 276 μg/mL and 171 μg/mL for 24 h and 48 h, respectively, with morphological reversion of activated stellate cell morphology to quiescent form. It significantly improved ALT, AST, oxidative stress markers and reduced TIMP-1, HP levels, inflammatory markers and fibrosis score (S1 vs S4). Furthermore, reduction in α-SMA plus elevation in caspase-3 expressions of HSCs in vitro and in vivo associated with an inhibition in proliferation of damaged hepatocytes were recorded.

CONCLUSIONS

RA impeded the progression of liver fibrosis through inhibition of HSCs activation/proliferation and induction of apoptosis with preservation of hepatic architecture.

Quantitative Measurement of Hepatic Fibrosis with Gadoxetic Acid-Enhanced Magnetic Resonance Imaging in Patients with Chronic Hepatitis B Infection: A Comparative Study on Aspartate Aminotransferase to Platelet Ratio Index and Fibrosis-4 Index

Objective

To quantitatively measure hepatic fibrosis on gadoxetic acid-enhanced magnetic resonance (MR) in chronic hepatitis B (CHB) patients and identify the correlations with aspartate aminotransferase-to-platelet ratio index (APRI) and fibrosis-4 index (FIB-4) values.

Materials and Methods

This study on gadoxetic acid-enhanced 3T MR imaging included 81 patients with CHB infection. To quantitatively measure hepatic fibrosis, MR images were analyzed with an aim to identify inhomogeneous signal intensities calculated from a coefficient of variation (CV) map in the liver parenchyma. We also carried out a comparative analysis between APRI and FIB-4 based on metaregression results. The diagnostic performance of the CV map was evaluated using a receiver-operating characteristic (ROC) curve.

Results

In the MR images, the mean CV values in control, groups I, II, and III based on APRI were 4.08 ± 0.92, 4.24 ± 0.80, 5.64 ± 1.11, and 5.73 ± 1.28, respectively (p < 0.001). In CHB patients grouped by FIB-4, the mean CV values of groups A, B, and C were 4.22 ± 0.95, 5.40 ± 1.19, and 5.71 ± 1.17, respectively (p < 0.001). The mean CV values correlated well with APRI (r = 0.392, p < 0.001) and FIB-4 (r = 0.294, p < 0.001). In significant fibrosis group, ROC curve analysis yielded an area under the curve of 0.875 using APRI and 0.831 using FIB-4 in HB, respectively.

Conclusion

Gadoxetic acid-enhanced MR imaging for calculating a CV map showed moderate correlation with APRI and FIB-4 values and could be employed to quantitatively measure hepatic fibrosis in patients with CHB.

Low concentrations of bilirubin inhibit activation of hepatic stellate cells in vitro

Hepatic stellate cell (HSC) activation serves a key role in liver fibrosis, and is associated with chronic liver diseases. Bilirubin, a product of heme degradation, has been demonstrated to have antioxidant properties. The present study investigated the effects of physiological concentrations of bilirubin on rat HSC activation. Rat HSCs were isolated and cultured for several generations to induce activation. The activated HSCs were subsequently treated with 0, 1, 10 or 20 mg/l bilirubin and assayed for parameters of cell activation. As the bilirubin concentration increased, HSCs demonstrated reduced production of reactive oxygen species, reduced protein expression levels of α-smooth muscle actin, a decreased mRNA expression ratio of tissue inhibitor of matrix metalloproteinase-1/matrix metalloproteinase-2, decreased proliferation and increased apoptosis. In conclusion, elevated bilirubin levels, within its physiological concentration range, appeared to inhibit HSC activation. These findings suggested a potential role for bilirubin in the treatment of fibrosis that requires further investigation.

Circulating ECV-Associated miRNAs as Potential Clinical Biomarkers in Early Stage HBV and HCV Induced Liver Fibrosis

Introduction: Chronic hepatitis B (HBV) and C (HCV) virus infection is associated with the activation of hepatic stellate cells (HSCs) toward a myofibroblastic phenotype, resulting in excessive deposition of extracellular matrix, the development of liver fibrosis, and its progression toward cirrhosis. The gold standard for the detection and staging of liver fibrosis remains the liver biopsy, which is, however, associated with some mild and severe drawbacks. Other non-invasive techniques evade these drawbacks, but lack inter-stage specificity and are unable to detect early stages of fibrosis. We investigated whether circulating vesicle-associated miRNAs can be used in the diagnosis and staging of liver fibrosis in HBV and HCV patients.

Methods: Plasma samples were obtained from 14 healthy individuals and 39 early stage fibrotic patients (F0–F2) with chronic HBV or HCV infection who underwent transient elastography (Fibroscan). Extracellular vesicles were extracted from the plasma and the level of miRNA-122, -150, -192, -21, -200b, and -92a was analyzed by qRT-PCR in total plasma and circulating vesicles. Finally, these same miRNAs were also quantified in vesicles extracted from in vitro activating primary HSCs.

Results: In total plasma samples, only miRNA-200b (HBV: p = 0.0384; HCV: p = 0.0069) and miRNA-122 (HBV: p < 0.0001; HCV: p = 0.0007) were significantly up-regulated during early fibrosis. In circulating vesicles, miRNA-192 (HBV: p < 0.0001; HCV: p < 0.0001), -200b (HBV: p < 0.0001; HCV: p < 0.0001), -92a (HBV: p < 0.0001; HCV: p < 0.0001), and -150 (HBV: p = 0.0016; HCV: p = 0.004) displayed a significant down-regulation in both HBV and HCV patients. MiRNA expression profiles in vesicles isolated from in vitro activating primary mouse HSCs resembled the miRNA expression profile in circulating vesicles.

Conclusion: Our analysis revealed a distinct miRNA expression pattern in total plasma and its circulating vesicles. The expression profile of miRNAs in circulating vesicles of fibrotic patients suggests the potential use of these vesicle-associated miRNAs as markers for early stages of liver fibrosis.

Prolyl oligopeptidase attenuates hepatic stellate cell activation through induction of Smad7 and PPAR-γ

Prolyl oligopeptidase (POP) is a serine endopeptidase widely distributed in vivo with high activity in the liver. However, its biological functions in the liver have remained largely elusive. A previous study by our group has shown that POP produced N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) and thereby exerted an anti-fibrogenic effect on hepatic stellate cells (HSCs) in vitro. It was therefore hypothesized that POP may affect the activation state of HSCs and has an important role in liver fibrosis. The HSC-T6 immortalized rat liver stellate cell line was treated with the POP inhibitor S17092 or transfected with recombinant lentivirus to overexpress POP. Cell proliferation and apoptosis were determined using a Cell Counting Kit-8 and flow cytometry, respectively. The activation status of HSCs was determined by examination of the expression of α-smooth muscle actin (α-SMA), collagen I, monocyte chemoattractant protein-1 (MCP-1), transforming growth factor (TGF)-β-Smad signaling and peroxisome proliferator activated receptor-γ (PPAR-γ). Inhibition by S17092 decreased, whereas lentiviral expression increased the activity of POP and cell proliferation, while neither of the treatments affected cell apoptosis. Of note, S17092 significantly increased, whereas POP overexpression decreased the expression of α-SMA and MCP-1 without affecting the expression of collagen I and TGF-β1. Furthermore, S17092 caused a reduction, whereas POP overexpression caused an upregulation of Smad7 protein and PPAR-γ, but not phosphorylated-Smad2/3 expression. In conclusion, POP attenuated the activation of HSCs through inhibition of TGF-β signaling and induction of PPAR-γ, which may have therapeutic potential in liver fibrosis.

A 3D alcoholic liver disease model on a chip

Alcohol is one of the main causes of liver diseases, and the development of alcoholic liver disease (ALD) treatment methods has been one of the hottest issues. For this purpose, development of in vitro models mimicking the in vivo physiology is one of the critical requirements, and they help to determine the disease mechanisms and to discover the treatment method. Herein, a three-dimensional (3D) ALD model was developed and its superior features in mimicking the in vivo condition were demonstrated. A spheroid-based microfluidic chip was employed for the development of the 3D in vitro model of ALD progression. We co-cultured rat primary hepatocytes and hepatic stellate cells (HSCs) in a fluidic chip to investigate the role of HSCs in the recovery of liver with ALD. An interstitial level of flow derived by an osmotic pump was applied to the chip to provide in vivo mimicking of fluid activity. Using this in vitro tool, we were able to observe structural changes and decreased hepatic functions with the increase in ethanol concentration. The recovery process of liver injured by alcohol was observed by providing fresh culture medium to the damaged 3D liver tissue for few days. A reversibly- and irreversibly-injured ALD model was established. The proposed model can not only be used for the research of alcoholic disease mechanism, but also has the potential for use in studies of hepatotoxicity and drug screening applications.

Autophagy induced by purple pitanga (Eugenia uniflora L.) extract triggered a cooperative effect on inducing the hepatic stellate cell death

Activated hepatic stellate cells (HSC) are the major source of collagen I in liver fibrosis. Eugenia uniflora L. is a tree species that is widely distributed in South America. E. uniflora L. fruit-popularly known as pitanga-has been shown to exert beneficial properties. Autophagy contributes to the maintenance of cellular homeostasis and survival under stress situation, but it has also been suggested to be an alternative cell death pathway. Mitochondria play a pivotal role on signaling cell death. Mitophagy of damaged mitochondria is an important cell defense mechanism against organelle-mediated cell death signaling. We previously found that purple pitanga extract induced mitochondrial dysfunction, cell cycle arrest, and death by apoptosis and necrosis in GRX cells, a well-established activated HSC line. We evaluated the effects of 72-h treatment with crescent concentrations of purple pitanga extract (5 to 100 μg/mL) on triggering autophagy in GRX cells, as this is an important mechanism to cells under cytotoxic conditions. We found that all treated cells presented an increase in the mRNA expression of autophagy-related protein 7 (ATG7). Concomitantly, flow cytometry and ultrastructural analysis of treated cells revealed an increase of autophagosomes/autolysosomes that consequentially led to an increased mitophagy. As purple pitanga extract was previously found to be broadly cytotoxic to GRX cells, we postulated that autophagy contributes to this scenario, where cell death seems to be an inevitable fate. Altogether, the effectiveness on inducing activated HSC death can make purple pitanga extract a good candidate on treating liver fibrosis.

Effects of recombinant human adenovirus-p53 on the regression of hepatic fibrosis

Hepatic fibrosis is a scarring process that may progress to hepatic cirrhosis and even hepatic carcinoma if left untreated. Hepatic stellate cells (HSCs) play essential roles in the development of hepatic fibrosis. The tumor suppressor protein p53 is a transcription factor that is involved in cell proliferation, cell cycle regulation, apoptosis and DNA repair. Recombinant human adenovirus-p53 (Ad-p53) has been demonstrated to act as a promising antitumor gene therapy in various types of cancer. However, there is limited infomration regarding the therapeutic effect of Ad-p53 on the regression of hepatic fibrosis. In order to examine the underlying molecular mechanism responsible for the effects of Ad-p53 on HSCs, a rat model of hepatic fibrosis was established and HSC-T₆ cells were cultured under different conditions. The expression of p53, transforming growth factor (TGF-β1) and α-smooth muscle actin (α-SMA), which is a marker of activated HSCs, was detected by immunohistochemical assays and RT-qPCR. In vitro, five different concentrations (1×10⁶, 5×10⁶, 1×10⁷, 2×10⁷ and 5×10⁷ PFU/ml) of Ad-p53 were selected for use in the MTT assay to analyze the proliferation of HSCs at 0, 24, 48 and 72 h. Flow cytometric analysis was applied to determine the effect of three different concentrations of Ad-p53 (5×10⁶, 1×10⁷ and 2×10⁷ PFU/ml) on the cell cycle and the apoptosis of HSC-T₆ cells at 24 and 48 h. The results of immunohistochemical studies and RT-qPCR showed that Ad-p53 upregulated the expression of p53, and downregulated the expression of TGF-β1 and α-SMA. The MTT assay revealed that when treated with various doses of Ad-p53, the proliferation of HSCs was inhibited within a certain range of concentrations and time periods. Analysis of flow cytometric data showed that Ad-p53 arrested the cell cycle in G1 phase and significantly induced apoptosis. Taken together, these findings suggest that Ad-p53 promotes apoptosis and inhibits the proliferation of HSCs in a time- and dose-dependent manner by modulating the expression of p53, TGF-β1 and α-SMA.

Mesenchymal stem cell therapy for cirrhosis: Present and future perspectives

Cirrhosis occurs as a result of various chronic liver injuries, which may be caused by viral infections, alcohol abuse and the administration of drugs and chemicals. Recently, bone marrow cells (BMCs), hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs) have been used for developing treatments for cirrhosis. Clinical trials have investigated the therapeutic potential of BMCs, HSCs and MSCs for the treatment of cirrhosis based on their potential to differentiate into hepatocytes. Although the therapeutic mechanisms of BMC, HSC and MSC treatments are still not fully characterized, the evidence thus far has indicated that the potential therapeutic mechanisms of MSCs are clearer than those of BMCs or HSCs with respect to liver regenerative medicine. MSCs suppress inflammatory responses, reduce hepatocyte apoptosis, increase hepatocyte regeneration, reverse liver fibrosis and enhance liver functionality. This paper summarizes the clinical studies that have used BMCs, HSCs and MSCs in patients with liver failure or cirrhosis. We also present the potential therapeutic mechanisms of BMCs, HSCs and MSCs for the improvement of liver function.

Study on the Antifibrotic Effects of Recombinant Shark Hepatical Stimulator Analogue (r-sHSA) in Vitro and in Vivo

Hepatic fibrosis is an effusive wound healing process, characterized by an excessive deposition of extracellular matrix (ECM), as the consequence of chronic liver injury of any etiology. Current therapeutic repertoire for hepatic fibrosis is limited to withdrawal of the noxious agent, which is not always feasible. Hence, in this article, the antifibrotic effects and possible mechanisms of r-sHSA, a recombinant protein with hepatoprotection potential, were investigated. Using NIH/3T3 (mouse embro-fibroblast cell line), skin fibroblasts (human skin fibroblasts, SFBs) and HSC-T6 (rat hepatic stellate cell line), the in vitro effect of r-sHSA was evaluated by measuring the expression levels of alpha-1 Type I collagen (Col1A1) and α-smooth muscle actin (α-SMA). It turned out those fibrosis indicators were typically inhibited by r-sHSA, suggesting its capacity in HSCs inactivation. The antifibrotic activity of r-sHSA was further investigated in vivo on CCl4-induced hepatic fibrosis, in view of significant improvement of the biochemical and histological indicators. More specifically, CCl4-intoxication induced a significant increase in serological biomarkers, e.g., transaminase (AST, ALT), and alkaline phosphatase (ALP), as well as disturbed hepatic antioxidative status; most of the parameters were spontaneously ameliorated to a large extent by withdrawal of CCl4, although the fibrotic lesion was observed histologically. In contrast, r-sHSA treatment markedly eliminated fibrous deposits and restored architecture of the liver in a dose dependent manner, concomitantly with the phenomena of inflammation relief and HSCs deactivation. To sum up, these findings suggest a therapeutic potential for r-sHSA in hepatic fibrosis, though further studies are required.

Nicotinic acid prevents experimental liver fibrosis by attenuating the prooxidant process

Liver fibrosis is the excessive accumulation of extracellular matrix proteins that occurs in most chronic liver diseases. Nicotinamide treatment has been shown to prevent collagen accumulation and fibrogenesis in a bleomycin model of lung fibrosis. In this study, we evaluated the effects of nicotinic acid (NA) on experimental liver fibrosis and investigated its underlying mechanism.

METHODS

Fibrosis was induced by chronic TAA administration and the effects of co-administration with NA for 8 weeks were evaluated, including control groups.

RESULTS

TAA administration induced liver fibrosis, which was prevented by nicotinic acid. NA prevented the elevation of liver enzymes and prevented hepatic glycogen depletion. Liver histopathology and hydroxyproline levels were significantly lower in the rats treated with TAA plus NA compared with TAA only. NA demonstrated antioxidant properties by restoring the redox equilibrium (lipid peroxidation and GPx levels). Western blot assays showed decreased expression levels of TGF-β and its downstream inductor CTGF. Additionally, NA prevented hepatic stellate cell activation due by blocking the expression of α-SMA. Zymography assays showed that NA decreased the activity of matrix metalloproteinases 2 and 9.

CONCLUSIONS

NA prevents experimental fibrosis; the mechanisms of action are associated with its antioxidant properties and the reduction in TGF-β expression. The decrease in TGF-β levels may be associated with the attenuation of the oxidative processes, thus resulting in a reduction in HSC activation and ECM deposition. The findings suggest a possible role for NA as an antifibrotic agent for liver injury.

Perspectives of TGF-β inhibition in pancreatic and hepatocellular carcinomas

Advanced pancreatic ductal adenocarcinoma (PDAC) and hepatocellular carcinoma (HCC) are non-curable diseases with a particularly poor prognosis. Over the last decade, research has increasingly focused on the microenvironment surrounding cancer cells, and its role in tumour development and progression. PDAC and HCC differ markedly regarding their pathological features: PDAC are typically stromal-predominant, desmoplastic, poorly vascularized tumours, whereas HCC are cellular and highly vascularized. Despite these very different settings, PDAC and HCC share transforming growth factor-β (TGF-β) as a common key-signalling mediator, involved in epithelial-to-mesenchymal transition, invasion, and stroma-tumour dialogue. Recently, novel drugs blocking the TGF-β pathway have entered clinical evaluation demonstrating activity in patients with advanced PDAC and HCC. TGF-β signalling is complex and mediates both pro- and anti-tumoural activities in cancer cells depending on their context, in space and time, and their microenvironment. In this review we provide a comprehensive overview of the role of the TGF-β pathway and its deregulation in PDAC and HCC development and progression at the cellular and microenvironment levels. We also summarize key preclinical and clinical data on the role of TGF-β as a target for therapeutic intervention in PDAC and HCC, and explore perspectives to optimize TGF-β inhibition therapy.