Liver Injury and the Activation of the Hepatic Myofibroblasts

Enhanced stem cell-mediated therapeutic immune modulation with zinc oxide nanoparticles in liver regenerative therapy

Liver regenerative therapy is critical for severe liver damage, including acute liver failure, fibrosis, post-cancer resection recovery, and autoimmune liver diseases, where restoration of liver tissues is essential. Stem cell-based therapies hold significant promise in liver regeneration by modulating immune responses to create a favorable healing microenvironment. However, their clinical efficacy has been limited by challenges such as poor cell engraftment and survival within the hostile injury site. To address these limitations, we developed a zinc oxide-derived nanoparticle (PZnONP) that enhances stem cell proliferation and activation by releasing bioactive Zn2+ and reactive oxygen species (ROS). Functionalized PZnONP exhibits pH-responsive behavior and improved dispersibility, enabling a lysosome-specific and sustained release of Zn2+ and ROS. Stem cells labeled with PZnONP (ZnBA) demonstrated anti-inflammatory properties, with paracrine effects influencing macrophages and damaged hepatocytes. In murine models of acute and fibrotic liver injury, it effectively migrated to the liver through stem cell homing effects and promoted anti-inflammatory responses by modulating Treg and Th17 cell polarization, as well as M2 and M1 macrophage balance, while reducing collagen synthesis. This study underscores the potential of integrating stem cell-based therapy with nanomedicine to improve regenerative outcomes in liver disease treatment.

Tissue-Microenvironment-Responsive Self-Assembling Peptide Nanoshells Boost Pirfenidone Efficacy in the Treatment of Liver Fibrosis

Chronic liver disease culminates in liver fibrosis, responsible for substantial worldwide morbidity and mortality. Traditional chemical drugs that have proven effective at treating other types of tissue fibrosis may be repurposed for treating liver fibrosis but face inefficient outcomes or elicit undesirable side effects. Hepatic-targeted drug nanocarriers offer a potential strategy for achieving localized drug release to effectively alleviate liver fibrosis while mitigating off-target effects. Elevated levels of fibroblast activation protein-α (FAP-α) have been associated with liver fibrosis and the presence of platelet-derived growth-factor-receptor-β-overexpressing activated hepatic stellate cells. Therefore, FAP-α-responsive nanoshells are developed from hepatic fibrosis targeting peptides to protect and transport pirfenidone (PFD) to fibrotic livers for potentiated therapeutic efficacy. In vitro experiments validate that PFD-loaded hepatic- and fibrosis-targeting nanoshells (PFD@ns) lessen transforming-growth-factor-β1-driven collagen production and activation of hepatic stellate cells. In animal models of liver fibrosis, PFD@ns increase the efficacy of PFD in preventing fibrosis, alleviating proinflammatory cell infiltration, and modulating the PI3K/AKT/mTOR signaling pathway. In conclusion, these findings suggest that the hepatic- and fibrosis-targeted PFD@ns can potentially serve as an effective tool in the treatment of liver fibrosis.

In vivo transplantation of intrahepatic cholangiocyte organoids with decellularized liver-derived hydrogels supports hepatic cellular proliferation and differentiation in chronic liver injury

The limited replicative potential of primary hepatocytes (Hep) is a major hurdle for obtaining sufficient quantity and quality hepatocytes during cell therapy in patients with liver failure. Intrahepatic cholangiocyte organoids (ICOs) derived from intrahepatic bile ducts differentiate into both hepatocytes and cholangiocytes in vitro. Here, we studied in vivo effects of transplanting ICOs and Hep in chronic liver injury mice models. Well characterized primary mouse ICOs and Hep were mixed in decellularized liver (DCL) matrix hydrogels and injected into the subcapsular left lateral liver lobe of CCl4-induced liver injury models whereas mice given DCL alone were in the sham group. Two weeks post-transplantation, transplanted liver lobes were collected and studied by histology and RNA sequencing. Transplanted animals did not exhibit any tumors, mortality or morbidity. Mice livers transplanted with ICOs had increased cellular proliferation and vascularization as compared to Hep transplanted mice or sham. Collagen deposition in the liver was significantly reduced and serum albumin levels were significantly increased in transplanted groups compared to the sham group. Expression of genes associated with hepatocyte differentiation was highest in Hep transplanted livers among the three groups, but they were also upregulated in ICO transplanted livers compared to sham. Our study demonstrates that ICOs encapsulated in DCL hydrogels when transplanted in chronically injured mice livers engraft well and show hepatocyte differentiation and reduction of fibrosis, indicating that hydrogel transplanted cholangiocyte organoids may serve as an efficient cell source and therapy for renewal of hepatocytes, restoration of hepatocyte functions and resolution of liver injury.

Molecular Biological Mechanisms of Action of Chrysophanol in Hepatic Stellate Cells Activated by Hepatic B Virus X Based on Network Pharmacology

INTRODUCTION

Chrysophanol (Cho) is a natural anthraquinone with biological effects such as inducing ferroptosis and anticancer activity. The hepatitis B virus X protein (HBx) is essential for HBV replication. We aimed to identify the key pathways in HBx-induced hepatic stellate cell (HSC) activation and to characterize the potential mechanisms of action of Cho against liver fibrosis.

METHODS

HSC-T6 cells were transfected with FLAG (control group) or FLAG-HBx (HBx group), and RNA sequencing and Western blotting analysis were conducted to assess the effects of HBx and Cho on specific molecular targets and signaling pathways.

RESULTS

Gene ontology and pathway analyses indicated that the genes targeted by HBx participate in immunological responses, chemokine and cytokine activity, cell-substrate adhesion, extracellular matrix organization, growth factor binding, defense responses, and antigen processing and presentation. RNA-seq and Western blotting data revealed that HBx-activated HSC-T6 cells exhibited upregulated expression of mammalian target of rapamycin (mTOR), phosphorylated mTOR (p-mTOR), S6, phosphorylated S6 (p-S6), peroxisome proliferator-activated receptor (PPAR-α), phosphorylated-PPAR-α (p-PPAR-α), CYP27, α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF), and Integrin-β1, which was reversed after treatment with Cho. These results were also verified in a HBx-activated HSC-T6 and LX-2 cell model and thioacetamide-induced liver fibrosis mouse model.

CONCLUSIONS

Thus, our findings indicate that Cho ameliorates HBx-induced HSC activation and liver fibrosis via inhibition of the mTOR and PPARs signaling pathways, suggesting that Cho is a potential therapeutic for chronic liver inflammation-mediated diseases.

Comprehensive evaluation of the mechanism of human adipose mesenchymal stem cells ameliorating liver fibrosis by transcriptomics and metabolomics analysis

Liver fibrosis is a chronic liver disease with progressive wound healing reaction caused by liver injury. Currently, there is no FDA approved drugs for liver fibrosis. Human adipose mesenchymal stem cells (hADSCs) have shown remarkable therapeutic effects in liver diseases. However, few studies have evaluated the therapeutic role of hADSCs in liver fibrosis, and the detailed mechanism of action is unknown. Here, we investigated the in vitro and in vivo anti-fibrosis efficacy of hADSCs and identified important metabolic changes and detailed mechanisms through transcriptomic and metabolomic analyses. We found that hADSCs could inhibit the proliferation of activated hepatic stellate cells (HSCs), promote their apoptosis, and effectively inhibit the expression of pro-fibrotic protein. It can significantly reduce collagen deposition and liver injury, improve liver function and alleviate liver inflammation in cirrhotic mouse models. In addition, transcriptome analysis revealed that the key mechanism of hADSCs against liver fibrosis is the regulation of AGE-RAGE signaling pathway. Metabolic analysis showed that hADSCs influenced changes of metabolites in lipid metabolism. Therefore, our study shows that hADSCs could reduce the activation of hepatic stellate cells and inhibit the progression of liver fibrosis, which has important potential in the treatment of liver fibrosis as well as other refractory chronic liver diseases.

Enhanced In Vitro Efficacy of Verbascoside in Suppressing Hepatic Stellate Cell Activation via ROS Scavenging with Reverse Microemulsion

Numerous approaches targeting hepatic stellate cells (HSCs) have emerged as pivotal therapeutic strategies to mitigate liver fibrosis and are currently undergoing clinical trials. The investigation of herbal drugs or isolated natural active compounds is particularly valuable, due to their multifaceted functions and low risk of side effects. Recent studies have hinted at the potential efficacy of verbascoside (VB) in ameliorating renal and lung fibrosis, yet its impact on hepatic fibrosis remains to be elucidated. This study aims to evaluate the potential effects of VB on liver fibrosis by assessing its ability to inhibit HSC activation. VB demonstrated significant efficacy in suppressing the expression of fibrogenic genes in activated LX-2 cells. Additionally, VB inhibited the migration and proliferation of these activated HSCs by scavenging reactive oxygen species (ROS) and downregulating the AMPK pathway. Furthermore, a biosafe reverse microemulsion loaded with VB (VB-ME) was developed to improve VB's instability and low bioavailability. The optimal formulation of VB-ME was meticulously characterized, revealing substantial enhancements in cellular uptake, ROS-scavenging capacity, and the suppression of HSC activation.

Bioengineered MSCGFPCxcr2-Mmp13 Transplantation Alleviates Hepatic Fibrosis by Regulating Mammalian Target of Rapamycin Signaling

Aims: Hepatic fibrosis is the pathological change during chronic liver diseases (CLD) that turns into cirrhosis if not reversed timely. Allogenic mesenchymal stem cell (MSC) therapy is an alternative to liver transplantation for CLD. However, poor engraftment of the transplanted MSCs limits their therapeutic efficacy. MSCs express chemokine receptors that regulate their physiology. We observed several-fold increased expressions of Cxcl3 and decreased expression of Mmp13 in the fibrotic liver. Therefore, we bioengineered MSCs with stable overexpression of Cxcr2 (CXCL3-cognate receptor) and Mmp13, collagenase (MSCGFPCxcr2-Mmp13). Results: The CXCL3/CXCR2 axis significantly increased migration through the activation of AKT/ERK/mTOR signaling. These bioengineered MSCs transdifferentiated into hepatocyte-like cells (MSCGFPCxcr2-Mmp13-HLCs) that endured the drug-/hepatotoxicant-induced toxicity by significantly increasing the antioxidants-Nrf2 and Sod2, while decreasing the apoptosis-Cyt C, Casp3, Casp9, and drug-metabolizing enzyme-Cyp1A1, Cyp1A2, Cyp2E1 markers. Therapeutic transplantation of MSCGFPCxcr2-Mmp13 abrogated AAP-/CCl4-induced hepatic fibrosis in mice by CXCR2-mediated targeted engraftment and MMP-13-mediated reduction in collagen. Mechanistically, induction of CXCL3/CXCR2 axis-activated mTOR-p70S6K signaling led to increased targeted engraftment and modulation of the oxidative stress by increasing the expression and activity of nuclear Nrf2 and SOD2 expression in the regenerated hepatic tissues. A marked change in the fate of transplanted MSCGFPCxcr2-Mmp13 toward hepatocyte lineage demonstrated by co-immunostaining of GFP/HNF4α along with reduced COL1α1 facilitated the regeneration of the fibrotic liver. Innovation and Conclusions: Our study suggests the therapeutic role of allogenic Cxcr2/Mmp13-bioengineered MSC transplantation decreases the hepatic oxidative stress as an effective translational therapy for hepatic fibrosis mitigation-mediated liver regeneration.

Synthesis and preclinical evaluation of a 89Zr-labelled human single chain antibody for non-invasive detection of hepatic myofibroblasts in acute liver injury

Synaptophysin is expressed on fibrogenic hepatic myofibroblasts. C1-3 is a single chain human antibody (scAb) that binds specifically to synaptophysin on hepatic myofibroblasts, providing a targeting vector for novel in vivo imaging agents of chronic liver disease. C1-3 and a negative control scAb, CSBD9, were radiolabelled with zirconium-89 via desferrioxamine chelation to enable non-invasive molecular imaging with positron emission tomography (PET). DFO-scAb conjugates were characterised by gel electrophoresis (SDS-PAGE) and MALDI-TOF spectrometry, and 89Zr-labelled with high radiolabelling efficiency (99%). [89Zr]Zr-DFO-C1-3 exhibited high in vitro stability (> 99%) in mouse and human sera over 3 days at 25 and 37 °C. Activated hepatic myofibroblasts incubated with [89Zr]Zr-DFO-C1-3 displayed significantly higher internalised activity (59.46%, P = 0.001) compared to the [89Zr]Zr-DFO-CSBD9 control, indicating synaptophysin-mediated uptake and high binding specificity of [89Zr]Zr-DFO-C1-3. Mice with CCl4-induced acute liver damage exhibited significantly higher liver uptake of [89Zr]Zr-DFO-C1-3, compared to controls, confirmed by both Cerenkov imaging and ex vivo gamma counting (4.41 ± 0.19%ID/g, P < 0.0001). CCl4-induced liver damage and the number of hepatic myofibroblasts was confirmed by αSMA staining of liver sections. These findings indicate that [89Zr]Zr-DFO-C1-3 has promising utility as a PET imaging agent for non-invasive detection of hepatic myofibroblasts following acute liver injury.

The Protective Effects of Astaxanthin (AST) in the Liver of Weaned Piglets

During the weaning period, piglets are exposed to high levels of stress, which often causes problems with the digestive system. This stress also promotes the production of free radicals, resulting in oxidative stress. Astaxanthin (AST) stands out as one of the most potent antioxidants. Its resistance to light and heat makes it particularly valuable in compound feed production. This study was to determine the effect of AST impact on liver histology and gene expression in piglets. For our experiment, we used 16 weaned piglets of the PL breed, which we divided into two groups: Group I (control group with no AST supplementation) and Group II (supplemented with AST at 0.025 g/kg). Both feed mixtures were iso-proteins and iso-energetic, meeting the nutritional requirements of the piglets. The experiment lasted from day 35 to day 70 of the piglets' age, during which they had ad libitum access. The results indicate that the addition of AST prevents liver fibrosis due to reduced collagen deposition in the tissue. Analysis of gene expression supported these results. In the AST-supplemented group, we noted a decrease in NR1H3 expression, an increase in CYP7A1 expression, and reductions in the expression of NOTCH1 and CREB genes.

Integrative Transcriptomic Analysis Reveals Upregulated Apoptotic Signaling in Wound-Healing Pathway in Rat Liver Fibrosis Models

Liver fibrosis, defined by the aberrant accumulation of extracellular matrix proteins in liver tissue due to chronic inflammation, represents a pressing global health issue. In this study, we investigated the transcriptomic signatures of three independent liver fibrosis models induced by bile duct ligation, carbon tetrachloride, and dimethylnitrosamine (DMN) to unravel the pathological mechanisms underlying hepatic fibrosis. We observed significant changes in gene expression linked to key characteristics of liver fibrosis, with a distinctive correlation to the burn-wound-healing pathway. Building on these transcriptomic insights, we further probed the p53 signaling pathways within the DMN-induced rat liver fibrosis model, utilizing western blot analysis. We observed a pronounced elevation in p53 protein levels and heightened ratios of BAX/BCL2, cleaved/pro-CASPASE-3, and cleaved/full length-PARP in the livers of DMN-exposed rats. Furthermore, we discovered that orally administering oligonol-a polyphenol, derived from lychee, with anti-oxidative properties-effectively countered the overexpressions of pivotal apoptotic genes within these fibrotic models. In conclusion, our findings offer an in-depth understanding of the molecular alterations contributing to liver fibrosis, spotlighting the essential role of the apoptosis pathway tied to the burn-wound-healing process. Most importantly, our research proposes that regulating this pathway, specifically the balance of apoptosis, could serve as a potential therapeutic approach for treating liver fibrosis.

Transcriptional regulation of Glis2 in hepatic fibrosis

The role of Gli-similar 2 (Glis2) in hepatic fibrosis (HF) is controversial. In this study, we focused on the functional and molecular mechanisms involved in the Glis2-mediated activation of hepatic stellate cells (HSCs)-a milestone event leading to HF. The expression levels of Glis2 mRNA and protein were significantly decreased in the liver tissues of patients with severe HF and in mouse fibrotic liver tissues as well as HSCs activated by TGFβ1. Functional studies indicated that upregulated Glis2 significantly inhibited HSC activation and alleviated BDL-induced HF in mice. Downregulation of Glis2 was found to correlate significantly with DNA methylation of the Glis2 promoter mediated by methyltransferase 1 (DNMT1), which restricted the binding of hepatic nuclear factor 1-α (HNF1-α), a liver-specific transcription factor, to Glis2 promoters. In addition, the enrichment of DNMT1 in the Glis2 promoter region was mediated by metastasis-associated lung adenocarcinoma transcriptor-1 (MALAT1) lncRNA, leading to transcriptional silencing of Glis2 and activation of HSCs. In conclusion, our findings reveal that the upregulation of Glis2 can maintain the resting state of HSCs. The decreased expression of Glis2 under pathological conditions may lead to the occurrence and development of HF with the expression silencing of DNA methylation mediated by MALAT1 and DNMT1.

Exosomes derived from human adipose mesenchymal stem cells ameliorate hepatic fibrosis by inhibiting PI3K/Akt/mTOR pathway and remodeling choline metabolism

Liver fibrosis is a chronic liver disease with the presence of progressive wound healing response caused by liver injury. Currently, there are no approved therapies for liver fibrosis. Exosomes derived from human adipose mesenchymal stem cells (hADMSCs-Exo) have displayed a prominent therapeutic effect on liver diseases. However, few studies have evaluated therapeutic effect of hADMSCs-Exo in liver fibrosis and cirrhosis, and its precise mechanisms of action remain unclear. Herein, we investigated anti-fibrotic efficacy of hADMSCs-Exo in vitro and in vivo, and identified important metabolic changes and the detailed mechanism through transcriptomic and metabolomic profiling. We found hADMSCs-Exo could inhibit the proliferation of activated hepatic stellate cells through aggravating apoptosis and arresting G1 phase, effectively inhibiting the expression of profibrogenic proteins and epithelial-to-mesenchymal transition (EMT) in vitro. Moreover, it could significantly block collagen deposition and EMT process, improve liver function and reduce liver inflammation in liver cirrhosis mice model. The omics analysis revealed that the key mechanism of hADMSCs-Exo anti-hepatic fibrosis was the inhibition of PI3K/AKT/mTOR signaling pathway and affecting the changes of metabolites in lipid metabolism, and mainly regulating choline metabolism. CHPT1 activated by hADMSCs-Exo facilitated formation and maintenance of vesicular membranes. Thus, our study indicates that hADMSCs-Exo can attenuate hepatic stellate cell activation and suppress the progression of liver fibrosis, which holds the significant potential of hADMSCs-Exo for use as extracellular nanovesicles-based therapeutics in the treatment of liver fibrosis and possibly other intractable chronic liver diseases.

Linseed Oil Attenuates Liver Inflammation, Fatty Acid Accumulation, and Lipid Distribution in Periportal and Perivenous Hepatocytes Induced by a High-Carbohydrate Diet in Mice

We evaluated whether linseed oil (LO) modulates the effects of a high-carbohydrate diet (HCD) on liver inflammation, fatty acid (FA) accumulation, and lipid distribution in periportal and perivenous hepatocytes. The control group (control high-carbohydrate diet [HCD-C]) received an HCD with lard and soybean oil as the lipid source. The L10 and L100 groups received the HCD with 10% and 100% of LO as the lipid source, respectively. The animals were killed by decapitation before (day 0) and after receiving the diets. Liver FA composition, inflammation, and fibrogenesis gene expression were evaluated. Also, the percentage of lipid-occupied area in periportal end perivenous hepatocytes were measured. The L100 group exhibited a higher (P < .05) liver amount of omega-3 polyunsaturated FA (n-3 PUFA) and lower (P < .05) amounts of saturated FA (SFA), monounsaturated FA (MUFA), and omega-6 polyunsaturated FA (n-6 PUFA) compared with L10 or HCD-C mice. On day 56, interleukin 10 and type IV collagen gene expression were significantly upregulated and downregulated, respectively in L100. Also, the L100 group showed lower (P < .05) FA accumulation (i.e., total FA, SFA, MUFA, and n-6 PUFA). Also, L10 and L100 presented lower (P < .05) percentage of high lipid-containing portion in periportal and perivenous hepatocytes. We concluded that LO attenuation of liver inflammation promoted by an HCD is associated with increased liver n-3 PUFA levels, so modulating FA composition, deposition, and distribution in periportal and perivenous hepatocytes.

Glycine-β-muricholic acid antagonizes the intestinal farnesoid X receptor-ceramide axis and ameliorates NASH in mice

Nonalcoholic steatohepatitis (NASH) is a rapidly developing pathology around the world, with limited treatment options available. Some farnesoid X receptor (FXR) agonists have been applied in clinical trials for NASH, but side effects such as pruritus and low-density lipoprotein elevation have been reported. Intestinal FXR is recognized as a promising therapeutic target for metabolic diseases. Glycine-β-muricholic acid (Gly-MCA) is an intestine-specific FXR antagonist previously shown to have favorable metabolic effects on obesity and insulin resistance. Herein, we identify a role for Gly-MCA in the pathogenesis of NASH, and explore the underlying molecular mechanism. Gly-MCA improved lipid accumulation, inflammatory response, and collagen deposition in two different NASH models. Mechanistically, Gly-MCA decreased intestine-derived ceramides by suppressing ceramide synthesis-related genes via decreasing intestinal FXR signaling, leading to lower liver endoplasmic reticulum (ER) stress and proinflammatory cytokine production. The role of bile acid metabolism and adiposity was excluded in the suppression of NASH by Gly-MCA, and a correlation was found between intestine-derived ceramides and NASH severity. This study revealed that Gly-MCA, an intestine-specific FXR antagonist, has beneficial effects on NASH by reducing ceramide levels circulating to liver via lowering intestinal FXR signaling, and ceramide production, followed by decreased liver ER stress and NASH progression. Intestinal FXR is a promising drug target and Gly-MCA a novel agent for the prevention and treatment of NASH.

3D hESC exosomes enriched with miR-6766-3p ameliorates liver fibrosis by attenuating activated stellate cells through targeting the TGFβRII-SMADS pathway

BACKGROUND

Exosomes secreted from stem cells exerted salutary effects on the fibrotic liver. Herein, the roles of exosomes derived from human embryonic stem cell (hESC) in anti-fibrosis were extensively investigated. Compared with two-dimensional (2D) culture, the clinical and biological relevance of three-dimensional (3D) cell spheroids were greater because of their higher regeneration potential since they behave more like cells in vivo. In our study, exosomes derived from 3D human embryonic stem cells (hESC) spheroids and the monolayer (2D) hESCs were collected and compared the therapeutic potential for fibrotic liver in vitro and in vivo.

RESULTS

In vitro, PKH26 labeled-hESC-Exosomes were shown to be internalized and integrated into TGFβ-activated-LX2 cells, and reduced the expression of profibrogenic markers, thereby regulating cellular phenotypes. TPEF imaging indicated that PKH26-labeled-3D-hESC-Exsomes possessed an enhanced capacity to accumulate in the livers and exhibited more dramatic therapeutic potential in the injured livers of fibrosis mouse model. 3D-hESC-Exosomes decreased profibrogenic markers and liver injury markers, and improved the level of liver functioning proteins, eventually restoring liver function of fibrosis mice. miRNA array revealed a significant enrichment of miR-6766-3p in 3D-hESC-Exosomes, moreover, bioinformatics and dual luciferase reporter assay identified and confirmed the TGFβRII gene as the target of miR-6766-3p. Furthermore, the delivery of miR-6766-3p into activated-LX2 cells decreased cell proliferation, chemotaxis and profibrotic effects, and further investigation demonstrated that the expression of target gene TGFβRII and its downstream SMADs proteins, especially phosphorylated protein p-SMAD2/3 was also notably down-regulated by miR-6766-3p. These findings unveiled that miR-6766-3p in 3D-hESC-Exosomes inactivated SMADs signaling by inhibiting TGFβRII expression, consequently attenuating stellate cell activation and suppressing liver fibrosis.

CONCLUSIONS

Our results showed that miR-6766-3p in the 3D-hESC-Exosomes inactivates smads signaling by restraining TGFβRII expression, attenuated LX2 cell activation and suppressed liver fibrosis, suggesting that 3D-hESC-Exosome enriched-miR-6766-3p is a novel anti-fibrotic therapeutics for treating chronic liver disease. These results also proposed a significant strategy that 3D-Exo could be used as natural nanoparticles to rescue liver injury via delivering antifibrotic miR-6766-3p.

Inflammatory and Non-Inflammatory Mechanisms Controlling Cirrhosis Development

Simple Summary

The liver is continuously exposed to several harmful factors, subsequently activating sophisticated mechanisms set-up in order to repair and regenerate the damaged liver and hence to prevent its failure. When the injury becomes chronic, the regenerative response becomes perpetual and goes awry, leading to cirrhosis with a fatal liver dysfunction. Cirrhosis is a well-known risk factor for hepatocellular carcinoma (HCC), the most common, usually lethal, human primary liver neoplasm with very limited therapeutic options. Considering the pivotal role of immune factors in the development of cirrhosis, here we review and discuss the inflammatory pathways and components implicated in the development of cirrhosis. A better understanding of these circuits would help the design of novel strategies to prevent and treat cirrhosis and HCC, two lethal diseases.

Abstract

Because the liver is considered to be one of the most important metabolic organs in the body, it is continuously exposed to damaging environmental agents. Upon damage, several complex cellular and molecular mechanisms in charge of liver recovery and regeneration are activated to prevent the failure of the organ. When liver injury becomes chronic, the regenerative response goes awry and impairs the liver function, consequently leading to cirrhosis, a liver disorder that can cause patient death. Cirrhosis has a disrupted liver architecture and zonation, along with the presence of fibrosis and parenchymal nodules, known as regenerative nodules (RNs). Inflammatory cues contribute to the cirrhotic process in response to chronic damaging agents. Cirrhosis can progress to HCC, the most common and one of the most lethal liver cancers with unmet medical needs. Considering the essential role of inflammatory pathways in the development of cirrhosis, further understanding of the relationship between immune cells and the activation of RNs and fibrosis would guide the design of innovative therapeutic strategies to ameliorate the survival of cirrhotic and HCC patients. In this review, we will summarize the inflammatory mechanisms implicated in the development of cirrhosis.

A triterpenoid-enriched extract of bitter melon leaves alleviates hepatic fibrosis by inhibiting inflammatory responses in carbon tetrachloride-treated mice

Liver fibrosis is a progression of chronic liver disease characterized by excess deposition of fibrillary collagen. The aim of this study was to investigate the protective effect of a triterpenoid-enriched extract (TEE) from bitter melon leaves against carbon tetrachloride (CCl₄)-induced hepatic fibrosis in mice. Male ICR mice received TEE (100 or 150 mg kg^-1) by daily oral gavage for one week before starting CCl₄ administration and throughout the entire experimental period. After intraperitoneal injection of CCl₄ for nine weeks, serum and liver tissues of the mice were collected for biochemical, histopathological and molecular analyses. Our results showed that TEE supplementation reduced CCl₄-induced serum aspartate aminotransferase and alanine aminotransferase activities. Histopathological examinations revealed that CCl₄ administration results in hepatic fibrosis, while TEE supplementation significantly suppressed hepatic necroinflammation and collagen deposition. In addition, TEE supplementation decreased α-smooth muscle actin (α-SMA)-positive staining and protein levels of α-SMA and transforming growth factor-β1. TEE-supplemented mice had lower mRNA expression levels of interleukin-6, tumor necrosis factor-α, and toll-like receptor 4. Moreover, TEE (150 mg kg^-1) supplementation significantly reduced intrahepatic inflammatory Ly6C⁺ monocyte infiltration. We demonstrated that TEE could ameliorate hepatic fibrosis by regulating inflammatory cytokine secretion and α-SMA expression in the liver to reduce collagen accumulation.

Molecular updates on berberine in liver diseases: Bench to bedside

Liver diseases are life-threatening illnesses and are the major cause of mortality and morbidity worldwide. These may include liver fibrosis, liver cirrhosis, and drug-induced liver toxicity. Liver diseases have a wide prevalence globally and the fifth most common cause of death among all gastrointestinal disorders. Several novel therapeutic approaches have emerged for the therapy of liver diseases that may provide better clinical outcomes with improved safety. The use of phytochemicals for the amelioration of liver diseases has gained considerable popularity. Berberine (BBR), an isoquinoline alkaloid of the protoberberine type, has emerged as a promising molecule for the treatment of gastrointestinal disorders. Accumulating studies have proved the hepatoprotective effects of BBR. BBR has been shown to modulate multiple signaling pathways implicated in the pathogenesis of liver diseases including Akt/FoxO2, PPAR-γ, Nrf2, insulin, AMPK, mTOR, and epigenetic pathways. In the present review, we have emphasized the important pharmacological activities and mechanisms of BBR in liver diseases. Further, we have reviewed various pharmacokinetic and toxicological barriers of this promising phytoconstituent. Finally, formulation-based novel approaches are also summarized to overcome the clinical hurdles for BBR.

Antisense Tissue Factor Oligodeoxynucleotides Protected Diethyl Nitrosamine/Carbon Tetrachloride-Induced Liver Fibrosis Through Toll Like Receptor4-Tissue Factor-Protease Activated Receptor1 Pathway

Tissue factor (TF) is a blood coagulation factor that has several roles in many non-coagulant pathways involved in different pathological conditions such as angiogenesis, inflammation and fibrogenesis. Coagulation and inflammation are crosslinked with liver fibrosis where protease-activated receptor1 (PAR1) and toll-like receptor4 (TLR4) play a key role. Antisense oligodeoxynucleotides are strong modulators of gene expression. In the present study, antisense TF oligodeoxynucleotides (TFAS) was evaluated in treating liver fibrosis via suppression of TF gene expression. Liver fibrosis was induced in rats by a single administration of N-diethyl nitrosamine (DEN, 200 mg/kg; i. p.) followed by carbon tetrachloride (CCl4, 3 ml/kg; s. c.) once weekly for 6 weeks. Following fibrosis induction, liver TF expression was significantly upregulated along with liver enzymes activities and liver histopathological deterioration. Alpha smooth muscle actin (α-SMA) and transforming growth factor-1beta (TGF-1β) expression, tumor necrosis factor-alpha (TNF-α) and hydroxyproline content and collagen deposition were significantly elevated in the liver. Blocking of TF expression by TFAS injection (2.8 mg/kg; s. c.) once weekly for 6 weeks significantly restored liver enzymes activities and improved histopathological features along with decreasing the elevated α-SMA, TGF-1β, TNF-α, hydroxyproline and collagen. Moreover, TFAS decreased the expression of both PAR1 and TLR4 that were induced by liver fibrosis. In conclusion, we reported that blockage of TF expression by TFAS improved inflammatory and fibrotic changes associated with CCl4+DEN intoxication. In addition, we explored the potential crosslink between the TF, PAR1 and TLR4 in liver fibrogenesis. These findings offer a platform on which recovery from liver fibrosis could be mediated through targeting TF expression.

The Inside-Out of End-Stage Liver Disease: Hepatocytes are the Keystone

Chronic liver injury results in cirrhosis and end-stage liver disease (ESLD) which represents a leading cause of death worldwide, affecting people in their most productive years of life. Medical therapy can extend life, but the only definitive treatment is liver transplantation (LT). However, LT remains limited by access to quality donor organs and suboptimal long-term outcomes. The degeneration from healthy-functioning livers to cirrhosis and ESLD involves a dynamic process of hepatocyte damage, diminished hepatic function, and adaptation. However, the mechanisms responsible for deterioration of hepatocyte function and ultimately hepatic failure in man are poorly understood. We review the current understanding of cirrhosis and ESLD as a dynamic process and outline the current mechanisms associated with the development of hepatic failure from the clinical manifestations to energy adaptations, regeneration, and regulation of nuclear transcription factors. A new generation of therapeutics could target stabilization of hepatocyte differentiation and function to avoid the need for transplantation in patients with cirrhosis and ESLD.

Matrix metalloproteinase-8 (MMP-8) regulates the activation of hepatic stellate cells (HSCs) through the ERK-mediated pathway

Hepatic stellate cells (HSCs) are known to play a key role in the progression of liver fibrosis by producing excessive extracellular matrix (ECM). Matrix metalloproteinases (MMPs) belong to a family of endopeptidases, which have a well-established role in the degradation of ECM. Our study suggests that, besides the degradation of the extracellular matrix, matrix metalloproteinase-8 (MMP-8) has a non-canonical role in activating the quiescent HSCs to myofibroblasts by regulating the expression of Col1A1 and αSMA. We have identified that MMP-8 secreted from macrophages as a response to LPS stimulation activates HSCs via ERK1/2-dependent pathway. In addition to this, we determined that MMP-8 may regulate the homodimerization of c-Jun in LX-2 cells, during the trans-differentiation process from quiescent HSC to activate myofibroblasts. Macrophage-released MMP-8 plays a master role in activating the dormant HSCs to activate myofibroblasts through the Erk-mediated pathway and Jun cellular translocation leading to liver fibrosis. Significance MMP-8 can be used as a therapeutic target against liver fibrosis.

Cellular Interplay as a Consequence of Inflammatory Signals Leading to Liver Fibrosis Development

Inflammation has been known to be an important driver of fibrogenesis in the liver and onset of hepatic fibrosis. It starts off as a process meant to protect the liver from further damage, but it can become the main promoter of liver fibrosis. There are many inflammation-related pathways activated during liver fibrosis that lead to hepatic stellate cells (HSCs) activation and collagen-deposition in the liver. Such events are mostly modulated upstream of HSCs and involve signals from hepatocytes and innate immune cells. One particular event is represented by cell death during liver injury that generates multiple inflammatory signals that further trigger sterile inflammation and enhancement of inflammatory response. The assembly of inflammasome that responds to danger-associated molecular patterns (DAMPs) stimulates the release of pro-inflammatory cytokines and at the same time, initiates programmed cell death called pyroptosis. This review focuses on cellular and molecular mechanisms responsible for initiation and progress of inflammation in the liver.

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.

Insulin-Like Growth Factor Binding Protein-Related Protein 1 Activates Primary Hepatic Stellate Cells via Autophagy Regulated by the PI3K/Akt/mTOR Signaling Pathway

BACKGROUND

Autophagy is a self-degrading process. Previously, we showed that insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) is a novel transforming growth factor β1 (TGFβ1)-interacting factor in liver fibrosis; the role of TGFβ1-mediated autophagy in hepatic stellate cells (HSCs) activation has been investigated. However, whether autophagy is regulated by IGFBPrP1 remains unknown.

AIMS

We investigated the interactions among IGFBPrP1, autophagy, and activation of primary rat HSCs.

METHODS

Primary HSCs were separated from Sprague Dawley rats by two-step enzymatic digestion, and then, we overexpressed or inhibited IGFBPrP1 expression in HSCs under serum-starved condition. Autophagy inducer rapamycin or inhibitor 3-methyladenine (3MA) was used to assess the relationship between autophagy and HSCs activation.

RESULTS

We observed the expression of activation marker α-SMA and autophagy markers such as LC3B and Beclin1, which were significantly increased in HSCs treated with adenovirus vector harboring the IGFBPrP1 gene (AdIGFBPrP1) compared to cells cultured under serum-starved. In comparison, HSCs treated with shIGFBPrP1 showed opposite results. Furthermore, HSCs activation and autophagy increased when cells were treated with rapamycin, whereas opposite results were obtained when cells were treated with 3MA. AdIGFBPrP1 treatment downregulated the phosphorylation of Akt and mTOR.

CONCLUSION

Autophagy was induced in IGFBPrP1-treated primary HSCs, and IGFBPrP1-induced autophagy promoted the activation of HSCs and extracellular matrix expression, the underlying mechanism of which may involve the phosphatidylinositide 3-kinase/Akt/mTOR signaling pathway.

Farnesoid X receptor and bile acids regulate vitamin A storage

The nuclear receptor Farnesoid X Receptor (FXR) is activated by bile acids and controls multiple metabolic processes, including bile acid, lipid, carbohydrate, amino acid and energy metabolism. Vitamin A is needed for proper metabolic and immune control and requires bile acids for efficient intestinal absorption and storage in the liver. Here, we analyzed whether FXR regulates vitamin A metabolism. Compared to control animals, FXR-null mice showed strongly reduced (>90%) hepatic levels of retinol and retinyl palmitate and a significant reduction in lecithin retinol acyltransferase (LRAT), the enzyme responsible for hepatic vitamin A storage. Hepatic reintroduction of FXR in FXR-null mice induced vitamin A storage in the liver. Hepatic vitamin A levels were normal in intestine-specific FXR-null mice. Obeticholic acid (OCA, 3 weeks) treatment rapidly reduced (>60%) hepatic retinyl palmitate levels in mice, concurrent with strongly increased retinol levels (>5-fold). Similar, but milder effects were observed in cholic acid (12 weeks)-treated mice. OCA did not change hepatic LRAT protein levels, but strongly reduced all enzymes involved in hepatic retinyl ester hydrolysis, involving mostly post-transcriptional mechanisms. In conclusion, vitamin A metabolism in the mouse liver heavily depends on the FXR and FXR-targeted therapies may be prone to cause vitamin A-related pathologies.

TGF-β induces liver fibrosis via miRNA-181a-mediated down regulation of augmenter of liver regeneration in hepatic stellate cells

OBJECTIVE

To study the role of miRNA-181a and augmenter of liver regeneration in TGF-β-induced fibrosis in hepatic stellate cells.

METHODS

LX2 cells were treated with 20 ng/ml TGF-β for 24 h. miRNA-181a, ALR plasmid and empty vectors were transfected using siPORT NeoFx reagent. Cells were harvested after 48 h or 72 h of transfection for protein or RNA analysis. Western blotting was performed for ALR, TGF-β receptor II (TGFβ-RII), collagen 1A1 (COLL1A1), alpha-smooth muscle cell actin (α-SMA), rac1, E-cadherin and β-actin. Quantitative RT-PCR was performed for ALR, GAPDH, miRNA-181a or 5S rRNA.

RESULTS

TGF-β induced the expression of miRNA-181a, which in turn down-regulated ALR thereby induced the fibrosis markers, such as COLL1A1, α-SMA and rac1 in hepatic stellate cells. Over-expression of miRNA-181a down-regulated expression of ALR and up-regulated expression of fibrosis markers. On the other hand, ALR over-expression resulted in a decrease in miRNA-181a expression and fibrosis markers. Over-expression of ALR also inhibited the expression of TGFβ-RII and increased expression E-cadherin.

CONCLUSION

TGF-β induced miRNA-181a, which in turn induced fibrosis, at least in part, by inhibiting ALR. ALR inhibited TGF-β action by decreasing the expression of TGFβ-RII, thereby inhibiting miRNA-181a expression and fibrosis markers. ALR could serve as a potential molecule to inhibit liver fibrosis.

Endoplasmic Reticulum Stress in Metabolic Liver Diseases and Hepatic Fibrosis

Endoplasmic reticulum (ER) stress is a major contributor to liver disease and hepatic fibrosis, but the role it plays varies depending on the cause and progression of the disease. Furthermore, ER stress plays a distinct role in hepatocytes versus hepatic stellate cells (HSCs), which adds to the complexity of understanding ER stress and its downstream signaling through the unfolded protein response (UPR) in liver disease. Here, the authors focus on the current literature of ER stress in nonalcoholic and alcoholic fatty liver diseases, how ER stress impacts hepatocyte injury, and the role of ER stress in HSC activation and hepatic fibrosis. This review provides insight into the complex signaling and regulation of the UPR, parallels and distinctions between different liver diseases, and how ER stress may be targeted as an antisteatotic or antifibrotic therapy to limit the progression of liver disease.

Effect of cytoglobin overexpression on extracellular matrix component synthesis in human tenon fibroblasts

BACKGROUND

Conjunctival filtering bleb scar formation is the main reason for the failure of glaucoma filtration surgery. Cytoglobin (Cygb) has been reported to play an important role in extracellular matrix (ECM) remodeling, fibrosis and tissue damage repairing. This study aimed to investigate the role of Cygb in anti-scarring during excessive conjunctival wound healing after glaucoma filtration surgery.

METHODS

Cygb was overexpressed in human tenon fibroblasts (hTFs) by transfecting hTFs with lentiviral particles encoding pLenti6.2-FLAG-Cygb. Changes in the mRNA and protein levels of fibronectin, collagen I, collagen III, TGF-β1, and HIF1α were determined by RT-PCR and western blotting respectively.

RESULTS

After Cygb overexpression, hTFs displayed no significant changes in visual appearance and cell counts compared to controls. Whereas, Cygb overexpression significantly decreased the mRNA and protein expression levels of collagen I, collagen III and fibronectin compared with control (p < 0.01). There was also a statistically significant decrease in the mRNA and protein levels of TGF-β1 and HIF-1α in hTFs with overexpressed Cygb compared with control group (p < 0.05).

CONCLUSION

Our study provided evidence that overexpression of Cygb decreased the expression levels of fibronectin, collagen I, collagen III, TGF-β1 and HIF-1α in hTFs. Therefore, therapies targeting Cygb expression in hTFs may pave a new way for clinicians to solve the problem of post-glaucoma surgery scarring.

Transforming growth factor β (TGFβ) cross-talk with the unfolded protein response is critical for hepatic stellate cell activation

Transforming growth factor β (TGFβ) potently activates hepatic stellate cells (HSCs), which promotes production and secretion of extracellular matrix (ECM) proteins and hepatic fibrogenesis. Increased ECM synthesis and secretion in response to TGFβ is associated with endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). TGFβ and UPR signaling pathways are tightly intertwined during HSC activation, but the regulatory mechanism that connects these two pathways is poorly understood. Here, we found that TGFβ treatment of immortalized HSCs (i.e. LX-2 cells) induces phosphorylation of the UPR sensor inositol-requiring enzyme 1α (IRE1α) in a SMAD2/3-procollagen I-dependent manner. We further show that IRE1α mediates HSC activation downstream of TGFβ and that its role depends on activation of a signaling cascade involving apoptosis signaling kinase 1 (ASK1) and c-Jun N-terminal kinase (JNK). ASK1-JNK signaling promoted phosphorylation of the UPR-associated transcription factor CCAAT/enhancer binding protein β (C/EBPβ), which is crucial for TGFβ- or IRE1α-mediated LX-2 activation. Pharmacological inhibition of C/EBPβ expression with the antiviral drug adefovir dipivoxil attenuated TGFβ-mediated activation of LX-2 or primary rat HSCs in vitro and hepatic fibrogenesis in vivo Finally, we identified a critical relationship between C/EBPβ and the transcriptional regulator p300 during HSC activation. p300 knockdown disrupted TGFβ- or UPR-induced HSC activation, and pharmacological inhibition of the C/EBPβ-p300 complex decreased TGFβ-induced HSC activation. These results indicate that TGFβ-induced IRE1α signaling is critical for HSC activation through a C/EBPβ-p300-dependent mechanism and suggest C/EBPβ as a druggable target for managing fibrosis.

Distinctiveness in virological features and pathogenic potentials of subgenotypes D1, D2, D3 and D5 of Hepatitis B virus

Distinct clinical features of HBV infection have been associated with different viral genotype/subgenotype. HBV Genotype-D comprised of 10 subgenotypes, D1–D10, whose clinical implications still remain elusive. We investigated for the first-time, the virologic characteristics and cytopathic effects of four non-recombinant D-subgenotypes, D1/D2/D3/D5. Expressions of viral/host genes were evaluated in Huh7 cells transfected with full-length, linear-monomers of HBV/D-subgenotypes or pGL3-Basic vector carrying subgenotype-specific HBx. Intracellular HBV-DNA and pregenomic-RNA levels were high in D1/D2 than D3/D5. Expressions of PreC-mRNA and HBx were highest for D2 and D1 respectively, whereas PreS2/S-transcript was significantly reduced in D5. Increased apoptotic cell death and marked upregulation in caspase-3/Bax/TNF-R1/FasR/TRAIL-R1/ROS/MCP-1/IP-10/MIP-1β expression were noticed specifically in D2- and also in D3-transfected cells, while D5 resulted in over-expression of ER-stress-markers. D-subgenotype-transfected Huh7 cells were co-cultured with PBMC of healthy-donors or LX-2 cells and significant increase in pro-inflammatory cytokines in PBMC and fibrogenic-markers in LX-2 were noticed in presence of D2/D3. Further, Huh7 cells transfected with D1, in particular and also D5, displayed remarkable induction of EMT-markers and high proliferative/migratory abilities. Collectively, our results demonstrated that D2/D3 were more associated with hepatic apoptosis/inflammation/fibrosis and D1/D5 with increased risk of hepatocarcinogenesis and emphasize the need for determining HBV-subgenotype in clinical practice.

Bone marrow-derived monocyte infusion improves hepatic fibrosis by decreasing osteopontin, TGF-β1, IL-13 and oxidative stress

AIM

To evaluate the therapeutic effects of bone marrow-derived CD11b⁺CD14⁺ monocytes in a murine model of chronic liver damage.

METHODS

Chronic liver damage was induced in C57BL/6 mice by administration of carbon tetrachloride and ethanol for 6 mo. Bone marrow-derived monocytes isolated by immunomagnetic separation were used for therapy. The cell transplantation effects were evaluated by morphometry, biochemical assessment, immunohistochemistry and enzyme-linked immunosorbent assay.

RESULTS

CD11b⁺CD14⁺ monocyte therapy significantly reduced liver fibrosis and increased hepatic glutathione levels. Levels of pro-inflammatory cytokines, including tumor necrosis factor-α, interleukin (IL)-6 and IL-1β, in addition to pro-fibrotic factors, such as IL-13, transforming growth factor-β1 and tissue inhibitor of metalloproteinase-1 also decreased, while IL-10 and matrix metalloproteinase-9 increased in the monocyte-treated group. CD11b⁺CD14⁺ monocyte transplantation caused significant changes in the hepatic expression of α-smooth muscle actin and osteopontin.

CONCLUSION

Monocyte therapy is capable of bringing about improvement of liver fibrosis by reducing oxidative stress and inflammation, as well as increasing anti-fibrogenic factors.

The pattern of IL-24/mda-7 and its cognate receptors expression following activation of human hepatic stellate cells

Activation of hepatic stellate cells (HSCs) is the pivotal event during liver fibrosis. Interleukin (IL)-24/melanoma differentiation-associated gene-7 (mda-7) has attracted attention in the pathophysiology of some diseases, while its role in activation/suppression of human HSCs is still unclear. It is important to elucidate whether the expression levels of the IL-24/mda-7 protein and its receptors in HSC cells are changed following activation. LX-2 cells, a human hepatic stellate cell line were activated by a combination of leptin and serum starvation. The activation state was evaluated through measuring the mRNA expression of profibrotic molecules, collagen-I, TIMP metalloproteinase inhibitor-1 and transforming growth factor-β. The expression of IL-24/mda-7 was assessed in mRNA and protein levels by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and ELISA methods, respectively. Hence, the amount of IL-22R1 and IL-20R2 subunit expression was also compared in activated and normal LX-2 cells by RT-qPCR. The expression level of IL-24/mda-7 and its cognate receptors was detectable both in the normal and activated LX-2 cell line. Furthermore, in activated LX-2, a significant increase of IL24 expression either on IL-22R1 and IL-20R2 subunits was also noticeable in comparison to normal cells. The activation state of LX-2 cells caused significant changes of IL-24/mda-7 and its receptors expression. In addition, the elevation in IL-24/mda-7 during LX-2 cell activation, suggested that IL-24/mda-7 and its cognate receptors serve a possible role in the development of the fibrosis process. Therefore, IL-24/mda-7 and relevant signaling pathways may be employed as a target for fibrosis treatment.

Ethyl acetate fraction of Amomum xanthioides improves bile duct ligation-induced liver fibrosis of rat model via modulation of pro-fibrogenic cytokines

We investigated anti-hepatofibrotic effects of ethyl acetate fraction of Ammomum xanthoides (EFAX) using bile duct ligation (BDL)-induced hepatic fibrosis in a rat model. Male SD rats (6 weeks old) underwent BDL followed by 15 days of orall administration of EFAX (12.5, 25 or 50 mg/kg) or ursodeoxycholic acid (25 mg/kg). BDL caused animal death, ascites formation, alterations in serum biochemistries, and severe hepatic injury with excessive collagen deposition, whereas EFAX treatment significantly attenuated these effects. BDL markedly increased the pro-fibrogenic cytokines (TGF-β, PDGF-β, and CTGF) and the extracellular matrix indicators α-SMA, TIMP-1 and collagen type 1 in hepatic proteins and gene expression levels, which were notably normalized by EFAX treatment. EFAX also markedly normalized pro-fibrogenic signaling molecules including Smad2/3, Smad7, Akt, p44/42, and p38. We further explored EFAX mechanisms of actions using LX-2 cells (human derived hepatic stellate cell line). Pre-treatment with EFAX drastically attenuated the activation of α-SMA and Smad2/3, which are downstream molecules of TGF-β. These findings suggest that EFAX may be a potent anti-hepatofibrotic agent, and its corresponding mechanisms primarily involve the modulation of pro-fibrogenic cytokines.

Strategies and endpoints of antifibrotic drug trials: Summary and recommendations from the AASLD Emerging Trends Conference, Chicago, June 2014

There is an urgent need to develop antifibrotic therapies for chronic liver disease, and clarify which endpoints in antifibrotic trials will be acceptable to regulatory agencies. The American Association for the Study of Liver Diseases sponsored an endpoints conference to help accelerate the efficient testing of antifibrotic agents and develop recommendations on clinical trial design for liver fibrosis. In this review, we summarize the salient and novel elements of this conference and provide directions for future clinical trial design. The article follows the structure of the conference and is organized into five areas: (1) antifibrotic trial design; (2) preclinical proof-of-concept studies; (3) pharmacological targets, including rationale and lessons to learn; (4) rational drug design and development; and (5) consensus and recommendations on design of clinical trials in liver fibrosis. Expert overviews and collaborative discussions helped to summarize the key unmet needs and directions for the future, including: (1) greater clarification of at-risk populations and study groups; (2) standardization of all elements of drug discovery and testing; (3) standardization of clinical trial approaches; (4) accelerated development of improved noninvasive markers; and (5) need for exploration of potential off-target toxicities of future antifibrotic drugs.

Hepatocyte nuclear factor 4α induces a tendency of differentiation and activation of rat hepatic stellate cells

AIM: To investigate the effect of hepatocyte nuclear factor 4α (HNF4α) on the differentiation and transformation of hepatic stellate cells (HSCs).

METHODS: By constructing the recombinant adenovirus vector expressing HNF4α and HNF4α shRNA vector, and manipulating HNF4α expression in HSC-T6 cells, we explored the influence of HNF4α and its induction capacity in the differentiation of rat HSCs into hepatocytes.

RESULTS: With increased expression of HNF4α mediated by AdHNF4α, the relative expression of Nanog was downregulated in HSC-T6 cells (98.33 ± 12.33 vs 41.33 ± 5.67, P < 0.001). Consequently, the expression of G-P-6 and PEPCK was upregulated (G-P-6: 14.34 ± 3.33 vs 42.53 ± 5.87, P < 0.01; PEPCK: 10.10 ± 4.67 vs 56.56 ± 5.25, P < 0.001), the expression of AFP and ALB was positive, and the expression of Nanog, Type I collagen, α-SMA, and TIMP-1 was significantly decreased. HNF4α also downregulated vimentin expression and enhanced E-cadherin expression. The ultrastructure of HNF4α-induced cells had more mitochondria and ribosomes compared with the parental cells. After silencing HNF4α expression, EPCK, E-cadherin, AFP, and ALB were downregulated and α-SMA and vimentin were upregulated.

CONCLUSION: HNF4α can induce a tendency of differentiation of HSCs into hepatocyte-like cells. These findings may provide an effective way for the treatment of liver diseases.

Involvement of hepatic stellate cell cytoglobin in acute hepatocyte damage through the regulation of CYP2E1-mediated xenobiotic metabolism

Oxygen (O2) is required for cytochrome P450 (CYP)-dependent drug metabolism. Cytoglobin (CYGB) is a unique globin expressed exclusively in hepatic stellate cells (HSCs). However, its role in O2-dependent metabolism in neighboring hepatocytes remains unknown. This study provides evidence that CYGB in HSCs is involved in acetaminophen (N-acetyl-p-aminophenol; APAP)-induced hepatotoxicity. Serum alanine aminotransferase levels were higher in wild-type mice than in Cygb-null mice. Wild-type mice exhibited more severe hepatocyte necrosis around the central vein area compared with Cygb-null mice, thus indicating that CYGB deficiency protects against APAP-induced liver damage. Although no difference in the hepatic expression of CYP2E1, a key enzyme involved in APAP toxicity, was observed between wild-type and Cygb-null mice, the serum levels of the APAP metabolites cysteinyl-APAP and N-acetyl-cysteinyl-APAP were decreased in Cygb-null mice, suggesting reduced APAP metabolism in the livers of Cygb-null mice. In primary cultures, APAP-induced hepatocyte damage was increased by co-culturing with wild-type HSCs but not with Cygb-null HSCs. In addition, cell damage was markedly alleviated under low O2 condition (5% O2), suggesting the requirement of O2 for APAP toxicity. Carbon tetrachloride-induced liver injury (CYP2E1-dependent), but not lipopolysaccharide/D-galactosamine-induced injury (CYP2E1-independent), was similarly alleviated in Cygb-null mice. Considering the function of CYGB as O2 carrier, these results strongly support the hypothesis that HSCs are involved in the CYP2E1-mediated xenobiotic activation by augmenting O2 supply to hepatocytes. In conclusion, CYGB in HSCs contributes to the CYP-mediated metabolism of xenobiotics in hepatocytes by supplying O2 for enzymatic oxidation.

NADPH Oxidases in Chronic Liver Diseases

Oxidative stress is a common feature observed in a wide spectrum of chronic liver diseases including viral hepatitis, alcoholic, and nonalcoholic steatohepatitis. The nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) are emerging as major sources of reactive oxygen species (ROS). Several major isoforms are expressed in the liver, including NOX1, NOX2, and NOX4. While the phagocytic NOX2 has been known to play an important role in Kupffer cell and neutrophil phagocytic activity and inflammation, the nonphagocytic NOX homologues are increasingly recognized as key enzymes in oxidative injury and wound healing. In this review, we will summarize the current advances in knowledge on the regulatory pathways of NOX activation, their cellular distribution, and their role in the modulation of redox signaling in liver diseases.

Endoplasmic reticulum stress is the crossroads of autophagy, inflammation, and apoptosis signaling pathways and participates in liver fibrosis

OBJECTIVE

The objective of the review is to examine the crossroads of autophagy, inflammation, and apoptosis signaling pathways and their participation in liver fibrosis.

INTRODUCTION

Endoplasmic reticulum (ER) stress was emerged as a common feature relevant to the pathogenesis of diseases associated with organ fibrosis. However, the functional consequences of these alterations on ER stress and the possible involvement in liver fibrosis were currently largely unexplored. Here, we will survey the recent literature in the field and discuss recent insights focusing on some cellular models expressing mutant proteins involved in liver fibrosis.

METHODS

A computer-based online search with PubMed, Scopus and Web of Science databases was performed for articles published, concerning ER stress, adaptation, inflammation and apoptosis with relevance to liver fibrosis.

RESULTS AND CONCLUSIONS

Progression of liver fibrosis requires sustained inflammation leading to hepatocytes apoptosis through ER stress, whereas associated with activation of hepatic stellate cells (HSCs) into a fibrogenic and proliferative cell type. Faced with persistent and massive ER stress, HSCs adaptation starts to fail and apoptosis occurs in reversal of liver fibrosis, possibly mediated through calcium perturbations, unfolded protein response, and the pro-apoptotic transcription factor CHOP. Although limited in scope, current studies underscored that ER stress is tightly linked to adaptation, inflammation and apoptosis, and recent evidences suggested that these processes are related to the pathogenesis of liver fibrosis and its recovery.

Endocytosis of collagen by hepatic stellate cells regulates extracellular matrix dynamics

Hepatic stellate cells (HSCs) generate matrix, which in turn may also regulate HSCs function during liver fibrosis. We hypothesized that HSCs may endocytose matrix proteins to sense and respond to changes in microenvironment. Primary human HSCs, LX2, or mouse embryonic fibroblasts (MEFs) [wild-type; c-abl(-/-); or Yes, Src, and Fyn knockout mice (YSF(-/-))] were incubated with fluorescent-labeled collagen or gelatin. Fluorescence-activated cell sorting analysis and confocal microscopy were used for measuring cellular internalization of matrix proteins. Targeted PCR array and quantitative real-time PCR were used to evaluate gene expression changes. HSCs and LX2 cells endocytose collagens in a concentration- and time-dependent manner. Endocytosed collagen colocalized with Dextran 10K, a marker of macropinocytosis, and 5-ethylisopropyl amiloride, an inhibitor of macropinocytosis, reduced collagen internalization by 46%. Cytochalasin D and ML7 blocked collagen internalization by 47% and 45%, respectively, indicating that actin and myosin are critical for collagen endocytosis. Wortmannin and AKT inhibitor blocked collagen internalization by 70% and 89%, respectively, indicating that matrix macropinocytosis requires phosphoinositide-3-kinase (PI3K)/AKT signaling. Overexpression of dominant-negative dynamin-2 K44A blocked matrix internalization by 77%, indicating a role for dynamin-2 in matrix macropinocytosis. Whereas c-abl(-/-) MEF showed impaired matrix endocytosis, YSF(-/-) MEF surprisingly showed increased matrix endocytosis. It was also associated with complex gene regulations that related with matrix dynamics, including increased matrix metalloproteinase 9 (MMP-9) mRNA levels and zymographic activity. HSCs endocytose matrix proteins through macropinocytosis that requires a signaling network composed of PI3K/AKT, dynamin-2, and c-abl. Interaction with extracellular matrix regulates matrix dynamics through modulating multiple gene expressions including MMP-9.

Endoplasmic reticulum stress-induced hepatic stellate cell apoptosis through calcium-mediated JNK/P38 MAPK and Calpain/Caspase-12 pathways

Recent reports considered that it was the disturbance of calcium homeostasis and the accumulation of misfolded proteins in the endoplasmic reticulum (ER) that activated hepatic stellate cells (HSCs) apoptosis and promoted fibrosis resolution. However, the signal-transducing events that are activated by ER stress after HSCs activation were incompletely understood. In this study, we induced ER stress with thapsigargin (TG), and determined the activation of calpain and the cleavage of caspase by analyzing the protein levels and the correspondingly increased intracellular calcium levels and the induction of the proapoptotic transcription factor CHOP. Moreover, the phosphorylation of JNK and p38 MAPK were followed by the activation of the executioner caspases, caspase-3. As expected, preventing an increase in intracellular calcium levels using intracellular calcium chelators, EGTA, and BAPTA/AM, could substantially inhibit the phosphorylation of JNK and p38 MAPK, abolish the activation of calpains, namely caspase-12, caspase-9, and caspase-3, and provide significant protection for TG-treated activated HSCs. Interestingly, pretreatment with p38 MAPK inhibitor SB202190, JNK inhibitor SP600125, the pan-caspase inhibitor z-VAD-FMK, or calpain inhibitors calpeptin, significantly reduced the cell apoptosis and the cleavage of caspase-12 and caspase-3. However, pretreatment with z-VAD-FMK failed to reduce the activation of calpain. Additionally, pretreatment with SB202190 and SP600125 also decreased the expression of CHOP. Importantly, PDGF-induced collagen Col1α1 and α-smooth muscle actin (α-SMA), markers for the perpetuation phase of HSCs activation, were inhibited in TG-treated activated HSCs. These findings showed that the Calpain/Caspase-12 activation induced by ER stress and the JNK/p38 MAPK phosphorylation induced by the increase of intracellular calcium concentration releasing from ER are the novel signaling pathway underlying the molecular mechanism of fibrosis recovery.

Protective effect of astaxanthin on liver fibrosis through modulation of TGF-β1 expression and autophagy

Liver fibrosis is a common pathway leading to cirrhosis and a worldwide clinical issue. Astaxanthin is a red carotenoid pigment with antioxidant, anticancer, and anti-inflammatory properties. The aim of this study was to investigate the effect of astaxanthin on liver fibrosis and its potential protective mechanisms. Liver fibrosis was induced in a mouse model using CCL4 (intraperitoneal injection, three times a week for 8 weeks), and astaxanthin was administered everyday at three doses (20, 40, and 80 mg/kg). Pathological results indicated that astaxanthin significantly improved the pathological lesions of liver fibrosis. The levels of alanine aminotransferase aspartate aminotransferase and hydroxyproline were also significantly decreased by astaxanthin. The same results were confirmed in bile duct liagtion, (BDL) model. In addition, astaxanthin inhibited hepatic stellate cells (HSCs) activation and formation of extracellular matrix (ECM) by decreasing the expression of NF-κB and TGF-β1 and maintaining the balance between MMP2 and TIMP1. In addition, astaxanthin reduced energy production in HSCs by downregulating the level of autophagy. These results were simultaneously confirmed in vivo and in vitro. In conclusion, our study showed that 80 mg/kg astaxanthin had a significant protective effect on liver fibrosis by suppressing multiple profibrogenic factors.