Hepatic stellate cells and the reversal of fibrosis

Viral Hepatitis: Host Immune Interaction, Pathogenesis and New Therapeutic Strategies

Viral hepatitis is a major cause of liver illness worldwide. Despite advances in the understanding of these infections, the pathogenesis of hepatitis remains a complex process driven by intricate interactions between hepatitis viruses and host cells at the molecular level. This paper will examine in detail the dynamics of these host-pathogen interactions, highlighting the key mechanisms that regulate virus entry into the hepatocyte, their replication, evasion of immune responses, and induction of hepatocellular damage. The unique strategies employed by different hepatitis viruses, such as hepatitis B, C, D, and E viruses, to exploit metabolic and cell signaling pathways to their advantage will be discussed. At the same time, the innate and adaptive immune responses put in place by the host to counter viral infection will be analyzed. Special attention will be paid to genetic, epigenetic, and environmental factors that modulate individual susceptibility to different forms of viral hepatitis. In addition, this work will highlight the latest findings on the mechanisms of viral persistence leading to the chronic hepatitis state and the potential implications for the development of new therapeutic strategies. Fully understanding the complex host-pathogen interactions in viral hepatitis is crucial to identifying new therapeutic targets, developing more effective approaches for treatment, and shedding light on the mechanisms underlying progression to more advanced stages of liver damage.

Induction of hepatic fibrosis in mice with schistosomiasis by extracellular microRNA-30 derived from Schistosoma japonicum eggs

Background

Schistosomiasis is a zoonotic parasitic disorder induced by the infestation of schistosomes, a genus of trematodes. MicroRNAs (miRNAs) in egg-derived exosomes are crucial for modulating the host's immune responses and orchestrating the pathophysiological mechanisms. Although the exosomes secreted by S. japonicum contain abundant miRNAs, the specific roles of these miRNAs in the pathogenesis of schistosomiasis-induced hepatic fibrosis are yet to be comprehensively elucidated. The egg exosomes of S. japonicum secrete miRNA-30, a novel miRNA.

Methods

In vitro, the effect of miRNA-30 was evaluated by transfecting HSCs with miRNA mimics. The target gene biosignature for miRNA-30 was predicted using the miRDB software. The effect of miRNA-30 in hepatic fibrosis was evaluated by either elevating its expression in healthy mice or by inhibiting its activity in infected mice by administration of recombinant adeno-associated virus serotype eight vectors expressing miRNA-30 or miRNA sponges.

Results

This novel miRNA can activate hepatic stellate cells (HSCs), the prinary effector cells of hepatic fibrosis, in vitro, i.e., it significantly increases the fibrogenic factors Col1(α1), Col3(α1), and α-SMA at both mRNA and protein levels. In addition, miRNA-30 may activate HSCs by targeting the host RORA gene. In addition, in vivo experiments were conducted by administering a recombinant adeno-associated viral vector to modulate the expression levels of miRNA-30. The overexpression of miRNA-30 in healthy mice significantly elevated the expression of Col1(α1), Col3(α1), and α-SMA at both the transcriptomic and proteomic scales. This overexpression was coupled with a pronounced augmentation in the hepatic hydroxyproline content. Conversely, the in vivo silencing of miRNA-30 in infected mice induced a considerable reduction in the size of hepatic granulomas and areas of collagen deposition. Hence, in vivo, modulation of miRNA-30 expression may play a pivotal role in ameliorating the severity of hepatic fibrosis in mice afflicted with S. japonica.

Conclusions

The study results suggest that miRNA-30 may augment schistosomiasis-induced hepatic fibrosis through a probable interaction with the host RORA. Our study may improve the current theoretical framework regarding cross-species regulation by miRNAs of hepatic fibrosis in schistosomiasis.

Potential of Plant-Derived Compounds in Preventing and Reversing Organ Fibrosis and the Underlying Mechanisms

Increased production of extracellular matrix is a necessary response to tissue damage and stress. In a normal healing process, the increase in extracellular matrix is transient. In some instances; however, the increase in extracellular matrix can persist as fibrosis, leading to deleterious alterations in organ structure, biomechanical properties, and function. Indeed, fibrosis is now appreciated to be an important cause of mortality and morbidity. Extensive research has illustrated that fibrosis can be slowed, arrested or even reversed; however, few drugs have been approved specifically for anti-fibrotic treatment. This is in part due to the complex pathways responsible for fibrogenesis and the undesirable side effects of drugs targeting these pathways. Natural products have been utilized for thousands of years as a major component of traditional medicine and currently account for almost one-third of drugs used clinically worldwide. A variety of plant-derived compounds have been demonstrated to have preventative or even reversal effects on fibrosis. This review will discuss the effects and the underlying mechanisms of some of the major plant-derived compounds that have been identified to impact fibrosis.

Redox Biology and Liver Fibrosis

Hepatic fibrosis is a complex process that develops in chronic liver diseases. Even though the initiation and progression of fibrosis rely on the underlying etiology, mutual mechanisms can be recognized and targeted for therapeutic purposes. Irrespective of the primary cause of liver disease, persistent damage to parenchymal cells triggers the overproduction of reactive species, with the consequent disruption of redox balance. Reactive species are important mediators for the homeostasis of both hepatocytes and non-parenchymal liver cells. Indeed, other than acting as cytotoxic agents, reactive species are able to modulate specific signaling pathways that may be relevant to hepatic fibrogenesis. After a brief introduction to redox biology and the mechanisms of fibrogenesis, this review aims to summarize the current evidence of the involvement of redox-dependent pathways in liver fibrosis and focuses on possible therapeutic targets.

The effect of hepatic stellate cell derived-IL-11 on hepatocyte injury in hepatic fibrosis

AIMS

This study aimed to elucidate the role of Interleukin-11 (IL-11) in hepatic fibrosis (HF) and its potential as a therapeutic target for HF treatment.

MATERIALS AND METHODS

We investigated IL-11 expression in patients with varying degrees of liver injury through ELISA and immunohistochemistry. A CCl4-induced HF mouse model was constructed to study IL-11 expression and cell apoptosis using Western blotting (WB) and other techniques. The expression of IL-11 was silenced using rAAV8 in the mouse model. In vitro stimulation of hepatic stellate cells (LX-2) with TGF-β1, and of LO-2 cells with exogenous IL-11, were performed. Cell supernatants of TGF-β1-stimulated LX-2 were used to culture LO-2 cells, with apoptosis monitored via flow cytometry and WB.

KEY FINDINGS

Increased IL-11 levels were observed in patients and the HF mouse model, with silencing reducing IL-11 expression. In vitro experiments revealed increased endogenous IL-11 in TGF-β1-stimulated LX-2 cells and an increase in apoptotic index, IL11RA, and gp130 in IL-11-stimulated LO-2 cells. Cell apoptosis was reduced in the siRNA/IL11, siRNA/IL11RA, and anti-IL11 groups. WB and immunohistochemistry results showed upregulated p-JNK, p-ERK, and p-P53 expressions in the CCl4-induced HF mouse model and IL-11-treated LO-2 cells.

SIGNIFICANCE

Our findings suggest IL-11 enhances LX-2 cell activation and proliferation, and promotes LO-2 cell apoptosis through JNK/ERK signaling pathways. This suggests that targeting IL-11 secretion may serve as a potential therapeutic strategy for HF, providing a foundation for its clinical application in HF treatment.

Inflammatory liver tissue formation using oxygen permeable membrane based culture platform

During chronic liver injury, inflammation leads to liver fibrosis, particularly due to the activation of hepatic stellate cells (HSCs). The involvement of inflammatory cytokines in HSC activation and the interplay among different liver cells are elaborated. To examine their interactions in vitro, many cultured liver tissue models are performed in organoid or spheroid culture with random 3D structure. Herein, we demonstrated the hierarchical coculture of primary rat hepatocytes with non-parenchymal cells such as the human-derived HSC line (LX-2) and liver sinusoidal endothelial cell line (TMNK-1). The cocultured tissue had high usability with simple operation of separating solid and liquid phases with improved liver functions such as albumin production and hepatic cytochrome P450 3A4 activity. We also studied the effects of stimulation by both oxygen tension and the key pro-fibrogenic cytokine, transforming growth factor beta (TGF-β), on HSC activation. Gene expression of collagen type I and alpha-smooth muscle actin were enhanced in the hierarchical coculture under lower oxygen tension and TGF-β1 stimulation. Therefore, this hierarchical in vitro cocultured liver tissue could provide a useful platform as a disease model for elucidating the interactions of various liver cell types and biochemical signals in future liver fibrogenesis studies.

The Origin and Fate of Liver Myofibroblasts

Liver fibrosis of different etiologies is a serious health problem worldwide. There is no effective therapy available for liver fibrosis except the removal of the underlying cause of injury or liver transplantation. Development of liver fibrosis is caused by fibrogenic myofibroblasts that are not present in the normal liver, but rather activate from liver resident mesenchymal cells in response to chronic toxic or cholestatic injury. Many studies indicate that liver fibrosis is reversible when the causative agent is removed. Regression of liver fibrosis is associated with the disappearance of activated myofibroblasts and resorption of the fibrous scar. In this review, we discuss the results of genetic tracing and cell fate mapping of hepatic stellate cells and portal fibroblasts, their specific characteristics, and potential phenotypes. We summarize research progress in the understanding of the molecular mechanisms underlying the development and reversibility of liver fibrosis, including activation, apoptosis, and inactivation of myofibroblasts.

METTL14 reverses liver fibrosis by inhibiting NOVA2 through an m6A-YTHDF2-dependent mechanism

BACKGROUND

N6-methyladenosine (m6A), the most prevalent internal RNA modification in eukaryotic cells, is dynamically regulated in response to a wide range of physiological and pathological states. Nonetheless, the involvement of METTL14-induced m6A in liver fibrosis (LF) has yet to be established.

METHODS

In vitro, HSC cell lines with knock-down and overexpression of METTL14 were constructed, and the effects of METTL14 gene on the phenotypic function of activated HSCs were observed. The proliferation rate was measured by CCK8 and EDU, the cell proliferation cycle was measured by flow detector, the migration rate was measured by Transwell, and the contractility of F-actin was observed after phalloidin staining. The downstream target gene NOVA2 of METTL14 was screened by combined sequencing of MeRIP-seq and RNA-seq, combined with signal analysis. Adeno-associated virus (AAV) was injected into the tail vein in vivo to knock down the expression of METTL14, so as to further observe the role of METTL14 in the progress of LF.

RESULTS

our research showed that the methylase METTL14 content was decreased in hepatic tissue from patients with LF, leading to a lowered degree of m6A modification. Functionally, we discovered that knocking down m6A methyltransferase METTL14 led to increased HSC activation and a substantial worsening of LF. Mechanically, as shown in a multiomics study of HSCs, depleting METTL14 levels decreased m6A deposition onNOVA2 mRNA transcripts, which prompted the activation of YTHDF2 to detect and degrade the decrease of NOVA2 mRNA.

CONCLUSIONS

METTL14 functioned as a profibrotic gene by suppressing NOVA2 activity in a mechanism dependent on m6A-YTHDF2. Moreover, knocking down METTL14 exacerbated LF, while NOVA2 prevented its development and partly reversed the damage.

Cryptotanshinone induces apoptosis of activated hepatic stellate cells via modulating endoplasmic reticulum stress

BACKGROUND

Cryptotanshinone (CPT) has wide biological functions, including anti-oxidative, antifibrosis, and anti-inflammatory properties. However, the effect of CPT on hepatic fibrosis is unknown.

AIM

To investigate the effects of CPT treatment on hepatic fibrosis and its underlying mechanism of action.

METHODS

Hepatic stellate cells (HSCs) and normal hepatocytes were treated with different concentrations of CPT and salubrinal. The CCK-8 assay was used to determine cell viability. Flow cytometry was used to measure apoptosis and cell cycle arrest. Reverse transcription polymerase chain reaction (RT-PCR) and Western blot analyses were used to measure mRNA levels and protein expression of endoplasmic reticulum stress (ERS) signaling pathway related molecules, respectively. Carbon tetrachloride (CCL₄) was used to induce in vivo hepatic fibrosis in mice. Mice were treated with CPT and salubrinal, and blood and liver samples were collected for histopathological examination.

RESULTS

We found that CPT treatment significantly reduced fibrogenesis by modulating the synthesis and degradation of the extracellular matrix in vitro. CPT inhibited cell proliferation and induced cell cycle arrest at the G2/M phase in cultured HSCs. Furthermore, we found that CPT promoted apoptosis of activated HSCs by upregulating expression of ERS markers (CHOP and GRP78) and activating ERS pathway molecules (PERK, IRE1α, and ATF4), which were inhibited by salubrinal. Inhibition of ERS by salubrinal partially eliminated the therapeutic effect of CPT in our CCL₄-induced hepatic fibrosis mouse model.

CONCLUSION

CPT can promote apoptosis of HSCs and alleviate hepatic fibrosis through modulating the ERS pathway, which represents a promising strategy for treating hepatic fibrosis.

Discovery and development of benzene sulfonamide derivatives as anti-hepatic fibrosis agents

A novel benzene sulfonamide compound named IMB16-4 exhibits excellent anti-hepatic fibrosis activity in a recent study. To develop potential anti-hepatic fibrosis agents, a series of benzene sulfonamide derivatives were designed and synthesized based on the scaffold of the lead compound IMB16-4. As it turned out, most of the derivatives displayed potential anti-hepatic fibrosis activity, among which, compounds 11a, 11b, 11d, 13a, 36b, and 47b exhibited inhibition rates of 42.3%, 48.7%, 42.4%, 40.0%, 39.4%, and 49.3%, respectively, which were equivalent to the control IMB16-4 with an inhibition rate of 35.9%, Costunolide with an inhibition rate of 45.4%, and much more potent than that of Epigallocatechin gallate (EGCG) with an inhibition rate of 25.3%. Especially, compounds 46a, 46b, and 46c exhibited excellent anti-hepatic fibrosis activity with inhibition rates of 61.7%, 54.8%, and 60.7%, which were almost 1.5-fold inhibition rates of IMB16-4. In addition, compounds 46a, 46b, and 46c exhibited remarkable inhibitory activity in the gene expression of COL1A1, MMP-2, and the protein expression of COL1A1, FN, α-SMA, and TIMP-1 by inhibiting the JAK1-STAT1/3 pathway. These findings furnished valuable inspiration for the further development of anti-hepatic fibrosis agents.

Characterization and role of collagen gene expressing hepatic cells following partial hepatectomy in mice

BACKGROUND AND AIMS

The mechanism underlying liver regeneration following partial hepatectomy (PH) is not fully elucidated. We aimed to characterize collagen gene expressing hepatic cells following PH and examine their contribution to liver regeneration.

APPROACH AND RESULTS

Col-GFP mice, which express GFP under the control of the collagen gene promoter, were used to detect collagen gene expressing cells following PH. The GFP-expressing cells were analyzed via single-cell RNA sequencing (scRNA-seq). Additionally, Col-ER Cre/RFP and Col-ER Cre/DTA mice were utilized to examine the cell fates and functional roles of collagen gene expressing cells in liver regeneration, respectively. The number of collagen gene expressing cells was found to be increased on day 3 and subsequently decreased on day 7 following PH. ScRNA-seq analysis of sorted collagen gene expressing cells showed that the regenerating liver was characterized by three distinct hepatic stellate cell (HSC) clusters, including one representing classic myofibroblasts. The other HSC clusters included an intermediately activated HSC cluster and a proliferating HSC cluster. Of these, the latter cluster was absent in the CCl 4 -induced liver fibrosis model. Cell fate tracing analysis using Col-ER Cre/RFP mice demonstrated that the collagen gene expressing cells escaped death during regeneration and remained in an inactivated state in the liver. Further, depletion of these cells using Col-ER Cre/DTA mice resulted in impaired liver regeneration.

CONCLUSIONS

Heterogeneous HSC clusters, one of which was a unique proliferating cluster, were found to appear in the liver following PH. Collagen gene expressing cells, including HSCs, were found to promote liver regeneration.

Mesenchymal stem cells in fibrotic diseases-the two sides of the same coin

Fibrosis is caused by extensive deposition of extracellular matrix (ECM) components, which play a crucial role in injury repair. Fibrosis attributes to ~45% of all deaths worldwide. The molecular pathology of different fibrotic diseases varies, and a number of bioactive factors are involved in the pathogenic process. Mesenchymal stem cells (MSCs) are a type of multipotent stem cells that have promising therapeutic effects in the treatment of different diseases. Current updates of fibrotic pathogenesis reveal that residential MSCs may differentiate into myofibroblasts which lead to the fibrosis development. However, preclinical and clinical trials with autologous or allogeneic MSCs infusion demonstrate that MSCs can relieve the fibrotic diseases by modulating inflammation, regenerating damaged tissues, remodeling the ECMs, and modulating the death of stressed cells after implantation. A variety of animal models were developed to study the mechanisms behind different fibrotic tissues and test the preclinical efficacy of MSC therapy in these diseases. Furthermore, MSCs have been used for treating liver cirrhosis and pulmonary fibrosis patients in several clinical trials, leading to satisfactory clinical efficacy without severe adverse events. This review discusses the two opposite roles of residential MSCs and external MSCs in fibrotic diseases, and summarizes the current perspective of therapeutic mechanism of MSCs in fibrosis, through both laboratory study and clinical trials.

Fibrosis in Liver and Pancreas: a Review on Pathogenic Significance, Diagnostic Options, and Current Management Strategies

Inflammation is one of the most natural ways of the body's biological response against invading foreign pathogens or injured cells which eventually can lead to a chronic or acute productive response. Fibrosis is an end-stage event associated with an inflammatory response addressed with tissue hardening, discoloration, and most importantly overgrowth of associated tissue. Various organs at different diseased conditions are affected by fibrosis including the liver, pancreas, brain, kidney, and lung. Etiological factors including internal like inflammatory cytokines, growth factors, and oxidative stress and external like alcohol and viruses contribute to the development of fibrosis in both the liver and pancreas. More frequently, these organs are associated with pathogenic progression towards fibrosis from acute and chronic conditions and eventually fail in their functions. The pathogenesis of the organ-fibrotic events mainly depends on the activation of residential stellate cells; these cells help to accumulate collagen in respective organs. Various diagnostic options have been developed recently, and various therapeutic options are in trial to tackle fibrosis. In this review, an overview on fibrosis, the pathogenesis of fibrosis in the liver and pancreas, various diagnostic options developed in recent years, and possible present therapeutic measures to overcome options of fibrosis in the liver and pancreas; thus, restoring the functional status of organs is discussed.

CK2 blockade alleviates liver fibrosis by suppressing activation of hepatic stellate cells via the Hedgehog pathway

BACKGROUND AND PURPOSE

Liver fibrosis is a serious cause of morbidity and mortality worldwide characterized by accumulation of extracellular matrix produced by hepatic stellate cells (HSCs). The protein kinase CK2 is a pro-survival kinase overexpressed in human tumours. However, the biological role of CK2 in liver fibrosis is largely unknown. We aimed to investigate the mechanism by which CK2 promotes liver fibrosis.

EXPERIMENTAL APPROACH

In vitro, LX-2 cells were stimulated with transforming growth factor-β (TGF-β). HSCs were also isolated for research. In vivo, the adeno-associated virus AAV-sh-csnk2a1 was used to knockdown CK2α specifically in HSCs, and CX-4945 was used to pharmacologically inhibit the enzymatic activity of CK2 in murine models of fibrosis induced by carbon tetrachloride (CCl₄ ) and a 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet. Histological and biochemical analyses were performed to study the involvement of CK2 in regulation of fibrogenic and fibrolytic factors as well as activation properties of HSCs.

KEY RESULTS

HSC-specific genetic invalidation of CK2α or pharmacological inhibition of CK2 protected mice treated with CCl₄ or fed a DDC diet against liver fibrosis and HSC accumulation. Mechanistically, CK2α, which bound to Smoothened (SMO), was a positive regulator of the Hedgehog signal transduction pathway. CK2 prevented ubiquitination and proteasomal degradation of SMO, which was abolished by knockdown of CK2α or pharmacological inhibition of CK2.

CONCLUSIONS AND IMPLICATIONS

CK2 activation is critical to sustain the activated and fibrogenic phenotype of HSCs via SMO stabilization. Therefore, inactivation of CK2 by CX-4945 may be of therapeutic interest for liver fibrotic diseases.

Activated Hepatic Stellate Cells in Hepatocellular Carcinoma: Their Role as a Potential Target for Future Therapies

Hepatocellular carcinoma (HCC) is a global healthcare challenge, which affects more than 815,000 new cases every year. Activated hepatic stellate cells (aHSCs) remain the principal cells that drive HCC onset and growth. aHSCs suppress the anti-tumor immune response through interaction with different immune cells. They also increase the deposition of the extracellular matrix proteins, challenging the reversion of fibrosis and increasing HCC growth and metastasis. Therapy for HCC was reported to activate HSCs, which could explain the low efficacy of current treatments. Conversely, recent studies aimed at the deactivation of HSCs show that they have been able to inhibit HCC growth. In this review article, we discuss the role of aHSCs in HCC pathophysiology and therapy. Finally, we provide suggestions for the experimental implementation of HSCs in HCC therapies.

The novel role of ER protein TXNDC5 in the pathogenesis of organ fibrosis: mechanistic insights and therapeutic implications

Fibrosis-related disorders account for an enormous burden of disease-associated morbidity and mortality worldwide. Fibrosis is defined by excessive extracellular matrix deposition at fibrotic foci in the organ tissue following injury, resulting in abnormal architecture, impaired function and ultimately, organ failure. To date, there lacks effective pharmacological therapy to target fibrosis per se, highlighting the urgent need to identify novel drug targets against organ fibrosis. Recently, we have discovered the critical role of a fibroblasts-enriched endoplasmic reticulum protein disulfide isomerase (PDI), thioredoxin domain containing 5 (TXNDC5), in cardiac, pulmonary, renal and liver fibrosis, showing TXNDC5 is required for the activation of fibrogenic transforming growth factor-β signaling cascades depending on its catalytic activity as a PDI. Moreover, deletion of TXNDC5 in fibroblasts ameliorates organ fibrosis and preserves organ function by inhibiting myofibroblasts activation, proliferation and extracellular matrix production. In this review, we detailed the molecular and cellular mechanisms by which TXNDC5 promotes fibrogenesis in various tissue types and summarized potential therapeutic strategies targeting TXNDC5 to treat organ fibrosis.

Role of hepatic stellate cells in liver ischemia-reperfusion injury

Liver ischemia-reperfusion injury (IRI) is a major complication of liver trauma, resection, and transplantation. IRI may lead to liver dysfunction and failure, but effective approach to address it is still lacking. To better understand the cellular and molecular mechanisms of liver IRI, functional roles of numerous cell types, including hepatocytes, Kupffer cells, neutrophils, and sinusoidal endothelial cells, have been intensively studied. In contrast, hepatic stellate cells (HSCs), which are well recognized by their essential functions in facilitating liver protection and repair, have gained less attention in their role in IRI. This review provides a comprehensive summary of the effects of HSCs on the injury stage of liver IRI and their associated molecular mechanisms. In addition, we discuss the regulation of liver repair and regeneration after IRI by HSCs. Finally, we highlight unanswered questions and future avenues of research regarding contributions of HSCs to IRI in the liver.

KRT17 Promotes the Activation of HSCs via EMT in Liver Fibrosis

BACKGROUND AND AIMS

Although activation of hepatic stellate cells (HSCs) plays a central role in the development of liver fibrosis, the mechanism underlying the activation of HSCs remains unclear. Keratin 17 (KRT17), a member of the intermediate filament family, can regulate tumor cell proliferation and migration. The current study aimed to elucidate the role of KRT17 in the activation of HSCs and the mechanisms underlying liver fibrosis.

METHODS

The expression of KRT17 was determined using immunohistochemistry in tissue microarray. Western blotting and qRT-PCR assays were used to determine the KRT17 expression in fibrotic liver tissues obtained from human subjects and mice. LX-2 cells were treated with TGF-β1 recombinant protein and adipocyte differentiation mixture (MDI) mix to induce and reverse LX-2 cell activation, respectively, in order to explore the correlation between KRT17 and HSC activation. Additionally, cell proliferation and migration abilities of LX-2 cells transfected with KRT17-overexpressing plasmid or small interfering RNA were determined using CCK-8, flow cytometry, Transwell, and wound healing assays. Finally, rescue assay was used to explore the role of KRT17 in HSC activation and epithelial-mesenchymal transition (EMT).

RESULTS

The expression of KRT17 was higher in the human and mouse fibrotic liver tissues than in healthy liver tissues, and it was positively correlated with HSC activation. Upregulated KRT17 enhanced proliferation, migration, HSC activation and EMT in LX-2 cells, while knockdown of KRT17 reversed these effects. TGF-β1 recombinant protein accelerated KRT17-mediated EMT, HSC activation and proliferation, while TGF-β1 inhibitor counteracted the effect of KRT17 in vitro.

CONCLUSIONS

KRT17 promoted HSC activation, proliferation and EMT in hepatic fibrosis probably via TGF-β1 signaling, and KRT17 might serve as a therapeutic target for the treatment of liver fibrosis.

Cholesterol Induces Oxidative Stress, Mitochondrial Damage and Death in Hepatic Stellate Cells to Mitigate Liver Fibrosis in Mice Model of NASH

Liver fibrosis and its end-stage disease cirrhosis are major world health problems arising from chronic injury of the liver. In recent years, the hypothesis that hepatic stellate cells’ (HSCs’) activation and fibrosis can be mitigated by HSC apoptosis and cell death has become of interest. In the current study, we evaluated the effect of cholesterol and bile acids on HSC apoptosis and liver fibrosis. Male C57BL/6J mice (wild type), aged four to five weeks, were fed an AIN-93G based diet (normal diet, ND), ND diet + 1% (w/w) cholesterol (CHOL group), ND diet + 0.5% (w/w) cholic acid (CA group) or ND diet + 1% (w/w) cholesterol + 0.5% (w/w) cholic acid (CHOL + CA group). Female Mdr2(-/-) mice were also treated with ND with and without 1% cholesterol. The effect of cholesterol on liver fibrosis and HSC clearance was evaluated. In addition, we studied the mechanism of cholesterol-induced apoptosis in HSC-T6 and AML-12 hepatocyte cell lines. In animals treated with cholic acids, increased lipid peroxidation and fibrosis were observed after six weeks of treatment. However, addition of cholesterol to the diet of C57BL/6J mice led to HSC-specific apoptosis and resolution of liver fibrosis, verified by double-staining with active caspase and α smooth muscle actin antibodies. In Mdr2 (-/-) mice, a diet supplemented with cholesterol corrected fibrosis and induced active hepatic stellate cells’ clearance. HSC-T6 were found to be much more sensitive to cholesterol-induced oxidative stress, mitochondrial damage and apoptosis compared to hepatocytes. These results indicate that cholesterol may be a trigger of HSC lipid peroxidation and death in the liver in a model of non-alcoholic steatohepatitis. A high cholesterol-to-bile acid ratio may determine the trajectory of the liver disease toward mitigation of fibrosis.

The role of Mesothelin signaling in Portal Fibroblasts in the pathogenesis of cholestatic liver fibrosis

Liver fibrosis develops in response to chronic toxic or cholestatic injury, and is characterized by apoptosis of damaged hepatocytes, development of inflammatory responses, and activation of Collagen Type I producing myofibroblasts that make liver fibrotic. Two major cell types, Hepatic Stellate Cells (HSCs) and Portal Fibroblasts (PFs) are the major source of hepatic myofibroblasts. Hepatotoxic liver injury activates Hepatic Stellate Cells (aHSCs) to become myofibroblasts, while cholestatic liver injury activates both aHSCs and Portal Fibroblasts (aPFs). aPFs comprise the major population of myofibroblasts at the onset of cholestatic injury, while aHSCs are increasingly activated with fibrosis progression. Here we summarize our current understanding of the role of aPFs in the pathogenesis of cholestatic fibrosis, their unique features, and outline the potential mechanism of targeting aPFs in fibrotic liver.

Dihydromyricetin Reverses Thioacetamide-Induced Liver Fibrosis Through Inhibiting NF-κB-Mediated Inflammation and TGF-β1-Regulated of PI3K/Akt Signaling Pathway

As a natural active substance, dihydromyricetin (DHM) has been proven to have good hepatoprotective activity. However, the therapeutic effect of DHM on liver fibrosis, which has become a liver disease threatening the health of people around the world, has not been studied to date. The purpose of this study was to investigate the effect of DHM as a new nutritional supplement on thioacetamide (TAA)-induced liver fibrosis. The liver fibrosis model was established by intraperitoneal injection of TAA (200 mg/kg, every 3 days) for 8 weeks, and oral administration of DHM (20 mg/kg and 40 mg/kg, daily) after 4 weeks of TAA-induced liver fibrosis. The results showed that DHM treatment significantly inhibited the activities of alanine aminotransferase (ALT) (37.81 ± 7.62 U/L) and aspartate aminotransferase (AST) (55.18 ± 10.94 U/L) in serum of liver fibrosis mice, and increased the levels of superoxide dismutase (SOD) and glutathione (GSH) while reversed the level of malondialdehyde (MDA). In addition, histopathological examination illustrated that TAA induced the inflammatory infiltration, apoptosis and fibroatherosclerotic deposition in liver, which was further confirmed by western-blot and immunofluorescence staining. Moreover, DHM inhibited hepatocyte apoptosis by regulating the phosphorylation level of phosphatidylinositol 3-kinase (PI3K), protein kinase-B (AKT) and its downstream apoptotic protein family. Interestingly, immunofluorescence staining showed that DHM treatment significantly inhibited alpha smooth muscle actin (α-SMA), which was a marker of hepatic stellate cell activation, and regulated the expression of transforming growth factor (TGF-β1). Importantly, supplementation with DHM significantly inhibited the release of nuclear factor kappa-B (NF-κB) signaling pathway and pro-inflammatory factors in liver tissue induced by TAA, and improved liver fiber diseases, such as tumor necrosis factor alpha (TNF-α) and recombinant rat IL-1β (IL-1β). In conclusion, the evidence of this study revealed that DHM is a potential hepatoprotective and health factor, and which also provides the possibility for the treatment of liver fibrosis.

Noncoding RNAs Interactions in Hepatic Stellate Cells during Hepatic Fibrosis

Hepatic fibrosis is a reversible wound healing process following liver injury. Although this process is necessary for maintaining liver integrity, severe excessive extracellular matrix accumulation (ECM) could lead to permanent scar formation and destroy the liver structure. The activation of hepatic stellate cells (HSCs) is a key event in hepatic fibrosis. Previous studies show that most antifibrotic therapies focus on the apoptosis of HSCs and the prevention of HSC activation. Noncoding RNAs (ncRNAs) play a substantial role in HSC activation and are likely to be biomarkers or therapeutic targets for the treatment of hepatic fibrosis. This review summarizes and discusses the previously reported ncRNAs, including the microRNAs, long noncoding RNAs, and circular RNAs, highlighting their regulatory roles and interactions in the signaling pathways that regulate HSC activation in hepatic fibrosis.

Cellular and Molecular Mechanisms Underlying Liver Fibrosis Regression

Chronic liver injury of different etiologies may result in hepatic fibrosis, a scar formation process consisting in altered deposition of extracellular matrix. Progression of fibrosis can lead to impaired liver architecture and function, resulting in cirrhosis and organ failure. Although fibrosis was previous thought to be an irreversible process, recent evidence convincingly demonstrated resolution of fibrosis in different organs when the cause of injury is removed. In the liver, due to its high regenerative ability, the extent of fibrosis regression and reversion to normal architecture is higher than in other tissues, even in advanced disease. The mechanisms of liver fibrosis resolution can be recapitulated in the following main points: removal of injurious factors causing chronic hepatic damage, elimination, or inactivation of myofibroblasts (through various cell fates, including apoptosis, senescence, and reprogramming), inactivation of inflammatory response and induction of anti-inflammatory/restorative pathways, and degradation of extracellular matrix. In this review, we will discuss the major cellular and molecular mechanisms underlying the regression of fibrosis/cirrhosis and the potential therapeutic approaches aimed at reversing the fibrogenic process.

Liver regeneration and inflammation: from fundamental science to clinical applications

Liver regeneration is a complex process involving the crosstalk of multiple cell types, including hepatocytes, hepatic stellate cells, endothelial cells and inflammatory cells. The healthy liver is mitotically quiescent, but following toxic damage or resection the cells can rapidly enter the cell cycle to restore liver mass and function. During this process of regeneration, epithelial and non-parenchymal cells respond in a tightly coordinated fashion. Recent studies have described the interaction between inflammatory cells and a number of other cell types in the liver. In particular, macrophages can support biliary regeneration, contribute to fibrosis remodelling by repressing hepatic stellate cell activation and improve liver regeneration by scavenging dead or dying cells in situ. In this Review, we describe the mechanisms of tissue repair following damage, highlighting the close relationship between inflammation and liver regeneration, and discuss how recent findings can help design novel therapeutic approaches.

Hepatoprotective Effects of Selenium-Enriched Probiotics Supplementation on Heat-Stressed Wistar Rat Through Anti-Inflammatory and Antioxidant Effects

The purpose of this study was to elucidate the effects of selenium-enriched probiotics on the liver of heat-stressed Wistar rats. Ten-week-old male rats were assigned to four groups: control (Con); high temperature (HT); high temperature plus probiotics (HT + P: 10¹¹ CFU/mL Lactobacillus acidophilus and 10⁹ CFU/mL Saccharomyces cerevisiae); or high temperature plus selenium-enriched probiotics (HT + SeP: 0.3 mg/kg Se, 10¹¹ CFU/mL L. acidophilus and 10⁹ CFU/mL S. cerevisiae). The HT, HT + P, and HT + SeP groups were maintained at higher ambient temperature (40-42 °C), while the control group was kept at room temperature (25 °C). After 42 days of thermal exposure, blood and liver tissues were collected and analyzed for morphological and molecular markers of liver physiology. The body weight of rats in the HT group decreased but liver weight and live index were increased. Histological examination showed dilation of liver sinusoids and congestion of interstitial veins in HT group. Moreover, the histomorphology of the liver in HT + P and HT + SeP groups was restored, and the serum AST, ALT, ALP, LDH, and hepatic MDA level decreased significantly, but the serum total protein level and the liver SOD, T-AOC, and GSH-PX activities were increased significantly relative to the HT group. In addition, the mRNA level of Gpx1, SOD1, Nrf2, and Bcl-2 was significantly increased, while the expression level of Bax, IL-6, TNF-α, COX-2, NF-κB, α-SMA, TGFβ1, Collagen I, HSP70, and HSP90 was significantly decreased in liver tissues after SeP supplementation. We concluded that SeP can protect Wistar rats from oxidative stress, inflammation, apoptosis, and liver fibrosis induced by heat stress.

The bright side of fibroblasts: molecular signature and regenerative cues in major organs

Fibrosis is a pathologic process characterized by the replacement of parenchymal tissue by large amounts of extracellular matrix, which may lead to organ dysfunction and even death. Fibroblasts are classically associated to fibrosis and tissue repair, and seldom to regeneration. However, accumulating evidence supports a pro-regenerative role of fibroblasts in different organs. While some organs rely on fibroblasts for maintaining stem cell niches, others depend on fibroblast activity, particularly on secreted molecules that promote cell adhesion, migration, and proliferation, to guide the regenerative process. Herein we provide an up-to-date overview of fibroblast-derived regenerative signaling across different organs and discuss how this capacity may become compromised with aging. We further introduce a new paradigm for regenerative therapies based on reverting adult fibroblasts to a fetal/neonatal-like phenotype.

Parthenolide, bioactive compound of Chrysanthemum parthenium L., ameliorates fibrogenesis and inflammation in hepatic fibrosis via regulating the crosstalk of TLR4 and STAT3 signaling pathway

The current study focused on the regulatory effects of parthenolide (PNL), a bioactive component derived from Chrysanthemum parthenium L., against hepatic fibrosis via regulating the crosstalk of toll-like receptor 4 (TLR4) and signal transducer and activator of transcription 3 (STAT3) in activated hepatic stellate cells (HSCs). HSCs or Raw 264.7 macrophages were activated by TGF-β or LPS for 1 hr, respectively, and then treated with PNL, CLI-095 (TLR4 inhibitor), or Niclosamide (STAT3 inhibitor) for the indicated time to detect the crosstalk of TLR4 and STAT3. PNL significantly decreased the expressions of α-SMA, collagen I, and the ratio of TIMP1 and MMP13 in TGF-β-activated HSCs. PNL significantly reduced the releases of pro-inflammatory cytokines, including IL-6, IL-1β, IL-1α, IL-18, and regulated signaling P2X7r/NLRP3 axis activation. PNL obviously induced the apoptosis of activated HSCs by regulating bcl-2 and caspases family. PNL significantly inhibited the expressions of TLR4 and STAT3, including their downstream signaling. PNL could regulate the crosstalk of TLR4 and STAT3, which were verified by their inhibitors in activated HSCs or Raw 264.7 cell macrophages. Thus, PNL could decrease the expressions of fibrosis markers, reduce the releases of inflammatory cytokines, and also induce the apoptosis of activated HSCs. In conclusion, PNL could bi-directionally inhibit TLR4 and STAT3 signaling pathway, suggesting that blocking the crosstalk of TLR4 and STAT3 might be the potential mechanism of PNL against hepatic fibrosis.

Essential oil from the raw and vinegar-processed Rhizoma Curcumae ameliorate CCl4-induced liver fibrosis: integrating network pharmacology and molecular mechanism evaluation

Liver fibrosis, caused by multiple chronic liver injuries, is a known contributor to cirrhosis and even liver cancer. As a Traditional Chinese Medicine (TCM), Rhizoma curcumae has been extensively used in the treatment of liver fibrosis with satisfying therapeutic effects; however, its mechanism is unclear. The essential oil is the main bioactive component. The purpose of this study was to investigate the chemical profile and the pharmacological mechanisms of the essential oil of Rhizoma curcumae (EORC) against liver fibrosis by combining network pharmacology and transcriptomic technologies. A total of 37 active compounds were identified using the GC/MS system and literature mining, and the corresponding putative targets were predicted. Then, network pharmacology method was applied to identify the 168 candidate targets of EORC-alleviated liver fibrosis. String database and Cytoscape software were used to build the herb-compound-target network and protein-protein interactions (PPIs) network. Functional and pathway enrichment analysis indicated that EORC significantly influenced TGF-β1/Smads and PI3K/AKT pathways. Experimentally, we verified that EORC attenuated the severity and pathological changes during liver fibrosis progression based on the CCl4-induced liver fibrosis rat model. Transcriptomic technologies demonstrated that EORC ameliorated liver fibrosis partially by regulating the TGF-β1/Smads and PI3K/AKT pathways. In addition, the effect of vinegar-processed EORC was more significant than that of the raw one. Therefore, EORC can alleviate the severity of liver fibrosis through mechanisms predicted by network pharmacology and provide a basis for the further understanding of the application of EORC in the treatment of liver fibrosis.

Molecular and cellular mechanisms of liver fibrosis and its regression

Chronic liver injury leads to liver inflammation and fibrosis, through which activated myofibroblasts in the liver secrete extracellular matrix proteins that generate the fibrous scar. The primary source of these myofibroblasts are the resident hepatic stellate cells. Clinical and experimental liver fibrosis regresses when the causative agent is removed, which is associated with the elimination of these activated myofibroblasts and resorption of the fibrous scar. Understanding the mechanisms of liver fibrosis regression could identify new therapeutic targets to treat liver fibrosis. This Review summarizes studies of the molecular mechanisms underlying the reversibility of liver fibrosis, including apoptosis and the inactivation of hepatic stellate cells, the crosstalk between the liver and the systems that orchestrate the recruitment of bone marrow-derived macrophages (and other inflammatory cells) driving fibrosis resolution, and the interactions between various cell types that lead to the intracellular signalling that induces fibrosis or its regression. We also discuss strategies to target hepatic myofibroblasts (for example, via apoptosis or inactivation) and the myeloid cells that degrade the matrix (for example, via their recruitment to fibrotic liver) to facilitate fibrosis resolution and liver regeneration.

Effect of pioglitazone, as antidiabetic agent, on atheroma regression in type 2 diabetic patients: a systematic review and meta-analysis

Background

Pioglitazone’s role in the induction of atheroma regression in diabetics was suggested by several RCT. The aim of our study was to evaluate this role through a systematic review of all RCT conducted on this subject.

Methods

Literature was searched for relevant studies. We included all RCT that compared pioglitazone versus other antidiabetic agents. Mean differences of either AV or CIMT, HbA1C, HDL, and LDL between the two groups were used to assess the effect of pioglitazone versus alternative therapies.

Results

Six RCT were included with a total of 1180 patients. Pioglitazone was significantly superior to glimepiride and gliclazide in improving IMT. No significant difference was observed in overall AV, HbA1C, and LDL.

Conclusion

The latter findings confirm that anti-atheroma action of pioglitazone is not achieved through its antiglycemic or antidyslipidemia effects, but probably through a DNA-mediated effect, and may lead to its repurposing for reversal of organ fibrosis.

Vitamin D alleviates liver fibrosis by inhibiting histidine-rich calcium binding protein (HRC)

BACKGROUND

Liver fibrosis may progress toward cirrhosis and cancer without effective therapy. Here, we investigated the underlying mechanism of Vitamin D as a therapeutic approach.

METHODS

Carbon tetrachloride (CCL4)-induced mice model and transforming growth factor-β1 (TGF-β1) induced human hepatic stellate cell line LX-2 were used in vivo and in vitro. The fibrotic profiles, degree of liver injury and HRC expression were assessed by histology, Western blot, immunohistochemistry and Real-Time PCR. The proliferation of cells transfected with HRC ^+/+ and HRC^-/- plasmids was detected by MTS and cell cycle methods.

RESULTS

Vitamin D significantly suppressed the expression of HRC in liver fibrosis model both in vivo and in vitro (P < 0.01). The cell with overexpression of HRC significantly increased TGF-β1/Smad3 expressions and the percentage of the S peak in cell cycle (P < 0.05). However, Vitamin D can significantly reverse the levels of TGF-β1, Smad3 and p-smad3 caused by HRC in vitro. Furthermore, the overexpression of HRC in cell lines can attenuate the function of Vitamin D, suggesting that VD played a role by regulating HRC. Mechanically, HRC as the target of VDR is detected by CHIP method.

CONCLUSIONS

Vitamin D can delay hepatic fibrosis by reducing activation of hepatic stellate cells and TGF-β/Smad signaling through negative regulation of HRC. The findings revealed the important regulatory effect of Vitamin D in hepatic stellate cells and provided new insights into the therapeutic function of Vitamin D on liver fibrosis.

Traditional Chinese Medicine Fuzheng Huayu Prevents Development of Liver Fibrosis in Mice

Aim:

To investigate the therapeutic effect of FZHY on hepatic fibrosis in mice and to determine the mechanism of its action.

Methods:

Wild type mice were subjected to toxic (carbon tetrachloride, CCl₄) or cholestatic (bile duct ligation, BDL). Upon induction of liver fibrosis, mice were treated with FZHY (4.0g/kg, 2w, oral gavage) or vehicle (PBS). Livers were analyzed by Sirius Red staining, immunostaining and RT-PCR for profibrogenic and pro-inflammatory genes. The effect of FZHY on hepatocytes, inflammatory responses, activation of fibrogenic myofibroblasts, and ROS production was assessed.

Results:

FZHY strongly inhibited the development of CCl₄- and BDL-induced liver fibrosis in mice. Liver fibrosis was significantly improved in FZHY-treated mice, as demonstrated by reduced content of hepatic hydroxyproline and Sirius Red positive area. Moreover, the number of SMA ⁺and Desmin⁺ myofibroblasts was significantly reduced in the livers of FZHY-treated mice, and correlated with downregulation of the mRNA levels of α-SMA, collagen-α1(I), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), TGF-β1 and its receptor TGF-βRI, and platelet-derived growth factor-β (PDGF-β), suggesting that FZHY inhibits activation of fibrogenic myofibroblasts. Furthermore, administration of FZHY markedly decreased recruitment of F4/80⁺ inflammatory macrophages to the livers of CCl₄- and BDL-injured mice, and this effect was associated with downregulation of monocyte chemoattractant protein-1(MCP-1) and macrophage inflammatory protein-1 (MIP-1) mRNA. In addition, the lipid peroxidation products 4-hydroxynonenal (4-HNE) and malondialdehyde (MDA) were reduced, demonstrating that treatment with FZHY can effectively block ROS production in livers of CCl₄- and BDL-injured mice.

Conclusions:

Traditional Chinese Medicine FZHY has a variety of anti-fibrotic effects, including strong anti-oxidant, anti-inflammatory and anti-fibrotic effects on myeloid cells and hepatocytes. Although FZHY compound does not seem to directly affect HSCs, it regulates HSC activation via inhibition of macrophage recruitment to fibrotic liver.

Selective Targeting of αvβ5 Integrin in HepG2 Cell Line by RGDechi15D Peptide

Recently, the research community has become increasingly concerned with the receptor αvβ5, a member of the well-known integrin family. Different ongoing studies have evidenced that αvβ5 integrin regulates not only physiological processes but also a wide array of pathological events, suggesting the receptor as a valuable biomarker to specifically target for therapeutic/diagnostic purposes. Remarkably, in some tumors the involvement of the receptor in cell proliferation, tumor dissemination and angiogenesis is well-documented. In this scenario, the availability of a selective αvβ5 antagonist without ‘off-target’ protein effects may improve survival rate in patients with highly aggressive tumors, such as hepatocellular carcinoma. We recently reported a cyclic peptide, RGDechi15D, obtained by structure-activity studies. To our knowledge it represents the first peptide-based molecule reported in the literature able to specifically bind αvβ5 integrin and not cross react with αvβ3. Here we demonstrated the ability of the peptide to diminish both adhesion and invasion of HepG2 cells, an in vitro model system for hepatocellular carcinoma, to reduce the cell proliferation through an apoptotic process, and to interfere with the PI3K pathway. The peptide, also decreases the formation of new vessels in endothelial cells. Taken together these results indicate that the peptide can be considered a promising molecule with properties suited to be assessed in the future for its validation as a selective therapeutic/diagnostic weapon in hepatocarcinoma.

A Liver Biopsy Validation Pilot Study of Shear Wave Elastography, APRI, FIB-4, and Novel Serum Biomarkers for Liver Fibrosis Staging in Children With Chronic Viral Hepatitis

As liver biopsy in children poses inherent risks, noninvasive measures of liver fibrosis are needed. This was a cross-sectional, liver biopsy validation pilot study of 16 participants evaluating the ability of shear wave elastography, aspartate transaminase to platelet ratio index (APRI), fibrosis index based on the 4 factors, and novel serum biomarkers to stage liver fibrosis in children with chronic hepatitis B or C. There was very high intrasegmental shear wave speed variation in our participants and little correlation with fibrosis. APRI and monocyte chemoattractant protein (MCP-1) were higher in fibrosis stage F2-3 versus F0-1 (P = .02, P = .06, respectively). Soluble Fas (sFas) was lower in F2-3 versus F0-1 (P = .046). A logistic regression analysis calculated by (APRI × MCP-1)/sFas demonstrated an area under the receiver operating characteristic curve of 0.92 (P < .001), suggesting that this combination can differentiate fibrosis stage F0-1 from F2-3 in children with chronic viral hepatitis.

Non-coding RNA Associated Competitive Endogenous RNA Regulatory Network: Novel Therapeutic Approach in Liver Fibrosis

Liver fibrosis or scarring is the most common pathological feature caused by chronic liver injury, and is widely considered one of the primary causes of morbidity and mortality. It is primarily characterised by hepatic stellate cells (HSC) activation and excessive extracellular matrix (ECM) protein deposition. Overwhelming evidence suggests that the dysregulation of several noncoding RNAs (ncRNAs), mainly long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) contributes to the activation of HSC and progression of liver fibrosis. These ncRNAs not only bind to their target genes for the development and regression of liver fibrosis but also act as competing endogenous RNAs (ceRNAs) by sponging with miRNAs to form signaling cascades. Among these signaling cascades, lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA are critical modulators for the initiation, progression, and regression of liver fibrosis. Thus, targeting these interacting ncRNA cascades can serve as a novel and potential therapeutic target for inhibition of HSC activation and prevention and regression of liver fibrosis.

GNS561 acts as a potent anti-fibrotic and pro-fibrolytic agent in liver fibrosis through TGF-β1 inhibition

Background:

Hepatic fibrosis is the result of chronic liver injury that can progress to cirrhosis and lead to liver failure. Nevertheless, there are no anti-fibrotic drugs licensed for human use. Here, we investigated the anti-fibrotic activity of GNS561, a new lysosomotropic molecule with high liver tropism.

Methods:

The anti-fibrotic effect of GNS561 was determined in vitro using LX-2 hepatic stellate cells (HSCs) and primary human HSCs by studying cell viability, activity of caspases 3/7, autophagic flux, cathepsin maturation and activity, HSC activation and transforming growth factor-β1 (TGF-β1) maturation and signaling. The contribution of GNS561 lysosomotropism to its anti-fibrotic activity was assessed by increasing lysosomal pH. The potency of GNS561 on fibrosis was evaluated in vivo in a rat model of diethylnitrosamine-induced liver fibrosis.

Results:

GNS561 significantly decreased cell viability and promoted apoptosis. Disrupting the lysosomal pH gradient impaired its pharmacological effects, suggesting that GNS561 lysosomotropism mediated cell death. GNS561 impaired cathepsin activity, leading to defective TGF-β1 maturation and autophagic processes. Moreover, GNS561 decreased HSC activation and extracellular matrix deposition by downregulating TGF-β1/Smad and mitogen-activated proteine kinase signaling and inducing fibrolysis. Finally, oral administration of GNS561 (15 mg/kg per day) was well tolerated and attenuated diethylnitrosamine-induced liver fibrosis in this rat model (decrease of collagen deposition and of pro-fibrotic markers and increase of fibrolysis).

Conclusion:

GNS561 is a new potent lysosomotropic compound that could represent a valid medicinal option for hepatic fibrosis treatment through both its anti-fibrotic and its pro-fibrolytic effects. In addition, this study provides a rationale for targeting lysosomes as a promising therapeutic strategy in liver fibrosis.

Role of ncRNAs in modulation of liver fibrosis by extracellular vesicles

Extracellular vesicles (EVs) are small membrane vesicles carrying bioactive lipids, proteins and nucleic acids of the cell of origin. In particular, EVs carry non-coding RNAs (ncRNAs) and the vesicle membrane may protect them from degradation. Once released within the extracellular space, EVs can transfer their cargo, including ncRNAs, to neighboring or distant cells, thus inducing phenotypical and functional changes that may be relevant in several physio-pathological conditions. This review provides an overview of the role of EV-carried ncRNAs in the modulation of liver fibrosis. In particular, we focused on EV-associated microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) involved into the development of liver fibrosis and on the potential use of EV-associated ncRNAs as diagnostic and prognostic biomarkers of liver fibrosis.

The Matrisome, Inflammation, and Liver Disease

Chronic fatty liver disease is common worldwide. This disease is a spectrum of disease states, ranging from simple steatosis (fat accumulation) to inflammation, and eventually to fibrosis and cirrhosis if untreated. The fibrotic stage of chronic liver disease is primarily characterized by robust accumulation of extracellular matrix (ECM) proteins (collagens) that ultimately impairs the function of the organ. The role of the ECM in early stages of chronic liver disease is less well-understood, but recent research has demonstrated that several changes in the hepatic ECM in prefibrotic liver disease are not only present but may also contribute to disease progression. The purpose of this review is to summarize the established and proposed changes to the hepatic ECM that may contribute to inflammation during earlier stages of disease development, and to discuss potential mechanisms by which these changes may mediate the progression of the disease.

Specific Overexpression of Mitofusin-2 in Hepatic Stellate Cells Ameliorates Liver Fibrosis in Mice Model

Liver fibrosis is a chronic liver disease that could further develop to cirrhosis and liver carcinoma. Hepatic stellate cells (HSCs) are primary effector cells to initiate liver fibrosis. We aimed to explore the function and underlying mechanisms of mitochondrial fusion protein Mitofusin-2 (MFN2) in liver fibrosis. First, we utilized an alpha-smooth muscle actin promoter to overexpress MFN2 specifically in HSCs using adeno-associated virus (AAV) vector (AAV-MFN2). Overexpression of MFN2 was specifically achieved in HSC-T6 cells, but not in murine bone marrow-derived macrophages or hepatocyte AML-12 cells. We found that high expression of MFN2 induced apoptosis of HSC-T6 cells. Mechanistically, we demonstrated that high level of MFN2 inhibited TGF-β1/Smad signaling pathway, triggered downregulation of type I, type III, and type IV collagen, and antagonized the formation of factors associated with liver fibrosis. Furthermore, we found that overexpression of MFN2 using AAV-MFN2 ameliorated CCl₄-induced liver fibrosis in vivo with significantly decreased immune cell infiltration. Taken together, our findings indicate that MFN2 is critical in regulating apoptosis and liver fibrosis in HSCs, which might be a useful therapeutic target to treat liver fibrosis.

Antifibrotic effects of specific siRNA targeting connective tissue growth factor delivered by polyethyleneimine‑functionalized magnetic iron oxide nanoparticles on LX‑2 cells

Connective tissue growth factor (CTGF) is a possible key determinant of progressive fibrosis. Nanotechnology has been considered as a potential tool for developing novel drug delivery systems for various diseases, including liver fibrosis. The present study aimed to investigate the potential antifibrotic activity of CTGF small interfering RNA (siRNA) mediated by polyethyleneimine (PEI)-functionalized magnetic iron oxide (Fe₃O₄) nanoparticles (NPs) in LX-2 cells. PEI-Fe₃O₄/siRNA complexes were synthesized to facilitate siRNA delivery and were transfected into LX-2 cells. Laser confocal microscopy was employed to investigate the cell uptake of PEI-Fe₃O₄/siRNA complexes. Reverse transcription-quantitative PCR (RT-qPCR) and western blotting were used to verify the effect of gene silencing. The results showed that siRNA-loaded PEI-Fe₃O₄ exhibited low cytotoxicity. The transfection efficiency of PEI-Fe₃O₄/siRNA reached 73.8%, and RT-qPCR and western blotting demonstrated effective gene silencing. These results indicated that CTGF siRNA delivered by PEI-Fe₃O₄ NPs significantly reduces CTGF expression and collagen production in activated LX-2 cells, providing a basis for future in vivo studies.

Evaluation of NV556, a Novel Cyclophilin Inhibitor, as a Potential Antifibrotic Compound for Liver Fibrosis

Hepatic fibrosis can result as a pathological response to nonalcoholic steatohepatitis (NASH). Cirrhosis, the late stage of fibrosis, has been linked to poor survival and an increased risk of developing hepatocellular carcinoma, with limited treatment options available. Therefore, there is an unmet need for novel effective antifibrotic compounds. Cyclophilins are peptidyl-prolyl cis-trans isomerases that facilitate protein folding and conformational changes affecting the function of the targeted proteins. Due to their activity, cyclophilins have been presented as key factors in several stages of the fibrotic process. In this study, we investigated the antifibrotic effects of NV556, a novel potent sanglifehrin-based cyclophilin inhibitor, in vitro and in vivo. NV556 potential antifibrotic effect was evaluated in two well-established animal models of NASH, STAM, and methionine-choline-deficient (MCD) mice, as well as in an in vitro 3D human liver ECM culture of LX2 cells, a human hepatic stellate cell line. We demonstrate that NV556 decreased liver fibrosis in both STAM and MCD in vivo models and decreased collagen production in TGFβ1-activated hepatic stellate cells in vitro. Taken together, these results present NV556 as a potential candidate for the treatment of liver fibrosis.

MicroRNA-744/transforming growth factor β1 relationship regulates liver cirrhosis

BACKGROUND

MicroRNAs have added a new dimension to our understanding of liver cirrhosis (LC) and associated processes like the activation of hepatic stellate cells (HSCs).

METHODS

Serum samples were collected from 40 LC patients and 30 healthy donors. CCl4-induced LC mouse model in vivo and in vitro human HSC LX-2 and murine HSC JS-1 cells were researched.

RESULTS

The levels of serum microRNA (miR)-744 is inversely correlated with the severity of LC and is a reliable biomarker of LC. In CCl4-induced LC model, the abundance of miR-744 was reduced in both sera and livers compared with sham controls. Importantly, increasing miR-744 abundance with synthetic miR-744 Agomir alleviated liver fibrosis, a critical component of LC, while reducing miR-744 with Antagomir exacerbated it. To elucidate molecular mechanism underlying the suppressive role of miR-744 in LC, we observed that miR-744 and transforming growth factor β1 (TGFβ1) are inversely correlated in LC patients' sera as well as sera/livers from CCl4-induced LC mice. We demonstrated that miR-744 Agomir downregulated the expression of TGFβ1 and further confirmed that TGFβ1 mRNA was a bona fide miR-744 target in HSCs. Moreover, miR-744 Agomir reduced the degree of F-actin formation and cell proliferation while miR-744 Antagomir promoted these events, suggesting that miR-744 is a negative regulator of HSC activation.

CONCLUSIONS

MiR-744-led suppression in HSC activation is most likely through TGFβ1 because exogenous TGFβ1 nearly negated miR-744 Agomir's action. This study suggests that reduction of miR-744 is a reliable biomarker for LC and miR-744/TGFβ1 relationship is a key regulator of LC.

Bouchardatine analogue alleviates non-alcoholic hepatic fatty liver disease/non-alcoholic steatohepatitis in high-fat fed mice by inhibiting ATP synthase activity

BACKGROUND AND PURPOSE

Non-alcoholic hepatic fatty liver disease (NAFLD) is a manifestation of the metabolic syndrome in the liver and non-alcoholic steatohepatitis (NASH) represents its advanced stage. R17 derived from bouchardatine, shows benefits in the metabolic syndrome, but has not been tested in the liver. The present study examined the pharmacological effects of R17 in a model of NAFLD/NASH and its mode of action.

EXPERIMENTAL APPROACH

The effects of R17 were examined in mice fed a high-fat (HF) diet to induce the pathological characteristics of NAFLD/NASH and in cultures of HuH7 cells. We used histological and immunohistochemical techniques along with western blotting and siRNA. Generation of ROS and apoptosis were measured.

KEY RESULTS

Administration of R17 (20 mg·kg^-1 , i.p. every other day) for 5 weeks reversed HF-induced hepatic triglyceride content, inflammation (inflammatory cytokines and macrophage numbers), injury (hepatocyte ballooning and apoptosis, plasma levels of alanine aminotransferase and aspartate aminotransferase), and fibrogenesis (collagen deposition and mRNA expression of fibrosis markers). In cultured cells, R17 reduced cell steatosis from both lipogenesis and fatty acid influx. The attenuated inflammation and cell injury were associated with inhibition of both endoplasmic reticulum (ER) stress and oxidative stress. Notably, R17 activated the liver kinase B1-AMP-activated protein kinase (AMPK) pathway by inhibiting activity of ATP synthase, rather than direct stimulation of AMPK.

CONCLUSION AND IMPLICATIONS

R17 has therapeutic potential for NAFLD/NASH. Its mode of action involves the elimination of ER and oxidative stresses, possibly via activating the LKB1-AMPK axis by inhibiting the activity of ATP synthase.