Taurine attenuates activation of hepatic stellate cells by inhibiting autophagy and inducing ferroptosis

BACKGROUND Liver fibrosis is a compensatory response during the tissue repair process in chronic liver injury,and finally leads to liver cirrhosis or even hepatocellular carcinoma.The pathogenesis of hepatic fibrosis is associated with the progressive accumulation of activated hepatic stellate cells(HSCs),which can transdiffer-entiate into myofibroblasts to produce an excess of the extracellular matrix(ECM).Myofibroblasts are the main source of the excessive ECM responsible for hepatic fibrosis.Therefore,activated hepatic stellate cells(aHSCs),the principal ECM producing cells in the injured liver,are a promising therapeutic target for the treatment of hepatic fibrosis.AIM To explore the effect of taurine on aHSC proliferation and the mechanisms involved.METHODS Human HSCs(LX-2)were randomly divided into five groups:Normal control group,platelet-derived growth factor-BB(PDGF-BB)(20 ng/mL)treated group,mmol/L,respectively)with PDGF-BB(20 ng/mL)treated group.Cell Counting Kit-8 method was performed to evaluate the effect of taurine on the viability of aHSCs.Enzyme-linked immunosorbent assay was used to estimate the effect of taurine on the levels of reactive oxygen species(ROS),malondialdehyde,glutathione,and iron concen-tration.Transmission electron microscopy was applied to observe the effect of taurine on the autophagosomes and ferroptosis features in aHSCs.Quantitative real-time polymerase chain reaction and Western blot analysis were performed to detect the effect of taurine on the expression ofα-SMA,Collagen I,Fibronectin 1,LC3B,ATG5,Beclin 1,PTGS2,SLC7A11,and p62.RESULTS Taurine promoted the death of aHSCs and reduced the deposition of the ECM.Treatment with taurine could alleviate autophagy in HSCs to inhibit their activation,by decreasing autophagosome formation,downregulating LC3B and Beclin 1 protein expression,and upregulating p62 protein expression.Meanwhile,treatment with taurine triggered ferroptosis and ferritinophagy to eliminate aHSCs characterized by iron overload,lipid ROS accumu-lation,glutathione depletion,and lipid peroxidation.Furthermore,bioinformatics analysis demonstrated that taurine had a direct targeting effect on nuclear receptor coactivator 4,exhibiting the best average binding affinity of-20.99 kcal/mol.CONCLUSION Taurine exerts therapeutic effects on liver fibrosis via mechanisms that involve inhibition of autophagy and trigger of ferroptosis and ferritinophagy in HSCs to eliminate aHSCs.

HepG2.2.15-derived exosomes facilitate the activation and fibrosis of hepatic stellate cells

BACKGROUND The role of exosomes derived from HepG2.2.15 cells,which express hepatitis B virus(HBV)-related proteins,in triggering the activation of LX2 liver stellate cells and promoting liver fibrosis and cell proliferation remains elusive.The focus was on comprehending the relationship and influence of differentially expressed microRNAs(DE-miRNAs)within these exosomes.AIM To elucidate the effect of exosomes derived from HepG2.2.15 cells on the activation of hepatic stellate cell(HSC)LX2 and the progression of liver fibrosis.METHODS Exosomes from HepG2.2.15 cells,which express HBV-related proteins,were isolated from parental HepG2 and WRL68 cells.Western blotting was used to confirm the presence of the exosomal marker protein CD9.The activation of HSCs was assessed using oil red staining,whereas DiI staining facilitated the observation of exosomal uptake by LX2 cells.Additionally,we evaluated LX2 cell proliferation and fibrosis marker expression using 5-ethynyl-2′-deoxyuracil staining and western blotting,respectively.DE-miRNAs were analyzed using DESeq2.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathways were used to annotate the target genes of DE-miRNAs.RESULTS Exosomes from HepG2.2.15 cells were found to induced activation and enhanced proliferation and fibrosis in LX2 cells.A total of 27 miRNAs were differentially expressed in exosomes from HepG2.2.15 cells.GO analysis indicated that these DE-miRNA target genes were associated with cell differentiation,intracellular signal transduction,negative regulation of apoptosis,extracellular exosomes,and RNA binding.KEGG pathway analysis highlighted ubiquitin-mediated proteolysis,the MAPK signaling pathway,viral carcinogenesis,and the toll-like receptor signaling pathway,among others,as enriched in these targets.CONCLUSION These findings suggest that exosomes from HepG2.2.15 cells play a substantial role in the activation,proliferation,and fibrosis of LX2 cells and that DE-miRNAs within these exosomes contribute to the underlying mechanisms.

Perilipin 5 regulates hepatic stellate cell activation and high-fat diet-induced non-alcoholic fatty liver disease

Background:Nonalcoholic fatty liver disease(NAFLD)is one of the most common chronic liver diseases globally.Hepatic stellate cells(HSCs)are the major effector cells of liver fibrosis.HSCs contain abundant lipid droplets(LDs)in their cytoplasm during quiescence.Perilipin 5(PLIN 5)is a LD surface-associated protein that plays a crucial role in lipid homeostasis.However,little is known about the role of PLIN 5 in HSC activation.Methods:PLIN 5 was overexpressed in HSCs of Sprague–Dawley rats by lentivirus transfection.At the same time,PLIN 5 gene knockout mice were constructed and fed with a high-fat diet(HFD)for 20 weeks to study the role of PLIN 5 in NAFLD.The corresponding reagent kits were used to measure TG,GSH,Caspase 3 activity,ATP level,and mitochondrial DNA copy number.Metabolomic analysis of mice liver tissue metabolism was performed based on UPLC-MS/MS.AMPK,mitochondrial function,cell proliferation,and apoptosis-related genes and proteins were detected by western blotting and qPCR.Results:Overexpression of PLIN 5 in activated HSCs led to a decrease in ATP levels in mitochondria,inhibition of cell proliferation,and a significant increase in cell apoptosis through AMPK activation.In addition,compared with the HFD-fed C57BL/6J mice,PLIN 5 knockout mice fed with HFD showed reduced liver fat deposition,decreased LD abundance and size,and reduced liver fibrosis.Conclusion:These findings highlight the unique regulatory role of PLIN 5 in HSCs and the role of PLIN 5 in the fibrosis process of NAFLD.

Angiotensin-converting enzyme 2 improves liver fibrosis in mice by regulating autophagy of hepatic stellate cells

BACKGROUND Liver fibrosis is the common pathological process associated with the occurrence and development of various chronic liver diseases.At present,there is still a lack of effective prevention and treatment methods in clinical practice.Hepatic stellate cell(HSC)plays a key role in liver fibrogenesis.In recent years,the study of liver fibrosis targeting HSC autophagy has become a hot spot in this research field.Angiotensin-converting enzyme 2(ACE2)is a key negative regulator of reninangiotensin system,and its specific molecular mechanism on autophagy and liver fibrosis needs to be further explored.AIM To investigate the effect of ACE2 on hepatic fibrosis in mice by regulating HSC autophagy through the Adenosine monophosphate activates protein kinases(AMPK)/mammalian target of rapamycin(mTOR)pathway.METHODS Overexpression of ACE2 in a mouse liver fibrosis model was induced by injection of liver-specific recombinant adeno-associated virus ACE2 vector(rAAV2/8-ACE2).The degree of liver fibrosis was assessed by histopathological staining and the biomarkers in mouse serum were measured by Luminex multifactor analysis.The number of apoptotic HSCs was assessed by terminal deoxynucleoitidyl transferase-mediated dUTP nick-end labeling(TUNEL)and immunofluorescence staining.Transmission electron microscopy was used to identify the changes in the number of HSC autophagosomes.The effect of ACE2 overexpression on Wu Y et al.ACE2 improves liver fibrosis through autophagy WJG https://www.wjgnet.com 4976 September 7,2023 Volume 29 Issue 33 autophagy-related proteins was evaluated by multicolor immunofluorescence staining.The expression of autophagy-related indicators and AMPK pathway-related proteins was measured by western blotting.RESULTS A mouse model of liver fibrosis was successfully established after 8 wk of intraperitoneal injection of carbon tetrachloride(CCl4).rAAV2/8-ACE2 administration reduced collagen deposition and alleviated the degree of liver fibrosis in mice.The serum levels of platelet-derived growth factor,angiopoietin-2,vascular endothelial growth factor and angiotensin II were decreased,while the levels of interleukin(IL)-10 and angiotensin-(1-7)were increased in the rAAV2/8-ACE2 group.In addition,the expression of alpha-smooth muscle actin,fibronectin,and CD31 was down-regulated in the rAAV2/8-ACE2 group.TUNEL and immunofluorescence staining showed that rAAV2/8-ACE2 injection increased HSC apoptosis.Moreover,rAAV2/8-ACE2 injection notably decreased the number of autophagosomes and the expression of autophagy-related proteins(LC3I,LC3II,Beclin-1),and affected the expression of AMPK pathway-related proteins(AMPK,p-AMPK,p-mTOR).CONCLUSION ACE2 overexpression can inhibit HSC activation and promote cell apoptosis by regulating HSC autophagy through the AMPK/mTOR pathway,thereby alleviating liver fibrosis and hepatic sinusoidal remodeling.

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.

AKT regulates IL-1β-induced proliferation and activation of hepatic stellate cells

Background:Activated hepatic stellate cells(HSCs)are closely involved in the initiation,perpetuation,and resolution of liver fibrosis.Pro-inflammatory cytokine levels are positively correlated with the transition from liver injury to fibrogenesis and contribute to HSC pathophysiology in liver fibrosis.Methods:In this study,we investigated the effect of the pro-inflammatory cytokine interleukin(IL)-1βon the proliferation and signaling pathways involved in fibrogenesis in LX-2 cells,an HSC cell line,using western blotting and cell proliferation assays.Results:IL-1βincreased the proliferation rate andα-smooth muscle actin(SMA)expression of LX-2 cells in a dose-dependent manner.Within 1 h after IL-1βtreatment,c-Jun N-terminal kinase(JNK),p38,and nuclear factor-κB(NF-κB)signaling was activated in LX-2 cells.Subsequently,protein kinase B(AKT)phosphorylation and an increase inα-SMA expression were observed in LX-2 cells.Each inhibitor of JNK,p38,or NF-κB decreased cell proliferation,AKT phosphorylation,andα-SMA expression in IL-1β-treated LX-2 cells.Conclusion:These results indicate that JNK,p38,and NF-κB signals converge at AKT phosphorylation,leading to LX-2 activation by IL-1β.Therefore,the AKT signaling pathway can be used as a target for alleviating liver fibrosis by the inflammatory cytokine IL-1β.

BMI-1 activates hepatic stellate cells to promote the epithelialmesenchymal transition of colorectal cancer cells

BACKGROUND Activated hepatic stellate cells(aHSCs)are the major source of cancer-associated fibroblasts in the liver.Although the crosstalk between aHSCs and colorectal cancer(CRC)cells supports liver metastasis(LM),the mechanisms are largely unknown.AIM To explore the role of BMI-1,a polycomb group protein family member,which is highly expressed in LM,and the interaction between aHSCs and CRC cells in promoting CRC liver metastasis(CRLM).METHODS Immunohistochemistry was carried out to examine BMI-1 expression in LM and matched liver specimens of CRC.The expression levels of BMI-1 in mouse liver during CRLM(0,7,14,21,and 28 d)were detected by Western blotting(WB)and the quantitative polymerase chain reaction(qPCR)assay.We overexpressed BMI-1 in HSCs(LX2)by lentivirus infection and tested the molecular markers of aHSCs by WB,qPCR,and the immunofluorescence assay.CRC cells(HCT116 and DLD1)were cultured in HSC-conditioned medium(LX2 NC CM or LX2 BMI-1 CM).CM-induced CRC cell proliferation,migration,epithelial-mesenchymal transition(EMT)phenotype,and transforming growth factor beta(TGF-β)/SMAD pathway changes were investigated in vitro.A mouse subcutaneous xenotransplantation tumor model was established by co-implantation of HSCs(LX2 NC or LX2 BMI-1)and CRC cells to investigate the effects of HSCs on tumor growth and the EMT phenotype in vivo.RESULTS Positive of BMI-1 expression in the liver of CRLM patients was 77.8%.The expression level of BMI-1 continued to increase during CRLM in mouse liver cells.LX2 overexpressed BMI-1 was activated,accompanied by increased expression level of alpha smooth muscle actin,fibronectin,TGF-β1,matrix metalloproteinases,and interleukin 6.CRC cells cultured in BMI-1 CM exhibited enhanced proliferation and migration ability,EMT phenotype and activation of the TGF-β/SMAD pathway.In addition,the TGF-βR inhibitor SB-505124 diminished the effect of BMI-1 CM on SMAD2/3 phosphorylation in CRC cells.Furthermore,BMI-1 overexpressed LX2 HSCs promoted tumor growth and the EMT phenotype in vivo.CONCLUSION High expression of BMI-1 in liver cells is associated with CRLM progression.BMI-1 activates HSCs to secrete factors to form a prometastatic environment in the liver,and aHSCs promote proliferation,migration,and the EMT in CRC cells partially through the TGF-β/SMAD pathway.

Mechanism of annexin A1/N-formylpeptide receptor regulation of macrophage function to inhibit hepatic stellate cell activation through Wnt/β-catenin pathway

BACKGROUND Hepatic fibrosis is a common pathological process of chronic liver diseases with various causes,which can progress to cirrhosis.AIM To evaluate the effect and mechanism of action annexin(Anx)A1 in liver fibrosis and how this could be targeted therapeutically.METHODS CCl4(20%)and active N-terminal peptide of AnxA1(Ac2-26)and N-formylpeptide receptor antagonist N-Boc-Phe-Leu-Phe-Leu-Phe(Boc2)were injected intraperitoneally to induce liver fibrosis in eight wild-type mice/Anxa1 knockout mice,and to detect expression of inflammatory factors,collagen deposition,and the role of the Wnt/β-catenin pathway in hepatic fibrosis.RESULTS Compared with the control group,AnxA1,transforming growth factor(TGF)-β1,interleukin(IL)-1βand IL-6 expression in the liver of mice with hepatic fibrosis induced by CCl4 was significantly increased,which promoted collagen deposition and expression ofα-smooth muscle actin(α-SMA),collagen type I and connective tissue growth factor(CTGF),and increased progressively with time.CCl4 induced an increase in TGF-β1,IL-1βand IL-6 in liver tissue of AnxA1 knockout mice,and the degree of liver inflammation and fibrosis and expression ofα-SMA,collagen I and CTGF were significantly increased compared with in wild-type mice.After treatment with Ac2-26,expression of liver inflammatory factors,degree of collagen deposition and expression of a-SMA,collagen I and CTGF were decreased compared with before treatment.Boc2 inhibited the anti-inflammatory and antifibrotic effects of Ac2-26.AnxA1 downregulated expression of the Wnt/β-catenin pathway in CCl4-induced hepatic fibrosis.In vitro,lipopolysaccharide(LPS)induced hepatocyte and hepatic stellate cell(HSC)expression of AnxA1.Ac2-26 inhibited LPS-induced RAW264.7 cell activation and HSC proliferation,decreased expression ofα-SMA,collagen I and CTGF in HSCs,and inhibited expression of the Wnt/β-catenin pathway after HSC activation.These therapeutic effects were inhibited by Boc2.CONCLUSION AnxA1 inhibited liver fibrosis in mice,and its mechanism may be related to inhibition of HSC Wnt/β-catenin pathway activation by targeting formylpeptide receptors to regulate macrophage function.

Hydroxysafflor yellow A protects against thioacetamide-induced liver fibrosis in rats via suppressing proinflammatory/fibrogenic mediators and promoting hepatic stellate cell senescence and apoptosis

Objective:To evaluate the effect of hydroxysafflor yellow A(HSYA)on thioacetamide-induced liver fibrosis.Methods:Thioacetamide was administered to rats intraperitoneally in doses of 200 mg/kg twice a week for 12 weeks.Thioacetamide-intoxicated rats were given silymarin(50 mg/kg)or HSYA(5 mg/kg)orally every day for 8 weeks.Liver enzymes,fibrosis markers,histological changes as well as immunohistochemistry of TNF-α,IL-6,p21,α-SMA,and caspase-3 were examined.The effect of HSYA on HSC-T6 activation/proliferation and apoptosis was also determined in vitro.Results:HSYA decreased liver enzymes,TNF-α,IL-6,and p21 expressions,hepatic PDGF-B,TIMP-1,TGF-β1,and hydroxyproline levels,as well as fibrosis score(S2 vs.S4)compared to the thioacetamide group.HSYA also downregulatedα-SMA while increasing caspase-3 expression.Surprisingly,at 500μg/mL,HSYA had only a slightly suppressive effect on HSC proliferation,with a 9.5%reduction.However,it significantly reduced TGF-β1,inhibitedα-SMA expression,induced caspase-3 expression,and promoted cell senescence.Conclusions:HSYA may be a potential therapeutic agent for delaying and reversing the progression of liver fibrosis.More research on HSYA at higher doses and for a longer period is warranted.

Liver fibrosis and hepatic stellate cells: Etiology, pathological hallmarks and therapeutic targets

Liver fibrosis is a reversible wound-healing process aimed at maintaining organ integrity, and presents as the critical pre-stage of liver cirrhosis, which will eventually progress to hepatocellular carcinoma in the absence of liver transplantation. Fibrosis generally results from chronic hepatic injury caused by various factors, mainly viral infection, schistosomiasis, and alcoholism; however, the exact pathological mechanisms are still unknown. Although numerous drugs have been shown to have antifibrotic activity in vitro and in animal models, none of these drugs have been shown to be efficacious in the clinic. Importantly, hepatic stellate cells(HSCs) play a key role in the initiation, progression, and regression of liver fibrosis by secreting fibrogenic factors that encourage portal fibrocytes, fibroblasts, and bone marrow-derived myofibroblasts to produce collagen and thereby propagate fibrosis. These cells are subject to intricate cross-talk with adjacent cells, resulting in scarring and subsequent liver damage. Thus, an understanding of the molecular mechanisms of liver fibrosis and their relationships with HSCs is essential for the discovery of new therapeutic targets. This comprehensive review outlines the role of HSCs in liver fibrosis and details novel strategies to suppress HSC activity, thereby providing new insights into potential treatments for liver fibrosis.

Effects of retinoic acid on proliferation,phenotype and expression of cyclin-dependent kinase inhibitors in TGF-β1-stimulated rat hepatic stellate cells

AIM To study the molecular mechanisms ofretinoic acid(RA)on proliferation andexpression of cyclin-dependent kinase inhibitors(CKI),i.e.p16,p21 and p27 in cultured rathepatic stellate cells(HSC)stimulated withtransforming growth factor beta 1(TGF-β1).METHODS HSC were isolated from healthy ratlivers and cultured.After stimulated with1 mg/L TGF-β1,subcultured HSC were treatedwith or without 1 nmol/L RA.MTT assay,immunocytochemistry(ICC)for p16,p21,p27and α-smooth muscle actin(α-SMA)protein,insitu hybridization(ISH)for retinoic acidreceptor beta 2(RAR-β2)and p16,p21 and p27mRNA and quantitative image analysis(partially)were performed.RESULTS RA inhibited HSC proliferation(41.50%,P【0.05),decreased the protein levelof α-SMA(55.09%,P【0.05),and induced HSCto express RAR-β2 mRNA.In addition,RAincreased the protein level of p16(218.75%,P【0.05)and induced p21 protein expression;meanwhile,p27 was undetectable by ICC in bothcontrol and RA-treated HSC.However,RA hadno influence on the mRNA levels of p16,p21 orp27 as determined by ISH.CONCLISION Up-regulation of p16 and p21 on post-transcriptional level may contribule, in part to RA inhibition of TGF-β1-initiated rat HSC activation in vitro.

Hes1,an important gene for activation of hepatic stellate cells,is regulated by Notch1 and TGF-β/BMP signaling

AIM:To determine the role of Notch1 and Hes1 in regulating the activation of hepatic stellate cells(HSCs) and whether Hes1 is regulated by transforming growth factor(TGF)/bone morphogenetic protein(BMP) signaling.METHODS:Immunofluorescence staining was used to detect the expression of desmin,glial fibrillary acidic protein and the myofibroblastic marker α-smooth muscle actin(α-SMA) after freshly isolated,normal rat HSCs had been activated in culture for different numbers of days(0,1,3,7 and 10 d).The expression of α-SMA,collagen1α2(COL1α2),Notch receptors(Notch1-4),and the Notch target genes Hes1 and Hey1 were analyzed by reverse transcriptase-polymerase chain reaction.Luciferase reporter assays and Western blot were used to study the regulation of α-SMA,COL1α1,COL1α2 and Hes1 by NICD1,Hes1,CA-ALK3,and CA-ALK5 in HSC-T6 cells.Moreover,the effects of inhibiting Hes1 function in HSC-T6 cells using a Hes1 decoy were also investigated.RESULTS:The expression of Notch1 and Hes1 m RNAs was significantly down-regulated during the culture of freshly isolated HSCs.In HSC-T6 cells,Notch1 inhibited the promoter activities of α-SMA,COL1α1 and COL1α2.On the other hand,Hes1 enhanced the promoter activities of α-SMA and COL1α2,and this effect could be blocked by inhibiting Hes1 function with a Hes1 decoy.Furthermore,co-transfection of pc DNA3-CAALK3(BMP signaling activin receptor-like kinase 3) and pc DNA3.1-NICD1 further increased the expression of Hes1 compared with transfection of either vector alone in HSC-T6 cells,while pc DNA3-CA-ALK5(TGF-β signaling activin receptor-like kinase 5) reduced the effect of NICD1 on Hes1 expression.CONCLUSION:Selective interruption of Hes1 or maintenance of Hes1 at a reasonable level decreases the promoter activities of α-SMA and COL1α2,and these conditions may provide an anti-fibrotic strategy against hepatic fibrosis.

Effect of lipid on proliferation and activation of rat hepatic stellate cells(Ⅰ)

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Natural taurine promotes apoptosis of human hepatic stellate cells in proteomics analysis

AIM:To study the differential expression of proteins between natural taurine treated hepatic stellate cells and controls, and investigate the underlying regulatory mechanism of natural taurine in inhibiting hepatic fibrosis.METHODS: A proteomic strategy combining two-dimensional gel electrophoresis and ultraperform ance liquid chromatographyelectrospray ionizationtandem mass spectrometry (UPLCESIMS/MS) was used to study the differential expression of proteins and Western blotting was used to validate the results. Gene ontology (GO) method was utilized to analyze the functional enrichment of differentially expressed proteins. Flow cytometry was performed to compare the apoptosis rate between taurinetreated and untreated hepatic stellate cells (HSCs).RESULTS: Nineteen differentially expressed proteins (11 upregulated and 8 downregulated) were identifiedby 2D/MS, and the expression profiles of GLO1 and ANXA1 were validated by Western blotting. GO analysis found that these differentially expressed proteins were enriched within biological processes such as "cellular apoptosis", "oxidation reaction" and "metabolic process" in clusters. Flow cytometric analysis showed that taurinetreated HSCs had a significantly increased apoptosis rate when compared with the control group.CONCLUSION: Natural taurine can promote HSC apoptosis so as to inhibit hepatic fibrosis.

Effect of Fuzhenghuayu decoction on vascular endothelial growth factor secretion in hepatic stellate cells

Objective: To investigate the effect of Fuzhenghuayu decoction on autocrine activation of hepatic stellate cell (HSC). Methods: The drug serum containing Fuzhenghuayu decoction was collected from normal rats, and cul- tured with activated HSC in vitro. The conditioned medium from the drug serum treated HSC was added to primary cultured quiescent HSC. Cell prolifera- tion was assayed by tetrazolium colorimetric test, and the contents of type Ⅰ collagen and vascular endo- thelial growth factor (VEGF) in the supernatant were measured with ELISA. Results: The conditioned medium from activated HSC could stimulate the quiescent HSC proliferation and type Ⅰ collagen secretion. The drug serum inhibi- ted this stimulating action and VEGF secretion from the activated HSC. Conclusion: Fuzhenghuayu decoction acts effectively against the autocrine activation pathway of HSC. The mechanism may be associated with the inhibition of the secretion of VEGF by activated HSC.

Effects of Fuzhenghuayu decoction on collagen synthesis of cultured hepatic stellate cells,hepatocytes and fibroblasts in rats

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Metformin attenuates motility,contraction,and fibrogenic response of hepatic stellate cells in vivo and in vitro by activating AMP-activated protein kinase

AIM To investigate the effect of metformin on activated hepatic stellate cells(HSCs) and the possible signaling pathways involved. METHODS A fibrotic mouse model was generated by intraperitoneal injection of carbon tetrachloride(CCl_4) and subsequent treatment with or without metformin. The level of fibrosis was detected by hematoxylin-eosin staining, Sirius Red staining, and immunohistochemistry. The HSC cell line LX-2 was used for in vitro studies. The effect of metformin on cell proliferation(CCK8 assay),motility(scratch test and Transwell assay), contraction(collagen gel contraction assay), extracellular matrix(ECM) secretion(Western blot), and angiogenesis(ELISA and tube formation assay) was investigated. We also analyzed the possible signaling pathways involved by Western blot analysis.RESULTS Mice developed marked liver fibrosis after intraperitoneal injection with CCl_4 for 6 wk. Metformin decreased the activation of HSCs, reduced the deposition of ECM, and inhibited angiogenesis in CCl_4-treated mice. Platelet-derived growth factor(PDGF) promoted the fibrogenic response of HSCs in vitro, while metformin inhibited the activation, proliferation, migration, and contraction of HSCs, and reduced the secretion of ECM. Metformin decreased the expression of vascular endothelial growth factor(VEGF) in HSCs through inhibition of hypoxia inducible factor(HIF)-1α in both PDGF-BB treatment and hypoxic conditions, and it down-regulated VEGF secretion by HSCs and inhibited HSC-based angiogenesis in hypoxic conditions in vitro. The inhibitory effects of metformin on activated HSCs were mediated by inhibiting the Akt/mammalian target of rapamycin(m TOR) and extracellular signal-regulated kinase(ERK) pathways via the activation of adenosine monophosphate-activated protein kinase(AMPK).CONCLUSION Metformin attenuates the fibrogenic response of HSCs in vivo and in vitro, and may therefore be useful for the treatment of chronic liver diseases.

Anti-proliferative and pro-apoptotic effects of tectorigenin on hepatic stellate cells

AIM: To investigate the effect of tectorigenin on proliferation and apoptosis of hepatic stellate cells (HSC)-T6 cells. METHODS: HSC-T6 cells were incubated with tectorigenin at different concentrations, and their proliferation was assessed by bromodeoxyuridine incorporation assay. Apoptosis was detected by flow cytometry assay with Hoechst 33342 staining. Also, generation of reactive oxygen species (ROS), intracellular [Ca2+]i, potential of mitochondrial membrane, activities of cytochrome c and caspase-9 and-3 were investigated to explore a conceivable apoptotic pathway. RESULTS: Tectorigenin suppressed the proliferation of HSC-T6 cells and induced apoptosis of HSC-T6 cells in a time-and dose-dependent manner. Tectorigenin at the concentration of 100 μg/mL greatly inhibited the viability of HSC-T6 cells and induced the condensation of chromatin and fragmentation of nuclei. When treated for 48 h, the percentage of cell growth and apoptosis reached 46.3% ± 2.37% (P = 0.004) and 50.67% ± 3.24% (P = 0.003), respectively. Furthermore, tectorigenin-induced apoptosis of HSC-T6 cells was associated with the generation of ROS, increased intracellular [Ca2+]i, loss of mitochondrial membrane potential, translocation of cytochrome c, and activation of caspase-9 and -3. CONCLUSION: Tectorigenin inhibits proliferation of HSC-T6 cells and induces apoptosis of HSC-T6 cells.

Schistosoma japonicum egg antigen up-regulates fibrogenesis and inhibits proliferation in primary hepatic stellate cells in a concentration-dependent manner

AIM:To investigate the effects of different concentrations of Schistosoma japonicum(S.japonicum) egg antigen on fibrogenesis and apoptosis in primary hepatic stellate cells(HSCs).METHODS:A mouse model of schistosomiasis-associated liver fibrosis(SSLF) was established by infecting mice with schistosomal cercaria via the abdomen.HSCs were isolated from SSLF mice by discontinuous density gradient centrifugation,and their identity was confirmed by immunofluorescence double staining of α-smooth muscle actin(α-SMA) and desmin.The growth inhibitory effect and 50% inhibitory concentration(IC50) of S.japonicum egg antigen for primary HSCs(24 h) were determined using a cell counting kit-8(CCK-8) assay.The expression levels of α-SMA,matrix metalloproteinase-9(MMOL/LP-9) and tissue inhibitor of metalloproteinases-1(TIMP-1) in HSCs in response to different concentrations of S.japonicum egg antigen were detected by Western blotting and real-time reverse transcription-polymerase chain reaction.The levels of phospho-P38(P-P38),phospho-Jun N-terminal kinase(P-JNK) and phospho-Akt(P-AKT) in HSCs were detected by Western blotting.RESULTS:An SSLF mouse model was established,and primary HSCs were successfully isolated and cultured.S.japonicum egg antigen inhibited HSC proliferation in a concentration-dependent manner.The IC50 of the S.japonicum egg antigen was 244.53 ± 35.26 μg/mL.S.japonicum egg antigen enhanced α-SMA expression at both the mRNA and protein levels and enhanced TIMP-1 expression at the mRNA level in HSCs(P < 0.05),whereas the expression of MMOL/LP-9 was attenuated at both the mRNA and protein levels in a concentration-dependent manner(P < 0.05).A high concentration of S.japonicum egg antigen enhanced P-P38,P-JNK and P-AKT activation(P < 0.05).The changes in α-SMA and MMOL/LP-9 expression induced by S.japonicum egg antigen were closely correlated with P-P38 and P-JNK activation(P < 0.05).The attenuation of MMOL/LP-9 was also correlated with P-AKT activation(P < 0.05),but the increase in α-SMA expression was not.TIMP-1 expression was not correlated with P-P38,P-JNK or P-AKT activation.CONCLUSION:S.japonicum egg antigen promotes fibrogenesis,activates the P38/JNK mitogen-activated protein kinase and AKT/PI3K signaling pathways and inhibits proliferation in primary HSCs isolated from SSLF mice in a concentration-dependent manner.

Roles of hepatic stellate cells in acute liver failure: From the perspective of inflammation and fibrosis

Acute liver failure(ALF)usually results in hepatocellular dysfunction and coagulopathy and carries a high mortality rate.Hepatic stellate cells(HSCs)are famous for their role in liver fibrosis.Although some recent studies revealed that HSCs might participate in the pathogenesis of ALF,the accurate mechanism is still not fully understood.This review focuses on the recent advances in understanding the functions of HSCs in ALF and revealed both protective and promotive roles during the pathogenesis of ALF:HSC activation participates in the maintenance of cell attachment and the architecture of liver tissue via extracellular matrix production and assists liver regeneration by producing growth factors;and HSC inflammation plays a role in relaying inflammation signaling from sinusoids to parenchyma via secretion of inflammatory cytokines.A better understanding of roles of HSCs in the pathogenesis of ALF may lead to improvements and novel strategies for treating ALF patients.