Pathway In Hepatic Stellate Cells Research Articles

Opposing regulation of the STING pathway in hepatic stellate cells by NBR1 and p62 determines the progression of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) emerges from chronic inflammation, to which activation of hepatic stellate cells (HSCs) contributes by shaping a pro-tumorigenic microenvironment. Key to this process is p62, whose inactivation leads to enhanced hepatocarcinogenesis. Here, we show that p62 activates the interferon (IFN) cascade by promoting STING ubiquitination by tripartite motif protein 32 (TRIM32) in HSCs. p62, binding neighbor of BRCA1 gene 1 (NBR1) and STING, triggers the IFN cascade by displacing NBR1, which normally prevents the interaction of TRIM32 with STING and its subsequent activation. Furthermore, NBR1 also antagonizes STING by promoting its trafficking to the endosome-lysosomal compartment for degradation independent of autophagy. Of functional relevance, NBR1 deletion completely reverts the tumor-promoting function of p62-deficient HSCs by rescuing the inhibited STING-IFN pathway, thus enhancing anti-tumor responses mediated by CD8+ Tcells. Therefore, NBR1 emerges as a synthetic vulnerability of p62 deficiency in HSCs by promoting the STING/IFN pathway, which boosts anti-tumor CD8+ Tcell responses to restrain HCC progression.

AHCC inhibited hepatic stellate cells activation by regulation of cytoglobin induction via TLR2-SAPK/JNK pathway and collagen production via TLR4-NF-κβ pathway.

Cirrhosis, which represents the end stage of liver fibrosis, remains a life-threatening condition without effective treatment. Therefore, prevention of the progression of liver fibrosis through lifestyle habits such as diet and exercise is crucial. The functional food AHCC, a standardized extract of cultured Lentinula edodes mycelia produced by Amino Up Co., Ltd. (Sapporo, Japan)] has been reported to be effective in improving the pathophysiology of various liver diseases. In this study, the aim was to analyze the influence of AHCC on hepatic stellate cells, which are responsible for liver fibrosis. Eight-week-old male C57BL6/j mice were induced with liver fibrosis by intraperitoneal injection of carbon tetrachloride. Simultaneously, they were orally administered 3% AHCC to investigate its impact on the progression of liver fibrosis. Using the human hepatic stellate cell (HHSteC) line, we analyzed the influence of AHCC on the expression of molecules related to hepatic stellate cell activation. The administration of AHCC resulted in reduced expression of collagen1a, α smooth muscle actin (αSMA), and heat shock protein 47 in the liver. Furthermore, the expression of cytoglobin, a marker for quiescent hepatic stellate cells, was enhanced. In vitro study, it was confirmed that AHCC inhibited αSMA by inducing cytoglobin via upregulating the stress-activated protein kinase/Jun NH2-terminal kinase (SAPK/JNK) pathway through Toll-like receptor (TLR) 2. In addition, AHCC suppressed collagen1a production by hepatic stellate cells through TLR4-NF-κβ pathway. AHCC was suggested to suppress hepatic fibrosis by inhibition of hepatic stellate cells activation. Daily intake of AHCC from mild fibrotic stages may have the potential to prevent the progression of liver fibrosis.NEW & NOTEWORTHY AHCC, a standardized extract of cultured Lentinula edodes mycelia, suppresses liver fibrosis progression by induction of cytoglobin via the Toll-like receptor 2 (TLR2)-stress-activated protein kinase/Jun NH2-terminal kinase (SAPK/JNK) pathway and the inhibition of collagen production via the TLR4-NFκβ pathway in hepatic stellate cells. Daily oral administration of AHCC from the stage of MASLD may have the potential to prevent disease progression to MASH with fibrosis.

Exogenous S1P via S1P receptor 2 induces CTGF expression through Src-RhoA-ROCK-YAP pathway in hepatic stellate cells.

Hepatic fibrosis, a prevalent chronic liver condition, involves excessive extracellular matrix production associated with aberrant wound healing. Hepatic stellate cells (HSCs) play a pivotal role in liver fibrosis, activated by inflammatory factors such as sphingosine 1-phosphate (S1P). Despite S1P's involvement in fibrosis, its specific role and downstream pathway in HSCs remain controversial. In this study, we investigated the regulatory role of S1P/S1P receptor (S1PR) in Hippo-YAP activation in both LX-2 cell lines and primary HSCs. Real-time PCR, western blot, pharmacological inhibitors, siRNAs, and Rho activity assays were adopted to address the molecular mechanisms of S1P mediated YAP activation. Serum and exogenous S1P significantly increased the expression of YAP target genes in HSCs. Pharmacologic inhibitors and siRNA-mediated knockdowns of S1P receptors showed S1P receptor 2 (S1PR2) as the primary mediator for S1P-induced CTGF expression in HSCs. Results using siRNA-mediated knockdown, Verteporfin, and Phospho-Tag immunoblots showed that S1P-S1PR2 signaling effectively suppressed the Hippo kinases cascade, thereby activating YAP. Furthermore, S1P increased RhoA activities in cells and ROCK inhibitors effectively blocked CTGF induction. Cytoskeletal-perturbing reagents were shown to greatly modulate CTGF induction, suggesting the important role of actin cytoskeleton in S1P-induced YAP activation. Exogeneous S1P treatment was enough to increase the expression of COL1A1 and α-SMA, that were blocked by YAP specific inhibitor. Our data demonstrate that S1P/S1PR2-Src-RhoA-ROCK axis leads to Hippo-YAP activation, resulting in the up-regulation of CTGF, COL1A1 and α-SMA expression in HSCs. Therefore, S1PR2 may represent a potential therapeutic target for hepatic fibrosis.

Analysis of core functional components in Yinchenhao Decoction and their pathways for treating liver fibrosis

To analyze the core functional component groups (CFCG) in Yinchenhao Decoction (YCHD) and their possible pathways for treating hepatic fibrosis based on network pharmacology. PPI data were extracted from DisGeNET, Genecards, CMGRN and PTHGRN to construct a weighted network using Cytoscape 3.9.1. The data of the chemical components in YCHD were obtained from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), and the potential active components and targets were selected using PreADMET Web server and SwissTargetPrediction. A fusion model was constructed to obtain the functional effect space and evaluate the effective proteins to identify the CFCG followed by GO and KEGG pathway enrichment analyses for all the targets. In cultured human hepatic stellate cells (LX-2 cells), the cytotoxicity of different compounds in YCHD was tested using CCK-8 assay; the effects of these compounds on collagen α1 (Col1a1) mRNA expression and the pathways in 20 ng/mL TGF-β1-stimulated cells were analyzed using RT-qPCR and Western blotting. A total of 1005 pathogenic genes, 226 potential active components and 1529 potential targets in YCHD and 52 potential targets of CFCG were obtained. Benzyl acetate, vanillic acid, clorius, polydatin, lauric acid and ferulic acid were selected for CCK-8 verification, and they all showed minimal cytotoxicity below the concentration of 200 μmol/L. Clorius, polydatin, lauric acid and ferulic acid all effectively inhibited TGF-β1-induced LX-2 cell activation. At the concentration of 200 μmol/L, all these 4 components inhibited PI3K, p-PI3K, AKT, p-AKT, ERK, p-ERK, P38 MAPK and p-P38 MAPK expressions in TGF-β1-induced LX-2 cells. The therapeutic effect of YCHD on hepatic fibrosis is probably mediated by its core functional components including benzyl acetate, vanillic acid, clorius, polydatin, lauric acid and ferulic acid, which inhibit the PI3K-AKT and MAPK pathways in hepatic stellate cells.

Oxidative stress promotes liver fibrosis by modulating the microRNA-144 and SIN3A-p38 pathways in hepatic stellate cells.

Background & Aims: Reactive oxygen species (ROS) act as modulators triggering cellular dysfunctions and organ damage including liver fibrosis in which hepatic stellate cell (HSC) activation plays a key role. Previous studies suggest that microRNA-144 (miR-144) acts as a pro-oxidant molecule; however, whether and how miR-144 affects HSC activation and liver fibrosis remain unknown. Methods: Carbon tetrachloride (CCl4) and bile duct ligation (BDL)-induced experimental liver fibrosis models were used. Hepatic miR-144 expression was analyzed by miRNA in situ hybridization with RNAscope probe. The in vivo effects of silencing or overexpressing miR-144 were examined with an adeno-associated virus 6 (AAV6) carrying miR-144 inhibitor or mimics in fibrotic mouse experimental models. Results: In this study, we demonstrated that ROS treatment significantly upregulated miR-144 in HSCs, which further promoted HSC activation in vitro. Interestingly, miR-144 was preferentially elevated in HSCs of experimental liver fibrosis in mice and in human liver fibrotic tissues. Furthermore, in vivo loss or gain-of-function experiments via AAV6 carrying miR-144 antagomir or agomir revealed that blockade of miR-144 in HSCs mitigated, while overexpression of miR-144 in HSCs accelerated the development of experimental liver fibrosis. Mechanistically, SIN3 transcription regulator family member A (SIN3A), a transcriptional repressor, was identified to be the target of miR-144 in HSCs. MiR-144 downregulated Sin3A, and in line with this result, specific knockdown of Sin3a in HSCs remarkedly activated p38 MAPK signaling pathway to promote HSC activation, eventually exacerbating liver fibrosis. Conclusions: Oxidative stress-driven miR-144 fuels HSC activation and liver fibrogenesis by limiting the SIN3A-p38 axis. Thus, a specific inhibition of miR-144 in HSCs could be a novel therapeutic strategy for the treatment of liver fibrosis.

Corylin Attenuates CCl4-Induced Liver Fibrosis in Mice by Regulating the GAS6/AXL Signaling Pathway in Hepatic Stellate Cells.

Liver fibrosis is reversible when treated in its early stages and when liver inflammatory factors are inhibited. Limited studies have investigated the therapeutic effects of corylin, a flavonoid extracted from Psoralea corylifolia L. (Fabaceae), on liver fibrosis. Therefore, we evaluated the anti-inflammatory activity of corylin and investigated its efficacy and mechanism of action in ameliorating liver fibrosis. Corylin significantly inhibited inflammatory responses by inhibiting the activation of mitogen-activated protein kinase signaling pathways and the expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha in human THP-1 and mouse RAW264.7 macrophages. Furthermore, corylin inhibited the expression of growth arrest-specific gene 6 in human hepatic stellate cells (HSCs) and the activation of the downstream phosphoinositide 3-kinase/protein kinase B pathway. This inhibited the activation of HSCs and the expression of extracellular matrix proteins, including α-smooth muscle actin and type I collagen. Additionally, corylin induced caspase 9 and caspase 3 activation, which promoted apoptosis in HSCs. Moreover, in vivo experiments confirmed the regulatory effects of corylin on these proteins, and corylin alleviated the symptoms of carbon tetrachloride-induced liver fibrosis in mice. These findings revealed that corylin has anti-inflammatory activity and inhibits HSC activation; thus, it presents as a potential adjuvant in the treatment of liver fibrosis.

SGLT2 inhibitor empagliflozin downregulates miRNA-34a-5p and targets GREM2 to inactivate hepatic stellate cells and ameliorate non-alcoholic fatty liver disease-associated fibrosis.

Activation of hepatic stellate cells (HSCs), the central event of fibrosis, indicates the severe stage of non-alcoholic fatty liver disease (NAFLD). MicroRNAs (miRNAs) participate in this process. Treatment with a sodium-glucose cotransporter 2 inhibitor (SGLT2i) alleviates liver fibrosis in patients with type 2 diabetes and NAFLD; however, the role of SGLT2i in ameliorating liver fibrosis in NAFLD by regulating miRNAs remains unclear. We monitored the expression of NAFLD-associated miRNAs in the livers of two NAFLD models and observed high expression of miR-34a-5p. miR-34a-5p was highly expressed in mouse primary liver non-parenchymal cells and LX-2 HSCs, and this miRNA was positively correlated with alanine transaminase levels in NAFLD models. Overexpression of miR-34a-5p enhanced LX-2 activation, whereas its inhibition prevented HSCs activation by regulating the TGFβ signaling pathway. The SGLT2i empagliflozin significantly downregulated miR-34a-5p, inhibited the TGFβ signaling pathway, and ameliorated hepatic fibrosis in NAFLD models. Subsequently, GREM2 was identified as a direct target of miR-34a-5p through database prediction and a dual-luciferase reporter assay. In LX-2 HSCs, the miR-34a-5p mimic and inhibitor directly downregulated and upregulated GREM2, respectively. Overexpressing GREM2 inactivated the TGFβ pathway whereas GREM2 knockdown activated it. Additionally, empagliflozin upregulated Grem2 expression in NAFLD models. In methionine- and choline-deficient diet-fed ob/ob mice, a fibrosis model, empagliflozin downregulated miR-34a-5p and upregulated Grem2 to improve liver fibrosis. Empagliflozin ameliorates NAFLD-associated fibrosis by downregulating miR-34a-5p and targeting GREM2 to inhibit the TGFβ pathway in HSCs.

MicroRNA-29a-3p prevents Schistosoma japonicum-induced liver fibrosis by targeting Roundabout homolog 1 in hepatic stellate cells

BackgroundSchistosomiasis is a serious but neglected parasitic disease in humans that may lead to liver fibrosis and death. Activated hepatic stellate cells (HSCs) are the principal effectors that promote the accumulation of extracellular matrix (ECM) proteins during hepatic fibrosis. Aberrant microRNA-29 expression is involved in the development of fibrotic diseases. However, less is known about the role of miR-29 in Schistosoma japonicum (S. japonicum)-induced hepatic fibrosis.MethodsThe levels of microRNA-29a-3p (miR-29a-3p) and Roundabout homolog 1 (Robo1) were examined in liver tissues during S. japonicum infection. The possible involvement of the miR-29a-3p-Robo1 signaling pathway was determined. We used MIR29A conditional knock-in mice and mice injected with an miR-29a-3p agomir to investigate the role of miR-29a-3p in schistosomiasis-induced hepatic fibrosis. The functional contributions of miR-29a-3p-Robo1 signaling in liver fibrosis and HSC activation were investigated using primary mouse HSCs and the human HSC cell line LX-2.ResultsMiR-29a-3p was downregulated in humans and mice with schistosome-induced fibrosis, and Robo1 was upregulated in liver tissues. The miR-29a-3p targeted Robo1 and negatively regulated its expression. Additionally, the expression level of miR-29a-3p in schistosomiasis patients was highly correlated with the portal vein and spleen thickness diameter, which represent the severity of fibrosis. Furthermore, we demonstrated that efficient and sustained elevation of miR-29a-3p reversed schistosome-induced hepatic fibrosis. Notably, we showed that miR-29a-3p targeted Robo1 in HSCs to prevent the activation of HSCs during infection.ConclusionsOur results provide experimental and clinical evidence that the miR-29a-3p-Robo1 signaling pathway in HSCs plays an important role in the development of hepatic fibrosis. Therefore, our study highlights the potential of miR-29a-3p as a therapeutic intervention for schistosomiasis and other fibrotic diseases.Graphical

Site-specific ubiquitination of VDAC1 restricts its oligomerization and mitochondrial DNA release in liver fibrosis

Mitochondrial DNA (mtDNA) released through protein oligomers, such as voltage-dependent anion channel 1 (VDAC1), triggers innate immune activation and thus contributes to liver fibrosis. Here, we investigated the role of Parkin, an important regulator of mitochondria, and its regulation of VDAC1-mediated mtDNA release in liver fibrosis. The circulating mitochondrial DNA (mtDNA) and protein levels of liver Parkin and VDAC1 were upregulated in patients with liver fibrosis. A 4-week CCl4 challenge induced release of mtDNA, activation of STING signaling, a decline in autophagy, and apoptosis in mouse livers, and the knockout of Parkin aggravated these effects. In addition, Parkin reduced mtDNA release and prevented VDAC1 oligomerization in a manner dependent on its E3 activity in hepatocytes. We found that site-specific ubiquitination of VDAC1 at lysine 53 by Parkin interrupted VDAC1 oligomerization and prevented mtDNA release into the cytoplasm under stress. The ubiquitination-defective VDAC1 K53R mutant predominantly formed oligomers that resisted suppression by Parkin. Hepatocytes expressing VDAC1 K53R exhibited mtDNA release and thus activated the STING signaling pathway in hepatic stellate cells, and this effect could not be abolished by Parkin. We propose that the ubiquitination of VDAC1 at a specific site by Parkin confers protection against liver fibrosis by interrupting VDAC1 oligomerization and mtDNA release.

12-O-tetradecanoylphorbol-13-acetate Reduces Activation of Hepatic Stellate Cells by Inhibiting the Hippo Pathway Transcriptional Coactivator YAP

Although protein kinase C (PKC) regulates various biological activities, including cell proliferation, differentiation, migration, tissue remodeling, gene expression, and cell death, the antifibrotic effect of PKC in myofibroblasts is not fully understood. We investigated whether 12-O-tetradecanoylphorbol-13-acetate (TPA), a PKC activator, reduced the activation of hepatic stellate cells (HSCs) and explored the involvement of the Hippo pathway transcriptional coactivator YAP. We analyzed the effect of TPA on the proliferation and expression of α-smooth muscle actin (SMA) in the LX-2 HSC line. We also analyzed the phosphorylation of the Hippo pathway molecules YAP and LATS1 and investigated YAP nuclear translocation. We examined whether Gö 6983, a pan-PKC inhibitor, restored the TPA-inhibited activities of HSCs. Administration of TPA decreased the growth rate of LX-2 cells and inhibited the expression of α-SMA and collagen type I alpha 1 (COL1A1). In addition, TPA induced phosphorylation of PKCδ, LATS1, and YAP and inhibited the nuclear translocation of YAP compared with the control. These TPA-induced phenomena were mostly ameliorated by Gö 6983. Our results indicate that PKCδ exerts an antifibrotic effect by inhibiting the Hippo pathway in HSCs. Therefore, PKCδ and YAP can be used as therapeutic targets for the treatment of fibrotic diseases.

Targeting FAPα-expressing hepatic stellate cells overcomes resistance to antiangiogenics in colorectal cancer liver metastasis models.

Vessel co-option has been demonstrated to mediate colorectal cancer liver metastasis (CRCLM) resistance to antiangiogenic therapy. The current mechanisms underlying vessel co-option have mainly focused on “hijacker” tumor cells, whereas the function of the “hijackee” sinusoidal blood vessels has not been explored. Here, we found that the occurrence of vessel co-option in bevacizumab-resistant CRCLM xenografts was associated with increased expression of fibroblast activation protein α (FAPα) in the co-opted hepatic stellate cells (HSCs), which was dramatically attenuated in HSC-specific conditional Fap-knockout mice bearing CRCLM allografts. Mechanistically, bevacizumab treatment induced hypoxia to upregulate the expression of fibroblast growth factor–binding protein 1 (FGFBP1) in tumor cells. Gain- or loss-of-function experiments revealed that the bevacizumab-resistant tumor cell–derived FGFBP1 induced FAPα expression by enhancing the paracrine FGF2/FGFR1/ERK1/-2/EGR1 signaling pathway in HSCs. FAPα promoted CXCL5 secretion in HSCs, which activated CXCR2 to promote the epithelial-mesenchymal transition of tumor cells and the recruitment of myeloid-derived suppressor cells. These findings were further validated in tumor tissues derived from patients with CRCLM. Targeting FAPα+ HSCs effectively disrupted the co-opted sinusoidal blood vessels and overcame bevacizumab resistance. Our study highlights the role of FAPα+ HSCs in vessel co-option and provides an effective strategy to overcome the vessel co-option–mediated bevacizumab resistance.

Bone marrow mesenchymal stem cells inhibit hepatic fibrosis via the AABR07028795.2/rno-miR-667-5p axis

BackgroundThe mechanism of bone marrow mesenchymal stem cells (BMSCs) in treating hepatic fibrosis remains unclear.MethodsTGF-β1-induced hepatic stellate cell (HSC)-T6 and CCl4-induced hepatic fibrosis rats were treated with BMSCs. HSC-T6 cell activity was determined using the cell counting kit-8 assay, and the histology change was evaluated using hematoxylin and eosin and Masson staining. The expression of fibrosis markers was determined using real-time quantitative PCR, Western blotting, and immunocytochemistry. RNA sequencing (RNA-seq) was used to screen the lncRNAs involved in the effect of BMSCs in fibrosis, and the function of fibrosis-associated lncRNA in fibrosis histology change and fibrosis marker expression was investigated. The potential miRNA target of lncRNA was predicted using R software. The interaction between lncRNA and miRNA was verified using luciferase report system and RNA immunoprecipitation (RIP) in 293T and HSC-T6 cells.ResultsBMSC attenuated TGF-β1-induced HSC-T6 activation and suppressed the expression of fibrosis-associated gene (MMP2, Collagen I, and αSMA) expression at the transcription and translation levels. BMSC treatment also improves hepatic fibrosis in rats with CCl4-induced fibrosis by decreasing the expression of fibrosis-associated genes and suppressing collagen deposition in the liver. RNA-seq revealed that AABR07028795.2 (lnc-BIHAA1) was downregulated in the TGF-β1-induced HSC-T6 after treatment with BMSCs as compared with those in TGF-β1-induced HSC-T6, and subsequently, functional analysis showed that lnc-BIHAA1 plays a beneficial role in suppressing hepatic fibrosis. Luciferase activity assay and RIP revealed that lnc-BIHAA1 interacted with the miRNA, rno-miR-667-5p, functioning as a fibrosis phenotype suppressor in TGF-β1-induced HSC-T6. Moreover, overexpression of rno-miR-667-5p significantly reverses the effect of lnc-BIHAA1 on HSC-T6.ConclusionsBMSC treatment suppresses hepatic fibrosis by downregulating the lnc-BIHAA1/rno-miR-667-5p signaling pathway in HSCs. Our results provide a scientific basis for establishing BMSCs as a biological treatment method for liver fibrosis.

Naringenin is a Potential Immunomodulator for Inhibiting Liver Fibrosis by Inhibiting the cGAS-STING Pathway.

Naringenin is an anti-inflammatory flavonoid that has been studied in chronic liver disease. The mechanism specific to its antifibrosis activity needs further investigation This study was to focused on the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) pathway in hepatic stellate cells and clarified the antifibrosis mechanism of naringenin. The relationship between the cGAS-stimulator of interferon genes (STING) pathway and liver fibrosis was analyzed using the Gene Expression Omnibus database. Histopathology, immunohistochemistry, fluorescence staining, Western blotting and polymerase chain reaction were performed to assess gene and protein expression levels associated with the cGAS pathway in clinical liver tissue samples and mouse livers. Molecular docking was performed to evaluate the relationship between naringenin and cGAS, and western blotting was performed to study the expression of inflammatory factors downstream of cGAS in vitro. Clinical database analyses showed that the cGAS-STING pathway is involved in the occurrence of chronic liver disease. Naringenin ameliorated liver injury and liver fibrosis, decreased collagen deposition and cGAS expression, and inhibited inflammation in carbon tetrachloride (CCl4)-treated mice. Molecular docking found that cGAS may be a direct target of naringenin. Consistent with the in vivo results, we verified the inhibitory effect of naringenin on activated hepatic stellate cells (HSCs). By using the cGAS-specific agonist double-stranded (ds)DNA, we showed that naringenin attenuated the activation of cGAS and its inflammatory factors affected by dsDNA. We verified that naringenin inhibited the cGAS-STING pathway, thereby reducing the secretion of inflammatory factors by HSCs to ameliorate liver fibrosis. Interrupting the cGAS-STING pathway helped reverse the fibrosis process. Naringenin has potential as an antihepatic fibrosis drug.

Inonotsuoxide B suppresses hepatic stellate cell activation and proliferation via the PI3K/AKT and ERK1/2 pathway

Hepatic stellate cells (HSCs) serve a pivotal role in the formation and degradation of the extracellular matrix during liver fibrosis. Inonotsuoxide B is a tetracyclic triterpenoid that can be extracted from Inonotus obliquus and has been previously reported to inhibit the growth of liver and gastric cancer cells. However, its effect on liver fibrosis remain poorly understood. Therefore, in the present study, the potential antiproliferative effects of inonotsuoxide B on HSCs was investigated. Initially, cells were divided into the following five groups: Control; platelet-derived growth factor (PDGF)-BB (10 ng/ml); and PDGF-BB + inonotsuoxide B (5, 10 and 20 µg/ml) groups. Inonotsuoxide B treatment (5, 10 and 20 µg/ml) was revealed to reverse PDGF-BB-induced HSC proliferation. Furthermore, the protein expression of α-smooth-muscle actin (α-SMA) and type I collagen was significantly decreased in the inonotsuoxide B (10 and 20 µg/ml) groups compared with the PDGF-BB group. Inonotsuoxide B (5, 10 and 20 µg/ml) was also revealed to suppress PDGF-BB-induced α-SMA mRNA expression and activation of the PI3K/AKT and ERK signaling pathways in HSCs. These findings suggest that inonotsuoxide B suppresses the proliferation and activation of HSCs by inhibiting the PI3K/AKT and ERK1/2 signaling pathways.

Prostaglandin E2 and Receptors: Insight Into Tumorigenesis, Tumor Progression, and Treatment of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a common primary liver cancer with ∼750,000 annual incidence rates globally. PGE2, usually known as a pro-inflammatory cytokine, is over-expressed in various human malignancies including HCC. PGE2 binds to EP receptors in HCC cells to influence tumorigenesis or enhance tumor progression through multiple pathways such as EP1-PKC-MAPK, EP2-PKA-GSK3β, and EP4-PKA-CREB. In the progression of hepatocellular carcinoma, PGE2 can promote the proliferation and migration of liver cancer cells by affecting hepatocytes directly and the tumor microenvironment (TME) through ERK/COX-2/PGE2 signal pathway in hepatic stellate cells (HSC). For the treatment of hepatocellular carcinoma, there are drugs such as T7 peptide and EP1 antagonist ONO-8711 targeting Cox-2/PGE2 axis to inhibit tumor progression. In conclusion, PGE2 has been shown to be a traditional target with pleiotropic effects in tumorigenesis and progression of HCC that could be used to develop a new potential clinical impact. For the treatment study focusing on the COX-PGE2 axis, the exclusive usage of non-steroidal anti-inflammatory agents (NSAIDs) or COX-2-inhibitors may be replaced by a combination of selective EP antagonists and traditional anti-tumoral drugs to alleviate severe side effects and achieve better outcomes.

Transforming growth factor beta-1 upregulates glucose transporter 1 and glycolysis through canonical and noncanonical pathways in hepatic stellate cells.

BACKGROUNDHepatic stellate cells (HSCs) are the key effector cells mediating the occurrence and development of liver fibrosis, while aerobic glycolysis is an important metabolic characteristic of HSC activation. Transforming growth factor-β1 (TGF-β1) induces aerobic glycolysis and is a driving factor for metabolic reprogramming. The occurrence of glycolysis depends on a high glucose uptake level. Glucose transporter 1 (GLUT1) is the most widely distributed glucose transporter in the body and mainly participates in the regulation of carbohydrate metabolism, thus affecting cell proliferation and growth. However, little is known about the relationship between TGF-β1 and GLUT1 in the process of liver fibrosis and the molecular mechanism underlying the promotion of aerobic glycolysis in HSCs.AIMTo investigate the mechanisms of action of GLUT1, TGF-β1 and aerobic glycolysis in the process of HSC activation during liver fibrosis.METHODSImmunohistochemical staining and immunofluorescence assays were used to examine GLUT1 expression in fibrotic liver tissue. A Seahorse extracellular flux (XF) analyzer was used to examine changes in aerobic glycolytic flux, lactate production levels and glucose consumption levels in HSCs upon TGF-β1 stimulation. The mechanism by which TGF-β1 induces GLUT1 protein expression in HSCs was further explored by inhibiting/promoting the TGF-β1/mothers-against-decapentaplegic-homolog 2/3 (Smad2/3) signaling pathway and inhibiting the p38 and phosphoinositide 3-kinase (PI3K)/AKT signaling pathways. In addition, GLUT1 expression was silenced to observe changes in the growth and proliferation of HSCs. Finally, a GLUT1 inhibitor was used to verify the in vivo effects of GLUT1 on a mouse model of liver fibrosis.RESULTSGLUT1 protein expression was increased in both mouse and human fibrotic liver tissues. In addition, immunofluorescence staining revealed colocalization of GLUT1 and alpha-smooth muscle actin proteins, indicating that GLUT1 expression was related to the development of liver fibrosis. TGF-β1 caused an increase in aerobic glycolysis in HSCs and induced GLUT1 expression in HSCs by activating the Smad, p38 MAPK and P13K/AKT signaling pathways. The p38 MAPK and Smad pathways synergistically affected the induction of GLUT1 expression. GLUT1 inhibition eliminated the effect of TGF-β1 on HSC proliferation and migration. A GLUT1 inhibitor was administered in a mouse model of liver fibrosis, and GLUT1 inhibition reduced the degree of liver inflammation and liver fibrosis.CONCLUSIONTGF-β1 induces GLUT1 expression in HSCs, a process related to liver fibrosis progression. In vitro experiments revealed that TGF-β1-induced GLUT1 expression might be one of the mechanisms mediating the metabolic reprogramming of HSCs. In addition, in vivo experiments also indicated that the GLUT1 protein promotes the occurrence and development of liver fibrosis.

N6-methyladenosine modification regulates ferroptosis through autophagy signaling pathway in hepatic stellate cells

Ferroptosis is a recently identified non-apoptotic form of cell death characterized by iron-dependent lipid peroxidation. However, the underlying exact mechanisms remain poorly understood. Here, we report that the total levels of N6-methyladenosine (m6A) modification are evidently increased upon exposure to ferroptosis-inducing compounds due to the upregulation of methylase METTL4 and the downregulation of demethylase FTO. Interestingly, RNA-seq shows that m6A modification appears to trigger autophagy activation by stabilizing BECN1 mRNA, which may be the potential mechanism for m6A modification-enhanced HSC ferroptosis. Importantly, YTHDF1 is identified as a key m6A reader protein for BECN1 mRNA stability, and knockdown of YTHDF1 could prevent BECN1 plasmid-induced HSC ferroptosis. Noteworthy, YTHDF1 promotes BECN1 mRNA stability and autophagy activation via recognizing the m6A binding site within BECN1 coding regions. In mice, erastin treatment alleviates liver fibrosis by inducing HSC ferroptosis. HSC-specific inhibition of m6A modification could impair erastin-induced HSC ferroptosis in murine liver fibrosis. Moreover, we retrospectively analyzed the effect of sorafenib on HSC ferroptosis and m6A modification in advanced fibrotic patients with hepatocellular carcinoma (HCC) receiving sorafenib monotherapy. Attractively, the m6A modification upregulation, autophagy activation, and ferroptosis induction occur in human HSCs. Overall, these findings reveal novel signaling pathways and molecular mechanisms of ferroptosis, and also identify m6A modification-dependent ferroptosis as a potential target for the treatment of liver fibrosis.

The Combination of Schisandrol B and Wedelolactone Synergistically Reverses Hepatic Fibrosis Via Modulating Multiple Signaling Pathways in Mice.

Hepatic fibrosis represents an important event in the progression of chronic liver injury to cirrhosis, and is characterized by excessive extracellular matrix proteins aggregation. Early fibrosis can be reversed by inhibiting hepatocyte injury, inflammation, or hepatic stellate cells activation, so the development of antifibrotic drugs is important to reduce the incidence of hepatic cirrhosis or even hepatic carcinoma. Here we demonstrate that Schisandrol B (SolB), one of the major active constituents of traditional hepato-protective Chinese medicine, Schisandra sphenanthera, significantly protects against hepatocyte injury, while Wedelolactone (WeD) suppresses the TGF-β1/Smads signaling pathway in hepatic stellate cells (HSCs) and inflammation, the combination of the two reverses hepatic fibrosis in mice and the inhibitory effect of the combination on hepatic fibrosis is superior to that of SolB or WeD treatment alone. Combined pharmacotherapy represents a promising strategy for the prevention and treatment of liver fibrosis.

Up-regulation of FUT8 inhibits TGF-β1-induced activation of hepatic stellate cells during liver fibrogenesis.

Liver fibrosis is a continuous wound healing response caused by chronic liver injury, and the activation of hepatic stellate cells (HSCs) is considered as the main event for it. Core fucosylation catalyzed by FUT8 refers to adding the fucosyl moiety to the innermost GlcNAc residue of N-linked oligosaccharides and is involved in many biological processes such as cell differentiation, migration, and signaling transduction. Aberrant core fucosylation is associated with a variety of diseases including cardiovascular disease, tumors and neuroinflammation, but much less is understood in liver fibrosis. Herein, we reported FUT8 mRNA level was increased in patients with liver fibrosis from GEO database and positively correlated with fibrosis progression. FUT8 expression and the core fucosylation were also elevated in TAA-induced mouse liver fibrosis model, and were mainly distributed in the fibrous septum of mouse liver. TGF-β1, as the most pro-fibrogenic cytokine, could promote the expression of FUT8 and total core fucosylation levels in HSCs in vitro. However, up-regulation of FUT8 in turn inhibited TGF-β1-induced trans-differentiation, migration and pro-fibrogenic signaling pathways in HSCs. In conclusion, our results suggest that the up-regulation of FUT8 inhibits TGF-β1-induced HSC activation in a negative feedback loop, and provide potential new therapeutic strategy for liver fibrosis by targeting FUT8.

Berberine Alleviates Liver Fibrosis Through Inducing Ferrous Redox to Activate ROS-Mediated Hepatic Stellate Cells Ferroptosis

Background: Berberine (BBR) has been explored as a potential anti-liverfibrosis gent, but the underlying mechanisms are little known and controversial. Here, we aimed to investigate the molecular mechanisms underlying the effect of BBR against liver fibrogenesis. Methods: Liver fibrosis was induced in mice, besides injected i.p. with TAA orCCl4, mice in treatment group received BBR intragastrically. Concurrently, combined with the TAA and BBR treatment, mice in inhibitor group were injected i.p. with Ferrostatin-1. The hepatic stellate cells (HSCs) were alsoused in the study. Findings: BBR obviously alleviated mouse liver fibrosis and restored mouse liver function, however, the pharmacological effects of BBR on against liver fibrosis significantly diminished by Ferrostatin-1 treatment. Mechanisms, BBR impaired the autophagy-lysosome pathway and increased HSCs reactive oxygen species (ROS) production, which could accelerate the breakdown of the iron-storage protein ferritin and speed up iron releasing from ferritin, resulting in the raising of the HSCs redox-active iron accumulation, triggering Fenton’s reaction, leading to the lipid peroxidation and glutathione depletion, promoting HSCs ferroptosis and attenuating liver fibrosis. Further, BBR-mediated ferritin proteolysis to raise cellular ferrous overlade via the ubiquitin-proteasome pathway in HSCs and ignited HSCs ferroptosis. Interpretation: BBR alleviated liver fibrosis through inducing ferrous redox to activate ROS-mediated HSCs ferroptosis. Our findings may be exploited clinically to provide a potential novel therapeutic strategy for liver fibrosis. Fundings: This work was supported by grants from the National Natural Science Foundation of China (82070574, U1501224), the Natural Science Foundation Team Project of Guangdong Province (2018B03031200). Declaration of Interest: The authors declare no conflict of interest. Ethical Approval: All animal studies were approved by Institutional Animal Care and Use Committee at the Sun Yat-Sen University.