Activation of the connective tissue growth factor (CTGF)-transforming growth factor β 1 (TGF-β 1) axis in hepatitis C virus-expressing hepatocytes

Caffeic acid ethanolamide induces antifibrosis, anti-inflammatory, and antioxidant effects protects against bleomycin-induced pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive interstitial lung disease; its cause is unknown, and it leads to notable health problems. Currently, only two drugs are recommended for IPF treatment. Although these drugs can mitigate lung function decline, neither can improve nor stabilize IPF or the symptoms perceived by patients. Therefore, the development of novel treatment options for pulmonary fibrosis is required. The present study investigated the effects of a novel compound, caffeic acid ethanolamide (CAEA), on human pulmonary fibroblasts and evaluated its potential to mitigate bleomycin-induced pulmonary fibrosis in mice. CAEA inhibited TGF-β-induced α-SMA and collagen expression in human pulmonary fibroblasts, indicating that CAEA prevents fibroblasts from differentiating into myofibroblasts following TGF-β exposure. In animal studies, CAEA treatment efficiently suppressed immune cell infiltration and the elevation of TNF-α and IL-6 in bronchoalveolar lavage fluid in mice with bleomycin-induced pulmonary fibrosis. Additionally, CAEA exerted antioxidant effects by recovering the enzymatic activities of oxidant scavengers. CAEA directly inhibited activation of TGF-β receptors and protected against bleomycin-induced pulmonary fibrosis through inhibition of the TGF-β/SMAD/CTGF signaling pathway. The protective effect of CAEA was comparable to that of pirfenidone, a clinically available drug. Our findings support the potential of CAEA as a viable method for preventing the progression of pulmonary fibrosis.

MCPIP1 Inhibits Hepatic Stellate Cell Activation in Autocrine and Paracrine Manners, Preventing Liver Fibrosis

BACKGROUND & AIMS

Hepatic fibrosis is characterized by enhanced deposition of extracellular matrix (ECM), which results from the wound healing response to chronic, repeated injury of any etiology. Upon injury, hepatic stellate cells (HSCs) activate and secrete ECM proteins, forming scar tissue, which leads to liver dysfunction. Monocyte-chemoattractant protein-induced protein 1 (MCPIP1) possesses anti-inflammatory activity, and its overexpression reduces liver injury in septic mice. In addition, mice with liver-specific deletion of Zc3h12a develop features of primary biliary cholangitis. In this study, we investigated the role of MCPIP1 in liver fibrosis and HSC activation.

METHODS

We analyzed MCPIP1 levels in patients' fibrotic livers and hepatic cells isolated from fibrotic murine livers. In vitro experiments were conducted on primary HSCs, cholangiocytes, hepatocytes, and LX-2 cells with MCPIP1 overexpression or silencing.

RESULTS

MCPIP1 levels are induced in patients' fibrotic livers compared with their nonfibrotic counterparts. Murine models of fibrosis revealed that its level is increased in HSCs and hepatocytes. Moreover, hepatocytes with Mcpip1 deletion trigger HSC activation via the release of connective tissue growth factor. Overexpression of MCPIP1 in LX-2 cells inhibits their activation through the regulation of TGFB1 expression, and this phenotype is reversed upon MCPIP1 silencing.

CONCLUSIONS

We demonstrated that MCPIP1 is induced in human fibrotic livers and regulates the activation of HSCs in both autocrine and paracrine manners. Our results indicate that MCPIP1 could have a potential role in the development of liver fibrosis.

Correction: Activation of the Connective Tissue Growth Factor (CTGF)-Transforming Growth Factor β 1 (TGF-β 1) Axis in Hepatitis C Virus-Expressing Hepatocytes

[This corrects the article DOI: 10.1371/journal.pone.0046526.].

Placental nanoparticle gene therapy normalizes gene expression changes in the fetal liver associated with fetal growth restriction in a fetal sex-specific manner

Fetal growth restriction (FGR) is associated with increased risk of developing non-communicable diseases. We have a placenta-specific nanoparticle gene therapy protocol that increases placental expression of human insulin-like growth factor 1 (hIGF1), for the treatment of FGR in utero. We aimed to characterize the effects of FGR on hepatic gluconeogenesis pathways during early stages of FGR establishment, and determine whether placental nanoparticle-mediated hIGF1 therapy treatment could resolve differences in the FGR fetus. Female Hartley guinea pigs (dams) were fed either a Control or Maternal Nutrient Restriction (MNR) diet using established protocols. At GD30-33, dams underwent ultrasound guided, transcutaneous, intraplacental injection of hIGF1 nanoparticle or PBS (sham) and were sacrificed 5 days post-injection. Fetal liver tissue was fixed and snap frozen for morphology and gene expression analysis. In female and male fetuses, liver weight as a percentage of body weight was reduced by MNR, and not changed with hIGF1 nanoparticle treatment. In female fetal livers, expression of hypoxia inducible factor 1 (Hif1α) and tumor necrosis factor (Tnfα) were increased in MNR compared to Control, but reduced in MNR + hIGF1 compared to MNR. In male fetal liver, MNR increased expression of Igf1 and decreased expression of Igf2 compared to Control. Igf1 and Igf2 expression was restored to Control levels in the MNR + hIGF1 group. This data provides further insight into the sex-specific mechanistic adaptations seen in FGR fetuses and demonstrates that disruption to fetal developmental mechanisms may be returned to normal by treatment of the placenta.

Discovery of a cryptic site at the interface 2 of TEAD - Towards a new family of YAP/TAZ-TEAD inhibitors

The Hippo pathway is involved in organ size control and tissue homeostasis by regulating cell growth, proliferation and apoptosis. It controls the phosphorylation of the transcription co-activator YAP (Yes associated protein) and TAZ (Transcriptional coactivator with PDZ-binding motif) in order to control their nuclear import and their interaction with TEAD (Transcriptional Enhanced Associated Domain). YAP, TAZ and TEADs are dysregulated in several cancers making YAP/TAZ-TEAD interaction a new emerging anti-cancer target. We report the synthesis of a set of trisubstituted pyrazoles which bind to hTEAD2 at the interface 2 revealing for the first time a cryptic pocket created by the movement of the phenol ring of Y382. Compound 6 disrupts YAP/TAZ-TEAD interaction in HEK293T cells and inhibits TEAD target genes and cell proliferation in MDA-MB-231 cells. Compound 6 is therefore the first inhibitor of YAP/TAZ-TEAD targeting interface 2. This molecule could serve with other pan-TEAD inhibitors such as interface 3 ligands, for the delineation of the relative importance of VGLL vs YAP/TAZ in a given cellular model.

The Pathogenesis of Hydrocephalus Following Aneurysmal Subarachnoid Hemorrhage

Hydrocephalus is a common complication of aneurysmal subarachnoid hemorrhage (aSAH) and reportedly contributes to poor neurological outcomes. In this review, we summarize the molecular and cellular mechanisms involved in the pathogenesis of hydrocephalus following aSAH and summarize its treatment strategies. Various mechanisms have been implicated for the development of chronic hydrocephalus following aSAH, including alterations in cerebral spinal fluid (CSF) dynamics, obstruction of the arachnoid granulations by blood products, and adhesions within the ventricular system. Regarding molecular mechanisms that cause chronic hydrocephalus following aSAH, we carried out an extensive review of animal studies and clinical trials about the transforming growth factor-β/SMAD signaling pathway, upregulation of tenascin-C, inflammation-dependent hypersecretion of CSF, systemic inflammatory response syndrome, and immune dysregulation. To identify the ideal treatment strategy, we discuss the predictive factors of shunt-dependent hydrocephalus between surgical clipping and endovascular coiling groups. The efficacy and safety of other surgical interventions including the endoscopic removal of an intraventricular hemorrhage, placement of an external ventricular drain, the use of intraventricular or cisternal fibrinolysis, and an endoscopic third ventriculostomy on shunt dependency following aSAH were also assessed. However, the optimal treatment is still controversial, and it necessitates further investigations. A better understanding of the pathogenesis of acute and chronic hydrocephalus following aSAH would facilitate the development of treatments and improve the outcome.

Molecular Crosstalk between the Hepatitis C Virus and the Extracellular Matrix in Liver Fibrogenesis and Early Carcinogenesis

Simple Summary

In the era of direct-acting antivirals against the hepatitis C virus (HCV), curing chronic hepatitis C has become a reality. However, while replicating chronically, HCV creates a peculiar state of inflammation and oxidative stress in the infected liver, which fuels DNA damage at the onset of HCV-induced hepatocellular carcinoma (HCC). This cancer, the second leading cause of death by cancer, remains of bad prognosis when diagnosed. This review aims to decipher how HCV durably alters elements of the extracellular matrix that compose the liver microenvironment, directly through its viral proteins or indirectly through the induction of cytokine secretion, thereby leading to liver fibrosis, cirrhosis, and, ultimately, HCC.

Abstract

Chronic infection by the hepatitis C virus (HCV) is a major cause of liver diseases, predisposing to fibrosis and hepatocellular carcinoma. Liver fibrosis is characterized by an overly abundant accumulation of components of the hepatic extracellular matrix, such as collagen and elastin, with consequences on the properties of this microenvironment and cancer initiation and growth. This review will provide an update on mechanistic concepts of HCV-related liver fibrosis/cirrhosis and early stages of carcinogenesis, with a dissection of the molecular details of the crosstalk during disease progression between hepatocytes, the extracellular matrix, and hepatic stellate cells.

Pathophysiology and Treatment Options for Hepatic Fibrosis: Can It Be Completely Cured?

Hepatic fibrosis is a dynamic process that occurs as a wound healing response against liver injury. During fibrosis, crosstalk between parenchymal and non-parenchymal cells, activation of different immune cells and signaling pathways, as well as a release of several inflammatory mediators take place, resulting in inflammation. Excessive inflammation drives hepatic stellate cell (HSC) activation, which then encounters various morphological and functional changes before transforming into proliferative and extracellular matrix (ECM)-producing myofibroblasts. Finally, enormous ECM accumulation interferes with hepatic function and leads to liver failure. To overcome this condition, several therapeutic approaches have been developed to inhibit inflammatory responses, HSC proliferation and activation. Preclinical studies also suggest several targets for the development of anti-fibrotic therapies; however, very few advanced to clinical trials. The pathophysiology of hepatic fibrosis is extremely complex and requires comprehensive understanding to identify effective therapeutic targets; therefore, in this review, we focus on the various cellular and molecular mechanisms associated with the pathophysiology of hepatic fibrosis and discuss potential strategies to control or reverse the fibrosis.

Strategies Targeting the Innate Immune Response for the Treatment of Hepatitis C Virus-Associated Liver Fibrosis

Direct-acting antivirals eliminate hepatitis C virus (HCV) in more than 95% of treated individuals and may abolish liver injury, arrest fibrogenesis, and reverse fibrosis and cirrhosis. However, liver regeneration is usually a slow process that is less effective in the late stages of fibrosis. What is more, fibrogenesis may prevail in patients with advanced cirrhosis, where it can progress to liver failure and hepatocellular carcinoma. Therefore, the development of antifibrotic drugs that halt and reverse fibrosis progression is urgently needed. Fibrosis occurs due to the repair process of damaged hepatic tissue, which eventually leads to scarring. The innate immune response against HCV is essential in the initiation and progression of liver fibrosis. HCV-infected hepatocytes and liver macrophages secrete proinflammatory cytokines and chemokines that promote the activation and differentiation of hepatic stellate cells (HSCs) to myofibroblasts that produce extracellular matrix (ECM) components. Prolonged ECM production by myofibroblasts due to chronic inflammation is essential to the development of fibrosis. While no antifibrotic therapy is approved to date, several drugs are being tested in phase 2 and phase 3 trials with promising results. This review discusses current state-of-the-art knowledge on treatments targeting the innate immune system to revert chronic hepatitis C-associated liver fibrosis. Agents that cause liver damage may vary (alcohol, virus infection, etc.), but fibrosis progression shows common patterns among them, including chronic inflammation and immune dysregulation, hepatocyte injury, HSC activation, and excessive ECM deposition. Therefore, mechanisms underlying these processes are promising targets for general antifibrotic therapies.

Influence of Silica Exposure for Lung Silicosis Rat

OBJECTIVE

To investigate the influence of silica exposure on the expression of connective tissue growth factor (CTGF), transforming growth factor beta-1 (TGF-β1), and platelet-derived growth factor (PDGF) in lung silicosis rat.

METHODS

Wistar rats were divided into an experimental group and a control group. In the experimental group, rats were exposed to silica by intratracheal instillation. In the control group, rats were exposed to physiological saline by intratracheal instillation. After 45 days, we compared the level of fibrosis and CTGF, TGF-β1, and PDGF in the lungs by immunohistochemistry or reverse transcription-polymerase chain reaction between the two groups.

RESULTS

The results showed that the expression levels of CTGF, TGF-β1, and PDGF mRNA were significantly higher in the experimental group than those in the control group (P < 0.05). The positive staining of CTGF, TGF-β1, and PDGF mRNA was found in the cytoplasm, especially in the silicotic nodules of the hyalinisation section and cell endochylema of the alveolar macrophages, type II pneumonocytes, and lung tracheal epithelium. There were significantly positive correlations between CTGF, TGF-β1, and PDGF expressions (P < 0.05). A protein-protein interaction analysis showed interactions between TGF-β1, CTGF, and PDGF.

CONCLUSIONS

TGF-β/CTGF signaling pathway plays an important role in silicosis. Silicon dioxide exposure can induce the expression of CTGF, TGF-β1, and PDGF.

RNAi nanotherapy for fibrosis: highly durable knockdown of CTGF/CCN-2 using siRNA-DegradaBALL (LEM-S401) to treat skin fibrotic diseases

Skin fibrosis occurs in a variety of human diseases but the current anti-fibrosis treatments are not sufficient. One major cause of fibrotic diseases shared across diverse organ fibrosis is uncontrolled overexpression of the connective tissue growth factor (CTGF, also known as CCN2). Here, we examine the anti-fibrotic activity of RNAi therapy utilizing siRNA against CTGF with a new drug delivery system (DDS), 'DegradaBALL', which is based on porous nanoparticles, for durable CTGF gene silencing. DegradaBALL is a modular DDS having many favorable properties for RNA delivery such as effective intracellular uptake, convenient drug loading, biocompatibility, sustained release profile and biodegradability. DegradaBALL loaded with siCTGF, named 'LEM-S401', showed highly durable and effective CTGF gene-silencing in TGF-β induced lung fibrosis and skin fibrosis model cells, A549 and HaCaT, respectively. In addition, LEM-S401 induced knockdown of collagen types I and III, which are excess extracellular matrix components in fibrotic skin in addition to CTGF in the mouse wound healing model. Most importantly, we showed that LEM-S401 effectively inhibited the formation of hypertrophic scars in wound-associated dermal fibrosis mouse models, during both the epidermis recovery and tissue remodeling process. Our findings suggest that LEM-S401 could be a highly potent therapeutic option for skin fibrotic diseases.

Erythropoietin Alleviates Burn-induced Muscle Wasting

Background: Burn injury induces long-term skeletal muscle pathology. We hypothesized EPO could attenuate burn-induced muscle fiber atrophy. Methods: Rats were allocated into four groups: a sham burn group, an untreated burn group subjected to third degree hind paw burn, and two burn groups treated with weekly or daily EPO for four weeks. Gastrocnemius muscle was analyzed at four weeks post-burn. Results: EPO attenuated the reduction of mean myofiber cross-sectional area post-burn and the level of the protective effect was no significant difference between two EPO-treated groups (p=0.784). Furthermore, EPO decreased the expression of atrophy-related ubiquitin ligase, atrogin-1, which was up-regulated in response to burn. Compared to untreated burn rats, those receiving weekly or daily EPO groups had less cell apoptosis by TUNEL assay. EPO decreased the expression of cleaved caspase 3 (key factor in the caspase-dependent pathway) and apoptosis-inducing factor (implicated in the caspase-independent pathway) after burn. Furthermore, EPO alleviated connective tissue overproduction following burn via transforming growth factor beta 1-Smad2/3 pathway. Daily EPO group caused significant erythrocytosis compared with untreated burn group but not weekly EPO group. Conclusion: EPO therapy attenuated skeletal muscle apoptosis and fibrosis at four weeks post-burn. Weekly EPO may be a safe and effective option in muscle wasting post-burn.

Tspan15 Is a New Stemness-Related Marker in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the second cause of cancer-related deaths worldwide. A clearer understanding of the molecular mechanisms underlying tumor growth and invasiveness remains crucial for developing new therapies. Here, the expression of tetraspanins, a family of plasma membrane organizers involved in tumor progression, has been addressed. Integrative approaches combining transcriptomics and bioinformatics allow demonstrating the induced and heterogeneous expression of Tspan15 in HCC. Tspan15 positive tumors exhibit signatures related to hepatic progenitor cells as well as recurrence of cancer. Immunohistochemistry experiments confirm Tspan15 expression in the subset of HCC expressing stemness-related markers such as EpCAM and Cytokeratin-19. Functional networks reveal that most of these genes expressed in correlation to Tspan15 support cell proliferation. Furthermore, Tspan15 overexpression in the hepatoma cell line HepG2 significantly increases cell proliferation. A quantitative proteomic analysis of the secretome reveals a higher abundance of the protein connective tissue growth factor (CTGF), a pleiotropic matricellular signaling protein. Proteomic profiling of Tspan15 complexes allows identifying numerous membrane proteins including several growth factor receptors. Finally, Tspan15 increases ERK1/2 phosphorylation that directly controls CTGF expression and secretion. In conclusion, Tspan15 is a new stemness-related marker in HCC which exhibits high potential of tumor growth and recurrence.

Supplementation with CTGF, SDF1, NGF, and HGF promotes ovine in vitro oocyte maturation and early embryo development

The strategies for improving the in vitro maturation (IVM) of domestic animal oocytes focus on promoting nuclear and cytoplasmic maturation. The identification of paracrine factors and their supplementation in the culture medium represent effective approaches for oocyte maturation and embryo development. This study investigated the effects of paracrine factor supplementation including connective tissue growth factor (CTGF), nerve growth factor (NGF), hepatocyte growth factor (HGF), and stromal derived factor 1 (SDF1) on ovine oocytes and early parthenogenetic embryos using an in vitro culture system. First, we identified the optimal concentrations of CTGF (30 ng/mL), SDF1 (10 ng/mL), NGF (3 ng/mL), and HGF (100 ng/mL) for promoting oocyte maturation, which combined, induced nuclear maturation in 94.19% of oocytes. This combination also promoted cumulus cell expansion and inhibited oocyte/cumulus apoptosis, while enabling a larger proportion (33.04%) of embryos to develop into blastocysts than in the controls and prevented embryo apoptosis. These novel findings demonstrate that the paracrine factors CTGF, SDF1, NGF, and HGF facilitate ovine oocyte and early parthenogenetic embryo development in vitro. Thus, supplementation with these factors may help optimize the IVM of ovine oocytes and early parthenogenetic embryo development strategies.

Transforming growth factor beta1 targets estrogen receptor signaling in bronchial epithelial cells

Background

Sex differences in idiopathic pulmonary fibrosis (IPF) suggest a protective role for estrogen (E2); however, mechanistic studies in animal models have produced mixed results. Reports using cell lines have investigated molecular interactions between transforming growth factor beta1 (TGF-β1) and estrogen receptor (ESR) pathways in breast, prostate, and skin cells, but no such interactions have been described in human lung cells. To address this gap in the literature, we investigated a role for E2 in modulating TGF-β1-induced signaling mechanisms and identified novel pathways impacted by estrogen in bronchial epithelial cells.

Methods

We investigated a role for E2 in modulating TGF-β1-induced epithelial to mesenchymal transition (EMT) in bronchial epithelial cells (BEAS-2Bs) and characterized the effect of TGF-β1 on ESR mRNA and protein expression in BEAS-2Bs. We also quantified mRNA expression of ESRs in lung tissue from individuals with IPF and identified potential downstream targets of E2 signaling in BEAS-2Bs using RNA-Seq and gene set enrichment analysis.

Results

E2 negligibly modulated TGF-β1-induced EMT; however, we report the novel observation that TGF-β1 repressed ESR expression, most notably estrogen receptor alpha (ESR1). Results of the RNA-Seq analysis showed that TGF-β1 and E2 inversely modulated the expression of several genes involved in processes such as extracellular matrix (ECM) turnover, airway smooth muscle cell contraction, and calcium flux regulation. We also report that E2 specifically modulated the expression of genes involved in chromatin remodeling pathways and that this regulation was absent in the presence of TGF-β1.

Conclusions

Collectively, these results suggest that E2 influences unexplored pathways that may be relevant to pulmonary disease and highlights potential roles for E2 in the lung that may contribute to sex-specific differences.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0861-5) contains supplementary material, which is available to authorized users.

Involvement of the ubiquitin-proteasome system in the expression of extracellular matrix genes in retinal pigment epithelial cells

Emerging evidence suggests that dysfunction of the ubiquitin-proteasome system is involved in the pathogenesis of numerous senile degenerative diseases including retinal disorders. The aim of this study was to assess whether there is a link between proteasome regulation and retinal pigment epithelium (RPE)-mediated expression of extracellular matrix genes. For this purpose, human retinal pigment epithelial cells (ARPE-19) were treated with different concentrations of transforming growth factor-β (TGFβ), connective tissue growth factor (CTGF), interferon-γ (IFNγ) and the irreversible proteasome inhibitor epoxomicin. First, cytotoxicity and proliferation assays were carried out. The expression of proteasome-related genes and proteins was assessed and proteasome activity was determined. Then, expression of fibrosis-associated factors fibronectin (FN), fibronectin EDA domain (FN EDA), metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinases-1 (TIMP-1) and peroxisome proliferator-associated receptor-γ (PPARγ) was assessed. The proteasome inhibitor epoxomicin strongly arrested cell cycle progression and down-regulated TGFβ gene expression, which in turn was shown to induce expression of pro-fibrogenic genes in ARPE-19 cells. Furthermore, epoxomicin induced a directional shift in the balance between MMP-2 and TIMP-1 and was associated with down-regulation of transcription of extracellular matrix genes FN and FN-EDA and up-regulation of the anti-fibrogenic factor PPARγ. In addition, both CTGF and TGFβ were shown to affect expression of proteasome-associated mRNA and protein levels. Our results suggest a link between proteasome activity and pro-fibrogenic mechanisms in the RPE, which could imply a role for proteasome-modulating agents in the treatment of retinal disorders characterized by RPE-mediated fibrogenic responses.

HBx induces expression of CTGF in the transfected hepatoma cell line HepG2

Aim: To investigate the effect of HBx on CTGF expression by hepatocytes. Materials & methods: HepG2 cells were transfected with the full-length gene of HBV, HBV protein-expressing plasmids, rhTGFβ1, LY2109761 or Smad2 siRNA, respectively, using Lipofectamine 3000. CTGF expression was detected by real-time PCR, ELISA, respectively. Then the effect of IL-32 on CTGF promoter was assayed by the Dual Luciferase® Reporter Assay System. Results: We found that HBx could induce CTGF expression by HepG2 cells in a concentration-dependent manner. CTGF expression induced by HBx employed the activation of TGFβ1-Smad2 signal pathway. Inhibition of TGFβ1 or Smad2 decreased CTGF expression induced by HBx. Conclusion: HBV might be involved in the pathogenesis of liver fibrosis through the HBx-induced CTGF expression.

Critical role of CREBH-mediated induction of transforming growth factor β2 by hepatitis C virus infection in fibrogenic responses in hepatic stellate cells

Mechanisms of hepatic fibrogenesis induced by hepatitis C virus (HCV), one of the leading causes of liver fibrosis, are not fully understood. We studied transcriptional up-regulation of transforming growth factor β (TGF-β), especially TGF-β2, which is mediated by activation of liver-enriched transcription factor cAMP-responsive element-binding protein, hepatocyte specific (CREBH) triggered by HCV infection and its functional significance for induction of profibrogenic phenotypes by interaction of HCV-infected cells with hepatic stellate cells (HSCs). Compared to TGF-β1, expression of TGF-β2 mRNA was induced faster and to a higher level upon HCV infection. Serum TGF-β2 levels in hepatitis C patients were higher compared to those in healthy individuals and were positively correlated with hepatic fibrosis stages F0-F2. TGF-β2 promoter activity was decreased and increased, respectively, by silencing and overexpression of CREBH. CREBH recognition sites were identified in the TGF-β2 promoter. CREBH binding to the promoter and its increase in cells expressing HCV Core-NS2 were shown by gel mobility shift and chromatin immunoprecipitation, respectively. The active form of CREBH was detectable in HCV-infected chimeric mice with human livers and cells expressing HCV proteins. Involvement of CREBH in HCV-induced fibrogenic response was further demonstrated in the CREBH null-mutant mouse model. Fibrogenic phenotypes were assessed using co-cultures of HCV-infected cells and HSCs. Expressions of fibrogenic factors and TGF-β1 increasing in the co-cultures was prevented by TGF-β2- or CREBH silencing.

CONCLUSION

CREBH was identified as a key positive regulator of TGF-β2 transcription in HCV-infected cells. TGF-β2 released from infected cells potentially contributes to cross-induction of TGF-β in an autocrine manner through its own signaling pathway, leading to an increase in fibrogenic responses in adjacent HSCs. (Hepatology 2017;66:1430-1443).

Angiotensin II induces connective tissue growth factor expression in human hepatic stellate cells by a transforming growth factor β-independent mechanism

Angiotensin II (Ang II) promotes hepatic fibrosis by increasing extracellular matrix (ECM) synthesis. Connective tissue growth factor (CTGF) plays a crucial role in the pathogenesis of hepatic fibrosis and emerges as downstream of the profibrogenic cytokine transforming growth factor-β (TGF-β). We aimed to investigate the molecular events that lead from the Ang II receptor to CTGF upregulation in human hepatic stellate cells, a principal fibrogenic cell type. Ang II produced an early, AT₁ receptor-dependent stimulation of CTGF expression and induced a rapid activation of PKC and its downstream p38 MAPK, thereby activating a nuclear factor-κB (NF-κB) and Smad2/3 cross-talk pathway. Chemical blockade of NF-κB and Smad2/3 signaling synergistically diminished Ang II-mediated CTGF induction and exhibited an additive effect in abrogating the ECM accumulation caused by Ang II. Furthermore, we demonstrated that CTGF expression was essential for Ang II-mediated ECM synthesis. Interestingly, the ability of dephosphorylated, but not phosphorylated JNK to activate Smad2/3 signaling revealed a novel role of JNK in Ang II-mediated CTGF overexpression. These results suggest that Ang II induces CTGF expression and ECM accumulation through a special TGF-β-independent interaction between the NF-κB and Smad2/3 signals elicited by the AT₁/PKCα/p38 MAPK pathway.

Simvastatin attenuates macrophage-mediated gemcitabine resistance of pancreatic ductal adenocarcinoma by regulating the TGF-β1/Gfi-1 axis

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with an intrinsic resistance to almost all chemotherapeutic drugs, including gemcitabine. An abundance of tumor-associated macrophages (TAMs), which can promote the resistance of PDAC to gemcitabine, has been observed in the microenvironments of several tumors. In this study, we confirmed that incubation in TAM-conditioned medium (TAM-CM) reduces the gemcitabine-induced apoptosis of PDAC cells. Simvastatin attenuated the TAM-mediated resistance of PDAC cells to gemcitabine. Further investigation found that simvastatin reversed the TAM-mediated down-regulation of Gfi-1 and up-regulation of CTGF and HMGB1. Simvastatin induced Gfi-1 expression, which increased the sensitivity of PDAC cells to gemcitabine by decreasing TGF-β1 secretion by TAMs. A luciferase reporter assay and ChIP assay revealed that Gfi-1 directly repressed the transcription of CTGF and HMGB1. Simvastatin also reversed the effects of gemcitabine on the expression of TGF-β1 and Gfi-1 and reduced the resistance of PDAC to gemcitabine in vivo. These results provide the first evidence that simvastatin attenuates the TAM-mediated gemcitabine resistance of PDAC by blocking the TGF-β1/Gfi-1 axis. These findings suggest the TGF-β1/Gfi-1 axis as a novel therapeutic target for treating PDAC.

Altered expression of the CCN genes in the lungs of mice in response to cigarette smoke exposure and viral and bacterial infections

The CCN proteins are key signaling and regulatory molecules involved in many biological functions and contribute to malignant and non-malignant lung diseases. Despite the high morbidity and mortality of the lung respiratory infectious diseases, there is very little data related to the expression of the CCNs during infection. We investigated in mice the pulmonary mRNA expression levels of five CCNs (1 to 5) in response to influenza A virus (IAV) and bacterial agents (Nontypeable Haemophilus influenzae (NTHi), lipopolysaccharide (LPS) and lipoteichoic acid (LTA)). IAV, NTHi, LPS or LTA were instilled intranasally into mice. Mice were also exposed for 4days or 8weeks to cigarette smoke alone or prior infection to IAV in order to determine if CS modifies the CCN response to a viral infection. All challenges induced a robust inflammation. The mRNA expression of CCN1, CCN2 and CCN3 was decreased after short exposure to CS whereas prolonged exposure altered the expression of CCN1, CCN3 and CCN4. Influenza A virus infection increased CCN1, 2, 4 and 5 mRNA levels but expression of CCN3 was significantly decreased. Acute CS exposure prior infection had little effect on the expression of CCN genes but prolonged exposure abolished the IAV-dependent induction. Treatment with LPS or LTA and infection with NTHi revealed that both Gram-positive and Gram-negative bacteria rapidly modulate the expression of the CCN genes. Our findings reveal that several triggers of lung inflammation influence differently the CCN genes. CCN3 deserves special attention since its mRNA expression is decreased by all the triggers studied.

The differential effects of low birth weight and Western diet consumption upon early life hepatic fibrosis development in guinea pig

Postnatal intake of an energy dense diet, the Western diet (WD), is a strong risk factor for liver fibrosis. Recently, adverse in utero conditions resulting in low birth weight (LBW) have also been associated with postnatal fibrosis development. We assessed the independent and possible synergistic effects of placental insufficiency-induced LBW and postnatal WD consumption on liver fibrosis in early adulthood, with a specific focus on changes in inflammation and apoptosis pathways in association with fibrogenesis. Male LBW (uterine artery ablation) and normal birth weight (NBW) guinea pig pups were fed either a control diet (CD) or WD from weaning to 150 days. Significant steatosis, mild lobular inflammation, apoptosis and mild stage 1 fibrosis (perisinusoidal or portal) were evident in WD-fed offspring (NBW/WD and LBW/WD). In LBW/CD versus NBW/CD offspring, increased transforming growth factor-beta 1 and matrix metallopeptidase mRNA and sma- and Mad-related protein 4 (SMAD4) were present in conjunction with minimal stage 1 portal fibrosis. Further, connective tissue growth factor mRNA was increased and miR-146a expression decreased in LBW offspring, irrespective of diet. Independent of birth weight, WD-fed offspring exhibited increased expression of fibrotic genes as well as elevated inflammatory and apoptotic markers. Moreover, the augmented expression of collagen, type III, alpha 1 and tumor necrosis factor-alpha was associated with increased recruitment of RNA polymerase II and enhanced histone acetylation (K9) to their respective promoters. These data support a role for both LBW and postnatal WD as factors contributing to hepatic fibrosis development in offspring through distinct pathways.

Changes in serum transforming growth factor-β1 levels in chronic hepatitis C patients under antiviral therapy

BACKGROUND

Several cytokines including transforming growth factor (TGF)-β1 have been suggested to be involved in the pathogenesis of fibrosis in chronic hepatitis C. We examined the changes of TGF-β1 serum levels and their predictive value in patients with chronic hepatitis C under antiviral therapy.

METHODS

We included 84 patients with chronic hepatitis C who were treated with pegylated interferon-α and ribavirin between 2008 and 2009. Treatment was given for 24-48 weeks depending on HCV genotype. Serum TGF-β1 levels were measured by an ELISA assay at baseline, at the end of therapy (EOT), and at 6 months after the EOT. Liver fibrosis was evaluated by transient elastography.

RESULTS

Of the 84 patients, 76.2% achieved sustained virological response (SVR), 8.3% responded at the EOT but relapsed during post-therapy follow up (RR) and 15.5% had no response (NR). In all patients, mean TGF-β1 levels were 16,980 pg/mL at baseline and decreased significantly at EOT (12,041 pg/mL) and at 6 months of post-treatment follow up (13,254 pg/mL) (P≤0.001). In particular, mean TGF-β1 levels decreased significantly from baseline to EOT and to six months of post-treatment follow up in patients with SVR and numerically but not significantly in patients with RR or NR. TGF-β1 levels were not associated with the severity of liver stiffness estimated by transient elastography.

CONCLUSION

Our data show that TGF-β1 serum levels decrease significantly at the EOT and remain decreased 6 months after the EOT mostly in chronic hepatitis C patients who achieve SVR after pegylated interferon-α and ribavirin combination treatment.

Role of fibrogenic and inflammatory cytokines in HCV-induced fibrosis

HCV is one of the main causative agents of liver fibrosis and hepatocellular carcinoma. Liver inflammation resulting from HCV infection triggers fibrosis. In HCV-related fibrosis, differentiated hepatic stellate cells (HSCs) known as myofibroblasts participate in the fibrogenic and inflammatory response. TGF-β1 and CTGF, released from these HSCs, have been implicated as master cytokines mediating HCV induced hepatic fibrosis. PDGF is another potent mitogen, which facilitates the progression of liver fibrosis by enhancing the proliferation and migration of HSCs. In addition to these major cytokines, the release of TNF-α, IL-6, IL-1b and IL-10 by immune cells also promotes the effect of HCV induced fibrosis. Targeting these cytokines may offer the potential for treatments to prevent or cure fibrosis.

Decorin alleviated chronic hydrocephalus via inhibiting TGF-β1/Smad/CTGF pathway after subarachnoid hemorrhage in rats

Chronic hydrocephalus is one of the severe complications after subarachnoid hemorrhage (SAH). However, there is no efficient treatment for the prevention of chronic hydrocephalus, partially due to poor understanding of underlying pathogenesis, subarachnoid fibrosis. Transforming growth factor-β1(TGF-β1) is a potent fibrogenic factor implicated in wide range of fibrotic diseases. To investigate whether decorin, a natural antagonist for TGF-β1, protects against subarachnoid fibrosis and chronic hydrocephalus after SAH, two-hemorrhage-injection SAH model was conducted in 6-week-old rats. Recombinant human decorin(rhDecorin) (30ug/2ul) was administered before blood injection and on the 10th day after SAH. TGF-β1, p-Smad2/3, connective tissue growth factor (CTGF), collagen I and pro-collagen I c-terminal propeptide were assessed via western blotting, enzyme-linked immunosorbent assay, radioimmunoassay and immunofluorescence. And neurobehavioral tests and Morris water maze were employed to evaluate long-term neurological functions after SAH. We found that SAH induced heightened activation of TGF-β1/Smad/CTGF axis, presenting as a two peak response of TGF-β1 in cerebrospinal fluid, elevation of TGF-β1, p-Smad2/3, CTGF, collagen I in brain parenchyma and pro-collagen I c-terminal propeptide in cerebrospinal fluid, and increased lateral ventricle index. rhDecorin treatment effectively inhibited up-regulation of TGF-β1, p-Smad2/3, CTGF, collagen I and pro-collagen I c-terminal propeptide after SAH. Moreover, rhDecorin treatment significantly reduced lateral ventricular index and incidence of chronic hydrocephalus after SAH. Importantly, rhDecorin improved neurocognitive deficits after SAH. In conclusion, rhDecorin suppresses extracellular matrix accumulation and following subarachnoid fibrosis via inhibiting TGF-β1/Smad/CTGF pathway, preventing development of hydrocephalus and attenuating long-term neurocognitive defects after SAH.

Decoy oligonucleotide technology in fibrosis: Application and delivery strategy

Fibrosis is a pathological condition caused by a variety of etiologies, which is characterized by an increase in the fibrous connective tissue and a reduction in the parenchymal cells of several organs and can result in structural damage and functional impairment of organs. With the development of molecular biology and cellular biology technology in recent years, gene therapy methods for fibrosis are drawing attention, including antisense oligonucleotides, RNA interference, Decoy oligonucleotide (ODN) technology and so on. Among them, Decoy ODN technology can block the target gene expression by capturing specific transcription factors, having the potential to interfere with the expression of the fibrosis related genes. This paper will review the application of Decoy ODN technology in fibrosis as well as the delivery strategy in vivo.

Small heterodimer partner attenuates profibrogenic features of hepatitis C virus-infected cells

BACKGROUND & AIMS

An atypical orphan nuclear receptor small heterodimer partner (SHP) is known to be regulated by AMP-activated protein kinase (AMPK). Both of them inhibit TGF-β and Smad signalling and exhibit antifibrotic activity in the liver. However, little is known about the protective effects of SHP and AMPK against hepatitis c virus (HCV)-induced hepatic fibrosis.

METHODS

Levels of SHP, p-AMPK and fibrotic markers in HCV-infected human liver and in Huh-7.5 cells infected with HCV genotype 2a (JFH-1) were investigated. The effect of adenovirus-mediated overexpression of SHP (Ad-SHP) and AMPK activation via metformin and 5-amino-1-b-D-ribofuranosyl-imidazole-4-carboxamide (AICAR) on fibrotic gene expression was evaluated in HCV-infected cells. Finally, we examined the effect of Ad-SHP and AMPK activators on invasion and activation of LX2 human HSCs induced by conditioned media from HCV-infected hepatocyte (CM).

RESULTS

In HCV-infected human livers and Huh-7.5 cells infected with HCV, SHP mRNA and protein levels were diminished compared with controls, whereas profibrotic factors were increased. Pharmacological AMPK activation recovered SHP expression, and Ad-SHP inhibited HCV-induced fibrotic gene expression. This finding was accompanied by inhibition of HCV-stimulated nuclear factor-kappa B, an inducer of TGF-β. Moreover, CytoSelect invasion assay revealed that enhanced activity and invasiveness of hepatic stellate cells induced by CM.

CONCLUSION

These results demonstrate that overexpression of SHP and activation of AMPK reverses profibrogenic features of HCV-infected cells by decreasing TGF-β and fibrotic gene expression. These findings provide a rationale for SHP as a possible therapeutic target against HCV-induced hepatic fibrosis.

Blockade of CCN4 attenuates CCl4-induced liver fibrosis

INTRODUCTION

CCN4, also termed WNT-inducible signaling pathway protein-1 (WISP-1), has important roles in inflammation and tissue injury. This study aimed to investigate the effect of CCN4 inhibition using monoclonal anti-CCN4 antibody (CCN4mAb) on the liver injury and fibrosis in a mouse model of liver fibrosis.

MATERIAL AND METHODS

The mouse liver fibrosis model was induced by carbon tetrachloride (CCl4). Mice received vehicle (saline/olive oil) by subcutaneous injection, CCl4 by subcutaneous injection or CCl4 (subcutaneous) plus CCN4mAb by subcutaneous injection. The pro-inflammatory and pro-fibrotic factors were determined by Western blot. The biochemistry and histopathology, collagen deposition and nuclear factor (NF)-κB activity were also assessed.

RESULTS

Chronic CCl4 treatment caused liver injury and collagen accumulation. The expression levels of CCN4, pro-inflammatory and pro-fibrotic mediators as well as the activity of NF-κB were markedly increased. Treatment with CCN4mAb significantly inhibited CCl4-induced CCN4 expression, leading to attenuated CCl4-induced liver injury and the inflammatory response. CCN4 blockade also significantly reduced the formation of collagen in the liver and the expression of α-smooth muscle actin and transforming growth factor β1.

CONCLUSIONS

CCN4 inhibition by CCN4mAb in vivo significantly attenuated the CCl4-induced liver injury and the progression of liver fibrosis. CCN4 may represent a novel therapeutic target for liver injury and fibrosis.

Relationship between microRNAs and signaling pathways associated with hepatic stellate cells

Activation and transdifferentiation of hepatic stellate cells (HSCs) caused by a variety of signal transduction pathways triggered by inflammatory factors and cytokines are a key initiating event in the process of hepatic fibrosis. MicroRNAs (miRNAs) existing in a wide variety of organisms play a role by negative regulation of their target genes at the transcriptional or translational level. Research shows that several signal transduction pathways associated with HSCs can regulate miRNA transcription, processing, maturation and function. At the same time, different miRNAs also regulate HSC activation, proliferation and apoptosis-related signal transduction. This interaction can provide some ideas for the molecular target therapy of hepatic fibrosis and the exploration of its pathogenesis.

HCV core-mediated activation of latent TGF-β via thrombospondin drives the crosstalk between hepatocytes and stromal environment

BACKGROUND & AIMS

The mechanisms by which fibrosis, cirrhosis, and hepatocellular carcinoma (HCC) develop during chronic hepatitis C virus (HCV) infection are not fully understood. We previously observed that HCV core protein induced a TGF-β-dependent epithelial mesenchymal transition, a process contributing to the promotion of cell invasion and metastasis by impacting TGF-β1 signalling. Here we investigated HCV core capacity to drive increased expression of the active form of TGF-β1n transgenic mice and hepatoma cell lines.

METHODS

We used an in vivo model of HCV core expressing transgenic mice.

RESULTS

We observed that about 50% of genes deregulated by core protein expression were TGF-β1 target genes. Active TGF-β levels were increased in HCV core transgenic mouse livers. Overexpression of core protein in hepatoma cells increased active TGF-β levels in culture supernatants and induced Smad2/3 phosphorylation, thus reflecting activation of the TGF-β signaling pathway. Moreover, our data showed the implication of thrombospondin-1 in core-dependent TGF-β activation. Finally, hepatoma cells expressing HCV core could activate stellate cells in co-culture and this activation was TGF-β dependent.

CONCLUSIONS

Collectively, these data delineate a novel paradigm where HCV may be related to liver pathogenesis through its ability to induce a local, intrahepatic TGF-β activation. They argue for a dual impact of HCV core on liver fibrosis and liver carcinogenesis: HCV core could act both as autocrine and paracrine factor modulating TGF-β responses within hepatocytes and in stromal environment through TGF-β activation.

Transforming growth factor β induces expression of connective tissue growth factor in hepatic progenitor cells through Smad independent signaling

Hepatic progenitor cells (HPCs) are activated in the chronic liver injury and are found to participate in the progression of liver fibrosis, while the precise role of HPCs in liver fibrosis remains largely elusive. In this study, by immunostaining of human liver sections, we confirmed that HPCs were activated in the cirrhotic liver and secreted transforming growth factor β (TGF-β) and connective tissue growth factor (CTGF), both of which were important inducers of liver fibrosis. Besides, we used HPC cell lines LE/6 and WB-F344 as in vitro models and found that TGF-β induced secretion of CTGF in HPCs. Moreover, TGF-β signaling was intracrine activated and contributed to autonomous secretion of CTGF in HPCs. Furthermore, we found that TGF-β induced expression of CTGF was not mediated by TGF-β activated Smad signaling but mediated by TGF-β activated Erk, JNK and p38 MAPK signaling. Taken together, our results provide evidence for the role of HPCs in liver fibrosis and suggest that the production of CTGF by TGF-β activated MAPK signaling in HPCs may be a therapeutic target of liver fibrosis.