TGF-β1 up-regulates the expression of PDGF-β receptor mRNA and induces a delayed PI3K-, AKT-, and p70(S6K) -dependent proliferative response in activated hepatic stellate cells

Ferulic acid ameliorates concanavalin A-induced hepatic fibrosis in mice via suppressing TGF-β/smad signaling

BACKGROUND AND AIM

Hepatic fibrosis, one of the main reasons for death globally, is a serious complication of chronic liver disorders. However, the available therapies for liver fibrosis are limited, ineffective, and often associated with adverse events. Hence, seeking for a novel, effective therapy is warranted. Our objective was to investigate the potential efficacy of ferulic acid (FA), a phenolic phytochemical, at different doses in hindering the progress of concanavalin A (Con A)-induced hepatic fibrosis and explore the involved mechanisms.

METHODS

Thirty-six mice were assorted into 6 groups (n = 6): Group I (control); group II received FA (20 mg/kg/day orally for 4 weeks); group III received Con A (6 mg/kg/week/i.v.) for 4 weeks; groups IV, V, and VI received Con A and were offered FA at 5, 10, and 20 mg/kg/day, respectively.

RESULTS

The data showed the palliative effect of FA against Con A-induced fibrosis in a dose-dependent manner. This was obvious from the recovery of liver markers and hepatic architecture with the regression of fibrosis in FA-treated mice. FA abolished Con A-mediated oxidative insults and promoted the antioxidant enzyme activities, which run through the Nrf2/HO-1 signaling. Additionally, FA suppressed Con A-induced increase in NF-kB and IL-β levels, and TNF-α immune-expression. The anti-fibrotic effect of FA was evident from the drop in TGF-β, smad3 levels, α-SMA expression, and hydroxyproline content.

CONCLUSION

FA attenuated Con A-induced liver fibrosis through stimulating Nrf2 signaling, suppressing NF-kB, and inhibiting the TGF-β/smad3 signaling pathway. Thus FA can be considered as a promising therapy for combating liver fibrosis.

Arbidol attenuates liver fibrosis and activation of hepatic stellate cells by blocking TGF-β1 signaling

Chronic liver diseases (CLD) impact over 800 million people globally, causing about 2 million deaths annually. Arbidol (ARB), an indole-derivative used to treat influenza virus infection, was extensively used during COVID-19 pandemic in China. In recent years, studies have shown that ARB, compared to other antiviral drugs, exhibits greater liver-protective efficacy, indicating a potential hepatoprotective effect beyond its antiviral activity. However, the mechanism remains unclear. In this study, we investigated the impact of ARB on liver injury/fibrosis in bile duct ligated (BDL) mice and its effect on spontaneous and transforming growth factor β1 (TGF-β1)-induced activation of primary cultured hepatic stellate cells (HSCs). Oral administration of ARB significantly ameliorated BDL-induced liver injury/fibrosis as reflected by decreased serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), reduced collagen deposition, and diminished mRNA expression of fibrosis markers. ARB notably inhibited spontaneous and TGF-β1-induced activation of primary cultured HSCs. Moreover, ARB also drastically attenuated mRNA expression levels of platelet-derived growth factor receptor (Pdgfr), transforming growth factor-beta receptor (Tgfbr) 1, Tgfbr2, matrix metalloproteinase (Mmp)-2, and Mmp-9 in activated HSCs. We further demonstrate that ARB mitigated Smad2/3 phosphorylation in both TGF-β1 treated HSCs and BDL mice. These data together demonstrate that the therapeutic efficacy of ARB on liver fibrosis is independent of its antiviral activity and likely is achieved by blocking TGF-β1 signaling-mediated HSC activation.

Bromodomain protein 4 is a key molecular driver of TGFβ1-induced hepatic stellate cell activation

Liver fibrosis is characterized by the excessive deposition of extracellular matrix in liver. Chronic liver injury induces the activation of hepatic stellate cell (HSCs), a key step in liver fibrogenesis. The activated HSC is the primary source of ECM and contributes significantly to liver fibrosis. TGFβ1 is the most potent pro-fibrotic cytokine. Bromodomain protein 4 (BrD4), an epigenetic reader of histone acetylation marks, was crucial for profibrotic gene expression in HSCs. The present study aimed to investigate the roles of BRD4 in TGFβ1-dependent HSC activation and liver fibrosis, focusing on TGFβ1-induced alterations of the levels of the fibrotic-related important proteins in HSCs by employing the heterozygous TGFβ1 knockout mice and BrD4 knockdown in vivo and in vitro. Results revealed that BrD4 protein level was significantly upregulated by TGFβ1 and BrD4 knockdown reduced TGFβ1-induced HSC activation and liver fibrosis. BrD4 was required for the influences of TGFβ1 on PDGFβ receptor and on the pathways of Smad3, Stat3, and Akt. BrD4 also mediated TGFβ1-induced increases in histone acetyltransferase p300, the pivotal pro-inflammatory NFkB p65, and tissue inhibitor of metalloproteinase 1 whereas BrD4 reduced Caspase-3 protein levels in HSCs during liver injury, independent of TGFβ1. Further experiments indicated the interaction between TGFβ1-induced BrD4 and NFkB p65 in HSCs and in liver of TAA-induced liver injury. Human cirrhotic livers were demonstrated a parallel increase in the protein levels of BrD4 and NFkB p65 in HSCs. This study revealed that BrD4 was a key molecular driver of TGFβ1-induced HSC activation and liver fibrosis.

Salvianolic acid B inhibits hepatic stellate cell activation and liver fibrosis by targeting PDGFRβ

Liver fibrosis is a reversible pathological process and a wound healing response to liver injury. As an early stage of various liver diseases, liver fibrosis can develop into cirrhosis, liver failure, and even liver cancer if not controlled in time. Salvia miltiorrhiza is a medicinal plant with hepatoprotective effects. Salvianolic acid B (Sal B) is the representative component of S. miltiorrhiza. Many studies have reported the anti-liver fibrosis effects and mechanisms of Sal B. However, the direct anti-fibrotic targets of Sal B have not yet been reported. Platelet-derived growth factor receptor β (PDGFRβ) is one of the most classical targets in liver fibrosis, which is closely related to hepatic stellate cells (HSCs) activated. Previously, we established and applied a PDGFRβ affinity chromatography model, and found that Sal B binds well to PDGFRβ. Therefore, this study aimed to investigate the direct targets of Sal B against liver fibrosis. We confirmed the binding ability of Sal B to PDGFRβ by molecular docking and a surface plasmon resonance biosensor. Our findings indicated that Sal B targeted PDGFRβ to inhibit the activation, migration and proliferation of HSCs and suppressed the PDGF-BB-induced PDGFRβ signaling pathway. Annexin V-FITC/PI assay showed that Sal B reversed the PDGF-BB-induced decrease in HSC apoptosis rate. In the mouse liver fibrosis model, Sal B inhibited the PDGFRβ signaling pathway, HSC activation and reduced inflammatory response, ultimately improved CCl4-induced liver fibrosis. In summary, the direct anti-fibrotic targets of Sal B may be PDGFRβ, and this study clarified the anti-liver fibrosis effects and mechanism of Sal B.

Ongoing involvers and promising therapeutic targets of hepatic fibrosis: The hepatic immune microenvironment

Hepatic fibrosis is often secondary to chronic inflammatory liver injury. During the development of hepatic fibrosis, the damaged hepatocytes and activated hepatic stellate cells (HSCs) caused by the pathogenic injury could secrete a variety of cytokines and chemokines, which will chemotactic innate and adaptive immune cells of liver tissue and peripheral circulation infiltrating into the injury site, mediating the immune response against injury and promoting tissue reparation. However, the continuous release of persistent injurious stimulus-induced inflammatory cytokines will promote HSCs-mediated fibrous tissue hyperproliferation and excessive repair, which will cause hepatic fibrosis development and progression to cirrhosis even liver cancer. And the activated HSCs can secrete various cytokines and chemokines, which directly interact with immune cells and actively participate in liver disease progression. Therefore, analyzing the changes in local immune homeostasis caused by immune response under different pathological states will greatly enrich our understanding of liver diseases' reversal, chronicity, progression, and even deterioration of liver cancer. In this review, we summarized the critical components of the hepatic immune microenvironment (HIME), different sub-type immune cells, and their released cytokines, according to their effect on the development of progression of hepatic fibrosis. And we also reviewed and analyzed the specific changes and the related mechanisms of the immune microenvironment in different chronic liver diseases.Moreover, we retrospectively analyzed whether the progression of hepatic fibrosis could be alleviated by modulating the HIME.We aimed to elucidate the pathogenesis of hepatic fibrosis and provide the possibility for exploring the therapeutic targets for hepatic fibrosis.

Early-immediate gene Egr1 is associated with TGFβ1 regulation of epigenetic reader Bromodomain-containing protein 4 via the canonical Smad3 signaling in hepatic stellate cells in vitro and in vivo

Upon chronic damage to the liver, multiple cytokines stimulate hepatic stellate cells (HSCs), causing the alterations of gene expression profiles and thus leading to HSC activation, a key step in liver fibrogenesis. Activated HSCs are the dominant contributors to liver fibrosis. Bromodomain containing protein 4 (BrD4), an important epigenetic reader, was demonstrated to concentrate on hundreds of enhancers associated with genes involved in multiple profibrotic pathways, thereby directing HSC activation and the fibrotic responses. The present studies were designed to examine the effect of transforming growth factor beta-1 (TGFβ1), the most potent pro-fibrotic cytokine, on BrD4 expression in HSCs and, if so, elucidated the underlying mechanisms in vitro and in vivo. The experiments employed the heterogeneous TGFβ1 knockout (TGFβ1^+/- ) mice, gene knockdown in vivo, and a model of thioacetamide (TAA)-induced liver injury. The results revealed that TGFβ1 enhanced BrD4 expression in HSCs, which was mediated, at least, by Smad3 signaling and early-immediate gene Egr1 (early growth response-1). TGFβ1-induced Smad3 signaling increased Egr1 expression and promoted Egr1 binding to BrD4 promoter at a site around -111 bp, promoting BrD4 expression. Egr1 knockdown reduced BrD4 expression in HSCs in a mouse model of TAA-induced liver injury and lessened liver fibrosis. Double fluorescence staining demonstrated a strong increase in BrD4 expression in activated HSCs in fibrotic areas of the human livers, paralleling the upregulation of p-Smad3 and Egr1. This research suggested novel molecular events underlying the roles of the master pro-fibrotic cytokine TGFβ1 in HSC activation and liver fibrogenesis.

In situ synthesis and unidirectional insertion of membrane proteins in liposome-immobilized silica stationary phase for rapid preparation of microaffinity chromatography

Cell membrane affinity chromatography has been widely applied in membrane protein (MP)-targeted drug screening and interaction analysis. However, in current methods, the MP sources are derived from cell lines or recombinant protein expression, which are time-consuming for cell culture or purification, and also difficult to ensure the purity and consistent orientation of MPs in the chromatographic stationary phase. In this study, a novel in situ synthesis membrane protein affinity chromatography (iSMAC) method was developed utilizing cell-free protein expression (CFE) and covalent immobilized affinity chromatography, which achieved efficient in situ synthesis and unidirectional insertion of MPs into liposomes in the stationary phase. The advantages of iSMAC are: 1) There is no need to culture cells or prepare recombinant proteins; 2) Specific and purified MPs with stable and controllable content can be obtained within 2 h; 3) MPs maintain the transmembrane structure and a consistent orientation in the chromatographic stationary phase; 4) The flexible and personalized construction of cDNAs makes it possible to analyze drug binding sites. iSMAC was successfully applied to screen PDGFRβ inhibitors from Salvia miltiorrhiza and Schisandra chinensis. Micro columns prepared by in-situ synthesis maintain satisfactory analysis activity within 72 h. Two new PDGFRβ inhibitors, salvianolic acid B and gomisin D, were screened out with K_D values of 13.44 and 7.39 μmol/L, respectively. In vitro experiments confirmed that the two compounds decreased α-SMA and collagen Ӏ mRNA levels raised by TGF-β in HSC-T6 cells through regulating the phosphorylation of p38, AKT and ERK. In vivo, Sal B could also attenuate CCl₄-induced liver fibrosis by downregulating PDGFRβ downstream related protein levels. The iSMAC method can be applied to other general MPs, and provides a practical approach for the rapid preparation of MP-immobilized or other biological solid-phase materials.

Metformin versus Silymarin as Hepatoprotective Agents in Mice Fibrotic Model Caused by Carbon Tetrachloride

OBJECTIVES

To study metformin hepatoprotective effects compared to silymarin on hepatic fibrosis caused by carbon tetrachloride (CCl4) in mice.

MATERIAL AND METHODS

liver fibrosis in mice was achieved by intraperitoneal injection of 2 ml/kg of CCl4 dilution in olive oil [1:9 (v/v)] twice a week for 7 weeks followed by oral treatment with metformin (250 mg/kg/day) or silymarin (100 mg/kg/day) (a standard hepatoprotective drug). The changes that follow liver fibrosis were assessed by measurement of hepatic enzymes (ALT, AST and ALP), histopathological examination using hematoxylin and eosin stain, special stains, and α-smooth muscle actin (α-SMA) immunostaining, measuring oxidative stress markers (MDA, GSH, NOx and MnSOD) and transforming growth factor-beta 1 (TGF-β1) in liver.

RESULTS

liver fibrosis was obviously developed in mice after intraperitoneal injection with CCl4 for 7 weeks. Both silymarin and metformin treatment exhibited a significant decrease in the fibrotic changes and similarly an increase in endogenous antioxidants. Interestingly there is a significant difference between silymarin and metformin regarding both efficacy and potency.

CONCLUSION

These findings highlight the anti-inflammatory, antioxidant and antifibrotic effects of metformin in CCl4-induced hepatic fibrosis in mice, but silymarin is more beneficial.

Comprehensive Analysis of the Transcriptome-Wide m6A Methylation Modification Difference in Liver Fibrosis Mice by High-Throughput m6A Sequencing

N6-Methyladenosine (m6A), a unique and common mRNA modification method in eukaryotes, is involved in the occurrence and development of many diseases. Liver fibrosis (LF) is a common response to chronic liver injury and may lead to cirrhosis and even liver cancer. However, the involvement of m6A methylation in the development of LF is still unknown. In this study, we performed a systematic evaluation of hepatic genome-wide m6A modification and mRNA expression by m6A-seq and RNA-seq using LF mice. There were 3,315 genes with significant differential m6A levels, of which 2,498 were hypermethylated and 817 hypomethylated. GO and KEGG analyses illustrated that differentially expressed m6A genes were closely correlated with processes such as the endoplasmic reticulum stress response, PPAR signaling pathway and TGF-β signaling pathway. Moreover, a total of 90 genes had both a significant change in the m6A level and mRNA expression shown by joint analysis of m6A-seq and RNA-seq. Hence, the critical elements of m6A modification, including methyltransferase WTAP, demethylases ALKBH5 and binding proteins YTHDF1 were confirmed by RT-qPCR and Western blot. In an additional cell experiment, we also observed that the decreased expression of WTAP induced the development of LF as a result of promoting hepatic stellate cell (HSC) activation. Therefore, this study revealed unique differential m6A methylation patterns in LF mice and suggested that m6A methylation was associated with the occurrence and course of LF to some extent.

Anti-fibrotic activity of sitagliptin against concanavalin A-induced hepatic fibrosis. Role of Nrf2 activation/NF-κB inhibition

Sitagliptin is known for its anti-diabetic activity though it has other pleiotropic pharmacological actions. Its effect against concanavalin A (Con A)-induced hepatic fibrosis has not been investigated yet. Our target was to test whether sitagliptin can suppress the development of Con A-induced hepatic fibrosis and if so, what are the mechanisms involved? Con A (6 mg/kg) was injected once weekly to male Swiss albino mice for four weeks. Sitagliptin was daily administered concurrently with Con A. Results have shown the potent hepatoprotective activity of sitagliptin against Con A-induced hepatitis and fibrosis. That was evident through the amelioration of hepatotoxicity serum parameters (ALT, AST, ALP, and LDH) and the increase in the level of serum albumin in sitagliptin treated mice. Simultaneously, there was amendment of the Con A-induced hepatic lesions and repression of fibrosis in sitagliptin-treated animals. Hydroxyproline, collagen content and the immuno-expression of the fibrotic markers, TGF-β and α-SMA were depressed upon sitagliptin treatment. Sitagliptin suppressed Con A-induced oxidative stress and increased antioxidants. RT-PCR analysis showed enhancement of mRNA expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its target genes (GCLc, GCLm, NQO-1, HO-1) by sitagliptin. Furthermore, sitagliptin ameliorated the level and immuno-expression of nuclear factor kappa-B (NF-κB) alongside the immuno-expression of the inflammatory cytokine, TNF-α. Taken together, this study demonstrates the hepatoprotective activity of sitagliptin which may be in part related to enhancement of Nrf2 signaling pathway and inhibition of NF-κB which interact inflammatory response in liver. Sitagliptin might be a new candidate to suppress hepatitis-associated fibrosis.

Vanillic Acid and Non-Alcoholic Fatty Liver Disease: A Focus on AMPK in Adipose and Liver Tissues

Non-alcoholic fatty liver disease (NAFLD), a growing health issue around the world, is defined as the presence of steatosis in the liver without any other detectable byproducts such as alcohol consumption which includes a wide spectrum of pathologies, such as steatohepatitis, cirrhosis, and hepatocellular carcinoma. A growing body of evidence indicates that the reduction in the 5' adenosine monophosphate-activated protein kinase (AMPK) activity, which could be activated by the consumption of the drugs, hormones, cytokines, and dietary restriction, is related to some metabolic disorders such as obesity, diabetes, PCOS, and NAFLD. Vanillic acid (VA), as an anti-inflammatory, anti-oxidative, anti-angiogenic and anti-metastatic factor, has protective effects on the liver as in two animal models of liver damage. It reduces serum levels of transaminases, inflammatory cytokines, and the accumulation of collagen in the liver and prevents liver fibrosis. Besides, it decreases body and adipose tissue weight in a mice model of obesity and, similar to the liver tissue, diminishes adipogenesis through the activation of AMPK. It has been reported that VA can target almost all of the metabolic abnormalities of NAFLD, such as hepatic steatosis, inflammation, and hepatic injury, at least partially through the activation of AMPK. Therefore, in this review, we will discuss the possible and hypothetical roles of VA in NAFLD, with a special focus on AMPK.

Lipid based nanocarriers for effective drug delivery and treatment of diabetes associated liver fibrosis

Non-alcoholic fatty liver disease (NAFLD) is a cluster of several liver diseases like hepatic steatosis, non-alcoholic steatohepatitis (NASH), non-alcoholic fatty liver (NAFL), liver fibrosis, and cirrhosis which may eventually progress to liver carcinoma. One of the primary key factors associated with the development and pathogenesis of NAFLD is diabetes mellitus. The present review emphasizes on diabetes-associated development of liver fibrosis and its treatment using different lipid nanoparticles such as stable nucleic acid lipid nanoparticles, liposomes, solid lipid nanoparticles, nanostructured lipid carriers, self-nanoemulsifying drug delivery systems, and conjugates including phospholipid, fatty acid and steroid-based. We have comprehensively described the various pathological and molecular events linking effects of elevated free fatty acid levels, insulin resistance, and diabetes with the pathogenesis of liver fibrosis. Various passive and active targeting strategies explored for targeting hepatic stellate cells, a key target in liver fibrosis, have also been discussed in detail in this review.

TGF beta -1, -2 and -3 in the modulation of fibrosis in the cornea and other organs

The TGF beta-1, -2 and -3 isoforms are transcribed from different genes but bind to the same receptors and signal through the same canonical and non-canonical signal transduction pathways. There are numerous regulatory mechanisms controlling the action of each isoform that include the organ-specific cells producing latent TGF beta growth factors, multiple effectors that activate the isoforms, ECM-associated SLRPs and basement membrane components that modulate the activity and localization of the isoforms, other interactive cytokine-growth factor receptor systems, such as PDGF and CTGF, TGF beta receptor expression on target cells, including myofibroblast precursors, receptor binding competition, positive and negative signal transduction effectors, and transcription and translational regulatory mechanisms. While there has long been the view that TGF beta-1and TGF beta-2 are pro-fibrotic, while TGF beta-3 is anti-fibrotic, this review suggests that view is too simplistic, at least in adult tissues, since TGF beta-3 shares far more similarities in its modulation of fibrotic gene expression with TGF beta-1 and TGF beta-2, than it does differences, and often the differences are subtle. Rather, TGF beta-3 should be seen as a fibro-modulatory partner to the other two isoforms that modulates a nuanced and better controlled response to injury. The complex interplay between the three isoforms and numerous interactive proteins, in the context of the cellular milieu, controls regenerative non-fibrotic vs. fibrotic healing in a response to injury in a particular organ, as well as the resolution of fibrosis, when that occurs.

Dairy consumption and hepatocellular carcinoma risk

This review provides epidemiological and translational evidence for milk and dairy intake as critical risk factors in the pathogenesis of hepatocellular carcinoma (HCC). Large epidemiological studies in the United States and Europe identified total dairy, milk and butter intake with the exception of yogurt as independent risk factors of HCC. Enhanced activity of mechanistic target of rapamycin complex 1 (mTORC1) is a hallmark of HCC promoted by hepatitis B virus (HBV) and hepatitis C virus (HCV). mTORC1 is also activated by milk protein-induced synthesis of hepatic insulin-like growth factor 1 (IGF-1) and branched-chain amino acids (BCAAs), abundant constituents of milk proteins. Over the last decades, annual milk protein-derived BCAA intake increased 3 to 5 times in Western countries. In synergy with HBV- and HCV-induced secretion of hepatocyte-derived exosomes enriched in microRNA-21 (miR-21) and miR-155, exosomes of pasteurized milk as well deliver these oncogenic miRs to the human liver. Thus, milk exosomes operate in a comparable fashion to HBV- or HCV- induced exosomes. Milk-derived miRs synergistically enhance IGF-1-AKT-mTORC1 signaling and promote mTORC1-dependent translation, a meaningful mechanism during the postnatal growth phase, but a long-term adverse effect promoting the development of HCC. Both, dietary BCAA abundance combined with oncogenic milk exosome exposure persistently overstimulate hepatic mTORC1. Chronic alcohol consumption as well as type 2 diabetes mellitus (T2DM), two HCC-related conditions, increase BCAA plasma levels. In HCC, mTORC1 is further hyperactivated due to RAB1 mutations as well as impaired hepatic BCAA catabolism, a metabolic hallmark of T2DM. The potential HCC-preventive effect of yogurt may be caused by lactobacilli-mediated degradation of BCAAs, inhibition of branched-chain α-ketoacid dehydrogenase kinase via production of intestinal medium-chain fatty acids as well as degradation of milk exosomes including their oncogenic miRs. A restriction of total animal protein intake realized by a vegetable-based diet is recommended for the prevention of HCC.

Sorafenib reduces steatosis-induced fibrogenesis in a human 3D co-culture model of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) affects around 25% of the worldwide population. Non-alcoholic steatohepatitis (NASH), the more progressive variant of NAFLD, is characterized by steatosis, cellular ballooning, lobular inflammation, and may culminate on hepatic stellate cell (HSC) activation, thus increasing the risk for fibrosis, cirrhosis, and HCC development. Conversely, the antifibrotic effects of sorafenib, an FDA-approved drug for HCC treatment, have been demonstrated in 2D cell cultures and animal models, but its mechanisms in a NAFLD-related microenvironment in vitro requires further investigation. Thus, a human 3D co-culture model of fatty hepatocytes and HSC was established by culturing hepatoma C3A cells, pre-treated with 1.32 mM oleic acid, with HSC LX-2 cells. The fatty C3A/LX-2 spheroids showed morphological and molecular hallmarks of altered lipid metabolism and steatosis-induced fibrogenesis, similarly to the human disease. Sorafenib (15 μM) for 72 hours reduced fatty spheroid viability, and upregulated the expression of lipid oxidation- and hydrolysis-related genes, CPT1 and LIPC, respectively. Sorafenib also inhibited steatosis-induced fibrogenesis by downregulating COL1A1, TGFB1, PDGF, and TIMP1 and by decreasing protein levels of IL-6, TGF-β1, and TNF-α in fatty spheroids. The demonstration of the antifibrotic properties of sorafenib on steatosis-induced fibrogenesis in a 3D in vitro model of NAFLD supports its clinical use as a therapeutic agent for the treatment of NAFLD/NASH patients.

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

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

miR-16 integrates signal pathways in myofibroblasts: determinant of cell fate necessary for fibrosis resolution

Liver fibrosis is characterized by the transdifferentiation of hepatic stellate cells (HSCs) to myofibroblasts and poor response to treatment. This can be attributed to the myofibroblast-specific resistance to phenotype reversal. In this study, we complemented miR-16 into miR-16-deficient myofibroblasts and analyzed the global role of miR-16 using transcriptome profiling and generating a pathway-based action model underlying transcriptomic regulation. Phenotypic analysis of myofibroblasts and fibrogenic characterization were used to understand the effect of miR-16 on phenotypic remodeling of myofibroblasts. miR-16 expression altered the transcriptome of myofibroblasts to resemble that of HSCs. Simultaneous targeting of Smad2 and Wnt3a, etc. by miR-16 integrated signaling pathways of TGF-β and Wnt, etc., which underlay the comprehensive regulation of transcriptome. The synergistic effect of miR-16 on the signaling pathways abolished the phenotypic characteristics of myofibroblasts, including collagen production and inhibition of adipogenesis. In vivo, myofibroblast-specific expression of miR-16 not only eliminated mesenchymal cells with myofibroblast characteristics but also restored the phenotype of HSCs in perisinusoidal space. This phenotypic remodeling resolved liver fibrosis induced by chronic wound healing. Therefore, miR-16 may integrate signaling pathways crucial for the fate determination of myofibroblasts. Its global effect induces the reversal of HSC-to-myofibroblast transdifferentiation and, subsequently, the resolution of fibrogenesis. Taken together, these findings highlight the potential of miR-16 as a promising therapeutic target for liver fibrosis.

Role of phosphatidylinositol 3-kinase signaling pathway in radiation-induced liver injury

Transforming growth factor-β1 (TGF-β1) is one of critical cytokines in radiation-induced liver injury. Hepatic stellate cells (HSC) are activated in the early stage of radiation-induced liver injury. However, it is currently unclear whether phosphatidylinositol 3-kinase (PI3K/Akt) signal pathway is activated in radiation-induced liver injury. Herein, male Sprague-Dawley rats were irradiated with 6 MV X-rays (30 Gy) on the right liver. Next, Hematoxylin and eosin staining, Masson staining, and electron microscopy were performed to examine pathological changes. Immunohistochemistry was performed to assess the expression of TGF-β1, α-SMA, and p-Akt (S473) in liver tissues. In vitro, rat HSC cell line HSC-T6 cells were given different doses of 6 MV X-ray irradiation (10 and 20 Gy) and treated with LY294002. The expression of α-SMA and p-Akt in mRNA and protein levels were measured by reverse transcription-polymerase chain reactioin (RT-PCR) and Western blot. TGF-β1 expression was detected by enzyme-linked immuno sorbent assay (ELISA). After irradiation, the liver tissues showed obvious pathological changes, indicating the establishment of the radiation-induced liver injury. Expression levels of TGF-β1, α-SMA, and p-Akt (S473) protein in liver tissues were significantly increased after irradiation, and this increase was in a time-dependent manner, suggesting the activation of HSC and PI3K/Akt signal pathway. in vitro experiments showed that the TGF-β1 secreted by HSCs, and the expression of Akt and α-SMA at mRNA and protein levels were significantly increased in irradiation groups. However, the expression of TGF-β1, Akt, and α-SMA were significantly decreased in PI3K/Akt signal pathway inhibitor LY294002-treated group. Our results suggest that during radiation-induced liver injury, HSCs are activated by TGF-β1-mediated PI3K/Akt signal pathway.

AGAP2: Modulating TGFβ1-Signaling in the Regulation of Liver Fibrosis

AGAP2 (Arf GAP with GTP-binding protein-like domain, Ankyrin repeat and PH domain 2) isoform 2 is a protein that belongs to the Arf GAP (GTPase activating protein) protein family. These proteins act as GTPase switches for Arfs, which are Ras superfamily members, being therefore involved in signaling regulation. Arf GAP proteins have been shown to participate in several cellular functions including membrane trafficking and actin cytoskeleton remodeling. AGAP2 is a multi-tasking Arf GAP that also presents GTPase activity and is involved in several signaling pathways related with apoptosis, cell survival, migration, and receptor trafficking. The increase of AGAP2 levels is associated with pathologies as cancer and fibrosis. Transforming growth factor beta-1 (TGF-β1) is the most potent pro-fibrotic cytokine identified to date, currently accepted as the principal mediator of the fibrotic response in liver, lung, and kidney. Recent literature has described that the expression of AGAP2 modulates some of the pro-fibrotic effects described for TGF-β1 in the liver. The present review is focused on the interrelated molecular effects between AGAP2 and TGFβ1 expression, presenting AGAP2 as a new player in the signaling of this pro-fibrotic cytokine, thereby contributing to the progression of hepatic fibrosis.

Role of AGAP2 in the profibrogenic effects induced by TGFβ in LX-2 hepatic stellate cells

Liver damage induces hepatic stellate cells (HSC) activation, characterised by a fibrogenic, proliferative and migratory phenotype. Activated HSC are mainly regulated by transforming growth factor β 1 (TGFβ1), which increases the production of extracellular matrix proteins (e.g. collagen-I) promoting the progression of hepatic fibrosis. AGAP2 (ArfGAP with GTPase domain, ankyrin repeat and PH domain 2) is a GTPase/GTP-activating protein involved in the actin remodelling system and receptor recycling. In the present work the role of AGAP2 in human HSC in response to TGFβ1 was investigated. LX-2 HSC were transfected with AGAP2 siRNA and treated with TGFβ1. AGAP2 knockdown prevented to some extent the proliferative and migratory TGFβ1-induced capacities of LX-2 cells. An array focused on human fibrosis revealed that AGAP2 knockdown partially prevented TGFβ1-mediated gene expression of the fibrogenic genes ACTA2, COL1A2, EDN1, INHBE, LOX, PDGFB, TGFΒ12, while favored the expression of CXCR4, IL1A, MMP1, MMP3 and MMP9 genes. Furthermore, TGFβ1 induced AGAP2 promoter activation and its protein expression in LX-2. Moreover, AGAP2 protein levels were significantly increased in liver samples from rats with thioacetamide-induced fibrosis. In addition, AGAP2 silencing affected TGFβ1-receptor 2 (TGFR2) trafficking in U2OS cells, blocking its effective recycling to the membrane. AGAP2 silencing in LX-2 cells prevented the TGFβ1-induced increase of collagen-I protein levels, while its overexpression enhanced collagen-I protein expression in the presence or absence of the cytokine. AGAP2 overexpression also increased focal adhesion kinase (FAK) phosphorylated levels in LX-2 cells. FAK and MEK1 inhibitors prevented the increase of collagen-I expression caused by TGFβ1 in LX-2 overexpressing AGAP2. In summary, the present work shows for the first time, that AGAP2 is a potential new target involved in TGFβ1 signalling, contributing to the progression of hepatic fibrosis.

Thymosin β4 inhibits PDGF-BB induced activation, proliferation, and migration of human hepatic stellate cells via its actin-binding domain

OBJECTIVES

Hepatic stellate cells (HSC) trans-differentiation is central to the development of liver fibrosis, marked by the expression of pro-fibrogenic genes and the proliferation and migration of activated HSC. Therefore, preventing and/or reverting the activation, proliferation, and migration of HSC may lead to new therapies for treating fibrosis/cirrhosis. Thymosin β4 (Tβ4) inhibits PDGF-BB-induced fibrogenesis, proliferation and migration of HSC by blocking Akt phosphorylation. Here, we utilized Tβ4-derived peptides: amino-terminal-Ac-SDKPDMAEIEKFDKS (1-15aa) and actin-binding-LKKTETQ (17-23aa) to investigate the molecular mechanisms in the anti-fibrogenic actions of Tβ4.

METHODS

We used RT-PCR, Western blot, and proliferation and migration assays in early passages of human HSC cultures treated with PDGF-BB and/or Tβ4 peptides.

RESULTS

We showed that 17-23aa but not 1-15aa inhibited PDGF-BB-dependent up-regulation of PDGFβ receptor, α-SMA, and collagen 1. It also blunted the phosphorylation of Akt at T 308 and S473, resulting in the inhibition of phosphorylation of PRAS40, and HSC proliferation and migration. Interestingly, 1-15aa blocked Akt phosphorylation at S473, but not T308 by inhibiting mTOR phosphorylation, thus, it did not have any effect on HSC proliferation and migration.

CONCLUSION

These findings suggest that while 1-15aa has a minor effect on Akt phosphorylation, the anti-fibrogenic actions of Tβ4 are exerted via 17-23aa.

Molecular pathways of nonalcoholic fatty liver disease development and progression

Nonalcoholic fatty liver disease (NAFLD) is a main hepatic manifestation of metabolic syndrome. It represents a wide spectrum of histopathological abnormalities ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) with or without fibrosis and, eventually, cirrhosis and hepatocellular carcinoma. While hepatic simple steatosis seems to be a rather benign manifestation of hepatic triglyceride accumulation, the buildup of highly toxic free fatty acids associated with insulin resistance-induced massive free fatty acid mobilization from adipose tissue and the increased de novo hepatic fatty acid synthesis from glucose acts as the "first hit" for NAFLD development. NAFLD progression seems to involve the occurrence of "parallel, multiple-hit" injuries, such as oxidative stress-induced mitochondrial dysfunction, endoplasmic reticulum stress, endotoxin-induced, TLR4-dependent release of inflammatory cytokines, and iron overload, among many others. These deleterious factors are responsible for the triggering of a number of signaling cascades leading to inflammation, cell death, and fibrosis, the hallmarks of NASH. This review is aimed at integrating the overwhelming progress made in the characterization of the physiopathological mechanisms of NAFLD at a molecular level, to better understand the factor influencing the initiation and progression of the disease.

Corneal chemical burn treatment through a delivery system consisting of TGF-β1 siRNA: in vitro and in vivo

Chemical burns are major causes of corneal blindness. Transforming growth factor beta-1 (TGFβ₁) plays an important role in induction of corneal inflammation-related-fibrosis leading to the blindness. Here, a topical delivery system consisting anti-fibrotic TGF-β₁ siRNA, an inflammatory suppressing gene, was designed for treatment of corneal injuries. TGF-β₁ siRNA loaded in nanoparticles (NPs) made up of polyethyleneimine polymer demonstrated high fibroblast transfection efficiency. Moreover, TGF-β₁ and PDGF genes and ECM deposition were suppressed in isolated human corneal fibroblasts. NPs inhibited proliferation and transformation of fibroblasts to myofibroblasts by S-phase arrest and α-SMA suppression in vitro, respectively. The mentioned finding was also confirmed in vivo, addressing high wound-healing potential of prepared gene delivery system which was superior to conventional betamethasone treatment. Besides, CD4⁺ and α-SMA antibody staining showed inhibited angiogenesis and myofibroblast accumulation in treated corneas. This study opens a new way for treating corneal fibrosis through topical siRNA delivery.

Artificial MicroRNA-Mediated Tgfbr2 and Pdgfrb Co-Silencing Ameliorates Carbon Tetrachloride-Induced Hepatic Fibrosis in Mice

Hepatic stellate cells (HSCs) are the primary cell type responsible for liver fibrogenesis. Transforming growth factor beta 1 (TGF-β1) and platelet-derived growth factor (PDGF) are key profibrotic cytokines that regulate HSC activation and proliferation with functional convergence. Dual RNA interference against their receptors may achieve therapeutic effects. A novel RNAi strategy based on HSC-specific GFAP promoter-driven and lentiviral-expressed artificial microRNAs (amiRNAs) was devised that consists of an microRNA-30a backbone and effective shRNAs against mouse Pdgfrβ and Tgfbr2. Then, its antifibrotic efficacy was tested in primary and cultured HSCs and in mice affected with carbon tetrachloride-induced hepatic fibrosis. The study shows that amiRNA-mediated Pdgfrβ and Tgfbr2 co-silencing inhibits HSC activation and proliferation. After recombinant lentiviral particles were delivered into the liver via tail-vein injection, therapeutic amiRNAs were preferentially expressed in HSCs and efficiently co-knocked down in situ Tgfbr2 and Pdgfrβ expression, which correlates with downregulated expression of target or effector genes of their signaling, which include Pai-1, P70S6K, and D-cyclins. amiRNA-based HSC-specific co-silencing of Tgfbr2 and Pdgfrβ significantly suppressed hepatic expression of fibrotic markers α-Sma and Col1a1, extracellular matrix regulators Mmps and Timp1, and phenotypically ameliorated liver fibrosis, as indicated by reductions in serum alanine aminotransferase activity, collagen deposition, and α-Sma-positive staining. The findings provide proof of concept for the use of amiRNA-mediated co-silencing of two profibrogenic pathways in liver fibrosis treatment and highlight the therapeutic potential of concatenated amiRNAs for gene therapy.

Growth Differentiation Factor 15 Predicts Chronic Liver Disease Severity

Background/Aims

Growth differentiation factor 15 (GDF-15) belongs to the transforming growth factor-β superfamily. GDF-15 is emerging as a biomarker for several diseases. The aim of this study was to determine the clinical performances of GDF-15 for the prediction of liver fibrosis and severity in chronic liver disease.

Methods

The serum GDF-15 levels were examined via enzyme immunoassay in 145 patients with chronic liver disease and 101 healthy individuals. The patients with chronic liver disease consisted of 54 patients with chronic hepatitis, 44 patients with compensated liver cirrhosis, and 47 patients with decompensated liver cirrhosis.

Results

Of the patients with chronic liver diseases, the decompensated liver cirrhosis patients had an increased serum GDF-15 (3,483 ng/L) level compared with the patients with compensated liver cirrhosis (1,861 ng/L) and chronic hepatitis (1,232 ng/L). The overall diagnostic accuracies of GDF-15, as determined by the area under the receiver operating characteristic curves, were as follows: chronic hepatitis=0.656 (>574 ng/L, sensitivity, 53.7%; specificity, 79.2%), compensated liver cirrhosis=0.886 (>760 ng/L, sensitivity, 75.6%; specificity, 92.1%), and decompensated liver cirrhosis=0.984 (>869 ng/L, sensitivity, 97.9%; specificity, 94.1%).

Conclusions

This investigation represents the first study to demonstrate the availability of GDF-15 in chronic liver disease. GDF-15 comprised a useful biomarker for the prediction of liver fibrosis and severity in chronic liver disease.

Branched-chain amino acids prevent hepatic fibrosis and development of hepatocellular carcinoma in a non-alcoholic steatohepatitis mouse model

Oral supplementation with branched-chain amino acids (BCAA; leucine, isoleucine, and valine) in patients with liver cirrhosis potentially suppresses the incidence of hepatocellular carcinoma (HCC) and improves event-free survival. However, the detailed mechanisms of BCAA action have not been fully elucidated. BCAA were administered to atherogenic and high-fat (Ath+HF) diet-induced nonalcoholic steatohepatitis (NASH) model mice. Liver histology, tumor incidence, and gene expression profiles were evaluated. Ath+HF diet mice developed hepatic tumors at a high frequency at 68 weeks. BCAA supplementation significantly improved hepatic steatosis, inflammation, fibrosis, and tumors in Ath+HF mice at 68 weeks. GeneChip analysis demonstrated the significant resolution of pro-fibrotic gene expression by BCAA supplementation. The anti-fibrotic effect of BCAA was confirmed further using platelet-derived growth factor C transgenic mice, which develop hepatic fibrosis and tumors. In vitro, BCAA restored the transforming growth factor (TGF)-β1-stimulated expression of pro-fibrotic genes in hepatic stellate cells (HSC). In hepatocytes, BCAA restored TGF-β1-induced apoptosis, lipogenesis, and Wnt/β-Catenin signaling, and inhibited the transformation of WB-F344 rat liver epithelial stem-like cells. BCAA repressed the promoter activity of TGFβ1R1 by inhibiting the expression of the transcription factor NFY and histone acetyltransferase p300. Interestingly, the inhibitory effect of BCAA on TGF-β1 signaling was mTORC1 activity-dependent, suggesting the presence of negative feedback regulation from mTORC1 to TGF-β1 signaling. Thus, BCAA induce an anti-fibrotic effect in HSC, prevent apoptosis in hepatocytes, and decrease the incidence of HCC; therefore, BCAA supplementation would be beneficial for patients with advanced liver fibrosis with a high risk of HCC.

PDGF signaling pathway in hepatic fibrosis pathogenesis and therapeutics (Review)

The platelet‑derived growth factor (PDFG) signaling pathway exerts persistent activation in response to a variety of stimuli and facilitates the progression of hepatic fibrosis. Since this pathway modulates a broad spectrum of cellular processes, including cell growth, differentiation, inflammation and carcinogenesis, it has emerged as a therapeutic target for hepatic fibrosis and liver‑associated disorders. The present review exhibits the current knowledge of the role of the PDGF signaling pathway and its pathological profiles in hepatic fibrosis, and assesses the potential of inhibitors which have been investigated in the experimental hepatic fibrosis model, in addition to the clinical challenges associated with these inhibitors.

Novel insights into a reputably irreversible process: combined mRNA and miRNA profiling of tissue from vesicourethral anastomotic stenosis after radical prostatectomy

PURPOSE

Until recently, tissue fibrosis-ultimately leading to permanent scaring-has been considered an irreversible process. However, recent findings indicate that it may be reversible after all. Vesicourethral anastomotic stenosis (VUAS) as fibrous narrowing is a frequent complication after radical prostatectomy with high recurrence rates and requires invasive treatment. The pathophysiology is poorly understood. Therefore, a combined mRNA and miRNA transcription profiling in tissue from VUAS was performed using nCounter technology.

METHODS

To assess tissue morphology and fiber composition, histochemical staining was performed. RNA expression of healthy and fibrotic tissue of twelve patients was analyzed using the human miRNA panel v3 and mRNA PanCancer pathway panel on the nCounter gene1 system and qRT-PCR. Differential expression data analysis was performed using the nSolver software implementing the R-based advanced pathway analysis tool. miRWalk2.0 was used for miRNA target prediction.

RESULTS

More linearized tissue architecture, increased collagens, and decreased elastic fibers were observed in VUAS samples. 23 miRNAs and 118 protein coding genes were differentially expressed (p < 0.01) in fibrotic tissue. miRNA target prediction and overlap analysis indicated an interaction of the strongest deregulated miRNAs with 29 deregulated mRNAs. Pathway analysis revealed alterations in DNA repair, cell cycle regulation, and TGF-beta signaling. qRT-PCR confirmed differential expression of top deregulated miRNAs and mRNAs.

CONCLUSIONS

In VUAS tissue, severe alterations on mRNA and miRNA level are found. These consistent changes give insights into the pathogenesis of VUAS after radical prostatectomy and point to future options for transcriptomics-based risk stratification and targeted therapies.

Herbal Formula, Baogan Yihao (BGYH), Prevented Dimethylnitrosamine(DMN)-Induced Liver Injury in Rats

Preclinical Research Baogan Yihao (BGYH) is a traditional Chinese herbal medicine for the treatment of chronic liver diseases. In this study, the effects of BGYH on dimethylnitrosamine (DMN)-induced liver fibrosis were investigated using a rat model. BGYH alleviate liver damage, as indicated by decreased levels of AST, ALT, γ-GT, and AKP. BGYH also prevented collagen deposition and reduced pathological tissue injury in liver tissue. In fibrosis, high levels of α-SMA and TGF-β in liver tissue were markedly attenuated by BGYH. The inhibitory effect of BGYH on HSC-T6 proliferation demonstrated that BGYH exhibited significant hepatoprotective and antifibrogenic effects on DMN-induced liver injury. These findings suggest that BGYH may have therapeutic potential in the prevention and therapy of liver fibrosis. Drug Dev Res 78 : 155-163, 2017. © 2017 Wiley Periodicals, Inc.

Both MAPK and STAT3 signal transduction pathways are necessary for IL-6-dependent hepatic stellate cells activation

Background

During liver injury, hepatic stellate cells (HSCs) can undergo activation and transform into alpha-smooth muscle actin (αSMA)-expressing contractile myofibroblast-like cells, leading to deposition of excessive scar matrix. We have recently demonstrated that depletion of adenosine deaminase acting on double-stranded RNA (ADAR1) from mouse hepatocytes leads to HSC activation and induction of inflammation and hepatic fibrosis that is mediated by interleukin 6 (IL-6). Our aim was to identify and characterize the molecular pathways involved in the direct, inflammation-independent activation of HSCs by IL-6.

Methods

Primary HSCs were isolated from mouse livers. mRNA levels of αSMA and Col1a were analyzed using qRT-PCR. Protein levels of αSMA, MAPK, p-MAPK, p38, p-p38, STAT3 and p-STAT3 were assessed by Western Blot analysis. The effect of specific signal transduction pathway inhibitors (i.e., SB203580 (P-38 inhibitor), U0126 (MAPK inhibitor), S3I-201 (STAT3 inhibitor) and Ruxolitinib (Jak1/2 inhibitor)) was also studied.

Results

Primary HSCs treated with IL-6 demonstrated upregulation of αSMA and Col1a mRNA levels as well as increased αSMA protein levels. Moreover, the phenotypic transition of quiescent HSCs toward myofibroblast-like cells was noted upon administration of IL-6 and not in untreated samples. In addition, the phosphorylation levels of p38, MAPK and STAT3 increased 30 minutes after treatment, and was followed by a decline in the phosphorylation levels 2–4 hours post-treatment. However, addition of specific signal transduction pathway inhibitors curbed this effect, and resulted in αSMA and Col1a expression levels similar to those measured in untreated control samples.

Conclusion

IL-6 can directly induce the transition of HSCs toward myofibroblast-like cells. The effect is mediated by the activation of both MAPK and JAK/STAT signaling pathways. Elimination of either MAPK or JAK/STAT signaling pathways inhibits HSC stimulation. These results might pave the road toward the development of potential therapeutic interventions for hepatic fibrosis.

Anti-fibrotic effects of Salvia miltiorrhiza and Ligustrazine Injection on LX-2 cells involved with increased N-myc downstream-regulated gene 2 expression

OBJECTIVE

To investigate the effects of Salvia miltiorrhiza and Ligustrazine Injection (SML) on proliferation and apoptosis of human hepatic stellate cell LX-2 and the expression of N-myc downstreamregulated gene 2 (NDRG2, a tumor suppressor gene).

METHODS

HSCs from the LX-2 cell line were cultured in vitro. The proliferative state of different initial LX-2 cell numbers was measured using a 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. LX-2 cells were plated in 96-well plates at an approximate density of 2.50×10⁴ cells/mL and cultured for 24 h followed by the application of different concentrations of SML (1, 2, 4 and 8 μL/mL). Cell proliferation was measured using the MTT assay at 24 and 48 h. Apoptosis was detected by flow cytometry at 24 h. LX-2 cells were treated with different concentrations of SML and extracted with protein lysis buffer. The levels of NDRG2 and β-catenin were measured by Western blot.

RESULTS

With the exception of the 1 and 2 μL/mL concentrations, 4 and 8 μL/mL SML inhibited cell proliferation in a concentration-dependent manner at 24 and 48 h (P<0.05). With the exception of the 1 and 2 μL/mL concentrations, the NDRG2 expression level was greatly increased in a concentration-dependent manner. However, the level of β-catenin was unaffected.

CONCLUSION

SML inhibit LX-2 cell proliferation in a concentration-dependent manner, and the mechanism may be associated with NDRG2 over-expression.

Rev-erb agonist and TGF-β similarly affect autophagy but differentially regulate hepatic stellate cell fibrogenic phenotype

We demonstrated that ligand-activated nuclear receptor Rev-erbα mitigates CCl₄-induced liver fibrosis. Rev-erbα is also a novel regulator of autophagy, a crucial eukaryotic catabolic system in which lysosomes degrade substrates for energy generation. In hepatic stellate cells (HSC) autophagy is reportedly required for this purpose to activate HSCs during fibrogenesis. Here, we examined whether pharmacological activation of Rev-erb with its synthetic ligand SR9009 or treatment with the pro-fibrotic cytokine, TGF-β, each differentially modulate autophagy to regulate the HSC phenotype. We measured the effects of SR9009 on autophagy markers in a CCl₄-induced liver fibrosis model. Using primary and immortalized HSCs in vitro, we quantified SR9009 and TGF-β effects on autophagy flux. Compared with vehicle-treated controls, livers from CCl₄-treated mice exhibited lower AMPK, higher P70S6K phosphorylation, elevated P62 and lower levels of ATG proteins, indicating a disruption of autophagosome (AV) formation. SR9009 treatment prevented CCl₄-induced P70S6K phosphorylation but did not affect CCl₄-induced changes in AMPK, ATG proteins or P62. Analysis of autophagy markers and autophagy flux in primary HSCs or an immortalized human HSC line (LX2), revealed that SR9009 exposure down-regulated AV biogenesis. These events were associated with lower levels of fibrogenic gene expression, P70S6K phosphorylation and HSC proliferation. However, HSC exposure to TGF-β enhanced fibrogenic gene expression, P70S6K phosphorylation and HSC proliferation, while it simultaneously decelerated AV synthesis. The autophagy activator rapamycin and the autophagy inhibitor wortmannin each decreased HSC activation, P70S6K phosphorylation and HSC proliferation. Furthermore, knock-down of P70S6K using siRNA blocked basal and TGF-β-induced cell proliferation in human activated LX2. We conclude that SR9009 and TGF-β both similarly affected autophagy but, differentially regulated HSC fibrogenic phenotype through modulation of P70S6K, which is crucial for cell proliferation and fibrogenesis.

Ltbp4 regulates Pdgfrβ expression via TGFβ-dependent modulation of Nrf2 transcription factor function

Latent transforming growth factor beta binding protein 4 (LTBP4) belongs to the fibrillin/LTBP family of proteins and plays an important role as a structural component of extracellular matrix (ECM) and local regulator of TGFβ signaling. We have previously reported that Ltbp4S knock out mice (Ltbp4S-/-) develop centrilobular emphysema reminiscent of late stage COPD, which could be partially rescued by inactivating the antioxidant protein Sestrin 2 (Sesn2). More recent studies showed that Sesn2 knock out mice upregulate Pdgfrβ-controlled alveolar maintenance programs that protect against cigarette smoke induced pulmonary emphysema. Based on this, we hypothesized that the emphysema of Ltbp4S-/- mice is primarily caused by defective Pdgfrβ signaling. Here we show that LTBP4 induces Pdgfrβ signaling by inhibiting the antioxidant Nrf2/Keap1 pathway in a TGFβ-dependent manner. Overall, our data identified Ltbp4 as a major player in lung remodeling and injury repair.

Moniliformediquinone as a potential therapeutic agent, inactivation of hepatic stellate cell and inhibition of liver fibrosis in vivo

Background

Moniliformediquinone (MFD), a phenanthradiquinone in Dendrobium moniliforme, was synthesized in our laboratory. Beyond its in vitro inhibitory effects on cancer cells, other biological activity of MFD is unknown. The purpose of the present study was to investigate the effects of MFD on hepatic fibrogenesis in vitro and in vivo.

Methods

Hepatic stellate HSC-T6 was cultured. Cell viability assay and western blot analyses were performed. Male ICR mice were evaluated on CCl₄-induced hepatotoxicity using both histological examination and immunohistochemical staining.

Results

First, in vitro study showed that the synthesized MFD effectively attenuated the expression of transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), α-smooth muscle actin (α-SMA), and type I collagen (COL-1), which modulated the hepatic fibrogenesis. Furthermore, MFD reduced the phosphorylation of p65 NFκB in HSC-T6 cells. In vivo, liver fibrosis was induced by CCl₄ twice a week for 10 weeks in mice. The administration of the MFD was started after 1 week of CCl₄ thrice-weekly; the MFD significantly reduced plasma aspartate transaminase (AST) and lactose dehydrogenase (LDH) as well as hepatic hydroxy-proline, α-SMA, and COL-1 expression in CCl₄-treated mice. Pathological analysis showed that the MFD alleviated CCl₄-induced hepatic inflammation, necrosis and fibrosis. These results suggest that MFD possesses therapeutic potential for liver fibrosis.

Conclusions

The synthesized MFD exhibits anti-fibrotic potential by inactivation of HSCs in vitro and decreases mouse hepatic fibrosis in vivo. Further investigation into their clinical therapeutic potential is required.

Screening for and validation of a hepatic fibrosis-related pathway induced by insulin-like growth factor-binding protein-related protein 1

OBJECTIVE

Our previous studies characterized insulin-like growth factor-binding protein-related protein 1 (IGFBPrP1) as a molecule that promotes hepatic fibrogenesis, but its mechanism has not been fully elucidated. Here, we have investigated the effect of IGFBPrP1 on gene expression in the hepatic fibrosis-related pathway.

MATERIALS AND METHODS

Sprague-Dawley rats received injections of an adenovirus carrying IGFBPrP1 or EGFP cDNA into their tail veins. In hepatic preparations, hepatic stellate cell activation was determined by α-smooth muscle actin expression and hepatic fibrosis by Sirius red staining and hydroxyproline content analysis. IGFBPrP1-inducible genes of the hepatic fibrosis-related pathway were assessed by PCR array. Expression of IGFBPrP1 and transforming growth factor β1 (TGFβ1) and array results were evaluated by quantitative real-time PCR and western blotting.

RESULTS

IGFBPrP1-overexpressing rats showed an increase in α-smooth muscle actin expression and collagen and hydroxyproline content in the liver. The PCR array results indicated that some genes were upregulated and some were downregulated in Ad-IGFBPrP1-infected rats. Among these, Egr1, MAP2K2 (MEK2) and MAPK3 (ERK1) expression increased, whereas PTEN and Hhip mRNA expression decreased. Egr1 protein levels increased and peaked 2 weeks after infection and then decreased gradually. PTEN protein decreased gradually in Ad-IGFBPrP1-infected rats with a concurrent increase in the degree of hepatic fibrosis. TGFβ1 levels increased during hepatic fibrosis development in liver tissues.

CONCLUSION

Egr1, PTEN, Hhip, MAP2K2 (MEK2) and MAPK3 (ERK1) were identified as candidate genes of the IGFBPrP1-induced hepatic fibrosis-related pathway. IGFBPrP1 promoted hepatic fibrosis mainly by enhancing the TGFβ1 expression that it triggered.

Identification of antrodin B from Antrodia camphorata as a new anti-hepatofibrotic compound using a rapid cell screening method and biological evaluation

AIM

Liver fibrosis is the excessive accumulation of extracellular matrix (ECM) resulting from chronic liver diseases. Efficient and well-tolerated drugs for its treatment are urgently needed. This study aims to identify the active ingredients of Antrodia camphorata by a bioassay-guided fractionation approach and explore the acting mechanism by using a hepatic stellate cell (HSC) line CFSC-8B stimulated by transforming growth factor-β1 (TGF-β1).

METHODS

The accumulation of collagens was evaluated using chromogenic precipitation reaction with picro-sirius red (PSR) dye solution and quantified by spectrophotometric analysis of the dissolved stain. MTT assay, cell migration assay, quantitative polymerase chain reaction and western blotting analysis were used to determine the cell viability, cell migration and gene expression.

RESULTS

We established a rapid colorimetric assay suitable for screening of anti-hepatofibrotic reagents. Stimulation with 10 ng/mL TGF-β1 for 48 h and 200 μL PSR dye solution were optimal for the colorimetric assay in CFSC-8B cells. We used SB431542, silybin and another 11 antifibrotic reagents to verify the cellular model. Within the safe doses, they attenuated ECM production induced by TGF-β1. Bioactivity-guided fractionation led to the identification of antrodin B from A. camphorata. Antrodin B significantly ameliorated cell proliferation, cell migration, suppressed HSC activation marker α-smooth muscle actin expression and ECM components Col1, Col3 and Fn expression, and blocked the phosphorylation of Smad2/3 induced by TGF-β1 in CFSC-8B cells in a dose-dependent manner.

CONCLUSION

We developed a simple assay based on TGF-β1-induced total collagen accumulation in CFSC-8B cells and identified antrodin B which may serve as a potential candidate for treatment of liver fibrosis.

Melanoma Cells Block PEDF Production in Fibroblasts to Induce the Tumor-Promoting Phenotype of Cancer-Associated Fibroblasts

Loss of pigment epithelium-derived factor (PEDF, SERPINF1) in cancer cells is associated with poor prognosis and metastasis, but the contribution of stromal PEDF to cancer evolution is poorly understood. Therefore, we investigated the role of fibroblast-derived PEDF in melanoma progression. We demonstrate that normal dermal fibroblasts expressing high PEDF levels attenuated melanoma growth and angiogenesis in vivo, whereas PEDF-depleted fibroblasts exerted tumor-promoting effects. Accordingly, mice with global PEDF knockout were more susceptible to melanoma metastasis. We also demonstrate that normal fibroblasts in close contact with PEDF-null melanoma cells lost PEDF expression and tumor-suppressive properties. Further mechanistic investigations underlying the crosstalk between tumor and stromal cells revealed that melanoma cells produced PDGF-BB and TGFβ, which blocked PEDF production in fibroblasts. Notably, cancer-associated fibroblasts (CAF) isolated from patient-derived tumors expressed markedly low levels of PEDF. Treatment of patient CAF and TGFβ-treated normal fibroblasts with exogenous PEDF decreased the expression of CAF markers and restored PEDF expression. Finally, expression profiling of PEDF-depleted fibroblasts revealed induction of IL8, SERPINB2, hyaluronan synthase-2, and other genes associated with tumor promotion and metastasis. Collectively, our results demonstrate that PEDF maintains tumor-suppressive functions in fibroblasts to prevent CAF conversion and illustrate the mechanisms by which melanoma cells silence stromal PEDF to promote malignancy. Cancer Res; 76(8); 2265-76. ©2016 AACR.

Transfection with recombinant adenovirus vector expressing secreted frizzled related protein inhibits liver fibrosis in mice

AIM: To construct a recombinant adenovirus vector expressing secreted frizzled related protein (SFRP), and to assess the inhibitory effect of SFRP overexpression on experimental hepatic fibrosis (HF) in mice.

METHODS: Liposome-mediated transfection was used to introduce recombinant adenovirus pAd-Track-PPARγ2-CMV carrying the SFRP5 gene into liver cells from mice with CCl₄ induced HF to obtain recombinant adenovirus infected HF cells. Western blot, immunofluorescence microscopy and confocal laser microscopy were used to analyze the inhibitory effect of SFRP overexpression on experimental HF.

RESULTS: Cells infected with the recombinant adenovirus vector had higher expression of SFRP5 protein. Double immunofluorescence showed SFRP5 over expression inhibited the expression of α-smooth muscle actin (α-SMA) and fibroblast-specific protein-1 (FSP-1) in liver cells. Pathological examination revealed that SFRP5 over expression significantly reduced the occurrence of epithelial-mesenchymal transition (EMT) in liver cells (SFRP group vs control group, P < 0.05).

CONCLUSION: We have successfully constructed a recombinant adenovirus containing the SFRP5 gene, and it can effectively increase the expression of SFRP5 gene in mouse HF cells, thereby inhibiting the occurrence of EMT and HF.

GIV/Girdin is a central hub for profibrogenic signalling networks during liver fibrosis

Progressive liver fibrosis is characterized by the deposition of collagen by activated hepatic stellate cells (HSCs). Activation of HSCs is a multiple receptor-driven process in which profibrotic signals are enhanced, and anti-fibrotic pathways are suppressed. Here we report the discovery of a novel signaling platform comprised of G protein subunit, Gαi and GIV, its guanine exchange factor (GEF), which serves as a central hub within the fibrogenic signalling network initiated by diverse classes of receptors. GIV is expressed in the liver after fibrogenic injury and is required for HSC activation. Once expressed, GIV enhances the profibrotic (PI3K-Akt-FoxO1 and TGFβ-SMAD) and inhibits the anti-fibrotic (cAMP-PKA-pCREB) pathways to skew the signalling network in favor of fibrosis, all via activation of Gαi. We also provide evidence that GIV may serve as a biomarker for progression of fibrosis after liver injury and a therapeutic target for arresting and/or reversing HSC activation during liver fibrosis.

Cellular and molecular mechanisms in the pathogenesis of liver fibrosis: An update

There have been considerable recent advances towards a better understanding of the complex cellular and molecular network underlying liver fibrogenesis. Recent data indicate that the termination of fibrogenic processes and the restoration of deficient fibrolytic pathways may allow the reversal of advanced fibrosis and even cirrhosis. Therefore, efforts have been made to better clarify the cellular and molecular mechanisms that are involved in liver fibrosis. Activation of hepatic stellate cells (HSCs) remains a central event in fibrosis, complemented by other sources of matrix-producing cells, including portal fibroblasts, fibrocytes and bone marrow-derived myofibroblasts. These cells converge in a complex interaction with neighboring cells to provoke scarring in response to persistent injury. Defining the interaction of different cell types, revealing the effects of cytokines on these cells and characterizing the regulatory mechanisms that control gene expression in activated HSCs will enable the discovery of new therapeutic targets. Moreover, the characterization of different pathways associated with different etiologies aid in the development of disease-specific therapies. This article outlines recent advances regarding the cellular and molecular mechanisms involved in liver fibrosis that may be translated into future therapies. The pathogenesis of liver fibrosis associated with alcoholic liver disease, non-alcoholic fatty liver disease and viral hepatitis are also discussed to emphasize the various mechanisms involved in liver fibrosis.