Rosmarinic acid and baicalin epigenetically derepress peroxisomal proliferator-activated receptor γ in hepatic stellate cells for their antifibrotic effect

Scutellariae Radix and Coptidis Rhizoma Improve Glucose and Lipid Metabolism in T2DM Rats via Regulation of the Metabolic Profiling and MAPK/PI3K/Akt Signaling Pathway

Aim Scutellariae Radix (SR) and Coptidis Rhizoma (CR) have often been combined to cure type 2 diabetes mellitus (T2DM) in the clinical practice for over thousands of years, but their compatibility mechanism is not clear. Mitogen-activated protein kinase (MAPK) signaling pathway has been suggested to play a critical role during the process of inflammation, insulin resistance, and T2DM. This study was designed to investigate their compatibility effects on T2DM rats and explore the underlying mechanisms by analyzing the metabolic profiling and MAPK/PI3K/Akt signaling pathway. Methods The compatibility effects of SR and CR were evaluated with T2DM rats induced by a high-fat diet (HFD) along with a low dose of streptozocin (STZ). Ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was performed to discover potential biomarkers. The levels of pro-inflammatory cytokines; biochemical indexes in serum, and the activities of key enzymes related to glycometabolism in liver were assessed by ELISA kits. qPCR was applied to examine mRNA levels of key targets in MAPK and insulin signaling pathways. Protein expressions of p65; p-p65; phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K); phosphorylated-PI3K (p-PI3K); protein kinase B (Akt); phosphorylated Akt (p-Akt) and glucose transporter 2 (Glut2) in liver were investigated by Western blot analysis. Results Remarkably, hyperglycaemia, dyslipidemia, inflammation, and insulin resistance in T2DM were ameliorated after oral administration of SR and CR, particularly their combined extracts. The effects of SR, CR, low dose of combined extracts (LSC) and high dose of combined extracts (HSC) on pro-inflammatory cytokine transcription in T2DM rats showed that the MAPK pathway might account for the phenomenon with down-regulation of MAPK (P38 mitogen-activated protein kinases (P38), extracellular regulated protein kinases (ERK), and c-Jun N-terminal kinase (JNK)) mRNA, and protein reduction in p-P65. While mRNA levels of key targets such as insulin receptor substrate 1 (IRS1), PI3K, Akt2, and Glut2 in the insulin signaling pathway were notably up-modulated, phosphorylations of PI3K, Akt, and expression of Glut2 were markedly enhanced. Moreover, the increased activities of phosphoenolpyruvate carboxykinase (PEPCK), fructose-1,6-bisphosphatase (FBPase), glucose 6-phosphatase (G6Pase), and glycogen phosphorylase (GP) were highly reduced and the decreased activities of glucokinase (GK), phosphofructokinase (PFK), pyruvate kinase (PK), and glycogen synthase (GS) in liver were notably increased after treatment. Further investigation indicated that the metabolic profiles of plasma and urine were clearly improved in T2DM rats. Fourteen potential biomarkers (nine in plasma and five in urine) were identified. After intervention, these biomarkers returned to normal level to some extent. Conclusion The results showed that SR, CR, and combined extract groups were normalized. The effects of combined extracts were more remarkable than single herb treatment. Additionally, this study also showed that the metabonomics method is a promising tool to unravel how traditional Chinese medicines work.

Rosmarinic Acid Combined with Adriamycin Induces Apoptosis by Triggering Mitochondria-Mediated Signaling Pathway in HepG2 and Bel-7402 Cells

BACKGROUND Hepatic carcinoma is the third leading cause of cancer-related deaths. This study aimed to evaluate the anti-tumor effects of rosmarinic acid (RosA) combined with Adriamycin (ADM) on proliferation and apoptosis of hepatic carcinoma cell lines. MATERIAL AND METHODS Human HepG2 and Bel-7402 cells were treated with RosA and ADM and divided into HepG2 or Bel-7402, 25 μg/ml, 50 μg/m, and 100 μg/ml RosA+0.4 μg/ml ADM groups, respectively. The Cell Counting Kit-8 (CCK-8) assay was used to evaluate cell viability. Immunohistochemistry assay was used to examine B cell lymphoma-2 (Bcl-2) and Bcl-2-associated X (Bax) expression. Cell cycle analysis was used to detect cell cycle distribution. Flow cytometry and terminal deoxynucleotidyl transferase-mediated d-UTP nick-end labeling (TUNEL) assay were utilized to evaluate apoptosis. RESULTS RosA combined with ADM damaged cell morphology and decreased cell viability, and significantly decreased S-phase cell numbers compared to the HepG2 or Bel-7402 group (p<0.05). Apoptosis rates in the RosA combined with ADM group were significantly increased compared to the HepG2 or Bel-7402 group (p<0.05). TUNEL assay showed that RosA combined with ADM significantly induced DNA damage (TUNEL-positive staining) in the HepG2 and Bel-7402 groups (p<0.05). RosA combined with ADM significantly reduced Bcl-2 expression in HepG2 or Bel-7402 cells (p<0.05). RosA combined with ADM significantly increased Bax expression in HepG2 and Bel-7402 cells (p<0.05). Cell viability, apoptosis, cell cycle, and Bcl-2 and Bax expression were changed with increased concentrations of RosA. CONCLUSIONS RosA combined with ADM damaged tumor cell morphologies, decreased cell viability, and induced apoptosis of HepG2 and Bel-7402 by triggering the mitochondria-mediated signaling pathway.

Baicalein Targets GTPase-Mediated Autophagy to Eliminate Liver Tumor-Initiating Stem Cell-Like Cells Resistant to mTORC1 Inhibition

Drug resistance is a major problem in the treatment of liver cancer. Mammalian Target of Rapamycin 1 (mTORC1) inhibitors have been tested for the treatment of liver cancer based on hyperactive mTOR in this malignancy. However, their clinical trials showed poor outcome, most likely due to their ability to upregulate CD133 and promote chemoresistance. The CD133+ tumor-initiating stem cell-like cells (TICs) isolated from mouse and human liver tumors are chemoresistant, and identification of an approach to abrogate this resistance is desired. In search of a compound that rescinds resistance of TICs to mTORC1 inhibition and improves chemotherapy, we identified baicalein (BC), which selectively chemosensitizes TICs and the human hepatocellular carcinoma (HCC) cell line Huh7 cells but not mouse and human primary hepatocytes. Nanobead pull-down and mass-spectrometric analysis, biochemical binding assay, and three-dimensional computational modeling studies reveal BC's ability to competitively inhibit guanosine triphosphate binding of SAR1B guanosine triphosphatase, which is essential for autophagy. Indeed, BC suppresses autophagy induced by an mTORC1 inhibitor and synergizes cell death caused by mTORC1 inhibition in TIC and Huh7 spheroid formation and in the patient-derived xenograft model of HCC. The BC-induced chemosensitization is rescued by SAR1B expression and phenocopied by SAR1B knockdown in cancer cells treated with a mTORC1 inhibitor. Conclusion: These results identify SAR1B as a target in liver TICs and HCC cells resistant to mTORC1 inhibition.

Loureirin B inhibits the proliferation of hepatic stellate cells and the Wnt/β-catenin signaling pathway by regulating miR-148-3p

BACKGROUND

We investigated the activity of loureirin B against liver fibrosis and the underlying molecular mechanisms.

METHODS

Hepatic stellate cells (HSCs) from Sprague-Dawley rats were treated with different concentrations of loureirin B. We used the MTT assay to determine HSC proliferation, flow cytometry to analyze apoptosis, and western blot to determine the expressions of Bax, Bcl-2, Wnt1 and β-catenin. Real-time PCR was used to determine the expressions of Wnt1 and miR-148-3p.

RESULTS

The MTT assay showed that loureirin B treatment significantly inhibited the proliferation of HSCs in time- and dose-dependent manners. Loureirin B significantly promoted the apoptosis of HSCs, increased the expression of Bax and decreased the Bcl-2 level. Western blot analysis showed that the expressions of Wnt1 and β-catenin were obviously lower in the loureirin B treatment group than in the control group. We also found that loureirin B could decrease the Wnt1 mRNA level and increase miR-148-3p expression. Knockdown of miR-148-3p using inhibitor could reverse the effects of loureirin B on the proliferation and apoptosis of HSCs and the expressions of Bax, Bcl-2, Wnt1 and β-catenin.

CONCLUSION

Our results suggest that loureirin B inhibited the proliferation and promoted the apoptosis of HSCs, and suppressed the Wnt/β-catenin signaling pathway via regulation of miR-148-3p.

Protective effects of Liuweiwuling tablets on carbon tetrachloride-induced hepatic fibrosis in rats

BACKGROUND

Liuweiwuling tablets (LWWL) are an herbal product that exerts remarkable effects on liver protection and aminotransferase levels, and they have been approved by the Chinese State Food and Drug Administration (CFDA). Clinical studies have found that LWWL can inhibit collagen production and reduce the levels of liver fibrosis markers in the serum. Thus, LWWL is expected to have beneficial effects in the treatment of liver fibrosis. The purpose of this study was to evaluate the pharmacological effects of LWWL.

METHODS

Hepatic fibrosis was induced in rats via carbon tetrachloride (CCl₄) treatment. The rats were treated twice weekly for 8 weeks with either 2 mL·kg^- 1 body weight of a 50% solution of CCl₄ in olive oil or olive oil alone by oral gavage. A subset of rats received daily intraperitoneal injections of either colchicine (0.2 mg/kg per day), LWWL (0.4, 1.6, or 6.4 g/kg per day), or vehicle (N = 12 for all groups) during weeks 9-12. The rats were sacrificed after 12 weeks. Pathological changes in hepatic tissue were examined using hematoxylin and eosin (H&E) and Sirius Red staining. Immunohistochemistry was performed to observe α-smooth muscle actin (α-SMA) and collagen type I (collagen I) protein expression. Western blotting was also used to detect α-SMA protein expression. Real-time quantitative reverse-transcription polymerase chain reaction (RT-qPCR) was used to detect transforming growth factor-1 (TGF-β1), platelet-derived growth factor (PDGF), tissue inhibitor of metalloproteinase-1 (TIMP1), and tissue inhibitor of metalloproteinase-2 (TIMP2) mRNA expression.

RESULTS

LWWL significantly reversed histological fibrosis and liver injury, reduced the hydroxyproline content in liver tissue, and decreased α-SMA and collagen I expression. LWWL also suppressed hepatic stellate cell (HSC) activation by reducing the expression of the profibrogenic factors TGF-β1 and PDGF. The expression levels of TIMP1 and TIMP2, which regulate extracellular matrix (ECM) degradation, were decreased after CCl₄ injury in LWWL-treated rats.

CONCLUSIONS

These data suggest that LWWL may serve as a promising therapeutic agent to reduce fibrogenesis.

The Active Components of Fuzheng Huayu Formula and Their Potential Mechanism of Action in Inhibiting the Hepatic Stellate Cells Viability - A Network Pharmacology and Transcriptomics Approach

Purpose: This study aimed to identify the active components of Fuzheng Huayu (FZHY) formula and the mechanism by which they inhibit the viability of hepatic stellate cells (HSCs) by a combination of network pharmacology and transcriptomics.

Methods: The active components of FZHY formula were screened out by text mining. Similarity match and molecular docking were used to predict the target proteins of these compounds. We then searched the STRING database to analyze the key enriched processes, pathways and related diseases of these target proteins. The relevant networks were constructed by Cytoscape. A network analysis method was established by integrating data from above network pharmacology with known transcriptomics analysis of quiescent HSCs-activated HSCs to identify the most possible targets of the active components in FZHY formula. A cell-based assay (LX-2 and T6 cells) and surface plasmon resonance (SPR) analysis were used to validate the most possible active component-target protein interactions (CTPIs).

Results: 40 active ingredients in FZHY formula and their 79 potential target proteins were identified by network pharmacology approach. Further network analysis reduced the 79 potential target proteins to 31, which were considered more likely to be the target proteins of the active components in FZHY formula. In addition, further enrichment analysis of 31 target proteins indicated that the HIF-1, PI3K-Akt, FoxO, and chemokine signaling pathways may be the primary pathways regulated by FZHY formula in inhibiting the HSCs viability for the treatment of liver fibrosis. Of the 31 target proteins, peroxisome proliferator activator receptor gamma (PPARG) was selected for validation by experiments at the cellular and molecular level. The results demonstrated that schisandrin B, salvianolic acid A and kaempferol could directly bind to PPARG, decreasing the viability of HSCs (T6 cells and LX-2 cells) and exerting anti-fibrosis effects.

Conclusion: The active ingredients of FZHY formula were successfully identified and the mechanisms by which they inhibit HSC viability determined, using network pharmacology and transcriptomics. This work is expected to benefit the clinical application of this formula.

Baicalin inhibits PDGF-BB-induced hepatic stellate cell proliferation, apoptosis, invasion, migration and activation via the miR-3595/ACSL4 axis

Hepatic fibrosis is a physiological response to liver injury that includes a range of cell types. The pathogenesis of hepatic fibrosis currently focuses on hepatic stellate cell (HSC) activation into muscle fiber cells and fibroblasts. Baicalin is a flavone glycoside. It is the glucuronide of baicalein, which is extracted from the dried roots of Scutellaria baicalensis Georgi. Previous work focused on the anti-viral, -inflammatory and -tumor properties of baicalin. However, the potential anti-fibrotic effects and mechanisms of baicalin are not known. The present study demonstrated that baicalin influenced the activation, proliferation, apoptosis, invasion and migration of platelet-derived growth factor-BB-induced activated HSC-T6 cells in a dose-dependent manner. To investigate the anti-fibrotic effect of baicalin, a one-color micro (mi)RNA array and reverse transcription-quantitative polymerase chain reaction analyses were used. Results demonstrated that baicalin increased the expression of the miRNA, miR-3595. In addition, the inhibition of miR-3595 substantially reversed the anti-fibrotic effect of baicalin. The present data also suggested that miR-3595 negatively regulates the long-chain-fatty-acid-CoA ligase 4 (ACSL4). Furthermore, ACSL4 acted in a baicalin-dependent manner to exhibit anti-fibrotic effects. Taken together, it was concluded that baicalin induces miR-3595 expression that modulates the expression levels of ACSL4. To the best of our knowledge, the present study is the first to demonstrate that baicalin induces overexpression of human miR-3595, and subsequently decreases the expression of ACSL4, resulting in an anti-fibrotic effect.

Rosmarinic acid attenuates cardiac fibrosis following long-term pressure overload via AMPKα/Smad3 signaling

Agonists of peroxisome proliferator-activated receptor gamma (PPAR-γ) can activate 5' AMP-activated protein kinase alpha (AMPKα) and exert cardioprotective effects. A previous study has demonstrated that rosmarinic acid (RA) can activate PPAR-γ, but its effect on cardiac remodeling remains largely unknown. Our study aimed to investigate the effect of RA on cardiac remodeling and to clarify the underlying mechanism. Mice were subjected to aortic banding to generate pressure overload induced cardiac remodeling and then were orally administered RA (100 mg/kg/day) for 7 weeks beginning 1 week after surgery. The morphological examination, echocardiography, and molecular markers were used to evaluate the effects of RA. To ascertain whether the beneficial effect of RA on cardiac fibrosis was mediated by AMPKα, AMPKα2 knockout mice were used. Neonatal rat cardiomyocytes and fibroblasts were separated and cultured to validate the protective effect of RA in vitro. RA-treated mice exhibited a similar hypertrophic response as mice without RA treatment, but had an attenuated fibrotic response and improved cardiac function after pressure overload. Activated AMPKα was essential for the anti-fibrotic effect of RA via inhibiting the phosphorylation and nuclear translocation of Smad3 in vivo and in vitro, and AMPKα deficiency abolished RA-mediated protective effects. Small interfering RNA against Ppar-γ (siPpar-γ) and GW9662, a specific antagonist of PPAR-γ, abolished RA-mediated AMPKα phosphorylation and alleviation of fibrotic response in vitro. RA attenuated cardiac fibrosis following long-term pressure overload via AMPKα/Smad3 signaling and PPAR-γ was required for the activation of AMPKα. RA might be a promising therapeutic agent against cardiac fibrosis.

Two CYP82D Enzymes Function as Flavone Hydroxylases in the Biosynthesis of Root-Specific 4'-Deoxyflavones in Scutellaria baicalensis

Baicalein, wogonin, and their glycosides are major bioactive compounds found in the medicinal plant Scutellaria baicalensis Georgi. These flavones can induce apoptosis in a variety of cancer cell lines but have no effect on normal cells. Furthermore, they have many additional benefits for human health, such as anti-oxidant, antiviral, and liver-protective properties. Here, we report the isolation and characterization of two CYP450 enzymes, SbCYP82D1.1 and SbCYP82D2, which function as the flavone 6-hydroxylase (F6H) and flavone 8-hydroxylase (F8H), respectively, in S. baicalensis. SbCYP82D1.1 has broad substrate specificity for flavones such as chrysin and apigenin and is responsible for biosynthesis of baicalein and scutellarein in roots and aerial parts of S. baicalensis, respectively. When the expression of SbCYP82D1.1 is knocked down, baicalin and baicalein levels are reduced significantly while chrysin glycosides accumulate in hairy roots. SbCYP82D2 is an F8H with high substrate specificity, accepting only chrysin as its substrate to produce norwogonin, although minor 6-hydroxylation activity can also be detected. Phylogenetic analysis suggested that SbCYP82D2 might have evolved from SbCYP82D1.1 via gene duplication followed by neofunctionalization, whereby the ancestral F6H activity is partially retained in the derived SbCYP82D2.

Prophylactic and curative effect of rosemary leaves extract in a bleomycin model of pulmonary fibrosis

CONTEXT

Pulmonary fibrosis is a devastating disease without effective treatment. Rosemary is appreciated since ancient times for its medicinal properties, while biomolecules originated from the plant have an antioxidant and antifibrotic effect.

OBJECTIVE

The effects of Rosmarinus officinalis L. (Lamiaceae) leaves extract (RO) on bleomycin-induced lung fibrosis were investigated.

MATERIALS AND METHODS

Male Wistar rats were given a single dose of bleomycin (BLM, 4 mg/kg, intratracheal), while RO (75 mg/kg, intraperitoneal) was administered 3 days later and continued for 4 weeks (BLM/RO1-curative group). Alternatively, RO was administered 2 weeks before BLM and continued 15 days thereafter (BLM/RO2-prophylactic group). Antioxidant activities of RO and lung tissues were studied by standard methods. Histological staining revealed lung architecture and collagen deposition. RO was characterized for its polyphenol content and by high-performance liquid chromatography.

RESULTS

RO polyphenol content was 60.52 mg/g of dry weight, carnosic and rosmarinic acids being major components (6.886 and 2.351 mg/g). Antioxidant effect of RO (DPPH and FRAP assay) expressed as IC50 values were 2.23 μg/mL and 0.074 μg/mL, respectively. In BLM/RO1 and BLM/RO2 lung architecture was less compromised compared to BLM, which was reflected in lower fibrosis score (2.33 ± 0.33 and 1.8 ± 0.32 vs 3.7 ± 0.3). Malondialdehyde levels were attenuated (141% and 108% vs 258% of normal value). Catalase and glutathione-S-transferase activities were normalized (103% and 117% vs 59%, 85% and 69% vs 23%, respectively).

DISCUSSION AND CONCLUSION

RO has a protective effect against BLM-induced oxidative stress and lung fibrosis due to its phenolic compounds.

Carnosol-mediated Sirtuin 1 activation inhibits Enhancer of Zeste Homolog 2 to attenuate liver fibrosis

Quiescent hepatic stellate cell (HSC) activation and subsequent conversion into myofibroblasts is the central event in hepatic fibrosis pathogenesis. Epithelial-mesenchymal transition (EMT), another vital participant in liver fibrosis, has the potential to initiate HSC activation, which promotes abundant myofibroblast production. Previous studies suggest that Enhancer of Zeste Homolog 2 (EZH2) plays a significant role in myofibroblast transdifferentiation; however, the underlying mechanisms remain largely unaddressed. Carnosol (CS), a compound extracted from rosemary, displays multiple pharmacological activities. This study aimed to investigate the signaling mechanisms underlying EZH2 inhibition and the anti-fibrotic effect of CS in liver fibrosis. We found that CS significantly inhibited CCl₄- and TGFβ1-induced liver fibrosis and reduced both HSC activation and EMT. EZH2 knockdown also prevented these processes induced by TGFβ1 in HSCs and AML-12 cells. Interestingly, the protective effect of CS was positively associated with Sirtuin 1 (SIRT1) activation and accompanied by EZH2 inhibition. SIRT1 knockdown attenuated the EZH2 inhibition induced by CS and increased EZH2 acetylation, which enhanced its stability. Conversely, upon TGFβ1 exposure, SIRT1 activation significantly reduced the level of EZH2 acetylation; however, EZH2 overexpression prevented the SIRT1 activation that primed myofibroblast inhibition, indicating that EZH2 is a target of SIRT1. Thus, SIRT1/EZH2 regulation could be used as a new therapeutic strategy for fibrogenesis. Together, this study provides evidence of activation of the SIRT1/EZH2 pathway by CS that inhibits myofibroblast generation, and thus, CS may represent an attractive candidate for anti-fibrotic clinical therapy.

Novel Anti-fibrotic Therapies

Fibrosis is a major player in cardiovascular disease, both as a contributor to the development of disease, as well as a post-injury response that drives progression. Despite the identification of many mechanisms responsible for cardiovascular fibrosis, to date no treatments have emerged that have effectively reduced the excess deposition of extracellular matrix associated with fibrotic conditions. Novel treatments have recently been identified that hold promise as potential therapeutic agents for cardiovascular diseases associated with fibrosis, as well as other fibrotic conditions. The purpose of this review is to provide an overview of emerging antifibrotic agents that have shown encouraging results in preclinical or early clinical studies, but have not yet been approved for use in human disease. One of these agents is bone morphogenetic protein-7 (BMP7), which has beneficial effects in multiple models of fibrotic disease. Another approach discussed involves altering the levels of micro-RNA (miR) species, including miR-29 and miR-101, which regulate the expression of fibrosis-related gene targets. Further, the antifibrotic potential of agonists of the peroxisome proliferator-activated receptors will be discussed. Finally, evidence will be reviewed in support of the polypeptide hormone relaxin. Relaxin is long known for its extracellular remodeling properties in pregnancy, and is rapidly emerging as an effective antifibrotic agent in a number of organ systems. Moreover, relaxin has potent vascular and renal effects that make it a particularly attractive approach for the treatment of cardiovascular diseases. In each case, the mechanism of action and the applicability to various fibrotic diseases will be discussed.

Epigenetics and Liver Fibrosis

Liver fibrosis arises because prolonged injury combined with excessive scar deposition within hepatic parenchyma arising from overactive wound healing response mediated by activated myofibroblasts. Fibrosis is the common end point for any type of chronic liver injury including alcoholic liver disease, nonalcoholic fatty liver disease, viral hepatitis, and cholestatic liver diseases. Although genetic influences are important, it is epigenetic mechanisms that have been shown to orchestrate many aspects of fibrogenesis in the liver. New discoveries in the field are leading toward the development of epigenetic biomarkers and targeted therapies. This review considers epigenetic mechanisms as well as recent advances in epigenetic programming in the context of hepatic fibrosis.

Rosmarinic acid counteracts activation of hepatic stellate cells via inhibiting the ROS-dependent MMP-2 activity: Involvement of Nrf2 antioxidant system

Recently, oxidative stress is involved in hepatofibrogenesis. Matrix metalloproteinase-2 (MMP-2) is required for activation of hepatic stellate cells (HSCs) in response to reactive oxygen species (ROS). This study was designed to explore the hypothesis that the inhibitory effect of rosmarinic acid (RA) on HSCs activation might mainly result from its antioxidant capability by increasing the synthesis of glutathione (GSH) involved in nuclear factor kappa B (NF-κB)-dependent inhibition of MMP-2 activity. Here, we demonstrate that RA reverses activated HSCs to quiescent cells. Concomitantly, RA inhibits MMP-2 activity. RNA interference-imposed knockdown of NF-κB abolished down-regulation of MMP-2 by RA. RA-mediated inactivation of NF-κB could be blocked by the diphenyleneiodonium chloride (DPI; a ROS inhibitor). Conversely, transfection of dominant-negative (DN) mutant of extracellular signal-regulated kinases 2 (ERK2), c-Jun N-terminal kinase 1 (JNK1), or p38α kinase had no such effect. Simultaneously, RA suppresses ROS generation and lipid peroxidation (LPO) whereas increases cellular GSH in HSC-T6 cells. Furthermore, RA significantly increased antioxidant response element (ARE)-mediated luciferase activity, nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and catalytic subunits from glutamate cysteine ligase (GCLc) expression, but not modulatory subunits from GCL (GCLm). RA-mediated up-regulation of GClc is inhibited by the shRNA-induced Nrf2 knockdown. The knocking down of Nrf2 or buthionine sulfoximine (a GCL inhibitor) abolished RA-mediated inhibition of ROS. Collectively, these results provide novel insights into the mechanisms of RA as an antifibrogenic candidate in the prevention and treatment of liver fibrosis.

Baicalin ameliorates renal fibrosis via inhibition of transforming growth factor β1 production and downstream signal transduction

Previous studies have demonstrated the potential antifibrotic effects of baicalin in vitro, via examination of 21 compounds isolated from plants. However, its biological activity and underlying mechanisms of action in vivo remain to be elucidated. The present study aimed to evaluate the effect of baicalin on renal fibrosis in vivo, and the potential signaling pathways involved. A unilateral ureteral obstruction (UUO)‑induced renal fibrosis model was established using Sprague‑Dawley rats. Baicalin was administrated intraperitoneally every 2 days for 10 days. The degree of renal damage and fibrosis was investigated by histological assessment, and detection of fibronectin and collagen I mRNA expression levels. Epithelial‑mesenchymal transition (EMT) markers, transforming growth factor-β1 (TGF-β1) levels and downstream phosphorylation of mothers against decapentaplegic 2/3 (Smad2/3) were examined in vivo and in an NRK‑52E rat renal tubular cell line in vitro. Baicalin was demonstrated to markedly ameliorate renal fibrosis and suppress EMT, as evidenced by reduced interstitial collagen accumulation, decreased fibronectin and collagen I mRNA expression levels, upregulation of N‑ and E‑cadherin expression levels, and downregulation of α‑smooth muscle actin and vimentin expression. Furthermore, baicalin decreased TGF‑β1 expression levels in serum and kidney tissue following UUO, and suppressed Smad2/3 phosphorylation in rat kidney tissue. In vitro studies identified that baicalin may inhibit the phosphorylation of Smad2/3 under the same TGF‑β1 concentration. In conclusion, baicalin may protect against renal fibrosis, potentially via inhibition of TGF‑β1 production and its downstream signal transduction.

Positive feedback loop of YB-1 interacting with Smad2 promotes liver fibrosis

Y-box binding protein (YB-1), known as a multifunctional cellular protein in various biological processes, was recently reported to be associated with liver fibrosis. The critical role of TGF-β/Smad signaling pathway in stimulating the transcription of fibrotic genes in fibroblasts have already been identified, however, whether and how YB-1 modulated liver fibrosis via TGF-β/Smad signaling pathway remains largely unknown. In our previous study, we proved that ectopic TGF-β was associated with YB-1 expression. Herein, by combining in vitro experiments in LX2 human hepatic stellate cells and in vivo studies by building CCl4 based mice liver fibrosis model, we showed that YB-1 and p-YB-1 were upregulated in liver fibrosis tissue, and YB-1 promoted the deposition of excess extracellular matrix. Mechanistically, Smad2, a key member in TGF-β signaling pathway, acted as a transcription factor that triggered YB-1 promoter, while on the other hand, p-YB-1 stabilized Smad2 by attenuating its ubiquitination. Knockdown of Smad2 could reduce YB-1 expression, which in turn shorter the half time of Smad2. Furthermore, the serine102 residue of YB-1 both affected its binding and stabilizing activity to Smad2. These finding demonstrated that YB-1 and Smad2 played as a positive feedback loop in promoting liver fibrosis. In conclusion, TGF-β signaling pathway may influence liver fibrosis by incorporating with YB-1, indicating that YB-1 could be a potential target for therapies against liver fibrosis.

Epigenetics in fibrosis

Fibrosis is a common and important disease. It is a pathological state due to excessive scar formation mediated by an increase in activated fibroblasts that express alpha smooth muscle actin and copious amounts of extracellular matrix molecules. Epigenetics is an area of research that encompasses three main mechanisms: methylation, histone modifications to the tails of histones and also non-coding RNAs including long and short non-coding RNAs. These three mechanisms all seek to regulate gene expression without a change in the underlying DNA sequence. In recent years an explosion of research, aided by deep sequencing technology becoming available, has demonstrated a role for epigenetics in fibrosis, either organ specific like lung fibrosis or more widespread as in systemic sclerosis. While the great majority of epigenetic work in fibrosis is centered on histone codes, more recently the non-coding RNAs have been examined in greater detail. It is known that one modification can affect the other and cross-talk among all three adds a new layer of complexity. This review aims to examine the role of epigenetics in fibrosis, evaluating all three mechanisms, and to suggest possible areas where epigenetics could be targeted therapeutically.

Modified Adenovirus Reduces De Novo Peritoneal Adhesions in Rats and Limits Off-Target Transfection. Role of EZH2 in Adhesion Formation

AIM OF THE STUDY

Adenovector encoding tissue plasminogen activator (tPA) was shown to reduce experimental peritoneal adhesion. We investigated the targeting potential of our modified adenovector, its ability to reduce adhesions and the epigenetic role of histone methyltransferase EZH2 in adhesion formation.

MATERIALS AND METHODS

Control lacZ, nonmodified tPA or modified tPA vectors were instilled in the peritoneal cavity after injury in de novo adhesions or after lysis of adhesions in recurrent adhesions. Adhesion severity was scored and adhesions and liver tissues were examined for adenovirus E4 gene and tPA mRNA expression. Levels of tPA, plasminogen activator inhibitor-1 (PAI-1), transforming growth factor-β1 (TGF-β1), and EZH2 expression were measured.

RESULTS

E4 transcripts were detected in adhesions of nonmodified and modified and in livers of nonmodified but not in livers of modified de novo adhesions. Both nonmodified (p = 0.021) and modified vectors (p = 0.036) reduced the severity of de novo adhesions compared to lacZ vector. Levels of tPA in nonmodified (p = 0.021) and modified adhesions (p = 0.001) were elevated while PAI-1 (p = 0.013 and p = 0.001, respectively) and TGF-β1 levels (p = 0.002 and p = 0.016, respectively) were reduced compared with lacZ group. All vectors were not expressed in recurrent adhesions and severity score were not different among groups. EZH2 levels were elevated in de novo nontreated (p = 0.001) and was further increased in recurrent (p = 0.001) nontreated adhesions compared with noninjured peritoneum.

CONCLUSION

Modified adenovirus successfully targeted de novo adhesions but not liver tissues and reduced the severity of de novo adhesions. EZH2 is involved in the development and progression of peritoneal adhesions.

Rosmarinic acid inhibits inflammation and angiogenesis of hepatocellular carcinoma by suppression of NF-κB signaling in H22 tumor-bearing mice

The aim of this study was to explore the anti-tumor effect and therapeutic potential of rosmarinic acid (RA) in the treatment of hepatocellular carcinoma (HCC). RA at 75, 150 and 300 mg/kg was given to H22 tumor-bearing mice by intragastric administration once daily for 10 consecutive days. Levels of inflammatory and angiogenic factors, including interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), vascular endothelial growth factor (VEGF), and transforming growth factor-β (TGF-β) were measured by enzyme linked immunosorbent assays (ELISA). Protein levels of phosphorylated NF-κB p65 and p65 were detected by western blot. mRNA level of NF-κB p65 was analyzed by qRT-PCR. The results showed that RA could effectively suppress tumor growth with fewer toxic effects by regulating the secretion of cytokines associated with inflammation and angiogenesis, and suppressing the expression of NF-κB p65 in the xenograft microenvironment. Our findings unveil the possible anti-tumor mechanisms of RA and support RA as a potential drug for the treatment of HCC.

Naringin in Ganshuang Granule suppresses activation of hepatic stellate cells for anti-fibrosis effect by inhibition of mammalian target of rapamycin

A previous study has demonstrated that Ganshuang granule (GSG) plays an anti-fibrotic role partially by deactivation of hepatic stellate cells (HSCs). In HSCs activation, mammalian target of rapamycin (mTOR)-autophagy plays an important role. We attempted to investigate the role of mTOR-autophagy in anti-fibrotic effect of GSG. The cirrhotic mouse model was prepared to demonstrate the anti-fibrosis effect of GSG. High performance liquid chromatography (HPLC) analyses were used to identify the active component of GSG. The primary mouse HSCs were isolated and naringin was added into activated HSCs to observe its anti-fibrotic effect. 3-methyladenine (3-MA) and Insulin-like growth factor-1 (IGF-1) was added, respectively, into fully activated HSCs to explore the role of autophagy and mTOR. GSG played an anti-fibrotic role through deactivation of HSCs in cirrhotic mouse model. The concentration of naringin was highest in GSG by HPLC analyses and naringin markedly suppressed HSCs activation in vitro, which suggested that naringin was the main active component of GSG. The deactivation of HSCs caused by naringin was not because of the autophagic activation but mTOR inhibition, which was supported by the following evidence: first, naringin induced autophagic activation, but when autophagy was blocked by 3-MA, deactivation of HSCs was not attenuated or reversed. Second, naringin inhibited mTOR pathway, meanwhile when mTOR was activated by IGF-1, deactivation of HSCs was reversed. In conclusion, we have demonstrated naringin in GSG suppressed activation of HSCs for anti-fibrosis effect by inhibition of mTOR, indicating a potential therapeutic application for liver cirrhosis.

Baicalin attenuates bleomycin-induced pulmonary fibrosis via adenosine A2a receptor related TGF-β1-induced ERK1/2 signaling pathway

BACKGROUND

Baicalin has been reported to have anti-fibrosis effect; however, its mechanism still remains to be elucidated. Adenosine A2a receptor (A2aR) is a novel inflammation regulator, and transforming growth factor-β1 (TGF-β1)-induced extracellular signal regulated kinase1/2 (ERK1/2) signaling pathway plays an important role in idiopathic pulmonary fibrosis (IPF). This study was to explore the relationship of A2aR and TGF-β1-induced ERK1/2 in bleomycin (BLM)-induced pulmonary fibrosis in mice, and to investigate whether A2aR mediate the anti-fibrosis effect of Baicalin on BLM-induced pulmonary fibrosis.

METHODS

The A2aR-/- and A2aR+/+ mice were respectively divided into three groups: control group, model group, baicalin group. Pulmonary fibrosis was induced in mice of model groups by intratracheal instillation of bleomycin, and baicalin was administered in mice of baicalin groups daily for 28 days. Histopathological and ultrastructural changes of lung tissues were evaluated. Lung coefficient and the levels of hydroxyproline (HYP) in lung tissues were measured at the same time. The levels of serum TGF-β1 were measured by ELISA. The expression of TGF-β1, ERK1/2, p-ERK1/2 and A2aR were detected by western blot and immunohistochemical staining techniques.

RESULTS

Severe lung fibrosis was observed in the bleomycin-treated mice on day 28. The histopathological findings and collagen content of lung tissues were much severer/higher in A2aR-/- mice than in A2aR+/+ mice. We also showed that TGF-β1 and p-ERK1/2 were upregulated in bleomycin-treated mice and expressed higher in A2aR-/- mice compared to A2aR+/+ mice. Besides, bleomycin-treated A2aR+/+ mice had increased A2aR level in lungs. However, long-term treatment with baicalin in A2aR-/- and A2aR+/+ mice significantly ameliorated the histopathological changes in lungs. Moreover, Increased TGF-β1 and p-ERK1/2 expressions in bleomycin-treated A2aR-/- and A2aR+/+ mice were obviously diminished by baicalin. The baicalin-treated A2aR-/- mice had severer lung fibrosis and higher expressions of TGF-β1 and p-ERK1/2 than A2aR+/+ mice. Baicalin has also upregulated the expression of A2aR in A2aR+/+ mice.

CONCLUSIONS

Genetic inactivation of A2aR exacerbated the pathological processes of bleomycin-induced pulmonary fibrosis. Together, baicalin could inhibit BLM-induced pulmonary fibrosis by upregulating A2aR, suggesting A2aR as a therapeutic target of baicalin for the treatment of pulmonary fibrosis.

Scutellaria baicalensis, the golden herb from the garden of Chinese medicinal plants

Scutellaria baicalensis Georgi, or Chinese skullcap, has been widely used as a medicinal plant in China for thousands of years, where the preparation from its roots is called Huang-Qin. It has been applied in the treatment of diarrhea, dysentery, hypertension, hemorrhaging, insomnia, inflammation and respiratory infections. Flavones such as baicalin, wogonoside and their aglycones baicalein wogonin are the major bioactive compounds extracted from the root of S. baicalensis. These flavones have been reported to have various pharmacological functions, including anti-cancer, hepatoprotection, antibacterial and antiviral, antioxidant, anticonvulsant and neuroprotective effects. In this review, we focus on clinical applications and the pharmacological properties of the medicinal plant and the flavones extracted from it. We also describe biotechnological and metabolic methods that have been used to elucidate the biosynthetic pathways of the bioactive compounds in Scutellaria.

Evolving Insights on Metabolism, Autophagy, and Epigenetics in Liver Myofibroblasts

Liver myofibroblasts (MFB) are crucial mediators of extracellular matrix (ECM) deposition in liver fibrosis. They arise mainly from hepatic stellate cells (HSCs) upon a process termed “activation.” To a lesser extent, and depending on the cause of liver damage, portal fibroblasts, mesothelial cells, and fibrocytes may also contribute to the MFB population. Targeting MFB to reduce liver fibrosis is currently an area of intense research. Unfortunately, a clog in the wheel of antifibrotic therapies is the fact that although MFB are known to mediate scar formation, and participate in liver inflammatory response, many of their molecular portraits are currently unknown. In this review, we discuss recent understanding of MFB in health and diseases, focusing specifically on three evolving research fields: metabolism, autophagy, and epigenetics. We have emphasized on therapeutic prospects where applicable and mentioned techniques for use in MFB studies. Subsequently, we highlighted uncharted territories in MFB research to help direct future efforts aimed at bridging gaps in current knowledge.

Characterization of hepatic stellate cells, portal fibroblasts, and mesothelial cells in normal and fibrotic livers

BACKGROUND & AIMS

Contribution of hepatic stellate cells (HSCs), portal fibroblasts (PFs), and mesothelial cells (MCs) to myofibroblasts is not fully understood due to insufficient availability of markers and isolation methods. The present study aimed to isolate these cells, characterize their phenotypes, and examine their contribution to myofibroblasts in liver fibrosis.

METHODS

Liver fibrosis was induced in Collagen1a1-green fluorescent protein (Col1a1(GFP)) mice by bile duct ligation (BDL), 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) diet, or CCl4 injections. Combining vitamin A (VitA) lipid autofluorescence and expression of GFP and glycoprotein M6a (GPM6A), we separated HSCs, PFs, and MCs from normal and fibrotic livers by fluorescence-activated cell sorting (FACS).

RESULTS

Normal Col1a1(GFP) livers broadly expressed GFP in HSCs, PFs, and MCs. Isolated VitA+ HSCs expressed reelin, whereas VitA-GFP+GPM6A- PFs expressed ectonucleoside triphosphate diphosphohydrolase-2 and elastin. VitA-GFP+GPM6A+ MCs expressed keratin 19, mesothelin, and uroplakin 1b. Transforming growth factor (TGF)-β1 treatment induced the transformation of HSCs, PFs, and MCs into myofibroblasts in culture. TGF-β1 suppressed cyclin D1 mRNA expression in PFs but not in HSCs and MCs. In biliary fibrosis, PFs adjacent to the bile duct expressed α-smooth muscle actin. FACS analysis revealed that HSCs are the major source of GFP+ myofibroblasts in the injured Col1a1(GFP) mice after DDC or CCl4 treatment. Although PFs partly contributed to GFP+ myofibroblasts in the BDL model, HSCs were still dominant source of myofibroblasts.

CONCLUSION

HSCs, PFs, and MCs have distinct phenotypes, and PFs partly contribute to myofibroblasts in the portal triad in biliary fibrosis.

A specialized flavone biosynthetic pathway has evolved in the medicinal plant, Scutellaria baicalensis

Wogonin and baicalein are bioactive flavones in the popular Chinese herbal remedy Huang-Qin (Scutellaria baicalensis Georgi). These specialized flavones lack a 4'-hydroxyl group on the B ring (4'-deoxyflavones) and induce apoptosis in a wide spectrum of human tumor cells in vitro and inhibit tumor growth in vivo in different mouse tumor models. Root-specific flavones (RSFs) from Scutellaria have a variety of reported additional beneficial effects including antioxidant and antiviral properties. We describe the characterization of a new pathway for the synthesis of these compounds, in which pinocembrin (a 4'-deoxyflavanone) serves as a key intermediate. Although two genes encoding flavone synthase II (FNSII) are expressed in the roots of S. baicalensis, FNSII-1 has broad specificity for flavanones as substrates, whereas FNSII-2 is specific for pinocembrin. FNSII-2 is responsible for the synthesis of 4'-deoxyRSFs, such as chrysin and wogonin, wogonoside, baicalein, and baicalin, which are synthesized from chrysin. A gene encoding a cinnamic acid-specific coenzyme A ligase (SbCLL-7), which is highly expressed in roots, is required for the synthesis of RSFs by FNSII-2, as demonstrated by gene silencing. A specific isoform of chalcone synthase (SbCHS-2) that is highly expressed in roots producing RSFs is also required for the synthesis of chrysin. Our studies reveal a recently evolved pathway for biosynthesis of specific, bioactive 4'-deoxyflavones in the roots of S. baicalensis.

Hepatoprotective Effects of Chinese Medicinal Herbs: A Focus on Anti-Inflammatory and Anti-Oxidative Activities

The liver is intimately connected to inflammation, which is the innate defense system of the body for removing harmful stimuli and participates in the hepatic wound-healing response. Sustained inflammation and the corresponding regenerative wound-healing response can induce the development of fibrosis, cirrhosis and eventually hepatocellular carcinoma. Oxidative stress is associated with the activation of inflammatory pathways, while chronic inflammation is found associated with some human cancers. Inflammation and cancer may be connected by the effect of the inflammation-fibrosis-cancer (IFC) axis. Chinese medicinal herbs display abilities in protecting the liver compared to conventional therapies, as many herbal medicines have been shown as effective anti-inflammatory and anti-oxidative agents. We review the relationship between oxidative stress and inflammation, the development of hepatic diseases, and the hepatoprotective effects of Chinese medicinal herbs via anti-inflammatory and anti-oxidative mechanisms. Moreover, several Chinese medicinal herbs and composite formulae, which have been commonly used for preventing and treating hepatic diseases, including Andrographis Herba, Glycyrrhizae Radix et Rhizoma, Ginseng Radix et Rhizoma, Lycii Fructus, Coptidis Rhizoma, curcumin, xiao-cha-hu-tang and shi-quan-da-bu-tang, were selected for reviewing their hepatoprotective effects with focus on their anti-oxidative and ant-inflammatory activities. This review aims to provide new insight into how Chinese medicinal herbs work in therapeutic strategies for liver diseases.

Anti-Hypertensive Herbs and Their Mechanisms of Action: Part II

Traditional medicine has a history extending back to thousands of years, and during the intervening time, man has identified the healing properties of a very broad range of plants. Globally, the use of herbal therapies to treat and manage cardiovascular disease (CVD) is on the rise. This is the second part of our comprehensive review where we discuss the mechanisms of plants and herbs used for the treatment and management of high blood pressure. Similar to the first part, PubMed and ScienceDirect databases were utilized, and the following keywords and phrases were used as inclusion criteria: hypertension, high blood pressure, herbal medicine, complementary and alternative medicine, endothelial cells, nitric oxide (NO), vascular smooth muscle cell (VSMC) proliferation, hydrogen sulfide, nuclear factor kappa-B (NF-κB), oxidative stress, and epigenetics/epigenomics. Each of the aforementioned keywords was co-joined with plant or herb in question, and where possible with its constituent molecule(s). This part deals in particular with plants that are used, albeit less frequently, for the treatment and management of hypertension. We then discuss the interplay between herbs/prescription drugs and herbs/epigenetics in the context of this disease. The review then concludes with a recommendation for more rigorous, well-developed clinical trials to concretely determine the beneficial impact of herbs and plants on hypertension and a disease-free living.

Role of TGF-β signaling in differentiation of mesothelial cells to vitamin A-poor hepatic stellate cells in liver fibrosis

Mesothelial cells (MCs) form a single layer of the mesothelium and cover the liver surface. A previous study demonstrated that, upon liver injury, MCs migrate inward from the liver surface and give rise to hepatic stellate cells (HSCs) in biliary fibrosis induced by bile duct ligation (BDL) or myofibroblasts in CCl4-induced fibrosis. The present study analyzed the role of transforming growth factor-β (TGF-β) signaling in mesothelial-mesenchymal transition (MMT) and the fate of MCs during liver fibrosis and its regression. Deletion of TGF-β type II receptor (Tgfbr2) gene in cultured MCs suppressed TGF-β-mediated myofibroblastic conversion. Conditional deletion of Tgfbr2 gene in MCs reduced the differentiation of MCs to HSCs and myofibroblasts in the BDL and CCl4 models, respectively, indicating that the direct TGF-β signaling in MCs is responsible to MMT. After BDL and CCl4 treatment, MC-derived HSCs and myofibroblasts were distributed near the liver surface and the thickness of collagen was increased in Glisson's capsule beneath the liver surface. Fluorescence-activated cell sorting analysis revealed that MC-derived HSCs and myofibroblasts store little vitamin A lipids and have fibrogenic phenotype in the fibrotic livers. MCs contributed to 1.4 and 2.0% of activated HSCs in the BDL and CCl4 models, respectively. During regression of CCl4-induced fibrosis, 20% of MC-derived myofibroblasts survived in the liver and deactivated to vitamin A-poor HSCs. Our data indicate that MCs participate in capsular fibrosis by supplying vitamin A-poor HSCs during a process of liver fibrosis and regression.

Preclinical Models for Investigation of Herbal Medicines in Liver Diseases: Update and Perspective

Liver disease results from a dynamic pathological process associated with cellular and genetic alterations, which may progress stepwise to liver dysfunction. Commonly, liver disease begins with hepatocyte injury, followed by persistent episodes of cellular regeneration, inflammation, and hepatocyte death that may ultimately lead to nonreversible liver failure. For centuries, herbal remedies have been used for a variety of liver diseases and recent studies have identified the active compounds that may interact with liver disease-associated targets. Further study on the herbal remedies may lead to the formulation of next generation medicines with hepatoprotective, antifibrotic, and anticancer properties. Still, the pharmacological actions of vast majority of herbal remedies remain unknown; thus, extensive preclinical studies are important. In this review, we summarize progress made over the last five years of the most commonly used preclinical models of liver diseases that are used to screen for curative herbal medicines for nonalcoholic fatty liver disease, liver fibrosis/cirrhosis, and liver. We also summarize the proposed mechanisms associated with the observed liver-protective, antifibrotic, and anticancer actions of several promising herbal medicines and discuss the challenges faced in this research field.

A novel strategy of profiling the mechanism of herbal medicines by combining network pharmacology with plasma concentration determination and affinity constant measurement

Herbal medicines have long been widely used in the treatment of various complex diseases in China.

Baicalin promotes embryo adhesion and implantation by upregulating fucosyltransferase IV (FUT4) via Wnt/beta-catenin signaling pathway

Glycosylation plays a significant role in determining the receptivity of the uterine endometrium to embryo. Fucosyltransferase IV (FUT4) is expressed stage-specifically in the uterine endometrium of mammalians, and considered as a marker of the endometrial receptivity. Baicalin, a monomer of flavonoids, is known to have functions in improving reproduction. However, the mechanism by which baicalin regulates the expression of FUT4 in embryo-endometrium adhesion remains unclear. Our results showed that baicalin significantly increased FUT4 mRNA and protein expression levels both in human endometrial cells and mouse endometrial tissue, and consistently elevated embryo adhesion rate during implantation in vitro and embryonic implantation competence in pregnant mouse. This study suggests that baicalin facilitates endometrial reproduction via elevating FUT4 expression through Wnt/β-catenin signaling pathway.

Potent natural products and herbal medicines for treating liver fibrosis

Liver fibrosis is a wound-healing response to chronic liver injury characterized by progressive inflammation and deposition of extracellular matrix components. The pathological condition of liver fibrosis involves secretion of extracellular matrix proteins and formation of scar tissue. The major regulators involved in hepatic fibrogenesis are the transforming growth factor (TGF)-β1/SMAD and toll-like receptor 4 (TLR4)-initiated myeloid differentiation primary response 88 gene (MyD88)/NF-ĸB cell signaling pathways. This article reviews natural products and herbal medicines that have demonstrated activity against liver fibrosis through different mechanisms of action, including anti-hepatitis B and C virus activity, anti-inflammation, inhibition of cytokine production and nuclear receptor activation, and free radical scavenging.

Rosmarinic acid exerts an antiosteoporotic effect in the RANKL-induced mouse model of bone loss by promotion of osteoblastic differentiation and inhibition of osteoclastic differentiation

SCOPE

Bone homeostasis is ensured by the balance between bone formation and resorption. Thus, control of the recruitment, proliferation, and differentiation of bone cells is essential to maintain bone mass. The aim of this study was to elucidate the effects of rosmarinic acid as a potential therapeutic agent on bone metabolism using bone cells and a mouse model.

METHODS AND RESULTS

Rosmarinic acid increased alkaline phosphatase activity and induced mineralization in osteoblasts. Addition of rosmarinic acid to cultures of calvarial osteoblastic cells prepared from T-cell factor/β-catenin TOP-GAL mutant mice strongly induced the expression of LacZ and promoted stabilization of β-catenin in the cytoplasm of ST2 cells, suggesting that rosmarinic acid affects the canonical Wnt signaling pathway. Moreover, rosmarinic acid inhibited not only osteoclast formation in cocultures of mouse bone marrow cells and osteoblasts, but also receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastic differentiation in bone marrow-derived macrophages. RANKL-induced p38 mitogen-activated protein kinase and the expression of nuclear factor of activated T cell, c-Jun, and c-Fos were inhibited by rosmarinic acid in bone marrow macrophages. Finally, we confirmed that rosmarinic acid improved bone mass in a soluble RANKL-induced bone loss mouse model.

CONCLUSION

Rosmarinic acid has dual regulatory effects on bone metabolism and may control the bone functions by controlling osteoblastic and osteoclastic differentiation.

Mutant MMP-9 and HGF gene transfer enhance resolution of CCl4-induced liver fibrosis in rats: role of ASH1 and EZH2 methyltransferases repression

Hepatocyte growth factor (HGF) gene transfer inhibits liver fibrosis by regulating aberrant cellular functions, while mutant matrix metalloproteinase-9 (mMMP-9) enhances matrix degradation by neutralizing the elevated tissue inhibitor of metalloproteinase-1 (TIMP-1). It was shown that ASH1 and EZH2 methyltransferases are involved in development of liver fibrosis; however, their role in the resolution phase of liver fibrosis has not been investigated. This study evaluated the role of ASH1 and EZH2 in two mechanistically different therapeutic modalities, HGF and mMMP-9 gene transfer in CCl₄ induced rat liver fibrosis. Liver fibrosis was induced in rats with twice a week intraperitoneal injection of CCl₄ for 8 weeks. Adenovirus vectors encoding mMMP-9 or HGF genes were injected through tail vein at weeks six and seven and were sacrificed one week after the second injection. A healthy animal group was likewise injected with saline to serve as a negative control. Rats treated with mMMP-9 showed significantly lower fibrosis score, less Sirius red stained collagen area, reduced hydroxyproline and ALT concentration, decreased transforming growth factor beta 1 (TGF-β1) mRNA and lower labeling indices of α smooth muscle actin (α-SMA) and proliferating cell nuclear antigen (PCNA) stained cells compared with HGF- or saline-treated rats. Furthermore, TIMP-1 protein expression in mMMP-9 group was markedly reduced compared with all fibrotic groups. ASH1 and EZH2 protein expression was significantly elevated in fibrotic liver and significantly decreased in mMMP-9- and HGF-treated compared to saline-treated fibrotic livers with further reduction in the mMMP-9 group. Conclusion: Gene transfer of mMMP-9 and HGF reduced liver fibrosis in rats. ASH1 and EZH2 methyltransferases are significantly reduced in mMMP-9 and HGF treated rats which underlines the central role of these enzymes during fibrogenesis. Future studies should evaluate the role of selective pharmacologic inhibitors of ASH1 and EZH2 in resolution of liver fibrosis.

The mechanisms of HSC activation and epigenetic regulation of HSCs phenotypes

Epigenetics is a dynamically expanding field of science entailing numerous regulatory mechanisms controlling changes of gene expression in response to environmental factors. Over the recent years there has been a great interest in epigenetic marks as a potential diagnostic and prognostic tool or future target for treatment of various human diseases. There is an increasing body of published research to suggest that epigenetic events regulate progression of chronic liver disease. Experimental manipulation of epigenetic signatures such as DNA methylation, histone acetylation / methylation and the activities of proteins that either annotate or interpret these epigenetic marks can have profound effects on the activation and phenotype of HSC, key cells responsible for onset and progression of liver fibrosis. This review presents recent advances in epigenetic alterations, which could provide mechanistic insight into the pathogenesis of chronic liver disease and provide novel clinical applications.

New Approaches for Studying Alcoholic Liver Disease

Alcoholic liver disease (ALD) is major cause of chronic liver injury which results in liver fibrosis and cirrhosis. According to the surveillance report published by the National Institute on Alcohol Abuse and Alcoholism, liver cirrhosis is the 12th leading cause of death in the United States with 48 % of these deaths being attributed to excessive alcohol consumption. ALD includes a spectrum of disorders from simple steatosis to steatohepatitis, fibrosis, and hepatocellular carcinoma. Several mechanisms play a critical role in the pathogenesis of ALD. These include ethanol-induced oxidative stress and depletion of glutathione, pathological methionine metabolism, increased gut permeability and release of endotoxins into the portal blood, recruitment and activation of inflammatory cells including bone marrow-derived and liver resident macrophages (Kupffer cells). Chronic alcohol consumption results in liver damage and activation of hepatic stellate cells (HSCs) and myofibroblasts, leading to liver fibrosis. Here we discuss the current view on factors that are specific for different stages of ALD and those that regulate its progression, including cytokines and chemokines, alcohol-responsive intracellular signaling pathways, and transcriptional factors. We also review recent studies demonstrating that alcohol-mediated changes can be regulated on an epigenetic level, including microRNAs. Finally, we discuss the reversibility of liver fibrosis and inactivation of HSCs as a potential strategy for treating alcohol-induced liver damage.

Extracellular matrix and liver disease

SIGNIFICANCE

The extracellular matrix (ECM) is a dynamic microenvironment that undergoes continuous remodeling, particularly during injury and wound healing. Chronic liver injury of many different etiologies such as viral hepatitis, alcohol abuse, drug-induced liver injury, obesity and insulin resistance, metabolic disorders, and autoimmune disease is characterized by excessive deposition of ECM proteins in response to persistent liver damage.

CRITICAL ISSUES

This review describes the main collagenous and noncollagenous components from the ECM that play a significant role in pathological matrix deposition during liver disease. We define how increased myofibroblasts (MF) from different origins are at the forefront of liver fibrosis and how liver cell-specific regulation of the complex scarring process occurs.

RECENT ADVANCES

Particular attention is paid to the role of cytokines, growth factors, reactive oxygen species, and newly identified matricellular proteins in the regulation of fibrillar type I collagen, a field to which our laboratory has significantly contributed over the years. We compile data from recent literature on the potential mechanisms driving fibrosis resolution such as MF' apoptosis, senescence, and reversal to quiescence.

FUTURE DIRECTIONS

We conclude with a brief description of how epigenetics, an evolving field, can regulate the behavior of MF and of how new "omics" tools may advance our understanding of the mechanisms by which the fibrogenic response to liver injury occurs.

Regulation of activation and proliferation of hepatic stellate cells through the Wnt signaling pathway: Implications for treatment of liver fibrosis

Liver fibrosis, a reversible pathological condition occurring after chronic liver injury, is closely associated with the activation and proliferation of hepatic stellate cells (HSCs). Several studies have demonstrated that the Wnt signaling pathway is involved in the activation of HSCs, and then contributes to the occurrence and development of liver fibrosis. Thus, the Wnt signaling pathway and HSCs are considered to be the valid targets for the treatment of liver fibrosis. In recent years, domestic and international scholars have carried on many studies on the regulation of the Wnt signaling pathway and HSCs, trying to find out effective antifibrotic therapies. A large number of studies have shown that regulating HSCs can play a positive role in the treatment of liver fibrosis through the Wnt signaling pathway. On the basis of the relationship among the Wnt signaling pathway, HSCs and liver fibrosis, this review mainly summarizes the latest progress in the study of strategies for regulating HSCs through the Wnt signaling pathway and discusses the implications for the treatment of liver fibrosis.

The types of hepatic myofibroblasts contributing to liver fibrosis of different etiologies

Liver fibrosis results from dysregulation of normal wound healing, inflammation, activation of myofibroblasts, and deposition of extracellular matrix (ECM). Chronic liver injury causes death of hepatocytes and formation of apoptotic bodies, which in turn, release factors that recruit inflammatory cells (neutrophils, monocytes, macrophages, and lymphocytes) to the injured liver. Hepatic macrophages (Kupffer cells) produce TGFβ1 and other inflammatory cytokines that activate Collagen Type I producing myofibroblasts, which are not present in the normal liver. Secretion of TGFβ1 and activation of myofibroblasts play a critical role in the pathogenesis of liver fibrosis of different etiologies. Although the composition of fibrogenic myofibroblasts varies dependent on etiology of liver injury, liver resident hepatic stellate cells and portal fibroblasts are the major source of myofibroblasts in fibrotic liver in both experimental models of liver fibrosis and in patients with liver disease. Several studies have demonstrated that hepatic fibrosis can reverse upon cessation of liver injury. Regression of liver fibrosis is accompanied by the disappearance of fibrogenic myofibroblasts followed by resorption of the fibrous scar. Myofibroblasts either apoptose or inactivate into a quiescent-like state (e.g., stop collagen production and partially restore expression of lipogenic genes). Resolution of liver fibrosis is associated with recruitment of macrophages that secrete matrix-degrading enzymes (matrix metalloproteinase, collagenases) and are responsible for fibrosis resolution. However, prolonged/repeated liver injury may cause irreversible crosslinking of ECM and formation of uncleavable collagen fibers. Advanced fibrosis progresses to cirrhosis and hepatocellular carcinoma. The current review will summarize the role and contribution of different cell types to populations of fibrogenic myofibroblasts in fibrotic liver.

Nuclear receptors and epigenetic regulation: opportunities for nutritional targeting and disease prevention

Posttranslational modifications of histones, alterations in the recruitment and functions of non-histone proteins, DNA methylation, and changes in expression of noncoding RNAs contribute to current models of epigenetic regulation. Nuclear receptors (NRs) are a group of transcription factors that, through ligand-binding, act as sensors to changes in nutritional, environmental, developmental, pathophysiologic, and endocrine conditions and drive adaptive responses via gene regulation. One mechanism through which NRs direct gene expression is the assembly of transcription complexes with cofactors and coregulators that possess chromatin-modifying properties. Chromatin modifications can be transient or become part of the cellular "memory" and contribute to genomic imprinting. Because many food components bind to NRs, they can ultimately influence transcription of genes associated with biologic processes, such as inflammation, proliferation, apoptosis, and hormonal response, and alter the susceptibility to chronic diseases (e.g., cancer, diabetes, obesity). The objective of this review is to highlight how NRs influence epigenetic regulation and the relevance of dietary compound-NR interactions in human nutrition and for disease prevention and treatment. Identifying gene targets of unliganded and bound NRs may assist in the development of epigenetic maps for food components and dietary patterns. Progress in these areas may lead to the formulation of disease-prevention models based on epigenetic control by individual or associations of food ligands of NRs.

Pigment epithelium-derived factor 34-mer peptide prevents liver fibrosis and hepatic stellate cell activation through down-regulation of the PDGF receptor

Pigment epithelium-derived factor (PEDF) has been shown previously to prevent liver fibrosis and hepatic stellate cell (HSC) activation. By investigating the functional domains in PEDF, we identified a 34-mer peptide (residues Asp44-Asn77) that harbors the same function as the full-length PEDF protein. Not only did the 34-mer suppress the development of fibrosis in carbon tetrachloride (CCl4)-treated mouse liver but it also upregulated peroxisome proliferator-activated receptor-gamma (PPARγ) expression in HSCs in vivo. Platelet-derived growth factor (PDGF) plays a crucial role on the process of HSC activation in response to liver damage. The 34-mer suppressed PDGF-induced cell proliferation and expression of myofibroblastic marker proteins in primary rat HSC culture, increased the levels of PPARγ mRNA and protein in a dose-dependent manner and markedly reduced the level of active β-catenin protein, an HSC activating factor, in HSC-T6 cells. Similarly, IWR-1, an inhibitor of the Wnt response, displayed the same effect as the 34-mer in preventing HSC-T6 activation. The Wnt signaling-mediated PPARγ suppression was abolished by both the IWR-1 inhibitor and a small interfering RNA (siRNA) targeting β-catenin and the Wnt coreceptor, LRP6. Both PEDF and the 34-mer down-regulated PDGF receptor-α/β expression and blocked the PDGF-induced phosphorylation of Akt and ERK. Moreover, the inhibitory effect on PDGF receptor expression was abolished by PPARγ antagonists and PPARγ siRNA. Our observations indicate that the PEDF-derived 34-mer peptide can mimic PEDF in attenuating HSC activation. Investigation of this 34-mer peptide led to the identification of a signaling mechanism involving PPARγ induction, suppression of Wnt/β-catenin signaling and down-regulation of the PDGF receptor-α/β.

Precision-cut liver slices as a model for the early onset of liver fibrosis to test antifibrotic drugs

Induction of fibrosis during prolonged culture of precision-cut liver slices (PCLS) was reported. In this study, the use of rat PCLS was investigated to further characterize the mechanism of early onset of fibrosis in this model and the effects of antifibrotic compounds. Rat PCLS were incubated for 48h, viability was assessed by ATP and gene expression of PDGF-B and TGF-β1 and the fibrosis markers Hsp47, αSma and Pcol1A1 and collagen1 protein expressions were determined. The effects of the antifibrotic drugs imatinib, sorafenib and sunitinib, PDGF-pathway inhibitors, and perindopril, valproic acid, rosmarinic acid, tetrandrine and pirfenidone, TGFβ-pathway inhibitors, were determined. After 48h of incubation, viability of the PCLS was maintained and gene expression of PDGF-B was increased while TGF-β1 was not changed. Hsp47, αSma and Pcol1A1 gene expressions were significantly elevated in PCLS after 48h, which was further increased by PDGF-BB and TGF-β1. The increased gene expression of fibrosis markers was inhibited by all three PDGF-inhibitors, while TGFβ-inhibitors showed marginal effects. The protein expression of collagen 1 was inhibited by imatinib, perindopril, tetrandrine and pirfenidone. In conclusion, the increased gene expression of PDGF-B and the down-regulation of fibrosis markers by PDGF-pathway inhibitors, together with the absence of elevated TGF-β1 gene expression and the limited effect of the TGFβ-pathway inhibitors, indicated the predominance of the PDGF pathway in the early onset of fibrosis in PCLS. PCLS appear a useful model for research of the early onset of fibrosis and for testing of antifibrotic drugs acting on the PDGF pathway.

Scutellariae radix suppresses LPS-induced liver endothelial cell activation and inhibits hepatic stellate cell migration

ETHNOPHARMACOLOGICAL RELEVANCE

Liver fibrosis is the result of long-term liver damage and the wound-healing process, in which the hepatic stellate cell (HSC) plays a crucial role during fibrogenesis. The liver sinusoidal endothelial cell (LSEC) is a liver-resident scavenger, contributing to sinusoidal remodeling, HSC activation and liver fibrosis. Lipopolysaccharide (LPS) causes an inflammatory reaction associated with portal circulation and LSECs signaling. Scutellariae radix, the root of Scutellaria baicalensis Georgi, is a Chinese herb widely used for liver diseases. However, its effect on LSEC activation and HSC migration in liver fibrosis has not been investigated yet.

AIM OF THIS STUDY

LPS-induced rat LSEC (rLSEC) activation was used as a model to screen and explore the active components of Scutellariae radix. The anti-fibrotic effect of Scutellariae radix on rLSEC activation and rHSC migration was further investigated.

MATERIALS AND METHODS

LPS-induced rLSEC mRNA expression, including VEGF, VEGFR, MCP-1, and TGF-β1, were examined by real-time PCR analyses. MCP-1 protein levels were measured by an ELISA kit. rLSEC conditioned medium on rHSC migration was measured by wound-healing assay and transwell chemoattraction assay.

RESULTS

Results showed LPS-induced rLSEC activation with upregulated MCP-1 mRNA and protein expressions, and that rLSEC-condition medium enhanced rHSC migration. Both baicalein and wogonin from the active subfraction significantly reduced MCP-1 expression, but only baicalein markedly inhibited rHSC migration in rLSEC conditioned medium.

CONCLUSION

This study demonstrated that Scutellariae radix attenuates LPS-induced rLSEC activation and HSC migration with downregulation of MCP-1 expression. The results provide supporting evidence that Scutellariae radix may be beneficial for the amelioration of liver fibrosis.

Inhibitory effect of baicalin on iNOS and NO expression in intestinal mucosa of rats with acute endotoxemia

The mechanism by which baicalin modulated the expression of inducible nitric oxide synthase (iNOS) and nitric oxide (NO) in the mucosa of distal ileum was investigated in a rat model of acute endo-toxemia induced by intraperitoneal injection of bacterial lipopolysaccharide (LPS). The experiment demonstrated that LPS upregulated iNOS mRNA and protein expression as well as NO produc-tion (measured as the stable degradation production, nitrites). LPS not only increased toll-like receptor 4 (TLR4) and peroxisome proliferator-activated receptor gamma (PPARγ) content, but also activated p38 and activating transcription factor 2 (ATF2) and inactivated PPARγ via phosphorylation. Inhibition of p38 signalling pathway by chemical inhibitor SB202190 and small interfering RNA (siRNA) ameliorated LPS-induced iNOS generation, while suppression of PPARγ pathway by SR-202 boosted LPS-elicited iNOS expression. Baicalin treatment (I) attenuated LPS-induced iNOS mRNA and protein as well as nitrites generation, and (II) ameliorated LPS-elicited TLR4 and PPARγ production, and (III) inhibited p38/ATF2 phosphorylation leading to suppression of p38 signalling, and (IV) prevented PPARγ from phosphorylation contributing to maintainence of PPARγ bioactivity. However, SR-202 co-treatment (I) partially abrogated the inhibitory effect of baicalin on iNOS mRNA expression, and (II) partially reversed baicalin-inhibited p38 phosphorylation. In summary, baicalin could ameliorate LPS-induced iNOS and NO overproduction in mucosa of rat terminal ileum via inhibition of p38 signalling cascade and activation of PPARγ pathway. There existed a interplay between the two signalling pathways.

Epigenetic modifications as new targets for liver disease therapies

An important discovery from the human genome mapping project was that it is comprised of a surprisingly low number of genes,with recent estimates suggesting they are as few as 25,000 [1].This supported an alternative hypothesis that our complexity in comparison with lower order species is likely to be determined by regulatory mechanisms operating at levels above the fundamental DNA sequences of the genome [2]. One set of mechanisms that dictate tissue and cellular complexity can be described by the overarching term "epigenetics". In the 1940s, Conrad Waddington described epigenetics as "the branch of biology which studies the causal interactions between genes and their products which bring the phenotype into being". Today we understand epigenetics as a gene regulatory system comprised of 3 major mechanisms including DNA modifications (e.g., methylation), use of histone variants and post-translational modifications of the amino acid tails of histones and non-coding RNAs of which microRNAs are the best characterized [3,4]. Together, these mechanisms orchestrate numerous sets of chemical reactions that switch parts of the genome on and off at specific times and locations.Epigenetic marks, or the epigenome, exhibit a high degree of cellular-specificity and developmental or environmentally driven dynamic plasticity. Due to being at the interface between genome and the environment, the epigenome evolves at a very high rate compared to genetic mutations. Indeed, the differences in the epigenome account for most of the phenotypic uniqueness between closely related species, especially primates. More interestingly,the epigenetic changes, or epimutations, within an individual are not only maintained over cellular generations, but may also be transmitted between generations, such that adaptive epimutations generated in response to a particular environmental cue can influence phenotypes in our children and grandchildren [5].