Cyclooxygenase 2 (COX2)-prostanoid pathway and liver diseases

The role of COX2 deficiency attenuates cardiac damage in acute myocardial infarction

Cardiac cell damage frequently occurs as a consequence of acute myocardial infarction (AMI), a critical complication of coronary atherosclerotic heart disease. There is an escalating recognition of the association between COX2 and myocardial damage induced by ischemia. The objective of this study is to investigate the inhibitory effect of the COX2 on cardiomyocyte damage in the context of AMI. To create an AMI model, mice with the genetic background of wild-type C57BL6/J (WT) and COX2-/- mice were utilized. The left anterior descending (LAD) coronary artery in their hearts was obstructed, and subsequent assessment of hemodynamic parameters and heart function was conducted. Notably, increased levels of COX2 were observed in AMI mice. Through correlational analysis between COX2 expression and cardiac function following AMI, it was revealed that COX2 knockout mice had smaller infarct sizes, better cardiac performance, and suppressed levels of reactive oxygen species (ROS) compared to WT mice. Additionally, we discovered that COX2 knockout mice exhibited significantly higher mRNA levels of smooth muscle actin, collagen I, and collagen III than normal mice with AMI. Conversely, the levels of superoxide dismutase (SOD), malondialdehyde (MDA) were higher but iron content was decreased in COX2 knockout mice compared to normal mice with AMI.In summary, our research demonstrates that the downregulation of COX2 enhances cardiac tissue recovery in the context of AMI.

Coleus vettiveroides ethanolic root extract protects against thioacetamide-induced acute liver injury in rats

Acute liver injury is caused by various factors, including oxidative stress and inflammation. Coleus vettiveroides, an ayurvedic medicinal plant, is known to possess antioxidant, antibacterial, and antidiabetic properties. In this current study, we investigated the protective effect of C. vettiveroides ethanolic root extract (CVERE) against thioacetamide (TAA)-induced acute liver injury in rats. A single dose of TAA (300 mg/kg, b.w., i.p.) was administered to induce acute liver injury. The treatment groups of rats were concurrently treated with CVERE (125 and 250 mg/kg, b.w., p.o.) and silymarin (100 mg/kg, b.w., p.o.), respectively. After 24 h of the experimental period, TAA-induced liver injury was confirmed by increased activity of serum transaminases and malondialdehyde levels in liver tissue, decreased levels of antioxidants, upregulated expression of the inflammatory marker gene, and altered liver morphology. Whereas CVERE simultaneous treatment inhibited hepatic injury and prevented the elevation of serum aspartate and alanine transaminases, alkaline phosphatase, and lactate dehydrogenase activities. CVERE attenuated TAA-induced oxidative stress by suppressing lipid peroxidation and restoring antioxidants such as superoxide dismutase, catalase, and reduced glutathione. Further, CVERE treatment was found to inhibit nuclear factor κB-mediated inflammatory signaling, as indicated by downregulated pro-inflammatory cytokines including tumor necrosis factor-α and interleukin-1β. Our findings suggest that CVERE prevents TAA-induced acute liver injury by targeting oxidative stress and inflammation.

Extract of Jasminum grandiflorum L. alleviates CCl4-induced liver injury by decreasing inflammation, oxidative stress and hepatic CYP2E1 expression in mice

Jasminum grandiflorum L. (JG) is a medicinal plant containing many bioactive ingredients. Herein, we analyzed the effects of four different extracts and two compounds of JG on acute liver injury caused by carbon tetrachloride (CCl₄) and underlying molecular mechanisms. 7 weeks old C57BL/6 male mice were used to establish a liver injury model by injecting with 1% CCl₄, 10 mL/kg ip. Four different extracts and two compounds of JG were given to mice by gavage for 3 days. Clinical and histological chemistry assays were performed to assess liver injury. Moreover, hepatic oxidative stress and inflammation related markers were determined by immunohistochemistry and western blotting. As a result, JG extracts and two functional components showed different degree of protect effects against CCl₄-induced liver injury by the decrease of elevated serum transaminases and liver index, and the attenuation of histopathological changes in mice, among which JG extracted with petroleum ether (PET) had the most significant effect. In addition, PET remarkably alleviated hepatic oxidative stress and inflammation. Further studies revealed that PET significantly inhibited the TNF-α expression, signal pathway expression, NF-κB p65 and inflammatory factors IL-1β and IL-6 expression in CCl₄-induced liver injury mice. Nevertheless, hydroxytyrosol (HT) alleviated liver injury by reducing oxidative stress. Apart from PET extract, other extracts of JG can inhibit cytochrome CYP2E1 expression to protect liver tissue. These findings suggest that the extracts and its components of JG possesses the potential protective effects against CCl₄-induced liver injury in mice by exerting antioxidative stress and anti-inflammation.

Hordenine Protects Against Lipopolysaccharide-Induced Acute Lung Injury by Inhibiting Inflammation

Acute lung injury (ALI) is a respiratory disease that leads to death in severe cases. Hordenine (Hor), a barley-derived natural product, has various biological activities, including anti-inflammatory, and anti-oxidation activities. We investigated the effect of Hor on lipopolysaccharide-induced ALI and its potential mechanism. The anti-inflammatory effects of Hor were detected using in vivo and in vitro models by enzyme-linked immunosorbent assay, real-time polymerase chain reaction, western blotting, and molecular docking simulations. Hor inhibited increases in the levels of inflammatory factors both in vivo and in vitro, and its anti-inflammatory effect inhibited activation of protein kinase B, nuclear factor-κB, and mitogen-activated protein kinase signaling. Hor alleviated lipopolysaccharide-induced ALI by inhibiting inflammatory cytokine increases in vivo and in vitro and shows potential for preventing inflammatory disease.

Evaluation of cyclooxygenase-2 fluctuation via a near-infrared fluorescent probe in idiopathic pulmonary fibrosis cell and mice models

Idiopathic pulmonary fibrosis (IPF) is a devastating and fatal interstitial lung disease due to various challenges in diagnosis and treatment. Due to its complicated pathogenesis and difficulty in early diagnosis, there is no effective cure. Cyclooxygenase-2 (COX-2) is inextricably associated with pulmonary fibrosis. The abnormal level of COX-2 leads to extremely exacerbated pulmonary fibrosis. Therefore, we reported a near-infrared fluorescent probe Cy-COX to detect the fluctuation of COX-2 levels during pulmonary fibrosis and explain its important protective effect. The probe Cy-COX showed a significant enhancement of fluorescence signal to COX-2 with excellent selectivity and sensitivity. In order to clarify the relationship between COX-2 and pulmonary fibrosis, we used the probe Cy-COX to detect COX-2 fluctuation in organisms with pulmonary fibrosis. The results showed that the COX-2 level increased in the early stage and decreased in the late stage with the aggravation of pulmonary fibrosis. Furthermore, up-regulation of COX-2 levels can effectively alleviate the severity of pulmonary fibrosis. Therefore, Cy-COX is a fast and convenient imaging tool with great potential to predict the early stage of pulmonary fibrosis and evaluate the therapeutic effects.

Hepatoprotective effects of Psidium guajava on mitochondrial enzymes and inflammatory markers in carbon tetrachloride-induced hepatotoxicity

OBJECTIVE

The present investigation was aimed to evaluate the hepatoprotective potential of ethanolic extract of Psidium guajava (P. guajva) and its isolated quercetin fraction on carbon tetrachloride (CCl₄)-induced hepatotoxicity.

MATERIALS AND METHODS

The rats were divided into 6 groups and each group contained 6 rats. CCl₄ (1.5 ml/kg b.w.) was used to induce the hepatotoxicity. Ethanolic extract of P. guajava (300 mg/kg b.w.), isolated quercetin fraction (20 mg/kg b.w.) were used as a treatment and silymarin (25 mg/kg b.w.) was used as a standard drug. After the study period, the liver tissues were collected and evaluate the levels of liver functional markers, mitochondrial enzymes, histopathological analysis and the expressions of inflammatory markers.

RESULTS

The levels of liver functional markers were increased and protein, albumin and A/G ratio levels were decreased and the decreased levels of mitochondrial enzymes were noted in CCl₄-induced rats and the levels were restored near to normal significantly when the administration ethanolic extract of P. guajava, isolated quercetin fraction and silymarin. The normal architecture of liver tissues were altered and the mRNA expressions were up-regulated in CCl₄-induced rats and the liver tissues were normalized and the mRNA and protein expressions were down-regulated near to normal significantly when the administration of ethanolic extract of P. guajava, isolated quercetin fraction and silymarin.

CONCLUSION

From these results, the isolated quercetin fractions have better activity than that of the ethanolic extract of P. guajava leaves. Hence, the isolated quercetin may be used as the safest drug for hepatotoxicity in future.

In-depth hepatoprotective mechanistic study of Phyllanthus niruri: In vitro and in vivo studies and its chemical characterization

Phyllanthus niruri L. is a widespread tropical plant which is used in Ayurvedic system for liver and kidney ailments. The present study aims at specifying the most active hepatoprotective extract of P. niruri and applying a bio-guided protocol to identify the active compounds responsible for this effect. P. niruri aerial parts were extracted separately with water, 50%, 70% and 80% ethanol. The cytoprotective activity of the extracts was evaluated against CCl₄-induced hepatotoxicity in clone-9 and Hepg2 cells. Bioassay-guided fractionation of the aqueous extract (AE) was accomplished for the isolation of the active compounds. Antioxidant activity was assessed using DPPH (1, 1-diphenyl-2-picrylhydrazyl) radical scavenging method and ferric reducing antioxidant power (FRAP). The in vivo hepatoprotective activity of AE was evaluated in CCl₄-induced hepatotoxicity in rats at different doses after determination of its LD₅₀. Pretreatment of clone-9 and Hepg2 with different concentrations of AE (1, 0.1, 0.01 mg/ml) had significantly reduced the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) against CCl₄ injures, and restored the activity of the natural antioxidants; glutathione (GSH) and superoxide dismutase (SOD) towards normalization. Fractionation of AE gave four fractions (I-IV). Fractions I, II, and IV showed a significant in vitro hepatoprotective activity. Purification of I, II and IV yielded seven compounds; corilagin C1, isocorilagin C2, brevifolin C3, quercetin C4, kaempferol rhamnoside C5, gallic acid C6, and brevifolin carboxylic acid C7. Compounds C1, C2, C5, and C7 showed the highest (p< 0.001) hepatoprotective potency, while C3, C4, and C6 exhibited a moderate (p< 0.001) activity. The AE exhibited strong antioxidant DPPH (IC₅₀ 11.6 ± 2 μg/ml) and FRAP (79.352 ± 2.88 mM Ferrous equivalents) activity. In vivo administration of AE in rats (25, 50, 100 and 200 mg/kg) caused normalization of AST, ALT, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), total cholesterol (TC), triglycyrides (TG), total bilirubin (TB), glucose, total proteins (TP), urea and creatinine levels which were elevated by CCl₄. AE also decreased TNF-α, NF-KB, IL-6, IL-8, IL10 and COX-2 expression, and significantly antagonizes the effect of CCl₄ on the antioxidant enzymes SOD, catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GSP). The histopathological study also supported the hepatoprotective effect of AE. P. niruri isolates exhibited a potent hepatoprotective activity against CCl₄-induced hepatotoxicity in clone-9 and Hepg2 cell lines through reduction of lipid peroxidation and maintaining glutathione in its reduced form. This is attributable to their phenolic nature and hence antioxidative potential.

Protective effect of Moringa oleifera leaves ethanolic extract against thioacetamide-induced hepatotoxicity in rats via modulation of cellular antioxidant, apoptotic and inflammatory markers

The current study was conducted to evaluate the ameliorative and protective potentials of Moringea oleifera leaves ethanolic extract (MOLE) against thioacetamide (TAA) toxicity. A total of 58 male albino rats were randomly assigned into six experimental groups. G1, rats received distilled water. G2, rats were injected with a single dose of TAA (200 mg/kg BW) i.p. G3, rats were given MOLE (300 mg/kg BW) orally for 26 days. G4, rats were injected TAA as in G2 and treated with MOLE as G3. G5, rats were kept for 26 days without treatment then on day 27 injected with TAA as in G2. G6, rats were given MOLE for 26 days then on day 27 injected with TAA. Phytochemical analysis of MOLE indicated the presence of kaempferol, kaempferol malonylglucoside, kaempferol hexoside, kaempferol -3-O-glucoside, kaempferol-3-O-acetyl-glucoside, cyanidin -3-O-hexoside, ellagic acid, quercetin, quercetin-3-O-glucoside, and apigenin glucoside. Intoxication of rats with TAA significantly elevated activities of serum AST, ALT, and ALP; concentrations of malondialdehyde, nitric oxide, and hepatic tissue protein expression of caspase 3 and COX2 with alteration of the histological structures of hepatic tissues, while it decreased serum levels of total protein, albumin, and hepatic tissue contents of reduced glutathione. Also, TAA intoxication resulted in 62.5% mortality in rats of G5. Treatment of TAA intoxicated rats (G4) with MOLE ameliorated the toxic effects of TAA on hepatic tissue structure and function. It decreased serum activities of AST, ALT, and ALP; enhanced hepatic GSH concentration; reduced pathological alterations and lipid peroxidation; and downregulated caspase 3 and COX2 proteins expression in hepatic tissue. In addition, MOLE protected rats of G6 from TAA-induced hepatic tissues injury and dysfunction, and increased survival rate of rats. In conclusion, MOLE had both ameliorating and protecting potentials against TAA-induced rats liver damage through regulation of antioxidant, anti-apoptotic, and inflammatory biomarkers. Graphical abstract.

Prediagnostic levels of urinary 8-epi-prostaglandin F2α and prostaglandin E2 metabolite, biomarkers of oxidative damage and inflammation, and risk of hepatocellular carcinoma

Chronic inflammation and oxidative stress play pivotal roles in the pathogenesis of hepatocellular carcinoma (HCC). We conducted a nested case-control study of 347 HCC cases and 691 matched controls within a prospective cohort of 18 244 Chinese men in Shanghai, China. The concentrations of 8-epi-prostaglandin F2α (8-epi-PGF2α), a biomarker of oxidative stress, and prostaglandin E2 (PGE2) metabolite (PGE-M), a biomarker of the inflammation mediator PGE2, were determined in baseline urine samples using validated mass spectrometry assays. 8-epi-PGF2α levels were significantly higher in HCC cases than control subjects (geometric means 0.92 versus 0.80 pmol/mg creatinine, P < 0.001). The relative risks of developing HCC for the highest relative to the lowest quartile of 8-epi-PGF2α were 2.55 (95% confidence interval = 1.62-4.01, Ptrend < 0.001). This positive 8-epi-PGF2α-HCC risk association was independent of smoking status, alcohol consumption and hepatitis B or liver cirrhosis and was present 10 years before the clinical manifestation of HCC. This study did not find any significant association between urinary PEG-M and HCC risk. This study provides direct evidence in support of the critical role of oxidative stress in the development of HCC regardless of its underlying causes.

Evaluation of Hepatoprotective Effect of Curcumin on Liver Cirrhosis Using a Combination of Biochemical Analysis and Magnetic Resonance-Based Electrical Conductivity Imaging

In oriental medicine, curcumin is used to treat inflammatory diseases, and its anti-inflammatory effect has been reported in recent research. In this feasibility study, the hepatoprotective effect of curcumin was investigated using a rat liver cirrhosis model, which was induced with dimethylnitrosamine (DMN). Together with biochemical analysis, we used a magnetic resonance-based electrical conductivity imaging method to evaluate tissue conditions associated with a protective effect. The effects of curcumin treatment and lactulose treatment on liver cirrhosis were compared. Electrical conductivity images indicated that liver tissues damaged by DMN showed decreased conductivity compared with normal liver tissues. In contrast, cirrhotic liver tissues treated with curcumin or lactulose showed increased conductivity than tissues in the DMN-only group. Specifically, conductivity of cirrhotic liver after curcumin treatment was similar to that of normal liver tissues. Histological staining and immunohistochemical examination showed significant levels of attenuated fibrosis and decreased inflammatory response after both curcumin and lactulose treatments compared with damaged liver tissues by DMN. The conductivity imaging and biochemical examination results indicate that curcumin's anti-inflammatory effect can prevent the progression of irreversible liver dysfunction.

Risk factors and prevention of hepatocellular carcinoma in the era of precision medicine

Patients who develop chronic fibrotic liver disease, caused by viral or metabolic aetiologies, are at a high risk of developing hepatocellular carcinoma (HCC). Even after complete HCC tumour resection or ablation, the carcinogenic tissue microenvironment in the remnant liver can give rise to recurrent de novo HCC tumours, which progress into incurable, advanced-stage disease in most patients. Thus, early detection and prevention of HCC development is, in principle, the most impactful strategy to improve patient prognosis. However, a "one-size-fits-all" approach to HCC screening for early tumour detection, as recommended by clinical practice guidelines, is utilised in less than 20% of the target population, and the performance of screening modalities, including ultrasound and alpha-fetoprotein, is suboptimal. Furthermore, optimal screening strategies for emerging at-risk patient populations, such as those with chronic hepatitis C after viral cure, or those with non-cirrhotic, non-alcoholic fatty liver disease remain controversial. New HCC biomarkers and imaging modalities may improve the sensitivity and specificity of HCC detection. Clinical and molecular HCC risk scores will enable precise HCC risk prediction followed by tailoured HCC screening of individual patients, maximising cost-effectiveness and optimising allocation of limited medical resources. Several aetiology-specific and generic HCC chemoprevention strategies are evolving. Epidemiological and experimental studies have identified candidate chemoprevention targets and therapies, including statins, anti-diabetic drugs, and selective molecular targeted agents, although their clinical testing has been limited by the lengthy process of cancer development that requires long-term, costly studies. Individual HCC risk prediction is expected to overcome the challenge by enabling personalised chemoprevention, targeting high-risk patients for precision HCC prevention and substantially improving the dismal prognosis of HCC.

Herbal remedies for liver fibrosis: A review on the mode of action of fifty herbs

Liver fibrosis is a dynamic pathological condition which can be slowed down in its initial phases. Without proper clinical management of fibrosis, progressive liver damage may lead to cirrhosis and ultimately to liver failure or primary liver cancer, which are irreversible conditions. Therefore, in order to cure fibrotic damage to liver, its early stages should be the centre of attention. In this context, some supplements and ‘complementary and alternative medicine (CAM)’ deserve specific mention, because of their already recognized natural way of healing and long lasting curative effects. Moreover, CAM display negligible side effects and hence it is gaining worldwide importance in clinical practices. In particular, herbal medicines are now replacing synthetic pharmaceuticals and looked upon as the sources of novel bioactive substances. To develop satisfactory herbal combinations for treating liver fibrosis, phytoproducts need to be systematically evaluated for their potency as anti-fibrotic, anti-hepatotoxic and antioxidant agents. More importantly, the identified herb/agent should have the remarkable tendency to stimulate hepatocytes regeneration. The present review is a systematic account of at least fifty medicinal herbs and their products which in experimental models have demonstrated antifibrotic activity and thus, most likely candidates to offer therapeutic protection to liver. Nevertheless, much additional work is still needed to explore molecular pathways to discover potential applications of these medicines so as to open up new vistas in biomedical research.

Antifibrotic effects of crocin on thioacetamide-induced liver fibrosis in mice

Liver fibrosis is a major health concern that results in significant morbidity and mortality. Up-to-date, there is no standard treatment for fibrosis because of its complex pathogenesis. Crocin is one of the main nutraceuticals isolated from the stigma of Crocus sativus with antioxidant and anti-inflammatory activities. The current study aimed at evaluating the potential antifibrotic activity of crocin against thioacetamide (TAA)-induced liver fibrosis in mice as well as the underlying mechanism using silymarin as a reference antifibrotic product. Crocin at two doses (25 and 100 mg/kg) significantly ameliorated the rise in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, and total bilirubin (TB). Further, the high dose significantly protected against the increase in serum total cholesterol (TC) and triglycerides (TG). These effects were confirmed by light microscopic examinations. Crocin antioxidant activities were confirmed by the observed inhibition of reduced glutathione depletion (GSH), super oxide dismutase (SOD) exhaustion and malondialdehyde (MDA) accumulation in liver tissue. The antifibrotic effects of crocin were explored by assessing fibrosis related gene expression. Administration of crocin (100 mg/kg) hampered expression of tumor growth factor-β (TGF-β), α alpha smooth muscle actin (α-SMA) and collagen 1-α expression and significantly raised gene expression of matrix metalloproteinase-2 (MMP-2). Further, it reduced protein expression of nuclear factor-κB (NF-κB) and cyclooxygenase-2 (COX-2) as assessed immunohistochemically. These anti-inflammatory effects were confirmed by the observed protein expression of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Thus, it can be concluded that crocin protects against TAA-induced liver fibrosis in mice. This can be ascribed, at least partly, to its antioxidant and anti-inflammatory effects.

Protective effect of Pyropia yezoensis glycoprotein on chronic ethanol consumption-induced hepatotoxicity in rats

The present study investigated the protective effect of Pyropia yezoensis glycoprotein (PYGP) against chronic ethanol consumption‑mediated hepatotoxicity in rats. Male Sprague-Dawley rats (n=20; 6 weeks old) were randomly divided into four groups. The rats in each group were treated for 30 days with the following: i) CON group, distilled water only; ii) EtOH group, 20% ethanol 3.7 g/kg/BW; iii) EtOH+150 group, 20% ethanol 3.7 g/kg/BW+PYGP 150 mg/kg/BW; iv) EtOH+300 group, 20% ethanol 3.7 g/kg/BW+PYGP 300 mg/kg/BW. EtOH, PYGP and water were orally administered. The rats were sacrificed after 30 days, and blood and liver samples were collected for analysis. Treatment with ethanol caused significant elevation of serum levels of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT). Furthermore, inhibition of the antioxidant defense system in the liver, including glutathione (GSH), glutathione peroxidase (GSH‑px) and catalase (CAT) was observed. However, co‑administration with PYGP recovered the antioxidant defense system, and the serum levels of GOT and GPT. PYGP was shown to attenuate ethanol toxicity via the inactivation of mitogen‑activated protein kinases (MAKPs). PYGP suppressed the overexpression of cytochrome P450 2E1 (CYP2E1), inducible nitric oxide synthase and cyclooxygenase‑2. These results suggested that the protective effect of PYGP was associated with antioxidant activities, MAPKs and the CYP2E1 signaling pathway.

Mitigation of 5-fluorouracil-induced liver damage in rats by vitamin C via targeting redox-sensitive transcription factors

Adverse complications associated with antineoplastic drug-based cancer therapy are the major clinical drawbacks. Oxidative stress and inflammation play a major role in the damage due to cancer therapy. In the current study, we investigated the modulatory effect of vitamin C (Vit. C) on liver toxicity induced by 5-fluorouracil (5-FU) in rats. Animals were divided into four groups. Animals in group I received vehicle. Oral gavage of Vit. C (500 mg kg^-1 body weight (b.wt.)) was given to the animals in group III and group IV. 5-FU (150 mg kg^-1 b.wt.) was injected intraperitoneally to the animals in group II and group III. Findings of the present study revealed that oral administration of Vit. C significantly ameliorated the level of lipid peroxidation and the activity of myeloperoxidase. Vit. C administration markedly reduced the activation of nuclear factor κB and expression of cyclooxygenase 2, whereas nuclear translocation of nuclear factor erythroid 2-related factor 2 was increased. Hepatic histopathological analyses further supported the protective effect of Vit. C. Findings of the current study demonstrate that the toxic free radicals and inflammatory mediators generated due to chemotherapy play a critical role in 5-FU-induced hepatic damage. Attenuating action of Vit. C may be due to the modulation of redox-sensitive transcription factors and associated target molecules.

Cynanchum wilfordii Radix attenuates liver fat accumulation and damage by suppressing hepatic cyclooxygenase-2 and mitogen-activated protein kinase in mice fed with a high-fat and high-fructose diet

Excessive consumption of fat and fructose augments the pathological progression of nonalcoholic fatty liver disease through hepatic fibrosis, inflammation, and hepatic de novo lipogenesis. We hypothesized that supplementation with Cynanchum wilfordii extract (CWE) decreases fat accumulation in the liver by suppressing cyclooxygenase-2 (COX-2), the nuclear translocation of nuclear factor κB (NF-κB), and p38 mitogen-activated protein kinase (MAPK). The beneficial effect of CWE was evaluated in a murine model of nonalcoholic fatty liver disease. Mice were fed either a normal diet or an atherogenic diet with fructose (ATHFR) in the presence or absence of CWE (50, 100, or 200 mg/kg; n=6/group). Treatment with ATHFR induced a hepatosplenomegaly-like condition (increased liver and spleen weight); this pathological change was attenuated in the presence of CWE. The ATHFR group exhibited impaired liver function, as evidenced by increased blood levels of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase, fat accumulation in the liver, and lipid profiles. Supplementation of CWE (100 and 200 mg/kg, P<.05) ameliorated these impaired liver functions. Atherogenic diet with fructose increased the protein levels of COX-2 and p38 MAPK, as well as the nuclear translocation of NF-κB. These signaling pathways, which are associated with the inflammatory response, were markedly suppressed after CWE treatment (100 and 200 mg/kg). In summary, CWE supplementation reduced high-fat and high-fructose diet-induced fat accumulation and damage in the liver by suppressing COX-2, NF-κB, and p38 MAPK.

Understanding the molecular aspects of oriental obesity pattern differentiation using DNA microarray

Background

Human constitution, the fundamental basis of oriental medicine, is categorized into different patterns for a particular disease according to the physical, physiological, and clinical characteristics of the individuals. Obesity, a condition of metabolic disorder, is classified according to six patterns in oriental medicine, as follows: spleen deficiency syndrome, phlegm fluid syndrome, yang deficiency syndrome (YDS), food accumulation syndrome (FAS), liver depression syndrome (LDS), and blood stasis syndrome. In oriental medicine, identification of the disease pattern for individual obese patients is performed on the basis of differentiation in obesity syndrome index and, accordingly, personalized treatment is provided to the patients. The aim of the current study was to understand the obesity patterns in oriental medicine from the genomic point of view via determining the gene expression signature of obese patients using peripheral blood mononuclear cells as the samples.

Methods

The study was conducted in 23 South Korean obese subjects (19 female and four male) with BMI ≥25 kg/m². Identification of oriental obesity pattern was based on the software-guided evaluation of the responses of the subjects to a questionnaire developed by the Korean Institute of Oriental Medicine. The expression profiles of genes were determined using DNA microarray and the level of transcription of genes of interest was further evaluated using quantitative real-time PCR (qRT-PCR).

Results and conclusion

Gene clustering analysis of the microarray data from the FAS, LDS, and YDS subjects exhibited disease pattern-specific upregulation of expression of several genes in a particular cluster. Further analysis of transcription of selected genes using qRT-PCR led to identification of specific genes, including prostaglandin endoperoxide synthase 2, G0/G1 switch 2, carcinoembryonic antigen-related cell adhesion molecule 3, cystein-serine-rich nuclear protein 1, and interleukin 8 receptor, alpha which were highly expressed in LDS obesity constitution. Our current study can be considered as a valuable contribution to the understanding of possible explanation for obesity pattern differentiation in oriental medicine. Further studies can address a novel possibility that the genomic and oriental empirical approaches can be combined and implemented in systematic and synergistic development of personalized medicine.

This clinical trial was registered in Clinical Research Information Service of Korea National Institute of Health (https://cris.nih.go.kr/cris/index.jsp). Registration number: KCT0000387

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0692-9) contains supplementary material, which is available to authorized users.

Effects of the total saponins from Rosa laevigata Michx fruit against acetaminophen-induced liver damage in mice via induction of autophagy and suppression of inflammation and apoptosis

The effect of the total saponins from Rosalaevigata Michx fruit (RLTS) against acetaminophen (APAP)-induced liver damage in mice was evaluated in the present paper. The results showed that RLTS markedly improved the levels of liver SOD, CAT, GSH, GSH-Px, MDA, NO and iNOS, and the activities of serum ALT and AST caused by APAP. Further research confirmed that RLTS prevented fragmentation of DNA and mitochondrial ultrastructural alterations based on TdT-mediated dUTP nick end labeling (TUNEL) and transmission electron microscopy (TEM) assays. In addition, RLTS decreased the gene or protein expressions of cytochrome P450 (CYP2E1), pro-inflammatory mediators (IL-1β, IL-4, IL-6, TNF-α, iNOS, Bax, HMGB-1 and COX-2), pro-inflammatory transcription factors (NF-κB and AP-1), pro-apoptotic proteins (cytochrome C, p53, caspase-3, caspase-9, p-JNK, p-p38 and p-ERK), and increased the protein expressions of Bcl-2 and Bcl-xL. Moreover, the gene expression of IL-10, and the proteins including LC3, Beclin-1 and Atg5 induced by APAP were even more augmented by the extract. These results demonstrate that RLTS has hepatoprotective effects through antioxidative action, induction of autophagy, and suppression of inflammation and apoptosis, and could be developed as a potential candidate to treat APAP-induced liver damage in the future.

Correlation of microRNA-16, microRNA-21 and microRNA-101 expression with cyclooxygenase-2 expression and angiogenic factors in cirrhotic and noncirrhotic human hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a classical example of inflammation-linked cancer and is characterized by hypervascularity suggesting rich angiogenesis. Cycloxygenase-2 (COX-2) is a potent mediator of inflammation and is considered to upregulate angiogenesis. The aims of the study are (1) to analyze expression of Cox-2 mRNA, Cox-2 protein, miR-16, miR-21 and miR-101 in HCC and adjacent liver parenchyma in cirrhotic and noncirrhotic liver, (2) to investigate the relation between COX-2 expression, miR-21 expression and angiogenic factors in these tissues and (3) to investigate the association between miR-16 and miR-101 and COX-2 expression.

METHODS

Tissue samples of HCC and adjacent liver parenchyma of 21 noncirrhotic livers and 20 cirrhotic livers were analyzed for COX-2 expression at the mRNA level (qRT-PCR) and at the protein level by Western blot and immunohistochemistry. Gene expression of VEGFA, VEGFR1, VEGFR2, Ang-1, Ang-2 and Tie-2 were correlated with COX-2 levels. miR-16, miR-21 and miR-101 gene expression levels were quantified in HCC tumor tissue.

RESULTS

COX-2 mRNA and protein levels were lower in HCC as compared to adjacent liver parenchyma both in cirrhotic and noncirrhotic liver. COX-2 protein localized mainly in vascular and sinusoidal endothelial cells and in Kupffer cells. At the mRNA level but not at the protein level, COX-2 correlated with mRNA levels of angiogenic factors VEGFR1, Ang-1, and Tie2. miR-21 expression was higher in cirrhotic tissues versus noncirrhotic tissues. MiR-101 expression was lower in cirrhotic versus noncirrhotic adjacent liver parenchyma. None of the miRNAs correlelated with COX-2 expression. miR-21 correlated negatively with Tie-2 receptor in adjacent liver parenchyma.

CONCLUSIONS

In human HCC, COX-2 mRNA but not COX-2 protein levels are associated with expression levels of angiogenic factors. MiR-21 levels are not associated with angiogenic molecules. MiR-16 and miR-101 levels do not correlate with COX-2 mRNA and protein levels.

Prostaglandin E2 promotes hepatocellular carcinoma cell invasion through upregulation of YB-1 protein expression

Prostaglandin E2 (PGE2) has been implicated in hepatocellular carcinoma cell invasion. Recently, it was reported that Y box-binding protein 1 (YB-1) is closely correlated with malignancy. This study was designed to examine the mechanisms by which PGE2 increases YB-1 expression and promotes HCC cell invasion. PGE2 greatly enhanced HCC cell invasion through upregulation of the YB-1 protein, and the EP1 receptor is mainly responsible for this regulation. Src and EGFR were both activated by PGE2, which in turn increased the phosphorylation levels of p44/42 MAPK. Src, EGFR and p44/42 MAPK were all involved in PGE2-induced YB-1 expression. Chemical inhibitors and RNAi analysis all confirmed the role of mTOR complex 1 in YB-1 expression induced by PGE2. Furthermore, YB-1 was able to regulate the expression of a series of EMT-associated genes, which indicated that YB-1 could have the potential to control the epithelial-mesenchymal transition process in HCC cells. These findings reveal that PGE2 upregulated YB-1 expression through the EP1/Src/EGFR/p44/42 MAPK/mTOR pathway, which greatly enhanced HCC cell invasion. This study for the first time describes the mechanisms through which PGE2 regulates YB-1 expression and promotes HCC cell invasion.

Multimechanistic antifibrotic effect of biochanin a in rats: implications of proinflammatory and profibrogenic mediators

OBJECTIVE

Biochanin A (BCA) is an isoflavone found in red clover and peanuts. Recently, it drew much attention as a promising anticancer and antioxidant. Due to its diversity in pharmacological actions, we were encouraged to investigate its potential as an antifibrotic, elucidating the different molecular mechanisms involved.

DESIGN

Rats were pretreated with BCA, then injected with carbon tetrachloride (CCl4) for 6 weeks. Changes in liver weight and histology were examined and levels of aspartate and alanine aminotransferases, cholesterol, triglycerides, alkaline phosphatase and total bilirubin measured. To assess hepatic efficiency, indocyanine green was injected and its clearance calculated and albumin, total proteins and insulin-like growth factor-1 expression were measured. Cytochrome P4502E1 activity, cytochrome P4501A1 expression, in addition to sulfotransferase1A1 expression were determined to deduce the effect of BCA on hepatic metabolism. As oxidative stress markers, lipid peroxides levels, reduced glutathione, superoxide dismutase and catalase activities, as well as the total antioxidant capacity, were assessed. Nitric oxide, inducible nitric oxide synthase and cyclooxygenase-2 were used as indicators of the inflammatory response. Signaling pathways involving tumor necrosis factor-alpha, nuclear factor-kappa B, transforming growth factor-beta1, matrix metalloproteinase-9 and alpha-smooth muscle actin were investigated accordingly. Extent of fibrosis was examined by Masson's stain and measuring hydroxyproline levels.

RESULTS

BCA pretreatment significantly protected against the chronic damage of CCl4. Liver injury, oxidative stress, inflammation and fibrosis markers decreased, while hepatic efficiency improved.

CONCLUSION

Our findings suggested that BCA administration protects against fibrotic complications, a property that can be contributed to the multimechanistic approach of the drug.

Activated hepatic stellate cells mediate the differentiation of macrophages

AIM

Liver macrophages play integral roles in both the progression and resolution of hepatic inflammation and fibrosis, comprising opposing functions that largely coincide with the activation state of nearby hepatic stellate cells (HSC). While cross-talk between HSC and macrophages may be essential at various stages of inflammation and fibrogenesis, many facets of this interaction have yet to be thoroughly explored. Here, we examine the potential roles of HSC-derived signaling molecules as mediators of liver macrophage differentiation.

METHODS

Human peripheral blood mononuclear cells (PBMC) were differentiated to macrophages in the presence or absence of cultured HSC-derived conditioned media. The phenotype of resulting macrophages was characterized by examination of cell surface marker expression, antigen-presenting capabilities and cytokine secretion.

RESULTS

Conditioned media from activated human HSC promoted the differentiation of a unique set of macrophages that differed in morphology and function from both classical (M1) and alternative (M2) macrophages, expressing increased levels of CD14 and CD16, as well as a distinct interleukin (IL)-6(high) /IL-10(low) /transforming growth factor (TGF)-β(high) expression profile. These macrophages expressed high levels of CD206, CD209, CD80 and human leukocyte antigen DR, though no significant increases in antigen presentation were apparent. HSC-derived macrophages exhibited specific activation of p38 mitogen-activated protein kinase, and inhibition of this activation by p38 inhibitors during differentiation effectively reversed increases in IL-6 and TGF-β.

CONCLUSION

The present results suggest that HSC-derived signaling molecules promote differentiation of liver macrophages with both pro-inflammatory and profibrotic functions. Furthermore, these effects appear to be mediated, at least partially, in a p38-dependent manner.

Ameliorative effect of grape seed proanthocyanidin extract on thioacetamide-induced mouse hepatic fibrosis

The present study was designed to examine the effect of the grape seed proanthocyanidin extract (GSPE) on developing hepatic fibrosis that was induced by thioacetamide (TAA) in mice. Administration of TAA for 9 weeks led to a serious necrosis and apoptosis of the parenchymal cells, which resulted in an accumulation of excessive collagen in the liver and an increase of transformed hepatic stellate cells (HSCs). In addition, the mRNA expression of transforming growth factor β1 (TGF-β1), α-smooth muscle actin (α-SMA), as the marker of the activated HSCs, and α1-(I)-collagen were all up-regulated significantly when compared with the control. However, combined oral administration of GSPE at 100 mg/kg suppressed the mRNA expression of TGF-β1 and α-SMA, with decreased collagen accumulation as demonstrated by histomorphological evaluation and quantitative RT-PCR. The mRNA expression of the pro-inflammatory factors, including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), was remarkably enhanced by TAA treatment. However, their levels displayed a down-regulated trend beyond simultaneous GSPE treatment. Moreover, GSPE administration markedly suppressed lipid peroxidation. In conclusion, as a plant antioxidant, GSPE manifested effective hepatocellular protective action to ameliorate the developing liver fibrosis induced by chronic TAA administration in mice.

Celecoxib, a selective cyclooxygenase-2 inhibitor, lowers plasma cholesterol and attenuates hepatic lipid peroxidation during carbon-tetrachloride-associated hepatotoxicity in rats

Cyclooxygenase-2 (COX-2) expression and prostaglandin production are suggested to play important, complex roles in the pathogenesis of various liver diseases. Studies on the effects of COX-2 inhibitors on the progression of liver fibrosis present controversial results, and the proposed therapeutic potential of these agents in chronic liver disease is predicated largely on their effectiveness in modulating hepatic stellate cell activation in vitro. This study investigated the modulatory effect of celecoxib, a selective COX-2 inhibitor, in CCl(4)-mediated hepatotoxicity in rats. Thirty Wistar albino rats, weighing 120-180 g, were assigned into five groups of 6 rats/group. Groups 1 and 2 received saline (10 mL/kg) and CCl(4) (80 mg/kg), respectively. Group 3 was given celecoxib (5.7 mg/kg), whereas groups 4 and 5 were pretreated with 2.9 and 5.7 mg/kg/day of celecoxib, respectively, 1 hour before CCl(4) treatment. Plasma aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activities increased significantly by 118.5, 150.0, and 51.3%, respectively, with an accompanying decrease (P < 0.05) in total protein and albumin after CCl(4) treatment. Hepatotoxicity was associated with a significant increase in plasma cholesterol, hepatic lipid peroxidation (LPO), and severe hepatic necrosis with marked fatty and cellular (i.e., mononuclear cells) infiltration. Although celecoxib neither reduced CCl(4)-induced increases in marker enzymes of hepatotoxicity nor significantly attenuated hepatic necrosis, it, however, was effective in reducing elevated cholesterol by 16.5 and 20.8% and LPO by 12.9 and 35.5% at 2.9 and 5.7 mg/kg, respectively. Data suggest that COX-2 inhibitors may be effective in controlling hypercholesterolemia and peroxidative changes associated with liver injury.

Immunodetection of cyclooxygenase-2 (COX-2) is restricted to tissue macrophages in normal rat liver and to recruited mononuclear phagocytes in liver injury and cholangiocarcinoma

It has been suggested that cyclooxygenase-2 (COX-2)-mediated prostaglandin synthesis is associated with liver inflammation and carcinogenesis. The aim of this study is to identify the cellular source of COX-2 expression in different stages, from acute liver injury through liver fibrosis to cholangiocarcinoma (CC). We induced in rats acute and "chronic" liver injury (thioacetamide (TAA) or carbon tetrachloride (CCl(4))) and CC development (TAA) and assessed COX-2 gene expression in normal and damaged liver tissue by RT-PCR of total RNA. The cellular localization of COX-2 protein in liver tissue was analyzed by immunohistochemistry as well as in isolated rat liver cells by Western blotting. The findings were compared with those obtained in human cirrhotic liver tissue. The specificity of the antibodies was tested by 2-DE Western blot and mass spectrometric identification of the positive protein spots. RT-PCR analysis of total RNA revealed an increase of hepatic COX-2 gene expression in acutely as well as "chronically" damaged liver. COX-2-protein was detected in those ED1(+)/ED2(+) cells located in the non-damaged tissue (resident tissue macrophages). In addition COX-2 positivity in inflammatory mononuclear phagocytes (ED1(+)/ED2(-)), which were also present within the tumoral tissue was detected. COX-2 protein was clearly detectable in isolated Kupffer cells as well as (at lower level) in isolated "inflammatory" macrophages. Similar results were obtained in human cirrhotic liver. COX-2 protein is constitutively detectable in liver tissue macrophages. Inflammatory mononuclear phagocytes contribute to the increase of COX-2 gene expression in acute and chronic liver damage induced by different toxins and in the CC microenvironment.

Insights antifibrotic mechanism of methyl palmitate: impact on nuclear factor kappa B and proinflammatory cytokines

Fibrosis accompanies most chronic liver disorders and is a major factor contributing to hepatic failure. Therefore, the need for an effective treatment is evident. The present study was designed to assess the potential antifibrotic effect of MP and whether MP can attenuate the severity of oxidative stress and inflammatory response in chronic liver injury. Male albino rats were treated with either CCl(4) (1 ml/kg, twice a week) and/or MP (300 mg/kg, three times a week) for six weeks. CCl(4)-intoxication significantly increased liver weight, serum aminotransferases, total cholesterol and triglycerides while decreased albumin level and these effects were prevented by co-treatment with MP. As indicators of oxidative stress, CCl(4)-intoxication caused significant glutathione depletion and lipid peroxidation while MP co-treatment preserved them within normal values. As markers of fibrosis, hydroxyproline content and α-SMA expression increased markedly in the CCl(4) group and MP prevented these alterations. Histopathological examination by both light and electron microscope further confirmed the protective efficacy of MP. To elucidate the antifibrotic mechanisms of MP, the expression of NF-κB, iNOS and COX-2 and the tissue levels of TNF-α and nitric oxide were assessed; CCl(4) increased the expression of NF-κB and all downstream inflammatory cascade while MP co-treatment inhibited them. Collectively these findings indicate that MP possesses a potent antifibrotic effect which may be partly a consequence of its antioxidant and anti-inflammatory properties.

A maternal high-fat diet represses the expression of antioxidant defense genes and induces the cellular senescence pathway in the liver of male offspring rats

Maternal high-fat (HF) diet feeding is associated with increased risk of developing metabolism-related diseases in adult offspring, including chronic liver disease. The present study tested the hypothesis that maternal HF diet leads to a decreased antioxidant defense capacity and causes cellular senescence in liver of adult offspring rats, which might increase risk of developing chronic liver disease. Timed-pregnant Sprague Dawley rats were fed a HF diet (45% of energy from fat) or a control (C) diet (16% of energy from fat) during gestation and lactation. The resulting offspring were fed a C diet after weaning to generate 2 offspring groups: C diet-fed offspring of dams fed C diet (C/C) and C diet-fed offspring of dams fed a HF diet (HF/C). At 12 wk of age, male rats were killed and samples were collected for analysis. Maternal HF diet significantly increased plasma TG and hepatic TBARS concentrations and the size of hepatic lipid droplets in offspring rats. The expression of antioxidant defense genes, such as glutathione peroxidase-1, Cu/Zn superoxide dismutase (Sod1), paraoxonase enzymes (Pon1, Pon2, and Pon3), were significantly lower in the liver of HF/C pups than in C/C pups. The expression of Inhibitor of cyclin dependent Kinase 4a (p16INK4a), a marker of cellular senescence, and cyclooxygenase-2 (Cox2), a proinflammatory marker, was significantly higher in the HF/C offspring group than in the C/C offspring group. Western-blot analysis shows that cyclin D1 and phosphorylated retinoblastoma protein were significantly lower in HF/C offspring than in C/C offspring. The results provide the first evidence to our knowledge that maternal HF diet might alter antioxidant defense capacity and program the p16INK4a-dependent cellular senescence in the liver of adult offspring.

Role of STK in mouse liver macrophage and endothelial cell responsiveness during acute endotoxemia

Acute endotoxemia is associated with excessive production of proinflammatory mediators by hepatic macrophages and endothelial cells, which have been implicated in liver injury and sepsis. In these studies, we analyzed the role of MSP and its receptor STK in regulating the activity of these cells. Acute endotoxemia, induced by administration of LPS (3 mg/kg) to mice, resulted in increased expression of STK mRNA and protein in liver macrophages and endothelial cells, an effect that was dependent on TLR-4. This was correlated with decreased MSP and increased pro-MSP in serum. In Kupffer cells, but not endothelial cells, MSP suppressed LPS-induced NOS-2 expression, with no effect on COX-2. LPS treatment of mice caused a rapid (within 3 h) increase in the proinflammatory proteins NOS-2, IL-1beta, and TNF-alpha, as well as TREM-1 and TREM-3 and the anti-inflammatory cytokine IL-10 in liver macrophages and endothelial cells. Whereas LPS-induced expression of proinflammatory proteins was unchanged in STK-/- mice, IL-10 expression was reduced significantly. Enzymes mediating eicosanoid biosynthesis including COX-2 and mPGES-1 also increased in macrophages and endothelial cells after LPS administration. In STK-/- mice treated with LPS, mPGES-1 expression increased, although COX-2 expression was reduced. LPS-induced up-regulation of SOD was also reduced in STK-/- mice in liver macrophages and endothelial cells. These data suggest that MSP/STK signaling plays a role in up-regulating macrophage and endothelial cell anti-inflammatory activity during hepatic inflammatory responses. This may be important in protecting the liver from tissue injury.

Beneficial effects of Chinese prescription Kangen-karyu on diabetes associated with hyperlipidemia, advanced glycation endproducts, and oxidative stress in streptozotocin-induced diabetic rats

AIM OF THE STUDY

In the present study, we investigated the effects of Kangen-karyu, a traditional Chinese prescription comprising six herbs, on diabetes.

MATERIALS AND METHODS

Kangen-karyu extract (50, 100, or 200mg/kg body weight) was administered to streptozotocin (STZ)-induced diabetic rats and serum and hepatic biochemical factors, and protein expressions associated with oxidative stress and advanced glycation endproduct (AGE) formation were measured.

RESULTS

The oral administration of Kangen-karyu significantly ameliorated hypertriglyceridemia induced by STZ injection, while serum levels of glucose and total cholesterol were mildly affected. Kangen-karyu also markedly reduced the levels of AGEs and malondialdehyde (MDA), a lipid peroxide product used as an indicator of oxidative stress in both serum and hepatic tissue. In addition, Kangen-karyu dose-dependently lowered the expression levels of N(epsilon)-(carboxymethyl) lysine, one of the major component of AGEs closely associated with the pathogenesis of diabetes and liver cirrhosis, and receptor for AGEs, as well as the expression levels of nuclear factor-kappaB, inducible nitric oxide synthase, and cyclooxygenase-2 (COX-2) associated with oxidative stress. Especially, MDA levels in both serum and hepatic tissue and COX-2 expression increased by STZ were recovered by Kangen-karyu (200mg/kg body weight) to normal levels.

CONCLUSIONS

Kangen-karyu showed favorable effects on hypertriglycemia, AGE formation, and oxidative stress in STZ-treated rats, suggesting beneficial effects on diabetes, diabetic hepatopathy, and liver diseases such as cirrhosis, as well as cardiovascular and cerebrovascular diseases.

Prostaglandin E2 induces contraction of liver myofibroblasts by activating EP3 and FP prostanoid receptors

BACKGROUND AND PURPOSE

Increased portal pressure in liver injury results from hypercontraction of perivascular non-parenchymal cells including liver myofibroblasts (MFs). Prostaglandin E2 (PGE2) is the major eicosanoid which is released around the venous system during liver injury, but little is known about their contractile effect on MFs.

EXPERIMENTAL APPROACH

Contraction of primary rat liver MFs was measured by a collagen gel contraction assay. Expression of E prostanoid (EP) receptor subtypes was assessed by reverse transcription-polymerase chain reaction. Fura-2 fluorescence was used to determine intracellular Ca2+ concentration ([Ca2+](i)). Phosphorylation of protein kinase C (PKC) was detected by Western blot analysis.

KEY RESULTS

Liver MFs expressed mRNAs for all four EP receptors. PGE2 induced contraction in a dose- and time-dependent manner, and slightly increased [Ca2+](i) only at high concentrations (10 micromol.L(-1)). An agonist selective for EP(3) receptors, ONO-AE-248, dose-dependently induced MF contraction but did not increase [Ca2+](i). Pretreatment with rottlerin (a specific novel PKC inhibitor) and Ro 31-8425 (a general PKC inhibitor) significantly reduced 1 micromol.L(-1) PGE(2)- or ONO-AE-248-induced contractions. Furthermore, 1 micromol.L(-1) PGE(2) stimulated phosphorylation of PKC isoforms PKCdelta and PKCepsilon. The F prostanoid (FP) receptor antagonist AL8810 abolished the [Ca(2+)](i) elevation and the rapid contraction induced by 10 micromol.L(-1) PGE2.

CONCLUSIONS AND IMPLICATIONS

Lower concentrations up to 1 micromol.L(-1) of PGE2 induce liver MF contraction via a [Ca2+](i)-independent PKC-mediated pathway through the EP(3) receptor, while higher concentrations have an additional pathway leading to Ca(2+)-dependent contraction through activating the FP receptor.

Non-dioxin-like polychlorinated biphenyls induce a release of arachidonic acid in liver epithelial cells: a partial role of cytosolic phospholipase A(2) and extracellular signal-regulated kinases 1/2 signalling

Non-dioxin-like polychlorinated biphenyls (NDL-PCBs) have been shown to act as tumor promoters in liver; however, the exact mechanisms of their action are still only partially understood. One of the interesting effects of NDL-PCBs is the acute inhibition of gap junctional intercellular communication (GJIC), an effect, which has been often found to be associated with tumor promotion. As previous studies have suggested that NDL-PCB-induced disruption of lipid signalling pathways might correspond with GJIC inhibition, we investigated effects of PCBs on the release of arachidonic acid (AA) in the rat liver epithelial WB-F344 cell line, a well-established model of liver progenitor cells. We found that both 2,2',4,4'-tetrachlorobiphenyl (PCB 47) and 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153), but not the dioxin-like, non-ortho-substituted, 3,3',4,4',5-pentachlorobiphenyl (PCB 126), induce a massive release of AA. The AA release, induced by PCB 153, was partially inhibited by extracellular signal-regulated kinases 1/2 (ERK1/2) signalling inhibitor, U0126, and by cytosolic phospholipase A(2) (cPLA(2)) inhibitor, AACOCF(3). Although PCB 153 induced both ERK1/2 and p38 activation, the specific p38 kinase inhibitor, SB203580, had no effect on AA release. Inhibitors of other phospholipases, including phosphatidylcholine-specific phospholipase C or phosphatidylinositol-specific phospholipase C, were also without effect. Taken together, our findings suggest that the AA release, induced by non-dioxin-like PCBs in liver progenitor cell line, is partially mediated by cytosolic PLA(2) and regulated by ERK1/2 kinases. Our results suggest that more attention should be paid to cell signalling pathways regulated by AA or eicosanoids after PCB exposure, which might be involved in their toxic effects.

Lipids changes in liver cancer

Liver is one of the most important organs in energy metabolism. Most plasma apolipoproteins and endogenous lipids and lipoproteins are synthesized in the liver. It depends on the integrity of liver cellular function, which ensures homeostasis of lipid and lipoprotein metabolism. When liver cancer occurs, these processes are impaired and the plasma lipid and lipoprotein patterns may be changed. Liver cancer is the fifth common malignant tumor worldwide, and is closely related to the infections of hepatitis B virus (HBV) and hepatitis C virus (HCV). HBV and HCV infections are quite common in China and other Southeast Asian countries. In addition, liver cancer is often followed by a procession of chronic hepatitis or cirrhosis, so that hepatic function is damaged obviously on these bases, which may significantly influence lipid and lipoprotein metabolism in vivo. In this review we summarize the clinical significance of lipid and lipoprotein metabolism under liver cancer.

Cyclooxygenase-2 inhibitor ameliorates ureteric damage in rats with obstructed uropathy

To investigate the effect of cyclooxygenase-2 (COX-2) inhibitor on the tissue damage and fibrosis in obstructed ureters, 80 rats were studied. Celecoxib, a COX-2 inhibitor, was administered to 40 rats at the dose of 10 mg/kg per day 1 day before unilateral ligation of ureters and every day thereafter. The others, receiving unilateral ligation of ureters only, served as controls. Eight rats from each group were sacrificed for examination on days 7, 14, 21, 28 and 42 after ligation, respectively. The expressions of COX-2, prostaglandin E(2) (PGE(2)), transforming growth factor-beta(1) (TGFbeta(1)), alpha-smooth muscle actin (alpha-SMA), proliferation cell nuclear antigen (PCNA) and the apoptotic cells in the ureteric smooth muscle were examined. Hydroureter and fibrosis of the muscle layer became progressively aggravated during the period of obstruction in the ligated ureters of both groups. The severity of the hydroureter and fibrosis of muscle layer in the ligated ureters of the treated group was significantly milder than those of the control group. Expressions of COX-2 and PGE(2) were found in the smooth muscle layer of ligated ureters in the control group from day 14 after ureteric ligation, reached a peak on day 21, and then declined. Treatment with Celecoxib completely abolished the expression of COX-2 and PGE(2). The Celecoxib administration also decreased the expression of TGFbeta(1), alpha-SMA and the labeling index of apoptotic cells in the smooth muscle layer of ligated ureters in the treated group. In the contrast, treatment with Celecoxib significantly increased the expression of PCNA in the smooth muscle layer of ligated ureters in the treated group. We concluded that COX-2 inhibitor might ameliorate the damage of obstructed ureters, at least partly, via the inhibition of COX-2 and TGFbeta(1) expression.

Effect of prostaglandin E2 and prostaglandin I2 on PDGF-induced proliferation of LI90, a human hepatic stellate cell line

Hepatic stellate cells (HSC) are central to liver fibrosis. The eicosanoid pathway and cyclooxygenase-2 (COX-2) may be an important signaling mechanism in HSC. We investigated the role of COX-2, prostaglandin E(2) (PGE(2)) and prostaglandin I(2) (PGI(2)) in proliferation of LI90, an immortalized cell line of HSC. Our results showed that COX-2 was upregulated by platelet-derived growth factor (PDGF), a mitogen in HSC. COX-2 was responsible for the production of PGE(2) and PGI(2) in PDGF-stimulated LI90 cells. Furthermore, we demonstrated that COX-2 and PGE(2) mediated the proliferative response of LI90 to PDGF while synthetic analogue of PGI(2) exhibited anti-proliferative effect. Our findings suggest complex interactions of prostaglandins in liver fibrogenesis. In vivo studies using animal models are needed to elucidate the effect of COX-2 inhibition by non-steroidal anti-inflammatory drugs or COX-2 inhibitor in hepatic fibrosis.