Role of oxidative stress in alcohol-induced liver injury

Hepatic Transcriptome Responses in Mice (Mus musculus) Exposed to the Nafion Membrane and Its Combustion Products

Nafion 117 membrane (N117), an important polymer electrolyte membrane (PEM), has been widely used for numerous chemical technologies. Despite its increasing production and use, the toxicity data for N117 and its combustion products remain lacking. Toxicity studies are necessary to avoid problems related to waste disposal in landfills and incineration that may arise. In this study, we investigated the histopathological alterations, oxidative stress biomarker responses, and transcriptome profiles in the liver of male mice exposed to N117 and its combustion products for 24 days. An ion-chromatography system and liquid chromatography system coupled to a hybrid quadrupole time-of-flight mass spectrometry were used to analyze the chemical compositions of these combustion products. The transcriptomics analysis identified several significantly altered molecular pathways, including the metabolism of xenobiotics, carbohydrates and lipids; signal transduction; cellular processes; immune system; and signaling molecules and interaction. These studies provide preliminary data for the potential toxicity of N117 and its combustion products on living organisms and may fill the information gaps in the toxicity databases for the currently used PEMs.

Advances and New Concepts in Alcohol-Induced Organelle Stress, Unfolded Protein Responses and Organ Damage

Alcohol is a simple and consumable biomolecule yet its excessive consumption disturbs numerous biological pathways damaging nearly all organs of the human body. One of the essential biological processes affected by the harmful effects of alcohol is proteostasis, which regulates the balance between biogenesis and turnover of proteins within and outside the cell. A significant amount of published evidence indicates that alcohol and its metabolites directly or indirectly interfere with protein homeostasis in the endoplasmic reticulum (ER) causing an accumulation of unfolded or misfolded proteins, which triggers the unfolded protein response (UPR) leading to either restoration of homeostasis or cell death, inflammation and other pathologies under severe and chronic alcohol conditions. The UPR senses the abnormal protein accumulation and activates transcription factors that regulate nuclear transcription of genes related to ER function. Similarly, this kind of protein stress response can occur in other cellular organelles, which is an evolving field of interest. Here, I review recent advances in the alcohol-induced ER stress response as well as discuss new concepts on alcohol-induced mitochondrial, Golgi and lysosomal stress responses and injuries.

Absence of cytochrome P450 2A5 enhances alcohol-induced liver injury in mice

BACKGROUND

Ethanol can induce cytochrome P450 2E1, an active generator of reactive oxygen species, and this cytochrome is considered a risk factor for oxidative liver injury. Recently, we found that in addition to P450 2E1 also cytochrome P450 2A5, another isoform of cytochrome P450, can be induced by ethanol, and that ethanol induction of cytochrome P450 2A5 is P450 2E1-dependent.

AIMS

To investigate the role of cytochrome P450 2A5 in alcohol-induced liver injury.

METHODS

Cytochrome P450 2A5-knockout mice and wild type mice were fed the Lieber-Decarli ethanol liquid diet to induce liver injury. Controls were fed the Lieber-Decarli control diet.

RESULTS

After 4 weeks of feeding with Lieber-Decarli diet, ethanol-induced liver injury was enhanced in the knockout mice compared with wild type mice, as indicated by serum transaminases, hepatic fat accumulation (steatosis), and necroinflammation observed in liver sections with Haematoxylin & Eosin staining. Ethanol-induced oxidative stress was also higher in the knockout mice than the wild types. Ethanol feeding induced cytochrome P450 2A5 in wild type mice but not in the knockout mice, while induction of cytochrome P450 2E1 was comparable in the knockout and wild type mice.

CONCLUSION

These results suggest that cytochrome P450 2A5 protects against ethanol-induced oxidative liver injury.

Physical Activity- and Alcohol-dependent Association Between Air Pollution Exposure and Elevated Liver Enzyme Levels: An Elderly Panel Study

OBJECTIVES

The deleterious effects of air pollution on various health outcomes have been demonstrated. However, few studies have examined the effects of air pollution on liver enzyme levels.

METHODS

Blood samples were drawn up to three times between 2008 and 2010 from 545 elderly individuals who regularly visited a community welfare center in Seoul, Korea. Data regarding ambient air pollutants (particulate matter ≤2.5 μm [PM2.5], nitrogen dioxide [NO2], ozone [O3], carbon monoxide, and sulfur dioxide) from monitoring stations were used to estimate air pollution exposure. The effects of the air pollutants on the concentrations of three liver enzymes (aspartate aminotransferase [AST], alanine aminotransferase [ALT], and γ-glutamyltranspeptidase [γ-GTP)]) were evaluated using generalized additive and linear mixed models.

RESULTS

Interquartile range increases in the concentrations of the pollutants showed significant associations of PM2.5 with AST (3.0% increase, p=0.0052), ALT (3.2% increase, p=0.0313), and γ-GTP (5.0% increase, p=0.0051) levels; NO2 with AST (3.5% increase, p=0.0060) and ALT (3.8% increase, p=0.0179) levels; and O3 with γ-GTP (5.3% increase, p=0.0324) levels. Significant modification of these effects by exercise and alcohol consumption was found (p for interaction <0.05). The effects of air pollutants were greater in non-exercisers and heavy drinkers.

CONCLUSIONS

Short-term exposure to air pollutants such as PM2.5, NO2, and O3 is associated with increased liver enzyme levels in the elderly. These adverse effects can be reduced by exercising regularly and abstinence from alcohol.

HIV-1, HCV and alcohol in the CNS: potential interactions and effects on neuroinflammation

Approximately 25% of the HIV-1 positive population is also infected with HCV. The effects of alcohol on HIV-1 or HCV infection have been a research topic of interest due to the high prevalence of alcohol use in these infected patient populations. Although it has long been known that HIV-1 infects the brain, it has only been a little more than a decade since HCV infection of the CNS has been characterized. Both viruses are capable of infecting and replicating in microglia and increasing the expression of proinflammatory cytokines and chemokines, including IL-6 and IL-8. Investigations focusing on the effects of HIV-1, HCV or alcohol on neuroinflammation have demonstrated that these agents are capable of acting through overlapping signaling pathways, including MAPK signaling molecules. In addition, HIV-1, HCV and alcohol have been demonstrated to increase permeability of the blood-brain barrier. Patients infected with either HIV-1 or HCV, or those who use alcohol, exhibit metabolic abnormalities in the CNS that result in altered levels of n-acetyl aspartate, choline and creatine in various regions of the brain. Treatment of HIV/HCV co-infection in alcohol users is complicated by drug-drug interactions, as well as the effects of alcohol on drug metabolism. The drug-drug interactions between the antiretrovirals and the antivirals, as well as the effects of alcohol on drug metabolism, complicate existing models of CNS penetration, making it difficult to assess the efficacy of treatment on CNS infection.

Prenatal antidepressant exposure associated with CYP2E1 DNA methylation change in neonates

Some but not all neonates are affected by prenatal exposure to serotonin reuptake inhibitor antidepressants (SRI) and maternal mood disturbances. Distinguishing the impact of these 2 exposures is challenging and raises critical questions about whether pharmacological, genetic, or epigenetic factors can explain the spectrum of reported outcomes. Using unbiased DNA methylation array measurements followed by a detailed candidate gene approach, we examined whether prenatal SRI exposure was associated with neonatal DNA methylation changes and whether such changes were associated with differences in birth outcomes. Prenatal SRI exposure was first associated with increased DNA methylation status primarily at CYP2E1(β(Non-exposed) = 0.06, β(SRI-exposed) = 0.30, FDR = 0); however, this finding could not be distinguished from the potential impact of prenatal maternal depressed mood. Then, using pyrosequencing of CYP2E1 regulatory regions in an expanded cohort, higher DNA methylation status--both the mean across 16 CpG sites (P < 0.01) and at each specific CpG site (P < 0.05)--was associated with exposure to lower 3rd trimester maternal depressed mood symptoms only in the SRI-exposed neonates, indicating a maternal mood x SRI exposure interaction. In addition, higher DNA methylation levels at CpG2 (P = 0.04), CpG9 (P = 0.04) and CpG10 (P = 0.02), in the interrogated CYP2E1 region, were associated with increased birth weight independently of prenatal maternal mood, SRI drug exposure, or gestational age at birth. Prenatal SRI antidepressant exposure and maternal depressed mood were associated with altered neonatal CYP2E1 DNA methylation status, which, in turn, appeared to be associated with birth weight.

The assessment of an in-vitro model for evaluating the role of PARP in ethanol-mediated hepatotoxicity

This investigation aims to assess whether the hepatocellular carcinoma cell line, HepG2, is an appropriate model to assess the role of poly (ADP-ribose) polymerase (PARP) during acute ethanol toxicosis. HepG2 cells were dosed with graded concentrations of ethanol, ranging from 100 mM to 800 mM, for 6 hours to assess PARP activity induction, while another parallel experiment examined cellular damage via medium aspartate aminotransferase activity and cellular viability via MTT reduction. Aspartate aminotransferase activity was significantly elevated at 600 mM ethanol (FOLD; P < 0.01), with further increases at the 800 mM dose (1.43 fold; P < 0.001), compared to controls. Cellular viability was not significantly decreased compared to controls among all dose groups. PARP activity measured in total cell lysates showed a significant decreasing trend with respect to ethanol dose, reaching statistical significance at the 100 mM dose group (P < 0.05). Paradoxically, exposure to 50 μM etoposide (Positive apoptosis-inducing control) did not demonstrate significant PARP activity ablation. When analyzing PARP activity observation temporally, a significant correlation (R(2) =0.5314) was observed between activity and assay sequence. Overall, a clear HepG2 insensitivity to ethanol was observed.

Determining antioxidant activities of lactobacilli cell-free supernatants by cellular antioxidant assay: a comparison with traditional methods

Antioxidant activity of lactic acid bacteria is associated with multiple health-protective effects. Traditional indexes of chemical antioxidant activities poorly reflect the antioxidant effects of these bacteria in vivo. Cellular antioxidant activity (CAA) assay was used in this study to determine the antioxidant activity of cell-free supernatants (CFSs) of 10 Lactobacillus strains. The performance of the CAA assay was compared with that of four chemical antioxidant activity assays, namely, DPPH radical scavenging, hydroxyl radical scavenging (HRS), reducing power (RP), and inhibition of linoleic acid peroxidation (ILAP). Results of the CAA assay were associated with those of DPPH and ILAP assays, but not with those of RP and HRS assays. The inter- and intra-specific antioxidant activities of CFS were characterized by chemical and CAA assays. L. rhamnosus CCFM 1107 displayed a high antioxidative effect similar to positive control L. rhamnosus GG ATCC 53103 in all of the assays. The CAA assay is a potential method for the detection of antioxidant activities of lactobacilli CFSs.

Hepatoprotective effect of kaempferol against alcoholic liver injury in mice

Kaempferol is a biologically active component present in various plants. The hepatoprotective effect of kaempferol in drug-induced liver injury has been proven, while its effect against alcoholic liver injury (ALI) remains unclear. Hence, the present study aimed to evaluate the effect of kaempferol against ALI in mice. The experimental ALI mice model was developed and the mice were treated with different doses of kaempferol for 4 weeks. The liver functions were observed by monitoring the following parameters: Aspartate aminotransferase (AST/GOT) and alanine aminotransferase (ALT/GPT) levels in serum; histopathological studies of liver tissue; oxidative stress by hydrogen peroxide (H2O2), superoxide dismutase (SOD) and glutathione (GSH); the lipid peroxidation status by malondialdehyde (MDA) and lipid accumulation by triglyceride (TG) level in serum; and the expression levels and activities of a key microsomal enzyme cytochrome 2E1 (CYP2E1), by both in vitro and in vivo methods. The ALI mice (untreated) showed clear symptoms of liver injury, such as significantly increased levels of oxidative stress, lipid peroxidation and excessive CYP2E1 expression and activity. The mice treated with different kaempferol dosages exhibited a significant decrease in the oxidative stress as well as lipid peroxidation, and increased anti-oxidative defense activity. The kaempferol treatment has significantly reduced the expression level and activity of hepatic CYP2E1, thus indicating that kaempferol could down regulate CYP2E1. These findings show the hepatoprotective properties of kaempferol against alcohol-induced liver injury by attenuating the activity and expression of CYP2E1 and by enhancing the protective role of anti-oxidative defense system.

Hepatoprotective Evaluation of Ganoderma lucidum Pharmacopuncture: In vivo Studies of Ethanol-induced Acute Liver Injury

OBJECTIVES

Alcohol abuse is a public issue and one of the major causes of liver disease worldwide. This study was aimed at investigating the protective effect of Ganoderma lucidum pharmacopuncture (GLP) against hepatotoxicity induced by acute ethanol (EtOH) intoxication in rats.

METHODS

Sprague-Dawley (SD) rats were divided into 4 groups of 8 animals each: normal, control, normal saline pharmacopuncture (NP) and GLP groups. The control, NP and GLP groups received ethanol orally. The NP and the GLP groups were treated daily with injections of normal saline and Ganoderma lucidum extract, respectively. The control group received no treatment. The rats in all groups, except the normal group, were intoxicated for 6 hours by oral administration of EtOH (6 g/kg BW). The same volume of distilled water was administered to the rats in the normal group. Two local acupoints were used: Qimen (LR14) and Taechung (LR3). A histopathological analysis was performed, and the liver function and the activities of antioxidant enzymes were assessed.

RESULTS

GLP treatment reduced the histological changes due to acute liver injury induced by EtOH and significantly reduced the increase in the alanine aminotransferase (ALT) enzyme; however, it had an insignificant effect in reducing the increase in aspartate aminotransferase (AST) enzyme. It also significantly ameliorated the superoxide dismutase (SOD) and the catalase (CAT) activities.

CONCLUSION

The present study suggests that GLP treatment is effective in protecting against ethanol-induced acute hepatic injury in SD rats by modulating the activities of ethanol-metabolizing enzymes and by attenuating oxidative stress.

Isoaspartate, carbamoyl phosphate synthase-1, and carbonic anhydrase-III as biomarkers of liver injury

We had previously shown that alcohol consumption can induce cellular isoaspartate protein damage via an impairment of the activity of protein isoaspartyl methyltransferase (PIMT), an enzyme that triggers repair of isoaspartate protein damage. To further investigate the mechanism of isoaspartate accumulation, hepatocytes cultured from control or 4-week ethanol-fed rats were incubated in vitro with tubercidin or adenosine. Both these agents, known to elevate intracellular S-adenosylhomocysteine levels, increased cellular isoaspartate damage over that recorded following ethanol consumption in vivo. Increased isoaspartate damage was attenuated by treatment with betaine. To characterize isoaspartate-damaged proteins that accumulate after ethanol administration, rat liver cytosolic proteins were methylated using exogenous PIMT and (3)H-S-adenosylmethionine and proteins resolved by gel electrophoresis. Three major protein bands of ∼ 75-80 kDa, ∼ 95-100 kDa, and ∼ 155-160 kDa were identified by autoradiography. Column chromatography used to enrich isoaspartate-damaged proteins indicated that damaged proteins from ethanol-fed rats were similar to those that accrued in the livers of PIMT knockout (KO) mice. Carbamoyl phosphate synthase-1 (CPS-1) was partially purified and identified as the ∼ 160 kDa protein target of PIMT in ethanol-fed rats and in PIMT KO mice. Analysis of the liver proteome of 4-week ethanol-fed rats and PIMT KO mice demonstrated elevated cytosolic CPS-1 and betaine homocysteine S-methyltransferase-1 when compared to their respective controls, and a significant reduction of carbonic anhydrase-III (CA-III) evident only in ethanol-fed rats. Ethanol feeding of rats for 8 weeks resulted in a larger (∼ 2.3-fold) increase in CPS-1 levels compared to 4-week ethanol feeding indicating that CPS-1 accumulation correlated with the duration of ethanol consumption. Collectively, our results suggest that elevated isoaspartate and CPS-1, and reduced CA-III levels could serve as biomarkers of hepatocellular injury.

Antioxidant status and Na(+), K (+)-ATPase activity in freshwater fish Carassius auratus exposed to different combustion products of Nafion 117 membrane: an integrated biomarker approach

Nafion 117 membrane (N117), an important polymer electrolyte membrane (PEM), has been widely applied in numerous chemical technologies. Its increasing production and utilization will inevitably lead to the problem of waste disposal, with incineration as an important method. However, toxicity data of its combustion products on aquatic organisms have been seldom reported. The present study was therefore conducted to investigate the antioxidant response and Na(+), K(+)-ATPase activity in liver of Carassius auratus exposed to different combustion products of N117 for 5, 15, and 30 days. The concentrations of fluorine ion (F(-)) in the aquaria among the exposure durations were analyzed using the ion chromatography system. The results showed that these treatments have the capability to induce oxidative stress and suppress Na(+), K(+)-ATPase activity, as indicated by some significant alterations on these measured toxicity end-points in fish liver. According to the integrated biomarker response (IBR) index, the toxicity intensity of these experimental treatments was tentatively ranked. Taken together, these observations provided some preliminary data on the potential toxicity of the combustion products of N117 on aquatic organisms and could fill the information gaps in the toxicity database of the current-use PEM.

Nrf2-mediated antioxidant response by ethanolic extract of Sida cordifolia provides protection against alcohol-induced oxidative stress in liver by upregulation of glutathione metabolism

Objective The study aimed to evaluate the antioxidant property of ethanolic extract of Sida cordifolia (SAE) on alcohol-induced oxidative stress and to elucidate its mechanism of action. Methods Male albino rats of the Sprague-Dawley strain were grouped into four: (1) control, (2) alcohol (4 g/kg body weight), (3) SAE (50 mg/100 g body weight), and (4) alcohol (4 g/kg body weight) + SAE (50 mg/100 g body weight). Alcohol and SAE were given orally each day by gastric intubation. The duration of treatment was 90 days. Results The activities of toxicity markers in liver and serum increased significantly in alcohol-treated rats and to a lesser extent in the group administered SAE + alcohol. The activity of alcohol dehydrogenase and the reactive oxygen species level were increased significantly in alcohol-treated rats but attenuated in the SAE co-administered group. Oxidative stress was increased in alcohol-treated rats as evidenced by the lowered activities of antioxidant enzymes, decreased level of reduced glutathione (GSH), increased lipid peroxidation products, and decreased expression of γ-glutamyl cysteine synthase in liver. The co-administration of SAE with alcohol almost reversed these changes. The activity of glutathione-S-transferase and translocation of Nrf2 from cytosol to nucleus in the liver was increased in both the alcohol and alcohol + SAE groups, but the maximum changes were observed in the latter group. Discussion The SAE most likely elicits its antioxidant potential by reducing oxidative stress, enhancing the translocation of Nrf2 to nucleus and thereby regulating glutathione metabolism, leading to enhanced GSH content.

Chronic alcohol consumption potentiates the development of diabetes through pancreatic β-cell dysfunction

Chronic ethanol consumption is well established as a major risk factor for type-2 diabetes (T2D), which is evidenced by impaired glucose metabolism and insulin resistance. However, the relationships between alcohol consumption and the development of T2D remain controversial. In particular, the direct effects of ethanol consumption on proliferation of pancreatic β-cell and the exact mechanisms associated with ethanol-mediated β-cell dysfunction and apoptosis remain elusive. Although alcoholism and alcohol consumption are prevalent and represent crucial public health problems worldwide, many people believe that low-to-moderate ethanol consumption may protect against T2D and cardiovascular diseases. However, the J- or U-shaped curves obtained from cross-sectional and large prospective studies have not fully explained the relationship between alcohol consumption and T2D. This review provides evidence for the harmful effects of chronic ethanol consumption on the progressive development of T2D, particularly with respect to pancreatic β-cell mass and function in association with insulin synthesis and secretion. This review also discusses a conceptual framework for how ethanol-produced peroxynitrite contributes to pancreatic β-cell dysfunction and metabolic syndrome.

Effects of ethanol on the expression of caveolin-1 in HepG2 cells

This study aimed to investigate the effects of ethanol on the expression of caveolin‑1 (CAV‑1) in HepG2 hepatocarcinoma cells. Ethanol‑treated HepG2 cells were investigated using the in vitro model to determine whether ethanol can influence the expression of CAV‑1. Cell viability was measured using the colorimetric 3‑(4, 5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Expression of CAV‑1 was detected using western blot analysis. Quantitative PCR (qPCR) was used to determine CAV‑1 mRNA levels. The distribution of CAV‑1 in HepG2 cells was analyzed using immunofluorescence. The MTT assay results revealed that cell viability was not altered at ethanol concentrations of <1.0%, while ethanol concentrations >1.0% caused cell shedding, but not cell fragmentation. Western blot analysis showed significant differences in the levels of CAV‑1 expression between the control group and the 1.0% ethanol‑treated group at 6, 12 and 24 h (all P<0.05). qPCR showed significant differences in the expression levels of caveolin‑1 mRNA between the control group and the 1.0% ethanol‑treated group at 6 h, 12 h and 24 h (all P<0.05). Immunofluorescence demonstrated that CAV‑1 was distributed discontinuously at the boundaries of HepG2 cells. The results indicate that ethanol may increase the expression of CAV‑1 in HepG2 cells.

Sweet grass protection against oxidative stress formation in the rat brain

The aims of this study were to investigate the influences of sweet grass on chronic ethanol-induced oxidative stress in the rat brain. Chronic ethanol intoxication decreased activities and antioxidant levels resulting in enhanced lipid peroxidation. Administration of sweet grass solution to ethanol-intoxicated rats partially normalized the activity activities of Cu,Zn-superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, as well as levels of reduced glutathione and vitamins C, E, and A. Sweet grass also protected unsaturated fatty acids (arachidonic and docosahexaenoic) from oxidations and decreased levels of lipid peroxidation products: 4-hydroxynonenal, isoprostanes, and neuroprostanes. The present in vivo study confirms previous in vitro data demonstrating the bioactivity of sweet grass and suggests a possible role for sweet grass in human health protection from deleterious consequences associated with oxidative stress formation.

Gut-liver axis in alcoholic liver disease

Alcoholic liver disease (ALD) has been among the leading causes of cirrhosis and liver-related death worldwide for decades. Early discoveries in alcoholic liver disease identified increased levels of bacterial endotoxin in the portal circulation, suggesting a role for gut-derived toxins in ALD. Indeed, alcohol consumption can disrupt the intestinal epithelial barrier and result in increased gut permeability that increasingly is recognized as a major factor in ALD. Bacterial endotoxin, lipopolysaccharide, is a prototypic microbe-derived inflammatory signal that contributes to inflammation in ALD through activation of the Toll-like receptor 4. Recent studies also have shown that alcohol consumption is associated with alterations in the gut microbiome, and the dysbalance of pathogenic and commensal organisms in the intestinal microbiome may contribute to the abnormal gut-liver axis in ALD. Indeed, bacterial decontamination improves ALD both in human and animal models. This short review summarizes recent findings and highlights emerging trends in the gut-liver axis relevant to ALD.

Identification of hepatoprotective xanthones from the pericarps of Garcinia mangostana, guided with tert-butyl hydroperoxide induced oxidative injury in HL-7702 cells

This study identified γ-mangostin from the pericarps of Garcinia mangostana as a potential hepatoprotective agent.

Metabolomics approach to identify therapeutically potential biomarkers of the Zhi-Zi-Da-Huang decoction effect on the hepatoprotective mechanism

A NMR-based metabolomics approach was applied to find potential plasma and liver biomarkers responsible for the hepatoprotective effects of Zhi-Zi-Da-Huang decoction (ZZDHD).

Serum metabolomic profiling in acute alcoholic hepatitis identifies multiple dysregulated pathways

BACKGROUND AND OBJECTIVES

While animal studies have implicated derangements of global energy homeostasis in the pathogenesis of acute alcoholic hepatitis (AAH), the relevance of these findings to the development of human AAH remains unclear. Using global, unbiased serum metabolomics analysis, we sought to characterize alterations in metabolic pathways associated with severe AAH and identify potential biomarkers for disease prognosis.

METHODS

This prospective, case-control study design included 25 patients with severe AAH and 25 ambulatory patients with alcoholic cirrhosis. Serum samples were collected within 24 hours of the index clinical encounter. Global, unbiased metabolomics profiling was performed. Patients were followed for 180 days after enrollment to determine survival.

RESULTS

Levels of 234 biochemicals were altered in subjects with severe AAH. Random-forest analysis, principal component analysis, and integrated hierarchical clustering methods demonstrated that metabolomics profiles separated the two cohorts with 100% accuracy. Severe AAH was associated with enhanced triglyceride lipolysis, impaired mitochondrial fatty acid beta oxidation, and upregulated omega oxidation. Low levels of multiple lysolipids and related metabolites suggested decreased plasma membrane remodeling in severe AAH. While most measured bile acids were increased in severe AAH, low deoxycholate and glycodeoxycholate levels indicated intestinal dysbiosis. Several changes in substrate utilization for energy homeostasis were identified in severe AAH, including increased glucose consumption by the pentose phosphate pathway, altered tricarboxylic acid (TCA) cycle activity, and enhanced peptide catabolism. Finally, altered levels of small molecules related to glutathione metabolism and antioxidant vitamin depletion were observed in patients with severe AAH. Univariable logistic regression revealed 15 metabolites associated with 180-day survival in severe AAH.

CONCLUSION

Severe AAH is characterized by a distinct metabolic phenotype spanning multiple pathways. Metabolomics profiling revealed a panel of biomarkers for disease prognosis, and future studies are planned to validate these findings in larger cohorts of patients with severe AAH.

Molecular mechanisms of the microsomal mixed function oxidases and biological and pathological implications

The cytochrome P450 mixed function oxidase enzymes play a major role in the metabolism of important endogenous substrates as well as in the biotransformation of xenobiotics. The liver P450 system is the most active in metabolism of exogenous substrates. This review briefly describes the liver P450 (CYP) mixed function oxidase system with respect to its enzymatic components and functions. Electron transfer by the NADPH-P450 oxidoreductase is required for reduction of the heme of P450, necessary for binding of molecular oxygen. Binding of substrates to P450 produce substrate binding spectra. The P450 catalytic cycle is complex and rate-limiting steps are not clear. Many types of chemical reactions can be catalyzed by P450 enzymes, making this family among the most diverse catalysts known. There are multiple forms of P450s arranged into families based on structural homology. The major drug metabolizing CYPs are discussed with respect to typical substrates, inducers and inhibitors and their polymorphic forms. The composition of CYPs in humans varies considerably among individuals because of sex and age differences, the influence of diet, liver disease, presence of potential inducers and/or inhibitors. Because of such factors and CYP polymorphisms, and overlapping drug specificity, there is a large variability in the content and composition of P450 enzymes among individuals. This can result in large variations in drug metabolism by humans and often can contribute to drug–drug interactions and adverse drug reactions. Because of many of the above factors, especially CYP polymorphisms, there has been much interest in personalized medicine especially with respect to which CYPs and which of their polymorphic forms are present in order to attempt to determine what drug therapy and what dosage would reflect the best therapeutic strategy in treating individual patients.

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The CYP P450 system is important in metabolism of endogenous substrates and drugs.

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About 150 forms of CYPs have been identified and they are grouped into families.

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CYPs catalyze a wide variety of reactions and are among the most diverse catalysts known.

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Electrons are passed to the CYP via NADPH+NADPH-cytochrome P450 reductase.

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Metabolism of certain compounds by CYPs generate reactive intermediates which are toxic.

Over-activation of TLR5 signaling by high-dose flagellin induces liver injury in mice

Flagellin is a potent activator of a broad range of cell types that are involved in innate and adaptive immunity. Therefore, it is a good adjuvant candidate for vaccines, and it might function as a biological protectant against both major acute radiation syndrome during cancer radiotherapy and a mitigator of radiation emergencies. However, accumulating evidence has implicated flagellin in the occurrence of some inflammatory diseases, such as acute lung inflammation, cardiovascular collapse and inflammatory bowel disease. The aim of this study was to elucidate whether only flagellin-TLR5 signaling activation plays a role in the pathophysiology of liver or whether some other flagellin activity also contributes to liver injury either via bacterial infections or during clinical applications. Recombinant flagellin proteins with or without TLR5-stimulating activity were used to evaluate the role of flagellin-TLR5 signaling in liver injury in wild-type and TLR5 KO mice. Gross lesions and large areas of hepatocellular necrosis were observed in liver tissue 12 h after the intraperitoneal administration of 100 or 200 µg flagellin (FliC) in a dose- and time-dependent manner in wild-type mice, but not in TLR5 KO mice. Deletion of the N-terminal or TLR5 binding domain of flagellin inhibited flagellin-induced inflammatory responses and the subsequent acute liver function abnormality and damage. These data confirmed that flagellin is an essential determinant of liver injury and demonstrated that the over-activation of TLR5 signaling by high-dose flagellin caused acute inflammatory responses, neutrophil accumulation and oxidative stress in the liver, which contributes to the progression and severity of flagellin-induced liver injury.

Chunggan extract, a traditional herbal formula, ameliorated alcohol-induced hepatic injury in rat model

AIM: To evaluate protective effects of Chunggan extract (CGX), a traditional herbal formula, under 4 wk of alcohol consumption-induced liver injury.

METHODS: Male Sprague-Dawley Rats were orally administered 30% ethanol daily for 4 wk with or without CGX. The pharmaceutical properties were assessed through liver enzymes, histopathology, fibrogenic cytokines, and alcohol metabolism in hepatic tissues as well as by in vitro experiment using HSC-T6 cells.

RESULTS: Four weeks of alcohol consumption notably increased liver enzymes and malondialdehyde levels in serum and hepatic tissue. CGX not only prevented the collagen deposition determined by histopathology and hydroxyproline content, but also normalized transforming growth factor-beta, platelet-derived growth factor-beta and connective tissue growth factor at the gene expression and protein levels in liver tissue. Moreover, CGX treatment also significantly normalized the abnormal changes in gene expression profiles of extracellular matrix proteins, matrix metalloproteinase and their inhibitors, alcohol metabolism, and inflammatory reactions. In the acetaldehyde-stimulated HSC-T6 cells, CGX considerably inhibited collagen production and normalized fibrogenic cytokines in both gene expression and protein levels.

CONCLUSION: The present study evidenced that CGX has hepatoprotective properties via modulation of fibrogenic cytokines and alcohol metabolism in alcoholic liver injury.

Review of natural products with hepatoprotective effects

The liver is one of the most important organs in the body, performing a fundamental role in the regulation of diverse processes, among which the metabolism, secretion, storage, and detoxification of endogenous and exogenous substances are prominent. Due to these functions, hepatic diseases continue to be among the main threats to public health, and they remain problems throughout the world. Despite enormous advances in modern medicine, there are no completely effective drugs that stimulate hepatic function, that offer complete protection of the organ, or that help to regenerate hepatic cells. Thus, it is necessary to identify pharmaceutical alternatives for the treatment of liver diseases, with the aim of these alternatives being more effective and less toxic. The use of some plants and the consumption of different fruits have played basic roles in human health care, and diverse scientific investigations have indicated that, in those plants and fruits so identified, their beneficial effects can be attributed to the presence of chemical compounds that are called phytochemicals. The present review had as its objective the collecting of data based on research conducted into some fruits (grapefruit, cranberries, and grapes) and plants [cactus pear (nopal) and cactus pear fruit, chamomile, silymarin, and spirulina], which are consumed frequently by humans and which have demonstrated hepatoprotective capacity, as well as an analysis of a resin (propolis) and some phytochemicals extracted from fruits, plants, yeasts, and algae, which have been evaluated in different models of hepatotoxicity.

Antioxidant and hepatoprotective effect of (-)-epigallocatechin 3-O-(3-O-methyl) gallate (EGCG3″Me) from Chinese oolong tea

(-)-Epigallocatechin 3-O-(3-O-methyl) gallate (EGCG3″Me) has exhibited various biological activities in oolong tea. However, little information about its hepatoprotective activity is available. The objectives of the present study, therefore, were to determine the hepatoprotective activity of EGCG3″Me. First, high-purity EGCG3″Me was prepared from Chinese oolong tea by column chromatography. In antioxidant assay in vitro, EGCG3″Me exhibited potential antioxidant activity. For hepatoprotective activity in vitro, it was observed that EGCG3″Me effectively alleviated the changes induced by alcohol in a concentration-dependent manner. For hepatoprotective activity in vivo, the administration of EGCG3″Me at a dose of 100 mg/kg BW per day significantly decreased the serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) from 64.6 ± 3.17 and 97.6 ± 3.78 to 39.6 ± 2.72 and 59.6 ± 3.02 U/L, decreased the liver level of malondialdehyde (MDA) from 1.14 ± 0.08 to 0.77 ± 0.03 nmol/mg protein, and remarkably restored the liver activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) from 247 ± 20.1 U/mg and 6.12 ± 0.17 nmol/mg protein to 261 ± 9.98 U/mg and 8.10 ± 0.03 nmol/mg protein, respectively, in alcohol-induced liver injury mice. This suggested that the protective effect of EGCG3″Me against alcohol-induced liver injury is possibly via its antioxidant activity to protect biological systems against oxidative stress.

Alcohol drinking and mammary cancer: Pathogenesis and potential dietary preventive alternatives

Alcohol consumption is associated with an increased risk of breast cancer, increasing linearly even with a moderate consumption and irrespectively of the type of alcoholic beverage. It shows no dependency from other risk factors like menopausal status, oral contraceptives, hormone replacement therapy, or genetic history of breast cancer. The precise mechanism for the effect of drinking alcohol in mammary cancer promotion is still far from being established. Studies by our laboratory suggest that acetaldehyde produced in situ and accumulated in mammary tissue because of poor detoxicating mechanisms might play a role in mutational and promotional events. Additional studies indicated the production of reactive oxygen species accompanied of decreases in vitamin E and GSH contents and of glutathione transferase activity. The resulting oxidative stress might also play a relevant role in several stages of the carcinogenic process. There are reported in literature studies showing that plasmatic levels of estrogens significantly increased after alcohol drinking and that the breast cancer risk is higher in receptor ER-positive individuals. Estrogens are known that they may produce breast cancer by actions on ER and also as chemical carcinogens, as a consequence of their oxidation leading to reactive metabolites. In this review we introduce our working hypothesis integrating the acetaldehyde and the oxidative stress effects with those involving increased estrogen levels. We also analyze potential preventive actions that might be accessible. There remains the fact that alcohol drinking is just one of the avoidable causes of breast cancer and that, at present, the suggested acceptable dose for prevention of this risk is of one drink per day.

Regulation of the effects of CYP2E1-induced oxidative stress by JNK signaling

The generation of excessive amounts of reactive oxygen species (ROS) leads to cellular oxidative stress that underlies a variety of forms of hepatocyte injury and death including that from alcohol. Although ROS can induce cell damage through direct effects on cellular macromolecules, the injurious effects of ROS are mediated largely through changes in signal transduction pathways such as the mitogen-activated protein kinase c-Jun N-terminal kinase (JNK). In response to alcohol, hepatocytes have increased levels of the enzyme cytochrome P450 2E1 (CYP2E1) which generates an oxidant stress that promotes the development of alcoholic steatosis and liver injury. These effects are mediated in large part through overactivation of JNK that alters cell death pathways. Targeting the JNK pathway or its downstream effectors may be a useful therapeutic approach to the oxidative stress generated by CYP2E1 in alcoholic liver disease.

HBx inhibits CYP2E1 gene expression via downregulating HNF4α in human hepatoma cells

CYP2E1, one of the cytochrome P450 mixed-function oxidases located predominantly in liver, plays a key role in metabolism of xenobiotics including ethanol and procarcinogens. Recently, down-expression of CYP2E1 was found in hepatocellular carcinoma (HCC) with the majority to be chronic hepatitis B virus (HBV) carriers. In this study, we tested a hypothesis that HBx may inhibit CYP2E1 gene expression via hepatocyte nuclear factor 4α (HNF4α). By enforced HBx gene expression in cultured HepG2 cells, we determined the effect of HBx on CYP2E1 mRNA and protein expression. With a bioinformatics analysis, we found a consensus HNF-4α binding sequence located on −318 to −294 bp upstream of human CYP2E1 promoter. Using reporter gene assay and site-directed mutagenesis, we have shown that mutation of this site dramatically decreased CYP2E1 promoter activity. By silencing endogenous HNF-4α, we have further validated knockdown of HNF-4α significantly decreased CYP2E1expression. Ectopic overexpression of HBx in HepG2 cells inhibits HNF-4α expression, and HNF-4α levels were inversely correlated with viral proteins both in HBV-infected HepG2215 cells and as well as HBV positive HCC liver tissues. Moreover, the HBx-induced CYP2E1 reduction could be rescued by ectopic supplement of HNF4α protein expression. Furthermore, human hepatoma cells C34, which do not express CYP2E1, shows enhanced cell growth rate compared to E47, which constitutively expresses CYP2E1. In addition, the significantly altered liver proteins in CYP2E1 knockout mice were detected with proteomics analysis. Together, HBx inhibits human CYP2E1 gene expression via downregulating HNF4α which contributes to promotion of human hepatoma cell growth. The elucidation of a HBx-HNF4α-CYP2E1 pathway provides novel insight into the molecular mechanism underlining chronic HBV infection associated hepatocarcinogenesis.

Modulation of GSH with exogenous agents leads to changes in glyoxalase 1 enzyme activity in VL-17A cells exposed to chronic alcohol plus high glucose

Gluthathione (GSH) is a major cellular antioxidant. The present study utilizing VL-17A cells exposed to chronic alcohol plus high glucose investigated the changes in oxidative stress, toxicity, and glyoxalase 1 activity as a detoxification pathway due to changes in GSH level through GSH supplementation with N-acetyl cysteine (NAC) or ursodeoxycholic acid (UDCA) and its depletion through buthionine sulfoximine (BSO) or diethyl maleate (DEM). Glyoxalase 1 plays an important role in detoxification of methylglyoxal which is formed as a precursor of advanced glycated end products formed due to high glucose mediated oxidative stress. Significant changes in glyoxalase 1 activity utilizing methylglyoxal or glyoxal as substrates occurred with NAC or UDCA or BSO or DEM supplementation in chronic alcohol plus high glucose treated VL-17A cells. NAC or UDCA administration in chronic alcohol plus high glucose treated VL-17A cells increased viability and decreased ROS levels, lipid peroxidation and 3-nitrotyrosine adduct formation. Similarly, GSH depletion with BSO or DEM had an opposite effect on the parameters in chronic alcohol plus high glucose treated VL-17A cells. In conclusion, modulation of GSH with NAC or UDCA or BSO or DEM leads to significant changes in oxidative stress, glyoxalase 1 enzyme activity and toxicity in chronic alcohol plus high glucose treated VL-17A cells.

Xanthohumol, a prenylated flavonoid from hops (Humulus lupulus L.), protects rat tissues against oxidative damage after acute ethanol administration

Ethanol-mediated free radical generation is directly involved in alcoholic liver disease. In addition, chronic alcohol bingeing also induces pathological changes and dysfunction in multi-organs. In the present study, the protective effect of xanthohumol (XN) on ethanol-induced damage was evaluated by determining antioxidative parameters and stress oxidative markers in liver, kidney, lung, heart and brain of rats. An acute treatment (4 g/kg b.w.) of ethanol resulted in the depletion of superoxide dismutase, catalase and glutathione S-transferase activities and reduced glutathione content. This effect was accompanied by the increased activity of tissue damage marker enzymes (glutamate oxaloacetate transaminase, glutamate pyruvate transaminase and lactate dehydrogenase) and a significant increase in lipid peroxidation and hydrogen peroxide concentrations. Pre-treatment with XN protected rat tissues from ethanol-induced oxidative imbalance and partially mitigated the levels to nearly normal levels in all tissues checked. This effect was dose dependent, suggesting that XN reduces stress oxidative and protects rat tissues from alcohol-induced injury.

Effects of herbal infusions, tea and carbonated beverages on alcohol dehydrogenase and aldehyde dehydrogenase activity

Various alcoholic beverages containing different concentrations of ethanol are widely consumed, and excessive alcohol consumption may result in serious health problems. The consumption of alcoholic beverages is often accompanied by non-alcoholic beverages, such as herbal infusions, tea and carbonated beverages to relieve drunk symptoms. The aim of this study was to supply new information on the effects of these beverages on alcohol metabolism for nutritionists and the general public, in order to reduce problems associated with excessive alcohol consumption. The effects of 57 kinds of herbal infusions, tea and carbonated beverages on alcohol dehydrogenase and aldehyde dehydrogenase activity were evaluated. Generally, the effects of these beverages on alcohol dehydrogenase and aldehyde dehydrogenase activity are very different. The results suggested that some beverages should not be drank after excessive alcohol consumption, and several beverages may be potential dietary supplements for the prevention and treatment of problems related to excessive alcohol consumption.

Protective effect of Red Bull drinks against chronic alcoholic injury in rats

AIM: To observe whether Red Bull drinks have a protective effect against chronic alcoholic liver injury in rats.

METHODS: Chronic alcoholic liver injury was induced in rats by intragastric administration of alcohol (56°). Rats were divided into three groups and were given alcohol (positive group), 0.9% saline (control group), and alcohol plus Red Bull drinks (experimental group), respectively. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and the activities of superoxide dismutase (SOD), malondialdehyde (MDA) and metallothionein (MT) were detected by the end of the experiment. Conventional paraffin section of the left lobe was stained with hematoxylin-eosin (HE) to observe pathological changes.

RESULTS: SOD showed significant differences among the three groups (F = 5.793, P = 0.017). SOD was significantly higher in the control group than in the positive group (0.882 ± 0.044 vs 0.649 ± 0.154, P < 0.05), and in the experimental group than in the positive group (0.797 ± 0.097 vs 0.649 ± 0.154, P < 0.05), although there was no significant difference between the positive group and experimental group. Liver pathology showed congestion in individual liver tissues in the positive group, which was not persuasive.

CONCLUSION: Red Bull drinks have an appreciated protective effect against chronic alcoholic liver injury in rats.

Aging and alcohol interact to alter hepatic DNA hydroxymethylation

BACKGROUND

Aging and chronic alcohol consumption are both modifiers of DNA methylation, but it is not yet known whether chronic alcohol consumption also alters DNA hydroxymethylation, a newly discovered epigenetic mark produced by oxidation of methylcytosine. Furthermore, it has not been tested whether aging and alcohol interact to modify this epigenetic phenomenon, thereby having an independent effect on gene expression.

METHODS

Old (18 months) and young (4 months) male C57BL/6 mice were pair-fed either a Lieber-DeCarli liquid diet with alcohol (18% of energy) or an isocaloric Lieber-DeCarli control diet for 5 weeks. Global DNA hydroxymethylation and DNA methylation were analyzed from hepatic DNA using a new liquid chromatography-tandem mass spectrometry method. Hepatic mRNA expression of the Tet enzymes were measured via quantitative real-time polymerase chain reaction.

RESULTS

In young mice, mild chronic alcohol exposure significantly reduced global DNA hydroxymethylation compared with control mice (0.22 ± 0.01 vs. 0.29 ± 0.06%, p = 0.004). Alcohol did not significantly alter hydroxymethylcytosine levels in old mice. Old mice fed the control diet showed decreased global DNA hydroxymethylation compared with young mice fed the control diet (0.24 ± 0.02 vs. 0.29 ± 0.06%, p = 0.04). This model suggests an interaction between aging and alcohol in determining DNA hydroxymethylation (pinteraction  = 0.009). Expression of Tet2 and Tet3 was decreased in the old mice relative to the young (p < 0.005).

CONCLUSIONS

The observation that alcohol alters DNA hydroxymethylation indicates a new epigenetic effect of alcohol. This is the first study demonstrating the interactive effects of chronic alcohol consumption and aging on DNA hydroxymethylation.

Testicular development of male mice offsprings exposed to acrylamide and alcohol during the gestation and lactation period

Acrylamide (Ac) in the foods and alcohol (Al) in the drinks are unavoidable. Several previous studies demonstrated that these substances which are taken into the body via diet may cause adverse effects in the cells. However, there is no study about how Ac and Al may affect the male reproductive system of the offspring when consumed by the mother during pregnancy and lactation. For this purpose, sexual development in male mice was evaluated after intake of 14 mg/kg Ac and 2 g/kg Al from gestation day 6 to postnatal day (PND) 21. The weight of the offspring was reduced at birth and PND 21 for those exposed to Ac and/or Al. The gonadosomatic index of male offsprings was reduced except for the Ac-treated lactation group. Both substances induced multinuclear giant cells, degenerative cells, atrophic tubules, and maturation-arrested tubules, while decreased Leydig, Sertoli, and spermatogenic cell numbers. Lipid peroxidation level and superoxide dismutase enzyme activity increased in both Al-treated and Ac and Al-treated groups. There was only reduction in the catalase activity during the gestation and lactation periods. These findings suggest that consumption of Ac together with Al may induce impairments on testicular spermatogenesis in male offsprings.

Peroxisome proliferator-activated receptor α, a potential therapeutic target for alcoholic liver disease

Alcoholic liver injury represents a progressive process with a range of consequences including hepatic steatosis, steatohepatitis, liver fibrosis, cirrhosis, and hepatocellular carcinoma. Targeting key molecular regulators involved in the development of alcoholic liver injury may be of great value in the prevention of liver injury. Peroxisome proliferator-activated receptor α (PPARα) plays a pivotal role in modulation of hepatic lipid metabolism, oxidative stress, inflammatory response and fibrogenesis. As such, PPARα may be a potential therapeutic target for the treatment of alcoholic liver disease.

Oxidative stress as a crucial factor in liver diseases

Redox state constitutes an important background of numerous liver disorders. The redox state participates in the course of inflammatory, metabolic and proliferative liver diseases. Reactive oxygen species (ROS) are primarily produced in the mitochondria and in the endoplasmic reticulum of hepatocytes via the cytochrome P450 enzymes. Under the proper conditions, cells are equipped with special molecular strategies that control the level of oxidative stress and maintain a balance between oxidant and antioxidant particles. Oxidative stress represents an imbalance between oxidant and antioxidant agents. Hepatocytic proteins, lipids and DNA are among the cellular structures that are primarily affected by ROS and reactive nitrogen species. The process results in structural and functional abnormalities in the liver. Thus, the phenomenon of oxidative stress should be investigated for several reasons. First, it may explain the pathogenesis of various liver disorders. Moreover, monitoring oxidative markers among hepatocytes offers the potential to diagnose the degree of liver damage and ultimately to observe the response to pharmacological therapies. The present report focuses on the role of oxidative stress in selected liver diseases.

Isolation and biological activity of compounds from Garcinia preussii

CONTEXT

Plants of the genus Garcinia (Clusiaceae) are traditionally used to relieve stomachaches, toothaches, and as a chew stick.

OBJECTIVE

In order to determine which compounds were responsible for these activities, a phytochemical investigation of the fruits and leaves of Garcinia preussii Engl. was pursued.

MATERIALS AND METHODS

Plants were extracted by solvents of various polarities. Compounds isolation was then carried out using chromatography methods (medium- and high-pressure liquid chromatography, open column and thin-layer chromatography). The isolated compounds were identified and characterized by using 1D and 2D NMR spectroscopies. The antioxidant activity was evaluated using DPPH(•), ABTS(•-), ALP, and ORAC assays. The antimicrobial activity was assayed against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Enterococcus faecalis by determining the minimum inhibitory concentration (MIC) value. The cytotoxic activity of most of the isolated compounds was evaluated on a small panel of human cancer cell lines (DU145, HeLa, HT-29, and A431) using the XTT method.

RESULTS

The phytochemical investigation of G. preussii led to the isolation of eight known compounds, six benzophenones and two flavonoids. These compounds were tested for their biological activities. 1, 2, 3, 4, 7 and 8 demonstrated a high free radical scavenging activity with ER50 ranging from 0.1 to 0.7. The antimicrobial activity was shown only against Gram-positive bacteria for 1, 4, and 5. A moderate cytotoxic activity with IC50 ranging from 7 to 50 µM was observed, except for 6 which was not active.

CONCLUSION

These results appear to support some of the properties reported for Garcinia species.

Globular adiponectin inhibits ethanol-induced reactive oxygen species production through modulation of NADPH oxidase in macrophages: involvement of liver kinase B1/AMP-activated protein kinase pathway

Adiponectin, an adipokine predominantly secreted from adipocytes, has been shown to play protective roles against chronic alcohol consumption. Although excessive reactive oxygen species (ROS) production in macrophages is considered one of the critical events for ethanol-induced damage in various target tissues, the effect of adiponectin on ethanol-induced ROS production is not clearly understood. In the present study, we investigated the effect of globular adiponectin (gAcrp) on ethanol-induced ROS production and the potential mechanisms underlying these effects of gAcrp in macrophages. Here we demonstrated that gAcrp prevented ethanol-induced ROS production in both RAW 264.7 macrophages and primary murine peritoneal macrophages. Globular adiponectin also inhibited ethanol-induced activation of NADPH oxidase. In addition, gAcrp suppressed ethanol-induced increase in the expression of NADPH oxidase subunits, including Nox2 and p22(phox), via modulation of nuclear factor-κB pathway. Furthermore, pretreatment with compound C, a selective inhibitor of AMPK, or knockdown of AMPK by small interfering RNA restored suppression of ethanol-induced ROS production and Nox2 expression by gAcrp. Finally, we found that gAcrp treatment induced phosphorylation of liver kinase B1 (LKB1), an upstream signaling molecule mediating AMPK activation. Knockdown of LKB1 restored gAcrp-suppressed Nox2 expression, suggesting that LKB1/AMPK pathway plays a critical role in the suppression of ethanol-induced ROS production and activation of NADPH oxidase by gAcrp. Taken together, these results demonstrate that globular adiponectin prevents ethanol-induced ROS production, at least in part, via modulation of NADPH oxidase in macrophages. Further, LKB1/AMPK axis plays an important role in the suppression of ethanol-induced NADPH oxidase activation by gAcrp in macrophages.

Angiotensin II and canonical transient receptor potential-6 activation stimulate release of a signal transducer and activator of transcription 3-activating factor from mouse podocytes

Previous studies have shown that the transcription factor signal transducer and activator of transcription-3 (STAT3) in podocytes plays an important role in progression of HIV nephropathy and in collapsing forms of glomerulonephritis. Here, we have observed that application of 100 nM angiotensin II (Ang II) to cultured podocytes for 6-24 hours causes a marked increase in the phosphorylation of STAT3 on tyrosine Y705 but has no effect on phosphorylation at serine S727. By contrast, Ang II treatment of short periods (20-60 minutes) caused a small but consistent suppression of tyrosine phosphylation of STAT3. A similar biphasic effect was seen after treatment with the diacylglycerol analog 1-oleoyl-2-acetyl-sn-glycerol (OAG), an agent that causes activation of Ca(2+)-permeable canonical transient receptor potential-6 (TRPC6) channels in podocytes. The stimulatory effects of Ang II on STAT3 phosphorylation were abolished by small-interfering RNA knockdown of TRPC6 and also by inhibitors of the Ca(2+)-dependent downstream enzymes calcineurin and Ca(2+)-calmodulin-dependent protein kinase II. The stimulatory effects of Ang II appear to be mediated by secretion and accumulation of an unknown factor into the surrounding medium, as they are no longer detected when medium is replaced every 2 hours even if Ang II is continuously present. By contrast, the inhibitory effect of Ang II on STAT3 phosphorylation persists with frequent medium changes. Experiments with neutralizing and inhibitory antibodies suggest that the STAT3 stimulatory factor secreted from podocytes is not interleukin-6, but also suggest that this factor exerts its actions through a receptor system that requires glycoprotein 130.

Micronuclei in bone marrow and liver in relation to hepatic metabolism and antioxidant response due to coexposure to chloroform, dichloromethane, and toluene in the rat model

Genotoxicity in cells may occur in different ways, direct interaction, production of electrophilic metabolites, and secondary genotoxicity via oxidative stress. Chloroform, dichloromethane, and toluene are primarily metabolized in liver by CYP2E1, producing reactive electrophilic metabolites, and may also produce oxidative stress via the uncoupled CYP2E1 catalytic cycle. Additionally, GSTT1 also participates in dichloromethane activation. Despite the oxidative metabolism of these compounds and the production of oxidative adducts, their genotoxicity in the bone marrow micronucleus test is unclear. The objective of this work was to analyze whether the oxidative metabolism induced by the coexposure to these compounds would account for increased micronucleus frequency. We used an approach including the analysis of phase I, phase II, and antioxidant enzymes, oxidative stress biomarkers, and micronuclei in bone marrow (MNPCE) and hepatocytes (MNHEP). Rats were administered different doses of an artificial mixture of CLF/DCM/TOL, under two regimes. After one administration MNPCE frequency increased in correlation with induced GSTT1 activity and no oxidative stress occurred. Conversely, after three-day treatments oxidative stress was observed, without genotoxicity. The effects observed indicate that MNPCE by the coexposure to these VOCs could be increased via inducing the activity of metabolism enzymes.

Adverse signaling of scavenger receptor class B1 and PGC1s in alcoholic hepatosteatosis and steatohepatitis and protection by betaine in rat

Because scavenger receptor class B type 1 is the cholesterol uptake liver receptor, whereas peroxisome proliferator-activated receptor γ coactivator-1β (PGC-1β) and PGC-1α are critical for lipid synthesis and degradation, we investigated the roles of these signaling molecules in the actions of ethanol-polyunsaturated fatty acids and betaine on hepatosteatosis and steatohepatitis. Ethanol-polyunsaturated fatty acid treatment caused the following: i) hepatosteatosis, as evidenced by increased liver cholesterol and triglycerides, lipid score, and decreased serum adiponectin; ii) marked inhibition of scavenger receptor class B type 1 glycosylation, its plasma membrane localization, and its hepatic cholesterol uptake function; and iii) moderate steatohepatitis, as evidenced by histopathological characteristics, increased liver tumor necrosis factor α and IL-6, decreased glutathione, and elevated serum alanine aminotransferase. These actions of ethanol involved up-regulated PGC-1β, sterol regulatory element-binding proteins 1c and 2, acetyl-CoA carboxylase, and HMG-CoA reductase mRNAs/proteins and inactive non-phosphorylated AMP kinase; and down-regulated silence regulator gene 1 and PGC-1α mRNA/proteins and hepatic fatty acid oxidation. Betaine markedly blunted all these actions of ethanol on hepatosteatosis and steatohepatitis. Therefore, we conclude that ethanol-mediated impaired post-translational modification, trafficking, and function of scavenger receptor class B type 1 may account for alcoholic hyperlipidemia. Up-regulation of PGC-1β and lipid synthetic genes and down-regulation of silence regulator gene 1, PGC-1α, adiponectin, and lipid degradation genes account for alcoholic hepatosteatosis. Induction of proinflammatory cytokines and depletion of endogenous antioxidant, glutathione, account for alcoholic steatohepatitis. We suggest betaine as a potential therapeutic agent because it effectively protects against adverse actions of ethanol.

Mouse spermatocytes express CYP2E1 and respond to acrylamide exposure

Metabolism of xenobiotics by cytochrome P450s (encoded by the CYP genes) often leads to bio-activation, producing reactive metabolites that interfere with cellular processes and cause DNA damage. In the testes, DNA damage induced by xenobiotics has been associated with impaired spermatogenesis and adverse effects on reproductive health. We previously reported that chronic exposure to the reproductive toxicant, acrylamide, produced high levels of DNA damage in spermatocytes of Swiss mice. CYP2E1 metabolises acrylamide to glycidamide, which, unlike acrylamide, readily forms adducts with DNA. Thus, to investigate the mechanisms of acrylamide toxicity in mouse male germ cells, we examined the expression of the CYP, CYP2E1, which metabolises acrylamide. Using Q-PCR and immunohistochemistry, we establish that CYP2E1 is expressed in germ cells, in particular in spermatocytes. Additionally, CYP2E1 gene expression was upregulated in these cells following in vitro acrylamide exposure (1 µM, 18 h). Spermatocytes were isolated and treated with 1 µM acrylamide or 0.5 µM glycidamide for 18 hours and the presence of DNA-adducts was investigated using the comet assay, modified to detect DNA-adducts. Both compounds produced significant levels of DNA damage in spermatocytes, with a greater response observed following glycidamide exposure. A modified comet assay indicated that direct adduction of DNA by glycidamide was a major source of DNA damage. Oxidative stress played a small role in eliciting this damage, as a relatively modest effect was found in a comet assay modified to detect oxidative adducts following glycidamide exposure, and glutathione levels remained unchanged following treatment with either compound. Our results indicate that the male germ line has the capacity to respond to xenobiotic exposure by inducing detoxifying enzymes, and the DNA damage elicited by acrylamide in male germ cells is likely due to the formation of glycidamide adducts.

Carvedilol improves ethanol-induced liver injury via modifying the interaction between oxidative stress and sympathetic hyperactivity in rats

AIM

Oxidative stress is a major pathway mediating ethanol hepatotoxicity and liver injury. We previously found that carvedilol, which can block the sympathetic nervous system via β1-, β2- and α1-adrenoreceptors, modifies ethanol-induced production of lipogenesis- and fibrogenesis-related mediators from hepatic stellate cells (HSC). In the present study, we assessed the effects of carvedilol on ethanol-induced liver injury, hepatic insulin resistance, and the interaction between oxidative stress and sympathetic hyperactivity in rats with alcoholic fatty liver disease (AFLD).

METHODS

Male Wistar rats were pair-fed for 49 days and divided into four groups: control and ethanol liquid-diet-fed rats with and without 7-day carvedilol treatment. Rats' sympathetic activity, hepatic oxidative stress, hepatic insulin resistance and liver injury were evaluated based on biochemical analysis, enzyme-linked immunosorbent assay, fluorescence immunohistochemistry, western blot and reverse transcriptase polymerase chain reaction.

RESULTS

Forty-nine days of ethanol consumption induced the increases in circulating noradrenaline metabolite (3-methoxy-4-hydroxyphenylglycol), hepatic noradrenaline and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, the downregulation of hepatic insulin receptor substrate-1 gene expression, and the accumulation of fatty droplets within hepatocytes with the increased hepatic triglyceride and blood alanine aminotransferase levels. All of these changes were modified by carvedilol treatment. 8-OHdG was detected in activated HSC and suppressed by carvedilol treatment based on fluorescence immunohistochemical double-staining analysis.

CONCLUSION

Carvedilol may modify the interaction between the oxidative stress and the sympathetic hyperactivity, and then contribute to attenuating the development of AFLD in rats. Additionally, oxidative stress may be responsible for the activation of HSC during the early stage of alcoholic liver disease.

Antialcoholic liver activity of whey fermented by Lactobacillus casei isolated from koumiss

Whey fermented liquid (WFL) was studied for its hepatoprotective effects by using chronic alcohol-induced mice. Whey fermented liquid, prepared by inoculating whey with 4% (vol/vol) Lactobacillus casei and then incubating at 41°C for 8h, was used to orally treat alcohol-induced mice at 3 dosages for 5 wk. Ethanol consumption significantly reduced the activity of superoxide dismutase and glutathione peroxidase, while lowering glutathione content and increasing levels of aspartate aminotransferase, alanine aminotransferase, total triglyceride, malondialdehyde, and cytochrome P450 2E1. Treatment with WFL significantly attenuated the increased levels of alanine aminotransferase, aspartate aminotransferase, triglyceride, and cytochrome P450 2E1, while decreasing superoxide dismutase, glutathione peroxidase, malondialdehyde, and glutathione levels. Pathological changes in the livers of mice who had ingested alcohol were improved by the administration of WFL. These results suggest that WFL may exert a protective effect against alcoholic liver disease by increasing antioxidant activity, which supports the use of WFL as an antialcoholic liver disease treatment.