A comparison of the effects of betaine and S-adenosylmethionine on ethanol-induced changes in methionine metabolism and steatosis in rat hepatocytes

Prenatal Choline Supplementation Improves Glucose Tolerance and Reduces Liver Fat Accumulation in Mouse Offspring Exposed to Ethanol during the Prenatal and Postnatal Periods

Prenatal alcohol exposure (AE) affects cognitive development. However, it is unclear whether prenatal AE influences the metabolic health of offspring and whether postnatal AE exacerbates metabolic deterioration resulting from prenatal AE. Choline is a semi-essential nutrient that has been demonstrated to mitigate the cognitive impairment of prenatal AE. This study investigated how maternal choline supplementation (CS) may modify the metabolic health of offspring with prenatal and postnatal AE (AE/AE). C57BL/6J female mice were fed either a Lieber-DeCarli diet with 1.4% ethanol between embryonic day (E) 9.5 and E17.5 or a control diet. Choline was supplemented with 4 × concentrations versus the control throughout pregnancy. At postnatal week 7, offspring mice were exposed to 1.4% ethanol for females and 3.9% ethanol for males for 4 weeks. AE/AE increased hepatic triglyceride accumulation in male offspring only, which was normalized by prenatal CS. Prenatal CS also improved glucose tolerance compared to AE/AE animals. AE/AE suppressed hepatic gene expression of peroxisome proliferator activated receptor alpha (Ppara) and low-density lipoprotein receptor (Ldlr), which regulate fatty acid catabolism and cholesterol reuptake, respectively, in male offspring. However, these changes were not rectified by prenatal CS. In conclusion, AE/AE led to an increased risk of steatosis and was partially prevented by prenatal CS in male mice.

Anti-inflammatory and antioxidant properties of betaine protect against sepsis-induced acute lung injury: CT and histological evidence

The aim of this research was to determine the anti-inflammatory effect of betaine on sepsis-induced acute respiratory distress syndrome (ARDS) in rats through histopathological examination, radiologic imaging, and biochemical analysis. Eight rats were included in the control group, and no procedure was performed. Feces intraperitoneal procedure (FIP) was performed on 24 rats to create a sepsis-induced ARDS model. These rats were separated into three groups as follows: FIP alone (sepsis group, n=8), FIP + saline (1 mL/kg, placebo group, n=8), and FIP + betaine (500 mg/kg, n=8). Computed tomography (CT) was performed after FIP, and the Hounsfield units (HU) value of the lungs was measured. The plasma levels of tumor necrosis factor (TNF)-α, interleukin-1β (IL-1β), IL-6, C-reactive protein, malondialdehyde (MDA), and lactic acid (LA) were determined, and arterial oxygen pressure (PaO2) and arterial CO2 pressure (PaCO2) were measured from an arterial blood sample. Histopathology was used to evaluate lung damage. This study completed all histopathological and biochemical evaluations in 3 months. All evaluated biomarkers were decreased in the FIP + betaine group compared to FIP + saline and FIP alone (all P<0.05). Also, the parenchymal density of the rat lung on CT and histopathological scores were increased in FIP + saline and FIP alone compared to control and these findings were reversed by betaine treatment (all P<0.05). Our study demonstrated that betaine suppressed the inflammation and ameliorated acute lung injury in a rat model of sepsis.

Advances in DNA, histone, and RNA methylation mechanisms in the pathophysiology of alcohol use disorder

Alcohol use disorder (AUD) has a complex, multifactorial etiology involving dysregulation across several brain regions and peripheral organs. Acute and chronic alcohol consumption cause epigenetic modifications in these systems, which underlie changes in gene expression and subsequently, the emergence of pathophysiological phenotypes associated with AUD. One such epigenetic mechanism is methylation, which can occur on DNA, histones, and RNA. Methylation relies on one carbon metabolism to generate methyl groups, which can then be transferred to acceptor substrates. While DNA methylation of particular genes generally represses transcription, methylation of histones and RNA can have bidirectional effects on gene expression. This review summarizes one carbon metabolism and the mechanisms behind methylation of DNA, histones, and RNA. We discuss the field's findings regarding alcohol's global and gene-specific effects on methylation in the brain and liver and the resulting phenotypes characteristic of AUD.

Implications of trimethylamine N-oxide (TMAO) and Betaine in Human Health: Beyond Being Osmoprotective Compounds

Osmolytes are naturally occurring small molecular weight organic molecules, which are accumulated in large amounts in all life forms to maintain the stability of cellular proteins and hence preserve their functions during adverse environmental conditions. Trimethylamine N-oxide (TMAO) and N,N,N-trimethylglycine (betaine) are methylamine osmolytes that have been extensively studied for their diverse roles in humans and have demonstrated opposing relations with human health. These osmolytes are obtained from food and synthesized endogenously using dietary constituents like choline and carnitine. Especially, gut microbiota plays a vital role in TMAO synthesis and contributes significantly to plasma TMAO levels. The elevated plasma TMAO has been reported to be correlated with the pathogenesis of numerous human diseases, including cardiovascular disease, heart failure, kidney diseases, metabolic syndrome, etc.; Hence, TMAO has been recognized as a novel biomarker for the detection/prediction of several human diseases. In contrast, betaine acts as a methyl donor in one-carbon metabolism, maintains cellular S-adenosylmethionine levels, and protects the cells from the harmful effects of increased plasma homocysteine. Betaine also demonstrates antioxidant and anti-inflammatory activities and has a promising therapeutic value in several human diseases, including homocystinuria and fatty liver disease. The present review examines the multifarious functions of TMAO and betaine with possible molecular mechanisms towards a better understanding of their emerging and diverging functions with probable implications in the prevention, diagnosis, and treatment of human diseases.

S-Adenosylmethionine: From the Discovery of Its Inhibition of Tumorigenesis to Its Use as a Therapeutic Agent

Alterations of methionine cycle in steatohepatitis, cirrhosis, and hepatocellular carcinoma induce MAT1A decrease and MAT2A increase expressions with the consequent decrease of S-adenosyl-L-methionine (SAM). This causes non-alcoholic fatty liver disease (NAFLD). SAM administration antagonizes pathological conditions, including galactosamine, acetaminophen, and ethanol intoxications, characterized by decreased intracellular SAM. Positive therapeutic effects of SAM/vitamin E or SAM/ursodeoxycholic acid in animal models with NAFLD and intrahepatic cholestasis were not confirmed in humans. In in vitro experiments, SAM and betaine potentiate PegIFN-alpha-2a/2b plus ribavirin antiviral effects. SAM plus betaine improves early viral kinetics and increases interferon-stimulated gene expression in patients with viral hepatitis non-responders to pegIFNα/ribavirin. SAM prevents hepatic cirrhosis, induced by CCl4, inhibits experimental tumors growth and is proapoptotic for hepatocellular carcinoma and MCF-7 breast cancer cells. SAM plus Decitabine arrest cancer growth and potentiate doxorubicin effects on breast, head, and neck cancers. Furthermore, SAM enhances the antitumor effect of gemcitabine against pancreatic cancer cells, inhibits growth of human prostate cancer PC-3, colorectal cancer, and osteosarcoma LM-7 and MG-63 cell lines; increases genomic stability of SW480 cells. SAM reduces colorectal cancer progression and inhibits the proliferation of preneoplastic rat liver cells in vivo. The discrepancy between positive results of SAM treatment of experimental tumors and modest effects against human disease may depend on more advanced human disease stage at moment of diagnosis.

Alcoholic liver disease: Current insights into cellular mechanisms

Alcoholic liver disease (ALD) due to chronic alcohol consumption is a significant global disease burden and a leading cause of mortality. Alcohol abuse induces a myriad of aberrant changes in hepatocytes at both the cellular and molecular level. Although the disease spectrum of ALD is widely recognized, the precise triggers for disease progression are still to be fully elucidated. Oxidative stress, mitochondrial dysfunction, gut dysbiosis and altered immune system response plays an important role in disease pathogenesis, triggering the activation of inflammatory pathways and apoptosis. Despite many recent clinical studies treatment options for ALD are limited, especially at the alcoholic hepatitis stage. We have therefore reviewed some of the key pathways involved in the pathogenesis of ALD and highlighted current trials for treating patients.

Beneficial Effects of Betaine: A Comprehensive Review

Medicinal herbs and many food ingredients possess favorable biological properties that contribute to their therapeutic activities. One such natural product is betaine, a stable, nontoxic natural substance that is present in animals, plants, and microorganisms. Betaine is also endogenously synthesized through the metabolism of choline or exogenously consumed through dietary intake. Betaine mainly functions as (i) an osmolyte and (ii) a methyl-group donor. This review describes the major physiological effects of betaine in whole-body health and its ability to protect against both liver- as well as non-liver-related diseases and conditions. Betaine's role in preventing/attenuating both alcohol-induced and metabolic-associated liver diseases has been well studied and is extensively reviewed here. Several studies show that betaine protects against the development of alcohol-induced hepatic steatosis, apoptosis, and accumulation of damaged proteins. Additionally, it can significantly prevent/attenuate progressive liver injury by preserving gut integrity and adipose function. The protective effects are primarily associated with the regulation of methionine metabolism through removing homocysteine and maintaining cellular SAM:SAH ratios. Similarly, betaine prevents metabolic-associated fatty liver disease and its progression. In addition, betaine has a neuroprotective role, preserves myocardial function, and prevents pancreatic steatosis. Betaine also attenuates oxidant stress, endoplasmic reticulum stress, inflammation, and cancer development. To conclude, betaine exerts significant therapeutic and biological effects that are potentially beneficial for alleviating a diverse number of human diseases and conditions.

Betaine increases mitochondrial content and improves hepatic lipid metabolism

The liver plays a critical role in lipid metabolism. Hepatic dysfunction is not only the direct cause of fatty liver disease, but the main risk factor for obesity, diabetes, and other metabolic diseases. So far, therapeutic strategies against fatty liver disease are very limited. Betaine is a methyl donor. Current studies reported that the intake of betaine decreases body fat and is beneficial for treatment of fatty liver disease and metabolic syndrome. However, the underlying mechanisms remain largely unknown. In this study, to investigate the role of betaine on hepatic lipid metabolism and explore the underlying mechanism, HepG2 cells were cultured with fatty acids and betaine. The data indicated that betaine inhibited hepatic fat accumulation and promoted mitochondrial content and activity, suggesting that betaine is involved in the regulation of lipid and energy metabolism. Gene expression analysis implied that betaine inhibits fatty acid synthesis, but stimulates fatty acid oxidation and lipid secretion. Further, to study the mechanism of betaine, FTO (RNA demethylase) and its mutant (loss of demethylase activity) were used. The results showed that FTO blocked the ability of betaine to regulate lipid metabolism and mitochondrial content, but the FTO mutant had no effect, suggesting that betaine influences RNA methylation. This work links betaine administration with mitochondrial activity and RNA methylation, and provides a potential target for the development of new therapeutic strategies for the treatment of fatty liver disease.

Alleviation of paraquat-induced oxidative lung injury by betaineviaregulation of sulfur-containing amino acid metabolism despite the lack of betaine-homocysteine methyltransferase (BHMT) in the lung

Betaine regulates sulfur-containing amino acid metabolism in the lung despite the lack of BHMT and increases pulmonary antioxidant capacity.

Whole-genome RNAi screen identifies methylation-related genes influencing lipid metabolism in Caenorhabditis elegans

Lipid droplets (LDs) are highly conserved multifunctional cellular organelles and aberrant lipid storage in LDs can lead to many metabolic diseases. However, the molecular mechanisms governing lipid dynamic changes remain elusive, and the high-throughput screen of genes influencing LD morphology was limited by lacking specific LD marker proteins in the powerful genetic tool Caenorhabditis elegans. In this study, we established a new method to conduct whole-genome RNAi screen using LD resident protein DHS-3 as a LD marker, and identified 78 genes involved in significant LD morphologic changes. Among them, mthf-1, as well as a series of methylation-related genes, was found dramatically influencing lipid metabolism. SREBP-1 and SCD1 homologs in C. elegans were involved in the lipid metabolic change of mthf-1(RNAi) worms, and the regulation of ATGL-1 also contributed to it by decreasing triacylglycerol (TAG) hydrolysis. Overall, this study not only identified important genes involved in LD dynamics, but also provided a new tool for LD study using C. elegans, with implications for the study of lipid metabolic diseases.

Role of Nutrition in Alcoholic Liver Disease: Summary of the Symposium at the ESBRA 2017 Congress

The symposium, “Role of Nutrition in Alcoholic Liver Disease”, was held at the European Society for Biomedical Research on Alcoholism Congress on 9 October 2017 in Crete, Greece. The goal of the symposium was to highlight recent advances and developments in the field of alcohol and nutrition. The symposium was focused on experimental and clinical aspects in relation to the role of different types of dietary nutrients and malnutrition in the pathogenesis of alcoholic liver disease (ALD). The following is a summary of key research presented at this session. The speakers discussed the role of dietary fats and carbohydrates in the development and progression of alcohol-induced multi-organ pathology in animal models of ALD, analyzed novel nutrition-related therapeutics (specifically, betaine and zinc) in the treatment of ALD, and addressed clinical relevance of malnutrition and nutrition support in ALD. This summary of the symposium will benefit junior and senior faculty currently investigating alcohol-induced organ pathology as well as undergraduate, graduate, and post-graduate students and fellows.

Supplement of Betaine into Embryo Culture Medium Can Rescue Injury Effect of Ethanol on Mouse Embryo Development

Mammal embryos can be impaired by mother’s excessive ethanol uptake, which induces a higher level of reactive oxygen species (ROS) and interferes in one carbon unit metabolism. Here, our analysis by in vitro culture system reveals immediate effect of ethanol in medium on mouse embryo development presents concentration dependent. A preimplantation embryo culture using medium contained 1% ethanol could impact greatly early embryos development, and harmful effect of ethanol on preimplantation embryos would last during the whole development period including of reducing ratio of blastocyst formation and implantation, and deteriorating postimplantation development. Supplement of 50 μg/ml betaine into culture medium can effectively reduce the level of ROS caused by ethanol in embryo cells and rescue embryo development at each stage damaged by ethanol, but supplement of glycine can’t rescue embryo development as does betaine. Results of 5-methylcytosine immunodetection indicate that supplement of betaine into medium can reduce the rising global level of genome DNA methylation in blastocyst cells caused by 1% ethanol, but glycine can’t play the same impact. The current findings demonstrate that betaine can effectively rescue development of embryos harmed by ethanol, and possibly by restoring global level of genome DNA methylation in blastocysts.

Effects of S-Adenosylmethionine and Its Combinations With Taurine and/or Betaine on Glutathione Homeostasis in Ethanol-induced Acute Hepatotoxicity

Background

Exposure to ethanol abuse and severe oxidative stress are risk factors for hepatocarcinoma. The aim of this study was to evaluate the effects of S-adenosylmethionine (SAMe) and its combinations with taurine and/or betaine on the level of glutathione (GSH), a powerful antioxidant in the liver, in acute hepatotoxicity induced by ethanol.

Methods

To examine the effects of SAMe and its combinations with taurine and/or betaine on ethanol-induced hepatotoxicity, AML12 cells and C57BL/6 mice were pretreated with SAMe, taurine, and/or betaine, followed by ethanol challenge. Cell viability was detected with an MTT assay. GSH concentration and mRNA levels of GSH synthetic enzymes were measured using GSH reductase and quantitative real-time reverse transcriptase-PCR. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were measured with commercially available kits.

Results

Pretreatment of SAMe, with or without taurine and/or betaine, attenuated decreases in GSH levels and mRNA expression of the catalytic subunit of glutamate-cysteine ligase (GCL), the rate-limiting enzyme for GSH synthesis, in ethanol-treated cells and mice. mRNA levels of the modifier subunit of GCL and glutathione synthetase were increased in mice treated with SAMe combinations. SAMe, taurine, and/or betaine pretreatment restored serum ALT and AST levels to control levels in the ethanol-treated group.

Conclusions

Combinations of SAMe with taurine and/or betaine have a hepatoprotective effect against ethanol-induced liver injury by maintaining GSH homeostasis.

Betaine Attenuates Alcohol-Induced Pancreatic Steatosis

OBJECTIVES

To explore the effect of betaine on alcoholic pancreatic steatosis and its mechanism.

METHODS

Rats were randomly assigned to control, ethanol, or ethanol + betaine groups. Changes in pancreatic morphology; serum lipid levels; and pancreatic lipid, amylase and lipase levels were determined. The serum and adipose tissue adiponectin level was measured by an enzyme-linked immunoassay. Adiponectin receptor-1 (AdipoR1), AdipoR2, sterol regulatory element binding protein-1c (SREBP-1c), SREBP-2, and fatty acid synthetase expression levels were quantified. The SREBP-1c expression in SW1990 cells treated with various concentrations of ethanol or ethanol plus betaine and/or adiponectin was assessed.

RESULTS

Alcohol-induced changes in pancreatic morphology were attenuated by betaine. Pancreatic triglyceride, free fatty acid and expression levels of SREBP-1c and fatty acid synthetase were elevated after ethanol feeding but remained at control levels after betaine supplementation. Alcohol-induced decreases in serum and adipose tissue adiponectin, pancreatic AdipoR1, amylase, and lipase were attenuated by betaine. Serum triglyceride and free fatty acid levels were elevated after alcohol consumption and remained higher after betaine supplementation compared with controls. Betaine and/or adiponectin suppressed alcohol-induced SREBP-1c upregulation in vitro.

CONCLUSIONS

Betaine attenuated alcoholic-induced pancreatic steatosis most likely by suppressing pancreatic SREBP-1c both directly and through the restoration of adiponectin signaling.

Acute alcohol exposure during mouse gastrulation alters lipid metabolism in placental and heart development: Folate prevention

Background

Embryonic acute exposure to ethanol (EtOH), lithium, and homocysteine (HCy) induces cardiac defects at the time of exposure; folic acid (FA) supplementation protects normal cardiogenesis (Han et al., 2009, 2012; Serrano et al., 2010). Our hypothesis is that EtOH exposure and FA protection relate to lipid and FA metabolism during mouse cardiogenesis and placentation.

Methods

On the morning of conception, pregnant C57BL/6J mice were placed on either of two FA‐containing diets: a 3.3 mg health maintenance diet or a high FA diet of 10.5 mg/kg. Mice were injected a binge level of EtOH, HCy, or saline on embryonic day (E) 6.75, targeting gastrulation. On E15.5, cardiac and umbilical blood flow were examined by ultrasound. Embryonic cardiac tissues were processed for gene expression of lipid and FA metabolism; the placenta and heart tissues for neutral lipid droplets, or for medium chain acyl‐dehydrogenase (MCAD) protein.

Results

EtOH exposure altered lipid‐related gene expression on E7.5 in comparison to control or FA‐supplemented groups and remained altered on E15.5 similarly to changes with HCy, signifying FA deficiency. In comparison to control tissues, the lipid‐related acyl CoA dehydrogenase medium length chain gene and its protein MCAD were altered with EtOH exposure, as were neutral lipid droplet localization in the heart and placenta.

Conclusion

EtOH altered gene expression associated with lipid and folate metabolism, as well as neutral lipids, in the E15.5 abnormally functioning heart and placenta. In comparison to controls, the high FA diet protected the embryo and placenta from these effects allowing normal development. Birth Defects Research (Part A) 106:749–760, 2016. © 2016 The Authors Birth Defects Research Part A: Clinical and Molecular Teratology Published by Wiley Periodicals, Inc.

White matter changes in chronic alcoholic liver disease: Hypothesized association and putative biochemical mechanisms

Advanced liver disease has long been associated with cerebral abnormalities. These abnormalities, termed acquired hepatocerebral degeneration, are typically visualized as T1 weighted hyperintensity on MRI in the deep gray matter of the basal ganglia. Recent reports, however, have demonstrated that a subset of patients with chronic alcoholic liver disease may also develop white matter abnormalities. Thus far, the morphology of these changes is not well characterized. Previous studies have described these changes as patchy, sporadic white matter abnormalities but have not posited localization of these changes to any particular white matter tracts. This paper hypothesizes that the white matter findings associated with advanced alcoholic liver disease localize to the corticocerebellar tracts. As an initial investigation of this hypothesis, 78 patients with a diagnosis of liver cirrhosis and an MRI showing clearly abnormal T1 weighted hyperintensity in the bilateral globus pallidus, characteristic of chronic liver disease, were examined for white matter signal abnormalities in the corticocerebellar tracts using FLAIR and T2 weighted images. The corticocerebellar tracts were subdivided into two regions: periventricular white matter (consisting of the sum of the centrum-semiovale and corona radiata), and lower white matter (consisting of the corona radiata, internal capsules, middle cerebral peduncles, middle cerebellar peduncles and cerebellum). As compared to matched controls, significantly greater signal abnormalities in both the periventricular white matter and lower white matter regions of the corticocerebellar tracts were observed in patients with known liver cirrhosis and abnormal T1 W hyperintensity in the globi pallidi. This difference was most pronounced in the lower white matter region of the corticocerebellar tract, with statistical significance of p<0.0005. Furthermore, the pathophysiologic mechanism underlying these changes remains unknown. This paper hypothesizes that the etiology of white matter changes associated with advanced liver disease may resemble that of white matter findings in subacute combined degeneration secondary to vitamin B12 deficiency. Specifically, significant evidence suggests that dysfunctional methionine metabolism as well as dysregulated cytokine production secondary to B12 deficiency play a major role in the development of subacute combined degeneration. Similar dysfunction of methionine metabolism and cytokine regulation is seen in alcoholic liver disease and is hypothesized in this paper to, at least in part, lead to white matter findings associated with alcoholic liver disease.

Epigenetic mechanisms are involved in the regulation of ethanol consumption in mice

BACKGROUND

Repeated alcohol exposure is known to increase subsequent ethanol consumption in mice. However, the underlying mechanisms have not been fully elucidated. One postulated mechanism involves epigenetic modifications, including histone modifications and DNA methylation of relevant genes such as NR2B or BDNF.

METHODS

To investigate the role of epigenetic mechanisms in the development of alcohol drinking behavior, an established chronic intermittent ethanol exposure reinforced ethanol drinking mouse model with vapor inhalation over two 9-day treatment regimens was used. The DNA methyltransferase inhibitor, 5-azacytidine or the histone deacetylase inhibitor, Trichostatin A was administered (intraperitoneally) to C57BL/6 mice 30 min before daily exposure to chronic intermittent ethanol. Changes in ethanol consumption were measured using the 2-bottle choice test.

RESULTS

The results indicated that systemic administration of Trichostatin A (2.5 µg/g) facilitated chronic intermittent ethanol-induced ethanol drinking, but systemic administration of 5-azacytidine (2 µg/g) did not cause the same effect. However, when 5-azacytidine was administered by intracerebroventricular injection, it facilitated chronic intermittent ethanol-induced ethanol drinking. Furthermore, the increased drinking caused by chronic intermittent ethanol was prevented by injection of a methyl donor, S-adenosyl-L-methionine. To provide evidence that chronic intermittent ethanol- or Trichostatin A-induced DNA demethylation and histone modifications of the NR2B promoter may underlie the altered ethanol consumption, we examined epigenetic modifications and NR2B expression in the prefrontal cortex of these mice. Chronic intermittent ethanol or Trichostatin A decreased DNA methylation and increased histone acetylation in the NR2B gene promoter, as well as mRNA levels of NR2B in these mice.

CONCLUSIONS

Taken together, these results indicate that epigenetic modifications are involved in regulating ethanol drinking behavior, partially through altering NR2B expression.

Role of betaine in improving the antidepressant effect of S-adenosyl-methionine in patients with mild-to-moderate depression

Background

S-adenosyl-methionine (SAMe) is a common add-on treatment used to counteract depressive symptoms in subjects with mild-to-moderate depression, who are low responders to other antidepressant drugs. However, there is some concern about the possible impact of SAMe therapy on homocysteine levels. Betaine is known both to counteract high level of homocysteine in plasma and to increase liquor and plasma levels of SAMe, thus potentiating its effect.

Aim

To evaluate the role played by betaine, administered along with SAMe, in potentiating the antidepressive role played by SAMe administered as such.

Methods

The study enrolled 46 subjects with a diagnosis of mild-to-moderate depression according to the Beck Depression Inventory Scale II. All the subjects had a suboptimal control of their symptoms. After randomization, they were treated with adjunctive treatment with either Samyr^® (enteric-coated SAMe) or DDM Metile^® (enteric-coated SAMe plus betaine) for 90 days.

Results

Both treatments acted similarly in improving symptoms such as anxiety, psychomotor agitation, feelings of helplessness and worthlessness, physical efficiency, and somatization, but treatment with DDM Metile^® determined better statistically significant results following a 90-day therapy. Tolerability and compliance were overlapping in both the treatments.

Conclusion

The association of SAMe plus betaine seemed to demonstrate more effectiveness than SAMe alone when administered as an add-on therapy to subjects, affected by mild-to-moderate depression, who were low responders to conventional antidepressants.

(1)H NMR-based metabolomics study on a goldfish model of Parkinson's disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)

A goldfish (Carassius auratus) model of Parkinson's disease (PD) was constructed by a single dose of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) according to previously reported methods. Global metabolite changes in brain of the MPTP induced goldfish model of PD were investigated. (1)H NMR-based metabolomics combined with various statistical methods such as orthogonal partial least squares discriminant analysis (OPLS-DA) and two-dimensional statistical total correlation spectroscopy (2D-STOCSY) found significant increase of leucine, isoleucine, valine, alanine, alanylalanine, creatinine, myo-inositol, 18:2 fatty acid, total fatty acids, arachic alcohol, taurine and significant decrease of N-acetylaspartate, (phospho)creatine, (phospho)choline, betaine, glutamine, 3-hexenedioate, acetamide, malonate, isocitrate, scyllo-inositol, phosphatidylcholines, cholesterols, n-3 fatty acids, polyunsaturated fatty acids (PUFAs) in brain of MPTP induced PD goldfish. These disturbed metabolite levels were involved in oxidative stress, energy failure, neuronal cell injury and death, consistent with those observed in clinical PD patients, and rodents and primates model of PD, indicating that the acute MPTP model of goldfish was an ideal and valuable model for PD research. In addition, several unusual metabolites in brain were significantly changed between MPTP induced PD and control goldfish, which might also play an important role in the pathogenesis of PD. This study also demonstrated the applicability and potential of (1)H NMR-based metabolomics approach for evaluation of animal models of disease induced by chemicals, such as MPTP-induced PD goldfish.

Ethanol affects hepatitis C pathogenesis: humanized SCID Alb-uPA mouse model

Alcohol consumption exacerbates the course of hepatitis C viral (HCV) infection, worsens outcomes and contributes to the development of chronic infection that exhibits low anti-viral treatment efficiency. The lack of suitable in vivo models makes HCV-ethanol studies very difficult. Here, we examine whether chimeric SCID Alb-uPA mice transplanted with human hepatocytes and infected with HCV develop worsening pathology when fed ethanol. After 5 weeks of feeding, such mice fed chow+water (control) or chow+20% ethanol in water (EtOH) diets mice developed oxidative stress, decreased proteasome activity and increased steatosis. Importantly, HCV(+) mice in the control group cleared HCV RNA after 5 weeks, while the infection persisted in EtOH-fed mice at the same or even higher levels compared with pre-feeding HCV RNA. We conclude that in chimeric SCID Alb-uPA mice, EtOH exposure causes the complex biochemical and histological changes typical for alcoholic liver injury. In addition, ethanol feeding delays the clearance of HCV RNA thereby generating persistent infection and promoting liver injury. Overall, this model is appropriate for conducting HCV-ethanol studies.

S-Adenosylmethionine (SAM)-Accumulating Sake Yeast Suppresses Acute Alcohol-Induced Liver Injury in Mice

The suppressive effects on acute alcoholic liver injury of S-adenosylmethionine (SAM) and the sake yeast, Saccharomyces cerevisiae Kyokai No. 9, have been shown previously. To enhance the suppression of acute alcoholic liver injury by sake yeast, we prepared SAM-accumulating sake yeast (SAM yeast). Male C57BL/6 mice that had been fed on a diet containing 0.25% SAM yeast or sake yeast for two weeks received three doses of ethanol (5 g/kg BW). In the mice fed on the SAM yeast, the ethanol-induced increases in both triglyceride (TG) and alanine aminotransferase (ALT) were significantly repressed. In addition, the SAM yeast-fed mice did not show an ethanol-induced decrease in hepatic SAM level, suggesting that a disorder of methionine metabolism in the liver caused by ethanol was relieved by the SAM yeast. These results suggest that the SAM yeast had a stronger effect suppressing acute alcoholic liver injury in mice than the sake yeast.

CYP2E1, oxidative stress, post-translational modifications and lipid metabolism

Chronic alcohol-mediated down-regulation of hepatic ST6Gal1 gene leads to defective glycosylation of lipid-carrying apolipoproteins such as apo E and apo J, resulting in defective VLDL assembly and intracellular lipid and lipoprotein transport, which in turn is responsible for alcoholic hepatosteatosis and ALD. The mechanism of ethanol action involves thedepletion of a unique RNA binding protein that specifically interacts with its 3'-UTR region of ST6Gal1 mRNA resulting in its destabilization and consequent appearance of asialoconjugates as alcohol biomarkers. With respect to ETOH effects on Cardio-Vascular Diseases, we conclude that CYP2E1 and ETOH mediated oxidative stress significantly down regulates not only the hepatic PON1 gene expression, but also serum PON1 and HCTLase activities accompanied by depletion of hepatic GSH, the endogenous antioxidant. These results strongly implicate the susceptibility of PON1 to increased ROS production. In contrast, betaine seems to be both hepatoprotective and atheroprotective by reducing hepatosteatosis and restoring not only liver GSH that quenches free radicals, but also the antiatherogenic PON1 gene expression and activity.

Ethanol and hepatitis C virus suppress peptide-MHC class I presentation in hepatocytes by altering proteasome function

BACKGROUND

Previously, we reported that exposure of hepatitis C virus (HCV) core-expressing ethanol (EtOH)-metabolizing cells to EtOH significantly suppresses proteasome activity which exists as 26S (20S and 19S) and as an unassociated 20S particle. The replacement of the constitutive proteasomal subunits with immunoproteasome (IPR) favors antigen processing. Here, we examined the effects of EtOH consumption by HCV core transgenic mice on proteasome activity in hepatocytic lysates and in partially purified 26S proteasome and the impact of these changes on antigen presentation.

METHODS

HCV (-) and HCV (+) core transgenic mice were fed chow diet with or without 20% (v/v) EtOH in water for 4 weeks. Following the feeding regimen, hepatocytes were isolated and examined for chymotrypsin-like proteasome activity, oxidative stress, and the presentation of SIINFEKL-H2Kb complex. Additionally, the constitutive proteasome and IPR were purified for further analysis and identification of proteasome-interacting proteins (PIPs).

RESULTS

EtOH significantly decreased proteasome activity in hepatocytes of HCV (+) mice, and this finding correlated with oxidative stress and dysregulated methylation reactions. In isolated 26S proteasome, EtOH suppressed proteasome activity equally in HCV (+) and HCV (-) mice. EtOH feeding caused proteasome instability and lowered the content of both constitutive and IPR subunits in the 20S proteasome. In addition, the level of other PIPs, PA28 and UCHL5, were also suppressed after EtOH exposure. Furthermore, in EtOH-fed mice and, especially, in HCV (+) mice, the presentation of SIINFEKL-H2Kb complex in hepatocytes was also decreased.

CONCLUSIONS

Proteasomal dysfunction induced by EtOH feeding and exacerbated by the presence of HCV structural proteins led to suppression of SIINFEKL-H2Kb presentation in hepatocytes.

4-Hydroxynonenal differentially regulates adiponectin gene expression and secretion via activating PPARγ and accelerating ubiquitin-proteasome degradation

Although well-established, the underlying mechanisms involved in obesity-related plasma adiponectin decline remain elusive. Oxidative stress is associated with obesity and insulin resistance and considered to contribute to the progression toward obesity-related metabolic disorders. In this study, we investigated the effects of 4-hydroxynonenal (4-HNE), the most abundant lipid peroxidation end product, on adiponectin production and its potential implication in obesity-related adiponectin decrease. Long-term high-fat diet feeding led to obesity in mouse, accompanied by decreased plasma adiponectin and increased adipose tissue 4-HNE content. Exposure of adipocytes to exogenous 4-HNE resulted in decreased adiponectin secretion in a dose-dependent manner, which was consistent with significantly decreased intracellular adiponectin protein abundance. In contrast, adiponectin gene expression was significantly elevated by 4-HNE treatment, which was concomitant with increased peroxisome proliferator-activated receptor gamma (PPAR-γ) gene expression and transactivity. The effect was abolished by T0070907, a PPAR-γ antagonist, suggesting that PPAR-γ activation plays a critical role in this process. To gain insight into mechanisms involved in adiponectin protein decrease, we examined the effects of 4-HNE on adiponectin protein degradation. Cycloheximide (CHX)-chase assay revealed that 4-HNE exposure accelerated adiponectin protein degradation, which was prevented by MG132, a potent proteasome inhibitor. Immunoprecipitation assay showed that 4-HNE exposure increased ubiquitinated adiponectin protein levels. These data altogether indicated that 4-HNE enhanced adiponectin protein degradation via ubiquitin-proteasome system. Finally, we demonstrated that supplementation of HF diet with betaine, an antioxidant and methyl donor, alleviated high-fat-induced adipose tissue 4-HNE increase and attenuated plasma adiponectin decline. Taken together, our findings suggest that the lipid peroxidation product 4-HNE can differentially regulates adiponectin gene expression and protein abundance and may play a mechanistic role in obesity-related plasma adiponectin decline.

Aberrant hepatic methionine metabolism and gene methylation in the pathogenesis and treatment of alcoholic steatohepatitis

The pathogenesis of alcoholic steatohepatitis (ASH) involves ethanol-induced aberrations in hepatic methionine metabolism that decrease levels of S-adenosylmethionine (SAM), a compound which regulates the synthesis of the antioxidant glutathione and is the principal methyl donor in the epigenetic regulation of genes relevant to liver injury. The present paper describes the effects of ethanol on the hepatic methionine cycle, followed by evidence for the central role of reduced SAM in the pathogenesis of ASH according to clinical data and experiments in ethanol-fed animals and in cell models. The efficacy of supplemental SAM in the prevention of ASH in animal models and in the clinical treatment of ASH will be discussed.

Betaine treatment attenuates chronic ethanol-induced hepatic steatosis and alterations to the mitochondrial respiratory chain proteome

Introduction. Mitochondrial damage and disruption in oxidative phosphorylation contributes to the pathogenesis of alcoholic liver injury. Herein, we tested the hypothesis that the hepatoprotective actions of betaine against alcoholic liver injury occur at the level of the mitochondrial proteome. Methods. Male Wister rats were pair-fed control or ethanol-containing liquid diets supplemented with or without betaine (10 mg/mL) for 4-5 wks. Liver was examined for triglyceride accumulation, levels of methionine cycle metabolites, and alterations in mitochondrial proteins. Results. Chronic ethanol ingestion resulted in triglyceride accumulation which was attenuated in the ethanol plus betaine group. Blue native gel electrophoresis (BN-PAGE) revealed significant decreases in the content of the intact oxidative phosphorylation complexes in mitochondria from ethanol-fed animals. The alcohol-dependent loss in many of the low molecular weight oxidative phosphorylation proteins was prevented by betaine supplementation. This protection by betaine was associated with normalization of SAM : S-adenosylhomocysteine (SAH) ratios and the attenuation of the ethanol-induced increase in inducible nitric oxide synthase and nitric oxide generation in the liver. Discussion/Conclusion. In summary, betaine attenuates alcoholic steatosis and alterations to the oxidative phosphorylation system. Therefore, preservation of mitochondrial function may be another key molecular mechanism responsible for betaine hepatoprotection.

Mechanisms of alcohol-induced endoplasmic reticulum stress and organ injuries

Alcohol is readily distributed throughout the body in the blood stream and crosses biological membranes, which affect virtually all biological processes inside the cell. Excessive alcohol consumption induces numerous pathological stress responses, part of which is endoplasmic reticulum (ER) stress response. ER stress, a condition under which unfolded/misfolded protein accumulates in the ER, contributes to alcoholic disorders of major organs such as liver, pancreas, heart, and brain. Potential mechanisms that trigger the alcoholic ER stress response are directly or indirectly related to alcohol metabolism, which includes toxic acetaldehyde and homocysteine, oxidative stress, perturbations of calcium or iron homeostasis, alterations of S-adenosylmethionine to S-adenosylhomocysteine ratio, and abnormal epigenetic modifications. Interruption of the ER stress triggers is anticipated to have therapeutic benefits for alcoholic disorders.

Vitamin-dependent methionine metabolism and alcoholic liver disease

Emerging evidence indicates that ethanol-induced alterations in hepatic methionine metabolism play a central role in the pathogenesis of alcoholic liver disease (ALD). Because malnutrition is a universal clinical finding in this disease and hepatic methionine metabolism is dependent upon dietary folate and vitamins B-6 and B-12, ALD can be considered an induced nutritional disorder that is conditioned by alcohol abuse. The present review describes the etiologies of these 3 vitamin deficiencies in ALD and how they interact with chronic ethanol exposure to alter hepatic methionine metabolism. Subsequent sections focus on molecular mechanisms for the interactions of aberrant methionine metabolism with ethanol in the pathogenesis of ALD, in particular the role of S-adenosylmethionine (SAM) in regulating the epigenetic expressions of genes relevant to pathways of liver injury. The review will conclude with descriptions of studies on the efficacy of SAM in the treatment of ALD and with discussion of potentially fruitful future avenues of research.

Histone modifications and alcohol-induced liver disease: Are altered nutrients the missing link?

Alcoholism is a major health problem in the United States and worldwide, and alcohol remains the single most significant cause of liver-related diseases and deaths. Alcohol is known to influence nutritional status at many levels including nutrient intake, absorption, utilization, and excretion, and can lead to many nutritional disturbances and deficiencies. Nutrients can dramatically affect gene expression and alcohol-induced nutrient imbalance may be a major contributor to pathogenic gene expression in alcohol-induced liver disease (ALD). There is growing interest regarding epigenetic changes, including histone modifications that regulate gene expression during disease pathogenesis. Notably, modifications of core histones in the nucleosome regulate chromatin structure and DNA methylation, and control gene transcription. This review highlights the role of nutrient disturbances brought about during alcohol metabolism and their impact on epigenetic histone modifications that may contribute to ALD. The review is focused on four critical metabolites, namely, acetate, S-adenosylmethionine, nicotinamide adenine dinucleotide and zinc that are particularly relevant to alcohol metabolism and ALD.

Protective effect of quercetin, EGCG, catechin and betaine against oxidative stress induced by ethanol in vitro

There is a need for a nontoxic antioxidant agent to be identified which will prevent alcoholic liver disease (ALD) in alcoholic patients. We tested 4 candidate agents: quercetin, EGCG, catechin and betaine, all of which occur naturally in food. HepG2 cells overexpressing CYP2E1 were subjected to arachidonic acid, iron and 100mM ethanol with or without the antioxidant agent. All the agents prevented oxidative stress and MDA/4HNE formation induced by ethanol, except for EGCG. Catechin prevented CYP2E1 induction by ethanol. All the agents tended to down-regulate the ethanol-induced increased expression of glutathionine peroxidase 4 (GPX4). All the agents, except catechin, tended to reduce the expression of SOD2 induced by ethanol. Heat shock protein 70 was up-regulated by ethanol alone and betaine tended to prevent this. All 4 agents down-regulated the expression of Gadd45b in the presence of ethanol, which could explain the mechanism of DNA demethylation associated with the up-regulation of the gene expression observed in experimental ALD. In conclusion, the in vitro model of oxidative stress induced by ethanol provided evidence that all 4 agents tested prevented some aspect of liver cell injury caused by ethanol.

Ethanol lowers glutathione in rat liver and brain and inhibits methionine synthase in a cobalamin-dependent manner

BACKGROUND

Methionine synthase (MS) is a ubiquitous enzyme that requires vitamin B12 (cobalamin) and 5-methyl-tetrahydrofolate for the methylation of homocysteine to methionine. Previous studies have shown that acute or chronic ethanol (ETOH) administration results in the inhibition of MS and depletion of glutathione (GSH), and it has been proposed that GSH is required for the synthesis of methylcobalamin (MeCbl).

METHODS

We measured GSH levels and investigated the ability of different cobalamin cofactors [cyano- (CNCbl), glutathionyl- (GSCbl), hydroxo- (OHCbl), and MeCbl] to support MS activity in liver and brain cortex from control and ETOH-treated rats.

RESULTS

In control animals, MS activity was higher in liver than in cortex for all cobalamins and MeCbl-based activity was higher than for other cofactors. S-adenosylmethionine (SAM) was required for OHCbl, CNCbl, and GSCbl-based activity, but not for MeCbl. Feeding an ETOH-containing diet for four weeks caused a significant decrease in liver MS activity, in a cobalamin-dependent manner (OHCbl ≥ CNCbl > GSCbl > MeCbl). In brain cortex, OHCbl, CNCbl, and GSCbl-based activity was reduced by ETOH treatment, but MeCbl-based activity was unaffected. GSH levels were reduced by ETOH treatment in both liver and cortex homogenates, and addition of GSH restored OHCbl-based MS activity to control levels. Betaine administration had no significant effect on GSH levels or MS activity in either control or ETOH-fed groups.

CONCLUSIONS

The ETOH-induced decrease in OHCbl-based MS activity is secondary to decreased GSH levels and a decreased ability to synthesize MeCbl. The ability of MeCbl to completely offset ETOH inhibition in brain cortex, but not liver, suggests tissue-specific differences in the GSH-dependent regulation of MS activity.

Analysis of the liver mitochondrial proteome in response to ethanol and S-adenosylmethionine treatments: novel molecular targets of disease and hepatoprotection

S-adenosylmethionine (SAM) minimizes alcohol hepatotoxicity; however, the molecular mechanisms responsible for SAM hepatoprotection remain unknown. Herein, we use proteomics to determine whether the hepatoprotective action of SAM against early-stage alcoholic liver disease is linked to alterations in the mitochondrial proteome. For this, male rats were fed control or ethanol-containing liquid diets +/- SAM and liver mitochondria were prepared for proteomic analysis. Two-dimensional isoelectric focusing (2D IEF/SDS-PAGE) and blue native gel electrophoresis (BN-PAGE) were used to determine changes in matrix and oxidative phosphorylation (OxPhos) proteins, respectively. SAM coadministration minimized alcohol-dependent inflammation and preserved mitochondrial respiration. SAM supplementation preserved liver SAM levels in ethanol-fed rats; however, mitochondrial SAM levels were increased by ethanol and SAM treatments. With use of 2D IEF/SDS-PAGE, 30 proteins showed significant changes in abundance in response to ethanol, SAM, or both. Classes of proteins affected by ethanol and SAM treatments were chaperones, beta oxidation proteins, sulfur metabolism proteins, and dehydrogenase enzymes involved in methionine, glycine, and choline metabolism. BN-PAGE revealed novel changes in the levels of 19 OxPhos proteins in response to ethanol, SAM, or both. Ethanol- and SAM-dependent alterations in the proteome were not linked to corresponding changes in gene expression. In conclusion, ethanol and SAM treatment led to multiple changes in the liver mitochondrial proteome. The protective effects of SAM against alcohol toxicity are mediated, in part, through maintenance of proteins involved in key mitochondrial energy conserving and biosynthetic pathways. This study demonstrates that SAM may be a promising candidate for treatment of alcoholic liver disease.

Hepatoprotective effects of S-adenosyl-L-methionine against alcohol- and cytochrome P450 2E1-induced liver injury

S-adenosyl-L-methionine (SAM) acts as a methyl donor for methylation reactions and participates in the synthesis of glutathione. SAM is also a key metabolite that regulates hepatocyte growth, differentiation and death. Hepatic SAM levels are decreased in animal models of alcohol liver injury and in patients with alcohol liver disease or viral cirrhosis. This review describes the protection by SAM against alcohol and cytochrome P450 2E1-dependent cytotoxicity both in vitro and in vivo and evaluates mechanisms for this protection.

The effects of betaine treatment on rats fed an acute bolus of ethanol at 3 and 12 h post bolus: a microarray analysis

Betaine, a methyl donor active in methionine metabolism, is effective in preventing and reversing experimental alcohol liver disease. The metabolic and molecular biologic mechanisms involved in this prevention are only partially known. To further investigate how betaine modifies the effects of ethanol on the liver, rats were given an acute ethanol bolus with or without betaine and the results were compared to isocaloric dextrose-fed controls. Livers were subjected to microarray analysis, and functional pathways and individual gene expression changes were analyzed. Experimental groups were compared by Venn diagrams showing that both ethanol and betaine caused a change in the expression of a large number of genes indicating that the changes were global. The bio-informatic analysis showed that all the KEGG functional pathways were affected and mainly down regulated at 3 h post bolus when ethanol plus betaine were compared with ethanol-fed rats. The most profound effect of betaine was on the metabolic pathways both at 3 and 12 h post bolus. At 3 h, the changes in gene expression were mostly down regulated, but at 12 h, the changes were regulated equally up and down. This hypothesis-driven analysis showed that the effects of betaine on the effects of ethanol were partly transient.

Betaine inhibits Toll-like receptor 4 expression in rats with ethanol-induced liver injury

AIM: To test whether ethanol feeding could induce Toll-like receptor 4 (TLR4) responses, assess the hepatoprotective effect of betaine and its inhibitive effect on TLR4 in animal models of alcoholic liver injury.

METHODS: Forty-eight female Sprague-Dawley rats were randomly divided into four groups as control, model, low and high dose betaine groups. Except control group, all rats were fed with high fat-containing diet plus ethanol and fish oil gavages for 8 wk. Betaine was administered intragastrically after exposure of ethanol for 4 wk. The changes of liver histology were examined. The expression of TLR4 mRNA and protein was detected by RT-PCR and Western blotting, respectively. The serum aminotransferase activity [alanine transarninase (ALT), aspartate aminotransferase (AST)], serum endotoxin, and liver inflammatory factors [tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-18 (IL-18)] were also assayed.

RESULTS: Compared with control group, rats of model group developed marked liver injury, accompanied by an increase of ALT (159.41 ± 7.74 U/L vs 59.47 ± 2.34 U/L, P < 0.0001), AST (248.25 ± 1.40 U/L vs 116.89 ± 3.48 U/L, P < 0.0001), endotoxin (135.37 ± 30.17 ng/L vs 44.15 ± 7.54 ng/L, P < 0.0001), TNF-α (20.81 ± 8.58 pg/mL vs 9.34 ± 2.57 pg/mL, P = 0.0003), IFN-γ (30.18 ± 7.60 pg/mL vs 16.86 ± 9.49 pg/mL, P = 0.0039) and IL-18 (40.99 ± 8.25 pg/mL vs 19.73 ± 9.31 pg/mL, P = 0.0001). At the same time, the expression of TLR4 mRNA and protein was markedly induced in the liver after chronic ethanol consumption (1.45 ± 0.07 vs 0.44 ± 0.04, P < 0.0001; 1.83 ± 0.13 vs 0.56 ± 0.08, P < 0.0001). Compared with model group, betaine feeding resulted in significant decreases of ALT (64.93 ± 6.06 U/L vs 159.41 ± 7.74 U/L, P < 0.0001), AST (188.73 ± 1.11 U/L vs 248.25 ± 1.40 U/L, P < 0.0001), endotoxin (61.80 ± 12.56 ng/L vs 135.37 ± 30.17 ng/L, P < 0.0001), TNF-α (9.79 ± 1.32 pg/mL vs 20.81 ± 8.58 pg/mL, P = 0.0003), IFN-γ (18.02 ± 5.96 pg/mL vs 30.18 ± 7.60 pg/mL, P = 0.0008) and IL-18 (18.23 ± 7.01 pg/mL vs 40.99 ± 8.25 pg/mL, P < 0.0001). Betaine also improved liver steatosis. The expression levels of TLR4 mRNA or protein in liver tissues were significantly lowered (0.62 ± 0.04 vs 1.45 ± 0.07, P < 0.0001; and 0.65 ± 0.06 vs 1.83 ± 0.13, P < 0.0001). There was a statistical difference of TLR4 mRNA and protein expression between high- and low-dose betaine groups (0.62 ± 0.04 vs 0.73 ± 0.05, P < 0.0001, and 0.65 ± 0.06 vs 0.81 ± 0.09, P < 0.0001).

CONCLUSION: Betaine can prevent the alcohol-induced liver injury effectively and improve the liver function. The expression of TLR4 increases significantly in ethanol-fed rats and betaine administration can inhibit TLR4 expression.

Betaine protects chronic alcohol and omega-3 PUFA-mediated down-regulations of PON1 gene, serum PON1 and homocysteine thiolactonase activities with restoration of liver GSH

BACKGROUND

Paraoxonase (PON1) is an antioxidant enzyme that prevents LDL oxidation as well as detoxifies homocysteine thiolactone (HCTL), both of which can cause atherosclerosis. Chronic alcohol (ETOH) and high omega-3 polyunsaturated fatty acids (omega-3 PUFA) consumption may affect PON1 status presumably via reactive oxygen species by depleting liver glutathione (GSH), whereas betaine may counter their effects. Therefore, we investigated the influence of ETOH, omega-3 PUFA, and betaine on liver GSH, PON1 expression, lipid score, as well as serum PON1 and HCTLase activities.

METHODS

Experimental rats belonging to various dietary groups were pair-fed with Lieber-DeCarli low (2.8% the dietary calories as omega3-fatty acids) and high (13.8% the dietary calories as omega3-fatty acids) menhaden fish alcohol-liquid diets with and without betaine (10 g/l diet) for 8 weeks after which liver PON1 mRNA, GSH, lipid score, and serum PON1, HCTLase, and ALT activities were measured.

RESULTS

High omega-3 PUFA decreased liver PON1 mRNA expression, serum PON1, and HCTLase activity by 23% (p < 0.01), 20% (p < 0.05), and 28% (p < 0.05), respectively compared to the low omega-3 PUFA group. ETOH decreased PON1 mRNA expression by 25 and 30% (p < 0.01) with concomitant 27% (p < 0.05) and 38% (p < 0.01), decrease in liver GSH levels in low and high omega-3 PUFA groups, respectively. Correspondingly, serum PON1 activity decreased by 23% (p < 0.05) and 58% (p < 0.01) while serum HCTLase activity decreased by 25% (p < 0.05) and 59% (p < 0.01) in the low and high omega-3 PUFA ETOH groups, respectively. Betaine restored liver PON1 mRNA expressions in low and high omega-3 PUFA ETOH groups with parallel restorations of PON1 activity and liver GSH. Concomitantly, betaine reduced hepatosteatosis accompanied by alleviation of liver injury caused by chronic alcohol and high omega-3 PUFA.

CONCLUSIONS

Based on these results, we conclude that dietary betaine not only atheroprotective by restoring liver GSH that quenches free radicals, but also may alleviate liver injury by reducing hepatosteatosis.

Assessment of the effect of betaine on p16 and c-myc DNA methylation and mRNA expression in a chemical induced rat liver cancer model

Background

The development and progression of liver cancer may involve abnormal changes in DNA methylation, which lead to the activation of certain proto-oncogenes, such as c-myc, as well as the inactivation of certain tumor suppressors, such as p16. Betaine, as an active methyl-donor, maintains normal DNA methylation patterns. However, there are few investigations on the protective effect of betaine in hepatocarcinogenesis.

Methods

Four groups of rats were given diethylinitrosamine (DEN) and fed with AIN-93G diets supplemented with 0, 10, 20 or 40 g betaine/kg (model, 1%, 2%, and 4% betaine, respectively), while the control group, received no DEN, fed with AIN-93G diet. Eight or 15 weeks later, the expression of p16 and c-myc mRNA was examined by Real-time PCR (Q-PCR). The DNA methylation status within the p16 and c-myc promoter was analyzed using methylation-specific PCR.

Results

Compared with the model group, numbers and areas of glutathione S-transferase placental form (GST-p)-positive foci were decreased in the livers of the rats treated with betaine (P < 0.05). Although the frequency of p16 promoter methylation in livers of the four DEN-fed groups appeared to increase, there is no difference among these groups after 8 or 15 weeks (P > 0.05). Betaine supplementation attenuated the down-regulation of p16 and inhibited the up-regulation of c-myc induced by DEN in a dose-dependent manner (P < 0.01). Meanwhile, increases in levels of malondialdehyde (MDA) and glutathione S-transferase (GST) in model, 2% and 4% betaine groups were observed (P < 0.05). Finally, enhanced antioxidative capacity (T-AOC) was observed in both the 2% and 4% betaine groups.

Conclusion

Our data suggest that betaine attenuates DEN-induced damage in rat liver and reverses DEN-induced changes in mRNA levels.

Role of oxidative stress in alcohol-induced liver injury

Reactive oxygen species (ROS) are highly reactive molecules that are naturally generated in small amounts during the body's metabolic reactions and can react with and damage complex cellular molecules such as lipids, proteins, or DNA. Acute and chronic ethanol treatments increase the production of ROS, lower cellular antioxidant levels, and enhance oxidative stress in many tissues, especially the liver. Ethanol-induced oxidative stress plays a major role in the mechanisms by which ethanol produces liver injury. Many pathways play a key role in how ethanol induces oxidative stress. This review summarizes some of the leading pathways and discusses the evidence for their contribution to alcohol-induced liver injury. Special emphasis is placed on CYP2E1, which is induced by alcohol and is reactive in metabolizing and activating many hepatotoxins, including ethanol, to reactive products, and in generating ROS.

Ethanol blocks adenosine uptake via inhibiting the nucleoside transport system in bronchial epithelial cells

BACKGROUND

Adenosine uptake into cells by nucleoside transporters plays a significant role in governing extracellular adenosine concentration. Extracellular adenosine is an important signaling molecule that modulates many cellular functions via 4 G-protein-coupled receptor subtypes (A(1), A(2A), A(2B), and A(3)). Previously, we demonstrated that adenosine is critical in maintaining airway homeostasis and airway repair and that airway host defenses are impaired by alcohol. Taken together, we hypothesized that ethanol impairs adenosine uptake via the nucleoside transport system.

METHODS

To examine ethanol-induced alteration on adenosine transport, we used a human bronchial epithelial cell line (BEAS-2B). Cells were preincubated for 10 minutes in the presence and absence of varying concentrations of ethanol (EtOH). In addition, some cells were pretreated with S-(4-Nitrobenzyl)-6-thioinosine (100 microM: NBT), a potent adenosine uptake inhibitor. Uptake was then determined by addition of [(3)H]-adenosine at various time intervals.

RESULTS

Increasing EtOH concentrations resulted in increasing inhibition of adenosine uptake when measured at 1 minute. Cells pretreated with NBT effectively blocked adenosine uptake. In addition, short-term EtOH revealed increased extracellular adenosine concentration. Conversely, adenosine transport became desensitized in cells exposed to EtOH (100 mM) for 24 hours. To determine the mechanism of EtOH-induced desensitization of adenosine transport, cAMP activity was assessed in response to EtOH. Short-term EtOH exposure (10 minutes) had little or no effect on adenosine-mediated cAMP activation, whereas long-term EtOH exposure (24 hours) blocked adenosine-mediated cAMP activation. Western blot analysis of lysates from unstimulated BEAS-2B cells detected a single 55 kDa band indicating the presence of hENT1 and hENT2, respectively. Real-time RT-PCR of RNA from BEAS-2B revealed transcriptional expression of ENT1 and ENT2.

CONCLUSIONS

Collectively, these data reveal that acute exposure of cells to EtOH inhibits adenosine uptake via a nucleoside transporter, and chronic exposure of cells to EtOH desensitizes the adenosine transporter to these inhibitory effects of ethanol. Furthermore, our data suggest that inhibition of adenosine uptake by EtOH leads to an increased extracellular adenosine accumulation, influencing the effect of adenosine at the epithelial cell surface, which may alter airway homeostasis.

Effects of S-adenosylmethionine on liver methionine metabolism and steatosis with ethanol-induced liver injury in rats

Background

Hyperhomocysteinemia is implicated in the pathogenesis of various liver diseases. In this study, the effects of S-adenosylmethionine (SAM) on hyperhomocysteinemia and steatosis with ethanol-induced liver injury in rats were examined and their mechanisms were explored.

Methods

Forty-eight female Sprague–Dawley rats were randomly divided into four groups as control, model, low-dose, and high-dose SAM groups. Except the control group, all rats were fed high-fat-containing diet plus ethanol and fish oil gavaged for 8 weeks. SAM was administered by intraperitoneal injection after the 4 weeks’ exposure of ethanol. Serum homocysteine (Hcy), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), triglyceride (TG), tumor necrosis factor α (TNF-α), and transforming growth factor β1 (TGF-β1) levels were determined. The contents of liver malondialdehyde (MDA) and glutathione (GSH) were assayed. Liver histology was also examined. The expressions of TNF-α and TGF-β1 mRNAs in the liver were detected by the reverse transcriptase-polymerase chain reaction assay.

Results

Compared with the control group, the model group rats developed marked liver damage, accompanied by an increase in Hcy, ALT, AST, TC, TG, TNF-α, TGF-β1, and MDA levels. However, the levels of GSH were decreased. These responses were associated with the increased expression of TNF-α and TGF-β1 mRNAs in the livers, as well as the existence of hepatocellular necrosis and neutrophil infiltration in the livers. In treatment groups, SAM provided significant protection from the liver injury induced by alcohol, resulting in a decrease in serum TNF-α, TGF-β1 levels, lipid peroxidation, and the expressions of TNF-α and TGF-β1 mRNAs in the livers, as well as an increase in GSH levels. However, no statistical difference was observed in these parameters between the two different dose treatment groups. In the study, SAM did not affect plasma total homocysteine (tHcy) levels significantly.

Conclusion

SAM prevents alcohol-induced liver injury in rats by reducing liver lipid peroxidation, anti-inflammation, and antihyperplasia. In addition, it does not affect the plasma tHcy levels.

Role of transmethylation reactions in alcoholic liver disease

Alcoholic liver disease is a major health care problem worldwide. Findings from many laboratories, including ours, have demonstrated that ethanol feeding impairs several of the many steps involved in methionine metabolism. Ethanol consumption predominantly results in a decrease in the hepatocyte level of S-adenosylmethionine and the increases in two toxic metabolites, homocysteine and S-adenosylhomocysteine. These changes, in turn, result in serious functional consequences which include decreases in essential methylation reactions via inhibition of various methyltransferases. Of particular interest to our laboratory is the inhibition of three important enzymes, phosphatidylethanolamine methyltransferase, isoprenylcysteine carboxyl methyltransferase and protein L-isoaspartate methyltransferase. Decreased activity of these enzymes results in increased fat deposition, increased apoptosis and increased accumulation of damaged proteins-all of which are hallmark features of alcoholic liver injury. Of all the therapeutic modalities available, betaine has been shown to be the safest, least expensive and most effective in attenuating ethanol-induced liver injury. Betaine, by virtue of aiding in the remethylation of homocysteine, removes both toxic metabolites (homocysteine and S-adenosylhomocysteine), restores S-adenosylmethionine level, and reverses steatosis, apoptosis and damaged proteins accumulation. In conclusion, betaine appears to be a promising therapeutic agent in relieving the methylation and other defects associated with alcoholic abuse.

Immunological response in alcoholic liver disease

The development of alcoholic liver disease (ALD) can be attributed to many factors that cause damage to the liver and alter its functions. Data collected over the last 30 years strongly suggests that an immune component may be involved in the onset of this disease. This is best evidenced by the detection of circulating autoantibodies, infiltration of immune cells in the liver, and the detection of hepatic aldehyde modified proteins in patients with ALD. Experimentally, there are numerous immune responses that occur when proteins are modified with the metabolites of ethanol. These products are formed in response to the high oxidative state of the liver during ethanol metabolism, causing the release of many inflammatory processes and potential of necrosis or apoptosis of liver cells. Should cellular proteins become modified with these reactive alcohol metabolites and be recognized by the immune system, then immune responses may be initiated. Therefore, it was the purpose of this article to shed some insight into how the immune system is involved in the development and/or progression of ALD.

Effects of Chronic Ethanol Consumption on Brain Synaptosomes and Protective Role of Betaine

To evaluate the cytotoxic effects of chronic ethanol consumption on brain cerebral synaptosomes and preventive role of betaine as a methyl donor and S-adenosylmethionine precursor, 24 male Wistar rats were divided into three groups: control, ethanol (8 g/kg/day) and ethanol plus betaine(0.5% w/v) group. Animals were fed 60 ml/diet per day for two months, then sacrificed. Malondialdehyde (MDA), protein carbonyl contents and adenosine deaminase (ADA) activities were determined in synaptosomal/mitochondrial enriched fraction isolated from rat cerebral cortexes. When compared to controls, ethanol containing diet significantly increased MDA levels (P < 0.05), also increased protein carbonyl levels and adenosine deaminase activities. But these were not statistically significant (P > 0.05). However, adding betaine to ethanol containing diet caused a significant decrease in MDA, protein carbonyl levels and adenosine deaminase activities (P < 0.05). These results indicate that betaine may appear as a protective nutritional agent against cytotoxic brain damage induced by chronic ethanol consumption.

S-adenosylmethionine attenuates hepatic lipid synthesis in micropigs fed ethanol with a folate-deficient diet

BACKGROUND

To demonstrate a causative role of abnormal methionine metabolism in the pathogenesis of alcoholic steatosis, we measured the effects on hepatic lipid synthesis of supplementing ethanol and folate-deficient diets with S-adenosylmethionine (SAM), a metabolite that regulates methionine metabolism.

METHODS

Yucatan micropigs were fed folate-deficient diets as control, with ethanol at 40% of kcal, and with ethanol supplemented with SAM at 0.4 g/1,000 kcal for 14 weeks. Histopathology, triglyceride levels and transcripts, and protein levels of the regulatory signals of hepatic lipid synthesis were measured in terminal omental adipose and liver samples.

RESULTS

Feeding ethanol at 40% of kcal with folate-deficient diets for 14 weeks increased and supplemental SAM maintained control levels of liver and plasma triglyceride. Serum adiponectin, liver transcripts of adiponectin receptor-1 (AdipoR1), and phosphorylated adenosine monophosphate kinase-beta (p-AMPKbeta) were each reduced by ethanol feeding and were sustained at normal levels by SAM supplementation of the ethanol diets. Ethanol feeding activated and SAM supplementation maintained control levels of ER stress-induced transcription factor sterol regulatory element-binding protein-1c (SREBP-1c) and its targeted transcripts of lipid synthesizing enzymes acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and glycerol-3-phosphate acyltransferase (GPAT).

CONCLUSIONS

Ethanol feeding with a folate-deficient diet stimulates hepatic lipid synthesis by down-regulating adiponectin-mediated pathways of p-AMPK to increase the expression of nSREBP-1c and its targeted lipogenic enzymes. Preventing abnormal hepatic methionine metabolism by supplementing ethanol diets with SAM reduces liver triglyceride levels by up-regulation of adiponectin-mediated pathways to decrease fatty acid and triglyceride synthesis. This study demonstrates that ethanol-induced hepatic lipid synthesis is mediated in part by abnormal methionine metabolism, and strengthens the concept that altered methionine metabolism plays an integral role in the pathogenesis of steatosis.

Role of S-adenosylmethionine, folate, and betaine in the treatment of alcoholic liver disease: summary of a symposium

This report is a summary of a symposium on the role of S-adenosylmethionine (SAM), betaine, and folate in the treatment of alcoholic liver disease (ALD), which was organized by the National Institute on Alcohol Abuse and Alcoholism in collaboration with the Office of Dietary Supplements and the National Center for Complementary and Alternative Medicine of the National Institutes of Health (Bethesda, MD) and held on 3 October 2005. SAM supplementation may attenuate ALD by decreasing oxidative stress through the up-regulation of glutathione synthesis, reducing inflammation via the down-regulation of tumor necrosis factor-alpha and the up-regulation of interleukin-10 synthesis, increasing the ratio of SAM to S-adenosylhomocysteine (SAH), and inhibiting the apoptosis of normal hepatocytes and stimulating the apoptosis of liver cancer cells. Folate deficiency may accelerate or promote ALD by increasing hepatic homocysteine and SAH concentrations; decreasing hepatic SAM and glutathione concentrations and the SAM-SAH ratio; increasing cytochrome P4502E1 activation and lipid peroxidation; up-regulating endoplasmic reticulum stress markers, including sterol regulatory element-binding protein-1, and proapoptotic gene caspase-12; and decreasing global DNA methylation. Betaine may attenuate ALD by increasing the synthesis of SAM and, eventually, glutathione, decreasing the hepatic concentrations of homocysteine and SAH, and increasing the SAM-SAH ratio, which can trigger a cascade of events that lead to the activation of phosphatidylethanolamine methyltransferase, increased phosphatidylcholine synthesis, and formation of VLDL for the export of triacylglycerol from the liver to the circulation. Additionally, decreased concentrations of homocysteine can down-regulate endoplasmic reticulum stress, which leads to the attenuation of apoptosis and fatty acid synthesis.

Accumulation of proteins bearing atypical isoaspartyl residues in livers of alcohol-fed rats is prevented by betaine administration: effects on protein-L-isoaspartyl methyltransferase activity

BACKGROUND/AIMS

Protein-L-isoaspartyl methyltransferase (PIMT) is a methyltransferase that plays a crucial role in the repair of damaged proteins. In this study, we investigated whether ethanol exposure causes an accumulation of modified proteins bearing atypical isoaspartyl residues that may be related to impaired PIMT activity. We further sought to determine whether betaine administration could prevent the accumulation of these types of damaged proteins.

METHODS

Livers of male Wistar rats, fed the Lieber DeCarli control, ethanol or 1% betaine-supplemented diets for 4 weeks, were processed for PIMT-related analyses.

RESULTS

We observed a significant increase in the accumulation of modified proteins bearing isoaspartyl residues, i.e. the substrates for PIMT, in homogenate samples and various subcellular fractions of livers from ethanol-fed rats. Betaine supplementation prevented this accumulation of damaged proteins. In contrast, ethanol exposure induced no changes in the PIMT enzyme activity levels as compared to controls. The accumulation of damaged proteins negatively correlated with hepatic S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH) ratios.

CONCLUSIONS

Ethanol consumption results in the accumulation of modified proteins bearing atypical isoaspartyl residues via impaired in vivo PIMT activity. Betaine administration prevents the ethanol-induced accumulation of isoaspartyl-containing proteins by restoring the PIMT-catalyzed protein repair reaction through normalizing the hepatocellular SAM:SAH ratios.

Betaine attenuates alcoholic steatosis by restoring phosphatidylcholine generation via the phosphatidylethanolamine methyltransferase pathway

BACKGROUND/AIMS

Previous studies in our laboratory implicated ethanol-induced decreases in hepatocellular S-adenosylmethionine to S-adenosylhomocysteine (SAM:SAH) ratios in lowering the activity of phosphatidylethanolamine methyltransferase (PEMT), which is associated with the generation of steatosis. Further in vitro studies showed that betaine supplementation could correct these alterations in the ratio as well as attenuate alcoholic steatosis. Therefore, we sought to determine whether the protective effect of betaine is via its effect on PEMT activity.

METHODS

Male Wistar rats were fed the Lieber DeCarli control or ethanol diet with or without 1% betaine supplementation for 4 weeks.

RESULTS

We observed that ethanol feeding resulted in decreased phosphatidylcholine (PC) production by a PEMT-catalyzed reaction. Betaine supplementation corrected the ethanol-induced decrease in hepatic SAM:SAH ratios and by normalizing PC production via the PEMT-mediated pathway, significantly reduced fatty infiltration associated with ethanol consumption. This restoration of hepatocellular SAM:SAH ratio by betaine supplementation was associated with increases in the activity, enzyme mass and gene expression of the enzyme, betaine homocysteine methyltransferase (BHMT), that remethylates homocysteine.

CONCLUSIONS

Betaine, by virtue of promoting an alternate remethylation pathway, restores SAM:SAH ratios that, in turn, correct the defective cellular methylation reaction catalyzed by PEMT resulting in protection against the generation of alcoholic steatosis.