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

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.

Protective Effects of S-Adenosylmethionine and Its Combinations With Taurine and/or Betaine Against Lipopolysaccharide or Polyinosinic-polycytidylic Acid-induced Acute Hepatotoxicity

BACKGROUND

Several mechanisms for the pathogenesis of many liver diseases are related with oxidative stress, endotoxins, and infections by many microorganisms. These can lead to chronic hepatitis, cirrhosis, and even liver cancer. The aim of this study was to evaluate the effects of S-adenosylmethionine (SAMe) and its combinations with taurine and/or betaine against hepatotoxicites induced by lipopolysaccharide (LPS) or polyinosinic-polycytidylic acid (polyI:C).

METHODS

RAW 264.7 macrophage cells and seven-week-old male C57BL/6 mice were pretreated with SAMe (SAM or AdoMet), taurine, and/or betaine. In order to mimic hepatic injury like endotoxemia or viral infection, cells and mice were treated with LPS or polyI:C. Concentrations of glutathione (GSH), mRNA expressions of GSH synthesizing enzymes, and inflammatory markers were measured by biochemical assays and quantitative real-time PCR.

RESULTS

In RAW 264.7 cells and mice, pretreatment of SAMe alone or SAMe with taurine and/or betaine attenuated the decrease in GSH levels and mRNA expressions of GSH synthesizing enzymes. In addition, pretreatment of SAMe with taurine and/or betaine prevented the excessive increase in inflammatory mediators produced by LPS or polyI:C treatment.

CONCLUSIONS

Treatment with SAMe in combination with taurine and betaine, would have anti-oxidant functions in addition to anti-inflammatory action against bacterial and/or viral inflammation.

Dietary supplementation in patients with alcoholic liver disease: a review on current evidence

BACKGROUND

Alcoholic liver disease (ALD) is one of the main causes of liver disease worldwide. Although the pathogenesis of ALD has not yet been well elucidated, the oxidative metabolites of ethanol such as acetaldehyde and reactive oxygen species play a pivotal role in the clinical and pathological spectrum of the disease. This review summarizes the existing evidences on dietary supplements considered to have antioxidant, and/or anti-inflammatory properties, and their role in the management of ALD and the proposed mechanisms.

DATA SOURCES

The present study reviewed all studies published in PubMed, ScienceDirect and Scopus, from 1959 to 2015, indicating the role of different dietary supplementation in attenuation of many pathophysiological processes involved in development and progression of ALD. Full-texts of citations were used except for those that were published in languages other than English.

RESULTS

Significant progress has been made to understand the key events and molecular players for the onset and progression of ALD from both experimental and clinical studies; however, there is no successful treatment currently available. The present review discussed the role of a variety of dietary supplements (e.g. vitamin A, carotenoids, vitamins B3, C and E, in addition to antioxidants and anti-inflammatory agents) in treating ALD. It has been shown that supplementation with some carotenoids, vitamin B3, vitamin C, silymarin, curcumin, probiotics, zinc, S-adenosylmethionine and garlic may have potential beneficial effects in animal models of ALD; however, the number of clinical studies is very limited. In addition, supplementation should be accompanied with alcohol cessation.

CONCLUSIONS

Since oxidative stress and inflammation are involved in the pathogenesis of ALD, dietary supplements that can modulate these pathologies could be useful in the treatment of ALD. In addition to alcohol cessation, these supplements have shown beneficial effects on animal models of ALD. Clinical trials are needed to validate the beneficiary role of these supplements in patients with ALD.

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.

S-adenosylmethionine reduces airway inflammation and fibrosis in a murine model of chronic severe asthma via suppression of oxidative stress

Increased oxidative stress has an important role in asthmatic airway inflammation and remodeling. A potent methyl donor, S-adenosylmethionine (SAMe), is known to protect against tissue injury and fibrosis through modulation of oxidative stress. The aim of this study was to evaluate the effect of SAMe on airway inflammation and remodeling in a murine model of chronic asthma. A mouse model was generated by repeated intranasal challenge with ovalbumin and Aspergillus fungal protease twice a week for 8 weeks. SAMe was orally administered every 24 h for 8 weeks. We performed bronchoalveolar lavage (BAL) fluid analysis and histopathological examination. The levels of various cytokines and 4-hydroxy-2-nonenal (HNE) were measured in the lung tissue. Cultured macrophages and fibroblasts were employed to evaluate the underlying anti-inflammatory and antifibrotic mechanisms of SAMe. The magnitude of airway inflammation and fibrosis, as well as the total BAL cell counts, were significantly suppressed in the SAMe-treated groups. A reduction in T helper type 2 pro-inflammatory cytokines and HNE levels was observed in mouse lung tissue after SAMe administration. Macrophages cultured with SAMe also showed reduced cellular oxidative stress and pro-inflammatory cytokine production. Moreover, SAMe treatment attenuated transforming growth factor-β (TGF-β)-induced fibronectin expression in cultured fibroblasts. SAMe had a suppressive effect on airway inflammation and fibrosis in a mouse model of chronic asthma, at least partially through the attenuation of oxidative stress and TGF-β-induced fibronectin expression. The results of this study suggest a potential role for SAMe as a novel therapeutic agent in chronic asthma.

Folic Acid Supplementation Mitigates Alzheimer's Disease by Reducing Inflammation: A Randomized Controlled Trial

Background/Aims. Low serum folate levels can alter inflammatory reactions. Both phenomena have been linked to Alzheimer's disease (AD), but the effect of folic acid on AD itself is unclear. We quantified folate supplementation's effect on inflammation and cognitive function in patients with AD over the course of 6 months. Methods. Patients newly diagnosed with AD (age > 60 years; n = 121; mild to severe; international criteria) and being treated with donepezil were randomly assigned into two groups with (intervention group) or without (control group) supplemental treatment with folic acid (1.25 mg/d) for 6 months. The Mini-Mental State Examination (MMSE) was administered to all patients at baseline and follow-up, and blood samples were taken before and after treatment. We quantified serum folate, amyloid beta (Aβ), interleukin-6 (IL-6), tumor necrosis factor α (TNFα), plasma homocysteine (Hcy), S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), and the mRNA levels of presenilin (PS), IL-6, and TNFα in leukocytes. Data were analyzed using a repeated-measures mixed model. Results. The mean MMSE was slightly increased in the intervention group compared to that in the control group (P < 0.05). Posttreatment, plasma SAM and SAM/SAH levels were significantly higher (P < 0.05), while Aβ₄₀, PS1-mRNA, and TNFα-mRNA levels were lower in the intervention group than in the control group (P < 0.05). The Aβ₄₂/Aβ₄₀ ratio was also higher in the intervention group (P < 0.05). Conclusions. Folic acid is beneficial in patients with AD. Inflammation may play an important role in the interaction between folic acid and AD. This trial is registered with clinical trial registration number ChiCTR-TRC-13003246.

Compounds of the sphingomyelin-ceramide-glycosphingolipid pathways as secondary messenger molecules: new targets for novel therapies for fatty liver disease and insulin resistance

The compounds of sphingomyelin-ceramide-glycosphingolipid pathways have been studied as potential secondary messenger molecules in various systems, along with liver function and insulin resistance. Secondary messenger molecules act directly or indirectly to affect cell organelles and intercellular interactions. Their potential role in the pathogenesis of steatohepatitis and diabetes has been suggested. Data samples collected from patients with Gaucher's disease, who had high levels of glucocerebroside, support a role for compounds from these pathways as a messenger molecules in the pathogenesis of fatty liver disease and diabetes. The present review summarizes some of the recent data on the role of glycosphingolipid molecules as messenger molecules in various physiological and pathological conditions, more specifically including insulin resistance and fatty liver disease.

Traumatic Brain Injury Alters Methionine Metabolism: Implications for Pathophysiology

Methionine is an essential proteinogenic amino acid that is obtained from the diet. In addition to its requirement for protein biosynthesis, methionine is metabolized to generate metabolites that play key roles in a number of cellular functions. Metabolism of methionine via the transmethylation pathway generates S-adenosylmethionine (SAM) that serves as the principal methyl (−CH₃) donor for DNA and histone methyltransferases (MTs) to regulate epigenetic changes in gene expression. SAM is also required for methylation of other cellular proteins that serve various functions and phosphatidylcholine synthesis that participate in cellular signaling. Under conditions of oxidative stress, homocysteine (which is derived from SAM) enters the transsulfuration pathway to generate glutathione, an important cytoprotective molecule against oxidative damage. As both experimental and clinical studies have shown that traumatic brain injury (TBI) alters DNA and histone methylation and causes oxidative stress, we examined if TBI alters the plasma levels of methionine and its metabolites in human patients. Blood samples were collected from healthy volunteers (HV; n = 20) and patients with mild TBI (mTBI; GCS > 12; n = 20) or severe TBI (sTBI; GCS < 8; n = 20) within the first 24 h of injury. The levels of methionine and its metabolites in the plasma samples were analyzed by either liquid chromatography-mass spectrometry or gas chromatography-mass spectrometry (LC-MS or GC-MS). sTBI decreased the levels of methionine, SAM, betaine and 2-methylglycine as compared to HV, indicating a decrease in metabolism through the transmethylation cycle. In addition, precursors for the generation of glutathione, cysteine and glycine were also found to be decreased as were intermediate metabolites of the gamma-glutamyl cycle (gamma-glutamyl amino acids and 5-oxoproline). mTBI also decreased the levels of methionine, α-ketobutyrate, 2 hydroxybutyrate and glycine, albeit to lesser degrees than detected in the sTBI group. Taken together, these results suggest that decreased levels of methionine and its metabolic products are likely to alter cellular function in multiple organs at a systems level.

Alcoholic Liver Disease: A Comprehensive Review

Alcoholic liver disease, a leading cause of morbidity, mortality, and cirrhosis, can range from simple steatosis to hepatocellular carcinoma. Multiple mechanisms such as oxidative stress, mitochondrial dysfunction, and alteration in gut-liver axis have been proposed for the pathogenesis of alcoholic liver disease. Based on different prognostic models, alcoholic hepatitis patients can be stratified into sub-groups and specific pharmacological therapy can be started. Alcohol abstinence has a clear cut mortality benefit and nutritional support is very important as most of the patients are malnourished and in a hypercatabolic state. Other than conventional glucocorticoids and pentoxifylline, newer agents and combination therapy can be used in severe alcoholic hepatitis in patients not responsive to conventional glucocorticoid therapy. Liver transplantation improves survival in advanced alcoholic cirrhosis and it can be an option in severe alcoholic hepatitis patients who are not responding to other medical therapies. Whether early transplantation can improve the survival compared with the conventional waiting period of 6 months is an active area of investigation. This is due to the fact that most of the disease-related mortality occurs in the first 2 months.

Betaine Increases the Butyrylcholinesterase Activity in Rat Plasma

The physiological function of butyrylcholinesterase (EC 3.1.1.8, BChE) is not clearly understood, but a role was suggested in the fat utilization process, resulting in positive correlation between plasma triglyceride (TG) levels and BChE activity. Consequently we tested the hypothesis that regular intake of betaine, a natural compound intervening in the liver TG metabolism could influence the BChE activity. The BChE activity was estimated spectrophotometrically in plasma of rats fed with betaine enriched standard (B) or high-fat diet (HFB). The results confirmed decreased TG plasma levels after betaine treatment independently on the type of diet (0.15±0.03 (B) vs. 0.27±0.08 (control) mmol/l; p=0.003 and 0.13±0.03 (HFB) vs. 0.27±0.08 (control) mmol/l; p=0.005). The BChE activity increased significantly with betaine administration, however the change was more distinct in the HFB group (0.84±0.34 (HFB) vs. 0.22±0.04 (control) O.D./min/mg; p<0.001 and 0.41±0.11 (B) vs. 0.22±0.04 (control) O.D./min/mg; p=0.001). In conclusion, betaine intake led to elevated BChE activity in plasma and this effect was potentiated by the HF diet. Since betaine is in general used as a supplement in the treatment of liver diseases accompanied by TG overload, its impact on the BChE activity in the role of the liver function marker should be taken into account.

Molecular basis of alcoholic fatty liver disease: From incidence to treatment

Alcoholic liver diseases have complex and multiple pathogenic mechanisms but still no effective treatment. Steatosis or alcoholic fatty liver disease (AFLD) has a widespread incidence and is the first step in the progression to more severe stages of alcoholic liver disease, with concomitant increases in morbidity and mortality rates. The ways in which this progression occurs and why some individuals are susceptible are still unanswered scientific questions. Research with animal models and clinical evidence have shown that it is a multifactorial disease that involves interactions between lipid metabolism, inflammation, the immune response and oxidative stress. Each of these pathways provides a better understanding of the pathogenesis of AFLD and contributes to the development of therapeutic strategies. This review emphasizes the importance of research on alcoholic steatosis based on incidence data, key pathogenic mechanisms and therapeutic interventions, and discusses perspectives on the progression of this disease.

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.

Effect of rye bread enriched with tomato pomace on fat absorption and lipid metabolism in rats fed a high-fat diet

BACKGROUND

Tomato pomace (TP), obtained as a residue of tomato processing, was used to enrich rye bread (RB). The sensory profile of this functional bread (RB+TP) was characterised, and its fat absorption and lipid metabolism properties in high-fat-fed rats were studied.

RESULTS

Intake of the HF diet containing RB, RB+TP, or TP alone increased faecal energy and fat excretion, but did not affect animal growth or visceral fat weight. Both RB and RB+TP diminished the negative impact of the HF diet, lowering the atherogenic index of plasma (AIP) and the total liver lipid contents by 31.6% and 24%, respectively. The experimental diets had no effect on liver S-adenosylhomocysteine (SAH) concentrations or on the S-adenosylmethionine (SAM) to SAH ratio, though the lowest SAM levels were observed in the HF+TP group. No significant differences were detected in blood homocysteine, triglycerides, glucose or insulin levels.

CONCLUSIONS

Although RB+TP incorporated into a HF diet may lead to a decrease in AIP and total liver lipid content, this effect does not depend on the components of TP, but rather on the RB ingredients. However, pure TP, in the doses used in this study, may potentially play a role in the energy balance via faecal loss of lipids.

Translational Implications of the Alcohol-Metabolizing Enzymes, Including Cytochrome P450-2E1, in Alcoholic and Nonalcoholic Liver Disease

Fat accumulation (hepatic steatosis) in alcoholic and nonalcoholic fatty liver disease is a potentially pathologic condition which can progress to steatohepatitis (inflammation), fibrosis, cirrhosis, and carcinogenesis. Many clinically used drugs or some alternative medicine compounds are also known to cause drug-induced liver injury, which can further lead to fulminant liver failure and acute deaths in extreme cases. During liver disease process, certain cytochromes P450 such as the ethanol-inducible cytochrome P450-2E1 (CYP2E1) and CYP4A isozymes can be induced and/or activated by alcohol and/or high-fat diets and pathophysiological conditions such as fasting, obesity, and diabetes. Activation of these P450 isozymes, involved in the metabolism of ethanol, fatty acids, and various drugs, can produce reactive oxygen/nitrogen species directly and/or indirectly, contributing to oxidative modifications of DNA/RNA, proteins and lipids. In addition, aldehyde dehydrogenases including the mitochondrial low Km aldehyde dehydrogenase-2 (ALDH2), responsible for the metabolism of acetaldehyde and lipid aldehydes, can be inactivated by various hepatotoxic agents. These highly reactive acetaldehyde and lipid peroxides, accumulated due to ALDH2 suppression, can interact with cellular macromolecules DNA/RNA, lipids, and proteins, leading to suppression of their normal function, contributing to DNA mutations, endoplasmic reticulum stress, mitochondrial dysfunction, steatosis, and cell death. In this chapter, we specifically review the roles of the alcohol-metabolizing enzymes including the alcohol dehydrogenase, ALDH2, CYP2E1, and other enzymes in promoting liver disease. We also discuss translational research opportunities with natural and/or synthetic antioxidants, which can prevent or delay the onset of inflammation and liver disease.

Liver toxicity in colorectal cancer patients treated with first-line FOLFIRI-containing regimen: a single institution experience

BACKGROUND

Chemotherapy-induced toxic liver injury is a relevant issue in the clinical management of patients affected with metastatic colorectal cancer (mCRC). This retrospective study evaluated patterns of liver toxicity in patients treated with FOLinic acid, Fluorouracil, IRInotecan (FOLFIRI)-based regimens.

METHODS

One hundred and fifty-six mCRC patients treated at the University Campus Bio-Medico between January 2003 and January 2013 were included in this retrospective analysis. All patients received a FOLFIRI backbone-based chemotherapy. Basal liver enzymes levels were assessed before starting the treatment and before every therapy course. R ratio and the aspartate aminotransferase/alanine aminotransferase ratio were calculated.

RESULTS

Ninety-one patients were male versus 55 female, and the median age of the population was 62 years (range: 38-83). Most patients had liver involvement at the beginning of first-line regimen (101 patients, 64.74%) and 59 patients had received a previous 5-FU based therapy in the adjuvant setting (37.82%). Aspartate aminotransferase level (167.87 vs 41.05 U/l; p < 0.001), Alanine aminotransferase level (94.48 vs 39.80 U/l; p = 0.004) and alkaline phosphatase (289.0 vs 172.44 U/l; p = 0.02) were significantly increased during the first 3 months of treatment. In the entire population, the calculated R ratio was 3.96 (95% CI: 3.25-4.51). In all three regimens, the calculated R ratio was between 2 and 5, without any statistical differences.

CONCLUSIONS

FOLFIRI-based hepatotoxicity has been indirectly defined as a mixed pattern injury in all three regimens evaluated.

Sulfur as a signaling nutrient through hydrogen sulfide

Hydrogen sulfide (H₂S) has emerged as an important signaling molecule with beneficial effects on various cellular processes affecting, for example, cardiovascular and neurological functions. The physiological importance of H₂S is motivating efforts to develop strategies for modulating its levels. However, advancement in the field of H₂S-based therapeutics is hampered by fundamental gaps in our knowledge of how H₂S is regulated, its mechanism of action, and its molecular targets. This review provides an overview of sulfur metabolism; describes recent progress that has shed light on the mechanism of H₂S as a signaling molecule; and examines nutritional regulation of sulfur metabolism, which pertains to health and 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.

The plasma S-adenosylmethionine level is associated with the severity of hepatitis B-related liver disease

Alterations in methionine metabolism that involve changes in the plasma S-adenosylmethionine (SAMe) level occur in chronic liver diseases. However, no evidence is available on whether circulating SAMe is involved in the development of liver cirrhosis and liver cancer. Cross-sectional data on clinical characteristics and plasma SAMe were collected for 130 cases of chronic hepatitis B (CHB) and HCC as well as for normal volunteers. Univariate and multivariate linear regression and receiver operating characteristic curves were introduced to determine their correlations. Serum ALB and PT levels were independent clinical factors that were correlated with the plasma SAMe levels in CHB and HCC patients. A higher SAMe concentration was observed in the HCC than in the normal and CHB. By exploring the association of the Child-Pugh score with the plasma SAMe level, we found a higher SAMe level at advanced Stage C than at stage A in CHB and HCC patients. We further assessed the diagnostic performance of SAMe with respect to the stages of liver fibrosis and Child-Pugh stage. The AUROC of SAMe for the prediction of cirrhosis was 0.721, and the sensitivity and specificity was 0.707 and 0.769, respectively. The AUROC of plasma SAMe to predict Child-Pugh stage C was 0.706 in patients with CHB and 0.825 in HCC patients. The sensitivity was 0.467 and 0.800, respectively; the specificity was 0.904 and 0.781, respectively. The plasma SAMe level was positively correlated with the severity of liver disease and might be a potential noninvasive biomarker.

Acid sphingomyelinase-ceramide system in steatohepatitis: a novel target regulating multiple pathways

Steatohepatitis (SH) is an intermediate stage of fatty liver disease and is one of the most common causes of chronic liver disease worldwide that may progress to cirrhosis and liver cancer. SH encompasses alcoholic and non-alcoholic steatohepatitis, the latter being of particular concern as it is associated with obesity and insulin resistance and has become a major cause of liver transplantation. The molecular mechanisms governing the transition from steatosis to SH are not fully understood. Here we discuss emerging data indicating that the acid sphingomyelinase (ASMase), a specific mechanism of ceramide generation, is required for the activation of key pathways that regulate steatosis, fibrosis and lipotoxicity, including endoplasmic reticulum stress, autophagy and lysosomal membrane permeabilization. Moreover, ASMase modulates alterations of the methionine cycle and phosphatidylcholine homeostasis, two crucial events involved in SH that regulate methylation reactions, antioxidant defence and membrane integrity. These new findings suggest that targeting ASMase in combination with restoring methionine metabolism and phosphatidylcholine levels may be of utility in the treatment of SH.

Maternal omega-3 fatty acid supplementation on vitamin B12 rich diet improves brain omega-3 fatty acids, neurotrophins and cognition in the Wistar rat offspring

INTRODUCTION

The consequences of wide spread vegetarianism due to low vitamin B12 on brain development and functioning is gaining importance. However, there are no studies which have evaluated exclusively vitamin B12 supplementation during pregnancy on brain growth. A series of our animal studies have documented adverse effects of maternal micronutrient imbalance on brain neurotrophins and its amelioration by omega-3 fatty acids. Therefore, the present study investigated the effect of maternal supplementation with vitamin B12 alone and B12 plus omega-3 fatty acid on pup brain fatty acids and neurotrophins at birth and 3 mo of age.

METHODS AND RESULTS

Pregnant Wistar rats and their male offspring were assigned to 3 dietary groups: Control (normal vitamin B12 (25 μg/kg), vitamin B12 supplemented (BS) (50 μg/kg), vitamin B12 supplemented with omega-3 fatty acid (BSO) till 3 month of age. Maternal vitamin B12 supplementation (BS) increased brain BDNF (protein and mRNA) and DHA levels in pups at birth and in the hippocampus at 3 month of age (BDNF only). These effects were further enhanced by omega-3 fatty acid supplementation to vitamin B12 supplemented group. The spatial memory performance was found to be enhanced in BSO group which was characterised by less number of errors in radial eight arm maze.

CONCLUSION

Our results indicate that a combination of omega-3 fatty acid and vitamin B12 enriched diet may exert beneficial effects on synaptic plasticity and cognition, which may prove beneficial for mental health, particularly in preventing neurocognitive disorders.

Mallory-Denk Body (MDB) formation modulates Ufmylation expression epigenetically in alcoholic hepatitis (AH) and non-alcoholic steatohepatitis (NASH)

Promoter CpG island hypermethylation is an important mechanism for inactivating key cellular enzymes that mediate epigenetic processes in hepatitis-related hepatocellular carcinoma (HCC). The ubiquitin-fold modifier 1 (Ufm1) conjugation pathway (Ufmylation) plays an essential role in protein degradation, protein quality control and signal transduction. Previous studies showed that the Ufmylation pathway was downregulated in alcoholic hepatitis (AH), non-alcoholic steatohepatitis (NASH) and in mice fed DDC, resulting in the formation of Mallory-Denk Bodies (MDBs). In this study, we further discovered that betaine, a methyl donor, fed together with DDC significantly prevents the increased expression of Ufmylation in drug-primed mice fed DDC. Betaine significantly prevented transcript silencing of Ufm1, Uba5 and UfSP1 where MDBs developed and also prevented the increased expression of FAT10 and LMP7 caused by DDC re-fed mice. Similar downregulation of Ufmylation was observed in multiple AH and NASH biopsies which had formed MDBs. The DNA methylation levels of Ufm1, Ufc1 and UfSP1 in the promoter CpG region were significantly increased both in AH and NASH patients compared to normal subjects. DNA (cytosine-5-)-methyltransferase 1 (DNMT1) and DNA (cytosine-5-)-methyltransferase 3 beta (DNMT3B) mRNA levels were markedly upregulated in AH and NASH patients, implying that the maintenance of Ufmylation methylation might be mediated by DNMT1 and DNMT3B together. These data show that MDB formation results from Ufmylation expression epigenetically in AH and NASH patients. Promoter CpG methylation may be a major mechanism silencing Ufmylation expression.

Inhibition of spermidine/spermine N1-acetyltransferase activity: a new therapeutic concept in rheumatoid arthritis

OBJECTIVE

Changes in polyamine-modulated factor 1 (PMF-1) promoter methylation might favor the expression of spermidine/spermine N1-acetyltransferase 1 (SSAT-1), causing excessive consumption of S-adenosyl methionine (SAM). This study was undertaken to evaluate the effect of SSAT-1 activity inhibition, either alone or in combination with SAM.

METHODS

Synovial fibroblasts were isolated from patients with rheumatoid arthritis (RA) or osteoarthritis (OA). PMF-1 promoter methylation was determined by pyrosequencing. Small interfering RNAs (siRNAs) against SSAT-1 were transfected weekly in RA synovial fibroblasts (RASFs). In addition, synovial fibroblasts were treated with diminazene aceturate (DA), an inhibitor of SSAT-1. SSAT-1, 5-methylcytosine (5-MeC), adenosyl methionine decarboxylase (AMD), PMF-1, DNA methyltransferase 1 (DNMT-1), CXCL12, β1 integrin, and CD44 levels were measured by flow cytometry. Putrescine levels were determined by colorimetry. Levels of matrix metalloproteinases were measured by enzyme-linked immunosorbent assay. Cell adhesion was tested. The SCID mouse model of RA was used to monitor the invasiveness of RASFs.

RESULTS

RASFs showed elevated SSAT-1, AMD, and PMF-1 levels. However, PMF-1 promoter methylation was unchanged. Transfection of siRNA targeting SSAT-1 increased 5-MeC levels within 21 days. Similarly, DA increased 5-MeC levels in RASFs. In addition, DA increased the levels of DNMT-1, decreased the levels of AMD, putrescine, activation markers, and MMP-1, and altered the adhesion of RASFs. DA was more efficient in RASFs with higher levels of SSAT-1. Most interestingly, the combination of DA and SAM reduced the invasiveness of RASFs by 70%.

CONCLUSION

The use of DA alone or in combination with SAM/L-methionine might introduce a new therapeutic concept in RA. This is the first therapy that would directly target RASFs and thereby inhibit ongoing joint destruction.

Paternal alcohol exposure reduces alcohol drinking and increases behavioral sensitivity to alcohol selectively in male offspring

Alcohol use disorder (AUD) is heritable, but the genetic basis for this disease remains poorly understood. Although numerous gene variants have been associated with AUD, these variants account for only a small fraction of the total risk. The idea of inheritance of acquired characteristics, i.e. “epigenetic inheritance,” is re-emerging as a proven adjunct to traditional modes of genetic inheritance. We hypothesized that alcohol drinking and neurobiological sensitivity to alcohol are influenced by ancestral alcohol exposure. To test this hypothesis, we exposed male mice to chronic vapor ethanol or control conditions, mated them to ethanol-naïve females, and tested adult offspring for ethanol drinking, ethanol-induced behaviors, gene expression, and DNA methylation. We found that ethanol-sired male offspring had reduced ethanol preference and consumption, enhanced sensitivity to the anxiolytic and motor-enhancing effects of ethanol, and increased Bdnf expression in the ventral tegmental area (VTA) compared to control-sired male offspring. There were no differences among ethanol- and control-sired female offspring on these assays. Ethanol exposure also decreased DNA methylation at the BdnfÆpromoter of sire's germ cells and hypomethylation was maintained in the VTA of both male and female ethanol-sired offspring. Our findings show that paternal alcohol exposure is a previously unrecognized regulator of alcohol drinking and behavioral sensitivity to alcohol in male, but not female, offspring. Paternal alcohol exposure also induces epigenetic alterations (DNA hypomethylation) and gene expression changes that persist in the VTA of offspring. These results provide new insight into the inheritance and development of alcohol drinking behaviors.

Impaired one carbon metabolism and DNA methylation in alcohol toxicity

Excessive alcohol consumption is a prominent problem and one of the major causes of mortality and morbidity around the world. Long-term, heavy alcohol consumption is associated with a number of deleterious health consequences, such as cancer, heart and liver disease, a variety of neurological, cognitive, and behavioral deficits. Alcohol consumption is also associated with developmental defects. The causes of alcohol-induced toxicity are presently unclear. One of the mechanisms underlying alcohol toxicity has to do with its interaction with folic acid/homocysteine or one-carbon metabolism (OCM). OCM is a major donor of methyl groups for methylation, particularly DNA methylation critical for epigenetic regulation of gene expression, and its disturbance may compromise DNA methylation, thereby affecting gene expression. OCM disturbance mediated by nutrient deficits is a well-known risk factor for various disorders and developmental defects (e.g., neural tube defects). In this review, we summarize the role of OCM disturbance and associated epigenetic aberrations in chronic alcohol-induced toxicity. In this review, we summarize the role of one-carbon metabolism (OCM) aberrations in chronic alcohol-induced toxicity. OCM is a major donor of methyl groups for methylation reactions, particularly DNA methylation critical for epigenetic regulation of gene expression. Alcohol interference with OCM and consequent reduced availability of methyl groups, improper DNA methylation, and aberrant gene expression can play a causative role in alcohol toxicity.

Factors underlying the association of body mass index with serum ALT in Chinese hypertensive adults without known hepatic diseases

OBJECTIVE

High body mass index (BMI) is considered as the most important risk factor for elevated serum alanine aminotransferase (ALT) concentration. This study examined an array of factors, including waist circumference (WC) and folate deficiency, which may mediate the association of BMI with serum ALT concentration in Chinese hypertensive adults without known hepatic diseases.

METHODS

A multicenter, cross-sectional study was carried out. A total of 378 patients with mild or moderate hypertension and without known hepatic diseases were recruited from five hospitals in Harbin, Shanghai, Beijing, Xi'an, and Nanjing.

RESULTS

Of the 360 hypertensive patients with complete data in our final analysis, 13.6% had high ALT concentrations (>40 IU/L). Factors including BMI, WC, triglyceride level, and folate concentration were associated with ALT concentration in univariate analysis. Consistently higher prevalence rates of elevated ALT were observed in subjects with lower folate concentrations (≥12 vs. <12 nmol/L, 9.9% vs. 17.8%, P=0.03), with higher BMI (≥28 vs. <28 kg/m(2), 21.5% vs. 11.4%, P=0.02) or higher WC (≥90 vs. <90 cm, 18.5% vs. 10.0%, P=0.02). However, in multivariate analysis, the association between BMI and ALT concentration disappeared (P=0.802 in males and 0.369 in females), while WC in females (P<0.001) and folate concentration (P=0.036 in males and 0.044 in females) remained as significant predictors for ALT concentration.

CONCLUSIONS

This multicenter study demonstrated that WC and low folate concentration were important factors underlying the association between BMI and ALT concentrations in Chinese hypertensive adults without known hepatic diseases.

Protective effect of S-adenosylmethionine on hepatic ischemia-reperfusion injury during hepatectomy in HCC patients with chronic HBV infection

Background

Although hepatectomy is often performed with the Pringle maneuver, the problem of hepatic ischemia-reperfusion injury (HIRI) can also be serious. Thus, the present study was designed to investigate the protective effect of S-adenosylmethionine (SAMe) on HIRI, especially for patients with hepatocellular carcinoma (HCC) associated with chronic hepatitis B virus (HBV) infection and cirrhosis.

Methods

Eighty-one HCC patients with chronic HBV infection, undergoing partial hepatectomy with inflow occlusion, were divided into three groups. In the pretreatment group (PR group, n = 26), patients were given SAMe two hours before surgery. In the post-treatment group (PO group, n = 25), patients were given SAMe six hours after surgery. And in the control group (control group, n = 30), patients received partial hepatectomy without any SAMe. All pre-, intra- and postoperative blood samples were collected to measure the plasma levels of transaminases, bilirubin and cytokines. The results were compared among the three groups.

Results

There were no statistically significant intergroup differences observed in age, gender, hepatic inflow occlusion time and the results of liver function tests. Preoperative administration of SAMe (PR group) significantly reduced the plasma levels of alanine transaminase (ALT), aspartate transferase (AST), total bilirubin (TBIL) and direct bilirubin (DBIL) as compared to the other two groups. In the PO group, TBIL and DBIL were significantly lower than in the control group. Significant differences were also seen in IL-6 and TNF-α between the PR group and the other groups. In all groups, postoperative liver reserve function in the PR group as revealed by ICGR15 (Post ICGR15) was at its best before abdominal closure. Compared to the control group, the risk of complications and the hospital stay after surgery were significantly meliorated in the PR group. Additionally, patients with cirrhosis had a more acute rate of change in ALT and AST than non-cirrhotic patients.

Conclusions

Taken together, our preliminary findings suggest that preoperative administration of SAMe is useful and safe for reducing the HIRI in partial hepatectomy, especially for HCC patients whose disease is associated with chronic HBV infection and cirrhosis.

Plasma choline, nicotine exposure, and risk of low bone mineral density and hip fracture: the Hordaland health study

Choline, obtained from diet and formed by biosynthesis, is the immediate precursor of betaine. Animal studies suggest an impact of choline on bone metabolism. We examined the associations of plasma choline and betaine with bone mineral density (BMD), the risk of hip fractures, and possible effect-modification by nicotine exposure. The Hordaland Health Study (1998 to 2000) included 7074 women and men (ages 46 to 49 or 71 to 74 years). In 5315, BMD was measured. The oldest (n = 3311) were followed for hip fractures through 2009. Risk associations were studied by logistic and Cox regression by comparing the lowest and middle tertiles with the highest, as well as trends across tertiles of plasma choline and betaine. In analyses adjusted for sex and age, participants in the lowest (odds ratio [OR] = 2.00, 95% confidence interval [CI] 1.69-2.37) and middle (OR = 1.39, CI 1.17-1.66) tertiles of plasma choline had an increased risk of low BMD (lowest quintile) (p trend < 0.001). Separate analyses for sex and age groups revealed the strongest relations in elderly women (lowest tertile: OR = 2.84, CI 1.95-4.14; middle tertile: OR = 1.80, CI 1.22-2.67, p trend < 0.001), and highest OR among those in the lowest tertile who were exposed to nicotine (OR = 4.56, CI 1.87-11.11). Low plasma choline was also associated with an increased risk of hip fracture in elderly women and men (lowest tertile: hazard ratio [HR] = 1.45, CI 1.08-1.94; middle tertile: HR = 1.13, CI 0.83-1.54, p trend = 0.012). In elderly women, the HR for hip fracture was 1.90 (CI 1.32-2.73) and 1.36 (CI 0.92-1.99) (p trend < 0.001) for lowest and middle tertiles of choline, and the highest HR was found among women in the lowest tertile exposed to nicotine (HR = 2.68, CI 1.16-6.19). Plasma betaine was not related to BMD or hip fracture. Low plasma choline was associated with low BMD in both sexes and increased the risk of hip fracture in elderly women. These results should motivate further studies on choline, nicotine exposure, and bone metabolism.

Synthetic gene circuit-mediated monitoring of endogenous metabolites: identification of GAL11 as a novel multicopy enhancer of s-adenosylmethionine level in yeast

Monitoring levels of key metabolites in living cells comprises a critical step in various investigations. The simplest approach to this goal is a fluorescent reporter gene using an endogenous promoter responsive to the metabolite. However, such a promoter is often not identified or even present in the species of interest. An alternative can be a synthetic gene circuit based on a heterologous pair consisting of a promoter and a transcription factor known to respond to the metabolite. We exploited the met operator and MetJ repressor of Escherichia coli, the interaction between which depends on S-adenosylmethionine (SAM), to construct synthetic gene circuits that report SAM levels in Saccharomyces cerevisiae. Using a dual-input circuit that outputs selection marker genes in a doxycycline-tunable manner, we screened a genomic library to identify GAL11 as a novel multicopy enhancer of SAM levels. These results demonstrate the potential and utility of synthetic gene circuit-mediated metabolite monitoring.

Alcoholic liver disease patients treated with S-adenosyl-L-methionine: an in-depth look at liver morphologic data comparing pre and post treatment liver biopsies

BACKGROUND

The objective of this study is to assess if there were any changes in liver biopsies after treatment with S-adenosyl-L-methionine(SAMe) in alcoholic liver disease patients.

METHODS

Liver biopsies of 14 patients were randomized for SAMe treatment at week 0 (biopsy #1) and at 24 weeks (biopsy #2). Patients received 1.2g of SAMe or placebo by mouth daily and stopped alcohol intake. Biopsies were semi-quantitatively scored for: steatosis, inflammation, necrosis, fibrosis, apoptosis by TUNEL stain, percent fibrosis per square field, smooth muscle actin stain, Kupffer cells, polymorphonuclear leukocytes, lipogranules, lymphocytes, balloon cell formation, Mallory-Denk bodies, and duct metaplasia.

RESULTS

Comparing treatment arm to placebo arm, no significant difference was found between biopsy #1 and biopsy #2. However, when both study arms were grouped together, there was decrease in smooth muscle actin stain, where the P-value=0.027.

CONCLUSION

Treatment with SAMe did not show a statistically significant difference in the characteristics studied. However, when both the treatment and placebo arm data were grouped together to increase the n and power, there was a decrease in the smooth muscle actin stain, reflecting a decrease in stellate cells activation, likely due to the alcohol abstinence. This study suggests that it may not be beneficial to wait for more definitive treatment, like liver transplant in alcoholic liver disease patients, since the liver tissue remained largely with the same degree of pathology six months out, regardless of treatment.

Betaine attenuates lysophosphatidylcholine-mediated adhesion molecules in aged rat aorta: modulation of the nuclear factor-κB pathway

We previously reported that lysophosphatidylcholine (LPC) is a mediator of endothelial dysfunction in the expression of adhesion molecules (AMs) during aging. This study aimed at investigating the effects of betaine on LPC-related expression of AMs and the molecular modulation of nuclear factor-κB (NF-κB) activation in the aorta of aged rats and rat endothelial YPEN-1 cells. The experiment was performed on young (7 months) and old (21 months) rats; 2 groups of old rats were fed betaine (3 or 6 mg · kg(-1) · day(-1) for 10 days). Betaine inhibited the expression of LPC-related AMs in the serum and tissue of aged rats, without affecting the elevated levels of serum LPC. Betaine also prevented the generation of reactive species, thereby maintaining the redox status via the enhancement of the thiol status during aging. Furthermore, betaine attenuated NF-κB activation via the dephosphorylation of IκB kinase (IKK) and mitogen-activated protein kinases (MAPKs) in aged aorta and LPC-treated YPEN-1 cells. Thus, betaine suppressed the LPC-related AM expression associated with NF-κB activation via the upregulation of IKK/MAPKs. Our findings provide insights into the prevention of vascular disorders and the development of interventions based on natural compounds, such as betaine.

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.

S-adenosylmethionine (SAMe) therapy in liver disease: a review of current evidence and clinical utility

S-adenosyl-L-methionine (SAMe; AdoMet) is an important, metabolically pleiotropic molecule that participates in multiple cellular reactions as the precursor for the synthesis of glutathione and principle methyl donor required for methylation of nucleic acids, phospholipids, histones, biogenic amines, and proteins. SAMe synthesis is depressed in chronic liver disease and so there has been considerable interest in the utility of SAMe to ameliorate disease severity. Despite encouraging pre-clinical data confirming that SAMe depletion can exacerbate liver injury and supporting a hepatoprotective role for SAMe therapy, to date no large, high-quality randomised clinical trials have been performed that establish clinical utility in specific disease states. Here, we offer an in-depth review of the published scientific literature relating to the physiological and pathophysiological roles of SAMe and its therapeutic use in liver disease, critically assessing implications for clinical practice and offering recommendations for further research.

Herbal products: benefits, limits, and applications in chronic liver disease

Complementary and alternative medicine soughts and encompasses a wide range of approaches; its use begun in ancient China at the time of Xia dynasty and in India during the Vedic period, but thanks to its long-lasting curative effect, easy availability, natural way of healing, and poor side-effects it is gaining importance throughout the world in clinical practice. We conducted a review describing the effects and the limits of using herbal products in chronic liver disease, focusing our attention on those most known, such as quercetin or curcumin. We tried to describe their pharmacokinetics, biological properties, and their beneficial effects (as antioxidant role) in metabolic, alcoholic, and viral hepatitis (considering that oxidative stress is the common pathway of chronic liver diseases of different etiology). The main limit of applicability of CAM comes from the lacking of randomized, placebo-controlled clinical trials giving a real proof of efficacy of those products, so that anecdotal success and personal experience are frequently the driving force for acceptance of CAM in the population.

Early changes in the liver-soluble proteome from mice fed a nonalcoholic steatohepatitis inducing diet

Despite the increasing incidence of nonalcoholic steatohepatitis (NASH) with the rise in lifestyle-related diseases such as the metabolic syndrome, little is known about the changes in the liver proteome that precede the onset of inflammation and fibrosis. Here, we investigated early changes in the liver-soluble proteome of female C57BL/6N mice fed an NASH-inducing diet by 2D-DIGE and nano-HPLC-MS/MS. In parallel, histology and measurements of hepatic content of triglycerides, cholesterol and intermediates of the methionine cycle were performed. Hepatic steatosis manifested itself after 2 days of feeding, albeit significant changes in the liver-soluble proteome were not evident before day 10 in the absence of inflammatory or fibrotic signs. Proteomic alterations affected mainly energy and amino acid metabolism, detoxification processes, urea cycle, and the one-carbon/S-adenosylmethionine pathways. Additionally, intermediates of relevant affected pathways were quantified from liver tissue, confirming the findings from the proteomic analysis.

Reduced susceptibility of DNA methyltransferase 1 hypomorphic (Dnmt1N/+) mice to hepatic steatosis upon feeding liquid alcohol diet

BACKGROUND

Methylation at C-5 (5-mdC) of CpG base pairs, the most abundant epigenetic modification of DNA, is catalyzed by 3 essential DNA methyltransferases (Dnmt1, Dnmt3a and Dnmt3b). Aberrations in DNA methylation and Dnmts are linked to different diseases including cancer. However, their role in alcoholic liver disease (ALD) has not been elucidated.

METHODOLOGY/PRINCIPAL FINDINGS

Dnmt1 wild type (Dnmt1(+/+)) and hypomorphic (Dnmt1(N/+)) male mice that express reduced level of Dnmt1 were fed Lieber-DeCarli liquid diet containing ethanol for 6 weeks. Control mice were pair-fed calorie-matched alcohol-free liquid diet, and Dnmtase activity, 5-mdC content, gene expression profile and liver histopathology were evaluated. Ethanol feeding caused pronounced decrease in hepatic Dnmtase activity in Dnmt1(+/+) mice due to decrease in Dnmt1 and Dnmt3b protein levels and upregulation of miR-148 and miR-152 that target both Dnmt1 and Dnmt3b. Microarray and qPCR analysis showed that the genes involved in lipid, xenobiotic and glutathione metabolism, mitochondrial function and cell proliferation were dysregulated in the wild type mice fed alcohol. Surprisingly, Dnmt1(N/+) mice were less susceptible to alcoholic steatosis compared to Dnmt1(+/+) mice. Expression of several key genes involved in alcohol (Aldh3b1), lipid (Ppara, Lepr, Vldlr, Agpat9) and xenobiotic (Cyp39a1) metabolism, and oxidative stress (Mt-1, Fmo3) were significantly (P<0.05) altered in Dnmt1(N/+) mice relative to the wild type mice fed alcohol diet. However, CpG islands encompassing the promoter regions of Agpat9, Lepr, Mt1 and Ppara were methylation-free in both genotypes irrespective of the diet, suggesting that promoter methylation does not regulate their expression. Similarly, 5-mdC content of the liver genome, as measured by LC-MS/MS analysis, was not affected by alcohol diet in the wild type or hypomorphic mice.

CONCLUSIONS/SIGNIFICANCE

Although feeding alcohol diet reduced Dnmtase activity, the loss of one copy of Dnmt1 protected mice from alcoholic hepatosteatosis by dysregulating genes involved in lipid metabolism and oxidative stress.

Proteasome inhibitor treatment reduced fatty acid, triacylglycerol and cholesterol synthesis

In the present study, the beneficial effects of proteasome inhibitor treatment in reducing ethanol-induced steatosis were investigated. A microarray analysis was performed on the liver of rats injected with PS-341 (Bortezomib, Velcade), and the results showed that proteasome inhibitor treatment significantly reduced the mRNA expression of SREBP-1c, and the downstream lipogenic enzymes, such as fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC), which catalyzes the carboxylation of acetyl-CoA to malonyl-CoA, the rate-limiting step in fatty acid synthesis. ELOVL6, which is responsible for fatty acids long chain elongation, was also significantly downregulated by proteasome inhibitor treatment. Moreover, PS-341 administration significantly reduced the expression of acyl-glycerol-3-phosphate acyltransferase (AGPAT), and diacylglycerol acyltransferase (DGAT), enzyme involved in triacylglycerol (TAG) synthesis. Finally, PS-341 was found to downregulate the enzyme 3-hydroxy-3-methylglutaryl-CoenzymeA synthase (HMG-CoA synthase) that is responsible for cholesterol synthesis. Proteasome inhibitor was also found to play a role in intestinal lipid adsorption because apolipoproteins A (apoA-I, apoAII, apoA-IV and ApoCIII) were downregulated by proteasome inhibitor treatment, especially ApoA-II that is known to be a marker of alcohol consumption. Proteasome inhibitor treatment also decreased apobec-1 complementation factor (ACF) leading to lower level of editing and production of ApoB protein. Moreover apolipoprotein C-III, a major component of chylomicrons was significantly downregulated. However, lipoprotein lipase (Lpl) and High density lipoprotein binding protein (Hdlbp) mRNA levels were increased by proteasome inhibitor treatment. These results suggested that proteasome inhibitor treatment could be used to reduce the alcohol-enhanced lipogenesis and alcohol-induced liver steatosis. A morphologic analysis, performed on the liver of rats fed ethanol for one month and treated with PS-341, showed that proteasome inhibitor treatment significantly decreased ethanol-induced liver steatosis. SREBP-1c, FAS and ACC were increased by ethanol feeding alone, but were significantly decreased when proteasome inhibitor was administered to rats fed ethanol. Our results also show that both mRNA and protein levels of these lipogenic enzymes, up regulated by ethanol, were then downregulated when proteasome inhibitor was administered to rats fed ethanol. It was also confirmed that alcohol feeding caused an increase in AGPAT and DGAT, which was prevented by proteasome inhibitor treatment of the animal fed ethanol. Chronic alcohol feeding did not affect the gene expression of HMG-CoA synthase. However, PS341 administration significantly reduced the HMG-CoA synthase mRNA levels, confirming the results obtained with the microarray analysis. C/EBP transcription factors alpha (CCAAT/enhancer-binding protein alpha) has been shown to positively regulate SREBP-1c mRNA expression, thus regulating lipogenesis. Proteasome inhibition caused a decrease in C/EBP alpha mRNA expression, indicating that C/EBP downregulation may be the mechanism by which proteasome inhibitor treatment reduced lipogenesis. In conclusion, our results indicate that proteasome activity is not only involved in downregulating fatty acid synthesis and triacylglycerol synthesis, but also cholesterol synthesis and intestinal lipid adsorption. Proteasome inhibitor, administrated at a non-toxic low dose, played a beneficial role in reducing lipogenesis caused by chronic ethanol feeding and these beneficial effects are obtained because of the specificity and reversibility of the proteasome inhibitor used.

Predictors of global methylation levels in blood DNA of healthy subjects: a combined analysis

BACKGROUND

Estimates of global DNA methylation from repetitive DNA elements, such as Alu and LINE-1, have been increasingly used in epidemiological investigations because of their relative low-cost, high-throughput and quantitative results. Nevertheless, determinants of these methylation measures in healthy individuals are still largely unknown. The aim of this study was to examine whether age, gender, smoking habits, alcohol drinking and body mass index (BMI) are associated with Alu or LINE-1 methylation levels in blood leucocyte DNA of healthy individuals.

METHODS

Individual data from five studies including a total of 1465 healthy subjects were combined. DNA methylation was quantified by PCR-pyrosequencing.

RESULTS

Age [β = -0.011% of 5-methyl-cytosine (%5 mC)/year, 95% confidence interval (CI) -0.020 to -0.001%5 mC/year] and alcohol drinking (β = -0.214, 95% CI -0.415 to -0.013) were inversely associated with Alu methylation. Compared with females, males had lower Alu methylation (β = -0.385, 95% CI -0.665 to -0.104) and higher LINE-1 methylation (β = 0.796, 95% CI 0.261 to 1.330). No associations were found with smoking or BMI. Percent neutrophils and lymphocytes in blood counts exhibited a positive (β = 0.036, 95% CI 0.010 to 0.061) and negative (β = -0.038, 95% CI -0.065 to -0.012) association with LINE-1 methylation, respectively.

CONCLUSIONS

Global methylation measures in blood DNA vary in relation with certain host and lifestyle characteristics, including age, gender, alcohol drinking and white blood cell counts. These findings need to be considered in designing epidemiological investigations aimed at identifying associations between DNA methylation and health outcomes.

Alcohol intake and folate antagonism via CYP2E1 and ALDH1: effects on oral carcinogenesis

The interaction of folate and alcohol consumption has been shown to have an antagonistic effect on the risk of oral cancer. Studies have demonstrated that increased intake of folate decreases the risk of oral cancer, while greater alcohol consumption has an opposite effect. However, what is poorly understood is the biological interaction of these two dietary factors in relation to carcinogenesis. We hypothesize that cytochrome P450 2E1 (CYP2E1) and the family of aldehyde dehydrogenase 1 (ALDH1) enzymes may play a causal role in the occurrence of oral cancer. Chronic and high alcohol use has been implicated in the induction of CYP2E1, which oxidizes ethanol to acetaldehyde. Acetaldehyde is a known carcinogen. As the first metabolite of ethanol, it has been shown to interfere with DNA methylation, synthesis and repair, as well as bind to protein and DNA to form stable adducts, which lead to the eventual formation of damaged DNA and cell proliferation. Studies using liver cells have demonstrated that S-adenosyl methionine (SAM), which is a product of folate metabolism, regulates the expression and catalytic activity of CYP2E1. Our first hypothesis is that as increased levels of folate lead to higher concentrations of SAM, SAM antagonizes the expression of CYP2E1, which results in decreased conversion of ethanol into acetaldehyde. Thus, the lower levels of acetaldehyde may lower risk of oral cancer. There are also two enzymes within the ALDH1 family that play an important role both in ethanol metabolism and the folate one-carbon pathway. The first, ALDH1A1, converts acetaldehyde into its non-carcinogenic byproduct, acetate, as part of the second step in the ethanol metabolism pathway. The second, ALDH1L1, also known as FDH, is required for DNA nucleotide biosynthesis, and is upregulated at high concentrations of folate. ALDH1L1 appears to be a chief regulator of cellular metabolism as it is strongly downregulated at certain physiological and pathological conditions, while its upregulation can produce drastic antiproliferative effects. ALDH1 has three known response elements that regulate gene expression (NF-Y, C/EBPβ, and RARα). Our second hypothesis is that folate interacts with one of these response elements to upregulate ALDH1A1 and ALDH1L1 expression in order to decrease acetaldehyde concentrations and promote DNA stability, thereby decreasing cancer susceptibility. Conducting future metabolic and biochemical human studies in order to understand this biological mechanism will serve to support evidence from epidemiologic studies, and ultimately promote the intake of folate to at-risk populations.

Effect of folic acid intervention on ALT concentration in hypertensives without known hepatic disease: a randomized, double-blind, controlled trial

BACKGROUND/OBJECTIVES

Increasing evidence suggests that altered methionine/folate metabolism may contribute to the development of hepatic injury. We addressed the question of whether folic acid (FA) supplementation can affect serum alanine aminotransferase (ALT) level in hypertensive Chinese adults.

SUBJECTS/METHODS

A total of 480 participants with mild or moderate essential hypertension and without known hepatic disease were randomly assigned to three treatment groups: (1) enalapril only (10 mg, control group); (2) enalapril-FA tablet (10 mg enalapril combined with 0.4 mg of FA, low FA group); and (3) enalapril-FA tablet (10 mg enalapril combined with 0.8 mg of FA, high FA group), once daily for 8 weeks.

RESULTS

This report included 455 participants in the final analysis according to the principle of intention to treat. We found a significant reduction in ALT level in the high FA group (median (25th percentile, 75th percentile), -0.6 (-6.9, 2.0)IU/l, P=0.0008). Compared with the control group, the high FA group showed a significantly greater ALT-lowering response in men (median ALT ratio (ALT at week 8 to ALT at baseline; 25th percentile, 75th percentile): 0.93 (0.67, 1.06) vs 1.00 (0.91, 1.21), P=0.032), and in participants with elevated ALT (ALT>40 IU/l) at baseline. There was no difference in ALT lowering between the control and the low FA group.

CONCLUSIONS

Compared with treatment using 10 mg of enalapril alone, a daily dose of 10 mg enalapril combined with 0.8 mg of FA showed a beneficial effect on serum ALT level, particularly in men and in participants with elevated (>40 IU/l) ALT.

The role of S-adenosyl methionine in preventing FOLFOX-induced liver toxicity: a retrospective analysis in patients affected by resected colorectal cancer treated with adjuvant FOLFOX regimen

BACKGROUND

Hepatic toxicity is often related to chemotherapy agent administration, and it represents one of the principal causes of dose reduction and chemotherapy delays or discontinuation. S-Adenosyl methionine (AdoMet) supplementation is effective in the treatment of a variety of liver injuries, but it has never been evaluated in the prevention of chemotherapy-induced liver damage.

PATIENTS AND METHODS

A total of 105 patients affected by resected colorectal cancer (CRC) were enrolled. Forty-five were treated with FOLFOX IV adjuvant regimen without administering AdoMet, 60 were treated with the same regimen plus supplementation with AdoMet. Liver enzyme levels were assessed before starting the treatment and every therapy cycle. Liver toxicity, chemotherapy course delays, discontinuations and dose reductions due to liver toxicity were recorded.

RESULTS

Aspartate aminotransferase (AST) (p < 0.001), alanine transaminase (ALT) (p = 0.003), bilirubin (p = 0.04) and gamma-glutamyltransferase (γ-GT) (p = 0.002) median level at the end of adjuvant therapy were significantly lower in patients treated with Adome. Patients supplemented with AdoMet experimented a lower grade of liver toxicity (p = 0.002) and had a reduced need of course delay (p < 0.0001) and dose reduction (p = 0.031).

CONCLUSIONS

The results of our study demonstrate a protective effect of AdoMet supplementation in patients affected by resected CRC treated with FOLFOX IV adjuvant regimen.

Folic acid supplementation during early hepatocarcinogenesis: cellular and molecular effects

Folic acid (FA) supplementation during carcinogenesis is controversial. Considering the impact of liver cancer as a public health problem and mandatory FA fortification in several countries, the role of FA supplementation in hepatocarcinogenesis should be elucidated. We evaluated FA supplementation during early hepatocarcinogenesis. Rats received daily 0.08 mg (FA8 group) or 0.16 mg (FA16 group) of FA/100 g body weight or water (CO group, controls). After a 2-week treatment, animals were subjected to the "resistant hepatocyte" model of hepatocarcinogenesis (initiation with diethylnitrosamine, selection/promotion with 2-acetylaminofluorene and partial hepatectomy) and euthanized after 8 weeks of treatment. Compared to the CO group, the FA16 group presented: reduced (p < 0.05) number of persistent and increased (p < 0.05) number of remodeling glutathione S-transferase (GST-P) positive preneoplastic lesions (PNL); reduced (p < 0.05) cell proliferation in persistent GST-P positive PNL; decreased (p < 0.05) hepatic DNA damage; and a tendency (p < 0.10) for decreased c-myc expression in microdissected PNL. Regarding all these parameters, no differences (p > 0.05) were observed between CO and FA8 groups. FA-treated groups presented increased hepatic levels of S-adenosylmethionine but only FA16 group presented increased S-adenosylmethionine/S-adenosylhomocysteine ratio. No differences (p > 0.05) were observed between experimental groups regarding apoptosis in persistent and remodeling GST-P positive PNL, and global DNA methylation pattern in microdissected PNL. Altogether, the FA16 group, but not the FA8 group, presented chemopreventive activity. Reversion of PNL phenotype and inhibition of DNA damage and of c-myc expression represent relevant FA cellular and molecular effects.

Inhibition of interferon-α-induced signaling by hyperosmolarity and hydrophobic bile acids

Apart from viral conditions, host factors such as elevated bile acid concentrations are determinants of successful interferon-α (IFN-α) treatment in patients with chronic hepatitis C or B. The present study demonstrates that hydrophobic bile acids inhibit Jak1- and Tyk2-phosphorylation, which lead to blockade of STAT1-mediated IFN-α-signaling in the sodium-taurocholate cotransporting peptide (NTCP)-transfected human hepatoma cell line HepG2, resulting in a decreased mRNA and protein expression of IFN-stimulated genes such as myxovirus resistance protein A (MxA) or dsRNA-activated protein kinase (PKR). In addition, hyperosmotic stress leads to an inhibition of IFN-α-induced Jak1- and Tyk2-phosphorylation, and STAT1/STAT2-phosphorylation and gene expression. This inhibitory effect of hydrophobic bile acids or hyperosmolarity is not due to caspase-mediated cleavage or lysosomal degradation of the cognate receptors or to the generation of oxidative stress, activation of p38- or Erk-mediated MAPK pathways or phosphatase activity. Preincubation with the organic osmolyte betaine blocked the inhibitory effect of bile acids or hyperosmolarity on MxA protein expression, but had no effect on transcript levels or activation of STAT1, suggesting that betaine mediates its effects on MxA expression at a translational or post-translational level. Our findings could provide a rationale for betaine use in cholestatic HBV/HCV patients undergoing interferon therapy.

The implications of DNA methylation for toxicology: toward toxicomethylomics, the toxicology of DNA methylation

Identifying agents that have long-term deleterious impact on health but exhibit no immediate toxicity is of prime importance. It is well established that long-term toxicity of chemicals could be caused by their ability to generate changes in the DNA sequence through the process of mutagenesis. Several assays including the Ames test and its different modifications were developed to assess the mutagenic potential of chemicals (Ames, B. N., Durston, W. E., Yamasaki, E., and Lee, F. D. (1973a). Carcinogens are mutagens: a simple test system combining liver homogenates for activation and bacteria for detection. Proc. Natl. Acad. Sci. U.S.A. 70, 2281-2285; Ames, B. N., Lee, F. D., and Durston, W. E. (1973b). An improved bacterial test system for the detection and classification of mutagens and carcinogens. Proc. Natl. Acad. Sci. U.S.A. 70, 782-786). These tests have also been employed for assessing the carcinogenic potential of compounds. However, the DNA molecule contains within its chemical structure two layers of information. The DNA sequence that bears the ancestral genetic information and the pattern of distribution of covalently bound methyl groups on cytosines in DNA. DNA methylation patterns are generated by an innate program during gestation but are attuned to the environment in utero and throughout life including physical and social exposures. DNA function and health could be stably altered by exposure to environmental agents without changing the sequence, just by changing the state of DNA methylation. Our current screening tests do not detect agents that have long-range impact on the phenotype without altering the genotype. The realization that long-range damage could be caused without changing the DNA sequence has important implications on the way we assess the safety of chemicals, drugs, and food and broadens the scope of definition of toxic agents.

Betaine-homocysteine methyltransferase: human liver genotype-phenotype correlation

Betaine-homocysteine methyltransferase (BHMT) catalyzes the remethylation of homocysteine. BHMT is highly expressed in the human liver. In the liver, BHMT catalyzes up to 50% of homocysteine metabolism. Understanding the relationship between BHMT genetic polymorphisms and function might increase our understanding of the role of this reaction in homocysteine remethylation and in S-adenosylmethionine-dependent methylation. To help achieve those goals, we measured levels of BHMT enzyme activity and immunoreactive protein in 268 human hepatic surgical biopsy samples from adult subjects as well as 73 fetal hepatic tissue samples obtained at different gestational ages. BHMT protein levels were correlated significantly (p<0.001) with levels of enzyme activity in both fetal and adult tissues, but both were decreased in fetal tissue when compared with levels in the adult hepatic biopsies. To determine possible genotype-phenotype correlations, 12 tag SNPs for BHMT and the closely related BHMT2 gene were selected from SNPs observed during our own gene resequencing studies as well as from HapMap. These SNPs data were used to genotype DNA from the adult hepatic surgical biopsy samples, and genotype-phenotype association analysis was performed. Three SNPs (rs41272270, rs16876512, and rs6875201), located 28kb upstream, in the 5'-UTR and in intron 1 of BHMT, respectively, were significantly correlated with both BHMT activity (p=3.41E-8, 2.55E-9 and 2.46E-10, respectively) and protein levels (p=5.78E-5, 1.08E-5 and 6.92E-6, respectively). We also imputed 230 additional SNPs across the BHMT and BHMT2 genes, identifying an additional imputed SNP, rs7700790, that was also highly associated with hepatic BHMT enzyme activity and protein. However, none of the 3 genotyped or one imputed SNPs displayed a "shift" during electrophoretic mobility shift assays. These observations may help us to understand individual variation in the regulation of BHMT in the human liver and its possible relationship to variation in methylation.

Choline and betaine in health and disease

Choline is an essential nutrient, but is also formed by de novo synthesis. Choline and its derivatives serve as components of structural lipoproteins, blood and membrane lipids, and as a precursor of the neurotransmitter acetylcholine. Pre-and postnatal choline availability is important for neurodevelopment in rodents. Choline is oxidized to betaine that serves as an osmoregulator and is a substrate in the betaine-homocysteine methyltransferase reaction, which links choline and betaine to the folate-dependent one-carbon metabolism. Choline and betaine are important sources of one-carbon units, in particular, during folate deficiency. Choline or betaine supplementation in humans reduces concentration of total homocysteine (tHcy), and plasma betaine is a strong predictor of plasma tHcy in individuals with low plasma concentration of folate and other B vitamins (B₂, B₆, and B₁₂) in combination TT genotype of the methylenetetrahydrofolate reductase 677 C->T polymorphism. The link to one-carbon metabolism and the recent availability of food composition data have motivated studies on choline and betaine as risk factors of chronic diseases previously studied in relation to folate and homocysteine status. High intake and plasma level of choline in the mother seems to afford reduced risk of neural tube defects. Intake of choline and betaine shows no consistent relation to cancer or cardiovascular risk or risk factors, whereas an unfavorable cardiovascular risk factor profile was associated with high choline and low betaine concentrations in plasma. Thus, choline and betaine showed opposite relations with key components of metabolic syndrome, suggesting a disruption of mitochondrial choline oxidation to betaine as part of the mitochondrial dysfunction in metabolic syndrome.