Centrilobular distribution of acetaldehyde and collagen in the ethanol-fed micropig

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.

Folate, alcohol, and liver disease

Alcoholic liver disease (ALD) is typically associated with folate deficiency, which is the result of reduced dietary folate intake, intestinal malabsorption, reduced liver uptake and storage, and increased urinary folate excretion. Folate deficiency favors the progression of liver disease through mechanisms that include its effects on methionine metabolism with consequences for DNA synthesis and stability and the epigenetic regulation of gene expression involved in pathways of liver injury. This paper reviews the pathogenesis of ALD with particular focus on ethanol-induced alterations in methionine metabolism, which may act in synergy with folate deficiency to decrease antioxidant defense as well as DNA stability while regulating epigenetic mechanisms of relevant gene expressions. We also review the current evidence available on potential treatments of ALD based on correcting abnormalities in methionine metabolism and the methylation regulation of relevant gene expressions.

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.

Effects of alcohol consumption on biomarkers of oxidative damage to DNA and lipids in ethanol-fed pigs

Chronic alcohol consumption is known to result in tissue injury, particularly in the liver, and is considered a major risk factor for cancers of the upper respiratory tract. Here we assessed the oxidative effects of subchronic ethanol consumption on DNA and lipids by measuring biomarkers 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and malondialdehyde (MDA), respectively. Physiological responses of pigs (n = 4) administered ethanol in drinking water for 39 days were compared with those of water-fed pigs (n = 4). Alcoholisation resulted in serum ethanol concentration of 1.90 g L(-1) and in a moderate but significant increase in alanine aminotransferase activity, an index of liver injury. However, between the alcoholised and control groups there were no significant differences in the levels of 8-oxodG (8-oxodG per 10(6) 2'deoxyguanosine) from leucocytes (2.52 ± 0.42 Vs 2.39 ± 0.34) or from target organs, liver, cardia and oesophagus. Serum MDA levels were also similar in ethanol-fed pigs (0.33 ± 0.04 μM) and controls (0.28 ± 0.03 μM). Interestingly, levels of 8-oxodG in cardia were positively correlated with those in oesophagus (Spearman correlation coefficient R = 1, P < 0.0001). Our results suggest that alcohol consumption may not cause oxidative damage to DNA and lipids as measured by 8-oxodG and MDA, respectively. The duration of alcoholisation and the potential alcohol-induced nutritional deficiency may be critical determinants of ethanol toxicity. Relevant biomarkers, such as factors involved in sensitization to ethanol-induced oxidative stress are required to better elucidate the relationship between alcohol consumption, oxidative stress and carcinogenesis.

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.

Alcoholic liver disease: pathogenesis and new targets for therapy

Alcoholic liver disease (ALD) is a major cause of morbidity and mortality worldwide. The spectrum of disease ranges from fatty liver to hepatic inflammation, necrosis, progressive fibrosis and hepatocellular carcinoma. In developed countries, ALD is a major cause of end-stage liver disease that requires transplantation. The most effective therapy for ALD is alcohol abstinence. However, for patients with severe forms of ALD (that is, alcoholic hepatitis) and for those who do not achieve abstinence from alcohol, targeted therapies are urgently needed. The development of new drugs for ALD is hampered by the scarcity of studies and the drawbacks of existing animal models, which do not reflect all the features of the human disease. However, translational research using liver samples from patients with ALD has identified new potential therapeutic targets, such as CXC chemokines, osteopontin and tumor necrosis factor receptor superfamily member 12A. The pathogenetic roles of these targets, however, remain to be confirmed in animal models. This Review summarizes the epidemiology, natural history, risk factors and current knowledge of the pathogenetic mechanisms of ALD. In addition, this article provides a detailed description of the findings of these translational studies and of the animal models used to study ALD.

Laboratory models available to study alcohol-induced organ damage and immune variations: choosing the appropriate model

The morbidity and mortality resulting from alcohol-related diseases globally impose a substantive cost to society. To minimize the financial burden on society and improve the quality of life for individuals suffering from the ill effects of alcohol abuse, substantial research in the alcohol field is focused on understanding the mechanisms by which alcohol-related diseases develop and progress. Since ethical concerns and inherent difficulties limit the amount of alcohol abuse research that can be performed in humans, most studies are performed in laboratory animals. This article summarizes the various laboratory models of alcohol abuse that are currently available and are used to study the mechanisms by which alcohol abuse induces organ damage and immune defects. The strengths and weaknesses of each of the models are discussed. Integrated into the review are the presentations that were made in the symposium "Methods of Ethanol Application in Alcohol Model-How Long is Long Enough" at the joint 2008 Research Society on Alcoholism (RSA) and International Society for Biomedical Research on Alcoholism (ISBRA) meeting, Washington, DC, emphasizing the importance not only of selecting the most appropriate laboratory alcohol model to address the specific goals of a project but also of ensuring that the findings can be extrapolated to alcohol-induced diseases in humans.

Epigenetic regulation of hepatic endoplasmic reticulum stress pathways in the ethanol-fed cystathionine beta synthase-deficient mouse

We tested the hypothesis that the pathogenesis of alcoholic liver injury is mediated by epigenetic changes in regulatory genes that result from the induction of aberrant methionine metabolism by ethanol feeding. Five-month-old cystathionine beta synthase heterozygous and wild-type C57BL/6J littermate mice were fed liquid control or ethanol diets by intragastric infusion for 4 weeks. Both ethanol-fed groups showed typical histopathology of alcoholic steatohepatitis, with reduction in liver S-adenosylmethionine (SAM), elevation in liver S-adenosylhomocysteine (SAH), and reduction in the SAM/SAH ratio with interactions of ethanol and genotype effects. Hepatic endoplasmic reticulum stress signals including glucose-regulated protein-78 (GRP78), activating transcription factor 4, growth arrest and DNA damage-inducible gene 153 (GADD153), caspase 12, and transcription factor sterol response element binding protein-1c (SREBP-1c) were up-regulated in ethanol-fed mice with genotype interactions and negative correlations with the SAM/SAH ratio. Immunohistochemical staining showed reduction in trimethylated histone H3 lysine-9 (3meH3K9) protein levels in centrilobular regions in both ethanol groups, with no changes in trimethylated histone H3 lysine-4 levels. The chromatin immunoprecipitation assay revealed a decrease in levels of suppressor chromatin marker 3meH3K9 in the promoter regions of GRP78, SREBP-1c, and GADD153 in ethanol-treated heterozygous cystathionine beta synthase mice. The messenger RNA expression of the histone H3K9 methyltransferase EHMT2 (G9a) was selectively decreased in ethanol-fed mice.

CONCLUSION

The pathogenesis of alcoholic steatohepatitis is mediated in part through the effects of altered methionine metabolism on epigenetic regulation of pathways of endoplasmic reticulum stress relating to apoptosis and lipogenesis.

Quantitative lipid metabolomic changes in alcoholic micropigs with fatty liver disease

BACKGROUND

Chronic ethanol consumption coupled with folate deficiency leads to rapid liver fat accumulation and progression to alcoholic steatohepatitis (ASH). However, the specific effects of alcohol on key liver lipid metabolic pathways involved in fat accumulation are unknown. It is unclear whether lipid synthesis, lipid export, or a combination of both is contributing to hepatic steatosis in ASH.

METHODS

In this study we estimated the flux of fatty acids (FA) through the stearoyl-CoA desaturase (SCD), phosphatidylethanolamine-N-methyltransferase (PEMT), and FA elongation pathways in relation to liver triacylglycerol (TG) content in Yucatan micropigs fed a 40% ethanol folate-deficient diet with or without supplementation with S-adenosyl methionine (SAM) compared with controls. Flux through the SCD and PEMT pathways was used to assess the contribution of lipid synthesis and lipid export respectively on the accumulation of fat in the liver. Liver FA composition within TG, cholesterol ester (CE), phosphatidylethanolamine, and phosphatidylcholine classes was quantified by gas chromatography.

RESULTS

Alcoholic pigs had increased liver TG content relative to controls, accompanied by increased flux through the SCD pathway as indicated by increases in the ratios of 16:1n7 to 16:0 and 18:1n9 to 18:0. Conversely, flux through the elongation and PEMT pathways was suppressed by alcohol, as indicated by multiple metabolite ratios. SAM supplementation attenuated the TG accumulation associated with alcohol.

CONCLUSIONS

These data provide an in vivo examination of liver lipid metabolic pathways confirming that both increased de novo lipogenesis (e.g., lipid synthesis) and altered phospholipid metabolism (e.g., lipid export) contribute to the excessive accumulation of lipids in liver affected by ASH.

S-adenosylmethionine attenuates oxidative liver injury in micropigs fed ethanol with a folate-deficient diet

BACKGROUND

To demonstrate a causative role for abnormal methionine metabolism in the pathogenesis of alcoholic steatohepatitis (ASH), we measured the preventive effects of supplementing folate deficient and ethanol containing diets in the micropig 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, or with ethanol supplemented with SAM at 0.4 g/1000 kcal for 14 weeks. Histopathology, markers of liver injury, and regulatory enzymes were measured in terminal liver samples.

RESULTS

Among the ethanol group, livers showed hepatocellular necrosis together with increased levels of S-adenosylhomocysteine (SAH) and reduced levels of SAM and its ratio to SAH and glutathione (GSH), together with increased malondialdehyde plus hydroxynonenol (MDA + HNE) and nitrotyrosine (NT), transcripts and protein levels of cytochrome P4502E1 (CYP2E1), activity of NADPH oxidase, and activity and protein levels of inducible nitric oxide (iNOS). These findings were attenuated partially or completely to control levels by SAM supplementation of the ethanol diet.

CONCLUSIONS

The present results indicate that SAM supplementation attenuates ethanol induced liver injury through its effects on the expressions and activities of oxidative stress pathways, and are consistent with the concept that the pathogenesis of oxidative liver injury is regulated in part through altered hepatic methionine metabolism.

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.

Chronic ethanol perturbs testicular folate metabolism and dietary folate deficiency reduces sex hormone levels in the Yucatan micropig

Although alcoholism causes changes in hepatic folate metabolism that are aggravated by folate deficiency, male reproductive effects have never been studied. We evaluated changes in folate metabolism in the male reproductive system following chronic ethanol consumption and folate deficiency. Twenty-four juvenile micropigs received folate-sufficient (FS) or folate-depleted (FD) diets or the same diets containing 40% of energy as ethanol (FSE or FDE) for 14 wk, and the differences between the groups were determined by ANOVA. Chronic ethanol consumption (FSE and FDE compared with FS and FD groups) reduced testis and epididymis weights, testis sperm concentrations, and total sperm counts and circulating FSH levels. Folate deficiency (FD and FDE compared with FS and FSE groups) reduced circulating testosterone, estradiol and LH levels, and also testicular 17,20-lyase and aromatase activities. There was histological evidence of testicular lesions and incomplete progression of spermatogenesis in all treated groups relative to the FS control, with the FDE group being the most affected. Chronic ethanol consumption increased testis folate concentrations and decreased testis methionine synthase activity, whereas folate deficiency reduced total testis folate levels and increased methionine synthase activity. In all pigs combined, testicular methionine synthase activity was negatively associated with circulating estradiol, LH and FSH, and 17,20-lyase activity after controlling for ethanol, folate deficiency, and their interaction. Thus, while chronic ethanol consumption primarily impairs spermatogenesis, folate deficiency reduces sex hormones, and the two treatments have opposite effects on testicular folate metabolism. Furthermore, methionine synthase may influence the hormonal regulation of spermatogenesis.

Consumption of alcohol by sows in a choice test

The domestic pig (Sus scrofa domesticus) has been proposed as an animal model for human alcoholism because pigs have been observed to consume alcohol voluntarily to a state of intoxication and to exhibit tolerance and physical dependence. However, it has not been established whether pigs can develop psychological dependence on alcohol. We hypothesised that feed-restricted, stall-housed pregnant sows fed alcohol non-voluntarily for 5 weeks would develop a preference for alcohol and retain this preference after removal of alcohol from the diet. We fed crossbred commercial sows (n=10) 280 ml of 95% ethanol mixed with 0.91 kg of feed and 720 ml of water twice daily for 5 weeks during the first trimester of pregnancy. Control sows (n=7) received dextrose in their feed as a caloric control, and water was added to give the feed a consistency similar to that of the alcohol-treated feed. Immediately before and after 5 weeks of alcohol or dextrose treatment and 3 weeks later, after termination of alcohol or dextrose treatment, we evaluated sow diet preference by comparing the amount of alcohol-supplemented, dextrose-supplemented and plain feed consumed during a 5-min choice test. Contrary to our hypothesis, there was no treatment effect on sow diet preference. Both alcohol-treated and control sows ate less of the alcohol diet than the other two diets in all choice tests. They did not discriminate between the plain and dextrose diets. We conclude that 5 weeks of non-voluntary consumption of alcohol in feed did not produce a preference for alcohol in pregnant sows, either during treatment or after withdrawal, thus providing no evidence for the development of psychological dependence on alcohol under these conditions.

Chronic ethanol feeding and folate deficiency activate hepatic endoplasmic reticulum stress pathway in micropigs

Previously, we showed that feeding micropigs ethanol with a folate-deficient diet promoted the development of hepatic injury while increasing hepatic levels of homocysteine and S-adenosylhomocysteine (SAH) and reducing the level of S-adenosylmethionine (SAM) and the SAM-to-SAH ratio. Our present goals were to evaluate mechanisms for hepatic injury using liver specimens from the same micropigs. The effects of ethanol feeding or folate-deficient diets, singly or in combination, on cytochrome P-450 2E1 (CYP2E1) and signal pathways for apoptosis and steatosis were analyzed using microarray, real-time PCR, and immunoblotting techniques. Apoptosis was increased maximally by the combination of ethanol feeding and folate deficiency and was correlated positively to liver homocysteine and SAH. Liver CYP2E1 and the endoplasmic reticulum stress signals glucose-regulated protein 78 (GRP78), caspase 12, and sterol regulatory element binding protein-1c (SREBP-1c) were each activated in pigs fed folate-deficient or ethanol diets singly or in combination. Liver mRNA levels of CYP2E1, GRP78, and SREBP-1c, and protein levels of CYP2E1, GRP78, nuclear SREBP, and activated caspase 12 each correlated positively to liver levels of SAH and/or homocysteine and negatively to the SAM-to-SAH ratio. The transcripts of the lipogenic enzymes fatty acid synthase, acetyl-CoA carboxylase, and stearoyl-CoA desaturase were elevated in the ethanol-fed groups, and each was positively correlated to liver homocysteine levels. The induction of abnormal hepatic methionine metabolism through the combination of ethanol feeding with folate deficiency is associated with the activation of CYP2E1 and enhances endoplasmic reticulum stress signals that promote steatosis and apoptosis.

Hepatic transmethylation reactions in micropigs with alcoholic liver disease

Alcoholic liver disease is associated with abnormal hepatic methionine metabolism, including increased levels of homocysteine and S-adenosylhomocysteine (SAH) and reduced levels of S-adenosylmethionine (SAM) and glutathione (GSH). The concept that abnormal methionine metabolism is involved in the pathogenesis of alcoholic liver disease was strengthened by our previous findings in a micropig model where combining dietary folate deficiency with chronic ethanol feeding produced maximal changes in these metabolites together with early onset of microscopic steatohepatitis and an eightfold increase in plasma aspartate aminotransferase. The goal of the present study was to determine potential mechanisms for abnormal levels of these methionine metabolites by analyzing the transcripts and activities of transmethylation enzymes in the livers of the same micropigs. Ethanol feeding or folate deficiency, separately or in combination, decreased transcript levels of methylenetetrahydrofolate reductase (MTHFR), methionine adenosyltransferase (MAT1A), glycine-N-methyltransferase (GNMT) and S-adenosylhomocysteine hydrolase (SAHH). Ethanol feeding alone reduced the activities of methionine synthase (MS) and MATIII and increased the activity of GNMT. Each diet, separately or in combination, decreased the activities of MTHFR and SAHH. In conclusion, the observed abnormal levels of methionine metabolites in this animal model of accelerated alcoholic liver injury can be ascribed to specific effects of ethanol with or without folate deficiency on the expressions and activities of hepatic enzymes that regulate transmethylation reactions. These novel effects on transmethylation reactions may be implicated in the pathogenesis of alcoholic liver disease.

Metabolic interactions of alcohol and folate

The goals and objectives of these studies, conducted over the past 30 y, were to determine: a) how chronic alcoholism leads to folate deficiency and b) how folate deficiency contributes to the pathogenesis of alcoholic liver disease (ALD). The intestinal absorption of folic acid was decreased in binge drinking alcoholics and, prospectively, in volunteers fed alcohol with low folate diets. Monkeys fed alcohol for 2 y developed decreased hepatic folate stores, folic acid malabsorption and decreased hepatic uptake but increased urinary excretion of labeled folic acid. Micropigs fed alcohol for 1 y developed features of ALD in association with decreased translation and activity of intestinal reduced folate carrier. Another study in ethanol-fed micropigs demonstrated abnormal hepatic methionine and DNA nucleotide imbalance and increased hepatocellular apoptosis. When alcohol feeding was combined with folate deficiency, micropigs developed typical histological features of ALD in 14 wk, together with elevated plasma homocysteine levels, reduced liver S-adenosylmethionine and glutathione and increased markers for DNA and lipid oxidation. In summary, chronic alcohol exposure impairs folate absorption by inhibiting expression of the reduced folate carrier and decreasing the hepatic uptake and renal conservation of circulating folate. At the same time, folate deficiency accelerates alcohol-induced changes in hepatic methionine metabolism while promoting enhanced oxidative liver injury and the histopathology of ALD.

Effect of Kupffer cell inactivation on ethanol-induced protein adducts in the liver

Tissue deposition of protein adducts derived from ethanol metabolism and lipid peroxidation, has been suggested to play a role in the initiation of alcoholic liver disease. The mechanisms modulating adduct formation have, however, remained unclear. We used immunohistochemical methods to examine acetaldehyde (AA) and malondialdehyde (MDA) adducts and cytochrome P4502E1 and P4503A2 expression in rats after administration of (i) an ethanol-diet (n = 6), (ii) ethanol-diet plus gadolinium chloride (GdCl(3)), a selective Kupffer cell toxicant (n = 7), or (iii) control diet (n = 6). A 4 week ethanol treatment resulted in liver steatosis, necrosis, and inflammation and deposition of protein adducts with both AA and MDA, which colocalized with areas of fatty change. The intensities (mean +/- SD) of the immunohistochemical reactions for both AA (2.50 +/- 1.23) and MDA (3.00 +/- 1.10) adducts were significantly higher in the ethanol-fed animals than in the controls (0.083 +/- 0.20) (0.16 +/- 0.25) (p <.001). GdCl(3) prevented adduct accumulation, the mean immunohistochemistry scores being 0.86 +/- 1.07 for AA and 1.64 +/- 0.63 for MDA, the former showing a more striking reduction (p <.01). The hepatic cytochrome enzymes were not different in the ethanol-fed groups with or without GdCl(3). The data indicates that Kupffer cells are involved in the generation of protein adducts with both acetaldehyde and ethanol-induced lipid peroxidation products in alcoholic liver disease.

Folate deficiency disturbs hepatic methionine metabolism and promotes liver injury in the ethanol-fed micropig

Alcoholic liver disease is associated with abnormal hepatic methionine metabolism and folate deficiency. Because folate is integral to the methionine cycle, its deficiency could promote alcoholic liver disease by enhancing ethanol-induced perturbations of hepatic methionine metabolism and DNA damage. We grouped 24 juvenile micropigs to receive folate-sufficient (FS) or folate-depleted (FD) diets or the same diets containing 40% of energy as ethanol (FSE and FDE) for 14 wk, and the significance of differences among the groups was determined by ANOVA. Plasma homocysteine levels were increased in all experimental groups from 6 wk onward and were greatest in FDE. Ethanol feeding reduced liver methionine synthase activity, S-adenosylmethionine (SAM), and glutathione, and elevated plasma malondialdehyde (MDA) and alanine transaminase. Folate deficiency decreased liver folate levels and increased global DNA hypomethylation. Ethanol feeding and folate deficiency acted together to decrease the liver SAM/S-adenosylhomocysteine (SAH) ratio and to increase liver SAH, DNA strand breaks, urinary 8-oxo-2'-deoxyguanosine [oxo(8)dG]/mg of creatinine, plasma homocysteine, and aspartate transaminase by more than 8-fold. Liver SAM correlated positively with glutathione, which correlated negatively with plasma MDA and urinary oxo(8)dG. Liver SAM/SAH correlated negatively with DNA strand breaks, which correlated with urinary oxo(8)dG. Livers from ethanol-fed animals showed increased centrilobular CYP2E1 and protein adducts with acetaldehyde and MDA. Steatohepatitis occurred in five of six pigs in FDE but not in the other groups. In summary, folate deficiency enhances perturbations in hepatic methionine metabolism and DNA damage while promoting alcoholic liver injury.

Folate deficiency, methionine metabolism, and alcoholic liver disease

Methionine metabolism is regulated by folate, and both folate deficiency and abnormal hepatic methionine metabolism are recognized features of alcoholic liver disease (ALD). Previously, histological features of ALD were induced in castrated male micropigs fed diets containing ethanol at 40% of kilocalories for 12 months, whereas in male micropigs fed the same diets for 12 months abnormal methionine metabolism and hepatocellular apoptosis developed. Folate deficiency may promote the development of ALD by accentuating abnormal methionine metabolism. Intact male micropigs received eucaloric diets that were folate sufficient, folate deficient, or each containing 40% of kilocalories as ethanol for 14 weeks. Folate deficiency alone reduced hepatic folates by one half, and ethanol feeding alone reduced methionine synthase, S-adenosylmethionine (SAM), and glutathione (GSH) levels and elevated plasma malondialdehyde (MDA) levels. The combined regimen elevated plasma homocysteine, hepatic S-adenosylhomocysteine (SAH), urinary 8-hydroxy-2-deoxyguanosine (oxy(8)dG), an index of DNA oxidation, and serum aspartate aminotransferase (AST) levels. Terminal hepatic histopathologic characteristics included typical features of steatonecrosis and focal inflammation in pigs fed the combined diet, with no changes in the other groups. Hepatic SAM levels correlated with those of GSH, whereas urinary oxy(8)dG and plasma MDA levels correlated with the SAM:SAH ratio and to hepatic GSH. The results demonstrate the linkage of abnormal methionine metabolism to products of DNA and lipid oxidation and to liver injury. The finding of steatonecrosis and focal inflammation only in the combined diet group supports the suggestion that folate deficiency promotes and folate sufficiency protects against the early onset of methionine cycle-mediated ALD.

Protein adducts in type I and type II fibre predominant muscles of the ethanol-fed rat: preferential localisation in the sarcolemmal and subsarcolemmal region

BACKGROUND

Chronic alcoholic myopathy is characterised by reduced muscle strength and structural changes including a decrease in the diameter of Type II (glycolytic, fast-twitch, anaerobic) fibres. In contrast, the Type I fibres (oxidative, slow-twitch, aerobic) are relatively protected. It is possible that adduct formation with reactive metabolites of ethanol may be a contributory process.

MATERIALS AND METHODS

We analysed skeletal muscles from rats fed nutritional-complete liquid diets containing ethanol as 35% of total dietary energy; control rats were fed the same diet in which ethanol was replaced by isocaloric glucose. Reduced-acetaldehyde, unreduced-acetaldehyde, malondialdehyde, malondialdehyde-acetaldehyde and alpha-hydroxyethyl protein-adducts in both soleus and plantaris were analysed by ELISA or immunohistochemistry with comparative studies in liver.

RESULTS

After 6 weeks, the weights of the plantaris, but not the soleus, were decreased. ELISA analyses for protein adducts showed increased amounts of unreduced-acetaldehyde adducts in soleus (P < 0.025) and plantaris (P < 0.025). Reduced-acetaldehyde, malondialdehyde, malondialdehyde-acetaldehyde and alpha-hydroxyethyl protein-adducts in both soleus and plantaris muscles from ethanol-fed rats were not significantly different from their pair-fed controls (P > 0.05). In contrast, liver from ethanol-fed rats showed significantly higher levels of unreduced-acetaldehyde (P < 0.025), reduced-acetaldehyde (P < 0.01), malondialdehyde (P < 0.01), malondialdehyde-acetaldehyde (P < 0.025) and alpha-hydroxyethyl radical (P < 0.01) protein adducts compared to pair-fed controls. Immuno-histochemical analysis using an antiserum reacting with both reduced- and unreduced-acetaldehyde adducts showed adducts were increased in soleus (P < 0.05) and plantaris (P < 0.025), confirming ELISA analysis. Adducts were located within the sarcolemmal (i.e. muscle membrane) and subsarcolemmal regions.

CONCLUSION

This is the first report of adduct formation in myopathic skeletal muscle due to chronic alcohol ingestion and suggests a role for acetaldehyde in the aetiology of alcoholic myopathy.

Cytochromes P450 2A6, 2E1, and 3A and production of protein-aldehyde adducts in the liver of patients with alcoholic and non-alcoholic liver diseases

BACKGROUND/AIMS

Interaction between CYP2E1, ethanol metabolites, and enhanced lipid peroxidation is linked to the pathogenesis of alcoholic liver disease. This study was conducted to compare the expression of various cytochrome enzymes and the appearance of aldehyde adducts in humans.

METHODS

Acetaldehyde- and lipid peroxidation-derived protein adducts and CYP2A6, 2E1, and 3A4/5 were examined immunohistochemically from liver specimens of 12 alcohol abusers with either mild (n=7) or severe (n=5) liver disease, and from nine non-drinking patients with non-alcoholic steatosis (n=4), or hepatitis (n=5).

RESULTS

Ethanol-inducible CYP2E1 was present in all alcoholic livers. While CYP2A6 in zone 3 hepatocytes was also abundant in the alcoholic patients with various degrees of liver disease, CYP3A415 was most prominent in alcoholic cirrhosis. The sites of CYP2E1 and CYP2A6 immunoreactivity co-localized with fatty deposits, and with the sites of acetaldehyde and lipid peroxidation-derived protein adducts. The CYP enzymes were also abundant in the centrilobular hepatocytes of patients with fatty liver due to obesity or diabetes.

CONCLUSIONS

Alcohol-induced liver damage is associated with a generalized induction of CYP2A6, CYP2E1 and CYP3A4 and generation of acetaldehyde and lipid peroxidation-derived protein-aldehyde adducts. However, CYP induction also occurred in patients with non-alcoholic steatosis.

Cytochrome P450 2E1 (CYP2E1)-dependent production of a 37-kDa acetaldehyde-protein adduct in the rat liver

Ethanol-inducible cytochrome P450 2E1 (CYP2E1) has been shown to be involved in the metabolism of both ethanol and acetaldehyde. Acetaldehyde, produced from ethanol metabolism, is highly reactive and can form various protein adducts. In this study, we investigated the role of CYP2E1 in the production of a 37-kDa acetaldehyde-protein adduct. Rats were pairfed an isocaloric control or an alcohol liquid diet with and without cotreatment of YH439, an inhibitor of CYP2E1 gene transcription, for 4 weeks. The soluble proteins from rat livers of each group were separated on SDS-polyacrylamide gels followed by immunoblot analysis using specific antibodies against the 37-kDa protein acetaldehyde adduct. In addition, catalytic activities of the enzymes involved in alcohol and acetaldehyde metabolism were measured and compared with the adduct level. Immunoblot analysis revealed that the 37-kDa adduct, absent in the pair-fed control, was evident in alcohol-fed rats but markedly reduced by YH439 treatment. Immunohistochemical analysis also showed that the 37-kDa adduct is predominantly localized in the pericentral region of the liver where CYP2E1 protein is mainly expressed. This staining disappeared in the pericentral region after YH439 treatment. The levels of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase isozymes were unchanged after YH439 treatment. However, the level of the 37-kDa protein adduct positively correlated with the hepatic content of P4502E1. These data indicate that the 37-kDa adduct could be produced by CYP2E1-mediated ethanol metabolism in addition to the ADH-dependent formation.

Autoimmune responses against oxidant stress and acetaldehyde-derived epitopes in human alcohol consumers

BACKGROUND

Studies in experimental animals have indicated that chronic ethanol ingestion triggers the formation of antibodies directed against proteins modified with reactive metabolites of ethanol and products of lipid peroxidation. However, the nature and prevalence of such antibodies have not been compared previously in alcoholic patients.

METHODS

Autoantibodies against adducts with acetaldehyde- (AA), malondialdehyde- (MDA), and oxidized epitopes (Ox) were examined from sera of 54 alcohol consumers with (n = 28) or without (n = 26) liver disease, and from 20 nondrinking controls.

RESULTS

Anti-AA-adduct IgA and IgG antibodies were elevated in 64% and 31% of patients with biopsy-proven alcoholic liver disease (ALD, n = 28), respectively. The IgA titers were significantly higher than those from nondrinking controls (p < 0.001), or heavy drinkers without significant liver disease (p < 0.001). Anti-MDA adduct titers (IgG) were elevated in 70% of the ALD patients. These titers were significantly higher (p < 0.001) than those from nondrinking controls, or heavy drinkers without liver disease. Antibodies (IgG) against Ox epitopes occurred in 43% of ALD patients, and the titers also were significantly higher (p < 0.05) than those from nondrinking controls. The anti-AA and anti-MDA adduct titers in ALD patients correlated significantly with the combined clinical and laboratory index (CCLI) of liver disease severity (r(s) = 0.449, p < 0.05; r(s) = 0.566, p < 0.01, respectively), the highest prevalences of anti-AA-adducts (73%) and anti-MDA-adducts (76%) occurring in ALD patients with cirrhosis.

CONCLUSIONS

The present results indicated that autoantibodies against several distinct types of protein modifications are generated in ALD patients showing an association with the severity of liver disease.

Collagen type I synthesized by pancreatic periacinar stellate cells (PSC) co-localizes with lipid peroxidation-derived aldehydes in chronic alcoholic pancreatitis

Chronic alcoholic pancreatitis (CAP) is characterized by progressive pancreatic fibrosis and loss of the acinar cell mass, but the pathogenesis of pancreatic fibrosis in the human is poorly understood. It has been recently suggested that lipid peroxidation-derived aldehydes such as 4-hydroxynonenal (HNE) are involved in tissue damage and fibrosis in other organs. The aim of this study was to evaluate the role of oxidative stress in the development of alcohol-induced pancreatic fibrosis in humans, and to assess the contribution of pancreatic periacinar stellate cells (PSC) in the in vivo synthesis of extracellular matrix components during CAP. Lipid peroxidation was evaluated in tissue specimens obtained from patients with CAP who underwent surgical procedures, by immunohistochemistry using a monoclonal antibody directed against HNE-protein adducts. Immunohistochemical determination of collagen type I, alpha-smooth muscle actin (alpha-SMA), and the beta subunit of human platelet-derived growth factor (PDGF-Rbeta) was also performed. In addition, the tissue mRNA expression of procollagen I, PDGF-Rbeta, and transforming growth factor-beta1 (TGF-beta1) was evaluated by in situ hybridization. In CAP, increased formation of HNE-protein adducts was evident in acinar cells adjacent to the interlobular connective tissue that stained positively for collagen type I. HNE staining was absent in normal pancreas. Several non-parenchymal periacinar cells (PSC) underlay the HNE-stained acinar cells. Those PSC stained positively for alpha-SMA and PDGF-Rbeta and showed active synthesis of procollagen type I by in situ expression of the specific mRNAs. The pattern of expression of PDGF-Rbeta mRNA reflected that observed in immunostaining, showing increased amounts of transcripts in PSC. TGF-beta1 mRNA expression was increased in CAP, but transcripts were found in several cell types including PSC, acinar, and ductal cells. These results indicate that significant lipid peroxidation phenomena occur in CAP and that they are associated with active synthesis of collagen by PSC.

Induction of cytochrome P450 enzymes and generation of protein-aldehyde adducts are associated with sex-dependent sensitivity to alcohol-induced liver disease in micropigs

To assess possible links between ethanol-induced oxidant stress, expression of hepatic cytochrome P450 (CYP) enzymes, and sex steroid status, we used immunohistochemical methods to compare the generation of protein adducts of acetaldehyde (AA), malondialdehyde (MDA), and 4-hydroxynonenal (4-HNE) with the amounts of CYP2E1, CYP2A, and CYP3A in the livers of castrated and noncastrated male micropigs fed ethanol for 12 months. In castrated micropigs, ethanol feeding resulted in accumulation of fat, hepatocellular necrosis, inflammation, and centrilobular fibrosis, whereas only minimal histopathology was observed in their noncastrated counterparts. CYP2A and CYP3A were more prominent in the castrated animals than in the noncastrated micropigs. Ethanol feeding increased the hepatic content of all CYP forms. The most significant increases occurred in CYP2E1 and CYP3A in the noncastrated animals and in CYP2E1 and CYP2A in the castrated animals. Ethanol-fed castrated animals also showed the greatest abundance of perivenular adducts of AA, MDA, and HNE. In the noncastrated ethanol-fed micropigs a low expression of each CYP form was associated with scant evidence of aldehyde-protein adducts. Significant correlations emerged between the levels of different CYP forms, protein adducts, and plasma levels of sex steroids. The present findings indicate that the generation of protein-aldehyde adducts is associated with the induction of several cytochrome enzymes in a sex steroid-dependent manner. It appears that the premature, juvenile, metabolic phenotype, as induced by castration, favors liver damage. The present findings should be implicated in studies on the gender differences on the adverse effects of ethanol in the liver.

Early alcoholic liver injury: formation of protein adducts with acetaldehyde and lipid peroxidation products, and expression of CYP2E1 and CYP3A

The formation of protein adducts with reactive aldehydes resulting from ethanol metabolism and lipid peroxidation has been suggested to play a role in the pathogenesis of alcoholic liver injury. To gain further insight on the contribution of such aldehydes in alcoholic liver disease, we have compared the appearance of acetaldehyde, malondialdehyde, and 4-hydroxynonenal adducts with the expression of cytochrome P-450IIE1, and cytochrome P-4503A enzymes in the liver of rats fed alcohol with a high-fat diet for 2 to 4 weeks according to the Tsukamoto-French procedure and in control rats (high-fat liquid diet or no treatment). Urine alcohol and serum aminotransferase levels were recorded, and the liver pathology was scored from 0 to 10 according to the presence of steatosis, inflammation, necrosis, and fibrosis. The ethanol treatment resulted in the accumulation of fat, mild necrosis and inflammation, and a mean liver pathology score of 3 (range: 1 to 5). Liver specimens from the ethanol-fed animals with early alcohol-induced liver injury were found to contain perivenular, hepatocellular acetaldehyde adducts. Malondialdehyde and 4-hydroxynonenal adducts were also present showing a more diffuse staining pattern with occasional sinusoidal reactions. In the control animals, a faint positive reaction for the hydroxynonenal adduct occurred in some of the animals fed the high fat diet, whereas no specific staining was observed in the livers from the animals receiving no treatment. Expression of both CYP2E1 and CYP3A correlated with the amount of protein adducts in the liver of alcohol-treated rats. Distinct CYP2E1-positive immunohistochemistry was seen in 3 of 7 of the ethanol-fed animals. In 5 of 7 of the ethanol-fed animals, the staining intensities for CYP3A markedly exceeded those obtained from the controls. The present findings indicate that acetaldehyde and lipid peroxidation-derived adducts are generated in the early phase of alcohol-induced liver disease. The formation of protein adducts appears to be accompanied by induction of both CYP2E1 and CYP3A.

An enzyme immune assay for serum anti-acetaldehyde adduct antibody using low-density lipoprotein adduct and its significance in alcoholic liver injury

An acetaldehyde (AcH) adduct was prepared using rabbit low-density lipoprotein as carrier proteins. An antibody against this adduct was raised in Watanabe heritable hyperlipidemic rabbits and cross-reacted with human low-density lipoprotein and bovine serum albumin adducts. Using this antibody, serum anti-AcH-adduct antibody levels were measured by a direct ELISA method in 56 Japanese adults (healthy adults and patients with nonalcoholic gastrointestinal diseases, alcoholic liver injury, or alcoholic pancreatitis). The antibody level (mean +/- SD) was 22 +/- 10 microg/ml in healthy adults, 22 +/- 11 microg/ml in nonalcoholic gastrointestinal diseases, and 16 +/- 13 microg/ml in alcoholic pancreatitis. These antibody levels tended to increase with the progression of alcoholic liver injury, starting from fatty liver via hepatitis to cirrhosis, 29 +/- 24 microg/ml in fatty liver, 35 +/- 29 microg/ml in alcoholic hepatitis, and 46 +/- 54 microg/ml in alcoholic cirrhosis. The antibody level in patients taking 100 g or more of ethanol per day tended to be higher, compared with those in people taking less ethanol. A follow-up observation revealed that alcohol abstinence after hospitalization raised serum anti-AcH-adduct antibody level in some patients and kept it constantly low in other patients. The immunohistochemical study using the anti-AcH-adduct antibody revealed the presence of adduct-like substance in hepatocytes of liver biopsy specimens obtained from patients with alcoholic liver disease. The results indicate that the anti-AcH-adduct antibody may be associated with the progress of alcoholic liver diseases.

Roles of oxidative stress in activation of Kupffer and Ito cells in liver fibrogenesis

An increasing body of experimental evidence is emerging to incriminate oxidative stress as a pivotal signal for liver fibrogenesis. This paper reviews the results from our studies testing this hypothesis. In the rat model of alcoholic liver disease, the importance of oxidative stress was supported by marked accentuation of liver fibrosis by dietary supplementation of iron, a pro-oxidant, and the significant correlation of the liver malondialdehyde (MDA) and 4-hydroxynonenal (4HNE) levels with the hepatic collagen accumulation. Both MDA and 4HNE adduct epitopes were detected intensely and diffusely in close association with collagen deposition. The direct cause and effect relationship between MDA/4HNE and Ito cell stimulation was indicated by the demonstration of Ito cell collagen gene induction by these aldehydes in culture. In primary cultures of rat Kupffer cells (KC), addition of antioxidants such as alpha-tocopherol acetate and succinate suppressed mRNA expression and the release of interleukin (IL)-6 and tumour necrosis factor alpha (TNF alpha). In rats with biliary fibrosis, an increase in the liver MDA level was accompanied by enhanced mRNA expression of procollagen alpha 1(I) and transforming growth factor beta 1 in Ito cells; and that of TNF alpha and IL-6 in KC. Furthermore, the gel shift assay of KC nuclear extracts showed enhanced NF-kB DNA binding activity. These results support the proposal that enhanced oxidative stress constitutes an important signal for activation of Kupffer and Ito cells in experimental liver fibrogenesis.

Prooxidant and antioxidant hepatic factors in rats chronically fed an ethanol regimen and treated with an acute dose of lindane

While acute lindane treatment and chronic ethanol feeding to rats have been associated with hepatic oxidative stress, the possible roles of these stresses in the pathogenesis of hepatic lesions reported in acute lindane intoxication and in those observed in some models of chronic alcoholism have not been established. Our previous studies in rats chronically fed ethanol regimens and then treated with a single intraperitoneal (i.p.) dose of lindane (20 mg/kg) showed that while lindane per se was invariably associated with hepatic oxidative stress, chronic ethanol feeding only produced this stress when the dietary level of vitamin E was relatively low. Chronic ethanol pretreatment did not significantly affect the lindane-associated oxidative stress, and neither chronic ethanol feeding nor acute lindane, single or in combination, produced any histologic and biochemical evidence of liver damage. In the present experiment, the acute dose of lindane was increased to 40 mg/kg, and we have studied a larger number of prooxidant and antioxidant hepatic factors. Male Wistar rats (115.5 +/- 5.4 g) were fed ad lib for 11 weeks a calorically well-balanced and nutritionally adequate basal diet, or the same basal diet plus a 32% ethanol/25% sucrose solution, also ad lib, and were then injected i.p. with a single dose of lindane or with equivalent amounts of corn oil. The results indicated that acute lindane treatment to naive rats increased practically all the prooxidant hepatic factors examined (cytochromes P450 and b5, NADPH cytochrome c reductase, NADPH oxidase), as well as the generation of microsomal superoxide radical and thiobarbituric acid reactive substances of liver homogenates, but did not modify any of the antioxidant hepatic factors studied. Conversely, the chronic administration of ethanol alone did not significantly affect the prooxidant hepatic factors but reduced some of the antioxidants (i.e., the activities of GSH-Px and the contents of alpha-tocopherol and ubiquinols 9 and 10). Although chronic ethanol pretreatment further increased the superoxide generation induced by lindane per se, it did not increase but generally reduced the effects of lindane per se on the other prooxidant factors studied. Furthermore, although acute lindane administration to ethanol-pretreated rats was associated with decreases in GSH and catalase (not affected by ethanol or lindane treatment alone), it did not substantially modify the reducing effects of ethanol feeding per se on GSH-Px, alpha-tocopherol, and ubiquinols. Once again, neither chronic ethanol feeding nor lindane treatment, single or in combination, was associated with any evidence of liver damage.

Selective reduction of delta 6 and delta 5 desaturase activities but not delta 9 desaturase in micropigs chronically fed ethanol

This study investigated the mechanism by which chronic ethanol feeding reduces arachidonate and other highly unsaturated fatty acids in pig liver phospholipids. Five micropigs were fed a diet providing 89 kcal/kg body wt for 12 mo, with ethanol and fat as 40 and 34% of energy, respectively. Five control pigs were pairfed corn starch instead of ethanol. The activities of delta 6 and delta 5 desaturases (expressed as microsomal conversion of precursor to product) in liver from ethanol-fed pigs were reduced to less than half that of controls, whereas the activity of delta 9 desaturase was unaffected in the ethanol group. delta 5 Desaturase activity showed positive correlation with the abundance of its products in liver total phospholipids and microsomes in the ethanol group, but not in the controls. Correlation between delta 6 desaturase activity and its products showed similar pattern to that of delta 5 desaturase, but did not reach statistical significance. No difference was observed between the two groups in coenzyme A concentration in the liver. These results suggest that the selective reduction of delta 6 and delta 5 desaturase activities, not the microsomal electron transport system, are directly responsible for the altered profile of liver phospholipids.

The body composition and lipid metabolic effects of long-term ethanol feeding during a high omega 6 polyunsaturated fatty acid diet in micropigs

Our previous research with miniature pigs has shown that long-term ethanol feeding with a low-fat diet decreases arachidonic acid (20:4 omega 6) levels in multiple tissues, but we did not find significant liver pathology. In this study, we investigated the effect of ethanol feeding with high dietary linoleic acid (18:2 omega 6) on tissue fatty acid (FA) profiles and body composition. Five Yucatan micropigs were fed 370 kJ (89 kcal)/kg body weight of a diet containing ethanol and fat as 40% and 34% of energy, respectively; five control pigs were pair-fed corn starch in place of ethanol. Corn oil, 61% 18:2 omega 6, supplied most of the dietary fat. Liver biopsies were performed at baseline (n = 2 per group) and at three other time points (n = 5 per group). Phospholipid (PL) FA levels were measured by thin-layer and gas chromatography. Body composition was analyzed by underwater weighing of carcasses. Body composition analysis demonstrated a marked reduction of carcass fat in the ethanol group, but no significant reduction of carcass lean weight after 12 months. In liver PLs, the ethanol group showed decreased 20:4 omega 6 and docosahexaenoic acid (22:6 omega 3) after 1 month. While the decreased 20:4 omega 6 remained constant after 1 month, 22:6 omega 3 showed a progressive decrease up to 12-months, resulting in a continuous decrease of the omega 3/omega 6 FA ratio. This slowly progressive decrease in the omega 3/omega 6 ratio in liver PLs with ethanol feeding may have enhanced the inflammatory response in the liver, contributing to liver pathology. Body composition results indicate marked wasting of energy in the ethanol group.