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

β-Carotene Increases Activity of Cytochrome P450 2E1 during Ethanol Consumption

One of the key routes through which ethanol induces oxidative stress appears to be the activation of cytochrome P450 2E1 at different levels of ethanol intake. Our aim was to determine if oral β-carotene intake had an antioxidant effect on CYP2E1 gene expression in mice that had previously consumed ethanol. C57BL/6 mice were used and distributed into: control (C), low-dose alcohol (LA), moderate-dose alcohol (MA), β-carotene (B), low-dose alcohol+β-carotene (LA + B), and moderate-dose alcohol+β-carotene (MA + B). Animals were euthanized at the end of the experiment, and liver tissue was taken from each one. CYP2E1 was measured using qPCR to detect liver damage. The relative expression level of each RNA was estimated using the comparative threshold cycle (Ct) technique (2^−ΔΔCT method) by averaging the Ct values from three replicates. The LA+B (2267 ± 0.707) and MA+B (2.307 ± 0.384) groups had the highest CYP2E1 fold change values. On the other hand, the C (1.053 ± 0.292) and LA (1.240 ± 0.163) groups had the lowest levels. These results suggest that ethanol feeding produced a fold increase in CYP2E1 protein in mice as compared to the control group. Increased CYP2E1 activity was found to support the hypothesis that β-carotene might be dangerous during ethanol exposure in animal models. Our findings imply that β-carotene can increase the hepatic damage caused by low and high doses of alcohol. Therefore, the quantity of alcohol ingested, the exposure period, the regulatory mechanisms of alcoholic liver damage, and the signaling pathways involved in the consumption of both alcohol and antioxidant must all be considered.

Vitamin Supplements as a Nutritional Strategy against Chronic Alcohol Consumption? An Updated Review

Several studies have shown that blood vitamin levels are low in alcoholic patients. In effect, alcohol use abuse is considered a chronic disease that promotes the pathogenesis of many fatal diseases, such as cancer and liver cirrhosis. The alcohol effects in the liver can be prevented by antioxidant mechanisms, which induces enzymatic as well as other nonenzymatic pathways. The effectiveness of several antioxidants has been evaluated. However, these studies have been accompanied by uncertainty as mixed results were reported. Thus, the aim of the present review article was to examine the current knowledge on vitamin deficiency and its role in chronic liver disease. Our review found that deficiencies in nutritional vitamins could develop rapidly during chronic liver disease due to diminished hepatic storage and that inadequate vitamins intake and alcohol consumption may interact to deplete vitamin levels. Numerous studies have described that vitamin supplementation could reduce hepatotoxicity. However, further studies with reference to the changes in vitamin status and the nutritional management of chronic liver disease are in demand.

Chronic Ethanol Exposure Effects on Vitamin D Levels Among Subjects with Alcohol Use Disorder

Vitamin D has been previously recognized to play important roles in human immune system and function. In the pulmonary system, vitamin D regulates the function of antimicrobial peptides, especially cathelicidin/LL-37. Human cathelicidin/LL-37 is a bactericidal, bacteriostatic, and antiviral endogenous peptide with protective immune functions. Chronic exposure to excessive alcohol has the potential to reduce levels of vitamin D (inactive vitamin D [25(OH)D3] and active vitamin D [1, 25(OH)2D3]) and leads to downregulation of cathelicidin/LL-37. Alcohol-mediated reduction of LL-37 may be partly responsible for increased incidence of more frequent and severe respiratory infections among subjects with alcohol use disorder (AUD). The objective of this study was to investigate the mechanisms by which alcohol exerts its influence on vitamin D metabolism. In addition, the aim was to establish associations between chronic alcohol exposures, levels of pulmonary vitamin D, and cathelicidin/LL-37 using broncho-alveolar lavage fluid samples of subjects with AUD and healthy controls. Findings from the experiment showed that levels of inactive vitamin D (25(OH)D3), active vitamin D (1, 25(OH)2D3), cathelicidin/LL-37, and CYP27B1 proteins were significantly reduced (P < 0.05) when compared with the matched healthy control group. However, CYP2E1 was elevated in all the samples examined. Chronic exposure to alcohol has the potential to reduce the levels of pulmonary vitamin D and results in subsequent downregulation of the antimicrobial peptide, LL-37, in the human pulmonary system.

Dietary diallyl disulfide supplementation attenuates ethanol-mediated pulmonary vitamin D speciate depletion in C57Bl/6 mice

Background

Slightly more than 5 % of the United States population heavily consumes ethanol, i.e., more than 14 drinks for men and 7 drinks for women a week. Chronic ethanol consumption can result in increased liver disease, reduced recovery from burn injury, and more frequent and severe respiratory infections. Chronic ethanol over-consumption also leads to vitamin D dysmetabolism and depletion. Vitamin D is a fat-soluble pro-hormone that regulates musculoskeletal health, cellular proliferation/differentiation, and innate and adaptive immune response.

Methods

In this study, C57BL/6 mice were fed 20 % ethanol in their water ad libitum for 7 weeks. Some mice were fed either a standard chow or a modified diet containing 0.15 μg/day of diallyl disulfide (DADS). Whole blood, lung tissue, and bronchial alveolar lavage fluid (BALF) were collected at sacrifice and analyzed for 25(OH) D₃, 1,25 (OH)₂D₃, vitamin D receptor VDR, CYP2E1, and CYP27B1 levels.

Results

Ethanol reduced 25(OH) D₃ and 1,25 (OH)₂D₃ in lung tissue and BALF on average 31 %. The largest ethanol-mediated reduction was in the 1,25 (OH)₂D₃ (42 %) measured in the BALF. Dietary supplementation of DADS restored BALF and lung tissue protein of 25(OH) D₃ and 1,25(OH)₂D₃ to control levels. Chronic ethanol consumption also resulted in tissue increases of vitamin D response (VDR) protein, Cyp2E1, and reductions in vitamin D-activating enzyme CYP27B1. All three of these effects were attenuated by dietary supplementation of DADS.

Conclusions

In conclusion, the pulmonary metabolic disturbances mediated by chronic ethanol consumption as measured by 1,25(OH)₂D₃ protein levels, epithelial lining fluid, and lung tissue can be ameliorated by dietary supplementation of DADS in C57BL/6 mice.

Transcriptomic analysis of hepatic responses to testosterone deficiency in miniature pigs fed a high-cholesterol diet

Background

Recent studies have indicated that low serum testosterone levels are associated with increased risk of developing hepatic steatosis; however, the mechanisms mediating this phenomenon have not been fully elucidated. To gain insight into the role of testosterone in modulating hepatic steatosis, we investigated the effects of testosterone on the development of hepatic steatosis in pigs fed a high-fat and high-cholesterol (HFC) diet and profiled hepatic gene expression by RNA-Seq in HFC-fed intact male pigs (IM), castrated male pigs (CM), and castrated male pigs with testosterone replacement (CMT).

Results

Serum testosterone levels were significantly decreased in CM pigs, and testosterone replacement attenuated castration-induced testosterone deficiency. CM pigs showed increased liver injury accompanied by increased hepatocellular steatosis, inflammation, and elevated serum alanine aminotransferase levels compared with IM pigs. Moreover, serum levels of total cholesterol, low-density lipoprotein cholesterol, and triglycerides were markedly increased in CM pigs. Testosterone replacement decreased serum and hepatic lipid levels and improved liver injury in CM pigs. Compared to IM and CMT pigs, CM pigs had lower serum levels of superoxide dismutase but higher levels of malondialdehyde. Gene expression analysis revealed that upregulated genes in the livers of CM pigs were mainly enriched for genes mediating immune and inflammatory responses, oxidative stress, and apoptosis. Surprisingly, the downregulated genes mainly included those that regulate metabolism-related processes, including fatty acid oxidation, steroid biosynthesis, cholesterol and bile acid metabolism, and glucose metabolism. KEGG analysis showed that metabolic pathways, fatty acid degradation, pyruvate metabolism, the tricarboxylic acid cycle, and the nuclear factor-kappaB signaling pathway were the major pathways altered in CM pigs.

Conclusions

This study demonstrated that testosterone deficiency aggravated hypercholesterolemia and hepatic steatosis in pigs fed an HFC diet and that these effects could be reversed by testosterone replacement therapy. Impaired metabolic processes, enhanced immune and inflammatory responses, oxidative stress, and apoptosis may contribute to the increased hepatic steatosis induced by testosterone deficiency and an HFC diet. These results deepened our understanding of the molecular mechanisms of testosterone deficiency-induced hepatic steatosis and provided a foundation for future investigations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1283-0) contains supplementary material, which is available to authorized users.

Cytochrome P450 2E1: its clinical aspects and a brief perspective on the current research scenario

Research on Cytochrome P450 2E1 (CYP2E1), a key enzyme in alcohol metabolism has been very well documented in literature. Besides the involvement of CYP2E1 in alcohol metabolism as illustrated through the studies discussed in the chapter, recent studies have thrown light on several other aspects of CYP2E1 i.e. its extrahepatic expression, its involvement in several diseases and pathophysiological conditions; and CYP2E1 mediated carcinogenesis and modulation of drug efficacy. Studies involving these interesting facets of CYP2E1 have been discussed in the chapter focusing on the recent observations or ongoing studies illustrating the crucial role of CYP2E1 in disease development and drug metabolism.

Dried chicory root modifies the activity and expression of porcine hepatic CYP3A but not 2C--effect of in vitro and in vivo exposure

Hepatic cytochrome P450 expression and activity are dependent on many factors, including dietary ingredients. In the present study, we investigated the in vivo and in vitro effect of chicory root on hepatic CYP3A and 2C in male pigs. Chicory feeding increased the expression of CYP3A29 mRNA but not CYP2C33. Correspondingly, CYP3A activity was increased by chicory feeding, while CYP2C activity was not affected. Additionally, the in vitro effect of chicory extract on the CYP3A activity was investigated. It was shown that CYP3A activity in the microsomes from male pigs was inhibited, but this effect was eliminated by pre-incubation. In both male and female pigs the CYP3A activity was increased in the presence of chicory after pre-incubation. Furthermore, gender-related differences in mRNA expression and activity were observed. CYP3A mRNA expression was greater in female pigs; this was not reflected on activity. For CYP2C, no difference in mRNA expression was observed, while CYP2C activity was greater in female pigs. Surprisingly, the expression of the constitutive androstane receptor, pregnane X receptor and aryl hydrocarbon receptor did not differ with feed or gender. In conclusion, chicory root modifies the expression and activity of CYP3A in vivo and in vitro, while CYP2C is not affected.

Folic acid supplementation reduces oxidative stress and hepatic toxicity in rats treated chronically with ethanol

Folate deficiency and hyperhomocysteinemia are found in most patients with alcoholic liver disease. Oxidative stress is one of the most important mechanisms contributing to homocysteine (Hcy)-induced tissue injury. However it has not been examined whether exogenous administration of folic acid attenuates oxidative stress and hepatic toxicity. The aim of this study was to investigate the in vivo effect of folic acid supplementation on oxidative stress and hepatic toxicity induced by chronic ethanol consumption. Wistar rats (n = 32) were divided into four groups and fed 0%, 12%, 36% ethanol, or 36% ethanol plus folic acid (10 mg folic acid/L) diets. After 5 weeks, chronic consumption of the 36% ethanol diet significantly increased plasma alanine transaminase (ALT) (P < 0.05) and aspartate transaminase (AST) (P < 0.05), triglycerides (TG) (P < 0.05), Hcy (P < 0.001), and low density lipoprotein conjugated dienes (CD) (P < 0.05) but decreased total radical-trapping antioxidant potential (TRAP) (P < 0.001). These changes were prevented partially by folic acid supplementation. The 12% ethanol diet had no apparent effect on most parameters. Plasma Hcy concentration was well correlated with plasma ALT (r = 0.612^**), AST (r = 0.652^*), CD (r = 0.495^*), and TRAP (r = -0.486^*). The results indicate that moderately elevated Hcy is associated with increased oxidative stress and liver injury in alcohol-fed rats, and suggests that folic acid supplementation appears to attenuate hepatic toxicity induced by chronic ethanol consumption possibly by decreasing oxidative stress.

Gender-dependent impacts of body mass index and moderate alcohol consumption on serum uric acid--an index of oxidant stress status?

Uric acid seems to be causally involved in a variety of medical disorders involving oxidative stress. Although alcohol abuse and obesity are known to increase serum uric acid, the interactions between moderate drinking, adiposity, and uric acid metabolism have remained poorly understood. We examined serum uric acid concentrations from 2062 apparently healthy volunteers (970 men, 1092 women) reporting either no alcohol (abstainers) or <40 g of ethanol consumption per day (moderate drinkers). The study population was further classified according to BMI as follows: <19 (underweight), 19-25 (normal weight), 25-30 (overweight), and >30 (obese). Serum uric acid concentrations in male moderate drinkers were significantly higher, and in females they were lower, than in the corresponding groups of abstainers. In the BMI-based subgroups, the highest concentrations were found in those who were overweight or obese. Significant two-factor interactions occurred between gender and drinking status (p<0.001) and between gender and BMI (p<0.02). Serum uric acid also correlated with indices of hepatocellular health (GGT, ALT, AST). The data indicate distinct gender-dependent impacts of alcohol consumption and BMI on serum uric acid. These findings should be applicable to the assessment of oxidative stress status and associated morbidity in alcohol consumers and individuals with excess body weight.

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.

Effect of moderate alcohol consumption on liver enzymes increases with increasing body mass index

BACKGROUND

Although both ethanol consumption and overweight alter the activities of hepatic enzymes in circulation, the differentiation of an alcohol or nonalcohol basis for such changes remains problematic. The magnitude of alterations occurring among moderate drinkers has remained obscure.

OBJECTIVE

We examined the links between moderate ethanol consumption, body mass index (BMI; in kg/m(2)), and liver enzymes.

DESIGN

Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyltransferase (GGT) were recorded from 2,164 apparently healthy participants (1,028 men, 1,136 women) reporting either no alcohol (abstainers) or <40 g ethanol consumption per day (moderate drinkers). The study population was further classified according to BMI as follows: <19 (underweight), > or =19 and <25 (normal weight), > or =25 and <30 (overweight), and > or =30 (obese).

RESULTS

Serum ALT (P < 0.05) and GGT (P < 0.001) but not AST (P = 0.805) activities in moderate drinkers were higher than those in abstainers. For all enzymes, a significant main effect was observed of increasing BMI, which was more striking in moderate drinkers than in abstainers. Tests of between-subjects effects indicated significant interactions with sex and drinking status, although not with sex and BMI.

CONCLUSIONS

The effect of moderate alcohol consumption on liver enzymes increases with increasing BMI. These findings should be considered in the clinical assessment of overweight alcohol consumers and in the definition of normal ranges for liver enzymes. These results may also help to develop new approaches for examining patients with fatty liver induced by either ethanol or adiposity.

Formation and immunological properties of aldehyde-derived protein adducts following alcohol consumption

Most ingested ethanol is eliminated from the body through oxidative metabolism in the liver. Alcohol dehydrogenase is the enzyme that is most important in the oxidation of ethanol to acetaldehyde. However, it has also been demonstrated that cytochrome P4502E1 also can contribute to this process. However, this is not the only aldehyde that is produced after chronic ethanol consumption because oxidative stress and lipid peroxidation can be induced in the liver, which results in the production of malondialdehyde and 4-hydroxy-2-nonenal. These aldehydes are highly reactive and have the ability to react with (adduct) many macromolecules to alter their structure and play a major role in the derangements of hepatic function. Therefore, the formation of these types of adducts in the liver has been proposed as key events leading to the development and/or progression of alcoholic liver disease. In this chapter, methods for the production and detection of these modified proteins will be discussed.

Sex- or gender-specific medicine in hepatology

Sex- or gender-specific medicine is an up-to-date medical science in recent medical care. Medical doctors must offer better medical care and should understand and elucidate the mechanisms underlying the sex or gender differences regarding the incidence or etiology, clinical features, and natural history or response to therapies. Sex or gender differences are frequently seen among liver diseases, such as viral hepatitis, alcoholic liver disease, non-alcoholic fatty liver disease, autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis and hepatocellular carcinoma. The mechanisms of sex or gender differences, however, are still unclear. Clinicians and basic scientists are required to cooperatively contribute to the development of sex- or gender-specific medicine to establish an accurate diagnosis and prophylaxis.

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.

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.

Additive effects of moderate drinking and obesity on serum gamma-glutamyl transferase activity

BACKGROUND

Gamma-glutamyl transferase (GGT) is a widely used index of liver induction and a marker of alcohol overconsumption. Obesity has also been suggested to elevate serum GGT activities.

OBJECTIVE

The aim was to examine the links between moderate ethanol consumption, obesity, and GGT activities.

DESIGN

GGT values were recorded from 2490 persons (1184 men and 1306 women) who reported either no alcohol use (abstainers) or 1-40 g ethanol consumption per day (moderate drinkers). The study population was additionally classified according to body mass index (BMI; in kg/m2) as follows: < 19 (underweight), > or = 19 and < 25 (normal weight), > or = 25 and < 30 (overweight), and 30 (obese).

RESULTS

Significant main effects of sex (P < 0.0001), drinking habits (P < 0.01), and BMI (P < 0.001) on serum GGT activities were observed. The values were higher in the men than in the women and higher in those with higher BMIs. The highest activities were found to occur in persons with moderate drinking combined with overweight or obesity. A significant positive correlation between GGT and BMI (P < 0.0001) was observed, which was stronger for the men (r = 0.24) than for the women (r = 0.15, P < 0.05 for the difference between correlations).

CONCLUSION

The data indicate that serum GGT activities may respond to moderate drinking and overweight in an additive manner; this should be considered in the clinical use of GGT measurements and when defining normal GGT values in health care.

PROTEIN ADDUCT SPECIES IN MUSCLE AND LIVER OF RATS FOLLOWING ACUTE ETHANOL ADMINISTRATION

AIMS

Previous immunohistochemical studies have shown that the post-translational formation of aldehyde-protein adducts may be an important process in the aetiology of alcohol-induced muscle disease. However, other studies have shown that in a variety of tissues, alcohol induces the formation of various other adduct species, including hybrid acetaldehyde-malondialdehyde-protein adducts and adducts with free radicals themselves, e.g. hydroxyethyl radical (HER)-protein adducts. Furthermore, acetaldehyde-protein adducts may be formed in reducing or non-reducing environments resulting in distinct molecular entities, each with unique features of stability and immunogenicity. Some in vitro studies have also suggested that unreduced adducts may be converted to reduced adducts in situ. Our objective was to test the hypothesis that in muscle a variety of different adduct species are formed after acute alcohol exposure and that unreduced adducts predominate.

METHODS

Rabbit polyclonal antibodies were raised against unreduced and reduced aldehydes and the HER-protein adducts. These were used to assay different adduct species in soleus (type I fibre-predominant) and plantaris (type II fibre-predominant) muscles and liver in four groups of rats administered acutely with either [A] saline (control); [B] cyanamide (an aldehyde dehydrogenase inhibitor); [C] ethanol; [D] cyanamide+ethanol.

RESULTS

Amounts of unreduced acetaldehyde and malondialdehyde adducts were increased in both muscles of alcohol-dosed rats. However there was no increase in the amounts of reduced acetaldehyde adducts, as detected by both the rabbit polyclonal antibody and the RT1.1 mouse monoclonal antibody. Furthermore, there was no detectable increase in malondialdehyde-acetaldehyde and HER-protein adducts. Similar results were obtained in the liver.

CONCLUSIONS

Adducts formed in skeletal muscle and liver of rats exposed acutely to ethanol are mainly unreduced acetaldehyde and malondialdehyde species.

Warfarin Maintenance Dosing Patterns in Clinical Practice

BACKGROUND

The use of anticoagulant therapy is expanding among the elderly population, in part because of the increasing prevalence of atrial fibrillation. Published data describing the warfarin maintenance dose requirements for this age group are limited. Because warfarin therapy is often initiated in the outpatient setting where significant barriers to daily monitoring exist for this patient population, a better understanding of the factors that predict lower dose requirements may reduce the risk of unanticipated over-anticoagulation and hemorrhage.

OBJECTIVE

To define the effects of age and gender on the warfarin maintenance dose among ambulatory adult patients with an international normalized ratio target between 2.0 and 3.0.

DESIGN

Prospective cohort study and retrospective cohort secondary data source.

SETTING

One hundred one community-based physician practices with dedicated warfarin management systems and an academic medical center anticoagulation clinic.

PATIENTS

A total of 4,616 patients comprised the prospective cohort, and 7,586 patients comprised the retrospective cohort. Of the 12,202 patients, 2,359 were > or = 80 years of age.

MEASUREMENTS

Median weekly and daily maintenance warfarin dose.

RESULTS

The warfarin dose was inversely related to age and was strongly associated with gender. The median weekly dose ranged from 45 mg (6.4 mg/d) for men who were < 50 years of age to 22 mg (3.1 mg/d) for women > or = 80 years of age. The weekly dose declined by 0.4 mg/yr (95% confidence interval [CI], 0.37 to 0.44; p < 0.001) and women required 4.5 mg less per week than men (95% CI, 3.8 to 5.3; p < 0.001). Among patients who were > 70 years of age, the often-suggested initiation dose of 5 mg/d will be excessive for 82% of women and 65% of men.

CONCLUSIONS

Warfarin dose requirements decrease greatly with age. Older women require the lowest warfarin doses. These observations suggest that, when warfarin is being initiated, the commonly employed empiric starting dose of 5 mg/d will lead to over-anticoagulation for the majority of patients in the geriatric age group; lower initiation and maintenance doses should be considered for the elderly.

Reactions of 4-hydroxynonenal with proteins and cellular targets

Peroxidative degradation of lipids yields the aldehyde 4-hydroxy-2-nonenal (4HNE) as a major product. The lipid aldehyde is an electrophile, and reactivity of 4HNE toward protein nucleophiles (i.e., Cys, His, and Lys) has been characterized. Through the use of purified enzymes and isolated cells, various pathways for biotransformation of the lipid aldehyde have been identified and include enzyme-mediated oxidation, reduction, and glutathione conjugation. Uncontrolled oxidative stress can yield excessive lipid peroxidation and 4HNE generation, however, and overwhelm these cellular defenses. Indeed, in vitro and in vivo production of 4HNE in response to pro-oxidant exposure has been demonstrated using antibodies to protein adducts of the lipid aldehyde. Recent evidence suggests a role for protein modification by 4HNE in the pathogenesis of several diseases (e.g., alcohol-induced liver disease); however, the precise mechanism(s) is currently unknown but likely results from adduction of proteins involved in cellular homeostasis or biological signaling.

Transcription profiling reveals mitochondrial, ubiquitin and signaling systems abnormalities in postmortem brains from subjects with a history of alcohol abuse or dependence

Alcohol abuse is a common human disorder with high rate of comorbidity with other psychiatric disorders. To identify candidate mechanisms for alcohol abuse, the expression of 12,626 genes was measured in postmortem temporal cortex from 11 subjects with a history of alcohol abuse or dependence, with or without other psychiatric diagnoses and compared pairwise with the expression in 11 nonalcoholic subjects matched for the other psychiatric diagnoses and demographics. Genes were defined to have altered expression in alcohol abuse if: 1) the gene showed decreased expression in at least 10 of 11 subjects with alcohol abuse, or showed increased expression in at least 10 of 11 subjects with this diagnosis compared to matched non-abusers (P < 0.007, chi(2)test); or 2) the difference in the mean abuser/non-abuser ratio for the gene from value of 1.0 was significant at P < 0.05 (one sample t-test). In subjects with a history of alcohol abuse or dependence, 163 genes were changed significantly. The most abundant and consistent changes were in gene families encoding mitochondrial proteins, the ubiquitin system, and signal transduction. These alterations indicate disturbances in energy metabolism and multiple signaling mechanisms in the temporal cortex of subjects with a history of alcohol abuse or dependence. We hypothesize that these mechanisms may be related to alcohol abuse traits or long-term effects of alcohol.

Immunohistochemical characterization of hepatic malondialdehyde and 4-hydroxynonenal modified proteins during early stages of ethanol-induced liver injury

BACKGROUND

Chronic ethanol consumption is associated with hepatic lipid peroxidation and the deposition or retention of aldehyde-adducted proteins postulated to be involved in alcohol-induced liver injury. The purpose of this study was to characterize hepatocellular formation of aldehyde-protein adducts during early stages of alcohol-induced liver injury.

METHODS

Female Sprague Dawley(R) rats were subjected to the intragastric administration of a low-carbohydrate/high-fat total enteral nutrition diet or a total enteral nutrition diet containing ethanol for a period of 36 days. Indexes of hepatic responses to ethanol were evaluated in terms of changes in plasma alanine aminotransferase activity, hepatic histopathologic analysis, and induction of cytochrome P-4502E1 (CYP2E1). Immunohistochemical methods were used to detect hepatic proteins modified with malondialdehyde (MDA) or 4-hydroxynonenal (4-HNE) for subsequent quantitative image analysis.

RESULTS

After 36 days of treatment, rats receiving the alcohol-containing diet displayed hepatic histopathologies characterized by marked micro- and macrosteatosis associated with only minor inflammation and necrosis. Alcohol administration resulted in a 3-fold elevation of plasma alanine aminotransferase activity and 3-fold increases (p < 0.01) in hepatic CYP2E1 apoprotein and activity. Quantitative immunohistochemical analysis revealed significant (p < 0.01) 5-fold increases in MDA- and 4-HNE modified proteins in liver sections prepared from rats treated with alcohol. The MDA- or 4-HNE modified proteins were contained in hepatocytes displaying intact morphology and were colocalized primarily with microvesicular deposits of lipid. Aldehyde-modified proteins were not prevalent in parenchymal or nonparenchymal cells associated with foci of necrosis or inflammation.

CONCLUSIONS

These results suggest that alcohol-induced lipid peroxidation is an early event during alcohol-mediated liver injury and may be a sensitizing event resulting in the production of bioactive aldehydes that have the potential to initiate or propagate ensuing proinflammatory or profibrogenic cellular events.

Reduction of flobufen in pig hepatocytes: effect of pig breed (domestic, wild) and castration

Knowledge of the biotransformation processes of veterinary drugs and food supplements in food-producing animals is increasingly important. Residual levels of parent compounds or their metabolites in food of animal origin may differ with the breed, breeding conditions, and gender of animals. The nonsteroidal antiinflammatory drug flobufen, 4-(2',4'-difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic acid (racemic or its individual enantiomers) was used as a model to evaluate differences in activity, stereoselectivity, and stereospecificity of reductases in primary cultures of hepatocytes from intact male or castrated male domestic pigs (Sus scrofa domestica) or male wild pig (Sus scrofa scrofa). Time-dependent consumption of flobufen enantiomers and formation of dihydroflobufen (DHF) diastereoisomers as their principal metabolites in hepatocytes were measured using chiral HPLC. Flobufen reduction in hepatocytes from all three experimental groups of animals was stereoselective ((+)-R-flobufen was predominantly metabolized) and stereospecific (2R;4S-DHF and 2S;4S-DHF diastereoisomers were preferentially formed). Flobufen reductases activity in male domestic pigs was 30 times higher compared to castrated pigs. Flobufen reductases activity was similar in domestic and wild pigs. The stereospecificity and stereoselectivity of DHF production did not significantly differ with breed or castration of animal. Chiral inversion of flobufen enantiomers was also studied and differences between castrated and intact male pigs were seen.

Oxidative stress in viral and alcoholic hepatitis

Liver damage ranges from acute hepatitis to hepatocellular carcinoma, through apoptosis, necrosis, inflammation, immune response, fibrosis, ischemia, altered gene expression and regeneration, all processes that involve hepatocyte, Kupffer, stellate, and endothelial cells. Reactive oxygen and nitrogen species (ROS, RNS) play a crucial role in the induction and in the progression of liver disease, independently from its etiology. They are involved in the transcription and activation of a large series of cytokines and growth factors that, in turn, can contribute to further production of ROS and RNS. The main sources of free radicals are represented by hepatocyte mitochondria and cytochrome p450 enzymes, by endotoxin-activated macrophages (Kupffer cells), and by neutrophils. The consequent alteration of cellular redox state is potentiated by the correlated decrease of antioxidant and energetic reserves. Indices of free radical-mediated damage, such as the increase of malondialdehyde, 4-hydroxynonenal, protein-adducts, peroxynitrite, nitrotyrosine, etc., and/or decrease of glutathione, vitamin E, vitamin C, selenium, etc., have been documented in patients with viral or alcoholic liver disease. These markers may contribute to the monitoring the degree of liver damage, the response to antiviral therapies and to the design of new therapeutic strategies. In fact, increasing attention is now paid to a possible "redox gene therapy." By enhancing the antioxidant ability of hepatocytes, through transgene vectors, one could counteract oxidative/nitrosative stress and, in this way, contribute to blocking the progression of liver disease.

Sex differences in hepatic gene expression in a rat model of ethanol-induced liver injury

Sex differences in susceptibility to alcohol-induced liver injury have been observed in both humans and experimental animal models. Using a standard model of alcohol-induced fatty liver injury and microarray analysis, we have identified differential expression of hepatic genes in both sexes. The genes that exhibit differential expression are of three types: those that are changed only in male rats fed alcohol, those that change in only female rats fed alcohol, and those that change in both sexes, although not always in the same manner. Certain of the differentially expressed genes have previously been identified as participants in the induction of alcohol-induced liver injury. However, this analysis has identified a number of genes that heretofore have not been implicated in alcoholic liver injury; such genes may provide new areas of investigation into the pathogenesis of this 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.

Alcoholic skeletal muscle myopathy: definitions, features, contribution of neuropathy, impact and diagnosis

Alcohol misusers frequently have difficulties in gait, and various muscle symptoms such as cramps, local pain and reduced muscle mass. These symptoms are common in alcoholic patients and have previously been ascribed as neuropathological in origin. However, biochemical lesions and/or the presence of a defined myopathy occur in alcoholics as a direct consequence of alcohol misuse. The myopathy occurs independently of peripheral neuropathy, malnutrition and overt liver disease. Chronic alcoholic myopathy is characterized by selective atrophy of Type II fibres and the entire muscle mass may be reduced by up to 30%. This myopathy is arguably the most prevalent skeletal muscle disorder in the Western Hemisphere and occurs in approximately 50% of alcohol misusers. Alcohol and acetaldehyde are potent inhibitors of muscle protein synthesis, and both contractile and non-contractile proteins are affected by acute and chronic alcohol dosage. Muscle RNA is also reduced by mechanisms involving increased RNase activities. In general, muscle protease activities are either reduced or unaltered, although markers of muscle membrane damage are increased which may be related to injury by reactive oxygen species. This supposition is supported by the observation that in the UK, alpha-tocopherol status is poor in myopathic alcoholics. Reduced alpha-tocopherol may pre-dispose the muscle to metabolic injury. However, experimental alpha-tocopherol supplementation is ineffective in preventing ethanol-induced lesions in muscle as defined by reduced rates of protein synthesis and in Spanish alcoholics with myopathy, there is no evidence of impaired alpha-tocopherol status. In conclusion, by a complex series of mechanisms, alcohol adversely affects skeletal muscle. In addition to the mechanical changes to muscle, there are important metabolic consequences, by virtue of the fact that skeletal muscle is 40% of body mass and an important contributor to whole-body protein turnover.

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.

Alcoholic liver disease

Important mechanisms responsible for alcohol-induced liver injury include mitochondrial damage and loss of ATP, formation of acetaldehyde-and other aldehyde-protein adducts, release of reactive oxygen species (ROS) from mitochondrial electron transfer chain, CYP2E1 , and activated Kupffer cells (KCs); weakening of antioxidant defense systems; and increased intestinal permeability with endotoxemia. Endotoxin interacts with ethanol and/or acetaldehyde, and such interaction leads to a complex cascade of autocrine and paracrine pathways that involve the release of cytokines (proinflammatory, anti-inflammatory, and mutagenic), chemokines, and eicosanoids. These pathways are mediated by activation of KCs, induction of proliferation, and other phenotype changes in hepatic stellate cells (HSCs) leading to transformation to myofibroblasts (the latter is responsible for fibrogenesis, chemotaxis, and contractility, therefore contributing to portal hypertension, angiogenic response, and release of additional cytokines), and stimulation of sinusoidal cells (SECs) to release adhesive molecules and cytokines. Recent data implicate a likely role of apoptosis as a mechanism of hepatocyte cell death in alcoholic liver disease.