Synergistic association between alcohol intake and body mass index with serum alanine and aspartate aminotransferase levels in older adults: the Rancho Bernardo Study

Protective Effects of Diallyl Sulfide Against Ethanol-Induced Injury in Rat Adipose Tissue and Primary Human Adipocytes

BACKGROUND

Alcohol consumption is the fourth leading cause of death and disability worldwide. Several cellular pathways contribute to alcohol-mediated tissue injury. Adipose tissue apart from functioning as an endocrine organ secretes several hormones and cytokines known as adipokines that are known to play a significant role in alcohol-induced tissue damage. This study was designed to test the efficacy of diallyl sulfide (DAS) in regulating the alcohol-induced outcomes on adipose tissue.

METHODS

Male Wistar rats were fed with 36% Lieber-DeCarli liquid diet containing ethanol (EtOH) for 4 weeks. Control rats were pair-fed with isocaloric diet containing maltodextrin instead of EtOH. During the last week of feeding protocol, the EtOH-fed rat group was given 200 mg/kg body weight of DAS through diet. We also studied DAS effect on isolated human primary adipocytes. Viability of human primary adipocytes on DAS treatment was assessed by MTT assay. Malondialdehyde (MDA), a marker of oxidative stress, was measured by HPLC and the thiobarbituric acid method. Expression of inflammatory genes and lipogenic genes was studied by qRT-PCR and Western blotting. Serum inflammatory gene expression was studied by ELISA.

RESULTS

Our study results showed that DAS could alleviate EtOH-induced expression levels of proinflammatory and endoplasmic reticulum (ER) stress genes and improve adipose tissue mass and adipocyte morphology in male Wistar rats fed Lieber-DeCarli diet containing 6% EtOH. Further, we showed that DAS reduced the expression of lipogenic genes and improved lipid accumulation and adipocyte mass in human primary adipocytes treated with EtOH. Subsequently, we also showed that oxidative stress, as measured by the changes in MDA levels, was reduced in both male Wistar rats and human primary adipocytes treated with EtOH plus DAS.

CONCLUSIONS

Our study results prove that DAS is effective in ameliorating EtOH-induced damage to adipose tissue as evidenced by the reduction brought about by DAS in oxidative stress, ER stress, and proinflammatory gene expression levels. DAS treatment also regulated lipogenic gene expression levels, thereby reducing free fatty acid release. In conclusion, this study has clinical implications with respect to alcohol-induced adipose tissue injury among alcohol users.

The epidemiology of non-alcoholic fatty liver disease

The increase in Non-alcoholic Fatty Liver Disease (NAFLD) and the imminent disappearance of chronic viral hepatitis thanks to new and effective therapies is motivating hepatologists to change their clinical approach to chronic liver disease. NAFLD-cirrhosis or NAFLD-Hepatocellular Carcinoma (HCC) are now the second cause of liver transplantation in the USA. This short-review is focused to the epidemiology of NAFLD/Non-alchoholic Steatohepatitis (NASH), including the definition of this disease which should be revised as well discussing the prevalence, risk factors for progression, natural history and mortality. NAFLD is considered to be the hepatic manifestation of the metabolic syndrome (MS). It affects 25-30% of the general population and the risk factors are almost identical to those of MS. The natural history involves either the development of cardiovascular diseases or cirrhosis and HCC. HCC can also develop in NASH in the absence of cirrhosis (45% of cases). We conclude that an international consensus conference on the definition, natural history, policies of surveillance and new pharmacological treatments of NAFLD and NASH is urgently needed.

The Effects of Alcohol on Other Chronic Liver Diseases

Alcohol consumption is often a comorbid condition in other chronic liver diseases. It has been shown to act in synergy to increase liver injury in viral hepatitis, hereditary hemochromatosis, and nonalcoholic fatty liver disease (NAFLD), leading to an increased risk of cirrhosis, hepatocellular carcinoma, and liver-related mortality. Data suggest that modest alcohol consumption may be inversely related to the risk of developing NAFLD and lower rates of progression of NAFLD to nonalcoholic steatohepatitis (NASH). This article reviews data on the relationship between alcohol consumption and other chronic liver diseases.

Alcoholic liver disease: the gut microbiome and liver cross talk

Alcoholic liver disease (ALD) is a leading cause of morbidity and mortality worldwide. Alcoholic fatty liver disease can progress to steatohepatitis, alcoholic hepatitis, fibrosis, and cirrhosis. Patients with alcohol abuse show quantitative and qualitative changes in the composition of the intestinal microbiome. Furthermore, patients with ALD have increased intestinal permeability and elevated systemic levels of gut-derived microbial products. Maintaining eubiosis, stabilizing the mucosal gut barrier, or preventing cellular responses to microbial products protect from experimental ALD. Therefore, intestinal dysbiosis and pathological bacterial translocation appear fundamental for the pathogenesis of ALD. This review highlights causes for intestinal dysbiosis and pathological bacterial translocation, their relationship, and consequences for ALD. We also discuss how the liver affects the intestinal microbiota.

Alcohol produces distinct hepatic lipidome and eicosanoid signature in lean and obese

Alcohol- and obesity-related liver diseases often coexist. The hepatic lipidomics due to alcohol and obesity interaction is unknown. We characterized the hepatic lipidome due to 1) alcohol consumption in lean and obese mice and 2) obesity and alcohol interactions. In the French-Tsukamoto mouse model, intragastric alcohol or isocaloric dextrose were fed with either chow (lean) or high-fat, high-cholesterol diet (obese). Four groups (lean, lean alcohol, obese, and obese alcohol) were studied. MS was performed for hepatic lipidomics, and data were analyzed. Alcohol significantly increased hepatic cholesteryl esters and diacyl-glycerol in lean and obese but was more pronounced in obese. Alcohol produced contrasting changes in hepatic phospholipids with significant enrichment in lean mice versus significant decrease in obese mice, except phosphatidylglycerol, which was increased in both lean and obese alcohol groups. Most lysophospholipids were increased in lean alcohol and obese mice without alcohol use only. Prostaglandin E2; 5-, 8-, and 11-hydroxyeicosatetraenoic acids; and 9- and 13-hydroxyoctadecadienoic acids were considerably increased in obese mice with alcohol use. Alcohol consumption produced distinct changes in lean and obese with profound effects of obesity and alcohol interaction on proinflammatory and oxidative stress-related eicosanoids.

Adipose tissue-liver axis in alcoholic liver disease

Alcoholic liver disease (ALD) remains an important health problem worldwide. The disease spectrum is featured by early steatosis, steatohepatitis (steatosis with inflammatory cells infiltration and necrosis), with some individuals ultimately progressing to fibrosis/cirrhosis. Although the disease progression is well characterized, no effective therapies are currently available for the treatment in humans. The mechanisms underlying the initiation and progression of ALD are multifactorial and complex. Emerging evidence supports that adipose tissue dysfunction contributes to the pathogenesis of ALD. In the first part of this review, we discuss the mechanisms whereby chronic alcohol exposure contributed to adipose tissue dysfunction, including cell death, inflammation and insulin resistance. It has been long known that aberrant hepatic methionine metabolism is a major metabolic abnormality induced by chronic alcohol exposure and plays an etiological role in the pathogenesis of ALD. The recent studies in our group documented the similar metabolic effect of chronic alcohol drinking on methionine in adipose tissue. In the second part of this review, we also briefly discuss the recent research progress in the field with a focus on how abnormal methionine metabolism in adipose tissue contributes to adipose tissue dysfunction and liver damage.

Biomarker-Based Approaches for Assessing Alcohol Use Disorders

Although alcohol use disorders rank among the leading public health problems worldwide, hazardous drinking practices and associated morbidity continue to remain underdiagnosed. It is postulated here that a more systematic use of biomarkers improves the detection of the specific role of alcohol abuse behind poor health. Interventions should be initiated by obtaining information on the actual amounts of recent alcohol consumption through questionnaires and measurements of ethanol and its specific metabolites, such as ethyl glucuronide. Carbohydrate-deficient transferrin is a valuable tool for assessing chronic heavy drinking. Activities of common liver enzymes can be used for screening ethanol-induced liver dysfunction and to provide information on the risk of co-morbidities including insulin resistance, metabolic syndrome and vascular diseases. Conventional biomarkers supplemented with indices of immune activation and fibrogenesis can help to assess the severity and prognosis of ethanol-induced tissue damage. Many ethanol-sensitive biomarkers respond to the status of oxidative stress, and their levels are modulated by factors of life style, including weight gain, physical exercise or coffee consumption in an age- and gender-dependent manner. Therefore, further attention should be paid to defining safe limits of ethanol intake in various demographic categories and establishing common reference intervals for biomarkers of alcohol use disorders.

Microbiota Protects Mice Against Acute Alcohol-Induced Liver Injury

BACKGROUND

Our aim is to investigate the physiological relevance of the intestinal microbiota in alcohol-induced liver injury. Chronic alcohol abuse is associated with intestinal bacterial overgrowth, increased intestinal permeability, and translocation of microbial products from the intestine to the portal circulation and liver. Translocated microbial products contribute to experimental alcoholic liver disease.

METHODS

We subjected germ-free and conventional C57BL/6 mice to a model of acute alcohol exposure that mimics binge drinking.

RESULTS

Germ-free mice showed significantly greater liver injury and inflammation after oral gavage of ethanol (EtOH) compared with conventional mice. In parallel, germ-free mice exhibited increased hepatic steatosis and up-regulated expression of genes involved in fatty acid and triglyceride synthesis compared with conventional mice after acute EtOH administration. The absence of microbiota was also associated with increased hepatic expression of EtOH-metabolizing enzymes, which led to faster EtOH elimination from the blood and lower plasma EtOH concentrations. Intestinal levels of EtOH-metabolizing genes showed regional expression differences and were overall higher in germ-free mice relative to conventional mice.

CONCLUSIONS

Our findings indicate that absence of the intestinal microbiota increases hepatic EtOH metabolism and the susceptibility to binge-like alcohol drinking.

Short- or long-term high-fat diet feeding plus acute ethanol binge synergistically induce acute liver injury in mice: an important role for CXCL1

Obesity and alcohol consumption often coexist and work synergistically to promote steatohepatitis; however, the underlying mechanisms remain obscure. Here, we demonstrate that feeding mice a high-fat diet (HFD) for as little as 3 days markedly exacerbated acute ethanol binge-induced liver neutrophil infiltration and injury. Feeding mice with an HFD for 3 months plus a single binge of ethanol induced much more severe steatohepatitis. Moreover, 3-day or 3-month HFD-plus-ethanol binge (3d-HFD+ethanol or 3m-HFD+ethanol) treatment markedly up-regulated the hepatic expression of several chemokines, including chemokine (C-X-C motif) ligand 1 (Cxcl1), which showed the highest fold (approximately 20-fold and 35-fold, respectively) induction. Serum CXCL1 protein levels were also markedly elevated after the HFD+ethanol treatment. Blockade of CXCL1 with a CXCL1 neutralizing antibody or genetic deletion of the Cxcl1 gene reduced the HFD+ethanol-induced hepatic neutrophil infiltration and injury, whereas overexpression of Cxcl1 exacerbated steatohepatitis in HFD-fed mice. Furthermore, expression of Cxcl1 messenger RNA was up-regulated in hepatocytes, hepatic stellate cells, and endothelial cells isolated from HFD+ethanol-fed mice compared to mice that were only given the HFD, with the highest fold induction observed in hepatocytes. In vitro stimulation of hepatocytes with palmitic acid up-regulated the expression of Cxcl1 messenger RNA, and this up-regulation was attenuated after treatment with an inhibitor of extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase, or nuclear factor κB. In addition, hepatic or serum levels of free fatty acids were higher in HFD+ethanol-fed mice than in the control groups.

CONCLUSION

An HFD combined with acute ethanol consumption synergistically induces acute liver inflammation and injury through the elevation of hepatic or serum free fatty acids and subsequent up-regulation of hepatic CXCL1 expression and promotion of hepatic neutrophil infiltration.

Effect of chronic alcohol consumption on the development and progression of non-alcoholic fatty liver disease (NAFLD)

A number of epidemiologic studies show a protective effect of light to moderate daily alcohol consumption on the development of non-alcoholic fatty liver disease (NAFLD). Although these small amounts of ethanol may prevent fatty liver, they may also be a risk factor for other diseases such as breast and colon cancer. Those individuals who have underlying hepatic steatosis or non-alcoholic steatohepatitis (NASH) should not use ethanol chronically since the data available at present do not support a beneficial effect of alcohol in this situation. Especially overweight and obese individuals may be more susceptible towards alcohol even at moderate doses. Animal experiments show a negative effect of ethanol on liver histology in either dietary or genetic NASH models. In addition, patients with NASH reveal a significant increased risk for hepatocellular cancer (HCC) even with social alcohol consumption. Thus, subjects with underlying NASH should abstain from alcohol at any amounts.

Insulin resistance in clinical and experimental alcoholic liver disease

Alcoholic liver disease (ALD) is the number one cause of liver failure worldwide; its management costs billions of healthcare dollars annually. Since the advent of the obesity epidemic, insulin resistance (IR) and diabetes have become common clinical findings in patients with ALD; and the development of IR predicts the progression from simple steatosis to cirrhosis in ALD patients. Both clinical and experimental data implicate the impairment of several mediators of insulin signaling in ALD, and experimental data suggest that insulin-sensitizing therapies improve liver histology. This review explores the contribution of impaired insulin signaling in ALD and summarizes the current understanding of the synergistic relationship between alcohol and nutrient excess in promoting hepatic inflammation and disease.

Review and Recommendations for the Component Tests in the Liver Function Test Profile

Pathology laboratories group some tests that they perform on their high throughput biochemistry analysers into profiles of tests that are associated with different organs (e.g. liver function tests-LFT). The components of these profiles are historic and often vary between different laboratories. This can lead to confusion and begs the question of what should be in a particular profile. In community medicine profiles may be used as screening tests but some of the components of the profiles may have low sensitivity and specificity and may produce both false positives and negatives. The LFT may include components which are poor liver function tests but are sensitive to fatty liver and hence elevations may cause unnecessary concern. Harmonisation of clinical chemistry reference intervals and units is occurring now so it is time to consider a similar process for components of a profile. A proposed list of analytes to be performed in the LFT profile is given.

Non-alcoholic fatty liver disease: what the clinician needs to know

Non-alcoholic fatty liver disease (NAFLD) is the most frequent cause of liver disease in the Western world. Furthermore, it is increasing worldwide, paralleling the obesity pandemic. Though highly frequent, only about one fifth of affected subjects are at risk of developing the progressive form of the disease, non-alcoholic steatohepatitis with fibrosis. Even in the latter, liver disease is slowly progressive, though, since it is so prevalent, it is already the third cause of liver transplantation in the United States, and it is predicted to get to the top of the ranking in few years. Of relevance, fatty liver is also associated with increased overall mortality and particularly increased cardiovascular mortality. The literature and amount of published papers on NAFLD is increasing as fast as its prevalence, which makes it difficult to keep updated in this topic. This review aims to summarize the latest knowledge on NAFLD, in order to help clinicians understanding its pathogenesis and advances on diagnosis and treatment.

Impacts of common factors of life style on serum liver enzymes

AIM: To investigate the impacts of gender, age and factors of life style (alcohol, overweight, coffee and smoking) on serum liver enzymes.

METHODS: Serum alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) were measured from 6269 apparently healthy individuals (2851 men, 3418 women, mean age 45 ± 12 years, range 25-74 years) in a national cross-sectional health survey. All subjects underwent detailed clinical examinations and interviews including the amount and pattern of alcohol use, coffee consumption and smoking habits.

RESULTS: In this population with a mean ± SD alcohol consumption of 65 ± 105 g/wk and body mass index (BMI) of 26.1 ± 4.3 kg/m², both ALT and GGT were significantly influenced by alcohol use (P < 0.001) and BMI (P < 0.001), whereas smoking increased only GGT (P < 0.001). A significant effect of age on ALT was seen in men (P < 0.001) whereas not in women. Significant two-factor interactions of alcohol use in men were observed with age (ALT: P < 0.01; GGT: P < 0.001) and BMI (GGT: P < 0.05). For ALT, a significant interaction also occurred between BMI and age (P < 0.005). In contrast, women showed significant interactions of alcohol use with BMI (GGT: P < 0.05), smoking (GGT: P < 0.001), and coffee consumption (GGT: P < 0.001).

CONCLUSION: Life-style associated changes in liver enzymes may reflect health risks, which should be considered in the definition of normal limits for liver enzymes.

Non-alcoholic fatty liver disease, obesity and the metabolic syndrome

Nonalcoholic fatty liver disease (NAFLD) is now recognized as the most common cause of chronic liver disease worldwide. Its prevalence has increased to more than 30% of adults in developed countries and its incidence is still rising. The majority of patients with NAFLD have simple steatosis but in up to one third of patients, NAFLD progresses to its more severe form nonalcoholic steatohepatitis (NASH). NASH is characterized by liver inflammation and injury thereby determining the risk to develop liver fibrosis and cancer. NAFLD is considered the hepatic manifestation of the metabolic syndrome. However, the liver is not only a passive target but affects the pathogenesis of the metabolic syndrome and its complications. Conversely, pathophysiological changes in other organs such as in the adipose tissue, the intestinal barrier or the immune system have been identified as triggers and promoters of NAFLD progression. This article details the pathogenesis of NAFLD along with the current state of its diagnosis and treatment.

Rectification of impaired adipose tissue methylation status and lipolytic response contributes to hepatoprotective effect of betaine in a mouse model of alcoholic liver disease

BACKGROUND AND PURPOSE

Overactive lipolysis in adipose tissue contributes to the pathogenesis of alcoholic liver disease (ALD); however, the mechanisms involved have not been elucidated. We previously reported that chronic alcohol consumption produces a hypomethylation state in adipose tissue. In this study we investigated the role of hypomethylation in adipose tissue in alcohol-induced lipolysis and whether its correction contributes to the well-established hepatoprotective effect of betaine in ALD.

EXPERIMENTAL APPROACH

Male C57BL/6 mice were divided into four groups and started on one of four treatments for 5 weeks: isocaloric pair-fed (PF), alcohol-fed (AF), PF supplemented with betaine (BT/AF) and AF supplemented with betaine (BT/AF). Betaine, 0.5% (w v(-1) ), was added to the liquid diet. Both primary adipocytes and mature 3T3-L1 adipocytes were exposed to demethylation reagents and their lipolytic responses determined.

KEY RESULTS

Betaine alleviated alcohol-induced pathological changes in the liver and rectified the impaired methylation status in adipose tissue, concomitant with attenuating lipolysis. In adipocytes, inducing hypomethylation activated lipolysis through a mechanism involving suppression of protein phosphatase 2A (PP2A), due to hypomethylation of its catalytic subunit, leading to increased activation of hormone-sensitive lipase (HSL). In line with in vitro observations, reduced PP2A catalytic subunit methylation and activity, and enhanced HSL activation, were observed in adipose tissue of alcohol-fed mice. Betaine attenuated this alcohol-induced PP2A suppression and HSL activation.

CONCLUSIONS AND IMPLICATIONS

In adipose tissue, a hypomethylation state contributes to its alcohol-induced dysfunction and an improvement in its function may contribute to the hepatoprotective effects of betaine in ALD.

Association of serum bilirubin with aging and mortality

BACKGROUND AND AIMS

Bilirubin, a breakdown product of heme metabolism, has been shown to be protective against cardiovascular mortality; however, it is also a marker of liver function. There are limited data on the longitudinal changes in bilirubin with aging in a population-based cohort of older adults. This study was designed to determine whether serum bilirubin changes with age in older adults, and to evaluate whether age attenuates the association between bilirubin and mortality.

METHODS

This is a prospective cohort study of 2364 participants with a mean age of 70 years, who completed a research clinic visit from 1984 to 1987, and 1703 participants who returned for a second research visit approximately 8 years later. Cross-sectional and longitudinal multivariable-adjusted analyses were performed to examine the association between serum bilirubin, aging, and mortality.

RESULTS

In cross-sectional analyses, when the cohort was divided into quartiles of age, higher baseline serum bilirubin levels were associated with older age in analyses adjusted for sex, body mass index (BMI), alanine aminotransferase (ALT), albumin, and metabolic traits (P-value <0.001). In longitudinal analyses, among the subset of participants who had two research visits, aging remained significantly associated with an increase in bilirubin in multivariable-adjusted models (P-value <0.0001). When the longitudinal cohort was divided into bilirubin quartiles, Kaplan-Meier analysis showed an incremental reduction in survival with higher bilirubin levels (P-value = 0.002); however, this association between bilirubin quartile and mortality was no longer significant after adjusting for age (P-value 0.30), suggesting higher bilirubin in older age does not confer survival advantage.

CONCLUSIONS

Serum bilirubin levels gradually increase with age in older adults. Elevated bilirubin in older individuals is not associated with improved survival as previously reported in middle-aged populations.

The impact of obesity and metabolic syndrome on alcoholic liver disease

Alcoholic liver disease (ALD) remains a major cause of chronic liver diseases and liver failure. Population-based prospective studies and patient cohort studies have demonstrated that obesity and the metabolic syndrome exacerbate progression of ALD and increase hepatocellular carcinoma (HCC) incidence and mortality. Emerging evidence also suggests a synergism between alcohol and obesity in mortality and HCC incidence. Recognition of these increased risks and detection of early-stage liver disease may offer the opportunity to address these modifiable risk factors and prevent disease progression in these patients.

The de ritis ratio: the test of time

De Ritis described the ratio between the serum levels of aspartate transaminase (AST) and alanine transaminase (ALT) almost 50 years ago. While initially described as a characteristic of acute viral hepatitis where ALT was usually higher than AST, other authors have subsequently found it useful in alcoholic hepatitis, where AST is usually higher than ALT. These interpretations are far too simplistic however as acute viral hepatitis can have AST greater than ALT, and this can be a sign of fulminant disease, while alcoholic hepatitis can have ALT greater than AST when several days have elapsed since alcohol exposure. The ratio therefore represents the time course and aggressiveness of disease that would be predicted from the relatively short half-life of AST (18 h) compared to ALT (36 h). In chronic viral illnesses such as chronic viral hepatitis and chronic alcoholism as well as non-alcoholic fatty liver disease, an elevated AST/ALT ratio is predictive of long terms complications including fibrosis and cirrhosis. There are methodological issues, particularly whether or not pyridoxal phosphate is used in the transaminase assays, and although this can have specific effects when patient samples are deficient in this vitamin, these method differences generally have mild effects on the usefulness of the assays or the ratio. Ideally laboratories should be using pyridoxal phosphate supplemented assays in alcoholic, elderly and cancer patients who may be pyridoxine deplete. Ideally all laboratories reporting abnormal ALT should also report AST and calculate the De Ritis ratio because it provides useful diagnostic and prognostic information.

Individual and joint impacts of ethanol use, BMI, age and gender on serum gamma-glutamyltransferase levels in healthy volunteers

Excessive ethanol consumption, obesity and increasing age may all lead to increased serum levels of gamma-glutamyltransferase (GGT) enzyme, which plays a key role in the metabolism of extracellular reduced glutathione. However, as yet, the interactions between the various modulators of GGT activities have remained poorly defined. We analyzed data from 15,617 apparently healthy individuals (7254 men and 8363 women, mean age 46 ± 13 years, range 25–74 years) who participated in a national cross-sectional health survey in Finland between 1997 and 2007. All subjects underwent detailed clinical examinations and interviews, including the amount of ethanol use and smoking habits. GGT levels were measured from all participants, and the individual and joint impacts of the different study variables on GGT levels were assessed. Significant individual effects were noted for ethanol use (p < 0.001), body mass index (BMI) (p < 0.001), age (p < 0.001) and smoking (p < 0.001). In men, significant two-factor interactions occurred between ethanol use and age (p < 0.020). Among those over 40 years of age, ethanol consumption was found to be a stronger determinant of increased GGT levels than in men below 40 years, whereas in the latter age group, BMI was found to predominate. In women, a significant two-factor interaction occurred between ethanol and BMI (p = 0.010), whereas it did not with ethanol use and age. The data underscores the role of ethanol consumption and age as major determinants of increased GGT levels in men, whereas in women, a relatively stronger impact was noted for ethanol intake and BMI. In light of the ability of GGT enzyme to modulate crucial redox-sensitive functions, the present findings also support the use of GGT as a biomarker of oxidative stress.

Serum γ-glutamyltranspeptidase predicts all-cause, cardiovascular and liver mortality in older adults

BACKGROUND

Serum γ-glutamyltranspeptidase (GGT), a marker of fatty liver disease (FLD), predicts mortality in young adults. However, the association between serum GGT and mortality in older adults is unclear.

OBJECTIVES

To examine if elevated serum GGT predicts all-cause, cardiovascular (CVD), and liver mortality in community-dwelling older adults.

DESIGN AND SETTING

A prospective cohort study including 2364 participants (mean-age 70 yr, BMI-24.5 kg/m², 54% women) from the Rancho Bernardo Study who attended a research visit in 1984-87 when multiple metabolic covariates were ascertained including serum GGT. They were followed for a mean (± standard deviation) of 13.7 (±6.2) years.

MEASUREMENT

Multivariable-adjusted Cox-proportional hazards analyses were conducted to examine the association between elevated serum GGT (>51 U/L in men and > 33 U/L in women) and all-cause, CVD, and liver mortality.

RESULTS

In these older men and women, cumulative mortality was 56.2% (n=1329) with CVD and liver mortality accounting for 49.4% and 2.3% of all deaths, respectively, over 32,387 person-years of follow-up. In multivariate analyses (adjusted for age, sex, alcohol use, body-mass-index, total cholesterol, HDL cholesterol, serum triglyceride, smoking status, systolic blood pressure, diabetes mellitus, serum interleukin-6, and c-reactive protein), serum GGT elevation was significantly associated with all-cause (HR, 1.55, 95% CI, 1.21-1.98), CVD (HR, 1.51, 95% CI, 1.04-2.17), and liver mortality (HR, 9.10, 95% CI, 3.42-24.26).

CONCLUSIONS

In community-dwelling older adults, serum GGT is an independent predictor of all-cause, CVD, and liver mortality.

Synergism between obesity and alcohol in increasing the risk of hepatocellular carcinoma: a prospective cohort study

Obesity and alcohol interact to increase the risk of death from liver failure in men. In the present study, we aimed to examine whether obesity and alcohol were multiplicative or additive in increasing the risk of hepatocellular carcinoma (HCC) in both men and women. We conducted a prospective, population-based study of 23,712 Taiwanese residents (50.3% men) from 7 townships who underwent an evaluation for liver disease and were followed for 11.6 years for incident HCC. The mean age was 47 (standard deviation, 10) years and the mean body mass index (weight (kg)/height (m)(2)) was 24 (standard deviation, 3). Overall, 305 cases of HCC were identified over 275,126 person-years of follow-up. Age, male sex, alcohol drinking, cigarette smoking, elevated alanine aminotransferase, serum hepatitis B surface antigen, anti-hepatitis C virus positivity, and diabetes mellitus were each statistically significant predictors of incident HCC in univariate analyses (P < 0.05). Alcohol use and obesity (body mass index ≥30) showed a synergistic association with the risk of incident HCC in both unadjusted analyses (hazard ratio = 7.19, 95% confidence interval: 3.69, 14.00; P < 0.01) and multivariable-adjusted analyses (age, sex, smoking, serum alanine aminotransferase, serum hepatitis B surface antigen, anti-hepatitis C virus antibody, and diabetes mellitus) (hazard ratio = 3.82, 95% confidence interval: 1.94, 7.52; P < 0.01). Relative excess risks due to interaction, attributable proportion, and synergy index were 4.83, 0.67, and 4.53, respectively, suggesting a multiplicative interaction between alcohol use and obesity. Obesity and alcohol synergistically increase the risk of incident HCC.

Ethanol administration exacerbates the abnormalities in hepatic lipid oxidation in genetically obese mice

Alcohol consumption synergistically increases the risk and severity of liver damage in obese patients. To gain insight into cellular or molecular mechanisms underlying the development of fatty liver caused by ethanol-obesity synergism, we have carried out animal experiments that examine the effects of ethanol administration in genetically obese mice. Lean wild-type (WT) and obese (ob/ob) mice were subjected to ethanol feeding for 4 wk using a modified Lieber-DeCarli diet. After ethanol feeding, the ob/ob mice displayed much more pronounced changes in terms of liver steatosis and elevated plasma levels of alanine aminotransferase and aspartate aminotransferase, indicators of liver injury, compared with control mice. Mechanistic studies showed that ethanol feeding augmented the impairment of hepatic sirtuin 1 (SIRT1)-AMP-activated kinase (AMPK) signaling in the ob/ob mice. Moreover, the impairment of SIRT1-AMPK signaling was closely associated with altered hepatic functional activity of peroxisome proliferator-activated receptor γ coactivator-α and lipin-1, two vital downstream lipid regulators, which ultimately contributed to aggravated fatty liver observed in ethanol-fed ob/ob mice. Taken together, our novel findings suggest that ethanol administration to obese mice exacerbates fatty liver via impairment of the hepatic lipid metabolism pathways mediated largely by a central signaling system, the SIRT1-AMPK axis.

Updated thresholds for serum alanine aminotransferase level in a large-scale population study composed of 34 346 subjects

BACKGROUND

The sensitivity of current upper limit of normal (ULN) of serum alanine aminotransferase (ALT) levels for detecting chronic liver disease has been challenged recently.

AIM

To identify modulating factors for serum ALT levels and to refine its ULN threshold.

METHODS

We enrolled 34 346 consecutive subjects who completed the health check-up at Taipei Veterans General Hospital from 2002 to 2009. ULN was set for healthy ALT level to the 95th percentile of the reference healthy population.

RESULTS

A group of 21 282 subjects were used as a training set to define an ULN with the highest sensitivity; afterwards, this ULN was validated in another set of 13 064 subjects. A reference healthy population was selected from the training set after excluding subjects with any abnormalities in independent risk factors associated with elevated serum ALT level (>40 IU/L) by multivariate analysis like body mass index, waist circumference, glucose, cholesterol, high-density lipoprotein-cholesterol, triglyceride, hepatitis B virus surface antigen, anti-hepatitis C virus antibody and fatty liver. The new ULN of serum ALT level defined as the 95% percentile in the healthy population were 21 IU/L and 17 IU/L for men and women respectively. These cut-off values had the highest Youden's index and areas under the corresponding receiver operating curves among four widely applied thresholds in both the training and validation sets.

CONCLUSIONS

The suggested threshold of upper limit of normal provides better discrimination between healthy and unhealthy status. Viral hepatitis, metabolic syndrome and fatty liver are the major risk factors of elevated serum alanine aminotransferase levels.

What should we recommend to our patients with NAFLD regarding alcohol use?

It is generally recommended that patients with nonalcoholic fatty liver disease (NAFLD) not consume alcohol. However, because these patients are at increased cardiovascular risk, and light to moderate alcohol consumption may have hepatic benefits in people with or at risk for NAFLD, this recommendation may be ill-advised. We reviewed the literature on alcohol consumption and NAFLD and conclude that (i) heavy consumption has many harmful effects, including those on the liver, and should be discouraged whether a person has NAFLD or not; (ii) it is unknown whether cardiovascular and metabolic benefits of light to moderate consumption observed in the general population extend to those with NAFLD; (iii) epidemiological and cohort studies suggesting that light to moderate drinking may have hepatic benefits are largely cross-sectional and used surrogate end points; and (iv) until further data from rigorous prospective studies become available, people with NAFLD should avoid alcohol of any type or amount.

Association between serum interleukin-6 concentrations and mortality in older adults: the Rancho Bernardo study

Background

Interleukin-6 (IL-6) may have a protective role in acute liver disease but a detrimental effect in chronic liver disease. It is unknown whether IL-6 is associated with risk of liver-related mortality in humans.

Aims

To determine if IL-6 is associated with an increased risk of all-cause, cardiovascular disease (CVD), cancer, and liver-related mortality.

Methods

A prospective cohort study included 1843 participants who attended a research visit in 1984–87. Multiple covariates were ascertained including serum IL-6. Multivariable-adjusted Cox proportional hazards regression analyses were used to examine the association between serum IL-6 as a continuous (log transformed) variable with all-cause, CVD, cancer, and liver-related mortality. Patients with prevalent CVD, cancer and liver disease were excluded for cause-specific mortality.

Results

The mean (± standard deviation) age and body-mass-index (BMI) of participants was 68 (±10.6) years and 25 (±3.7) Kg/m², respectively. During the 25,802 person-years of follow-up, the cumulative all-cause, CVD, cancer, and liver-related mortality were 53.1% (N = 978), 25.5%, 11.3%, and 1.3%, respectively. The median (±IQR) length of follow-up was 15.3±10.6 years. In multivariable analyses, adjusted for age, sex, alcohol, BMI, diabetes, hypertension, total cholesterol, HDL, and smoking, one-SD increment in log-transformed serum IL-6 was associated with increased risk of all-cause, CVD, cancer, and liver-related mortality, with hazard ratios of 1.48 (95% CI, 1.33–1.64), 1.38 (95% CI, 1.16–1.65), 1.35 (95% CI, 1.02–1.79), and 1.88 (95% CI, 0.97–3.67), respectively. CRP adjustment attenuated the effects but the association between IL-6 and all-cause and CVD mortality remained statistically significant, independent of CRP levels.

Conclusions

In community-dwelling older adults, serum IL-6 is associated with all-cause, CVD, cancer, and liver-related mortality.

Serum levels of alanine aminotransferase decrease with age in longitudinal analysis

BACKGROUND & AIMS

An increased level of alanine aminotransferase (ALT) is a marker of liver injury. The mean ALT level has been reported to decrease with age; we performed a longitudinal analysis to determine whether serum levels of ALT changes with age among community-dwelling, older adults in the US.

METHODS

We analyzed clinical data from 2 cohorts of individuals who participated in the Rancho Bernardo Study, in Southern CA. The first cohort comprised 1073 community-dwelling participants (59% women); clinical data was collected from 1984-1987 and 1992-1997. The second cohort comprised 416 participants (64% women); data was collected from 1984-1987, 1992-1997, and 1997-1999. Demographic, metabolic covariates, ALT, bilirubin, and albumin were measured. Changes in individual ALT over time were examined in unadjusted and multivariable-adjusted linear and logistic regression analyses.

RESULTS

At the baseline visit, the patients' mean age was 65.7 years and body mass index was 24.9 kg/m(2). In cohort 1, the mean levels of ALT decreased with age by 10% (from 21 to 19 IU/L) between the time periods of 1984-1987 and 1992-1997 (P < .0001). In cohort 2, they decreased by 20% (from 20 to 16 IU/L) between the time periods of 1984-1987 and 1997-1999 (P < .0001). Categorically-defined increases in ALT also decreased with age (P < .0001). Results remained consistent in sex-specific analyses and after adjusting for metabolic syndrome components, alcohol use, bilirubin, and serum levels of albumin (P < .0001).

CONCLUSIONS

In a longitudinal analysis, we observed that levels of ALT decrease with age, independent of sex, metabolic factors, alcohol use, and results from commonly used liver function tests (bilirubin and albumin). When interpreting serum levels of ALT, physicians should consider patients' age especially in the elderly.

Synergistic effect of alcohol consumption and body mass on serum concentrations of cytokeratin-18

BACKGROUND

Cytokeratin-18 is an essential component of the cytoskeleton of epithelial cells (including hepatocytes). Serum concentrations of cytokeratin-18 (tissue polypeptide-specific antigen [TPS]) are used as a marker of epithelial neoplasms. Here, we investigated the potential interaction between alcohol and obesity in relation to serum TPS concentrations.

METHODS

Alcohol consumption, body mass index, and components of metabolic syndrome were measured in a random sample (n = 420) of the adult population (aged 18 to 92 years, 45% men) from a single municipality. Regular alcohol intake of >20 g/d (women) or >30 g/d (men) was considered risky drinking. Serum TPS was measured with a commercial immunoassay.

RESULTS

Risky drinking was associated with increased serum concentrations of TPS, which was particularly evident among obese individuals. Among individuals without risky drinking, TPS concentrations were similar for all levels of body mass. Conversely, among risky drinkers, serum TPS concentrations increased in parallel with body mass (p = 0.002). The odds ratio of a high (>100 U/l) TPS concentration for the combination of risky drinking and obesity was greater than the additive effect of the 2 separate factors, after adjusting for age and sex. A similar interaction was observed between risky drinking and abdominal adiposity, a major component of the metabolic syndrome. Serum TPS concentrations were correlated with markers of liver damage. Serum TPS was not superior to standard markers (gamma-glutamyl transferase and red blood cell mean volume) for the detection of risky drinking.

CONCLUSIONS

There is a synergism between risky alcohol consumption and common metabolic disorders (particularly obesity) in relation to serum concentrations of cytokeratin-18 (TPS), which probably reflect liver disease.

Liver enzymes, type 2 diabetes, and metabolic syndrome in middle-aged, urban Chinese men

BACKGROUND

We examined associations between elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT) with physical activity and obesity measures in middle-aged urban Chinese men. The associations between elevated aminotransferases with impaired fasting glucose, newly diagnosed type 2 diabetes (T2D), and metabolic syndrome were also evaluated in this population.

METHODS

The study included 3,978 urban Chinese men 40-74 years of age from a population-based cohort study, the Shanghai Men's Health Study, who were free of T2D at baseline and had provided fasting blood samples. Elevated AST and ALT levels were defined as >40 U/L. Anthropometric measurements and information on lifestyle factors and disease history were collected by in-person interviews.

RESULTS

A total of 11.13% and 5.85% study participants had elevated serum ALT and AST levels, respectively. Both body mass index (BMI) and waist-to-hip ratio (WHR) were positively associated with elevated ALT and AST. We found stronger associations between ALT and BMI/WHR than between AST and BMI/WHR. Physical activity was inversely associated with ALT and AST, but the association was attenuated after adjustment for BMI and WHR. Elevated serum aminotransferase levels were associated with T2D and metabolic syndrome.

CONCLUSIONS

In this representative sample of middle-aged Chinese men, elevated ALT and AST were associated with a prevalence of metabolic syndrome and T2D. These findings suggest that the relationship between obesity and T2D might involve liver injury. Physical activity might reduce the levels of ALT and AST, probably mediated through weight reduction.

Review of current clinical biomarkers for the detection of alcohol dependence

Alcohol dependence is often seen in a variety of clinical settings and requires attention to reduce medical complications, set up appropriate treatments, and minimize utilization of healthcare resources. Patient responses to questionnaires are often used to screen for alcohol problems, but can be misleading in the context of altered mental states or in a patient hesitant to disclose a pattern of alcohol use. Identifying the biochemical consequences of alcohol dependence has led to further study, including correlating laboratory findings to increase accuracy of identifying problem drinkers. Understanding the normal function, mechanism of abnormal findings, sensitivity, and specificity of the current laboratory studies can substantiate clinical suspicion of alcohol use. In this article, we provide results from our literature search regarding laboratory abnormalities in alcohol dependence, review options available to complement a thorough history and physical, and provide a brief overview of future biomarkers for detection of alcohol use.

Alanine aminotransferase decreases with age: the Rancho Bernardo Study

Background

Serum alanine aminotransferase (ALT) is a marker of liver injury. The 2005 American Gastroenterology Association Future Trends Committee report states that serum ALT levels remain constant with age. This study examines the association between serum ALT and age in a community-dwelling cohort in the United States.

Methods

A cross-sectional study of 2,364 (54% female) participants aged 30–93 years from the Rancho Bernardo Study cohort who attended a research clinic visit in 1984–87. Demographic, metabolic co-variates, ALT, bilirubin, gamma glutamyl transferase (GGT), albumin, and adiposity signaling biomarkers (leptin, IL-6, adiponectin, ghrelin) were measured. Participants were divided into four-groups based upon age quartile, and multivariable-adjusted least squares of means (LSM) were examined (p for trend <0.05).

Results

ALT decreased with increasing age, with mean ALT levels (IU/L) of 23, 21, 20, and 17 for those between quartile ages 30–62, 63–71, 72–77, and 78–93 years (p<0.0001). Trends of decreasing LSM ALT with age and the decreasing prevalence of categorically defined elevated serum ALT with age remained robust after adjusting for sex, alcohol use, metabolic syndrome components, and biomarkers of adiposity (p-value <0.0001), and was not materially changed after adjusting for bilirubin, GGT, and albumin.

Conclusions

ALT levels decrease with age in both men and women independent of metabolic syndrome components, adiposity signaling biomarkers, and other commonly used liver function tests. Further studies are needed to understand the mechanisms responsible for a decline in ALT with age, and to establish the optimal cut-point of normal ALT in the elderly.

Obesity and alcohol synergize to increase the risk of incident hepatocellular carcinoma in men

BACKGROUND & AIMS

Body mass index (BMI) and alcohol use are risk factors for hepatocellular carcinoma (HCC). We performed a prospective study to determine if these factors have synergistic effects on HCC risk.

METHODS

Over 14 years, we followed up 2260 Taiwanese men from the Risk Evaluation of Viral Load Elevation and Associated Liver Disease/Cancer-Hepatitis B Virus (REVEAL-HBV) Study Cohort who tested positive for the hepatitis B surface antigen (mean age, 46 ± 10 y; mean BMI, 24 ± 3 kg/m(2)); 20% reported alcohol use. Incident HCC cases were identified via linkage to the national cancer registry. Multivariate-adjusted hazard ratio (HR) and 95% confidence interval (CI) were estimated using Cox-proportional hazards models.

RESULTS

In univariate analysis, the interaction between BMI and alcohol predicted incident HCC (P = .029). Alcohol use and extreme obesity (BMI ≥30 kg/m(2)) had synergistic effects on the risk of incident HCC in analyses adjusted for age (HR, 3.41; 95% CI, 1.25-9.27; P < .025) and multivariables (HR, 3.40; 95% CI, 1.24-9.34; P < .025). The relative risk estimate for the interaction and the attributable proportion from the interaction and synergy index were 1.59, 0.52, and 4.40, respectively; these indicate a multiplicative interaction between alcohol use and extreme obesity. In an analysis stratified into 4 World Health Organization categories of BMI and alcohol use, the risk of incident HCC increased in overweight (HR, 2.4; 95% CI, 1.3-4.4), obese (HR, 2.0; 95% CI, 1.1-3.7), and extremely obese (HR, 2.9; 95% CI, 1.0-8.0) users of alcohol (P for trend = .046).

CONCLUSIONS

Obesity and alcohol have synergistic effects to increase the risk of incident HCC in hepatitis B surface antigen-positive men. Lifestyle interventions might reduce the incidence of HCC.