Joint effects of body weight and alcohol on elevated serum alanine aminotransferase in the United States population

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.

Biphasic effect of alcohol intake on the development of fatty liver disease

BACKGROUND

Fatty liver is an important clinical feature not only in alcoholic and non-alcoholic fatty liver diseases, but in other chronic liver diseases as well. Our aim was to elucidate the effect and relationship between habitual alcohol intake and obesity in the development of fatty liver disease.

METHODS

We enrolled 8,029 subjects undergoing abdominal ultrasonography with general medical examinations, and analyzed the factors associated with fatty liver based on daily alcohol intake, body mass index (BMI), and waist circumference.

RESULTS

For fatty liver, BMI, waist circumference, total cholesterol, triglycerides, and fasting plasma glucose were significant and independent risk factors. Heavy alcohol intake (50 g/day) was a significant risk factor for fatty liver in women (odds ratio [OR], 3.35). Analysis based on the presence or absence of obesity revealed that moderate alcohol intake was a significant negative risk factor for fatty liver in both male and female obese (BMI ≥25 kg/m(2)) subjects (OR, 0.74 for non-obese and 0.39 for obese patients, respectively). Heavy alcohol intake was also a significant negative risk factor in obese males (0.62). In contrast, heavy alcohol intake was a risk factor in non-obese males (OR, 1.29) and in all females (OR, 2.22 for non-obese and 6.6 for obese patients, respectively).

CONCLUSIONS

The influence of alcohol intake on fatty liver differed depending on the level of alcohol consumption, gender, and the presence of obesity, and showed biphasic effects.

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.

Notch signaling and M1 macrophage activation in obesity-alcohol synergism

Macrophages are a key cell type in the innate immune system, and its proinflammatory (M1) activation in the liver plays a critical role in pathogenesis of alcoholic steatohepatitis. Emerging evidence indicates the involvement of Notch signaling in regulation of innate immune response and cellular metabolism. Metabolic switch to glycolysis characterizes macrophages undergoing M1 activation. It has been proposed that metabolic reprograming in response to extrinsic stimulation, such as bacterial endotoxin, triggers intrinsic signal to dictate cell differentiation. Using an obesity-alcohol synergistic ASH mouse model, we have recently shown that Notch1 pathway promotes M1 activation of hepatic macrophages, through direct upregulation of M1 gene transcription and through reprograming of mitochondrial metabolism to glucose oxidation and subsequent mtROS generation to augment M1 gene expression. Our studies demonstrate a novel mechanism of Notch1 signaling in metabolic reprograming of macrophage for M1 activation in ASH.

Copy number variation in exportin-4 (XPO4) gene and its association with histological severity of non-alcoholic fatty liver disease

A recent genome-wide copy number (CNV) scan identified a 13q12.11 duplication in the exportin-4 (XPO4) gene to be associated with non-alcoholic steatohepatitis (NASH). We sought to confirm the finding in a larger cohort and to assess the serum XPO4 pattern in a broad spectrum of non-alcoholic fatty liver disease (NAFLD) cases. We analysed 249 NAFLD patients and 232 matched controls using TaqMan assay and serum XPO4 was measured. Copy number distribution was as follows: copy number neutral (NAFLD: 53.8%, controls: 68.6%), copy number losses (NAFLD: 13.3%, controls: 12.9%), copy number gains (NAFLD: 32.9%, controls: 18.5%). CNV gain was significantly associated with a greater risk of NAFLD (adjusted OR 2.22, 95% CI 1.42–3.46, P = 0.0004) and NASH (adjusted OR 2.33, 95% CI 1.47–3.68, P = 0.0003). Interestingly, subjects carrying extra copy number showed significantly higher serum ALT and triglyceride (P < 0.05). Serum XPO4 levels progressively declined (P = 0.043) from controls (24.6 ng/mL) to simple steatosis (20.8 ng/mL) to NASH (13.8 ng/mL). In conclusion, XPO4 CNV duplication was associated with histological severity of NAFLD, and accompanied by changes in serum XPO4 levels providing insights into NAFLD pathogenesis, and has the potential for biomarker development.

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.

Liver injury correlates with biomarkers of autoimmunity and disease activity and represents an organ system involvement in patients with systemic lupus erythematosus

Liver disease (LD), defined as ≥ 2-fold elevation of aspartate aminotransferase (AST) or alanine aminotransferase (ALT), was examined in a longitudinal study of systemic lupus erythematosus (SLE) patients. Among 435 patients, 90 (20.7%) had LD with a greater prevalence in males (15/39; 38.5%) than females (75/396; 18.9%; p = 0.01). SLE disease activity index (SLEDAI) was greater in LD patients (7.8 ± 0.7) relative to those without (5.8 ± 0.3; p = 0.0025). Anti-smooth muscle antibodies, anti-DNA antibodies, hypocomplementemia, proteinuria, leucopenia, thrombocytopenia, and anti-phospholipid syndrome were increased in LD. An absence of LD was noted in patients receiving rapamycin relative to azathioprine, cyclosporine A, or cyclophosphamide. An absence of LD was also noted in patients treated with N-acetylcysteine. LFTs were normalized and SLEDAI was diminished with increased prednisone use in 76/90 LD patients over 12.1 ± 2.6 months. Thus, LD is attributed to autoimmunity and disease activity, it responds to prednisone, and it is potentially preventable by rapamycin or N-acetylcysteine treatment.

Light alcohol consumption plays a protective role against non-alcoholic fatty liver disease in Japanese men with metabolic syndrome

BACKGROUND & AIMS

Although excess alcohol consumption has been believed to cause liver injury, light alcohol consumption (LAC) has been reported to play a protective role against fatty liver in recent studies. However, the association between non-alcoholic fatty liver disease (NAFLD) and LAC in men with metabolic syndrome (MS) is unclear. The aim of this study was to examine the association between NAFLD and LAC in men with MS.

METHODS

Subjects were 1055 men with MS who underwent a regular health check-up and drank less 20 g/day of alcohol. A distinction was made between non-drinkers and light drinkers and the association between NAFLD and LAC in men with MS was elucidated. NAFLD was referred as fatty liver with alanine aminotransferase (ALT) levels ≧31 IU/L in this study.

RESULTS

Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and the prevalence of NAFLD were significantly lower in light drinkers than in non-drinkers. Logistic regression analysis showed body mass index (BMI), waist circumference (WC), uric acid (UA), haemoglobin A1c (HbA1c), visceral fat type MS and LAC (odds ratios: 0.654; 95% confidence intervals: 0.473-0.906; <0.05) were significant predictors of the prevalence of NAFLD.

CONCLUSION

The prevalence of NAFLD in light drinkers was significantly lower than in non-drinkers, and supporting previous reports studying the general population, LAC is one of the significant predictors of a decreased prevalence of NAFLD in men with MS.

Nonalcoholic fatty liver disease increases the risk of hepatocellular carcinoma in patients with alcohol-associated cirrhosis awaiting liver transplants

BACKGROUND & AIMS

Many patients with alcohol-associated cirrhosis also have diabetes, obesity, or insulin resistance-mediated steatosis, but little is known about how these disorders affect the severity of liver disease. We analyzed the prevalence and prognostic implications of metabolic risk factors (MRFs) such as overweight, diabetes, dyslipidemia, and hypertension in patients with alcohol-associated cirrhosis awaiting liver transplants.

METHODS

We performed a retrospective study of 110 patients with alcohol-associated cirrhosis (77% male; mean age, 55 y; 71% with >6 mo of abstinence) who received liver transplants at a single center in Paris, France, from 2000 through 2013. We collected data on previous exposure to MRFs, steatosis (>10% in the explant), and histologically confirmed hepatocellular carcinoma (HCC).

RESULTS

HCC was detected in explants from 29 patients (26%). Steatosis was detected in explants from 47 patients (70% were abstinent for ≥6 mo); 50% had a history of overweight or type 2 diabetes. Fifty-two patients (47%) had a history of MRFs and therefore were at risk for nonalcoholic fatty liver disease. A higher proportion of patients with MRF had HCC than those without MRF (46% vs 9%; P < .001). A previous history of overweight or type 2 diabetes significantly increased the risk for HCC (odds ratio, 6.23; 95% confidence interval [CI], 2.47-15.76, and odds ratio, 4.63; 95% CI, 1.87-11.47, respectively; P < .001). MRF, but not steatosis, was associated with the development of HCC (odds ratio, 11.76; 95% CI, 2.60-53; P = .001) independent of age, sex, amount of alcohol intake, or severity of liver disease.

CONCLUSIONS

Patients with alcohol-associated cirrhosis who received transplants frequently also had nonalcoholic fatty liver disease. MRFs, particularly overweight, obesity, and type 2 diabetes, significantly increase the risk of HCC.

NOTCH reprograms mitochondrial metabolism for proinflammatory macrophage activation

Metabolic reprogramming is implicated in macrophage activation, but the underlying mechanisms are poorly understood. Here, we demonstrate that the NOTCH1 pathway dictates activation of M1 phenotypes in isolated mouse hepatic macrophages (HMacs) and in a murine macrophage cell line by coupling transcriptional upregulation of M1 genes with metabolic upregulation of mitochondrial oxidative phosphorylation and ROS (mtROS) to augment induction of M1 genes. Enhanced mitochondrial glucose oxidation was achieved by increased recruitment of the NOTCH1 intracellular domain (NICD1) to nuclear and mitochondrial genes that encode respiratory chain components and by NOTCH-dependent induction of pyruvate dehydrogenase phosphatase 1 (Pdp1) expression, pyruvate dehydrogenase activity, and glucose flux to the TCA cycle. As such, inhibition of the NOTCH pathway or Pdp1 knockdown abrogated glucose oxidation, mtROS, and M1 gene expression. Conditional NOTCH1 deficiency in the myeloid lineage attenuated HMac M1 activation and inflammation in a murine model of alcoholic steatohepatitis and markedly reduced lethality following endotoxin-mediated fulminant hepatitis in mice. In vivo monocyte tracking further demonstrated the requirement of NOTCH1 for the migration of blood monocytes into the liver and subsequent M1 differentiation. Together, these results reveal that NOTCH1 promotes reprogramming of mitochondrial metabolism for M1 macrophage activation.

Modest alcohol consumption reduces the incidence of fatty liver in men: a population-based large-scale cohort study

BACKGROUND AND AIM

Recent cross-sectional studies have been reported the possibility that light to moderate alcohol consumption might be negatively associated with fatty liver. However, there has been no large-scale longitudinal study addressing an impact of alcohol consumption on a development of fatty liver diagnosed by ultrasonography. Thus, we investigated the impact of alcohol consumption on a natural history of fatty liver.

METHODS

We analyzed 5437 apparently healthy Japanese who received the health checkup programs repeatedly over 10 years. In this study, we used a standardized questionnaire for addressing the medical history and lifestyle and used a standardized ultrasonographic diagnosis for fatty liver. The total amount of alcohol consumed per week was calculated and classified into four grades; none or minimal, light, moderate, or heavy alcohol consumption (< 40, 40-140, 140-280 or > 280 g/week, respectively). The hazard risks of alcohol consumption for the development of fatty liver were calculated by Cox hazard model after adjusting age, BMI, and parameters for lifestyle.

RESULTS

During 10 years of follow-up, fatty liver was continuously diagnosed just in 10% of men and 20% of women with fatty liver at the baseline. In men, the adjusted hazard risks of light and moderate alcohol consumption for the development of fatty liver were 0.72 (95% confidence interval 0.60-0.86, P < 0.001) and 0.69 (0.57-0.84, P < 0.001), respectively. However, they were not significant in women.

CONCLUSIONS

The newly onset of fatty liver was significantly repressed in apparently healthy men who consume light to moderate alcohol.

Meta-analysis reveals a specific association of the PNPLA3 I148M polymorphism with ALT level in adolescents

AIM

To evaluate potential link between the PNPLA3 rs738409 polymorphism and alanine aminotransferase (ALT) levels through an evidence-based study.

MATERIALS & METHODS

Electronic literature databases, including PubMed, Embase and the Institute for Scientific Information, were searched for relevant studies. Pooling standardized mean differences for quantitative variables and summary odds ratios (OR) were respectively calculated using per-allele comparison.

RESULTS

Although a genotype-phenotype association was inconsistent in adults, this genetic effect was stable in adolescents. There was an approximate increase of 23% in ALT value, and 1.99-fold higher ALT elevation per risk allele increase with low heterogeneity.

CONCLUSION

The PNPLA3 rs738409 polymorphism can have a differentiated influence on ALT level. Our meta-analysis provides reference data for the adjustment of diverse susceptibility due to the rs738409 polymorphism when evaluating liver injury in various populations.

The combined effects of alcohol consumption and body mass index on hepatic steatosis in a general population sample of European men and women

BACKGROUND

Research on the association between alcohol consumption and hepatic steatosis revealed conflictive results.

AIM

To investigate the associations between average daily alcohol consumption and binge drinking with hepatic steatosis, and to analyse combined effects of average daily alcohol consumption and binge drinking with body mass index (BMI) on hepatic steatosis.

METHODS

Data from the population-based Study of Health in Pomerania (SHIP) conducted in north-east Germany comprising 4009 adults were used. Alcohol consumption was assessed by self-report. Serum carbohydrate-deficient transferrin (CDT) was analysed as biomarker for alcohol consumption. Hepatic steatosis was diagnosed by ultrasonography.

RESULTS

Analyses revealed a dose-response relationship between average daily alcohol consumption and hepatic steatosis in men starting with a consumption of 20 g of alcohol per day [adjusted odds ratio (OR) compared to abstainers 1.53; 95% confidence interval (CI) 1.15-2.05]. Using CDT as alternative exposure variable confirmed these results. Binge drinking was associated with hepatic steatosis in men (adjusted OR of binge drinkers compared to nonbinge drinkers 1.36, 95% CI 1.06-1.74). The likelihood of having hepatic steatosis increased in men and women with increasing levels of average daily alcohol consumption in combination with overweight or obesity. Similarly, binge drinking in combination with overweight or obesity enhanced the likelihood of having hepatic steatosis.

CONCLUSIONS

Overweight or obesity substantially enhanced the effect of high levels of average daily alcohol consumption and binge drinking on hepatic steatosis in the present study population. This finding underlines the necessity to screen for multiple risk factors in the prevention of hepatic steatosis.

A systematic review of the prevalence of mildly abnormal liver function tests and associated health outcomes

Liver function tests (LFTs) are commonly performed to investigate asymptomatic individuals or those with nonspecific symptoms. Understanding the prevalence of mildly abnormal LFTs in the general population and the prevalence of liver disease following abnormal LFTs has important implications for the planning of care pathways and the provision of healthcare services. A systematic review of the literature on the prevalence of abnormal LFTs in the general population and their respective health outcomes was conducted. A total of 37 studies reporting data on the prevalence of abnormal LFTs (published between 2000 and 2014) were identified from online database searches or were manually selected from article bibliographies. The prevalence of mildly abnormal LFTs, with one or more abnormal constituents in the LFT, was high at 10-21.7%. The prevalence of severe liver disease within cohorts with abnormal LFTs is relatively low (<5%), and a large proportion of abnormal LFTs remains unexplained. Among individuals with unexplained abnormal LFTs, risk factors include obesity and insulin resistance. Common aetiologies for abnormal LFTs were non-alcohol-related fatty liver disease (NAFLD), followed by alcohol use and viral infections. In addition, normal LFTs do not rule out liver disease. The prevalence of abnormal LFTs depends on the definition and population but is likely to be between 10 and 20% in the general population. Abnormal LFTs are associated with a range of health outcomes but are not necessarily strongly diagnostic of severe liver pathology. Important areas of future research include further studies on the prevalence and predictive ability of LFTs in large, population-representative samples.

Upper limit of normal serum alanine aminotransferase levels in Japanese subjects

AIM

Serum alanine aminotransferase (ALT) is important for screening, diagnosis and management of chronic liver diseases. The incidence of non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH), which is considered a hepatic manifestation of lifestyle-related diseases, is increasing worldwide. However, the upper limit of the normal ALT level has not yet been established because of not excluding many lifestyle-related diseases. The aim of this study was to evaluate the upper limit of normal serum ALT levels in Japanese subjects.

METHODS

We analyzed the serum ALT levels of 11 404 Japanese subjects negative for hepatitis B surface antigen and hepatitis C virus antibody, and who received health check-ups. Lifestyle factors related to ALT levels were determined by multivariate analysis. Subjects with all factors identified by multivariate analysis within the normal range were defined as "healthy" subjects. The 90th percentile of ALT levels in healthy subjects was defined as the upper limit of normal ALT.

RESULTS

Whereas alcohol intake was not a significant factor, the following were independently associated with ALT concentration by multivariate analysis: sex; age; body mass index; waist circumference; concentrations of total cholesterol, high-density lipoprotein cholesterol, triglycerides and fasting blood glucose; and fatty liver on ultrasonography. Healthy subjects consisted of 1462 (21.2%) men and 2046 (45.4%) women, and the 90th percentiles of the ALT levels in the two groups were 29 and 23 IU/L, respectively.

CONCLUSION

The upper limits of normal ALT when considering lifestyle factors in Japanese subjects were 29 IU/L in men and 23 IU/L in women.

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.

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.

Non-invasive separation of alcoholic and non-alcoholic liver disease with predictive modeling

Background & Objective

Currently, a major clinical challenge is to distinguish between chronic liver disease caused by metabolic syndrome (non-alcoholic fatty liver disease, NAFLD) from that caused by long term or excessive alcohol consumption (ALD). The etiology of severe liver disease affects treatment options and priorities for liver transplantation and organ allocation. Thus we compared physiologically similar NAFLD and ALD patients to detect biochemical differences for improved separation of these mechanistically overlapping etiologies.

Methods

In a cohort of 31 NAFLD patients with BMI below 30 and a cohort of ALD patient with (ALDC n = 51) or without cirrhosis (ALDNC n = 51) serum transaminases, cell death markers and (adipo-)cytokines were assessed. Groups were compared with One-way ANOVA and Tukey's correction. Predictive models were built by machine learning techniques.

Results

NAFLD, ALDNC or ALDC patients did not differ in demographic parameters. The ratio of alanine aminotransferase/aspartate aminotransferase - common serum parameters for liver damage - was significantly higher in the NAFLD group compared to both ALD groups (each p<0.0001). Adiponectin and tumor necrosis factor(TNF)-alpha were significantly lower in NAFLD than in ALDNC (p<0.05) or ALDC patients (p<0.0001). Significantly higher serum concentrations of cell death markers, hyaluronic acid, adiponectin, and TNF-alpha (each p<0.0001) were found in ALDC compared to ALDNC. Using machine learning techniques we were able to discern NAFLD and ALDNC (up to an AUC of 0.9118±0.0056) or ALDC and ALDNC (up to an AUC of 0.9846±0.0018), respectively.

Conclusions

Machine learning techniques relying on ALT/AST ratio, adipokines and cytokines distinguish NAFLD and ALD. In addition, severity of ALD may be non-invasively diagnosed via serum cytokine concentrations.

Management of fatty liver disease with the metabolic syndrome

Non-alcoholic fatty liver disease (NAFLD) is the liver disease of this century, increasing in parallel with obesity, insulin resistance and the metabolic syndrome. NAFLD can be seen as a component of the metabolic syndrome, and as such, contributing as a risk factor for cardiovascular disease. In fact, these patients die more often from cardiovascular disease than from direct consequences of liver disease. In this review, we will summarize the data that link NAFLD as a central player in this dysmetabolism, as well as the evidence for appropriate therapy, in order to improve not only liver disease prognosis, but also the overall prognosis and risk of mortality, with particular focus on cardiovascular risk.

Association of glucokinase regulatory gene polymorphisms with risk and severity of non-alcoholic fatty liver disease: an interaction study with adiponutrin gene

BACKGROUND

Recent genome-wide association studies demonstrated an association between single nucleotide polymorphisms (SNPs) on the glucokinase regulatory gene (GCKR) with hepatic steatosis. This study attempted to investigate the association of GCKR rs780094 and rs1260326 with susceptibility to non-alcoholic fatty liver disease (NAFLD) and its severity.

METHODS

The genotypes were assessed on 144 histologically confirmed NAFLD patients and 198 controls using a Sequenom MassARRAY platform.

RESULTS

The GCKR rs1260326 and rs780094 allele T were associated with susceptibility to NAFLD (OR 1.49, 95 % CI 1.09-2.05, p = 0.012; and OR 1.51, 95 % CI 1.09-2.09, p = 0.013, respectively), non-alcoholic steatohepatitis (NASH) (OR 1.55, 95 % CI 1.10-2.17, p = 0.013; and OR 1.56, 95 % CI 1.10-2.20, p = 0.012, respectively) and NASH with significant fibrosis (OR 1.50, 95 % CI 1.01-2.21, p = 0.044; and OR 1.52, 95 % CI 1.03-2.26, p = 0.038, respectively). Following stratification by ethnicity, significant association was seen in Indian patients between the two SNPs and susceptibility to NAFLD (OR 2.64, 95 % CI 1.28-5.43, p = 0.009; and OR 4.35, 95 % CI 1.93-9.81, p < 0.0001, respectively). The joint effect of GCKR with adiponutrin rs738409 indicated greatly increased the risk of NAFLD (OR 4.14, 95 % CI 1.41-12.18, p = 0.010). Histological data showed significant association of GCKR rs1260326 with high steatosis grade (OR 1.76, 95 % CI 1.08-2.85, p = 0.04).

CONCLUSION

This study suggests that risk allele T of the GCKR rs780094 and rs1260326 is associated with predisposition to NAFLD and NASH with significant fibrosis. The GCKR and PNPLA3 genes interact to result in increased susceptibility to NAFLD.

Genome-wide analysis of copy number variation identifies candidate gene loci associated with the progression of non-alcoholic fatty liver disease

Between 10 and 25% of individuals with non-alcoholic fatty liver disease (NAFLD) develop hepatic fibrosis leading to cirrhosis and hepatocellular carcinoma (HCC). To investigate the molecular basis of disease progression, we performed a genome-wide analysis of copy number variation (CNV) in a total of 49 patients with NAFLD [10 simple steatosis and 39 non-alcoholic steatohepatitis (NASH)] and 49 matched controls using high-density comparative genomic hybridization (CGH) microarrays. A total of 11 CNVs were found to be unique to individuals with simple steatosis, whilst 22 were common between simple steatosis and NASH, and 224 were unique to NASH. We postulated that these CNVs could be involved in the pathogenesis of NAFLD progression. After stringent filtering, we identified four rare and/or novel CNVs that may influence the pathogenesis of NASH. Two of these CNVs, located at 13q12.11 and 12q13.2 respectively, harbour the exportin 4 (XPO4) and phosphodiesterase 1B (PDE1B) genes which are already known to be involved in the etiology of liver cirrhosis and HCC. Cross-comparison of the genes located at these four CNV loci with genes already known to be associated with NAFLD yielded a set of genes associated with shared biological processes including cell death, the key process involved in 'second hit' hepatic injury. To our knowledge, this pilot study is the first to provide CNV information of potential relevance to the NAFLD spectrum. These data could prove invaluable in predicting patients at risk of developing NAFLD and more importantly, those who will subsequently progress to NASH.

Effect of lifetime alcohol consumption on the histological severity of non-alcoholic fatty liver disease

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is defined based on recent alcohol consumption; however, remote or lifetime alcohol consumption is not taken into account. It is not known whether lifetime alcohol consumption contributes to the severity of disease in patients with NAFLD. To determine the effect of lifetime alcohol consumption on the histological severity in patients with NAFLD.

PATIENTS & METHODS

Adults >18 years of age with presumed NAFLD and alcohol consumption <40 g/week were enrolled. Lifetime alcohol consumption was determined using a questionnaire. Patients with a history of long-term alcohol abuse or dependence were excluded. A liver biopsy was reviewed by a single pathologist in a blinded fashion. Demographic, clinical and histological findings were compared in those who had regular alcohol consumption and those who did not.

RESULTS

A total of 77 patients had fatty liver on biopsy. Fifty-two patients had a history of regular alcohol consumption. The median lifetime cumulative alcohol intake was 24 gram-years. On multivariable analysis, increasing age (OR 1.07, 95% CI 1.01-1.14) was associated with severe liver disease, whereas alcohol consumption of ≥24 gram-years was associated with less severe disease (OR 0.26, 95% CI 0.07-0.97, P = 0.04). Patients who continued to consume alcohol or had been abstinent for ≤1 year had less severe disease.

CONCLUSION

Some degree of regular alcohol consumption over the course of a lifetime compared to minimal intake appears to have a protective effect on the histological severity of liver disease among patients with strictly defined NAFLD.

Alanine aminotransferase-old biomarker and new concept: a review

Measurement of serum alanine aminotransferase (ALT) is a common, readily available, and inexpensive laboratory assay in clinical practice. ALT activity is not only measured to detect liver disease, but also to monitor overall health. ALT activity is influenced by various factors, including viral hepatitis, alcohol consumption, and medication. Recently, the impact of metabolic abnormalities on ALT variation has raised concern due to the worldwide obesity epidemic. The normal ranges for ALT have been updated and validated considering the metabolic covariates in the various ethnic districts. The interaction between metabolic and demographic factors on ALT variation has also been discussed in previous studies. In addition, an extremely low ALT value might reflect the process of aging, and frailty in older adults has been raised as another clinically significant feature of this enzyme, to be followed with additional epidemiologic investigation. Timely updated, comprehensive, and systematic introduction of ALT activity is necessary to aid clinicians make better use of this enzyme.

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.

Impact of leptin receptor gene variants on risk of non-alcoholic fatty liver disease and its interaction with adiponutrin gene

BACKGROUND AND AIM

Genetic polymorphism has been implicated as a factor for the occurrence of non-alcoholic fatty liver disease (NAFLD). This study attempted to assess whether polymorphisms in the leptin receptor (LEPR) gene and its combined effect with patatin-like phospholipase domain-containing protein 3 (PNPLA3/adiponutrin) are associated with risk of NAFLD.

METHODS

A total of 144 biopsy-proven NAFLD and 198 controls were genotyped using the Sequenom MassARRAY platform.

RESULTS

We observed a significant association between the LEPR rs1137100 and rs1137101 with susceptibility to NAFLD (odds ratio [OR] 1.64, 95% confidence interval [CI] 1.18-2.28, P = 0.003; and OR 1.61, 95% CI 1.11-2.34, P = 0.013, respectively) and to non-alcoholic steatohepatitis (OR 1.49, 95% CI 1.05-2.12, P = 0.026; and OR 1.57, 95% CI 1.05-2.35, P = 0.029, respectively). The LEPR rs1137100 is also associated with simple steatosis (OR 2.27, 95% CI 1.27-4.08, P = 0.006). Analysis of gene-gene interaction revealed a strong interaction between the LEPR and PNPLA3 genes (empirical P = 0.001). The joint effect of LEPR and PNPLA3 greatly exacerbated the risk of NAFLD (OR 3.73, 95% CI 1.84-7.55, P < 0.0001). The G allele of rs1137100 is associated with lower fibrosis score (OR 0.47, 95% CI 0.28-0.78, P = 0.001).

CONCLUSIONS

We report an association between variants of LEPR rs1137100 and rs1137101 with risk of NAFLD. This study suggests that rs1137100, specifically the G allele, is associated with a less severe form of liver disease in patients with NAFLD. The interaction between LEPR and PNPLA3 genes showed increased risk of NAFLD compared to either gene alone.

Upper limit of normal for alanine aminotransferase: quo vadis?

Several studies suggest that a substantial number of patients with normal serum alanine aminotransferase (ALT) levels, defined by current thresholds, have ongoing hepatic necro-inflammation and fibrosis, and are at risk of liver disease progression. A major problem lies in the definition of normality. The current upper limit of normal (ULN) for ALT was established in the 1980s when reference populations were likely to include many persons with hepatitis C virus infection and nonalcoholic fatty liver disease. Because ALT may be influenced, not only by liver disease, but also by other medical conditions, changing lifestyle factors and demographic determinants, the current ALT ULN threshold has recently been challenged. This review not only highlights current evidence on why and how ALT ULN should be redefined, but also discusses the current concerns about updating the ULN threshold for ALT.

Susceptibility and gene interaction study of the angiotensin II type 1 receptor (AGTR1) gene polymorphisms with non-alcoholic fatty liver disease in a multi-ethnic population

Angiotensin II type 1 receptor (AGTR1) has been reported to play a fibrogenic role in non-alcoholic fatty liver disease (NAFLD). In this study, five variants of the AGTR1 gene (rs3772622, rs3772627, rs3772630, rs3772633, and rs2276736) were examined for their association with susceptibility to NAFLD. Subjects made up of 144 biopsy-proven NAFLD patients and 198 controls were genotyped using TaqMan assays. The liver biopsy specimens were histologically graded and scored according to the method of Brunt. Single locus analysis in pooled subjects revealed no association between each of the five variants with susceptibility to NAFLD. In the Indian ethnic group, the rs2276736, rs3772630 and rs3772627 appear to be protective against NAFLD (p = 0.010, p = 0.016 and p = 0.026, respectively). Haplotype ACGCA is shown to be protective against NAFLD for the Indian ethnic subgroup (p = 0.03). Gene-gene interaction between the AGTR1 gene and the patatin-like phospholipase domain-containing 3 (PNPLA3) gene, which we previously reported as associated with NAFLD in this sample, showed a strong interaction between AGTR1 (rs3772627), AGTRI (rs3772630) and PNPLA3 (rs738409) polymorphisms on NAFLD susceptibility (p = 0.007). Further analysis of the NAFLD patients revealed that the G allele of the AGTR1 rs3772622 is associated with increased fibrosis score (p = 0.003). This is the first study that replicates an association between AGTR1 polymorphism and NAFLD, with further details in histological features of NAFLD. There is lack of evidence to suggest an association between any of the five variants of the AGTR1 gene and NAFLD in the Malays and Chinese. In the Indians, the rs2276736, rs3772630 and rs3772627 appear to protect against NAFLD. We report novel findings of an association between the G allele of the rs3772622 with occurrence of fibrosis and of the gene-gene interaction between AGTR1gene and the much-studied PNPLA3 gene.

Elevated serum uric acid levels are associated with non-alcoholic fatty liver disease independently of metabolic syndrome features in the United States: Liver ultrasound data from the National Health and Nutrition Examination Survey

OBJECTIVE

Experimental and observational studies suggest a role for uric acid in non-alcoholic fatty liver disease (NAFLD). We examined the association between serum uric acid levels and NAFLD in a large population-based study from the United States.

MATERIALS/METHODS

A cross-sectional analysis of 10,732 nondiabetic adults who participated in the National Health and Nutrition Examination Survey 1988-1994. Sex specific uric acid quartiles were defined: ≤5.2, 5.3-6.0, 6.1-6.9, and >6.9mg/dL for men and ≤3.7, 3.8-4.5, 4.6-5.3, and >5.3mg/dL for women. NAFLD presence and severity were defined by ultrasonographic detection of steatosis in the absence of other liver diseases. We modeled the probability that more severe NAFLD would be associated with the highest quartiles of uric acid.

RESULTS

Compared to the 1st quartile, the odds ratio for NAFLD was 1.79 (95% C.I. 1.49-2.15, p<0.001) and 3.14 (95% C.I. 2.63-3.75, p<0.001) for the 3rd and 4th quartiles, respectively. After adjusting for demographics, hypertension, waist circumference, triglycerides, high-density lipoprotein-cholesterol, homeostasis model assessment-estimated insulin resistance, estimated glomerular filtration rate, and aspartate aminotransferase, uric acid (4th quartile) was significantly associated with NAFLD (odds ratio 1.43; 95% C.I. 1.16-1.76, p<0.001). Positive parameter estimates suggest increasing uric acid is associated with greater severity of NAFLD.

CONCLUSIONS

Elevated uric acid level is independently associated with ultrasound-diagnosed NAFLD in a nationally representative sample of United States nondiabetic adults. Increasing uric acid is associated with increasing severity of NAFLD on ultrasonography. These findings warrant further studies on the role of uric acid in NAFLD.

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.

Toll-like receptors in liver disease

Activation of inflammatory signaling pathways is of central importance in the pathogenesis of alcoholic liver disease (ALD) and nonalcoholic steatohepatitis (NASH). Recent studies demonstrated that Toll-like receptors, the sensors of microbial and endogenous danger signals, are expressed and activated in innate immune cells as well as in parenchymal cells in the liver and thereby contribute to ALD and NASH. In this review, we emphasize the importance of gut-derived endotoxin and its recognition by TLR4 in the liver. The significance of TLR-induced intracellular signaling pathways and cytokine production as well as the contribution of individual cell types to the inflammation is evaluated. The contribution of TLR signaling to the induction of liver fibrosis and to the progression of liver pathology mediated by viral pathogens is reviewed in the context of ALD and NASH.

Upper reference limits for aminotransferase activities and the prevalence of elevated aminotransferase activities in a Korean population

BACKGROUND

Despite suggestions to lower the upper reference limits (URL) for aminotransferase activities to increase the detection of liver disease, there is no generally accepted URL in the general Korean population.

METHODS

We set the URL for alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities at the 97.5th percentile in a population at low risk for liver disease (n=3316; negative HBs antigen, low alcohol intake, normal waist circumference, normal lipid or carbohydrate metabolism, and absence of medication use) derived from the 2007 to 2009 Korean National Health and Nutrition Examination Survey (KNHANES; n=16,608).

RESULTS

The URLs for ALT activity were 53 IU/L for men and 30 IU/L for women, and the corresponding limits for AST activity were 37 IU/L for men and 29 IU/L for women. The age-adjusted prevalence of the elevated ALT activity was 8.6% [95% confidence interval (CI), 8.2%-9.1%] in the 2007 to 2009 KNHANES and 6.9% (95% CI, 6.3%-7.5%) in the 2001 KNHANES, a relative increase of 24.6% (P<0.05). This increase was concentrated among those aged 20 to 29, with a relative increase of 66.7%, and those aged 30 to 39, with a relative increase of 54.4%. There was no significant change in the prevalence of elevated AST activity.

CONCLUSIONS

The URL for ALT activity among the general Korean population is clearly higher than recently proposed thresholds. The trajectory of the increasing prevalence of elevated ALT activity heralds an increased burden of chronic liver disease in the future Korean population.

The interaction of rs738409, obesity, and alcohol: a population-based autopsy study

OBJECTIVES

The objective of this study was to access the prevalence of alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) histology in the general population, which had been otherwise difficult to access because of inherent misclassification bias in surrogate marker studies and referral bias in patient case series. The interaction among rs738409, obesity, and alcohol remains controversial. This population-based autopsy study investigated the histological prevalence of ALD and NAFLD, and interactions among rs738409, obesity, and alcoholism.

METHODS

A total of 170 alcoholic and 235 nonalcoholic cases were selected from 1,034 adult car accident autopsies in 17 Kansas and Missouri counties from 2000 to 2010. The nonalcoholic group had undetectable blood alcohol concentration, while the alcoholic group had a blood alcohol concentration ≥0.08%.

RESULTS

The age-standardized prevalences of hepatic steatosis, steatohepatitis, and advanced fibrosis were 56, 6, and 18% among alcoholics and 36, 4, and 6% in nonalcoholics, respectively. The interaction terms among alcohol, body mass index (BMI), and genotype were not significant. rs738409 GC or GG genotype was associated with 1.9-fold odds (95% confidence interval (CI), 1.2-2.9) of a higher NAFLD Activity Score (NAS). Alcohol had 3.5-fold odds (95% CI, 2.0-5.9), while every 5-unit increase in BMI had 1.9-fold odds (95% CI, 1.7-2.5). A negative interaction between alcohol and BMI towards fibrosis had been observed (P=0.045). Every 5-unit increase in BMI had 2.2-fold odds (95% CI, 1.5-2.5) of fibrosis among nonalcoholics, but not in alcoholics.

CONCLUSIONS

This study assessed the prevalence of fatty liver histology in the general population from an autopsy study perspective. The finding of an additive interaction among rs738409, obesity, and alcohol towards NAS may be useful in targeting preventative care to patients at highest risk for ALD. The negative interaction between alcohol and obesity towards fibrosis supported previous findings and suggests the need for future research to explore potential mechanisms that may improve treatment of nonalcoholic steatohepatitis-related fibrosis.

Reducing the load: the evolution and management of obesity and nonalcoholic steatohepatitis before liver transplantation

1. Obesity is common in patients with end-stage liver disease of any cause. 2. Obesity is associated with comorbidities that can affect liver transplant candidacy, such as metabolic syndrome (diabetes, hyperlipidemia, and hypertension), cardiovascular disease, pulmonary disorders (related to obstructive sleep apnea), renal dysfunction, and malignancies. 3. Nonalcoholic steatohepatitis is the only indication for transplantation that is increasing in frequency, and it may soon become the leading indication. 4. There is no set body mass index above which liver transplantation is contraindicated. Transplant candidacy and outcomes depend on the cumulative comorbidities of the individual patient. 5. Weight loss is an important component of metabolic syndrome management and is recommended before liver transplantation. 6. Bariatric surgery may be considered in carefully selected patients with well-compensated cirrhosis but is not recommended in patients with decompensated cirrhosis.

Modest alcohol consumption is associated with decreased prevalence of steatohepatitis in patients with non-alcoholic fatty liver disease (NAFLD)

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is a cardiovascular risk factor. Although modest alcohol consumption may reduce the risk for cardiovascular mortality, whether patients with NAFLD should be allowed modest alcohol consumption remains an important unaddressed issue. We aimed to evaluate the association between modest alcohol drinking and non-alcoholic steatohepatitis (NASH), among subjects with NAFLD.

METHODS

In a cross-sectional analysis of adult participants in the NIH NASH Clinical Research Network, only modest or non-drinkers were included: participants identified as (1) drinking >20 g/day, (2) binge drinkers, or (3) non-drinkers with previous alcohol consumption were excluded. The odds of having a histological diagnosis of NASH and other histological features of NAFLD were analyzed using multiple ordinal logistic regression.

RESULTS

The analysis included 251 lifetime non-drinkers and 331 modest drinkers. Modest drinkers compared to non-drinkers had lower odds of having a diagnosis of NASH (summary odds ratio 0.56, 95% CI 0.39-0.84, p=0.002). The odds of NASH decreased as the frequency of alcohol consumption increased within the range of modest consumption. Modest drinkers also had significantly lower odds for fibrosis (OR 0.56 95% CI 0.41-0.77) and ballooning hepatocellular injury (OR 0.66 95% CI 0.48-0.92) than lifetime non-drinkers.

CONCLUSIONS

In a large, well-characterized population with biopsy-proven NAFLD, modest alcohol consumption was associated with lesser degree of severity as determined by lower odds of the key features that comprise a diagnosis of steatohepatitis, as well as fibrosis. These findings demonstrate the need for prospective studies and a coordinated consensus on alcohol consumption recommendations in NAFLD.

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.

Calorie and alcohol consumption in nonalcoholic fatty liver disease

OBJECTIVES AND METHODS

Most definitions of nonalcoholic fatty liver disease (NAFLD) allow some intake of alcohol but little attention has been paid to the possible contribution of alcohol-derived calories in the overall daily intake. The aim of the present study was to determine whether, in a group of 144 patients referred to liver outpatients with NAFLD, a more structured questioning of dietary habits and alcohol consumption would provide better information on alcohol-derived and dietary-derived calorie intake and the relationship with the BMI.

RESULTS

Both food intake and calories resulting from alcohol ingestion were frequently underestimated as was the percentage of patients who were drinking excessively (>30 U a week), which was surprisingly high at 40%. The substantial calorie intake resulting from alcohol consumption in this group was associated with a reduction in dietary calorie intake, so that the total daily calorie intake remained similar to those with low-to-moderate or no alcohol consumption. The findings also showed that the BMI, although still elevated, was significantly reduced in those drinking heavily compared with low and nondrinkers.

CONCLUSION

Patients with NAFLD can have substantially higher levels of alcohol consumption than usually recognized. The additional calorie intake resulting from this is to some extent balanced by a reduction in dietary calorie intake with less elevation in BMI, and a clear distinction from an alcohol-induced steatosis may be difficult.

Impact of current treatments on liver disease, glucose metabolism and cardiovascular risk in non-alcoholic fatty liver disease (NAFLD): a systematic review and meta-analysis of randomised trials

AIMS/HYPOTHESIS

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum ranging from simple steatosis to non-alcoholic steatohepatitis (NASH): NAFLD causes an increased risk of cardiovascular disease, diabetes and liver-related complications (the latter confined to NASH). The effect of proposed treatments on liver disease, glucose metabolism and cardiovascular risk in NAFLD is unknown. We reviewed the evidence for the management of liver disease and cardio-metabolic risk in NAFLD.

METHODS

Publications through November 2011 were systematically reviewed by two authors. Outcomes evaluated though standard methods were: histological/radiological/biochemical features of NAFLD, variables of glucose metabolism and cardiovascular risk factors. Seventy-eight randomised trials were included (38 in NASH, 40 in NAFLD): 41% assessed post-treatment histology, 71% assessed glucose metabolism and 88% assessed cardiovascular risk factors. Lifestyle intervention, thiazolidinediones, metformin and antioxidants were most extensively evaluated.

RESULTS

Lifestyle-induced weight loss was safe and improved cardio-metabolic risk profile; a weight loss ≥7% improved histological disease activity, but was achieved by <50% patients. Statins and polyunsaturated fatty acids improved steatosis, but their effects on liver histology are unknown. Thiazolidinediones improved histological disease activity, glucose, lipid and inflammatory variables and delayed fibrosis progression. Pioglitazone also improved blood pressure. Weight gain (up to 4.8%) was common. Antioxidants yielded mixed histological results: vitamin E improved histological disease activity when administered for 2 years, but increased insulin resistance and plasma triacylglycerols.

CONCLUSIONS/INTERPRETATION

Weight loss is safe, and improves liver histology and cardio-metabolic profile. For patients not responding to lifestyle intervention, pioglitazone improves histological disease activity, slows fibrosis progression and extensively ameliorates cardio-metabolic endpoints. Further randomised controlled trials (RCTs) of adequate size and duration will assess long-term safety and efficacy of proposed treatments on clinical outcomes.

A multi-ethnic study of a PNPLA3 gene variant and its association with disease severity in non-alcoholic fatty liver disease

The adiponutrin (PNPLA3) rs738409 polymorphism has been found to be associated with susceptibility to non-alcoholic fatty liver disease (NAFLD) in various cohorts. We further investigated the association of this polymorphism with non-alcoholic steatohepatitis (NASH) severity and with histological features of NAFLD. A total of 144 biopsy-proven NAFLD patients and 198 controls were genotyped for PNPLA3 gene polymorphism (rs738409 C>G). The biopsy specimens were histologically graded by a qualified pathologist. We observed an association of G allele with susceptibility to NAFLD in the pooled subjects (OR 2.34, 95% CI 1.69–3.24, p < 0.0001), and following stratification, in each of the three ethnic subgroups, namely Chinese, Indian and Malay (OR 1.94, 95% CI 1.12–3.37, p = 0.018; OR 3.51, 95% CI 1.69–7.26, p = 0.001 and OR 2.05, 95% CI 1.25–3.35, p = 0.005, respectively). The G allele is associated with susceptibility to NASH (OR 2.64, 95% CI 1.85–3.75, p < 0.0001), with NASH severity (OR 1.85, 95% CI 1.05–3.26, p = 0.035) and with presence of fibrosis (OR 1.95, 95% CI 1.17–3.26, p = 0.013) but not with simple steatosis nor with other histological parameters. Although the serum triglyceride level is significantly higher in NAFLD patients compared to controls, the G allele is associated with decreased level of triglycerides (p = 0.029) in the NAFLD patients. Overall, the rs738409 G allele is associated with severity of NASH and occurence of fibrosis in patients with NAFLD.

Liver enzymes: interaction analysis of smoking with alcohol consumption or BMI, comparing AST and ALT to γ-GT

BACKGROUND

A detrimental interaction between smoking and alcohol consumption with respect serum γ-glutamyltransferase (γ-GT) has recently been described. The underlying mechanisms remain unknown. The present work aimed to provide further insights by examining similar interactions pertaining to aspartate and alanine transaminase (AST, ALT), routine liver markers less prone to enzyme induction.

METHODOLOGY/PRINCIPAL FINDINGS

The present cross-sectional analysis was based on records from routine occupational health examinations of 15,281 male employees predominantly of the construction industry, conducted from 1986 to 1992 in Southern Germany. Associations of smoking intensity with log-transformed activities of γ-GT, AST, and ALT were examined in regression models adjusted for potential confounders and including an interaction of smoking with alcohol consumption or body mass index (BMI). Statistically significant interactions of smoking were observed with both alcohol consumption (AST and ALT, each with P<0.0001) and BMI (AST only, P<0.0001). The interactions all were in the same directions as for γ-GT, i.e. synergistic with alcohol and opposite with BMI.

CONCLUSION

The patterns of interaction between smoking and alcohol consumption or BMI with respect to AST and ALT resembled those observed for γ-GT. This renders enzyme induction a less probable mechanism for these associations, whereas it might implicate exacerbated hepatocellular vulnerability and injury.

Multiple health behaviors and serum hepatic enzymes among US adults with obesity

INTRODUCTION

This study was to examine the cumulative number and clustering patterns of low-risk health behaviors (i.e., not currently smoking, not excessive drinking, and physically active) associated with elevation of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyltransferase (GGT) among adults with obesity in the United States.

METHODS

We estimated the age-adjusted prevalence of elevated ALT, AST, and GGT from 4547 adults with obesity aged ≥ 20 years who participated in the 2005-2008 National Health and Nutrition Examination Survey. The associations between the cumulative number or clustering patterns of low-risk health behaviors and measures of serum ALT, AST, and GGT were assessed using multivariate regression models.

RESULTS

Adult men who reported having three low-risk health behaviors were 62%, 39%, and 48% less likely to have elevated serum ALT, AST, and GGT, respectively; adult women were 56% and 73% less likely to have elevated serum AST and GGT, respectively, when compared to their respective counterparts who reported having none of the low-risk health behaviors.

CONCLUSIONS

The findings of this study indicate that, among adults with obesity, having multiple low-risk health behaviors is associated with decreased likelihoods of elevated hepatic enzymes, including ALT in men, AST and GGT in both men and women.

Synergistic steatohepatitis by moderate obesity and alcohol in mice despite increased adiponectin and p-AMPK

BACKGROUND & AIMS

Mechanisms underlying synergistic liver injury caused by alcohol and obesity are not clear. We have produced a mouse model of synergistic steatohepatitis by recapitulating the natural history of the synergism seen in patients for mechanistic studies.

METHODS

Moderate obesity was induced in mice by 170% overnutrition in calories using intragastric overfeeding of high fat diet. Alcohol (low or high dose) was then co-administrated to determine its effects.

RESULTS

Moderate obesity plus alcohol intake causes synergistic steatohepatitis in an alcohol dose-dependent manner. A heightened synergism is observed when a high alcohol dose (32g/kg/d) is used, resulting in plasma ALT reaching 392±28U/L, severe steatohepatitis with pericellular fibrosis, marked M1 macrophage activation, a 40-fold induction of iNos, and intensified nitrosative stress in the liver. Hepatic expression of genes for mitochondrial biogenesis and metabolism are significantly downregulated, and hepatic ATP level is decreased. Synergistic ER stress evident by elevated XBP-1, GRP78 and CHOP is accompanied by hyperhomocysteinemia. Despite increased caspase 3/7 cleavage, their activities are decreased in a redox-dependent manner. Neither increased PARP cleavage nor TUNEL positive hepatocytes are found, suggesting a shift of apoptosis to necrosis. Surprisingly, the synergism mice have increased plasma adiponectin and hepatic p-AMPK, but adiponectin resistance is shown downstream of p-AMPK.

CONCLUSIONS

Nitrosative stress mediated by M1 macrophage activation, adiponectin resistance, and accentuated ER and mitochondrial stress underlie potential mechanisms for synergistic steatohepatitis caused by moderate obesity and alcohol.

Elevated serum liver enzymes and fatty liver changes associated with long driving among taxi drivers

BACKGROUND

Previous studies suggested increased morbidities and mortalities of liver diseases in drivers.

METHODS

To examine whether driving (monthly driving distance; tenure) is associated with elevated alanine aminotransferase (ALT), aspartate aminotransferase (AST), or chronic fatty liver (FL) changes, we performed a cross-sectional, secondary analysis of the Taxi Drivers' Health Study (n = 1,355), adjusting for clinical, demographic, and lifestyle factors.

RESULTS

Prevalence of elevated ALT, elevated AST, and fatty liver changes were 22.0%, 5.1%, and 9.3%, respectively. Driving distance had a positive association with elevated ALT with a prevalence ratio of 1.35 (95% CI: 0.98, 1.89) comparing the highest versus lowest driving quartile. This association differed by alcohol use, with a corresponding prevalence ratio of 2.08 (95% CI: 1.30, 3.33) among "past/current" drinkers but no association among "never" drinkers. Similar patterns were found for AST, but estimates were less stable. We found a curvilinear response pattern for fatty liver changes; prevalence first increased with years as a taxi driver and then receded in the highest ranges of driving tenure, regardless of the alcohol history.

CONCLUSIONS

Our results provide evidence that long driving is associated with both short-term and chronic liver insults, although alcohol use appears to modify this putative effect.

Relationship among alcohol intake, body fat, and physical activity: a population-based study

OBJECTIVES

Aside from fat, ethanol is the macronutrient with the greatest energy density. Whether the energy derived from ethanol affects body composition and fat mass is debatable. We investigated the relationship of alcohol intake, body composition, and physical activity in the U.S. population by using data from the Third National Health and Nutrition Examination Survey (NHANES III).

METHODS

A total of 10,550 subjects met eligibility criteria and constituted our study cohort. Estimated percent body fat and resting metabolic rate were calculated on the basis of the sum of the skinfolds. Multivariate regression analyses were performed accounting for the study sampling weight.

RESULTS

In both sexes, moderate and hazardous alcohol drinkers were younger (p < .05) and had significantly lower body mass index (p < 0.01) and body weight (p < 0.01) than non-drinkers. Those with hazardous alcohol consumption participated in significantly less physical activity compared with those with no alcohol use and moderate drinkers in both sexes. Women had significantly greater percent body fat than men. In multivariate linear regression analyses, the levels of alcohol consumption were found to be an independent predictor associated with lower percent body fat only in male subjects.

CONCLUSIONS

Our results showed that alcoholics are habitually less active and that alcohol drinking is an independent predictor of lower percent body fat, especially in male alcoholics.

Risk factors for serum alanine aminotransferase elevation: A cross-sectional study of healthy adult males in Tokyo, Japan

BACKGROUND

Liver-protective effects of light-to-moderate alcohol consumption have been suggested.

AIMS

To determine predictors of ALT elevation in asymptomatic subjects with and without ultrasonographical evidence of fatty liver.

METHODS

Cross-sectional survey of 9703 healthy males. Exclusion criteria were HBV or HCV infection, any use of hepatotoxic medication, history of alcohol abuse, chronic renal or hepatic failure, or treatment for metabolic disorders. Presence of fatty liver was evaluated by ultrasonography; visceral adipose tissue (VAT) was measured by computed tomography (CT).

RESULTS

7148 males (mean age, 50.3±7.8 years) were included; 2406 (33.7%) had fatty liver at ultrasonography. ALT was elevated in 163 (3.4%) and 554 subjects (23.0%) of fatty liver-negative and fatty liver-positive subgroups, respectively. Light (40-140g/week) alcohol consumption was significantly and independently associated with reduced prevalence of ALT elevation in the fatty liver-negative subgroup (OR=0.568, 95% CI=0.342-0.943, P=0.029). ALT elevation was significantly related to age, VAT, high-density lipoprotein cholesterol (HDL-C) and triglyceride (TG) in the fatty liver-negative subgroup.

CONCLUSION

Light alcohol consumption is not associated with serum ALT elevation in the Japanese male population. Metabolic syndrome factors are significantly associated with prevalence of ALT elevation, irrespective of the presence of fatty liver.

Biomarkers of alcohol consumption and related liver disease

Abstract Alcohol abuse is a major cause of abnormal liver function throughout the world. While measurements of liver enzyme activities (GGT, ALT, AST) are important screening tools for detecting liver disease, due to lack of ethanol-specificity and inconsistencies regarding the definitions of significant alcohol consumption, several other blood tests are usually needed to exclude competing and co-existing causes of abnormal liver function. Information on the specific role of ethanol consumption behind hepatotoxicity may be obtained through measurements of blood ethanol and its specific metabolites (ethyl glucuronide, phosphatidylethanol, protein-acetaldehyde condensates and associated autoimmune responses). Recent studies have indicated that being overweight is another increasingly common cause of abnormal liver enzyme levels and adiposity may also increase the impact of ethanol consumption on liver pathology. Interestingly, increased liver enzyme activities in circulation may reflect not only hepatic function but can also serve as indicators of general health and the status of oxidative stress in vivo. ALT and GGT activities predict insulin resistance, metabolic syndrome, mortality from coronary heart diseases and even mortality from all causes. If the upper reference limits for liver enzyme activities were defined based on the data obtained from normal weight abstainers, the clinical value of liver enzyme measurements as screening tools and in patient follow-up could be significantly improved.

Relationship between alcohol drinking and aspartate aminotransferase:alanine aminotransferase (AST:ALT) ratio, mean corpuscular volume (MCV), gamma-glutamyl transpeptidase (GGT), and apolipoprotein A1 and B in the U.S. population

OBJECTIVE

The misuse of alcohol, even at levels just above two drinks per day, is a public health problem, but identifying patients with this potentially unhealthy drinking is hindered by the lack of tests. Several blood tests, such as those testing for gamma-glutamyl transpeptidase (GGT) or mean corpuscular volume (MCV), are among the commonly used markers to identify very heavy drinking, but combinations of these markers have rarely been tested in lighter drinkers. We examined the relationship between alcohol drinking and the levels of these markers in a national population-based study composed primarily of lighter drinkers.

METHOD

Data were analyzed from 8,708 adult participants in the third U.S. National Health and Nutrition Examination Survey after excluding subjects with iron overload; with hepatitis B and C; who were pregnant; and who were taking prescription drugs such as phenytoin (Dilantin), barbiturates, and hydroxyurea (Droxia and Hydrea). The relationship between the amount of alcohol drinking and GGT, aspartate aminotransferase:alanine aminotransferase ratio, MCV of erythrocytes, and apolipoprotein A1 and B were analyzed and adjusted for potential liver injury risk factors.

RESULTS

The prevalence of unhealthy alcohol drinking (defined as consumption of more than two standard drinks per day) was 6.7%. Heavier drinkers tended to be younger and reported an average of 4.2 drinks per day. When tested alone or in combination, the sensitivity and positive predictive values for these blood tests were too low to be clinically useful in identifying the subjects in the heavier drinking category.

CONCLUSIONS

In this large, national, population-based study, the markers of heavy drinking studied here, either alone or in combination, did not appear to be useful in identifying unhealthy drinking. More work is needed to find the novel marker(s) associated with risky alcohol drinking.