Effect of ALDH2 and CYP2E1 gene polymorphisms on drinking behavior and alcoholic liver disease in Japanese male workers

ALDH2 p.E504K Variation and Sex Are Major Factors Associated with Current and Quitting Alcohol Drinking in Japanese Oldest Old

This study identified the factors associated with current and quitting alcohol drinking in the Oldest Old to better understand the associated factors and mechanisms underlying drinking behaviors in this age group. Results of a questionnaire for drinking behavior in 1015 Japanese Oldest Old citizens aged 85 to 89 years revealed that 56.0% of men and 24.0% of women were current drinkers. A genome-wide association study revealed that the rs671 G > A variation, which corresponds to the aldehyde dehydrogenase 2 (ALDH2) p.E504K missense variant, was significantly associated with current drinking (odds ratio: 3.8, p = 3.33 × 10^-31). Variable selection with 41 factors and multivariate regression logistic analysis for current drinking indicated that the rs671 genotype and sex were the most significant factors in the Oldest Old. Further analysis revealed that the rs671 genotype, alcohol-associated biomarkers, a history of heart or kidney disease, and frailty score are factors associated with quitting drinking in the Oldest Old men, whereas smoking history, walking time, and depression score were factors associated with quitting drinking in the Oldest Old women. These results indicate that the ALDH2 p.E504K variation is a major factor associated with current and quitting drinking in the Japanese Oldest Old.

Moderate alcohol consumption is associated with impaired insulin secretion and fasting glucose in non-obese non-diabetic men

AIMS/INTRODUCTION

A low insulin secretion capacity has been implicated in the high prevalence of non-obese diabetes in East Asians. As alcohol consumption alters insulin and glucose metabolism, we tested the hypothesis that alcohol consumption contributes to impaired insulin secretion and glucose intolerance in lean/normal-weight non-diabetic Japanese men.

MATERIALS AND METHODS

This cross-sectional study was undertaken among the residents of Shika town, Japan, between 2011 and 2017. A total of 402 non-diabetic men, including participants with normal fasting plasma glucose (FPG) and impaired FPG (FPG 5.6-6.9 mmol/L), and aged ≥40 years, were examined. FPG, the homeostasis model assessment of insulin secretion capacity (HOMA-B) and alcohol consumption were evaluated and compared between the body mass index (BMI) <25 and BMI ≥25 groups.

RESULTS

HOMA-B levels were lower in the BMI <25 group than in the BMI ≥25 group. Alcohol consumption correlated with a low HOMA-B level regardless of BMI, and, thus, the HOMA-B levels of alcohol drinkers were significantly lower in the BMI <25 group. A multivariable logistic regression analysis showed that alcohol consumption, even light-to-moderate consumption (1-25 g/day), was associated with significantly low levels of HOMA-B and impaired FPG in the BMI <25 group. Among participants with impaired FPG, a low level of HOMA-B was observed in alcohol drinkers, but not in non-drinkers. In contrast, light-to-moderate alcohol consumption was not related to HOMA-B or FPG in the BMI ≥25-group.

CONCLUSION

Alcohol consumption, even a small amount, might contribute to reductions in HOMA-B levels and impaired FPG in lean/normal-weight Japanese men.

Hepatic injury and inflammation alter ethanol metabolism and drinking behavior

While liver injury is commonly associated with excessive alcohol consumption, how liver injury affects alcohol metabolism and drinking preference remains unclear. To answer these questions, we measured the expression and activity of alcohol dehydrogenase 1 (ADH1) and acetaldehyde dehydrogenase 2 (ALDH2) enzymes, ethanol and acetaldehyde levels in vivo, and binge-like and preferential drinking behaviors with drinking in the dark and two-bottle choice in animal models with liver injury. Acute and chronic carbon tetrachloride (CCl4), and acute LPS-induced liver injury repressed hepatic ALDH2 activity and expression and consequently, blood and liver acetaldehyde concentrations were increased in these models. In addition, chronic CCl4 and acute LPS treatment inhibited hepatic ADH1 expression and activity, leading to increases in blood and liver ethanol concentrations. Consistent with the increase in acetaldehyde levels, alcohol drinking behaviors were reduced in mice with acute or chronic liver injury. Furthermore, oxidative stress induced by hydrogen peroxide attenuated ADH1 and ALDH2 activity post-transcriptionally, while proinflammatory cytokines led to transcriptional repression of ADH1 and ALDH2 in cultured hepatocytes, which correlated with the repression of transcription factor HNF4α. Collectively, our data suggest that alcohol metabolism is suppressed by inflammation and oxidative stress, which is correlated with decreased drinking behavior.

Polymorphism study of nine SNPs associated with subjective response to alcohol in Chinese Han, Hui, Tibetan, Mongolian and Uygur populations

Heavy alcohol drinking is a major public health problem, causing a large disease, social and economic burden in societies. Subjective response (SR) to alcohol is an intermediate characteristic of heavy drinking. A variety of candidate genes have been reported to be associated with SR to alcohol. In this study, we investigated nine single nucleotide polymorphisms (SNPs) related to SR to alcohol in healthy individuals from five Chinese ethnic groups, the Han, Hui, Tibetan, Mongolian and Uygur populations, and a total of 584 bloodstain samples were collected. The nine SNPs included four SNPs in alcohol-metabolizing genes (ADH1B, ADH1C, ALDH2 and CYP2E1*5B) and five SNPs in genes of neurobiological pathways (GABRA2, OPRM1, CHRNA3, HYKK and SLC6A4). A SNaPshot analysis method was developed to type these SNPs simultaneously, and all samples were typed successfully. Statistical analyses of the allele frequencies indicated that the frequencies of all SNPs, except for ADH1C, showed varying degrees of difference in the five studied ethnic groups. Tibetans showed the highest frequencies of risk alleles for heavy drinking at most loci. The genetic polymorphic differences found in this study revealed the variation in genetic susceptibility to heavy drinking in the studied populations.

ALDH2 gene G487A polymorphism and coronary artery disease: a meta-analysis including 5644 participants

Several studies indicate the mitochondrial Aldehyde Dehydrogenase-2 (ALDH2) gene G487A polymorphism may be correlated with coronary artery disease (CAD) susceptibility, but a clear consensus has yet to be reached. To elucidate the relationship between the ALDH2 gene G487A polymorphism and CAD within the Chinese population, a meta-analysis of 5644 subjects from nine individual studies was performed. Pooled odds ratios (ORs) and their corresponding 95% confidence intervals were assessed using random or fixed-effect models depending the heterogeneity existence or not. Our meta-analysis found a significant association between ALDH2 gene G487A polymorphism and CAD in the Chinese population under allele (OR: 1.830, 95% CI: 1.560-2.140, P = 1.36 × 10^-13 ), recessive (OR: 1.920, 95% CI: 1.530-2.390, P = 1.20 × 10^-8 ), dominant (OR: 1.593, 95% CI: 1.336-1.900, P = 2.22 × 10^-7 ), homozygous (OR: 2.280, 95% CI: 1.810-2.870, P = 3.17 × 10^-12 ) and heterozygous genetic models (OR: 3.330, 95% CI: 2.070-5.370, P = 7.81 × 10^-7 ). The positive correlation between the ALDH2 gene G487A polymorphism and CAD makes the mutation a strong candidate as a genetic risk marker for CAD. Through further analysis, we also found that A allele carriers of ALDH2 gene G487A polymorphism may be particularly susceptible to CAD.

No Interaction with Alcohol Consumption, but Independent Effect of C12orf51 (HECTD4) on Type 2 Diabetes Mellitus in Korean Adults Aged 40-69 Years: The KoGES_Ansan and Ansung Study

Previously, genetic polymorphisms of C12orf51 (HECTD4) (rs2074356 and/or rs11066280) have been shown to be related to alcohol consumption and type 2 diabetes (T2D). This study aimed to prospectively examine whether C12orf51 had an interaction with or independent effect on alcohol consumption and the risk of T2D. The present study included 3,244 men and 3,629 women aged 40 to 69 years who participated in the Korean Genome and Epidemiology Study (KoGES)_Ansan and Ansung Study. Cox proportional hazards models were used to estimate HRs and 95% CIs for T2D. rs2074356 and rs11066280 were associated with the risk of T2D after adjusting for alcohol consumption (rs2074356 for AA: HR = 0.39 and 95% CI = 0.17–0.87 in men, and HR = 0.36 and 95% CI = 0.13–0.96 in women; rs11066280 for AA: HR = 0.44 and 95% CI = 0.23–0.86 in men, and HR = 0.39 and 95% CI = 0.16–0.94 in women). We identified that the association of each variant (rs2074356 and rs11065756) in C12orf51 was nearly unchanged after adjusted for alcohol consumption. Therefore, the association of 2 SNPs in C12orf51 with diabetes may not be mediated by alcohol use. There was no interaction effect between alcohol consumption and the SNPs with T2D. However, even in never-drinkers, minor allele homozygote strongly influenced T2D risk reduction (rs2074356 for AA: HR = 0.35, 95% CI = 0.14–0.90, and p-trend = 0.0035 in men and HR = 0.34, 95% CI = 0.13–0.93, and p-trend = 0.2348 in women; rs11066280 for AA: HR = 0.36, 95% CI = 0.16–0.82, and p-trend = 0.0014 in men and HR = 0.39, 95% CI = 0.16–0.95, and p-trend = 0.3790 in women), while alcohol consumption did not influence the risk of T2D within each genotype. rs2074356 and rs11066280 in or near C12orf51, which is related to alcohol drinking behavior, may longitudinally decrease the risk of T2D, but not through regulation of alcohol consumption.

Alcohol intake and cardiovascular risk factors: A Mendelian randomisation study

Mendelian randomisation studies from Asia suggest detrimental influences of alcohol on cardiovascular risk factors, but such associations are observed mainly in men. The absence of associations of genetic variants (e.g. rs671 in ALDH2) with such risk factors in women – who drank little in these populations – provides evidence that the observations are not due to genetic pleiotropy. Here, we present a Mendelian randomisation study in a South Korean population (3,365 men and 3,787 women) that 1) provides robust evidence that alcohol consumption adversely affects several cardiovascular disease risk factors, including blood pressure, waist to hip ratio, fasting blood glucose and triglyceride levels. Alcohol also increases HDL cholesterol and lowers LDL cholesterol. Our study also 2) replicates sex differences in associations which suggests pleiotropy does not underlie the associations, 3) provides further evidence that association is not due to pleiotropy by showing null effects in male non-drinkers, and 4) illustrates a way to measure population-level association where alcohol intake is stratified by sex. In conclusion, population-level instrumental variable estimation (utilizing interaction of rs671 in ALDH2 and sex as an instrument) strengthens causal inference regarding the largely adverse influence of alcohol intake on cardiovascular health in an Asian population.

Alcoholic liver disease: a synopsis of the Charles Lieber's Memorial Symposia 2009-2012

This paper is based upon the 'Charles Lieber Satellite Symposia' organized by Manuela G. Neuman at each of the 2009-2012 Research Society on Alcoholism (RSA) Annual Meetings. The presentations represent a broad spectrum dealing with alcoholic liver disease (ALD). In addition, a literature search (2008-2013) in the discussed area was performed in order to obtain updated data. The presentations are focused on genetic polymorphisms of ethanol metabolizing enzymes and the role of cytochrome P4502E1 (CYP2E1) in ALD. In addition, alcohol-mediated hepatocarcinogenesis, immune response to alcohol and fibrogenesis in alcoholic hepatitis as well as its co-morbidities with chronic viral hepatitis infections in the presence or absence of human deficiency virus are discussed. Finally, emphasis was led on alcohol and drug interactions as well as liver transplantation for end-stage ALD.

Non invasive fibrosis biomarkers reduce but not substitute the need for liver biopsy

Chronic liver diseases are very common worldwide, particularly those linked to viral hepatitis and to alcoholic and non-alcoholic fatty liver. Their natural history is variable and long-term evolution differs in individual patients. Optimised clinical management of compensated chronic liver diseases requires precise definition of the stage of liver fibrosis, the main determinant of prognosis and of most therapeutic decisions. Liver biopsy is the gold standard for assessment of hepatic fibrosis. However, it is invasive with possible complications, costly and prone to sampling errors. Many non-invasive markers of liver fibrosis have been recently proposed and assessed in the clinical setting as surrogates of liver biopsy. Direct markers are based on biochemical parameters directly linked to fibrogenesis while indirect markers use simple or more sophisticated parameters that correlate with liver fibrosis stages. Non-invasive markers of liver fibrosis have been tested in different forms of chronic liver disease and showed variable diagnostic performance, but accuracy rarely was above 75%-80%. Better results were obtained when markers were combined. On this line, we have recently proposed a set of algorithms that combine sequentially indirect non-invasive markers of liver fibrosis, reaching 90%-95% diagnostic accuracy with significant reduction in the need for liver biopsy. Based on available evidence, it can be anticipated that non-invasive markers of liver fibrosis and their combined use will soon become a most useful tool in the clinical management of many forms of chronic liver disease. However, their implementation is expected to reduce, but not to completely eliminate, the need for liver biopsy.

A human PBPK model for ethanol describing inhibition of gastric motility

A physiologically based pharmacokinetic model for investigating inter-individual and inter-racial variability in ethanol pharmacokinetics is presented. The model is a substantial modification of an existing model which described some genetic polymorphisms in the hepatic alcohol dehydrogenase enzymes. The model was modified to incorporate a description of ethanol absorption from the stomach and gastro-intestinal tract and the retardation of gastric emptying due to a concentration-dependent inhibition of gastric peristalsis. In addition, intra-venous and intra-arterial routes of administration were added to investigate whether the biological structure of the model provided a core which may be easily adapted for any route of exposure. The model is proposed as suitable for the investigation of the effects of both acute and chronic ethanol exposure.