ALDH2 polymorphism and myocardial infarction: From alcohol metabolism to redox regulation

Acute myocardial infarction (AMI) remains a leading cause of death worldwide. Increased formation of reactive oxygen species (ROS) during the early reperfusion phase is thought to trigger lipid peroxidation and disrupt redox homeostasis, leading to myocardial injury. Whilst the mitochondrial enzyme aldehyde dehydrogenase 2 (ALDH2) is chiefly recognised for its central role in ethanol metabolism, substantial experimental evidence suggests an additional cardioprotective role for ALDH2 independent of alcohol intake, which mitigates myocardial injury by detoxifying breakdown products of lipid peroxidation including the reactive aldehydes, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE). Epidemiological evidence suggests that an ALDH2 mutant variant with reduced activity that is highly prevalent in the East Asian population increases AMI risk. Additional studies have uncovered a strong association between coronary heart disease and this ALDH2 mutant variant. It appears this enzyme polymorphism (in particular, in ALDH2*2/2 carriers) has the potential to have wide-ranging effects on thiol reactivity, redox tone and therefore numerous redox-related signaling processes, resilience of the heart to cope with lifestyle-related and environmental stressors, and the ability of the whole body to achieve redox balance. In this review, we summarize the journey of ALDH2 from a mitochondrial reductase linked to alcohol metabolism, via pre-clinical studies aimed at stimulating ALDH2 activity to reduce myocardial injury to clinical evidence for its protective role in the heart.

Aldehyde dehydrogenase 2 rs671 a/A Genotype is Associated with an Increased Risk of Early Onset Coronary Artery Stenosis

Background

The role of aldehyde dehydrogenase 2 (ALDH2) in cardiovascular diseases has been gradually studied. However, it is unclear whether ALDH2 polymorphism is associated with the risk of early onset (onset age ≤55 years old in men and ≤65 years old in women) coronary artery stenosis (CAS). The association between ALDH2 single nucleotide polymorphism (SNP) rs671 and risk in patients with early onset CAS was investigated in this study.

Methods

The study included 213 early onset CAS patients and 352 individuals without CAS were set as controls. The ALDH2 rs671 polymorphism was genotyped by polymerase chain reaction (PCR) - microarray. Differences in ALDH2 rs671 genotypes and alleles between patients and controls were compared. Multiple logistic regression analysis was performed after adjusting for gender, body mass index (BMI), smoking history, drinking history, and diabetes mellitus to assess the relationship between ALDH2 rs671 genotypes and early onset CAS risk.

Results

The frequency of the ALDH2 rs671 G/G genotype was lower in the early onset CAS patients (43.7% vs 55.3%, p=0.007) than that in the controls. The frequency of the ALDH2 rs671 A allele was higher (32.9% vs 25.0%) than that in the controls (p=0.005). After adjusting for other confounding factors, multivariate logistic regression showed that ALDH2 rs671 A/A genotype (A/A vs G/G: odds ratio (OR) 2.508, 95% confidence interval (CI): 1.130-5.569, p=0.024), overweight (BMI≥24.0 vs 18.5-23.9: OR 5.047, 95% CI: 3.275-7.777, p<0.001), history of smoking (yes vs no: OR 2.813, 95% CI: 1.595-4.961, p<0.001), and diabetes mellitus (yes vs no: OR 2.191, 95% CI: 1.397-3.437, p=0.001) were the independent risk factors of early onset CAS.

Conclusion

In men ≤55 years old and women ≤65 years old, individuals with ALDH2 rs671 A/A genotype, overweight (BMI ≥24.0 kg/m2), smoking history, and diabetes mellitus increased risk of developing CAS.

ALDH2 rs671 and MTHFR rs1801133 polymorphisms are risk factors for arteriosclerosis in multiple arteries

BACKGROUND

Arteriosclerosis in multiple arteries has long been associated with heightened cardiovascular risk. Acetaldehyde dehydrogenase 2 (ALDH2) and methylenetetrahydrofolate reductase (MTHFR) play an important role in the pathogenesis of arteriosclerosis by participating in the oxidation and reduction reactions in vascular endothelial cells. The purpose was to investigate the relationship of ALDH2 and MTHFR gene polymorphisms with arteriosclerosis in multiple arteries.

METHODS

410 patients with arteriosclerosis in single artery and 472 patients with arteriosclerosis in multiple arteries were included. The relationship between ALDH2 rs671 and MTHFR rs1801133 polymorphisms and arteriosclerosis in single artery and arteriosclerosis in multiple arteries was analyzed.

RESULTS

The proportion of ALDH2 rs671 A allele (35.6% vs. 30.9%, P = 0.038) and MTHFR rs1801133 T allele (32.6% vs. 27.1%, P = 0.012) in patients with arteriosclerosis in multiple arteries was significantly higher than that in arteriosclerosis in single artery, respectively. The proportion of history of alcohol consumption in patients with ALDH2 rs671 G/G genotype was higher than those in ALDH2 rs671 G/A genotype and A/A genotype (P < 0.001). The results of logistic regression analysis indicated that ALDH2 rs671 A/A genotype (A/A vs. G/G: OR 1.996, 95% CI: 1.258-3.166, P = 0.003) and MTHFR rs1801133 T/T genotype (T/T vs. C/C: OR 1.943, 95% CI: 1.179-3.203, P = 0.009) may be independent risk factors for arteriosclerosis in multiple arteries (adjusted for age, sex, smoking, drinking, hypertension, and diabetes).

CONCLUSIONS

ALDH2 rs671 A/A and MTHFR rs1801133 T/T genotypes may be independent risk factors for arteriosclerosis in multiple arteries.

Effects of the genetic variants of alcohol-metabolizing enzymes on lipid levels in Asian populations: a systematic review and meta-analysis

CONTEXT

Emerging evidence indicates that variants of alcohol-metabolizing enzymes may influence lipid metabolism.

OBJECTIVE

This study aimed to investigate whether the rs671 and rs1229984 variants affect lipid levels in East Asian individuals.

DATA SOURCES

PubMed, Foreign Medical Journal Service, Embase, Cochrane Library, Scopus, MEDLINE, Web of Science, Web of Knowledge, Wanfang, and Chinese Biomedical Literature databases were searched until December 31, 2021.

DATA EXTRACTION

Meta-analyses of studies that examined the effects of alcohol-metabolizing enzyme variants on lipid levels, as well as the interaction with alcohol intake, were selected. Data extraction was conducted independently by two investigators and confirmed by the third.

DATA ANALYSIS

In total, 86 studies (179 640 individuals) were analyzed. The A allele of rs671 (a functional variant in the ALDH2 gene) was linked to higher levels of low-density lipoprotein cholesterol (LDL-C) and lower levels of triglycerides and high-density lipoprotein cholesterol. In contrast, the A allele of the rs1229984 (a functional variant in the ADH2 gene) was associated only with lower levels of LDL-C. The effects of rs671 and rs1229984 on lipid levels were much stronger in Japanese than in Chinese individuals and in males than in females. Regression analysis indicated that the effects of rs671 on lipid levels were independent of alcohol intake in an integrated East Asian population (ie, Japanese, Chinese, and Korean individuals). Intriguingly, alcohol intake had a statistical influence on lipid levels when the sample analyzed was restricted to Japanese individuals or to males.

CONCLUSIONS

The rs671 and rs1229984 variants of alcohol-metabolizing enzymes have significant effects on lipid levels and may serve as genetic markers for lipid dyslipidemia in East Asian populations. Circulating lipid levels in Japanese individuals and in males were modulated by the interaction between rs671 and alcohol intake.

High-Sensitivity C-Reactive Protein to HDL-C Ratio

Inflammation and lipid signaling are involved in the pathogenesis and progression of coronary artery disease (CAD). We proposed that high-sensitivity C-reactive proteins, as a marker of the pro-inflammatory state, and high-density lipoprotein cholesterol (HDL-C), as an anti-atherosclerosis component, should be integrated into a single novel biomarker. Our work was conducted to discuss and compare the predictive ability of the high-sensitivity C-reactive protein to high-density lipoprotein cholesterol ratio (CHR) with other existing indices, for example, neutrophil high-density lipoprotein ratio (NHR) and neutrophil lymphocyte ratio (NLR), in the severity of CAD patients.Based on the results of coronary angiography, patients were divided into the CAD⁺ group, CAD^- group, and control group. The relationship between various serum markers and the severity of coronary artery disease was examined via Spearman's correlation analysis. Logistic regression analysis was conducted to identify the influencing factors of the coronary artery disease severity.This study included 420 patients. The Gensini score was positively correlated with CHR. Multiple regression analysis revealed that the CHR was significantly associated with CAD. CHR is an independent predictor of CAD. The receiver operating characteristic (ROC) analysis provided a cut-off value of 1.17 for CHR to predict CAD, with a specificity of 86.7%, Yoden index of 0.264, and area under the ROC curve of 0.662 (95% confidence intervals 0.606-0.719, P < 0.001). At the same time, the area under the ROC curve of the NHR was 0.652, and that of the NLR was 0.579. The results of the DeLong test indicated that the area under the ROC curve of the CHR was larger than that of the NLR (P = 0.0306). This suggests that the CHR as a predictor of CAD has better diagnostic performance than the NLR.CHR was not only closely related to the presence and severity of CAD but also an independent predictor of severe CAD.

Origin and Spread of the ALDH2 Glu504Lys Allele

Gene polymorphism of acetaldehyde dehydrogenase 2 (ALDH2), a key enzyme for alcohol metabolism in humans, can affect catalytic activity. The ALDH2 Glu504Lys mutant allele has a high-frequency distribution in East Asian populations and has been demonstrated to be associated with an increased risk of cardiovascular disease, stroke, and tumors. Available evidence suggests that the evolution of the ALDH2 gene has been influenced by multiple factors. Random mutations produce Glu504Lys, and genetic drift alters the frequency of this allele; additionally, environmental factors such as hepatitis B virus infection and high-elevation hypoxia affect its frequency through selective effects, ultimately resulting in a high frequency of this allele in East Asian populations. Here, the origin, selection, and spread of the ALDH2 Glu504Lys allele are discussed, and an outlook for further research is proposed to realize a precision medical strategy based on the genetic and environmental variations in ALDH2.

Aldehyde dehydrogenase 2 protects against abdominal aortic aneurysm formation by reducing reactive oxygen species, vascular inflammation, and apoptosis of vascular smooth muscle cells

Mitochondrial aldehyde dehydrogenase 2 (ALDH2) is an enzyme that detoxifies aldehydes by converting them to carboxylic acids. ALDH2 deficiency is known to increase oxidative stress. Increased oxidative stress plays a pivotal role in abdominal aortic aneurysm (AAA) pathogenesis. Reactive oxygen species (ROS) promote degradation of the extracellular matrix (ECM) and vascular smooth muscle cell (VSMC) apoptosis. Reducing oxidative stress by an ALDH2 activator could have therapeutic potential for limiting AAA development. We hypothesized that ALDH2 deficiency could increase the risk for AAA by decreasing ROS elimination and that an ALDH2 activator could provide an alternative option for AAA treatment. The National Center for Biotechnology (NCBI) Gene Expression Omnibus (GEO) database was used. Human aortic smooth muscle cells (HASMCs) were used for the in vitro experiments. Gene-targeted ALDH2*2 KI knock-in mice on a C57BL/6J background and apolipoprotein E knockout (ApoE KO) mice were obtained. An animal model of AAA was constructed using osmotic minipumps to deliver 1000 ng/kg/min angiotensin II (AngII) for 28 days. Patients with AAA had significantly lower ALDH2 expression levels than normal subjects. ALDH2*2 KI mice were susceptible to AngII administration, exhibiting significantly increased AAA incidence rates and increased aortic diameters. Alda-1, an ALDH2 activator, reduced AngII-induced ROS production, NF-kB activation, and apoptosis in HASMCs. Alda-1 attenuated AngII-induced aneurysm formation and decreased aortic expansion in ApoE KO mice. We concluded that ALDH2 deficiency is associated with the development of AAAs in humans and a murine disease model. ALDH2 deficiency increases susceptibility to AngII-induced AAA formation by attenuating anti-ROS effects and increasing VSMC apoptosis and vascular inflammation. Alda-1 was shown to attenuate the progression of experimental AAA in a murine model.

Transcriptome Analysis of Landrace Pig Subcutaneous Preadipocytes during Adipogenic Differentiation

Fat deposition in pigs, which significantly contributes to meat quality, fattening efficiency, reproductive performance, and immunity, is critically affected by preadipocyte adipogenic differentiation. We elucidated adipogenesis in pigs using transcriptome analysis. Preadipocytes from subcutaneous adipose tissue (SAT) of Landrace piglets were differentiated into adipocytes in vitro. RNA sequencing (RNA-seq) used to screen differentially expressed genes (DEGs) during preadipocyte differentiation up to day 8 revealed 15,918 known and 586 novel genes. We detected 21, 144, and 394 DEGs, respectively, including 16 genes differentially expressed at days 2, 4 and 8 compared to day 0. Th number of DEGs increased time-dependently. Lipid metabolism, cell differentiation and proliferation, peroxisome proliferator-activated receptor (PPAR), wingless-type MMTV integration site (Wnt), tumor necrosis factor (TNF) signaling, and steroid biosynthesis were significant at days 2, 4, and 8 compared to day 0 (adjusted p < 0.05). Short time-series expression miner (STEM) analysis obtained 26 clusters of differential gene expression patterns, and nine were significant (p < 0.05). Functional analysis showed many significantly enriched lipid deposition- and cellular process-related biological processes and pathways in profiles 9, 21, 22, and 24. Glycerolipid and fatty-acid metabolism, PPAR signaling, fatty-acid degradation, phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt), and TNF signaling were observed during preadipocyte differentiation in vitro. These findings will facilitate the comprehension of preadipocyte differentiation and fat deposition in pigs.

ALDH2 rs671 polymorphism and the risk of heart failure with preserved ejection fraction (HFpEF) in patients with cardiovascular diseases

Aldehyde dehydrogenase 2 (ALDH2) rs671 polymorphism is an established genetic risk of hypertension, diabetes, and coronary heart diseases in Asian population. Previous experimental data showed ALDH2 regulated inflammation, a potential mechanism of heart failure with preserved ejection fraction (HFpEF). However, clinically, the association between ALDH2 polymorphism and incidence of HFpEF remains unknown. In this prospective cross-sectional study, ALDH2 genotyping was performed in 613 consecutive patients enrolled with cardiovascular diseases (CVDs), including hypertension, coronary heart diseases, and/or diabetes mellitus, with normal left ventricular ejection fraction (LVEF). HFpEF was diagnosed according to symptoms and/or signs of dyspnea, fatigue or ankle swelling, N-terminal pro-B-Type natriuretic peptide (NT pro-BNP ≥ 280 pg/mL), LVEF ≥ 50%, and at least one additional criterion: left atrial enlargement (left atrial diameter > 40 mm), diastolic dysfunction (E/E' ≥ 13 or E'/A' < 1) or concurrently with atrial fibrillation. Finally, of 613 patients with CVD, 379 patients (61.8%) were assigned to the wild-type ALDH2*1/*1 group and 234 patients (38.2%) to the mutation-type ALDH2*2 group according to genotyping results. Sixty-nine patients (11.3%) were diagnosed with HFpEF. In ALDH2*2 group, the occurrence of HFpEF was higher (15.4% vs. 8.7%, p = 0.011) than that in ALDH2*1/*1 group. Leukocyte count, the indicator of systemic inflammation, was significantly higher (6.9 ± 2.4 × 10⁹/L vs. 6.5 ± 1.9 × 10⁹/L, p = 0.010) in ALDH2*2 group compared to ALDH2*1/*1 group. In conclusion, ALDH2*2 variant is associated with the risk of HFpEF in patients with CVD. Increased systemic inflammation probably involved in this disease process.

ALDH2 mediates the dose-response protection of chronic ethanol against endothelial senescence through SIRT1/p53 pathway

Aldehyde dehydrogenase 2 (ALDH2) plays essential roles in drinking-associated diseases or effects. As we have previously reported, ALDH2 mediates acute ethanol-induced eNOS activation in vitro. However, whether chronic ethanol treatment has a dose-response endothelial protection, as well as the possible mediating role of ALDH2 involved, is unclear. Here, we show that appropriate dose of ethanol preserved the expression and activity of ALDH2 and eNOS, and alleviated senescence-associated phenotypes in human aortic endothelial cells. Furthermore, ALDH2 deficiency impairs the dose-response protection of ethanol against endothelial senescence by promoting the accumulation of 4-HNE, the formation of 4-HNE-SIRT1 protein adducts and the subsequent decrease in SIRT1-dependent p53 deacetylation. Collectively, our data indicate that ALDH2 mediates the protection of appropriate ethanol by modulating SIRT1/p53-dependent endothelial senescence.