Inhibiting apoptosis and GSDME-mediated pyroptosis attenuates hepatic injury in septic mice

BACKGROUND

Sepsis is characterized by severe inflammation and organ dysfunction resulting from a dysregulated organismal response to infection. Although pyroptosis has been presumably shown to be a major cause of multiple organ failure and septic death, whether gasdermin E (GSDME)-mediated pyroptosis occurs in septic liver injury and whether inhibiting apoptosis and GSDME-mediated pyroptosis can attenuate septic liver injury remain unclear. This study investigated the role of apoptosis and GSDME-mediated pyroptosis in septic liver injury.

METHODS

Adult male C57BL/6 mice were randomly divided into four groups: sham, cecal ligation puncture (CLP), CLP + Z-DEVD-FMK (a caspase-3 inhibitor, 5 mg/kg), and CLP + Ac-DMLD-CMK (a GSDME inhibitor, 5 mg/kg). Sepsis severity was assessed using the murine sepsis score (MSS). Hepatic tissue damage was observed by the hematoxylin-eosin staining method, the activities of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the levels of malondialdehyde (MDA), the concentrations of interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) were measured according to the related kits, and the changes in the hepatic tissue reactive oxygen species (ROS) levels were detected by immunofluorescence (IF). The protein expression levels of cleaved caspase-3, GSDME-N, IL-1β, B-cell lymphoma-2 (Bcl-2), cytochrome C (Cyt-c), and acetaldehyde dehydrogenase 2 (ALDH2) were detected using western blotting. GSDME expression was detected by immunohistochemistry.

RESULTS

Compared with the Sham group, CLP mice showed high sepsis scores and obvious liver damage. However, in the CLP + Z-DEVD-FMK and CLP + Ac-DMLD-CMK groups, the sepsis scores were reduced and liver injury was alleviated. Compared with the Sham group, the serum ALT and AST activities, MDA and ROS levels, and IL-1β and TNF-α concentrations were increased in the CLP group, as well as the protein expression of cleaved caspase-3, GSDME-N, IL-1β, Cyt-c, and GSDME positive cells (P < 0.05). However, the expression levels of Bcl-2 and ALDH2 protein were decreased (P < 0.05). Compared with the CLP group, the CLP + Z-DEVD-FMK and CLP + Ac-DMLD-CMK groups showed low sepsis scores, ALT and AST activities, MDA and ROS levels, decreased IL-1β and TNF-α concentrations, and decreased expression of cleaved caspase-3, GSDME-N, IL-1β protein expression, and GSDME positive cells (P < 0.05). The expression levels of Bcl-2 and ALDH2 protein were increased (P < 0.05).

CONCLUSION

Apoptosis and GSDME-mediated pyroptosis are involved in the development of sepsis-induced hepatic injury. Inhibition of apoptosis and GSDME-mediated pyroptosis attenuates injury. ALDH2 plays a protective role by inhibiting apoptosis and pyroptosis.

Analysis of Correlation Between Coronary Heart Disease and Genetic Polymorphism Detected by Gold Magnetic Nanoparticles Chromatography

It aimed to explore the correlation of Glu504Lys locus mutation of aldehyde dehydrogenase-2 (ALDH2) with coronary heart disease (CHD) based on gold magnetic nanoparticles (GMNPs) chromatography and amplification refractory mutation system-PCR (ARMS-PCR). 120 CHD patients admitted to the cardiovascular Department of Wenling First People's Hospital affiliated to Wenzhou Medical University from December 2020 to December 2021 were selected as Case group and 80 non-CHD patients admitted during the same period were selected as Ctrl group. The venous blood and indexes of Total Cholesterol (TC), Triglyceride (TG), Low Density Lipoprotein Cholesterol (LDL-C), High Density Lipoprotein Cholesterol (HDL-C), and Fasting Blood Glucose (FBS) were collected. The ARMS-PCR GMNPs chromatography based on ARMS-PCR and immunochromatography assay was adopted to detect gene polymorphism of ALDH2. Correlation between ALDH2 gene polymorphism and risk factors of CHD was analyzed via logistic regression. In contrast to Ctrl group, the genotypes of GG, GA, and AA in Case group were evidently different (P < 0.05), and the frequency of A allelic gene was obviously increased (P < 0.05). Under the dominant model, frequency of GA + AA genotype in Case group was remarkably higher in contrast to Ctrl group (P < 0.05). Under the recessive model, there was no obvious difference in genotype frequency between two groups. In contrast to Ctrl group, TC, LDL-C, and FBS in Case group were notably increased (P < 0.05), while HDL-C was notably decreased (P < 0.05). The distribution frequency of abnormal LDL-C, HDL-C, and FBS in Case group was notably higher in contrast to Ctrl group (P < 0.05). LDL-C and FBS had no obvious effect on the genotypes and frequency distribution of alleles in CHD patients. However, the frequency distribution of genotypes of GA and AA and A allelic gene in patients with abnormal HDL-C was notably lower in contrast to those with normal HDL-C (P < 0.05). Logistic regression analysis showed that abnormal HDC-C with A allelic gene were independent risk factors for CHD (P = 0.001, OR = 1.934). The gene polymorphism of Glu504Lys locus of ALDH2 was closely related to the pathogenesis of CHD, A allelic gene may be a susceptibility gene for CHD, and patients with abnormal HDC-C and carried A allelic gene had relatively higher incidence of CHD.

Exploring patterns of alcohol use and alcohol use disorder among Asian Americans with a finer lens

BACKGROUND

National survey data suggest Asian Americans (AA) are less likely to consume alcohol and develop AUD than Americans in other groups. However, it is common for AA to be born outside of the US and carry gene variants that alter alcohol metabolism, both of which can lead to lower levels of alcohol involvement. The current study examined differences in alcohol use and AUD between AA and other groups before and after controlling for birth location and gene variants.

DESIGN

Past year alcohol measures were examined from adults 18+ (N=22,848) in the 2012-2013 National Epidemiologic Survey on Alcohol and Related Conditions III before and after controlling for birth location (inside or outside of the US) and gene variants (ALDH2*2 and ADH1B*2/ADH1B*3). Gender gaps in alcohol measures also were assessed.

RESULTS

Before adjustments, AA were less likely than White Americans to drink in the previous year (OR=0.50, 95% CI 0.41-0.62), binge (OR=0.68, 95% CI 0.52-0.88), engage in frequent heavy drinking (OR=0.55, 95% CI 0.42-0.73), and reach criteria for AUD (OR=0.71, 95% CI 0.53-0.94). After controlling for birth location and gene variants, AA remained less likely to drink in the past year (OR=0.54, 95% CI 0.41-0.70) but all other differences disappeared. Gender gaps were only observed for AA born outside of the US, highlighting the importance of experience rather than racial category per se.

CONCLUSIONS

Findings indicate that heterogeneity among AA leads to spurious generalizations regarding alcohol use and AUD and challenge the model minority myth.

Aldehyde Dehydrogenase 2 (ALDH2): A novel sorafenib target in hepatocellular carcinoma unraveled by the proteome-wide cellular thermal shift assay

Sorafenib is a multikinase inhibitor indicated for first-line treatment of unresectable hepatocellular carcinoma. Despite its widespread use in the clinic, the existing knowledge of sorafenib mode-of-action remains incomplete. To build upon the current understanding, we used the Cellular Thermal Shift Assay (CETSA) coupled to Mass Spectrometry (CETSA-MS) to monitor compound binding to its target proteins in the cellular context on a proteome-wide scale. Among the potential sorafenib targets, we identified aldehyde dehydrogenase 2 (ALDH2), an enzyme that plays a major role in alcohol metabolism. We validated the interaction of sorafenib with ALDH2 by orthogonal methods using pure recombinant protein, proving that this interaction is not mediated by other cellular components. Moreover, we showed that sorafenib inhibits ALDH2 activity, supporting a functional role for this interaction. Finally, we were able to demonstrate that both ALDH2 protein expression and activity were reduced in sorafenib-resistant cells compared to the parental cell line. Overall, our study allowed the identification of ALDH2 as a novel sorafenib target and sheds light on its potential role in both hepatocellular carcinoma and sorafenib resistance condition.

The ALDH2 gene rs671 polymorphism is associated with cardiometabolic risk factors in East Asian population: an updated meta-analysis

Introduction

Acetaldehyde dehydrogenase 2 (ALDH2) had reported as a prominent role in the development of cardiometabolic diseases among Asians. Our study aims to investigate the relationship between ALDH2 polymorphism and cardiometabolic risk factors in East Asian population.

Method

We searched databases of PubMed, Web of Science, and Embase updated to Oct 30th, 2023. We extracted data of BMI, Hypertension, SBP, DBP, T2DM, FBG, PPG, HbA1c, TG, TC, LDL-C and HDL-C.

Result

In total, 46 studies were finally included in our meta-analysis, containing, 54068 GG and, 36820 GA/AA participants. All outcomes related to blood pressure revealed significant results (hypertension OR=0.83 [0.80, 0.86]; SBP MD=-1.48 [-1.82, -1.14]; DBP MD=-1.09 [-1.58, -0.61]). FBG showed a significant difference (MD=-0.10 [-0.13, -0.07]), and the lipid resulted significantly in some outcomes (TG MD=-0.07 [-0.09, -0.04]; LDL-C MD=-0.04 [-0.05, -0.02]). As for subgroups analysis, we found that in populations without severe cardiac-cerebral vascular diseases (CCVDs), GG demonstrated a significantly higher incidence of T2DM (T2DM OR=0.88 [0.79, 0.97]), while the trend was totally opposite in population with severe CCVDs (T2DM OR=1.29 [1.00, 1.66]) with significant subgroup differences.

Conclusion

Our updated meta-analysis demonstrated that ALDH2 rs671 GG populations had significantly higher levels of BMI, blood pressure, FBG, TG, LDL-C and higher risk of hypertension than GA/AA populations. Besides, to the best of our knowledge, we first report GG had a higher risk of T2DM in population without severe CCVDs, and GA/AA had a higher risk of T2DM in population with severe CCVDs.Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO, identifier CRD42023389242.

Neutrophil ALDH2 is a new therapeutic target for the effective treatment of sepsis-induced ARDS

Acetaldehyde dehydrogenase 2 (ALDH2) mutations are commonly found in a subgroup of the Asian population. However, the role of ALDH2 in septic acute respiratory distress syndrome (ARDS) remains unknown. Here, we showed that human subjects carrying the ALDH2rs671 mutation were highly susceptible to developing septic ARDS. Intriguingly, ALDH2rs671-ARDS patients showed higher levels of blood cell-free DNA (cfDNA) and myeloperoxidase (MPO)-DNA than ALDH2WT-ARDS patients. To investigate the mechanisms underlying ALDH2 deficiency in the development of septic ARDS, we utilized Aldh2 gene knockout mice and Aldh2rs671 gene knock-in mice. In clinically relevant mouse sepsis models, Aldh2-/- mice and Aldh2rs671 mice exhibited pulmonary and circulating NETosis, a specific process that releases neutrophil extracellular traps (NETs) from neutrophils. Furthermore, we discovered that NETosis strongly promoted endothelial destruction, accelerated vascular leakage, and exacerbated septic ARDS. At the molecular level, ALDH2 increased K48-linked polyubiquitination and degradation of peptidylarginine deiminase 4 (PAD4) to inhibit NETosis, which was achieved by promoting PAD4 binding to the E3 ubiquitin ligase CHIP. Pharmacological administration of the ALDH2-specific activator Alda-1 substantially alleviated septic ARDS by inhibiting NETosis. Together, our data reveal a novel ALDH2-based protective mechanism against septic ARDS, and the activation of ALDH2 may be an effective treatment strategy for sepsis.

ALDH2 is a novel biomarker and exerts an inhibitory effect on melanoma

Melanoma is a malignant skin tumor. This study aimed to explore and assess the effect of novel biomarkers on the progression of melanoma. Differently expressed genes (DEGs) were screened from GSE3189 and GSE46517 datasets of Gene Expression Omnibus database using GEO2R. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were conducted based on the identified DEGs. Hub genes were identified and assessed using protein-protein interaction networks, principal component analysis, and receiver operating characteristic curves. Quantitative real-time polymerase chain reaction was employed to measure the mRNA expression levels. TIMER revealed the association between aldehyde dehydrogenase 2 (ALDH2) and tumor immune microenvironment. The viability, proliferation, migration, and invasion were detected by cell counting kit-8, 5-ethynyl-2'-deoxyuridine, wound healing, and transwell assays. Total 241 common DEGs were screened out from GSE3189 and GSE46517 datasets. We determined 6 hub genes with high prediction values for melanoma, which could distinguish tumor samples from normal samples. ALDH2, ADH1B, ALDH3A2, DPT, EPHX2, and GATM were down-regulated in A375 and SK-MEL-2 cells, compared with the human normal melanin cell line (PIG1 cells). ALDH2 was selected as the candidate gene in this research, presenting a high diagnostic and predictive value for melanoma. ALDH2 had a positive correlation with the infiltrating levels of immune cells in melanoma microenvironment. Overexpression of ALDH2 inhibited cell viability, proliferation, migration, and invasion of A375/SK-MEL-2 cells. ALDH2 is a new gene biomarker of melanoma, which exerts an inhibitory effect on melanoma.

Association of liver fibrosis with extrahepatic cancer in steatotic liver disease patients with PNPLA3 I148M GG genotype

The impacts of patatin-like phospholipase domain-containing protein 3 (PNPLA3) I148M-rs738409, methylenetetrahydrofolate reductase (MTHFR) Ala222Val-rs1801133, and aldehyde dehydrogenase 2 (ALDH2) Glu504Lys-rs671 on the outcomes of Taiwanese patients with steatotic liver disease (SLD) have remained elusive. An 8-year prospective cohort study of patients with (n = 546) and without (n = 580) SLD (controls) was undertaken in a Taiwanese tertiary care center. The 546 SLD patients comprised 306 (56.0%) men and 240 (44.0%) women with mean ages of 53.3 and 56.4 years, respectively. Compared with the controls, SLD patients had an increased frequency of the PNPLA3 I148M-rs738409 GG genotype (25.5 vs. 5.9%, p = 0.001). Among the SLD patients, 236 (43.1%) suffered cardiovascular events, 52 (9.5%) showed extrahepatic cancers, 13 (2.38%) experienced hepatic events, including hepatocellular carcinoma (n = 3, 0.5%) and liver cirrhosis (n = 8, 1.47%), and none died. The Fibrosis-4 (FIB-4) scores were associated with extrahepatic cancer (hazard ratio [HR] 1.325; 95% confidence interval [CI], 1.038-1.691) and cirrhosis development (HR 1.532; 95% CI, 1.055-2.224), and the PNPLA3 I148M-rs738409 G allele (β = 0.158, 95% CI, 0.054-0.325) was associated with the FIB-4 score. Stratified analyses showed that the impact of the FIB-4 score on extrahepatic cancer development was evident only in SLD patients with the PNPLA3 I148M-rs738409 GG genotype (HR 1.543; 95% CI, 1.195-1.993) and not in patients with the GC or CC genotype. Moreover, the ALDH2 Glu504Lys-rs671 G allele had a dose-dependent effect on alcoholism, and the MTHFR and ALDH2 genotypes were not significantly associated with SLD patient outcomes. In conclusion, special vigilance should be exercised for emerging extrahepatic cancer in SLD patients with the PNPLA3 I148M-rs738409 GG genotype and high FIB-4 scores.

Contributing roles of mitochondrial dysfunction and hepatocyte apoptosis in liver diseases through oxidative stress, post-translational modifications, inflammation, and intestinal barrier dysfunction

This review provides an update on recent findings from basic, translational, and clinical studies on the molecular mechanisms of mitochondrial dysfunction and apoptosis of hepatocytes in multiple liver diseases, including but not limited to alcohol-associated liver disease (ALD), metabolic dysfunction-associated steatotic liver disease (MASLD), and drug-induced liver injury (DILI). While the ethanol-inducible cytochrome P450-2E1 (CYP2E1) is mainly responsible for oxidizing binge alcohol via the microsomal ethanol oxidizing system, it is also responsible for metabolizing many xenobiotics, including pollutants, chemicals, drugs, and specific diets abundant in n-6 fatty acids, into toxic metabolites in many organs, including the liver, causing pathological insults through organelles such as mitochondria and endoplasmic reticula. Oxidative imbalances (oxidative stress) in mitochondria promote the covalent modifications of lipids, proteins, and nucleic acids through enzymatic and non-enzymatic mechanisms. Excessive changes stimulate various post-translational modifications (PTMs) of mitochondrial proteins, transcription factors, and histones. Increased PTMs of mitochondrial proteins inactivate many enzymes involved in the reduction of oxidative species, fatty acid metabolism, and mitophagy pathways, leading to mitochondrial dysfunction, energy depletion, and apoptosis. Unique from other organelles, mitochondria control many signaling cascades involved in bioenergetics (fat metabolism), inflammation, and apoptosis/necrosis of hepatocytes. When mitochondrial homeostasis is shifted, these pathways become altered or shut down, likely contributing to the death of hepatocytes with activation of inflammation and hepatic stellate cells, causing liver fibrosis and cirrhosis. This review will encapsulate how mitochondrial dysfunction contributes to hepatocyte apoptosis in several types of liver diseases in order to provide recommendations for targeted therapeutics.

Aldehyde dehydrogenase 2 deficiency reinforces formaldehyde-potentiated pro-inflammatory responses and glycolysis in macrophages

Aldehyde dehydrogenase 2 (ALDH2) deficiency caused by   genetic variant is present in more than 560 million people of East Asian descent, which can be identified by apparent facial flushing from acetaldehyde accumulation after consuming alcohol. Recent findings indicated that ALDH2 also played a critical role in detoxification of formaldehyde (FA). Our previous studies showed that FA could enhance macrophagic inflammatory responses through the induction of HIF-1α-dependent glycolysis. In the present study, pro-inflammatory responses and glycolysis promoted by 0.5 mg/m3 FA were found in mice with Aldh2 gene knockout, which was confirmed in the primary macrophages isolated from Aldh2 gene knockout mice treated with 50 μM FA. FA at 50 and 100 μM also induced stronger dose-dependent increases of pro-inflammatory responses and glycolysis in RAW264.7 murine macrophages with knock-down of ALDH2, and the enhanced effects induced by 50 μM FA was alleviated by inhibition of HIF-1α in RAW264.7 macrophages with ALDH2 knock-down. Collectively, these results clearly demonstrated that ALDH2 deficiency reinforced pro-inflammatory responses and glycolysis in macrophages potentiated by environmentally relevant concentration of FA, which may increase the susceptibility to inflammation and immunotoxicity induced by environmental FA exposure.

An idea to explore: Determination of single nucleotide polymorphisms in alcohol metabolism-related genes using PCR-based assays to understand the link between an individual's genotype and phenotype

Here, we propose a laboratory exercise to quickly determine single nucleotide polymorphisms (SNPs) in human alcohol dehydrogenase 1B (ADH1B) and aldehyde dehydrogenase 2 (ALDH2) genes involved in alcohol metabolism. In this exercise, two different genotyping methods based on polymerase chain reaction (PCR), namely allele-specific (AS) PCR and a PCR-restriction fragment polymorphism (RFLP) analysis, can be performed under the same PCR program (2-step × 35 cycles, 35 min total) in parallel using a hair root lysate as a template. In AS-PCR, the target regions of the G- or A-alleles of both genes are allele-specifically amplified in a single PCR tube. In the PCR-RFLP analysis, the two genes are amplified simultaneously in a single tube, and then a portion of the PCR product is double-digested with restriction enzymes MslI and Eam1104I for 5 min. The resulting reaction products of each method are electrophoresed side by side, and the genotypes are determined from the DNA band patterns. With the optimized protocol, the whole process from template preparation to genotyping can be completed in about 75 min. During PCR, students also perform an ethanol patch test to estimate their ability to metabolize alcohol. This series of experiments can help students learn the principles and applications of PCR/SNP analyses. By comparing the genotypes revealed by PCR and the phenotypes revealed by the patch tests, students can gain a better understanding of the clinical value of genetic testing.

Asian flush is a potential protective factor against COVID-19: a web-based retrospective survey in Japan

BACKGROUND

Coronavirus disease 2019 (COVID-19), first reported in December 2019, spread worldwide in a short period, resulting in numerous cases and associated deaths; however, the toll was relatively low in East Asia. A genetic polymorphism unique to East Asians, Aldehyde dehydrogenase 2 rs671, has been reported to confer protection against infections.

METHOD

We retrospectively investigated the association between the surrogate marker of the rs671 variant, the skin flushing phenomenon after alcohol consumption, and the timing of COVID-19 incidence using a web-based survey tool to test any protective effects of rs671 against COVID-19.

RESULTS

A total of 807 valid responses were received from 362 non-flushers and 445 flushers. During the 42 months, from 12/1/2019 to 5/31/2023, 40.6% of non-flushers and 35.7% of flushers experienced COVID-19. Flushers tended to have a later onset (Spearman's partial rank correlation test, p = 0.057, adjusted for sex and age). Similarly, 2.5% of non-flushers and 0.5% of flushers were hospitalized because of COVID-19. Survival analysis estimated lower risks of COVID-19 and associated hospitalization among flushers (p = 0.03 and <0.01, respectively; generalized Wilcoxon test). With the Cox proportional hazards model covering 21 months till 8/31/2021, when approximately half of the Japanese population had received two doses of COVID-19 vaccine, the hazard ratio (95% confidence interval) of COVID-19 incidence was estimated to be 0.21 (0.10-0.46) for flusher versus non-flusher, with adjustment for sex, age, steroid use, and area of residence.

CONCLUSIONS

Our study suggests an association between the flushing phenomenon after drinking and a decreased risk of COVID-19 morbidity and hospitalization, suggesting that the rs671 variant is a protective factor. This study provides valuable information for infection control and helps understand the unique constitutional diversity of East Asians.

The Binding of HSPA8 and Mitochondrial ALDH2 Mediates Oxygen-Glucose Deprivation-Induced Fibroblast Senescence

Cellular senescence refers to the permanent and irreversible cessation of the cell cycle. Recently, it has gained significant interest as a promising target for preventing cardiovascular diseases. Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that has been closely linked with an increased risk of cardiovascular diseases. In this study, bioinformatics analysis revealed that the signaling pathway for fibroblast senescence is significantly activated in mice after myocardial infarction (MI), and that ALDH2 might be a crucial molecule responsible for inducing this change. Therefore, we created an NIH3T3 fibroblast cell line oxygen-glucose deprivation (OGD) model to replicate the conditions of MI in vitro. We further revealed that decreased ALDH2 enzyme activity is a critical factor that affects fibroblast senescence after OGD, and the activation of ALDH2 can improve the mitochondrial damage caused by OGD. We identified Heat Shock 70-kDa Protein 8 (HSPA8) as an interacting protein of ALDH2 through co-immunoprecipitation (Co-IP) and mass spectrometry (MS) detection. Subsequently, our studies showed that HSPA8 translocates to the mitochondria after OGD, potentially binding to ALDH2 and inhibiting its enzyme activity. By transfecting siRNA to inhibit HSPA8 expression in cells, it was found that ALDH2 enzyme activity can be significantly increased, and the senescence characteristics induced by OGD in NIH3T3 cells can be improved. In conclusion, the data from this study suggest that HSPA8, in conjunction with ALDH2, could regulate fibroblast senescence after oxygen-glucose deprivation, providing a new direction and foundation for effectively intervening in fibroblast senescence after myocardial infarction.

ALDH2 mitigates LPS-induced cardiac dysfunction, inflammation, and apoptosis through the cGAS/STING pathway

BACKGROUND

Sepsis is a severe syndrome of organ dysfunction that often leads to cardiac dysfunction and endangers life. The role of mitochondrial aldehyde dehydrogenase 2 (ALDH2) in LPS-induced myocardial injury is unclear. The purpose of this study was to assess the role of ALDH2 in lipopolysaccharide (LPS)-induced myocardial injury and the regulatory mechanism and to identify potential therapeutic strategies for treating this condition.

METHODS

An in vivo model was established by 12 h of LPS (10 mg/kg, intraperitoneal injection) stimulation, and an in vitro model was generated by stimulating H9C2 cells with LPS (10 μg/ml) for 12 h. We then used the ALDH2 activator Alda-1 and the ALDH2 inhibitor daidzin to assess their effects on LPS-induced cardiac injury. Cardiac function in mice was evaluated by using cardiac ultrasound. We used various methods to evaluate inflammation, apoptosis, and oxidative stress, including ELISA, flow cytometry, JC-1 staining, Western blotting, and DCFH-DA staining. Additionally, we used a small interfering RNA (siRNA) to knock down cyclic GMP-AMP synthase (cGAS) to further investigate the relationship between ALDH2 and cGAS in LPS-induced cardiac injury.

RESULTS

LPS-induced cardiac dysfunction and increased the levels of the cardiac injury markers creatine kinase-MB (CKMB) and lactate dehydrogenase (LDH) in vivo. This change was accompanied by an increase in reactive oxygen species (ROS) levels, which exacerbated the oxidative stress response and regulated apoptosis through cleaved caspase-3, BAX, BCL-2. The expression of inflammatory cytokines such as IL-6/IL-1β/TNF-α was also upregulated. However, these effects were reversed by pretreatment with Alda-1 via the inhibition of cGAS/stimulator of interferon genes (STING) signaling pathway. Interestingly, LPS, Alda-1 and daidzin altered the activity of ALDH2 but did not regulate its protein expression. Knocking down cGAS in H9C2 cardiomyocytes alleviated LPS-induced cardiac inflammation, apoptosis, and ROS production and weakened the synergistic effect of daidzin.

CONCLUSION

We demonstrated that ALDH2 alleviated LPS-induced cardiac dysfunction, inflammation, and apoptosis through the cGAS/STING signaling pathway, thereby protecting against LPS-induced cardiac injury. This study identifies a novel therapeutic approach for treating sepsis-induced cardiomyopathy (SIC).

Deficiency of aldehyde dehydrogenase 2 aggravates ethanol-induced cytotoxicity in N2a cells via CaMKII/Drp1-mediated mitophagy

Chronic alcohol abuse causes brain damage and has been associated with an increased risk of Alzheimer's disease. The toxic metabolite of alcohol, acetaldehyde, which is converted to acetate by aldehyde dehydrogenase 2 (ALDH2), has been shown to induce excessive mitochondrial fragmentation and dysfunction leading to neurotoxicity. However, it is still unclear how alcohol affects mitochondrial function in ALDH2-deficient cells. The present study investigated the association between abnormal mitochondrial dynamics, mitophagy and cytotoxicity in ALDH2-deficient N2a cells treated with ethanol. It was found that ethanol induced dynamin-related protein 1 (Drp1)-mediated mitochondrial fragmentation and impaired mitochondrial function, causing excessive mitophagy and cytotoxicity in ALDH2-deficient N2a cells while inducing Ca2+ influx and activating Ca2+/calmodulin-dependent protein kinase II (CaMKII). Inhibition of Ca2+ overload or CaMKII activation prevented Drp1 phosphorylation and ameliorated ethanol-induced mitophagy and cytotoxicity, indicating that Ca2+-dependent CaMKII activation was critical for mediating Drp1-dependent excessive mitochondrial fission and mitophagy in ALDH2-deficient N2a cells. The results of the present study suggested that prevention of intracellular Ca2+ overload might be beneficial for preventing neurotoxicity associated with alcohol abuse in individuals with defective ALDH2.

ALDH2 activation attenuates oxygen-glucose deprivation/reoxygenation-induced cell apoptosis, pyroptosis, ferroptosis and autophagy

PURPOSE

It is previously reported that aldehyde dehydrogenase 2 family member (ALDH2) shows neuroprotective effects in cerebral ischemia/reperfusion injury. However, whether the protective effects are through mediating the programmed cell death is yet to be fully elucidated.

METHODS

In vitro oxygen-glucose deprivation/reoxygenation (OGD/R) model was established in HT22 cells and mouse cortical neurons. Subsequently, ALDH2 expression were assessed by qRT-PCR and western blot. The methylation status was examined by methylation-specific PCR (MS-PCR). Then, ALDH2 expression was promoted and suppressed to explore the role of ALDH2 in OGD/R-treated cells. CCK-8 assay was applied to detect cell viability, and flow cytometry was applied to evaluate cell apoptosis. Western blot was applied to detect the apoptosis-related proteins (Caspase 3, Bcl-2 and Bax), necroptosis-related proteins (RIP3 and MLKL), pyroptosis-related proteins (NLRP3 and GSDMD), ferroptosis-related protein (ACSL4 and GPX4), and autophagy-related proteins (LC3B, and p62). IL-1β and IL-18 production was evaluated by ELISA assay. Reactive oxygen species production and Fe2+ content were evaluated by the corresponding detection kit.

RESULTS

In OGD/R-treated cells, ALDH2 expression was decreased, which was due to the hypermethylation of ALDH2 in the promoter region. ALDH2 overexpression improved cell viability and ALDH2 knockdown suppressed cell viability in OGD/R-treated cells. We also found that ALDH2 overexpression attenuated OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy, while ALDH2 knockdown facilitated the OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy.

CONCLUSIONS

Collectively, our results implied that ALDH2 attenuated OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy to promote cell viability in HT22 cells and mouse cortical neurons.

Genetic influences on alcohol flushing in East Asian populations

BACKGROUND

Although it is known that variation in the aldehyde dehydrogenase 2 (ALDH2) gene family influences the East Asian alcohol flushing response, knowledge about other genetic variants that affect flushing symptoms is limited.

METHODS

We performed a genome-wide association study meta-analysis and heritability analysis of alcohol flushing in 15,105 males of East Asian ancestry (Koreans and Chinese) to identify genetic associations with alcohol flushing. We also evaluated whether self-reported flushing can be used as an instrumental variable for alcohol intake.

RESULTS

We identified variants in the region of ALDH2 strongly associated with alcohol flushing, replicating previous studies conducted in East Asian populations. Additionally, we identified variants in the alcohol dehydrogenase 1B (ADH1B) gene region associated with alcohol flushing. Several novel variants were identified after adjustment for the lead variants (ALDH2-rs671 and ADH1B-rs1229984), which need to be confirmed in larger studies. The estimated SNP-heritability on the liability scale was 13% (S.E. = 4%) for flushing, but the heritability estimate decreased to 6% (S.E. = 4%) when the effects of the lead variants were controlled for. Genetic instrumentation of higher alcohol intake using these variants recapitulated known associations of alcohol intake with hypertension. Using self-reported alcohol flushing as an instrument gave a similar association pattern of higher alcohol intake and cardiovascular disease-related traits (e.g. stroke).

CONCLUSION

This study confirms that ALDH2-rs671 and ADH1B-rs1229984 are associated with alcohol flushing in East Asian populations. Our findings also suggest that self-reported alcohol flushing can be used as an instrumental variable in future studies of alcohol consumption.

Relationship between esophageal squamous cell carcinoma risk and alcohol-related ALDH2 and ADH1B polymorphisms: Evidence from a meta-analysis and Mendelian randomization analysis

BACKGROUND

Previous studies have shown that ALDH2 and ADH1B genes may be associated with alcohol metabolism and the risk of esophageal squamous cell carcinoma (ESCC), with inconsistent results. This meta-analysis aimed at comprehensively assessing the associations between ALDH2 and ADH1B polymorphisms and the risk of ESCC to synthesize and clarify the evidence.

METHODS

We calculated summary estimates of the associations between four genetic variants (rs671 and rs674 in ALDH2, and rs1229984 and rs1042026 in ADH1B) and the ESCC risk across 23 publications in the additive model and allelic model. Venice criteria, Bayesian false discovery probability (BFDP), and false-positive reporting probability (FPRP) were used to assess the strength of epidemiological evidence. Heterogeneity among studies was evaluated by using the Higgin's I2 statistic, and publication bias was assessed by using funnel plots and Begg's test. A Mendelian randomization (MR) analysis was performed to determine the causal association between alcohol intake and esophageal cancer risk. Data from the HaploReg v4.1 and PolyPhen-2 were analyzed for functional annotations.

RESULTS

Of the four genetic variants, rs671 of ALDH2 was associated with a significantly reduced risk of ESCC (OR: 0.60, 95% CI: 0.50-0.73), whereas rs1229984 of ADH1B was associated with a significantly increased risk (2.50, 95% CI: 1.70-3.69) in the additive model. In the allelic model, the variant rs1229984 of ADH1B also increased the risk of ESCC (OR: 1.50; 95% CI: 1.21-1.87). The result for the variant rs671 was considered as strong epidemiological evidence. Functional annotations identified that the four variants were related to the enhancer histone marks and motif changes. The other two variants were not associated with the ESCC risk (rs674 of ALDH2 OR: 1.22, 95% CI: 0.71-2.12; rs1042026 of ADH1B OR: 1.28, 95% CI: 0.52-3.14) in the additive model. The MR analysis did not find a causal effect of alcohol on the esophageal cancer risk.

CONCLUSIONS

The results showed that ADH1B rs1229984 was significantly associated with an increased the risk of ESCC.

Host ALDH2 deficiency aggravates nonalcoholic steatohepatitis through gut-liver axis

Nonalcoholic steatohepatitis (NASH) is the major cause of liver dysfunction. Animal and population studies have shown that mitochondrial aldehyde dehydrogenase (ALDH2) is implicated in fatty liver disease. However, the role of ALDH2 in NASH and the underlying mechanisms remains unclear. To address this issue, ALDH2 knockout (ALDH2-/-) mice and wild-type littermate mice were fed a methionine-and choline-deficient (MCD) diet to induce a NASH model. Fecal, serum, and liver samples were collected and analyzed to investigate the impact of the gut microbiota and bile acids on this process. We found that MCD-fed ALDH2-/- mice exhibited increased serum pro-inflammation cytokines, hepatic inflammation and fat accumulation than their wild-type littermates. MCD-fed ALDH2-/- mice exhibited worsened MCD-induced intestinal inflammation and barrier damage, and gut microbiota disorder. Furthermore, mice receiving microbiota from MCD-fed ALDH2-/- mice had increased severity of NASH compared to those receiving microbiota from MCD-fed wild-type mice. Notably, the intestinal Lactobacillus was significantly reduced in MCD-fed ALDH2-/- mice, and gavage with Lactobacillus cocktail significantly improved MCD-induced NASH. Finally, we found that ALDH2-/- mice had reduced levels of bile salt hydrolase and specific bile acids, especially lithocholic acid (LCA), accompanied by downregulated expression of the intestinal FXR-FGF15 pathway. Supplementation of LCA in ALDH2-/- mice upregulated intestinal FXR-FGF15 pathway and alleviated NASH. In summary, ALDH2 plays a critical role in the development of NASH through modulation of gut microbiota and bile acid. The findings suggest that supplementing with Lactobacillus or LCA could be a promising therapeutic approach for treating NASH exacerbated by ALDH2 deficiency.

Fanconi anemia and Aldehyde Degradation Deficiency Syndrome: Metabolism and DNA repair protect the genome and hematopoiesis from endogenous DNA damage

We have identified a set of Japanese children with hypoplastic anemia caused by combined defects in aldehyde degrading enzymes ADH5 and ALDH2. Their clinical characteristics overlap with a hereditary DNA repair disorder, Fanconi anemia. Our discovery of this disorder, termed Aldehyde Degradation Deficiency Syndrome (ADDS), reinforces the notion that endogenously generated aldehydes exert genotoxic effects; thus, the coupled actions of metabolism and DNA repair are required to maintain proper hematopoiesis and health.

Effects of the major formaldehyde catalyzer ADH5 on phenotypes of fanconi anemia zebrafish model

BACKGROUND

Fanconi anemia (FA) is a devastating hereditary disorder for which we desperately need a novel therapeutic strategy. It is caused by mutations in one of at least 22 genes in the FA pathway and is characterized by developmental abnormalities, bone marrow failure, and cancer predisposition. The FA pathway is required for the efficient repair of damaged DNA, including interstrand cross-links (ICL). Recent studies indicate formaldehyde as an ultimate endogenous cause of DNA damage in FA pathophysiology. Formaldehyde can form DNA adducts as well as ICLs by inducing covalent linkages between opposite strands of double-stranded DNA.

METHODS AND RESULTS

In this study, we generated a disease model of FA in zebrafish by disrupting the ube2t or fancd2 gene, which resulted in a striking phenotype of female-to-male sex reversal. Since formaldehyde is detoxified from the body by alcohol dehydrogenase 5 (ADH5), we generated fancd2-/-/adh5-/- zebrafish. We observed a body size reduction and a lower number of mature spermatozoa than wild-type or single knockout zebrafish. To evaluate if increased activity in ADH5 can affect the FA phenotype, we overexpressed human ADH5 in fancd2-/- zebrafish. The progress of spermatogenesis seemed to be partially recovered due to ADH5 overexpression.

CONCLUSIONS

Our results suggest potential utility of an ADH5 enzyme activator as a therapeutic measure for the clearance of formaldehyde and treatment of FA.

Mitochondrial aldehyde dehydrogenase rescues against diabetic cardiomyopathy through GSK3β-mediated preservation of Mitochondrial integrity and parkin-mediated mitophagy

Mitochondrial aldehyde dehydrogenase (ALDH2) offers proven cardiovascular benefit although its impact in diabetes remains elusive. This study examined the effect of ALDH2 overexpression (OE) and knockout (KO) on diabetic cardiomyopathy and mechanism involved with a focus on mitochondrial integrity. ALDH2 OE and KO mice were challenged with streptozotocin (STZ, 200 mg/kg. i.p.) to establish diabetes. Diabetic patients displayed reduced plasma ALDH2 activity, cardiac remodeling and diastolic dysfunction. STZ challenge prompted reduced respiratory exchange ratio (RER), dampened fractional shortening, ejection fraction, increased LV end systolic and diastolic diameters, cardiac remodeling, cardiomyocyte contractile and intracellular Ca2+ defects (depressed peak shortening and maximal velocity of shortening/relengthening, prolonged relengthening, dampened intracellular Ca2+ rise and clearance), myocardial ultrastructural injury, oxidative stress, apoptosis and mitochondrial damage, the effects of which were overtly attenuated and accentuated by ALDH2 OE and KO, respectively. Immunoblotting revealed downregulated mitochondrial proteins PPARγ coactivator 1α (PGC-1α) and UCP-2, Ca2+ regulatory proteins including SERCA and Na+-Ca2+ exchanger, elevated phospholamban, dampened autophagy and mitophagy (LC3B ratio, TOM20, Parkin, FUNDC1 and BNIP3), disrupted phosphorylation of Akt, GSK3β and Foxo3a, and elevated PTEN phosphorylation, the effect of which was reversed and worsened by ALDH2 OE and KO, respectively (except FUNDC1 and BNIP3). In vivo and in vitro data revealed that novel ALDH2 activator torezolid/Alda-1 protected against STZ or high glucose-induced cardiac anomalies, the effect was nullified by inhibition of Akt, GSK3β, Parkin and mitochondrial coupling. Our data discerned a vital role for ALDH2 in diabetic cardiomyopathy possibly through regulation of Akt, GSK3β activation, parkin mitophagy and mitochondrial function.

ALDH2 polymorphism, alcohol intake and the attributable burden of cancer in East Asia: systematic review, meta-analysis, and modeling study

PURPOSE

To estimate the burden of alcohol-attributable cancer in East Asian populations accounting for aldehyde dehydrogenase-2 (ALDH2) genotype-specific cancer risk and alcohol exposure.

METHODS

We conducted a systematic review and meta-analysis of eight databases on cancer risk to derive alcohol dose-response curves by ALDH2 genotype. A simulation-based approach using the Global Burden of Disease (GBD) modeling framework was applied to estimate the population attributable fraction, incidence, and disability-adjusted life-years (DALYs) lost to alcohol-attributable cancer.

RESULTS

We included 34 studies (66,655 participants) from China, Japan, and South Korea in the meta-analysis. Alcohol dose-response curves for liver, esophageal, and oral cavity/pharynx cancer showed an increased risk for people with the inactivated ALDH2 genetic polymorphism, resulting in a higher burden of alcohol-attributable cancer compared to GBD estimates. Our methods estimated annual incidence of cancer of 230,177 cases, an underestimate of 69,596 cases compared to GBD estimates. Similarly, total DALYs lost annually were underestimated by 1.20 million.

CONCLUSIONS

The burden of liver, esophageal, and oral cavity/pharynx cancer attributable to alcohol is underestimated in populations with the ALDH2 genetic polymorphism when compared to current estimates.

Impact of common ALDH2 inactivating mutation and alcohol consumption on Alzheimer's disease

Aldehyde dehydrogenase 2 (ALDH2) is an enzyme found in the mitochondrial matrix that plays a central role in alcohol and aldehyde metabolism. A common ALDH2 polymorphism in East Asians descent (called ALDH2*2 or E504K missense variant, SNP ID: rs671), present in approximately 8% of the world's population, has been associated with a variety of diseases. Recent meta-analyses support the relationship between this ALDH2 polymorphism and Alzheimer's disease (AD). And AD-like pathology observed in ALDH2-/- null mice and ALDH2*2 overexpressing transgenic mice indicate that ALDH2 deficiency plays an important role in the pathogenesis of AD. Recently, the worldwide increase in alcohol consumption has drawn attention to the relationship between heavy alcohol consumption and AD. Of potential clinical significance, chronic administration of alcohol in ALDH2*2/*2 knock-in mice exacerbates the pathogenesis of AD-like symptoms. Therefore, ALDH2 polymorphism and alcohol consumption likely play an important role in the onset and progression of AD. Here, we review the data on the relationship between ALDH2 polymorphism, alcohol, and AD, and summarize what is currently known about the role of the common ALDH2 inactivating mutation, ALDH2*2, and alcohol in the onset and progression of AD.

Progression of Carotid Intima-Media Thickness Partly Indicates the Prevention of Hypertension among Older Individuals in the General Population

Structural atherosclerosis, as evaluated by carotid intima-media thickness (CIMT), is reported to be positively associated with hypertension. However, angiogenesis, which plays an important role in the progression of structural atherosclerosis, prevents hypertension by reducing peripheral vascular resistance. These associations evoke a contradiction: characteristics associated with the progression of structural atherosclerosis, which is related to hypertension, might prevent hypertension. To clarify novel mechanisms underlying the association between structural atherosclerosis and hypertension, multifaceted analyses are necessary. We performed several epidemiological studies based on this concept. This study summarizes those epidemiological studies and adds some discussion. Studies focusing on circulating CD34-positive cells, single-nucleotide polymorphisms (SNPs) of vascular endothelial growth factor (VEGF), SNPs in BRACA1-associated protein (BRAP), platelets, human T-cell leukemia virus type 1 (HTLV-1), and SNPs in aldehyde dehydrogenase 2 (ALDH2) have shown that active endothelial repair, which leads to the progression of structural atherosclerosis, helps prevent hypertension. These associations indicate that the progression of structural atherosclerosis could act as a marker of angiogenesis, which reduces peripheral vascular resistance. In general, a positive association between structural atherosclerosis and hypertension has been reported. However, the progression of structural atherosclerosis could act as a marker of activity that prevents hypertension via reductions in peripheral vascular resistance.

Astragaloside IV Blunts Epithelial-Mesenchymal Transition and G2/M Arrest to Alleviate Renal Fibrosis via Regulating ALDH2-Mediated Autophagy

Previous studies show that astragaloside IV (ASIV) has anti-renal fibrosis effects. However, its mechanism remains elusive. In this study, we investigated the anti-fibrosis mechanisms of ASIV on chronic kidney disease (CKD) in vivo and in vitro. A CKD model was induced in rats with adenine (200 mg/kg/d, i.g.), and an in vitro renal fibrosis model was induced in human kidney-2 (HK-2) cells treated with TGF-β1. We revealed that ASIV significantly alleviated renal fibrosis by suppressing the expressions of epithelial-mesenchymal transition (EMT)-related proteins, including fibronectin, vimentin, and alpha-smooth muscle actin (α-SMA), and G2/M arrest-related proteins, including phosphorylated p53 (p-p53), p21, phosphorylated histone H3 (p-H3), and Ki67 in both of the in vivo and in vitro models. Transcriptomic analysis and subsequent validation showed that ASIV rescued ALDH2 expression and inhibited AKT/mTOR-mediated autophagy. Furthermore, in ALDH2-knockdown HK-2 cells, ASIV failed to inhibit AKT/mTOR-mediated autophagy and could not blunt EMT and G2/M arrest. In addition, we further demonstrated that rapamycin, an autophagy inducer, reversed the treatment of ASIV by promoting autophagy in TGF-β1-treated HK-2 cells. A dual-luciferase report assay indicated that ASIV enhanced the transcriptional activity of the ALDH2 promoter. In addition, a further molecular docking analysis showed the potential interaction of ALDH2 and ASIV. Collectively, our data indicate that ALDH2-mediated autophagy may be a novel target in treating renal fibrosis in CKD models, and ASIV may be an effective targeted drug for ALDH2, which illuminate a new insight into the treatment of renal fibrosis and provide new evidence of pharmacology to elucidate the anti-fibrosis mechanism of ASIV in treating renal fibrosis.

Activation of aldehyde dehydrogenase-2 improves ischemic random skin flap survival in rats

Objective

Random skin flaps have many applications in plastic and reconstructive surgeries. However, distal flap necrosis restricts wider clinical utility. Mitophagy, a vital form of autophagy for damaged mitochondria, is excessively activated in flap ischemia/reperfusion (I/R) injury, thus inducing cell death. Aldehyde dehydrogenase-2 (ALDH2), an allosteric tetrameric enzyme, plays an important role in regulating mitophagy. We explored whether ALDH2 activated by N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide (Alda-1) could reduce the risk of ischemic random skin flap necrosis, and the possible mechanism of action.

Methods

Modified McFarlane flap models were established in 36 male Sprague-Dawley rats assigned randomly to three groups: a low-dose Alda-1 group (10 mg/kg/day), a high-dose Alda-1 group (20 mg/kg/day) and a control group. The percentage surviving skin flap area, neutrophil density and microvessel density (MVD) were evaluated on day 7. Oxidative stress was quantitated by measuring the superoxide dismutase (SOD) and malondialdehyde (MDA) levels. Blood perfusion and skin flap angiogenesis were assessed via laser Doppler flow imaging and lead oxide-gelatin angiography, respectively. The expression levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α), vascular endothelial growth factor (VEGF), ALDH2, PTEN-induced kinase 1 (PINK1), and E3 ubiquitin ligase (Parkin) were immunohistochemically detected. Indicators of mitophagy such as Beclin-1, p62, and microtubule-associated protein light chain 3 (LC3) were evaluated by immunofluorescence.

Results

Alda-1 significantly enhanced the survival area of random skin flaps. The SOD activity increased and the MDA level decreased, suggesting that Alda-1 reduced oxidative stress. ALDH2 was upregulated, and mitophagy-related proteins (PINK1, Parkin, Beclin-1, p62, and LC3) were downregulated, indicating that ALDH2 inhibited mitophagy through the PINK1/Parkin signaling pathway. Treatment with Alda-1 reduced neutrophil infiltration and expressions of inflammatory cytokines. Alda-1 significantly upregulated VEGF expression, increased the MVD, promoted angiogenesis, and enhanced blood perfusion.

Conclusion

ALDH2 activation can effectively enhance random skin flap viability via inhibiting PINK1/Parkin-dependent mitophagy. Moreover, enhancement of ALDH2 activity also exerts anti-inflammatory and angiogenic properties.

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.

ALDH2 ameliorates ethanol-induced gastric ulcer through suppressing NLPR3 inflammasome activation and ferroptosis

Gastric ulcer (GU) is a prevalent and life-threating gastrointestinal disorder. Aldehyde dehydrogenase 2 (ALDH2) is a pivotal component of alcohol metabolism which has been supported to suppress oxidative stress-elicited DNA damage in gastric mucosa cells. Nonetheless, whether ALDH2 is also involved in GU remains indistinct. Firstly, HCl/ethanol-induced experimental rat GU model was successfully established. RT-qPCR and western blot tested ALDH2 expression in rat tissues. Following the addition of ALDH2 activator Alda-1, gastric lesion area and index were measured. H&E staining detected the histopathology of gastric tissues. ELISA examined the levels of inflammatory mediators. Alcian blue staining evaluated mucus production of gastric mucosa. Oxidative stress levels were estimated by corresponding kits and western blot. Western blot examined the expression of NLRP3 inflammasome- and ferroptosis-related proteins. Prussian blue staining and corresponding assay kits measured ferroptosis. In ethanol-treated GES-1 cells, NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, iron content, ferroptosis, inflammation and oxidative stress were detected as aforementioned above. In addition to that, DCFH-DA staining examined ROS generation. The experimental data corroborated that ALDH2 expression was declined in the tissues of HCl/ethanol-treated rats. Alda-1 ameliorated HCl/ethanol-stimulated gastric mucosal damage, inflammatory response, oxidative stress, NLRP3 inflammasome activation and ferroptosis in rats. Also, the suppressive role of ALDH2 in inflammatory response and oxidative stress was reversed by ferroptosis activator erastin or NLRP3 activator nigericin in HCl/ethanol-challenged GES-1 cells. To be summarized, ALDH2 might play the protective role in the process of GU.

ALDH2 promotes cancer stemness and metastasis in colorectal cancer through activating β-catenin signaling

Colorectal cancer (CRC) is the primary cause of death from gastrointestinal cancers. Aldehyde dehydrogenase 2 (ALDH2), a crucial mitochondrial enzyme for the oxidative pathway of alcohol metabolism, plays a dual role in cancer progression. In some cancers, it is tumor suppressive; in others, it drives cancer progression. However, whether targeting ALDH2 has any therapeutic implications or prognostic value in CRC is still unclear. Here, we investigated the role of ALDH2 in CRC progression by targeting its enzymatic activity rather than gene expression. We found that inhibiting ALDH2 by CVT-10216 and daidzein significantly decrease migration and stemness properties of both DLD-1 and HCT 116 cells, whereas activating ALDH2 by Alda-1 enhances migration rate. Concomitantly, ALDH2 inhibition by both CVT-10216 and daidzein downregulates the mRNA levels of fibronectin, snail, twist, MMP7, CD44, c-Myc, SOX2, and OCT-4, which are oncogenic in the advanced stage of CRC. Furthermore, Gene Set Enrichment Analysis (GSEA) on ALDH2 co-expressed genes from The Cancer Genome Atlas (TCGA) revealed that MYC target gene sets are upregulated. We found that ALDH2 inhibition decreased the nuclear protein levels of pGSK3β serine 9 and c-Myc. This suggests that ALDH2 probably targets β-catenin signaling in CRC cells. Together, our results demonstrate the prognostic value of ALDH2 in CRC as it regulates both CRC stemness and migration. Our findings also propose that the plant-derived isoflavone daidzein could be a potential chemotherapeutic drug targeting ALDH2 in CRC.

p53 protects against alcoholic fatty liver disease via ALDH2 inhibition

The tumor suppressor p53 is critical for tumor suppression, but the regulatory role of p53 in alcohol-induced fatty liver remains unclear. Here, we show a role for p53 in regulating ethanol metabolism via acetaldehyde dehydrogenase 2 (ALDH2), a key enzyme responsible for the oxidization of alcohol. By repressing ethanol oxidization, p53 suppresses intracellular levels of acetyl-CoA and histone acetylation, leading to the inhibition of the stearoyl-CoA desaturase-1 (SCD1) gene expression. Mechanistically, p53 directly binds to ALDH2 and prevents the formation of its active tetramer and indirectly limits the production of pyruvate that promotes the activity of ALDH2. Notably, p53-deficient mice exhibit increased lipid accumulation, which can be reversed by ALDH2 depletion. Moreover, liver-specific knockdown of SCD1 alleviates ethanol-induced hepatic steatosis caused by p53 loss. By contrast, overexpression of SCD1 in liver promotes ethanol-induced fatty liver development in wild-type mice, while it has a mild effect on p53-/- or ALDH2-/- mice. Overall, our findings reveal a previously unrecognized function of p53 in alcohol-induced fatty liver and uncover pyruvate as a natural regulator of ALDH2.

Aged Garlic Extract Prevents Alcohol-Induced Cytotoxicity through Induction of Aldehyde Dehydrogenase 2 in the Liver of Mice

SCOPE

Acetaldehyde is a highly toxic primary metabolite of ethanol, and converts to nontoxic acetic acid by aldehyde dehydrogenase (ALDH). Accumulation of acetaldehyde causes significant damage to human body. Aged garlic extract (AGE) is a functional food material and possesses various health beneficial effects. This study investigates whether AGE contributes to acetaldehyde detoxification through ALDH induction and its underlying mechanism.

METHODS AND RESULTS

C57BL/6J mice are orally administrated 10-1000 mg kg^-1 body weight (BW) of AGE for 1 week before ethanol administration. AGE suppresses ethanol-caused accumulation of acetaldehyde level in the plasma through inducing mitochondrial ALDH2 but not cytosolic ALDH1A1. AGE also induces antioxidant enzymes, heme oxygenase-1, and NAD(P)H:quinone oxidoreductase 1, resulting in prevention of lipid peroxidation in the liver. In HepG2 cells, AGE prevents ethanol- and acetaldehyde-caused cytotoxicity. AGE induces mitochondrial ALDH2 through activating nuclear factor-erythroid 2-related factor 2 (Nrf2). AGE inhibits protein degradation of Nrf2 and enhances protein degradation of kelch-like ECH-associated protein 1. Furthermore, S-allyl cysteine and S-allyl mercaptocysteine as the bioactive compounds in AGE also induce ALDH2 and Nrf2.

CONCLUSION

AGE prevents acetaldehyde-induced hepatotoxicity through enhancing acetaldehyde detoxification through Nrf2-dependent induction of mitochondrial ALDH2.

The role of acetaldehyde dehydrogenase 2 in the pathogenesis of liver diseases

Common liver tissue damage is mainly due to the accumulation of toxic aldehydes in lipid peroxidation under oxidative stress. Cumulative toxic aldehydes in the liver can be effectively metabolized by acetaldehyde dehydrogenase 2 (ALDH2), thereby alleviating various liver diseases. Notably, gene mutation of ALDH2 leads to impaired ALDH2 enzyme activity, thus aggravating the progress of liver diseases. However, the relationship and specific mechanism between ALDH2 and liver diseases are not clear. Consequently, the review explains the relationship between ALDH2 and liver diseases such as alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), liver fibrosis and hepatocellular carcinoma (HCC). In addition, this review also discusses ALDH2 as a potential therapeutic target for various liver diseases,and focuses on summarizing the regulatory mechanism of ALDH2 in these liver diseases.

Lipidomic changes of cerebral cortex in aldehyde dehydrogenase-2 knock-in heterozygote mice after chronic alcohol exposure

Introduction

Alcohol is the main legal drug in the world, and excessive consumption of alcohol seriously damages the morphological structure and function of various organs. The insufficiency of an essential enzyme in ethanol metabolism, aldehyde dehydrogenase-2 (ALDH2), will aggravate the alcohol-induced brain injury. The effect of ALDH2 after chronic alcohol exposure on global lipid profiling of the brain remains unclear.

Methods

In this study, ALDH2*2 knock-in mice were fed the Lieber-DeCarli liquid diet containing ethanol for 8 weeks. Blood alcohol and acetaldehyde levels were examined, and the mice were tested through novel object recognition and the Y-maze test to evaluate cognitive impairment toward the end of the study. The lipidome profiling of cerebral cortex samples was investigated using a lipidomics method based on ultra-high performance liquid tandem chromatography quadrupole time of flight mass spectrometry (UHPLC-QTOFMS).

Results and Discussion

Compared with similarly treated wild-type (WT) mice, ALDH2*2 mice exhibited poor cognitive performance, though the result did not achieve statistical significance. The lipidomics results indicated that 74 differential lipid species were selected in WT mice, of which 57 species were up-regulated, and 17 were down-regulated. Moreover, 99 differential lipids were identified in ALDH2*2 mice, of which 73 were up-regulated, and 26 were down-regulated. For ALDH2*2 mice, the number of changed significantly glycerophospholipids (GPs) subtypes was lower than that of WT mice. Interestingly, compared with WT mice, a lower proportion of polyunsaturated fatty acids (PUFAs) was found in ALDH2*2 mice. Collectively, the results provide clear evidence for a lipidomic signature of marked changes in the cerebral cortex of ALDH2*2 mice after chronic alcohol exposure.

Highlights

• The cerebral cortex of heterozygous ALDH2*2 mice showed more significant changes in lipidome profiles after chronic alcohol exposure than wild-type mice.• Most lipids were significantly up-regulated in both groups of mice, whereas the increase in TAG was restricted to WT mice.• For ALDH2*2 mice, GPs substances changed significantly, and SHexCer and SM subclasses in sphingolipids also deserved attention.

Loss of ALDH2 aggravates mitochondrial biogenesis disorder in cardiac myocytes induced by TAC

Heart failure is one of the major fatal diseases and mitochondrial biogenesis is an important compensatory mechanism in the process of heart failure. Aldehyde dehydrogenase 2(ALDH2) is an important endogenous cardiac protective factor in mitochondria, but its role in mitochondrial biogenesis of cardiomyocytes remains unknown. In our study, transverse aorta constriction(TAC)-induced heart failure model was established in ALDH2-/- mice and wild-type mice. The cardiac function was examined by echocardiography at 4 weeks after operation. The myocardial tissue was stained by HE. The mitochondria morphology was observed using electron microscope, and the ATP content, Sirt1,PGC-1α and NRF1 expression were measured. Compared with wild-type mice, the cardiac function of ALDH2 -/- mice decreased significantly at 4 weeks after TAC. The proportion of mitochondrial area and mitochondrial crest/mitochondrial ratio decreased in the ALDH2-/- group after TAC. The ATP content decreased in ALDH2 -/- mice at 4 weeks after TAC. In the meantime, the expression of PGC-1α,Sirt 1 and NRF1 decreased in the ALDH2-/- TAC group compared with wild type TAC group.Neonatal rat cardiomyocytes were cultured and stretched. Cardiomyocytes were treated with the activator of ALDH2(Alda-1), Sirt1-SiRNA and PGC-1α-siRNA, respectively. The mitochondrial structure of cardiomyocytes was observed by transmission electron microscopy. The levels of PGC-1α,NRF-1 and Tfam were measured by Western blot.Mitochondrial biogenesis was enhanced in stretch cardiomyocytes treated with Alda-1.When cardiomyocytes were treated with Sirt1-SiRNA or PGC1α-SiRNA, the effect of Alda-1 in promoting mitochondrial biogenesis was attenuated.Therefore, these results suggested that the loss of ALDH2 aggravates mitochondrial biogenesis disorder in cardiac myocytes induced by TAC. Alda-1 could promote mitochondrial biogenesis in stretched cardiomyocytes, and this effect depends on Sirt1/PGC-1α pathway.

Alda-1 ameliorates air embolism-induced acute lung injury

OBJECTIVE

Evidence suggests that aldehyde dehydrogenase 2 (ALDH2) offers protection against damage caused by oxidative stress in diverse rodent models. Nonetheless, the effect of Alda-1, a compound that activates ALDH2, on acute lung injury (ALI) induced by air embolism (AE) remains unclear. The objective of this study was to explore the protective effects of Alda-1 in ALI induced by AE.

METHODS

A rat model of in situ isolated perfused lung was established to investigate AE-induced ALI. Air was infused into the pulmonary artery at 0.25 mL/min for 1 minute. Before inducing AE, different doses (10, 20, or 30 mg/kg) of Alda-1 were given through intraperitoneal injection. Pathological changes in lung tissue were assessed using hematoxylin-eosin staining. We performed Western blot analysis to assess the protein levels of ALDH2,4-hydroxy-trans-2-nonenal (4-HNE), Bcl-2, caspase-3, phosphatidylinositol 3-kinase (PI3K), Akt, IκB-α, and nuclear NF-κB.

RESULTS

Notably, AE results were demonstrated as harmful to the lungs, which is evidenced by intensified lung edema and disruption of lung tissue structure. Furthermore, AE caused a decrease in ALDH2 expression, increased accumulation of 4-HNE and MDA, infiltration of neutrophils, increased production of inflammatory cytokines, apoptosis, and upregulation of the PI3K/Akt and NF-κB signaling pathways within the lungs. Administration of a 20 mg/kg dose of Alda-1 alleviated the detrimental effects induced by AE.

CONCLUSION

Alda-1 shows promise in mitigating AE-induced ALI, possibly through the upregulation of ALDH2 expression and suppression of the PI3K/Akt and NF-κB signaling pathways. Further research is warranted to validate these findings and to explore their translational potential in human subjects.

Aldehyde dehydrogenase 2 and NOD-like receptor thermal protein domain associated protein 3 inflammasome in atherosclerotic cardiovascular diseases: A systematic review of the current evidence

Inflammation and dyslipidemia underlie the pathological basis of atherosclerosis (AS). Clinical studies have confirmed that there is still residual risk of atherosclerotic cardiovascular diseases (ASCVD) even after intense reduction of LDL. Some of this residual risk can be explained by inflammation as anti-inflammatory therapy is effective in improving outcomes in subjects treated with LDL-lowering agents. NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome activation is closely related to early-stage inflammation in AS. Aldehyde dehydrogenase 2 (ALDH2) is an important enzyme of toxic aldehyde metabolism located in mitochondria and works in the metabolism of toxic aldehydes such as 4-HNE and MDA. Despite studies confirming that ALDH2 can negatively regulate NLRP3 inflammasome and delay the development of atherosclerosis, the mechanisms involved are still poorly understood. Reactive Oxygen Species (ROS) is a common downstream pathway activated for NLRP3 inflammasome. ALDH2 can reduce the multiple sources of ROS, such as oxidative stress, inflammation, and mitochondrial damage, thereby reducing the activation of NLRP3 inflammasome. Further, according to the downstream of ALDH2 and the upstream of NLRP3, the molecules and related mechanisms of ALDH2 on NLRP3 inflammasome are comprehensively expounded as possible. The potential mechanism may provide potential inroads for treating ASCVD.

ALDH2 rs671 variant allele is associated with higher energy intake in middle-aged and elderly Japanese who routinely consume alcohol

BACKGROUND

According to recent reports, individuals with reduced aldehyde dehydrogenase activity may require more energy for the detoxification of aldehydes. Aldehyde dehydrogenase 2 (ALDH2), an ALDH isozyme, is responsible for detoxifying acetaldehyde, an intermediate metabolite of ethanol. Because the variant allele of the rs671 polymorphism of ALDH2 results in a substantial reduction in enzymatic activity, carriers of this variant allele may have a higher energy demand when consuming alcohol than non-carriers. However, no studies have evaluated this phenomenon to date.

METHOD

To test the hypothesis, we statistically examined the interactive effects between the rs671 and ethanol consumption on energy intake using cross-sectional data from a population-based cohort study, the Japan Multi-Institutional Collaborative Cohort Study, which was conducted in Saga city between 2005-2007 (N = 12,068).

RESULTS

General linear regression models adjusted for age, sex, ethanol consumption, current smoking status, years of education, dietary restriction, medical history, and physical activity level revealed that energy intake was higher in variant allele carriers than in non-carriers among individuals with alcohol drinking habits, whereas no such correlation was observed among those without drinking habits (≤2 g ethanol/day) (p = 0.03 for interaction between rs671 and ethanol consumption). Energy intake excluding energy from alcoholic beverages, carbohydrate intake, protein intake, and fat intake, showed similar tendencies (p for interaction = 0.01, 0.01, 0.04, and 0.07, respectively).

CONCLUSIONS

These findings support the hypothesis that increased energy intake is required for the detoxification of aldehydes in individuals with low ALDH activity. This epidemiological evidence provides a possible scientific basis for understanding aldehyde detoxification mechanisms and suggests a novel phenotype of the ALDH2 rs671 polymorphism.

ALDH2 rs671 Polymorphism Likely a Risk Factor for Hemorrhagic Stroke: A Hospital-Based Study

Background

Hypertension is the main risk factor for hemorrhagic stroke. Aldehyde dehydrogenase 2 (ALDH2) may inhibit the occurrence of hypertension by anti-oxidative stress and vascular dilation. The purpose was to investigate the relationship of ALDH2 polymorphisms with hemorrhagic stroke in Hakka Chinese.

Methods

A total of 329 patients with hemorrhagic stroke and 515 controls were enrolled, and medical records (smoking and drinking history, hypertension, and diabetes) were collected. The genotypes of ALDH2 rs671 of the two groups were detected and analyzed.

Results

The proportion of the ALDH2 rs671 G/G, G/A, and A/A genotype in patients with hemorrhagic stroke was 55.9%, 37.4%, and 6.7%, respectively, while those were 65.0%, 30.7%, and 4.3% in controls, respectively. There was statistically significant difference in ALDH2 rs671 genotypes distribution (P=0.021) and alleles distribution (P=0.005) between patients and controls. Among hemorrhagic stroke patients, no statistically significant differences were observed between patients with ALDH2 different genotypes. Logistic regression analysis showed that there was significantly high risk of hemorrhagic stroke in men (male vs female: adjusted OR 1.711, 95% CI 1.154-2.538, P=0.008), the presence of hypertension (with vs without hypertension: adjusted OR 16.095, 95% CI 10.958-23.641, P<0.001), and the presence of ALDH2 rs671 G/A genotype (G/A vs G/G: adjusted OR 1.679, 95% CI 1.151-2.450, P=0.007) or A/A genotype (A/A vs G/G: adjusted OR 2.516, 95% CI 1.132-5.591, P=0.024).

Conclusion

ALDH2 rs671 polymorphism likely a risk factor for hemorrhagic stroke.

Emerging bone marrow failure syndromes- new pieces to an unsolved puzzle

Inherited bone marrow failure (BMF) syndromes are genetically diverse - more than 100 genes have been associated with those syndromes and the list is rapidly expanding. Risk assessment and genetic counseling of patients with recently discovered BMF syndromes is inherently difficult as disease mechanisms, penetrance, genotype-phenotype associations, phenotypic heterogeneity, risk of hematologic malignancies and clonal markers of disease progression are unknown or unclear. This review aims to shed light on recently described BMF syndromes with sparse concise data and with an emphasis on those associated with germline variants in ADH5/ALDH2, DNAJC21, ERCC6L2 and MECOM. This will provide important data that may help to individualize and improve care for these patients.

[ALDH2 attenuates LPS-induced increase of brain microvascular endothelial cell permeability by promoting fusion and inhibiting fission of the mitochondria]

OBJECTIVE

To investigate the effect of aldehyde dehydrogenase 2 (ALDH2) on lipopolysaccharide (LPS)- induced damage of mouse brain microvascular endothelial barrier and explore the role of mitochondrial fusion and fission in maintaining the integrity of endothelial barrier.

METHODS

Mouse brain microvascular endothelial cells were treated with 1 μg/ mL LPS for 24 h with or without pretreatment with 20 μmol/mL Alda-1 (a ALDH2 agonist) for 1 h. The changes in cell viability were assessed using cell counting Kit-8 (CCK8) assay, and the cell permeability was evaluated using transendothelial cell resistance (TEER) and FITC-Dextran assay. The level of oxidative stress in the cells was assessed by detecting the levels of malondialdehyde (MDA) and superoxide dismutase (SOD), and the content of reactive oxygen species (ROS) was detected using a superoxide anion fluorescent probe (DHE). Western blotting was performed to detect the expressions of ALDH2, tight junction proteins ZO-1 and occludin, and mitochondrial fusion- and division-related proteins Mfn2, OPA1, Drp1 and Fis1.

RESULTS

Compared with the untreated cells, the cells treated with LPS showed significantly decreased TEER, increased FITC-dextran leakage, MDA content and ROS production, decreased SOD activity expressions of ALDH2, ZO-1, occludin, Mfn2 and OPA1, and increased expressions of Drp1 and Fis1 (P < 0.05). Pretreatment with Alda-1 prior to LPS exposure strongly suppressed the increase of endothelial cell membrane permeability, reduced ROS production, increased the expressions of ALDH2, ZO-1, occludin, OPA1 and Mfn2, and lowered the expressions of Drp1 and Fis1 (P < 0.05).

CONCLUSION

ALDH2 can alleviate LPS-induced damage of brain microvascular endothelial cell barrier by inhibiting the mitochondrial ROS production and promoting mitochondrial fusion and inhibiting mitochondrial fission.

Identifying the Therapeutic and Prognostic Role of the CD8+ T Cell-Related Gene ALDH2 in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSC) is a widely known malignancy which is usually diagnosed late and has a poor prognosis. This study focuses on finding a new gene linked with CD8+ T cell infiltration as a prognostic marker for patients with HNSC. Differential analysis of transcriptomic data was performed between HNSC and control tissues from TCGA and GEO database. The CD8+ T cell infiltration score was quantified using single-sample gene set enrichment analysis (ssGSEA). Weighted gene co-expression network analysis (WGCNA) algorithms were used to identify key modules associated with CD8+ T cell infiltration. Kaplan-Meier (K-M) survival analysis was used to compare overall survival (OS) between the 2 groups. Univariate and multivariate Cox analyses were used to assess independent prognostic markers. The results showed CD8+ T cell infiltration score was an independent favorable prognostic marker in HNSC. Differential analysis and WGCNA identified 93 differential gene related to high CD8+ T infiltration. Amog the 93 genes, ALDH2 was an independent favorable prognostic marker in HNSC. ALDH2 expression was found to be much lower in HNSC, and patients with low ALDH2 expression had higher T stage and N stage. The correlation analysis showed that ALDH2 was linked with immune cell infiltration in the tumor microenvironment of HNSC. Patients having increased expression of ALDH2 tend to be sensitive to immune checkpoint inhibitors (ICIs). In addition, we showed the relationship between ALDH2 expression and chemotherapeutic drug sensitivity. In conclusion, this study identified ALDH2 as a prognostic marker, associated with CD8+ T cell infiltration in HNSC.

High ALDH2 expression is associated with better prognosis in patients with gastric cancer

The relationship among alcohol, acetaldehyde, and gastric cancer (GC) is a very interesting research direction. Although many studies have focused on the correlation between ALDH2 polymorphism and GC, ALDH2 expression in GC and its relationship with the prognosis of GC patients remain to be fully understood. To explore these, 455 GC cases were included in this study. The relationships of ALDH2 expression with patients' survival and clinicopathological characteristics were assessed. The immune infiltration characteristics of ALDH2 in GC were also analyzed. Furthermore, the gene regulatory network and functional pathways of ALDH2 in GC were investigated. We found that high expression of ALDH2 was associated with better prognosis in GC patients. GC patients with high ALDH2 expression had a lower degree of pathological malignancy, consistent with our hypothesis that ALDH2 may play as a tumor suppressor role in GC. Mechanistically, ALDH2 may cooperate with genes such as C5orf32, TSPAN8 and RILP to inhibit GC progression via regulating multiple signaling pathways and chemical carcinogenesis. Therefore, our study suggested that ALDH2, an important variant gene in Asians, might serve as a prognostic marker and a potential therapeutic target for patients with GC.

Single Nucleotide Polymorphisms of ADH1B, ADH1C and ALDH2 Genes in 235 People Living in Thai Nguyen Province of Vietnam

OBJECTIVE

ADH1B, ADH1C and ALDH2 genes are mainly responsible for alcohol metabolism in the body. Several single nucleotide polymorphisms (SNPs) of these genes have been reported to be associated with alcohol dependence and are considered risk factors for various human diseases. This study aims to identify the prevalence of three SNPs of ADH1B (rs1229984), ADH1C (rs698) and ALDH2 (rs671) in 235 unrelated individuals living in Thai Nguyen province, the northeast region of Vietnam.

METHODS

The target genotypes were identified by using PCR direct sequencing, and their frequencies were compared to previous reports.

RESULT

Our data showed that allele frequencies of ADH1B*2, ADH1C*2 and ALDH2*2 were 68.8%, 8.3% and 20.4%, respectively. The ADH1B*2 and ADH1C*2 frequencies were similar to those of the Kinh ethnic individuals living in the south region of Vietnam, while the ALDH2*2 frequency was higher. Compared to data from other countries, ADH1B*2 frequency is similar to the Philippines (60.5%) and Mongolia (62.9%) but significantly different from the other populations. The ADH1C*2 frequency is not so different compared to Japanese (5.7%) and Chinese (7.1%) but is quite different in other populations. ALDH2*2 frequency was lower than Japanese (29.3%), Indonesian (30%) and higher than other countries. Regarding the risk of alcoholism, the percentage of Vietnamese people in this study with genotypes related to alcohol dependence is 8.1%. In contrast, the carrier has genotypes protecting against alcoholism with high frequency, 91.9%. Among them, the individuals can cause high acetaldehyde accumulation accounting for 33.2%.

CONCLUSION

This study helps to understand the genetic polymorphisms of alcohol metabolism genes in the community living in Thai Nguyen province, northeast of Vietnam, and provides valuable scientific data relating to alcohol consumption behavior as well as public health protection.

A novel and cost-efficient allele-specific PCR method for multiple SNP genotyping in a single run

Cost-effective methods for DNA genotyping were needed because single nucleotide polymorphisms (SNPs) were essential biomarkers associated with many diseases. Allele-specific PCR (AS-PCR) has the advantages of mature instruments and high sensitivity. But conventional AS-PCR needs to multiply the number of reactions or primers for multiple targets, which complicates the operation and increases the cost. Herein, we proposed a novel AS-PCR method for multiple SNP genotyping in a single run. Wild-type allele-specific primer (WT primer) was designed for each target gene. The sample and WT primers only needed to undergo multiplexed AS-PCR once simultaneously. After AS-PCR, the concentration of remaining primers varied among the samples of each genotype combination, due to the different matching performance between template and WT primers. The remaining primers then triggered multiplexed molecular beacon-rolling circle amplification, and the molecular beacons labelled with different fluorescent dyes corresponded to different targets. The fluorescence ratios of the sample to the positive control were used as the genotyping indexes. This method was able to detect samples with concentrations as low as 10 fM. We successfully applied the method to the multiple genotyping of 23 hair root samples for ADH1B and ALDH2 genes, obtaining completely consistent results with sequencing. The reagent cost was 0.6 dollar for one sample, showing a good cost performance. This proposed approach had a great application prospect in simultaneously rapid and accurate genotyping of multi-SNPs, and provided a new method for personalized health management.

The association of AGER and ALDH2 gene polymorphisms with diabetic retinopathy

PURPOSE

To evaluate the possible associations between AGER (rs1051993, rs2070600) and ALDH2 (rs671) gene polymorphisms with nonproliferative (NPDR) and proliferative (PDR) diabetic retinopathy, in a well-defined Greek population.

MATERIALS

66 NPDR patients and 57 PDR patients participated in our study, along with 156 age- and gender-matched healthy-control subjects (CL). All the participants underwent a complete ophthalmological examination, while clinical and demographic data were collected. Furthermore, they were genotyped for the studied polymorphisms.

RESULTS

No significant differences were detected among the studied groups regarding the participants' age and gender status. We found that the ALDH2 AA genotype was significantly more frequent in PDR patients than in CL (p = 0.014). Furthermore, between NPDR and PDR groups, the AGER rs1051993 GT and TT genotype frequencies were significantly elevated in PDR patients (p < 0.0001 and 0.04, respectively). Moreover, we demonstrated that the heterozygous GT genotype in DR patients is accompanied by 71.11 times higher risk of developing PDR (OR = 71.11: 95% CI- 4.14-1215.2), while the homozygous TT genotype is associated with 12.71 times elevated risk for PDR development (OR = 12.71: 95% CI- 0.63-254.1).

CONCLUSIONS

We documented that the ALDH2 AA and AGER rs1051993 GT and TT genotypes were observed significantly more frequently in PDR Greek diabetic patients. Our findings also support the genetic theory, suggesting that heritability is significantly implicated in the development of DR, providing additional evidence in the understanding of DR pathogenesis.

Aldehyde dehydrogenase 2 rs671 polymorphism and multiple diseases: protocol for a quantitative umbrella review of meta-analyses

BACKGROUND

The mutant allele (*2) of aldehyde dehydrogenase type 2 (ALDH2) caused by a single nucleotide variant (rs671) inhibits enzymatic activity and is associated with multiple diseases. In recent years, an explosive number of original studies and meta-analyses have been conducted to examine the associations of ALDH2 rs671 polymorphism with diseases. Due to conflicting results, the overall associations of ALDH2 rs671 polymorphism and multiple diseases remain unclear.

METHODS

A quantitative umbrella review will be conducted on meta-analyses of genetic association studies to examine the pleiotropic effects of ALDH2 rs671, mainly including cardio-cerebral vascular disease, diabetes mellitus, cancer, neurodegenerative disease, and alcohol-induced medical disease. A search of relevant literature according to comprehensive search strategies will be performed on studies published before July 1st, 2022 in PubMed, MEDLINE Ovid, Embase, Cochrane Database of Systematic Reviews, and Web of Science. Study selection, data extraction, methodology quality assessment, and strength of evidence assessment will be conducted by two reviewers independently and in duplicate. Included meta-analyses will be grouped by outcomes. Data conflicts and overlap between meta-analyses will be managed through updated standardized and customized methods including the calculation of CCA for study selection reference, application of Doi plots to assess small-study effects and others. Evidence from included meta-analyses will be quantitatively synthesized by overlap-corrected analyses and meta-analysis using primary studies.

DISCUSSION

This umbrella review is expected to generate systematic evidence on the association between ALDH2 rs671 and diseases. Specific approaches were developed to address key challenges in conducting an umbrella review, including assessment tools of methodology and evidence quality of meta-analyses, methods to manage overlap between meta-analyses, a "stop-light" plot to summarize key findings. These approaches provide applicable methods for future umbrella reviews of meta-analyses on genetic association studies.

TRIAL REGISTRATION

CRD42021223812.

Study protocol of brief intervention using gene polymorphism information for excessive drinking among Japanese college students and adults aged 20-30 years: a randomized controlled trial

Background

The alcohol-metabolizing enzyme aldehyde dehydrogenase 2 (ALDH2) is a carcinogenic acetaldehyde-degrading enzyme, and its low activity is a genetic constitution peculiar to East Asians. People with low alcohol dehydrogenase 1B activity (ADH1B*1/*1 genotype) have a high risk of developing head and neck cancer and alcoholism. The study aims to evaluate the effectiveness of brief interventions for excessive drinking among college students and adults in their 20s, including information on five constitutions that combine the ALDH2 and ADH1B genotypes.

Methods

Participants comprised university students and staff aged 20–30 years who had consumed ≥40 g (males) or ≥20 g (females) of pure alcohol; they were classified into intervention and control groups using a simple randomization method. Participants anonymously filled out questionnaires linked to identification numbers and recorded the drinking days and amounts on the drinking calendar. The intervention group will then be tested for genotype testing using saliva (5 types of combinations of ALDH2 and ADH1B enzyme activities); the result report will arrive approximately 1 month later. We will conduct a 30-min face-to-face or online intervention. The control group will be merely given the conventional materials, and genetic testing will be performed voluntarily after 6 months (end of study). The intervention group will undergo questionnaire surveys 1 month after the intervention and 3 and 6 months after baseline. Questionnaire surveys will be conducted 1, 3, and 6 months after baseline for the control group. The average amount of drinking before and after the intervention, attribute/baseline data between the two groups, and time-series data were compared using various analysis tools. For interventions, we engaged in dialog based on intervention materials that added genotyping content to the existing materials, result reports, baseline data, and drinking calendar records. Participants’ ingenuity is respected to support their drinking behavior and goal setting.

Discussion

Individual information on the genetic makeup of alcohol-metabolizing enzymes provided during the intervention is more personal and objective than general health information, especially in Japan, where the ALDH2 low activity rate is high. This information may be useful for health care and precautionary measures.

Trial registration

R000050379, UMIN000044148, Registered on June 1, 2021.

Scientific Title: Examination of simple intervention using genetic polymorphism information for excessive drinking.

Identification of novel proteins for lacunar stroke by integrating genome-wide association data and human brain proteomes

BACKGROUND

Previous genome-wide association studies (GWAS) have identified numerous risk genes for lacunar stroke, but it is challenging to decipher how they confer risk for the disease. We employed an integrative analytical pipeline to efficiently transform genetic associations to identify novel proteins for lacunar stroke.

METHODS

We systematically integrated lacunar stroke genome-wide association study (GWAS) (N=7338) with human brain proteomes (N=376) to perform proteome-wide association studies (PWAS), Mendelian randomization (MR), and Bayesian colocalization. We also used an independent human brain proteomic dataset (N=152) to annotate the new genes.

RESULTS

We found that the protein abundance of seven genes (ICA1L, CAND2, ALDH2, MADD, MRVI1, CSPG4, and PTPN11) in the brain was associated with lacunar stroke. These seven genes were mainly expressed on the surface of glutamatergic neurons, GABAergic neurons, and astrocytes. Three genes (ICA1L, CAND2, ALDH2) were causal in lacunar stroke (P < 0.05/proteins identified for PWAS; posterior probability of hypothesis 4 ≥ 75 % for Bayesian colocalization), and they were linked with lacunar stroke in confirmatory PWAS and independent MR. We also found that ICA1L is related to lacunar stroke at the brain transcriptome level.

CONCLUSIONS

Our present proteomic findings have identified ICA1L, CAND2, and ALDH2 as compelling genes that may give key hints for future functional research and possible therapeutic targets for lacunar stroke.

ALDH2 Hampers Immune Escape in Liver Hepatocellular Carcinoma through ROS/Nrf2-mediated Autophagy

Aldehyde dehydrogenase 2 (ALDH2) has been implicated in the progression of liver hepatocellular carcinoma (LIHC). The most important feature of LIHC is the immune escape process. This study sets to study the role of ALDH2 in regulating immune escape in LIHC. Bioinformatics analysis was applied to examine the expression of ALDH2 in LIHC and its impact on patients' survival. The effect of ALDH2 expression on malignant phenotype of LIHC cells was assessed by gain-of-function assays. RT-qPCR and Western blot were conducted to examine the expression of related factors, thus investigating the downstream mechanisms of ALDH2. ELISA assay was carried out to measure the level of oxidative stress in cells, and crystal violet staining was conducted to observe the killing effect of T cells on tumor cells. Finally, xenograft assay was carried out to verify the role of ALDH2 in vivo.ALDH2 was poorly expressed in LIHC, which predicted dismal prognoses for patients. ALDH2 inhibited the malignant aggressiveness of LIHC cells. ALDH2 blocked the activation of Nrf2 by suppressing reactive oxygen species (ROS) in LIHC, and Nrf2 significantly reversed the tumor-suppressing properties of ALDH2. Nrf2 hindered autophagy and led to immune escape of LIHC cells. Moreover, ALDH2 considerably suppressed the growth of xenografts, increased autophagy and promoted the accumulation of T cells in tumors. In contrast, Nrf2 drastically reversed the repressive effect of ALDH2 on tumor growth.ALDH2 impaired the ROS/Nrf2 axis to promote autophagy, thereby repressing immune escape in LIHC.