ALDH2 protects against stroke by clearing 4-HNE

Activation of mitochondrial aldehyde dehydrogenase 2 promotes hair growth in human hair follicles

INTRODUCTION

Hair loss is a common phenomenon associated with various environmental and genetic factors. Mitochondrial dysfunction-induced oxidative stress has been recognized as a crucial determinant of hair follicle (HF) biology. Aldehyde dehydrogenase 2 (ALDH2) mitigates oxidative stress by detoxifying acetaldehyde. This study investigated the potential role of ALDH2 modulation in HF function and hair growth promotion.

OBJECTIVES

To evaluate the effects of ALDH2 activation on oxidative stress in HFs and hair growth promotion.

METHODS

The modulatory role of ALDH2 on HFs was investigated using an ALDH2 activator. ALDH2 expression in human HFs was evaluated through in vitro immunofluorescence staining. Ex vivo HF organ culture was employed to assess hair shaft elongation, while the fluorescence probe 2',7'- dichlorodihydrofluorescein diacetate was utilized to detect reactive oxygen species (ROS). An in vivo mouse model was used to determine whether ALDH2 activation induces anagen.

RESULTS

During the anagen phase, ALDH2 showed significantly higher intensity than that in the telogen phase, and its expression was primarily localized along the outer layer of HFs. ALDH2 activation promoted anagen phase induction by reducing ROS levels and enhancing reactive aldehyde clearance, which indicated that ALDH2 functions as a ROS scavenger within HFs. Moreover, ALDH2 activation upregulated Akt/GSK 3β/β-catenin signaling in HFs.

CONCLUSIONS

Our findings highlight the hair growth promotion effects of ALDH2 activation in HFs and its potential as a promising therapeutic approach for promoting anagen induction.

Exploring Genetic Associations of 3 Types of Risk Factors With Ischemic Stroke: An Integrated Bioinformatics Study

BACKGROUND

Ischemic stroke (IS) is a major cause of disability and mortality worldwide. Increasing evidence suggests a strong association between blood pressure, blood glucose, circulating lipids, and IS. Nonetheless, the genetic association of these 3 risk factors with IS remains elusive.

METHODS

We screened genetic instruments related to blood pressure, blood glucose, and circulating lipids and paired them with IS genome-wide association study data to conduct Mendelian randomization analysis. Positive Mendelian randomization findings were then subjected to colocalization analysis. Subsequently, we utilized the Gene Expression Omnibus data set to perform differential expression analysis, aiming to identify differentially expressed associated genes. We determined the importance scores of these differentially expressed associated genes through 4 machine learning models and constructed a nomogram based on these findings.

RESULTS

The combined results of the Mendelian randomization analysis indicate that blood pressure (systolic blood pressure: odds ratio [OR], 1.02 [95% CI, 1.01-1.02]; diastolic blood pressure: OR, 1.03 [95% CI, 1.03-1.04]) and some circulating lipids (low-density lipoprotein cholesterol: OR, 1.06 [95% CI, 1.01-1.12]; apoA1: OR, 0.95 [95% CI, 0.92-0.98]; apoB: OR, 1.05 [95% CI, 1.01-1.09]; eicosapentaenoic acid: OR, 2.36 [95% CI, 1.41-3.96]) have causal relationships with the risk of IS onset. We identified 73 genes that are linked to blood pressure and circulating lipids in the context of IS, and 16 are differentially expressed associated genes. FURIN, MAN2A2, HDDC3, ALDH2, and TOMM40 were identified as feature genes for constructing the nomogram that provides a quantitative prediction of the risk of IS onset.

CONCLUSIONS

This study indicates that there are causal links between blood pressure, certain circulating lipids, and the development of IS. The potential mechanisms underlying these causal relationships involve the regulation of lipid metabolism, blood pressure, DNA repair and methylation, cell apoptosis and autophagy, immune inflammation, and neuronal protection, among others.

A mitochondrial-targeted activity-based sensing probe for ratiometric imaging of formaldehyde reveals key regulators of the mitochondrial one-carbon pool

Formaldehyde (FA) is both a highly reactive environmental genotoxin and an endogenously produced metabolite that functions as a signaling molecule and one-carbon (1C) store to regulate 1C metabolism and epigenetics in the cell. Owing to its signal-stress duality, cells have evolved multiple clearance mechanisms to maintain FA homeostasis, acting to avoid the established genotoxicity of FA while also redirecting FA-derived carbon units into the biosynthesis of essential nucleobases and amino acids. The highly compartmentalized nature of FA exposure, production, and regulation motivates the development of chemical tools that enable monitoring of transient FA fluxes with subcellular resolution. Here we report a mitochondrial-targeted, activity-based sensing probe for ratiometric FA detection, MitoRFAP-2, and apply this reagent to monitor endogenous mitochondrial sources and sinks of this 1C unit. We establish the utility of subcellular localization by showing that MitoRFAP-2 is sensitive enough to detect changes in mitochondrial FA pools with genetic and pharmacological modulation of enzymes involved in 1C and amino acid metabolism, including the pervasive, less active genetic mutant aldehyde dehydrogenase 2*2 (ALDH2*2), where previous, non-targeted versions of FA sensors are not. Finally, we used MitoRFAP-2 to comparatively profile basal levels of FA across a panel of breast cancer cell lines, finding that FA-dependent fluorescence correlates with expression levels of enzymes involved in 1C metabolism. By showcasing the ability of MitoRFAP-2 to identify new information on mitochondrial FA homeostasis, this work provides a starting point for the design of a broader range of chemical probes for detecting physiologically important aldehydes with subcellular resolution and a useful reagent for further studies of 1C biology.

Mitochondrial Aldehyde Dehydrogenase 2 (ALDH2) Protects against Binge Alcohol-Mediated Gut and Brain Injury

Mitochondrial aldehyde dehydrogenase-2 (ALDH2) metabolizes acetaldehyde to acetate. People with ALDH2 deficiency and Aldh2-knockout (KO) mice are more susceptible to alcohol-induced tissue damage. However, the underlying mechanisms behind ALDH2-related gut-associated brain damage remain unclear. Age-matched young female Aldh2-KO and C57BL/6J wild-type (WT) mice were gavaged with binge alcohol (4 g/kg/dose, three doses) or dextrose (control) at 12 h intervals. Tissues and sera were collected 1 h after the last ethanol dose and evaluated by histological and biochemical analyses of the gut and hippocampus and their extracts. For the mechanistic study, mouse neuroblast Neuro2A cells were exposed to ethanol with or without an Aldh2 inhibitor (Daidzin). Binge alcohol decreased intestinal tight/adherens junction proteins but increased oxidative stress-mediated post-translational modifications (PTMs) and enterocyte apoptosis, leading to elevated gut leakiness and endotoxemia in Aldh2-KO mice compared to corresponding WT mice. Alcohol-exposed Aldh2-KO mice also showed higher levels of hippocampal brain injury, oxidative stress-related PTMs, and neuronal apoptosis than the WT mice. Additionally, alcohol exposure reduced Neuro2A cell viability with elevated oxidative stress-related PTMs and apoptosis, all of which were exacerbated by Aldh2 inhibition. Our results show for the first time that ALDH2 plays a protective role in binge alcohol-induced brain injury partly through the gut-brain axis, suggesting that ALDH2 is a potential target for attenuating alcohol-induced tissue injury.

Ischemic Brain Injury: Involvement of Lipids in the Pathophysiology of Stroke and Therapeutic Strategies

Stroke is a devastating neurological disorder that is characterized by the sudden disruption of blood flow to the brain. Lipids are essential components of brain structure and function and play pivotal roles in stroke pathophysiology. Dysregulation of lipid signaling pathways modulates key cellular processes such as apoptosis, inflammation, and oxidative stress, exacerbating ischemic brain injury. In the present review, we summarize the roles of lipids in stroke pathology in different models (cell cultures, animal, and human studies). Additionally, the potential of lipids, especially polyunsaturated fatty acids, to promote neuroprotection and their use as biomarkers in stroke are discussed.

Surfeit Locus Protein 4 as a Novel Target for Therapeutic Intervention in Cerebral Ischemia-Reperfusion Injury

Surfeit locus protein 4 (SURF4) functions as a cargo receptor that is capable of transporting newly formed proteins from the lumen of the endoplasmic reticulum into vesicles and Golgi bodies. However, the role of SURF4 in the central nervous system remains unclear. The aim of this study is to investigate the role of SURF4 and its underlying mechanisms in cerebral ischemia/reperfusion (I/R) injury in rats, and whether it can be used effectively for novel therapeutic intervention. We also examined whether transcranial direct-current stimulation (tDCS) can exert a neuroprotective effect via SURF4-dependent signalling. Following cerebral I/R injury in rats, a significant increase was observed in the expression of SURF4. In both I/R injury and oxygen-glucose deprivation (OGD) insult, suppressing the expression of SURF4 demonstrated a neuroprotective effect, while overexpression of SURF4 resulted in increased neuronal death. We further showed that the levels of nerve growth factor precursor (proNGF), p75 neurotrophin receptor (p75NTR), sortilin, and PTEN were increased following cerebral I/R injury, and that SURF4 acted through the PTEN/proNGF signal pathway to regulate neuronal viability. We demonstrated that tDCS treatment reduced SURF4 expression and decreased the infarct volume after cerebral I/R injury. Together, this study indicates that SURF4 plays a critical role in ischemic neuronal injury and may serve as a molecular target for the development of therapeutic strategies in acute ischemic stroke.

Predictive value of serum MDA and 4-HNE levels on the occurrence of early neurological deterioration after intravenous thrombolysis with rt-PA IVT in patients with acute ischemic stroke

OBJECTIVE

This study investigated the predictive value of serum MDA and 4-HNE levels on early neurological deterioration (END) after recombinant tissue plasminogen activator (rt-PA) intravenous thrombolysis (IVT) in acute ischemic stroke (AIS) patients.

METHODS

This study analyzed 287 AIS patients with standard-dose rt-PA IVT. Clinical baseline and pathological data were recorded before rt-PA IVT, and neurologic deficit was assessed by NIHSS. AIS patients were classified into Non-END and END groups. Serum MDA and 4-HNE levels were determined by ELISA and their correlations with NIHSS scores were evaluated. AIS patients were allocated into groups with high and low MDA or 4-HNE expression, and post-IVT END incidence was compared. Independent risk indexes for post-IVT END and the predictive value of serum MDA+4-HNE levels on post-IVT END were assessed.

RESULTS

Serum MDA and 4-HNE were higher in AIS patients with post-IVT END. NIHSS score showed a positive correlation with serum MDA and 4-HNE levels. MDA levels were positively correlated with 4-HNE levels in AIS patients. END after IVT was increased in AIS patients with high MDA/4-HNE expression. FBG, lymphocyte percentage, PLR, NIHSS score, serum MDA, and 4-HNE levels were independent risk factors for END after IVT. The diagnostic efficacy of MDA+4-HNE in assessing post-IVT END in AIS patients (sensitivity 92.00 %, specificity 82.70 %) was higher than MDA or 4-HNE alone.

CONCLUSION

Serum MDA and 4-HNE levels were higher in AIS patients with post-IVT END than in those with non-END, and MDA+4-HNE possessed a higher predictive value for post-IVT END in AIS patients.

Mitochondrial aldehyde dehydrogenase-2 coordinates the hydrogen sulfide - AMPK axis to attenuate high glucose-induced pancreatic β-cell dysfunction by glutathione antioxidant system

Progression of β-cell loss in diabetes mellitus is significantly influenced by persistent hyperglycemia. At the cellular level, a number of signaling cascades affect the expression of apoptotic genes, ultimately resulting in β-cell failure; these cascades have not been elucidated. Mitochondrial aldehyde dehydrogenase-2 (ALDH2) plays a central role in the detoxification of reactive aldehydes generated from endogenous and exogenous sources and protects against mitochondrial deterioration in cells. Here we report that under diabetogenic conditions, ALDH2 is strongly inactivated in β-cells through CDK5-dependent glutathione antioxidant imbalance by glucose-6-phosphate dehydrogenase (G6PD) degradation. Intriguingly, CDK5 inhibition strengthens mitochondrial antioxidant defense through ALDH2 activation. Mitochondrial ALDH2 activation selectively preserves β-cells against high-glucose-induced dysfunction by activating AMPK and Hydrogen Sulfide (H2S) signaling. This is associated with the stabilization and enhancement of the activity of G6PD by SIRT2, a cytoplasmic NAD+-dependent deacetylase, and is thereby linked to an elevation in the GSH/GSSG ratio, which leads to the inhibition of mitochondrial dysfunction under high-glucose conditions. Furthermore, treatment with NaHS, an H2S donor, selectively preserves β-cell function by promoting ALDH2 activity, leading to the inhibition of lipid peroxidation by high-glucose concentrations. Collectively, our results provide the first direct evidence that ALDH2 activation enhances H2S-AMPK-G6PD signaling, leading to improved β-cell function and survival under high-glucose conditions via the glutathione redox balance.

Neuroprotective Effects of Aldehyde-Reducing Composition in an LPS-Induced Neuroinflammation Model of Parkinson's Disease

Parkinson's disease (PD) is a complex neurodegenerative disease in which neuroinflammation and oxidative stress interact to contribute to pathogenesis. This study investigates the in vivo neuroprotective effects of a patented yeast extract lysate in a lipopolysaccharide (LPS)-induced neuroinflammation model. The yeast extract lysate, named aldehyde-reducing composition (ARC), exhibited potent antioxidant and anti-aldehyde activities in vitro. Oral administration of ARC at 10 or 20 units/kg/day for 3 days prior to intraperitoneal injection of LPS (10 mg/kg) effectively preserved dopaminergic neurons in the substantia nigra (SN) and striatum by preventing LPS-induced cell death. ARC also normalized the activation of microglia and astrocytes in the SN, providing further evidence for its neuroprotective properties. In the liver, ARC downregulated the LPS-induced increase in inflammatory cytokines and reversed the LPS-induced decrease in antioxidant-related genes. These findings indicate that ARC exerts potent antioxidant, anti-aldehyde, and anti-inflammatory effects in vivo, suggesting its potential as a disease-modifying agent for the prevention and treatment of neuroinflammation-related diseases, including Parkinson's disease.

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.

tDCS Regulates ASBT-3-OxoLCA-PLOD2-PTEN Signaling Pathway to Confer Neuroprotection Following Rat Cerebral Ischemia-Reperfusion Injury

Humans exhibit a rich intestinal microbiome that contain high levels of bacteria capable of producing 3-oxo-lithocholic acid (3-oxoLCA) and other secondary bile acids (BAs). The molecular mechanism mediating the role of 3-oxoLCA in cerebral ischemia-reperfusion (I/R) injury remains unclear. We investigated the role of 3-oxoLCA in a rat cerebral I/R injury model. We found that the concentrations of 3-oxoLCA within the cerebrospinal fluid were increased following I/R. In the in vitro oxygen-glucose deprivation (OGD) model, the levels of intraneuronal 3-oxoLCA was elevated following OGD insult. We showed that the increase of membrane ASBT (apical sodium-dependent bile acid transporter) contributed to OGD-induced elevation of intraneuronal 3-oxoLCA. Increasing intraneuronal 3-oxoLCA promoted ischemia-induced neuronal death, whereas reducing 3-oxoLCA levels were neuroprotective. Our results revealed that PLOD2 (procollagen-lysine, 2-oxoglutarate 5-dioxygenases 2) functioned upstream of PTEN (the phosphatase and tensin homolog deleted on chromosome 10) and downstream of 3-oxoLCA to promote OGD-induced neuronal injury. We further demonstrated that direct-current stimulation (DCS) decreased the levels of intraneuronal 3-oxoLCA and membrane ASBT in OGD-insulted neurons, while bilateral transcranial DCS (tDCS) reduced brain infarct volume following I/R by inhibiting ASBT. Together, these data suggest that increased expression of ASBT promotes neuronal death via 3-oxoLCA-PLOD2-PTEN signaling pathway. Importantly, bilateral tDCS suppresses ischemia-induced increase of ASBT, thereby conferring neuroprotection after cerebral I/R injury.

The Chains of Ferroptosis Interact in the Whole Progression of Atherosclerosis

Atherosclerosis (AS), a category of cardiovascular disease (CVD) that can cause other more severe disabilities, increasingly jeopardizes human health. Owing to its imperceptible and chronic symptoms, it is hard to determine the pathogenesis and precise therapeutics for AS. A novel type of programmed cell death called ferroptosis was discovered in recent years that is distinctively different from other traditional cell death pathways in morphological and biochemical aspects. Characterized by iron overload, redox disequilibrium, and accumulation of lipid hydroperoxides (L-OOH), ferroptosis influences endothelial cells, vascular smooth muscle cells (VSMCs), and macrophages, as well as inflammation, partaking in the pathology of many cardiovascular diseases such as atherosclerosis, stroke, ischemia-reperfusion injury, and heart failure. The mechanisms behind ferroptosis are so sophisticated and interwoven that many molecules involved in this procedure are unknown. This review systematically depicts the initiation and modulation of ferroptosis and summarizes the contribution of ferroptosis to AS, which may open a feasible approach for target treatment in the alleviation of AS progression.

Association of Ferroptosis with Severity and Outcomes in Acute Ischemic Stroke Patients Undergoing Endovascular Thrombectomy: A Case-control Study

Ferroptosis, an iron-dependent form of cell death, is characterized by intracellular accumulation of iron and reactive oxygen species-induced lipid peroxidation. Animal experiments have shown the important roles of ferroptosis in ischemic stroke, but the evidence in human stroke is insufficient. This prospective study evaluated the associations between plasma ferroptosis biomarkers at hyperacute stage and long-term outcomes in patients with acute ischemic stroke undergoing endovascular thrombectomy (EVT). The plasma samples were collected immediately before and after EVT (T1 and T2) and at 24 h (T3) for the 126 stroke patients and once for the 50 stroke-free control subjects. Compared with controls, stroke patients had higher 4-hydroxynonenal (4-HNE) levels at T1 and T2 while lower homocysteine and soluble transferrin receptor (sTfR) levels at T3. In stroke patients, higher National Institutes of Health Stroke Scale scores at admission were correlated with higher 4-HNE and lower sTfR levels. Lower Alberta Stroke Program Early CT (ASPECT) scores and larger infarct core volumes on CT perfusion before EVT were correlated with higher 4-HNE and homocysteine levels. After adjusting for significant parameters, homocysteine levels at T2 were significantly associated with poor functional outcome and mortality at 3 months. In the receiver operating characteristic (ROC) models, adding homocysteine levels at T2 and hemoglobin levels to the reference model for predicting poor functional outcome significantly increased the area under the ROC curve. In summary, this study provides evidence that ferroptosis is associated with stroke severity and outcomes in patients with acute ischemic stroke undergoing EVT.

Implication of the cooking oil-peroxidation product "hydroxynonenal" for Alzheimer's disease

Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that reduces cell injuries via detoxification of lipid-peroxidation product, 4-hydroxy-2-nonenal (hydroxynonenal). It is generated exogenously via deep-frying of linoleic acid-rich cooking oils and/or endogenously via oxidation of fatty acids involved in biomembranes. Although its toxicity for human health is widely accepted, the underlying mechanism long remained unknown. In 1998, Yamashima et al. have formulated the "calpain-cathepsin hypothesis" as a molecular mechanism of ischemic neuronal death. Subsequently, they found that calpain cleaves Hsp70.1 which became vulnerable after the hydroxynonenal-induced carbonylation at the key site Arg469. Since it is the pivotal aberration that induces lysosomal membrane rupture, they suggested that neuronal death in Alzheimer's disease similarly occurs by chronic ischemia via the calpain-cathepsin cascade triggered by hydroxynonenal. For nearly three decades, amyloid β (Aβ) peptide was thought to be a root substance of Alzheimer's disease. However, because of both the insignificant correlations between Aβ depositions and occurrence of neuronal death or dementia, and the negative results of anti-Aβ medicines tested so far in the patients with Alzheimer's disease, the strength of the "amyloid cascade hypothesis" has been weakened. Recent works have suggested that hydroxynonenal is a mediator of programmed cell death not only in the brain, but also in the liver, pancreas, heart, etc. Increment of hydroxynonenal was considered an early event in the development of Alzheimer's disease. This review aims at suggesting ways out of the tunnel, focusing on the implication of hydroxynonenal in this disease. Herein, the mechanism of Alzheimer neuronal death is discussed by focusing on Hsp70.1 with a dual function as chaperone protein and lysosomal stabilizer. We suggest that Aβ is not a culprit of Alzheimer's disease, but merely a byproduct of autophagy/lysosomal failure resulting from hydroxynonenal-induced Hsp70.1 disorder. Enhancing ALDH2 activity to detoxify hydroxynonenal emerges as a promising strategy for preventing and treating Alzheimer's disease.

A whole-genome reference panel of 14,393 individuals for East Asian populations accelerates discovery of rare functional variants

Underrepresentation of non-European (EUR) populations hinders growth of global precision medicine. Resources such as imputation reference panels that match the study population are necessary to find low-frequency variants with substantial effects. We created a reference panel consisting of 14,393 whole-genome sequences including more than 11,000 Asian individuals. Genome-wide association studies were conducted using the reference panel and a population-specific genotype array of 72,298 subjects for eight phenotypes. This panel yields improved imputation accuracy of rare and low-frequency variants within East Asian populations compared with the largest reference panel. Thirty-nine previously unidentified associations were found, and more than half of the variants were East Asian specific. We discovered genes with rare protein-altering variants, including LTBP1 for height and GPR75 for body mass index, as well as putative regulatory mechanisms for rare noncoding variants with cell type-specific effects. We suggest that this dataset will add to the potential value of Asian precision medicine.

The role of aldehyde dehydrogenase 2 in cardiovascular disease

Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme involved in the detoxification of alcohol-derived acetaldehyde and endogenous aldehydes. The inactivating ALDH2 rs671 polymorphism, present in up to 8% of the global population and in up to 50% of the East Asian population, is associated with increased risk of cardiovascular conditions such as coronary artery disease, alcohol-induced cardiac dysfunction, pulmonary arterial hypertension, heart failure and drug-induced cardiotoxicity. Although numerous studies have attributed an accumulation of aldehydes (secondary to alcohol consumption, ischaemia or elevated oxidative stress) to an increased risk of cardiovascular disease (CVD), this accumulation alone does not explain the emerging protective role of ALDH2 rs671 against ageing-related cardiac dysfunction and the development of aortic aneurysm or dissection. ALDH2 can also modulate risk factors associated with atherosclerosis, such as cholesterol biosynthesis and HDL biogenesis in hepatocytes and foam cell formation and efferocytosis in macrophages, via non-enzymatic pathways. In this Review, we summarize the basic biology and the clinical relevance of the enzymatic and non-enzymatic, tissue-specific roles of ALDH2 in CVD, and discuss the future directions in the research and development of therapeutic strategies targeting ALDH2. A thorough understanding of the complex roles of ALDH2 in CVD will improve the diagnosis, management and prognosis of patients with CVD who harbour the ALDH2 rs671 polymorphism.

The Role of Potential Oxidative Biomarkers in the Prognosis of Acute Ischemic Stroke and the Exploration of Antioxidants as Possible Preventive and Treatment Options

Ischemic strokes occur when the blood supply to a part of the brain is interrupted or reduced due to arterial blockage, and it often leads to damage to brain cells or death. According to a myriad of experimental studies, oxidative stress is an important pathophysiological mechanism of ischemic stroke. In this narrative review, we aimed to identify how the alterations of oxidative stress biomarkers could suggest a severity-reflecting diagnosis of ischemic stroke and how these interactions may provide new molecular targets for neuroprotective therapies. We performed an eligibility criteria-based search on three main scientific databases. We found that patients with acute ischemic stroke are characterized by increased oxidative stress markers levels, such as the total antioxidant capacity, F2-isoprostanes, hydroxynonenal, total and perchloric acid oxygen radical absorbance capacity (ORACTOT and ORACPCA), malondialdehyde (MDA), myeloperoxidase, and urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine. Thus, acute ischemic stroke is causing significant oxidative stress and associated molecular and cellular damage. The assessment of these molecular markers could be useful in diagnosing ischemic stroke, finding its causes, predicting its severity and outcomes, reducing its impact on the cellular structures of the brain, and guiding preventive treatment towards antioxidant-based therapy as novel therapeutic alternatives.

Neuroprotection of NAD+ and NBP against ischemia/reperfusion brain injury is associated with restoration of sirtuin-regulated metabolic homeostasis

Background: Ischemic stroke seriously threatens human health because of high rates of morbidity, mortality and disability. This study compared the effects of nicotinamide adenine dinucleotide (NAD+) and butylphthalide (NBP) on in vitro and in vivo ischemic stroke models.

Methods: Transient middle cerebral artery occlusion/reperfusion (t-MCAO/R) model was established in mice, and the cultured primary cortical neurons were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). Cerebral infarct volume, neurobehavioral indices, antioxidant activity, ATP level and lactic acid content were determined. The neuroprotective effects of NAD+ or NBP were compared using sirtuin inhibitor niacinamide (NAM).

Results: Intraperitoneal injection of NBP within 4 h or intravenous injection of NAD+ within 1 h after t-MCAO/R significantly reduced the volume of infarcts, cerebral edema, and neurological deficits. Administration of NAD+ and NBP immediately after t-MCAO/R in mice showed similar neuroprotection against acute and long-term ischemic injury. Both NAD+ and NBP significantly inhibited the accumulation of MDA and H2O2 and reduced oxidative stress. NAD+ was superior to NBP in inhibiting lipid oxidation and DNA damage. Furthermore, although both NAD+ and NBP improved the morphology of mitochondrial damage induced by ischemia/reperfusion, NAD+ more effectively reversed the decrease of ATP and increase of lactic acid after ischemia/reperfusion compared with NBP. NAD+ but not NBP treatment significantly upregulated SIRT3 in the brain, but the sirtuin inhibitor NAM could abolish the protective effect of NAD+ and NBP by inhibiting SIRT1 or SIRT3.

Conclusions: These results confirmed the protective effects of NAD+ and NBP on cerebral ischemic injury. NBP and NAD+ showed similar antioxidant effects, while NAD+ had better ability in restoring energy metabolism, possibly through upregulating the activity of SIRT1 and SIRT3. The protection provided by NBP against cerebral ischemia/reperfusion may be achieved through SIRT1.

Exercise pretreatment alleviates neuroinflammation and oxidative stress by TFEB-mediated autophagic flux in mice with ischemic stroke

BACKGROUND

Neuroinflammation and oxidative stress are important pathological mechanisms underlying cerebral ischemic stroke. Increasing evidence suggests that regulation autophagy in ischemic stroke may improve neurological functions. In this study, we aimed to explore whether exercise pretreatment attenuates neuroinflammation and oxidative stress in ischemic stroke by improving autophagic flux.

METHODS

2,3,5-Triphenyltetrazolium chloride staining was used to determine the infarction volume, and modified Neurological Severity Scores and rotarod test were used to evaluate neurological functions after ischemic stroke. The levels of oxidative stress, neuroinflammation, neuronal apoptosis and degradation, autophagic flux, and signaling pathway proteins were determined using immunofluorescence, dihydroethidium, TUNEL, and Fluoro-Jade B staining, western blotting, and co-immunoprecipitation.

RESULTS

Our results showed that, in middle cerebral artery occlusion (MCAO) mice, exercise pretreatment improved neurological functions and defective autophagy, and reduced neuroinflammation and oxidative stress. Mechanistically, after using chloroquine, impaired autophagy abolished the neuroprotection of exercise pretreatment. And transcription factor EB (TFEB) activation mediated by exercise pretreatment contributes to improving autophagic flux after MCAO. Furthermore, we showed that TFEB activation mediated by exercise pretreatment in MCAO was regulated by the AMPK-mTOR and AMPK-FOXO3a-SKP2-CARM1 signaling pathways.

CONCLUSIONS

Exercise pretreatment has the potential to improve the prognosis of ischemic stroke patients, and it can exert neuroprotective effects in ischemic stroke by inhibiting neuroinflammation and oxidative stress, which might be due to the TFEB-mediated autophagic flux. And targeting autophagic flux may be promising strategies for the treatment of ischemic stroke.

CHAC1 as a Novel Contributor of Ferroptosis in Retinal Pigment Epithelial Cells with Oxidative Damage

Age-related macular degeneration (AMD) is the leading cause of irreversible visual loss in the elderly population. With aging and the accumulated effects of environmental stress, retinal pigment epithelial (RPE) cells are particularly susceptible to oxidative damage, which can lead to retinal degeneration. However, the underlying molecular mechanisms of how RPE responds and progresses under oxidative damage are still largely unknown. Here, we reveal that exogenous oxidative stress led to ferroptosis characterized by Fe2+ accumulation and lipid peroxidation in RPE cells. Glutathione specific gamma-glutamylcyclotransferase 1 (Chac1), as a component of the unfolded protein response (UPR) pathway, plays a pivotal role in oxidative-stress-induced cell ferroptosis via the regulation of glutathione depletion. These results indicate the biological significance of Chac1 as a novel contributor of oxidative-stress-induced ferroptosis in RPE, suggesting its potential role in AMD.

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.

Involvement of baroreflex deficiency in the age-related loss of estrogen efficacy against cerebral ischemia

For post-menopausal women, stroke is complicated by the variable effects of estrogen therapy and the age-related therapeutic consequences involved. Estrogen therapy has been shown to have an age-dimorphic effect, which is neuroprotective in young females, but non-neuroprotective, even neurotoxic in acyclic females. We hypothesized that arterial baroreflex (ABR) and its downstream acetylcholine-α7 nicotinic acetylcholine receptor (α7nAChR) anti-inflammatory pathways are involved in estrogen efficacy toward cerebral ischemic damage. Our data showed that estrogen supplements contributed to ABR improvement and neuroprotection in adult, not aged, ovariectomized (OVX) rats. In adult rats, OVX-induced estrogen deficiency aggravated middle cerebral artery occlusion (MCAO), which induced brain infarction and reduced ABR function, with decreased α7nAChR expression of the brain and exaggerated inflammation following MCAO; these effects were significantly prevented by supplementation with estrogen. ABR impairment by sinoaortic denervation partly attenuated the estrogen effect on baroreflex sensitivity (BRS) and ischemic damage in adult rats, as well as α7nAChR expression and inflammatory response. These data suggested that ABR and acetylcholine-α7nAChR anti-inflammatory pathways are involved in the neuroprotection of estrogen in adult OVX rats. In contrast, aged rats exhibited more severe ischemic damage and inflammatory response than adult rats, as well as poorer baroreflex function and lower α7nAChR expression. Estrogen supplements did not improve BRS or confer neuroprotection in aged rats without affecting brain α7nAChR and post-ischemic inflammation. Most importantly, ketanserin restored ABR function and significantly postponed the onset of stroke in aged female strokeprone spontaneously hypertensive rats, whereas estrogen treatment failed to delay the development of stroke. Our findings reveal that estrogen is protective against ischemic stroke (IS) in adult female rats and that ABR played a role in this beneficial action. Dysfunction of ABR and unresponsiveness to estrogen in aged female rats may contribute to a reduced estrogen efficacy against cerebral ischemia.

Aldehyde Dehydrogenase 2 Ameliorates LPS-Induced Acute Kidney Injury through Detoxification of 4-HNE and Suppression of the MAPK Pathway

Lipopolysaccharide (LPS)-induced septic acute kidney injury (AKI) is determined as a devastating organ dysfunction elicited by an inappropriate response to infection with high morbidity and mortality rates. Previous evidence has illustrated an indispensable role of mitochondrial aldehyde dehydrogenase 2 (ALDH2) in the pathogenesis of sepsis-induced multiorgan abnormalities. Specifically, this study investigated the potential role of ALDH2 in sepsis-induced AKI. After LPS administration, we observed a significant decline in renal function, increased inflammatory cytokines, oxidative stress, 4-hydroxy-2-nonenal (4-HNE) accumulation, and apoptosis via MAPK activation in ALDH2^-/- mice; in contrast, pretreatment with Alda-1 (an ALDH2 activator) alleviated the LPS-induced dysfunctions in mice. Moreover, in vitro analysis revealed that ALDH2 overexpression in mouse tubular epithelial cells (mTECs) improved the inflammatory response, oxidative stress, 4-HNE accumulation, and apoptosis via MAPK inhibition, whereas ALDH2 knockdown in mTECs aggravated these parameters via MAPK activation. Therefore, ALDH2 may protect against LPS-induced septic AKI by suppressing 4-HNE/MAPK pathway.

Electrophilic Aldehyde 4-Hydroxy-2-Nonenal Mediated Signaling and Mitochondrial Dysfunction

Reactive oxygen species (ROS), a by-product of aerobic life, are highly reactive molecules with unpaired electrons. The excess of ROS leads to oxidative stress, instigating the peroxidation of polyunsaturated fatty acids (PUFA) in the lipid membrane through a free radical chain reaction and the formation of the most bioactive aldehyde, known as 4-hydroxynonenal (4-HNE). 4-HNE functions as a signaling molecule and toxic product and acts mainly by forming covalent adducts with nucleophilic functional groups in proteins, nucleic acids, and lipids. The mitochondria have been implicated as a site for 4-HNE generation and adduction. Several studies clarified how 4-HNE affects the mitochondria's functions, including bioenergetics, calcium homeostasis, and mitochondrial dynamics. Our research group has shown that 4-HNE activates mitochondria apoptosis-inducing factor (AIFM2) translocation and facilitates apoptosis in mice and human heart tissue during anti-cancer treatment. Recently, we demonstrated that a deficiency of SOD2 in the conditional-specific cardiac knockout mouse increases ROS, and subsequent production of 4-HNE inside mitochondria leads to the adduction of several mitochondrial respiratory chain complex proteins. Moreover, we highlighted the physiological functions of HNE and discussed their relevance in human pathophysiology and current discoveries concerning 4-HNE effects on mitochondria.

Silencing of YTHDF1 Attenuates Cerebral Stroke by Inducing PTEN Degradation and Activating the PTEN/AKT/mTOR Pathway

N6-methyladenosine (m6A) methylation regulates pathological processes of cerebral stroke, which can lead to disability and death. Herein, we explored the role of a m6A "reader" YTHDF1 in stroke. MCAO (middle cerebral artery occlusion) rat model and hypoxia/reoxygenation (H/R)-induced neurocytes cell model were established. TTC staining assay assessed the infarction area and TUNEL assay analyzed apoptosis. Neurological score was analyzed to evaluate the brain function. Cell counting kit-8, LDH release, and flow cytometry assessed cellular proliferation, cell death, and cell apoptosis in vitro. The expression of YTHDF1, PTEN, and the factors in the PI3K/AKT/mTOR pathway was measured using western blot. The interaction between YTHDF1 and PTEN was confirmed luciferase assay and RNA immunoprecipitation assay. The results indicated that YTHDF1 was upregulated in the brain tissues of MCAO mice and H/R-treated cells. Knockdown of YTHDF1 inhibited the infarct area, neuron damage, and apoptosis. Additionally, YTHDF1 depletion promoted viability and inhibited apoptosis of H/R-treated cells. Moreover, YTHDF1 inactivated the PI3K/AKT/mTOR pathway. Mechanistically, YTHDF1 binds to PTEN to increase PTEN mRNA stability. Overexpressing PTEN rescued the effects of YTHDF1 depletion on cell viability and apoptosis. In conclusion, silencing of YTHDF1 decelerated the progression of cerebral stroke through promoting PTEN degradation and activating the PTEN/AKT/mTOR pathway, suggesting that YTHDF1 has the potential to be a therapeutic target for stroke.

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.

γ-Glutamylcysteine Exerts Neuroprotection Effects against Cerebral Ischemia/Reperfusion Injury through Inhibiting Lipid Peroxidation and Ferroptosis

Ferroptosis is a non-apoptotic form of cell death driven by iron-dependent lipid peroxidation. Recent evidence indicates that inhibiting ferroptosis could alleviate cerebral ischemia/reperfusion (CIR) injury. γ-glutamylcysteine (γ-GC), an intermediate of glutathione (GSH) synthesis, can upregulate GSH in brains. GSH is the co-factor of glutathione peroxidase 4 (GPX4), which is the negative regulator of ferroptosis. In this study, we explored the effect of γ-GC on CIR-induced neuronal ferroptosis and brain injury. We found that γ-GC significantly reduced the volume of cerebral infarction, decreased the loss of neurons and alleviated neurological dysfunction induced by CIR in rats. Further observation showed that γ-GC inhibited the CIR-caused rupture of the neuronal mitochondrial outer membrane and the disappearance of cristae, and decreased Fe2+ deposition and lipid peroxidation in rat cerebral cortices. Meanwhile, γ-GC altered the expression of some ferroptosis-related proteins in rat brains. Mechanistically, γ-GC increased the expression of GSH synthetase (GSS) for GSH synthesis via protein kinase C (PKC)ε-mediated activation of nuclear factor erythroid 2-related factor (Nrf2). Our findings suggest that γ-GC not only serves as a raw material but also increases the GSS expression for GSH synthesis against CIR-induced lipid peroxidation and ferroptosis. Our study strongly suggests that γ-GC has potential for treating CIR injury.

Harmful Impact of Tobacco Smoking and Alcohol Consumption on the Atrial Myocardium

Tobacco smoking and alcohol consumption are widespread exposures that are legal and socially accepted in many societies. Both have been widely recognized as important risk factors for diseases in all vital organ systems including cardiovascular diseases, and with clinical manifestations that are associated with atrial dysfunction, so-called atrial cardiomyopathy, especially atrial fibrillation and stroke. The pathogenesis of atrial cardiomyopathy, atrial fibrillation, and stroke in context with smoking and alcohol consumption is complex and multifactorial, involving pathophysiological mechanisms, environmental, and societal aspects. This narrative review summarizes the current literature regarding alterations in the atrial myocardium that is associated with smoking and alcohol.

Association of functional variant of aldehyde dehydrogenase 2 with acute myocardial infarction of Chinese patients

BACKGROUND

The variant of ALDH2 was thought to be associated with Acute Myocardial Infarction (AMI) due to the consumption of alcohol. This study focused on how ALDH2 variant acts as an independent risk factor for AMI, regardless of alcohol consumption.

METHODS AND RESULTS

We used the case-control INTERHEART-China study which took place at 25 centres in 17 cities in mainland China. Cases were patients with AMI and matched by age, sex, and site to controls. Information about alcohol consumption and genotype were collected. We divided cases and controls by alcohol consumption: alcohol intake group and no alcohol intake group. Then, calculated the Odd Ratio (OR) value with confidence interval (CI) at 95% level to find the association between ALDH2 variant and AMI. Results were then adjusted by sex, age, BMI, and other common risk factors of AMI. The study involves a total of 2660 controls and 2322 AMI patients. The no drink intake group showed that there was a correlation between the ALDH2 variant and AMI (OR = 1.236, 95% CI = 1.090-1.401, p = 0.00092). After adjustment of different risk factors this association remained (OR = 1.247, 95% CI = 1.099-1.415, p = 0.00062). Similar results were also obtained from the no alcohol intake group (OR = 1.196, 95% CI = 0.993-1.440, p = 0.05963), however, due to the limited sample size, the result was not significant enough statistically.

CONCLUSION

From our results, ALDH2 variant is associated with the risk of AMI even in population that has no alcohol consumption. This suggests that ALDH2 variant may act as an independent risk factor for AMI.

Identifying causal genes for stroke via integrating the proteome and transcriptome from brain and blood

Background

Genome-wide association studies (GWAS) have revealed numerous loci associated with stroke. However, the underlying mechanisms at these loci in the pathogenesis of stroke and effective stroke drug targets are elusive. Therefore, we aimed to identify causal genes in the pathogenesis of stroke and its subtypes.

Methods

Utilizing multidimensional high-throughput data generated, we integrated proteome-wide association study (PWAS), transcriptome-wide association study (TWAS), Mendelian randomization (MR), and Bayesian colocalization analysis to prioritize genes that contribute to stroke and its subtypes risk via affecting their expression and protein abundance in brain and blood.

Results

Our integrative analysis revealed that ICA1L was associated with small-vessel stroke (SVS), according to robust evidence at both protein and transcriptional levels based on brain-derived data. We also identified NBEAL1 that was causally related to SVS via its cis-regulated brain expression level. In blood, we identified 5 genes (MMP12, SCARF1, ABO, F11, and CKAP2) that had causal relationships with stroke and stroke subtypes.

Conclusions

Together, via using an integrative analysis to deal with multidimensional data, we prioritized causal genes in the pathogenesis of SVS, which offered hints for future biological and therapeutic studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03377-9.

Association Study and Meta-Analysis of Polymorphisms and Blood mRNA Expression of the ALDH2 Gene in Patients with Alzheimer’s Disease

Background:

Late-onset Alzheimer’s disease (LOAD) is a complex disease in which neuroinflammation plays an important pathophysiological role, and exposure to neurotoxic substrates such as aldehydes may contribute. Blood mRNA expression levels of neuroinflammation-related genes appear to be potential biological markers of LOAD. A relationship between ALDH2 and LOAD has been suggested.

Objective:

Our objective was to examine blood ALDH2 expression in Japanese LOAD patients, conduct a genetic association study, and add new studies to an extended meta-analysis of the Asian population.

Methods:

A blood expression study (45 AD subjects, 54 controls) in which total RNA was isolated from whole peripheral blood samples and ALDH2 expression measured was conducted. In addition, a genetic association study (271 AD subjects, 492 controls) using genomic DNA from whole peripheral blood samples was conducted. Finally, a meta-analysis examined the relationship between ALDH2^*2 frequency and the risk of LOAD.

Results:

ALDH2 mRNA expression was significantly higher in LOAD than in controls, and also higher in men with LOAD than in women with LOAD (p = 0.043). The genotypes in the two classified groups and the allele frequency were significantly different between AD and control subjects. The meta-analysis showed a significant difference in the ALDH2^*2 allele, with an increased AD risk (OR = 1.38; 95% CI = 1.02–1.85; p = 0.0348, I² = 81.1%).

Conclusion:

There was a significant increase in blood ALDH2 expression, and a genetic association with ALDH2^*2 in LOAD. ALDH2 may have significant roles in the pathogenesis of LOAD in the Asian population.

The ALDH2 rs671 polymorphism is associated with athletic status and muscle strength in a Japanese population

Aldehyde dehydrogenase 2 (ALDH2) catalyses aldehyde species, including alcohol metabolites, mainly in the liver. We recently observed that ALDH2 is also expressed in skeletal muscle mitochondria; thus, we hypothesize that rs671 polymorphism-promoted functional loss of ALDH2 may induce deleterious effects in human skeletal muscle. We aimed to clarify the association of the ALDH2 rs671 polymorphism with muscle phenotypes and athletic capacity in a large Japanese cohort. A total of 3,055 subjects, comprising 1,714 athletes and 1,341 healthy control subjects (non-athletes), participated in this study. Non-athletes completed a questionnaire regarding their exercise habits, and were subjected to grip strength, 30-s chair stand, and 8-ft walking tests to assess muscle function. The ALDH2 GG, GA, and AA genotypes were detected at a frequency of 56%, 37%, and 7% among athletes, and of 54%, 37%, and 9% among non-athletes, respectively. The minor allele frequency was 25% in athletes and 28% in controls. Notably, ALDH2 genotype frequencies differed significantly between athletes and non-athletes (genotype: p = 0.048, allele: p = 0.021), with the AA genotype occurring at a significantly lower frequency among mixed-event athletes compared to non-athletes (p = 0.010). Furthermore, non-athletes who harboured GG and GA genotypes exhibited better muscle strength than those who carried the AA genotype (after adjustments for age, sex, body mass index, and exercise habits). The AA genotype and A allele of the ALDH2 rs671 polymorphism were associated with a reduced athletic capacity and poorer muscle phenotypes in the analysed Japanese cohort; thus, impaired ALDH2 activity may attenuate muscle function.

Positive selection acts on regulatory genetic variants in populations of European ancestry that affect ALDH2 gene expression

ALDH2 is a key enzyme in alcohol metabolism that protects cells from acetaldehyde toxicity. Using iHS, iSAFE and FST statistics, we identified regulatory acting variants affecting ALDH2 gene expression under positive selection in populations of European ancestry. Several SNPs (rs3184504, rs4766578, rs10774625, rs597808, rs653178, rs847892, rs2013002) that function as eQTLs for ALDH2 in various tissues showed evidence of strong positive selection. Very large pairwise FST values indicated high genetic differentiation at these loci between populations of European ancestry and populations of other global ancestries. Estimating the timing of positive selection on the beneficial alleles suggests that these variants were recently adapted approximately 3000-3700 years ago. The derived beneficial alleles are in complete linkage disequilibrium with the derived ALDH2 promoter variant rs886205, which is associated with higher transcriptional activity. The SNPs rs4766578 and rs847892 are located in binding sequences for the transcription factor HNF4A, which is an important regulatory element of ALDH2 gene expression. In contrast to the missense variant ALDH2 rs671 (ALDH2*2), which is common only in East Asian populations and is associated with greatly reduced enzyme activity and alcohol intolerance, the beneficial alleles of the regulatory variants identified in this study are associated with increased expression of ALDH2. This suggests adaptation of Europeans to higher alcohol consumption.

Oxidative stress and regeneration

Regeneration is the process of replacing/restoring a damaged cell/tissue/organ to its full function and is limited respecting complexity of specific organ structures and the level of differentiation of the cells. Unlike physiological cell turnover, this tissue replacement form is activated upon pathological stimuli such as injury and/or disease that usually involves inflammatory response. To which extent will tissue repair itself depends on many factors and involves different mechanisms. Oxidative stress is one of them, either acute, as in case of traumatic brin injury or chronic, as in case of neurodegeneration, oxidative stress within brain involves lipid peroxidation, which generates reactive aldehydes, such as 4-hydroxynonenal (4-HNE). While 4-HNE is certainly neurotoxic and causes disruption of the blood brain barrier in case of severe injuries, it is also physiologically produced by glial cells, especially astrocytes, but its physiological roles within CNS are not understood. Because 4-HNE can regulate the response of the other cells in the body to stress, enhance their antioxidant capacities, proliferation and differentiation, we could assume that it may also have some beneficial role for neuroregeneration. Therefore, future studies on the relevance of 4-HNE for the interaction between neuronal cells, notably stem cells and reactive astrocytes might reveal novel options to better monitor and treat consequences or brain injuries, neurodegeneration and regeneration.

Aldehyde Dehydrogenase 2 as a Therapeutic Target in Oxidative Stress-Related Diseases: Post-Translational Modifications Deserve More Attention

Aldehyde dehydrogenase 2 (ALDH2) has both dehydrogenase and esterase activity; its dehydrogenase activity is closely related to the metabolism of aldehydes produced under oxidative stress (OS). In this review, we recapitulate the enzyme activity of ALDH2 in combination with its protein structure, summarize and show the main mechanisms of ALDH2 participating in metabolism of aldehydes in vivo as comprehensively as possible; we also integrate the key regulatory mechanisms of ALDH2 participating in a variety of physiological and pathological processes related to OS, including tissue and organ fibrosis, apoptosis, aging, and nerve injury-related diseases. On this basis, the regulatory effects and application prospects of activators, inhibitors, and protein post-translational modifications (PTMs, such as phosphorylation, acetylation, S-nitrosylation, nitration, ubiquitination, and glycosylation) on ALDH2 are discussed and prospected. Herein, we aimed to lay a foundation for further research into the mechanism of ALDH2 in oxidative stress-related disease and provide a basis for better use of the ALDH2 function in research and the clinic.

High-Fat Diet Augments the Effect of Alcohol on Skeletal Muscle Mitochondrial Dysfunction in Mice

Previous studies have shown that chronic heavy alcohol consumption and consumption of a high-fat (HF) diet can independently contribute to skeletal muscle oxidative stress and mitochondrial dysfunction, yet the concurrent effect of these risk factors remains unclear. We aimed to assess the effect of alcohol and different dietary compositions on mitochondrial activity and oxidative stress markers. Male and female mice were randomized to an alcohol (EtOH)-free HF diet, a HF + EtOH diet, or a low-Fat (LF) + EtOH diet for 6 weeks. At the end of the study, electron transport chain complex activity and expression as well as antioxidant activity and expression, were measured in skeletal muscles. Complex I and III activity were diminished in muscles of mice fed a HF + EtOH diet relative to the EtOH-free HF diet. Lipid peroxidation was elevated, and antioxidant activity was diminished, in muscles of mice fed a HF + EtOH diet as well. Consumption of a HF diet may exacerbate the negative effects of alcohol on skeletal muscle mitochondrial health and oxidative stress.

Critical role of mitochondrial aldehyde dehydrogenase 2 in acrolein sequestering in rat spinal cord injury

Lipid peroxidation-derived aldehydes, such as acrolein, the most reactive aldehyde, have emerged as key culprits in sustaining post-spinal cord injury (SCI) secondary pathologies leading to functional loss. Strong evidence suggests that mitochondrial aldehyde dehydrogenase-2 (ALDH2), a key oxidoreductase and powerful endogenous anti-aldehyde machinery, is likely important for protecting neurons from aldehydes-mediated degeneration. Using a rat model of spinal cord contusion injury and recently discovered ALDH2 activator (Alda-1), we planned to validate the aldehyde-clearing and neuroprotective role of ALDH2. Over an acute 2 day period post injury, we found that ALDH2 expression was significantly lowered post-SCI, but not so in rats given Alda-1. This lower enzymatic expression may be linked to heightened acrolein-ALDH2 adduction, which was revealed in co-immunoprecipitation experiments. We have also found that administration of Alda-1 to SCI rats significantly lowered acrolein in the spinal cord, and reduced cyst pathology. In addition, Alda-1 treatment also resulted in significant improvement of motor function and attenuated post-SCI mechanical hypersensitivity up to 28 days post-SCI. Finally, ALDH2 was found to play a critical role in in vitro protection of PC12 cells from acrolein exposure. It is expected that the outcome of this study will broaden and enhance anti-aldehyde strategies in combating post-SCI neurodegeneration and potentially bring treatment to millions of SCI victims. All animal work was approved by Purdue Animal Care and Use Committee (approval No. 1111000095) on January 1, 2021.

Prospective study: Aldehyde dehydrogenase 2 gene is associated with cardio-cerebrovascular complications in type 2 diabetes patients

AIMS/INTRODUCTION

Most studies have shown that aldehyde dehydrogenase 2 (ALDH2) mutations were associated with cardio-cerebrovascular complications of diabetes based on cross-sectional investigations, but few studies based on cohorts were carried out. The aim of this study was to explore the correlation between the ALDH2 gene and the occurrence of and death from cardio-cerebrovascular complications in type 2 diabetes patients through a prospective cohort study.

MATERIALS AND METHODS

According to a community-based and disease-based prospective cohort study design, a baseline cohort of 10,339 persons with type 2 diabetes was established in 2016, and the occurrence of and death from cardio-cerebrovascular complications were followed up until December 2018. A total of 2,500 diabetes patients without cardio-cerebrovascular complications were randomly selected from the baseline cohort to detect the rs671 polymorphism of the ALDH2 gene. Cox regression analysis was carried out on the effect of different ALDH2 rs671 single-nucleotide polymorphisms on the risk and survival time of cardio-cerebrovascular complications among diabetes patients.

RESULTS

There were 215 cardio-cerebrovascular complications, including 10 deaths, that occurred in the 2,500 diabetes patients during the follow-up period. Cox regression analysis showed that rs671 GA/AA genotype, sex (male), poor control of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, blood pressure and glycated were risk factors, whereas drinking alcohol was a protective factor for cardio-cerebrovascular complications (P < 0.05). After adjusting for age and sex, the risk of the rs671 GA/AA genotype was 1.314-fold (95% confidence interval 1.000-1.727) that of the GG genotype.

CONCLUSION

The G-A mutation of ALDH2 rs671 is a risk factor for the occurrence of and death from cardio-cerebrovascular complications in type 2 diabetes patients. Further studies with larger cohorts and longer follow up will be necessary to reveal a consensus.

Deregulated Protein Kinases: Friend and Foe in Ischemic Stroke

Ischemic stroke is the third leading cause of mortality worldwide, but its medical management is still limited to the use of thrombolytics as a lifesaving option. Multiple molecular deregulations of the protein kinase family occur during the period of ischemia/reperfusion. However, experimental studies have shown that alterations in the expression of essential protein kinases and their pharmacological modulation can modify the neuropathological milieu and hasten neurophysiological recovery. This review highlights the role of key protein kinase members and their implications in the evolution of stroke pathophysiology. Activation of ROCK-, MAPK-, and GSK-3β-mediated pathways following neuronal ischemia/reperfusion injury in experimental conditions aggravate the neuropathology and delays recovery. Targeting ROCK, MAPK, and GSK-3β will potentially enhance myelin regeneration, improve blood-brain barrier (BBB) function, and suppress inflammation, which ameliorates neuronal survival. Conversely, protein kinases such as PKA, Akt, PKCα, PKCε, Trk, and PERK salvage neurons post-ischemia by mechanisms including enhanced toxin metabolism, restoring BBB integrity, neurotrophic effects, and apoptosis suppression. Certain protein kinases such as ERK1/2, JNK, and AMPK have favourable and unfavourable effects in salvaging ischemia-injured neurons. Targeting multiple protein kinase-mediated pathways simultaneously may improve neuronal recovery post-ischemia.

Impact of mitochondrial aldehyde dehydrogenase 2 on cognitive impairment in the AD model mouse

Alzheimer's disease (AD) is one of the major life-threatening diseases for the elderly because neither pathogenesis nor effective treatment is available. Mitochondrial aldehyde dehydrogenase 2 (ALDH2) has been shown to reduce the cell-damaging aldehydes in response to reactive oxygen species (ROS). However, whether it plays a role in AD remains elusive. In the present study, we found that ALDH2 overexpression significantly improved the cognitive function of the AD mouse. Behavioral analyses of ALDH2-overexpressing APP/PS1 AD mice showed that the learning and cognitive abilities were significantly higher in these mice than in the control group APP/PS1 mice. Further open-field behavior experiments showed the same results. At the cellular level, ALDH2 protects nerve cells. HT22 cells were challenged with Aβ to establish an AD cell model, in the presence or absence of the ALDH2 activator Alda-1 and ALDH2 inhibitor Daidzin. Incubation with 50 μM Aβ for 24 h significantly reduced HT22 cell survival and cell viability, the effects of which were attenuated by the ALDH2 activator Alda-1 (50 μM). Aβ challenge promoted apoptosis and upregulated caspase3 level but suppressed Bcl-2 level, and the upregulated caspase3 level was reversed by the ALDH-2 agonist Alda-1. Aβ-induced clonal ball abnormal was reversed by Alda-1. Aβ altered the mitochondria geometry evidenced by vacuolar degeneration and membrane rupture, whereas Alda-1 changed the Aβ-induced mitochondria geometry anomalies. Moreover, superoxide anion and toxic 4-hydroxy-nonanal (4-HNE) and ROS increased by Aβ challenge were reversed by Alda-1. Meanwhile, Aβ-induced ATP reduction was reversed by Alda-1. Taken together, ALDH2 overexpression significantly improves the cognitive function of the AD mice. Furthermore, our results suggested that ALDH2 protects against Aβ hippocampal neuronal toxicity possibly through alleviating toxic aldehydes and ROS, as well as increasing ATP production to preserve mitochondrial integrity and reduce neuronal apoptosis.

SETD3 Downregulation Mediates PTEN Upregulation-Induced Ischemic Neuronal Death Through Suppression of Actin Polymerization and Mitochondrial Function

SET domain protein 3 (SETD3) is an actin-specific methyltransferase, a rare post-translational modification with limited known biological functions. Till now, the function of SETD3 in cerebral ischemia-reperfusion (I/R)-induced injury remains unknown. Here, we show that the protein level of SETD3 is decreased in rat neurons after cerebral I/R injury. SETD3 promotes neuronal survival after both glucose and oxygen deprivation/reoxygenation (OGD/R) and cerebral I/R injury, and knockdown of SETD3 increases OGD/R-induced neuronal death. We further show that OGD/R-induced downregulation of SETD3 leads to the decrease of cellular ATP level, the reduction of mitochondrial electric potential and the increase of ROS production, thereby promoting mitochondrial dysfunction. We found that SETD3 reduction-induced mitochondrial dysfunction is mediated by the suppression of actin polymerization after OGD/R. Furthermore, we demonstrate that I/R-induced upregulation of PTEN leads to the downregulation of SETD3, and suppressing PTEN protects against ischemic neuronal death through downregulation of SETD3 and enhancement of actin polymerization. Together, this study provides the first evidence suggesting that I/R-induced downregulation of SETD3 mediates PTEN upregulation-induced ischemic neuronal death through downregulation of SETD3 and subsequent suppression of actin polymerization. Thus, upregulating SETD3 is a potential approach for the development of ischemic stroke therapy.

Synergistic Effects of Aldehyde Dehydrogenase 2 Polymorphisms and Alcohol Consumption on Cognitive Impairment after Ischemic Stroke in Han Chinese

Aldehyde dehydrogenase 2 (ALDH2) polymorphisms are related to both stroke risk and alcohol consumption. However, the influence of ALDH2 polymorphisms and alcohol consumption on cognitive impairment after ischemic stroke remains unknown, as do the possible mechanisms. We enrolled 180 Han Chinese ischemic stroke patients from four community health centers in Bengbu, China. Cognitive function was assessed using the Montreal Cognitive Assessment (MoCA), and two different MoCA cutoff scores were used to define cognitive impairment in ischemic stroke patients. The ALDH2 genotypes were determined using polymerase chain reaction and direct sequencing. To assess the associations of ALDH2 polymorphisms and alcohol consumption with cognitive impairment after ischemic stroke, we performed binary logistic regression analysis with odds ratios. We revealed that individuals with the ALDH2 wild-type genotype were more likely to have high MoCA scores than those with the mutant and heterozygous types (p = 0.034). In addition, using two MoCA cutoff scores, the percentage of moderate to excessive alcohol consumption in the cognitive impairment group was higher than that in the nonimpairment group (p = 0.001). The levels of 4-hydroxy-2-nonenal (p = 0.001) and swallowing function (p = 0.001) were also higher in the cognitive impairment group than in the nonimpairment group. Moreover, after adjusting for other potential risk factors, ALDH2 polymorphisms and alcohol consumption had a significant synergistic effect on cognitive impairment (p = 0.022). Specifically, the ALDH2∗2 mutant allele and higher alcohol consumption were associated with cognitive impairment and swallowing ability after ischemic stroke. Targeting ALDH2 may be a useful biomarker for cognitive rehabilitation following ischemic stroke.

Polyphenols and Ischemic Stroke: Insight into One of the Best Strategies for Prevention and Treatment

Ischemic stroke (IS) is still among the leading causes of death and disability worldwide. The pathogenic mechanisms beyond its development are several and are complex and this is the main reason why a functional therapy is still missed. The beneficial effects of natural compounds against cardiovascular diseases and IS have been investigated for a long time. In this article, we reviewed the association between the most studied polyphenols and stroke protection in terms of prevention, effect on acute phase, and rehabilitation. We described experimental and epidemiological studies reporting the role of flavonols, phenolic acid, and stilbens on ischemic mechanisms leading to stroke. We analyzed the principal animal models used to evaluate the impact of these micronutrients to cerebral blood flow and to molecular pathways involved in oxidative stress and inflammation modulation, such as sirtuins. We reported the most significant clinical trials demonstrated as the persistent use of polyphenols is clinically relevant in terms of the reduction of vascular risk factors for IS, such as Atrial Fibrillation. Interestingly, different kinds of polyphenols provide brain protection by activating different pathways and mechanisms, like inducing antithrombotic effect, such as Honokiol. For this reason, we discussed an appropriate integrative use of them as a possible therapeutic alternative against stroke.

Aldehyde Dehydrogenase 2 Protects Against Lipopolysaccharide-Induced Myocardial Injury by Suppressing Mitophagy

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis-induced circulatory and cardiac dysfunction is associated with high mortality rates. Mitophagy, a specific form of autophagy, is excessively activated in lipopolysaccharide-induced myocardial injury. The present study investigated whether aldehyde dehydrogenase 2 (ALDH2) regulates mitophagy in sepsis-induced myocardial dysfunction. After lipopolysaccharide administration, cardiac dysfunction, inflammatory cell infiltration, biochemical indicators of myocardial cell injury, and cardiomyocyte apoptosis were ameliorated in mice by ALDH2 activation or overexpression. In contrast, cardiac dysfunction and cardiomyocyte apoptosis were exacerbated in mice followed ALDH2 inhibition. Moreover, ALDH2 activation or overexpression regulated mitophagy by suppressing the expression of phosphatase and tensin homolog-induced putative kinase 1 (PINK1)/Parkin, by preventing the accumulation of 4-hydroxy-trans-nonenal. Conversely, ALDH2 inhibition promoted the expression of LC3B by increasing 4-hydroxy-trans-2-nonenal accumulation. Consequently, ALDH2 may protect the heart from lipopolysaccharide-induced injury by suppressing PINK1/Parkin-dependent mitophagy.

Autophagy is Involved in Neuroprotective Effect of Alpha7 Nicotinic Acetylcholine Receptor on Ischemic Stroke

The α7 nicotinic acetylcholine receptor (α7nAChR) belongs to the superfamily of cys loop cationic ligand-gated channels, which consists of homogeneous α7 subunits. Although our lab found that activation of α7nAChR could alleviate ischemic stroke, the mechanism is still unknown. Herein, we explored whether autophagy is involved in the neuroprotective effect mediated by α7nAChR in ischemic stroke. Transient middle cerebral artery occlusion (tMCAO) and oxygen and glucose deprivation (OGD/R) exposure were applied to in vivo and in vitro models of ischemic stroke, respectively. Neurological deficit score and infarct volume were used to evaluate outcomes of tMCAO in the in vivo study. Autophagy-related proteins were detected by Western blot, and autophagy flux was detected by using tandem fluorescent mRFP-GFP-LC3 lentivirus. At 24 h after tMCAO, α7nAChR knockout mice showed worse neurological function and larger infarct volume than wild-type mice. PNU282987, an α7nAChR agonist, protected against OGD/R-induced neuronal injury, enhanced autophagy, and promoted autophagy flux. However, the beneficial effects of PNU282987 were eliminated by 3-methyladenine (3-MA), an autophagy inhibitor. Moreover, we found that PNU282987 treatment could activate the AMPK-mTOR-p70S6K signaling pathway in the in vitro study, while the effect was attenuated by compound C, an AMPK inhibitor. Our results demonstrated that the beneficial effect on neuronal survival via activation of α7nAChR was associated with enhanced autophagy, and the AMPK-mTOR-p70S6K signaling pathway was involved in α7nAChR activation-mediated neuroprotection.

Transcriptional Silencing of ALDH2 Confers a Dependency on Fanconi Anemia Proteins in Acute Myeloid Leukemia

Hundreds of genes become aberrantly silenced in acute myeloid leukemia (AML), with most of these epigenetic changes being of unknown functional consequence. Here, we demonstrate how gene silencing can lead to an acquired dependency on the DNA repair machinery in AML. We make this observation by profiling the essentiality of the ubiquitination machinery in cancer cell lines using domain-focused CRISPR screening, which revealed Fanconi anemia (FA) proteins UBE2T and FANCL as unique dependencies in AML. We demonstrate that these dependencies are due to a synthetic lethal interaction between FA proteins and aldehyde dehydrogenase 2 (ALDH2), which function in parallel pathways to counteract the genotoxicity of endogenous aldehydes. We show DNA hypermethylation and silencing of ALDH2 occur in a recurrent manner in human AML, which is sufficient to confer FA pathway dependency. Our study suggests that targeting of the ubiquitination reaction catalyzed by FA proteins can eliminate ALDH2-deficient AML. SIGNIFICANCE: Aberrant gene silencing is an epigenetic hallmark of human cancer, but the functional consequences of this process are largely unknown. In this study, we show how an epigenetic alteration leads to an actionable dependency on a DNA repair pathway through the disabling of genetic redundancy.This article is highlighted in the In This Issue feature, p. 2113.

Acetaldehyde Dehydrogenase 2 regulates HMG-CoA reductase stability and cholesterol synthesis in the liver

HMG-CoA reductase (HMGCR) is the rate-limiting enzyme in cholesterol biosynthesis and the target for cholesterol-lowering therapy. Acetaldehyde dehydrogenase 2 (ALDH2) is primarily responsible for detoxifying ethanol-derived acetaldehyde and endogenous lipid aldehydes derived from lipid peroxidation. Epidemiological and Genome Wide Association Studies (GWAS) have linked an inactive ALDH2 rs671 variant, responsible for alcohol flush in nearly 8% world population and 40% of Asians, with cholesterol levels and higher risk of cardiovascular disease (CVD) but the underlying mechanism remains elusive. Here we find that the cholesterol levels in the serum and liver of ALDH2 knockout (AKO) and ALDH2 rs671 knock-in (AKI) mice are significantly increased, consistent with the increase of intermediates in the cholesterol biosynthetic pathways. Mechanistically, mitochondrial ALDH2 translocates to the endoplasmic reticulum to promote the formation of GP78/Insig1/HMGCR complex to increase HMGCR degradation through ubiquitination. Conversely, ALDH2 mutant or ALDH2 deficiency in AKI or AKO mice stabilizes HMGCR, resulting in enhanced cholesterol synthesis, which can be reversed by Lovastatin. Moreover, ALDH2-regulated cholesterol synthesis is linked to the formation of mitochondria-associated endoplasmic reticulum membranes (MAMs). Together, our study has identified that ALDH2 is a novel regulator of cholesterol synthesis, which may play an important role in CVD.

The discovery of novel small molecule allosteric activators of aldehyde dehydrogenase 2

Aldehyde dehydrogenase 2 (ALDH2) plays important role in ethanol metabolism, and also serves as an important shield from the damage occurring under oxidative stress. A special inactive variant was found carried by 35-45% of East Asians. The variant carriers have recently been found at the higher risk for the diseases related to the damage occurring under oxidative stress, such as cardiovascular and cerebrovascular diseases. As a result, ALDH2 activators may potentially serve as a new class of therapeutics. Herein, N-benzylanilines were found as novel allosteric activators of ALDH2 by computational virtual screening using ligand-based and structure-based screening parallel screening strategy. Then a structural optimization was performed and has led to the discovery of the compound C6. It has good activity in vitro and in vivo, which could reduce infarct size by ∼70% in ischemic stroke rat models. This study provided good lead compounds for the further development of ALDH2 activators.