ALDH2 in alcoholic heart diseases: molecular mechanism and clinical implications

Alcoholic Cardiomyopathy in Patients With Advanced Alcoholic Liver Disease: Single-Center Experience and Review of Literature

The impact of excessive alcohol on human health is associated with a lifetime cumulative use of alcohol and is further affected by various factors such as age, gender, nutritional status, concurrent cigarette smoking or drug use, diabetes, obesity, other cardiovascular diseases, and socio-economic status. Alcohol cardiomyopathy (ACM) is a type of acquired dilated cardiomyopathy, which is associated with long-term heavy alcohol consumption with historical rates varying from 3.8% to 47 % among patients with heart failure. Data regarding the prevalence of concurrent ACM in patients with alcoholic liver disease is limited. Among 483 patients with advanced liver disease who underwent liver transplant evaluation at a single transplant center during 2016-2021, based on screening transthoracic echocardiogram and a clear definition, none (0%) of the patients had alcoholic cardiomyopathy (range ejection fraction: 55-80%), 7% had left ventricular dilation (mild dilation: 82%), and 12.4% had diastolic dysfunction. We also review data regarding known risk factors, natural progression, and treatment of ACM, and further explore the evidence regarding the concurrence of alcohol-associated disease in liver with other organs such as heart and pancreas. In persons with excessive alcohol consumption, abstinence from alcohol or moderating its use has been shown to help decrease the progression of heart failure, arrythmias, and hypertension as well as liver dysfunction. Focus on the identification of both genetic markers and modifiable risk factors associated with various organ injuries in conjunction with public health policies for the safe use of alcohol is needed to mitigate the risk of alcohol use disorder.

The role of ALDHs in lipid peroxidation-related diseases

Lipid peroxidation presents the oxidative degradation of polyunsaturated fatty acids lincited by reactive species. Excessive accumulation of lipid peroxidation byproducts, including 4-hydroxy-2-nonenal (4-HNE) and malondialdehyde (MDA), causes protein dysfunction and various illnesses. Aldehyde dehydrogenases (ALDHs) catalyze the metabolism of both endogenous and exogenous aldehydes. These enzymes participate in detoxification and intermediary metabolism. Contemporary research has affirmed the involvement of both enzymatic and non-enzymatic pathways of ALDHs in modulating the evolution of diseases associated with lipid peroxidation. This review provides an overview of the biological functions and clinical implications concerning the enzymatic and non-enzymatic pathways of ALDHs in diseases related to lipid peroxidation, such as, non-alcoholic fatty liver disease (NAFLD), atherosclerosis, and type 2 diabetes (T2DM). Furthermore, the activators or inhibitors of ALDHs represent a promising therapeutic strategy for lipid peroxidation-related diseases.

Ethanol enhances selenoprotein P expression via ERK-FoxO3a axis in HepG2 cells

Drinking alcohol is considered one of the risk factors for development of diabetes mellitus. Recently, it was reported that selenoprotein P levels in blood are increased by ethanol intake. However, the mechanism by which ethanol increases selenoprotein P has not been elucidated. The expression of selenoprotein P protein and its mRNA were increased in a concentration- and time-dependent manner when human liver-derived HepG2 cells were treated with ethanol. Levels of AMPK and JNK proteins, which have been known to regulate selenoprotein P transcription, were unchanged by ethanol treatment. However, the amount of nuclear FoxO3a, a transcription factor of SeP, was increased. This was associated with dephosphorylation of ERK1 but not ERK2. It was found that ERK1 was dephosphorylated by activation of dual-specific phosphatase 5 and dual-specific phosphatase 6. However, the phosphorylation of MEK by ERK phosphokinase was not affected by ethanol treatment. These results suggest that the ethanol-induced increase in SeP levels occurs by enhanced transcription of SeP mRNA via the DUSP5/6-ERK1-FoxO3a pathway.

Alcoholic cardiomyopathy: an update

Alcohol-induced cardiomyopathy (AC) is an acquired form of dilated cardiomyopathy (DCM) caused by prolonged and heavy alcohol intake in the absence of other causes. The amount of alcohol required to produce AC is generally considered as >80 g/day over 5 years, but there is still some controversy regarding this definition. This review on AC focuses on pathogenesis, which involves different mechanisms. Firstly, the direct toxic effect of ethanol promotes oxidative stress in the myocardium and activation of the renin-angiotensin system. Moreover, acetaldehyde, the best-studied metabolite of alcohol, can contribute to myocardial damage impairing actin-myosin interaction and producing mitochondrial dysfunction. Genetic factors are also involved in the pathogenesis of AC, with DCM-causing genetic variants in patients with AC, especially titin-truncating variants. These findings support a double-hit hypothesis in AC, combining genetics and environmental factors. The synergistic effect of alcohol with concomitant conditions such as hypertension or liver cirrhosis can be another contributing factor leading to AC. There are no specific cardiac signs and symptoms in AC as compared with other forms of DCM. However, natural history of AC differs from DCM and relies directly on alcohol withdrawal, as left ventricular ejection fraction recovery in abstainers is associated with an excellent prognosis. Thus, abstinence from alcohol is the most crucial step in treating AC, and specific therapies are available for this purpose. Otherwise, AC should be treated according to current guidelines of heart failure with reduced ejection fraction. Targeted therapies based on AC pathogenesis are currently being developed and could potentially improve AC treatment in the future.

Elevated levels of alcohol dehydrogenase aggravate ethanol-evoked cardiac remodeling and contractile anomalies through FKBP5-yap-mediated regulation of ferroptosis and ER stress

Alcohol intake provokes severe organ injuries including alcoholic cardiomyopathy with hallmarks of cardiac remodeling and contractile defects. This study examined the toxicity of facilitated ethanol metabolism in alcoholism-evoked changes in myocardial morphology and contractile function, insulin signaling and various cell death domains using cardiac-selective overexpression of alcohol dehydrogenase (ADH). WT and ADH mice were offered an alcohol liquid diet for 12 weeks prior to assessment of cardiac geometry, function, ER stress, apoptosis and ferroptosis. Alcohol intake provoked pronounced glucose intolerance, cardiac remodeling and contractile anomalies with apoptosis, ER stress, and ferroptosis, the effects were accentuated by ADH with the exception of global glucose intolerance. Hearts from alcohol ingesting mice displayed dampened insulin-stimulated phosphorylation of insulin receptor (tyr1146) and IRS-1 (tyrosine) along with elevated IRS-1 serine phosphorylation, the effect was augmented by ADH. Alcohol challenge dampened phosphorylation of Akt and GSK-3β, and increased phosphorylation of c-Jun and JNK, the effects were accentuated by ADH. Alcohol challenge promoted ER stress, FK506 binding protein 5 (FKBP5), YAP, apoptosis and ferroptosis, the effects were exaggerated by ADH. Using a short-term ethanol challenge model (3 g/kg, i.p., twice in three days), we found that inhibition of FKBP5-YAP signaling or facilitated ethanol detoxification by Alda-1 alleviated ethanol cardiotoxicity. In vitro study revealed that the ethanol metabolite acetaldehyde evoked cardiac contractile anomalies, lipid peroxidation, and apoptosis, the effects of which were mitigated by Alda-1, inhibition of ER stress, FKBP5 and YAP. These data suggest that facilitated ethanol metabolism via ADH exacerbates alcohol-evoked myocardial remodeling, functional defects, and insulin insensitivity possibly through a FKBP5-YAP-associated regulation of ER stress and ferroptosis.

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 on diabetes remains elusive. This study examined the effects of ALDH2 overexpression and knockout on diabetic cardiomyopathy and the mechanism involved with a focus on mitochondrial integrity. Mice challenged with streptozotocin (STZ, 200 mg/kg, via intraperitoneal injection) exhibited pathological alterations, including reduced respiratory exchange ratio, dampened fractional shortening and ejection fraction, increased left ventricular end-systolic and diastolic diameters, cardiac remodeling, cardiomyocyte contractile anomalies, intracellular Ca2+ defects, myocardial ultrastructural injury, oxidative stress, apoptosis, and mitochondrial damage, which were overtly attenuated or accentuated by ALDH2 overexpression or knockout, respectively. Diabetic patients also exhibited reduced plasma ALDH2 activity, cardiac remodeling, and diastolic dysfunction. In addition, STZ challenge altered expression levels of mitochondrial proteins (PGC-1α and UCP2) and Ca2+ regulatory proteins (SERCA, Na+-Ca2+ exchanger, and phospholamban), dampened autophagy and mitophagy (LC3B ratio, TOM20, Parkin, FUNDC1, and BNIP3), disrupted phosphorylation of Akt, GSK3β, and Foxo3a, and elevated PTEN phosphorylation, most of which were reversed or worsened by ALDH2 overexpression or knockout, respectively. Furthermore, the novel ALDH2 activator torezolid, as well as the classical ALDH2 activator Alda-1, protected against STZ- or high glucose-induced in vivo or in vitro cardiac anomalies, which was nullified by inhibition of Akt, GSK3β, Parkin, or mitochondrial coupling. Our data discerned a vital role for ALDH2 in diabetic cardiomyopathy possibly through regulation of Akt and GSK3β activation, Parkin mitophagy, and mitochondrial function.

LncRNA CHKB-DT Downregulation Enhances Dilated Cardiomyopathy Through ALDH2

BACKGROUND

Human cardiac long noncoding RNA (lncRNA) profiles in patients with dilated cardiomyopathy (DCM) were previously analyzed, and the long noncoding RNA CHKB (choline kinase beta) divergent transcript (CHKB-DT) levels were found to be mostly downregulated in the heart. In this study, the function of CHKB-DT in DCM was determined.

METHODS

Long noncoding RNA expression levels in the human heart tissues were measured via quantitative reverse transcription-polymerase chain reaction and in situ hybridization assays. A CHKB-DT heterozygous or homozygous knockout mouse model was generated using the clustered regularly interspaced palindromic repeat (CRISPR)/CRISPR-associated protein 9 system, and the adeno-associated virus with a cardiac-specific promoter was used to deliver the RNA in vivo. Sarcomere shortening was performed to assess the primary cardiomyocyte contractility. The Seahorse XF cell mitochondrial stress test was performed to determine the energy metabolism and ATP production. Furthermore, the underlying mechanisms were explored using quantitative proteomics, ribosome profiling, RNA antisense purification assays, mass spectrometry, RNA pull-down, luciferase assay, RNA-fluorescence in situ hybridization, and Western blotting.

RESULTS

CHKB-DT levels were remarkably decreased in patients with DCM and mice with transverse aortic constriction-induced heart failure. Heterozygous knockout of CHKB-DT in cardiomyocytes caused cardiac dilation and dysfunction and reduced the contractility of primary cardiomyocytes. Moreover, CHKB-DT heterozygous knockout impaired mitochondrial function and decreased ATP production as well as cardiac energy metabolism. Mechanistically, ALDH2 (aldehyde dehydrogenase 2) was a direct target of CHKB-DT. CHKB-DT physically interacted with the mRNA of ALDH2 and fused in sarcoma (FUS) through the GGUG motif. CHKB-DT knockdown aggravated ALDH2 mRNA degradation and 4-HNE (4-hydroxy-2-nonenal) production, whereas overexpression of CHKB-DT reversed these molecular changes. Furthermore, restoring ALDH2 expression in CHKB-DT+/- mice alleviated cardiac dilation and dysfunction.

CONCLUSIONS

CHKB-DT is significantly downregulated in DCM. CHKB-DT acts as an energy metabolism-associated long noncoding RNA and represents a promising therapeutic target against DCM.

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.

A patent review on aldehyde dehydrogenase inhibitors: an overview of small molecule inhibitors from the last decade

INTRODUCTION

Physiological and pathophysiological effects arising from detoxification of aldehydes in humans implicate the enzyme aldehyde dehydrogenase (ALDH) gene family comprising of 19 isoforms. The main function of this enzyme family is to metabolize reactive aldehydes to carboxylic acids. Dysregulation of ALDH activity has been associated with various diseases. Extensive research has since gone into studying ALHD isozymes, their structural biology and developing small-molecule inhibitors. Novel chemical strategies to enhance the selectivity of ALDH inhibitors have now appeared.

AREAS COVERED

A comprehensive review of patent literature related to aldehyde dehydrogenase inhibitors in the last decade and half (2007-2022) is provided.

EXPERT OPINION

Aldehyde dehydrogenase (ALDH) is an important enzyme that metabolizes reactive exogenous and endogenous aldehydes in the body through NAD(P)±dependent oxidation. Hence this family of enzymes possess important physiological as well as toxicological roles in human body. Significant efforts in the field have led to potent inhibitors with approved clinical agents for alcohol use disorder therapy. Further clinical translation of novel compounds targeting ALDH inhibition will validate the promised therapeutic potential in treating many human diseases.The scientific/patent literature has been searched on SciFinder-n, Reaxys, PubMed, Espacenet and Google Patents. The search terms used were 'ALDH inhibitors', 'Aldehyde Dehydrogenase Inhibitors'.

Rapid and accurate genotyping of human SNP rs671 in aldehyde dehydrogenase 2 gene using one-step CRISPR/Cas12b assay without DNA amplification

BACKGROUND

The SNP rs671 of Human aldehyde dehydrogenase (ALDH) is G-A transition at 1510th nucleotides, which is an important clinical indicator of alcoholic liver disease, digestive tract cancer and some drug efficiency. The commonly used genotyping assay of this polymorphism is relatively time-consuming and costly.

FINDING

This study develops a rapid and accurate one-step CRISPR/Cas12b assay to distinguish the G1510A polymorphism of human ALDH2 free of DNA amplification. The method we established requires only one step of adding 1 μl genomic DNA sample to premixed system, and waiting for the acquisition of fluorescent signal, taking approximate 30 min.

CONCLUSIONS

This method provides a potential tool for more accurate and reliable nucleic acid detection with a single base difference and supports the relevant disease diagnosis and personalized 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.

A Common East Asian aldehyde dehydrogenase 2*2 variant promotes ventricular arrhythmia with chronic light-to-moderate alcohol use in mice

Chronic heavy alcohol use is associated with lethal arrhythmias. Whether common East Asian-specific aldehyde dehydrogenase deficiency (ALDH2*2) contributes to arrhythmogenesis caused by low level alcohol use remains unclear. Here we show 59 habitual alcohol users carrying ALDH2 rs671 have longer QT interval (corrected) and higher ventricular tachyarrhythmia events compared with 137 ALDH2 wild-type (Wt) habitual alcohol users and 57 alcohol non-users. Notably, we observe QT prolongation and a higher risk of premature ventricular contractions among human ALDH2 variants showing habitual light-to-moderate alcohol consumption. We recapitulate a human electrophysiological QT prolongation phenotype using a mouse ALDH2*2 knock-in (KI) model treated with 4% ethanol, which shows markedly reduced total amount of connexin43 albeit increased lateralization accompanied by markedly downregulated sarcolemmal Nav1.5, Kv1.4 and Kv4.2 expressions compared to EtOH-treated Wt mice. Whole-cell patch-clamps reveal a more pronounced action potential prolongation in EtOH-treated ALDH2*2 KI mice. By programmed electrical stimulation, rotors are only provokable in EtOH-treated ALDH2*2 KI mice along with higher number and duration of ventricular arrhythmia episodes. The present research helps formulate safe alcohol drinking guideline for ALDH2 deficient population and develop novel protective agents for these subjects.

Substance use disorders and treatment in Asian American and Pacific Islander women: A scoping review

BACKGROUND AND OBJECTIVES

Asian American Pacific Islanders (AAPIs) face unique barriers in seeking treatment for substance use disorders (SUD) and are less likely than the general population to receive treatment. Barriers specific to AAPI women may be especially significant given identified gender and racial differences in SUD prevalence and treatment. This review examines rates of SUD in AAPI women and summarizes the literature on SUD treatment for AAPI women.

METHODS

Data from 2016 to 2019 National Survey on Drug Use and Health (NSDUH) surveys were extracted to summarize rates of SUD. A scoping review of the literature on AAPI women and SUD treatment was conducted; eight articles published from 2010 to present were reviewed.

RESULTS

The prevalence of SUDs among AAPI women increased overall, although rates of SUDs were generally lower in AAPI women compared to their male counterparts. Patterns of gender differences in SUDs varied for subpopulations of AAPI women. There is limited research on treatment utilization and access for AAPI women. The few studies that examined treatment outcomes found favorable outcomes for AAPI women; research on culturally adapted interventions was promising but nascent.

DISCUSSION AND CONCLUSIONS

Literature on SUD treatment for AAPI women is limited. The availability of more culturally tailored treatments addressing the specific needs of AAPI women may lead to more acceptability and treatment utilization for this group. Additional research is needed to elucidate the unique barriers to treatment AAPI women face.

SCIENTIFIC SIGNIFICANCE

With rising rates of substance use in AAPI women, there is a need to develop and test effective SUD treatments adapted for AAPI women.

Ethanol Metabolism and Melanoma

Malignant melanoma is the deadliest form of skin cancer. Despite significant efforts in sun protection education, melanoma incidence is still rising globally, drawing attention to other socioenvironmental risk factors for melanoma. Ethanol and acetaldehyde (AcAH) are ubiquitous in our diets, medicines, alcoholic beverages, and the environment. In the liver, ethanol is primarily oxidized to AcAH, a toxic intermediate capable of inducing tumors by forming adducts with proteins and DNA. Once in the blood, ethanol and AcAH can reach the skin. Although, like the liver, the skin has metabolic mechanisms to detoxify ethanol and AcAH, the risk of ethanol/AcAH-associated skin diseases increases when the metabolic enzymes become dysfunctional in the skin. This review highlights the evidence linking cutaneous ethanol metabolism and melanoma. We summarize various sources of skin ethanol and AcAH and describe how the reduced activity of each alcohol metabolizing enzyme affects the sensitivity threshold to ethanol/AcAH toxicity. Data from the Gene Expression Omnibus database also show that three ethanol metabolizing enzymes (alcohol dehydrogenase 1B, P450 2E1, and catalase) and an AcAH metabolizing enzyme (aldehyde dehydrogenase 2) are significantly reduced in melanoma tissues.

Aldehyde dehydrogenase 2 alleviates mitochondrial dysfunction by promoting PGC-1α-mediated biogenesis in acute kidney injury

Renal tubular epithelial cells are one of the high energy-consuming cell types, which mainly depend on mitochondrial energy supply. Aldehyde dehydrogenase 2 (ALDH2) is a key enzyme that is involved in alcohol metabolism and mitochondrial oxidative ATP production; however, its function in mitochondrial homoeostasis in acute kidney injury (AKI) is unclear. Here, we found that ALDH2 expression was predominantly decreased in cisplatin or maleic acid (MA) models both in vivo and in vitro. ALDH2 knockout (KO) mice exhibited exacerbated kidney impairment and apoptosis of tubular epithelial cells after cisplatin injection. In contrast, ALDH2 activation alleviated AKI and tubular cell apoptosis in both cisplatin- and MA-induced models. RNA sequencing revealed that the oxidative phosphorylation pathway was positively enriched in the renal tissues after Alda-1 pre-treatment in MA-induced mice. ALDH2 activation restored mitochondrial structure, mitochondrial membrane potential, and respiration rate, but downregulated glycolysis in MA-induced mice and human renal proximal tubular epithelial (HK-2) cells. Mechanistically, co-immunoprecipitation assays revealed that ALDH2 interacts with peroxisomal proliferator-γ coactivator-1α (PGC-1α), a master regulator of mitochondrial biogenesis, and advanced its nuclear translocation. Subsequently, PGC-1α knockdown almost abolished the improvement of ALDH2 activation on MA-induced tubular epithelial cells damage. Thus, our study revealed that ALDH2 activation alleviated mitochondrial dysfunction in AKI by enhancing PGC-1α-mediated mitochondrial biogenesis. Hence, ALDH2 may act as a potential therapeutic target to prevent AKI progression.

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.

Protective effects of isoflavones on alcoholic liver diseases: Computational approaches to investigate the inhibition of ALDH2 with isoflavone analogues

Excessive and chronic alcohol intake can lead to the progression of alcoholic liver disease (ALD), which is a major cause of morbidity and mortality worldwide. ALD encompasses a pathophysiological spectrum such as simple steatosis, alcoholic steatohepatitis (ASH), fibrosis, alcoholic cirrhosis, and hepatocellular carcinoma (HCC). Aldehyde dehydrogenase (ALDH2) is the most vital enzyme that produces acetate from acetaldehyde and is expressed at high levels in the liver, kidneys, muscles, and heart. The ALDH2*2 allele is found in up to 40% of East Asian populations, and has a significant impact on alcohol metabolism. Interestingly, several studies have shown that individuals with ALDH2 deficiency are more susceptible to liver inflammation after drinking alcohol. Furthermore, there is growing evidence of an association between ALDH2 deficiency and the development of cancers in the liver, stomach, colon, and lung. Isoflavone analogues are low molecular-weight compounds derived from plants, similar in structure and activity to estrogen in mammals, known as phytoestrogens. Recent studies have reported that isoflavone analogues have beneficial effects on the progression of ALD. This mini-review summarizes the current knowledge about the roles of isoflavone analogues in ALD and discusses the therapeutic potential of isoflavone analogues in liver pathophysiology. In particular, we highlight the significance of computational approaches in this field.

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.

Deficiency in Beclin1 attenuates alcohol-induced cardiac dysfunction via inhibition of ferroptosis

BACKGROUND

Binge drinking leads to compromised mitochondrial integrity and contractile function in the heart although little effective remedy is readily available. Given the possible derangement of autophagy in ethanol-induced cardiac anomalies, this study was designed to examine involvement of Beclin1 in acute ethanol-induced cardiac contractile dysfunction, in any, and the impact of Beclin1 haploinsufficiency on ethanol cardiotoxicity with a focus on autophagy-related ferroptosis.

METHODS

WT and Beclin1 haploinsufficiency (BECN^+/-) mice were challenged with ethanol for one week (2 g/kg, i.p. on day 1, 3 and 7) prior to assessment of cardiac injury markers (LDH, CK-MB), cardiac geometry, contractile and mitochondrial integrity, oxidative stress, lipid peroxidation, apoptosis and ferroptosis.

RESULTS

Ethanol exposure compromised cardiac geometry and contractile function accompanied with upregulated Beclin1 and autophagy, mitochondrial injury, oxidative stress, lipid peroxidation and apoptosis, and ferroptosis (GPx4, SLC7A11, NCOA4). Although Beclin1 deficiency did not affect cardiac function in the absence of ethanol challenge, it alleviated ethanol-induced changes in cardiac injury biomarkers, cardiomyocyte area, interstitial fibrosis, echocardiographic and cardiomyocyte mechanical properties along with mitochondrial integrity, oxidative stress, lipid peroxidation, apoptosis and ferroptosis. Ethanol challenge evoked pronounced ferroptosis (downregulated GPx4, SLC7A11 and elevated NCOA4, lipid peroxidation), the effect was alleviated by Beclin1 haploinsufficiency. Inhibition of ferroptosis using LIP-1 rescued ethanol-induced cardiac mechanical anomalies. In vitro study noted that ferroptosis induction using erastin abrogated Beclin1 haploinsufficiency-induced response against ethanol.

CONCLUSIONS

In sum, our data suggest that Beclin1 haploinsufficiency benefits acute ethanol challenge-induced myocardial remodeling and contractile dysfunction through ferroptosis-mediated manner.

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.

Polydatin attenuates chronic alcohol consumption-induced cardiomyopathy through a SIRT6-dependent mechanism

Polydatin has attracted much attention as a potential cardioprotective agent against ischemic heart disease and diabetic cardiomyopathy. However, the effect and mechanism of polydatin supplementation on alcoholic cardiomyopathy (ACM) are still unknown. This study aimed to determine the therapeutic effect of polydatin against ACM and to explore the molecular mechanisms with a focus on SIRT6-AMP-activated protein kinase (AMPK) signaling and mitochondrial function. The ACM model was established by feeding C57/BL6 mice with an ethanol Lieber-DeCarli diet for 12 weeks. The mice received polydatin (20 mg kg^-1) or vehicle treatment. We showed that polydatin treatment not only improved cardiac function but also reduced myocardial fibrosis and dynamin-related protein 1 (Drp-1)-mediated mitochondrial fission, and enhanced PTEN-induced putative kinase 1 (PINK1)-Parkin-dependent mitophagy in alcohol-treated myocardium. Importantly, these beneficial effects were mimicked by SIRT6 overexpression but abolished by the infection of recombinant serotype 9 adeno-associated virus (AAV9) carrying SIRT6-specific small hairpin RNA. Mechanistically, alcohol consumption induced a gradual decrease in the myocardial SIRT6 level, while polydatin effectively activated SIRT6-AMPK signaling and modulated mitochondrial dynamics and mitophagy, thus reducing oxidative stress damage and preserving mitochondrial function. In summary, these data present new information regarding the therapeutic actions of polydatin, suggesting that the activation of SIRT6 signaling may represent a new approach for tackling ACM-related cardiac dysfunction.

Large and Small Animal Models of Heart Failure With Reduced Ejection Fraction

Heart failure (HF) describes a heterogenous complex spectrum of pathological conditions that results in structural and functional remodeling leading to subsequent impairment of cardiac function, including either systolic dysfunction, diastolic dysfunction, or both. Several factors chronically lead to HF, including cardiac volume and pressure overload that may result from hypertension, valvular lesions, acute, or chronic ischemic injuries. Major forms of HF include hypertrophic, dilated, and restrictive cardiomyopathy. The severity of cardiomyopathy can be impacted by other comorbidities such as diabetes or obesity and external stress factors. Age is another major contributor, and the number of patients with HF is rising worldwide in part due to an increase in the aged population. HF can occur with reduced ejection fraction (HF with reduced ejection fraction), that is, the overall cardiac function is compromised, and typically the left ventricular ejection fraction is lower than 40%. In some cases of HF, the ejection fraction is preserved (HF with preserved ejection fraction). Animal models play a critical role in facilitating the understanding of molecular mechanisms of how hearts fail. This review aims to summarize and describe the strengths, limitations, and outcomes of both small and large animal models of HF with reduced ejection fraction that are currently used in basic and translational research. The driving defect is a failure of the heart to adequately supply the tissues with blood due to impaired filling or pumping. An accurate model of HF with reduced ejection fraction would encompass the symptoms (fatigue, dyspnea, exercise intolerance, and edema) along with the pathology (collagen fibrosis, ventricular hypertrophy) and ultimately exhibit a decrease in cardiac output. Although countless experimental studies have been published, no model completely recapitulates the full human disease. Therefore, it is critical to evaluate the strength and weakness of each animal model to allow better selection of what animal models to use to address the scientific question proposed.

Aldehyde dehydrogenase 2 and arrhythmogenesis

Cardiac arrhythmia is a common cardiovascular disease that leads to considerable economic burdens and significant global public health challenges. Despite the remarkable progress made in recent decades, antiarrhythmic therapy remains suboptimal. Aldehyde dehydrogenase 2 (ALDH2), a critical detoxifying enzyme, catalyzes toxic aldehydes and protects individuals from damages caused by oxidative stress. Accumulating evidence has demonstrated that ALDH2 activation has potential antiarrhythmic benefits. The correlation between ALDH2 deficiency and arrhythmogenesis has been widely recognized. In this review, we summarize recent researches on the potential roles of ALDH2 activation and antiarrhythmic protection, as well as the role played by the ALDH2*2 polymorphism (rs671) in promoting arrhythmic risk. Additionally, we discuss important new findings illustrating the use of ALDH2 activators, which may prove to be promising antiarrhythmic therapy agents.

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.

Associations of Alcohol Dehydrogenase and Aldehyde Dehydrogenase Polymorphism With Cognitive Impairment Among the Oldest-Old in China

Recent literature suggested that ALDH2 mutation is associated with alcohol metabolism, and ethanol intake might jointly increase the risk of Alzheimer’s disease (AD) in mice. However, it is unclear whether this synergistic effect exists among humans. We examined the associations of four single nucleotide polymorphisms (SNPs) on aldehyde dehydrogenase (ALDH) and alcohol dehydrogenase (ADH) genes (i.e., ALDH2 rs671, ADH1B rs1229984, ADH1B rs1042026, and ADH1C rs1693482) and cognitive impairment among the oldest-old. We also investigated whether this association was modified by ethanol intake from alcohol consumption. Data were from the Chinese Longitudinal Healthy Longevity Survey genetic sub-study, including 1,949 participants aged over 90 years. Participants with a Mini-Mental State Examination (MMSE) score of < 18 were considered cognitively impaired. Alcohol consumption was categorized as heavy, moderate, or never drinkers. With the dominant model, carrying A allele on rs671, C allele on rs1229984, and T allele on rs1042026 was associated with 33% (95% confidence interval [CI]: 5%, 69%), 33% (95% CI: 2%, 75%), and 29% (95% CI: 3%, 62%) higher odds of cognitive impairment in the multivariable-adjusted logistic model, respectively. We did not observe a significant interaction between those SNPs and alcohol consumption. Among the oldest-old, carrying ALDH2 rs671 mutation was associated with higher odds of cognitive impairment independent of alcohol consumption.

Accumulation of acetaldehyde in aldh2.1 zebrafish causes increased retinal angiogenesis and impaired glucose metabolism

Reactive carbonyl species (RCS) are spontaneously formed in the metabolism and modify and impair the function of DNA, proteins and lipids leading to several organ complications. In zebrafish, knockout of the RCS detoxifying enzymes glyoxalase 1 (Glo 1), aldehyde dehydrogenase 3a1 (Aldh3a1) and aldo-ketoreductase 1a1a (Akr1a1a) showed a signature of elevated RCS which specifically regulated glucose metabolism, hyperglycemia and diabetic organ damage. aldh2.1 was compensatory upregulated in glo1^−/− animals and therefore this study aimed to investigate the detoxification ability for RCS by Aldh2.1 in zebrafish independent of ethanol exposure. aldh2.1 knockout zebrafish were generated using CRISPR/Cas9 and subsequently analyzed on a histological, metabolomic and transcriptomic level. aldh2.1^−/− zebrafish displayed increased endogenous acetaldehyde (AA) inducing an increased angiogenesis in retinal vasculature. Expression and pharmacological interventional studies identified an imbalance of c-Jun N-terminal kinase (JNK) and p38 MAPK induced by AA, which mediate an activation of angiogenesis. Moreover, increased AA in aldh2.1^−/− zebrafish did not induce hyperglycemia, instead AA inhibited the expression of glucokinase (gck) and glucose-6-phosphatase (g6pc), which led to an impaired glucose metabolism. In conclusion, the data have identified AA as the preferred substrate for Aldh2.1's detoxification ability, which subsequently causes microvascular organ damage and impaired glucose metabolism.

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ALDH2.1 was compensatory upregulated in glyoxalase 1 zebrafish mutants.

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Loss of ALDH2.1 increases acetaldehyde leading to vascular retinal alterations.

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Acetaldehyde controls glucose metabolism via glucose-6-phosphate and glucokinase.

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Altered JNK and p38 cause microvascular complications.

Behavioral consequences of the downstream products of ethanol metabolism involved in alcohol use disorder

Research concerning Alcohol Use Disorder (AUD) has previously focused primarily on either the behavioral or chemical consequences experienced following ethanol intake, but these areas of research have rarely been considered in tandem. Compared with other drugs of abuse, ethanol has been shown to have a unique metabolic pathway once it enters the body, which leads to the formation of downstream metabolites which can go on to form biologically active products. These metabolites can mediate a variety of behavioral responses that are commonly observed with AUD, such as ethanol intake, reinforcement, and vulnerability to relapse. The following review considers the preclinical and chemical research implicating these downstream products in AUD and proposes a chemobehavioral model of AUD.

Epigenetic modification in alcohol use disorder and alcoholic cardiomyopathy: From pathophysiology to therapeutic opportunities

Alcohol consumption prompts detrimental psychological, pathophysiological and health issues, representing one of the major causes of death worldwide. Alcohol use disorder (AUD), which is characterized by compulsive alcohol intake and loss of control over alcohol usage, arises from a complex interplay between genetic and environmental factors. More importantly, long-term abuse of alcohol is often tied with unfavorable cardiac remodeling and contractile alterations, a cadre of cardiac responses collectively known as alcoholic cardiomyopathy (ACM). Recent evidence has denoted a pivotal role for ethanol-triggered epigenetic modifications, the interface between genome and environmental cues, in the organismal and cellular responses to ethanol exposure. To-date, three major epigenetic mechanisms (DNA methylation, histone modifications, and RNA-based mechanisms) have been identified for the onset and development of AUD and ACM. Importantly, these epigenetic changes induced by alcohol may be detectable in the blood, thus offering diagnostic, therapeutic, and prognostic promises of epigenetic markers for AUD and alcoholic complications. In addition, several epigenetic drugs have shown efficacies in the management of alcohol abuse, loss of control for alcohol usage, relapse, drinking-related anxiety and behavior in withdrawal. In this context, medications targeting epigenetic modifications may hold promises for pharmaceutical management of AUD and ACM.

Pharmacological Activation Of Aldehyde Dehydrogenase 2 Protects Against Heatstroke-Induced Acute Lung Injury by Modulating Oxidative Stress and Endothelial Dysfunction

Heatstroke (HS) can cause acute lung injury (ALI). Heat stress induces inflammation and apoptosis via reactive oxygen species (ROS) and endogenous reactive aldehydes. Endothelial dysfunction also plays a crucial role in HS-induced ALI. Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that detoxifies aldehydes such as 4-hydroxy-2-nonenal (4-HNE) protein adducts. A single point mutation in ALDH2 at E487K (ALDH2*2) intrinsically lowers the activity of ALDH2. Alda-1, an ALDH2 activator, attenuates the formation of 4-HNE protein adducts and ROS in several disease models. We hypothesized that ALDH2 can protect against heat stress-induced vascular inflammation and the accumulation of ROS and toxic aldehydes. Homozygous ALDH2*2 knock-in (KI) mice on a C57BL/6J background and C57BL/6J mice were used for the animal experiments. Human umbilical vein endothelial cells (HUVECs) were used for the in vitro experiment. The mice were directly subjected to whole-body heating (WBH, 42°C) for 1 h at 80% relative humidity. Alda-1 (16 mg/kg) was administered intraperitoneally prior to WBH. The severity of ALI was assessed by analyzing the protein levels and cell counts in the bronchoalveolar lavage fluid, the wet/dry ratio and histology. ALDH2*2 KI mice were susceptible to HS-induced ALI in vivo. Silencing ALDH2 induced 4-HNE and ROS accumulation in HUVECs subjected to heat stress. Alda-1 attenuated the heat stress-induced activation of inflammatory pathways, senescence and apoptosis in HUVECs. The lung homogenates of mice pretreated with Alda-1 exhibited significantly elevated ALDH2 activity and decreased ROS accumulation after WBH. Alda-1 significantly decreased the WBH-induced accumulation of 4-HNE and p65 and p38 activation. Here, we demonstrated the crucial roles of ALDH2 in protecting against heat stress-induced ROS production and vascular inflammation and preserving the viability of ECs. The activation of ALDH2 by Alda-1 attenuates WBH-induced ALI in vivo.

Activation of Aldehyde Dehydrogenase 2 Ameliorates Glucolipotoxicity of Pancreatic Beta Cells

Chronic hyperglycemia and hyperlipidemia hamper beta cell function, leading to glucolipotoxicity. Mitochondrial aldehyde dehydrogenase 2 (ALDH2) detoxifies reactive aldehydes, such as methylglyoxal (MG) and 4-hydroxynonenal (4-HNE), derived from glucose and lipids, respectively. We aimed to investigate whether ALDH2 activators ameliorated beta cell dysfunction and apoptosis induced by glucolipotoxicity, and its potential mechanisms of action. Glucose-stimulated insulin secretion (GSIS) in MIN6 cells and insulin secretion from isolated islets in perifusion experiments were measured. The intracellular ATP concentrations and oxygen consumption rates of MIN6 cells were assessed. Furthermore, the cell viability, apoptosis, and mitochondrial and intracellular reactive oxygen species (ROS) levels were determined. Additionally, the pro-apoptotic, apoptotic, and anti-apoptotic signaling pathways were investigated. We found that Alda-1 enhanced GSIS by improving the mitochondrial function of pancreatic beta cells. Alda-1 rescued MIN6 cells from MG- and 4-HNE-induced beta cell death, apoptosis, mitochondrial dysfunction, and ROS production. However, the above effects of Alda-1 were abolished in Aldh2 knockdown MIN6 cells. In conclusion, we reported that the activator of ALDH2 not only enhanced GSIS, but also ameliorated the glucolipotoxicity of beta cells by reducing both the mitochondrial and intracellular ROS levels, thereby improving mitochondrial function, restoring beta cell function, and protecting beta cells from apoptosis and death.

trans-Fatty Acids as an Enhancer of Inflammation and Cell Death: Molecular Basis for Their Pathological Actions

trans-Fatty acids (TFAs) are food-derived fatty acids that possess one or more trans double bonds between carbon atoms. Compelling epidemiological and clinical evidence has demonstrated the association of TFA consumption with various diseases, such as cardiovascular diseases, and neurodegenerative diseases. However, the underlying etiology is poorly understood since the mechanisms of action of TFAs remain to be clarified. Previous studies have shown that single treatment with TFAs induce inflammation and cell death, but to a much lesser extent than saturated fatty acids (SFAs) that are well established as a risk factor for diseases linked with inflammation and cell death, which cannot explain the particularly higher association of TFAs with atherosclerosis than SFAs. In our series of studies, we have established the role of TFAs as an enhancer of inflammation and cell death. We found that pretreatment with TFAs strongly promoted apoptosis induced by either extracellular ATP, one of the damage-associated molecular patterns (DAMPs) leaked from damaged cells, or DNA damaging-agents, including doxorubicin and cisplatin, thorough enhancing activation of the stress-responsive mitogen-activated protein (MAP) kinase p38/c-jun N-terminal kinase (JNK) pathways; pretreatment with SFAs or cis isomers of TFAs had only minor or no effect, suggesting the uniqueness of the pro-apoptotic role of TFAs among fatty acids. Our findings will provide an insight into understanding of the pathogenesis mechanisms, and open up a new avenue for developing prevention strategies and therapies for TFA-related diseases.

Current View on the Mechanisms of Alcohol-Mediated Toxicity

Alcohol is a psychoactive substance that is widely used and, unfortunately, often abused. In addition to acute effects such as intoxication, it may cause many chronic pathological conditions. Some of the effects are very well described and explained, but there are still gaps in the explanation of empirically co-founded dysfunction in many alcohol-related conditions. This work focuses on reviewing actual knowledge about the toxic effects of ethanol and its degradation products.

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.

trans-Fatty acids promote p53-dependent apoptosis triggered by cisplatin-induced DNA interstrand crosslinks via the Nox-RIP1-ASK1-MAPK pathway

trans-Fatty acids (TFAs) are food-derived fatty acids associated with various diseases including cardiovascular diseases. However, the underlying etiology is poorly understood. Here, we show a pro-apoptotic mechanism of TFAs such as elaidic acid (EA), in response to DNA interstrand crosslinks (ICLs) induced by cisplatin (CDDP). We previously reported that TFAs promote apoptosis induced by doxorubicin (Dox), a double strand break (DSB)-inducing agent, via a non-canonical apoptotic pathway independent of tumor suppressor p53 and apoptosis signal-regulating kinase (ASK1), a reactive oxygen species (ROS)-responsive kinase. However, here we found that in the case of CDDP-induced apoptosis, EA-mediated pro-apoptotic action was reversed by knockout of either p53 or ASK1, despite no increase in p53 apoptotic activity. Upon CDDP treatment, EA predominantly enhanced ROS generation, ASK1-p38/c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) pathway activation, and ultimately cell death, all of which were suppressed either by co-treatment of the NADPH oxidase (Nox) inhibitor Apocynin, or by knocking out its regulatory protein, receptor-interacting protein 1 (RIP1). These results demonstrate that in response to CDDP ICLs, TFAs promote p53-dependent apoptosis through the enhancement of the Nox-RIP1-ASK1-MAPK pathway activation, providing insight into the diverse pathogenetic mechanisms of TFAs according to the types of DNA damage.

A narrative review of chronic alcohol-induced atrial fibrillation

Alcohol use disorder (AUD) is highly prevalent and can lead to many cardiovascular complications, including arrhythmias. Chronic alcohol use has a dose-dependent relationship with incidence of atrial fibrillation (AF), where higher alcohol intake (>3 drinks a day) is associated with higher risk of AF. Meanwhile, low levels of chronic alcohol intake (<1 drink a day) is not associated with increased risk of AF. Mechanistically, chronic alcohol intake alters the structural, functional and electrical integrity of the atria, predisposing to AF. Increased screening can help identify AUD patients early on and provide the opportunity to educate on chronic alcohol use related risks, such as AF. The ideal treatment to reduce risk of incident or recurrent AF in AUD populations is abstinence.

Electronic cigarette solvents, pulmonary irritation, and endothelial dysfunction: role of acetaldehyde and formaldehyde

After more than a decade of electronic cigarette (E-cig) use in the United States, uncertainty persists regarding E-cig use and long-term cardiopulmonary disease risk. As all E-cigs use propylene glycol and vegetable glycerin (PG-VG) and generate abundant saturated aldehydes, mice were exposed by inhalation to PG-VG-derived aerosol, formaldehyde (FA), acetaldehyde (AA), or filtered air. Biomarkers of exposure and cardiopulmonary injury were monitored by mass spectrometry (urine metabolites), radiotelemetry (respiratory reflexes), isometric myography (aorta), and flow cytometry (blood markers). Acute PG-VG exposure significantly affected multiple biomarkers including pulmonary reflex (decreased respiratory rate, -50%), endothelium-dependent relaxation (-61.8 ± 4.2%), decreased WBC (-47 ± 7%), and, increased RBC (+6 ± 1%) and hemoglobin (+4 ± 1%) versus air control group. Notably, FA exposure recapitulated the prominent effects of PG-VG aerosol on pulmonary irritant reflex and endothelial dysfunction, whereas AA exposure did not. To attempt to link PG-VG exposure with FA or AA exposure, urinary formate and acetate levels were measured by GC-MS. Although neither FA nor AA exposure altered excretion of their primary metabolite, formate or acetate, respectively, compared with air-exposed controls, PG-VG aerosol exposure significantly increased post-exposure urinary acetate but not formate. These data suggest that E-cig use may increase cardiopulmonary disease risk independent of the presence of nicotine and/or flavorings. This study indicates that FA levels in tobacco product-derived aerosols should be regulated to levels that do not induce biomarkers of cardiopulmonary harm. There remains a need for reliable biomarkers of exposure to inhaled FA and AA.NEW & NOTEWORTHY Use of electronic cigarettes (E-cig) induces endothelial dysfunction (ED) in healthy humans, yet the specific constituents in E-cig aerosols that contribute to ED are unknown. Our study implicates formaldehyde that is formed in heating of E-cig solvents (propylene glycol, PG; vegetable glycerin, VG). Exposure to formaldehyde or PG-VG-derived aerosol alone stimulated ED in female mice. As ED was independent of nicotine and flavorants, these data reflect a "universal flaw" of E-cigs that use PG-VG.Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/e-cigarettes-aldehydes-and-endothelial-dysfunction/.

Advanced glycation end products (AGEs) and other adducts in aging-related diseases and alcohol-mediated tissue injury

Advanced glycation end products (AGEs) are potentially harmful and heterogeneous molecules derived from nonenzymatic glycation. The pathological implications of AGEs are ascribed to their ability to promote oxidative stress, inflammation, and apoptosis. Recent studies in basic and translational research have revealed the contributing roles of AGEs in the development and progression of various aging-related pathological conditions, such as diabetes, cardiovascular complications, gut microbiome-associated illnesses, liver or neurodegenerative diseases, and cancer. Excessive chronic and/or acute binge consumption of alcohol (ethanol), a widely consumed addictive substance, is known to cause more than 200 diseases, including alcohol use disorder (addiction), alcoholic liver disease, and brain damage. However, despite the considerable amount of research in this area, the underlying molecular mechanisms by which alcohol abuse causes cellular toxicity and organ damage remain to be further characterized. In this review, we first briefly describe the properties of AGEs: their formation, accumulation, and receptor interactions. We then focus on the causative functions of AGEs that impact various aging-related diseases. We also highlight the biological connection of AGE-alcohol-adduct formations to alcohol-mediated tissue injury. Finally, we describe the potential translational research opportunities for treatment of various AGE- and/or alcohol-related adduct-associated disorders according to the mechanistic insights presented.

Metabolic Aspects of Anthracycline Cardiotoxicity

OPINION STATEMENT

Heart failure (HF) is increasingly recognized as the major complication of chemotherapy regimens. Despite the development of modern targeted therapies such as monoclonal antibodies, doxorubicin (DOXO), one of the most cardiotoxic anticancer agents, still remains the treatment of choice for several solid and hematological tumors. The insurgence of cardiotoxicity represents the major limitation to the clinical use of this potent anticancer drug. At the molecular level, cardiac side effects of DOXO have been associated to mitochondrial dysfunction, DNA damage, impairment of iron metabolism, apoptosis, and autophagy dysregulation. On these bases, the antioxidant and iron chelator molecule, dexrazoxane, currently represents the unique FDA-approved cardioprotectant for patients treated with anthracyclines.A less explored area of research concerns the impact of DOXO on cardiac metabolism. Recent metabolomic studies highlight the possibility that cardiac metabolic alterations may critically contribute to the development of DOXO cardiotoxicity. Among these, the impairment of oxidative phosphorylation and the persistent activation of glycolysis, which are commonly observed in response to DOXO treatment, may undermine the ability of cardiomyocytes to meet the energy demand, eventually leading to energetic failure. Moreover, increasing evidence links DOXO cardiotoxicity to imbalanced insulin signaling and to cardiac insulin resistance. Although anti-diabetic drugs, such as empagliflozin and metformin, have shown interesting cardioprotective effects in vitro and in vivo in different models of heart failure, their mechanism of action is unclear, and their use for the treatment of DOXO cardiotoxicity is still unexplored.This review article aims at summarizing current evidence of the metabolic derangements induced by DOXO and at providing speculations on how key players of cardiac metabolism could be pharmacologically targeted to prevent or cure DOXO cardiomyopathy.

Schisandrin B Protects against Acute Ethanol-Induced Cardiac Injury by Downregulating Autophagy via the NOX4/ROS Pathway

INTRODUCTION

Although oxidative stress has been demonstrated to mediate acute ethanol-induced changes in autophagy in the heart, the precise mechanism behind redox regulation in acute ethanol heart disease remains largely unknown.

METHODS

Wild-type C57BL/6 mice were intraperitoneally injected with ethanol (3 g/kg/day) for 3 consecutive days. The effects of ethanol on cultured primary cardiomyocytes and H9c2 myoblasts were also studied in vitro. Levels of autophagic flux, cardiac apoptosis and function, reactive oxygen species (ROS) accumulation, NOX4, and NOX2 were examined. The NOX4 gene was knocked down with NOX4 siRNA.

RESULTS

In this study, we demonstrated that schisandrin B inhibited acute ethanol-induced autophagy and sequent apoptosis. In addition, schisandrin B treatment improved cardiac function in ethanol-treated mice. Furthermore, NOX4 protein expression was increased during acute ethanol exposure, and the upregulation of NOX4 was significantly inhibited by schisandrin B treatment. The knockdown of NOX4 prevented ROS accumulation, cell autophagy, and apoptosis.

CONCLUSION

These results highlight that NOX4 is a critical mediator of ROS and elaborate the role of the NOX4/ROS axis in the effect of schisandrin B on autophagy and autophagy-mediated apoptosis in acute ethanol exposure, which suggests a therapeutic strategy for acute alcoholic cardiomyopathy.

Deletion of the E3 ubiquitin ligase, Parkin, exacerbates chronic alcohol intake-induced cardiomyopathy through an Ambra1-dependent mechanism

BACKGROUND AND PURPOSE

Chronic alcohol consumption contributes to contractile dysfunction and unfavourable geometric changes in myocardium, accompanied by altered autophagy and disturbed mitochondrial homeostasis. The E3 ubiquitin ligase Parkin encoded by PARK2 gene maintains a fundamental role in regulating mitophagy and mitochondrial homeostasis, although little is known of its role in the aetiology of alcoholic cardiomyopathy. Here we assessed the effects of Parkin deletion in chronic alcohol-evoked cardiotoxicity.

EXPERIMENTAL APPROACH

Following alcohol (4%) or control diet intake for 8 weeks, adult male wild-type (WT) and PARK2 knockout (Parkin^-/- ) mice were examined using echocardiography. Cardiomyocyte mechanical properties, morphology of myocardium, and mitochondrial damage were also evaluated. Autophagy and mitophagy levels were assessed by LC3B and GFP-LC3 puncta, and lysosome-dependent autophagic flux was scrutinized using GFP-mRFP-LC3 puncta and Bafilomycin A1 treatment.

KEY RESULTS

Chronic alcohol exposure provoked unfavourable geometric changes in myocardium and led to mitochondrial dysfunction and cardiac contractile defects, effects further exacerbated by Parkin knockout. Chronic alcohol exposure provoked autophagy and PINK1/Parkin-mediated mitophagy without affecting lysosome-dependent autophagic flux, the effects of which were diminished by Parkin deletion. Parkin adenovirus infection in neonatal rat cardiomyocytes further increased autophagy and protected against alcohol-induced myocardial injury, effects blocked by siRNA for Ambra1 (Autophagy and Beclin1 regulator 1). Immunofluorescence staining and co-immunoprecipitation assays showed interactions between Parkin and Ambra1.

CONCLUSIONS AND IMPLICATIONS

Parkin was essential for cardiac homeostasis in alcohol challenge, accompanied by increased autophagy/mitophagy and maintenance of mitochondrial integrity through its interaction with Ambra1.

Toxic Effects of Methamphetamine on Perivascular Health: Co-morbid Effects of Stress and Alcohol Use Disorders

Methamphetamine (Meth) abuse presents a global problem and commonly occurs with stress and/or alcohol use disorders. Regardless, the biological causes and consequences of these comorbidities are unclear. Whereas the mechanisms of Meth, stress, and alcohol abuse have been examined individually and well-characterized, these processes overlap significantly and can impact the neural and peripheral consequences of Meth. This review focuses on the deleterious cardio- and cerebrovascular effects of Meth, stress, alcohol abuse, and their comorbid effects on the brain and periphery. Points of emphasis are on the composition of the blood-brain barrier and their effects on the heart and vasculature. The autonomic nervous system, inflammation, and oxidative stress are specifically highlighted as common mediators of the toxic consequences to vascular and perivascular health. A significant portion of the Meth abusing population also presents with stress and alcohol use disorders, prompting a need to understand the mechanisms underlying their comorbidities. Little is known about their possible convergent effects. Therefore, the purpose of this critical review is to identify shared mechanisms of Meth, chronic stress, and alcohol abuse that contributes to the dysfunction of vascular health and underscores the need for studies that directly address their interactions.

C-reactive protein as a possible marker for severity and mortality of COVID-19 infection

AIM

The present study aimed to introduce a possible biomarker to differentiate between severe and fatal conditions of COVID-19.

BACKGROUND

The COVID-19 pandemic, appearing as a complicated health problem, has changed the lifestyle of people in recent years. Clinical findings indicate mild, severe, and fatal conditions of this disease. Prediction of disease severity is a significant point in managing COVID-19 infection.

METHODS

In this study, 195 differentially expressed genes (DEGs) that discriminate between fatal and severe conditions in patients were extracted from the literature and screened to determine the significant ones. The significant DEGs plus the 90 first neighbors added from the STRING database were included in the interactome using Cytoscape software v 3.7.2. The central nodes of the analyzed network were identified and assessed.

RESULTS

Ten significant DEGs were candidates for assessment, of which 9 were recognized by the STRING database. IL6, ALB, TNF, CRP, INS, MPO, C3, CXCL8, TTR, and TLR4 were determined as central nodes; IL6, CRP, and TTR were highlighted as the critical genes related to the severity of COVID-19 infection.

CONCLUSION

CRP was identified as the best possible biomarker with levels related to the severity and fatality of COVID-19 infection.

Genetic Variants behind Cardiovascular Diseases and Dementia

Cardiovascular diseases (CVDs) and dementia are the leading causes of disability and mortality. Genetic connections between cardiovascular risk factors and dementia have not been elucidated. We conducted a scoping review and pathway analysis to reveal the genetic associations underlying both CVDs and dementia. In the PubMed database, literature was searched using keywords associated with diabetes mellitus, hypertension, dyslipidemia, white matter hyperintensities, cerebral microbleeds, and covert infarctions. Gene lists were extracted from these publications to identify shared genes and pathways for each group. This included high penetrance genes and single nucleotide polymorphisms (SNPs) identified through genome wide association studies. Most risk SNPs to both diabetes and dementia participate in the phospholipase C enzyme system and the downstream nositol 1,4,5-trisphosphate and diacylglycerol activities. Interestingly, AP-2 (TFAP2) transcription factor family and metabolism of vitamins and cofactors were associated with genetic variants that were shared by white matter hyperintensities and dementia, and by microbleeds and dementia. Variants shared by covert infarctions and dementia were related to VEGF ligand-receptor interactions and anti-inflammatory cytokine pathways. Our review sheds light on future investigations into the causative relationships behind CVDs and dementia, and can be a paradigm of the identification of dementia treatments.

Bone marrow stromal cells induce an ALDH+ stem cell-like phenotype and enhance therapy resistance in AML through a TGF-β-p38-ALDH2 pathway

The bone marrow microenvironment (BME) in acute myeloid leukemia (AML) consists of various cell types that support the growth of AML cells and protect them from chemotherapy. Mesenchymal stromal cells (MSCs) in the BME have been shown to contribute immensely to leukemogenesis and chemotherapy resistance in AML cells. However, the mechanism of stroma-induced chemotherapy resistance is not known. Here, we hypothesized that stromal cells promote a stem-like phenotype in AML cells, thereby inducing tumorigenecity and therapy resistance. To test our hypothesis, we co-cultured AML cell lines and patient samples with BM-derived MSCs and determined aldehyde dehydrogenase (ALDH) activity and performed gene expression profiling by RNA sequencing. We found that the percentage of ALDH+ cells increased dramatically when AML cells were co-cultured with MSCs. However, among the 19 ALDH isoforms, ALDH2 and ALDH1L2 were the only two that were significantly upregulated in AML cells co-cultured with stromal cells compared to cells cultured alone. Mechanistic studies revealed that the transforming growth factor-β1 (TGF-β1)-regulated gene signature is activated in AML cells co-cultured with MSCs. Knockdown of TGF-β1 in BM-MSCs inhibited stroma-induced ALDH activity and ALDH2 expression in AML cells, whereas treatment with recombinant TGF-β1 induced the ALDH+ phenotype in AML cells. We also found that TGF-β1-induced ALDH2 expression in AML cells is mediated by the non-canonical pathway through the activation of p38. Interestingly, inhibition of ALDH2 with diadzin and CVT-10216 significantly inhibited MSC-induced ALDH activity in AML cells and sensitized them to chemotherapy, even in the presence of MSCs. Collectively, BM stroma induces ALDH2 activity in AML cells through the non-canonical TGF-β pathway. Inhibition of ALDH2 sensitizes AML cells to chemotherapy.

NO66 overexpression rescues ethanol-induced cell apoptosis in human AC16 cardiomyocytes by suppressing PTEN and activating the PI3K/Akt signaling

Previously, Nucleolar protein 66 (NO66) was reported to be closely associated with alcohol exposure-induced injury. However, the role of NO66 in alcohol-induced cytotoxicity remains unclear. In this study, we explored the potential effect and mechanism of NO66 on ethanol-induced apoptosis in human AC16 cardiomyocytes. The AC16 cell lines with NO66 and phosphatase and tensin homolog (PTEN) overexpression were constructed. Cell counting kit-8 (CCK-8), lactate dehydrogenase (LDH) assay, Annexin V-FITC/PI staining, and flow cytometry were used to evaluate the cell viability, membrane damage, and apoptosis, respectively. Quantitative real-time PCR (qRT-PCR) and western blot analysis were applied to measure mRNA and protein expression. The results showed that acute ethanol exposure markedly augmented cytotoxicity and reduced NO66 level in AC16 cardiomyocytes. Overexpression of NO66 partially reversed ethanol-induced apoptosis. NO66 upregulation reversed the decrease in phosphorylation of protein kinase B (Akt) and B-cell lymphoma-2/Bcl-2-associated x (Bcl-2/Bax) ratio and the increase in PTEN, p53, and caspase-3 activity induced by ethanol treatment. Meanwhile, the application of PI3K inhibitor (LY294002) and PTEN overexpression attenuated the inhibition efficiency of NO66 on cell apoptosis. In addition, PTEN overexpression weakened the effect of NO66 on PI3K/Akt activation, without affecting the level of NO66. Our data suggested that NO66 overexpression might play an anti-apoptotic role in ethanol-induced cell injury via reducing PTEN and upregulating the PI3K/Akt pathway.

Mitochondrial Ca2+ regulation in the etiology of heart failure: physiological and pathophysiological implications

Heart failure (HF) represents one of the leading causes of cardiovascular diseases with high rates of hospitalization, morbidity and mortality worldwide. Ample evidence has consolidated a crucial role for mitochondrial injury in the progression of HF. It is well established that mitochondrial Ca²⁺ participates in the regulation of a wide variety of biological processes, including oxidative phosphorylation, ATP synthesis, reactive oxygen species (ROS) generation, mitochondrial dynamics and mitophagy. Nonetheless, mitochondrial Ca²⁺ overload stimulates mitochondrial permeability transition pore (mPTP) opening and mitochondrial swelling, resulting in mitochondrial injury, apoptosis, cardiac remodeling, and ultimately development of HF. Moreover, mitochondria possess a series of Ca²⁺ transport influx and efflux channels, to buffer Ca²⁺ in the cytoplasm. Interaction at mitochondria-associated endoplasmic reticulum membranes (MAMs) may also participate in the regulation of mitochondrial Ca²⁺ homeostasis and plays an essential role in the progression of HF. Here, we provide an overview of regulation of mitochondrial Ca²⁺ homeostasis in maintenance of cardiac function, in an effort to identify novel therapeutic strategies for the management of HF.

Parkin deficiency accentuates chronic alcohol intake-induced tissue injury and autophagy defects in brain, liver and skeletal muscle

Alcoholism leads to organ injury including mitochondrial defect and apoptosis with evidence favoring a role for autophagy dysregulation in alcoholic damage. Parkin represents an autosomal recessive inherited gene for Parkinson's disease and an important member of selective autophagy for mitochondria. The association between Parkinson's disease and alcoholic injury remains elusive. This study aimed to examine the effect of parkin deficiency on chronic alcohol intake-induced organ injury in brain, liver and skeletal muscle (rectus femoris muscle). Adult parkin-knockout (PRK-/-) and wild-type mice were placed on Liber-De Carli alcohol liquid diet (4%) for 12 weeks prior to assessment of liver enzymes, intraperitoneal glucose tolerance, protein carbonyl content, apoptosis, hematoxylin and eosin morphological staining, and mitochondrial respiration (cytochrome c oxidase, NADH:cytochrome c reductase and succinate:cytochrome c reductase). Autophagy protein markers were monitored by western blot analysis. Our data revealed that chronic alcohol intake imposed liver injury as evidenced by elevated aspartate aminotransferase and alanine transaminase, glucose intolerance, elevated protein carbonyl formation, apoptosis, focal inflammation, necrosis, microvesiculation, autophagy/mitophagy failure and dampened mitochondrial respiration (complex IV, complexes I and III, and complexes II and III) in the brain, liver and rectus femoris skeletal muscle. Although parkin ablation itself did not generate any notable effects on liver enzymes, insulin sensitivity, tissue carbonyl damage, apoptosis, tissue morphology, autophagy or mitochondrial respiration, it accentuated alcohol intake-induced tissue damage, apoptosis, morphological change, autophagy/mitophagy failure and mitochondrial injury without affecting insulin sensitivity. These data suggest that parkin plays an integral role in the preservation against alcohol-induced organ injury, apoptosis and mitochondrial damage.

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

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