ALDH2 Activity Research Articles

ALDH1A3 Regulations of Matricellular Proteins Promote Vascular Smooth Muscle Cell Proliferation.

SummaryVascular smooth muscle cell (VSMC) proliferation promotes intimal hyperplasia (IH) in occluding vascular diseases. Here we identified a positive role of ALDH1A3 (an aldehyde dehydrogenase) in this pro-IH process. The expression of ALDH1A3, but not that of 18 other isoforms of the ALDH family, was substantially increased in cytokine-stimulated VSMCs. PDGF(BB) stimulated VSMC total ALDH activity and proliferation, whereas ALDH1A3 silencing abolished this effect. ALDH1A3 silencing also diminished the expression of two matricellular proteins (TNC1 and ESM1), revealing a previously unrecognized ALDH1A3 function. Loss-of-function experiments demonstrated that TNC1 and ESM1 mediated ALDH1A3's pro-proliferative function via activation of AKT/mTOR and/or MEK/ERK pathways. Furthermore, ALDH inhibition with disulfiram blocked VSMC proliferation/migration in vitro and decreased TNC1 and ESM1 and IH in angioplasty-injured rat carotid arteries. Thus, ALDH1A3 promotes VSMC proliferation at least partially through TNC1/ESM1 upregulation; dampening excessive ALDH1A3 activity represents a potential approach to IH mitigation.

Alda-1 Prevents Pulmonary Epithelial Barrier Dysfunction following Severe Hemorrhagic Shock through Clearance of Reactive Aldehydes

Severe hemorrhagic shock and resuscitation (HS/R) can lead to lung injury, resulting in respiratory insufficiency. We investigated whether treatment with Alda-1, an ALDH2 activator, decreased lung injury induced by severe HS/R in a rat model. Male Sprague-Dawley rats were randomized into three groups, hemorrhagic shock + placebo, hemorrhagic shock + Alda-1, and sham. All animals were heparinized, and then 50% of the total calculated blood volume was collected over 60 minutes. After 40 minutes of hemorrhagic shock, animals were reinfused with the shed blood over 40 minutes and then observed for an additional 2 hours. Concentrations of 4-HNE, TNF-α, IL-6, and ALDH2 activity were detected; lung injury and lung wet-to-dry weight ratios were assessed. Expression of occludin and ZO-1 proteins in lung tissues was also determined. At 2 hours after resuscitation, lung injury was significantly reduced and the wet-to-dry weight ratio was notably decreased in the Alda-1 group compared with placebo (P<0.05). Alda-1 treatment also significantly increased the activity of ALDH2 and decreased the levels of toxic 4-HNE (P<0.05). In the Alda-1 group, IL-6 and TNF-α were dramatically decreased compared with placebo-treated animals (P<0.05). Expression of occludin and ZO-1 proteins was significantly decreased in the placebo group compared with the Alda-1 group (P<0.05). Thus, in a rat model of severe HS/R, treatment with Alda-1 increased the activity of ALDH2, significantly accelerated the clearance of reactive aldehydes, and concomitantly alleviated lung injury through improvement of pulmonary epithelial barrier integrity resulting in decreased alveolar epithelial tissue permeability, lung edema, and diffuse infiltration of inflammatory cells.

Abstract 879: Aldehyde Dehydrogenase Activator 1 (Alda-1) Attenuates Coronary Endothelial Dysfunction-Mediated Cardiac Damage in ALDH2*2 Diabetic Mice

Background: Endothelial dysfunction plays a critical role in the pathogenesis of diabetic complications. Diabetes-mediated reactive aldehydes like 4-hydroxy-2-nonenal (4HNE) are associated with endothelial cell impairment. Aldehyde dehydrogenase (ALDH) 2, a mitochondrial enzyme which detoxifies 4HNE, protects heart function against diabetic cardiomyopathy. Nearly 600 million East Asians have a point mutation of ALDH2, termed as ALDH2*2, which causes an intrinsic low ALDH2 activity. Previously, we reported an aggravated coronary endothelial dysfunction in ALDH2*2 mutant knock-in mice (ALDH2*2 mice) with diabetes. Aldehyde dehydrogenase activator 1 (Alda-1) is the only known activator for both normal ALDH2 and mutant ALDH2*2. We hypothesized that Alda-1 could protect endothelial cells (ECs) from hyperglycemia induced coronary endothelial dysfunction in diabetic ALDH2*2 mice. Methods and Results: Diabetes was induced by streptozotocin injection (150 mg/kg) to ALDH2*2 mice. Alda-1 (10 mg/kg/d, DM-A) or vehicle (DM-V) was delivered through mini-pumps for 3 weeks after diabetes. We found an increased left ventricular pressure (59.9±18.7 vs 66.4±20.1 mmHg) and a decreased perfusion pressure (89.4±8.1 vs 83.6±12.1 mmHg) in Langendorff hearts from DM-A (DM-V vs DM-A, p&lt;0.05, respectively). In heart sections, CD31+ (127.2±22.3 vs 270.5±53.7 /mm 2 ) and eNOS+ cells (136.2±22.8 vs 366.7±33.6 /mm 2 ) were increased while apoptosis (1117.5±303.6 vs 727.1±254.8 /mm 2 ) and 4HNE+ (515.8±8.3 vs 181.7±72.5 /mm 2 ) cells were reduced in DM-A (DM-V vs DM-A, p&lt;0.05, respectively). Direct perfusion of 4HNE to Langendorff hearts from control ALDH2*2 mice (4HNE) increased perfusion pressure (Δ3.18±0.5 vs Δ36.6±7.7 mmHg), arteriole closure (8.3±0.4 vs 39.8±3.7 /mm 2 ), and decreased eNOS+ cells (2877.1±117.3 vs 37.5±5.6 /mm 2 ) (Sham vs 4HNE, p&lt;0.05). One-day Alda-1 (10 mg/kg) pre-treatment before 4HNE perfusion (A-4HNE) decreased perfusion pressure (Δ7.1±1.7 mmHg), number of closed arterioles (22.4±4.8 /mm 2 ), and increased eNOS+ (878.0±121.3 /mm 2 ) cells (4HNE vs A-4HNE, p&lt;0.05, respectively). Conclusion: Alda-1 protects hyperglycemia mediated 4HNE induced coronary endothelial dysfunction and thereby cardiac tissue in ALDH2*2 diabetic mice.

Alda‐1 shields mitochondrial dynamic proteins from hyperoxia via Aldh2 activation

RationaleAcute respiratory distress syndrome (ARDS) is associated with fluid filled lungs and hypoxia. Thus, ARDS patients are placed on supplemental oxygen; however, hyperoxia can damage the lungs, cause mitochondrial dysfunction, and ultimately lead to acute lung injury in animal models of ARDS. Mitochondrial aldehyde dehydrogenase 2 (Aldh2) metabolizes dangerous, reactive products, such as 4‐hydroxynonenal, that otherwise causes oxidative stress. The focus of this research is to determine if Alda‐1, an Aldh2 activator enhances the activity of Aldh2, thus alleviating hyperoxia damage by preventing mitochondrial dysfunction and reducing immune cell infiltration. It also determined if administration of Alda‐1 recovers mitochondrial dynamics and reduces cytokine levels and immune cell infiltration.MethodsC57BL/6 mice were exposed to hyperoxia for 48 hours with DMSO (Control) and Alda‐1 (20 mM) via alzet pumps on the dorsal side of mice. The mice were divided into four groups: normoxia + DMSO (room air), normoxia + Alda‐1, hyperoxia + DMSO, and hyperoxia + Alda‐1. The lungs were harvested and the bronchoalveolar lavage (BAL) fluid was collected and analyzed by immunoblot and cytokine levels.ResultsImmunoblot analysis of lung lysate demonstrates that mice treated with Alda‐1, compared to mice treated with DMSO, during hyperoxia have decreased levels of OPA1 and Drp1, indicating that Alda‐1 shields against oxidative stress for proteins associated with mitochondrial dynamics. Moreover, the BAL fluid analysis reveals less infiltration of macrophages in mice treated with Alda‐1 versus mice treated with DMSO alone. These results indicate that activation of Aldh2 via Alda‐1 is protective against hyperoxia‐induced acute lung injury and may be a viable therapeutic agent for ARDS.ConclusionThese findings suggest that Alda‐1, an Aldh2 activator, maintains mitochondrial homeostasis and reduces immune cell infiltration in this mouse model of ARDS and may be a novel therapeutic agent in ARDS.Support or Funding InformationThis work is supported by NIH RO1 grant (HL105932) to N.K. and AHA grant (#17SDG32780002) to L.G.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Mitochondrial ALDH2 protects against lipopolysaccharide-induced myocardial contractile dysfunction by suppression of ER stress and autophagy

Lipopolysaccharide (LPS), an essential component of outer membrane of the Gram-negative bacteria, plays a pivotal role in myocardial anomalies in sepsis. Recent evidence depicted an essential role for mitochondrial aldehyde dehydrogenase (ALDH2) in cardiac homeostasis. This study examined the effect of ALDH2 on endotoxemia-induced cardiac anomalies. Echocardiographic, cardiac contractile and intracellular Ca2+ properties were examined. Our results indicated that LPS impaired cardiac contractile function (reduced fractional shortening, LV end systolic diameter, peak shortening, maximal velocity of shortening/relengthening, prolonged relengthening duration, oxidation of SERCA, and intracellular Ca2+ mishandling), associated with ER stress, inflammation, O2− production, increased autophagy, CAMKKβ, phosphorylated AMPK and suppressed phosphorylation of mTOR, the effects of which were significantly attenuated or negated by ALDH2. LPS promoted early endosomal formation (as evidenced by RAB4 and RAB5a), apoptosis and necrosis (MTT and LDH) while decreasing late endosomal formation (RAB7 and RAB 9), the effects were reversed by ALDH2. In vitro study revealed that LPS-induced SERCA oxidation, autophagy and cardiac dysfunction were abrogated by ALDH2 activator Alda-1, the ER chaperone TUDCA, the autophagy inhibitor 3-MA, or the AMPK inhibitor Compound C. The beneficial effect of Alda-1 against LPS was nullified by AMPK activator AICAR or rapamycin. CAMKKβ inhibition failed to rescue LPS-induced ER stress. Tunicamycin–induced cardiomyocyte dysfunction was ameliorated by Alda-1 and autophagy inhibition, the effect of which was abolished by rapamycin. These data suggested that ALDH2 protected against LPS-induced cardiac anomalies via suppression of ER stress, autophagy in a CAMKKβ/AMPK/mTOR-dependent manner.

Fenofibrate -a PPARα agonist- increases alcohol dehydrogenase levels in the liver: implications for its possible use as an ethanol-aversive drug.

After ethanol consumption, disulfiram increases blood-acetaldehyde levels, generating an aversive reaction that deters alcohol drinking. Given the major secondary effects of disulfiram, finding other effective drugs to reduce alcohol consumption in individuals with alcohol-use-disorder is highly desirable. It has been reported that administering fenofibrate to high-drinking rats increases hepatic catalase levels and blood acetaldehyde after administering ethanol and a 60-70% inhibition of voluntary alcohol intake. This work evaluated whether fenofibrate has an additional effect on the activity of other ethanol-metabolizing enzymes, which could contribute to the high acetaldehyde levels generated upon administering ethanol. Male high-drinker rats were allowed to voluntary drink 10% ethanol or water for 2 months. Subsequently, fenofibrate (100 mg/kg/day) or vehicle was administered orally for 14 days. Then, alcohol dehydrogenase (ADH1) and aldehyde dehydrogenase (ALDH2) protein levels and enzymatic activities in the livers were quantified. Fenofibrate treatment produced a marked increase in ADH1 protein levels (396% ± 18%, p < 0.001) and enzymatic activity (425% ± 25%, p < 0.001). Fenofibrate did not result in differences in ALDH2 activity or in ALDH2 protein levels. The studies show that treatment with fenofibrate not only increased the activity of catalase in the liver of alcohol-drinking rats, as reported earlier, but also increased the levels and enzymatic activity of ADH1, while ALDH2 remained unchanged. The increases in ADH1 contribute to explaining the remarkable effect of fenofibrate in raising blood levels of acetaldehyde in ethanol-consuming animals, in which a marked reduction of alcohol intake is recorded.

Systemic inactivation of hypoxia-inducible factor prolyl 4-hydroxylase 2 in mice protects from alcohol-induced fatty liver disease

Alcoholic fatty liver disease (AFLD) is a growing health problem for which no targeted therapy is available. We set out to study whether systemic inactivation of the main hypoxia-inducible factor prolyl 4-hydroxylase, HIF-P4H-2 (PHD2/EglN1), whose inactivation has been associated with protection against metabolic dysfunction, could ameliorate it. HIF-P4H-2-deficient and wild-type (WT) mice or HIF-P4H inhibitor-treated WT mice were subjected to an ethanol diet for 3–4 weeks and their metabolic health, liver and white adipose tissue (WAT) were analyzed. Primary hepatocytes from the mice were used to study cellular ethanol metabolism. The HIF-P4H-2-deficient mice retained a healthier metabolic profile, including less adiposity, better lipoprotein profile and restored insulin sensitivity, while on the ethanol diet than the WT. They also demonstrated protection from alcohol-induced steatosis and liver damage and had less WAT inflammation. In liver and WAT the expression of the key lipogenic and adipocytokine mRNAs, such as Fas and Ccl2, were downregulated, respectively. The upregulation of metabolic and antioxidant hypoxia-inducible factor (HIF) target genes, such as Slcs 16a1 and 16a3 and Gclc, respectively, and a higher catalytic activity of ALDH2 in the HIF-P4H-2-deficient hepatocytes improved handling of the toxic ethanol metabolites and oxidative stress. Pharmacological HIF-P4H inhibition in the WT mice phenocopied the protection against AFLD. Our data show that global genetic inactivation of HIF-P4H-2 and pharmacological HIF-P4H inhibition can protect mice from alcohol-induced steatosis and liver injury, suggesting that HIF-P4H inhibitors, now in clinical trials for renal anemia, could also be studied in randomized clinical trials for treatment of AFLD.

A physiological concentration of luteolin induces phase II drug-metabolizing enzymes through the ERK1/2 signaling pathway in HepG2 cells

The flavon luteolin has various health-promoting activities including cardiovascular protection, anti-inflammatory activity and anticancer activity. A serum concentration of about 100 nM luteolin is reached by dietary habit. However, little is known about the function of luteolin over its physiological concentration range. In this study, we investigated whether a physiological concentration of luteolin could activate nuclear factor-erythroid-2-related factor 2 (Nrf2)-mediated expression of phase II drug-metabolizing enzymes in human hepatoma HepG2 cells. Interestingly, less than 1 nM of luteolin could induce phase II drug-metabolizing enzymes, such as GSTs, HO-1, and NQO1. Both 1 and 100 nM luteolin increased expression and activity of ALDH2, which metabolized toxic acetaldehyde into nontoxic acetic acid. Luteolin increased nuclear accumulation of Nrf2 and enhanced the ARE-binding complex through increasing the stability of the Nrf2 protein. Luteolin increased phosphorylation of Nrf2 at Ser40, and MEK inhibitors (U0126 and PD98059) canceled luteolin-induced phosphorylation of Nrf2. Furthermore, luteolin increased modified Keap1. In conclusion, a physiological concentration of luteolin induces the expression of phase II drug-metabolizing enzymes by enhancement of Nrf2 nuclear accumulation through MEK1/2-ERK1/2-mediated phosphorylation of Nrf2, increasing Nrf2 stability and inducing a conformational change of Keap1.

Aldehyde Dehydrogenase (ALDH) 2 in Diabetic Heart Diseases.

A major pathophysiological mechanism behind the development of diabetic heart diseases is oxidative stress mediated by toxic reactive aldehydes such as 4-hydroxynonenal (4HNE). Aldehyde dehydrogenase (ALDH) 2 is a mitochondrial enzyme that has been found to detoxify these deleterious aldehydes and thereby mitigate cardiac damage. Furthermore, its protective role in cellular signaling reverses aberrations caused by hyperglycemia, thereby protecting cardiac function. This chapter assesses the role of ALDH2 in diabetic heart diseases by examining preclinical studies where ALDH2 activity is perturbed in both decreased and increased directions. In doing so, issues in improving ALDH2 activity in select human populations are elucidated, and further research directions are discussed.

Mitochondrial Aldehyde Dehydrogenase in Myocardial Ischemic and Ischemia-Reperfusion Injury.

Myocardial ischemia-reperfusion (IR) injury during acute myocardial infarction or open-heart surgery would promote oxidative stress, leading to the accumulation of reactive aldehydes that cause cardiac damage. It has been well demonstrated that aldehyde dehydrogenase (ALDH)-2 is an important cardioprotective enzyme for its central role in the detoxification of reactive aldehydes. ALDH2 activation by small molecule activators is a promising approach for cardioprotection for myocardial IR injury.

Inhalation exposure to low levels of ethyl tertiary butyl ether: Its genetic effects were significantly modified by ALDH2 activity.

Previous experiments showed that high concentrations of ethyl tertiary butyl ether (ETBE) exposure (500-5,000 ppm) significantly resulted in DNA damages in aldehyde dehydrogenase 2 (Aldh2) knockout (KO) mice. This study was aimed to verify the genotoxic effects in three genetic types, Aldh2 KO, heterogeneous (HT), and wild type (WT), of mice exposed to lower concentrations of ETBE (50-500 ppm) by inhalation. Histopathology assessments in the livers, measurements of genotoxic biomarkers in blood and livers, and urinary 8-hydroxydeoxyguanosion (8-OH-dG) for the oxidative DNA damage of whole body were performed. Significant histopathological changes and DNA strand breaks both in hepatocytes and leukocytes were found in HT and KO male mice exposed to ≥200 ppm ETBE, but not in 50 ppm ETBE. 8-OH-dG levels either in liver or urine were higher in the HT and KO male mice exposed to ≥200 ppm ETBE. The pathological and genetic effects of ETBE were almost at the same extents for HT and KO mice. Thus, 50 ppm could be the no observed adverse effect level for ETBE in HT and KO male mice, which was far lower than the 500 ppm in WT mice. These results suggested that decrease and deficiency of ALDH2 activity would significantly increase the sensitivity to ETBE-induced genotoxicity as well as hepatotoxic effects after exposure even to low concentrations of ETBE. Environ. Mol. Mutagen. 60: 145-153, 2019. © 2018 Wiley Periodicals, Inc.

Precision medicine approach: Empagliflozin for diabetic cardiomyopathy in mice with aldehyde dehydrogenase (ALDH) 2 * 2 mutation, a specific genetic mutation in millions of East Asians

A vast majority of type-2 diabetic patients (~65%) die of cardiovascular complications including heart failure (HF). In diabetic hearts, levels of 4-hydroxy-2-nonenal (4HNE), a reactive aldehyde that is produced upon lipid peroxidation, were increased. We also demonstrated that in diabetic hearts, there is a decrease in the activity of aldehyde dehydrogenase (ALDH) 2, a primary detoxifying enzyme present in cardiac mitochondria. A single point mutation at E487K of ALDH2 in East Asians known as ALDH2 * 2 intrinsically lowers ALDH2 activity. We hypothesize that Empagliflozin (EMP), a sodium-glucose cotransporter (SGLT) 2 inhibitor, can ameliorate diabetic cardiomyopathy by decreasing hyperglycemia-mediated 4HNE protein adducts in ALDH2 * 2 mutant mice which serve as a precision medicine tool as they mimic ALDH2 * 2 carriers. We induced type-2 diabetes in 11–14 month-old male and female ALDH2 * 2 mice through a high-fat diet. Chow-fed ALDH2 * 2 mice served as controls. At the end of 4 months, we treated the diabetic ALDH2 * 2 mice with EMP (3 mg/kg/d) or its vehicle (Veh). After 2 months of EMP treatment, cardiac function was assessed by conscious echocardiography after treadmill exercise stress. EMP improved the cardiac function and running distance and duration significantly compared to Veh-treated ALDH2 * 2 diabetic mice. These beneficial effects can be attributed to the EMP-mediated decrease in cardiac mitochondrial 4HNE adducts and increase in the levels of phospho AKT, AKT, phospho Akt substrate of 160 kDa (pAS160), AS160 and GLUT-4 in the skeletal muscle tissue of the ALDH2*2 mutant diabetic mice, respectively. Finally, our data implicate EMP can ameliorate diabetic cardiomyopathy in diabetic ALDH2 * 2 mutant patients.

Correction: Type-2 diabetic aldehyde dehydrogenase 2 mutant mice (ALDH 2*2) exhibiting heart failure with preserved ejection fraction phenotype can be determined by exercise stress echocardiography.

[This corrects the article DOI: 10.1371/journal.pone.0195796.].

Association of low-activity ALDH2 and alcohol consumption with risk of esophageal cancer in Chinese adults: A population-based cohort study.

Existing evidence remains inconclusive as to how the association between inactive ALDH2 and esophageal cancer (EC) depends on alcohol consumption. The study is based on the China Kadoorie Biobank cohort, with 10 years follow‐up of 0.5 million adults aged 30–79 years. ALDH2 activity was assessed by both self‐reported flushing response and Glu504Lys (rs671 G > A) polymorphism. Among both male and female participants who consumed alcohol less than weekly (n = 69,519; 211 EC cases), low active or inactive ALDH2 was not associated with increased EC risk [HRs (95% CIs): GA vs. GG 0.75 (0.54, 1.04); AA vs. GG 1.01 (0.46, 2.20)]. Among male weekly alcohol consumers, both flushing response [n = 59,380; 501 EC cases; HRs (95% CIs): “soon after drinking” vs. “no” flushing response 1.45 (1.05, 2.01)] and rs671 [n = 10,692; 94 EC cases; GA vs. GG 3.31 (1.94, 5.67)] were associated with EC risk. The increased EC risk associated with “soon” response or rs671 GA was apparent in men consuming alcohol ≥30g/d. Among male daily consumers, the HRs (95% CIs) for EC associated with 15g/d of alcohol were 1.28 (1.15, 1.44) for “soon” response [vs. other responses: 1.12 (1.09, 1.15); p interaction = 0.047; n = 36,401, 425 EC cases] and 1.41 (1.08, 1.82) for rs671 GA [vs. GG: 1.16 (1.06, 1.27); p interaction = 0.493; n = 6,607, 80 EC cases]. Self‐reported flushing response had low sensitivity (56.8%) and high specificity (88.4%) in identifying rs671 A allele among male weekly alcohol consumers. In conclusion, low‐activity ALDH2 was associated with increased EC risk among male heavy alcohol consumers. More accurate measurement of alcohol‐related EC risk allows better achievement of precision prevention.

Type-2 diabetic aldehyde dehydrogenase 2 mutant mice (ALDH 2*2) exhibiting heart failure with preserved ejection fraction phenotype can be determined by exercise stress echocardiography.

E487K point mutation of aldehyde dehydrogenase (ALDH) 2 (ALDH2*2) in East Asians intrinsically lowers ALDH2 activity. ALDH2*2 is associated with diabetic cardiomyopathy. Diabetic patients exhibit heart failure of preserved ejection fraction (HFpEF) i.e. while the systolic heart function is preserved in them, they may exhibit diastolic dysfunction, implying a jeopardized myocardial health. Currently, it is challenging to detect cardiac functional deterioration in diabetic mice. Stress echocardiography (echo) in the clinical set-up is a procedure used to measure cardiac reserve and impaired cardiac function in coronary artery diseases. Therefore, we hypothesized that high-fat diet fed type-2 diabetic ALDH2*2 mutant mice exhibit HFpEF which can be measured by cardiac echo stress test methodology. We induced type-2 diabetes in 12-week-old male C57BL/6 and ALDH2*2 mice through a high-fat diet. At the end of 4 months of DM induction, we measured the cardiac function in diabetic and control mice of C57BL/6 and ALDH2*2 genotypes by conscious echo. Subsequently, we imposed exercise stress by allowing the mice to run on the treadmill until exhaustion. Post-stress, we measured their cardiac function again. Only after treadmill running, but not at rest, we found a significant decrease in % fractional shortening and % ejection fraction in ALDH2*2 mice with diabetes compared to C57BL/6 diabetic mice as well as non-diabetic (control) ALDH2*2 mice. The diabetic ALDH2*2 mice also exhibited poor maximal running speed and distance. Our data suggest that high-fat fed diabetic ALDH2*2 mice exhibit HFpEF and treadmill exercise stress echo test is able to determine this HFpEF in the diabetic ALDH2*2 mice.

Alda-1, an ALDH2 activator, protects against hepatic ischemia/reperfusion injury in rats via inhibition of oxidative stress

Previous studies have proved that activation of aldehyde dehydrogenase two (ALDH2) can attenuate oxidative stress through clearance of cytotoxic aldehydes, and can protect against cardiac, cerebral, and lung ischemia/reperfusion (I/R) injuries. In this study, we investigated the effects of the ALDH2 activator Alda-1 on hepatic I/R injury. Partial warm ischemia was performed in the left and middle hepatic lobes of Sprague-Dawley rats for 1 h, followed by 6 h of reperfusion. Rats received either Alda-1 or vehicle by intravenous injection 30 min before ischemia. Blood and tissue samples of the rats were collected after 6-h reperfusion. Histological injury, proinflammatory cytokines, reactive oxygen species (ROS), cellular apoptosis, ALDH2 expression and activity, 4-hydroxy-trans-2-nonenal (4-HNE) and malondialdehyde (MDA) were measured. BRL-3A hepatocytes were subjected to hypoxia/reoxygenation (H/R). Cell viability, ROS, and mitochondrial membrane potential were determined. Pretreatment with Alda-1 significantly alleviated I/R-induced elevations of alanine aminotransferase and aspartate amino transferase, and significantly blunted the pathological injury of the liver. Moreover, Alda-1 significantly inhibited ROS and proinflammatory cytokines production, 4-HNE and MDA accumulation, and apoptosis. Increased ALDH2 activity was found after Alda-1 administration. No significant changes in ALDH2 expression were observed after I/R. ROS was also higher in H/R cells than in control cells, which was aggravated upon treatment with 4-HNE, and reduced by Alda-1 treatment. Cell viability and mitochondrial membrane potential were inhibited in H/R cells, which was attenuated upon Alda-1 treatment. Activation of ALDH2 by Alda-1 attenuates hepatic I/R injury via clearance of cytotoxic aldehydes.

Endometriosis‐associated vaginal hyperalgesia is mediated by the balance of reactive aldehyde production and metabolism.

BackgroundEndometriosis affects ~176 million women worldwide and is characterized by the growth of endometrial tissue outside the uterus (known as endometrial ectopic cysts). How endometriosis becomes associated with painful symptoms is not clear. Here we hypothesize that endometriosis‐associated vaginal hyperalgesia is mediated by an imbalance of reactive aldehyde production and metabolism.MethodsTo test this hypothesis, we used female Sprague‐Dawley rats (n=5/group) and subjected them to a cutting‐edge model of behavioral psychophysics to assess for rat vaginal nociception. Prior to subjecting the rodents to this model, we treated rodents with the reactive aldehyde, acetaldehyde (9 mg/kg intraperitoneal) to mimic an increased production of reactive aldehydes in the intraperitoneal space. To modulate ALDH2 activity, we administered to rodents either the ALDH2 activator, Alda‐1 (1 mg/kg, diluted in DMSO, given intraperitoneal) or the ALDH2 inhibitor disulfiram (15 mg/kg, diluted in DMSO, given intraperitoneal). The ALDH2 activator were delivered 10 minutes before or after acetaldehyde (Alda‐1 + aldehyde or aldehyde +Alda‐1). Disulfiram was given 10 minutes before acetaldehyde (Disulfiram + aldehyde). As controls Alda‐1, disulfiram, saline, and DMSO were delivered alone. Changes in vaginal nociception were expressed as area‐under‐the‐curve (AUC) units and calculated using standard trapezoid methods. For statistical analysis, a one‐way ANOVA with Bonferroni's multiple comparison test was used. Data presented as mean ± SEM.ResultsAcetaldehyde‐induced vaginal hyperalgesia (44±4* vs. saline 28±2, *P&lt;0.05). Alda‐1 markedly attenuated hyperalgesia when given either before (26±3, *P&lt;0.05 vs. acetaldehyde) or after (25±3, *P&lt;0.05 vs. acetaldehyde) acetaldehyde treatment. Conversely, pretreatment with disulfiram before acetaldehyde increased vaginal hyperalgesia (61±5, *P&lt;0.05 vs. acetaldehyde). Alda‐1, DMSO, and disulfiram alone produced no significant changes in vaginal nociception.ConclusionsThese data suggest that the mechanism of endometriosis‐induced hyperalgesia is mediated by changes in reactive aldehyde production and metabolism. Increasing ALDH2 activity in rats, both prevented and alleviated reactive aldehyde‐induced vaginal hyperalgesia. These data suggest a potential novel therapeutic for treating endometriosis by targeting reactive aldehyde metabolism.Support or Funding InformationThis work was supported by the National Institutes of Child Health and Human Development K99HD093858 (SLM), a Stanford Women &amp; Sex Differences in Medicine (WSDM) Seed Grant, and an Endometriosis Foundation of America Research Award.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

E‐cigarette vapor elevates heart rate in mice with limited reactive aldehyde metabolism

BackgroundE‐cigarettes contain high levels of reactive aldehydes including acrolein, acetaldehyde and formaldehyde in addition to nicotine. However, the cardiovascular effects of e‐cigarette exposure are not well studied. Furthermore, ~560 million people of East Asian descent cannot efficiently metabolize these aldehydes in e‐cigarettes due to a genetic variant in aldehyde dehydrogenase 2, known as ALDH2*2. Therefore, we tested our hypothesis that e‐cigarette vapor exposure alters heart rates in wild type ALDH2 mice and these effects are exacerbated in ALDH2*2 knock‐in mice.MethodsTo test our hypothesis, both male and female wild type and homozygote ALDH2*2 mice (8–12 weeks old) were implanted with a mouse Biopotential Telemeter (Millar) and heart rate was acquired with LabChart 8 (AD Instruments) (n = 4/genotype). All mice were exposed to 60 puffs (5 sec duration and 60 ml puff volume) a day for 5 days. With each e‐cigarette exposure, we also monitored the reactive aldehyde levels in e‐cigarette vapor in real‐time by selective ion flow mass spectrometry. Furthermore, ALDH2 expression and activity in whole heart mitochondrial fractions were determined by biochemical assays (n= 3/genotype). Statistical analysis was performed using Graph Pad Prism 6.0. Data are expressed as mean ± SEM. Student's t‐test was used for comparison between two groups and ANOVA followed by Bonferroni correction was used for multiple variant comparisons (* indicating P value &lt;0.001).ResultsWhen compared to baseline heart rates for wild type and ALDH2*2 mice, e‐cigarette vapor exposure leads to a substantial drop in heart rate for both wild type (739 ± 6 vs. 502 ± 36* bpm, respectively) and ALDH2*2 mice (712 ± 5 vs. 500 ± 43* bpm, respectively). Additionally, 5 days of continuous e‐cigarette exposure increased the resting heart rate by 49 ± 9* bpm in wild type and 163 ± 9* bpm in ALDH2*2 mice respectively. Quantification of reactive aldehyde levels in e‐cigarettes revealed that e‐cigarette vapor contained high levels of acetaldehyde (1506 ± 179.1* ppb), acrolein (38.2 ± 4.7* ppb) and formaldehyde (52.7 ± 3.7* ppb) in contrast to ambient air (acetaldehyde 35.5 ± 4.6 ppb, acrolein 8.5 ± 1.3 ppb, and formaldehyde 7.1 ± 0.3 ppb). Furthermore, compared to wild type mice, both heart ALDH2 expression (1.3 ± 0.2 vs. 0.5 ± 0.04* ADU) and activity (3 ± 0.2 vs. 1.1 ± 0.07* μmol/min/mg) were markedly lower in ALDH2*2 mice.ConclusionTogether, these findings suggest that e‐cigarette vapor exposure triggers changes in heart rate that is more pronounced in ALDH2*2 mice. Moreover, e‐cigarettes contain reactive aldehydes, including high levels of acetaldehyde. Therefore, e‐cigarette smoking/exposure may increase the risk of developing cardiovascular disease in individuals with ALDH2*2 variant.Support or Funding InformationTobacco‐Related Disease Research Program, California, United States.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The impact of ALDH2 activation by Alda-1 on the expression of VEGF in the hippocampus of a rat model of post-MI depression

Post-MI depression is a critical clinical problem, the comorbidity of which complicates depression treatment and worsens cardiovascular outcomes. However, which antidepressant is the best to lower the risk of cardiovascular events in persons with depression was still unknown. Recently, it has been proposed that the activation of ALDH2 by Alda-1 can effectively reduce depressive-like behaviors and improve the prognosis of coronary heart disease. In the present study, we investigated the effect of Alda-1 on the expression of VEGF in the hippocampus of a rat model with post-MI depression, as well as the potential treatment mechanism. Alda-1 administration significantly decreased the immobility time and increased the swimming time of the post-MI depression rats in the forced swim test. Moreover, treatment of post-MI depression rats with Alda-1 significantly increased the sucrose preference ratio, as assessed by a sucrose preference test. These behaviors were associated with an increase 5-HT and DA neurotransmitter content, as well as an increase of VEGF levels in the hippocampus of the post-MI depression rats. These results suggest that Alda-1 improves depressive-like behavior in rats after MI by increasing VEGF expression in the hippocampus of rats.

ALDH2 protects against high fat diet-induced obesity cardiomyopathy and defective autophagy: role of CaM kinase II, histone H3K9 methyltransferase SUV39H, Sirt1, and PGC-1α deacetylation.

Uncorrected obesity contributes to cardiac remodeling and contractile dysfunction although the underlying mechanism remains poorly understood. Mitochondrial aldehyde dehydrogenase (ALDH2) is a mitochondrial enzyme with some promises in a number of cardiovascular diseases. This study was designed to evaluate the impact of ALDH2 on cardiac remodeling and contractile property in high fat diet-induced obesity. Wild-type (WT) and ALDH2 transgenic mice were fed low (10% calorie from fat) or high (45% calorie from fat) fat diet for 5 months prior to the assessment of cardiac geometry and function using echocardiography, IonOptix system, Lectin, and Masson Trichrome staining. Western blot analysis was employed to evaluate autophagy, CaM kinase II, PGC-1α, histone H3K9 methyltransferase SUV39H, and Sirt-1. Our data revealed that high fat diet intake promoted weight gain, cardiac remodeling (hypertrophy and interstitial fibrosis, p < 0.0001) and contractile dysfunction (reduced fractional shortening (p < 0.0001), cardiomyocyte function (p < 0.0001), and intracellular Ca2+ handling (p = 0.0346)), mitochondrial injury (elevated O2- levels, suppressed PGC-1α, and enhanced PGC-1α acetylation, p < 0.0001), elevated SUV39H, suppressed Sirt1, autophagy and phosphorylation of AMPK and CaM kinase II, the effects of which were negated by ALDH2 (p ≤ 0.0162). In vitro incubation of the ALDH2 activator Alda-1 rescued against palmitic acid-induced changes in cardiomyocyte function, the effect of which was nullified by the Sirt-1 inhibitor nicotinamide and the CaM kinase II inhibitor KN-93 (p < 0.0001). The SUV39H inhibitor chaetocin mimicked Alda-1-induced protection again palmitic acid (p < 0.0001). Examination in overweight human revealed an inverse correlation between diastolic cardiac function and ALDH2 gene mutation (p < 0.05). Taken together, these data suggest that ALDH2 serves as an indispensable factor against cardiac anomalies in diet-induced obesity through a mechanism related to autophagy regulation and facilitation of the SUV39H-Sirt1-dependent PGC-1α deacetylation.