Alcoholic cardiomyopathy: acetaldehyde, insulin insensitization and ER stress

Astaxanthin treatment ameliorates ER stress in polycystic ovary syndrome patients: a randomized clinical trial

Astaxanthin (ASX), as a natural carotenoid compound, exists in various types of seafood and microorganisms. It has several possible beneficial therapeutic effects for patients with polycystic ovary syndrome (PCOS). Patients with PCOS also suffer from endoplasmic reticulum (ER) stress. In the present work, it was hypothesized that ER stress could be improved by ASX in PCOS patients. Granulosa cells (GCs) were obtained from 58 PCOS patients. The patients were classified into ASX treatment (receiving 12 mg/day for 60 days) and placebo groups. The expression levels of ER stress pathway genes and proteins were explored using Western blotting and quantitative polymerase chain reaction. To assess oxidative stress markers, follicular fluid (FF) was gained from all patients. The Student's t test was used to perform statistical analysis. After the intervention, ASX led to a considerable reduction in the expression levels of 78-kDa glucose-regulated protein (GRP78), CCAAT/enhancer-binding protein homologous protein (CHOP), and X-box-binding protein 1 compared to the placebo group, though the reduction in the messenger RNA (mRNA) expression level of activating transcription factor 6 was not statistically significant. However, ASX significantly increased the ATF4 expression level. GRP78 and CHOP protein levels represented a considerable decrease in the treatment group after the intervention. In addition, a statistically significant increase was found in the FF level of total antioxidant capacity in the treatment group. Based on clinical outcomes, no significant differences were found between the groups in terms of the oocyte number, fertilization rate, and fertility rate, but the ASX group had higher rates of high-quality oocytes, high-quality embryo, and oocyte maturity compared to the placebo group. Our findings demonstrated that ER stress in the GCs of PCOS patients could be modulated by ASX by changing the expression of genes and proteins included in the unfolding protein response.Trial registration This study was retrospectively registered on the Iranian Registry of Clinical Trials website ( www.irct.ir ; IRCT-ID: IRCT20201029049183N, 2020-11-27).

Astaxanthin attenuates alcoholic cardiomyopathy via inhibition of endoplasmic reticulum stress-mediated cardiac apoptosis

Chronic excessive ethanol consumption is associated with a high incidence of mortality due to ethanol-induced dilated cardiomyopathy, known as alcoholic cardiomyopathy (ACM). Mechanistic studies have demonstrated that apoptosis is key to the pathogenesis of ACM, and endoplasmic reticulum (ER) stress-associated apoptosis contributes to various ethanol-related diseases. Astaxanthin (AST) is a natural carotenoid that exerts an anti-ER stress effect. Importantly, strong evidence has shown that AST induces beneficial effects in various cardiovascular diseases. The present study aimed to investigate whether AST induces beneficial effects on ACM by suppressing cardiac apoptosis mediated by ER stress. We showed that after 2 months of chronic excessive ethanol consumption, mice displayed obvious cardiac dysfunction and morphological changes associated with increased fibrosis, oxidative stress, ER stress and apoptosis. However, cardiac damage above was attenuated in response to AST treatment. The cardioprotective effect of AST against ethanol toxicity was also confirmed in both H9c2 cells and primary cardiomyocytes, indicating that AST-induced protection directly targets cardiomyocytes. Both in vivo and in vitro studies showed that AST inhibited all three ER stress signaling pathways activated by ethanol. Furthermore, administration of the ER stress inhibitor sodium 4-phenylbutyrate (4-PBA) strongly suppressed ethanol-induced cardiomyocyte damage. Interestingly, AST induced further anti-apoptotic effects once co-treated with 4-PBA, indicating that AST protects the heart from ACM partially by attenuating ER stress, but other mechanisms still exist. This study highlights that administration of AST ablated chronic excessive ethanol consumption-induced cardiomyopathy by suppressing cardiac ER stress and subsequent apoptosis.

The Association between Alcohol Consumption and Serum Metabolites and the Modifying Effect of Smoking

Alcohol consumption is an important lifestyle factor that is associated with several health conditions and a behavioral link with smoking is well established. Metabolic alterations after alcohol consumption have yet to be comprehensively investigated. We studied the association of alcohol consumption with metabolite patterns (MPs) among 2433 individuals from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam Study, and a potential modification by smoking. Alcohol consumption was self-reported through dietary questionnaires and serum metabolites were measured by a targeted approach. The metabolites were summarized as MPs using the treelet transform analysis (TT). We fitted linear models with alcohol consumption continuously and in five categories. We stratified the continuously modelled alcohol consumption by smoking status. All models were adjusted for potential confounders. Among men, alcohol consumption was positively associated with six MPs and negatively associated with one MP. In women, alcohol consumption was inversely associated with one MP. Heavy consumers differed from other consumers with respect to the "Long and short chain acylcarnitines" MP. Our findings suggest that long and short chain acylcarnitines might play an important role in the adverse effects of heavy alcohol consumption on chronic diseases. The relations seem to depend on gender and smoking status.

SREBP1c mediates the effect of acetaldehyde on Cidea expression in Alcoholic fatty liver Mice

Cell death inducing DNA fragmentation factor-alpha-like A (Cidea) is a member of cell death-inducing DFF45-like effector (CIDE) protein. The initial function of CIDE is the promotion of cell death and DNA fragmentation in mammalian cells. Cidea was recently reported to play critical roles in the development of hepatic steatosis. The purpose of present study is to determine the effect of chronic alcohol intake on Cidea expression in the livers of mice with alcoholic fatty liver disease. Cidea expression was significantly increased in the liver of alcohol-induced fatty liver mice. While, knockdown of Cidea caused lipid droplets numbers reduction. Next, we detected the activity of ALDH2 reduction and the concentration of serum acetaldehyde accumulation in our alcohol-induced fatty liver mice. Cidea expression was elevated in AML12 cells exposed to 100uM acetaldehyde. Interestingly, Dual-luciferase reporter gene assay showed that 100 uM acetaldehyde led to the activation of Cidea reporter gene plasmid which containing SRE element. What’s more, the knockdown of SREBP1c suppressed acetaldehyde-induced Cidea expression. Overall, our findings suggest that Cidea is highly associated with alcoholic fatty liver disease and Cidea expression is specifically induced by acetaldehyde, and this up-regulation is most likely mediated by SREBP1c.

From the Cover: Alcohol Inhibition of the Enzymatic Activity of Glyceraldehyde 3-Phosphate Dehydrogenase Impairs Cardiac Glucose Utilization, Contributing to Alcoholic Cardiomyopathy

Heavy consumption of alcohol induces cardiomyopathy and is associated with metabolic changes in the heart. The role of altered metabolism in the development of alcoholic cardiomyopathy remains largely unknown but is examined in the present study. The effect of chronic alcohol consumption on cardiac damage was examined in mice fed an alcohol or isocaloric control diet for 2 months. Signaling pathways of alcohol-induced metabolic alteration and pathologic changes were examined in both animal hearts and H9c2 cell cultures. Compared with controls, the hearts from the alcohol-fed mice exhibited cardiac oxidative stress, cell death, a fibrotic response, hypertrophic remodeling, and the eventual development of cardiac dysfunction. All these detrimental effects could be ameliorated by superoxide dismutase mimic Mn (111) tetrakis 1-methyl 4-pyridylporphyrin pentachloride (MnTMPyP) therapy. A mechanistic study showed that chronic alcohol exposure enhanced the expression of proteins regulating fatty acid uptake but impaired the expression of proteins involved in mitochondrial fatty acid oxidation, which compensatively geared the heart to the suboptimal energy source, glucose. However, chronic alcohol exposure also impaired the glycolytic energy production step regulated by glyceraldehyde-3-phosphate dehydrogenase, which further feeds back to enhance glucose uptake signaling and the accumulation of glycolytic intermediate product fructose, resulting in aggravation of alcohol-induced cardiac oxidative stress, cell death, and remodeling. All these dysmetabolic alterations could be normalized by MnTMPyP treatment, along with significant improvement in cardiac cell death and remodeling. These results demonstrate that alcohol-induced oxidative stress and altered glucose metabolism are causal factors for the development of alcoholic cardiomyopathy.

Protective effects of dioscin against alcohol-induced liver injury

Our previous studies have shown that dioscin has protective effect against liver injury. However, the action of the compound against ethanol-induced liver injury is still unknown. In the present paper, ethanol-induced acute and chronic liver damage rat models were used, and the results showed that dioscin significantly alleviated liver steatosis, reduced the levels of alanine aminotransferase, aspartate aminotransferase, total triglyceride (TG), total cholesterol and malondialdehyde, and increased the levels of high-density lipoprotein, superoxide dismutase, glutathione and glutathione peroxidase. Transmission electron microscopy and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays showed that dioscin prevented mitochondrial ultrastructural alterations and apoptosis caused by ethanol. In addition, dioscin significantly inhibited ethanol-induced cytochrome P450 2E1 activation, down-regulated the levels of mitogen-activated protein kinases phosphorylation, inhibited the expressions of nuclear factor kappa B, glucose regulated protein 78, activating transcription factor 6 and alpha subunit of translation initiation factor 2 to attenuate oxidative damage, decreased the expressions of tumor necrosis factor alpha and interleukin-6, and down-regulated the expressions of apoptosis-related proteins including p53, caspase-3, caspase-9, poly (ADP-ribose)-polymerase and cytokeratin-18. Further investigation indicated that dioscin markedly increased the expressions of peroxisome proliferators-activated receptor α and its target genes including medium-chain acyl-CoA dehydrogenase, carnitine palmitoyl-CoA transferase I and acyl-CoA oxidase to advance fatty acid β-oxidation, up-regulated the expressions of acyl-CoA synthetase long-chain family member 1, acyl-CoA synthetase long-chain family member 5, alpha-aminoadipic semialdehyde dehydrogenase and acyl-CoA dehydrogenase to promote fatty acid metabolism, and down-regulated the expressions of glycerol-3-phosphate acyltransferase, diacylglycerol acyltransferase 1 and diacylglycerol acyltransferase 2 to accelerate TG synthesis. However, dioscin had no effects on the expressions of sterol regulatory element-binding protein-1c, fatty acid synthase, acetyl-CoA carboxylase 1 and stearoyl-CoA desaturase 1 associated with fatty acid synthesis. In conclusion, dioscin shows excellent protective effect against ethanol-induced liver injury through ameliorating ethanol-induced oxidative stress, mitochondrial function, inflammatory cytokine production, apoptosis and liver steatosis, which should be developed as a new drug for the treatment of ethanol-induced liver injury in the future.

Mitochondria as a source and target of lipid peroxidation products in healthy and diseased heart

The heart is a highly oxidative organ in which cardiomyocyte turnover is virtually absent, making it particularly vulnerable to accumulation of lipid peroxidation products (LPP) formed as a result of oxidative damage. Reactive oxygen and nitrogen species are the most common electrophiles formed during lipid peroxidation and lead to the formation of both stable and unstable LPP. Of the LPP formed, highly reactive aldehydes are a well-recognized causative factor in ageing and age-associated diseases, including cardiovascular disease and diabetes. Recent studies have identified that the mitochondria are both a primary source and target of LPP, with specific emphasis on aldehydes in cardiomyocytes and how these affect the electron transport system and Ca(2+) balance. Numerous studies have found that there are functional consequences in the heart following exposure to specific aldehydes (acrolein, trans-2-hexanal, 4-hydroxynonenal and acetaldehyde). Because these LPP are known to form in heart failure, cardiac ischaemia-reperfusion injury and diabetes, they may have an underappreciated role in the pathophysiology of these disease processes. Lipid peroxidation products are involved in the transcriptional regulation of endogenous anti-oxidant systems. Recent evidence demonstrates that transient increases in LPP may be beneficial in cardioprotection by contributing to mitohormesis (i.e. induction of anti-oxidant systems) in cardiomyocytes. Thus, exploitation of the cardioprotective actions of the LPP may represent a novel therapeutic strategy for future treatment of heart disease.

Facilitated ethanol metabolism promotes cardiomyocyte contractile dysfunction through autophagy in murine hearts

Chronic drinking leads to myocardial contractile dysfunction where ethanol metabolism plays an essential role. Acetaldehyde, the main ethanol metabolite, mediates alcohol-induced cell injury although the underlying mechanism is still elusive. This study was designed to examine the mechanism involved in accelerated ethanol metabolism-induced cardiac defect with a focus on autophagy. Wild-type FVB and cardiac-specific overexpression of alcohol dehydrogenase mice were placed on a 4% nutrition-balanced alcohol diet for 8 weeks. Myocardial histology, immunohistochemistry, autophagy markers and signal molecules were examined. Expression of micro RNA miR-30a, a potential target of Beclin 1, was evaluated by real-time PCR. Chronic alcohol intake led to cardiac acetaldehyde accumulation, hypertrophy and overt autophagosome accumulation (LC3-II and Atg7), the effect of which was accentuated by ADH. Signaling molecules governing autophagy initiation including class III PtdIns3K, phosphorylation of mTOR and p70S6K were enhanced and dampened, respectively, following alcohol intake. These alcohol-induced signaling responses were augmented by ADH. ADH accentuated or unmasked alcohol-induced downregulation of Bcl-2, Bcl-xL and MiR-30a. Interestingly, ADH aggravated alcohol-induced p62 accumulation. Autophagy inhibition using 3-MA abolished alcohol-induced cardiomyocyte contractile anomalies. Moreover, acetaldehyde led to cardiomyocyte contractile dysfunction and autophagy induction, which was ablated by 3-MA. Ethanol or acetaldehyde increased GFP-LC3 puncta in H9c2 cells, the effect of which was ablated by 3-MA but unaffected by lysosomal inhibition using bafilomycin A(1), E64D and pepstatin A. In summary, these data suggested that facilitated acetaldehyde production via ADH following alcohol intake triggered cardiac autophagosome formation along with impaired lysosomal degradation, en route to myocardial defect.

Mitochondria and Oxidative Stress in the Cardiorenal Metabolic Syndrome

Mitochondria play a fundamental role in the maintenance of normal structure, function, and survival of tissues. There is considerable evidence for mitochondrial dysfunction in association with metabolic diseases including insulin resistance, obesity, diabetes, and the cardiorenal metabolic syndrome. The phenomenon of reactive oxygen species (ROS)-induced ROS release through interactions between cytosolic and mitochondrial oxidative stress contributes to a vicious cycle of enhanced oxidative stress and mitochondrial dysfunction. Activation of the cytosolic and mitochondrial NADPH oxidase system, impairment of the mitochondrial electron transport, activation of p66shc pathway-targeting mitochondria, endoplasmic reticular stress, and activation of the mammalian target of the rapamycin-S6 kinase pathway underlie dysregulation of mitochondrial dynamics and promote mitochondrial oxidative stress. These processes are further modulated by acetyltransferases including sirtuin 1 and sirtuin 3, the former regulating nuclear acetylation and the latter regulating mitochondrial acetylation. The regulation of mitochondrial functions by microRNAs forms an additional layer of molecular control of mitochondrial oxidative stress. Alcohol further exacerbates mitochondrial oxidative stress induced by overnutrition and promotes the development of metabolic diseases.

ALDH2 in alcoholic heart diseases: molecular mechanism and clinical implications

Alcoholic cardiomyopathy is manifested as cardiac hypertrophy, disrupted contractile function and myofibrillary architecture. An ample amount of clinical and experimental evidence has depicted a pivotal role for alcohol metabolism especially the main alcohol metabolic product acetaldehyde, in the pathogenesis of this myopathic state. Findings from our group and others have revealed that the mitochondrial isoform of aldehyde dehydrogenase (ALDH2), which metabolizes acetaldehyde, governs the detoxification of acetaldehyde formed following alcohol consumption and the ultimate elimination of alcohol from the body. The ALDH2 enzymatic cascade may evolve as a unique detoxification mechanism for environmental alcohols and aldehydes to alleviate the undesired cardiac anomalies in ischemia-reperfusion and alcoholism. Polymorphic variants of the ALDH2 gene encode enzymes with altered pharmacokinetic properties and a significantly higher prevalence of cardiovascular diseases associated with alcoholism. The pathophysiological effects of ALDH2 polymorphism may be mediated by accumulation of acetaldehyde and other reactive aldehydes. Inheritance of the inactive ALDH2*2 gene product is associated with a decreased risk of alcoholism but an increased risk of alcoholic complications. This association is influenced by gene-environment interactions such as those associated with religion and national origin. The purpose of this review is to recapitulate the pathogenesis of alcoholic cardiomyopathy with a special focus on ALDH2 enzymatic metabolism. It will be important to dissect the links between ALDH2 polymorphism and prevalence of alcoholic cardiomyopathy, in order to determine the mechanisms underlying such associations. The therapeutic value of ALDH2 as both target and tool in the management of alcoholic tissue damage will be discussed.

Mitochondria-targeted cardioprotection in aldosteronism

Chronic aldosterone/salt treatment (ALDOST) is accompanied by an adverse structural remodeling of myocardium that includes multiple foci of microscopic scarring representing morphologic footprints of cardiomyocyte necrosis. Our previous studies suggested that signal-transducer-effector pathway leading to necrotic cell death during ALDOST includes intramitochondrial Ca overloading, together with an induction of oxidative stress and opening of the mitochondrial permeability transition pore (mPTP). To further validate this concept, we hypothesized that mitochondria-targeted interventions will prove to be cardioprotective. Accordingly, 8-week-old male Sprague-Dawley rats receiving 4 weeks ALDOST were cotreated with either quercetin, a flavonoid with mitochondrial antioxidant properties, or cyclosporine A (CsA), an mPTP inhibitor, and compared with ALDOST alone or untreated, age/sex-matched controls. We monitored mitochondrial free Ca and biomarkers of oxidative stress, including 8-isoprostane and H2O2 production; mPTP opening; total Ca in cardiac tissue; and collagen volume fraction to quantify replacement fibrosis, a biomarker of cardiomyocyte necrosis, and employed terminal deoxynucleotidyl transferase dUTP nick end labeling assay to address apoptosis in coronal sections of ventricular myocardium. Compared with controls, at 4 weeks ALDOST we found a marked increase in mitochondrial H2O2 production and 8-isoprostane levels, an increased propensity for mPTP opening, and greater concentrations of mitochondrial free [Ca]m and total tissue Ca, coupled with a 5-fold rise in collagen volume fraction without any terminal deoxynucleotidyl transferase dUTP nick end labeling-based evidence of cardiomyocyte apoptosis. Each of these pathophysiologic responses to ALDOST was prevented by quercetin or cyclosporine A cotreatment. Thus, mitochondria play a central role in initiating the cellular-subcellular mechanisms that lead to necrotic cell death and myocardial scarring. This destructive cycle can be interrupted and myocardium salvaged with its structure preserved by mitochondria-targeted cardioprotective strategies.

Acetaldehyde adducts in alcoholic liver disease

Chronic alcohol abuse causes liver disease that progresses from simple steatosis through stages of steatohepatitis, fibrosis, cirrhosis, and eventually hepatic failure. In addition, chronic alcoholic liver disease (ALD), with or without cirrhosis, increases risk for hepatocellular carcinoma (HCC). Acetaldehyde, a major toxic metabolite, is one of the principal culprits mediating fibrogenic and mutagenic effects of alcohol in the liver. Mechanistically, acetaldehyde promotes adduct formation, leading to functional impairments of key proteins, including enzymes, as well as DNA damage, which promotes mutagenesis. Why certain individuals who heavily abuse alcohol, develop HCC (7.2-15%) versus cirrhosis (15-20%) is not known, but genetics and co-existing viral infection are considered pathogenic factors. Moreover, adverse effects of acetaldehyde on the cardiovascular system and hematologic systems leading to ischemia, heart failure, and coagulation disorders, can exacerbate hepatic injury and increase risk for liver failure. Herein, we review the role of acetaldehyde adducts in the pathogenesis of chronic ALD and HCC.

Diabetes- and angiotensin II-induced cardiac endoplasmic reticulum stress and cell death: metallothionein protection

We have shown cardiac protection by metallothionein (MT) in the development of diabetic cardiomyopathy (DCM) via suppression of cardiac cell death in cardiac-specific MT-overexpressing transgenic (MT-TG) mice. The present study was undertaken to define whether diabetes can induce cardiac endoplasmic reticulum (ER) stress and whether MT can prevent cardiac cell death via attenuating ER stress. Diabetes was induced by streptozotocin in both MT-TG and wild-type (WT) mice. Two weeks, and 2 and 5 months after diabetes onset, cardiac ER stress was detected by expression of ER chaperones, and apoptosis was detected by CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) and cleaved caspase-3 and caspase-12. Cardiac apoptosis in the WT diabetic mice, but not in MT-TG diabetic mice, was significantly increased 2 weeks after diabetes onset. In parallel with apoptotic effect, significant up-regulation of the ER chaperones, including glucose-regulated protein (GRP)78 and GRP94, cleaved ATF6 and phosporylated eIF2alpha, in the hearts of WT, but not MT-TG diabetic mice. Infusion of angiotensin II (Ang II) also significantly induced ER stress and apoptosis in the hearts of WT, but not in MT-TG mice. Direct administration of chemical ER stress activator tunicamycin significantly increased cardiac cell death only in WT mice. Pre-treatment with antioxidants completely prevented Ang II-induced ER stress and apoptosis in the cultured cardiac cells. These results suggest that ER stress exists in the diabetic heart, which may cause the cardiac cell death. MT prevents both diabetes- and Ang II-induced cardiac ER stress and associated cell death most likely via its antioxidant action, which may be responsible for MT's prevention of DCM.

Chronic ethanol consumption resulting in the downregulation of insulin receptor-beta subunit, insulin receptor substrate-1, and glucose transporter 4 expression in rat cardiac muscles

The objective of this study was to investigate the effect of chronic ethanol intake on the expression of insulin receptor beta subunit (IR-beta), insulin receptor substrate-1 (IRS-1), and glucose transporter 4 (Glut4) in rat cardiac muscle. Forty-eight male Wistar rats were randomly classified into four groups and to each group, ethanol was administered daily at the respective doses of 0 (control, C), 0.5 g kg(-1) (low ethanol, L), 2.5 g kg(-1) (middle ethanol, M), and 5 g kg(-1) (high ethanol, H). Twenty-two weeks later, the rats were anesthetized, and the left ventricle muscles were excised. The IR-beta, IRS-1, and Glut4 mRNA levels in the cardiac muscle tissues were detected by reverse-transcription polymerase chain reaction (RT-PCR); the IR-beta, tyrosine phosphorylation of IR-beta (PY-IR-beta), IRS-1, tyrosine phosphorylation of IRS-1 (PY-IRS-1), and Glut4 protein levels were measured by Western blotting. Compared to the control group, the IR-beta, IRS-1, and Glut4 mRNA levels in groups H and M decreased remarkably. In addition, the protein levels of IR-beta, IRS-1, and Glut4 showed a corresponding decline in ethanol-treated groups, especially in group H. Moreover, the PY-IR-beta and PY-IRS-1 protein levels decreased in the hearts of ethanol-treated rats with corresponding changes in the IR-beta and IRS-1 protein levels. The present study showed that chronic ethanol intake could downregulate the expression levels of IR-beta, IRS-1, and Glut4 in rat cardiac muscles.