Carbonylation of Runx2 at K176 by 4-Hydroxynonenal Accelerates Vascular Calcification.

BACKGROUND: Vascular calcification, which is characterized by calcium deposition in arterial walls and the osteochondrogenic differentiation of vascular smooth muscle cells, is an actively regulated process that involves complex mechanisms. Vascular calcification is associated with increased cardiovascular adverse events. The role of 4-hydroxynonenal (4-HNE), which is the most abundant stable product of lipid peroxidation, in vascular calcification has been poorly investigated. METHODS: Serum was collected from patients with chronic kidney disease and controls, and the levels of 4-HNE and 8-iso-prostaglandin F2α were measured. Sections of coronary atherosclerotic plaques from donors were immunostained to analyze calcium deposition and 4-HNE. A total of 658 patients with coronary artery disease who received coronary computed tomography angiography were recruited to analyze the relationship between coronary calcification and the rs671 mutation in aldehyde dehydrogenase 2 (ALDH2). ALDH2 knockout (ALDH2-/-) mice, smooth muscle cell-specific ALDH2 knockout mice, ALDH2 transgenic mice, and their controls were used to establish vascular calcification models. Primary mouse aortic smooth muscle cells and human aortic smooth muscle cells were exposed to medium containing ß-glycerophosphate and CaCl2 to investigate cell calcification and the underlying molecular mechanisms. RESULTS: Elevated 4-HNE levels were observed in the serum of patients with chronic kidney disease and model mice and were detected in calcified artery sections by immunostaining. ALDH2 knockout or smooth muscle cell-specific ALDH2 knockout accelerated the development of vascular calcification in model mice, whereas overexpression or activation prevented mouse vascular calcification and the osteochondrogenic differentiation of vascular smooth muscle cells. In patients with coronary artery disease, patients with ALDH2 rs671 gene mutation developed more severe coronary calcification. 4-HNE promoted calcification of both mouse aortic smooth muscle cells and human aortic smooth muscle cells and their osteochondrogenic differentiation in vitro. 4-HNE increased the level of Runx2 (runt-related transcription factor-2), and the effect of 4-HNE on promoting vascular smooth muscle cell calcification was ablated when Runx2 was knocked down. Mutation of Runx2 at lysine 176 reduced its carbonylation and eliminated the 4-HNE-induced upregulation of Runx2. CONCLUSIONS: Our results suggest that 4-HNE increases Runx2 stabilization by directly carbonylating its K176 site and promotes vascular calcification. ALDH2 might be a potential target for the treatment of vascular calcification.

The role of periostin in cardiac fibrosis.

Cardiac fibrosis, which is the buildup of proteins in the connective tissues of the heart, can lead to end-stage extracellular matrix (ECM) remodeling and ultimately heart failure. Cardiac remodeling involves changes in gene expression in cardiac cells and ECM, which significantly leads to the morbidity and mortality in heart failure. However, despite extensive research, the elusive intricacies underlying cardiac fibrosis remain unidentified. Periostin, an extracellular matrix (ECM) protein of the fasciclin superfamily, acts as a scaffold for building complex architectures in the ECM, which improves intermolecular interactions and augments the mechanical properties of connective tissues. Recent research has shown that periostin not only contributes to normal ECM homeostasis in a healthy heart but also serves as a potent inducible regulator of cellular reorganization in cardiac fibrosis. Here, we reviewed the constitutive domain of periostin and its interaction with other ECM proteins. We have also discussed the critical pathophysiological functions of periostin in cardiac remodeling mechanisms, including two distinct yet potentially intertwined mechanisms. Furthermore, we will focus on the intrinsic complexities within periostin research, particularly surrounding the contentious issues observed in experimental findings.

Adenosine kinase protects against acetaminophen-induced acute liver injury by activating autophagy in hepatocytes.

Acute liver injury (ALI) is a common life-threatening condition with a high mortality rate due to liver disease-related death. However, current therapeutic interventions for ALI remain ineffective, and the development of effective novel therapies is urgently needed. Liver samples from patients with drug-induced ALI were collected to detect adenosine kinase (ADK) expression. Male C57BL/6 J mice, hepatocyte-specific ADK knockout (ADKHKO) mice, and their controls (ADKf/f) were exposed to acetaminophen (APAP) and other treatments to investigate the mechanisms of APAP-related ALI. ADK expression was significantly decreased in APAP-injured livers. Hepatocyte-specific ADK deficiency exacerbated APAP-induced ALI, while a gain-of-function approach delivering AAV-ADK, markedly alleviated APAP-induced ALI, as indicated by changes in alanine aminotransferases (ALT) levels, aspartate aminotransferase (AST) levels, neutrophil infiltration and hepatocyte death. This study showed that ADK played a critical role in ALI by activating autophagy through two signaling pathways, the adenosine monophosphate-activated protein kinase (AMPK)-mTOR pathway and the adenosine receptor A1 (ADORA1)-Akt-mTOR pathway. Furthermore, we found that metformin upregulated ADK expression in hepatocytes and protected against APAP-induced ALI. These results demonstrate that ADK is critical in protecting against APAP-induced ALI and that developing therapeutics targeting ADK-adenosine-ADORA1 is a new approach for ALI treatment. Metformin is a potential candidate for preventing ALI by upregulating ADK.

Macrophage ALDH2 (Aldehyde Dehydrogenase 2) Stabilizing Rac2 Is Required for Efferocytosis Internalization and Reduction of Atherosclerosis Development.

BACKGROUND: Clinical studies show that the most common single-point mutation in humans, ALDH2 (aldehyde dehydrogenase 2) rs671 mutation, is a risk factor for the development and poor prognosis of atherosclerotic cardiovascular diseases, but the underlying mechanism remains unclear. Apoptotic cells are phagocytosed and eliminated by macrophage efferocytosis during atherosclerosis, and enhancement of arterial macrophage efferocytosis reduces atherosclerosis development. METHODS: Plaque areas, necrotic core size, apoptosis, and efferocytosis in aortic lesions were investigated in APOE-/- mice with bone marrow transplanted from APOE-/-ALDH2-/- and APOE-/- mice. RNA-seq, proteomics, and immunoprecipitation experiments were used to screen and validate signaling pathways affected by ALDH2. Efferocytosis and protein levels were verified in human macrophages from wild-type and rs671 mutation populations. RESULTS: We found that transplanting bone marrow from APOE-/-ALDH2-/- to APOE-/- mice significantly increased atherosclerosis plaques compared with transplanting bone marrow from APOE-/- to APOE-/- mice. In addition to defective efferocytosis in plaques of APOE-/- mice bone marrow transplanted from APOE-/-ALDH2-/- mice in vivo, macrophages from ALDH2-/- mice also showed significantly impaired efferocytotic activity in vitro. Subsequent RNA-seq, proteomics, and immunoprecipitation experiments showed that wild-type ALDH2 directly interacted with Rac2 and attenuated its degradation due to decreasing the K48-linked polyubiquitination of lysine 123 in Rac2, whereas the rs671 mutant markedly destabilized Rac2. Furthermore, Rac2 played a more crucial role than other Rho GTPases in the internalization process in which Rac2 was up-regulated, activated, and clustered into dots. Overexpression of wild-type ALDH2 in ALDH2-/- macrophages, rather than the rs671 mutant, rescued Rac2 degradation and defective efferocytosis. More importantly, ALDH2 rs671 in human macrophages dampened the apoptotic cells induced upregulation of Rac2 and subsequent efferocytosis. CONCLUSIONS: Our study has uncovered a pivotal role of the ALDH2-Rac2 axis in mediating efferocytosis during atherosclerosis, highlighting a potential therapeutic strategy in cardiovascular diseases, especially for ALDH2 rs671 mutation carriers.

Posttranslational modifications of platelet adhesion receptors.

Platelets play a key role in normal hemostasis, whereas pathological platelet adhesion is involved in various cardiovascular events. The underlying cause in cardiovascular events involves plaque rupture leading to subsequent platelet adhesion, activation, release, and eventual thrombosis. Traditional antithrombotic drugs often target the signal transduction process of platelet adhesion receptors by influencing the synthesis of some key molecules, and their effects are limited. Posttranslational modifications (PTMs) of platelet adhesion receptors increase the functional diversity of the receptors and affect platelet physiological and pathological processes. Antithrombotic drugs targeting PTMs of platelet adhesion receptors may represent a new therapeutic idea. In this review, various PTMs, including phosphorylation, glycosylation, ubiquitination, nitrosylation, methylation, lipidation, and proteolysis, of three platelet adhesion receptors, glycoprotein Ib-IX-V (GPIb-IX-V), glycoprotein VI (GPVI), and integrin αIIbß3, are reviewed. It is important to comprehensively understand the PTMs process of platelet adhesion receptors.

Short-term efficacy of angiotensin receptor-neprilysin inhibitor treatment in patients with ST-segment elevation myocardial infarction with reduced ejection fraction after primary percutaneous coronary intervention: a propensity score matching study.

BACKGROUND: Acute myocardial infarction (AMI) causes a series of pathophysiological changes, including myocardial necrosis, myocardial edema, and microvascular damage. These changes eventually lead to severe cardiovascular events, such as ventricular remodeling, heart failure, and papillary dysfunction. Impaired cardiac function after ST-segment elevation myocardial infarction (STEMI) often manifests as a decrease in left ventricular ejection fraction (LVEF). Clinical trials have shown that angiotensin receptor-neprilysin inhibitor (ARNI) treatment has the potential to improve LVEF in patients with STEMI after primary percutaneous coronary intervention (PPCI). OBJECTIVE: The purpose of this study was to evaluate the short-term efficacy of ARNI versus angiotensin-converting enzyme inhibitor (ACEI) treatment in patients with STEMI who exhibit reduced LVEF after PPCI. METHODS: A total of 169 patients with STEMI exhibiting post-PPCI LVEF below 50% who were orally treated with ARNI between December 2017 and August 2020 were selected as the experimental group. A total of 136 patients with STEMI exhibiting post-PPCI LVEF below 50% who were orally treated with an ACEI between January 2016 and August 2020 were selected as the control group. LVEF was measured using cardiac ultrasonography during hospitalization and 3 months after discharge. Linear and logistic regression analyses were performed to compare patient demographics and hospitalization variables to evaluate the risk factors for change and rate of improvement in LVEF. Propensity score matching (PSM) was used to account for confounding factors. RESULTS: After PSM, the study cohort consisted of 81 patients in the ARNI group and 123 in the ACEI group. After an average follow-up period of 3 months, no significant difference was noted in the LVEF improvement rate between the experimental and control groups (P = 0.475, 95% CI: -0.062 to 0.134). Multivariate logistic regression analysis also indicated no significant correlation between the change in LVEF and oral ARNI treatment in patients with STEMI exhibiting reduced LVEF after PPCI (P > 0.05). CONCLUSION: The short-term effect of ARNI treatment on the cardiac function of patients with STEMI and reduced LVEF after PPCI is not superior to that of ACEI treatment.

Mortality in cardiogenic shock patients receiving mechanical circulatory support: a network meta-analysis.

OBJECTIVE: Mechanical circulatory support (MCS) devices are widely used for cardiogenic shock (CS). This network meta-analysis aims to evaluate which MCS strategy offers advantages. METHODS: A systemic search of PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials was performed. Studies included double-blind, randomized controlled, and observational trials, with 30-day follow-ups. Paired independent researchers conducted the screening, data extraction, quality assessment, and consistency and heterogeneity assessment. RESULTS: We included 39 studies (1 report). No significant difference in 30-day mortality was noted between venoarterial extracorporeal membrane oxygenation (VA-ECMO) and VA-ECMO plus Impella, Impella, and medical therapy. According to the surface under the cumulative ranking curve, the optimal ranking of the interventions was surgical venting plus VA-ECMO, medical therapy, VA-ECMO plus Impella, intra-aortic balloon pump (IABP), Impella, Tandem Heart, VA-ECMO, and Impella plus IABP. Regarding in-hospital mortality and 30-day mortality, the forest plot showed low heterogeneity. The results of the node-splitting approach showed that direct and indirect comparisons had a relatively high consistency. CONCLUSIONS: IABP more effectively reduce the incidence of 30-day mortality compared with VA-ECMO and Impella for the treatment of CS.

LincRNA-p21 Upregulates Nuclear Orphan Receptor Nr4a2 and Aggravates Myocardial Ischemia/Reperfusion Injury via Targeting MiR-466i-5p.

Myocardial ischemia/reperfusion (I/R) injury can bring about more cardiomyocyte death and aggravate cardiac dysfunction, but its pathogenesis remains unclear. This study aimed to investigate the role of long intergenic noncoding RNA-p21 (LincRNA-p21) in myocardial I/R injury and its underlying mechanism. Mice were subjected to myocardial I/R injury by ligation and release of the left anterior descending artery, and HL-1 cardiomyocytes were treated with hydrogen peroxide. Infarct area, cardiac function, and cardiomyocyte apoptosis were determined. Consequently, LincRNA-p21 was found to significantly be elevated both in the reperfused hearts and H2O2-treated cardiomyocytes. Moreover, genetic inhibition of LincRNA-p21 brought about reduced infarct area and improved cardiac function in mice subjected to myocardial I/R injury. LincRNA-p21 knockdown was also demonstrated to inhibit cardiomyocyte apoptosis both in vivo and in vitro. Notably, LincRNA-p21 silencing increased the expression of microRNA-466i-5p (miR-466i-5p) and suppressed the expression of nuclear receptor subfamily 4 group A member 2 (Nr4a2). Mechanically, LincRNA-p21 downregulated and directly interacted with miR-466i-5p, while application of miR-466i-5p inhibitor promoted cardiomyocyte apoptosis that was improved by LincRNA-p21 inhibition. Furthermore, Nr4a2 upregulation caused by LincRNA-p21 overexpression was partially reversed by miR-466i-5p mimics. Thus, LincRNA-p21 positively regulated the expression of Nr4a2, through sponging miR-466i-5p, promoting cardiomyocyte apoptosis in myocardial I/R injury. The current study revealed a novel LincRNA-p21/miR-466i-5p/Nr4a2 pathway for myocardial I/R injury, indicating that LincRNA-p21 may serve as a potential target for future therapy.

Inhibition of adenosine kinase attenuates myocardial ischaemia/reperfusion injury.

Increased adenosine helps limit infarct size in ischaemia/reperfusion-injured hearts. In cardiomyocytes, 90% of adenosine is catalysed by adenosine kinase (ADK) and ADK inhibition leads to higher concentrations of both intracellular adenosine and extracellular adenosine. However, the role of ADK inhibition in myocardial ischaemia/reperfusion (I/R) injury remains less obvious. We explored the role of ADK inhibition in myocardial I/R injury using mouse left anterior ligation model. To inhibit ADK, the inhibitor ABT-702 was intraperitoneally injected or AAV9 (adeno-associated virus)-ADK-shRNA was introduced via tail vein injection. H9c2 cells were exposed to hypoxia/reoxygenation (H/R) to elucidate the underlying mechanisms. ADK was transiently increased after myocardial I/R injury. Pharmacological or genetic ADK inhibition reduced infarct size, improved cardiac function and prevented cell apoptosis and necroptosis in I/R-injured mouse hearts. In vitro, ADK inhibition also prevented cell apoptosis and cell necroptosis in H/R-treated H9c2 cells. Cleaved caspase-9, cleaved caspase-8, cleaved caspase-3, MLKL and the phosphorylation of MLKL and CaMKII were decreased by ADK inhibition in reperfusion-injured cardiomyocytes. X-linked inhibitor of apoptosis protein (XIAP), which is phosphorylated and stabilized via the adenosine receptors A2B and A1/Akt pathways, should play a central role in the effects of ADK inhibition on cell apoptosis and necroptosis. These data suggest that ADK plays an important role in myocardial I/R injury by regulating cell apoptosis and necroptosis.

Short- and Long-Term Prognosis of Intravascular Ultrasound-Versus Angiography-Guided Percutaneous Coronary Intervention: A Meta-Analysis Involving 24,783 Patients.

BACKGROUND: Intravascular ultrasound (IVUS) guided percutaneous coronary intervention (PCI) has potential benefits. This meta-analysis aimed to explore whether IVUS-guided PCI had better short- and long-term prognoses than angiography-guided PCI. METHODS: We retrieved studies from PubMed, Embase, and Cochrane Library. Clinical trials including retrospective and randomized controlled trials (RCTs) that compared IVUS-guided PCI with angiography-guided PCI were included. The patients were followed up after operation at 30 days, 1 year, 2 years, and 3 years. The clinical outcomes were target lesion revascularization (TLR), target vessel revascularization (TVR), and MACEs, including stent thrombosis (ST), myocardial infarction (MI), cardiac death, and all-cause death. The study population included patients with MI, coronary bifurcation lesions, short or long lesions, and unprotected left main coronary artery stenosis (ULMCA). The quality of retrospective trials was evaluated using the Newcastle-Ottawa Scale, and the quality of randomized controlled trials was evaluated using the Jadad score. A total of 20 clinical trials met the criteria. Three trials were randomized controlled trials, while 17 were retrospective trials. RESULTS: A total of 24,783 patients were included. In observational trials, the OR of MACEs was 0.49 (95% CI: 0.38-0.62) in 30 days, 0.65 (95% CI: 0.58-0.73) in one year, 0.51 (95% CI: 0.36-0.71) in two years, and 0.45 (95% CI: 0.31-0.65) in three years. In patients with long coronary lesions, the OR of MACEs in 1 year was 0.64 (95% CI: 0.28-1.50). In patients with left main artery disease, the OR of MACEs in 3 years was 0.42 (95% CI: 0.26-0.67). Compared with angiography-guided PCI, IVUS-guided PCI was associated with a lower incidence of MACEs during the same following period. CONCLUSION: Compared with angiography-guided PCI, IVUS-guided PCI has better performance in reducing the occurrence of MACEs.

Late Stent Thrombosis After Drug-Coated Balloon Coronary Angioplasty for In-Stent Restenosis.

A 41-year-old woman with chest pain for 6 hours was admitted to our chest pain center, presenting with acute myocardial infarction. Coronary angiography showed acute total occlusion in the proximal left anterior descending artery due to late stent thrombosis. After thrombus aspiration and intracoronary administration of 0.5 mg tirofiban, repeated angiography showed that no obvious residual stenosis remained. The patient underwent drug-coated balloon angioplasty 69 days ago and was then administered dual antiplatelet treatment (aspirin and clopidogrel) uninterruptedly. Genetic testing found that both cytochrome P450 2C19 (CYP2C19) (G681A) and glycoprotein Ia (GPIa) (C807T, G873A) were hybrid mutant types, demonstrating that the patient was possibly resistant to clopidogrel and aspirin simultaneously. Thus, clopidogrel was replaced by ticagrelor and no more cardiovascular adverse events occurred during the 2-year follow-up.

A small-molecule activator of mitochondrial aldehyde dehydrogenase 2 reduces the severity of cerulein-induced acute pancreatitis.

Acute pancreatitis (AP) is one of the leading causes of hospital admission for gastrointestinal disorders. Although lipid peroxides are produced in AP, it is unknown if targeting lipid peroxides prevents AP. This study aimed to investigate the role of mitochondrial aldehyde dehydrogenase 2 (ALDH2), a critical enzyme for lipid peroxide degradation, in AP and the possible underlying mechanisms. Cerulein was used to induce AP in C57BL/6 J male mice and pancreatic acinar cells were used to elucidate underlying mechanisms in vitro. Pancreatic enzymes in the serum, lipid peroxidation products malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), and Bcl-2, Bax and cleaved caspase-3 were measured. ALDH2 activation with a small-molecule activator, Alda-1, reduced the levels of the pancreatic enzymes in the serum and the lipid peroxidation products MDA and 4-HNE. In addition, Alda-1 decreased Bax and cleaved caspase-3 expression and increased Bcl-2 expression in vivo and in vitro. In conclusion, ALDH2 activation by Alda-1 has a protective effect in cerulein-induced AP by mitigating apoptosis in pancreatic acinar cells by alleviating lipid peroxidation.

Aldehyde dehydrogenase 2 protects against sympathetic excitation-induced cardiac fibrosis.

Sympathetic stimulated-cardiac fibrosis imposes great significance on both disease progression and survival in the pathogenesis of many cardiovascular diseases. However, there are few effective therapies targeting it clinically. The cardioprotective effect of aldehyde dehydrogenase 2 (ALDH2) has been explored in many pathological conditions, whether it can exert benefit effects on chronic sympathetic stimulus-induced cardiac fibrosis remains unclear. In this study, we determined to explore the role of ALDH2 on isoproterenol (ISO)-induced cardiac fibroblasts (CF) proliferation and cardiac fibrosis. It was found that ALDH2 enzymatic activity was impaired in ISO-induced HCF proliferation and Aldh2 deficiency promoted mouse CF proliferation. Alda-1, an ALDH2 activator, exerted obvious suppressive effect on ISO-induced HCF proliferation, together with the induction of cell cycle arrest at G0/G1 phase and decreased expression of cyclin E1 and cyclin-dependent kinase 2 (CDK2). Mechanistically, the inhibitory role of Alda-1 on HCF proliferation was achieved by decreasing mitochondrial reactive oxygen species (ROS) production, which was partially reversed by rotenone, an inducer of ROS. In addition, wild-type mice treated with Alda-1 manifested with reduced fibrosis and better cardiac function after ISO pump. In summary, Alda-1 alleviates sympathetic excitation-induced cardiac fibrosis via decreasing mitochondrial ROS accumulation, highlighting ALDH2 activity as a promising drug target of cardiac fibrosis.

ALDH2 (Aldehyde Dehydrogenase 2) Protects Against Hypoxia-Induced Pulmonary Hypertension.

OBJECTIVE: Hypoxia-induced pulmonary hypertension (HPH) increases lipid peroxidation with generation of toxic aldehydes that are metabolized by detoxifying enzymes, including ALDH2 (aldehyde dehydrogenase 2). However, the role of lipid peroxidation and ALDH2 in HPH pathogenesis remain undefined. Approach and Results: To determine the role of lipid peroxidation and ALDH2 in HPH, C57BL/6 mice, ALDH2 transgenic mice, and ALDH2 knockout (ALDH2-/-) mice were exposed to chronic hypoxia, and recombinant tissue-specific ALDH2 overexpression adeno-associated viruses were introduced into pulmonary arteries via tail vein injection for ALDH2 overexpression. Human pulmonary artery smooth muscle cells were used to elucidate underlying mechanisms in vitro. Chronic hypoxia promoted lipid peroxidation due to the excessive production of reactive oxygen species and increased expression of lipoxygenases in lung tissues. 4-hydroxynonenal but not malondialdehyde level was increased in hypoxic lung tissues which might reflect differences in detoxifying enzymes. ALDH2 overexpression attenuated the development of HPH, whereas ALDH2 knockout aggravated it. Specific overexpression of ALDH2 using AAV1 (adeno-associated virus)-ICAM (intercellular adhesion molecule) 2p-ALDH2 and AAV2-SM22αp (smooth muscle 22 alpha)-ALDH2 viral vectors in pulmonary artery smooth muscle cells, but not endothelial cells, prevented the development of HPH. Hypoxia or 4-hydroxynonenal increased stabilization of HIF (hypoxia-inducible factor)-1α, phosphorylation of Drp1 (dynamin-related protein 1) at serine 616, mitochondrial fission, and pulmonary artery smooth muscle cells proliferation, whereas ALDH2 activation suppressed the latter 3. CONCLUSIONS: Increased 4-hydroxynonenal level plays a critical role in the development of HPH. ALDH2 attenuates the development of HPH by regulating mitochondrial fission and smooth muscle cell proliferation suggesting ALDH2 as a potential new therapeutic target for pulmonary hypertension.

Poly (ADP-ribose) polymerase inhibition protects against myocardial ischaemia/reperfusion injury via suppressing mitophagy.

Myocardial ischaemia/reperfusion (I/R) injury attenuates the beneficial effects of reperfusion therapy. Poly(ADP-ribose) polymerase (PARP) is overactivated during myocardial I/R injury. Mitophagy plays a critical role in the development of myocardial I/R injury. However, the effect of PARP activation on mitophagy in cardiomyocytes is unknown. In this study, we found that I/R induced PARP activation and mitophagy in mouse hearts. Poly(ADP-ribose) polymerase inhibition reduced the infarct size and suppressed mitophagy after myocardial I/R injury. In vitro, hypoxia/reoxygenation (H/R) activated PARP, promoted mitophagy and induced cell apoptosis in cardiomyocytes. Poly(ADP-ribose) polymerase inhibition suppressed H/R-induced mitophagy and cell apoptosis. Parkin knockdown with lentivirus vectors inhibited mitophagy and prevented cell apoptosis in H/R-treated cells. Poly(ADP-ribose) polymerase inhibition prevented the loss of the mitochondrial membrane potential (ΔΨm). Cyclosporin A maintained ΔΨm and suppressed mitophagy but FCCP reduced the effect of PARP inhibition on ΔΨm and promoted mitophagy, indicating the critical role of ΔΨm in H/R-induced mitophagy. Furthermore, reactive oxygen species (ROS) and poly(ADP-ribosylation) of CypD and TSPO might contribute to the regulation of ΔΨm by PARP. Our findings thus suggest that PARP inhibition protects against I/R-induced cell apoptosis by suppressing excessive mitophagy via the ΔΨm/Parkin pathway.

ALDH2 deficiency inhibits Ox-LDL induced foam cell formation via suppressing CD36 expression.

Foam cell formation plays an important role in the initiation and progression of atherosclerosis. Aldehyde dehydrogenase 2 (ALDH2), a key enzyme for aldehyde metabolism, is associated with coronary artery disease and affects atherosclerotic plaque vulnerability. However, the role of ALDH2 in foam cell formation remains unclear. Using peritoneal macrophages from ALDH2-deficient and control mice, we found that ALDH2 deficiency suppressed foam cell formation induced by oxidized low-density lipoproteins (ox-LDL) but not acetylated low-density lipoproteins (ac-LDL) ex vivo. After incubation with ox-LDL, ALDH2-deficient macrophages expressed lower levels of CD36 but the expression of other lipid metabolism-related proteins including SRA, LOX-1, ABCA-1, ABCG-1 and ACAT-1 was not changed in ALDH2-/- macrophages. Using CD36 inhibitor, we confirmed that CD36 contributes to the effect of ALDH2 on foam cell formation. PPARγ was downregulated in ox-LDL treated ALDH2-/- macrophages. 4-HNE was increased by ALDH2 deficiency and high concentration of 4-HNE suppressed the expression of PPARγ. These data suggest that ALDH2 plays an important role in foam cell formation via 4-HNE/PPARγ/CD36 pathway.

ALDH2 Activation Inhibited Cardiac Fibroblast-to-Myofibroblast Transformation Via the TGF-ß1/Smad Signaling Pathway.

Pathological stimulus-triggered differentiation of cardiac fibroblasts plays a major role in the development of myocardial fibrosis. Aldehyde dehydrogenase 2 (ALDH2) was reported to exert a protective role in cardiovascular disease, and whether ALDH2 is involved in cardiac fibroblast differentiation remains unclear. In this study, we used transforming growth factor-ß1 (TGF-ß1) to induce the differentiation of human cardiac fibroblasts (HCFs) and adopted ALDH2 activator Alda-1 to verify the influence of ALDH2 on HCF differentiation. Results showed that ALDH2 activity was obviously impaired when treating HCFs with TGF-ß1. Activation of ALDH2 with Alda-1 inhibited the transformation of HCFs into myofibroblasts, demonstrated by the decreased smooth muscle actin (α-actin) and periostin expression, reduced HCF-derived myofibroblast proliferation, collagen production, and contractility. Moreover, application of Smad2/3 inhibitor alleviated TGF-ß1-induced HCF differentiation and improved ALDH2 activity, which was reversed by the application of ALDH2 inhibitor daidzin. Finally, Alda-1-induced HCF alterations alleviated neonatal rat cardiomyocyte hypertrophy, supported by the immunostaining of α-actin. To summarize, activation of ALDH2 enzymatic activity inhibited the differentiation of cardiac fibroblasts via the TGF-ß1/Smad signaling pathway, which might be a promising strategy to relieve myocardial fibrosis of various causes.

Aldehyde dehydrogenase 2 Glu504Lys variant predicts a worse prognosis of acute coronary syndrome patients.

Aldehyde dehydrogenase 2 (ALDH2) Glu504Lys variant was an independent risk factor for acute coronary syndrome (ACS). However, there are lacking researches about the relationship between the variant and prognosis of ACS. In the prospective study, 377 ACS patients were grouped into the wild-type (*1/*1) and the mutation (*2/*2 + *1/*2) groups according to genotype detection. Compared with the wild-type group, incidences of major adverse cardiac events (MACE) and cardiac death were both higher in the mutation group (9.2% vs 21.0%, P = .002; 5.2% vs 12.2%, P = .026); the MACE-free and the cardiac-death-free cumulative survival rates were obviously lower in the mutation group. Moreover, the mutant genotypes were associated with significantly increased risk of MACE and cardiac death (HR 2.443, 95%CI: 1.390-4.296, P = .002; HR 2.727, 95%CI: 1.303-5.708, P = .008). These results suggested that ALDH2 Glu504Lys variant could predict a worse prognosis of ACS patients.

Aldehyde Dehydrogenase-2 Attenuates Myocardial Remodeling and Contractile Dysfunction Induced by a High-Fat Diet.

BACKGROUND/AIMS: Consumption of a high-fat (HF) diet exacerbates metabolic cardiomyopathy through lipotoxic mechanisms. In this study, we explored the role of aldehyde dehydrogenase-2 (ALDH2) in myocardial damage induced by a HF diet. METHODS: Wild-type C57 BL/6J mice were fed a HF diet or control diet for 16 weeks. ALDH2 overexpression was achieved by injecting a lentiviral ALDH2 expression vector into the left ventricle. RESULTS: Consumption of a HF diet induced metabolic syndrome and myocardial remodeling, and these deleterious effects were attenuated by ALDH2 overexpression. In addition, ALDH2 overexpression attenuated the cellular apoptosis and insulin resistance associated with a HF diet. Mechanistically, ALDH2 overexpression inhibited the expression of c-Jun N-terminal kinase (JNK)-1, activated protein 1 (AP-1), insulin receptor substrate 1 (IRS-1), 4- hydroxynonenal, caspase 3, transforming growth factor ß1, and collagen I and III, and enhanced Akt phosphorylation. CONCLUSION: ALDH2 may effectively attenuate myocardial remodeling and contractile defects induced by a HF diet through the regulation of the JNK/AP-1 and IRS-1/Akt signaling pathways. Our study demonstrates that ALDH2 plays an essential role in protecting cardiac function from lipotoxic cardiomyopathy.

Poly(ADP-ribose) polymerase 1 deficiency increases nitric oxide production and attenuates aortic atherogenesis through downregulation of arginase II.

Poly (ADP-ribose) polymerase (PARP) plays an important role in endothelial dysfunction, leading to atherogenesis and vascular-related diseases. However, whether PARP regulates nitric oxide (NO), a key regulator of endothelial function, is unclear so far. We investigated whether inhibition of PARP-1, the most abundant PARP isoform, prevents atherogenesis by regulating NO production and tried to elucidate the possible mechanisms involved in this phenomenon. In apolipoprotein E-deficient (apoE-/- ) mice fed a high-cholesterol diet for 12 weeks, PARP-1 inhibition via treatment with 3,4-dihydro-54-(1-piperindinyl) butoxy-1(2H)-isoquinoline (DPQ) or PARP-1 gene knockout reduced aortic atherosclerotic plaque areas (49% and 46%, respectively). Both the groups showed restored NO production in mouse aortas with reduced arginase II (Arg II) expression compared to that in the controls. In mouse peritoneal macrophages and aortic endothelial cells (MAECs), PARP-1 knockout resulted in lowered Arg II expression. Moreover, phosphorylation of endothelial NO synthase (eNOS) was preserved in the aortas and MAECs when PARP-1 was inhibited. Reduced NO production in vitro due to PARP-1 deficiency could be restored by treating the MAECs with oxidized low-density lipoprotein treatment, but this effect could not be achieved with peritoneal macrophages, which was likely due to a reduction in the expression of induced NOS expression. Our findings indicate that PARP-1 inhibition may attenuate atherogenesis by restoring NO production in endothelial cells and thus by reducing Arg II expression and consequently arginase the activity.