Quercetin Ameliorates Myocardial Injury in Diabetic Rats by Regulating Autophagy and Apoptosis through AMPK/mTOR Signaling Pathway.

A high-glucose environment is involved in the progression of diabetes mellitus (DM). This study aims to explore the regulatory effects of quercetin (QUE) on autophagy and apoptosis after myocardial injury in rats with DM. The type 2 DM rat models were constructed using low-dose streptozotocin (STZ) treatment combined with a high-carbohydrate (HC) diet in vivo. Compared with the control group, the body weight was decreased, whereas blood pressure, blood glucose, and the LVW/BW ratio were increased in the diabetic group. The results showed that the myocardial fibers were disordered in the diabetic group. Moreover, we found that the myocardial collagen fibers, PAS-positive cells, and apoptosis were increased, whereas the mitochondrial structure was destroyed and autophagic vacuoles were significantly reduced in the diabetic group compared with the control group. The expression levels of autophagy-related proteins LC3 and Beclin1 were decreased, whereas the expression levels of P62, Caspae-3, and Bax/Bcl-2 were increased in the diabetic group in vitro and in vivo. Moreover, QUE treatment alleviated the cellular oxidative stress reaction under high-glucose environments. The results of immunoprecipitation (IP) showed that the autophagy protein Beclin1 was bound to Bcl-2, and the binding capacity increased in the HG group, whereas it decreased after QUE treatment, suggesting that QUE inhibited the binding capacity between Beclin1 and Bcl-2, thus leading to the preservation of Beclin1-induced autophagy. In addition, the blood pressure, blood glucose, and cardiac function of rats were improved following QUE treatment. In conclusion, QUE suppressed diabetic myocardial injury and ameliorated cardiac function by regulating myocardial autophagy and inhibition of apoptosis in diabetes through the AMPK/mTOR signaling pathway.

Knockdown of LncRNA Lcn2-204 alleviates sepsis-induced myocardial injury by regulation of iron overload and ferroptosis.

Ferroptosis is an iron-dependent programmed cell death form resulting from lipid peroxidation damage, it plays a key role in organ damage and tumor development from various causes. Sepsis leads to severe host response after infection with high mortality. The long non-coding RNAs (LncRNAs) are involved in different pathophysiological mechanisms of multiple diseases. Here, we used cecal ligation and puncture (CLP) operation to mimic sepsis induced myocardial injury (SIMI) in mouse model, and LncRNAs and mRNAs were profiled by Arraystar mouse LncRNA Array V3.0. Based on the microarray results, 552 LncRNAs and 520 mRNAs were differentially expressed in the sham and CLP groups, among them, LncRNA Lcn2-204 was the highest differentially expressed up-regulated LncRNA. Iron metabolism disorder was involved in SIMI by bioinformatics analysis, meanwhile, myocardial iron content and lipocalin-2 (Lcn2) protein expressions were increased. The CNC network comprised 137 positive interactions and 138 negative interactions. Bioinformatics analysis showed several iron-related terms were enriched and six genes (Scara5, Tfrc, Lcn2, Cp, Clic5, Ank1) were closely associated with iron metabolism. Then, we constructed knockdown LncRNA Lcn2-204 targeting myocardium and found that it ameliorated cardiac injury in mouse sepsis model through modulating iron overload and ferroptosis. In addition, we found that LncRNA Lcn2-204 was involved in the regulation of Lcn2 expression in septic myocardial injury. Based on these findings, we conclude that iron overload and ferroptosis are the key mechanisms leading to myocardial injury in sepsis, knockdown of LncRNA Lcn2-204 plays the cardioprotective effect through inhibition of iron overload, ferroptosis and Lcn2 expression. It may provide a novel therapeutic approach to ameliorate sepsis-induced myocardial injury.

CircMETTL14(11)S upregulated METTL14 and induced CXCR4 to aggravate endothelial inflammation and atherosclerosis.

Endothelial inflammatory response can induce a variety of cardiovascular diseases, including atherosclerosis (AS). As a member of the m6A methyltransferase family, methyltransferase like 14 (METTL14) was reported to propel endothelial inflammation and aggravate AS. In this study, qRT-PCR and western blot analyses were performed to detect the RNA and protein levels of genes. To analyze the cyclic structure and localization of circMETTL14(11)S, agarose gel electrophoresis, subcellular fractionation and FISH assays were conducted. The role of circMETTL14(11)S on endothelial inflammation was exposed by monocyte adhesion assay. Luciferase reporter, chromatin immunoprecipitation (ChIP), pull-down and RNA binding protein immunoprecipitation (RIP) assays were conducted to explore the mechanism of circMETTL14(11)S on endothelial inflammation and AS. We found that circMETTL14(11)S (hsa_circ_0125169) expressed highly in TNF-α-induced endothelial inflammation and positively regulated the expression of METTL14 in human umbilical vein endothelial cells (HUVECs). CircMETTL14(11)S facilitated endothelial inflammation of HUVECs by METTL14. Based on the nuclear location, circMETTL14(11)S was found to activate METTL14 transcription via cooperating with SRY-box transcription factor 2 (SOX2). METTL14 accelerated the m6A methylation and stabilization of C-X-C motif chemokine receptor 4 (CXCR4) mRNA. Further, the facilitation of circMETTL14(11)S/METTL14/CXCR4 on TNF-α-induced endothelial inflammation of HUVECs was verified. Collectively, circMETTL14(11)S/METTL14/CXCR4 axis aggravated endothelial inflammation and AS.

Resveratrol inhibits ferroptosis and decelerates heart failure progression via Sirt1/p53 pathway activation.

Resveratrol is an organic compound widely studied for its therapeutic uses. We investigated whether resveratrol exerts cardioprotective effects by inhibiting ferroptosis via the Sirt1/p53 pathway. A heart failure model was established by aortic coarctation in Sirt1 knockout mice. The superoxide dismutase (SOD), glutathione (GSH) levels and mitochondrial morphology in murine heart tissues were assessed at different time points to determine the role of ferroptosis in heart failure progression. The cardiac function of mice with heart failure was evaluated by determining the brain natriuretic peptide (BNP) and sST2 concentration and conducting echocardiography. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were transfected with the p53 K382R mutant and Sirt1 interference lentiviral vectors. Immunoprecipitation (IP) experiments were performed to investigate whether Sirt1 influences ferroptosis via p53 K382 acetylation and SLC7A11 expression modulation. Resveratrol improved cardiac function in mice and decelerated ferroptosis and fibrosis progression in heart failure. However, the ability of resveratrol to prevent ferroptosis and treat heart failure was lost after silencing Sirt1. Sirt1 reduced ferroptosis by diminishing the levels of p53 K382 acetylation, reducing the degradation of SLC7A11, and increasing the levels of GSH and glutathione peroxidase 4 (GPX4) in cells. In conclusion, by activating the Sirt1/p53 pathway in heart failure, resveratrol decreased the depletion of SLC7A11, inhibited ferroptosis, and improved cardiac function.

ALDH2 attenuates ischemia and reperfusion injury through regulation of mitochondrial fusion and fission by PI3K/AKT/mTOR pathway in diabetic cardiomyopathy.

The function of mitochondrial fusion and fission is one of the important factors causing ischemia-reperfusion (I/R) injury in diabetic myocardium. Aldehyde dehydrogenase 2 (ALDH2) is abundantly expressed in heart, which involved in the regulation of cellular energy metabolism and stress response. However, the mechanism of ALDH2 regulating mitochondrial fusion and fission in diabetic myocardial I/R injury has not been elucidated. In the present study, we found that the expression of ALDH2 was downregulated in rat diabetic myocardial I/R model. Functionally, the activation of ALDH2 resulted in the improvement of cardiac hemodynamic parameters and myocardial injury, which were abolished by the treatment of Daidzin, a specific inhibitor of ALDH2. In H9C2 cardiomyocyte hypoxia-reoxygenation model, ALDH2 regulated the dynamic balance of mitochondrial fusion and fission and maintained mitochondrial morphology stability. Meanwhile, ALDH2 reduced mitochondrial ROS levels, and apoptotic protein expression in cardiomyocytes, which was associated with the upregulation of phosphorylation (p-PI3KTyr458, p-AKTSer473, p-mTOR). Moreover, ALDH2 suppressed the mitoPTP opening through reducing 4-HNE. Therefore, our results demonstrated that ALDH2 alleviated the ischemia and reperfusion injury in diabetic cardiomyopathy through inhibition of mitoPTP opening and activation of PI3K/AKT/mTOR pathway.

Mechanisms of Quercetin against atrial fibrillation explored by network pharmacology combined with molecular docking and experimental validation.

Atrial fibrillation (AF) is a common atrial arrhythmia for which there is no specific therapeutic drug. Quercetin (Que) has been used to treat cardiovascular diseases such as arrhythmias. In this study, we explored the mechanism of action of Que in AF using network pharmacology and molecular docking. The chemical structure of Que was obtained from Pubchem. TCMSP, Swiss Target Prediction, Drugbank, STITCH, Pharmmapper, CTD, GeneCards, DISGENET and TTD were used to obtain drug component targets and AF-related genes, and extract AF and normal tissue by GEO database differentially expressed genes by GEO database. The top targets were IL6, VEGFA, JUN, MMP9 and EGFR, and Que for AF treatment might involve the role of AGE-RAGE signaling pathway in diabetic complications, MAPK signaling pathway and IL-17 signaling pathway. Molecular docking showed that Que binds strongly to key targets and is differentially expressed in AF. In vivo results showed that Que significantly reduced the duration of AF fibrillation and improved atrial remodeling, reduced p-MAPK protein expression, and inhibited the progression of AF. Combining network pharmacology and molecular docking approaches with in vivo studies advance our understanding of the intensive mechanisms of Quercetin, and provide the targeted basis for clinical Atrial fibrillation treatment.

Changes of Necroptosis in Irbesartan Medicated Cardioprotection in Diabetic Rats.

BACKGROUND: Diabetic cardiomyopathy (DCM) is strongly linked to microvascular disease, renin-angiotensin system (RAS) activation, cardiac inflammation and cell apoptosis. Irbesartan is an angiotensin II (Ang II) receptor antagonist in RAS system, which inhibited the conversion of Ang I into Ang II, while the specific mechanism is still obscure. OBJECTIVE: This study aims to investigate the expressions necroptosis RIP1-RIP3-MLKL pathway in myocardium of diabetic rats, and the protective action of irbesartan on myocardial damage. MATERIALS AND METHODS: In our study, 30 Sprague-Dawley rats were divided into 5 groups: CON4W, high glucose and high caloric (HC4W), diabetes mellitus 4 weeks (DM4W group), diabetes mellitus 8 weeks (DM8W group), and irbesartan diabetes 8 weeks (Ir DM8W group). RESULTS: We discovered that as diabetes progresses, the rats gradually lost weight, the HW/BW ratio were increased gradually, and the cardiac function became worse accompanied with the aggravation of inflammatory injury. Meanwhile, the myocardial fibers and cells were disordered, and the expression of positive substances, RIP1 and RIP3 increased significantly. The mRNA and protein levels of myocardial RIP1, RIP3 and MLKL were all increased with the progression of DM. After the intervention of irbesartan in diabetic rats, the cardiac function was improved, whereas inflammatory injury and HW/BW ratio were decreased. Also, the myocardial fibrosis injury was attenuated, and the PAS positive substances, RIP1 and RIP3 were significantly decreased. The curative effect of irbesartan was related to decreased myocardial RIP1, RIP3 and MLKL mRNA and protein levels. CONCLUSION: In conclusion, irbesartan has a cardioprotective effect on the diabetic rats, and its mechanism may be connected with inhibition of RIP1-RIP3-MLKL pathway.

Corrigendum to "ALDH2 Overexpression Alleviates High Glucose-Induced Cardiotoxicity by Inhibiting NLRP3 Inflammasome Activation".

[This corrects the article DOI: 10.1155/2019/4857921.].

Simvastatin protects heart function and myocardial energy metabolism in pulmonary arterial hypertension induced right heart failure.

The favorable effect of simvastatin on pulmonary arterial hypertension (PAH) has been well defined despite the unknown etiology of PAH. However, whether simvastatin exerts similar effects on PAH induced right heart failure (RHF) remains to be determined. We aimed to investigate the function of simvastatin in PAH induced RHF. Rats in the RHF and simvastatin groups were injected intraperitoneally with monocrotaline to establish PAH-induced RHF model. The expression of miR-21-5p in rat myocardium was detected and miR-21-5p expression was inhibited using antagomiRNA. The effect of simvastatin on hemodynamic indexes, ventricular remodeling of myocardial tissues, myocardial energy metabolism, and calmodulin was explored. Dual-luciferase reporter system was used to verify the binding relationship between miR-21-5p and Smad7. In addition, the regulatory role of simvastatin in Smad7, TGFBR1 and Smad2/3 was investigated. Simvastatin treatment improved hemodynamic condition, myocardial tissue remodeling, and myocardial energy metabolism, as well as increasing calmodulin expression in rats with PAH-induced RHF. After simvastatin treatment, the expression of miR-21-5p in myocardium of rats was decreased significantly. miR-21-5p targeted Smad7 and inhibited the expression of Smad7. Compared with RHF rats, the expressions of TGFBR1 and Smad2/3 in myocardium of simvastatin-treated rats were decreased significantly. Collectively, we provided evidence that simvastatin can protect ATPase activity and maintain myocardial ATP energy reserve through the miR-21-5p/Smad/TGF-ß axis, thus ameliorating PAH induced RHF.

MiR-324-3p Regulates Fibroblast Proliferation via Targeting TGF-ß1 in Atrial Fibrillation.

Atrial fibrillation (AF), one of the common clinical arrhythmias, lacks effective treatment manners. Cardiac fibroblasts play an essential role in myocardial fibrosis and cardiac remodeling, which are involved in AF progression. Reportedly, MicroRNAs (miRNAs) regulate the myocardial fibrosis in AF. However, whether miR-324-3p involves myocardial fibrosis in AF and the tentative molecular mechanisms of miR-324-3p regulating cardiac fibroblasts during AF remains unknown. In the present study, miR-324-3p was found to be decreased in patients with AF and AF rat model. Next, we investigated the effect of miR-324-3p on myocardial fibroblast proliferation through miR-324-3p overexpression and found that miR-324-3p inhibited fibroblast proliferation in vitro. Furthermore, we found that miR-324-3p directly targeted transforming growth factor ß1 in fibroblast, which may be involved in the development of myocardial fibrosis during AF. Meanwhile, miR-324-3p mimics treatment suppressed the PI3K/AKT signaling pathway in fibroblast. These results demonstrated a molecular mechanism of miR-324-3p regulating fibroblast proliferation in vitro, which might provide a novel potential treatment manner in AF in clinic.

[Correlation of plasma N-acetyl-neuraminic acid level with TIMI risk stratification and clinical outcomes in patients with acute coronary syndrome].

OBJECTIVE: To explore the correlation of plasma N-acetyl-neuraminic acid level with Thrombolysis In Myocardial Infarction (TIMI) risk score and clinical outcomes of patients with acute coronary syndrome (ACS). METHODS: We consecutively enrolled 708 consecutive patients (401 male and 307 female, mean age 63.6±10.6 years) undergoing coronary angiography in our hospital between October, 2018 and July, 2019, including 597 patients with ACS and 111 without ACS (control group). The patients with ACS group were divided into high (n=104), moderate (n=425) and low (n=68) risk groups according to their TIMI risk scores. All the participants were examined for plasma Neu5Ac level using liquid chromatography-tandem mass spectrometry and underwent coronary angiography with their Gensini scores calculated. The patients with ACS were followed up after discharge for a mean of 15 months for the occurrence of major adverse cardiac events (Mace). Binary logistic regression analysis was performed to identify the risk factors of Mace in these patients. RESULTS: Plasma Neu5Ac levels were significantly higher in ACS group than in the control group (P < 0.05). ROC curve analysis showed that plasma Neu5Ac level could assist in the diagnosis of ACS (0.648 [0.597-0.699]) with a sensitivity of 39.2% and a specificity of 86.5% at the cutoff value of 288.50 ng/mL. In the ACS patients, plasma Neu5Ac level was significantly higher in the high-risk group than in the moderate-risk and low-risk groups (P < 0.05) and could assist in the diagnosis of a high risk (0.645 [0.588-0.703]) with a sensitivity of 42.3% and a specificity of 80.1% at the cutoff value of 327.50 ng/ mL. Plasma Neu5Ac was positively correlated with age, serum uric acid, creatinine, lipoprotein a, Ddimer, C-reactive protein, MB isoform of creatine kinase and Gensini score and negatively correlated with high-density lipoprotein level. During the followup, 80 ACS patients experienced Mace, who had significantly higher plasma Neu5Ac level than those without Mace (n=517). Logistic regression analysis showed that plasma Neu5Ac level and a history of previous stroke were independent risk factors for the occurrence of Mace. CONCLUSIONS: Plasma Neu5Ac level can provide assistance in the diagnosis and risk stratification of ACS and is an independent risk factor for prognosis of ACS patients.

Docosahexaenoic acid inhibits Ca2+ influx and downregulates CaSR by upregulating microRNA-16 in pulmonary artery smooth muscle cells.

Docosahexaenoic acid (DHA) is reported to have the potential to ameliorate pulmonary arterial hypertension (PAH), while the specific mechanism is still obscure. This study aims to investigate the function of DHA in pulmonary artery smooth muscle cells (PASMCs) and explore the underlying mechanism. In our study, DHA was used to incubate PASMCs. Cytosolic-free Ca2+ concentration ([Ca2+ ]cyt) was measured using Fluo-3 AM method. Real-time polymerase chain reaction was used to detect microRNA-16 (miR-16) and calcium-sensing receptor (CaSR) messenger RNA expression levels. CCK-8 assay, BrdU assay, and Transwell assay were employed to detect the effects of DHA on proliferation and migration of PASMCs. CaSR was confirmed as a direct target of miR-16 using dual-luciferase assay, polymerase chain reaction, and Western blot analysis. It was found that DHA significantly inhibited PASMC proliferation and migration and decreased [Ca2+ ]cyt. After transfection of miR-16 mimics, proliferation and migration ability of PASMCs were significantly inhibited, whereas opposite effects were observed after miR-16 inhibition. [Ca2+ ]cyt was also inhibited by miR-16 transfection. DHA then promoted the expression of miR-16, and the effects of DHA on PASMCs were annulled when miR-16 was inhibited. CaSR was identified as a direct target of miR-16. CaSR was inhibited directly by miR-16 and indirectly by DHA. In conclusion, DHA inhibits the proliferation and migration of PASMCs, and probably ameliorates PAH via regulating miR-16/CaSR axis.

[Expression of NLRP1 inflammasomes in myocardial tissue of diabetic rats].

OBJECTIVE: To observe the expression of NLRP1 inflammasomes in myocardial tissues in rats with a high-fat and highsugar diet and in diabetic rats analyze the role of NLRP1 inflammasomes in the pathogenesis of diabetic cardiomyopathy. METHODS: Male SD rats were divided into normal control group, high-sugar and high-fat diet (HC) group and diabetes group. Rat models of diabetes were established by intraperitoneal injection of streptozotocin (STZ; 30 mg/kg). Serum levels of cholesterol (TC), triglyceride (TG), and fasting insulin (FINS) were measured after 8 weeks of feeding, and the insulin resistance index (IRI) and insulin sensitivity index (ISI) were calculated; Echocardiographic evaluation of cardiac structure and function was performed, and Western blotting and real-time fluorescent quantitative PCR (RT-qRCP) were used to detect the protein and mRNA expressions of NLRP1, ASC, and caspase 1 in the myocardial tissue. RESULTS: Compared with the control rats, the rats in the HC group had significantly increased body weight (BW), serum levels of TG and TC, mRNA expressions of NLRP1 and caspase 1, and the protein expression of NLRP1 (P < 0.01) without significant changes in FINS, IRI, ISI, or cardiac ultrasound findings (P > 0.05) or in myocardial ASC and caspase 1 protein expressions or serum levels of IL-1ß and IL-18 (P > 0.05). In the diabetic rats, TC, TG, and FBG levels increased and FINS, ISI decreased significantly (P < 0.01); the left ventricular end-diastolic diameter (LVID) and the left ventricular end-systolic diameter (LVSD) increased while the ejection fraction (LVEF), short axis shortening rate (FS), and E/A ratio all decreased. The expressions of NLRP1/ASC/caspase 1 pathway mRNA and NLRP1 and caspase 1 proteins also increased but myocardium ASC protein expression did not show significant changes in the diabetic rats (P > 0.05). IL-1ß and IL-18 levels were also significantly higher in the diabetic rats than in the control group (P < 0.05). Compared with those in HC group, the diabetic rats showed significantly increased serum FBG and decreased FINS, ISI and BW (P < 0.01) with decreased LVSD, LVEF and E/A ratio and increased levels of NLRP1 and caspase 1 protein expressions and serum L-1ß and IL-18 levels (P < 0.01). CONCLUSIONS: Diabetes can cause abnormal changes in cardiac structure and functions and induce inflammatory response in the myocardium, which may be related to the activation of NLRP1/ASC/ caspase 1 inflammasomes.

Effects of irbesartan on myocardial injury in diabetic rats: The role of NLRP3/ASC/Caspase-1 pathway.

To observe the mechanism of myocardial injury in diabetic rats after irbesartan intervention and analyze the role of nucleotide binding oligomerization domain-like receptor protein 3 (NLRP3) inflammatory pathway. The experiment was divided into four groups: normal control group (CON), high glucose and high caloric diet group (HC), diabetes group (DM) and diabetes+irbesartan group (DM+Ir). Compared with CON group, in HC group, triglyceride, total cholesterol and fasting blood glucose levels were increased; however, there was no significant difference of the cardiac function, the degree of myocardial fibrosis, NLRP3, ASC, Caspase-1 mRNA and protein expressions and the releasing of inflammatory factors interleukin (IL)-1ß and IL-18. Compared with HC group, in DM group, triglyceride, total cholesterol, fasting blood glucose, IL-1ß and IL-18 levels, NLRP3, ASC, Caspase-1 mRNA and protein expressions and the degree of myocardial fibrosis were increased, but the cardiac function was decreased. Compared with DM group, there were no changes in total cholesterol and fasting blood glucose, the degree of myocardial fibrosis cardiac function was attenuated, NLRP3, ASC, Caspase-1 expressions, IL-1ß and IL-18 levels were reduced in DM+Ir group. The results suggested that irbesartan may exert myocardial protection by inhibiting the expression of the NLRP3/ASC/Caspase-1 pathway in diabetic rats.

MicroRNA-143-5p modulates pulmonary artery smooth muscle cells functions in hypoxic pulmonary hypertension through targeting HIF-1α.

This paper explores the potential mechanism of microRNA-143-5p regulation effects on pulmonary artery smooth muscle cells (PASMCs) functions in hypoxic pulmonary hypertension (HPH) via targeting HIF-1a, which may offer a new idea for HPH therapy. PASMCs were transfected with mimics control/miR-143-5p mimics or inhibitor control/miR-143-5p inhibitor. We used Western blotting and RT-qPCR to detect the protein and mRNA expressions, CCK-8 assay to detect cellular viability, Annexin V-FITC/PI staining and caspase- 3/cleaved caspase-3 protein to evaluate cellular apoptosis, transwell migration experiment for cellular migration measurement and Dual luciferase reporter gene assay to prove the target of miR-143-5p. Cells under hypoxic condition presented the decreased protein and mRNA expressions of α-smooth muscle actin (SM-α-actin), Myocardin, smooth muscle myosin heavy chain (SMMHC), and smooth muscle-22α (SM22α), Calponin1 and Hypoxia-inducible factor-1α(HIF-1α), the increased cell viability and miR-143-5p level; Overexpression of miR-143-5p obviously reduced vascular smooth muscle-specific contraction marker protein levels and cellular apoptosis, increased cellular migration of PASMCs with hypoxia stimulation; Low-expression of miR-143-5p caused the opposite changes, while co-transfected with Si HIF-1 α blocked the beneficial effects of miR-143-5p inhibition on PASMCs under hypoxia. MicroRNA-143-5p can promote the phenotype conversion, proliferation and migration of pulmonary artery smooth muscle cells under hypoxic condition through direct targeting of HIF-1α.

Activation of ALDH2 attenuates high glucose induced rat cardiomyocyte fibrosis and necroptosis.

Necroptosis is one of a regulated programmed death mode, fibrosis is closely related with cell death. It has been reported that inhibition of necroptosis can play the protective role in cardiac ischemia and reperfusion injury, stroke and other diseases, but the mechanisms of aldehyde dehydrogenases 2 (ALDH2) against high glucose induced neonatal rat ventricular primary cardiomyocytes fibrosis and necroptosis had not been elucidated clearly. This study was to observe the effect of ALDH2 on high glucose (HG) induced myocardial fibrosis and necroptosis in primary rat cardiomyocytes model. In contrast to normal glucose group, in HG group, with the decreases of ALDH2 activity, mRNA and protein levels, the cardiomyocytes viability was decreased, reactive oxygen species (ROS), the inflammation factors - tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1ß (IL-1ß) levels, collagen I (col I) and col III mRNA expressions and tissue inhibitors of matrix metalloproteinase 4 (TIMP4) protein expression were increased, while matrix metalloproteinase 14 (MMP14) protein level, the ratio of MMP14/TIMP4 were decreased, and the necroptosis key factors - the receptor interacting protein 1 (RIP1), RIP3 and mixed lineage kinase domain-like protein (MLKL) at mRNA and protein expressions were increased, the inflammasome core proteins - NLRP3 and ASC protein expressions were also increased, the apoptosis rate and necrosis rate were also increased. When the cardiomyocytes were treated with Alda-1 (the ALDH2 agonist) in HG intervention, the cell viability, ALDH2 activity, mRNA and protein levels, MMP14 protein level, the ratio of MMP14/TIMP4 were higher, ROS and TNF-α, IL-6, IL-1ß levels, RIP1, RIP3, MLKL, NLRP3 and ASC expressions, col I and col III, TIMP4 expressions, the apoptosis rate and necrosis rate were lower than in HG group. Daidzin, the antagonist of ALDH2 abolished the role of Alda-1. In summary, ALDH2 maybe is a key regulator in high glucose induced cardiomyocytes injury. Activation of ALDH2 prevented the happening of fibrosis, apoptosis and necroptosis in high glucose induced primary cardiomyocytes injury model, the protective effects were related to the inhibiting of oxidative stress and inflammation, changing of MMP14 and TIMP4, then inhibiting the happening of fibrosis, apoptosis and necroptosis. These findings advance our understanding of the intensive mechanisms of ALDH2's cardioprotection, and provide the targeted basis for clinical diabetes treatment.

ALDH2 Overexpression Alleviates High Glucose-Induced Cardiotoxicity by Inhibiting NLRP3 Inflammasome Activation.

Although the underlying mechanisms of diabetes-induced myocardial injury have not been fully illuminated, the inflammation reaction has been reported intently linked with diabetes. The nucleotide binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome, the key component of pyroptosis, is involved in inflammation reaction, which may be one of the important mechanisms in diabetes-induced myocardial injury. The purpose of this study was to investigate the changes of NLRP3 inflammasome and pyroptosis in high glucose-induced H9C2 cardiac cell injury and investigate whether overexpression of mitochondrial aldehyde dehydrogenase 2 (ALDH2) can reduce the occurrence of pyroptosis. The H9C2 cardiac cells were exposed to 35 mM glucose for 24 h to induce cytotoxicity. Mitochondrial ALDH2 overexpression cardiac cell line was constructed. The results showed in high glucose condition that ALDH2 overexpression significantly increased H9C2 cardiac cell viability, increased mitochondrial ALDH2 activity and protein expression, and reduced mitochondrial reactive oxygen species (ROS) production, 4-hydroxynonenal (4-HNE), and lactate dehydrogenase (LDH) levels; meanwhile, the pyroptosis key components-NLRP3 inflammasome-related proteins, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), cysteine-containing aspartate specific protease 1 (Caspase-1), and interleukin-18 (IL-18) protein expressions-were significantly decreased, and IL-18 and interleukin-1ß (IL-1ß) levels were also decreased. In high glucose-induced cardiac cell injury, ALDH2 overexpression may reduce ROS production, thereby inhibiting the activation of NLRP3 inflammation and cell pyroptosis. ALDH2 gene might play the potential role in the treatment of high glucose-induced H9C2 cardiac cell injury.

[Effects of mitochondrial aldehyde dehydrogenase 2 on autophagy-associated proteins in neonatal rat myocardial fibroblasts cultured in high glucose].

OBJECTIVE: To investigate whether autophagy mediates the effects of aldehyde dehydrogenase 2 (ALDH2) on the proliferation of neonatal rat cardiac fibroblasts cultured in high glucose. METHODS: Cardiac fibroblasts were isolated from neonatal (within 3 days) SD rats and subcultured. The fibroblasts of the third passage, after identification with immunofluorescence staining for vimentin, were treated with 5.5 mmol/L glucose (control group), 30 mmol/L glucose (high glucose group), or 30 mmol/L glucose in the presence of Alda-1 (an ALDH2 agonist), daidzin (an ALDH2 2 inhibitor), or both. Western blotting was employed to detect ALDH2, microtubule-associated protein 1 light chain 3B subunit (LC3B) and Beclin-1 in the cells, and a hydroxyproline detection kit was used for determining hydroxyproline content in cell culture medium; CCK- 8 kit was used for assessing the proliferation ability of the cardiac fibroblasts after the treatments. RESULTS: Compared with the control cells, the cells exposed to high glucose exhibited obviously decreased expressions of ALDH2, Beclin-1 and LC3B and increased cell number and hydroxyproline content in the culture medium. Treatment of the high glucose-exposed cells with Alda-1 significantly increased Beclin-1, LC3B, and ALDH2 protein expressions and lowered the cell number and intracellular hydroxyproline content, whereas the application of daidzin resulted in reverse changes in the expressions of ALDH2, Beclin-1 and LC3B, viable cell number and intracellular hydroxyproline content in high glucose-exposed cells. CONCLUSIONS: Mitochondrial ALDH2 inhibits the proliferation of neonatal rat cardiac fibroblasts induced by high glucose, and the effect is possibly mediated by the up-regulation of autophagy-related proteins Beclin-1 and LC3B.

[Activation of aldehyde dehydrogenase 2 attenuates myocardial injury in diabetic rats by regulating two-pore potassium channel TASK-1].

OBJECTIVE: To investigate the effect of activating aldehyde dehydrogenase 2 (ALDH2) on TASK-1 two-pore potassium channel in myocardial injury of diabetic rats.
 Methods: Diabetic rats were induced by intraperitoneal injection of streptozotocin (55 mg/kg). The diabetic rats were divided into 4 groups: normal group, diabetes at 4th week (DM4W) group, diabetes at 8th week (DM8W) group, and diabetes at 8th week+low concentration of ethanol intervention (DM8W+EtOH) group. The cardiac function of rats was determined by cardiac ultrasonography. The content of hydroxyproline was detected by ELISA. The appearance of myocardial morphous and positive material were observed by HE and PAS staining. The protein expression of TASK-1 was detected by Western blot. Whole-cell patch clamp technique was used to record the action potential duration at 30% and 90% repolarization (APD30, APD90) and two-pore potassium channel TASK-1 current in rat ventricular myocytes. Meanwhile, according to the sensitive electrophysiological characteristics of the potassium channel to acid and base, whether it is two-port potassium channel TASK-1current can be determined.
 Results: Compared with the N group, end-diastole left ventricular diameter (LVIDd), end-systolic left ventricular diameter (LVIDs), hydroxyproline content, TASK-1 protein expression increased, APD30 and APD90 extend, left ventricular fractional shortening (LVFS) and left ventricular ejection fraction (LVEF), and TASK-1 current decreased (all P<0.01) in the DM4W group and the DM8W group. HE staining showed that myocardial cell and fiber arrangement disorder, myocyte hypertrophy, myocardial widened and PAS staining reveals that positive material increased in the DM4W group and the DM8W group. Compared with the DM4W group, these changs are more obvious in DM8W rats (P<0.01 or P<0.05). Compared with the DM8W group, in the DM8W+EtOH group, the left ventricular function was restored, the hydroxyproline content and expression of TASK-1 protein were decreased, the TASK-1 current was increased, and APD30 and APD90 were shortened (all P<0.01). HE staining showed that myocardial cell injury was ameliorate and PAS staining showed decreased deposition of positive substances in the DM8W+EtOH group.
 Conclusion: Activation of aldehyde dehydrogenase 2 by low concentration of ethanol can reduce myocardial injury and fibrosis caused by diabetes, and its mechanism may be related to the changes of the two-por potassium channel TASK-1.