Reduced Cardiomyocyte Apoptosis Research Articles

Effect of Hexadecyl Azelaoyl Phosphatidylcholine on Cardiomyocyte Apoptosis in Myocardial Ischemia-Reperfusion Injury: A Hypothesis.

Reperfusion after myocardial ischemia can induce cardiomyocyte death, known as myocardial reperfusion injury. The pathophysiology of the process of reperfusion suggests the confluence multiple pathways. Recent studies have focused on the inflammatory response, which is considered to be the main mechanism during the process of myocardial ischemia-reperfusion injury and can cause cardiomyocyte apoptosis. Peroxisome proliferator-activated receptors gamma activated by endogenous ligands and exogenous ligand can decrease the inflammatory response in cardiomyocytes. Thiazolidinediones are synthetic, high-affinity, selective ligands for peroxisome proliferator-activated receptors gamma, and can inhibit the inflammatory response, decrease myocardial infarct size, and protect cardiac function. However, thiazolidinediones, including rosiglitazone and pioglitazone, can also contribute to adverse cardiovascular events such as congestive heart failure. Therefore, there are some limitations to the use of thiazolidinediones. Most endogenous ligands were of low affinity until hexadecyl azelaoyl phosphatidylcholine was identified as a high-affinity ligand and agonist for peroxisome proliferator-activated receptors gamma. Hexadecyl azelaoyl phosphatidylcholine binds recombinant peroxisome proliferator-activated receptors with an affinity (Kd(app) ≈40 nM) which is equivalent to rosiglitazone. Therefore, hexadecyl azelaoyl phosphatidylcholine is a specific peroxisome proliferator-activated receptors gamma agonist. Given these findings, we hypothesized that the use of hexadecyl azelaoyl phosphatidylcholine can activate the peroxisome proliferator-activated receptors gamma signal pathways and prevent the inflammatory response process of myocardial ischemia-reperfusion injury, with reduced cardiomyocyte apoptosis and death.

Heme Oxygenase-1 in Macrophages Drives Septic Cardiac Dysfunction via Suppressing Lysosomal Degradation of Inducible Nitric Oxide Synthase

To date, our understanding of the role of HO-1 (heme oxygenase-1) in inflammatory diseases has mostly been limited to its catalytic function and the potential for its heme-related catabolic products to suppress inflammation and oxidative stress. Whether and how HO-1 in macrophages plays a role in the development of septic cardiac dysfunction has never been explored. Here, we investigated the role of macrophage-derived HO-1 in septic cardiac dysfunction. Intraperitoneal injection of lipopolysaccharide significantly activated HO-1 expression in cardiac infiltrated macrophages. Surprisingly, we found that myeloid conditional HO-1 deletion in mice evoked resistance to lipopolysaccharide-triggered septic cardiac dysfunction and lethality in vivo, which was accompanied by reduced cardiomyocyte apoptosis in the septic hearts and decreased peroxynitrite production and iNOS (inducible NO synthase) in the cardiac infiltrated macrophages, whereas proinflammatory cytokine production and macrophage infiltration were unaltered. We further demonstrated that HO-1 suppression abolished the lipopolysaccharide-induced iNOS protein rather than mRNA expression in macrophages. Moreover, we confirmed that the inhibition of HO-1 promoted iNOS degradation through a lysosomal rather than proteasomal pathway in macrophages. Suppression of the lysosomal degradation of iNOS by bafilomycin A1 drove septic cardiac dysfunction in myeloid HO-1-deficient mice. Mechanistically, we demonstrated that HO-1 interacted with iNOS at the flavin mononucleotide domain, which further prevented iNOS conjugation with LC3 (light chain 3) and subsequent lysosomal degradation in macrophages. These effects were independent of HO-1's catabolic products: ferrous ion, carbon monoxide, and bilirubin. Our results indicate that HO-1 in macrophages drives septic cardiac dysfunction. The mechanistic insights provide potential therapeutic targets to treat septic cardiac dysfunction.

Protective effect of miR378* on doxorubicin‐induced cardiomyocyte injury via calumenin

Doxorubicin (Dox) is a highly effective antitumor antibiotic, however myocardial toxicity severely limits its use clinically. The pathogenesis of doxorubicin‐induced cardiomyopathy is unclear. In Dox cardiomyopathy mice, there is a decline in cardiac function, a change in myocardial pathology and a reduction in miR378* expression. Expression changes in calumenin, an endoplasmic reticulum stress (ERS) chaperone protein and pathway factor, as well as apoptosis, were observed in cardiomyocytes after doxorubicin‐induced injury. However, miR378* increased calumenin expression, eased ERS, and reduced cardiomyocyte apoptosis, while, silencing miR378* reduced calumenin expression, aggravated ERS, and increased cardiomyocyte apoptosis. The above results indicate that miR378* alleviates ERS and inhibits the activation of the ERS‐mediated apoptosis signaling pathway in cardiomyocytes via regulating calumenin expression, thereby reducing cardiomyocyte apoptosis after doxorubicin‐induced injury. Increasing miR378* expression may be a new way to improve cardiac function and quality of life in patients with Dox cardiomyopathy.

Melatonin prevents Drp1-mediated mitochondrial fission in diabetic hearts through SIRT1-PGC1α pathway.

Myocardial contractile dysfunction is associated with an increase in mitochondrial fission in patients with diabetes. However, whether mitochondrial fission directly promotes diabetes‐induced cardiac dysfunction is still unknown. Melatonin exerts a substantial influence on the regulation of mitochondrial fission/fusion. This study investigated whether melatonin protects against diabetes‐induced cardiac dysfunction via regulation of mitochondrial fission/fusion and explored its underlying mechanisms. Here, we show that melatonin prevented diabetes‐induced cardiac dysfunction by inhibiting dynamin‐related protein 1 (Drp1)‐mediated mitochondrial fission. Melatonin treatment decreased Drp1 expression, inhibited mitochondrial fragmentation, suppressed oxidative stress, reduced cardiomyocyte apoptosis, improved mitochondrial function and cardiac function in streptozotocin (STZ)‐induced diabetic mice, but not in SIRT1−/− diabetic mice. In high glucose‐exposed H9c2 cells, melatonin treatment increased the expression of SIRT1 and PGC‐1α and inhibited Drp1‐mediated mitochondrial fission and mitochondria‐derived superoxide production. In contrast, SIRT1 or PGC‐1α siRNA knockdown blunted the inhibitory effects of melatonin on Drp1 expression and mitochondrial fission. These data indicated that melatonin exerted its cardioprotective effects by reducing Drp1‐mediated mitochondrial fission in a SIRT1/PGC‐1α‐dependent manner. Moreover, chromatin immunoprecipitation analysis revealed that PGC‐1α directly regulated the expression of Drp1 by binding to its promoter. Inhibition of mitochondrial fission with Drp1 inhibitor mdivi‐1 suppressed oxidative stress, alleviated mitochondrial dysfunction and cardiac dysfunction in diabetic mice. These findings show that melatonin attenuates the development of diabetes‐induced cardiac dysfunction by preventing mitochondrial fission through SIRT1‐PGC1α pathway, which negatively regulates the expression of Drp1 directly. Inhibition of mitochondrial fission may be a potential target for delaying cardiac complications in patients with diabetes.

Association of polymorphisms in MALAT1 with risk of coronary atherosclerotic heart disease in a Chinese population

BackgroundMetastasis associated lung adenocarcinoma transcript 1 (MALAT1) plays an important role in vascular remodeling. Down-regulation of MALAT1 can inhibit the proliferation of vascular endothelial cells and vascular smooth muscle cells, reduce cardiomyocyte apoptosis and improve left ventricular function, which is closely linked to numerous pathological processes such as coronary atherosclerotic heart disease (CAD). The aim of this study was to investigate whether polymorphisms in MALAT1 were associated with the susceptibility to CAD.MethodsA total of 508 CAD patients and 562 age-, gender-, and ethnicity-matched controls were enrolled in this study. Four polymorphisms in MALAT1 (i.e., rs11227209, rs619586, rs664589, and rs3200401) were genotyped using a TaqMan allelic discrimination assay.ResultsThe rs619586 AG/GG genotypes and G allele were associated with a reduced risk of CAD (AG/GG vs. AA: adjusted OR = 0.66, 95% CI: 0.48–0.91; G vs. A: adjusted OR = 0.68, 95% CI: 0.51–0.90). Stratification analyses showed that CAD patients with rs11227209 CG/GG, rs619586 AG/GG, and rs3200401 CT/TT genotypes exhibited lower levels of TCH (P = 0.02, 0.04, and 0.02, respectively). Moreover, CGCC haplotype was associated with a decreased risk of CAD (OR = 0.28, 95% CI: 0.16–0.48). Multivariate logistic regression analysis identified some independent risk factors for CAD, including rs619586 and rs664589. Subsequent combined analysis showed that the combined genotypes of rs619586AG/GG and rs664589CC were associated with a reduced risk of CAD (OR = 0.29; 95%CI, 0.16–0.53).ConclusionsThese findings indicate that rs619586AG/GG genotypes in MALAT1 may protect against the occurrence of CAD.

Serum-Derived Extracellular Vesicles Protect Against Acute Myocardial Infarction by Regulating miR-21/PDCD4 Signaling Pathway.

Acute myocardial infarction (AMI) represents a leading cause of morbidity and mortality worldwide. Extracellular vesicles (EVs) are being recognized as a promising therapeutic approach in protecting against MI. Serum is a rich source of EVs, which transports various microRNAs (miRNAs, miRs). EVs from serum have been shown beneficial for protecting against ischemia-reperfusion injury; however, their roles in AMI are unclear. In addition, whether a miRNA might be responsible for the effects of serum EVs on protecting against AMI is undetermined. Here, we demonstrated that serum EVs significantly reduced cardiomyocytes apoptosis in both cellular and mouse models of AMI, and dramatically attenuated the infarct size in mouse hearts after AMI. Inhibition of miR-21 was shown to reduce the protective effects of serum EVs in inhibiting cardiomyocytes apoptosis. miR-21 was decreased in mouse hearts after AMI, while serum EVs increased that. In addition, the programmed cell death 4 (PDCD4) expression was identified as a target gene of miR-21. Therefore, our study showed the protective effects of serum EVs on AMI, and provided a novel strategy for AMI therapy.

Ivabradine Treatment Reduces Cardiomyocyte Apoptosis in a Murine Model of Chronic Viral Myocarditis.

This study was designed to explore the effects of ivabradine on cardiomyocyte apoptosis in a murine model of chronic viral myocarditis (CVMC). Mice were inoculated intraperitoneally with Coxsackievirus B3 at days 1, 14, and 28, respectively. On day 42, the mice were gavaged with ivabradine for 30 days until the 72nd day. The heart of infected mice was dilated and a large number of interstitial fibroblasts infiltrated into the myocardium on day 42. Compared with the untreated CVMC mice, mice treated with ivabradine showed a significant reduction in heart rate and less impairment of left ventricular function on day 72. The positive apoptosis of myocardial cells in the untreated CVMC group was significantly higher than that of the normal group and was significantly reduced after treatment with ivabradine. The expression levels of Bax and Caspase-3 in the untreated CVMC group were significantly higher than those of the normal group and were apparently reduced in the ivabradine-treated group versus the untreated CVMC group. Bcl-2 showed a high expression in the normal group and low expression in the untreated CVMC group, but its expression level in the ivabradine-treated group were higher than that of the untreated CVMC group. These results indicate that ivabradine could attenuate the expression of Caspase-3 by downregulation of Bax and upregulation of Bcl-2 to prevent the deterioration of cardiac function resulting from ventricular myocyte loss by cardiomyocyte apoptosis.

Butorphanol attenuates myocardial ischemia reperfusion injury through inhibiting mitochondria-mediated apoptosis in mice.

To investigate the role of the opioid receptors agonist butorphanol on mice myocardial ischemia reperfusion (I/R) injury. The left anterior descending of coronary artery was ligatured for 30 min and then reperfusion for 6 h was performed to mimic the mouse myocardial I/R injury. All mice were randomly divided into three groups: sham group, I/R group and I/R + butorphanol group. Blood samples were collected for the measurement of cardiac troponin I (CTnI) and creatine kinase MB (CK-MB) levels. The infarct size was stained by triphenyltetrazolium chloride. The mitochondria morphology was observed by electron microscopy. The expressions of cleaved caspase-9 and -3, p38, ERK and JNK were detected by Western blot. The myocardial infarct size, serum CK-MB and CTn I levels, expression of cleaved caspase-9 and -3, phosphorylation of p38 and JNK were all increased in the I/R group compared with the sham group (all p < 0.01). Butorphanol reduced the myocardial infarct size, serum CTn I and CK-MB levels, expression of cleaved caspase-9 and -3, and phosphorylation levels of p38 and JNK (all p < 0.01). The number of mitochondria and the individual mitochondrial cross-sectional areas were decreased in the I/R mice compared with the sham-operated mice (all p < 0.01). Butorphanol reversed these changes in mitochondrial morphology (all p < 0.01). Butorphanol attenuates myocardial I/R injury through reducing cardiomyocyte apoptosis by inhibiting mitochondria-mediated apoptotic pathway, and blockage of p38 and JNK phosphorylation.

Plasma exosomes induced by remote ischaemic preconditioning attenuate myocardial ischaemia/reperfusion injury by transferring miR-24

Remote ischaemic preconditioning (RIPC) is well known to protect the myocardium against ischaemia/reperfusion injury (IRI). Exosomes are small extracellular vesicles that have become the key mediators of intercellular communication. Various studies have confirmed that circulating exosomes mediate RIPC. However, the underlying mechanisms for RIPC-induced exosome-mediated cardioprotection remain elusive. In our study, we found that the expression level of miR-24 was higher in exosomes derived from the plasma of rats subjected to RIPC than in exosomes derived from the plasma of control rats in vivo. The rat plasma exosomes could be taken up by H9c2 cells. In addition, miR-24 was present in RIPC-induced exosomes and played a role in reducing oxidative stress-mediated injury and decreasing apoptosis by downregulating Bim expression in H2O2-treated H9c2 cells in vitro. In vivo, miR-24 in RIPC-induced exosomes reduced cardiomyocyte apoptosis, attenuated the infarct size and improved heart function. Furthermore, the apoptosis-reducing effect of miR-24 was counteracted by miR-24 antagomirs or inhibitors both in vitro and in vivo. Therefore, we provided evidence that RIPC-induced exosomes could reduce apoptosis by transferring miR-24 in a paracrine manner and that miR-24 in the exosomes plays a central role in mediating the protective effects of RIPC.

Effects of procyanidin on cardiomyocyte apoptosis after myocardial ischemia reperfusion in rats

BackgroundThis study is aimed at investigating the effects of procyanidin on cardiomyocyte apoptosis of myocardial ischemia/reperfusion (I/R) injury in rats.MethodsSprague-Dawley rats were randomly assigned into four groups: control group (normal saline), ischemic group (normal saline), procyanidin low-dose group (procyanidin 50 mg/kg/day) and procyanidin high-dose group (procyanidin 100 mg/kg/day) by intragastric administration for 2 weeks. After last administration, myocardial I/R model was induced by ligating left anterior descending artery for 30 min followed by 120 min of perfusion. The activity of serum creatine kinase mb isoenzyme (CK-MB) was detected after experiment. The content of reactive oxygen species (ROS) was determined by ROS fluorescent probe dihydroethidium; the expressions of p53, Caspase-9, Caspase-3, Bcl-2 and Bax were determined by western blotting; myocardial apoptosis was measured by the method of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling.ResultsCompared with control group, the contents of serum CK-MB, ROS, the expressions of p53, Caspase-9, Caspase-3 and Bax increased significantly in ischemic group, the Bcl-2 expression, Bcl-2/Bax ratio decreased and the cardiomyocyte apoptosis index increased (p < 0.05); compared with ischemic group, the content of CK-MB, ROS, the expressions of p53, Caspase-9, Caspase-3 and Bax decreased, the Bcl-2 expression, Bcl-2/Bax ratio increased and the cardiomyocyte apoptosis index decreased in procyanidin group (p < 0.05).ConclusionsProcyanidin can reduce cardiomyocyte apoptosis after I/R. This beneficial effect is partially dependant on decreased ROS, p53, Caspase-9, Caspase-3 and Bax, as well as increased Bcl-2 and Bcl-2/Bax ratio.

Inhibition of MicroRNA-124 Reduces Cardiomyocyte Apoptosis Following Myocardial Infarction via Targeting STAT3

Background/Aims: MicroRNAs play an important role in regulating myocardial infarction (MI)-induced cardiac injury. MicroRNA-124 (miR-124) plays a vital role in regulating cellular proliferation, differentiation and apoptosis. Although the alteration of miR-124 was confirmed in peripheral blood of MI patients, little is known regarding the biological functions of miR-124 in cardiomyocytes. This study was designed to explore the role of miR-124 in MI and its underlying mechanisms. Methods: Real-time PCR was used to quantify the microRNAs levels. TUNEL and Flow cytometry were performed to measure cell apoptosis. Western blot analysis was employed to detect expression of Bcl-2, Bax, Caspase-3 and STAT3 proteins. Results: We revealed that miR-124 was significantly up-regulated in a mice model of MI and in neonatal rat ventricular myocytes (NRVMs) with H₂O₂ treatment. H₂O₂ treatment induced cardiomyocyte injury with reduced cell viability and enhanced apoptotic cell death, whereas silencing expression of miR-124 by AMO-124 (antisense inhibitor oligodeoxyribonucleotides) alleviated these deleterious changes. AMO-124 decreased the expression of Bax and cleaved-caspase-3 and upregulated the expression of Bcl-2 in H₂O₂-treated NRVMs. Besides, AMO-124 improved mitochondrial dysfunction of NRVMs induced by H₂O₂ treatment. Moreover, antagomir-124 markedly decreased the infarct area and apoptotic cardiomyocytes and improved cardiac function in MI mice. Furthermore, we identified STAT3 as a direct target of miR-124, and downregulation of miR-124 ameliorated the diminished levels of STAT3 and p-STAT3 (Tyr705) in response to H₂O₂ or MI. STAT3 inhibitor, stattic, was shown to attenuate the elevation of p-STAT3 in NRVMs with AMO-124 transfection. Inhibiting of STAT3 activity by stattic abrogated protective effects of AMO-124 on H₂O₂-induced cardiomyocytes apoptosis. Conclusion: Taken together, our data demonstrate that downregulation of miR-124 inhibits MI-induced apoptosis through upregulating STAT3, which suggests the therapeutic potential of miR-124 for myocardial infarction.

Effects of transplantation of hypoxia-inducible factor-1α genemodified cardiac stem cells on cardiac function of heart failure rats after myocardial infarction.

Objective:To evaluate the effects of transplantation of hypoxia-inducible factor-1α (HIF-1α) gene-modified cardiac stem cells (CSCs) on the cardiac function of heart failure rats after myocardial infarction (MI).Methods:Twenty-four Sprague–Dawley rats were randomly divided into three groups: HIF-1α-modified CSCs group, single CSCs group, and model group. The model of heart failure after MI was established by thoracotomy-left anterior descending coronary artery ligation, followed by injection of modified CSCs, single CSCs, and PBS, respectively, 2 weeks later. The results were observed 4 weeks later.Results:CSCs were infected with recombinant adenovirus. HIF-1α mRNA level of HIF-1α-enhanced green fluorescent protein (EGFP)+CSCs group significantly surpassed those of EGFP+CSCs and CSCs groups (p<0.001). Left ventricular ejection fractions (LVEFs) of HIF-1α+CSCs+MI and CSCs+MI groups significantly increased compared with the model group (p<0.001). The difference between LVEFs before and after transplantation was positively correlated with the survival rate of CSCs in infarction border zone (r=0.867, p<0.001). The apoptosis rate of HIF-1α+CSCs+MI group was significantly lower than that of CSCs+MI group (p=0.008). The expression of vascular endothelial growth factor protein in HIF-1α+CSCs+MI group significantly increased, compared with that of MI group (p<0.001). The capillary density of HIF-1α+CSCs+MI group significantly exceeded that of CSCs+MI group (p<0.001).Conclusion:Transplantation of either HIF-1α-modified CSCs or single CSCs reduced cardiomyocyte apoptosis in rats with heart failure after MI, promoted vascular regeneration in infarct area, and improved cardiac function. Particularly, HIF-1α-modified CSCs had more significant effects.

Cardiomyocyte proliferation prevents failure in pressure overload but not volume overload.

Induction of the cell cycle is emerging as an intervention to treat heart failure. Here, we tested the hypothesis that enhanced cardiomyocyte renewal in transgenic mice expressing cyclin D2 would be beneficial during hemodynamic overload. We induced pressure overload by transthoracic aortic constriction (TAC) or volume overload by aortocaval shunt in cyclin D2-expressing and WT mice. Although cyclin D2 expression dramatically improved survival following TAC, it did not confer a survival advantage to mice following aortocaval shunt. Cardiac function decreased following TAC in WT mice, but was preserved in cyclin D2-expressing mice. On the other hand, cardiac structure and function were compromised in response to aortocaval shunt in both WT and cyclin D2-expressing mice. The preserved function and improved survival in cyclin D2-expressing mice after TAC was associated with an approximately 50% increase in cardiomyocyte number and exaggerated cardiac hypertrophy, as indicated by increased septum thickness. Aortocaval shunt did not further impact cardiomyocyte number in mice expressing cyclin D2. Following TAC, cyclin D2 expression attenuated cardiomyocyte hypertrophy, reduced cardiomyocyte apoptosis, fibrosis, calcium/calmodulin-dependent protein kinase IIδ phosphorylation, brain natriuretic peptide expression, and sustained capillarization. Thus, we show that cyclin D2-induced cardiomyocyte renewal reduced myocardial remodeling and dysfunction after pressure overload but not after volume overload.

Pterostilbene attenuates myocardial ischemia-reperfusion injury via the phosphatidylinositol 3'-kinase-protein kinase B signaling pathway.

The current study aimed to evaluate the cardioprotective effects of pterostilbene (PTB) on myocardial ischemia-reperfusion (I/R) injury in rats and identify its possible underlying mechanisms of action. A rat I/R model was established by ligating the left anterior descending coronary artery for 30 min and releasing the ligature to induce reperfusion for 120 min. Serum creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) levels were measured using CK-MB and LDH assay kits and myeloperoxidase (MPO) activity in the myocardium was evaluated using an MPO assay kit. Tumor necrosis factor-α, interleukin (IL)-6 and IL-8 levels were assayed using ELISA kits. Cardiomyocyte apoptosis was measured using terminal deoxynucleotidyl transferase dUTP nick end labeling staining. Levels of protein kinase B (Akt) and phosphorylated Akt (p-Akt) were measured using western blotting. The results demonstrated that treatment with PTB significantly reduced cardiomyocyte apoptosis, significantly increased Bcl-2 and p-Akt levels and decreased Bax expression in the hearts of rats subjected to I/R injury. However, the protective effects induced by PTB were attenuated by LY294002, which inhibits Akt activation. The results of the current study suggest that PTB treatment may reduce the I/R injury-induced apoptosis of cardiomyocytes, which is mediated by the phosphoinositide 3-kinase/Akt signaling pathway.

Honokiol protects against doxorubicin cardiotoxicity via improving mitochondrial function in mouse hearts

Honokiol is a key component of a medicinal herb, Magnolia bark. Honokiol possesses potential pharmacological benefits for many disease conditions, especially cancer. Recent studies demonstrate that Honokiol exerts beneficial effects on cardiac hypertrophy and doxorubicin (Dox)-cardiotoxicity via deacetylation of mitochondrial proteins. However, the effects and mechanisms of Honokiol on cardiac mitochondrial respiration remain unclear. In the present study, we investigate the effect of Honokiol on cardiac mitochondrial respiration in mice subjected to Dox treatment. Oxygen consumption in freshly isolated mitochondria from mice treated with Honokiol showed enhanced mitochondrial respiration. The Dox-induced impairment of mitochondrial respiration was less pronounced in honokiol-treated than control mice. Furthermore, Luciferase reporter assay reveals that Honokiol modestly increased PPARγ transcriptional activities in cultured embryonic rat cardiomyocytes (H9c2). Honokiol upregulated the expression of PPARγ in the mouse heart. Honokiol repressed cardiac inflammatory responses and oxidative stress in mice subjected to Dox treatment. As a result, Honokiol alleviated Dox-cardiotoxicity with improved cardiac function and reduced cardiomyocyte apoptosis. We conclude that Honokiol protects the heart from Dox-cardiotoxicity via improving mitochondrial function by not only repressing mitochondrial protein acetylation but also enhancing PPARγ activity in the heart. This study further supports Honokiol as a promising therapy for cancer patients receiving Dox treatment.

Metabolic profiles revealed anti-ischemia-reperfusion injury of Yangxinshi tablet in Rats

Ethnopharmacological relevanceMyocardial ischemia-reperfusion (I/R) injury is a serious injury that is resulted from the recovery of blood supply after myocardial ischemia. Yangxinshi tablet is a compound Chinese herbal preparation and often used to alleviate the myocardial ischemia in clinical, but its protective mechanism of anti-myocardial ischemia reperfusion injury remains unclear. The objective of this study was to evaluate the anti-I/R injury effect of Yangxinshi tablet on a myocardial I/R rat model and to identify serum biomarker metabolites associated with I/R based on ultra-high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF/MS) metabolomic method, and explore the metabolic mechanism of anti-I/R injury of Yangxinshi tablet. Materials and methodsUnsupervised principle component analysis highlighted significant differences in the metabolome of the myocardial I/R, healthy control and drug-treated rats. Partial least squares-discriminant analysis revealed 25 metabolites as the most potential biomarker metabolites discriminating the myocardial I/R rats and control rats. Most of the metabolites were primarily involved in oxidative stress, energy metabolism, fatty acid metabolism, amino acid metabolism. These metabolites were validated by assessing the efficacy after intragastric administration of Yangxinshit ablet to the myocardial I/R rat model. ResultsBased on metabolomic results, the action mechanism of anti-I/R injury of Yangxinshi tablet was concluded as follows: (1) enhance the ability of scavenging free radicals and reactive oxygen species in vivo; (2) provide energy for myocardium via accelerating the intracellular carnitine transportion to accelerate the oxidation of fatty acid and (3) attenuate ceramide to reduce cardiomyocyte apoptosis. ConclusionsYangxinshi tablet has cardio-protection effects on I/R rats via regulation of multiple metabolic pathways involving in oxidative stress, energy metabolism, fatty acid, and amino acid metabolisms. This study will be meaningful for its clinical application and valuable for further exploring the action mechanism of Yangxinshi tablet.

Methylglyoxal-derived advanced glycation end products contribute to negative cardiac remodeling and dysfunction post-myocardial infarction.

Advanced glycation end-products (AGEs) have been associated with poorer outcomes after myocardial infarction (MI), and linked with heart failure. Methylglyoxal (MG) is considered the most important AGE precursor, but its role in MI is unknown. In this study, we investigated the involvement of MG-derived AGEs (MG-AGEs) in MI using transgenic mice that over-express the MG-metabolizing enzyme glyoxalase-1 (GLO1). MI was induced in GLO1 mice and wild-type (WT) littermates. At 6h post-MI, mass spectrometry revealed that MG-H1 (a principal MG-AGE) was increased in the hearts of WT mice, and immunohistochemistry demonstrated that this persisted for 4weeks. GLO1 over-expression reduced MG-AGE levels at 6h and 4weeks, and GLO1 mice exhibited superior cardiac function at 4weeks post-MI compared to WT mice. Immunohistochemistry revealed greater vascular density and reduced cardiomyocyte apoptosis in GLO1 vs. WT mice. The recruitment of c-kit+ cells and their incorporation into the vasculature (c-kit+CD31+ cells) was higher in the infarcted myocardium of GLO1 mice. MG-AGEs appeared to accumulate in type I collagen surrounding arterioles, prompting investigation in vitro. In culture, the interaction of angiogenic bone marrow cells with MG-modified collagen resulted in reduced cell adhesion, increased susceptibility to apoptosis, fewer progenitor cells, and reduced angiogenic potential. This study reveals that MG-AGEs are produced post-MI and identifies a causative role for their accumulation in the cellular changes, adverse remodeling and functional loss of the heart after MI. MG may represent a novel target for preventing damage and improving function of the infarcted heart.

Effects of nicorandil on PI3K/Akt signaling pathway and its anti-apoptotic mechanisms in coronary microembolization in rats.

Coronary microembolization (CME) is a common complication of percutaneous coronary intervention (PCI) for acute coronary syndrome. It leads to myocardial apoptosis and cardiac dysfunction. Nicorandil pretreatment can prevent PCI-related myocardial injury and reduce the incidence of no- or slow-reflow phenomena. This cardioprotective effect is probably attributable to the suppression of CME-induced cardiomyocyte apoptosis, but the specific mechanisms have not been clarified. We aimed to investigate the protective effects of nicorandil pretreatment on CME-induced myocardial injury and clarify the underlying mechanisms. In vivo studies, we used echocardiography, cardiac-enzymes measurement, hematoxylin–basic fuchsin–picric acid staining, TUNEL assay, and western blot, and found that CME significantly increased apoptotic cardiomyocytes in the infarct and peri-infarct areas in rats. The PI3K/Akt signaling pathway was involved in cardiomyocyte apoptosis. Nicorandil pretreatment given 7 days before CME effectively reduced cardiomyocyte apoptosis and myocardial injuries in rats, mainly through the activation of PI3K/Akt signaling. In vitro studies further showed that nicorandil reduced hypoxia-induced cardiomyocyte apoptosis and improved cardiomyocyte-survival rate. The PI3K-specific inhibitor LY294002 reduced these cardioprotective effects, indicating that they were attributable to the activation of the PI3K/Akt signaling pathway. In conclusion, nicorandil has significant cardioprotective effects in CME mainly through the activation of the PI3K/Akt signaling pathway and reduction of CME-induced cardiomyocyte apoptosis. Our findings may provide important support for the pre-PCI use of nicorandil to reduce post-PCI myocardial injuries.

LncRNA260-specific siRNA targeting IL28RA gene inhibit cardiomyocytes hypoxic/reoxygenation injury.

The interleukin 28 receptor alpha (IL28RA) gene was indicated to be associated with apoptosis. However, it was not clear whether long non-coding RNA 260 (lncRNA 260)-specific siRNA targeting IL28RA gene could inhibit hypoxic reoxygenation (H/R) cardiomyocytes injury or not. To explore the mechanisms underlying the protective effects of lncRNA260-specific siRNA-mediated inhibition of IL28RA from H/R injury in cardiomyocytes, the current research was performed. The primary neonatal rat cardiomyocytes were transfected with three different pairs of siRNA specific to lncRNA260 targeting IL28RA gene and then were undergone with the conditions simulating H/R injury. All three groups of cardiomyocytes treated with lncRNA260-specific siRNA experienced significantly decreased levels of lactate dehydrogenase activity and apoptosis rate relative to the non-treatment and negative control groups (P<0.05), also expressed reduced levels of IL28RA, and increased levels of PI3KCG and Bcl-2/Bax (P<0.05). The lncRNA260-specific siRNA may reduce cardiomyocyte apoptosis associated with H/R injury by decreasing levels of the IL28RA gene product and thus activating the PI3K/AKT signaling pathway.

LncRNA MIAT functions as a competing endogenous RNA to upregulate DAPK2 by sponging miR-22-3p in diabetic cardiomyopathy

We previously established a rat model of diabetic cardiomyopathy (DCM) and found that the expression of long non-coding RNA myocardial infarction–associated transcript (MIAT) was significantly upregulated. The present study was aimed to determine the pathologic role of MIAT in the development of DCM. MIAT knockdown was found to reduce cardiomyocyte apoptosis and improve left ventricular function in diabetic rats. High glucose could increase MIAT expression and induce apoptosis in cultured neonatal cardiomyocytes. The results of luciferase reporter assay and RNA immunoprecipitation assay revealed that MIAT was targeted by miR-22-3p in an AGO2-dependent manner. In addition, the 3′-untranslated region of DAPK2 was fused to the luciferase coding region and transfected into HEK293 cells with miR-22-3p mimic, and the results showed that DAPK2 was a direct target of miR-22-3p. Our findings also indicated that MIAT overexpression could counteract the inhibitory effect of miR-22-3p on DAPK2. Moreover, MIAT knockdown was found to reduce DAPK2 expression and inhibit apoptosis in cardiomyocytes exposed to high glucose. In conclusion, our study demonstrates that MIAT may function as a competing endogenous RNA to upregulate DAPK2 expression by sponging miR-22-3p, which consequently leads to cardiomyocyte apoptosis involved in the pathogenesis of DCM.