Cardioprotection of pharmacological postconditioning on myocardial ischemia/reperfusion injury

The pathological mechanisms and potential therapeutic drugs for myocardial ischemia reperfusion injury

BACKGROUND

Cardiovascular disease is the main cause of death and disability, with myocardial ischemia being the predominant type that poses a significant threat to humans. Reperfusion, an essential therapeutic approach, promptly reinstates blood circulation to the ischemic myocardium and stands as the most efficacious clinical method for myocardial preservation. Nevertheless, the restoration of blood flow associated with this process can potentially induce myocardial ischemia-reperfusion injury (MIRI), thereby diminishing the effectiveness of reperfusion and impacting patient prognosis. Therefore, it is of great significance to prevent and treat MIRI.

PURPOSE

MIRI is an important factor affecting the prognosis of patients, and there is no specific in-clinic treatment plan. In this review, we have endeavored to summarize its pathological mechanisms and therapeutic drugs to provide more powerful evidence for clinical application.

METHODS

A comprehensive literature review was conducted using PubMed, Web of Science, Embase, Medline and Google Scholar with a core focus on the pathological mechanisms and potential therapeutic drugs of MIRI.

RESULTS

Accumulated evidence revealed that oxidative stress, calcium overload, mitochondrial dysfunction, energy metabolism disorder, ferroptosis, inflammatory reaction, endoplasmic reticulum stress, pyroptosis and autophagy regulation have been shown to participate in the process, and that the occurrence and development of MIRI are related to plenty of signaling pathways. Currently, a range of chemical drugs, natural products, and traditional Chinese medicine (TCM) preparations have demonstrated the ability to mitigate MIRI by targeting various mechanisms.

CONCLUSIONS

At present, most of the research focuses on animal and cell experiments, and the regulatory mechanisms of each signaling pathway are still unclear. The translation of experimental findings into clinical practice remains incomplete, necessitating further exploration through large-scale, multi-center randomized controlled trials. Given the absence of a specific drug for MIRI, the identification of therapeutic agents to reduce myocardial ischemia is of utmost significance. For the future, it is imperative to enhance our understanding of the pathological mechanism underlying MIRI, continuously investigate and develop novel pharmaceutical agents, expedite the clinical translation of these drugs, and foster innovative approaches that integrate TCM with Western medicine. These efforts will facilitate the emergence of fresh perspectives for the clinical management of MIRI.

Baicalin-loaded Polydopamine modified ZIF-8 NPs inhibits myocardial ischemia/reperfusion injury in rats

Baicalin (BAN) has shown promise in alleviating myocardial ischemia/reperfusion (I/R) injury, yet its limited solubility and biocompatibility have hindered its application. Developing drug delivery systems is a promising strategy to enhance the therapeutic potential of BAN in the context of I/R injury. This study aims to prepare a BAN-loaded nanodrug system using polydopamine (PDA)-modified Zeolitic imidazolate framework-8 (ZIF-8) as a carrier, with the goal of improving BAN's mitigating effects on I/R injury. We prepared the BAN nanoparticles (NPs) system, PZB NPs, using ZIF-8 as the carrier. The system was characterized in terms of morphology, particle size, zeta potential, and X-ray diffraction (XRD). We assessed the cytotoxicity of PZB NPs in H9c2 cells, investigated its effects and mechanisms in H/R-induced H9c2 cells, and evaluated its ability to alleviate myocardial I/R injury in rats. PZB NPs exhibited good dispersion, with a BAN loading efficiency of 26.43 ± 1.55%, a hydrated particle size of 102.21 ± 1.19 nm, and a zeta potential of -24.84 ± 0.07 mV. It displayed slow and sustained drug release in an acidic environment (pH 5.5). In vitro studies revealed that PZB NPs was non-cytotoxic and significantly enhanced the recovery of H/R injury H9c2 cell viability. PZB NPs suppressed cell apoptosis, activated the Nrf2/HO-1 pathway, and cleared ROS. In vivo study demonstrated that PZB NPs significantly reduced infarct size, ameliorated fibrosis and improved heart function. The PZB NPs markedly enhances BAN's ability to alleviate I/R injury, both in vitro and in vivo, offering a promising drug delivery system for clinical applications.

A novel anti-inflammatory strategy for myocardial ischemia-reperfusion in rats with cinnamamide derivative compound 7

Reperfusion after myocardial ischemia would aggravate myocardial structural and functional damage, known as myocardial ischemia-reperfusion (MI/R) injury. Cinnamamide derivatives have been reported to exert cardioprotective effects, and we have previously reported that compound 7 played a role in cardioprotection against MI/R via anti-inflammatory effect. However, exact mechanism underlying such beneficial action of compound 7 is still unclear. The protective effect of compound 7 was determined in H9c2 cells under H2O2 stimulation with or without nigerin (NLRP3 activator). Electrocardiogram, echocardiography, myocardial infarction size, histopathology and serum biochemical assay were performed in MI/R rats. Metabolomics in vivo and mRNA or protein levels of NLRP3, ASC, cleaved caspase-1 and its downstream IL-18 and IL-1β were detected both in vitro and in vivo. Compound 7 significantly ameliorate H2O2-induced cardiomyocyte damage, which was supported by in vivo data determined by improved left ventricular systolic function and histopathological changes, reduced myocardial infarction area and cellular apoptosis in heart tissue. Cardiac differential metabolites demonstrated that compound 7 indeed altered the cardiac reprogramming of inflammation-related metabolites, which was evidenced by down-regulated cardiac inflammation by compound 7. Additionally, compound 7 alleviated myocardial injury by inhibiting the NLRP3 pathway rather than other members of the inflammasome both in vitro and in vivo, which was further evidenced by CETSA assay. Whereas, nigerin blocked the inhibitory activity of compound 7 against NLRP3. Cinnamamide derivative compound 7 ameliorated MI/R injury by inhibiting inflammation via NLRP3.

Crosstalk between ubiquitin ligases and ncRNAs drives cardiovascular disease progression

Cardiovascular diseases (CVDs) are multifactorial chronic diseases and have the highest rates of morbidity and mortality worldwide. The ubiquitin-proteasome system (UPS) plays a crucial role in posttranslational modification and quality control of proteins, maintaining intracellular homeostasis via degradation of misfolded, short-lived, or nonfunctional regulatory proteins. Noncoding RNAs (ncRNAs, such as microRNAs, long noncoding RNAs, circular RNAs and small interfering RNAs) serve as epigenetic factors and directly or indirectly participate in various physiological and pathological processes. NcRNAs that regulate ubiquitination or are regulated by the UPS are involved in the execution of target protein stability. The cross-linked relationship between the UPS, ncRNAs and CVDs has drawn researchers' attention. Herein, we provide an update on recent developments and perspectives on how the crosstalk of the UPS and ncRNAs affects the pathological mechanisms of CVDs, particularly myocardial ischemia/reperfusion injury, myocardial infarction, cardiomyopathy, heart failure, atherosclerosis, hypertension, and ischemic stroke. In addition, we further envision that RNA interference or ncRNA mimics or inhibitors targeting the UPS can potentially be used as therapeutic tools and strategies.

The low expression of miR-155 promotes the expression of SHP2 by inhibiting the activation of the ERK1/2 pathway and improves cell pyroptosis induced by I/R in mice

This study aims to explore the specific mechanism by which miR-155 regulates SHP2 expression in mouse ischemia-reperfusion (I/R) induced necroptosis. Various methods including cardiac ultrasound, TTC staining, Masson staining, TUNEL staining, and Western blotting were used to examine changes in the morphology and function of the rat left ventricle, myocardial fibrosis, as well as the expression of proteins related to tissue and cardiomyocyte necroptosis pathways. In vivo results showed that knockdown (KD) of miR-155 significantly improved cardiac ultrasound parameters (EF, FS, LVAW;d, and LVAW;s), reduced the myocardial infarction area, myocardial fibrosis, and cell apoptosis in I/R mice, upregulated cardiac SHP2 protein expression, and other proteins including p-ERK1/2, NLRP3, GSDMD, caspase-3, caspase-4, and caspase-11 were also significantly decreased. In vitro experiments showed that compared with the SHP2 WT miR-155 KD group, SHP2 protein expression was significantly increased in the SHP2 WT miR-155 KD group, while the expression of other proteins was significantly reduced, consistent with in vivo results. MiR-155 can regulate ERK1/2 and NLRP3 through SHP2. After adding the ERK1/2 inhibitor U0126 to cardiomyocytes from SHP2 KO mice, it was found that the expression of proteins other than SHP2 significantly decreased compared to SHP2 KO cells without the inhibitor. In summary, low expression of miR-155 promoted the expression of SHP2 and improved mouse I/R-induced necroptosis by inhibiting the activation of the ERK1/2 pathway.

Ramelteon alleviates myocardial ischemia/reperfusion injury (MIRI) through Sirt3--dependent regulation of cardiomyocyte apoptosis

Reperfusion stands as a pivotal intervention for ischemic heart disease. However, the restoration of blood flow to ischemic tissue always lead to further damage, which is known as myocardial ischemia/reperfusion injury (MIRI). Ramelteon is an orally administered drug used to improve sleep quality, which is famous for its high bioadaptability and absence of notable addictive characteristics. However, the specific mechanism by which it improves MIRI is still unclear. Sirtuin-3 (Sirt3), primarily located in mitochondria, is crucial in mitigating many cardiac diseases, including MIRI. Based on the structure of Sirt3, we simulated molecular docking and identified several potential amino acid binding sites between it and ramelteon. Therefore, we propose a hypothesis that ramelteon may exert cardioprotective effects by activating the Sirt3 signaling pathway. Our results showed that the activation levels and expression level of Sirt3 were significantly decreased in MIRI tissue and H2O2 stimulated H9C2 cells, while ramelteon treatment upregulated Sirt3 activity and expression. After treat with 3-TYP, a classic Sirt3 activity inhibitor, we constructed myocardial ischemia/reperfusion surgery in vivo and induced H9C2 cells with H2O2 in vitro. The results showed that the myocardial protection and anti-apoptotic effects of ramelteon were antagonized by 3-TYP, indicating that the activation of Sirt3 is a key mechanism for ramelteon to exert myocardial protection. In summary, our results confirm a novel mechanism by which ramelteon improves MIRI by activating Sirt3 signaling pathway, providing strong evidence for the treatment of MIRI with ramelteon.

Edgeworthia gardneri (Wall.) Meisn. Ethanolic Extract Attenuates Endothelial Activation and Alleviates Cardiac Ischemia-Reperfusion Injury

Endothelial pro-inflammatory activation is pivotal in cardiac ischemia-reperfusion (I/R) injury pathophysiology. The dried flower bud of Edgeworthia gardneri (Wall.) Meisn. (EG) is a commonly utilized traditional Tibetan medicine. However, its role in regulating endothelium activation and cardiac I/R injury has not been investigated. Herein, we showed that the administration of EG ethanolic extract exhibited a potent therapeutic efficacy in ameliorating cardiac endothelial inflammation (p < 0.05) and thereby protecting against myocardial I/R injury in rats (p < 0.001). In line with the in vivo findings, the EG extract suppressed endothelial pro-inflammatory activation in vitro by downregulating the expression of pro-inflammatory mediators (p < 0.05) and diminishing monocytes' firm adhesion to endothelial cells (ECs) (p < 0.01). Mechanistically, we showed that EG extract inhibited the nuclear factor kappa-B (NF-κB), c-Jun N-terminal kinase (JNK), extracellular regulated protein kinase (ERK), and p38 mitogen-activated protein kinase (MAPK) signaling pathways to attenuate EC-mediated inflammation (p < 0.05). Collectively, for the first time, this study demonstrated the therapeutic potential of EG ethanolic extract in alleviating I/R-induced inflammation and the resulting cardiac injury through its inhibitory role in regulating endothelium activation.

[D-Ala2, D-Leu5]-enkephalin (DADLE) provides protection against myocardial ischemia reperfusion injury by inhibiting Wnt/β-Catenin pathway

BACKGROUND

Acute myocardial infarction is one of the leading causes of death worldwide. Myocardial ischemia reperfusion (MI/R) injury occurs immediately after the coronary reperfusion and aggravates myocardial ischemia. Whether the Wnt/β-Catenin pathway is involved in the protection against MI/R injury by DADLE has not been evaluated. Therefore, the present study aimed to investigate the protective effect of DADLE against MI/R injury in a mouse model and to further explore the association between DADLE and the Wnt/β-Catenin pathway.

METHODS

Forty-four mice were randomly allocated to four groups: Group Control (PBS Control), Group D 0.25 (DADLE 0.25 mg/kg), Group D 0.5 (DADLE 0.5 mg/kg), and Group Sham. In the control and DADLE groups, myocardial ischemia injury was induced by occluding the left anterior descending coronary artery (LAD) for 45 min. PBS and DADLE were administrated, respectively, 5 min before reperfusion. The sham group did not go through LAD occlusion. 24 h after reperfusion, functions of the left ventricle were assessed through echocardiography. Myocardial injury was evaluated using TTC double-staining and HE staining. Levels of myocardial enzymes, including CK-MB and LDH, in the serum were determined using ELISA kits. Expression of caspase-3, TCF4, Wnt3a, and β-Catenin was evaluated using the Western blot assay.

RESULTS

The infarct area was significantly smaller in the DADLE groups than in the control group (P < 0.01). The histopathology score and serum levels of myocardial enzymes were significantly lower in the DADLE groups than in the control group (P < 0.01). DADLE significantly improved functions of the left ventricle (P < 0.01), decreased expression of caspase-3 (P < 0.01), TCF4 (P < 0.01), Wnt3a (P < 0.05), and β-Catenin (P < 0.01) compared with PBS.

CONCLUSIONS

The present study showed that DADLE protected the myocardium from MI/R through suppressing the expression of caspase-3, TCF4, Wnt3a, and β-Catenin and consequently improving functions of the left ventricle in I/R model mice. The TCF4/Wnt/β-Catenin signaling pathway might become a therapeutic target for MI/R treatment.

PA2G4/EBP1 ubiquitination by PRKN/PARKIN promotes mitophagy protecting neuron death in cerebral ischemia

Cerebral ischemia induces massive mitochondrial damage, leading to neuronal death. The elimination of damaged mitochondria via mitophagy is critical for neuroprotection. Here we show that the level of PA2G4/EBP1 (proliferation-associated 2G4) was notably increased early during transient middle cerebral artery occlusion and prevented neuronal death by eliciting cerebral ischemia-reperfusion (IR)-induced mitophagy. Neuron-specific knockout of Pa2g4 increased infarct volume and aggravated neuron loss with impaired mitophagy and was rescued by introduction of adeno-associated virus serotype 2 expressing PA2G4/EBP1. We determined that PA2G4/EBP1 is ubiquitinated on lysine 376 by PRKN/PARKIN on the damaged mitochondria and interacts with receptor protein SQSTM1/p62 for mitophagy induction. Thus, our study suggests that PA2G4/EBP1 ubiquitination following cerebral IR-injury promotes mitophagy induction, which may be implicated in neuroprotection.Abbreviations: AAV: adeno-associated virus; ACTB: actin beta; BNIP3L/NIX: BCL2 interacting protein 3 like; CA1: Cornu Ammonis 1; CASP3: caspase 3; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; DMSO: dimethyl sulfoxide; PA2G4/EBP1: proliferation-associated 2G4; FUNDC1: FUN14 domain containing 1; IB: immunoblotting; ICC: immunocytochemistry; IHC: immunohistochemistry; IP: immunoprecipitation; MCAO: middle cerebral artery occlusion; MEF: mouse embryonic fibroblast; OGD: oxygen-glucose deprivation; PRKN/PARKIN: parkin RBR E3 ubiquitin protein ligase; PINK1: PTEN induced kinase 1; RBFOX3/NeuN: RNA binding fox-1 homolog 3; SQSTM1/p62: sequestosome 1; TIMM23: translocase of inner mitochondrial membrane 23; TOMM20: translocase of outer mitochondrial membrane 20; TUBB: tubulin beta class I; WT: wild-type.

Mechanisms by which silencing long-stranded noncoding RNA KCNQ1OT1 alleviates myocardial ischemia/reperfusion injury (MI/RI)-induced cardiac injury via miR-377-3p/HMOX1

BACKGROUND

The key complication of myocardial infarction therapy is myocardial ischemia/reperfusion injury (MI/RI), and there is no effective treatment. The present study elucidates the mechanism of action of lncRNA KCNQ1OT1 in alleviating MI/RI and provides new perspectives and therapeutic targets for cardiac injury-related diseases.

METHODS

An ischemia/reperfusion (I/R) injury model of human adult cardiac myocytes (HACMs) was constructed, and the expression of KCNQ1OT1 and miR-377-3p was determined by RT‒qPCR. The levels of related proteins were detected by western blot analysis. Cell proliferation was detected by a CCK-8 assay, and cell apoptosis and ROS content were determined by flow cytometry. SOD and MDA expression as well as Fe2+ changes were detected by related analysis kits. The target binding relationships between lncRNA KCNQ1OT1 and miR-377-3p as well as between miR-377-3p and heme oxygenase 1 (HMOX1) were verified by a dual-luciferase reporter gene assay.

RESULTS

Myocardial ischemia‒reperfusion caused oxidative stress in HACMs, resulting in elevated ROS levels, increased Fe2+ levels, decreased cell viability, and increased LDH release (a marker of myocardial injury), and apoptosis. KCNQ1OT1 and HMOX1 were upregulated in I/R-induced myocardial injury, but the level of miR-377-3p was decreased. A dual-luciferase reporter gene assay indicated that lncRNA KCNQ1OT1 targets miR-377-3p and that miR-377-3p targets HMOX1. Inhibition of HMOX1 alleviated miR-377-3p downregulation-induced myocardial injury. Furthermore, lncRNA KCNQ1OT1 promoted the level of HMOX1 by binding to miR-377-3p and aggravated myocardial injury.

CONCLUSION

LncRNA KCNQ1OT1 aggravates ischemia‒reperfusion-induced cardiac injury via miR-377-3P/HMOX1.

Naringin improves post-ischemic myocardial injury by activation of KATP channels

Naringin (NRG) is a flavonoid with recognized cardioprotective effects. Then, it was investigated the cardioprotective mechanisms of NRG against ischemia-reperfusion (I/R) injury. The rats were pretreated for 7 days (v.o.) with NRG (25 mg/kg) or n-acetylcysteine (NAC, 100 mg/kg) and their isolated hearts were subjected to global ischemia (30 min) and reperfusion (60 min). Furthermore, isolated hearts were perfused with 5 μM NRG in the presence of 10 μM glibenclamide (GLI) and subjected to I/R protocol. In healthy ventricular cardiomyocyte, it was evaluated the acute effect of 5 μM NRG on the GLI sensitive current. The results showed that NRG pretreatment restored the cardiac function and electrocardiogram (ECG) alterations induced by I/R injury, decreasing arrhythmia scores and the occurrence of severe arrhythmias. Lactate dehydrogenase and infarct area were decreased while superoxide dismutase (SOD), catalase and citrate synthase activities increased. Expression of SOD CuZn and SOD Mn not was altered. NRG treatment decreased reactive oxygen species (ROS) generation and lipid peroxidation without alter sulfhydryl groups and protein carbonylation. Also, NRG (5 μM) increased the glibenclamide sensitive current in isolated cardiomyocytes. In isolated heart, the cardioprotection of NRG was significantly reduced by GLI. Furthermore, NRG promoted downregulation of Bax expression and Bax/Bcl-2. Histopathological analysis showed that NRG decreased cell edema, cardiomyocytes and nucleus diameter. Thus, NRG has a cardioprotective effect against cardiac I/R injury which is mediated by its antioxidant and antiapoptotic actions and KATP channels activation.

Four- to seven-year follow-up of pharmacological postconditioning with mangafodipir as an adjunct to primary PCI in ST-segment elevation myocardial infarction

INTRODUCTION

Adverse left ventricular remodelling (AR) develops over time in approximately 30% of patients with a history of coronary artery disease. AR manifests as a structural change in the left ventricle (LV) in terms of increased volumes and reduced left ventricular ejection fraction (LVEF). Manganese dipyridoxyl diphosphate (mangafodipir) has demonstrated interesting cardioprotective features in acute myocardial ischaemia. Pharmacological postconditioning (PP) with mangafodipir as an adjunct to primary percutaneous coronary intervention may possibly reduce the development of AR over time in ST-elevation myocardial infarction (STEMI). The aim of this 4-7-year follow-up study is to investigate the potential benefits of PP with mangafodipir in STEMI patients.

METHOD

Thirteen out of the initial 20 patients that were included in the primary study of Karlsson et al. were followed up between April and June 2017. The study group underwent review of the hospital records, a clinical examination with ECG and blood sample analysis before cardiac magnetic resonance examination of the patient. LVEF, left ventricular diastolic volume, left ventricular end systolic volume, LV mass and myocardial strain in all directions were computed.

RESULTS

The PP group showed a decrease in LV volume, mass and higher LVEF at follow-up (p < 0.05) while the individual response of the placebo group showed features that are seen in AR. Although there was no difference in myocardial strain, measurement for the PP-group was higher in absolute terms.

CONCLUSION

Pharmacological postconditioning with mangafodipir in STEMI demonstrated cardioprotective features compared to the placebo group at follow-up. This article is protected by copyright. All rights reserved.

Effects of daidzein on rat ovary against ischemia-reperfusion

PURPOSE

Our aim was to investigate protective effects of daidzein treatment on ischemia-reperfusion (I/R) injury-induced ovarian tissue by immunohistochemical techniques.

METHODS

Thirty Sprague Dawley female rats were categorized into three groups as sham, I/R group, and I/R+daidzein groups. Bloods were analyzed for malondialdehyde (MDA), glutathione peroxidase (GSH), and myeloperoxidase (MPO), and ovaries were processed for histological tissue protocol.

RESULTS

Both MDA and MPO values were increased in I/R group compared to sham and I/R+daidzein groups. GSH content was increased in I/R+daidzein group compared to I/R groups. In I/R group, theca and follicular cells were degenerated with apoptosis and dilatation and congestion, edema. In I/R+daidzein group, daidzein improved pathologies. In the I/R group, Bax expression was positive with follicular cells, granulosa cells and inflammatory cells. In the I/R+daidzein group, positive Bax reaction was observed in the epithelial, antral, and inflammatory cells. In I/R group, Bcl-2 reaction was in germinative epithelial cells, cells of antral follicle. In the I/R+daidzein group, Bcl-2 expression level was reduced after daidzein treatment.

CONCLUSIONS

After the I/R procedure, ovarian cells and follicles were degenerated with apoptosis and inflammation. After daidzein treatment, Bax and Bcl-2 signal were decreased. It was observed that daidzein stopped the apoptotic process.

The role of PI3K/AKT signaling pathway in myocardial ischemia-reperfusion injury

Myocardial ischemia has a high incidence and mortality rate, and reperfusion is currently the standard intervention. However, reperfusion may lead to further myocardial damage, known as myocardial ischemia/reperfusion injury (MIRI). There are currently no effective clinical treatments for MIRI. The PI3K/Akt signaling pathway is involved in cardiovascular health and disease and plays an important role in reducing myocardial infarct size and restoring cardiac function after MIRI. Activation of the PI3K/Akt pathway provides myocardial protection through synergistic upregulation of antioxidant, anti-inflammatory, and autophagy activities and inhibition of mitochondrial dysfunction and cardiomyocyte apoptosis. Many studies have shown that PI3K/Akt has a significant protective effect against MIRI. Here, we reviewed the molecular regulation of PI3K/Akt in MIRI and summarized the molecular mechanism by which PI3K/Akt affects MIRI, the effects of ischemic preconditioning and ischemic postconditioning, and the role of related drugs or activators targeting PI3K/Akt in MIRI, providing novel insights for the formulation of myocardial protection strategies. This review provides evidence of the role of PI3K/Akt activation in MIRI and supports its use as a therapeutic target.

Klf6 aggravates myocardial ischemia/reperfusion injury by activating Acsl4-mediated ferroptosis

Ferroptosis is closely related to myocardial ischemia/reperfusion (I/R) damage. Kruppel-like factor 6 (Klf6) can aggravate renal I/R injury. We aimed to elucidate the role of Klf6 in myocardial I/R damage as well as its potential mechanism. Myocardial I/R mice model and hypoxia/reoxygenation (H/R)-treated HL-1 cells were established. The levels of Fe2+ , MDA, lipid ROS, and ferroptosis-related proteins were measured for assessing ferroptosis. Infarct area, H&E staining, cardiac function, and cell viability were detected for evaluating myocardial injury. Immunohistochemistry, immunofluorescence, western blot, and RT-qPCR were applied for detecting the levels of related genes. The m6A modification of Klf6, as well as the relationships between Klf6 and Mettl3, Igf2bp2, or Acsl4 promoter, was evaluated using MeRIP, RNA immunoprecipitation, RNA pull-down, chromatin immunoprecipitation, and luciferase reporter assay accordingly.Klf6 protein and mRNA levels, as well as Klf6 m6A modification, were elevated in HL-1 cells subjected to H/R and in the heart tissues from I/R mice. In H/R-challenged HL-1 cells, the binding relationships between Klf6 mRNA and Igf2bp2 or Mettl3 were confirmed; moreover, Igf2bp2 or Mettl3 knockdown decreased the Klf6 level and inhibited Klf6 mRNA stability. Klf6 knockdown restrained H/R-triggered cell viability loss, improved I/R-induced myocardial injury, and inhibited ferroptosis in myocardial I/R damage models. Klf6 directly bound to the Acsl4 promoter and positively regulated its expression. Acsl4 overexpression compromised the Klf6 knockdown-generated protective effect in HL-1 cells.m6A modification-regulated Klf6 aggravated myocardial I/R damage through activating Acsl4-mediated ferroptosis, thereby providing one potential target for the treatment of myocardial I/R.

Low-intensity pulsed ultrasound of different intensities differently affects myocardial ischemia/reperfusion injury by modulating cardiac oxidative stress and inflammatory reaction

Introduction

The prevalence of ischemic heart disease has reached pandemic levels worldwide. Early revascularization is currently the most effective therapy for ischemic heart diseases but paradoxically induces myocardial ischemia/reperfusion (MI/R) injury. Cardiac inflammatory reaction and oxidative stress are primarily involved in the pathology of MI/R injury. Low-intensity pulsed ultrasound (LIPUS) has been demonstrated to reduce cell injury by protecting against inflammatory reaction and oxidative stress in many diseases, including cardiovascular diseases, but rarely on MI/R injury.

Methods

This study was designed to clarify whether LIPUS alleviates MI/R injury by alleviating inflammatory reaction and oxidative stress. Simultaneously, we have also tried to confirm which intensity of the LIPUS might be more suitable to ameliorate the MI/R injury, as well as to clarify the signaling mechanisms. MI/R and simulated ischemia/reperfusion (SI/R) were respectively induced in Sprague Dawley rats and human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs). LIPUS treatment, biochemical measurements, cell death assay, estimation of cardiac oxidative stress and inflammatory reaction, and protein detections by western blotting were performed according to the protocol.

Results

In our study, both in vivo and in vitro, LIPUS of 0.1 W/cm2 (LIPUS0.1) and 0.5 W/cm2 (LIPUS0.5) make no significant difference in the cardiomyocytes under normoxic condition. Under the hypoxic condition, MI/R injury, inflammatory reaction, and oxidative stress were partially ameliorated by LIPUS0.5 but were significantly aggravated by LIPUS of 2.5 W/cm2 (LIPUS2.5) both in vivo and in vitro. The activation of the apoptosis signal-regulating kinase 1 (ASK1)/c-Jun N-terminal kinase (JNK) pathway in cardiomyocytes with MI/R injury was partly rectified LIPUS0.5 both in vivo and in vitro.

Conclusion

Our study firstly demonstrated that LIPUS of different intensities differently affects MI/R injury by regulating cardiac inflammatory reaction and oxidative stress. Modulations on the ASK1/JNK pathway are the signaling mechanism by which LIPUS0.5 exerts cardioprotective effects. LIPUS0.5 is promising for clinical translation in protecting against MI/R injury. This will be great welfare for patients suffering from MI/R injury.

Is N-methylacetazolamide a possible new therapy against ischemia-reperfusion injury?

The increase of intracellular Ca2+ concentration, produced principally by its influx through the L-type Ca2+ channels, is one of the major contributors to the ischemia-reperfusion injury. The inhibition of those channels in different experimental models was effective to ameliorate the post-ischemic damage. However, at a clinical level, the results were contradictory. Recent results of our group obtained in an ¨ex vivo¨ heart model demonstrated that a chemical derived from acetazolamide, the N-methylacetazolamide (NMA) protected the heart against ischemia-reperfusion injury, diminishing the infarct size and improving the post-ischemic recovery of myocardial function and mitochondrial dynamic. A significant inhibitory action on L-type Ca2+ channels was also detected after NMA treatment, suggesting this action as responsible for the beneficial effects on myocardium exerted by this compound. Although these results were promising, the effectiveness of NMA in the treatment of ischemic heart disease in humans as well as the advantages or disadvantages in comparison to the classic calcium antagonists needs to be investigated.

Postconditioning with Lactate-Enriched Blood for Reducing Lethal Reperfusion Injury in Humans

Ischemic myocardium cannot survive without reperfusion. However, reperfusion of the ischemic myocardium paradoxically induces myocyte death; this phenomenon is termed lethal reperfusion injury. To date, no effective approach has been demonstrated for ST-segment elevation myocardial infarction (STEMI) in clinical settings. Recently, we demonstrated a novel approach for cardioprotection, termed postconditioning with lactate-enriched blood (PCLeB). PCLeB comprises intermittent reperfusion and timely coronary injections of lactated Ringer's solution, which is implemented at the beginning of reperfusion. This approach is aimed at reducing lethal reperfusion injury via prolonging intracellular acidosis during the early period of reperfusion, compared with the original postconditioning protocol. Patients with STEMI treated using PCLeB have reported positive outcomes. This article represents an effort, with a perspective different from current insights, toward preventing lethal reperfusion injury, in light of the historical background of reperfusion injury research. PCLeB is considered the new approach for cardioprotection.

Exercise training and experimental myocardial ischemia and reperfusion: A systematic review and meta-analysis

Background

Despite the success of interventional coronary reperfusion strategies, morbidity and mortality from acute myocardial infarction are still substantial. Physical exercise is a well-recognized effective non-pharmacological therapy for cardiovascular diseases. Therefore, the objective of this systematic review was to analyze studies in animal models of ischemia-reperfusion in association with physical exercise protocols.

Search strategy

Articles published on the topic over a 13-year period (2010-2022) were searched in two databases (PubMed and Google Scholar) using the keywords exercise training, ischemia/reperfusion or ischemia reperfusion injury. Meta-analysis and quality assessment of the studies were performed using the Review Manager 5.3 program.

Results

From the 238 articles retrieved from PubMed and 200 from Google Scholar, after screening and eligibility assessment, 26 articles were included in the systematic review and meta-analysis. For meta-analysis comparing the group of previously exercised animals with the non-exercised animals and then submitted to ischemia-reperfusion, the infarct size was significantly decreased by exercise (p < 0.00001). In addition, the group exercised had increased heart-to-body weight ratio (p < 0.00001) and improved ejection fraction as measured by echocardiography (p < 0.0004) in comparison to non-exercised animals.

Conclusion

We concluded that the animal models of ischemia-reperfusion indicates that exercise reduce infarct size and preserve ejection fraction, associated with beneficial myocardial remodeling.

Integrating UPLC-Q-Exactive Orbitrap/MS, network pharmacology and experimental validation to reveal the potential mechanism of Tibetan medicine Rhodiola granules in improving myocardial ischemia-reperfusion injury

ETHNOPHARMACOLOGY RELEVANCE

Rhodiola granules (RG) is a traditional Tibetan medicine prescription that can be used to improve the symptoms of ischemia and hypoxia in cardiovascular and cerebrovascular diseases. However, there is no report on its use to improve myocardial ischemia/reperfusion (I/R) injury, and its potential active ingredients and mechanism against myocardial ischemia/reperfusion (I/R) injury remain unclear.

AIM OF THE STUDY

This study aimed to reveal the potential bioactive components and underlying pharmacological mechanisms of RG in improving myocardial I/R injury through a comprehensive strategy.

MATERIALS AND METHODS

UPLC-Q-Exactive Orbitrap/MS technology was used to analyze the chemical components of RG, the potential bioactive components and targets were tracked and predicted by the SwissADME and SwissTargetPrediction databases, and the core targets were predicted through the PPI network, as well the functions and pathways were determined by GO and KEGG analysis. In addition, the molecular docking and ligation of the anterior descending coronary artery-induced rat I/R models were experimentally validated.

RESULTS

A total of 37 ingredients were detected from RG, including nine flavones, ten flavonoid glycosides, one glycoside, eight organic acids, four amides, two nucleosides, one amino acid, and two other components. Among them, 15 chemical components, such as salidroside, morin, diosmetin, and gallic acid were identified as key active compounds. Ten core targets, including AKT1, VEGF, PTGS2, and STAT3, were discovered through the analysis of the PPI network constructed from 124 common potential targets. These possible targets were involved in the regulation of oxidative stress and HIF-1/VEGF/PI3K-Akt signaling pathways. Furthermore, molecular docking confirmed that the potential bioactive compounds in RG have good potential binding abilities to AKT1, VEGFA, PTGS2, STAT3, and HIF-1α proteins. Then, the animal experiments showed that RG could significantly improve the cardiac function of I/R rats, reduce the size of myocardial infarction, improve the myocardial structure, and reduce the degree of myocardial fibrosis, inflammatory cell infiltration, and myocardial cell apoptosis rate in I/R rats. In addition, we also found that RG could decrease the concentration of AGE, Ox-LDL, MDA, MPO, XOD, SDH, Ca²⁺, and ROS, and increase the concentration of Trx, TrxR1, SOD, T-AOC, NO, ATP, Na⁺k⁺-ATPase, Ca²⁺-ATPase, and CCO. Moreover, RG could significantly down-regulate the expressions of Bax, Cleaved-caspase3, HIF-1α, and PTGS2, as well up-regulate the expressions of Bcl-2, VEGFA, p-AKT1, and p-STAT3.

CONCLUSION

In summary, we revealed for the first time the potential active ingredients and mechanisms of RG for myocardial I/R injury therapy through a comprehensive research strategy. RG may synergistically improve myocardial I/R injury through anti-inflammatory, regulating energy metabolism, and oxidative stress, improving I/R-induced myocardial apoptosis, which may be related to the HIF-1/VEGF/PI3K-Akt signaling pathway. Our study provides new insights into the clinical application of RG and also provides a reference for the development and mechanism research of other Tibetan medicine compound preparations.

Blocking RIPK2 Function Alleviates Myocardial Ischemia/Reperfusion Injury by Regulating the AKT and NF-κB Pathways

OBJECTIVE

Inflammation and oxidation brought on by myocardial ischemia-reperfusion (MI/R) injury lead to cardiomyocyte apoptosis and necrosis. The receptor interacting serine/threonine kinase 2 (RIPK2) plays significant roles in oxidative stress and excessive inflammation. The purpose of this research is to examine the roles of RIPK2 in MI/R injury.

METHODS

The in vivo animal model was constructed by acute coronary I/R, and the in vitro cell model was established by oxygen and glucose deprivation/reperfusion (OGD/R)-stimulated cardiomyocyte injury. RIPK2 expression was examined using qRT-PCR and Western blot. CCK-8 was proposed as a method for detecting cell proliferation. ELISA was utilized to measure inflammatory cytokines (TNF-α, IL-6, and IL-1β) and myocardial injury indicators (CK-MB, Mb, cTnI, and LDH). The levels of MDA and ROS were determined by the kit and fluorescent probe. H&E was conducted to assess MI/R injury after silencing of RIPK2.

RESULTS

In MI/R rats and OGD/R-treated H9C2 cardiomyocytes, RIPK2 was overexpressed at both the mRNA and protein levels. RIPK2 inhibition promoted cell proliferation while inhibiting apoptosis, as evidenced by decreased TUNEL-positive cells and cleaved caspase-3. RIPK2 inhibition reduced MDA and ROS levels, as well as the contents of inflammatory factors. RIPK2 silencing reduced CK-MB, Mb, cTnI, and LDH levels in rat serum and alleviated MI/R injury. Furthermore, RIPK2 inhibition increased p-AKT while decreasing NF-B p-p65 expression.

CONCLUSION

Silencing of RIPK2 reduced apoptosis, proinflammatory factors, and oxidative stress in MI/R by activating AKT and suppressing NF-κB signals, suggesting a potential therapeutic strategy for MI/R injury.

Local injection of bone-marrow derived mesenchymal stromal cells alters a molecular expression profile of a contact frostbite injury wound and improves healing in a rat model

INTRODUCTION

Frostbite is a traumatic injury of the tissues upon low temperature environment exposure, which is characterized by direct cell injury due to freezing-thawing followed by development of an acute inflammatory process. Severe frostbite can lead to necrosis of soft tissues and loss of a limb. Mesenchymal stromal cells (MSCs) have a unique ability to modulate pathogenic immune response by secretion of paracrine factors, which suppress inflammation and mediate more efficient tissue regeneration. It should be noted that potential of stem cell therapy for frostbite injury treatment has not been investigated so far. Here, we evaluated a healing capacity of bone-marrow derived MSCs for the treatment of contact frostbite injury wound in a rat model.

METHODS

Cold-contact injury in a Wistar rat model was induced by 1-minute tight application of the cooled probe (-196 ⁰C) to the skin surface of the left hip. Rat bone marrow MSCs were phenotypically characterized and used for local injections into non-damaged tissues surrounding the wound of animals from the experimental group. The second group of rats was treated in the same manner with 1 mL of isotonic sodium chloride solution. Analysis of cytokine and growth factor expression profile in сold-contact injury wounds was performed on days 5, 9, and 16 using immunoblotting and enzyme-linked immunosorbent assay. Animal recovery in MSC-treated and vehicle-treated groups was evaluated by several criteria including body weight recording, determination of eschar desquamation and re-epithelialization terms, assessment of wound closure kinetics, and histological scoring of the wounds on day 23.

RESULTS

It turned out that a single subcutaneous administration of MSCs around the wound site resulted in elevated expression of pro-survival and pro-angiogenic VEGF-A and PDGF and 3-5-fold decrease in pro-inflammatory IL-1β as compared with the frostbite wound treated with a vehicle. Moreover, treatment with MSCs caused accelerated wound re-epithelialization (p < 0.05) as well as a better histological score of the MSC-treated wounds.

CONCLUSIONS

Thus, our data suggested that the use of MSCs is a promising therapeutic strategy for the treatment of cold-induced injury wounds.

MiR-144-5p/CCL12 Signaling Axis Modulates Ischemic Preconditioning-Mediated Cardio-protection by Reducing Cell Viability, Enhancing Cell Apoptosis, Fibrosis, and Pyroptosis

Ischemic postconditioning (IPost) represents short periods of nonlethal ischemia-reperfusion performed at the onset of reperfusion. Studies have shown that IPost involves various biological processes such as cell proliferation, apoptosis, and pyroptosis and can activate complex signaling pathways. CCL12 is a critical mediator in the inflammatory process after tissue injury. In the present study, we examined the potential actions of CCL12-mediated signaling pathways in cardioprotection after IPost using a cardiomyocyte model. By applying the bioinformatics analysis, we found that CCL12 was upregulated in the rat heart tissues after I/R injury, and the expression level of CCL12 was restored in rats with IPost. The in vitro studies showed that CCL12 and CCR2 expression levels were upregulated in the hypoxia/reoxygenation (H/R)-induced H9C2 cells, which was attenuated in the H/R + hypoxia post-conditioning (PostC) group. The functional assays showed that H/R treatment reduced cell viability, increased cell apoptosis, and promoted fibrosis and pyroptosis of H9C2 cells, which was attenuated in the H/R + PostC group. Overexpression of CCL12 impaired the protective action of hypoxia post-conditioning in the H9C2 cells. Further mechanistic studies showed that miR-144-5p could directly target the 3' untranslated region of CCL12. Overexpression of miR-144-5p markedly repressed the expression levels of CCL12 and CCR2 in H9C2 cells, while miR-144-5p inhibition had the opposite effects. Furthermore, the inhibition of miR-144-5p reduced the cell viability, increased cell apoptosis, and enhanced fibrosis and pyroptosis of H9C2 cells after H/R or H/R + PostC treatment. In conclusion, CCL12 was downregulated in cardiomyocytes following ischemic postconditioning, and CCL12 overexpression impaired the cardioprotective actions of ischemic postconditioning by reducing cell viability, enhancing cell apoptosis, fibrosis, and pyroptosis. Further mechanistic evidence revealed that CCL12 was a direct target of miR-144-5p, and miR-144-5p/CCL12/CCR2 signaling may represent a critical pathway in mediating the cardioprotective effects of ischemic postconditioning.

Amelioration of myocardial ischemia/reperfusion injury in diabetes: A narrative review of the mechanisms and clinical applications of dexmedetomidine

Mechanisms contributing to the pathogenesis of myocardial ischemia-reperfusion (I/R) injury are complex and multifactorial. Many strategies have been developed to ameliorate myocardial I/R injuries based on these mechanisms. However, the cardioprotective effects of these strategies appear to diminish in diabetic states. Diabetes weakens myocardial responses to therapies by disrupting intracellular signaling pathways which may be responsible for enhancing cellular resistance to damage. Intriguingly, it was found that Dexmedetomidine (DEX), a potent and selective α2-adrenergic agonist, appears to have the property to reverse diabetes-related inhibition of most intervention-mediated myocardial protection and exert a protective effect. Several mechanisms were revealed to be involved in DEX’s protection in diabetic rodent myocardial I/R models, including PI3K/Akt and associated GSK-3β pathway stimulation, endoplasmic reticulum stress (ERS) alleviation, and apoptosis inhibition. In addition, DEX could attenuate diabetic myocardial I/R injury by up-regulating autophagy, reducing ROS production, and inhibiting the inflammatory response through HMGB1 pathways. The regulation of autonomic nervous function also appeared to be involved in the protective mechanisms of DEX. In the present review, the evidence and underlying mechanisms of DEX in ameliorating myocardial I/R injury in diabetes are summarized, and the potential of DEX for the treatment/prevention of myocardial I/R injury in diabetic patients is discussed.

Targeting Nrf2 in ischemia-reperfusion alleviation: From signaling networks to therapeutic targeting

The nuclear factor erythroid 2-related factor 2 (Nrf2) is a master regulator of redox balance and it responds to various cell stresses that oxidative stress is the most well-known one. The Nrf2 should undergo nuclear translocation to exert its protective impacts and decrease ROS production. On the other hand, ischemic/reperfusion (I/R) injury is a pathological event resulting from low blood flow to an organ and followed by reperfusion. The I/R induces cell injury and organ dysfunction. The present review focuses on Nrf2 function in alleviation of I/R injury. Stimulating of Nrf2 signaling ameliorates I/R injury in various organs including lung, liver, brain, testis and heart. The Nrf2 enhances activity of antioxidant enzymes to reduce ROS production and prevent oxidative stress-mediated cell death. Besides, Nrf2 reduces inflammation via decreasing levels of pro-inflammatory factors including IL-6, IL-1β and TNF-α. Nrf2 signaling is beneficial in preventing apoptosis and increasing cell viability. Nrf2 induces autophagy to prevent apoptosis during I/R injury. Furthermore, it can interact with other molecular pathways including PI3K/Akt, NF-κB, miRNAs, lncRNAs and GSK-3β among others, to ameliorate I/R injury. The therapeutic agents, most of them are phytochemicals such as resveratrol, berberine and curcumin, induce Nrf2 signaling in I/R injury alleviation.

Nerve growth factor and post-infarction cardiac remodeling

The prevalence of sudden death from chronic heart failure and cardiac arrhythmias caused by myocardial infarction is a complex problem in cardiology. Post-infarction cardiac remodeling occurs after myocardial infarction. This compensatory-adaptive reaction, regulated by mechanical, neurohumoral and genetic factors, includes the structural and functional changes of cardiomyocytes, stromal elements and extracellular matrix, geometry and architectonics of the left ventricular cavity. Adverse left ventricular remodeling is associated with heart failure and increased mortality. The concept of post-infarction cardiac remodeling is an urgent problem, since the mechanisms of development and progression of adverse post-infarction changes in the myocardium are completely unexplored. In recent years, the scientist attention has been focused on neurotrophic factors involved in the sympathetic nervous system and the vascular system remodeling after myocardial infarction. Nerve growth factor (NGF) is a protein from the neurotrophin family that is essential for the survival and development of sympathetic and sensory neurons, which also plays an important role in vasculogenesis. Acute myocardial infarction and heart failure are characterized by changes in the expression and activity of neurotrophic factors and their receptors, affecting the innervation of the heart muscle, as well as having a direct effect on cardiomyocytes, endothelial and smooth muscle vascular cells. The identification of the molecular mechanisms involved in the interactions between cardiomyocytes and neurons, as well as the study of the effects of NGF in the cardiovascular system, will improve understanding of the cardiac remodeling mechanism. This review summarizes the available scientific information (2019–2021) about mechanisms of the link between post-infarction cardiac remodeling and NGF functions.

Gradual Versus Abrupt Reperfusion During Primary Percutaneous Coronary Interventions in ST‐Segment–Elevation Myocardial Infarction (GUARD)

Background

Intramyocardial edema and hemorrhage are key pathological mechanisms in the development of reperfusion‐related microvascular damage in ST‐segment–elevation myocardial infarction. These processes may be facilitated by abrupt restoration of intracoronary pressure and flow triggered by primary percutaneous coronary intervention. We investigated whether pressure‐controlled reperfusion via gradual reopening of the infarct‐related artery may limit microvascular injury in patients undergoing primary percutaneous coronary intervention.

Methods and Results

A total of 83 patients with ST‐segment–elevation myocardial infarction were assessed for eligibility and 53 who did not meet inclusion criteria were excluded. The remaining 30 patients with totally occluded infarct‐related artery were randomized to the pressure‐controlled reperfusion with delayed stenting (PCRDS) group (n=15) or standard primary percutaneous coronary intervention with immediate stenting (IS) group (n=15) (intention‐to‐treat population). Data from 5 patients in each arm were unsuitable to be included in the final analysis. Finally, 20 patients undergoing primary percutaneous coronary intervention who were randomly assigned to either IS (n=10) or PCRDS (n=10) were included. In the PCRDS arm, a 1.5‐mm balloon was used to achieve initial reperfusion with thrombolysis in myocardial infarction grade 3 flow and, subsequently, to control distal intracoronary pressure over a 30‐minute monitoring period (MP) until stenting was performed. In both study groups, continuous assessment of coronary hemodynamics with intracoronary pressure and Doppler flow velocity was performed, with a final measurement of zero flow pressure (primary end point of the study) at the end of a 60‐minute MP. There were no complications associated with IS or PCRDS. PCRDS effectively led to lower distal intracoronary pressures than IS over 30 minutes after reperfusion (71.2±9.37 mm Hg versus 90.13±12.09 mm Hg, P =0.001). Significant differences were noted between study arms in the microcirculatory response over MP. Microvascular perfusion progressively deteriorated in the IS group and at the end of MP, and hyperemic microvascular resistance was significantly higher in the IS arm as compared with the PCDRS arm (2.83±0.56 mm Hg.s.cm −1 versus 1.83±0.53 mm Hg.s.cm −1 , P =0.001). The primary end point (zero flow pressure) was significantly lower in the PCRDS group than in the IS group (41.46±17.85 mm Hg versus 76.87±21.34 mm Hg, P =0.001). In the whole study group (n=20), reperfusion pressures measured at predefined stages in the early reperfusion period showed robust associations with zero flow pressure values measured at the end of the 1‐hour MP (immediately after reperfusion: r =0.782, P <0.001; at the 10th minute: r =0.796, P <0.001; and at the 20th minute: r =0.702, P =0.001) and peak creatine kinase MB level (immediately after reperfusion: r =0.653, P =0.002; at the 10th minute: r =0.597, P =0.007; and at the 20th minute: r =0.538, P =0.017). Enzymatic myocardial infarction size was lower in the PCRDS group than in the IS group with peak troponin T (5395±2991 ng/mL versus 8874±1927 ng/mL, P =0.006) and creatine kinase MB (163.6±93.4 IU/L versus 542.2±227.4 IU/L, P <0.001).

Conclusions

In patients with ST‐segment–elevation myocardial infarction, pressure‐controlled reperfusion of the culprit vessel by means of gradual reopening of the occluded infarct‐related artery (PCRDS) led to better‐preserved coronary microvascular integrity and smaller myocardial infarction size, without an increase in procedural complications, compared with IS.

Registration

URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02732080.

L-Borneol 7-O-[β-D-Apiofuranosyl-(1 → 6)]-β-D-Glucopyranoside Alleviates Myocardial Ischemia-Reperfusion Injury in Rats and Hypoxic/Reoxygenated Injured Myocardial Cells via Regulating the PI3K/AKT/mTOR Signaling Pathway

Ischemia/reperfusion (I/R) is a primary cause of morbidity and mortality in acute myocardial infarction (AMI). L-Borneol 7-O-[β-D-apiofuranosyl-(1→6)]-β-D-glucopyranoside (LBAG), extracted from the Radix Ophiopogonis, is the main bioactive component that may be exerting cardiovascular protection in AMI. The purpose was to examine the effects of LBAG on myocardial I/R injury (MIRI) in rats and H9c2 cells treated with hypoxia/reoxygenation (H/R). MIRI was induced through the combination of ischemia with reperfusion for 30 min and 24 h, respectively. LBAG was administered 7 days before vascular ligation. Myocardial function was detected by an electrocardiograph, histological, TTC, and TUNEL staining analyses. The influences of LBAG on the content concentration of cardiac enzymes in the serum were measured by ELISA. Moreover, H9c2 cells were exposed to LBAG or combined with AKT inhibitor (perifosine) and then exposed to H/R for simulating the cardiac injury process. Afterward, cell viability, LDH, CD-KM release, apoptosis, and autophagy were evaluated by CCK-8 and ELISA assays, flow cytometry, TUNEL, and immunofluorescence staining, respectively. Additionally, the proteins of apoptosis, autophagy, and PI3K/mTOR pathway were determined by western blotting. In I/R rats, LBAG pretreatment significantly ameliorated cardiac function, as illustrated by reducing the infarct size, myocardial autophagy, and apoptosis levels. In H/R-induced H9c2 cells, LBAG pretreatment significantly decreased cell apoptosis, LC3 II/I, and Beclin 1 levels, elevated the Bcl-2 levels, attenuated LDH, and CD-KM production. Moreover, LBAG pretreatment markedly increased the PI3K/mTOR pathway activation, and the protective influences of LBAG were partly abolished with the AKT inhibitor perifosine treatment. These findings demonstrated the protective functions of LBAG on I/R by regulating apoptosis and autophagy in vitro and in vivo by activating the PI3K/mTOR pathway.

Honokiol Provides Cardioprotection from Myocardial Ischemia/Reperfusion Injury (MI/RI) by Inhibiting Mitochondrial Apoptosis via the PI3K/AKT Signaling Pathway

Background

Myocardial injury refers to a major complication that occurs in myocardial ischemia/reperfusion injury (MI/RI). Honokiol is a well-recognized active compound extracted from the traditional Chinese herb known as Magnolia officinalis and is utilized in treating different vascular diseases. This research is aimed at examining whether Honokiol might alleviate myocardial injury in an MI/RI model.

Methods

Seventy-eight male C57BL/6 mice were categorized randomly into three cohorts including the Sham operation (Sham) cohort, the MI/RI cohort (Con), and the Honokiol cohort (n = 26 for each cohort). The mice in the Honokiol cohort were treated with Honokiol before MI/RI surgery (0.2 mg/kg/day for 14 days, intraperitoneal), while the mice in the Con cohort were given an intraperitoneal injection with an equivalent volume of vehicle (DMSO) daily in 14 days prior to exposure to MI/RI. After the surgery, creatine kinase- (CK-) MB and cardiac troponin T (cTnT) levels, as well as the infarct area, were measured to assess the degree of myocardial damage. Apoptotic levels were detected using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining. Electron microscopy was utilized to identify mitochondrial damage. Lastly, the expression levels of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), cleaved caspase-9, cytochrome C (Cyt-C), B cell lymphoma/leukemia-2 (Bcl-2), B cell lymphoma/leukemia-2 associated X (Bax), AKT, p-AKT, PI3K, and p-PI3K were analyzed utilizing western blotting.

Results

Honokiol can reduce the MI/RI-induced cTnT and CK-MB levels, apoptosis index, and mitochondrial swelling in cardiomyocytes via activating the PI3K/AKT signaling pathway.

Conclusion

Honokiol provides cardiac protection from MI/RI by suppressing mitochondrial apoptosis through the PI3K/AKT signaling pathway.

Hypercholesterolemia attenuates cardioprotection of ischemic preconditioning and postconditioning with α7 nicotinic acetylcholine receptor agonist by enhancing inflammation and inhibiting the PI3K/Akt/eNOS pathway

The present study aimed to evaluate the effects of hypercholesterolemia on cardioprotection of ischemic preconditioning and α7 nicotinic acetylcholine receptor (α7nAChR) agonist postconditioning and explore the potential mechanisms that hypercholesterolemia affected their cardioprotection. Hypercholesterolemic and normal rats were divided into the four groups that received the following treatments: i) Hypercholesterolemic control and normal control groups; ii) hypercholesterolemic ischemia/reperfusion (HI) and normal ischemia/reperfusion (NI) groups; iii) hypercholesterolemic ischemic preconditioning (HIPC) and normal ischemic preconditioning (NIPC) groups; and iv) hypercholesterolemic PNU282987 postconditioning (HPNU) and normal PNU282987 postconditioning (NPNU) groups. Serum lactate dehydrogenase (LDH), creatine kinase isoenzyme MB (CK-MB), cardiac troponin I (cTnI), tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) levels after ischemia/reperfusion were assayed. Furthermore, infarct size and expression levels of Akt, phosphorylated (p)-Akt and endothelial nitric oxide synthase (eNOS) in ischemic myocardium were assessed. Compared with the NI group, serum LDH, CK-MB, cTnI, TNF-α and IL-6 levels and infarct size were significantly decreased, and myocardial p-Akt/Akt and eNOS/GAPDH ratios were significantly increased in the NIPC and NPNU groups. Compared with the HI group, serum CK-MB, cTnI, TNF-α and IL-6 levels and infarct size were significantly decreased in the HIPC group; however, myocardial p-Akt/Akt and eNOS/GAPDH ratios did not significantly change in the HIPC group. Furthermore, there were no significant difference between the HI and HPNU groups in serum LDH, CK-MB, cTnI, TNF-α and IL-6 levels, infarct size, myocardial p-Akt/Akt and eNOS/GAPDH ratios. In conclusion, hypercholesterolemia could aggravate myocardial ischemia/reperfusion injury, attenuate cardioprotection of ischemic preconditioning and eliminate cardioprotection from α7nAChR agonist postconditioning by enhancing inflammation and inhibiting PI3K/Akt/eNOS pathway.

Catalpol protects AC16 cells from hypoxia/reoxygenation injury by regulating the miR-22-3p/DPP4 axis

Catalpol (CA) is widely used in the protection of cardiomyocytes. Nevertheless, the mechanism of CA in alleviating ischemia-reperfusion-induced injury of cardiomyocytes remains unclear. Human cardiomyocyte AC16 cells were subjected to hypoxia/reoxygenation (H/R) injury. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis were applied to detect tumor necrosis factor-alpha (TNF-α) mRNA, interleukin-6 (IL-6) mRNA, interleukin-1beta (IL-1β) mRNA, microRNA-22-3p (miR-22-3p), dipeptidyl peptidase 4 (DPP4) mRNA, and DPP4 protein expressions. The cell viability and apoptosis were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry, respectively. Lactate dehydrogenase (LDH) and creatine kinase (CK-MB) were examined by enzyme-linked immunosorbent assay (ELISA) kits. A dual-luciferase reporter gene assay was performed to confirm the binding sequence between miR-22-3p and DPP4 mRNA 3'-untranslated region (3'UTR). CA promoted the viability and reduced cell apoptosis of AC16 cells and repressed the release of inflammatory cytokines TNF-α, IL-6, and IL-1β, and inhibited the leakage of myocardial injury markers LDH and CK-MB. Furthermore, CA enhanced the expression of miR-22-3p in cardiomyocytes, and DPP4 was validated to be the target gene of miR-22-3p. The inhibition of miR-22-3p and augmentation of DPP4 reversed the above effects of CA. CA protects A16 cells from H/R injury by regulating the miR-22-3p/DPP4 axis.

Revealing Calcium Signaling Pathway as Novel Mechanism of Danhong Injection for Treating Acute Myocardial Infarction by Systems Pharmacology and Experiment Validation

Introduction: Danhong injection (DHI) is a traditional Chinese medicine preparation commonly used in the clinical treatment of acute myocardial infarction (AMI). In this study, the active components of DHI and its mechanism in the treatment of AMI were investigated.

Methods: The chemical components of DHI were detected by the ultra-high-performance liquid chromatography-linear trap quadrupole-orbitrap-tandem mass spectrometry (UHPLC-LTQ-Orbitrap-MS/MS), and the targets and pathways of DHI in the treatment of AMI were analyzed by systems pharmacology, which was verified by molecular docking and animal experiments.

Results: A total of 12 active components of DHI were obtained, and 158 common targets of component and disease were identified by systems pharmacology. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis results showed that DHI is closely related to the calcium signaling pathway in the treatment of AMI. Molecular docking showed that the key target protein has good binding affinity to related compounds. The experimental results showed that compared with the model group, LVAWs, EF, and FS significantly (p < 0.05) increased in the DHI group. The percentage of myocardial infarction significantly (p < 0.01) decreased, both in the ventricular and total cardiac regions, and the pathological damage of myocardial tissue also decreased. In addition, the expression of the protein CaMK II decreased (p < 0.01) and the expression of SERCA significantly increased (p < 0.01).

Conclusion: This study revealed that ferulic acid, caffeic acid and rosmarinic acid could inhibit AMI by regulating PLB, CaMK II, SERCA, etc. And mechanistically, calcium signaling pathway was critically involved. Combination of systems pharmacology prediction with experimental validation may provide a scientific basis for in-depth clinical investigation of the material basis of DHI.

Mechanism of Action of Flavonoids of Oxytropis falcata on the Alleviation of Myocardial Ischemia–Reperfusion Injury

Oxytropis falcata Bunge is a plant used in traditional Tibetan medicine, with reported anti-inflammatory and antioxidants effects and alleviation of myocardial ischemia reperfusion injury (MIRI). However, the underlying mechanism against MIRI and the phytochemical composition of O. falcata are vague. One fraction named OFF1 with anti-MIRI activity was obtained from O. falcata, and the chemical constituents were identified by ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC–MS). The potential targets and signaling pathways involved in the action of O. falcata against MIRI were predicted by network pharmacology analysis, and its molecular mechanism on MIRI was determined by in vitro assays. The results revealed that flavonoids are the dominant constituents of OFF1. A total of 92 flavonoids reported in O. falcata targeted 213 potential MIRI-associated factors, including tumor necrosis factor (TNF), prostaglandin-endoperoxide synthase 2 (PTGS2), and the NF-κB signaling pathway. The in vitro assay on H9c2 cardiomyocytes subjected to hypoxia/reoxygenation injury confirmed that the flavonoids in OFF1 reduced myocardial marker levels, apoptotic rate, and the inflammatory response triggered by oxidative stress. Moreover, OFF1 attenuated MIRI by downregulating the ROS-mediated JNK/p38MAPK/NF-κB pathway. Collectively, these findings provide novel insights into the molecular mechanism of O. falcata in alleviating MIRI, being a potential therapeutic candidate.

Levosimendan Postconditioning Attenuates Cardiomyocyte Apoptosis after Myocardial Infarction

BACKGROUND

Levosimendan preconditioning has been shown to attenuate myocardial apoptosis in animal models. However, protective effects of levosimendan postconditioning against myocardial apoptosis following myocardial infarction (MI) have not been evaluated. Therefore, we investigated the effects of levosimendan postconditioning on myocardial apoptosis in MI rat models.

METHODS

In an anoxia/reoxygenation (A/R) model, H9c2 cells were pretreated with or without levosimendan postconditioning after which their apoptosis rates were assessed by flow cytometry, RT-qPCR, and western blot analyses. Then, postconditioning was performed with or without levosimendan in MI rat models. Myocardiocyte apoptosis was evaluated by echocardiography, TTC staining, TUNEL staining, immunohistochemical staining, RT-qPCR, and western blot analysis.

RESULTS

Levosimendan postconditioning inhibited H9c2 cell apoptosis in A/R models by elevating Bcl-2 while suppressing Caspase-3 and Bax at both mRNA and protein levels. Moreover, it improved cardiac functions and reduced the left ventricle infarction area in MI rat models. Compared to the MI control group, cardiomyocyte apoptosis rates in the levosimendan postconditioning group were low. The reduced cardiomyocyte apoptosis rates were associated with downregulation of Bax and Caspase-3 as well as with upregulation of Bcl-2 at mRNA and protein levels.

CONCLUSIONS

Levosimendan postconditioning of MI rat models protected against cardiomyocyte apoptosis, implying that it is a potential strategy for preventing cardiomyocyte apoptosis in the treatment of cardiac dysfunction following MI.

APPL1 ameliorates myocardial ischemia‑reperfusion injury by regulating the AMPK signaling pathway

Myocardial ischemia-reperfusion injury results in elevated reactive oxygen species (ROS) production and causes oxidative stress damage. Therefore, the current study aimed to investigate whether adaptor protein phosphotyrosine interacting with PH domain and leucine zipper 1 (APPL1) could induce the expression of antioxidant enzymes through AMP-activated protein kinase (AMPK) signaling in order to alleviate the injury caused by ischemia/hypoxia-reperfusion. Following induction of hypoxia-reoxygenation (H/R) injury in H9c2 cells, the liver kinase B1 (LKB1)/AMPK/acetyl-CoA carboxylase α (ACC) signaling pathway was investigated using western blot analysis, along with the detection of superoxide dismutase (SOD)2 and SOD3 expression. Additionally, cell viability was detected using a Cell Counting Kit-8 assay and ROS production was analyzed using ROS staining, whereas the expression levels of inflammatory mediators (TNF-α, monocyte chemoattractant protein 1 and IL-1β), apoptosis mediators [cleaved caspase-3, cleaved poly (ADP-ribose) polymerase and Bcl-2] and nuclear factor erythroid 2-related factor 2 signaling pathway-related proteins were detected via western blot analysis following overexpression of APPL1 alone or in combination with compound C treatment (an AMPK inhibitor). The results indicated that H/R induction upregulated the phosphorylation levels of LKB1, AMPK and ACC, and decreased the expression levels of APPL1 and SOD enzyme activities. APPL1 overexpression increased the phosphorylation levels of LKB1, AMPK and ACC, SOD enzyme activity and cell viability whereas the expression levels of proinflammatory mediators and proapoptotic mediators, and the levels of ROS production were markedly decreased when compared with H/R group with empty plasmid transfection. APPL overexpression-mediated effects were significantly abrogated by compound C. Taken together, the data indicated that APPL1 inhibited ROS production and H/R-induced myocardial injury via the AMPK signaling pathway. Therefore, APPL1 may serve as a potential therapeutic target for myocardial H/R injury.

Emerging Role of Mitophagy in the Heart: Therapeutic Potentials to Modulate Mitophagy in Cardiac Diseases

The normal function of the mitochondria is crucial for most tissues especially for those that demand a high energy supply. Emerging evidence has pointed out that healthy mitochondrial function is closely associated with normal heart function. When these processes fail to repair the damaged mitochondria, cells initiate a removal process referred to as mitophagy to clear away defective mitochondria. In cardiomyocytes, mitophagy is closely associated with metabolic activity, cell differentiation, apoptosis, and other physiological processes involved in major phenotypic alterations. Mitophagy alterations may contribute to detrimental or beneficial effects in a multitude of cardiac diseases, indicating potential clinical insights after a close understanding of the mechanisms. Here, we discuss the current opinions of mitophagy in the progression of cardiac diseases, such as ischemic heart disease, diabetic cardiomyopathy, cardiac hypertrophy, heart failure, and arrhythmia, and focus on the key molecules and related pathways involved in the regulation of mitophagy. We also discuss recently reported approaches targeting mitophagy in the therapy of cardiac diseases.

LncRNA PVT1 Knockdown Ameliorates Myocardial Ischemia Reperfusion Damage via Suppressing Gasdermin D-Mediated Pyroptosis in Cardiomyocytes

Objective: Myocardial ischemia reperfusion (I/R) damage is a life-threatening vascular emergency after myocardial infarction. Here, we observed the cardioprotective effect of long non-coding RNA (lncRNA) PVT1 knockdown against myocardial I/R damage.

Methods: This study constructed a myocardial I/R-induced mouse model and a hypoxia/reoxygenation (H/R)-treated H9C2 cells. PVT1 expression was examined via RT-qPCR. After silencing PVT1 via shRNA against PVT1, H&E, and Masson staining was performed to observe myocardial I/R damage. Indicators of myocardial injury including cTnI, LDH, BNP, and CK-MB were examined by ELISA. Inflammatory factors (TNF-α, IL-1β, and IL-6), Gasdermin D (GSDMD), and Caspase1 were detected via RT-qPCR, western blot, immunohistochemistry, or immunofluorescence. Furthermore, CCK-8 and flow cytometry were presented for detecting cell viability and apoptosis.

Results: LncRNA PVT1 was markedly up-regulated in myocardial I/R tissue specimens as well as H/R-induced H9C2 cells. Silencing PVT1 significantly lowered serum levels of cTnI, LDH, BNP, and CK-MB in myocardial I/R mice. H&E and Masson staining showed that silencing PVT1 alleviated myocardial I/R injury. PVT1 knockdown significantly lowered the production and release of inflammatory factors as well as inhibited the expression of GSDMD-N and Caspase1 in myocardial I/R tissue specimens as well as H/R-induced H9C2 cells. Moreover, silencing PVT1 facilitated cell viability and induced apoptosis of H/R-treated H9C2 cells.

Conclusion: Our findings demonstrated that silencing PVT1 could alleviate myocardial I/R damage through suppressing GSDMD-mediated pyroptosis in vivo and in vitro. Thus, PVT1 knockdown may offer an alternative therapeutic strategy against myocardial I/R damage.

Pharmacological postconditioning with sappanone A ameliorates myocardial ischemia reperfusion injury and mitochondrial dysfunction via AMPK-mediated mitochondrial quality control

Pharmacological postconditioning (PPC), drug intervention before or during the early minutes of reperfusion, could stimulate cardioprotection as ischemic postconditioning. In this study, we examined whether PPC with sappanone A (SA), a homoisoflavanone with potent antioxidant and anti-inflammatory activity, has a protective effect on myocardial ischemia reperfusion injury (MIRI), and explored the underlying mechanism. A MIRI model was established using the Langendorff method. After 30 min of ischemia, isolated rat hearts were treated with SA at the onset of reperfusion to stimulate PPC. The changes in myocardial infarct size, mitochondrial function, mitochondrial biogenesis, mitophagy, and mitochondrial fission and fusion were detected. The results showed that SA postconditioning decreased the myocardial infarct size, inhibited the release of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), and cardiac troponin (cTnI), as well as improved cardiac function, enhanced myocardial ATP content and mitochondrial complex activity, and prevented the loss of mitochondrial membrane potential and opening of mitochondrial permeability transition pore (mPTP). Mechanistically, we found that SA was an AMP-activated protein kinase (AMPK) activator, and SA postconditioning could facilitate mitochondrial biogenesis by increasing mitochondrial DNA (mtDNA) copy number and the expression of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α). In addition, it balanced mitochondrial dynamics by decreasing fission and increasing fusion, and enhanced mitophagy in an AMPK-dependent manner. Moreover, AMPK silencing abolished the cardioprotection of SA postconditioning. Collectively, our study demonstrated that SA postconditioning ameliorated MIRI and mitochondrial dysfunction by regulation of mitochondrial quality control via activating AMPK. This finding provides a new insight into pharmacological action and clinical use of SA.

miRNA-146a Mimic Inhibits NOX4/P38 Signalling to Ameliorate Mouse Myocardial Ischaemia Reperfusion (I/R) Injury

Evidence suggests that miR-146a is implicated in the pathogenesis of cardiovascular diseases; however, the role of miR-146a in myocardial ischaemia reperfusion (I/R) injury is unclear. The aim of this study was to explore the functional role of miR-146a in myocardial ischaemia reperfusion injury and the underlying mechanism. C57BL/6J mice were subjected to 45 min of ischaemia and 1 week of reperfusion to establish a myocardial I/R injury model. A miR-146a mimic (0.5 mg/kg) was administered intravenously at the beginning of the ischaemia process. Neonatal rat cardiomyocytes were also subjected to hypoxia/reperfusion (H/R). Cells were treated with the miR-146a mimic or antagonist. As a result, the miR-146a mimic attenuated H/R-induced cardiomyocyte injury, as evidenced by increased cell viability and reduced lactate dehydrogenase (LDH) levels. In addition, the miR-146a mimic inhibited oxidative stress in cells suffering from H/R injury. Moreover, the miR-146a antagonist exerted adverse effects in vitro. In mice with myocardial I/R injury, the miR-146a mimic preserved cardiac function and reduced the infarction area and fibrosis. Moreover, the miR-146a mimic decreased the inflammatory response and reactive oxygen species (ROS) accumulation in mouse hearts. Mechanistically, we found that miR-146a directly regulated the transcription of NOX4, which subsequently affected P38 signalling in cardiomyocytes. When we knocked down NOX4, the effects of the miR-146a antagonist in worsening the cell condition were counteracted in in vitro experiments. Taken together, the results suggest that miR-146a protects against myocardial ischaemia reperfusion injury by inhibiting NOX4 signalling. The miR-146a mimic may become a potential therapeutic approach for patients with myocardial ischaemia reperfusion.