CITED4 gene therapy protects against maladaptive cardiac remodeling after ischemia/reperfusion injury in mice.

Cardiac signaling pathways functionally important in the heart's response to exercise often protect the heart against pathological stress, potentially providing novel therapeutic targets. However, it is important to determine which of these pathways can be feasibly targeted in vivo. Transgenic overexpression of exercise-induced CITED4 has been shown to protect against adverse remodeling after ischemia/reperfusion injury (IRI). Here we investigated whether somatic gene transfer of CITED4 in a clinically relevant time frame could promote recovery after IRI. Cardiac CITED4 gene delivery via intravenous AAV9 injections in wild type mice led to an approximately 3-fold increase in cardiac CITED4 expression. After 4 weeks, CITED4-treated animals developed physiological cardiac hypertrophy without adverse remodeling. In IRI, delivery of AAV9-CITED4 after reperfusion resulted in a 6-fold increase in CITED4 expression 1 week after surgery, as well as decreased apoptosis, fibrosis, and inflammatory markers, culminating in a smaller scar and improved cardiac function 8 weeks after IRI, compared with control mice receiving AAV9-GFP. Somatic gene transfer of CITED4 induced a phenotype suggestive of physiological cardiac growth and mitigated adverse remodeling after ischemic injury. These studies support the feasibility of CITED4 gene therapy delivered in a clinically relevant time frame to mitigate adverse ventricular remodeling after ischemic injury.

Up-regulated novel-miR-17 promotes hypothermic reperfusion arrhythmias by negatively targeting Gja1 and mediating activation of the PKC/c-Jun signaling pathway.

BACKGROUND: Hypothermic ischemia-reperfusion arrhythmia is a common complication of cardiothoracic surgery under cardiopulmonary bypass, but few studies have focused on this type of arrhythmia. Our prior study discovered reduced myocardial Cx43 protein levels may be linked to hypothermic reperfusion arrhythmias. However, more detailed molecular mechanism research is required. METHOD: The microRNA and mRNA expression levels in myocardial tissues were detected by real-time quantitative PCR (RT-qPCR). Besides, the occurrence of hypothermic reperfusion arrhythmias and changes in myocardial electrical conduction were assessed by electrocardiography and ventricular epicardial activation mapping. Furthermore, bioinformatics analysis, applying antagonists of miRNA, western blotting, immunohistochemistry, a dual luciferase assay, and pearson correlation analysis were performed to investigate the underlying molecular mechanisms. RESULTS: The expression level of novel-miR-17 was up-regulated in hypothermic ischemia-reperfusion myocardial tissues. Inhibition of novel-miR-17 upregulation ameliorated cardiomyocyte edema, reduced apoptosis, increased myocardial electrical conduction velocity, and shortened the duration of reperfusion arrhythmias. Mechanistic studies showed that novel-miR-17 reduced the expression of Cx43 by directly targeting Gja1 while mediating the activation of the PKC/c-Jun signaling pathway. CONCLUSION: Up-regulated novel-miR-17 is a newly discovered pro-arrhythmic microRNA that may serve as a potential therapeutic target and biomarker for hypothermic reperfusion arrhythmias.

Endoplasmic reticulum stress signaling modulates ischemia/reperfusion injury in the aged heart by regulating mitochondrial maintenance.

Aging is associated with an increased risk of myocardial ischemia/reperfusion injury (IRI). With an increasing prevalence of cardiovascular diseases such as coronary arteriosclerosis in older people, there has been increasing interest in understanding the mechanisms of myocardial IRI to develop therapeutics that can attenuate its damaging effects. Previous studies identified that abnormal mitochondria, involved in cellar senescence and oxidative stress, are the master subcellular organelle that induces IRI. In addition, endoplasmic reticulum (ER) stress is also associated with IRI. Cellular adaptation to ER stress is achieved by the activation of ER molecular chaperones and folding enzymes, which provide an important link between ER stress and oxidative stress gene programs. In this review, we outline how these ER stress-related molecules affect myocardial IRI via the crosstalk of ER stress and mitochondrial homeostasis and discuss how these may offer promising novel therapeutic targets and strategies against age-related cardiovascular diseases.

L-theanine alleviates myocardial ischemia/reperfusion injury by suppressing oxidative stress and apoptosis through activation of the JAK2/STAT3 pathway in mice.

BACKGROUND: L-theanine is a unique non-protein amino acid in tea that is widely used as a safe food additive. We investigated the cardioprotective effects and mechanisms of L-theanine in myocardial ischemia-reperfusion injury (MIRI). METHODS: The cardioprotective effects and mechanisms of L-theanine and the role of Janus Kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling were investigated in MIRI mice using measures of cardiac function, oxidative stress, and apoptosis. RESULTS: Administration of L-theanine (10 mg/kg, once daily) suppressed the MIRI-induced increase in infarct size and serum creatine kinase and lactate dehydrogenase levels, as well as MIRI-induced cardiac apoptosis, as evidenced by an increase in Bcl-2 expression and a decrease in Bax/caspase-3 expression. Administration of L-theanine also decreased the levels of parameters reflecting oxidative stress, such as dihydroethidium, malondialdehyde, and nitric oxide, and increased the levels of parameters reflecting anti-oxidation, such as total antioxidant capacity (T-AOC), glutathione (GSH), and superoxide dismutase (SOD) in ischemic heart tissue. Further analysis showed that L-theanine administration suppressed the MIRI-induced decrease of phospho-JAK2 and phospho-STAT3 in ischemic heart tissue. Inhibition of JAK2 by AG490 (5 mg/kg, once daily) abolished the cardioprotective effect of L-theanine, suggesting that the JAK2/STAT3 signaling pathway may play an essential role in mediating the anti-I/R effect of L-theanine. CONCLUSIONS: L-theanine administration suppresses cellular apoptosis and oxidative stress in part via the JAK2/STAT3 signaling pathway, thereby attenuating MIRI-induced cardiac injury. L-theanine could be developed as a potential drug to alleviate cardiac damage in MIRI.

L-carnitine decreases myocardial injury in children undergoing open-heart surgery: A randomized controlled trial.

Myocardial injury in open-heart surgery is related to several factors including ischemia-reperfusion injury, generation of reactive oxygen species, increased production of inflammatory mediators, and enhancement of apoptosis of cardiomyocytes. The aim of this study was to study the effect of L-carnitine on myocardial injury in children undergoing open-heart surgery. This clinical trial was performed on 60 children with congenital heart disease (CHD) who underwent open-heart surgery. They were randomized into two groups: L-carnitine group who received L-carnitine 50 mg\kg\day once daily for 1 month before cardiac surgery and control group who received placebo for 1 month before cardiac surgery. Left ventricular cardiac function was assessed by conventional echocardiography to measure left ventricular ejection fraction (LVEF) and two-dimensional speckle tracking echocardiography (2D-STE) to determine left ventricular global longitudinal strain (2D-LV GLS). Blood samples were obtained pre-operatively at baseline before the administration of L-carnitine or placebo and 12 h post-operatively to measure the level of malondialdehyde (MDA), superoxide dismutase (SOD), fas, caspase-3, creatinine kinase-MB (CK-MB), and troponin I. L-carnitine group had significantly lower post-operative level of oxidative stress marker (MDA), apoptosis markers (fas and caspase-3), and myocardial injury markers (CK-MB and troponin I), but they had significantly higher SOD post-operative level compared to the control group. In addition, post-operative LVEF and 2D-LVGLS were significantly lower in the control group compared to L-carnitine group.   Conclusion: L-carnitine can reduce myocardial injury, improve post-operative left ventricular cardiac function, and may provide myocardium protection in children with CHD who underwent open-heart surgery.   Trial registration: The clinical trial was registered at www.pactr.org with registration number PACTR202010570607420 at 29/10/2020 before recruiting the patients. What is Known: • Myocardial injury in open-heart surgery is related to several factors including ischemia-reperfusion injury, generation of reactive oxygen species, increased production of inflammatory mediators, and enhancement of apoptosis of cardiomyocytes. • L-carnitine was reported to have myocardial protective effects in rheumatic valvular surgery and coronary artery bypass graft (CABG) in adults; however, there is no evidence on its effectiveness in children undergoing open-heart surgery. What is New: • L-carnitine significantly lowered the post-operative level of oxidative stress marker (MDA), apoptosis markers (fas and caspase-3), and myocardial injury markers (CK-MB and troponin I) in the treatment group. • L-carnitine can reduce myocardial injury, improve post-operative left ventricular cardiac function, and may provide myocardium protection in children with CHD who underwent open-heart surgery.

Development of a novel 3D perfusable vascular graft model to elucidate the mechanisms for congenital heart disorders.

Pediatric heart transplantation is hampered by a chronic shortage of donor organs. This problem is further confounded by graft rejection. Identification of earlier indicators of pediatric graft rejection and development of subsequent strategies to counteract these effects will increase the longevity of transplanted pediatric hearts. Heart transplant reject is due to a complex series of events, resulting in CAV, which is thought to be mediated through a host immune response. However, the earlier events leading to CAV are not very well known. We hypothesize that early events related to ischemia reperfusion injury during pediatric heart transplantation are responsible for CAV and subsequent graft rejection. Identification of the molecular markers of ischemia reperfusion injury and development of subsequent therapies to block these pathways can potentially lead to a therapeutic strategy to reduce CAV and increase the longevity of the transplanted heart. To accomplish this goal, we have developed a perfusable vascular graft model populated with endothelial cells and demonstrated the feasibility of this model to understand the early events of ischemia reperfusion injury.

Ischemia promotes acyl-CoAs dephosphorylation and propionyl-CoA accumulation.

INTRODUCTION: Our untargeted metabolic data unveiled that Acyl-CoAs undergo dephosphorylation, however little is known about these novel metabolites and their physiology/pathology relevance. OBJECTIVES: To understand the relationship between acyl-CoAs dephosphorylation and energy status as implied in our previous work, we seek to investigate how ischemia (energy depletion) triggers metabolic changes, specifically acyl-CoAs dephosphorylation in this work. METHODS: Rat hearts were isolated and perfused in Langendorff mode for 15 min followed by 0, 5, 15, and 30 minutes of global ischemia. The heart tissues were harvested for metabolic analysis. RESULTS: As expected, ATP and phosphocreatine were significantly decreased during ischemia. Most short- and medium-chain acyl-CoAs progressively increased with ischemic time from 0 to 15 min, whereas a 30-minute ischemia did not lead to further change. Unlike other acyl-CoAs, propionyl-CoA accumulated progressively in the hearts that underwent ischemia from 0 to 30 min. Progressive dephosphorylation occurred to all assayed acyl-CoAs and free CoA regardless their level changes during the ischemia. CONCLUSION: The present work further confirms that dephosphorylation of acyl-CoAs is an energy-dependent process and how this dephosphorylation is mediated warrants further investigations. It is plausible that dephosphorylation of acyl-CoAs and limited anaplerosis are involved in ischemic injuries to heart. Further investigations are warranted to examine the mechanisms of acyl-CoA dephosphorylation and how the dephosphorylation is possibly involved in ischemic injuries.

Cardiovascular aspects of the (pro)renin receptor: Function and significance.

Cardiovascular diseases (CVDs), including all types of disorders related to the heart or blood vessels, are the major public health problems and the leading causes of mortality globally. (Pro)renin receptor (PRR), a single transmembrane protein, is present in cardiomyocytes, vascular smooth muscle cells, and endothelial cells. PRR plays an essential role in cardiovascular homeostasis by regulating the renin-angiotensin system and several intracellular signals such as mitogen-activated protein kinase signaling and wnt/ß-catenin signaling in various cardiovascular cells. This review discusses the current evidence for the pathophysiological roles of the cardiac and vascular PRR. Activation of PRR in cardiomyocytes may contribute to myocardial ischemia/reperfusion injury, cardiac hypertrophy, diabetic or alcoholic cardiomyopathy, salt-induced heart damage, and heart failure. Activation of PRR promotes vascular smooth muscle cell proliferation, endothelial cell dysfunction, neovascularization, and the progress of vascular diseases. In addition, phenotypes of animals transgenic for PRR and the hypertensive actions of PRR in the brain and kidney and the soluble PRR are also discussed. Targeting PRR in local tissues may offer benefits for patients with CVDs, including heart injury, atherosclerosis, and hypertension.

Magnetic vagus nerve stimulation alleviates myocardial ischemia-reperfusion injury by the inhibition of pyroptosis through the M2AChR/OGDHL/ROS axis in rats.

BACKGROUND: Myocardial ischemia-reperfusion (I/R) injury is accompanied by an imbalance in the cardiac autonomic nervous system, characterized by over-activated sympathetic tone and reduced vagal nerve activity. In our preceding study, we pioneered the development of the magnetic vagus nerve stimulation (mVNS) system. This system showcased precise vagus nerve stimulation, demonstrating remarkable effectiveness and safety in treating myocardial infarction. However, it remains uncertain whether mVNS can mitigate myocardial I/R injury and its specific underlying mechanisms. In this study, we utilized a rat model of myocardial I/R injury to delve into the therapeutic potential of mVNS against this type of injury. RESULTS: Our findings revealed that mVNS treatment led to a reduction in myocardial infarct size, a decrease in ventricular fibrillation (VF) incidence and a curbing of inflammatory cytokine release. Mechanistically, mVNS demonstrated beneficial effects on myocardial I/R injury by inhibiting NLRP3-mediated pyroptosis through the M2AChR/OGDHL/ROS axis. CONCLUSIONS: Collectively, these outcomes highlight the promising potential of mVNS as a treatment strategy for myocardial I/R injury.

Long Noncoding RNA Cardiac Physiological Hypertrophy-Associated Regulator Induces Cardiac Physiological Hypertrophy and Promotes Functional Recovery After Myocardial Ischemia-Reperfusion Injury.

BACKGROUND: The benefits of exercise training in the cardiovascular system have been well accepted; however, the underlying mechanism remains to be explored. Here, we report the initial functional characterization of an exercise-induced cardiac physiological hypertrophy-associated novel long noncoding RNA (lncRNA). METHODS: Using lncRNA microarray profiling, we identified lncRNAs in contributing the modulation of exercise-induced cardiac growth that we termed cardiac physiological hypertrophy-associated regulator (CPhar). Mice with adeno-associated virus serotype 9 driving CPhar overexpression and knockdown were used in in vivo experiments. Swim training was used to induce physiological cardiac hypertrophy in mice, and ischemia reperfusion injury surgery was conducted to investigate the protective effects of CPhar in mice. To investigate the mechanisms of CPhar's function, we performed various analyses including quantitative reverse transcription polymerase chain reaction, Western blot, histology, cardiac function (by echocardiography), functional rescue experiments, mass spectrometry, in vitro RNA transcription, RNA pulldown, RNA immunoprecipitation, chromatin immunoprecipitation assay, luciferase reporter assay, and coimmunoprecipitation assays. RESULTS: We screened the lncRNAs in contributing the modulation of exercise-induced cardiac growth through lncRNA microarray profiling and found that CPhar was increased with exercise and was necessary for exercise-induced physiological cardiac growth. The gain and loss of function of CPhar regulated the expression of proliferation markers, hypertrophy, and apoptosis in cultured neonatal mouse cardiomyocytes. Overexpression of CPhar prevented myocardial ischemia reperfusion injury and cardiac dysfunction in vivo. We identified DDX17 (DEAD-Box Helicase 17) as a binding partner of CPhar in regulating CPhar downstream factor ATF7 (activating transcription factor 7) by sequestering C/EBPß (CCAAT/enhancer binding protein beta). CONCLUSIONS: Our study of this lncRNA CPhar provides new insights into the regulation of exercise-induced cardiac physiological growth, demonstrating the cardioprotective role of CPhar in the heart, and expanding our mechanistic understanding of lncRNA function, as well.

Treatment of myocardial ischaemia-reperfusion injury in patients with ST-segment elevation myocardial infarction: promise, disappointment, and hope.

Acute myocardial infarction (AMI) is a major cause of morbidity and mortality worldwide. Timely reperfusion with primary percutaneous coronary intervention (PPCI) remains the gold standard in patients presenting with ST-segment elevation myocardial infarction (STEMI), limiting infarct size, preserving left ventricular ejection fraction (LVEF), and improving clinical outcomes. Despite this, a significant proportion of STEMI patients develop post-infarct heart failure. We review the current understanding and up-to-date evidence base for therapeutic intervention of ischaemia-reperfusion injury (IRI), a combination of myocardial ischaemia secondary to acute coronary occlusion and reperfusion injury leading to further myocardial injury and cell death. Multiple treatment modalities have been shown to be cardioprotective and reduce IRI in experimental animal models. Recent phase II/III randomised controlled trials (RCT) have assessed multiple cardioprotective strategies ranging from ischaemic conditioning, therapeutic hypothermia and hyperoxaemia to pharmacological therapies. While several therapies have been shown to reduce infarct size in animal models or proof-of-concept studies, many larger scale trial results have proven inconsistent and disappointing. Hard clinical outcomes remain elusive. We discuss potential reasons for the difficulties in translation to clinical practice.

Effect of soya phosphatidylcholine and possible underlying mechanism on ischemia/reperfusion injury in isolated perfused rat heart: an experimental and computational study.

This study was designed to assess the effect of soya phosphatidylcholine (SPC) against ischemia/reperfusion (I/R) injury and the possible underlying mechanism using experimental and computational studies. I/R injury was induced by global ischemia for 30 min followed by reperfusion for 120 min. The perfusion of the SPC was performed for 10 min before inducing global ischemia. In the mechanistic study, the involvement of specific cellular pathways was identified using various inhibitors such as ATP-dependent potassium channel (KATP) inhibitor (glibenclamide), protein kinase C (PKC) inhibitor (chelerythrine), non-selective nitric oxide synthase inhibitor (L-NAME), and endothelium remover (Triton X-100). The computational study of various ligands was performed on toll-like receptor 4 (TLR4) protein using AutoDock version 4.0. SPC (100 µM) significantly decreased the levels of cardiac damage markers and %infarction compared with the vehicle control (VC). Furthermore, cardiodynamics (indices of left ventricular contraction (dp/dtmax), indices of left ventricular relaxation (dp/dtmin), coronary flow, and antioxidant enzyme levels were significantly improved as compared with VC. This protective effect was attenuated by glibenclamide, chelerythrine, and Triton X-100, but it was not attenuated by L-NAME. The computational study showed a significant bonding affinity of SPC to the TLR4-MD2 complex. Thus, SPC reduced myocardial I/R injury in isolated perfused rat hearts, which might be governed by the KATP channel, PKC, endothelium response, and TLR4-MyD88 signaling pathway.

Midazolam suppresses ischemia/reperfusion-induced cardiomyocyte apoptosis by inhibiting the JNK/p38 MAPK signaling pathway.

Myocardial ischemia/reperfusion (I/R) injury causes irreversible injury to the heart, thereby causing acute myocardial infarction. Midazolam is a benzodiazepine commonly utilized in anesthesia and intensive care. Research has indicated that midazolam plays a critical role in many diseases; however, the function of midazolam in myocardial injury induced by I/R still needs further investigation. The infarct size and damage to the heart tissues were examined through 2,3,5-triphenyl tetrazolium chloride (TTC) staining and hematoxylin and eosin staining. The creatine kinase-myocardial band isoenzyme, lactate dehydrogenase, and aspartate aminotransferase levels were tested using commercial kits. Cell apoptosis was determined through TUNEL staining or flow cytometry assays. Bax, Bcl-2, cleaved caspase-3, phospho-38 (p-p38), p38, p-JNK, JNK, extracellular signal-regulated kinases (ERK), and p-ERK expression was examined through Western blot. In our study, midazolam was shown to suppress the infarct size and heart tissue damage and reduce myocardial enzyme leakage in I/R rats. Additionally, midazolam was found to retard cardiomyocyte apoptosis in I/R rats. The JNK/p38 MAPK signaling pathway in I/R rats was inhibited by midazolam. Our findings demonstrated that in hypoxia/reoxygenation (H/R) - mediated H9C2 cells, anisomycin abolished the suppressive effects of midazolam on the JNK/p38 MAPK signaling pathway. Next, exploration discovered that anisomycin abolished the cytoprotective effects of midazolam on H/R-treated H9C2 cell apoptosis. In conclusion, this work demonstrated that midazolam retarded I/R-induced cardiomyocyte apoptosis by inhibiting the JNK/p38 MAPK signaling pathway. These results may provide new insight into the treatment of myocardial I/R injury.

Reactive Oxygen Species Cause Exercise-Induced Angina in a Myocardial Ischaemia-Reperfusion Injury Model.

Percutaneous coronary intervention (PCI) effectively treats obstructive coronary artery syndrome. However, 30-40% patients continue to have angina after a successful PCI, thereby reducing patient satisfaction. The mechanisms underlying persistent angina after revascularisation therapy are still poorly understood; hence, the treatment or guideline for post-PCI angina remains unestablished. Thus, this study aimed to investigate the mechanisms underlying effort angina in animals following myocardial ischaemia-reperfusion (I/R) injury. Phosphorylated extracellular signal-regulated kinase (p-ERK), a marker for painful stimulation-induced neuronal activation, was used for the investigation. After a forced treadmill exercise (FTE), the number of p-ERK-expressing neurons increased in the superficial dorsal horn of the I/R model animals. Moreover, FTE evoked hydrogen peroxide (H2O2) production in the I/R-injured heart, inducing angina through TRPA1 activation on cardiac sensory fibres. Notably, the treatment of a TEMPOL, a reactive oxygen species scavenger, or TRPA1-/- mice successfully alleviated the FTE-induced p-ERK expression in the dorsal horn. The production of H2O2, a reactive oxygen species, through physical exercise contributes to angina development following I/R. Hence, our findings may be useful for understanding and treating angina following revascularisation therapy.

Protective Effect of CXCR4 Antagonist DBPR807 against Ischemia-Reperfusion Injury in a Rat and Porcine Model of Myocardial Infarction: Potential Adjunctive Therapy for Percutaneous Coronary Intervention.

CXCR4 antagonists have been claimed to reduce mortality after myocardial infarction in myocardial infarction (MI) animals, presumably due to suppressing inflammatory responses caused by myocardial ischemia-reperfusion injury, thus, subsequently facilitating tissue repair and cardiac function recovery. This study aims to determine whether a newly designed CXCR4 antagonist DBPR807 could exert better vascular-protective effects than other clinical counterparts (e.g., AMD3100) to alleviate cardiac damage further exacerbated by reperfusion. Consequently, we find that instead of traditional continuous treatment or multiple-dose treatment at different intervals of time, a single-dose treatment of DBPR807 before reperfusion in MI animals could attenuate inflammation via protecting oxidative stress damage and preserve vascular/capillary density and integrity via mobilizing endothelial progenitor cells, leading to a desirable fibrosis reduction and recovery of cardiac function, as evaluated with the LVEF (left ventricular ejection fraction) in infarcted hearts in rats and mini-pigs, respectively. Thus, it is highly suggested that CXCR4 antagonists should be given at a single high dose prior to reperfusion to provide the maximal cardiac functional improvement. Based on its favorable efficacy and safety profiles indicated in tested animals, DBPR807 has a great potential to serve as an adjunctive medicine for percutaneous coronary intervention (PCI) therapies in acute MI patients.

Downregulation of the zinc transporter SLC39A13 (ZIP13) is responsible for the activation of CaMKII at reperfusion and leads to myocardial ischemia/reperfusion injury in mouse hearts.

While Zn2+ dyshomeostasis is known to contribute to ischemia/reperfusion (I/R) injury, the roles of zinc transporters that are responsible for Zn2+ homeostasis in the pathogenesis of I/R injury remain to be addressed. This study reports that ZIP13 (SLC39A13), a zinc transporter, plays a role in myocardial I/R injury by modulating the Ca2+ signaling pathway rather than by regulating Zn2+ transport. ZIP13 is downregulated upon reperfusion in mouse hearts or in H9c2 cells at reoxygenation. Ca2+ but not Zn2+ was responsible for ZIP13 downregulation, implying that ZIP13 may play a role in I/R injury through the Ca2+ signaling pathway. In line with our assumption, knockout of ZIP13 resulted in phosphorylation (Thr287) of Ca2+-calmodulin-dependent protein kinase (CaMKII), indicating that downregulation of ZIP13 leads to CaMKII activation. Further studies showed that the heart-specific knockout of ZIP13 enhanced I/R-induced CaMKII phosphorylation in mouse hearts. In contrast, overexpression of ZIP13 suppressed I/R-induced CaMKII phosphorylation. Moreover, the heart-specific knockout of ZIP13 exacerbated myocardial infarction in mouse hearts subjected to I/R, whereas overexpression of ZIP13 reduced infarct size. In addition, knockout of ZIP13 induced increases of mitochondrial Ca2+, ROS, mitochondrial swelling, decrease in the mitochondrial respiration control rate (RCR), and dissipation of mitochondrial membrane potential (ΔΨm) in a CaMKII-dependent manner. These data suggest that downregulation of ZIP13 at reperfusion contributes to myocardial I/R injury through activation of CaMKII and the mitochondrial death pathway.

Interleukin-7 aggravates myocardial ischaemia/reperfusion injury by regulating macrophage infiltration and polarization.

Interleukin (IL)-7 is known to enhance the macrophages cytotoxic activity and that macrophages play a pivotal role in the development and progression of myocardial ischaemia/reperfusion (I/R) injury. However, the effects of IL-7 on macrophages infiltration and polarization in myocardial I/R injury are currently unclear. This study aimed to evaluate the effects of the IL-7 expression on myocardial I/R injury and their relationship with macrophages. The data showed that IL-7 expression in mouse heart tissue increases following I/R injury and that IL-7 knockout or anti-IL-7 antibody treatment significantly improve I/R injury, including reduction in myocardial infarction area, a serum troponin T level decreases and an improvement in cardiac function. On the other hand, recombinant IL-7 (rIL-7) supplementation induces opposite effects and the anti-IL-7 antibody significantly reduces the cardiomyocyte apoptosis and macrophage infiltration. rIL-7 cannot directly cause apoptosis, but it can induce cardiomyocyte apoptosis through macrophages, in addition to increase the macrophages migration in vitro. Anti-IL-7 antibody affects the cytokine production in T helper (Th) 1 and Th2 cells and also promotes the macrophages differentiation to M2 macrophages. However, anti-IL-7 antibody does not reduce the M1 macrophage number, and it only increases the ratio of M2/M1 macrophages in mice heart tissues after I/R injury. Taking together, these data reveal that IL-7 plays an intensifying role in myocardial I/R injury by promoting cardiomyocyte apoptosis through the regulation of macrophage infiltration and polarization.

Exosomes derived from MSC pre-treated with oridonin alleviates myocardial IR injury by suppressing apoptosis via regulating autophagy activation.

This study aimed to investigate the molecular mechanisms underlying the role of bone marrow mesenchymal stem cells (BMMSCs)-derived exosomes in ischaemia/reperfusion (IR)-induced damage, and the role of oridonin in the treatment of IR. Exosomes were isolated from BMMSCs. Western blot analysis was done to examine the expression of proteins including CD63, CD8, apoptotic-linked gene product 2 interacting protein X (AliX), Beclin-1, ATG13, B-cell lymphoma-2 (Bcl-2), apoptotic peptidase activating factor 1 (Apaf1) and Bcl2-associated X (Bax) in different treatment groups. Accordingly, the expression of CD63, CD81 and AliX was higher in BMMSCs-EXOs and IR + BMMSCs-EXOs + ORI groups compared with that in the BMMSCs group. And BMMSCs-derived exosomes inhibited the progression of IR-induced myocardial damage, while this protective effect was boosted by the pre-treatment with oridonin. Moreover, Beclin-1, ATG13 and Bcl-2 were significantly down-regulated while Apaf1 and Bax were significantly up-regulated in IR rats. And the presence of BMMSCs-derived exosomes partly alleviated IR-induced dysregulation of these proteins, while the oridonin pre-treatment boosted the effect of these BMMSCs-derived exosomes. The inhibited proliferation and promoted apoptosis of H9c2 cells induced by hypoxia/reperfusion (HR) were mitigated by the administration of BMMSCs-derived exosomes. Meanwhile, HR also induced down-regulation of Beclin-1, ATG13 and Bcl-2 expression and up-regulation of Apaf1 and Bax, which were mitigated by the administration of BMMSCs-derived exosomes. And oridonin pre-treatment boosted the effect of BMMSCs-derived exosomes. In conclusion, our results validated that BMMSCs-derived exosomes suppressed the IR-induced damages by participating in the autophagy process, while the pre-treatment with oridonin could boost the protective effect of BMMSCs-derived exosomes.

Nesfatin-1 inhibits myocardial ischaemia/reperfusion injury through activating Akt/ERK pathway-dependent attenuation of endoplasmic reticulum stress.

Nesfatin-1 (encoded by NUCB2) is a cardiac peptide possessing protective activities against myocardial ischaemia/reperfusion (MI/R) injury. However, the regulation of NUCB2/nesfatin-1 and the molecular mechanisms underlying its roles in MI/R injury are not clear. Here, by investigating a mouse MI/R injury model developed with transient myocardial ischaemia followed by reperfusion, we found that the levels of NUCB2 transcript and nesfatin-1 amount in the heart were both decreased, suggesting a transcriptional repression of NUCB2/nesfatin-1 in response to MI/R injury. Moreover, cardiac nesfatin-1 restoration reduced infarct size, troponin T (cTnT) level and myocardial apoptosis, supporting its cardioprotection against MI/R injury in vivo. Mechanistically, the Akt/ERK pathway was activated, and in contrast, endoplasmic reticulum (ER) stress was attenuated by nesfatin-1 following MI/R injury. In an in vitro system, similar results were obtained in nesfatin-1-treated H9c2 cardiomyocytes with hypoxia/reoxygenation (H/R) injury. More importantly, the treatment of wortmannin, an inhibitor of Akt/ERK pathway, abrogated nesfatin-1 effects on attenuating ER stress and H/R injury in H9c2 cells. Furthermore, nesfatin-1-mediated protection against H/R injury also vanished in the presence of tunicamycin (TM), an ER stress inducer. Lastly, Akt/ERK inhibition reversed nesfatin-1 effects on mouse ER stress and MI/R injury in vivo. Taken together, these findings demonstrate that NUCB2/nesfatin-1 inhibits MI/R injury through attenuating ER stress, which relies on Akt/ERK pathway activation. Hence, our study provides a molecular basis for understanding how NUCB2/nesfatin-1 reduces MI/R injury.

Downregulation of p300/CBP-associated factor inhibits cardiomyocyte apoptosis via suppression of NF-κB pathway in ischaemia/reperfusion injury rats.

Cardiomyocyte apoptosis is the main reason of cardiac injury after myocardial ischaemia-reperfusion (I/R) injury (MIRI), but the role of p300/CBP-associated factor (PCAF) on myocardial apoptosis in MIRI is unknown. The aim of this study was to investigate the main mechanism of PCAF modulating cardiomyocyte apoptosis in MIRI. The MIRI model was constructed by ligation of the rat left anterior descending coronary vessel for 30 min and reperfusion for 24 h in vivo. H9c2 cells were harvested after induced by hypoxia for 6 h and then reoxygenation for 24 h (H/R) in vitro. The RNA interference PCAF expression adenovirus was transfected into rat myocardium and H9c2 cells. The area of myocardial infarction, cardiac function, myocardial injury marker levels, apoptosis, inflammation and oxidative stress were detected respectively. Both I/R and H/R remarkably upregulated the expression of PCAF, and downregulation of PCAF significantly attenuated myocardial apoptosis, inflammation and oxidative stress caused by I/R and H/R. In addition, downregulation of PCAF inhibited the activation of NF-κB signalling pathway in cardiomyocytes undergoing H/R. Pretreatment of lipopolysaccharide, a NF-κB pathway activator, could blunt these protective effects of PCAF downregulation on myocardial apoptosis in MIRI. These results highlight that downregulation of PCAF could reduce cardiomyocyte apoptosis by inhibiting the NF-κB pathway, thereby providing protection for MIRI. Therefore, PCAF might be a promising target for protecting against cardiac dysfunction induced by MIRI.