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Acute myocardial infarction (AMI) is the leading cause of cardiovascular death and remains the most common cause of heart failure. Reopening of the occluded artery, i.e., reperfusion, is the only way to save the myocardium. However, the expected benefits of reducing infarct size are disappointing due to the reperfusion paradox, which also induces specific cell death. These ischemia-reperfusion (I/R) lesions can account for up to 50% of final infarct size, a major determinant for both mortality and the risk of heart failure (morbidity). In this review, we provide a detailed description of the cell death and inflammation mechanisms as features of I/R injury and cardioprotective strategies such as ischemic postconditioning as well as their underlying mechanisms. Due to their biological properties, the use of mesenchymal stromal/stem cells (MSCs) has been considered a potential therapeutic approach in AMI. Despite promising results and evidence of safety in preclinical studies using MSCs, the effects reported in clinical trials are not conclusive and even inconsistent. These discrepancies were attributed to many parameters such as donor age, in vitro culture, and storage time as well as injection time window after AMI, which alter MSC therapeutic properties. In the context of AMI, future directions will be to generate MSCs with enhanced properties to limit cell death in myocardial tissue and thereby reduce infarct size and improve the healing phase to increase postinfarct myocardial performance.

L-type voltage-gated calcium channels are involved in multiple physiological functions. Currently available antagonists do not discriminate between L-type channel isoforms. Importantly, no selective blocker is available to dissect the role of L-type isoforms Ca v 1.2 and Ca v 1.3 that are concomitantly co-expressed in the heart, neuroendocrine and neuronal cells. Here we show that calciseptine, a snake toxin purified from mamba venom, selectively blocks Ca v 1.2 -mediated L-type calcium currents (I CaL ) at concentrations leaving Ca v 1.3-mediated I CaL unaffected in both native cardiac myocytes and HEK-293T cells expressing recombinant Ca v 1.2 and Ca v 1.3 channels. Functionally, calciseptine potently inhibits cardiac contraction without altering the pacemaker activity in sino-atrial node cells, underscoring differential roles of Ca v 1.2- and Ca v 1.3 in cardiac contractility and automaticity. In summary, calciseptine is a selective L-type Ca v 1.2 Ca 2+ channel blocker and should be a valuable tool to dissect the role of these L-channel isoforms., (© 2024. The Author(s).)

Background: Acute myocardial infarction (AMI) is the major cause of cardiovascular mortality worldwide. Most ischemic episodes are triggered by an increase in heart rate, which induces an imbalance between myocardial oxygen delivery and consumption. Developing drugs that selectively reduce heart rate by inhibiting ion channels involved in heart rate control could provide more clinical benefits. The Ca v 1.3-mediated L-type Ca 2+ current ( I Cav1.3 ) play important roles in the generation of heart rate. Therefore, they can constitute relevant targets for selective control of heart rate and cardioprotection during AMI., Objective: We aimed to investigate the relationship between heart rate and infarct size using mouse strains knockout for Ca v 1.3 ( Ca v 1.3 -/- ) L-type calcium channel and of the cardiac G protein gated potassium channel ( Girk4 -/- ) in association with the funny (f)-channel inhibitor ivabradine., Methods: Wild-type (WT), Ca v 1.3 +/- , Ca v 1.3 -/- and Girk4 -/- mice were used as models of respectively normal heart rate, moderate heart rate reduction, bradycardia, and mild tachycardia, respectively. Mice underwent a surgical protocol of myocardial IR (40 min ischemia and 60 min reperfusion). Heart rate was recorded by one-lead surface ECG recording, and infarct size measured by triphenyl tetrazolium chloride staining. In addition, Ca v 1.3 -/- and WT hearts perfused on a Langendorff system were subjected to the same ischemia-reperfusion protocol ex vivo , without or with atrial pacing, and the coronary flow was recorded., Results: Ca v 1.3 -/- mice presented reduced infarct size (-29%), while Girk4 -/- displayed increased infarct size (+30%) compared to WT mice. Consistently, heart rate reduction in Ca v 1.3 +/- or by the f-channel blocker ivabradine was associated with significant decrease in infarct size (-27% and -32%, respectively) in comparison to WT mice., Conclusion: Our results show that decreasing heart rate allows to protect the myocardium against IR injury in vivo and reveal a close relationship between basal heart rate and IR injury. In addition, this study suggests that targeting Ca v 1.3 channels could constitute a relevant target for reducing infarct size, since maximal heart rate dependent cardioprotective effect is already observed in Ca v 1.3 +/- mice., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Delgado-Betancourt, Chinda, Mesirca, Barrere, Covinhes, Gallot, Vincent, Bidaud, Kumphune, Nargeot, Piot, Wickman, Mangoni and Barrère-Lemaire.)

Cardiovascular diseases (CVD) including acute myocardial infarction (AMI) rank first in worldwide mortality and according to the World Health Organization (WHO), they will stay at this rank until 2030. Prompt revascularization of the occluded artery to reperfuse the myocardium is the only recommended treatment (by angioplasty or thrombolysis) to decrease infarct size (IS). However, despite beneficial effects on ischemic lesions, reperfusion leads to ischemia-reperfusion (IR) injury related mainly to apoptosis. Improvement of revascularization techniques and patient care has decreased myocardial infarction (MI) mortality however heart failure (HF) morbidity is increasing, contributing to the cost-intense worldwide HF epidemic. Currently, there is no treatment for reperfusion injury despite promising results in animal models. There is now an obvious need to develop new cardioprotective strategies to decrease morbidity/mortality of CVD, which is increasing due to the aging of the population and the rising prevalence rates of diabetes and obesity. In this review, we will summarize the different therapeutic peptides developed or used focused on the treatment of myocardial IR injury (MIRI). Therapeutic peptides will be presented depending on their interacting mechanisms (apoptosis, necroptosis, and inflammation) reported as playing an important role in reperfusion injury following myocardial ischemia. The search and development of therapeutic peptides have become very active, with increasing numbers of candidates entering clinical trials. Their optimization and their potential application in the treatment of patients with AMI will be discussed., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Fernandez Rico, Konate, Josse, Nargeot, Barrère-Lemaire and Boisguérin.)

Myocardial infarction ranks first for the mortality worldwide. Because the adult heart is unable to regenerate, fibrosis develops to compensate for the loss of contractile tissue after infarction, leading to cardiac remodeling and heart failure. Adult mesenchymal stem cells (MSC) regenerative properties, as well as their safety and efficacy, have been demonstrated in preclinical models. However, in clinical trials, their beneficial effects are controversial. In an experimental model of arthritis, we have previously shown that PPARβ / δ deficiency enhanced the therapeutic effect of MSC. The aim of the present study was to compare the therapeutic effects of wild-type MSC (MSC) and MSC deficient for PPARβ / δ (KO MSC) perfused in an ex vivo mouse model of ischemia-reperfusion (IR) injury. For this purpose, hearts from C57BL/6J mice were subjected ex vivo to 30 min ischemia followed by 1-h reperfusion. MSC and KO MSC were injected into the Langendorff system during reperfusion. After 1 h of reperfusion, the TTC method was used to assess infarct size. Coronary effluents collected in basal condition (before ischemia) and after ischemia at 1 h of reperfusion were analyzed for their cytokine profiles. The dose-response curve for the cardioprotection was established ex vivo using different doses of MSC (3.10 5 , 6.10 5 , and 24.10 5 cells / heart) and the dose of 6.10 5 MSC was found to be the optimal concentration. We showed that the cardioprotective effect of MSC was PPARβ / δ-dependent since it was lost using KO MSC. Moreover, cytokine profiling of the coronary effluents collected in the eluates after 60 min of reperfusion revealed that MSC treatment decreases CXCL1 chemokine and interleukin-6 release compared with untreated hearts. This anti-inflammatory effect of MSC was also observed when hearts were treated with PPARβ / δ-deficient MSC. In conclusion, our study revealed that the acute cardioprotective properties of MSC in an ex vivo model of IR injury, assessed by a decreased infarct size at 1 h of reperfusion, are PPARβ / δ-dependent but not related to their anti-inflammatory effects., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Nernpermpisooth, Sarre, Barrere, Contreras, Luz-Crawford, Tejedor, Vincent, Piot, Kumphune, Nargeot, Jorgensen, Barrère-Lemaire and Djouad.)

Myocardial ischemia/reperfusion (I/R) injury is a major cause of mortality and morbidity worldwide. Among factors contributing to I/R injury, proteolytic enzymes could also cause cellular injury, expand the injured area and induce inflammation, which then lead to cardiac dysfunction. Therefore, protease inhibition seems to provide therapeutic benefits. Previous studies showed the cardioprotective effect of secretory leukocyte protease inhibitor (SLPI) against myocardial I/R injury. However, the effect of a post-ischemic treatment with SLPI in an in vivo I/R model has never been investigated. In the present study, recombinant human (rh) SLPI (rhSLPI) was systemically injected during coronary artery occlusion or at the onset of reperfusion. The results show that post-ischemic treatment with rhSLPI could significantly reduce infarct size, Lactate Dehydrogenase (LDH) and Creatine kinase-MB (CK-MB) activity, inflammatory cytokines and protein carbonyl levels, as well as improving cardiac function. The cardioprotective effect of rhSLPI is associated with the attenuation of p38 MAPK phosphorylation, Bax, caspase-3 and -8 protein levels and enhancement of pro-survival kinase Akt and ERK1/2 phosphorylation. In summary, this is the first report showing the cardioprotective effects against myocardial I/R injury of post-ischemic treatments with rhSLPI in vivo. Thus, these results suggest that SLPI could be used as a novel therapeutic strategy to reduce myocardial I/R injury.

Cardiac automaticity is set by pacemaker activity of the sinus node (SAN). In addition to the ubiquitously expressed cardiac voltage-gated L-type Ca v 1.2 Ca 2+ channel isoform, pacemaker cells within the SAN and the atrioventricular node co-express voltage-gated L-type Ca v 1.3 and T-type Ca v 3.1 Ca 2+ channels (SAN-VGCCs). The role of SAN-VGCCs in automaticity is incompletely understood. We used knockout mice carrying individual genetic ablation of Ca v 1.3 (Ca v 1.3 -/- ) or Ca v 3.1 (Ca v 3.1 -/- ) channels and double mutant Ca v 1.3 -/- /Ca v 3.1 -/- mice expressing only Ca v 1.2 channels. We show that concomitant loss of SAN-VGCCs prevents physiological SAN automaticity, blocks impulse conduction and compromises ventricular rhythmicity. Coexpression of SAN-VGCCs is necessary for impulse formation in the central SAN. In mice lacking SAN-VGCCs, residual pacemaker activity is predominantly generated in peripheral nodal and extranodal sites by f-channels and TTX-sensitive Na + channels. In beating SAN cells, ablation of SAN-VGCCs disrupted late diastolic local intracellular Ca 2+ release, which demonstrates an important role for these channels in supporting the sarcoplasmic reticulum based "Ca 2+ clock" mechanism during normal pacemaking. These data implicate an underappreciated role for co-expression of SAN-VGCCs in heart automaticity and define an integral role for these channels in mechanisms that control the heartbeat.

Reperfusion therapy during myocardial infarction (MI) leads to side effects called ischemia-reperfusion (IR) injury for which no treatment exists. While most studies have targeted the intrinsic apoptotic pathway to prevent IR injury with no successful clinical translation, we evidenced recently the potent cardioprotective effect of the anti-apoptotic Tat-DAXXp (TD) peptide targeting the FAS-dependent extrinsic pathway. The aim of the present study was to evaluate TD long term cardioprotective effects against IR injury in a MI mouse model. TD peptide (1 mg/kg) was administered in mice subjected to MI (TD; n = 21), 5 min prior to reperfusion, and were clinically followed-up during 6 months after surgery. Plasma cTnI concentration evaluated 24 h post-MI was 70%-decreased in TD (n = 16) versus Ctrl (n = 20) mice (p***). Strain echocardiography highlighted a 24%-increase (p****) in the ejection fraction mean value in TD-treated (n = 12) versus Ctrl mice (n = 17) during the 6 month-period. Improved cardiac performance was associated to a 54%-decrease (p**) in left ventricular fibrosis at 6 months in TD (n = 16) versus Ctrl (n = 20). In conclusion, targeting the extrinsic pathway with TD peptide at the onset of reperfusion provided long-term cardioprotection in a mouse model of myocardial IR injury by improving post-MI cardiac performance and preventing cardiac remodeling.

Aims: Regulated cell death is a main contributor of myocardial ischaemia-reperfusion (IR) injury during acute myocardial infarction. In this context, targeting apoptosis could be a potent therapeutical strategy. In a previous study, we showed that DAXX (death-associated protein) was essential for transducing the FAS-dependent apoptotic signal during IR injury. The present study aims at evaluating the cardioprotective effects of a synthetic peptide inhibiting FAS:DAXX interaction., Methods and Results: An interfering peptide was engineered and then coupled to the Tat cell penetrating peptide (Tat-DAXXp). Its internalization and anti-apoptotic properties were demonstrated in primary cardiomyocytes. Importantly, an intravenous bolus injection of Tat-DAXXp (1 mg/kg) 5 min before reperfusion in a murine myocardial IR model decreased infarct size by 48% after 24 h of reperfusion. In addition, Tat-DAXXp was still efficient after a 30-min delayed administration, and was completely degraded and eliminated within 24 h thereby reducing risks of potential side effects. Importantly, Tat-DAXXp reduced mouse early post-infarction mortality by 67%. Mechanistically, cardioprotection was supported by both anti-apoptotic and pro-survival effects, and an improvement of myocardial functional recovery as evidenced in ex vivo experiments., Conclusions: Our study demonstrates that a single dose of Tat-DAXXp injected intravenously at the onset of reperfusion leads to a strong cardioprotection in vivo by inhibiting IR injury validating Tat-DAXXp as a promising candidate for therapeutic application., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Diabetic cardiomyopathy, especially myocardial ischemia reperfusion (I/R) injury, is a major cause of morbidity and mortality in type 2 diabetic patients. The increasing of basal p38 MAP Kinase (p38 MAPK) activation is a major factor that aggravates cardiac death on diabetic cardiomyopathy. In addition, metformin also shows cardio-protective effects on myocardial ischemia/reperfusion injury. In this study, we investigated the effect of the combination between metformin and p38 MAPK inhibitor (SB203580) in diabetic rats subjected to I/R injury. H9c2 cells were induced into a hyperglycemic condition and treated with metformin, SB203580 or the combination of metformin and SB203580. In addition, cells in both the presence and absence of drug treatment were subjected to simulated ischemia/reperfusion injury. Cell viability and cellular reactive oxygen species (ROS) were determined. Moreover, the Goto-Kakizaki (GK) rats were treated with metformin, SB203580, and the combination of metformin and SB203580 for 4 weeks. Diabetic parameters and cardiac functions were assessed. Finally, rat hearts were induced ischemia/reperfusion injury for the purpose of infarct size analysis and determination of signal transduction. A high-glucose condition did not reduce cell viability but significantly increased ROS production and significantly decreased cell viability after induced sI/R. Treatment using drugs was shown to reduce ROS generation and cardiac cell death. The GK rats displayed diabetic phenotype by increasing diabetic parameters and these parameters were significantly decreased when treated with drugs. Treatment with metformin or SB203580 could significantly reduce the infarct size. Interestingly, the combination of metformin and SB203580 could enhance cardio-protective ability. Myocardial I/R injury significantly increased p38 MAPK phosphorylation, Bax/Bcl-2 ratio and caspase-3 level. Treatment with drugs significantly decreased the p38 MAPK phosphorylation, Bax/Bcl-2 ratio, caspase-3 level and increased Akt phosphorylation. In conclusion, using the combination of metformin and SB203580 shows positive cardio-protective effects on diabetic ischemic cardiomyopathy.

Protease enzymes generated from injured cells and leukocytes are the primary cause of myocardial cell damage following ischemia/reperfusion (I/R). The inhibition of protease enzyme activity via the administration of particular drugs may reduce injury and potentially save patients' lives. The aim of the current study was to investigate the cardioprotective effects of treatment with recombinant human secretory leukocyte protease inhibitor (rhSLPI) on in vitro and ex vivo models of myocardial I/R injury. rhSLPI was applied to isolated adult rat ventricular myocytes (ARVMs) subjected to simulated I/R and to ex vivo murine hearts prior to I/R injury. Cellular injury, cell viability, reactive oxygen species (ROS) levels, and levels of associated proteins were assessed. The results demonstrated that administration of rhSLPI prior to or during sI/R significantly reduced the death and injury of ARVMs and significantly reduced intracellular ROS levels in ARVMs during H 2 O 2 stimulation. In addition, treatment of ARVMs with rhSLPI significantly attenuated p38 mitogen-activated protein kinase (MAPK) activation and increased the activation of Akt. Furthermore, pretreatment of ex vivo murine hearts with rhSLPI prior to I/R significantly decreased infarct size, attenuated p38 MAPK activation and increased Akt phosphorylation. The results of the current study demonstrated that treatment with rhSLPI induced a cardioprotective effect and reduced ARVM injury and death, intracellular ROS levels and infarct size. rhSLPI also attenuated p38 MAPK phosphorylation and activated Akt phosphorylation. These results suggest that rhSLPI may be developed as a novel therapeutic strategy of treating ischemic heart disease.

MLC901, a traditional Chinese medicine containing a cocktail of active molecules, both reduces cerebral infarction and improves recovery in patients with ischemic stroke. The aim of this study was to evaluate the acute and long-term benefits of MLC901 in ischemic and reperfused mouse hearts. Ex vivo, under physiological conditions, MLC901 did not show any modification in heart rate and contraction amplitude. However, upon an ischemic insult, MLC901 administration during reperfusion, improved coronary flow in perfused hearts. In vivo, MLC901 (4 µg/kg) intravenous injection 5 minutes before reperfusion provided a decrease in both infarct size (49.8%) and apoptosis (49.9%) after 1 hour of reperfusion. Akt and ERK1/2 survival pathways were significantly activated in the myocardium of those mice. In the 4-month clinical follow-up upon an additional continuous per os administration, MLC901 treatment decreased cardiac injury as revealed by a 45%-decrease in cTnI plasmatic concentrations and an improved cardiac performance assessed by echocardiography. A histological analysis revealed a 64%-decreased residual scar fibrosis and a 44%-increased vascular density in the infarct region. This paper demonstrates that MLC901 treatment was able to provide acute and long-term cardioprotective effects in a murine model of myocardial ischemia-reperfusion injury in vivo.

Small interfering RNAs (siRNAs) present a strong therapeutic potential because of their ability to inhibit the expression of any desired protein. Recently, we developed the retro-inverso amphipathic RICK peptide as novel non-covalent siRNA carrier. This peptide is able to form nanoparticles (NPs) by self-assembling with the siRNA resulting in the fully siRNA protection based on its protease resistant peptide sequence. With regard to an in vivo application, we investigated here the influence of the polyethylene glycol (PEG) grafting to RICK NPs on their in vitro and in vivo siRNA delivery properties. A detailed structural study shows that PEGylation did not alter the NP formation (only decrease in zeta potential) regardless of the used PEGylation rates. Compared to the native RICK:siRNA NPs, low PEGylation rates (≤20%) of the NPs did not influence their cellular internalization capacity as well as their knock-down specificity (over-expressed or endogenous system) in vitro. Because the behavior of PEGylated NPs could differ in their in vivo application, we analyzed the repartition of fluorescent labeled NPs injected at the one-cell stage in zebrafish embryos as well as their pharmacokinetic (PK) profile after administration to mice. After an intra-cardiac injection of the PEGylated NPs, we could clearly determine that 20% PEG-RICK NPs reduce significantly liver and kidney accumulation. NPs with 20% PEGylation constitutes a modular, easy-to-handle drug delivery system which could be adapted to other types of functional moieties to develop safe and biocompatible delivery systems for the clinical application of RNAi-based cancer therapeutics., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Aims: In a previous study using a genome-wide microarray strategy, we identified metabotropic glutamate receptor 1 (mGluR1) as a putative cardioprotective candidate in ischaemic postconditioning (PostC). In the present study, we investigated the role of cardiac mGluR1 receptors during cardioprotection against myocardial ischaemia-reperfusion injury in the mouse myocardium., Methods and Results: mGluR1 activation by glutamate administered 5 min before reperfusion in C57Bl/6 mice subjected to a myocardial ischaemia protocol strongly decreased both infarct size and DNA fragmentation measured at 24 h reperfusion. This cardioprotective effect was mimicked by the mGluR1 agonist, DHPG (10 μM), and abolished when glutamate was coinjected with the mGluR1 antagonist YM298198 (100 nM). Wortmannin (100 nM), an inhibitor of PI3-kinase, was able to prevent glutamate-induced cardioprotection. A glutamate bolus at the onset of reperfusion failed to protect the heart of mGluR1 knockout mice subjected to a myocardial ischaemia-reperfusion protocol, although PostC still protected the mGluR1 KO mice. Glutamate-treatment improved post-infarction functional recovery as evidenced by an echocardiographic study performed 15 days after treatment and by a histological evaluation of fibrosis 21 days post-treatment. Interestingly, restoration of functional mGluR1s by a PostC stimulus was evidenced at the transcriptional level. Since mGluR1s were localized at the surface membrane of cardiomyocytes, they might contribute to the cardioprotective effect of ischaemic PostC as other Gq-coupled receptors., Conclusion: This study provides the first demonstration that mGluR1 activation at the onset of reperfusion induces cardioprotection and might represent a putative strategy to prevent ischaemia-reperfusion injury., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.)

Erythropoietin (EPO) is the main hormone that regulates erythropoiesis. Beyond its well-known hematopoietic action, EPO has diverse cellular effects in non-hematopoietic tissues. It has been shown to inhibit apoptosis by activating pro-survival pathways in the myocardium, to mobilize endothelial progenitor cells and to inhibit migration of inflammatory cells. EPO has also been shown to have potent pro-angiogenic properties. Numerous experimental data support the cardioprotective effects of EPO in animal models of acute myocardial infarct (AMI). However, these findings are not supported by recent clinical trials designed to investigate the safety and efficacy of EPO in patients with AMI. In this article, we begin by providing a comprehensive review of the cardioprotective effects of EPO in experimental animal models and the molecular mechanisms underlying these effects. We then discuss the EPO data obtained through clinical trials. We compare similarities and differences between the animal and human studies as well as between the different clinical studies in terms of sample size and study design including the dose, the route and the timing of administration as well as confounding factors such as comorbidities and concomitant treatments. Finally, we question the gap between the experimental and the translational clinical data and propose further developments to address these discrepancies and clearly evaluate the role of EPO in the clinical setting of MI.

Background: Several trials investigating erythropoietin as a novel cytoprotective agent in myocardial infarction (MI) failed to translate promising preclinical results into the clinical setting. These trials could have missed crucial events occurring in the first few minutes of reperfusion. Our study differs by earlier intracoronary administration of a longer-acting erythropoietin analogue at the onset of reperfusion., Aim: To evaluate the ability of intracoronary administration of darbepoetin-alpha (DA) at the very onset of the reperfusion, to decrease infarct size (IS)., Methods: We randomly assigned 56 patients with acute ST-segment elevation MI to receive an intracoronary bolus of DA 150 μg (DA group) or normal saline (control group) at the onset of reflow obtained by primary percutaneous coronary intervention (PCI). IS and area at risk (AAR) were evaluated by biomarkers, cardiac magnetic resonance (CMR) and validated angiographical scores., Results: There was no difference between groups regarding duration of ischemia, Thrombolysis in Myocardial Infarction flow grade at admission and after PCI, AAR size and extent of the collateral circulation, which are the main determinants of IS. The release of creatine kinase was not significantly different between the two groups even when adjusted to AAR size. Between 3-7 days and at 3 months, the area of hyperenhancement on CMR expressed as a percentage of the left ventricular myocardium was not significantly reduced in the DA group even when adjusted to AAR size., Conclusion: Early intracoronary administration of a longer-acting erythropoietin analogue in patients with acute MI at the time of reperfusion does not significantly reduce IS., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Recognition that inflammation may contribute to the pathogenesis of various cardiac diseases has naturally led to the evaluation of the therapeutic potential of a range of anti-inflammatory approaches. Unfortunately, results in most settings have been disappointing. The majority of novel approaches fail despite promising preclinical data, partly attributable to off-target effects. The purpose of this review, focused on inflammation following acute myocardial ischemia, is to give a brief overview of the new insights regarding research on pro-inflammatory signaling cascades that could be targeted for cardioprotective therapeutic developments.

Acute myocardial infarction (AMI) is a frequent and disabling disease, which is the first cause of cardiovascular mortality worldwide. Infarct size is a major determinant of myocardial functional recovery and mortality after AMI. Limitation of infarct size thus appears as an appropriate strategy to prevent post-ischemic heart failure and improve survival. Reperfusion is the only treatment recommended to reduce infarct size but despite obvious benefits, it may also have deleterious effects called ischemia-reperfusion (IR) injury including myocyte cell death. Proteins involved in the apoptosis cascade generally interact over large surfaces lacking well-defined pockets. Therefore, inhibitory peptides are optimal biomolecules to target these large protein surfaces, they are often more selective to their target than conventional small organic molecules, and they can be tailored for optimal affinity or desired metabolic property. Since peptides do not cross freely biological membranes, they are generally administered in association with cell penetrating peptides (CPPs) and with homing peptides (HPs) for selective organs or tissues targeting. As a first approach in vivo, we made use of the already known BH4 peptidic inhibitor of the mitochondrial apoptotic pathway, which showed cardioprotective properties in a murine model of AMI after a single bolus of intravenous administration. More importantly, similar peptidic strategies and tools are likely to be adaptable to many other situations in which cells have to be protected from apoptosis such as stroke or organ transplantation.

Ischemic postconditioning applied at the onset of reperfusion reduces myocardial infarction in both animals and humans. Our recent study on the mouse myocardium showed for the first time that delayed postconditioning (applied up to 30 min after the onset of reperfusion) can decrease infarct size. The existence of a longer cardioprotection window is conceptually relevant for clinical application and also in the case of a pharmacological strategy., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Unlabelled: PURPOSE AND MEDICAL HYPOTHESIS: Rest is usually recommended in acute pericarditis, as it could help to lower heart rate (HR) and contribute to limit "mechanical inflammation". Whether HR on admission could be correlated and perhaps participate to inflammation has not been reported., Methods: Between March 2007 and February 2010, we conducted a retrospective study on all patients admitted to our center for acute pericarditis. Diagnosis criteria included two of the following ones: typical chest pain, friction rub, pericardial effusion on cardiac echography, or typical electrocardiogram (ECG) findings. Primary endpoint was biology: CRP on admission, on days 1, 2, 3, and especially peak., Results: We included 73 patients. Median age was 38 years (interquartiles 28-51) and median hospitalization duration was 2.0 days (1.5-3.0). Median heart rate was 88.0 beats per minute (bpm) on admission (interquartiles 76.0-100.0) and 72.0 on discharge (65.0-80.0). Heart rate on admission was significantly correlated with CRP peak (p<0.001), independently of temperature on admission, hospitalization duration and age. Recurrences occurred within 1 month in 32% of patients. Heart rate on hospital discharge was correlated with recurrence, independently of age., Conclusion: In acute pericarditis, heart rate on admission is independently correlated with CRP levels and heart rate on discharge seems to be independently correlated to recurrence. This could suggest a link between heart rate and pericardial inflammation., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Aims: Myocardial infarction leads to heart failure and death. Ischaemic preconditioning (PreC) and postconditioning (PostC) reduce infarct size in animal models and human. Zac1 was identified as the only gene related to apoptosis and jointly down-regulated upon PreC and PostC. The aim of our study was to investigate the role of Zac1 down-regulation during ischaemia-reperfusion (I/R) in vivo., Methods and Results: C57BL/6 mice were submitted to myocardial I/R injury, PreC, or PostC protocols. QPCR and immunochemistry showed that Zac1 expression was down-regulated both at the transcriptional and the protein levels upon PreC and PostC. Zac1(-/-) Knockout mice (n = 7) developed smaller infarcts (54%) than Zac1(+/+) littermates (n = 8) and decreased apoptosis (61.7%) in the ischaemic part of the left ventricle during I/R (Zac1(-/-), n = 6 vs. Zac1(+/+), n = 7; P = 0.0012). Mutants showed under control conditions a decrease of 53.9% in mRNA of Daxx, a pro-apoptotic protein playing a key role in I/R injuries (4.81 ± 0.77, n = 4 Zac1(-/-) mice vs. 10.44 ± 3.5, n = 7 Zac1(+/+) mice; P = 0.0121)., Conclusion: Our study shows for the first time that Zac1 is down-regulated both at the transcriptional and protein levels upon PreC and PostC in wild-type mice. Moreover, inactivation of Zac1 in vivo is associated with a decreased amount of Daxx transcripts and, upon I/R injury, decreased infarct size and apoptosis. Altogether, our results show that Zac1 down-regulation plays a key role during cardioprotection against I/R injury and support the concept that cardioprotection regulates a network of interacting pro-apoptotic genes including Zac1 and Daxx.

There is an obvious need to develop pharmacological strategies to protect the heart in patients suffering from acute myocardial infarction. Apoptosis was evidenced as a main contributor of myocardial ischemia-reperfusion (IR) injury. Our cardioprotective strategy was based on the use of four cell penetrating peptides (CPP: Tat, (RXR)4, Bpep and Pip2b) which were conjugated to the BH4-peptide, derived from the BH4 domain of the Bcl-xL anti-apoptotic protein. These CPP-BH4 conjugates were able to reduce staurosporine-induced apoptosis in primary cardiomyocytes in vitro. Although Pip2b-BH4 was more efficient in terms of cellular uptake, it was as efficient as Tat-BH4 for its anti-apoptotic activity. As required for potential therapeutic application their cardioprotective effects were evaluated in an in vivo mouse model of myocardial IR injury. Our results clearly show that a single low dose (1 mg/kg) injection of Tat-BH4 and Pip2b-BH4 administered intravenously 5 min before reperfusion was able to drastically reduce infarct size (~47%) and to inhibit apoptosis (~60%) in the left ventricle of treated mice. Importantly, these effects are not observed following the injection of CPP alone or scrambled version of BH4. This study evidences that the Pip2b CPP, designed for oligonucleotides translocation, as well as the widely used natural Tat CPP exhibit similar efficacy in vivo to deliver BH4 anti-apoptotic peptide to the reperfused myocardium and may thus become useful therapeutic tools to treat acute myocardial infarction in the clinical setting., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: Reperfusion during acute myocardial infarction remains the best treatment for reducing infarct size. Postconditioning, applied at the onset of reperfusion, reduces myocardial infarction both in animals and humans. The objective of this study was to identify the time delay to apply postconditioning at reperfusion, allowing preservation of cardioprotection in the mouse myocardium. This is a major issue in the management of acute myocardial infarction patients., Methods and Results: Mice were subjected to 40 minutes of ischemia and 60 minutes of reperfusion (IR(60')). Postconditioning protocols corresponding to repetitive ischemia (3 cycles of 1 minute of ischemia and 1 minute of reperfusion) were applied during early reperfusion at various time durations (Δt) after reopening of the coronary artery (Δt=10 seconds, 1, 5, 10, 15, 20, 30, and 45 minutes; PostC(Δt)). Infarct size/area at risk was reduced by 71% in PostC(Δ1) compared with IR(60') mice (P=5×10(-6)). There was a linear correlation (r(2)=0.91) between infarct size and Δt, indicating that the cardioprotective effect of delayed postconditioning was progressively attenuated when Δt time increased. The protective effect of PostC(Δ1) and PostC(Δ15) was still effective when the duration of reperfusion was prolonged to 24 hours (IR(24 hours); PostC(Δ1) and PostC(Δ15) versus IR(24 hours), P=0.001). Similar results were obtained for internucleosomal DNA fragmentation and lactate dehydrogenase release., Conclusions: This study in our in vivo mouse model of myocardial IR shows for the first time that delaying the intervention of postconditioning to 30 minutes does not abrogate the cardioprotective effect of postconditioning. This finding provides evidence that the time window of protection afforded by postconditioning may be larger than initially reported.

Background: Apoptosis has been described extensively in acute myocardial infarction and chronic heart failure. Because Daxx (death-associated protein) appears to be essential for stress-induced cell death and acts as an antisurvival molecule, we tested the hypothesis that Daxx is involved in myocardial ischemia/reperfusion-induced cell death in vivo., Methods and Results: Transgenic mice overexpressing a dominant-negative form of Daxx (Daxx-DN) under the control of the beta-actin promoter and control wild-type mice underwent an ischemia/reperfusion protocol: 40 minutes of left coronary artery occlusion and 60 minutes of reperfusion. Area at risk and infarct size were measured after dual staining by triphenyltetrazolium chloride and phthalocyanine blue dye. Apoptosis was measured in the ischemic versus the nonischemic part of the left ventricle by terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labeling staining, enzyme-linked immunosorbent assay, and Western blotting of caspase-3, caspase-8, and poly(ADP-ribose) polymerase. The mitogen-activated protein kinase status was investigated by Western blot analysis. Comparison between groups was assessed by ANOVA or Student t test (statistical significance: P<0.05). Left ventricle tissues from transgenic mice expressed Daxx-DN at the protein level. Area at risk/left ventricle values were comparable among groups. Infarct size/area at risk was 45% reduced in Daxx-DN versus wild-type mice (P<0.001). This cardioprotection was maintained for a 4-hour reperfusion. Ischemia/reperfusion-induced apoptosis was significantly decreased and ERK1/2 prosurvival pathway was activated in ischemic Daxx-DN hearts., Conclusions: Our study clearly indicates that Daxx participates in myocardial ischemia/reperfusion proapoptotic signaling in vivo.

The exchange factor directly activated by cAMP (Epac) is a newly discovered direct target for cAMP and a guanine-nucleotide exchange factor for the small GTPase Rap. Little is known about the neuronal functions of Epac. Here we show that activation of Epac by specific cAMP analogs or by the pituitary adenylate cyclase-activating polypeptide induces a potent activation of the Ca2+-sensitive big K+ channel, slight membrane hyperpolarization, and increased after-hyperpolarization in cultured cerebellar granule cells. These effects involve activation of Rap and p38 MAPK, which mobilizes intracellular Ca2+ stores. These findings reveal a cAMP Epac-dependent and protein kinase A-independent signaling cascade that controls neuronal excitability.

Aims: BPH is characterized by uncontrolled proliferation and increased contractility of prostatic smooth muscle cells. The activation of alpha1-adrenoceptors (alpha1-AR) seems involved in the latter event, but the lack of in vitro models expressing these receptors has hampered a more specific characterization of their role. In order to do so, we attempted to develop a new model of rabbit cultured prostatic stromal cells (PSC) in a non-proliferative and differentiated state., Methods: The expression of cytoskeletal and stromal markers was confirmed by immunohistochemistry on primary cultured PSC. Alpha1-AR subtype expression was assessed by RT-PCR, while receptor coupling to the ERK1/ERK2 and calcium pathways was studied by Western Blot and Fura-2 calcium imaging, respectively., Results: Cells grown under non-proliferative conditions displayed a differentiated phenotype, with expression of contractile cytoskeletal and stromal proteins. Furthermore, the alpha1A-AR was shown to activate ERK1/ERK2 as well as calcium signaling., Conclusion: These results emphasize the interest of this model for the characterization of PSC adrenergic regulation, in particular through the little-known alpha1A-AR., ((c) 2005 Wiley-Liss, Inc.)

Objective: Although aldosterone has been implicated in the pathogenesis of cardiac hypertrophy and heart failure, its cellular mechanism of action on cardiomyocyte function is not yet completely elucidated. This study was designed to investigate the effect of aldosterone on calcium channel expression and cardiomyocyte contraction frequency., Methods: Cultured neonatal rat ventricular cardiomyocytes were stimulated in vitro with 1 micromol/L aldosterone for 24 h. Calcium currents were then measured with the patch clamp technique, while calcium channel expression was assessed by real-time RT-PCR., Results: In the present study, we show that aldosterone increases Ca2+ currents by inducing channel expression. Indeed, aldosterone led to a substantial increase of L- and T-type Ca2+ current amplitudes, and we found a concomitant 55% increase of the mRNA coding for alpha1C and beta2 subunits of cardiac L channels. Although T-type currents were relatively small under control conditions, they increased 4-fold and T channel alpha1H isoform expression rose in the same proportion after aldosterone treatment. Because T channels have been implicated in the modulation of membrane electrical activity, we investigated whether aldosterone affects the beating frequency of isolated cardiomyocytes. In fact, aldosterone dose-dependently increased the spontaneous beating frequency more than 4-fold. This effect of aldosterone was prevented by actinomycin D and spironolactone and reduced by RU486, suggesting a mixed mineralocorticoid/glucocorticoid receptor-dependent transcriptional mechanism. Moreover, inhibition of T currents with Ni2+ or mibefradil significantly reduced beating frequency towards control values, while conditions affecting L-type currents completely blocked contractions., Conclusion: Aldosterone modulates the expression of cardiac voltage-operated Ca2+ channels and accelerates beating in cultured neonatal rat ventricular myocytes. This chronotropic action of aldosterone appears to be linked to increased T channel activity and could contribute to the deleterious effect of an excess of this steroid in vivo on cardiac function.

Morphine has cardioprotective effects against ischemic-reperfusion injuries. This study investigates whether morphine could mimic the antiapoptotic effect of preconditioning using a model of cultured neonatal rat cardiomyocytes subjected to metabolic inhibition (MI). To quantify MI-induced apoptosis, DNA fragmentation and mitochondrial cytochrome c release levels were measured by ELISA. MI-dependent DNA fragmentation was prevented by both Z-VAD-fmk (20 microM), a pan-caspase inhibitor, and cyclosporine A (CsA; 5 microM), a mitochondrial pore transition blocker, added during MI (36% and 54% decrease, respectively). MI-dependent cytochrome c release was not blocked by Z-VAD-fmk but was decreased (38%) by CsA during MI. Metabolic preconditioning (MIP) and preconditioning with morphine (1 microM) were also assessed. MI-dependent DNA fragmentation and cytochrome c release were prevented by MIP (40% and 45% decrease, respectively) and morphine (34% and 45%, respectively). The antiapoptotic effect of morphine was abolished by naloxone (10 nM), a nonselective opioid receptor antagonist, or xestospongin C (XeC, 400 nM), an inhibitor of inositol (1,4,5)-trisphosphate [Ins(1,4,5)P(3)]-mediated Ca(2+) release. Ca(2+) preconditioning, induced by increasing extracellular Ca(2+) from 1.8 to 3.3 mM, mimicked the antiapoptotic effect of morphine on DNA fragmentation (24% decrease) and cytochrome c release (57% decrease). This effect mediated by extracellular Ca(2+) was also abolished by XeC. Measurements of intracellular Ca(2+) concentration using fura-2 microspectrofluorimetry showed that morphine induces Ins(1,4,5)P(3)-dependent Ca(2+) transients abolished by 2-aminoethoxydiphenyl borate (2-APB), a cell-permeable Ins(1,4,5)P(3) antagonist. These results suggest that morphine preconditioning prevents simulated ischemia-reperfusion-induced apoptosis via an Ins(1,4,5)P(3) signaling pathway in rat ventricular myocytes.