Efficacy of a cysteine protease inhibitor compared with enalapril in murine heart failure models.

Cysteine proteases calpains contribute to heart failure (HF), but it remains unknown whether their inhibition provides any benefit compared to standard pharmacological treatment for HF. Here, we characterize the pharmacological properties of NPO-2270 (NPO) as a potent inhibitor of cysteine proteases. Then, we describe that acute administration of NPO in rodent models of transient ischemia at the time of reperfusion reduces myocardial infarction, while its chronic oral administration attenuates adverse remodeling and cardiac dysfunction induced by ischemic and non-ischemic pathological stimuli more effectively than enalapril when given at the same dose.

Connexin 43 modulates reverse electron transfer in cardiac mitochondria from inducible knock-out Cx43 mice by altering the coenzyme Q pool.

Succinate accumulates during myocardial ischemia and is rapidly oxidized during reperfusion, leading to reactive oxygen species (ROS) production through reverse electron transfer (RET) from mitochondrial complex II to complex I, and favoring cell death. Given that connexin 43 (Cx43) modulates mitochondrial ROS production, we investigated whether Cx43 influences RET using inducible knock-out Cx43 mice. Oxygen consumption, ROS production, membrane potential and coenzyme Q (CoQ) pool were analyzed in subsarcolemmal (SSM, expressing Cx43) and interfibrillar (IFM) cardiac mitochondria isolated from wild-type Cx43 mice and Cx43 knock-out animals treated with 4-hydroxytamoxifen (4OHT).

Long-Term Protective Effects of Succinate Dehydrogenase Inhibition during Reperfusion with Malonate on Post-Infarction Left Ventricular Scar and Remodeling in Mice.

Succinate dehydrogenase inhibition with malonate during initial reperfusion reduces myocardial infarct size in both isolated mouse hearts subjected to global ischemia and in in situ pig hearts subjected to transient coronary ligature. However, the long-term effects of acute malonate treatment are unknown. Here, we investigated whether the protective effects of succinate dehydrogenase inhibition extend to a reduction in scar size and adverse left ventricular remodeling 28 days after myocardial infarction.

TRPV4 Channels Promote Pathological, but Not Physiological, Cardiac Remodeling through the Activation of Calcineurin/NFAT and TRPC6.

TRPV4 channels, which respond to mechanical activation by permeating Ca into the cell, may play a pivotal role in cardiac remodeling during cardiac overload. Our study aimed to investigate TRPV4 involvement in pathological and physiological remodeling through Ca-dependent signaling. TRPV4 expression was assessed in heart failure (HF) models, induced by isoproterenol infusion or transverse aortic constriction, and in exercise-induced adaptive remodeling models.

Spontaneous reperfusion enhances succinate concentration in peripheral blood from stemi patients but its levels does not correlate with myocardial infarct size or area at risk.

Succinate is enhanced during initial reperfusion in blood from the coronary sinus in ST-segment elevation myocardial infarction (STEMI) patients and in pigs submitted to transient coronary occlusion. Succinate levels might have a prognostic value, as they may correlate with edema volume or myocardial infarct size. However, blood from the coronary sinus is not routinely obtained in the CathLab.

Calpains as Potential Therapeutic Targets for Myocardial Hypertrophy.

Despite advances in its treatment, heart failure remains a major cause of morbidity and mortality, evidencing an urgent need for novel mechanism-based targets and strategies. Myocardial hypertrophy, caused by a wide variety of chronic stress stimuli, represents an independent risk factor for the development of heart failure, and its prevention constitutes a clinical objective. Recent studies performed in preclinical animal models support the contribution of the Ca-dependent cysteine proteases calpains in regulating the hypertrophic process and highlight the feasibility of their long-term inhibition as a pharmacological strategy.

Defective dimerization of FoF1-ATP synthase secondary to glycation favors mitochondrial energy deficiency in cardiomyocytes during aging.

Aged cardiomyocytes develop a mismatch between energy demand and supply, the severity of which determines the onset of heart failure, and become prone to undergo cell death. The FoF1-ATP synthase is the molecular machine that provides >90% of the ATP consumed by healthy cardiomyocytes and is proposed to form the mitochondrial permeability transition pore (mPTP), an energy-dissipating channel involved in cell death. We investigated whether aging alters FoF1-ATP synthase self-assembly, a fundamental biological process involved in mitochondrial cristae morphology and energy efficiency, and the functional consequences this may have.

Aging Impairs Reverse Remodeling and Recovery of Ventricular Function after Isoproterenol-Induced Cardiomyopathy.

Information about heart failure with reduced ejection fraction (HFrEF) in women and the potential effects of aging in the female heart is scarce. We investigated the vulnerability to develop HFrEF in female elderly mice compared to young animals, as well as potential differences in reverse remodeling. First, HF was induced by isoproterenol infusion (30 mg/kg/day, 28 days) in young (10-week-old) and elderly (22-month-old) female mice.

Cardiac fibroblasts display endurance to ischemia, high ROS control and elevated respiration regulated by the JAK2/STAT pathway.

Cardiovascular diseases are the leading cause of death globally and more than four out of five cases are due to ischemic events. Cardiac fibroblasts (CF) contribute to normal heart development and function, and produce the post-ischemic scar. Here, we characterize the biochemical and functional aspects related to CF endurance to ischemia-like conditions.

Implications of Iron Deficiency in STEMI Patients and in a Murine Model of Myocardial Infarction.

In patients with a first anterior ST-segment elevation myocardial infarction treated with primary percutaneous coronary intervention, iron deficiency (ID) was associated with larger infarcts, more extensive microvascular obstruction, and higher frequency of adverse left ventricular remodeling as assessed by cardiac magnetic resonance imaging. In mice, an ID diet reduced the activity of the endothelial nitric oxide synthase/soluble guanylate cyclase/protein kinase G pathway in association with oxidative/nitrosative stress and increased infarct size after transient coronary occlusion. Iron supplementation or administration of an sGC activator before ischemia prevented the effects of the ID diet in mice.

Citric Acid Cycle Metabolites Predict Infarct Size in Submitted to Transient Coronary Artery Occlusion and Treated with Succinate Dehydrogenase Inhibitors or Remote Ischemic Perconditioning.

Succinate dehydrogenase (SDH) inhibition with malonate during reperfusion reduced myocardial infarction in animals, whereas its endogenous substrate, succinate, is detected in plasma from STEMI patients. We investigated whether protection by SDH inhibition is additive to that of remote ischemic perconditioning (RIC) in submitted to transient coronary artery occlusion, and whether protective maneuvers influence plasma levels of citric acid cycle metabolites. Forty were submitted to 40 min coronary occlusion and reperfusion, and allocated to four groups (controls, sodium malonate 10 mmol/L, RIC, and malonate + RIC).

Effect of COMBinAtion therapy with remote ischemic conditioning and exenatide on the Myocardial Infarct size: a two-by-two factorial randomized trial (COMBAT-MI).

Remote ischemic conditioning (RIC) and the GLP-1 analog exenatide activate different cardioprotective pathways and may have additive effects on infarct size (IS). Here, we aimed to assess the efficacy of RIC as compared with sham procedure, and of exenatide, as compared with placebo, and the interaction between both, to reduce IS in humans. We designed a two-by-two factorial, randomized controlled, blinded, multicenter, clinical trial.

Macrophages promote endothelial-to-mesenchymal transition via MT1-MMP/TGFβ1 after myocardial infarction.

Macrophages (Mφs) produce factors that participate in cardiac repair and remodeling after myocardial infarction (MI); however, how these factors crosstalk with other cell types mediating repair is not fully understood. Here we demonstrated that cardiac Mφs increased the expression of (MT1-MMP) 7 days post-MI. We selectively inactivated the gene in Mφs using a genetic strategy (:-Cre).

Connexin 43 Deficiency Is Associated with Reduced Myocardial Scar Size and Attenuated TGFβ1 Signaling after Transient Coronary Occlusion in Conditional Knock-Out Mice.

Previous studies demonstrated a reduction in myocardial scar size in heterozygous Cx43 mice subjected to permanent coronary occlusion. However, patients presenting with ST segment elevation myocardial infarction often undergo rapid coronary revascularization leading to prompt restoration of coronary flow. Therefore, we aimed to assess changes in scar size and left ventricular remodeling following transient myocardial ischemia (45 min) followed by 14 days of reperfusion using Cx43 (controls) and Cx43 inducible knock-out (Cx43 content: 50%) mice treated with vehicle or 4-hydroxytamoxifen (4-OHT) to induce a Cre-ER(T)-mediated global deletion of the Cx43 floxed allele.

Degradation of GRK2 and AKT is an early and detrimental event in myocardial ischemia/reperfusion.

Background: Identification of signaling pathways altered at early stages after cardiac ischemia/reperfusion (I/R) is crucial to develop timely therapies aimed at reducing I/R injury. The expression of G protein-coupled receptor kinase 2 (GRK2), a key signaling hub, is up-regulated in the long-term in patients and in experimental models of heart failure. However, whether GRK2 levels change at early time points following myocardial I/R and its functional impact during this period remain to be established.

High-fat diet improves tolerance to myocardial ischemia by delaying normalization of intracellular PH at reperfusion.

Reports on the effect of obesity on the myocardial tolerance to ischemia are contradictory. We have described that obesity induced by high-fat diet (HFD) reduces infarct size in B6D2F1 mice submitted to transient coronary occlusion. In this study, we analysed the mechanism by which dietary obesity modifies the susceptibility to myocardial ischemia and the robustness of this effect.

Calpains mediate isoproterenol-induced hypertrophy through modulation of GRK2.

Inhibition of the Ca-dependent proteases calpains attenuates post-infarction remodeling and heart failure. Recent data suggest that calpain activity is elevated in non-ischemic cardiomyopathies and that upregulation of the key cardiac G-protein-coupled receptor kinase 2 (GRK2) signaling hub promotes cardiac hypertrophy. However, the functional interactions between calpains and GRK2 in this context have not been explored.

Early regional wall distension is strongly associated with vulnerability to ventricular fibrillation but not arrhythmia triggers following coronary occlusion in vivo.

Wall stress may favor ischemic ventricular arrhythmias, yet its association with ventricular fibrillation (VF) or ventricular ectopy has been inconsistent among studies and its potential arrhythmogenicity across the cardiac cycle is unclear. In 91 open-chest pigs undergoing 40-50 min left anterior descending artery occlusion, we assessed the association between diastolic or systolic distension of the ischemic area and the incidence of ventricular premature beats (VPBs) and VF. End-diastolic segment length (EDL) and systolic bulging ([maximum systolic length-EDL] × 100/EDL) were measured by ultrasonic crystals.

Delayed, oral pharmacological inhibition of calpains attenuates adverse post-infarction remodelling.

Unlabelled: Calpains activate during myocardial ischemia-reperfusion and contribute to reperfusion injury. Studies in transgenic animals with altered calpain/calpastatin system subjected to permanent ischemia suggest that calpains are also involved in post-infarction remodelling and heart failure.

Aims: To determine whether delayed oral administration of the calpain inhibitor SNJ-1945 reduces adverse myocardial remodelling and dysfunction following transient coronary occlusion.

Measuring Water Distribution in the Heart: Preventing Edema Reduces Ischemia-Reperfusion Injury.

Background: Edema is present in many heart diseases, and differentiation between intracellular (ICW) and extracellular (ECW) myocardial water compartments would be clinically relevant. In this work we developed a magnetic resonance imaging-based method to differentiate ICW and ECW and applied it to analyze ischemia-reperfusion-induced edema.

Methods And Results: Isolated rat hearts were perfused with gadolinium chelates as a marker of extracellular space.

Effect of high fat diet on pulmonary expression of parathyroid hormone-related protein and its downstream targets.

Aims: Parathyroid hormone-related protein (PTHrP) is involved in lung development and surfactant production. The latter one requires a paracrine interaction between type II alveolar cells and lipofibroblasts in which leptin triggers PTHrP-induced effects. Whether increased plasma leptin levels, as they occur in high fat diet, modify the expression of PTHrP remains unclear.

Ischaemic conditioning and targeting reperfusion injury: a 30 year voyage of discovery.

To commemorate the auspicious occasion of the 30th anniversary of IPC, leading pioneers in the field of cardioprotection gathered in Barcelona in May 2016 to review and discuss the history of IPC, its evolution to IPost and RIC, myocardial reperfusion injury as a therapeutic target, and future targets and strategies for cardioprotection. This article provides an overview of the major topics discussed at this special meeting and underscores the huge importance and impact, the discovery of IPC has made in the field of cardiovascular research.

Studies on the role of apoptosis after transient myocardial ischemia: genetic deletion of the executioner caspases-3 and -7 does not limit infarct size and ventricular remodeling.

Although it is widely accepted that apoptosis may contribute to cell death in myocardial infarction, experimental evidence suggests that adult cardiomyocytes repress the expression of the caspase-dependent apoptotic pathway. The aim of this study was to analyze the contribution of caspase-mediated apoptosis to myocardial ischemia-reperfusion injury. Cardiac-specific caspase-3 deficient/full caspase-7-deficient mice (Casp3/7DKO) and wild type control mice (WT) were subjected to in situ ischemia by left anterior coronary artery ligation for 45 min followed by 24 h or 28 days of reperfusion.

Executioner Caspase-3 and 7 Deficiency Reduces Myocyte Number in the Developing Mouse Heart.

Executioner caspase-3 and -7 are proteases promoting cell death but non-apoptotic roles are being discovered. The heart expresses caspases only during development, suggesting they contribute to the organ maturation process. Therefore, we aimed at identifying novel functions of caspases in heart development.

Combination therapy with remote ischaemic conditioning and insulin or exenatide enhances infarct size limitation in pigs.

Aims: Remote ischaemic conditioning (RIC) has been shown to reduce myocardial infarct size in patients. Our objective was to investigate whether the combination of RIC with either exenatide or glucose-insulin-potassium (GIK) is more effective than RIC alone.

Methods And Results: Pigs were submitted to 40 min of coronary occlusion followed by reperfusion, and received (i) no treatment, (ii) one of the following treatments: RIC (5 min ischemia/5 min reperfusion × 4), GIK, or exenatide (at doses reducing infarct size in clinical trials), or (iii) a combination of two of these treatments (RIC + GIK or RIC + exenatide).