Cardioprotective Signaling Pathways Research Articles

Abstract Tu136: HIF-1α a novel therapeutic target to reduce Cardiac Ischemia Reperfusion Injury during AMI

Acute myocardial infarction (AMI) is a major cause of mortality worldwide. In preclinical models of AMI, using a trans-valvular pump (TVP) to reduce left ventricular (LV) workload for 30 minutes before reperfusion reduces infarct size by 50%. The mechanisms underlying the cardioprotective effect of LV unloading remain poorly understood. Hypoxia inducible factor 1-alpha (HIF-1α) is an oxygen-sensitive transcription factor that activates cardioprotective signaling pathways, improves cell survival and mitochondrial function during myocardial ischemia. We hypothesized that LV unloading limits myocardial injury by activating hypoxia inducible factor 1-a (HIF-1α). To explore the effect of LV unloading on HIF-1α stabilization during ischemia, we performed left anterior descending artery (LAD) occlusion for a total of 120 minutes in adult swine in the presence and absence of LV unloading and further 180 minutes of reperfusion was performed following 120 minutes of LAD occlusion. Trans-valvular unloading activation significantly decreased infarct size both during ischemia (IS/AAR: 4.78±4 % vs 1.5±3%) and post reperfusion when compared ischemia alone and IR alone groups (36.04±8.39 % vs 16.02±3.52 %, p<0.0001) respectively. Interestingly, HIF-1α stabilization is significantly reduced with LV unloading during ischemia and significantly increased post reperfusion in the infarct zone of the swine model of AMI. To test whether HIF1a is necessary for cardioprotection with LV unloading, adult swine were treated with intracoronary delivery of the HIF-1α inhibitor (2-methoxyestradiol; 2ME) before reperfusion. Compared to TVP activation for 30 minutes before reperfusion, addition of 2ME abolished the cardioprotective effect of TVP resulting in increased infarct size (16.03% vs 35.86% p<0.03) and decreased HIF-1a stabilization. Stabilizing HIF-1α post-reperfusion by using a well know HIF-1a stabilizing agent Roxadustat, immediately before reperfusion significantly decreased infarct size in both with and without TVP groups compared to IRI alone. Treatment with Roxadustat also preserved mitochondrial function and increased RISK signaling. We report the novel finding that stabilizing HIF-1a activity before reperfusion plays a critical role in reducing Infarct size in preclinical model of AMI.

Circulating GDF11 exacerbates myocardial injury in mice and associates with increased infarct size in humans.

The heart rejuvenating effects of circulating growth differentiation factor 11 (GDF11), a transforming growth factor-β superfamily member that shares 90% homology with myostatin (MSTN), remains controversial. Here, we aimed to probe the role of GDF11 in acute myocardial infarction (MI), a frequent cause of heart failure and premature death during ageing. In contrast to endogenous Mstn, myocardial Gdf11 declined during the course of ageing and was particularly reduced following ischaemia/reperfusion (I/R) injury, suggesting a therapeutic potential of GDF11 signalling in MI. Unexpectedly, boosting systemic Gdf11 by recombinant GDF11 delivery (0.1 mg/kg body weight over 30 days) prior to myocardial I/R augmented myocardial infarct size in C57BL/6 mice irrespective of their age, predominantly by accelerating pro-apoptotic signalling. While intrinsic cardioprotective signalling pathways remained unaffected by high circulating GDF11, targeted transcriptomics and immunomapping studies focusing on GDF11-associated downstream targets revealed attenuated Nkx2-5 expression confined to CD105-expressing cells, with pro-apoptotic activity, as assessed by caspase-3 levels, being particularly pronounced in adjacent cells, suggesting an indirect effect. By harnessing a highly specific and validated liquid chromatography-tandem mass spectrometry-based assay, we show that in prospectively recruited patients with MI circulating GDF11 but not MSTN levels incline with age. Moreover, GDF11 levels were particularly elevated in those at high risk for adverse outcomes following the acute event, with circulating GDF11 emerging as an independent predictor of myocardial infarct size, as estimated by standardized peak creatine kinase-MB levels. Our data challenge the initially reported heart rejuvenating effects of circulating GDF11 and suggest that high levels of systemic GDF11 exacerbate myocardial injury in mice and humans alike. Persistently high GDF11 levels during ageing may contribute to the age-dependent loss of cardioprotective mechanisms and thus poor outcomes of elderly patients following acute MI.

The mechanism and targeted intervention of the HIF-1 pathway in improving atherosclerotic heart's sensitivity to ischemic postconditioning

BackgroundIPoC possesses a preventive effect against IR injury in healthy myocardium, but IPoC's protective effect on atherosclerotic myocardium is controversial. The current investigation aims to determine whether IPoC remains protective in atherosclerotic myocardium subjected to ischemia-reperfusion (IR) injury; to explore the specific mechanisms by which IPoC exerts cardioprotection; to explore whether HIF-1 upregulation combined with IPoC could further the provide cardioprotection; and to gaze at the specific mechanism whereby combined treatment expert the cardioprotection. MethodsApoE−/− mice fed with a high-fat diet (HFD) were used to develop a model of atherosclerosis. The myocardial IR model was induced by occlusion of the left anterior descending (LAD) artery for 45 min, followed by reperfusion for 120 min. The protection of IPoC in both healthy and atherosclerotic myocardium was evaluated by measuring oxidative stress, apoptosis, infarct size, pathology, mitochondrial dysfunction and morphology of myocardium. The specific mechanism by which IPoC exerts cardioprotection in healthy and atherosclerotic myocardium was observed by measuring the expression of proteins involved in HIF-1, APMK and RISK pathways. The effect of HIF-1α overexpression on the cardioprotection by IPoC was observed by intravenous AAV9 -HIF-1α injection. ResultsIn healthy ischemic myocardium, IPoC exerted myocardial protective effects (antioxidant, anti-apoptosis, and improved mitochondrial function) through the activation of HIF-1, AMPK and RISK pathways. In atherosclerotic ischemic myocardium, IPoC exerted cardioprotection only through the activation of HIF-1 pathway; however, HIF-1 overexpression combined IPoC restored the activation of AMPK and RISK pathways, thereby further alleviating the myocardial IR injury. ConclusionsIn the atherosclerotic state, the HIF-1 pathway is the intrinsic mechanism by which IPoC exerts cardioprotective effects. The combination of HIF-1 upregulation and IPoC has a significant effect in reducing myocardial injury, which is worth being promoted and advocated. In addition, HIF-1-AMPK and HIF-1-RISK may be two endogenous cardioprotective signalling pathways with great value, which deserve to be thoroughly investigated in the future.

Cardioprotective Signaling Pathways in Obese Mice Submitted to Regular Exercise: Effect on Oxysterols.

Exercise induces cardioprotection against myocardial infarction, despite obesity, by restoring pro-survival pathways and increasing resistance of mitochondrial permeability transition pore (mPTP) opening at reperfusion. Among the mechanisms involved in the inactivation of these pathways, oxysterols appear interesting. Thus, we investigated the influence of regular exercise on the reperfusion injury salvage kinase (RISK) pathway, oxysterols, and mitochondria, in the absence of ischemia-reperfusion. We also studied 7β-hydroxycholesterol (7βOH) concentration (mass spectrometry) in human lean and obese subjects. Wild-type (WT) and obese (ob/ob) mice were assigned to sedentary conditions or regular treadmill exercise. Exercise significantly increased Akt phosphorylation, whereas 7βOH concentration was reduced. Moreover, exercise induced the translocation of PKCε from the cytosol to mitochondria. However, exercise did not affect the calcium concentration required to open mPTP in the mitochondria, neither in WT nor in ob/ob animals. Finally, human plasma 7βOH concentration was consistent with observations made in mice. In conclusion, regular exercise enhanced the RISK pathway by increasing kinase phosphorylation and PKCε translocation and decreasing 7βOH concentration. This activation needs the combination with stress conditions, i.e., ischemia-reperfusion, in order to inhibit mPTP opening at the onset of reperfusion. The human findings suggest 7βOH as a candidate marker for evaluating cardiovascular risk factors in obesity.

PM2.5 Exposure Lowers Mitochondrial Endurance During Cardiac Recovery in a Rat Model of Myocardial Infarction.

Many studies have reported the negative effect of PM2.5exposure on heart function which is likely to impair postcardiac surgery rehabilitation that is involved in recovery and wound healing, yet the direct effects ofPM2.5from diesel exhaust (DPM)on cardiac recovery is unknown.To study the impact ofDPM on cardiac recovery and repair, we utilized isoproterenol induced myocardial infarction (MI) model where female rats were exposed to DPM prior and after MI induction. The experimental groups comprise of normal, ISO control, DPM control (42days of exposure), DPM exposed prior (21days) and after (21days) MI induction (D + I + D) and DPM exposed (21days) after MI (I + D). Post-MI rat hearts from D + I + D group exhibited higher fibrosis, elevated cardiac injury and altered electrophysiology, where this pathology was also observed in I + D group animals which was mild.Loss of mitochondrial quality was evidentin DPM exposed animals with and without MI, where severe mitochondrial damage persisted in D + I + D group. In addition, these animals showed strikingdecline in ETC enzyme activity, ATP levels, mitochondrial copy number and down regulation of PGC1-α, TFAM and POLGalong with thegenes involved in mitophagy and mitofusion. Besides, the MI associated inactivation of cardio protective signalling pathways like PI3K and Akt were persistent in D + I + D group. In fact, I + D group animals also showed a similar pattern of change, but in a mild form. Taken together, exposure to PM2.5increases the risk, frequency or progression of MI by impairing the recovery potential of the myocardium.

Sex-related differences of early cardiac functional and proteomic alterations in a rat model of myocardial ischemia

BackgroundReduced cardiovascular risk in premenopausal women has been the focus of research in recent decades. Previous hypothesis-driven experiments have highlighted the role of sex hormones on distinct inflammatory responses, mitochondrial proteins, extracellular remodeling and estrogen-mediated cardioprotective signaling pathways related to post-ischemic recovery, which were associated with better cardiac functional outcomes in females. We aimed to investigate the early, sex-specific functional and proteomic changes following myocardial ischemia in an unbiased approach.MethodsIschemia was induced in male (M-Isch) and female (F-Isch) rats with sc. injection of isoproterenol (85 mg/kg) daily for 2 days, while controls (M-Co, F-Co) received sc. saline solution. At 48 h after the first injection pressure–volume analysis was carried out to assess left ventricular function. FFPE tissue slides were scanned and analyzed digitally, while myocardial proteins were quantified by liquid chromatography–tandem mass spectrometry (LC–MS/MS) using isobaric labeling. Concentrations of circulating steroid hormones were measured with LC–MS/MS. Feature selection (PLS and PLS-DA) was used to examine associations among functional, proteomic and hormonal datasets.ResultsInduction of ischemia resulted in 38% vs 17% mortality in M-Isch and F-Isch respectively. The extent of ischemic damage to surviving rats was comparable between the sexes. Systolic dysfunction was more pronounced in males, while females developed a more severe impairment of diastolic function. 2224 proteins were quantified, with 520 showing sex-specific differential regulation. Our analysis identified transcriptional, cytoskeletal, contractile, and mitochondrial proteins, molecular chaperones and the extracellular matrix as sources of disparity between the sexes. Bioinformatics highlighted possible associations of estrogens and their metabolites with early functional and proteomic alterations.ConclusionsOur study has highlighted sex-specific alterations in systolic and diastolic function shortly after ischemia, and provided a comprehensive look at the underlying proteomic changes and the influence of estrogens and their metabolites. According to our bioinformatic analysis, inflammatory, mitochondrial, chaperone, cytoskeletal, extracellular and matricellular proteins are major sources of intersex disparity, and may be promising targets for early sex-specific pharmacologic interventions.Graphical

Acute administration of the olive constituent, oleuropein, combined with post-conditioning mechanism exerts cardioprotective effects by modulating oxidative defense

Abstract Background/Introduction Oleuropein (oleu), the main polyphenolic constituent of olive, has cardioprotective effects against ischemia (I) – reperfusion (R) injury (IRI) when administered chronically. Purpose We aimed to assess the cardioprotection afforded by acute administration of oleu, to evaluate the underlying mechanism and whether it could enhance or imbed the cardioprotective manifestation of ischemic postconditioning (PostC). Methods Male rabbits were subjected to I/R (30/180 min) and randomized to 7 groups: (i) Control (ii) PostC: 8 cycles of 30-sec I/R at the onset of R; (iii) Oleu (100 mg/kg, iv bolus) at the 20th min of I; (iv) Oleu+NOS inhibitor (L-NAME, 10mg/kg); (v) Oleu+PI3K/Akt inhibitor (wortmannin, 60 μg/kg); (vi) Oleu+JAK2 inhibitor (AG490, 6μg/kg/min) and (vii) Oleu+PostC. Additionally, male C57BL6/J mice, subjected to I/R (30/180 min) and randomized to 4 groups: (i) Control; (ii) PostC: 3 cycles of 10-sec I/R at the onset of R; (iii) Oleu (350 mg/kg, iv bolus) at the 20th min of I; (iv) Oleu+PostC. In both animal models, infarct size (IS) expressed as percentage of infarct to area at risk ratio (I/R, %) was determined. Oleu's effect on cardiomyocytes was measured by MTT assay in adult rat cardiomyocytes exposed to simulated I (SI) and reoxygenation. We also assessed the effect of oleu on mitochondrial permeability transition pore (mPTP) through calcium retention capacity (CRC) assay and on cGMP accumulation in rat aortic smooth muscle cells. In a mouse model of IRI, we explored the effect of oleu on the recruitment of inflammatory monocytes and neutrophils in the IR heart using flow cytometry, whereas the effect of oleu on Nrf-2 signaling pathway-related genes was analyzed by western blot. Results In both animal models acute oleu administration reduced significantly the IS compared to the control group. None of the inhibitors of the classic cardioprotective pathways influence its IS limiting effects in rabbits. Combination of oleu with PostC caused further limitation of IS compared to PostC in both animal models (I/R Rabbits: 14.6±0.9 vs. 26.7±2.7%, p<0.01 and I/R mice: 11.5±1.8 vs. 20.3±1.8%, p<0.01). Oleu had a direct protective effect on cardiomyocytes since it significantly increased their viability following SI-reoxygenation injury as compared to non-treated cells. Oleu did not inhibit the calcium induced mPTP opening in isolated mitochondria and did not increase cGMP production. Oleu, PostC and their combination reduced inflammatory monocytes infiltration into the heart and the circulating monocytes. Oleu conferred additive cardioprotection on top of PostC, via increasing the expression of Nrf-2 and its downstream targets (HO-1 and SOD-2). Conclusion(s) Acute oleu administration combined with PostC provides robust and synergistic cardioprotection in experimental models of IRI by inducing antioxidant defense genes through Nrf-2 axis and independently of the classic cardioprotective signaling pathways. Funding Acknowledgement Type of funding sources: None.

Percutaneous Coronary Intervention (PCI) Reprograms Circulating Extracellular Vesicles from ACS Patients Impairing Their Cardio-Protective Properties.

Extracellular vesicles (EVs) are promising therapeutic tools in the treatment of cardiovascular disorders. We have recently shown that EVs from patients with Acute Coronary Syndrome (ACS) undergoing sham pre-conditioning, before percutaneous coronary intervention (PCI) were cardio-protective, while EVs from patients experiencing remote ischemic pre-conditioning (RIPC) failed to induce protection against ischemia/reperfusion Injury (IRI). No data on EVs from ACS patients recovered after PCI are currently available. Therefore, we herein investigated the cardio-protective properties of EVs, collected after PCI from the same patients. EVs recovered from 30 patients randomly assigned (1:1) to RIPC (EV-RIPC) or sham procedures (EV-naive) (NCT02195726) were characterized by TEM, FACS and Western blot analysis and evaluated for their mRNA content. The impact of EVs on hypoxia/reoxygenation damage and IRI, as well as the cardio-protective signaling pathways, were investigated in vitro (HMEC-1 + H9c2 co-culture) and ex vivo (isolated rat heart). Both EV-naive and EV-RIPC failed to drive cardio-protection both in vitro and ex vivo. Consistently, EV treatment failed to activate the canonical cardio-protective pathways. Specifically, PCI reduced the EV-naive Dusp6 mRNA content, found to be crucial for their cardio-protective action, and upregulated some stress- and cell-cycle-related genes in EV-RIPC. We provide the first evidence that in ACS patients, PCI reprograms the EV cargo, impairing EV-naive cardio-protective properties without improving EV-RIPC functional capability.

HIF‑1α in myocardial ischemia‑reperfusion injury (Review)

Myocardial ischemia-reperfusion injury (MIRI) is a severe injury to the ischemic myocardium following the recovery of blood flow. Currently, there is no effective treatment for MIRI in clinical practice. Over the past two decades, biological studies of hypoxia and hypoxia-inducible factor-1α (HIF-1α) have notably improved understanding of oxygen homeostasis. HIF-1α is an oxygen-sensitive transcription factor that mediates adaptive metabolic responses to hypoxia and serves a pivotal role in MIRI. In particular, previous studies have demonstrated that HIF-1α improves mitochondrial function, decreases cellular oxidative stress, activates cardioprotective signaling pathways and downstream protective genes and interacts with non-coding RNAs. The present review summarizes the roles and associated mechanisms of action of HIF-1α in MIRI. In addition, HIF-1α-associated MIRI intervention, including natural compounds, exosomes, ischemic preconditioning and ischemic post-processing are presented. The present review provides evidence for the roles of HIF-1α activation in MIRI and supports its use as a therapeutic target.

Acute administration of the olive constituent, oleuropein, combined with ischemic postconditioning increases myocardial protection by modulating oxidative defense

Oleuropein, one of the main polyphenolic constituents of olive, is cardioprotective against ischemia reperfusion injury (IRI). We aimed to assess the cardioprotection afforded by acute administration of oleuropein and to evaluate the underlying mechanism. Importantly, since antioxidant therapies have yielded inconclusive results in attenuating IRI-induced damage on top of conditioning strategies, we investigated whether oleuropein could enhance or imbed the cardioprotective manifestation of ischemic postconditioning (PostC). Oleuropein, given during ischemia as a single intravenous bolus dose reduced the infarct size compared to the control group both in rabbits and mice subjected to myocardial IRI. None of the inhibitors of the cardioprotective pathways, l-NAME, wortmannin and AG490, influence its infarct size limiting effects. Combined oleuropein and PostC cause further limitation of infarct size in comparison with PostC alone in both animal models. Oleuropein did not inhibit the calcium induced mitochondrial permeability transition pore opening in isolated mitochondria and did not increase cGMP production. To provide further insights to the different cardioprotective mechanism of oleuropein, we sought to characterize its anti-inflammatory potential in vivo. Oleuropein, PostC and their combination reduce inflammatory monocytes infiltration into the heart and the circulating monocyte cell population. Oleuropein's mechanism of action involves a direct protective effect on cardiomyocytes since it significantly increased their viability following simulated IRI as compared to non-treated cells. Οleuropein confers additive cardioprotection on top of PostC, via increasing the expression of the transcription factor Nrf-2 and its downstream targets in vivo. In conclusion, acute oleuropein administration during ischemia in combination with PostC provides robust and synergistic cardioprotection in experimental models of IRI by inducing antioxidant defense genes through Nrf-2 axis and independently of the classic cardioprotective signaling pathways (RISK, cGMP/PKG, SAFE).

Mitochondrion-targeting near-infrared fluorescent probe for detecting intracellular nanomolar level hydrogen sulfide with high recognition rate.

Hydrogen sulfide (H2S) typically plays biphasic biological roles in living organisms with subnormal H2S exerting cytoprotective effects such as participating in cardioprotective signaling pathways while H2S with higher-than-normal concentrations in localized tissues acting the opposite way such as inhibiting mitochondrial respiration. Such concentration-dependent biological and pathological roles of H2S with the wide involvement of mitochondria and the elusive feature of H2S definitely highlight the vital significance of fast and precise estimation of the physiological level of H2S in specific microenvironments, particularly within cellular mitochondria. In this work, we developed a new type of fluorescent probe (QcyCHO) featured with H2S-triggered off-to-on near-infrared (NIR) fluorescence conversion within ~ 10min, limit of detection (LOD) down to 8.3nM, and high recognition specificity over other similarly interfering species. The ideal mitochondrion-targeting ability, high recognition specificity over typical interfering substances and other physiologically relevant species, and the ability for mapping intracellular H2S in living cells of QcyCHO probe were also unequivocally confirmed, which imply its potential for shedding light on the biology of H2S and therapeutic development in H2S-associated diseases by identifying the specific physiological stimuli inducing H2S production and determining the levels of H2S at the location and time of stimulation.

Pre- and Post-Conditioning of the Heart: An Overview of Cardioprotective Signaling Pathways.

Since the discovery of ischemic pre- and post-conditioning, more than 30 years ago, the knowledge about the mechanisms and signaling pathways involved in these processes has significantly increased. In clinical practice, on the other hand, such advancement has yet to be seen. This article provides an overview of ischemic pre-, post-, remote, and pharmacological conditioning related to the heart. In addition, we reviewed the cardioprotective signaling pathways and therapeutic agents involved in the above-mentioned processes, aiming to provide a comprehensive evaluation of the advancements in the field. The advancements made over the last decades cannot be ignored and with the exponential growth in techniques and applications. The future of pre- and post-conditioning is promising.

Sarcolipin haploinsufficiency prevents dystrophic cardiomyopathy in mdx mice.

Sarcolipin (SLN) is an inhibitor of sarco/endoplasmic reticulum (SR) Ca2+-ATPase (SERCA) and expressed at high levels in the ventricles of animal models for and patients with Duchenne muscular dystrophy (DMD). The goal of this study was to determine whether the germline ablation of SLN expression improves cardiac SERCA function and intracellular Ca2+ (Ca2+i) handling and prevents cardiomyopathy in the mdx mouse model of DMD. Wild-type, mdx, SLN-haploinsufficient mdx (mdx:sln+/-), and SLN-deficient mdx (mdx:sln-/-) mice were used for this study. SERCA function and Ca2+i handling were determined by Ca2+ uptake assays and by measuring single-cell Ca2+ transients, respectively. Age-dependent disease progression was determined by histopathological examinations and by echocardiography in 6-, 12-, and 20-mo-old mice. Gene expression changes in the ventricles of mdx:sln+/- mice were determined by RNA-Seq analysis. SERCA function and Ca2+i cycling were improved in the ventricles of mdx:sln+/- mice. Fibrosis and necrosis were significantly decreased, and cardiac function was enhanced in the mdx:sln+/- mice until the study endpoint. The mdx:sln-/- mice also exhibited similar beneficial effects. RNA-Seq analysis identified distinct gene expression changes including the activation of the apelin pathway in the ventricles of mdx:sln+/- mice. Our findings suggest that reducing SLN expression is sufficient to improve cardiac SERCA function and Ca2+i cycling and prevent cardiomyopathy in mdx mice.NEW & NOTEWORTHY First, reducing sarcopolin (SLN) expression improves sarco/endoplasmic reticulum Ca2+ uptake and intracellular Ca2+ handling and prevents cardiomyopathy in mdx mice. Second, reducing SLN expression prevents diastolic dysfunction and improves cardiac contractility in mdx mice Third, reducing SLN expression activates apelin-mediated cardioprotective signaling pathways in mdx heart.

Novel Therapeutic Targets for Hypoxia-Related Cardiovascular Diseases: The Role of HIF-1.

Insufficient oxygen availability (hypoxia) is a precursor to numerous cardiovascular diseases, including atherosclerosis, pulmonary hypertension, and heart failure. The main site of hypoxic injury in the human body is the mitochondria, where oxygen acts as the final electron acceptor in the process of oxidative phosphorylation. Hypoxia-inducible factor (HIF) is activated in hypoxic conditions and acts as an important modulator of diverse target genes in the human body. The downstream genes of HIF include vital modulators of cardiovascular-related signaling pathways. Therefore, it is hypothesized that HIF represents a potential therapeutic target for the treatment and prevention of cardiovascular diseases. In this short review, we introduce the pathophysiology of hypoxic injury in cardiovascular disease, and we conclude from convincing evidence that HIF can modulate relevant cardioprotective signaling pathways.

Hidden cardiotoxicity of drugs ‐ paradigm change in cardiac safety testing in ischemic and comorbid conditions

Unexpected cardiac adverse events are one of the leading causes of interruption of clinical trials and drug withdrawals. It has been shown that cardiovascular risk factors and comorbidities (such as aging, metabolic diseases, etc) and their medications (e.g. nitrates, antidiabetic drugs, statins, etc) may interfere with cardiac ischemic tolerance and molecular signaling of endogenous cardioprotection. Indeed certain drugs may exert adverse events on the diseased heart that is hidden in the healthy myocardium. Hidden cardiotoxic effects of drugs may occur due to (i) enhancement of unwanted signaling due to ischemia/reperfusion injury and/or the presence of risk factors and/or (ii) inhibition of cardioprotective signaling pathways, both of which may lead to ischemia‐related cell death and pro‐arrhythmic events. This led to novel concept of “hidden cardiotoxicity”, i.e. cardiotoxicity seen only in the diseased heart, i.e. ischemia/reperfusion injury and/or its major comorbidities (Ferdinandy et al, Eur Heart J, 2019). Hidden cardiotoxicity cannot be revealed by the routinely used cardiac safety testing methods in “healthy” test systems, moreover, the mechanism of hidden cardiotoxocity is largely unknown. Therefore, here we summarize the current knowledge on hidden cardiotoxicity and urge the need for development of novel cardiac safety testing platforms for early detection of yet “hidden” cardiotoxicity. We also show an example of rofecoxib a COX2 inhibitor with hidden cardiotoxic properties.Support or Funding InformationThis study was supported by the National Research, Development and Innovation Office of Hungary (NKFIH; NVKP‐16‐1‐2016‐0017 National Heart Program). The research was also financed by the Higher Education Institutional Excellence Programme of the Ministry of Human Capacities in Hungary, within the framework of the Therapeutic development thematic programme of the Semmelweis University

Myocardial ischaemia reperfusion injury and cardioprotection in the presence of sensory neuropathy: Therapeutic options.

During the last decades, mortality from acute myocardial infarction has been dramatically reduced. However, the incidence of post‐infarction heart failure is still increasing. Cardioprotection by ischaemic conditioning had been discovered more than three decades ago. Its clinical translation, however, is still an unmet need. This is mainly due to the disrupted cardioprotective signalling pathways in the presence of different cardiovascular risk factors, co‐morbidities and the medication being taken. Sensory neuropathy is one of the co‐morbidities that has been shown to interfere with cardioprotection. In the present review, we summarize the diverse aetiology of sensory neuropathies and the mechanisms by which these neuropathies may interfere with ischaemic heart disease and cardioprotective signalling. Finally, we suggest future therapeutic options targeting both ischaemic heart and sensory neuropathy simultaneously.LINKED ARTICLESThis article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc

Dexmedetomidine Improves Cardiovascular and Ventilatory Outcomes in Critically Ill Patients: Basic and Clinical Approaches.

Dexmedetomidine (DEX) is a highly selective α2-adrenergic agonist with sedative and analgesic properties, with minimal respiratory effects. It is used as a sedative in the intensive care unit and the operating room. The opioid-sparing effect and the absence of respiratory effects make dexmedetomidine an attractive adjuvant drug for anesthesia in obese patients who are at an increased risk for postoperative respiratory complications. The pharmacodynamic effects on the cardiovascular system are known; however the mechanisms that induce cardioprotection are still under study. Regarding the pharmacokinetics properties, this drug is extensively metabolized in the liver by the uridine diphosphate glucuronosyltransferases. It has a relatively high hepatic extraction ratio, and therefore, its metabolism is dependent on liver blood flow. This review shows, from a basic clinical approach, the evidence supporting the use of dexmedetomidine in different settings, from its use in animal models of ischemia-reperfusion, and cardioprotective signaling pathways. In addition, pharmacokinetics and pharmacodynamics studies in obese subjects and the management of patients subjected to mechanical ventilation are described. Moreover, the clinical efficacy of delirium incidence in patients with indication of non-invasive ventilation is shown. Finally, the available evidence from DEX is described by a group of Chilean pharmacologists and clinicians who have worked for more than 10 years on DEX.

Hyperlipidaemia and cardioprotection: Animal models for translational studies.

Hyperlipidaemia is a well-established risk factor for cardiovascular diseases and therefore, many animal model have been developed to mimic the human abnormal elevation of blood lipid levels. In parallel, extensive research for the alleviation of ischaemia/reperfusion injury has revealed that hyperlipidaemia is a major co-morbidity that attenuates the cardioprotective effect of conditioning strategies (preconditioning, postconditioning and remote conditioning) and that of pharmacological interventions by interfering with cardioprotective signalling pathways. In the present review article, we summarize the existing data on animal models of hypercholesterolaemia (total, low density and HDL abnormalities) and hypertriglyceridaemia used in ischaemia/reperfusion injury and protection from it. We also provide recommendations on preclinical animal models to be used for translations of the cardioprotective strategies into clinical practice. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc.

Role of PI3K/Akt/Nrf2 signaling pathway in resveratrol preconditioning-induced cardioprotection in diabetic rats

Objective To evaluate the role of phosphatidylinositol-3-kinase/protein kinase B/nuclear factor erythroid 2-related factor 2 (PI3K/Akt/Nrf2) signaling pathway in resveratrol preconditioning-induced cardioprotection in diabetic rats. Methods Clean-grade healthy male Sprague-Dawley rats, aged 2-3 months, weighing 240-280 g, were used in the study.The diabetes model was established by intraperitoneal injection of streptozotocin 30 mg/kg once a day for 7 consecutive days.Forty diabetic rats were selected and divided into 4 groups (n=10 each) according to the random number table method: sham operation group (S group), myocardial ischemia-reperfusion (I/R) group (I/R group), resveratrol plus myocardial I/R group (Res+ I/R group), and PI3K inhibitor LY294002 plus resveratrol plus myocardial I/R group (LY+ Res+ I/R group). The myocardial I/R injury model was established by ligating the left anterior descending coronary artery for 30 min followed by 120-min reperfusion in anesthetized rats.Resveratrol 20 mg/kg was intraperitoneally injected once a day for 7 consecutive days at one week before surgery in Res+ I/R and LY+ Res+ I/R groups.LY294002 1.5 mg/kg was intraperitoneally injected at 30 min before operation in LY+ Res+ I/R group.After 120 min of reperfusion, blood samples were taken for determination of serum creatine kinase-MB (CK-MB) and lactic dehydrogenase (LDH) concentrations (by enzyme-linked immunosorbent assay), and myocardial tissues at the ischemic area were obtained for determination of superoxide dismutase (SOD), glutathione (GSH) and malondialdehyde (MDA)levels (by enzyme-linked immunosorbent assay) and expression of Akt, phosphorylated Akt (p-Akt), glycogen synthase kinase 3β (GSK3β), phosphorylated GSK3β (p-GSK3β) and Nrf2 (by Western blot). Results Compared with group S, serum CK-MB and LDH concentrations were significantly increased, the SOD and GSH levels were decreased, the MDA level was increased, and the expression of p-Akt and p-GSK3β was down-regulated in I/R group (P<0.05). Compared with I/R group, serum CK-MB and LDH concentrations were significantly decreased, the SOD and GSH levels were increased, the MDA level was decreased, and the expression of p-Akt, p-GSK3β and Nrf2 was up-regulated in Res+ I/R group (P<0.05). Compared with Res+ I/R group, serum CK-MB and LDH concentrations were significantly increased, the SOD and GSH levels were decreased, the MDA level was increased, and the expression of p-Akt, p-GSK3β and Nrf2 was down-regulated in LY+ Res+ I/R group (P<0.05). Conclusion The mechanism of resveratrol preconditioning-induced cardioprotection is related to activating PI3K/Akt/Nrf2 signaling pathway and inhibiting oxidative stress responses in diabetic rats. Key words: Myocardial reperfusion injury; Diabetes mellitus; Phenols; 1-phosphatidylinositol 3-kinase; Protein-serine-threonine kinases; NF-E2-related factor 2

Therapeutic contribution of melatonin to the treatment of septic cardiomyopathy: A novel mechanism linking Ripk3-modified mitochondrial performance and endoplasmic reticulum function

The basic pathophysiological mechanisms underlying septic cardiomyopathy have not yet been completely clarified. Disease-specific treatments are lacking, and care is still based on supportive modalities. The aim of our study was to assess the protective effects of melatonin on septic cardiomyopathy, with a focus on the interactions between receptor-interacting protein kinase 3 (Ripk3), the mitochondria, endoplasmic reticulum (ER) and cytoskeletal degradation in cardiomyocytes. Ripk3 expression was increased in heart samples challenged with LPS, followed by myocardial inflammation, cardiac dysfunction, myocardial breakdown and cardiomyocyte death. The melatonin treatment attenuated septic myocardial injury in a comparable manner to the genetic depletion of Ripk3. Molecular investigations revealed that Ripk3 intimately regulated mitochondrial function, ER stress, cytoskeletal homeostasis and cardioprotective signaling pathways. Melatonin-mediated inhibition of Ripk3 improved mitochondrial bioenergetics, reduced mitochondria-initiated oxidative damage, sustained mitochondrial dynamics, ameliorated ER stress, normalized calcium recycling, and activated cardioprotective signaling pathways (including AKT, ERK and AMPK) in cardiomyocytes. Interestingly, Ripk3 overexpression mediated resistance to melatonin therapy following the infection of LPS-treated hearts with an adenovirus expressing Ripk3. Altogether, our findings identify Ripk3 upregulation as a novel risk factor for the development of sepsis-related myocardial injury, and melatonin restores the physiological functions of the mitochondria, ER, contractile cytoskeleton and cardioprotective signaling pathways. Additionally, our data also reveal a new, potentially therapeutic mechanism by which melatonin protects the heart from sepsis-mediated dysfunction, possibly by targeting Ripk3.