Apoptosis in myocardial ischaemia and infarction

Gemfibrozil mitigates caspase-11-driven myocardial pyroptosis in ischemia/reperfusion injury in mice

The size of the infarct area following acute myocardial infarction (AMI) is a critical prognostic factor. Caspase-11-dependent pyroptosis has been implicated as a key mechanism driving cardiomyocyte death after AMI. However, no therapeutic agents have been developed to inhibit myocardial cell death by targeting caspase-11. This study investigates the effects of gemfibrozil, a potential caspase-11 inhibitor, on ischemia/reperfusion-induced myocardial pyroptosis in mice. To model AMI, the left coronary artery of C57BL/6 N mice was ligated for 1 h, followed by reperfusion. Levels of cleaved caspase-11 and the N-terminal fragment of gasdermin D (GSDMD-N) in ischemic myocardial tissue increased progressively over time after ischemia/reperfusion. Gemfibrozil treatment during reperfusion significantly attenuated these increases in cleaved caspase-11 and GSDMD-N levels. Moreover, gemfibrozil reduced the extent of myocardial infarct size during reperfusion. In cultured cardiomyocytes isolated from adult mice, hypoxia/reoxygenation-induced increases in caspase-11 and GSDMD cleavage were similarly mitigated by gemfibrozil, which concurrently prevented necrotic cell death. These findings demonstrate the involvement of caspase-11-dependent pyroptosis in myocardial cell death following ischemia/reperfusion and suggest that gemfibrozil holds promise as a therapeutic agent for reducing myocardial infarct size after AMI.

Necroptosis: a significant and promising target for intervention of cardiovascular disease

Due to changes in dietary structures, population aging, and the exacerbation of metabolic risk factors, the incidence of cardiovascular disease continues to rise annually, posing a significant health burden worldwide. Cell death plays a crucial role in the onset and progression of cardiovascular diseases. As a regulated endpoint encountered by cells under adverse stress conditions, the execution of necroptosis is regulated by classicalpathways, the calmodulin-dependent protein kinases (CaMK) pathway, and mitochondria-dependent pathways, and implicated in various cardiovascular diseases, including atherosclerosis, myocardial infarction, myocardial ischemia-reperfusion injury (IRI), heart failure, diabetic cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy, chemotherapy drug-induced cardiomyopathy, and abdominal aortic aneurysm (AAA). To further investigate potential therapeutic targets for cardiovascular diseases, we also analyzed the main molecules and their inhibitors involved in necroptosis in an effort to uncover insights for treatment.

Mitigation of Injury from Myocardial Infarction by Pentamidine, an Inhibitor of the Acetyltransferase Tip60

PURPOSE

There is an urgent unmet need for new pharmacologic approaches that promote re-muscularization and repair following myocardial infarction (MI). We previously reported that genetic depletion of the acetyltransferase Tip60 after MI in a mouse model activates the CM cell-cycle, reduces scarring, and restores cardiac function, and that these beneficial effects are mimicked by the Tip60-selective inhibitor TH1834. Here, we investigated whether the FDA-approved anti-microbial agent pentamidine, a Tip60 inhibitor from which TH1834 is derived, also protects from the damaging effects of MI.

METHODS

Adult (10-14 weeks old) C57Bl/6 mice were subjected to permanent left coronary artery ligation to induce MI. Subsequently, echocardiography, electrocardiography, cardiac staining, and molecular analyses were performed to monitor the effects of treatment with pentamidine on cardiac injury and function.

RESULTS

We report that transient systemic administration of pentamidine on days 3-16 post-MI at a daily dose of 3 mg/kg efficiently improved cardiac function for up to ten months. This was accompanied by improved survival, diminished scarring, and increased activation of cell-cycle markers in CMs located in the infarct border zone in the absence of hypertrophy. Histological assessments suggested that post-MI treatment with pentamidine reduced site-specific acetylation of the minor histone variant H2A.Z at lysines K4 and K7 in CMs, indicative of the dedifferentiation process which must occur prior to CM proliferation. Treating mice with pentamidine post-MI produced no prominent electrophysiological changes.

CONCLUSIONS

These findings support the translational potential of pentamidine for treatment of MI, and provide evidence that functional improvement is mediated, in part, by CM renewal due to inhibition of the acetyltransferase activity of Tip60.

Cardiomyocyte-restricted MIAT deletion is sufficient to protect against murine myocardial infarction

Myocardial infarction-associated transcript (MIAT), an intergenic long noncoding RNA (lncRNA), is conserved between rodents and humans and is directly linked to maladaptive cardiac remodeling in both patients and mouse models with various forms of heart failure (HF). We previously reported attenuation of cardiac stress, apoptosis, and fibrosis in a murine model of myocardial infarction (MI) with global MIAT ablation. Our transcriptomic profiling and mechanistic studies further revealed MIAT-induced activation of maladaptive genes, such as Hoxa4, Fmo2, Lrrn4, Marveld3, and Fat4. However, the source of MIAT and its contribution to MI and HF remain unknown. In this study, we generate a novel cardiomyocyte (CM)-specific MIAT conditional knockout mouse model, which exhibits improved cardiac function after MI. We further report that CM-specific MIAT ablation is sufficient to reduce cardiac damage, apoptosis, and fibrosis following chronic MI. Mechanistically, CM-specific MIAT deletion in mice leads to decreased expression of proapoptotic and pathological profibrotic genes, such as p53, Bak1, Col3a1, Col6a1, Postn, and Snail1 after chronic MI. These results enable us to begin to dissect cell-specific contributions to MIAT signaling and bolster the idea that MIAT plays a direct pathological role in CMs after MI.

Nitroxyl protects H9C2 cells from H/R-induced damage and inhibits autophagy via PI3K/Akt/mTOR pathway

BACKGROUND

Myocardial ischemia-reperfusion injury (MIRI) is an important complication in the treatment of heart failure, and its treatment has not made satisfactory progress. Nitroxyl (HNO) showed protective effects on the heart failure, however, the effect and underlying mechanism of HNO on MIRI remain largely unclear.

METHODS

MIRI model in this study was established to induce H9C2 cell injury through hypoxia/reoxygenation (H/R) in vitro. The cell viability was assessed by cell counting kit-8 assay. The effect of HNO on the apoptosis was detected by flow cytometry. DCFH-DA fluorescent probe method was applied to detect the level of intracellular reactive oxygen species (ROS). The morphology of mitochondria and autophagosomes were observed by transmission electron microscopy. Apoptosis, autophagy and PI3K/Akt/mTOR pathway-related proteins were detected by western blot.

RESULTS

The viability of H9C2 cells was significantly increased in the HNO group. HNO inhibited apoptosis and regulated expressions of key apoptotic protein, including Bax and Bcl-2. HNO reduced ROS levels and alleviated H/R-induced mitochondrial damage. HNO also inhibited autophagy and regulated expressions of key autophagy-related molecules, including LC3II, p62 and Beclin1. Further experiments demonstrated that the effects of HNO were mediated through upregulation of PI3K/Akt/mTOR pathway. Rapamycin reversed the inhibition of HNO on H/R-induced autophagy in H9C2 cells, which abrogated the protective effect of HNO.

CONCLUSION

This study provided the first evidence that HNO protected H/R-induced cardiomyocytes through inhibiting autophagy via the activation PI3K/Akt/mTOR pathway.

Galanin Reduces Myocardial Ischemia/Reperfusion Injury in Rats with Streptozotocin Diabetes

Most clinical studies confirm the negative impact diabetes mellitus (DM) has on the course and outcome of cardiovascular complications caused by a myocardial ischemia-reperfusion injury (IRI). In this regard, the search for new approaches to IRI treatment in diabetic myocardium is of undeniable value. The aim of this work was to study the effect of galanin (G) on the size of myocardial infarct (MI), on mitochondrial functions, and on the energy state in the area at risk (AAR) in rats with type 1 diabetes mellitus (DM1) subjected to regional myocardial ischemia and reperfusion. Rat G was obtained by solid-phase synthesis using the Fmoc strategy and purified by HPLC. DM1 was induced by streptozotocin administration. Myocardial IRI was modeled by occlusion of the left anterior descending coronary artery and subsequent reperfusion. G at a dose of 1 mg/kg was administered intravenously before reperfusion. G decreased MI size and plasma creatine kinase MB (CK-MB) activity in DM rats by 40 and 28%, respectively. G injection improved mitochondrial respiration in saponin-skinned fibers in the AAR: namely, the maximal ADP-stimulated state 3, respiratory control, and the functional relationship between the mitochondrial CK-MB and oxidative phosphorylation. G provided significantly higher ATP levels, total adenine nucleotide pool, and adenylate energy charge of cardiomyocytes. It also reduced total creatine loss in myocardial AAR in DM rats. The results suggest there is a possibility of therapeutic use of G in myocardial IRI complicated by DM1.

Columbianadin Ameliorates Myocardial Injury by Inhibiting Autophagy Through the PI3K/Akt/mTOR Signaling Pathway in AMI Mice and Hypoxic H9c2 Cells

Acute myocardial infarction (AMI) is a leading cause of mortality among cardiovascular diseases, yet effective therapies for AMI are limited. Previous studies have suggested cardioprotective effects of columbianadin (CBN), but its specific role in AMI and the underlying mechanisms remain unclear. This study aims to investigate whether CBN influences AMI and to elucidate the underlying mechanisms. We conducted a network pharmacology analysis to investigate the relationship between CBN and AMI. The AMI model was established by ligating the left anterior descending (LAD) artery in C57BL/6J mice, which were subsequently administered CBN. Hypoxic H9c2 cells were utilized to evaluate the effects of CBN in vitro. Our study revealed that CBN treatment significantly reduced myocardial infarction in AMI mice. It enhanced mitochondrial function and suppressed autophagy flux in hypoxic H9c2 cells. Furthermore, CBN downregulated the expression of LC3, Beclin1, and Atg 5 genes and proteins. In response to CBN treatment, the phosphorylation levels of PI3K, Akt, and mTOR increased. Notably, RAPA attenuated the protective effect of CBN in enhancing the survival of hypoxic H9c2 cells and abolished its regulation of autophagy-related proteins via the PI3K/Akt/mTOR signaling pathway. In conclusion, CBN reduces myocardial damage by suppressing autophagy via the PI3K/Akt/mTOR signaling pathway in AMI mice and hypoxic H9c2 cells.

Scp776, A Novel IGF-1 Fusion Protein for Acute Therapy to Promote Escape From Apoptosis in Tissues Affected by Ischemic Injury: 2 Randomized Placebo-Controlled Phase 1 Studies in Healthy Adults

Apoptosis is a major driver of cell loss and infarct expansion in ischemic injuries such as acute ischemic stroke (AIS) and acute myocardial infarction (AMI). Insulin-like growth factor-1 (IGF-1) can mitigate cell death and potentiate recovery following acute ischemic injury, but short half-life and nonspecificity limit its therapeutic potential. Scp776 is an IGF-1 fusion protein designed to target damaged tissue and promote apoptosis escape and is in clinical development as an acute therapy for AIS and AMI. Two phase 1 placebo-controlled studies in healthy volunteers evaluated safety, tolerability, pharmacokinetic profile, and pharmacodynamics under single (1, 2, or 4 mg/kg) or multiple (6, 6.2, or 7.25 mg/kg total doses) dosing regimens. In addition, a blood glucose management plan was developed and implemented to mitigate hypoglycemia that may develop following scp776 injection. Scp776 was well tolerated in healthy volunteers (n = 51) without serious adverse events. Exposure increased in a near dose-proportional manner with a mean half-life across all doses of 8 hours. Adaptive dextrose infusions maintained normal blood glucose levels with occasional mild hypoglycemic events. These results informed scp776 dose selection and the design of blood glucose monitoring protocols for phase 2 studies.

Distinct methylome profile of cfDNA in AMI patients reveals significant alteration in cAMP signaling pathway genes regulating cardiac muscle contraction

BACKGROUND

The role of epigenetics in cardiovascular diseases has paved the way for innovative therapeutic approaches. Investigating epigenetic changes using cell-free DNA (cfDNA) holds substantial promise beyond mere diagnostics, especially for heart-related conditions like acute myocardial infarction (AMI), where obtaining tissue samples is a challenge. This study explores the methylation patterns of cfDNA in AMI patients and compares them with genomic DNA (gDNA) from the same individuals, aiming to evaluate the effectiveness of cfDNA as a valuable resource for studying heart-related diseases.

METHODOLOGY

We generated global methylome profiles of cfDNA and gDNA from 25 AMI patients using EM-Seq. Tissue deconvolution analysis was performed to estimate tissue specificity based on the methylation patterns. Differentially methylated loci were identified and explored to understand AMI pathophysiology.

RESULTS

Comparative analysis of cfDNA and gDNA methylation patterns in AMI patients reveals cfDNA holds more significance than gDNA. Principal component analysis revealed distinct clusters for cfDNA and gDNA, indicating distinct methylome profiles. cfDNA originated from multiple sources, predominantly from neutrophils (~ 75%) and about 10% from the left atrium, highlighting cardiac-specific changes. In contrast, immune cells are the major source of gDNA, indicative of inflammatory responses. Gene set enrichment analysis (GSEA) associates cfDNA methylation patterns with pathways related to cardiac muscle contraction, inflammation, hypoxia, and lipid metabolism. The affected genes include G protein-coupled receptors (GHSR, FFAR2, HTR1A, and VIPR2) that are part of the cAMP signaling pathway.

CONCLUSION

Epigenetic changes in cfDNA are more specific to cardiac tissue compared to those in gDNA, providing better insights into the molecular mechanisms involved in AMI. Genes that are differentially methylated in cfDNA and regulate core pathways, such as cAMP signaling, could be targeted for clinical applications, including the development of effective biomarkers and therapeutic targets.

Global Research Trends on Exosome in Cardiovascular Diseases: A Bibliometric-Based Visual Analysis

Background

Exosomes in cardiovascular diseases (CVDs) have attracted huge attention with substantial value and potential. Our bibliometrics is based on literature from the field of cardiovascular exosomes over the past 30 years, which has been visualized to display the development process, research hotspots, and cutting-edge trends of clinical practices, mechanisms, and management strategies related to psych cardiology.

Methods

We selected articles and reviews on exosomes in CVDs from the core collection of Web of Science, and generated visual charts by using CiteSpace and VOSviewer software.

Results

Our research included 1613 publications. The number of exosome articles in CVD fluctuates slightly, but overall shows an increasing trend. The main research institutions were Tongji University and Nanjing Medical University. The International Journal of Molecular Sciences has the highest publication volume, while the Journal of Cellular and Molecular Medicine has the highest citation count. Among all the authors, Eduardo Marban ranks first in terms of publication volume and H-index. The most common keywords are exosome, extracellular vesicles, and angiogenesis.

Conclusion

This is a bibliometric study on the research hotspots and trends of exosomes in CVD. Exosome research in the field of cardiovascular medicine is on the rise. Some exosome treatment methods may become the focus of future research.

Chronic mitochondrial dynamic-targeted therapy alleviates left ventricular dysfunction by reducing multiple programmed cell death in post-myocardial infarction rats

Mitochondrial dysfunction and the activation of multiple programmed cell death (PCD) have been shown to aggravate the severity and mortality associated with the progression of myocardial infarction (MI). Although pharmacological modulation of mitochondrial dynamics, including treatment with the fusion promoter (M1) and the fission inhibitor (Mdivi-1), exerted cardioprotection against several cardiac complications, their roles in the post-MI model have never been investigated. Using a MI rat model instigated by permanent left-anterior descending (LAD) coronary artery occlusion, post-MI rats were randomly assigned to receive one of 4 treatments (n = 10/group): vehicle (DMSO 3%V/V), enalapril (10 mg/kg), Mdivi-1 (1.2 mg/kg) and M1 (2 mg/kg), while a control group of sham operated rats underwent surgery without LAD occlusion (n = 10). After 32-day treatment, cardiac and mitochondrial function, and histopathological morphology were investigated and molecular analysis was performed. Treatment with enalapril, Mdivi-1, and M1 significantly mitigated cardiac pathological remodeling, reduced myocardial injury, and improved left ventricular (LV) function in post-MI rats. Importantly, all interventions also attenuated mitochondrial dynamic imbalance and mitigated activation of apoptosis, necroptosis, and pyroptosis after MI. This investigation demonstrated for the first time that chronic mitochondrial dynamic-targeted therapy mitigated mitochondrial dysfunction and activation of PCD, leading to improved LV function in post-MI rats.

Pyroptosis and mitochondrial function participated in miR-654-3p-protected against myocardial infarction

Myocardial infarction (MI) is one of the leading causes of heart failure with highly complicated pathogeneses. miR-654-3p has been recognized as a pivotal regulator of controlling cell survival. However, the function of miR-654-3p in cardiomyocytes and MI has yet to be reported. This study aimed to identify the role of miR-654-3p in the regulation of myocardial infarction. To understand the contribution of miR-654-3p on heart function, we generated cardiac-specific knockdown and overexpression mice using AAV9 technology in MI injury. Mechanically, we combined cellular and molecular techniques, pharmaceutical treatment, RNA sequencing, and functional testing to elucidate the potential pathological mechanisms. We identified that mice subjected to MI decreased the expression of miR-654-3p in the border and infarcted area. Mice lacking miR-654-3p in the heart showed some inflammation infiltration and myocardial fibrosis, resulting in a mild cardiac injury. Furthermore, we found a deficiency of miR-654-3p in cardiomyocytes resulted in pyroptotic cell death but not other programmed cell death. Intriguingly, miR-654-3p deficiency aggravated MI-induced cardiac dysfunction, accompanied by higher myocardial fibrosis and cardiac enzymes and augmented pyroptosis activation. Cardiac elevating miR-654-3p prevented myocardial fibrosis and inflammation infiltration and decreased pyroptosis profile, thereby attenuating MI-induced cardiac damage. Using RNA sequence and molecular biological approaches, we found overexpression of miR-654-3p in the heart promoted the metabolic ability of the cardiomyocytes by promoting mitochondrial metabolism and mitochondrial respiration function. Our finding identified the character of miR-654-3p in protecting against MI damage by mediating pyroptosis and mitochondrial metabolism. These findings provide a new mechanism for miR-654-3p involvement in the pathogenesis of MI and reveal novel therapeutic targets. miR-654-3p expression was decreased after MI. Mice lacking miR-654-3p in the heart showed some inflammation infiltration and myocardial fibrosis, resulting in a mild cardiac injury. The deficiency of miR-654-3p in cardiomyocytes resulted in pyroptotic cell death. miR-654-3p deficiency aggravated MI-induced cardiac dysfunction, accompanied by higher myocardial fibrosis and cardiac enzymes and augmented pyroptosis activation. Overexpression of miR-654-3p prevented myocardial fibrosis and inflammation infiltration and decreased pyroptosis profile, thereby attenuating MI-induced cardiac damage. Overexpression of miR-654-3p in the heart promoted the metabolic ability of the cardiomyocytes by promoting mitochondrial metabolism and mitochondrial respiration function.

Rap1GAP exacerbates myocardial infarction by regulating the AMPK/SIRT1/NF-κB signaling pathway

Rap1 GTPase-activating protein (Rap1GAP) is an important tumor suppressor. The purpose of this study was to investigate the role of Rap1GAP in myocardial infarction (MI) and its potential mechanism. Left anterior descending coronary artery ligation was performed on cardiac-specific Rap1GAP conditional knockout (Rap1GAP-CKO) mice and control mice with MI. Seven days after MI, Rap1GAP expression in the hearts of control mice peaked, the expression of proapoptotic markers (Bax and cleaved caspase-3) increased, the expression of antiapoptotic factors (Bcl-2) decreased, and the expression of the inflammatory factors IL-6 and TNF-α increased; thus, apoptosis occurred, inflammation, infarct size, and left ventricular dysfunction increased, while the heart changes caused by MI were alleviated in Rap1GAP-CKO mice. Mouse heart tissue was obtained for transcriptome sequencing, and gene set enrichment analysis (GSEA) was used to analyze Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. We found that Rap1GAP was associated with the AMPK and NF-κB signaling pathways and that Rap1GAP inhibited AMPK/SIRT1 and activated the NF-κB signaling pathway in model animals. Similar results were observed in primary rat myocardial cells subjected to oxygen-glucose deprivation (OGD) to induce ischemia and hypoxia. Activating AMPK with the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) reversed the damage caused by Rap1GAP overexpression in cardiomyocytes. In addition, the coimmunoprecipitation results showed that exogenous Rap1GAP interacted with AMPK. Rap1GAP was verified to regulate the AMPK SIRT1/NF-κB signaling pathway and exacerbate the damage to myocardial cells caused by ischemia and hypoxia. In conclusion, our results suggest that Rap1GAP promotes MI by modulating the AMPK/SIRT1/NF-κB signaling pathway and that Rap1GAP may be a therapeutic target for MI treatment in the future.

The role of IFI16 in regulating PANoptosis and implication in heart diseases

Interferon Gamma Inducible Protein 16 (IFI16) belongs to the HIN-200 protein family and is pivotal in immunological responses. Serving as a DNA sensor, IFI16 identifies viral and aberrant DNA, triggering immune and inflammatory responses. It is implicated in diverse cellular death mechanisms, such as pyroptosis, apoptosis, and necroptosis. Notably, these processes are integral to the emergent concept of PANoptosis, which encompasses cellular demise and inflammatory pathways. Current research implies a significant regulatory role for IFI16 in PANoptosis, particularly regarding cardiac pathologies. This review delves into the complex interplay between IFI16 and PANoptosis in heart diseases, including atherosclerosis, myocardial infarction, heart failure, and diabetic cardiomyopathy. It synthesizes evidence of IFI16's impact on PANoptosis, with the intention of providing novel insights for therapeutic strategies targeting heart diseases.

Negative Impact of Acute Reloading after Mechanical Left Ventricular Unloading

Mechanical LV unloading for acute myocardial infarction (MI) is a promising supportive therapy to reperfusion. However, no data is available on exit strategy. We evaluated hemodynamic and cellular effects of reloading after Impella-mediated LV unloading in Yorkshire pigs. First, we conducted an acute study in normal heart to observe effects of unloading and reloading independent of MI-induced ischemic effects. We then completed an MI study to investigate optimal exit strategy on one-week infarct size, no-reflow area, and LV function with different reloading speeds. Initial studies showed that acute reloading causes an immediate rise in end-diastolic wall stress followed by a significant increase in cardiomyocyte apoptosis. The MI study did not result in any statistically significant findings; however, numerically smaller average infarct size and no-reflow area in the gradual reloading group prompt further examination of reloading approach as an important clinically relevant consideration.

Exploring Cutting-Edge Approaches to Potentiate Mesenchymal Stem Cell and Exosome Therapy for Myocardial Infarction

Cardiovascular diseases (CVDs) continue to be a significant global health concern. Many studies have reported promising outcomes from using MSCs and their secreted exosomes in managing various cardiovascular-related diseases like myocardial infarction (MI). MSCs and exosomes have demonstrated considerable potential in promoting regeneration and neovascularization, as well as exerting beneficial effects against apoptosis, remodeling, and inflammation in cases of myocardial infarction. Nonetheless, ensuring the durability and effectiveness of MSCs and exosomes following in vivo transplantation remains a significant concern. Recently, novel methods have emerged to improve their effectiveness and robustness, such as employing preconditioning statuses, modifying MSC and their exosomes, targeted drug delivery with exosomes, biomaterials, and combination therapy. Herein, we summarize the novel approaches that intensify the therapeutic application of MSC and their derived exosomes in treating MI.

Macrophage mediators and mechanisms in cardiovascular disease

Macrophages are major players in myocardial infarction (MI) and atherosclerosis, two major cardiovascular diseases (CVD). Atherosclerosis is caused by the buildup of cholesterol-rich lipoproteins in blood vessels, causing inflammation, vascular injury, and plaque formation. Plaque rupture or erosion can cause thrombus formation resulting in inadequate blood flow to the heart muscle and MI. Inflammation, particularly driven by macrophages, plays a central role in both atherosclerosis and MI. Recent integrative approaches of single-cell analysis-based classifications in both murine and human atherosclerosis as well as experimental MI showed overlap in origin, diversity, and function of macrophages in the aorta and the heart. We here discuss differences and communalities between macrophages in the heart and aorta at steady state and in atherosclerosis or upon MI. We focus on markers, mediators, and functional states of macrophage subpopulations. Recent trials testing anti-inflammatory agents show a major benefit in reducing the inflammatory burden of CVD patients, but highlight a necessity for a broader understanding of immune cell ontogeny and heterogeneity in CVD. The novel insights into macrophage biology in CVD represent exciting opportunities for the development of novel treatment strategies against CVD.

Evaluation of Tyrosine Kinase Inhibitors Loaded Injectable Hydrogels for Improving Connexin43 Gap Junction Intercellular Communication

Myocardial infarction (MI) is one of the leading causes of death in the developed world, and the loss of cardiomyocytes plays a critical role in the pathogenesis of heart failure. Implicated in this process is a decrease in gap junction intercellular communication due to remodeling of Connexin43 (Cx43). We previously identified that intraperitoneal injection of the Pyk2 inhibitor PF4618433 reduced infarct size, maintained Cx43 at the intercalated disc in left ventricle hypertrophic myocytes, and improved cardiac function in an MI animal model of heart failure. With the emergence of injectable hydrogels as a therapeutic toward the regeneration of cardiac tissue after MI, here, we provide proof of concept that the release of tyrosine kinase inhibitors from hydrogels could have beneficial effects on cardiomyocytes. We developed an injectable hydrogel consisting of thiolated hyaluronic acid and P123-maleimide micelles that can incorporate PF4618433 as well as the Src inhibitor Saracatinib and achieved sustained release (of note, Src activates Pyk2). Using neonatal rat ventricular myocytes in the presence of a phorbol ester, endothelin-1, or phenylephrine to stimulate cardiac hypertrophy, the release of PF4618433 from the hydrogel had the same ability to decrease Cx43 tyrosine phosphorylation and maintain Cx43 localization at the plasma membrane as when directly added to the growth media. Additional beneficial effects included decreases in apoptosis, the hypertrophic marker atrial natriuretic peptide (ANP), and serine kinases upregulated in hypertrophy. Finally, the presence of both PF4618433 and Saracatinib further decreased the level of ANP and apoptosis than each inhibitor alone, suggesting that a combinatorial approach may be most beneficial. These findings provide the groundwork to test if tyrosine kinase inhibitor release from hydrogels will have a beneficial effect in an animal model of MI-induced heart failure.

Mesenchymal stem cell-derived exosomes in myocardial infarction: Therapeutic potential and application

Myocardial infarction refers to the irreversible impairment of cardiac function resulting from the permanent loss of numerous cardiomyocytes and the formation of scar tissue. This condition is caused by acute and persistent inadequate blood supply to the heart's arteries. In the treatment of myocardial infarction, Mesenchymal stem cells (MSCs) play a crucial role because of their powerful therapeutic effects. These effects primarily stem from the paracrine secretion of multiple factors by MSCs, with exosome-carried microRNAs being the most effective component in promoting cardiac function recovery after infarction. Exosome therapy has emerged as a promising cell-free treatment for myocardial infarction as a result of its relatively simple composition, low immunogenicity and controlled transplantation dose. Despite these advantages, maintaining the stability of exosomes after transplantation and enhancing their targeting effect remain significant challenges in clinical applications. In recent developments, several approaches have been designed to optimize exosome therapy. These include enhancing exosome retention, improving their ability to target specific effects, pretreating MSC-derived exosomes and employing transgenic MSC-derived exosomes. This review primarily focuses on describing the biological characteristics of exosomes, their therapeutic potential and their application in treating myocardial infarction.

PANoptosis and cardiovascular disease: The preventive role of exercise training

Regulated cell death, including pyroptosis, apoptosis, and necroptosis, is vital for the body's defense system. Recent research suggests that these three types of cell death are interconnected, giving rise to a new concept called PANoptosis. PANoptosis has been linked to various diseases, making it crucial to comprehend its mechanism for effective treatments. PANoptosis is controlled by upstream receptors and molecular signals, which form polymeric complexes known as PANoptosomes. Cell death combines necroptosis, apoptosis, and pyroptosis and cannot be fully explained by any of these processes alone. Understanding pyroptosis, apoptosis, and necroptosis is essential for understanding PANoptosis. Physical exercise has been shown to suppress pyroptotic, apoptotic, and necroptotic signaling pathways by reducing inflammatory factors, proapoptotic factors, and necroptotic factors such as caspases and TNF-alpha. This ultimately leads to a decrease in cardiac structural remodeling. The beneficial effects of exercise on cardiovascular health may be attributed to its ability to inhibit these cell death pathways.

Exogenous GalR2-specific peptide agonist as a tool for treating myocardial ischemia/reperfusion injury

OBJECTIVES

The aim of this work was to elucidate the role of GalR2 receptor activation in protecting the rat heart in vivo from ischemia/reperfusion (I/R) damage by a pharmacological peptide agonist WTLNSAGYLLGPβAH-OH (G1) and full-length rat galanin GWTLNSAGYLLGPHAIDNHRSFSDKHGLT-NH2 (G2) using M871, a selective inhibitor of GalR2.

METHODS

The peptides were prepared by the automatic solid-phase synthesis using the Fmoc-strategy and purified by high-performance liquid chromatography (HPLC). A 40-min left anterior descending (LAD) coronary artery occlusion followed by a 60-min reperfusion was performed. The criteria for damage/protection of the heart were the infarct size (IS) and plasma activity of creatine kinase-MB (CK-MB) at the end of reperfusion.

RESULTS

Intravenous injection of G1 or G2 at an optimal dose of 1 mg/kg at the fifth minute of reperfusion significantly reduced the IS (by 35% and 32%, respectively) and activity of CK-MB at the end of reperfusion (by 43% and 38%, respectively) compared with the control. Administration of M871 (8 mg/kg) 5 min before the onset of reperfusion abolished the effects of G1 on IS and CK-MB activity, returning them to control values. Co-administration of M871 (8 mg/kg) with G2 attenuated protective effect of G2 on both IS and plasma СK-MB activity. However, differences in these parameters between the M871+G2 and G2 groups did not reach statistical significance (P = 0.139 and P = 0.121, respectively).

CONCLUSION

Thus, GalR2 is the principal receptor subtype that transduces the protective effects of galanin and ligand G1 in myocardial I/R injury. This suggests that GalR2-specific peptide agonists could be used as drug candidates for treating ischemic heart disease.

Combination human umbilical cord perivascular and endothelial colony forming cell therapy for ischemic cardiac injury

Cell-based therapeutics are promising interventions to repair ischemic cardiac tissue. However, no single cell type has yet been found to be both specialized and versatile enough to heal the heart. The synergistic effects of two regenerative cell types including endothelial colony forming cells (ECFC) and first-trimester human umbilical cord perivascular cells (FTM HUCPVC) with endothelial cell and pericyte properties respectively, on angiogenic and regenerative properties were tested in a rat model of myocardial infarction (MI), in vitro tube formation and Matrigel plug assay. The combination of FTM HUCPVCs and ECFCs synergistically reduced fibrosis and cardiomyocyte apoptosis, while promoting favorable cardiac remodeling and contractility. These effects were in part mediated by ANGPT2, PDGF-β, and VEGF-C. PDGF-β signaling-dependent synergistic effects on angiogenesis were also observed in vitro and in vivo. FTM HUCPVCs and ECFCs represent a cell combination therapy for promoting and sustaining vascularization following ischemic cardiac injury.

Being Eaten Alive: How Energy-Deprived Cells Are Disposed of, Mediated by C-Reactive Protein-Including a Treatment Option

In medicine, C-reactive protein (CRP) has become established primarily as a biomarker, predicting patient prognosis in many indications. Recently, however, there has been mounting evidence that it causes inflammatory injury. As early as 1999, CRP was shown to induce cell death after acute myocardial infarction (AMI) in rats and this was found to be dependent on complement. The pathological effect of CRP was subsequently confirmed in further animal species such as rabbit, mouse and pig. A conceptual gap was recently closed when it was demonstrated that ischemia in AMI or ischemia/hypoxia in the severe course of COVID-19 causes a drastic lack of energy in involved cells, resulting in an apoptotic presentation because these cells cannot repair/flip-flop altered lipids. The deprivation of energy leads to extensive expression on the cell membranes of the CRP ligand lysophosphatidylcholine. Upon attachment of CRP to this ligand, the classical complement pathway is triggered leading to the swift elimination of viable cells with the appearance of an apoptotic cell by phagocytes. They are being eaten alive. This, consequently, results in substantial fibrotic remodeling within the involved tissue. Inhibiting this pathomechanism via CRP-targeting therapy has been shown to be beneficial in different indications.

Promising remedies for cardiovascular disease: Natural polyphenol ellagic acid and its metabolite urolithins

BACKGROUND

Cardiovascular disease (CVD) is a significant worldwide factor contributing to human fatality and morbidity. With the increase of incidence rates, it is of concern that there is a lack of current therapeutic alternatives because of multiple side effects. Ellagic acid (EA), the natural polyphenol (C14H6O8), is abundant in pomegranates, berries, and nuts. EA and its intestinal microflora metabolite, urolithins, have recently attracted much attention as a potential novel "medicine" because of their wide pharmacological properties.

PURPOSE

This study aimed to critically analyze available literature to summarize the beneficial effects of EA and urolithins, and highlights their druggability and therapeutic potential in various CVDs.

METHODS

We systematically studied research and review articles between 1984 and 2022 available on various databases to obtain the data on EA and urolithins with no language restriction. Their cardiovascular protective activities, underlying mechanism, and druggability were highlighted and discussed comprehensively.

RESULTS

We found that EA and urolithins may exert preventive and curative effects on CVD with negligible side effects and possibly regulate lipid metabolism imbalance, pro-inflammatory factor production, vascular smooth muscle cell proliferation, cardiomyocyte apoptosis, endothelial cell dysfunction, and Ca2+ intake and release. Potentially, this may lead to the prevention and amelioration of atherosclerosis, hypertension, myocardial infarction, cardiac fibrosis, cardiomyopathy, cardiac arrhythmias, and cardiotoxicities in vivo. Several molecules and signaling pathways are associated with their therapeutic actions, including phosphatidylinositol 3-kinase/protein kinase B, mitogen-activated protein kinase, NF-κB, nuclear factor erythroid-2 related factor 2, sirtuin1, miRNA, and extracellular signal-regulated kinase 1/2.

CONCLUSION

In vitro and in vivo studies shows that EA and urolithins could be used as valid candidates for early prevention and effective therapeutic strategies for various CVDs.

Predicting thrombotic cardiovascular outcomes induced by waterpipe-associated chemicals using comparative toxicogenomic database: Genes, phenotypes, and pathways

Hookah, or waterpipe, is a tobacco smoking device that has gained popularity in the United States. A growing body of evidence demonstrates that waterpipe smoke (WPS) is associated with various adverse effects on human health, including infectious diseases, cancer, and cardiovascular diseases (CVDs), particularly thrombotic events. However, the molecular mechanisms through which WPS contributes to disease development remain unclear. In this study, we utilized an analytical approach based on the Comparative Toxicogenomics Database (CTD) to integrate chemical, gene, phenotype, and disease data to predict potential molecular mechanisms underlying the effects of WPS, based on its chemical and toxicant profile. Our analysis revealed that CVDs were among the top disease categories with regard to the number of curated interactions with WPS chemicals. We identified 5674 genes common between those modulated by WPS chemicals and traditional tobacco smoking. The CVDs with the most curated interactions with WPS chemicals were hypertension, atherosclerosis, and myocardial infarction, whereas "particulate matter", "heavy metals", and "nicotine" showed the highest number of curated interactions with CVDs. Our analysis predicted that the potential mechanisms underlying WPS-induced thrombotic diseases involve common phenotypes, such as inflammation, apoptosis, and cell proliferation, which are shared across all thrombotic diseases and the three aforementioned chemicals. In terms of enriched signaling pathways, we identified several, including chemokine and MAPK signaling, with particulate matter exhibiting the most statistically significant association with all 12 significant signaling pathways related to WPS chemicals. Collectively, our predictive comprehensive analysis provides evidence that WPS negatively impacts health and offers insights into the potential mechanisms through which it exerts these effects. This information should guide further research to explore and better understand the WPS and other tobacco product-related health consequences.

Myocardial ischemia-reperfusion injury; Molecular mechanisms and prevention

Cardiovascular diseases are one of the leading causes of mortality in developed countries. Among cardiovascular disorders, myocardial infarction remains a life-threatening problem predisposing to the development and progression of ischemic heart failure. Ischemia/reperfusion (I/R) injury is a critical cause of myocardial injury. In recent decades, many efforts have been made to find the molecular and cellular mechanisms underlying the development of myocardial I/R injury and post-ischemic remodeling. Some of these mechanisms are mitochondrial dysfunction, metabolic alterations, inflammation, high production of ROS, and autophagy deregulation. Despite continuous efforts, myocardial I/R injury remains a major challenge in medical treatments of thrombolytic therapy, heart disease, primary percutaneous coronary intervention, and coronary arterial bypass grafting. The development of effective therapeutic strategies to reduce or prevent myocardial I/R injury is of great clinical significance.

Bio-inspired nanoparticles mediated from plant extract biomolecules and their therapeutic application in cardiovascular diseases: A review

Nanoparticles (NPs) have gained recognition for diagnosis, drug delivery, and therapy in fatal diseases. This review focuses on the benefits of green synthesis of bioinspired NPs using various plant extract (containing various biomolecules such as sugars, proteins, and other phytochemical compounds) and their therapeutic application in cardiovascular diseases (CVDs). Multiple factors including inflammation, mitochondrial and cardiomyocyte mutations, endothelial cell apoptosis, and administration of non-cardiac drugs, can trigger the cause of cardiac disorders. Furthermore, the interruption of reactive oxygen species (ROS) synchronization from mitochondria causes oxidative stress in the cardiac system, leading to chronic diseases such as atherosclerosis and myocardial infarction. NPs can decrease the interaction with biomolecules and prevent the incitement of ROS. Understanding this mechanism can pave the way for using green synthesized elemental NPs to reduce the risk of CVD. This review delivers information on the different methods, classifications, mechanisms and benefits of using NPs, as well as the formation and progression of CVDs and their effects on the body.

Effects of Taraxerol on Oxidative and Inflammatory Mediators in Isoproterenol-Induced Cardiotoxicity in an Animal Model

Myocardial infarction (MI) continues to be an important issue in healthcare systems worldwide, leading to high rates of morbidity and mortality. Despite ongoing efforts towards the development of preventive measures and treatments, addressing the challenges posed by MI remains difficult both in developed and developing countries. However, researchers recently investigated the potential cardioprotective effects of taraxerol utilizing an isoproterenol (ISO)-induced cardiotoxicity model among Sprague Dawley rats. Specifically, subcutaneous tissue injections consisting of 5.25 mg/kg or 8.5 mg/kg ISO were administered over two consecutive days as stimuli to induce cardiac injury. To investigate the possibility of preventing damage caused by ISO-induced cardiotoxicity by taraxerol treatment, five groups were formed: a normal control group (1% Tween 80), an ISO control group, an amlodipine group administered 5 mg/kg/day, and various doses of taraxerol. The study results showed that treatment significantly reduced cardiac marker enzymes. Additionally, pretreatment with taraxerol increased myocardial activity in SOD and GPx, leading to significant reductions in serum CK-MB levels along with MDA, TNF-α, and IL-6. Further histopathological analysis supported these observations, as treated animals had less cellular infiltration compared to untreated ones. These multifaceted findings suggest that oral administration of taraxerol could potentially protect hearts from ISO-caused damage by increasing endogenous antioxidant concentrations while decreasing pro-inflammatory cytokines.

The alkaloids of Corydalis hendersonii Hemsl. contribute to the cardioprotective effect against ischemic injury in mice by attenuating cardiomyocyte apoptosis via p38 MAPK signaling pathway

BACKGROUND

There is a characteristic Tibetan folk medicine in China named Corydalis hendersonii Hemsl. (CH) has been used for treatment of cardiovascular related diseases, called "plethora" in Tibetan medicine. Previous studies demonstrated that ethanol extract of CH showed anti-acute myocardial infarction (AMI) effect through inhibiting fibrosis and inflammation. Rich alkaloids fraction (RAF) is isolated from CH, but whether RAF possessing an equivalent effect with the CH ethanol extract and by which mechanism it protects against AMI has not yet reported. The paper aimed to study the potential role of RAF on myocardial injured mice and its underlying mechanism.

MATERIALS AND METHODS

Liquid chromatography mass spectrometry-ion trap-time of flight (LCMS-IT-TOF) was used to analyze the chemical profile and isolate pure compounds. The ligation of left anterior descending (LAD) of coronary artery in mice was used to evaluate the in vivo anti-AMI effect, by dividing into eight groups: Sham, Model, Fosinopril (10 mg/kg, i.g.), total extract (TE, 400 mg/kg, i.g.), poor alkaloids fraction  (PAF, 300 mg/kg, i.g.), and RAF (25, 50, and 100 mg/kg, respectively, i.g.) groups. Echocardiography was used to evaluate mice heart function through the index of left ventricular end-systolic  diameter (LVEDs), left ventricular end-diastolic diameter (LVEDd), fractional shortening (FS) and ejection fraction (EF). We detected the lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) in the serum and the plasma level of angiotensin II (AngII). The apoptosis of mice myocardial tissue was verified by TUNEL assay. The expression of p38 mitogen-activated protein kinases (p38 MAPK), Bcl-2 and Bcl-2-associated X protein (Bax) were detected through immunofluorescence staining, qRT-PCR and western blot in mice heart tissue and H9c2 cells.

RESULTS

Echocardiography data indicated that the values of LVEDd and LVEDs were reduced and the values of FS and EF were improved by TE and RAF significantly. RAF also decreased the levels of LDH, CK-MB and AngII and significantly inhibited inflammatory cells in the marginal zone of myocardial infarction. The TUNEL assay results showed that RAF significantly attenuated cell apoptosis. Immunofluorescence and qRT-PCR assay showed that RAF inhibited p38 MAPK, Bax, and Bcl-2 proteins in mice myocardium. Western blot results validated that the expressions of key proteins were inhibited by RAF. Also, the apoptotic cells and apoptosis-related proteins were dramatically reduced by RAF in vivo and in vitro. Besides, RAF and PAF were analyzed by LCMS-IT-TOF to identify the main compounds and to demonstrate the difference between them. The results showed that a total of 14 alkaloids were identified, which indicated that the isoquinoline alkaloids were the main ingredients in RAF may contributing to the cardioprotective effect in mice.

CONCLUSIONS

RAF improves cardiac function by inhibiting apoptosis via p38 MAPK signaling pathway, and RAF contributes to the effect against myocardial ischemic injury of TE in mice, which provides a substantial reference for the clinical application against ischemia heart disease and quality control of CH.

Chronic Pharmacological Modulation of Mitochondrial Dynamics Alleviates Prediabetes-Induced Myocardial Ischemia-Reperfusion Injury by Preventing Mitochondrial Dysfunction and Programmed Apoptosis

PURPOSE

There is an increasing body of evidence to show that impairment in mitochondrial dynamics including excessive fission and insufficient fusion has been observed in the pre-diabetic condition. In pre-diabetic rats with cardiac ischemia-reperfusion (I/R) injury, acute treatment with a mitochondria fission inhibitor (Mdivi-1) and a fusion promoter (M1) showed cardioprotection. However, the potential preventive effects of chronic Mdivi-1 and M1 treatment in a pre-diabetic model of cardiac I/R have never been elucidated.

METHODS

Male Wistar rats (n = 40) were fed with a high-fat diet (HFD) for 12 weeks to induce prediabetes. Then, all pre-diabetic rats received the following treatments daily via intraperitoneal injection for 2 weeks: (1) HFDV (Vehicle, 0.1% DMSO); (2) HFMdivi1 (Mdivi-1 1.2 mg/kg); (3) HFM1 (M1 2 mg/kg); and (4) HFCom (Mdivi-1 + M1). At the end of treatment protocols, all rats underwent 30 min of coronary artery ligation followed by reperfusion for 120 min.

RESULTS

Chronic Mdivi-1, M1, and the combined treatment showed markedly improved cardiac mitochondrial function and dynamic control, leading to a decrease in cardiac arrhythmias, myocardial cell death, and infarct size (49%, 42%, and 51% reduction for HFMdivi1, HFM1, and HFCom, respectively vs HFDV). All of these treatments improved cardiac function following cardiac I/R injury in pre-diabetic rats.

CONCLUSION

Chronic inhibition of mitochondrial fission and promotion of fusion exerted cardioprevention in prediabetes with cardiac I/R injury through the relief of cardiac mitochondrial dysfunction and dynamic alterations, and reduction in myocardial infarction, thus improving cardiac function.

GSDMD-mediated pyroptosis dominantly promotes left ventricular remodeling and dysfunction in post-myocardial infarction: a comparison across modes of programmed cell death and mitochondrial involvement

BACKGROUND

Myocardial infarction (MI) has recently accounted for more than one-third of global mortality. Multiple molecular pathological pathways, such as oxidative stress, inflammation, and mitochondrial dysfunction, have been recognized as possible mechanisms in the development of MI. Furthermore, different phases of ischemic injury following the progression of MI were also associated with multiple types of programmed cell death (PCDs), including apoptosis, necroptosis, ferroptosis, and pyroptosis. However, it remains unknown whether which types of PCDs play the most dominant role in post-myocardial infarction (post-MI).

METHOD

In this study, we used a preclinical rat model of MI induced by permanent left anterior descending coronary artery (LAD) ligation (n = 6) or a sham operated rat model (n = 6). After a 5-week experiment, cardiac function and morphology, mitochondrial studies, and molecular signaling analysis of PCDs were determined.

RESULTS

Herein, we demonstrated that post-MI rats had considerably impaired cardiac geometry, increased oxidative stress, myocardial injuries, and subsequently contractile dysfunction. They also exhibited worsened cardiac mitochondrial function and dynamic imbalance. More importantly, we found that post-MI mediated abundant myocardial cell death through multiple PCDs, including apoptosis, necroptosis, and pyroptosis, but not ferroptosis.

CONCLUSION

In this study, we provide the first insights into the mechanism of PCDs by pyroptosis, which is leveraged as the most dominant mode of cell death after MI.

Therapeutic potential and molecular mechanisms of salidroside in ischemic diseases

Rhodiola is an ancient wild plant that grows in rock areas in high-altitude mountains with a widespread habitat in Asia, Europe, and America. From empirical belief to research studies, Rhodiola has undergone a long history of discovery, and has been used as traditional medicine in many countries and regions for treating high-altitude sickness, anoxia, resisting stress or fatigue, and for promoting longevity. Salidroside, a phenylpropanoid glycoside, is the main active component found in all species of Rhodiola. Salidroside could enhance cell survival and angiogenesis while suppressing oxidative stress and inflammation, and thereby has been considered a potential compound for treating ischemia and ischemic injury. In this article, we highlight the recent advances in salidroside in treating ischemic diseases, such as cerebral ischemia, ischemic heart disease, liver ischemia, ischemic acute kidney injury and lower limb ischemia. Furthermore, we also discuss the pharmacological functions and underlying molecular mechanisms. To our knowledge, this review is the first one that covers the protective effects of salidroside on different ischemia-related disease.

Bergapten mediated inflammatory and apoptosis through AMPK/eNOS/AKT signaling pathway of isoproterenol-induced myocardial infarction in Wistar rats

Bergapten (BeG) is explored for its anti-inflammatory and antioxidant properties. Myocardial infarction (MI) is reported to be one of the leading cardiovascular diseases characterized by mitochondrial dysfunction and apoptosis. The main purpose of this study is to assess the cardiopreventive effects of BeG (50 mg/kg) in isoproterenol (ISO)-induced MI in Wistar rats. The increased infarct size after ISO induction was reduced simultaneously on treatment with BeG. Similarly, augmented levels of cardiac biomarkers, namely cardiac troponin T, creatine kinase (CK), cardiac troponin I, and CK-MB were also suppressed by BeG. The increased rate of lipid hydroperoxides and thiobarbituric acid reactive substances owing to the oxidative stress caused by free radical generation in ISO-induced rats were also inhibited by BeG. Antioxidants reduce oxidative stress by scavenging free radicals. ISO induction reduces these antioxidant enzymes glutathione peroxidase, catalase, superoxide dismutase, and glutathione, and levels causing oxidative cardiac damage to the heart tissue. BeG supplementation improved these enzymes synthesis preventing potential damage to the myocardium. Inflammation caused by ISO pretreatment increased the secretion of proinflammatory cytokines in ISO-induced rats. Pretreatment with BeG suppressed these inflammatory cytokines to a normal level in ISO + BeG-treated rats. The histopathological examination of the morphological characteristics showed that the intensity of cardiac damage caused by ISO induction was less in BeG pretreated rats with less inflammatory cells and no necrosis. BeG also showed promising results in the molecular alteration of AMP-activated protein kinase/endothelial nitric oxide synthase/protein kinase B signaling molecules. These observations emphasize the cardioprotective effects of BeG and its potential use as a drug in the near future.

Macrophages trigger cardiomyocyte proliferation by increasing epicardial vegfaa expression during larval zebrafish heart regeneration

Cardiac injury leads to the loss of cardiomyocytes, which are rapidly replaced by the proliferation of the surviving cells in zebrafish, but not in mammals. In both the regenerative zebrafish and non-regenerative mammals, cardiac injury induces a sustained macrophage response. Macrophages are required for cardiomyocyte proliferation during zebrafish cardiac regeneration, but the mechanisms whereby macrophages facilitate this crucial process are fundamentally unknown. Using heartbeat-synchronized live imaging, RNA sequencing, and macrophage-null genotypes in the larval zebrafish cardiac injury model, we characterize macrophage function and reveal that these cells activate the epicardium, inducing cardiomyocyte proliferation. Mechanistically, macrophages are specifically recruited to the epicardial-myocardial niche, triggering the expansion of the epicardium, which upregulates vegfaa expression to induce cardiomyocyte proliferation. Our data suggest that epicardial Vegfaa augments a developmental cardiac growth pathway via increased endocardial notch signaling. The identification of this macrophage-dependent mechanism of cardiac regeneration highlights immunomodulation as a potential strategy for enhancing mammalian cardiac repair.

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Heart regeneration in larval zebrafish is characterized in detail

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Macrophage ablation blocks cardiomyocyte proliferation after cardiac injury

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Macrophages synapse with epicardial cells and promote their proliferation

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Epicardial Vegfaa drives cardiomyocyte proliferation during cardiac regeneration

CTRP12 alleviates cardiomyocyte ischemia‑reperfusion injury via regulation of KLF15

Myocardial ischemia-reperfusion (I/R) serves a crucial role in myocardial infarction. C1q/TNF-related protein 12 (CTRP12) is a secretory protein involved in metabolism. It has been reported that CTRP12 participates in the regulation of numerous cardiovascular diseases. However, its role in myocardial I/R injury remains unclear. In the present study, the left anterior descending coronary artery in mice was ligated to establish a mouse I/R model. A myocardial hypoxia-reoxygenation (H/R) cell model was also established. Cardiomyocyte injury was evaluated using hematoxylin and eosin staining, Cell Counting Kit-8 and a lactate dehydrogenase (LDH) kit. The expression levels of CTRP12 and Krueppel-like factor 15 (KLF15) in murine myocardial tissues and H9c2 cells were determined using reverse transcription-quantitative PCR and western blotting, as KLF15 was previously reported to protect against I/R-induced cardiomyocyte damage. Furthermore, inflammatory factors TNF-α, IL-1β and IL-6 were analyzed using ELISA while apoptosis was assessed using TUNEL assays and western blotting. Moreover, the activity of the CTRP12 promoter was determined using a dual-luciferase reporter assay. The results demonstrated that I/R surgery markedly exacerbated myocardial tissue damage, whereas H/R treatment significantly reduced cell viability and significantly increased LDH activity as well as the release of inflammatory factors and apoptosis. I/R and H/R induction significantly reduced the expression levels of CTRP12 and KLF15. CTRP12 overexpression significantly alleviated H/R-induced cell injury and significantly inhibited inflammation and apoptosis. Further analysis demonstrated that KLF15 could significantly promote the activity of the CTRP12 promoter. However, following CTRP12 knockdown, KLF15 overexpression exacerbated cell injury, inflammation and apoptosis. In conclusion, the present study demonstrated that CTRP12 may mitigate inflammation and apoptosis in H/R-induced cardiomyocytes, possibly via the regulation of KLF15, which provided a theoretical basis for the potential treatment of I/R-induced myocardial infarction.

[The anti-ischemic and antioxidant activity of the pharmacological agonist of galanin receptor GalR2 and carnosine in in vitro and in vivo model systems]

Antioxidant and anti-ischemic properties of the pharmacological agonist of galanin receptor GalR2 WTLNSAGYLLGPβAH (Gal) and its C-terminal fragment, dipeptide carnosine (βAH), were studied in the model of regional ischemia and reperfusion of the rat heart in vivo in the dose range of 0.5-5.0 mg/kg and Cu²⁺-induced free radical oxidation of low density lipoproteins (LDL) of human plasma in vitro for peptide concentrations of 0.01 mM and 0.1 mM. Gal was obtained by automatic solid phase synthesis using the Fmoc methodology; its structure was characterized by 1H-NMR spectroscopy and MALDI-TOF mass spectrometry. Intravenous administration of the optimal dose of Gal (1 mg/kg) to rats after ischemia was more effective than carnosine in reducing of the myocardial infarct size and the activity of creatine kinase-MB and lactate dehydrogenase in blood plasma at the end of reperfusion. It also improved the metabolic state of the reperfused myocardium and reduced the formation of peroxidation products during reperfusion. Gal reduced more effectively the formation of adducts of hydroxyl radicals in the interstitium of the area at risk (AAR) of the rat heart than carnosine. Carnosine at a dose of 1 mg/kg more effectively increased the activity of catalase and glutathione peroxidase in the AAR by the end of reperfusion compared to Gal. In a model of Cu²⁺-initiated oxidation of human plasma LDL 0.1 mM carnosine demonstrated a significantly more pronounced reduction in the formation of lipid radicals compared to Gal. The results show that Gal can be considered as a promising agent that reduces myocardial injury during reperfusion and oxidative stress.

Therapeutic hypothermia for acute myocardial infarction: a narrative review of evidence from animal and clinical studies

Myocardial infarction (MI) is the leading cause of death from coronary heart disease and requires immediate reperfusion therapy with thrombolysis, primary percutaneous coronary intervention, or coronary artery bypass grafting. However, myocardial reperfusion therapy is often accompanied by cardiac ischemia/reperfusion (I/R) injury, which leads to myocardial injury with detrimental consequences. The causes of I/R injury are unclear, but are multifactorial, including free radicals, reactive oxygen species, calcium overload, mitochondria dysfunction, inflammation, and neutrophil-mediated vascular injury. Mild hypothermia has been introduced as one of the potential inhibitors of myocardial I/R injury. Although animal studies have demonstrated that mild hypothermia significantly reduces or delays I/R myocardium damage, human trials have not shown clinical benefits in acute MI (AMI). In addition, the practice of hypothermia treatment is increasing in various fields such as surgical anesthesia and intensive care units. Adequate sedation for anesthetic procedures and protection from body shivering has become essential during therapeutic hypothermia. Therefore, anesthesiologists should be aware of the effects of therapeutic hypothermia on the metabolism of anesthetic drugs. In this paper, we review the existing data on the use of therapeutic hypothermia for AMI in animal models and human clinical trials to better understand the discrepancy between perceived benefits in preclinical animal models and the absence thereof in clinical trials thus far.

Insight into the Role of the PI3K/Akt Pathway in Ischemic Injury and Post-Infarct Left Ventricular Remodeling in Normal and Diabetic Heart

Despite the significant decline in mortality, cardiovascular diseases are still the leading cause of death worldwide. Among them, myocardial infarction (MI) seems to be the most important. A further decline in the death rate may be achieved by the introduction of molecularly targeted drugs. It seems that the components of the PI3K/Akt signaling pathway are good candidates for this. The PI3K/Akt pathway plays a key role in the regulation of the growth and survival of cells, such as cardiomyocytes. In addition, it has been shown that the activation of the PI3K/Akt pathway results in the alleviation of the negative post-infarct changes in the myocardium and is impaired in the state of diabetes. In this article, the role of this pathway was described in each step of ischemia and subsequent left ventricular remodeling. In addition, we point out the most promising substances which need more investigation before introduction into clinical practice. Moreover, we present the impact of diabetes and widely used cardiac and antidiabetic drugs on the PI3K/Akt pathway and discuss the molecular mechanism of its effects on myocardial ischemia and left ventricular remodeling.

Doxorubicin-induced apoptosis enhances monocyte infiltration and adverse cardiac remodeling in diabetic animals

Diabetic cancer patients were treated with doxorubicin (DOX), a potent chemotherapeutic drug that induces cardiac toxicity; however, molecular mechanisms of cardiac toxicity in this specific disease progression in patients and animal models are completely unknown. Therefore, we designed a study to understand the effects of DOX-induced cardiac toxicity in diabetic animals and the involved pathophysiological mechanisms. C57BL/6 J mice were divided into four DOX- and diabetic (streptozotocin; STZ) - treated groups; control, STZ, DOX, and DOX+STZ. At day 14, animals were sacrificed, echocardiography was used to examine heart function, and heart and blood samples were collected to investigate apoptotic mechanisms (caspase 3, BAX, B-Cell leukemia/lymphoma 2 (Bcl2)), inflammation, and cardiac remodeling. Our data shows a significant (p < 0.05) increase in glucose levels, apoptotic markers, and monocyte infiltration at the site of apoptosis and triggered inflammatory immune response (tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6)), in DOX+STZ animals compared with control and experimental groups. We also observed significant (p < 0.05) increase in myofibrillar area, fibrosis, and significantly decreased (p < 0.05) cardiac function in DOX-treated diabetic animals compared with controls. In conclusion, our data suggest that DOX induces significantly increased apoptosis, fibrosis, and structural alterations in diabetic hearts compared with non-diabetic animals.

Canagliflozin and Dapagliflozin Attenuate Glucolipotoxicity-Induced Oxidative Stress and Apoptosis in Cardiomyocytes via Inhibition of Sodium-Glucose Cotransporter-1

Sodium-dependent glucose cotransporter 2 inhibitors (SGLT2) are recently approved drugs for the treatment of diabetes that regulate blood glucose levels by inhibiting reabsorption of glucose and sodium in the proximal tubules of the kidney. SGLT2 inhibitors have also shown cardiovascular (CV) benefits in diabetic patients. However, the therapeutic efficacy of SGLT2 inhibitors with respect to CV disease needs further investigation. Thus, the aim of the present study was to examine the effects of SGLT2 inhibitors, canagliflozin (CANA) and dapagliflozin (DAPA) in vitro under glucolipotoxic condition by treating cultured cardiomyocytes (H9C2) with high glucose (HG) and high lipid, palmitic acid (PA), to investigate whether inhibition of sodium glucose cotransporter could prevent any harmful effects of glucolipotoxicity in these cells. SGLT1 expression was measured by immunofluorescence staining and quantitative polymerase chain reaction. Oxidative stress and apoptosis were measured by flow cytometry. Hypertrophy was measured by hematoxylin and eosin (H&E) and crystal violet staining. A significant increase in SGLT1 expression was observed in HG- and PA-treated cardiomyocytes. Also, a significant increase in reactive oxygen species generation and apoptosis was observed in HG+PA-treated cultured cardiomyocytes. HG- and PA-treated cardiomyocytes developed significant structural alterations. All these effects of HG and PA were attenuated by CANA and DAPA. In conclusion, our study demonstrates upregulation of SGLT1 induces oxidative stress and apoptosis in cultured cardiomyocytes. Thus, inhibition of SGLT1 may be used as a possible approach for the treatment of CVD in diabetic patients.

The impact of autophagy modulation on phenotype and survival of cardiac stromal cells under metabolic stress

Cardiac stromal cells (CSCs) embrace multiple phenotypes and are a contributory factor in tissue homeostasis and repair. They can be exploited as therapeutic mediators against cardiac fibrosis and remodeling, but their survival and cardioprotective properties can be decreased by microenvironmental cues. We evaluated the impact of autophagy modulation by different pharmacological/genetic approaches on the viability and phenotype of murine CSCs, which had been subjected to nutrient deprivation or hyperglycemia, in order to mimic relevant stress conditions and risk factors of cardiovascular diseases. Our results show that autophagy is activated in CSCs by nutrient deprivation, and that autophagy induction by trehalose or autophagy-related protein 7 (ATG7)-overexpression can significantly preserve CSC viability. Furthermore, autophagy induction is associated with a higher proportion of primitive, non-activated stem cell antigen 1 (Sca1)-positive cells, and with a reduced fibrotic fraction (positive for the discoidin domain-containing receptor 2, DDR2) in the CSC pool after nutrient deprivation. Hyperglycemia, on the other hand, is associated with reduced autophagic flux in CSCs, and with a significant reduction in primitive Sca1+ cells. Autophagy induction by adenoviral-mediated ATG7-overexpression maintains a cardioprotective, anti-inflammatory and pro-angiogenic paracrine profile of CSCs exposed to hyperglycemia for 1 week. Finally, autophagy induction by ATG7-overexpression during hyperglycemia can significantly preserve cell viability in CSCs, which were subsequently exposed to nutrient deprivation, reducing hyperglycemia-induced impairment of cell resistance to stress. In conclusion, our results show that autophagy stimulation preserves CSC viability and function in response to metabolic stressors, suggesting that it may boost the beneficial functions of CSCs in cardiac repair mechanisms.

Myocardial Protecting Role of Glutamine in Patients with Low Ejection Fraction Undergoing Elective On-Pump Coronary Artery Bypass Graft Surgery

Purpose

Myocardial injury due to on-pump coronary artery bypass grafting (CABG) in patients with low ejection fraction (EF) is associated with poor outcomes. This study determines whether intravenous glutamine could protect the myocardium during on-pump CABG in patients with low EF.

Materials and Methods

This was a double-blind, randomized controlled trial to assess glutamine as a myocardial protector during on-pump CABG in patients with left ventricle EF of 31–50%, conducted from January to October 2021. Patients in the glutamine group (n = 30) received 0.5 g/kg of 20% glutamine solution diluted with 0.9% NaCl up to 500 mL in total volume over a period of 24 hours. Patients in the control group (n = 30) received 0.9% NaCl over the same period. The primary outcomes were plasma troponin I and plasma glutamine levels. Secondary outcomes included α-ketoglutarate (α-KG) levels and histopathology scoring of the right atrial appendage tissue, plasma lactate levels, hemodynamic measurement, and morbidity.

Results

Twenty-nine patients from each group (58 in total) were included in the analysis. Plasma troponin I levels at 6 and 24 hours after cardiopulmonary bypass (CPB) were significantly lower in the glutamine than the control group (mean 3.43 ± 1.51 ng/mL vs mean 4.41 ± 1.89 ng/mL; p = 0.034; median 3.08 ng/mL [min–max: 1.30–6.59] vs median 3.77 ng/mL [min–max: 0.00–36.53]; p = 0.038, respectively). Plasma glutamine levels at 24 hours after CPB were significantly higher in the glutamine than the control group (mean 935.42 ± 319.10 μmol/L vs mean 634.79 ± 243.89 μmol/L, p = 0.001). Plasma lactate levels at 6 and 24 hours after CPB were significantly lower in the glutamine than the control group (median 5.30 mmol/L [min-max: 1.20–9.50] vs median 5.70 mmol/L [min-max: 2.80–11.30], p = 0.042; mean 2.08 ± 0.67 mmol/L vs mean 2.46 ± 0.69 mmol/L, p = 0.044, respectively). Myocardial injury score was significantly lower in the glutamine than the control group (mean 1.30 ± 0.24 vs mean 1.48 ± 0.26, p = 0.011).

Conclusion

Perioperative administration of 0.5 g/kg intravenous glutamine solution over the period of 24 hours has myocardial protection effect in patients with low EF who undergo elective on-pump CABG.

Therapeutic potentials of cell death inhibitors in rats with cardiac ischaemia/reperfusion injury

Growing evidence demonstrated that cell death pathways including ferroptosis, apoptosis and necroptosis contribute to cardiac ischaemia/reperfusion (I/R) injury. We hypothesized that ferroptosis, apoptosis and necroptosis contribute differently to myocardial damage during acute cardiac I/R injury. Rats underwent cardiac I/R or sham operation. I/R-operated rats were divided into 4 groups: vehicle, apoptosis (Z-vad), ferroptosis (Fer-1) and necroptosis (Nec-1) inhibition. Rats in each cell death inhibitor group were subdivided into 3 different dose regimens: low, medium and high. Infarct size, left ventricular (LV) function, arrhythmias and molecular mechanism were investigated. Cardiac I/R caused myocardial infarction, LV dysfunction, arrhythmias, mitochondrial dysfunction, mitochondrial dynamic imbalance, inflammation, apoptosis and ferroptosis. Infarct size, LV dysfunction, mitochondrial dysfunction, apoptosis and ferroptosis were all reduced to a similar extent in rats treated with Z-vad (low and medium doses) or Fer-1 (medium and high doses). Fer-1 treatment also reduced mitochondrial dynamic imbalance and inflammation. No evidence of necroptosis was found in association with acute I/R injury, therefore Nec-1 treatment could not be assessed. Apoptosis and ferroptosis, not necroptosis, contributed to myocardial damage in acute I/R injury. Inhibitors of these 2 pathways provided effective cardioprotection in rats with I/R injury though modulation of mitochondrial function and attenuated apoptosis and ferroptosis.

The Association between Hypoxia-Induced Low Activity and Apoptosis Strongly Resembles That between TTX-Induced Silencing and Apoptosis

In the penumbra of a brain infarct, neurons initially remain structurally intact, but perfusion is insufficient to maintain neuronal activity at physiological levels. Improving neuronal recovery in the penumbra has large potential to advance recovery of stroke patients, but penumbral pathology is incompletely understood, and treatments are scarce. We hypothesize that low activity in the penumbra is associated with apoptosis and thus contributes to irreversible neuronal damage. We explored the putative relationship between low neuronal activity and apoptosis in cultured neurons exposed to variable durations of hypoxia or TTX. We combined electrophysiology and live apoptosis staining in 42 cultures, and compared effects of hypoxia and TTX silencing in terms of network activity and apoptosis. Hypoxia rapidly reduced network activity, but cultures showed limited apoptosis during the first 12 h. After 24 h, widespread apoptosis had occurred. This was associated with full activity recovery observed upon reoxygenation within 12 h, but not after 24 h. Similarly, TTX exposure strongly reduced activity, with full recovery upon washout within 12 h, but not after 24 h. Mean temporal evolution of apoptosis in TTX-treated cultures was the same as in hypoxic cultures. These results suggest that prolonged low activity may be a common factor in the pathways towards apoptosis.

Validated Impacts of N6-Methyladenosine Methylated mRNAs on Apoptosis and Angiogenesis in Myocardial Infarction Based on MeRIP-Seq Analysis

Objectives: N6-methyladenosine (m⁶A) is hypothesized to play a role in the regulation of pathogenesis of myocardial infarction (MI). This study was designed to compare m⁶A-tagged transcript profiles to identify mRNA-specific changes on pathophysiological variations after MI.

Methods: N6-methyladenosine methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) were interacted to select m⁶A-modified mRNAs with samples collected from sham operated and MI rat models. m⁶A methylation regulated mRNAs were interacted with apoptosis/angiogenesis related genes in GeneCards. Afterwards, MeRIP-quantitative real-time PCR (MeRIP-qRT-PCR) was performed to measure m⁶A methylation level of hub mRNAs. m⁶A methylation variation was tested under different oxygen concentration or hypoxic duration in H9c2 cells and HUVECs. In addition, Western blot and qRT-PCR were employed to detect expression of hub mRNAs and relevant protein level. Flow cytometry and Tunel assay were conducted to assess apoptotic level. CCK-8, EdU, and tube formation assay were performed to measure cell proliferation and tube formation ability.

Results: Upregulation of Mettl3 was firstly observed in vivo and in vitro, followed by upregulation of m⁶A methylation level. A total of 567 significantly changed m⁶A methylation peaks were identified, including 276 upregulated and 291 downregulated peaks. A total of 576 mRNAs were upregulated and 78 were downregulated. According to combined analysis of MeRIP-seq and RNA-seq, we identified 26 significantly hypermethylated and downregulated mRNAs. Based on qRT-PCR and interactive analysis, Hadh, Kcnn1, and Tet1 were preliminarily identified as hub mRNAs associated with apoptosis/angiogenesis. MeRIP-qRT-PCR assay confirmed the results from MeRIP-seq. With the inhibition of Mettl3 in H9c2 cells and HUVECs, downregulated m⁶A methylation level of total RNA and upregulated expression of hub mRNAs were observed. Increased m⁶A level was verified in the gradient context in terms of prolonged hypoxic duration and decreased oxygen concentration. Under simulated hypoxia, roles of Kcnn1 and Tet1 in angiogenesis and Hadh, Tet1, and Kcnn1 in apoptosis were further confirmed with our validation experiments.

Conclusion: Roles of m⁶A-modified mRNA transcripts in the context of MI were preliminarily verified. In the context of m⁶A methylation, three hub mRNAs were validated to impact the process of apoptosis/angiogenesis. Our study provided theoretical basis and innovative targets for treatment of MI and paved the way for future investigations aiming at exploring upstream epigenetic mechanisms of pathogenesis after MI.