Role of Oxidative Stress in Cardiac Dysfunction and Subcellular Defects Due to Ischemia-Reperfusion Injury

Cardioprotective effects of S-equol, a soybean metabolite with estrogen activity, and role of the PI3K/Akt pathway in a male rat model of ischemic reperfusion

PURPOSE

S-equol, an isoflavone metabolite with high estrogenic activity, exhibits organ-protective effects via the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway. While estrogen has cardioprotective effects against ischemia-reperfusion injury, whether S-equol shares this capability remains uncertain. This study aimed to assess the cardioprotective effects of S-equol on stunned myocardium using an isolated rat heart model and investigate the involvement of PI3K/Akt signaling pathway.

METHODS

Male rat hearts were perfused using the Langendorff system and divided into four groups: 1) modified Krebs-Henseleit (KH) buffer containing 1 μmol/L S-equol (EQ); 2) KH buffer (Cont); 3) KH buffer supplemented with 1 μmol/L S-equol and 100 nmol/L wortmannin (a specific PI3K inhibitor) (EQW); or 4) KH buffer containing wortmannin (ContW). After stabilization, each group was perfused for 20 min before undergoing 7.5 min of no-flow ischemia, followed by 20 min reperfusion. The primary outcome was the maximum left ventricular derivative of pressure development (left ventricle [LV] dP/dt max)after 20 min of reperfusion. Myocardial Akt and glycogen synthase kinase-3 beta (GSK-3β) were assayed using western blotting.

RESULTS

LV dP/dt max was greater in the EQ group than that in the Cont group after 15 and 20 min of reperfusion; however, this effect was attenuated in the presence of PI3K inhibitors. S-equol treatment increased Akt and suppressed GSK-3β expression in the EQ group compared to that in the Cont group. However, these effects were not observed in the presence of wortmannin.

CONCLUSION

S-equol exerts a protective effect against myocardial ischemia-reperfusion injury, possibly by activating PI3K/Akt signaling.

Electron-donable heterojunctions with synergetic Ru-Cu pair sites for biocatalytic microenvironment modulations in inflammatory mandible defects

The clinical treatments of maxillofacial bone defects pose significant challenges due to complex microenvironments, including severe inflammation, high levels of reactive oxygen species (ROS), and potential bacterial infection. Herein, we propose the de novo design of an efficient, versatile, and precise electron-donable heterojunction with synergetic Ru-Cu pair sites (Ru-Cu/EDHJ) for superior biocatalytic regeneration of inflammatory mandible defects and pH-controlled antibacterial therapies. Our studies demonstrate that the unique structure of Ru-Cu/EDHJ enhances the electron density of Ru atoms and optimizes the binding strength of oxygen species, thus improving enzyme-like catalytic performance. Strikingly, this biocompatible Ru-Cu/EDHJ can efficiently switch between ROS scavenging in neutral media and ROS generation in acidic media, thus simultaneously exhibiting superior repair functions and bioadaptive antibacterial properties in treating mandible defects in male mice. We believe synthesizing such biocatalytic heterojunctions with exceptional enzyme-like capabilities will offer a promising pathway for engineering ROS biocatalytic materials to treat trauma, tumors, or infection-caused maxillofacial bone defects.

Combined diosmin and bisoprolol attenuate cobalt chloride-induced cardiotoxicity and endothelial dysfunction through modulating miR-143-3P/MAPK/MCP-1, ERK5/CXCR4, Orai-1/STIM-1 signaling pathways

Even while accelerated cardiomyocyte apoptosis is one of the primary causes of cardiac damage, the underlying mechanism is still mostly unknown. In addition to examining potential protective effects of bisoprolol and diosmin against CoCl2-induced cardiac injury, the goal of this study was to identify potential mechanisms regulating the hypoxic cardiac damage caused by cobalt chloride (CoCl2). For a period of 21 days except Cocl2 14 days from the first day of the experiment, rats were split into the following groups: Normal control group, rats received vehicle only (2 ml/kg/day, p.o.), (Cocl2, 150 mg/kg/day, p.o.), bisoprolol (25 mg/kg/day, p.o.); diosmin (100 mg/kg/day, p.o.) and bisoprolol + diosmin + Cocl2 groups. At the end of the experimental period, serum was taken for estimation of cardiac function, lipid profile, and pro/anti-inflammatory cytokines. Moreover, tissue samples were collected for evaluation of oxidative stress, endothelial dysfunction, α-SMA, PKC-α, MiR-143-3P, MAPK, ERK5, MCP-1, CXCR4, Orai-1, and STIM-1. Diosmin and bisoprolol, either alone or in combination, enhance heart function by reducing abnormalities in the electrocardiogram and the hypotension brought on by CoCl2. Additionally, they significantly ameliorate endothelial dysfunction by downregulating the cardiac expressions of α-SMA, PKC-α, MiR-143-3P, MAPK, ERK5, MCP-1, CXCR4, Orai-1, and STIM-1. Bisoprolol and diosmin produced modulatory activity against inflammatory state, redox balance, and atherogenic index concurrently. Together, diosmin and bisoprolol, either alone or in combination, significantly reduced all the cardiac alterations brought on by CoCl2. The capacity to obstruct hypoxia-induced α-SMA, PKC-α, MiR-143-3P/MAPK/MCP-1, MiR-143-3P/ERK5/CXCR4, Orai-1/STIM-1 signaling activation, as well as their anti-inflammatory, antioxidant, and anti-apoptotic properties, may be responsible for these cardio-protective results.

Melatonin as an adjunctive therapy in cardiovascular disease management

Melatonin, N-acetyl-5-methoxytryptamine, is a neuroendocrine hormone secreted by the pineal gland. This pleiotropic indoleamine possesses amphiphilic properties, allowing it to penetrate most biological barriers and exert its effects at the subcellular level. Importantly, melatonin also plays a crucial role in regulating the body's response to circadian rhythms, adapting to internal and external environmental cues. Melatonin functions as a powerful antioxidant and free radical scavenger, protecting cells from oxidative damage. Its diverse physiological roles include maintaining the functional integrity of endothelial cells, thereby preventing atherosclerosis, a major contributor to cardiovascular disease. Additionally, melatonin exhibits antioxidant and free radical scavenging properties, potentially improving metabolic disorders. These combined effects suggest a unique adjunctive therapeutic potential for melatonin in treating cardiovascular diseases. This review aims to explore the mechanisms by which melatonin interacts with the cardiovascular system and investigates its potential use as an adjunctive therapeutic agent in managing cardiovascular disease.

Superior Anti-arrhythmogenic Effect of Combined Conditioning with Nicotinamide Mononucleotide and Ubiquinol in Myocardial Ischemia/Reperfusion Injury in Aged Rats

Purpose

Lethal ventricular arrhythmias are a significant clinical concern following reperfusion therapies in elderly patients with myocardial infarction. The combination of multi-target therapies to achieve optimal anti-arrhythmogenesis and improve the chances of successful translation for patient benefit has prompted considerable interest. This study examined the anti-arrhythmic effect of nicotinamide mononucleotide (NMN)/ubiquinol combination treatment following myocardial ischemia/reperfusion (IR) injury in aged rats, with an emphasis on the role of oxidative stress and nitric oxide (NO).

Methods

Male Wistar rats (n=30, 22-24 months old, 400-450 g) were randomized into five groups with or without IR and/or NMN and ubiquinol, either alone or in combination. NMN (100 mg/kg/48 hours) was administered intraperitoneally for 28 days before IR, and ubiquinol (30 mg/kg) was injected intravenously at early reperfusion. Electrocardiographic signals were recorded during the ischemia and the first 30 minutes of reperfusion. Two hours after reperfusion, myocardial hemodynamic and LDH release were measured, and the left ventricle samples were obtained to evaluate oxidative stress markers and NO levels.

Results

NMN/ubiquinol combination treatment significantly minimized the occurrence and severity of IR-induced arrhythmias, improved myocardial function, and reduced LDH release (P<0.05). It also decreased MDA content, increased superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) activities, and enhanced NO formation (P<0.05). This combined treatment showed greater efficacy than the single treatments.

Conclusion

This study revealed the anti-arrhythmic effect of NMN/ubiquinol combination treatment in IR-treated aged rats, which may be associated with reduced oxidative stress and increased NO formation. This combinational approach deserves more investigation due to its potential to confer better anti-arrhythmic effect during aging.

Management of ROS and Regulatory Cell Death in Myocardial Ischemia-Reperfusion Injury

Myocardial ischemia-reperfusion injury (MIRI) is fatal to patients, leading to cardiomyocyte death and myocardial remodeling. Reactive oxygen species (ROS) and oxidative stress play important roles in MIRI. There is a complex crosstalk between ROS and regulatory cell deaths (RCD) in cardiomyocytes, such as apoptosis, pyroptosis, autophagy, and ferroptosis. ROS is a double-edged sword. A reasonable level of ROS maintains the normal physiological activity of myocardial cells. However, during myocardial ischemia-reperfusion, excessive ROS generation accelerates myocardial damage through a variety of biological pathways. ROS regulates cardiomyocyte RCD through various molecular mechanisms. Targeting the removal of excess ROS has been considered an effective way to reverse myocardial damage. Many studies have applied antioxidant drugs or new advanced materials to reduce ROS levels to alleviate MIRI. Although the road from laboratory to clinic has been difficult, many scholars still persevere. This article reviews the molecular mechanisms of ROS inhibition to regulate cardiomyocyte RCD, with a view to providing new insights into prevention and treatment strategies for MIRI.

Reperfusion Injury in Patients With Acute Myocardial Infarction: JACC Scientific Statement

Despite impressive improvements in the care of patients with ST-segment elevation myocardial infarction, mortality remains high. Reperfusion is necessary for myocardial salvage, but the abrupt return of flow sets off a cascade of injurious processes that can lead to further necrosis. This has been termed myocardial ischemia-reperfusion injury and is the subject of this review. The pathologic and molecular bases for myocardial ischemia-reperfusion injury are increasingly understood and include injury from reactive oxygen species, inflammation, calcium overload, endothelial dysfunction, and impaired microvascular flow. A variety of pharmacologic strategies have been developed that have worked well in preclinical models and some have shown promise in the clinical setting. In addition, there are newer mechanical approaches including mechanical unloading of the heart prior to reperfusion that are in current clinical trials.

L-theanine abates oxidative stress and mitochondrial dysfunction in myocardial ischemia-reperfusion injury by positively regulating the antioxidant response

L-theanine (L-THE), a non-protein amino acid isolated from Camelia sinensis, has antioxidant properties that could prevent oxidative damage and mitochondrial dysfunction generated by myocardial ischemia and reperfusion (I/R) injury. The present study aimed to identify the effects of pretreatment with L-THE in rat hearts undergoing I/R. Wistar rats received vehicle or 250 mg/Kg L-THE intragastrically for 10 days. On day 11, hearts were removed under anesthesia and exposed to I/R injury in the Langendorff system. Measurement of left ventricular developed pressure and heart rate ex vivo demonstrates that L-THE prevents I/R-induced loss of cardiac function. Consequently, the infarct size of hearts subjected to I/R was significantly decreased when L-THE was administered. L-THE also mitigated I/R-induced oxidative injury in cardiac tissue by decreasing reactive oxygen species and malondialdehyde levels, while increasing the activity of antioxidant enzymes, SOD and CAT. Additionally, L-THE prevents oxidative phosphorylation breakdown and loss of inner mitochondrial membrane potential caused by I/R, restoring oxygen consumption levels, increasing respiratory control and phosphorylation efficiency, as well as buffering calcium overload. Finally, L-THE modifies the expression of genes involved in the antioxidant response through the overexpression of SOD1, SOD2 and CAT; as well as the transcriptional factors PPARα and Nrf2 in hearts undergoing I/R. In conclusion, L-THE confers cardioprotection against I/R injury by preventing oxidative stress, protecting mitochondrial function, and promoting overexpression of antioxidant genes. More studies are needed to place L-THE at the forefront of cardiovascular research and recommend its therapeutic use.

Effect of GLP-1 Receptor Agonist on Ischemia Reperfusion Injury in Rats with Metabolic Syndrome

Metabolic syndrome (MetS) represents an important factor that increases the risk of myocardial infarction, and more severe complications. Glucagon Like Peptide-1 Receptor Agonists (GLP-1RAs) exhibit cardioprotective potential, but their efficacy in MetS-related myocardial dysfunction has not been fully explored. Therefore, we aimed to assess the effects of exenatide and dulaglutide on heart function and redox balance in MetS-induced rats. Twenty-four Wistar albino rats with induced MetS were divided into three groups: MetS, exenatide-treated (5 µg/kg), dulaglutide-treated (0.6 mg/kg). After 6 weeks of treatment, in vivo heart function was assessed via echocardiography, while ex vivo function was evaluated using a Langendorff apparatus to simulate ischemia-reperfusion injury. Heart tissue samples were analyzed histologically, and oxidative stress biomarkers were measured spectrophotometrically from the coronary venous effluent. Both exenatide and dulaglutide significantly improved the ejection fraction by 3% and 7%, respectively, compared to the MetS group. Histological analyses corroborated these findings, revealing a reduction in the cross-sectional area of cardiomyocytes by 11% in the exenatide and 18% in the dulaglutide group, indicating reduced myocardial damage in GLP-1RA-treated rats. Our findings suggest strong cardioprotective potential of GLP-1RAs in MetS, with dulaglutide showing a slight advantage. Thus, both exenatide and dulaglutide are potentially promising targets for cardioprotection and reducing mortality in MetS patients.

CircBCL2L13 attenuates cardiomyocyte oxidative stress and apoptosis in cardiac ischemia‒reperfusion injury via miR-1246/PEG3 signaling

Ischemia‒reperfusion (I/R) is a common complication in the clinical treatment of acute myocardial infarction (MI), in which cardiomyocytes play a pivotal role in the recovery of cardiac function after reperfusion injury. The expression of numerous circular ribonucleic acids (circRNAs) is disrupted in I/R-induced cardiac damage, but the potential role of circRNAs in I/R damage has not been fully elucidated. The purpose of the present study was to clarify the biological action and molecular mechanism of circRNA 002166 (also termed circCL2L13) in postmyocardial I/R. Oxygen-glucose deprivation/reoxygenation (OGD/R) in an in vivo model was performed to simulate I/R damage. real-time polymerase chain reaction analysis was also conducted to evaluate the relationships of the SOD1, SOD2, NRF2, HO1 and GPX4 indicators with oxidative stress injury. TUNEL immunofluorescence was used to evaluate the degree of cardiomyocyte apoptosis in the different treatment groups. The circBCL2L13 level was markedly upregulated in myocardial tissues from a mouse I/R model. Overexpression of circBCL2L13 markedly attenuated the expression of oxidative stress-related genes and apoptosis in OGD/R-induced cardiomyocytes. A mechanistic study revealed that circBCL2L13 functions as a ceRNA for miR-1246 and modulates paternally expressed gene 3 (PEG3). Eventually, circBCL2L13 was proven to regulate PEG3 by targeting miR-1246, thereby protecting against OGD/R-induced cardiomyocyte oxidative damage and apoptosis. In conclusion, our study confirmed that the circBCL2L13/miR-1246/PEG3 axis suppressed the progression of OGD/R injury in cardiomyocytes, which might lead to new therapeutic strategies for cardiac I/R injury.

STUB1 is acetylated by KAT5 and alleviates myocardial ischemia-reperfusion injury through LATS2-YAP-β-catenin axis

Myocardial ischemia-reperfusion injury (MIRI) is involved in the pathogenesis of multiple cardiovascular diseases. This study elucidated the biological function of lysine acetyltransferase 5 (KAT5) in cardiomyocyte pyroptosis during MIRI. Oxygen-glucose deprivation/reoxygenation and left anterior descending coronary artery ligation were used to establish MIRI models. Here we show, KAT5 and STIP1 homology and U-box-containing protein 1 (STUB1) were downregulated, while large tumor suppressor kinase 2 (LATS2) was upregulated in MIRI models. KAT5/STUB1 overexpression or LATS2 silencing repressed cardiomyocyte pyroptosis. Mechanistically, KAT5 promoted STUB1 transcription via acetylation modulation, and subsequently caused ubiquitination and degradation of LATS2, which activated YAP/β-catenin pathway. Notably, the inhibitory effect of STUB1 overexpression on cardiomyocyte pyroptosis was abolished by LATS2 overexpression or KAT5 depletion. Our findings suggest that KAT5 overexpression inhibits NLRP3-mediated cardiomyocyte pyroptosis to relieve MIRI through modulation of STUB1/LATS2/YAP/β-catenin axis, providing a potential therapeutic target for MIRI.

The two different profiles in heart failure with preserved ejection fraction and type 2 diabetes mellitus: ischemic and diabetic

OBJECTIVE

Two profiles of patients with heart failure with preserved ejection fraction (HFpEF) and type 2 diabetes mellitus (T2DM) can be discerned: those with ischemic and those with diabetic cardiomyopathy (DMC). We aim to analyze clinical differences and prognosis between patients of these two profiles.

MATERIAL AND METHODS

This cohort study analyzes data from the Spanish Heart Failure Registry, a multicenter, prospective registry that enrolled patients admitted for decompensated heart failure and followed them for one year. Three groups were created according to the presence of T2DM and heart disease depending on the etiology (ischemic when coronary artery disease was present, or DMC when no coronary, valvular, or congenital heart disease; no hypertension; nor infiltrative cardiovascular disease observed on an endomyocardial biopsy). The groups and outcomes were compared.

RESULTS

A total of 466 patients were analyzed. Group 1 (n = 210) included patients with ischemic etiology and T2DM. Group 2 (n = 112) included patients with DMC etiology and T2DM. Group 3 (n = 144), a control group, included patients with ischemic etiology and without T2DM. Group 1 had more hypertension and dyslipidemia; group 2 had more atrial fibrillation (AF) and higher body mass index; group 3 had more chronic kidney disease and were older. In the regression analysis, group 3 had a better prognosis than group 1 (reference group) for cardiovascular mortality and HF readmissions (HR 0.44;95%CI 0.2-1; p = .049).

CONCLUSIONS

Patients with T2DM and HFpEF, who had the poorest prognosis, were of two different profiles: either ischemic or DMC etiology. The first had a higher burden of cardiovascular disease and inflammation whereas the second had a higher prevalence of obesity and AF. The first had a slightly poorer prognosis than the second, though this finding was not significant.

Protective effects of Pt-N-C single-atom nanozymes against myocardial ischemia-reperfusion injury

Effective therapeutic strategies for myocardial ischemia/reperfusion (I/R) injury remain elusive. Targeting reactive oxygen species (ROS) provides a practical approach to mitigate myocardial damage following reperfusion. In this study, we synthesize an antioxidant nanozyme, equipped with a single-Platinum (Pt)-atom (PtsaN-C), for protecting against I/R injury. PtsaN-C exhibits multiple enzyme-mimicking activities for ROS scavenging with high efficiency and stability. Mechanistic studies demonstrate that the excellent ROS-elimination performance of the single Pt atom center precedes that of the Pt cluster center, owing to its better synergistic effect and metallic electronic property. Systematic in vitro and in vivo studies confirm that PtsaN-C efficiently counteracts ROS, restores cellular homeostasis and prevents apoptotic progression after I/R injury. PtsaN-C also demonstrates good biocompatibility, making it a promising candidate for clinical applications. Our study expands the scope of single-atom nanozyme in combating ROS-induced damage and offers a promising therapeutic avenue for the treatment of I/R injury.

Myocardial ischemia/reperfusion: Translational pathophysiology of ischemic heart disease

Ischemic heart disease is the greatest health burden and most frequent cause of death worldwide. Myocardial ischemia/reperfusion is the pathophysiological substrate of ischemic heart disease. Improvements in prevention and treatment of ischemic heart disease have reduced mortality in developed countries over the last decades, but further progress is now stagnant, and morbidity and mortality from ischemic heart disease in developing countries are increasing. Significant problems remain to be resolved and require a better pathophysiological understanding. The present review attempts to briefly summarize the state of the art in myocardial ischemia/reperfusion research, with a view on both its coronary vascular and myocardial aspects, and to define the cutting edges where further mechanistic knowledge is needed to facilitate translation to clinical practice.

Anti-smoking drugs cytisine and varenicline reduce cardiac reperfusion injury in rat model of myocardial ischemia

Evidence to date indicates that activation of nicotinic acetylcholine receptors (nAChRs) can reduce cardiac injury from ischemia and subsequent reperfusion. The use of nAChR agonists in various animal models leads to a reduction in reperfusion injury. Earlier this effect was shown for the agonists of α7 nAChR subtype. In this work, we demonstrated the expression of mRNA encoding α4, α6 and β2 nAChR subunits in the left ventricle of rat heart. In a rat model of myocardial ischemia, we studied the effect of α4β2 nAChR agonists cytisine and varenicline, medicines used for the treatment of nicotine addiction, and found them to significantly reduce myocardium ischemia-reperfusion injury, varenicline manifesting a higher protection. Dihydro-β-erythroidine, antagonist of α4β2 nAChR, as well as methyllycaconitine, antagonist of α7 and α6β2-containing nAChR, prevented protective effect of varenicline. This together with the presence of α4, α6 and β2 subunit mRNA in the left ventricule of rat heart raises the possibility that the varenicline effect is mediated by α4β2 as well as by α7 and/or α6β2-containing receptors. Our results point to a new way for the use of cytisine and varenicline as cardioprotective agents.

A dual-responsive ratiometric indicator designed for in vivo monitoring of oxidative stress and antioxidant capacity

The imbalance between oxidative stress and antioxidant capacity is strongly associated with the development of numerous degenerative diseases, including cardiovascular diseases, diabetes, neurodegenerative diseases, and cancer. Therefore, monitoring oxidative stress and antioxidant capacity in vivo is crucial for maintaining cellular homeostasis and the stability of the organism's internal environment. Here, we present the findings of our study on DQ1, a dual-responsive indicator designed specifically for imaging H2O2 and NAD(P)H, which are critical indicators of oxidative stress and antioxidant capacity. DQ1 facilitated the colorimetric and fluorescence detection of H2O2 and NAD(P)H in two well-separated channels, exhibiting a detection limit of 1.0 μM for H2O2 and 0.21 nM for NAD(P)H, respectively. Experiments conducted on living cells and zebrafish demonstrated that DQ1 could effectively detect changes in H2O2 and NAD(P)H levels when exposed to exogenous hypoxic conditions and chemical stimuli. Furthermore, the effectiveness of the as-fabricated indicator was investigated in two distinct mouse models: evaluating H2O2 and NAD(P)H levels in myocardial cell dysfunction during acute myocardial infarction and liver tissue damage under trichloroethylene stress conditions. In vivo experiments demonstrated that the levels of the two cardiac biomarkers increase progressively with the development of myocardial infarction, eventually reaching a steady state after 7 days when the damaged cells in the infarcted region become depleted. Moreover, during 14 continuous days of exposure to trichloroethylene, the two biomarkers in liver tissue exhibited a sustained increase, indicating a significant enhancement in intracellular oxidative stress and antioxidant capacity attributed to the mouse liver's robust metabolic capacity. The aforementioned studies underscore the efficacy of DQ1 as a valuable tool for scrutinizing redox states at both the single-cell and biological tissue levels. It presents significant potential for investigating the dynamic alternations in oxidative stress and antioxidant capacity within disease models as the disease progresses, thereby facilitating a more profound comprehension of these processes across various disease models.

Is Intrinsic Cardioprotection a Laboratory Phenomenon or a Clinically Relevant Tool to Salvage the Failing Heart?

Cardiovascular diseases, especially ischemic heart disease, as a leading cause of heart failure (HF) and mortality, will not reduce over the coming decades despite the progress in pharmacotherapy, interventional cardiology, and surgery. Although patients surviving acute myocardial infarction live longer, alteration of heart function will later lead to HF. Its rising incidence represents a danger, especially among the elderly, with data showing more unfavorable results among females than among males. Experiments revealed an infarct-sparing effect of ischemic "preconditioning" (IPC) as the most robust form of innate cardioprotection based on the heart's adaptation to moderate stress, increasing its resistance to severe insults. However, translation to clinical practice is limited by technical requirements and limited time. Novel forms of adaptive interventions, such as "remote" IPC, have already been applied in patients, albeit with different effectiveness. Cardiac ischemic tolerance can also be increased by other noninvasive approaches, such as adaptation to hypoxia- or exercise-induced preconditioning. Although their molecular mechanisms are not yet fully understood, some noninvasive modalities appear to be promising novel strategies for fighting HF through targeting its numerous mechanisms. In this review, we will discuss the molecular mechanisms of heart injury and repair, as well as interventions that have potential to be used in the treatment of patients.

Pharmacological inhibition of the cysteine protease cathepsin C improves graft function after heart transplantation in rats

BACKGROUND

Heart transplantation (HTX) is the standard treatment for end-stage heart failure. However, reperfusion following an ischemic period can contribute to myocardial injury. Neutrophil infiltration, along with the subsequent release of tissue-degrading neutrophil elastase (NE)-related serine proteases and oxygen-derived radicals, is associated with adverse graft outcomes. The inhibition of cathepsin C (CatC) has been shown to block NE-related protease activation. We hypothesized that the CatC inhibitor BI-9740 improves graft function after HTX.

METHODS

In a rat model of HTX, the recipient Lewis rats were orally administered with either a placebo (n = 12) or BI-9740 (n = 11, 20 mg/kg) once daily for 12 days. Donor hearts from untreated Lewis rats were explanted, preserved in a cardioplegic solution, and subsequently heterotopically implanted. In vivo left-ventricular (LV) graft function was assessed after 1 h of reperfusion. The proteolytic activity of neutrophil serine proteases was determined in bone marrow lysates from BI-9740-treated and control rats. Additionally, myocardial morphological changes were examined, and heart samples underwent immunohistochemistry and western blot analysis.

RESULTS

The NE-related proteolytic activity in bone marrow cell lysates was markedly decreased in the BI-9740-treated rats compared to those of the placebo group. Histopathological lesions, elevated CatC and myeloperoxidase-positive cell infiltration, and nitrotyrosine immunoreactivity with an increased number of poly(ADP-ribose) polymerase (PARP)-1-positive cells were lowered in the hearts of animals treated with BI-9740 compared to placebo groups. Regarding the functional parameters of the implanted graft, improvements were observed in both systolic function (LV systolic pressure 110 ± 6 vs 74 ± 6 mmHg; dP/dtmax 2782 ± 149 vs 2076 ± 167 mmHg/s, LV developed pressure, at an intraventricular volume of 200 µl, p < 0.05) and diastolic function in the hearts of BI-9740 treated animals compared with those receiving the only placebo. Furthermore, the administration of BI-9740 resulted in a shorter graft re-beating time compared to the placebo group. However, this study did not provide evidence of DNA fragmentation, the generation of both superoxide anions and hydrogen peroxide, correlating with the absence of protein alterations related to apoptosis, as evidenced by western blot in grafts after HTX.

CONCLUSIONS

We provided experimental evidence that pharmacological inhibition of CatC improves graft function following HTX in rats.

Naringin improves post-ischemic myocardial injury by activation of KATP channels

Naringin (NRG) is a flavonoid with recognized cardioprotective effects. Then, it was investigated the cardioprotective mechanisms of NRG against ischemia-reperfusion (I/R) injury. The rats were pretreated for 7 days (v.o.) with NRG (25 mg/kg) or n-acetylcysteine (NAC, 100 mg/kg) and their isolated hearts were subjected to global ischemia (30 min) and reperfusion (60 min). Furthermore, isolated hearts were perfused with 5 μM NRG in the presence of 10 μM glibenclamide (GLI) and subjected to I/R protocol. In healthy ventricular cardiomyocyte, it was evaluated the acute effect of 5 μM NRG on the GLI sensitive current. The results showed that NRG pretreatment restored the cardiac function and electrocardiogram (ECG) alterations induced by I/R injury, decreasing arrhythmia scores and the occurrence of severe arrhythmias. Lactate dehydrogenase and infarct area were decreased while superoxide dismutase (SOD), catalase and citrate synthase activities increased. Expression of SOD CuZn and SOD Mn not was altered. NRG treatment decreased reactive oxygen species (ROS) generation and lipid peroxidation without alter sulfhydryl groups and protein carbonylation. Also, NRG (5 μM) increased the glibenclamide sensitive current in isolated cardiomyocytes. In isolated heart, the cardioprotection of NRG was significantly reduced by GLI. Furthermore, NRG promoted downregulation of Bax expression and Bax/Bcl-2. Histopathological analysis showed that NRG decreased cell edema, cardiomyocytes and nucleus diameter. Thus, NRG has a cardioprotective effect against cardiac I/R injury which is mediated by its antioxidant and antiapoptotic actions and KATP channels activation.

Potential Role of Natural Antioxidants in Countering Reperfusion Injury in Acute Myocardial Infarction and Ischemic Stroke

Stroke and acute myocardial infarction are leading causes of mortality worldwide. The latter accounts for approximately 9 million deaths annually. In turn, ischemic stroke is a significant contributor to adult physical disability globally. While reperfusion is crucial for tissue recovery, it can paradoxically exacerbate damage through oxidative stress (OS), inflammation, and cell death. Therefore, it is imperative to explore diverse approaches aimed at minimizing ischemia/reperfusion injury to enhance clinical outcomes. OS primarily arises from an excessive generation of reactive oxygen species (ROS) and/or decreased endogenous antioxidant potential. Natural antioxidant compounds can counteract the injury mechanisms linked to ROS. While promising preclinical results, based on monotherapies, account for protective effects against tissue injury by ROS, translating these models into human applications has yielded controversial evidence. However, since the wide spectrum of antioxidants having diverse chemical characteristics offers varied biological actions on cell signaling pathways, multitherapy has emerged as a valuable therapeutic resource. Moreover, the combination of antioxidants in multitherapy holds significant potential for synergistic effects. This study was designed with the aim of providing an updated overview of natural antioxidants suitable for preventing myocardial and cerebral ischemia/reperfusion injuries.

Intramyocardial injection of hypoxia-conditioned extracellular vesicles modulates apoptotic signaling in chronically ischemic myocardium

Objective

Limited treatments exist for nonoperative chronic coronary artery disease. Previously, our laboratory has investigated extracellular vesicle (EV) therapy as a potential treatment for chronic coronary artery disease using a swine model and demonstrated improved cardiac function in swine treated with intramyocardial EV injection. Here, we seek to investigate the potential cardiac benefits of EVs by using hypoxia-conditioned EVs (HEV). Specifically, this study aims to investigate the effect of HEV on apoptosis in chronically ischemic myocardium in swine.

Methods

Fourteen Yorkshire swine underwent placement of an ameroid constrictor on the left circumflex artery. Two weeks later, swine underwent redo left thoracotomy with injection of either saline (control, n = 7) or HEVs (n = 7). After 5 weeks, swine were euthanized for tissue collection. Terminal deoxynucleotidyl transferase dUTP nick end labeling was used to quantify apoptosis. Immunoblotting was used for protein quantification.

Results

Terminal deoxynucleotidyl transferase dUTP nick end labeling staining showed a decrease in apoptosis in the HEV group compared with the control (P = .049). The HEV group exhibited a significant increase in the anti-apoptotic signaling molecule phospho-BAD (P = .005), a significant decrease in B-cell lymphoma 2 (P = .006) and an increase in the phospho-B-cell lymphoma to B-cell lymphoma 2 ratio (P < .001). Furthermore, the HEV group exhibited increased levels of prosurvival signaling markers including phosphoinositide 3-kinase, phosphor-extracellular signal-regulated kinase 1/2, phospho-forkhead box protein O1, and phospho-protein kinase B to protein kinase B ratio (all P < .05).

Conclusions

In chronic myocardial ischemia, treatment with HEV results in a decrease in overall apoptosis, possibly through the activation of both pro-survival and anti-apoptotic signaling pathways.

The Role of Oxidative Stress and Antioxidants in Cardiovascular Comorbidities in COPD

Oxidative stress driven by several environmental and local airway factors associated with chronic obstructive bronchiolitis, a hallmark feature of COPD, plays a crucial role in disease pathomechanisms. Unbalance between oxidants and antioxidant defense mechanisms amplifies the local inflammatory processes, worsens cardiovascular health, and contributes to COPD-related cardiovascular dysfunctions and mortality. The current review summarizes recent developments in our understanding of different mechanisms contributing to oxidative stress and its countermeasures, with special attention to those that link local and systemic processes. Major regulatory mechanisms orchestrating these pathways are also introduced, with some suggestions for further research in the field.

Pharmacological Modulation by Low Molecular Weight Heparin of Purinergic Signaling in Cardiac Cells Prevents Arrhythmia and Lethality Induced by Myocardial Infarction

Background: Although several studies suggest that heparins prevent arrhythmias caused by acute myocardial infarction (AMI), the molecular mechanisms involved remain unclear. To investigate the involvement of pharmacological modulation of adenosine (ADO) signaling in cardiac cells by a low-molecular weight heparin (enoxaparin; ENOX) used in AMI therapy, the effects of ENOX on the incidences of ventricular arrhythmias (VA), atrioventricular block (AVB), and lethality (LET) induced by cardiac ischemia and reperfusion (CIR) were evaluated, with or without ADO signaling blockers. Methods: To induce CIR, adult male Wistar rats were anesthetized and subjected to CIR. Electrocardiogram (ECG) analysis was used to evaluate CIR-induced VA, AVB, and LET incidence, after treatment with ENOX. ENOX effects were evaluated in the absence or presence of an ADO A1-receptor antagonist (DPCPX) and/or an inhibitor of ABC transporter-mediated cAMP efflux (probenecid, PROB). Results: VA incidence was similar between ENOX-treated (66%) and control rats (83%), but AVB (from 83% to 33%) and LET (from 75% to 25%) incidences were significantly lower in rats treated with ENOX. These cardioprotective effects were blocked by either PROB or DPCPX. Conclusion: These results indicate that ENOX was effective in preventing severe and lethal arrhythmias induced by CIR due to pharmacological modulation of ADO signaling in cardiac cells, suggesting that this cardioprotective strategy could be promising in AMI therapy.

Engineering a conduction-consistent cardiac patch with rGO/PLCL electrospun nanofibrous membranes and human iPSC-derived cardiomyocytes

The healthy human heart has special directional arrangement of cardiomyocytes and a unique electrical conduction system, which is critical for the maintenance of effective contractions. The precise arrangement of cardiomyocytes (CMs) along with conduction consistency between CMs is essential for enhancing the physiological accuracy of in vitro cardiac model systems. Here, we prepared aligned electrospun rGO/PLCL membranes using electrospinning technology to mimic the natural heart structure. The physical, chemical and biocompatible properties of the membranes were rigorously tested. We next assembled human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) on electrospun rGO/PLCL membranes in order to construct a myocardial muscle patch. The conduction consistency of cardiomyocytes on the patches were carefully recorded. We found that cells cultivated on the electrospun rGO/PLCL fibers presented with an ordered and arranged structure, excellent mechanical properties, oxidation resistance and effective guidance. The addition of rGO was found to be beneficial for the maturation and synchronous electrical conductivity of hiPSC-CMs within the cardiac patch. This study verified the possibility of using conduction-consistent cardiac patches to enhance drug screening and disease modeling applications. Implementation of such a system could one day lead to in vivo cardiac repair applications.