Targeting necroptotic cell death pathway by high-intensity interval training (HIIT) decreases development of post-ischemic adverse remodelling after myocardial ischemia / reperfusion injury

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.

The Role and Potential Mechanisms of Rehabilitation Exercise Improving Cardiac Remodeling

Rehabilitation exercise is a crucial non-pharmacological intervention for the secondary prevention and treatment of cardiovascular diseases, effectively ameliorating cardiac remodeling in patients. Exercise training can mitigate cardiomyocyte apoptosis, reduce extracellular matrix deposition and fibrosis, promote angiogenesis, and regulate inflammatory response to improve cardiac remodeling. This article presents a comprehensive review of recent research progress, summarizing the pivotal role and underlying mechanism of rehabilitation exercise in improving cardiac remodeling and providing valuable insights for devising effective rehabilitation treatment programs. Graphical Abstract.

Sirt1 Deficiency Promotes Age-Related AF Through Enhancing Atrial Necroptosis by Activation of RIPK1 Acetylation

BACKGROUND

Aging is one of the most potent risk determinants for the onset of atrial fibrillation (AF). Sirts (sirtuins) have been implicated in the pathogenesis of cardiovascular disease, and their expression declines with aging. However, whether Sirts involved in age-related AF and its underlying mechanisms remain unknown. The present study aims to explore the role of Sirts in age-related AF and delineate the underlying molecular mechanisms.

METHODS

Sirt1 levels in the atria of both elderly individuals and aging rats were evaluated using quantitative real-time polymerase chain reaction and Western blot analysis. Mice were engineered to specifically knockout Sirt1 in the atria and right ventricle (Sirt1mef2c/mef2c). Various techniques, such as echocardiography, atrial electrophysiology, and protein acetylation modification omics were employed. Additionally, coimmunoprecipitation was utilized to substantiate the interaction between Sirt1 and RIPK1 (receptor-interacting protein kinase 1).

RESULTS

We discerned that among the diverse subtypes of sirtuin proteins, only Sirt1 expression was significantly diminished in the atria of elderly people and aged rats. The Sirt1mef2c/mef2c mice exhibited an enlarged atrial diameter and heightened vulnerability to AF. Acetylated proteomics and cell experiments identified that Sirt1 deficiency activated atrial necroptosis through increasing RIPK1 acetylation and subsequent pseudokinase MLKL (mixed lineage kinase domain-like protein) phosphorylation. Consistently, necroptotic inhibitor necrosulfonamide mitigated atrial necroptosis and diminished both the atrial diameter and AF susceptibility of Sirt1mef2c/mef2c mice. Resveratrol prevented age-related AF in rats by activating atrial Sirt1 and inhibiting necroptosis.

CONCLUSIONS

Our findings first demonstrated that Sirt1 exerts significant efficacy in countering age-related AF by impeding atrial necroptosis through regulation of RIPK1 acetylation, highlighting that the activation of Sirt1 or the inhibition of necroptosis could potentially serve as a therapeutic strategy for age-related AF.

Pharmacological inhibition of ICOS attenuates the protective effect of exercise on cardiac fibrosis induced by isoproterenol

AIMS

To investigate the cardioprotective mechanism of exercise or exercise combined with inducible costimulatory molecules (ICOS) monoclonal antibody (mAb) therapy against isoproterenol (ISO)-induced cardiac remodeling.

MAIN METHODS

Totally 24 male C57BL/6J mice were randomly divided into four groups: the control group (normal saline treatment), ISO group (subcutaneous injection of isoproterenol, 10 mg/kg/day, once daily for 5 consecutive days), the exercise with subcutaneous ISO injection group (EPI), and the exercise with injected with ISO and ICOS mAb group (EPII). The mice in EPI and EPII group were trained on a small animal treadmill for 4 weeks (13 m/min, 0% grade, 60min/day).

KEY FINDINGS

Exercise significantly attenuated CD45+, Mac-2 inflammatory cell infiltration, cardiac fibrosis and inhibited the RIPK1/RIPK3/MLKL/CaMKII and cardiomyocyte pyroptosis pathways to counter ISO-induced severe cardiac injury. The administration of the ICOS mAb may inhibit the cardioprotection of exercise against ISO-induced heart damage. Compared to those in EPI, our data showed that the increasing levels of myocardial fibrosis, the leukocyte infiltration of cardiac tissue and proteins expression of cardiac myocyte necrosis and pyroptosis signaling pathways in the EPII group.

SIGNIFICANCE

Our results demonstrated that exercise decreased leukocyte infiltration in heart, inhibited the cardiomyocyte pyroptosis and necroptosis signaling pathways, and attenuated inflammatory responses to alleviate ISO-induced cardiac fibrosis. However, the antifibrotic effects of combined treatment with exercise and ICOS mAb intervention did not exhibit synergistic enhancement.

Pharmaceutical Therapies for Necroptosis in Myocardial Ischemia-Reperfusion Injury

Cardiovascular disease morbidity/mortality are increasing due to an aging population and the rising prevalence of diabetes and obesity. Therefore, innovative cardioprotective measures are required to reduce cardiovascular disease morbidity/mortality. The role of necroptosis in myocardial ischemia-reperfusion injury (MI-RI) is beyond doubt, but the molecular mechanisms of necroptosis remain incompletely elucidated. Growing evidence suggests that MI-RI frequently results from the superposition of multiple pathways, with autophagy, ferroptosis, and CypD-mediated mitochondrial damage, and necroptosis all contributing to MI-RI. Receptor-interacting protein kinases (RIPK1 and RIPK3) as well as mixed lineage kinase domain-like pseudokinase (MLKL) activation is accompanied by the activation of other signaling pathways, such as Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), NF-κB, and JNK-Bnip3. These pathways participate in the pathological process of MI-RI. Recent studies have shown that inhibitors of necroptosis can reduce myocardial inflammation, infarct size, and restore cardiac function. In this review, we will summarize the molecular mechanisms of necroptosis, the links between necroptosis and other pathways, and current breakthroughs in pharmaceutical therapies for necroptosis.

Exercise training and experimental myocardial ischemia and reperfusion: A systematic review and meta-analysis

Background

Despite the success of interventional coronary reperfusion strategies, morbidity and mortality from acute myocardial infarction are still substantial. Physical exercise is a well-recognized effective non-pharmacological therapy for cardiovascular diseases. Therefore, the objective of this systematic review was to analyze studies in animal models of ischemia-reperfusion in association with physical exercise protocols.

Search strategy

Articles published on the topic over a 13-year period (2010-2022) were searched in two databases (PubMed and Google Scholar) using the keywords exercise training, ischemia/reperfusion or ischemia reperfusion injury. Meta-analysis and quality assessment of the studies were performed using the Review Manager 5.3 program.

Results

From the 238 articles retrieved from PubMed and 200 from Google Scholar, after screening and eligibility assessment, 26 articles were included in the systematic review and meta-analysis. For meta-analysis comparing the group of previously exercised animals with the non-exercised animals and then submitted to ischemia-reperfusion, the infarct size was significantly decreased by exercise (p < 0.00001). In addition, the group exercised had increased heart-to-body weight ratio (p < 0.00001) and improved ejection fraction as measured by echocardiography (p < 0.0004) in comparison to non-exercised animals.

Conclusion

We concluded that the animal models of ischemia-reperfusion indicates that exercise reduce infarct size and preserve ejection fraction, associated with beneficial myocardial remodeling.

Exercise for myocardial ischemia-reperfusion injury: A systematic review and meta-analysis based on preclinical studies

The main pathological manifestation of coronary artery disease is myocardial injury caused by ischemia-reperfusion (IR) injury. Regular exercise reduces the risk of death during myocardial IR injury. The aim of this study was to describe the effects of various types of exercise on myocardial IR injury. Four electronic databases PubMed, Web of Science, Embase, and Cochrane Library were comprehensively searched from inception until February 2022, to identify studies relevant to the current review, using the method of combining subject and free words. Finally, 16 articles were included in the meta-analysis. Results showed that exercise training decreases the Myocardial infarct size compared to the control group (SMD = -2.6, 95 % CI [-3.53 to -1.67], P < 0.01); increasing the coronary blood flow (MD = 2.93, 95 % CI [2.41 to 3.44], P < 0.01), left ventricular developed pressure (SMD = 2.28, 95 % CI [0.12 to 4.43], P < 0.05), cardiac output (SMD = 1.22, 95 % CI [0.61 to 1.83], P < 0.01) compared to the control group. According to the descriptive analysis results also showed that exercise training increases the left ventricular ejection fraction, superoxide dismutase, manganese superoxide dismutase, glutathione peroxidase, copper-zinc superoxide dismutase, glutathione peroxidase, and decrease the creatine kinase, creatine kinase-MB, lactate dehydrogenase, Malondialdehyde, cardiac troponins T. Exercise can improve myocardial function after myocardial IR injury; however, further research is needed in combination with specific issues such as exercise mode, intensity, duration, and model issues.

Exercise training differently improve cardiac function and regulate myocardial mitophagy in ischemic and pressure-overloaded heart failure mice

NEW FINDINGS

What is the central question of this study? The cardioprotective effects of different aerobic exercises on chronic heart failure with different etiologies and whether mitophagy is involved remain elusive. What is the main finding and its importance? Moderate-intensity continuous training may be the "optimum" modality for improving cardiac structure and function in ischemic heart failure, while both moderate-intensity continuous training and high-intensity interval training were suitable for pressure-overloaded heart failure. Various mitophagy pathways especially PRKN-dependent pathways participated in the protective effects of exercise on heart failure.

ABSTRACT

The cardioprotective effects of different aerobic exercises on chronic heart failure with different etiologies and whether mitophagy is involved remain elusive. In the current research, left anterior descending ligation and transverse aortic constriction surgeries were used to establish mice models of heart failure, followed by 8 weeks of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT). The results showed that MICT significantly improved ejection fraction (P < 0.05) and fractional shortening (P < 0.05), mitigated left ventricular end-systolic dimension (P < 0.01), brain natriuretic peptide (P < 0.0001), and fibrosis (P < 0.0001), while HIIT only decreased brain natriuretic peptide (P < 0.0001) and fibrosis (P < 0.0001) for ischemic heart failure. Both MICT and HIIT significantly increased ejection fraction (P < 0.0001) and fractional shortening (MICT: P < 0.001, HIIT: P < 0.0001), reduced left ventricular end-diastolic and end-systolic dimension, brain natriuretic peptide (P < 0.0001), and fibrosis (MICT: P < 0.01, HIIT: P < 0.0001), even HIIT was better in reducing brain natriuretic peptide on pressure-overloaded heart failure. Myocardial autophagy and mitophagy were compromised in heart failure, exercises improved myocardial autophagic flux and mitophagy inconsistently in heart failure with different etiologies. Significant correlations were found between multiple mitophagy pathways and cardioprotection of exercises. Collectively, MICT may be the "optimum" modality for ischemic heart failure, both MICT and HIIT (especially HIIT) were suitable for pressure-overloaded heart failure. Exercises differently improved myocardial autophagy/mitophagy and multiple mitophagy-related pathways were closely implicated in cardioprotection of exercises for chronic heart failure. This article is protected by copyright. All rights reserved.

Necroptosis is required for atrial fibrillation and involved in aerobic exercise-conferred cardioprotection

Necroptosis, a novel programmed cell death, plays a critical role in the development of fibrosis, yet its role in atrial fibrillation (AF) remains elusive. Mounting evidence demonstrates that aerobic exercise improves AF-related symptoms and quality of life. Therefore, we explored the role of necroptosis in AF pathogenesis and exercise-conferred cardioprotection. A mouse AF model was established either by calcium chloride and acetylcholine (CaCl₂ -Ach) administration for 3 weeks or high-fat diet (HFD) feeding for 12 weeks, whereas swim training was conducted 60 min/day, for 3-week duration. AF susceptibility, heart morphology and function and atrial fibrosis were assessed by electrophysiological examinations, echocardiography and Masson's trichrome staining, respectively. Both CaCl₂ -Ach administration and HFD feeding significantly enhanced AF susceptibility (including frequency and duration of episodes), left atrial enlargement and fibrosis. Moreover, protein levels of necroptotic signaling (receptor-interacting protein kinase 1, receptor-interacting protein kinase 3, mixed lineage kinase domain-like protein and calcium/calmodulin-dependent protein kinase II or their phosphorylated forms) were markedly elevated in the atria of AF mice. However, inhibiting necroptosis with necrostatin-1 partly attenuated CaCl₂ -Ach (or HFD)-induced fibrosis and AF susceptibility, implicating necroptosis as contributing to AF pathogenesis. Finally, we found 3-week swim training inhibited necroptotic signaling, consequently decreasing CaCl₂ -Ach-induced AF susceptibility and atrial structural remodeling. Our findings identify necroptosis as a novel mechanism in AF pathogenesis and highlight that aerobic exercise may confer benefits on AF via inhibiting cardiac necroptosis.

The effect of high-intensity interval training on exercise capacity in post-myocardial infarction patients: a systematic review and meta-analysis

AIMS

Exercise-based cardiac rehabilitation has been recommended a treatment for patients with cardiovascular disease. Nevertheless, it remains controversial which exercise characteristics are most beneficial for post-myocardial infarction (MI) patients. We performed a systematic review and meta-analysis to investigate the effects of high-intensity interval training (HIIT) in these patients.

METHODS AND RESULTS

We searched PubMed, Embase, the Cochrane Library, China National Knowledge Infrastructure (CNKI), Chinese Science and Technology Periodical Database (VIP), and Wanfang Dataset (from the earliest date available to February 2021) for randomized controlled trials and cohort studies that evaluated the effects of HIIT on post-MI patients. Studies were selected according to inclusion and exclusion criteria. Data synthesis was performed with R software version 4.0.1. Eight studies met the study criteria, including 387 patients. Compared to the control group [moderate-intensity continuous training (MICT) and/or routine physical activity], HIIT significantly improved peak oxygen uptake (peak VO2) [mean difference = 3.83 mL/kg/min, 95% confidence interval (CI) (3.25, 4.41), P < 0.01]. No significant difference in systolic and diastolic blood pressures, peak and resting heart rate, left ventricular ejection fraction, left ventricular end-diastolic volume, and the quality of life was found between HIIT group and control group. The duration of follow-up ranged from 6 to 12 weeks. The incidence of adverse events was similar between groups [risk difference = 0.01, 95% CI (-0.02, 0.04), P = 0.53].

CONCLUSION

Compared with MICT and routine physical activity, HIIT could significantly improve exercise capacity in post-MI patients, and appears to be safe.

Human mesenchymal stem cells derived from amniotic membrane attenuate isoproterenol (ISO)-induced myocardial injury by targeting apoptosis

Background: Currently, stem cell therapy has been proposed as an efficient strategy to prevent or treat myocardial injuries. The current study was conducted to examine cardioprotective effects of human mesenchymal stem cells derived from amniotic membrane (hAMSCs) against isoproterenol (ISO)-induced myocardial injury and explore its potential mechanisms. Methods: The hAMSCs were injected intramyocardially in male Wistar rats 28 days after last injection of ISO (170 mg/kg body weight for 4 consecutive days). The echocardiography was performed to confirm induction of myocardial damage and cardiac function 28 days after last injection of ISO and 4 weeks hAMSCs transplantation after HF induction. The expression of apoptotic markers such as Bcl-2, Bax and P53 was evaluated using Western blotting assay. Masson's trichrome staining was used to determine fibrosis. The cytoarchitecture of myocardial wall and morphology of cells were investigated using hematoxylin and eosin (H&E) staining. Results: As compared to ISO group, hAMSCs transplantation after heart failure (HF) induction significantly blunted the increasing of cardiac dimensions and restored ejection fraction (EF) and fractional shortening (FS) parameters (p<0.05). Moreover, hAMSCs transplantation after HF induction increased the expression of antiapoptotic markers such as Bcl-2 and decreased the expression of pro-apoptotic markers such as P53 and Bax (p<0.05). As compared to ISO group, hAMSCs transplantation after HF induction markedly reduced interstitial myocardial fibrosis and contributed to maintain of normal cytoarchitecture of myocardial wall and morphology of cells. Conclusion: Collectively, the results of current study suggest that transplantation of hAMSCs confers cardioprotection by targeting ISO-induced mitochondria-dependent (intrinsic) pathway of apoptosis.

Ferroptosis Is a Potential Novel Diagnostic and Therapeutic Target for Patients With Cardiomyopathy

Cardiomyocyte death is a fundamental progress in cardiomyopathy. However, the mechanism of triggering the death of myocardial cells remains unclear. Ferroptosis, which is the nonapoptotic, iron-dependent, and peroxidation-driven programmed cell death pathway, that is abundant and readily accessible, was not discovered until recently with a pharmacological approach. New researches have demonstrated the close relationship between ferroptosis and the development of many cardiovascular diseases, and several ferroptosis inhibitors, iron chelators, and small antioxidant molecules can relieve myocardial injury by blocking the ferroptosis pathways. Notably, ferroptosis is gradually being considered as an important cell death mechanism in the animal models with multiple cardiomyopathies. In this review, we will discuss the mechanism of ferroptosis and the important role of ferroptosis in cardiomyopathy with a special emphasis on the value of ferroptosis as a potential novel diagnostic and therapeutic target for patients suffering from cardiomyopathy in the future.

Human amniotic membrane mesenchymal stem cells exert cardioprotective effects against isoproterenol (ISO)-induced myocardial injury through suppression of inflammation and modulation of inflammatory MAPK/NF-κB pathway

A common cause of mortality around the world is ischemic myocardial injury. The study was conducted to examine the ability of amniotic membrane mesenchymal stem cells (AMSCs) for protection against isoproterenol (ISO)-induced myocardial injury and attempted to show the possible mechanisms by which AMSCs that can be linked to inhibition of inflammation by targeting inflammatory MAPK/NF-κB pathway. Model was established by subcutaneous injection of 170 mg/kg/day of ISO for four consecutive days. Flow cytometry and echocardiography were carried out to evaluate characterization of hAMSCs and cardiac function, respectively. The expression of inflammatory cytokines was determined using ELISA assay. The activities of NF-κB and phosphorylated p38 MAPK were measured using immunohistochemical assessments. The results showed that ISO administration was resulted in cardiac dysfunction, increased levels of inflammatory cytokines that reversed by intramyocardially administration of AMSCs (P < 0. 05). Cardioprotective effects of AMSCs were associated with a significant decreased expression of NF-κB and reduced levels of phosphorylated p38 MAPK (P < 0. 05). In conclusion, our finding showed that intramyocardially administration of AMSCs could contribute to improvement of heart function and inhibition of inflammation in the site of injury by targeting inflammatory MAPK/NF-κB pathway.

Necroptosis and RhoA/ROCK pathways: molecular targets of Nesfatin-1 in cardioprotection against myocardial ischemia/reperfusion injury in a rat model

Nesfatin-1 as a new energy-regulating peptide has been known to display a pivotal role in modulation of cardiovascular functions and protection against ischemia/reperfusion injury. However, the detailed knowledge about molecular mechanisms underlying this protection has not been completely investigated yet. This study was designed to clarify the molecular mechanisms by which nesfatin-1 exert cardioprotection effects against myocardial ischemia-reperfusion (MI/R). Left anterior descending coronary artery (LAD) was ligated for 30 min to create a MI/R model in rats. MI/R rats were treated with three concentrations of nesfatin-1 (10, 15 and 20 µg/kg) then expression of necroptosis and necrosis mediators were measured by western blotting assay. Fibrosis, morphological damages, cardiac function, myocardial injury indictors and oxidative stress factors were evaluated as well. Induction of MI/R model resulted in cardiac dysfunction, oxidative stress, increased activity of RIPK1-RIPK3-MLKL axis and RhoA/ROCK pathway, extension of fibrosis and heart tissue damage. Highest tested concentration of nesfatin-1 markedly improved cardiac function. Moreover, it reduced oxidative stress, collagen deposition, and morphological damages, through inhibiting the expression of necroptosis mediators and also, necrosis including RIPK1, RIPK3, MLKL, ROCK1, and ROCK2 proteins. The lowest and middle tested concentrations of nesfatin-1 failed to exert protective effects against MI/R. These findings have shown that nesfatin-1 can exert cardioprotection against MI/R in a dose dependent manner by suppressing necroptosis via modulation of RIPK1-RIPK3-MLKL axis and RhoA/ROCK/RIP3 signaling pathway.

Endothelial to Mesenchymal Transition in the Cardiogenesis and Cardiovascular Diseases

Today, cardiovascular diseases remain a leading cause of morbidity and mortality worldwide. Endothelial to mesenchymal transition (EndMT) does not only play a major role in the course of development but also contributes to several cardiovascular diseases in adulthood. EndMT is characterized by down-regulation of the endothelial proteins and highly up-regulated fibrotic specific genes and extracellular matrix-forming proteins. EndMT is also a transforming growth factor-β-driven (TGF-β) process in which endothelial cells lose their endothelial characteristics and acquire a mesenchymal phenotype with expression of α-smooth muscle actin (α-SMA), fibroblast-specific protein 1, etc. EndMT is a vital process during cardiac development, thus disrupted EndMT gives rise to the congenital heart diseases, namely septal defects and valve abnormalities. In this review, we have discussed the main signaling pathways and mechanisms participating in the process of EndMT such as TGF-β and Bone morphogenetic protein (BMP), Wnt^#, and Notch signaling pathway and also studied the role of EndMT in physiological cardiovascular development and pathological conditions including myocardial infarction, pulmonary arterial hypertension, congenital heart defects, cardiac fibrosis, and atherosclerosis. As a perspective view, having a clear understanding of involving cellular and molecular mechanisms in EndMT and conducting Randomized controlled trials (RCTs) with a large number of samples for involving pharmacological agents may guide us into novel therapeutic approaches of congenital disorders and heart diseases.

The role of RIPK3-regulated cell death pathways and necroptosis in the pathogenesis of cardiac ischaemia-reperfusion injury

Despite advancements in management of acute myocardial infarction, this disease remains one of the leading causes of death. Timely reestablishment of epicardial coronary blood flow is the cornerstone of therapy; however, substantial amount of damage can occur as a consequence of cardiac ischaemia/reperfusion (I/R) injury. It has been previously proposed that the pathway leading to major cell death, apoptosis, is responsible for cardiac I/R injury. Nevertheless, there is compelling evidence to suggest that necroptosis, a programmed necrosis, contributes remarkably to both myocardial injury and microcirculatory dysfunction following cardiac I/R injury. Receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed-lineage kinase domain-like pseudokinase (MLKL) are shown as the major mediators of necroptosis. In addition to the traditional perception that RIPK1/RIPK3/MLKL-dependent plasma membrane rupture is fundamental to this process, several RIPK3-related pathways such as endoplasmic reticulum stress and mitochondrial fragmentation have also been implicated in cardiac I/R injury. In this review, reports from both in vitro and in vivo studies regarding the roles of necroptosis and RIPK3-regulated necrosis in cardiac I/R injury have been collectively summarized and discussed. Furthermore, reports on potential interventions targeting these processes to attenuate cardiac I/R insults to the heart have been presented in this review. Future investigations adding to the knowledge obtained from these previous studies are needed in the pursuit of discovering the most effective pharmacological agent to improve cardiac I/R outcomes.

Targeting the pathways of regulated necrosis: a potential strategy for alleviation of cardio-cerebrovascular injury

Apoptosis, necrosis and autophagy-dependent cell death are the three major types of cell death. Traditionally, necrosis is thought as a passive and unregulated form of cell death. However, certain necrosis can also occur in a highly regulated manner, referring to regulated necrosis. Depending on the signaling pathways, regulated necrosis can be further classified as necroptosis, pyroptosis, ferroptosis, parthanatos and CypD-mediated necrosis. Numerous studies have reported that regulated necrosis contributes to the progression of multiple injury-relevant diseases. For example, necroptosis contributes to the development of myocardial infarction, atherosclerosis, heart failure and stroke; pyroptosis is involved in the progression of myocardial or cerebral infarction, atherosclerosis and diabetic cardiomyopathy; while ferroptosis, parthanatos and CypD-mediated necrosis participate in the pathological process of myocardial and/or cerebral ischemia/reperfusion injury. Thereby, targeting the pathways of regulated necrosis pharmacologically or genetically could be an efficient strategy for reducing cardio-cerebrovascular injury. Further study needs to focus on the crosstalk and interplay among different types of regulated necrosis. Pharmacological intervention of two or more types of regulated necrosis simultaneously may have advantages in clinic to treat injury-relevant diseases.

High-intensity interval training-induced hypertrophy in gastrocnemius muscle via improved IGF-I/Akt/FoxO and myostatin/Smad signaling pathways in rats

Objective

It has been shown that high-intensity interval training (HIIT) leads to skeletal muscle hypertrophy; however, its mechanisms of cellular and molecular regulation are still unclear. The purpose of this study was to investigate the effect of HIIT on muscle hypertrophy and major signal transduction pathways.

Design

12 male rats were randomly divided into two groups: control and HIIT. The exercise group performed 30-min HIIT in each session (5 × 4-min intervals running at 85-95% VO2max separated by 2-min active rest at 55-60% VO2max), 3 days/week for 8 weeks. Muscle fiber cross-sectional area (CSA) and the expression of signal transduction pathway proteins were determined in the gastrocnemius muscle.

Results

In the HIIT group, the expression of IGF-I, IGF-IR Akt, p-Akt, AMPKα, p-AMPKα and follistatin increased significantly, whereas a significant decrease was observed in the expression of FoxO1, p-FoxO1, myostatin, ActRIIB, Smad2/3 and p-Smad2/3 (P < 0.05). However, there were no significant differences between the HIIT and control groups in the expression of mTOR, p-mTOR, P70S6K, and p-P70S6K (P > 0.05). In addition, CSA and gastrocnemius muscle weight increased significantly in the HIIT group (P < 0.05).

Conclusions

HIIT induced muscle hypertrophy by improving IGF-I/Akt/FoxO and myostatin/Smad signal transduction pathways.

Amniotic membrane mesenchymal stem cells labeled by iron oxide nanoparticles exert cardioprotective effects against isoproterenol (ISO)-induced myocardial damage by targeting inflammatory MAPK/NF-κB pathway

The aim of the present study is to investigate the protective effects of human amniotic membrane-derived mesenchymal stem cells (hAMSCs) labeled by superparamagnetic iron oxide nanoparticles (SPIONs) against isoproterenol (ISO)-induced myocardial injury in the presence and absence of a magnetic field. ISO was injected subcutaneously for 4 consecutive days to induce myocardial injury in male Wistar rats. The hAMSCs were incubated with 100 μg/ml SPIONs and injected to rats in magnet-dependent and magnet-independent groups via the tail vein. The size and shape of nanoparticles were determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Prussian blue staining was used to determine cell uptake of nanoparticles. Myocardial fibrosis, heart function, characterization of hAMSCs, and histopathological changes were determined using Masson's trichrome, echocardiography, flow cytometry, and H&E staining, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to the expression pro-inflammatory cytokines. Immunohistochemistry assay was used to determine the expression of nuclear factor-κB (NF-κB) and the Ras/mitogen-activated protein kinase (MAPK). SPION-labeled MSCs in the presence of magnetic field significantly improved cardiac function and reduced fibrosis and tissue damage by suppressing inflammation in a NF-κB/MAPK-dependent mechanism (p < 0. 05). Collectively, our findings demonstrate that SPION-labeled MSCs in the presence of magnetic field can be a good treatment option to reduce inflammation following myocardial injury. Graphical abstract.

Mitochondrial and mitochondrial-independent pathways of myocardial cell death during ischaemia and reperfusion injury

Acute myocardial infarction causes lethal injury to cardiomyocytes during both ischaemia and reperfusion (IR). It is important to define the precise mechanisms by which they die in order to develop strategies to protect the heart from IR injury. Necrosis is known to play a major role in myocardial IR injury. There is also evidence for significant myocardial death by other pathways such as apoptosis, although this has been challenged. Mitochondria play a central role in both of these pathways of cell death, as either a causal mechanism is the case of mitochondrial permeability transition leading to necrosis, or as part of the signalling pathway in mitochondrial cytochrome c release and apoptosis. Autophagy may impact this process by removing dysfunctional proteins or even entire mitochondria through a process called mitophagy. More recently, roles for other programmed mechanisms of cell death such as necroptosis and pyroptosis have been described, and inhibitors of these pathways have been shown to be cardioprotective. In this review, we discuss both mitochondrial and mitochondrial‐independent pathways of the major modes of cell death, their role in IR injury and their potential to be targeted as part of a cardioprotective strategy. This article is part of a special Issue entitled ‘Mitochondria as targets of acute cardioprotection’ and emerged as part of the discussions of the European Union (EU)‐CARDIOPROTECTION Cooperation in Science and Technology (COST) Action, CA16225.

Redox Epiphospholipidome in Programmed Cell Death Signaling: Catalytic Mechanisms and Regulation

A huge diversification of phospholipids, forming the aqueous interfaces of all biomembranes, cannot be accommodated within a simple concept of their role as membrane building blocks. Indeed, a number of signaling functions of (phospho)lipid molecules has been discovered. Among these signaling lipids, a particular group of oxygenated polyunsaturated fatty acids (PUFA), so called lipid mediators, has been thoroughly investigated over several decades. This group includes oxygenated octadecanoids, eicosanoids, and docosanoids and includes several hundreds of individual species. Oxygenation of PUFA can occur when they are esterified into major classes of phospholipids. Initially, these events have been associated with non-specific oxidative injury of biomembranes. An alternative concept is that these post-synthetically oxidatively modified phospholipids and their adducts with proteins are a part of a redox epiphospholipidome that represents a rich and versatile language for intra- and inter-cellular communications. The redox epiphospholipidome may include hundreds of thousands of individual molecular species acting as meaningful biological signals. This review describes the signaling role of oxygenated phospholipids in programs of regulated cell death. Although phospholipid peroxidation has been associated with almost all known cell death programs, we chose to discuss enzymatic pathways activated during apoptosis and ferroptosis and leading to peroxidation of two phospholipid classes, cardiolipins (CLs) and phosphatidylethanolamines (PEs). This is based on the available LC-MS identification and quantitative information on the respective peroxidation products of CLs and PEs. We focused on molecular mechanisms through which two proteins, a mitochondrial hemoprotein cytochrome c (cyt c), and non-heme Fe lipoxygenase (LOX), change their catalytic properties to fulfill new functions of generating oxygenated CL and PE species. Given the high selectivity and specificity of CL and PE peroxidation we argue that enzymatic reactions catalyzed by cyt c/CL complexes and 15-lipoxygenase/phosphatidylethanolamine binding protein 1 (15LOX/PEBP1) complexes dominate, at least during the initiation stage of peroxidation, in apoptosis and ferroptosis. We contrast cell-autonomous nature of CLox signaling in apoptosis correlating with its anti-inflammatory functions vs. non-cell-autonomous ferroptotic signaling facilitating pro-inflammatory (necro-inflammatory) responses. Finally, we propose that small molecule mechanism-based regulators of enzymatic phospholipid peroxidation may lead to highly specific anti-apoptotic and anti-ferroptotic therapeutic modalities.

Guidelines for evaluating myocardial cell death

Cell death is a fundamental process in cardiac pathologies. Recent studies have revealed multiple forms of cell death, and several of them have been demonstrated to underlie adverse cardiac remodeling and heart failure. With the expansion in the area of myocardial cell death and increasing concerns over rigor and reproducibility, it is important and timely to set a guideline for the best practices of evaluating myocardial cell death. There are six major forms of regulated cell death observed in cardiac pathologies, namely apoptosis, necroptosis, mitochondrial-mediated necrosis, pyroptosis, ferroptosis, and autophagic cell death. In this article, we describe the best methods to identify, measure, and evaluate these modes of myocardial cell death. In addition, we discuss the limitations of currently practiced myocardial cell death mechanisms.

High-intensity interval training increase GATA4, CITED4 and c-Kit and decreases C/EBPβ in rats after myocardial infarction

AIM

Myocardial infarction (MI), an important cause of morbidity and mortality, can be followed by left ventricular dysfunction and cardiomyocyte loss. Cardiac repair mechanisms may subsequently improve left ventricular function. Exercise training has been suggested to have cardioprotective effects against MI damage, but detailed knowledge is lacking on the effects of different types and intensities of exercise training on molecular targets of cardiomyocyte regeneration.

MAIN METHODS

MI was induced in male Wistar rats by ligating the left anterior descending coronary artery. After MI induction, the rats were randomly assigned to one of five groups: sham operated, and experimental MI followed by no exercise, or low, moderate or high intensity exercise Cardiac function and infarct size were assessed by echocardiography and Evans blue/TTC staining, respectively. The expression of mRNA markers and proteins associated with myocardial regeneration was measured with RT-PCR and western blotting.

KEY FINDINGS

Exercise training at different intensities improved cardiac function and levels of stem cell and cardiomyocyte markers, and reduced infarct size. mRNA levels of GATA4, Nkx2.5 and c-Kit and protein expression of Nkx2.5 and c-Kit were significantly increased in all MI-exercise groups. The high-intensity exercise group had greater increases than the low and moderate intensity exercise groups. In the high-intensity exercise group, Sca-1 and CITED4 increased more than in the low-intensity exercise group. C/EBPβ mRNA and protein levels decreased after exercise training, with greater reductions in the high-intensity exercise group than the low- or moderate-intensity groups.

SIGNIFICANCE

The findings suggest that by targeting cardiogenesis, high-intensity training can exert cardioprotective effects against cardiac dysfunction in an experimental model of MI.

Novel Aspects of Cardiac Ischemia and Reperfusion Injury Mechanisms

Introduction.The present article, in which a contemporary analysis of the literature on the pathophysiology of ischemic and reperfusion injury (IRI) of the myocardium is presented, focuses on the possible role played by of the calpain system and oxidative stress. Several process development options were proposed, including cytosolic and mitochondrial Ca2+ overload, reactive oxygen stress release, acute inflammatory response and metabolic degradation. The combined effect of all of the above factors produces irreversible ischemic and reperfused damage of cardiomyocytes.Materials and methods.The role of the calpain system in the creation of myocardial IRI was experimentally investigated. It was found that active calpain substrates play a significant role in the processes of cell cycle, apoptosis and differentiation, adversely affecting cardiomyocyte functionality. The calpain system is part of an integrated proteolytic system that is critical to the relationship between the structure and function of the cardiac sarcomere. Uncontrolled activation of calpain is indicated in the pathophysiology of many cardiovascular disorders. As shown by research, inhibitor calpain reduces the size of the zone of infarction following ischemia reperfusion and thus lessens the risk of “stunning” the myocardium. As is known, a consequence of IRI is acute myocardial infarction (AMI), which is a central factor in cardiovascular disease (CVD) and is one of the primary causes of mortality. Understanding the exact pathophysiological mechanisms remains an urgent problem for clinical physicians. To date, the mechanisms of IRI are not fully known, which creates certain difficulties in further treatment and prevention tactics. In addition, myocardial IRI is also an important issue for pathoanatomical service, since sudden coronary death can occur despite timely reperfusion therapy following AMI.Conclusion.The development of strategies for creating conditions that limit the degree of damage to myocardial tissues significantly increases the ability of the heart to withstand ischemic damage.