NIPAAm-MMA nanoparticle-encapsulated visnagin ameliorates myocardial ischemia/reperfusion injury through the promotion of autophagy and the inhibition of apoptosis

Salviae miltiorrhizae Liguspyragine Hydrochloride and Glucose Injection Protects against Myocardial Ischemia-Reperfusion Injury and Heart Failure

Purpose

Myocardial ischemia-reperfusion (MIR) injury is a common stimulus for cardiac diseases like cardiac arrhythmias and heart failure and may cause high mortality rates. Salviae miltiorrhizae liguspyragine hydrochloride and glucose injection (SGI) has been widely used to treat myocardial and cerebral infarctions in China even though its pharmacological mechanisms are not completely clear.

Methods

The protective effect and mechanism of SGI on MIR injury and heart failure were investigated through the H9c2 cell model induced by hypoxia/reoxygenation (H/R) and rapamycin, zebrafish model induced by H/R and isoprenaline, and rat MIR model.

Results

SGI significantly reduced the infarct size and alleviated the impairment of cardiac functions in the MIR rat model and H/R zebrafish model and promoted cell viability of cardiomyocyte-like H9c2 cells under H/R condition. Consistently, SGI significantly downregulated the serum level of biomarkers for cardiac damage and attenuated the oxidative damage in the MIR and H/R models. We also found that SGI could downregulate the increased autophagy level in those MIR and H/R models since autophagy can contribute to the injurious effects of ischemia-reperfusion in the heart, suggesting that SGI may alleviate MIR injury via regulating the autophagy pathway. In addition, we demonstrated that SGI also played a protective role in the isoproterenol-induced zebrafish heart failure model, and SGI significantly downregulated the increased autophagy and SP1/GATA4 pathways.

Conclusion

SGI may exert anti-MIR and heart failure by inhibiting activated autophagy and the SP1/GATA4 pathway.

Blunting TRPML1 channels protects myocardial ischemia/reperfusion injury by restoring impaired cardiomyocyte autophagy

Accumulating evidence suggests that autophagy dysfunction plays a critical role in myocardial ischemia/reperfusion (I/R) injury. However, the underling mechanism of malfunctional autophagy in the cardiomyocytes subjected to I/R has not been well defined. As a result, there is no effective therapeutic option by targeting autophagy to prevent myocardial I/R injury. Here, we used both an in vitro and an in vivo I/R model to monitor autophagic flux in the cardiomyocytes, by exposing neonatal rat ventricular myocytes to hypoxia/reoxygenation and by subjecting mice to I/R, respectively. We observed that the autophagic flux in the cardiomyocytes subjected to I/R was blocked in both in vitro and in vivo models. Down-regulating a lysosomal cationic channel, TRPML1, markedly restored the blocked myocardial autophagic flux induced by I/R, demonstrating that TRPML1 directly contributes to the blocked autophagic flux in the cardiomyocytes subjected to I/R. Mechanistically, TRPML1 is activated secondary to ROS elevation following ischemia/reperfusion, which in turn induces the release of lysosomal zinc into the cytosol and ultimately blocks the autophagic flux in cardiomyocytes, presumably by disrupting the fusion between autophagosomes and lysosomes. As a result, the inhibited myocardial autophagic flux induced by TRPML1 disrupted mitochondria turnover and resulted in mass accumulation of damaged mitochondria and further ROS release, which directly led to cardiomyocyte death. More importantly, pharmacological and genetic inhibition of TRPML1 channels greatly reduced infarct size and rescued heart function in mice subjected to I/R in vivo by restoring impaired myocardial autophagy. In summary, our study demonstrates that secondary to ROS elevation, activation of TRPML1 results in autophagy inhibition in the cardiomyocytes subjected to I/R, which directly leads to cardiomyocyte death by disrupting mitochondria turnover. Therefore, targeting TRPML1 represents a novel therapeutic strategy to protect against myocardial I/R injury.

Animal models used in the research of nanoparticles for cardiovascular diseases

Cardiovascular disease (CVD) is the leading cause of mortality and morbidity worldwide. Tremendous progress has been made in the prevention and treatment of CVD; however, there are still lots of limitations and new technology is needed. Nanoparticles have been studied recently for CVD due to their nanoscale size and unique properties, and hold a potential to be a novel therapy for the treatment. To test the safety and effectiveness of drug-loaded nanoparticles for CVD prior to human studies, animal disease models are unavoidably needed. This review summarized the animal models used in the research of nanoparticles for CVD and provided a generic picture of current use of CVD animal models according to the different types of diseases which should be prioritized when considering the application of nanoparticles in treating CVD. This review would be useful resources not only for life science researchers and clinicians but also for those from chemistry and materials sciences background who may not have a systematic knowledge about CVD animal models.

The potentials of distinct functions of autophagy to be targeted for attenuation of myocardial ischemia/reperfusion injury in preclinical studies: an up-to-date review

Despite remarkable advances in our knowledge about the function of autophagy in myocardial ischemia/reperfusion (I/R) injury, the debate continues over whether autophagy is protective or deleterious in cardiac I/R. Due to the complexity of autophagy signaling, autophagy can play a dual role in the pathological processes of myocardial I/R injury. Thus, more researches are needed to shed light on the complex roles of autophagy in cardioprotection for the future clinical development. Such researches can lead to the finding of new therapeutic strategies for improving cardiac I/R outcomes in patients. Several preclinical studies have targeted autophagy flux as a beneficial strategy against myocardial I/R injury. In this review, we aimed to discuss the complex contribution of autophagy in myocardial I/R injury, as well as the therapeutic agents that have been shown to be useful in reducing myocardial I/R injury by targeting autophagy. For this reason, we provided an updated summary of the data from in vivo, ex vivo, and in vitro experimental studies about the therapeutic agents that exert positive effects against myocardial I/R injury by modulating autophagy flux. By addressing these valuable studies, we try to provide a motivation for the promising hypothesis of "autophagy modulation as a therapeutic strategy against cardiac I/R" in the future clinical studies.

Potential Biotechnological Applications of Autophagy for Agriculture

Autophagy is a genetically regulated, eukaryotic cellular degradation system that sequestrates cytoplasmic materials in specialised vesicles, termed autophagosomes, for delivery and breakdown in the lysosome or vacuole. In plants, autophagy plays essential roles in development (e.g., senescence) and responses to abiotic (e.g., nutrient starvation, drought and oxidative stress) and biotic stresses (e.g., hypersensitive response). Initially, autophagy was considered a non-selective bulk degradation mechanism that provides energy and building blocks for homeostatic balance during stress. Recent studies, however, reveal that autophagy may be more subtle and selectively target ubiquitylated protein aggregates, protein complexes and even organelles for degradation to regulate vital cellular processes even during favourable conditions. The selective nature of autophagy lends itself to potential manipulation and exploitation as part of designer protein turnover machinery for the development of stress-tolerant and disease-resistant crops, crops with increased yield potential and agricultural efficiency and reduced post-harvest losses. Here, we discuss our current understanding of autophagy and speculate its potential manipulation for improved agricultural performance.

Ischemia Reperfusion Injury: Opportunities for Nanoparticles

Ischemia reperfusion (IR)-induced oxidative stress, accompanied by inflammatory responses, contributes to morbidity and mortality in numerous diseases such as acute coronary syndrome, stroke, organ transplantation, and limb injury. Ischemia results in profound hypoxia and tissue dysfunction, whereas subsequent reperfusion further aggravates ischemic tissue damage through inducing cell death and activating inflammatory responses. In this review, we highlight recent studies of therapeutic strategies against IR injury. Furthermore, nanotechnology offers significant improvements in this area. Hence, we also review recent advances in nanomedicines for IR therapy, suggesting them as potent and promising strategies to improve drug delivery to IR-injured tissues and achieve protective effects.

BW373U86 upregulates autophagy by inhibiting the PI3K/Akt pathway and regulating the mTOR pathway to protect cardiomyocytes from hypoxia-reoxygenation injury

The purpose of this study was to explore the protective effect of BW373U86 (a δ-opioid receptor (DOR) agonist) on ischemia-reperfusion (I/R) injury in rat cardiomyocytes and its underlying mechanism. Primary rat cardiomyocytes were cultured and pretreated with BW373U86 for intervention. The cardiomyocytes were cultured under the condition of 94% N₂ and 5% CO₂ for 24 h to perform hypoxia culture and conventionally cultured for 12 h to perform reoxygenation culture. The cell viability of cardiomyocytes was detected by an MTT assay (Sigma-Aldrich). The autophagy lysosome levels in cardiomyocytes were evaluated by acidic vesicular organelles with dansylcadaverine (MDC) staining (autophagy test kit, Kaiji Biology, kgatg001). The protein expression levels of LC3, p62, and factors in the PI3K/Akt/mTOR signaling pathway were detected by Western blot. Pretreatment with BW373U86 could improve the cell viability of cardiomyocytes with hypoxia-reoxygenation (H/R) injury (p < 0.05). Interestingly, after coculture of BW373U86 and PI3K inhibitor (3-methyladenine), the protein expression levels of p-Akt in cardiomyocytes were markedly increased in comparison with those in the BW373U86 group (p < 0.05). However, there were no significant differences in the protein expression levels of mTOR between the coculture group and the BW373U86 group (p > 0.05). BW373U86 upregulated autophagy to protect cardiomyocytes from H/R injury, which may be related to the PI3K/Akt/m TOR pathway.

The Role of Autophagy in Acute Myocardial Infarction

Acute myocardial infarction refers to a sudden death of cardiomyocytes, which leads to a large mortality worldwide. To attenuate acute myocardial infarction, strategies should be made to increase cardiomyocyte survival, improve postinfarcted cardiac function, and reverse the process of cardiac remodeling. Autophagy, a pivotal cellular response, has been widely studied and is known to be involved in various kinds of diseases. In the recent few years, the role of autophagy in diseases has been drawn increasing attention to by researchers. Here in this review, we mainly focus on the discussion of the effect of autophagy on the pathogenesis and progression of acute myocardial infarction under ischemic and ischemia/reperfusion injuries. Furthermore, several popular therapeutic agents and strategies taking advantage of autophagy will be described.

MiR-103 inhibiting cardiac hypertrophy through inactivation of myocardial cell autophagy via targeting TRPV3 channel in rat hearts

Cardiac hypertrophy is a common pathological change frequently accompanied by chronic hypertension and myocardial infarction. Nevertheless, the pathophysiological mechanisms of cardiac hypertrophy have never been elucidated. Recent studies indicated that miR-103 expression was significantly decreased in heart failure patients. However, less is known about the role of miR-103 in cardiac hypertrophy. The present study was designed to investigate the relationship between miR-103 and the mechanism of pressure overload-induced cardiac hypertrophy. TRPV3 protein, cardiac hypertrophy marker proteins (BNP and β-MHC) and autophagy associated proteins (Beclin-1 and LC3-II) were up-regulated, as well as, miR-103 expression and autophagy associated proteins (p62) were down-regulated in cardiac hypertrophy models in vivo and in vitro respectively. Further results indicated that silencing TRPV3 or forcing overexpression of miR-103 could dramatically inhibit cell surface area, relative fluorescence intensity of Ca2+ signal and the expressions of BNP, β-MHC, Beclin-1 and LC3-II, but promote p62 expression. Moreover, TRPV3 protein was decreased in neonatal rat ventricular myocyte transfected with miR-103, but increased by AMO-103. Co-transfection of the miR-103 with the luciferase reporter vector into HEK293 cells caused a sharp decrease in luciferase activity compared with transfection of the luciferase vector alone. The miR-103-induced depression of luciferase activity was rescued by an AMO-103. These findings suggested that TRPV3 was a direct target of miR-103. In conclusion, miR-103 could attenuate cardiomyocyte hypertrophy partly by reducing cardiac autophagy activity through the targeted inhibition of TRPV3 signalling in the pressure-overloaded rat hearts.

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.