Pyroptosis in myocardial ischemia/reperfusion and its therapeutic implications

Salvia miltiorrhiza-derived exosome-like nanoparticles improve diabetic cardiomyopathy by inhibiting NLRP3 inflammasome-mediated macrophage pyroptosis via targeting the NEDD4/SGK1 axis

AIM

Exosome-like nanoparticles mediate intercellular communication and regulate gene expression. In this study, we isolated and purified exosome-like nanoparticles from Salvia miltiorrhiza (SM-ELNs), a traditional Chinese medicinal herb, and investigated their therapeutic effects on diabetic cardiomyopathy (DCM).

MATERIALS & METHODS

To investigate the effect of SM-ELNs on DCM, we established a mouse model via HFD/STZ treatment. Cardiac function was assessed by echocardiography. Cardiac hypertrophy was assessed by measuring the heart weight/body weight ratio and HE staining, while myocardial fibrosis was evaluated using Masson's trichrome staining. The role of SM-ELNs on NLRP3 inflammasome inhibition and macrophage pyroptosis were evaluated both in vivo and in vitro. The interaction between NEDD4 and SGK1 was analyzed by Co-IP and ubiquitination assays.

RESULTS

SM-ELNs treatment alleviated cardiac function and histopathological changes in DCM mice. Moreover, SM-ELNs suppressed NLRP3 inflammasome activation and subsequent macrophage pyroptosis in both in vivo and in vitro models. Mechanistically, NEDD4 facilitated the ubiquitination and degradation of SGK1 in macrophages. Both NEDD4 depletion and SGK1 addition could counteract the SM-ELNs-induced suppression of NLRP3 inflammasome-triggered macrophage pyroptosis in LPS/ATP-treated RAW264.7 cells.

CONCLUSION

Our study provides the first evidence that SM-ELNs inhibit NLRP3 inflammasome-mediated macrophage pyroptosis in DCM by modulating the NEDD4/SGK1 axis.

Mangiferin Attenuates Myocardial Ischemia Reperfusion Injury by Regulating the GAS6/Axl Signaling Pathway

Ischemia reperfusion-induced myocardial injury is a prominent pathological feature in patients with coronary artery disease, contributing to significant mortality and morbidity rates. Mangiferin (MGF), the main active ingredient extracted from Anemarrhena asphodeloides Bge, has anti-inflammatory, anti-oxidation, anti-diabetes, and anti-tumor effects. The present study confirmed that the GAS6/Axl pathway was identified as a promising novel target for the treatment of myocardial ischemia reperfusion (IR) injury. However, whether MGF exerts anti-myocardial ischemia reperfusion injury through GAS6/Axl is still unclear. In this study, BALB/c male mice and HL-1 cardiomyocytes were used to construct a model of IR and hypoxia-reoxygenation (HR) (or H2O2) injury in vivo and in vitro, respectively. MGF significantly improved cardiac function indicators, myocardial structure, myocardial enzymes, and mitochondrial function, together with reduced oxidative stress and apoptosis in IR-injured mice. In vitro, MGF significantly increased cell viability, inhibited the release of LDH, reduced oxidative stress and apoptosis, and improved mitochondrial function in both HR and H2O2-injured HL-1 cells. In particular, the GAS6/Axl signaling pathway plays an important role in this process. Additionally, we also demonstrated that GAS6 gene knockout reversed the protective effect of MGF against HR and H2O2-injured cardiomyocytes. The present study confirmed that MGF has protective effects against myocardial IR injury by activating the GAS6/Axl pathway, providing a theoretical basis for MGF as a potential cardioprotective drug in the clinical setting of myocardial IR injury.

Endothelial Dysfunction: Redox Imbalance, NLRP3 Inflammasome, and Inflammatory Responses in Cardiovascular Diseases

Endothelial dysfunction (ED) is characterized by an imbalance between vasodilatory and vasoconstrictive factors, leading to impaired vascular tone, thrombosis, and inflammation. These processes are critical in the development of cardiovascular diseases (CVDs) such as atherosclerosis, hypertension and ischemia/reperfusion injury (IRI). Reduced nitric oxide (NO) production and increased oxidative stress are key contributors to ED. Aging further exacerbates ED through mitochondrial dysfunction and increased oxidative/nitrosative stress, heightening CVD risk. Antioxidant systems like superoxide-dismutase (SOD), glutathione-peroxidase (GPx), and thioredoxin/thioredoxin-reductase (Trx/TXNRD) pathways protect against oxidative stress. However, their reduced activity promotes ED, atherosclerosis, and vulnerability to IRI. Metabolic syndrome, comprising insulin resistance, obesity, and hypertension, is often accompanied by ED. Specifically, hyperglycemia worsens endothelial damage by promoting oxidative stress and inflammation. Obesity leads to chronic inflammation and changes in perivascular adipose tissue, while hypertension is associated with an increase in oxidative stress. The NLRP3 inflammasome plays a significant role in ED, being triggered by factors such as reactive oxygen and nitrogen species, ischemia, and high glucose, which contribute to inflammation, endothelial injury, and exacerbation of IRI. Treatments, such as N-acetyl-L-cysteine, SGLT2 or NLRP3 inhibitors, show promise in improving endothelial function. Yet the complexity of ED suggests that multi-targeted therapies addressing oxidative stress, inflammation, and metabolic disturbances are essential for managing CVDs associated with metabolic syndrome.

A study on the molecular mechanism of cardiac protection of procarboxylpeptidase in MIRI rats based on the NLRP3 signaling pathway

ObjectiveTo investigate the way in which prolylcarboxypeptidase (PRCP) protects against myocardial ischemia-reperfusion injury (MIRI) and the mechanisms that underlie it.MethodA surgical ligation of the coronary artery was adopted to establish a myocardial ischemia-reperfusion model in male SD rats. Thirty-six rats were randomly divided into six groups: Normal group, Sham group, MIRI model group, empty vector (MIRI + EZ.null) group, PRCP overexpression (MIRI + PRCP) group, and nicorandil (MIRI + Nic) group, with 6 rats in each group. The rats received an injection of PRCP's adeno-associated virus 9 (AAV9) through the tail vein 3 weeks prior to the modeling.ResultsCompared with the Normal and Sham groups, the expression levels of NOD-like receptor thermal protein domain-associated protein 3 (NLRP3), Caspase-1, IL-18, IL-1β, and GSDMD in the MIRI group and MIRI + EZ-null group were significantly increased (P < 0.05). Myocardial apoptosis index, myocardial infarction size, ejection fraction, and short axis shortening rate were significantly increased (P < 0.05). At the same time, PRCP and nicorandil therapy could reverse the damage effect caused by MIRI (P < 0.05).ConclusionPRCP can lessen MIRI and protect cardiac function in rats by inhibiting NLRP3/Capase-1/IL-18/IL-1β signaling pathway-mediated cell pyroptosis.

Stachyose ameliorates myocardial ischemia-reperfusion injury by inhibiting cardiomyocyte ferroptosis and macrophage pyroptosis

Myocardial ischemia-reperfusion injury (MIRI) is a complex pathological process that results from the restoration of blood flow to ischemic myocardium, leading to a series of detrimental effects including oxidative stress and inflammation. Stachyose, a naturally occurring oligosaccharide found in traditional Chinese medicinal herbs, has been suggested to possess therapeutic properties against various pathological conditions. However, its impact on MIRI and the underlying mechanisms have not been fully elucidated. In this study, we aimed to investigate the therapeutic effects of stachyose on MIRI and to uncover the molecular mechanisms involved. Using both in vivo and in vitro models of MIRI, we evaluated the effects of stachyose on cardiac function and cell death pathways. Our results indicate that stachyose significantly improves cardiac function and reduces infarct size in MIRI mice. Mechanistically, stachyose modulates the ferroptotic pathway in cardiomyocytes by upregulating the expression of glutathione peroxidase 4 (GPX4) and reducing lipid peroxides and iron levels. Additionally, stachyose inhibits the pyroptotic pathway in macrophages by downregulating the expression of NLRP3, gasdermin D (GSMD-N), and cleaved-caspase-1, leading to decreased levels of proinflammatory cytokines interleukin (IL)-1β and IL-18. This study demonstrates that stachyose exerts a protective effect against MIRI by targeting both ferroptosis and pyroptosis pathways, suggesting its potential as a novel therapeutic agent for the treatment of MIRI. Further research is warranted to explore the detailed mechanisms and therapeutic potential of stachyose in clinical settings.

Diltiazem Hydrochloride Protects Against Myocardial Ischemia/Reperfusion Injury in a BNIP3L/NIX-Mediated Mitophagy Manner

Background

Mitochondrial calcium uptake-induced mitophagy may play an essential role in myocardial ischemia/reperfusion (MI/R) injury. Diltiazem hydrochloride (DIL), a traditional calcium channel blocker, can alleviate MI/R injury by blocking calcium overload. However, whether the protective mechanism of DIL involves mitophagy remains elusive. This study aimed to clarify the underlying molecular mechanism by which DIL ameliorates MI/R injury by downregulating mitophagy in vivo and in vitro.

Methods

Thirty rats were randomized into three groups: the sham, MI/R, and MI/R+DIL (1 mg/kg) groups (n = 10/per group). MI/R injury was induced by ligating the left anterior descending (LAD) artery for 30 min followed by 60 min of reperfusion in vivo. H9C2 cells were selected to establish an oxygen-glucose deprivation/recovery (OGD/R) model to simulate MI/R injury in vitro. The potential mechanism by which DIL alleviates MI/R injury was analyzed based on tissue morphology, mitophagy-related gene transcription, and protein expression.

Results

According to histological and immunohistochemical evaluations, DIL significantly alleviated myocardial damage in vivo. Moreover, DIL significantly increased cell viability, attenuated OGD/R-induced apoptosis, and inhibited mitochondrial autophagy in vitro. Mechanistically, DIL attenuated mitochondrial autophagy through the upregulation of dual-specificity protein phosphatase 1 (DUSP1) and the downregulation of c-Jun N-terminal kinase (JNK) and Bcl2 interacting protein 3-like (BNIP3L, also known as NIX) expression.

Conclusion

Diltiazem hydrochloride protects against myocardial ischemia/reperfusion injury in a BNIP3L/NIX-mediated mitophagy manner in vivo and in vitro.

The PINK1/Parkin signaling pathway-mediated mitophagy: a forgotten protagonist in myocardial ischemia/reperfusion injury

Myocardial ischemia causes extensive damage, further exacerbated by reperfusion, a phenomenon called myocardial ischemia/reperfusion injury (MIRI). Nowadays, the pathological mechanisms of MIRI have received extensive attention. Oxidative stress, multiple programmed cell deaths, inflammation and others are all essential pathological mechanisms contributing to MIRI. Mitochondria are the energy supply centers of cells. Numerous studies have found that abnormal mitochondrial function is an essential "culprit" of MIRI, and mitophagy mediated by the phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1)/Parkin signaling pathway is an integral part of maintaining mitochondrial function. Therefore, exploring the association between the PINK1/Parkin signaling pathway-mediated mitophagy and MIRI is crucial. This review will mainly summarize the crucial role of the PINK1/Parkin signaling pathway-mediated mitophagy in MIR-induced several pathological mechanisms and various potential interventions that affect the PINK1/Parkin signaling pathway-mediated mitophagy, thus ameliorating MIRI.

Potential Roles of IP3 Receptors and Calcium in Programmed Cell Death and Implications in Cardiovascular Diseases

Inositol 1,4,5-trisphosphate receptors (IP3Rs) play a crucial role in maintaining intracellular/cytosolic calcium ion (Ca2+i) homeostasis. The release of Ca2+ from IP3Rs serves as a second messenger and a modulatory factor influencing various intracellular and interorganelle communications during both physiological and pathological processes. Accumulating evidence from in vitro, in vivo, and clinical studies supports the notion that the overactivation of IP3Rs is linked to the pathogenesis of various cardiac conditions. The overactivation of IP3Rs results in the dysregulation of Ca2+ concentration ([Ca2+]) within cytosolic, mitochondrial, and nucleoplasmic cellular compartments. In cardiovascular pathologies, two isoforms of IP3Rs, i.e., IP3R1 and IP3R2, have been identified. Notably, IP3R1 plays a pivotal role in cardiac ischemia and diabetes-induced arrhythmias, while IP3R2 is implicated in sepsis-induced cardiomyopathy and cardiac hypertrophy. Furthermore, IP3Rs have been reported to be involved in various programmed cell death (PCD) pathways, such as apoptosis, pyroptosis, and ferroptosis underscoring their multifaceted roles in cardiac pathophysiology. Based on these findings, it is evident that exploring potential therapeutic avenues becomes crucial. Both genetic ablation and pharmacological intervention using IP3R antagonists have emerged as promising strategies against IP3R-related pathologies suggesting their potential therapeutic potency. This review summarizes the roles of IP3Rs in cardiac physiology and pathology and establishes a foundational understanding with a particular focus on their involvement in the various PCD pathways within the context of cardiovascular diseases.

Free fatty acid receptor 4 in cardiac myocytes ameliorates ischemic cardiomyopathy

Aims

Free fatty acid receptor 4 (Ffar4) is a receptor for long-chain fatty acids that attenuates heart failure driven by increased afterload. Recent findings suggest that Ffar4 prevents ischemic injury in brain, liver, and kidney, and therefore, we hypothesized that Ffar4 would also attenuate cardiac ischemic injury.

Methods and Results

Using a mouse model of ischemia-reperfusion (I/R), we found that mice with systemic deletion of Ffar4 (Ffar4KO) demonstrated impaired recovery of left ventricular systolic function post-I/R with no effect on initial infarct size. To identify potential mechanistic explanations for the cardioprotective effects of Ffar4, we performed bulk RNAseq to compare the transcriptomes from wild-type (WT) and Ffar4KO infarcted myocardium 3-days post-I/R. In the Ffar4KO infarcted myocardium, gene ontology (GO) analyses revealed augmentation of glycosaminoglycan synthesis, neutrophil activation, cadherin binding, extracellular matrix, rho signaling, and oxylipin synthesis, but impaired glycolytic and fatty acid metabolism, cardiac repolarization, and phosphodiesterase activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated impaired AMPK signaling and augmented cellular senescence in the Ffar4KO infarcted myocardium. Interestingly, phosphodiesterase 6c (PDE6c), which degrades cGMP, was the most upregulated gene in the Ffar4KO heart. Further, the soluble guanylyl cyclase stimulator, vericiguat, failed to increase cGMP in Ffar4KO cardiac myocytes, suggesting increased phosphodiesterase activity. Finally, cardiac myocyte-specific overexpression of Ffar4 prevented systolic dysfunction post-I/R, defining a cardioprotective role of Ffa4 in cardiac myocytes.

Conclusions

Our results demonstrate that Ffar4 in cardiac myocytes attenuates systolic dysfunction post-I/R, potentially by attenuating oxidative stress, preserving mitochondrial function, and modulation of cGMP signaling.