Dynamic Regulation of Cysteine Oxidation and Phosphorylation in Myocardial Ischemia-Reperfusion Injury

Activation of the AMPK-mTOR Pathway by Astaxanthin Against Cold Ischemia-Reperfusion in Rat Liver

To investigate the protective effect and mechanism of astaxanthin on myocardial injury through activation of AMPK-mTOR pathway. In this study, 32 SPF adult male Wistar rats aged 8 to 10 weeks, weighing 250-300 g were divided into 4 groups (n = 8): sham surgery group (S group), autologous orthotopic liver transplantation group (T group), astaxanthin pretreatment surgery group (Group A) and compound C + astaxanthin pretreatment surgery group (Group C). Group A was given astaxanthin 500 mg/kg, group C received compound C 50 mg/kg + astaxanthin 500 mg/kg once a day for 2 weeks, group S and T received same volume of 0.9% saline. 8 h after portal vein opening, blood samples were collected to determine serum concentrations of TNF-α, IL-6 and HMGB 1 and myocardial injury markers. Myocardial tissue was collected to determine the MDA content, SOD activity and activation of AMPK-mTOR pathway. Compared with the S group, higher serum concentrations of TNF-α, IL-6, HMGB 1, CK-MB, cTnI, and H-FABP in groups T, A, and C, increased MDA content and decreased SOD activity, higher expression of activated Caspase-3 was observed; Compared with the T group, in group A, the serum concentrations of TNF-α, IL-6, and HMGB 1, CB-MB, cTnI, and H-FABP were significantly decreased, with decreased MDA content, increased SOD activity, the reduced expression of activated Caspase-3, elevated P-AMPK/AMPK, and decreased P-mTOR/mTOR. In Conclusion, Astaxanthin protects against liver ischemia-induced myocardial injury in rats mediating by the activation of the AMPK-mTOR pathway.

Involvement of Oxidative Stress and Antioxidants in Modification of Cardiac Dysfunction Due to Ischemia-Reperfusion Injury

Delayed reperfusion of the ischemic heart (I/R) is known to impair the recovery of cardiac function and produce a wide variety of myocardial defects, including ultrastructural damage, metabolic alterations, subcellular Ca2+-handling abnormalities, activation of proteases, and changes in cardiac gene expression. Although I/R injury has been reported to induce the formation of reactive oxygen species (ROS), inflammation, and intracellular Ca2+ overload, the generation of oxidative stress is considered to play a critical role in the development of cardiac dysfunction. Increases in the production of superoxide, hydroxyl radicals, and oxidants, such as hydrogen peroxide and hypochlorous acid, occur in hearts subjected to I/R injury. In fact, mitochondria are a major source of the excessive production of ROS in I/R hearts due to impairment in the electron transport system as well as activation of xanthine oxidase and NADPH oxidase. Nitric oxide synthase, mainly present in the endothelium, is also activated due to I/R injury, leading to the production of nitric oxide, which, upon combination with superoxide radicals, generates nitrosative stress. Alterations in cardiac function, sarcolemma, sarcoplasmic reticulum Ca2+-handling activities, mitochondrial oxidative phosphorylation, and protease activation due to I/R injury are simulated upon exposing the heart to the oxyradical-generating system (xanthine plus xanthine oxidase) or H2O2. On the other hand, the activation of endogenous antioxidants such as superoxide dismutase, catalase, glutathione peroxidase, and the concentration of a transcription factor (Nrf2), which modulates the expression of various endogenous antioxidants, is depressed due to I/R injury in hearts. Furthermore, pretreatment of hearts with antioxidants such as catalase plus superoxide dismutase, N-acetylcysteine, and mercaptopropionylglycerine has been observed to attenuate I/R-induced subcellular Ca2+ handling and changes in Ca2+-regulatory activities; additionally, it has been found to depress protease activation and improve the recovery of cardiac function. These observations indicate that oxidative stress is intimately involved in the pathological effects of I/R injury and different antioxidants attenuate I/R-induced subcellular alterations and improve the recovery of cardiac function. Thus, we are faced with the task of developing safe and effective antioxidants as well as agents for upregulating the expression of endogenous antioxidants for the therapy of I/R injury.

Inhibition of Hsp90 K284 Acetylation Aalleviates Cardiac Injury After Ischemia-Reperfusion Injury

Our objective was to determine the role of acetyl-Hsp90 and its relationship with the NF-κB p65 signaling pathway in CVDs. We investigated the effect of acetyl-Hsp90 on cardiac inflammation and apoptosis after ischemia-reperfusion injury (I/RI). The results showed that the induction of acetyl-Hsp90 occurred in the heart during I/R and in primary cardiomyocytes during oxygen-glucose deprivation/reoxygenation (OGD/R). Moreover, the nonacetylated mutant of Hsp90 (Hsp90-K284R), through the regulation of ATPase activities within its N-terminal domain (NTD), indirectly or directly increases its interaction with NF-κB p65. This led to a reduction in the activation of the NF-κB p65 pathway, thereby attenuating inflammation, apoptosis, and fibrosis, ultimately leading to an improvement in cardiac function. Furthermore, we demonstrated that recombinant human interleukin-37 (rIL-37) exerts a similar cardioprotective effect by reducing acetylation at K284 of Hsp90 after inhibiting the expression of KAT2A.

UHPLC-Q-Orbitrap HRMS and network analysis to explore the mechanisms of QiShenYiQi dripping pill for treating myocardial infarction

This study focused on examining the protection of QiShenYiQi dripping pills (QSYQ) against myocardial infarction (MI) and investigating its potential mechanisms. Ultra high performance liquid chromatography-q exactive-orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) was employed to analyze potential active compounds of QSYQ. The targets of these compounds were predicted using an integrated in silico method and cross-referenced with relevant databases to identify associated pathways. Experimental validation was then conducted to confirm the accuracy of the systems pharmacology findings. In the end, network analysis combined with UHPLC screened 13 potential active compounds and obtained 99 targets for the intersection of potential active compounds and diseases. The enrichment analysis results indicated that the cyclic guanosine monophosphate-protein kinase G (cGMP-PKG) signaling pathway might be the mechanism of action of QSYQ in the treatment of MI. Experimental verification demonstrated that QSYQ could alleviate oxidative stress, promote vasodilation, and activate proteins related to the mitochondrial ATP-sensitive potassium channel (KATP) and nitric oxide (NO)-cGMP-PKG signaling pathway. This study provides insights into both the pathogenic mechanisms underlying MI and the molecular mechanisms through which QSYQ may confer protection. Given the role of PKG in regulating myocardial stiffness, it emerges as a promising therapeutic target for myocardial remodeling. We propose that the NO-cGMP-PKG and mitochondrial KATP pathways may serve as candidate therapeutic targets for the development of new interventions for MI.

Post-translational modifications of pyruvate dehydrogenase complex in cardiovascular disease

Pyruvate dehydrogenase complex (PDC) is a crucial enzyme that connects glycolysis and the tricarboxylic acid (TCA) cycle pathway. It plays an essential role in regulating glucose metabolism for energy production by catalyzing the oxidative decarboxylation of pyruvate to acetyl coenzyme A. Importantly, the activity of PDC is regulated through post-translational modifications (PTMs), phosphorylation, acetylation, and O-GlcNAcylation. These PTMs have significant effects on PDC activity under both physiological and pathophysiological conditions, making them potential targets for metabolism-related diseases. This review specifically focuses on the PTMs of PDC in cardiovascular diseases (CVDs) such as myocardial ischemia/reperfusion injury, diabetic cardiomyopathy, obesity-related cardiomyopathy, heart failure (HF), and vascular diseases. The findings from this review offer theoretical references for the diagnosis, treatment, and prognosis of CVD.

The role of serine/threonine protein kinases in cardiovascular disease and potential therapeutic methods

Protein phosphorylation is an important link in a variety of signaling pathways, and most of the important life processes in cells involve protein phosphorylation. Based on the amino acid residues of phosphorylated proteins, protein kinases can be categorized into the following families: serine/threonine protein kinases, tyrosine-specific protein kinases, histidine-specific protein kinases, tryptophan kinases, and aspartate/glutamyl protein kinases. Of all the protein kinases, most are serine/threonine kinases, where serine/threonine protein kinases are protein kinases that catalyze the phosphorylation of serine or threonine residues on target proteins using ATP as a phosphate donor. The current socially accepted classification of serine/threonine kinases is to divide them into seven major groups: protein kinase A, G, C (AGC), CMGC, Calmodulin-dependent protein kinase (CAMK), Casein kinase (CK1), STE, Tyrosine kinase (TKL) and others. After decades of research, a preliminary understanding of the specific classification and respective functions of serine/threonine kinases has entered a new period of exploration. In this paper, we review the literature of the previous years and introduce the specific signaling pathways and related therapeutic modalities played by each of the small protein kinases in the serine/threonine protein kinase family, respectively, in some common cardiovascular system diseases such as heart failure, myocardial infarction, ischemia-reperfusion injury, and diabetic cardiomyopathy. To a certain extent, the current research results, including molecular mechanisms and therapeutic methods, are fully summarized and a systematic report is made for the prevention and treatment of cardiovascular diseases in the future.

Peptide PDRPS6 attenuates myocardial ischemia injury by improving mitochondrial function

Mitochondrial dynamics play a crucial role in myocardial ischemia-reperfusion (I/R) injury, where an imbalance between fusion and fission processes occurs. However, effective measures to regulate mitochondrial dynamics in this context are currently lacking. Peptide derived from the 40 S ribosomal protein S6 (PDRPS6), a peptide identified via peptidomics, is associated with hypoxic stress. This study aimed to investigate the function and mechanism of action of PDRPS6 in I/R injury. In vivo, PDRPS6 ameliorated myocardial tissue injury and cardiomyocyte apoptosis and decreased cardiac function induced by I/R injury in rats. PDRPS6 supplementation significantly reduced apoptosis in vitro. Mechanistically, PDRPS6 improved mitochondrial function by decreasing reactive oxygen species (ROS) levels, maintaining mitochondrial membrane potential (MMP), and inhibiting mitochondrial fission. Pull-down assay analyses revealed that phosphoglycerate mutase 5 (PGAM5) may be the target of PDRPS6, which can lead to the dephosphorylation of dynamin-related protein1 (Drp1) at ser616 site. Overexpression of PGAM5 partially eliminated the effect of PDRPS6 on improving mitochondrial function. These findings suggest that PDRPS6 supplementation is a novel method for treating myocardial injuries caused by I/R.

CircBAZ1B stimulates myocardial ischemia/reperfusion injury (MI/RI) by modulating miR-1252-5p/ATF3-mediated ferroptosis

Introduction

Circular RNAs (circRNAs) have been implicated in myocardial ischemia (MI)/reperfusion injury (RI), yet their essential roles in MI/RI-induced ferroptosis have not been fully elucidated. Here, we focused on the biological function and regulatory mechanism of circBAZ1B, a circRNA derived from the bromodomain adjacent to the zinc finger domain 1B (BAZ1B) gene, in MI/RI progression.

Material and methods

We used a rat model for MI/RI, assessing myocardial infarct size via electrocardiogram (ECG) and histological staining (hematoxylin and eosin [H&E] and 2,3,5-triphenyltetrazolium chloride [TTC]). Rat cardiomyoblasts (H9c2) were used for in vitro hypoxia-reoxygenation (H/R) cell model construction. Cell viability, apoptosis, lipid reactive oxygen species (ROS) levels and iron content were determined via Cell Counting Kit-8 (CCK-8) and flow cytometric assays. Gene and ferroptosis-related protein expression levels were verified by qRT-PCR and Western blotting. RNA pull-down, RNA immunoprecipitation (RIP), and a dual-luciferase reporter system were utilized for verification of the molecular interactions.

Results

The results showed that MI/RI was accompanied by ferroptosis. We also found that activating transcription factor 3 (ATF3) knockdown promoted myocardial cell viability and inhibited ferroptosis. Notably, activation of ATF3 transcription was demonstrated to upregulate the expression of its downstream target ACSL4. Functional analysis indicated that circBAZ1B promoted ATF3 expression via miR-1252-5p. In vivo experimental data further revealed that circBAZ1B suppressed cardiomyocyte activity and promoted ferroptosis, thereby facilitating MI/RI progression.

Conclusions

The circBAZ1B/miR-1252-5p/ATF3 axis is crucial in MI/RI pathogenesis through ferroptosis regulation, offering a potential therapeutic target. Inhibiting this pathway may alleviate MI/RI effects, suggesting the need for further clinical studies.

Protective effects and mechanisms of N-acetylcysteine on indomethacin-induced intestinal injury in a porcine model

This study aimed to investigate the effect of N-acetylcysteine (NAC) on indomethacin (IDMT)-induced intestinal injury in a piglet model and explore the underlying molecular mechanisms. Piglets were randomly divided into 3 treatment groups: (1) control group; (2) IDMT group; (3) NAC+IDMT group. The results showed that NAC administration significantly increased the average daily gain of piglets, attenuated the intestine hyperemia, and restored normal jejunal morphology. Further studies indicated that NAC administration significantly increased plasma citrulline concentration and jejunal villin expression, but decreased the content of proinflammatory cytokines in plasma and jejunum of IDMT-stimulated piglets. NAC administration selectively decreased the proportion of eosinophils but not neutrophils in plasma. Furthermore, NAC administration significantly increased the activities of superoxide dismutase and catalase in plasma but decreased the concentrations of hydrogen peroxide (plasma) and malondialdehyde (plasma and jejunum), as well as the activity of myeloperoxidase (jejunum) when comparing NAC+IDMT group with IDMT group. Gene Ontology analysis showed that the significantly enriched molecular function term was "ubiquitin-like protein ligase binding" for NAC+IDMT versus IDMT differentially regulated genes. In the biological process category, differentially regulated genes of NAC+IDMT versus IDMT were mainly enriched in immune-related terms. The major enrichments for differentially regulated proteins (DRPs) of NAC+IDMT versus IDMT were terms involved in lipid metabolism and immune response. KEGG pathway enrichment analysis showed that "arginine biosynthesis" was a significant enrichment term for the DRPs of NAC+IDMT versus IDMT. Further studies demonstrated that NAC administration up-regulated argininosuccinate synthase 1 mRNA expression and down-regulated arginase mRNA expression in the jejunum of IDMT-stimulated piglets. Moreover, the content of nitric oxide was restored to a normal level with the reduction of nitric oxide synthase activity. NAC administration ameliorated intestinal injury in IDMT-challenged piglets by enhancing antioxidant and anti-inflammatory functions and modulating arginine metabolism in the small intestine.

LOXL1-AS1 Aggravates Myocardial Ischemia/Reperfusion Injury Through the miR-761/PTEN Axis

BACKGROUND AND OBJECTIVES

Myocardial ischemia and reperfusion injury (MIRI) has high morbidity and mortality worldwide. We aimed to explore the role of long noncoding RNA lysyl oxidase like 1 antisense RNA 1 (LOXL1-AS1) in cardiomyocyte pyroptosis.

METHODS

Hypoxia/reoxygenation (H/R) injury was constructed in human cardiomyocyte (HCM). The level of LOXL1-AS1, miR-761, phosphatase and tensin homolog (PTEN) and pyroptosis-related proteins was monitored by quantitative real-time polymerase chain reaction or western blot. Flow cytometry examined the pyroptosis level. Lactate dehydrogenase (LDH), creatine kinase-MB and cardiac troponin I levels were detected by test kits. Enzyme-linked immunosorbent assay measured the release of inflammatory cytokines. Dual-luciferase assay validated the binding relationship among LOXL1-AS1, miR-761, and PTEN. Finally, ischemia/reperfusion (I/R) animal model was constructed. Hematoxylin and eosin staining assessed morphological changes of myocardial tissue. NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and casepase-1 expression was determined by immunohistochemistry.

RESULTS

After H/R treatment, LOXL1-AS1 and PTEN were highly expressed but miR-761 level was suppressed. LOXL1-AS1 inhibition or miR-761 overexpression increased cell viability, blocked the release of LDH and inflammatory cytokines (interleukin [IL]-1β, IL-18), inhibited pyroptosis level, and downregulated pyroptosis-related proteins (ASC, cleaved caspase-1, gasdermin D-N, NLRP3, IL-1β, and IL-18) levels in HCMs. LOXL1-AS1 sponged miR-761 to up-regulate PTEN. Knockdown of miR-761 reversed the effect of LOXL1-AS1 down regulation on H/R induced HCM pyroptosis. LOXL1-AS1 aggravated the MIRI by regulating miR-761/PTEN axis in vivo.

CONCLUSIONS

LOXL1-AS1 targeted miR-761 to regulate PTEN expression, then enhance cardiomyocyte pyroptosis, providing a new alternative target for the treatment of MIRI.

Modulation of Inula racemosa Hook Extract on Cardioprotection by Ischemic Preconditioning in Hyperlipidaemic Rats

Objectives

Hyperlipidemia (HL) is a major cause of ischemic heart diseases. The size-limiting effect of ischemic preconditioning (IPC), a cardioprotective phenomenon, is reduced in HL, possibly because of the opening of the mitochondrial permeability transition pore (MPTP). The objective of this study is to see what effect pretreatment with Inula racemosa Hook root extract (IrA) had on IPC-mediated cardioprotection on HL Wistar rat hearts. An isolated rat heart was mounted on the Langendorff heart array, and then ischemia reperfusion (I/R) and IPC cycles were performed. Atractyloside (Atr) is an MPTP opener.

Methods

The animals were divided into ten groups, each consisting of six rats (n = 6), to investigate the modulation of I. racemosa Hook extract on cardioprotection by IPC in HL hearts Sham control, I/R Control, IPC control, I/R + HL, I/R + IrA + HL, IPC + HL, IPC + NS + HL, IPC + IrA+ HL, IPC + Atr + oxidative stress, mitochondrial function, integrity, and hemodynamic parameters are evaluated for each group.

Results

The present experimental data show that pretreatment with IrA reduced the LDH, CK-MB, size of myocardial infarction, content of cardiac collagen, and ventricular fibrillation in all groups of HL rat hearts. This pretreatment also reduced the oxidative stress and mitochondrial dysfunction. Inhibition of MPTP opening by Atr diminished the effect of IrA on IPC-mediated cardioprotection in HL rats.

Conclusion

The study findings indicate that pretreatment with IrA e restores IPC-mediated cardioprotection in HL rats by inhibiting the MPTP opening.

Er-xian ameliorates myocardial ischemia-reperfusion injury in rats through RISK pathway involving estrogen receptors

Curculigo orchioides (CUR) and Epimedium (EPI) are traditional Chinese medicines with estrogen-like biological activity, called Xianmao and Xianlingpi (Er-xian) in Chinese. However, whether Er-xian exerts protective effects on myocardial ischemia-reperfusion injury (MIRI) is unknown. This study aimed to investigate the cardioprotective effects of Er-xian preconditioning against MIRI and the underlying mechanisms. CUR or EPI was administered intragastrically to aged female rats as a monotherapy or combination therapy. 2 weeks later, a rat MIRI model was established. Myocardial infarction size, myocardial morphology, cTnT, cell apoptosis rate, intracellular calcium concentration, mitochondrial permeability transition pore (MPTP) opening and reperfusion injury salvage kinase (RISK) signaling pathway molecules were observed after the surgery. To evaluate the mechanisms of Er-xian, estrogen receptors antagonists ICI 182780 and G15 were used. In this study, Er-xian notably alleviated myocardial tissue damage, maintained mitochondrial morphology, reduced infarct size and cardiac markers, and increased sera levels of E2. Moreover, Er-xian inhibited calcium overload and mPTP opening, and decreased cardiomyocyte apoptosis. We found that the dual therapy of CUR and EPI elicited more noticeable results than CUR or EPI monotherapy. The significant protective effects of Er-xian on ischemia-reperfusion myocardium were attributed to the up-regulation of AKT, ERK1/2 and GSK-3β phosphorylation levels. The cardioprotective effects of Er-xian were significantly reduced after estrogen receptor blockade, especially GPER30. These results indicate that Er-xian attenuates MIRI through RISK signaling pathway and estrogen receptors are the critical mediators.

The Role of Pyroptosis and Autophagy in Ischemia Reperfusion Injury

Pyroptosis is a process of programmed cell death mediated by gasdermin (GSDM) found in recent years. In the process of pyroptosis, caspase-1 or caspase-11/4/5 is activated, which cleaves gasdermin D and separates its N-terminal pore-forming domain (PFD). The oligomers of PFD bind to the cell membrane and form macropores on the membrane, resulting in cell swelling and membrane rupture. Increasing evidence indicates that pyroptosis is involved in many diseases, including ischemia reperfusion injury. Autophagy is a highly conserved catabolic process in eukaryotic cells. It plays an important role in the survival and maintenance of cells by degrading organelles, proteins, and macromolecules in the cytoplasm and recycling degradation products. Increasing evidence shows that dysfunctional autophagy participates in many diseases. Recently, autophagy and pyroptosis have been reported to play a vital role in the process of ischemia/reperfusion injury, but the related mechanisms are not completely clear. Therefore, this article reviews the role of autophagy and pyroptosis in ischemia–reperfusion injury and analyzes the related mechanisms to provide a basis for future research.

Protective effects of natural products against myocardial ischemia/reperfusion: Mitochondria-targeted therapeutics

Patients with ischemic heart disease receiving reperfusion therapy still need to face left ventricular remodeling and heart failure after myocardial infarction. Reperfusion itself paradoxically leads to further cardiomyocyte death and systolic dysfunction. Ischemia/reperfusion (I/R) injury can eliminate the benefits of reperfusion therapy in patients and causes secondary myocardial injury. Mitochondrial dysfunction and structural disorder are the basic driving force of I/R injury. We summarized the basic relationship and potential mechanisms of mitochondrial injury in the development of I/R injury. Subsequently, this review summarized the natural products (NPs) that have been proven to targeting mitochondrial therapeutic effects during I/R injury in recent years and related cellular signal transduction pathways. We found that these NPs mainly protected the structural integrity of mitochondria and improve dysfunction, such as reducing mitochondrial division and fusion abnormalities, improving mitochondrial Ca²⁺ overload and inhibiting reactive oxygen species overproduction, thereby playing a role in protecting cardiomyocytes during I/R injury. This data would deepen the understanding of I/R-induced mitochondrial pathological process and suggested that NPs are expected to be transformed into potential therapies targeting mitochondria.