Classification of regulatory T cells and their role in myocardial ischemia-reperfusion injury.

Myocardial ischemia-reperfusion injury (MIRI) is closely related to the final infarct size in acute myocardial infarction (AMI). Therefore, reducing MIRI can effectively improve the prognosis of AMI patients. At the same time, the healing process after AMI is closely related to the local inflammatory microenvironment. Regulatory T cells (Tregs) can regulate various physiological and pathological immune inflammatory responses and play an important role in regulating the immune inflammatory response after AMI. However, different subtypes of Tregs have different effects on MIRI, and the same subtype of Tregs may also have different effects at different stages of MIRI. This article systematically reviews the classification and function of Tregs, as well as the role of various subtypes of Tregs in MIRI. A comprehensive understanding of the role of each subtype of Tregs can help design effective methods to control immune reactions, reduce MIRI, and provide new potential therapeutic options for AMI.

PEDF and 34-mer peptide inhibit cardiac microvascular endothelial cell ferroptosis via Nrf2/HO-1 signalling in myocardial ischemia-reperfusion injury.

Myocardial ischemia-reperfusion injury (MIRI) represents a critical pathology in acute myocardial infarction (AMI), which is characterized by high mortality and morbidity. Cardiac microvascular dysfunction contributes to MIRI, potentially culminating in heart failure (HF). Pigment epithelium-derived factor (PEDF), which belongs to the non-inhibitory serpin family, exhibits several physiological effects, including anti-angiogenesis, anti-inflammatory and antioxidant properties. Our study aims to explore the impact of PEDF and its functional peptide 34-mer on both cardiac microvascular perfusion in MIRI rats and human cardiac microvascular endothelial cells (HCMECs) injury under hypoxia reoxygenation (HR). It has been shown that MIRI is accompanied by ferroptosis in HCMECs. Furthermore, we investigated the effect of PEDF and its 34-mer, particularly regarding the Nrf2/HO-1 signalling pathway. Our results demonstrated that PEDF 34-mer significantly ameliorated cardiac microvascular dysfunction following MIRI. Additionally, they exhibited a notable suppression of ferroptosis in HCMECs, and these effects were mediated through activation of Nrf2/HO-1 signalling. These findings highlight the therapeutic potential of PEDF and 34-mer in alleviating microvascular dysfunction and MIRI. By enhancing cardiac microvascular perfusion and mitigating endothelial ferroptosis, PEDF and its derivative peptide represent promising candidates for the treatment of AMI.

Electroacupuncture alleviates myocardial ischemia-reperfusion injury by inhibiting hypothalamic paraventricular nucleus neurons projecting to the rostral ventrolateral medulla.

Accumulating evidence suggests that electroacupuncture (EA) has obvious therapeutic effects and unique advantages in alleviating myocardial ischemia-reperfusion injury (MIRI), while the underlying neuromolecular mechanisms of EA intervention for MIRI have not been fully elucidated. The aim of the study is to investigate the role of the neural pathway of hypothalamic paraventricular nucleus (PVN) neurons projecting to the rostral ventrolateral medulla (RVLM) in the alleviation of MIRI rats by EA preconditioning. MIRI models were established by ligating the left anterior descending coronary artery for 30 min followed by reperfusion for 2 h. Electrocardiogram recording, chemogenetics, enzyme-linked immunosorbent assay, multichannel physiology recording and haematoxylin-eosin and immunofluorescence staining methods were conducted to demonstrate that the firing frequencies of neurons in the PVN and the expression of c-Fos decreased by EA pretreatment. Meanwhile, EA preconditioning significantly reduced the levels of creatine kinase isoenzymes (CK-MB), cardiac troponin I (cTnI) and lactic dehydrogenase (LDH). Virus tracing showed a projection connection between PVN and RVLM. The inhibition of the PVN-RVLM neural pathway could replicate the protective effect of EA pretreatment on MIRI rats. However, the activation of the pathway weakened the effect of EA preconditioning. EA pretreatment alleviated MIRI by regulating PVN neurons projecting to RVLM. This work provides novel evidence of EA pretreatment for alleviating MIRI.

WSB1, as an E3 ligase, restrains myocardial ischemia-reperfusion injury by activating ß-catenin signaling via promoting GSK3ß ubiquitination.

BACKGROUND: Reperfusion is the most effective strategy for myocardial infarct, but induces additional injury. WD repeat and SOCS box containing protein 1 (WSB1) plays a protective role in ischemic cells. This study aims to investigate the effects of WSB1 on myocardial ischemia-reperfusion (IR) injury. METHODS: The myocardial IR was induced by left anterior descending (LAD) ligation for 45 min and subsequent reperfusion. The overexpression of WSB1 was mediated by tail vein injection of AAV9 loaded with WSB1 encoding sequence two weeks before IR surgery. H9c2 myocardial cells underwent oxygen-sugar deprivation/reperfusion (OGD/R) to mimic IR, and transfected with WSB1 overexpression or silencing plasmid to alter the expression of WSB1. RESULTS: WSB1 was found highly expressed in penumbra of myocardial IR rats, and the WSB1 overexpression relieved IR-induced cardio dysfunction, myocardial infarct and pathological damage, and cardiomyocyte death in penumbra. The ectopic expression of WSB1 in H9c2 myocardial cells mitigated OGD/R-caused apoptosis, and silencing of WSB1 exacerbated the apoptosis. In addition, WSB1 activated ß-catenin signaling, which was deactivated under the ischemic condition. The co-immunoprecipitation results revealed that WSB1 mediated ubiquitination and degradation of glycogen synthase kinase 3 beta (GSK3ß) as an E3 ligase in myocardial cells. The effects of WSB1 on myocardial cells under ischemic conditions were abolished by an inhibitor of ß-catenin signaling. CONCLUSION: WSB1 activated ß-catenin pathway by promoting the ubiquitination of GSK3ß, and restrained IR-induced myocardial injury. These findings might provide novel insights for clinical treatment of myocardial ischemic patients.

Piceatannol protects against myocardial ischemia/reperfusion injury by inhibiting ferroptosis via Nrf-2 signaling-mediated iron metabolism.

Myocardial tissue ischemia damages myocardial cells. Although reperfusion is an effective technique to rescue myocardial cell damage, it may also exacerbate myocardial cell damage. Ferroptosis, an iron-dependent cell death, occurs following myocardial ischemia-reperfusion (I/R). Piceatannol (PCT) is a natural stilbene compound with excellent antioxidant properties that protect against I/R injury and exerts protective effects against ferroptosis-induced cardiomyocytes following I/R injury; however, the exact mechanism remains to be elucidated. PURPOSE: This study aims to investigate the protective effect and mechanism of PCT on myocardial ischemia-reperfusion injury. METHODS: An ischemia-reperfusion model was established via ligation of the left anterior descending branch of mice's hearts and hypoxia-reoxygenation (H/R) of cardiomyocytes. RESULTS: During ischemia-reperfusion, Nuclear factor E2-related factor 2 (Nrf-2) expression was downregulated, the left ventricular function was impaired, intracellular iron and lipid peroxidation product levels were elevated, and cardiomyocytes underwent ferroptosis. Furthermore, ferroptosis was enhanced following treatment with an Nrf-2 inhibitor. After PCT treatment, Nrf-2 expression significantly increased, intracellular ferrous ions and lipid peroxidation products significantly reduced, Ferroportin1 (FPN1) expression increased, and transferrin receptor-1 (TfR-1) expression was inhibited. CONCLUSIONS: PCT regulates iron metabolism through Nrf-2 to protect against myocardial cell ferroptosis induced by myocardial I/R injury.

HMGB1-RAGE axis contributes to myocardial ischemia/reperfusion injury via regulation of cardiomyocyte autophagy and apoptosis in diabetic mice.

Patients with acute myocardial infarction complicated with diabetes are more likely to develop myocardial ischemia/reperfusion (I/R) injury (MI/RI) during reperfusion therapy. Both HMGB1 and RAGE play important roles in MI/RI. However, the specific mechanisms of HMGB1 associated with RAGE are not fully clarified in diabetic MI/RI. This study aimed to investigate whether the HMGB1-RAGE axis induces diabetic MI/RI via regulating autophagy and apoptosis. A db/db mouse model of MI/RI was established, where anti-HMGB1 antibody and RAGE inhibitor (FPS-ZM1) were respectively injected after 10 min of reperfusion. The results showed that treatment with anti-HMGB1 significantly reduced the infarct size, serum LDH, and CK-MB level. Similar situations also occurred in mice administrated with FPS-ZM1, though the HMGB1 level was unchanged. Then, we found that treatment with anti-HMGB1 or FPS-ZM1 performed the same effects in suppressing the autophagy and apoptosis, as reflected by the results of lower LAMP2 and LC3B levels, increased Bcl-2 level, reduced BAX and caspase-3 levels. Moreover, the Pink1/Parkin levels were also inhibited at the same time. Collectively, this study indicates that the HMGB1-RAGE axis aggravated diabetic MI/RI via apoptosis and Pink1/Parkin mediated autophagy pathways, and inhibition of HMGB1 or RAGE contributes to alleviating those adverse situations.

Exercise training decreases lactylation and prevents myocardial ischemia-reperfusion injury by inhibiting YTHDF2.

Exercise improves cardiac function and metabolism. Although long-term exercise leads to circulating and micro-environmental metabolic changes, the effect of exercise on protein post-translational lactylation modifications as well as its functional relevance is unclear. Here, we report that lactate can regulate cardiomyocyte changes by improving protein lactylation levels and elevating intracellular N6-methyladenosine RNA-binding protein YTHDF2. The intrinsic disorder region of YTHDF2 but not the RNA m6A-binding activity is indispensable for its regulatory function in influencing cardiomyocyte cell size changes and oxygen glucose deprivation/re-oxygenation (OGD/R)-stimulated apoptosis via upregulating Ras GTPase-activating protein-binding protein 1 (G3BP1). Downregulation of YTHDF2 is required for exercise-induced physiological cardiac hypertrophy. Moreover, myocardial YTHDF2 inhibition alleviated ischemia/reperfusion-induced acute injury and pathological remodeling. Our results here link lactate and lactylation modifications with RNA m6A reader YTHDF2 and highlight the physiological importance of this innovative post-transcriptional intrinsic regulation mechanism of cardiomyocyte responses to exercise. Decreasing lactylation or inhibiting YTHDF2/G3BP1 might represent a promising therapeutic strategy for cardiac diseases.

Identification of a mechanism promoting mitochondrial sterol accumulation during myocardial ischemia-reperfusion: role of TSPO and STAR.

Hypercholesterolemia is a major risk factor for coronary artery diseases and cardiac ischemic events. Cholesterol per se could also have negative effects on the myocardium, independently from hypercholesterolemia. Previously, we reported that myocardial ischemia-reperfusion induces a deleterious build-up of mitochondrial cholesterol and oxysterols, which is potentiated by hypercholesterolemia and prevented by translocator protein (TSPO) ligands. Here, we studied the mechanism by which sterols accumulate in cardiac mitochondria and promote mitochondrial dysfunction. We performed myocardial ischemia-reperfusion in rats to evaluate mitochondrial function, TSPO, and steroidogenic acute regulatory protein (STAR) levels and the related mitochondrial concentrations of sterols. Rats were treated with the cholesterol synthesis inhibitor pravastatin or the TSPO ligand 4'-chlorodiazepam. We used Tspo deleted rats, which were phenotypically characterized. Inhibition of cholesterol synthesis reduced mitochondrial sterol accumulation and protected mitochondria during myocardial ischemia-reperfusion. We found that cardiac mitochondrial sterol accumulation is the consequence of enhanced influx of cholesterol and not of the inhibition of its mitochondrial metabolism during ischemia-reperfusion. Mitochondrial cholesterol accumulation at reperfusion was related to an increase in mitochondrial STAR but not to changes in TSPO levels. 4'-Chlorodiazepam inhibited this mechanism and prevented mitochondrial sterol accumulation and mitochondrial ischemia-reperfusion injury, underlying the close cooperation between STAR and TSPO. Conversely, Tspo deletion, which did not alter cardiac phenotype, abolished the effects of 4'-chlorodiazepam. This study reveals a novel mitochondrial interaction between TSPO and STAR to promote cholesterol and deleterious sterol mitochondrial accumulation during myocardial ischemia-reperfusion. This interaction regulates mitochondrial homeostasis and plays a key role during mitochondrial injury.

Recombinant human placental growth factor-2 in post-infarction left ventricular dysfunction: a randomized, placebo-controlled, preclinical study.

Placental growth factor (PlGF)-2 induces angio- and arteriogenesis in rodents but its therapeutic potential in a clinically representative post-infarction left ventricular (LV) dysfunction model remains unclear. We, therefore, investigated the safety and efficacy of recombinant human (rh)PlGF-2 in the infarcted porcine heart in a randomized, placebo-controlled blinded study. We induced myocardial infarction (MI) in pigs using 75 min mid-LAD balloon occlusion followed by reperfusion. After 4 w, we randomized pigs with marked LV dysfunction (LVEF < 40%) to receive continuous intravenous infusion of 5, 15, 45 µg/kg/day rhPlGF-2 or PBS (CON) for 2 w using osmotic pumps. We evaluated the treatment effect at 8 w using comprehensive MRI and immunohistochemistry and measured myocardial PlGF-2 receptor transcript levels. At 4 w after MI, infarct size was 16-18 ± 4% of LV mass, resulting in significantly impaired systolic function (LVEF 34 ± 4%). In the pilot study (3 pigs/dose), PIGF administration showed sustained dose-dependent increases in plasma concentrations for 14 days without systemic toxicity and was associated with favorable post-infarct remodeling. In the second phase (n = 42), we detected no significant differences at 8 w between CON and PlGF-treated pigs in infarct size, capillary or arteriolar density, global LV function and regional myocardial blood flow at rest or during stress. Molecular analysis showed significant downregulation of the main PlGF-2 receptor, pVEGFR-1, in dysfunctional myocardium. Chronic rhPIGF-2 infusion was safe but failed to induce therapeutic neovascularization and improve global cardiac function after myocardial infarction in pigs. Our data emphasize the critical need for properly designed trials in representative large animal models before translating presumed promising therapies to patients.

Lysophosphatidic acid contributes to myocardial ischemia/reperfusion injury by activating TRPV1 in spinal cord.

Lysophosphatidic acid (LPA) is a bioactive phospholipid that plays a crucial role in cardiovascular diseases. Here, we question whether LPA contributes to myocardial ischemia/reperfusion (I/R) injury by acting on transient receptor potential vanilloid 1 (TRPV1) in spinal cord. By ligating the left coronary artery to establish an in vivo I/R mouse model, we observed a 1.57-fold increase in LPA level in the cerebrospinal fluid (CSF). The I/R-elevated CSF LPA levels were reduced by HA130, an LPA synthesis inhibitor, compared to vehicle treatment (4.74 ± 0.34 vs. 6.46 ± 0.94 µg/mL, p = 0.0014). Myocardial infarct size was reduced by HA130 treatment compared to the vehicle group (26 ± 8% vs. 46 ± 8%, p = 0.0001). To block the interaction of LPA with TRPV1 at the K710 site, we generated a K710N knock-in mouse model. The TRPV1K710N mice were resistant to LPA-induced myocardial injury, showing a smaller infarct size relative to TRPV1WT mice (28 ± 4% vs. 60 ± 7%, p < 0.0001). Additionally, a sequence-specific TRPV1 peptide targeting the K710 region produced similar protective effects against LPA-induced myocardial injury. Blocking the K710 region through K710N mutation or TRPV1 peptide resulted in reduced neuropeptides release and decreased activity of cardiac sensory neurons, leading to a decrease in cardiac norepinephrine concentration and the restoration of intramyocardial pro-survival signaling, namely protein kinase B/extracellular regulated kinase/glycogen synthase kinase-3ß pathway. These findings suggest that the elevation of CSF LPA is strongly associated with myocardial I/R injury. Moreover, inhibiting the interaction of LPA with TRPV1 by blocking the K710 region uncovers a novel strategy for preventing myocardial ischemic injury.

Y4 RNA fragments from cardiosphere-derived cells ameliorate diabetic myocardial ischemia‒reperfusion injury by inhibiting protein kinase C ß-mediated macrophage polarization.

The specific pathophysiological pathways through which diabetes exacerbates myocardial ischemia/reperfusion (I/R) injury remain unclear; however, dysregulation of immune and inflammatory cells, potentially driven by abnormalities in their number and function due to diabetes, may play a significant role. In the present investigation, we simulated myocardial I/R injury by inducing ischemia through ligation of the left anterior descending coronary artery in mice for 40 min, followed by reperfusion for 24 h. Previous studies have indicated that protein kinase Cß (PKCß) is upregulated under hyperglycemic conditions and is implicated in the development of various diabetic complications. The Y4 RNA fragment is identified as the predominant small RNA component present in the extracellular vesicles of cardio sphere-derived cells (CDCs), exhibiting notable anti-inflammatory properties in the contexts of myocardial infarction and cardiac hypertrophy. Our investigation revealed that the administration of Y4 RNA into the ventricular cavity of db/db mice following myocardial I/R injury markedly enhanced cardiac function. Furthermore, Y4 RNA was observed to facilitate M2 macrophage polarization and interleukin-10 secretion through the suppression of PKCß activation. The mechanism by which Y4 RNA affects PKCß by regulating macrophage activation within the inflammatory environment involves the inhibition of ERK1/2 phosphorylation In our study, the role of PKCß in regulating macrophage polarization during myocardial I/R injury was investigated through the use of PKCß knockout mice. Our findings indicate that PKCß plays a crucial role in modulating the inflammatory response associated with macrophage activation in db/db mice experiencing myocardial I/R, with a notable exacerbation of this response observed upon significant upregulation of PKCß expression. In vitro studies further elucidated the protective mechanism by which Y4 RNA modulates the PKCß/ERK1/2 signaling pathway to induce M2 macrophage activation. Overall, our findings suggest that Y4 RNA plays an anti-inflammatory role in diabetic I/R injury, suggesting a novel therapeutic approach for managing myocardial I/R injury in diabetic individuals.

Oral-gut microbial transmission promotes diabetic coronary heart disease.

BACKGROUND: Diabetes is a predominant driver of coronary artery disease worldwide. This study aims to unravel the distinct characteristics of oral and gut microbiota in diabetic coronary heart disease (DCHD). Simultaneously, we aim to establish a causal link between the diabetes-driven oral-gut microbiota axis and increased susceptibility to diabetic myocardial ischemia-reperfusion injury (MIRI). METHODS: We comprehensively investigated the microbial landscape in the oral and gut microbiota in DCHD using a discovery cohort (n = 183) and a validation chohort (n = 68). Systematically obtained oral (tongue-coating) and fecal specimens were subjected to metagenomic sequencing and qPCR analysis, respectively, to holistically characterize the microbial consortia. Next, we induced diabetic MIRI by administering streptozotocin to C57BL/6 mice and subsequently investigated the potential mechanisms of the oral-gut microbiota axis through antibiotic pre-treatment followed by gavage with specific bacterial strains (Fusobacterium nucleatum or fecal microbiota from DCHD patients) to C57BL/6 mice. RESULTS: Specific microbial signatures such as oral Fusobacterium nucleatum and gut Lactobacillus, Eubacterium, and Roseburia faecis, were identified as potential microbial biomarkers in DCHD. We further validated that oral Fusobacterium nucleatum and gut Lactobacillus are increased in DCHD patients, with a positive correlation between the two. Experimental evidence revealed that in hyperglycemic mice, augmented Fusobacterium nucleatum levels in the oral cavity were accompanied by an imbalance in the oral-gut axis, characterized by an increased coexistence of Fusobacterium nucleatum and Lactobacillus, along with elevated cardiac miRNA-21 and a greater extent of myocardial damage indicated by TTC, HE, TUNEL staining, all of which contributed to exacerbated MIRI. CONCLUSION: Our findings not only uncover dysregulation of the oral-gut microbiota axis in diabetes patients but also highlight the pivotal intermediary role of the increased abundance of oral F. nucleatum and gut Lactobacillus in exacerbating MIRI. Targeting the oral-gut microbiota axis emerges as a potent strategy for preventing and treating DCHD. Oral-gut microbial transmission constitutes an intermediate mechanism by which diabetes influences myocardial injury, offering new insights into preventing acute events in diabetic patients with coronary heart disease.

Uncoupling Protein 2 Alleviates Myocardial Ischemia/Reperfusion Injury by Inhibiting Cardiomyocyte Ferroptosis.

INTRODUCTION: Following our recent finding that Ucp2 knockout promotes ferroptosis, we aimed to examine whether UCP2 alleviates myocardial ischemia/reperfusion injury (MI/RI) by inhibiting ferroptosis. METHODS: The left anterior descending coronary arteries of wild-type and Ucp2-/- C57BL/6 mice were ligated for 30 min and reperfused for 2 h to establish an MI/RI model. The effects of UCP2 on ferroptosis and MI/RI were determined by echocardiography, 2,3,5-triphenylttrazolium chloride staining, hematoxylin-eosin staining, Masson's trichrome staining, Sirius red staining, and analysis of myocardial injury markers and ferroptosis indicators. Ferrostatin-1 (Fer-1) and erastin (Era) were used to investigate whether UCP2 alleviated MI/RI by inhibiting ferroptosis and the molecular mechanism. RESULTS: UCP2 was upregulated in the MI/RI model in WT mice. Deletion of Ucp2 exacerbated ferroptosis, altered the expression levels of multiple ferroptosis-related genes, and significantly exacerbated MI/RI. Knockout of Ucp2 promoted ferroptosis induced by Era and inhibited the antiferroptotic effects of Fer-1. Knockout of Ucp2 activated the p53/TfR1 pathway to exacerbate ferroptosis. CONCLUSION: Our results showed that UCP2 inhibited ferroptosis in MI/RI, which might be related to regulation of the p53/TfR1 pathway.

Research Progress on the Mechanism of Lysosome in Myocardial Ischemia-Reperfusion Injury Based on Autophagy.

In recent years, the interaction of intracellular organelles such as mitochondria and lysosomal functions has attracted increasing attention. Recent evidence suggests that mitochondrion-lysosomal contact plays a key role in regulating lysosomal biogenesis and maintaining cellular homeostasis. Myocardial ischemia and reperfusion will lead to corresponding changes in the autophagy flux in cardiomyocytes, and lysosomes are a key link in the process of autophagy, and the fusion of lysosomes and autophagosomes is an essential link in the occurrence of autophagy. Therefore, the function and homeostasis of lysosomes also undergo different changes during myocardial ischemia and reperfusion. Lysosomal-related biological factors and membrane proteins also play different roles. This article will review the mechanism of lysosomes in myocardial ischemia-reperfusion injury and the research progress of lysosomal-related proteins.

TFAP2C inhibits cell autophagy to alleviate myocardial ischemia/reperfusion injury by regulating miR-23a-5p/SFRP5/Wnt5a axis.

Myocardial ischemia/reperfusion (MI/R) injury contributes to severe injury for cardiomyocytes. In this study, we aimed to explore the underlying mechanism of TFAP2C on cell autophagy in MI/R injury. MTT assay measured cell viability. The cells injury was evaluated by commercial kits. IF detected the level of LC3B. Dual luciferase reporter gene assay, ChIP or RIP assay were performed to verify the interactions between crucial molecules. We found that TFAP2C and SFRP5 expression were decreased while miR-23a-5p and Wnt5a increased in AC16 cells in response to H/R condition. H/R induction led to cell injury and induced autophagy, which were reversed by TFAP2C overexpression or 3-MA treatment (an autophagy inhibitor). Mechanistically, TFAP2C suppressed miR-23a expression through binding to miR-23a promoter, and SFRP5 was a target gene of miR-23a-5p. Moreover, miR-23a-5p overexpression or rapamycin reversed the protective impacts of TFAP2C overexpression on cells injury and autophagy upon H/R condition. In conclusion, TFAP2C inhibited autophagy to improve H/R-induced cells injury by mediating miR-23a-5p/SFRP5/Wnt5a axis.

DJ-1 preserves ischemic postconditioning-induced cardioprotection in STZ-induced type 1 diabetic rats: role of PTEN and DJ-1 subcellular translocation.

BACKGROUND: Ischemic postconditioning (IPostC) has been reported as a promising method for protecting against myocardial ischemia-reperfusion (MI/R) injury. Our previous study found that the infarct-limiting effect of IPostC is abolished in the heart of diabetes whose cardiac expression of DJ-1 (also called PARK7, Parkinsonism associated deglycase) is reduced. However, the role and in particular the underlying mechanism of DJ-1 in the loss of sensitivity to IPostC-induced cardioprotection in diabetic hearts remains unclear. METHODS: Streptozotocin-induced type 1 diabetic rats were subjected to MI/R injury by occluding the left anterior descending artery (LAD) and followed by reperfusion. IPostC was induced by three cycles of 10s of reperfusion and ischemia at the onset of reperfusion. AAV9-CMV-DJ-1, AAV9-CMV-C106S-DJ-1 or AAV9-DJ-1 siRNA were injected via tail vein to either over-express or knock-down DJ-1 three weeks before inducing MI/R. RESULTS: Diabetic rats subjected to MI/R exhibited larger infarct area, more severe oxidative injury concomitant with significantly reduced cardiac DJ-1 expression and increased PTEN expression as compared to non-diabetic rats. AAV9-mediated cardiac DJ-1 overexpression, but not the cardiac overexpression of DJ-1 mutant C106S, restored IPostC-induced cardioprotection and this effect was accompanied by increased cytoplasmic DJ-1 translocation toward nuclear and mitochondrial, reduced PTEN expression, and increased Nrf-2/HO-1 transcription. Our further study showed that AAV9-mediated targeted DJ-1 gene knockdown aggravated MI/R injury in diabetic hearts, and this exacerbation of MI/R injury was partially reversed by IPostC in the presence of PTEN inhibition or Nrf-2 activation. CONCLUSIONS: These findings suggest that DJ-1 preserves the cardioprotective effect of IPostC against MI/R injury in diabetic rats through nuclear and mitochondrial DJ-1 translocation and that inhibition of cardiac PTEN and activation of Nrf-2/HO-1 may represent the major downstream mechanisms whereby DJ-1 preserves the cardioprotective effect of IPostC in diabetes.

Insight into the cardioprotective effects of melatonin: shining a spotlight on intercellular Sirt signaling communication.

Cardiovascular diseases (CVDs) are the leading causes of death and illness worldwide. While there have been advancements in the treatment of CVDs using medication and medical procedures, these conventional methods have limited effectiveness in halting the progression of heart diseases to complete heart failure. However, in recent years, the hormone melatonin has shown promise as a protective agent for the heart. Melatonin, which is secreted by the pineal gland and regulates our sleep-wake cycle, plays a role in various biological processes including oxidative stress, mitochondrial function, and cell death. The Sirtuin (Sirt) family of proteins has gained attention for their involvement in many cellular functions related to heart health. It has been well established that melatonin activates the Sirt signaling pathways, leading to several beneficial effects on the heart. These include preserving mitochondrial function, reducing oxidative stress, decreasing inflammation, preventing cell death, and regulating autophagy in cardiac cells. Therefore, melatonin could play crucial roles in ameliorating various cardiovascular pathologies, such as sepsis, drug toxicity-induced myocardial injury, myocardial ischemia-reperfusion injury, hypertension, heart failure, and diabetic cardiomyopathy. These effects may be partly attributed to the modulation of different Sirt family members by melatonin. This review summarizes the existing body of literature highlighting the cardioprotective effects of melatonin, specifically the ones including modulation of Sirt signaling pathways. Also, we discuss the potential use of melatonin-Sirt interactions as a forthcoming therapeutic target for managing and preventing CVDs.

Targeting PDE4B (Phosphodiesterase-4 Subtype B) for Cardioprotection in Acute Myocardial Infarction via Neutrophils and Microcirculation.

BACKGROUND: Timely and complete restoration of blood flow is the most effective intervention for patients with acute myocardial infarction. However, the efficacy is limited by myocardial ischemia-reperfusion (MI/R) injury. PDE4 (phosphodiesterase-4) hydrolyzes intracellular cyclic adenosine monophosphate and it has 4 subtypes A-D. This study aimed to delineate the role of PDE4B (phosphodiesterase-4 subtype B) in MI/R injury. METHODS: Mice were subjected to 30-minute coronary artery ligation, followed by 24-hour reperfusion. Cardiac perfusion was assessed by laser Doppler flow. Vasomotor reactivities were determined in mouse and human coronary (micro-)arteries. RESULTS: Cardiac expression of PDE4B, but not other PDE4 subtypes, was increased in mice following reperfusion. PDE4B was detected primarily in endothelial and myeloid cells of mouse and human hearts. PDE4B deletion strikingly reduced infarct size and improved cardiac function 24-hour or 28-day after MI/R. PDE4B in bone marrow-derived cells promoted MI/R injury and vascular PDE4B further exaggerated this injury. Mechanistically, PDE4B mediated neutrophil-endothelial cell interaction and PKA (protein kinase A)-dependent expression of cell adhesion molecules, neutrophil cardiac infiltration, and release of proinflammatory cytokines. Meanwhile, PDE4B promoted coronary microcirculatory obstruction and vascular permeability in MI/R, without affecting flow restriction-induced thrombosis. PDE4B blockade increased flow-mediated vasodilatation and promoted endothelium-dependent dilatation of coronary arteries in a PKA- and nitric oxide-dependent manner. Furthermore, postischemia administration with piclamilast, a PDE4 pan-inhibitor, improved cardiac microcirculation, suppressed inflammation, and attenuated MI/R injury in mice. Incubation with sera from patients with acute myocardial infarction impaired acetylcholine-induced relaxations in human coronary microarteries, which was abolished by PDE4 inhibition. Similar protection against MI/R-related coronary injury was recapitulated in mice with PDE4B deletion or inhibition, but not with the pure vasodilator, sodium nitroprusside. CONCLUSIONS: PDE4B is critically involved in neutrophil inflammation and microvascular obstruction, leading to MI/R injury. Selective inhibition of PDE4B might protect cardiac function in patients with acute myocardial infarction designated for reperfusion therapy.

cFLIPL alleviates myocardial ischemia-reperfusion injury by regulating pyroptosis.

Alleviating myocardial ischemia-reperfusion injury (MIRI) plays a critical role in the prognosis and improvement of cardiac function following acute myocardial infarction. Pyroptosis is a newly identified form of cell death that has been implicated in the regulation of MIRI. In our study, H9c2 cells and SD rats were transfected using a recombinant adenovirus vector carrying cFLIPL , and the transfection was conducted for 3 days. Subsequently, H9c2 cells were subjected to 4 h of hypoxia followed by 12 h of reoxygenation to simulate an in vitro ischemia-reperfusion model. SD rats underwent 30 min of ischemia followed by 2 h of reperfusion to establish an MIRI model. Our findings revealed a notable decrease in cFLIPL expression in response to ischemia/reperfusion (I/R) and hypoxia/reoxygenation (H/R) injuries. Overexpression of cFLIPL can inhibit pyroptosis, reducing myocardial infarction area in vivo, and enhancing H9c2 cell viability in vitro. I/R and H/R injuries induced the upregulation of ASC, cleaved Caspase 1, NLRP3, GSDMD-N, IL-1ß, and IL-18 proteins, promoting cell apoptosis. Our research indicates that cFLIPL may suppress pyroptosis by strategically binding with Caspase 1, inhibiting the release of inflammatory cytokines and preventing cell membrane rupture. Therefore, cFLIPL could potentially serve as a promising target for alleviating MIRI by suppressing the pyroptotic pathway.

Pachymic acid (PA) inhibits ferroptosis of cardiomyocytes via activation of the AMPK in mice with ischemia/reperfusion-induced myocardial injury.

Pachymic acid (PA) is a lanostane-type triterpenoid with various pharmacological effects. However, little is known about the effect of PA on myocardial infarction (MI) induced by ischemia/reperfusion (I/R). In this study, we aimed to investigate the protective effect of PA and its underlying mechanism. A cellular MI model was established by oxygen-glucose deprivation and reperfusion (OGD/R) treatment in HL-1 cardiomyocytes, and we found that OGD/R treatment decreased cell viability and glutathione peroxide (GSH-Px) activity, increased Fe2+ concentration and lactate dehydrogenase (LDH) activity, promoted malondialdehyde (MDA) and reactive oxygen species (ROS) production, and inhibited the expression of ferroptosis marker proteins SLC7A11 and GPX4 in a time-dependent manner. OGD/R-induced HL-1 cells were pretreated with different concentrations of PA (0, 20, 40, 60 µg/mL) for 24 h, and toxicological experiments showed that 150 µg/mL PA decreased cell viability, while low concentrations of PA had no toxic effect on cells. 20 µg/mL PA reversed the inhibitory effect of OGD/R on cell viability, reduced MDA and ROS production, and Fe2+ accumulation, increased GSH-Px activity and the expression of SLC7A11 and GPX4, and decreased LDH activity, especially at 60 µg/mL PA. Meanwhile, PA promoted the phosphorylation of IRS-1, AKT, and AMPK proteins in a dose-dependent manner. AICAR, an AMPK activator, inhibited ferroptosis, while STO-609, an AMPK inhibitor, largely abolished the effect of PA on OGD/R-induced ferroptosis of HL-1 cells. In addition, PA inhibited ferroptosis and myocardial I/R injury in wild-type mice and AMPK knockout (AMPK-/- ) mice. Collectively, PA inhibited ferroptosis of cardiomyocytes through activating of the AMPK pathway, thereby alleviating myocardial I/R injury in mice.