Reperfusion Injury Research Articles

Saponins as potential novel NLRP3 inflammasome inhibitors for inflammatory disorders.

Nucleotide-binding domain leucine-rich repeat and pyrin domain-containing protein 3 (NLRP3) is a downstream protein from the pattern recognition receptor family that forms the NLRP3 inflammasome. The NLRP3 inflammasome releases caspase-1, IL-1β, and IL-18, contributing to inflammatory responses associated with diabetes mellitus, arthritis, and ischemia-reperfusion injury. Recent studies suggest that specific saponin monomers and extracts from traditional Chinese medicines can inhibit inflammatory responses and related pathways, including the production of inflammatory factors. MCC950 is one of the most influential and specific NLRP3 inhibitors. Comparative molecular docking studies have identified 22 of the 37 saponin components as more robust binders to NLRP3 than MCC950. Dioscin, polyphyllin H, and saikosaponin-a have the highest binding affinities and potential NLRP3 inhibitors, offering a theoretical basis for developing novel anti-inflammatory therapies.

LDHA exacerbates myocardial ischemia-reperfusion injury through inducing NLRP3 lactylation.

Myocardial ischemia-reperfusion (I/R) injury caused by revascularization treatment is the leading cause of cardiac damage aggravation in ischemic heart disease. Increasing evidence has unraveled the crucial role of pyroptosis in myocardial I/R injury. Of note, lactylation has been validated to be participated in modulating pyroptosis. Hence, this study was aimed to elaborate the potential and mechanism of lactylation in myocardial I/R damage. We established the cell model of I/R through inducing hypoxia/reoxygenation (H/R) of H9c2 cells. It was uncovered that H/R stimulation drove cardiomyocyte pyroptosis and upregulated total lactylation level. Further, we demonstrated that promoting lactylation contributed to H/R-evoked pyroptosis, whereas silencing LDHA led to the opposite results. More than that, LDHA was confirmed to facilitate lactylation of NLRP3 at K245 site and increase its protein stability. Our findings indicated that activation of NLRP3 abolished the function of LDHA deficiency in H/R-treated H9c2 cells. In concert with the aforementioned outcomes, knockout of LDHA attenuated the infarct size and myocardial damage in I/R mice and upregulation of NLRP3 counteracted the effects of LDHA knockout on I/R-evoked injury in vivo. To summarize, the current research provided persuasive evidence that LDHA promoted myocardial I/R damage via enhancing NLRP3 lactylation to induce cardiomyocyte pyroptosis.

Inhibition of PCSK9 Protects against Cerebral Ischemia‒Reperfusion Injury via Attenuating Microcirculatory Dysfunction.

Proprotein convertase substilin/kexin type 9 (PCSK9), a pivotal protein regulating lipid metabolism, has been implicated in promoting microthrombotic formation and inflammatory cascades, thereby contributing to cardiovascular ischemia/reperfusion (I/R) injury. However, its involvement in cerebral I/R injury and its potential role in microcirculation protection remain unexplored. In this investigation, we utilized a middle cerebral artery occlusion/reperfusion (MCAO/R) mouse model to simulate ischemic stroke. Different concentrations of evolocumab (1, 5, 10mg/kg, i.v.), a PCSK9 inhibitor, were administered to assess its impact. Immunofluorescence staining was employed to analyze changes in the expression of occludin, claudin-5, thrombocyte, ICAM-1, VCAM-1, and CD45, providing insights into blood-brain barrier integrity, platelet adhesion, and immune cell infiltration. Moreover, the Morris water maze and elevated plus maze were utilized to evaluate neurological and behavioral functions in MCAO/R mice, shedding light on the effects of PCSK9 inhibition. Our findings revealed a surge in plasma PCSK9 levels post-MCAO/R, peaking at 24h post-reperfusion. Evolocumab (10mg/kg) treatment significantly mitigated brain infarction and neurological deficits, evidenced by enhanced locomotor function and reduced post-stroke anxiety. However, it did not ameliorate cognitive impairment following MCAO/R. Additionally, evolocumab administration led to diminished leakage of evans blue solution and upregulated expression of occludin and claudin-5. Thrombocyte, ICAM-1, VCAM-1, and CD45 levels were notably reduced in the penumbral area post-evolocumab treatment. These protective effects are speculated to be mediated through the inhibition of the ERK/NF-κB pathway. The PCSK9 inhibitor evolocumab holds promise as a therapeutic agent during the acute phase of stroke, exerting its beneficial effects by modulating the ERK/NF-κB signaling pathway.

The effect of silymarin on ischemia-reperfusion injury in skeletal muscles of rats silymarin and ischemia-reperfusion injury

Aim: Although the precise process is not entirely elucidated, it is well-known that oxidative stress mediators contribute to ischemia-reperfusion (I/R) injury. The impact of silymarin on I/R injury in many different tissues has been examined. For this purpose, we planned to see the effect of silymarin on muscle tissue in rats subjected to lower extremity I/R injury. Material and Methods: We used 18 male Wistar albino rats weighing 225-275 g. Each of the three groups of rats [Control (C), Ischemia-Reperfusion (I/R), and Silymarin-Ischemia/Reperfusion (S-I/R)] consisted of six rats. Silymarin was administered intraperitoneally 30 minutes before the procedure. (100 mg/kg-1) In Group I/R, the infrarenal abdominal aorta was clamped with a microvascular clamp. The clamp was removed after 120 minutes, and reperfusion was achieved for the next 120 minutes. At the end of the reperfusion period, muscle tissue samples were collected, and Malondialdehyde (MDA), catalase (CAT) enzyme activity levels and histopathological parameters were compared. Results: In the histopathological examination, no degeneration was observed in the muscle fibers in the Group C, while findings of striated muscle damage such as muscle atrophy/hypertrophy, muscle degeneration/congestion, internalization of the muscle nucleus/oval/central nucleus, fragmentation/hyalinization and leukocyte cell infiltration were seen in the Group I/R. In Group S-I/R, muscle atrophy /hypertrophy, internalization of the muscle nucleus/oval/central nucleus, fragmentation/hyalinization, and leukocyte cell infiltration were observed to improve these damaged areas compared to Group I/R. MDA levels in the Group I/R were significantly higher compared to Group C and S-I/R. The activity of the CAT enzyme was much higher in Group I/R compared to Group C. Conclusion: Our study revealed that 100 mg/kg-1 silymarin administered by intraperitoneal injection 30 minutes before ischemia effectively decreased lipid peroxidation, oxidative stress, and the injury caused by I/R in muscle histology in rats.

Multicellular 3D models to study myocardial ischemia–reperfusion injury

Coronary heart disease is a major global health threat, with acute myocardial ischemia–reperfusion injury (IRI) being a major contributor to myocardial damage following an ischemic event. IRI occurs when blood flow to ischemic tissues is restored and exacerbates the cellular damage caused by ischemia/hypoxia. Although animal studies investigating IRI have provided valuable insights, their translation into clinical outcomes has been limited, and translation into medical practice remains cumbersome. Recent advancements in engineered three-dimensional human in vitro models could offer a promising avenue to bridge the “therapeutic valley of death” from bench to bedside, enhancing the understanding of IRI pathology. This review summarizes the current state-of-the-art cardiovascular 3D models, including spheroids, organoids, engineered cardiac microtissues, and organ-on-a-chip systems. We provide an overview of their advantages and limitations in the context of IRI, with a particular emphasis on the crucial roles of cell–cell communication and the multi-omics approaches to enhance our understanding of the pathophysiological processes involved in IRI and its treatment. Finally, we discuss currently available multicellular human 3D models of IRI.

Histopathological Changes in Ovarian Tissues of Rats Underwent Ovarian Ischemia-Reperfusion Injury

This study investigates histopathological changes in ovarian tissues of rats subjected to ischemia-reperfusion (I/R) injury, a condition where restored blood flow causes cellular stress and potential damage. Rats were divided into three groups: control, ischemia, and ischemia-reperfusion. Histological analysis revealed that ischemic ovaries exhibited increased follicular degeneration, atretic follicles, and inflammatory infiltration. The ischemia-reperfusion group showed even more pronounced damage, including disrupted cellular structures and severe vascular congestion. These findings highlight the exacerbated tissue damage caused by reperfusion, underscoring the complex impact of I/R injury on ovarian tissue integrity. Keywords: ovary, ischemia, reperfusion, histology

Early growth response-1, a dynamic conduit in cardiovascular disease

The transcription factor, early growth response-1 (Egr-1) is the product of a prototypic immediate-early gene that plays an integral role in the pathogenesis of multiple cardiovascular diseases. Egr-1 has been linked with atherogenesis, myocardial ischemia-reperfusion injury, cardiac fibrosis and heart failure. Egr-1 expression is triggered by a host of factors including cytokines, hormones, growth factors, hyperglycaemia, biomechanical forces and oxygen deprivation. Egr-1 is a molecular conduit that links changes in the cellular environment with the inducible expression of genes whose products play a causative role in this inflammatory disease. It is rapidly synthesised, undergoes post-translational modification, interacts with a range of cofactors and drives gene expression. Studies in Egr-1 deficient mice, animal models using DNAzymes, RNA interference, oligodeoxynucleotide decoys, antisense oligonucleotides, and new insights provided by technologies such as single cell RNA sequencing, have shaped our understanding of the importance of Egr-1 in the initiation and progression of cardiovascular disease. This article describes Egr-1's role in various cardiovascular settings and discusses potential mechanisms of action. Given the range of conditions linked to Egr-1, this zinc finger protein may serve as a therapeutic target for intervention.

Dynamics of Ischemia/Reperfusion Injury Markers During Normothermic Liver Machine Perfusion

Background. A comprehensive mechanistic assessment of normothermic machine perfusion (NMP) is an essential step toward identifying biomarkers to assess liver viability. Although some studies have evaluated the effect of NMP on inflammation markers, there are other key pathological mechanisms involved in ischemia/reperfusion injury (IRI) that have not yet been evaluated. Methods. Eight human donor livers preserved by NMP were included to analyze IRI during preservation. Concentrations of several biomarkers involved in different biological processes of IRI were measured in the perfusate. Results. Perfusate levels of intercellular adhesion molecule 1, P-selectin, vascular cell adhesion molecule 1, metalloproteinase with thrombospondin motif type 1, member 13, phospholipase A2 group VII, and syndecan-1 progressively increased during NMP. Noteworthy, perfusate lactate levels showed a strong correlation with C-X-C motif chemokine ligand 10 (P = 0.001), intercellular adhesion molecule 1 (P = 0.01), and urokinase plasminogen activator (P = 0.001). Conclusions. Perfusate lactate correlates with the main underlying biological mechanisms occurring in the NMP environment. Moreover, several IRI biomarkers accumulate during NMP, which may limit the extent of the benefits of this technology.

Neuroprotection of Gueichih-Fuling-Wan on cerebral ischemia/ reperfusion injury in streptozotocin-induced hyperglycemic rats via the inhibition of the cellular apoptosis pathway and neuroinflammation

Neuroprotection of Gueichih-Fuling-Wan on cerebral ischemia/ reperfusion injury in streptozotocin-induced hyperglycemic rats via the inhibition of the cellular apoptosis pathway and neuroinflammation

Identification and validation of biomarkers related to mitochondria during ex vivo lung perfusion for lung transplants based on machine learning algorithm.

Ex vivo lung perfusion (EVLP) is a critical strategy to rehabilitate marginal donor lungs, thereby increasing lung transplantation (LTx) rates. Ischemia-reperfusion (I/R) injury inevitably occurs during LTx. Exploring the common mechanisms between EVLP and I/R may unveil new treatment targets to enhance LTx outcomes. We obtained datasets from the public Gene Expression Omnibus (GEO) for EVLP (GSE127055 and GSE127057) and I/R (GSE145989) processes. We performed analysis of differential gene expression (DEGs) and Gene Set Enrichment Analysis (GSEA). Mitochondrial genes were sourced from the MitoCarta 3.0 database. Hub mitochondrial-related DEGs (MitoDEGs) were identified using a combination of protein-protein interaction networks and machine learning methods, which were further validated in cell and mice models of EVLP. GSEA analysis of DEGs following EVLP and I/R revealed significant inhibition of mitochondrial function pathways, encompassing mitochondrial central dogma, mtRNA metabolism, OXPHOS assembly factors, metals and cofactors, and heme synthesis and processing processes. Machine learning algorithms including random forest, LASSO, and XGBoost identified five downregulated genes (MTERF1, ACACA, COX15, OSGEPL1, and COQ9) as hub MitoDEGs for both EVLP and I/R processes. We confirmed the reduced expression of these hub MitoDEGs in endothelial cells during EVLP and observed mitochondrial damage in endothelial cells characterized by swollen morphology and cristae disappearance. Imbalance in mitochondrial homeostasis is a shared pathological process during EVLP and I/R-induced lung injury. The identified hub mitochondrial-related genes (MTERF1, ACACA, COX15, OSGEPL1, and COQ9) suggest promising therapeutic targets for lung injury during LTx. The downregulation of these genes indicates a significant disruption in mitochondrial function. This study provides potential mitochondrial-related therapeutic targets for I/R-induced lung injury and for donor lung repair during EVLP procedure in LTx.

Astilbin improves the therapeutic effects of mesenchymal stem cells in AKI-CKD mice by regulating macrophage polarization through PTGS2-mediated pathway.

Although mesenchymal stem cells (MSCs) have been proven to be appropriate candidates for the treatment of AKI-CKD, their efficacy is limited and variable. Astilbin (AST) had a protective effect on MSCs from oxidative stress via ROS-scavenging, however, whether it can improve MSCs' renoprotection and the underlying mechanism need to be elucidated. AST-pretreated MSCs were administered intravenously into the ischemia-reperfusion injury mice models and the renal function, pathological changes and inflammation. Were evaluated. In addition, DARTS, molecular docking, surface plasma resonance(SPR), dual-luciferase reporter gene assay and the ChIP-PCR were utilized to explore the potential signaling pathways through which AST exert renal protective effects on MSCs. AST-pretreated MSCs markedly improved kidney function, reduced kidney pathological injury and inflammation in AKI and AKI-CKD mice. RNA-seq results showed that PTGS2 related pathway was significantly up-regulated in MSCs after AST pretreatment. DARTS assay, molecular docking and SPR assay revealed that AST could bind with the transcriptional factor of Kruppel-Like Factor 4(KLF4) protein. The promoter of PTGS2 had the binding and transcriptional activation by KLF4. Furthermore, AST pretreatment promoted the secretion of PGE2 in MSCs. And then the westren blot results showed that the protein levels of CD163 and CD206 were upregulated after coculture in AST-pretreated MSCs, indicating that the polarization of RAW264.7 cells towards M2-like macrophages was induced. Knockdown of PTGS2 reversed the ability of AST-pretreated MSCs in converting macrophages to M2 phenotype and reducing their therapeutic effects on AKI-CKD mice. AST pretreatment enhances the efficacy of MSCs on AKI and AKI-CKD mice by inducing of M2-like phenotype polarization in macrophages through the PTGS2-mediated pathway. This approach not only provides a novel strategy to strengthen the capability of MSCs but also helps elucidate the beneficial effects of the Chinese herbal medicine AST.

Inhibition of Sat1 alleviates myocardial ischemia-reperfusion injury through regulation of ferroptosis via MAPK/ERK pathway

IntroductionMyocardial ischemia-reperfusion injury (MIRI) is a prevalent complication in patients with myocardial infarction. The pathological mechanism of MIRI remains elusive. Ferroptosis plays a critical role in MIRI. This study aimed to investigate the role of spermidine/spermine N1-acetyltransferase 1 (Sat1) in MIRI by regulation of ferroptosis.MethodsRats and H9C2 cells were used to perform MIRI model. The extent of myocardial damage and associated pathological changes were evaluated. Protein expression was detected by western blot. Then we observed the mitochondrial morphology and measured cell viability and damage. The levels of lipid peroxide and glutathione were measured, and lipid reactive oxygen species (ROS) was quantified. Differentially expressed genes (DEGs) in MIRI were analyzed. Moreover, to explore the role of Sat1 in MIRI, this study utilized adeno-associated virus 9 and lentiviral transduction to modulate Sat1 expression in rats and H9C2 cells, respectively. The transcription factor that regulates Sat1 expression was predicated. Luciferase reporter gene experiment was conducted to reveal the potential sites of Sox2 binding to Sat1.ResultsThis study revealed that ferroptosis was involved in MIRI. Through bioinformatic analysis, Sat1 was identified as a significant gene in MIRI, which has been reported as an inducer of ferroptosis. Our results showed that Sat1 expression was significantly increased in MIRI. Next, the study showed that inhibition of Sat1 alleviated MIRI by suppressing ferroptosis in vivo and in vitro, and over-expression of Sat1 promoted MIRI via activation of ferroptosis. Furthermore, Sat1 and its interacting genes were enriched in several signaling pathways, including ferroptosis and the MAPK signaling pathway. The results showed that Sat1 regulated MIRI through ferroptosis via MAPK/ERK pathway. Moreover, it is found that Sox2 can suppress Sat1 expression at the transcriptional level. The potential binding site was TAACAAAGGAA.ConclusionIn sum, this study demonstrated Sat1 expression was increased in MIRI, inhibition of Sat1 can alleviate MIRI by regulating ferroptosis via MAPK/ERK pathway, and Sat1 was negatively regulated by Sox2. These findings suggested that Sat1 may serve as a potential therapeutic target for the treatment of MIRI.

Normothermic Machine Perfusion Reconstitutes Porcine Kidney Tissue Metabolism But Induces an Inflammatory Response, Which Is Reduced by Complement C5 Inhibition

Normothermic machine perfusion (NMP) is a clinical strategy to reduce renal ischemia-reperfusion injury (IRI). Optimal NMP should restore metabolism and minimize IRI induced inflammatory responses. Microdialysis was used to evaluate renal metabolism. This study aimed to assess the effect of complement inhibition on NMP induced inflammatory responses. Twenty-two pig kidneys underwent 18 h of static cold storage (SCS) followed by 4 h of NMP using a closed-circuit system. Kidneys were randomized to receive a C5-inhibitor or placebo during SCS and NMP. Perfusion resulted in rapidly stabilized renal flow, low renal resistance, and urine production. During SCS, tissue microdialysate levels of glucose and pyruvate decreased significantly, whereas glycerol increased (p < 0.001). In the first hour of NMP, glucose and pyruvate increased while glycerol decreased (p < 0.001). After 4 h, all metabolites had returned to baseline. Inflammatory markers C3a, soluble C5b-9, TNF, IL-6, IL-1β, IL-8, and IL-10 increased significantly during NMP in perfusate and kidney tissue. C5-inhibition significantly decreased perfusate and urine soluble C5b-9 (p < 0.001; p = 0.002, respectively), and tissue IL-1β (p = 0.049), but did not alter other inflammatory markers. Microdialysis can accurately monitor the effect of NMP on renal metabolism. Closed-circuit NMP induces inflammation, which appeared partly complement-mediated. Targeting additional immune inhibitors should be the next step.

Hydrocortisone improves post-resuscitation myocardial dysfunction by inhibiting the NF-κB pathway.

Myocardial dysfunction is a major cause of early mortality after successful cardiopulmonary resuscitation (CPR) following cardiac arrest (CA). Following the return of spontaneous circulation, myocardial ischemia-reperfusion injury can activate the NF-κB pathway, leading to the transcription of inflammatory genes that impair myocardial function. While clinical studies show hydrocortisone (HC) improves outcomes in CA patients during CPR, its specific role in modulating the NF-κB pathway is unclear. In this study, we established an in vitro model by inducing hypoxia/reoxygenation (H/R) injury in H9C2 cardiomyocytes using Na2S2O4, followed by HC treatment. The results showed that HC treatment of H/R-injured cardiomyocytes promoted proliferation, inhibited apoptosis, and suppressed the NF-κB pathway, thereby reducing IL-6, IL-8, and TNF-α levels. Moreover, inhibition of the NF-κB pathway enhanced the proliferative capacity of H/R cardiomyocytes, decreased apoptosis rates, and reduced IL-6, IL-8, and TNF-α expression levels, with these effects being further amplified by HC treatment. These findings were further supported by in vivo experiments. In conclusion, our study suggests that HC may promote H/R cardiomyocyte proliferation, inhibit apoptosis, and alleviate inflammatory responses by suppressing the NF-κB pathway, providing new evidence to support its potential clinical application in CA management.

Abstract 4140123: Real-time imaging of microvasculature obstruction and the vasculoprotection of nitric-oxide-donor nanoparticles during acute myocardial ischemia/reperfusion injury

Background/Introduction: Microvascular obstruction (MVO), due to damage to the coronary microvasculature, is a key determinant of infarct size, heart failure and poor outcomes following acute myocardial infarction, and there is currently no treatment for preventing MVO. Real-time in vivo imaging of MVO in the beating rodent heart is challenging due to the limited spatial and temporal resolution from movement artifacts. Here, we apply, for the first time, fiber-optic confocal laser endomicroscopy (CLM) for real-time imaging of the microvasculature in a beating murine heart with acute ischemia/reperfusion injury (IRI), and then monitoring the development of MVO. Methods: An in vivo murine acute myocardial IRI model (45 min ligation of left coronary artery (LCA) and 30 min reperfusion) was applied. At 10 min prior to ischaemia, 150 µl Dextran-FITC (150 kDa, 10 mg/ml) was injected retro-orbitally, and then CLM imaging with a flexible miniprobe (ProFlex S-1500 with CellVizio system) was applied to the epicardial surface at multiple sites at 5 min post-injection (baseline), 30 min post-ischemia and 30 min post-reperfusion. A nitric oxide donor(NO) nanoparticle (NONP) was synthesized and IV bolus injected into IRI mice 5min prior to reperfusion to prevent MVO. Results: We confirmed visualization of the macro- and microvasculature at various sites on the epicardial surface of the beating heart. Next, we observed reduced microvasculature blood flow below LCA ligature as evidenced by reduced or even totally absence of FITC within the vessels at 30min post-ischemia. The microvasculature at the non-ischemic myocardium was unaffected. Furthermore, at 30 min post-reperfusion, we visualised patchy areas of reduced FITC signal suggesting MVO, and damaged microvasculature as evidenced by leakage of FITC outside the vessel. Interestingly, NONP treatment preserved the microvascular network and prevented MVO at 30 min post-reperfusion with even greater FITC, suggesting increased microvascular blood flow and penetration into cardiac tissue because of the vasodilatory effect of NO in the ischemic area. Conclusion: With CellVizio CLM system, we have demonstrated the MVO development during IRI, and damage to the microvasculature with leakage of dye from vessels into cardiac interstitium, thereby providing a pre-clinical platform to test novel therapeutic agents for preventing MVO. Importantly, we have shown an effective MVO prevention with NO-donor nanoparticle following IRI in mice.

Abstract Sa1105: The Effect of a Combination of Neuroprotective Medications on Post-Cardiac Arrest Survival

Introduction: Reperfusion injury after cardiac arrest (CA) leads to poor survival and neurological outcomes. We hypothesized that a combination of pharmacologic neuroprotection therapies administered 24-72 hours post-CA [“combination therapy”] that target key steps in reperfusion injury; 1) excitotoxicity (Magnesium, Memantine, Perampanel, Minocycline), 2) mitochondrial dysfunction (Thiamine, Coenzyme Q10), 3) oxidative stress (Vitamin C, Vitamin E), and 4) inflammation (Hydrocortisone), would improve survival. AIMS: We compared survival between subjects with combination therapy and those without. Methods: A retrospective analysis of post-CA patients (01/01/2019 - 06/01/2023) was conducted as part of a quality improvement project. Inclusion: in-hospital CA, age ≥ 18 years, non-COVID, ≥ 5 min CPR, sustained ROSC (≥ 20 min). Exclusion: out-of-hospital CA. Combination therapy was at the discretion of the provider and given in addition to current post-CA standard critical care: targeted temperature management (TTM) (32-36°C), glucose (target 140 mg/dL), PaO2 (target 100 mmHg), PaCO2 (target 40 mmHg), and MAP (target 80 - 100 mmHg). Survival was assessed at hospital discharge. Results: Among 196 subjects, 146 received combination therapy (study group) and 50 did not (control group). Demographic variables (age, race, ethnicity) and intra-cardiac arrest variables (initial rhythm, CPR duration, and hospital site) were not statistically different between groups. Post-CA variables (mean PaCO2, PaO2, and glucose) were not statistically different between groups. MAP was 76 (69, 83) for study group and 65 (46, 72) for control group ( P = <0.001). Lowest temperature in study group was 34.8°C vs. 35.9°C in control group ( P = 0.034). Survival at hospital discharge was 33% for study group and 14% for control group ( P = 0.01). There were no known safety concerns or adverse events. Conclusions: The administration of a combination of neuroprotective medications that target key pathways in reperfusion injury appears to be feasible and safe, and may improve survival beyond current post-CA standard critical care. A future randomized controlled trial that includes the assessment of neurological outcomes is warranted.

Abstract 4138498: Sex Differences in Plasma Acylcarnitines in Patients with STEMI undergoing Primary PCI

Background: Rapid coronary reperfusion using primary PCI is the corner stone therapy for patients presenting with STEMI that restores blood flow and limits infarct size. But paradoxically, the reperfusion process itself can induce additional myocardial injury. Females have increased rates of cardiovascular death compared with males following MI, and it is unclear whether this is related to differences in presentation or reperfusion injury. Given these differences, we aim to better understand the sex differences in the lipidome shift post PCI. METHODS&RESULTS: 126 patients(97 males, 29 females) undergoing PCI for STEMI in a tertiary centre underwent venous blood sampling and semi-targeted Liquid Chromatography Tandem Mass Spectrometry(LC/MS/MS) to determine 291 lipid species. Samples were taken pre-PCI(T0), and 2 hours post PCI(T1) with successful reperfusion. Each lipid class and species were compared between males and females at each time point using statistical analysis, to determine the similarities and differences in plasma lipidome shifts in ACS between sexes. Whilst most lipid classes decrease following reperfusion in STEMI (T0 vs T1), Acylcarnitines increase (20%, adjusted p=0.003) in both sexes. There is a clear sex difference with a greater increase in females (39% increase, adjusted p=0.03), as compared with males (13% increase, adjusted p=0.048). In both sexes this is primarily driven by OctadecanoylCarnitine (C8), which is a medium-chained acylcarnitine. Notably, there was no significant difference in C8 between the sexes in the control group, nor the pre-PCI group(adjusted p=0.48, at T0). At T0, total free fatty acids(FFA) and total phosphatidylinositol were significantly elevated in females compared with males(adjusted p=0.012, p=0.018 respectively). Conclusion: Our analysis suggests there are differences in lipidomics shift between males and females in response to myocardial reperfusion. The higher levels of circulating FFA in ischemic females pre-PCI(T0), followed by a parallel increase of acylcarnitine with reperfusion(T0vsT1), suggest differences between the sexes in myocardial metabolic response to reperfusion injury. C8 has been associated with elevated risk of cardiovascular death in stable CAD, but its clinical impact during reperfusion is still unknown. Detailed understanding of sex specific lipidomics shifts during reperfusion injury will allow us to better understand the mechanistic differences in clinical outcome between males and females.

Abstract 4124277: Resorcimoline, a Novel Free Radical Scavenger, Exhibits Cardioprotective Effects Following Coronary Ischemia-reperfusion Injury

Background: Ischemic heart disease remains the leading cause of death worldwide. Early coronary revascularization is the most important treatment. Recent findings have revealed that reactive oxygen species (ROS) can lead to tissue damage following coronary artery revascularization, known as ischemia-reperfusion injury. In this study, we focused on a novel free radical scavenger, resorcimoline (RML). Last year, we reported the scavenging activity of RML in vitro against multiple ROS, confirmed by the electron spin resonance spectrometry. Hypothesis: Resorcimoline might reduce ROS damage in cardiomyocytes, thereby exerting cardioprotective effects following coronary ischemia-reperfusion injury. Methods: Nine-to-eleven-week-old male Wistar rats were subjected to acute myocardial ischemia induced by ligation of the left anterior descending coronary artery for 30 minutes. Rats received intravenous injections of RML at 6 mg/kg before the ligation release or saline as a control. The heart sections were double-stained at 24-hour reperfusion with Evans blue and triphenyltetrazolium chloride to assess the infarct area. Cardiac function was evaluated at 2-day and 7-day reperfusion with echocardiography. Myocardial fibrosis was assessed at 7-day reperfusion by Masson’s trichrome staining. Primary cultured rat cardiomyocytes were treated with 10 μM angiotensin II for 3.5 hours and then exposed to RML for 30 minutes. Cellular ROS assay kits were used to assess the levels of ROS in the cardiomyocytes. Results: Infarct size in RML-treated animals was significantly smaller than in control animals (41.8±19.4% vs. 60.8±12.9%, p=0.03, Fig. 1A). Apoptotic cells in the border zone were significantly reduced in RML-treated animals (32.0±11.7% vs. 55.1±16.9%, p=0.01, Fig. 1B). Troponin I level in RML-treated animals was significantly lower than in control animals (p=0.04, Fig. 1C). Ejection fraction in RML-treated animals was significantly preserved at 2-day reperfusion and 7-day reperfusion when compared to control animals (p=0.001, p=0.003, Fig. 2A). Myocardial fibrosis area in RML-treated animals was significantly smaller than in control animals (23.9±11.7% vs. 40.6±15.6%, p=0.01, Fig. 2B). RML significantly reduced angiotensin II-induced ROS in cardiomyocytes in a concentration-dependent manner (Fig. 3A,B,C). Conclusion: Resorcimoline exhibits cardioprotective effects following coronary ischemia-reperfusion injury by reducing the infarct size and ROS damage in cardiomyocytes.

STAP2 promotes the progression of renal fibrosis via HSP27.

Renal fibrosis is a key process in the progression from acute kidney injury (AKI) to chronic kidney disease (CKD), while the intricate mechanisms of renal fibrosis remain obscure. While the signal-transducing adaptor protein 2 (STAP2) was well-studied for its notable function in inflammation and immune-related disorders, its specific implication in renal fibrosis remains unclear. This study assessed the mechanism by which STAP2 could promote the progression of renal fibrosis. The expression level of STAP2 in fibrotic human samples, murine fibrosis models, and cellular fibrosis models was measured, respectively. Subsequently, immunoprecipitation (IP), mass spectrometry, and RNA sequencing (RNA-seq) were employed to identify HSP27 as an interacting protein and the PI3K-AKT signaling pathway. STAP2 was thereafter knocked down or overexpressed in both in vivo and in vitro models to assess the expression levels of pathway-related and fibrosis-related proteins. Finally, the important role of STAP2 in the fibrosis process in animal models induced by ischemia-reperfusion injury (IRI) and cisplatin was validated. Functionally, in vivo assays demonstrated that the genetic knockout of STAP2 could remarkably mitigate epithelial-mesenchymal transition (EMT), diminish inflammatory cell infiltration, and reduce collagen deposition in mice with renal fibrosis. Conversely, in vitro assays employing STAP2-overexpressing cell models exacerbated the expression levels of fibrosis markers. The outcomes uncovered a potential mechanism by which STAP2 could modulate renal fibrosis through its impact on the expression level of phosphorylated HSP27, as well as modulating the PI3K/AKT signaling pathway. This comprehensive investigation delineated the noticeable function of STAP2 in the advancement of renal fibrosis, and the outcomes might contribute to the development of targeted therapies concentrated on STAP2 to mitigate renal fibrosis.

Abstract 4129440: Ventricular Stunning Following Direct Current Cardioversion: A Case Report

Background: Ventricular stunning refers to a transient mechanical dysfunction of the myocardium, typically manifesting in response to ischemic insults, reperfusion injury, inflammatory states, or neurohormonal overload. Here, we present an unusual case of ventricular stunning precipitated by direct current electrical cardioversion (DEC). Case Report: A 73-year-old man with a history of heart failure with reduced ejection fraction, paroxysmal atrial fibrillation (AF), coronary artery disease, and chronic kidney disease was admitted to a Veterans Affairs hospital for heart failure exacerbation. His hospitalization was complicated by recurrent episodes of symptomatic AF with ventricular rates in the 120-150’s. This was initially managed with intravenous amiodarone and eventually DEC. He continued to experience symptomatic episodes of AF. Later in the hospitalization a repeat DEC with a single 200 joule shock was performed with restoration of sinus rhythm. Several hours afterwards he was found to be unresponsive and hypotensive. Cool extremities and rising serum lactate raised suspicion for cardiogenic shock resulting in transfer to the intensive care unit where vasopressor and inotropic support were initiated. Echocardiogram revealed a precipitous decrease in left ventricular ejection fraction from 25% to 5%. Serum troponin concentrations were unchanged from prior and ECGs demonstrated rate-controlled AF. Clinical Decision Making: This case highlights an episode of unexpected decrease in cardiac output following an otherwise routine repeat DEC for recurrent AF requiring escalation to mechanical circulatory support. His decompensation worsened, necessitating transfer to the local university center for placement of catheter-based miniaturized ventricular assist device (Impella 5’5). Over the subsequent days, with supportive care, his left ventricular ejection fraction recovered to baseline, and mechanical and inotropic support were withdrawn. Conclusion: Ventricular stunning, leading to cardiogenic shock, is a rare and incompletely understood complication of DEC. It warrants consideration when monitoring patients after cardioversion. Implementing vigilant observation protocols post-DEC to detect ventricular stunning and predisposing risk factors could significantly enhance clinical management strategies.