Mitochondrial mechanisms in cerebral Ischemia-Reperfusion Injury: Unravelling the intricacies

Cerebral ischemic stroke is a major contributor to physical impairments and premature death worldwide. The available reperfusion therapies for stroke in the form of mechanical thrombectomy and intravenous thrombolysis increase the risk of cerebral ischemia-reperfusion (I-R) injury due to sudden restoration of blood supply to the ischemic region. The injury is manifested by hemorrhagic transformation, worsening of neurological impairments, cerebral edema, and progression to infarction in surviving patients. A complex network of multiple pathological processes has been known to be involved in the pathogenesis of I-R injury. Primarily, 3 major contributors namely oxidative stress, neuroinflammation, and mitochondrial failure have been well studied in I-R injury. A transcription factor, Nrf2 (Nuclear factor erythroid 2-related factor 2) plays a crucial defensive role in resisting the deleterious effects of I-R injury and potentiating the cellular protective mechanisms. In this review, we delve into the critical function of mitochondria and Nrf2 in the context of cerebral I-R injury. We summarized how oxidative stress, neuroinflammation, and mitochondrial anomaly contribute to the pathophysiology of I-R injury and further elaborated the role of Nrf2 as a pivotal guardian of cellular integrity. The review further highlighted Nrf2 as a putative therapeutic target for mitochondrial dysfunction for cerebral I-R injury management.

Value of ultra-high b-value diffusion-weighted imaging for the evaluation of renal ischemia-reperfusion injury

To explore the feasibility of ultra-high b-value diffusion-weighted imaging (ubDWI) in assessment of renal IRI. Thirty-five rabbits were randomized into a control group (n = 7) and a renal IRI group (n = 28). The rabbits in the renal IRI group underwent left renal artery clamping for 60 min. Rabbits underwent axial ubDWI before and at 1, 12, 24, and 48 h after IRI. Apparent diffusion coefficient (ADCst) were calculated from ubDWI with two b-values (b = 0, 1000 s/mm2). Triexponential fits were applied to calculate the pure diffusion coefficients (D), perfusion-related diffusion coefficient (D⁎), and ultra-high ADC (ADCuh). The interobserver reproducibility were evaluated. The repeated measurement analysis of variance and Spearman correlation analysis was used for statistical analysis. The ADCst, D, and ADCuh values showed good reproducibility. The ADCst, D, and D⁎ values of renal Cortex (CO) and outer medulla (OM) significantly decreased after IRI (all P < 0.05). The ADCuh values significantly increased from pre-IRI to 1 h after IRI (P < 0.05) and significantly declined at 24 h and 48 h after IRI (all P < 0.05). ADCuh was strongly positively correlated with AQP-1 in the renal CO and OM (ρ = 0.643, P < 0.001; ρ = 0.662, P < 0.001, respectively). ubDWI can be used to non-invasively evaluate early renal IRI, ADCuh may be adopted to reflect AQP-1 expression.

Therapeutic potential of mitochondrial transplantation in modulating immune responses post-cardiac arrest: a narrative review

BACKGROUND

Mitochondrial transplantation (MTx) has emerged as a novel therapeutic strategy, particularly effective in diseases characterized by mitochondrial dysfunction. This review synthesizes current knowledge on MTx, focusing on its role in modulating immune responses and explores its potential in treating post-cardiac arrest syndrome (PCAS).

METHODS

We conducted a comprehensive narrative review of animal and human studies that have investigated the effects of MTx in the context of immunomodulation. This included a review of the immune responses following critical condition such as ischemia reperfusion injury, the impact of MTx on these responses, and the therapeutic potential of MTx in various conditions.

RESULTS

Recent studies indicate that MTx can modulate complex immune responses and reduce ischemia-reperfusion injury post-CA, suggesting MTx as a novel, potentially more effective approach. The review highlights the role of MTx in immune modulation, its potential synergistic effects with existing treatments such as therapeutic hypothermia, and the need for further research to optimize its application in PCAS. The safety and efficacy of autologous versus allogeneic MTx, particularly in the context of immune reactions, are critical areas for future investigation.

CONCLUSION

MTx represents a promising frontier in the treatment of PCAS, offering a novel approach to modulate immune responses and restore cellular energetics. Future research should focus on long-term effects, combination therapies, and personalized medicine approaches to fully harness the potential of MTx in improving patient outcomes in PCAS.

Protective role of kallistatin in oxygen-glucose deprivation and reoxygenation in human umbilical vein endothelial cells

OBJECTIVE

Ischemia-reperfusion (IR) injury is implicated in various clinical diseases. Kallistatin attenuates oxidative stress, and its deficiency has been associated with poor neurological outcomes after cardiac arrest. The present study investigated the antioxidant mechanism through which kallistatin prevents IR injury.

METHODS

Human umbilical vein endothelial cells (HUVECs) were transfected with small interfering RNA (siRNA) targeting the human kallistatin gene (SERPINA4). Following SERPINA4 knockdown, the level of kallistatin expression was measured. To induce IR injury, HUVECs were exposed to 24 h of oxygen-glucose deprivation and reoxygenation (OGD/R). To evaluate the effect of SERPINA4 knockdown on OGD/R, cell viability and the concentration of kallistatin, endothelial nitric oxide synthase (eNOS) and total NO were measured.

RESULTS

SERPINA4 siRNA transfection suppressed the expression of kallistatin in HUVECs. Exposure to OGD/R reduced cell viability, and this effect was more pronounced in SERPINA4 knockdown cells compared with controls. SERPINA4 knockdown significantly reduced kallistatin concentration regardless of OGD/R, with a more pronounced effect observed without OGD/R. Furthermore, SERPINA4 knockdown significantly decreased eNOS concentrations induced by OGD/R (P<0.01) but did not significantly affect the change in total NO concentration (P=0.728).

CONCLUSION

The knockdown of SERPINA4 resulted in increased vulnerability of HUVECs to OGD/R and significantly affected the change in eNOS level induced by OGD/R. These findings suggest that the protective effect of kallistatin against IR injury may contribute to its eNOS-promoting effect.

Role of APE1/Ref-1 in hydrogen peroxide-induced apoptosis in human renal HK-2 cells

BACKGROUND

Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a multipotent protein that plays essential roles in cellular responses to oxidative stress.

METHODS

To examine the role of APE1/Ref-1 in ischemia-reperfusion (I/R) injuries and hydrogen peroxide (H2O2)-induced renal tubular apoptosis, we studied male C57BL6 mice and human proximal tubular epithelial (HK-2) cells treated with H2O2 at different concentrations. The colocalization of APE1/Ref-1 in the proximal tubule, distal tubule, thick ascending limb, and collecting duct was observed with confocal microscopy. The overexpression of APE1/Ref-1 with knockdown cell lines using an APE1/Ref-1-specific DNA or small interfering RNA (siRNA) was used for the apoptosis assay. The promotor activity of nuclear factor kappa B (NF-κB) was assessed and electrophoretic mobility shift assay was conducted.

RESULTS

APE1/Ref-1 was predominantly localized to the renal tubule nucleus. In renal I/R injuries, the levels of APE1/Ref-1 protein were increased compared with those in kidneys subjected to sham operations. The overexpression of APE1/Ref-1 in HK-2 cells enhanced the Bax/Bcl-2 ratio as a marker of apoptosis. Conversely, the suppression of APE1/Ref-1 expression by siRNA in 1-mM H2O2-treated HK-2 cells decreased the Bax/Bcl-2 ratio, the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, p38, c-Jun N-terminal kinase (JNK) 1/2, and NF-κB. In HK-2 cells, the promoter activity of NF-κB increased following H2O2 exposure, and this effect was further enhanced by APE1/Ref-1 transfection.

CONCLUSION

The inhibition of APE1/Ref-1 with siRNA attenuated H2O2-induced apoptosis through the modulation of mitogen-activated protein kinase pathways mediated by ERK, JNK, and p38 and the nuclear activation of NF-κB and proapoptotic factors.

Effect of serum from patients with ST-segment elevation myocardial infarction on endothelial cells

INTRODUCTION AND OBJECTIVES

Clinical and experimental studies have shown that, in patients with reperfused ST-segment elevation myocardial infarction (STEMI), abnormalities in the endothelial monolayer are initiated during ischemia but rapidly intensify upon restoration of blood perfusion to the ischemic area. We aimed to evaluate the effect of serum isolated after revascularization from STEMI patients on the degree of endothelial permeability in vitro, by promoting endothelial cell apoptosis and necrosis in vitro. We also investigated the association between the percentage of serum-induced endothelial cell apoptosis or necrosis in vitro and the extent of cardiovascular magnetic resonance (CMR)-derived parameters of reperfusion injury (edema, hemorrhage, and microvascular obstruction).

METHODS

Human coronary artery endothelial cells were incubated with serum isolated 24hours after revascularization from 43 STEMI patients who underwent CMR and 14 control participants. We assessed the effect of STEMI serum on activation of apoptosis and necrosis, as well as on the permeability and structure of the endothelial monolayer.

RESULTS

Serum from STEMI patients increased apoptosis (P <.01) and necrosis (P <.05) in human coronary artery endothelial cells and caused increased permeability of the endothelial monolayer in vitro (P <.01), due to enlarged intercellular spaces (P <.05 vs control in all cases). Higher serum-induced necrosis was associated with greater endothelial permeability in vitro (P <.05) and with more extensive CMR-derived indices of reperfusion injury and infarct size.

CONCLUSIONS

Postreperfusion serum activates necrosis and apoptosis in endothelial cells and increases the degree of endothelial permeability in vitro. The more potent the necrosis-triggering effect of serum, the more deleterious the consequences in terms of the resulting cardiac structure.

Protective Effects of Hydrogen Gas Inhalation for Hindlimb Ischaemia-Reperfusion Injury in a Mouse Model

OBJECTIVE

Ischaemia-reperfusion (I/R) injury is a severe post-operative complication that triggers an inflammatory response and causes severe damage. Hydrogen gas has anti-oxidant and anti-apoptotic properties and has been shown to be safe in humans. The study aimed to investigate whether hydrogen gas protects against skeletal muscle I/R injury.

METHODS

Experimental basic research using mice. A total of 160 eight to 10 week old albino laboratory bred strain of house mice (25.8 ± 0.68 g) were used in this study. The mice were cable tied to the hindlimb under anaesthesia and then placed in an anaesthesia box filled with air and 2% isoflurane (control group); 80 mice were additionally subjected to 1.3% hydrogen gas in this mix (hydrogen group). After two hours, the cable ties were removed to initiate reperfusion, and hydrogen inhalation lasted for six hours in the hydrogen group. After six hours, the mice were taken out of the box and kept in cages under standard conditions until time for observation at 16 different time points after reperfusion: zero, two, four, six, eight, and 10 hours and one, two, three, four, five, six, seven, 14, 21, and 28 days. Five mice were sacrificed using excess anaesthesia at each time point, and the bilateral hindlimb tissues were harvested. The inflammatory effects of the I/R injury were assessed by evaluating serum interleukin-6 concentrations using enzyme linked immunosorbent assay, as well as histological and immunohistochemical analyses. Untreated mice with I/R injury were used as controls.

RESULTS

Hydrogen gas showed protective effects associated with a reduction in inflammatory cell infiltration (neutrophils, macrophages, and lymphocytes), a reduced area of damaged muscle, maintenance of normal muscle cells, and replacement of damaged muscle cells with neoplastic myocytes.

CONCLUSION

Inhalation of hydrogen gas had a protective effect against hindlimb I/R injury in mice, in part by reducing inflammatory cell infiltration and in part by preserving normal muscle cells.

The protective effects of gallic acid and SGK1 inhibitor on cardiac damage and genes involved in Ca2+ homeostasis in an isolated heart model of ischemia/reperfusion injury in rat

Serum and glucocorticoid-induced kinase 1 (SGK1) is an enzyme that may play a vital role in myocardial ischemia/reperfusion (I/R) injury. This enzyme may affect sarcoplasmic reticulum Ca2+ ATPase (SERCA2), ryanodine receptor (RyR2) and sodium/calcium exchanger (NCX1) during myocardial ischemia/reperfusion injury. The objective of this investigation was to analyze the effects of the combination of GSK650394 (SGK1 inhibitor) and gallic acid on the calcium ions regulation, inflammation, and cardiac dysfunction resulting from ischemia/reperfusion (I/R) injury in the heart. Sixty male Wistar rats were randomly divided into six groups, pretreated with gallic acid or vehicle for 10 days. Then the heart was isolated and exposed to I/R. In the SGK1 inhibitor groups, GSK650394 was infused 5 min before ischemia induction. After that, Ca2+ homeostasis, inflammatory factors, cardiac function, antioxidant activity, and myocardial damage were evaluated. The findings suggested that the use of two drugs in combination therapy produced more significant improvements in left ventricular end diastolic pressure, left ventricular systolic pressure, RR-interval, ST-elevation, inflammation factors, and antioxidant enzymes activity as compared to the use of each drug. Despite this, there was a significant decrease observed in heart marker enzymes (including lactate dehydrogenase (LDH), troponin-I (cTn-I), creatine kinase-MB (CK-MB) and creatine phosphokinase (CPK) when compared to the ischemic group. Additionally, the expression of RyR2, NCX1, and SERCA2 genes showed a noteworthy increase as compared to the ischemic group. The findings of this study propose that using both of these agents on myocardial I/R injury could have superior advantages compared to using only one of them.

Standardized Pre-clinical Surgical Animal Model Protocol to Investigate the Cellular and Molecular Mechanisms of Ischemic Flap Healing

BACKGROUND

Some of the most complex surgical interventions to treat trauma and cancer include the use of locoregional pedicled and free autologous tissue transfer flaps. While the techniques used for these reconstructive surgery procedures have improved over time, flap complications and even failure remain a significant clinical challenge. Animal models are useful in studying the pathophysiology of ischemic flaps, but when repeatability is a primary focus of a study, conventional in-vivo designs, where one randomized subset of animals serves as a treatment group while a second subset serves as a control, are at a disadvantage instigated by greater subject-to-subject variability. Our goal was to provide a step-by-step methodological protocol for creating an alternative standardized, more economical, and transferable pre-clinical animal research model of excisional full-thickness wound healing following a simulated autologous tissue transfer which includes the primary ischemia, reperfusion, and secondary ischemia events with the latter mimicking flap salvage procedure.

RESULTS

Unlike in the most frequently used classical unilateral McFarlane's caudally based dorsal random pattern skin flap model, in the herein described bilateral epigastric fasciocutaneous advancement flap (BEFAF) model, one flap heals under normal and a contralateral flap-under perturbed conditions or both flaps heal under conditions that vary by one within-subjects factor. We discuss the advantages and limitations of the proposed experimental approach and, as a part of model validation, provide the examples of its use in laboratory rat (Rattus norvegicus) axial pattern flap healing studies.

CONCLUSIONS

This technically challenging but feasible reconstructive surgery model eliminates inter-subject variability, while concomitantly minimizing the number of animals needed to achieve adequate statistical power. BEFAFs may be used to investigate the spatiotemporal cellular and molecular responses to complex tissue injury, interventions simulating clinically relevant flap complications (e.g., vascular thrombosis) as well as prophylactic, therapeutic or surgical treatment (e.g., flap delay) strategies in the presence or absence of confounding risk factors (e.g., substance abuse, irradiation, diabetes) or favorable wound-healing promoting activities (e.g., exercise). Detailed visual instructions in BEFAF protocol may serve as an aid for teaching medical or academic researchers basic vascular microsurgery techniques that focus on precision, tremor management and magnification.

Levofloxacin alleviates blood-brain barrier disruption following cerebral ischemia and reperfusion via directly inhibiting A-FABP

Reperfusion therapy is currently the most effective treatment for acute ischemic stroke, but often results in secondary brain injury. Adipocyte fatty acid-binding protein (A-FABP, FABP4, or aP2) was shown to critically mediate cerebral ischemia/reperfusion (I/R) injury by exacerbating blood-brain barrier (BBB) disruption. However, no A-FABP inhibitors have been approved for clinical use due to safety issues. Here, we identified the therapeutic effect of levofloxacin, a widely used antibiotic displaying A-FABP inhibitory activity in vitro, on cerebral I/R injury and determined its target specificity and action mechanism in vivo. Using molecular docking and site-directed mutagenesis, we showed that levofloxacin inhibited A-FABP activity through interacting with the amino acid residue Asp76, Gln95, Arg126 of A-FABP. Accordingly, levofloxacin significantly inhibited A-FABP-induced JNK phosphorylation and expressions of proinflammatory factors and matrix metalloproteinase 9 (MMP-9) in mouse primary macrophages. In wild-type mice with transient middle cerebral artery occlusion, levofloxacin substantially mitigated BBB disruption and neuroinflammation, leading to reduced cerebral infarction, alleviated neurological outcomes, and improved survival. Mechanistically, levofloxacin decreased MMP-9 expression and activity, and thus reduced degradation of extracellular matrix and endothelial tight junction proteins. Importantly, the BBB- and neuro-protective effects of levofloxacin were abolished in A-FABP or MMP-9 knockout mice, suggesting that the therapeutic effects of levofloxacin highly depended on specific targeting of the A-FABP-MMP-9 axis. Overall, our study demonstrates that levofloxacin alleviates A-FABP-induced BBB disruption and neural tissue injury following cerebral I/R, and unveils its therapeutic potential for the treatment of ischemic stroke.

Protective effects of 4-methylumbelliferone on myocardial ischemia/reperfusion injury in rats through inhibition of oxidative stress and downregulation of TLR4/NF-κB/NLRP3 signaling pathway

Myocardial ischemia-reperfusion injury (MI/R) has been found to be one of the important risk factors for global cardiac mortality and morbidity. The study was conducted to inquire into the protective effect of 4-methylumbilliferon (4-MU) against MI/R in rats and clarify its potential underlying mechanism. Animals were divided into four groups (n = 15) including sham, MI/R, MI/R + vehicle, and MI/R + 4-MU. MI/R was established in Wistar rats by occluding the left anterior descending (LAD) coronary artery for 30 min. 4-MU (25 mg/kg) was injected intraperitoneally before the induction of reperfusion. Cardiac function, fibrosis, oxidant/antioxidant markers, and inflammatory cytokines were evaluated using echocardiography, ELISA, and Western blot assay. As a result of MI/R induction, a decrease in left ventricular contractile function occurred along with increased cardiac fibrosis and tissue damage. The serum levels of TNF-α, IL-1β, and IL-18 increased, while IL-10 decreased. Oxidant/antioxidant changes were evident with increased MDA levels and decreased GSH, SOD, and CAT in the MI/R group. Furthermore, the protein levels of TLR4, NF-κB, and NLRP3 were significantly increased in the heart tissue of MI/R group. Treatment with 4-MU significantly prevented the reduction of cardiac contractile function and its pathological changes as a result of MI/R by inhibiting the increase of serum inflammatory factors and improving the oxidant/antioxidant balance probably through the TLR4/NF-κB/NLRP3 axis. The results of a current study showed that 4-MU had a potential ability to attenuate the cardiac injury by reducing oxidative stress and inflammation in a TLR4/NF-κB/NLRP3-dependent mechanism.

Anti-smoking drugs cytisine and varenicline reduce cardiac reperfusion injury in rat model of myocardial ischemia

Evidence to date indicates that activation of nicotinic acetylcholine receptors (nAChRs) can reduce cardiac injury from ischemia and subsequent reperfusion. The use of nAChR agonists in various animal models leads to a reduction in reperfusion injury. Earlier this effect was shown for the agonists of α7 nAChR subtype. In this work, we demonstrated the expression of mRNA encoding α4, α6 and β2 nAChR subunits in the left ventricle of rat heart. In a rat model of myocardial ischemia, we studied the effect of α4β2 nAChR agonists cytisine and varenicline, medicines used for the treatment of nicotine addiction, and found them to significantly reduce myocardium ischemia-reperfusion injury, varenicline manifesting a higher protection. Dihydro-β-erythroidine, antagonist of α4β2 nAChR, as well as methyllycaconitine, antagonist of α7 and α6β2-containing nAChR, prevented protective effect of varenicline. This together with the presence of α4, α6 and β2 subunit mRNA in the left ventricule of rat heart raises the possibility that the varenicline effect is mediated by α4β2 as well as by α7 and/or α6β2-containing receptors. Our results point to a new way for the use of cytisine and varenicline as cardioprotective agents.

Simvastatin-Loaded Nanoniosome Protects H9c2 Cells from Oxygen-Glucose Deprivation/ Reperfusion Injury by Downregulating Inflammation

Background

Simvastatin (SIM) has anti-inflammatory and antioxidant properties against cardiac ischemia/reperfusion injury (I/RI). However, it suffers from low bioavailability and a short half-life. Nanoniosomes are novel drug delivery systems that may increase SIM effectiveness. The present research evaluates the impact of SIM-loaded nanoniosomes on the oxygen-glucose deprivation/reperfusion (OGD/R) injury model of H9c2 cells.

Methods

Cells were seeded based on five groups: (1) control; (2) OGD/R; (3) OGD/R receiving SIM; (4) OGD/R receiving nanoniosomes; and (5) OGD/R receiving SIM loaded nanoniosomes. OGD/R injury of the H9c2 cells was treated with SIM or SIM loaded nanoniosomes. Cell viability, two inflammatory factors, necroptosis factors, along with HMGB1 and Nrf2 gene expressions were assessed.

Results

The cells treated with SIM loaded nanoniosomes showed a significant elevation in the cell viability and a reduction in HMGB1, Nrf2, TNF-α, IL-1β, RIPK1, and ROCK1 expression levels compared to the OGD/R and SIM groups.

Conclusion

Based on our findings, nanoniosomes could safely serve as a drug delivery system to counterbalance the disadvantages of SIM, resulting in improved aqueous solubility and stability.

Effects of coenzyme Q10 supplementation on oxidative stress biomarkers following reperfusion in STEMI patients undergoing primary percutaneous coronary intervention

Introduction

It is well-established that oxidative stress is deeply involved in myocardial ischemia-reperfusion injury. Considering the potent antioxidant properties of coenzyme Q10 (CoQ10), we aimed to assess whether CoQ10 supplementation could exert beneficial effects on plasma levels of oxidative stress biomarkers in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPIC).

Methods

Seventy patients with the first attack of STEMI, eligible for PPCI were randomly assigned to receive either standard treatments plus CoQ10 (400 mg before PPCI and 200 mg twice daily for three days after PPCI) or standard treatments plus placebo. Plasma levels of oxidative stress biomarkers, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), total antioxidant capacity (TAC), and malondialdehyde (MDA) were measured at 6, 24, and 72 hours after completion of PPCI.

Results

The changes in plasma levels of the studied biomarkers at 6 and 24 hours after PPCI were similar in the both groups (P values>0.05). This is while at 72 hours, the CoQ10- treated group exhibited significantly higher plasma levels of SOD (P value<0.001), CAT (P value=0.001), and TAC (P value<0.001), along with a lower plasma level of MDA (P value=0.002) compared to the placebo-treated group. The plasma activity of GPX showed no significant difference between the groups at all the study time points (P values>0.05).

Conclusion

This study showed that CoQ10 has the potential to modulate the balance between antioxidant and oxidant biomarkers after reperfusion therapy. Our results suggest that CoQ10, through its antioxidant capacity, may help reduce the reperfusion injury in ischemic myocardium.

Evaluation of renal ischemia-reperfusion injury using CEUS in mice

BACKGROUND

Renal ischemia-reperfusion injury (IRI) frequently occurs clinically. We investigated the value of contrast-enhanced ultrasonography (CEUS) in the evaluation of renal IRI levels in mice.

METHODS

Thirty-six healthy adult male C57BL/6 mice (20-22 g) were randomly divided into the sham, 10 min, 20 min, 30 min, 40 min, and 50 min groups based on the time of renal warm ischemia by blocking the left renal pedicle, approved by the Institutional Animal Ethics Committee. Time-intensity curve (TIC)-derived parameters such as peak enhancement (PE) and wash-in perfusion index (WiPI) were produced using CEUS at 1 h and 24 h after IRI. The severity of kidney injury was detected by the renal tubular necrosis rate which was analyzed by hematoxylin and eosin staining at 24 h after IRI. The Spearman correlation coefficient was used to describe the correlations between PE and WiPI values and the renal tubular necrosis rate.

RESULTS

The PE and WiPI values decreased after IRI in the groups with a warm ischemia time ≥ 20 min. The renal tubular necrosis rate was significantly correlated with the PE value at 1 h (ρ = -0.802) and 24 h (ρ = -0.861) after IRI and the WiPI value at 1 h (ρ = -0.814) and 24 h (ρ = -0.853) after IRI (all p < 0.001).

CONCLUSION

TIC-derived parameters, including PE and WiPI values, can be used to evaluate the severity of renal IRI in mice. CEUS is a safe and effective technology for the detection of renal IRI.

RELEVANCE STATEMENT

CEUS can evaluate the severity of renal ischemia-reperfusion injury by peak enhancement and wash-in perfusion index values selected from various time-intensity curve-derived parameters.

KEY POINTS

• Contrast-enhanced ultrasonography can evaluate the level of renal ischemia-reperfusion injury. • Peak enhancement and wash-in perfusion index are correlated with the renal tubular necrosis rate. • CEUS can detect changes in unilateral renal function without radiation.

p55γ degrades RIP3 via MG53 to suppress ischaemia-induced myocardial necroptosis and mediates cardioprotection of preconditioning

AIMS

Regulated necrosis (necroptosis) and apoptosis are important biological features of myocardial infarction, ischaemia-reperfusion (I/R) injury, and heart failure. However, the molecular mechanisms underlying myocardial necroptosis remain elusive. Ischaemic preconditioning (IPC) is the most powerful intrinsic cardioprotection against myocardial I/R injury. In this study, we aimed to determine whether IPC suppresses I/R-induced necroptosis and the underlying molecular mechanisms.

METHODS AND RESULTS

We generated p55γ transgenic and knockout mice and used ligation of left anterior descending coronary artery to produce an in vivo I/R model. The effects of p55γ and its downstream molecules were subsequently identified using mass spectroscopy and co-immunoprecipitation and pulldown assays. We found that p55γ expression was down-regulated in failing human myocardium caused by coronary heart disease as well as in I/R mouse hearts. Cardiac-specific p55γ overexpression ameliorated the I/R-induced necroptosis. In striking contrast, p55γ deficiency (p55γ-/-) and cardiac-specific deletion of p55γ (p55γc-KO) worsened I/R-induced injury. IPC up-regulated p55γ expression in vitro and in vivo. Using reporter and chromatin immunoprecipitation assays, we found that Hif1α transcriptionally regulated p55γ expression and mediated the cardioprotection of IPC. IPC-mediated suppression of necroptosis was attenuated in p55γ-/- and p55γc-KO hearts. Mechanistically, p55γ overexpression decreased the protein levels of RIP3 rather than the mRNA levels, while p55γ deficiency increased the protein abundance of RIP3. IPC attenuated the I/R-induced up-regulation of RIP3, which was abolished in p55γ-deficient mice. Up-regulation of RIP3 attenuated the p55γ- or IPC-induced inhibition of necroptosis in vivo. Importantly, p55γ directly bound and degraded RIP3 in a ubiquitin-dependent manner. We identified MG53 as the E3 ligase that mediated the p55γ-induced degradation of RIP3. In addition, we also found that p55γ activated the RISK pathway during IPC.

CONCLUSIONS

Our findings reveal that activation of the MG53-RIP3 signal pathway by p55γ protects the heart against I/R-induced necroptosis and underlies IPC-induced cardioprotection.

Pharmacological inhibition of the cysteine protease cathepsin C improves graft function after heart transplantation in rats

BACKGROUND

Heart transplantation (HTX) is the standard treatment for end-stage heart failure. However, reperfusion following an ischemic period can contribute to myocardial injury. Neutrophil infiltration, along with the subsequent release of tissue-degrading neutrophil elastase (NE)-related serine proteases and oxygen-derived radicals, is associated with adverse graft outcomes. The inhibition of cathepsin C (CatC) has been shown to block NE-related protease activation. We hypothesized that the CatC inhibitor BI-9740 improves graft function after HTX.

METHODS

In a rat model of HTX, the recipient Lewis rats were orally administered with either a placebo (n = 12) or BI-9740 (n = 11, 20 mg/kg) once daily for 12 days. Donor hearts from untreated Lewis rats were explanted, preserved in a cardioplegic solution, and subsequently heterotopically implanted. In vivo left-ventricular (LV) graft function was assessed after 1 h of reperfusion. The proteolytic activity of neutrophil serine proteases was determined in bone marrow lysates from BI-9740-treated and control rats. Additionally, myocardial morphological changes were examined, and heart samples underwent immunohistochemistry and western blot analysis.

RESULTS

The NE-related proteolytic activity in bone marrow cell lysates was markedly decreased in the BI-9740-treated rats compared to those of the placebo group. Histopathological lesions, elevated CatC and myeloperoxidase-positive cell infiltration, and nitrotyrosine immunoreactivity with an increased number of poly(ADP-ribose) polymerase (PARP)-1-positive cells were lowered in the hearts of animals treated with BI-9740 compared to placebo groups. Regarding the functional parameters of the implanted graft, improvements were observed in both systolic function (LV systolic pressure 110 ± 6 vs 74 ± 6 mmHg; dP/dtmax 2782 ± 149 vs 2076 ± 167 mmHg/s, LV developed pressure, at an intraventricular volume of 200 µl, p < 0.05) and diastolic function in the hearts of BI-9740 treated animals compared with those receiving the only placebo. Furthermore, the administration of BI-9740 resulted in a shorter graft re-beating time compared to the placebo group. However, this study did not provide evidence of DNA fragmentation, the generation of both superoxide anions and hydrogen peroxide, correlating with the absence of protein alterations related to apoptosis, as evidenced by western blot in grafts after HTX.

CONCLUSIONS

We provided experimental evidence that pharmacological inhibition of CatC improves graft function following HTX in rats.

The role of ferroptosis in cell-to-cell propagation of cell death initiated from focal injury in cardiomyocytes

AIMS

Ferroptosis has grown in importance as a key factor in ischemia-reperfusion (I/R) injury. This study explores the mechanism underlying fibrotic scarring extending along myofibers in cardiac ischemic injury and demonstrates the integral role of ferroptosis in causing a unique cell death pattern linked to I/R injury.

MAIN METHODS

Cadaveric hearts from individuals who had ischemic injury were examined by histological assays. We created a novel model of inducing cell death in H9c2 cells, and used it to demonstrate ferroptotic cell death extending in a cell-to-cell manner. Ex vivo Langendorff-perfused hearts were used alongside the model to replicate cell death extension along myofibers while also demonstrating protective effects of a ferroptosis inhibitor, ferrostatin-1 (Fer-1).

KEY FINDINGS

Human hearts from individuals who had I/R injury demonstrated scarring along myofibers that was consistent with mouse models, suggesting that cell death extended from cell-to-cell. Treatment with Ras-selective lethal 3 (RSL3), a ferroptosis inducer, and exposure to excess iron exacerbated cell death propagation in in vitro models, and inhibition of ferroptosis by Fer-1 blunted this effect in both settings. In ex vivo models, Fer-1 was sufficient to reduce cell death along the myofibers caused by external injury.

SIGNIFICANCE

The unique I/R injury-induced pattern of cell death along myofibers requires novel injury models that mimic this phenomenon, thus we established new methods to replicate it. Ferroptosis is important in propagating injury between cells and better understanding this mechanism may lead to therapeutic responses that limit I/R injury.

Mild hypothermia attenuates ischaemia/reperfusion injury: insights from serial non-invasive pressure-volume loops

AIMS

Mild hypothermia, 32-35°C, reduces infarct size in experimental studies, potentially mediating reperfusion injuries, but human trials have been ambiguous. To elucidate the cardioprotective mechanisms of mild hypothermia, we analysed cardiac performance in a porcine model of ischaemia/reperfusion, with serial cardiovascular magnetic resonance (CMR) imaging throughout 1 week using non-invasive pressure-volume (PV) loops.

METHODS AND RESULTS

Normothermia and Hypothermia group sessions (n = 7 + 7 pigs, non-random allocation) were imaged with Cardiovascular magnetic resonance (CMR) at baseline and subjected to 40 min of normothermic ischaemia by catheter intervention. Thereafter, the Hypothermia group was rapidly cooled (mean 34.5°C) for 5 min before reperfusion. Additional CMR sessions at 2 h, 24 h, and 7 days acquired ventricular volumes and ischaemic injuries (unblinded analysis). Stroke volume (SV: -24%; P = 0.029; Friedmans test) and ejection fraction (EF: -20%; P = 0.068) were notably reduced at 24 h in the Normothermia group compared with baseline. In contrast, the decreases were ameliorated in the Hypothermia group (SV: -6%; P = 0.77; EF: -6%; P = 0.13). Mean arterial pressure remained stable in Normothermic animals (-3%, P = 0.77) but dropped 2 h post-reperfusion in hypothermic animals (-18%, P = 0.007). Both groups experienced a decrease and partial recovery pattern for PV loop-derived variables over 1 week, but the adverse effects tended to attenuate in the Hypothermia group. Infarct sizes were 10 ± 8% in Hypothermic and 15 ± 8% in Normothermic animals (P = 0.32). Analysis of covariance at 24 h indicated that hypothermia has cardioprotective properties incremental to reducing infarct size, such as higher external power (P = 0.061) and lower arterial elastance (P = 0.015).

CONCLUSION

Using non-invasive PV loops by CMR, we observed that mild hypothermia at reperfusion alleviates the heart's work after ischaemia/reperfusion injuries during the first week and preserves short-term cardiac performance. This hypothesis-generating study suggests hypothermia to have cardioprotective properties, incremental to reducing infarct size. The primary cardioprotective mechanism was likely an afterload reduction acutely unloading the left ventricle.

SLC26A11 Inhibition Reduces Oncotic Neuronal Death and Attenuates Stroke Reperfusion Injury

Neuronal swelling is a pathological feature of stroke which contributes to the formation of cytotoxic edema. Under hypoxic condition, aberrant accumulation of sodium and chloride ions inside neurons increases osmotic pressure, leading to cell volume increase. Sodium entry pathway in neurons has been studied extensively. Here, we determine whether SLC26A11 is the major chloride entry pathway under hypoxia and could be the target for protection against ischemic stroke. In this study, electrophysiological properties of chloride current in primary cultured neurons were characterized using low chloride solution, 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid, and SLC26A11-specific siRNA under physiological conditions or ATP-depleted conditions. In vivo effect of SLC26A11 was evaluated on a rat stroke reperfusion model. We found that SLC26A11 mRNA in primary cultured neurons was upregulated as early as 6 h after oxygen glucose deprivation, and later, the protein level was elevated accordingly. Blockade of SLC26A11 activity could reduce chloride entry and attenuate hypoxia-induced neuronal swelling. In the animal stroke model, SLC26A11 upregulation was mainly located in surviving neurons close to the infarct core. SLC26A11 inhibition ameliorates infarct formation and improves functional recovery. These findings demonstrate that SLC26A11 is a major pathway for chloride entry in stroke, contributing to neuronal swelling. Inhibition of SLC26A11 could be a novel therapeutic strategy for stroke.

Risk factors for myocardial injury during living donor liver transplantation in pediatric patients with biliary atresia

BACKGROUND

Cold ischemia-reperfusion of the liver is an inevitable occurrence in liver transplantation that may also cause damage to the heart. Perioperative myocardial injury during liver transplantation can increase the incidence of postoperative mortality, but there is little research on the incidence of myocardial injury in children who undergo living donor liver transplantation (LDLT). Therefore, this study mainly explores the independent risk factors for myocardial injury in children who undergo LDLT.

AIM

To analyze the data of children who underwent LDLT to determine the risk factors for intraoperative myocardial injury.

METHODS

We retrospectively analyzed the inpatient records of pediatric patients who underwent LDLT in Tianjin First Central Hospital from January 1, 2020, to January 31, 2022. Recipient-related data and donor-related data were collected. The patients were divided into a myocardial injury group and a nonmyocardial injury group according to the value of the serum cardiac troponin I at the end of surgery for analysis. Univariate analysis and multivariate logistic regression were used to evaluate the risk factors for myocardial injury during LDLT in pediatric patients.

RESULTS

A total of 302 patients met the inclusion criteria. The myocardial injury group had 142 individuals (47%), and the nonmyocardial injury group included 160 patients (53%). Age, height, and weight were significantly lower in the myocardial injury group (P < 0.001). The pediatric end-stage liver disease (PELD) score, total bilirubin, and international standardized ratio were significantly higher in the myocardial injury group (P < 0.001). The mean arterial pressure, lactate, hemoglobin before reperfusion, duration of the anhepatic phase, cold ischemic time, incidence of postreperfusion syndrome (PRS), and fresh frozen plasma transfusion were significantly different between the two groups (P < 0.05). The postoperative intensive care unit stay and peak total bilirubin values in the first 5 d after LDLT were significantly higher in the myocardial injury group (P < 0.05). The pediatric patients with biliary atresia in the nonmyocardial injury group who underwent LDLT had a considerably higher one-year survival rate than those in the myocardial injury group (P = 0.015). Multivariate logistic regression revealed the following independent risk factors for myocardial injury: a high PELD score [odds ratio (OR) = 1.065, 95% confidence interval (CI): 1.013-1.121; P = 0.014], a long duration of the anhepatic phase (OR = 1.021, 95%CI: 1.003-1.040; P = 0.025), and the occurrence of intraoperative PRS (OR = 1.966, 95%CI: 1.111-3.480; P = 0.020).

CONCLUSION

A high PELD score, a long anhepatic phase duration, and the occurrence of intraoperative PRS were independent risk factors for myocardial injury during LDLT in pediatric patients with biliary atresia.

Interferon-γ priming enhances the therapeutic effects of menstrual blood-derived stromal cells in a mouse liver ischemia-reperfusion model

BACKGROUND

Mesenchymal stem cells (MSCs) have been used in liver transplantation and have certain effects in alleviating liver ischemia-reperfusion injury (IRI) and regulating immune rejection. However, some studies have indicated that the effects of MSCs are not very significant. Therefore, approaches that enable MSCs to exert significant and stable therapeutic effects are worth further study.

AIM

To enhance the therapeutic potential of human menstrual blood-derived stromal cells (MenSCs) in the mouse liver ischemia-reperfusion (I/R) model via interferon-γ (IFN-γ) priming.

METHODS

Apoptosis was analyzed by flow cytometry to evaluate the safety of IFN-γ priming, and indoleamine 2,3-dioxygenase (IDO) levels were measured by quantitative real-time reverse transcription polymerase chain reaction, western blotting, and ELISA to evaluate the efficacy of IFN-γ priming. In vivo, the liver I/R model was established in male C57/BL mice, hematoxylin and eosin and TUNEL staining was performed and serum liver enzyme levels were measured to assess the degree of liver injury, and regulatory T cell (Treg) numbers in spleens were determined by flow cytometry to assess immune tolerance potential. Metabolomics analysis was conducted to elucidate the potential mechanism underlying the regulatory effects of primed MenSCs. In vitro, we established a hypoxia/reoxygenation (H/R) model and analyzed apoptosis by flow cytometry to investigate the mechanism through which primed MenSCs inhibit apoptosis. Transmission electron microscopy, western blotting, and immunofluorescence were used to analyze autophagy levels.

RESULTS

IFN-γ-primed MenSCs secreted higher levels of IDO, attenuated liver injury, and increased Treg numbers in the mouse spleens to greater degrees than untreated MenSCs. Metabolomics and autophagy analyses proved that primed MenSCs more strongly induced autophagy in the mouse livers. In the H/R model, autophagy inhibitors increased the level of H/R-induced apoptosis, indicating that autophagy exerted protective effects. In addition, primed MenSCs decreased the level of H/R-induced apoptosis via IDO and autophagy. Further rescue experiments proved that IDO enhanced the protective autophagy by inhibiting the mammalian target of rapamycin (mTOR) pathway and activating the AMPK pathway.

CONCLUSION

IFN-γ-primed MenSCs exerted better therapeutic effects in the liver I/R model by secreting higher IDO levels. MenSCs and IDO activated the AMPK-mTOR-autophagy axis to reduce IRI, and IDO increased Treg numbers in the spleen and enhanced the MenSC-mediated induction of immune tolerance. Our study suggests that IFN-γ-primed MenSCs may be a novel and superior MSC product for liver transplantation in the future.

The m6A methylation enzyme METTL14 regulates myocardial ischemia/reperfusion injury through the Akt/mTOR signaling pathway

Herein, we investigated the role of the m⁶A methylation enzyme METTL14 in regulating myocardial ischemia/reperfusion injury (IR/I) through the Akt/mTOR signaling pathway and related biological mechanisms. Enzyme-linked immunosorbent assay (ELISA) and fluorescence quantitative polymerase chain reaction (qPCR) were performed to detect the m⁶A mRNA and METTL3, METTL14, WTAP, and KIAA1429 levels in a mouse myocardial IR/I model. An oxygen-glucose deprivation/reperfusion (OGD/R) model was constructed by transfecting neonatal rat cardiomyocytes (NRCM) with METTL14-knockdown lentivirus. METTL14, Bax, and cleaved-caspase3 mRNA expression levels were detected using fluorescence qPCR. Apoptosis was detected using TUNEL staining. After the IR/I surgery following the adeno-associated virus injection, the METTL14 mRNA and apoptosis-related BAX/BCL2 protein expression was detected using fluorescence qPCR and western blotting, respectively. Degree of cell necrosis was detected using an LDH assay. The oxidative stress response of the myocardial tissue was detected, and IL-6 and IL-1β serum levels were detected using ELISAs. The mice injected with METTL14-knockdown AAV9 adeno-associated virus underwent IR/I surgery after the injection of an Akt/mTOR pathway inhibitor (MK2206) into the myocardial layer. Elevated mRNA m⁶A modification and m⁶A methyltransferase METTL14 levels were observed in the IR/I-injured mouse heart tissues. METTL14 knockdown significantly inhibited the OGD/R- and IR/I-induced apoptosis and necrosis in cardiac myocytes, inhibited IR/I-induced oxidative stress and inflammatory factor secretion, and activated the Akt/ mTOR pathway in vitro and in vivo. Akt/mTOR pathway inhibition significantly attenuated the alleviating effect of METTL14 knockdown on myocardial IR/I injury-induced apoptosis. Knocking down m6A methylase METTL14 inhibits IR/I-induced myocardial apoptosis and necrosis, inhibits myocardial oxidative stress and secretion of inflammatory cytokines, and activates the Akt/mTOR signaling pathway. Hence, METTL14 regulated myocardial apoptosis and necrosis in mice with IR/I through the Akt/mTOR signaling pathway.

Melatonin modulates the aggravation of pyroptosis, necroptosis, and neuroinflammation following cerebral ischemia and reperfusion injury in obese rats

Obesity is well-established as a common comorbidity in ischemic stroke. The increasing evidence has revealed that it also associates with the exacerbation of brain pathologies, resulting in increasingly severe neurological outcomes following cerebral ischemia and reperfusion (I/R) damage. Mechanistically, pyroptosis and necroptosis are novel forms of regulated death that relate to the propagation of inflammatory signals in case of cerebral I/R. Previous studies noted that pyroptotic and necroptotic signaling were exacerbated in I/R brain of obese animals and led to the promotion of brain tissue injury. This study aimed to investigate the roles of melatonin on pyroptosis, necroptosis, and pro-inflammatory pathways occurring in the I/R brain of obese rats. Male Wistar rats were given a high-fat diet for 16 weeks to induce the obese condition, and then were divided into 4 groups: Sham-operated, I/R treated with vehicle, I/R treated with melatonin (10 mg/kg), and I/R treated with glycyrrhizic acid (10 mg/kg). All drugs were administered via intraperitoneal injection at the onset of reperfusion. The development of neurological deficits, cerebral infarction, histological changes, neuronal death, and glial cell hyperactivation were investigated. This study revealed that melatonin effectively improved these detrimental parameters. Furthermore, the processes of pyroptosis, necroptosis, and inflammation were all diminished by melatonin treatment. A summary of the findings is that melatonin effectively reduces ischemic brain pathology and thereby improves post-stroke outcomes in obese rats by modulating pyroptosis, necroptosis, and inflammation.

Predictors for clinical and functional outcomes in stroke patients with first-pass complete recanalization after thrombectomy

BACKGROUND

To identify baseline clinical and radiological/procedural predictors and 24-hour radiological predictors for clinical and functional outcomes in stroke patients obtaining complete recanalization in one pass of mechanical thrombectomy (MT) in an optimal baseline and procedural setting.

METHODS

We conducted a retrospective analysis of prospectively collected data from 924 stroke patients with anterior LVO, ASPECTS ≥6, and pre-stroke mRS =0, who started MT ≤6 hours from symptom onset and obtained first-pass complete recanalization. We performed a first logistic regression model to identify baseline clinical predictors and a second model to identify baseline radiological/procedural predictors. We performed a third model including baseline clinical and radiological/procedural predictors, and a fourth model including independent baseline predictors from the third model plus 24-hour radiological variables (hemorrhagic transformation, HT and cerebral edema, CED).

RESULTS

In the fourth model, higher NIHSS score (OR:1.089) and higher ASPECTS (OR:1.292) were predictors of early neurological improvement (ENI, NIHSS score ≤4 points from baseline or NIHSS score of 0 at 24 hours), whereas older age (OR:0.973), longer procedure time (OR:0.990), HT (OR:0.272), and CED (OR:0.569) were inversely associated with ENI. Older age (OR:0.970), diabetes mellitus (OR:0.456), higher NIHSS score (OR:0.886), general anesthesia (OR:0.454), longer onset-to-groin time (OR:0.996), HT (OR:0.340), and CED (OR:0.361) were inversely associated with 3-month excellent functional outcome (mRS score 0-1), whereas higher ASPECTS (OR:1.294) was predictor of excellent outcome.

CONCLUSIONS

Higher NIHSS score was predictor of ENI, but inversely associated with 3-month excellent outcome. Older age, HT, and CED were inversely associated with both good outcomes.

Oxygen resaturation rate is significantly associated with objectively assessed excessive daytime sleepiness in suspected obstructive sleep apnoea patients

INTRODUCTION

Commonly utilised metrics such as the apnoea-hypopnoea index show limited correlation to excessive daytime sleepiness (EDS). Oxygen desaturation parameters show better predictive power, however oxygen resaturation parameters have not yet been investigated. Oxygen resaturation may represent increased cardiovascular fitness and thus we hypothesized that a higher resaturation rate would be protective against EDS.

METHODS

Oxygen saturation parameters were computed via ABOSA software for adult patients referred for polysomnography and multiple sleep latency test in Israel Loewenstein hospital 2001-2011. EDS was defined as a mean sleep latency (MSL) below 8 min.

RESULTS

1629 patients (75% male, 53% obese, median age of 54 years) were included for analysis. The average desaturation event nadir was 90.4% and resaturation rate 0.59%/second. Median MSL was 9.6 min, and 606 patients met criteria for EDS. Patients who were younger, female, and with larger desaturations had significantly higher resaturation rates (p < 0.001). In multivariate models, adjusted for age, sex, body mass index, and average desaturation depth, resaturation rate showed a significant negative correlation with MSL (z-score standardised beta, -1 (95%CI -0.49, -1.52)), and significantly increased odds ratio (OR) of EDS (OR, 1.28 (95%CI 1.07, 1.53)). The beta associated with resaturation rate was larger, though non-significantly, than that of desaturation depth (difference 0.36 (95% CI -1.34, 0.62), p = 0.470).

CONCLUSION

Oxygen resaturation parameters show significant associations with objectively assessed EDS independent of desaturation parameters. Thus, resaturation and desaturation parameters may reflect differing underlying mechanistic pathways and both be considered novel and appropriate markers for assessing sleep-disordered breathing and associated outcomes.

Coronary microcirculation in nonculprit vessel territory in reperfused acute myocardial infarction

BACKGROUND

There is an ongoing debate on the extension of reperfusion-related microvascular damage (MVD) throughout the remote noninfarcted myocardial regions in patients with ST-elevation myocardial infarction (STEMI) that undergo primary percutaneous intervention (pPCI). The aim of this study was to elucidate the impact of reperfusion on remote microcirculatory territory by analyzing hemodynamic alterations in the nonculprit-vessel in relation to reperfusion.

METHODS

A total of 20 patients with STEMI undergoing pPCI were included. Peri-reperfusion temporal changes in hemodynamic parameters were obtained in angiographically normal nonculprit vessels before and 1-h after reopening of the culprit vessel. Intracoronary pressure and flow velocity data were compared using pairwise analyses (before and 1-h after reperfusion).

RESULTS

In the non-culprit vessel, compared to the pre-reperfusion state, mean resting average peak velocity (33.4 ± 9.4 to 25.0 ± 4.9 cm/s, P < 0.001) and mean hyperemic average peak velocity (53.5 ± 14.4 to 42.1 ± 10.66 cm/s, P = 0.001) significantly decreased; whereas baseline (3.2 ± 1.0 to 4.0 ± 1.0 mmHg.cm^-1.s, P < 0.001) and hyperemic microvascular resistance (HMR) (1.9 ± 0.6 to 2.4 ± 0.7 mmHg.cm^-1.s, P < 0.001) and mean zero flow pressure (Pzf) values (32.5 ± 6.9 to 37.6 ± 8.3 mmHg, P = 0.003) significantly increased 1-h after reperfusion. In particular, the magnitude of changes in HMR and Pzf values following reperfusion were more prominent in patients with larger infarct size and with higher extent of MVD in the culprit vessel territory.

CONCLUSION

Reperfusion-related microvascular injury extends to involve remote myocardial territory in relation to the magnitude of the adjacent infarction and infarct-zone MVD. (GUARD Clinical TrialsNCT02732080).

Aspirin Blocks the Infarct-Size Limiting Effect of Ischemic Postconditioning in the Rat

BACKGROUND

Ischemic postconditioning (PostC), repetitive cycles of re-occlusion, and reperfusion of the infarct-related artery immediately after reperfusion have been shown to limit myocardial infarct size in various animal models. Yet, translating the model into the clinical setting was disappointing, several clinical trials showing neutral effect. We hypothesized that aspirin loading could explain the differences between the pre-clinical and clinical studies.

METHODS

Male Sprague Dawley rats were subjected to 30-min coronary artery ligation. At 25 min of ischemia, animals received intravenous aspirin (20 mg/kg) or vehicle. Upon reperfusion half of the rats were randomized to PostC (3 cycles of 10-s re-occlusion/10-s reperfusion. After 4-h reperfusion, rats were euthanized. Area at risk was assessed by blue dye and infarct size by 2,3,5-triphenyl-tetrazolium-chloride (TTC).

RESULTS

Body weight and the size of the ischemic area at risk were comparable among groups. Infarct size expressed as a percentage of the ischemic area at risk was significantly smaller in the PostC group (13.9 ± 0.4%; p < 0.001) compared to the control group (31.0 ± 2.2%). Aspirin alone had no effect on infarct size (29.0 ± 2.6%). Yet, aspirin completely blocked the protective effect of PostC (33.3 ± 1.1%).

CONCLUSIONS

Aspirin, administered before reperfusion, blocks the infarct size limiting effects of PostC in the rat.

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.

Re-Exploring the Inflammation-Related Core Genes and Modules in Cerebral Ischemia

The genetic transcription profile of brain ischemic and reperfusion injury remains elusive. To address this, we used an integrative analysis approach including differentially expressed gene (DEG) analysis, weighted-gene co-expression network analysis (WGCNA), and pathway and biological process analysis to analyze data from the microarray studies of nine mice and five rats after middle cerebral artery occlusion (MCAO) and six primary cell transcriptional datasets in the Gene Expression Omnibus (GEO). (1) We identified 58 upregulated DEGs with more than 2-fold increase, and adj. p < 0.05 in mouse datasets. Among them, Atf3, Timp1, Cd14, Lgals3, Hmox1, Ccl2, Emp1, Ch25h, Hspb1, Adamts1, Cd44, Icam1, Anxa2, Rgs1, and Vim showed significant increases in both mouse and rat datasets. (2) Ischemic treatment and reperfusion time were the main confounding factors in gene profile changes, while sampling site and ischemic time were not. (3) WGCNA identified a reperfusion-time irrelevant and inflammation-related module and a reperfusion-time relevant and thrombo-inflammation related module. Astrocytes and microglia were the main contributors of the gene changes in these two modules. (4) Forty-four module core hub genes were identified. We validated the expression of unreported stroke-associated core hubs or human stroke-associated core hubs. Zfp36 mRNA was upregulated in permanent MCAO; Rhoj, Nfkbiz, Ms4a6d, Serpina3n, Adamts-1, Lgals3, and Spp1 mRNAs were upregulated in both transient MCAO and permanent MCAO; and NFKBIZ, ZFP3636, and MAFF proteins, unreported core hubs implicated in negative regulation of inflammation, were upregulated in permanent MCAO, but not in transient MCAO. Collectively, these results expand our knowledge of the genetic profile involved in brain ischemia and reperfusion, highlighting the crucial role of inflammatory disequilibrium in brain ischemia.

Evaluating the role of intravenous pentoxifylline administration on primary percutaneous coronary intervention success rate in patients with ST-elevation myocardial infarction (PENTOS-PCI)

Ischemia reperfusion injury can lead to further myocardiocyte damage in patients with ST-elevation myocardial infarction (STEMI). Pentoxifylline is a methylxanthine derivative with known anti-inflammatory, antioxidant, vasodilator, and rheological properties which can be a promising agent in preventing reperfusion injury. PENTOS-PCI is a single-center, randomized, double-blind, placebo-controlled trial which evaluated the efficacy and safety of preprocedural administration of intravenous pentoxifylline in patients undergoing primary percutaneous coronary intervention (PCI). Patients with acute STEMI who were eligible for PCI were randomized to receive either 100-mg intravenous infusion of pentoxifylline or placebo, prior to transferring to catheterization laboratory. Overall, 161 patients were included in our study of whom 80 patients were assigned to pentoxifylline and 81 to the control groups. Per-protocol analysis of primary endpoint indexing PCI's success rate as measured by thrombolysis in myocardial infarction (TIMI) flow grade 3 was not significantly different between pentoxifylline and placebo (71.3% and 66.3% respectively, P = 0.40). In addition, pentoxifylline could not improve secondary angiographic endpoints including myocardial blush grade 3 (87.5% and 85.2%, P = 0.79) and corrected TIMI frame count (22.8 [± 9.0] and 24.0 [± 5.1], P = 0.33) in the intervention and placebo groups respectively. The rates of major adverse cardiac and treatment emergent adverse effects were not significantly different between the two groups. Administration of intravenous pentoxifylline before primary PCI did not improve the success rate of the procedure in patients with STEMI. Intravenous administration of pentoxifylline was well tolerated, and there were no significant differences regarding adverse drug reactions in the two groups. Panel A, background: pentoxifylline is a methylxanthine derivative with known anti-inflammatory, antioxidant, vasodilator, and rheological properties which can be a promising agent in preventing reperfusion injury. Panel B: study design and main results of the PENTOS-PCI trial. cTFC corrected TIMI frame count, ED emergency department, IRI ischemia reperfusion injury, MBG myocardial blush grade, PCI percutaneous coronary intervention, PPCI primary PCI, PTX pentoxifylline, ROS reactive oxygen species, SD standard deviation, STEMI ST-elevation myocardial infarction, TIMI thrombolysis in myocardial infarction.

Aortic ischemia-reperfusion injury and potency of fluoxetine

Objectives

Due to cross-clamping of the aorta during aortic aneurysm surgeries, ischemia-reperfusion (IR) develops, and it may cause damage to the aorta itself or even to remote organs by oxidative stress or inflammation. Fluoxetine (FLX) which might be used in the preoperative period for its tranquilizing effect also has antioxidant effects in short-term use. The purpose of our study is to examine whether FLX protects aorta tissue, against the damage caused by IR.

Materials and Methods

Three groups of Wistar rats were formed randomly. 1) Control group (sham-operated), 2) IR group (60 min ischemia+120 min perfusion), and 3) FLX+IR group (FLX dose was 20 mg/kg for 3 days IP before IR). At the end of each procedure, aorta samples were collected, and oxidant-antioxidant, anti-inflammatory, and anti-apoptotic status of the aorta were evaluated. Histological examinations of the samples were provided.

Results

Levels of LOOH, MDA, ROS, TOS, MPO, TNFα, IL-1β, IL-6, NF-kB, MMP-9, caspase-9, 8-OHdG, NO, and HA were found to be significantly increased in the IR group compared with control (P<0.05) and SOD, GSH, TAS, and IL-10 levels were significantly lower (P<0.05). FLX significantly decreased LOOH, MDA, ROS, TOS, MPO, TNFα, IL-1β, IL-6, NF-kB, MMP-9, caspase-9, 8-OHdG, NO, and HA levels in the FLX+IR group compared with IR group (P<0.05) and increased IL-10, SOD, GSH, and TAS (P<0.05). FLX administration prevented the deterioration of aortic tissue damage.

Conclusion

Our study is the first study that demonstrates FLX-mediated suppression of IR injury in the infrarenal abdominal aorta by antioxidant, anti-inflammatory, and anti-apoptotic properties.

Protective effects of gallic acid and SGK1 inhibitor on oxidative stress and cardiac damage in an isolated heart model of ischemia/reperfusion injury in rats

Objectives

Oxidative stress and serum and glucocorticoid-induced Kinase 1 gene (SGK1) perform a central role in the consequences of ischemia in the heart. This research aimed to investigate the effect of coadministration of gallic acid and the GSK650394 (as SGK1 gene inhibitor) on the ischemic complications of a rat model of cardiac ischemia/reperfusion (I/R) injury.

Materials and Methods

Sixty male Wistar rats were divided into 6 groups with or without pretreatment with gallic acid for 10 days. After that, the heart was isolated and perfused with Krebs-Henseleit solution. A 30 min of ischemia was performed followed by a 60 min reperfusion. In 2 groups, GSK650394 was infused 5 min before ischemia induction. Ten minutes after reperfusion commencement, cardiac marker enzyme (CK-MB, LDH, and cTn-I) activities were measured in the cardiac perfusate. At the end of reperfusion, the activity of anti-oxidant enzymes (Catalase, Superoxide dismutase, and Glutathione peroxidase), lipid peroxidation (MDA), total anti-oxidant capacity (TAC), intracellular reactive oxygen species (ROS), infarct size, and SGK1 gene expression were measured in the heart tissue.

Results

The results indicated that dual therapy with both drugs significantly improved endogenous anti-oxidant enzyme activity and TAC more than each drug alone. However, the heart marker enzymes (CK-MB, LDH, and cTn-I), MDA, ROS, infarct size, and SGK1 gene expression were reduced significantly compared with the ischemic group.

Conclusion

The results of this study suggest that concomitant administration of both drugs in the case of cardiac I/R injury may have a more beneficial effect than each one alone.

Reperfusion injury in acute ischemic stroke: Tackling the irony of revascularization

Reperfusion injury is an unfortunate consequence of restoring blood flow to tissue after a period of ischemia. This phenomenon can occur in any organ, although it has been best studied in cardiac cells. Based on cardiovascular studies, neuroprotective strategies have been developed. The molecular biology of reperfusion injury remains to be fully elucidated involving several mechanisms, however these mechanisms all converge on a similar final common pathway: blood brain barrier disruption. This results in an inflammatory cascade that ultimately leads to a loss of cerebral autoregulation and clinical worsening. In this article, the authors present an overview of these mechanisms and the current strategies being employed to minimize injury after restoration of blood flow to compromised cerebral territories.

Celastrol targeting Nedd4 reduces Nrf2-mediated oxidative stress in astrocytes after ischemic stroke

Stroke is the second leading cause of death worldwide, and oxidative stress plays a crucial role. Celastrol exhibits strong antioxidant properties in several diseases; however, whether it can affect oxidation in cerebral ischemic-reperfusion injury (CIRI) remains unclear. This study aimed to determine whether celastrol could reduce oxidative damage during CIRI and to elucidate the underlying mechanisms. Here, we found that celastrol attenuated oxidative injury in CIRI by upregulating nuclear factor E2-related factor 2 (Nrf2). Using alkynyl-tagged celastrol and liquid chromatography-tandem mass spectrometry, we showed that celastrol directly bound to neuronally expressed developmentally downregulated 4 (Nedd4) and then released Nrf2 from Nedd4 in astrocytes. Nedd4 promoted the degradation of Nrf2 through K48-linked ubiquitination and thus contributed to astrocytic reactive oxygen species production in CIRI, which was significantly blocked by celastrol. Furthermore, by inhibiting oxidative stress and astrocyte activation, celastrol effectively rescued neurons from axon damage and apoptosis. Our study uncovered Nedd4 as a direct target of celastrol, and that celastrol exerts an antioxidative effect on astrocytes by inhibiting the interaction between Nedd4 and Nrf2 and reducing Nrf2 degradation in CIRI.

Imatinib attenuates reperfusion injury in a rat model of acute myocardial infarction

Following an acute myocardial infarction, reperfusion of an occluded coronary artery is often accompanied by microvascular injury, leading to worse long-term prognosis. Experimental studies have revealed the potential of tyrosine-kinase inhibitor imatinib to reduce vascular leakage in various organs. Here, we examined the potential of imatinib to attenuate microvascular injury in a rat model of myocardial reperfusion injury. Isolated male Wistar rat hearts (n = 20) in a Langendorff system and male Wistar rats (n = 37) in an in vivo model were randomly assigned to imatinib or placebo and subjected to ischaemia and reperfusion. Evans-blue/Thioflavin-S/TTC staining and Cardiac Magnetic Resonance Imaging were performed to assess the extent of reperfusion injury. Subsequently, in vivo hearts were perfused ex vivo with a vascular leakage tracer and fluorescence and electron microscopy were performed. In isolated rat hearts, imatinib reduced global infarct size, improved end-diastolic pressure, and improved rate pressure product recovery compared to placebo. In vivo, imatinib reduced no-reflow and infarct size with no difference between imatinib and placebo for global cardiac function. In addition, imatinib showed lower vascular resistance, higher coronary flow, and less microvascular leakage in the affected myocardium. At the ultrastructural level, imatinib showed higher preserved microvascular integrity compared to placebo. We provide evidence that low-dose imatinib can reduce microvascular injury and accompanying myocardial infarct size in a rat model of acute myocardial infarction. These data warrant future work to examine the potential of imatinib to reduce reperfusion injury in patients with acute myocardial infarction.

The Rescue on Reperfusion Damage in Cerebral Infarction by Nelonemdaz (RODIN) Trial: Protocol for a Double-Blinded Clinical Trial of Nelonemdaz in Patients with Hyperacute Ischemic Stroke and Endovascular Thrombectomy

BACKGROUND AND PURPOSE

Nelonemdaz (Neu2000) has both selective antagonism against 2B subunit of N-methyl-D-aspartate receptor and antioxidant activity. This drug provides sufficient evidence of neuroprotection in acute cerebral ischemia/reperfusion models. This phase III trial aims to determine this effect in patients.

DESIGN

The Rescue on Reperfusion Damage in Cerebral Infarction by Nelonemdaz is a multicenter, double-blinded clinical trial. A total of 496 patients will be randomly assigned into the nelonemdaz (a total of 5,250 mg divided by 10 times for 5 days) and placebo groups. Patients will be included if they have an acute ischemic stroke (National Institutes of Health Stroke Scale score ≥8) caused by intracranial large vessel occlusion in the anterior circulation (Alberta Stroke Program Early CT Score ≥4), and if they are expected to undergo endovascular thrombectomy within 12 hours after stroke onset.

ENDPOINTS

The primary endpoint is a favorable shift in the modified Rankin Scale (mRS) score at 90 days after the first dose of drug. The data will be analyzed by the Cochran-Mantel-Haenszel shift test. The secondary endpoints include functional independence (mRS 0-2) at 35 and 90 days, the favorable shift of mRS at 35 days, the proportion of mRS 0 at 35 and 90 days, and the occurrence rates of symptomatic intracranial hemorrhage within 7 days.

CONCLUSION

This trial will clarify the efficacy and safety of nelonemdaz in patients with acute ischemic stroke and endovascular thrombectomy. This study has been registered at ClinicalTrials. gov (NCT05041010).

Peroxiredoxin 1 alleviates oxygen-glucose deprivation/ reoxygenation injury in N2a cells via suppressing the JNK/caspase-3 pathway

Objectives

Cerebral ischemia/reperfusion (I/R) injury inevitably aggravates the initial cerebral tissue damage following a stroke. Peroxiredoxin 1 (Prdx1) is a representative protein of the endogenous antioxidant enzyme family that regulates several reactive oxygen species (ROS)-dependent signaling pathways, whereas the JNK/caspase-3 proapoptotic pathway has a prominent role during cerebral I/R injury. This study aimed to examine the potential mechanism of Prdx1 in Neuro 2A (N2a) cells following oxygen-glucose deprivation and reoxygenation (OGD/R) injury.

Materials and Methods

N2a cells were exposed to OGD/R to simulate cerebral I/R injury. Prdx1 siRNA transfection and the JNK inhibitor (SP600125) were used to interfere with their relative expressions. CCK-8 assay, flow cytometry, and lactate dehydrogenase (LDH) assay were employed to determine the viability and apoptosis of N2a cells. The intracellular ROS content was assessed using ROS Assay Kit. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analyses were conducted to detect the expression levels of Prdx1, JNK, phosphorylated JNK (p-JNK), and cleaved caspase-3.

Results

Firstly, Prdx1, p-JNK, and cleaved caspase-3 expression were significantly induced in OGD/R-exposed N2a cells. Secondly, the knockdown of Prdx1 inhibited cell viability and increased apoptosis rate, expression of p-JNK, and cleaved caspase-3 expression. Thirdly, SP600125 inhibited the JNK/caspase-3 signaling pathway and mitigated cell injury following OGD/R. Finally, SP600125 partially reversed Prdx1 down-regulation-mediated cleaved caspase-3 activation and OGD/R damage in N2a cells.

Conclusion

Prdx1 alleviates the injury to N2a cells induced by OGD/R via suppressing JNK/caspase-3 pathway, showing promise as a potential therapeutic for cerebral I/R injury.

Delayed revascularization of extremities following vascular injuries: Challenges and outcome

Purpose

In developing countries delayed presentation following major vascular injury is common due to limited vascular trauma units; delay in diagnosis and time lost in transit which pose a major challenge for limb salvage. Aim of this study was to assess limb survival and complications after delayed revascularization of extremity following major vascular injury.

Method

20 patients, (19 males and 1 female, mean age 31.55 years) with major extremity vascular injury who presented >8 h after vascular trauma were included in this study. All patients had road traffic accidents as the cause of extremity injury. These patients were operated by primary vascular repairs, thrombectomy and/or interposition vein graft along with fixation of concomitant skeletal trauma.

Results

The commonest vessel injured was popliteal artery. The mean time of limb revascularization was 30.8 h. Limb salvage rate was 95% and there was no perioperative mortality. 9 patients developed postoperative complications including sloughing of leg muscles (4), foot drop (3) pseudo aneurysm (1) and reperfusion injury (1). At 6 months follow-up all the patients were able to walk with full weight bearing and there was no chronic ischemia, pain or sinuses.

Conclusion

Limb salvage can be achieved with good results in patients with delayed revascularization in selected cases. However; delayed revascularization leads to long and protracted postoperative course with high chances of vascular and neurological complications.

The effect of Tianjiang Xueshuantong Wan pills on ischemia-reperfusion injury after thrombolysis in acute cerebral infarction

OBJECTIVE

The aim of this study is to investigate the effect of Tianjiang Xueshuantong Wan pills on reperfusion injury after venous thrombolysis in acute cerebral infarction.

METHODS

The strategy used in this study is a randomised controlled clinical trial. In total, 72 cases were included, with 36 in the trial group and 36 in the control group, with a 1:1 ratio. Both groups were given standardised treatment for acute cerebral infarction. Based on the rt-PA intravenous thrombolysis, the test group took Tianjiang Xueshuantong Wan pills orally, whereas the control group solely utilised rt-PA for intravenous thrombolysis and did not take the test medicine orally. The patients' intracranial hemorrhage was clarified by head CT scan, and the occurrence of reperfusion injury was recorded during the entire trial.

RESULTS

There were no significant differences in serum IL-6, MDA, SOD and TNF concentrations and NIHSS scores between the two groups before therapy (P > 0.05). After treatment, the serum concentrations of IL-6, MDA and TNF in the experimental group were significantly decreased compared with the control group, while the serum concentrations of SOD were significantly increased compared with the control group, with statistical significance (P > 0.05). After seven days of treatment, the total effective rate in the experimental group was 88.89%, while the data in the control group was 75%. There was a statistically significant difference between the experimental and control groups.

CONCLUSION

Tianjiang Xueshuantong Wan pills can effectively prevent reperfusion injury following intravenous thrombolysis in individuals with cerebral infarction while improving patients' neurological deficits.

UpStreAm doxycycline in ST-eLeVation myocArdial infarction - targetinG infarct hEaling and ModulatIon (SALVAGE-MI trial)

BACKGROUND AND AIMS

Experimental studies demonstrate protective effects of doxycycline on myocardial ischemia-reperfusion injury. The trial investigated whether doxycycline administered prior to reperfusion in patients presenting with ST-elevation myocardial infarction (STEMI) reduces infarct size (IS) and ameliorates adverse left ventricular (LV) remodeling.

METHODS

In this randomized, double-blind, placebo-controlled trial, patients presenting with STEMI undergoing primary percutaneous coronary intervention (PPCI) were randomized to either intravenous doxycycline or placebo prior to reperfusion followed by 7-days of oral doxycycline or placebo. The primary outcome was final IS adjusted for area-at-risk (fIS/AAR) measured on two cardiac magnetic resonance scans ∼6 months apart.

RESULTS

Of 103 participants, 50 were randomized to doxycycline and 53 to placebo and were matched for age (59 ± 12 vs. 60 ± 10 years), male sex (92% vs. 79%), diabetes mellitus (26% vs. 11%) and left anterior descending artery occlusion (50% vs. 49%), all p > 0.05. Patients treated with doxycycline had a trend for larger fIS/AAR (0.79 [0.5-0.9] vs. 0.61 [0.47-0.76], p = 0.06), larger fIS at 6 months (18.8% [12-26] vs. 13.6% [11-21], p = 0.08), but similar acute IS (21.7% [17-34] vs. 19.4% [14-27], p = 0.19) and AAR (26% [20-36] vs. 24.7% [16-31], p = 0.22) compared to placebo. Doxycycline did not ameliorate adverse LV remodeling (%Δend-diastolic volume index, 1.1% [-3.8-8.4] vs. -1.34% [-6.1-5.8], p = 0.42) and was independently associated with larger fIS (regression coefficient = 0.175, p = 0.03).

CONCLUSION

Doxycycline prior to PPCI neither reduced IS acutely or at 6 months nor attenuated adverse LV remodeling. These data raise safety concerns regarding doxycycline use in STEMI for infarct modulation and healing.

[New aspects of perioperative organ protection]

BACKGROUND

Acutely occurring organ damage significantly contributes to morbidity and mortality in the perioperative context.

OBJECTIVE

This article highlights new clinical perspectives on how perioperative organ damage can be prevented and ameliorated by influencing the high mobility group box 1 protein (HMGB1) signaling.

MATERIAL AND METHODS

A MEDLINE search was performed in the fields of clinical and basic research. The presentation of basic mechanisms of perioperative organ damage and the discussion of the importance of HMGB1 in prevention and treatment by pharmaceutical and nonpharmaceutical interventions are the focus of the review.

RESULTS

The HMGB1 is a central element in the pathogenesis of septic and aseptic inflammation-induced organ damage. Remote ischemic preconditioning (RIPC) and dexmedetomidine are highly effective approaches to mitigate or prevent organ damage.

CONCLUSION

The RIPC and dexmedetomidine offer protective properties in ischemia-reperfusion injury as well as in inflammation-related organ damage, which are mediated by HMGB1, among others. This effectively protects the kidneys, heart, lungs, liver and brain. The application of these concepts should be considered in routine clinical practice.

Beneficial Effects of Insulin on Ischemia Reperfusion Injury in Human Skeletal Muscle

PURPOSE

Exaggerated leucocyte activity is a crucial step in the pathophysiology of skeletal muscle ischemia-reperfusion injury (IRI). We tested the hypothesis that insulin, via its' anti-leukocyte activity, attenuates skeletal muscle IRI in humans.

MATERIALS AND METHODS

This randomized, blinded, placebo-controlled trial was conducted in patients with skeletal muscle ischemia who required revascularization. Treatment protocols were similar among them except for the insulin group, which received an infusion of insulin at 2.5 U/h. The degree of endothelial adhesiveness; leukocyte activity and pro-inflammatory status via P-selectin, tumor necrosis factor (TNF)-alpha, and myeloperoxidase (MPO) levels in the venous effluent; and clinical outcomes were measured.

RESULTS

Twenty-four consenting patients were randomized to the insulin or control group. There were no significant differences between the two groups except for the median serum insulin level, which was higher in the insulin group (P<0.01). No serious intervention-related adverse events were observed. P-selectin (55.04-99.86 pg/mL; P<0.001), MPO (110.8-160.6 pg/mL; P<0.001), and TNF-alpha (12.16-36.01 pg/mL; P<0.001) levels demonstrated a significant increase post-reperfusion in the 'control' group, reaching a peak value at 2 hours post-reperfusion. The increase in all three markers from baseline was significantly diminished in the insulin group at the two-hour (P-selectin, P=0.001; MPO, P=0.001; TNF-alpha, P=0.005) and four-hour (P-selectin, P=0.003; MPO, P=0.002; TNF-alpha, P=0.01) intervals. The differences in clinical outcomes between the insulin and control groups were not statistically significant.

CONCLUSION

In clinical practice, insulin has the potential to attenuate the severity of skeletal muscle IRI inhibiting P-selectin, MPO, and TNF-alpha levels.

Effect of cardiac output - guided hemodynamic management on acute lung injury in pediatric living donor liver transplantation

BACKGROUND

Acute lung injury (ALI) after liver transplantation (LT) may lead to acute respiratory distress syndrome, which is associated with adverse postoperative outcomes, such as prolonged hospital stay, high morbidity, and mortality. Therefore, it is vital to maintain hemodynamic stability and optimize fluid management. However, few studies have reported cardiac output-guided (CO-G) management in pediatric LT.

AIM

To investigate the effect of CO-G hemodynamic management on early postoperative ALI and hemodynamic stability during pediatric living donor LT.

METHODS

A total of 130 pediatric patients scheduled for elective living donor LT were enrolled as study participants and were assigned to the control group (65 cases) and CO-G group (65 cases). In the CO-G group, CO was considered the target for hemodynamic management. In the control group, hemodynamic management was based on usual perioperative care guided by central venous pressure, continuous invasive arterial pressure, urinary volume, etc. The primary outcome was early postoperative ALI. Secondary outcomes included other early postoperative pulmonary complications, readmission to the intense care unit (ICU) for pulmonary complications, ICU stay, hospital stay, and in-hospital mortality.

RESULTS

The incidence of early postoperative ALI was 27.7% in the CO-G group, which was significantly lower than that in the control group (44.6%) (P < 0.05). During the surgery, the incidence of postreperfusion syndrome was lower in the CO-G group (P < 0.05). The level of intraoperative positive fluid transfusions was lower and the rate of dobutamine use before portal vein opening was higher, while the usage and dosage of epinephrine during portal vein opening and vasoactive inotropic score after portal vein opening were lower in the CO-G group (P < 0.05). Compared to the control group, serum inflammatory factors (interleukin-6 and tumor necrosis factor-α), cardiac troponin I, and N-terminal pro-brain natriuretic peptide were lower in the CO-G group after the operation (P < 0.05).

CONCLUSION

CO-G hemodynamic management in pediatric living-donor LT decreases the incidence of early postoperative ALI due to hemodynamic stability through optimized fluid management and appropriate administration of vasopressors and inotropes.

Reassessment of a Decade of Experience on Testicular Torsion: Are We Making a Mistake?

INTRODUCTION

Testicular torsion is a serious surgical emergency of children. Prompt recognition and exclusion of other acute scrotal causes are essential for avoiding testicular loss. The aim of this study was to evaluate 10 years of experience with testicular torsion, point out our pitfalls in diagnosis and management, determine our likelihood of performing orchiectomy for potentially reversible injury.

MATERIAL AND METHOD

Records of patients operated for testicular torsion in the last decade were reviewed retrospectively. Clinical findings, symptoms, type of surgery, accuracy of radiological evaluation, and the outcome were analyzed. Orchiectomy specimens were reevaluated and histologically graded to determine the existence of previously undetermined low-grade injury.

RESULTS

In total, 107 children were operated for testicular torsion. Presentation included pain 96 (89.7%), scrotal swelling 48 (44.8%). Doppler ultrasonography was performed in 96 patients with false-negative results in 26 (27%). Testicular salvage occurred in 65 (60.7%) patients of which 6 (9.2%) developed subsequent testicular atrophy. Forty-two (33.9%) patients were treated with orchiectomy and histologic reevaluation, and grading of the specimens revealed 4 (9.7%) low-grade injury which indicates a potential of reversible injury. Seventeen (13.7%) patients had normal testicular anatomy in surgery.

CONCLUSION

Surgical exploration is mandated in case of clinical suspicion for testicular torsion even with a normal flow Doppler ultrasound. Macroscopic evaluation does not always correlate with microscopic findings, and a decision according to it may result in excision of potentially viable testis. Further studies are required to determine the actual risk of contralateral autoimmune damage and increase the rate testicular salvageability after testicular torsion.

Mild Hypothermia Alleviates Complement C5a-Induced Neuronal Autophagy During Brain Ischemia-Reperfusion Injury After Cardiac Arrest

After restoration of spontaneous circulation (ROSC) following cardiac arrest, complements can be activated and excessive autophagy can contribute to the brain ischemia-reperfusion (I/R) injury. Mild hypothermia (HT) protects against brain I/R injury after ROSC, but the mechanisms have not been fully elucidated. Here, we found that HT significantly inhibited the increases in serum NSE, S100β, and C5a, as well as neurologic deficit scores, TUNEL-positive cells, and autophagic vacuoles in the pig brain cortex after ROSC. The C5a receptor 1 (C5aR1) mRNA and the C5a, C5aR1, Beclin 1, LC3-II, and cleaved caspase-3 proteins were significantly increased, but the P62 protein and the PI3K/Akt/mTOR pathway-related proteins were significantly reduced in pigs after ROSC or neuronal oxygen-glucose deprivation/reoxygenation. HT could significantly attenuate the above changes in NT-treated neurons. Furthermore, C5a treatment induced autophagy and apoptosis and reduced the PI3K/Akt/mTOR pathway-related proteins in cultured neurons, which could be reversed by C5aR1 antagonist PMX205. Our findings demonstrated that C5a could bind to C5aR1 to induce neuronal autophagy during the brain I/R injury, which was associated with the inhibited PI3K/Akt/mTOR pathway. HT could inhibit C5a-induced neuronal autophagy by regulating the C5a-C5aR1 interaction and the PI3K/Akt/mTOR pathway, which might be one of the neuroprotective mechanisms underlying I/R injury. The C5a receptor 1 (C5aR1) mRNA and the C5a, C5aR1, Beclin 1, LC3-II, and cleaved caspase-3 proteins were significantly increased, but the P62 protein and the PI3K/Akt/mTOR pathway-related proteins were significantly reduced in pigs after ROSC or neuronal oxygen-glucose deprivation/reoxygenation. Mild hypothermia (HT) could significantly attenuate the above changes in NT-treated neurons. Furthermore, C5a treatment induced autophagy and apoptosis and reduced the PI3K/Akt/mTOR pathway-related proteins in cultured neurons, which could be reversed by C5aR1 antagonist PMX205. Proposed mechanism by which HT protects against brain I/R injury by repressing C5a-C5aR1-induced excessive autophagy. Complement activation in response to brain I/R injury generates C5a that can interact with C5aR1 to inactivate mTOR, probably through the PI3K-AKT pathway, which can finally lead to autophagy activation. The excessively activated autophagy ultimately contributes to cell apoptosis and brain injury. HT may alleviate complement activation and then reduce C5a-induced autophagy to protect against brain I/R injury. HT, mild hypothermia; I/R, ischemia reperfusion.

Cervical cord reperfusion injury: a rare complication of spine surgery

BACKGROUND

Anterior cervical discectomy and fusion procedure has been considered the surgical procedure of choice for the management of degenerative cervical myelopathy. Postoperative paresis is one of the most serious and concerning complications. The occurrence of such complications without any clear anatomic explanation (e.g., epidural hematoma) is unusual.

CASE PRESENTATION

A 62-year-old man underwent cervical spine decompression via the anterior approach for marked central canal stenosis and spinal cord compression due to degenerative changes. The operation was performed under neuromonitoring, and a complete discectomy for the levels C3/C4, C5/C6, and C6/C7 was performed. Fluoroscopy confirmed the correct placement of the inserted plates and screws. No motor or sensory deficits were evident after postoperative recovery. However, 1 day later, the patient experienced progressive weakness in his both upper and lower extremities. A whole spine MRI study was performed to exclude epidural hematoma as the possible etiology. Although no localized fluid collection or hematoma was observed, the study demonstrated abnormal signal intensity in the spinal cord on T2-weighted images at the levels C5 to C7. Such findings were consistent with changes in cord reperfusion syndrome. The patient was administered intravenous methylprednisolone therapy. Gradual improvement in the muscle power in his both extremities was noted, and the patient was discharged with a satisfactory outcome. One month later, the MRI study was repeated and showed regression of the previously seen high T2 signal intensity in the cervical spine.

CONCLUSION

Cervical cord reperfusion injury is an extremely rare etiology of neurological deterioration following spinal cord decompressive surgeries. Clinicians need to maintain a high index of suspicion for this complication and should be familiar with its imaging appearance.

Vagus nerve stimulation promotes the M1-to-M2 transition via inhibition of TLR4/NF-κB in microglial to rescue the reperfusion injury

OBJECTIVE

To specify the effect of vagus nerve stimulation (VNS) on microglial polarization following ischemic-reperfusion and further investigate its underlying mechanism.

MATERIALS AND METHODS

Sprague-Dawley rats were randomly divided into the sham, ischemic reperfusion group (IR), IR+VNS groups. VNS intervention lasting for 1 hour was administered after 30 minutes of occlusion. We analyzed the expression of Arginase 1 (Arg1), the number of M2 microglial in the peri-infarction cortex and assessed the neurological scores at the 1, 3, 7 days after reperfusion to determine the research time point. Then, we assessed polarization status of microglial, the infarct volume, neurological scores, the cellular distribution of Toll-like Receptor 4 (TLR4), the TLR4-associated pathway protein and the p-NF-κB in microglial at 3 days after reperfusion.

RESULTS

We found that VNS could increase the specific marker of M2 Arg1 and upregulate the M2 microglial after reperfusion, and the increase of Arg1, M2 microglial and the neurological scores was largest at the 3 days after reperfusion. VNS treatment significantly reduced the number and percent of M1, improved the number and percent of M2 and upregulated the M2 to M1 ratio without changing the number of total microglial at the 3 days after reperfusion. Moreover, VNS reduced the infarct volume and neurological deficits. In addition, VNS significantly reduced the microglial-specific TLR4, inhibited the activated TLR4/MyD88/NF-κB pathway following ischemic-reperfusion, and ultimately suppressed the p-NF-κB in microglial.

CONCLUSION

Our study revealed that VNS can promote the M1-to-M2 phenotype conversion to alleviate inflammatory response and brain injury through inhibition of TLR4/MyD88/NF-κB pathway in microglia following ischemic-reperfusion.

RIP1 Regulates Mitochondrial Fission during Skeletal Muscle Ischemia Reperfusion Injury

BACKGROUND

Dynamin related protein-1 (Drp1)-mediated mitochondrial fission relates to ischemia reperfusion (IR) injury, and its association with necroptosis is implied. We hypothesized that receptor-interacting protein 1 (RIP1), a key kinase in necroptosis, acted as an upstream of Drp1-mediated mitochondrial fission during skeletal muscle IR.

METHODS

Thirty rats were randomized into the SM, IR, NI, MI, and DI group (n = 6). The rats in the SM group were shamly operated, and those in the IR group were subjected to 4-hour ischemia of the right hindlimb that was followed by 4-hour reperfusion. Intraperitoneal administration of Nec-1 1 mg/kg, Mdivi-1 1.2 mg/kg and same volume of DMSO were given before ischemia in the NI, MI and DI groups, respectively. Upon reperfusion, the soleus muscles were harvested to determine morphological changes and the expression of RIP1, total Drp1 and p-Drp1 (Ser616). Moreover, the muscular oxidative stress indicators and plasma muscle damage biomarkers were detected.

RESULTS

IR led to impaired histopathological structures and mitochondrial fragmentation in the soleus muscle tissue, accompanied with increased muscular oxidative stress and muscle injury biomarkers, which could be similarly alleviated by Mdivi-1 and Nec-1 (p < 0.05). RIP1 and p-Drp1 (Ser616) protein levels were significantly upregulated in the soleus muscle subjected to IR injury, this upregulation was attenuated in the NI group, and Mdivi-1 downregulated the protein expression of p-Drp1 (Ser616) but not of RIP1 (p < 0.05).

CONCLUSION

RIP1 functions as an upstream of Drp1-mediated mitochondrial fission in the execution of necroptosis during skeletal muscle IR.

Inhibition of myocardial cathepsin-L release during reperfusion following myocardial infarction improves cardiac function and reduces infarct size

AIMS

Identifying novel mediators of lethal myocardial reperfusion injury that can be targeted during primary percutaneous coronary intervention (PPCI) is key to limiting the progression of patients with ST-elevation myocardial infarction (STEMI) to heart failure. Here, we show through parallel clinical and integrative preclinical studies the significance of the protease cathepsin-L on cardiac function during reperfusion injury.

METHODS AND RESULTS

We found that direct cardiac release of cathepsin-L in STEMI patients (n = 76) immediately post-PPCI leads to elevated serum cathepsin-L levels and that serum levels of cathepsin-L in the first 24 h post-reperfusion are associated with reduced cardiac contractile function and increased infarct size. Preclinical studies demonstrate that inhibition of cathepsin-L release following reperfusion injury with CAA0225 reduces infarct size and improves cardiac contractile function by limiting abnormal cardiomyocyte calcium handling and apoptosis.

CONCLUSION

Our findings suggest that cathepsin-L is a novel therapeutic target that could be exploited clinically to counteract the deleterious effects of acute reperfusion injury after an acute STEMI.