Oxidative damage in clinical ischemia/reperfusion injury: a reappraisal

Biochanin A restored the blood-brain barrier in cerebral ischemia-reperfusion in rats

OBJECTIVE

Blood-brain barrier is a protective layer that regulates the influx and efflux of biological materials for cerebral tissue. The aim of this study was to investigate the effects of Biochanin A on cerebral histopathology and blood-brain barrier immunohistochemically.

METHODS

A total of 24 rats were assigned to three groups: sham, ischemia-reperfusion, and ischemia-reperfusion+Biochanin A. Ischemia-reperfusion was performed by occluding the left carotid artery for 2/24 h. Notably, 20 mg/kg Biochanin A was administered to rats for 7 days after ischemia-reperfusion. Blood was collected for malondialdehyde and total oxidant/antioxidant status analysis. Cerebral tissues were processed for histopathology and further for immunohistochemical analysis.

RESULTS

Malondialdehyde content with total oxidant status value was significantly increased and total antioxidant status values were significantly decreased in the ischemia-reperfusion group compared with the sham group. Biochanin A treatment significantly improved scores in the ischemia-reperfusion+Biochanin A group. The normal histological appearance was recorded in the cerebral sections of the sham group. Degenerated neurons and vascular structures with disrupted integrity of the cerebral cortex were observed after ischemia-reperfusion. Biochanin A alleviated the histopathology in the cerebrum in the ischemia-reperfusion+Biochanin A group. Ischemia-reperfusion injury decreased the expression of blood-brain barrier in the ischemia-reperfusion group compared to the sham group. Administration of Biochanin A upregulated the blood-brain barrier immunoreactivity in the cerebrum by restoring blood-brain barrier.

CONCLUSION

Cerebral ischemia-reperfusion caused an increase in oxidative stress and pathological lesions in the cerebrum. Biochanin A treatment restored the adverse effects of ischemia-reperfusion injury by restoring blood-brain barrier.

Red blood cells as oxygen carrier during normothermic machine perfusion of kidney grafts: Friend or foe?

Renal ex vivo normothermic machine perfusion (NMP) is under development as an assessment tool for high-risk kidney grafts and as a means of achieving more physiologically accurate organ preservation. On-going hemolysis has been reported during NMP, as this technique relies on red blood cells for oxygen delivery. In this study, we confirm the occurrence of progressive hemolysis during 6-hour kidney NMP. NMP-associated erythrostasis in the glomeruli and in peri-glomerular vascular networks points to an interaction between the red blood cells and the graft. Continuous hemolysis resulted in prooxidative changes in the perfusate, which could be quenched by addition of fresh frozen plasma. In a cell-based system, this hemolysis induced redox stress and exhibited toxic effects at high concentrations. These findings highlight the need for a more refined oxygen carrier in the context of renal NMP.

The Multifaceted Nature of Macrophages in Cardiovascular Disease

As the leading cause of mortality worldwide, cardiovascular disease (CVD) represents a variety of heart diseases and vascular disorders, including atherosclerosis, aneurysm, ischemic injury in the heart and brain, arrythmias, and heart failure. Macrophages, a diverse population of immune cells that can promote or suppress inflammation, have been increasingly recognized as a key regulator in various processes in both healthy and disease states. In healthy conditions, these cells promote the proper clearance of cellular debris, dead and dying cells, and provide a strong innate immune barrier to foreign pathogens. However, macrophages can play a detrimental role in the progression of disease as well, particularly those inflammatory in nature. This review will focus on the current knowledge regarding the role of macrophages in cardiovascular diseases.

HH-A, a modified honokiol, protects against cerebral ischemia/reperfusion induced brain injury in rodent via Nrf2/HO-1 signaling pathways

Honokiol, a bioactive component found in Magnolia officinalis, has shown in protecting against ischemic stroke in animal models. However, its poor water solubility has limited its clinical applications. In this study, we introduced a hydrophilic building block on the aromatic ring of honokiol, resulting in the synthesis of four new compounds (HH-A, -B, -C and -D) with significantly improved water solubility. We then investigated the neuroprotective effects of these compounds in mouse and rat models of transient middle cerebral artery occlusion/reperfusion (tMCAO/R) brain injury. Among the compounds tested, HH-A, also known as (S)-6-((3',5-diallyl-2,4'-dihydroxy-[1,1'-biphenyl]-3-yl)amino)-6-oxohexane-1,5-diaminium chloride, showed the most promising results. HH-A was found to significantly reduced the infarct volume and brain edema in mice. It also outperformed the other three compounds and honokiol, even surpassing the effects of edaravone dexborneol. Additionally, HH-A demonstrated dose-dependent improvements in body weight, neurological deficits, and infarct volume. Further analysis in tMCAO/R rat model revealed that HH-A treatment led to significant upregulations of Nrf2 and HO-1 in the brain. HH-A also significantly reduced the expression of HNE, and exhibited anti-apoptotic effects by decreasing the expression of Bax and increasing the expression of Bcl-2. This was further supported by a decrease in the number of TUNEL positive cells. Taken together, the neuroprotective effects of HH-A may be attributed to its ability to target the Nrf2/HO-1 signaling pathway, leading to reduced oxidative stress and apoptosis in the brain. These findings suggest that HH-A has potential as a therapeutic agent for the treatment of ischemic stroke.

GC-MS and GC-MS/MS measurement of malondialdehyde (MDA) in clinical studies: Pre-analytical and clinical considerations

Malondialdehyde (MDA; 1,3-propanedial, OHC-CH2-CHO) is one of the most frequently measured biomarkers of oxidative stress in plasma and serum. L-Arginine (Arg) is the substrate of nitric oxide synthases (NOS), which convert L-arginine to nitric oxide (NO) and L-citrulline. The Arg/NO pathway comprises several members, including the endogenous NOS-activity inhibitor asymmetric dimethylarginine (ADMA) and its major metabolite dimethyl amine (DMA), and nitrite and nitrate, the major NO metabolites. Reliable measurement of MDA and members of the Arg/NO pathway in plasma, serum, urine and in other biological samples, such as saliva and cerebrospinal fluid, is highly challenging both for analytical and pre-analytical reasons. In our group, we use validated gas chromatography-mass spectrometry (GC-MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) methods for the quantitative determination in clinical studies of MDA as a biomarker of oxidative stress, and various Arg/NO metabolites that describe the status of this pathway. Here, the importance of pre-analytical issues, which has emerged from the use of GC-MS and GC-MS/MS in clinico-pharmacological studies, is discussed. Paradigmatically, two studies on the long-term oral administration of L-arginine dihydrochloride to patients suffering from peripheral arterial occlusive disease (PAOD) or coronary artery disease (CAD) were considered. Pre-analytical issues that were addressed include blood sampling, plasma or serum storage, study design (notably in long-term studies), and the alternative of measuring MDA in human urine.

The Oxidative Stress and Nervous Distress Connection in Gastrointestinal Disorders

Oxidative stress is increasingly recognized as a central player in a range of gastrointestinal (GI) disorders, as well as complications stemming from therapeutic interventions. This article presents an overview of the mechanisms of oxidative stress in GI conditions and highlights a link between oxidative insult and disruption to the enteric nervous system (ENS), which controls GI functions. The dysfunction of the ENS is characteristic of a spectrum of disorders, including neurointestinal diseases and conditions such as inflammatory bowel disease (IBD), diabetic gastroparesis, and chemotherapy-induced GI side effects. Neurons in the ENS, while essential for normal gut function, appear particularly vulnerable to oxidative damage. Mechanistically, oxidative stress in enteric neurons can result from intrinsic nitrosative injury, mitochondrial dysfunction, or inflammation-related pathways. Although antioxidant-based therapies have shown limited efficacy, recognizing the multifaceted role of oxidative stress in GI diseases offers a promising avenue for future interventions. This comprehensive review summarizes the literature to date implicating oxidative stress as a critical player in the pathophysiology of GI disorders, with a focus on its role in ENS injury and dysfunction, and highlights opportunities for the development of targeted therapeutics for these diseases.

Stachydrine ameliorates hypoxia reoxygenation injury of cardiomyocyte via enhancing SIRT1-Nrf2 pathway

BACKGROUND

Hypoxia/reoxygenation (H/R)-induced cardiomyocyte cell apoptosis is critical in developing myocardial infarction. Stachydrine (STA), an active constituent of Leonurus heterophyllus sweet, could have a protective effect on myocardial H/R injury, which remains unexplored. Therefore, the study aimed to investigate the protective effects and mechanisms of STA on H/R injury of cardiomyocytes.

METHODS

Rat cardiomyocyte H9c2 cells underwent H/R (hypoxia for 4 h and reoxygenation for 12 h). Cells were pretreated with STA (50 µM) 2 h before H/R. Cardiomyocyte injury was evaluated by CCK-8 assay and lactate dehydrogenase (LDH) release. Apoptosis was assessed by TUNEL staining and caspase-3 activity. Oxidative stress was assessed by lipid oxidation product MDA and a ROS-scavenging enzyme SOD in culture media. Western blot was performed to measure the protein expressions of SIRT1, Nrf2, and heme oxygenase-1 (HO-1).

RESULTS

STA reversed the decrease in cell viability and increased LDH release in H9c2 cells with the H/R insult. STA significantly suppressed oxidative stress, reduced MDA content, and increased SOD activity in H9c2 cells exposed to H/R. STA reduced apoptosis in H9c2 cells exposed to H/R, as evidenced by the reduced TUNEL positive cells and caspase-3 activity. In addition, STA enhanced SIRT1, Nrf2, and HO-1 protein expression in H/R-stimulated H9c2 cells. SIRT1 and Nrf2 involved the protective effect of STA in H/R-exposed H9c2 cells, as the changes in cell viability and caspase-3 activity by STA can be reversed by SIRT1 inhibitor EX-527 or Nrf2 siRNA.

CONCLUSIONS

Our data speculated that STA protects H/R injury and inhibits oxidative stress and apoptosis in cardiomyocytes by activation of the SIRT1-Nrf2 pathway.

Intermittent hypoxia differentially affects metabolic and oxidative stress responses in two species of cyprinid fish

Oxygen fluctuations are common in freshwater habitats and aquaculture and can impact ecologically and economically important species of fish like cyprinids. To gain insight into the physiological responses to oxygen fluctuations in two common cyprinid species, we evaluated the impact of short-term intermittent hypoxia on oxidative stress and metabolic parameters (including levels of prooxidants and oxidative lesions, antioxidants, mitochondrial enzyme activities, mitochondrial swelling, markers of apoptosis, autophagy and cytotoxicity) in silver carp Hypophthalmichthys molitrix and gibel carp Carassius gibelio. During hypoxia, gibel carp showed higher baseline levels of antioxidants and less pronounced changes in oxidative and metabolic biomarkers in the tissues than silver carp. Reoxygenation led to a strong shift in metabolic and redox-related parameters and tissue damage, indicating high cost of post-hypoxic recovery in both species. Species-specific differences were more strongly associated with oxidative stress status, whereas metabolic indices and nitrosative stress parameters were more relevant to the response to hypoxia-reoxygenation. Overall, regulation of energy metabolism appears more critical than the regulation of antioxidants in the response to oxygen deprivation in the studied species. Further research is needed to establish whether prioritizing metabolic over redox regulation during hypoxia-reoxygenation stress is common in freshwater cyprinids.

Thiopental sodium attenuates hypoxia/reoxygenation-induced injury in osteoblasts by modulating AKT signaling

Thiopental sodium (TPTS) is a barbiturate general anesthetic, while its effects on hypoxia/reoxygenation (H/R)-induced injury are still unclear. This study aimed to investigate whether TPTS exerts protective effects against the H/R-induced osteoblast cell injury and explore the underlying mechanisms. Osteoblast cell injury model was induced by the H/R condition, which was treated with or without TPTS. Cell viability and lactate dehydrogenase (LDH) release were determined by the corresponding commercial kits. The levels of oxidative stress were determined in the experimental groups. Cell apoptosis and Caspase-3 activities were determined by propidium iodide staining and substrate-based assay, respectively. Western blotting and qRT-PCR were performed to measure the mRNA and protein levels, respectively. Treatment with TPTS was able to increase cell viability and reduce LDH release in H/R-induced osteoblasts. Additionally, TPTS regulated oxidative stress in H/R-induced osteoblasts by suppressing malondialdehyde (MDA) and reactive oxygen species (ROS) as well as boosting superoxide dismutase (SOD). TPTS was able to suppress cell apoptosis by suppressing Caspase-3 activity and cleavage. TPTS exerted protective effects against cell injury and apoptosis induced by the H/R conditions, which were associated with its regulation of Akt signaling. Moreover, TPTS induced osteoblast differentiation under the H/R condition. In summary, TPTS attenuates H/R-induced injury in osteoblasts by regulating AKT signaling.

Release of High-Mobility Group Box-1 after a Raynaud's Attack Leads to Fibroblast Activation and Interferon-γ Induced Protein-10 Production: Role in Systemic Sclerosis Pathogenesis

Raynaud's Phenomenon (RP) leading to repetitive ischemia and reperfusion (IR) stress, is the first recognizable sign of systemic sclerosis (SSc) leading to increased oxidative stress. High-mobility group box-1 (HMGB1) is a nuclear factor released by apoptotic and necrotic cells after oxidative stress. Since HMGB1 can signal through the receptor for advanced glycation end products (RAGE), we investigated whether an RP attack promotes the release of HMGB1, leading to fibroblast activation and the upregulation of interferon (IFN)-inducible genes. A cold challenge was performed to simulate an RP attack in patients with SSc, primary RP (PRP), and healthy controls. We measured levels of HMGB1 and IFN gamma-induced Protein 10 (IP-10) at different time points in the serum. Digital perfusion was assessed by photoplethysmography. In vitro, HMGB1 or transforming growth factor (TGF-β1) (as control) was used to stimulate healthy human dermal fibroblasts. Inflammatory, profibrotic, and IFN-inducible genes, were measured by RT-qPCR. In an independent cohort, sera were obtained from 20 patients with SSc and 20 age- and sex-matched healthy controls to determine HMGB1 and IP-10 levels. We found that HMGB1 levels increased significantly 30 min after the cold challenge in SSc compared to healthy controls. In vitro stimulation with HMGB1 resulted in increased mRNA expression of IP-10, and interleukin-6 (IL-6) while TGF-β1 stimulation promoted IL-6 and Connective Tissue Growth Factor (CTGF). In serum, both HMGB1 and IP-10 levels were significantly higher in patients with SSc compared to healthy controls. We show that cold challenge leads to the release of HMGB1 in SSc patients. HMGB1 induces IP-10 expression in dermal fibroblasts partly through the soluble RAGE (sRAGE) axis suggesting a link between RP attacks, the release of HMGB1 and IFN-induced proteins as a putative early pathogenetic mechanism in SSc.

Metabolomics profiling to characterize cerebral ischemia-reperfusion injury in mice

Cerebral ischemia, resulting from compromised blood flow, is one of the leading causes of death worldwide with limited therapeutic options. Potential deleterious injuries resulting from reperfusion therapies remain a clinical challenge for physicians. This study aimed to explore the metabolomic alterations during ischemia-reperfusion injury by employing metabolomic analysis coupled with gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) and ultraperformance liquid chromatography quadrupole (UPLC/Q)-TOF-MS. Metabolomic data from mice subjected to middle cerebral artery occlusion (MCAO) followed by reperfusion (MCAO/R) were compared to those of the sham and MCAO groups. A total of 82 simultaneously differentially expressed metabolites were identified among each group. The top three major classifications of these differentially expressed metabolites were organic acids, lipids, and organooxygen compounds. Metabolomics pathway analysis was conducted to identify the underlying pathways implicated in MCAO/R. Based on impactor scores, the most significant pathways involved in the response to the reperfusion after cerebral ischemia were glycerophospholipid metabolism, linoleic acid metabolism, pyrimidine metabolism, and galactose metabolism. 17 of those 82 metabolites were greatly elevated in the MCAO/Reperfusion group, when compared to those in the sham and MCAO groups. Among those metabolites, glucose-6-phosphate 1, fructose-6-phosphate, cellobiose 2, o-phosphonothreonine 1, and salicin were the top five elevated metabolites in MCAO/R group, compared with the MCAO group. Glycolysis, the pentose phosphate pathway, starch and sucrose metabolism, and fructose and mannose degradation were the top four ranked pathways according to metabolite set enrichment analysis (MSEA). The present study not only advances our understanding of metabolomic changes among animals in the sham and cerebral ischemia groups with or without reperfusion via metabolomic profiling, but also paves the way to explore potential molecular mechanisms underlying metabolic alteration induced by cerebral ischemia-reperfusion.

Antioxidant and analgesic potential of butorphanol in dogs undergoing ovariohysterectomy

The aim of this study was to evaluate the postoperative analgesic and antioxidant effects of butorphanol given in the preoperative or early postoperative period. Twenty-seven healthy female dogs undergoing ovariohysterectomy were randomly divided into three groups as before surgery group (BSG, n = 7) received butorphanol 30 min before preanesthetic administration, after surgery group (ASG, n = 10) received butorphanol during the last skin suture and the control group (CG, n = 10) received no butorphanol. Pain was assessed with short form of the Glasgow composite pain scale (CMPS-SF). Serum concentration of malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase activities (GPx) were quantified by spectrophotometric methods to assess oxidative stress status. The pain score increased rapidly at 1 h after surgery and then decreased gradually towards to 24 h in all groups. There was no statistical difference among the groups in terms of CMPS-SF scores (P > 0.05). Serum concentration of MDA was lower in ASG than in BSG and CG from 1 h to 24 h after surgery. Serum activity of GPx was higher in ASG than in BSG and CG from 2 h to 24 h (P < 0.05). Serum activity of SOD was higher in ASG than in BSG and CG from 1 h to 24 h after surgery (P < 0.05). Serum SOD activity at different time points in ASG did not differ compared to preoperative level though it decreased significantly from 1 h onwards both in CT and BSG. The results indicate that single butorphanol administration either before or after the operation might not provide sufficient analgesia, however, it seems that it has antioxidant potential and may protect tissues by reducing oxidative stress when administered early postoperative period following ovariohysterectomy.

PCSK9 and Other Metabolic Targets to Counteract Ischemia/Reperfusion Injury in Acute Myocardial Infarction and Visceral Vascular Surgery

Ischemia/reperfusion (I/R) injury complicates both unpredictable events (myocardial infarction and stroke) as well as surgically-induced ones when transient clampage of major vessels is needed. Although the main cause of damage is attributed to mitochondrial dysfunction and oxidative stress, the use of antioxidant compounds for protection gave poor results when challenged in clinics. More recently, there is an assumption that, in humans, profound metabolic changes may prevail in driving I/R injury. In the present work, we narrowed the field of search to I/R injury in the heart/brain/kidney axis in acute myocardial infarction, major vascular surgery, and to the current practice of protection in both settings; then, to help the definition of novel strategies to be translated clinically, the most promising metabolic targets with their modulatory compounds—when available—and new preclinical strategies against I/R injury are described. The consideration arisen from the broad range of studies we have reviewed will help to define novel therapeutic approaches to ensure mitochondrial protection, when I/R events are predictable, and to cope with I/R injury, when it occurs unexpectedly.

Neuroprotective Effect of Piclamilast-Induced Post-Ischemia Pharmacological Treatment in Mice

Various studies have evidenced the neuroprotective role of PDE4 inhibitors. However, whether PDE4 inhibitor, Piclamilast pharmacological post-treatment is protective during cerebral ischemia reperfusion-induced injury remains unknown. Therefore, this study design included testing the hypothesis that Piclamilast administered at the beginning of a reperfusion phase (Piclamilast pPost-trt) shows protective effects and explores & probes underlying downstream mechanisms. Swiss albino male mice were subjected to global ischemic and reperfusion injury for 17 min. The animals examined cerebral infarct size, biochemical parameters, inflammatory mediators, and motor coordination. For memory, assessment mice were subjected to morris water maze (MWM) and elevated plus maze (EPM) test. Histological changes were assessed using HE staining. Piclamilast pPost-trt significantly reduced I/R injury-induced deleterious effects on biochemical parameters of oxidative stress, inflammatory parameters, infarct size, and histopathological changes, according to the findings. These neuroprotective effects of pPost-trt are significantly abolished by pre-treatment with selective CREB inhibitor, 666-15. Current study concluded that induced neuroprotective benefits of Piclamilast Post-trt, in all probability, maybe mediated through CREB activation. Hence, its neuroprotective effects can be further explored in clinical settings.

An Overview of the Molecular Mechanisms Associated with Myocardial Ischemic Injury: State of the Art and Translational Perspectives

Cardiovascular disease is the leading cause of death in western countries. Among cardiovascular diseases, myocardial infarction represents a life-threatening condition predisposing to the development of heart failure. In recent decades, much effort has been invested in studying the molecular mechanisms underlying the development and progression of ischemia/reperfusion (I/R) injury and post-ischemic cardiac remodeling. These mechanisms include metabolic alterations, ROS overproduction, inflammation, autophagy deregulation and mitochondrial dysfunction. This review article discusses the most recent evidence regarding the molecular basis of myocardial ischemic injury and the new potential therapeutic interventions for boosting cardioprotection and attenuating cardiac remodeling.

Xanthohumol Protects the Rat Myocardium against Ischemia/Reperfusion Injury-Induced Ferroptosis

Ferroptosis is an iron-dependent form of cell death caused by the inactivation of glutathione peroxidase 4 (GPX4) and accumulation of lipid peroxides. Ferroptosis has been found to participate in the ischemia-reperfusion (I/R) injury, leading to heart dysfunction and myocardial cell death. Xanthohumol (XN), a prenylated flavonoid isolated from Humulus lupulus, has multiple pharmacological activities, such as anti-inflammatory and antioxidant. This study is aimed at investigating whether XN could attenuate the I/R-induced ferroptosis in cardiomyocytes and the underlying mechanisms. Cardiomyocytes were treated with Fe-SP and RSL3, and the rat hearts were treated with I/R. The results from the present study show that XN was able to protect cardiomyocytes against Fe-SP- and RSL3-induced ferroptotic cell death by decreasing the production of lipid peroxidation and ROS, chelating iron, reducing the NRF2 protein level, and modulating the protein levels of GPX4. Moreover, XN significantly decreased the mRNA levels of ferroptosis markers, Ptgs2 and Acsl4, and the protein levels of ACSL4 and NRF2 and modulated the protein levels of GPX4 in I/R-treated hearts. The findings from the present study suggest that XN might have the therapeutic potential for the I/R-induced ferroptosis injury.

Renal Ischemia/Reperfusion Early Induces Myostatin and PCSK9 Expression in Rat Kidneys and HK-2 Cells

During visceral interventions, the transient clampage of supraceliac aorta causes ischemia/reperfusion (I/R) in kidneys, sometime resulting in acute renal failure; preclinical studies identified redox imbalance as the main driver of I/R injury. However, in humans, the metabolic/inflammatory responses seem to prevail on oxidative stress. We investigated myostatin (Mstn) and proprotein convertase subtilisin/kexin type 9 (PCSK9), proatherogenic mediators, during renal I/R. Compared to sham-operated animals, the kidneys of rats who had experienced ischemia (30 min) had higher Mstn and PCSK9 expression after 4 h of reperfusion. After 24 h, they displayed tubular necrosis, increased nitrotyrosine positivity, and nuclear peroxisome proliferator-activated receptor gamma coactivator-1alpha relocation, markers of oxidative stress and mitochondria imbalance. Mstn immunopositivity was increased in tubuli, while PCSK9 immunosignal was depleted; systemically, PCSK9 was higher in plasma from I/R rats. In HK-2 cells, both ischemia and reperfusion enhanced reactive oxygen species production and mitochondrial dysfunction. H₂O₂ upregulated Mstn and PCSK9 mRNA after 1 and 3.5 h, respectively. Accordingly, ischemia early induced Mstn and PCSK9 mRNA; during reperfusion Mstn was augmented and PCSK9 decreased. Mstn treatment early increased PCSK9 expression (within 8 h), to diminish over time; finally, Mstn silencing restrained ischemia-induced PCSK9. Our study demonstrates that renal I/R enhances Mstn and PCSK9 expression and that Mstn induces PCSK9, suggesting them as therapeutic targets for vascular protection during visceral surgery.

Renal Delivery of Pharmacologic Agents During Machine Perfusion to Prevent Ischaemia-Reperfusion Injury: From Murine Model to Clinical Trials

Donor organ shortage still remains a serious obstacle for the access of wait-list patients to kidney transplantation, the best treatment for End-Stage Kidney Disease (ESKD). To expand the number of transplants, the use of lower quality organs from older ECD or DCD donors has become an established routine but at the price of increased incidence of Primary Non-Function, Delay Graft Function and lower-long term graft survival. In the last years, several improvements have been made in the field of renal transplantation from surgical procedure to preservation strategies. To improve renal outcomes, research has focused on development of innovative and dynamic preservation techniques, in order to assess graft function and promote regeneration by pharmacological intervention before transplantation. This review provides an overview of the current knowledge of these new preservation strategies by machine perfusions and pharmacological interventions at different timing possibilities: in the organ donor, ex-vivo during perfusion machine reconditioning or after implementation in the recipient. We will report therapies as anti-oxidant and anti-inflammatory agents, senolytics agents, complement inhibitors, HDL, siRNA and H2S supplementation. Renal delivery of pharmacologic agents during preservation state provides a window of opportunity to treat the organ in an isolated manner and a crucial route of administration. Even if few studies have been reported of transplantation after ex-vivo drugs administration, targeting the biological pathway associated to kidney failure (i.e. oxidative stress, complement system, fibrosis) might be a promising therapeutic strategy to improve the quality of various donor organs and expand organ availability.

Dexmedetomidine inhibits inflammatory response and oxidative stress through regulating miR-205-5p by targeting HMGB1 in cerebral ischemic/reperfusion

OBJECTIVE

To investigate effects of dexmedetomidine (DEX) on miR-205-5p/HMGB1 axis in cerebral ischemic/reperfusion (I/R) injury.

METHODS

Both in vivo I/R rat model and in vitro hypoxia/reoxygenation (H/R) cell model using rat hippocampal neurons cells were established. miR-205-5p was overexpressed or inhibited by transfection of miR-205-5p mimics or inhibitor. HMGB1 was overexpressed by transfection overexpression plasmids (OE-HMGB1). TTC staining was used for measurement of infraction volume. Oxidative stress was evaluated by measurement of reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) and inflammation was evaluated by measurement of IL-1β, IL-6 and TNF-α. Dual luciferase reporter assay was performed to confirm binding between miR-205-5p and HMGB1. The expression levels of miR-205-5p, and HMGB1 were measured using RT-qPCR. Western blotting was used to test the protein expression levels of HMGB1, nuclear factor erythroid 2-related factor 2 (Nrf2), glutathione peroxidase (GPx), glutathione reductase (GR), heme oxygenase 1 (HO-1) and catalase (CAT).

RESULTS

Treatment of DEX significantly reduced brain infraction volume, decreased Longa's neurological function score and inhibited oxidative stress and inflammation in brain tissues of I/R rats, which were all reversed by inhibition of miR-205-5p. Both treatment of DEX or overexpression of miR-205-5p restricted oxidative stress and inflammation in H/R rat hippocampal neurons cells. The inhibition of miR-205-5p reversed the effects of DEX, while the overexpression of HMGB1 reversed the effects of miR-205-5p overexpression in H/R rat hippocampal neurons cells. Dual luciferase reporter assay showed miR-205-5p directly targeted HMGB1.

CONCLUSION

DEX improved I/R injury by suppressing brain oxidative stress and inflammation DEX improved I/R injury by suppressing brain oxidative stress and inflammation through activating miR-205-5p/HMGB1 axis through activating miR-205-5p/HMGB1 axis.

Nanozyme Impregnated Mesenchymal Stem Cells for Hepatic Ischemia-Reperfusion Injury Alleviation

Mesenchymal stem cell (MSC) based therapy holds great potential for treating numerous diseases owing to their capability to heal injured tissue/organs through paracrine factors secretion and immunomodulation. Despite the high hopes, the low viability of transplanted cells in the injured tissues due to the elevated oxidative stress levels remains the largest obstacle in MSC-based cell therapy. To achieve desired therapeutic efficiency, the survival of the transplanted MSCs in the high oxidative stress environment needs to be ensured. Herein, we proposed the use of a ROS-scavenging nanozyme to protect transplanted MSCs from oxidative stress-mediated apoptosis and thereby improve the therapeutic effect. Prussian blue (PB) nanoparticles as a biocompatible ROS-scavenging nanozyme were incorporated into the MSCs without affecting the stemness and differentiation potential of MSCs. The nanozyme impregnation significantly improved the survival of MSCs in a high oxidative stress condition as well as augmented their paracrine effect and anti-inflammatory properties, resulting in a profound therapeutic effect in vivo in the liver ischemia-reperfusion (I/R) injury animal model. Our results indicated that the nanozyme incorporation into MSCs is a simple but efficient way to improve the therapeutic potential of MSC-based cell therapy.

The Endothelial Glycocalyx as a Target of Ischemia and Reperfusion Injury in Kidney Transplantation-Where Have We Gone So Far?

The damage of the endothelial glycocalyx as a consequence of ischemia and/or reperfusion injury (IRI) following kidney transplantation has come at the spotlight of research due to potential associations with delayed graft function, acute rejection as well as long-term allograft dysfunction. The disintegration of the endothelial glycocalyx induced by IRI is the crucial event which exposes the denuded endothelial cells to further inflammatory and oxidative damage. The aim of our review is to present the currently available data regarding complex links between shedding of the glycocalyx components, like syndecan-1, hyaluronan, heparan sulphate, and CD44 with the activation of intricate immune system responses, including toll-like receptors, cytokines and pro-inflammatory transcription factors. Evidence on modes of protection of the endothelial glycocalyx and subsequently maintenance of endothelial permeability as well as novel nephroprotective molecules such as sphingosine-1 phosphate (S1P), are also depicted. Although advances in technology are making the visualization and the analysis of the endothelial glycocalyx possible, currently available evidence is mostly experimental. Ongoing progress in understanding the complex impact of IRI on the endothelial glycocalyx, opens up a new era of research in the field of organ transplantation and clinical studies are of utmost importance for the future.

Anti-IL-20 Antibody Protects against Ischemia/Reperfusion-Impaired Myocardial Function through Modulation of Oxidative Injuries, Inflammation and Cardiac Remodeling

Acute myocardial infarction (AMI) is the most critical event in the disease spectrum of coronary artery disease. To rescue cardiomyocytes in AMI, it is important to restore blood supply as soon as possible to reduce ischemia-induced injury. However, worse damage can occur during the reperfusion phase, called the reperfusion injury. Under ischemia/reperfusion (I/R) injury, elevated oxidative stress plays a critical role in regulation of apoptosis, inflammation and remodeling of myocardium. Our previous study has demonstrated that interleukin (IL)-20 is increased during hypoxia/reoxygenation stimulation and promotes apoptosis in cardiomyocytes. This study was, therefore, designed to investigate whether IL-20 antibody could reduce I/R-induced myocardial dysfunction. Results from this study revealed that IL-20 antibody treatment significantly suppressed I/R-induced nicotinamide adenine dinucleotide phosphate oxidase, oxidative stress, apoptosis, proinflammatory responses, cardiac fibrosis, and expression of cardiac remodeling markers in Sprague-Dawley rats. Plasma B-type natriuretic peptide level was also reduced by IL-20 antibody injection. IL-20 antibody treatment appeared to restore cardiac function under the I/R injury in terms of greater values of ejection fraction and fractional shortening compared to the control group. Two commonly used indicators of cardiac injury, lactate dehydrogenase and creatine kinase-MB, were also lower in the IL-20 antibody injection group. Taken together, our results suggested that IL-20 antibody holds the potential to reduce the I/R-elicited cardiac dysfunction by preventing cardiac remodeling.

Discovery of new therapeutic redox targets for cardioprotection against ischemia/reperfusion injury and heart failure

Global epidemiological studies reported a shift from maternal/infectious communicable diseases to chronic non-communicable diseases and a major part is attributable to atherosclerosis and metabolic disorders. Accordingly, ischemic heart disease was identified as a leading risk factor for global mortality and morbidity with a prevalence of 128 million people. Almost 9 million premature deaths can be attributed to ischemic heart disease and subsequent acute myocardial infarction and heart failure, also representing a substantial socioeconomic burden. As evidenced by typical oxidative stress markers such as lipid peroxidation products or oxidized DNA/RNA bases, the formation of reactive oxygen species by various sources (NADPH oxidases, xanthine oxidase and mitochondrial resperatory chain) plays a central role for the severity of ischemia/reperfusion damage. The underlying mechanisms comprise direct oxidative damage but also adverse redox-regulation of kinase and calcium signaling, inflammation and cardiac remodeling among others. These processes and the role of reactive oxygen species are discussed in the present review. We also present and discuss potential targets for redox-based therapies that are either already established in the clinics (e.g. guanylyl cyclase activators and stimulators) or at least successfully tested in preclinical models of myocardial infarction and heart failure (mitochondria-targeted antioxidants). However, reactive oxygen species have not only detrimental effects but are also involved in essential cellular signaling and may even act protective as seen by ischemic pre- and post-conditioning or eustress - which makes redox therapy quite challenging.

Oxygen-release microspheres capable of releasing oxygen in response to environmental oxygen level to improve stem cell survival and tissue regeneration in ischemic hindlimbs

Stem cell transplantation has been extensively explored to promote ischemic limb vascularization and skeletal muscle regeneration. Yet the therapeutic efficacy is low due to limited cell survival under low oxygen environment of the ischemic limbs. Therefore, continuously oxygenating the transplanted cells has potential to increase their survival. During tissue regeneration, the number of blood vessels are gradually increased, leading to the elevation of tissue oxygen content. Accordingly, less exogenous oxygen is needed for the transplanted cells. Excessive oxygen may induce reactive oxygen species (ROS) formation, causing cell apoptosis. Thus, it is attractive to develop oxygen-release biomaterials that are responsive to the environmental oxygen level. Herein, we developed oxygen-release microspheres whose oxygen release was controlled by oxygen-responsive shell. The shell hydrophilicity and degradation rate decreased as the environmental oxygen level increased, leading to slower oxygen release. The microspheres were capable of directly releasing molecular oxygen, which are safer than those oxygen-release biomaterials that release hydrogen peroxide and rely on its decomposition to form oxygen. The released oxygen significantly enhanced mesenchymal stem cell (MSC) survival without inducing ROS production under hypoxic condition. Co-delivery of MSCs and microspheres to the mouse ischemic limbs ameliorated MSC survival, proliferation and paracrine effects under ischemic conditions. It also significantly accelerated angiogenesis, blood flow restoration, and skeletal muscle regeneration without provoking tissue inflammation. The above results demonstrate that the developed microspheres have potential to augment cell survival in ischemic tissues, and promote ischemic tissue regeneration in a safer and more efficient manner.

Lipid Peroxidation in Atherosclerotic Cardiovascular Diseases

Significance: Atherosclerotic cardiovascular diseases (ACVDs) continue to be a primary cause of mortality worldwide in adults aged 35-70 years, occurring more often in countries with lower economic development, and they constitute an ever-growing global burden that has a considerable socioeconomic impact on society. The ACVDs encompass diverse pathologies such as coronary artery disease and heart failure (HF), among others. Recent Advances: It is known that oxidative stress plays a relevant role in ACVDs and some of its effects are mediated by lipid oxidation. In particular, lipid peroxidation (LPO) is a process under which oxidants such as reactive oxygen species attack unsaturated lipids, generating a wide array of oxidation products. These molecules can interact with circulating lipoproteins, to diffuse inside the cell and even to cross biological membranes, modifying target nucleophilic sites within biomolecules such as DNA, lipids, and proteins, and resulting in a plethora of biological effects. Critical Issues: This review summarizes the evidence of the effect of LPO in the development and progression of atherosclerosis-based diseases, HF, and other cardiovascular diseases, highlighting the role of protein adduct formation. Moreover, potential therapeutic strategies targeted at lipoxidation in ACVDs are also discussed. Future Directions: The identification of valid biomarkers for the detection of lipoxidation products and adducts may provide insights into the improvement of the cardiovascular risk stratification of patients and the development of therapeutic strategies against the oxidative effects that can then be applied within a clinical setting.

Are Reactive Sulfur Species the New Reactive Oxygen Species?

Significance: Oxidative stress in moderation positively affects homeostasis through signaling, while in excess it is associated with adverse health outcomes. Both activities are generally attributed to reactive oxygen species (ROS); hydrogen peroxide as the signal, and cysteines on regulatory proteins as the target. However, using antioxidants to affect signaling or benefit health has not consistently translated into expected outcomes, or when it does, the mechanism is often unclear. Recent Advances: Reactive sulfur species (RSS) were integral in the origin of life and throughout much of evolution. Sophisticated metabolic pathways that evolved to regulate RSS were easily "tweaked" to deal with ROS due to the remarkable similarities between the two. However, unlike ROS, RSS are stored, recycled, and chemically more versatile. Despite these observations, the relevance and regulatory functions of RSS in extant organisms are generally underappreciated. Critical Issues: A number of factors bias observations in favor of ROS over RSS. Research conducted in room air is hyperoxic to cells, and promotes ROS production and RSS oxidation. Metabolic rates of rodent models greatly exceed those of humans; does this favor ROS? Analytical methods designed to detect ROS also respond to RSS. Do these disguise the contributions of RSS? Future Directions: Resolving the ROS/RSS issue is vital to understand biology in general and human health in particular. Improvements in experimental design and analytical methods are crucial. Perhaps the most important is an appreciation of all the attributes of RSS and keeping an open mind.

Systemic and sustained thioredoxin analogue prevents acute kidney injury and its-associated distant organ damage in renal ischemia reperfusion injury mice

The mortality of patients with acute kidney injury (AKI) remains high due to AKI associated-lung injury. An effective strategy for preventing both AKI and AKI-associated lung injury is urgently needed. Thioredoxin-1 (Trx) is a redox-active protein that possesses anti-oxidative, anti-apoptotic and anti-inflammatory properties including modulation of macrophage migration inhibitory factor (MIF), but its short half-life limits its clinical application. Therefore, we examined the preventive effect of a long-acting Trx, which is a fusion protein of albumin and Trx (HSA-Trx), against AKI and AKI-associated lung injury. Recombinant HSA-Trx was expressed using a Pichia expression system. AKI-induced lung injury mice were generated by bilateral renal ischemia reperfusion injury (IRI). HSA-Trx administration attenuated renal IRI and its-associated lung injury. Both renal and pulmonary oxidative stress were suppressed by HSA-Trx. Moreover, HSA-Trx inhibited elevations of plasma IL-6 and TNF-α level, and suppressed IL-6-CXCL1/2-mediated neutrophil infiltration into lung and TNF-α-mediated pulmonary apoptosis. Additionally, HSA-Trx suppressed renal IRI-induced MIF expression in kidney and lung. Administration of HSA-Trx resulted in a significant increase in the survival rate of renal IRI mice. Collectively, HSA-Trx could have therapeutic utility in preventing both AKI and AKI-associated lung injury as a consequence of its systemic and sustained multiple biological action.

Prokineticin 2 relieves hypoxia/reoxygenation-induced injury through activation of Akt/mTOR pathway in H9c2 cardiomyocytes

Prokineticin 2 (PK2) was reported to be decreased in the hearts of end-state heart failure patients. Our study aimed to explore the effects of PK2 on hypoxia/reoxygenation (H/R) injury and the underlying mechanism. H9c2 cardiomyocytes were treated with 5 nM PK2 in the presence or absence of 5 mM dual phosphatidylinositol 3-kinase (PI3K)/the mammalian target of rapamycin (mTOR) inhibitor (BEZ235) for 24 h and then subjected to H/R treatment. Cell viability and lactate dehydrogenase (LDH) release were evaluated by CCK-8 and LDH release assays, respectively. Apoptosis was determined by flow cytometry analysis. Oxidative stress was assessed by measuring superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA) content. Results showed that H/R treatment decreased PK2 expression and inactivated the Akt/mTOR pathway in H9c2 cardiomyocytes. PK2 treatment activated the Akt/mTOR pathway in H/R-exposed H9c2 cardiomyocytes. H/R stimulation suppressed cell viability, increased LDH release, induced apoptosis and oxidative stress in H9c2 cardiomyocytes, while these effects were neutralised by treatment with PK2. However, the inhibitory effects of PK2 on H/R-induced injury in H9c2 cardiomyocytes were abolished by the addition of BEZ235. In conclusion, PK2 relieved H/R-induced injury in H9c2 cardiomyocytes by activation of the Akt/mTOR pathway.

Assessment of Hand Motor Function in a Non-human Primate Model of Ischemic Stroke

Ischemic stroke results from arterial occlusion and can cause irreversible brain injury. A non-human primate (NHP) model of ischemic stroke was previously developed to investigate its pathophysiology and for efficacy testing of therapeutic candidates; however, fine motor impairment remains to be well-characterized. We evaluated hand motor function in a cynomolgus monkey model of ischemic stroke. Endovascular transient middle cerebral artery occlusion (MCAO) with an angiographic microcatheter induced cerebral infarction. In vivo magnetic resonance imaging mapped and measured the ischemia-induced infarct lesion. In vivo diffusion tensor imaging (DTI) of the stroke lesion to assess the neuroplastic changes and fiber tractography demonstrated three-dimensional patterns in the corticospinal tract 12 weeks after MCAO. The hand dexterity task (HDT) was used to evaluate fine motor movement of upper extremity digits. The HDT was modified for a home cage-based training system, instead of conventional chair restraint training. The lesion was localized in the middle cerebral artery territory, including the sensorimotor cortex. Maximum infarct volume was exhibited over the first week after MCAO, which progressively inhibited ischemic core expansion, manifested by enhanced functional recovery of the affected hand over 12 weeks after MCAO. The total performance time decreased with increasing success rate for both hands on the HDT. Compensatory strategies and retrieval failure improved in the chronic phase after stroke. Our findings demonstrate the recovery of fine motor skill after stroke, and outline the behavioral characteristics and features of functional disorder of NHP stroke model, providing a basis for assessing hand motor function after stroke.

Transplanted Kidney Increases Nitric Oxide Formation With Metabolic Acidosis Reduction

OBJECTIVES

As a vasodilator, nitric oxide is considered to play a significant role in the homeostatic regulation of renal hemodynamics. To test the hypothesis that a kidney graft is capable of producing nitric oxide immediately after renal transplant surgery, we examined the possibility that it positively affects local metabolic acidosis.

MATERIALS AND METHODS

In kidney transplant recipients, we analyzed renal vein and central vein blood samples, which reflect local and systemic metabolic alterations, respectively. Samples were taken immediately after kidney recirculation (that is, the first blood passing through after clamps are released) and at 5, 15, and 30 minutes thereafter. Levels of nitric oxide metabolites (nitrites, nitrates, and their sum), malondialdehyde (an indicator of oxidative damages), and parameters of acid-base balance (pH level, actual excess base, hemoglobin, actual bicarbonate, partial pressure of carbon dioxide, partial pressure of oxygen) were analyzed. Living kidney donors (the recipients' parents) were controls.

RESULTS

In renal vein samples, nitrates and the sum of nitrites and nitrates were significantly higher than that shown in control (P < .001) and central vein (P < .05) samples, suggesting an immediate increase in nitric oxide production in the transplanted organ. Metabolic acidosis occurred in both the renal and central vein, indicated by decreased pH and actual bicarbonate level as well as by negative actual base excess level. Only in the renal vein was an increased nitrite and nitrate associated with a reduction of negative actual excess base, thereby suggesting a decrease in anion formation.

CONCLUSIONS

Transplanted kidneys increase nitric oxide production immediately after organ transplant surgery, which positively affects local metabolic acidosis. The mechanism for this effect is likely local circulation improvement.

Therapeutic effects of syringaldehyde on spinal cord ischemia in rabbits

OBJECTIVES

To investigate the effects of syringaldehyde (SA) on the antioxidant and oxidant system in spinal cord ischemia (SCI).

METHODS

These study and experiments were conducted at Medical Research Center, Çanakkale Onsekiz Mart University, Çanakkale, Turkey, between 2014-2018. Eighteen New Zealand White adult male rabbits were randomly divided into 3 groups (n=6). Superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), myeloperoxidase (MPO) activities, and malondialdehyde (MDA) levels were measured in the spinal cord tissues. Degenerated neurons, hemorrhage and in ammatory cell migration in the spinal cord were investigated histopathologically. Expressions of neuronal nitric oxide synthase (nNOS), caspase-3, and nuclear factor-κB (NF-κB) were evaluated immunohistochemically. Clinically, it was evaluated with modified Tarlov score.

RESULTS

Biochemically, there was an expected decrease in SOD, CAT, and GPx enzyme activities in ischemia groups, there was also an increase in MPO activity at the same time. When the enzyme activities spinal cord ischemia/ reperfusion (SCI/R)+SA, control and SCI/R groups were compared, the difference was found to be statistically significant (p less than 0.05). Glutathione peroxidase enzyme activity levels were very low in ischemia group compared to the significant increase in the SA group (p less than 0.05). Histopathologically, when SCI/R and SCI/R+SA groups were compared, there were statistically significant differences in the number of degenerative neurons and amount of hemorrhage; this comparison shows the significance of treatment in terms of inflammatory cell migration (p less than 0.05). The expressions of nNOS, caspase-3, and NF-κB were found significantly increased in SCI/R group compared to the control group (p less than 0.05). Syringaldehyde treatment decreased nNOS, caspase-3, and NF-κB expressions immunohistochemically. Clinical evaluation showed improvement in the SA-treated group.

CONCLUSION

Syringaldehyde therapy administered for protective purposes may reduce oxidative stress, degenerative changes and in ammatory cell migration in the ischemic spinal cord.Saudi Med J 2020; Vol. 41 (4): 341-350doi: 10.15537/smj.2020.4.24993 How to cite this article:Malçok UA,  Aras AB, Şehitoğlu MH, Akman T, Yüksel Y. Therapeutic effects of syringaldehyde on spinal cord ischemia in rabbits. Saudi Med J 2020; Vol. 41: 341-350. doi: 10.15537/smj.2020.4.24993.

Neuroprotective effect of menaquinone-4 (MK-4) on transient global cerebral ischemia/reperfusion injury in rat

Cerebral ischemia/reperfusion (I/R) injury causes cognitive deficits, excitotoxicity, neuroinflammation, oxidative stress and brain edema. Vitamin K2 (Menaquinone 4, MK-4) as a potent antioxidant can be a good candidate to ameliorate I/R consequences. This study focused on the neuroprotective effects of MK-4 for cerebral I/R insult in rat’s hippocampus. The rat model of cerebral I/R was generated by transient bilateral common carotid artery occlusion for 20 min. Rats were divided into control, I/R, I/R+DMSO (solvent (1% v/v)) and I/R+MK-4 treated (400 mg/kg, i.p.) groups. Twenty-four hours after I/R injury induction, total brain water content, superoxide dismutase (SOD) activity, nitrate/nitrite concentration and neuronal density were evaluated. In addition to quantify the apoptosis processes, TUNEL staining, as well as expression level of Bax and Bcl2, were assessed. To evaluate astrogliosis and induced neurotoxicity by I/R GFAP and GLT-1 mRNA expression level were quantified. Furthermore, pro-inflammatory cytokines including IL-1β, IL-6 and TNF-α were measured. Seven days post I/R, behavioral analysis to quantify cognitive function, as well as Nissl staining for surviving neuronal evaluation, were conducted. The findings indicated that administration of MK-4 following I/R injury improved anxiety-like behavior, short term and spatial learning and memory impairment induced by I/R. Also, MK-4 was able to diminish the increased total brain water content, apoptotic cell density, Bax/ Bcl2 ratio and GFAP mRNA expression following I/R. In addition, the high level of nitrate/nitrite, IL-6, IL-1β and TNF-α induced by I/R was reduced after MK-4 administration. However, MK-4 promotes the level of SOD activity and GLT-1 mRNA expression in I/R rat model. The findings demonstrated that MK-4 can rescue transient global cerebral I/R consequences via its anti-inflammatory and anti-oxidative stress features. MK-4 administration ameliorates neuroinflammation, neurotoxicity and neuronal cell death processes and leads to neuroprotection.

Inhibition of miR-153 ameliorates ischemia/reperfusion-induced cardiomyocytes apoptosis by regulating Nrf2/HO-1 signaling in rats

Background

Previous in vitro studies demonstrated that suppression of microRNAs might protect cardiomyocytes and neurons against oxygen–glucose deprivation and reoxygenation (OGD/R)-induced cell apoptosis. However, whether the protective effect of miR-153-inhibition on cardiomyocytes can be observed in the animal model is unknown. We aimed to address this question using a rat model of ischemia–reperfusion (I/R).

Methods

Rats were received the intramyocardial injection of saline or adenovirus-carrying target or control gene, and the rats were subjected to ischemia/reperfusion (I/R) treatment. The effects of miR-153 on I/R-induced inflammatory response and oxidative stress in the rat model were assessed using various assays.

Results

We found that suppression of miR-153 decreased cleaved caspase-3 and Bcl-2-associated X (Bax) expression, and increased B cell lymphoma 2 (Bcl-2) expression. We further confirmed that Nuclear transcription factor erythroid 2-like 2 (Nrf2) is a functional target of miR-153, and Nrf2/Heme oxygenase-1 (HO-1) signaling was involved in miR-153-regulated I/R-induced cardiomyocytes apoptosis. Inhibition of miR-153 reduced I/R-induced inflammatory response and oxidative stress in rat myocardium.

Conclusion

Suppression of miR-153 exerts a cardioprotective effect against I/R-induced injury through the regulation of Nrf2/HO-1 signaling, suggesting that targeting miR-153, Nrf2, or both may serve as promising therapeutic targets for the alleviation of I/R-induced injury.

Reactive oxygen species or reactive sulfur species: why we should consider the latter

The biological effects of oxidants, especially reactive oxygen species (ROS), include signaling functions (oxidative eustress), initiation of measures to reduce elevated ROS (oxidative stress), and a cascade of pathophysiological events that accompany excessive ROS (oxidative distress). Although these effects have long been studied in animal models with perturbed ROS, their actions under physiological conditions are less clear. I propose that some of the apparent uncertainty may be due to confusion of ROS with endogenously generated reactive sulfur species (RSS). ROS and RSS are chemically similar, but RSS are more reactive and versatile, and can be stored and reused. Both ROS and RSS signal via oxidation reactions with protein cysteine sulfur and they produce identical effector responses, but RSS appear to be more effective. RSS in the form of persulfidated cysteines (Cys-S-S) are produced endogenously and co-translationally introduced into proteins, and there is increasing evidence that many cellular proteins are persulfidated. A number of practical factors have contributed to confusion between ROS and RSS, and these are discussed herein. Furthermore, essentially all endogenous antioxidant enzymes appeared shortly after life began, some 3.8 billion years ago, when RSS metabolism dominated evolution. This was long before the rise in ROS, 600 million years ago, and I propose that these same enzymes, with only minor modifications, still effectively metabolize RSS in extant organisms. I am not suggesting that all ROS are RSS; however, I believe that the relative importance of ROS and RSS in biological systems needs further consideration.

Transplantation of viable mitochondria attenuates neurologic injury after spinal cord ischemia

OBJECTIVES

Spinal cord ischemia (SCI) is one of the major concerns of postoperative paraplegia during major vascular or aortic surgery. Since mitochondrial dysfunction develops at the early stage of SCI, this study tested the neuronal protective effect of transplantation of viable mitochondria to the ischemic cord in rats.

METHODS

SCI was induced by crossclamping of thoracic aorta at T6 level for 25 minutes, followed by release of vascular clip to restore aortic blood flow in the anesthetized rats. Mitochondria (100 μg) were isolated from freshly harvested soleus muscle and delivered via the internal jugular vein before releasing of vascular clip. The motor function was assessed independently up to 7 days after reperfusion. Spinal cords were harvested and analyzed for molecular and histological changes.

RESULTS

Whole-body in vivo images acquired by an in vivo imaging system confirmed the enhancement of MitoTracker fluorescence at the regions below crossclamping and in the ischemic cord. Compared with control vehicles, transplantation of mitochondria significantly improved the lower-limb locomotor function of rats subjected to cord ischemia up to 7 days after surgery. Mitochondrial transplantation suppressed the regional endoplasmic reticulum stress in the ischemic cord by attenuating CCAAT-enhancer-binding protein homologous protein expression and restoring binding immunoglobulin protein levels. In accordance, tissue levels of interleukin-6, tumor necrosis factor-α, and caspase-3 were attenuated in the mitochondrial transplanted group. Histologic examination also showed significant increase in numbers of Nissls bodies in the neurons at the ventral horn of ischemic cord following mitochondrial transplantation.

CONCLUSIONS

Our study showed that transplantation of freshly isolated mitochondria during the early stage of spinal cord ischemia-reperfusion injury suppressed the oxidative stress in endoplasmic reticulum of the injured cord, thereby reducing neuroapoptosis and improving locomotor function of rats with SCI.

Effect of moxibustion preconditioning on autophagy-related proteins in rats with myocardial ischemia reperfusion injury

Background

Autophagy has increasingly been recognized as playing an essential role in the pathogenesis of myocardial ischemia reperfusion injury (MIRI). Moxibustion, a form of heat therapy commonly used in traditional Chinese medicine (TCM), has been shown to exhibit cardioprotective effects. However, whether the cardioprotective effect of moxibustion is related to the regulation of autophagy remains unknown. This study aimed to investigate the possible mechanism underlying the cardioprotective effect of moxibustion preconditioning at PC6 on MIRI by measuring the expressions of proteins involved in the regulation of autophagy.

Methods

Male Sprague-Dawley rats were randomly divided to receive moxibustion preconditioning or autophagy inhibitor 3-Methyladenine (3-MA) intervention. Then the MIRI model was established by ligating the left anterior descending (LAD) coronary artery for 30 minutes followed by reperfusion for 4 hours. After 4 hours of reperfusion, the myocardial infarction area was assessed using Evans blue and TTC staining, and cTnT and lactate dehydrogenase (LDH) levels in the serum were determined by ELISA. Hematoxylin and eosin (H&E) staining was performed for morphological evaluation of ventricular tissues. Expressions of autophagy components Beclin 1, Bcl-2, and Akt were assessed using quantitative real-time PCR, immunohistochemistry (IHC) and western blot.

Results

Moxibustion preconditioning significantly reduced the necrotic area and the levels of cTnT and LDH were similar to the 3-MA intervention, also attenuated morphological alterations were induced by MIRI. Simultaneously, the mRNA and protein expressions of Beclin 1 and Akt were up-regulated, while those of Bcl-2 were down-regulated by MIRI. Moxibustion preconditioning and 3-MA intervention reversed MIRI-induced changes in Beclin 1, Akt, and Bcl-2 expressions.

Conclusions

Moxibustion preconditioning at PC6 can attenuate myocardial injury for MIRI in a similar way to 3-MA intervention. This cardioprotective effect of moxibustion preconditioning may be mediated by modulating autophagy via regulation of Beclin 1, Bcl-2 and Akt.

Effects of resveratrol postconditioning on cerebral ischemia in mice: role of the sirtuin-1 pathway

Evidence has demonstrated that resveratrol preconditioning exhibits neuroprotection against cerebral ischemia-reperfusion (IR) injury. The current investigation aimed to explore whether pharmacological postconditioning, by administering resveratrol, after a sustained ischemia and prior to prolonged reperfusion abrogates cerebral IR injury. Cerebral IR-induced injury mice model was employed in this study to evaluate the neuroprotective effects of pharmacological postconditioning with resveratrol (30 mg/kg; i.p.) administered 5 min before reperfusion. We administered sirtinol, a SIRT1/2 selective inhibitor (10 mg/kg; i.p.) 10 min before ischemia (17 min) and reperfusion (24 h), to elucidate whether the neuroprotection with resveratrol postconditioning depends on SIRT1 activation. Various biochemical and behavioural parameters and histopathological changes were assessed to examine the effect of pharmacological postconditioning. Infarct size is estimated using TTC staining. It was established that resveratrol postconditioning abrogated the deleterious effects of IR injury expressed with regard to biochemical parameters of oxidative stress (TBARS, SOD, GSH), acetylcholinesterase activity, behavioural parameters (memory, motor coordination), infarct size, and histopathological changes. Sirtinol significantly reversed the effect of resveratrol postconditioning. We conclude that induced neuroprotective benefits of resveratrol postconditioning may be the consequence of SIRT1 activation and resveratrol can be considered, for further studies, as potential agent inducing pharmacological postconditioning in clinical situations.

Oxidative stress and antioxidant treatment in patients with peripheral artery disease

Peripheral artery disease is an atherosclerotic disease of arterial vessels that mostly affects arteries of lower extremities. Effort induced cycles of ischemia and reperfusion lead to increased reactive oxygen species production by mitochondria. Therefore, the pathophysiology of peripheral artery disease is a consequence of metabolic myopathy, and oxidative stress is the putative major operating mechanism behind the structural and metabolic changes that occur in muscle. In this review, we discuss the evidence for oxidative damage in peripheral artery disease and discuss management strategies related to antioxidant supplementation. We also highlight the major pathways governing oxidative stress in the disease and discuss their implications in disease progression. Potential therapeutic targets and diagnostic methods related to these mechanisms are explored, with an emphasis on the Nrf2 pathway.

TXNIP knockdown alleviates hepatocyte ischemia reperfusion injury through preventing p38/JNK pathway activation

Hepatic ischemia and reperfusion (I/R) injury is a major cause of liver damage during liver transplantation, resection surgery, shock, and trauma. It has been reported that TXNIP expression was upregulated in a rat model of hepatic I/R injury. However, the role of TXNIP in the hepatic I/R injury is little known. In our study, we investigated the biological role of TXNIP and its potential molecular mechanism in the human hepatic cell line (HL7702 cells). Using oxygen-glucose deprivation and reoxygenation (OGD/R) to create a cell model of hepatic I/R injury, we found that the mRNA and protein expression levels of TXNIP were upregulated in HL7702 cells exposed to OGD/R. TXNIP overexpression remarkably promoted OGD/R-induced cell apoptosis and lactate dehydrogenase (LDH) release, both of which were significantly decreased by TXNIP knockdown. The production of malondialdehyde (MDA) was also increased by TXNIP overexpression, but was reduced by TXNIP knockdown. Moreover, TXNIP overexpression significantly upregulated the phosphorylation of p38 and JNK, which was remarkably inhibited by TXNIP knockdown. Additionally, p38-specific inhibitor SB203580 abrogated the effect of TXNIP overexpression on OGD/R-induced cell injury. Taken together, these results indicated that TXNIP knockdown alleviated hepatocyte I/R injury through preventing p38/JNK pathway activation. Thus, TXNIP might offer a novel potential therapeutic target for the treatment of hepatic I/R injury.

Shikonin protects H9C2 cardiomyocytes against hypoxia/reoxygenation injury through activation of PI3K/Akt signaling pathway

Myocardial ischemic/reperfusion (I/R) injury often leads to irreversible myocardial cell death and even heart failure, with limited therapeutic possibilities. In the present study, we evaluated the protective effects of shikonin (SHK) against hypoxia/reoxygenation (H/R)-induced cardiomyocyte damage and explored the underlying mechanisms. H9C2 cardiomyocytes were pretreated with different doses of SHK prior to H/R exposure. We observed that SHK pretreatment significantly increased cell viability, attenuated LDH release, and suppressed cardiomyocyte apoptosis induced by H/R exposure. SHK pretreatment also restored the loss of mitochondrial membrane potential (MMP) and cytochrome c release. In addition, SHK significantly enhanced the phosphorylation of Akt and GSK-3β in H/R-treated H9C2 cells. These protective effects of SHK were partially reversed by LY294002, a specific PI3K/Akt inhibitor. Therefore, our findings suggested that SHK might be a promising agent for myocardial I/R injury, and PI3K/Akt signaling plays a crucial role during this process.

No indications for platelet activation in acute clinical myocardial or renal ischemia/reperfusion injury

The pathophysiology of ischemia/reperfusion (I/R) injury is complex and poorly understood. Animal studies imply platelet activation as an initiator of the inflammatory response upon reperfusion. However, it remains unclear whether and how these results translate to clinical I/R. This study evaluates putative platelet activation in the context of two forms of clinical I/R (heart valve surgery with aortic-cross clamping, n = 39 and kidney transplantation, n = 34). The technique of sequential selective arteriovenous (AV) measurements over the reperfused organs was applied to exclude the influence of systemic changes occurring during surgery while simultaneously maximizing sensitivity. Platelet activation and degranulation was evaluated by assessing the expression levels of established markers, i.e. RANTES (Regulated on Activation, Normal T Cell Expressed and Secreted), β-thromboglobulin (β-TG), platelet-derived growth factor (PDGF)-BB and CXCL8 (known as interleukin-8), and by employing an in-vitro assay that specifically tests for platelet excitability. Moreover, a histological analysis was performed by means of CD41 staining. Results show stable RANTES, β-TG, PDGF-BB and CXCL8 AV-concentrations within the first half hour over the reperfused organs, suggesting that myocardial and renal I/R are not associated with platelet activation. Results from the platelet excitability assay were in line with these findings and indicated reduced and stable platelet excitability following renal and myocardial reperfusion, respectively. Histological analysis yield evidence of platelet marginalization in the reperfused organs. In conclusion, results from this study do not support a role for platelet activation in early phases of clinical I/R injury.

A mitochondrial-targeting near-infrared fluorescent probe for bioimaging and evaluating endogenous superoxide anion changes during ischemia/reperfusion injury

The outburst of superoxide anion (O₂^-) in mitochondrial during ischemia/reperfusion (I/R) process will cause a series of oxidative damage including polarity loss of mitochondrial membrane potential, overload of secondary cellular calcium, and cascade apoptosis. To monitor the O₂^- level fluctuations as well as to evaluate the relationship between O₂^- concentration and the degree of cell apoptosis during I/R process, we propose a ratiometric near-infrared mitochondrial targeting fluorescent probe Mito-Cy-Tfs for the detection of level changes of O₂^- in cells and in vivo. The probe Mito-Cy-Tfs is composed of three moieties: near-infrared heptamethine cyanine as fluorescence signal transducer, trifluoromethanesulfonamide as fluorescence modulator, and lipophilic triphenylphosphonium cation as mitochondrial guider. The probe can well locate in mitochondria and respond the concentration changes of endogenous O₂^- selectively and sensitively. The probe has been successfully utilized to image the endogenous O₂^- fluctuations in four kinds of cell I/R models (glucose deprivation/reperfusion, serum deprivation/reperfusion, oxygen deprivation/reperfusion and glucose-serum-oxygen deprivation/reperfusion). The probe also exhibits deep tissue penetration for real-time imaging of O₂^-concentration in liver of I/R mice model. We confirm that the adoption of ischemic preconditioning (IPC) and postconditioning (IPTC) can protect liver from I/R injury. The probe can be employed to accurately indicate and evaluate the mutual relationship between the levels of O₂^- and the degrees of organ damage during I/R, IPC and IPTC processes. The above applications make our new probe a potential candidate for the clinical surgery assessment.

Hypothermic machine perfusion in liver transplantation

PURPOSE OF THE REVIEW

The purpose of the review is to report recent human application of hypothermic machine liver perfusion, and to discuss potential protective mechanisms.

RECENT FINDINGS

Human application of hypothermic machine liver perfusion is still very limited. Currently, three transplant centers apply this novel treatment in donation after cardiac death (DCD) or donation after brain death (DBD) liver grafts. In all cases, endischemic perfusion was performed after initial cold storage for organ transport. Perfusion conditions differ slightly in terms of oxygenation (pO2 15-60 kPa), perfusion route (dual vs. portal), perfusion time (2-4 h), and perfusate.

SUMMARY

The current data support the hypothesis that applying endischemic hypothermic machine liver perfusion protects extended criteria DBD and DCD livers from initial reperfusion injury, with better graft function and less biliary complications. Hypothermic machine perfusion may therefore offer revitalization of liver grafts before implantation by a simple and practical perfusion technique with a high impact on enlarging the donor pool. Multicentric phase III randomized control trials in DBD and DCD liver transplantation have been initiated to further test this strategy, which may establish machine liver perfusion in the clinical setting.

Efficacy and Mechanism of Preoperative Simvastatin Therapy on Myocardial Protection after Extracorporeal Circulation

Background

Cardiopulmonary bypass (CPB) causes systemic inflammatory response and ischemia-reperfusion (IR) injury.

Objective

To investigate the effect and mechanism of simvastatin on myocardial injury in cardiac valve surgery with CPB.

Methods

One hundred thirty patients were randomly assigned to the statin group (n = 65) or control group (n = 65). Simvastatin was administered preoperatively and postoperatively. Duration of intensive care unit stay, duration of assisted ventilation, and left ventricular ejection fraction were recorded. Plasma was analysed for troponin T (cTnT), isoenzyme of creatine kinase (CK-MB), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8). Ultrastructure of the myocardium and autophagosomes were observed. Beclin-1, LC3-II/I, P62, AMPK, and the phosphorylation of AMPK in cardiomyocytes were detected.

Results

Simvastatin significantly reduced the duration of assisted ventilation (P = 0.030) and ejection fraction was significantly higher in the statin group (P = 0.024). Simvastatin significantly reduced the levels of cTnT, CK-MB, TNF-α, IL-6, and IL-8 (P < 0.05), reduced the expression of LC3-II/LC3-I and Beclin 1, and increased the expression of phosphorylation of AMPK. Simvastatin reduced the generation of autophagosomes and the ultrastructural injuries to myocardium.

Conclusion

Perioperative statin therapy reduced myocardial injury by regulating myocardial autophagy and activating the phosphorylation of AMPK. The registration number of this study is ChiCTR-TRC-14005164.

[Effect of endomorphin-1 postconditioning against myocardial ischemia-reperfusion injury in rats and the role of Erk1/2 signaling pathway]

OBJECTIVE

To investigate the effect of postischemic treatment with endomorphin-1 (EM-1) against myocardial ischemia/reperfusion (IR) injury in rats and on extracellular signal regulated kinase 1/2 (Erk1/2)-dependent signaling pathway.

METHODS

Sprague-Dawley rats were randomly divided into 5 groups, namely the sham-operated group, IR group, EM-1 post-treatment group (EM50 group), EM-1 post-treatment group with PD98059 treatment (EM50+PD group), and PD98059 post-treatment group (PD group). The hemodynamic indexes of the rats were recorded. After reperfusion, CK-MB, LDH, CTnI, MDA, IL-6, TNF-α, and SOD activities or contents were measured, the infarct size was determined, and the expression levels of Erk1/2, P-Erk1/2 and cleaved caspase-3 were detected using Western blotting.

RESULTS

Compared with the sham group, the IR group showed significantly decreased heart rate and mean arterial pressure (P<0.05), which were increased obviously by EM-1 post-treatment (P<0.05). EM-1 post-treatment also resulted in significantly decreased LDH, CK-MB, CTnI, MDA, IL-6, and TNF-α activities or contents (P<0.05), increased SOD activity (P<0.05), reduced the infarct size (P<0.05), and increased the expression level of P-Erk protein (P<0.05). Compared with EM50 group, EM50+PD group showed significantly decreased heart rate and mean arterial pressure (P<0.05), increased LDH, CK-MB, CTnI, MDA, IL-6, and TNF-α activities or contents (P<0.05), decreased SOD activity, increased infarct size (P<0.05), and lowered expression of P-Erk protein (P<0.05).

CONCLUSION

Postischemic treatment with EM-1 protects the heart against IR injury by improving the cardiac function, inhibiting inflammation, and inhibiting oxidative stress and myocardial apoptosis, and Erk1/2 signaling pathway may be involved in this process.

[Effect of endomorphin-1 postconditioning against myocardial ischemia-reperfusion injury in rats and the role of Erk1/2 signaling pathway]

OBJECTIVE

To investigate the effect of postischemic treatment with endomorphin-1 (EM-1) against myocardial ischemia/reperfusion (IR) injury in rats and on extracellular signal regulated kinase 1/2 (Erk1/2)-dependent signaling pathway.

METHODS

Sprague-Dawley rats were randomly divided into 5 groups, namely the sham-operated group, IR group, EM-1 post-treatment group (EM50 group), EM-1 post-treatment group with PD98059 treatment (EM50+PD group), and PD98059 post-treatment group (PD group). The hemodynamic indexes of the rats were recorded. After reperfusion, CK-MB, LDH, CTnI, MDA, IL-6, TNF-α, and SOD activities or contents were measured, the infarct size was determined, and the expression levels of Erk1/2, P-Erk1/2 and cleaved caspase-3 were detected using Western blotting.

RESULTS

Compared with the sham group, the IR group showed significantly decreased heart rate and mean arterial pressure (P<0.05), which were increased obviously by EM-1 post-treatment (P<0.05). EM-1 post-treatment also resulted in significantly decreased LDH, CK-MB, CTnI, MDA, IL-6, and TNF-α activities or contents (P<0.05), increased SOD activity (P<0.05), reduced the infarct size (P<0.05), and increased the expression level of P-Erk protein (P<0.05). Compared with EM50 group, EM50+PD group showed significantly decreased heart rate and mean arterial pressure (P<0.05), increased LDH, CK-MB, CTnI, MDA, IL-6, and TNF-α activities or contents (P<0.05), decreased SOD activity, increased infarct size (P<0.05), and lowered expression of P-Erk protein (P<0.05).

CONCLUSION

Postischemic treatment with EM-1 protects the heart against IR injury by improving the cardiac function, inhibiting inflammation, and inhibiting oxidative stress and myocardial apoptosis, and Erk1/2 signaling pathway may be involved in this process.

Peripheral artery disease, redox signaling, oxidative stress - Basic and clinical aspects

Reactive oxygen and nitrogen species (ROS and RNS, e.g. H2O2, nitric oxide) confer redox regulation of essential cellular signaling pathways such as cell differentiation, proliferation, migration and apoptosis. At higher concentrations, ROS and RNS lead to oxidative stress and oxidative damage of biomolecules (e.g. via formation of peroxynitrite, fenton chemistry). Peripheral artery disease (PAD) is characterized by severe ischemic conditions in the periphery leading to intermittent claudication and critical limb ischemia (end stage). It is well known that redox biology and oxidative stress play an important role in this setting. We here discuss the major pathways of oxidative stress and redox signaling underlying the disease progression with special emphasis on the contribution of inflammatory processes. We also highlight therapeutic strategies comprising pharmacological (e.g. statins, angiotensin-converting enzyme inhibitors, phosphodiesterase inhibition) and non-pharmacological (e.g. exercise) interventions. Both of these strategies induce potent indirect antioxidant and anti-inflammatory mechanisms that may contribute to an improvement of PAD associated complications and disease progression by removing excess formation of ROS and RNS (e.g. by ameliorating primary complications such as hyperlipidemia and hypertension) as well as the normalization of the inflammatory phenotype suppressing the progression of atherosclerosis.