Hypoxic postconditioning reduces cardiomyocyte loss by inhibiting ROS generation and intracellular Ca2+ overload

Calcium signaling from sarcoplasmic reticulum and mitochondria contact sites in acute myocardial infarction

Acute myocardial infarction (AMI) is a serious condition that occurs when part of the heart is subjected to ischemia episodes, following partial or complete occlusion of the epicardial coronary arteries. The resulting damage to heart muscle cells have a significant impact on patient's health and quality of life. About that, recent research focused on the role of the sarcoplasmic reticulum (SR) and mitochondria in the physiopathology of AMI. Moreover, SR and mitochondria get in touch each other through multiple membrane contact sites giving rise to the subcellular region called mitochondria-associated membranes (MAMs). MAMs are essential for, but not limited to, bioenergetics and cell fate. Disruption of the architecture of these regions occurs during AMI although it is still unclear the cause-consequence connection and a complete overview of the pathological changes; for sure this concurs to further damage to heart muscle. The calcium ion (Ca2+) plays a pivotal role in the pathophysiology of AMI and its dynamic signaling between the SR and mitochondria holds significant importance. In this review, we tried to summarize and update the knowledge about the roles of these organelles in AMI from a Ca2+ signaling point of view. Accordingly, we also reported some possible cardioprotective targets which are directly or indirectly related at limiting the dysfunctions caused by the deregulation of the Ca2+ signaling.

Is Intrinsic Cardioprotection a Laboratory Phenomenon or a Clinically Relevant Tool to Salvage the Failing Heart?

Cardiovascular diseases, especially ischemic heart disease, as a leading cause of heart failure (HF) and mortality, will not reduce over the coming decades despite the progress in pharmacotherapy, interventional cardiology, and surgery. Although patients surviving acute myocardial infarction live longer, alteration of heart function will later lead to HF. Its rising incidence represents a danger, especially among the elderly, with data showing more unfavorable results among females than among males. Experiments revealed an infarct-sparing effect of ischemic "preconditioning" (IPC) as the most robust form of innate cardioprotection based on the heart's adaptation to moderate stress, increasing its resistance to severe insults. However, translation to clinical practice is limited by technical requirements and limited time. Novel forms of adaptive interventions, such as "remote" IPC, have already been applied in patients, albeit with different effectiveness. Cardiac ischemic tolerance can also be increased by other noninvasive approaches, such as adaptation to hypoxia- or exercise-induced preconditioning. Although their molecular mechanisms are not yet fully understood, some noninvasive modalities appear to be promising novel strategies for fighting HF through targeting its numerous mechanisms. In this review, we will discuss the molecular mechanisms of heart injury and repair, as well as interventions that have potential to be used in the treatment of patients.

Maintenance of cathepsin D-dependent autophagy-lysosomal function protects against cardiac ischemia/reperfusion injury

Cardiac ischemia/reperfusion(I/R) induced-cardiac vascular endothelial injury is an important pathological process that appears in the early stage of cardiac I/R injury. The autophagy-lysosomal pathway is essential for the maintenance of cellular homeostasis. However, in cardiac I/R injury, the role of the autophagy-lysosomal pathway is controversial. The present study aimed to use oxygen-glucose deprivation/oxygen-glucose resupply(OGD/OGR) in human coronary artery endothelial cells(HCAECs) with I/R injury to assess the role of the autophagy-lysosomal pathway in I/R-induced endothelial injury. The results revealed lysosomal dysfunction and impaired autophagic flux in endothelial cells exposed to OGD/OGR. Meanwhile, our data showed that the levels of cathepsin D(CTSD) decreased time-dependently. Knockdown of CTSD caused lysosomal dysfunction and impaired autophagic flux. Conversely, restoration of CTSD levels protected HCAECs against OGD/OGR induced-defects in autophagy-lysosomal function and cellular damage. Our findings indicated that I/R induced-impaired autophagic flux, rather than excessive autophagic initiation, mediates endothelial cells injury. The maintenance of autophagy-lysosomal function is critical to protect endothelial cells against I/R injury, and CTSD is a key regulator. Thus, strategies focused on restoring CTSD function are potentially novel treatments for cardiac reperfusion injury.

Icariin protects cerebral neural cells from ischemia‑reperfusion injury in an in vitro model by lowering ROS production and intracellular calcium concentration

Ischemia is one of the major causes of stroke. The present study investigated the protection of cultured neural cells by icariin (ICA) against ischemia-reperfusion (I/R) injury and possible mechanisms underlying the protection. Neural cells were isolated from neonatal rats and cultured in vitro. The cells were subjected to oxygen-glucose deprivation and reoxygenation (OGD-R) as an I/R mimic to generate I/R injury, and were post-OGD-R treated with ICA. Following the treatments, cell viability, apoptosis, reactive oxygen species (ROS), lactate dehydrogenase (LDH), superoxide dismutase (SOD) and Ca²⁺ concentration were assessed using Cell Counting Kit-8 assay, flow cytometry, CyQUANT™ LDH Cytotoxicity Assay, H₂DCFDA and SOD colorimetric activity kit. After OGD-R, considerable I/R injury was observed in the neural cells, as indicated by reduced cell viability, increased apoptosis and increased production of ROS and LDH (P<0.05). Cellular Ca²⁺ concentration was also increased, while SOD activity remained unchanged. Post-OGD-R ICA treatments increased cell viability up to 87.1% (P<0.05) and reduced apoptosis as low as 6.6% (P<0.05) in a concentration-dependent manner. The treatments also resulted in fewer ROS (P<0.05), lower extracellular LDH content (440.5 vs. 230.3 U/l; P<0.05) and reduced Ca²⁺ increase (P<0.05). These data suggest that ICA protects the neural cells from I/R injury in an in vitro model through antioxidation activity and maintaining cellular Ca²⁺ homeostasis. This function may be explored as a potential therapeutic strategy for ischemia-related diseases after further in vivo studies.

A computational model of cardiomyocyte metabolism predicts unique reperfusion protocols capable of reducing cell damage during ischemia/reperfusion

If a coronary blood vessel is occluded and the neighboring cardiomyocytes deprived of oxygen, subsequent reperfusion of the ischemic tissue can lead to oxidative damage due to excessive generation of reactive oxygen species. Cardiomyocytes and their mitochondria are the main energy producers and consumers of the heart, and their metabolic changes during ischemia seem to be a key driver of reperfusion injury. Here, we hypothesized that tracking changes in cardiomyocyte metabolism, such as oxygen and ATP concentrations, would help in identifying points of metabolic failure during ischemia and reperfusion. To track some of these changes continuously from the onset of ischemia through reperfusion, we developed a system of differential equations representing the chemical reactions involved in the production and consumption of 67 molecular species. This model was validated and used to identify conditions present during periods of critical transition in ischemia and reperfusion that could lead to oxidative damage. These simulations identified a range of oxygen concentrations that lead to reverse mitochondrial electron transport at complex I of the respiratory chain and a spike in mitochondrial membrane potential, which are key suspects in the generation of reactive oxygen species at the onset of reperfusion. Our model predicts that a short initial reperfusion treatment with reduced oxygen content (5% of physiological levels) could reduce the cellular damage from both of these mechanisms. This model should serve as an open-source platform to test ideas for treatment of the ischemia reperfusion process by following the temporal evolution of molecular concentrations in the cardiomyocyte.

Cardioprotective effects of co-administration of thymoquinone and ischemic postconditioning in diabetic rats

OBJECTIVES

Ischemia/reperfusion (I/R) is a leading cause of myocardial infarction (MI) injury, contributing to excess injury to cardiac tissues involved in inflammation, apoptosis, and oxidative stress. The present study was conducted to examine the effects of combined thymoquinone (TQ) with ischemic postconditioning (IPostC) therapy on apoptosis and inflammation due to I/R injury in diabetic rat hearts.

MATERIALS AND METHODS

A single dose injection of streptozotocin (STZ; 60 mg/kg) was administered to thirty-two Wistar male rats to induce diabetes. Hearts were fixed on a Langendorff setting and exposed to a 30 min regional ischemia subsequently to 60 min reperfusion. IPostC was induced at the onset of reperfusion by 3 cycles of 30 sec R/I. ELISA, Western blotting assay, and TUNEL staining were applied to assess the cardioprotective effect of IPostC and TQ against I/R injury in diabetic and non-diabetic rats.

RESULTS

Administration of TQ alone in non-diabetic isolated hearts significantly diminished CK-MB, TNF-α, IL-1β, and apoptosis and enhanced p-GSK-3β and Bcl-2 (P<0.05). Following administration of TQ, the cardioprotective effects of IPostC by elevating p-GSK-3β and Bcl-2 and alleviating apoptosis and inflammation were reestablished compared with non-IPostC diabetic hearts.

CONCLUSION

These results provide substantial evidence that co-administration of TQ plus IPostC can exert cardioprotective effects on diabetic myocardium during I/R damage by attenuating the inflammatory response and apoptosis.

Controlling Reperfusion Injury With Controlled Reperfusion: Historical Perspectives and New Paradigms

Cardiac reperfusion injury is a well-established outcome following treatment of acute myocardial infarction and other types of ischemic heart conditions. Numerous cardioprotection protocols and therapies have been pursued with success in pre-clinical models. Unfortunately, there has been lack of successful large-scale clinical translation, perhaps in part due to the multiple pathways that reperfusion can contribute to cell death. The search continues for new cardioprotection protocols based on what has been learned from past results. One class of cardioprotection protocols that remain under active investigation is that of controlled reperfusion. This class consists of those approaches that modify, in a controlled manner, the content of the reperfusate or the mechanical properties of the reperfusate (e.g., pressure and flow). This review article first provides a basic overview of the primary pathways to cell death that have the potential to be addressed by various forms of controlled reperfusion, including no-reflow phenomenon, ion imbalances (particularly calcium overload), and oxidative stress. Descriptions of various controlled reperfusion approaches are described, along with summaries of both mechanistic and outcome-oriented studies at the pre-clinical and clinical phases. This review will constrain itself to approaches that modify endogenously-occurring blood components. These approaches include ischemic postconditioning, gentle reperfusion, controlled hypoxic reperfusion, controlled hyperoxic reperfusion, controlled acidotic reperfusion, and controlled ionic reperfusion. This review concludes with a discussion of the limitations of past approaches and how they point to potential directions of investigation for the future.

Protective effects of metformin against myocardial ischemia‑reperfusion injury via AMPK‑dependent suppression of NOX4

Numerous studies have demonstrated that metformin can reduce the incidence of myocardial infarction and improve the prognosis of patients. However, its specific mechanism has not been determined. Using a rat model of myocardial ischemia-reperfusion injury (MIRI), it was observed that metformin significantly reduced infarct size, and decreased the levels of plasma lactate dehydrogenase and creatine kinase-MB form. A TTC-Evans blue staining was used to detect the infarct size and MTT assay was used to evaluate the cell viability. TUNEL assay was performed to evaluate apoptosis. Furthermore, 4-hydroxynonenal was detected by immunohistochemical staining. mRNA expression levels were detected by reverse transcription-quantitative PCR; protein expression levels were detected by immunoblotting. When treated with metformin, the number of TUNEL-positive cells was significantly decreased. Reduced 4HNE immunoreactivity was observed in metformin-treated rats as determined via immunohistochemistry. Furthermore, NADPH oxidase 4 (NOX4) was downregulated by metformin at both the mRNA and protein levels, and adenosine 5′-monophosphate-activated protein kinase (AMPK) phosphorylation was increased by metformin. In a primary myocardial hypoxia-reoxygenation cell model, metformin increased the viability of cardiomyocytes and reduced the content of malondialdehyde. It was also found that metformin upregulated the phosphorylation of AMPK and decreased the expression of NOX4. Furthermore, pre-treatment with AMPK inhibitor compound-C could block the effect of metformin, indicated by increased NOX4 compared with metformin treatment alone. These results suggested that metformin was capable of reducing the oxidative stress injury induced by MIRI. In conclusion, the present study indicated that metformin activated AMPK to inhibit the expression of NOX4, leading to a decrease in myocardial oxidative damage and apoptosis, thus alleviating reperfusion injury.

Implications of Oxidative and Nitrosative Post-Translational Modifications in Therapeutic Strategies against Reperfusion Damage

Post-translational modifications based on redox reactions "switch on-off" the biological activity of different downstream targets, modifying a myriad of processes and providing an efficient mechanism for signaling regulation in physiological and pathological conditions. Such modifications depend on the generation of redox components, such as reactive oxygen species and nitric oxide. Therefore, as the oxidative or nitrosative milieu prevailing in the reperfused heart is determinant for protective signaling, in this review we defined the impact of redox-based post-translational modifications resulting from either oxidative/nitrosative signaling or oxidative/nitrosative stress that occurs during reperfusion damage. The role that cardioprotective conditioning strategies have had to establish that such changes occur at different subcellular levels, particularly in mitochondria, is also presented. Another section is devoted to the possible mechanism of signal delivering of modified proteins. Finally, we discuss the possible efficacy of redox-based therapeutic strategies against reperfusion damage.

Effect of Composite Nanoparticle CeO₂ on Myocardial Ischemic Re-Infusion of Cardio Myocyte Apoptosis in Mouse

The myocardial I/R damage is very complicated. Apoptosis is considered to its a critical mechanism. During the cardiac muscle I/R process, oxygen-free radicals play a pivotal role. Arrhythmias, as well as enlargement of the area of myocardial infarction after cardiac muscle I/R process, are caused by adequate blast generated O^2- ion free radicals. During the ischemia-reperfusion process, a large amount of O^2- ion free radicals destroyed the cell structure, and it undergoes lipid peroxidation with unsaturated fatty acids that contain a large number of phospholipids in the cell membrane, causing membrane proteins such as ion channels and enzymes on the cell membrane. The activity of cell is reduced, which affects the function of cell membrane and organelle membrane, destroys its integrity and reduces fluidity.We observed the effects of cerium dioxide nanoparticles on glutathione peroxidase as well as superoxide dismutase, also propionate in myocardial tissue of I/R injury in the mouse. Its effects of malondialdehyde and apoptosis were explored to see its protective effect and to provide more preventive measures for ischemia-reperfusion injury.

Ischemia-Reperfusion Intervention: From Enhancements in Exercise Performance to Accelerated Performance Recovery-A Systematic Review and Meta-Analysis

It has been demonstrated that brief cycles of ischemia followed by reperfusion (IR) applied before exercise can improve performance and, IR intervention, applied immediately after exercise (post-exercise ischemic conditioning—PEIC) exerts a potential ergogenic effect to accelerate recovery. Thus, the purpose of this systematic review with meta-analysis was to identify the effects of PEIC on exercise performance, recovery and the responses of associated physiological parameters, such as creatine kinase, perceived recovery and muscle soreness, over 24 h after its application. From 3281 studies, six involving 106 subjects fulfilled the inclusion criteria. Compared to sham (cuff administration with low pressure) and control interventions (no cuff administration), PEIC led to faster performance recovery (p = 0.004; ES = −0.49) and lower increase in creatine kinase (p < 0.001; effect size (ES) = −0.74) and muscle soreness (p < 0.001; ES = −0.88) over 24 h. The effectiveness of this intervention is more pronounced in subjects with low/moderate fitness level and at least a total time of 10 min of ischemia (e.g., two cycles of 5 min) is necessary to promote positive effects.

Ticagrelor Conditioning Effects Are Not Additive to Cardioprotection Induced by Direct NLRP3 Inflammasome Inhibition: Role of RISK, NLRP3, and Redox Cascades

Inhibition of either P2Y12 receptor or the nucleotide-binding oligomerization domain- (NOD-) like receptor pyrin domain containing 3 (NLRP3) inflammasome provides cardioprotective effects. Here, we investigate whether direct NLRP3 inflammasome inhibition exerts additive effects on myocardial protection induced by the P2Y12 receptor antagonist Ticagrelor. Ticagrelor (150 mg/kg) was orally administered to rats for three consecutive days. Then, isolated hearts underwent an ischemia/reperfusion (30 min ischemia/60 min reperfusion; IR) protocol. The selective NLRP3 inflammasome inhibitor INF (50 μM) was infused before the IR protocol to the hearts from untreated animals or pretreated with Ticagrelor. In parallel experiments, the hearts isolated from untreated animals were perfused with Ticagrelor (3.70 μM) before ischemia and subjected to IR. The hearts of animals pretreated with Ticagrelor showed a significantly reduced infarct size (IS, 49 ± 3% of area at risk, AAR) when compared to control IR group (69 ± 2% of AAR). Similarly, ex vivo administration of INF before the IR injury resulted in significant IS reduction (38 ± 3% of AAR). Myocardial IR induced the NLRP3 inflammasome complex formation, which was attenuated by either INF pretreatment ex vivo, or by repeated oral treatment with Ticagrelor. The beneficial effects induced by either treatment were associated with the protective Reperfusion Injury Salvage Kinase (RISK) pathway activation and redox defence upregulation. In contrast, no protective effects nor NLRP3/RISK modulation were recorded when Ticagrelor was administered before ischemia in isolated heart, indicating that Ticagrelor direct target is not in the myocardium. Our results confirm that Ticagrelor conditioning effects are likely mediated through platelets, but are not additives to the ones achieved by directly inhibiting NLRP3.

Effect of Shenfu Injection on Isolated Empty Beating Hearts from Miniature Pigs

OBJECTIVE

To investigate the effect of Shenfu (SF) injection on donor heart preservation.

METHODS

Twelve pigs were randomly divided into SF group (n=6) and control group (n=6). After eight hours of perfusion, the differences in hemoglobin, the expression of Bcl-2 and BAX, and changes in the myocardial ultrastructure were compared to illustrate the effects of SF injection in heart preservation.

RESULTS

The differences in free hemoglobin between the SF group and the control group were statistically significant (P=0.001), and there was significant interaction of groups with times (P=0.019), but the perfusion time may not be associated with the hemoglobin concentration (P=0.616). According to Western blotting analysis, the expression of Bcl-2 was higher in the SF group than in the control group, while the expression of BAX was not different between the two groups. As to ultrastructural changes, both groups exhibited mitochondrial swelling and myofilament lysis, but the degree of damage in the SF group was smaller.

CONCLUSION

Our study suggests that the application of SF injection for heart preservation may protect against cardiomyocytes and erythrocytes apoptosis, and Bcl-2 protein may play a role in these physiological processes.

Nanotoxicology of Dendrimers in the Mammalian Heart: ex vivo and in vivo Administration of G6 PAMAM Nanoparticles Impairs Recovery of Cardiac Function Following Ischemia-Reperfusion Injury

Aim

The effects of polyamidoamine (PAMAM) dendrimers on the mammalian heart are not completely understood. In this study, we have investigated the effects of a sixth-generation cationic dendrimer (G6 PAMAM) on cardiac function in control and diabetic rat hearts following ischemia-reperfusion (I/R) injury.

Methods

Isolated hearts from healthy non-diabetic (Ctr) male Wistar rats were subjected to ischemia and reperfusion (I/R). LV contractility and hemodynamics data were computed digitally whereas cardiac damage following I/R injury was assessed by measuring cardiac enzymes. For ex vivo acute exposure experiments, G6 PAMAM was administered during the first 10 mins of reperfusion in Ctr animals. In chronic in vivo studies, nondiabetic rats (Ctr) received either vehicle or daily i.p. injections of G6 PAMAM (40 mg/kg) for 4 weeks. Diabetic (D) animals received either vehicle or daily i.p. injections of G6 PAMAM (10, 20 or 40 mg/kg) for 4 weeks. The impact of G6 PAMAM on pacing-postconditioning (PPC) was also studied in Ctr and D rats.

Results

In ex vivo studies, acute administration of G6 PAMAM to isolated Ctr hearts during reperfusion dose-dependently impaired recovery of cardiac hemodynamics and vascular dynamics parameters following I/R injury. Chronic daily i.p. injections of G6 PAMAM significantly (P<0.01) impaired recovery of cardiac function following I/R injury in nondiabetic animals but this was not generally observed in diabetic animals except for CF which was impaired by about 50%. G6 PAMAM treatment completely blocked the protective effects of PPC in the Ctr animals.

Conclusion

Acute ex vivo or chronic in vivo treatment with naked G6 PAMAM dendrimer can significantly compromise recovery of non-diabetic hearts from I/R injury and can further negate the beneficial effects of PPC. Our findings are therefore extremely important in the nanotoxicological evaluation of G6 PAMAM dendrimers for potential clinical applications in physiological and pathological settings.

Mitochondrial ROS in myocardial ischemia reperfusion and remodeling

Despite major progress in interventional and medical treatments, myocardial infarction (MI) and subsequent development of heart failure (HF) are still associated with high mortality. Both during ischemia reperfusion (IR) in the acute setting of MI, as well as in the chronic remodeling process following MI, oxidative stress substantially contributes to cardiac damage. Reactive oxygen species (ROS) generated within mitochondria are particular drivers of mechanisms contributing to IR injury, including induction of mitochondrial permeability transition or oxidative damage of intramitochondrial structures and molecules. But even beyond the acute setting, mechanisms like inflammatory signaling, extracellular remodeling, or pro-apoptotic signaling that contribute to post-infarction remodeling are regulated by mitochondrial ROS. In the current review, we discuss both sources and consequences of mitochondrial ROS during IR and in the chronic setting following MI, thereby emphasizing the potential therapeutic value of attenuating mitochondrial ROS to improve outcome and prognosis for patients suffering MI.

The Disturbed Function of Neutrophils at the Early Stage of Fat Grafting Impairs Long-Term Fat Graft Retention

BACKGROUND

Fat grafting is a popular soft-tissue filler method; however, the mechanism of its survival and regeneration is still not fully understood. Neutrophils are the frontier inflammatory cells and closely associated with tissue regeneration. To understand the role of neutrophils in fat graft retention, we adopted neutrophil depletion and up-regulation models.

METHODS

Mouse inguinal fat (approximately 200 mg) was transferred autologously. The anti-mouse Ly6G antibody and lipopolysaccharides were used in the mouse fat grafting model for neutrophil depletion or activation, respectively. We examined the blood and graft stromal vascular fraction by fluorescence-activated cell sorting in manipulation/control groups. Graft weight, vascularization, and secreted factors were also compared.

RESULTS

There was a significant reduction/increase of neutrophil counts in the circulation and the transferred fat before day 7 with Ly6G antibody/lipopolysaccharides treatment. Early depletion of neutrophils resulted in incompetent angiogenesis and eventually a poor retention rate (27 ± 8 percent) compared with control (51 ± 10 percent; p < 0.05), whereas up-regulated neutrophils increased the inflammation and reactive oxygen species level, leading to tissue damage and poor retention rate (20 ± 9 percent) compared with control (51 ± 10 percent; p < 0.05). Enhanced macrophage infiltration could be found in both neutrophil depletion and up-regulation groups after week 4.

CONCLUSIONS

Undisturbed neutrophil function is the key to initiating downstream responses of macrophage infiltration, stimulating vessel formation, and regulating inflammation level; thus, it exerts a great impact on the long-term retention rate. Disturbed neutrophil function, either enhanced or weakened, can lead to impaired fat graft retention.

Screening and analysis of key active constituents in Guanxinshutong capsule using mass spectrum and integrative network pharmacology

Guanxinshutong capsule (GXSTC) is an effective and safe traditional Chinese medicine used in the treatment of cardiovascular diseases (CVDs) for many years. However, the targets of this herbal formula and the underlying molecular mechanisms of action involved in the treatment of CVDs are still unclear. In the present study, we used a systems pharmacology approach to identify the active ingredients of GXSTC and their corresponding targets in the calcium signaling pathway with respect to the treatment of CVDs. This method integrated chromatographic techniques, prediction of absorption, distribution, metabolism, and excretion, analysis using Kyoto Encyclopedia of Genes and Genomes, network construction, and pharmacological experiments. 12 active compounds and 33 targets were found to have a role in the treatment of CVDs, and four main active ingredients, including protocatechuic acid, cryptotanshinone, eugenol, and borneol were selected to verify the effect of (GXSTC) on calcium signaling system in cardiomyocyte injury induced by hypoxia and reoxygenation. The results from the present study revealed the active components and targets of GXSTC in the treatment of CVDs, providing a new perspective to enhance the understanding of the role of the calcium signaling pathway in the therapeutic effect of GXSTC.

Pharmacological postconditioning with Neuregulin-1 mimics the cardioprotective effects of ischaemic postconditioning via ErbB4-dependent activation of reperfusion injury salvage kinase pathway

Background

The protective effect of Neuregulin-1 (NRG-1) on heart failure is well established. In this study, we assessed whether NRG-1 could protect the heart by mimicking the cardioprotective effects of ischaemic postconditioning (IP).

Methods

We used a myocardial reperfusion injury rat model in vivo to compare the cardioprotective effects of NRG-1(3 μg/kg, iv. at the onset of reperfusion) and IP. In Langendorff isolated heart perfusion experiments, we used the erythroblastic leukaemia viral oncogene homolog 4 (ErbB4) inhibitor AG1478, a phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 and a mitogen-activated protein/extracellular signal regulated kinase (MEK) inhibitor PD98059 to clarify whether the protective effects of NRG-1and IP depend on the NRG-1/ErbB4 signals and the reperfusion injury salvage kinase (RISK) pathway. Infarct size was detected by Evans blue and TTC. Apoptosis was detected by TUNEL assays. The expression of NRG-1/ErbB4 and downstream ERK1/2, AKT, AMPK and p70s6K were detected by western blotting. Hematoxylin/eosin (H&E) staining was used for histological analysis.

Results

We found that NRG-1 and IP had similar effects on reducing myocardial infarct size and apoptosis in vivo. NRG-1 heart protein levels were upregulated in the IP group. Phosphorylation of AKT, ERK1/2 and ErbB4 were also increased in both the IP and NRG-1 groups. Furthermore, in Langendorff analyses, the ErbB4 inhibitor AG1478 suppressed the phosphorylation of ErbB4 and the RISK pathway and aggravated myocardial edema and fiber fracture, thereby inhibited the cardioprotective effects in both the IP and NRG-1 groups. For assessment of downstream signals, the PI3K inhibitor LY294002 and the MEK inhibitor PD98059 suppressed the phosphorylation of AKT and ERK1/2 respectively and abolished the cardioprotective effects induced by IP and NRG-1.

Conclusion

In conclusion, both IP and NRG-1 could reduce infarct size and apoptosis through ErbB4-dependent activation of the RISK pathway in the same model; these results indicated the therapeutic potential of NRG-1 as a pharmacological postconditioning agent against myocardial reperfusion injury.

Honokiol Protects against Anti-β1-Adrenergic Receptor Autoantibody-Induced Myocardial Dysfunction via Activation of Autophagy

Myocardial diseases are prevalent syndromes with high mortality rate. The exploration of effective interference is important. Anti-β1-adrenergic receptor autoantibody (β1-AAB) is highly correlated with myocardial dysfunction. The actions and underlying mechanisms of honokiol (HNK) in β1-AAB-positive patients await to be unraveled. In this study, we established a rat model of β1-AAB positive with myocardial dysfunction. Cardiac function following β1-AR-ECII administration was analyzed using the VisualSonics Vevo 770 High-Resolution In Vivo Imaging System. The levels of autophagy-related proteins were detected by Western blotting. Our data revealed that HNK reversed β1-AAB-induced effects and protected myocardial tissues from dysfunction. After HNK treatment, the cardiac contractile ability increased and the LDH activity decreased. HNK attenuated myocardial degeneration. In addition, HNK promoted the activation of the AMP-dependent protein kinase/Unc-51-like autophagy activating kinase (AMPK/ULK) pathway and activated autophagy. These results suggest that HNK protects against β1-AAB-induced myocardial dysfunction via activation of autophagy and it may be a potentially therapeutic compound for β1-AAB-positive myocardial diseases.

Mitochondria "THE" target of myocardial conditioning

Several interventions, such as ischemic preconditioning, remote pre/perconditioning, or postconditioning, are known to decrease lethal myocardial ischemia-reperfusion injury. While several signal transduction pathways become activated by such maneuvers, they all have a common end point, namely, the mitochondria. These organelles represent an essential target of the cardioprotective strategies, and the preservation of mitochondrial function is central for the reduction of ischemia-reperfusion injury. In the present review, we address the role of mitochondria in the different conditioning strategies; in particular, we focus on alterations of mitochondrial function in terms of energy production, formation of reactive oxygen species, opening of the mitochondrial permeability transition pore, and mitochondrial dynamics induced by ischemia-reperfusion.

Signaling mediators modulated by cardioprotective interventions in healthy and diabetic myocardium with ischaemia-reperfusion injury

Ischaemic heart diseases are one of the major causes of death in the world. In most patients, ischaemic heart disease is coincident with other risk factors such as diabetes. Patients with diabetes are more prone to cardiac ischaemic dysfunctions including ischaemia-reperfusion injury. Ischaemic preconditioning, postconditioning and remote conditionings are reliable interventions to protect the myocardium against ischaemia-reperfusion injuries through activating various signaling pathways and intracellular mediators. Diabetes can disrupt the intracellular signaling cascades involved in these myocardial protections, and studies have revealed that cardioprotective effects of the conditioning interventions are diminished in the diabetic condition. The complex pathophysiology and poor prognosis of ischaemic heart disease among people with diabetes necessitate the investigation of the interaction of diabetes with ischaemia-reperfusion injury and cardioprotective mechanisms. Reducing the outcomes of ischaemia-reperfusion injury using targeted strategies would be particularly helpful in this population. In this study, we review the protective interventional signaling pathways and mediators which are activated by ischaemic conditioning strategies in healthy and diabetic myocardium with ischaemia-reperfusion injury.

Survival kinase-dependent pathways contribute to gender difference in the response to myocardial ischemia-reperfusion and ischemic post-conditioning

The response to ischemia/reperfusion and the effects of ischemic post-conditioning (IPC) are sex-dependent, but the mechanisms have not been clarified. Male (M) and female (F) rat hearts isolated and perfused using the Langendorff technique were subject to 30 min of global ischemia (GI) and 60 min reperfusion (R). In IPC hearts, three cycles of 30-sec GI/30-sec R were applied at the beginning of R. Infarct size and myocardial function were assessed. Superoxide production, antioxidant systems, and expressions of phosphorylated forms of serine/threonine kinase (Akt), glycogen synthase kinase 3β (GSK-3β), protein kinase C ε (PKCε), endothelial nitric oxide synthase (eNOS), and apoptosis were measured. In the basal state, superoxide production and apoptosis were lower, and antioxidant systems and phospho-kinase expressions were higher in F rather than in M hearts. After ischemia-reperfusion, infarct size was less in F hearts, and post-ischemic recovery of myocardial function was higher in F rather than in M hearts. Superoxide production, phospho-kinase activity, phospho-eNOS, and apoptosis increased in both sexes while antioxidants decreased in both sexes. After IPC, infarct size, superoxide production, and apoptosis decreased and phospho-eNOS increased in F and M hearts but phospho-kinase expressions and post-ischemic recovery of myocardial function improved only in M hearts. These results show that Akt/GSK-3β/PKCε/eNOS-dependent pathways-mediated superoxide production and apoptosis appear as important factors involved in the observed gender differences.

Short-interval postconditioning protects the bowel against ischaemia-reperfusion injury in rats

Objective

Acute mesenteric ischaemia leads to intestinal damage. Restoration of blood flow results in further damage to tissue, which is called reperfusion injury. This study aimed to investigate the protective effects of short-interval postconditioning and to determine the optimal interval for reperfusion in an experimental rat model of intestinal ischaemia.

Methods

Forty adult male Wistar rats were grouped as follows: sham (Sh), ischaemia + reperfusion (IR), ischaemia + postconditioning for 5 seconds (PC5), ischaemia + postconditioning for 10 seconds (PC10), and ischaemia + postconditioning for 20 seconds (PC20). For postconditioning, 10 cycles of reperfusion (5, 10, or 20 seconds) interspersed by 10 cycles of 10 seconds of ischaemia were performed. Blood glutathione reductase (GR) and glutathione peroxidase (GPx) levels were measured. Intestinal tissue damage was assessed histopathologically.

Results

GR levels were significantly higher in the PC5 group than in the IR group (37.7 ± 9.0 vs. 18.5 ± 2.0 min/g Hb). GPx levels were significantly higher in the PC10 group than in the IR group (43.2 ± 9.2 vs. 15.9 ± 4.6 U/g Hb). The histopathological score was significantly lower in the PC5 group (1.1 ± 0.1) than in the IR group (2.1 ± 0.2).

Conclusion

Short-interval postconditioning reduces reperfusion injury in the ischaemic bowel and the optimal interval for reperfusion is 5 seconds. The long-term effects of short-interval postconditioning and the optimal reperfusion interval in intestinal ischaemia–reperfusion in rats need to be investigated.

Activation of transient receptor potential vanilloid 4 involves in hypoxia/reoxygenation injury in cardiomyocytes

Transient receptor potential vanilloid 4 (TRPV4) is highly expressed in heart and vessels and can be activated during myocardial ischemia/reperfusion (I/R). Recently, we found that treatment with a selective TRPV4 antagonist HC-067047 significantly reduced infarct size, decreased troponin T levels and improved cardiac function in murine model myocardial I/R. This study was undertaken to investigate the mechanism underlying TRPV4-mediated myocardial I/R injury. To mimic myocardial I/R injury, we established a hypoxia/reoxygenation (H/R) model in H9C2 cells and neonatal rat ventricle myocytes (NRVMs) in vitro. TRPV4 mRNA and protein expression was confirmed in the H9C2 and NRVM, whereas functional TRPV4 activity was assessed from Ca²⁺ influx response to a TRPV4 agonist GSK1016790A. TRPV4 functional expression was significantly enhanced during H/R. Furthermore, H/R increased the intracellular Ca²⁺ concentration ([Ca²⁺]_i) and induced cell injury, which were reversed by HC-067047 but was further aggravated by GSK1016790A. Moreover, HC-067047 treatment significantly alleviated the increase of reactive oxygen species (ROS) generation, the depolarization of mitochondrial membrane potential (Δψm) and the opening of mitochondrial permeability transition pore (mPTP) during H/R. On the contrary, GSK1016790A exacerbated those effects. Meanwhile, increase in [Ca²⁺]_i and ROS induced by activation of TRPV4 was almost abolished when cells were cultured in Ca²⁺-free medium. In addition, ROS scavenger NAC obviously reversed activation of TRPV4-induced changes of Δψm and mPTP opening. Finally, we confirmed the direct roles of TRPV4 on cardiac injury and ROS generation in murine model myocardial I/R in vivo. In conclusion, activation of TRPV4 induces Ca²⁺ influx in cardiomyocytes, with subsequent ROS release, depolarizing of Δψm, opening mPTP, inducing injury and TRPV4 has key roles during I/R via these pathways.

Molecular hydrogen potentiates beneficial anti-infarct effect of hypoxic postconditioning in isolated rat hearts: a novel cardioprotective intervention

Generation of free radicals through incomplete reduction of oxygen during ischemia-reperfusion (I/R) is well described. On the other hand, molecular hydrogen (H₂) reduces oxidative stress due to its ability to react with strong oxidants and easily penetrate cells by diffusion, without disturbing metabolic redox reactions. This study was designed to explore cardioprotective potential of hypoxic postconditioning (HpostC) against I/R (30 min global I - 120 min R) in isolated rat hearts using oxygen-free Krebs-Henseleit buffer (KHB). Furthermore, the possibility to potentiate the effect of HpostC by H₂ using oxygen-free KHB saturated with H₂ (H₂ + HpostC) was tested. HPostC was induced by 4 cycles of 1-minute perfusion with oxygen-free KHB intercepted by 1-minute perfusion with normal KHB, at the onset of reperfusion. H₂ + HPostC was applied in a similar manner using H₂-enriched oxygen-free KHB. Cardioprotective effects were evaluated on the basis of infarct size (IS, in % of area at risk, AR) reduction, post-I/R recovery of heart function, and occurrence of reperfusion arrhythmias. HPostC significantly reduced IS/AR compared with non-conditioned controls. H₂ present in KHB during HPostC further decreased IS/AR compared with the effect of HPostC, attenuated severe arrhythmias, and significantly restored heart function (vs. controls). Cardioprotection by HpostC can be augmented by molecular hydrogen infusion.

Ischemic postconditioning during primary percutaneous coronary intervention

BACKGROUND

Although some studies have shown potential benefit for ischemic postconditioning (IPoC) during primary percutaneous coronary intervention (PCI) in improving surrogate markers of reperfusion and infarction size, the benefit of this approach on clinical outcomes remains unknown.

METHODS AND RESULTS

Electronic databases were searched for randomized clinical trials that compared IPoC versus conventional treatment during primary PCI. Random effects DerSimonian-Laird risk ratios (RR) were calculated for different clinical and surrogate outcomes. The main outcome of this analysis was all-cause mortality. A total of 25 trials involving 3,619 patients were included in the analysis. At a mean follow up of 14 months (95% confidence interval (CI) 8.6-19.4 months), the incidence of all-cause mortality was 4.9% [95% CI 3.8-6.0%] in the IPoC group versus 3.8% [95% CI 1.9-5.7%] in the control group (RR 0.92, 95% CI 0.68-1.24, P = 0.74). The risk of reinfarction (2.7% [95% CI 1.1-4.3%] vs. 2.3% [0.6-4.0%]; RR 1.29, 95% CI 0.62-2.68, P = 0.72), heart failure (3.6% [95% CI 2.0-5.1%] vs. 5.7% [95% CI 3.3-8.2%]; RR 0.77, 95% CI 0.58-1.06, P = 0.24), target vessel revascularization (3.2% [95% CI 1.7-4.7%] vs. 2.4% [95% CI 1.4-3.3%]; RR 1.40, 95% CI 0.90-2.20, P = 0.20), and stent thrombosis (2.4% [95% CI 1.1-3.8%] vs. 1.8% [95% CI 0.5-3.2%]); RR 1.50, 95% CI 0.60-3.70, P = 0.40) was similar in both groups.

CONCLUSIONS

IPoC does not appear to reduce the risk of clinical adverse events in patients with ST-elevation myocardial infarction undergoing primary PCI. © 2017 Wiley Periodicals, Inc.

Four Main Active Ingredients Derived from a Traditional Chinese Medicine Guanxin Shutong Capsule Cause Cardioprotection during Myocardial Ischemia Injury Calcium Overload Suppression

Guanxin Shutong capsule is a traditional Chinese medicine for the treatment of myocardial ischemia (MI). Previous studies have shown that the formula has four main active ingredients (FMAI), protocatechuic acid, cryptotanshinone, borneol, and eugenol. However, the mechanisms of action of these FMAI against MI injury are still not well known. The aim of the present study was to evaluate the protective effects of the FMAI on MI in vitro and in vivo. In vitro, rat neonatal cardiomyocytes were isolated, the cell viability and apoptosis rate were, respectively, measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method and fluorescence activating cell sorter, and the intracellular calcium concentration ([Ca²⁺ ]_i ) and CaM and CaMKII δ mRNA as well as protein levels were determined. Meanwhile, their downstream targets of RyR2 and PLB were also measured by western blot. In vivo, a rat model of coronary artery ligation was used to evaluate the cardioprotective effects. Infarct sizes of heart tissues and levels of serum biochemical indicators, including creatine kinase, lactate dehydrogenase, superoxide dismutase, and glutamate oxaloacetic transaminase, were measured. The in vitro results showed that the FMAI inhibited cell apoptosis, reduced [Ca²⁺ ]_i , decreased the expression of CaM and CaMKII δ, and increased the expression of RyR2 and PLB. In vivo, the FMAI diminished infract size, reduced creatine kinase, lactate dehydrogenase, and aspartate aminotransferase levels, and enhanced superoxide dismutase activity. In conclusion, our data suggest that the FMAI suppressed calcium overload and exerted its protective effect via its antioxidant, antiinflammatory, and anti-apoptosis activities. Copyright © 2017 John Wiley & Sons, Ltd.

Controlled Reperfusion Strategies Improve Cardiac Hemodynamic Recovery after Warm Global Ischemia in an Isolated, Working Rat Heart Model of Donation after Circulatory Death (DCD)

Aims: Donation after circulatory death (DCD) could improve cardiac graft availability, which is currently insufficient to meet transplant demand. However, DCD organs undergo an inevitable period of warm ischemia and most cardioprotective approaches can only be applied at reperfusion (procurement) for ethical reasons. We investigated whether modifying physical conditions at reperfusion, using four different strategies, effectively improves hemodynamic recovery after warm ischemia.

Methods and Results: Isolated hearts of male Wistar rats were perfused in working-mode for 20 min, subjected to 27 min global ischemia (37°C), and 60 min reperfusion (n = 43). Mild hypothermia (30°C, 10 min), mechanical postconditioning (MPC; 2x 30 s reperfusion/30 s ischemia), hypoxia (no O₂, 2 min), or low pH (pH 6.8–7.4, 3 min) was applied at reperfusion and compared with controls (i.e., no strategy). After 60 min reperfusion, recovery of left ventricular work (developed pressure^*heart rate; expressed as percent of pre-ischemic value) was significantly greater for mild hypothermia (62 ± 7%), MPC (65 ± 8%) and hypoxia (61 ± 11%; p < 0.05 for all), but not for low pH (45 ± 13%), vs. controls (44 ± 7%). Increased hemodynamic recovery was associated with greater oxygen consumption (mild hypothermia, MPC) and coronary perfusion (mild hypothermia, MPC, hypoxia), and with reduced markers of necrosis (mild hypothermia, MPC, hypoxia) and mitochondrial damage (mild hypothermia, hypoxia).

Conclusions: Brief modifications in physical conditions at reperfusion, such as hypothermia, mechanical postconditioning, and hypoxia, improve post-ischemic hemodynamic function in our model of DCD. Cardioprotective reperfusion strategies applied at graft procurement could improve DCD graft recovery and limit further injury; however, optimal clinical approaches remain to be characterized.

Role of vitamin D3 combined to alginates in preventing acid and oxidative injury in cultured gastric epithelial cells

Background

Gastric diseases are a worldwide problem in modern society, as reported in the USA, in the range of 0.5–2 episodes/year/person and an incidence of 5–100 episodes/1000/week according to seasons and age. There is convincing evidence that oxidative stress is involved in the pathogenesis of acute gastric injury. Acid secreted from gastric parietal cells determines mucosal injuries which in turn cause inflammation and oxidative stress. Consequent inflammation produces free radicals by mitochondria thus causing lipid peroxidation, oxidative and acidic stress, which can lead to cell apoptosis. Vitamin D_3, the active form of vitamin D, may counteract intracellular cell death and improve epithelial regeneration.

Methods

This study was planned to assess whether vitamin D₃ is a protective factor against acid injury and oxidative stress in gastric epithelial cells. Primary epithelial cells and GTL-16 cells have been used to test the effects of Grisù® alone or in combination with vitamin D₃ during oxidative stress or high acid exposition measuring cell viability, ROS production, cellular adhesion time along with apoptotic, autophagic and survival pathways. The combined effect of Grisù® and vitamin D₃ was found more effective in counteracting the negative consequences of oxidative stress and acidity conditions than some other gastroprotective agents, such as Maalox® or Gaviscon®.

Results

In case of oxidative stress or acidity condition the stimulation with Grisù® alone caused an improvement of cell viability and a reduction of ROS production on epithelial gastric cells. In addition, the adhesion time of the cells was improved. All these effects were increased by the presence of vitamin D₃. Similar data were also observed in primary gastric epithelial cells confirming the results obtained in GTL-16 cells.

Conclusions

These results suggest that Grisù® in combination with vitamin D₃ may exert a gastroprotective effect to maintain or restore the integrity of gastric epithelium through an antioxidant pathway, inhibiting apoptosis and activating survival kinases. Moreover, the combination of Grisù® and vitamin D₃ improves cell viability and decreases ROS production compared to other gastroprotective agents combined with vitamin D₃. All these data were validated using primary cells isolated from gastric tissue.

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-016-0543-z) contains supplementary material, which is available to authorized users.

Research review on the pharmacological effects of astragaloside IV

Astragalus membranaceus Bunge has been used to treat numerous diseases for thousands of years. As the main active substance of Astragalus membranaceus Bunge, astragaloside IV (AS-IV) also demonstrates the potent protective effect on focal cerebral ischemia/reperfusion, cardiovascular disease, pulmonary disease, liver fibrosis, and diabetic nephropathy. Based on studies published during the past several decades, the current state of AS-IV research and the pharmacological effects are detailed, elucidated, and summarized. This review systematically summarizes the pharmacological effects, metabolism mechanism, and the toxicity of AS-IV. AS-IV has multiple pharmacologic effects, including anti-inflammatory, antifibrotic, antioxidative stress, anti-asthma, antidiabetes, immunoregulation, and cardioprotective effect via numerous signaling pathways. According to the existing studies and clinical practices, AS-IV possesses potential for broad application in many diseases.

Polydatin post-treatment alleviates myocardial ischaemia/reperfusion injury by promoting autophagic flux

The present paper provides evidence that polydatin (PD) post-treatment alleviates myocardial ischaemia/reperfusion (I/R) injury by promoting autophagic flux to clear damaged mitochondria to reduce reactive oxygen species (ROS) and cell death.

GsMTx4-D is a cardioprotectant against myocardial infarction during ischemia and reperfusion

GsMTx4 is a selective inhibitor of cationic mechanosensitive ion channels (MSCs) and has helped establish the role of MSCs in cardiac physiology. Inhomogeneous local mechanical stresses due to hypercontracture and swelling during ischemic reperfusion injury (IRI) likely induce elevated MSC activity that can contribute to cation imbalance. The aim of this study was to determine if the D enantiomer of GsMTx4 can act as a cardioprotectant in a mouse IRI model. Ischemia and reperfusion involved ligating a coronary artery followed by release of the ligature. GsMTx4-D was tested by either acute intravenous injection during the ischemic event or by two day pretreatment by intraperitoneal injection, both methods achieving similar results. Based on pharmacokinetic studies, GsMTx4-D dosage was set to achieve expected plasma concentrations between 50 and 5000nM and heart tissue concentrations between 1 and 200nM by intravenous injection. Relative to vehicle injected animals, GsMTx4-D reduced infarct area by ~40% for acute and pretreated animals for both 20 and 45min ischemic challenges. Many indicators of cardiac output were indistinguishable from sham-treated control hearts after GsMTx4-D treatment showing improvement at both 4 and 48h post ischemia, and premature ventricular beats immediately following reperfusion were also significantly reduced. To determine if GsMTx4-D cardioprotection could act directly at the level of cardiomyocytes, we tested its effects in vitro on indicators of IRI damage like cation influx and activation of inflammatory kinases in isolated myocytes cultured under hypoxic conditions. Hypoxia challenged cardiomyocytes treated with 10μM GsMTx4-D showed improved contractility and near normal contraction-related Ca(2+) influx. GsMTx4-D inhibited indicators of ischemic damage such as the apoptotic signaling system JNK/c-Jun, but also inhibited the energy response signaling system Akt kinase. We conclude that GsMTx4-D is a potent cardioprotectant in vivo that may act directly on cardiomyocytes and potentially be useful in multidrug strategies to treat IRI.

Stanniocalcin-1 Protects a Mouse Model from Renal Ischemia-Reperfusion Injury by Affecting ROS-Mediated Multiple Signaling Pathways

Stanniocalcin-1 (STC-1) protects against renal ischemia-reperfusion injury (RIRI). However, the molecular mechanisms remain widely unknown. STC-1 inhibits reactive oxygen species (ROS), whereas most ROS-mediated pathways are associated with ischemic injury. Therefore, to explore the mechanism, the effects of STC-1 on ROS-medicated pathways were studied. Non-traumatic vascular clamps were used to establish RIRI mouse models. The serum levels of STC-1, interleukin-6 (IL-6), interferon (IFN) γ, P53, and capase-3 were measured by ELISA kits. Superoxide dismutase (SOD) and malondialdehyde (MDA) were measured by fluorescence spectrofluorometer. All these molecules changed significantly in a RIRI model mouse when compared with those in a sham control. Kidney cells were isolated from sham and model mice. STC-1 was overexpressed or knockout in these kidney cells. The molecules in ROS-medicated pathways were measured by real-time quantitative PCR and Western blot. The results showed that STC-1 is an effective ROS scavenger. The serum levels of STC-1, MDA and SOD activity were increased while the serum levels of IL-6, iIFN-γ, P53, and capase-3 were decreased in a model group when compared with a sham control (p < 0.05). Furthermore, the levels of STC-1,p53, phosphorylated mitogen-activated protein kinase kinase (p-MEKK-1), c-Jun N-terminal kinase (p-JNK), extracellular signal-regulated kinase (p-ERK), IkB kinase (p-IKK), nuclear factor (NF) κB, apoptosis signal-regulating kinase 1 (ASK-1) and caspase-3 changed significantly in kidney cells isolated from a RIRI model when compared to those isolated from a sham control (p < 0.05). Meanwhile, STC-1 overexpression or silence caused significant changes of the levels of these ROS-mediated molecules. Therefore, STC-1 maybe improve anti-inflammation, anti-oxidant and anti-apoptosis activities by affecting ROS-mediated pathways, especially the phospho-modifications of the respective proteins, resulting in the increase of SOD and reduce of capase-3, p53, IL-6 and IFN-γ.

Protective effect of reduced glutathione C60 derivative against hydrogen peroxide-induced apoptosis in HEK 293T cells

Hydrogen peroxide (H2O2) and free radicals cause oxidative stress, which induces cellular injuries, metabolic dysfunction, and even cell death in various clinical abnormalities. Fullerene (C60) is critical for scavenging oxygen free radicals originated from cell metabolism, and reduced glutathione (GSH) is another important endogenous antioxidant. In this study, a novel water-soluble reduced glutathione fullerene derivative (C60-GSH) was successfully synthesized, and its beneficial roles in protecting against H2O2-induced oxidative stress and apoptosis in cultured HEK 293T cells were investigated. Fourier Transform infrared spectroscopy and (1)H nuclear magnetic resonance were used to confirm the chemical structure of C60-GSH. Our results demonstrated that C60-GSH prevented the reactive oxygen species (ROS)-mediated cell damage. Additionally, C60-GSH pretreatment significantly attenuated H2O2-induced superoxide dismutase (SOD) consumption and malondialdehyde (MDA) elevation. Furthermore, C60-GSH inhibited intracellular calcium mobilization, and subsequent cell apoptosis via bcl-2/bax-caspase-3 signaling pathway induced by H2O2 stimulation in HEK 293T cells. Importantly, these protective effects of C60-GSH were superior to those of GSH. In conclusion, these results suggested that C60-GSH has potential to protect against H2O2-induced cell apoptosis by scavenging free radicals and maintaining intracellular calcium homeostasis without evident toxicity.

Protective effects of vitamin D3 on fimbrial cells exposed to catalytic iron damage

Background

Recently, vitamin D₃ (1alpha, 25-dihydroxyvitamin D) has shown its capability to take part in many extraskeletal functions and its serum levels have been related to patient survival rate and malignancy of many types of neoplasms, including ovarian cancers. Catalytic iron is a free circulating form of iron that is able to generate reactive oxygen species and consequently to promote a number of cellular and tissutal dysfunctions including tumorigenesis. In fertile women an important source of catalytic iron is derived from retrograde menstruation. Epithelial secretory cells from fimbriae of fallopian tubes are greatly exposed to catalytic iron derived from menstrual reflux and so represent the site of origin for most serous ovarian cancers.

The aim of this study was to assess whether vitamin D₃ can play a role in counteracting catalytic iron-induced oxidative stress in cells from fimbriae of fallopian tubes.

Methods

The cells, isolated from women undergoing isteroannessiectomy, were treated with catalytic iron 50-75-100 mM and vitamin D₃ at a concentration ranging from 0.01 to 10 nM to study cell viability, radical oxygen species production, p53, pan-Ras, Ki67 and c-Myc protein expressions through Western Blot, and immunocytochemistry or immunofluorescence analysis.

Results

The pre-treatment with vitamin D₃ 1 nM showed its beneficial effects that consists in a significant decrease in ROS production. In addition a novel finding is represented by the demonstration that pre-treatment with vitamin D₃ is also able to significantly counteract tumoral biomarkers activation, such as p53, pan-Ras, Ki67 and c-Myc, and consequently the catalytic iron-induced cellular injury.

Conclusions

This study demonstrates for the first time that vitamin D₃ plays an important role in preventing catalytic iron-dependent oxidative stress in cultured fimbrial cells. These results support the hypothesis that vitamin D₃ could counteract carcinogenic changes induced by catalytic iron.

Ischemic postconditioning protects the heart against ischemia-reperfusion injury via neuronal nitric oxide synthase in the sarcoplasmic reticulum and mitochondria

As a result of its spatial confinement in cardiomyocytes, neuronal nitric oxide synthase (nNOS) is thought to regulate mitochondrial and sarcoplasmic reticulum (SR) function by maintaining nitroso-redox balance and Ca²⁺ cycling. Thus, we hypothesize that ischemic postconditioning (IPostC) protects hearts against ischemic/reperfusion (I/R) injury through an nNOS-mediated pathway. Isolated mouse hearts were subjected to I/R injury in a Langendorff apparatus, H9C2 cells and primary neonatal rat cardiomyocytes were subjected to hypoxia/reoxygenation (H/R) in vitro. IPostC, compared with I/R, decreased infarct size and improved cardiac function, and the selective nNOS inhibitors abolished these effects. IPostC recovered nNOS activity and arginase expression. IPostC also increased AMP kinase (AMPK) phosphorylation and alleviated oxidative stress, and nNOS and AMPK inhibition abolished these effects. IPostC increased nitrotyrosine production in the cytosol but decreased it in mitochondria. Enhanced phospholamban (PLB) phosphorylation, normalized SR function and decreased Ca²⁺ overload were observed following the recovery of nNOS activity, and nNOS inhibition abolished these effects. Similar effects of IPostC were demonstrated in cardiomyocytes in vitro. IPostC decreased oxidative stress partially by regulating uncoupled nNOS and the nNOS/AMPK/peroxisome proliferator-activated receptor gamma coactivator 1 alpha/superoxide dismutase axis, and improved SR function through increasing SR Ca²⁺ load. These results suggest that IPostC protected hearts against I/R injury via an nNOS-mediated pathway.

Ischemia reperfusion injury as a modifiable therapeutic target for cardioprotection or neuroprotection in patients undergoing cardiopulmonary resuscitation

AIMS

We sought to review cellular changes that occur with reperfusion to try to understand whether ischemia-reperfusion injury (RI) is a potentially modifiable therapeutic target for cardioprotection or neuroprotection in patients undergoing cardiopulmonary resuscitation.

DATA SOURCES

Articles written in English and published in PubMed.

RESULTS

Remote ischemic conditioning (RIC) involves brief episodes of non-lethal ischemia and reperfusion applied to an organ or limb distal to the heart and brain. Induction of hypothermia involves cooling an ischemic organ or body. Both have pluripotent effects that reduce the potential harm associated with RI in the heart and brain by reduced opening of the mitochondrial permeability transition pore. Recent trials of RIC and induced hypothermia did not demonstrate these treatments to be effective. Assessment of the effect of these interventions in humans to date may have been modified by use of concurrent medications including propofol.

CONCLUSIONS

Ongoing research is necessary to assess whether reduction of RI improves patient outcomes.

Role of thioredoxin-1 in ischemic preconditioning, postconditioning and aged ischemic hearts

Thioredoxin is one of the most important cellular antioxidant systems known to date, and is responsible of maintaining the reduced state of the intracellular space. Trx-1 is a small cytosolic protein whose transcription is induced by stress. Therefore it is possible that this antioxidant plays a protective role against the oxidative stress caused by an increase of reactive oxygen species concentration, as occurs during the reperfusion after an ischemic episode. However, in addition to its antioxidant properties, it is able to activate other cytoplasmic and nuclear mediators that confer cardioprotection. It is remarkable that Trx-1 also participates in myocardial protection mechanisms such as ischemic preconditioning and postconditioning, activating proteins related to cellular survival. In this sense, it has been shown that Trx-1 inhibition abolished the preconditioning cardioprotective effect, evidenced through apoptosis and infarct size. Furthermore, ischemic postconditioning preserves Trx-1 content at reperfusion, after ischemia. However, comorbidities such as aging can modify this powerful cellular defense leading to decrease cardioprotection. Even ischemic preconditioning and postconditioning protocols performed in aged animal models failed to decrease infarct size. Therefore, the lack of success of antioxidants therapies to treat ischemic heart disease could be solved, at least in part, avoiding the damage of Trx system.

Gradually Increased Oxygen Administration Improved Oxygenation and Mitigated Oxidative Stress after Resuscitation from Severe Hemorrhagic Shock

BACKGROUND

The optimal oxygen administration strategy during resuscitation from hemorrhagic shock (HS) is still controversial. Improving oxygenation and mitigating oxidative stress simultaneously seem to be contradictory goals. To maximize oxygen delivery while minimizing oxidative damage, the authors proposed the notion of gradually increased oxygen administration (GIOA), which entails making the arterial blood hypoxemic early in resuscitation and subsequently gradually increasing to hyperoxic, and compared its effects with normoxic resuscitation, hyperoxic resuscitation, and hypoxemic resuscitation in severe HS.

METHODS

Rats were subjected to HS, and on resuscitation, the rats were randomly assigned to four groups (n = 8): the normoxic, the hyperoxic, the hypoxemic, and the GIOA groups. Rats were observed for an additional 1 h. Hemodynamics, acid-base status, oxygenation, and oxidative injury were observed and evaluated.

RESULTS

Central venous oxygen saturation promptly recovered only in the hyperoxic and the GIOA groups, and the liver tissue partial pressure of oxygen was highest in the GIOA group after resuscitation. Oxidative stress in GIOA group was significantly reduced compared with the hyperoxic group as indicated by the reduced malondialdehyde content, increased catalase activity, and the lower histologic injury scores in the liver. In addition, the tumor necrosis factor-α and interleukin-6 expressions in the liver were markedly decreased in the GIOA group than in the hyperoxic and normoxic groups as shown by the immunohistochemical staining.

CONCLUSIONS

GIOA improved systemic/tissue oxygenation and mitigated oxidative stress simultaneously after resuscitation from severe HS. GIOA may be a promising strategy to improve resuscitation from HS and deserves further investigation.

Hypoxemic reperfusion of ischemic states: an alternative approach for the attenuation of oxidative stress mediated reperfusion injury

Ischemia and reperfusion (I/R) - induced injury has been described as one of the main factors that contribute to the observed morbidity and mortality in a variety of clinical entities, including myocardial infarction, ischemic stroke, cardiac arrest and trauma. An imbalance between oxygen demand and supply, within the organ beds during ischemia, results in profound tissue hypoxia. The subsequent abrupt oxygen re-entry upon reperfusion, may lead to a burst of oxidative aggression through production of reactive oxygen species by the primed cells. The predominant role of oxidative stress in the pathophysiology of I/R mediated injury, has been well established. A number of strategies that target the attenuation of the oxidative burst have been tested both in the experimental and the clinical setting. Despite these advances, I/R injury continues to be a major problem in everyday medical practice. The aim of this paper is to review the existing literature regarding an alternative approach, termed hypoxemic reperfusion, that has exhibited promising results in the attenuation of I/R injury, both in the experimental and the clinical setting. Further research to clarify its underlying mechanisms and to assess its efficacy in the clinical setting is warranted.

Evaluation of Pulmonary Reperfusion Injury in Rats Undergoing Mesenteric Ischemia and Reperfusion and Protective Effect of Postconditioning on this Process

INTRODUCTION

Some publications have demonstrated the presence of lung reperfusion injury in mesenteric ischemia and reperfusion (I/R), but under to diverse methods. Postconditioning has been recognized as effective in preventing reperfusion injury in various organs and tissues. However, its effectiveness has not been evaluated in the prevention of lung reperfusion injury after mesenteric ischemia and reperfusion.

OBJECTIVE

To evaluate the presence of pulmonary reperfusion injury and the protective effect of ischemic postconditioning on lung parenchyma in rats submitted to mesenteric ischemia and reperfusion.

METHODS

Thirty Wistar rats were distributed into three groups: group A (10 rats), which was held mesenteric ischemia (30 minutes) and reperfusion (60 minutes); group B (10 rats), ischemia and reperfusion, interspersed by postconditioning with two alternating cycles of reperfusion and reocclusion, for two minutes each; and group C (10 rats), ischemia and reperfusion interleaved by postconditioning with four alternating cycles of reperfusion and reocclusion of 30 seconds each. Finally, it was resected the upper lung lobe for histological analysis.

RESULTS

There were mild lung lesions (grade 1) in all samples. There was no statistical difference between groups 1 and 2 (P>0.05).

CONCLUSION

The mesenteric ischemia and reperfusion in rats for thirty and sixty minutes, respectively, caused mild reperfusion injury in lung. Postconditioning was not able to minimize the remote reperfusion injury and there was no difference comparing two cycles of two minutes with four cycles of 30 seconds.

Selective inhibition of PTEN preserves ischaemic post-conditioning cardioprotection in STZ-induced Type 1 diabetic rats: role of the PI3K/Akt and JAK2/STAT3 pathways

Patients with diabetes are vulnerable to MI/R (myocardial ischaemia/reperfusion) injury, but are not responsive to IPostC (ischaemic post-conditioning) which activates PI3K (phosphoinositide 3-kinase)/Akt (also known as PKB or protein kinase B) and JAK2 (Janus kinase 2)/STAT3 (signal transducer and activator of transcription 3) pathways to confer cardioprotection. We hypothesized that increased cardiac PTEN (phosphatase and tensin homologue deleted on chromosome 10), a major negative regulator of PI3K/Akt, is responsible for the loss of diabetic heart sensitivity to IPostC cardioprotecton. In STZ (streptozotocin)-induced Type 1 diabetic rats subjected to MI/R (30 min coronary occlusion and 120 min reperfusion), the post-ischaemic myocardial infarct size, CK-MB (creatine kinase-MB) and 15-F2t-isoprostane release, as well as cardiac PTEN expression were significantly higher than those in non-diabetic controls, concomitant with more severe cardiac dysfunction and lower cardiac Akt, STAT3 and GSK-3β (glycogen synthase kinase 3β) phosphorylation. IPostC significantly attenuated post-ischaemic infarct size, decreased PTEN expression and further increased Akt, STAT3 and GSK-3β phosphorylation in non-diabetic, but not in diabetic rats. Application of the PTEN inhibitor BpV (bisperoxovanadium) (1.0 mg/kg) restored IPostC cardioprotection in diabetic rats. HPostC (hypoxic post-conditioning) in combination with PTEN gene knockdown, but not HPostC alone, significantly reduced H/R (hypoxia/reoxygenation) injury in cardiac H9c2 cells exposed to high glucose as was evident from reduced apoptotic cell death and JC-1 monomer in cells, accompanied by increased phosphorylation of Akt, STAT3 and GSK-3β. PTEN inhibition/gene knockdown mediated restoration of IPostC/HPostC cardioprotection was completely reversed by the PI3K inhibitor wortmannin, and partially reversed by the JAK2 inhibitor AG490. Increased cardiac PTEN, by impairing PI3K/Akt and JAK2/STAT3 pathways, is a major mechanism that rendered diabetic hearts not responsive to post-conditioning cardioprotection.

Abnormalities in Alternative Splicing of Apoptotic Genes and Cardiovascular Diseases

Apoptosis is required for normal heart development in the embryo, but has also been shown to be an important factor in the occurrence of heart disease. Alternative splicing of apoptotic genes is currently emerging as a diagnostic and therapeutic target for heart disease. This review addresses the involvement of abnormalities in alternative splicing of apoptotic genes in cardiac disorders including cardiomyopathy, myocardial ischemia and heart failure. Many pro-apoptotic members of the Bcl-2 family have alternatively spliced isoforms that lack important active domains. These isoforms can play a negative regulatory role by binding to and inhibiting the pro-apoptotic forms. Alternative splicing is observed to be increased in various cardiovascular diseases with the level of alternate transcripts increasing elevated in diseased hearts compared to healthy subjects. In many cases these isoforms appear to be the underlying cause of the disease, while in others they may be induced in response to cardiovascular pathologies. Regardless of this, the detection of alternate splicing events in the heart can serve as useful diagnostic or prognostic tools, while those splicing events that seem to play a causative role in cardiovascular disease make attractive future drug targets.

Very short cycles of postconditioning have no protective effect against reperfusion injury. Experimental study in rats

Introduction

Ischemic postconditioning has been recognized as effective in the prevention of reperfusion injury in situations of ischemia and reperfusion in various organs and tissues. However, it remains unclear what would be the best way to accomplish it, since studies show great variation in the method of their application.

Objective

To assess the protective effect of ischemic postconditioning on ischemia and reperfusion in rats undergoing five alternating cycles of reperfusion and ischemia of 30 seconds each one.

Methods

We studied 25 Wistar rats distributed in three groups: group A (10 rats), which underwent mesenteric ischemia (30 minutes) and reperfusion (60 minutes); Group B (10 rats), undergoing ischemia (30 minutes) and reperfusion (60 minutes), intercalated by postconditioning (5 alternating cycles of reperfusion and ischemia of 30 seconds each one); and group C - SHAM (5 rats), undergoing only laparotomy and manipulation of mesenteric artery. All animals underwent resection of an ileum segment for histological analysis.

Results

The mean lesions degree according to Chiu et al. were: group A, 2.77, group B, 2.67 and group C, 0.12. There was no difference between groups A and B (P>0.05).

Conclusion

Ischemic postconditioning was not able to minimize or prevent the intestinal tissue injury in rats undergoing ischemia and reperfusion process when used five cycles lasting 30 seconds each one.

Decreased autophagy: a major factor for cardiomyocyte death induced by β1-adrenoceptor autoantibodies

Cardiomyocyte death is one major factor in the development of heart dysfunction, thus, understanding its mechanism may help with the prevention and treatment of this disease. Previously, we reported that anti-β₁-adrenergic receptor autoantibodies (β₁-AABs) decreased myocardial autophagy, but the role of these in cardiac function and cardiomyocyte death is unclear. We report that rapamycin, an mTOR inhibitor, restored cardiac function in a passively β₁-AAB-immunized rat model with decreased cardiac function and myocardial autophagic flux. Next, after upregulating or inhibiting autophagy with Beclin-1 overexpression/rapamycin or RNA interference (RNAi)-mediated expression of Beclin-1/3-methyladenine, β₁-AAB-induced autophagy was an initial protective stress response before apoptosis. Then, decreased autophagy contributed to cardiomyocyte death followed by decreases in cardiac function. In conclusion, proper regulation of autophagy may be important for treating patients with β₁-AAB-positive heart dysfunction.