Link between oxidative stress and acute brain ischemia

Breast cancer susceptibility protein 1 (BRCA1) rescues neurons from cerebral ischemia/reperfusion injury through NRF2-mediated antioxidant pathway

Cellular oxidative stress plays a vital role in the pathological process of neural damage in cerebral ischemia/reperfusion (I/R). The breast cancer susceptibility protein 1 (BRCA1), a tumor suppressor, can modulate cellular antioxidant response and DNA repair. Yet the role of BRCA1 in cerebral I/R injury has not been explored. In this study, we observed that BRCA1 was mainly expressed in neurons and was up-regulated in response to I/R insult. Overexpression of BRCA1 attenuated reactive oxygen species production and lipid peroxidation. Enhanced BRCA1 expression promoted DNA double strand break repair through non-homologous end joining pathway. These effects consequently led to neuronal cell survival and neurological recovery. Mechanically, BRCA1 can interact with the nuclear factor (erythroid-derived 2)-like 2 (NRF2) through BRCA1 C-terminal (BRCT) domain. The cross-talk between BRCT and NRF2 activated the NRF2/Antioxidant Response Element signaling pathway and thus protected injured neurons during cerebral I/R. In conclusion, enhanced BRCA1 after cerebral I/R injury may attenuate or prevent neural damage from I/R via NRF2-mediated antioxidant pathway. The finding may provide a potential therapeutic target against ischemic stroke.

•

BRCA1 was up-regulated after cerebral ischemia/reperfusion injury.

•

Up-regulated BRCA1 attenuated cerebral ischemia/reperfusion injury and cognitive impairment.

•

BRCA1 binding to NRF2 via BRCT domain triggered NRF2-mediated antioxidant response.

•

BRCA1 promoted DSBs repair via non-homologous end joining-pathway.

Protective effects of nicorandil against cerebral injury in a swine cardiac arrest model

The present study investigated the effects of nicorandil on cerebral injury following cardiopulmonary resuscitation (CPR) in a swine model of cardiac arrest. CPR was performed on swine following 4 min induced ventricular fibrillation. Surviving animals were randomly divided into 3 groups: A nicorandil group (n=8), a control group (n=8) and a sham group (n=4). The sham group underwent the same surgical procedure to imitate cardiac arrest, but ventricular fibrillation was not induced. When the earliest observable return of spontaneous circulation (ROSC) was detected, the nicorandil and control groups received injections of nicorandil and saline, respectively. Swine serum was collected at baseline and 5 min, 0.5, 3 and 6 h following ROSC. Serum levels of neuron-specific enolase (NSE), S100β, tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) were measured using ELISA. Animals were euthanized and brain tissue samples were collected and assessed using light and electron microscopy 6 h following ROSC. The expression of aquaporin-4 (AQP-4) in the brain tissue was measured using western blotting. Malondialdehyde (MDA) and glutathione (GSH) levels in the brain tissue were determined using thiobarbituric acid and thiobenzoic acid colorimetric methods, respectively. Serum NSE and S100β were significantly higher in the nicorandil and control groups following CPR, compared with baseline (P<0.05). Additionally, NSE and S100β levels were significantly lower in the nicorandil group compared with the control (P<0.05). Pathological examinations and electron microscopy indicated that nicorandil reduced brain tissue damage. TNF-α and IL-6 levels were significantly decreased in the nicorandil group compared with the control group (P<0.05). Furthermore, AQP-4 expression in brain tissue 6 h following ROSC was significantly lower in the nicorandil group compared with the control group (P<0.05). MDA and GSH levels in swine brain tissue decreased and increased, respectively, in the nicorandil group compared with the control group (P<0.05). The results of the present study demonstrate that nicorandil exerts a protective effect against brain injury following cardiac arrest by reducing oxidative damage, inflammatory responses and brain edema post-ROSC.

The chemokine fractalkine (CX3CL1) attenuates H2O2-induced demyelination in cerebellar slices

Background

Fractalkine/CX3CR1 signalling has been implicated in many neurodegenerative and neurological diseases of the central nervous system (CNS). This signalling pathway plays an important role in regulating reactive oxygen species (ROS), as well as itself being altered in conditions of oxidative stress. Here, we investigated the effects of recombinant fractalkine (rCX3CL1) in models of hydrogen peroxide (H₂O₂)-induced demyelination and astrocyte toxicity, within organotypic cerebellar slice cultures.

Methods

Organotypic cerebellar slice cultures were generated from postnatal day 10 C57BL/6J mice to assess myelination. Immunohistochemistry was used to measure the degree of myelination. Fluorescent images were obtained using a leica SP8 confocal microscope and data analysed using ImageJ software.

Results

We show here, for the first time, that rCX3CL1 significantly attenuated bolus H₂O₂-induced demyelination as measured by expression of myelin basic protein (MBP) and attenuated reduced vimentin expression. Using the GOX-CAT system to continuously generate low levels of H₂O₂ and induce demyelination, we observed similar protective effects of rCX3CL1 on MBP and MOG fluorescence, although in this model, the decrease in vimentin expression was not altered.

Conclusions

This data indicates possible protective effects of fractalkine signalling in oxidative stress-induced demyelination in the central nervous system. This opens up the possibility of fractalkine receptor (CX3CR1) modulation as a potential new target for protecting against oxidative stress-induced demyelination in both inflammatory and non-inflammatory nervous system disorders.

Protective effect of nicotinamide adenine dinucleotide (NAD+) against spinal cord ischemia-reperfusion injury via reducing oxidative stress-induced neuronal apoptosis

As previous studies demonstrate that oxidative stress and apoptosis play crucial roles in ischemic pathogenesis and nicotinamide adenine dinucleotide (NAD⁺) treatment attenuates oxidative stress-induced cell death among primary neurons and astrocytes as well as significantly reduce cerebral ischemic injury in rats. We used a spinal cord ischemia injury (SCII) model in rats to verify our hypothesis that NAD⁺ could ameliorate oxidative stress-induced neuronal apoptosis. Adult male rats were subjected to transient spinal cord ischemia for 60min, and different doses of NAD⁺ were administered intraperitoneally immediately after the start of reperfusion. Neurological function was determined by Basso, Beattie, Bresnahan (BBB) scores. The oxidative stress level was assessed by superoxide dismutase (SOD) activity and malondialdehyde (MDA) content. The degree of apoptosis was analyzed by deoxyuridinetriphosphate nick-end labeling (TUNEL) staining and protein levels of cleaved caspase-3 and AIF (apoptosis inducing factor). The results showed that NAD⁺ at 50 or 100mg/kg significantly decreased the oxidative stress level and neuronal apoptosis in the spinal cord of ischemia-reperfusion rats compared with saline, as accompanied with the decreased oxidative stress, NAD⁺ administration significantly restrained the neuronal apoptosis after ischemia injury while improved the neurological and motor function. These findings suggested that NAD⁺ might protect against spinal cord ischemia-reperfusion via reducing oxidative stress-induced neuronal apoptosis.

Anti-inflammation Effects of Oxysophoridine on Cerebral Ischemia-Reperfusion Injury in Mice

Oxysophoridine (OSR) is a bioactive alkaloid extracted from the Sophora alopecuroides Linn. Our aim is to explore the potential anti-inflammation mechanism of OSR in cerebral ischemic injury. Mice were intraperitoneally pretreated with OSR (62.5, 125, and 250 mg/kg) or nimodipine (Nim) (6 mg/kg) for 7 days followed by cerebral ischemia. The inflammatory-related cytokines in cerebral ischemic hemisphere tissue were determined by immunohistochemistry staining, Western blot and enzyme-like immunosorbent assay (ELISA). OSR-treated groups observably suppressed the nuclear factor kappa B (NF-κB), intercellular adhesion molecule-1 (ICAM-1), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). OSR-treated group (250 mg/kg) markedly reduced the inflammatory-related protein prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and interleukin-8 (IL-8). Meanwhile, it dramatically increased the interleukin-10 (IL-10). Our study revealed that OSR protected neurons from ischemia-induced injury in mice by downregulating the proinflammatory cytokines and blocking the NF-κB pathway.

Association between total antioxidant capacity and mortality in ischemic stroke patients

Objective

Data on circulating total antioxidant capacity (TAC) levels in ischemic stroke patients compared with healthy controls are limited and provided conflicting findings. There are not data about the association between circulating TAC levels, peroxidation state and outcome in patients with severe ischemic stroke. The objective of this study was to examine the relationship of TAC with 30-day mortality after severe ischemic stroke.

Methods

This multicenter study included 58 patients with coma (Glasgow Coma Scale < 9) following severe malignant middle cerebral artery infarction (MMCAI). We measured circulating levels of TAC and malondialdehyde (MDA, a biomarker of lipid peroxidation) on day 1 of severe MMCAI diagnosis. The study endpoint was 30-day mortality.

Results

Non-survivors (n = 29) showed higher serum TAC levels (p < 0.001) and higher serum MDA levels (p = 0.004) than survivors (n = 29). Multiple binomial logistic regression analysis showed that serum TAC levels were associated with 30-day mortality, after controlling for Glasgow Coma Scale and age (odds ratio 1.92; 95 % confidence interval 1.201–3.072; p = 0.006). There was a correlation between serum TAC and MDA levels (rho = 0.35; p = 0.008).

Conclusions

This single-center study in severe MMCAI patients found an association between higher serum TAC levels and 30-day mortality and further identified a relationship between serum TAC levels, lipid peroxidation state and mortality after severe ischemic stroke.

Regeneration in the nervous system with erythropoietin

Globally, greater than 30 million individuals are afflicted with disorders of the nervous system accompanied by tens of thousands of new cases annually with limited, if any, treatment options. Erythropoietin (EPO) offers an exciting and novel therapeutic strategy to address both acute and chronic neurodegenerative disorders. EPO governs a number of critical protective and regenerative mechanisms that can impact apoptotic and autophagic programmed cell death pathways through protein kinase B (Akt), sirtuins, mammalian forkhead transcription factors, and wingless signaling. Translation of the cytoprotective pathways of EPO into clinically effective treatments for some neurodegenerative disorders has been promising, but additional work is necessary. In particular, development of new treatments with erythropoiesis-stimulating agents such as EPO brings several important challenges that involve detrimental vascular outcomes and tumorigenesis. Future work that can effectively and safely harness the complexity of the signaling pathways of EPO will be vital for the fruitful treatment of disorders of the nervous system.

Characterization of secretomes from a human blood brain barrier endothelial cells in-vitro model after ischemia by stable isotope labeling with aminoacids in cell culture (SILAC)

The human immortalized brain endothelial cell line hCMEC/D3 is considered a simple in-vitro model of the blood-brain-barrier. Our aim was to characterize changes in the secretome of hCMEC/D3 subjected to oxygen and glucose deprivation (OGD) to identify new proteins altered after ischemia and that might trigger blood-brain-barrier disruption and test their potential as blood biomarkers for ischemic stroke. Using a quantitative proteomic approach based on SILAC, 19 proteins were found differentially secreted between OGD and normoxia/normoglycemia conditions. Among the OGD-secreted proteins, protein folding was the main molecular function identified and for the main canonical pathways there was an enrichment in epithelial adherens junctions and aldosterone signaling. Western blot was used to verify the MS results in a set of 9 differentially secreted proteins and 5 of these were analyzed in serum samples of 38 ischemic stroke patients, 18 stroke-mimicking conditions and 18 healthy controls.

SIGNIFICANCE

"We characterized changes in the secretome of hCMEC/D3 cells after an ischemic insult by SILAC and identified proteins associated with ischemia that might be involved in the disruption of the blood-brain barrier. Besides we analyzed the putative potential of the candidate proteins to become biomarkers for the diagnosis of ischemic stroke.

Molecular mechanisms of diabetic retinopathy: potential therapeutic targets

Diabetic retinopathy (DR) is the leading cause of blindness in working-age adults in United States. Research indicates an association between oxidative stress and the development of diabetes complications. However, clinical trials with general antioxidants have failed to prove effective in diabetic patients. Mounting evidence from experimental studies that continue to elucidate the damaging effects of oxidative stress and inflammation in both vascular and neural retina suggest its critical role in the pathogenesis of DR. This review will outline the current management of DR as well as present potential experimental therapeutic interventions, focusing on molecules that link oxidative stress to inflammation to provide potential therapeutic targets for treatment or prevention of DR. Understanding the biochemical changes and the molecular events under diabetic conditions could provide new effective therapeutic tools to combat the disease.

Neuroprotective mechanism of the novel melatonin derivative Neu-P11 in brain ischemia related models

Stopping the ischemic cascade by targeting its components is a potential strategy for acute ischemic stroke treatment. During ischemia and especially over reperfusion, oxidative stress plays a major role in causing neuronal cell death. Melatonin has been previously reported to provide neuroprotective effects in in vivo models of stroke by a mechanism that implicates melatonin receptors. In this context, this study was planned to test the potential neuroprotective effects of the novel melatonin MT1/MT2 receptor agonist, Neu-P11, against brain ischemia in in vitro and in vivo models, and to elucidate its underlying mechanism of action. Neu-P11 proved to be a good antioxidant, to protect against glutamate-induced excitotoxicity and oxygen and glucose deprivation in hippocampal slices, and to reduce infarct volume in an in vivo stroke model. Regarding its mechanism of action, the protective effect of Neu-P11 was reverted by luzindole (melatonin receptor antagonist), AG490 (JAK2 inhibitor), LY294002 (PI3/AKT inhibitor) and PD98059 (MEK/ERK1/2 inhibitor). In conclusion, Neu-P11 affords neuroprotection against brain ischemia in in vitro and in vivo models by activating a pro-survival signaling pathway that involves melatonin receptors, JAK/STAT, PI3K/Akt and MEK/ERK1/2.

Allopurinol protects against ischemic insults in a mouse model of cortical microinfarction

Microinfarcts are common in patients with cognitive decline and dementia. Allopurinol (ALLO), a xanthine oxidase (XO) enzyme inhibitor, has been found to reduce proinflammatory molecules and oxidative stress in the vasculature. We here examined the effect of pre-treatment with allopurinol on the cortical microinfarction. C57BL/6J mice were subjected to a permanent single penetrating arteriole occlusion induced by two-photon laser irradiation. Infarction volume, the activation of glial cells and nitrosative stress in the ischemic brain was assessed using immunohistochemistry. Pre-treatment with ALLO achieved 42% reduction of infarct volume and significantly reduced microglia infiltration, astrocyte proliferation and nitrosative stress in the ischemic brain. These data indicate that ALLO protects against microinfarcts possibly through inhibition of nitrosative stress and attenuation of microglia infiltration as well as astrocytes reactivation.

The effects of obstructive jaundice on the brain: An experimental study

BACKGROUND/OBJECTIVE

The study aims to evaluate the alterations in the brain due to oxidative stress and lipid peroxidation resulting from obstructive jaundice.

METHODS

Forty-one Wistar albino rats were used in this study. Simple laparotomy was performed in the sham group (n = 5). In the remaining 36 rats, the common bile duct (CBD) was found and ligated. They were divided into six groups. Group I, Group II, and Group III were sacrificed at the 3(rd), 7(th), and 14(th) day of ligation, respectively. In Group Id, Group IId, and Group IIId ligated bile ducts were decompressed at the 3(rd), 7(th), and 14(th) day, respectively. One week after decompression these rats were also sacrificed and samples were taken.

RESULTS

After the CBD ligation, serum levels of bilirubin and malondialdehyde were found to be increased progressively in parallel to the ligation time of the CBD. After decompression these values decreased. In electron microscopy evaluation, the damage was found to be irreversible depending on the length of the obstruction period. In Group II, the damage was mostly reversible after the internal drainage period of 7 days. However in Group III, the tissue damage was found to be irreversible despite the decreased values of oxidative stress and bilirubin.

CONCLUSION

Ultrastructural changes in brain tissue including damage in the glial cells and neurons, were found to be irreversible if the CBD ligation period was >7 days and did not regress even after decompression. It is unreliable to trace these changes using blood levels of bilirubin and free radicals. Therefore, timing is extremely critical for medical therapies and drainage.

Remote ischemic preconditioning for prevention of high-altitude diseases: fact or fiction?

Preconditioning refers to exposure to brief episodes of potentially adverse stimuli and protects against injury during subsequent exposures. This was first described in the heart, where episodes of ischemia/reperfusion render the myocardium resistant to subsequent ischemic injury, which is likely caused by reactive oxygen species (ROS) and proinflammatory processes. Protection of the heart was also found when preconditioning was performed in an organ different from the target, which is called remote ischemic preconditioning (RIPC). The mechanisms causing protection seem to include stimulation of nitric oxide (NO) synthase, increase in antioxidant enzymes, and downregulation of proinflammatory cytokines. These pathways are also thought to play a role in high-altitude diseases: high-altitude pulmonary edema (HAPE) is associated with decreased bioavailability of NO and increased generation of ROS, whereas mechanisms causing acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) seem to involve cytotoxic effects by ROS and inflammation. Based on these apparent similarities between ischemic damage and AMS, HACE, and HAPE, it is reasonable to assume that RIPC might be protective and improve altitude tolerance. In studies addressing high-altitude/hypoxia tolerance, RIPC has been shown to decrease pulmonary arterial systolic pressure in normobaric hypoxia (13% O2) and at high altitude (4,342 m). Our own results indicate that RIPC transiently decreases the severity of AMS at 12% O2. Thus preliminary studies show some benefit, but clearly, further experiments to establish the efficacy and potential mechanism of RIPC are needed.

Dietary supplementation of GrandFusion(®) mitigates cerebral ischemia-induced neuronal damage and attenuates inflammation

OBJECTIVES

Dietary supplementation of fruits and vegetables has been the main stay for nutritional benefit and overall well-being. GrandFusion(®) is a nutritional supplement that contains the natural nutrients from whole fruits and vegetables that include complex nutrients and phytonutrients that contain anti-oxidant, anti-inflammatory, and neuroprotective properties.

METHODS

In this study, C57BL/6 mice were fed a diet supplemented with GrandFusion(®) for 2 months prior to 1 hour of ischemia induced by occlusion of the middle cerebral artery (MCAo) followed by various times of reperfusion. Mice were subjected to MCAo for 1 hour and then at various times following reperfusion, animals were assessed for behavioral outcomes (open field testing, rotarod, and adhesive test removal), and infarct volumes (cresyl violet and triphenyltetrazolium chloride). In addition, to determine the potential mechanisms associated with treatment, the brain tissue was examined for changes in oxidative stress and inflammatory markers.

RESULTS

The GrandFusion(®) diet was able to show a significant protection from infarct damage in the brain and an improvement in neurological outcomes. The diet did not alter heart rate, blood pressure, pO2, pCO2, or pH. In addition, the diet mitigated inflammation by reducing microglial and astrocytic activation following ischemia and reperfusion and limiting oxidative stress.

DISCUSSION

The study demonstrates the neuroprotective effect of a diet rich in fruits and vegetables that contain anti-oxidant and anti-inflammatory against the impact of cerebral ischemia and reperfusion injury.

Poststroke depression as a factor adversely affecting the level of oxidative damage to plasma proteins during a brain stroke

Poststroke depression, the second most serious psychosomatic complication after brain stroke, leads to delay of the rehabilitation process and is associated with an increased disability and cognitive impairment along with increase in term mortality. Research into the biochemical changes in depression is still insufficiently described. The aim of our study was therefore to evaluate the possible association between plasma protein oxidative/nitrative damages and the development of poststroke depression. We evaluated oxidative/nitrative modifications of specific proteins by measurement of 3-nitrotyrosine and carbonyl groups levels using ELISA test. Additionally, we checked differences in proteins thiol groups by spectrophotometric assay based on reaction between DTNB and thiols. We also evaluated catalase activity in erythrocytes measured as ability to decompose H₂O₂. Correlation analysis was performed using Spearman's rank. We observed significant (P < 0.001) differences in all oxidative/nitrative stress parameters in brain stroke patients compared to healthy group. Our research shows that oxidative damage of proteins is correlated with the degree of poststroke depression, while nitrative changes do not show any relationship. We demonstrate a positive correlation between the concentration of carbonyl groups and the Geriatric Depression Scale and a negative correlation between the degree of depression and the concentration of -SH groups or catalase activity.

The Ubiquitin-Proteasome System and Molecular Chaperone Deregulation in Alzheimer's Disease

One of the shared hallmarks of neurodegenerative diseases is the accumulation of misfolded proteins. Therefore, it is suspected that normal proteostasis is crucial for neuronal survival in the brain and that the malfunction of this mechanism may be the underlying cause of neurodegenerative diseases. The accumulation of amyloid plaques (APs) composed of amyloid-beta peptide (Aβ) aggregates and neurofibrillary tangles (NFTs) composed of misfolded Tau proteins are the defining pathological markers of Alzheimer's disease (AD). The accumulation of these proteins indicates a faulty protein quality control in the AD brain. An impaired ubiquitin-proteasome system (UPS) could lead to negative consequences for protein regulation, including loss of function. Another pivotal mechanism for the prevention of misfolded protein accumulation is the utilization of molecular chaperones. Molecular chaperones, such as heat shock proteins (HSPs) and FK506-binding proteins (FKBPs), are highly involved in protein regulation to ensure proper folding and normal function. In this review, we elaborate on the molecular basis of AD pathophysiology using recent data, with a particular focus on the role of the UPS and molecular chaperones as the defensive mechanism against misfolded proteins that have prion-like properties. In addition, we propose a rational therapy approach based on this mechanism.

Hyperbaric oxygen therapy in acute ischemic stroke: a review

Stroke, also known as cerebrovascular disease, is a common and serious neurological disease, which is also the fourth leading cause of death in the United States so far. Hyperbaric medicine, as an emerging interdisciplinary subject, has been applied in the treatment of cerebral vascular diseases since the 1960s. Now it is widely used to treat a variety of clinical disorders, especially hypoxia-induced disorders. However, owing to the complex mechanisms of hyperbaric oxygen (HBO) treatment, the therapeutic time window and the undefined dose as well as some common clinical side effects (such as middle ear barotrauma), the widespread promotion and application of HBO was hindered, slowing down the hyperbaric medicine development. In August 2013, the US Food and Drug Administration declared artery occlusion as one of the 13 specific indications for HBO therapy. This provides opportunities, to some extent, for the further development of hyperbaric medicine. Currently, the mechanisms of HBO therapy for ischemic stroke are still not very clear. This review focuses on the potential mechanisms of HBO therapy in acute ischemic stroke as well as the time window.

Dynamic metabolic changes after permanent cerebral ischemia in rats with/without post-stroke exercise: a positron emission tomography (PET) study

OBJECTIVES

Recent studies have suggested that rehabilitation therapy can accelerate functional recovery after a stroke. Although often overlooked, the cortical hemisphere contralateral to an infarction plays an important role. This study investigates alterations in metabolism of both the damaged ('ipsilateral') as well as the undamaged ('contralateral') hemisphere using (18)F-fluorodeoxyglucose (FDG)-micro-positron emission tomography (PET) in a rat permanent stroke model (with or without post-injury exercise) in order to elucidate the relative importance of either hemisphere to the recovery process following stroke.

METHODS

Thirty-six adult, male Sprague-Dawley rats were divided into four groups before subsequent surgery: sham controls with or without exercise, and ischemic ('stroke') groups with or without exercise. Fluorodeoxyglucose micro-PET imaging was performed at 7, 14, and 21 days after the designated procedure according to group assignment. The imaging data was analyzed by ANOVA using SPMratIHEP software.

RESULTS

Both exercise and ischemia have measurable effects on the motor cortex as well as on the striatum, the effects of which notably include the contralateral hemisphere. To that end, regions of the contralateral motor cortex and striatum have been found to be in a hypermetabolic state following exercise. We further observed that exercise reversed the hypometabolism caused by ischemia back to control levels from day 7 through day 21 on the ipsilateral side. Its effect on the contralateral hemisphere, notably, bolsters an already vigorous response observed after ischemic insult. Thus, the beneficial effect of exercise, as inferred by an increase in metabolic activity, is evident in both hemispheres.

DISCUSSION

These findings suggest that the contralateral hemisphere can compensate for the damaged cortex by remodeling neuronal activity. Thus, clinical treatments specifically targeted to the 'intact' hemisphere following stroke may provide a complimentary strategy for promoting recovery of functional deficits and for improving quality of life in stroke patients.