Inflammatory mechanisms in ischemic stroke: therapeutic approaches

Mannich bases of scutellarein as thrombin-inhibitors: design, synthesis, biological activity and solubility

Two series of 8-aminomethylated derivatives were prepared by Mannich reaction of scutellarein (2) with appropriate aliphatic amines, alicyclic amines and formaldehyde. All the compounds were tested for their thrombin inhibition activity through the analyzation of prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT) and fibrinogen (FIB). The antioxidant activities of these target products were assessed by 1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH) assay using 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay method and the solubility were assessed by ultraviolet (UV). The results showed that morpholinyl aminomethylene substituent derivative (3d) demonstrated stronger anticoagulant activity, better water solubility and good antioxidant activity compared with scutellarein (2), which warrants further development as a agent for ischemic cerebrovascular disease treatment.

Ziprasidone attenuates brain injury after focal cerebral ischemia induced by middle cerebral artery occlusion in rats

Ziprasidone is an atypical antipsychotic drug used for the treatment of schizophrenia. Recent studies have reported that atypical antipsychotics have neuroprotective effects against brain injury. In the present study, the effect of ziprasidone on ischemic brain injury was investigated. Focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) in rats. All the animals experienced ischemia for 1h and then underwent reperfusion. The infarct size induced by MCAO was significantly reduced in the animals that received acute treatment with 5mg/kg ziprasidone and subchronic treatment with 2.5mg/kg ziprasidone for 7 days compared with that in the vehicle-treated animals. The acute treatment with ziprasidone significantly improved neurological functions, as measured by the modified neurological severity score, in a dose-dependent manner. The subchronic treatment produced more rapid recovery from functional deficits than the vehicle treatment. The immunohistochemical investigation revealed that the subchronic treatment prevented severe loss of neuronal marker intensity and attenuated the increased in microglial marker intensity in the infarcted cortical area. These results suggest that ziprasidone has neuroprotective effects in a rat model of ischemic stroke and provide new insight for its clinical applications.

Toll-like receptor 3 agonist Poly I:C protects against simulated cerebral ischemia in vitro and in vivo

AIM

To examine the neuroprotective effects of the Toll-like receptor 3 (TLR3) agonist Poly I:C in acute ischemic models in vitro and in vivo.

METHODS

Primary astrocyte cultures subjected to oxygen-glucose deprivation (OGD) were used as an in vitro simulated ischemic model. Poly I:C was administrated 2 h before OGD. Cell toxicity was measured using MTT assay and LDH leakage assay. The levels of TNFα, IL-6 and interferon-β (IFNβ) in the media were measured using ELISA. Toll/interleukin receptor domain-containing adaptor-inducing IFNβ (TRIF) protein levels were detected using Western blot analysis. A mouse middle cerebral artery occlusion (MCAO) model was u sed for in vivo study. The animals were administered Poly I:C (0.3 mg/kg, im) 2 h before MCAO, and examined with neurological deficit scoring and TTC staining. The levels of TNFα and IL-6 in ischemic brain were measured using ELISA.

RESULTS

Pretreatment with Poly I:C (10 and 20 μg/mL) markedly attenuated OGD-induced astrocyte injury, and significantly raised the cell viability and reduced the LDH leakage. Poly I:C significantly upregulated TRIF expression accompanied by increased downstream IFNβ production. Moreover, Poly I:C significantly suppressed the pro-inflammatory cytokines TNFα and IL-6 production. In mice subjected to MCAO, administration of Poly I:C significantly attenuated the neurological deficits, reduced infarction volume, and suppressed the increased levels of TNFα and IL-6 in the ischemic striatum and cortex.

CONCLUSION

Poly I:C pretreatment exerts neuroprotective and anti-inflammatory effects in the simulated cerebral ischemia models, and the neuroprotection is at least in part due to the activation of the TLR3-TRIF pathway.

Intravenous multipotent adult progenitor cell therapy after traumatic brain injury: modulation of the resident microglia population

Introduction

We have demonstrated previously that the intravenous delivery of multipotent adult progenitor cells (MAPC) after traumatic brain injury affords neuroprotection via interaction with splenocytes, leading to an increase in systemic anti-inflammatory cytokines. We hypothesize that the observed modulation of the systemic inflammatory milieu is related to T regulatory cells and a subsequent increase in the locoregional neuroprotective M2 macrophage population.

Methods

C57B6 mice were injected with intravenous MAPC 2 and 24 hours after controlled cortical impact injury. Animals were euthanized 24, 48, 72, and 120 hours after injury. In vivo, the proportion of CD4⁺/CD25⁺/FOXP3⁺ T-regulatory cells were measured in the splenocyte population and plasma. In addition, the brain CD86⁺ M1 and CD206⁺ M2 macrophage populations were quantified. A series of in vitro co-cultures were completed to investigate the need for direct MAPC:splenocyte contact as well as the effect of MAPC therapy on M1 and M2 macrophage subtype apoptosis and proliferation.

Results

Significant increases in the splenocyte and plasma T regulatory cell populations were observed with MAPC therapy at 24 and 48 hours, respectively. In addition, MAPC therapy was associated with an increase in the brain M2/M1 macrophage ratio at 24, 48 and 120 hours after cortical injury. In vitro cultures of activated microglia with supernatant derived from MAPC:splenocyte co-cultures also demonstrated an increase in the M2/M1 ratio. The observed changes were secondary to an increase in M1 macrophage apoptosis.

Conclusions

The data show that the intravenous delivery of MAPC after cortical injury results in increases in T regulatory cells in splenocytes and plasma with a concordant increase in the locoregional M2/M1 macrophage ratio. Direct contact between the MAPC and splenocytes is required to modulate activated microglia, adding further evidence to the central role of the spleen in MAPC-mediated neuroprotection.

A pentapeptide monocyte locomotion inhibitory factor protects brain ischemia injury by targeting the eEF1A1/endothelial nitric oxide synthase pathway

BACKGROUND AND PURPOSE

Ischemic stroke is a major cause of death worldwide but lacks viable treatment or treatment targets. Monocyte locomotion inhibitory factor (MLIF) is a small heat-stable pentapeptide produced by Entamoeba histolytica in axenic culture, which is supposed to protect the brain from ischemic injury; the mechanism, however, remains unknown. In this study, we further investigated the mechanism underlying the protective role of MLIF in brain ischemia.

METHODS

A middle cerebral artery occlusion model in rats was used for detecting the effect of MLIF in the brain ischemia in vivo. To identify targets of MLIF in brain endothelial cells, we performed immunoprecipitation of biotin-conjugated MLIF and mass spectrometry.

RESULTS

MLIF can protect the brain from ischemic injury in vivo, yielding decreased ischemic volume, prolonged survival, and improved neurological outcome. In vitro studies showed that MLIF displayed protective effects through inhibition of expression of pathological inflammatory adhesion molecules and enhancing endothelial nitric oxide synthase expression and nitric oxide release in the cerebrovascular endothelium. The target screening experiments demonstrated binding of MLIF to the ribosomal protein translation elongation factor eEF1A1. MLIF enhanced endothelial nitric oxide synthase expression through stabilization of endothelial nitric oxide synthase mRNA, and eEF1A1 was shown to be necessary for this enhanced expression. Knockdown of eEF1A1 or inhibition of endothelial nitric oxide synthase attenuated MLIF-mediated inhibition of adhesion molecule expression.

CONCLUSIONS

In this study, we identified a new potential pharmacologically targetable mechanism underlying MLIF's protective effects in brain ischemia through the eEF1A1/endothelial nitric oxide synthase pathway.

Standards and pitfalls of focal ischemia models in spontaneously hypertensive rats: with a systematic review of recent articles

We reviewed the early development of various focal ischemia models in spontaneously hypertensive rats (SHR), and summarized recent reports on this topic. Among 6 focal ischemia models established in divergent substrains of SHR, distal middle cerebral artery occlusion is the most frequently used and relevant method of focal ischemia in the light of penumbra concept. We performed an online PubMed search (2001–2010), and identified 118 original articles with focal ischemia in SHR. Physiological parameters such as age, body weight, and even blood pressure were often neglected in the literature: the information regarding the physiological parameters of SHR is critical, and should be provided within the methodology section of all articles related to stroke models in SHR. Although the quality of recent studies on neuroprotective strategy is improving, the mechanisms underlying the protection should be more clearly recognized so as to facilitate the translation from animal studies to human stroke. To overcome the genetic heterogeneity in substrains of SHR, new approaches, such as a huge repository of genetic markers in rat strains and the congenic strategy, are currently in progress.

Mesenchymal stromal cells in renal ischemia/reperfusion injury

Ischemia/reperfusion (I/R) injury is an inevitable consequence of organ transplantation and a major determinant of patient and graft survival in kidney transplantation. Renal I/R injury can lead to fibrosis and graft failure. Although the exact sequence of events in the pathophysiology of I/R injury remains unknown, the role of inflammation has become increasingly clear. In this perspective, mesenchymal stromal cells (MSCs) are under extensive investigation as potential therapy for I/R injury, since MSCs are able to exert immune regulatory and reparative effects. Various preclinical studies indicate the beneficial effects of MSCs in ameliorating renal injury and accelerating tissue repair. These versatile cells have been shown to migrate to sites of injury and to enhance repair by paracrine mechanisms instead of by differentiating and replacing the injured cells. The first phase I studies of MSCs in human renal I/R injury and kidney transplantation have been started, and results are awaited soon. In this review, preliminary results and opportunities of MSCs in human renal I/R injury are summarized. We might be heading towards a cell-based paradigm shift in the treatment of renal I/R injury.

Microembolism infarcts lead to delayed changes in affective-like behaviors followed by spatial memory impairment

Microvascular disease is defined by microvascular events including arterial wall thickening, microvascular lesions, and microembolic stroke. Characteristics of microvascular disease are observed in the vast majority of patients presenting with late-life depression, and changes in affective behavior may precede microvascular-associated changes in cognitive decline. The current study used a microsphere injection model to test the hypothesis that microembolism infarcts induce depressive-like behaviors in rodents. Further, the study sought to determine whether microembolism-induced changes in affective-like behavior preceded deficits in spatial memory. Microbeads were injected into the internal carotid artery to generate microembolic lesions and behavior was assessed at either a short recovery (SR) time point (4-6 days post-surgery) or long recovery (LR) time point (14-17 days post-surgery). A separate cohort of rats was used to assess spatial memory in the Barnes Maze at the LR time point and beyond (35 days post-surgery). Microembolism infarcts led to an increase in anxiety- and depressive-like behaviors at the LR, but not the SR, time point as evidenced by reduced time in the center of the open field, reduced consumption of a sucrose solution, increased latency to approach a novel female at 14 days and impaired spatial memory at 33 days. A thorough analysis of histological markers and lesion volume revealed that gross histological damage was not predictive of behavioral outcomes, suggesting that alterations in neuronal function may underlie behavioral deficits. Collectively, these data demonstrate that microembolism infarcts are sufficient to induce changes in affective-like behavior and these changes precede alterations in spatial memory.

Class A scavenger receptor promotes cerebral ischemic injury by pivoting microglia/macrophage polarization

Class A scavenger receptor (SR-A) is primarily expressed in microglia/macrophages and plays an important role in immune responses. However, whether SR-A can influence microglia/macrophage polarization in cerebral ischemic injury is not known. To this end we monitored the phenotypic alteration of microglia/macrophages in an animal model of cerebral ischemia injury. SR-A was up-regulated in mouse brains 24h after permanent occlusion of middle cerebral artery (MCAO). SR-A-deficient mice displayed reduced infarct size and improved neurological function compared with wild-type mice littermate controls. Furthermore, a decrease in inflammatory F4/80(+)CD11b(+)CD45(high)CD11c(+) microglia/macrophages and attenuated nuclear factor-kappaB (NF-κB) activation was found in ischemic brains in the SR-A null mice. This was accompanied by alleviation of classically activated M1 macrophage markers and preservation of alternatively activated M2 macrophage markers. These data suggest that SR-A contributes to cerebral ischemic injury by pivoting the phenotype of microglia/macrophages to a skewed M1 polarization.

Acute rosiglitazone treatment during reperfusion after hyperglycemic stroke is neuroprotective not vascular protective

Reperfusion therapy for ischemic stroke can cause secondary brain injury, especially under hyperglycemic (HG) conditions. Here we investigated the effect of acute treatment with rosiglitazone, a peroxisome proliferator-activated receptor-gamma (PPAR-γ) agonist, prior to postischemic reperfusion, on stroke outcome during HG stroke. Male Wistar rats that were either normoglycemic (NG) or HG by STZ (50 mg/kg; for 5-6 days) underwent middle cerebral artery occlusion (MCAO) for 2 hours with 2 hours of reperfusion. Animals were treated i.v. with rosiglitazone (1mg/kg; n=16), rosiglitazone (1mg/kg) + the free radical scavenger Tempol (50mg/kg; n=10) or vehicle (n=16) ten minutes prior to reperfusion and infarct volume, edema formation and cerebral blood flow (CBF) were measured. Compared to NG, HG stroke significantly increased infarct volume from 5.2±3.0% vs. 14.7±3.6% (p<0.05). Rosiglitazone prevented the increased infarct volume induced by HG that was only 6.9±2.0% (p<0.05 vs. HG) but did not have any effect on edema formation that was increased by 3.0% in both HG vehicle and rosiglitazone-treated ipsilateral vs. contralateral hemispheres (p<0.05). Combined treatment of rosiglitazone + Tempol did not significantly change brain water content that remained 2.2% greater than contralateral (p<0.05), but reversed the neuroprotective properties of rosiglitazone in HG MCAO animals such that infarct volume was 14.3±4.4% (p>0.05 vs. vehicle). The lack of an effect of combined treatment of rosiglitazone + Temple may be due to a decrease in reperfusion CBF that was only 60% of baseline (p<0.01) compared to 82% and 89% for HG vehicle and rosiglitazone treated animals (p>0.05). In conclusion, acute rosiglitazone treatment prior reperfusion was neuroprotective but not vascular protective during HG stroke.

Silymarin improves the behavioural, biochemical and histoarchitecture alterations in focal ischemic rats: a comparative evaluation with piracetam and protocatachuic acid

Comparative neuroprotective potential of silymarin, piracetam and protocatechuic acid ethyl ester (PCA) was evaluated in focal ischemic rats. Various pharmacological, biochemical (lipid peroxidation, reduced glutathione, catalase, nitrite content, brain water content) and behavioural (memory impairment, motor control, neurological score) including infarct size and histopathological alterations were evaluated. Silymarin (200mg/kg) and PCA treatment significantly improved behavioural, biochemical and histopathological changes, and reduced water content and infarct size. However, piracetam only improved behavioural and histopathological changes, reduced water content and infarct size. The findings indicate that silymarin exhibits neuroprotective activity better than PCA and piracetam in focal ischemia/reperfusion reflected by its better restoration of behavioural and antioxidant profile.

Endothelin B receptor agonist, IRL-1620, provides long-term neuroprotection in cerebral ischemia in rats

We have earlier shown that stimulation of endothelin B receptors by IRL-1620 provides significant neuroprotection at 24h following cerebral ischemia. However, the effect of IRL-1620 is not known in the subacute phase of cerebral ischemia, where development of cerebral edema further contributes towards brain damage. This study was designed to determine the effect of IRL-1620 on neurological functions, infarct volume, oxidative stress, and endothelin receptors following permanent middle cerebral artery occlusion for 7 days. Rats received three intravenous injections of either vehicle or IRL-1620 [Suc-[Glu9,Ala11,15]-Endothelin-1(8-12)] at 2, 4, and 6h post occlusion. Treatment with IRL-1620 reduced infarct volume (54.06 ± 14.12 mm(3) vs. 177.06 ± 13.21 mm(3)), prevented cerebral edema and significantly improved all neurological and motor function parameters when compared to the vehicle-treated group. Vehicle-treated middle cerebral artery occluded rats demonstrated high levels of malondialdehyde and low levels of reduced glutathione and superoxide dismutase; these effects were reversed in IRL-1620 treated rats. No change in expression of endothelin A receptor was observed 7 days after induction of cerebral ischemia in vehicle or IRL-1620 treated rats. Rats receiving IRL-1620 demonstrated an upregulation of endothelin B receptor only in the infarcted hemisphere 7 days following occlusion. All effects of IRL-1620 were blocked by endothelin B receptor antagonist, BQ788. Results of the present study demonstrate that IRL-1620, administered on day 1, provides significant neuroprotection till 7 days after the induction of cerebral ischemia in rats. Selective endothelin B receptor activation may prove to be a novel therapeutic target in the treatment of cerebral ischemia.

Neuroprotective effect of fucoidin on lipopolysaccharide accelerated cerebral ischemic injury through inhibition of cytokine expression and neutrophil infiltration

In our previous study, we reported that lipopolysaccharide (LPS) activated microglia and accelerated cerebral ischemic injury in the rat brain through the overexpression of cytokines in microglia. In the present study, we investigated the effect of the intraperitoneal administration of fucoidin, a potent inhibitor of leukocyte rolling and anti-inflammatory agent, against accelerated cerebral ischemic injury by LPS pretreatment using rats. We found that fucoidin treatment inhibited the expressions of some brain cytokine or chemokine mRNA such as IL-8, TNF-α and iNOS in the brain of the rats treated only with LPS. We also observed that fucoidin treatment dramatically decreased the infarct size in accelerated cerebral ischemic injury induced by LPS treatment at an early time after ischemic injury. In addition, the immunoreactivity of myleoperoxidase (MPO), a marker for quantifying neutrophil accumulation, was distinctively decreased in the ischemic brain of the fucoidin-treated rat. In brief, our results indicate that fucoidin showed a neuroprotective effect on LPS accelerated cerebral ischemic injury through inhibiting the expression of some cytokine/chemokine and neutrophil recruitments.

Inhibition of P2X7 receptor ameliorates transient global cerebral ischemia/reperfusion injury via modulating inflammatory responses in the rat hippocampus

Background

Neuroinflammation plays an important role in cerebral ischemia/reperfusion (I/R) injury. The P2X7 receptor (P2X7R) has been reported to be involved in the inflammatory response of many central nervous system diseases. However, the role of P2X7Rs in transient global cerebral I/R injury remains unclear. The purpose of this study is to determine the effects of inhibiting the P2X7R in a rat model of transient global cerebral I/R injury, and then to explore the association between the P2X7R and neuroinflammation after transient global cerebral I/R injury.

Methods

Immediately after infusion with the P2X7R antagonists Brilliant blue G (BBG), adenosine 5′-triphosphate-2′,3′-dialdehyde (OxATP) or A-438079, 20 minutes of transient global cerebral I/R was induced using the four-vessel occlusion (4-VO) method in rats. Survival rate was calculated, neuronal death in the hippocampal CA1 region was observed using H & E staining, and DNA cleavage was observed by deoxynucleotidyl transferase-mediated UTP nick end labeling TUNEL). In addition, behavioral deficits were measured using the Morris water maze, and RT-PCR and immunohistochemical staining were performed to measure the expression of IL-1β, TNF-α and IL-6, and to identify activated microglia and astrocytes.

Results

The P2X7R antagonists protected against transient global cerebral I/R injury in a dosage-dependent manner. A high dosage of BBG (10 μg) and A-0438079 (3 μg), and a low dosage of OxATP (1 μg) significantly increased survival rates, reduced I/R-induced learning memory deficit, and reduced I/R-induced neuronal death, DNA cleavage, and glial activation and inflammatory cytokine overexpression in the hippocampus.

Conclusions

Our study indicates that inhibiting P2X7Rs protects against transient global cerebral I/R injury by reducing the I/R-induced inflammatory response, which suggests inhibition of P2X7Rs may be a promising therapeutic strategy for clinical treatment of transient global cerebral I/R injury.

Neuroprotective effects of diallyl sulfide against transient focal cerebral ischemia via anti-apoptosis in rats

OBJECTIVES

Diallyl sulfide (DAS) is the main organosulfur component of garlic and it is known for multiple pharmacological actions. Recent studies have demonstrated that DAS has neuroprotective effects against ischemia/reperfusion injury. While some of the possible mechanisms behind this protection have been explored, its ability to inhibit apoptosis has yet to be fully explained. In the present study, the effects of DAS on focal cerebral ischemia in rats were tested and its anti-apoptotic action was explored.

METHODS

To examine the protective effects of DAS, focal cerebral ischemia/reperfusion was induced in rats by transient middle cerebral artery occlusion for 2 hours followed by reperfusion for 24 hours. The animals received DAS in quantities of 100, 150, and 200 mg/kg (intraperitoneal; every day), for 7 days before transient middle cerebral artery occlusion. The neurological score and infarct volume were measured at 24 hours after the end of reperfusion. Apoptotic cells were counted by terminal dUTP nick end labeling staining and apoptotic mechanisms were studied by fluorescence immunohistochemistry staining and western blot analysis.

RESULTS

For animals with induced ischemia/reperfusion, those pretreated with 200 mg/kg DAS showed an infarct volume (22.36 ± 0.67%) significantly lower than that of the non-treated ischemia/reperfusion group (38.23 ± 0.72%), and the percentage of terminal dUTP nick-end labeling-positive cells (23.46 ± 1.02%) of the DAS-pretreated group was also significantly decreased compared to non-treated (36.41 ± 1.58%). Fluorescence immunohistochemistry staining and western blot analysis indicated that DAS reduced caspase-3 expression and increased Bcl-2 expression.

CONCLUSION

These results suggest that the mechanism by which DAS protects the brain from ischemia/reperfusion injury is related to its anti-apoptotic effects in part.

UPEI-100, a conjugate of lipoic acid and apocynin, mediates neuroprotection in a rat model of ischemia/reperfusion

Previous work in our laboratory has provided evidence that preadministration of apocynin and lipoic acid at subthreshold levels for neuroprotection enhanced the neuroprotective capacity when injected in combination. Therefore, the present investigation was designed to determine whether a co-drug consisting of lipoic acid and apocynin functional groups bound by a covalent bond, named UPEI-100, is capable of similar efficacy using a rodent model of stroke. Male rats were anesthetized with Inactin (100 mg/kg iv), and the middle cerebral artery was occluded for 6 h or allowed to reperfuse for 5.5 h following a 30-min occlusion (ischemia/reperfusion, I/R). Preadministration of UPEI-100 dose-dependently decreased infarct volume in the I/R model ( P < 0.05), but not in the middle cerebral artery occlusion model of stroke. Using the optimal dose, we then injected UPEI-100 during the stroke or at several time points during reperfusion, and significant neuroprotection was observed when UPEI-100 was administered up to 90 min following the start of reperfusion ( P < 0.05). A time course for this neuroprotective effect showed that UPEI-100 resulted in a decrease in infarct volume following 2 h of reperfusion compared with vehicle. The time course of this neuroprotective effect was also used to study several mediators along the antioxidant pathway and showed that UPEI-100 increased the level of mitochondrial superoxide dismutase and oxidized glutathione and decreased a marker of lipid peroxidation due to oxidative stress (HNE-His adduct formation). Taken together, the data suggest that UPEI-100 may utilize similar pathways to those observed for the two parent compounds; however, it may also act through a different mechanism of action.

Myelin specific cells infiltrate MCAO lesions and exacerbate stroke severity

Although inflammatory responses increase stroke severity, the role of immune cells specific for central nervous system (CNS) antigens remains controversial. Disruption of the blood-brain barrier (BBB) during stroke allows CNS antigens to leak into the peripheral circulation and enhances access of circulating leukocytes to the brain, including those specific for CNS antigens such as myelin oligodendrocyte glycoprotein (MOG) that can induce experimental autoimmune encephalomyelitis (EAE). We here demonstrate for the first time that myelin reactive splenocytes specific for MOG transferred into severe combined immunodeficient (SCID) mice can migrate into the infarct hemisphere of recipients subjected to 60 min middle cerebral artery occlusion (MCAO) and 96 h reperfusion; moreover these cells exacerbate infarct volume and worsen neurological deficits compared to animals transferred with naïve splenocytes. These findings indicate that autoimmunity in the CNS can exert detrimental injury on brain cells and worsen the damage from ischemic stroke.

The transcriptome of cerebral ischemia

The molecular causality and response to stroke is complex. Yet, much of the literature examining the molecular response to stroke has focused on targeted pathways that have been well-characterized. Consequently, our understanding of stroke pathophysiology has made little progress by way of clinical therapeutics since tissue plasminogen activator was approved for treatment nearly a decade ago. The lack of clinical translation is in part due to neuron-focused studies, preclinical models of cerebral ischemia and the paradoxical nature of neuro-inflammation. With the evolution of the Stroke Therapy Academic Industry Roundtable criteria streamlining research efforts and broad availability of genomic technologies, the ability to decipher the molecular fingerprint of ischemic stroke is on the horizon. This review highlights preclinical microarray findings of the ischemic brain, discusses the transcriptome of cerebral preconditioning and emphasizes the importance of further characterizing the role of the neurovascular unit and peripheral white blood cells in mediating stroke damage and repair within the penumbra.

Application of mild therapeutic hypothermia on stroke: a systematic review and meta-analysis

Background. Stroke occurs due to an interruption in cerebral blood supply affecting neuronal function. Body temperature on hospital admission is an important predictor of clinical outcome. Therapeutic hypothermia is promising in clinical settings for stroke neuroprotection. Methods. MEDLINE/PubMed, CENTRAL, Stroke Center, and ClinicalTrials.gov were systematically searched for hypothermia intervention induced by external or endovascular cooling for acute stroke. NIH Stroke Scale (NIHSS) and modified Rankin Scale (mRS) were the main stroke scales used, and mortality was also reported. A meta-analysis was carried out on stroke severity and mortality. Results. Seven parallel-controlled clinical trials were included in the meta-analysis. Sample sizes ranged from 18 to 62 patients, yielding a total of 288. Target temperature (∼33°C) was reached within 3-4 hours. Stroke severity (Cohen's d = −0.17, 95% CI: −0.42 to 0.08, P = 0.32; I² = 73%; Chi² = 21.89, P = 0.0001) and mortality (RR = 1.60, 95% CI: 0.93 to 2.78, P = 0.11; I² = 0%; Chi² = 2.88, P = 0.72) were not significantly affected by hypothermia. Discussion. Hypothermia does not significantly improve stroke severity; however, this finding should be taken with caution due to the high heterogeneity and limited number of included studies. No impact on mortality was observed.

Increased endothelin-1 vasoconstriction in mesenteric resistance arteries after superior mesenteric ischaemia-reperfusion

BACKGROUND AND PURPOSE

Endothelin-1 (ET-1) plays an important role in the maintenance of vascular tone. We aimed to evaluate the influence of superior mesenteric artery (SMA) ischaemia-reperfusion (I/R) on mesenteric resistance artery vasomotor function and the mechanism involved in the changes in vascular responses to ET-1.

EXPERIMENTAL APPROACH

SMA from male Sprague-Dawley rats was occluded (90 min) and following reperfusion (24h), mesenteric resistance arteries were dissected. Vascular reactivity was studied using wire myography. Protein and mRNA expression, superoxide anion (O(2) (•-) ) production and ET-1 plasma concentration were evaluated by immunofluorescence, real-time quantitative PCR, ethidium fluorescence and elisa, respectively.

KEY RESULTS

I/R increased ET-1 plasma concentration, ET-1-mediated vasoconstriction and ET(B) mRNA expression, and down-regulated ET(A) mRNA expression. Immunofluorescence confirmed mRNA results and revealed an increase in ET(B) receptors in the mesenteric resistance artery media layer after I/R. Therefore, the ET(B) receptor agonist sarafotoxin-6 induced a contraction that was inhibited by the ET(B) receptor antagonist BQ788 only in vessels, with and without endothelium, from I/R rats. Furthermore, BQ788 potentiated ET-1 vasoconstriction only in sham rats. Endothelium removal in rings from I/R rats unmasked the inhibition of ET-1 vasoconstriction by BQ788. Endothelium removal, N(ω) -nitro-L-arginine methyl ester and superoxide dismutase abolished the differences in ET-1 vasoconstriction between sham and I/R rats. We also found that I/R down-regulates endothelial NOS mRNA expression and concomitantly enhanced O(2) (•-) production by increasing NADPH oxidase 1 (NOX-1) and p(47phox) mRNA.

CONCLUSIONS AND IMPLICATIONS

Mesenteric I/R potentiated the ET-1-mediated vasoconstriction by a mechanism that involves up-regulation of muscular ET(B) receptors and decrease in NO bioavailability.

A novel experimental in vivo model of cerebral immunomodulation induced by inactivated Staphylococcus epidermidis

The genesis and appropriate treatment of neuroinflammation in various infectious and non-infectious disorders of the central nervous system is still a matter of debate. We introduce an alternative and simple experimental model for the investigation of the cellular inflammatory response to bacterial antigens by stereotactic intracerebral injection of heat-inactivated Staphylococcus epidermidis (HISE). HISE-injection resulted in well-circumscribed intraparenchymal deposits encompassed by an early micro- and astroglial response and a selective but sustained opening of the blood-brain barrier (BBB). After 24h, the HISE collections were densely infiltrated by granulocytes and few circumjacent macrophages that became the predominating immunocompetent cell type from day 4 on. CD8a+ lymphocytes peaked at day 4, whereas CD4+ and CD20+ lymphocytes increased gradually in number, developing a scattered infiltrate until day 17, indicating the initiation of an adaptive immune response. MHC class II presenting cells were abundantly recruited from day 1 and eventually shaped an increasingly dense accumulation within the lesion. Intracerebral HISE administration provides a controlled, highly reproducible and well defined influx of immunocompetent cells across the BBB leading to a distinct and condensed inflammatory reaction. The technique is straightforward, easily feasible and may significantly enable further investigations of the initiation, maintenance and therapeutic modulation of acute neuroinflammation.

Anti-inflammatory properties and pharmacological induction of Hsp70 after brain injury

The 70-kDa heat shock protein (Hsp70) is thought to protect the brain from a variety of insults. Although the mechanism has been largely limited to its chaperone functions, recent work indicates that Hsp70 also modulates inflammatory pathways. Brain injury and ischemia are associated with an immune response that is largely innate. Hsp70 appears to suppress this response and lead to improved neurological outcome. However, most of this work has relied on the use of genetic mutant models or Hsp70 overexpression using gene transfer or heat stress, thus limiting its translational utility. A few compounds have been studied by various disciplines which, through their ability to inhibit Hsp90, can cause induction of Hsp70. The investigation of Hsp70-inducing pharmacological compounds has obvious clinical implications in terms of potential therapies to mitigate neuroinflammation and lead to neuroprotection from stroke or traumatic brain injury. This review will focus on the inflammation modulating properties of Hsp70, and the current literature surrounding the pharmacological induction in acute neurological injury models with comments on potential applications at the clinical level.

Predictive role of high sensitive C-reactive protein in early onset mortality after ischemic stroke

BACKGROUND

High sensitive C-reactive protein (hs-CRP) is a systemic inflammatory marker that is produced in a large amount by hepatocytes in response to interleukin-1 (IL-1), IL-6 and tumor necrosis factor after ischemic stroke.

METHODS

Measurement of hs-CRP in the first 24 hours of onset in 162 patients suffering from ischemic stroke was done. Relation of CRP with the risk of early mortality, National Institutes of Health Stroke Scale (NIHSS), stroke subtypes and other factors was determined.

RESULTS

Regarding to ROC curve analysis, appropriate cut-off point for predicting patients' short time mortality was equal to 2.15 mg/dl in this study. Significantly increased rate of mortality by 13.3 times was seen in patients with simultaneous CRP > 2.15 mg/dl and NIHSS > 10.

CONCLUSION

The Result of this study showed that there is a direct association between hs-CRP and mortality within the first week after stroke. Measuring hs-CRP within the first hours after stroke increases the predicting rate of early mortality risk with cut-off point of 2.15.

Intracerebroventricularly delivered VEGF promotes contralesional corticorubral plasticity after focal cerebral ischemia via mechanisms involving anti-inflammatory actions

Vascular endothelial growth factor (VEGF) has potent angiogenic and neuroprotective effects in the ischemic brain. Its effect on axonal plasticity and neurological recovery in the post-acute stroke phase was unknown. Using behavioral tests combined with anterograde tract tracing studies and with immunohistochemical and molecular biological experiments, we examined effects of a delayed i.c.v. delivery of recombinant human VEGF(165), starting 3 days after stroke, on functional neurological recovery, corticorubral plasticity and inflammatory brain responses in mice submitted to 30 min of middle cerebral artery occlusion. We herein show that the slowly progressive functional improvements of motor grip strength and coordination, which are induced by VEGF, are accompanied by enhanced sprouting of contralesional corticorubral fibres that branched off the pyramidal tract in order to cross the midline and innervate the ipsilesional parvocellular red nucleus. Infiltrates of CD45+ leukocytes were noticed in the ischemic striatum of vehicle-treated mice that closely corresponded to areas exhibiting Iba-1+ activated microglia. VEGF attenuated the CD45+ leukocyte infiltrates at 14 but not 30 days post ischemia and diminished the microglial activation. Notably, the VEGF-induced anti-inflammatory effect of VEGF was associated with a downregulation of a broad set of inflammatory cytokines and chemokines in both brain hemispheres. These data suggest a link between VEGF's immunosuppressive and plasticity-promoting actions that may be important for successful brain remodeling. Accordingly, growth factors with anti-inflammatory action may be promising therapeutics in the post-acute stroke phase.

CDP-choline as a biological supplement during neurorecovery: a focused review

Cytidine 5'-diphosphocholine (CDP-choline or citicoline) is a highly bioavailable compound with potential benefits for aiding neural repair and increasing acetylcholine levels in the central and peripheral nervous system. As a result, many researchers have investigated the use of CDP-choline for various types of neurological insult or conditions, including stroke, traumatic brain injury, and Alzheimer disease. Despite the fact that the safety of the compound has been verified across multiple international studies, evidence for efficacy remains less clear. This may be attributable, at least in part, to several issues, including a lack of randomized clinical trials, a lack of availability of the compound in the United States, and statistical power issues in reported trials. In addition, the fact that CDP-choline has multiple potential points of therapeutic impact makes it an exciting treatment option in theory but also complicates the analysis of efficacy in the sense that multiple mechanisms and time points must be evaluated. Although some clinical conditions do not appear to benefit from CDP-choline treatment, the majority of findings to date have suggested at least minor benefits of treatment. In this review we will examine the evidence in the published literature pertaining to use of CDP-choline in rehabilitation populations and briefly consider the work yet to be done.

Neuroprotective effects of a traditional herbal prescription on transient cerebral global ischemia in gerbils

AIM OF THE STUDY

Kyung-Ok-Ko (KOK), a traditional herbal prescription composed of Rehmannia glutinosa var. purpurae, Panax ginseng, Poria cocos, Lycium chinense, Aquillaria agallocha and honey, has been used to treat age-related symptoms, such as amnesia or dementia, and has been shown to ameliorate scopolamine-induced memory impairment in mice. However, the effects of KOK on transient cerebral global ischemia-induced brain damage are unclear.

MATERIALS AND METHODS

Transient cerebral global ischemia was induced by occluding the bilateral common carotid artery for 5 min followed by reperfusion for 7 days. KOK (0.25, 0.5, 1, or 2 g/kg) was administered orally immediately after reperfusion and once a day over the next 7 days. Y-maze or novel object recognition tasks were to analyze learning and memory capabilities at 4 or 5 days after reperfusion, respectively. Histochemistry and immunohistochemistry were used for evaluation of the effect of KOK on neuronal degeneration.

RESULTS

Histochemical studies showed that KOK increased the number of viable cells detected by Nissl staining and decreased the number of degenerated neuronal cells detected by Fluoro-Jade B staining in the hippocampal CA1 region. In the immunohistochemical study, the sub-chronic KOK administration attenuated the ischemia-induced activation of microglia and astrocytes and the increase of cytokine IL-1β (P<0.05). In addition, KOK administration significantly attenuated the ischemia-induced cognitive impairments observed in the Y-maze and novel object recognition tasks (P<0.05).

CONCLUSION

These findings suggest that the neuroprotective effects of KOK may be mediated by its anti-inflammatory activities, resulting in the attenuation of memory impairment.

Synthesis and bio-activity evaluation of scutellarein as a potent agent for the therapy of ischemic cerebrovascular disease

Scutellarein, the main metabolite of scutellarin in vivo, has relatively better solubility, bioavailability and bio-activity than scutellarin. However, it is very difficult to obtain scutellarein in nature compared with scutellarin. Therefore, the present study focused on establishing an efficient route for the synthesis of scutellarein by hydrolyzing scutellarin. The in vitro antioxidant activities of scutellarein were evaluated by measuring its scavenging capacities toward DPPH, ABTS^+•, ^•OH free radicals and its protective effect on H₂O₂-induced cytotoxicity in PC12 cells using MTT assay method. The results showed that essential point to the synthesis was the implementation of H₂SO₄ in 90% ethanol in N₂ atmosphere; scutellarein had stronger antioxidant activity than scutellarin. The results have laid the foundation for further research and the development of scutellarein as a promising candidate for ischemic cerebrovascular disease.

SCH58261 the selective adenosine A(2A) receptor blocker modulates ischemia reperfusion injury following bilateral carotid occlusion: role of inflammatory mediators

In the present study, the effects of SCH58261, a selective adenosine A(2A) receptor antagonist that crosses the blood brain barrier (BBB) and 8-(4-sulfophenyl) theophylline (8-SPT), a non-selective adenosine receptor antagonist that acts peripherally, were investigated on cerebral ischemia reperfusion injury (IR). Male Wistar rats (200-250 g) were divided into four groups: (1) sham-operated (SO), IR pretreated with either (2) vehicle (DMSO); (3) SCH58261 (0.01 mg/kg); (4) 8-SPT (2.5 mg/kg). Animals were anesthetized and submitted to occlusion of both carotid arteries for 45 min. All treatments were administered intraperitoneally (i.p.) post carotid occlusion prior to exposure to a 24 h reperfusion period. Ischemic rats showed increased infarct size compared to their control counterparts that corroborated with histopathological changes as well as increased lactate dehydrogenase (LDH) activity in the hippocampus. Moreover, ischemic animals showed habituation deficit, increased anxiety and locomotor activity. IR increased hippocampal glutamate (Glu), GABA, glycine (Gly) and aspartate (ASP). SCH58261 significantly reversed these effects while 8-SPT elicited minimal change. IR raised myeloperoxidase (MPO), tumor necrosis factor-alpha (TNF-α), nitric oxide (NO), prostaglandin E₂ (PGE₂) accompanied by a decrease in interleukin-10 (IL-10), effects that were again reversed by SCH58261, but 8-SPT elicited less changes. Results from the present study point towards the importance of central blockade of adenosine A(2A) receptor in ameliorating hippocampal damage following IR injury by halting inflammatory cascades as well as modulating excitotoxicity.

Aged garlic extract attenuates cerebral damage and cyclooxygenase-2 induction after ischemia and reperfusion in rats

Different garlic products reduce the cerebral ischemic damage due to their antioxidant properties. In this work, we investigated the effect of aged garlic extract (AGE) on cyclooxygenase-2 (COX-2) protein levels and activity, and its role as a possible mechanism of neuroprotection in a cerebral ischemia model. Animals were subjected to 1 h of ischemia plus 24 h of reperfusion. AGE (1.2 ml/kg weight, i.p.) was administered at onset of reperfusion. To evaluate the damage induced by cerebral ischemia, the neurological deficit, the infarct area, and the histological alterations were measured. As an oxidative stress marker to deoxyribonucleic acid, 8-hydroxy-2-deoxyguanosine (8-OHdG) levels were determined. Finally, as inflammatory markers, TNFα levels and COX-2 protein levels and activity were measured. AGE treatment diminished the neurological alterations (61.6%), the infarct area (54.8%) and the histological damage (37.7%) induced by cerebral ischemia. AGE administration attenuated the increase in 8-OHdG levels (77.8%), in TNFα levels (76.6%), and in COX-2 protein levels (73.6%) and activity (30.7%) induced after 1 h of ischemia plus 24 h of reperfusion. These data suggest that the neuroprotective effect of AGE is associated not only to its antioxidant properties, but also with its capacity to diminish the increase in TNFα levels and COX-2 protein expression and activity. AGE may have the potential to attenuate the cerebral ischemia-induced inflammation.

Differential aquaporin 4 expression during edema build-up and resolution phases of brain inflammation

Background

Vasogenic edema dynamically accumulates in many brain disorders associated with brain inflammation, with the critical step of edema exacerbation feared in patient care. Water entrance through blood-brain barrier (BBB) opening is thought to have a role in edema formation. Nevertheless, the mechanisms of edema resolution remain poorly understood. Because the water channel aquaporin 4 (AQP4) provides an important route for vasogenic edema resolution, we studied the time course of AQP4 expression to better understand its potential effect in countering the exacerbation of vasogenic edema.

Methods

Focal inflammation was induced in the rat brain by a lysolecithin injection and was evaluated at 1, 3, 7, 14 and 20 days using a combination of in vivo MRI with apparent diffusion coefficient (ADC) measurements used as a marker of water content, and molecular and histological approaches for the quantification of AQP4 expression. Markers of active inflammation (macrophages, BBB permeability, and interleukin-1β) and markers of scarring (gliosis) were also quantified.

Results

This animal model of brain inflammation demonstrated two phases of edema development: an initial edema build-up phase during active inflammation that peaked after 3 days (ADC increase) was followed by an edema resolution phase that lasted from 7 to 20 days post injection (ADC decrease) and was accompanied by glial scar formation. A moderate upregulation in AQP4 was observed during the build-up phase, but a much stronger transcriptional and translational level of AQP4 expression was observed during the secondary edema resolution phase.

Conclusions

We conclude that a time lag in AQP4 expression occurs such that the more significant upregulation was achieved only after a delay period. This change in AQP4 expression appears to act as an important determinant in the exacerbation of edema, considering that AQP4 expression is insufficient to counter the water influx during the build-up phase, while the second more pronounced but delayed upregulation is involved in the resolution phase. A better pathophysiological understanding of edema exacerbation, which is observed in many clinical situations, is crucial in pursuing new therapeutic strategies.

Lutein enhances survival and reduces neuronal damage in a mouse model of ischemic stroke

INTRODUCTION

Stroke is one of the leading causes of death worldwide. Protective agents that could diminish the injuries induced by cerebral ischemia/reperfusion (I/R) are crucial to alleviate the detrimental outcome of stroke. The aim of this study is to investigate the protective roles of lutein in cerebral I/R injury.

METHODS

Two-hour cerebral ischemia was induced by unilateral middle cerebral artery occlusion (MCAo) in mice. Either lutein (0.2 mg/kg) or vehicle was given to mice intraperitoneally 1h after MCAo and 1h after reperfusion. Neurological deficits were evaluated at 22 h after reperfusion while survival rate was assessed daily until 7 days after reperfusion. Brains were cut into 2mm-thick coronal slices and stained with 2% 2,3,5-triphenyltetrazolium chloride to determine the infarct size after MCAo. Paraffin-embedded brain sections were prepared for TUNEL assay and immunohistochemistry. Protein lysate was collected for Western blotting experiments.

RESULTS

Higher survival rate, better neurological scores, smaller infarct area and smaller infarct volume were noted in the lutein-treated group. Immunohistochemistry data showed a decrease of immunoreactivity of nitrotyrosine, poly(ADP-ribose) and NFκB in the lutein-treated brains. Western blotting data showed decreased levels of Cox-2, pERK, and pIκB, but increased levels of Bcl-2, heat shock protein 70 and pAkt in the lutein-treated brains.

CONCLUSIONS

Post-treatment of lutein protected the brain from I/R injury, probably by its anti-apoptotic, anti-oxidative and anti-inflammatory properties. These suggest that lutein could diminish the deleterious outcomes of cerebral I/R and may be used as a potential treatment for stroke patients.

Comparison of humoral neuroinflammation and adhesion molecule expression in two models of experimental intracerebral hemorrhage

Background

Inflammatory cascades contribute to secondary injury after intracerebral hemorrhage (ICH) via humoral factors and cell-mediated cytotoxicity. Several experimental models were previously developed to analyze post-hemorrhagic neuroinflammation. However, neuroinflammatory markers have not been compared face-to-face between these models so far, and therefore, pathophysiological conclusions drawn from only one individual model may not be valid.

Methods

We compared neuroinflammatory pathways in the two most common murine models: striatal injection of autologous blood or collagenase. Expression of pro- and anti-inflammatory cytokines (IL-1, TNF-α, IFN-γ, IL-6, TGF-β and IL-10) as well adhesion molecule expression (VCAM-1, ICAM-1) was analyzed by RT-PCR at several time points after ICH induction. Outcome and physiological parameters were compared between the models.

Results

Both models induced a profound and dynamic increase in the expression of pro-inflammatory cytokines and adhesion molecules. However, blood injection resulted in significantly more pronounced alteration of these markers than collagenase injection. This difference was associated with worse outcome after blood injection compared to the collagenase model despite equal ICH volumes.

Conclusions

This is the first study performing a face-to-face comparison of neuroinflammatory pathways in the two most widely used murine ICH models, revealing substantial differences between the models. This discrepancies need to be taken into account in designing future studies employing experimental ICH models, especially when analyzing neuroinflammatory pathways and therapies.

The effect of NeuroAiD™ (MLC601) on cerebral blood flow velocity in subjects' post brain infarct in the middle cerebral artery territory

BACKGROUND

Stroke is the third common cause of mortality and the most common cause of morbidity in adults. MLC601 (NeuroAiD™) is a treatment indicated for post stroke recovery. An increase of impaired cerebral blood flow may be an important parameter for recovery processes. The aim of this study was to investigate the effect of MLC601 on cerebral blood flow velocity as an indirect evidence of cerebral blood flow increase in post stroke subjects.

METHODS

This is a double-blinded, placebo controlled, randomized study of 80 subjects included within a week of stroke onset. All subjects were given either MLC601 or placebo, 4 capsules, 3 times a day for 3 months. Cerebral blood flow within the middle cerebral artery, with blood flow velocity measured by transcranial Doppler (TCD), and Barthel index was assessed at baseline and at 3 months.

RESULTS

The mean change in cerebral blood flow velocity in the MLC601 treatment group (15.9) was significantly increased (p=0.009) compared to the placebo group (9.6). Subjects in the treatment group also showed a significant difference in the mean rank of modified ranking scale (p<0.001) and mean change of the Barthel Index: 36 vs. 29 in the placebo group (p<0.001).

CONCLUSION

This is the first study suggesting that treatment with MLC601 may increase cerebral blood flow in stroke subjects. This may be mediated by an effect on stimulating microcirculation, an important process contributing to neuroplasticity in the central nervous system. This effect on cerebral blood flow may be associated with improvement in measures of functional recovery.

The neuroprotection of oxymatrine in cerebral ischemia/reperfusion is related to nuclear factor erythroid 2-related factor 2 (nrf2)-mediated antioxidant response: role of nrf2 and hemeoxygenase-1 expression

Cerebral ischemia-reperfusion (CI/R) injury remains a major medical problem due to the lack of effective therapies. Previous studies have shown that increasing the activity of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and gene targets in cell culture and stroke animal models is highly neuroprotective. Oxymatrine is the major quinolizidine alkaloid extracted from the root of Sophora flavescens AIT, and has been proved to be protective after ischemia in recent studies. The present study was designed to investigate the potential effect of oxymatrine in ischemia-reperfusion injury in rat's brain and to explore the possible role of oxymatrine in Nrf2 pathway. The results indicated that the ischemic infarct and edema were significantly reduced in rats that received oxymatrine, with a corresponding improvement in neurological function after CI/R. In immunohistochemistry and Western blotting analyses, Nrf2 and hemeoxygenase-1 (HO-1) were up-regulated in ischemic cortex, beginning at 6 h, peaking at 48 h and declining at 72 h after CI/R. Intraperitoneal injection of oxymatrine inhibited the production of lipid peroxidation and increased the activities of Nrf2 and HO-1 in rats brain after CI/R. Taken together, these results suggest that oxymatrine administered systemically protected brain against focal ischemia-reperfusion damage at the early stage of stroke, and that activating Nrf2/HO-1 pathway may contribute to the neuroprotective action of oxymatrine in rat focal brain ischemia-reperfusion model. Thus, treatment of stroke with oxymatrine may prevent severe consequences after brain attack.

Calorie restriction and stroke

Stroke, a major cause of disability and mortality in the elderly, occurs when a cerebral blood vessel is occluded or ruptured, resulting in ischemic damage and death of brain cells. The injury mechanism involves metabolic and oxidative stress, excitotoxicity, apoptosis and inflammatory processes, including activation of glial cells and infiltration of leukocytes. In animal models, dietary energy restriction, by daily calorie reduction (CR) or intermittent fasting (IF), extends lifespan and decreases the development of age-related diseases. Dietary energy restriction may also benefit neurons, as suggested by experimental evidence showing that CR and IF protect neurons against degeneration in animal models. Recent findings by our group and others suggest the possibility that dietary energy restriction may protect against stroke induced brain injury, in part by inducing the expression of neurotrophic factors, such as brain-derived neurotrophic factor (BDNF) and basic fibroblast growth factor (bFGF); protein chaperones, including heat shock protein 70 (Hsp70) and glucose regulated protein 78 (GRP78); antioxidant enzymes, such as superoxide dismutases (SOD) and heme oxygenase-1 (HO-1), silent information regulator T1 (SIRT1), uncoupling proteins and anti-inflammatory cytokines. This article discusses the protective mechanisms activated by dietary energy restriction in ischemic stroke.

Oxidative stress and blood-brain barrier dysfunction under particular consideration of matrix metalloproteinases

A cell's "redox" (oxidation and reduction) state is determined by the sum of all redox processes yielding reactive oxygen species (ROS), reactive nitrogen species (RNS), and other reactive intermediates. Low amounts of ROS/RNS are generated by different mechanisms in every cell and are important regulatory mediators in many signaling processes (redox signaling). When the physiological balance between the generation and elimination of ROS/RNS is disrupted, oxidative/nitrosative stress with persistent oxidative damage of the organism occurs. Oxidative stress has been suggested to act as initiator and/or mediator of many human diseases. The cerebral vasculature is particularly susceptible to oxidative stress, which is critical since cerebral endothelial cells play a major role in the creation and maintenance of the blood-brain barrier (BBB). This article will only contain a focused introduction on the biochemical background of redox signaling, since this has been reported already in a series of excellent recent reviews. The goal of this work is to increase the understanding of basic mechanisms underlying ROS/RNS-induced BBB disruption, with a focus on the role of matrix metalloproteinases, which, after all, appear to be a key mediator in the initiation and progression of BBB damage elicited by oxidative stress.