Inflammatory mechanisms in ischemic stroke: therapeutic approaches

The microglial α7-acetylcholine nicotinic receptor is a key element in promoting neuroprotection by inducing heme oxygenase-1 via nuclear factor erythroid-2-related factor 2

AIMS

We asked whether the neuroprotective effect of cholinergic microglial stimulation during an ischemic event acts via a mechanism involving the activation of nuclear factor erythroid-2-related factor 2 (Nrf2) and/or the expression of its target cytoprotective gene, heme oxygenase-1 (HO-1). Specifically, the protective effect of the pharmacologic alpha-7 nicotinic acetylcholine receptor (α7 nAChR) agonist PNU282987 was analyzed in organotypic hippocampal cultures (OHCs) subjected to oxygen and glucose deprivation (OGD) in vitro as well as in photothrombotic stroke in vivo.

RESULTS

OHCs exposed to OGD followed by reoxygenation elicited cell death, measured by propidium iodide and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide staining. Activation of α7 nAChR by PNU282987, after OGD, reduced cell death, reactive oxygen species production, and tumor necrosis factor release. This was associated with induction of HO-1 expression, an effect reversed by α-bungarotoxin and by tin-protoporphyrin IX. The protective effect of PNU282987 was lost in microglial-depleted OHCs as well as in OHCs from Nrf2-deficient-versus-wild-type mice, an effect associated with suppression of HO-1 expression in microglia. Administration of PNU282987 1 h after induction of photothrombotic stroke in vivo reduced the infarct size and improved motor skills in Hmox1(lox/lox) mice that express normal levels of HO-1, but not in LysM(Cre)Hmox1(Δ/Δ) in which HO-1 expression is inhibited in myeloid cells, including the microglia.

INNOVATION

This study suggests the participation of the microglial α7 nAChR in the brain cholinergic anti-inflammatory pathway.

CONCLUSION

Activation of the α7 nAChR/Nrf2/HO-1 axis in microglia regulates neuroinflammation and oxidative stress, affording neuroprotection under brain ischemic conditions.

Therapeutic potential of amniotic fluid-derived cells for treating the injured nervous system

There is a need for improved therapy for acquired brain injury, which has proven resistant to treatment by numerous drugs in clinical trials and continues to represent one of the leading causes of disability worldwide. Research into cell-based therapies for the treatment of brain injury is growing rapidly, but the ideal cell source has yet to be determined. Subpopulations of cells found in amniotic fluid, which is readily obtained during routine amniocentesis, can be easily expanded in culture, have multipotent differentiation capacity, are non-tumourigenic, and avoid the ethical complications associated with embryonic stem cells, making them a promising cell source for therapeutic purposes. Beneficial effects of amniotic fluid cell transplantation have been reported in various models of nervous system injury. However, evidence that amniotic fluid cells can differentiate into mature, functional neurons in vivo and incorporate into the existing circuitry to replace lost or damaged neurons is lacking. The mechanisms by which amniotic fluid cells improve outcomes after experimental nervous system injury remain unclear. However, studies reporting the expression and release of neurotrophic, angiogenic, and immunomodulatory factors by amniotic fluid cells suggest they may provide neuroprotection and (or) stimulate endogenous repair and remodelling processes in the injured nervous system. In this paper, we address recent research related to the neuronal differentiation of amniotic fluid-derived cells, the therapeutic efficacy of these cells in animal models of nervous system injury, and the possible mechanisms mediating the positive outcomes achieved by amniotic fluid cell transplantation.

Changes in Hypothalamus–Pituitary–Adrenal Axis Following Transient Ischemic Attack

Acute brain ischemia caused by transient ischemic attack initiates a complex sequence of events in the central nervous system and hypothalamic–pituitary–adrenal (HPA) axis which may ultimately culminate in neuronal and cell damage. The brain is highly susceptible to ischemia and in response to stress shows changes in morphology and chemistry that are largely reversible. These responses are known to modify the function of the HPA axis, but their mechanisms are not yet clear. Duration and size of the HPA axis activation are regulated by corticotropin-releasing hormone, vasopressin (AVP), and glucocorticoids, including cortisol. Numerous studies suggest that activation of these hormones following brain ischemia can result in neurohormonal dysfunction that can exacerbate long-term prognosis following stroke. These studies represent evidence that changes in the HPA axis play an important role in brain ischemia.

Leukocyte infiltration in experimental stroke

Stroke is one of the leading causes of death worldwide. At present, the only available treatment is thrombolysis, which should be initiated no later than 4.5 hours after onset of symptoms. Several studies have shown that an attenuation of the inflammatory response in relation to stroke could widen the therapeutic window. However, the immune system has important functions following infarction, such as removal of dead cells and the subsequent astrocytosis as well as prevention of post-ischemic infection. Hence, detailed knowledge concerning the temporal profile of leukocyte infiltration is necessary in order to develop new and effective treatments.

The purpose of this review is to determine the temporal profile of leukocyte (neutrophil granulocytes, macrophages and T-cells) infiltration following experimental stroke. We found that the number of neutrophil granulocytes peaks between day 1 and 3 after experimental stroke, with short occlusion times (30 and 60 minutes of middle cerebral artery occlusion (MCAO)) leading to a later peak in response (P <0.001). Macrophages/microglia were found to peak later than day 3 and stay in the infarcted area for longer time periods, whereas duration of occlusion had no influence on the temporal infiltration (P = 0.475). Studies on T-cell infiltration are few; however, a tendency towards infiltration peak at later time points (from day 4 onwards) was seen.

This review provides a framework for the instigation of post-stroke anti-inflammatory treatment, which could prove beneficial and widen the therapeutic window compared to current treatment options.

Neuroprotection by gonadal steroid hormones in acute brain damage requires cooperation with astroglia and microglia

The neuroactive steroids 17β-estradiol and progesterone control a broad spectrum of neural functions. Besides their roles in the regulation of classical neuroendocrine loops, they strongly influence motor and cognitive systems, behavior, and modulate brain performance at almost every level. Such a statement is underpinned by the widespread and lifelong expression pattern of all types of classical and non-classical estrogen and progesterone receptors in the CNS. The life-sustaining power of neurosteroids for tattered or seriously damaged neurons aroused interest in the scientific community in the past years to study their ability for therapeutic use under neuropathological challenges. Documented by excellent studies either performed in vitro or in adequate animal models mimicking acute toxic or chronic neurodegenerative brain disorders, both hormones revealed a high potency to protect neurons from damage and saved neural systems from collapse. Unfortunately, neurons, astroglia, microglia, and oligodendrocytes are comparably target cells for both steroid hormones. This hampers the precise assignment and understanding of neuroprotective cellular mechanisms activated by both steroids. In this article, we strive for a better comprehension of the mutual reaction between these steroid hormones and the two major glial cell types involved in the maintenance of brain homeostasis, astroglia and microglia, during acute traumatic brain injuries such as stroke and hypoxia. In particular, we attempt to summarize steroid-activated cellular signaling pathways and molecular responses in these cells and their contribution to dampening neuroinflammation and neural destruction. This article is part of a Special Issue entitled 'CSR 2013'.

Intranasal pyrrolidine dithiocarbamate decreases brain inflammatory mediators and provides neuroprotection after brain hypoxia-ischemia in neonatal rats

Brain injury due to birth asphyxia is the major cause of death and long-term disabilities in newborns. We determined whether intranasal pyrrolidine dithiocarbamate (PDTC) could provide neuroprotection in neonatal rats after brain hypoxia-ischemia (HI). Seven-day old male and female Sprague-Dawley rats were subjected to brain HI. They were then treated with intranasal PDTC. Neurological outcomes were evaluated 7 or 30 days after the brain HI. Brain tissues were harvested 6 or 24 h after the brain HI for biochemical analysis. Here, PDTC dose-dependently reduced brain HI-induced brain tissue loss with an effective dose (ED)50 at 27 mg/kg. PDTC needed to be applied within 45 min after the brain HI for this neuroprotection. This treatment reduced brain tissue loss and improved neurological and cognitive functions assessed 30 days after the HI. PDTC attenuated brain HI-induced lipid oxidative stress, nuclear translocation of nuclear factor κ-light-chain-enhancer of activated B cells, and various inflammatory mediators in the brain tissues. Inhibition of inducible nitric oxide synthase after brain HI reduced brain tissue loss. Our results suggest that intranasal PDTC provides neuroprotection possibly via reducing inflammation and oxidative stress. Intranasal PDTC may have a potential to provide neuroprotection to human neonates after birth asphyxia.

Oxidative damage in clinical ischemia/reperfusion injury: a reappraisal

AIMS

Ischemia/reperfusion (I/R) injury is a common clinical problem. Although the pathophysiological mechanisms underlying I/R injury are unclear, oxidative damage is considered a key factor in the initiation of I/R injury. Findings from preclinical studies consistently show that quenching reactive oxygen and nitrogen species (RONS), thus limiting oxidative damage, alleviates I/R injury. Results from clinical intervention studies on the other hand are largely inconclusive. In this study, we systematically evaluated the release of established biomarkers of oxidative and nitrosative damage during planned I/R of the kidney and heart in a wide range of clinical conditions.

RESULTS

Sequential arteriovenous concentration differences allowed specific measurements over the reperfused organ in time. None of the biomarkers of oxidative and nitrosative damage (i.e., malondialdehyde, 15(S)-8-iso-prostaglandin F2α, nitrite, nitrate, and nitrotyrosine) were released upon reperfusion. Cumulative urinary measurements confirmed plasma findings. As of these negative findings, we tested for oxidative stress during I/R and found activation of the nuclear factor erythroid 2-related factor 2 (Nrf2), the master regulator of oxidative stress signaling.

INNOVATION

This comprehensive, clinical study evaluates the role of RONS in I/R injury in two different human organs (kidney and heart). Results show oxidative stress, but do not provide evidence for oxidative damage during early reperfusion, thereby challenging the prevailing paradigm on RONS-mediated I/R injury.

CONCLUSION

Findings from this study suggest that the contribution of oxidative damage to human I/R may be less than commonly thought and propose a re-evaluation of the mechanism of I/R.

Brazilian green propolis suppresses the hypoxia-induced neuroinflammatory responses by inhibiting NF-κB activation in microglia

Hypoxia has been recently proposed as a neuroinflammatogen, which drives microglia to produce proinflammatory cytokines, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6. Considering the fact that propolis has hepatoprotective, antitumor, antioxidative, and anti-inflammatory effects, propolis may have protective effects against the hypoxia-induced neuroinflammatory responses. In this study, propolis (50 μg/mL) was found to significantly inhibit the hypoxia-induced cytotoxicity and the release of proinflammatory cytokines, including IL-1β, TNF-α, and IL-6, by MG6 microglia following hypoxic exposure (1% O2, 24 h). Furthermore, propolis significantly inhibited the hypoxia-induced generation of reactive oxygen species (ROS) from mitochondria and the activation of nuclear factor-κB (NF-κB) in microglia. Moreover, systemic treatment with propolis (8.33 mg/kg, 2 times/day, i.p.) for 7 days significantly suppressed the microglial expression of IL-1β, TNF-α, IL-6, and 8-oxo-deoxyguanosine, a biomarker for oxidative damaged DNA, in the somatosensory cortex of mice subjected to hypoxia exposure (10% O2, 4 h). These observations indicate that propolis suppresses the hypoxia-induced neuroinflammatory responses through inhibition of the NF-κB activation in microglia. Furthermore, increased generation of ROS from the mitochondria is responsible for the NF-κB activation. Therefore, propolis may be beneficial in preventing hypoxia-induced neuroinflammation.

Downregulation of miR-181b in mouse brain following ischemic stroke induces neuroprotection against ischemic injury through targeting heat shock protein A5 and ubiquitin carboxyl-terminal hydrolase isozyme L1

Understanding the molecular mechanism of cerebral hypoxic preconditioning (HPC)-induced endogenous neuroprotection may provide potential therapeutic targets for ischemic stroke. By using bioinformatics analysis, we found that miR-181b, one of 19 differentially expressed miRNAs, may target aconitate hydratase (ACO2), heat shock protein A5 (HSPA5), and ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1) among 26 changed protein kinase C isoform-specific interacting proteins in HPC mouse brain. In this study, the role of miR-181b in oxygen-glucose deprivation (OGD)-induced N2A cell ischemic injury in vitro and mouse middle cerebral artery occlusion (MCAO)-induced cerebral ischemic injury in vivo, and its regulation of ACO2, HSPA5, and UCHL1 were further determined. We found that miR-181b expression levels significantly decreased in mouse brain following MCAO and in OGD-treated N2A cells. Up- and downregulation of miR-181b by transfection of pre- or anti-miR-181b could negatively regulate HSPA5 and UCHL1 (but not ACO2) protein levels as well as N2A cell death and programmed cell death in OGD-treated N2A cells. By using a T7 promoter-driven control dual luciferase assay, we confirmed that miR-181b could bind to the 3'-untranslated rergions of HSPA5 and UCHL1 mRNAs and repress their translations. miR-181b antagomir reduced caspase-3 cleavage and neural cell loss in cerebral ischemic cortex and improved neurological deficit of mice after MCAO. In addition, HSPA5 and UCHL1 short interfering RNAs (siRNAs) blocked anti-miR-181b-mediated neuroprotection against OGD-induced N2A cell injury in vitro. These results suggest that the downregulated miR-181b induces neuroprotection against ischemic injury through negatively regulating HSPA5 and UCHL1 protein levels, providing a potential therapeutic target for ischemic stroke.

Fundamental research progress of mild hypothermia in cerebral protection

Through the years, the clinical application of mild hypothermia has been carried out worldwide and is built from the exploration and cognition of neuroprotection mechanisms by hypothermia. However, within the last decade, extensive and fundamental researches in this area have been conducted. In addition to aspects of the previous findings, scholars have discovered several new contents and uncertain results. This article reviews and summarizes this decade’s progression of mild hypothermia in lowering the cerebral oxygen metabolism, protecting the blood–brain-barrier, regulating the inflammatory response, regulating the excessive release of neurotransmitters, inhibiting calcium overload, and reducing neuronal apoptosis. In many aspects, particularly in regulating inflammatory reverse reaction, various results have been reported and therefore guide scholars to conduct more detailed analysis and investigation in order to discover the inherent theories surrounding the effect of mild hypothermia, and for better clinical services.

Stromal derived growth factor-1 (CXCL12) modulates synaptic transmission to immature neurons during post-ischemic cerebral repair

In response to ischemic injury, the brain mounts a repair process involving the development of new neurons, oligodendrocytes, and astrocytes. However, the manner in which new neurons integrate into existing brain circuitry is not well understood. Here we observed that during the four weeks after transient middle cerebral artery occlusion (MCAO), doublecortin (DCX)-expressing neural progenitors originating in the subventricular zone (SVZ) were present in the ischemic lesion borderzone, where they received γ-aminobutyric acid (GABA) inputs, a feature that is common to newly developing neurons. The chemokine stromal derived factor-1 (SDF-1 or CXCL12) was enriched in lesional endothelial and microglial cells for up to four weeks after transient MCAO, and application of SDF-1 to acute brain slices enhanced GABAergic inputs to the new neurons. These observations suggest that SDF-1 is in a position to coordinate neovascularization and neurogenesis during the repair process after cerebral ischemia-reperfusion.

Impact of early versus late enteral nutrition on cell mediated immunity and its relationship with glucagon like peptide-1 in intensive care unit patients: a prospective study

Introduction

Glucagon-like peptide-1 (GLP-1) originates from the gastrointestinal system in response to the presence of nutrition in the intestinal lumen and potentiates postprandial insulin secretion. Also, it acts as an immune-modulator which has influences on cell-mediated immunity.

The aim of this study was to determine the impact of early enteral nutrition versus late enteral nutrition on plasma GLP-1 levels and the relationship between GLP-1 changes and cell-mediated immunity.

Materials and methods

The study was designed as a prospective, single-blinded study and carried out in the neurology intensive care unit (ICU) of a university hospital. Twenty-four naive patients with acute thromboembolic cerebrovascular events, with National Institute of Health (NIH) stroke scores between 12 and 16, were included. Any condition interfering with GLP-1 and immunity was regarded as exclusion criterion. Two patients died, and two dropped out of the study due to complicating conditions.

Patients were randomly subjected to early enteral feeding within the first 24 hours (Group 1), or late enteral feeding, beginning 48 hours after admission (Group 2) via a nasogastric tube. Calculated daily energy requirement was supplemented with parenteral nutrition, starting on the first study day for both groups. Blood samples were obtained before, and at 5, 15, 30, 60 and 120 minutes after the first enteral feeding for GLP-1 assays; this procedure was repeated on the third day. Before and 24 hours after the first enteral feeding, samples were also taken for immunological analysis. Clinical observations were recorded.

Pre- and post-feeding plasma GLP-1 changes between the two groups and within groups were evaluated. Lymphocyte subgroup changes before and 24 hours after the first enteral feeding in relation to GLP-1 changes were sought as well.

Results

Group 1 and Group 2 exhibited similar GLP-1 levels in the pre-feeding and post-feeding periods for both the first time and the third day of enteral feeding. Also, no significant change in pre-/post-feeding GLP-1 levels was observed within groups. T-helper and T-regulatory cells increased, T-cytotoxic cells decreased significantly in Group 1 (P = 0.02; P = 0.036; P = 0.0019), but remained the same in Group 2 after enteral feeding. Positive but statistically insignificant clinical effects in terms of predisposition to infections (10% vs 40%) and median time of ICU stay (10 vs 15 days) were observed in Group 1.

Conclusions

Depending on our findings, we propose that early enteral feeding may cause amelioration in cell-mediated immunity via factors other than GLP-1 in ICU patients with acute thromboembolic stroke. However, the possible deleterious effects of parenteral nutrition cannot be ruled out.

Immune following suppression mesenchymal stem cell transplantation in the ischemic brain is mediated by TGF-β

Transplantation of mesenchymal stem cells (MSCs) has been shown to enhance the recovery of brain functions following ischemic injury. Although immune modulation has been suggested to be one of the mechanisms, the molecular mechanisms underlying improved recovery has not been clearly identified. Here, we report that MSCs secrete transforming growth factor-beta (TGF-β) to suppress immune propagation in the ischemic rat brain. Ischemic stroke caused global death of resident cells in the infarcted area, elevated the monocyte chemoattractant protein-1 (MCP-1) level, and evoked massive infiltration of circulating CD68+ immune cells through the impaired blood-brain barrier. Transplantation of MSCs at day 3 post-ischemia blocked the subsequent upregulation of MCP-1 in the ischemic area and the infiltration of additional CD68+ immune cells. MSC-conditioned media decreased the migration and MCP-1 production of freshly isolated immune cells in vitro, and this effect was blocked by an inhibitor of TGF-β signaling or an anti-TGF-β neutralizing antibody. Finally, transplantation of TGF-β1-silenced MSCs failed to attenuate the infiltration of CD68+ cells into the ischemic brain, and was associated with only minor improvements in motor function. These results indicate that TGF-β is key to the ability of MSCs to beneficially attenuate immune reactions in the ischemic brain. Our findings offer insight into the interactions between allogeneic MSCs and the host immune system, reinforcing the prospective clinical value of using MSCs in the treatment of neurological disorders involving inflammation-mediated secondary damage.

Phycocyanobilin promotes PC12 cell survival and modulates immune and inflammatory genes and oxidative stress markers in acute cerebral hypoperfusion in rats

Since the inflammatory response and oxidative stress are involved in the stroke cascade, we evaluated here the effects of Phycocyanobilin (PCB, the C-Phycocyanin linked tetrapyrrole) on PC12 cell survival, the gene expression and the oxidative status of hypoperfused rat brain. After the permanent bilateral common carotid arteries occlusion (BCCAo), the animals were treated with saline or PCB, taking samples 24h post-surgery. Global gene expression was analyzed with GeneChip Rat Gene ST 1.1 from Affymetrix; the expression of particular genes was assessed by the Fast SYBR Green RT-PCR Master Mix and Bioplex methods; and redox markers (MDA, PP, CAT, SOD) were evaluated spectrophotometrically. The PCB treatment prevented the H2O2 and glutamate induced PC12 cell injury assessed by the MTT assay, and modulated 190 genes (93 up- and 97 down-regulated) associated to several immunological and inflammatory processes in BCCAo rats. Furthermore, PCB positively modulated 19 genes mostly related to a detrimental pro-inflammatory environment and counteracted the oxidative imbalance in the treated BCCAo animals. Our results support the view of an effective influence of PCB on major inflammatory mediators in acute cerebral hypoperfusion. These results suggest that PCB has a potential to be a treatment for ischemic stroke for which further studies are needed.

Kir6.1 knockdown aggravates cerebral ischemia/reperfusion-induced neural injury in mice

BACKGROUND AND PURPOSE

ATP-sensitive potassium (K-ATP) channels couple energy metabolism with electric activity, which play important roles in brain diseases including stroke. However, the impacts of Kir6.1-containing K-ATP channels that mainly expressed on glia in stroke remain unclear.

METHODS AND RESULTS

In this study, we found that expression of Kir6.1 was significantly decreased in the ischemic brain area of C57BL/6J mice after 1-h middle cerebral artery occlusion (MCAO) and 24-h reperfusion. Then, we subjected Kir6.1 heterozygote knockout (Kir6.1(+/-) ) mice to cerebral ischemia/reperfusion (I/R) injury and found that Kir6.1(+/-) mice exhibited exacerbated neurological disorder and enlarged infarct size, companied by glial over-activation and blood-brain barrier (BBB) damages. Furthermore, we showed that Kir6.1 knockdown aggravated endoplasmic reticulum (ER) stress and thereby increased the levels of proinflammatory factors tumor necrosis factor-α and interleukin-1β (TNF-α and IL-1β) in mouse brain.

CONCLUSIONS

Our findings reveal that Kir6.1 knockdown exacerbates cerebral I/R-induced brain damages via increasing ER stress and inflammatory response, indicating that Kir6.1-containing K-ATP channels may be a potential therapeutic target for stroke.

Pro-inflammatory cytokine network in peripheral inflammation response to cerebral ischemia

The key circulating pro-inflammatory cytokines and their interaction in peripheral inflammation after acute cerebral ischemia are poorly understood. CD40L, IFN-γ, IL-1α, IL-1β, IL-6, IL-8, IL-17 and TNF-α were determined using multi-ELISA kit in stroke patients within 72 h of an acute ischemic attack. Leukocyte mRNAs were determined using real-time polymerase chain reactions (PCR). Stroke severity and clinical outcomes were evaluated by National Institutes of Health Stroke Scores (NIHSS) and modified Rankin Scale (mRS). Plasma/mRNA cytokine interactions were analyzed using the Bayesian network learning procedure. Compared to controls, stroke patients had higher IL-6, IL-8 and TNFα protein in plasma and lower IL-6, IL-8, TNFα, IL-1α, and IL-1β mRNA in leukocyte within 72 h after stroke. However, only the elevation of IL-6 correlated with the severity and prognosis of their stroke. This was associated with a decreased IL-6 mRNA in leukocyte. Further study showed that Bayesian network analysis revealed that changes in the other cytokines were subsequent to IL-6 leukocyte cytokine RNA. The change of other cytokines in plasma proteins after ischemic brain injury appeared secondary to IL-6. Pro-inflammatory cytokines up-regulation in plasma and compensatory immunity depression in leukocyte involve in peripheral inflammation response to cerebral ischemia. IL-6 appears to be the key mediator of circulating pro-inflammatory cytokines network.

Cerebroprotective effect of resveratrol through antioxidant and anti-inflammatory effects in diabetic rats

Oxidative stress and inflammation have been implicated in cerebral ischemia/reperfusion injury and complication of diabetes. The present study was designed to evaluate whether resveratrol has cerebroprotective action through antioxidant and anti-inflammatory actions in diabetic rats. Bilateral common carotid artery occlusion (30 min) and reperfusion (4 h) was employed to induce cerebral infarction in diabetic Wistar rats. Diabetes was induced by streptozocine (50 mg/kg) intraperitoneally at once. Diabetic animals were divided into groups as: normal, sham, ischemia-reperfusion, and resveratrol-treated (5, 10, 20, and 30 mg/kg). These were used for estimation of cerebral infarction. Furthermore, 20 mg/kg dose was selected for estimation of oxidative stress markers (malondialdehyde, superoxide dismutase, and catalase). Inflammatory markers like TNF-α, IL-6, IL-10, and myeloperoxidase were estimated and histological characters were studied. Resveratrol produced dose-dependent reduction in percent cerebral infarction. With resveratrol of 20 mg/kg dose, levels of oxidative stress markers and inflammatory markers like malondialdehyde, TNF-α, IL-6, and myeloperoxidase were reduced and there was a significant increase in the levels of antioxidant and anti-inflammatory markers like catalase, superoxide dismutase, and IL-10. In the present study, we found that mechanism(s) responsible for the cerebroprotective effect of resveratrol in the diabetic rat brain involves antioxidant and anti-inflammatory actions.

Nitric oxide donors as neuroprotective agents after an ischemic stroke-related inflammatory reaction

Cerebral ischemia initiates a cascade of detrimental events including glutamate-associated excitotoxicity, intracellular calcium accumulation, formation of Reactive oxygen species (ROS), membrane lipid degradation, and DNA damage, which lead to the disruption of cellular homeostasis and structural damage of ischemic brain tissue. Cerebral ischemia also triggers acute inflammation, which exacerbates primary brain damage. Therefore, reducing oxidative stress (OS) and downregulating the inflammatory response are options that merit consideration as potential therapeutic targets for ischemic stroke. Consequently, agents capable of modulating both elements will constitute promising therapeutic solutions because clinically effective neuroprotectants have not yet been discovered and no specific therapy for stroke is available to date. Because of their ability to modulate both oxidative stress and the inflammatory response, much attention has been focused on the role of nitric oxide donors (NOD) as neuroprotective agents in the pathophysiology of cerebral ischemia-reperfusion injury. Given their short therapeutic window, NOD appears to be appropriate for use during neurosurgical procedures involving transient arterial occlusions, or in very early treatment of acute ischemic stroke, and also possibly as complementary treatment for neurodegenerative diseases such as Parkinson or Alzheimer, where oxidative stress is an important promoter of damage. In the present paper, we focus on the role of NOD as possible neuroprotective therapeutic agents for ischemia/reperfusion treatment.

Gemfibrozil pretreatment affecting antioxidant defense system and inflammatory, but not Nrf-2 signaling pathways resulted in female neuroprotection and male neurotoxicity in the rat models of global cerebral ischemia-reperfusion

Two important pathophysiological mechanisms involved during cerebral ischemia are oxidative stress and inflammation. In pathological conditions such as brain ischemia the ability of free radicals production is greater than that of elimination by endogenous antioxidative systems, so brain is highly injured due to oxidation and neuroinflammation. Fibrates as peroxisome proliferator-activated receptor (PPAR)-α ligands, are reported to have antioxidant and anti-inflammatory actions. In this study, gemfibrozil, a fibrate is investigated for its therapeutic potential against global cerebral ischemia-reperfusion (I/R) injury of male and female rats. This study particularly has focused on inflammatory and antioxidant signaling pathways, such as nuclear factor erythroid-related factor (Nrf)-2, as well as the activity of some endogenous antioxidant agents. It was found that pretreatment of animals with gemfibrozil prior to I/R resulted in a sexually dimorphic outcome. Within females it proved to be protective, modulating inflammatory factors and inducing antioxidant defense system including superoxide dismutase (SOD), catalase, as well as glutathione level. However, Nrf-2 signaling pathway was not affected. It also decreased malondialdehyde level as an index of lipid peroxidation. In contrast, gemfibrozil pretreatment was toxic to males, enhancing the expression of inflammatory factors such as tumor necrosis factor-α, nuclear factor-κB, and cyclooxygenase-2, and decreasing Nrf-2 expression and SOD activity, leading to hippocampal neurodegeneration. Considering that gemfibrozil is a commonly used anti-hyperlipidemic agent in clinic, undoubtedly more investigations are crucial to exactly unravel its sex-dependent neuroprotective/neurodegenerative potential.

Treatment with Evasin-3 reduces atherosclerotic vulnerability for ischemic stroke, but not brain injury in mice

Neutrophilic inflammation might have a pathophysiological role in both carotid plaque rupture and ischemic stroke injury. Here, we investigated the potential benefits of the CXC chemokine-binding protein Evasin-3, which potently inhibits chemokine bioactivity and related neutrophilic inflammation in two mouse models of carotid atherosclerosis and ischemic stroke, respectively. In the first model, the chronic treatment with Evasin-3 as compared with Vehicle (phosphate-buffered saline (PBS)) was investigated in apolipoprotein E-deficient mice implanted of a 'cast' carotid device. In the second model, acute Evasin-3 treatment (5 minutes after cerebral ischemia onset) was assessed in mice subjected to transient left middle cerebral artery occlusion. Although CXCL1 and CXCL2 were upregulated in both atherosclerotic plaques and infarcted brain, only CXCL1 was detectable in serum. In carotid atherosclerosis, treatment with Evasin-3 was associated with reduction in intraplaque neutrophil and matrix metalloproteinase-9 content and weak increase in collagen as compared with Vehicle. In ischemic stroke, treatment with Evasin-3 was associated with reduction in ischemic brain neutrophil infiltration and protective oxidants. No other effects in clinical and histological outcomes were observed. We concluded that Evasin-3 treatment was associated with reduction in neutrophilic inflammation in both mouse models. However, Evasin-3 administration after cerebral ischemia onset failed to improve poststroke outcomes.

Post-stroke immunodeficiency: effects of sensitization and tolerization to brain antigens

Acute onset of cerebrovascular diseases seems to be related to a number of immunological alternations. After the initial pro-inflammatory response to brain ischemia accompanied by systemic inflammatory response syndrome, stroke interferes with function of the innate and the adaptive immune cells, resulting in systemic immunosuppression. Although post-stroke immunodeficiency could predispose patients to life-threatening infections, it could potentially protect brain via reducing autoimmune reaction to the brain antigens. In this paper, we review current knowledge on the immunological alterations after brain ischemia, particularly effects of infection for stimulation of autoimmune response against brain antigens.

The immune modulating properties of the heat shock proteins after brain injury

Inflammation within the central nervous system often accompanies ischemia, trauma, infection, and other neuronal injuries. The immune system is now recognized to play a major role in neuronal cell death due to microglial activation, leukocyte recruitment, and cytokine secretion. The participation of heat shock proteins (Hsps) in the immune response following in brain injury can be seen as an attempt to correct the inflammatory condition. The Hsps comprise various families on the basis of molecular size. One of the most studied is Hsp70. Hsp70 is thought to act as a molecular chaperone that is present in almost intracellular compartments, and function by refolding misfolded or aggregated proteins. Hsps have recently been studied in inflammatory conditions. Hsp70 can both induce and arrest inflammatory reactions and lead to improved neurological outcome in experimental brain injury and ischemia. In this review, we will focus on underlying inflammatory mechanisms and Hsp70 in acute neurological injury.

Tumor necrosis factor receptor-associated factor 5 is an essential mediator of ischemic brain infarction

Tumor necrosis factor receptor-associated factor 5 (TRAF5) is an adaptor protein of the tumor necrosis factor (TNF) receptor superfamily and the interleukin-1 receptor/Toll-like receptor superfamily and plays important roles in regulating multiple signaling pathways. This study was conducted to investigate the role of TRAF5 in the context of brain ischemia/reperfusion (I/R) injury. Transient occlusion of the middle cerebral artery was performed on TRAF5 knockout mice (KO), neuron-specific TRAF5 transgene (TG), and the appropriate controls. Compared with the WT mice, the TRAF5 KO mice showed lower infarct volumes and better outcomes in the neurological tests. A low neuronal apoptosis level, an attenuated blood-brain barrier (BBB) disruption and an inhibited inflammatory response were exhibited in TRAF5 KO mice. TRAF5 TG mice exhibited an opposite phenotype. Moreover, the Akt/FoxO1 signaling pathway was enhanced in the ischemic brains of the TRAF5 KO mice. These results provide the first demonstration that TRAF5 is a critical mediator of I/R injury in an experimental stroke model. The Akt /FoxO1 signaling pathway probably plays an important role in the biological function of TRAF5 in this model.

Neuroprotective effect of kaempferol glycosides against brain injury and neuroinflammation by inhibiting the activation of NF-κB and STAT3 in transient focal stroke

BACKGROUND

Ischemic brain injury is associated with neuroinflammatory response, which essentially involves glial activation and neutrophil infiltration. Transcription factors nuclear factor-κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) contribute to ischemic neuroinflammatory processes and secondary brain injury by releasing proinflammatory mediators. Kaempferol-3-O-rutinoside (KRS) and kaempferol-3-O- glucoside (KGS) are primary flavonoids found in Carthamus tinctorius L. Recent studies demonstrated that KRS protected against ischemic brain injury. However, little is known about the underlying mechanisms. Flavonoids have been reported to have antiinflammatory properties. Herein, we explored the effects of KRS and KGS in a transient focal stroke model.

METHODOLOGY/PRINCIPAL FINDINGS

Rats were subjected to middle cerebral artery occlusion for 2 hours followed by 22 h reperfusion. An equimolar dose of KRS or KGS was administered i.v. at the beginning of reperfusion. The results showed that KRS or KGS significantly attenuated the neurological deficits, brain infarct volume, and neuron and axon injury, reflected by the upregulation of neuronal nuclear antigen-positive neurons and downregulation of amyloid precursor protein immunoreactivity in the ipsilateral ischemic hemisphere. Moreover, KRS and KGS inhibited the expression of OX-42, glial fibrillary acidic protein, phosphorylated STAT3 and NF-κB p65, and the nuclear content of NF-κB p65. Subsequently, these flavonoids inhibited the expression of tumor necrosis factor α, interleukin 1β, intercellular adhesion molecule 1, matrix metallopeptidase 9, inducible nitric oxide synthase, and myeloperoxidase.

CONCLUSION/SIGNIFICANCE

Our findings suggest that postischemic treatment with KRS or KGS prevents ischemic brain injury and neuroinflammation by inhibition of STAT3 and NF-κB activation and has the therapeutic potential for the neuroinflammation-related diseases, such as ischemic stroke.

Microglial CD14 activated by iNOS contributes to neuroinflammation in cerebral ischemia

Stroke is one of the most frequent causes of death and disability worldwide. Cerebral ischemia is the major insult of stroke and induces acute inflammation by triggering excessive production of proinflammatory cytokines, leading to the exacerbation of primary brain damage. Toll-like receptor (TLR)- and nitric oxide-mediated signaling pathways have been identified under ischemic stress. However, the interaction between these two pathways in controlling proinflammatory cytokines has not been well addressed during cerebral ischemia. Adult male C57BL/6 mice were subjected to middle cerebral artery occlusion (MCAO) for stroke induction. The MCAO procedure resulted in a significant infarct in the brain after 24h. The infarcted side of the brain had marked elevation of TNF-α gene and protein expression, compared to the sham brain. The expression of CD14, a co-receptor of TLR4, was induced by MCAO, while the expression of TLR4 remained unchanged. The levels of inducible nitric oxide synthase (iNOS) and nitrotyrosine were also upregulated in the infracted side of the brain. Correspondingly, exposing murine microglial BV2 cells to hypoxia (1% O2) for 20h resulted in an increased expression of TNF-α, CD14, iNOS, and nitrotyrosine. When BV2 cells were treated with l-canavanine, an iNOS selective inhibitor, the elevation of TNF-α and CD14 induced by hypoxia was inhibited. This inhibition was associated with an increase of IκB. These results suggest that the upregulation of TNF-α production in ischemic stroke is partially through increasing iNOS, and then CD14 expression leading to the activation of the NF-κB pathway in microglia.

Sex, stroke, and inflammation: the potential for estrogen-mediated immunoprotection in stroke

Stroke is the third leading cause of death and the primary cause of disability in the developed world. Experimental and clinical data indicate that stroke is a sexually dimorphic disease, with males demonstrating an enhanced intrinsic sensitivity to ischemic damage throughout most of their lifespan. The neuroprotective role of estrogen in the female brain is well established, however, estrogen exposure can also be deleterious, especially in older women. The mechanisms for this remain unclear. Our current understanding is based on studies examining estrogen as it relates to neuronal injury, yet cerebral ischemia also induces a robust sterile inflammatory response involving local and systemic immune cells. Despite the potent anti-inflammatory effects of estrogen, few studies have investigated the contribution of estrogen to sex differences in the inflammatory response to stroke. This review examines the potential role for estrogen-mediated immunoprotection in ischemic injury.

Cerebroprotective potential of resveratrol through anti-oxidant and anti-inflammatory mechanisms in rats

Oxidative stress and inflammation are two important pathological mechanisms involved in cerebral ischemia and reperfusion injury. In pathological conditions such as cerebral infarction, the free radical production is greater than that of elimination by endogenous anti-oxidant system, by this undesirable effect brain is highly injured. Resveratrol is reported to have anti-oxidant and anti-inflammatory, athero-protective activities. Therefore, the aim of the present study is to evaluate the therapeutic potential of resveratrol against cerebral infarction induced by ischemia and reperfusion injury in Wistar rats. Bi-common carotid occlusion followed by 4 h reperfusion model was used to induce cerebral infarction. Percent infarction, oxidative stress markers (malondialdehyde, catalase, superoxide dismutase) and inflammatory markers (myeloperoxidase, TNF-α, IL-6, ICAM-1 and IL-10) were measured. TNF-α, IL-6, IL-10, and intracellular adhesive molecule-I (ICAM-1) levels were quantified by enzyme-linked immunosorbent assay (ELISA). Resveratrol produced significant dose-dependent reduction in percent cerebral infarct volume. At resveratrol 20 mg/kg dose, there was a significant reduction in oxidative stress and inflammatory markers like malondialdehyde, TNF-α, IL-6, myeloperoxidase and ICAM-I and in contrast there was a significant increase in anti-oxidants and anti-inflammatory markers like superoxide dismutase, catalase and IL-10 levels. Resveratrol showed significant cerebroprotective action mediated by anti-oxidant and anti-inflammatory mechanisms.

(1)H NMR-based metabolomics exploring biomarkers in rat cerebrospinal fluid after cerebral ischemia/reperfusion

In our study, metabolomics was used to investigate biochemical changes in the early stages of rats focal cerebral ischemia/reperfusion (I/R) injury. Cerebrospinal fluid (CSF) samples at 0, 0.5, 1, 3, and 6 h of reperfusion (n = 10), based on (1)H NMR spectroscopy and multivariate data analyses, were tested to analyze the changing of metabolites during the early disease process. Partial least squares-discriminant analysis scores plots of the (1)H NMR data revealed clear differences among the experiment groups. Combining the results of the loading plot and t-test, we found that twenty-seven metabolites were changed significantly (p < 0.05) in the CSF samples among the different groups. Among that, the potential biomarkers in CSF of ischemic rats were: acetic acid, 3-hydroxyisovaleric acid, 3-hydroxybutyric acid, choline, l-alanine, creatine, creatinine, glycine, pyruvic acid, glycerol, glutamic acid, d-fructose, l-lactic acid and acetone. These findings help us understand the biochemical metabolite changes in CSF of I/R rats in early stages. What's more, metabolomics may, therefore, have the potential to be developed into a clinically useful diagnostic tool of ischemic brain injury.

Isoflurane postconditioning reduces ischemia-induced nuclear factor-κB activation and interleukin 1β production to provide neuroprotection in rats and mice

Application of isoflurane, a volatile anesthetic, after brain ischemia can reduce ischemic brain injury in rodents (isoflurane postconditioning). This study is designed to determine whether isoflurane postconditioning improves long-term neurological outcome after focal brain ischemia and whether this protection is mediated by attenuating neuroinflammation. Adult male Sprague-Dawley rats were subjected to a 90-min middle cerebral arterial occlusion (MCAO). Isoflurane postconditioning was performed by exposing rats to 2% isoflurane for 60min immediately after the MCAO. Isoflurane postconditioning reduced brain infarct volumes, apoptotic cells in the ischemic penumbral brain tissues and neurological deficits of rats at 4weeks after the MCAO. Isoflurane postconditioning reduced brain ischemia/reperfusion-induced nuclear transcription factor (NF)-κB (NF-κB) activation as well as interleukin 1β (IL-1β) and interleukin-6 production in the ischemic penumbral brain tissues at 24h after the MCAO. IL-1β deficient mice had smaller brain infarct volumes and better neurological functions than wild-type mice at 24h after a 90-min focal brain ischemia. Isoflurane posttreatment failed to induce neuroprotection in the IL-1β deficient mice. Our results suggest that isoflurane postconditioning improved long-term neurological outcome after transient focal brain ischemia. This protection may be mediated by inhibiting NF-κB activation and the production of the proinflammatory cytokine IL-1β.

Functional role of soluble receptor for advanced glycation end products in stroke

OBJECTIVE

Little is known about the involvement of the soluble form of receptor for advanced glycation end products (sRAGE) in acute ischemic stroke (IS). Here, we aim to identify the role of plasma sRAGE and high mobility group box 1 (HMGB1) in imaging-confirmed IS patients, as well as mice subjected to focal ischemic stroke.

METHODS AND RESULTS

IS patients were recruited and plasma samples were collected for the measurement of sRAGE and HMGB1 after stroke. The relation of sRAGE and HMGB1 with acute IS was also investigated in a C57BL/6J mouse model of focal ischemic stroke and primary cortical neurons subjected to oxygen and glucose deprivation. Plasma levels of sRAGE and HMGB1 were both significantly increased within 48 hours after IS, and the sRAGE level was an independent predictor of functional outcome at 3 months poststroke. Immunoprecipitation assays revealed that the binding of plasma HMGB1 to sRAGE increased progressively after IS both in patients and mice. Administration of recombinant sRAGE significantly reduced infiltrating immune cells and improved the outcome of injury in mice, protected cultured neurons against oxygen and glucose deprivation-induced cell death, and ameliorated the detrimental effect of recombinant HMGB1.

CONCLUSIONS

Early poststroke plasma sRAGE may play a protective role in IS by capturing HMGB1. Hence, recombinant sRAGE is a potential therapeutic agent in acute IS.

The Effect of Pentoxifylline on bcl-2 Gene Expression Changes in Hippocampus after Ischemia-Reperfusion in Wistar Rats by a Quatitative RT-PCR Method

Ischemia-reperfusion injury is the tissue damage caused when blood supply returns to the tissue after a period of ischemia or lack of oxygen. Ischemia-reperfusion brain injury initiates an inflammatory response involving the expression of adhesion molecules and cytokines. Twenty-four male Wistar rats (250-300 g body wt) were used in this study. The animals were divided into four groups of 6 rats each: I: Control group that was subjected to ischemia-reperfusion, II: Ischemia-reperfusion group that was subjected to all surgical procedures, III: Drug group that received pentoxifylline (200, 400 and 600 mg/kg) 60 min before and after ischemia and IV: Vehicle group that received saline. Seventy two h after ischemia-reperfusion, the hippocampus was taken for studying the changes in bcl-2 gene expression. We used quantitative real-time PCR for the detection of bcl-2 gene expression in ischemia and drug groups and then compared them to normal samples. The results showed the gene dosage ratio of 0.66 and 1.5 for ischemia group and the drug groups, respectively. The results also showed the bcl-2 gene expression declined in ischemia group as compared to the drug group. Furthermore, we observed a significant difference in the bcl-2 gene expression between ischemia and drug groups. These findings are consistent with anti-apoptotic properties of bcl-2 gene. Furthermore this method provides a powerful tool for the investigators to study brain ischemia and respond to the treatment drugs with anti-apoptotic agents.

Inflammatory response following diffuse axonal injury

DAI is a leading cause of the patient's death or lasting vegetable state following severe TBI, and up to now the detailed mechanism of axonal injury after head trauma is still unclear. Inflammatory responses have been proved to be an important mechanism of neural injury after TBI. However, most of these studies are concerned with focal cerebral injury following head trauma. In contrast to focal injury, studies on the inflammatory reaction following DAI are only beginning. And in this article, we aimed to review such studies. From the studies reviewed, immune response cells would become reactive around the sites of axonal injury after DAI. Besides, the concentrations of several important inflammatory factors, such as IL-1 family, IL-6 and TNF-ɑ, increased after DAI as well, which implies the participation of inflammatory responses. It can be concluded that inflammatory responses probably participate in the neural injury in DAI, but at present the study of inflammatory responses following DAI is still limited and the clear effects of inflammatory response on axonal injury remain to be more explored.

Novel therapeutic strategies targeting innate immune responses and early inflammation after stroke

Post-ischemic inflammation is an essential step in the progression of ischemic stroke. This review focuses on the function of infiltrating immune cells, macrophages, and T cells, in ischemic brain injury. The brain is a sterile organ; however, the activation of Toll-like receptor (TLR) 2 and TLR4 is pivotal in the beginning of post-ischemic inflammation. Some endogenous TLR ligands are released from injured brain cells, including high mobility group box 1 and peroxiredoxin family proteins, and activate the infiltrating macrophages and induce the expression of inflammatory cytokines. Following this step, T cells also infiltrate into the ischemic brain and mediate post-ischemic inflammation in the delayed phase. Various cytokines from helper T cells and γδT cells function as neurotoxic (IL-23/IL-17, IFN-γ) or neuroprotective (IL-10, IL-4) mediators. Novel neuroprotective strategies should therefore be developed through more detailed understanding of this process and the regulation of post-ischemic inflammation.

ApolipoproteinE mimetic peptides improve outcome after focal ischemia

Growing clinical evidence implicates isoform-specific effects of apolipoprotein E (apoE) in reducing neuroinflammation and mediating adaptive responses following ischemic and traumatic brain injury. However, the intact apoE holoprotein does not cross the blood-brain barrier and thus has limited therapeutic potential. We have created a small peptide, COG1410 (acetyl-AS-Aib-LRKL-Aib-KRLL-amide), derived from the apoE receptor-binding region. COG1410 retains the anti-inflammatory and neuroprotective biological properties of the intact holoprotein and penetrates the blood-brain barrier. In the current study, we utilized a murine model of transient focal cerebral ischemia and reperfusion to demonstrate that intravenous (IV) administration of COG1410 reduces infarct volume and radiographic progression of infarct, and improves functional outcome as assessed by rotarod when delivered up to 4h after ischemia onset.

Association of CXCL1 promoter polymorphism with ischaemic stroke in Korean population

This is a pilot study analysing association of chemokine gene polymorphisms (CXCL1, rs3117604; CXCL2, rs3806792; CCL2, rs2857656 and rs3760396; CCL5, rs2107538) in Korean patients with ischemic stroke (IS) (n = 120) and age-matched controls (n = 267). The CXCL1 gene and particularly T allele of rs3117604 was associated with IS.

Cerebrospinal fluid and plasma cytokines after subarachnoid haemorrhage: CSF interleukin-6 may be an early marker of infection

BACKGROUND

Cytokines and cytokine receptor concentrations increase in plasma and cerebrospinal fluid (CSF) of patients following subarachnoid haemorrhage (SAH). The relationship between plasma and CSF cytokines, and factors affecting this, are not clear.

METHODS

To help define the relationship, paired plasma and cerebrospinal fluid (CSF) samples were collected from patients subject to ventriculostomy. Concentrations of key inflammatory cytokines, interleukin (IL)-1ß, IL-1 receptor antagonist (IL-1Ra), IL-1 receptor 2, IL-6, IL-8, IL-10, tumour necrosis factor (TNF)-α, and TNF receptors (TNF-R) 1 and 2 were determined by immunoassay of CSF and plasma from 21 patients, where samples were available at three or more time points.

RESULTS

Plasma concentrations of IL-1ß, IL-1Ra, IL-10, TNF-α and TNF-R1 were similar to those in CSF. Plasma TNF-R2 and IL-1R2 concentrations were higher than in CSF. Concentrations of IL-8 and IL-6 in CSF were approximately10 to 1,000-fold higher than in plasma. There was a weak correlation between CSF and plasma IL-8 concentrations (r = 0.26), but no correlation for IL-6. Differences between the central and peripheral pattern of IL-6 were associated with episodes of ventriculostomy-related infection (VRI). A VRI was associated with CSF IL-6 >10,000 pg/mL (P = 0.0002), although peripheral infection was not significantly associated with plasma IL-6.

CONCLUSIONS

These data suggest that plasma cytokine concentrations cannot be used to identify relative changes in the CSF, but that measurement of CSF IL-6 could provide a useful marker of VRI.

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.