Brain Infarct Volume Research Articles

Intranasal administration of β-1, 3-galactosyltransferase 2 confers neuroprotection against ischemic stroke by likely inhibiting oxidative stress and NLRP3 inflammasome activation.

Ischemic stroke is one of the major causes of morbidity and mortality. The β-1, 3-galactosyltransferase 2 (B3galt2), a member of β-1, 3-galactosyltransferase family, is playing a vital role in the pathological process of cerebral ischemic injury, but its underlying mechanisms remain unclear. In the present study, we examined the involvement of oxidative stress and NLRP3 inflammasome activation in the neuroprotective effect of B3galt2. Cerebral ischemia/reperfusion (I/R) injury was simulated in a mouse middle cerebral artery occlusion (MCAO) model. Recombinant human B3galt2 (rh-B3galt2) was administered intranasally 1h post MCAO, and TGF-β1-siRNA was administered intracerebroventricularly 24 h before MCAO. Outcome measures included brain infarct volume, neurological function, blood-brain barrier (BBB) permeability, neuronal apoptosis, oxidative stress, and the inflammatory response. First, we found that rh-B3galt2 significantly alleviated brain infarct volume and BBB permeability, improved neurological function, and attenuated I/R-induced neuron apoptosis and oxidative stress. Furthermore, rh-B3galt2 attenuated pro-inflammatory cytokines, NF-κB, IL-6, TNF-α, and IL-1β, and inhibited NLRP3 inflammasome activation. Finally, inhibition of TGF-β1 by TGF-β1-siRNA abolished the anti-oxidative and anti-inflammatory effects of rh-B3galt2 in mice after I/R. Collectively, our study demonstrated that rh-B3galt2 exerts neuroprotective effects by regulating cerebral ischemia-induced oxidative stress and NLRP3 inflammasome, which is mainly dependent on the heightening of the TGF-β1 pathway. Thus, B3galt2 might be considered a new therapeutic target for ischemic stroke treatment.

Dihydromyricetin Attenuates Cerebral Ischemia Reperfusion Injury by Inhibiting SPHK1/mTOR Signaling and Targeting Ferroptosis.

BackgroundDihydromyricetin (DHM) exerts protective effects in various brain diseases. The aim of this research was to investigate the biological role of DHM in cerebral ischemia reperfusion (I/R) injury.MethodsWe generated a rat model of cerebral I/R injury by performing middle cerebral artery occlusion/reperfusion (MCAO/R). The neurological score and brain water content of the experimental rats was then evaluated. The infarct volume and extent of apoptosis in brain tissues was then assessed by 2,3,5-triphenyltetrazolium (TTC) and TdT-mediated dUTP nick end labeling (TUNEL) staining. Hippocampal neuronal cells (HT22) were subjected to oxygen-glucose deprivation/reperfusion (OGD/R) and cell counting kit-8 (CCK-8) assays and flow cytometry were performed to detect cell viability and apoptosis. The levels of lipid reactive oxygen species (ROS) and iron were detected and the expression levels of key proteins were assessed by Western blotting.ResultsDHM obviously reduced neurological deficits, brain water content, infarct volume and cell apoptosis in the brain tissues of MCAO/R rats. DHM repressed ferroptosis and inhibited the sphingosine kinase 1 (SPHK1)/mammalian target of rapamycin (mTOR) pathway in MCAO/R rats. In addition, DHM promoted cell viability and repressed apoptosis in OGD/R-treated HT22 cells. DHM also suppressed the levels of lipid ROS and intracellular iron in OGD/R-treated HT22 cells. The expression levels of glutathione peroxidase 4 (GPX4) was enhanced while the levels of acyl-CoA synthetase long-chain family member 4 (ACSL4) and phosphatidylethanolamine binding protein 1 (PEBP1) were reduced in OGD/R-treated HT22 cells in the presence of DHM. Moreover, the influence conferred by DHM was abrogated by the overexpression of SPHK1 or treatment with MHY1485 (an activator of mTOR).ConclusionThis research demonstrated that DHM repressed ferroptosis by inhibiting the SPHK1/mTOR signaling pathway, thereby alleviating cerebral I/R injury. Our findings suggest that DHM may be a candidate drug for cerebral I/R injury treatment.

Ruta graveolens water extract (RGWE) ameliorates ischemic damage and improves neurological deficits in a rat model of transient focal brain ischemia

Introduction and aimsThe limited therapeutic options for ischemic stroke treatment render necessary the identification of new strategies. In recent years, it has been shown that natural compounds may represent a valid therapeutic opportunity. Therefore, the present study aimed to evaluate the protective effect of Ruta graveolens water extract (RGWE) in an in vivo experimental model of brain ischemia. MethodsRGWE effects on ischemic damage and neurological function were evaluated in adult rats subjected to transient occlusion of the Middle Cerebral Artery (tMCAO), receiving two intraperitoneal injections of RGWE, 100 and 300 min after the induction of ischemia. In addition, astroglial and microglial activation was measured as GFAP and IBA-1 expression by immunofluorescence and confocal microscopy analysis. ResultsTreatment with RGWE containing 10 mg/kg of Rutin, the major component, ameliorates the ischemic damage and improves neurological performances. Interestingly, the pro-inflammatory states of astrocytes and microglia, respectively detected by using C3 and iNOS markers, were significantly reduced in ipsilateral cortical and striatal areas in ischemic RGWE-treated rats. ConclusionsRGWE shows a neuroprotective effect on brain infarct volume extent in a transient focal cerebral ischemia model and this effect was paralleled by the prevention of pro-inflammatory astroglial and microglial activation. Collectively, our findings support the idea that natural compounds may represent potential therapeutic opportunities against ischemic stroke.

MicroRNA-29b Suppresses Inflammation and Protects Blood-Brain Barrier Integrity in Ischemic Stroke.

Objectives Following cerebral ischemia, microRNA- (miR-) 29b in circulating blood is downregulated. This study investigates the underlying mechanism and implications of miR-29b in leukocyte induction. Methods miR-29b from stroke patients and rats with middle cerebral artery occlusion (MCAO) were assessed using real-time polymerase chain reaction (PCR). miR-29b agomir was used to increase miR-29b expression in leukocytes via intravenous injection. C1q and tumor necrosis factor (C1QTNF) 6, interleukin- (IL-) 1β, zonula occludens- (ZO-) 1, occludin, and ischemic outcomes were assessed in MCAO rats. Additionally, hCMEC/D3 cells were subjected to oxygen–glucose deprivation (OGD) and cocultured with HL-60 cells. Results miR-29b levels in neutrophils were found to be significantly lower in stroke patients compared with healthy controls, which may indicate its high diagnostic sensitivity and specificity for stroke. Moreover, miR-29b levels in leukocytes showed a negative correlation with National Institute of Health Stroke Scale (NIHSS) scores and C1QTNF6 levels. In MCAO rats, miR-29b overexpression reduced brain infarct volume and brain edema, decreasing IL-1β levels in leukocytes and in the brain 24 hours poststroke. miR-29b attenuated IL-1β expression via C1QTNF6 inhibition, leading to decreased blood-brain barrier (BBB) disruption and leukocyte infiltration. Moreover, miR-29b overexpression in HL-60 cells downregulated OGD-induced hCMEC/D3 cell apoptosis and increased ZO-1 and occludin levels in vitro. Conclusion Leukocytic miR-29b attenuates inflammatory response by augmenting BBB integrity through C1QTNF6, suggesting a novel miR-29b-based therapeutic therapy for ischemic stroke.

Neuroprotective Effects of an Edible Pigment Brilliant Blue FCF against Behavioral Abnormity in MCAO Rats.

Ischemic stroke leads to hypoxia-induced neuronal death and behavioral abnormity, and is a major cause of death in the modern society. However, the treatments of this disease are limited. Brilliant Blue FCF (BBF) is an edible pigment used in the food industry that with multiple aromatic rings and sulfonic acid groups in its structure. BBF and its derivatives were proved to cross the blood-brain barrier and have advantages on the therapy of neuropsychiatric diseases. In this study, BBF, but not its derivatives, significantly ameliorated chemical hypoxia-induced cell death in HT22 hippocampal neuronal cell line. Moreover, protective effects of BBF were attributed to the inhibition of the extracellular regulated protein kinase (ERK) and glycogen synthase kinase-3β (GSK3β) pathways as evidenced by Western blotting analysis and specific inhibitors. Furthermore, BBF significantly reduced neurological and behavioral abnormity, and decreased brain infarct volume and cerebral edema induced by middle cerebral artery occlusion/reperfusion (MCAO) in rats. MCAO-induced increase of p-ERK in ischemic penumbra was reduced by BBF in rats. These results suggested that BBF prevented chemical hypoxia-induced otoxicity and MCAO-induced behavioral abnormity via the inhibition of the ERK and GSK3β pathways, indicating the potential use of BBF for treating ischemic stroke

Dl-3-n-Butylphthalide Reduced Neuroinflammation by Inhibiting Inflammasome in Microglia in Mice after Middle Cerebral Artery Occlusion.

The inflammatory response is one of the key events in cerebral ischemia, causing secondary brain injury and neuronal death. Studies have shown that the NLRP3 inflammasome is a key factor in initiating the inflammatory response and that Dl-3-n-butylphthalide (NBP) can attenuate the inflammatory response and improve neuronal repair during ischemic stroke. However, whether NBP attenuates the inflammatory response via inhibition of NLRP3 remains unclear. A 90 min middle cerebral artery occlusion was induced in 62 2-month-old adult male ICR mice, and NBP was administered by gavage zero, one, or two days after ischemia. Brain infarct volume, neurological deficits, NLRP3, microglia, and neuronal death were examined in sacrificed mice to explore the correction between NBP effects and NLRP3 expression. NBP significantly reduced infarct volume and attenuated neurological deficits after ischemic stroke compared to controls (p < 0.05). Moreover, it inhibited ASC+ microglia activation and NLRP3 and CASP1 expression in ischemic mice. In addition, neuronal apoptosis was reduced in NBP-treated microglia cultures (p < 0.05). Our results indicate that NBP attenuates the inflammatory response in ischemic mouse brains, suggesting that NBP protects against microglia activation via the NLRP3 inflammasome.

Treatment with IgM-enriched intravenous immunoglobulins enhances clearance of stroke-associated bacterial lung infection.

Post-stroke infection is a common complication of stroke that is associated with poor outcome. We previously reported that stroke induces an ablation of multiple sub-populations of B cells and reduces levels of immunoglobulin M (IgM) antibody, which coincides with the development of spontaneous bacterial pneumonia. The loss of IgM after stroke could be an important determinant of infection susceptibility and highlights this pathway as a target for intervention. We treated mice with a replacement dose of IgM-enriched intravenous immunoglobulin (IgM-IVIg) prior to and 24 h after middle cerebral artery occlusion (MCAO) and allowed them to recover for 2- or 5-day post-surgery. Treatment with IgM-IVIg enhanced bacterial clearance from the lung after MCAO and improved lung pathology but did not impact brain infarct volume. IgM-IVIg treatment induced immunomodulatory effects systemically, including rescue of splenic plasma B cell numbers and endogenous mouse IgM and IgA circulating immunoglobulin concentrations that were reduced by MCAO. Treatment attenuated MCAO-induced elevation of selected pro-inflammatory cytokines in the lung. IgM-IVIg treatment did not increase the number of lung mononuclear phagocytes or directly modulate macrophage phagocytic capacity but enhanced phagocytosis of Staphylococcus aureus bioparticles in vitro. Low-dose IgM-IVIg contributes to increased clearance of spontaneous lung bacteria after MCAO likely via increasing availability of antibody in the lung to enhance opsonophagocytic activity. Immunomodulatory effects of IgM-IVIg treatment may also contribute to reduced levels of damage in the lung after MCAO. IgM-IVIg shows promise as an antibacterial and immunomodulatory agent to use in the treatment of post-stroke infection.

Decitabine attenuates ischemic stroke by reducing astrocytes proliferation in rats.

DNA methylation regulates epigenetic gene expression in ischemic stroke. Decitabine attenuates ischemic stroke by inhibiting DNA methylation. However, the underlying mechanism of this effect is not known. A model of ischemic stroke in Sprague-Dawley rats was induced through middle cerebral artery occlusion followed by reperfusion step. The rats were randomly treated with decitabine or vehicle by a one-time intraperitoneal injection. Sham rats received similar treatments. Four days after treatment, the rats were perfused with saline or 4% paraformaldehyde after which the brain was excised. DNA methylation level and brain infarct volume were determined by dot blot and histochemistry, respectively. The cellular co-localization and quantitative analysis of DNA methylation were assessed by immunohistochemistry and expression levels of cdkn1b (p27) mRNA and protein were measured by qRT-PCR and immunohistochemistry, respectively. The proliferation of astrocytes and number of neurons were determined by immunohistochemistry. Rats treated with decitabine showed hypomethylation and reduced infarct volume in the cortex. DNA methylation was decreased in astrocytes. Decitabine upregulated p27 mRNA and protein expression levels and attenuated the proliferation of astrocytes in vivo and vitro. Decitabine promotes p27 gene expression possibly by inhibiting its DNA methylation, thereby decreases the proliferation of astrocytes, neuronal death and infarct volume after ischemic stroke.

Rs2253820 Variant Controls Blood Pressure Dip After Stroke by Increasing CLOCK-BMAL1 Expression.

Circadian rhythm (CR) disturbances are associated with the development of cardiovascular diseases, including stroke. The central clock in the brain, which is maintained by circadian genes, maintains the daily rhythm according to the external environment. Here, we aimed to probe the interaction between the PER1rs2253820 variant and blood pressure dip (BPD) status and mechanisms. We studied spontaneously hypertensive rats (SHR) with transient middle cerebral artery occlusion (SHR-tMCAO). The mutation site of PER1 was identified using bioinformatics analysis, followed by RT-qPCR and western blot validation. SHR-tMCAO showed increased brain infarct volume associated with CR. CK1, BMAL1, and CLOCK proteins oscillated synchronously in SHR-tMCAO, whereas PER1 showed rhythm disturbances. CK1, CLOCK, and BMAL1 levels first elevated and then slowly decreased after ischemia, whereas PER1 level continued to decrease. CLOCK and PER1 are co-localized in the suprachiasmatic nucleus of the hypothalamus. rs2253820 accelerates PER1 phosphorylation via CK1. The rs2253820 knockdown attenuated CR disturbances, reduced PER1 phosphorylation in SHR and inhibited the transcription of BMAL1 and CLOCK. CK1 suppression attenuated the degradation of PER1 phosphorylation and reduced neuronal damage. Overall, rs2253820 accelerated PER1v phosphorylation via CK1, leading to PER1 degradation, BMAL1 and CLOCK1 transcription, and BPD exacerbation.

Calenduloside E alleviates cerebral ischemia/reperfusion injury by preserving mitochondrial function

Calenduloside E (CE) isolated from Aralia elata (Miq.) Seem. is a natural triterpenoid saponin that can reportedly ameliorate myocardial ischemia/reperfusion injury. However, its potential roles and mechanism in cerebral ischemia/reperfusion injury are barely understood. In this study, we established an oxygen-glucose deprivation/reoxygenation (OGD/R) model in HT22 cells. We found that CE significantly attenuated the OGD/R-induced inhibition of cell viability and apoptotic cell death in HT22 cells. Moreover, CE treatment significantly ameliorated OGD/R-induced mitochondrial fission by inhibiting mitochondrial dynamin-related protein 1 (Drp1) recruitment and increasing Drp1 phosphorylation at Ser637. CE treatment significantly ameliorated OGD/R-induced mitochondrial dysfunction by increasing the mitochondrial membrane potential and reducing the mitochondrial ROS and cellular calcium accumulation. Moreover, CE treatment significantly inhibited the OGD/R-induced release of mitochondrial Cytochrome C and increase in Bax, Cleaved-caspase3 and Cleaved-caspase9 protein levels, whereas CE treatment significantly reversed the OGD/R-induced decrease in Bcl-2 and full length of caspase3 and caspase9 protein levels. In vivo, we found that CE treatment significantly ameliorated ischemic/hypoxic-induced brain infarct volume, neurological deficits, and neuronal apoptosis in mice after middle cerebral artery occlusion and reperfusion. CE treatment also significantly ameliorated the mitochondrial transmembrane potential, decreased Cytochrome C release, and reversed the increase in Bax, Cleaved-caspase3 and Cleaved-caspase9 protein levels and the decrease in Bcl-2 and full length of caspase3 and caspase9 protein levels induced by cerebral ischemia/reperfusion (I/R). All these results indicated that CE treatment exerted a neuroprotective effect by ameliorating mitochondrial dysfunction during cerebral I/R injury.

Echinacoside Alleviates Cognitive Impairment in Cerebral Ischemia Rats through α 7nAChR-Induced Autophagy.

To evaluate the effect of echinacoside (ECH) on cognitive dysfunction in post cerebral stroke model rats. The post stroke cognitive impairment rat model was created by occlusion of the transient middle cerebral artery (MCAO). The rats were randomly divided into 3 groups by a random number table: the sham group (sham operation), the MCAO group (received operation for focal cerebral ischemia), and the ECH group (received operation for focal cerebral ischemia and ECH 50 mg/kg per day), with 6 rats in each group. The infarct volume and spatial learning were evaluated by triphenyl tetrazolium chloride staining and Morris water maze. The expression of α7nAChR in the hippocampus was detected by immunohistochemistry. The contents of acetylcholine (ACh), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), activities of choline acetyltransferase (ChAT), acetylcholinesterase (AChE), and catalase (CAT) were evaluated by enzyme linked immunosorbent assay. The neural apoptosis and autophagy were determined by TUNEL staining and LC3 staining, respectively. ECH significantly lessened the brain infarct volume and ameliorated neurological deficit in infarct volume and water content (both P<0.01). Compared with MCAO rats, administration of ECH revealed shorter escape latency and long retention time at 7, 14 and 28 days (all P<0.01), increased the α7nAChR protein expression, ACh content, and ChAT activity, and decreased AChE activity in MCAO rats (all P<0.01). ECH significantly decreased MDA content and increased the GSH content, SOD, and CAT activities compared with MCAO rats (all P<0.05). ECH suppressed neuronal apoptosis by reducing TUNEL-positive cells and also enhanced autophagy in MCAO rats (all P<0.01). ECH treatment helped improve cognitive impairment by attenuating neurological damage and enhancing autophagy in MCAO rats.

Evaluation of extracranial carotid flow velocities in patients presenting with acute ischemic stroke: A clinical study conducted in Turkey

Objective. The mechanism underlying the relationship between carotid flow velocities and stroke events remains unclear. This study aimed to reveal the relationship of flow velocity measurements with risk factors in patients with acute ischemic stroke. Material and methods. A group of patients between the ages of 41-90 who applied to Mengücek Training and Research Hospital in the Eastern Anatolia Region of Turkey between 2014-2015 due to acute ischemic stroke were included. Groups with large artery atherosclerosis and small-vessel occlusion according to the Toast classification were included in the study. Brain tomography and magnetic resonance imaging, echocardiography, high-resolution color Doppler Ultrasonography examinations were performed. Internal carotid artery peak-systolic and end-diastolic flow velocity, common carotid artery peak-systolic and end-diastolic flow velocity, internal carotid artery peak systolic-common carotid artery peak-systolic velocity ratio and common carotid artery intima-media thickness were measured with Doppler Ultrasonography. The relationship between carotid flow velocities and brain infarction volume, comorbid factors, biochemical variables, left ventricular systolic-diastolic dysfunction was defined by using Statistical Package for Social Sciences version 21.0. Outcomes. In acute ischemic stroke groups, a significant negative correlation between common carotid artery end-diastolic flow velocity and brain infarction volume, a significant positive relationship between common carotid artery peak-systolic velocity and smoking, a significant positive correlation between common carotid artery intima-media thickness and blood glucose and hba1c, a significant negative correlation between common carotid artery end-diastolic flow velocity and hypertension, a significant relationship between common carotid artery end-diastolic flow velocity and ischemic heart disease, an increase in cerebral infarction in patients with left ventricular systolic dysfunction and a decrease in Internal carotid artery peak-systolic flow velocity in patients with left ventricular diastolic dysfunction were detected. Conclusions. In clinical practice, Doppler ultrasound is currently the main diagnostic tool for evaluating the diagnosis of carotid stenosis. In stenosis in the carotid artery system, it should be known as a basic rule that the flow velocity in the stenosis area increases, except for in severe stenosis and four basic measurements should be made to determine the degree of stenosis clearly. These measurements are peak systolic flow velocity (PSV), end-diastolic flow velocity (EDV), peak-systolic flow velocity ratio (ICA/CCA PSV). The purpose of sonographic evaluation of the extracranial cerebral arteries is to prevent bad sequelae and permanent deficits together with cerebral infarction.

Metformin protects against pericyte apoptosis and promotes neurogenesis through suppressing JNK p38 MAPK signalling activation in ischemia/reperfusion injury

Metformin (MET) has been the subject of many classic studies in possessing antiapoptotic, anti-inflammatory, antioxidation activities and antiviral. Recently investigators have examined the anti-apoptosis effects of MET in acute myocardial infarction and Intracerebral hemorrhage, but very little is currently known about how it regulates ischemic stroke-induced pericytes apoptosis and neural stem cells (NSCs) proliferation. The present research explored the potential neuroprotective mechanisms of MET using transient middle cerebral artery occlusion(tMCAO) mice. The experimental work presented that tMCAO mice treated by metformin had better neurologic outcomes on days 1, 3, and 7 after operation, and alleviated blood–brain barrier (BBB) destruction, brain water content and infarct volume on 72 h after surgery. The data showed that MET alleviated BBB disruption by reducing PDGFRβ/ matrix metalloproteinase-9 (MMP9) positive cells, relieving zonula occludens-1 (ZO-1) drop away and increasing pericyte coverage through remarkably reducing the percentage of PDGFRβ/caspase-3 positive cells. In addition, MET induced antiapoptotic activity followed by downregulating cleaved caspase-3 and Bax expression. Moreover, JNK signaling pathway has been proved to be pivotal in mediating apoptosis in cerebral ischemia/reperfusion (I/R) injury. The results of this research illustrated that MET treatment downregulated the levels of phosphorylated JNK and P38 in vivo, however the use of JNK activator anisomycin (ANI) could reverse the neuroprotection effect of MET, demonstrating that the JNK pathway is associated with the anti-apoptosis mechanisms of MET. Finally, metformin remarkably increased the percentage of BrdU/DCX-positive cells in subventricular zone (SVZ) and up-regulated BDNF、VEGF and NGF expression after ischemia/reperfusion(I/R) injury on day 7. Our data illustrated that metformin provides an effective therapy for I/R injury.

Modified Citrus Pectin Alleviates Cerebral Ischemia/Reperfusion Injury by Inhibiting NLRP3 Inflammasome Activation via TLR4/NF-ĸB Signaling Pathway in Microglia.

BackgroundGalectin-3 acts as a mediator of microglial inflammatory response following stroke injury. However, it remains unclear whether inhibiting galectin-3 protects against cerebral ischemia/reperfusion injury. We aimed to investigate the neuroprotective effects of modified citrus pectin (MCP, a galectin-3 blocker) in ischemic stroke and underlying mechanisms.MethodsThe middle cerebral artery occlusion/reperfusion (MCAO/R) model in C57BL/6J mice and oxygen-glucose deprivation/reoxygenation (ODG/R) model in neuronal (HT-22) and microglial (BV-2) cells were utilized in the following experiments: 1) the neuroprotective effects of MCP with different concentrations were evaluated in vivo and in vitro through measuring neurological deficit scores, brain water content, infarction volume, cell viability, and cell apoptosis; 2) the mechanisms of its neuroprotection were explored in mice and microglial cells through detecting the expression of NLRP3 (NOD-like receptor 3) inflammasome-related proteins by immunofluorescence staining and Western blotting analyses.ResultsAmong the tested concentrations, 800 mg/kg/d MCP in mice and 4 g/L MCP in cells, respectively, showed in vivo and in vitro neuroprotective effects on all the tests, compared with vehicle group. First, MCP significantly reduced neurological deficit scores, brain water content and infarction volume, and alleviated cell injury in the cerebral cortex of MCAO/R model. Second, MCP increased cell viability and reduced cell apoptosis in the neuronal OGD/R model. Third, MCP blocked galectin-3 and decreased the expression of TLR4 (Toll-like receptor 4)/NF-κBp65 (nuclear factor kappa-B)/NLRP3/cleaved-caspase-1/IL-1β (interleukin-1β) in microglial cells.ConclusionThis is the first report that MCP exerts neuroprotective effects in ischemic stroke through blocking galectin-3, which may be mediated by inhibiting the activation of NLRP3 inflammasome via TLR4/NF-κB signaling pathway in microglia.

N-Methyl-D-Aspartate Receptors Antagonist Prevents Secondary Ischemic Brain Injury Associated With Lipopolysaccharide-Induced Sepsis-Like State Presumably via Immunomodulatory Actions.

Infection is a major reason for poor stroke outcomes, and sepsis is a major cause of stroke-elated deaths. We herein examined whether NMDA receptor blockade, which was reported to exert anti-inflammatory actions, protects against the deleterious consequences of lipopolysaccharide (LPS)-induced sepsis-like state in adult male NMRI mice exposed to transient intraluminal middle cerebral artery occlusion (MCAO). At 24 h post-ischemia, vehicle or Escherichia coli LPS (2 or 4 mg/kg) was intraperitoneally administered, whereas 30 min later vehicle or ketamine (10 mg/kg), which is a non-competitive NMDA receptor antagonist, was intraperitoneally applied. Delivery of LPS at a dosage of 4 mg/kg induced a sepsis-like state characterized by a rectal temperature reduction by ∼4.0°C, increased neurological deficits in Clark score, cylinder and open-field tests, increased brain infarct volume and reduced neuronal survival in the previously ischemic tissue. Notably, additional treatment with ketamine (10 mg/kg) significantly attenuated the sepsis-associated rectal temperature reduction by ∼1.5°C, reduced neurological deficits, reduced infarct volume, and promoted neuronal survival. Ketamine alone did not influence infarct volume or neurological deficits. Real-time PCR data analysis showed that GFAP, CD86, CD206, IL-1β, and IL-10 mRNA levels were significantly increased in ischemic brains of LPS-treated compared with vehicle-treated mice. Additional treatment with ketamine significantly decreased IL-1β and IL-10, but not GFAP, CD86, and CD206 mRNA levels. Our data show that ketamine at a dose that on its own does not confer neuroprotection reverses the adverse effects of LPS-induced sepsis-like state post-ischemia, presumably via immunomodulatory actions.

Interleukin 13 promotes long-term recovery after ischemic stroke by inhibiting the activation of STAT3

BackgroundMicroglia/macrophages are activated after cerebral ischemic stroke and can contribute to either brain injury or recovery by polarizing microglia/macrophage into distinctive functional phenotypes with pro- or anti-inflammatory properties. Interleukin-13 (IL-13) is an anti-inflammatory cytokine that regulates microglia/macrophage polarization toward an anti-inflammatory phenotype. However, it is not clear whether IL-13 is beneficial after ischemic stroke long-term and the underlying molecular mechanism(s) remain unknown. Thus, we examined the effect of IL-13 on long-term recovery and microglia/macrophage polarization in mice with transient middle cerebral artery occlusion model (tMCAO).MethodstMCAO was induced in adult male C57BL/6J mice. IL-13 (60 μg/kg) was administered intranasally starting 2 h after stroke and continued for seven consecutive days. Sensorimotor function, spatial learning and memory function, as well as brain infarct volume were assessed up to 35 days after stroke. White matter integrity was evaluated by electrophysiology, immunofluorescence staining, and transmission electron microscopy. Microglia/macrophage activation was assessed using immunofluorescence staining and quantitative real-time polymerase chain reaction. Changes in immune cells in the brain and the periphery, and expression of IL-13 receptors in different brain cells were detected by flow cytometry. Primary neuron/microglia co-cultures and a STAT3 inhibitor were used for mechanistic studies.ResultsPost-treatment with IL-13 improved long-term neurofunctional recovery and decreased brain tissue atrophy after stroke. Intranasal delivery of IL-13 enhanced the structural and functional integrity of white matter after stroke. Furthermore, the neuroprotection afforded by IL-13 administration was not due to a direct effect on neurons, but by indirectly regulating the anti-inflammatory phenotype of microglia/macrophages. IL-13 treatment also had no effect on peripheral immune cells. Mechanistically, IL-13 improved the long-term outcome after ischemic stroke by promoting the polarization of microglia/macrophages toward the anti-inflammatory phenotype at least partially by inhibiting the phosphorylation of STAT3.ConclusionsIL-13 promotes white matter repair and improves neurofunctional outcomes after ischemic stroke by modulating microglia/macrophages via inhibition of STAT3 phosphorylation.

Pre‐ and post‐conditioning with poly I:C exerts neuroprotective effect against cerebral ischemia injury in animal models: A systematic review and meta‐analysis

BackgroundToll‐like receptor (TLR) agonist polyinosinic–polycytidylic acid (poly I:C) exerts neuroprotective effects against cerebral ischemia (CI), but concrete evidence supporting its exact mechanism of action is unclear.MethodsWe evaluated the neuroprotective role of poly I:C by assessing CI indicators such as brain infarct volume (BIV), neurological deficit score (N.S.), and signaling pathway proteins. Moreover, we performed a narrative review to illustrate the mechanism of action of TLRs and their role in CI. Our search identified 164 articles and 10 met the inclusion criterion.ResultsPoly I:C reduces BIV and N.S. (p = 0.00 and p = 0.03). Interestingly, both pre‐ and post‐conditioning decrease BIV (preC p = 0.04 and postC p = 0.00) and N.S. (preC p = 0.03 and postC p = 0.00). Furthermore, poly I:C upregulates TLR3 [SMD = 0.64; CIs (0.56, 0.72); p = 0.00], downregulates nuclear factor‐κB (NF‐κB) [SMD = −1.78; CIs (−2.67, −0.88); p = 0.0)], and tumor necrosis factor alpha (TNF‐α) [SMD = −16.83; CIs (−22.63, −11.02); p = 0.00].ConclusionWe showed that poly I:C is neuroprotective and acts via the TLR3/NF‐κB/TNF‐α pathway. Our review indicated that suppressing TLR 2/4 may illicit neuroprotection against CI. Further research on simultaneous activation of TLR3 with poly I:C and suppression of TLR 2/4 might open new vistas for the development of therapeutics against CI.

The mimetic of the brain neurotrophic factor GSB-106 has neuroprotective and neuroregenerative effects in experimental ischemic stroke

Background. A dimeric dipeptide mimetic of the brain-derived neurotrophic factor loop 4, bis(N-monosuccinyl-L-seryl-L-lysine) hexamethylenediamide (GSB-106), which activates TrkB, PI3K/AKT, MAPK/ERK and PLC-γ1 was created at the V. V. Zakusov Research Institute of Pharmacology. GSB-106 showed neuroprotective activity in vitro and in vivo at systemic administration. Objective. In the present study, we studied the effect of GSB-106 on the brain infarct volume, as well as on neurogenesis and synaptogenesis under conditions of experimental ischemic stroke induced by transient occlusion of the middle cerebral artery in rats, when it was first administered 24 h after ischemia onset. Methods. Dipeptide GSB-106 was administered i.p. in a dose of 0.1 mg/kg 24 h after surgery and then once a day, with the end of administration on theday 6 after surgery. On the day 7 brain samples were collected for morphometric and biochemical (Western-blot) analysis. Results. It was established that GSB-106 reduced the brain damage volume by 24%, restores impaired neurogenesis and/or gliogenesis (by Ki-67) in the hippocampus and in the striatum and completely restored the reduced immunoreactivity to synaptic markers synaptophysin and PSD-95 in the striatum. Conclusions. Thus, the dimeric dipeptide BDNF mimetic GSB-106 exhibits neuroregenerative properties at clinically relevant time window (24 h) in a model of ischemic stroke presumably due to stimulation of neurogenesis (and / or gliogenesis) and synaptogenesis.

Neuroprotective effect of 3,3'-diindolylmethane and ɑ-naphthoflavone, aryl hydrocarbon receptor modulators in an experimental model of ischemic stroke.

The aryl hydrocarbon receptor (AhR) mediated signaling pathway is being emerged as a current target for neuromodulation. The present study was conducted to characterize the neuroprotective action of AhR modulators, i.e., 3,3'-diindolylmethane (DIM) and ɑ-naphthoflavone (ANF) in an experimental model of stroke using transient middle cerebral artery occlusion (MCAO) in Wistar rats. The animals were treated with respective AhR modulators via intraperitoneal (i.p) injection 3 hrs after MCAO for 4 days (at 24 h interval). Following transient MCAO, the brain infarct volume, ND scoring, and various neuro behavioural tests were conducted to confirm the ischemic stroke. Further, oxidative stress parameters, inflammatory cytokines, and apoptotic mRNA expression were assessed. The histopathological changes in the brain of the rats were assessed using H&E staining and the results obtained were correlated with the molecular parameters. Treatment with AhR modulators had significantly decreased the brain infarct volume, ND scoring and improved neuro-behivoral deficits in animals following MCAO. A significant decrease was also observed in the oxidative stress, pro-inflammatory cytokines, and apoptotic mRNA expression in the AhR ligand treated groups. Moreover, a significant improvement was observed in the neuronal damage following MCAO in the treatment groups. AhR pathway modulation may be taken as a valuable therapeutic target for treating acute ischemic stroke (AIS).

Naoluo Xintong Decoction Ameliorates Cerebral Ischemia-Reperfusion Injury by Promoting Angiogenesis through Activating the HIF-1α/VEGF Signaling Pathway in Rats.

Background Naoluo Xintong decoction (NLXTD) is a traditional Chinese medicine (TCM) formula which has been used to improve neuronal functional recovery after cerebral ischemic stroke. However, the molecular mechanism underlying NLXTD's amelioration of ischemic stroke remains unclear. The present study was designed to explore the effect and mechanism of NLXTD on brain angiogenesis in a rat model with cerebral ischemia-reperfusion (I/R) injury targeting the hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) pathway. Materials and Methods Cerebral I/R model was established by the classical middle cerebral artery occlusion (MCAO) method. Sprague-Dawley (SD) male rats (n = 80) were randomly divided into the sham-operation group, the model group, the HIF-1α inhibitor 2-methoxyestradiol (2ME2) group, the 2ME2 with NLXTD group, and the NLXTD group. Neurological deficit test, TTC staining, H&E staining, TUNEL staining, immunohistochemistry (IH), immunofluorescence (IF), western blot, and quantitative RT-PCR were performed to evaluate the effect of NLXTD after MCAO. Results Administration of NLXTD significantly decreased neuron deficiency scores, reduced brain infarct volume, and lowered damaged and apoptotic cells after brain I/R injury in rats. Meanwhile, NLXTD had a protective effect on angiogenesis by increasing the MVD and the expressions of BrdU and CD34, which enhanced the number of endothelial cells in the ischemic penumbra brain. NLXTD treatment significantly raised the protein and mRNA levels of HIF-1α, VEGF, VEGFR2, and Notch1 compared with the model treatment. In contrast, a specific HIF-1α inhibitor, 2ME2, inhibited the improvement of neurological function and angiogenesis in NLXTD-induced rats with cerebral I/R injury, suggesting that NLXTD played a positive role in ischemic brain injury by activating the HIF-1α/VEGF signaling pathway. Conclusions NLXTD exerts neuroprotection targeting angiogenesis by upregulating the HIF-1α/VEGF signaling pathway on cerebral I/R injury rats.