Src regulates angiogenic factors and vascular permeability after focal cerebral ischemia-reperfusion

IL-17A Aggravated Blood-Brain Barrier Disruption via Activating Src Signaling in Epilepsy Mice

Inflammation is an important pathogenic driving force in the genesis and development of epilepsy. The latest researches demonstrated that IL-17A mediated blood-brain barrier (BBB) dysfunction through disruption of tight junction protein expression. To investigate whether IL-17A is involved in BBB disruption after acute seizure attack, the pilocarpine model was established with C57BL/6 J (wild type, WT) and IL-17R-deficient mice in vivo and with primary cultured rat brain microvascular endothelial cells in vitro. The mortality rate and brain water content were evaluated at 24 h after status epilepticus, and IL-17A concentration, endothelial tight junction, adherens junction proteins, and albumin leakage were assessed at 0 h, 4 h, 12 h, and 24 h after status epilepticus (SE). IL-17R-deficient mice showed lessen severity of epilepsy than WT mice, accompanied by less albumin leakage, reduced brain water content, decreased IL-17A, and upregulated expression of target proteins (ZO-1, Occludin and VE-cadherin). IL-17R knockout abrogated abnormal upregulation of Src kinase and phosphorylated Src kinase in the setting of SE, and Src kinase inhibitor PP1 abrogated IL-17A-induced SE related endothelial injury in vitro. In conclusion, IL-17A inhibition might be a promising therapeutic option to attenuate endothelial cell injury and further BBB disruption by reducing Src kinase activation.

The therapeutic effects of salvianolic acids on ischemic stroke: From molecular mechanisms to clinical applications

Ischemic stroke (IS), primarily caused by cerebrovascular occlusion, poses a significant public health challenge with limited effective therapeutic options. Evidence suggests that salvianolic acids (SAs), mainly from Salvia miltiorrhiza Bunge, have been formulated into injections and are widely used in clinical treatments for cardiovascular and cerebrovascular diseases, including stroke. The pharmacological properties of SAs include reducing neuroinflammation, alleviating oxidative stress injury, inhibiting cellular apoptosis, preserving endothelial function, maintaining blood-brain barrier integrity, and promoting angiogenesis. Salvianolic acids for injection (SAFI) serve as a safe and effective treatment option for cardiovascular and cerebrovascular conditions by influencing various signaling pathways and molecular targets associated with these diseases. In this review, we first discuss the pathogenesis of IS, then summarize the classification of SAs, elaborate detailed molecular mechanisms of their efficacy, and the related clinical applications of SAFI. We also emphasize the recent pharmacological advancements and therapeutic possibilities of this promising drug preparation derived from herbs for cerebrovascular conditions.

Identification of active ingredients in Naomaitai capsules using high-resolution mass spectrometry unite molecular network analysis and prediction of their action mechanisms

RATIONALE

Although Naomaitai capsule (NMC) is widely used in clinical practice and has a good curative effect for cerebral infarction, its material basis and mechanism of action remain unclear.

METHODS

In this study, ultra-high-performance liquid chromatography (UHPLC) coupled with quadrupole Orbitrap MS technology was used to analyse the in vivo and in vitro components of NMC, and the Global Natural Products Social Molecular Networking website was used to further analyse the components of NMC. Next, systems biology approaches were employed to investigate the mechanism of action of NMC. Finally, molecular docking technology was used to verify the network pharmacological results.

RESULTS

In total, 177 compounds were identified in vitro, including 65 terpenoids, 62 flavonoids, 25 organic acids and 11 quinones. 64 compounds were identified in the blood of mice, and the main active components included ginkgolide C, ginkgolide A, ligustilide, tanshinone IIB, olmelin, emodin and puerarin. The main targets in vivo included TP53, SRC, STAT3, PIK3CA and PIK3R1.

CONCLUSIONS

In conclusion, this study has revealed that NMC acts on multiple targets in the body through various active components, exerting synergistic effects in the treatment of CI. Its mechanism of action may involve inhibiting neuronal apoptosis, oxidative stress and inflammatory responses as well as reducing cerebral vascular permeability and promoting cerebral vascular regeneration.

GLP-1 programs the neurovascular landscape

Readily available nutrient-rich foods exploit our inherent drive to overconsume, creating an environment of overnutrition. This transformative setting has led to persistent health issues, such as obesity and metabolic syndrome. The development of glucagon-like peptide-1 receptor (GLP-1R) agonists reveals our ability to pharmacologically manage weight and address metabolic conditions. Obesity is directly linked to chronic low-grade inflammation, connecting our metabolic environment to neurodegenerative diseases. GLP-1R agonism in curbing obesity, achieved by impacting appetite and addressing associated metabolic defects, is revealing additional benefits extending beyond weight loss. Whether GLP-1R agonism directly impacts brain health or does so indirectly through improved metabolic health remains to be elucidated. In exploring the intricate connection between obesity and neurological conditions, recent literature suggests that GLP-1R agonism may have the capacity to shape the neurovascular landscape. Thus, GLP-1R agonism emerges as a promising strategy for addressing the complex interplay between metabolic health and cognitive well-being.

Novel insight into the role of A-kinase anchoring proteins (AKAPs) in ischemic stroke and therapeutic potentials

Ischemic stroke, a devastating disease associated with high mortality and disability worldwide, has emerged as an urgent public health issue. A-kinase anchoring proteins (AKAPs) are a group of signal-organizing molecules that compartmentalize and anchor a wide range of receptors and effector proteins and have a major role in stabilizing mitochondrial function and promoting neurodevelopmental development in the central nervous system (CNS). Growing evidence suggests that dysregulation of AKAPs expression and activity is closely associated with oxidative stress, ion disorder, mitochondrial dysfunction, and blood-brain barrier (BBB) impairment in ischemic stroke. However, the underlying mechanisms remain inadequately understood. This review provides a comprehensive overview of the composition and structure of A-kinase anchoring protein (AKAP) family members, emphasizing their physiological functions in the CNS. We explored in depth the molecular and cellular mechanisms of AKAP complexes in the pathological progression and risk factors of ischemic stroke, including hypertension, hyperglycemia, lipid metabolism disorders, and atrial fibrillation. Herein, we highlight the potential of AKAP complexes as a pharmacological target against ischemic stroke in the hope of inspiring translational research and innovative clinical approaches.

Hyperforin ameliorates neuroinflammation and white matter lesions by regulating microglial VEGFR2 /SRC pathway in vascular cognitive impairment mice

AIM

To explore the neuroprotective potential of hyperforin and elucidate its underlying molecular mechanisms involved in its therapeutic effects against vascular cognitive impairment (VCI).

METHODS

The active compounds and possible targets of Hypericum perforatum L. that may be effective against VCI were found by network pharmacology in this research. We utilized bilateral common carotid artery occlusion (BCCAO) surgery to induce a VCI mouse model. Morris water maze (MWM) and Y-maze tests were used to assess VCI mice's cognitive abilities following treatment with hyperforin. To evaluate white matter lesions (WMLs), we utilized Luxol fast blue (LFB) stain and immunofluorescence (IF). Neuroinflammation was assessed using IF, western blot (WB), and enzyme-linked immunosorbent assay (ELISA). The effects of hyperforin on microglia were investigated by subjecting the BV2 microglial cell line to oxygen-glucose deprivation/reperfusion (OGD/R) stimulation. The expressions of VEGFR2 , p-SRC, SRC, VEGFA, and inflammatory markers including IL-10, IL-1β, TNF-α, and IL-6 were subsequently assessed.

RESULTS

The VEGFR2 /SRC signaling pathway is essential for mediating the protective properties of hyperforin against VCI according to network pharmacology analysis. In vivo findings demonstrated that hyperforin effectively improved BCCAO-induced cognitive impairment. Furthermore, staining results showed that hyperforin attenuated WMLs and reduced microglial activation in VCI mice. The hyperforin treatment group's ELISA results revealed a substantial decrease in IL-1β, IL-6, and TNF-α levels. According to the results of in vitro experiments, hyperforin decreased the release of pro-inflammatory mediators (TNF-α, IL-6, and IL-1β) and blocked microglial M1-polarization by modulating the VEGFR2 /SRC signaling pathway.

CONCLUSION

Hyperforin effectively modulated microglial M1 polarization and neuroinflammation by inhibiting the VEGFR2 /SRC signaling pathways, thereby ameliorating WMLs and cognitive impairment in VCI mice.

Environmental Enrichment for Stroke and Traumatic Brain Injury: Mechanisms and Translational Implications

Acquired brain injuries, such as ischemic stroke, intracerebral hemorrhage (ICH), and traumatic brain injury (TBI), can cause severe neurologic damage and even death. Unfortunately, currently, there are no effective and safe treatments to reduce the high disability and mortality rates associated with these brain injuries. However, environmental enrichment (EE) is an emerging approach to treating and rehabilitating acquired brain injuries by promoting motor, sensory, and social stimulation. Multiple preclinical studies have shown that EE benefits functional recovery, including improved motor and cognitive function and psychological benefits mediated by complex protective signaling pathways. This article provides an overview of the enriched environment protocols used in animal models of ischemic stroke, ICH, and TBI, as well as relevant clinical studies, with a particular focus on ischemic stroke. Additionally, we explored studies of animals with stroke and TBI exposed to EE alone or in combination with multiple drugs and other rehabilitation modalities. Finally, we discuss the potential clinical applications of EE in future brain rehabilitation therapy and the molecular and cellular changes caused by EE in rodents with stroke or TBI. This article aims to advance preclinical and clinical research on EE rehabilitation therapy for acquired brain injury. © 2024 American Physiological Society. Compr Physiol 14:5291-5323, 2024.

The early predictive value of platelet-to-lymphocyte ratio to hemorrhagic transformation of young acute ischemic stroke

Background

The increasing incidence of acute ischemic stroke (AIS) necessitates a comprehensive understanding of the related factors. Hemorrhagic transformation (HT), a severe complication of AIS, is influenced by platelet-induced inflammation and lymphocyte levels.

Objective

To measure the predictive value of platelet-to-lymphocyte ratio (PLR) in the occurrence of HT in young AIS patients.

Methods

Data of young AIS patients (n = 157) admitted to the hospital for the first time were retrospectively collected. The patients were divided into HT (63 patients) and non-HT groups (94 patients) on the basis of whether HT had occurred after admission. The National Institute of Health stroke scale (NIHSS) score was used to determine the severity of clinical symptoms. The relationship between PLR and HT and NIHSS scores was analyzed to evaluate the predictive value of PLR in the occurrence of HT using receiver operating characteristic (ROC) and area under the curve (AUC).

Results

Multivariate analysis showed that PLR and NIHSS are independent risk factors of HT. The PLR value of the observation group was positively associated with the NIHSS score (r = 0.8075, P < 0.0001). According to the PLR prediction about the occurrence of HT, an AUC of 0.713 (95% CI, 0.652-0.781), a cut-off value of 109.073, and a sensitivity and specificity of 0.806 and 0.674, respectively, were obtained.

Conclusions

PLR value can predict the possibility of HT in young AIS patients to a certain extent. To take effective measures to prevent HT in advance has crucial clinical significance according to PLR value.

Compound musk injection in the treatment of ischemic stroke: A network analysis of the mechanism of action

BACKGROUND

Ischemic stroke (IS) is affected by a wide range of factors and has certain treatment limitations. Studies have reported that compound musk injection (CMI) is effective in the treatment of IS, however, its mechanism of action is still unclear.

METHODS

The main active ingredients in CMI were retrieved from HERB, TCMSP and BATMAN databases, and the relevant targets were predicted by Swiss Target Prediction platform. MalaCards, OMIM, DrugBank, DisGeNET, Genecards and TTD databases were used to obtain the genes related to IS. The intersection of drugs and disease targets was used to construct protein-protein interaction networks, and gene ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were performed. AutoDock Vina software was used for molecular docking, and cell experiments were conducted to verify the results. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the expression level of relative mRNA in cells.

RESULTS

Network analysis and molecular docking results showed that the key targets of CMI in the treatment of IS were SRC, TP53, PIK3R1, MAPK3, PIK3CA, MAPK1, etc. KEGG pathway enrichment analysis mainly involved PI3K/Akt signaling pathway, Rap1 signaling pathway and MAPK signaling pathway. The molecular docking results all showed that the key ingredients were strong binding activity with the key targets. The quantitative RT-PCR results indicated that CMI may increase the expression of PIK3CA, MAPK3 mRNA and decrease the expression of SRC mRNA.

CONCLUSIONS

CMI can treat IS by regulating pathways and targets related to inflammatory response and apoptosis in a multi-component manner.

Neural Stem Cell Extracellular Vesicles Carrying YBX1 Inhibited Neuronal Pyroptosis Through Increasing m6A-modified GPR30 Stability and Expression in Ischemic Stroke

Neural stem cell-derived extracellular vesicles (NSC-derived EVs) alleviated ischemic stroke (IS) by suppressing the activation of nucleotide-binding domain leucine-rich repeats family protein 3 (NLRP3) inflammasome and neuronal pyroptosis. However, the specific mechanism needs further investigation. qRT-qPCR, Western blotting, and immunofluorescence detected related gene expression. Immunofluorescent analyzed the expression of Ki-67, βIII-Tubulin (Tuj1), and GFAP. Lactate dehydrogenase (LDH) release and IL-1β and IL-18 levels were analyzed by LDH and ELISA kits. TTC staining evaluated the infarction of brain tissues. Flow cytometric analysis measured caspase-1 activity. M6A methylated RNA immunoprecipitation PCR (MeRIP-PCR) measured methylation levels of G protein-coupled receptor 30 (GPR30). RIP and Co-IP analyzed the interactions of Y box binding protein (YBX1)/GPR30, YBX1/IGF2BP1 and NLRP3/speckle-type POZ protein (SPOP), as well as the ubiquitination levels of NLRP3. NSC-derived EVs inhibited the ischemia-reperfusion (I/R) injury of rats and the neuronal pyroptosis induced by oxygen-glucose deprivation/reoxygenation (OGD/R). Knockdown of EVs carrying YBX1 or GPR30 silencing abolished these inhibiting effects. GPR30 mRNA and IGF2BP1 protein were enriched by YBX1 antibody. YBX1 enhanced the stability of m6A-modified GPR30 by interacting with IGF2BP1 and thus promoting GPR30 expression. Knockdown of IGF2BP1 suppressed the binding between YBX1 and GPR30 mRNA. GPR30 promoted NLRP3 ubiquitination by interacting with SPOP. EVs carrying YBX1 could reduce the infarction of brain tissues and inhibit neuronal pyroptosis in rats with I/R injury. NSC-derived EVs carrying YBX1 increased the stability of m6A-modified GPR30 by interacting with IGF2BP1; the upregulation of GPR30 inhibited the activation of NLRP3 inflammasome through promoting NLRP3 ubiquitination by SPOP, ultimately suppressing the neuronal pyroptosis in IS.

Effect of VEGF on neurological impairment and prognosis of acute cerebral infarction patients: A retrospective case-control study

OBJECTIVE

Due to the complex pathological mechanism of acute cerebral infarction, the role of vascular endothelial growth factor (VEGF) on the disease is not clear. Therefore, a retrospective case-control study was performed to explore the effect of VEGF on neurological impairment and prognosis of acute cerebral infarction patients.

METHOD

A total of 100 patients with acute cerebral infarction admitted to our hospital from April 2021 to April 2022 were selected. Blood samples from all patients would be routinely collected to detect the expression of serum VEGF. Pearson chi-square, Spearman correlation and univariate Logistic regression were used to analyze the clinical data to explore the relationship between VEGF expression and basic information, stroke degree, quality of life, and prognosis of patients. To determine whether VEGF can provide relevant basis for the early prevention and prognostic treatment of acute cerebral infarction. And multivariate logistic regression was used to calculate the odds ratio between each variable and VEGF expression.

RESULTS

Pearson chi-square test and Spearman correlation coefficient showed that sex, degree of stroke, limb convulsions, loss of consciousness, hemiplegia, aphasia, mental functioning score, overall quality of life score, and short-term prognosis were significantly correlated with VEGF expression in 100 patients. Univariate logistic regression was used to describe the ORs and 95% confidence interval of subjects at the univariate level, and the degree of stroke (OR = 83.333, P < 0.001), tic of limbs (OR = 26.316, P < 0.001), loss of consciousness (OR = 23.256, P < 0.001), hemiplegia (OR = 62.500, P < 0.001), aphasia (OR = 76.923, P < 0.001), mental functioning score (OR = 7.937, P < 0.001), overall quality of life score (OR = 5.464, P < 0.001), short-term prognosis (OR = 37.037, P < 0.001) was significantly correlated with the high expression of VEGF.

CONCLUSIONS

The level of serum VEGF was positively correlated with neurological impairment degree and prognosis in patients with acute cerebral infarction, the more severe the degree of stroke and the worse the prognosis.

Integrating network pharmacology and pharmacological evaluation to explore the protective mechanism of Ershiwuwei Zhenzhu pill in ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Ershiwuwei Zhenzhu Pill (EZP), a representative and classic formula in Tibetan medicine, is commonly used in the treatment of various cerebrovascular diseases, including ischemic stroke (IS). Nevertheless, their efficacy and potential mechanism in treating IS have yet to be investigated.

AIM OF THE STUDY

This study aimed to investigate the potential mechanisms of EZP in the treatment of IS based on network pharmacology and experimental verification.

MATERIALS AND METHODS

The chemical profile of EZP was characterized using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The targets related to the compounds in EZP were predicted by the Swiss Target Prediction and Target Net platform, and targets of IS were collected from the Gene Cards and OMIM databases. Subsequently, a protein-protein interaction (PPI) network of targets was constructed and analyzed by the STRING database and Cytoscape software, version 3.7.1. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed, and an ingredient-target-pathway network was constructed. Ultimately, the middle cerebral artery occlusion (MCAO) model was established to evaluate the anti-IS effects of EZP by detecting the neurological deficit score, HE, Nissl and TCC staining, and inflammatory factors, and the expression of key protein targets was detected by western blotting.

RESULTS

A total of 129 components were identified in EZP. Network pharmacology revealed 3136 compound targets and 2826 disease-related targets, and 412 overlapping proteins were obtained as potential therapeutic targets. The PPI network results showed that 6 key targets (AKT1, SRC, VEGFA, TP53, TNF and EGFR) were core targets of EZP in the treatment of IS. Western blotting demonstrated that the expression levels of AKT1, VEGFA, TP53, SRC, TNF and EGFR in the brain tissue of MCAO rats were significantly changed after treatment with EZP compared to the model group.

CONCLUSIONS

EZP ameliorated IS in MCAO rats. The underlying mechanism might be associated with inhibiting inflammation and apoptosis, promoting angiogenesis and protecting neurons by regulating multiple targets and pathways.

Inhibiting SRC activity attenuates kainic-acid induced mouse epilepsy via reducing NR2B phosphorylation and full-length NR2B expression

OBJECTIVE

To explore the effect of SRC activation on spontaneously recurrent seizures and to investigate the underlying mechanisms of NR2B phosphorylation.

METHODS

C57BL/6 mice were injected intrahippocampally with kainic acid (KA, 0.4 μg/25 g) to induce status epilepticus (SE). Saracatinib(STB) was used as an SRC inhibitor. Spontaneously recurrent seizures were monitored from day 7 to day 14 after the KA injection. Nissl's stain and NeuN were used to detect neuron loss and Timm stain was used to evaluate mossy fibre sprouting 14 days after KA injection. We also investigated the effect of SRC on full-length expression of NR2B. MDL28170 was used to inhibit calpain activity. Western blotting and qPCR were performed to verify phosphorylation levels and expression of SRC and NR2B 24 h after KA injection.

RESULTS

The duration of status epileptics in the SRC inhibitor group decreased significantly compared to the KA group 24 h after the injection of KA (P < 0.05). The application of the SRC inhibitor significantly reduced the degree of contralateral mossy fibre sprouting (P < 0.05) and improved the degree of neuron loss (P < 0.01) compared to the epilepsy group. Full-length NR2B levels in the ipsilateral hippocampus decreased in the epilepsy group (P < 0.01) compared to the sham group, and it further decreased in the STB inhibitor group (P < 0.01). The effect of the STB inhibitor was counteracted by simultaneous inhibition of SRC activity and calpain activation, while the level of full-length NR2B increased compared to the KA+STB group(P < 0.01). Reduction of NR2B cleavage by MDL28170 significantly increased the duration of epileptic status compared to the KA group (P < 0.05).

SIGNIFICANCE

Our data indicated that the early application of SRC inhibitors exerted protective effects on seizure severity, loss of neurons, and sprouting of mossy fibres in KA-induced mouse epilepsy. Seizure severity attenuation due to SRC inhibition was associated with the decrease of NR2B in both the phosphorylation and full-length forms.

GLP-1R Agonist Exendin-4 Protects Against Hemorrhagic Transformation Induced by rtPA After Ischemic Stroke via the Wnt/β-Catenin Signaling Pathway

Tissue plasminogen activator (tPA) is recommended by the FDA to dissolve intravascular clots after acute ischemic stroke (AIS). However, it may contribute to hemorrhagic transformation (HT). The Wnt/β-catenin signaling pathway plays an important role in regulating the blood–brain barrier (BBB) formation in the central nervous system. We explored whether glucagon-like peptide-1 receptor (GLP-1R) agonist exendin-4 (EX-4) reduces the risk of HT after rtPA treatment via the Wnt/β-catenin pathway by using a rat transient middle cerebral artery occlusion (MCAO) model in vivo and an oxygen–glucose deprivation plus reoxygenation (OGD/R) model in vitro. Our results showed that EX-4 attenuated neurological deficits, brain edema, infarct volume, BBB disruption, and rtPA-induced HT in ischemic stroke. EX-4 suppressed the production of ROS and the activation of MMP-9 to protect the integrity of the BBB by activating the Wnt/β-catenin signaling pathway. PRI-724, a selective inhibitor of β-catenin, was able to reverse the therapeutic effect of EX-4 in vivo and in vitro. Therefore, our results indicate that the GLP-1R agonist may be a potential therapeutic agent to decrease the risk of rtPA-induced HT after ischemic stroke via the Wnt/β-catenin signaling pathway.

Repair Mechanisms of the Neurovascular Unit after Ischemic Stroke with a Focus on VEGF

The functional neural circuits are partially repaired after an ischemic stroke in the central nervous system (CNS). In the CNS, neurovascular units, including neurons, endothelial cells, astrocytes, pericytes, microglia, and oligodendrocytes maintain homeostasis; however, these cellular networks are damaged after an ischemic stroke. The present review discusses the repair potential of stem cells (i.e., mesenchymal stem cells, endothelial precursor cells, and neural stem cells) and gaseous molecules (i.e., nitric oxide and carbon monoxide) with respect to neuroprotection in the acute phase and regeneration in the late phase after an ischemic stroke. Commonly shared molecular mechanisms in the neurovascular unit are associated with the vascular endothelial growth factor (VEGF) and its related factors. Stem cells and gaseous molecules may exert therapeutic effects by diminishing VEGF-mediated vascular leakage and facilitating VEGF-mediated regenerative capacity. This review presents an in-depth discussion of the regeneration ability by which endogenous neural stem cells and endothelial cells produce neurons and vessels capable of replacing injured neurons and vessels in the CNS.

Neuroprotection of Heme Oxygenase-2 in Mice AfterIntracerebral Hemorrhage

There are few effective preventive or therapeutic strategies to mitigate the effects of catastrophic intracerebral hemorrhage (ICH) in humans. Heme oxygenase is the rate-limiting enzyme in heme metabolism; heme oxygenase-2 (HO-2) is a constitutively expressed heme oxygenase. We explored the involvement of HO-2 in a collagenase-induced mouse model of ICH in C57BL/6 wild-type and HO-2 knockout mice. We assessed oxidative stress injury, blood-brain barrier permeability, neuronal damage, late-stage angiogenesis, and hematoma clearance using immunofluorescence, Western blot, MRI, and special staining methods. Our results show that HO-2 reduces brain injury volume and brain edema, alleviates cytotoxic injury, affects vascular function in the early stage of ICH, and improves hematoma absorbance and angiogenesis in the late stage of ICH in this model. Thus, we found that HO-2 has a protective effect on brain injury after ICH.

Delayed Exercise-induced Upregulation of Angiogenic Proteins and Recovery of Motor Function after Photothrombotic Stroke in Mice

Treatments promoting post-stroke functional recovery continue to be an unmet therapeutic problem with physical rehabilitation being the most reproduced intervention in preclinical and clinical studies. Unfortunately, physiotherapy is typically effective at high intensity and early after stroke - requirements that are hardly attainable by stroke survivors. The aim of this study was to directly evaluate and compare the dose-dependent effect of delayed physical rehabilitation (daily 5 h or overnight voluntary wheel running; initiated on post-stroke day 7 and continuing through day 21) on recovery of motor function in the mouse photothrombotic model of ischemic stroke and correlate it with angiogenic potential of the brain. Our observations indicate that overnight but not 5 h access to running wheels facilitates recovery of motor function in mice in grid-walking test. Western blotting and immunofluorescence microscopy experiments evaluating the expression of angiogenesis-associated proteins VEGFR2, doppel and PDGFRβ in the peri-infarct and corresponding contralateral motor cortices indicate substantial upregulation of these proteins (≥2-fold) in the infarct core and surrounding cerebral cortex in the overnight running mice on post-stroke day 21. These findings indicate that there is a dose-dependent relationship between the extent of voluntary exercise, motor recovery and expression of angiogenesis-associated proteins in this expert-recommended mouse ischemic stroke model. Notably, our observations also point out to enhanced angiogenesis and presence of pericytes within the infarct core region during the chronic phase of stroke, suggesting a potential contribution of this tissue area in the mechanisms governing post-stroke functional recovery.

Salvianolic acid A prevented cerebrovascular endothelial injury caused by acute ischemic stroke through inhibiting the Src signaling pathway

Stroke is an acute cerebrovascular disease caused by ruptured or blocked blood vessels. For the prevention of ischemic stroke, the coagulation state of blood and cerebrovascular protection should be considered. Our previous study has shown that salvianolic acid A (SAA), which is a water-soluble component from the root of Salvia Miltiorrhiza Bge, prevents thrombosis with a mild inhibitory effect on platelet aggregation. In this study we investigated the preventive effects of SAA on cerebrovascular endothelial injury caused by ischemia in vivo and oxygen-glucose deprivation (OGD) in vitro, and explored the underlying mechanisms. An autologous thrombus stroke model was established in SD rats by electrocoagulation. SAA (10 mg/kg) was orally administered twice a day for 5 days before the operation. The rats were sacrificed at 24 h after the operation. We showed that pretreatment with SAA significantly improved the neurological deficits, intracerebral hemorrhage, BBB disruption, and vascular endothelial dysfunction as compared with model group. In human brain microvascular endothelial cells (HBMECs), pretreatment with SAA (10 μM) significantly inhibited OGD-induced cell viability reduction and degradation of tight junction proteins (ZO-1, occludin, claudin-5). Furthermore, we found that SAA inhibited the upregulation of Src signaling pathway in vivo and vitro and reversed the increased expression of matrix metalloproteinases (MMPs) after ischemic stroke. In conclusion, our results suggest that SAA protects cerebrovascular endothelial cells against ischemia and OGD injury via suppressing Src signaling pathway. These findings show that pretreatment with SAA is a potential therapeutic strategy for the prevention of ischemic stroke.

Mechanism of Radix Rhei Et Rhizome Intervention in Cerebral Infarction: A Research Based on Chemoinformatics and Systematic Pharmacology

OBJECTIVE

To explore the therapeutic targets, network modules, and coexpressed genes of Radix Rhei Et Rhizome intervention in cerebral infarction (CI), and to predict significant biological processes and pathways through network pharmacology. To explore the differential proteins of Radix Rhei Et Rhizome intervention in CI, conduct bioinformatics verification, and initially explain the possible therapeutic mechanism of Radix Rhei Et Rhizome intervention in CI through proteomics.

METHODS

The TCM database was used to predict the potential compounds of Radix Rhei Et Rhizome, and the PharmMapper was used to predict its potential targets. GeneCards and OMIM were used to search for CI-related genes. Cytoscape was used to construct a protein-protein interaction (PPI) network and to screen out core genes and detection network modules. Then, DAVID and Metascape were used for enrichment analysis. After that, in-depth analysis of the proteomics data was carried out to further explore the mechanism of Radix Rhei Et Rhizome intervention in CI.

RESULTS

(1) A total of 14 Radix Rhei Et Rhizome potential components and 425 potential targets were obtained. The core components include sennoside A, palmidin A, emodin, toralactone, and so on. The potential targets were combined with 297 CI genes to construct a PPI network. The targets shared by Radix Rhei Et Rhizome and CI include ALB, AKT1, MMP9, IGF1, CASP3, etc. The biological processes that Radix Rhei Et Rhizome may treat CI include platelet degranulation, cell migration, fibrinolysis, platelet activation, hypoxia, angiogenesis, endothelial cell apoptosis, coagulation, and neuronal apoptosis. The signaling pathways include Ras, PI3K-Akt, TNF, FoxO, HIF-1, and Rap1 signaling pathways. (2) Proteomics shows that the top 20 proteins in the differential protein PPI network were Syp, Syn1, Mbp, Gap43, Aif1, Camk2a, Syt1, Calm1, Calb1, Nsf, Nefl, Hspa5, Nefh, Ncam1, Dcx, Unc13a, Mapk1, Syt2, Dnm1, and Cltc. Differential protein enrichment results show that these proteins may be related to synaptic vesicle cycle, vesicle-mediated transport in synapse, presynaptic endocytosis, synaptic vesicle endocytosis, axon guidance, calcium signaling pathway, and so on.

CONCLUSION

This study combined network pharmacology and proteomics to explore the main material basis of Radix Rhei Et Rhizome for the treatment of CI such as sennoside A, palmidin A, emodin, and toralactone. The mechanism may be related to the regulation of biological processes (such as synaptic vesicle cycle, vesicle-mediated transport in synapse, presynaptic endocytosis, and synaptic vesicle endocytosis) and signaling pathways (such as Ras, PI3K-Akt, TNF, FoxO, HIF-1, Rap1, and axon guidance).

Acorus tatarinowii Schott extract reduces cerebral edema caused by ischemia-reperfusion injury in rats: involvement in regulation of astrocytic NKCC1/AQP4 and JNK/iNOS-mediated signaling

Background

This study aimed to evaluate the effects of the Acorus tatarinowii Schott [Shi Chang Pu (SCP)] extract administered at the start of 2 h of middle cerebral artery occlusion (MCAo), followed by 3 d of reperfusion, and to determine mechanisms involved in anti-edema effects in the penumbra of the cerebral cortex.

Method

Rats were intraperitoneally administered the SCP extract at a dose of 0.25 g/kg (SCP-0.25 g), 0.5 g/kg (SCP-0.5 g), or 1 g/kg (SCP-1 g) at the start of MCAo.

Result

SCP-0.5 g and SCP-1 g treatments effectively reduced the cerebral infarct size, ameliorated cerebral edema, reduced blood–brain barrier permeability, and restored neurological function. SCP-0.5 g and SCP-1 g treatments markedly downregulated the levels of glial fibrillary acidic protein, Na⁺-K⁺-2Cl⁻ cotransporter type 1 (NKCC1), aquaporin 4 (AQP4), phospho-c-Jun N-terminal kinase (p-JNK)/JNK, inducible nitric oxide synthase (iNOS), 3-nitrotyrosine, intercellular adhesion molecule-1 (ICAM-1), matrix metalloproteinase-9 (MMP-9), vascular endothelial growth factor-A (VEGF-A), and zonula occluden-1 (ZO-1) and upregulated ZO-3 expression in the penumbra of the cerebral cortex 3 d after reperfusion.

Conclusions

SCP-0.5 g and SCP-1 g treatments exert neuroprotective effects against cerebral infarction and cerebral edema partially by mitigating astrocytic swelling and blood–brain barrier disruption. Moreover, the anti-cerebral edema effects of SCP extract treatments are possibly associated with the downregulation of astrocytic NKCC1/AQP4 and JNK/iNOS-mediated ICAM-1/MMP-9 signaling in the penumbra of the cerebral cortex 3 d after reperfusion.

Hydrogen Sulfide Overproduction Is Involved in Acute Ischemic Cerebral Injury Under Hyperhomocysteinemia

Objectives

This study aimed to identify the involvement of hydrogen sulfide overproduction in acute brain injury under ischemia/reperfusion and hyperhomocysteinemia.

Methods

In vitro and in vivo experiments were conducted to determine: the effect of sodium hydrosulfide treatment on the human neuroblastoma cell line (SH-SY5Y) under conditions of oxygen and glucose deprivation; the changes of hydrogen sulfide levels, inflammatory factors, energetic metabolism, and mitochondrial function in the brain tissue of rats under either ischemia/reperfusion alone or a combination of ischemia/reperfusion and hyperhomocysteinemia; and the potential mechanism underlying the relationship between homocysteine and these changes through the addition of the related inhibitors. Furthermore, experimental technologies, including western blot, enzyme-linked immunosorbent assay, immunofluorescence, reverse transcription polymerase chain reaction, and flow cytometry, were used.

Results

Our study found that high concentration of sodium hydrosulfide treatment aggravated the decrease in mitochondrial membrane potential, the increase in both mitochondrial permeability transition pore and translocation of cytochrome C, as well as the accumulation of reactive oxygen species in oxygen and glucose deprived SH-SY5Y cells. As a result, neurological deficit appeared in rats with ischemia/reperfusion or ischemia/reperfusion and hyperhomocysteinemia, and a higher water content and larger infarction size of cerebral tissue appeared in rats combined ischemia/reperfusion and hyperhomocysteinemia. Furthermore, alterations in hydrogen sulfide production, inflammatory factors, and mitochondria morphology and function were more evident under the combined ischemia/reperfusion and hyperhomocysteinemia. These changes were, however, alleviated by the addition of inhibitors for CBS, CSE, Hcy, H₂S, and NF-κB, although at different levels. Finally, we observed a negative relationship between the blockage of: (a) the nuclear factor kappa-B pathway and the levels of cystathionine β-synthase and hydrogen sulfide; and (b) the hydrogen sulfide pathway and the levels of inflammatory factors.

Conclusion

Hydrogen sulfide overproduction and reactive inflammatory response are involved in ischemic cerebral injury under hyperhomocysteinemia. Future studies in this direction are warranted to provide a scientific base for targeted medicine development.

Neuroprotective and Neurorestorative Effects of Epo and VEGF: Perspectives for New Therapeutic Approaches to Neurological Diseases

BACKGROUND

Erythropoietin (Epo) and vascular endothelial growth factor (VEGF) are two vasoactive molecules with essential trophic effects for brain development. The expression and secretion of both molecules increase in response to neuronal damage and they exert protective and restorative effects, which may also be accompanied by adverse side effects.

OBJECTIVE

We review the most relevant evidence on the neuroprotective and neurorestorative effects of Epo and VEGF in three of the most frequent neurological disorders, namely, stroke, epilepsy and Alzheimer's disease, to develop new therapeutic approaches.

METHODS

Several original scientific manuscripts and reviews that have discussed the evidence in critical way, considering both the beneficial and adverse effects of Epo and VEGF in the selected neurological disorders, were analysed. In addition, throughout this review, we propose several considerations to take into account in the design of therapeutic approaches based on Epo and VEGF signalling.

RESULTS

Although the three selected disorders are triggered by different mechanisms, they evolve through similar processes: excitotoxicity, oxidative stress, neuroinflammation, neuronal death, glial reactivity and vascular remodelling. Epo and VEGF exert neuroprotective and neurorestorative effects by acting on these processes due to their pleiotropism. In general, the evidence shows that both Epo and VEGF reduce neuronal death but that at the vascular level, their effects are contradictory.

CONCLUSION

Because the Epo and VEGF signalling pathways are connected in several ways, we conclude that more experimental studies, primarily studies designed to thoroughly assess the functional interactions between Epo and VEGF in the brain under both physiological and pathophysiological conditions, are needed.

Safety and efficacy of remote ischemic postconditioning after thrombolysis in patients with stroke

OBJECTIVE

To determine the effect of remote ischemic postconditioning (RIPC) on patients with acute ischemic stroke (AIS) undergoing IV thrombolysis (IVT).

METHODS

A single-center randomized controlled trial was performed with patients with AIS receiving IVT. Patients in the RIPC group were administered RIPC treatment (after IVT) during hospitalization. The primary endpoint was a score of 0 or 1 on the modified Rankin scale (mRS) at day 90. The safety, tolerability, and neuroprotection biomarkers associated with RIPC were also evaluated.

RESULTS

We collected data from both the RIPC group (n = 34) and the control group (n = 34). The average duration of hospitalization was 11.2 days. There was no significant difference between 2 groups at admission for the NIH Stroke Scale score (p = 0.364) or occur-to-treatment time (p = 0.889). Favorable recovery (mRS score 0-1) at 3 months was obtained in 71.9% of patients in the RIPC group vs 50.0% in the control group (adjusted odds ratio 9.85, 95% confidence interval 1.54-63.16; p = 0.016). We further found significantly lower plasma S100-β (p = 0.007) and higher vascular endothelial growth factor (p = 0.003) levels in the RIPC group than in the control group.

CONCLUSIONS

Repeated RIPC combined with IVT can significantly facilitate recovery of nerve function and improve clinical prognosis of patients with AIS.

CLINICALTRIALSGOV IDENTIFIER

NCT03218293.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that RIPC after tissue plasminogen activator treatment of AIS significantly increases the proportion of patients with an MRS score of 0 or 1 at 90 days.

Dl-3-n-Butylphthalide promotes neovascularization and neurological recovery in a rat model of intracerebral hemorrhage

Background

Cerebral stroke occurs following ischemic and hemorrhagic lesions in the brain. Survival and recovery of stroke patients depend on the severity of the initial injury but also the therapeutic approaches applied for emergent lifesaving and continuing post-stroke management. Dl-3-n-Butylphthalide (NBP), an active compound derived from Chinese celery seeds, has shown clinical efficacy in the treatment of ischemic cerebral stroke.

Results

In the present study we explored the therapeutic effect of NBP in a rat model of intracerebral hemorrhage (ICH), focusing on its potential role in promoting neovascularization in the perihemorrhagic zone. ICH was induced in male Sprague-Dawley rats by unilateral injection of autologous blood into the globus pallidus, with sham-operated (Sham group), vehicle-treated (ICH) and NBP-treated (at 10 and 25 mg/kg/Bid, p.o., ICH + NBP10 and ICH + NBP25, respectively) groups examined behaviorally, macroscopically, histologically and biochemically at 1, 3, 7 and 15 days (d) post operation. Rats in the ICH + NBP10 and ICH + NBP25 groups showed reduced Longa’s motor scores relative to the ICH groups at the 3 and 7d time points, while the hematoma volume was comparable in the two NBP relative to the ICH groups as measured at 7d and 15d. In the perihemorrhagic zone, the numeric density of blood vessels immunolabeled by CD34, an angiogenic marker, was greater in the ICH + NBP10 and ICH + NBP25 than ICH groups, more so in the higher dosage group, at 1, 3, 7 and 15d. Levels of the vascular endothelial growth factor (VEGF) and angiopoietins-2 (Ang-2) proteins were elevated in the NBP groups relative to the sham and vehicle controls in immunoblotting of tissue lysates from the injection region.

Conclusion

These results suggest that NBP can alleviate neurological defects following experimentally induced local brain hemorrhage, which is associated with a potential role of this drug in promoting neovascularization surrounding the bleeding loci.

Prediction of the mechanisms of action of Shenkang in chronic kidney disease: A network pharmacology study and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine provides a unique curative treatment of complex chronic diseases, including chronic kidney disease (CKD), which is not effectively treated with the current therapies. The pharmacological mechanisms of Shenkang (SK), a herbal medicine containing rhubarb (Rheum palmatum L. or R. tanguticum Maxim. ex Balf.), red sage (Salvia miltiorrhiza Bunge), safflower (Carthamus tinctorius L.), and astragalus (Astragalus mongholicus Bunge), widely used to treat CKD in China, are still unclear.

AIM OF THE STUDY

In this study, the comprehensive approach used for elucidating the pharmacological mechanisms of SK included the identification of the effective constituents, target prediction and network analysis, by investigating the interacting pathways between these molecules in the context of CKD. These results were validated by performing an in vivo study and by comparison with literature reviews.

MATERIALS AND METHODS

This approach involved the following main steps: first, we constructed a molecular database for SK and screened for active molecules by conducting drug-likeness and drug half-life evaluations; second, we used a weighted ensemble similarity drug-targeting model to accurately identify the direct drug targets of the bioactive constituents; third, we constructed compound-target, target-pathway, and target-disease networks using the Cytoscape 3.2 software and determined the distribution of the targets in tissues and organs according to the BioGPS database. Finally, the resulting drug-target mechanisms were compared with those proposed by previous research on SK and validated in a mouse model of CKD.

RESULTS

By using Network analysis, 88 potential bioactive compounds in the four component herbs of SK and 85 CKD-related targets were identified, including pathways that involve the nuclear factor-κB, mitogen-activated protein kinase, transient receptor potential, and vascular endothelial growth factor, which were categorized as inflammation, proliferation, migration, and permeability modules. The results also included different tissues (kidneys, liver, lungs, and heart) and different disease types (urogenital, metabolic, endocrine, cardiovascular, and immune diseases as well as pathological processes) closely related to CKD. These findings agreed with those reported in the literature. However, our findings with the network pharmacology prediction did not account for all the effects reported for SK found in the literature, such as regulation of the hemodynamics, inhibition of oxidative stress and apoptosis, and the involvement of the transforming growth factor-β/SMAD3, sirtuin/forkhead box protein O (SIRT/FOXO) and B-cell lymphoma-2-associated X protein pathways. The in vivo validation experiment revealed that SK ameliorated CKD through antifibrosis and anti-inflammatory effects, by downregulating the levels of vascular cell adhesion protein 1, vitamin D receptor, cyclooxygenase-2, and matrix metalloproteinase 9 proteins in the unilateral ureteral obstruction mouse model. This was consistent with the predicted target and pathway networks.

CONCLUSIONS

SK exerted a curative effect on CKD and CKD-related diseases by targeting different organs, regulating inflammation and proliferation processes, and inhibiting abnormal extracellular matrix accumulation. Thus, pharmacological network analysis with in vivo validation explained the potential effects and mechanisms of SK in the treatment of CKD. However, these findings need to be further confirmed with clinical studies.

Effect of the Recombinant Adenovirus-Mediated HIF-1 Alpha on the Expression of VEGF in the Hypoxic Brain Microvascular Endothelial Cells of Rats

OBJECTIVE

To investigate the effect of recombinant adenovirus-mediated HIF-1 alpha (HIF-1α) on the expression of vascular endothelial growth factor (VEGFA) and HIF-1α in hypoxic brain microvascular endothelial cells (BMEC) in rats.

METHODS

Primary cultured rat BMEC in vitro were treated without or with either recombinant adenovirus-mediated hypoxia-inducible factor-1 alpha (AdHIF-1α) or recombinant adenovirus empty vector (Ad) in the presence of CoCl₂ (simulating hypoxia conditions), or were grown under normoxia conditions. The expression of VEGFA and HIF-1α was analyzed at 12h, 24h, 48h and 72h incubation time, respectively. We also accessed a GEO dataset of stroke to analyze in vivo the alteration of HIF-1α and VEGFA expression, and the correlations between HIF-1α, VEGFA and CD31 mRNA levels in vascular vessels after stroke.

RESULTS

VEGFA and HIF-1α expression were significantly higher in at each time point in the AdHIF-1α than other groups (p<0.05), whereas the Ad group and hypoxia group, showed no statistically significant difference (p>0.05). Moreover, VEGFA and HIF-1α levels were significantly higher in BMEC under hypoxia conditions than normoxia conditions (p <0.05). Both HIF-1α and VEGFA expression significantly increased after stroke in vivo with 1.30 and 1.57 fold-change in log2, respectively. There were significantly positive associations between HIF-1α, VEGFA and CD31 mRNA levels in vivo after stroke.

CONCLUSION

Hypoxia-induced HIF-1α and VEGFA expression in vascular vessels, and recombinant AdHIF-1α could up-regulate VEGFA, and enhance HIF-1ααlevels in BMEC in vitro, which may play an important role in the recovery of stroke.

Advances on fluid shear stress regulating blood-brain barrier

The integrity of structure and function of blood-brain barrier (BBB) plays a central role in maintaining the homeostasis of the central nervous system. Patients with severe cerebrovascular stenosis often undergo cerebrovascular bypass surgery. However, the sharply increased fluid shear stress (FSS) after cerebrovascular bypass disrupts the physiological function of brain microvascular endothelial cells (BMECs) at the lesion site, damaging BBB and inducing intracerebral hemorrhage eventually. At present, there are great interests in cerebral vascular flow regulating the structure and function of BBB under physiological and pathological conditions, and most of studies have highlighted the importance of BMECs in BBB. Understanding of how FSS regulating BBB can promote the development of new protective and restorative cerebral vascular interventional therapy.

20-HETE synthesis inhibition promotes cerebral protection after intracerebral hemorrhage without inhibiting angiogenesis

20-HETE, an arachidonic acid metabolite synthesized by cytochrome P450 4A, plays an important role in acute brain damage from ischemic stroke or subarachnoid hemorrhage. We tested the hypothesis that 20-HETE inhibition has a protective effect after intracerebral hemorrhage (ICH) and then investigated its effect on angiogenesis. We exposed hippocampal slice cultures to hemoglobin and induced ICH in mouse brains by intrastriatal collagenase injection to investigate the protective effect of 20-HETE synthesis inhibitor N-hydroxy-N'-(4-n-butyl-2-methylphenyl)-formamidine (HET0016). Hemoglobin-induced neuronal death was assessed by propidium iodide after 18 h in vitro. Lesion volume, neurologic deficits, cell death, reactive oxygen species (ROS), neuroinflammation, and angiogenesis were evaluated at different time points after ICH. In cultured mouse hippocampal slices, HET0016 attenuated hemoglobin-induced neuronal death and decreased levels of proinflammatory cytokines and ROS. In vivo, HET0016 reduced brain lesion volume and neurologic deficits, and decreased neuronal death, ROS production, gelatinolytic activity, and the inflammatory response at three days after ICH. However, HET0016 did not inhibit angiogenesis, as levels of CD31, VEGF, and VEGFR2 were unchanged on day 28. We conclude that 20-HETE is involved in ICH-induced brain damage. Inhibition of 20-HETE synthesis may provide a viable means to mitigate ICH injury without inhibition of angiogenesis.

Brain endothelial cell junctions after cerebral hemorrhage: Changes, mechanisms and therapeutic targets

Vascular disruption is the underlying cause of cerebral hemorrhage, including intracerebral, subarachnoid and intraventricular hemorrhage. The disease etiology also involves cerebral hemorrhage-induced blood-brain barrier (BBB) disruption, which contributes an important component to brain injury after the initial cerebral hemorrhage. BBB loss drives vasogenic edema, allows leukocyte extravasation and may lead to the entry of potentially neurotoxic and vasoactive compounds into brain. This review summarizes current information on changes in brain endothelial junction proteins in response to cerebral hemorrhage (and clot-related factors), the mechanisms underlying junction modification and potential therapeutic targets to limit BBB disruption and, potentially, hemorrhage occurrence. It also addresses advances in the tools that are now available for assessing changes in junctions after cerebral hemorrhage and the potential importance of such junction changes. Recent studies suggest post-translational modification, conformational change and intracellular trafficking of junctional proteins may alter barrier properties. Understanding how cerebral hemorrhage alters BBB properties beyond changes in tight junction protein loss may provide important therapeutic insights to prevent BBB dysfunction and restore normal function.

A Current Overview of the Biological and Cellular Effects of Nanosilver

Nanosilver plays an important role in nanoscience and nanotechnology, and is becoming increasingly used for applications in nanomedicine. Nanosilver ranges from 1 to 100 nanometers in diameter. Smaller particles more readily enter cells and interact with the cellular components. The exposure dose, particle size, coating, and aggregation state of the nanosilver, as well as the cell type or organism on which it is tested, are all large determining factors on the effect and potential toxicity of nanosilver. A high exposure dose to nanosilver alters the cellular stress responses and initiates cascades of signalling that can eventually trigger organelle autophagy and apoptosis. This review summarizes the current knowledge of the effects of nanosilver on cellular metabolic function and response to stress. Both the causative effects of nanosilver on oxidative stress, endoplasmic reticulum stress, and hypoxic stress—as well as the effects of nanosilver on the responses to such stresses—are outlined. The interactions and effects of nanosilver on cellular uptake, oxidative stress (reactive oxygen species), inflammation, hypoxic response, mitochondrial function, endoplasmic reticulum (ER) function and the unfolded protein response, autophagy and apoptosis, angiogenesis, epigenetics, genotoxicity, and cancer development and tumorigenesis—as well as other pathway alterations—are examined in this review.

The Janus Face of VEGF in Stroke

The family of vascular endothelial growth factors (VEGFs) are known for their regulation of vascularization. In the brain, VEGFs are important regulators of angiogenesis, neuroprotection and neurogenesis. Dysregulation of VEGFs is involved in a large number of neurodegenerative diseases and acute neurological insults, including stroke. Stroke is the main cause of acquired disabilities, and normally results from an occlusion of a cerebral artery or a hemorrhage, both leading to focal ischemia. Neurons in the ischemic core rapidly undergo necrosis. Cells in the penumbra are exposed to ischemia, but may be rescued if adequate perfusion is restored in time. The neuroprotective and angiogenic effects of VEGFs would theoretically make VEGFs ideal candidates for drug therapy in stroke. However, contradictory to what one might expect, endogenously upregulated levels of VEGF as well as the administration of exogenous VEGF is detrimental in acute stroke. This is probably due to VEGF-mediated blood–brain-barrier breakdown and vascular leakage, leading to edema and increased intracranial pressure as well as neuroinflammation. The key to understanding this Janus face of VEGF function in stroke may lie in the timing; the harmful effect of VEGFs on vessel integrity is transient, as both VEGF preconditioning and increased VEGF after the acute phase has a neuroprotective effect. The present review discusses the multifaceted action of VEGFs in stroke prevention and therapy.

Growth differentiation factor 11 improves neurobehavioral recovery and stimulates angiogenesis in rats subjected to cerebral ischemia/reperfusion

The recent suggestion that growth differentiation factor 11 (GDF11) acts as a rejuvenation factor has remained controversial. However, in addition to its role in aging, the relationship between GDF11 and cerebral ischemia is still an important area that needs more investigation. Here we examined effects of GDF11 on angiogenesis and recovery of neurological function in a rat model of stroke. Exogenous recombinant GDF11 (rGDF11) at different doses were directly injected into the tail vein in rats subjected to cerebral ischemia/reperfusion (I/R). Neurobehavioral tests were performed, the proliferation of endothelial cells (ECs) and GDF11 downstream signal activin-like kinase 5 (ALK5) were assessed, and functional microvessels were measured. Results showed that rGDF11 at a dosage of 0.1 mg/kg/day could effectively activate cerebral angiogenesis in vivo. In addition, rGDF11 improved the modified neurological severity scores and the adhesive removal somatosensory test, promoted proliferation of ECs, induced ALK5 and increased vascular surface area and the number of vascular branch points in the peri-infarct cerebral cortex after cerebral I/R. These effects were suppressed by blocking ALK5. Our novel findings shed new light on the role of GDF11. Our results strongly suggest that GDF11 improves neurofunctional recovery from cerebral I/R injury and that this effect is mediated partly through its proangiogenic effect in the peri-infarct cerebral cortex, which is associated with ALK5. Thus, GDF11/ALK5 may represent new therapeutic targets for aiding recovery from stroke.

Hypoxia stimulates neural stem cell proliferation by increasing HIF‑1α expression and activating Wnt/β-catenin signaling

Evidence indicates that after brain injury, neurogenesis is enhanced in regions such as hippocampus, striatum, and cortex. To study the role of hypoxia-inducible factor-1 (HIF‑1α) and Wnt signaling in cerebral ischemia/hypoxia-induced proliferation of neural stem cells (NSCs), we investigated the proliferation of NSCs, expression of HIF‑1α, and activation of Wnt signaling under conditions of pathologic hypoxia in vitro. NSCs were isolated from 30-day-old Sprague-Dawley rats and subjected to 0.3% oxygen in a microaerophilic incubation system. Cell proliferation was evaluated by measuring the diameter of neurospheres and by bromodeoxyuridine incorporation assays. Real-time quantitative PCR and Western blotting were used to detect mRNA and protein levels of HIF-1α, β-catenin, and cyclin D1 in the NSCs. The results showed that hypoxia increased NSC proliferation and the levels of HIF-1α, β‑catenin, and cyclin D1 (p &lt; 0.05). Blockade of the Wnt signaling pathway decreased hypoxia-induced NSC proliferation, whereas activation of this pathway increased hypoxia-induced NSC proliferation (p &lt; 0.05). Knockdown of HIF-1α with HIF-1α siRNA decreased β‑catenin nuclear translocation and cyclin D1 expression, and inhibited proliferation of NSCs (p &lt; 0.05). These findings indicate that pathologic hypoxia stimulates NSC proliferation by increasing expression of HIF-1α and activating the Wnt/β-catenin signaling pathway. The data suggest that Wnt/β-catenin signaling may play a key role in NSC proliferation under conditions of pathologic hypoxia.

GSK-3β as a target for protection against transient cerebral ischemia

Stroke remains the leading cause of death and disability worldwide. This fact highlights the need to search for potential drug targets that can reduce stroke-related brain damage. We showed recently that a glycogen synthase kinase-3β (GSK-3β) inhibitor attenuates tissue plasminogen activator-induced hemorrhagic transformation after permanent focal cerebral ischemia. Here, we examined whether GSK-3β inhibition mitigates early ischemia-reperfusion stroke injury and investigated its potential mechanism of action. We used the rat middle cerebral artery occlusion (MCAO) model to mimic transient cerebral ischemia. At 3.5 h after MCAO, cerebral blood flow was restored, and rats were administered DMSO (vehicle, 1% in saline) or GSK-3β inhibitor TWS119 (30 mg/kg) by intraperitoneal injection. Animals were sacrificed 24 h after MCAO. TWS119 treatment reduced neurologic deficits, brain edema, infarct volume, and blood-brain barrier permeability compared with those in the vehicle group. TWS119 treatment also increased the protein expression of β-catenin and zonula occludens-1 but decreased β-catenin phosphorylation while suppressing the expression of GSK-3β. These results indicate that GSK-3β inhibition protects the blood-brain barrier and attenuates early ischemia-reperfusion stroke injury. This protection may be related to early activation of the Wnt/β-catenin signaling pathway.

Distinct role of heme oxygenase-1 in early- and late-stage intracerebral hemorrhage in 12-month-old mice

Intracerebral hemorrhage (ICH) is a devastating form of stroke with high morbidity and mortality. Heme oxygenase-1 (HO-1), the key enzyme in heme degradation, is highly expressed after ICH, but its role is still unclear. In this study, we used an HO-1 inducer and inhibitor to test the role of HO-1 in different stages of ICH in vivo and in vitro. In the early stage of ICH, high HO-1 expression worsened the outcomes of mice subjected to the collagenase-induced ICH model. HO-1 increased brain edema, white matter damage, neuronal death, and neurobehavioral deficits. Furthermore, elevated HO-1 increased inflammation, oxidative stress, matrix metalloproteinase-9/2 activity, and iron deposition. In the later stage of ICH, long-term induction of HO-1 increased hematoma absorption, angiogenesis, and recovery of neurologic function. We conclude that HO-1 activation mediates early brain damage after ICH but promotes neurologic function recovery in the later stage of ICH.

Regulatory mechanisms, prophylaxis and treatment of vascular leakage following severe trauma and shock

Vascular leakage, or increased vascular permeability, is a common but important pathological process for various critical diseases, including severe trauma, shock, sepsis, and multiple organ dysfunction syndrome (MODS), and has become one of the most important causes of death for intensive care units (ICU) patients. Currently, although there has been some progress in knowledge of the pathogenesis of these vascular disorders, the detailed mechanisms remain unclear, and effective prophylaxis and treatment are still lacking. In this study, we aimed to provide a review of the literature regarding the regulatory mechanisms and prophylaxis as well as the treatment of vascular leakage in critical diseases such as severe trauma and shock, which could be beneficial for the overall clinical treatment of vascular leakage disorders.

Cerebroprotection by the neuronal PGE2 receptor EP2 after intracerebral hemorrhage in middle-aged mice

Inflammatory responses mediated by prostaglandins such as PGE₂ may contribute to secondary brain injury after intracerebral hemorrhage (ICH). However, the cell-specific signaling by PGE₂ receptor EP2 differs depending on whether the neuropathic insult is acute or chronic. Using genetic and pharmacologic approaches, we investigated the role of EP2 receptor in two mouse models of ICH induced by intrastriatal injection of collagenase or autologous arterial whole blood. We used middle-aged male mice to enhance the clinical relevance of the study. EP2 receptor was expressed in neurons but not in astrocytes or microglia after collagenase-induced ICH. Brain injury after collagenase-induced ICH was associated with enhanced cellular and molecular inflammatory responses, oxidative stress, and matrix metalloproteinase (MMP)-2/9 activity. EP2 receptor deletion exacerbated brain injury, brain swelling/edema, neuronal death, and neurobehavioral deficits, whereas EP2 receptor activation by the highly selective agonist AE1-259-01 reversed these outcomes. EP2 receptor deletion also exacerbated brain edema and neurologic deficits in the blood ICH model. These findings support the premise that neuronal EP2 receptor activation by PGE₂ protects brain against ICH injury in middle-aged mice through its anti-inflammatory and anti-oxidant effects and anti-MMP-2/9 activity. PGE₂/EP2 signaling warrants further investigation for potential use in ICH treatment.

TLR3 ligand Poly IC Attenuates Reactive Astrogliosis and Improves Recovery of Rats after Focal Cerebral Ischemia

AIMS

Brain ischemia activates astrocytes in a process known as astrogliosis. Although this process has beneficial effects, excessive astrogliosis can impair neuronal recovery. Polyinosinic-polycytidylic acid (Poly IC) has shown neuroprotection against cerebral ischemia-reperfusion injury, but whether it regulates reactive astrogliosis and glial scar formation is not clear.

METHODS

We exposed cultured astrocytes to oxygen-glucose deprivation/reoxygenation (OGD/R) and used a rat middle cerebral artery occlusion (MCAO)/reperfusion model to investigate the effects of Poly IC. Astrocyte proliferation and proliferation-related molecules were evaluated by immunostaining and Western blotting. Neurological deficit scores, infarct volumes and neuroplasticity were evaluated in rats after transient MCAO.

RESULTS

In vitro, Poly IC inhibited astrocyte proliferation, upregulated Toll-like receptor 3 (TLR3) expression, upregulated interferon-β, and downregulated interleukin-6 production. These changes were blocked by a neutralizing antibody against TLR3, suggesting that Poly IC function is TLR3-dependent. Moreover, in the MCAO model, Poly IC attenuated reactive astrogliosis, reduced brain infarction volume, and improved neurological function. In addition, Poly IC prevented MCAO-induced reductions in soma size, dendrite length, and number of dendritic bifurcations in cortical neurons of the infarct penumbra.

CONCLUSIONS

By ameliorating astrogliosis-related damage, Poly IC is a potential therapeutic agent for attenuating neuronal damage and promoting recovery after brain ischemia.

Vascular endothelial growth factor: an attractive target in the treatment of hypoxic/ischemic brain injury

Cerebral hypoxia or ischemia results in cell death and cerebral edema, as well as other cellular reactions such as angiogenesis and the reestablishment of functional microvasculature to promote recovery from brain injury. Vascular endothelial growth factor is expressed in the central nervous system after hypoxic/ischemic brain injury, and is involved in the process of brain repair via the regulation of angiogenesis, neurogenesis, neurite outgrowth, and cerebral edema, which all require vascular endothelial growth factor signaling. In this review, we focus on the role of the vascular endothelial growth factor signaling pathway in the response to hypoxic/ischemic brain injury, and discuss potential therapeutic interventions.

Progesterone exerts neuroprotective effects and improves long-term neurologic outcome after intracerebral hemorrhage in middle-aged mice

In this study, we examined the effect of progesterone on histopathologic and functional outcomes of intracerebral hemorrhage (ICH) in 10- to 12-month-old mice. Progesterone or vehicle was administered by intraperitoneal injection 1 hour after collagenase-induced ICH and then by subcutaneous injections at 6, 24, and 48 hours. Oxidative and nitrosative stress were assayed at 12 hours post-ICH. Injury markers were examined on day 1, and lesion was examined on day 3. Neurologic deficits were examined for 28 days. Progesterone posttreatment reduced lesion volume, brain swelling, edema, and cell degeneration and improved long-term neurologic function. These protective effects were associated with reductions in protein carbonyl formation, protein nitrosylation, and matrix metalloproteinase-9 activity and attenuated cellular and molecular inflammatory responses. Progesterone also reduced vascular endothelial growth factor expression, increased neuronal-specific Na(+)/K(+) ATPase ɑ3 subunit expression, and reduced protein kinase C-dependent Na(+)/K(+) ATPase phosphorylation. Furthermore, progesterone reduced glial scar thickness, myelin loss, brain atrophy, and residual injury volume on day 28 after ICH. With multiple brain targets, progesterone warrants further investigation for its potential use in ICH therapy.

Cerebroprotection of flavanol (-)-epicatechin after traumatic brain injury via Nrf2-dependent and -independent pathways

Traumatic brain injury (TBI), which leads to disability, dysfunction, and even death, is a prominent health problem worldwide with no effective treatment. A brain-permeable flavonoid named (-)-epicatechin (EC) modulates redox/oxidative stress and has been shown to be beneficial for vascular and cognitive function in humans and for ischemic and hemorrhagic stroke in rodents. Here we examined whether EC is able to protect the brain against TBI-induced brain injury in mice and if so, whether it exerts neuroprotection by modulating the NF-E2-related factor (Nrf2) pathway. We used the controlled cortical impact model to mimic TBI. EC was administered orally at 3h after TBI and then every 24h for either 3 or 7 days. We evaluated lesion volume, brain edema, white matter injury, neurologic deficits, cognitive performance and emotion-like behaviors, neutrophil infiltration, reactive oxygen species (ROS), and a variety of injury-related protein markers. Nrf2 knockout mice were used to determine the role of the Nrf2 signaling pathway after EC treatment. In wild-type mice, EC significantly reduced lesion volume, edema, and cell death and improved neurologic function on days 3 and 28; cognitive performance and depression-like behaviors were also improved with EC administration. In addition, EC reduced white matter injury, heme oxygenase-1 expression, and ferric iron deposition after TBI. These changes were accompanied by attenuation of neutrophil infiltration and oxidative insults, reduced activity of matrix metalloproteinase 9, decreased Keap 1 expression, increased Nrf2 nuclear accumulation, and increased expression of superoxide dismutase 1 and quinone 1. However, EC did not significantly reduce lesion volume or improve neurologic deficits in Nrf2 knockout mice after TBI. Our results show that EC protects the TBI brain by activating the Nrf2 pathway, inhibiting heme oxygenase-1 protein expression, and reducing iron deposition. The latter two effects could represent an Nrf2-independent mechanism in this model of TBI.

Progesterone Changes VEGF and BDNF Expression and Promotes Neurogenesis After Ischemic Stroke

Studies have shown that progesterone enhances functional recovery after ischemic stroke, but the underlying mechanisms are not completely understood. Therefore, we investigated the effect of progesterone on vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), and neurogenesis in a rodent stroke model. Rats underwent permanent middle cerebral artery occlusion (pMCAO) and then received intraperitoneal injections of progesterone (15 mg/kg) or vehicle at 1 h followed by subcutaneous injections at 6, 24, and 48 h. We examined VEGF and BDNF expression by Western blotting and/or immunostaining and microvessel density by lectin immunostaining. Neurogenesis in the subventricular zone was determined by immunostaining of Ki67 and doublecortin, and double BrdU/Nestin immunostaining. We calculated brain water content with the wet-dry weight method on day 3 and assessed neurologic deficits with the modified neurological severity score on days 1, 3, 7, and 14. Progesterone-treated rats showed a significant decrease in VEGF expression, but an increase in BDNF expression, compared with that of vehicle-treated pMCAO rats on day 3 post-occlusion. Progesterone did not alter the microvessel density, but it reduced brain water content compared with that in vehicle-treated rats on day 3 post-occlusion. Progesterone treatment increased the numbers of newly generated neurons in the subventricular zone and doublecortin-positive cells in the peri-infarct region on day 7 post-occlusion. In addition, progesterone improved neurologic function on days 7 and 14 post-occlusion. Our data suggest that the enhancement of endogenous BDNF and subsequent neurogenesis could partially underlie the neuroprotective effects of progesterone.

Progesterone Changes VEGF and BDNF Expression and Promotes Neurogenesis After Ischemic Stroke

Studies have shown that progesterone enhances functional recovery after ischemic stroke, but the underlying mechanisms are not completely understood. Therefore, we investigated the effect of progesterone on vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), and neurogenesis in a rodent stroke model. Rats underwent permanent middle cerebral artery occlusion (pMCAO) and then received intraperitoneal injections of progesterone (15 mg/kg) or vehicle at 1 h followed by subcutaneous injections at 6, 24, and 48 h. We examined VEGF and BDNF expression by Western blotting and/or immunostaining and microvessel density by lectin immunostaining. Neurogenesis in the subventricular zone was determined by immunostaining of Ki67 and doublecortin, and double BrdU/Nestin immunostaining. We calculated brain water content with the wet-dry weight method on day 3 and assessed neurologic deficits with the modified neurological severity score on days 1, 3, 7, and 14. Progesterone-treated rats showed a significant decrease in VEGF expression, but an increase in BDNF expression, compared with that of vehicle-treated pMCAO rats on day 3 post-occlusion. Progesterone did not alter the microvessel density, but it reduced brain water content compared with that in vehicle-treated rats on day 3 post-occlusion. Progesterone treatment increased the numbers of newly generated neurons in the subventricular zone and doublecortin-positive cells in the peri-infarct region on day 7 post-occlusion. In addition, progesterone improved neurologic function on days 7 and 14 post-occlusion. Our data suggest that the enhancement of endogenous BDNF and subsequent neurogenesis could partially underlie the neuroprotective effects of progesterone.

GSK-3β inhibitor TWS119 attenuates rtPA-induced hemorrhagic transformation and activates the Wnt/β-catenin signaling pathway after acute ischemic stroke in rats

Hemorrhagic transformation (HT) is a devastating complication for patients with acute ischemic stroke who are treated with tissue plasminogen activator (tPA). It is associated with high morbidity and mortality, but no effective treatments are currently available to reduce HT risk. Therefore, methods to prevent HT are urgently needed. In this study, we used TWS119, an inhibitor of glycogen synthase kinase 3β (GSK-3β), to evaluate the role of the Wnt/β-catenin signaling pathway in recombinant tPA (rtPA)-induced HT. Sprague-Dawley rats were subjected to a middle cerebral artery occlusion (MCAO) model of ischemic stroke and then were administered rtPA, rtPA combined with TWS119, or vehicle at 4 h. The animals were sacrificed 24 h after infarct induction. Rats treated with rtPA showed evident HT, had more severe neurologic deficit, brain edema, and blood-brain barrier breakdown, and had larger infarction volume than did the vehicle group. Rats treated with TWS119 had significantly improved outcomes compared with those of rats treated with rtPA alone. In addition, Western blot analysis showed that TWS119 increased the protein expression of β-catenin, claudin-3, and ZO-1 while suppressing the expression of GSK-3β. These results suggest that TWS119 reduces rtPA-induced HT and attenuates blood-brain barrier disruption, possibly through activation of the Wnt/β-catenin signaling pathway. This study provides a potential therapeutic strategy to prevent tPA-induced HT after acute ischemic stroke.