Blood-Brain Barrier Disruption, Vascular Impairment, and Ischemia/Reperfusion Damage in Diabetic Stroke

The Protective Effects of Dexmedetomidine against Hypoxia/Reoxygenation-Induced Inflammatory Injury and Permeability in Brain Endothelial Cells Mediated by Sigma-1 Receptor

Cerebral ischemia-reperfusion injury (CIRI) mainly arises from the clinical treatment of ischemic stroke, induced by the blood-brain barrier (BBB) disruption and infiltrated inflammation. The Sigma-1 receptor (Sigma-1R) is a novel target for neuroprotection, and the α2-receptor agonist pain medication dexmedetomidine displays a neuroprotective effect through activating Sigma-1R. The present study aims to investigate the potential therapeutic effect of dexmedetomidine in a mouse stroke model and hypoxia/reoxygenation(OGD/R)-induced brain endothelial dysfunction. First, we found that Sigma-1R was significantly upregulated in middle cerebral artery occlusion (MCAO) mice by the administration of dexmedetomidine. In vivo experiments revealed that dexmedetomidine ameliorated hyperpermeability of the blood-brain barrier (BBB), lowered the expression level of Occludin, and impaired brain function as measured by neurological scores in MCAO mice. In vitro assays show that dexmedetomidine alleviated OGD/R-caused cytotoxicity, hyperpermeability, abnormal expression of Occludin, and inflammatory factors in human brain microvascular endothelial cells (HBMVECs). Moreover, blockage of Sigma-1R by its antagonist BD1047 abolished the neuroprotective property of dexmedetomidine in both animal and cell culture experiments. On the basis of these findings, we conclude that dexmedetomidine therapy shows neuroprotection in MCAO mice. Mechanistically, dexmedetomidine alleviated hypoxia/reoxygenation-induced cerebral endothelial dysfunction by activating the Sigma-1R-mediated signaling pathway.

Galectin-3 protects against ischemic stroke by promoting neuro-angiogenesis via apoptosis inhibition and Akt/Caspase regulation

Post-stroke neurological deficits and mortality are often associated with vascular disruption and neuronal apoptosis. Galectin-3 (Gal3) is a potent pro-survival and angiogenic factor. However, little is known about its protective role in the cerebral ischemia/reperfusion (I/R) injury. We have previously shown significant up-regulation of Gal3 in the post-stroke rat brain, and that blocking of Gal3 with neutralizing antibody decreases the cerebral blood vessel density. Our current study demonstrates that intracerebral local delivery of the Gal3 into rat brain at the time of reperfusion exerts neuroprotection. Ischemic lesion volume and neuronal cell death were significantly reduced as compared with the vehicle-treated MCAO rat brains. Gal3 increased vessel density and neuronal survival after I/R in rat brains. Importantly, Gal3-treated groups showed significant improvement in motor and sensory functional recovery. Gal3 increased neuronal cell viability under in vitro oxygen-glucose deprivation conditions in association with increased phosphorylated-Akt, decreased phosphorylated-ERK1/2, and reduced caspase-3 activity. Gene expression analysis showed down regulation of pro-apoptotic and inflammatory genes including Fas-ligand, and upregulation of pro-survival and pro-angiogenic genes including Bcl-2, PECAM, and occludin. These results indicate a key role for Gal3 in neuro-vascular protection and functional recovery following ischemic stroke through modulation of angiogenic and apoptotic pathways.

Tenacissoside H promotes neurological recovery of cerebral ischaemia/reperfusion injury in mice by modulating inflammation and oxidative stress via TrkB pathway

Cerebral ischaemia/reperfusion (I/R)-induced acute brain injury remains a troublesome condition in clinical practice. The present study aimed to investigate the protective effect of tenacissoside H (TH) on I/R-induced cerebral injury in mice. Here, a mouse model of middle cerebral artery occlusion (MCAO) was established by an improved Longa-Zea method. TH was given by intraperitoneal injection once a day within 1 week before establishing the mouse MCAO model. The neurological functions of mice were evaluated and the apoptosis of neurons was also detected by the TUNEL method and Nissl's staining. ELISA and western blot were used to detect the expression of inflammatory factors, oxidation factors and proteins in the cerebral ischaemic cortex. The results revealed that TH dose-dependently reduced neurological impairment, neuron apoptosis and brain oedema induced by MCAO. Furthermore, TH attenuated the expression of pro-inflammatory cytokines (including interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α), iNOS and nuclear factor (NF)-κB while increased production of anti-inflammatory cytokines (IL-4, IL-10 and BDNF) and proteins of tropomyosin-related kinase receptor B (TrkB) and PPARγ. Nevertheless, after the addition of TrkB inhibitor, the effects of TH above were mostly restrained. In conclusion, TH can protect mice against I/R-induced neurological impairments via modulating inflammation and oxidative stress through TrkB signalling.

Melamine exposure from the weaning period causes apoptosis, inflammation, and damage to the blood-brain barrier

The aim of this study to investigate the effects of melamine exposure from the weaning period on the developing brain in rats. Female Wistar albino rats (21 days old, n = 18) were divided into 3 groups, all animals were weighed daily and dose-adjusted. For 3 weeks, 0.1 mL of saline was administered by oral gavage to the control group, 50 mg/kg of melamine to the second group, and 75 mg/kg of melamine to the third group were administered by oral gavage by dissolving in 0.1 mL of saline. On the postnatal 45th day, the rats were sacrificed under anesthesia and brain tissues placed in neutral formalin. After routine tissue processing, brain sections were stained with hematoxylin&eosin(H&E) and Terminal deoxynucleotidyl transferase(TdT) dUTP Nick-End Labeling(TUNEL), IBA-1, Glial Fibrillar Acidic Protein(GFAP), Tumor necrosis factor-α (TNF-α), and SMI-70 antibodies as immunohistochemically. In the results, according to apoptotic index(AI) results, there was a significant increase in the 75 mg/kg and 50 mg/kg melamine groups compared to the control groups (p < 005). There was a significant increase in the number of anti- TNF-α positive neurons and the number of anti-GFAP positive astrocytes in both melamine groups compared to the control group (p < 001). In terms of SMI-71, an increase was found in the 75 mg/kg group compared to other groups (p < 001), while no significant difference was found between the groups in terms of IBA-1 (p > 0.05). It has been observed an increase in dilatation of blood vessels, inflammatory cell infiltration, and endothelial cell degeneration in the 50 mg/kg and 75 mg/kg melamine groups compared to the control group (p < 0.01). there was no statistically significant difference in the body and brain weight between both melamine treatment groups (75 mg/kg and 50 mg/kg) and the control group (p > 005). Melamine exposure (50 mg/kg and 75 mg/kg) from the weaning period causes apoptosis and inflammation in the developing brain, and the disruptions in the blood-brain barrier (BBB) significantly increase exposure to 75 mg/kg.

Impact of aging and comorbidities on ischemic stroke outcomes in preclinical animal models: A translational perspective

Ischemic stroke is a highly complex and devastating neurological disease. The sudden loss of blood flow to a brain region due to an ischemic insult leads to severe damage to that area resulting in the formation of an infarcted tissue, also known as the ischemic core. This is surrounded by the peri-infarct region or penumbra that denotes the functionally impaired but potentially salvageable tissue. Thus, the penumbral tissue is the main target for the development of neuroprotective strategies to minimize the extent of ischemic brain damage by timely therapeutic intervention. Given the limitations of reperfusion therapies with recombinant tissue plasminogen activator or mechanical thrombectomy, there is high enthusiasm to combine reperfusion therapy with neuroprotective strategies to further reduce the progression of ischemic brain injury. Till date, a large number of candidate neuroprotective drugs have been identified as potential therapies based on highly promising results from studies in rodent ischemic stroke models. However, none of these interventions have shown therapeutic benefits in stroke patients in clinical trials. In this review article, we discussed the urgent need to utilize preclinical models of ischemic stroke that more accurately mimic the clinical conditions in stroke patients by incorporating aged animals and animal stroke models with comorbidities. We also outlined the recent findings that highlight the significant differences in stroke outcome between young and aged animals, and how major comorbid conditions such as hypertension, diabetes, obesity and hyperlipidemia dramatically increase the vulnerability of the brain to ischemic damage that eventually results in worse functional outcomes. It is evident from these earlier studies that including animal models of aging and comorbidities during the early stages of drug development could facilitate the identification of neuroprotective strategies with high likelihood of success in stroke clinical trials.

Treatment with an Angiopoietin-1 mimetic peptide promotes neurological recovery after stroke in diabetic rats

Aim

Vasculotide (VT), an angiopoietin‐1 mimetic peptide, exerts neuroprotective effects in type one diabetic (T1DM) rats subjected to ischemic stroke. In this study, we investigated whether delayed VT treatment improves long‐term neurological outcome after stroke in T1DM rats.

Methods

Male Wistar rats were induced with T1DM, subjected to middle cerebral artery occlusion (MCAo) model of stroke, and treated with PBS (control), 2 µg/kg VT, 3 µg/kg VT, or 5.5 µg/kg VT. VT treatment was initiated at 24 h after stroke and administered daily (i.p) for 14 days. We evaluated neurological function, lesion volume, vascular and white matter remodeling, and inflammation in the ischemic brain. In vitro, we evaluated the effects of VT on endothelial cell capillary tube formation and inflammatory responses of primary cortical neurons (PCN) and macrophages.

Results

Treatment of T1DM‐stroke with 3 µg/kg VT but not 2 µg/kg or 5.5 µg/kg significantly improves neurological function and decreases infarct volume and cell death compared to control T1DM‐stroke rats. Thus, 3 µg/kg VT dose was employed in all subsequent in vivo analysis. VT treatment significantly increases axon and myelin density, decreases demyelination, decreases white matter injury, increases number of oligodendrocytes, and increases vascular density in the ischemic border zone of T1DM stroke rats. VT treatment significantly decreases MMP9 expression and decreases the number of M1 macrophages in the ischemic brain of T1DM‐stroke rats. In vitro, VT treatment significantly decreases endothelial cell death and decreases MCP‐1, endothelin‐1, and VEGF expression under high glucose (HG) and ischemic conditions and significantly increases capillary tube formation under HG conditions when compared to non‐treated control group. VT treatment significantly decreases inflammatory factor expression such as MMP9 and MCP‐1 in macrophages subjected to LPS activation and significantly decreases IL‐1β and MMP9 expression in PCN subjected to ischemia under HG conditions.

Conclusion

Delayed VT treatment (24 h after stroke) significantly improves neurological function, promotes vascular and white matter remodeling, and decreases inflammation in the ischemic brain after stroke in T1DM rats.

Neuronal and Cerebrovascular Complications in Coronavirus Disease 2019

Coronavirus disease 2019 (COVID-19) is a pandemic disease resulting from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, primarily in the respiratory tract. This pandemic disease has affected the entire world, and the pathobiology of this disease is not yet completely known. The Interactions of SARS-CoV-2 proteins with different cellular components in the host cell may be necessary for understanding the disease mechanism and identifying crucial pharmacological targets in COVID-19. Studies have suggested that the effect of SARS-CoV-2 on other organs, including the brain, maybe critical for understanding the pathobiology of COVID-19. Symptoms in COVID-19 patients, including impaired consciousness dizziness, headache, loss of taste and smell, vision problems, and neuromuscular pain, suggest that neuronal complications comprise a crucial component of COVID-19 pathobiology. A growing body of literature indicates that SARS-CoV-2 can enter the brain, leading to neuronal defects in COVID-19 patients. Other studies suggest that SARS-CoV-2 may aggravate neuronal complications due to its effects on the cerebrovascular system. Emerging pieces of evidence show that stroke can be one of the leading neurological complications in COVID-19. In this review, we describe the observations about neuronal complications of COVID-19 and how SARS-CoV-2 may invade the brain. We will also discuss the cerebrovascular problems and occurrence of stroke in COVID-19 patients. We will also present the observations and our views about the potential pharmacological strategies and targets in COVID-19. We hope this review will help comprehend the current knowledge of neuronal and cerebrovascular complications from SARS-CoV-2 infections and highlight the possible long-term consequences of SARS-CoV-2 on the human brain.

Coicis semen protects against focal cerebral ischemia-reperfusion injury by inhibiting oxidative stress and promoting angiogenesis via the TGFβ/ALK1/Smad1/5 signaling pathway

Background: Ischemic stroke is a devastating disease that causes long-term disability. However, its pathogenesis is unclear, and treatments for ischemic stroke are limited. Recent studies indicate that oxidative stress is involved in the pathological progression of ischemic stroke and that angiogenesis participates in recovery from ischemic stroke. Furthermore, previous studies have shown that Coicis Semen has antioxidative and anti-inflammatory effects in a variety of diseases. In the present study, we investigated whether Coicis Semen has a protective effect against ischemic stroke and the mechanism of this protective effect.

Results: Coicis Semen administration significantly decreased the infarct volume and mortality and alleviated neurological deficits at 3, 7 and 14 days after MCAO. In addition, cerebral edema at 3 days poststroke was ameliorated by Coicis Semen treatment. DHE staining showed that ROS levels in the vehicle group were increased at 3 days after reperfusion and then gradually declined, but Coicis Semen treatment reduced ROS levels. The levels of GSH and SOD in the brain were increased by Coicis Semen treatment, while MDA levels were reduced. Furthermore, Coicis Semen treatment decreased the extravasation of EB dye in MCAO mouse brains and elevated expression of the tight junction proteins ZO-1 and Occludin. Double immunofluorescence staining and western blot analysis showed that the expression of angiogenesis markers and TGFβ pathway-related proteins was increased by Coicis Semen administration. Consistent with the in vivo results, cytotoxicity assays showed that Coicis Semen substantially promoted HUVEC survival following OGD/RX in vitro. Additionally, though LY2109761 inhibited the activation of TGFβ signaling in OGD/RX model animals, Coicis Semen cotreatment markedly reversed the downregulation of TGFβ pathway-related proteins and increased VEGF levels.

Methods: Adult male wild-type C57BL/6J mice were used to develop a middle cerebral artery occlusion (MCAO) stroke model. Infarct size, neurological deficits and behavior were evaluated on days 3, 7 and 14 after staining. In addition, changes in superoxide dismutase (SOD), GSH and malondialdehyde (MDA) levels were detected with a commercial kit. Blood-brain barrier (BBB) permeability was assessed with Evans blue (EB) dye. Western blotting was also performed to measure the levels of tight junction proteins of the BBB. Additionally, ELISA was performed to measure the level of VEGF in the brain. The colocalization of CD31, angiogenesis markers, and Smad1/5 was assessed by double immunofluorescent staining. TGFβ pathway-related proteins were measured by western blotting. Furthermore, the cell viability of human umbilical vein endothelial cells (HUVECs) following oxygen-glucose deprivation/reoxygenation (OGD/RX) was measured by Cell Counting Kit (CCK)-8 assay.

Conclusions: Coicis Semen treatment alleviates brain damage induced by ischemic stroke through inhibiting oxidative stress and promoting angiogenesis by activating the TGFβ/ALK1 signaling pathway.

Diabetes Mellitus/Poststroke Hyperglycemia: a Detrimental Factor for tPA Thrombolytic Stroke Therapy

Intravenous administration of tissue-type plasminogen activator (IV tPA) therapy has long been considered a mainstay in ischemic stroke management. However, patients respond to IV tPA therapy unequally with some subsets of patients having worsened outcomes after treatment. In particular, diabetes mellitus (DM) is recognized as a clinically important vascular comorbidity that leads to lower recanalization rates and increased risks of hemorrhagic transformation (HT). In this short-review, we summarize the recent advances in understanding of the underlying mechanisms involved in post-IV tPA worsening of outcome in diabetic stroke. Potential pathologic factors that are related to the suboptimal tPA recanalization in diabetic stroke include higher plasma plasminogen activator inhibitor (PAI)-1 level, diabetic atherogenic vascular damage, glycation of the tPA receptor annexin A2, and alterations in fibrin clot density. While factors contributing to the exacerbation of HT in diabetic stroke include hyperglycemia, vascular oxidative stress, and inflammation, tPA neurovascular toxicity and imbalance in extracellular proteolysis are discussed. Besides, impaired collaterals in DM also compromise the efficacy of IV tPA therapy. Additionally, several tPA combination approaches developed from experimental studies that may help to optimize IV tPA therapy are also briefly summarized. In summary, more research efforts are needed to improve the safety and efficacy of IV tPA therapy in ischemic stroke patients with DM/poststroke hyperglycemia.

Advanced glycation end-products disrupt brain microvascular endothelial cell barrier: The role of mitochondria and oxidative stress

During diabetes mellitus, advanced glycation end-products (AGEs) are major contributors to the development of alterations in cerebral capillaries, leading to the disruption of the blood-brain barrier (BBB). Consequently, this is often associated with an amplified oxidative stress response in microvascular endothelial cells. As a model to mimic brain microvasculature, the bEnd.3 endothelial cell line was used to investigate cell barrier function. Cells were exposed to native bovine serum albumin (BSA) or modified BSA (BSA-AGEs). In the presence or absence of the antioxidant compound, N-acetyl-cysteine, cell permeability was assessed by FITC-dextran exclusion, intracellular free radical formation was monitored with H₂DCF-DA probe, and mitochondrial respiratory and redox parameters were analyzed. We report that, in the absence of alterations in cell viability, BSA-AGEs contribute to an increase in endothelial cell barrier permeability and a marked and prolonged oxidative stress response. Decreased mitochondrial oxygen consumption was associated with these alterations and may contribute to reactive oxygen species production. These results suggest the need for further research to explore therapeutic interventions to restore mitochondrial functionality in microvascular endothelial cells to improve brain homeostasis in pathological complications associated with glycation.

Examining the central effects of chronic stressful social isolation on rats

Stress-related disorders are extremely complex and current treatment strategies have limitations. The present study investigated alternative pathological mechanisms using a combination of multiple environmental approaches with biochemical and molecular tools. The aim of the present study was to evaluate blood-brain-barrier (BBB) integrity in socially manipulated animal housing conditions. Multiple environmentally-related models were employed in the current study. The main model proposed (chronically isolated rats) was biochemically validated using the level of peripheral corticosterone. The current study examined and compared the mRNA levels of certain inflammatory and BBB markers in the hippocampal tissue of chronically isolated rats, including claudin-5 (cldn5) and tight junction protein (tjp). Animals were divided into four groups: i) Standard housed rats (controls); ii) chronically isolated rats; iii) control rats treated with fluoxetine, which is a standard selective serotonin reuptake inhibitor; and iv) isolated rats treated with fluoxetine. To further examine the effect of environmental conditions on BBB markers, the current study assessed BBB markers in enriched environmental (EE) housing and short-term isolation conditions. The results demonstrated a significant increase in cldn5 and tjp levels in the chronically isolated group. Despite some anomalous results, alterations in mRNA levels were further confirmed in EE housing conditions compared with chronically isolated rats. This trend was also observed in rats subjected to short-term isolation compared with paired controls. Additionally, levels of IL-6, an inflammatory marker associated with neuroinflammation, were markedly increased in the isolated group. However, treatment with fluoxetine treatment reversed these effects. The results indicated that BBB integrity may be compromised in stress-related disorders, highlighting a need for further functional studies on the kinetics of BBB in stress-related models.

Ability of Post-treatment Glycyrrhizic Acid to Mitigate Cerebral Ischemia/Reperfusion Injury in Diabetic Mice

Background

Diabetes aggravates cerebral ischemia/reperfusion (I/R) injury by increasing inflammatory reactions, but its specific mechanism is currently unclear.

Material/Methods

Diabetes was induced in mice with a high-fat diet combined with streptozotocin. These mice were subjected to transient middle cerebral artery occlusion (tMCAO) for 60 min, followed by reperfusion for 24–72 h and post-treatment glycyrrhizic acid (GA). Control and diabetic mice were randomly allocated to 8 groups of 18 mice each. Blood glucose, brain infarction, brain edema, and neurological function were monitored. Necrosis was determined by Nissl staining, loss of neurons by immunofluorescent (IF) staining for NeuN, and activation of inflammatory microglia by IF staining for Iba-1. Levels of HMGB1, TLR4, Myd88, and NF-κB mRNA and protein in ischemic brain were determined by qRT-PCR and western blotting, respectively, and serum concentrations of IL-1β, IL-6, and TNF-α by ELISA.

Results

Infarction volume, brain edema, and neurological function after tMCAO were significantly aggravated in diabetes, but ameliorated by post-treatment GA. GA also reduced neuronal loss and microglial activation. Cerebral Myd88 level showed a positive correlation with neurological scores. GA suppressed the expression of Myd88 and a proinflammatory pathway that included Myd88, HMGB1, TLR4, and NF-κB, as well as reducing serum concentrations of IL-1β, IL-6, and TNF-α.

Conclusions

Post-treatment inhibited inflammatory responses and provided therapeutic benefits in diabetic mice with cerebral I/R injury, suggesting that GA may be a candidate drug to suppress cerebral I/R in diabetic patients.

Therapeutic Potentials of Extracellular Vesicles for the Treatment of Diabetes and Diabetic Complications

Extracellular vesicles (EVs), including exosomes and microvesicles, are nano-to-micrometer vesicles released from nearly all cellular types. EVs comprise a mixture of bioactive molecules (e.g., mRNAs, miRNAs, lipids, and proteins) that can be transported to the targeted cells/tissues via the blood or lymph circulation. Recently, EVs have received increased attention, owing to their emerging roles in cell-to-cell communication, or as biomarkers with the therapeutic potential to replace cell-based therapy. Diabetes comprises a group of metabolic disorders characterized by hyperglycemia that cause the development of life-threatening complications. The impacts of conventional clinical treatment are generally limited and are followed by many side effects, including hypoglycemia, obesity, and damage to the liver and kidney. Recently, several studies have shown that EVs released by stem cells and immune cells can regulate gene expression in the recipient cells, thus providing a strategy to treat diabetes and its complications. In this review, we summarize the results from currently available studies, demonstrating the therapeutic potentials of EVs in diabetes and diabetic complications. Additionally, we highlight recommendations for future research.

Prefrontal cortex brain damage and glycemic control in patients with type 2 diabetes

BACKGROUND

This study examined brain tissue integrity in sites that controls cognition (prefrontal cortices; PFC) and its relationships to glycemic outcomes in adults with type 2 diabetes mellitus (T2DM).

METHODS

We examined 28 T2DM patients (median age 57.1 years; median body mass index [BMI] 30.6 kg/m² ;11 males) and 47 healthy controls (median age 55.0 years; median BMI 25.8 kg/m² ; 29 males) for cognition (Montreal Cognitive Assessment [MoCA]), glycemic control (hemoglobin A1c [HbA1c]), and PFC tissue status via brain magnetic resonance imaging (MRI). High-resolution T1-weighted images were collected using a 3.0-Tesla MRI scanner, and PFC tissue changes (tissue density) were examined with voxel-based morphometry procedures.

RESULTS

Reduced PFC density values were observed in T2DM patients compared to controls (left, 0.41 ± 0.02 mm³ /voxel vs 0.44 ± 0.02 mm³ /voxel, P < 0.001; right, 0.41 ± 0.03 mm³ /voxel vs 0.45 ± 0.02 mm³ /voxel, P < 0.001). PFC density values were positively correlated with cognition; left PFC region (r = 0.53, P = 0.005) and right PFC region (r = 0.56, P = 0.003), with age and sex as covariates. Significant negative correlations were found between PFC densities and HbA1c values; left PFC region (r = -0.39, P = 0.049) and right PFC region (r = -0.48, P = 0.01), with age and sex as covariates.

CONCLUSIONS

T2DM patients showed PFC brain tissue damage, which is associated with cognitive deficits and poor glycemic control. Further research is needed to identify causal relationships between HbA1c, cognition, and brain changes in T2DM and to evaluate the impact of interventions to prevent brain tissue injury or neuroregeneration in this high-risk patient population, to eventually preserve or enhance cognition and improve glucose outcomes.

Immune-Inflammatory, Metabolic, Oxidative, and Nitrosative Stress Biomarkers Predict Acute Ischemic Stroke and Short-Term Outcome

Immune-inflammatory, metabolic, oxidative, and nitrosative stress (IMO&NS) pathways and, consequently, neurotoxicity are involved in acute ischemic stroke (IS). The simultaneous assessment of multiple IMO&NS biomarkers may be useful to predict IS and its prognosis. The aim of this study was to identify the IMO&NS biomarkers, which predict short-term IS outcome. The study included 176 IS patients and 176 healthy controls. Modified Rankin scale (mRS) was applied within 8 h after IS (baseline) and 3 months later (endpoint). Blood samples were obtained within 24 h after hospital admission. IS was associated with increased white blood cell (WBC) counts, high sensitivity C-reactive protein (hsCRP), interleukin (IL-6), lipid hydroperoxides (LOOHs), nitric oxide metabolites (NOx), homocysteine, ferritin, erythrocyte sedimentation rate (ESR), glucose, insulin, and lowered iron, 25-hydroxyvitamin D [25(OH)D], total cholesterol, and high-density lipoprotein (HDL) cholesterol. We found that 89.4% of the IS patients may be correctly classified using the cumulative effects of male sex, systolic blood pressure (SBP), glucose, NOx, LOOH, 25(OH)D, IL-6, and WBC with sensitivity of 86.2% and specificity of 93.0%. Moreover, increased baseline disability (mRS ≥ 3) was associated with increased ferritin, IL-6, hsCRP, WBC, ESR, and glucose. We found that 25.0% of the variance in the 3-month endpoint (mRS) was explained by the regression on glucose, ESR, age (all positively), and HDL-cholesterol, and 25(OH)D (both negatively). These results show that the cumulative effects of IMO&NS biomarkers are associated with IS and predict a poor outcome at 3-month follow-up.

Endogenous Regulatory T Cells Promote M2 Macrophage Phenotype in Diabetic Stroke as Visualized by Optical Imaging

Regulatory T cells (Tregs) play an immunosuppressive role in various diseases, yet their function remains controversial in stroke and obscure in diabetic stroke. In the present study, Tregs were found downregulated in the peripheral blood of type 2 diabetes mellitus (T2DM) stroke models and patients compared with controls. In ischemic stroke mice (both T2DM and wild type), endogenous Tregs boosted by CD28SA increased CD206+ M2 macrophage/microglia cells, decreased infarct volumes, and improved neurological recovery. Our results demonstrated the potential of boosting Tregs for treating T2DM stroke. Furthermore, we utilized an optical imaging probe (IRD-αCD206) to target M2 macrophage/microglia cells and demonstrated its effect in visualizing M2 macrophage/microglia cells in vivo in ischemic brain tissue.

Curcumin attenuates cytoplasmic/endoplasmic reticulum stress, apoptosis and cholinergic dysfunction in diabetic rat hippocampus

Diabetes mellitus (DM) is associated with the increased risk of the central nervous system complications as cerebrovascular disease, impaired cognition, dementia and neurodegeneration. Curcumin is a polyphenol with anti-oxidant, anti-inflammatory, anti-hyperlipidemic, and anti-cancer effects. Therefore, the present study was aimed to focus on the mechanistic insights of diabetes-induced hippocampal neurodegeneration in addition to shedding the light on the modulatory effect of curcumin. Twenty-eight male Wistar rats were randomly divided into four groups. Type I DM was induced by a single intra-peritoneal injection of streptozotocin (STZ) (65 mg/kg b.w.). Curcumin (100 mg/kg b.w.) was given to the diabetic group after the induction and for eight weeks. Hippocampal glucose-regulated protein 78 (GRP78), activating transcription factor 4 (ATF-4), Bcl2 and choline acetyl transferase (ChAT) genes expression were assessed. Heat shock protein 70 (HSP70), Bcl-2-Associated X protein (Bax), Interferon-γ (INF-γ) and CCAAT-enhancer-binding protein homologous protein (CHOP) levels in the hippocampus were immunoassayed, in addition to the assessment of glycemic and redox status. Curcumin significantly improved blood glucose level, redox status, cellular stress, and decreased INF-γ and Bax levels, down-regulated GRP78 and ATF-4 expression, meanwhile, up-regulated Bcl2 and ChAT expression in hippocampus. Histological findings proved the biochemical and molecular findings. Our results support curcumin as a potential neuro-protective agent against diabetes induced hippocampal neurodegeneration.

Ebselen reversed peripheral oxidative stress induced by a mouse model of sporadic Alzheimer's disease

Intracerebroventricular streptozotocin injection (icv STZ) is a well established sporadic Alzheimer's disease (AD) model in rodents. AD is characterized by neuronal degeneration accompanied by central oxidative stress. Studies also indicate peripheral oxidative damage in AD, but if the icv STZ model of sporadic AD mimics this feature is an open question. This study aimed to investigate if icv STZ administration induces peripheral oxidative stress and the antioxidant action of Ebselen, compared to the reference drug (donepezil), in this sporadic AD model. Male adult Swiss mice received icv STZ (days 1 and 3). Mice received Ebselen (10 mg/kg, i.p) or Donepezil (5 mg/kg, i.p) for 14 days. Mice were killed and the kidney and liver were excised to determine parameters of oxidative stress and toxicity markers. The mice icv STZ-injected showed peripheral oxidative stress. Ebselen reversed renal lipid peroxidation in the icv STZ administered mice by modulating NPSH levels, SOD and CAT activities, whereas Donepezil, modulated only NPSH levels. Ebselen and Donepezil counteracted hepatic lipid peroxidation in STZ-injected mice by modulating NPSH levels and CAT activity. The δ-ALA-D activity was inhibited in the kidney, but not in the liver, whereas the icv STZ-injected mice had an increase in the GST activity in both tissues. Ebselen reversed the increase in the hepatic GST activity of the STZ-injected mice. Donepezil increased renal GST activity in the control mice. In conclusion, this study demonstrates that the icv STZ administration induced peripheral oxidative stress. Ebselen, similar to Donepezil, was effective against peripheral oxidative stress in a mouse model of sporadic AD.

CLEC14A deficiency exacerbates neuronal loss by increasing blood-brain barrier permeability and inflammation

Background

Ischemic stroke is a main cause of mortality. Blood-brain barrier (BBB) breakdown appears to play a critical role in inflammation in patients with ischemic stroke and acceleration of brain injury. The BBB has a protective function and is composed of endothelial cells, pericytes, and astrocytes. In ischemic stroke treatments, regulation of vascular endothelial growth factor (VEGF)-A and vascular endothelial growth factor receptor (VEGFR)-2 is a crucial target despite adverse effects. Our previous study found that loss of C-type lectin family 14 member A (CLEC14A) activated VEGF-A/VEGFR-2 signaling in developmental and tumoral angiogenesis. Here, we evaluate the effects of BBB impairment caused by CLEC14A deficiency in ischemia-reperfusion injury.

Methods

In vitro fluorescein isothiocyanate (FITC)-dextran permeability, transendothelial electrical resistance (TEER) assay, and immunostaining were used to evaluate endothelial integrity. BBB permeability was assessed using Evans blue dye and FITC-dextran injection in Clec14a^−/− (CLEC14A-KO) mice and wild-type mice. Middle cerebral artery occlusion surgery and behavioral assessments were performed to evaluate the neurologic damage. The change of tight junctional proteins, adhesion molecules, pro-inflammatory cytokines, and microglial were confirmed by immunofluorescence staining, Western blotting, and quantitative reverse transcription polymerase chain reaction of brain samples.

Results

In endothelial cells, knockdown of CLEC14A increased FITC-dextran permeability and decreased transendothelial electrical resistance; the severity of this effect increased with VEGF treatment. Immunofluorescence staining revealed that tight junctional proteins were attenuated in the CLEC14A knockdown endothelial cells. Consistent with the in vitro results, CLEC14A-KO mice that were injected with Evans blue dye had cerebral vascular leakage at postnatal day 8; wild-type mice had no leakage. We used a middle cerebral artery occlusion model and found that CLEC14A-KO mice had severe infarcted brain and neurological deficits with upregulated VEGFR-2 expression. FITC-dextran leakage was present in CLEC14A-KO mice after ischemia-reperfusion, and the numbers of tight junctional molecules were significantly decreased. Loss of CLEC14A increased the pro-inflammatory response through adhesion molecule expression, and glial cells were activated.

Conclusions

These results suggest that activation of VEGFR-2 in CLEC14A-KO mice aggravates ischemic stroke by exacerbating cerebral vascular leakage and increasing neuronal inflammation after ischemia-reperfusion injury.

Spatiotemporal Distribution of Agrin after Intrathecal Injection and Its Protective Role in Cerebral Ischemia/Reperfusion Injury

Intrathecal injection, drugs transporting along perivascular spaces, represents an important route for maintaining blood-brain barrier (BBB) integrity after cerebral ischemia/reperfusion (I/R) injury. However, after being directly injected into cerebrospinal fluid (CSF), the temporal and spatial changes in the distribution of therapeutic protein drugs have remained unknown. Here, with positron emission tomography (PET) imaging, the uptake of 89Zr-agrin is noninvasively and dynamically monitored. These data demonstrate the time-activity curve of drugs in the brain subregions and their spatial distribution in different organs after intrathecal administration. Furthermore, agrin treatment effectively inhibits BBB disruption by reducing the loss of tight-junctional proteins. Importantly, the infarct volume is reduced; the number of apoptotic neurons is decreased; and neurological function is improved in mouse I/R injury models. Thus, intrathecal injection of agrin provides the basis for a new strategy to research and develop protein drugs for reducing the aggravation of I/R injury.

Transient versus Permanent MCA Occlusion in Mice Genetically Modified to Have Good versus Poor Collaterals

Collateral-dependent blood flow is capable of significantly lessening the severity of stroke. Unfortunately, collateral flow varies widely in patients for reasons that remain unclear. Studies in mice have shown that the number and diameter of cerebral collaterals vary widely due primarily to polymorphisms in genes, e.g., Rabep2, involved in their formation during development. However, understanding how variation in collateral abundance affects stroke progression has been hampered by lack of a method to reversibly ligate the distal middle cerebral artery (MCAO) in mice. Here we present a method and examine infarct volume 24 h after transient (tMCAO, 90 min) versus permanent occlusion (pMCAO) in mice with good versus poor collaterals. Wildtype C57BL/6 mice (have abundant collaterals) sustained small infarctions following tMCAO that increased 2.1-fold after pMCAO, reflecting significant penumbra present at 90 min. Mutant C57BL/6 mice lacking Rabep2 (have reduced collaterals) sustained a 4-fold increase in infarct volume over WT following tMCAO and a smaller additional increase (0.4-fold) after pMCAO, reflecting reduced penumbra. Wildtype BALB/cBy (have a deficient Rabep2 variant and poor collaterals) had large infarctions following tMCAO that increased less (0.6-fold) than the above wildtype C57BL/6 mice following pMCAO. Mutant BALB/cBy mice (have deficient Rabep2 replaced with the C57BL/6 variant thus increased collaterals) sustained smaller infarctions after tMCAO. However, unlike C57BL/6 versus Rabep2 mice, penumbra was not increased since infarct volume increased only 0.3-fold following pMCAO. These findings present a murine model of tMCAO and demonstrate that neuroprotective mechanisms, in addition to collaterals, also vary with genetic background and affect the evolution of stroke.

Amyloid β deposition in subcortical stroke patients and effects of educational achievement: A pilot study

OBJECTIVE

A direct causal relationship of cerebrovascular risk factors/stroke to amyloid β (Aβ) deposition has yet to be shown. We conducted [¹¹ C] Pittsburgh compound B (PiB)-positron emission tomography (PET) analysis on subacute ischemic stroke patients and healthy controls. We hypothesized that subacute ischemic stroke patients would show focal Aβ accumulation in cortical regions, which would increase and extend over time during the chronic phase after stroke onset.

METHODS

Patients were recruited 14 to 28 days after acute subcortical ischemic stroke and examined with [¹¹ C]PiB-PET scans. Regional time-activity data were analyzed with the Logan graphical method. Whole brain voxel-based analysis was conducted to compare stroke patients with healthy controls. We also performed longitudinal comparison of patients with successive [¹¹ C]PiB-PET scans 1 year after stroke.

RESULTS

Voxel-based analysis revealed a significant increase of [¹¹ C]PiB-BP_ND of the precuneus/posterior cingulate cortex (PCu/PCC) in stroke patients at the subacute stage. Based on stepwise multiple regression analysis of [¹¹ C]PiB-BP changes during follow-up as the dependent variable, years of education was the best independent correlate. There was a significant negative relationship between changes in [¹¹ C]PiB-BP and years of education.

CONCLUSIONS

Our results suggest that processes before and after the onset of ischemic stroke may trigger Aβ deposition in the PCu/PCC, whereby amyloid deposition begins at an early stage of Alzheimer's disease (AD). Our findings support the existence of a cooperative association between vascular risk factors/stroke and AD progression. Further, educational achievement had a protective effect against the increase in Aβ accumulation.

Angiopoietin-Tie Signaling Pathway in Endothelial Cells: A Computational Model

The angiopoietin-Tie signaling pathway is an important vascular signaling pathway involved in angiogenesis, vascular stability, and quiescence. Dysregulation in the pathway is linked to the impairments in vascular function associated with many diseases, including cancer, ocular diseases, systemic inflammation, and cardiovascular diseases. The present study uses a computational signaling pathway model validated against experimental data to quantitatively study various mechanistic aspects of the angiopoietin-Tie signaling pathway, including receptor activation, trafficking, turnover, and molecular mechanisms of its regulation. The model provides mechanistic insights into the controversial role of Ang2 and its regulators vascular endothelial protein tyrosine phosphatase (VE-PTP) and Tie1 and predicts synergistic effects of inhibition of VE-PTP, Tie1, and Tie2 cleavage on enhancing the vascular protective actions of Tie2.

Efficacy and Safety of NaoShuanTong Capsule in the Treatment of Ischemic Stroke: A Meta-Analysis

Background: Ischemic stroke (IS) is a leading cause of death and long-term disability worldwide. The NaoShuanTong capsule (NSTC), a traditional Chinese patent medicine, has been extensively used in the treatment of stroke in China. However, the clinical efficacy and safety of this treatment has not been statistically and systematically verified by any comprehensive pooled analysis. We therefore performed a meta-analysis to evaluate the efficacy and safety of NSTC in the treatment of IS.

Methods: Randomized controlled trials (RCTs) of NSTC in the treatment of IS conducted before September 2018 were retrieved from five databases, according to specific inclusion and exclusion criteria. Two investigators independently reviewed the included studies and extracted relevant data. The methodological quality of the included studies was assessed using criteria from the Cochrane Handbook, and analyzed using Review Manager 5.3 software.

Results: Thirteen RCTs comprising a total of 1,360 participants were included in this study. NSTC was shown to significantly improve the overall response rate (OR = 3.04, 95% CI [1.76, 5.26], P < 0.00001), and neurological function (NSTC increased Modified Barthel Index (MD = 8.15, 95% CI [3.79, 12.52], P = 0.0005), Functional Independence Measure (MD = 29.61, 95% CI [10.11, 49.10], P = 0.003) and European Stroke Scale scores (MD = 8.51, 95% CI [7.00, 10.01], P = 0.03). In addition, NSTC significantly increased serum adiponectin level (MD = 0.66, 95% CI [0.23, 1.08], P = 0.002). Moreover, NSTC reduced atherosclerotic plaque area (MD = -2.24, 95% CI [-4.02, -0.46], P = 0.01) and intima-media thickness (MD = -0.09, 95% CI [-0.13, -0.05], P < 0.0001). However, there was no significant difference between NSTC treatment and conventional therapy with respect to Fugl-Meyer Assessment score (MD = 10.59, 95% CI [-1.78, 22.96], P = 0.09) or Crouse score (MD = -0.78, 95% CI [-1.79, -0.22], P = 0.13).

Conclusions: The results of this meta-analysis showed that NSTC exhibits efficacy in the treatment of cerebral infarction. NSTC can improve the overall response rate and neurological function, increase blood adiponectin, reduce neurological deficits, and decrease atherosclerotic plaque area.

Biomarkers for ischemic stroke subtypes: A protein-protein interaction analysis

According to the Trial of Org 10172 in Acute Stroke Treatment, ischemic stroke is classified into five subtypes. However, the predictive biomarkers of ischemic stroke subtypes are still largely unknown. The utmost objective of this study is to map, construct and analyze protein-protein interaction (PPI) networks for all subtypes of ischemic stroke, and to suggest the predominant biological pathways for each subtypes. Through 6285 protein data retrieved from PolySearch2 and STRING database, the first PPI networks for all subtypes of ischemic stroke were constructed. Notably, F2 and PLG were identified as the critical proteins for large artery atherosclerosis (LAA), lacunar, cardioembolic, stroke of other determined etiology (SOE) and stroke of undetermined etiology (SUE). Gene ontology and DAVID analysis revealed that GO:0030193 regulation of blood coagulation and GO:0051917 regulation of fibrinolysis were the important functional clusters for all the subtypes. In addition, inflammatory pathway was the key etiology for LAA and lacunar, while FOS and JAK2/STAT3 signaling pathways might contribute to cardioembolic stroke. Due to many risk factors associated with SOE and SUE, the precise etiology for these two subtypes remained to be concluded.

Intravenous delivery of adipose tissue-derived mesenchymal stem cells improves brain repair in hyperglycemic stroke rats

Background

Over 50% of acute stroke patients have hyperglycemia, which is associated with a poorer prognosis and outcome. Our aim was to investigate the impact of hyperglycemia on behavioral recovery and brain repair of delivered human adipose tissue-derived mesenchymal stem cells (hAD-MSCs) in a rat model of permanent middle cerebral artery occlusion (pMCAO).

Methods

Hyperglycemia was induced in rats by the administration of nicotinamide and streptozotocin. The rats were then subjected to stroke by a pMCAO model. At 48 h post-stroke, 1 × 10⁶ hAD-MSCs or saline were intravenously administered. We evaluated behavioral outcome, infarct size by MRI, and brain plasticity markers by immunohistochemistry (glial fibrillary acidic protein [GFAP], Iba-1, synaptophysin, doublecortin, CD-31, collagen-IV, and α-smooth muscle actin [α-SMA]).

Results

The hyperglycemic group exhibited more severe neurological deficits; lesion size and diffusion coefficient were larger compared with the non-hyperglycemic rats. GFAP, Iba-1, and α-SMA were increased in the hyperglycemic group. The hyperglycemic rats administered hAD-MSCs at 48 h after pMCAO had improved neurological impairment. Although T2-MRI did not show differences in lesion size between groups, the rADC values were lower in the treated group. Finally, the levels of GFAP, Iba-1, and arterial wall thickness were lower in the treated hyperglycemic group than in the nontreated hyperglycemic group at 6 weeks post-stroke.

Conclusions

Our data suggest that rats with hyperglycemic ischemic stroke exhibit increased lesion size and impaired brain repair processes, which lead to impairments in behavioral recovery after pMCAO. More importantly, hAD-MSC administration induced better anatomical tissue preservation, associated with a good behavioral outcome.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1322-x) contains supplementary material, which is available to authorized users.

Cardiovascular factors moderate the association of infection burden with cognitive function in young to middle-aged U.S. adults

BACKGROUND

Infectious diseases might affect cognitive aging and dementia risk, possibly via neuroinflammation. Similarly, risk factors for cardiovascular and cerebrovascular diseases are associated with cognitive function and dementia. We hypothesized that cardiovascular risk factors moderate the association of exposure to infectious diseases with cognitive function.

METHODS

We studied 5662 participants aged 20 to 59 years from the third National Health and Nutrition Examination Survey (1988-1994) in the United States. We used linear regression to investigate whether the Framingham general cardiovascular risk index moderated the association of infection burden based on exposure to eight different infectious diseases with cognitive functioning as measured by the Symbol Digit Substitution, Serial Digit Learning, and Reaction Time tests.

RESULTS

The multiplicative interaction between the infection-burden index and the cardiovascular-risk index was associated with performance on the Symbol Digit Substitution (B = .019 [95% CI: .008, .031], p < .001) but not on the Serial Digit Learning (B = .034 [95% CI: -.025, .094]) or for Reaction Time (B = -.030 [95% CI: -.848, .787]). Participants with a lower cardiovascular risk appeared to be more resilient against the potential adverse effects of higher infection burden on the Symbol Digit Substitution task.

CONCLUSIONS

Participants at zero risk for a cardiovascular event in the next 10 years had no differences in processing speed with increasing exposure to infectious disease, whereas participants with higher risk for a cardiovascular event had worse processing speed with increased exposure to infectious disease.

Zinc accumulation in mitochondria promotes ischemia-induced BBB disruption through Drp1-dependent mitochondria fission

High concentration of zinc has been reported to act as a critical mediator of neuronal death in the ischemic brain. Our previous studies showed that labile zinc accumulates in cerebromicrovessels and contributes to blood-brain barrier (BBB) permeability increase after cerebral ischemia. However, the role of mitochondrial zinc in ischemia-induced BBB permeability alteration is still unclear. In this study, we showed that ischemia/reperfusion induced free zinc accumulation in endothelial cells (ECs), resulting in increased generation of reactive oxygen species (ROS) in both cultured ECs and in microvessels isolated from the brain of ischemic rats. Furthermore, we found that zinc was highly accumulated in mitochondria, leading to mitochondrial ROS generation under the ischemic condition. Moreover, zinc overload in mitochondria resulted in the collapse of the network of mitochondria, which was mediated through Dynamin-related protein-1 (Drp-1) dependent mitochondrial fission pathway. Finally, the zinc overload in mitochondria activated matrix metalloproteinase-2 and led to ischemia-induced BBB permeability increase. This study demonstrated that zinc-ROS pathway in mitochondria contributes to the ischemia-induced BBB disruption via Drp-1 dependent mitochondrial fission pathway.

Intrinsic Effects of Gold Nanoparticles on Oxygen-Glucose Deprivation/Reperfusion Injury in Rat Cortical Neurons

This study aimed to investigate the potential effects of gold nanoparticles (Au-NPs) on rat cortical neurons exposed to oxygen-glucose deprivation/reperfusion (OGD/R) and to elucidate the corresponding mechanisms. Primary rat cortical neurons were exposed to OGD/R, which is commonly used in vitro to mimic ischemic injury, and then treated with 5- or 20-nm Au-NPs. We then evaluated cell viability, apoptosis, oxidative stress, and mitochondrial respiration in these neurons. We found that 20-nm Au-NPs increased cell viability, alleviated neuronal apoptosis and oxidative stress, and improved mitochondrial respiration after OGD/R injury, while opposite effects were observed for 5-nm Au-NPs. In terms of the underlying mechanisms, we found that Au-NPs could regulate Akt signaling. Taken together, these results show that 20-nm Au-NPs can protect primary cortical neurons against OGD/R injury, possibly by decreasing apoptosis and oxidative stress, while activating Akt signaling and mitochondrial pathways. Our results suggest that Au-NPs may be potential therapeutic agents for ischemic stroke.

Mild hypothermia alleviates diabetes aggravated cerebral ischemic injury via activating autophagy and inhibiting pyroptosis

Diabetic patients manifest with more severe neurological deficits than non-diabetes after ischemic stroke. It has been shown that hypothermia has neuroprotective effects on cerebral ischemia, but whether it is effective for cerebral ischemia in diabetic patients remains unknown. The aim of this study was to investigate whether hypothermia can alleviate cerebral ischemic injury in diabetic rats and the regulation of autophagy and pyroptosis of the treatment. We introduced permanent middle cerebral artery occlusion (pMCAO) in a model of type 2 diabetic rats prepared by high-fat diet combined with intraperitoneal injection of STZ in vivo and mimicked cerebral ischemia with diabetes by employing high glucose stimulation and oxygen-glucose deprivation/reoxygenation (OGD/R) in vitro. Moreover, 3-methyladenine and bafilomycin A1 were used to evaluate the association between autophagy and pyroptosis in vitro. Our results showed that diabetes aggravated neurological deficits, increased the volume of cerebral infarction and brain edema as well as the blood brain barrier permeability after cerebral ischemia, which were alleviated by mild hypothermia. Compared with the pMCAO model in non-diabetic rats and OGD/R model without high glucose stimulation in vitro, the expression of P62, NOD-like receptor protein 3 (NLRP3), cleaved caspase-1 and Gasdermin-N increased and the ratio of microtubule-associated protein 1 light chain 3B (LC3B) Ⅱ/Ⅰ decreased in the pMCAO model in diabetic rats and OGD/R model with high glucose stimulation, which could be reversed by mild hypothermia. In conclusion, mild hypothermia alleviated diabetes aggravated cerebral ischemic injury via activating autophagy and inhibiting pyroptosis.

Targeting the HIV-infected brain to improve ischemic stroke outcome

HIV-associated cerebrovascular events remain highly prevalent even in the current era of antiretroviral therapy (ART). We hypothesize that low-level HIV replication and associated inflammation endure despite antiretroviral treatment and affect ischemic stroke severity and outcomes. Using the EcoHIV infection model and the middle cerebral artery occlusion as the ischemic stroke model in mice, we present in vivo analysis of the relationship between HIV and stroke outcome. EcoHIV infection increases infarct size and negatively impacts tissue and functional recovery. Ischemic stroke also results in an increase in EcoHIV presence in the affected regions, suggesting post-stroke reactivation that magnifies pro-inflammatory status. Importantly, ART with a high CNS penetration effectiveness (CPE) is more beneficial than low CPE treatment in limiting tissue injury and accelerating post-stroke recovery. These results provide potential insight for treatment of HIV-infected patients that are at risk of developing cerebrovascular disease, such as ischemic stroke.

Autoimmunity in acute ischemic stroke and the role of blood-brain barrier: the dark side or the light one?

This article presents a synopsis of the current data on the mechanisms of blood-brain barrier (BBB) alteration and autoimmune response in acute ischemic stroke. Most researchers confirm the relationship between the severity of immunobiochemical changes and clinical outcome of acute ischemic stroke. Ischemic stroke is accompanied by aseptic inflammation, which alters the brain tissue and exposes the co-stimulatory molecules of the immune system and the neuronal antigens. To date, BBB is not considered the border between the immune system and central nervous system, and the local immune subsystems are found within and behind the BBB. BBB disruption contributes to the leakage of brain autoantigens and induction of secondary autoimmune response to neuronal antigens and long-term inflammation. Glymphatic system function is altered and jeopardized both in hemorrhagic and ischemic stroke types. The receptors of innate immunity (toll-like receptor-2 and toll-like receptor-4) are also involved in acute ischemia-reperfusion injury. Immune response is related to the key processes of blood clotting and fibrinolysis. At the same time, the stroke-induced immune activation may promote reparation phenomena in the brain. Subsequent research on the reduction of the acute ischemic brain injury through the target regulation of the immune response is promising.

Vitexin protects against ischemia/reperfusion-induced brain endothelial permeability

Brain endothelial permeability plays a crucial role in blood-brain barrier (BBB), but the permeability enhancement in cerebral ischemia reperfusion (I/R). Vitexin has certain neuroprotective effects, but the effect brain endothelial permeability in I/R injury was unknown. In this study, the effects of Vitexin on endothelial permeability and the underlying mechanisms in human brain microvascular endothelial cells (HBMEc) I/R injury model were investigated. Cell viability, lactate dehydrogenase (LDH), inflammation and apoptosis were detected. The effects of Vitexin on BBB integrity tight junction, matrix metalloproteinases (MMP) were also investigated. The mechanism was confirmed by PI3K inhibitor and NOS inhibitor in normal or eNOS siRNA transfection HBMEc. Vitexin significantly reduced LDH, Caspase 3 level, alleviated inflammation, also could maintain BBB integrity, increased tight junction proteins expression and inhibited MMP. The mechanism is related to reduction of intracellular NO and ONOO^-, regulated eNOS, iNOS activity. Vitexin significantly preserved eNOS phosphorylation in response to the activated Akt. Moreover, combined with PI3K inhibitor or low dosage of NOS inhibitor, totally abolished Vitexin-induced eNOS phosphorylation, the protected effect was also attenuated, but still significantly between model cells. However, combined with high dosage NOS inhibitor which both inhibited the eNOS phosphorylation and iNOS, the protected effect of Vitexin was abrogated. In addition, eNOS silencing cells were used to further clarify the regulatory role of Vitexin on iNOS. Our findings showed that Vitexin could play a protective role in I/R-induced brain endothelial permeability by simultaneously increase eNOS phosphorylation and inhibit iNOS.

1, 25-D3 Protects From Cerebral Ischemia by Maintaining BBB Permeability via PPAR-γ Activation

The blood-brain barrier (BBB) is a physical and biochemical barrier that maintains cerebral homeostasis. BBB dysfunction in an ischemic stroke, results in brain injury and subsequent neurological impairment. The aim of this study was to determine the possible protective effects of 1, 25-dihydroxyvitamin D3 [1, 25(OH)2D3, 1, 25-D3, vit D] on BBB dysfunction, at the early stages of an acute ischemic brain injury. We analyzed the effects of 1, 25-D3 on BBB integrity in terms of histopathological changes, the neurological deficit, infarct size and the expression of brain derived neurotrophic factor (BDNF), in a middle cerebral artery occlusion/reperfusion (MCAO/R) rat model. BBB permeability and the expression of permeability-related proteins in the brain were also evaluated by Evans blue (EB) staining and Western blotting respectively. To determine the possible mechanism underlying the role of 1, 25-D3 in BBB maintenance, after MCAO/R, the rats were treated with the specific peroxisome proliferator-activated receptor gamma (PPARγ) inhibitor GW9662. Supplementation with 1, 25-D3 markedly improved the neurological scores of the rats, decreased the infarct volume, prevented neuronal deformation and upregulated the expression of the tight junction (TJ) and BDNF proteins in their brains. Furthermore, it activated PPARγ but downregulated neuro-inflammatory cytokines such as nuclear factor kappa-B (NF-κB) and tumor necrosis factor-α (TNF-α), after MCAO/R. Taken together, 1, 25-D3 protects against cerebral ischemia by maintaining BBB permeability, upregulating the level of BDNF and inhibiting PPARγ-mediated neuro-inflammation.

Exosome-mediated amplification of endogenous brain repair mechanisms and brain and systemic organ interaction in modulating neurological outcome after stroke

Ischemic stroke is caused by a regional interruption of cerebral blood flow to the brain. Rigorous pre-clinical and clinical research has made landmark progress in stroke treatment using thrombolytics and endovascular thrombectomy. Although numerous successful neuroprotective therapeutic agents for ischemic stroke have been reported in pre-clinical studies, most of them failed in clinical testing. Persistent pre-clinical research has demonstrated that the ischemic brain is not only passively dying but is also actively recovering. Within the neurovascular niche in the peri-infarct tissue, repair mechanisms thrive on the interactions between the neural and vascular compartments. In this review, we discuss exogenous therapy using mesenchymal stromal cell-derived exosomes to amplify endogenous brain repair mechanisms and to induce neurorestorative effects after stroke. Emerging evidence indicates that multiple communication axes between the various organs such as the brain, heart, kidney and gut, and whole body immune response mediated by the spleen can also affect stroke outcome. Therefore, in this review, we summarize this evidence and initiate a discussion on the potential to improve stroke outcome by amplifying multiple brain repair mechanisms after stroke, and by targeting peripheral organs and downstream events to enhance recovery in the injured brain and promote over all well being.

Angiopoietin-1 Mimetic Peptide Promotes Neuroprotection after Stroke in Type 1 Diabetic Rats

Angiopoietin-1 (Ang1) mediates vascular maturation and immune response. Diabetes decreases Ang1 expression and disrupts Ang1/Tie2 signaling activity. Vasculotide is an Ang1 mimetic peptide, and has anti-inflammatory effects. In this study, we test the hypothesis that vasculotide treatment induces neuroprotection and decreases inflammation after stroke in type 1 diabetic (T1DM) rats. T1DM rats were subjected to embolic middle cerebral artery occlusion (MCAo) and treated with: 1) phosphate buffered saline (PBS); 2) vasculotide (3µg/kg, i.p. injection) administered half an hour prior to MCAo and at 8 and 24 hours after MCAo. Rats were sacrificed at 48 h after MCAo. Neurological function, infarct volume, hemorrhage, blood brain barrier (BBB) permeability and neuroinflammation were measured. Vasculotide treatment of T1DM-MCAo rats significantly improves functional outcome, decreases infarct volume and BBB permeability, but does not decrease brain hemorrhagic transformation compared with PBS-treated T1DM-MCAo rats. In the ischemic brain, Vasculotide treatment significantly decreases apoptosis, number of cleaved-caspase-3 positive cells, the expression of monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor (TNF-α). Western blot analysis shows that vasculotide significantly decreases expression of receptor for advanced glycation end products (RAGE), MCP-1 and TNF-α in the ischemic brain compared with T1DM-MCAo rats. Vasculotide treatment in cultured primary cortical neurons (PCN) significantly decreases TLR4 expression compared with control. Decreased neuroinflammation and reduced BBB leakage may contribute, at least in part, to vasculotide-induced neuroprotective effects after stroke in T1DM rats.

Vitamin D deficiency increases blood-brain barrier dysfunction after ischemic stroke in male rats

Because vitamin D hormone deficiency (VDH^def) can worsen severity and outcome for ischemic stroke, we examined the role of VDH in maintaining blood-brain-barrier (BBB integrity) in a rat model of stroke. In most types of stroke, the BBB is markedly compromised, potentially leading to a cascade of injury processes and functional deficits, so we examined a number of biomarkers associated with BBB disruption to determine whether VDH deficiency would further compromise the BBB following a stroke. Male Wistar rats were randomly assigned to one of two diet cohorts, VDH-sufficient (VDH^suf) and VDH^def. The VDH^suf group was fed standard rat chow and the VDH^def group got a VDH-null version of the same diet for 8 weeks. Animals from both cohorts were subjected to transient middle cerebral artery occlusion (tMCAO) surgery, killed at 72 h post-stroke, and their brains evaluated for BBB permeability and injury severity using expression of immunoglobulin (IgG), matrix metalloproteinase-9 (MMP-9) activity and alteration of tight junction (TJ) proteins as markers of BBB disruption. We also evaluated modulation of glucose transporter-1 (GLUT1), osteopontin (OPN), β-catenin and vitamin D receptor (VDR) expression in VDH^suf and VDH^def subjects. At the time of MCAO, rats on the VDH^def diet had circulating VDH levels one-fourth that of rats fed control chow. IgG extravasation after MCAO, indicating more severe BBB injury, was significantly higher in the MCAO+VDH^def than the MCAO+VDH^suf rats. Following MCAO, expression of MMP-9, GLUT1, VDR and OPN increased and the TJ proteins occludin and claudin-5 decreased significantly in the VDH^def compared to the VDH^suf group. We also observed significantly lower expression of β-catenin in the MCAO group of both VDH^suf and VDH^def rats. Under these conditions, VDH deficiency itself can compromise the BBB. We think that low serum VDH levels are likely to complicate stroke severity and its chronic consequences.

The role of oligodendrocytes and their progenitors on neural interface technology: A novel perspective on tissue regeneration and repair

Oligodendrocytes and their precursors are critical glial facilitators of neurophysiology, which is responsible for cognition and behavior. Devices that are used to interface with the brain allow for a more in-depth analysis of how neurons and these glia synergistically modulate brain activity. As projected by the BRAIN Initiative, technologies that acquire a high resolution and robust sampling of neural signals can provide a greater insight in both the healthy and diseased brain and support novel discoveries previously unobtainable with the current state of the art. However, a complex series of inflammatory events triggered during device insertion impede the potential applications of implanted biosensors. Characterizing the biological mechanisms responsible for the degradation of intracortical device performance will guide novel biomaterial and tissue regenerative approaches to rehabilitate the brain following injury. Glial subtypes which assist with neuronal survival and exchange of electrical signals, mainly oligodendrocytes, their precursors, and the insulating myelin membranes they produce, are sensitive to inflammation commonly induced from insults to the brain. This review explores essential physiological roles facilitated by oligodendroglia and their precursors and provides insight into their pathology following neurodegenerative injury and disease. From this knowledge, inferences can be made about the impact of device implantation on these supportive glia in order to engineer effective strategies that can attenuate their responses, enhance the efficacy of neural interfacing technology, and provide a greater understanding of the challenges that impede wound healing and tissue regeneration during pathology.

APX3330 Promotes Neurorestorative Effects after Stroke in Type One Diabetic Rats

APX3330 is a selective inhibitor of APE1/Ref-1 redox activity. In this study, we investigate the therapeutic effects and underlying mechanisms of APX3330 treatment in type one diabetes mellitus (T1DM) stroke rats. Adult male Wistar rats were induced with T1DM and subjected to transient middle cerebral artery occlusion (MCAo) and treated with either PBS or APX3330 (10mg/kg, oral gavage) starting at 24h after MCAo, and daily for 14 days. Rats were sacrificed at 14 days after MCAo and, blood brain barrier (BBB) permeability, ischemic lesion volume, immunohistochemistry, cell death assay, Western blot, real time PCR, and angiogenic ELISA array were performed. Compared to PBS treatment, APX3330 treatment of stroke in T1DM rats significantly improves neurological functional outcome, decreases lesion volume, and improves BBB integrity as well as decreases total vessel density and VEGF expression, while significantly increases arterial density in the ischemic border zone (IBZ). APX3330 significantly increases myelin density, oligodendrocyte number, oligodendrocyte progenitor cell number, synaptic protein expression, and induces M2 macrophage polarization in the IBZ of T1DM stroke rats. Compared to PBS treatment, APX3330 treatment significantly decreases plasminogen activator inhibitor type-1 (PAI-1), monocyte chemotactic protein-1 and matrix metalloproteinase 9 (MMP9) and receptor for advanced glycation endproducts expression in the ischemic brain of T1DM stroke rats. APX3330 treatment significantly decreases cell death and MMP9 and PAI-1 gene expression in cultured primary cortical neurons subjected to high glucose and oxygen glucose deprivation, compared to untreated control cells. APX3330 treatment increases M2 macrophage polarization and decreases inflammatory factor expression in the ischemic brain as well as promotes neuroprotective and neurorestorative effects after stroke in T1DM rats.

Cell-Based and Exosome Therapy in Diabetic Stroke

Stroke is a global health concern and it is imperative that therapeutic strategies with wide treatment time frames be developed to improve neurological outcome in patients. Patients with diabetes mellitus who suffer a stroke have worse neurological outcomes and long‐term functional recovery than nondiabetic stroke patients. Diabetes induced vascular damage and enhanced inflammatory milieu likely contributes to worse post stroke outcomes. Diabetic stroke patients have an aggravated pathological cascade, and treatments that benefit nondiabetic stroke patients do not necessarily translate to diabetic stroke patients. Therefore, there is a critical need to develop therapeutics for stroke specifically in the diabetic population. Stem cell based therapy for stroke is an emerging treatment option with wide therapeutic time window. Cell‐based therapies for stroke promote endogenous central nervous system repair and neurorestorative mechanisms such as angiogenesis, neurogenesis, vascular remodeling, white matter remodeling, and also modulate inflammatory and immune responses at the local and systemic level. Emerging evidence suggests that exosomes and their cargo microRNA mediate cell therapy derived neurorestorative effects. Exosomes are small vesicles containing protein and RNA characteristic of its parent cell. Exosomes are transported by biological fluids and facilitate communication between neighboring and remote cells. MicroRNAs, a class of naturally occurring, small noncoding RNA sequences, contained within exosomes can regulate recipient cell's signaling pathways and alter protein expression either acting alone or in concert with other microRNAs. In this perspective article, we summarize current knowledge and highlight the promising future of cell based and exosome therapy for stroke and specifically for diabetic stroke. stemcellstranslationalmedicine2018;7:451–455