Vasogenic edema due to tight junction disruption by matrix metalloproteinases in cerebral ischemia

LncRSPH9-4 Facilitates Meningitic Escherichia coli-Caused Blood-Brain Barrier Disruption via miR-17-5p/MMP3 Axis

Brain microvascular endothelial cells (BMECs) constitute the structural and functional basis for the blood–brain barrier (BBB) and play essential roles in bacterial meningitis. Although the BBB integrity regulation has been under extensive investigation, there is little knowledge regarding the roles of long non-coding RNAs (lncRNAs) in this event. The present study aimed to investigate the roles of one potential lncRNA, lncRSPH9-4, in meningitic E. coli infection of BMECs. LncRSPH9-4 was cytoplasm located and significantly up-regulated in meningitic E. coli-infected hBMECs. Electrical cell-substrate impedance sensing (ECIS) measurement and Western blot assay demonstrated lncRSPH9-4 overexpression in hBMECs mediated the BBB integrity disruption. By RNA-sequencing analysis, 639 mRNAs and 299 miRNAs were significantly differentiated in response to lncRSPH9-4 overexpression. We further found lncRSPH9-4 regulated the permeability in hBMECs by competitively sponging miR-17-5p, thereby increasing MMP3 expression, which targeted the intercellular tight junctions. Here we reported the infection-induced lncRSPH9-4 aggravated disruption of the tight junctions in hBMECs, probably through the miR-17-5p/MMP3 axis. This finding provides new insights into the function of lncRNAs in BBB integrity during meningitic E. coli infection and provides the novel nucleic acid targets for future treatment of bacterial meningitis.

Relationship between chronic hyperglycemia and contrast extravasation in revascularization of symptomatic intracranial atherosclerotic stenosis: A retrospective single-center study

BACKGROUND AND PURPOSE

Contrast extravasation is one of the most common perioperative complications in symptomatic intracranial atherosclerotic stenosis (ICAS) patients after percutaneous transluminal angioplasty and/or stenting (PTAS). This study aimed to investigate the correlations between the relevant serum biochemical indicators of carbohydrate metabolism and the occurrence of contrast extravasation.

METHODS

Patients' demographic characteristics, vascular risk factors and laboratory examination data were collected. Blood routine test, blood biochemical examination and hormone level test within 1 week before surgery were measured in all enrolled subjects. Patients underwent non-contrast CT scans immediately after the endovascular procedure. Follow-up non-contrast CT scans were performed in the next 24 h and repeated as per clinical condition.

RESULTS

104 patients who have undergone effective PTAS were involved in this study. 18 patients have identified as contrast extravasation and there was no obvious abnormality in another 86 cases. There were significant differences in the pre-operative HbA1c, fasting blood sugar and cortisol levels in the subjects regardless of gender between two groups (p < 0.001, p < 0.001 and p = 0.001, respectively). Furthermore, there were statistical differences in E2 and testosterone levels between two groups in both male population (p = 0.035 and p = 0.028, respectively) and female population (p = 0.036 and p = 0.003, respectively). Besides, the AUC value of HbA1c, fasting blood sugar and cortisol levels were all over 0.7 (0.858, 0.780 and 0.752, respectively). The highest AUC value of various combinations was obtained from the combination of HbA1c and cortisol level, which was 0.898.

CONCLUSIONS

Patient with chronic hyperglycemia is closely related to contrast extravasation after PTAS. Specific mechanisms might be explored and regarded as promising candidates to prevent contrast extravasation.

Running Promotes Transformation of Brain Astrocytes Into Neuroprotective Reactive Astrocytes and Synaptic Formation by Targeting Gpc6 Through the STAT3 Pathway

Ischemic stroke is caused by cerebral ischemia upon the blockage of an artery, which results in a high disability rate. Little is known regarding the mechanism of astrocyte function in cerebral ischemia. We aimed to determine the effects of running on the transformation of astrocytes, and subsequent synapse formation. A study of middle cerebral artery occlusion (MCAO) after running in vivo showed that running can promote the transformation of astrocytes toward the neuroprotective phenotype. Our findings of oxygen-glucose deprived astrocytes in vitro after running revealed that these astrocytes transformed into the neuroprotective phenotype, and that the expression of STAT3 and Gpc6 was increased. We confirmed that mechanistically, running can target Gpc6 through the STAT3 pathway and then regulate the number of synapses. We concluded that running promotes synapse proliferation by polarizing astrocytes toward the neuroprotective phenotype and ultimately leads to nerve regeneration.

Adipocyte fatty acid-binding protein exacerbates cerebral ischaemia injury by disrupting the blood-brain barrier

Aims

Adipocyte fatty acid-binding protein (A-FABP) is an adipokine implicating in various metabolic diseases. Elevated circulating levels of A-FABP correlate positively with poor prognosis in ischaemic stroke (IS) patients. No information is available concerning the role of A-FABP in the pathogenesis of IS. Experiments were designed to determine whether or not A-FABP mediates blood–brain barrier (BBB) disruption, and if so, to explore the molecular mechanisms underlying this deleterious effects.

Methods and results

Circulating A-FABP and its cerebral expression were increased in mice after middle cerebral artery occlusion. Genetic deletion and pharmacological inhibition of A-FABP alleviated cerebral ischaemia injury with reduced infarction volume, cerebral oedema, neurological deficits, and neuronal apoptosis; BBB disruption was attenuated and accompanied by reduced degradation of tight junction proteins and induction of matrix metalloproteinases-9 (MMP-9). In patients with acute IS, elevated circulating A-FABP levels positively correlated with those of MMP-9 and cerebral infarct volume. Mechanistically, ischaemia-induced elevation of A-FABP selectively in peripheral blood monocyte-derived macrophages and cerebral resident microglia promoted MMP-9 transactivation by potentiating JNK/c-Jun signalling, enhancing degradation of tight junction proteins and BBB leakage. The detrimental effects of A-FABP were prevented by pharmacological inhibition of MMP-9.

Conclusion

A-FABP is a key mediator of cerebral ischaemia injury promoting MMP-9-mediated BBB disruption. Inhibition of A-FABP is a potential strategy to improve IS outcome.

Noscapine alleviates cerebral damage in ischemia-reperfusion injury in rats

With high unmet medical needs, stroke remains an intensely focused research area. Although noscapine is a neuroprotective agent, its mechanism of action in ischemic-reperfusion (I-R) injury is yet to be ascertained. We investigated the effect of noscapine on the molecular mechanisms of cell damage using yeast, and its neuroprotection on cerebral I-R injury in rats. Yeast, both wild-type and Δtrx2 strains, was evaluated for cell growth and viability, and oxidative stress to assess the noscapine effect at 8, 10, 12, and 20 μg/ml concentrations. The neuroprotective activity of noscapine (5 and 10 mg/kg; po for 8 days) was investigated in rats using middle cerebral artery occlusion-induced I-R injury. Infarct volume, neurological deficit, oxidative stress, myeloperoxidase activity, and histological alterations were determined in I-R rats. In vitro yeast assays exhibited significant antioxidant activity and enhanced cell tolerance against oxidative stress after noscapine treatment. Similarly, noscapine pretreatment significantly reduced infarct volume and edema in the brain. The neurological deficit was decreased and oxidative stress biomarkers, superoxide dismutase activity and glutathione levels, were significantly increased while lipid peroxidation showed significant decrease in comparison to vehicle-treated I-R rats. Myeloperoxidase activity, an indicator of inflammation, was also reduced significantly in treated rats; histological changes were attenuated with noscapine. The study demonstrates the protective effect of noscapine in yeast and I-R rats by improving cell viability and attenuating neuronal damage, respectively. This protective activity of noscapine could be attributed to potent free radical scavenging and inhibition of inflammation in cerebral ischemia-reperfusion injury.

Circulating tight-junction proteins are potential biomarkers for blood-brain barrier function in a model of neonatal hypoxic/ischemic brain injury

Background

Neonatal encephalopathy often leads to lifelong disabilities with limited treatments currently available. The brain vasculature is an important factor in many neonatal neurological disorders but there is a lack of diagnostic tools to evaluate the brain vascular dysfunction of neonates in the clinical setting. Measurement of blood–brain barrier tight-junction (TJ) proteins have shown promise as biomarkers for brain injury in the adult. Here we tested the biomarker potential of tight-junctions in the context of neonatal brain injury.

Methods

The levels of TJ-proteins (occluding, claudin-5, and zonula occludens protein 1) in both blood plasma and cerebrospinal fluid (CSF) as well as blood–brain barrier function via ¹⁴C-sucrose (342 Da) and Evans blue extravasation were measured in a hypoxia/ischemia brain-injury model in neonatal rats.

Results

Time-dependent changes of occludin and claudin-5 levels could be measured in blood and CSF after hypoxia/ischemia with males generally having higher levels than females. The levels of claudin-5 in CSF correlated with the severity of the brain injury at 24 h post- hypoxia/ischemia. Simultaneously, we detected early increase in blood–brain barrier-permeability at 6 and 24 h after hypoxia/ischemia.

Conclusions

Levels of circulating claudin-5 and occludin are increased after hypoxic/ischemic brain injuries and blood–brain barrier-impairment and have promise as early biomarkers for cerebral vascular dysfunction and as a tool for risk assessment of neonatal brain injuries.

Identifying Biomarkers Associated with Venous Infarction in Acute/Subacute Cerebral Venous Thrombosis

Among cerebral venous thrombosis (CVT) patients, those with venous infarction have more severe clinical presentations and worse outcomes. Identifying biomarkers associated with venous infarction in CVT may help understand the pathogenesis and provide potentially useful therapeutic markers. Fifty-two CVT patients were prospectively recruited and divided into three groups: acute/subacute CVT with venous infarction (ASVI, n=30), without venous infarction (ASOVI, n=13), and chronic CVT (n=9). Blood brain barrier (BBB) permeability-related proteins, including claudin-5, occludin, matrix metalloproteinase-9, glial fibrillary acidic protein, and S100B, and inflammation-related factor high-sensitivity C-reactive protein (hs-CRP), were tested in serum and/or cerebrospinal fluid upon admission. We compared these biomarkers between the three groups and investigated their associations with venous infarction and clinical symptom severity in acute/subacute CVT patients on admission using the NIH Stroke Scale (NIHSS). Serum hs-CRP was significantly higher in acute/subacute CVT patients than chronic CVT patients. For acute/subacute CVT patients, levels were significantly higher in the ASVI group than the ASOVI group for serum claudin-5 (medians 2.80 vs. 2.50 mg/I, respectively, P = 0.039) and hs-CRP (medians 17.25 vs. 2.27 mg/l, respectively, P = 0.003). Both these biomarkers, analyzed as categorical or continuous variables, were also significantly associated with venous infarction in acute/subacute CVT patients after logistic regression analysis. Additionally, hs-CRP was positively correlated with the NIHSS (r = 0.710, P < 0.001) on admission in acute/subacute CVT patients. In CVT patients, venous infarction was associated with BBB disruption and potentially inflammation. Hs-CRP might serve as a biomarker reflecting the clinical severity of CVT in the acute/subacute stages.

How matrix metalloproteinase (MMP)-9 (rs3918242) polymorphism affects MMP-9 serum concentration and associates with autism spectrum disorders: A case-control study in Iranian population

The aim of this project was to evaluate the relationship of matrix metalloproteinase-9 (MMP-9) genetic variation and its serum concentration with autism spectrum disorder (ASD). One hundred ASD and 120 controls were enrolled in this study. Genomic DNA was extracted from blood and MMP-9 polymorphism was determined by polymerase chain reaction restriction fragment length polymorphism and serum levels were measured by enzyme-linked immunosorbent assay. The frequencies of CC, CT, and TT genotypes were 72%, 26%, and 2% in controls and 31%, 57%, and 12% in ASD, respectively. The frequencies of C and T alleles in ASD were 59.5% and 40.5%, and controls were 86% and 14%, respectively. There is a significant increase in serum MMP-9 levels in ASD as compared to controls. We have also shown that TT genotype is significantly associated with increase serum MMP-9 levels in patients (TT, CT, and CC serum levels were 91.77 ± 10.53, 70.66 ± 7.21, and 38.66 ± 5.52 and in controls were 55.55 ± 11.39, 42.66 ± 7.85, and 30.55 ± 6.34 ng/ml, respectively). It is concluded that there is a significant association between rs3918242 MMP-9 polymorphism and its serum concentration with autism. We also suggest that TT genotype is associated with increased MMP9 expression and may be a risk factor for ASD.

Exposure to traffic-generated air pollution promotes alterations in the integrity of the brain microvasculature and inflammation in female ApoE-/- mice

Traffic-generated air pollutants have been correlated with alterations in blood-brain barrier (BBB) integrity, which is associated with pathologies in the central nervous system (CNS). Much of the existing literature investigating the effects of air pollution in the CNS has predominately been reported in males, with little known regarding the effects in females. As such, this study characterized the effects of inhalation exposure to mixed vehicle emissions (MVE), as well as the presence of female sex hormones, in the CNS of female ApoE^-/- mice, which included cohorts of both ovariectomized (ov-) and ovary-intact (ov+) mice. Ov + and ov- were placed on a high-fat diet and randomly grouped to be exposed to either filtered-air (FA) or MVE (200 PM/m³: 50 μg PM/m³ gasoline engine + 150 μg PM/m³ from diesel engine emissions) for 6 h/d, 7d/wk, for 30d. MVE-exposure resulted in altered cerebral microvascular integrity and permeability, as determined by the decreased immunofluorescent expression of tight junction (TJ) proteins, occludin, and claudin-5, and increased IgG extravasation into the cerebral parenchyma, compared to FA controls, regardless of ovary status. Associated with the altered cerebral microvascular integrity, we also observed an increase in matrix metalloproteinases (MMPs) -2/9 activity in the MVE ov+, MVE ov-, and FA ov- groups, compared to FA ov+. There was also elevated expression of intracellular adhesion molecule (ICAM)-1, inflammatory interleukins (IL-1, IL-1β), and tumor necrosis factor (TNF-α) mRNA in the cerebrum of MVE ov + and MVE ov- animals. IκB kinase (IKK) subunits IKKα and IKKβ mRNA expressions were upregulated in the cerebrum of MVE ov- and FA ov- mice. Our findings indicate that MVE exposure mediates altered integrity of the cerebral microvasculature correlated with increased MMP-2/9 activity and inflammatory signaling, regardless of female hormones present.

Association of Matrix Metalloproteinase 9 and Cellular Fibronectin and Outcome in Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

Introduction: The role of matrix metalloproteinase 9 (MMP-9) and cellular fibronectin (c-Fn) in acute ischemic stroke is controversial. We systematically reviewed the literature to investigate the association of circulating MMP-9 and c-Fn levels and MMP-9 rs3918242 polymorphism with the risk of three outcome measures after stroke.

Methods: We searched English and Chinese databases to identify eligible studies. Outcomes included severe brain edema, hemorrhagic transformation, and poor outcome (modified Rankin scale score ≥3). We estimated standardized mean differences (SMDs) and pooled odds ratios (ORs) with 95% confidence intervals (CIs).

Results: Totally, 28 studies involving 7,239 patients were included in the analysis of circulating MMP-9 and c-Fn levels. Meta-analysis indicated higher levels of MMP-9 in patients with severe brain edema (SMD, 0.76; 95% CI, 0.18–1.35; four studies, 419 patients) and hemorrhagic transformation (SMD, 1.00; 95% CI, 0.41–1.59; 11 studies, 1,709 patients) but not poor outcome (SMD, 0.30; 95% CI, −0.12 to 0.72; four studies, 759 patients). Circulating c-Fn levels were also significantly higher in patients with severe brain edema (SMD, 1.55; 95% CI, 1.18–1.93; four studies, 419 patients), hemorrhagic transformation (SMD, 1.75; 95% CI, 0.72–2.78; four studies, 458 patients), and poor outcome (SMD, 0.46; 95% CI, 0.16–0.76; two studies, 210 patients). Meta-analysis of three studies indicated that the MMP-9 rs3918242 polymorphism may be associated with hemorrhagic transformation susceptibility under the dominant model (TT + CT vs. CC: OR, 0.621; 95% CI, 0.424–0.908; P = 0.014). No studies reported the association between MMP-9 rs3918242 polymorphism and brain edema or functional outcome after acute stroke.

Conclusion: Our meta-analysis showed that higher MMP-9 levels were seen in stroke patients with severe brain edema and hemorrhagic transformation but not poor outcome. Circulating c-Fn levels appear to be associated with all three outcomes including severe brain edema, hemorrhagic transformation, and poor functional outcome. The C-to-T transition at the MMP-9 rs3918242 gene appears to reduce the risk of hemorrhagic transformation.

Molecular Biology of Atherosclerotic Ischemic Strokes

Among the causes of global death and disability, ischemic stroke (also known as cerebral ischemia) plays a pivotal role, by determining the highest number of worldwide mortality, behind cardiomyopathies, affecting 30 million people. The etiopathogenetic burden of a cerebrovascular accident could be brain ischemia (~80%) or intracranial hemorrhage (~20%). The most common site when ischemia occurs is the one is perfused by middle cerebral arteries. Worse prognosis and disablement consequent to brain damage occur in elderly patients or affected by neurological impairment, hypertension, dyslipidemia, and diabetes. Since, in the coming years, estimates predict an exponential increase of people who have diabetes, the disease mentioned above constitutes together with stroke a severe social and economic burden. In diabetic patients after an ischemic stroke, an exorbitant activation of inflammatory molecular pathways and ongoing inflammation is responsible for more severe brain injury and impairment, promoting the advancement of ischemic stroke and diabetes. Considering that the ominous prognosis of ischemic brain damage could by partially clarified by way of already known risk factors the auspice would be modifying poor outcome in the post-stroke phase detecting novel biomolecules associated with poor prognosis and targeting them for revolutionary therapeutic strategies.

Angiogenesis and Blood-Brain Barrier Permeability in Vascular Remodeling after Stroke

Angiogenesis, the growth of new blood vessels, is a natural defense mechanism helping to restore oxygen and nutrient supply to the affected brain tissue following an ischemic stroke. By stimulating vessel growth, angiogenesis may stabilize brain perfusion, thereby promoting neuronal survival, brain plasticity, and neurologic recovery. However, therapeutic angiogenesis after stroke faces challenges: new angiogenesis-induced vessels have a higher than normal permeability, and treatment to promote angiogenesis may exacerbate outcomes in stroke patients. The development of therapies requires elucidation of the precise cellular and molecular basis of the disease. Microenvironment homeostasis of the central nervous system is essential for its normal function and is maintained by the blood-brain barrier (BBB). Tight junction proteins (TJP) form the tight junction (TJ) between vascular endothelial cells (ECs) and play a key role in regulating the BBB permeability. We demonstrated that after stroke, new angiogenesis-induced vessels in peri-infarct areas have abnormally high BBB permeability due to a lack of major TJPs in ECs. Therefore, promoting TJ formation and BBB integrity in the new vessels coupled with speedy angiogenesis will provide a promising and safer treatment strategy for improving recovery from stroke. Pericyte is a central neurovascular unite component in vascular barriergenesis and are vital to BBB integrity. We found that pericytes also play a key role in stroke-induced angiogenesis and TJ formation in the newly formed vessels. Based on these findings, in this article, we focus on regulation aspects of the BBB functions and describe cellular and molecular special features of TJ formation with an emphasis on role of pericytes in BBB integrity during angiogenesis after stroke.

Dysregulation of the MMP/TIMP Proteolytic System in Subependymal Giant Cell Astrocytomas in Patients With Tuberous Sclerosis Complex: Modulation of MMP by MicroRNA-320d In Vitro

Tuberous sclerosis complex (TSC), a rare genetic disorder caused by a mutation in the TSC1 or TSC2 gene, is characterized by the growth of hamartomas in several organs. This includes the growth of low-grade brain tumors, known as subependymal giant cell astrocytomas (SEGA). Previous studies have shown differential expression of genes related to the extracellular matrix in SEGA. Matrix metalloproteinases (MMPs), and their tissue inhibitors (TIMPs) are responsible for remodeling the extracellular matrix and are associated with tumorigenesis. This study aimed to investigate the MMP/TIMP proteolytic system in SEGA and the regulation of MMPs by microRNAs, which are important post-transcriptional regulators of gene expression. We investigated the expression of MMPs and TIMPs using previously produced RNA-Sequencing data, real-time quantitative PCR and immunohistochemistry in TSC-SEGA samples and controls. We found altered expression of several MMPs and TIMPs in SEGA compared to controls. We identified the lowly expressed miR-320d in SEGA as a potential regulator of MMPs, which can decrease MMP2 expression in human fetal astrocyte cultures. This study provides evidence of a dysregulated MMP/TIMP proteolytic system in SEGA of which MMP2 could be rescued by microRNA-320d. Therefore, further elucidating microRNA-mediated MMP regulation may provide insights into SEGA pathogenesis and identify novel therapeutic targets.

Therapeutic treatment with vitamin C reduces focal cerebral ischemia-induced brain infarction in rats by attenuating disruptions of blood brain barrier and cerebral neuronal apoptosis

Stroke is a major public health problem and ranks third most common cause of death in adults worldwide. Thrombolysis with recombinant tissue plasminogen activator and endovascular thrombectomy are the main revascularization therapies for acute ischemic stroke. However, ischemia-reperfusion injury, mainly caused by oxidative/nitrosative stress injury, after revascularization therapy can result in worsening outcomes. For better clinical prognosis, more and more studies have focused on the pharmaceutical neuroprotective therapies against free radical damage. The impact of vitamin C (ascorbic acid) on oxidative stress-related diseases is moderate because of its limited oral bioavailability and rapid clearance. However, recent evidence of the clinical benefit of parenteral vitamin C administration has emerged, especially in critical care. In this study we demonstrated that parenteral administration of vitamin C significantly improved neurological deficits and reduced brain infarction and brain edema by attenuating the transient middle cerebral artery occlusion (tMCAO)-induced nitrosative stress, inflammatory responses, and the resultant disruptions of blood brain barrier and cerebral neuronal apoptosis. These results suggest that parenteral administration of vitamin C has potential as an adjuvant agent with intravenous thrombolysis or endovascular thrombectomy in acute treatment of ischemic stroke.

Methylene blue post-treatment improves hypoxia-ischemic recovery in a neonatal rat model

Recent work suggested that methylene blue (MB) has beneficial effects in a variety of neurological disorders, while its role in neonatal hypoxic-ischemic (HI) encephalopathy is still unclear. The current study was designed to investigate the effects of MB on HI-induced brain damage and its underlying mechanisms. The results showed that MB treatment can strongly attenuate HI-induced brain loss and neuronal damage in the cortex and hippocampus of neonatal rats. Further mechanistic analysis suggested that MB treatment was able to significantly reduce blood-brain barrier disruption after HI insult. In addition, MB profoundly inhibited microglia and astrocyte activation and the pro-inflammatory cytokines production in neonatal cortex and hippocampus after HI. Further, MB treatment resulted in dramatic suppression of oxidative damage, as evidenced by robustly decreased DHE and protein carbonyls levels in HI brain. Moreover, MB strongly preserved mitochondrial function by repressing HI-induced mitochondrial fragmentation, and the following neuronal death in cortex and hippocampus. Finally, behavioral tests revealed that MB significantly improved the spatial reference memory and motor coordination of neonatal HI rats. Taken together, these findings demonstrate that the mechanisms behind neuroprotective actions of methylene blue are multifactorial, including suppression of oxidative stress and neuroinflammation, restoration of mitochondrial function, as well as attenuation of blood-brain barrier disruption. Our study might provide further directions for MB as a promising option in neonatal HI encephalopathy therapy.

Matrix Metalloproteinase-9 and Monocyte Chemoattractant Protein-1 Are Associated With Collateral Status in Acute Ischemic Stroke With Large Vessel Occlusion

BACKGROUND AND PURPOSE

In ischemic stroke, inflammatory status may condition the development of collateral circulation. Here we assessed the relationship between systemic inflammatory biomarkers and collateral status in large vessel occlusion before mechanical thrombectomy.

METHODS

HIBISCUS-STROKE is a cohort study including acute ischemic stroke patients with large vessel occlusion treated with mechanical thrombectomy following admission magnetic resonance imaging. MMP-9 (matrix metalloproteinase-9) and MCP-1 (monocyte chemoattractant protein-1) were measured on blood sampling collected at admission. Collateral status was assessed on pretreatment Digital subtraction angiography and categorized into poor (Higashida score, 0-2) and good (Higashida score, 3-4). A multiple logistic regression model was performed to detect independent markers of good collateral status.

RESULTS

One hundred and twenty-two patients were included, of them 71 patients (58.2%) had a good collateral status. In univariate analysis, low MMP-9 levels (P=0.01), high MCP-1 levels (P<0.01), a low National Institute of Health Stroke Score (P=0.046), a high diastolic blood pressure (P=0.049), the absence of tandem occlusion (P=0.046), a high Alberta Stroke Program Early CT Score (P<0.01) and a low volume on the diffusion-weighted imaging (P<0.01) were associated with good collateral status. Following multivariate analysis, low MMP-9 levels (P=0.02) and high MCP-1 levels (P<0.01) remained associated with good collateral status.

CONCLUSIONS

Low MMP-9 and high MCP-1 levels were associated with good pretreatment collateral status in patients with acute ischemic stroke with large vessel occlusion. These results might suggest a relationship between collateral status and inflammation.

Combined Treatment With 2-(2-Benzofu-Ranyl)-2-Imidazoline and Recombinant Tissue Plasminogen Activator Protects Blood-Brain Barrier Integrity in a Rat Model of Embolic Middle Cerebral Artery Occlusion

Recombinant tissue plasminogen activator (rt-PA) is used to treat acute ischemic stroke but is only effective if administered within 4.5 h after stroke onset. Delayed rt-PA treatment causes blood-brain barrier (BBB) disruption and hemorrhagic transformation. The compound 2-(-2-benzofuranyl)-2-imidazoline (2-BFI), a newly discovered antagonist of high-affinity postsynaptic N-methyl-D-aspartate (NMDA) receptors, has been shown to have neuroprotective effects in ischemia. Here, we investigated whether combining 2-BFI and rt-PA can ameliorate BBB disruption and prolong the therapeutic window in a rat model of embolic middle cerebral artery occlusion (eMCAO). Ischemia was induced in male Sprague Dawley rats by eMCAO, after which they were treated with 2-BFI (3 mg/kg) at 0.5 h in combination with rt-PA (10 mg/kg) at 6 or 8 h. Control rats were treated with saline or 2-BFI or rt-PA. Combined therapy with 2-BFI and rt-PA (6 h) reduced the infarct volume, denatured cell index, BBB permeability, and brain edema. This was associated with increased expression of aquaporin 4 (AQP4) and tight junction proteins (occludin and ZO-1) and downregulation of intercellular adhesion molecule 1 (ICAM-1) and matrix metalloproteinases 2 and 9 (MMP2 and MMP9). We conclude that 2-BFI protects the BBB from damage caused by delayed rt-PA treatment in ischemia. 2-BFI may therefore extend the therapeutic window up to 6 h after stroke onset in rats and may be a promising therapeutic strategy for humans. However, mechanisms to explain the effects oberved in the present study are not yet elucidated.

Matrix Metalloproteinase-9 Relationship With Infarct Growth and Hemorrhagic Transformation in the Era of Thrombectomy

Objective: To assess the relationship between matrix metalloproteinase 9 (MMP-9), a proteolytic enzyme involved in the breakdown of the blood-brain barrier, and infarct growth and hemorrhagic transformation in acute ischemic stroke (AIS) with large vessel occlusion (LVO) in the era of mechanical thrombectomy (MT) using the kinetics of MMP-9 and sequential magnetic resonance imaging (MRI).

Methods: HIBISCUS-STROKE is a cohort study including AIS patients with LVO treated with MT following admission MRI. Patients underwent sequential assessment of MMP-9, follow-up CT at day 1, and MRI at day 6. The CT scan at day 1 classified any hemorrhagic transformation according to the European Co-operative Acute Stroke Study-II (ECASS II) classification. Infarct growth was defined as the difference between final Fluid-Attenuated Inversion Recovery volume and baseline diffusion-weighted imaging volume. Conditional logistic regression analyses were adjusted for main confounding variables including reperfusion status.

Results: One hundred and forty-eight patients represent the study population. A high MMP-9 level at 6 h from admission (H6) (p = 0.02), a high glucose level (p = 0.01), a high temperature (p = 0.04), and lack of reperfusion (p = 0.02) were associated with infarct growth. A high MMP-9 level at H6 (p = 0.03), a high glucose level (p = 0.03) and a long delay from symptom onset to groin puncture (p = 0.01) were associated with hemorrhagic transformation.

Conclusions: In this MT cohort study, MMP-9 level at H6 predicts infarct growth and hemorrhagic transformation.

Inhibition of the NLRP3 inflammasome reduces brain edema and regulates the distribution of aquaporin-4 after cerebral ischaemia-reperfusion

AIMS

Brain edema is a common threat to life in ischaemic brain injury. The NLRP3 inflammasome promotes the inflammatory injury after ischaemic stroke. Previous studies have shown that aquaporin-4 (AQP4) modulates brain water transport and endothelin-1 (ET-1) induces cerebral edema. However, the contribution of the NLRP3 inflammasome to regulation of brain edema and blood-brain barrier (BBB) disruption in cerebral ischaemia-reperfusion is elusive. The aim of this study is to investigate the effect of inhibition of the NLRP3 inflammasome by MCC950 on regulation of cerebral edema, BBB disruption and the expression of AQP4 and ET-1 in cerebral ischaemia-reperfusion.

MAIN METHODS

The male C57BL/6 mice were used to establish the experimental transient middle cerebral artery occlusion (tMCAO) model. The mice were intraperitoneally injected with MCC950. Changes in NLRP3, IL-1β, IL-18, the pyroptosis protein gasdermin D (GSDMD), brain water content, AQP4 and ET-1 in brain tissue were detected.

KEY FINDINGS

MCC950 inhibited NLRP3 and GSDMD after tMCAO. MCC950 improved cerebral edema and alleviated the damage of BBB after tMCAO. The levels of AQP4 and ET-1 were decreased by MCC950. In addition, MCC950 regulated the distribution of AQP4 after tMCAO in mice.

SIGNIFICANCE

The NLRP3 inflammasome facilitated brain edema and BBB disruption after cerebral ischaemia-reperfusion in mice, and NLRP3 inflammasome inhibition with MCC950 regulated the expression and distribution of AQP4 in the infarct area. Hence, the NLRP3 inflammasome is considered to be an important target for the treatment of brain edema in cerebral ischaemia-reperfusion, and MCC950 has potential value for ischaemic stroke treatment.

Shengui Sansheng Pulvis maintains blood-brain barrier integrity by vasoactive intestinal peptide after ischemic stroke

Background Shengui Sansheng Pulvis (SSP) has about 300 years history used for stroke treatment, and evidences suggest it has beneficial effects on neuro-angiogenesis and cerebral energy metabolic amelioration post-stroke. However, its protective action and mechanisms on blood-brain barrier (BBB) is still unknown. Purpose Based on multiple neuroprotective properties of vasoactive intestinal peptide (VIP) in neurological disorders, we investigate if SSP maintaining BBB integrity is associated with VIP pathway in rat permanent middle cerebral artery occlusion (MCAo) model. Methods Three doses of SSP extraction were administered orally. Evaluations of motor and balance abilities and detection of brain edema were performed, and BBB permeability were assessed by Evans blue (EB) staining. Primary brain microvascular endothelial cells (BMECs) were subjected to oxygen-glucose deprivation, and incubated with high dose SSP drug-containing serum and VIP-antagonist respectively. Transendothelial electrical resistance (TEER) assay and Tetramethylrhodamine isothiocyanate (TRITC)-dextran (4.4 kDa) and fluorescein isothiocyanate (FITC)-dextran (70 kDa) were used to evaluate the features of paracellular junction. Western blot detected the expressions of Claudin-5, ZO-1, Occludin and VE-cadherin, matrix metalloproteinase (MMP) 2/9 and VIP receptors 1/2, and immunofluorescence staining tested VIP and Claudin-5 expressions. Results Our results show that SSP significantly reduces EB infiltration in dose-dependent manner in vivo and attenuates TRITC- dextran and FITC-dextran diffusion in vitro, and strengthens endothelial junctional complexes as represented by decreasing Claudin-5, ZO-1, Occludin and VE-cadherin degradations and MMP 2/9 expression, as well as promoting TEER in BMECs after ischemia. Moreover, it suggests that SSP notably enhances VIP and its receptors 1/2 expressions. VIP-antagonist exacerbates paracellular barrier of BMECs, while the result is reversed after incubation with high dose SSP drug-containing serum. Additionally, SSP also improve brain edema and motor and balance abilities after ischemic stroke. Conclusions we firstly demonstrate that the ameliorated efficacy of SSP on BBB permeability is related to the enhancements of VIP and its receptors, suggesting SSP might be an effective therapeutic agent on maintaining BBB integrity post-stroke.

Increased matrix metalloproteinases expression in tuberous sclerosis complex: modulation by microRNA 146a and 147b in vitro

AIM

Matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors (TIMPs) control proteolysis within the extracellular matrix (ECM) of the brain. Dysfunction of this enzymatic system due to brain inflammation can disrupt the blood-brain barrier (BBB) and has been implicated in the pathogenesis of epilepsy. However, this has not been extensively studied in the epileptogenic human brain.

METHODS

We investigated the expression and cellular localization of major MMPs (MMP2, MMP3, MMP9 and MMP14) and TIMPs (TIMP1, TIMP2, TIMP3 and TIMP4) using quantitative real-time polymerase chain reaction (RT-PCR) and immunohistochemistry in resected epileptogenic brain tissue from patients with tuberous sclerosis complex (TSC), a severe neurodevelopmental disorder characterized by intractable epilepsy and prominent neuroinflammation. Furthermore, we determined whether anti-inflammatory microRNAs, miR146a and miR147b, which can regulate gene expression at the transcriptional level, could attenuate dysregulated MMP and TIMP expression in TSC tuber-derived astroglial cultures.

RESULTS

We demonstrated higher mRNA and protein expression of MMPs and TIMPs in TSC tubers compared to control and perituberal brain tissue, particularly in dysmorphic neurons and giant cells, as well as in reactive astrocytes, which was associated with BBB dysfunction. More importantly, IL-1β-induced dysregulation of MMP3, TIMP2, TIMP3 and TIMP4 could be rescued by miR146a and miR147b in tuber-derived TSC cultures.

CONCLUSIONS

This study provides evidence of dysregulation of the MMP/TIMP proteolytic system in TSC, which is associated with BBB dysfunction. As dysregulated MMP and TIMP expression can be ameliorated in vitro by miR146a and miR147b, these miRNAs deserve further investigation as a novel therapeutic approach.

Fisetin Prolongs Therapy Window of Brain Ischemic Stroke Using Tissue Plasminogen Activator: A Double-Blind Randomized Placebo-Controlled Clinical Trial

Recombinant tissue plasminogen activator (rt-PA) can be utilized to treat ischemic stroke with safety and effectiveness but limited by a narrow therapeutic window. In the present clinical trial among patients with stroke, we sought to evaluate the potential of fisetin to extend the therapeutic window of rt-PA treatment. Patients with stroke were divided based on their onset-to-treatment time (OTT) and then randomly assigned to receive the rt-PA treatment combined with fisetin or placebo. Primary outcome was evaluated using the National Institutes of Health Stroke scale (NIHSS), and secondary outcome was assessed by serum levels of matrix metalloproteinase (MMP) 2, MMP 9, and C-reactive protein (CRP). Fisetin dramatically improved the treatment outcomes of the patients with stroke in the delayed OTT strata, as revealed by lower NIHSS scores. The beneficial effect of fisetin was likely attributable to reduced levels of MMP-2, MMP-9, and CRP in the serum, as evidenced by strong linear correlations between serum levels of such markers with the NIHSS scores in all enrolled patients. Fisetin may possess the potential to supplement traditional rt-PA treatments among patients with stroke, particularly for those with delayed OTT, and thereby extend the otherwise narrow therapeutic window and improve the treatment outcomes.

Surgically-induced brain injury: where are we now?

Neurosurgical procedures cause inevitable brain damage from the multitude of surgical manipulations utilized. Incisions, retraction, thermal damage from electrocautery, and intraoperative hemorrhage cause immediate and long-term brain injuries that are directly linked to neurosurgical operations, and these types of injuries, collectively, have been termed surgical brain injury (SBI). For the past decade, a model developed to study the underlying brain pathologies resulting from SBI has provided insight on cellular mechanisms and potential therapeutic targets. This model, as seen in a rat, mouse, and rabbit, mimics a neurosurgical operation and causes commonly encountered post-operative complications such as brain edema, neuroinflammation, and hemorrhage. In this review, we elaborate on SBI and its clinical impact, the SBI animal models and their clinical relevance, the importance of applying therapeutics before neurosurgical procedures (i.e., preconditioning), and the new direction of applying venom-derived proteins to attenuate SBI.

Selective Liposomal Transport through Blood Brain Barrier Disruption in Ischemic Stroke Reveals Two Distinct Therapeutic Opportunities

The development of effective therapies for stroke continues to face repeated translational failures. Brain endothelial cells form paracellular and transcellular barriers to many blood-borne therapies, and the development of efficient delivery strategies is highly warranted. Here, in a mouse model of stroke, we show selective recruitment of clinically used liposomes into the ischemic brain that correlates with biphasic blood brain barrier (BBB) breakdown. Intravenous administration of liposomes into mice exposed to transient middle cerebral artery occlusion took place at early (0.5 and 4 h) and delayed (24 and 48 h) time points, covering different phases of BBB disruption after stroke. Using a combination of in vivo real-time imaging and histological analysis we show that selective liposomal brain accumulation coincides with biphasic enhancement in transcellular transport followed by a delayed impairment to the paracellular barrier. This process precedes neurological damage in the acute phase and maintains long-term liposomal colocalization within the neurovascular unit, which could have great potential for neuroprotection. Levels of liposomal uptake by glial cells are similarly selectively enhanced in the ischemic region late after experimental stroke (2-3 days), highlighting their potential for blocking delayed inflammatory responses or shifting the polarization of microglia/macrophages toward brain repair. These findings demonstrate the capability of liposomes to maximize selective translocation into the brain after stroke and identify two windows for therapeutic manipulation. This emphasizes the benefits of selective drug delivery for efficient tailoring of stroke treatments.

Suppression of Cerebral Ischemia/Reperfusion Injury by Efficient Release of Encapsulated Ifenprodil From Liposomes Under Weakly Acidic pH Conditions

Although N-methyl-d-aspartate receptor antagonists are hopeful therapeutic agents against cerebral ischemia/reperfusion (I/R) injury, effective approaches are needed to allow such agents to pass through the blood-brain barrier, thus increasing bioavailability of the antagonists to realize secure treatment. We previously demonstrated the usefulness of liposomal delivery of neuroprotectants via spaces between the disrupted blood-brain barrier induced after cerebral I/R. In the present study, a liposomal formulation of an N-methyl-d-aspartate receptor antagonist, ifenprodil, was newly designed; and the potential of liposomal ifenprodil was evaluated in transient middle cerebral artery occlusion rats. Ifenprodil was encapsulated into liposomes by a remote loading method using pH gradient between internal and external water phases of liposomes, focusing on differences of its solubility in water depending on pH. The encapsulated ifenprodil could be quickly released from the liposomes in vitro under a weakly acidic pH condition, which is a distinctive condition after cerebral I/R. Liposomal ifenprodil treatment significantly alleviated I/R-induced increase in permeability of the BBB by inhibiting superoxide anion production, resulting in ameliorating ischemic brain damage. Taken together, these results suggest that Ifen-Lip could become a hopeful neuroprotectant for cerebral I/R injury via efficient release of the encapsulated ifenprodil under weakly acidic pH conditions.

Hesperidin reduces adverse symptomatic intracerebral hemorrhage by promoting TGF-β1 for treating ischemic stroke using tissue plasminogen activator

Treatment with recombinant tissue plasminogen activator (rt-PA) is the most effective therapeutic option against brain ischemic stroke at the present time. However, elevated incidence of symptomatic intracerebral hemorrhage (SIH) greatly hinders ideal treatment outcome of rt-PA. We sought to assess the impacts of hesperidin on SIH following rt-PA therapies. Patients with ischemic stroke were assigned into two groups in a random fashion, to receive either rt-PA + placebo (Pc) or rt-PA + hesperidin. Treatment outcome was evaluated 24 h after the initial reperfusion using the transcranial Doppler ultrasonography (TCD) and the NIH Stroke Scale (NIHSS). Further, serum concentrations of transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-2, and MMP-9 were examined. Following the initial administration, stroke patients continued to receive either daily Pc or daily hesperidin, and the treatment outcome after 7 days was examined using the TCD, NIHSS, Glasgow Outcome Scale (GOS), and the Modified Rankin Scale (MRS). Combined treatment of rt-PA with hesperidin yielded significant improvement of outcomes, as revealed by better TCD and NIHSS scores as well as decreased SIH incidences, which could be attributable to elevation of TGF-β1 and reduction in serum levels of both MMP-2 and MMP-9 caused by hesperidin. Follow-up hesperidin treatment for 7 consecutive days also markedly enhanced the recovery of stroke patients, as indicated by TCD, MRS, GOS, and NIHSS. Findings of the present study strongly suggested potential clinical application of hesperidin supplement in rt-PA therapies to reduce SIH and thereby improve the treatment outcomes of rt-PA in patients with ischemic stroke.

Dietary Anthocyanins and Stroke: A Review of Pharmacokinetic and Pharmacodynamic Studies

Cerebrovascular accidents are currently the second major cause of death and the third leading cause of disability in the world, according to the World Health Organization (WHO), which has provided protocols for stroke prevention. Although there is a multitude of studies on the health benefits associated with anthocyanin (ACN) consumption, there is no a rigorous systematization of the data linking dietary ACN with stroke prevention. This review is intended to present data from epidemiological, in vitro, in vivo, and clinical studies dealing with the stroke related to ACN-rich diets or ACN supplements, along with possible mechanisms of action revealed by pharmacokinetic studies, including ACN passage through the blood-brain barrier (BBB).

Cerebral Expression of Glial Fibrillary Acidic Protein, Ubiquitin Carboxy-Terminal Hydrolase-L1, and Matrix Metalloproteinase 9 After Traumatic Brain Injury and Secondary Brain Insults in Rats

Glial fibrillary acidic protein (GFAP), ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1), and matrix metalloproteinase 9 (MMP-9) are potential biomarkers of traumatic brain injury (TBI) but also of secondary insults to the brain. The aim of this study was to describe the cerebral distribution of GFAP, UCH-L1, and MMP-9 in a rat model of diffuse TBI associated with standardized hypoxia-hypotension (HH). Adult male Sprague-Dawley rats were allocated to Sham (n = 10), TBI (n = 10), HH (n = 10), and TBI+HH (n = 10) groups. After 4 hours, brains were rapidly removed and immunostaining of GFAP, UCH-L1, and MMP-9 was performed. Areas of interest that have been described as particularly sensitive to hypoxic insults were analyzed. For GFAP, in the neocortex, immunostaining revealed a significant decrease in strong staining for HH and TBI+HH groups compared with TBI group (P < .0001). For UCH-L1, the total immunostaining (6 regions of interest) reported a significant increase in strong staining (P < .0001) and decrease in weak staining (P < .0001) for the HH and TBI+HH groups compared with the Sham and TBI groups. For MMP-9, for the HH and TBI+HH groups, a significant increase in moderate (P < .0001) and weak staining (P < .0001) and a decrease in negative staining (P < .0001) compared with the Sham and TBI groups were observed. UCH-L1 and MMP-9 immunostainings increased after HH alone or HH combined with TBI compared with TBI alone. GFAP immunostaining decreased particularly in the neocortex after HH alone or HH combined with TBI compared with TBI alone. These three biomarkers could therefore be considered as potential biomarkers of HH insults independently of TBI.

Angioneurins - Key regulators of blood-brain barrier integrity during hypoxic and ischemic brain injury

The loss of blood-brain barrier (BBB) integrity leading to vasogenic edema and brain swelling is a common feature of hypoxic/ischemic brain diseases such as stroke, but is also central to the etiology of other CNS disorders. In the past decades, numerous proteins, belonging to the family of angioneurins, have gained increasing attention as potential therapeutic targets for ischemic stroke, but also other CNS diseases attributed to BBB dysfunction. Angioneurins encompass mediators that affect both neuronal and vascular function. Recently, increasing evidence has been accumulated that certain angioneurins critically determine disease progression and outcome in stroke among others through multifaceted effects on the compromised BBB. Here, we will give a concise overview about the family of angioneurins. We further describe the most important cellular and molecular components that contribute to structural integrity and low permeability of the BBB under steady-state conditions. We then discuss BBB alterations in ischemic stroke, and highlight underlying cellular and molecular mechanisms. For the most prominent angioneurin family members including vascular endothelial growth factors, angiopoietins, platelet-derived growth factors and erythropoietin, we will summarize current scientific literature from experimental studies in animal models, and if available from clinical trials, on the following points: (i) spatiotemporal expression of these factors in the healthy and hypoxic/ischemic CNS, (ii) impact of loss- or gain-of-function during cerebral hypoxia/ischemia for BBB integrity and beyond, and (iii) potential underlying molecular mechanisms. Moreover, we will highlight novel therapeutic strategies based on the activation of endogenous angioneurins that might improve BBB dysfuntion during ischemic stroke.

Protective Effect of Anthocyanin on Neurovascular Unit in Cerebral Ischemia/Reperfusion Injury in Rats

Treating cerebral ischemia continues to be a clinical challenge. Studies have shown that the neurovascular unit (NVU), as the central structural basis, plays a key role in cerebral ischemia. Here, we report that anthocyanin, a safe and natural antioxidant, could inhibit apoptosis and inflammation to protect NVU in rats impaired by middle cerebral artery occlusion/reperfusion (MCAO/R). Administration of anthocyanin significantly reduced infarct volume and neurological scores in MCAO/R rats. Anthocyanin could also markedly ameliorate cerebral edema and reduce the concentration of Evans blue (EB) by inhibiting MMP-9. Moreover, anthocyanin alleviated apoptotic injury resulting from MCAO/R through the regulation of Bcl-2 family proteins. The levels of inflammation-related molecules including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), which were over-expressed with MCAO/R, were decreased by anthocyanin. In addition, Nuclear factor-kappa B (NF-κB) and the NLRP3 inflammasome pathway might be involved in the anti-inflammatory effect of anthocyanin. In conclusion, anthocyanin could protect the NVU through multiple pathways, and play a protective role in cerebral ischemia/reperfusion injury.

A Precision Medicine Approach to Cerebral Edema and Intracranial Hypertension after Severe Traumatic Brain Injury: Quo Vadis?

PURPOSE OF REVIEW

Standard clinical protocols for treating cerebral edema and intracranial hypertension after severe TBI have remained remarkably similar over decades. Cerebral edema and intracranial hypertension are treated interchangeably when in fact intracranial pressure (ICP) is a proxy for cerebral edema but also other processes such as extent of mass lesions, hydrocephalus, or cerebral blood volume. A complex interplay of multiple molecular mechanisms results in cerebral edema after severe TBI, and these are not measured or targeted by current clinically available tools. Addressing these underpinnings may be key to preventing or treating cerebral edema and improving outcome after severe TBI.

RECENT FINDINGS

This review begins by outlining basic principles underlying the relationship between edema and ICP including the Monro-Kellie doctrine and concepts of intracranial compliance/elastance. There is a subsequent brief discussion of current guidelines for ICP monitoring/management. We then focus most of the review on an evolving precision medicine approach towards cerebral edema and intracranial hypertension after TBI. Personalization of invasive neuromonitoring parameters including ICP waveform analysis, pulse amplitude, pressure reactivity, and longitudinal trajectories are presented. This is followed by a discussion of cerebral edema subtypes (continuum of ionic/cytotoxic/vasogenic edema and progressive secondary hemorrhage). Mechanisms of potential molecular contributors to cerebral edema after TBI are reviewed. For each target, we present findings from preclinical models, and evaluate their clinical utility as biomarkers and therapeutic targets for cerebral edema reduction. This selection represents promising candidates with evidence from different research groups, overlap/inter-relatedness with other pathways, and clinical/translational potential. We outline an evolving precision medicine and translational approach towards cerebral edema and intracranial hypertension after severe TBI.

Neuroinflammatory mechanisms of blood-brain barrier damage in ischemic stroke

As part of the neurovascular unit, the blood-brain barrier (BBB) is a unique, dynamic regulatory boundary that limits and regulates the exchange of molecules, ions, and cells between the blood and the central nervous system. Disruption of the BBB plays an important role in the development of neurological dysfunction in ischemic stroke. Blood-borne substances and cells have restricted access to the brain due to the presence of tight junctions between the endothelial cells of the BBB. Following stroke, there is loss of BBB tight junction integrity, leading to increased paracellular permeability, which results in vasogenic edema, hemorrhagic transformation, and increased mortality. Thus, understanding principal mediators and molecular mechanisms involved in BBB disruption is critical for the development of novel therapeutics to treat ischemic stroke. This review discusses the current knowledge of how neuroinflammation contributes to BBB damage in ischemic stroke. Specifically, we provide an updated overview of the role of cytokines, chemokines, oxidative and nitrosative stress, adhesion molecules, matrix metalloproteinases, and vascular endothelial growth factor as well as the role of different cell types in the regulation of BBB permeability in ischemic stroke.

Emerging Roles of Sonic Hedgehog in Adult Neurological Diseases: Neurogenesis and Beyond

Sonic hedgehog (Shh), a member of the hedgehog (Hh) family, was originally recognized as a morphogen possessing critical characters for neural development during embryogenesis. Recently, however, Shh has emerged as an important modulator in adult neural tissues through different mechanisms such as neurogenesis, anti-oxidation, anti-inflammation, and autophagy. Therefore, Shh may potentially have clinical application in neurodegenerative diseases and brain injuries. In this article, we present some examples, including ours, to show different aspects of Shh signaling and how Shh agonists or mimetics are used to alter the neuronal fates in various disease models, both in vitro and in vivo. Other potential mechanisms that are discussed include alteration of mitochondrial function and anti-aging effect; both are critical for age-related neurodegenerative diseases. A thorough understanding of the protective mechanisms elicited by Shh may provide a rationale to design innovative therapeutic regimens for various neurodegenerative diseases.

Pathophysiology and treatment of cerebral edema in traumatic brain injury

Cerebral edema (CE) and resultant intracranial hypertension are associated with unfavorable prognosis in traumatic brain injury (TBI). CE is a leading cause of in-hospital mortality, occurring in >60% of patients with mass lesions, and ∼15% of those with normal initial computed tomography scans. After treatment of mass lesions in severe TBI, an important focus of acute neurocritical care is evaluating and managing the secondary injury process of CE and resultant intracranial hypertension. This review focuses on a contemporary understanding of various pathophysiologic pathways contributing to CE, with a subsequent description of potential targeted therapies. There is a discussion of identified cellular/cytotoxic contributors to CE, as well as mechanisms that influence blood-brain-barrier (BBB) disruption/vasogenic edema, with the caveat that this distinction may be somewhat artificial since molecular processes contributing to these pathways are interrelated. While an exhaustive discussion of all pathways with putative contributions to CE is beyond the scope of this review, the roles of some key contributors are highlighted, and references are provided for further details. Potential future molecular targets for treating CE are presented based on pathophysiologic mechanisms. We thus aim to provide a translational synopsis of present and future strategies targeting CE after TBI in the context of a paradigm shift towards precision medicine. This article is part of the Special Issue entitled "Novel Treatments for Traumatic Brain Injury".

Post-stroke mRNA expression profile of MMPs: effect of genetic deletion of MMP-12

Background and purpose

Recent reports from our laboratory demonstrated the post-ischaemic expression profile of various matrix metalloproteinases (MMPs) in rats and the detrimental role of MMP-12 in post-stroke brain damage. We hypothesise that the post-stroke dysregulation of MMPs is similar across species and that genetic deletion of MMP-12 would not affect the post-stroke expression of other MMPs. We tested our hypothesis by determining the pre-ischaemic and post-ischaemic expression profile of MMPs in wild-type and MMP-12 knockout mice.

Methods

Focal cerebral ischaemia was induced in wild-type and MMP-12 knockout mice by middle cerebral artery occlusion procedure by insertion of a monofilament suture. One hour after ischaemia, reperfusion was initiated by removing the monofilament. One day after reperfusion, ischaemic brain tissues from various groups of mice were collected, and total RNA was isolated and subjected to cDNA synthesis followed by PCR analysis.

Results

Although the post-stroke expression profile of MMPs in the ischaemic brain of mice is different from rats, there is a clear species similarity in the expression of MMP-12, which was found to be predominantly upregulated in both species. Further, the post-stroke induction or inhibition of various MMPs in MMP-12 knockout mice is different from their respective expression profile in wild-type mice. Moreover, the brain mRNA expression profile of various MMPs in MMP-12 knockout mice under normal conditions is also different to their expression in wild-type mice.

Conclusions

In the ischaemic brain, MMP-12 upregulates several fold higher than any other MMP. Mice derived with the genetic deletion of MMP-12 are constitutive and have altered MMP expression profile both under normal and ischaemic conditions.

Redox regulation of transient receptor potential channels in the endothelium

ROS and RNS are important mediators of signaling pathways in the endothelium. Specific members of the TRP superfamily of cation channels act as important Ca²⁺ influx pathways in endothelial cells and are involved in endothelium-dependent vasodilation, regulation of barrier permeability, and angiogenesis. ROS and RNS can modulate the activity of certain TRP channels mainly by modifying specific cysteine residues or by stimulating the production of second messengers. In this review, we highlight the recent literature describing redox regulation of TRP channel activity in endothelial cells as well as the physiological importance of these pathways and implication for cardiovascular diseases.

Blood brain barrier (BBB)-disruption in intracortical silicon microelectrode implants

Chronically implanted microelectrodes in the neural tissue elicit inflammatory responses that are time varying and have been shown to depend on multiple factors. Among these factors, blood brain barrier (BBB)-disruption has been hypothesized as one of the dominant factors resulting in electrode failure. A series of events that includes BBB and cell-membrane disruption occurs during electrode implantation that triggers multiple biochemical cascades responsible for microglial and astroglial activation, hemorrhage, edema, and release of pro-inflammatory neurotoxic cytokines that causes neuronal degeneration and dysfunction. Typically, microwire arrays and silicon probes are inserted slowly into the neural tissue whereas the silicon Utah MEAs (UMEA) are inserted at a high speed using a pneumatic inserter. In this work, we report the sequelae of electrode-implant induced cortical injury at various acute time points in UMEAs implanted in the brain tissue by quantifying the expression profile for key genes mediating the inflammatory response and tight junction (TJ) and adherens junction (AJ) proteins that form the BBB and are critical to the functioning of the BBB. Our results indicated upregulation of most pro-inflammatory genes relative to naïve controls for all time points. Expression levels for the genes that form the TJ and AJ were downregulated suggestive of BBB-dysfunction. Moreover, there was no significant difference between stab and implant groups suggesting the effects of UMEA insertion-related trauma in the brain tissue. Our results provide an insight into the physiological events related to neuroinflammation and BBB-disruption occurring at acute time-points following insertion of UMEAs.

Free Radical Damage in Ischemia-Reperfusion Injury: An Obstacle in Acute Ischemic Stroke after Revascularization Therapy

Acute ischemic stroke is a common cause of morbidity and mortality worldwide. Thrombolysis with recombinant tissue plasminogen activator and endovascular thrombectomy are the main revascularization therapies for acute ischemic stroke. However, ischemia-reperfusion injury after revascularization therapy can result in worsening outcomes. Among all possible pathological mechanisms of ischemia-reperfusion injury, free radical damage (mainly oxidative/nitrosative stress injury) has been found to play a key role in the process. Free radicals lead to protein dysfunction, DNA damage, and lipid peroxidation, resulting in cell death. Additionally, free radical damage has a strong connection with inducing hemorrhagic transformation and cerebral edema, which are the major complications of revascularization therapy, and mainly influencing neurological outcomes due to the disruption of the blood-brain barrier. In order to get a better clinical prognosis, more and more studies focus on the pharmaceutical and nonpharmaceutical neuroprotective therapies against free radical damage. This review discusses the pathological mechanisms of free radicals in ischemia-reperfusion injury and adjunctive neuroprotective therapies combined with revascularization therapy against free radical damage.

Transcranial Ultrasound Stimulation Improves Long-Term Functional Outcomes and Protects Against Brain Damage in Traumatic Brain Injury

The purpose of this study was to assess the long-term treatment efficacy of low-intensity pulsed ultrasound (LIPUS) on functional outcomes, brain edema, and the possible involvement of reactions in mice following traumatic brain injury (TBI). Mice subjected to controlled cortical impact injury received LIPUS treatment daily for a period of 4 weeks. The effects of LIPUS on edema were detected by MR imaging in the mouse brain at 148 days following TBI. Long-term functional outcomes of LIPUS stimulation were evaluated by behavioral analyses. One-way or two-way analysis of variance and Student's t test were used for statistical analyses, with a significant level of .05. Up to post-injury day 148, treatment with LIPUS significantly improved functional outcomes (all p < 0.05). LIPUS also significantly attenuated brain edema and neuronal death at day 148 after TBI (all p < 0.05). Furthermore, LIPUS reduced MMP9 activity, neutrophil infiltration, and microglial activation at day 1 or day 4 following TBI (all p < 0.05). Meanwhile, LIPUS increased the Bcl-2/Bax ratio and enhanced the phosphorylation of Bad and FOXO-1 at day 1 or day 4 following TBI (all p < 0.05). Almost 5 months of follow-up showed that the treatment efficacy of post-injury LIPUS stimulation on reduced brain edema and improved functional outcomes persisted over time after TBI. The neuroprotective effects of LIPUS are associated with a reduction of early inflammatory events and inhibition of apoptotic progression.

Baicalin Attenuates Blood-Brain Barrier Disruption and Hemorrhagic Transformation and Improves Neurological Outcome in Ischemic Stroke Rats with Delayed t-PA Treatment: Involvement of ONOO--MMP-9 Pathway

Tissue plasminogen activator (t-PA) has a restrictive therapeutic window within 4.5 h after ischemic stroke with the risk of hemorrhagic transformation (HT) and neurotoxicity when it is used beyond the time window. In the present study, we tested the hypothesis that baicalin, an active compound of medicinal plant, could attenuate HT in cerebral ischemia stroke with delayed t-PA treatment. Male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 4.5 h and then continuously received t-PA infusion (10 mg/kg) for 0.5 h and followed by 19-h reperfusion. Baicalin (50, 100, 150 mg/kg) was administrated via femoral vein at 4.5 h after MCAO cerebral ischemia. Delayed t-PA infusion significantly increased the mortality rate, induced HT, blood-brain barrier (BBB) damage, and apoptotic cell death in the ischemic brains and exacerbated neurological outcomes in cerebral ischemia-reperfusion rats at 24 h after MCAO cerebral ischemia. Co-treatment of baicalin significantly reduced the mortality rates, ameliorated the t-PA-mediated BBB disruption and HT. Furthermore, baicalin showed to directly scavenge peroxynitrite and inhibit MMP-9 expression and activity in the ischemic brains with the delayed t-PA treatment. Baicalin had no effect on the t-PA fibrinolytic function indicated by t-PA activity assay. Taken together, baicalin could attenuate t-PA-mediated HT and improve the outcomes of ischemic stroke treatment possibly via inhibiting peroxynitrite-mediated MMP-9 activation.

Prevention of hypertension-induced vascular dementia by Lactobacillus paracasei subsp. paracasei NTU 101-fermented products

CONTEXT

Numerous etiological studies have established positive clinical association between hypertension and vascular dementia (VaD). Lactobacillus paracasei subsp. paracasei NTU 101-fermented products have been shown to decrease vascular risk factors such as hypertension, atherosclerosis, hyperlipidemia and obesity.

OBJECTIVE

This study investigated the effect of ethanol extract of Lactobacillus paracasei subsp. paracasei NTU 101-fermented products (NTU101F) in hypertension-induced VaD in rats.

MATERIALS AND METHODS

Hypertension was promoted by subcutaneous injection of deoxycorticosterone acetate (DOCA, 25 mg/kg body weight/day, twice a week) and substitution of drinking water with 1.0% NaCl and 0.2% KCl. The NTU101F groups (0.5, 1.0, and 5.0) administered NTU101F at the concentrations 11, 22, and 110 mg/kg body weight/day, respectively, starting from day 51 day of DOCA-salt treatment. Morris water maze (MWM) was used for testing learning and memory. Different biochemical estimations were used to assess oxidative stress and inflammatory response in hippocampus.

RESULTS

Oral administration of NTU101F in DOCA-salt hypertension-induced VaD rats resulted in a significant decrease in blood pressure by 18.3-23.2% (p < 0.001), which was regulated by increasing eNOS density (about 3-fold) in the aorta, promoting NO production, and decreasing of matrix metallopeptidase 9 activity (about 2-fold) in the hippocampus, in addition to improve the kidney function and structure, decrease escape latency and increase the times spent in the target quadrant by 23.5-27.8% (p < 0.05).

CONCLUSION

Overall, our findings suggest that NTU101F could exert neuroprotection in the brain and attenuate hypertension-induced VaD.

Dexamethasone suppresses JMJD3 gene activation via a putative negative glucocorticoid response element and maintains integrity of tight junctions in brain microvascular endothelial cells

The blood-brain barrier (BBB) exhibits a highly selective permeability to support the homeostasis of the central nervous system (CNS). The tight junctions in the BBB microvascular endothelial cells seal the paracellular space to prevent diffusion. Thus, disruption of tight junctions results in harmful effects in CNS diseases and injuries. It has recently been demonstrated that glucocorticoids have beneficial effects on maintaining tight junctions in both in vitro cell and in vivo animal models. In the present study, we found that dexamethasone suppresses the expression of JMJD3, a histone H3K27 demethylase, via the recruitment of glucocorticoid receptor α (GRα) and nuclear receptor co-repressor (N-CoR) to the negative glucocorticoid response element (nGRE) in the upstream region of JMJD3 gene in brain microvascular endothelial cells subjected to TNFα treatment. The decreased JMJD3 gene expression resulted in the suppression of MMP-2, MMP-3, and MMP-9 gene activation. Dexamethasone also activated the expression of the claudin 5 and occludin genes. Collectively, dexamethasone attenuated the disruption of the tight junctions in the brain microvascular endothelial cells subjected to TNFα treatment. Therefore, glucocorticoids may help to preserve the integrity of the tight junctions in the BBB via transcriptional and post-translational regulation following CNS diseases and injuries.

Circulating tight junction proteins mirror blood-brain barrier integrity in leukaemia central nervous system metastasis

The aim of this study was to evaluate the clinical significance of circulating tight junction (TJ) proteins as biomarkers reflecting of leukaemia central nervous system (CNS) metastasis. TJs [claudin5 (CLDN5), occludin (OCLN) and ZO-1] concentrations were measured in serum and cerebrospinal fluid (CSF) samples obtained from 45 leukaemia patients. Serum ZO-1 was significantly higher (p < 0.05), but CSF ZO-1 levels were not significantly higher in the CNS leukaemia (CNSL) compared to the non-CNSL. The CNSL patients also had a lower CLDN5/ZO1 ratio in both serum and CSF than in non-CNSL patients (p < 0.05). The TJ index was negatively associated with WBC_CSF , ALB_CSF and BBB values in leukaemia patients. Among all of the parameters studied, CLDN5_CSF had the highest specificity in discriminating between CNSL and non-CNSL patients. Therefore, analysing serum and CSF levels of CLDN5, OCLN and the CLDN5/ZO1 ratio is valuable in evaluating the potential of leukaemia CNS metastasis. Copyright © 2016 John Wiley & Sons, Ltd.

Emerging concepts in sporadic cerebral amyloid angiopathy

Sporadic cerebral amyloid angiopathy is a common, well-defined small vessel disease and a largely untreatable cause of intracerebral haemorrhage and contributor to age-related cognitive decline. The term 'cerebral amyloid angiopathy' now encompasses not only a specific cerebrovascular pathological finding, but also different clinical syndromes (both acute and progressive), brain parenchymal lesions seen on neuroimaging and a set of diagnostic criteria-the Boston criteria, which have resulted in increasingly detected disease during life. Over the past few years, it has become clear that, at the pathophysiological level, cerebral amyloid angiopathy appears to be in part a protein elimination failure angiopathy and that this dysfunction is a feed-forward process, which potentially leads to worsening vascular amyloid-β accumulation, activation of vascular injury pathways and impaired vascular physiology. From a clinical standpoint, cerebral amyloid angiopathy is characterized by individual focal lesions (microbleeds, cortical superficial siderosis, microinfarcts) and large-scale alterations (white matter hyperintensities, structural connectivity, cortical thickness), both cortical and subcortical. This review provides an interdisciplinary critical outlook on various emerging and changing concepts in the field, illustrating mechanisms associated with amyloid cerebrovascular pathology and neurological dysfunction.