Blood-brain Barrier Dysfunction Research Articles

Fluid biomarkers of the neurovascular unit in cerebrovascular disease and vascular cognitive disorders: A systematic review and meta-analysis

BackgroundThe disruption of the neurovascular unit (NVU), which maintains the integrity of the blood brain barrier (BBB), has been identified as a critical mechanism in the development of cerebrovascular and neurodegenerative disorders. However, the understanding of the pathophysiological mechanisms linking NVU dysfunction to the disorders is incomplete, and reliable blood biomarkers to measure NVU dysfunction are yet to be established. This systematic review and meta-analysis aimed to identify biomarkers associated with BBB dysfunction in large vessel disease, small vessel disease (SVD) and vascular cognitive disorders (VCD). MethodsA literature search was conducted in PubMed, EMBASE, Scopus and PsychINFO to identify blood biomarkers related to dysfunction of the NVU in disorders with vascular pathologies published until 20 November 2023. Studies that assayed one or more specific markers in human serum or plasma were included. Quality of studies was assessed using the Newcastle-Ottawa Quality Assessment Scale. Effects were pooled and methodological heterogeneity examined using the random effects model. ResultsA total of 112 studies were included in this review. Where study numbers allowed, biomarkers were analysed using random effect meta-analysis for VCD (1 biomarker; 5 studies) and cerebrovascular disorders, including stroke and SVD (9 biomarkers; 29 studies) while all remaining biomarkers (n = 17 biomarkers; 78 studies) were examined through qualitative analysis. Results of the meta-analysis revealed that cerebrospinal fluid/serum albumin quotient (Q-Alb) reliably differentiates VCD patients from healthy controls (MD = 2.77; 95 % CI = 1.97–3.57; p < 0.0001) while commonly measured biomarkers of endothelial dysfunction (VEGF, VCAM-1, ICAM-1, vWF and E-selectin) and neuronal injury (NfL) were significantly elevated in vascular pathologies. A qualitative assessment of non-meta-analysed biomarkers revealed NSE, NfL, vWF, ICAM-1, VCAM-1, lipocalin-2, MMP-2 and MMP-9 levels to be upregulated in VCD, although these findings were not consistently replicated. ConclusionsThis review identifies several promising biomarkers of NVU dysfunction which require further validation. A panel of biomarkers representing multiple pathophysiological pathways may offer greater discriminative power in distinguishing possible disease mechanisms of VCD.

Progressive Disruption of Sphingosine-1-Phosphate Receptor 1 Correlates with Blood-Brain Barrier Leakage in A Rat Model of Chronic Hypoxic Hypoperfusion.

Endothelial dysfunction and blood-brain barrier (BBB) leakage have been suggested as a fundamental role in the development of cerebral small vessel disease (SVD) pathology. However, the molecular and cellular mechanisms that link cerebral hypoxic hypoperfusion and BBB disruption remain elusive. Sphingosine-1-phosphate (S1P) regulates the BBB integrity by binding to its receptor isoform 1 (S1PR1) on endothelial cells. This study tested the hypothesis that hypoxic hypoperfusion triggers capillary endothelial S1PR1 disruption, which compromises BBB integrity and leads to SVD-related neuropathological changes, using a chronic hypoxic hypoperfusion model with BBB dysfunction. Spontaneously hypertensive rat stroke-prone underwent unilateral carotid artery occlusion (UCAO) followed by a Japanese permissive diet (JPD) for up to 9 weeks. Selective S1PR1 agonist SEW2871 was used to activate S1PR1. Significant progressive reduction of S1PR1 was detected in rat brains from 4 to 9 weeks following UCAO/JPD onset, which was also detected in cerebral vasculature in human SVD. S1PR1 activation by SEW2871 significantly reduced lesions in both white and grey matter and ameliorated cerebral blood flow. SEW2871 reversed the loss of endothelial S1PR1 and tight junction proteins, and significantly attenuated UCAO/JPD induced accumulation of neuronal phosphorylated tau. This protective role of SEW2871 is associated with promotion of Akt phosphorylation and inhibition of S1PR2/Erk1/2 activation. Our data suggest S1PR1 signalling as a potential molecular mechanistic basis that links hypoxic hypoperfusion with BBB damage in the neuropathological cascades in SVD. The reversal of BBB disruption through pharmacological intervention of S1PR1 signalling likely reveals a novel therapeutic target for SVD.

Hope for vascular cognitive impairment: Ac-YVAD-cmk as a novel treatment against white matter rarefaction.

Vascular cognitive impairment (VCI) is the second leading cause of dementia with limited treatment options, characterised by cerebral hypoperfusion-induced white matter rarefaction (WMR). Subcortical VCI is the most common form of VCI, but the underlying reasons for region susceptibility remain elusive. Recent studies employing the bilateral cortical artery stenosis (BCAS) method demonstrate that various inflammasomes regulate white matter injury and blood-brain barrier dysfunction but whether caspase-1 inhibition will be beneficial remains unclear. To address this, we performed BCAS on C57/BL6 mice to study the effects of Ac-YVAD-cmk, a caspase-1 inhibitor, on the subcortical and cortical regions. Cerebral blood flow (CBF), WMR, neuroinflammation and the expression of tight junction-related proteins associated with blood-brain barrier integrity were assessed 15 days post BCAS. We observed that Ac-YVAD-cmk restored CBF, attenuated BCAS-induced WMR and restored subcortical myelin expression. Within the subcortical region, BCAS activated the NLRP3/caspase-1/interleukin-1beta axis only within the subcortical region, which was attenuated by Ac-YVAD-cmk. Although we observed that BCAS induced significant increases in VCAM-1 expression in both brain regions that were attenuated with Ac-YVAD-cmk, only ZO-1 and occludin were observed to be significantly altered in the subcortical region. Here we show that caspase-1 may contribute to subcortical regional susceptibility in a mouse model of VCI. In addition, our results support further investigations into the potential of Ac-YVAD-cmk as a novel treatment strategy against subcortical VCI and other conditions exhibiting cerebral hypoperfusion-induced WMR.

Aging Increases Hypoxia-Induced Endothelial Permeability and Blood-Brain Barrier Dysfunction by Upregulating Arginase-II.

Increased endothelial permeability plays an important role in blood-brain barrier (BBB) dysfunction and is implicated in neuronal injury in many diseased conditions. BBB disruption is primarily determined by dysfunction of endothelial cell-cell junctions. Deprivation of oxygen supply or hypoxia, a common feature of a variety of human diseases, is a major risk factor for BBB disruption. The molecular regulatory mechanisms of hypoxia-induced BBB dysfunction remain incompletely understood. The mitochondrial enzyme, arginase type II (Arg-II), has been shown to promote endothelial dysfunction. However, its role in hypoxia-induced BBB dysfunction has not been explored. In the C57BL/6J mouse model, hypoxia (8% O2, 24 hours) augments vascular Arg-II in the hippocampus, decreases cell-cell junction protein levels of Zonula occludens-1 (ZO-1), occludin, and CD31 in endothelial cells, increases BBB leakage in the brain in old mice (20 to 24 months) but not in young animals (3 to 6 months). These effects of hypoxia in aging are suppressed in arg-ii-/- mice. Moreover, the age-associated vulnerability of endothelial integrity to hypoxia is demonstrated in senescent human brain microvascular endothelial cell (hCMEC/D3) culture model. Further results in the cell culture model show that hypoxia augments Arg-II, decreases ZO-1 and occludin levels, and increases endothelial permeability, which is prevented by arg-ii gene silencing or by inhibition of mitochondrial reactive oxygen species (mtROS) production. Our study demonstrates an essential role of Arg-II in increased endothelial permeability and BBB dysfunction by promoting mtROS generation, resulting in decreased endothelial cell-cell junction protein levels under hypoxic conditions particularly in aging.

Neuroinflammation, blood-brain barrier dysfunction, hippocampal atrophy and delayed neurodevelopment: Contributions for a rat model of congenital Zika syndrome

The congenital Zika syndrome (CZS) has been characterized as a set of several brain changes, such as reduced brain volume and subcortical calcifications, in addition to cognitive deficits. Microcephaly is one of the possible complications found in newborns exposed to Zika virus (ZIKV) during pregnancy, although it is an impacting clinical sign. This study aimed to investigate the consequences of a model of congenital ZIKV infection by evaluating the histopathology, blood-brain barrier, and neuroinflammation in pup rats 24 h after birth, and neurodevelopment of the offspring. Pregnant rats were inoculated subcutaneously with ZIKV-BR at the dose 1 × 107 plaque-forming unit (PFU mL-1) of ZIKV isolated in Brazil (ZIKV-BR) on gestational day 18 (G18). A set of pups, 24 h after birth, was euthanized. The brain was collected and later evaluated for the histopathology of brain structures through histological analysis. Additionally, analyses of the blood-brain barrier were conducted using western blotting, and neuroinflammation was assessed using ELISA. Another set of animals was evaluated on postnatal days 3, 6, 9, and 12 for neurodevelopment by observing the developmental milestones. Our results revealed hippocampal atrophy in ZIKV animals, in addition to changes in the blood-brain barrier structure and pro-inflammatory cytokines expression increase. Regarding neurodevelopment, a delay in important reflexes during the neonatal period in ZIKV animals was observed. These findings advance the understanding of the pathophysiology of CZS and contribute to enhancing the rat model of CZS.

Cardiac functional and structural impairments, endothelial apoptosis and blood-brain barrier dysfunction in models of cerebrovascular amyloidosis in the presence or absence of hyperhomocysteinemia

Cardiac functional and structural impairments, endothelial apoptosis and blood-brain barrier dysfunction in models of cerebrovascular amyloidosis in the presence or absence of hyperhomocysteinemia

Dysregulation of Ion Channels and Transporters and Blood-Brain Barrier Dysfunction in Alzheimer's Disease and Vascular Dementia.

The blood-brain barrier (BBB) plays a critical role in maintaining ion and fluid homeostasis, essential for brain metabolism and neuronal function. Regulation of nutrient, water, and ion transport across the BBB is tightly controlled by specialized ion transporters and channels located within its unique cellular components. These dynamic transport processes not only influence the BBB's structure but also impact vital signaling mechanisms, essential for its optimal function. Disruption in ion, pH, and fluid balance at the BBB is associated with brain pathology and has been implicated in various neurological conditions, including stroke, epilepsy, trauma, and neurodegenerative diseases such as Alzheimer's disease (AD). However, knowledge gaps exist regarding the impact of ion transport dysregulation on BBB function in neurodegenerative dementias. Several factors contribute to this gap: the complex nature of these conditions, historical research focus on neuronal mechanisms and technical challenges in studying the ion transport mechanisms in in vivo models and the lack of efficient in vitro BBB dementia models. This review provides an overview of current research on the roles of ion transporters and channels at the BBB and poses specific research questions: 1) How are the expression and activity of key ion transporters altered in AD and vascular dementia (VaD); 2) Do these changes contribute to BBB dysfunction and disease progression; and 3) Can restoring ion transport function mitigate BBB dysfunction and improve clinical outcomes. Addressing these gaps will provide a greater insight into the vascular pathology of neurodegenerative disorders.

Neuroinvasion of emerging and re-emerging arboviruses: A scoping review.

Arboviruses are RNA viruses and some have the potential to cause neuroinvasive disease and are a growing threat to global health. Our objective is to identify and map all aspects of arbovirus neuroinvasive disease, clarify key concepts, and identify gaps within our knowledge with appropriate future directions related to the improvement of global health. Sources of Evidence: A scoping review of the literature was conducted using PubMed, Scopus, ScienceDirect, and Hinari. Eligibility Criteria: Original data including epidemiology, risk factors, neurological manifestations, neuro-diagnostics, management, and preventive measures related to neuroinvasive arbovirus infections was obtained. Sources of evidence not reporting on original data, non-English, and not in peer-reviewed journals were removed. Charting Methods: An initial pilot sample of 30 abstracts were reviewed by all authors and a Cohen's kappa of κ = 0.81 (near-perfect agreement) was obtained. Records were manually reviewed by two authors using the Rayyan QCRI software. A total of 171 records were included. A wide array of neurological manifestations can occur most frequently, including parkinsonism, encephalitis/encephalopathy, meningitis, flaccid myelitis, and Guillain-Barré syndrome. Magnetic resonance imaging of the brain often reveals subcortical lesions, sometimes with diffusion restriction consistent with acute ischemia. Vertical transmission of arbovirus is most often secondary to the Zika virus. Neurological manifestations of congenital Zika syndrome, include microcephaly, failure to thrive, intellectual disability, and seizures. Cerebrospinal fluid analysis often shows lymphocytic pleocytosis, elevated albumin, and protein consistent with blood-brain barrier dysfunction. Arbovirus infection with neurological manifestations leads to increased morbidity and mortality. Risk factors for disease include living and traveling in an arbovirus endemic zone, age, pregnancy, and immunosuppressed status. The management of neuroinvasive arbovirus disease is largely supportive and focuses on specific neurological complications. There is a need for therapeutics and currently, management is based on disease prevention and limiting zoonosis.

Discovery of plasma biomarkers related to blood-brain barrier dysregulation in Alzheimer's disease.

Blood-based biomarkers are quantitative, non-invasive diagnostic tools. This study aimed to identify candidate biomarkers for Alzheimer's disease (AD) using publicly available omics datasets, using the hypothesis that with blood-brain barrier dysfunction in AD, brain-synthesized proteins can leak into plasma for detection. Differential abundance results of plasma and brain proteomic datasets were integrated to obtain a list of potential biomarkers. Biological validity was investigated with intercellular communication and gene regulatory analyses on brain single-cell transcriptomics data. Five proteins (APOD, B2M, CFH, CLU, and C3) fit biomarker criteria. 4 corresponding transcripts (APOD, B2M, CLU, and C3) were overexpressed in AD astrocytes, mediated by AD-related dysregulations in transcription factors regulating neuroinflammation. Additionally, CLU specifically induced downstream expression of neuronal death genes. In conclusion, a 5-protein panel is shown to effectively identify AD patients, with evidence of disease specificity and biological validity. Future research should investigate the mechanism of protein leakage through the blood-brain barrier.

Long-Term Alcohol Exposure Aggravates Ischemic Stroke-Induced Damage by Promoting Pericyte NLRP3 Inflammasome Activation via Pre-Activating the TLR4/NF-κB Pathway in Rats.

Ischemic stroke (IS) is one of the leading causes of death and disability in the world, and alcohol consumption has been gaining attention as an independent risk factor for IS. Blood-brain barrier (BBB) dysfunction and neuroinflammation are the core of cerebral ischemia/reperfusion (I/R) injury, and pericytes play a crucial role in the structure and function. This study is to explore the effects of long-term alcohol consumption on IS and the potential mechanisms of pericytes. Rat models of long-term alcohol intake followed by transient middle cerebral artery occlusion stroke (EtOH+tMCAO) and cell models of oxygen-glucose deprivation/reoxygenation (OGD/R) with alcohol pre-treatment were constructed. Worsened infarct volume, neurological scores, and BBB disruption were observed in the EtOH+tMCAO group compared with the tMCAO group, and immunofluorescence staining showed increased pericytes NLPR3 inflammasome activation at the ischemic penumbra. In vitro, pericyte mortality and LDH release elevated pre-treated by alcohol after OGD/R, and amplified expression of NLRP3 inflammasome was detected by Western blotting and qPCR. Alcohol pre-treatment activated the TLR4/NF-κB pathway, and transfecting pericytes with TLR4-small interfering RNA (siRNA) to block TLR4 signaling markedly restrained NLRP3 inflammasome over-activation. Injecting TAK-242 in rats alleviated neurological impairment caused by alcohol. Long-term alcohol pre-treatment aggravated ischemic stroke-induced brain damage by activating NLRP3 inflammasome via TLR4/NF-κB signaling pathway in the pericytes.

Establishment of a novel amyotrophic lateral sclerosis patient (TARDBP N345K/+)-derived brain microvascular endothelial cell model reveals defective Wnt/β-catenin signaling: investigating diffusion barrier dysfunction and immune cell interaction.

Amyotrophic lateral sclerosis (ALS) is a major neurodegenerative disease for which there is currently no curative treatment. The blood-brain barrier (BBB), multiple physiological functions formed by mainly specialized brain microvascular endothelial cells (BMECs), serves as a gatekeeper to protect the central nervous system (CNS) from harmful molecules in the blood and aberrant immune cell infiltration. The accumulation of evidence indicating that alterations in the peripheral milieu can contribute to neurodegeneration within the CNS suggests that the BBB may be a previously overlooked factor in the pathogenesis of ALS. Animal models suggest BBB breakdown may precede neurodegeneration and link BBB alteration to the disease progression or even onset. However, the lack of a useful patient-derived model hampers understanding the pathomechanisms of BBB dysfunction and the development of BBB-targeted therapies. In this study, we differentiated BMEC-like cells from human induced pluripotent stem cells (hiPSCs) derived from ALS patients to investigate BMEC functions in ALS patients. TARDBP N345K/+ carrying patient-derived BMEC-like cells exhibited increased permeability to small molecules due to loss of tight junction in the absence of neurodegeneration or neuroinflammation, highlighting that BMEC abnormalities in ALS are not merely secondary consequences of disease progression. Furthermore, they exhibited increased expression of cell surface adhesion molecules like ICAM-1 and VCAM-1, leading to enhanced immune cell adhesion. BMEC-like cells derived from hiPSCs with other types of TARDBP gene mutations (TARDBP K263E/K263E and TARDBP G295S/G295S) introduced by genome editing technology did not show such BMEC dysfunction compared to the isogenic control. Interestingly, transactive response DNA-binding protein 43 (TDP-43) was mislocalized to cytoplasm in TARDBP N345K/+ carrying model. Wnt/β-catenin signaling was downregulated in the ALS patient (TARDBP N345K/+)-derived BMEC-like cells and its activation rescued the leaky barrier phenotype and settled down VCAM-1 expressions. These results indicate that TARDBP N345K/+ carrying model recapitulated BMEC abnormalities reported in brain samples of ALS patients. This novel patient-derived BMEC-like cell is useful for the further analysis of the involvement of vascular barrier dysfunctions in the pathogenesis of ALS and for promoting therapeutic drug discovery targeting BMEC.

Angiotensin II, blood-brain barrier permeability, and microglia interplay during the transition from pre-to hypertensive phase in spontaneously hypertensive rats.

Hypertension is characterized by upregulation of the renin-angiotensin system, increased blood-brain barrier (BBB) permeability, microglia activation within autonomic nuclei, and an intense sympathoexcitation. There is no information on the interplay of these events during the development of neurogenic hypertension. We sought to identify the interaction and time-course changes of Ang II availability, barrier dysfunction, microglia activation, and autonomic imbalance within autonomic areas during the development of neurogenic hypertension. Sequential changes of hemodynamic/autonomic parameters, BBB permeability, microglia structure/density (IBA-1), and angiotensin II (Ang II) immunofluorescence were evaluated within the paraventricular hypothalamic nucleus, nucleus of the solitary tract, and rostral ventrolateral medulla of Wistar and spontaneously hypertensive rats (SHRs) aged 4 weeks, 5 weeks, 6 weeks, 8 weeks, and 12weeks. The somatosensory cortex and hypoglossal nucleus were also analyzed as non-autonomic control areas. Increased brain Ang II availability (4th-5thweek) was the first observed change, followed by the incipient BBB leakage and increased microglia density (6thweek). From the 5th-6thweeks on, BBB leakage, Ang II, and IBA-1 densities increased continuously, allowing a parallel increase in both Ang II-microglia colocalization and the transition of microglial cells from highly ramified in the basal surveillant condition (4th-5thweek) to shorter process arbors, fewer endpoints, and enlarged soma in the disease-associate condition (6th week to the 12th week). Simultaneously with increased Ang II-microglia colocalization and microglia morphologic phenotypic changes, sympathetic activity and pressure variability increased, autonomic control deteriorated, and blood pressure increased. These responses were not specific for autonomic nuclei but also occurred at a lower magnitude in the somatosensory cortex and hypoglossal nucleus, indicating the predominance of hypertension-induced effects on autonomic areas. No changes were observed in age-matched controls where Ang II density did not change. Brain Ang II density is the initial stimulus to drive coordinated changes in BBB permeability and microglial reactivity. Increased BBB dysfunction allows access of plasma Ang II and increases its local availability and the colocalization and activation of microglial cells. It is a potent stimulus to augments vasomotor sympathetic activity, autonomic imbalance, and pressure elevation during the establishment of hypertension.

Clinical features and immunotherapy outcomes in antibody-negative autoimmune encephalitis: a retrospective case-control study.

This study aimed to compare clinical features, laboratory findings, and immunotherapy responses between antibody-positive and antibody-negative Autoimmune encephalitis (AE) patients. A retrospective analysis of clinical data from 60 AE patients (33 antibody-positive, 27 antibody-negative) diagnosed at Zhongshan Hospital of Xiamen University between January 1, 2016, and March 1, 2024 was conducted. Disease severity and treatment response were assessed using the modified Rankin Scale (mRS) and the Clinical Assessment Scale for Autoimmune Encephalitis (CASE). Antibody-positive AE patients more frequently presented with multiple symptoms (≥4 symptoms: 39.4% vs. 14.8%, p = 0.036). They demonstrated significantly elevated serum IgG concentrations (p = 0.010) and cerebrospinal fluid (CSF) leukocyte counts (p = 0.014). Conversely, antibody-negative AE patients presented with higher CSF total protein levels (p = 0.025) and albumin quotients (p = 0.018), indicative of more severe blood-brain barrier disruption. Antibody-positive AE patients more frequently received combination first-line immunotherapy (75.8% vs. 48.1%, p = 0.027) and exhibited superior treatment outcomes (90.9% vs. 70%, p = 0.022). Among critically ill patients (peak mRS score: 4-5), improvement in CASE scores was markedly greater in the antibody-positive cohort (median: 4.50 vs. 1.00, p = 0.024). Antibody-positive AE patients manifested a more diverse symptom spectrum, elevated serum IgG concentrations and CSF leukocyte counts, and superior responses to immunotherapy. In contrast, antibody-negative AE patients demonstrated more severe blood-brain barrier dysfunction, as evidenced by higher CSF total protein concentrations and albumin quotients.

Wnt7a Decreases Brain Endothelial Barrier Function Via β-Catenin Activation

The blood-brain barrier consists of tightly connected endothelial cells protecting the brain’s microenvironment from the periphery. These endothelial cells are characterized by specific tight junction proteins such as Claudin-5 and Occludin, forming the endothelial barrier. Disrupting these cells might lead to blood-brain barrier dysfunction. The Wnt/β-catenin signaling pathway can regulate the expression of these tight junction proteins and subsequent barrier permeability. The aim of this study was to investigate the in vitro effects of Wnt7a mediated β-catenin signaling on endothelial barrier integrity. Mouse brain endothelial cells, bEnd.3, were treated with recombinant Wnt7a protein or XAV939, a selective inhibitor of Wnt/β-catenin mediated transcription to modulate the Wnt signaling pathway. The involvement of Wnt/HIF1α signaling was investigated by inhibiting Hif1α signaling with Hif1α siRNA. Wnt7a stimulation led to activation and nuclear translocation of β-catenin, which was inhibited by XAV939. Wnt7a stimulation decreased Claudin-5 expression mediated by β-catenin and decreased endothelial barrier formation. Wnt7a increased Hif1α and Vegfa expression mediated by β-catenin. However, Hif1α signaling pathway did not regulate tight junction proteins Claudin-5 and Occludin. Our data suggest that Wnt7a stimulation leads to a decrease in tight junction proteins mediated by the nuclear translocation of β-catenin, which hampers proper endothelial barrier formation. This process might be crucial in initiating endothelial cell proliferation and angiogenesis. Although HIF1α did not modulate the expression of tight junction proteins, it might play a role in brain angiogenesis and underlie pathogenic mechanisms in Wnt/HIF1α signaling in diseases such as cerebral small vessel disease.

Kaempferol-3-O-(2″-O-galloyl-β-D-glucopyranoside): a novel neuroprotective agent from Diospryros kaki against cerebral ischemia-induced brain injury.

Our previous study demonstrated neuroprotective and therapeutic effects of a standardized flavonoid extract from leaves of Diospyros kaki L.f. (DK) on middle cerebral artery occlusion-and-reperfusion (MCAO/R)-induced brain injury and its underlying mechanisms. This study aimed to clarify flavonoid components responsible for the effects of DK using in vitro and in vivo transient brain ischemic models. Organotypic hippocampal slice cultures (OHSCs) subjected to oxygen- and glucose-deprivation (OGD) were performed to evaluate in vitro neuroprotective activity of DK extract and nine isolated flavonoid components. MCAO/R mice were employed to elucidate in vivo neuroprotective effects of the flavonoid component that exhibited the most potent neuroprotective effect in OHSCs. DK extract and seven flavonoids [quercetin, isoquercetin, hyperoside, quercetin-3-O-(2″-O-galloyl-β-D-galactopyranoside), kaempferol, astragalin, and kaempferol-3-O-(2″-O-galloyl-β-D-glucopyranoside) compound (9)] attenuated OGD-induced neuronal cell damage and compound (9) possessed the most potent neuroprotective activity in OHSCs. The MCAO/R mice showed cerebral infarction, massive weight loss, characteristic neurological symptoms, and deterioration of neuronal cells in the brain. Compound (9) and a reference drugs, edaravone, significantly attenuated these physical and neurological impairments. Compound (9) mitigated the blood-brain barrier dysfunction and the change of glutathione and malondialdehyde content in the MCAO mouse brain. Edaravone suppressed the oxidative stress but did not significantly affect the blood-brain barrier permeability. The present results indicated that compound (9) is a flavonoid constituent of DK with a potent neuroprotective activity against transient ischemia-induced brain damage and this action, at least in part, via preservation of blood-brain barrier integrity and suppression of oxidative stress caused by ischemic insult.

C-kit controls blood-brain barrier permeability by regulating caveolae-mediated transcytosis after chronic cerebral hypoperfusion

Blood-brain barrier (BBB) dysfunction plays a pivotal role in the pathology of chronic cerebral hypoperfusion (CCH)-related neurodegenerative diseases. Continuous endothelial cells (EC) that line the blood vessels of the brain are important components of the BBB to strictly control the flow of substances and maintain the homeostatic environment of the brain. However, the molecular mechanisms from the perspective of EC-induced BBB dysfunction after CCH are largely unknown. In this study, the BBB function was assessed using immunostaining and transmission electron microscopy. The EC dysfunction profile was screened by using EC enrichment followed by RNA sequencing. After identified the key EC dysfunction factor, C-kit, we used the C-kit inhibition drug (imatinib) and C-kit down-regulation method (AAV-BR1-C-kit shRNA) to verify the role of C-kit on BBB integrity and EC transcytosis after CCH. Furthermore, we also activated C-kit with stem cell factor (SCF) to observe the effects of C-kit on BBB following CCH. We explored that macromolecular proteins entered the brain mainly through EC transcytosis after CCH and caused neuronal loss. Additionally, we identified receptor tyrosine kinase C-kit as a key EC dysfunction molecule. Furthermore, the pharmacological inhibition of C-kit with imatinib counteracted BBB leakage by reducing caveolae-mediated transcytosis. Moreover, treatment with AAV-BR1-C-kit shRNA, which targets brain EC to inhibit C-kit expression, also ameliorated BBB leakage by reducing caveolae-mediated transcytosis. Furthermore, the SCF increased the permeability of the BBB by actively increasing caveolae-mediated transcytosis. This study provides evidence that C-kit is a key BBB permeability regulator through caveolae-mediated transcytosis in EC after CCH.

Rebuilding insight into the pathophysiology of Alzheimer's disease through new blood-brain barrier models.

The blood-brain barrier is a unique function of the microvasculature in the brain parenchyma that maintains homeostasis in the central nervous system. Blood-brain barrier breakdown is a common pathology in various neurological diseases, such as Alzheimer's disease, stroke, multiple sclerosis, and Parkinson's disease. Traditionally, it has been considered a consequence of neuroinflammation or neurodegeneration, but recent advanced imaging techniques and detailed studies in animal models show that blood-brain barrier breakdown occurs early in the disease process and may precede neuronal loss. Thus, the blood-brain barrier is attractive as a potential therapeutic target for neurological diseases that lack effective therapeutics. To elucidate the molecular mechanism underlying blood-brain barrier breakdown and translate them into therapeutic strategies for neurological diseases, there is a growing demand for experimental models of human origin that allow for functional assessments. Recently, several human induced pluripotent stem cell-derived blood-brain barrier models have been established and various in vitro blood-brain barrier models using microdevices have been proposed. Especially in the Alzheimer's disease field, the human evidence for blood-brain barrier dysfunction has been demonstrated and human induced pluripotent stem cell-derived blood-brain barrier models have suggested the putative molecular mechanisms of pathological blood-brain barrier. In this review, we summarize recent evidence of blood-brain barrier dysfunction in Alzheimer's disease from pathological analyses, imaging studies, animal models, and stem cell sources. Additionally, we discuss the potential future directions for blood-brain barrier research.

LncRNA MALAT1 and Ischemic Stroke: Pathogenesis and Opportunities.

Ischemic stroke (IS) stands as a prominent cause of mortality and long-term disability around the world. It arises primarily from a disruption in cerebral blood flow, inflicting severe neural injuries. Hence, there is a pressing need to comprehensively understand the intricate mechanisms underlying IS and identify novel therapeutic targets. Recently, long noncoding RNAs (lncRNAs) have emerged as a novel class of regulatory molecules with the potential to attenuate pathogenic mechanisms following IS. Among these lncRNAs, MALAT1 (metastasis-associated lung adenocarcinoma transcript 1) has been extensively studied due to its involvement in the pathophysiological processes of IS. In this review, we provide an in-depth analysis of the essential role of MALAT1 in the development and progression of both pathogenic and protective mechanisms following IS. These mechanisms include oxidative stress, neuroinflammation, cell death signaling, blood brain barrier dysfunction, and angiogenesis. Furthermore, we summarize the impact of MALAT1 on the susceptibility and severity of IS. This review highlights the potential risks associated with the therapeutic use of MALAT1 for IS, which are attributable to the stimulatory action of MALAT1 on ischemia/reperfusion injury. Ultimately, this review sheds light on the potential molecular mechanisms and associated signaling pathways underlying MALAT1 expression post-IS, with the aim of uncovering potential therapeutic targets.

Inhibiting Caveolin-1-Related Akt/mTOR Signaling Pathway Protects Against N-methyl-D-Aspartate Receptor Activation-Mediated Dysfunction of Blood–Brain Barrier in vitro

BackgroundThe aim of this study was to further explore the role of caveolin-1 (Cav-1) related Akt/mTOR signaling pathway in blood brain barrier (BBB) dysfunction caused by NMDAR activation.MethodsThe cell localization of NMDAR GluN1 subunit and Cav-1 was observed on human brain microvascular HBEC-5i cells after immunofluorescence double staining. The transendothelial resistance (TEER) of BBB in vitro was measured by Millicell-ERS cell resistance meter. Sodium fluorescein (SF) was used to measure the permeability of BBB in vitro. A stable Cav-1-silenced HBEC-5i cell line was established by infecting the cells with a lentivirus encoding Cav-1 shRNA. The changes of the protein and mRNA of MMP9 and Occludin induced by NMDA were detected by Western blot (WB) and real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), respectively. The phosphorylated proteins of Cav-1, Akt, and mTOR were detected by WB.ResultsNMDAR GluN1 was expressed in the cytoplasm and part of the cell membrane of the HBEC-5i cell line. NMDAR activation decreased TEER and increased the SF of BBB in vitro. HBEC-5i cells incubated with NMDA enhanced the phosphorylation of Cav-1, Akt, and mTOR, also promoting the expression of MMP9 along with the degradation of Occludin. These effects could be reversed by pretreatment with NMDAR antagonist (MK801) or Cav-1 antagonist (Daidzein), or Akt antagonist (LY294002), respectively. Further silencing Cav-1 with LV-Cav-1-RNAi also played a similar protective effect.ConclusionCaveolin-1 (Cav-1) related Akt/mTOR signaling probably contributes to BBB dysfunction by activating NMDAR on human brain microvascular cells.

MiRNA-ome plasma analysis unveils changes in blood–brain barrier integrity associated with acute liver failure in rats

BackgroundHepatic encephalopathy (HE) symptoms associated with liver insufficiency are linked to the neurotoxic effects of ammonia and other toxic metabolites reaching the brain via the blood–brain barrier (BBB), further aggravated by the inflammatory response. Cumulative evidence documents that the non-coding single-stranded RNAs, micro RNAs (miRs) control the BBB functioning. However, miRs’ involvement in BBB breakdown in HE is still underexplored. Here, we hypothesized that in rats with acute liver failure (ALF) or rats subjected to hyperammonemia, altered circulating miRs affect BBB composing proteins.MethodsTransmission electron microscopy was employed to delineate structural alterations of the BBB in rats with ALF (thioacetamide (TAA) intraperitoneal (ip.) administration) or hyperammonemia (ammonium acetate (OA) ip. administration). The BBB permeability was determined with Evans blue dye and sodium fluorescein assay. Plasma MiRs were profiled by Next Generation Sequencing (NGS), followed by in silico analysis. Selected miRs, verified by qRT-PCR, were examined in cultured rat brain endothelial cells. Targeted protein alterations were elucidated with immunofluorescence, western blotting, and, after selected miR mimics transfection, through an in vitro resistance measurement.ResultsChanges in BBB structure and increased permeability were observed in the prefrontal cortex of TAA rats but not in the brains of OA rats. The NGS results revealed divergently changed miRNA-ome in the plasma of both rat models. The in silico analysis led to the selection of miR-122-5p and miR-183-5p with their target genes occludin and integrin β1, respectively, as potential contributors to BBB alterations. Both proteins were reduced in isolated brain vessels and cortical homogenates in TAA rats. We documented in cultured primary brain endothelial cells that ammonia alone and, in combination with TNFα increases the relative expression of NGS-selected miRs with a less pronounced effect of TNFα when added alone. The in vitro study also confirmed miR-122-5p-dependent decrease in occludin and miR-183-5p-related reduction in integrin β1 expression.ConclusionThis work identified, to our knowledge for the first time, potential functional links between alterations in miRs residing in brain endothelium and BBB dysfunction in ALF.