Dexamethasone induces the expression of metalloproteinase inhibitor TIMP-1 in the murine cerebral vascular endothelial cell line cEND

Adrenocorticotropic hormone therapy alters Q-albumin ratios in patients with infantile epileptic spasms syndrome of unknown etiology

PURPOSE

Infantile epileptic spasms syndrome (IESS) with epileptic spasms as the main seizure type, is treated with adrenocorticotropic hormone (ACTH). This study, for the first time, examines the effects of epileptic spasms and ACTH on blood-brain barrier (BBB) permeability in patients with IESS of unknown etiology.

METHODS

We prospectively evaluated the changes in BBB permeability in patients with IESS of unknown etiology at the Saitama Children's Medical Center between February 2012 and February 2024. We compared the levels of serum-albumin, cerebrospinal fluid (CSF)-albumin, Q-albumin, and CSF-neuron-specific enolase (NSE) before and after ACTH therapy. We also assessed the correlation between the frequency of epileptic spasms and these markers.

RESULTS

Overall, 16 patients with IESS (8 males) were included in the study. The median age at IESS onset was 5 (range, 2-9) months. The median duration between the epileptic spasms onset and the serum and CSF sample examination before ACTH therapy was 26 (range, 1-154) days. After ACTH therapy, CSF-albumin and Q-albumin levels significantly decreased (CSF-albumin: 13.5 (9.0-32.0) mg/dL vs 11.0 (7.0-19.0) mg/dL, p = 0.001. Q-albumin: 3.7× 10-3 (2.2 × 10-3-7.3 × 10-3) vs 2.8× 10-3 (1.9 × 10-3-4.5 × 10-3), p = 0.003). No correlation was observed between the epileptic spasms frequency and levels of serum-albumin, CSF-albumin, Q-albumin, and CSF-NSE (Spearman's coefficient: r = 0.291, r = 0.141, r = 0.094, and r = -0.471, respectively).

CONCLUSION

ACTH therapy is one of the factors that play a role in restoring BBB permeability in patients with IESS of unknown etiology. Our findings may be useful in elucidating the mechanism of ACTH action and IESS pathophysiology.

Convergence of endothelial dysfunction, inflammation and glucocorticoid resistance in depression-related cardiovascular diseases

Major Depressive Disorder, or depression, has been extensively linked to dysregulated HPA axis function, chronic inflammation and cardiovascular diseases. While the former two have been studied in depth, the mechanistic connection between depression and cardiovascular disease is unclear. As major mediators of vascular homeostasis, vascular pathology and immune activity, endothelial cells represent an important player connecting the diseases. Exaggerated inflammation and glucocorticoid function are important topics to explore in the endothelial response to MDD. Glucocorticoid resistance in several cell types strongly promotes inflammatory signaling and results in worsened severity in many diseases. However, endothelial health and inflammation in chronic stress and depression are rarely considered from the perspective of glucocorticoid signaling and resistance. In this review, we aim to discuss (1) endothelial dysfunction in depression, (2) inflammation in depression, (3) general glucocorticoid resistance in depression and (4) endothelial glucocorticoid resistance in depression co-morbid inflammatory diseases. We will first describe vascular pathology, inflammation and glucocorticoid resistance separately in depression and then describe their potential interactions with one another in depression-relevant diseases. Lastly, we will hypothesize potential mechanisms by which glucocorticoid resistance in endothelial cells may contribute to vascular disease states in depressed people. Overall, endothelial-glucocorticoid signaling may play an important role in connecting depression and vascular pathology and warrants further study.

T cell infiltration mediates neurodegeneration and cognitive decline in Alzheimer's disease

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder with pathological features of β-amyloid (Aβ) and hyperphosphorylated tau protein accumulation in the brain, often accompanied by cognitive decline. So far, our understanding of the extent and role of adaptive immune responses in AD has been quite limited. T cells, as essential members of the adaptive immune system, exhibit quantitative and functional abnormalities in the brains of AD patients. Dysfunction of the blood-brain barrier (BBB) in AD is considered one of the factors leading to T cell infiltration. Moreover, the degree of neuronal loss in AD is correlated with the quantity of T cells. We first describe the differentiation and subset functions of peripheral T cells in AD patients and provide an overview of the key findings related to BBB dysfunction and how T cells infiltrate the brain parenchyma through the BBB. Furthermore, we emphasize the risk factors associated with AD, including Aβ, Tau protein, microglial cells, apolipoprotein E (ApoE), and neuroinflammation. We discuss their regulation of T cell activation and proliferation, as well as the connection between T cells, neurodegeneration, and cognitive decline. Understanding the innate immune response is crucial for providing comprehensive personalized therapeutic strategies for AD.

Elevated Interleukin-31 Levels in Serum, but Not CSF of Dogs with Steroid-Responsive Meningitis-Arteritis Suggest an Involvement in Its Pathogenesis

Steroid-responsive meningitis-arteritis (SRMA) is a predominantly Th-2 immune-mediated disease, but the exact pathomechanism remains unclear. Interleukin-31 (IL-31) is predominantly produced by T cells with a Th-2 phenotype during proinflammatory conditions. We hypothesize that IL-31 might be involved in the pathogenesis of SRMA. IL-31 was measured in archived samples (49 serum and 52 CSF samples) of dogs with SRMA, meningoencephalitis of unknown origin (MUO), infectious meningoencephalitis, and atopic dermatitis, and of healthy control dogs using a competitive canine IL-31 ELISA. The mean serum IL-31 level in dogs with SRMA (n = 18) was mildly higher compared to dogs with atopic dermatitis (n = 3, p = 0.8135) and MUO (n = 15, p = 0.7618) and markedly higher than in healthy controls (n = 10, p = 0.1327) and dogs with infectious meningoencephalitis (n = 3, no statistics). Dogs with SRMA in the acute stage of the disease and without any pre-treatment had the highest IL-31 levels. The mean CSF IL-31 value for dogs with SRMA (n = 23) was quite similar to that for healthy controls (n = 8, p = 0.4454) and did not differ markedly from dogs with MUO (n = 19, p = 0.8724) and infectious meningoencephalitis. Based on this study, an involvement of IL-31 in the pathogenesis of the systemic Th-2 immune-mediated immune response in SRMA can be assumed as a further component leading to an aberrant immune reaction.

Glucocorticoid Treatment in Acute Respiratory Distress Syndrome: An Overview on Mechanistic Insights and Clinical Benefit

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS), triggered by various pathogenic factors inside and outside the lungs, leads to diffuse lung injury and can result in respiratory failure and death, which are typical clinical critical emergencies. Severe acute pancreatitis (SAP), which has a poor clinical prognosis, is one of the most common diseases that induces ARDS. When SAP causes the body to produce a storm of inflammatory factors and even causes sepsis, clinicians will face a two-way choice between anti-inflammatory and anti-infection objectives while considering the damaged intestinal barrier and respiratory failure, which undoubtedly increases the difficulty of the diagnosis and treatment of SAP-ALI/ARDS. For a long time, many studies have been devoted to applying glucocorticoids (GCs) to control the inflammatory response and prevent and treat sepsis and ALI/ARDS. However, the specific mechanism is not precise, the clinical efficacy is uneven, and the corresponding side effects are endless. This review discusses the mechanism of action, current clinical application status, effectiveness assessment, and side effects of GCs in the treatment of ALI/ARDS (especially the subtype caused by SAP).

Blood Biomarkers in Takotsubo Syndrome Point to an Emerging Role for Inflammaging in Endothelial Pathophysiology

Takotsubo syndrome (TTS), an acute cardiac condition characterized by transient wall motion abnormalities mostly of the left ventricle, results in difficulties in diagnosing patients. We set out to present a detailed blood analysis of TTS patients analyzing novel markers to understand the development of TTS. Significant differences in proinflammatory cytokine expression patterns and sex steroid and glucocorticoid receptor (GR) expression levels were observed in the TTS patient collected. Remarkably, the measured catecholamine serum concentrations determined from TTS patient blood could be shown to be two orders of magnitude lower than the levels determined from experimentally induced TTS in laboratory animals. Consequently, the exposure of endothelial cells and cardiomyocytes in vitro to such catecholamine concentrations did not damage the cellular integrity or function of either endothelial cells forming the blood-brain barrier, endothelial cells derived from myocardium, or cardiomyocytes in vitro. Computational analysis was able to link the identified blood markers, specifically, the proinflammatory cytokines and glucocorticoid receptor GR to microRNA (miR) relevant in the ontogeny of TTS (miR-15) and inflammation (miR-21, miR-146a), respectively. Amongst the well-described risk factors of TTS (older age, female sex), inflammaging-related pathways were identified to add to these relevant risk factors or prediagnostic markers of TTS.

Glucocorticoids Orchestrate Adult Hippocampal Plasticity: Growth Points and Translational Aspects

The review analyzes modern concepts about the control of various mechanisms of the hippocampal neuroplasticity in adult mammals and humans by glucocorticoids. Glucocorticoid hormones ensure the coordinated functioning of key components and mechanisms of hippocampal plasticity: neurogenesis, glutamatergic neurotransmission, microglia and astrocytes, systems of neurotrophic factors, neuroinflammation, proteases, metabolic hormones, neurosteroids. Regulatory mechanisms are diverse; along with the direct action of glucocorticoids through their receptors, there are conciliated glucocorticoid-dependent effects, as well as numerous interactions between various systems and components. Despite the fact that many connections in this complex regulatory scheme have not yet been established, the study of the factors and mechanisms considered in the work forms growth points in the field of glucocorticoid-regulated processes in the brain and primarily in the hippocampus. These studies are fundamentally important for the translation into the clinic and the potential treatment/prevention of common diseases of the emotional and cognitive spheres and respective comorbid conditions.

Metalloproteinases and Tissue Inhibitors in Generalized Myasthenia Gravis. A Preliminary Study

INTRODUCTION

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have recently been proposed as promising biomarkers in different immune-mediated disorders. We evaluated the plasma levels of MMP-9 and MMP-2 and their tissue inhibitors TIMP-1 and TIMP-2 in a patients' cohort with generalized myasthenia gravis (MG).

METHODS

Plasma concentrations of MMP-9, MMP-2, TIMP-1 and TIMP-2 were evaluated in 14 patients with generalized MG and 13 age- and sex-matched healthy controls. The severity of disease was assessed by the modified Osserman classification.

RESULTS

Compared to the healthy subjects, MG patients had increased plasma concentrations of MMP-9, but reduced plasma levels of MMP-2 and TIMP-1. MG patients also showed a positive correlation between MMP-2 concentrations and disease severity. An increase in MMP-9 levels and MMP-9/TIMP-1 ratio and a decrease in MMP-2 levels and MMP-2/TIMP-2 ratio were detected in patients with generalized MG. Higher levels of MMP-2 correlated with greater disease severity.

DISCUSSION

Our preliminary findings suggest that MMPs and TIMPs could play a role in the pathogenesis of MG and might be associated with the risk of clinical deterioration.

Hemorrhagic Cerebral Insults and Secondary Takotsubo Syndrome: Findings in a Novel In Vitro Model Using Human Blood Samples

Intracranial hemorrhage results in devastating forms of cerebral damage. Frequently, these results also present with cardiac dysfunction ranging from ECG changes to Takotsubo syndrome (TTS). This suggests that intracranial bleeding due to subarachnoid hemorrhage (SAH) disrupts the neuro-cardiac axis leading to neurogenic stress cardiomyopathy (NSC) of different degrees. Following this notion, SAH and secondary TTS could be directly linked, thus contributing to poor outcomes. We set out to test if blood circulation is the driver of the brain-heart axis by investigating serum samples of TTS patients. We present a novel in vitro model combining SAH and secondary TTS to mimic the effects of blood or serum, respectively, on blood-brain barrier (BBB) integrity using in vitro monolayers of an established murine model. We consistently demonstrated decreased monolayer integrity and confirmed reduced Claudin-5 and Occludin levels by RT-qPCR and Western blot and morphological reorganization of actin filaments in endothelial cells. Both tight junction proteins show a time-dependent reduction. Our findings highlight a faster and more prominent disintegration of BBB in the presence of TTS and support the importance of the bloodstream as a causal link between intracerebral bleeding and cardiac dysfunction. This may represent potential targets for future therapeutic inventions in SAH and TTS.

Discerning the Role of Blood Brain Barrier Dysfunction in Alzheimer’s Disease

Alzheimer’s disease (AD) is the most common form of neurodegenerative disease. The predominant characteristics of AD are the accumulation of amyloid-β (Aβ) and hyperphosphorylated tau in the brain. Blood brain barrier (BBB) dysfunction as one of the causative factors of cognitive impairment is increasingly recognized in the last decades. However, the role of BBB dysfunction in AD pathogenesis is still not fully understood. It remains elusive whether BBB dysfunction is a consequence or causative fact of Aβ pathology, tau pathology, neuroinflammation, or other conditions. In this review, we summarized the major findings of BBB dysfunction in AD and the reciprocal relationships between BBB dysfunction, Aβ pathology, tau pathology, and neuroinflammation. In addition, the implications of BBB dysfunction in AD for delivering therapeutic drugs were presented. Finally, we discussed how to better determine the underlying mechanisms between BBB dysfunction and AD, as well as how to explore new therapies for BBB regulation to treat AD in the future.

Blood-Brain Barrier Dysfunction in the Pathogenesis of Major Depressive Disorder

Major depression represents a complex and prevalent psychological disease that is characterized by persistent depressed mood, impaired cognitive function and complicated pathophysiological and neuroendocrine alterations. Despite the multifactorial etiology of depression, one of the most recent factors to be identified as playing a critical role in the development of depression is blood-brain barrier (BBB) disruption. The occurrence of BBB integrity disruption contributes to the disturbance of brain homeostasis and leads to complications of neurological diseases, such as stroke, chronic neurodegenerative disorders, neuroinflammatory disorders. Recently, BBB associated tight junction disruption has been shown to implicate in the pathophysiology of depression and contribute to increased susceptibility to depression. However, the underlying mechanisms and importance of BBB damage in depression remains largely unknown. This review highlights how BBB disruption regulates the depression process and the possible molecular mechanisms involved in development of depression-induced BBB dysfunction. Moreover, insight on promising therapeutic targets for treatment of depression with associated BBB dysfunctions are also discussed.

Tailoring glucocorticoids in patients with severe COVID-19: a narrative review

OBJECTIVE

To discuss the pathogenesis of severe coronavirus disease 2019 (COVID-19) infection and the pharmacological effects of glucocorticoids (GCs) toward this infection. To review randomized controlled trials (RCTs) using GCs to treat patients with severe COVID-19, and investigate whether GC timing, dosage, or duration affect clinical outcomes. Finally. to discuss the use of biological markers, respiratory parameters, and radiological evidence to select patients for improved GC therapeutic precision.

BACKGROUND

COVID-19 has become an unprecedented global challenge. As GCs have been used as key immunomodulators to treat inflammation-related diseases, they may play key roles in limiting disease progression by modulating immune responses, cytokine production, and endothelial function in patients with severe COVID-19, who often experience excessive cytokine production and endothelial and renin-angiotensin system (RAS) dysfunction. Current clinical trials have partially proven this efficacy, but GC timing, dosage, and duration vary greatly, with no unifying consensus, thereby creating confusion.

METHODS

Publications through March 2021 were retrieved from the Web of Science and PubMed. Results from cited references in published articles were also included.

CONCLUSIONS

GCs play key roles in treating severe COVID-19 infections. Pharmacologically, GCs could modulate immune cells, reduce cytokine and chemokine, and improve endothelial functions in patients with severe COVID-19. Benefits of GCs have been observed in multiple clinical trials, but the timing, dosage and duration vary across studies. Tapering as an option is not widely accepted. However, early initiation of treatment, a tailored dosage with appropriate tapering may be of particular importance, but evidence is inconclusive and more investigations are needed. Biological markers, respiratory parameters, and radiological evidence could also help select patients for specific tailored treatments.

Modulated Start-Up Mode of Cancer Cell Migration Through Spinophilin-Tubular Networks

Spinophilin (SPL) is a multifunctional actin-binding scaffolding protein. Although increased research on SPL in cancer biology has revealed a tumor suppressive role, its modulation in cancer biology, and oncological relevance remains elusive. Thus, we determined the role of SPL in the modulation of the junctional network and cellular migration in A549 lung cancer cell line. Knockdown of SPL promoted cancer cell invasion in agarose spot and scratch wound assays. Attenuation of SPL expression also enhanced invadopodia, as revealed by enhanced vinculin spots, and enhanced sodium bicarbonate cotransporter NBC activity without enhancing membranous expression of NBCn1. Disruption of the tubular structure with nocodazole treatment revealed enhanced SPL expression and reduced NBC activity and A549 migration. SPL-mediated junctional modulation and tubular stability affected bicarbonate transporter activity in A549 cells. The junctional modulatory function of SPL in start-up migration, such as remodeling of tight junctions, enhanced invadopodia, and increased NBC activity, revealed here would support fundamental research and the development of an initial target against lung cancer cell migration.

Modulating the Barrier Function of Human Alveolar Epithelial (hAELVi) Cell Monolayers as a Model of Inflammation

The incidence of inflammatory lung diseases such as acute respiratory distress syndrome (ARDS) remains an important problem, particularly in the present time with the Covid-19 pandemic. However, an adequate in vitro test system to monitor the barrier function of the alveolar epithelium during inflammation and for assessing anti-inflammatory drugs is urgently needed. Therefore, we treated human Alveolar Epithelial Lentivirus-immortalised cells (hAELVi cells) with the pro-inflammatory cytokines TNF-α (25 ng/ml) and IFN-γ (30 ng/ml), in the presence or absence of hydrocortisone (HC). While TNF-α and IFN-γ are known to reduce epithelial barrier properties, HC could be expected to protect the barrier function and result in an anti-inflammatory effect. We investigated the impact of anti-inflammatory/inflammatory treatment on transepithelial electrical resistance (TEER) and the apparent permeability coefficient (P app) of the low permeability marker sodium fluorescein (NaFlu). After incubating hAELVi cells for 48 hours with a combination of TNF-α and IFN-γ, there was a significant decrease in TEER and a significant increase in the P app. The presence of HC maintained the TEER values and barrier properties, so that no significant P app change was observed. By using hAELVi cells to study anti-inflammatory drugs in vitro, the need for animal experiments could be reduced and pulmonary drug development accelerated.

Changes in Gene and Protein Expression of Metalloproteinase-2 and -9 and Their Inhibitors TIMP2 and TIMP3 in Different Parts of Fluoride-Exposed Rat Brain

Fluoride (F) exposure decreases brain receptor activity and neurotransmitter production. A recent study has shown that chronic fluoride exposure during childhood can affect cognitive function and decrease intelligence quotient, but the mechanism of this phenomenon is still incomplete. Extracellular matrix (ECM) and its enzymes are one of the key players of neuroplasticity which is essential for cognitive function development. Changes in the structure and the functioning of synapses are caused, among others, by ECM enzymes. These enzymes, especially matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), are involved in both physiological processes, such as learning or memory, and pathological processes like glia scare formation, brain tissue regeneration, brain-blood barrier damage and inflammation. Therefore, in this study, we examined the changes in gene and protein expression of MMP2, MMP9, TIMP2 and TIMP3 in the prefrontal cortex, hippocampus, striatum and cerebellum of rats (Wistar) exposed to relatively low F doses (50 mg/L in drinking water) during the pre- and neonatal period. We found that exposure to F during pre- and postnatal period causes a change in the mRNA and protein level of MMP2, MMP9, TIMP2 and TIMP3 in the prefrontal cortex, striatum, hippocampus and cerebellum. These changes may be associated with many disorders that are observed during F intoxication. MMPs/TIMPs imbalance may contribute to cognitive impairments. Moreover, our results suggest that a chronic inflammatory process and blood-brain barrier (BBB) damage occur in rats’ brains exposed to F.

The role of EP2 receptors in mediating the ultra-long-lasting intraocular pressure reduction by JV-GL1

BACKGROUND

A single application of JV-GL1 substantially lowers non-human primate intraocular pressure (IOP) for about a week, independent of dose. This highly protracted effect does not correlate with its ocular biodisposition or correlate with the once-daily dosing regimen for other prostanoid EP₂ receptor agonists such as trapenepag or omidenepag. The underlying pharmacological mechanism for the multiday extended activity of JV-GL1 is highly intriguing. The present studies were intended to determine EP₂ receptor involvement in mediating the long-term ocular hypotensive activity of JV-GL1 by using mice genetically deficient in EP₂ receptors.

METHODS

The protracted IOP reduction produced by JV-GL1 was investigated in C57BL/6J and EP₂ receptor knock-out mice (B6.129-Ptger2^tm1Brey /J; EP₂KO). Both ocular normotensive and steroid-induced ocular hypertensive (SI-OHT) mice were studied. IOP was measured tonometrically under general anaesthesia. Aqueous humour outflow facility was measured ex vivo using iPerfusion in normotensive C57BL/6J mouse eyes perfused with 100 nM de-esterified JV-GL1 and in SI-OHT C57BL/6J mouse eyes that had received topical JV-GL1 (0.01%) 3 days prior.

RESULTS

Both the initial 1-day and the protracted multiday effects of JV-GL1 in the SI-OHT model for glaucoma were abolished by deletion of the gene encoding the EP₂ receptor. Thus, JV-GL1 did not lower IOP in SI-OHT EP₂KO mice, but in littermate SI-OHT EP₂WT control mice, JV-GL1 statistically significantly lowered IOP for 4-6 days.

CONCLUSIONS

Both the 1-day and the long-term effects of JV-GL1 on IOP are entirely EP₂ receptor dependent.

Neuroprotective Effects of Isosteviol Sodium in Murine Brain Capillary Cerebellar Endothelial Cells (cerebEND) After Hypoxia

Ischemic stroke is one of the leading causes of death worldwide. It damages neurons and other supporting cellular elements in the brain. However, the impairment is not only confined to the region of assault but the surrounding area as well. Besides, it also brings about damage to the blood-brain barrier (BBB) which in turn leads to microvascular failure and edema. Hence, this necessitates an on-going, continuous search for intervention strategies and effective treatment. Of late, the natural sweetener stevioside proved to exhibit neuroprotective effects and therapeutic benefits against cerebral ischemia-induced injury. Its injectable formulation, isosteviol sodium (STVNA) also demonstrated favorable results. Nonetheless, its effects on the BBB have not yet been investigated to date. As such, this present study was designed to assess the effects of STVNA in our in vitro stroke model of the BBB.The integrity and permeability of the BBB are governed and maintained by tight junction proteins (TJPs) such as claudin-5 and occludin. Our data show increased claudin-5 and occludin expression in oxygen and glucose (OGD)-deprived murine brain capillary cerebellar endothelial cells (cerebEND) after STVNa treatment. Likewise, the upregulation of the transmembrane protein integrin-αv was also observed. Finally, cell volume was reduced with the simultaneous administration of STVNA and OGD in cerebEND cells. In neuropathologies such as stroke, the failure of cell volume control is a major feature leading to loss of cells in the penumbra as well as adverse outcomes. Our initial findings, therefore, point to the neuroprotective effects of STVNA at the BBB in vitro, which warrant further investigation for a possible future clinical intervention.

Increased Catecholamine Levels and Inflammatory Mediators Alter Barrier Properties of Brain Microvascular Endothelial Cells in vitro

Recent studies have suggested a pathogenetic link between ischemic stroke and Takotsubo cardiomyopathy (TCM) with poor outcome, when occurring simultaneously. Increased catecholamine (CAT) levels as well as elevated inflammatory mediators (INF) are found in the blood of patients with ischemic stroke concomitant with Takotsubo syndrome (TTS). On molecular level, the impact of these stressors combined with hypoxemia could compromise the integrity of the blood brain barrier (BBB) resulting in poor outcomes. As a first step in the direction of investigating possible molecular mechanisms, an in vitro model of the described pathological constellation was designed. An immortalized murine microvascular endothelial cell line from the cerebral cortex (cEND) was used as an established in vitro model of the BBB. cEND cells were treated with supraphysiological concentrations of CAT (dopamine, norepinephrine, epinephrine) and INF (TNF-α and Interleukin-6). Simultaneously, cells were exposed to oxygen glucose deprivation (OGD) as an established in vitro model of ischemic stroke with/without subsequent reoxygenation. We investigated the impact on cell morphology and cell number by immunofluorescence staining. Furthermore, alterations of selected tight and adherens junction proteins forming paracellular barrier as well as integrins mediating cell-matrix adhesion were determined by RT-PCR and/or Western Blot technique. Especially by choosing this wide range of targets, we give a detailed overview of molecular changes leading to compromised barrier properties. Our data show that the proteins forming the BBB and the cell count are clearly influenced by CAT and INF applied under OGD conditions. Most of the investigated proteins are downregulated, so a negative impact on barrier integrity can be assumed. The structures affected by treatment with CAT and INF are potential targets for future therapies in ischemic stroke and TTS.

Simvastatin, edaravone and dexamethasone protect against kainate-induced brain endothelial cell damage

BACKGROUND

Excitotoxicity is a central pathological pathway in many neurological diseases with blood-brain barrier (BBB) dysfunction. Kainate, an exogenous excitotoxin, induces epilepsy and BBB damage in animal models, but the direct effect of kainate on brain endothelial cells has not been studied in detail. Our aim was to examine the direct effects of kainate on cultured cells of the BBB and to test three anti-inflammatory and antioxidant drugs used in clinical practice, simvastatin, edaravone and dexamethasone, to protect against kainate-induced changes.

METHODS

Primary rat brain endothelial cell, pericyte and astroglia cultures were used to study cell viability by impedance measurement. BBB permeability was measured on a model made from the co-culture of the three cell types. The production of nitrogen monoxide and reactive oxygen species was followed by fluorescent probes. The mRNA expression of kainate receptors and nitric oxide synthases were studied by PCR.

RESULTS

Kainate damaged brain endothelial cells and made the immunostaining of junctional proteins claudin-5 and zonula occludens-1 discontinuous at the cell border indicating the opening of the barrier. The permeability of the BBB model for marker molecules fluorescein and albumin and the production of nitric oxide in brain endothelial cells were increased by kainate. Simvastatin, edaravone and dexamethasone protected against the reduced cell viability, increased permeability and the morphological changes in cellular junctions caused by kainate. Dexamethasone attenuated the elevated nitric oxide production and decreased the inducible nitric oxide synthase (NOS2/iNOS) mRNA expression increased by kainate treatment.

CONCLUSION

Kainate directly damaged cultured brain endothelial cells. Simvastatin, edaravone and dexamethasone protected the BBB model against kainate-induced changes. Our results confirmed the potential clinical usefulness of these drugs to attenuate BBB damage.

Tight junction proteins in gastrointestinal and liver disease

Over the past two decades a growing body of evidence has demonstrated an important role of tight junction (TJ) proteins in the physiology and disease biology of GI and liver disease. On one side, TJ proteins exert their functional role as integral proteins of TJs in forming barriers in the gut and the liver. Furthermore, TJ proteins can also be expressed outside TJs where they play important functional roles in signalling, trafficking and regulation of gene expression. A hallmark of TJ proteins in disease biology is their functional role in epithelial-to-mesenchymal transition. A causative role of TJ proteins has been established in the pathogenesis of colorectal cancer and gastric cancer. Among the best characterised roles of TJ proteins in liver disease biology is their function as cell entry receptors for HCV-one of the most common causes of hepatocellular carcinoma. At the same time TJ proteins are emerging as targets for novel therapeutic approaches for GI and liver disease. Here we review our current knowledge of the role of TJ proteins in the pathogenesis of GI and liver disease biology and discuss their potential as therapeutic targets.

Cerebrovascular manifestations of herpes simplex virus infection of the central nervous system: a systematic review

BACKGROUND

Intracerebral hemorrhage and ischemic stroke are increasingly recognized complications of central nervous system (CNS) infection by herpes simplex virus (HSV).

AIM OF THE STUDY

To analyze clinical, imaging, and laboratory findings and outcomes of cerebrovascular manifestations of HSV infection.

METHODS

Systematic literature review from January 2000 to July 2018.

RESULTS

We identified 38 patients (median age 45 years, range 1-73) comprising 27 cases of intracerebral hemorrhage, 10 of ischemic stroke, and 1 with cerebral venous sinus thrombosis. Intracerebral hemorrhage was predominantly (89%) a complication of HSV encephalitis located in the temporal lobe. Hematoma was present on the first brain imaging in 32%, and hematoma evacuation was performed in 30% of these cases. Infarction was frequently multifocal, and at times preceded by hemorrhage (20%). Both a stroke-like presentation and presence of HSV encephalitis in a typical location were rare (25% and 10%, respectively). There was evidence of cerebral vasculitis in 63%, which was exclusively located in large-sized vessels. Overall mortality was 21% for hemorrhage and 0% for infarction. HSV-1 was a major cause of hemorrhagic complications, whereas HSV-2 was the most prevalent agent in the ischemic manifestations.

CONCLUSION

We found a distinct pathogenesis, cause, and outcome for HSV-related cerebral hemorrhage and infarction. Vessel disruption within a temporal lobe lesion caused by HSV-1 is the presumed mechanism for hemorrhage, which may potentially have a fatal outcome. Brain ischemia is mostly related to multifocal cerebral large vessel vasculitis associated with HSV-2, where the outcome is more favorable.

Hemostatic nanoparticles increase survival, mitigate neuropathology and alleviate anxiety in a rodent blast trauma model

Explosions account for 79% of combat related injuries and often lead to polytrauma, a majority of which include blast-induced traumatic brain injuries (bTBI). These injuries lead to internal bleeding in multiple organs and, in the case of bTBI, long term neurological deficits. Currently, there are no treatments for internal bleeding beyond fluid resuscitation and surgery. There is also a dearth of treatments for TBI. We have developed a novel approach using hemostatic nanoparticles that encapsulate an anti-inflammatory, dexamethasone, to stop the bleeding and reduce inflammation after injury. We hypothesize that this will improve not only survival but long term functional outcomes after blast polytrauma. Poly(lactic-co-glycolic acid) hemostatic nanoparticles encapsulating dexamethasone (hDNPs) were fabricated and tested following injury along with appropriate controls. Rats were exposed to a single blast wave using an Advanced Blast Simulator, inducing primary blast lung and bTBI. Survival was elevated in the hDNPs group compared to controls. Elevated anxiety parameters were found in the controls, compared to hDNPs. Histological analysis indicated that apoptosis and blood-brain barrier disruption in the amygdala were significantly increased in the controls compared to the hDNPs and sham groups. Immediate intervention is crucial to mitigate injury mechanisms that contribute to emotional deficits.

Dexamethasone inhibits activation of monocytes/macrophages in a milieu rich in 27-oxygenated cholesterol

Molecular mechanisms underlying the decreased number of macrophages and T cells in the arteries of cholesterol-fed-rabbits following dexamethasone administration are unknown. We investigated the possibility that dexamethasone could affect activation of monocytic cells induced by oxygenated derivatives of cholesterol (oxysterols) using THP-1 monocyte/macrophage cells. 27-Hydroxycholesterol (27OHChol), an oxysterol elevated with hypercholesterolemia, enhanced production of CCL2, known as MCP1, chemokine from monocytes/macrophages and migration of the monocytic cells, but the CCL2 production and the cell migration were reduced by treatment with dexamethasone. Dexamethasone inhibited superproduction of CCL2 induced by 27OHChol plus LPS and attenuated transcription of matrix metalloproteinase 9 as well as secretion of its active gene product induced by 27OHChol. The drug downregulated cellular and surface levels of CD14 and blocked release of soluble CD14 without altering transcription of the gene. Dexamethasone also inhibited expression and phosphorylation of the NF-κB p65 subunit enhanced by 27OHChol. Collectively, these results indicate that dexamethasone inhibits activation of monocytes/macrophages in response to 27OHChol, thereby leading to decreased migration of inflammatory cells in milieu rich in oxygenated derivatives of cholesterol.

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.

The Balance of Tissue Inhibitor of Metalloproteinase-1 and Matrix Metalloproteinase-9 in the Autoimmune Inner Ear Disease Patients

Tissue inhibitor of metalloproteinase-1 (TIMP-1) is a protein implicated in the control of inflammation in a number of autoimmune diseases. We hypothesized that the balance of TIMP-1 and matrix metalloproteinase-9 (MMP-9) may influence the control or perpetuation of inflammation in corticosteroid-responsive (RES) and corticosteroid-resistant (NR) autoimmune inner ear disease (AIED) patients. In the present study, we observed that plasma from AIED patients exhibited greater levels of TIMP-1 values compared with normal healthy controls. TIMP-1 abrogates lipopolysaccharide-mediated interleukin (IL)-1β release from peripheral blood mononuclear cells in a dose-dependent manner. RES AIED patients have higher basal TIMP-1 levels and produce more TIMP-1 in response to IL-1β. Conversely, consistent with our previous studies, we found that NR patients have higher basal MMP-9 levels and produce more MMP-9 levels in response to IL-1β.

Theophylline action on primary human bronchial epithelial cells under proinflammatory stimuli and steroidal drugs: a therapeutic rationale approach

Theophylline is a natural compound present in tea. Because of its property to relax smooth muscle it is used in pharmacology for the treatment of airway diseases (ie, chronic obstructive pulmonary disease, asthma). However, this effect on smooth muscle is dose dependent and it is related to the development of side effects. Recently, an increasing body of evidence suggests that theophylline, at low concentrations, also has anti-inflammatory effects related to the activation of histone deacetylases. In this study, we evaluated the effects of theophylline alone and in combination with corticosteroids on human bronchial epithelial cells under inflammatory stimuli. Theophylline administrated alone was not able to reduce growth-stimulating signaling via extracellular signal-regulated kinases activation and matrix metalloproteases release, whereas it strongly counteracts this biochemical behavior when administered in the presence of corticosteroids. These data provide scientific evidence for supporting the rationale for the pharmacological use of theophylline and corticosteroid combined drug.

Endothelial Response to Glucocorticoids in Inflammatory Diseases

The endothelium plays a crucial role in inflammation. A balanced control of inflammation requires the action of glucocorticoids (GCs), steroidal hormones with potent cell-specific anti-inflammatory properties. Besides the classic anti-inflammatory effects of GCs on leukocytes, recent studies confirm that endothelial cells also represent an important target for GCs. GCs regulate different aspects of endothelial physiology including expression of adhesion molecules, production of pro-inflammatory cytokines and chemokines, and maintenance of endothelial barrier integrity. However, the regulation of endothelial GC sensitivity remains incompletely understood. In this review, we specifically examine the endothelial response to GCs in various inflammatory diseases ranging from multiple sclerosis, stroke, sepsis, and vasculitis to atherosclerosis. Shedding more light on the cross talk between GCs and endothelium will help to improve existing therapeutic strategies and develop new therapies better tailored to the needs of patients.

Glucocorticoids in the management of peritumoral brain edema: a review of molecular mechanisms

Peritumoral brain edema (PTBE) is mediated by blood-brain barrier breakdown. PTBE results from interstitial vasogenic brain edema due to vascular endothelial growth factor and other inflammatory products of brain tumors. Glucocorticoids (GCs) are the mainstay for treatment of PTBE despite significant systemic side effects. GCs are thought to affect multiple cell types in the edematous brain. Here, we review preclinical studies of GC effects on edematous brain and review mechanisms underlying GC action on tumor cells, endothelial cells, and astrocytes. GCs may reduce tumor cell viability and suppress vascular endothelial growth factor (VEGF) production in tumor cells. Modulation of expression and distribution of tight junction proteins occludin, claudin-5, and ZO-1 in endothelial cells likely plays a central role in GC action on endothelial cells. GCs may also have an effect on astrocyte angiopoietin production and limited effect on astrocyte aquaporin. A better understanding of these molecular mechanisms may lead to the development of novel therapeutics for management of PTBE with a better side effect profile.

Prazosin Can Prevent Glucocorticoid Mediated Capillary Rarefaction

Glucocorticoids (GC) elicit skeletal muscle capillary rarefaction, which can subsequently impair blood distribution and muscle function; however, the mechanisms have not been established. We hypothesized that CORT would inhibit endothelial cell survival signals but that treatment with the alpha-1 adrenergic receptor inhibitor prazosin, which leads to angiogenesis in skeletal muscle of healthy rats, would reverse these effects and induce angiogenesis within the skeletal muscle of corticosterone (CORT)-treated rats. Male Sprague Dawley rats were implanted subcutaneously with CORT pellets (400 mg/rat), with or without concurrent prazosin treatment (50mg/L in drinking water), for 1 or 2 weeks. Skeletal muscle capillary rarefaction, as indicated by a significant reduction in capillary-to-fiber ratio (C:F), occurred after 2 weeks of CORT treatment. Concurrent prazosin administration prevented this capillary rarefaction in CORT-treated animals but did not induce angiogenesis or arteriogenesis as was observed with prazosin treatment in control rats. CORT treatment reduced the mRNA level of Angiopoietin-1 (Ang-1), which was partially offset in the muscles of rats that received 2 weeks of co-treatment with prazosin. In 2W CORT animals, prazosin treatment elicited a significant increase in vascular endothelial growth factor-A (VEGF-A) mRNA and protein. Conversely prazosin did not rescue CORT-induced reductions in transforming growth factor beta-1 (TGFβ1 and matrix metalloproteinase-2 (MMP-2) mRNA. To determine if CORT impaired shear stress dependent signaling, cultured rat skeletal muscle endothelial cells were pre-treated with CORT (600nM) for 48 hours, then exposed to 15 dynes/cm² shear stress or maintained with no flow. CORT blunted the shear stress-induced increase in pSer473 Akt, while pThr308 Akt, ERK1/2 and p38 phosphorylation and nitric oxide (NO) production were unaffected. This study demonstrates that GC-mediated capillary rarefaction is associated with a reduction in Ang-1 mRNA within the skeletal muscle microenvironment and that concurrent prazosin treatment effectively increases VEGF-A levels and prevents capillary loss.

Tight Junctions and the Tumor Microenvironment

PURPOSE OF REVIEW

Tight junctions (TJs) are specialized differentiations of epithelial and endothelial cell membranes. TJs play an important role in the adhesion of cells and their interaction with each other. Most cancers originate from epithelial cells. Thus, it is of significance to examine the role of TJs in the tumor microenvironment (TME) and how they affect cancer metastasis.

RECENT FINDINGS

In epithelium-derived cancers, intactness of the primary tumor mass is influenced by intercellular structures as well as cell-to-cell adhesion. Irregularities of these factors may lead to tumor dissociation and subsequent metastasis. Low expression of TJs is observed among highly metastatic cancer cells.

SUMMARY

In this review, we summarized findings from current literature in consideration of the role of TJs in relation to the TME and cancer. Deeper understanding of the mechanisms leading to TJ dysregulation is needed to facilitate the design and conceptualization of new and better therapeutic strategies for cancer.

In vitro models of the blood-brain barrier: An overview of commonly used brain endothelial cell culture models and guidelines for their use

The endothelial cells lining the brain capillaries separate the blood from the brain parenchyma. The endothelial monolayer of the brain capillaries serves both as a crucial interface for exchange of nutrients, gases, and metabolites between blood and brain, and as a barrier for neurotoxic components of plasma and xenobiotics. This "blood-brain barrier" function is a major hindrance for drug uptake into the brain parenchyma. Cell culture models, based on either primary cells or immortalized brain endothelial cell lines, have been developed, in order to facilitate in vitro studies of drug transport to the brain and studies of endothelial cell biology and pathophysiology. In this review, we aim to give an overview of established in vitro blood-brain barrier models with a focus on their validation regarding a set of well-established blood-brain barrier characteristics. As an ideal cell culture model of the blood-brain barrier is yet to be developed, we also aim to give an overview of the advantages and drawbacks of the different models described.

The blood-brain barrier

In autoimmune neurologic disorders, the blood-brain barrier (BBB) plays a central role in immunopathogenesis, since this vascular interface is an entry path for cells and effector molecules of the peripheral immune system to reach the target organ, the central nervous system (CNS). The BBB's unique anatomic structure and the tightly regulated interplay of its cellular and acellular components allow for maintenance of brain homeostasis, regulation of influx and efflux, and protection from harm; these ensure an optimal environment for the neuronal network to function properly. In both health and disease, the BBB acts as mediator between the periphery and the CNS. For example, immune cell trafficking through the cerebral vasculature is essential to clear microbes or cell debris from neural tissues, while poorly regulated cellular transmigration can underlie or worsen CNS pathology. In this chapter, we focus on the specialized multicellular structure and function of the BBB/neurovascular unit and discuss how BBB breakdown can precede or be a consequence of neuroinflammation. We introduce the blood-cerebrospinal fluid barrier and include a brief aside about evolutionary aspects of barrier formation and refinements. Lastly, since restoration of barrier function is considered key to ameliorate neurologic disease, we speculate about new therapeutic avenues to repair a damaged BBB.

How Hormones Influence Composition and Physiological Function of the Brain-Blood Barrier

Hormones exert many actions in the brain. Their access and effects in the brain are regulated by the blood-brain barrier (BBB). Hormones as other substances may enter the brain and vice versa either by paracellular way requiring breaching tight junctions stitching the endothelial cells composing the BBB, or by passage through the cells (transcellular way). Hormones influence both ways through their receptors, both membrane and intracellular, present on/in the BBB. In the review the main examples are outlined how hormones influence the expression and function of proteins forming the tight junctions, as well as how they regulate expression and function of major protein transporters mediating transport of various substances including hormone themselves.

The blood-brain barrier as a target in traumatic brain injury treatment

Traumatic brain injury (TBI) is one of the most frequent causes of death in the young population. Several clinical trials have unsuccessfully focused on direct neuroprotective therapies. Recently immunotherapeutic strategies shifted into focus of translational research in acute CNS diseases. Cross-talk between activated microglia and blood-brain barrier (BBB) could initiate opening of the BBB and subsequent recruitment of systemic immune cells and mediators into the brain. Stabilization of the BBB after TBI could be a promising strategy to limit neuronal inflammation, secondary brain damage and acute neurodegeneration. This review provides an overview on the pathophysiology of TBI and brain edema formation including definitions and classification of TBI, current clinical treatment strategies, as well as current understanding on the underlying cellular processes. A summary of in vivo and in vitro models to study different aspects of TBI is presented. Three mechanisms proposed for stabilization of the BBB, myosin light chain kinases, glucocorticoid receptors and peroxisome proliferator-activated receptors are reviewed for their influence on barrier-integrity and outcome after TBI. In conclusion, the BBB is recommended as a promising target for the treatment of traumatic brain injury, and it is suggested that a combination of BBB stabilization and neuroprotectants may improve therapeutic success.

Steroids and the blood-brain barrier: therapeutic implications

Steroids have a wide spectrum of impact, serving as fundamental regulators of nearly every physiological process within the human body. Therapeutic applications of steroids are equally broad, with a diverse range of medications and targets. Within the central nervous system (CNS), steroids influence development, memory, behavior, and disease outcomes. Moreover, steroids are well recognized as to their impact on the vascular endothelium. The blood-brain barrier (BBB) at the level of the brain microvascular endothelium serves as the principle interface between the peripheral circulation and the brain. Steroids have been identified to impact several critical properties of the BBB, including cellular efflux mechanisms, nutrient uptake, and tight junction integrity. Such actions not only influence brain homeostasis but also the delivery of CNS-targeted therapeutics. A greater understanding of the respective steroid-BBB interactions may shed further light on the differential treatment outcomes observed across CNS pathologies. In this chapter, we examine the current therapeutic implications of steroids respective to BBB structure and function, with emphasis on glucocorticoids and estrogens.

Inhibition of proteasome-mediated glucocorticoid receptor degradation restores nitric oxide bioavailability in myocardial endothelial cells in vitro

BACKGROUND INFORMATION

Glucocorticoids (GCs), including the synthetic GC derivate dexamethasone, are widely used as immunomodulators. One of the numerous side effects of dexamethasone therapy is hypertension arising from reduced release of the endothelium-derived vasodilator nitric oxide (NO).

RESULTS

Herein, we described the role of dexamethasone and its glucocorticoid receptor (GR) in the regulation of NO synthesis in vitro using the mouse myocardial microvascular endothelial cell line, MyEND. GC treatment caused a firm decrease of extracellular NO levels, whereas the expression of endothelial NO synthase (eNOS) was not affected. However, GC application induced an impairment of tetrahydrobiopterin (BH4 ) concentrations as well as GTP cyclohydrolase-1 (GTPCH-1) expression, both essential factors for NO production upstream of eNOS. Moreover, dexamethasone stimulation resulted in a substantially decreased GR gene and protein expression in MyEND cells. Importantly, inhibition of proteasome-mediated proteolysis of the GR or overexpression of an ubiquitination-defective GR construct improved the bioavailability of BH4 and strengthened GTPCH-1 expression and eNOS activity.

CONCLUSIONS

Summarising our results, we propose a new mechanism involved in the regulation of NO signalling by GCs in myocardial endothelial cells. We suggest that a sufficient GR protein expression plays a crucial role for the management of GC-induced harmful adverse effects, including deregulations of vasorelaxation arising from disturbed NO biosynthesis.

Maternal food restriction modulates cerebrovascular structure and contractility in adult rat offspring: effects of metyrapone

Although the effects of prenatal undernutrition on adult cardiovascular health have been well studied, its effects on the cerebrovascular structure and function remain unknown. We used a pair-fed rat model of 50% caloric restriction from day 11 of gestation to term, with ad libitum feeding after birth. We validated that maternal food restriction (MFR) stress is mediated by glucocorticoids by administering metyrapone, a corticosterone synthesis inhibitor, to MFR mothers at day 11 of gestation. At age 8 mo, offspring from Control, MFR, and MFR + Metyrapone groups were killed, and middle cerebral artery (MCA) segments were studied using vessel-bath myography and confocal microscopy. Colocalization of smooth muscle α-actin (SMαA) with nonmuscle (NM), SM1 and SM2 myosin heavy-chain (MHC) isoforms was used to assess smooth muscle phenotype. Our results indicate that artery stiffness and wall thickness were increased, pressure-evoked myogenic reactivity was depressed, and myofilament Ca(2+) sensitivity was decreased in offspring of MFR compared with Control rats. MCA from MFR offspring exhibited a significantly greater SMαA/NM colocalization, suggesting that the smooth muscle cells had been altered toward a noncontractile phenotype. MET significantly reversed the effects of MFR on stiffness but not myogenic reactivity, lowered SMαA/NM colocalization, and increased SMαA/SM2 colocalization. Together, our data suggest that MFR alters cerebrovascular contractility via both glucocorticoid-dependent and glucocorticoid-independent mechanisms.

Glucocorticoids and endothelial cell barrier function

Glucocorticoids (GCs) are steroid hormones that have inflammatory and immunosuppressive effects on a wide variety of cells. They are used as therapy for inflammatory disease and as a common agent against edema. The blood brain barrier (BBB), comprising microvascular endothelial cells, serves as a permeability screen between the blood and the brain. As such, it maintains homeostasis of the central nervous system (CNS). In many CNS disorders, BBB integrity is compromised. GC treatment has been demonstrated to improve the tightness of the BBB. The responses and effects of GCs are mediated by the ubiquitous GC receptor (GR). Ligand-bound GR recognizes and binds to the GC response element located within the promoter region of target genes. Transactivation of certain target genes leads to improved barrier properties of endothelial cells. In this review, we deal with the role of GCs in endothelial cell barrier function. First, we describe the mechanisms of GC action at the molecular level. Next, we discuss the regulation of the BBB by GCs, with emphasis on genes targeted by GCs such as occludin, claudins and VE-cadherin. Finally, we present currently available GC therapeutic strategies and their limitations.

Development, maintenance and disruption of the blood-brain barrier

The interface between the blood circulation and the neural tissue features unique characteristics that are encompassed by the term 'blood-brain barrier' (BBB). The main functions of this barrier, namely maintenance of brain homeostasis, regulation of influx and efflux transport, and protection from harm, are determined by its specialized multicellular structure. Every constituent cell type makes an indispensable contribution to the BBB's integrity. But if one member of the BBB fails, and as a result the barrier breaks down, there can be dramatic consequences and neuroinflammation and neurodegeneration can occur. In this Review, we highlight recently gained mechanistic insights into the development and maintenance of the BBB. We then discuss how BBB disruption can cause or contribute to neurological disease. Finally, we examine how this knowledge can be used to explore new possibilities for BBB repair.

Endothelial cell TIMP-1 is upregulated by shear stress via Sp-1 and the TGFβ1 signaling pathways

Laminar shear stress promotes vascular integrity by inhibiting proteolysis of the extracellular matrix (ECM) surrounding the microvasculature. We hypothesized that the matrix metalloproteinase inhibitor TIMP-1 would be upregulated in endothelial cells exposed to shear stress. Microvascular endothelial cells isolated from rat or mouse skeletal muscles were exposed to laminar shear stress for 2, 4, or 24 h. A biphasic increase in TIMP-1 protein was observed at 2 and 24 h of shear stress exposure. Sp-1 siRNA prevented the increase in TIMP-1 after 2, but not 24, hours of shear exposure. TGFβ production and Smad2/3 phosphorylation are increased by shear stress. Inhibition of TGFβ signaling, either by use of the TGFβ receptor 1 inhibitor SB-431542 or with Smad 2/3 siRNA, abrogated the shear stress-induced increase in TIMP-1 mRNA after 24 h of shear stress exposure. These results suggest that both acute and chronic elevated laminar shear stress act to maintain vessel integrity through increasing TIMP-1 production, but that the TGFβ signaling pathway is essential to maintain TIMP-1 expression during chronic shear stress.

Effect of dexamethasone administered with magnesium sulfate on inflammation-mediated degradation of the blood-brain barrier using an in vitro model

Patients at risk for preterm delivery are frequently administered both antenatal steroids for fetal maturation and magnesium sulfate for neuroprotection. In this study, we investigate whether steroids coadministered with magnesium sulfate preserve blood-brain barrier integrity in neuroinflammation. Human umbilical vein endothelial cells were grown in astroglial conditioned media in a 2-chamber cell culture apparatus. Treatment with tumor necrosis factor-α (TNF-α) or catalytically active recombinant matrix metalloproteinase 9 (MMP-9) simulated neuroinflammation. Membrane integrity was assessed by zona occludens 1 (ZO-1) immunoreactivity, permeability to fluorescently conjugated dextran, and transendothelial electrical resistance (TEER). The TNF-α and MMP-9 treatment increased the rate of dextran transit, decreased TEER, and decreased ZO-1 immunoreactivity at junctional interfaces. Dexamethasone pretreatment alone or in combination with 0.5 mmol/L magnesium sulfate preserved monolayer integrity after inflammatory insult. Magnesium sulfate alone was not protective. This study supports a possible interaction between steroids and magnesium in neuroprotection.

Matrix metalloproteinases and their tissue inhibitors in serum and cerebrospinal fluid of children with Japanese encephalitis virus infection

The expression of matrix metalloproteinases (MMPs) is tightly regulated at the level of gene transcription, conversion of pro-enzyme to active MMPs, and the action of tissue inhibitors of metalloproteinases (TIMPs). The present study aimed to investigate the expression of some specific MMPs (2, 7, 9) and TIMPs (1, 2, 3) in serum and cerebrospinal fluid (CSF) of children with Japanese encephalitis virus (JEV) infection. Serum and CSF levels of MMPs and TIMPs in children with JEV infection and disease control (DC) were compared. The CSF and serum concentrations of MMP-2, TIMP-2 and TIMP-3 were significantly higher in children with JEV infection compared to DC. The concentration of MMP-9 in serum was significantly higher in children with JEV infection than in the DC and healthy control (HC), while in the CSF, no significant difference was observed compared to DC. The MMP-7 serum concentration was significantly higher in children with JEV infection compared to HC, but no significant difference was observed compared to DC. MMP-7 concentration was undetectable in CSF in both groups. The TIMP-1 CSF concentration was significantly higher, while the serum concentration was significantly lower, in children with JEV infection compared to DC. No correlation was found between the levels of each biomolecule measured in CSF and serum, suggesting that the levels in CSF represent local production within the CNS rather than production in the periphery. We also observed leucocytosis, mononuclear pleocytosis and elevated protein concentrations in the CSF of children with JEV infection compared to DC.

The alterations of matrix metalloproteinase-9 in mouse brainstem during herpes simplex virus type 1-induced facial palsy

The aim of this study is to explore the changes of matrix metalloproteinase-9 (MMP9) in the mouse brainstem during the development of facial paralysis induced by herpes simplex virus type 1 (HSV-1) and the inhibitory effect of methylprednisolone sodium succinate (MPSS) on MMP9 expression. HSV-1 was inoculated into the surface of posterior auricle of mouse to establish a paralyzed animal model. The paralyzed mice were divided randomly into three groups. In one group without any treatment, mice were killed at different time points of 6 h, 1, 2, 3, and 7 days post-induction of facial paralysis; in the other two groups, mice were injected daily with MPSS and a combination of MPSS and glucocorticoid receptor blocker (RU486) for 2 days, respectively. The expression of MMP9 in the facial nucleus of brainstem was detected by Western blot, quantitative real-time polymerase chain reaction, and immunofluorescence technique. A total of 52.07 % of mice developed unilateral facial paralysis after inoculated with HSV-1. Both mRNA and protein expression of MMP9 were present at low levels in normal facial nucleus of brainstem and were increased significantly after facial paralysis with its peak time at 2 days post-induction of facial paralysis. Expression of MMP9 of paralyzed mice was inhibited by MPSS, and the inhibition could be blocked by RU486. Our findings suggest that MMP9 in mouse brainstem is involved in the evolution of facial palsy induced by HSV-1 and may play an important role in the pathogenesis of this disease. MPSS might effectively relieve HSV-1-mediated damages by inhibitory effect on expression of MMP9 in HSV-1-induced facial paralysis.

Regulation of claudins in blood-tissue barriers under physiological and pathological states

Claudins are pivotal building blocks of tight junctions that form the paracellular barrier in epithelia and endothelia. In mammals, claudins are a 27-gene family that encodes tetraspan membrane proteins, playing a crucial role in the formation and integrity of tight junctions and regulate the barrier function. Claudin isoforms are expressed in a tissue- and/or developmental stage-dependent manner. A growing body of evidence indicates that pathological states characterized by neuroinflammation, such as Alzheimer disease, multiple sclerosis, diabetic retinopathy and retinopathy of prematurity share a common feature: the barrier breakdown. This review aims integrating and summarizing the most relevant and recent work developed in the field of claudins, with particular attention to their role in blood-brain and blood-retinal barriers, as well as describing their regulation in the aforementioned human diseases.

Cytokine signaling modulates blood-brain barrier function

The blood-brain barrier (BBB) provides a vast interface for cytokines to affect CNS function. The BBB is a target for therapeutic intervention. It is essential, therefore, to understand how cytokines interact with each other at the level of the BBB and how secondary signals modulate CNS functions beyond the BBB. The interactions between cytokines and lipids, however, have not been fully addressed at the level of the BBB. Here, we summarize current understanding of the localization of cytokine receptors and transporters in specific membrane microdomains, particularly lipid rafts, on the luminal (apical) surface of the microvascular endothelial cells composing the BBB. We then illustrate the clinical context of cytokine effects on the BBB by neuroendocrine regulation and amplification of inflammatory signals. Two unusual aspects discussed are signaling crosstalk by different classes of cytokines and genetic regulation of drug efflux transporters. We also introduce a novel area of focus on how cytokines may act through nuclear hormone receptors to modulate efflux transporters and other targets. A specific example discussed is the ATP-binding cassette transporter-1 (ABCA-1) that regulates lipid metabolism. Overall, cytokine signaling at the level of the BBB is a crucial feature of the dynamic regulation that can rapidly change BBB function and affect brain health and disease.

Inhibition of proliferation, migration and proteolysis contribute to corticosterone-mediated inhibition of angiogenesis

The angiostatic nature of pharmacological doses of glucocorticoid steroids is well known. However, the consequences of pathophysiological elevation of endogenous glucocorticoids are not well established. In the current study, we hypothesized that the angiostatic effect of corticosterone, an endogenous glucocorticoid in rodents, occurs through multi-faceted alterations in skeletal muscle microvascular endothelial cell proliferation, migration, and proteolysis. Chronic corticosterone treatment significantly reduced the capillary to fiber ratio in the tibialis anterior muscle compared to that of placebo-treated rats. Corticosterone inhibited endothelial cell sprouting from capillary segments ex vivo. Similarly, 3-dimensional endothelial cell spheroids treated with corticosterone for 48 hours showed evidence of sprout regression and reduced sprout length. Endothelial cell proliferation was reduced in corticosterone treated cells, coinciding with elevated FoxO1 and reduced VEGF production. Corticosterone treated endothelial cells exhibited reduced migration, which correlated with a reduction in RhoA activity. Furthermore, corticosterone treated endothelial cells in both 3-dimensional and monolayer cultures had decreased MMP-2 production and activation resulting in decreased proteolysis by endothelial cells, limiting their angiogenic potential. Promoter assays revealed that corticosterone treatment transcriptionally repressed MMP-2, which may map to a predicted GRE between -1510 and -1386 bp of the MMP-2 promoter. Additionally, Sp1, a known transcriptional activator of MMP-2 was decreased following corticosterone treatment. This study provides new insights into the mechanisms by which pathophysiological levels of endogenous glucocorticoids may exert angiostatic effects.