Glycerophosphoinositol and dexamethasone improve transendothelial electrical resistance in an in vitro study of the blood–brain barrier

MALDI mass spectrometry imaging discloses the decline of sulfoglycosphingolipid and glycerophosphoinositol species in the brain regions related to cognition in a mouse model of Alzheimer's disease

Aging and neurodegenerative disease are accompanied by lipid perturbations in the brain. Understanding the changes in the contents and functional activity of lipids remains a challenge not only because of the many areas in which lipids perform bioactivities but also because of the technical limitations in identifying lipids and their metabolites. In the present study, we aimed to evaluate how brain lipids are altered in Alzheimer's disease (AD)-like pathology by using mass spectrometry imaging (MSI). The spatial distributions and relative abundances of lipids in the brains were compared between APP/PS1 mice and their age-matched wild-type (WT) mice by matrix-assisted laser desorption ionization (MALDI) MSI assays. The comparisons were correlated with the analysis using a spectrophotometric method to determine the relative contents of sulfatides in different brain regions. Significant changes of brain lipids between APP/PS1 and WT mice were identified: eight sulfoglycosphingolipid species, namely, sulfatides/sulfated hexosyl ceramides (ShexCer) and two glycerophosphoinositol (GroPIn) species, PI 36:4 and PI 38:4. The declines in the spatial distributions of these ShexCer and GroPIn species in the APP/PS1 mice brains were associated with learning- and memory-related brain regions. Compared with young WT mice, aged WT mice showed significant decreases in the levels of these ShexCer and GroPIn species. Our results provide technical clues for assessing the impact of brain lipid metabolism on the senescent and neurodegenerative brain. The decline in sulfatides and GroPIns may be crucial markers during brain senescence and AD pathology. Appropriate lipid complementation might be important potentials as a therapeutic strategy for AD.

Cannabinoids modulate the microbiota-gut-brain axis in HIV/SIV infection by reducing neuroinflammation and dysbiosis while concurrently elevating endocannabinoid and indole-3-propionate levels

BACKGROUND

Although the advent of combination anti-retroviral therapy (cART) has transformed HIV into a manageable chronic disease, an estimated 30-50% of people living with HIV (PLWH) exhibit cognitive and motor deficits collectively known as HIV-associated neurocognitive disorders (HAND). A key driver of HAND neuropathology is chronic neuroinflammation, where proinflammatory mediators produced by activated microglia and macrophages are thought to inflict neuronal injury and loss. Moreover, the dysregulation of the microbiota-gut-brain axis (MGBA) in PLWH, consequent to gastrointestinal dysfunction and dysbiosis, can lead to neuroinflammation and persistent cognitive impairment, which underscores the need for new interventions.

METHODS

We performed RNA-seq and microRNA profiling in basal ganglia (BG), metabolomics (plasma) and shotgun metagenomic sequencing (colon contents) in uninfected and SIV-infected rhesus macaques (RMs) administered vehicle (VEH/SIV) or delta-9-tetrahydrocannabinol (THC) (THC/SIV).

RESULTS

Long-term, low-dose THC reduced neuroinflammation and dysbiosis and significantly increased plasma endocannabinoid, endocannabinoid-like, glycerophospholipid and indole-3-propionate levels in chronically SIV-infected RMs. Chronic THC potently blocked the upregulation of genes associated with type-I interferon responses (NLRC5, CCL2, CXCL10, IRF1, IRF7, STAT2, BST2), excitotoxicity (SLC7A11), and enhanced protein expression of WFS1 (endoplasmic reticulum stress) and CRYM (oxidative stress) in BG. Additionally, THC successfully countered miR-142-3p-mediated suppression of WFS1 protein expression via a cannabinoid receptor-1-mediated mechanism in HCN2 neuronal cells. Most importantly, THC significantly increased the relative abundance of Firmicutes and Clostridia including indole-3-propionate (C. botulinum, C. paraputrificum, and C. cadaveris) and butyrate (C. butyricum, Faecalibacterium prausnitzii and Butyricicoccus pullicaecorum) producers in colonic contents.

CONCLUSION

This study demonstrates the potential of long-term, low-dose THC to positively modulate the MGBA by reducing neuroinflammation, enhancing endocannabinoid levels and promoting the growth of gut bacterial species that produce neuroprotective metabolites, like indole-3-propionate. The findings from this study may benefit not only PLWH on cART, but also those with no access to cART and more importantly, those who fail to suppress the virus under cART.

2-O-Acetyl-3,4,5,6-tetra-O-benzyl-d-myo-inosityl diphenylphosphate: A new useful intermediate to inositol phosphate and phospholipids

Inositol phosphates and inositol phospholipids are ubiquitous in biochemistry and play a central role in cell signaling and regulation events. For this reason, their synthesis has attracted widespread interest. This paper describes the preparation of a new optically active inositol phosphate derivative, 2‐O‐acetyl‐3,4,5,6‐tetra‐O‐benzyl‐d‐myo‐inosityl diphenylphosphate (6), and its characterization by spectroscopic methods. Compound (6) represents a useful intermediate for the preparation of inositol phosphate and phospholipids, in particular of glycerophosphoinositol (GPI), a natural anti‐inflammatory agent.

Research on Mechanism of miR-106a Nanoparticles Carrying Dexmedetomidine in Regulating Recovery and Metabolism of Nerve Cells in Hypoxia-Reoxygenation Injury

We studied the mechanism of miR-106a nanoparticles carrying dexmedetomidine (DEX) in regulating the recovery and metabolism of nerve cells in hypoxia-reoxygenation injury. Hippocampus neuron model in hypoxia-reoxygenation injury was prepared in vitro. Study groups were randomly divided into control set, ischemic reperfusion (IR) set, dexmedetomidine (DEX) set, miR-106a-nanoparticles (NPs) set and set of dexmedetomidine (DEX) and miR-106a-NPs. We studied miR-106a expression, proliferative and apoptotic activity, secretion of IL-6 and tumor necrosis factor (TNF)-α, quantity of Phosphocreatine (PCr), adenosine triphosphate (ATP) and total adenine nucleotide, and also content of reactive oxygen species (ROS) and superoxide dismutases (SOD). Expressions of of Bax, Bcl-2 and NF-κB were also detected. Results showed that the expression of miR-106a in hippocampus neuron was reduced, while proliferation was reduced and apoptotic activity was increased. The secretions of IL-6 and TNF-α were increased, while the quantities of Phosphocreatine (PCr), adenosine triphosphate (ATP) and total adenine nucleotide were reduced. Bax expression was also increased and Bcl-2 expression was reduced. Moreover, ROS content was increased and SOD activity was reduced, while the NF-κB presentation was increased. The above-mentioned changes could be reversed in IR set, DEX set and miR-106a-NPs set. The action was more notable in the DEX and miR-106a-NPs sets. Finally, the proliferation in hippocampus neuron in hypoxia-reoxygenation injury could be prompted and apoptosis could be restrained by DEX and miR-106a-NPs. The secretion of inflammatory factors could be restrained through restraining the inflammatory pathway and oxidative stress. The energy metabolism could therefore be improved effectively and recovery of nerve cells in HBI could be improved.

Ocular Surface Failure in Urban Syndrome

BACKGROUND

Nowadays, the continuous increase in air pollution has significantly changed air quality, leading to the onset of the so-called urban syndrome (US), an allergic-like conjunctivitis triggered by pollutants. These patients are characterized by persistent dysregulation of ocular surface para-inflammation, causing chronic low-grade inflammation and ocular discomfort, with significant consequences for occupational health and job productivity prospects. This study aims to investigate the effects of topical glycerophosphoinositol (GPI) eye drops on the signs and symptoms of US.

METHODS

A multicenter prospective open interventional study was performed. Patients affected by US, enrolled from occupational medicine clinics, were treated with eye drops containing 0.001% GPI in 0.2% HA vehicle three times a day. Ocular surface disease index (OSDI), tear break-up time (T-BUT), Schirmer test, Oxford score, hyperemia and ocular surface symptoms were recorded at patient enrolment (T0), after 1 week (T1) and after 1 month (T2) of treatment.

RESULTS

A total of 113 consecutive patients (226 eyes) were included. OSDI score displayed a significant improvement after one week (T0: 39.9 ± 19, T1: 20.8 ± 17.9, T2: 18.4 ± 15.6, p < 0.0001); T-BUT (T0: 5.2 ± 2, T1: 7.7 ± 2.2, T2: 9.7 ± 1.8, p < 0.0001) and Schirmer Test (T0: 6.6 ± 2.4, T1: 9.7 ± 2.7, T2: 12.6 ± 2.6, p < 0.0001) progressively improved from T0 to T2.

CONCLUSIONS

trice-daily topic instillation of 0.001% GPI in 0.02% HA vehicle resulted an effective and well tolerated treatment in US patients.

Xiao-Yao-San reduces blood-brain barrier injury induced by chronic stress in vitro and vivo via glucocorticoid receptor-mediated upregulation of Occludin

Blood-brain barrier (BBB) is a barrier which maintains the material exchange balance of brain microenvironment and could be destroyed by chronic stress (CS). Glucocorticoids (GCs) can mimic the chronic stress induced damage to BBB. GCs induced BBB trauma models in vitro and in vivo to explore the effects of the traditional medicine Xiao-Yao-San (XYS). In this research, we found CS could injure the BBB to change the biochemical index, which could be reversed by XYS in vitro. The abilities of cell proliferation, invasion, and the expression of tight junction related genes (Occludin, Claudin, JAM-1 and ZO-1) were suppressed by CS and the trauma could be reversed by XYS partly. It was showed that GRs interacted with Occludin directly and inhibited Occluding expression. In rats BBB trauma model, the GC content was deceased and BBB permeability was repaired by XYS. The expression of Occludin, Claudin, JAM-1 and ZO-1 were increased in the treatment of XYS. In our research, it shown that XYS affect the content of the GC and GR which interacted with Occludin directly for the first time. In addition, we also found that XYS could reduce BBB injury induced by CS via GR in BBB model in vitro. Therefore, it proves that XYS is a potential BBB repair medicine and may help to elucidate mechanism of brain pathology.

The natural phosphoinositide derivative glycerophosphoinositol inhibits the lipopolysaccharide-induced inflammatory and thrombotic responses

Inflammatory responses are elicited through lipid products of phospholipase A2 activity that acts on the membrane phospholipids, including the phosphoinositides, to form the proinflammatory arachidonic acid and, in parallel, the glycerophosphoinositols. Here, we investigate the role of the glycerophosphoinositol in the inflammatory response. We show that it is part of a negative feedback loop that limits proinflammatory and prothrombotic responses in human monocytes stimulated with lipopolysaccharide. This inhibition is exerted both on the signaling cascade initiated by the lipopolysaccharide with the glycerophosphoinositol-dependent decrease in IκB kinase α/β, p38, JNK, and Erk1/2 kinase phosphorylation and at the nuclear level with decreased NF-κB translocation and binding to inflammatory gene promoters. In a model of endotoxemia in the mouse, treatment with glycerophosphoinositol reduced TNF-α synthesis, which supports the concept that glycerophosphoinositol inhibits the de novo synthesis of proinflammatory and prothrombotic compounds and might thus have a role as an endogenous mediator in the resolution of inflammation. As indicated, this effect of glycerophosphoinositol can also be exploited in the treatment of manifestations of severe inflammation by exogenous administration of the compound.

Dexamethasone potentiates in vitro blood-brain barrier recovery after primary blast injury by glucocorticoid receptor-mediated upregulation of ZO-1 tight junction protein

Owing to the frequent incidence of blast-induced traumatic brain injury (bTBI) in recent military conflicts, there is an urgent need to develop effective therapies for bTBI-related pathologies. Blood-brain barrier (BBB) breakdown has been reported to occur after primary blast exposure, making restoration of BBB function and integrity a promising therapeutic target. We tested the hypothesis that treatment with dexamethasone (DEX) after primary blast injury potentiates recovery of an in vitro BBB model consisting of mouse brain endothelial cells (bEnd.3). DEX treatment resulted in complete recovery of transendothelial electrical resistance and hydraulic conductivity 1 day after injury, compared with 3 days for vehicle-treated injured cultures. Administration of RU486 (mifepristone) inhibited effects of DEX, confirming that barrier restoration was mediated by glucocorticoid receptor signaling. Potentiated recovery with DEX treatment was accompanied by stronger zonula occludens (ZO)-1 tight junction immunostaining and expression, suggesting that increased ZO-1 expression was a structural correlate to BBB recovery after blast. Interestingly, augmented ZO-1 protein expression was associated with specific upregulation of the α(+) isoform but not the α(-) isoform. This is the first study to provide a mechanistic basis for potentiated functional recovery of an in vitro BBB model because of glucocorticoid treatment after primary blast injury.

Inhibition of prolactin with bromocriptine for 28days increases blood-brain barrier permeability in the rat

The blood-brain barrier (BBB) is necessary for the proper function of the brain. Its maintenance is regulated by endogenous factors. Recent evidences suggest prolactin (PRL) regulates the BBB properties in vitro, nevertheless no evidence of these effects have been reported in vivo. The aim of this study was to evaluate the role of PRL in the maintenance of the BBB in the rat. Male Wistar rats were treated with Bromocriptine (Bromo) to inhibit PRL production for 28days in the absence or presence of lipopolysaccharide (LPS). BBB permeability was evaluated through the Evans Blue dye and fluorescein-dextran extravasation as well as through edema formation. The expression of claudin-5, occludin, glial fibrillary acidic protein (GFAP) and the PRL receptor (PRLR) was evaluated through western blot. Bromo reduced the physiological levels of PRL at 28days. At the same time, Bromo increased BBB permeability and edema formation associated with a decrement in claudin-5 and occludin and potentiated the increase in BBB permeability induced by LPS. However, no neuroinflammation was detected, since the expression of GFAP was unchanged, as well as the expression of the PRLR. These data provide the first evidence that inhibition of PRL with Bromo affects the maintenance of the BBB through modulating the expression of tight junction proteins in vivo.

A role for inflammation in status epilepticus is revealed by a review of current therapeutic approaches

A significant number of patients with epilepsy fail to respond to currently available antiepileptic drugs. This suggests a need for alternative approaches to reduce the occurrence of seizures in these patients. Recent data have shown that in addition to well-known neuronal mechanism, seizures may be a consequence of misguided inflammatory response and blood-brain barrier disruption. Both peripheral and brain proinflammatory events have been demonstrated to govern the onset of status epilepticus. Evidence deriving from the experimental and clinical realms supports the notion that a role for proinflammatory and cerebrovascular events in seizure disorders is broader than previously suspected. As a result, methods to pharmacologically reduce blood-brain barrier permeability and reduce inflammation have emerged as means to reduce seizure burden. For instance, corticosteroids have been shown to be beneficial and the same agents may be able to further reduce seizure burden in conjunction with currently prescribed antiepileptic drugs.

Acute mountain sickness, inflammation, and permeability: new insights from a blood biomarker study

The pathophysiology of acute mountain sickness (AMS) is unknown. One hypothesis is that hypoxia induces biochemical changes that disrupt the blood-brain barrier (BBB) and, subsequently, lead to the development of cerebral edema and the defining symptoms of AMS. This study explores the relationship between AMS and biomarkers thought to protect against or contribute to BBB disruption. Twenty healthy volunteers participated in a series of hypobaric hypoxia trials distinguished by pretreatment with placebo, acetazolamide (250 mg), or dexamethasone (4 mg), administered using a randomized, double-blind, placebo-controlled, crossover design. Each trial included peripheral blood sampling and AMS assessment before (-15 and 0 h) and during (0.5, 4, and 9 h) a 10-h hypoxic exposure (barometric pressure = 425 mmHg). Anti-inflammatory and/or anti-permeability [interleukin (IL)-1 receptor agonist (IL-1RA), heat shock protein (HSP)-70, and adrenomedullin], proinflammatory (IL-6, IL-8, IL-2, IL-1β, and substance P), angiogenic, or chemotactic biomarkers (macrophage inflammatory protein-1β, VEGF, TNF-α, monocyte chemotactic protein-1, and matrix metalloproteinase-9) were assessed. AMS-resistant subjects had higher IL-1RA (4 and 9 h and overall), HSP-70 (0 h and overall), and adrenomedullin (overall) compared with AMS-susceptible subjects. Acetazolamide raised IL-1RA and HSP-70 compared with placebo in AMS-susceptible subjects. Dexamethasone also increased HSP-70 and adrenomedullin in AMS-susceptible subjects. Macrophage inflammatory protein-1β was higher in AMS-susceptible than AMS-resistant subjects after 4 h of hypoxia; dexamethasone minimized this difference. Other biomarkers were unrelated to AMS. Resistance to AMS was accompanied by a marked anti-inflammatory and/or anti-permeability response that may have prevented downstream pathophysiological events leading to AMS. Conversely, AMS susceptibility does not appear to be related to an exaggerated inflammatory response.

Efficacy of anti-inflammatory therapy in a model of acute seizures and in a population of pediatric drug resistant epileptics

Targeting pro-inflammatory events to reduce seizures is gaining momentum. Experimentally, antagonism of inflammatory processes and of blood-brain barrier (BBB) damage has been demonstrated to be beneficial in reducing status epilepticus (SE). Clinically, a role of inflammation in the pathophysiology of drug resistant epilepsies is suspected. However, the use anti-inflammatory drug such as glucocorticosteroids (GCs) is limited to selected pediatric epileptic syndromes and spasms. Lack of animal data may be one of the reasons for the limited use of GCs in epilepsy. We evaluated the effect of the CG dexamethasone in reducing the onset and the severity of pilocarpine SE in rats. We assessed BBB integrity by measuring serum S100β and Evans Blue brain extravasation. Electrophysiological monitoring and hematologic measurements (WBCs and IL-1β) were performed. We reviewed the effect of add on dexamethasone treatment on a population of pediatric patients affected by drug resistant epilepsy. We excluded subjects affected by West, Landau-Kleffner or Lennox-Gastaut syndromes and Rasmussen encephalitis, known to respond to GCs or adrenocorticotropic hormone (ACTH). The effect of two additional GCs, methylprednisolone and hydrocortisone, was also reviewed in this population. When dexamethasone treatment preceded exposure to the convulsive agent pilocarpine, the number of rats developing status epilepticus (SE) was reduced. When SE developed, the time-to-onset was significantly delayed compared to pilocarpine alone and mortality associated with pilocarpine-SE was abolished. Dexamethasone significantly protected the BBB from damage. The clinical study included pediatric drug resistant epileptic subjects receiving add on GC treatments. Decreased seizure frequency (≥50%) or interruption of status epilepticus was observed in the majority of the subjects, regardless of the underlying pathology. Our experimental results point to a seizure-reducing effect of dexamethasone. The mechanism encompasses improvement of BBB integrity. Our results also suggest that add on GCs could be of efficacy in controlling pediatric drug resistant seizures.

High dose methotrexate for pediatric high grade glioma: results of the HIT-GBM-D pilot study

We conducted a phase II study to test methotrexate (5 g/m(2)), as a single agent prior to radiochemotherapy for pediatric high-grade glioma and diffuse intrinsic pontine glioma. Thirty patients (19 male, median age 10.8) were enrolled. Tumors were located as follows: cortex 10, pons 7, other 13. Tumor resection was classified as gross total in 6, subtotal in 6, partial in 4, biopsy in 11 and not performed in 3. WHO grading of the histology was: IV: 11, III: 12 and II: 3. Patients received methotrexate 5 g/m(2) in 24-hour infusions on days 1 and 15. Subsequently 54 Gy radiation was administered with simultaneous chemotherapy including cisplatin, etoposide, vincristine and ifosfamide as previously described. Eight 6-weeks cycles of maintenance chemotherapy consisted of vincristine 1.5 mg/m(2) on days 1, 8 and 15; lomustine 100 mg/m(2) on day 2 and prednisone 40 mg/kg on days 1-17. Event-free survival rates in the whole group of 30 patients were: 43, 20, and 13% after 1, 2 and 5 years, respectively. The response evaluation after methotrexate was available in 19 of the 24 patients who started treatment with measurable disease: CR: 0, PR: 1, SD 18, PD: 0. After radiochemotherapy the response of 24 patients with measurable disease was CR: 1, PR 10, SD 12, PD 1. Both response and event-free survival were superior to the control group of 330 patients treated in various protocols of the same cooperative group. In subgroup analyses the use of dexamethasone during early treatment was linked to poor event free survival. Giving two cycles of high-dose methotrexate prior to radiochemotherapy was feasible, and the approach was taken forward to a randomized phase III trial.

Effects of immunomodulatory and organism-associated molecules on the permeability of an in vitro blood-brain barrier model to amphotericin B and fluconazole

Amphotericin B (AMB) is used to treat fungal infections of the central nervous system (CNS). However, AMB shows poor penetration into the CNS and little is known about the factors affecting its permeation through the blood-brain barrier (BBB). Therefore, we studied immunomodulatory and organism-associated molecules affecting the permeability of an in vitro BBB model to AMB. We examined the effects of interleukin-1 beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), lipopolysaccharide (LPS), lipoteichoic acid (LTA), zymosan (ZYM), dexamethasone (DEX), cyclosporine, and tacrolimus on transendothelial electrical resistance (TEER); endothelial tight junctions; filamentous actin; and permeability to deoxycholate AMB (DAMB), liposomal AMB (LAMB), and fluconazole. Proinflammatory cytokines and organism-associated molecules significantly decreased the mean TEER by 40.7 to 100% (P < or = 0.004). DEX increased the mean TEER by 18.2 to 26.4% (P < or = 0.04). TNF-alpha and LPS increased the permeability to AMB by 8.2 to 14.5% compared to that for the controls (1.1 to 2.4%) (P < or = 0.04). None of the other molecules affected the model's permeability to AMB. By comparison, the BBB model's permeability to fluconazole was >78% under all conditions studied, without significant differences between the controls and the experimental groups. LPS and TNF-alpha decreased tight-junction protein zona occludens 1 (ZO-1) between endothelial cells. In conclusion, IL-1beta, ZYM, and LTA increased the permeability of the BBB to small ions but not to AMB, whereas TNF-alpha and LPS, which disrupted the endothelial layer integrity, increased the permeability to AMB.

Management of the patient with medically refractory epilepsy

Epilepsy imposes a significant clinical, epidemiologic and economic burden on societies throughout the world. Despite the development of more than ten new antiepileptic drugs over the past 15 years, approximately a third of patients with epilepsy remain resistant to pharmacotherapy. Individuals who fail to respond, or respond only partially, continue to have incapacitating seizures. Managing patients with medically refractory epilepsy is challenging and requires a structured multidisciplinary approach in specialized clinics. If the problems related to drug resistance could be resolved, even in part, by improving the pharmacokinetic profile of existing drugs, the economic savings would be remarkable and the time required to design drugs that achieve seizure control would be shorter than the discovery of new targets and molecules was required. A promising approach is the use of corticosteroids that may have a dual beneficial effect. Resective brain surgery remains the ultimate and highly successful approach to multiple drug resistance in epileptic patients.

The glycerophosphoinositols: cellular metabolism and biological functions

The glycerophosphoinositols are cellular products of phospholipase A(2) and lysolipase activities on the membrane phosphoinositides. Their intracellular concentrations can vary upon oncogenic transformation, cell differentiation and hormonal stimulation. Specific glycerophosphodiester phosphodiesterases are involved in their catabolism, which, as with their formation, is under hormonal regulation. With their mechanisms of action including modulation of adenylyl cyclase, intracellular calcium levels, and Rho-GTPases, the glycerophosphoinositols have diverse effects in multiple cell types: induction of cell proliferation in thyroid cells; modulation of actin cytoskeleton organisation in fibroblasts; and reduction of the invasive potential of tumour cell lines. More recent investigations include their effects in inflammatory and immune responses. Indeed, the glycerophosphoinositols enhance cytokine-dependent chemotaxis in T-lymphocytes induced by SDF-1alpha-receptor activation, indicating roles for these compounds as modulators of T-cell signalling and T-cell responses.

Antagonism of peripheral inflammation reduces the severity of status epilepticus

Status epilepticus (SE) is one of the most serious manifestations of epilepsy. Systemic inflammation and damage of blood-brain barrier (BBB) are etiologic cofactors in the pathogenesis of pilocarpine SE while acute osmotic disruption of the BBB is sufficient to elicit seizures. Whether an inflammatory-vascular-BBB mechanism could apply to the lithium-pilocarpine model is unknown. LiCl facilitated seizures induced by low-dose pilocarpine by activation of circulating T-lymphocytes and mononuclear cells. Serum IL-1beta levels increased and BBB damage occurred concurrently to increased theta EEG activity. These events occurred prior to SE induced by cholinergic exposure. SE was elicited by lithium and pilocarpine irrespective of their sequence of administration supporting a common pathogenetic mechanism. Since IL-1beta is an etiologic trigger for BBB breakdown and its serum elevation occurs before onset of SE early after LiCl and pilocarpine injections, we tested the hypothesis that intravenous administration of IL-1 receptor antagonists (IL-1ra) may prevent pilocarpine-induced seizures. Animals pre-treated with IL-1ra exhibited significant reduction of SE onset and of BBB damage. Our data support the concept of targeting systemic inflammation and BBB for the prevention of status epilepticus.

Dexamethasone enhances calcium-activated potassium channel expression in blood-brain tumor barrier in a rat brain tumor model

This study was performed to determine whether dexamethasone (DEX) had an effect on calcium-activated potassium channels (KCa channels) in blood-brain tumor barrier (BTB).Using a rat brain glioma model, we found that the expression of KCa channels protein was significantly increased in brain tumor tissue. And bradykinin-induced increase of KCa channels protein was further enhanced after DEX pretreatment for 3 days. In addition, DEX pretreatment enhanced bradykinin-mediated up-regulation of the density of IKCa in the rat brain C6 cells in vitro BTB. Bradykinin markedly increased BTB permeability independent of DEX pretreatment. All of these results strongly suggest that DEX could regulate the target in the transcellular pathway of BTB-KCa channels.

Dexamethasone enhances adenosine 5'-triphosphate-sensitive potassium channel expression in the blood-brain tumor barrier in a rat brain tumor model

This study was performed to determine whether dexamethasone (DEX) had an effect on ATP-sensitive potassium channels (K(ATP) channels) in blood-brain tumor barrier (BTB). Using a rat brain glioma model, we found that DEX could significantly increase the expression of K(ATP) channels protein at tumor sites. And bradykinin-induced increase of K(ATP) channels protein was further enhanced after DEX pretreatment for 3 consecutive days via Western blots and immunohistochemistry methods. In addition, DEX pretreatment enhanced bradykinin-mediated increase of the density of I(KATP) in the cultured rat C6 glioma cells using the patch-clamp technique in a whole-cell configuration. DEX significantly decreased the BTB permeability, but it did not reduce bradykinin-mediated BTB permeability increase, which were significantly attenuated by the K(ATP) channel antagonist glibenclamide. This led to the conclusion that DEX-mediated change in BTB permeability is, at least partly, due to accelerated formation of K(ATP) channel, an important target in the biochemical regulation of this process.

Effects of maternal treatment with corticosteroids on tight junction protein expression in the cerebral cortex of the ovine fetus with and without exposure to in utero brain ischemia

Maternal treatment with corticosteroids reduces blood-brain barrier permeability in premature ovine fetuses and the incidence of intraventricular hemorrhage in premature infants. We tested the hypothesis that maternally administered corticosteroids increase the expression of tight junction (TJ) proteins in the cerebral cortex of ovine fetuses with and without exposure to in utero brain ischemia. Fetuses at 80% of gestation were studied 18 h after the last of four 4-6 mg dexamethasone or placebo injections were given over 48 h to ewes. Groups were placebo/control, dexamethasone/control, placebo/ischemic, and dexamethasone/ischemic. Ischemia consisted of 30 min of fetal carotid artery occlusion and 72 h of reperfusion. Cerebral cortex was snap frozen. Western immunoblot was used to measure the protein expression of occludin, claudin-1, claudin-5, zonula occludens (ZO)-1, and ZO-2, and a TJ accessory protein annexin-ll. Occludin and annexin-ll protein expression were 48% and 58% higher (P<0.05) in the dexamethasone/ischemic than placebo/control group, respectively. Claudin-5 protein expression was 69% and 73% higher (P<0.05) in the placebo/ischemic and dexamethasone/ischemic than placebo/control group. Claudin-1 expression did not differ among groups. ZO-1 protein expression was 25%, 40%, and 55% lower in the dexamethasone/control, placebo/ischemic, and dexamethasone/ischemic than placebo/control group, respectively. ZO-2 expression was 45% and 70% lower (P<0.01) in the placebo/ischemic and dexamethasone/ischemic than placebo/control group. We conclude that maternal corticosteroid treatment differentially regulates the expression of component proteins of TJs in the cerebral cortex of fetuses exposed to brain ischemia. The functional significance of this differential regulation warrants further investigation.

A functional in vitro model of rat blood-brain barrier for molecular analysis of efflux transporters

Physiological studies of the blood-brain barrier (BBB) are often performed in rats. We describe the functional characterization of a reproducible in vitro model of the rat BBB and its validation for investigating mechanisms involved in BBB regulation. Puromycin-purified primary cultures of brain endothelial cells, co-cultured with astrocytes in the presence of hydrocortisone (HC) and cAMP, presented low sucrose permeability (< or =0.1 x 10(-3) cm/min) and high transendothelial electrical resistance (> or =270 Omega cm(2)). Expression of specific BBB markers and their transcripts was detected by immunostaining and RT-PCR, respectively: tight junction proteins (claudin-3 and -5, ZO-1 and occludin) and transporters (P-gp, Bcrp and Oatp-2). RT-PCR experiments demonstrated a role of treatment by astrocytes, HC and cAMP in regulation of the transcript level of tight junction proteins (claudin-5 and ZO-1) as well as transporters (Mdr1a, Mrp3, Mrp4, Bcrp, Glut-1), while transcript level of Mdr1b was significantly decreased. The functionality of efflux pumps (P-gp, Mrps and Bcrp) was demonstrated in the presence of specific inhibitors (PSC833, MK571 or Ko143, respectively) by (i) assessing the uptake of the common substrates rhodamine 123 and daunorubicin and (ii) evaluating apical to basolateral and basolateral to apical polarized transport of daunorubicin. In addition, a good correlation (R=0.94) was obtained between the permeability coefficients of a series of compounds of various lipophilicity and their corresponding in vivo rodent blood-brain transfer coefficients. Taken together, our results provide compelling evidence that puromycin-purified rat brain endothelial cells constitute a reliable model of the rat BBB for physiological and pharmacological characterization of BBB transporters.

Dexamethasone treatment modulates aquaporin-4 expression after intracerebral hemorrhage in rats

This study investigated whether dexamethasone (DEX) treatment could regulate the expression of aquaporin-4 (AQP4) in rats with intracerebral hemorrhage (ICH). The results demonstrated that DEX significantly reduced AQP4 mRNA level in the perihematomal area compared with control group, but it increased the level in the brain area surrounding the third ventricle at day 1 post-ICH. There was no difference in AQP4 protein levels between DEX group and control group at the two above-mentioned brain regions at day 1 after ICH. The changes in AQP4 protein induced by DEX were marked at day 3 following surgery and still lasted at day 5 post-ICH, which were accompanied by a reduction of brain edema. Our results demonstrated that the expression of AQP4 protein after ICH was region-specific, time-dependent, and also indicated that DEX-induced cerebral edema clearance was correlated with the regulation of AQP4 expression in different brain regions.

Development of an in vitro blood-brain barrier model to study the effects of endosulfan on the permeability of tight junctions and a comparative study of the cytotoxic effects of endosulfan on rat and human glial and neuronal cell cultures

Endosulfan, an organochlorine (OC) insecticide that belongs to the cyclodiene group, is one of the most commonly used pesticides to control pests in vegetables, cotton, and fruits. Porcine brain microvascular endothelial cells were used to develop a model to study the effects of endosulfan on the permeability of tight junctions in the blood-brain barrier (BBB). BBB permeability, measured as transendothelial electrical resistance, decreased in a dose- and time-dependent manner when treated with alpha-endosulfan, beta-endosulfan, or endosulfan sulfate. Cytotoxicity testing revealed that the three endosulfans did not cause cell death at concentrations of 10 microM and below. The ratio of the average permeability of the filter-grown endothelial cell monolayer to 14C-endosulfan (Pe) going from the outer to the inner compartments with that going from the inner to the outer compartments was approximately 1:1.2-2.1 after exposure to concentrations of 0.01-10 microM. alpha-Endosulfan, beta-endosulfan, and endosulfan sulfate had cytotoxic effects on rat glial (C6) and neuronal (PC12) cell cultures as well as on human glial (CCF-STTG1) and neuronal (NT2) cell cultures. The effects of alpha-endosulfan were highly selective, with a wide range of LC50 values found in the different cultures, ranging from 11.2 microM for CCF-STTG1 cells to 48.0 microM for PC12 cells. In contrast, selective neurotoxicity was not so manifest in glial and neuronal cell cultures after exposure to endosulfan sulfate, as LC50 values were in the range of 10.4-21.6 microM. CCF-STTG1 cells were more sensitive to alpha-endosulfan and endosulfan sulfate, whereas NT2 cells were more sensitive to beta-endosulfan.

Differential action of steroid hormones on human endothelium

The action of glucocorticoids on vascular permeability is well established. However, little is known about the action of mineralocorticoids on the structure and function of blood vessels. As endothelial cells are targets for both glucocorticoids and mineralocorticoids, we exposed human umbilical vein endothelial cells to both types of steroids. Aldosterone (mineralocorticoid) and dexamethasone (glucocorticoid) were applied for 3 days in culture before measurements of transendothelial ion and macromolecule permeability, apical cell surface and cell stiffness were taken. Transendothelial ion permeability was measured with electrical cell impedance sensing, macromolecule permeability with fluorescence-labeled dextran and apical cell membrane surface by three-dimensional AFM imaging. Cell stiffness was measured using the AFM scanning tip as a mechanical nanosensor. We found that aldosterone increased both apical cell surface and apical cell stiffness significantly, while transendothelial permeability remained unaffected. By contrast, dexamethasone significantly decreased ion and macromolecule permeability, while apical cell surface and cell stiffness did not change. Specific receptor antagonists for dexamethasone (RU486) and aldosterone (spironolactone) prevented the observed responses. We conclude that glucocorticoids strengthen cell-to-cell contacts (`peripheral action'), whereas mineralocorticoids enlarge and stiffen cells (`central action'). This could explain the dexamethasone-mediated retention of fluid in the vascular system, and endothelial dysfunction in states of hyperaldosteronism.

Astrocyte-endothelial interactions at the blood-brain barrier

The blood-brain barrier, which is formed by the endothelial cells that line cerebral microvessels, has an important role in maintaining a precisely regulated microenvironment for reliable neuronal signalling. At present, there is great interest in the association of brain microvessels, astrocytes and neurons to form functional 'neurovascular units', and recent studies have highlighted the importance of brain endothelial cells in this modular organization. Here, we explore specific interactions between the brain endothelium, astrocytes and neurons that may regulate blood-brain barrier function. An understanding of how these interactions are disturbed in pathological conditions could lead to the development of new protective and restorative therapies.

Serial Audiometry in a Clinical Trial of AIED Treatment

OBJECTIVE

We analyzed pure-tone and speech audiometric results from a prospective trial of anti-inflammatory treatment of subjects with active autoimmune inner ear disease (AIED). We sought to characterize the pattern and size of the treatment effect as reflected in clinical audiometry and to identify audiometric predictors of response to steroid treatment of AIED.

SUBJECTS

Adult participants demonstrated clinically established criteria for AIED (n = 116). Eligibility required audiometric evidence of active AIED as indicated by idiopathic sensorineural hearing loss with threshold elevations within 3 months of enrollment.

METHODS

We evaluated audiometric changes after 4 weeks of treatment with pharmacologic doses (60 mg/day) of prednisone. We examined the relationship between audiometric pure-tone thresholds at baseline and changes in word intelligibility score (WIS) using parametric and nonparametric analyses. Magnitudes of change were assessed using independent or paired t-tests. Separate analyses were performed on subgroups that did or did not show improved WIS score with steroid treatment.

RESULTS

Overall mean pure-tone averages improved from baseline to closeout of prednisone treatment in better hearing ears from 52.4 to 48.3 dB (p < .0001). Mean WIS improved in the better ear from 71.4% to 78.1% (p < .0001). Of pure-tone measures, only the six-tone average showed significant correlation with both the absolute improvements in WIS and with the percentage change in WIS after treatment. Individual frequencies at baseline showed no significant relationship with changes in WIS score after treatment. In 69 (59.5%) of 116 subjects, WIS improved (range, 2-80%) in the better ear. In these subjects, the baseline pure-tone thresholds and pure-tone averages correlated significantly and positively with improvement in WIS.

CONCLUSIONS

Steroid treatment in AIED-mediated hearing loss produce variable but significant hearing gains. Neither a focal, cochleotopic region of greatest vulnerability to AIED nor frequency-specific amenability to treatment were evident. We did observe that analysis of predictors and the degree of treatment effect vary with different approaches to measuring change in the WIS. Depending on the approach adopted, the size of the treatment effect may be greatest across intermediate hearing levels at baseline. These observations offer an audiometric database that may enable greater precision in judging clinically meaningful parameters for future studies of AIED treatment and other interventions for sensorineural hearing loss.

Puromycin-based purification of rat brain capillary endothelial cell cultures. Effect on the expression of blood-brain barrier-specific properties

One of the main difficulties with primary rat brain endothelial cell (RBEC) cultures is obtaining pure cultures. The variation in purity limits the achievement of in vitro models of the rat blood-brain barrier. As P-glycoprotein expression is known to be much higher in RBECs than in any contaminating cells, we have tested the effect of five P-glycoprotein substrates (vincristine, vinblastine, colchicine, puromycin and doxorubicin) on RBEC cultures, assuming that RBECs would resist the treatment with these toxic compounds whereas contaminating cells would not. Treatment with either 4 microg/mL puromycin for the first 2 days of culture or 3 microg/mL puromycin for the first 3 days showed the best results without causing toxicity to the cells. Transendothelial electrical resistance was significantly increased in cell monolayers treated with puromycin compared with untreated cell monolayers. When cocultured with astrocytes in the presence of cAMP, the puromycin-treated RBEC monolayer showed a highly reduced permeability to sodium fluorescein (down to 0.75 x 10(-6) cm/s) and a high electrical resistance (up to 500 Omega x cm(2)). In conclusion, this method of RBEC purification will allow the production of in vitro models of the rat blood-brain barrier for cellular and molecular biology studies as well as pharmacological investigations.