Epileptiform Activity Induces Vascular Remodeling and Zonula Occludens 1 Downregulation in Organotypic Hippocampal Cultures: Role of VEGF Signaling Pathways

Abstract

Recent studies suggest that blood-brain barrier (BBB) permeability contributes to epileptogenesis in symptomatic epilepsies. We have previously described angiogenesis, aberrant vascularization, and BBB alteration in drug-refractory temporal lobe epilepsy. Here, we investigated the role of vascular endothelial growth factor (VEGF) in an in vitro integrative model of vascular remodeling induced by epileptiform activity in rat organotypic hippocampal cultures. After kainate-induced seizure-like events (SLEs), we observed an overexpression of VEGF and VEGF receptor-2 (VEGFR-2) as well as receptor activation. Vascular density and branching were significantly increased, whereas zonula occludens 1 (ZO-1), a key protein of tight junctions (TJs), was downregulated. These effects were fully prevented by VEGF neutralization. Using selective inhibitors of VEGFR-2 signaling pathways, we found that phosphatidylinositol 3-kinase is involved in cell survival, protein kinase C (PKC) in vascularization, and Src in ZO-1 regulation. Recombinant VEGF reproduced the kainate-induced vascular changes. As in the kainate model, VEGFR-2 and Src were involved in ZO-1 downregulation. These results showed that VEGF/VEGFR-2 initiates the vascular remodeling induced by SLEs and pointed out the roles of PKC in vascularization and Src in TJ dysfunction, respectively. This suggests that Src pathway could be a therapeutic target for BBB protection in epilepsies.

Novel Rat Model for Neurocysticercosis Using Taenia solium

“…28 Vascular endothelial growth factor (VEGF) expression was measured to evaluate angiogenesis. 29,30 The brain sections were washed with PBS, blocked with 5% goat normal sera in PBS 0.05% Tween 20 (PBS-T), and incubated overnight at 4 C with 1:100 rabbit anti-VEGF (Abcam, Cambridge, MA) and 5% goat normal sera in PBS-T. The sections were washed with PBS-T three times and incubated with 1:250 conjugated Alexa fluor 594 affinity-purified goat anti-rabbit IgG (Life Technologies, Woburn, MA).…”

Redistribution of PDGFRβ cells and NG2DsRed pericytes at the cerebrovasculature after status epilepticus

“…Damage of the BBB in epilepsy is accompanied by aberrant angiogenesis and the formation of leaky microvessels [4]. BBB damage allows for the extravasation of serum components into the brain parenchyma, altering the composition of the brain milieu [5].…”

Seizures as an Adverse Event of Cellular Therapy in Pediatric Neurological Disorders and its Prevention

“…Kindling models of epileptogenesis in animals suggest FGF-2 and BDNF may be the contributing factors [28]. These models also indicate that VEGF has a pivotal role to play in epileptogenesis post seizures, causing tight junction dysfunction that leads to altered blood brain barrier permeability and increased immunoglobulin G leakage and concentration in neurons [24]. Following seizures, the initial up regulation of VEGF ensures neoangiogenesis, blood flow adaptations and neuroprotection.…”

“…Neoangiogenesis triggered by BMMNCs is associated with the magnitude and rate of tissue recovery. [23] There is mobilization and enhanced homing of existing vascular endothelial progenitors from the surrounding areas that are integrated in the repair of the damage to the existing blood vessels [24,25]. Mobilization of stem cells involves the chemoattractant pathways guided by chemokines like stromal derived factor -1 (SDF-1) [26].…”