title: Ischemic neurons activate astrocytes to disrupt endothelial barrier via increasing VEGF expression.
abstract: Blood-brain barrier (BBB) disruption occurring within the first few hours of ischemic stroke onset is closely associated with hemorrhagic transformation following thrombolytic therapy. However, the mechanism of this acute BBB disruption remains unclear. In the neurovascular unit, neurons do not have direct contact with the endothelial barrier; however, they are highly sensitive and vulnerable to ischemic injury, and may act as the initiator for disrupting BBB when cerebral ischemia occurs. Herein, we employed oxygen-glucose deprivation (OGD) and an in vitro BBB system consisting of brain microvascular cells and astrocytes to test this hypothesis. Neurons (CATH.a cells) were exposed to OGD for 3-h before co-culturing with endothelial monolayer (bEnd 3 cells), or endothelial cells plus astrocytes (C8-D1A cells). Incubation of OGD-treated neurons with endothelial monolayer alone did not increase endothelial permeability. However, when astrocytes were present, the endothelial permeability was significantly increased, which was accompanied by loss of occludin and claudin-5 proteins as well as increased vascular endothelial growth factor (VEGF) secretion into the conditioned medium. Importantly, all these changes were abolished when VEGF was knocked down in astrocytes by siRNA. Our findings suggest that ischemic neurons activate astrocytes to increase VEGF production, which in turn induces endothelial barrier disruption.
authors.affiliation: Department of Geriatrics, The Second Affiliated Hospital of Medical School, Xi'an Jiaotong University, Xi'an, China.
authors.forename: Ying-Na
authors.initials: YN
authors.lastname: Li
authors.forename: Rong
authors.initials: R
authors.lastname: Pan
authors.forename: Xu-Jun
authors.initials: XJ
authors.lastname: Qin
authors.forename: Wei-Lin
authors.initials: WL
authors.lastname: Yang
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Qi
authors.forename: Wenlan
authors.initials: W
authors.lastname: Liu
authors.forename: Ke Jian
authors.initials: KJ
authors.lastname: Liu
mesh_terms: D001253:Astrocytes / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000166:cytology / Q000378:metabolism*; D015687:Cell Hypoxia / Q000502:physiology; D002478:Cells, Cultured; D018920:Coculture Techniques; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005947:Glucose / Q000172:deficiency; D006801:Humans; D009474:Neurons / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis*
chemical_list: C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D005947:Glucose; D010100:Oxygen
keywords: VEGF; astrocyte; blood-brain barrier; neuron; oxygen-glucose deprivation