There is increasing evidence that inflammatory processes play a pivotal role in the pathophysiology of ischaemic brain injury. Cerebrovascular endothelial cells that form the blood-brain barrier are critical for maintaining brain homeostasis, however, during cerebral ischaemia they contribute to the post-ischaemic inflammatory responses. It is not yet fully understood how different cerebral cells interact during this inflammatory response. This study aimed to test the hypothesis that oxygen-glucose deprivation (OGD) induces the inflammatory activation of the cerebrovascular endothelium and glial cells in vitro and that intercommunication between these cells regulate their responses to OGD. Primary murine brain endothelial cells (MBECs) monocultures, murine mixed-glial monocultures and MBEC-glial co-cultures were exposed to OGD for up to 24 hours (h), then reperfused cultures were returned to normoxia for a further 24 hours. MBECs and glia remained viable over a 24 h OGD exposure and during reperfusion. OGD induced a time-dependent increase in MBEC glucose transporter 1 (GLUT-1) expression but a time-dependent decline in expression and secretion of monocyte chemoattractant protein-1 (MCP-1). A significant increase in keratinocyte-derived chemokine (KC) secretion by MBEC monocultures was observed during reperfusion after prolonged exposure (18-24 h) to OGD whereas, KC secretion by co-cultured MBECs was increased during reperfusion after short exposure (4 h) to OGD. Co-cultured MBECs displayed a significant increase in intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression in response to a short or prolonged exposure to OGD with 24 h of reperfusion. Neither OGD nor reperfusion had any effect on permeability of the MBEC monolayer. OGD induced a time-dependent increase in nuclear stabilisation of hypoxia inducible factor-1 alpha (HIF-1α) in glial cells which correlated to vascular endothelial growth factor (VEGF) secretion during OGD and subsequent reperfusion. Nuclear stabilisation of the nuclear factor kappa B (NFκB)p65 subunit by glial cells was dependent upon the duration of OGD. Reperfusion induced a significant increase in KC secretion by co-cultured glial cells after short exposure to OGD. Inflammatory activation of co-cultured MBECs and glia after 4 or 24 h OGD caused a significant increase in neutrophil transendothelial migration which correlated with MBEC expression of ICAM-1 and VCAM-1. A combination of these cell adhesion molecules with neutrophil integrins and soluble glial-derived mediators contributed to neutrophil transendothelial migration. These studies provide evidence that combined hypoxia and glucose withdrawal induces the activation of MBECs and glial cells in vitro. Cross-talk between these two cell types may further regulate their activation. As a result of this inflammatory activation, soluble MBEC and glial-derived mediators may contribute to neutrophil transendothelial migration through the regulation of MBEC cell adhesion molecule expression.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:553329 |
| Date | January 2012 |
| Creators | Leow-Dyke, Sophie |
| Contributors | Rothwell, Nancy |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.research.manchester.ac.uk/portal/en/theses/inflammatory-activation-of-the-cerebrovascular-endothelium-in-response-to-oxygenglucose-deprivation(32ef4859-9fa2-4dde-ab76-b547158ae045).html |
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