Responses of endothelial cell and astrocyte matrix-integrin receptors to ischemia mimic those observed in the neurovascular unit.
OBJECTIVE
Apposition of endothelial cells and astrocyte foot processes to the basal lamina matrix is postulated to underlie the cerebral microvessel permeability barrier. Focal cerebral ischemia induces rapid loss of select matrix-binding integrins from both cell compartments in the nonhuman primate. This study is the first to examine the conditions underlying integrin loss from these cell-types during ischemia in vitro and their relation to the changes in vivo.


METHODS
The impact of normoxia or standardized oxygen-glucose deprivation on integrin expression by murine primary cerebral endothelial cells and astrocytes grown on matrix substrates (collagen IV, laminin, and perlecan) of the basal lamina were quantitatively assessed by flow cytometry.


RESULTS
Endothelial cell expression of the beta1 and alpha 5 subunits significantly increased on all matrix ligands, whereas astrocytes displayed modest significant decreases in alpha 5 and alpha 6 subunits. Oxygen-glucose deprivation produced a further significant increase in subunit beta1 expression by both cell types, but a clear decrease in both alpha1 and alpha 6 subunits by murine astrocytes.


CONCLUSIONS
Ischemia in vitro significantly increased endothelial cell beta1 expression, which is consistent with the increase in beta1 transcription by microvessels peripheral to the ischemic core. The loss of alpha1 and alpha 6 integrins from murine astrocytes is identical to that seen in the nonhuman primate in vivo. These findings establish both isolated murine cerebral endothelial cells and astrocytes as potential integrin response cognates of microvascular cells of the neurovascular unit in primates, and allow determination of the mechanisms of their changes to ischemia.
Milner
Richard
R
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA.
Hung
Stephanie
S
Wang
Xiaoyun
X
Berg
Greta I
GI
Spatz
Maria
M
del Zoppo
Gregory J
GJ
D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D002545:Brain Ischemia / Q000378:metabolism*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D039423:Integrin alpha1 / Q000378:metabolism; D039482:Integrin alpha5 / Q000378:metabolism; D039503:Integrin alpha6 / Q000378:metabolism; D019012:Integrin beta1 / Q000378:metabolism; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D010100:Oxygen / Q000378:metabolism
D016326:Extracellular Matrix Proteins; D039423:Integrin alpha1; D039482:Integrin alpha5; D039503:Integrin alpha6; D019012:Integrin beta1; D016023:Integrins; D005947:Glucose; D010100:Oxygen