Endothelial cell-astrocyte interactions and TGF beta are required for induction of blood-neural barrier properties.
We sought to establish a blood-neural barrier (BNB) model of astrocyte contact with endothelial cells (EC) to test the hypothesis that transforming growth factor beta (TGF beta) promotes an EC barrier-phenotype. Astrocyte-EC contact induced BNB properties in EC. Transendothelial resistance was augmented by direct contact between astrocytes-EC, but not by astrocyte-conditioned medium or astrocyte-EC coculture conditioned medium. Coculture of EC and astrocytes led to significant increase in endothelial occludin levels and junctional localization. EC gamma-glutamyl-transferase (GGT) activity was increased by direct contact with astrocytes, by conditioned medium from cocultures or by TGF beta1. Coculture inhibited EC proliferation with no effect on astrocyte proliferation. A neutralizing antibody to TGF beta decreased GGT activity in cocultures and increased cell number. Whereas total TGF beta was not significantly altered by coculture, activated TGF beta increased in astrocyte-EC cocultures. In summary, astrocyte-EC contact induces BNB characteristics in EC and locally activated TGF beta is responsible for part of the induction.
Biological and Biomedical Sciences Graduate Program, Harvard Medical School, Boston, MA, USA.
Claudia M
CM
Garcia
Diane C
DC
Darland
Lauren J
LJ
Massingham
Patricia A
PA
D'Amore
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000378:metabolism*; D015153:Blotting, Western; D002450:Cell Communication / Q000502:physiology*; D002455:Cell Division; D002478:Cells, Cultured; D018920:Coculture Techniques; D017097:Electric Impedance; D042783:Endothelial Cells / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D062793:Occludin; D019108:Tight Junctions / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D008565:Membrane Proteins; D062793:Occludin; D016212:Transforming Growth Factor beta; D005723:gamma-Glutamyltransferase