Endothelial cell–astrocyte interactions and TGFβ are required for induction of blood–neural barrier properties

• Published in: Brain research. Developmental brain research Vol. 152; no. 1; pp. 25 - 38
• Main Authors: Garcia, Claudia M, Darland, Diane C, Massingham, Lauren J, D'Amore, Patricia A
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 18.08.2004
• Subjects: Animals; Astrocytes - metabolism; Blood-Brain Barrier - metabolism; Blood–retinal barrier; Blotting, Western; Cell Communication - physiology; Cell Division; Cells, Cultured; Cell–cell interaction; Coculture Techniques; Electric Impedance; Electrical resistance; Endothelial Cells - metabolism; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; Gamma glutamyl transferase; gamma-Glutamyltransferase - metabolism; Immunohistochemistry; Membrane Proteins - metabolism; Microscopy, Confocal; Occludin; Retinal vasculature; Tight junction; Tight Junctions - metabolism; Transforming Growth Factor beta - metabolism; Retinal vasculature; Electrical resistance; Cellular and molecular biology; Tight junction; Gamma glutamyl transferase; Blood–retinal barrier; Cell–cell interaction
• ISSN: 0165-3806
• DOI: 10.1016/j.devbrainres.2004.05.008

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 β (TGFβ) 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 γ-glutamyl-transferase (GGT) activity was increased by direct contact with astrocytes, by conditioned medium from cocultures or by TGFβ1. Coculture inhibited EC proliferation with no effect on astrocyte proliferation. A neutralizing antibody to TGFβ decreased GGT activity in cocultures and increased cell number. Whereas total TGFβ was not significantly altered by coculture, activated TGFβ increased in astrocyte–EC cocultures. In summary, astrocyte–EC contact induces BNB characteristics in EC and locally activated TGFβ is responsible for part of the induction.