Potentiating effect of endothelial cells on astrocytic plasminogen activator inhibitor type-1 gene expression in an in vitro model of the blood-brain barrier.
There is accumulating evidence of the importance of cellular communication between the cells that compose the blood-brain barrier (BBB). Astrocytes are known to affect the expression of tissue-type plasminogen activator (t-PA) and its inhibitor plasminogen activator inhibitor type-1 (PAI-1) in endothelial cells. We investigated the influence of endothelial cells on astrocytic gene expression of PAI-1, protease nexin-1 (PN-1) and t-PA using an in vitro model of the BBB. Primary rat astrocyte-enriched cultures were cocultured with primary adult rat brain microvascular endothelial cells on opposite sides of a transwell membrane. After coculturing for 9-11 days, the cultures were treated with lipopolysaccharide (LPS) for 8 h or 24 h. The levels of PAI-1, PN-1 and t-PA mRNA in untreated and treated monocultures and cocultures were analyzed by Real-Time RT-PCR. Cocultivation of astrocytes and endothelial cells increased astrocytic PAI-1 mRNA expression, and this response was further amplified by LPS treatment. The levels of PN-1 and t-PA mRNA expression in astrocytes were unaffected by cocultivation and/or LPS treatment. Analysis of endothelial PAI-1 and t-PA gene expression revealed increased PAI-1 mRNA levels in cocultured cells, whereas t-PA mRNA levels remained unchanged. These results demonstrate that the cocultivation of astrocytes and endothelial cells induces a pronounced increase in astrocytic PAI-1 gene expression, and that this effect is amplified by LPS treatment. These findings imply an important role for intercellular crosstalk in modulating PAI-1 gene expression within the BBB, under both physiologic and pathophysiologic conditions.
Hultman
K
K
Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden. karin.hultman@neuro.gu.se
Björklund
U
U
Hansson
E
E
Jern
C
C
D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism*; D001812:Blood-Brain Barrier / Q000378:metabolism*; D001921:Brain / Q000166:cytology / Q000378:metabolism; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D015870:Gene Expression; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D058258:Serpin E2; D015843:Serpins / Q000235:genetics / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000235:genetics / Q000378:metabolism
D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D058258:Serpin E2; C541127:Serpine2 protein, rat; D015843:Serpins; D010959:Tissue Plasminogen Activator