title: Tissue plasminogen activator expression and barrier properties of human brain microvascular endothelial cells.
abstract: BACKGROUND
  Tissue plasminogen activator (tPA) regulates fibrinolysis and is routinely used as ischemic stroke pharmacotherapy. We hypothesized that brain microvascular tPA expression and barrier properties of endothelial cells are substantially related.
  
  
  METHODS
  Human brain microvascular endothelial cells were incubated with two agents known to modify cAMP pathways: forskolin and rolipram. We analyzed development of endothelial barrier properties, i.e., trans-endothelial electrical resistance (TEER), permeability of endothelial cell monolayer, expression of influx transporter glut-1 and endothelial tight junction molecules occludin and claudin-5, tPA antigen release, and levels of endothelial tPA mRNA.
  
  
  RESULTS
  Forskolin plus rolipram-treated endothelial cells showed increased TEER compared to controls (174±20% of control at day six, p<0.01), while permeability to albumin and 70kDa dextran was reduced (21±6.8% of control and 3.8±0.3% of control, respectively, p<0.001). In addition, occludin and claudin-5 protein were up-regulated, occludin mRNA was increased to 206±60% of control (p<0.05), glut-1 mRNA was increased to 196±68% of control (p<0.05), levels of tPA protein were reduced to 35±7.0% of control (p<0.001) after six days, and tPA mRNA was reduced to 32±7.7% of control (p<0.01). TPA and occludin mRNA levels were inversely associated (r=-0.68, p<0.05).
  
  
  CONCLUSIONS
  In this in vitro model, barrier properties were strongly linked (by inverse association) with tPA expression of brain microvascular endothelial cells.
authors.affiliation: Departments of Neurology, University of California-Irvine, 101 The City Drive South, Orange, CA 92868, USA.
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.forename: Shuo
authors.initials: S
authors.lastname: Liu
authors.forename: Shur-Jen
authors.initials: SJ
authors.lastname: Wang
authors.forename: Chuanhui
authors.initials: C
authors.lastname: Yu
authors.forename: Annlia
authors.initials: A
authors.lastname: Paganini-Hill
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Fisher
mesh_terms: D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D062507:Claudin-5; D057167:Claudins / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D051272:Glucose Transporter Type 1 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D062793:Occludin; D012333:RNA, Messenger / Q000378:metabolism; D020889:Rolipram / Q000494:pharmacology; D019108:Tight Junctions / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000235:genetics / Q000378:metabolism*
chemical_list: C107466:CLDN5 protein, human; D062507:Claudin-5; D057167:Claudins; D004791:Enzyme Inhibitors; D051272:Glucose Transporter Type 1; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D012333:RNA, Messenger; D005576:Colforsin; D010959:Tissue Plasminogen Activator; D020889:Rolipram