Molecular mechanisms of ovarian hyperstimulation syndrome: paracrine reduction of endothelial claudin 5 by hCG in vitro is associated with increased endothelial permeability.
BACKGROUND
Ovarian hyperstimulation syndrome (OHSS) is a potentially life-threatening complication of ovarian stimulation associated with severe vascular hyperpermeability. Primary co-cultures of human luteinized granulosa cells (LGCs) and human umbilical vein endothelial cells (HUVECs) were used as a model of steroidgenic/endothelial cell interaction in OHSS.


METHODS
hCG and the vascular endothelial growth factor (VEGF) inhibitor, Flt-1Fc, were added to co-cultures of LGCs and HUVECs separated by a micropore membrane. Endothelial permeability to labeled bovine serum albumin was measured and the expression of the endothelial cell-specific adhesion protein claudin 5 was investigated using immunocytochemistry and western blotting.


RESULTS
The addition of hCG increased HUVEC permeability in the presence of LGCs (P < 0.05). hCG increased VEGF concentrations in both chambers of the co-culture system (P < 0.05). The increased permeability in the presence of LGCs and hCG was inhibited when VEGF was blocked by Flt-1Fc (P < 0.05). Endothelial membrane claudin 5 protein was reduced in the presence of hCG and LGCs, as measured by immunocytochemistry (P < 0.05) and western blotting (P < 0.05) and this reduction was inhibited by Flt-1Fc. hCG had no direct effects on endothelial cell claudin 5.


CONCLUSIONS
For OHSS, this novel paradigm suggests that hCG can increase endothelial permeability by up-regulating VEGF in LGCs which causes reduction in endothelial claudin 5 expression.
Rodewald
M
M
Department of Obstetrics and Gynecology, University of Ulm, Prittwitzstrasse 43, 89075 Ulm, Germany.
Herr
D
D
Duncan
W C
WC
Fraser
H M
HM
Hack
G
G
Konrad
R
R
Gagsteiger
F
F
Kreienberg
R
R
Wulff
C
C
D002199:Capillary Permeability / Q000187:drug effects*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D062507:Claudin-5; D018920:Coculture Techniques; D015536:Down-Regulation; D004727:Endothelium / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D016471:Ovarian Hyperstimulation Syndrome / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors; D040281:Vascular Endothelial Growth Factor Receptor-1
C107466:CLDN5 protein, human; D006063:Chorionic Gonadotropin; D062507:Claudin-5; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D042461:Vascular Endothelial Growth Factor A; C501162:FLT1 protein, human; D040281:Vascular Endothelial Growth Factor Receptor-1