Preeclampsia and Increased Permeability Over the Blood–Brain Barrier : A Role of Vascular Endothelial Growth Receptor 2

BACKGROUND: Cerebral complications in preeclampsia are leading causes of maternal mortality worldwide but the underlying pathophysiology is largely unknown and a challenge to study. Using an in vitro model of the human blood brain barrier (BBB), we explored the role of vascular endothelial growth factor receptor 2 (VEGFR2) in preeclampsia. METHODS: The human brain endothelial cell line (hCMEC/D3) cultured on Tranwells insert were exposed (12 h) to plasma from women with preeclampsia (n=28), normal pregnancy (n=28) and non-pregnant (n=16) controls. Transendothelial electrical resistance (TEER) and permeability to 70 kDa FITC-dextran were measured for assessment of BBB integrity. We explored possible underlying mechanisms, with focus on expression of tight junction proteins and phosphorylation of two tyrosine residues of VEGFR2, associated with vascular permeability and migration (pY951) and cell proliferation (pY1175). Plasma concentrations of soluble FMS like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) were measured in order to establish correlations with in vitro results. RESULTS: hCMEC/D3 exposed to plasma from women with preeclampsia exhibited reduced TEER and increased permeability to 70 kDa FITC-dextran. Further, these cells up-regulated the mRNA levels of VEGFR2, as well as pY951-VEGFR2; but reduced pY1175-VEGFR2 (p&0.05 in all cases). No difference in mRNA expression of tight junction protein was observed between gruops. There was no correlation between angiogenic biomarkers and BBB permeability. CONCLUSION: We present a promising in vitro model of the BBB in preeclampsia. Selective tyrosine phosphorylation of VEGFR2 may participate in the increased BBB permeability in preeclampsia irrespective of plasma concentrations of angiogenic biomarkers.