Failure to up-regulate VEGF165b in maternal plasma is a first trimester predictive marker for pre-eclampsia

Abstract

Pre-eclampsia is a pregnancy-related condition characterized by hypertension, proteinuria and endothelial dysfunction. VEGF165b, formed by alternative splicing of VEGF (vascular endothelial growth factor) pre-mRNA, inhibits VEGF165-mediated vasodilation and angiogenesis, but has not been quantified in pregnancy. ELISAs were used to measure means±S.E.M. plasma VEGF165b, sEng (soluble endoglin) and sFlt-1 (soluble fms-like tyrosine kinase-1). At 12 weeks of gestation, the plasma VEGF165b concentration was significantly up-regulated in plasma from women who maintained normal blood pressure throughout their pregnancy (normotensive group, 4.90±1.6 ng/ml; P<0.01, as determined using a Mann-Whitney U test) compared with non-pregnant women (0.40±0.22 ng/ml). In contrast, in patients who later developed pre-eclampsia, VEGF165b levels were lower than in the normotensive group (0.467±0.209 ng/ml), but were no greater than non-pregnant women. At term, plasma VEGF165b concentrations were greater than normal in both pre-eclamptic (3.75±2.24 ng/ml) and normotensive (10.58 ng/ml±3.74 ng/ml; P>0.1 compared with pre-eclampsia) pregnancies. Patients with a lower than median plasma VEGF165b at 12 weeks had elevated sFlt-1 and sEng pre-delivery. Concentrations of sFlt-1 (1.20±0.07 and 1.27±0.18 ng/ml) and sEng (4.4±0.18 and 4.1±0.5 ng/ml) were similar at 12 weeks of gestation in the normotensive and pre-eclamptic groups respectively. Plasma VEGF165b levels were elevated in pregnancy, but this increase is delayed in women that subsequently develop pre-eclampsia. In conclusion, low VEGF165b may therefore be a clinically useful first trimester plasma marker for increased risk of pre-eclampsia.