Plasma markers of angiogenesis in pregnancy induced hypertension

Abstract

This study tests the hypothesis that abnormalities in plasma indices of angiogenesis, such as Vascular Endothelial Growth Factor (VEGF) and angiopoietins (Ang-1, Ang-2), as well as their soluble receptors Flt-1 (sFlt-1) and Tie 2 (sTie-2) respectively, are present in women with in pregnancy-induced hypertension (PIH). We also measured platelet levels of VEGF and Ang-1 (pVEGF and pAng-1 respectively). We studied 69 consecutive women with PIH (34 without proteinuria, and 35 with proteinuria, i.e. preeclampsia) who were compared to 64 consecutive women with normotensive pregnancies and 30 normotensive non-pregnant women, in a cross-sectional study. Using ELISA, we measured levels of plasma VEGF, Ang-1 & 2, Tie-2 and sFlt-1, and also the levels of angiogenic markers within the platelet [platelet VEGF (pVEGF) and platelet Ang-1 (pAng1)] by lysing a fixed number of platelets with 0.5% tween. Results show that levels of plasma VEGF, Ang-1, Ang2, sFlt-1 and Tie-2 were significantly different between the study groups. Post hoc analyses revealed plasma Ang-1 was highest in the preeclampsia group (p<0.001), whilst Ang-2 was highest in the normotensive pregnant group (p-=0.018). Plasma Tie-2 was highest in the PIH group. VEGF levels were significantly different between the preeclampsia group and the PIH group (p<0.05). Platelet VEGF levels were higher in the non-pregnant group than in the pregnant group, but there were no significant differences in the platelet levels of Ang-1 between the different groups. Ang-2, sFlt-1 and Tie-2 were undetectable in the platelet lysate in any of the patient groups or controls. Blood pressure was a major determinant of the different angiogenic factors studied. Abnormal indices of angiogenesis are evident in PIH and preeclampsia, with higher levels of sFlt-1 and lower levels of VEGF; in PIH, increased levels of Ang-1 and Tie-2, but reduced Ang-2, are evident compared to normal pregnancy. These abnormalities may have implications for the pathogenesis of PIH and preeclampsia.