Association of vascular endothelial growth factor and soluble fms-like tyrosine kinase-1 polymorphisms with their circulating protein levels in preeclampsia

Abstract

Introduction: Normal development of placental vascular tree requiring angiogenesis and vasculogenesis is structurally and functionally indispensable for both adequate placental growth and delivery of nutrients from mother to the fetus. Impaired placental angiogenesis has been implicated in the pathophysiology of pregnancy complications which have immediate and long-lasting effects on the mother and her child, such as preeclampsia (PE) and fetal growth restriction. The mechanisms underlying the deregulation of placental angiogenesis in PE include a misbalance between the secretion and activity of pro-angiogenic (vascular endothelial growth factor [VEGF]) and anti-angiogenic (soluble fms-like tyrosine kinase-1 [sFlt-1]) factors. Considering the important roles of VEGF and sflt1 in pregnancy, functional polymorphisms in these genes may be potentially important as genetic markers for susceptibility to PE. Thus, the aim of the study was to screen for the presence of VEGF and sFlt-1 gene polymorphisms and to measure their levels in PE patients and controls of Indian origin. Material and Methods: Fifty each of clinically diagnosed patients and gestational and maternal age-matched normotensive, nonproteinuric controls were recruited after taking informed consent. DNA isolated from blood samples was processed for polymerase chain reaction amplification followed by restriction fragment length polymorphism to screen for the presence of VEGF + 936C/T, sFlt-1 (+4244G/A, −4771G/T, −523C/G) polymorphisms. Serum levels of VEGF-A and sFlt-1 were measured by Sandwich enzyme-linked immunosorbent assay (ELISA). Results: Decreased frequency of wild type genotype with respect to VEGF + 936C/T and sFlt-1 (+4244G/A, −4771G/T, and −523C/G) polymorphisms was seen in patients. ELISA results showed lower VEGF-A (198.43 ± 14.63 pg/ml vs. 235.08 ± 16.72 pg/ml [mean ± standard error of mean]) and higher sFlt-1 levels (2932.81 [1802.33–5760.46] pg/ml vs. 1114.94 [655.03–2694.35] Median [Range]; P < 0.05) in patients as compared to controls. Preeclamptic women with increased frequency of VEGF + 936CT genotype had lower serum levels of VEGF-A. However, preeclamptic women with increased frequency of GA, AA, GT, TT, CG, and GG genotypes of sFlt-1 (+4244G/A, −4771G/T, −523C/G) polymorphisms had increased serum levels of sFlt-1. Discussion and Conclusion: The present study shows, for the first time, a possible association of VEGF and sFlt-1 polymorphisms with gene expression and altered protein levels in preeclamptic patients of Indian origin.