Proteomic biomarker discovery for preeclampsia

Abstract

Preeclampsia is a serious multisystem complication of late pregnancy with adverse effects for mothers and babies. Currently this disorder is diagnosed from clinical observations occurring late in the disease process. Unknown factors in the maternal circulation, possibly released by the preeclamptic placenta, have been linked to the pathophysiological changes characteristic of the disorder. The research in this thesis used proteomic techniques to identify putative preeclampsia biomarkers from two sources: secreted from a placental cell line undergoing differentiation, and directly sampled from the serum and plasma of women with late-onset preeclampsia. The first part of this research examined the secreted proteome of a placental choriocarcinoma cell line (BeWo) undergoing forskolin-mediated differentiation. Development of serum-free culture techniques enabled analysis of these secreted proteins by two-dimensional gel electrophoresis (2DE). Statistical testing revealed the significant involvement of seven spots during this differentiation model, with VE-cadherin and matrix metalloproteinase 2 among the proteins identified. In the second part of this research, maternal serum and plasma proteins were compared from women with preeclampsia and healthy pregnant women. Serum samples were analyzed using 2DE, and plasma was subjected to difference gel electrophoresis (DIGE). Bioinformatic analysis of both datasets identified multiple spot clusters able to classify samples according to disease state. Five of these serum proteins were differentially regulated in preeclampsia, including two isoforms of apolipoprotein E whose isoform-specific expression was confirmed using western blots. Analysis of plasma from preeclamptic women identified six proteins, again including apolipoprotein E. Proteins from both studies are linked to preeclampsia pathophysiology through lipid transport, complement, and retinol transport systems. The culture methods and secreted proteomic techniques developed in this work have uncovered proteins in a placental cell line and maternal serum and plasma that are associated with preeclampsia. These methods can be extended to any system where secreted proteins are of interest. The differentially regulated proteins found in this study provide an important first step towards developing effective biomarkers for diagnosing and/or predicting preeclampsia.