Pregnancy-associated and placental proteins in the placental tissue of normal pregnant women and patients with pre-eclampsia at term

Abstract

Objective: Pre-eclampsia is a placental disease of unknown cause. Maternal circulating concentrations of a number of protein markers are altered (mainly increased) in pre-eclampsia in comparison with controls of matched gestational age. Inhibin A and activin A were found to be elevated even before the onset of the disease. The aim of this study was to compare the levels of inhibin A, activin A: follistatin ratio, leptin, pregnancy-associated plasma protein-A (PAPP-A), human placental lactogen (HPL), placenta growth factor (PLGF) and pregnancy-specific β1-glycoprotein (SP1) in placental extracts of normal pregnant women and pre-eclampsia patients at term. Methods: Placental tissue from normal pregnancies (n = 14) and patients with pre-eclampsia (n = 13) were collected at term (≥ 37 weeks of gestation) and stored at -80°C. The frozen tissue pieces were homogenised and the above-mentioned proteins were measured by specific enzyme-linked immunosorbent assays. Results: Placental contents of inhibin A and PAPP-A were significantly higher (P < 0.05) in pre-eclampsia placental extracts compared with the controls. Activin A:follistatin ratio was higher (23) in pre-eclampsia extracts than in the controls (15). Leptin, PLGF, SP1 and HPL levels were not altered in the term pre-eclampsia placenta. Inhibin A and PAPP-A contents were increased in the placental extracts of pre-eclampsia patients. Conclusion: Our data suggest that the placenta, possibly by a compensatory mechanism, is at least in part responsible for the altered serum levels observed in pre-eclampsia.