LC/MS/MS assessment of changes in placental angiotensin I metabolism in preeclampsia

Abstract

Background: Preeclampsia (PE) is a condition characterized by high blood pressure and significant proteinuria in pregnant women. It affects about 7% pregnancies and can be cause of fetal and maternal morbidity and mortality. During pregnancy, a physiological overexpression of the Renin-Angiotensin System (RAS) components is observed, including increased plasma Ang II level. Dysregulation of RAS in placenta may contribute to preeclampsia and uterine growth retardation. The aim of the study was to evaluate the Ang I metabolism in human preeclamptic placentas and to compare to normal pregnancies condition.

Method: Fragments of placental tissues were collected right after ceasarian section from PE and physiological pregnancies. Tissues were incubated in Krebs buffer in the presence of Ang I. Evaluation of Ang I metabolites in incubating fluid was performed by LC/MS/MS method. mRNA expression of main RAS components was measured by RT-PCR.

Results: Pattern of angiotensin metabolites did not differ between groups. The main products were Ang 1-7 and Ang II. Comparing to control group, more than 3-fold lower production of Ang II and Ang 1-7 in preeclampsia was observed. mRNA expressions of ACE and AT1 were significantly decreased in pre- eclamptic placentas, whereas higher expression of mRNA of ACE2 and MAS receptor were observed.

Conclusions: Production of Ang 1-7 by PE placentas was significantly lower than in control group. Significantly decreased mRNA expression of ACE and AT1 receptor and lower production of Ang II in placentas of PE patients suggest that placental Ang II/ACE/AT1r pathway could be less important than Ang 1-7/ACE-2/MASr pathway in development of preeclampsia, but this requires further investigations.

Keywords: RAS; angiotensin; angiotensinogen metabolism; placenta; preeclampsia.