Angiotensin Converting Enzyme 90 kDa isoform: Biomarker for diagnosis of preeclampsia?

Abstract

Preeclampsia (PE), one of the leading gestational hypertensive diseases, is characterized by increased blood pressure (⩾140/90mmHg) and pathological proteinuria after 20weeks gestation. It is a complex, multifactorial syndrome with an unestablished etiology and cure. The search continues for a biomarker that could assist in the early prediction or diagnosis of PE, reducing the rate of maternal and fetal mortality. Based on the findings of Casarini et al. that suggest the 90kDa isoform of the Angiotensin Converting Enzyme (ACE) as a possible marker of hypertension, we hypothesized that this isoform may be present in pregnant women with PE, since they present a transient and spontaneous model of systemic arterial hypertension in pregnancy. We believe, therefore, that pregnant women with pure PE (PPE) express the ACE 90kDa isoform in urine, as well as having elevated isoform enzymatic activity, during pregnancy only. Postpartum, with the normalization of blood pressure, the protein isoform would no longer be expressed. Pregnant women with superimposed preeclampsia (SPE) would present the ACE 90kDa isoform both during and after the gestation period, and its enzymatic activity would remain high as they are chronically hypertensive. It is expected that normotensive pregnant women do not present this isoform in their urine as elevated blood pressure levels do not occur. Both normotensive and PPE affected pregnant women with a family history of hypertension, will possibly express the ACE 90kDa isoform before pregnancy and may become hypertensive, only after some years, through the influence of environmental factors and/or other diseases. If our hypothesis is confirmed, it will allow differentiation of PPE and SPE sooner than 12weeks postpartum, which is currently the estimated period for confirmation of the specific diagnosis. Furthermore, it could be an early biomarker for predicting the disease, enabling the physician to choose the best clinical management. In addition, it would minimize the use of other methods as the biological sample for obtaining the marker is urine, a practical and effective test with good reproducibility. Finally, test results would enable a greater understanding of the mechanisms involved in gestational hypertension.