C. Ris-Stalpers

Accuracy of circulating placental growth factor, vascular endothelial growth factor, soluble fms‐like tyrosine kinase 1 and soluble endoglin in the prediction of pre‐eclampsia: a systematic review and meta‐analysis

Please cite this paper as: Kleinrouweler C, Wiegerinck M, Ris‐Stalpers C, Bossuyt P, van der Post J, von Dadelszen P, Mol B, Pajkrt E, for the EBM CONNECT Collaboration. Accuracy of circulating placental growth factor, vascular endothelial growth factor, soluble fms‐like tyrosine kinase 1 and soluble endoglin in the prediction of pre‐eclampsia: a systematic review and meta‐analysis. BJOG 2012;119:778–787.

Hydrogen sulfide producing enzymes in pregnancy and preeclampsia

Preeclampsia, a human pregnancy specific disorder is characterized by an anti-angiogenic state. As hydrogen sulfide (H(2)S) has pro-angiogenic and anti-oxidative characteristics, we hypothesized that H(2)S levels could play a role in the pathogenesis of preeclampsia and studied the placental expression of the H(2)S-producing enzymes cystathionine-γ-lyase (CSE) and cystathionine-β-synthase (CBS). CBS and CSE protein are expressed in the fetal-placental endothelium and CBS only in Hofbauer cells. CBS mRNA expression is decreased (p = 0.002) in early-onset preeclampsia, while CSE mRNA is unchanged. Thus, down regulation of CBS during early-onset preeclampsia may result in less H(2)S-production and may aid in the anti-angiogenic state.

Increased glucocerebrosidase expression and activity in preeclamptic placenta

INTRODUCTION Lysosomal glucosidase beta acid (GBA) deficiency is inherent to Gaucher disease, Parkinsonism and Lewy-body dementia. Increased GBA expression has never been associated with human disease. We describe increased GBA expression and activity in placenta from preeclamptic pregnancies. METHODS 112 placenta biopsies were available for qPCR, analysis of GBA gene expression and activity. Microanalysis was performed on 20 placenta samples. Alternatively spliced placental GBA transcripts were cloned, expressed in HEK293 cells and analyzed by Western blot and activity assay. RESULTS GBA is expressed in the syncytiotrophoblast layer of human placenta already at 5 weeks of gestation. We identified five novel GBA transcripts in placenta that enzymatically inactive when expressed in HEK293 cells. Both GBA RNA expression and enzymatic activity are upregulated in preeclamptic placenta. Microarray analysis of 20 placenta tissues identified 158 genes co-regulating with GBA expression and gene enrichment analysis highlights lysosomal function. In our micro-array data GBA expression does not correlate with FLT1 expression, currently the most powerful marker for preeclampsia. There are 89 transcripts that are negatively correlated with GBA expression of which BMP4 and TFEB are interesting as they are essential to early placenta function. DISCUSSION Although very speculative, we hypothesize that increased GBA expression might relate to placentation through decreased BMP4 signaling or vascularization through downregulation of TFEB. Ceramide, the product of hydrolysis of glucosylceramide by GBA and involved in the regulation of cell differentiation, survival and apoptosis, is another putative candidate linking increased GBA activity to preeclampsia. Both pathways merit further investigation.

Placental expression of heparan sulfate 3-O-sulfotransferase-3A1 in normotensive and pre-eclamptic pregnancies.

INTRODUCTION The endothelial glycocalyx, consisting of membrane-bound proteoglycans and attached glycosaminoglycans plays an important role in vascular homeostasis. We aimed to assess whether glycocalyx mRNA transcripts are differentially expressed in placental tissue of pre-eclamptic and normotensive women. METHODS We evaluated the expression of transcripts encoding for proteins involved in glycocalyx synthesis and degradation using a microarray analysis of placental mRNA obtained from pre-eclamptic and normotensive women. Participants were recruited from the department of obstetrics at a university hospital in Amsterdam, The Netherlands. The most prominent differentially expressed transcript was validated by qPCR on 112 additional placenta samples. RESULTS Of 78 preselected genes involved in glycocalyx synthesis and degradation, only HS3ST3A1 mRNA was differentially expressed in placental tissue obtained from pre-eclamptic women (N = 12) compared to normotensive women (N = 12, fold change = 0.61, p = 0.02). Validation with qPCR in additional placental samples of 64 normotensive and 48 pre-eclamptic women confirmed that normalized mRNA expression of HS3ST3A1 was decreased by 27% (95% CI 14%-41%) in placental tissue obtained from pre-eclamptic compared to normotensive women (p < 0.001). HS3ST3A1 expression was positively correlated with neonatal birth weight in normotensive women (r = 0.35, p < 0.01) and inversely correlated with mean arterial pressure of women with pre-eclampsia (r = 0.32, p = 0.02). CONCLUSIONS The mRNA expression of HS3ST3A1, which encodes for a 3-O sulfating enzyme of heparan sulfate (3-OST-3A1), is decreased in pre-eclamptic placental tissue. Expression of this glycocalyx synthesis transcript is correlated with maternal blood pressure and neonatal birth weight, suggesting a possible role in pre-eclampsia-associated placental dysfunction.

Higher decidual EBI3 and HLA-G mRNA expression in preeclampsia: Cause or consequence of preeclampsia

The maternal immune system must adapt to tolerate the invasion of the allogeneic feto-placental unit. It is generally accepted that improper adaptation causes pregnancy complications like preeclampsia. The Epstein-Barr virus-induced gene 3 (EBI3) protein is a subunit of immune-modulatory cytokines interleukin 27 (IL-27) and IL-35. EBI3 has been reported to associate with HLA-G. In this small pilot study we find higher decidual EBI3 (p<0.05) and HLA-G (p<0.01) mRNA expression in preeclampsia (n=7) compared to normotensive (n=8) pregnancies. Whether the higher EBI3 and HLA-G mRNA expression is a consequence or cause of preeclampsia remains to be answered. Further research to determine the effects on IL-27 and IL-35 is needed.

Maternal circulating PlGF concentrations and placenta-related pregnancy complications: First results from the CoLab AngF Study

INTRODUCTION Circulating angiogenic factors are potential markers for preeclampsia, but heterogeneous studies have failed to identify precise predictive/diagnostic properties. The Global CoLaboratory is investigating how to merge published data of angiogenic factors for meta-analysis on an individual sample basis. OBJECTIVE To amalgamate pregnancy angiogenic factor studies, investigate diagnostic and predictive properties of these markers in preeclampsia and placenta-related pregnancy complications, and to test if measures from disparate platforms can be standardised. This is the first report using PlGF measures to diagnose preeclampsia. METHODS Data were derived from 15 cohorts, within and outside the CoLaboratory network. Women were classified as either case (confirmed diagnosis of preeclampsia at sampling) or non-case (no preeclampsia at sampling). Individual PlGF measurements from four different analytical platforms were used, along with transformations of the data (e.g. log-transformations, transformations to a baseline platform). Transformed measurements were standardised both for specific platforms and globally, stratifying on gestational age. Different statistical techniques were compared. RESULTS The database currently contains 1442 cases and 11,512 non-cases, which were used to define an algorithm to merge PlGF measurements from different platforms. Non-case distributions were used to standardise case results. Diagnostic PlGF measurements in relation to preeclampsia will be presented and confirm feasibility. CONCLUSIONS Future studies can extend this approach to other angiogenic factors, prediction as well as diagnosis and to other placenta-related disorders.