Jiska Jebbink

Molecular genetics of preeclampsia and HELLP syndrome - A review

Preeclampsia is characterised by new onset hypertension and proteinuria and is a major obstetrical problem for both mother and foetus. Haemolysis elevated liver enzymes and low platelets (HELLP) syndrome is an obstetrical emergency and most cases occur in the presence of preeclampsia. Preeclampsia and HELLP are complicated syndromes with a wide variety in severity of clinical symptoms and gestational age at onset. The pathophysiology depends not only on periconceptional conditions and the foetal and placental genotype, but also on the capability of the maternal system to deal with pregnancy. Genetically, preeclampsia is a complex disorder and despite numerous efforts no clear mode of inheritance has been established. A minor fraction of HELLP cases is caused by foetal homozygous LCHAD deficiency, but for most cases the genetic background has not been elucidated yet. At least 178 genes have been described in relation to preeclampsia or HELLP syndrome. Confined placental mosaicism (CPM) is documented to cause early onset preeclampsia in some cases; the overall contribution of CPM to the occurrence of preeclampsia has not been adequately investigated yet. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.

Leukocyte activation and circulating leukocyte-derived microparticles in preeclampsia.

Problem  Preeclampsia shows characteristics of an inflammatory disease including leukocyte activation. Analyses of leukocyte‐derived microparticles (MP) and mRNA expression of inflammation‐related genes in leukocytes may establish which subgroups of leukocytes contribute to the development of preeclampsia.

Expression of Placental FLT1 Transcript Variants Relates to Both Gestational Hypertensive Disease and Fetal Growth

The recent discovery of additional alternative spliced FLT1 transcripts encoding novel soluble (s)FLT1 protein isoforms complicates both the predictive value and functional implications of sFLT1 in preeclampsia. We investigated FLT1 expression levels and splicing patterns in placentas of normotensive and preeclamptic women, and established the tissue specificity of all FLT1 transcript variants. mRNA levels of sFLT1 splice variants were determined by real-time polymerase chain reaction in 21 normal human tissues and placental biopsies from 91 normotensive and 55 preeclamptic women. Cellular localization of placental FLT1 expression was established by RNA in situ hybridization. Of all tissues investigated, placenta has by far the highest FLT1 mRNA expression level, mainly localized in the syncytiotrophoblast layer. More than 80% of placental transcripts correspond to sFLT1_v2. Compared with normotensive placenta, preeclamptic placenta has ≈3-fold higher expression of all FLT1 transcript variants (P<0.001), with a slight shift in favor of sFLT1_v1. Although to a lesser degree, transcript levels are also increased in placenta from normotensive women that deliver a small for gestational age neonate. We conclude that sFLT isoform–specific assays could potentially improve the accuracy of current sFLT1 assays for the prediction of preeclampsia. However, placental FLT1 transcript levels are increased not only in preeclampsia but also in normotensive pregnancy with a small for gestational age fetus. This may indicate a common pathway involved in the development of both conditions but complicates the use of circulating sFLT1 protein levels for the prediction or diagnosis of preeclampsia alone.

STOX1 is not imprinted and is not likely to be involved in preeclampsia

Previous studies showed that maternally inherited mutations in the STOX1 gene are responsible for pre-eclampsia. This is potentially of huge importance in the understanding of this disease. This study clearly showed that STOX1 is not imprinted and does not play such a role.

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.

Total bile acids in the maternal and fetal compartment in relation to placental ABCG2 expression in preeclamptic pregnancies complicated by HELLP syndrome

OBJECTIVE To investigate total bile acid (TBA) levels in maternal (MB) and umbilical cord blood (UCB) in normotensive, preeclamptic (PE), and PE pregnancies complicated by hemolysis elevated liver enzymes and low platelets (HELLP) syndrome in the context of ABCG2 placental gene expression levels, a recently reported placental bile acid transporter. METHODS TBA levels were determined in 83 paired MB and UCB samples of normotensive, PE and PE/HELLP pregnancies and in 22 paired arterial and venous UCB samples from uncomplicated term pregnancies. ABCG2 gene expression was measured in 104 human placentas by reverse transcriptase quantitative polymerase chain reaction. RESULTS Overall, TBA levels in MB are higher compared to levels in UCB (p<0.0001), but this comparison looses statistical significance for the 11 PE/HELLP cases. TBA levels in maternal blood are increased in PE/HELLP compared to PE pregnancies (p=0.016). TBA levels in arterial and venous UCB from 22 normotensive pregnancies are not statistically different. ABCG2 expression is reduced in pregnancies where preeclampsia is further complicated by HELLP syndrome. ABCG2 expression in human placenta is not correlated with TBA levels in either the maternal or fetal compartment. CONCLUSION Increased maternal TBA levels in PE/HELLP pregnancies indicate a relation between bile acids in the maternal circulation and HELLP syndrome. As overall TBA levels in maternal blood are increased compared to UCB, we conclude that the placenta partly protects the fetus from increased maternal TBA levels. This consistent difference in TBA levels between the maternal and fetal compartment is unrelated to the placental expression of ABCG2.

Intussusception during pregnancy after laparoscopic Roux-en-Y gastric bypass

In fertile women, the laparoscopic Roux-en-Y gastric bypass (LRYGB) is being increasingly performed. Pregnancy and LRYGB both give an increased risk of intussusception, which can lead to bowel necrosis, sepsis and preterm labour. We describe two pregnant women with a history of LRYGB who presented to the emergency department with non-specific abdominal pain. Both were diagnosed with intussusception. These cases illustrate that intussusception should be considered in pregnant women with a history of LRYGB who present with non-specific abdominal pain. Only MRI, CT scan or diagnostic laparoscopy is sufficient for diagnosis. Early diagnosis may prevent serious complications.

HELLP syndrome preceded by intrahepatic cholestasis of pregnancy: one serious itch

We present four women with seven ongoing pregnancies. Five pregnancies were complicated by intrahepatic cholestasis of pregnancy (ICP) and severe haemolysis, elevated liver enzymes and low platelets (HELLP) syndrome with uncommon maternal morbidity. The combination of ICP and HELLP syndrome has not previously been reported. Awareness is warranted to accurately identify this combination of pregnancy-specific diseases with severe maternal morbidity.

ORIGINAL ARTICLE: Leukocyte Activation and Circulating Leukocyte-Derived Microparticles in Preeclampsia

Problem  Preeclampsia shows characteristics of an inflammatory disease including leukocyte activation. Analyses of leukocyte‐derived microparticles (MP) and mRNA expression of inflammation‐related genes in leukocytes may establish which subgroups of leukocytes contribute to the development of preeclampsia.

ORIGINAL ARTICLE: Leukocyte Activation and Circulating Leukocyte-Derived Microparticles in Preeclampsia: LEUKOCYTE ACTIVATION AND MICROPARTICLES IN PREECLAMPSIA

Problem  Preeclampsia shows characteristics of an inflammatory disease including leukocyte activation. Analyses of leukocyte‐derived microparticles (MP) and mRNA expression of inflammation‐related genes in leukocytes may establish which subgroups of leukocytes contribute to the development of preeclampsia.