Integrated Placental Modelling of Histology with Gene Expression to Identify Functional Impact on Fetal Growth

Fetal growth restriction (FGR) is a leading cause of perinatal morbidity and mortality. Altered placental formation and functional capacity are major contributors to FGR pathogenesis. Relating placental structure to function across the placenta in healthy and FGR pregnancies remains largely unexplored but could improve understanding of placental diseases. We investigated integration of these parameters spatially in the term human placenta using predictive modelling. Systematic sampling was able to overcome heterogeneity in placental morphological and molecular features. Defects in villous development, elevated fibrosis, and reduced expression of growth and functional marker genes (IGF2, VEGA, SLC38A1, and SLC2A3) were seen in age-matched term FGR versus healthy control placentas. Characteristic histopathological changes with specific accompanying molecular signatures could be integrated through computational modelling to predict if the placenta came from a healthy or FGR pregnancy. Our findings yield new insights into the spatial relationship between placental structure and function and the etiology of FGR

Characterisation of maternal pre-eclampsia susceptibility genes

© 2015 Dr. Ee Juen Hannah YongIntroduction: Pre-eclampsia (PE) has affected pregnant women throughout human history and remains a leading cause of maternal and fetal mortality and morbidity worldwide today. PE is clinically characterised by de novo hypertension and proteinuria developing after 20 weeks’ gestation that resolves with delivery of the fetus and placenta. Up to 8% of all pregnant women are afflicted with the disorder, which may necessitate premature delivery of the fetus in severe cases. The aetiology of the disorder remains unknown, although the placenta is widely accepted to be central to the pathogenesis of PE, as PE can occur in women with molar pregnancies, where there is no viable fetus. A family history of PE is a major risk factor, with heritability estimates of up to 54%. Genetic linkage and association studies in the Australian/New Zealand population previously identified susceptibility loci on chromosomes 2, 5 and 13 for PE. Bioinformatic analyses of these loci yielded the following candidate maternal PE susceptibility genes from various functional groups: ACVR1, ACVR1C, ACVR2A, INHA and INHBB from the activin/inhibin signalling group; ERAP1, ERAP2 and LNPEP from the M1 aminopeptidase family; and COL4A1 and COL4A2 from the connective tissue components group. The main aim of this thesis was to characterise the expression and determine the functional significance of these genes in the development of PE. Main findings: The bulk of the findings of this thesis has been published or is accepted for publication in multiple international peer-reviewed journals. The first Placenta paper in Chapter 3, demonstrated significantly increased mRNA expression of the candidate genes – ACVR1, INHBB, ERAP1, ERAP2, LNPEP, COL4A1 and COL4A2, in the pre-eclamptic maternal decidual tissue, which correlated with greater clinical severity of PE. The second Placenta paper in Chapter 4, examined the levels of arresten and canstatin fragments, which are derived from the COL4A1 and COL4A2 genes respectively, in the plasma from pre-eclamptic women and gestational age matched normotensive controls. Arresten levels were significantly increased as early as 16 weeks’ gestation in pre-eclamptic plasma. The subsequent two results chapters examined the functional roles of the activin A receptor, ACVR2A, in decidual stromal cells and endothelial cells. In Chapter 5, modelling the decreased expression observed in pre-eclamptic decidua, using an in vitro cell culture model, showed that decidual stromal cells had an impaired ability to decidualise and caused abnormal regulation of multiple extravillous trophoblast functions. Chapter 6, which forms the basis of the Pregnancy Hypertension paper, revealed that the higher baseline concentrations of activin A observed in PE resulted in vascular endothelial dysfunction, which was further exacerbated by a reduction in ACVR2A expression. Finally in Chapter 7, which was published in PLoS One, shared biological pathways of the susceptibility genes from the different functional group were identified through bioinformatics analyses. These shared pathways provide an insight as to the cumulative contribution of the different genes in the development of PE. Conclusions: The overall findings of the thesis provide evidence to support a causative, functional role of these maternal susceptibility genes in the pathogenesis of PE. The altered expression of genes, which are detectable before the onset of clinical disease, suggests the potential for the development of novel predictive biomarkers. Given how a single gene can affect the functions of multiple cell types present at the maternal-fetal interface, it is likely that the multiple gene alterations would have cumulative functional effects that ultimately influence the onset and severity of PE

Epithelial-mesenchymal transition during extravillous trophoblast differentiation

A successful pregnancy depends on the intricate and timely interactions of maternal and fetal cells. Placental extravillous cytotrophoblast invasion involves a cellular transition from an epithelial to mesenchymal phenotype. Villous cytotrophoblasts undergo a partial epithelial to mesenchymal transition (EMT) when differentiating into extravillous cytotrophoblasts and gain the capacity to migrate and invade. This review summarizes our current knowledge regarding known regulators of EMT in the human placenta, including the inducers of EMT, upstream transcription factors that control EMT and the downstream effectors, cell adhesion molecules and their differential expression and functions in pregnancy pathologies, preeclampsia (PE) and fetal growth restriction (FGR). The review also describes the research strategies that were used for the identification of the functional role of EMT targets in vitro. A better understanding of molecular pathways driven by placental EMT and further elucidation of signaling pathways underlying the developmental programs may offer novel strategies of targeted therapy for improving feto-placental growth in placental pathologies including PE and FGR

Integrated Placental Modelling of Histology with Gene Expression to Identify Functional Impact on Fetal Growth

Fetal growth restriction (FGR) is a leading cause of perinatal morbidity and mortality. Altered placental formation and functional capacity are major contributors to FGR pathogenesis. Relating placental structure to function across the placenta in healthy and FGR pregnancies remains largely unexplored but could improve understanding of placental diseases. We investigated integration of these parameters spatially in the term human placenta using predictive modelling. Systematic sampling was able to overcome heterogeneity in placental morphological and molecular features. Defects in villous development, elevated fibrosis, and reduced expression of growth and functional marker genes (IGF2, VEGA, SLC38A1, and SLC2A3) were seen in age-matched term FGR versus healthy control placentas. Characteristic histopathological changes with specific accompanying molecular signatures could be integrated through computational modelling to predict if the placenta came from a healthy or FGR pregnancy. Our findings yield new insights into the spatial relationship between placental structure and function and the etiology of FGR

Integrated Placental Modelling of Histology with Gene Expression to Identify Functional Impact on Fetal Growth.

Fetal growth restriction (FGR) is a leading cause of perinatal morbidity and mortality. Altered placental formation and functional capacity are major contributors to FGR pathogenesis. Relating placental structure to function across the placenta in healthy and FGR pregnancies remains largely unexplored but could improve understanding of placental diseases. We investigated integration of these parameters spatially in the term human placenta using predictive modelling. Systematic sampling was able to overcome heterogeneity in placental morphological and molecular features. Defects in villous development, elevated fibrosis, and reduced expression of growth and functional marker genes (IGF2, VEGA, SLC38A1, and SLC2A3) were seen in age-matched term FGR versus healthy control placentas. Characteristic histopathological changes with specific accompanying molecular signatures could be integrated through computational modelling to predict if the placenta came from a healthy or FGR pregnancy. Our findings yield new insights into the spatial relationship between placental structure and function and the etiology of FGR

Integrated Placental Modelling of Histology with Gene Expression to Identify Functional Impact on Fetal Growth.

Peer reviewed: TrueFetal growth restriction (FGR) is a leading cause of perinatal morbidity and mortality. Altered placental formation and functional capacity are major contributors to FGR pathogenesis. Relating placental structure to function across the placenta in healthy and FGR pregnancies remains largely unexplored but could improve understanding of placental diseases. We investigated integration of these parameters spatially in the term human placenta using predictive modelling. Systematic sampling was able to overcome heterogeneity in placental morphological and molecular features. Defects in villous development, elevated fibrosis, and reduced expression of growth and functional marker genes (IGF2, VEGA, SLC38A1, and SLC2A3) were seen in age-matched term FGR versus healthy control placentas. Characteristic histopathological changes with specific accompanying molecular signatures could be integrated through computational modelling to predict if the placenta came from a healthy or FGR pregnancy. Our findings yield new insights into the spatial relationship between placental structure and function and the etiology of FGR

Integrated Placental Modelling of Histology with Gene Expression to Identify Functional Impact on Fetal Growth.

Fetal growth restriction (FGR) is a leading cause of perinatal morbidity and mortality. Altered placental formation and functional capacity are major contributors to FGR pathogenesis. Relating placental structure to function across the placenta in healthy and FGR pregnancies remains largely unexplored but could improve understanding of placental diseases. We investigated integration of these parameters spatially in the term human placenta using predictive modelling. Systematic sampling was able to overcome heterogeneity in placental morphological and molecular features. Defects in villous development, elevated fibrosis, and reduced expression of growth and functional marker genes (IGF2, VEGA, SLC38A1, and SLC2A3) were seen in age-matched term FGR versus healthy control placentas. Characteristic histopathological changes with specific accompanying molecular signatures could be integrated through computational modelling to predict if the placenta came from a healthy or FGR pregnancy. Our findings yield new insights into the spatial relationship between placental structure and function and the etiology of FGR

Cohort profile : Singapore Preconception Study of Long-Term Maternal and Child Outcomes (S-PRESTO)

The Singapore Preconception Study of Long-Term Maternal and Child Outcomes (S-PRESTO) is a preconception, longitudinal cohort study that aims to study the effects of nutrition, lifestyle, and maternal mood prior to and during pregnancy on the epigenome of the offspring and clinically important outcomes including duration of gestation, fetal growth, metabolic and neural phenotypes in the offspring. Between February 2015 and October 2017, the S-PRESTO study recruited 1039 Chinese, Malay or Indian (or any combinations thereof) women aged 18–45 years and who intended to get pregnant and deliver in Singapore, resulting in 1032 unique participants and 373 children born in the cohort. The participants were followed up for 3 visits during the preconception phase and censored at 12 months of follow up if pregnancy was not achieved (N = 557 censored). Women who successfully conceived (N = 475) were characterised at gestational weeks 6–8, 11–13, 18–21, 24–26, 27–28 and 34–36. Follow up of their index offspring (N = 373 singletons) is on-going at birth, 1, 3 and 6 weeks, 3, 6, 12, 18, 24 and 36 months and beyond. Women are also being followed up post-delivery. Data is collected via interviewer-administered questionnaires, metabolic imaging (magnetic resonance imaging), standardized anthropometric measurements and collection of diverse specimens, i.e. blood, urine, buccal smear, stool, skin tapes, epithelial swabs at numerous timepoints. S-PRESTO has extensive repeated data collected which include genetic and epigenetic sampling from preconception which is unique in mother–offspring epidemiological cohorts. This enables prospective assessment of a wide array of potential determinants of future health outcomes in women from preconception to post-delivery and in their offspring across the earliest development from embryonic stages into early childhood. In addition, the S-PRESTO study draws from the three major Asian ethnic groups that represent 50% of the global population, increasing the relevance of its findings to global efforts to address non-communicable diseases