Maternal-fetal unit interactions and eutherian neocortical development and evolution

Immunologic aspects of preeclampsia

Preeclampsia is a syndrome with multiple etiologies. The diagnosis can be made without proteinuria in the presence of dysfunction of at least 1 organ associated with hypertension. The common pathophysiological pathway includes endothelial cell activation, intravascular inflammation, and syncytiotrophoblast stress. There is evidence to support, among others, immunologic causes of preeclampsia. Unlike defense immunology, reproductive immunology is not based on immunologic recognition systems of self/non-self and missing-self but on immunotolerance and maternal-fetal cellular interactions. The main mechanisms of immune escape from fetal to maternal immunity at the maternal-fetal interface are a reduction in the expression of major histocompatibility complex molecules by trophoblast cells, the presence of complement regulators, increased production of indoleamine 2,3-dioxygenase, activation of regulatory T cells, and an increase in immune checkpoints. These immune protections are more similar to the immune responses observed in tumor biology than in allograft biology. The role of immune and nonimmune decidual cells is critical for the regulation of trophoblast invasion and vascular remodeling of the uterine spiral arteries. Regulatory T cells have been found to play an important role in suppressing the effectiveness of other T cells and contributing to local immunotolerance. Decidual natural killer cells have a cytokine profile that is favored by the presence of HLA-G and HLA-E and contributes to vascular remodeling. Studies on the evolution of mammals show that HLA-E, HLA-G, and HLA-C1/C2, which are expressed by trophoblasts and their cognate receptors on decidual natural killer cells, are necessary for the development of a hemochorial placenta with vascular remodeling. The activation or inhibition of decidual natural killer cells depends on the different possible combinations between killer cell immunoglobulin-like receptors, expressed by uterine natural killer cells, and the HLA-C1/C2 antigens, expressed by trophoblasts. Polarization of decidual macrophages in phenotype 2 and decidualization of stromal cells are also essential for high-quality vascular remodeling. Knowledge of the various immunologic mechanisms required for adequate vascular remodeling and their dysfunction in case of preeclampsia opens new avenues of research to identify novel biological markers or therapeutic targets to predict or prevent the onset of preeclampsia.

Molecular pathways in placental-fetal development and disruption

The first trimester of pregnancy ranks high in priority when minimizing harmful exposures, given the wide-ranging types of organogenesis occurring between 4- and 12-weeks' gestation. One way to quantify potential harm to the fetus in the first trimester is to measure a corollary effect on the placenta. Placental biomarkers are widely present in maternal circulation, cord blood, and placental tissue biopsied at birth or at the time of pregnancy termination. Here we evaluate ten diverse pathways involving molecules expressed in the first trimester human placenta based on their relevance to normal fetal development and to the hypothesis of placental-fetal endocrine disruption (perturbation in development that results in abnormal endocrine function in the offspring), namely: human chorionic gonadotropin (hCG), thyroid hormone regulation, peroxisome proliferator activated receptor protein gamma (PPARγ), leptin, transforming growth factor beta, epiregulin, growth differentiation factor 15, small nucleolar RNAs, serotonin, and vitamin D. Some of these are well-established as biomarkers of placental-fetal endocrine disruption, while others are not well studied and were selected based on discovery analyses of the placental transcriptome. A literature search on these biomarkers summarizes evidence of placenta-specific production and regulation of each biomarker, and their role in fetal reproductive tract, brain, and other specific domains of fetal development. In this review, we extend the theory of fetal programming to placental-fetal programming.

Vascular Regulation of Developmental Neurogenesis

Evolutionary studies indicate that the nervous system evolved prior to the vascular system, but the increasing complexity of organisms prompted the vascular system to emerge in order to meet the growing demand for oxygen and nutrient supply. In recent years, it has become apparent that the symbiotic communication between the nervous and the vascular systems goes beyond the exclusive covering of the demands on nutrients and oxygen carried by blood vessels. Indeed, this active interplay between both systems is crucial during the development of the central nervous system (CNS). Several neural-derived signals that initiate and regulate the vascularization of the CNS have been described, however less is known about the vascular signals that orchestrate the development of the CNS cytoarchitecture. Here, we focus on reviewing the effects of blood vessels in the process of neurogenesis during CNS development in vertebrates. In mammals, we describe the spatiotemporal features of vascular-driven neurogenesis in two brain regions that exhibit different neurogenic complexity in their germinal zone, the hindbrain and the forebrain.

Phosphate, Calcium, and Vitamin D: Key Regulators of Fetal and Placental Development in Mammals

Normal calcium and bone homeostasis in the adult is virtually fully explained by the interactions of several key regulatory hormones, including parathyroid hormone, 1,25 dihydroxy vitamin D3, fibroblast growth factor-23, calcitonin, and sex steroids (estradiol and testosterone). In utero, bone and mineral metabolism is regulated differently from the adult. During development, it is the placenta and not the fetal kidneys, intestines, or skeleton that is the primary source of minerals for the fetus. The placenta is able to meet the almost inexhaustible needs of the fetus for minerals by actively driving the transport of calcium and phosphorus from the maternal circulation to the growing fetus. These fundamentally important minerals are maintained in the fetal circulation at higher concentrations than those in maternal blood. Maintenance of these inordinately higher fetal levels is necessary for the developing skeleton to accrue sufficient minerals by term. Importantly, in livestock species, prenatal mineralization of the skeleton is crucial for the high levels of offspring activity soon after birth. Calcium is required for mineralization, as well as a plethora of other physiological functions. Placental calcium and phosphate transport are regulated by several mechanisms that are discussed in this review. It is clear that phosphate and calcium metabolism is intimately interrelated and, therefore, placental transport of these minerals cannot be considered in isolation.

Human Cytomegalovirus Infection Changes the Pattern of Surface Markers of Small Extracellular Vesicles Isolated From First Trimester Placental Long-Term Histocultures

Extracellular vesicles (EVs) have increasingly been recognized as key players in a wide variety of physiological and pathological contexts, including during pregnancy. Notably, EVs appear both as possible biomarkers and as mediators involved in the communication of the placenta with the maternal and fetal sides. A better understanding of the physiological and pathological roles of EVs strongly depends on the development of adequate and reliable study models, specifically at the beginning of pregnancy where many adverse pregnancy outcomes have their origin. In this study, we describe the isolation of small EVs from a histoculture model of first trimester placental explants in normal conditions as well as upon infection by human cytomegalovirus. Using bead-based multiplex cytometry and electron microscopy combined with biochemical approaches, we characterized these small EVs and defined their associated markers and ultrastructure. We observed that infection led to changes in the expression level of several surface markers, without affecting the secretion and integrity of small EVs. Our findings lay the foundation for studying the functional role of EVs during early pregnancy, along with the identification of new predictive biomarkers for the severity and outcome of this congenital infection, which are still sorely lacking.

Uterine cellular changes during mammalian pregnancy and the evolution of placentation

There are many different forms of nutrient provision in viviparous (live bearing) species. The formation of a placenta is one method where the placenta functions to transfer nutrients from mother to fetus (placentotrophy), transfer waste from the fetus to the mother and respiratory gas exchange. Despite having the same overarching function, there are different types of placentation within placentotrophic vertebrates, and many morphological changes occur in the uterus during pregnancy to facilitate formation of the placenta. These changes are regulated in complex ways but are controlled by similar hormonal mechanisms across species. This review describes current knowledge of the morphological and molecular changes to the uterine epithelium preceding implantation among mammals. Our aim is to identify the commonalities and constraints of these cellular changes to understand the evolution of placentation in mammals and propose directions for future research. We compare and discuss the complex modifications to the ultrastructure of uterine epithelial cells and show that there are similarities in the changes to the cytoskeleton and gross morphology of the uterine epithelial cells, especially of the apical and lateral plasma membrane of the cells during the formation of a placenta in all eutherians and marsupials studied to date. We conclude that further research is needed to understand the evolution of placentation among viviparous mammals, particularly concerning the level of placental invasiveness, hormonal control and genetic underpinnings of pregnancy in marsupial taxa.

A toolkit for the application of placental-fetal molecular biomarkers in epidemiologic studies of the fetal origins of chronic disease

Purpose of review

In this review, we provide essential background knowledge and an analytical framework for the application of placental-fetal molecular biomarkers in fetal origins chronic disease epidemiology. The widely available and highly quantitative placental hormone human chorionic gonadotropin (hCG) is used as an example. hCG is currently used for diagnosing fetal genetic disorders; yet it can and should be expanded to understanding the fetal origins of chronic diseases. We provide justification and methods to do this.

Recent findings

Ten papers published in the last 5 years were identified with supportive findings relevant to the application of biomarkers of hCG in epidemiologic studies on the developmental origins of health and disease (DOHaD).

Summary

There is increasing and consistent evidence that placental-fetal biomarkers may be highly informative in observational studies, as exemplified by hCG, with the correct approaches for measurement and data analysis.

Association of foetal size and sex with porcine foeto-maternal interface integrin expression

Integrins regulate adhesion at the foeto-maternal interface by interacting with secreted phosphoprotein 1 (SPP1) and fibronectin (FN). It is hypothesised that impaired foetal growth of ‘runt’ piglets is linked to altered integrin signalling at the foeto-maternal interface. Placental and endometrial samples associated with the lightest and closest to mean litter weight (CTMLW) (gestational day (GD18, 30, 45, 60 and 90), of both sex (GD30, 45, 60 and 90) (n = 5–8 litters/GD), Large White × Landrace conceptuses or foetuses were obtained. The mRNA expression of the integrin subunits (ITG) ITGA2, ITGAV, ITGB1, ITGB3, ITGB5, ITGB6, ITGB8, SPP1 and FN was quantified by qPCR. Temporal changes in mRNA expression were observed, with different profiles in the two tissues. Endometrial ITGB1 (P ≤ 0.05, GD45) and SPP1 (P ≤ 0.05, all GD combined and GD60) expression was decreased in samples supplying the lightest compared to the CTMLW foetuses. Placentas supplying female foetuses had decreased expression of ITGB6 (GD45, P ≤ 0.05) and FN (GD90, P ≤ 0.05) compared to those supplying male foetuses. Endometrial samples supplying females had increased ITGB3 (P ≤ 0.05, GD60) and FN (P ≤ 0.05, GD30) expression and decreased SPP1 (P ≤ 0.05, GD60) expression compared to male foetuses. Correlations between mean within-gilt mRNA expression and percentage prenatal survival, number of live foetuses or conceptuses and percentage male foetuses were observed. This study has highlighted novel and dynamic associations between foetal size, sex and integrin subunit mRNA expression at the porcine foeto-maternal interface. Further studies should be performed to improve the understanding of the mechanisms behind these novel findings.

Putative Cellular and Molecular Roles of Zika Virus in Fetal and Pediatric Neuropathologies

Although the World Health Organization declared an end to the recent Zika virus (ZIKV) outbreak and its association with adverse fetal and pediatric outcome, on November 18, 2016, the virus still remains a severe public health threat. Laboratory experiments thus far supported the suspicions that ZIKV is a teratogenic agent. Evidence indicated that ZIKV infection cripples the host cells' innate immune responses, allowing productive replication and potential dissemination of the virus. In addition, studies suggest potential transplacental passage of the virus and subsequent selective targeting of neural progenitor cells (NPCs). Depletion of NPCs by ZIKV is associated with restricted brain growth. And while microcephaly can result from infection at any gestational stages, the risk is greater during the first trimester. Although a number of recent studies revealed some of specific molecular and cellular roles of ZIKV proteins of this mosquito-borne flavivirus, the mechanisms by which it produces it suspected pathophysiological effects are not completely understood. Thus, this review highlights the cellular and molecular evidence that implicate ZIKV in fetal and pediatric neuropathologies.

Associations between fetal size, sex and placental angiogenesis in the pig

Inadequate fetal growth cannot be remedied postnatally, leading to severe consequences for neonatal and adult development. It is hypothesized that growth restriction occurs due to inadequate placental vascularization. This study investigated the relationship between porcine fetal size, sex, and placental angiogenesis at multiple gestational days (GD). Placental samples supplying the lightest and closest to mean litter weight (CTMLW), male and female Large White X Landrace fetuses were obtained at GD30, 45, 60, and 90. Immunohistochemistry revealed increased chorioallantoic membrane CD31 staining in placentas supplying the lightest compared to those supplying the CTMLW fetuses at GD60. At GD90, placentas supplying the lightest fetuses had decreased CD31 staining in the chorioallantoic membrane compared to those supplying the CTMLW fetuses. The mRNA expression of six candidate genes with central roles at the feto-maternal interface increased with advancing gestation. At GD60, ACP5 expression was increased in placentas supplying the lightest compared to the CTMLW fetuses. At GD45, CD31 expression was decreased in placentas supplying the lightest compared to the CTMLW fetuses. In contrast, CD31 expression was increased in placentas supplying the lightest compared the CTMLW fetuses at GD60. In vitro endothelial cell branching assays demonstrated that placentas supplying the lightest and male fetuses impaired endothelial cell branching compared to placentas from the CTMLW (GD45 and 60) and female fetuses (GD60), respectively. This study has highlighted that placentas supplying the lightest and male fetuses have impaired angiogenesis. Importantly, the relationship between fetal size, sex, and placental vascularity is dynamic and dependent upon the GD investigated.

Prenatal imaging findings in fetal Zika virus infection

PURPOSE OF REVIEW

The aim of this review is to report the most recent observations concerning intrauterine Zika virus (ZIKV) infection and associated neuroimaging.

RECENT FINDINGS

ZIKV outbreak in Brazil in 2015 was associated with an impressive registration of cases of congenital microcephaly in women with symptoms suggestive of ZIKV infection. Clinical and laboratory testing for ZIKV and hypothetic etiopathogenetic mechanisms are described. Diagnostic tests on blood, urine and amniotic fluid should be performed in all mothers with symptoms suggestive of intrauterine ZIKV infection. ZIKV causes multiple teratogenic malformations, mainly affecting the developing brain.

SUMMARY

Neuroimaging investigation contributes to the prenatal detection of microcephaly and other brain abnormalities in cases of intrauterine ZIKV infection. Neuroimaging is based antenatally on two-dimensional and three-dimensional ultrasound and fetal MRI, whereas computed tomography scan is performed postnatally. Although neuropathology associated with intrauterine ZIKV infection is characterized by nonspecific findings of brain disorder, reduced cortical gyration and white-matter hypomyelination or dysmyelination and cerebellar hypoplasia have been consistently observed in the majority of fetuses and newborns. Prenatal or postnatal genetic workup should be carried out to exclude cases of primary microcephaly. Follow-up should rely upon MRI and computed tomography scan as well as neuropediatrician to better define developmental outcome in survivors.

Maternal urinary phthalates and sex-specific placental mRNA levels in an urban birth cohort

BACKGROUND

Prenatal urinary concentrations of phthalates in women participants in an urban birth cohort were associated with outcomes in their children related to neurodevelopment, autoimmune disease risk, and fat mass at 3,5,7, and 8 years of life. Placental biomarkers and outcomes at birth may offer biologic insight into these associations. This is the first study to address these associations with candidate genes from the phthalate and placenta literature, accounting for sex differences, and using absolute quantitation methods for mRNA levels.

METHODS

We measured candidate mRNAs in 180 placentas sampled at birth (HSD17B1, AHR, CGA, CYP19A1, SLC27A4, PTGS2, PPARG, CYP11A1) by quantitative PCR and an absolute standard curve. We estimated associations of log_e mRNA with quartiles of urinary phthalate monoesters using linear mixed models. Phthalate metabolites (N = 358) and mRNAs (N = 180) were transformed to a z-score and modeled as independent, correlated vectors in relation to large for gestational age (LGA) and gestational diabetes mellitus (GDM).

RESULTS

CGA was associated with 4 out of 6 urinary phthalates. CGA was 2.0 log_e units lower at the 3^rd vs. 1^st quartile of mono-n-butyl phthalate (MnBP) (95% confidence interval (CI): -3.5, -0.5) in male placentas, but 0.6 log_e units higher (95% CI: -0.8, 1.9) in female placentas (sex interaction p = 0.01). There was an inverse association of MnBP with PPARG in male placentas (-1.1 log_e units at highest vs. lowest quartile, 95% CI: -2.0, -0.1). CY19A1, CYP11A1, CGA were associated with one or more of the following in a sex-specific manner: monobenzyl phthalate (MBzP), MnBP, mono-iso-butyl phthalate (MiBP). These 3 mRNAs were lower by 1.4-fold (95% CI: -2.4, -1.0) in male GDM placentas vs. female and non-GDM placentas (p-value for interaction = 0.04). The metabolites MnBP/MiBP were 16% higher (95% CI: 0, 22) in GDM pregnancies.

CONCLUSIONS

Prenatal concentrations of certain phthalates and outcomes at birth were modestly associated with molecular changes in fetal placental tissue during pregnancy. Associations were stronger in male vs. female placentas, and associations with MnBP and MiBP were stronger than other metabolites. Placental mRNAs are being pursued further as potential mediators of exposure-induced risks to the health of the child.

Evolutionary Developmental Biology (Evo-Devo) Research in Latin America

Famous for its blind cavefish and Darwin's finches, Latin America is home to some of the richest biodiversity hotspots of our planet. The Latin American fauna and flora inspired and captivated naturalists from the nineteenth and twentieth centuries, including such notable pioneers such as Fritz Müller, Florentino Ameghino, and Léon Croizat who made a significant contribution to the study of embryology and evolutionary thinking. But, what are the historical and present contributions of the Latin American scientific community to Evo-Devo? Here, we provide the first comprehensive overview of the Evo-Devo laboratories based in Latin America and describe current lines of research based on endemic species, focusing on body plans and patterning, systematics, physiology, computational modeling approaches, ecology, and domestication. Literature searches reveal that Evo-Devo in Latin America is still in its early days; while showing encouraging indicators of productivity, it has not stabilized yet, because it relies on few and sparsely distributed laboratories. Coping with the rapid changes in national scientific policies and contributing to solve social and health issues specific to each region are among the main challenges faced by Latin American researchers. The 2015 inaugural meeting of the Pan-American Society for Evolutionary Developmental Biology played a pivotal role in bringing together Latin American researchers eager to initiate and consolidate regional and worldwide collaborative networks. Such networks will undoubtedly advance research on the extremely high genetic and phenotypic biodiversity of Latin America, bound to be an almost infinite source of amazement and fascinating findings for the Evo-Devo community.

Teratogenic effects of the Zika virus and the role of the placenta

The mechanism by which the Zika virus can cause fetal microcephaly is not known. Reports indicate that Zika is able to evade the normal immunoprotective responses of the placenta. Microcephaly has genetic causes, some associated with maternal exposures including radiation, tobacco smoke, alcohol, and viruses. Two hypotheses regarding the role of the placenta are possible: one is that the placenta directly conveys the Zika virus to the early embryo or fetus. Alternatively, the placenta itself might be mounting a response to the exposure; this response might be contributing to or causing the brain defect. This distinction is crucial to the diagnosis of fetuses at risk and the design of therapeutic strategies to prevent Zika-induced teratogenesis.

Intrauterine Growth Restriction, Head Size at Birth, and Outcome in Very Preterm Infants

OBJECTIVES

To determine whether small head circumference (HC) or birth weight (BW) or both are associated with neonatal and long-term neurologic outcome in very preterm infants.

STUDY DESIGN

All 2442 live births from the 1997 Epipage study between 26 and 32 weeks of gestational age in 9 regions of France were analyzed. A total of 1395 were tested at age 5 years for cognitive performance and 1315 with school performance reports at age 8 years. Symmetric growth restriction (SGR) was defined by HC and BW <20th percentile and in the same percentile range, and asymmetric growth restriction by at least 1 of HC and BW <20th percentile and the other in a higher decile range. There were 2 forms of asymmetric growth restriction: head growth restriction (HGR) and weight growth restriction (WGR). Appropriate for gestational age was defined by both BW and HC >20th percentile.

RESULTS

Compared with appropriate for gestational age, SGR was significantly associated with neonatal mortality (aOR 2.99, 95% CI 1.78-5.03), moderate and severe cognitive deficiency (aOR 1.65, 95% CI 1.01-2.71 and aOR 2.61, 95% CI 1.46-4.68, respectively), and poor school performance (aOR 1.79; 95% CI 1.13-2.83). HGR was significantly associated with severe cognitive deficiency (aOR 2.07, 95% CI 1.15-3.74). WGR was not significantly associated with cognitive or school performance despite higher rates of neonatal morbidity.

CONCLUSIONS

SGR in preterm infants was associated with neonatal mortality and impaired cognitive and school performance. The outcome of asymmetric growth restriction differed according to HC. HGR was associated with impaired cognitive function; WGR was not.

Vital and vulnerable functions of the primate placenta critical for infant health and brain development

The placenta is essential to mammalian pregnancy with many roles beyond just nutrient supply, including both endocrine and immune functions. During the course of evolution, the placenta of higher primates has acquired some unique features, including the capacity to secrete corticotropin-releasing hormone (CRH). In addition, a placental receptor for IgG enables particularly high levels of protective maternal antibody to reach the fetus before birth. This paper reviews the placental biology of primates, and discusses its involvement in adrenocortical hormone activity during pregnancy, the transfer of maternal antibody, and finally the delivery of maternal iron to the fetus, which is needed for normal brain development. An understanding of these vital functions during a full-term, healthy pregnancy provides insights into the consequences of gestational disturbances, such as maternal stress, illness, and undernutrition, which have even larger ramifications if the infant is born premature.