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The prevalence of maternal obesity rapidly increases, which represents a major public health concern worldwide. Maternal obesity is characteristic by metabolic dysfunction and chronic inflammation. It is associated with health problems in both mother and offspring. Increasing evidence indicates that the placenta is an axis connecting maternal obesity with poor outcomes in the offspring. In this brief review, we have summarized the current data regarding deregulated placental function in maternal obesity. The data show that maternal obesity induces numerous placental defects, including lipid and glucose metabolism, stress response, inflammation, immune regulation and epigenetics. These placental defects affect each other and result in a stressful intrauterine environment, which transduces and mediates the adverse effects of maternal obesity to the fetus. Further investigations are required to explore the exact molecular alterations in the placenta in maternal obesity, which may pave the way to develop specific interventions for preventing epigenetic and metabolic programming in the fetus., (© 2024. The Author(s).)

Caspases, a family of cysteine proteases, are pivotal regulators of apoptosis, the tightly controlled cell death process crucial for eliminating excessive or unnecessary cells during development, including placental development. Collecting research has unveiled the multifaceted roles of caspases in the placenta, extending beyond apoptosis. Apart from their involvement in placental tissue remodeling via apoptosis, caspases actively participate in essential regulatory processes, such as trophoblast fusion and differentiation, significantly influencing placental growth and functionality. In addition, growing evidence indicates an elevation in caspase activity under pathological conditions like pre-eclampsia (PE) and intrauterine growth restriction (IUGR), leading to excessive cell death as well as inflammation. Drawing from advancements in caspase research and placental development under both normal and abnormal conditions, we examine the significance of caspases in both cell death (apoptosis) and non-cell death-related processes within the placenta. We also discuss potential therapeutics targeting caspase-related pathways for placenta disorders., Competing Interests: Declaration of competing interest The work described in this review article was conducted in an unbiased manner, and no external influences have affected the research process or the reporting of its outcomes. The authors have no financial, personal, or professional conflicts of interest that could inappropriately influence or compromise the integrity of the research presented in the manuscript., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: Does an elevation in d-Galactose (D-Gal) levels within the body contribute to abnormal embryonic development and placental dysfunction during pregnancy?, Methods: Mouse embryos were cultivated to the blastocyst stage under varying concentrations of D-Gal. The blastocyst formation rate was measured, and the levels of reactive oxygen species (ROS), sirtuin 1 (SIRT1), and forkhead box O3a (FOXO3a) in blastocysts were assessed. Mice were intraperitoneally injected with either saline or D-Gal with or without SRT1720. On the 14th day of pregnancy, the fetal absorption rate and placental weight were recorded. Placental levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were determined. The expression of senescence-related factors, such as senescence-associated β-galactosidase (SA-β-gal) in the placenta was examined, and the expression of placental SIRT1, FOXO3a and p21 was evaluated by immunohistochemistry and Western blotting., Results: D-Gal adversely affects early embryonic development in vitro, resulting in a decreased blastocyst formation rate. Furthermore, D-Gal downregulates SIRT1 and FOXO3a while increasing ROS levels in blastocysts. Concurrently, D-Gal induces placental dysfunction, characterized by an elevated fetal absorption rate, reduced placental weight, diminished SOD activity, and increased MDA content. The senescence-related factor SA-β-gal was detected in the placenta, along with altered expression of placental SIRT1, FOXO3a, and p21. The SIRT1 agonist SRT1720 mitigated this damage by increasing SIRT1 and FOXO3a expression., Discussion: The inhibition of early embryonic development and placental dysfunction induced by D-Gal may be attributed to the dysregulation of SIRT1. Activating SIRT1 emerges as a potentially effective strategy for alleviating the adverse effects of D-Gal exposure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Epidemiological studies suggest that fetal growth restriction (FGR) caused by gestational cholestasis is associated with elevated serum cholic acid (CA). Here, we explore the mechanism by which CA induces FGR. Pregnant mice except controls were orally administered with CA daily from gestational day 13 (GD13) to GD17. Results found that CA exposure decreased fetal weight and crown-rump length, and increased the incidence of FGR in a dose-dependent manner. Furthermore, CA caused placental glucocorticoid (GC) barrier dysfunction via down-regulating the protein but not the mRNA level of placental 11β-Hydroxysteroid dehydrogenase-2 (11β-HSD2). Additionally, CA activated placental GCN2/eIF2α pathway. GCN2iB, an inhibitor of GCN2, significantly inhibited CA-induced down-regulation of 11β-HSD2 protein. We further found that CA caused excessive reactive oxygen species (ROS) production and oxidative stress in mouse placentas and human trophoblasts. NAC significantly rescued CA-induced placental barrier dysfunction by inhibiting activation of GCN2/eIF2α pathway and subsequent down-regulation of 11β-HSD2 protein in placental trophoblasts. Importantly, NAC rescued CA-induced FGR in mice. Overall, our results suggest that CA exposure during late pregnancy induces placental GC barrier dysfunction and subsequent FGR may be via ROS-mediated placental GCN2/eIF2α activation. This study provides valuable insight for understanding the mechanism of cholestasis-induced placental dysfunction and subsequent FGR., (© 2023 Federation of American Societies for Experimental Biology.)

Despite the indispensable role of the placenta in the successful course of pregnancy, regulation of its dynamic transcriptome is still underexplored. The purpose of this literature review was to give an overview and draw attention to the contribution of genetic variation in shaping the human placental gene expression. Studies of placental transcriptome shaped by chromosomal variants are limited and may be confounded by cellular mosaicism and somatic genomic rearrangements. Even in relatively simple cases, such as aneuploidies, the placental transcriptome appears to differ from the assumed systematically increased transcript levels of the involved chromosomes. Single nucleotide variants modulating placental gene expression referred to as expression quantitative trait loci (eQTLs) have been analyzed only in ten candidate gene and three genome-wide association studies (GWAS). The latter identified 417 confident placental eGenes, supported by at least two independent studies. Functional profiling of eGenes highlighted biological pathways important in pregnancy, such as immune response or transmembrane transport activity. A fraction of placental eQTLs (1-3%) co-localize with GWAS loci for adult disorders (metabolic, immunological, neurological), suggesting a co-contributory role of the placenta in the developmental programming of health. Some placental eQTLs have been identified as risk factors for adverse pregnancy outcomes, such as rs4769613 (C > T), located near the FLT1 gene and confidently associated with preeclampsia. More studies are needed to map genetic variants shaping gene expression in different placental cell types across three trimesters in normal and complicated gestations and to clarify to what extent these heritable factors contribute to maternal and offspring disease risks., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Macrophage migration inhibitory factor (MIF) is a versatile cytokine acting as an important regulator of innate and adaptive immunity and implicated in many physiological and pathological processes. It is abundantly expressed at the feto-maternal interface and proposed to have a role in establishing and maintaining a healthy pregnancy. This review presents the current literature data regarding the MIF role in early pregnancy events and its association with some of the placental pathological conditions, including infection, preeclampsia, gestational diabetes mellitus and choriocarcinoma. General information regarding MIF structure and function is followed by an overview of its expression in reproductive tissues and in pregnancy. Futher, we discuss MIF's involvement in the survival of decidual stromal cells, placenta of the first trimester of pregnancy, and in trophoblast cell functions studied in vitro. Current findings associating this cytokine to placental infection, preeclampsia, gestational diabetes mellitus and choriocarcinoma are presented in the final part., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Nuclear Receptor Subfamily 4 Group A Member 2 (NR4A2) transcripts are elevated in the circulation of individuals whose pregnancies are complicated by preterm fetal growth restriction (FGR). In this paper, we show that the cases with preeclampsia (PE) have increased circulating NR4A2 transcripts compared to those with normotensive FGR. We aimed to establish whether the dysfunctional placenta mirrors the increase in NR4A2 transcripts and further, to uncover the function of placental NR4A2. NR4A2 expression was detected in preterm and term placental tissue; expressed higher at term. NR4A2 mRNA expression and protein were not altered in placentas from preterm FGR or PE pregnancies. Hypoxia (1% O 2 compared to 8% O 2 ) significantly reduced cytotrophoblast NR4A2 mRNA expression, but not placental explant NR4A2 expression. Silencing cytotrophoblast NR4A2 expression under hypoxia (via short interfering (si)RNAs) did not alter angiogenic Placental Growth Factor, nor anti-angiogenic sFlt-1 mRNA expression or protein secretion, but increased expression of cellular antioxidant, oxidative stress, inflammatory, and growth genes. NR4A2 expression was also not altered in a model of tumour necrosis factor-α-induced endothelial dysfunction, or with pravastatin treatment. Further studies are required to identify the origin of the circulating transcripts in pathological pregnancies, and investigate the function of placental NR4A2., (© 2021. The Author(s).)

A well-functioning placenta is crucial for normal gestation and regulates the nutrient, gas, and waste exchanges between the maternal and fetal circulations and is an important endocrine organ producing hormones that regulate both the maternal and fetal physiologies during pregnancy. Placental insufficiency is implicated in spontaneous preterm birth (SPTB). We proposed that deficits in the capacity of the placenta to maintain bioenergetic and metabolic stability during pregnancy may ultimately result in SPTB. To explore our hypothesis, we performed a RNA-seq study in male and female placentas from women with SPTB (<36 weeks gestation) compared to normal pregnancies (≥38 weeks gestation) to assess the alterations in the gene expression profiles. We focused exclusively on Black women (cases and controls), who are at the highest risk of SPTB. Six hundred and seventy differentially expressed genes were identified in male SPTB placentas. Among them, 313 and 357 transcripts were increased and decreased, respectively. In contrast, only 61 differentially expressed genes were identified in female SPTB placenta. The ingenuity pathway analysis showed alterations in the genes and canonical pathways critical for regulating inflammation, oxidative stress, detoxification, mitochondrial function, energy metabolism, and the extracellular matrix. Many upstream regulators and master regulators important for nutrient-sensing and metabolism were also altered in SPTB placentas, including the PI3K complex, TGFB1/SMADs, SMARCA4, TP63, CDKN2A, BRCA1, and NFAT. The transcriptome was integrated with published human placental metabolome to assess the interactions of altered genes and metabolites. Collectively, significant and biologically relevant alterations in the transcriptome were identified in SPTB placentas with fetal sex disparities. Altered energy metabolism, mitochondrial function, inflammation, and detoxification may underly the mechanisms of placental dysfunction in SPTB.

Biomarkers for placental dysfunction are currently lacking. We recently identified SPINT1 as a novel biomarker; SPINT2 is a functionally related placental protease inhibitor. This study aimed to characterise SPINT2 expression in placental insufficiency. Circulating SPINT2 was assessed in three prospective cohorts, collected at the following: (1) term delivery ( n = 227), (2) 36 weeks ( n = 364), and (3) 24-34 weeks' ( n = 294) gestation. SPINT2 was also measured in the plasma and placentas of women with established placental disease at preterm (<34 weeks) delivery. Using first-trimester human trophoblast stem cells, SPINT2 expression was assessed in hypoxia/normoxia (1% vs. 8% O2), and following inflammatory cytokine treatment (TNFα, IL-6). Placental SPINT2 mRNA was measured in a rat model of late-gestational foetal growth restriction. At 36 weeks, circulating SPINT2 was elevated in patients who later developed preeclampsia ( p = 0.028; median = 2233 pg/mL vs. controls, median = 1644 pg/mL), or delivered a small-for-gestational-age infant ( p = 0.002; median = 2109 pg/mL vs. controls, median = 1614 pg/mL). SPINT2 was elevated in the placentas of patients who required delivery for preterm preeclampsia ( p = 0.025). Though inflammatory cytokines had no effect, hypoxia increased SPINT2 in cytotrophoblast stem cells, and its expression was elevated in the placental labyrinth of growth-restricted rats. These findings suggest elevated SPINT2 is associated with placental insufficiency.

Cervical remodeling is a critical component in both term and preterm labor in eutherian mammals. However, the molecular mechanisms underlying cervical remodeling remain poorly understood in the mare. The current study compared the transcriptome of the equine cervix (cervical mucosa (CM) and stroma (CS)) during placentitis (placentitis group, n = 5) and normal prepartum mares (prepartum group, n = 3) to normal pregnant mares (control group, n = 4). Transcriptome analysis identified differentially expressed genes (DEGs) during placentitis (5310 in CM and 907 in CS) and during the normal prepartum period (189 in CM and 78 in CS). Our study revealed that cervical remodeling during placentitis was dominated by inflammatory signaling as reflected by the overrepresented toll-like receptor signaling, interleukin signaling, T cell activation, and B cell activation pathways. These pathways were accompanied by upregulation of several proteases, including matrix metalloproteinases (MMP1, MMP2, and MMP9), cathepsins (CTSB, CTSC, and CTSD) and a disintegrin and metalloproteinase with thrombospondin type 1 motifs (ADAMTS1, ADAMTS4, and ADAMTS5), which are crucial for degradation of cervical collagens during remodeling. Cervical remodeling during placentitis was also associated with upregulation of water channel-related transcripts (AQP9 and RLN), angiogenesis-related transcripts (NOS3, ENG1, THBS1, and RAC2), and aggrecan (ACAN), a hydrophilic glucosaminoglycan, with subsequent cervical hydration. The normal prepartum cervix was associated with upregulation of ADAMTS1, ADAMTS4, NOS3 and THBS1, which might reflect an early stage of cervical remodeling taking place in preparation for labor. In conclusion, our findings revealed the possible key regulators and mechanisms underlying equine cervical remodeling during placentitis and the normal prepartum period.

Improved understanding of the molecular mechanisms underlying ascending equine placentitis holds the potential for the development of new diagnostic tools and therapies to forestall placentitis-induced preterm labor. The current study characterized the equine placental transcriptome (chorioallantois [CA] and endometrium [EN]) during placentitis (placentitis group, n = 6) in comparison to gestationally-matched controls (control group, n = 6). Transcriptome analysis identified 2953 and 805 differentially expressed genes in CA and EN during placentitis, respectively. Upstream regulator analysis revealed the central role of toll-like receptors (TLRs) in triggering the inflammatory signaling, and consequent immune-cell chemotaxis. Placentitis was associated with the upregulation of matrix metalloproteinase (MMP1, MMP2, and MMP9) and apoptosis-related genes such as caspases (CASP3, CASP4, and CASP7) in CA. Also, placentitis was associated with downregulation of transcripts coding for proteins essential for placental steroidogenesis (SRD5A1 and AKR1C1), progestin signaling (PGRMC1 and PXR) angiogenesis (VEGFA, VEGFR2, and VEGFR3), and nutrient transport (GLUT12 and SLC1A4), as well as upregulation of hypoxia-related genes (HIF1A and EGLN3), which could explain placental insufficiency during placentitis. Placentitis was also associated with aberrant expression of several placenta-regulatory genes, such as PLAC8, PAPPA, LGALS1, ABCG2, GCM1, and TEPP, which could negatively affect placental functions. In conclusion, our findings revealed for the first time the key regulators and mechanisms underlying placental inflammation, separation, and insufficiency during equine placentitis, which might lead to the development of efficacious therapies or diagnostic aids by targeting the key molecular pathways., (© The Author(s) 2020. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Placentation is a major determinant of the success of pregnancy. It is regulated by several factors such as cell adhesion molecules, tight junctions, and gap junctions. The cell adhesion molecules are integrins, cadherins, immunoglobulins, nectins, and selectins. The tight junctions are composed of claudins, occludin, and junction adhesion molecule proteins while the gap junctions are composed of connexins of varying molecular weights. During placentation, some of these molecules regulate trophoblast proliferation, trophoblast fusion, trophoblast migration, trophoblast invasion, trophoblast-endothelium adhesion, glandular remodeling, and spiral artery remodeling. There is a dysregulated placental expression of some of these molecules during obstetric complications. We have, hereby, indicated the expression patterns of the subunits of each of these molecules in the various trophoblast subtypes and in the decidua, and have highlighted their involvement in physiological and pathological placentation. The available evidence points to the relevance of these molecules as distinguishing markers of the various trophoblast lineages and as potential therapeutic targets in the management of malplacentation-mediated diseases.

Monitoring the health of a pregnancy is of utmost importance to both the fetus and the mother. The diagnosis of pregnancy complications typically occurs after the manifestation of symptoms, and limited preventative measures or effective treatments are available. Traditionally, pregnancy health is evaluated by analyzing maternal serum hormone levels, genetic testing, ultrasonographic imaging, and monitoring maternal symptoms. However, researchers have reported a difference in extracellular vesicle (EV) quantity and cargo between healthy and at-risk pregnancies. Thus, placental EVs (PEVs) may help to understand normal and aberrant placental development, monitor pregnancy health in terms of developing placental pathologies, and assess the impact of environmental influences, such as infection, on pregnancy. The diagnostic potential of PEVs could allow for earlier detection of pregnancy complications via noninvasive sampling and frequent monitoring. Understanding how PEVs serve as a means of communication with maternal cells and recognizing their potential utility as a readout of placental health have sparked a growing interest in basic and translational research. However, to date, PEV research with animal models lags behind human studies. The strength of animal pregnancy models is that they can be used to assess placental pathologies in conjunction with isolation of PEVs from fluid samples at different time points throughout gestation. Assessing PEV cargo in animals within normal and complicated pregnancies will accelerate the translation of PEV analysis into the clinic for potential use in prognostics. We propose that appropriate animal models of human pregnancy complications must be established in the PEV field., (© The Author(s) 2020. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Introduction: Abnormal levels of first trimester placental biomarkers are associated with the development of placental syndrome (PS). However, prediction performance is moderate, possibly explained by the clinical heterogeneity of PS. Aim of this study is to investigate the association between first trimester biomarkers and the presence of maternal vascular malperfusion (MVM), as a marker for placental insufficiency., Methods: This retrospective study included 195 women with available first trimester blood sample and placenta histological sections for examination at the Maastricht University Medical Centre. Women were divided into 4 groups, based on the presence of having MVM lesions and/or PS. Levels of PAPP-A, PlGF and sFlt-1 were measured and MVM lesions were classified according to the Amsterdam Placental Workshop Group Consensus Statement., Results: MVM occurrence was observed in 32% of the uncomplicated pregnancies. Women with MVM (regardless of the PS) had lower levels of PAPP-A (p = 0.038) and sFLt-1 (p = 0.006), and a non-significant trend for lower PlGF and sFlt-1/PlGF ratio compared to women without MVM. Low PAPP-A levels individually and in combination with the presence of PS was significantly associated with MVM lesions (aOR = 3.0 and 6.1, respectively), as did the combination of low PlGF levels and PS (aOR = 4.6). In women with PS, having MVM increased the incidence of fetal growth restriction, small for gestational age neonates, lower birthweight and adverse neonatal outcome., Discussion: Our findings suggest that MVM lesions were found to be associated with increased obstetric risks due to early placental dysfunction that can potentially be predicted by the use of first trimester biomarkers., Competing Interests: Declaration of competing interest There are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Rare nodules of heterotopic adrenocortical and hepatic tissue are reported in the placenta. A mechanism for adrenocortical tissue in the placenta has been perplexing, while hepatic tissue is generally considered related to yolk sac primordia. The clear cell morphology of these nodules is similar to the adrenal cortex of the adult; however, the fetal adrenal gland does not usually display clear cells., Methods: We stained 9 placental nodules, histologically identical to "adrenocortical" heterotopia of the placenta, to determine whether adrenocortical differentiation could be confirmed. These cases include 3 archival cases initially diagnosed as "adrenocortical" heterotopia., Results: Immunohistochemical staining with steroid factor-1 (SF-1), HepPar-1, and Arginase-1 showed that these nodules of clear cells are actually hepatic (SF-1 negative, HepPar-1, and Arginase-1 positive). PAS staining suggests that glycogen accumulation is responsible for the clear cytoplasm. In contrast, a nodule of adrenocortical heterotopia near the testis and the adrenal gland from a 38-week-old neonatal autopsy case confirm SF-1 reactivity as expected., Conclusion: We propose that adrenocortical heterotopia in the placenta is a misnomer, and that these subchorionic nodules of clear cells demonstrate hepatic differentiation.

Objectives: An adequate development of the placenta includes trophoblast differentiation with the processes of trophoblast migration, invasion, cellular senescence and apoptosis which are all crucial to establishing a successful pregnancy. Altered placental development and function lead to placental diseases such as preeclampsia (PE) which is mainly characterized by insufficient trophoblast invasion and abnormally invasive placenta (AIP) disorders ( Placenta accreta , increta , or percreta) which are characterized by excessive trophoblast invasion. Both of them will cause maternal and fetal morbidity/mortality. However, the etiology of these diseases is still unclear. Our previous study has shown that the matricellular protein nephroblastoma overexpressed (NOV, CCN3) induces G0/G1 cell cycle arrest, drives trophoblast cells into senescence and activates FAK and Akt kinases resulting in reduced cell proliferation and enhanced migration capability of the human trophoblast cell line SGHPL-5. The present study focuses on whether CCN3 can alter cell cycle-regulated pathways associated with trophoblast senescence and invasion activity in pathological versus gestational age-matched control placentas., Methods: Cell cycle regulator proteins were investigated by immunoblotting and qPCR. For localization of CCN3, p16, p21, and Cyclin D1 proteins, co-immunohistochemistry was performed., Results: In early-onset PE placentas, CCN3 was expressed at a significantly lower level compared to gestational age-matched controls. The decrease of CCN3 level is associated with an increase in p53, Cyclin E1 and pRb protein expression, whereas the level of cleaved Notch-1, p21, Cyclin D1, pFAK, pAKT, and pmTOR protein decreased. In term AIP placentas, the expression of CCN3 was significantly increased compared to matched term controls. This increase was correlated to an increase in p53, p16, p21, Cyclin D1, cleaved Notch-1, pFAK, pAkt, and pmTOR whereas pRb was significantly decreased. However, in late PE and early AIP placentas, no significant differences in CCN3, p16, p21, Cyclin D1, p53, and cleaved Notch-1 expression were found when matched to appropriate controls., Conclusions: CCN3 expression levels are correlated to markers of cell cycle arrest oppositely in PE and AIP by activating the FAK/AKT pathway in AIP or down-regulating in PE. This may be one mechanism to explain the different pathological features of placental diseases, PE and AIP., (Copyright © 2020 Duan, Schimmelmann, Wu, Reisch, Faas, Kimmig, Winterhager, Köninger and Gellhaus.)

Polypeptide hormones and steroid hormones, either expressed by the placenta or dependant on the placenta for their synthesis, are key to driving adaptations in the mother during pregnancy that support growth in utero. These adaptations include changes in maternal behaviour that take place in pregnancy and after the birth to ensure that offspring receive appropriate care and nutrition. Placentally-derived hormones implicated in the programming of maternal caregiving in rodents include prolactin-related hormones and steroid hormones. Neuromodulators produced by the placenta may act directly on the fetus to support brain development. A number of imprinted genes function antagonistically in the placenta to regulate the development of key placental endocrine lineages expressing these hormones. Gain-in-expression of the normally maternally expressed gene Phlda2 or loss-of-function of the normally paternally expressed gene Peg3 results in fewer endocrine cells in the placenta, and pups are born low birth weight. Importantly, wild type dams carrying these genetically altered pups display alterations in their behaviour with decreased focus on nurturing (Phlda2) or heightened anxiety (Peg3). These same genes may regulate placental hormones in human pregnancies, with the potential to influence birth weight and maternal mood. Consequently, the aberrant expression of imprinted genes in the placenta may underlie the reported co-occurrence of low birth weight with maternal prenatal depression., (Copyright © 2020. Published by Elsevier Ltd.)

The placenta, a temporary organ that forms during pregnancy, is the largest fetal organ and the first to develop. It is recognized as an organ that plays a vital role as a metabolic and physical barrier in the fetoplacental unit; throughout fetal development it acts as the lungs, gut, kidneys, and liver of the fetus. When its two components, the fetal and the maternal one, successfully interact, pregnancy proceeds healthily. However, in some cases there may be pregnancy disorders, such as preeclampsia (PE) and gestational diabetes mellitus (GDM), which can lead to a different outcome for the mother and the newborn. In recent years, several studies have been conducted to try to understand how the expression of factors involved in the development of the placenta varies under pathological conditions compared with normal conditions. The purpose of this review is to summarize recent discoveries in this field., Competing Interests: Declaration of competing interest All authors confirm that they have no competing interest in the manuscript., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The placenta performs a range of crucial functions that support fetal growth during pregnancy, including facilitating the supply of oxygen and nutrients to the fetus, removal of waste products from the fetus and the endocrine modulation of maternal physiology. The placenta also stores glucose in the form of glycogen, the function of which remains unknown. Aberrant placental glycogen storage in humans is associated with maternal diabetes during pregnancy and pre-eclampsia, thus linking placental glycogen storage and metabolism to pathological pregnancies. To understand the role of placental glycogen in normal and complicated pregnancies, we must turn to animal models. Over 40 targeted mutations in mice demonstrate the defects in placental cells that store glycogen and suggest that placental glycogen represents a source of readily mobilized glucose required during periods of high fetal demand. However, direct functional evidence is currently lacking. Here, we evaluate these genetic mouse models with placental phenotypes that implicate glycogen trophoblast cell differentiation and function to illuminate the common molecular pathways that emerge and to better understand the relationship between placental glycogen and fetal growth. We highlight the current limitations in exploring the key questions regarding placental glycogen storage and metabolism and define how to experimentally overcome these constraints.

The placenta utilizes many mechanisms to protect the haploidentical fetus from recognition by the maternal immune system. However, in cases of villitis of unknown etiology (VUE), maternal lymphocytes gain access into the placenta, causing significant health risks for the fetus. Evidence suggests that VUE is a rejection response between the mother and the haploidentical fetus. Therefore, we profiled human leukocyte antigen (HLA), an important predictor of transplant rejection, in VUE using placental tissue from ten patients with VUE and ten gestational age matched controls. Placentas were stained using novel multiplexed immunofluorescence (MxIF) to investigate morphology and HLA classes I and II. Gene expression was evaluated by microarray, and where available, tissue typing of mother/baby pairs was completed to determine HLA type. MxIF demonstrated strong CD8+ T cell infiltration and HLA class I staining both the distal and stem villi of VUE placentas. Compared to controls, VUE cases had significantly higher expression of HLA class II mRNA and pathway analysis demonstrated that 40% of the differentially expressed genes in VUE are related to tissue rejection. The data suggest that VUE resembles a rejection response between the mother and the fetus. It remains unknown what initiates immune recognition and why some mothers appear to be at higher risk for developing this condition than others. Understanding this etiology will be critical for developing effective interventions or prevention strategies during pregnancy.

Introduction: Massive perivillous fibrin deposition (MPDD) is an uncommon placental lesion which has been associated with an increased risk of adverse pregnancy outcome in retrospective series. The purpose of the study was to evaluate the frequency and consequences of MPFD in pregnancies complicated by fetal growth restriction (FGR)., Materials and Methods: A cohort study of 355 pregnancies complicated by FGR diagnosed according to standard ultrasonographic criteria, enrolled, followed and delivered at a single obstetric unit. Pathological placental lesions were classified according to the Amsterdam Placental Workshop Consensus. Penalized logistic regression models were used to evaluate the association of MPFD with maternal risk factors, other pathological lesions and neonatal outcome., Results: The rates of moderate (25-50% of villi) and severe (>50% of villi) MPFD were 8.7% (31/355) and 3.1% (11/355), respectively. Compared to other FGR cases, MPFD pregnancies were characterized by higher placental volume (450 ± 144.5 SD as compared to 412.2 ± 151 cm 3 ,p < 0.001) and lower birthweight/placental weight ratio (5.32 ± 1.53 compared to 6.1 ± 1.52,p < 0.001). The rates of abnormal Doppler ultrasound studies of umbilical and middle cerebral artery were similar in MPFD subjects and controls. After correction for gestational age and birthweight, MPFD was associated with an increased risk of neonatal intraventricular hemorrhage (>grade II) (OR = 5.66,95% CI = 1.69-18.97), sepsis (OR = 5.9, 95% CI = 1.27-27.12), proven necrotizing enterocolitis (OR = 9.84,95% CI = 2.49-38.8) and overall severe adverse neonatal outcome (OR = 5.71,95% CI = 2.05-15.87)., Conclusions: Moderate-to-severe MPFD was relatively common among FGR pregnancies and was associated with morphometric modifications of placenta and with an increased risk of severe adverse neonatal outcome., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Statistically, patients with severe pregnancy complications are at risk of recurrent complications, but it is less understood if patients present with similar or different placental pathologies in subsequent pregnancies. In this case report, we describe 2 consecutive adverse pregnancies in the same woman 4 years apart. The first pregnancy was diagnosed as early-onset preeclampsia and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome, with placental maternal vascular malperfusion features, such as syncytial knots and accelerated villous maturity. In contrast, the second pregnancy was associated with normotensive fetal growth restriction and placental "immunological" lesions, such as massive perivillous fibrin deposition and chronic intervillositis. However, based on the expression of FLT1, LIMCH1, and TAP1 by quantitative polymerase chain reaction, the placentas from both pregnancies were found to exhibit an "immunological" transcriptional signature. This suggests that this small panel of gene expression markers may be able to predict the future reoccurrence of an immunological placental pathology despite no histological evidence within the first pregnancy. These results call for more studies looking at paired pregnancies of individuals with recurrent obstetric complications and confirm the importance of assessing matched transcriptional and histopathological placental information.

Prolactin family 7, subfamily d, member 1 (Prl7d1), a member of the expanding prolactin family, is mainly expressed in the placental junctional zone (including trophoblast giant cells and spongiotrophoblast cells) with peak expression observed at 12 days postcoitum (dpc) in mice. Previous studies have shown that PRL7D1 is a key mediator of angiogenesis in vitro; however, its physiological roles in placental development in vivo have not been characterized. To address this issue, we deleted Prl7d1 in mice and demonstrated that its absence results in reduced litter size and fertility. Histologically, Prl7d1 mutants exhibited striking placental abnormalities at 12.5 dpc, including a reduction in the proportion of labyrinth layers and a significant increase in decidual natural killer cells, glycogen trophoblasts, and trophoblast giant cells in the junctional zone. Moreover, placentas from Prl7d1-null mice displayed a thickened decidual spiral artery. Notably, these negative effects were more pronounced in male fetuses. Further RNA-sequencing analysis showed that Prl7d1 deletion results in significant differences in the placental transcriptome profile between the two sexes of fetuses. Together, this study demonstrates that Prl7d1 possesses antiangiogenic properties in deciduas and inhibits the development of junctional zone, which potentially alters the functional capacity of the placenta to support optimal fetal growth. Moreover, of note, the role of Prl7d1 in the placenta is regulated in a fetal sex-specific manner., (© 2019 Wiley Periodicals, Inc.)

Intrauterine infection and inflammation remain a major cause of preterm labour in women and mares, with little known about small RNA (sRNA) expression in tissue or circulation. To better characterise placental inflammation (placentitis), we examined sRNA expression in the endometrium, chorioallantois and serum of mares with and without placentitis. Disease was induced in 10 mares via intracervical inoculation of Streptococcus equi ssp. zooepidemicus, either with moderate or high levels of inoculum; three uninoculated gestationally matched mares were used as controls. Matched chorioallantois and endometrium were sampled in two locations: Region 1, gross inflammation near cervical star with placental separation and Region 2, gross inflammation without placental separation. In Region 1, 26 sRNAs were altered in chorioallantois, while 20 were altered in endometrium. Within Region 2, changes were more subdued in both chorioallantois (10 sRNAs) and endometrium (two sRNAs). Within serum, we identified nine significantly altered sRNAs. In summary, we have characterised the expression of sRNA in the chorioallantois, the endometrium and the serum of mares with experimentally induced placentitis using next-generation sequencing, identifying significant changes within each tissue examined. These data should provide valuable information about the physiology of placental inflammation to clinicians and researchers alike.

Exposure to intrauterine inflammation (IUI) is associated with short- and long-term adverse perinatal outcomes. However, little data exist on utilizing placenta to prognosticate fetal injury in this scenario. Our study aimed to utilize imaging modalities to evaluate mechanisms contributing to placental injury following IUI exposure and correlated it to concomitant fetal brain injury. CD1 pregnant dams underwent laparotomies and received intrauterine injections of either lipopolysaccharide (LPS; a model of IUI) or phosphate-buffered saline (PBS). In utero ultrasound Doppler velocimetry of uterine and umbilical arteries and magnetic resonance imaging (MRI) of placental volumes with confirmatory immunohistochemical (vimentin) and histochemistry (fibrin) analyses were performed. ELISA for thrombosis markers, fibrinogen and fibrin was performed to analyze thrombi in placenta. Fetal brain immunohistochemistry was performed to detect microglial activation (ionized calcium-binding adaptor molecule 1, Iba1). On ultrasound, LPS group demonstrated elevated resistance indices, pulsatility indices and a greater occurrence of absent end-diastolic flow in the umbilical and uterine arteries. In the fetus, there was an increased cardiac Tei indices in the LPS group. MRI revealed decreased volume of placenta in the LPS group associated with placental thinning and placental endothelial damage on immunohistochemistry. Decreased fibrinogen content and more thrombi staining in placenta exposed to maternal LPS indicated the hypercoagulability. Furthermore, the expression of Iba1was significantly associated with placental thickness (r = -0.7890, Pearson correlation coefficient). Our data indicate that IUI can trigger events leading to maternal placental malperfusion and fetal vessel resistance, as well as predispose the developing fetus to cardiac dysfunction and brain damage. Furthermore, our data suggest that prenatal ultrasound can be a real-time clinical tool for assessing fetal risk for adverse neurologic outcomes following the potential IUI exposure., Competing Interests: The authors have declared that no competing interests exist.

Introduction: Chronic histiocytic intervillositis of unknown etiology (CIUE) is a non-infectious, most probably immunologic placenta lesion. CIUE is associated with recurrent miscarriage, intrauterine growth restriction and stillbirth. Among the pathologic-anatomic defined placental lesions this entity displays the highest risk of recurrence in following pregnancies (about 67-100%). The histiocytic cells accumulate in the placental blood space but do not infiltrate into the villi or decidua. Sparsely known is the expression profile of these intervillous cells regarding histiocytic markers., Methods: We analysed 5-22 markers by immunohistochemistry in a total of 41 placenta samples and evaluated decidual, villous and intervillous histiocytic cells., Results: In CIUE, intervillous CD163 +  histiocytes over-express CD11c/CD18 and down-regulate CD206/CD209, while CD163 +  decidual and Hofbauer cells show low CD11c/CD18 and higher CD206/CD209 protein expressions., Discussion: CD163 expression indicates a M2-like polarisation. CD11c and CD18 form the complement receptor 4 which could be related to a complement mediated trigger for aberrant cell accumulation in CIUE., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Gestational diabetes affects almost 1 in 10 pregnancies and is associated with adverse outcomes including fetal demise. Pregnancy complications related to diabetes are attributed to placental vascular dysfunction. With diabetes, maternal hyperglycemia is thought to promote placental vasoconstriction. However, it remains poorly understood if and how hyperglycemia leads to placental vascular dysfunction or if humoral factors related to maternal diabetes are responsible., Methods and Results: Utilizing a human placenta dual cotyledon, dual perfusion assay we examined the arterial pressure response to the thromboxane mimetic U44619, in cotyledons exposed to normal vs. a hyperglycemic infusion into the intervillous space. Tissues were then analyzed for the activity of key signaling molecules related to vascular tone; eNOS, Akt, PKA and VEGFR2. Results indicate a significant increase in fetal vascular resistance with maternal exposure to hyperglycemia. This response corresponded with a reduction in the phosphorylation of eNOS at Ser1177 and Akt at Thr308. In contrast, VEGFR2 at Tyr1175 and PKA at Thr197 were not different with hyperglycemia., Conclusion: Reductions of eNOS and Akt phosphorylation at key residues implicated in nitric oxide production suggest that hyperglycemia alters the vasodilatory signaling of placental vessels. In contrast, acute hyperglycemic exposure may not alter vasoconstriction via VEGF and PKA signaling. Altogether our results link hyperglycemic exposure in human placentas to nitric oxide signaling; a mechanisms that may account for the elevations in vascular resistance commonly observed in diabetic pregnancies., (Published by Elsevier Ltd.)

The most important function of the placenta is the exchange of nutrients and oxygen between a mother and her fetus. To establish a healthy functioning placenta, placentation needs to occur with adequate remodelling of spiral arteries by extravillous trophoblasts. When this process is impaired, the resulting suboptimal and inadequate placenta function results in the manifestation of pregnancy complications. Impaired placenta function can cause preeclampsia and leads to fetal growth restriction due to hypoxia. Presence of hypoxia leads to oxidative stress due to an imbalance between reactive oxygen species and antioxidants, thereby causing damage to proteins, lipids and DNA. In the placenta, signs of morphological adaptation in response to hypoxia can be found. Different placental lesions like maternal or fetal vascular malperfusion or chronic villitis lead to a decreased exchange of oxygen between the mother and the fetus. Clinically, several biomarkers indicative for oxidative stress, e.g. malondialdehyde and reduced levels of free thiols are found. This review aims to give an overview of the causes and (potential) role of placental oxidative stress in the development of placental parenchymal pathology and its clinical consequences. Also, therapeutic options aiming at prevention or treatment of hypoxia of the placenta and fetus are described., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Differentiation of first trimester human placental cytotrophoblast (CTB) from an anchorage-dependent epithelial phenotype into the mesenchymal-like invasive extravillous trophoblast (EVT) is crucial in the development of the maternal-fetal interface. We showed previously that differentiation of first trimester CTB to EVT involves an epithelial-mesenchymal transition (EMT). Here we compare the epithelial-mesenchymal characteristics of CTB and EVT derived from normal third trimester placenta or placenta previa versus abnormally invasive placenta (AIP). CTB and EVT were isolated from normal term placenta or placenta previa following Caesarean section and EVT from AIP following Caesarean hysterectomy. Cell identity was validated by measurement of cytokeratin-7 and HLA-G. Comparing normal term CTB with EVT from normal term placenta or placenta previa for differential expression analysis of genes associated with the EMT showed changes in >70% of the genes probed. While demonstrating a mesenchymal phenotype relative to CTB, many of the gene expression changes in third trimester EVT were reduced relative to the first trimester EVT. We suggest that third trimester EVT are in a more constrained, metastable state compared to first trimester equivalents. By contrast, EVT from AIP demonstrate characteristics that are more mesenchymal than normal third trimester EVT, placing them closer to first trimester EVT on the EMT spectrum, consistent with a more invasive phenotype.

Background: Placental dysfunction is related to many pregnancy complications, but collecting placental specimens for investigation in large scale epidemiologic studies is often infeasible. Standard procedures involving immediate collection after birth and snap freezing are often cost prohibitive. We aimed to collect pilot data regarding the feasibility and precision of a simpler approach, the collection of tissue samples following 24 hours of refrigeration of whole placentae at 4°C, as compared to the "gold standard" of snap freezing excised tissue within 40 minutes of delivery for the assessment of inflammatory cytokines., Methods: Placentae were collected from 12 women after delivering live-born singleton babies via uncomplicated vaginal delivery. Two placentae were utilized to establish laboratory tissue processing and assay protocols. The other 10 placentae were utilized in a comparison of three tissue collection conditions. Specifically, key inflammatory cytokines were measured in 3 sections, representing three collection conditions. Sections 1 (full thickness) and 2 (excised prior to freezing) were obtained within 40 minutes of delivery and snap frozen in liquid nitrogen, and section 3 (full thickness) was obtained after refrigerating the placenta at 4°C for 24 hours., Results: IL-6, IL-10, and IL-8 all had comparable concentrations and variability overall in all three section types. Levels of tumor necrosis factor alpha (TNF-α) were too low among samples to reliably measure using immunoassay., Conclusions: Refrigeration of placentae prior to processing does not appear to compromise detection of these cytokines for purposes of large scale studies. These findings provide a framework and preliminary data for the study of inflammatory cytokines within the placenta in large scale and/or resource-limited settings.

Exosomes (30- to 150-nm particles), originating from multivesicular bodies by the invagination of the endosomal membrane, are communication channels between cells. Exosomes are released by various cell types and cargo proteins, lipids, and nucleic acids reflecting the physiologic status of their cells of origin and cause functional changes in recipient cells, which are likely dependent on their quantity and/or cargo contents. Recently, placental exosomes, produced by various placental cell types, have been isolated from maternal blood using the placental protein-specific marker, placental alkaline phosphatase (PLAP). PLAP-positive exosomes are seen in maternal blood as early as the first trimester of pregnancy and increase as gestation progresses, with maximum numbers seen at term. Although the functional relevance of placental exosomes is still under investigation, several studies have linked placental exosomes changes (quantity and cargo) reflecting placental dysfunctions associated with adverse pregnancy events. As placental exosomes can be isolated from maternal blood, they are liquid biopsies reflecting placental functions. Hence, they are useful as biomarkers of placental functions and dysfunctions obtainable through non-invasive approaches. This review summarizes the biogenesis, release, and functions of exosomes and specifically expounds the role of placental-specific exosomes and their significance associated with pregnancy complications., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Aim: MicroRNAs (miRs) play an essential role in the modulation of trophoblast function. We explored miR-320a expression in the human placenta. In addition, we report the promising effect and target functional loop of miR-320a in trophoblasts., Methods: MiR-320a expression was investigated in both pre-eclamptic and healthy placenta tissues by quantitative real time-polymerase chain reaction to determine how miR-320a affected invasion, proliferation and migration in trophoblasts. A lipopolysaccharide (LPS) model was established in trophoblasts to reveal how LPS supplementation stimulated miR-320a expression. Western blot was applied to measure protein expression, which was involved in pathways modulated by miR-320a in pre-eclamptic placentas., Results: MiR-320a expression was enhanced in the placental specimens of pre-eclamptic patients. Excessive miR-320a expression remarkably suppressed trophoblast invasion but did not affect migration or proliferation. However, transfection with miR-320a inhibitor reinforced trophoblast invasion in vitro. Luciferase assays verified that estrogen-related receptor-gamma (ERRγ) served as a direct target of miR-320a. Quantitative real-time polymerase chain reaction and Western blot demonstrated that excessive miR-320a expression downregulated ERRγ transcription and translation. Additionally, LPS supplementation showed excessive miR-320a expression and ERRγ downregulation. Impaired ERRγ and enhanced miR-320a expression occurred in PE placentas compared to controls. Pearson correlation and linear regression analysis revealed that miR-320a expression was negatively related to ERRγ expression in normal and pre-eclamptic placentas., Conclusions: These findings indicate that miR-320a overexpression causes anomalous placentation by targeting ERRγ. Our research reveals the promising effect of miR-320a and the ERRγ functional loop on placentation., (© 2018 Japan Society of Obstetrics and Gynecology.)

Introduction: Women with a history of placenta-related pregnancy complications, such as preeclampsia, intrauterine growth restriction or preterm delivery, have an increased risk for recurrence of such complications. This recurrence is likely the result of underlying endothelial dysfunction that leads to abnormal placentation, especially in complications with an early onset. This study provides an overview of biomarkers of placental development and function in pregnancies from women with a history of placenta-related complications., Material and Methods: A systematic literature search was conducted limited to human studies and including keywords related to a history of placenta-related complications and markers of placental development and function. Two independent reviewers assessed eligibility and quality of 1553 retrieved unique articles., Results: Five articles reporting on placental development and function in women with an obstetric history of preeclampsia (n = 3), intrauterine growth restriction (n = 1) and preterm delivery (n = 2) were eligible for quality assessment. We identified associations between a history of preeclampsia and abnormal placental histological findings at term in the current pregnancy, but found contradictory results regarding presence of uterine artery notching. In women with a history of very preterm delivery (<32 weeks), one study showed associations with abnormal placental histology., Conclusion: Literature on the association between a history of placenta-related complications and placental development and function in subsequent pregnancies is scarce and studies are heterogeneous. However, literature shows that placenta-related pregnancy complications are associated with subsequent placental histology., (© 2017 Nordic Federation of Societies of Obstetrics and Gynecology.)

Lack of blood flow and aberrant levels of oxygenation in placentas are recurrent in pregnancy diseases, such as preeclampsia. These alterations generate situations of hypoxia and hypoxia/reoxygenation (H/R) and consequent oxidative stress, increased cell death, and inflammation in trophoblasts. The models used to understand the effects of hypoxia and H/R on trophoblasts require a rather big structure. This chapter describes the details of a suitable and reasonable approach with hypoxia chambers to expose human placental trophoblasts to variable conditions of oxygenation.

Aim: Homeostasis model assessment for insulin resistance (HOMA-IR) was measured during pregnancy to analyze placental weight and efficiency in relation to maternal insulin resistance., Methods: A retrospective study of 510 pregnant women (130 with gestational diabetes mellitus [GDM], 380 with normal glucose tolerance) was conducted. We reviewed the patients' demographic data (age, parity, pre-pregnancy body mass index [BMI]) and perinatal outcomes (birth weight, placental weight, BMI at delivery, maternal weight gain, HOMA-IR). The birth weight to placental weight (B/P) ratio was calculated for placental efficiency. The subjects were categorized by BMI at delivery, and maternal, neonatal and placental characteristics were compared between the groups to investigate the determinants of placental weight and B/P ratios., Results: Obesity was significantly associated with heavier placental weight and lower B/P ratios. The presence of GDM did not affect placental weight, whereas the B/P ratios in women with GDM were significantly lower than in women with normal glucose tolerance. HOMA-IR was positively correlated with placental weight (ρ = 0.217, P < 0.001) and negatively with B/P ratio (ρ = -0.181, P < 0.001)., Conclusions: Increased maternal insulin resistance promoted placental growth and inhibited placental efficiency. Maternal insulin resistance may be one of the pathophysiological conditions responsible for altered placental size and function in pregnancies with obesity and GDM., (© 2017 Japan Society of Obstetrics and Gynecology.)

Preeclampsia is a major pregnancy complication associated with poor placental perfusion and placental hypoxia. Systemic and placental inflammation and elevated placental secretion of the antiangiogenic factors sFlt-1 (soluble fms-like tyrosine kinase 1) and sEng (soluble endoglin) are hallmarks of preeclampsia, causing endothelial dysfunction and multiorgan injury. A molecule that links placental hypoxia, inflammation, and antiangiogenic factor release has not been described. ATF3 (activating transcription factor 3) is highly expressed in placenta. We assessed whether placental ATF3 is dysregulated in preterm preeclampsia, is altered by hypoxia, and regulates proinflammatory cytokine and antiangiogenic factor production. ATF3 mRNA and protein expression was significantly reduced in preterm preeclamptic placentas compared with gestation-matched controls. Hypoxia reduced ATF3 expression in primary cytotrophoblast and placental explants. Silencing ATF3 in primary cytotrophoblast increased proinflammatory cytokine (IL-6 [interleukin 6], TNF-α [tumor necrosis factor α]) and NF-κB (nuclear factor κB) expression. In silico analysis identified an ATF3-binding site in the promoter of Flt-1 (the transcript from which sFlt-1 is produced). Silencing ATF3 increased sFlt-1 and sEng secretion from primary cytotrophoblast possibly by increasing Rab11a and Arf1, cargo proteins that facilitate exosomal release of sFlt-1. ATF3 knockout mice did not have a preeclampsia phenotype, suggesting that these pathways may be specific to humans (preeclampsia is a uniquely human condition). To conclude, we have shown that ATF3 is decreased in preeclamptic placentas and that this decrease is likely to occur after prolonged hypoxia. We show that ATF3 is a regulator of placental proinflammatory cytokines and antiangiogenic factors sFlt-1 and sEng. Therefore, reduced ATF3 may be centrally involved in the pathology of preeclampsia., (© 2017 American Heart Association, Inc.)

Receptor activity-modifying protein 2 (Ramp2) is a single-pass transmembrane protein that heterodimerizes with several family B G-protein coupled receptors to alter their function. Ramp2 has been primarily characterized in association with calcitonin receptor-like receptor (Calcrl, CLR), forming the canonical receptor complex for the endocrine peptide adrenomedullin (Adm, AM). However, we previously demonstrated that Ramp2+/- female mice display a constellation of endocrine-related phenotypes that are distinct from those of Adm+/- and Calcrl+/- mice, implying that RAMP2 has physiological functions beyond its canonical complex. Here, we localize Ramp2 expression in the mouse placenta, finding that Ramp2 is robustly expressed in the fetal labyrinth layer, and then characterize the effects of loss of Ramp2 on placental development. Consistent with the expression pattern of Ramp2 in the placenta, Ramp2-/- placentas have a thinner labyrinth layer with significantly fewer trophoblast cells secondary to a reduction in trophoblast proliferation. We also find that absence of Ramp2 leads to failed spiral artery remodeling unaccompanied by changes in the uterine natural killer cell population. Furthermore, we assess changes in gene expression of other RAMP2-associated G-protein coupled receptors (GPCRs), concluding that Ramp2 loss decreases parathyroid hormone 1 receptor (Pthr1) expression and causes a blunted response to systemic parathyroid hormone (PTH) administration in mice. Ultimately, these studies provide in vivo evidence of a role for RAMP2 in placental development distinct from the RAMP2-CLR/AM signaling paradigm and identify additional pathways underlying the endocrine and fertility defects of the previously characterized Ramp2 heterozygous adult females.

Nutrient sulfate has numerous roles in mammalian physiology and is essential for healthy fetal growth and development. The fetus has limited capacity to generate sulfate and relies on sulfate supplied from the maternal circulation via placental sulfate transporters. The placenta also has a high sulfate requirement for numerous molecular and cellular functions, including sulfate conjugation (sulfonation) to estrogen and thyroid hormone which leads to their inactivation. Accordingly, the ratio of sulfonated (inactive) to unconjugated (active) hormones modulates endocrine function in fetal, placental and maternal tissues. During pregnancy, there is a marked increase in the expression of genes involved in transport and generation of sulfate in the mouse placenta, in line with increasing fetal and placental demands for sulfate. The maternal circulation also provides a vital reservoir of sulfate for the placenta and fetus, with maternal circulating sulfate levels increasing by 2-fold from mid-gestation. However, despite evidence from animal studies showing the requirement of maternal sulfate supply for placental and fetal physiology, there are no routine clinical measurements of sulfate or consideration of dietary sulfate intake in pregnant women. This is also relevant to certain xenobiotics or pharmacological drugs which when taken by the mother use significant quantities of circulating sulfate for detoxification and clearance, and thereby have the potential to decrease sulfonation capacity in the placenta and fetus. This article will review the physiological adaptations of the placenta for maintaining sulfate homeostasis in the fetus and placenta, with a focus on pathophysiological outcomes in animal models of disturbed sulfate homeostasis., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The integration of a complex network of signalling molecules promotes implantation of the blastocyst and development of the placenta. These processes are crucial for a successful pregnancy and fetal growth and development. The signalling network involves both cell-cell and cell-extracellular matrix communication. The family of secreted glycoprotein ligands, the Wnts, plays a major role in regulating a wide range of biological processes, including embryonic development, cell fate, proliferation, migration, stem cell maintenance, tumour suppression, oncogenesis and tissue homeostasis. Recent studies have provided evidence that Wnt signalling pathways play an important role in reproductive tissues and in early pregnancy events. The focus of this review is to summarise our present knowledge of expression, regulation and function of the Wnt signalling pathways in early pregnancy events of human and other model systems, and its association with pathological conditions. Despite our recent progress, much remains to be learned about Wnt signalling in human reproduction. The advancement of knowledge in this area has applications in the reduction of infertility and the incidence and morbidity of gestational diseases.

Introduction: The labyrinthine zone of the placenta is where exchange of nutrients and waste occurs between maternal and fetal circulations. Proper development of the placental labyrinth is essential for successful growth of the developing fetus and abnormalities in placental development are associated with intrauterine growth restriction (IUGR), preeclampsia and fetal demise. Our previous studies demonstrate that Hectd1 is essential for development of the junctional and labyrinthine zones of the placenta. Here we further characterize labyrinthine zone defects in the Hectd1 mutant placenta., Methods: The structure of the mutant placenta was compared to wildtype littermates using histological methods. The expression of cell type specific markers was examined by immunohistochemistry and in situ hybridization., Results: Hectd1 is expressed in the labyrinthine zone throughout development and the protein is enriched in syncytiotrophoblast layer type I cells (SynT-I) and Sinusoidal Trophoblast Giant cells (S-TGCs) in the mature placenta. Mutation of Hectd1 results in pale placentas with frequent hemorrhages along with gross abnormalities in the structure of the labyrinthine zone including a smaller overall volume and a poorly elaborated fetal vasculature that contain fewer fetal blood cells. Examination of molecular markers of labyrinthine trophoblast cell types reveals increased Dlx3 positive cells and Syna positive SynT-I cells, along with decreased Hand1 and Ctsq positive sinusoidal trophoblast giant cells (S-TGCs)., Discussion: Together these defects indicate that Hectd1 is required for development of the labyrinthine zonethe mouse placenta., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

For an organ that is so critical for life in eutherian mammals, the placenta hardly gets the attention that it deserves. The placenta does a series of remarkable things, including implanting the embryo in the uterus, negotiating with the mother for nutrients but also protecting her health during pregnancy, helping establish normal metabolic and cardiovascular function for life postnatally (developmental programming) and initiating changes that prepare the mother to care for and suckle her young after birth. Different lines of evidence in experimental animals suggest that the development and function of the placenta are adaptable. This means that some of the changes observed in pathological pregnancies may represent attempts to mitigate the impact of fetal growth and development. Key and emerging concepts are reviewed here concerning how we may view the placenta diagnostically and therapeutically in pregnancy complications, focusing on information from experimental studies in mice, sheep and cattle, as well as association studies from humans. Hundreds of different genes have been shown to underlie normal placental development and function, some of which have promise as tractable targets for intervention in pregnancies at risk for poor fetal growth.

Placental villi play pivotal roles in feto-maternal transportation and phospholipids constitute a major part of the villous membrane. We have been developing and optimizing an imaging system based on a matrix-assisted laser desorption/ionization (MALDI)-based mass spectrometer, which provides clear two-dimensional molecular distribution patterns using highly sensitive mass spectrometry from mixtures of ions generated on tissue surfaces. We recently applied this technology to normal human uncomplicated term placentas and detected the specific distribution of sphingomyelin (SM) (d18:1/16:0) in stem villi and phosphatidylcholine (PC) (16:0/20:4) in terminal villi. In the present study, we applied this technology to nine placentas with maternal or fetal complications, and determined whether a relationship existed between these specific distribution patterns of phospholipid molecules and the six representative pathological findings of placentas, i.e., villitis of unknown etiology (VUE), thrombus, atherosis, chorioamnionitis (CAM), immature terminal villi, and multiple branched terminal villi. In two placentas with the first and second largest total number of positive pathological findings, i.e., five and three positive findings, the specific distribution of SM (d18:1/16:0) in stem villi and PC (16:0/20:4) in terminal villi disappeared. The common pathological findings in these two placentas were atherosis, immature terminal villi, and multiple branched terminal villi, suggesting the possible involvement of the underperfusion of maternal blood into the intervillous space. On the other hand, the number of pathological findings were two or less in the seven other placentas, in which no specific relationships were observed between the differential expression patterns of these two phospholipids in stem and terminal villi and the pathological findings of the placentas; however, the specific distribution pattern of SM (d18:1/16:0) in stem villi disappeared in four placentas, while that of PC (16:0/20:4) in terminal villi was preserved. These results suggested that the absence of the specific distribution of PC (16:0/20:4) in terminal villi, possibly in combination with the absence of SM (d18:1/16:0) in stem villi, was linked to placental morphological changes in response to maternal underperfusion of the placenta.

It is increasingly recognized that vitamin D3 (VitD3) has an anti-inflammatory activity. The present study investigated the effects of maternal VitD3 supplementation during pregnancy on LPS-induced placental inflammation and fetal intrauterine growth restriction (IUGR). All pregnant mice except controls were intraperitoneally injected with LPS (100 μg/kg) daily from gestational day (GD)15-17. In VitD3 + LPS group, pregnant mice were orally administered with VitD3 (25 μg/kg) before LPS injection. As expected, maternal LPS exposure caused placental inflammation and fetal IUGR. Interestingly, pretreatment with VitD3 repressed placental inflammation and protected against LPS-induced fetal IUGR. Further analysis showed that pretreatment with VitD3, which activated placental vitamin D receptor (VDR) signaling, specifically suppressed LPS-induced activation of nuclear factor kappa B (NF-κB) and significantly blocked nuclear translocation of NF-κB p65 subunit in trophoblast gaint cells of the labyrinth layer. Conversely, LPS, which activated placental NF-κB signaling, suppressed placental VDR activation and its target gene expression. Moreover, VitD3 reinforced physical interaction between placental VDR and NF-κB p65 subunit. The further study demonstrates that VitD3 inhibits placental NF-κB signaling in VDR-dependent manner. These results provide a mechanistic explanation for VitD3-mediated anti-inflammatory activity. Overall, the present study provides evidence for roles of VDR as a key regulator of placental inflammation.

Introduction: Villitis of unknown etiology (VUE) is associated with fetal growth restriction. However, the underlying mechanisms of villous injury in placentas with VUE are still largely unknown. We aimed to verify whether apoptosis-related factors are increased in VUE placentas. Furthermore, we determined apoptosis of villous cells., Methods: Six placentas with VUE and 3 control placentas were stained using immunohistochemistry with antibodies for CD3, CD4, CD8, CD68, CD163, perforin, granzyme B, granzyme K, and C5b-9. TUNEL assay analysis was also performed with these placentas. The percentage of cells that stained positive, CD163/CD68 ratio, percentage of C5b-9 positive area, and apoptosis index were quantified and compared between the inflammatory lesions of the VUE placentas, non-VUE inflammatory lesions of the VUE placentas, and control placentas., Results: The percentages of CD3, CD4, CD8 CD68, CD163, perforin, and granzyme B positive cells were significantly higher in the inflammatory lesions of the VUE placentas (p < 0.05). The intravillous CD163/CD68 ratio was higher in the inflammatory lesions compared with the non-inflammatory lesion of the VUE placentas (p < 0.05). The percentage of granzyme K-positive cells was not significantly different between the groups. C5b-9 deposition was higher in the inflammatory lesions of the VUE placentas (p < 0.05). TUNEL-positive cells were significantly higher in the inflammatory lesions of the VUE placentas (p < 0.05)., Discussion: To the best of our knowledge, this is the first report to assess villous injury, especially from a viewpoint of villous apoptosis in VUE placentas. An activated perforin/granzyme pathway and C5b-9 are suggested as possible mechanisms of apoptosis., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Introduction: The placenta is a transient organ the functioning of which has health consequences far beyond the embryo/fetus. Understanding the biology of any system (organ, organism, single cell, etc) requires a comprehensive and inclusive approach which embraces all the biomedical disciplines and 'omic' technologies and then integrates information obtained from all of them. Among the latest 'omics' is morphomics. The terms morphome and morphomics have been applied incoherently in biology and biomedicine but, recently, they have been given clear and widescale definitions., Methods: Morphomics is placed in the context of other 'omics' and its pertinent technologies and tools for sampling and quantitation are reviewed. Emphasis is accorded to the importance of random sampling principles in systems biology and the value of combining 3D quantification with alternative imaging techniques to advance knowledge and understanding of the human placental morphome., Results and Conclusions: By analogy to other 'omes', the morphome is the totality of morphological features within a system and morphomics is the systematic study of those structures. Information about structure is required at multiple levels of resolution in order to understand better the processes by which a given system alters with time, experimental treatment or environmental insult. Therefore, morphomics research includes all imaging techniques at all levels of achievable resolution from gross anatomy and medical imaging, via optical and electron microscopy, to molecular characterisation. Quantification is an important element of all 'omics' studies and, because biological systems exist and operate in 3-dimensional (3D) space, precise descriptions of form, content and spatial relationships require the quantification of structure in 3D. These considerations are relevant to future study contributions to the Human Placenta Project., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Introduction: Monoallelic expression of imprinted genes is necessary for placental development and normal fetal growth. Differentially methylated domains (DMDs) largely determine the parental-specific monoallelic expression of imprinted genes. Maternally derived DNA (cytosine-5-) -methyltransferase 1o (DNMT1o) maintains DMDs during the eight-cell stage of development. DNMT1o-deficient mouse placentas have a generalized disruption of genomic imprints. Previous studies have demonstrated that DNMT1o deficiency alters placental morphology and broadens the embryonic weight distribution in late gestation. Lipids are critical for fetal growth. Thus, we assessed the impact of disrupted imprinting on placental lipids., Methods: Lipids were quantified from DNMT1o-deficient mouse placentas and embryos at E17.5 using a modified Folch method. Expression of select genes critical for lipid metabolism was quantified with RT-qPCR. Mitochondrial morphology was assessed by TEM and mitochondrial aconitase and cytoplasmic citrate concentrations quantified. DMD methylation was determined by EpiTYPER., Results: We found that DNMT1o deficiency is associated with increased placental triacylglycerol levels. Neither fetal triacylglycerol concentrations nor expression of select genes that mediate placental lipid transport were different from wild type. Placental triacylglycerol accumulation was associated with impaired beta-oxidation and abnormal citrate metabolism with decreased mitochondrial aconitase activity and increased cytoplasmic citrate concentrations. Loss of methylation at the MEST DMD was strongly associated with placental triacylglycerol accumulation., Discussion: A generalized disruption of genomic imprints leads to triacylglycerol accumulation and abnormal mitochondrial function. This could stem directly from a loss of methylation at a given DMD, such as MEST, or represent a consequence of abnormal placental development., (Copyright © 2015 Elsevier Ltd. All rights reserved.)