Galectin-3 deficiency in pregnancy increases the risk of fetal growth restriction (FGR) via placental insufficiency

Fetal growth restriction induced by maternal gal-3 deficiency is associated with altered gut-placenta axis

Adverse intrauterine conditions may cause fetal growth restriction (FGR), a pregnancy complication frequently linked to perinatal morbidity and mortality. Although many studies have focused on FGR, the pathophysiological processes underlying this disorder are complex and incompletely understood. We have recently determined that galectin-3 (gal-3), a β-galactoside-binding protein, regulates pregnancy-associated processes, including uterine receptibility, maternal vascular adaptation and placentation. Because gal-3 is expressed at both sides of the maternal-fetal interface, we unraveled the contribution of maternal- and paternal-derived gal-3 on fetal-placental development in the prenatal window and its effects on the post-natal period. Deficiency of maternal gal-3 induced maternal gut microbiome dysbiosis, resulting in a sex-specific fetal growth restriction mainly observed in female fetuses and offspring. In addition, poor placental metabolic adaptions (characterized by decreased trophoblast glycogen content and insulin-like growth factor 2 (Igf2) gene hypomethylation) were only associated with a lack of maternal-derived gal-3. Paternal gal-3 deficiency caused compromised vascularization in the placental labyrinth without affecting fetal growth trajectory. Thus, maternal-derived gal-3 may play a key role in fetal-placental development through the gut-placenta axis.

Modulation of galectin-9 mediated responses in monocytes and T-cells by pregnancy-specific glycoprotein 1

Successful pregnancy relies on a coordinated interplay between endocrine, immune, and metabolic processes to sustain fetal growth and development. The orchestration of these processes involves multiple signaling pathways driving cell proliferation, differentiation, angiogenesis, and immune regulation necessary for a healthy pregnancy. Among the molecules supporting placental development and maternal tolerance, the families of pregnancy-specific glycoproteins and galectins are of great interest in reproductive biology. We previously found that PSG1 can bind to galectin-1 (GAL-1). Herein, we characterized the interaction between PSG1 and other members of the galectin family expressed during pregnancy, including galectin-3, -7, -9, and -13 (GAL-3, GAL-7, GAL-9, and GAL-13). We observed that PSG1 binds to GAL-1, -3, and -9, with the highest apparent affinity seen for GAL-9, and that the interaction of PSG1 with GAL-9 is carbohydrate-dependent. We further investigated the ability of PSG1 to regulate GAL-9 responses in human monocytes, a murine macrophage cell line, and T-cells, and determined whether PSG1 binds to both carbohydrate recognition domains of GAL-9. Additionally, we compared the apparent affinity of GAL-9 binding to PSG1 with other known GAL-9 ligands in these cells, Tim-3 and CD44. Lastly, we explored functional conservation between murine and human PSGs by determining that Psg23, a highly expressed member of the murine Psg family, can bind some murine galectins despite differences in amino acid composition and domain structure.

Placental glycosylation senses the anti-angiogenic milieu induced by human sFLT1 during pregnancy

Abnormal placental angiogenesis during gestation resulting from high levels of anti-angiogenic factors, soluble fms-like tyrosine kinase-1 (sFLT1) and soluble endoglin, has been implicated in the progression of preeclampsia (PE). This heterogeneous syndrome (defined by hypertension with or without proteinuria after 20 weeks of pregnancy) remains a major global health burden with long-term consequences for both mothers and child. Previously, we showed that in vivo systemic human (hsFLT1) overexpression led to reduced placental efficiency and PE-like syndrome in mice. Galectins (gal-1, -3 and -9) are critical determinants of vascular adaptation to pregnancy and dysregulation of the galectin-glycan circuits is associated with the development of this life-threatening disease. In this study, we assessed the galectin-glycan networks at the maternal-fetal interface associated with the hsFLT1-induced PE in mice. We observed an increase on the maternal gal-1 expression in the decidua and junctional zone layers of the placenta derived from hs FLT1high pregnancies. In contrast, placental gal-3 and gal-9 expression were not sensitive to the hsFLT1 overexpression. In addition, O- and N-linked glycan expression, poly-LacNAc sequences and terminal sialylation were down-regulated in hsFLT1 high placentas. Thus, the gal-1-glycan axis appear to play an important role counteracting the anti-angiogenic status caused by sFLT1, becoming critical for vascular adaptation at the maternal-fetal interface.

First Trimester Placental Biomarkers for Pregnancy Outcomes

The placenta plays a key role in several adverse obstetrical outcomes, such as preeclampsia, intrauterine growth restriction and gestational diabetes mellitus. The early identification of at-risk pregnancies could significantly improve the management, therapy and prognosis of these pregnancies, especially if these at-risk pregnancies are identified in the first trimester. The aim of this review was to summarize the possible biomarkers that can be used to diagnose early placental dysfunction and, consequently, at-risk pregnancies. We divided the biomarkers into proteins and non-proteins. Among the protein biomarkers, some are already used in clinical practice, such as the sFLT1/PLGF ratio or PAPP-A; others are not yet validated, such as HTRA1, Gal-3 and CD93. In the literature, many studies analyzed the role of several protein biomarkers, but their results are contrasting. On the other hand, some non-protein biomarkers, such as miR-125b, miR-518b and miR-628-3p, seem to be linked to an increased risk of complicated pregnancy. Thus, a first trimester heterogeneous biomarkers panel containing protein and non-protein biomarkers may be more appropriate to identify and discriminate several complications that can affect pregnancies.

Blocking OLFM4/galectin-3 axis in placental polymorphonuclear myeloid-derived suppressor cells triggers intestinal inflammation in newborns

Fetal growth restriction (FGR) is a major cause of premature and low-weight births, which increases the risk of necrotizing enterocolitis (NEC); however, the association remains unclear. We report a close correlation between placental polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) and NEC. Newborns with previous FGR exhibited intestinal inflammation and more severe NEC symptoms than healthy newborns. Placental PMN-MDSCs are vital regulators of fetal development and neonatal gut inflammation. Placental single-cell transcriptomics revealed that PMN-MDSCs populations and olfactomedin-4 gene (Olfm4) expression levels were significantly increased in PMN-MDSCs in later pregnancy compared to those in early pregnancy and non-pregnant females. Female mice lacking Olfm4 in myeloid cells mated with wild-type males showed FGR during pregnancy, with a decreased placental PMN-MDSCs population and expression of growth-promoting factors (GPFs) from placental PMN-MDSCs. Galectin-3 (Gal-3) stimulated the OLFM4-mediated secretion of GPFs by placental PMN-MDSCs. Moreover, GPF regulation via OLFM4 in placental PMN-MDSCs was mediated via hypoxia inducible factor-1α (HIF-1α). Notably, the offspring of mothers lacking Olfm4 exhibited intestinal inflammation and were susceptible to NEC. Additionally, OLFM4 expression decreased in placental PMN-MDSCs from pregnancies with FGR and was negatively correlated with neonatal morbidity. These results revealed that placental PMN-MDSCs contributed to fetal development and ameliorate newborn intestinal inflammation.

Placental expression quantitative trait loci in an East Asian population

Expression quantitative trait loci (eQTL) analysis measures the contribution of genetic variation in gene expression on complex traits. Although this methodology has been used to examine gene regulation in numerous human tissues, eQTL research in solid tissues is relatively lacking. We conducted eQTL analysis on placentas collected from an East Asian population in an effort to identify gene regulatory mechanisms in this tissue. Placentas (n = 102) were collected at the time of cesarean delivery. mRNA was extracted, sequenced with NGS, and compared with matched maternal and fetal DNA arrays performed using maternal and neonatal cord blood. Linear regression modeling was performed using tensorQTL. Fine-mapping along with epigenomic annotation was used to select putative functional variants. We identified 2,703 coding genes that contained at least one eQTL with statistical significance (false discovery rate <0.05). After fine-mapping, we found 108 previously unreported eQTL variants with posterior inclusion probability >0.1. Of these, 19% were located in genomic regions with evidence from public placental epigenome suggesting that they may be functionally relevant. For example, variant rs28379289 located in the placenta-specific regulatory region changes the binding affinity of transcription factor leading to higher expression of LGALS3, which is known to affect placental function. This study expands the knowledge base of regulatory elements within the human placenta and identifies 108 previously unreported placenta eQTL signals, which are listed in our publicly available GMI eQTL database. Further studies are needed to identify and characterize genetic regulatory mechanisms that affect placental function in normal pregnancy and placenta-related diseases.

Genetic Associations of Circulating Cardiovascular Proteins With Gestational Hypertension and Preeclampsia

Importance

Hypertensive disorders of pregnancy (HDPs), including gestational hypertension and preeclampsia, are important contributors to maternal morbidity and mortality worldwide. In addition, women with HDPs face an elevated long-term risk of cardiovascular disease.

Objective

To identify proteins in the circulation associated with HDPs.

Design, Setting, and Participants

Two-sample mendelian randomization (MR) tested the associations of genetic instruments for cardiovascular disease-related proteins with gestational hypertension and preeclampsia. In downstream analyses, a systematic review of observational data was conducted to evaluate the identified proteins' dynamics across gestation in hypertensive vs normotensive pregnancies, and phenome-wide MR analyses were performed to identify potential non-HDP-related effects associated with the prioritized proteins. Genetic association data for cardiovascular disease-related proteins were obtained from the Systematic and Combined Analysis of Olink Proteins (SCALLOP) consortium. Genetic association data for the HDPs were obtained from recent European-ancestry genome-wide association study meta-analyses for gestational hypertension and preeclampsia. Study data were analyzed October 2022 to October 2023.

Exposures

Genetic instruments for 90 candidate proteins implicated in cardiovascular diseases, constructed using cis-protein quantitative trait loci (cis-pQTLs).

Main Outcomes and Measures

Gestational hypertension and preeclampsia.

Results

Genetic association data for cardiovascular disease-related proteins were obtained from 21 758 participants from the SCALLOP consortium. Genetic association data for the HDPs were obtained from 393 238 female individuals (8636 cases and 384 602 controls) for gestational hypertension and 606 903 female individuals (16 032 cases and 590 871 controls) for preeclampsia. Seventy-five of 90 proteins (83.3%) had at least 1 valid cis-pQTL. Of those, 10 proteins (13.3%) were significantly associated with HDPs. Four were robust to sensitivity analyses for gestational hypertension (cluster of differentiation 40, eosinophil cationic protein [ECP], galectin 3, N-terminal pro-brain natriuretic peptide [NT-proBNP]), and 2 were robust for preeclampsia (cystatin B, heat shock protein 27 [HSP27]). Consistent with the MR findings, observational data revealed that lower NT-proBNP (0.76- to 0.88-fold difference vs no HDPs) and higher HSP27 (2.40-fold difference vs no HDPs) levels during the first trimester of pregnancy were associated with increased risk of HDPs, as were higher levels of ECP (1.60-fold difference vs no HDPs). Phenome-wide MR analyses identified 37 unique non-HDP-related protein-disease associations, suggesting potential on-target effects associated with interventions lowering HDP risk through the identified proteins.

Conclusions and Relevance

Study findings suggest genetic associations of 4 cardiovascular disease-related proteins with gestational hypertension and 2 associated with preeclampsia. Future studies are required to test the efficacy of targeting the corresponding pathways to reduce HDP risk.

In utero pulse injection of isotopic amino acids quantifies protein turnover rates during murine fetal development

Protein translational control is critical for ensuring that the fetus develops correctly and that necessary organs and tissues are formed and functional. We developed an in utero method to quantify tissue-specific protein dynamics by monitoring amino acid incorporation into the proteome after pulse injection. Fetuses of pregnant mice were injected with isotopically labeled lysine and arginine via the vitelline vein at various embyonic days, and organs and tissues were harvested. By analyzing the nascent proteome, unique signatures of each tissue were identified by hierarchical clustering. In addition, the quantified proteome-wide turnover rates were calculated between 3.81E-5 and 0.424 h-1. We observed similar protein turnover profiles for analyzed organs (e.g., liver vs. brain); however, their distributions of turnover rates vary significantly. The translational kinetic profiles of developing organs displayed differentially expressed protein pathways and synthesis rates, which correlated with known physiological changes during mouse development.

Effects of Gestational Arsenic Exposures on Placental and Fetal Development in Mice: The Role of Cyr61 m6A

BACKGROUND

Several epidemiological investigations demonstrated that maternal arsenic (As) exposure elevated risk of fetal growth restriction (FGR), but the mechanism remains unclear.

OBJECTIVES

This study aimed to investigate the effects of gestational As exposure on placental and fetal development and its underlying mechanism.

METHODS

Dams were exposed to 0.15, 1.5, and 15 mg / L NaAsO 2 throughout pregnancy via drinking water. Sizes of fetuses and placentas, placental histopathology, and glycogen content were measured. Placental RNA sequencing was conducted. Human trophoblasts were exposed to NaAsO 2 (2 μ M ) to establish an in vitro model of As exposure. The mRNA stability and protein level of genes identified through RNA sequencing were measured. N 6 -Methyladenosine (m 6 A ) modification was detected by methylated RNA immunoprecipitation-quantitative real-time polymerase chain reason (qPCR). The binding ability of insulin-like growth factor 2 binding protein 2 to the gene of interest was detected by RNA-binding protein immunoprecipitation-qPCR. Intracellular S-adenosylmethionine (SAM) and methyltransferase activity were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and colorimetry, respectively. In vitro As + 3 methyltransferase (As3MT) knockdown or SAM supplementation and in vivo folic acid (FA) supplementation were used to evaluate the protective effect. A case-control study verified the findings.

RESULTS

Sizes of fetuses (exposed to 1.5 and 15 mg / L NaAsO 2 ) and placentas (exposed to 15 mg / L NaAsO 2 ) were lower in As-exposed mice. More glycogen + trophoblasts accumulated and the expression of markers of interstitial invasion was lower in the 15 mg / L NaAsO 2 -exposed mouse group in comparison with control. Placental RNA sequencing identified cysteine-rich angiogenic inducer 61 (Cyr61) as a candidate gene of interest. Mechanistically, mice and cells exposed to As had lower protein expression of CYR61, and this was attributed to a lower incidence of Cyr61 m 6 A . Furthermore, cells exposed to As had lower methyltransferase activity, suggesting that this could be the mechanism by which Cyr61 m 6 A was affected. Depletion of intracellular SAM, a cofactor for m 6 A methyltransferase catalytic domain, partially contributed to As-induced methyltransferase activity reduction. Either As3MT knockdown or SAM supplementation attenuated As-induced Cyr61 m 6 A down-regulation. In mice, FA supplementation rescued As-induced defective trophoblastic invasion and FGR. In humans, a negative correlation between maternal urinary As and plasma CYR61 was observed in infants who were small for gestational age.

DISCUSSION

Using in vitro and in vivo models, we found that intracellular SAM depletion-mediated Cyr61 m 6 A down-regulation partially contributed to As-induced defective trophoblastic invasion and FGR. https://doi.org/10.1289/EHP12207.

Elevated galectin-3 levels detected in women with hyperglycemia during early and mid-pregnancy antagonizes high glucose - induced trophoblast cells apoptosis via galectin-3/foxc1 pathway

OBJECTIVE

This study was to evaluate plasma galectin-3 levels from early pregnancy to delivery and explore the effects of galectin-3 on the function of trophoblast cells under high glucose exposure.

METHODS

The plasma galectin-3 levels were quantified by enzyme-linked immunosorbent assay (ELISA) in the China National Birth Cohort (CNBC) at Peking University First Hospital, and the underlying signaling pathway was identified by protein-protein interaction (PPI) analysis, gene set enrichment analysis (GSEA), quantitative PCR (qPCR), western blotting, small interfering RNA (siRNA) transfections, and flow cytometry.

RESULTS

Significantly higher galectin-3 levels were found in patients with gestational diabetes mellitus (GDM group; n = 77) during the first and second trimesters than that in healthy pregnant women (HP group; n = 113) (P < 0.05). No significant differences in plasma galectin-3 levels were detected between GDM and HP groups in maternal third-trimester blood and cord blood. PPI analysis suggested potential interactions between galectin-3 and foxc1. The findings of GSEA showed that galectin-3 was involved in the cytochrome P450-related and complement-related pathways, and foxc1 was associated with type I diabetes mellitus. Additionally, high glucose (25 mM) significantly increased the expression levels of galectin-3 and foxc1 and induced apoptosis in HTR-8/SVneo cells. Further in vitro experiments showed that galectin-3/foxc1 pathway could protect HTR-8/SVneo cells against high glucose - induced apoptosis.

CONCLUSION

Future studies were required to validate whether plasma galectin-3 might become a potential biomarker for hyperglycemia during pregnancy. Elevated galectin-3 levels might be a vital protective mechanism among those exposed to hyperglycemia during pregnancy.

Dietary Folic Acid Supplementation Attenuates Maternal High-Fat Diet-Induced Fetal Intrauterine Growth Retarded via Ameliorating Placental Inflammation and Oxidative Stress in Rats

The placenta is particularly susceptible to inflammation and oxidative stress, leading to placental vascular dysfunction and placental insufficiency, which is associated with fetal intrauterine growth restriction (IUGR). It is unknown whether folic acid (FA) supplementation can alleviate high-fat diet-induced IUGR in rats by improving placental function. In this study, pregnant rats were randomized into one of four diet-based groups: (1) control diet (CON), (2) control diet supplemented with FA, (3) high-fat diet (HFD), and (4) high-fat diet supplemented with FA (HFD + FA). Dams were sacrificed at gestation day 18.5 (GD18.5). The results indicated that dietary FA supplementation normalized a maternal HFD-induced decrease in fetal weight. The decrease in placental efficiency, labyrinth zone (LZ) area, blood sinusoid area, vascular density, and the levels of angiogenesis factors induced by a maternal HFD were alleviated by the addition of FA, suggesting that FA supplementation can alleviate placental vascular dysplasia. Furthermore, FA supplementation increased the protein expressions of SIRT1, inhibited NF-κB transcriptional activation, attenuated the levels of NF-κB/downstream pro-inflammatory cytokines, induced Nrf2 activation, and increased downstream target protein expression. In conclusion, we found that dietary FA supplementation during pregnancy could improve maternal HFD-induced IUGR by alleviating placental inflammation and oxidative stress, which may be associated with the regulation of SIRT1 and its mediated NF-κB and Nrf2 signaling pathways.

A unique maternal and placental galectin signature upon SARS-CoV-2 infection suggests galectin-1 as a key alarmin at the maternal-fetal interface

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic imposed a risk of infection and disease in pregnant women and neonates. Successful pregnancy requires a fine-tuned regulation of the maternal immune system to accommodate the growing fetus and to protect the mother from infection. Galectins, a family of β-galactoside-binding proteins, modulate immune and inflammatory processes and have been recognized as critical factors in reproductive orchestration, including maternal immune adaptation in pregnancy. Pregnancy-specific glycoprotein 1 (PSG1) is a recently identified gal-1 ligand at the maternal-fetal interface, which may facilitate a successful pregnancy. Several studies suggest that galectins are involved in the immune response in SARS-CoV-2-infected patients. However, the galectins and PSG1 signature upon SARS-CoV-2 infection and vaccination during pregnancy remain unclear. In the present study, we examined the maternal circulating levels of galectins (gal-1, gal-3, gal-7, and gal-9) and PSG1 in pregnant women infected with SARS-CoV-2 before vaccination or uninfected women who were vaccinated against SARS-CoV-2 and correlated their expression with different pregnancy parameters. SARS-CoV-2 infection or vaccination during pregnancy provoked an increase in maternal gal-1 circulating levels. On the other hand, levels of PSG1 were only augmented upon SARS-CoV-2 infection. A healthy pregnancy is associated with a positive correlation between gal-1 concentrations and gal-3 or gal-9; however, no correlation was observed between these lectins during SARS-CoV-2 infection. Transcriptome analysis of the placenta showed that gal-1, gal-3, and several PSG and glycoenzymes responsible for the synthesis of gal-1-binding glycotopes (such as linkage-specific N-acetyl-glucosaminyltransferases (MGATs)) are upregulated in pregnant women infected with SARS-CoV-2. Collectively, our findings identify a dynamically regulated "galectin-specific signature" that accompanies the SARS-CoV-2 infection and vaccination in pregnancy, and they highlight a potentially significant role for gal-1 as a key pregnancy protective alarmin during virus infection.

In utero pulse injection of isotopic amino acids quantifies protein turnover rates during murine fetal development

Protein translational control is highly regulated step in the gene expression program during mammalian development that is critical for ensuring that the fetus develops correctly and that all of the necessary organs and tissues are formed and functional. Defects in protein expression during fetal development can lead to severe developmental abnormalities or premature death. Currently, quantitative techniques to monitor protein synthesis rates in a developing fetus (in utero) are limited. Here, we developed a novel in utero stable isotope labeling approach to quantify tissue-specific protein dynamics of the nascent proteome during mouse fetal development. Fetuses of pregnant C57BL/6J mice were injected with isotopically labeled lysine (Lys8) and arginine (Arg10) via the vitelline vein at various gestational days. After treatment, fetal organs/tissues including brain, liver, lung, and heart were harvested for sample preparation and proteomic analysis. We show that the mean incorporation rate for injected amino acids into all organs was 17.50 ± 0.6%. By analyzing the nascent proteome, unique signatures of each tissue were identified by hierarchical clustering. In addition, the quantified proteome-wide turnover rates (kobs) were calculated between 3.81E-5 and 0.424 hour-1. We observed similar protein turnover profiles for analyzed organs (e.g., liver versus brain), however, their distributions of turnover rates vary significantly. The translational kinetic profiles of developing organs displayed differentially expressed protein pathways and synthesis rates which correlated with known physiological changes during mouse development.

Roles of N-linked glycosylation and glycan-binding proteins in placentation: trophoblast infiltration, immunomodulation, angiogenesis, and pathophysiology

Protein N-linked glycosylation is a structurally diverse post-translational modification that stores biological information in a larger order of magnitude than other post-translational modifications such as phosphorylation, ubiquitination and acetylation. This gives N-glycosylated proteins a diverse range of properties and allows glyco-codes (glycan-related information) to be deciphered by glycan-binding proteins (GBPs). The intervillous space of the placenta is richly populated with membrane-bound and secreted glycoproteins. Evidence exists to suggest that altering the structural nature of their N-glycans can impact several trophoblast functions, which include those related to interactions with decidual cells. This review summarizes trophoblast-related activities influenced by N-glycan-GBP recognition, exploring how different subtypes of trophoblasts actively adapt to characteristics of the decidualized endometrium through cell-specific expression of N-glycosylated proteins, and how these cells receive decidua-derived signals via N-glycan-GBP interactions. We highlight work on how changes in N-glycosylation relates to the success of trophoblast infiltration, interactions of immunomodulators, and uterine angiogenesis. We also discuss studies that suggest aberrant N-glycosylation of trophoblasts may contribute to the pathogenesis of pregnancy complications (e.g. pre-eclampsia, early spontaneous miscarriages and hydatidiform mole). We propose that a more in-depth understanding of how N-glycosylation shapes trophoblast phenotype during early pregnancy has the potential to improve our approach to predicting, diagnosing and alleviating poor maternal/fetal outcomes associated with placental dysfunction.

A placenta-on-a-chip model to determine the regulation of FKBPL and galectin-3 in preeclampsia

Preeclampsia is a pregnancy-specific cardiovascular disorder, involving significant maternal endothelial dysfunction. Although inappropriate placentation due to aberrant angiogenesis, inflammation and shallow trophoblast invasion are the root causes of preeclampsia, pathogenic mechanisms are poorly understood, particularly in early pregnancy. Here, we first confirm the abnormal expression of important vascular and inflammatory proteins, FK506-binding protein-like (FKBPL) and galectin-3 (Gal-3), in human plasma and placental tissues from women with preeclampsia and normotensive controls. We then employ a three-dimensional microfluidic placental model incorporating human umbilical vein endothelial cells (HUVECs) and a first trimester trophoblast cell line (ACH-3P) to investigate FKBPL and Gal-3 signaling in inflammatory conditions. In human samples, both circulating (n = 17 controls; n = 30 preeclampsia) and placental (n ≥ 6) FKBPL and Gal-3 levels were increased in preeclampsia compared to controls (plasma: FKBPL, p < 0.0001; Gal-3, p < 0.01; placenta: FKBPL, p < 0.05; Gal-3, p < 0.01), indicative of vascular dysfunction in preeclampsia. In our placenta-on-a-chip model, we show that endothelial cells are critical for trophoblast-mediated migration and that trophoblasts effectively remodel endothelial vascular networks. Inflammatory cytokine tumour necrosis factor-α (10 ng/mL) modulates both FKBPL and Gal-3 signaling in conjunction with trophoblast migration and impairs vascular network formation (p < 0.005). Our placenta-on-a-chip recapitulates aspects of inappropriate placental development and vascular dysfunction in preeclampsia.

Effects of Salvia miltiorrhiza active compounds on placenta-mediated pregnancy complications

Placenta-mediated pregnancy complications (PMPCs), including preeclampsia (PE), fetal growth restriction (FGR), and recurrent spontaneous abortion (RSA), occur in approximately 5% of pregnancies and are caused by abnormal placenta development. The development of effective therapies for PMPCs is still challenging due to the complicated pathogenesis, such as disrupted vascular homeostasis and subsequent abnormal placentation. Synthetic drugs have been recommended for treating PMPCs; however, they tend to cause adverse reactions in the mother and fetus. Salvia miltiorrhiza (S. miltiorrhiza) has potential effects on PMPCs owing to its advantages in treating cardiovascular disorders. S. miltiorrhiza and its active compounds could attenuate the symptoms of PMPCs through anticoagulation, vasodilation, antioxidation, and endothelial protection. Thus, in this review, we summarize the literature and provide comprehensive insights on S. miltiorrhiza and its phytochemical constituents, pharmacological activities, and on PMPCs, which would be valuable to explore promising drugs.

Placental galectins regulate innate and adaptive immune responses in pregnancy

Introduction

Galectins are master regulators of maternal immune responses and placentation in pregnancy. Galectin-13 (gal-13) and galectin-14 (gal-14) are expressed solely by the placenta and contribute to maternal-fetal immune tolerance by inducing the apoptosis of activated T lymphocytes and the polarization of neutrophils toward an immune-regulatory phenotype.Furthermore, their decreased placental expression is associated with pregnancy complications, such as preeclampsia and miscarriage. Yet, our knowledge of the immunoregulatory role of placental galectins is incomplete.

Methods

This study aimed to investigate the effects of recombinant gal-13 and gal-14 on cell viability, apoptosis, and cytokine production of peripheral blood mononuclear cells (PBMCs) and the signaling pathways involved.

Results

Herein, we show that gal-13 and gal-14 bind to the surface of non-activated PBMCs (monocytes, natural killer cells, B cells, and T cells) and increase their viability while decreasing the rate of their apoptosis without promoting cell proliferation. We also demonstrate that gal-13 and gal-14 induce the production of interleukin (IL)-8, IL-10, and interferon-gamma cytokines in a concentration-dependent manner in PBMCs. The parallel activation of Erk1/2, p38, and NF-ĸB signaling evidenced by kinase phosphorylation in PBMCs suggests the involvement of these pathways in the regulation of the galectin-affected immune cell functions.

Discussion

These findings provide further evidence on how placenta-specific galectins assist in the establishment and maintenance of a proper immune environment during a healthy pregnancy.

The Expression of IL-1β Correlates with the Expression of Galectin-3 in the Tissue at the Maternal-Fetal Interface during the Term and Preterm Labor

The inflammatory processes that occur at the maternal−fetal interface are considered one of the factors that are responsible for preterm birth. The pro-inflammatory roles of the Gal-3-induced activation of NLRP3 inflammasome and the consecutive production of IL-1β have been described in several acute and chronic inflammatory diseases, but the role of this inflammatory axis in parturition has not been studied. The aim of this study was to analyze the protein expression of Gal-3, NLRP3, and IL-1β in the decidua, villi, and fetal membranes, and to analyze their mutual correlation and correlation with the clinical parameters of inflammation in preterm birth (PTB) and term birth (TB). The study included 40 women that underwent a preterm birth (gestational age of 25.0−36.6) and histological chorioamnionitis (PTB) and control subjects, 22 women that underwent a term birth (gestational age of 37.0−41.6) without histological chorioamnionitis (TB). An analysis of the tissue sections that were stained with anti- Gal-3, -NLRP3, and -IL-1β antibodies was assessed by three independent investigators. The expression levels of Gal-3 and IL-1β were significantly higher (p < 0.001) in the decidua, villi, and fetal membranes in the PTB group when they compared to those of the TB group, while there was no difference in the expression of NLRP3. A further analysis revealed that there was no correlation between the protein expression of NLRP3 and the expression of Gal-3 and IL-1β, but there was a correlation between the expression of Gal-3 and IL-1β in decidua (R = 0.401; p = 0.008), villi (R = 0.301; p = 0.042) and the fetal membranes (R = 0.428; p = 0.002) in both of the groups, PTB and TB. In addition, the expression of Gal-3 and IL-1β in decidua and the fetal membranes was in correlation with the parameters of inflammation in the maternal and fetal blood (C-reactive protein, leukocyte number, and fibrinogen). The strong correlation between the expression of Gal-3 and IL-1β in the placental and fetal tissues during labor indicates that Gal-3 may participate in the regulation of the inflammatory processes in the placenta, leading to increased production of IL-1β, a cytokine that plays the main role in both term and preterm birth.

Galectins-1, -3 and -9 Are Present in Breast Milk and Have a Role in Early Life Development

Galectins (Gal) are a family of conserved soluble proteins with high affinity for β-galactoside structures. They have been recognized as important proteins for successful pregnancy. However, little is known about their presence in breast milk and their role in early infancy. Gal-1, -3 and -9 concentrations were evaluated by Multiplex immunoassays in mother–infant pairs from the MAMI cohort in maternal plasma (MP) (n = 15) and umbilical cord plasma (UCP) (n = 15) at birth and in breast milk samples (n = 23) at days 7 and 15 postpartum. Data regarding mother and infant characteristics were collected. Gal-9 was present in a lower concentration range than Gal-1 and Gal-3 in plasma, specifically in UCP. A major finding in the current study is that Gal-1, -3 and -9 were detected for the first time in all the transitional breast milk samples and no differences were found when comparing the two breastfeeding time points. Finally, Gal levels were associated with some maternal and infant characteristics, such as gestational age, pregnancy weight gain, maternal diet, the gender, infant growth and infant infections. In conclusion, Gal levels seem to be involved in certain developmental aspects of early life.

Placental galectin-3 is reduced in early-onset preeclampsia

Preeclampsia is a disease of pregnancy responsible for significant maternal and neonatal mortality. Galectin-3 is a β-Galactoside binding protein. This study aimed to characterise galectin-3 in women with preeclampsia and human trophoblast stem cells (hTSCs). Galectin-3 was measured in placental lysates and plasma collected from patients with early-onset preeclampsia (delivered <34 weeks' gestation) and gestation matched controls. Placental galectin-3 protein was significantly reduced in 43 women with early-onset preeclampsia compared to 21 controls. mRNA expression of LGALS3 (galectin-3 encoding gene) was reduced in 29 women with early-onset preeclampsia, compared to 18 controls (p = 0.009). There was no significant difference in plasma galectin-3 protein in 46 women with early-onset preeclampsia compared to 20 controls. In a separate cohort of samples collected at 36 weeks' gestation, circulating galectin-3 was not altered in 23 women who later developed preeclampsia, versus 182 who did not. In syncytialised hTSCs, hypoxia increased mRNA expression of LGALS3 (p = 0.01). Treatment with inflammatory cytokines (TNF-α and IL-6) had no effect on LGALS3 mRNA expression. However, TNF-α treatment caused an increase in mRNA expression of LGALS3BP (galectin-3 binding protein encoding gene) in hTSCs (p = 0.03). This study showed a reduction of galectin-3 in placenta from pregnancies complicated by early-onset preeclampsia. LGALS3 mRNA expression was dysregulated by hypoxia exposure in placental stem cells.

Exploration of fetal growth restriction induced by vitamin D deficiency in rats via Hippo-YAP signaling pathway

INTRODUCTION

Maternal vitamin D deficiency (VDD) is associated with intrauterine growth restriction (IUGR), but the exact mechanism remains unclear. Here we explored the mechanism through which VDD induced IUGR.

METHODS

Female SD rats were fed a control normal diet (VD > 800 IU/Kg) or VDD diet (VD: 0 IU/Kg) for 8 weeks. Then, females were mated with 12-week-old male SD rats, and fetal and placental tissue were collected on the gestational day 13 (GD13) or 18 (GD18) to analyze the effects of VDD on pregnancy outcome and embryonic development. In vitro, the VDR gene of HTR-8/SVneo cells was knocked down to establish VDD model. Then, HTR-8/SVneo cells were treated with the MST1/2 inhibitor XMU-MP-1 or 0.1 μM/L calcitriol for 24 h (h). The mechanism of Hippo-YAP signaling pathway in VDD-induced placental dysplasia was further investigated by western blot, invasion assay, wound healing assay and Hoechst/PI staining.

RESULTS

The IUGR of the pregnant rats in the VDD group was significant, the placental structure and function were damaged, and there was an obvious inflammatory response, accompanied by a significant increase in the level of the transcription co-activator YAP phosphorylation. In vitro, VDD significantly inhibited the migratory and invasive abilities of HTR-8/SVneo cells, accompanied by decreased EMT capacity and increased apoptosis. When intervening with XMU-MP-1 in advance, we found that the effects of VDD were neutralized by Hippo-YAP signaling blocker.

DISCUSSION

Maternal VDD causes placental dysplasia and IUGR, and these abnormal changes may be associated with the activation of Hippo-YAP signaling pathway.

Galectins: Important Regulators in Normal and Pathologic Pregnancies

Galectins (Gal) are characterized by their affinity for galactoside structures on glycoconjugates. This relationship is mediated by carbohydrate recognition domains, which are multifunctional regulators of basic cellular biological processes with high structural similarity among family members. They participate in both innate and adaptive immune responses, as well as in reproductive immunology. Recently, the discovery that galectins are highly expressed at the maternal–fetal interface has garnerd the interest of experts in human reproduction. Galectins are involved in a variety of functions such as maternal–fetal immune tolerance, angiogenesis, trophoblast invasion and placental development and are considered to be important mediators of successful embryo implantation and during pregnancy. Dysregulation of these galectins is associated with abnormal and pathological pregnancies (e.g., preeclampsia, gestational diabetes mellitus, fetal growth restriction, preterm birth). Our work reviews the regulatory mechanisms of galectins in normal and pathological pregnancies and has implications for clinicians in the prevention, diagnosis and treatment of pregnancy-related diseases.

Gestational cholestasis induced intrauterine growth restriction through triggering IRE1α-mediated apoptosis of placental trophoblast cells

Epidemiological and animal experimental studies suggest an association between gestational cholestasis and intrauterine growth restriction (IUGR). Here, we explored the mechanism through which gestational cholestasis induced IUGR. To establish gestational cholestasis model, pregnant mice were subcutaneously injected with 17α-Ethynylestradiol (E2) on gestational day 13 (GD13)-GD17. Some pregnant mice were intraperitoneally injected with 4μ8C on GD13-GD17. The results found that the apoptosis of trophoblast cells was elevated in placentas of mice with gestational cholestasis and in deoxycholic acid (DCA)-treated human trophoblast cell lines and primary mouse trophoblast cells. Correspondingly, the levels of placental cleaved caspase-3 and Bax were increased, while placental Bcl2 level was decreased in mice with gestational cholestasis and in DCA-treated trophoblast cells. Further analysis found that placental IRE1α pathway was activated in mice with gestational cholestasis and in DCA-treated trophoblast cells. Interestingly, 4μ8C, an IRE1α RNase inhibitor, significantly inhibited caspase-3 activity and apoptosis of trophoblast cells in vivo and in vitro. Importantly, 4μ8C rescued gestational cholestasis-induced placental insufficiency and IUGR. Furthermore, a case-control study demonstrated that placental IRE1α and caspase-3 pathways were activated in cholestasis cases. Our results provide evidence that gestational cholestasis induces placental insufficiency and IUGR may be via triggering IRE1α-mediated apoptosis of placental trophoblast cells.

Prediction of Fetal Growth Restriction for Fetal Umbilical Arterial/Venous Blood Flow Index Evaluated by Ultrasonic Doppler under Intelligent Algorithm

The empirical wavelet transform (EWT) algorithm was applied in ultrasound to explore the predictive value for fetal growth restriction (FGR) in fetal arteriovenous indexes. 142 pregnant women who received prenatal ultrasonic examination and delivered were selected. They were classified into control group and FGR group. There were 102 patients with normal pregnancy in the control group, and 40 patients with delayed fetal growth in the FGR group. The extended triple collocation (ETC) algorithm was employed to divide the Fourier spectrum of signals adaptively, and the constructed small filter banks were classified into corresponding intervals. The instantaneous frequency was analyzed, and the arterial blood flow indexes of the two groups were compared. The results showed that the time-frequency analysis method under EWT had lower normalization error and higher accuracy. The inner diameter and cross-sectional area of FGR were remarkably smaller than those of the control group, and the differences were statistically significant (P < 0.05). There were no significant differences in mean blood flow and mean blood velocity between the control group and FGR group (P > 0.05). The arterial blood flow parameters of the systolic flow velocity (VS) and the diastolic flow velocity (VD) in the FGR group were notably lower than those in the control group, and the differences were significant (P < 0.05). In conclusion, the frequency principal component extracted by EWT algorithm was less disturbed by noise, which could accurately and effectively evaluate fetal arteriovenous blood flow indexes and predict FGR.

The Autophagy-Lysosomal Machinery Enhances Cytotrophoblast–Syncytiotrophoblast Fusion Process

Poor placentation is closely related with the etiology of preeclampsia and may impact fetal growth restriction. For placental developmental growth, we have demonstrated that dysregulation of autophagy, a key mechanism to maintain cellular homeostasis, in trophoblasts contributes to the pathophysiology of preeclampsia, a severe pregnancy complication, associated with poor placentation. It remains, however, unknown whether autophagy inhibition affects trophoblast syncytialization. This study evaluated the effect of autophagy in an in vitro syncytialization method using BeWo cells and primary human trophoblasts (PHT). In this study, we observed that autophagic activity decreased in PHT and BeWo cells during syncytialization. This decreased activity was accompanied by downregulation of the transcription factor, TFEB. Next, bafilomycin A1, an inhibitor of autophagy via suppressing V-ATPase in lysosomes, inhibited hCG production, CYP11A1 expression (a marker of differentiation), p21 expression (a senescence marker), and cell fusion in BeWo cells and PHT cells. Finally, LLOMe, an agent inducing lysosomal damage, also inhibited syncytialization and led to TFEB downregulation. Taken together, the autophagy-lysosomal machinery plays an important role in cytotrophoblast fusion, resulting in syncytiotrophoblasts. As autophagy inhibition contributed to the failure of differentiation in cytotrophoblasts, this may result in the poor placentation observed in preeclampsia.

Next generation of immune checkpoint molecules in maternal-fetal immunity

Successful pregnancy is a unique situation requires the maternal immune system to recognize and tolerate a semi-identical fetus and allow normal invasion of trophoblast cells. Although efforts have been made, the deep mechanisms of the maternal-fetal crosstalk have not yet been fully deciphered. Immune checkpoint molecules (ICMs) are a group of negative modulators of the immune response that avoid immune damage. They have been extensively studied in the fields of oncology and transplantation, while the latest evidence suggests that they are closely associated with pregnancy outcomes via multiple inhibitory mechanisms. Although studies have mostly demonstrated the regulatory role of the well-known PD-1, CTLA-4 at the maternal-fetal interface, what is unique about the newly discovered multiple ICMs remains a mystery. Here, we review the latest knowledge on ICMs, focusing on the first generation of checkpoints (PD-1, CTLA-4) and the next generation (Tim-3, Tigit, Lag-3, VISTA) highlighting their immunoregulatory roles in maternal-fetal tolerance and decidual vascular remodeling, and their involvement in pathological pregnancies. The content covers three aspects: the characteristics they possess, the dynamic expression profile of their expression at the maternal-fetal interface, and their involvement in pathological pregnancy. In immunotherapy strategies for pregnancy complications, upregulation of immune checkpoints may play a role. Meanwhile, the impact on pregnancy outcomes when using ICMs in clinical cancer treatment during pregnancy is a topic worth exploring. These may serve as a guide for future basic research and clinical applications of maternal-fetal immunity.

Medawar's PostEra: Galectins Emerged as Key Players During Fetal-Maternal Glycoimmune Adaptation

Lectin-glycan interactions, in particular those mediated by the galectin family, regulate many processes required for a successful pregnancy. Over the past decades, increasing evidence gathered from in vitro and in vivo experiments indicate that members of the galectin family specifically bind to both intracellular and membrane bound carbohydrate ligands regulating angiogenesis, immune-cell adaptations required to tolerate the fetal semi-allograft and mammalian embryogenesis. Therefore, galectins play important roles in fetal development and placentation contributing to maternal and fetal health. This review discusses the expression and role of galectins during the course of pregnancy, with an emphasis on maternal immune adaptions and galectin-glycan interactions uncovered in the recent years. In addition, we summarize the galectin fingerprints associated with pathological gestation with particular focus on preeclampsia.

miR-6769b-5p targets CCND-1 to regulate proliferation in cadmium-treated placental trophoblasts: Association with the impairment of fetal growth

Environmental cadmium (Cd) is positively associated with placental impairment and fetal growth retardation. Nevertheless, its potential mechanisms remain unclear. microRNAs (miRNAs) are known to influence placental development and fetal growth. This work was aimed to determine which miRNAs are involved in Cd-impaired placental and fetal development based on the mRNA and miRNA expression profiles analysis. As a result, gestational Cd exposure deceased fetal and placental weight, and reduced the protein level of PCNA in human and mouse placentae. Furthermore, the results of mRNA microarray showed that Cd-downregulated mRNAs were predictively correlated with several biological processes, including cell proliferation, differentiation and motility. In addition, the results of miRNA microarray and qPCR assay demonstrated that Cd significantly increased the level of miR-6769b-5p, miR-146b-5p and miR-452-5p. Integrated analysis of Cd-upregulated miRNAs predicted target genes and Cd-downregulated mRNAs found that overlapping mRNAs, such as CCND1, CDK13, RINT1 and CDC26 were also significantly associated with cell proliferation. Further experiments showed that miR-6769b-5p inhibitor, but not miR-146b-5p and miR-452-5p, markedly reversed Cd-downregulated the expression of proliferation-related mRNAs, and thereby restored Cd-decreased the proteins level of CCND1 and PCNA in human placental trophoblasts. Dual luciferase reporter assay further revealed that miR-6769b-5p directly targets CCND1. Finally, the case-control study demonstrated that increased miR-6769b-5p level and impaired cell proliferation were observed in small-for-gestational-age human placentae. In conclusion, miR-6769b-5p targets CCND-1 to regulate proliferation in Cd-treated placental trophoblasts, which is associated with the impairment of fetal growth. Our findings imply that placental miR-6769b-5p may be used as an epigenetic marker for environmental pollutants-caused fetal growth restriction and its late-onset chronic diseases.

Galectins in Early Pregnancy and Pregnancy-Associated Pathologies

Galectins are a family of conserved soluble proteins defined by an affinity for β-galactoside structures present on various glycoconjugates. Over the past few decades, galectins have been recognized as important factors for successful implantation and maintenance of pregnancy. An increasing number of studies have demonstrated their involvement in trophoblast cell function and placental development. In addition, several lines of evidence suggest their important roles in feto-maternal immune tolerance regulation and angiogenesis. Changed or dysregulated galectin expression is also described in pregnancy-related disorders. Although the data regarding galectins' clinical relevance are still at an early stage, evidence suggests that some galectin family members are promising candidates for better understanding pregnancy-related pathologies, as well as predicting biomarkers. In this review, we aim to summarize current knowledge of galectins in early pregnancy as well as in pregnancy-related pathologies.

Expression of the alternative splicing regulator Rbfox2 during placental development is differentially regulated in preeclampsia mouse models

PROBLEM

Proper placental development is pivotal to ensure healthy pregnancy outcomes. Among the multiple cellular mechanisms involved in the orchestration of this process, little is known on the role of alternative splicing events in the modulation of trophoblast cell biology. Here, we evaluated the expression of the alternative splicing regulator Rbfox2 in the pre- and post-placentation period in mouse pregnancies in both healthy and pathological settings.

METHOD OF STUDY

Immunofluorescence analysis of Rbfox2 expression in mouse implantation sites collected during the pre-placentation period (E5-E7) and post-placentation (E13).

RESULTS

We identified a progressive increase of Rbfox2 levels throughout the peri-implantation period with a shift from a cytoplasmatic expression on E5-E6 to a predominantly nuclear expression on E7, together with a prominent expression of this factor in both subcellular compartments of the primitive placenta. Our results further showed that in contrast to healthy gestations, Rbfox2 expression decreased in preeclamptic models during the post-placentation period. Finally, we further demonstrated enhanced expression of Rbfox2 proteins in allogeneic pregnancy compared to syngeneic models.

CONCLUSIONS

Our findings uncover a novel role for Rbfox2-controlled splicing events in the modulation of trophoblast function, with potential implications for the pathogenesis of preeclampsia and other pregnancy complications originated from defective placentation.

Targeted disruption of galectin 3 in mice delays the first wave of spermatogenesis and increases germ cell apoptosis

Galectin 3 is a multifunctional lectin implicated in cellular proliferation, differentiation, adhesion, and apoptosis. This lectin is broadly expressed in testicular somatic cells and germ cells, and is upregulated during testicular development. Since the role of galectin 3 in testicular function remains elusive, we aimed to characterize the role of galectin 3 in testicular physiology. We found that galectin 3 transgenic mice (Lgals3-/-) exhibited significantly decreased testicular weight in adulthood compared to controls. The transgenic mice also exhibited a delay to the first wave of spermatogenesis, a decrease in the number of germ cells at postnatal day 5 (P5) and P15, and defective Sertoli cell maturation. Mechanistically, we found that Insulin-like-3 (a Leydig cell marker) and enzymes involved in steroid biosynthesis were significantly upregulated in adult Lgals3-/- testes. These observations were accompanied by increased serum testosterone levels. To determine the underlying causes of the testicular atrophy, we monitored cellular apoptosis. Indeed, adult Lgals3-/- testicular cells exhibited an elevated apoptosis rate that is likely driven by downregulated Bcl-2 and upregulated Bax and Bak expression, molecules responsible for live/death cell balance. Moreover, the percentage of testicular macrophages within CD45+ cells was decreased in Lgals3-/- mice. These data suggest that galectin 3 regulates spermatogenesis initiation and Sertoli cell maturation in part, by preventing germ cells from undergoing apoptosis and regulating testosterone biosynthesis. Going forward, understanding the role of galectin 3 in testicular physiology will add important insights into the factors governing the development of germ cells and steroidogenesis and delineate novel biomarkers of testicular function.

Insight into the Key Points of Preeclampsia Pathophysiology: Uterine Artery Remodeling and the Role of MicroRNAs

Preeclampsia affects about 3-8% of all pregnancies. It represents a complex and multifaceted syndrome with at least several potential pathways leading to the development of disease. The main dogma in preeclampsia is the two-stage model of disease. Stage 1 (placental stage) takes place in early pregnancy and is thought to be impaired placentation due to inadequate trophoblastic invasion of the maternal spiral arteries that leads to reduced placental perfusion and release of numerous biological factors causing endothelial damage and development of acute maternal syndrome with systemic multiorgan failure (stage 2-the onset of maternal clinical symptoms, maternal stage). Recently, in the light of the vast body of evidence, two-stage model of preeclampsia has been updated with a few novel pathways leading to clinical manifestation in the second part of pregnancy. This paper reviews current state of knowledge about pathophysiology of preeclampsia and places particular focus on the recent advances in understanding of uterine artery remodeling alterations, as well as the role of microRNAs in preeclampsia.

Galectin-Levels Are Elevated in Infants Born Preterm Due to Amniotic Infection and Rapidly Decline in the Neonatal Period

Galectin (gal)-1, -3, and -9 are members of a family of glycan binding proteins that mediate complex interactions between decidual, inflammatory and trophoblast cells modulating several processes during gestation, control of the maternal immune system, and parturition. Their immunomodulatory role in preterm birth and postnatal expression in preterm infants is unknown. We performed a single center prospective study of 170 preterm infants with a gestational age below 35 weeks. Peripheral venous blood samples were collected during the neonatal period and galectin-1, -3, and -9 were determined by ELISA. We noted a strong decline of circulating gal-1 and -3 levels but not gal-9 from birth to day 7 of life. There was an inverse correlation of gal-1 and -3 levels at birth with gestational age. Gal-1 levels were remarkably increased in infants born to amniotic infection syndrome (AIS), which was also observed for gal-9 levels. Infants who developed early-onset sepsis had higher levels of gal-3 at day 1 as compared to unaffected infants. Our observational data imply that galectin-1, -3, and -9 levels are elevated in preterm infants born in an inflammatory milieu such as AIS or EOS. Future studies need to address whether galectins mediate inflammation-induced preterm birth and could therefore be a target for clinical trials.