Galectin-1 and galectin-3 in the trophoblast of the gestational trophoblastic disease

The Role of Helicobacter pylori and Metabolic Syndrome-Related Mast Cell Activation Pathologies and Their Potential Impact on Pregnancy and Neonatal Outcomes

Helicobacter pylori infection, a significant global burden beyond the gastrointestinal tract, has long been implicated in various systemic pathologies. Rising evidence suggests that the bacterium's intricate relationship with the immune system and its potential to induce chronic inflammation impact diverse pathophysiological processes in pregnant women that may in turn affect the incidence of several adverse pregnancy and neonate outcomes. Helicobacter pylori infection, which has been linked to metabolic syndrome and other disorders by provoking pericyte dysfunction, hyperhomocysteinemia, galectin-3, atrial fibrillation, gut dysbiosis, and mast cell activation pathologies, may also contribute to adverse pregnancy and neonatal outcomes. Together with increasing our biological understanding of the individual and collective involvement of Helicobacter pylori infection-related metabolic syndrome and concurrent activation of mast cells in maternal, fetus, and neonatal health outcomes, the present narrative review may foster related research endeavors to offer novel therapeutic approaches and informed clinical practice interventions to mitigate relevant risks of this critical topic among pregnant women and their offspring.

In Vitro Culture Alters Cell Lineage Composition and Cellular Metabolism of Bovine Blastocyst

Profiling bovine blastocyst transcriptome at the single-cell level has enabled us to reveal the first cell lineage segregation, during which the inner cell mass (ICM), trophectoderm (TE), and an undefined population of transitional cells were identified. By comparing the transcriptome of blastocysts derived in vivo (IVV), in vitro from a conventional culture medium (IVC), and in vitro from an optimized reduced nutrient culture medium (IVR), we found a delay of the cell fate commitment to ICM in the IVC and IVR embryos. Developmental potential differences between IVV, IVC, and IVR embryos were mainly contributed by ICM and transitional cells. Pathway analysis of these non-TE cells between groups revealed highly active metabolic and biosynthetic processes, reduced cellular signaling, and reduced transmembrane transport activities in IVC embryos that may lead to reduced developmental potential. IVR embryos had lower activities in metabolic and biosynthetic processes but increased cellular signaling and transmembrane transport, suggesting these cellular mechanisms may contribute to improved blastocyst development compared to IVC embryos. However, the IVR embryos had compromised development compared to IVV embryos with notably over-active transmembrane transport activities that impaired ion homeostasis.

In Vitro Culture Alters Cell Lineage Composition and Cellular Metabolism of Bovine Blastocyst

Profiling transcriptome at single cell level of bovine blastocysts derived in vivo (IVV), in vitro from conventional culture medium (IVC), and reduced nutrient culture medium (IVR) has enabled us to reveal cell lineage segregation, during which forming inner cell mass (ICM), trophectoderm (TE), and an undefined population of transitional cells. Only IVV embryos had well-defined ICM, indicating in vitro culture may delay the first cell fate commitment to ICM. Differences between IVV, IVC and IVR embryos were mainly contributed by ICM and transitional cells. Pathway analysis by using the differentially expressed genes of these non-TE cells between groups pointed to highly active metabolic and biosynthetic processes, with reduced cellular signaling and membrane transport in IVC embryos, which may lead to reduced developmental potential. IVR embryos had lower activities in metabolic and biosynthetic processes, but increased cellular signaling and membrane transport, suggesting these cellular mechanisms may contribute to the improved blastocyst development compared to IVC embryos. However, the IVR embryos had compromised development when compared to IVV embryos with notably over-active membrane transport activities that led to impaired ion homeostasis.

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.

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.

Elevated expression of galectin-3, thioredoxin and thioredoxin interacting protein in preeclampsia

OBJECTIVES

Preeclampsia (PE) is a pregnancy-related syndrome characterized by the onset of hypertension and proteinuria that can lead to end-organ dysfunction. Galectin-3 (Gal-3) is involved in cell growth, differentiation, inflammation and fibrosis. Thioredoxin (TXN) acts as antioxidant enzyme in several cellular processes, regulating inflammation and inhibiting apoptosis. TXNIP is an endogenous inhibitor of TXN. We evaluated changes in the inflammatory response of Gal-3, TXN, and TXNIP at the level of maternal blood, placenta, and umbilical cord blood of women with PE.

STUDY DESIGN

Ten women with PE and 20 with normal pregnancy (NP) were recruited during admission for delivery. Blood samples were obtained from parturients and umbilical cords, and placental tissue for analysis.

RESULTS

Gal-3 and TXNIP mRNA expression were higher in maternal plasma in PE group compared to NP and were lower in cord blood plasma and placentas in the PE group. In the PE group, TXN/TXNIP mRNA ratio was higher in cord blood plasma (2.07) compared to maternal plasma (1.09). TXN/TXNIP placental protein ratio was similar between PE (0.89) and NP (0.79). ELISA demonstrated that Gal-3 levels in maternal serum were significantly higher in the PE vs. the NP group.

CONCLUSIONS

Pro-inflammatory changes were expressed by high Gal-3 and TXNIP mRNA in maternal blood of PE women, but not in their placental and cord blood samples. These findings may imply that the placenta has a role in protecting the fetus from the damages of inflammatory response, which is more common in PE than in NP.

Enhanced expression of Galectin-3 in gestational diabetes

BACKGROUND AND AIMS

Gestational diabetes mellitus (GDM), hyperglycemia diagnosed during pregnancy, is one of the most common medical complications of pregnancy, treated primarily by diet and pharmacotherapy, if indicated. It is well-established that GDM increases the risk of adverse pregnancy outcomes and long-term complications in mothers and infants. Galectin-3 (Gal-3) is important in processes of cell growth, differentiation, inflammation, and fibrosis. We evaluated Gal-3 expression in pregnancies complicated by GDM as a parameter that might explain how GDM influences early onset of future complications.

METHODS AND RESULTS

Forty-four women with GDM and 40 with normal pregnancy (NP) were recruited during delivery admission. Blood samples were obtained from parturients and umbilical cords blood, as well as placental tissue for analysis. Gal-3 mRNA expression was increased in maternal blood samples and placental tissue of women with GDM compared to NP. In GDM, Gal-3 mRNA was decreased in cord blood compared to maternal blood and placental tissue. Gal-3 GDM placental protein expression was increased compared to NP. Immunostaining revealed that Gal-3 is upregulated in GDM placental extravillous trophoblast. ELISA of Gal-3 maternal serum levels between GDM and NP were similar.

CONCLUSION

Gal-3 is strongly expressed at molecular levels (mRNA and protein expression) in GDM maternal blood and placental tissue, and decreased in cord blood. These findings highlight the role of the placenta in protecting the fetus from potential Gal-3 damage. Gal-3 expression at mRNA and protein levels might be influenced by diabetes, even if blood glucose is balanced by medication or diet.

Immune cells in normal pregnancy and gestational trophoblastic diseases

A healthy pregnancy requires the development of maternal-fetal immune tolerance against the semi-allogeneic fetus. The interactions between the trophoblastic cells and the maternal immune cells (p.e., natural killer cells, T cells, macrophages, dendritic cells and B-cells) are important for the development of the maternal-fetal immune tolerance and the placental growth and function. These interactions are mediated by cell to cell contact and secreted molecules such as cytokines, chemokines, angiogenic factors and growth factors. The maternal immune cells are present in normal non-pregnant and pregnant endometrium and there are several lines of evidence based on immunohistochemical and RNA sequencing data that the decidual immune cells and immune-related pathways display alterations in GTD, which may have pathogenetic and clinical significance. The present review focuses on the usefulness of the immunohistochemical analysis which provides multiparametric in situ information regarding the numbers, the immunophenotypes and the immunotopographical distributions of the decidual immune cells in tissue sections from normal pregnancy and GTD. We also discuss the significance of the immunohistochemical information in order to gain insight in the putative mechanisms explaining the alterations of the decidual immune cells in GTD and the potential implications of these alterations in the pathogenesis and the clinical behavior of GTD.

The chimera-type galectin-3 is a positive modulator of trophoblast functions with dysregulated expression in gestational diabetes mellitus

PROBLEM

From conception, a delicate regulation of galectins, a family of carbohydrate-binding proteins, is established to ensure maternal immune tolerance in pregnancy. Though galectin-3 (gal-3), the only chimera-type galectin, is abundantly expressed at the feto-maternal interface; the physiological role of this lectin during pregnancy remains to be fully elucidated and requires further investigation.

METHOD OF STUDY

In this study, we analyzed serum gal-3 levels during the course of healthy gestation. Trophoblast functions were evaluated upon gal-3 exogenous stimulation using trophoblastic cell lines (e.g. , HIPEC65, SGHPL-4, and BeWo cells). Finally, we investigated variations in peripheral gal-3 levels associated with the development of spontaneous abortion and gestational diabetes mellitus (GDM).

RESULTS

Gal-3 circulating levels increased as normal pregnancy progressed. In vitro experiments showed that exogenous gal-3 positively regulated trophoblast functions inducing invasion, tube formation, and fusion. Compared with normal pregnant women, circulating gal-3 levels were significantly decreased in patients who developed GDM.

CONCLUSION

Our results reveal a physiological role for gal-3 during pregnancy, promoting proper trophoblast functions associated with healthy gestation. GDM is associated with a failure to increase circulating gal-3 levels late in gestation. Thus, dysregulation of gal-3 may indicate a contribution of the chimera-type lectin to this adverse pregnancy outcome.

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

Fetal growth restriction (FGR) is the most common pregnancy complication in developed countries. Pregnancies affected by FGR, frequently concur with complications and high risk of neonatal morbidity and mortality. To date, no approved treatment is available for pregnant women affected with FGR. The objective of this study was to investigate the contribution of galectin-3 (gal-3), a β-galactoside binding protein involved in pregnancy, placental function and fetal growth. We demonstrated that lack of gal-3 during mouse pregnancy leads to placental dysfunction and drives FGR in the absence of a maternal preeclampsia syndrome. Analysis of gal-3 deficient dams revealed placental inflammation and malperfusion, as well as uterine natural killer cell infiltration with aberrant activation. Our results also show that FGR is associated with a failure to increase maternal circulating gal-3 levels during the second and third trimester in human pregnancies. Placentas from human pregnancies affected by FGR displayed lower gal-3 expression, which correlated with placental dysfunction. These data highlight the importance of gal-3 in the promotion of proper placental function, as its absence leads to placental disease and subsequent FGR.

Glycan characterization of pregnancy-specific glycoprotein 1 and its identification as a novel Galectin-1 ligand

Pregnancy-specific beta 1 glycoprotein (PSG1) is secreted from trophoblast cells of the human placenta in increasing concentrations as pregnancy progresses, becoming one of the most abundant proteins in maternal serum in the third trimester. PSG1 has seven potential N-linked glycosylation sites across its four domains. We carried out glycomic and glycoproteomic studies to characterize the glycan composition of PSG1 purified from serum of pregnant women and identified the presence of complex N-glycans containing poly LacNAc epitopes with α2,3 sialyation at four sites. Using different techniques, we explored whether PSG1 can bind to galectin-1 (Gal-1) as these two proteins were previously shown to participate in processes required for a successful pregnancy. We confirmed that PSG1 binds to Gal-1 in a carbohydrate-dependent manner with an affinity of the interaction of 0.13 μM. In addition, we determined that out of the three N-glycosylation-carrying domains, only the N and A2 domains of recombinant PSG1 interact with Gal-1. Lastly, we observed that the interaction between PSG1 and Gal-1 protects this lectin from oxidative inactivation and that PSG1 competes the ability of Gal-1 to bind to some but not all of its glycoprotein ligands.

The Galectin Family as Molecular Targets: Hopes for Defeating Pancreatic Cancer

Galectins are a family of proteins that bind β-galactose residues through a highly conserved carbohydrate recognition domain. They regulate several important biological functions, including cell proliferation, adhesion, migration, and invasion, and play critical roles during embryonic development and cell differentiation. In adults, different galectin members are expressed depending on the tissue type and can be altered during pathological processes. Numerous reports have shown the involvement of galectins in diseases, mostly inflammation and cancer. Here, we review the state-of-the-art of the role that different galectin family members play in pancreatic cancer. This tumor is predicted to become the second leading cause of cancer-related deaths in the next decade as there is still no effective treatment nor accurate diagnosis for it. We also discuss the possible translation of recent results about galectin expression and functions in pancreatic cancer into clinical interventions (i.e., diagnosis, prediction of prognosis and/or therapy) for this fatal disease.

Pregnancy Galectinology: Insights Into a Complex Network of Glycan Binding Proteins

Galectins are a phylogenetically conserved family of soluble β-galactoside binding proteins, consisting of 15 different types, each with a specific function. Galectins contribute to placentation by regulating trophoblast development, migration, and invasion during early pregnancy. In addition, galectins are critical players regulating maternal immune tolerance to the embedded embryo. Recently, the role of galectins in angiogenesis during decidualization and in placenta formation has gained attention. Altered expression of galectins is associated with abnormal pregnancies and infertility. This review focuses on the role of galectins in pregnancy-associated processes and discusses the relevance of galectin-glycan interactions as potential therapeutic targets in pregnancy disorders.

Human trophoblast requires galectin-3 for cell migration and invasion

Invasive extravillous cytotrophoblast of the human placenta expresses galectins-1, -3, and -8 in vivo and in vitro. This study aimed to investigate the potential role of galectin-3 in cell migration and invasion, using recombinant human galectin-3 (rhgalectin-3), small molecule galectin inhibitor I₄₇, and galectin-3 silencing. HTR-8/SVneo cell migration was stimulated by rhgalectin-3 and reduced by I₄₇, which could be neutralised by rhgalectin-3. Inhibitor specificity and selectivity for the galectins expressed in extravillous trophoblast were validated in solid phase assays using recombinant galectin-1, -3, -8, confirming selectivity for galectin-3. HTR-8/SVneo cell migration and invasion, and invasion by isolated trophoblast cells in primary culture were significantly reduced in the presence of I_47, which could be restored by rhgalectin-3. Upon HTR-8/SVneo cell treatment with galectin-3 siRNA both LGALS3 and galectin-3 protein were dramatically decreased. Silencing of galectin-3 induced significant reduction in cell migration and invasion, which was restored by rhgalectin-3. The influence on known mediators of cell invasion, MMP2 and -9, and integrins α₁, α₅, and β₁ was followed in silenced cells, showing lower levels of MMPs and a large reduction in integrin subunit β₁. These results show that galectin-3 acts as a pro-invasive autocrine/paracrine factor in trophoblast in vitro.

Impact of Galectin-1 on Trophoblast Stem Cell Differentiation and Invasion in In Vitro Implantation Model

Trophoblast stem cells (TSCs) differentiate in an orderly manner, which plays an important role in the process of embryo implantation, placentation, and early pregnancy maintenance. At the maternal-fetal interface, the dialogue is crucial between trophoblast cells and endometrial epithelial cells. Previous studies suggested that galectin-1 (Gal-1) may play an important role in placental development. In this study, we used Ishikawa (IK) cells-TSC coculture model to simulate the maternal-fetal interface and induce the differentiation of TSCs by differentiation media. The messenger RNA level of each cell type markers, fusion markers, and Gal-1 was detected by quantitative reverse transcription polymerase chain reaction during the differentiation of TSCs. Wound healing and transwell invasion assays were used to detect the migration and invasion ability in each group. We found that coculture with IK cells or conditioned media from IK cells could promote the differentiation and invasion of TSCs and increase Gal-1 expression in TSCs. Furthermore, recombinant Gal-1 could also promote the differentiation and invasion of TSCs, suggesting that some of IK cells secretion increase the expression of Gal-1 in TSCs during implantation, which then induced trophoblast differentiation and invasion in vitro. These findings provide significant insights into the biology of embryo-maternal interactions with the importance of Gal-1 in TSCs for the successful establishment and maintenance of pregnancy.

Tissue- and cell-specific localization of galectins, β-galactose-binding animal lectins, and their potential functions in health and disease

Fifteen galectins, β-galactose-binding animal lectins, are known to be distributed throughout the body. We herein summarize current knowledge on the tissue- and cell-specific localization of galectins and their potential functions in health and disease. Galectin-3 is widely distributed in epithelia, including the simple columnar epithelium in the gut, stratified squamous epithelium in the gut and skin, and transitional epithelium and several regions in nephrons in the urinary tract. Galectin-2 and galectin-4/6 are gut-specific, while galectin-7 is found in the stratified squamous epithelium in the gut and skin. The reproductive tract mainly contains galectin-1 and galectin-3, and their expression markedly changes during the estrous/menstrual cycle. The galectin subtype expressed in the corpus luteum (CL) changes in association with luteal function. The CL of women and cows displays a "galectin switch" with coordinated changes in the major galectin subtype and its ligand glycoconjugate structure. Macrophages express galectin-3, which may be involved in phagocytotic activity. Lymphoid tissues contain galectin-3-positive macrophages, which are not always stained with the macrophage marker, F4/80. Subsets of neurons in the brain and dorsal root ganglion express galectin-1 and galectin-3, which may contribute to the regeneration of damaged axons, stem cell differentiation, and pain control. The subtype-specific contribution of galectins to implantation, fibrosis, and diabetes are also discussed. The function of galectins may differ depending on the tissues or cells in which they act. The ligand glycoconjugate structures mediated by glycosyltransferases including MGAT5, ST6GAL1, and C2GnT are important for revealing the functions of galectins in healthy and disease states.

Prototype and Chimera-Type Galectins in Placentas with Spontaneous and Recurrent Miscarriages

Galectins are galactose binding proteins and, in addition, factors for a wide range of pathologies in pregnancy. We have analyzed the expression of prototype (gal-1, -2, -7, -10) and chimera-type (gal-3) galectins in the placenta in cases of spontaneous abortions (SPA) and recurrent abortions (RA) in the first trimester. Fifteen placental samples from healthy pregnancies were used as a control group. Nine placentas were examined for spontaneous abortions, and 12 placentas for recurrent abortions. For differentiation and evaluation of different cell types of galectin-expression in the decidua, immunofluorescence was used. For all investigated prototype galectins (gal-1, -2, -7, -10) in SPA and RA placenta trophoblast cells the expression is significantly decreased. In the decidua/extravillous trophoblast only gal-2 expression was significantly lowered, which could be connected to its role in angiogenesis. In trophoblasts in first-trimester placentas and in cases of SPA and RA, prototype galectins are altered in the same way. We suspect prototype galectins have a similar function in placental tissue because of their common biochemical structure. Expression of galectin 3 as a chimera type galectin was not found to be significantly altered in abortive placentas.

Gal-1 silenced trophoblast tumor cells (BeWo) show decreased syncytium formation and different miRNA production compared to non-target silenced BeWo cells

Galectin-1 (gal-1), a member of the mammalian β-galactoside-binding proteins, exerts biological effects by recognition of glycan ligands, including those involved in cell adhesion and growth regulation. In previous studies, we demonstrated that gal-1 induces cell differentiation processes on the membrane of choriocarcinoma cells BeWo, including the receptor tyrosine kinases (RTKs) REarranged during Transfection (RET), Janus Kinase 2 (JAK2) and Vascular endothelial growth factor receptor 3 (VEGFR3). Furthermore, Mitogen-Activated Protein Kinases (MAPK) and serine/threonine kinases were phosphorylated by gal-1. In addition, gal-1 in trophoblast cells in vitro induced syncytium formation especially after concentration dependent stimulation of the cells with this galectin. This is in contrast to MAPK-inhibitor U0126 that reduced syncytium formation of BeWo cells. The aim of this study was to analyze the syncytium formation abilities of BeWo cells that were gal-1 silenced. We found a significantly reduced syncytium formation rate in gal-1 silenced BeWo cells. In addition, these cells show a different miRNA expression profile. In summary, we found that gal-1 is a major trigger for fusion processes in BeWo cells. This function is accompanied by different regulation of miRNA synthesis in the BeWo cell culture model.

Galectins: Double-edged Swords in the Cross-roads of Pregnancy Complications and Female Reproductive Tract Inflammation and Neoplasia

Galectins are an evolutionarily ancient and widely expressed family of lectins that have unique glycan-binding characteristics. They are pleiotropic regulators of key biological processes, such as cell growth, proliferation, differentiation, apoptosis, signal transduction, and pre-mRNA splicing, as well as homo- and heterotypic cell-cell and cell-extracellular matrix interactions. Galectins are also pivotal in immune responses since they regulate host-pathogen interactions, innate and adaptive immune responses, acute and chronic inflammation, and immune tolerance. Some galectins are also central to the regulation of angiogenesis, cell migration and invasion. Expression and functional data provide convincing evidence that, due to these functions, galectins play key roles in shared and unique pathways of normal embryonic and placental development as well as oncodevelopmental processes in tumorigenesis. Therefore, galectins may sometimes act as double-edged swords since they have beneficial but also harmful effects for the organism. Recent advances facilitate the use of galectins as biomarkers in obstetrical syndromes and in various malignancies, and their therapeutic applications are also under investigation. This review provides a general overview of galectins and a focused review of this lectin subfamily in the context of inflammation, infection and tumors of the female reproductive tract as well as in normal pregnancies and those complicated by the great obstetrical syndromes.

Expression and function of galectins in the endometrium and at the human feto-maternal interface

Galectins are classified as lectins that share structural similarities and bind β-galactosides via a conserved carbohydrate recognition domain. So far 16 out of 19 identified galectins were shown to be present in humans and numerous studies revealed galectins as pivotal modulators of cell death, differentiation and growth. Galectins were highlighted to interact with both the adaptive and innate immune response. In the field of reproductive medicine and placenta research different roles for galectins have been proposed. Several galectins, being abundantly present at the human feto-maternal interphase and endometrium, were hypothesized to significantly contribute to endometrial receptivity and pregnancy physiology. Hence, this review outlines selected aspects of galectin action within endometrial function and at the feto-maternal interphase. Further current knowledge on galectins in reproductive and pregnancy disorders like endometriosis, abortion or preeclampsia is summarized.

Prolactin stimulates cell migration and invasion by human trophoblast in vitro

INTRODUCTION

Prolactin (PRL) is present in endometrium at the time of embryo implantation and throughout pregnancy. Extrapituitary PRL acts as a cytokine in cells expressing PRL receptor (PRLR). So far no specific function has been demonstrated for PRL in the trophoblast of early pregnancy.

METHODS

PRLR in placental tissue and trophoblast cells was shown here immunochemically. The possibility that PRL could influence trophoblast cell migration and invasion was investigated in vitro using isolated cytotrophoblast of the first trimester of pregnancy placental tissue and HTR-8/SVneo cell line. Wound healing cell migration test was performed on HTR-8/SVneo cells, and both cell types were used in Matrigel invasion test.

RESULTS

PRLR is expressed by extravillous cytotrophoblast of the cell column and the placental bed, as well as in isolated cytotrophoblast (CT) and HTR-8/SVneo cells. PRL (at 100 and 1000 ng/ml) stimulated HTR-8/SVneo cell migration and cell invasion in both cell types, which could be blocked by anti-PRLR. Integrins α1 and α5, and galectin-1 (gal-1) were variably increased in PRL treated CT and HTR-8/SVneo cells.

DISCUSSION

To our knowledge this is the first study demonstrating that PRL stimulates trophoblast invasiveness through PRLR, which is accompanied by increased integrins and gal-1, not excluding change in other potential mediators. This finding further supports relevance of PRLR for invasive trophoblast.

CONCLUSION

This report supports a possibility that PRL may have a role in trophoblast invasion in vivo.

Galectin-1 markedly reduces the incidence of resorptions in mice missing immunophilin FKBP52

Progesterone (P(4)) signaling is critical for pregnancy. We previously showed that immunopilin FK506 binding protein (FKBP)52 serves as a cochaperone to optimize progesterone receptor (PR) function in the uterus, and its deficiency leads to P(4) resistance in a pregnancy stage-specific and genetic background-dependent manner in mice. In particular, sc placement of SILASTIC implants carrying P(4) rescued implantation failure in CD1 Fkbp52(-/-) mice, but the resorption rate was substantially high at midgestation due to reduced P(4) responsiveness. Because downstream targets of P(4)-FKBP52-PR signaling in the uterus to support pregnancy are not clearly understood, we performed proteomic analysis using Fkbp52(-/-), PR-deficient (Pgr(-/-)), and wild-type (WT) uteri. We found that the expression of galectin-1 (Gal1), an evolutionarily conserved glycan-binding protein, was significantly down-regulated in both Fkbp52(-/-) and Pgr(-/-) uteri compared with WT uteri. During early gestation, Lgals1, which encodes Gal1, was distinctly expressed in stromal and decidual cells. Lgals1 expression was much lower in d 4 Fkbp52(-/-) uteri compared with WT uteri, and this reduction was reversed by P(4) supplementation. More interestingly, concomitant supplementation of recombinant Gal1 significantly suppressed the high resorption rate and leukocyte infiltration at implantation sites in CD1 Fkbp52(-/-) females carrying P(4) SILASTIC implants. These findings suggest that uterine Gal1 is an important downstream target of P(4)-FKBP52-PR signaling in the uterus to support P(4) responsiveness during pregnancy.

Galectins: guardians of eutherian pregnancy at the maternal-fetal interface

Galectins are multifunctional regulators of fundamental cellular processes. They are also involved in innate and adaptive immune responses, and play a functional role in immune-endocrine crosstalk. Some galectins have attracted attention in the reproductive sciences because they are highly expressed at the maternal-fetal interface, their functional significance in eutherian pregnancies has been documented, and their dysregulated expression is observed in the 'great obstetrical syndromes'. The evolution of these galectins has been linked to the emergence of eutherian mammals. Based on published evidence, galectins expressed at the maternal-fetal interface may serve as important proteins involved in maternal-fetal interactions, and the study of these galectins may facilitate the prediction, prevention, diagnosis, and treatment of pregnancy complications.

Galectin-1 is part of human trophoblast invasion machinery--a functional study in vitro

BACKGROUND

Interactions of glycoconjugates with endogenous galectins, have been long proposed to participate in several reproductive processes including implantation. In human placenta gal-1, gal-3, gal-8, and gal-13 proteins are known to be present. Each of them has been proposed to play multiple functions, but so far no clear picture has emerged. We hypothesized that gal-1 participates in trophoblast invasion, and conducted Matrigel invasion assay using isolated cytotrophoblast from first trimester placenta and HTR-8/SVneo cell line to test it.

METHODS AND FINDINGS

Function blocking anti-gal-1 antibody was employed to assess participation of endogenous gal-1 in cell adhesion, cell invasion of HTR-8/SVneo cells. When gal-1 was blocked in isolated trophoblast cell invasion was reduced to 75% of control (SEM ± 6.3, P<0.001) and to 66% of control (SEM ± 1.7, P<0.001) in HTR-8/SVneo cell line. Increased availability of gal-1, as two molecular forms of recombinant human gal-1 (CS-gal-1 and Ox-gal-1), resulted in increased cell invasion by cytotrophoblast to 151% (SEM ± 16, P<0.01) with 1 ng/ml of CS-gal-1, and to 192% (SEM ± 51, P<0.05) with 1 µg/ml of Ox-gal-1. Stimulation was also observed in HTR-8/SVneo cells, to 317% (SEM ± 58, P<0.001) by CS-gal-1, and to 200% (SEM ± 24, P<0.001) by Ox-gal-1 at 1 µg/ml. Both sets of results confirmed involvement of gal-1 in trophoblast invasion. Galectin profile of isolated cytotrophoblast and HTR-8/SVneo cells was established using RT-PCR and real-time PCR and found to consist of gal-1, gal-3 and gal-8 for both cell types. Only gal-1 was located at the trophoblast cell membrane, as determined by FACS analysis, which is consistent with the results of the functional tests.

CONCLUSION AND SIGNIFICANCE

These findings qualify gal-1 as a member of human trophoblast cell invasion machinery.

CLIC1 protein: a candidate prognostic biomarker for malignant-transformed hydatidiform moles

OBJECTIVES

The purpose of this study was to identify prognostic biomarkers indicating malignant transformation of hydatidiform moles (HMs).

METHODS

Two-dimensional gel electrophoresis-based proteomic approach was used to compare the protein profiles of complete benign moles (3 samples) with those of malignant-transformed moles (3 samples). Matrix-assisted laser desorption/ionization time of flight mass spectrometry was used to identify differentially expressed proteins. Western blot was used to verify the results of 2-dimensional gel electrophoresis, and immunohistology was used to explore the function of these proteins in gestational trophoblastic disease.

RESULTS

Eighteen proteins, deregulated in the malignant-transformed group compared with the benign group (ratio ≥ 2; P < 0.05), were identified. A bioinformatic analysis indicated that most of these 18 proteins were involved in the processes of cell proliferation and cell survival. Among the 18 proteins, chloride intracellular channel protein 1 (CLIC1) was chosen for further study. Our results showed that the levels of CLIC1 expression in choriocarcinoma tissue were higher than in complete HM tissue (P < 0.01). Chloride intracellular channel protein 1 expression was increased in the tissues of malignant-transformed HMs compared with nontransformed HMs (P < 0.01).

CONCLUSION

Our findings suggest that CLIC1 could be a potential new prognostic biomarker for hydatidiform mole that undergoes malignant transformation.

Choriocarcinoma cell line Response to Dexamethasone

Choriocarcinoma cell lines JAr and JEG-3 are model systems for the study of transformed trophoblast. Both cell lines were shown to produce galectin-1, expression of which was increased in choriocarcinoma when compared to the normal trophoblast of pregnancy. In this study the effects of synthetic glucocorticoid dexametha-sone were investigated in both JAr and JEG-3 cell lines by the MTT test, cell based ELISA, and the cell adhesion and migration tests. Viable cell number/cell proliferation of JAr cells was significantly increased after treatment with 0.1 and 1 nmol/L of dexamethasone, while proliferation of JEG-3 cells was significantly increased after treatment in the whole concentration range of dexamethasone (0.1-100 nmol/L). Galectin-1 in JAr cells was modulated by dexamethasone, which mildly, but significantly decreased production at low concentrations (0.1 and 1 nmol/L). In JEG-3 cells production of galectin-1 was significantly decreased only after treatment with 100 nmol/L of dexamethasone. Cell adhesion of JEG-3 was significantly increased in the presence of lactose, an inhibitory sugar for gal-1, while dexamethasone induced decrease of JEG-3 cell migration. These findings have shown that dexamet-hasone may affect proliferation, gal-1 production and cell migration, in a cell line specific manner. These data suggest that glucocorticoid treatmentin vivomight have the potential to affect cell functions in choriocarcinoma.

Governing the invasive trophoblast: current aspects on intra- and extracellular regulation

This review summarizes several aspects especially of regulating factors governing trophoblast invasion. Those include the composition of the extracellular matrix containing a variety of matrix metalloproeinases and their inhibitors, but also intracellular signals. Furthermore, a newly described trophoblast subtype, the endoglandular trophoblast, is presented. Its presence may provide a possible mechanism for opening and connecting uterine glands into the intervillous space. Amongst others, two intracellular signalling pathways are crucial for regulation of trophoblast functions and development: Wnt- and signal transducer and activator of transcription (STAT)3 signalling. Wnt signalling promotes implantation, placentation and trophoblast differentiation. Several Wnt-dependent cascades and regulatory mechanisms display different functions in trophoblast cells. The STAT3 signalling system is fundamental for induction and regulation of invasiveness in physiological trophoblastic cells, but also in tumours. The role of galectins (Gal) in trophoblast regulation and placenta development comes increasingly into focus. The Gal- 1-4, 7-10 and 12-14 have been detected in humans. Detailed information is only available for Gal-1, -2, -3, -4, -9 and -12 in endometrium and decidua. Gal-1, -3 and -13 (-14) have been detected and studied in trophoblast cells.

Conveying glycan information into T-cell homeostatic programs: a challenging role for galectin-1 in inflammatory and tumor microenvironments

The immune system has evolved sophisticated mechanisms composed of several checkpoints and fail-safe processes that enable it to orchestrate innate and adaptive immunity, while at the same time limiting aberrant or unfaithful T-cell function. These multiple regulatory pathways take place during the entire life-span of T cells including T-cell development, homing, activation, and differentiation. Galectin-1, an endogenous glycan-binding protein widely expressed at sites of inflammation and tumor growth, controls a diversity of immune cell processes, acting either extracellularly through specific binding to cell surface glycan structures or intracellularly through modulation of pathways that remain largely unexplored. In this review, we highlight the discoveries that have led to our current understanding of the role of galectin-1 in distinct immune cell process, particularly those associated with T-cell homeostasis. Also, we emphasize findings emerging from the study of experimental models of autoimmunity, chronic inflammation, fetomaternal tolerance, and tumor growth, which have provided fundamental insights into the critical role of galectin-1 and its specific saccharide ligands in immunoregulation. Challenges for the future will embrace the rational manipulation of galectin-1-glycan interactions both towards attenuating immune responses in autoimmune diseases, graft rejection, and recurrent fetal loss, while at the same overcoming immune tolerance in chronic infections and cancer.

Defining postpartum uterine disease and the mechanisms of infection and immunity in the female reproductive tract in cattle

Uterine microbial disease affects half of all dairy cattle after parturition, causing infertility by disrupting uterine and ovarian function. Infection with Escherichia coli, Arcanobacterium pyogenes, and bovine herpesvirus 4 causes endometrial tissue damage. Toll-like receptors on endometrial cells detect pathogen-associated molecules such as bacterial DNA, lipids, and lipopolysaccharide (LPS), leading to secretion of cytokines, chemokines, and antimicrobial peptides. Chemokines attract neutrophils and macrophages to eliminate the bacteria, although persistence of neutrophils is associated with subclinical endometritis and infertility. Cows with uterine infections are less likely to ovulate because they have slower growth of the postpartum dominant follicle in the ovary, lower peripheral plasma estradiol concentrations, and perturbation of hypothalamic and pituitary function. The follicular fluid of animals with endometritis contains LPS, which is detected by the TLR4/CD14/LY96 (MD2) receptor complex on granulosa cells, leading to lower aromatase expression and reduced estradiol secretion. If cows with uterine disease ovulate, the peripheral plasma concentrations of progesterone are lower than those in normal animals. However, luteal phases are often extended in animals with uterine disease, probably because infection switches the endometrial epithelial secretion of prostaglandins from the F series to the E series by a phospholipase A2-mediated mechanism, which would disrupt luteolysis. The regulation of endometrial immunity depends on steroid hormones, somatotrophins, and local regulatory proteins. Advances in knowledge about infection and immunity in the female genital tract should be exploited to develop new therapeutics for uterine disease.

Galectin-1 on cervical epithelial cells is a receptor for the sexually transmitted human parasite Trichomonas vaginalis

The extracellular protozoan parasite Trichomonas vaginalis causes the most prevalent non-viral sexually transmitted human infection, yet the pathogenesis of infection is poorly understood, and host cell receptors have not been described. The surface of T. vaginalis is covered with a glycoconjugate called lipophosphoglycan (LPG), which plays a role in the adherence and cytotoxicity of parasites to human cells. T. vaginalis LPG contains high amounts of galactose, making this polysaccharide a candidate for recognition by the galactose-binding galectin family of lectins. Here we show that galectin-1 (gal-1) is expressed by human cervical epithelial cells and binds T. vaginalis LPG. Gal-1 binds to parasites in a carbohydrate-dependent manner that is inhibited in the presence of T. vaginalis LPG. Addition of purified gal-1 to cervical epithelial cells also enhances parasite binding, while a decrease in gal-1 expression by small interfering RNA (siRNA) transfection decreases parasite binding. In contrast, the related galectin-7 (gal-7) does not bind T. vaginalis in a carbohydrate-dependent manner, and is unable to mediate attachment of parasites to host cells. Our data are consistent with the presence of multiple host cell receptors for T. vaginalis of which gal-1 is the first to be identified and highlight the importance of glycoconjugates in host-pathogen interactions.

Steroid hormones modulate galectin-1 in the trophoblast HTR-8/SVneocell line

The effects of steroids on galectin-1 (gal-1) were studied in HTR-8/SVneo cells by immunocytochemistry, cell-based ELISA, the MTT proliferation test and the Matrigel TM invasion test. Dexamethasone (DEX), progesterone (PRG), and mifepristone (RU486) were used. Gal-1 was modulated in a steroid- and dose-dependent manner by DEX, which mildly but significantly stimulated production at low concentrations (0.1-10 nM), and inhibited it at 100 nM, while the effects of PRG and RU486 were opposite. HTR-8/SVneo cell invasion of Matrigel was significantly decreased in the presence of DEX and lactose. The obtained data support the proposed regulatory role of steroids in trophoblast gal-1 production.

Expression of galectin-1, -3 (gal-1, gal-3) and the Thomsen-Friedenreich (TF) antigen in normal, IUGR, preeclamptic and HELLP placentas

BACKGROUND

Galectin-1 (gal-1) and galectin-3 (gal-3), which are members of the mammalian beta-galactoside-binding proteins, recognise preferentially (Galbeta1-4GlcNAc) sequences of several cell surface oligosaccharides. In addition, gal-1 also binds to the Thomsen-Friedenreich (TF) antigen (Galbeta1-3GalNAc-).

MATERIALS AND METHODS

Slides of frozen and paraffin-embedded placental tissue of patients with fetal intrauterine growth retardation (IUGR), preeclampsia, haemolysis, elevated liver enzymes, low platelets (HELLP) and normal term placentas were incubated with monoclonal and polyclonal antibodies against gal-1, gal-3 and TF. Staining reaction was performed with the avidin-biotinylated peroxidase complex (ABC) reagent. The intensity of the immunohistochemical reaction on the slides was analysed using a semi-quantitative score. The identity of galectin-expressing cells was analysed by using a double immunofluorescence method.

RESULTS

We demonstrated immunohistochemically that the expression of gal-1 and gal-3 on the extravillous trophoblast (EVT) is significantly up-regulated in preeclamptic and HELLP placentas and unchanged compared with normal controls in IUGR placentas. The expression of the TF antigen is significantly up-regulated in IUGR and preeclamptic extravillous trophoblast cells and unchanged in HELLP placentas compared with normal controls. In addition, the expression of gal-1 is significantly up-regulated in the decidual tissue of preeclamptic placentas and in the villous trophoblast tissue of HELLP placentas.

CONCLUSION

Our data showed that gal-1, gal-3 and TF were up-regulated on the membrane of EVT in preeclamptic placentas. In addition, the expression of gal-1 is significantly up-regulated in decidual tissue of preeclamptic placentas and villous trophoblast tissue of HELLP placentas. Taking into consideration the results of this study, we speculate that expression of both galectins and TF on the membrane of preeclamptic EVT and up-regulation of gal-1 in preeclamptic decidual cells may at least in part compensate for the apoptotic effects of maternal immune cells.

Impact of p53 immunostaining in predicting advanced or recurrent placental site trophoblastic tumors: a study of 12 cases

OBJECTIVES

To identify an indicator that can predict tumor cell spread beyond the uterine corpus.

METHODS

We studied clinicopathology and immunohistochemistry of 12 cases of PSTT. Two cases of epithelioid trophoblastic tumor (ETT) were included as reference cases. For immunohistochemistry, antibodies against Ki-67, p53, human chorionic gonadotropin (hCG), human placental lactogen (hPL), carcinoembryonic antigen (CEA, polyclonal antibodies; pCEA), carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1), and bcl-2 were used. PSTT cases were divided as confined and non-confined groups (CG and NCG, respectively). CG consisted of stage I cases with no evidence of recurrence during the follow-up, while NCG consisted of either advanced (stage II or higher) or recurrent stage I lesions.

RESULTS

Age, the interval from the latest pregnancy, serum hCG/hPL levels, tumor size, mitotic figures, Ki-67 labeling indices, and bcl-2 did not discriminate NCG from CG. CEACAM1 and CEA-related antigens as determined by polyclonal anti-CEA antibodies were specifically stained in PSTT cells, but they could not discriminate groups. p53 was positive in PSTT cells in NCG (6/6, 100%), while it was positive in only one case of CG (1/6, 16.7%), indicating a possible usefulness of p53 immunostaining in predicting an invasive or recurrent propensity of PSTT cells (p=0.015).

CONCLUSIONS

This finding also suggests the importance of p53 function in the biology of PSTT cells.

Carcinoembryonic Antigen and Related Molecules in Normal and Transformed Trophoblast

Carcinoembryonic antigen (CEA, CD66e) and CEA-related cell adhesion molecules (CEACAMs) are important mediators in remodeling of diverse human tissues, and modulators of cell proliferation and differentiation. Expression by normal and transformed trophoblast of gestational trophoblastic diseases (GTDs), isolated cytotrophoblast and choriocarcinoma cell lines is presented here. Immunocyto/histochemistry of normal placenta (n=9), invasive mole (n=8), choriocarcinoma (n=7), a placental site trophoblastic tumor, cytotrophoblast in primary culture and JAr and JEG-3 cells was performed using polyclonal anti-CEA and specific monoclonal anti-CEA antibodies. Data were analyzed and scored using Mann-Whitney Test. CEA and CEA-related molecules were identified by Western blot and immunoaffinity chromatography in JAr and JEG-3 cells and extracts of 1st and 3rd trimester of pregnancy tissue and cytotrophoblast cell lysates. CEA is expressed throughout pregnancy, in first trimester predominantly in syncytiotrophoblast, but also in villous cytotrophoblast and extravillous trophoblast. Data presented here demonstrate that CEA is significantly increased in transformed trophoblast of GTDs (p<0.05). Both cytotrophoblast in primary culture and choriocarcinoma cell lines express CEA, with staining of granular deposits in JAr and cell membrane in JEG-3. The results suggest that CEA (CD66e) and other CEA-related protein(s) could be involved in trophoblast differentiation.

Galectin-1: a small protein with major functions

Galectins are a family of carbohydrate-binding proteins with an affinity for beta-galactosides. Galectin-1 (Gal-1) is differentially expressed by various normal and pathological tissues and appears to be functionally polyvalent, with a wide range of biological activity. The intracellular and extracellular activity of Gal-1 has been described. Evidence points to Gal-1 and its ligands as one of the master regulators of such immune responses as T-cell homeostasis and survival, T-cell immune disorders, inflammation and allergies as well as host-pathogen interactions. Gal-1 expression or overexpression in tumors and/or the tissue surrounding them must be considered as a sign of the malignant tumor progression that is often related to the long-range dissemination of tumoral cells (metastasis), to their dissemination into the surrounding normal tissue, and to tumor immune-escape. Gal-1 in its oxidized form plays a number of important roles in the regeneration of the central nervous system after injury. The targeted overexpression (or delivery) of Gal-1 should be considered as a method of choice for the treatment of some kinds of inflammation-related diseases, neurodegenerative pathologies and muscular dystrophies. In contrast, the targeted inhibition of Gal-1 expression is what should be developed for therapeutic applications against cancer progression. Gal-1 is thus a promising molecular target for the development of new and original therapeutic tools.

Influence of IGF-I on adhesion, proliferation, and galectin-1 production in JAr and Jeg-3 choriocarcinoma cell lines

BACKGROUND: JAr and Jeg-3 choriocarcinoma cell lines are model systems for the transformed trophoblast and allow studies of phenotype and regulatory factors for particular cell functions. Both cell lines express the receptor for insulin-like growth factor-I (IGF-I). Effects of IGF-I on adhesion, proliferation and galectin-1 production in JAr and Jeg-3 cells were studied. METHODS: The effects of IGF-I on proliferation and galectin-1 production were examined by thiazolyl blue assay and cell based solid phase assay using polyclonal anti-galectin-1 antibodies. The cell adhesion assay was performed on Matrigel coated wells. Galectin-1 production and localization was examined by immunocytochemistry. RESULTS: IGF-I decreased adhesion of JAr cells to 70% of the control value (p<0.05). Cell treatment with 10 ?g/L of IGF-I significantly increased viable cell number: by 13.5% in JAr and 6% in Jeg-3. Gal-1 was immunolocalized intracellularly and associated with the cell membrane in both cell lines. Production of galectin-1 was significantly increased after treatment with IGF-I compared to control: by 7% in JAr cells and by 16% in Jeg-3 cells (p<0.05). CONCLUSION: The data showed that IGF-I affected adhesion and proliferation of choriocarcinoma cells, depending on the cell line. Both choriocarcinoma cell lines studied here produced galectin-1. The amount of galectin-1 was moderately stimulated by IGF-I.