Glycodelin from seminal plasma is a differentially glycosylated form of contraceptive glycodelin-A

The dependence between glycodelin and selected metalloproteinases concentrations in bovine placenta during early gestation and parturition with and without retained foetal membranes

Pregnancy course depends on the appropriate connection between the mother and the developing foetus. Pregnancy is completed when the placenta is timely expelled. Placental retention is one of the possible pregnancy complications. Extracellular matrix, including adhesive proteins and enzymes that can break down collagens, seems to be responsible for it. The aim of the present study was to examine the impact of one of the adhesive proteins - glycodelin (Gd) - on selected metalloproteinases degrading collagens (MMP2, MMP3, MMP7). Placental tissues from healthy pregnant cows collected during early-mid pregnancy (2nd month n = 7, 3rd month n = 8, 4th month n = 6) and in cows that properly released placenta (NR; n = 6) and cows with retained foetal membranes (R; n = 6) were experimental material. The concentrations of glycodelin and protein content of selected metalloproteinases were measured by ELISA in the maternal and foetal placental homogenates as well as in the culture of epithelial cells derived from the maternal part of the placenta. The presence of these protein molecules was confirmed by Western Blotting. In the bovine placenta, the concentrations of examined proteins exhibit significant changes during placental formation. Gd, MMP3 and MMP7 concentrations decrease with pregnancy progress (between the 2nd and 4th month), while MMP2 concentrations were on the same level in this period. During parturition, concentrations of Gd and MMP3 were significantly higher in the R group compared to the NR group. In parallel, MMP2 concentrations did not show significant differences between the groups (NR vs R), and MMP7 concentrations decreased significantly in the maternal part of the placenta in cows with retained foetal membranes (R). Obtained results show correlations between the gestational age and proteins' (Gd, MMP3, MMP7) concentration, both in the maternal and foetal part of the placenta.

The pregnancy-associated protein glycodelin as a potential sex-specific target for resistance to immunotherapy in non-small cell lung cancer

Lung cancer has been shown to be targetable by novel immunotherapies which reactivate the immune system and enable tumor cell killing. However, treatment failure and resistance to these therapies is common. Consideration of sex as a factor influencing therapy resistance is still rare. We hypothesize that the success of the treatment is impaired by the presence of the immunosuppressive pregnancy-associated glycoprotein glycodelin that is expressed in patients with non-small-cell lung cancer (NSCLC). We demonstrate that the glycan pattern of NSCLC-derived glycodelin detected by a lectin-based enrichment assay highly resembles amniotic fluid-derived glycodelin A, which is known to have immunosuppressive properties. NSCLC-derived glycodelin interacts with immune cells in vitro and regulates the expression of genes associated with inflammatory and tumor microenvironment pathways. In tumor microarray samples of patients, high glycodelin staining in tumor areas results in an impaired overall survival of female patients. Moreover, glycodelin colocalizes to tumor infiltrating CD8+ T cells and pro-tumorigenic M2 macrophages. High serum concentrations of glycodelin prior to immunotherapy are associated with a poor progression-free survival (p < 0.001) of female patients receiving PD-(L)1 inhibitors. In summary, our findings suggest that glycodelin not only is a promising immunological biomarker for early identification of female patients that do not benefit from the costly immunotherapy, but also represents a promising immunotherapeutic target in NSCLC to improve therapeutic options in lung cancer.

Seminal Plasma Glycoproteins as Potential Ligands of Lectins Engaged in Immunity Regulation

Environmental pollution, chronic stress, and unhealthy lifestyle are factors that negatively affect reproductive potential. Currently, 15-20% of couples in industrialized countries face the problem of infertility. This growing health and social problem prompts researchers to explore the regulatory mechanisms that may be important for successful fertilization. In recent years, more attention has been paid to male infertility factors, including the impact of seminal plasma components on regulation of the female immune response to allogenic sperm, embryo and fetal antigens. Directing this response to the tolerogenic pathway is crucial to achieve a healthy pregnancy. According to the fetoembryonic defense hypothesis, the regulatory mechanism may be associated with the interaction of lectins and immunomodulatory glycoepitopes. Such interactions may involve lectins of dendritic cells and macrophages, recruited to the cervical region immediately after intercourse. Carbohydrate binding receptors include C type lectins, such as DC-SIGN and MGL, as well as galectins and siglecs among others. In this article we discuss the expression of the possible lectin ligands, highly fucosylated and high mannose structures, which may be recognized by DC-SIGN, glycans of varying degrees of sialylation, which may differ in their interaction with siglecs, as well as T and Tn antigens in O-glycans.

β-Lactoglobulin and Glycodelin: Two Sides of the Same Coin?

The two lipocalins, β-lactoglobulin (βLg) and glycodelin (Gd), are possibly the most closely related members of the large and widely distributed lipocalin family, yet their functions appear to be substantially different. Indeed, the function of β-lactoglobulin, a major component of ruminant milk, is still unclear although neonatal nutrition is clearly important. On the other hand, glycodelin has several specific functions in reproduction conferred through distinct, tissue specific glycosylation of the polypeptide backbone. It is also associated with some cancer outcomes. The glycodelin gene, PAEP, reflecting one of its names, progestagen-associated endometrial protein, is expressed in many though not all primates, but the name has now also been adopted for the β-lactoglobulin gene (HGNC, www.genenames.org). After a general overview of the two proteins in the context of the lipocalin family, this review considers the properties of each in the light of their physiological functional significance, supplementing earlier reviews to include studies from the past decade. While the biological function of glycodelin is reasonably well defined, that of β-lactoglobulin remains elusive.

Altered glycosylation of glycodelin in endometrial carcinoma

Glycodelin is a major glycoprotein expressed in reproductive tissues, like secretory and decidualized endometrium. It has several reproduction related functions that are dependent on specific glycosylation, but it has also been found to drive differentiation of endometrial carcinoma cells toward a less malignant phenotype. Here we aimed to elucidate whether the glycosylation and function of glycodelin is altered in endometrial carcinoma as compared with a normal endometrium. We carried out glycan structure analysis of glycodelin expressed in HEC-1B human endometrial carcinoma cells (HEC-1B Gd) by mass spectrometry glycomics strategies. Glycans of HEC-1B Gd were found to comprise a typical mixture of high-mannose, hybrid, and complex-type N-glycans, often containing undecorated LacNAc (Galβ1-4GlcNAc) antennae. However, several differences, as compared with previously reported glycan structures of normal human decidualized endometrium-derived glycodelin isoform, glycodelin-A (GdA), were also found. These included a lower level of sialylation and more abundant poly-LacNAc antennae, some of which are fucosylated. This allowed us to select lectins that showed different binding to these classes of glycodelin. Despite the differences in glycosylation between HEC-1B Gd and GdA, both showed similar inhibitory activity on trophoblast cell invasion and peripheral blood mononuclear cell proliferation. For the detection of cancer associated glycodelin, we established a novel in situ proximity-ligation based histochemical staining method using a specific glycodelin antibody and UEAI lectin. We found that the UEAI reactive glycodelin was abundant in endometrial carcinoma, but virtually absent in normal endometrial tissue even when glycodelin was strongly expressed. In conclusion, we established a histochemical staining method for the detection of endometrial carcinoma-associated glycodelin and showed that this specific glycodelin is exclusively expressed in cancer, not in normal endometrium. Similar methods can be used for studies of other glycoproteins.

The Potential Role of Seminal Plasma in the Fertilization Outcomes

For human infertility both male and female factors may be equally important. Searching for molecular biomarkers of male infertility, neglected for decades, and the attempts to explain regulatory mechanisms of fertilization become thus extremely important. Apart from examination of the structure and function of male gametes, also the possible importance of seminal plasma components should be considered. In this article we discuss data that indicate for the substantial significance of active seminal plasma components for conception and achievement of healthy pregnancy. Seminal plasma impact on the storage and cryopreservation of human and animal sperm and regulatory role of glycodelin on human sperm capacitation as well as hypothesized course of female immune response to allogenic sperm and conceptus has been discussed. The possible involvement of carbohydrates in molecular mechanism of fetoembryonic defense has been also mentioned.

Bacterial Biodegradation of 4-Monohalogenated Diphenyl Ethers in One-Substrate and Co-Metabolic Systems

The use of diphenyl ether (DE) and its 4-monohalogenated derivatives (4-HDE) as flame retardants, solvents, and substrates in biocide production significantly increases the risk of ecosystem contamination. Their removal is important from the point of view of environmental protection. The aim of this study was to evaluate the degradation processes of DE and 4-HDE by enzymes of the environmental bacterial strains under one-substrate and co-metabolic conditions. The study is focused on the biodegradation of DE and 4-HDE, the enzymatic activity of microbial strains, and the cell surface properties after contact with compounds. The results show that the highest biodegradation (96%) was observed for 4-chlorodiphenyl ether in co-metabolic culture with P. fluorescens B01. Moreover, the activity of 1,2-dioxygenase during degradation of 4-monohalogenated diphenyl ethers was higher than that of 2,3-dioxygenase for each strain tested. The presence of a co-substrate provoked changes in dioxygenase activity, resulting in the increased activity of 1,2-dioxygenase. Moreover, the addition of phenol as a co-substrate allowed for increased biodegradation of the diphenyl ethers and noticeable modification of the cell surface hydrophobicity during the process. All observations within the study performed have led to a deeper understanding of the contaminants’ biodegradation processes catalyzed by environmental bacteria.

The Roles of Glycodelin in Cancer Development and Progression

Glycodelin is a kind of glycoprotein expressed in secretory endometrium, pregnancy deciduas, and amniotic fluid originally, which is vital for the maintenance of normal human reproductive activities. Recent researches have reported that glycodelin is specifically expressed in various malignancies, including female-specific cancers such as endometrial cancer, ovarian cancer and breast cancer, and non-gender specific cancers including lung cancer, and colon cancer, and glycodelin expression correlates with the diagnosis and prognosis of cancer patients. This review focuses on the expression of glycodelin in different cancers and its role in cancer development and progression. Glycodelin possesses the abilities to regulate cancer cell proliferation, differentiation, and invasion, promote cancer angiogenesis, and modulate the differentiation and function of immune cells including T cells, dendritic cells, monocyte-macrophages, natural killer cells and B cells participating in cancer development. The expression of glycodelin can be regulated by stromal cells, lysophosphatidic acid, histone deacetylase inhibitors, and relaxin. In summary, glycodelin is a promising biomarker for the diagnosis and prognosis of cancer patients, and depending on its distinct immunoregulatory effects, glycodelin can be a prospective target for cancer immunotherapy.

Verification of protein biomarker specificity for the identification of biological stains by quadrupole time-of-flight mass spectrometry

Advances in proteomics technology over the past decade offer forensic serologists a greatly improved opportunity to accurately characterize the tissue source from which a DNA profile has been developed. Such information can provide critical context to evidence and can help to prioritize downstream DNA analyses. Previous proteome studies compiled panels of "candidate biomarkers" specific to each of five body fluids (i.e., peripheral blood, vaginal/menstrual fluid, seminal fluid, urine, and saliva). Here, a multiplex quadrupole time-of-flight mass spectrometry assay has been developed in order to verify the tissue/body fluid specificity the 23 protein biomarkers that comprise these panels and the consistency with which they can be detected across a sample population of 50 humans. Single-source samples of these human body fluids were accurately identified by the detection of one or more high-specificity biomarkers. Recovery of body fluid samples from a variety of substrates did not impede accurate characterization and, of the potential inhibitors assayed, only chewing tobacco juice appeared to preclude the identification of a target body fluid. Using a series of 2-component mixtures of human body fluids, the multiplex assay accurately identified both components in a single-pass. Only in the case of saliva and peripheral blood did matrix effects appear to impede the detection of salivary proteins.

Preliminary MALDI-TOF-MS analysis of seminal plasma N-glycome of infertile men

Glycosylation pattern within reproductive tract is now suggested to be involved in providing female immune tolerance for allograft sperm and developing embryo, but the information whether impaired glycosylation may influence male fertility potential is still limited. We have analyzed seminal plasma N-glycome in pooled samples derived from fertile and infertile men by means of MALDI-TOF/TOF tandem mass spectrometry. Among infertile subjects, normozoospermic, oligozoospermic, asthenozoospermic and oligoasthenozoospermic samples were obtained. Eighty-six oligosaccharides were identified in all the analyzed samples. Differences in the content of unique glycans: high mannose and hybrid type, lacking terminal sialic acid and highly fucosylated were found when samples derived from infertile subjects with different semen patterns were compared to the fertile control. The content of highly branched glycans was 3-fold elevated in normozoospermic infertile men, while the expression of highly fucosylated oligosaccharides was increased in asthenozoospermic, oligozoospermic and oligoasthenozoospermic samples. Sialylation of oligosaccharides was decreased in oligozoospermic, oligoasthenozoospermic and especially asthenozoospermic samples, but increased in infertile normozoospermic subjects. Altered glycosylation observed in seminal plasma may reflect similar changes in sperm surface glycoproteins, and may disturb sperm interaction with female immune system. We suggest that at least some cases of unexplained male infertility may be associated with impaired glycosylation.

Glycoprotein fucosylation is increased in seminal plasma of subfertile men

Fucose, the monosaccharide frequent in N- and O-glycans, is a part of Lewis-type antigens that are known to mediate direct sperm binding to the zona pellucida. Such interaction was found to be inhibited in vitro by fucose-containing oligo- and polysaccharides, as well as neoglycoproteins. The objective of this study was to screen seminal plasma proteins of infertile/subfertile men for the content and density of fucosylated glycoepitopes, and compare them to samples of fertile normozoospermic subjects. Seminal proteins were separated in polyacrylamide gel electrophoresis and blotted onto nitrocellulose membrane and probed with fucose-specific Aleuria aurantia lectin (AAL). Twelve electrophoretic bands were selected for quantitative densitometric analysis. It was found that the content, and especially the density of fucosylated glycans, were higher in glycoproteins present in seminal plasma of subfertile men. No profound differences in fucosylation density were found among the groups of normozoospermic, oligozoospermic, asthenozoospermic, and oligoasthenozoospermic subfertile men. According to the antibody probing, AAL-reactive bands can be attributed to male reproductive tract glycoproteins, including prostate-specific antigen, prostatic acid phosphatase, glycodelin and chorionic gonadotropin. Fibronectin, α₁-acid glycoprotein, α₁-antitrypsin, immunoglobulin G and antithrombin III may also contribute to this high fucosylation. It is suggested that the abundant fucosylated glycans in the sperm environment could interfere with the sperm surface and disturb the normal course of the fertilization cascade.

Sugar-coated sperm: Unraveling the functions of the mammalian sperm glycocalyx

Mammalian spermatozoa are coated with a thick glycocalyx that is assembled during sperm development, maturation, and upon contact with seminal fluid. The sperm glycocalyx is critical for sperm survival in the female reproductive tract and is modified during capacitation. The complex interplay among the various glycoconjugates generates numerous signaling motifs that may regulate sperm function and, as a result, fertility. Nascent spermatozoa assemble their own glycans while the cells still possess a functional endoplasmic reticulum and Golgi in the seminiferous tubule, but once spermatogenesis is complete, they lose the capacity to produce glycoconjugates de novo. Sperm glycans continue to be modified, during epididymal transit by extracellular glycosidases and glycosyltransferases. Furthermore, epididymal cells secrete glycoconjugates (glycophosphatidylinositol-anchored glycoproteins and glycolipids) and glycan-rich microvesicles that can fuse with the maturing sperm membrane. The sperm glycocalyx mediates numerous functions in the female reproductive tract, including the following: inhibition of premature capacitation; passage through the cervical mucus; protection from innate and adaptive female immunity; formation of the sperm reservoir; and masking sperm proteins involved in fertilization. The immense diversity in sperm-associated glycans within and between species forms a remarkable challenge to our understanding of essential sperm glycan functions.

The analysis of sialylation, N-glycan branching, and expression of O-glycans in seminal plasma of infertile men

Carbohydrates are known to mediate some events involved in successful fertilization. Although some studies on the glycosylation of seminal plasma proteins are available, the total glycan profile was rarely analyzed as a feature influencing fertilization potential. In this work we aimed to compare some glycosylation traits in seminal plasma glycoproteins of fertile and infertile men. The following findings emerge from our studies: (1) in human seminal plasma the presence and alterations of O-linked glycans were observed; (2) the expression of SNA-reactive sialic acid significantly differs between asthenozoospermia and both normozoospermic (fertile and infertile) groups; (3) the expression of PHA-L-reactive highly branched N-glycans was significantly lower in oligozoospermic patients than in both normozoospermic groups. Indication of the appropriate lectins that would enable the possibly precise determination of the glycan profile seems to be a good supplement to mass spectrum analysis. Extension of the lectin panel is useful for the further research.

The dimeric crystal structure of the human fertility lipocalin glycodelin reveals a protein scaffold for the presentation of complex glycans

Structural study of human glycodelin, which is involved in reproduction, reveals a homodimeric structure ideally suited as scaffold for the presentation of distinct glycans, whereas bioinformatic analysis indicated exclusive occurrence in suborders of primates that have a menstrual cycle.

Endometrial gene expression reveals compromised progesterone signaling in women refractory to embryo implantation

BACKGROUND

Endometrial function is essential for embryo implantation. The aim of this study was to analyze gene expression profiles from individual endometrial samples obtained from women with repeated implantation failure after IVF in oocyte donation programs.

METHODS

Seventeen volunteers were recruited: women who had previously participated as recipients in oocyte donation cycles and repeatedly exhibited implantation failure (Group A, study group, n = 5) or had at least one successful cycle (Group B, control group, n = 6) and spontaneously fertile women (Group C, normal fertility group, n = 6). An endometrial cycle was induced with exogenous estradiol (E2) and progesterone (P) and an endometrial sample was collected on the seventh day of P treatment.

RESULTS

Transcriptome analysis showed 82 genes with consistent differential gene expression when comparing A vs. B and A vs. C. One hundred transcripts differentially expressed in group A vs. B have been shown to be regulated by P, suggesting compromised P signaling in the endometrium. The P receptor (PR) mutation PROGINS was not detected in women from group A. Semi-quantitation of immunoreactive PRA/B, PRB and Sp1 (a transcription factor related to P signaling) in paraffin-embedded endometrial sections, did not show statistically significant differences amongst groups. However immunostaining glycodelin was significantly decreased in endometrial samples from group A.

CONCLUSIONS

We conclude that some cases of repeated implantation failure could be associated with an aberrant gene expression profile. Compromised P signaling might be the underlying mechanism for such endometrial gene expression deregulation in women with repeated implantation failure.

Attenuation of fibroblast growth factor signaling by poly-N-acetyllactosamine type glycans

Fibroblast growth factors (FGFs) and their receptors are expressed in a variety of mammalian tissues, playing a role in development and cell proliferation. While analyzing human sperm motility, we found that sperm treated with endo-β-galactosidase (EBG), which specifically hydrolyzes poly-N-acetyllactosamine type glycans (polyLacs), enhanced motility. Mass spectrometry analysis revealed that sperm-associated polyLacs are heavily fucosylated, consistent with Lewis Y antigen. Immunohistochemistry of epididymis using an anti-Lewis Y antibody before and after EBG treatment suggested that polyLacs carrying the Lewis Y epitope are synthesized in epididymal epithelia and secreted to seminal fluid. EBG-treated sperm elevated cAMP levels and calcium influx, indicating activation of fibroblast growth factor signaling. Seminal fluid polyLacs bound to FGFs in vitro, and impaired FGF-mediated signaling in HEK293T cells.

Glycodelin in reproduction

To achieve a successful pregnancy in humans, sperm is required for capacitation, followed by binding to and entry into an oocyte. Maternal endometrial epithelial cells (EECs) prepare the appropriate implantation environment through regulation of immune cells and endometrial cells. After acquiring endometrial receptivity, a successful pregnancy consists of complex and finely regulated steps involving apposition, adhesion, invasion, and penetration. Glycodelin is a secretory glycoprotein that affects cell proliferation, differentiation, adhesion, and motility. Glycodelin has four glycoforms (glycodelin-A, -S, -F. and -C); differences in glycosylation affect each characteristic function. Glycodelin has a unique temporospatial pattern of expression, primarily in the reproductive tract where glycodelin is mid-secretory phase-dominant. Recent studies have demonstrated that glycodelin protein has the potential to regulate various processes, including immunosuppression, fertilization, and implantation. This review details the orchestrated regulation of successful pregnancy by glycodelin as well as a discussion of the basic characteristics of glycodelin.

Glycodelin A is a prognostic marker to predict poor outcome in advanced stage ovarian cancer patients

BACKGROUND

Glycodelin is a cell surface glycoprotein offering a unique gender specific carbohydrate configuration. Sialylated carbohydrate structures, which are unusual for mammals, characterize Glycodelin isolated from amniotic fluid (Glycodelin A, GdA). Glycodelin in general exerts multiple, partly opposing functions ranging from immunosuppression to cell differentiation. As these markedly influence tumorigenesis, this study aimed to clarify whether expression of different Glycodelin isoforms is related to clinicopathological characteristics and prognosis of ovarian cancer patients. Further the use of Glycodelin as a serum marker in benign and malignant ovarian diseases was evaluated.

METHODS

Ovarian cancer specimens (n = 152) were stained for Glycodelin with carbohydrate and peptide specific antibodies. Associations between Glycodelin expression and histological grading, FIGO stage as well as patient's prognosis were examined. Glycodelin was correlated to expression of gonadotropin receptors and mucin-1, which are discussed as ovarian cancer tissue markers. In addition, Glycodelin serum concentrations were analyzed in patients suffering from benign (n = 73) or malignant (n = 38) ovarian neoplasias.

RESULTS

Glycodelin A was found to be an independent prognostic marker for poor prognosis in advanced ovarian cancer patients. GdA staining correlated with gonadotropin receptor (FSHR and LHCGR) and with hCG expression. Gd expression showed a positive correlation with a tumour-associated epitope of mucin 1 (TA-MUC1). Further, compared to ovarian cancer, serum Gd was increased in patients with benign ovarian tumors.

CONCLUSION

Glycodelin A might be related to tumor aggressiveness and poor clinical outcome in advanced epithelial ovarian cancer. Glycodelin serum levels found in patients suffering from benign ovarian tumors, might contribute to a more global attenuation during progression of these precursor lesions.

Inhibition of effector function but not T cell activation and increase in FoxP3 expression in T cells differentiated in the presence of PP14

Background

T-helper polarization of naïve T cells is determined by a complex mechanism that involves many factors, eventually leading to activation of Th1, Th2, or Th17 responses or alternatively the generation of regulatory T cells. Placental Protein 14 (PP14) is a 28 kDa glycoprotein highly secreted in early pregnancy that is able to desensitize T cell receptor (TCR) signaling and modulate T cell activation.

Methodology/Principal Findings

Prolonged antigen-specific stimulation of T cells in the presence of PP14 resulted in an impaired secretion of IFN-γ, IL-5 and IL-17 upon restimulation, although the cells proliferated and expressed activation markers. Furthermore, the generation of regulatory CD4⁺CD25^highFoxp3⁺ T cells was induced in the presence of PP14, in both antigen-specific as well as polyclonal stimulation. In accordance with previous reports, we found that the induction of FoxP3 expression by PP14 is accompanied by down regulation of the PI3K-mTOR signaling pathway.

Conclusions/Significance

These data suggest that PP14 arrests T cells in a unique activated state that is not accompanied with the acquisition of effector function, together with promoting the generation of regulatory T cells. Taken together, our results may elucidate the role of PP14 in supporting immune tolerance in pregnancy by reducing T cell effector functions along with augmenting Treg differentiation.

Glycoprotein and carbohydrate binding protein expression in the placenta in early pregnancy loss

Glycoproteins expressed at the fetal-maternal interface have been shown to exert immunomodulating effects. Glycodelin, hCG and transferrin have been used in in vitro experiments as ligands to block E-selectin-mediated cell adhesion. We found that glycodelin is a strong inhibitor of the E-selectin-mediated cell adhesion with a 10(3)-fold increase in potency compared to the monovalent tetrasaccharide sialyl Lewis X. HCG with distinct carbohydrate expression is also an effective selectin antagonist, whereas the potency of transferrin is low. This could indicate a possible role of glycodelin, hCG and transferrin in preventing leukocyte adhesion to the fetal trophoblast. In decidual tissue of abortion patients, glycodelin expression was significantly reduced compared to normal gestation. These results were confirmed by in situ hybridization. Moreover, glycodelin expression in endometrial cells in vitro could be stimulated by addition of hCG. Because hCG is down-regulated in women with abortion, we speculate that hCG could be one of the factors regulating glycodelin expression. Galectins are structurally related proteins with the ability to bind beta-galactosides through a conserved carbohydrate recognition domain. Galectin-1 (gal-1) expression in the syncytiotrophoblast is down-regulated in early pregnancy loss. Gal-1 recognizes the Thomsen-Friedenreich disaccharide (Galbeta1-3GalNAc-) on the syncytiotrophoblast and extravillous trophoblast. Gal-1 also inhibited trophoblast cell proliferation but did not induce apoptosis in BeWo cells. Ligation of Gal-1 on trophoblast cells may have regulatory effects on trophoblast cell differentiation. Decreased expression of Gal-1 may partly explain disturbed trophoblast differentiation during early placentation leading to early pregnancy loss.

Immunohistochemistry, glycosylation and immunosuppression of glycodelin in human ovarian cancer

Glycodelins (Gds) are glycoproteins with a gender specific glycosylation. Glycodelin A (GdA) is primarily produced in endometrial and decidual tissue and secreted to amniotic fluid. Glycodelins were also identified in several cancer types, including serous ovarian cancer. Gds act as a T-cell inhibitor and are involved in inactivation of human monocytes. With a Gd peptide antibody, derived from a 15 amino acid sequence of human Gd and in situ hybridization experiments, the expression of Gd in serous, mucinous, endometrioid and clear cell ovarian tumors was identified. In contrast to former investigations with antibodies against GdA, a positive immunohistochemical reaction for Gd was observed in all forms of epithelium ovarian cancer. These results were confirmed with in situ hybridization. In addition, Gd is expressed in granulose cell tumors, a non-epithelial form of ovarian cancer. Furthermore, Gd was purified from ascites fluid of ovarian cancer patients. Ascites Gd showed significant differences in its structure of sialyl Lewis-type oligosaccharides compared to GdA. Additionally, ascites Gd inhibits IL-2 stimulated proliferation of peripheral blood leucocytes and inhibits adhesion of SLe(X)-positive cells to E-selectin. Therefore, Gd could act as an inhibitor of lymphocyte activation and/or adhesion in ovarian cancer.

Glycodelin binding to human ejaculated spermatozoa is correlated with sperm morphology

OBJECTIVE

To investigate glycodelin (Gd) binding to the surface of sperm cells in relation to sperm morphology and seminal plasma Gd.

DESIGN

Retrospective study.

SETTING

University-based IVF Unit, Department of Gynecology and Obstetrics.

PATIENT(S)

A total of 5,749 spermatozoa from 42 patients were analyzed.

INTERVENTION(S)

Evaluation of sperm cell morphology according to World Health Organization criteria, measurement of Gd binding by an immunocytochemical staining method, scoring of Gd binding per spermatozoon, and assessment of Gd levels in seminal plasma Gd by ELISA.

MAIN OUTCOME MEASURE(S)

Glycodelin binding per sperm cell was correlated with ejaculate classes, single cell morphology, and Gd in seminal plasma.

RESULT(S)

Variability was observed in the scoring of sperm surface Gd binding per ejaculate and of the Gd levels (36.4-578.2 microg/mL) in human seminal plasma. Surface and seminal plasma Gd values showed no correlation in all cases. However, Gd adherence to the sperm surface depended on sperm morphology according WHO-criteria. There was reduced Gd binding to normal-shaped male gametes compared with abnormal spermatozoa.

CONCLUSION(S)

Glycodelin binding to human spermatozoa correlates with sperm morphology. The variability of Gd adherence suggests differences in sperm membrane properties according to the quality of the spermatozoa.

Differential sialylation regulates the apoptotic activity of glycodelin A

Glycodelin A (GdA), a dimeric lipocalin, expressed by the uterine endometrium, is an immunomodulatory agent and induces apoptosis in T-cells. In this study we demonstrate that two populations of GdA with subtle differences in their net ionic charge are present in the amniotic fluid and that, apoptotic activity is exhibited only by the population with more sialic acid residues. Significantly, removal of sialic acid residues from the active populations of GdA abrogates the activity of the molecule, suggesting that the extent of sialylation might be a factor regulating the activity of GdA.

Glycosylation related actions of glycodelin: gamete, cumulus cell, immune cell and clinical associations

Glycodelin is an example of a glycoprotein whose complex-type glycans mediate biological actions in human reproduction and immune reactions. Being attached to an identical protein backbone, glycodelin oligosaccharides vary significantly from one reproductive tissue to another and have an effect on its own secretion and role in cell communication. For instance, uterine glycodelin-A inhibits sperm-oocyte interaction by binding on the sperm head. This is a glycosylation-dependent phenomenon, in which fucosyltransferase-5 plays a key role. Glycodelin-S from seminal plasma binds evenly around the sperm head and maintains an uncapacitated state in the spermatozoa, until the isoform is detached during sperm passage through the cervix. Glycodelin-F from follicular fluid and Fallopian tube binds to the acrosomal region of the sperm head, thereby inhibiting both the sperm-oocyte binding and premature progesterone-induced acrosome reaction. The cumulus cells surrounding the oocyte can capture glycodelin-A and -F from the surrounding environment and convert these isoforms to a cumulus cell isoform, glycodelin-C. It differs by glycosylation from the other isoforms, and it too attaches on the sperm head, with the highest density in the equatorial region. Glycodelin-C is capable of detaching the sperm-bound inhibitory isoforms so that the sperm-oocyte binding is enhanced. Glycodelin-A also has immunosuppressive actions directed to cellular, humoral and innate immunity. Although these actions depend mainly on the protein backbone, glycosylation also plays a part. Glycosylated glycodelin may be involved in the protection of spermatozoa against maternal immune reactions, and glycodelin also has apoptogenic activity. Some glycosylation patterns of glycodelin may mask its apoptogenic domain. This review updates the recent research and clinical associations of glycodelin, highlighting the role of glycosylation.

Cumulus oophorus-associated glycodelin-C displaces sperm-bound glycodelin-A and -F and stimulates spermatozoa-zona pellucida binding

Spermatozoa have to swim through the oviduct and the cumulus oophorus before fertilization in vivo. In the oviduct, spermatozoa are exposed to glycodelin-A and -F that inhibit spermatozoa-zona pellucida binding. In this study, we determined whether these glycodelins would inhibit fertilization. The data showed that the spermatozoa without previous exposure to glycodelin-A and -F acquired glycodelin immunoreactivity during their passage through the cumulus oophorus. On the other hand, when glycodelin-A or -F-pretreated spermatozoa were exposed to the cumulus oophorus, the zona pellucida binding inhibitory activity of glycodelin-A and -F was not only removed, but the spermatozoa acquired enhanced zona pellucida binding ability. These actions of the cumulus oophorus were due to the presence of a cumulus isoform of glycodelin, designated as glycodelin-C. The cumulus cells could convert exogenous glycodelin-A and -F to glycodelin-C, which was then released into the surrounding medium. The protein core of glycodelin-C was identical to that in other glycodelin isoforms, as demonstrated by mass spectrum, peptide mapping, and affinity to anti-glycodelin antibody recognizing the protein core of glycodelin. In addition to having a smaller size and a higher isoelectric point, glycodelin-C also had lectin binding properties different from other isoforms. Glycodelin-C stimulated spermatozoazona pellucida binding in a dose-dependent manner, and it effectively displaced sperm-bound glycodelin-A and -F. In conclusion, the cumulus cells transform glycodelin-A and -F to glycodelin-C, which in turn removes the spermatozoazona binding inhibitory glycodelin isoforms and enhances the zona binding capacity of spermatozoa passing through the cumulus oophorus.

Glycodelin: a novel serum anti-inflammatory marker in type 1 diabetic retinopathy during pregnancy

PURPOSE

Inflammation may play a role in the development of diabetic retinopathy during pregnancy. Glycodelin is a glycoprotein whose secretion from the endometrial glands increases during pregnancy. Glycodelin has immunosuppressive properties thought to play a role in the protection of the fetoplacental unit. We studied the role of glycodelin in the development and progression of retinopathy in type 1 diabetes during pregnancy.

METHODS

Retinopathy was graded from fundus photographs in 45 diabetes subjects and nine non-diabetes subjects prospectively during pregnancy. Serum glycodelin concentration was measured by an immunofluorometric assay.

RESULTS

In women with diabetes with progression of retinopathy, serum glycodelin concentration was 263 ng/ml (range 116-505 ng/ml) during the first trimester, 61 ng/ml (range 30-106 ng/ml) during the second trimester, and 29 ng/ml (range 13-53 ng/ml) during the third trimester, compared with values of 595 ng/ml (range 376-870 ng/ml), 104 ng/ml (range 75-228 ng/ml) and 45 ng/ml (range 32-74 ng/ml), respectively, in diabetes subjects without progression (p = 0.005 between the groups). Low glycodelin concentration was associated with progression of diabetic retinopathy in multiple regression analysis. Serum glycodelin concentration was similar in women with and without diabetes throughout pregnancy (p = 0.63 by repeated measures ANOVA).

CONCLUSIONS

Low glycodelin concentration is associated with progression of retinopathy in pregnant women with diabetes. A possible causal relationship between low glycodelin levels and progression of retinopathy may be mediated by the immunomodulatory properties of glycodelin.

Glycodelin is present in pinopodes of receptive-phase human endometrium and is associated with down-regulation of progesterone receptor B

OBJECTIVE

To test the hypothesis that glycodelin is localized on pinopodes and correlates with temporal immunostaining of leukemia inhibitory factor (LIF), LIF receptor (LIFR), and progesterone receptor B (PRB).

DESIGN

Prospective clinical study.

SETTING

Hospital-based reproductive health unit and research laboratories.

PATIENT(S)

Twenty-five healthy fertile women with normal menstrual cycles.

INTERVENTION(S)

Endometrial biopsy specimens were obtained from healthy fertile women in the luteal phase of the menstrual cycle.

MAIN OUTCOME MEASURE(S)

Immunohistochemical staining of glycodelin, ultrastructural immunostaining of glycodelin, and double staining of glycodelin and PRB.

RESULT(S)

Glycodelin is present in the glands when pinopodes appear. Glycodelin is localized on pinopodes but is also secreted from luminal epithelial cells regardless of pinopode formation. There was a negative correlation between glycodelin secretion from the glands and PRB staining. A weak correlation between the presence of LIFR (but not LIF) and glycodelin was found.

CONCLUSION(S)

Pinopode appearance, intense staining of LIFR in pinopodes and glycodelin staining in the glands are synchronized events. Down-regulation of PRB in the endometrium is concomitant with the presence of glycodelin in the endometrium, suggesting interaction.

Roles of glycodelin in modulating sperm function

Glycodelin is a glycoprotein with three well-defined isoforms. They are named as glycodelin-S, glycodelin-A and glycodelin-F. The three isoforms have similar protein core but different carbohydrate moieties. Glycodelin-S is abundant in the human seminal plasma. It suppresses sperm capacitation and in doing so, it maintains the spermatozoa in an uncapacitated state before they enter into the uterine cavity. Glycodelin-A is abundant in the amniotic fluid. It is also secreted from endometrial glands into uterine fluid and is produced by the fallopian tube. Glycodelin-A is the first endogenous glycoprotein that was found to inhibit the binding of spermatozoa to the zona pellucida. The immunosuppressive properties of glycodelin-A suggest that the molecule may protect the spermatozoa from immune attack in the maternal reproductive tract. Glycodelin-F was first found in the follicular fluid, hence its name. It also inhibits spermatozoa-zona pellucida binding. In addition, glycodelin-F suppresses progesterone-induced acrosome reaction, and may serve to prevent premature acrosome reaction. Preliminary findings suggest possible presence of yet another glycodelin isoform in the extracellular matrix of cumulus oophorus. Unlike glycodelin-A and -F, it stimulates spermatozoa-zona pellucida binding. In summary, different isoforms of glycodelin have different biological roles on sperm function, and they act in succession to contribute to the success of fertilization.

Development and characterization of monoclonal antibodies for the immunohistochemical detection of glycodelin A in decidual, endometrial and gynaecological tumour tissues

AIMS

Glycodelin is a glycoprotein with a molecular weight of 28 kDa. Unusual LacdiNAc structures have been identified on glycodelin A, isolated from amniotic fluid. Three major functions of this glycoprotein have been identified. Glycodelin is an immunosuppressive molecule, a marker of morphological differentiation, and a contraceptive. Because no monoclonal antibodies for glycodelin A are commercially available, our aim was to develop and characterize three monoclonal antibodies against this glycoprotein.

METHODS AND RESULTS

Glycodelin A was purified from amniotic fluid by three chromatographic steps and its purity was checked by SDS-PAGE. Antibodies were generated from immunized BALB/c mice. Three IgG1 monoclonal antibodies detecting glycodelin A were cloned. All three antibodies recognized carbohydrate structures of glycodelin A and did not cross-react with glycodelin S. They are applicable to immunohistochemistry (frozen and paraffin sections), ELISA and Western blots.

CONCLUSION

The new antibodies can be used for the detection of glycodelin A in frozen and paraffin-embedded decidual and endometrial tissue. One antibody (A87-B/D2) can be used for the detection of glycodelin in endometrial and ovarian tumour tissues. Because glycodelin A is a major secretory endometrial product during the luteal phase, in early pregnancy and in gynaecological tumours, the new antibodies are, potentially, valuable tools for the study of endometrial development and tumour progression.

Glycodelin reduces carcinoma-associated gene expression in endometrial adenocarcinoma cells

OBJECTIVE

Glycodelin is a major secretory glycoprotein of differentiated endometrial epithelium, rarely expressed in proliferative endometrium or endometrial cancer. We aimed to elucidate its role in growth and gene expression of endometrial adenocarcinoma cells, and hypothesized that glycodelin affects cell growth and tumor-associated gene expression.

STUDY DESIGN

Endometrial adenocarcinoma HEC-1B cells were transfected with glycodelin cDNA in both antisense and sense orientations. Cellular morphology, cell proliferation, and gene expression were compared between native and transfected cells.

RESULTS

Compared with native and antisense-transfected carcinoma cells, sense-transfected, glycodelin-producing carcinoma cells showed reduced proliferation, morphologic changes, and altered expression of cancer-related genes. Notably, anti-apoptotic Bcl-XL and MUC1 genes were down-regulated.

CONCLUSION

Reduction by glycodelin transfection of carcinoma cell proliferation and expression of MUC1 and Bcl-XL is significant because these genes are often overexpressed in human cancers--MUC1 is linked to invasive growth and metastases, and both confer resistance to chemotherapy. These results suggest a novel mechanism whereby malignant growth of endometrial adenocarcinoma cells is regulated.

Meet the multifunctional and sexy glycoforms of glycodelin

Glycodelin, a human-secreted glycoprotein that appears in a small number of glycoforms, exhibits diverse biological activities, such as in contraception and immunosuppression. Moreover, different tissue-specific glycoforms appear to mediate diverse functions. Quite unusually, the glycodelin N-linked glycans differ between the male and female glycoforms. The fact that these glycans are fundamental for exerting the physiological activities of the different glycoforms, makes them an interesting target for glycobiology research. This review will focus on the involvement of the glycans in glycodelin activity and compare between the several glycoforms.

Stimulation of hCG protein and mRNA in first trimester villous cytotrophoblast cells in vitro by glycodelin A

AIM

Human chorionic gonadotropin (hCG) is produced by fetal trophoblast cells and secreted into maternal circulation mainly in the first trimester of pregnancy. Another glycoprotein, glycodelin A, is one of the main products of the maternal decidua during this period. The purpose of this study was to investigate the effect of glycodelin A on hCG release by isolated cytotrophoblast cells in vitro.

METHODS

Cytotrophoblast cells were prepared from human first trimester placenta and incubated with varying concentrations of glycodelin A. Supernatants were assayed for hCG protein concentrations, and quantification of beta hCG mRNA was carried out by RT-PCR. Expression of hCG was analysed in stimulated trophoblast cells and in unstimulated controls by immunocytochemistry.

RESULTS

Glycodelin A induces a dose-dependent increase of hCG production. An increase of hCG expression was measured at 100 and 200 microg/mL glycodelin-A treatment in trophoblast cell culture by TaqMan assay on mRNA level. We found a moderate staining of hCG in control trophoblast cells, whereas a strong hCG staining was seen in glycodelin A-treated trophoblast cells.

CONCLUSIONS

HCG is a marker for the differentiation process of trophoblast cells. Our results suggest that glycodelin A secreted by the decidualized endometrium is involved in the regulation of hormones produced by the trophoblast.

Immunolocalization of glycodelin in the genital tract of rats

Glycodelin, also known as placental protein 14 has been predominantly localized to organs of the human genital tract. Unfortunately the physiological role of glycodelin is largely unknown since it depends on limited availability of tissues. Therefore, a suitable animal model to study the role of glycodelin would be desirable. Previously, it was shown that glycodelin mRNA is expressed in the genital tract of male and female rats. In the present study, we demonstrate the expression of glycodelin protein in male and female rats by immunohistochemistry and Western blot analysis. For this purpose a polyclonal antibody was generated against glycodelin peptide. In female rats, glycodelin was found in the epithelial gland cells of the uterus, epithelial cells of the fallopian tube as well as in corpora lutea, interstitial and theca cells of the ovary. Glycodelin was distributed in all epithelial cells of the epididymis and the seminal vesicle. In the seminiferous epithelium, glycodelin was seen in all developmental stages of spermatogonia and spermatocytes and in Sertoli cells. Whereas in the rat male reproductive tract glycodelin expression is slightly different from human or primate tissues, in organs of the rat female genital tract glycodelin expression is similar to humans and primates.

Late follicular phase administration of levonorgestrel as an emergency contraceptive changes the secretory pattern of glycodelin in serum and endometrium during the luteal phase of the menstrual cycle

This study examined serum glycodelin concentrations and endometrial expression during the luteal phase following oral administration of levonorgestrel (LNG) at different stages of the ovarian cycle. Thirty women were recruited and allocated into three groups. All groups were studied during two consecutive cycles, a control cycle and the treatment cycle. In the treatment cycle, each woman received two doses of 0.75 mg LNG taken 12 h apart on days 3-4 before the luteinizing hormone (LH) surge (Group 1), at the time of LH rise (Group 2) and 48 h after the rise in LH was detected (Group 3). Serum progesterone (P) and glycodelin were measured daily during the luteal phase, and an endometrial biopsy was taken at day LH +9 for immunohistochemical glycodelin-A staining. In Group 1, serum P levels were significantly lower, serum glycodelin levels rose earlier and endometrial glycodelin-A expression was weaker than in Groups 2 and 3, in which no differences were found between control and treatment cycles. Levonorgestrel taken for emergency contraception (EC) prior to the LH surge alters the luteal phase secretory pattern of glycodelin in serum and endometrium. Based on the potent gamete adhesion inhibitory activity of glycodelin-A, the results may account for the action of LNG in EC in those women who take LNG before the LH surge.

Glycodelin responses to hyperinsulinaemic clamp vary according to basal serum glycodelin concentration

OBJECTIVE

Treatment with metformin, an insulin-lowering agent, increases serum glycodelin, a progesterone-regulated lipocalin protein of the reproductive axis that may play a role in foeto-maternal defence mechanisms. This finding led to the hypothesis that insulin might decrease serum glycodelin concentration.

DESIGN, PATIENTS AND MEASUREMENTS

Euglycaemic hyperinsulinaemic clamp experiments (n = 50) were carried out on 28 women of reproductive age (range 25-47 years; mean +/- SEM 39 +/- 1.0 years), and the results were analysed with respect to their baseline serum progesterone (< 10 or > or = 10 nmol/l) and glycodelin (< 10 or > or = 10 microg/l, equivalent to < 357 or > or = 357 pmol/l) concentrations at the onset of the clamp. Ten clamp experiments were performed on five women wearing a levonorgestrel-releasing intrauterine device (IUD), and these were analysed as a separate group.

RESULTS

Contrary to the hypothesis, no acute glycodelin-lowering effect of insulin was found in any of the groups studied. All the small rises in glycodelin levels detected during acute hyperinsulinaemia occurred in the comparisons of medians and not means, and all such changes took place within the limits seen in the women with no progesterone exposure. In the group with low progesterone/low glycodelin (n = 21), glycodelin showed a small but significant increase at 30 and 90 min of the clamp (P < 0.01). In the group with elevated progesterone/low glycodelin (n = 11), there was a slight glycodelin increase at 30 min (P < 0.05), whereas no increase was found in the group with elevated glycodelin levels (n = 8). In the clamp experiments on women with levonorgestrel-releasing IUD, the basal glycodelin level was low in all cases and, as in the other women with low glycodelin levels, glycodelin was slightly increased at 30, 60 and 90 min of hyperinsulinaemia (P < 0.01).

CONCLUSIONS

The results rule out any acute glycodelin-reducing effects of insulin, although indirect long-term effects mediated by insulin on glycodelin secretion cannot be excluded.

Expression of glycodelin A in decidual tissue of preeclamptic, HELLP and intrauterine growth-restricted pregnancies

During pregnancy, the placenta produces a variety of proteins that are responsible for the establishment of the foeto-maternal tolerance and circulation. The aim of this study was to investigate the expression of glycodelin A (formerly named PP14) in decidual tissue of placentas with intrauterine growth restriction (IUGR), preeclamptic patients, hemolysis, elevated liver, low-platelet (HELLP) patients and normal decidual tissue. Slides of paraffin-embedded decidual tissue of patients with IUGR, preeclamptic patients, HELLP patients and normal-term placentas were incubated with either polyclonal or monoclonal antibodies against glycodelin A. Staining reaction was performed with the ABC reagent. Intensity of immunohistochemical reaction on the slides was analysed using a semi-quantitative score. In addition, expression of glycodelin mRNA was analysed by in situ hybridisation. Expression of glycodelin A was significantly reduced in decidual cells of placentas with IUGR and HELLP, as investigated with both monoclonal and polyclonal antibodies and in situ hybridisation. However, preeclamptic decidual tissue showed no significantly different expression of intensity of glycodelin mRNA compared with normal placental tissue controls. A reduced expression of glycodelin A by decidual cells seems to be related to IUGR and HELLP. Therefore, glycodelin A might play an important role in the pathogeneses of these diseases.

Cord serum glycodelin concentrations in normal pregnancies and pregnancies complicated by diabetes

OBJECTIVE

Glycodelin is a glycoprotein released by secretory/decidualized endometrial glands. Its synthesis increases during pregnancy. Hormonal factors whose levels have been shown to change in diabetes (vascular endothelial growth factor, relaxin) may mediate the actions or regulate the synthesis of glycodelin. Cord serum glycodelin levels have not been studied in pregnancies complicated by diabetes.

METHODS

Cord serum glycodelin concentrations were measured at birth by an immunofluorometric assay in 62 normal pregnancies, in 67 pregnancies complicated by type 1 diabetes, and in 28 pregnancies complicated by insulin-treated gestational diabetes.

RESULTS

The mean glycodelin concentration in cord serum was 2.7 ng/ml (standard error of the mean 0.6) in normal pregnancies. The concentration was not altered in pregnancies complicated by diabetes. Cord serum glycodelin concentrations were also unaltered in diabetic pregnancies with hypertensive disorders (chronic hypertension, pregnancy-induced hypertension or pre-eclampsia) or fetal macrosomia. There was a negative borderline correlation between cord serum glycodelin concentrations and the birth weight in pregnancies complicated by diabetes (r=-0.21, p=0.049).

CONCLUSIONS

Decidual function, as assessed by cord serum glycodelin levels, is not markedly altered in diabetic pregnancies. The negative correlation between cord serum glycodelin and the birth weight of the newborns in diabetic pregnancies may be due to the decline in glycodelin levels with advancing pregnancy in the third trimester.

Advances in uterine protein research: reproduction and cancer

Uterine protein research has advanced from the measurements of specific compounds to detailed analysis of the genes that regulate protein synthesis and build up the complex carbohydrate structures that play important functional roles. Some 80% of all human proteins are glycoproteins. Functional glycomics highlights the importance of glycosylation in glycoprotein function. Glycodelin is a representative example of functional glycomics because its various glycoforms have different functions. In the uterus, synthesis of glycodelin-A is temporally regulated by progesterone. During the estrogen-dominated fertile window, absence of glycodelin synthesis is significant because uterine glycodelin-A potently and dose-dependently inhibits sperm-egg binding, the initial step in fertilization. The anti-fertilization propensity of glycodelin-A during the luteal phase of the cycle is highly glycosylation-dependent, and there is an intricate functional interplay between spermatozoa, zona pellucida and the various glycodelin isoforms present in the uterine fluid, seminal plasma and follicular fluid, respectively. Endometrial glycodelin synthesis can be induced during the fertile window by administration of progestagens, such as in levonorgestrel hormone-releasing IUD and contraceptive implants. Glycodelin can be chemically modified in such a fashion that it blocks the binding site on CD4 for the HIV surface glycoprotein, synthesis of viral gp 120, and infection of peripheral blood mononuclear cells by the primary HIV isolate THA/93/051, thus potentially inhibiting HIV transmission. Now that a cell line producing the contraceptive isoform has been identified by recombinant technology, these findings may have application for locally applied antiviral contraception. Glycodelin also has immunosuppressive properties, suggesting that the recognition mechanisms in immune and reproductive systems may have converged. Given its inhibitory activity on natural killer cells, abundant at the fetomaternal interphase, the high glycodelin concentration at the same site suggests a role in fetomaternal defense mechanisms. This may be relevant in women with recurrent miscarriage, in whom both the serum and uterine fluid glycodelin concentrations are decreased. Experiments on cancer cell lines have demonstrated increased epithelial differentiation by glycodelin cDNA transfection, and also by co-culture of cancer cells with normal stromal cells in the presence of basement membrane components. Both approaches result in glycodelin expression concomitant with decreased cell proliferation and reversion of the malignant phenotype. These results suggest an active role of normal stromal cells, basement membrane components and glycodelin in epithelial differentiation and glandular morphogenesis. This disposition of glycodelin is significant in patients with certain carcinomas, in which glycodelin-expressing tumors carry better prognosis than glycodelin-negative tumors of the same clinical stage and histological grade. Research on functional glycomics continues to produce significant information on fundamental aspects of fertilization, implantation, pregnancy and cancer.

Molecular cloning and characterization of β1,4-N-acetylgalactosaminyltransferases IV synthesizingN,N′-diacetyllactosediamine1

A sequence highly homologous to beta1,4-N-acetylgalactosaminyltransferase III (beta4GalNAc-T3) was found in a database of human expressed sequence tags. The full-length open reading frame of the gene, beta4GalNAc-T4 (GenBank accession number AB089939), was cloned using the 5' rapid amplification of cDNA ends method. It encodes a typical type II transmembrane protein of 1039 amino acids having 42.6% identity with beta4GalNAc-T3. The recombinant enzyme transferred N-acetylgalactosamine to N-acetylglucosamine-beta-benzyl with a beta1,4-linkage to form N,N'-diacetyllactosediamine as did beta4GalNAc-T3. In specificity toward oligosaccharide acceptor substrates, it was quite similar to beta4GalNAc-T3 in vitro, however, the tissue distributions of the two enzymes were quite different. These results indicated that the two enzymes have similar roles in different tissues.

Analysis of the Role of Oligosaccharides in the Apoptotic Activity of Glycodelin A

Glycodelin A, also known as placental protein-14, is a multifunctional glycosylated protein secreted by the uterine endometrium during the early phases of pregnancy. It is a known suppressor of T cell proliferation, inducer of T cell apoptosis, and inhibitor of sperm zona binding. Unlike in contraceptive activity, where the glycans on the molecule have been shown to play a crucial role, mutagenesis of the asparagines at sites of N-linked glycosylation (Asn(28) and Asn(63)) to glutamine shows that the apoptogenic activity of glycodelin A is executed by the protein backbone. Glycosylation at Asn(28) appears to play a role in the extracellular secretion of the molecule, as mutation of Asn(28) resulted in a significant decrease in the amount of secreted protein, and loss of both glycosylation sites reduced the secretion drastically. Our results also suggest that the loss of glycosylation does not affect the dimerization status of the molecule.

Human embryo implantation: current knowledge and clinical implications in assisted reproductive technology

A pregnancy rate of approximately 15% per cycle renders the process of human reproduction inefficient. The cycle-dependent expression of molecules involved in the embryo-endometrial dialogue has lead to the identification of a 'window of implantation'. This is the unique temporal and spatial expression of factors that allows the embryo to implant (via signalling, appositioning, attachment and invasion) in a specific time frame of 48 h, 7-10 days after ovulation. Integrin molecules, L-selectin ligands, mucin-1, heparin-binding epidermal growth factor and pinopodes are involved in appositioning and attachment. The embryo produces cytokines and growth factors [interleukins, prostaglandins, vascular endothelial growth factor (VEGF)] and receptors for endometrial signals (leukaemia inhibitory factor receptor, colony stimulating factor receptor, insulin-like growth factors and heparin binding epidermal growth factor receptor). The immune system plays an important role. Immunomodulatory factors such as glycodelin, inhibin and interleukin prevent a graft-versus-host reaction. Angiogenesis controlled by VEGF and prostaglandins is needed for formation of a receptive endometrium and a placenta. Identification of these factors has led to their use as markers of implantation that may identify defects causing subfertility. An ideal marker of implantation is sensitive and specific, and easy to obtain without disturbing implantation. Glycodelin and leukaemia inhibitory factor (serum) and integrins and pinopodes (biopsies) are promising candidates.

Placental protein 14 concentrations in circulation related to hormonal parameters and reproductive outcome in women undergoing IVF/ICSI

Serum concentrations of placental protein 14 (PP14), steroids and gonadotrophins were related to the outcome of IVF/intracytoplasmic sperm injection in 195 normogonadotrophic women subjected to the long protocol gonadotrophin-releasing hormone agonist (GnRHa; buserelin) pituitary down-regulation protocol and gonadotrophin stimulation (HMG or rFSH). Pituitary down-regulation was initiated on cycle day 21 and the patients were randomized to either intranasal or s.c. administration of buserelin. After 14 days of down-regulation, the patients were randomized on stimulation day 1 (S1) to ovarian stimulation with 225 IU per day of either human menopausal gonadotrophin (HMG) or recombinant FSH (rFSH) for a fixed period of 7 days. The daily gonadotrophin dose was adjusted on the following day according to ovarian response. Patient's blood was sampled for PP14 and hormone analysis on cycle days 21, S1, S8 and on the day of oocyte retrieval. Mean concentrations of PP14 on day 21 of the cycle were significantly lower in conception than in non-conception cycles, whereas progesterone and oestradiol were similar in conception and non-conception cycles. PP14 concentrations on the first day of stimulation and at oocyte retrieval were significantly higher in conception than in non-conception cycles, whereas concentrations after 8 days of stimulation were similar. Neither mode of GnRHa administration nor type of gonadotrophin significantly influenced PP14 concentrations throughout ovarian stimulation. Circulating PP14 is thus an important physiological signal of the fertility status of the individual in the cycle antecedent to and during ovarian stimulation. Measuring mid-luteal serum PP14 may offer a clinical test helping to decide if infertility treatment should be initiated in the subsequent cycle.

Glycodelin A, not glycodelin S, is apoptotically active. Relevance of sialic acid modification

Glycodelin, previously known as PP14 (placental protein-14), is a kernel lipocalin secreted by the glandular epithelium of the endometrium upon progesterone stimulation and by the seminal vesicles. The isoform of the protein present in female reproductive tissue, glycodelin A (GdA), and the male counterpart, glycodelin S (GdS), have identical amino acid sequences, but strikingly different N-linked glycans. It is well documented in literature that GdA is an immunosuppressive protein, and we have shown that this activity is due to its ability to induce apoptosis in activated T cells. The precise role of GdS in seminal plasma is not known. In this study, we report that GdS is not apoptotically active. We observe that the apoptotic activity requires the presence of sialic acid residues on the complex glycans, as in the case of GdA; however, complex glycans of GdS are non-sialylated. We have expressed the wild-type protein in Pichia pastoris, which does not add sialic acid to the secreted proteins, and confirmed our observations that the protein is apoptotically inactive in the non-sialylated form. Our results indicate that differential glycosylation modulates the function of the different glycodelin isoforms.

Differences in glycosylation and sperm-egg binding inhibition of pregnancy-related glycodelin

Glycodelin is a glycoprotein produced in many glands, particularly those of reproductive tissues. It appears as different glycoforms in amniotic fluid (glycodelin-A) and seminal plasma (glycodelin-S), but only glycodelin-A inhibits gamete adhesion. In the present study, glycodelin from secretory-phase endometrium, first-trimester pregnancy decidua, and midtrimester amniotic fluid was studied with respect to physicochemical properties, including glycosylation patterns and inhibitory activity of sperm-egg binding. Purified glycodelins from all these sources were similar in isoelectric focusing and in lectin immunoassays using lectins from Wisteria floribunda and Sambucus nigra. Likewise, the glycodelins inhibited sperm-egg binding in a dose-dependent manner, as measured by hemizona-binding assay. However, subtle quantitative physicochemical and biological differences were found between glycodelins from different sources as well as within the same tissue/fluid between different individuals. Differences were most pronounced between endometrial glycodelins from nonpregnancy and first-trimester pregnancy. The glycan structures studied by fast-atom bombardment mass spectrometry of individual amniotic fluid glycodelin-A samples also showed interindividual quantitative differences. In conclusion, glycodelins from different female reproductive tract tissues and amniotic fluid share substantial similarity, allowing all of them to be called glycodelin-A. However, these glycodelins exhibit quantitative physicochemical and functional differences between different sources and individuals.

Zona-binding inhibitory factor-1 from human follicular fluid is an isoform of glycodelin

Zona-binding inhibitory factor-1 (ZIF-1), a glycoprotein in human follicular fluid, reduces the binding of spermatozoa to the zona pellucida. ZIF-1 has a number of properties similar to those of glycodelin-A from human follicular fluid. The objective of this study was to compare the biochemical characteristics of these two glycoproteins. N-terminal sequencing and protease-digested peptide mapping showed that ZIF-1 and glycodelin-A have the same protein core. However, these glycoproteins differ in their oligosaccharide chains, as demonstrated by fluorophore-assisted carbohydrate electrophoresis, lectin-binding ability, and isoelectric focusing. ZIF-1 inhibited spermatozoa-zona pellucida binding slightly more than did glycodelin-A and significantly suppressed progesterone-induced acrosome reaction of human spermatozoa. Indirect immunofluorescence staining revealed specific binding of glycodelin-A and ZIF-1 to the acrosome region of human spermatozoa, where ZIF-1 produced a stronger signal than did glycodelin-A at the same protein concentration. These data suggest that ZIF-1 is a differentially glycosylated isoform of glycodelin that potently inhibits human sperm-egg interaction. Future study on the function role of ZIF-1 would provide a better understanding of the regulation of fertilization in humans.