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

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.

A systematic review identifying seminal plasma biomarkers and their predictive ability on IVF and ICSI outcomes

The diverse nature and high molecule concentration of seminal plasma (SP) makes this fluid a good potential source for a potential biomarker that could predict assisted reproductive technology (ART) outcomes. Currently, semen quality parameters cannot accurately predict ART outcomes. A systematic literature search was conducted to identify human SP biomarkers with potential predictive ability for the outcomes of IVF and intracytoplasmic sperm injection. Observational cohort and case-control studies describing the association between biomarkers in human SP and the outcome of infertile men attending for ART were included. Forty-three studies were selected, reporting on 89 potential SP biomarkers (grouped as oxidative stress, proteins glycoproteins, metabolites, immune system components, metals and trace elements and nucleic acids). The present review supports 32 molecules in SP as potentially relevant biomarkers for predicting ART outcomes; 23 molecules were reported once and nine molecules were reported in more than one study; IL-18 and TGF-β1-IL-18 ratio were confirmed in distinct studies. This review presents the most comprehensive overview of relevant SP biomarkers to predict ART outcomes to date, which is of clinical interest for infertility investigations and assisted reproduction; nevertheless, its potential is under-exploited. This review could serve as starting point for designing an all-encompassing study for biomarkers in SP and their predictive ability for ART outcomes, and for developing a non-invasive diagnostic tool.

Protein glycosylation: bridging maternal-fetal crosstalk during embryo implantation†

Infertility is a challenging health problem that affects 8-15% of couples worldwide. Establishing pregnancy requires successful embryo implantation, but about 85% of unsuccessful pregnancies are due to embryo implantation failure or loss soon after. Factors crucial for successful implantation include invasive blastocysts, receptive endometrium, invasion of trophoblast cells, and regulation of immune tolerance at the maternal-fetal interface. Maternal-fetal crosstalk, which relies heavily on protein-protein interactions, is a critical factor in implantation that involves multiple cellular communication and molecular pathways. Glycosylation, a protein modification process, is closely related to cell growth, adhesion, transport, signal transduction, and recognition. Protein glycosylation plays a crucial role in maternal-fetal crosstalk and can be divided into N-glycosylation and O-glycosylation, which are often terminated by sialylation or fucosylation. This review article examines the role of protein glycosylation in maternal-fetal crosstalk based on two transcriptome datasets from the GEO database (GSE139087 and GSE113790) and existing research, particularly in the context of the mechanism of protein glycosylation and embryo implantation. Dysregulation of protein glycosylation can lead to adverse pregnancy outcomes, such as missed abortion and recurrent spontaneous abortion, underscoring the importance of a thorough understanding of protein glycosylation in the diagnosis and treatment of female reproductive disorders. This knowledge could have significant clinical implications, leading to the development of more effective diagnostic and therapeutic approaches for these conditions.

The pathophysiological role of estrogens in the initial stages of pregnancy: molecular mechanisms and clinical implications for pregnancy outcome from the periconceptional period to end of the first trimester

BACKGROUND

Estrogens regulate disparate female physiological processes, thus ensuring reproduction. Altered estrogen levels and signaling have been associated with increased risks of pregnancy failure and complications, including hypertensive disorders and low birthweight babies. However, the role of estrogens in the periconceptional period and early pregnancy is still understudied.

OBJECTIVE AND RATIONALE

This review aims to summarize the current evidence on the role of maternal estrogens during the periconceptional period and the first trimester of pregnancies conceived naturally and following ART. Detailed molecular mechanisms and related clinical impacts are extensively described.

SEARCH METHODS

Data for this narrative review were independently identified by seven researchers on Pubmed and Embase databases. The following keywords were selected: 'estrogens' OR 'estrogen level(s)' OR 'serum estradiol' OR 'estradiol/estrogen concentration', AND 'early pregnancy' OR 'first trimester of pregnancy' OR 'preconceptional period' OR 'ART' OR 'In Vitro Fertilization (IVF)' OR 'Embryo Transfer' OR 'Frozen Embryo Transfer' OR 'oocyte donation' OR 'egg donation' OR 'miscarriage' OR 'pregnancy outcome' OR 'endometrium'.

OUTCOMES

During the periconceptional period (defined here as the critical time window starting 1 month before conception), estrogens play a crucial role in endometrial receptivity, through the activation of paracrine/autocrine signaling. A derailed estrogenic milieu within this period seems to be detrimental both in natural and ART-conceived pregnancies. Low estrogen levels are associated with non-conception cycles in natural pregnancies. On the other hand, excessive supraphysiologic estrogen concentrations at time of the LH peak correlate with lower live birth rates and higher risks of pregnancy complications. In early pregnancy, estrogen plays a massive role in placentation mainly by modulating angiogenic factor expression-and in the development of an immune-tolerant uterine micro-environment by remodeling the function of uterine natural killer and T-helper cells. Lower estrogen levels are thought to trigger abnormal placentation in naturally conceived pregnancies, whereas an estrogen excess seems to worsen pregnancy development and outcomes.

WIDER IMPLICATIONS

Most current evidence available endorses a relation between periconceptional and first trimester estrogen levels and pregnancy outcomes, further depicting an optimal concentration range to optimize pregnancy success. However, how estrogens co-operate with other factors in order to maintain a fine balance between local tolerance towards the developing fetus and immune responses to pathogens remains elusive. Further studies are highly warranted, also aiming to identify the determinants of estrogen response and biomarkers for personalized estrogen administration regimens in ART.

Diversity of sialic acids and sialoglycoproteins in gametes and at fertilization

Sialic acids are a family of 9-carbon monosaccharides with particular physicochemical properties. They modulate the biological functions of the molecules that carry them and are involved in several steps of the reproductive process. Sialoglycoproteins participate in the balance between species recognition and specificity, and the mechanisms of these aspects remain an issue in gametes formation and binding in metazoan reproduction. Sialoglycoproteins form a specific coat at the gametes surface and specific polysialylated chains are present on marine species oocytes. Spermatozoa are submitted to critical sialic acid changes in the female reproductive tract facilitating their migration, their survival through the modulation of the female innate immune response, and the final oocyte-binding event. To decipher the role of sialic acids in gametes and at fertilization, the dynamical changes of enzymes involved in their synthesis and removal have to be further considered.

The Influence of Clusterin Glycosylation Variability on Selected Pathophysiological Processes in the Human Body

The present review gathers together the most important information about variability in clusterin molecular structure, its profile, and the degree of glycosylation occurring in human tissues and body fluids in the context of the utility of these characteristics as potential diagnostic biomarkers of selected pathophysiological conditions. The carbohydrate part of clusterin plays a crucial role in many biological processes such as endocytosis and apoptosis. Many pathologies associated with neurodegeneration, carcinogenesis, metabolic diseases, and civilizational diseases (e.g., cardiovascular incidents and male infertility) have been described as causes of homeostasis disturbance, in which the glycan part of clusterin plays a very important role. The results of the discussed studies suggest that glycoproteomic analysis of clusterin may help differentiate the severity of hippocampal atrophy, detect the causes of infertility with an immune background, and monitor the development of cancer. Understanding the mechanism of clusterin (CLU) action and its binding epitopes may enable to indicate new therapeutic goals. The carbohydrate part of clusterin is considered necessary to maintain its proper molecular conformation, structural stability, and proper systemic and/or local biological activity. Taking into account the wide spectrum of CLU action and its participation in many processes in the human body, further studies on clusterin glycosylation variability are needed to better understand the molecular mechanisms of many pathophysiological conditions. They can also provide the opportunity to find new biomarkers and enrich the panel of diagnostic parameters for diseases that still pose a challenge for modern medicine.

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.

Seminal plasma N-glycome as a new biomarker of environmental exposure associated with semen quality

Male infertility, a condition that has during the last decade raised significant concern, is a diagnostically demanding and socially sensitive topic. The number of unsolved issues on infertility etiology, especially potential environmental causes, in couples demonstrates the need for further investigations into infertility biomarkers. Semen parameters are often insufficient for reliable profiling of male infertility. Thus, this study aims to evaluate for the first time seminal plasma N-glycosylation as a biomarker of environmental exposure in semen samples from 82 normozoospermic men and 84 men with abnormal semen parameters and compare it with genome damage measured by DNA fragmentation. We obtained information about chronic exposure to environmental factors from the self-reported questionnaire, and determined sperm DNA fragmentation by sperm chromatin dispersion, while N-glycans were characterized with liquid chromatography-mass spectrometry (LC-MS). Based on previously published results, ten N-glycans were selected. Results show that the selected seminal plasma N-glycans were significantly associated with smoking, exposure to pesticides, air pollution, agents emitted during photocopying, alcohol consumption, and obesity. Some N-glycans showed a simultaneous association with DNA fragmentation, semen parameters, and environmental stressors. These subgroups of N-glycans are new potential candidates for biomonitoring of exposure to different environmental factors in men with semen abnormalities.

Seminal Plasma Protein N-Glycan Peaks Are Potential Predictors of Semen Pathology and Sperm Chromatin Maturity in Men

Background: Male infertility is increasingly becoming a health and demographic problem. While it may originate from congenital or acquired diseases, it can also result from environmental exposure. Hence, the complexity of involved molecular mechanisms often requires a multiparametric approach. This study aimed to associate semen parameters with sperm DNA fragmentation, chromatin maturity and seminal plasma protein N-glycosylation. Methods: The study was conducted with 166 participants, 20–55 y old, 82 normozoospermic and 84 with pathological diagnosis. Sperm was analyzed by Halosperm assay and aniline blue staining, while seminal plasma total protein N-glycans were analyzed by ultra-high-performance liquid chromatography. Results: Sperm DNA fragmentation was significantly increased in the pathological group and was inversely correlated with sperm motility and viability. Seminal plasma total protein N-glycans were chromatographically separated in 37 individual peaks. The pattern of seminal plasma N-glycan peaks (SPGP) showed that SPGP14 significantly differs between men with normal and pathological semen parameters (p < 0.001). The multivariate analysis showed that when sperm chromatin maturity increases by 10%, SPGP17 decreases by 14% while SPGP25 increases by 25%. Conclusion: DNA integrity and seminal plasma N-glycans are associated with pathological sperm parameters. Specific N-glycans are also associated with sperm chromatin maturity and have a potential in future fertility research and clinical diagnostics.

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.

Decidual glycodelin-A polarizes human monocytes into a decidual macrophage-like phenotype through Siglec-7

Decidual macrophages constitute 20-30% of the total leukocytes in the uterus of pregnant women, regulating the maternal immune tolerance and placenta development. Abnormal number or activities of decidual macrophages (dMs) are associated with fetal loss and pregnancy complications, such as preeclampsia. Monocytes differentiate into dMs in a decidua-specific microenvironment. Despite their important roles in pregnancy, the exact factors that regulate the differentiation into dMs remain unclear. Glycodelin-A (PAEP, hereafter referred to as GdA) is a glycoprotein that is abundantly present in the decidua, and plays an important role in fetomaternal defense and placental development. It modulates the differentiation and activity of several immune cell types residing in the decidua. In this study, we demonstrated that GdA induces the differentiation of human monocytes into dM-like phenotypes in terms of transcriptome, cell surface marker expression, secretome, and regulation of trophoblast and endothelial cell functions. We found that Sialic acid-binding Ig-like lectin 7 (Siglec-7) mediates the binding and biological actions of GdA in a sialic acid-dependent manner. We, therefore, suggest that GdA, induces the polarization of monocytes into dMs to regulate fetomaternal tolerance and placental development.

Glycodelin-A stimulates the conversion of human peripheral blood CD16-CD56bright NK cell to a decidual NK cell-like phenotype

STUDY QUESTION

Does glycodelin-A (GdA) induce conversion of human peripheral blood CD16-CD56bright natural killer (NK) cells to decidual NK (dNK) cells to facilitate placentation?

SUMMARY ANSWER

GdA binds to blood CD16-CD56bright NK cells via its sialylated glycans and converts them to a dNK-like cells, which in turn regulate endothelial cell angiogenesis and trophoblast invasion via vascular endothelial growth factor (VEGF) and insulin-like growth factor-binding protein 1 (IGFBP-1) secretion, respectively.

WHAT IS KNOWN ALREADY

dNK cells are the most abundant leucocyte population in the decidua. These cells express CD16-CD56bright phenotype. Peripheral blood CD16-CD56bright NK cells and hematopoietic precursors have been suggested to be capable of differentiating towards dNK cells upon exposure to the decidual microenvironment. These cells regulate trophoblast invasion during spiral arteries remodelling and mediate homoeostasis and functions of the endothelial cells. GdA is an abundant glycoprotein in the human decidua with peak expression between the 6th and 12th week of gestation, suggesting a role in early pregnancy. Indeed, GdA interacts with and modulates functions and differentiation of trophoblast and immune cells in the human feto-maternal interface. Aberrant GdA expression during pregnancy is associated with unexplained infertility, pregnancy loss and pre-eclampsia.

STUDY DESIGN, SIZE, DURATION

CD16+CD56dim, CD16-CD56bright and dNK cells were isolated from human peripheral blood and decidua tissue, respectively, by immuno-magnetic beads or fluorescence-activated cell sorting. Human extravillous trophoblasts were isolated from first trimester placental tissue after termination of pregnancy. Biological activities of the cells were studied after treatment with GdA at a physiological dose of 5 μg/mL. GdA was purified from human amniotic fluid by immuno-affinity chromatography.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Expression of VEGF, CD9, CD49a, CD151 and CD158a in the cells were determined by flow cytometry. Angiogenic proteins in the spent media of NK cells were determined by cytokine array and ELISA. Blocking antibodies were used to study the functions of the identified angiogenic proteins. Endothelial cell angiogenesis was determined by tube formation and trans-well migration assays. Cell invasion and migration were determined by trans-well invasion/migration assay. Binding of normal and de-sialylated GdA, and expression of L-selectin and siglec-7 on the NK cells were analysed by flow cytometry. The association between GdA and L-selectin on NK cells was confirmed by immunoprecipitation. Extracellular signal-regulated protein kinases (ERK) activation was determined by Western blotting and functional assays.

MAIN RESULTS AND THE ROLE OF CHANCE

GdA treatment enhanced the expression of dNK cell markers CD9 and CD49a and the production of the functional dNK secretory product VEGF in the peripheral blood CD16-CD56bright NK cells. The spent media of GdA-treated CD16-CD56bright NK cells promoted tube formation of human umbilical vein endothelial cells and invasiveness of trophoblasts. These stimulatory effects were mediated by the stimulatory activities of GdA on an ERK-activation dependent production of VEGF and IGFBP-1 by the NK cells. GdA had a stronger binding affinity to the CD16-CD56bright NK cells as compared to the CD16+CD56dim NK cells. This GdA-NK cell interaction was reduced by de-sialylation. GdA interacted with L-selectin, expressed only in the CD16-CD56bright NK cells, but not in the CD16+CD56dim NK cells. Anti-L-selectin functional blocking antibody suppressed the binding and biological activities of GdA on the NK cells.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Some of the above findings are based on a small sample size of peripheral blood CD16-CD56bright NK cells. These results need to be confirmed with human primary dNK cells.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study on the biological role of GdA on conversion of CD16-CD56bright NK cells to dNK-like cells. Further investigation on the glycosylation and functions of GdA will enhance our understanding on human placentation and placenta-associated complications with altered NK cell biology.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Hong Kong Research Grant Council Grant 17122415, Sanming Project of Medicine in Shenzhen, the Finnish Cancer Foundation, Sigrid Jusélius Foundation and the Finnish Society of Clinical Chemistry. The authors have no competing interests to declare.

Organoids of Human Endometrium: A Powerful In Vitro Model for the Endometrium-Embryo Cross-Talk at the Implantation Site

Embryo implantation has been defined as the “black box” of human reproduction. Most of the knowledge on mechanisms underlining this process derives from animal models, but they cannot always be translated to humans. Therefore, the development of an in vitro/ex vivo model recapitulating as closely and precisely as possible the fundamental functional features of the human endometrial tissue is very much desirable. Here, we have validated endometrial organoids as a suitable 3D-model to studying epithelial endometrial interface for embryo implantation. Transmission and scanning electron microscopy analyses showed that organoids preserve the glandular organization and cell ultrastructural characteristics. They also retain the responsiveness to hormonal treatment specific to the corresponding phase of the menstrual cycle, mimicking the in vivo glandular-like aspect and functions. Noteworthy, organoids mirroring the early secretive phase show the development of pinopodes, large cytoplasmic apical protrusions of the epithelial cells, traditionally considered as reliable key features of the implantation window. Moreover, organoids express glycodelin A (GdA), a cycle-dependent marker of the endometrial receptivity, with its quantitative and qualitative features accounting well for the profile detected in the endometrium in vivo. Accordingly, organoids deriving from the eutopic endometrium of women with endometriosis show a GdA glycosylation pattern significantly different from healthy organoids, confirming our prior data on endometrial tissues. The present results strongly support the idea that organoids may closely recapitulate the molecular and functional characteristics of their cells/tissue of origin.

Glycodelin is internalized by peripheral monocytes

Glycodelin is produced by the endometrial cells during the luteal phase and first trimester of pregnancy and plays a role in the regulation of the endometrial immunology. However, the molecular connection between glycodelin and the maternal immune system is not clear. To better understand the possible physiological interaction between the endometrium and the maternal immune system, we investigated (1) whether glycodelin binds to mainly peripheral monocytes, and in case (2) whether the binding to the membrane only depends on the protein backbone or a carbohydrate structure is needed, and in case (3) whether glycodelin is internalized after binding to the membrane. We demonstrated that glycodelin - with or without the carbohydrate structure - was preferentially bound and internalized to peripheral monocytes. Surprisingly, we found signals in the nucleus of the monocytes indicating a potential regulating effect of glycodelin may be exerted through the nucleus. However, further studies should be performed to confirm this finding.

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 content of immunomodulatory glycoepitopes in seminal plasma glycoproteins of fertile and infertile men

According to a concept of fetoembryonic defence, protein-carbohydrate interaction may be involved in the regulation of maternal immunity that prevents rejection of allograft spermatozoa, embryo and fetus. In the present study we focussed on the evaluation of the expression of glycoepitopes that may be of crucial importance in this process: LewisY (LeY) and LewisX (LeX) as well as terminal sialylation. Polyacrylamide gel electrophoresis with sodium dodecyl sulphate was used to separate seminal plasma samples of fertile (n=10) and infertile (n=103) men; these were then probed with lectins specific to fucose (Lotus tetragonolobus agglutinin and Ulex europaeus agglutinin) and sialic acid (Sambucus nigra agglutinin and Maackia amurensis agglutinin). Differential expression of α2,3-bound sialic acid was found in six out of seven analysed bands, whereas differences in the other analysed glycoepitopes were found in fewer numbers of bands. Mass spectrometry analysis focussed on the identification of proteins carrying glycans with immunomodulatory epitopes, including fibronectin, lactoferrin, clusterin, zinc-α2-glycoprotein, prostate acid phosphatase and prostate-specific antigen; these should be submitted to further detailed analysis.

Post-translational modifications of seminal proteins and their importance in male fertility potential

Introduction: The seminal proteome has been shown to directly influence the male fertile potential. Post-translational modifications (PTMs) are significant changes that play a role in the biological regulation of proteins. Sperm cells are transcriptionally and translationally inactive and these modifications are essential to control protein function.Areas covered: Here we reviewed seven PTMs which importance for male reproductive function investigated in the past decade, namely S-nitrosylation and tyrosine nitration (both occurring by the action of NO), glycosylation, ubiquitination, acetylation, methylation, and SUMOylation. Since they were previously identified in human semen, we focus on their role in sperm function, as well as in physiological and pathophysiological processes which could contribute to the fertility potential. The following keywords were applied: 'post-translational modification', 'sperm', 'semen', 'seminal plasma', 'male infertility', 'nitrosylation', 'nitration', 'histone methylation', 'SUMOylation', 'ubiquitination', 'ubiquitilation', 'glycosylation', and 'acetylation'.Expert opinion: Most biological processes orchestrated by proteins require PTMs for their activation or inhibition. Most of them are dynamic and occur in mature sperm, modulating protein function, thus exerting a significant role in sperm function and fertility. Finally, the study of PTMs should be also addressed in pathophysiological processes, as different clinical conditions are known to alter the proteome.

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.

Endometrial polyps: Pathogenesis, sequelae and treatment

Endometrial polyps are overgrowths of endometrial glands that typically protrude into the uterine cavity. Endometrial polyps are benign in nature and affect both reproductive age and postmenopausal women. Although endometrial polyps are relatively common and may be accompanied by abnormally heavy bleeding at menstruation. In asymptomatic women, endometrial polyps may regress spontaneously, in symptomatic women endometrial polyps can be treated safely and efficiently with hysteroscopic excision.

Pathways regulating the expression of the immunomodulatory protein glycodelin in non‑small cell lung cancer

Glycodelin [gene name, progesterone associated endometrial protein (PAEP)] was initially described as an immune system modulator in reproduction. Today, it is also known to be expressed in several types of cancer, including non‑small cell lung cancer (NSCLC). In this cancer type, the feasibility of its usage as a follow‑up biomarker and its potential role as an immune system modulator were described. It is assumed that NSCLC tumours secrete glycodelin to overcome immune surveillance. Therefore, targeting glycodelin might be a future approach with which to weaken the immune system defence of NSCLC tumours. In this context, it is important to understand the regulatory pathways of PAEP/glycodelin expression, as these are mostly unknown so far. In this study, we analysed the influence of several inducers and of their downstream pathways on PAEP/glycodelin expression in a human lung adenocarcinoma carcinoma (ADC; H1975) and a human lung squamous cell carcinoma (SQCC) cell line (2106T). PAEP/glycodelin expression was notably stimulated by the canonical transforming growth factor (TGF)‑β pathway in SQCC cells and the PKC signalling cascade in both cell lines. The PI3K/AKT pathway inhibited PAEP/glycodelin expression in the ADC cells and an antagonizing role towards the other investigated signalling cascades is suggested herein. Furthermore, the mitogen‑activated protein kinase kinase (MEK)/extracellular‑signal regulated kinases (ERK) pathway was, to a lesser extent, found to be associated with increased PAEP/glycodelin amounts. The phosphoinositide 3‑kinase (PI3K)/protein kinase B (AKT), MEK/ERK pathway and TGF‑β are targets of NSCLC drugs that are already approved or are currently under investigation. On the whole, the findings of this study provide evidence that inhibiting these targets affects the expression of glycodelin and its immunosuppressive effect in NSCLC tumours. Moreover, understanding the regulation of glycodelin expression may lead to the development of novel therapeutic approaches with which to weaken the immune system defence of NSCLC tumours in the future.

Proteins from male and female reproductive tracts involved in sperm function regulation

Spermatogenesis is a dynamic process that culminates in the production of mature spermatozoa in the seminiferous tubules of sexually mature animals. Although sperm leaving the testis are fully differentiated, they must further undergo two additional maturation steps before acquiring the capability to fertilize the egg. Such processes take place during the epididymal residency and transport in the seminal fluid during ejaculation and, after delivery into the female reproductive tract, during the journey aiming the encountering the egg in the oviduct. Throughout this trip, spermatozoa are exposed to different reproductive fluids whose molecular compositions regulate the progress towards obtaining a fertilized competent cell. This review summarizes the evidence obtained so far supporting the participation of male and female reproductive tract-derived proteins in the modulation of sperm fertilizing ability and discusses the mechanisms by which such regulation may be accomplished.

Expression of cystatin C in the female reproductive tract and its effect on human sperm capacitation

BACKGROUND

Cystatin C (CST3), a cysteine protease inhibitor in seminal plasma, is expressed in animal uteri. However, its expression in the human female reproductive tract and its effect on human sperm capacitation are unclear.

METHODS

The cellular localization of CST3 was observed using immunohistochemistry. The binding of CST3 to sperm was examined using immunocytochemistry. Sperm motility parameters were analyzed using computer-assisted sperm analysis. Sperm capacitation was evaluated by analyzing cholesterol content, protein tyrosine phosphorylation levels, and the acrosome reaction.

RESULTS

Immunohistochemical staining demonstrated that CST3 is prominently expressed in the female reproductive tract, including the epithelial lining and cervix and endometrium fluids, particularly at times near ovulation. It can bind to human sperm on the post-acrosomal head region and the mid and principal piece of the tail. CST3 enhances sperm motility and inhibits the signal initiating sperm capacitation, i.e., efflux of cholesterol from the sperm plasma membrane and a late sperm capacitation event, i.e., the increase in the sperm protein tyrosine phosphorylation. The suppressive trend on sperm acrosome reaction further supports CST3's ability to inhibit sperm capacitation.

CONCLUSIONS

These findings suggest that cervical CST3 may prevent precocious capacitation and acrosome reaction, thus preserving sperm fertilizing ability before it reaches the fallopian tube. Additionally, CST3 may help sperm enter the upper reproductive tract by enhancing sperm motility.

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.

Improving porcine in vitro fertilization output by simulating the oviductal environment

Differences between the in vitro and in vivo environment in which fertilization occurs seem to play a key role in the low efficiency of porcine in vitro fertilization (IVF). This work proposes an IVF system based on the in vivo oviductal periovulatory environment. The combined use of an IVF medium at the pH found in the oviduct in the periovulatory stage (pH_e 8.0), a mixture of oviductal components (cumulus-oocyte complex secretions, follicular fluid and oviductal periovulatory fluid, OFCM) and a device that interposes a physical barrier between gametes (an inverted screw cap of a Falcon tube, S) was compared with the classical system at pH_e 7.4, in a 4-well multidish (W) lacking oviduct biological components. The results showed that the new IVF system reduced polyspermy and increased the final efficiency by more than 48%. This higher efficiency seems to be a direct consequence of a reduced sperm motility and lower capacitating status and it could be related to the action of OFCM components over gametes and to the increase in the sperm intracellular pH (pH_i) caused by the higher pH_e used. In conclusion, a medium at pH 8.0 supplemented with OFCM reduces polyspermy and improves porcine IVF output.

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.

N-Glycoproteomics of Human Seminal Plasma Glycoproteins

Seminal plasma aids sperm by inhibiting premature capacitation, helping in the intracervical transport and formation of an oviductal sperm reservoir, all of which appear to be important in the fertilization process. Epitopes such as Lewis x and y are known to be present on seminal plasma glycoproteins, which can modulate the maternal immune response. It is suggested by multiple studies that seminal plasma glycoproteins play, largely undiscovered, important roles in the process of fertilization. We have devised a strategy to analyze glycopeptides from a complex, unknown mixture of protease-digested proteins. This analysis provides identification of the glycoproteins, glycosylation sites, glycan compositions, and proposed structures from the original sample. This strategy has been applied to human seminal plasma total glycoproteins. We have elucidated glycan compositions and proposed structures for 243 glycopeptides belonging to 73 N-glycosylation sites on 50 glycoproteins. The majority of the proposed glycan structures were complex type (83%) followed by high-mannose (10%) and then hybrid (7%). Most of the glycoproteins were either sialylated, fucosylated, or both. Many Lewis x/a and y/b epitopes bearing glycans were found, suggesting immune-modulating epitopes on multiple seminal plasma glycoproteins. The study also shows that large scale N-glycosylation mapping is achievable with current techniques and the depth of the analysis is roughly proportional to the prefractionation and complexity of the sample.

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.

Functional glycosylation in the human and mammalian uterus

Background

Glycosylation is the most common and structurally diverse of all the post-translational modifications of proteins. Lipids and extracellular matrices are also often glycosylated. The mammalian uterus is highly enriched in glycoconjugates that are associated with the apical surfaces of epithelial cells and the secretions released by both epithelial and stromal cells. These glycoconjugates interact primarily with sperm, the implanting embryo, the fetus, and any pathogen that happens to gain entry into the uterus. Secretions of the endometrial glands increase substantially during the luteal phase of the menstrual cycle. These secretions are highly enriched in glycoproteins and mucins that promote specific uterine functions.

Findings

Lectins and antibodies have been employed in the majority of the studies focused on uterine glycosylation have employed to define the expression of carbohydrate sequences. However, while these studies provide insight about potential glycosylation, precise information about glycan structure is lacking. Direct sequencing studies that employ biochemical or mass spectrometric methods are far more definitive, but have rarely been employed with uterine glycoproteins. Both lectin/antibody binding and direct carbohydrate sequencing studies that have been focused on the mammalian uterus are reviewed. The primary functional role of the eutherian uterus is to facilitate fertilization and nurture the developing embryo/fetus. Trophoblasts are the primary cells that mediate the binding of the embryo and placenta to the uterine lining. In mammals that utilize hemochorial placentation, they invade the decidua, the specialized endometrial lining that forms during pregnancy. Trophoblasts have also been analyzed for their lectin/antibody binding as a complement to the analysis of the uterine cells and tissues. They will also be reviewed here.

Conclusions

The functional roles of the glycans linked to uterine and trophoblast glycoconjugates remain enigmatic. Another major question in the human is whether defects in placental or uterine glycosylation play a role in the development the Great Obstetrical Syndromes. More recent findings indicate that changes in glycosylation occur in trophoblasts obtained from patients that develop preeclampsia and preterm birth. The functional significance of these changes remain to be defined. Whether such shifts happen during the development of other types of obstetrical syndromes remains to be determined.

Potential causes of subfertility in patients with intramural fibroids

BACKGROUND

Intramural leiomyomas have been long debated as a potential cause of infertility and pregnancy loss.

FINDINGS

Previous research has linked intramural fibroids to defective implantation, as well as to abnormal peristaltic events of the uterine smooth muscle. Previous reports describe the effects of intramural fibroids on normal human fertility and early pregnancy loss, specifically in regards to implantation failure.

CONCLUSION

A thorough understanding of prior research may direct new research focus, leading to better understanding of leiomyoma-associated infertility.

Terminal Mannose Residues in Seminal Plasma Glycoproteins of Infertile Men Compared to Fertile Donors

The impact of seminal plasma components on the fertilization outcomes in humans is still under question. The increasing number of couples facing problems with conception raises the need for predictive biomarkers. Detailed understanding of the molecular mechanisms accompanying fertilization remains another challenge. Carbohydrate–protein recognition may be of key importance in this complex field. In this study, we analyzed the unique glycosylation pattern of seminal plasma proteins, the display of high-mannose and hybrid-type oligosaccharides, by means of their reactivity with mannose-specific Galanthus nivalis lectin. Normozoospermic infertile subjects presented decreased amounts of lectin-reactive glycoepitopes compared to fertile donors and infertile patients with abnormal semen parameters. Glycoproteins containing unveiled mannose were isolated in affinity chromatography, and 17 glycoproteins were identified in liquid chromatography-tandem mass spectrometry with electrospray ionization. The N-glycome of the isolated glycoproteins was examined in matrix-assisted laser desorption ionization mass spectrometry. Eleven out of 27 identified oligosaccharides expressed terminal mannose residues, responsible for lectin binding. We suggest that lowered content of high-mannose and hybrid type glycans in normozoospermic infertile patients may be associated with impaired sperm protection from preterm capacitation and should be considered in the search for new infertility markers.

Correlation of endometrial glycodelin expression and pregnancy outcome in cases with polycystic ovary syndrome treated with clomiphene citrate plus metformin: a controlled study

Objective. The purpose of this study was to evaluate the relationship between clomiphene citrate (CC) plus metformin treatment and endometrial glycodelin expression and to then correlate this relationship with pregnancy outcomes. Material and Methods. A total of 30 patients diagnosed with polycystic ovary syndrome (PCOS) according to the Rotterdam criteria constituted our study group. All had been admitted to the gynecology outpatient clinic between June 1, 2011, and January 1, 2012, for infertility treatment. Our control group consisted of 20 patients admitted for routine Pap smear control. They had no history of infertility and were not using contraceptives and they were actively attempting pregnancy. Midluteal progesterone measurement and pipelle endometrial biopsies were performed with both groups. For PCOS patients, metformin treatment was initiated right after the biopsy and CC was added in the second menstrual cycle. Pipelle endometrial biopsies were repeated. Histological dating and immunohistochemistry for glycodelin were performed by a single pathologist who was blinded to the patients' clinical data. Result(s). The posttreatment ovulation rate in the study group was 93.3%. No pregnancies were achieved in either group when glycodelin expression was not present, even in the presence of ovulation. When glycodelin expression was high in PCOS group, the pregnancy rate was 60% and all pregnancies ended in live births. In weak expression group, however, three out of four pregnancies ended as early pregnancy losses. Conclusion(s). Endometrial glycodelin expression is an important predictor of pregnancy outcomes in both PCOS and fertile groups.

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.

Immunosuppressive Glycodelin A is an independent marker for poor prognosis in endometrial cancer

Background

Knowledge on immunosuppressive factors in the pathogenesis of endometrial cancer is scarce. The aim of this study was to assess Glycodelin (Gd) and its immunosuppressive isoform Glycodelin A (GdA) in endometrial cancer tissue and to analyze its impact on clinical and pathological features and patient outcome.

Methods

292 patients diagnosed and treated for endometrial cancer were included. Patient characteristics, histology and follow-up data were available. Gd and GdA was determined by immunohistochemistry and in situ hybridization was performed for Gd mRNA.

Results

Endometrial cancer shows intermediate (52.2%) or high (20.6%) expression for Gd in 72.8%, and GdA in 71.6% (intermediate 62.6%, high 9.0%) of all cases. The glycosylation dependent staining of GdA is tumour specific and correlates with the peptide-specific Gd staining though neither of the two is associated with estrogen receptor, progesterone receptor or clinic-pathological features. Also Gd protein positively correlates with Gd mRNA as quantified by in situ hybridization. Gd positive cases have a favourable prognosis (p = 0.039), while GdA positive patients have a poor outcome (p = 0.003). Cox-regression analysis proofed GdA to be an independent prognostic marker for patient survival (p = 0.002), besides tumour stage, grade and the concomitant diagnosis of hypertension.

Conclusion

Gd and GdA are commonly expressed in endometrial cancer tissue and seem to be of relevance in tumourigenesis. They differ not only in glycosylation but also in their biological activity, since only GdA holds prognostic significance for a poor overall survival in endometrial cancer patients. This finding might be explained by GdAs immunosuppressive capacity.

Mapping the apoptosis inducing domain of an immunomodulatory protein: glycodelin A

Glycodelin A (GdA) is a dimeric glycoprotein synthesized by the human endometrium under progesterone regulation. Based on the high sequence similarity with β-lactoglobulin, it is placed under the lipocalin superfamily. The protein is one of the local immunomodulators present at the feto-maternal interface which affects both the innate as well as the acquired arms of the immune system, thereby bringing about successful establishment and progression of pregnancy. Our previous studies revealed that the domain responsible for the immunosuppressive activity of glycodelin lies on its protein backbone and the glycans modulate the same. This study attempts to further delineate the apoptosis inducing region of GdA. Our results demonstrate that the stretch of amino acid sequence between Met24 to Leu105 is necessary and sufficient to inhibit proliferation of T cells and induce apoptosis in them. Further, within this region the key residues involved in harboring the activity were shown to be present between Asp52 and Ser65.

Glycodelin-A stimulates interleukin-6 secretion by human monocytes and macrophages through L-selectin and the extracellular signal-regulated kinase pathway

Macrophages represent the second major type of decidual leukocytes at the fetomaternal interface. Changes in macrophage number and activity are associated with fetal loss and pregnancy complications. Glycodelin-A (GdA) is an abundant glycoprotein in the first-trimester decidua. It is involved in fetomaternal defense and early placental development through its regulatory activities in various immune cells. The N-glycosylation of GdA mediates the binding and therefore the activities of the molecule. In this study, we studied the biological activities of GdA in the functions of human monocytes/macrophages. GdA was purified from amniotic fluid by affinity chromatography. GdA treatment did not affect the viability, cell death, or phagocytic activity of the monocytes/macrophages. GdA, but not recombinant glycodelin without glycosylation, induced IL-6 production as demonstrated by cytokine array, intracellular staining, and ELISA. GdA also induced phosphorylation of ERK in monocytes/macrophages. The involvement of ERKs in IL-6 induction was confirmed using pharmacological inhibitors. Co-immunoprecipitation showed that L-selectin on the monocytes/macrophages was the binding protein of GdA. Treatment with anti-L-selectin antibody reduced GdA binding and GdA-induced IL-6 production. GdA-treated macrophages suppressed IFN-γ expression by co-cultured T-helper cells in an IL-6-dependent manner. These results show that GdA interacts with L-selectin to induce IL-6 production in monocytes/macrophages by activating the ERK signaling pathway. In turn, the increased IL-6 production suppresses IFN-γ expression in T-helper cells, which may play an important role in inducing a Th-2-polarized cytokine environment that flavors the immunotolerance of the fetoplacental unit.

Sperm preparation: state-of-the-art--physiological aspects and application of advanced sperm preparation methods

For assisted reproduction technologies (ART), numerous techniques were developed to isolate spermatozoa capable of fertilizing oocytes. While early methodologies only focused on isolating viable, motile spermatozoa, with progress of ART, particularly intracytoplasmic sperm injection (ICSI), it became clear that these parameters are insufficient for the identification of the most suitable spermatozoon for fertilization. Conventional sperm preparation techniques, namely, swim-up, density gradient centrifugation and glass wool filtration, are not efficient enough to produce sperm populations free of DNA damage, because these techniques are not physiological and not modeled on the stringent sperm selection processes taking place in the female genital tract. These processes only allow one male germ cell out of tens of millions to fuse with the oocyte. Sites of sperm selection in the female genital tract are the cervix, uterus, uterotubal junction, oviduct, cumulus oophorus and the zona pellucida. Newer strategies of sperm preparation are founded on: (i) morphological assessment by means of 'motile sperm organelle morphological examination (MSOME)'; (ii) electrical charge; and (iii) molecular binding characteristics of the sperm cell. Whereas separation methods based on electrical charge take advantage of the sperm's adherence to a test tube surface or separate in an electrophoresis, molecular binding techniques use Annexin V or hyaluronic acid (HA) as substrates. Techniques in this category are magnet-activated cell sorting, Annexin V-activated glass wool filtration, flow cytometry and picked spermatozoa for ICSI (PICSI) from HA-coated dishes and HA-containing media. Future developments may include Raman microspectrometry, confocal light absorption and scattering spectroscopic microscopy and polarization microscopy.

Human amniotic glycodelin actively regulates changes in β-catenin immunoreactivity in cultured human umbilical vein endothelial cells (HUVEC)

OBJECTIVE

Assessment of the capacity of Glycodelin A (GdA) to modulate the aggregation of cultured human umbilical vein endothelial cells.

METHODS

Highly purified Glycodelin A (GdA) from late first trimester amniotic fluid has been added to cultured cells and its biological activity has been observed with immunofluorescent staining of β-catenin molecules.

RESULTS

GdA induces translocation of β-catenin molecules promoting cell-to-cell adhesion and formation of adherents junctions through cytoskeletal reorganization.

CONCLUSION

These data provide further mechanistic insight into the specificity of cell-to-cell adhesion, thus corroborating the role of GdA in promoting angiogenesis.

Enhancing recombinant protein production in human cell lines with a constitutive transport element and mRNA export proteins

Recent research into mRNA maturation processes in the nucleus has identified a number of proteins involved in mRNA transcription, capping, splicing, end processing and export. Among them, the Tap-p15 heterodimer acts as an mRNA export receptor. Tap-p15 is recruited onto fully processed mRNA in the nucleus, which is ready for export to the cytoplasm, through associating with Aly or SR proteins on mRNA, or by directly associating with a constitutive transport element (CTE), an RNA element derived from type D retroviruses. mRNA containing a CTE is exported to the cytoplasm by directly associating with Tap-p15, even in the absence of Tap-recruiting proteins such as Aly or SR proteins on the mRNA. Here, we showed that the use of a CTE enhanced the expression of recombinant protein in human cell lines. The co-expression of reporter proteins and Tap-p15 also enhanced recombinant protein expression. Moreover, the use of a CTE and Tap-p15 synergistically further enhanced the recombinant protein expression. In addition to Tap-p15, several Tap-p15-recruiting proteins, including Aly and SR proteins, enhanced recombinant protein expression, albeit independently of the CTE. The incorporation of a CTE and Tap-p15-recruiting proteins into protein expression system is useful to increase recombinant protein yield in human cells.

Contraceptive vaccines targeting factors involved in establishment of pregnancy

Current methods of contraception lack specificity and are accompanied with serious side effects. A more specific method of contraception is needed. Contraceptive vaccines can provide most, if not all, the desired characteristics of an ideal contraceptive. This article reviews several factors involved in the establishment of pregnancy, focusing on those that are essential for successful implantation. Factors that are both essential and pregnancy-specific can provide potential targets for contraception. Using database search, 76 factors (cytokines/chemokines/growth factors/others) were identified that are involved in various steps of the establishment of pregnancy. Among these factors, three, namely chorionic gonadotropin (CG), leukemia inhibitory factor (LIF), and pre-implantation factor (PIF), are found to be unique and exciting molecules. Human CG is a well-known pregnancy-specific protein that has undergone phase I and phase II clinical trials, in women, as a contraceptive vaccine with encouraging results. LIF and PIF are pregnancy-specific and essential for successful implantation. These molecules are intriguing and may provide viable targets for immunocontraception. A multiepitope vaccine combining factors/antigens involved in various steps of the fertilization cascade and pregnancy establishment may provide a highly immunogenic and efficacious modality for contraception in humans.

Glycosylation failure extends to glycoproteins in gestational diabetes mellitus: evidence from reduced α2-6 sialylation and impaired immunomodulatory activities of pregnancy-related glycodelin-A

OBJECTIVE

Gestational diabetes mellitus (GDM) is a common metabolic disorder of pregnancy. Patients with GDM are at risk for high fetal mortality and gestational complications associated with reduced immune tolerance and abnormal carbohydrate metabolism. Glycodelin-A (GdA) is an abundant decidual glycoprotein with glycosylation-dependent immunomodulatory activities. We hypothesized that aberrant carbohydrate metabolism in GDM was associated with changes in glycosylation of GdA, leading to defective immunomodulatory activities.

RESEARCH DESIGN AND METHODS

GdA in the amniotic fluid from women with normal (NGdA) and GDM (DGdA) pregnancies was purified by affinity chromatography. Structural analysis of protein glycosylation was preformed by lectin-binding assay and mass spectrometry. Cytotoxicity, cell death, cytokine secretion, and GdA binding of the GdA-treated lymphocytes and natural killer (NK) cells were determined. The sialidase activity in the placental tissue from normal and GDM patients was measured.

RESULTS

GDM affected the glycosylation but not the protein core of GdA. Specifically, DGdA had a lower abundance of α2-6-sialylated and high-mannose glycans and a higher abundance of glycans with Sda (NeuAcα2-3[GalNAcβ1-4]Gal) epitopes compared with NGdA. DGdA had reduced immuosuppressive activities in terms of cytotoxicity on lymphocytes, inhibitory activities on interleukin (IL)-2 secretion by lymphocytes, stimulatory activities on IL-6 secretion by NK cells, and binding to these cells. Desialylation abolished the immunomodulation and binding of NGdA. Placental sialidase activity was increased in GDM patients, which may account for the reduced sialic acid content of DGdA.

CONCLUSIONS

Taken together, this study provides the first direct evidence for altered enzymatic glycosylation and impaired bioactivity of GdA in GDM patients.

Differential actions of glycodelin-A on Th-1 and Th-2 cells: a paracrine mechanism that could produce the Th-2 dominant environment during pregnancy

BACKGROUND

The maternal-fetal interface has a unique immunological response towards the implanting placenta. It is generally accepted that a T-helper type-2 (Th-2) cytokine prevailing environment is important in pregnancy. The proportion of Th-2 cells in the peripheral blood and decidua is significantly higher in pregnant women in the first trimester than in non-pregnant women. Glycodelin-A (GdA) is a major endocrine-regulated decidual glycoprotein thought to be related to fetomaternal defence. Yet the relationship between its immunoregulatory activities and the shift towards Th-2 cytokine profile during pregnancy is unclear.

METHODS

GdA was immunoaffinity purified from human amniotic fluid. T-helper, T-helper type-1 (Th-1) and Th-2 cells were isolated from the peripheral blood. The viability of these cells was studied by XTT assay. Immunophenotyping of CD4/CD294, cell death and GdA-binding were determined by flow cytometry. The mRNA expression, surface expression and secretion of Fas/Fas ligand (FasL) were determined by quantitative polymerase chain reaction, flow cytometry and ELISA, respectively. The activities of caspase-3, -8 and -9 were measured. The phosphorylation of extracellular signal-regulated kinases (ERK), p38 and, c-Jun N-terminal kinase was determined by western blotting.

RESULTS

Although GdA bound to both Th-1 and Th-2 cells, it had differential actions on the two cell-types. GdA induced cell death of the Th-1 cells but not the Th-2 cells. The cell death was mediated through activation of caspase -3, -8 and -9 activities. GdA up-regulated the expression of Fas and inhibited ERK activation in the Th-1 cells, which might enhance the vulnerability of the cells to cell death caused by a trophoblast-derived FasL.

CONCLUSIONS

The data suggest that GdA could be an endometrial factor that contributes to the Th-2/Th-1 shift during pregnancy.