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

Cryo-electron microscopy for GPCR research and drug discovery in endocrinology and metabolism

G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors, with many GPCRs having crucial roles in endocrinology and metabolism. Cryogenic electron microscopy (cryo-EM) has revolutionized the field of structural biology, particularly regarding GPCRs, over the past decade. Since the first pair of GPCR structures resolved by cryo-EM were published in 2017, the number of GPCR structures resolved by cryo-EM has surpassed the number resolved by X-ray crystallography by 30%, reaching >650, and the number has doubled every ~0.63 years for the past 6 years. At this pace, it is predicted that the structure of 90% of all human GPCRs will be completed within the next 5-7 years. This Review highlights the general structural features and principles that guide GPCR ligand recognition, receptor activation, G protein coupling, arrestin recruitment and regulation by GPCR kinases. The Review also highlights the diversity of GPCR allosteric binding sites and how allosteric ligands could dictate biased signalling that is selective for a G protein pathway or an arrestin pathway. Finally, the authors use the examples of glycoprotein hormone receptors and glucagon-like peptide 1 receptor to illustrate the effect of cryo-EM on understanding GPCR biology in endocrinology and metabolism, as well as on GPCR-related endocrine diseases and drug discovery.

Decreased Expression of Placental Proteins in Recurrent Pregnancy Loss: Functional Relevance and Diagnostic Value

Miscarriages affect 50-70% of all conceptions and 15-20% of clinically recognized pregnancies. Recurrent pregnancy loss (RPL, ≥2 miscarriages) affects 1-5% of recognized pregnancies. Nevertheless, our knowledge about the etiologies and pathophysiology of RPL is incomplete, and thus, reliable diagnostic/preventive tools are not yet available. Here, we aimed to define the diagnostic value of three placental proteins for RPL: human chorionic gonadotropin free beta-subunit (free-β-hCG), pregnancy-associated plasma protein-A (PAPP-A), and placental growth factor (PlGF). Blood samples were collected from women with RPL (n = 14) and controls undergoing elective termination of pregnancy (n = 30) at the time of surgery. Maternal serum protein concentrations were measured by BRAHMS KRYPTOR Analyzer. Daily multiple of median (dMoM) values were calculated for gestational age-specific normalization. To obtain classifiers, logistic regression analysis was performed, and ROC curves were calculated. There were differences in changes of maternal serum protein concentrations with advancing healthy gestation. Between 6 and 13 weeks, women with RPL had lower concentrations and dMoMs of free β-hCG, PAPP-A, and PlGF than controls. PAPP-A dMoM had the best discriminative properties (AUC = 0.880). Between 9 and 13 weeks, discriminative properties of all protein dMoMs were excellent (free β-hCG: AUC = 0.975; PAPP-A: AUC = 0.998; PlGF: AUC = 0.924). In conclusion, free-β-hCG and PAPP-A are valuable biomarkers for RPL, especially between 9 and 13 weeks. Their decreased concentrations indicate the deterioration of placental functions, while lower PlGF levels indicate problems with placental angiogenesis after 9 weeks.

Expression of placental glycans and its role in regulating peripheral blood NK cells during preeclampsia: a perspective

Preeclampsia is a pregnancy-related multisystem disorder characterized by altered trophoblast invasion, oxidative stress, exacerbation of systemic inflammatory response, and endothelial damage. The pathogenesis includes hypertension and mild-to-severe microangiopathy in the kidney, liver, placenta, and brain. The main mechanisms involved in its pathogenesis have been proposed to limit trophoblast invasion and increase the release of extracellular vesicles from the syncytiotrophoblast into the maternal circulation, exacerbating the systemic inflammatory response. The placenta expresses glycans as part of its development and maternal immune tolerance during gestation. The expression profile of glycans at the maternal-fetal interface may play a fundamental role in physiological pregnancy changes and disorders such as preeclampsia. It is unclear whether glycans and their lectin-like receptors are involved in the mechanisms of maternal-fetal recognition by immune cells during pregnancy homeostasis. The expression profile of glycans appears to be altered in hypertensive disorders of pregnancy, which could lead to alterations in the placental microenvironment and vascular endothelium in pregnancy conditions such as preeclampsia. Glycans with immunomodulatory properties at the maternal-fetal interface are altered in early-onset severe preeclampsia, implying that innate immune system components, such as NK cells, exacerbate the systemic inflammatory response observed in preeclampsia. In this article, we discuss the evidence for the role of glycans in gestational physiology and the perspective of glycobiology on the pathophysiology of hypertensive disorders in gestation.

The Involvement of Cell Adhesion Molecules, Tight Junctions, and Gap Junctions in Human Placentation

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

Differential gene expression in bovine endometrial epithelial cells after challenge with LPS; specific implications for genes involved in embryo maternal interactions

Lipopolysaccharide (LPS) expressed on the surface of Gram-negative bacteria activates pro-inflammatory pathways, dys-regulates the function of endometrial cells and is a key player in the mechanisms involved in endometritis. This study aimed to investigate the effects of LPS on bovine endometrial epithelial cells (bEEC) from whole transcriptome with a special focus on genes involved in embryo-maternal interactions. Following in vitro culture, bEEC from three cows were exposed to 0, 2, and 8 μg/mL LPS for 24h. RNA samples extracted at 0 and 24 hours were analyzed by RNA sequencing (RNA-seq). At 24h, 2035 differentially expressed genes (DEGs) were identified between controls and samples treated with 2 μg/mL LPS. Gene ontology analysis showed that over-expressed DEGs were associated to immune response, response to stress and external stimuli, catalytic activity, and cell cycle. Genes associated with cell membrane and cell adhesion pathways were under-expressed. LPS induced changes in expression of specific genes related to embryo-maternal interactions including under-expression of eight members of the cadherin superfamily, over-expression of six members of the mucin family, and differential expression of a large set of genes binding the above molecules and of more than 20 transcripts coding for cytokines and their receptors. Type I interferon-τ dependent genes were also over-expressed. From a sub-set of 19 genes, (biological replicates of bEEC from cows taken at time 6 (n = 3), 24 (n = 6) and 48 hours (n = 3), and 2 technical replicates per sample) differential gene expression was confirmed by RT²-qPCR (r² between fold changes at 24 hours by RT²-qPCR and RNA-seq = 0.97). These results indicate that LPS affects the function of bEEC in many ways by differential transcription, glycolytic metabolism and oxidative stress. Many transcriptomic signatures related to implantation and embryo maternal interactions were strongly affected by LPS. These results pave the way for further studies to investigate the duration of these changes and their possible impact on endometrial function and fertility.

Changes in protein expression profiles in bovine endometrial epithelial cells exposed to E. coli LPS challenge

E. coli is one of the most frequently involved bacteria in uterine diseases. Lipopolysaccharide (LPS) is a component of the outer membrane of Gram-negative bacteria involved in pathogenic processes leading to post-partum metritis and endometritis in cattle. It also causes inflammation of the endometrium. The increase of cell proliferation by LPS is part of the inflammatory process. The aim of this study was to investigate possible changes in protein expression in relation to the proliferative response of bEECs after challenge with E. coli-LPS. In vitro culture of bEECs was performed from cow genital tracts collected at a slaughterhouse. In passage 5, bEECs from each of 9 cows (3 series of 3 cows) were exposed to 0, 8, and 16 μg ml^-1 LPS for 72 h. At time 0 and 72 h later, attached cells/living cells were counted and for each time and LPS dosage, cells were frozen for proteomic analyses. All samples from the 3 series were analyzed by 2-D gel electrophoresis coupled to MALDI-TOF/TOF mass spectrometry. The samples from the first series were subjected to shotgun nLC-MS/MS analysis. From the whole differential proteomics analysis, 38 proteins were differentially expressed (p < 0.05 to p < 0.001) following exposure to LPS. Among them, twenty-eight were found to be up-regulated in the LPS groups in comparison to control groups and ten were down-regulated. Differentially expressed proteins were associated with cell proliferation and apoptosis, transcription, destabilization of cell structure, oxidative stress, regulation of histones, allergy and general cell metabolism pathways. The de-regulations induced by LPS were consistent with the proliferative phenotype and indicated strong alterations of several cell functions. In addition, some of the differentially expressed proteins relates to pathways activated at the time of implantation. The specific changes induced through those signals may have negative consequences for the establishment of pregnancy.

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

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

The role of CX3CL1 in fetal-maternal interaction during human gestation

Embryo implantation and subsequent placentation require a fine balanced fetal-maternal cross-talk of hormones, cytokines and chemokines. Amongst the group of chemokines, CX3CL1 (also known as fractalkine) has recently attracted attention in the field of reproductive research. It exists both as membrane-bound and soluble isoforms. On the basis of current experimental evidence, fractalkine is suggested to regulate adhesion and migration processes in fetal-maternal interaction at different stages of human pregnancy. Expressed by uterine glandular epithelial cells, predominantly during the mid-secretory phase of the menstrual cycle, fractalkine appears to prime the blastocyst for forthcoming implantation. After implantation, fractalkine is suggested to regulate invasion of extravillous trophoblasts by altering their expression profile of adhesion molecules. With onset of perfusion of the intervillous space at the end of first trimester, fractalkine present at the apical microvillous plasma membrane of the syncytiotrophoblast may mediate close interaction of placental villi with circulating maternal blood cells.

Differential Spatiotemporal Patterns of Galectin Expression are a Hallmark of Endotheliochorial Placentation

PROBLEM

Galectins influence the progress of pregnancy by regulating key processes associated with embryo-maternal cross talk, including angiogenesis and placentation. Galectin family members exert multiple roles in the context of hemochorial and epitheliochorial placentation; however, the galectin prolife in endotheliochorial placenta remains to be investigated.

METHOD OF STUDY

Here, we used immunohistochemistry to analyze galectin (gal)-1, gal-3 and gal-9 expression during early and late endotheliochorial placentation in two different species (dogs and cats).

RESULTS

We found that during early feline gestation, all three galectin members were more strongly expressed on trophoblast and maternal vessels compared to the decidua. This was accompanied by an overall decrease of gal-1, gal-3 and gal-9 expressions in late feline gestation. In canine early pregnancy, we observed that gal-1 and gal-9 were expressed strongly in cytotrophoblast (CTB) cells compared to gal-3, and no galectin expression was observed in syncytiotrophoblast (STB) cells. Progression of canine gestation was accompanied by increased gal-1 and gal-3 expressions on STB cells, whereas gal-9 expression remained similar in CTB and STB.

CONCLUSION

These data suggest that both the maternal and fetal compartments are characterized by a spatiotemporal regulation of galectin expression during endotheliochorial placentation. This strongly suggests the involvement of the galectin family in important developmental processes during gestation including immunemodulation, trophoblast invasion and angiogenesis. A conserved functional role for galectins during mammalian placental development emerges from these studies.

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

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

Altered β1,6-GlcNAc and bisecting GlcNAc-branched N-glycan on integrin β1 are associated with early spontaneous miscarriage in humans

STUDY QUESTION

Do N-acetylglucosaminyltransferase (GnT-V) and N-acetylglucosaminyltransferase III (GnT-III) play an important role in early spontaneous miscarriage (ESM) in humans.

SUMMARY ANSWER

The dynamic balance between GnT-V and GnT-III expression in chorionic villi differed between early normal pregnancy and ESM and was associated with altered β1,6-N-acetylglucosamine (β1,6-GlcNAc) and bisecting N-acetylglucosamine (bis-GlcNAc) branched N-glycans on integrin β1.

WHAT IS KNOWN ALREADY

GnT-V contributes to metastasis, while GnT-III is recognized as a metastasis suppressor. It has been reported that GnT-V contributes to placentation in the early phase of pregnancy, possibly regulating trophoblast invasion. However, the expressions of GnT-V and GnT-III in ESM have not been reported.

STUDY DESIGN, SIZE, DURATION

Villous samples from 6 to 9 weeks of gestation were collected in the First Affiliated Hospital of Chongqing Medical University from May 2013 to September 2014 from 60 normal pregnant women undergoing elective termination of pregnancy and from 40 patients with a clinical diagnosis of ESM.

PARTICIPANTS, MATERIALS, SETTING, METHODS

Quantitative PCR and western blots were used to examine the GnT-V and GnT-III mRNA (Mgat5 and Mgat3) and protein expression, respectively, of chorionic villi in both the ESM group and the normal group from week 6 to week 9. We used immunofluorescence and immunohistochemistry to detect the location of GnT-V and GnT-III. Lectin fluorescence and histochemistry were used to test the location of β1,6-GlcNAc and bis-GlcNAc branching in the normal and ESM groups. To assess the functional capacity of GnT-V and GnT-III in the chorionic villi between the two groups, we used an enzyme-linked immunosorbent assay kit to measure the activity of these enzymes. Using co-precipitated integrin α5β1 followed by phytohaemagglutinin (PHA)-L and PHA-E blotting, we investigated whether GnT-V and GnT-III could modify the N-glycosylation profile in terms of the β1,6-GlcNAc and bis-GlcNAc structures in integrin α5β1 during the first trimester in both groups.

MAIN RESULTS AND THE ROLE OF CHANCE

In the normal group expression and activity of GnT-V and the concentration of its product, β1,6-GlcNAc were higher at week 9 than at weeks 6, 7 and 8 (P < 0.05). In contrast, the expression and activity of GnT-III and the concentration of its product, bis-GlcNAc were higher at week 6 than at weeks 7, 8 and 9 (P < 0.05). Compared with the normal group, the ESM group exhibited a lower expression of GnT-V and β1,6-GlcNAc (P < 0.05) and a higher expression of GnT-III and bis-GlcNAc (P < 0.05) with consistent changes in enzymatic activity. Immunofluorescence showed that GnT-V was located mainly in the cytoplasm of syncytiotrophoblasts (STBs) and chorionic villous cytotrophoblasts (CTBs), in both the ESM group and the normal group. β1,6-GlcNAc N-glycan was mainly located outside of the STB and CTB layer in normal villi and was expressed only rarely in the ESM villi. GnT-III was expressed primarily in the cytoplasm of STBs and expressed only very weakly in the CTBs of normal villi, whereas it was highly expressed in both the STBs and CTBs in the ESM group. bis-GlcNAc was primarily located outside of the STBs in the normal villi, whereas it was expressed much more abundantly outside of both the STBs and CTBs in the ESM group at each week of gestation. Moreover, decreased β1,6-GlcNAc-branched N-glycans and increased bis-GlcNAc-branched N-glycans on integrin β1 (P < 0.05) were observed in the ESM group.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings provide a new insight for studying the mechanism of clinical ESM in humans and it might be valuable for the clinical diagnosis and treatment of ESM.

LIMITATIONS, REASONS FOR CAUTION

The study lacks experiments in vitro to disclose the precise mechanism by which GnT-V and GnT-III regulate ESM. In some cases, degradation of the tissues after the miscarriage event cannot be ruled out.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by grants from the National Natural Science Foundation of China (31271546). The authors have no competing interests.

Galectin-1 overexpression in endometriosis and its regulation by neuropeptides (CRH, UCN) indicating its important role in reproduction and inflammation

Endometriosis is an inflammatory disease of women of reproductive age featured by the presence of ectopic endometrium and is strongly related to infertility. Galectins, carbonhydrate-binding proteins, have been found to have pro- or anti-inflammatory roles in the reproductive tract and in pathological conditions concerning infertility. Galectin-1, which is expressed at endometrium and decidua, plays a major role in implantation and trophoblast invasion. Also, the neuropeptides, corticotropin releasing hormone (CRH) and urocortin (UCN) and their receptors are expressed in eutopic and ectopic endometrium showing a differential expression pattern in endometriotic women compared to healthy ones. The aim of this study was to examine the galectin-1 expression in endometriotic lesions and compare its expression in eutopic endometrium of endometriotic and healthy women. Furthermore, we examined the effect of CRH and UCN in galectin-1 expression in Ishikawa cell line and macrophages and investigated the implication of CRHR1 in these responses. Eutopic and ectopic endometrium specimens, Ishikawa cell line and mice macrophages were used. Immunohistochemistry and western blot analysis were performed in order to identify galectin-1 expression in ectopic and eutopic endometrium of women with and without endometriosis and the regulatory effect of CRH and UCN on galectin-1 expression. This study presents for the first time that galectin-1 is overexpressed in endometriotic lesions compared to eutopic endometrium of endometriotic women and is more abundantly expressed in eutopic endometrium of disease women compared to healthy ones. Furthermore, it is shown that CRH and UCN upregulate galectin-1 expression in Ishikawa cell line and macrophages and this effect is mediated through CRHR1. These results suggest that galectin-1 might play an important role in endometriosis pathology and infertility profile of women suffering from endometriosis by being at the same time regulated by CRH and UCN interfering in the immune disequilibrium which characterizes this pathological condition.

Metalloprotease dependent release of placenta derived fractalkine

The chemokine fractalkine is considered as unique since it exists both as membrane-bound adhesion molecule and as shed soluble chemoattractant. Here the hypothesis was tested whether placental fractalkine can be shed and released into the maternal circulation. Immunohistochemical staining of human first trimester and term placenta sections localized fractalkine at the apical microvillous plasma membrane of the syncytiotrophoblast. Gene expression analysis revealed abundant upregulation in placental fractalkine at term, compared to first trimester. Fractalkine expression and release were detected in the trophoblast cell line BeWo, in primary term trophoblasts and placental explants. Incubation of BeWo cells and placental explants with metalloprotease inhibitor Batimastat inhibited the release of soluble fractalkine and at the same time increased the membrane-bound form. These results demonstrate that human placenta is a source for fractalkine, which is expressed in the syncytiotrophoblast and can be released into the maternal circulation by constitutive metalloprotease dependent shedding. Increased expression and release of placental fractalkine may contribute to low grade systemic inflammatory responses in third trimester of normal pregnancy. Aberrant placental metalloprotease activity may not only affect the release of placenta derived fractalkine but may at the same time affect the abundance of the membrane-bound form of the chemokine.

Intermediate filament proteins expression and carbohydrate moieties in trophoblast and decidual cells of mature cat placenta

The aim of this study was to characterize cytoskeletal intermediate filament proteins and glycoconjugates of syncytiotrophoblast, cytotrophoblast and decidual cells of feline endotheliochorial placenta. Samples from 12 normal pregnant female cats, after 45 ± 5 days of gestation, were obtained removing the uterine horns by hysterectomy. Sections were processed for routine observation and for immunohistochemistry using anticytokeratin, antivimentin and antidesmin antibodies. In addition, lectin histochemistry was performed using a panel of several biotinylated lectins to characterize glycosides expression profile. Cytotrophoblast and syncytiotrophoblast showed immunoreactivity only with acidic and basic cytokeratins. Decidual cells were only positive to vimentin, consistent with their origin from endometrial fibroblasts. Trophoblast expressed a broad population of glycans, highly exposing terminal N-acetyl glucosamine residues and non-sialylated galactose and N-acetyl galactosamine oligomers. Oligosaccharides bound by Phaseolus vulgaris erythroagglutinin were the only highly branched N-linked residues evidenced in cats, and they were restricted to the syncytium. Unlike results reported on humans, mice and rats on lectin affinity of decidual cells, sialid acids and complex N-linked oligosaccharides were not demonstrated in cats. Glycosylation of proteins determines many of their final properties, thus becoming essential for the embryo-maternal dialogue during implantation and placentation. Changes in glycosylation pattern have been related to pathological pregnancies in other species. Hence, the knowledge about glycosylation profile of the normal cat placenta may lead to a better understanding of both normal and pathological reproductive events.

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.

First trimester hyperglycosylated human chorionic gonadotrophin in serum - a marker of early-onset preeclampsia

INTRODUCTION

Recent studies indicate that treatment with low-dose aspirin may reduce the risk of preeclampsia. Thus, early prediction of preeclampsia is needed. Low serum concentrations of hyperglycosylated human chorionic gonadotrophin (hCG-h) are associated with early pregnancy loss. We therefore studied whether it may serve as an early marker of preeclampsia.

METHODS

A nested case-control study included 158 women with subsequent preeclampsia, 41 with gestational hypertension, 81 normotensive women giving birth to small-for-gestational-age (SGA) infants and 427 controls participating in first trimester screening for Down's syndrome between 8 and 13 weeks of gestation. Gestational-age-adjusted multiples of medians (MoMs) were calculated for serum concentrations of hCG-h, the free beta subunit of hCG (hCGβ) and pregnancy-associated plasma placental protein A (PAPP-A) and the proportion of hCG-h to hCG (%hCG-h). Clinical risk factors including mean arterial pressure (MAP) and parity were also included in the risk calculation.

RESULTS

In women with subsequent preeclampsia %hCG-h was lower than in controls (median MoM 0.92, P < 0.001), especially in 29 cases with early-onset preeclampsia (0.86, P < 0.001), in which PAPP-A also was reduced (0.95, P = 0.001). At 90% specificity for prediction of early-onset preeclampsia, sensitivity was 56% (95% confidence interval, 52-61%) for %hCG-h, 33% (28-37%) for PAPP-A, and 69% (51-83%) for the combination of these with first trimester MAP and parity. The area under the receiver-operating characteristic (ROC) curve for the combination of all these was 0.863 (0.791-0.935).

CONCLUSIONS

hCG-h is a promising first trimester marker for early-onset preeclampsia. Addition of PAPP-A and maternal risk factors may improve the results.

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

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

Adaptive immune responses during pregnancy

It has long been believed that there is no immune interaction between mother and conceptus during pregnancy. This concept changed after evidence was provided that the maternal immune system is aware of the semiallogeneic conceptus and develops strategies to tolerate it. Since then, finely regulated mechanisms of active tolerance toward the fetus have been described. This Special Issue of the American Journal of Reproductive Immunology deals with these mechanisms. It begins with the description of minor histocompatibility antigens in the placenta; it further goes through adaptive immune responses toward paternal fetal antigens, mostly concentrating on regulatory T cells and molecules modulating the Th1/Th2 balance. The participation of antibody-producing B cells in normal and pathological pregnancies is also discussed. This introductory chapter resumes the concepts presented throughout the Issue and discusses the clinical applications raised from these concepts.

Lectin-based analysis of fucose and sialic acid expressions on human amniotic IgA during normal pregnancy

The sugar moiety of IgA is known to provide a link between the innate and adaptive immune systems. Terminally located glycotopes on IgA are potential ligands engaged in the interactions which may modulate the biological activities of IgA. In the present work the expressions of Maackia amurensis (MAA), Sambucus nigra (SNA), Lens culinaris (LCA), Tetragonolobus purpureus (LTA), and Ulex europaeus (UEA) reactive glycotopes on maternal plasma and amniotic IgA were evaluated in relation to the progression of a normal human pregnancy, from the 2nd trimester, throughout the 3rd trimester, perinatal period, post-date pregnancy and delivery, by lectin-IgA-ELISA, using specific biotinylated lectins. The amniotic and maternal plasma IgA concentrations and a degree of SNA and LCA reactivity of maternal plasma IgA were almost unaltered during the normal pregnancy. The amniotic IgA from the 2nd trimester was decorated by MAA-, SNA-reactive and LCA-, LTA-, and UEA-reactive glycotopes. At the turn of the 2nd and 3rd trimesters the expression of MAA-, SNA-, LTA-, and UEA-reactive glycotopes, except for LCA-reactive, increased and remained almost at unaltered levels throughout the perinatal period and delivery. However, in the post-date pregnancy the expression of LCA-, LTA-, and UEA-reactive and SNA-reactive glycotopes were significantly higher. The unique fucosylated and sialylated glycovariants of amniotic IgA associated with the progression of the normal pregnancy may illustrate a general importance of carbohydrate-lectin receptor interactions in the control and modulation of biological events to ensuring homeostasis during pregnancy, protection and well-being of fetus.

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.

Galectin-1 influences trophoblast immune evasion and emerges as a predictive factor for the outcome of pregnancy

Galectin-1 (gal-1) is expressed at the feto-maternal interface and plays a role in regulating the maternal immune response against placental alloantigens, contributing to pregnancy maintenance. Both decidua and placenta contribute to gal-1 expression and may be important for the maternal immune regulation. The expression of gal-1 within the placenta is considered relevant to cell-adhesion and invasion of trophoblasts, but the role of gal-1 in the immune evasion machinery exhibited by trophoblast cells remains to be elucidated. In this study, we analyzed gal-1 expression in preimplantation human embryos and first-trimester decidua-placenta specimens and serum gal-1 levels to investigate the physiological role played by this lectin during pregnancy. The effect on human leukocyte antigen G (HLA-G) expression in response to stimulation or silencing of gal-1 was also determined in the human invasive, proliferative extravillous cytotrophoblast 65 (HIPEC65) cell line. Compared with normal pregnant women, circulating gal-1 levels were significantly decreased in patients who subsequently suffered a miscarriage. Human embryos undergoing preimplantation development expressed gal-1 on the trophectoderm and inner cell mass. Furthermore, our in vitro experiments showed that exogenous gal-1 positively regulated the membrane-bound HLA-G isoforms (HLA-G1 and G2) in HIPEC65 cells, whereas endogenous gal-1 also induced expression of the soluble isoforms (HLA-G5 and -G6). Our results suggest that gal-1 plays a key role in pregnancy maternal immune regulation by modulating HLA-G expression on trophoblast cells. Circulating gal-1 levels could serve as a predictive factor for pregnancy success in early human gestation.

Human chorionic gonadotropin and its relation to grade, stage and patient survival in ovarian cancer

BACKGROUND

An influence of gonadotropins (hCG) on the development of ovarian cancer has been discussed. Therefore, we quantified serum hCG levels in patients with benign and malignant ovarian tumors and the hCG expression in ovarian cancer tissue in order to analyze its relation to grade, stage, gonadotropin receptor (LH-R, FSH-R) expression and survival in ovarian cancer patients.

METHODS

Patients diagnosed and treated for ovarian tumors from 1990 to 2002 were included. Patient characteristics, histology including histological subtype, tumor stage, grading and follow-up data were available. Serum hCG concentration measurement was performed with ELISA technology, hCG tissue expression determined by immunohistochemistry.

RESULTS

HCG-positive sera were found in 26.7% of patients with benign and 67% of patients with malignant ovarian tumors. In addition, significantly higher hCG serum concentrations were observed in patients with malignant compared to benign ovarian tumors (p = 0.000). Ovarian cancer tissue was positive for hCG expression in 68%. We identified significant differences in hCG tissue expression related to tumor grade (p = 0.022) but no differences with regard to the histological subtype. In addition, mucinous ovarian carcinomas showed a significantly increased hCG expression at FIGO stage III compared to stage I (p = 0.018). We also found a positive correlation of hCG expression to LH-R expression, but not to FSH-R expression. There was no significant correlation between tissue hCG expression and overall ovarian cancer patient survival, but subgroup analysis revealed an increased 5-year survival in LH-R positive/FSH-R negative and hCG positive tumors (hCG positive 75.0% vs. hCG negative 50.5%).

CONCLUSIONS

Serum human gonadotropin levels differ in patients with benign and malignant ovarian tumors. HCG is often expressed in ovarian cancer tissue with a certain variable relation to grade and stage. HCG expression correlates with LH-R expression in ovarian cancer tissue, which has previously been shown to be of prognostic value. Both, the hormone and its receptor, may therefore serve as targets for new cancer therapies.

Terminal monosaccharide expression on amniotic glycoproteins as biomarkers of fetus maturity

Glycotypes, particularly those that terminate with sialic acid and fucose are known to play a fundamental role in human development, during implantation, growth and differentiation of fetal tissues. The present review describes changes in the exposition of terminal sialic acid and fucose isoforms in the amniotic fluid glycoconjugates, α1-acid glycoprotein and fibronectin during critical stages of pregnancy, i.e. second and third trimester, perinatal period, delivery and post-date pregnancy. The distinct amniotic glycoforms are suggested to be implicated in regulatory processes to ensure homoeostasis during pregnancy and to protect the fetus. These may have the potential of becoming additional laboratory makers in obstetrics to monitor pregnancy.

Review: hCG, preeclampsia and regulatory T cells

Human chorionic gonadotropin (hCG) is crucial for successful pregnancy. Its many functions include angiogenesis and immune regulation. Despite years of research, the etiology of preeclampsia remains unknown. Marked by insufficient trophoblast invasion and poor spiral artery remodeling, preeclampsia has also been linked to immune dysregulation. Here we discuss the roles of hCG in the context of endovascular cross-talk between trophoblasts and endothelial cells and immune tolerance. We propose that functional and glycosylation modifications of hCG may contribute to the pathogenesis of preeclampsia.

Chronic chorioamnionitis displays distinct alterations of the amniotic fluid proteome

Acute chorioamnionitis of infectious origin and chronic chorioamnionitis of immunological origin are two major placental lesions of spontaneous preterm birth with elevated amniotic fluid interleukin-6 and CXCL10 concentrations, respectively. The changes in the amniotic fluid proteome associated with intra-amniotic infection and acute chorioamnionitis are well defined, yet alterations unique to chronic chorioamnionitis remain to be elucidated. This study was conducted to determine those amniotic fluid proteins changing specifically in the presence of chronic chorioamnionitis. Amniotic fluid obtained from acute chorioamnionitis, chronic chorioamnionitis and gestational age-matched controls were analysed by two-dimensional (2D) difference in gel electrophoresis and MALDI-TOF analyses. The type of histological inflammation was used to define each condition in preterm labour cases (n = 125) and term not in labour cases (n = 22), and the amniotic fluid concentrations of interleukin-6, CXCL8, CXCL10 and prostaglandin F(2α) were also measured by specific immunoassays. Among preterm labour cases, 31 differentially expressed proteins were identified in chronic chorioamnionitis cases as compared to both acute chorioamnionitis and control cases. Importantly, glycodelin-A, which maintains maternal tolerance against an allogeneic fetus, was decreased in chronic chorioamnionitis, while haptoglobin was increased. We report the amniotic fluid proteome of chronic chorioamnionitis for the first time, and the findings herein strongly suggest that there is a pathophysiological association between the changes of immunomodulatory proteins in the amniotic fluid and chronic chorioamnionitis, a histological manifestation of maternal anti-fetal allograft rejection.