Establishment of fetomaternal tolerance through glycan-mediated B cell suppression.

Discrimination of self from non-self is fundamental to a wide range of immunological processes1. During pregnancy, the mother does not recognize the placenta as immunologically foreign because antigens expressed by trophoblasts, the placental cells that interface with the maternal immune system, do not activate maternal T cells2. Currently, these activation defects are thought to reflect suppression by regulatory T cells3. By contrast, mechanisms of B cell tolerance to trophoblast antigens have not been identified. Here we provide evidence that glycan-mediated B cell suppression has a key role in establishing fetomaternal tolerance in mice. B cells specific for a model trophoblast antigen are strongly suppressed through CD22-LYN inhibitory signalling, which in turn implicates the sialylated glycans of the antigen as key suppressive determinants. Moreover, B cells mediate the MHC-class-II-restricted presentation of antigens to CD4+ T cells, which leads to T cell suppression, and trophoblast-derived sialoglycoproteins are released into the maternal circulation during pregnancy in mice and humans. How protein glycosylation promotes non-immunogenic placental self-recognition may have relevance to immune-mediated pregnancy complications and to tumour immune evasion. We also anticipate that our findings will bolster efforts to harness glycan biology to control antigen-specific immune responses in autoimmune disease.

Hospital clinical research activity, rather than staff motivational engagement, significantly links effective staff communication and favourable patient feedback; a cross-sectional study.

OBJECTIVES: Healthcare staff behaviour can impact on the performance of hospitals. Staff involvement in clinical research can have a wider positive effect on patients and hospital performance. The aim of this study was to further assess the putative positive effect of clinical research activity on patient feedback with a more recent dataset, and if staff's motivational engagement levels may impact on aspects of in-patient feedback. METHODS: A retrospective cross-sectional study was conducted with (survey) data from 2019; the sample was 129 English National Health Service hospital Trusts. Sources were the national in-patient survey, national staff survey (for staff motivational engagement), and research activity (based on Trust size-corrected National Institute for Health Research records data). Spearman correlation analyses were conducted (minimum rho value 0.25, p-value<0.005), followed by principal component analysis (score cut-off 0.2). RESULTS: Initial correlation analyses identified eleven in-patient survey questions where better in-patient feedback was associated with increased clinical research activity, and only three questions linked with higher degree of staff motivational engagement. Subsequent principal component analysis confirmed that increased staff engagement is mainly linked to overall Trust performance such as staff levels, whereas staff in research-active hospitals provided in-patients with sufficient information - including on medication - and did well answering patient questions. CONCLUSIONS: Staff involvement in clinical research is associated with better patient feedback. Clear and thorough information provision to patients, may be a mechanism for improved patient outcomes including mortality.

Relationship between staff thriving, through engagement and research activity, and hospital-related outcome measures: A retrospective cross-sectional study.

INTRODUCTION AND OBJECTIVES: Both the standardised hospital mortality index (SHMI) and Care Quality Commission (CQC) ratings are used by the National Health Service (NHS) to monitor performance in English hospitals. We assessed if staff thriving, the concept of vitality and learning at work, through application of the surrogate measures engagement and research activity is associated with more favourable hospital performance outcomes. METHODS: This concerned a retrospective cross-sectional study using data for 129 English NHS hospital Trusts from the year 2019. Outcome measures were SHMI (linear regression, unstandardised coefficient beta) and CQC (binary logistic regression, odds ratio [OR]), whereas the independent variables considered were hospital location, degree of patient deprivation, research activity (drawn from National Institute for Health Research records and controlled for hospital size), and staff engagement scores (based on three survey questions corresponding to validated engagement factors). RESULTS: Staff engagement accounted for over half of the 13% variance R2 for the whole model related to improved CQC rating (OR 13.75, p-value 0.002). Increased research activity was associated with a lower SHMI score (unstandardized beta -0.024, p-value 0.007, R2 5% for each point change in research activity quotient), but independently from the higher SHMI seen for Northern hospital Trusts (beta 0.063, p-value 0.003, R2 11.6%). The degree of patient deprivation did not influence SHMI or CQC outcomes in the regression models. CONCLUSION: Increased staff thriving exhibits a modest, yet significantly, association with improved hospital performance; this was observed despite an underlying regional dichotomy in mortality rates.

The correlation between National Health Service trusts' clinical trial activity and both mortality rates and care quality commission ratings: a retrospective cross-sectional study.

OBJECTIVES: Evidence supporting the notion that clinical research activity in itself is of benefit to organisations as a whole is inconclusive. In the recent past, a positive association between research activity and reduced mortality has been shown. This study aimed to ascertain if clinical research activity is associated with established organisational outcome measures. STUDY DESIGN: Retrospective cross-sectional study. METHODS: For 129 English National Health Service hospital Trusts, National Institute for Health Research study activity data, Summary Hospital-level Mortality Indicator (SHMI) scores and Care Quality Commission (CQC) ratings were collected. Research activity was controlled for Trust size by dividing it by clinical staffing levels. Multiple linear regression and Spearman correlation analyses were performed. RESULTS: Although there is a significant association between the number of studies and participants with both SHMI score and CQC rating, one particular variable is correlated more significantly than others: the number of participants recruited into interventional studies. It shows a significant correlation with better CQC ratings (standardised coefficient beta 0.26, P-value 0.003) and lower SHMI scores (standardised coefficient beta -0.50, P-value 0.001). CONCLUSIONS: The mortality-related results corroborate with other published data showing a correlation between increased research and reduced deaths. Furthermore, there is also a statistically significant association between clinical trials activity and improved CQC ratings. However, these tie-ins are predominantly driven by the number of participants in interventional research rather than observational research activity.

Reductive dissolution of supergrowth carbon nanotubes for tougher nanocomposites by reactive coagulation spinning.

Long single-walled carbon nanotubes, with lengths >10 µm, can be spontaneously dissolved by stirring in a sodium naphthalide N,N-dimethylacetamide solution, yielding solutions of individualised nanotubide ions at concentrations up to 0.74 mg mL-1. This process was directly compared to ultrasonication and found to be less damaging while maintaining greater intrinsic length, with increased individualisation, yield, and concentration. Nanotubide solutions were spun into fibres using a new reactive coagulation process, which covalently grafts a poly(vinyl chloride) matrix to the nanotubes directly at the point of fibre formation. The grafting process insulated the nanotubes electrically, significantly enhancing the dielectric constant to 340% of the bulk polymer. For comparison, samples were prepared using both Supergrowth nanotubes and conventional shorter commercial single-walled carbon nanotubes. The resulting nanocomposites showed similar, high loadings (ca. 20 wt%), but the fibres formed with Supergrowth nanotubes showed significantly greater failure strain (up to ∼25%), and hence more than double the toughness (30.8 MJ m-3), compared to composites containing typical ∼1 µm SWCNTs.

Integrin α4-positive human trophoblast progenitors: functional characterization and transcriptional regulation.

STUDY QUESTION: What are the functional characteristics and transcriptional regulators of human trophoblast progenitor cells (TBPCs)? SUMMARY ANSWER: TBPC lines established from the human smooth chorion by cell sorting for integrin α4 expressed markers of stemness and trophoblast (TB) stage-specific antigens, invaded Matrigel substrates and contributed to the cytotrophoblasts (CTBs) layer of smooth chorion explants with high-mobility group protein HMGI-C (HMGA2) and transcription factor GATA-4 (GATA4) controlling their progenitor state and TB identity. WHAT IS KNOWN ALREADY: Previously, we reported the derivation of TBPC lines by trypsinization of colonies that formed in cultures of chorionic mesenchyme cells that were treated with an activin nodal inhibitor. Microarray analyses showed that, among integrins, α4 was most highly expressed, and identified HMGA2 and GATA4 as potential transcriptional regulators. STUDY DESIGN, SIZE, DURATION: The aim of this study was to streamline TBPC derivation across gestation. High-cell surface expression of integrin α4 enabled the use of a fluorescence-activated cell sorter (FACS) approach for TBPC isolation from the human smooth chorion (n = 6 lines). To confirm their TBPC identity, we profiled their expression of stemness and TB markers, and growth factor receptors. At a functional level, we assayed their invasive capacity (n = 3) and tropism for the CTB layer of the smooth chorion (n = 3). At a molecular level, we studied the roles of HMGA2 and GATA4. PARTICIPANTS/MATERIALS, SETTINGS, METHODS: Cells were enzymatically disassociated from the human smooth chorion across gestation. FACS was used to isolate the integrin α4-positive population. In total, we established six TBPC lines, two per trimester. Their identity was determined by immunolocalization of a suite of antigens. Function was assessed via Matrigel invasion and co-culture with explants of the human smooth chorion. An siRNA approach was used to down-regulate HMGA2 and GATA4 expression and the results were confirmed by immunoblotting and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analyses. The endpoints analyzed included proliferation, as determined by 5-bromo-2'-deoxyuridine (BrDU) incorporation, and the expression of stage-specific antigens and hormones, as determined by qRT-PCR and immunostaining approaches. MAIN RESULTS AND THE ROLE OF CHANCE: As with the original cell lines, the progenitors expressed a combination of human embryonic stem cell and TB markers. Upon differentiation, they primarily formed CTBs, which were capable of Matrigel invasion. Co-culture of the cells with smooth chorion explants enabled their migration through the mesenchyme after which they intercalated within the chorionic CTB layer. Down-regulation of HMGA2 showed that this DNA-binding protein governed their self-renewal. Both HMGA2 and GATA4 had pleitropic effects on the cells' progenitor state and TB identity. LIMITATIONS, REASONS FOR CAUTION: This study supported our hypothesis that TBPCs from the chorionic mesenchyme can contribute to the subpopulation of CTBs that reside in the smooth chorion. In the absence of in vivo data, which is difficult to obtain in humans, the results have the limitations common to all in vitro studies. WIDER IMPLICATIONS OF THE FINDINGS: The accepted view is that progenitors reside among the villous CTB subpopulation. Here, we show that TBPCs also reside in the mesenchymal layer of the smooth chorion throughout gestation. We theorize that they can contribute to the CTB layer in this region. This phenomenon may be particularly important in pathological situations when CTBs of the smooth chorion might provide a functional reserve for CTBs of the placenta proper. STUDY FUNDING/COMPETING INTERESTS: Research reported in this publication was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health under award P50HD055764. O.G., N.L., K.O., A.P., T.G.-G., M.K., A.B., M.G. have nothing to disclose. S.J.F. received licensing fees and royalties from SeraCare Life Sciences for trisomic TBPC lines that were derived according to the methods described in this manuscript. TRIAL REGISTRATION NUMBER: N/A.

A genomics-based framework for identifying biomarkers of human neurodevelopmental toxicity.

Human embryonic stem cell (hESC) neural differentiation models have tremendous potential for evaluating environmental compounds in terms of their ability to induce neurodevelopmental toxicity. Genomic based-approaches are being applied to identify changes underlying normal human development (in vitro and in vivo) and the effects of environmental exposures. Here, we investigated whether mechanisms that are shared between hESC neural differentiation model systems and human embryos are candidate biomarkers of developmental toxicities for neurogenesis. We conducted a meta-analysis of transcriptomic datasets with the goal of identifying differentially expressed genes that were common to the hESC-model and human embryos. The overlapping NeuroDevelopmental Biomarker (NDB) gene set contained 304 genes which were enriched for their roles in neurogenesis. These genes were investigated for their utility as candidate biomarkers in the context of toxicogenomic studies focused on the effects of retinoic acid, valproic acid, or carbamazepine in hESC models of neurodifferentiation. The results revealed genes, including 13 common targets of the 3 compounds, that were candidate biomarkers of neurotoxicity in hESC-based studies of environmental toxicants.

NHS Trusts' clinical research activity and overall CQC performance - Is there a correlation?

OBJECTIVE: Since the late 2000's, the creation of the National Institute for Health Research (NIHR) has transformed clinical research activity in the United Kingdom. This study sought to establish if there is a link between clinical research activity and overall NHS Trust performance. STUDY DESIGN: Retrospective cohort study. METHODS: Data for NHS Trust performance were obtained from public databases, namely the Care Quality Commission (CQC) 2013 risk rating for overall performance, and 2012-13 NIHR records for clinical research activity. RESULTS: Applying Spearman's rank analysis, none of the Trust categories showed a correlation with CQC risk rating: small hospitals, r = -0.062 (P = 0.76; n = 27); medium, r = -0.224 (P = 0.13; n = 47); large, r = -0.008 (P = 0.96; n = 57); academic, r = -0.18 (P = 0.41; n = 24). Similar results were observed when CQC risk rating was compared with the number of different clinical research studies conducted per Trust. CONCLUSION: The degree of NIHR National Portfolio clinical research activity is not significantly related to CQC risk rating, used as an indicator of overall NHS Trust performance. Other studies have previously shown that increased research activity correlates with improved mortality rates, one component of CQC risk rating scores. Alternative tools may have to be explored to evaluate the impact of clinical research on NHS Trusts and its patients.

SynchWeb: a modern interface for ISPyB.

SynchWeb is a modern interface to the ISPyB database. It significantly simplifies sample registration and is targeted towards live data collection monitoring and remote access for macromolecular crystallography. It adds a variety of new features including project management, an integrated diffraction image viewer, and a map and model viewer, as well as displaying results from automated analysis pipelines. Virtually all aspects of an experiment can be monitored through the web browser and the success of each experiment can be evaluated.

Perdeuteration: improved visualization of solvent structure in neutron macromolecular crystallography.

The 1.8 Šresolution neutron structure of deuterated type III antifreeze protein in which the methyl groups of leucine and valine residues are selectively protonated is presented. Comparison between this and the 1.85 Šresolution neutron structure of perdeuterated type III antifreeze protein indicates that perdeuteration improves the visibility of solvent molecules located in close vicinity to hydrophobic residues, as cancellation effects between H atoms of the methyl groups and nearby heavy-water molecules (D2O) are avoided.

Effect of gender on treatment outcomes in type 2 diabetes mellitus.

AIM: To evaluate the effect of gender on clinical outcomes in people with type 2 diabetes mellitus (T2DM) receiving antidiabetes therapy. METHODS: This is a pooled analysis from nine similarly designed phase 3 and 4 randomized, controlled studies evaluating insulin glargine and an active comparator (NPH insulin, insulin lispro, premixed insulin, oral antidiabetes drugs, dietary intervention) in adults with T2DM. Impact of gender on outcomes including HbA1c, fasting plasma glucose (FPG), weight-adjusted insulin dose, and hypoglycemia incidence was evaluated after 24 weeks of treatment. RESULTS: Overall, 1651 male and 1287 female individuals were included; 49.8% and 50.2% were treated with insulin glargine or comparators, respectively. Females receiving insulin glargine were less likely than males to achieve a glycemic target of HbA1c≤7.0% (53mmol/mol) (54.3% vs 60.8%, respectively, p=0.0162); there was no difference between females and males receiving comparators (52.7% vs 51.3%, respectively, p=0.4625). Females had significantly greater reductions in FPG (3.1mg/dL, p=0.0458), required significantly higher insulin doses (0.03IU/kg, p=0.0071), and had significantly higher annual rates of symptomatic (p<0.0001), glucose-confirmed (<50 and <70mg/dL) symptomatic (p=0.0005 and p<0.0001), and severe hypoglycemia (p=0.0020) than males. CONCLUSIONS: Females in this analysis had smaller reductions in HbA1c and were less likely to reach glycemic goals despite higher insulin doses and more hypoglycemic events than males. Differences in gender responses to therapy should be considered when individualizing treatment for people with T2DM.

Protonation-state determination in proteins using high-resolution X-ray crystallography: effects of resolution and completeness.

A bond-distance analysis has been undertaken to determine the protonation states of ionizable amino acids in trypsin, subtilisin and lysozyme. The diffraction resolutions were 1.2 Šfor trypsin (97% complete, 12% H-atom visibility at 2.5σ), 1.26 Šfor subtilisin (100% complete, 11% H-atom visibility at 2.5σ) and 0.65 Šfor lysozyme (PDB entry 2vb1; 98% complete, 30% H-atom visibility at 3σ). These studies provide a wide diffraction resolution range for assessment. The bond-length e.s.d.s obtained are as small as 0.008 Šand thus provide an exceptional opportunity for bond-length analyses. The results indicate that useful information can be obtained from diffraction data at around 1.2-1.3 Šresolution and that minor increases in resolution can have significant effects on reducing the associated bond-length standard deviations. The protonation states in histidine residues were also considered; however, owing to the smaller differences between the protonated and deprotonated forms it is much more difficult to infer the protonation states of these residues. Not even the 0.65 Šresolution lysozyme structure provided the necessary accuracy to determine the protonation states of histidine.

An investigation into the protonation states of the C1 domain of cardiac myosin-binding protein C.

Myosin-binding protein C (MyBP-C) is a myofibril-associated protein found in cardiac and skeletal muscle. The cardiac isoform (cMyBP-C) is subject to reversible phosphorylation and the surface-charge state of the protein is of keen interest with regard to understanding the inter-protein interactions that are implicated in its function. Diffraction data from the C1 domain of cMyBP-C were extended to 1.30 A resolution, where the of the diffraction data crosses 2.0, using intense synchrotron radiation. The protonation-state determinations were not above 2sigma (the best was 1.81sigma) and therefore an extrapolation is given, based on 100% data completeness and the average DPI, that a 3sigma determination could be possible if X-ray data could be measured to 1.02 A resolution. This might be possible via improved crystallization or multiple sample evaluation, e.g. using robotics or a yet more intense/collimated X-ray beam or combinations thereof. An alternative would be neutron protein crystallography at 2 A resolution, where it is estimated that for the unit-cell volume of the cMyBP-C C1 domain crystal a crystal volume of 0.10 mm3 would be needed with fully deuterated protein on LADI III. These efforts would optimally be combined in a joint X-ray and neutron model refinement.

An investigation into structural changes due to deuteration.

Perdeuteration of proteins is becoming more commonplace and the assumption is in general that deuteration does not affect protein structure. In this work, the effect of deuteration on structure is examined by data mining, largely of the Cambridge Structural Database but also of the Inorganic Crystal Structure Database, for deuterated and hydrogenated pairs of small-molecule structures analysed by neutron and X-ray crystallography. Differences between these small-molecule structures have been calculated and the results thus far follow the initial assumption. However, functional changes are known, e.g. D(2)O is toxic to living systems but H(2)O is not, kinetics change, small pH to pD changes occur, proteins stiffen in D(2)O and ferroelectrics alter their properties.

Decidual stromal cell response to paracrine signals from the trophoblast: amplification of immune and angiogenic modulators.

During the invasive phase of implantation, trophoblasts and maternal decidual stromal cells secrete products that regulate trophoblast differentiation and migration into the maternal endometrium. Paracrine interactions between the extravillous trophoblast and the maternal decidua are important for successful embryonic implantation, including establishing the placental vasculature, anchoring the placenta to the uterine wall, and promoting the immunoacceptance of the fetal allograph. To our knowledge, global crosstalk between the trophoblast and the decidua has not been elucidated to date, and the present study used a functional genomics approach to investigate these paracrine interactions. Human endometrial stromal cells were decidualized with progesterone and further treated with conditioned media from human trophoblasts (TCM) or, as a control, with control conditioned media (CCM) from nondecidualized stromal cells for 0, 3, and 12 h. Total RNA was isolated and processed for analysis on whole-genome, high-density oligonucleotide arrays containing 54,600 genes. We found that 1374 genes were significantly upregulated and that 3443 genes were significantly downregulated after 12 h of coincubation of stromal cells with TCM, compared to CCM. Among the most upregulated genes were the chemokines CXCL1 (GRO1) and IL8,CXCR4, and other genes involved in the immune response (CCL8 [SCYA8], pentraxin 3 (PTX3), IL6, and interferon-regulated and -related genes) as well as TNFAIP6 (tumor necrosis factor alpha-induced protein 6) and metalloproteinases (MMP1, MMP10, and MMP14). Among the downregulated genes were growth factors, e.g., IGF1, FGF1, TGFB1, and angiopoietin-1, and genes involved in Wnt signaling (WNT4 and FZD). Real-time RT-PCR and ELISAs, as well as immunohistochemical analysis of human placental bed specimens, confirmed these data for representative genes of both up- and downregulated groups. The data demonstrate a significant induction of proinflammatory cytokines and chemokines, as well as angiogenic/static factors in decidualized endometrial stromal cells in response to trophoblast-secreted products. The data suggest that the trophoblast acts to alter the local immune environment of the decidua to facilitate the process of implantation and ensure an enriched cytokine/chemokine environment while limiting the mitotic activity of the stromal cells during the invasive phase of implantation.

Molecular cytogenetic studies towards the full karyotype analysis of human blastocysts and cytotrophoblasts.

Numerical chromosome aberrations in gametes typically lead to failed fertilization, spontaneous abortion or a chromosomally abnormal fetus. By means of preimplantation genetic diagnosis (PGD), we now can screen human embryos in vitro for aneuploidy before transferring the embryos to the uterus. PGD allows us to select unaffected embryos for transfer and increases the implantation rate in in vitro fertilization programs. Molecular cytogenetic analyses using multi-color fluorescence in situ hybridization (FISH) of blastomeres have become the major tool for preimplantation genetic screening of aneuploidy. However, current FISH technology can test for only a small number of chromosome abnormalities and hitherto failed to increase the pregnancy rates as expected. We are in the process of developing multi-color FISH-based technologies to score all 24 chromosomes in single cells within a three-day time limit, which we believe is vital to the clinical setting. Also, human placental cytotrophoblasts (CTBs) at the fetal-maternal interface acquire aneuploidies as they differentiate to an invasive phenotype. About 20-50% of invasive CTB cells from uncomplicated pregnancies were found to be aneuploid, suggesting that the acquisition of aneuploidy is an important component of normal placentation, perhaps limiting the proliferative and invasive potential of CTBs. Since most invasive CTBs are interphase cells and possess extreme heterogeneity, we applied multi-color FISH and repeated hybridizations to investigate the feasibility of a full karyotype analysis of individual CTBs. In summary, this study demonstrates the strength of Spectral Imaging analysis and repeated hybridizations, which provides a basis for full karyotype analysis of single interphase cells.

Hair cycle and wound healing in mice with a keratinocyte-restricted deletion of FAK.

Focal adhesion kinase (FAK) is a critical component in transducing signals downstream of both integrins and growth factor receptors. To determine how the loss of FAK affects the epidermis in vivo, we have generated a mouse model with a keratinocyte-restricted deletion of fak (FAKK5 KO mice). FAK(K5 KO) mice displayed three major phenotypes--irregularities of hair cycle, sebaceous glands hypoplasia, and a thinner epidermis--pointing to defects in the proliferative capacity of multipotent stem cells found in the bulge. FAK-null keratinocytes in conventional primary culture undergo massive apoptosis hindering further analyses, whereas the defects observed in vivo do not shorten the mouse lifespan. These results suggest that the structure and the signaling environment of the native tissue may overcome the lack of signaling through FAK. Our findings point to the importance of in vivo and three-dimensional in vitro models in analyses of cell migration, proliferation, and survival. Surprisingly, the difference between FAKloxP/+ and FAKK5 KO mice in wound closure was not statistically significant, suggesting that in vivo loss of FAK does not affect migration/proliferation of basal keratinocytes in the same way as it affects multipotent stem cells of the skin.

The adverse effects of maternal smoking on the human placenta: a review.

Studies of placental pathologies associated with maternal cigarette smoking have led to many interesting observations. For example, maternal smoking impairs human placental development by changing the balance between cytotrophoblast (CTB) proliferation and differentiation. It is likely that chronic exposure to tobacco constituents in early pregnancy can affect placental development directly or indirectly by reducing blood flow, which creates a pathologically hypoxic environment. To understand this process at a molecular level, tissue samples from non-smoking and smoking mothers were studied to determine whether active and/or passive cigarette smoke exposure affects CTB expression of molecules that govern cellular responses to oxygen tension: the von Hippel-Lindau tumor suppressor protein (pVHL), hypoxia-inducible transcription factors (HIFs) and vascular endothelial growth factor-A (VEGF). The results show that maternal smoking dysregulates CTB expression of all three types of molecules. In addition, cell columns and proliferating cells were reduced while there was a corresponding increase in cell islands. All three phenomena were most obvious in the placentas of heavy smokers. Interestingly, a subset of the aforementioned effects can be detected in samples obtained from women who were passively exposed to cigarette smoke during pregnancy. These observations suggest that tobacco constituents exert direct effects on CTB proliferation and differentiation and help to explain the mechanisms by which smoking negatively effects human pregnancy outcome.

Trophoblast origin of hCG isoforms: cytotrophoblasts are the primary source of choriocarcinoma-like hCG.

We have previously demonstrated that a hyperglycosylated isoform of chorionic gonadotropin (hCG) (B152 hCG) is detected in the blood and urine in early pregnancy and is subsequently rapidly replaced by the hCG isoform (B109 hCG) characteristic of later pregnancy. In the current study we have extended our work on the origin of these isoforms. We have used a combination of in situ and in vitro approaches. Localization studies in placental tissues showed that monoclonal antibody B109 stained very specifically syncytiotrophoblast (STBs) from first and second trimester tissues. At term, STBs exhibited no B109 staining at all. Immunostaining with B152 antibody, that recognize the hyperglycosylated isoform of hCG, revealed only punctate staining of STBs in most villi of first trimester tissue. Both antibodies B109 and B152 failed to stain cytotrophoblasts (CTBs). To assess the functional relevance of these observations we analyzed conditioned media from purified CTBs using two immunometric assays, one of which (B152-B207*) has primary specificity for the hyperglycosylated, choriocarcinoma-like hCG and the other (B109-B108*) having primary specificity for the later pregnancy hCG isoform. Regardless of gestational age, isolated CTBs secreted predominantly B152 hCG isoform in contrast to placental villi (predominantly STBs), which released primarily the B109 hCG isoform. Isolated CTBs, however, failed to immunostain with both B109 and B152 antibodies. To resolve this contradiction, we cultured CTBs in the presence of brefeldin A, a drug known to block secretion by inhibiting protein translocation from the endoplasmic reticulum to the Golgi vesicles. Brefeldin A treated CTBs stained strongly with B109 and did not stain or stained weakly with B152 antibody. We assume that treatment with brefeldin A impaired glycosylation of beta subunit and consequently inhibited the production of hyperglycosylated form of hCG recognized by B152. In summary, our in vitro experiments indicate that both isoforms of hCG are produced by villus CTBs and that the dominant isoform is the one recognized by antibody B152. STBs produce primarily the less glycosylated B109 hCG isoform. This data suggests that at the beginning of pregnancy villus CTBs are the major source of the B152 hCG isoform. This finding is supported by our clinical data that show that the dominant hCG isoform in the blood and urine of pregnant women in the first 6 weeks of pregnancy is recognized by B152 (). The inversion of the B152/B109 ratio observed after 6-7 weeks of pregnancy can be explained by the reduction of number of villus CTBs and/or by maturation of STBs.