Apoptosis of extravillous trophoblast cells limits the trophoblast invasion in uterine but not in tubal pregnancy during first trimester

Epigenetic changes regulating the epithelial-mesenchymal transition in human trophoblast differentiation

The phenotype of human placental extravillous trophoblast (EVT) at the end of pregnancy reflects both first trimester differentiation from villous cytotrophoblast (CTB) and later gestational changes, including loss of proliferative and invasive capacity. Invasion abnormalities are central to two major placental pathologies, preeclampsia and placenta accreta spectrum, so characterization of the corresponding normal processes is crucial. In this report, our gene expression analysis, using purified human CTB and EVT cells, highlights an epithelial-mesenchymal transition (EMT) mechanism underlying CTB-EVT differentiation and provides a trophoblast-specific EMT signature. In parallel, DNA methylation profiling shows that CTB cells, already hypomethylated relative to non-trophoblast cell lineages, show further genome-wide hypomethylation in the transition to EVT. However, a small subgroup of genes undergoes gains of methylation (GOM) in their regulatory regions or gene bodies, associated with differential mRNA expression (DE). Prominent in this GOM-DE group are genes involved in the EMT, including multiple canonical EMT markers and the EMT-linked transcription factor RUNX1, for which we demonstrate a functional role in modulating the migratory and invasive capacities of JEG3 trophoblast cells. This analysis of DE associated with locus-specific GOM, together with functional studies of an important GOM-DE gene, highlights epigenetically regulated genes and pathways acting in human EVT differentiation and invasion, with implications for obstetric disorders in which these processes are dysregulated.

A spatially resolved timeline of the human maternal-fetal interface

Beginning in the first trimester, fetally derived extravillous trophoblasts (EVTs) invade the uterus and remodel its spiral arteries, transforming them into large, dilated blood vessels. Several mechanisms have been proposed to explain how EVTs coordinate with the maternal decidua to promote a tissue microenvironment conducive to spiral artery remodelling (SAR)1-3. However, it remains a matter of debate regarding which immune and stromal cells participate in these interactions and how this evolves with respect to gestational age. Here we used a multiomics approach, combining the strengths of spatial proteomics and transcriptomics, to construct a spatiotemporal atlas of the human maternal-fetal interface in the first half of pregnancy. We used multiplexed ion beam imaging by time-of-flight and a 37-plex antibody panel to analyse around 500,000 cells and 588 arteries within intact decidua from 66 individuals between 6 and 20 weeks of gestation, integrating this dataset with co-registered transcriptomics profiles. Gestational age substantially influenced the frequency of maternal immune and stromal cells, with tolerogenic subsets expressing CD206, CD163, TIM-3, galectin-9 and IDO-1 becoming increasingly enriched and colocalized at later time points. By contrast, SAR progression preferentially correlated with EVT invasion and was transcriptionally defined by 78 gene ontology pathways exhibiting distinct monotonic and biphasic trends. Last, we developed an integrated model of SAR whereby invasion is accompanied by the upregulation of pro-angiogenic, immunoregulatory EVT programmes that promote interactions with the vascular endothelium while avoiding the activation of maternal immune cells.

An imbalance of the IL-33/ST2-AXL-efferocytosis axis induces pregnancy loss through metabolic reprogramming of decidual macrophages

During embryo implantation, apoptosis is inevitable. These apoptotic cells (ACs) are removed by efferocytosis, in which macrophages are filled with a metabolite load nearly equal to the phagocyte itself. A timely question pertains to the relationship between efferocytosis-related metabolism and the immune behavior of decidual macrophages (dMΦs) and its effect on pregnancy outcome. Here, we report positive feedback of IL-33/ST2-AXL-efferocytosis leading to pregnancy failure through metabolic reprogramming of dMΦs. We compared the serum levels of IL-33 and sST2, along with IL-33 and ST2, efferocytosis and metabolism of dMΦs, from patients with normal pregnancies and unexplained recurrent pregnancy loss (RPL). We revealed disruption of the IL-33/ST2 axis, increased apoptotic cells and elevated efferocytosis of dMΦs from patients with RPL. The dMΦs that engulfed many apoptotic cells secreted more sST2 and less TGF-β, which polarized dMΦs toward the M1 phenotype. Moreover, the elevated sST2 biased the efferocytosis-related metabolism of RPL dMΦs toward oxidative phosphorylation and exacerbated the disruption of the IL-33/ST2 signaling pathway. Metabolic disorders also lead to dysfunction of efferocytosis, resulting in more uncleared apoptotic cells and secondary necrosis. We also screened the efferocytotic molecule AXL regulated by IL-33/ST2. This positive feedback axis of IL-33/ST2-AXL-efferocytosis led to pregnancy failure. IL-33 knockout mice demonstrated poor pregnancy outcomes, and exogenous supplementation with mouse IL-33 reduced the embryo losses. These findings highlight a new etiological mechanism whereby dMΦs leverage immunometabolism for homeostasis of the microenvironment at the maternal-fetal interface.

MAAPER: model-based analysis of alternative polyadenylation using 3' end-linked reads

Most eukaryotic genes express alternative polyadenylation (APA) isoforms. A growing number of RNA sequencing methods, especially those used for single-cell transcriptome analysis, generate reads close to the polyadenylation site (PAS), termed nearSite reads, hence inherently containing information about APA isoform abundance. Here, we present a probabilistic model-based method named MAAPER to utilize nearSite reads for APA analysis. MAAPER predicts PASs with high accuracy and sensitivity and examines different types of APA events with robust statistics. We show MAAPER's performance with both bulk and single-cell data and its applicability in unpaired or paired experimental designs.

Network analysis reveals important genes in human placenta

AIM

To determine which genes are important in placenta by network analysis.

METHODS

Placenta expressing genes were screened from RNA-Seq data. Protein-protein interaction data were downloaded from STRING (v11.0) database. Google PageRank (PR) algorithm was used to identify important placental genes from protein interaction network. Six placental disease-related datasets were downloaded from NCBI GEO database, and the differential expression of the 99 genes was identified.

RESULTS

We calculated PR for each placenta expressing gene and defined the top 99 genes with high PR as important genes. GAPDH has the highest PR. The 99 genes had different expression pattern in placental cell types. FN1 is up-regulated in 8 w EVT compared to 8 w CTB and 24 w EVT compared to 8 w EVT. HSPA4 is down-regulated in 8 w EVT compared to 8 w CTB and 24 w EVT compared to 8 w EVT. MIB2, TLR4, and UBB are consistently changed in preeclampsia (PE). UBB and ACTG1 were identified to be down-regulated in fetal growth restriction (FGR). SOD1 is down-regulated in preterm birth placenta.

CONCLUSION

Our findings confirmed that the importance of these genes in placenta-related diseases, and provide new candidates (MIB2, UBB, ACTG1, and SOD1) for placenta-related disease diagnosis and treatment.

Illuminating the "Black Box" of Progesterone-Dependent Embryo Implantation Using Engineered Mice

Synchrony between progesterone-driven endometrial receptivity and the arrival of a euploid blastocyst is essential for embryo implantation, a prerequisite event in the establishment of a successful pregnancy. Advancement of embryo implantation within the uterus also requires stromal fibroblasts of the endometrium to transform into epithelioid decidual cells, a progesterone-dependent cellular transformation process termed decidualization. Although progesterone is indispensable for these cellular processes, the molecular underpinnings are not fully understood. Because human studies are restricted, much of our fundamental understanding of progesterone signaling in endometrial periimplantation biology comes from in vitro and in vivo experimental systems. In this review, we focus on the tremendous progress attained with the use of engineered mouse models together with high throughput genome-scale analysis in disclosing key signals, pathways and networks that are required for normal endometrial responses to progesterone during the periimplantation period. Many molecular mediators and modifiers of the progesterone response are implicated in cross talk signaling between epithelial and stromal cells of the endometrium, an intercellular communication system that is critical for the ordered spatiotemporal control of embryo invasion within the maternal compartment. Accordingly, derailment of these signaling systems is causally linked with infertility, early embryo miscarriage and gestational complications that symptomatically manifest later in pregnancy. Such aberrant progesterone molecular responses also contribute to endometrial pathologies such as endometriosis, endometrial hyperplasia and cancer. Therefore, our review makes the case that further identification and functional analysis of key molecular mediators and modifiers of the endometrial response to progesterone will not only provide much-needed molecular insight into the early endometrial cellular changes that promote pregnancy establishment but lend credible hope for the development of more effective mechanism-based molecular diagnostics and precision therapies in the clinical management of female infertility, subfertility and a subset of gynecological morbidities.

Granzyme B-expressing γδ-T and NK cells as a predictor of clinical pregnancy failure in patients with unexplained repeated implantation failure

The limited cytotoxicity of immune cells facilitates a successful establishment of pregnancy. However, the association between cytotoxic granules and unexplained repeated implantation failure (uRIF) remains unkown. Twenty-one fertile controls and 54 patients with uRIF were included in this study. The pregnancy outcomes were monitored at different gestational periods. The peripheral blood lymphocytes were detected using specific monoclonal antibodies by flow cytometry. The percentage of perforin⁺ (Pfr⁺), granzyme B⁺ (GrB⁺), or granulysin⁺ (Gnly⁺) lymphocytes was not significantly different among fertile controls, uRIF patients with successful pregnancy outcomes, and uRIF patients with pregnancy failure. The percentage of GrB⁺ γδ-T cells in lymphocytes was markedly higher in uRIF patients with implantation failure and clinical pregnancy failure than that in uRIF patients with a corresponding successful pregnancy outcome. A four-tier risk model showed that the risk of suffering clinical pregnancy failure in uRIF patients among high risk tier (83.3 %), normal risk tier (65.0 %) and low risk tier (39.1 %) was elevated by 2-4 fold compared with uRIF patients among lowest risk tier (20.0 %). In addition, the percentage of GrB⁺ NK cells in lymphocytes tended to decrease in uRIF patients with pregnancy failure. The AUC of the combined indicator with GrB⁺ γδ-T cells and GrB⁺ NK cells was increased than that of GrB⁺ γδ-T cells and GrB⁺ NK cells for predicting clinical pregnancy failure. In conclusion, the frequency of GrB-expressing γδ-T and NK cells in peripheral blood could serve as a predictor of clinical pregnancy failure in patients with uRIF.

A mouse model of placenta accreta spectrum

INTRODUCTION

Placenta Accreta Spectrum (PAS) disorder is one of the leading causes of maternal morbidity and mortality due to uncontrollable hemorrhage. The greatest risk factor for development of PAS is prior uterine surgery, frequently cesarean delivery. Despite considerable clinical knowledge, animal models of PAS are lacking. To address this, we used two surgical approaches to create uterine scarring in peripartum and non-pregnant CD-1 mice. Il10^-/- mice, with a pro-inflammatory phenotype were also studied.

METHODS

In peripartum mice, a hysterotomy was performed to simulate a cesarean section. The second approach utilized endometrial curettage in non-pregnant mice. Sham-operated mice served as control. Following recovery, females were mated. On gestation day 16, pregnant females were euthanized, and the uterus was excised. Tissue was fixed, sectioned, and stained with H&E or cytokeratin immunohistochemistry. The cytokeratin-positive area extending beyond the trophoblast giant cells was measured by quantitative image analysis. Disruption of the circular (inner myometrium) smooth muscle was scored semi-quantitatively.

RESULTS

In surgically scarred mice, trophoblast invasion was deeper relative to control mice, regardless of surgical method. The myometrium in experimental mice showed significant disruption compared to sham controls. Results from CD-1 and Il10^-/- mice were similar, with the latter showing more severe pathology.

DISCUSSION

While further refinement of surgical method is required, our data indicate that surgical uterine scarring in mice represents a promising model of PAS.

Insights of efferocytosis in normal and pathological pregnancy

Efferocytosis, which is known as the phagocytic clearance of dying cells by professional as well as non-professional phagocytes, including a great number of intracellular/extracellular factors and signals, is interrelated with the immune system, contributing to local and systemic homeostasis, especially in tissues with high constitutive rates of apoptosis. Accumulating studies have indicated that immune dysregulation is associated with the pathogenesis of the female reproductive system, which causes preeclampsia (PE), recurrent spontaneous abortion (RSA), ruptured ectopic pregnancy, and so on. And some studies have revealed the pleiotropic and essential role of efferocytosis in these obstetrical disorders. More specifically, the occurrence and development of these diseases were in connection with some efferocytosis-related factors and signals, such as C1q, MBL, and IL-33/ST2. In this review, we systematically review the diverse impacts of efferocytosis in immune system and discuss its relevance to normal and pathological pregnancy. These findings may instruct future basic researches as well as clinical applications of efferocytosis-related factors and signals as latent predictors or therapeutic targets on the obstetrical disorders.

Alteration of the immune cell profiles in the pathophysiology of tubal ectopic pregnancy

Tubal ectopic pregnancy (TEP) refers to implantation of conceptus in the fallopian tube. It makes up over 98% of ectopic pregnancy (EP), which is the leading cause of maternal morbidity and mortality in the first trimester of pregnancy. Immune cells at the maternal-fetal interface play important roles in the process of embryo implantation, stroma decidualization, and early placental development. Alterations in the composition, phenotype, and activity of the immune cells in the fallopian tubes contribute toward the onset of TEP. In this review, we compare the leukocytic proportions in decidua of normal pregnancy, and in decidua and fallopian tubes of TEP. The possible functions of these immune cells in the pathophysiology of TEP are also discussed.

An insight into the role of the death receptor CD95 throughout pregnancy: Guardian, facilitator, or foe

The prototype death receptor CD95 (Fas) and its ligand, CD95L (FasL), have been thoroughly studied due to their role in immune homeostasis and elimination of infected and transformed cells. The fact that CD95 is present in female reproductive cells and modulated during embryogenesis and pregnancy has raised interest in its role in immune tolerance to the fetoplacental unit. CD95 has been shown to be critical for proper embryonic formation and survival. Moreover, altered expression of CD95 or its ligand causes autoimmunity and has also been directly involved in recurrent pregnancy losses and pregnancy disorders. The objective of this review is to summarize studies that evaluate the mechanisms involved in the activation of CD95 to provide an updated global view of its effect on the regulation of the maternal immune system. Modulation of the CD95 system components may be the immune basis of several common pregnancy disorders.

The increased level of Tspan5 in villi suggests more proliferation and invasiveness of trophoblasts in tubal pregnancy

OBJECTIVE

This study was to determinate the expression of Tspan5 in tubal ectopic implantation sites and to explore the correlation of the expressive level of Tspan5 at maternal-fetal interface and the occurrence of tubal ectopic pregnancy.

STUDY DESIGN

This is a retrospective study. Trophoblastic and endometrial tissues were collected from tubal ectopic pregnancy(Total of 40), and intrauterine pregnancy(Total of 41), who had voluntary abortion, non-pregnancy women(Total of 12), who recieved an diagnostic uterine curettage before IVF-ET for male infertility. All samples were collected from women aged 23-40 years, from February 2012 to January 2014. Results 1. In human villi Tspan5 was primarily located in cytoplasm and on the surfaces of cytotroblasts(CTs) and extravillous trophoblast(EVCTs). The intensity of Tspan5 in tubal pregnancy was significantly higher than that in normal intrauterine pregnancy, showing significant differences (Mean of IOD:109.39 ± 61.84 Vs. 89.04 ± 36.44;t = 2.33, P = 0.023). 2. In human deciduas of intrauterine pregnancy or endometrium of tubal pregnancy and non-pregnancy Tspan5 expressed in cytoplasm and membrane of glandular epithelial cells. The expressive level of this protein was increased in tubal pregnancy than that in intrauterine pregnancy and non-pregnancy(Mean of IOD:144.18 ± 106.22 Vs. 93.43 ± 67.10, P = 0.037; 144.18 ± 106.22 Vs. 88.56 ± 33.24, P = 0.018).

CONCLUSION

Our study indicated that the trophoblasts in tubal pregnancy showed more proliferative and invasive characteristics. Dysregulation of Tspan5 in decidual microenvironment may relate to the retention of embryo in fallopian tube.

SUPPORT

This study was Supported by Science and Technology Planning Project of Guangdong Province.

The significance and evolution of menstruation

Historically, the evolutionary origins of menstruation have been based on two theories: the ability to eliminate infectious agents carried to the uterus with spermatozoa and the comparative conservation of energy with menstruation compared to its absence. In the menstruating species, more recent theories have identified spontaneous decidualization as the key adaptive mechanism. Spontaneous decidualization is seen as a mechanism to provide the mother with protection from the invasive characteristics of the embryo. Physiologically, menstruation involves complex interactions of inflammation and vascular mechanisms to stabilize the endometrium and allow a regulated loss of endometrial tissues and blood. A variety of human illnesses can be better understood as vulnerabilities associated with these evolutionary developments, including recurrent pregnancy loss, placenta accreta, ectopic pregnancy, endometriosis, adenomyosis, dysmenorrhea, and chronic pelvic pain. While the evolutionary aspects of these diseases indicate why such illnesses can occur, in some instances, they also provide a basis for treatment, prevention and future research direction.

Estradiol Elicits Proapoptotic and Antiproliferative Effects in Human Trophoblast Cells

During the first trimester of pregnancy, appropriate regulation of estradiol (E2) is essential for normal placental development. Previous studies demonstrate that premature elevation in E2 concentrations can lead to abnormal placentation, but have not fully elaborated the mechanism of this effect in the first-trimester trophoblast. Our aim was to determine whether E2 elicits trophoblast cell death or inhibits proliferation. The first-trimester human cytotrophoblast cell line HTR-8/SVneo was cultured in phenol red-free medium containing charcoal-stripped serum and treated with 17beta-E2 at concentrations between 0 and 100 nM. TUNEL and invasion assays indicated that E2 significantly increased cell death and reduced cell invasion at 10 nM, and nuclear Ki67 expression revealed that it decreased cell proliferation at 1 nM. A similar effect on cell death was observed in first-trimester placental explants. The E2 antagonist fulvestrant blocked all effects of E2. Immunohistochemistry showed that protein expression of proapoptotic caspases 3, 8, and 9 increased at E2 concentrations of 25 nM and greater, whereas expression of antiapoptotic BCL2-alpha decreased at E2 concentrations of 10 nM and greater. Additionally, treatments with estrogen receptor (ER) alpha-specific and ERbeta-specific agonists at concentrations between 0 and 1000 nM indicated that only ERalpha mediates E2's effects, although immunohistochemistry and Western immunoblotting showed that HTR-8/SVneo cells and placental explants express both ERalpha and ERbeta. Taken together, these findings reveal the interplay between elevated serum E2 and apoptosis in the first trimester of pregnancy. These factors could be associated with pregnancy complications including infertility and uteroplacental insufficiency.

Role of tumor-associated glycoprotein-72 in the progression of endometrial adenocarcinoma: a proposed study

Endometrial adenocarcinoma is on the basis of the molecular, immunohistological and clinicopathologic features broadly divided into two groups, referred as type I and type II. Type I appears more frequently and in principle patients have a good prognosis; however a significant number of patients develop local recurrences. We hypothesize that TAG-72, expressed on endometrial carcinoma binds and internalizes endocytic pattern recognition receptors on surrounding tissue antigen presenting cells (dendritic cells and macrophages), powers their anti-inflammatory maturation program and make them capable to elicit or modulated tolerogenic immune response mediated by local T and NK effectors. This could support uncontrolled local tumor growth, deeper tumor invasion into surrounding tissues, frequent local recurrences and/or lymph node metastasis. To test this hypothesis, we propose a semi-quantitative immunohistochemical analysis of TAG-72 expression in endometrial adenocarcinoma samples and to correlate the results with clinical and pathological parameters (age, type and histological grade of the tumor, estrogen and progesterone receptor expression, invasion into the myometrium and capillaries, presence of lymph node metastases, FIGO stage, and TNM classification). It would be worthwhile to investigate the local tissue immune response in the tumor environment using tissue samples removed during surgery. These studies could elucidate the underlying immunopathological mechanisms that govern the early recurrence and possibly distant metastases of TAG-72-expressing adenocarcinomas and might help in deciding the type of treatment to be applied in a selected group of cancer patients including application of biological therapy with anti-TAG-72 antibodies, according the principle of personalized oncology treatments.

T CD3+CD8+ lymphocytes are more susceptible for apoptosis in the first trimester of normal human pregnancy

Aims. Normal human pregnancy is a complex process of many immunoregulatory mechanisms which protect fetus from the activation of the maternal immune system. The aim of the study was to investigate the apoptosis of lymphocytes in peripheral blood of normal pregnant patients and healthy nonpregnant women. Methods. Sixty pregnant women and 17 nonpregnant women were included in the study. Lymphocytes were isolated and labeled with anti-CD3, anti-CD4, and anti-CD8 monoclonal antibodies. Apoptosis was detected by CMXRos staining and analyzed using the flow cytometric method. Results. We found significantly higher apoptosis of total lymphocytes in peripheral blood of pregnant patients when compared to healthy nonpregnant women. The percentage of apoptotic T CD3⁺CD8⁺ cells in the first trimester was significantly higher when compared to the third trimester of normal pregnancy. The ratio of T CD3⁺CD4⁺ : T CD3⁺CD8⁺ apoptotic lymphocytes was significantly lower in the first trimester when compared to other trimesters of pregnancy and to both of the phases of the menstrual cycle. Conclusions. The higher apoptosis of T CD3⁺CD8⁺ lymphocytes and the lower ratio of T CD3⁺CD4⁺ : T CD3⁺CD8⁺ apoptotic cells in the first trimester of normal pregnancy may suggest a higher susceptibility of T CD3⁺CD8⁺ cells for apoptosis as a protective mechanism at the early stage of pregnancy.

The term basal plate of the human placenta as a source of functional extravillous trophoblast cells

BACKGROUND

Extravillous trophoblast (EVT) cells are of pivotal importance in human embryo implantation and homeostasis of the maternal fetal interface. Invasion of the endometrium by EVT contributes to placental anchorage, spiral artery remodeling, immunological defense, tolerogenic responses, and several collaborative cross talks involved in establishing and maintaining a successful pregnancy. We report here an improved protocol for the isolation of fully differentiated EVT cells from the basal plate of the human term placenta.

METHODS

The basal plate was carefully dissected from the villous tissue and the amniochorion membrane prior to enzymatic digestion. Term basal EVT cells were isolated using a 30 and 60% Percoll gradient. A panel of markers and characteristics of the isolated cells were used to confirm the specificity and efficiency of the method so that their potential as an investigative tool for placental research could be ascertained.

RESULTS

Isolated cells were immunoreactive for cytokeratin-7 (CK-7), placental growth factor, placental alkaline phosphatase, human leukocyte antigen G1 (HLA-G1), and α1 and α5 integrins, similarly to the EVT markers from first trimester placental villi. Around 95% of the isolated cells labeled positively for CK-7 and 82% for HLA-G1. No significant change in viability was observed during 48 h of EVT culture as indicated by propidium iodide incorporation and trypan blue test exclusion. Genes for metalloproteinases MMP-2 and MMP9 (positive regulators of trophoblast invasiveness) were expressed up to 48 h of culturing, as also the gelatinolytic activity of the isolated cells. Transforming growth factor (TGF)-beta, which inhibits proliferation, migration, and invasiveness of first-trimester EVT cells, also reduced invasion of isolated term EVT cells in transwell assays, whereas epidermal growth factor was a positive modulator.

CONCLUSIONS

Term basal plate may be a viable source of functional EVT cells that is an alternative to villous explant-derived EVT cells and cell lines. Isolated term EVT cells may be particularly useful in investigation of the role of trophoblast cells in pathological gestations, in which the precise regulation and interactive ability of extravillous trophoblast has been impaired.

Fetal-maternal interactions in the synepitheliochorial placenta using the eGFP cloned cattle model

Background

To investigate mechanisms of fetal-maternal cell interactions in the bovine placenta, we developed a model of transgenic enhanced Green Fluorescent Protein (t-eGFP) expressing bovine embryos produced by nuclear transfer (NT) to assess the distribution of fetal-derived products in the bovine placenta. In addition, we searched for male specific DNA in the blood of females carrying in vitro produced male embryos. Our hypothesis is that the bovine placenta is more permeable to fetal-derived products than described elsewhere.

Methodology/Principal Findings

Samples of placentomes, chorion, endometrium, maternal peripheral blood leukocytes and blood plasma were collected during early gestation and processed for nested-PCR for eGFP and testis-specific Y-encoded protein (TSPY), western blotting and immunohistochemistry for eGFP detection, as well as transmission electron microscopy to verify the level of interaction between maternal and fetal cells. TSPY and eGFP DNA were present in the blood of cows carrying male pregnancies at day 60 of pregnancy. Protein and mRNA of eGFP were observed in the trophoblast and uterine tissues. In the placentomes, the protein expression was weak in the syncytial regions, but intense in neighboring cells on both sides of the fetal-maternal interface. Ultrastructurally, our samples from t-eGFP expressing NT pregnancies showed to be normal, such as the presence of interdigitating structures between fetal and maternal cells. In addition, channels-like structures were present in the trophoblast cells.

Conclusions/Significance

Data suggested that there is a delivery of fetal contents to the maternal system on both systemic and local levels that involved nuclear acids and proteins. It not clear the mechanisms involved in the transfer of fetal-derived molecules to the maternal system. This delivery may occur through nonclassical protein secretion; throughout transtrophoblastic-like channels and/or by apoptotic processes previously described. In conclusion, the bovine synepitheliochorial placenta displays an intimate fetal-maternal interaction, similar to other placental types for instance human and mouse.

Transformation of a transposon into a derived prolactin promoter with function during human pregnancy

Transposable elements (TEs) are known to provide DNA for host regulatory functions, but the mechanisms underlying the transformation of TEs into cis-regulatory elements are unclear. In humans two TEs--MER20 and MER39--contribute the enhancer/promoter for decidual prolactin (dPRL), which is dramatically induced during pregnancy. We show that evolution of the strong human dPRL promoter was a multistep process that took millions of years. First, MER39 inserted near MER20 in the primate/rodent ancestor, and then there were two phases of activity enhancement in primates. Through the mapping of causal nucleotide substitutions, we demonstrate that strong promoter activity in apes involves epistasis between transcription factor binding sites (TFBSs) ancestral to MER39 and derived sites. We propose a mode of molecular evolution that describes the process by which MER20/MER39 was transformed into a strong promoter, called "epistatic capture." Epistatic capture is the stabilization of a TFBS that is ancestral but variable in outgroup lineages, and is fixed in the ingroup because of epistatic interactions with derived TFBSs. Finally, we note that evolution of human promoter activity coincides with the emergence of a unique reproductive character in apes, highly invasive placentation. Because prolactin communicates with immune cells during pregnancy, which regulate fetal invasion into maternal tissues, we speculate that ape dPRL promoter activity evolved in response to increased invasiveness of ape fetal tissue.

The evolution of menstruation: a new model for genetic assimilation: explaining molecular origins of maternal responses to fetal invasiveness

Why do humans menstruate while most mammals do not? Here, we present our answer to this long-debated question, arguing that (i) menstruation occurs as a mechanistic consequence of hormone-induced differentiation of the endometrium (referred to as spontaneous decidualization, or SD); (ii) SD evolved because of maternal-fetal conflict; and (iii) SD evolved by genetic assimilation of the decidualization reaction, which is induced by the fetus in non-menstruating species. The idea that menstruation occurs as a consequence of SD has been proposed in the past, but here we present a novel hypothesis on how SD evolved. We argue that decidualization became genetically stabilized in menstruating lineages, allowing females to prepare for pregnancy without any signal from the fetus. We present three models for the evolution of SD by genetic assimilation, based on recent advances in our understanding of the mechanisms of endometrial differentiation and implantation. Testing these models will ultimately shed light on the evolutionary significance of menstruation, as well as on the etiology of human reproductive disorders like endometriosis and recurrent pregnancy loss.

Phenotype of NK cells and cytotoxic/apoptotic mediators expression in ectopic pregnancy

PROBLEM

The expression of cytotoxic/apoptotic mediators and the phenotype characteristics of uterine NK cells (uNK) in tubal ectopic pregnancy (EP) were investigated.

METHOD OF STUDY

Samples of uterine decidua and tubal mucosa as well as peripheral blood (PB) of the same women with EP were used for phenotype characterization of NK cells and detection of cytotoxic/apoptotic mediators and IL-15.

RESULTS

In tubal mucosa, perforin, FasL, granulysin and IL-15 were almost completely absent, but they were present in normal and EP uterine deciduas. TRAIL was present on trophoblast and tubal mucosa, contrary to its lack in normal and EP uterine decidua. CD16⁻ CD56(dim) NK cells, mostly CD94⁻ and NKG2A⁻, predominate in tubal mucosa, whereas CD16⁻ CD56(bright) NK cells, predominantly CD94(+) and NKG2A(+) prevail in EP uterine decidua. NK cells at the EP implantation site express lower percentages of perforin and granulysin, but they express a higher percentage of TRAIL than do EP uterine decidual and PB NK cells. Lower percentage of TNF-α-expressing and IL-4-expressing NK cells were found at the implantation site compared to EP uterine decidua.

CONCLUSIONS

Authentic uNK cell population seems to be insufficient to restrict trophoblast invasion because of low expression of cytotoxic/apoptotic mediators.

Uterine natural killer (uNK) cells and their missions during pregnancy: a review

Natural killer (NK) cells are lymphocytes of the innate immune system. The aim of this review is to describe the properties and roles of NK cells in the human uterus during pregnancy. Uterine natural killer cells (uNK) constitute a major lymphocyte population during early gestation in the uterus. The uterine natural killer cells are recognized owing to their CD56(bright), CD16(-), CD3(-) phenotype. Their number increases in the first trimester with a subsequent decline as pregnancy progresses. They have been shown to be closely associated with cells of the extravillous trophoblast (EVT) and spiral arteries. They play important roles in remodeling of the spiral arteries, control of trophoblast invasion and in the development of the placenta. Some studies have shown the number and repertoire of receptors of uNK differ between women with healthy pregnancies and those with pathologic pregnancies, such as pre-eclampsia or intrauterine growth retardation. During pregnancy, the cytotoxic characteristics of the uterine killer cells are not directed towards the fetus, and scientists continue to question and explore this phenomenon with increasing evidence that these cells may perform differing beneficial roles during pregnancy. Contrary to their previously suspected "hostile" characteristics, the uterine killer cells are considered to be "friendly" and appear to be essential and very important regulators of successful implantation and pregnancy.

Tumor-associated glycoprotein (TAG-72) is a natural ligand for the C-type lectin-like domain that induces anti-inflammatory orientation of early pregnancy decidual CD1a+ dendritic cells

Tumor-associated glycoprotein-72 (TAG-72) is physiologically present in secretory phase endometrium, but its presence and possible immunological role in early normal human pregnancy decidua has not received attention. The double labeling of paraffin-embedded early pregnancy decidua sections using B-72.4 anti-TAG-72 mAb and MNF 116 anti-cytokeratin mAb revealed the absence of TAG-72 in uterine decidua of normal and pathological pregnancies (non-embryonic pregnancy and missed abortion) at the implantation sites, although it was present in epithelial cells at and away from the tubal implantation site of an ectopic pregnancy. TAG-72 binds and internalizes by reacting with the mannose receptor (MR-CD206) or with DC-specific ICAM reacting non-integrin (DC-SIGN-CD209) on decidual CD1a+ cells. Decidual CD1a+ cells stimulated with TAG-72 decreased CD83 expression and diminished IL-15 and IFN-γ intracellular production. TAG-72-treated CD1a+ cells decreased IFN-γ production in syngenic decidual and allogenic cord blood T cells even in the presence of lipopolysaccharide. TAG-72- and lipopolysaccharide-pre-treated CD1a+ cells significantly increased IL-4 expression in allogenic cord blood T cells. TAG-72 increased allogenic cord blood T cell proliferation, mediated by decidual CD1a+ cells, compared with its effect on the proliferation of syngenic decidual T cells. All these data emphasize the anti-inflammatory properties of TAG-72-treated decidual CD1a+ cells in terms of their interaction with T cells. Thus, the absence of TAG-72 at the maternal-fetal interface during early pregnancy could lead to a mild pro-inflammatory response that may be beneficial for pregnancy success and trophoblast growth control.

Effect of tumour necrosis factor-α in combination with interferon-γ on first trimester extravillous trophoblast invasion

Successful pregnancy is dependent upon invasion of the uterine tissues by extravillous trophoblast cells (EVT). The mechanisms that control trophoblast invasion are unclear, but several cytokines and growth factors appear to be involved. We have previously demonstrated that IFN-γ inhibits EVT invasion via a mechanism partially dependent on an increase in EVT apoptosis and decreased secretion of matrix metalloproteinase (MMP)-2. In the current study we show that TNF-α, both alone and in combination with IFN-γ, inhibits EVT invasion via a mechanism associated with increased trophoblast apoptosis, decreased trophoblast proliferation and/or altered production of active proteases. TNF-α and its receptors, TNF-αRI and TNF-αRII, were immunolocalised in the placental bed. Uterine natural killer (uNK) cells, EVT and villous cytotrophoblast were shown to all produce TNF-α, and TNF-α receptors were primarily immunolocalised to EVT in the placental bed. TNF-α increased EVT apoptosis, decreased villous cytotrophoblast proliferation and increased expression of pro-MMP-9 (but not active MMP-9), urokinase plasminogen activator (uPA) and plasminogen activator inhibitor (PAI)-1 by EVT. The combination of TNF-α and IFN-γ inhibited EVT via a mechanism associated with increased EVT apoptosis, reduced proliferation, reduced pro-MMP-2 secretion and increased secretion of uPA. TNF-α is one of several decidua-derived factors with the capacity to inhibit EVT invasion. The mode of activity of TNF-α was modified by the presence of IFN-γ, suggesting that the local cytokine milieu may be critical in determining spatial and/or temporal changes in EVT invasion.

The importance of imprinting in the human placenta

As a field of study, genomic imprinting has grown rapidly in the last 20 years, with a growing figure of around 100 imprinted genes known in the mouse and approximately 50 in the human. The imprinted expression of genes may be transient and highly tissue-specific, and there are potentially hundreds of other, as yet undiscovered, imprinted transcripts. The placenta is notable amongst mammalian organs for its high and prolific expression of imprinted genes. This review discusses the development of the human placenta and focuses on the function of imprinting in this organ. Imprinting is potentially a mechanism to balance parental resource allocation and it plays an important role in growth. The placenta, as the interface between mother and fetus, is central to prenatal growth control. The expression of genes subject to parental allelic expression bias has, over the years, been shown to be essential for the normal development and physiology of the placenta. In this review we also discuss the significance of genes that lack conservation of imprinting between mice and humans, genes whose imprinted expression is often placental-specific. Finally, we illustrate the importance of imprinting in the postnatal human in terms of several human imprinting disorders, with consideration of the brain as a key organ for imprinted gene expression after birth.

Placental release of distinct DNA-associated micro-particles into maternal circulation: reflective of gestation time and preeclampsia

BACKGROUND

The aim of this study was to determine whether DNA-associated micro-particles (MPs) in maternal plasma express fetal-derived human leukocyte antigen-G (HLA-G) or placental alkaline phosphatase (PLAP) and whether the levels differ between women with normotensive pregnancies and preeclampsia.

METHODS

DNA-associated MPs expressing HLA-G or PLAP were examined in the plasma of normal pregnant women and preeclamptic patients using flow cytometric analysis.

RESULTS

DNA-associated HLA-G(+) MPs were significantly increased in maternal plasma compared to plasma from non-pregnant controls (p<0.005), with highest levels found in the first and second trimesters. DNA-associated PLAP(+) MPs were also increased in maternal plasma compared to plasma from non-pregnant controls (p<0.006), with highest levels in the second and third trimesters. Term preeclamptic women had higher levels of DNA-associated MPs than control pregnant women. HLA-G(+) MPs from the plasma of preeclamptic women had more DNA per MP than HLA-G(+) MPs from the plasma of normal pregnant women (p<0.03).

CONCLUSIONS

HLA-G(+) and PLAP(+) MPs increase in maternal circulation at different times during gestation. DNA amounts per HLA-G(+) MP increase in preeclamptic women which might indicate dysfunctional extravillous cytotrophoblasts.

Trophoblast invasion

Trophoblast invasion can be seen as a tightly regulated battle between the competing interests of the survival of the fetus and those of the mother. Successful pregnancy is dependent on the trophoblast invading the mother, attaching the pregnancy to the uterus and securing an adequate supply of oxygen and nutrient to the fetus. For successful invasion to occur, extravillous trophoblast has to perform a range of functions; transformation of the maternal spiral arteries, tolerate hypoxia, proliferate and die by apoptosis (programmed cell death), differentiate, adhere to and digest the extracellular matrix, move and interact with the maternal immune system. Each of these functions has multiple overlapping control systems so that trophoblast invasion is a finely controlled balance of competing mechanisms.

Effect of cesarean delivery on the endometrium

OBJECTIVE

To compare endometrial tissue samples from cesarean scar (CS) sites and from the posterior uterine wall to better understand the pathophysiology of implantation into a CS.

METHODS

Endometrial samples were taken from both a CS site and the posterior wall in premenopausal women with CSs, and from the posterior wall in premenopausal women who had spontaneous vaginal deliveries (SVDs) only.

RESULTS

In the secretory phase, there were significantly fewer leukocytes at CS sites than in the endometrium of women who had SVDs only (P<0.05). Significant differences in leukocytic infiltration and cell proliferation between the proliferative and secretory phases were only found in women who had SVDs only (P<0.05).

CONCLUSION

Leukocyte recruitment to the endometrium during the secretory phase may be affected by the presence of a CS.

Epithelial human chorionic gonadotropin is expressed and produced in human secretory endometrium during the normal menstrual cycle

The objective of this study was to determine whether beta human chorionic gonadotropin (hCG) (CGB) subunits and alpha hCG (CGA) subunits are expressed and the hCG dimer is produced in normal human cyclic endometrium. Endometrial specimens were collected for histological dating from women undergoing treatment in our division of human reproduction. RNA from normal secretory endometrium was extracted, and CGB and CGA gene expression was assessed by semiquantitative PCR. Adequate secretory endometrial specimens were homogenized using protease inhibitors. Proteins present in the supernatant were separated electrophoretically, and molecular hCG isoforms were detected by Western blot. The supernatant hCG concentrations were measured by ELISA. We characterized hCG and leukocytes in endometrial specimens by immunohistochemistry. Uterine flushing was performed to confirm endometrial hCG secretion into the uterine fluid. A full-length CGB mRNA encompassing the exon 1 promoter region and the structure exons 2 and 3 (including the C-terminal peptide) was expressed in normal secretory endometrial specimens (similar to CGA) during the early secretory phase of the menstrual cycle, up to an optimum at the midsecretory to late secretory phases. In homogenate supernatants obtained from normal secretory endometrium, hormone concentrations of dimeric hCG were approximately 5 mU per 10 mg of tissue, compared with considerably smaller concentrations of corresponding single free CGB subunit. Single chains of CGB, CGA, and dimeric molecular hCG isoforms were found in endometrial specimens by Western blot. Glandular endometrial hCG production is demonstrated immunohistochemically, with an increase toward the late secretory phase vs. the early secretory phase of the normal secretory menstrual cycle. However, glandular hCG release is diminished or absent in the dyssynchronous or missing endometrial secretory transformation. Endogenous endometrial hCG may be important for implantation and maintenance of pregnancy.

Comparison of macrophage phenotype between decidua basalis and decidua parietalis by flow cytometry

The two regions of the maternal decidua, decidua basalis and decidua parietalis, differ in the extent of trophoblast invasion and consequently in cytokines and other biological mediators, extracellular matrix and cellular components. Our aim was to compare the phenotypic features of macrophages from the two decidual regions across a broad gestational age range. We isolated macrophages by enzymatic digestion from healthy decidua samples obtained after elective abortions, at 9-18-week and at 19-23-weeks, or after term deliveries (caesarean sections at term and spontaneous term vaginal deliveries). Macrophages were analysed by flow cytometry applying the same instrument settings to all the samples to allow semi-quantitative comparison of the expression of a particular marker between different samples. We found higher expressions of CD80, CD86 and HLA-DR, suggestive of a more activated phenotype of decidual macrophages, at early/mid pregnancy than at term. Marginal differences were found between term decidual macrophages obtained after spontaneous vaginal deliveries or caesarean sections which imply that the parturient process is not associated with decidual macrophage activation. The expressions of CD105, DC-SIGN and MMR were the strongest in decidua basalis of mid pregnancy and indicate the importance of decidual macrophages in tissue homeostasis at the uteroplacental interface.

Regulation of natural-killer cell cytotoxicity and enhancement of complement factors in the spontaneously aborted mouse placenta

OBJECTIVE

To evaluate the cytotoxicity of uterine natural killer (NK) cells and identify major biological factors fluctuating in the spontaneously aborted placenta.

DESIGN

Spontaneously aborted placentae were examined by using histology, molecular biology, and DNA microarray analysis.

SETTING

Laboratories and animal center at a medical college.

ANIMAL(S)

C57BL/6 mice.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Up-regulation of the inhibitory system of uterine NK cells and enhancement of complement factors in aborted placenta.

RESULT(S)

In uteri on day 14 of pregnancy, 9.69% +/- 11.6% (+/-SD) implantation sites spontaneously aborted. Labyrinthine trophoblasts at abortion sites had nuclei that were positive for DNA fragment detection, as well as apoptotic morphology. Many uterine NK cells were present at abortion sites, but cytotoxic factors such as perforin, granzyme B, and Fas-Fas ligand were expressed at very low levels. In contrast, the expression level of Ly49 NK-cell receptors, which mediate an inhibitory signal for cytotoxicity, was enhanced at abortion sites. Deoxyribonucleic acid microarray analysis showed that adipsin, an activating enzyme for complement component C3, was strongly enhanced in aborted placenta, and positive reactions for adipsin and C3 were confirmed by immunohistochemistry.

CONCLUSION(S)

In the process of spontaneous abortion, the cytotoxicity of uterine NK cells is inhibited, and the innate immune system through adipsin and complement C3 appears to be influential.

Analysis of metallothionein, RCAS1 immunoreactivity regarding immune cell concentration in the endometrium and tubal mucosa in ectopic pregnancy during the course of tubal rupture

INTRODUCTION

Tubal rupture seems to be linked to a disturbance in maternal immune response and trophoblast cell invasion. The immunomodulating activity of endometrial cells is necessary for the coexistence of activated immune cells and endometrial cells. RCAS1 and metallothionein (MT) participate in this process.

MATERIAL AND METHODS

Tissue samples derived from fallopian tubes and endometrium were collected during one surgical procedure and divided into three groups: unruptured ectopic pregnancy (EP) without bleeding, unruptured EP with hemorrhage into the peritoneal cavity, and ruptured tubal pregnancy. Immunoreactivity of MT, RCAS1, CD56, CD3, CD69 and CD25 were assessed by immunohistochemical methods.

RESULTS

The number of CD3+ and CD56+ cells as well as CD69 antigen immunoreactivity in ruptured tubal mucosa of EP were statistically significantly higher than those measured for unruptured EP without bleeding, while at the same time the number of CD56+ cells in endometrium was statistically significantly lower. The growth of immune cell numbers in tubal mucosa during tubal rupture was not associated with an adequate MT and RCAS1 level.

CONCLUSION

Tubal perforation seems to be linked to a concentration of immune cells and a growth of their activity without an adequate increase of the level of proteins compensating for immune cell response.

RCAS1 decidual immunoreactivity during placental abruption: immune cell presence and activity

PROBLEM

RCAS1 is a protein responsible for the suppression of cytotoxic immune response during gestation. The present study evaluates the immunoreactivity level of RCAS1 with respect to immune cell status during placental abruption (PA) and retained placental tissue (RPT).

METHOD OF STUDY

RCAS1, CD3, CD56, CD69 and CD25 immunoreactivity was assessed by immunohistochemistry in 66 decidual samples derived from PA and from RPT.

RESULTS

RCAS1 immunoreactivity was statistically significantly higher in decidual tissue samples derived from patients with RPT than in those derived from patients with PA. A statistically significantly lower number of CD56(+) and CD3(+) cells and immunoreactivity level of CD69 were found in patients with RPT, compared to those with PA.

CONCLUSION

Placental abruption seems to be associated with excessive accumulation and activity of CD3(+) and CD56(+) cells in decidua, which processes might, in turn, result from an insufficient RCAS1 decidual level.

Indoleamine-dioxygenase is expressed in human decidua at the time maternal tolerance is established

The semi-allogeneic fetus has to be tolerated by the maternal immune system. In mice, it has been shown that inhibiting indoleamine-dioxygenase (IDO) leads to fetal rejection, suggesting a central significance for IDO in establishing maternal tolerance. Consequently, we have analyzed IDO expression in human endometrium and decidua to determine whether it may be of significance in human reproduction. Endometrial (n=60) and decidual (n=68; first and second trimester) tissue samples and isolated cells were analyzed for IDO mRNA and protein expression by real-time PCR, Western blot and immunohistochemistry. IDO expression in the decidua of proven fertile women (n=34) was compared to women presenting with their first pregnancy (n=22) and women with a history of miscarriages (n=12). Expression of IDO was localized in glandular epithelial cells and scattered stromal leukocytes. Expression started at the mid-luteal phase in the menstrual cycle and was high until the second trimester of pregnancy. However, glandular expression of IDO decreased during the second trimester, whereas expression in villous trophoblast started at this time. There were no significant differences in decidual IDO expression between proven fertile women and women presenting with their first pregnancy or women with a history of miscarriages. From the expression pattern we conclude that IDO may play a central role in human pregnancies for the establishment of maternal tolerance of fetal antigens. Thereby, IDO expression may be needed in each pregnancy independently from prior pregnancies, and a history of miscarriage may not reflect a general deficiency in IDO expression.

Comparison of the effect of single-dose and multiple-dose methotrexate therapy on tubal patency

OBJECTIVE

To compare tubal patency by using hysterosalpingography (HSG) in women with unruptured ectopic tubal pregnancy who were treated with either single-dose or multiple-dose methotrexate (MTX) regimen.

DESIGN

A case series with a retrospective statistical analysis.

SETTING

Maternity and teaching hospital in Turkey.

PATIENT(S)

Sixty-one patients treated with MTX therapy for unruptured tubal ectopic pregnancy.

INTERVENTION(S)

Thirty-one patients received single-dose and 30 multiple-dose MTX treatment. The HSG was performed 4 to 6 months after treatment to assess tubal patency.

MAIN OUTCOME MEASURE(S)

Ipsilateral and contralateral tubal obstruction rates.

RESULT(S)

Free passage through the ipsilateral tube was observed in 17 of 30 cases (56.7%) after multiple-dose, and 26 of 31 cases (83.9%) after single-dose MTX therapy. Patency of the contralateral tube was higher after single-dose than multiple-dose MTX treatment, although the value was not statistically significant. Binary logistic regression analysis was used to evaluate the parameters of age, gravida, parity, initial titers of beta human chorionic gonadotropin, size of the adnexal mass, and MTX regimen and their correlation with the HSG results after the clinical treatment for unruptured ectopic pregnancy. Only the type of MTX regimen was found to be used as a predictor of ipsilateral tubal obstruction.

CONCLUSION(S)

In terms of ipsilateral tubal obstruction, multiple-dose MTX therapy appears to have a greater negative effect on tubal patency than single-dose therapy.

Tubal abortions but not viable tubal pregnancies are characterized by an increased number of CD8 + T cells

OBJECTIVE

To examine immune cell phenotypes in viable tubal pregnancies (VTP) and in tubal abortions (TA).

METHODS

Paraffin-embedded specimens of VTP (n=7) and ongoing TA (n=6) were double-stained for cytokeratin for trophoblast as well as for CD45, CD3, CD8, CD68 and CD20 for immune cell phenotypes. In all cases, the amniotic sac was detected by ultrasound. Histological examination showed no evidence of necrosis within the tissues included in this study. Quantification of the subpopulations was performed in each slide by two independent examiners in five areas (0.085 mm2 each) of the invasion zone as marked by cytokeratin-positive stromal extravillous trophoblast (EVT) cells. For statistical analysis, the non-parametric two-tailed t-test was used (p<0.05).

RESULTS

The differences in the number of CD45(+), CD68(+) and CD20(+) cells was significant (p=0.0423, p=0.0469 and p=0.0494, respectively); however, the number of CD3(+), and among those the number of CD8(+) cells, was approximately eight-fold higher in TA than in VTP (p<0.0001 and p=0.0012, respectively).

CONCLUSION

The unequal distribution of CD8(+) cells in VTP and TA suggests a significant role of this immune cell phenotype in the further outcome of a tubal pregnancy either to an abortive or a viable, potentially life-threatening, entity.

Altered protease expression by periarterial trophoblast cells in severe early-onset preeclampsia with IUGR

Adaptation of uteroplacental arteries in patients with early-onset preeclampsia combined with IUGR is compromised due to insufficient invasion of extravillous trophoblast cells (EVT) into the spiral artery wall. The underlying molecular mechanisms are widely unknown. We investigated expression and possible mechanisms of regulation of different matrix-metalloproteases (MMPs) by EVT in placental bed biopsies from patients with early onset preeclampsia combined with IUGR and healthy pregnant women. Expression of MMP-3 and MMP-7 by EVT was markedly reduced in preeclamptic patients, especially close to spiral arteries. In contrast to healthy pregnancies these cells strongly expressed the receptor for leukemia inhibitory factor (LIF). LIF is known to suppress MMP-expression and is produced by uterine natural killer (uNK) cells which we found to be present in higher concentrations in the placental bed of preeclamptic patients, and accumulating aside the spiral arteries. We speculate that in preeclampsia a maternal immune cell network accumulating and interfering in the placental bed leads to an altered cytokine environment, resulting in disturbed trophoblast cell function such as impaired MMP expression and reduced invasiveness.

Apoptosis and its role in the trophoblast

During early placentation the trophoblast of the human placenta differentiates to the villous and extravillous types of trophoblast. Villous trophoblast provides the epithelial cover of the placental villous trees in direct contact to maternal blood. Extravillous trophoblast invades maternal uterine tissues thus directly contacting maternal stromal and immune cells. A subset of extravillous trophoblast, endovascular trophoblast initially occludes the lumen of spiral arteries and comes into direct contact with maternal blood. In recent years apoptosis has been described in both types of trophoblast and the importance of this cascade for the normal function of the trophoblast has become obvious. One feature of serious conditions such as preeclampsia or intrauterine growth restriction is changes in apoptosis regulation in villous and/or extravillous trophoblast resulting in altered trophoblast invasion and/or shedding into the maternal circulation. This review summarizes recent findings on trophoblast apoptosis in normal and pathologic pregnancies.

Metallothionein expression and infiltration of cytotoxic lymphocytes in uterine and tubal implantation sites

INTRODUCTION

In spite of increasing number of immune cells in the endometrium during the decidualization, the integrity of endometrial tissue in each menstrual cycle is maintained by adaptive changes in expression of several factors that regulate activity of immune cells and concomitant hormonal alterations during the menstrual cycle. This regulatory function of endometrium is also related to resistance to apoptosis, in which metallothionein (MT) may play a role.

MATERIALS AND METHODS

Study group included 26 women with spontaneous abortion and 18 patients with tubal ectopic pregnancy. Control group included 17 women whose endometrial tissue samples were taken during the normal secretory cycle phase. Expression of metallothionein (MT), CD56 and CD69 were assessed in tissue samples by immunohistochemistry.

RESULTS

The number of CD56-positive cells was significantly higher in women with ruptured than unruptured ectopics. MT expression was higher in tubal mucosa distant from the implantation site in ruptured compared to unruptured ectopics. It was found also to be significantly lower than in decidua taken from women with spontaneous abortion. CD69 expression was similar in women with spontaneous abortion as well as patients with ruptured ectopics compared to the control group. On the other hand, CD69 expression in unruptured ectopics was significantly lower than in women with spontaneous abortion and the control group.

CONCLUSION

The concentration of immune cells and increase of their activity in tubal mucosa, with insufficient protection against immune-mediated apoptosis assessed by MT expression, might result in tubal rupture during ectopic pregnancy.

Is cervical dilatation during parturition at term associated with apoptosis?

AIMS

Cellular turnover may be involved in remodeling of the cervix during parturition. Therefore, the number and localization of apoptotic and proliferating cells during cervical dilatation at term were determined.

METHODS

Biopsy specimens from the lower uterine segment of 36 women undergoing cesarean section with a cervical dilatation of < 2 cm (n = 10), 2- < 4 cm (n = 9), 4-6 cm (n = 8), and > 6 cm (n = 9) were examined for nuclear fragmentation by the TUNEL assay, and for cell survival by the apoptosis-blocking bcl-2. Proliferation was marked by Ki-67, epithelial cells by cytokeratin and leukocytes by CD 45. For quantification of apoptotic and proliferating cells, eight random fields of each specimen stained for TUNEL or Ki-67 were blindly counted by two investigators. For statistical evaluation, 90% confidence intervals based on a Poisson distribution were used; groups with non-overlapping intervals were considered significantly different.

RESULTS

Apoptotic cells were found exclusively within the stromal compartment, while bcl-2 was expressed in epithelial cells and leukocytes. Proliferating cells were of stromal and epithelial origin. The number of apoptotic as well as proliferating cells ranged from 0 to 2 cells per high-power field (median number 0) in all groups. The confidence intervals were overlapping for all groups, showing no statistical difference between them.

CONCLUSION

Apoptosis does not seem to play a decisive role in the process of cervical dilatation during parturition at term.

Interleukin-11 expression: its significance in eutopic and ectopic human implantation

Embryo implantation and subsequent decidualization, trophoblast invasion and formation of a functional placenta are crucial for establishment and maintenance of pregnancy. Interleukin-11 signalling has been shown to be obligatory for adequate decidualization and trophoblast invasion in mice. Defects in IL-11 signalling in mice result in trophoblast over-invasion and fetal loss. The pathological situation of human tubal pregnancy resembles that of IL-11Ralpha(-/-) mice concerning these symptoms. As our interest is focused on the human early pregnancy, we compared IL-11 expression at the implantation site of ectopic tubal pregnancy (EP) to 1st and 2nd trimester of normal intrauterine pregnancies (IP), and to the normal cycling endometrium. The mRNA expression of IL-11 and IL-11Ralpha was analysed by semiquantitative RT-PCR. Protein expression was detected by western blotting and immunohistochemistry. IL-11Ralpha is expressed constitutively in all tissue specimens analysed. IL-11 is expressed predominantly during follicular and early luteal phase of the menstrual cycle. In IP, IL-11 expression peaks during the 1st trimester and declines from the beginning of the 2nd trimester onwards. In tubal abortions, IL-11 expression is reduced in comparison to vital EP and IP. Cultured primary endometrial and decidual epithelial cells were analysed for hormonal regulation of IL-11 by enzyme-linked immunosorbent assay and RT-PCR. IL-11 is up-regulated by estrogen and down-regulated by progesterone. Overall, our results indicate that in humans, IL-11 signalling is significantly involved in regulation of trophoblast invasion. In the case of tubal abortion, inadequate IL-11 signalling may therefore result in dysregulation of trophoblast invasion.

Atosiban treatment for uterine hyperactivity during active labor: a pilot study

OBJECTIVE

A preliminary assessment of the ability of Atosiban to alleviate uterine hyperactivity during active labor.

METHODS

Fifteen consecutive women with uterine hyperactivity during active labor were included in this prospective observational study. Atosiban was given as a single or repeated intravenous bolus dose (6.75 mg in 0.9 mL NaCl solution) if hyperactivity was not alleviated within 5 minutes with "intrauterine resuscitation" measures.

RESULTS

Alleviation of uterine activity was achieved in 14 out of 15 cases and was almost immediate in the responders. Alleviation of accompanying fetal heart rate abnormalities was achieved in 13 out of 14 cases. In 7 of 15 women a cesarean section was performed, eventually. Atosiban was well tolerated by all women and no side effects were noted. There were no 5 minutes Apgar scores of less than 7. There were no cases of neonatal asphyxia or neonatal mortality.

CONCLUSION

Atosiban may be an effective treatment of uterine hyperactivity during active labor.