Immunology of human endometrium

Exosomes secreted from adipose-derived stem cells inhibit M1 macrophage polarization ameliorate chronic endometritis by regulating SIRT2/NLRP3

Chronic endometritis (CE) is a key factor in adverse pregnancy outcomes such as miscarriage and infertility. Macrophages are an important immune cell type that secrete pro-inflammatory and anti-inflammatory cytokines that are essential for maintaining endometrial function. This study aimed to investigate the key mechanisms by which exosomes derived from adipose-derived mesenchymal stem cells (ADSCs) regulate macrophage polarization through the sirtuin 2 (SIRT2)/NOD-like receptor pyrin containing 3 (NLRP3) axis and exert a protective effect on CE. Exosomes were obtained from ADSCs (ADSCs-exo) using the classical ultracentrifugation method and characterized using transmission electron microscopy, nanoparticle tracking analysis, and western blotting. ADSCs-exo protective effects on CE mice and RAW 264.7 cells and its related molecular mechanisms were investigated using real-time quantitative polymerase chain reaction, western blotting, enzyme-linked immunosorbent assay, flow cytometry, immunofluorescence, immunoprecipitation, hematoxylin and eosin staining, and immunohistochemistry. ADSCs-exo significantly inhibited M1 macrophage polarization, as evidenced by a 54% reduction in tumor necrosis factor alfa (TNF-α), a 46% reduction in interleukin 1β (IL-1β), and a 36% reduction in interleukin 6 (IL-6) levels in LPS-induced RAW264.7 cells. In vivo, ADSCs-exo treatment reduced the expression of TNF-α by 50%, IL-1β by 58%, and IL-6 by 49% in the uterine tissues of CE mice. Moreover, ADSCs-exo upregulated the expression of SIRT2, promoted the deacetylation modification of NLRP3 to inhibit NLRP3 inflammasome activation, and further suppressed M1 macrophage polarization. However, these trends were reversed after SIRT2 silencing. Our experimental results demonstrate that ADSCs-exo alleviate CE by regulating the SIRT2/NLRP3 axis to inhibit M1 macrophage polarization. This provides a potential theoretical basis for the therapeutic role of stem cells in CE.

Integrated transcriptomic analysis reveals dysregulated immune infiltration and pro-inflammatory cytokines in the secretory endometrium of recurrent implantation failure patients

Recurrent implantation failure (RIF) is a leading impediment to assisted reproductive technology, yet the underlying pathogenesis of RIF remains elusive. Recent studies have sought to uncover novel biomarkers and etiological factors of RIF by profiling transcriptomes of endometrial samples. Nonetheless, the inherent heterogeneity among published studies and a scarcity of experimental validations hinder the identification of robust markers of RIF. Hence, we integrated six publicly accessible datasets with 209 samples, including microarray profiles of endometrial samples in the secretory phase. After removing batch effects, we identified 175 differentially expressed genes. Gene set enrichment analysis identified dysregulation of immunological pathways in RIF. We also observed altered immune infiltration and pro-inflammatory cytokines in RIF. Protein-protein interaction network analysis identified ten hub genes, representing two co-expression modules significantly related to RIF. Knockdown of ENTPD3, one of the hub genes, promoted the epithelial-mesenchymal transition process and resulted in elevated levels of pro-inflammatory cytokines. Collectively, our study reveals abnormal gene expressions involving the regulation of epithelial-mesenchymal transition and immune status in RIF, providing valuable insights into its pathogenesis.

Small secretory proteins of immune cells can modulate gynecological cancers

Small secretory proteins of immune cells are mostly Cytokines, which include chemokines, interleukins, interferons, lymphokines and tumor necrosis factors but not hormones or growth factors. These secretory proteins are the molecular messengers and primarily involved in autocrine, paracrine and endocrine signaling as immunomodulating agents. Hence, these proteins actually regulate the cells of immune system to communicate with one another to produce a synchronized, robust, still self-regulated response to a specific antigen. Chemokines are smaller secreted proteins that control overall immune cell movement and location; these chemokines are divided into 4 subgroups, namely, CXC, CC, CX3C and C according to the position of 4 conserved cysteine residues. Complete characterization of cytokines and chemokines can exploit their vast signaling networks to develop cancer treatments. These secretory proteins like IL-6, IL-10, IL-12, TNFα, CCL2, CXCL4 & CXCL8 are predominantly expressed in most of the gynecological cancers, which directly stimulate immune effector cells and stromal cells at the tumor site and augment tumor cell recognition by cytotoxic T-cells. Hence; these secretory proteins are the major regulators, which can actually modulate all kinds of gynecological cancers. Furthermore, advancements in adoptive T-cell treatment have relied on the use of multiple cytokines/chemokines to establish a highly regulated environment for anti-tumor T cell growth. A number of in vitro studies as well as animal models and clinical subjects have also shown that cytokines/chemokines have broad antitumor activity, which has been translated into a number of cancer therapy approaches. This review will focus on the foremost cytokines & chemokines involved in the majority of the gynecological malignancies and discuss their basic biology as well as clinical applications.

Aging endometrium in young women: molecular classification of endometrial aging-based markers in women younger than 35 years with recurrent implantation failure

BACKGROUND

To explore the differences between a population with premature endometrial aging and a population with normal endometrial status in young women with recurrent implantation failure (< 35 years).

METHODS

Systematic analysis of the endometrium transcriptome of 274 RIF women. The NMF algorithm was used for classification based on endometrial-specific aging markers in CellAge, and the endometrial receptivity, gene expression patterns, and clinical data were compared between the classifications.

RESULTS

Two hundred forty-five young RIF women could be divided into two clusters, in which the aging gene expression pattern of cluster 2 was closer to the reference cluster. Cluster 1 was characterized by high immune activity, while cluster 2 was characterized by high metabolic activity. Combined with clinical data, cluster 2 was worse than cluster 1 in window of implantation deviation rate and endometrial receptivity.

CONCLUSION

Premature aging of the endometrium exists in young women with RIF, and premature aging of the endometrium was associated with poor reproductive outcomes.

Correlation of TNF-α, IFN-γ and TGF-β Expression with In-vitro Fertilization Success Rates in Women with Recurrent Implantation Failure Undergoing Treatment with Intra-lipid Infusion

This study aimed at assessing the correlations between gene expression of TNF-a, IFN-g, TGF-β in peripheral lymphocytes from women suffering from repeated implantation failure before and after intravenous Intra-lipid (IL) therapy, and correlation between changes in gene expression with IL infusion and success rate of IVF cycles. Twenty-three women complaining of unexplained infertility without history of autoimmune disorders, or immunodeficient diseases were included. All women included aged <40 years, BMI <28 with history of recurrent IVF cycles failure, seeking medical advice for new IVF trial. All were average responders to induction of ovulation (≥5 oocytes in each cycle) with good quality embryos transferred to uterus at proper time. Included women received 200 ml of 10% IL slowly intravenous. Two venous blood samples were taken from all candidates, one before IL infusion and the second was at day of embryo transfer. The current study detected a significant reduction of expression in TNF-a and increased expression of TGF-β, while non-significant reduction in expression of IFN-g after treatment. Significant associations between reduction of TNF-α, IFN-g expression and positive clinical and ongoing pregnancy were observed, while increased TGF-β expression was associated with only positive ongoing pregnancy. In conclusion, IL therapy might have a positive impact on IVF pregnancy rates via alterations in peripheral cytokines expression mainly reduction of TNF-a mRNA expression and increased TGF-b mRNA expression.

Constraint-Based, Score-Based and Hybrid Algorithms to Construct Bayesian Gene Networks in the Bovine Transcriptome

Simple Summary

In this study, we investigated and compared six different Bayesian network algorithms from three different categories to identify hub genes critical to gene expression networks activated in response to progesterone in the bovine uterus. We observed many common hub genes identified between constraint-based algorithms (CBAs) and hybrid algorithms (HAs), while it appeared that score-based algorithm (SBA) methods led to more accurate and relevant predictions of core genes. The results revealed that the identification of hub genes was affected by the type of network reconstruction and by the subsequently used topological parameters. Two identified genes known to have roles during pregnancy are ISG15 and DGAT2. The identified hub genes are associated with biological processes such as amino acid metabolism, hormonal signaling pathways and the immune system. Our analysis revealed a role for miRNAs in the regulation of this system. The biological and physiological roles (enzymatic and hormonal effects) of unannotated identified hub genes should be functionally validated by further studies.

Abstract

Bayesian gene networks are powerful for modelling causal relationships and incorporating prior knowledge for making inferences about relationships. We used three algorithms to construct Bayesian gene networks around genes expressed in the bovine uterus and compared the efficacies of the algorithms. Dataset GSE33030 from the Gene Expression Omnibus (GEO) repository was analyzed using different algorithms for hub gene expression due to the effect of progesterone on bovine endometrial tissue following conception. Six different algorithms (grow-shrink, max-min parent children, tabu search, hill-climbing, max-min hill-climbing and restricted maximum) were compared in three higher categories, including constraint-based, score-based and hybrid algorithms. Gene network parameters were estimated using the bnlearn bundle, which is a Bayesian network structure learning toolbox implemented in R. The results obtained indicated the tabu search algorithm identified the highest degree between genes (390), Markov blankets (25.64), neighborhood sizes (8.76) and branching factors (4.38). The results showed that the highest number of shared hub genes (e.g., proline dehydrogenase 1 (PRODH), Sam-pointed domain containing Ets transcription factor (SPDEF), monocyte-to-macrophage differentiation associated 2 (MMD2), semaphorin 3E (SEMA3E), solute carrier family 27 member 6 (SLC27A6) and actin gamma 2 (ACTG2)) was seen between the hybrid and the constraint-based algorithms, and these genes could be recommended as central to the GSE33030 data series. Functional annotation of the hub genes in uterine tissue during progesterone treatment in the pregnancy period showed that the predicted hub genes were involved in extracellular pathways, lipid and protein metabolism, protein structure and post-translational processes. The identified hub genes obtained by the score-based algorithms had a role in 2-arachidonoylglycerol and enzyme modulation. In conclusion, different algorithms and subsequent topological parameters were used to identify hub genes to better illuminate pathways acting in response to progesterone treatment in the bovine uterus, which should help with our understanding of gene regulatory networks in complex trait expression.

Diagnostic and Therapeutic Potential for HNP-1, HBD-1 and HBD-4 in Pregnant Women with COVID-19

Pregnancy is characterized by significant immunological changes and a cytokine profile, as well as vitamin deficiencies that can cause problems for the correct development of a fetus. Defensins are small antimicrobial peptides that are part of the innate immune system and are involved in several biological activities. Following that, this study aims to compare the levels of various cytokines and to investigate the role of defensins between pregnant women with confirmed COVID-19 infection and pregnant women without any defined risk factor. TNF-α, TGF-β, IL-2 and IL-10, β-defensins, have been evaluated by gene expression in our population. At the same time, by ELISA assay IL-6, IL-8, defensin alpha 1, defensin beta 1 and defensin beta 4 have been measured. The data obtained show that mothers affected by COVID-19 have an increase in pro-inflammatory factors (TNF-α, TGF-β, IL-2, IL-6, IL-8) compared to controls; this increase could generate a sort of “protection of the fetus” from virus attacks. Contemporarily, we have an increase in the anti-inflammatory cytokine IL-10 and an increase in AMPs, which highlights how the mother’s body is responding to the viral attack. These results allow us to hypothesize a mechanism of “trafficking” of antimicrobial peptides from the mother to the fetus that would help the fetus to protect itself from the infection in progress.

Interaction Between Chronic Endometritis Caused Endometrial Microbiota Disorder and Endometrial Immune Environment Change in Recurrent Implantation Failure

Objective

To investigate the Interaction between chronic endometritis (CE) caused endometrial microbiota disorder and endometrial immune environment change in recurrent implantation failure (RIF).

Method

Transcriptome sequencing analysis of the endometrial of 112 patients was preform by using High-Throughput Sequencing. The endometrial microbiota of 43 patients was analyzed by using 16s rRNA sequencing technology.

Result

In host endometrium, CD4 T cell and macrophage exhibited significant differences abundance between CE and non-CE patients. The enrichment analysis indicated differentially expressed genes mainly enriched in immune-related functional terms. Phyllobacterium and Sphingomonas were significantly high infiltration in CE patients, and active in pathways related to carbohydrate metabolism and/or fat metabolism. The increased synthesis of lipopolysaccharide, an important immunomodulator, was the result of microbial disorders in the endometrium.

Conclusion

The composition of endometrial microorganisms in CE and non-CE patients were significantly different. Phyllobacterium and Sphingomonas mainly regulated immune cells by interfering with the process of carbohydrate metabolism and/or fat metabolism in the endometrium. CE endometrial microorganisms might regulate Th17 response and the ratio of Th1 to Th17 through lipopolysaccharide (LPS).

Measles and Pregnancy: Immunity and Immunization-What Can Be Learned from Observing Complications during an Epidemic Year

Measles is a highly contagious airborne disease. Unvaccinated pregnant women are not only at risk of infection but also at risk of severe pregnancy complications. As measles causes a dysregulation of the entire immune system, we describe immunological variations and how immune response mechanisms can lead to adverse pregnancy outcomes. We evaluated data during the measles outbreak reported in the province of Catania, Italy, from May 2017 to June 2018. We controlled hospital discharge records for patients admitted to hospital obstetric wards searching the measles diagnostic code. We have indicated the case as "confirmed" when the IgM was found to be positive with the ELISA method. We registered 843 cases of measles and 51% were females (430 cases). 24 patients between the ages of 17 and 40 had measles while they were pregnant. Adverse pregnancy outcomes included 2 spontaneous abortions, 1 therapeutic abortion, 1 foetal death, and 6 preterm deliveries. Respiratory complications were more prevalent in pregnant women (21%) than in nonpregnant women with measles (9%). 14 health care workers (1.7%) were infected with measles, and none of these had been previously vaccinated. Immune response mechanisms were associated with adverse pregnancy outcomes in women with measles. To reduce the rate of measles complications, gynaecologists should investigate vaccination history and antibody test results in all women of childbearing age. During a measles outbreak, gynaecologists and midwives should be active proponents of vaccination administration and counteract any vaccine hesitancy not only in patients but also among health care workers.

How uterine microbiota might be responsible for a receptive, fertile endometrium

BACKGROUND

Fertility depends on a receptive state of the endometrium, influenced by hormonal and anatomical adaptations, as well as the immune system. Local and systemic immunity is greatly influenced by microbiota. Recent discoveries of 16S rRNA in the endometrium and the ability to detect low-biomass microbiota fueled the notion that the uterus may be indeed a non-sterile compartment. To date, the concept of the 'sterile womb' focuses on in utero effects of microbiota on offspring and neonatal immunity. However, little awareness has been raised regarding the importance of uterine microbiota for endometrial physiology in reproductive health; manifested in fertility and placentation.

OBJECTIVE AND RATIONALE

Commensal colonization of the uterus has been widely discussed in the literature. The objective of this review is to outline the possible importance of this uterine colonization for a healthy, fertile uterus. We present the available evidence regarding uterine microbiota, focusing on recent findings based on 16S rRNA, and depict the possible importance of uterine colonization for a receptive endometrium. We highlight a possible role of uterine microbiota for host immunity and tissue adaptation, as well as conferring protection against pathogens. Based on knowledge of the interaction of the mucosal immune cells of the gut with the local microbiome, we want to investigate the potential implications of commensal colonization for uterine health.

SEARCH METHODS

PubMed and Google Scholar were searched for articles in English indexed from 1 January 2008 to 1 March 2018 for '16S rRNA', 'uterus' and related search terms to assess available evidence on uterine microbiome analysis. A manual search of the references within the resulting articles was performed. To investigate possible functional contributions of uterine microbiota to health, studies on microbiota of other body sites were additionally assessed.

OUTCOMES

Challenging the view of a sterile uterus is in its infancy and, to date, no conclusions on a 'core uterine microbiome' can be drawn. Nevertheless, evidence for certain microbiota and/or associated compounds in the uterus accumulates. The presence of microbiota or their constituent molecules, such as polysaccharide A of the Bacteroides fragilis capsule, go together with healthy physiological function. Lessons learned from the gut microbiome suggest that the microbiota of the uterus may potentially modulate immune cell subsets needed for implantation and have implications for tissue morphology. Microbiota can also be crucial in protection against uterine infections by defending their niche and competing with pathogens. Our review highlights the need for well-designed studies on a 'baseline' microbial state of the uterus representing the optimal starting point for implantation and subsequent placenta formation.

WIDER IMPLICATIONS

The complex interplay of processes and cells involved in healthy pregnancy is still poorly understood. The correct receptive endometrial state, including the local immune environment, is crucial not only for fertility but also placenta formation since initiation of placentation highly depends on interaction with immune cells. Implantation failure, recurrent pregnancy loss, and other pathologies of endometrium and placenta, such as pre-eclampsia, represent an increasing societal burden. More robust studies are needed to investigate uterine colonization. Based on current data, future research needs to include the uterine microbiome as a relevant factor in order to understand the players needed for healthy pregnancy.

The immunology of the macaque placenta: A detailed analysis and critical comparison with the human placenta

The cynomolgus monkey is increasingly considered in toxicological research as the most appropriate model for humans due to the species' close physiological contiguity, including reproductive physiology. Here, literature on the cynomolgus monkey placenta is reviewed in regards to its similarity to the human placenta and particularly for its immunological role, which is not entirely mirrored in humans. Pertinent original data are included in this article. The cynomolgus monkey placenta is evaluated based on three aspects: first, morphological development; second, the spatial and temporal appearance of maternal and fetal immune cells and certain immune cell products of the innate and adaptive immune systems; and third, the expression of relevant immune tolerance-related molecules including the homologs of anti-human leucocyte antigen, indoleamine 2,3-dioxygenase, FAS/FAS-L, annexin II, and progesterone. Parameters relevant to the immunological role of the placenta are evaluated from the immunologically immature stage of gestational day (GD) 50 until more mature stages close to birth. Selected comparisons are drawn with human and other laboratory animal placentas. In conclusion, the cynomolgus monkey placenta has a high degree of morphological and physiological similarity to the human placenta. However, there are differences in the topographical distribution of cell types and immune tolerance-related molecules. Three basic features are recognized: (1) the immunological capacity of the placenta changes throughout the lifetime of the organ; (2) these immunological changes include multiple parameters such as morphological adaptations, cell type involvement, and changes in immune-relevant molecule expression; and (3) the immune systems of two genetically disparate individuals (mother and child) are functionally intertwined at the maternal-fetal interface.

Human decidua mesenchymal stem cells regulate decidual natural killer cell function via interactions between collagen and leukocyte‑associated immunoglobulin‑like receptor 1

The development of maternal tolerance to the fetal allograft in critical for the maintenance of the pregnancy, and it is accompanied by the development of a special decidual natural killer (dNK) cell tolerance phenotype. To understand the factors that influence dNK cells during early pregnancy, the present study aimed to identify mesenchymal stem cells (MSCs) from human first‑trimester deciduas, termed decidual MSCs (DMSCs), and to investigate the effect of DMSCs on the regulation of dNK cells via collagen. Decidual samples were collected from women with normal pregnancy that had undergone elective vaginal surgical terminations at 6‑9 weeks gestation. DMSCs derived from human decidual tissues were cultured under differentiation conditions to examine their multipotent differentiation capacities, and the expression of MSC‑specific markers, including cluster of differentiation (CD)44, CD73, CD105, CD90, CD34, CD31, CD14, CD45, CD11b and human leukocyte antigen‑antigen D related, was determined. dNK cells were co‑cultured with DMSCs in order to examine the effect of DMSCs on the tolerance phenotype of dNK cells. The expression of cell surface molecules, natural cytotoxicity triggering receptor 3 and killer cell immunoglobulin‑like receptor (KIR) 2DL1, and the secretion of cytokines, including interferon‑γ, tumor necrosis factor (TNF)‑α, interleukin (IL)‑10, IL‑4 and perforin, were examined by flow cytometry analysis. To determine whether the regulation of dNK cells by DMSCs was mediated by collagen, DMSCs were pre‑treated with human recombinant leukocyte‑associated immunoglobulin‑like receptor (LAIR)‑2 and transfected with pScoR‑GFP‑hP4H to inhibit the interaction between LAIR‑1 and collagen. The present results demonstrated that collagen produced by DMSCs increased the expression of KIR2DL1 and IL‑4, decrease the expression of NKp30 and TNF‑α. In conclusion, the results of the present study demonstrated that DMSCs may be cultured in vitro for prolonged periods, whilst retaining the ability to differentiate into different cell lineages. In addition, DMSCs may modulate the function of dNK cells via the interaction between collagen and LAIR‑1.

Extracellular vesicles in blood, milk and body fluids of the female and male urogenital tract and with special regard to reproduction

Extracellular vesicles (EVs) are released from almost all cells and tissues. They are able to transport substances (e.g. proteins, RNA or DNA) at higher concentrations than in their environment and may adhere in a receptor-controlled manner to specific cells or tissues in order to release their content into the respective target structure. Blood contains high concentrations of EVs mainly derived from platelets, and, at a smaller amount, from erythrocytes. The female and male reproductive tracts produce EVs which may be associated with fertility or infertility and are released into body fluids and mucosas of the urogenital organs. In this review, the currently relevant detection methods are presented and critically compared. During pregnancy, placenta-derived EVs are dynamically detectable in peripheral blood with changing profiles depending upon progress of pregnancy and different pregnancy-associated pathologies, such as preeclampsia. EVs offer novel non-invasive diagnostic tools which may reflect the situation of the placenta and the foetus. EVs in urine have the potential of reflecting urogenital diseases including cancers of the neighbouring organs. Several methods for detection, quantification and phenotyping of EVs have been established, which include electron microscopy, flow cytometry, ELISA-like methods, Western blotting and analyses based on Brownian motion. This review article summarises the current knowledge about EVs in blood and cord blood, in the different compartments of the male and female reproductive tracts, in trophoblast cells from normal and pre-eclamptic pregnancies, in placenta ex vivo perfusate, in the amniotic fluid, and in breast milk, as well as their potential effects on natural killer cells as possible targets.

Human monocytes undergo functional re-programming during differentiation to dendritic cell mediated by human extravillous trophoblasts

Maternal immune adaptation is required for a successful pregnancy to avoid rejection of the fetal–placental unit. Dendritic cells within the decidual microenvironment lock in a tolerogenic profile. However, how these tolerogenic DCs are induced and the underlying mechanisms are largely unknown. In this study, we show that human extravillous trophoblasts redirect the monocyte-to-DC transition and induce regulatory dendritic cells. DCs differentiated from blood monocytes in the presence of human extravillous trophoblast cell line HTR-8/SVneo displayed a DC-SIGN⁺CD14⁺CD1a⁻ phenotype, similar with decidual DCs. HTR8-conditioned DCs were unable to develop a fully mature phenotype in response to LPS, and altered the cytokine secretory profile significantly. Functionally, conditioned DCs poorly induced the proliferation and activation of allogeneic T cells, whereas promoted CD4⁺CD25⁺Foxp3⁺ Treg cells generation. Furthermore, the supernatant from DC and HTR-8/SVneo coculture system contained significant high amount of M-CSF and MCP-1. Using neutralizing antibodies, we discussed the role of M-CSF and MCP-1 during monocyte-to-DCs differentiation mediated by extravillous trophoblasts. Our data indicate that human extravillous trophoblasts play an important role in modulating the monocyte-to-DC differentiation through M-CSF and MCP-1, which facilitate the establishment of a tolerogenic microenvironment at the maternal–fetal interface.

Inflammation and preterm birth

Preterm birth is the leading cause of neonatal morbidity and mortality. Although the underlying causes of pregnancy-associated complication are numerous, it is well established that infection and inflammation represent a highly significant risk factor in preterm birth. However, despite the clinical and public health significance, infectious agents, molecular trigger(s), and immune pathways underlying the pathogenesis of preterm birth remain underdefined and represent a major gap in knowledge. Here, we provide an overview of recent clinical and animal model data focused on the interplay between infection-driven inflammation and induction of preterm birth. Furthermore, here, we highlight the critical gaps in knowledge that warrant future investigations into the interplay between immune responses and induction of preterm birth.

Parallel Expression of Enzyme Inhibitors of CD8T Cell Activity in Tumor Microenvironments and Secretory Endometrium

The divergent requirement for tolerance to support conception and protective response against sexually transmitted infections defines the unique immunological dynamics in the female reproductive tract (FRT). In part, these requirements are achieved by the cyclic modulation of cytolytic CD8T cell function in the FRT that underlie the respective immunosuppressive and immunocompetent milieus during the secretory and proliferative phases of the menstrual cycle. The CD8T cell function can be dampened by exposure to indoleamine 2,3-dioxygenase and/or arginase enzymes. Indeed, these 2 enzymes are known as primary inducers of immune suppression in tumor microenvironments. This review discusses the intriguing parallel expression of these 2 enzymes in tumor microenvironments and in the secretory endometrium. We surmise that investigating the underlying natural mechanisms that suppress and restore the immunocompetence of CD8T cells in the FRT each month may provide valuable insights into ways to artificially recapitulate these mechanisms and inhibit immune suppression in tumor microenvironments.

Progestin-Containing Contraceptives Alter Expression of Host Defense-Related Genes of the Endometrium and Cervix

Epidemiological studies indicate that progestin-containing contraceptives increase susceptibility to HIV, although the underlying mechanisms involving the upper female reproductive tract are undefined. To determine the effects of depot medroxyprogesterone acetate (DMPA) and the levonorgestrel intrauterine system (LNG-IUS) on gene expression and physiology of human endometrial and cervical transformation zone (TZ), microarray analyses were performed on whole tissue biopsies. In endometrium, activated pathways included leukocyte chemotaxis, attachment, and inflammation in DMPA and LNG-IUS users, and individual genes included pattern recognition receptors, complement components, and other immune mediators. In cervical TZ, progestin treatment altered expression of tissue remodeling and viability but not immune function genes. Together, these results indicate that progestins influence expression of immune-related genes in endometrium relevant to local recruitment of HIV target cells with potential to increase susceptibility and underscore the importance of the upper reproductive tract when assessing the safety of contraceptive products.

M1/M2 macrophage polarity in normal and complicated pregnancy

Tissue macrophages play an important role in all stages of pregnancy, including uterine stromal remodeling (decidualization) before embryo implantation, parturition, and post-partum uterine involution. The activation state and function of utero-placental macrophages are largely dependent on the local tissue microenvironment. Thus, macrophages are involved in a variety of activities such as regulation of immune cell activities, placental cell invasion, angiogenesis, and tissue remodeling. Disruption of the uterine microenvironment, particularly during the early stages of pregnancy (decidualization, implantation, and placentation) can have profound effects on macrophage activity and subsequently impact pregnancy outcome. In this review, we will provide an overview of the temporal and spatial regulation of utero-placental macrophage activation during normal pregnancy in human beings and rodents with a focus on more recent findings. We will also discuss the role of M1/M2 dysregulation within the intrauterine environment during adverse pregnancy outcomes.

Crystallin αB acts as a molecular guard in mouse decidualization: regulation and function during early pregnancy

Although decidualization is crucial for the establishment of successful pregnancy, the molecular mechanism underlying decidualization remains poorly understood. Crystallin αB (CryAB), a small heat shock protein (sHSP), is up-regulated and phosphorylated in mouse decidua. In mouse primary endometrial stromal cells, CryAB is induced upon progesterone treatment via HIF1α. In addition, CryAB is strongly phosphorylated through the p38-MAPK pathway under stress or during in vitro decidualization. Knockdown of CryAB results in the increase of apoptosis of stromal cells and inhibits decidualization under oxidative or inflammatory stress. Our data indicate that CryAB protects decidualization against stress conditions.

The placenta in toxicology. Part IV: Battery of toxicological test systems based on human placenta

This review summarizes the potential and also some limitations of using human placentas, or placental cells and structures for toxicology testing. The placenta contains a wide spectrum of cell types and tissues, such as trophoblast cells, immune cells, fibroblasts, stem cells, endothelial cells, vessels, glands, membranes, and many others. It may be expected that in many cases the relevance of results obtained from human placenta will be higher than those from animal models due to species specificity of metabolism and placental structure. For practical and economical reasons, we propose to apply a battery of sequential experiments for analysis of potential toxicants. This should start with using cell lines, followed by testing placenta tissue explants and isolated placenta cells, and finally by application of single and dual side ex vivo placenta perfusion. With each of these steps, the relative workload increases while the number of feasible repeats decreases. Simultaneously, the predictive power enhances by increasing similarity with in vivo human conditions. Toxic effects may be detected by performing proliferation, vitality and cell death assays, analysis of protein and hormone expression, immunohistochemistry or testing functionality of signaling pathways, gene expression, transport mechanisms, and so on. When toxic effects appear at any step, the subsequent assays may be cancelled. Such a system may be useful to reduce costs and increase specificity in testing questionable toxicants. Nonetheless, it requires further standardization and end point definitions for better comparability of results from different toxicants and to estimate the respective in vivo translatability and predictive value.

The placenta in toxicology. Part I: Animal models in toxicology: placental morphology and tolerance molecules in the cynomolgus monkey (Macaca fascicularis)

The immune system represents a key defense mechanism against potential pathogens and adverse non-self materials. During pregnancy, the placenta is the point of contact between the maternal organism and non-self proteins of the fetal allograft and hence undoubtedly fulfils immune functions. In the placenta bacteria, foreign (non-self) proteins and proteins that might be introduced in toxicological studies or by medication are barred from reaching the progeny, and the maternal immune system is primed for acceptance of non-maternal fetal protein. Both immunologic protection of the fetus and acceptance of the fetus by the mother require effective mechanisms to prevent an immunologic fetomaternal conflict and to keep both organisms in balance. This is why the placenta requires toxicological consideration in view of its immune organ function. The following articles deal with placenta immune-, control-, and tolerance mechanisms in view of both fetal and maternal aspects. Furthermore, models for experimental access to placental immune function are addressed and the pathological evaluation is elucidated. "The Placenta as an Immune Organ and Its Relevance in Toxicological Studies" was subject of a continuing education course at the 2012 Society of Toxicologic Pathology meeting held in Boston, MA.

Gene expression and DNA-methylation of bovine pretransfer endometrium depending on its receptivity after in vitro-produced embryo transfer

Embryonic implantation to establish a pregnancy is a complex process that requires appropriate communication between the embryo and the maternal endometrium. Inadequate uterine receptivity may contribute to the majority of implantation failures. To provide a comprehensive inventory of genes and functional networks that represent the maternal input of the embryo-maternal cross-talk, a longitudinal, holistic study of the endometrial transcriptome in relation to the days of estrous and to the receptivity of the endometrium was performed in bovine. At day 3 of estrous, genes related to cell communication and mitochondrial energy metabolism were differentially expressed among high- and low-receptive endometria (HR, LR); at day 7, transcripts functioning in immune and inflammatory pathways, oxidative stress, and angiogenesis had different abundances. Additionally, temporal transcriptional changes between days 3 and 7 differed considerably among HR and LR. Further, several transcription factors were predicted as relevant for receptivity because they were either differentially expressed among HR and LR animals or are known to be associated with genes we detected to have differential expression. Finally, global DNA methylation varied according to the interaction of receptivity group and day of estrous, and a divergent trend, which correlated with abundance of DNMT1 transcript, was observed in LR and HR along the estrous cycle days. The study revealed that, even in early estrous, transcripts related to cell communication and response to exogenous stimuli, vascularization, and energy supply show divergent expression and longitudinal temporal regulation in HR and LR. Key components of these molecular pathways are known to be dependent on ovarian hormones that promote uterine receptivity.

The expressions of CD200 and CD200R molecules on myeloid and lymphoid dendritic cells in pre-eclampsia and normal pregnancy

PROBLEM

The purpose of our study was to test the hypothesis that the expressions of CD200 and CD200R tolerance molecules are increased on peripheral blood dendritic cells (DCs) in normal pregnancy and decreased on peripheral blood DCs in pre-eclampsia.

METHOD OF STUDY

Thirty-three patients with pre-eclampsia, 38 normal pregnant women, and 10 healthy non-pregnant women were included in the study. Dendritic cells were isolated from peripheral blood, stained with monoclonal antibodies against blood dendritic cell antigens as well as CD200 and CD200R antigens, and estimated using flow cytometry.

RESULTS

The expressions of CD200 and CD200R molecules on CD1c(+) myeloid and BDCA-2(+) lymphoid DCs in the first trimester of normal pregnancy were significantly higher when compared to the luteal phase of the ovarian cycle. The expressions of CD200 molecule on CD1c(+) myeloid DCs were significantly lower in the third trimester of normal pregnancy when compared to the second trimester. The expressions of CD200R molecule on CD1c(+) myeloid DCs and BDCA-2(+) lymphoid DCs did not differ in pre-eclampsia and healthy third trimester pregnant women. However, the expressions of CD200 molecule on CD1c(+) myeloid and BDCA-2(+) lymphoid DCs were significantly higher in pre-eclampsia when compared to the healthy third trimester pregnant women.

CONCLUSION

The results suggest increased tolerogenic properties of myeloid and lymphoid DCs in normal human pregnancy. Moreover, they suggest a decrease in tolerogenic properties of DCs before delivery. It seems possible that higher expressions of CD200 molecule on CD1c(+) myeloid and BDCA-2(+) lymphoid DCs in pre-eclampsia may constitute the tolerogenic mechanism secondary to the pro-inflammatory response that is observed in this syndrome.

Endometrial receptivity and human embryo implantation

PROBLEM

The pre-requisite of successful implantation involves an intricate cascade of molecular interactions which plays a crucial role in preparing receptive endometrium and implanting blastocyst.

METHOD OF STUDY

Data are hereby presented for a better understanding of endometrial receptivity in women, hoping to provide a comprehensive picture of the process and identify new areas of basic and translational research in the biology of blastocyst implantation.

RESULTS

Timely regulation of the expression of a number of complex molecules like hormones, cytokines and growth factors, and their crosstalk from embryonic and maternal endometrial side play a major role in determining the fate of the embryo. The molecular basis of endometrial receptivity and the mechanisms by which the blastocyst first adheres to the luminal epithelium and then penetrates into the stroma are only just beginning to be resolved.

CONCLUSION

Advances in the development of implantation models and 'omics' technologies, particularly proteomics and metabolomics, are set to have a major impact on the development of this field.

Antigen-presenting cells in pregnant and non-pregnant human myometrium

PROBLEM

Inflammatory cells play a crucial role in human parturition. Different populations of leucocytes invade the reproductive tract. Numerous studies have described the decidual immune cell population in pregnant and non-pregnant endometrium. However, little is known about the presence of immune cells in human myometrium.

METHOD OF STUDY

we herein analysed a spectrum of immune cells in human myometrium comparing tissue samples from non-pregnant (n = 8) and pregnant (n = 10) uteri. Applying immunohistochemistry with a panel of antibodies specific for T cells, monocytes, natural killer cells, B cells and antigen-presenting cells (CD4, CD8, CD14, CD15, CD16, CD19, CD56, CD68, CD83, HLA-DR, DC-Sign, mast cell tryptase), we characterized the immune cell population of human myometrium.

RESULTS

a significantly higher number of CD14, CD15, CD16, DC-SIGN as well as CD4-positive cells were found in myometrium of pregnant compared to non-pregnant uteri, while mast cells were significantly reduced in pregnant myometrium.

CONCLUSION

all markers found increased in pregnant myometrium indicate monocyte/macrophage lineage cells and thus suggest a possible involvement of these cells in healthy pregnancy maintenance. Monocytes/macrophages might produce a microenvironment that permits a controlled invasion of trophoblast cells into the myometrium while preventing a rejection of the semiallogenic conceptus and providing an important barrier against invading pathogenes.

Immature NK cells, capable of producing IL-22, are present in human uterine mucosa

NK cells are the dominant population of immune cells in the endometrium in the secretory phase of the menstrual cycle and in the decidua in early pregnancy. The possibility that this is a site of NK cell development is of particular interest because of the cyclical death and regeneration of the NK population during the menstrual cycle. To investigate this, we searched for NK developmental stages 1-4, based on expression of CD34, CD117, and CD94. In this study, we report that a heterogeneous population of stage 3 NK precursor (CD34(-)CD117(+)CD94(-)) and mature stage 4 NK (CD34(-)CD117(-/+)CD94(+)) cells, but not multipotent stages 1 and 2 (CD34(+)), are present in the uterine mucosa. Cells within the uterine stage 3 population are able to give rise to mature stage 4-like cells in vitro but also produce IL-22 and express RORC and LTA. We also found stage 3 cells with NK progenitor potential in peripheral blood. We propose that stage 3 cells are recruited from the blood to the uterus and mature in the uterine microenvironment to become distinctive uterine NK cells. IL-22 producers in this population might have a physiological role in this specialist mucosa dedicated to reproduction.

Human uterine epithelial cell secretions regulate dendritic cell differentiation and responses to TLR ligands

The balance between immunity and tolerance in the endometrium is governed by dynamic interactions of UEC and immune cells including DC. In this study, we tested the hypothesis that soluble immune mediators secreted by UEC modulate the differentiation and functions of human DC. We found that DC differentiated with CM from polarized UEC (i.e., CM-DC) expressed significantly lower surface CD86. Upon activation with LPS or PIC, the expression of CD80, CD86, and CD83 was decreased significantly on CM-DC relative to Con-DC. Further, mRNA for TLR3, TLR4, and TLR5 was decreased significantly in CM-DC relative to Con-DC. As a functional read-out of the effect of CM on DC, we determined the following parameters: First, analysis of cytokine production showed that when compared with Con-DC, CM-DC responded to LPS or PIC stimulation with enhanced IL-10 production but undetectable IL-12p70 secretion. Second, RT-PCR analysis showed that CM-DC significantly expressed higher mRNA for IDO, an immune tolerance-promoting enzyme. Lastly, in a MLR assay, CM-DC induced significantly lower allogeneic proliferative responses compared with Con-DC. These findings indicate collectively that epithelial cells confer a tolerogenic phenotype to DC in the endometrium. Our results suggest novel cellular and molecular mechanisms for the regulation of adaptive immunity within the FRT.

Proteomics of embryonic implantation

Implantation is a complex process involving an intricate cascade of molecular interactions between the implanting blastocyst and the receptive endometrium. The molecular basis of endometrial receptivity and the mechanisms by which the blastocyst first adheres to the luminal epithelium and then penetrates into the stroma are only just beginning to be resolved. Advances in "omics" technologies, particularly proteomics and metabolomics, are set to have a major impact on the development of this field. In the wake of this information, novel targets for contraceptive intervention may become apparent.

The a2 isoform of vacuolar ATPase is a modulator of implantation and feto-maternal immune tolerance in early pregnancy

In mammalian reproduction, two immunologically disparate entities, the mother and her fetus, co-exist in close proximity and mutually tolerate each other. The maternal immune system plays a major contributing role in the reproductive outcome. A coordinated set of immunological events takes place between the maternal and fetal cells to ensure fetal survival. Among these, cytokines secreted by proximal maternal immune cells as well as fetal trophoblast cells play a major role in feto-maternal tolerance. In this review, we describe the role of the vacuolar ATPase (and more specifically the a2 isoform, a2V-ATPase) in controlling the expression of these vital cytokines. a2V-ATPase is a key enzyme that controls the acidification of intracellular vesicles and the extracellular environment, processes that play a major role in cellular function. The localization of a2V-ATPase in tissues and immune cells of the reproductive tract which are essential for pregnancy will be described. Information will be provided on the role of a2V-ATPase on aspects of cell development in pregnancy, from fertilization to implantation and fetal growth. Particular emphasis will be placed on the role of a2V-ATPase in (a) regulating parts of the cytokine network at the implantation site and (b) attenuating the potentially harmful maternal immune response against trophoblast cells.

Cells with haematopoietic stem cell phenotype in adult human endometrium: relevance to infertility?

BACKGROUND

Uterine lymphoid cell repertoires are specialized in order to meet the twin demands of successful pregnancy and local immunosurveillance. The possibility that some of these populations might differentiate locally from progenitor cells has been proposed.

METHODS

Endometrial tissue from women with a history of infertility as well as fertile controls was examined for haematopoietic stem cells (HSCs) and lymphoid progenitors using three-colour flow cytometry.

RESULTS

Significant populations of phenotypic HSCs (CD34+ CD45+ ) were detected in all samples, a high proportion of which co-expressed the differentiation marker CD45RA (45.7%), indicating ongoing differentiation. Almost 30% of uterine HSCs co-expressed CD56 and 44% co-expressed CD7, suggesting the presence of lymphoid progenitors. Small proportions expressed CD127 and CD122, receptors for interleukin (IL)-7 and IL-15, respectively. HSC numbers were similar in the endometrial samples from fertile and infertile women. However, the proportion co-expressing the natural killer (NK) antigen CD56 was significantly increased compared with HSCs found in the endometrium of fertile controls (P = 0.002).

CONCLUSIONS

This is the first demonstration of cells with an HSC phenotype in the human endometrium, and increased proportions of NK progenitors in endometrium of women with infertility suggests a dysregulation of this pathway that may contribute to infertility.

Inhibition of term decidual NK cell cytotoxicity by soluble HLA-G1

OBJECTIVES

Soluble (s)HLA-G1 is produced by trophoblast cells. Aim was to analyze the capacities and mechanisms of sHLA-G1 to regulate interleukin (IL)-2-induced cytotoxicity of natural killer (NK) cells from human deciduas.

METHODS

Natural killer cells were isolated from decidual layers of term placentae, stimulated or not with IL-2 and supplemented with various concentrations of recombinant soluble HLA-G1 (sHLA-G1). For NK cell cytotoxicity assays, K562 cells were used as targets. Expression of signal transducer and activator of transcription 3 (STAT3) and perforin was analyzed by Western blotting. Apoptosis was examined by assessment of poly(ADP-ribose) polymerase cleavage. NK cells were analyzed by flow cytometry for IL-2receptor-alpha (IL-2R alpha; CD25) and transferrin receptor CD71 expression.

RESULTS

Interleukin-2 increases CD71, STAT3, perforin expression and cytotoxic potential of NK cells. Expression of CD71, STAT3 and perforin decreased simultaneously with cytotoxicity and dose-dependently when sHLA-G1 (1.6 micro g/mL-1.6 ng/mL) was added to IL-2 stimulated cultures. sHLA-G1 did not induce apoptosis and CD25 expression was not affected.

CONCLUSION

Interleukin-2R alpha expression is not controlled by sHLA-G1, but its signal transducer STAT3 as well as several downstream effects, such as perforin expression, proliferation and cytotoxicity. The control of STAT3 bioavailability through sHLA-G1 may be a key regulator of the mentioned effects.