Hormonal regulation of uterine chemokines and immune cells

Unveiling the Role of Endometrial CD-138: A Comprehensive Review on Its Significance in Infertility and Early Pregnancy

This review comprehensively examines the role of endometrial CD-138 (syndecan-1) in the context of infertility and early pregnancy. The endometrium, a dynamic tissue responsive to hormonal cues, plays a central role in fertility, and understanding the molecular intricacies governing its function is crucial. CD-138, a cell surface proteoglycan, emerges as a critical player expressed by various endometrial cell types. Our exploration encompasses a brief overview of the endometrium, introducing CD-138 as a significant molecular entity. The rationale for the review underscores the importance of elucidating endometrial factors in fertility and addresses existing knowledge gaps related to CD-138. Throughout the review, we unravel the multifaceted nature of CD-138 and its involvement in infertility, highlighting its potential as a diagnostic marker. Furthermore, insights into CD-138's role during early pregnancy, including trophoblast-endothelial interactions, are discussed. In conclusion, the findings underscore the clinical implications of CD-138, suggesting its utility in diagnostics and offering prospects for targeted therapeutic interventions. The identified knowledge gaps propel future research directions, promising to deepen our understanding of this enigmatic molecule and its transformative potential in reproductive medicine.

Impact of body mass index on peripheral and uterine immune status in the window of implantation in patients with recurrent reproductive failure

This study aimed to investigate whether maternal obesity affects the immune status of peripheral blood and endometrium in patients with recurrent reproductive failure classified according to their body mass index (BMI). A total of 228 repeated implantation failure (RIF) and 266 recurrent miscarriage (RM) patients were enrolled in the study and further subdivided into three groups according to their BMI: (i) normal weight (18.5≤ BMI <23); (ii) overweight (23≤ BMI <25); and (iii) obese (BMI ≥25). Peripheral blood and endometrium samples were collected in the mid-luteal phase before IVF treatment or natural pregnancy. Peripheral immunocytes were analyzed by flow cytometry, while uterine immune cells were subjected to immunohistochemistry. In RM patients, significantly increased peripheral helper T cells and decreased cytotoxic T cells, NK cells were observed in the obese group compared with the normal-weight group. Meanwhile, in the endometrium, the percentage of NK cell, macrophage cell, M2 macrophage cell, and Treg cell significantly reduced with increased BMI in RIF patients, and the percentage of NK cell and M2 macrophage cell significantly decreased with increased BMI in RM patients. In conclusion, obesity may cause endometrial immune disorder in recurrent reproductive failure women, but was only associated with the peripheral immune change in RM patients.

Why Does Your Uterus Become Malignant? The Impact of the Microbiome on Endometrial Carcinogenesis

The aim of this review was to describe the uterine microbiome composition that has been analyzed so far and describe potential pathways in the carcinogenesis of the endometrium. The microbiome in the uterine environment is involved in apoptosis and proliferation during the menstruation cycle, pregnancy maintenance, and immune system support. However, bacteria in the uterus could stimulate inflammation, which when chronic results in malignancy. An altered gut microbiota initiates an inflammatory response through microorganism-associated molecular patterns, which leads to intensified steroidogenesis in the ovaries and cancers. Moreover, intestinal bacteria secreting the enzyme β-glucuronidase may increase the level of circulating estrogen and, as a result, be influential in gynecological cancers. Both the uterine and the gut microbiota play a pivotal role in immune modulation, which is why there is a demand for further investigation from both the diagnostic and the therapeutic perspectives.

Uterine Nodal expression supports maternal immunotolerance and establishment of the FOXP3+ regulatory T cell population during the preimplantation period

Pregnancy success is dependent on the establishment of maternal tolerance during the preimplantation period. The immunosuppressive function of regulatory T cells is critical to limit inflammation arising from implantation of the semi-allogeneic blastocyst. Insufficient maternal immune adaptations to pregnancy have been frequently associated with cases of female infertility and recurrent implantation failure. The role of Nodal, a secreted morphogen of the TGFβ superfamily, was recently implicated during murine pregnancy as its conditional deletion (NodalΔ/Δ) in the female reproductive tract resulted in severe subfertility. Here, it was determined that despite normal preimplantation processes and healthy, viable embryos, NodalΔ/Δ females had a 50% implantation failure rate compared to NodalloxP/loxP controls. Prior to implantation, the expression of inflammatory cytokines MCP-1, G-CSF, IFN-γ and IL-10 was dysregulated in the NodalΔ/Δ uterus. Further analysis of the preimplantation leukocyte populations in NodalΔ/Δ uteri showed an overabundance of infiltrating, pro-inflammatory CD11bhigh Ly6C+ macrophages coupled with the absence of CD4+ FOXP3+ regulatory T cells. Therefore, it is proposed that uterine Nodal expression during the preimplantation period has a novel role in the establishment of maternal immunotolerance, and its dysregulation should be considered as a potential contributor to cases of female infertility and recurrent implantation failure.

Immunology of Pregnancy and Systemic Consequences

Pregnancy is an immunological paradox, with renowned Nobel Prize winning transplantation biologist Sir Peter Brian Medawar being the first to introduce this concept back in 1953. This concept considers how the maternal immune system can tolerate the developing fetus, which is 50% antigenically foreign to the uterus. There have been significant advances in our understanding of the immune system in regulating fertility, pregnancy and in complications of these, and what was once considered a paradox can be seen as a highly evolved system. Indeed, the complexity of the maternal-fetal interface along with our ever-advancing knowledge of immune cells and mediators means that we have a better understanding of these interactions, with gaps still present.  This chapter will summarise the key aspects of the role of the immune system at each stage of pregnancy and highlight the recent advances in our knowledge.

The Role of Microbiota in the Immunopathogenesis of Endometrial Cancer

The female reproductive tract hosts a specific microbiome, which plays a crucial role in sustaining equilibrium and good health. In the majority of reproductive women, the microbiota (all bacteria, viruses, fungi, and other single-celled organisms within the human body) of the vaginal and cervical microenvironment are dominated by Lactobacillus species, which benefit the host through symbiotic relationships, in comparison to the uterus, fallopian tubes, and ovaries, which may contain a low-biomass microbiome with a diverse mixture of microorganisms. Although disruption to the balance of the microbiota develops, the altered immune and metabolic signaling may cause an impact on diseases such as cancer. These pathophysiological modifications in the gut–uterus axis may spark gynecological cancers. New information displays that gynecological and gastrointestinal tract dysbiosis (disruption of the microbiota homeostasis) can play an active role in the advancement and metastasis of gynecological neoplasms, such as cervical, endometrial, and ovarian cancers. Understanding the relationship between microbiota and endometrial cancer is critical for prognosis, diagnosis, prevention, and the development of innovative treatments. Identifying a specific microbiome may become an effective method for characterization of the specific microbiota involved in endometrial carcinogenesis. The aim of this study was to summarize the current state of knowledge that describes the correlation of microbiota with endometrial cancer with regard to the formation of immunological pathologies.

Understanding human immunity in idiopathic recurrent pregnancy loss

Miscarriage, defined as the loss of a pregnancy before a viable gestation, affects 1 in 6 couples. Recurrent pregnancy loss (RPL), defined as two or more miscarriages, affects up to 1.9% of couples. The physical, psychological, and financial impact of miscarriage can be substantial. However, despite its multifactorial etiology, for up to 50% of couples a reason behind this condition cannot be identified, termed 'idiopathic RPL'. Much recent research has strived to understand this, with immune dysregulation being a source of particular interest. In this short review we summarize the current evidence on the complex role of the immune system both pre- and early post-conception in RPL. A key question is whether systemic peripheral blood markers, in particular natural killer cell and T cells, may be utilized to accurately predict and/ or diagnose those pregnancies at high risk of loss. Given the invasive nature of endometrial testing, identification of reliable peripheral immune biomarkers is particularly appealing. Clinical trials using potent immunomodulatory agents, including intravenous immunoglobulin, donor leukocyte immunization, and tumor necrosis factor (TNF)-α inhibitors, have been undertaken with the primary objective of preventing miscarriage in women with RPL. Standardisation of both diagnostic and prognostic immune cell testing assays is required to permit accurate identification of those women who may benefit from immunomodulation. Prompt clarification is required to meet the increasing expectation from couples and clinicians, as without these advancements women are at risk of exposure to potent immune-therapies and subsequent studies are at risk of failure, generating further controversy regarding the role of immune dysregulation in women with RPL. Through this review we highlight clear gaps in our current knowledge on immune activity in RPL.

CXCL5 Downregulation in Villous Tissue Is Correlated With Recurrent Spontaneous Abortion

Recurrent spontaneous abortion (RSA) affects 5% of childbearing-age women worldwide. Inadequate trophoblast invasion is one of the main reasons for the development of RSA; however, the underlying molecular mechanisms for RSA have not been fully understood, and further explanation is urgently needed. C-X-C motif chemokine ligand 5 (CXCL5) is reported to contribute to the invasion of cancer cells, and its aberrant expression is associated with the cellular process of tumor pathology. Considering the high behavioral similarity between trophoblast cells and cancer cells, we hypothesized that CXCL5 may influence trophoblast invasion, and its expression levels in villous tissue may be correlated with RSA. In this study, we firstly investigated the CXCL5 expression in placental villous tissues of 15 RSA patients and 13 control patients, and the results showed that CXCL5 levels were significantly lower in villous tissue from RSA patients than those of the controls. Further in vitro experiments presented that recombinant human CXCL5 can enhance trophoblast migration, invasion, and epithelial-to-mesenchymal transition (EMT) process. We also demonstrated that CXCL5 exerted these effects on trophoblast cells through PI3K/AKT/ERK1/2 signaling pathway. In conclusion, these data indicate that CXCL5 downregulation in human villous tissue is correlated with RSA. Additionally, we found that estrogen, progesterone, human chorionic gonadotropin, and decidual stromal cells can regulate CXCL5 and chemokine receptor 2 (CXCR2) expression of trophoblast in a cell manner.

Detrimental effects of lipopolysaccharide on the attachment and outgrowth of various trophoblastic spheroids on human endometrial epithelial cells

OBJECTIVE

Lipopolysaccharide (LPS) from Gram-negative bacteria causes poor uterine receptivity by inducing excessive inflammation at the maternal-fetal interface. This study aimed to investigate the detrimental effects of LPS on the attachment and outgrowth of various types of trophoblastic spheroids on endometrial epithelial cells (ECC-1 cells) in an in vitro model of implantation.

METHODS

Three types of spheroids with JAr, JEG-3, and JAr mixed JEG-3 (JmJ) cells were used to evaluate the effect of LPS on early implantation events. ECC-1 cells were treated with LPS to mimic endometrial infection, and the expression of inflammatory cytokines and adhesion molecules was analyzed by quantitative real-time polymerase chain reaction and western blotting. The attachment rates and outgrowth areas were evaluated in the various trophoblastic spheroids and ECC-1 cells treated with LPS.

RESULTS

LPS treatment significantly increased the mRNA expression of inflammatory cytokines (CXCL1, IL-8, and IL-33) and decreased the protein expression of adhesion molecules (ITGβ3 and ITGβ5) in ECC-1 cells. The attachment rates of JAr and JmJ spheroids on ECC-1 cells significantly decreased after treating the ECC-1 cells with 1 and 10 μg/mL LPS. In the outgrowth assay, JAr spheroids did not show any outgrowth areas. However, the outgrowth areas of JEG-3 spheroids were similar regardless of LPS treatment. LPS treatment of JmJ spheroids significantly decreased the outgrowth area after 72 hours of coincubation.

CONCLUSION

An in vitro implantation model using novel JmJ spheroids was established, and the inhibitory effects of LPS on ECC-1 endometrial epithelial cells were confirmed in the early implantation process.

The proliferative phase endometrium in IVF/ICSI: an in-cycle molecular analysis predictive of the outcome following fresh embryo transfer

STUDY QUESTION

Does an early proliferative phase endometrial biopsy harvested during ovarian stimulation harbour information predictive of the outcome following fresh embryo transfer (ET) in that same cycle?

SUMMARY ANSWER

Transcriptome analysis of the whole-tissue endometrium did not reveal significant differential gene expression (DGE) in relation to the outcome; however, the secretome profile of isolated, cultured and in vitro decidualized endometrial stromal cells (EnSCs) varied significantly between patients who had a live birth compared to those with an implantation failure following fresh ET in the same cycle as the biopsy.

WHAT IS KNOWN ALREADY

In the majority of endometrial receptivity research protocols, biopsies are harvested during the window of implantation (WOI). This, however, precludes ET in that same cycle, which is preferable as the endometrium has been shown to adapt over time. Endometrial biopsies taken during ovarian stimulation have been reported not to harm the chances of implantation, and in such biopsies DGE has been observed between women who achieve pregnancy versus those who do not. The impact of the endometrial proliferative phase on human embryo implantation remains unclear, but deserves further attention, especially since in luteal phase endometrial biopsies, a transcriptional signature predictive for repeated implantation failure has been associated with reduced cell proliferation, possibly indicating proliferative phase involvement. Isolation, culture and in vitro decidualization (IVD) of EnSCs is a frequently applied basic research technique to assess endometrial functioning, and a disordered EnSC secretome has previously been linked with failed implantation.

STUDY DESIGN, SIZE, DURATION

This study was nested in a randomized controlled trial (RCT) investigating the effect of endometrial scratching during the early follicular phase of ovarian stimulation on clinical pregnancy rates after IVF/ICSI. Of the 96 endometrial biopsies available, after eliminating those without fresh ET and after extensive matching in order to minimize the risk of potential confounding, 18 samples were retained to study two clinical groups: nine biopsies of patients with a live birth versus nine biopsies of patients with an implantation failure, both following fresh ET performed in the same cycle as the biopsy. We studied the proliferative endometrium by analysing its transcriptome and by isolating, culturing and decidualizing EnSCs in vitro. We applied this latter technique for the first time on proliferative endometrial biopsies obtained during ovarian stimulation for in-cycle outcome prediction, in an attempt to overcome inter-cycle variability.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RNA-sequencing was performed for 18 individual whole-tissue endometrial biopsies on an Illumina HiSeq1500 machine. DGE was analysed three times using different approaches (DESeq2, EdgeR and the Wilcoxon rank-sum test, all in R). EnSC isolation and IVD was performed (for 2 and 4 days) for a subset of nine samples, after which media from undifferentiated and decidualized cultures were harvested, stored at -80°C and later assayed for 45 cytokines using a multiplex suspension bead immunoassay. The analysis was performed by partial least squares regression modelling.

MAIN RESULTS AND THE ROLE OF CHANCE

After correction for multiple hypothesis testing, DGE analysis revealed no significant differences between endometrial samples from patients who had a live birth and those with an implantation failure following fresh ET. However secretome analysis after EnSC isolation and culture, showed two distinct clusters that clearly corresponded to the two clinical groups. Upon IVD, the secretome profiles shifted from that of undifferentiated cells but the difference between the two clinical groups remained yet were muted, suggesting convergence of cytokine profiles after decidualization.

LIMITATIONS, REASONS FOR CAUTION

Caution is warranted due to the limited sample size of the study and the in vitro nature of the EnSC experiment. Validation on a larger scale is necessary, however, hard to fulfil given the very limited availability of in-cycle proliferative endometrial biopsies outside a RCT setting.

WIDER IMPLICATIONS OF THE FINDINGS

These data support the hypothesis that the endometrium should be assessed not only during the WOI and that certain endometrial dysfunctionalities can probably be detected early in a cycle by making use of the proliferative phase. This insight opens new horizons for the development of endometrial tests, whether diagnostic or predictive of IVF/ICSI treatment outcome.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by Fonds Wetenschappelijk Onderzoek (FWO, Flanders, Belgium, 11M9415N, 1 524 417N), Wetenschappelijk Fonds Willy Gepts (WFWG G160, Universitair Ziekenhuis Brussel, Belgium) and the National Medicine Research Council (NMRC/CG/M003/2017, Singapore). There are no conflicts of interests.

TRIAL REGISTRATION NUMBER

NCT02061228.

Non-invasive Intrauterine Administration of Botulinum Toxin A Enhances Endometrial Angiogenesis and Improves the Rates of Embryo Implantation

Endometrial angiogenesis plays crucial roles in determining the endometrial receptivity. Defects in endometrial receptivity often cause repeated implantation failure, which is one of the major unmet needs for infertility and contributes a major barrier to the assisted reproductive technology. Despite the numerous extensive research work, there are currently no effective evidence-based treatments to prevent or cure this condition. As a non-invasive treatment strategy, botulinum toxin A (BoTA) was administered into one side of mouse uterine horns, and saline was infused into the other side of horns for the control. Impact of BoTA was assessed in the endometrium at 3 or 8 days after infusion. We demonstrated that BoTA administration enhances the capacity of endothelial cell tube formation and sprouting. The intrauterine BoTA administration significantly induced endometrial angiogenesis displaying increased numbers of vessel formation and expression levels of related marker genes. Moreover, BoTA intrauterine application promoted the endometrial receptivity, and the rates of embryo implantation were improved with BoTA treatment with no morphologically retarded embryos. Intrauterine BoTA treatment has a beneficial effect on vascular reconstruction of functional endometrium prior to embryo implantation by increasing endometrial blood flow near the uterine cavity suggesting BoTA treatment as a potential therapeutic strategy for patients who are suffering from repeated implantation failure with the problems with endometrial receptivity.

Prolonged Effect of Seminal Plasma on Global Gene Expression in Porcine Endometrium

Seminal plasma (SP) deposited in the porcine uterine tract at the time of mating is known to elicit an initial response that is beneficial for pregnancy outcome. However, whether SP has any long-term effect on alterations in endometrial molecular and cellular processes is not known. In this study, using microarray analyses, differential changes in endometrial transcriptome were evaluated after Day 6 of SP-infusion (6DPI) or Day 6 of pregnancy as compared to corresponding day of estrous cycle. Both, pregnancy and SP induced significant changes in the endometrial transcriptome and most of these changes were specific for a particular group. Functional analysis of differentially expressed genes (DEGs) using Ingenuity Pathway Analysis revealed that inhibition in immune response was affected by both pregnancy and SP infusion. Long-term effects of SP included differential expression of genes involved in inhibition of apoptosis, production of reactive oxygen species and steroid biosynthesis, and activation of processes such as proliferation of connective tissue cells and microvascular endothelial cells. Moreover, interleukin-2 and interferon-γ was identified to be responsible for regulating expression of many DEGs identified on 6DPI. The present study provides evidence for the long-term effects of SP on porcine endometrium that can be beneficial for pregnancy success.

Recent Insights on the Maternal Microbiota: Impact on Pregnancy Outcomes

Hormonal changes during and after pregnancy are linked with modifications in the maternal microbiota. We describe the importance of the maternal microbiota in pregnancy and examine whether changes in maternal microbiotic composition at different body sites (gut, vagina, endometrium) are associated with pregnancy complications. We analyze the likely interactions between microbiota and the immune system. During pregnancy, the gastrointestinal (gut) microbiota undergoes profound changes that lead to an increase in lactic acid-producing bacteria and a reduction in butyrate-producing bacteria. The meaning of such changes needs clarification. Additionally, several studies have indicated a possible involvement of the maternal gut microbiota in autoimmune and lifelong diseases. The human vagina has its own microbiota, and changes in vaginal microbiota are related to several pregnancy-related complications. Recent studies show reduced lactobacilli, increased bacterial diversity, and low vaginal levels of beta-defensin 2 in women with preterm births. In contrast, early and healthy pregnancies are characterized by low diversity and low numbers of bacterial communities dominated by Lactobacillus. These observations suggest that early vaginal cultures that show an absence of Lactobacillus and polymicrobial vaginal colonization are risk factors for preterm birth. The endometrium is not a sterile site. Resident endometrial microbiota has only been defined recently. However, questions remain regarding the main components of the endometrial microbiota and their impact on the reproductive tract concerning both fertility and pregnancy outcomes. A classification based on endometrial bacterial patterns could help develop a microbiota-based diagnosis as well as personalized therapies for the prevention of obstetric complications and personalized treatments through nutritional, microbiotic, or pharmaceutical interventions.

Association between rs1049174 NKG2D gene polymorphism and idiopathic recurrent spontaneous abortion in Iranian women: a case-control study

Natural killer group 2, member D (NKG2D) is one of the best known activating receptors of NK cells, which recognises its ligand on altered or stressed cells and activates NK cells to kill them. In this study, the single nucleotide polymorphism of the NKG2D gene for rs1049174 mutation was compared in 140 women with recurrent spontaneous abortion (RSA) and 175 control women with at least one successful pregnancy and without any known pregnancy loss. The findings just revealed that GG genotype and G allele were significantly higher in the case group compared with the control group (p < .001). Our results regarding decreased risk of RSA in C allele (OR = 0.438; 95%CI = 0.310-0.619; p < .001), and GC genotype (OR = 0.492; 95%CI = 0.214-0.574; p < .001) compared with G allele and GG genotype respectively. This study demonstrated a significant association between NKG2D gene polymorphism (rs1049174 G/C) and the risk of RSA in Iranian women.Impact statementWhat is already known on this subject? According to previous investigations, maternal immune responses may affect the foetus, causing recurrent spontaneous abortion (RSA). The main cause of RSA has not yet been detected in nearly 50% of the cases.What do the results of this study add? The results showed that the frequency of G allele and C allele were significantly different in the case group and control group.What are the implications of these findings for clinical practice and/or further research? The results suggest a protective function of C allele because it significantly decreased the risk of RSA compared to G allele. It improves inhibition of NK cells and probably participates in maintaining pregnancy in fertile controls; whereas, G allele is related to a slight inhibition of NK cells, probably leading to increase effectiveness of NK activation and undesirable inflammation, which consequently causes foetal rejection.

Pharmacological blockage of the CXCR4-CXCL12 axis in endometriosis leads to contrasting effects in proliferation, migration, and invasion

High levels of inflammatory factors including chemokines have been reported in peritoneal fluid and blood of women with endometriosis. CXCL12 mediates its action by interaction with its specific receptor, CXCR4, reported to be elevated in human endometriosis lesions and in the rat model of endometriosis. Activation of the CXCR4-CXCL12 axis increases cell proliferation, migration, and invasion of cancer cells. To obtain insights into the CXCR4 expression profile in lesions and endometrium, as well as functionality of the CXCR4-CXCL12 axis in endometriosis, we analyzed the expression of CXCR4 in tissues on a human tissue array and studied CXCL12-mediated activation of proliferation, invasion, and migration in vitro. We observed differences in levels of nuclear CXCR4 expression among lesion types, being higher in ovarian lesions. Endometriotic cell lines (12Z) showed higher levels of CXCR4, proliferative and migratory potential, and AKT phosphorylation/kinase activity compared to untreated control cells (endometrial epithelial cells). CXCL12 and endometriotic stromal cell-enriched media increased proliferation of non-endometriotic epithelial cells. CXCL12 caused a significant increase in 12Z cell invasion but had no effect on migration; AMD3100, a CXCR4-specific inhibitor, significantly increased invasion of 12Z cells but decreased their migration. However, treatment with CXCL12 plus AMD3100 significantly decreased invasion and migration of 12Z cells. In conclusion, the CXCR4-CXCL12 axis is functional in endometriosis cells, but the expression of CXCR4 varies among lesions. CXCL12 promoted proliferation, migration, and invasion of endometriotic cells, while inducing AKT phosphorylation and activity, but pharmacologically blocking this axis in the absence of the ligand induced their invasiveness.

New models of lipopolysaccharide-induced implantation loss reveal insights into the inflammatory response

PROBLEM

Chronic endometritis, inflammation of the uterizzvvne lining caused by common gram-negative bacterial strains or mycoplasma, has been associated with unexplained implantation failure and infertility. However, limited models of bacteria-induced implantation loss exist to study the molecular changes that occur in vivo. The goal of this study was to provide a new resource to study the process of bacteria-induced inflammation and implantation loss utilizing common experimental models: C57Bl/6 mice and primary human endometrial stromal cells.

METHOD OF STUDY

Prior to implantation, mated C57Bl/6 females were administered vehicle (saline) or gram-negative bacterial lipopolysaccharide (LPS) at a range of concentrations by intraperitoneal injection. Implantation sites were counted, and uteri were harvested to evaluate the molecular changes that accompany LPS-mediated implantation loss. Primary human endometrial stromal cells were decidualized in vitro in the presence and absence of LPS. Total RNA and conditioned media were harvested to evaluate the expression of known decidualization-associated genes and various cytokines and chemokines.

RESULTS

Lipopolysaccharide treatment resulted in fewer implantation sites in mice, decreased expression of decidualization-associated genes, and altered expression and release of cytokines and chemokines. Immunohistological analysis of the uterus from LPS-exposed mice demonstrated increased apoptosis and decreased proliferation during decidualization.

CONCLUSION

Lipopolysaccharide exposure disrupted implantation and decidualization in mice and human endometrial stromal cells. This model could be used to study the pathophysiology of implantation failure in patients with chronic endometritis or to test potential therapeutic interventions.

Endometrial microbes and microbiome: Recent insights on the inflammatory and immune "players" of the human endometrium

In recent years, extended scientific works shed light on the important role played by the endometrium in early pregnancy. This review examines our current knowledge about the delicate balance between microbial and cellular immune agents at endometrial level: All of them might affect endometrial receptivity. In contrast to the classical thinking of human endometrium as a sterile tissue, several recent studies have drawn attention to a resident population of microorganisms, which reaches only a 30% of concordance with those of the cervical-vaginal flora. At present, the understanding of the microbiome in relation to human reproduction is in its infancy and further studies are needed to clarify the activity of endometrial microbiome and the possible effects of a "reproductive tract dysbiosis" on fertility. Moreover, in the human endometrium, there is a complex system works preventing the risk of infection as well as enabling, when pregnancy occurs, the acceptance of the blastocyst. In this way, the endometrium plays a central role in the uterine immune surveillance. A better understanding of the different agents that may affect endometrial receptivity would improve the diagnosis and treatment of obstetric complications related to defective implantation and placentation.

Opposing roles of inter-α-trypsin inhibitor heavy chain 4 in recurrent pregnancy loss

Background

The mechanism behind an increased risk of recurrent pregnancy loss (RPL) remains largely unknown. In our previous study, we identified that inter-α-trypsin inhibitor heavy chain 4 (ITI-H4) is highly expressed at a modified molecular weight of 36 kDa in serum derived from RPL patients. Yet, the precise molecular mechanism and pathways by which the short form of ITI-H4 carries out its function remain obscure.

Methods

Human sera and peripheral blood mononucleated cells (PBMCs) were collected from patients and normal controls to compare the expression levels of ITI-H4 and plasma kallikrein (KLKB1). Flow cytometric assay was performed to measure inflammatory markers in sera and culture supernatants. Furthermore, to investigate the functions of the two isoforms of ITI-H4, we performed migration, invasion, and proliferation assays.

Findings

In the current study, we showed that ITI-H4 as a biomarker of RPL could be regulated by KLKB1 through the IL-6 signaling cascade, indicating a novel regulatory system for inflammation in RPL. In addition, our study indicates that the two isoforms of ITI-H4 possess opposing functions on immune response, trophoblast invasion, and monocytes migration or proliferation.

Interpretation

The ITI-H4 (∆N⁶⁸⁸) might be a crucial inflammatory factor which contributes to the pathogenesis of RPL. Moreover, it is expected that this study would give some insights into potential functional mechanisms underlying RPL.

Fund

This study was supported by the Ministry of Health & Welfare of the Republic of Korea (HI18C0378) through the Korea Health Industry Development Institute.

Decidual-Placental Immune Landscape During Syngeneic Murine Pregnancy

Adaptive immune system, principally governed by the T cells-dendritic cells (DCs) nexus, is an essential mediator of gestational fetal tolerance and protection against infection. However, the exact composition and dynamics of DCs and T cell subsets in gestational tissues are not well understood. These are controlled in human physiology by a complex interplay of alloantigen distribution and presentation, cellular/humoral active and passive tolerance, hormones/chemokines/angiogenic factors and their gradients, systemic and local microbial communities. Reductive discrimination of these factors in physiology and pathology of model systems and humans requires simplification of the model and increased resolution of interrogative technologies. As a baseline, we have studied the gestational tissue dynamics in the syngeneic C57BL/6 mice, as the simplest immunological environment, and focused on validating the approach to increased data density and computational analysis pipeline afforded by highly polychromatic flow cytometry and machine learning interpretation. We mapped DC and T cell subsets, and comprehensively examined their maternal (decidual)-fetal (placental) interface dynamics. Both frequency and composition of decidual DCs changed across gestation, with a dramatic increase in myeloid DCs in early pregnancy, and exclusion of plasmacytoid DCs. CD4+ T cells, in contrast, were lower at all gestational ages and an unusual CD4-CD8-TCRαβ+group was prominent at mid-pregnancy. Dimensionality reduction with machine learning-aided clustering revealed that CD4-CD8- T cells were phenotypically different from CD4+ and CD8+ T cells. Additionally, divergence between maternal decidual and fetal placental compartment was prominent, with absence of DCs from the placenta, but not decidua or embryo. These results provide a novel framework and a syngeneic baseline on which the specific role of alloantigen/tolerance, polymicrobial environment, and models of pregnancy pathology can be precisely modeled and analyzed.

17β-Estradiol induces proliferation of endometrial NK cells (CD56+) in postmenopausal women

OBJECTIVE

The aim of this report was to evaluate the impact of hormone replacement therapy (HRT) on lymphocytic infiltration of the endometrium in postmenopausal women.

METHOD

This study included 58 Japanese patients who had undergone hysterectomy at the University Hospital of Occupational and Environmental Health, Japan. Before surgery, nine patients had received 17β-estradiol (E2), 0.72 mg transdermally for 2-8 weeks (E2 group); 16 patients had received an Estra-1,3,5(10)-triene-3,16α, 17β-triol (E3) vaginal tablet 0.5 mg per month five times (E3 group); and 19 patients had received 17β-estradiol, 0.62 mg, and norethindrone acetate (P), 2.70 mg for 3-16 weeks (E2 + P group). Fourteen patients received no HRT (control group). We examined uterine tissue specimens immunohistochemically for CD45+, CD3+, CD4+, CD8+, CD20+, CD56+, and Ki67 antigen-positive cells.

RESULTS

The numbers of CD56 + cells were significantly increased in the E2 group compared with all other groups (E2 vs. E3: 7.0 vs. 0.75, p = 0.017; E2 vs. E2 + P: 7.0 vs. 0.58, p = 0.009; E2 vs.

CONTROL

7.0 vs. 0.43, p = 0.010). The numbers of CD3+ cells were significantly increased in the E2 group compared with the control group (149.3 vs. 42.6, p = 0.008).

CONCLUSION

17β-Estradiol induced the proliferation of endometrial uterine natural killer cells (CD56+) in postmenopausal women.

High Levels of CXCL8 and Low Levels of CXCL9 and CXCL10 in Women with Maternal RhD Alloimmunization

Maternal RhD alloimmunization is an inflammatory response against protein antigens in fetal red blood cells (RBC). However, not all women become alloimmunized when exposed to RhD⁺ fetal RBC. Thus, this study aimed to evaluate levels of inflammatory chemokines in RhD⁻ pregnant women with erythrocyte alloimmunization. CXCL8, CXCL9, CCL5, and CXCL10 levels were determined from cell culture supernatants by flow cytometry in 46 (30 non-alloimmunized RhD⁻ and 16 previously alloimmunized RhD⁻) pregnant women. CXCL8 levels were significantly higher (P < 0.004), and CXCL9 (P < 0.008) and CXCL10 (P < 0.003) levels were significantly lower in alloimmunized pregnant women. No significant difference in CCL5 levels was detected between the groups. Fetal RHD genotyping was performed in the alloimmunized RhD⁻ group by real-time PCR. Anti-D alloantibody was detected in 10 mothers and anti-D and -C in six mothers. Twelve fetuses were RHD positive and four were RHD negative. Further studies of serum chemokines and placenta tissue could provide a better understanding of the cells involved in the pathogenesis of maternal erythrocyte alloimmunization.

Immunogenetic contributions to recurrent pregnancy loss

While sporadic pregnancy loss is common, occurring in 15 % of pregnancies, recurrent pregnancy loss (RPL) impacts approximately 5 % of couples. Though multiple causes are known (including structural, hormonal, infectious, autoimmune, and thrombophilic causes), after evaluation, roughly half of all cases remain unexplained. The idiopathic RPL cases pose a challenging therapeutic dilemma in addition to incurring much physical and emotional morbidity. Immunogenetic causes have been postulated to contribute to these cases of RPL. Natural Killer cell, T cell expression pattern changes in the endometrium have both been shown in patients with RPL. Human leukocyte antigen (HLA) and cytokine allelic variations have also been studied as etiologies for RPL. Some of the results have been promising, however the studies are small and have not yet put forth outcomes that would change our current diagnosis and management of RPL. Larger database studies are needed with stricter control criteria before reasonable conclusions can be drawn.

Human Decidual Stromal Cells as a Component of the Implantation Niche and a Modulator of Maternal Immunity

The human decidua is a specialized tissue characterized by embryo-receptive properties. It is formed during the secretory phase of menstrual cycle from uterine mucosa termed endometrium. The decidua is composed of glands, immune cells, blood and lymph vessels, and decidual stromal cells (DSCs). In the process of decidualization, which is controlled by oestrogen and progesterone, DSCs acquire specific functions related to recognition, selection, and acceptance of the allogeneic embryo, as well as to development of maternal immune tolerance. In this review we discuss the relationship between the decidualization of DSCs and pathological obstetrical and gynaecological conditions. Moreover, the critical influence of DSCs on local immune cells populations as well as their relationship to the onset and maintenance of immune tolerance is described.

Does pregnancy after a diagnosis of melanoma affect prognosis? Systematic review and meta-analysis

BACKGROUND

Whether pregnancy after diagnosis of melanoma affects a woman's prognosis is unknown. The authors conducted a systematic review and meta-analysis to answer this question.

OBJECTIVE

To evaluate the effect of a subsequent pregnancy on cause-specific death and recurrence of melanomas.

MATERIALS AND METHODS

Five databases (Cochrane Database, MEDLINE, EMBASE, CINAHL, and PubMed) were searched for studies assessing the effect of subsequent pregnancy on risk of melanoma death or recurrence. The authors collated all longitudinal studies of women of childbearing age diagnosed with incident melanoma that compared melanoma outcomes among those who became pregnant after the diagnosis and those who did not. Individual study effect estimates were pooled when available using the weighted average method, and other findings were summarized narratively.

RESULTS

Of 304 citations identified, 5 studies met the inclusion criteria. All 5 assessed melanoma death, and 2 of the 5 assessed recurrence. There was no significant effect of subsequent pregnancy on melanoma mortality after 11 to 20 years of follow-up (pooled hazard ratio, 0.81; 95% confidence interval, 0.60-1.09) and no significant differences in melanoma recurrence. Only one study included patients with all stages of melanoma beyond Stage 1.

CONCLUSION

Current evidence does not support the hypothesis that pregnancy subsequent to successful treatment of melanoma worsens prognosis. However, relevant data are sparse, suggesting that a precautionary approach is warranted regarding childbearing advice to melanoma survivors.

Chemokine CCL24 promotes the growth and invasiveness of trophoblasts through ERK1/2 and PI3K signaling pathways in human early pregnancy

Chemokine CCL24, acting through receptor CCR3, is a potent chemoattractant for eosinophil in allergic diseases and parasitic infections. We recently reported that CCL24 and CCR3 are co-expressed by trophoblasts in human early pregnant uterus. Here we prove with evidence that steroid hormones estradiol (E), progesterone (P), and human chorionic gonadotropin (hCG), as well as decidual stromal cells (DSCs) could regulate the expression of CCL24 and CCR3 of trophoblasts. We further investigate how trophoblast-derived CCL24 mediates the function of trophoblasts in vitro, and conclude that CCL24/CCR3 promotes the proliferation, viability and invasiveness of trophoblasts. In addition, analysis of the downstream signaling pathways of CCL24/CCR3 show that extracellular signal-regulated kinases (ERK1/2) and phosphoinositide 3-kinase (PI3K) pathways may contribute to the proliferation, viability and invasiveness of trophoblasts by activating intracellular molecules Ki67 and matrix metallopeptidase 9 (MMP9). However, we did not observe any inhibitory effect on trophoblasts when blocking c-Jun N-terminal kinase (JNK) or p38 pathways. In conclusion, our data suggests that trophoblast-derived CCL24 at the maternal-fetal interface promotes trophoblasts cell growth and invasiveness by ERK1/2 and PI3K pathways. Meanwhile, pregnancy-related hormones (P and hCG), as well as DSCs could up-regulate CCL24/CCR3 expression in trophoblasts, which may indirectly influence the biological functions of trophoblasts. Thus, our results provide a possible explanation for the growth and invasion of trophoblasts in human embryo implantation.

The production of alpha/beta and gamma/delta double negative (DN) T-cells and their role in the maintenance of pregnancy

The ability of the thymus gland to convert bone marrow-derived progenitor cells into single positive (SP) T-cells is well known. In this review we present evidence that the thymus, in addition to producing SP T-cells, also has a pathway for the production of double negative (DN) T-cells. The existence of this pathway was noted during our examination of relevant literature to determine the cause of sex steroid-induced thymocyte loss. In conducting this search our objective was to answer the question of whether thymocyte loss is the end product of a typical interaction between the reproductive and immune systems, or evidence that the two systems are incompatible. We can now report that "thymocyte loss" is a normal process that occurs during the production of DN T-cells. The DN T-cell pathway is unique in that it is mediated by thymic mast cells, and becomes functional following puberty. Sex steroids initiate the development of the pathway by binding to an estrogen receptor alpha located in the outer membrane of the mast cells, causing their activation. This results in their uptake of extracellular calcium, and the production and subsequent release of histamine and serotonin. Lymphatic vessels, located in the subcapsular region of the thymus, respond to the two vasodilators by undergoing a substantial and preferential uptake of gamma/delta and alpha/beta DN T- cells. These T- cells exit the thymus via efferent lymphatic vessels and enter the lymphatic system.The DN pathway is responsible for the production of three subsets of gamma/delta DN T-cells and one subset of alpha/beta DN T-cells. In postpubertal animals approximately 35 % of total thymocytes exit the thymus as DN T-cells, regardless of sex. In pregnant females, their levels undergo a dramatic increase. Gamma/delta DN T-cells produce cytokines that are essential for the maintenance of pregnancy.

The expression of aminoacyl-tRNA-synthetase-interacting multifunctional protein-1 (Aimp1) is regulated by estrogen in the mouse uterus

Aimp1 is known as a multifunctional cytokine in various cellular events. Recent study showed Aimp1 is localized in glandular epithelial, endothelial, and stromal cells in functionalis and basalis layers of the endometrium. However, the regulatory mechanism of Aimp1 in the uterus remains unknown. In the present study, we found that Aimp1 is expressed in the mouse uterus. Aimp1 transcripts were decreased at diestrus stage. However, the level of Aimp1 protein was significantly increased in the luminal epithelium in the uterine endometrium at estrus stage during the estrous cycle. We found that treatment of estrogen increased the expression of Aimp1 in the uterus in ovarectomized mice. We identified one estrogen receptor binding element (ERE) on mouse Aimp1 promoter. The activity of Aimp1 promoter was increased with estrogen treatment. Our findings indicate that Aimp1 might act as an important regulator to remodel the uterine endometrium and its expression might be regulated by estrogen during the estrous cycle. This will give us better understanding of the dynamic change of uterine remodeling during the estrous cycle.

Differential migration and activation profile of monocytes after trophoblast interaction

Macrophages at the maternal-placental interface coordinate opposite demands under the control of trophoblast cells such as the response against pathogens on one hand, and apoptotic cell clearance and wound healing with the production of suppressor cytokines. Here, we investigated whether trophoblast cells induce maternal monocyte activation towards an alternative activated macrophage profile and whether bacterial or viral stimuli modulate their migratory properties. We used an in vitro model of the maternal-placental interface represented by co-cultures of CD14+ cells isolated from fertile women with first trimester trophoblast cell line (Swan-71 cells) in the presence or absence of pathogen associated molecular pattern (PAMP) stimuli lipopolysaccharide (LPS), peptidoglycan (PGN) or poly [I:C]). Maternal CD14+ cells showed increased CD16 and CD39 expression, both markers associated to an alternative activation profile, with no changes in CD80 expression after trophoblast cell interaction. These changes were accompanied by increased IL-10 and decreased IL-12 production by CD14+ cells. After stimulation with LPS, PGN or poly [I:C], monocytes co-cultured with trophoblast cells had lower production of TNF-α and IL-1β compared with non co-cultured monocytes. Interestingly, monocyte migration towards trophoblast cells was prevented in the presence of LPS or PGN but not after 24h of stimulation with poly [I:C]. LPS or PGN also decreased CCR5, CXCL-8 and CCL5 expression. Finally, trophoblast cells co-cultured with monocytes in the presence of pathological stimuli failed to increase chemokine expression, indicating a bidirectional effect. In conclusion, trophoblast might 'instruct' maternal monocytes to express an alternative activation profile and restrain their early recruitment under pathological threats as one of the first strategies to avoid potential tissue damage at the maternal-placental interface.

Immunomodulatory effects of sex hormones: requirements for pregnancy and relevance in melanoma

Similarities between the pathologic progression of cancer and the physiologic process of placentation (eg, proliferation, invasion, and local/systemic tolerance) have been recognized for many years. Sex hormones such as human chorionic gonadotropin, estrogens, progesterone, and others contribute to induction of immunologic tolerance at the beginning of gestation. Sex hormones have been shown to play contributory roles in the growth of cancers such as breast cancer, prostrate cancer, endometrial cancer, and ovarian cancer, but their involvement as putative mediators of the immunologic escape of cancer is still being elucidated. Herein, we compare the emerging mechanism by which sex hormones modulate systemic immunity in pregnancy and their potentially similar role in cancer. To do this, we conducted a PubMed search using combinations of the following keywords: "immune regulation," "sex hormones," "pregnancy," "melanoma," and "cancer." We did not limit our search to specific publication dates. Mimicking the maternal immune response to pregnancy, especially in late gestation, might aid in design of better therapies to reconstitute endogenous antitumor immunity and improve survival.

Fractalkine (CX3CL1) and its receptor CX3CR1 may contribute to increased angiogenesis in diabetic placenta

Chemokine CX3CL1 is unique, possessing the ability to act as a dual agent: chemoattractant and adhesive compound. Acting via its sole receptor CX3CR1, CX3CL1 participates in many processes in human placental tissue, including inflammation and angiogenesis. Strongly upregulated by hypoxia and/or inflammation-induced inflammatory cytokines secretion, CX3CL1 may act locally as a key angiogenic factor. Both clinical observations and histopathological studies of the diabetic placenta have confirmed an increased incidence of hypoxia and inflammatory reactions with defective angiogenesis. In this study we examined comparatively (diabetes class C complicated versus normal pregnancy) the correlation between CX3CL1 content in placental tissue, the mean CX3CR1 expression, and density of the network of placental microvessels. A sandwich enzyme immunoassay was applied for CX3CL1 measurement in placental tissue homogenates, whereas quantitative immunohistochemical techniques were used for the assessment of CX3CR1 expression and the microvascular density. Significant differences have been observed for all analyzed parameters between the groups. The mean concentration of CX3CL1 in diabetes was increased and accompanied by augmented placental microvessel density as well as a higher expression of CX3CR1. In conclusion, we suggest involvement of CX3CL1/CX3CR1 signaling pathway in the pathomechanism of placental microvasculature remodeling in diabetes class C.