REVIEW ARTICLE: Tolerance Mechanisms in Pregnancy: A Reappraisal of the Role of Class I Paternal MHC Antigens*

Immune rebalancing at the maternal-fetal interface of maternal SARS-CoV-2 infection during early pregnancy

The current coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2) remains a threat to pregnant women. However, the impact of early pregnancy SARS-CoV-2 infection on the maternal-fetal interface remains poorly understood. Here, we present a comprehensive analysis of single-cell transcriptomics and metabolomics in placental samples infected with SARS-CoV-2 during early pregnancy. Compared to control placentas, SARS-CoV-2 infection elicited immune responses at the maternal-fetal interface and induced metabolic alterations in amino acid and phospholipid profiles during the initial weeks post-infection. However, subsequent immune cell activation and heightened immune tolerance in trophoblast cells established a novel dynamic equilibrium that mitigated the impact on the maternal-fetal interface. Notably, the immune response and metabolic alterations at the maternal-fetal interface exhibited a gradual decline during the second trimester. Our study underscores the adaptive immune tolerance mechanisms and establishment of immunological balance during the first two trimesters following maternal SARS-CoV-2 infection.

Identification of New Markers of Angiogenic Sprouting Using Transcriptomics: New Role for RND3

BACKGROUND

New blood vessel formation requires endothelial cells to transition from a quiescent to an invasive phenotype. Transcriptional changes are vital for this switch, but a comprehensive genome-wide approach focused exclusively on endothelial cell sprout initiation has not been reported.

METHODS

Using a model of human endothelial cell sprout initiation, we developed a protocol to physically separate cells that initiate the process of new blood vessel formation (invading cells) from noninvading cells. We used this model to perform multiple transcriptomics analyses from independent donors to monitor endothelial gene expression changes.

RESULTS

Single-cell population analyses, single-cell cluster analyses, and bulk RNA sequencing revealed common transcriptomic changes associated with invading cells. We also found that collagenase digestion used to isolate single cells upregulated the Fos proto-oncogene transcription factor. Exclusion of Fos proto-oncogene expressing cells revealed a gene signature consistent with activation of signal transduction, morphogenesis, and immune responses. Many of the genes were previously shown to regulate angiogenesis and included multiple tip cell markers. Upregulation of SNAI1 (snail family transcriptional repressor 1), PTGS2 (prostaglandin synthase 2), and JUNB (JunB proto-oncogene) protein expression was confirmed in invading cells, and silencing JunB and SNAI1 significantly reduced invasion responses. Separate studies investigated rounding 3, also known as RhoE, which has not yet been implicated in angiogenesis. Silencing rounding 3 reduced endothelial invasion distance as well as filopodia length, fitting with a pathfinding role for rounding 3 via regulation of filopodial extensions. Analysis of in vivo retinal angiogenesis in Rnd3 heterozygous mice confirmed a decrease in filopodial length compared with wild-type littermates.

CONCLUSIONS

Validation of multiple genes, including rounding 3, revealed a functional role for this gene signature early in the angiogenic process. This study expands the list of genes associated with the acquisition of a tip cell phenotype during endothelial cell sprout initiation.

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

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

The therapeutic effects and optimal timing of granulocyte colony stimulating factor intrauterine administration during IVF-ET

Most of embryos fail to produce live offspring during In Vitro Fertilization-Embryo Transfer (IVF-ET) procedure. There is a dearth of research activity addressing this problem despite the significant population of women suffering from repeated implantation failure after transfer of high-quality of embryos. As a clinically accessible option, granulocyte colony stimulating factor (G-CSF) is often used for the treatment to improve the rates of embryo implantation. However, there are currently no evidence-based standardized protocol for the clinical use of G-CSF. G-CSF was administered into one side of mouse uterine horns and saline was infused into the other side of horns as a control. Intrauterine G-CSF administration showed maximal effects 24 h after administration in enhancing endometrial receptivity and subsequent increase of angiogenesis by demonstrating elevated integrin β3 and OPN and reduced cytotoxicity of NK cells. Furthermore, G-CSF administration 24 h prior to embryo transfer promoted the stability of attached embryos at the early stage of implantation in vitro. Our findings suggest as new consensus criteria providing a potential therapeutic strategy of the clinical use of G-CSF to achieve maximal effects of IVF-ET for patients who are suffering from repeated implantation failure with the problems with endometrial receptivity.

Polarization disorder of decidual NK cells in unexplained recurrent spontaneous abortion revealed by single-cell transcriptome analysis

BACKGROUND

Unexplained recurrent spontaneous abortion (URSA) is one of the most common diseases in pregnancy and is mainly caused by immune disorders. The foetus is similar to semiallogeneic maternal tissue, so the balance of immune tolerance must be dynamically maintained during pregnancy. Decidual natural killer (dNK) cells primarily mediate the immune tolerance microenvironment at the maternal-fetal interface. By using single-cell RNA sequencing (scRNA-seq) and high-throughput transcriptome sequencing analysis, we explored the characteristic distribution of dNK cells in URSA patients.

METHODS

Control maternal-fetal interface tissue (from normal pregnant women, n = 3) and case maternal-fetal interface tissue (from patients with URSA, n = 3) samples were analysed by scRNA-seq and high-throughput transcriptome sequencing.

RESULTS

By scRNA-seq, we demonstrated the maturation process of the transition of dNK cells from cytotoxic characteristics to immune tolerance in transcriptome analysis. Moreover, compared with normal pregnant women, serious disturbances in the polarization process of dNK cells were found in URSA. Simultaneously, the transcriptional level of the extracellular matrix (ECM) in URSA patients showed a significant decrease. The dNK cells interacted with extravillous trophoblasts to achieve immune-tolerant polarization.

CONCLUSIONS

Insufficient expression of KIRs during dNK cell differentiation might be a key reason why polarized dNK cells still had high cytotoxic reactivity in URSA patients. Abnormal expression of ECM may affect the interaction of dNK cells with EVTs, making dNK cells immature. Both resulted in maternal immune intolerance to the foetus during pregnancy.

Killer-cell immunoglobulin-like receptor/human leukocyte antigen-C combination and 'great obstetrical syndromes' (Review)

Recurrent pregnancy loss (RPL), pre-eclampsia (PE), fetal growth restriction (FGR), and preterm delivery are examples of 'great obstetrical syndromes' (GOS). Placental dysfunction is the most common pathogenesis of GOS. In human pregnancies, the effects of uterine natural killer cells involve angiogenesis, promoting the remodeling of uterine spiral artery, and improving the invasion of trophoblast cells. The uNK cells supply killer immunoglobulin-like receptors (KIRs), which come into contact with human leukocyte antigen-C (HLA-C) ligands expressed by extravillous trophoblast cells (EVTs). Numerous studies have investigated the association between GOS and KIR/HLA-C combination. However, the outcomes have not been conclusive. The present review aimed to reveal the association between GOS and KIR/HLA-C combination to screen out high-risk pregnancies, strengthen the treatment of pregnancy complications, and reduce the frequency of adverse maternal and fetal outcomes. It has been reported that a female with a KIR AA genotype and a neonate with a paternal HLA-C2 molecule is more prone to develop GOS and have a small fetus since less cytokines were secreted by uNK cells. Conversely, the combination of KIR BB haplotype (including the activating KIR2DS1) and HLA-C2 can induce the production of cytokines and increase trophoblast invasion, leading to the birth of a large fetus. KIR/HLA-C combinations may be applicable in selecting third-party gametes or surrogates. Detection of maternal KIR genes and HLA-C molecules from the couple could serve as useful markers for predicting and diagnosing GOS.

Regulatory T Cells Beyond Autoimmunity: From Pregnancy to Cancer and Cardiovascular Disease

The evolution of the full range of functions of regulatory T cells (Treg) coincides with the evolution of mammalian pregnancy. Accordingly, Treg function has been shown to be crucial for maternal-fetal tolerance and implantation. As reproduction is a key point of selective pressure, mammalian pregnancy may represent an evolutionary driver for the development of Treg. Yet beyond the chronological boundaries of mammalian pregnancy, several key physiological and pathological events are being gradually uncovered as involving the immunomodulating functions of Treg cells. These include autoimmunity, age-related inflammation in males and in post-menopausal females, but also oncological and cardiovascular diseases. The latter two sets of diseases collectively compose the main causes of mortality world-wide. Emerging data point to Treg-modulable effects in these diseases, in a departure from the relatively narrower perceived role of Treg as master regulators of autoimmunity. Yet recent evidence also suggests that changes in intestinal microbiota can affect the above pathological conditions. This is likely due to the finding that, whilst the presence and maintenance of intestinal microbiota requires active immune tolerance, mediated by Treg, the existence of microbiota per se profoundly affects the polarization, stability, and balance of pro- and anti-inflammatory T cell populations, including Treg and induced Treg cells. The study of these “novel,” but possibly highly relevant from an ontogenesis perspective, facets of Treg function may hold great potential for our understanding of the mechanisms underlying human disease.

Neuromyelitis optica spectrum disorders and pregnancy: therapeutic considerations

Neuromyelitis optica spectrum disorders (NMOSD) are a type of neurological autoimmune disease characterized by attacks of CNS inflammation that are often severe and predominantly affect the spinal cord and optic nerve. The majority of individuals with NMOSD are women, many of whom are of childbearing age. Although NMOSD are rare, several small retrospective studies and case reports have indicated that pregnancy can worsen disease activity and might contribute to disease onset. NMOSD disease activity seems to negatively affect pregnancy outcomes. Moreover, some of the current NMOSD treatments are known to pose risks to the developing fetus and only limited safety data are available for others. Here, we review published studies regarding the relationship between pregnancy outcomes and NMOSD disease activity. We also assess the risks associated with using disease-modifying therapies for NMOSD during the course of pregnancy and breastfeeding. On the basis of the available evidence, we offer recommendations regarding the use of these therapies in the course of pregnancy planning in individuals with NMOSD.

Cooperative inflammation: The recruitment of inflammatory signaling in marsupial and eutherian pregnancy

The evolution of viviparity in therian mammals, i.e. marsupials and "placental" mammals, occurred by retention of the conceptus in the female reproductive tract and precocious "hatching" from the shell coat. Both eutherian embryo implantation and the opossum embryo attachment reaction are evolutionarily derived from and homologous to a defensive inflammatory process induced after shell coat hatching. However, both lineages, marsupials and placental mammals, have modified the inflammatory response substantially. We review the induction, maintenance, and effects of inflammation throughout pregnancy, with special attention to the role of prostaglandins and the mucosal inflammatory response, both of which likely had roles in early mammalian viviparity. We propose that the key step was not only suppression of the inflammatory response after implantation in placental mammals, but also the transfer of the inflammatory cell-cell communication network to a different set of cell types than in generic inflammation. To support this conclusion we discuss evidence that pro-inflammatory signal production in the opossum is not limited to maternal cells, as expected in bona fide defensive inflammation, but also includes fetal tissues, in a process we term cooperative inflammation. The ways in which the inflammatory reaction was independently modified in these two lineages helps explain major life history differences between extant marsupials and eutherians.

Immunomodulatory effects of Salvianolic acid B in a spontaneous abortion mouse model

Pregnancy is a kind of natural immune tolerance. Immune factors play an important role in recurrent spontaneous abortion and repeated implantation failure. Salvianolic acid B (SalB) has anti-tumor, anti-inflammatory, anti-oxidation and immunomodulatory functions. However, there are few reports on the relationship between SalB and maternal-fetal immune tolerance. In this study, CBA/J × DBA/2 J mice as a spontaneous abortion mouse model were given SalB. The results showed that the abortion rate was significantly decreased after SalB treatment. The populations of Nkp46 and cytotoxic CD8⁺ T cells in the placenta of female mice treated with SalB were significantly decreased. The qRT-PCR showed that SalB was able to significantly reduce the expression of pro-inflammatory factors and Toll-like Receptor in the placenta. In addition, SalB was able to increase the area of the labyrinth in the placenta. In conclusion, these findings suggest that SalB is beneficial for the immune-modulation at the maternal-fetal interface in a spontaneous abortion mouse model, resulting in a decrease in the abortion rate. This may encourage new ideas for the treatment of patients with repeated implantation failure.

Reduced CD200 expression is associated with altered Th1/Th2 cytokine production in placental trophoblasts from preeclampsia

PROBLEM

To determine if altered trophoblast CD200 and CD200R expressions promote inflammatory cytokine production in preeclamptic placentas.

METHODS OF STUDY

Placental tissue CD200 and CD200R expressions were determined by immunostaining. Tissue sections from first-, second-, and third-trimester, normal term, and preeclamptic placentas were used. CD200 and CD200R expressions and cytokine production of TNFα, sTNFR1, INFγ, IL-4, IL-6, IL-8, and IL-10 were determined in trophoblasts from normal and preeclamptic placentas and in normal trophoblasts transfected with CD200 siRNA.

RESULTS

CD200, but not CD200R, expression was significantly reduced in trophoblasts from preeclamptic compared to normal placentas. Trophoblast from preeclamptic placentas and trophoblast transfected with CD200 siRNA produced significantly more TNFα, sTNFR1, IL-6, and IL-8, but significantly less IL-10, than trophoblasts from normal control placentas.

CONCLUSION

Downregulation of CD200 expression resulted in an imbalance of increased Th1 cytokine and decreased Th2 cytokine production in placental trophoblasts in preeclampsia.

Differences of glycocalyx composition in the structural elements of placenta in preeclampsia

INTRODUCTION

Glycans expressed in the fetal-maternal interface were shown to exert immunomodulating effects and to mediate interactions between the cells. The aim of this study was to investigate alterations in the structure of carbohydrate chains of glycocalyx in placental tissue in pregnancies complicated with preeclampsia (PE).

METHODS

A histochemical analysis of placental tissues was performed with a panel of biotinylated lectins. We analyzed placental tissues in women who had severe or moderate PE and compared them to placentas from women with normal pregnancies.

RESULTS

There was decreased content of terminal residues of α(2,6)-linked sialic acid (as stained by SNA lectin) in the carbohydrate chains of glycocalyx of the endothelium of placental terminal villi in patients with moderate preeclampsia. The composition of the glycocalyx of syncytiotrophoblast in patients of this group did not differ from the control group. Amount of the glycans with terminal β-Gal- (ECL) and α-mannosyl residues (ConA) in the syncytiotrophoblast and capillary endothelium of the placenta was significantly higher in the group with severe PE compared to the control group. The increased content of sialoglycans with α(2,6)-linked sialic acids residues were discovered in the syncytium, and the decreased content of α(2,3)-linked sialic acids residues - in the endothelium of terminal villi in preeclampsia.

DISCUSSION

The most prominent alteration of the glycocalyx composition was found in the placentas of women with severe preeclampsia. It is likely that the modified glycome of syncytiotrophoblast and capillary endothelium may play an important role in pathogenesis of preeclampsia.

Histocompatibility: clarifying fusion confusion

In the colonial tunicate Botryllus schlosseri, a co-dominant trait determines the capacity of adjacent colonies to fuse or reject. An innovative RNA sequencing approach has now identified the gene that predicts the outcomes of this naturally occurring allograft.

Association between IL-6 -174 G/C, IL-6 -634 G/C, and IFN-γ +874 A/T polymorphisms and susceptibility to recurrent pregnancy loss: a meta-analysis

OBJECTIVE

The aim of this study was to determine whether interleukin-6 (IL-6) -174 G/C, IL-6 -634 G/C, and interferon-γ (IFN-γ) +874 A/T polymorphisms are associated with susceptibility to recurrent pregnancy loss (RPL).

METHODS

We conducted a literature search using PubMed and EMBASE databases and performed a meta-analysis using fixed- or random-effects models.

RESULTS

A total of 15 articles met the study inclusion criteria. When all study subjects were considered together, meta-analysis showed no association between RPL and the IL-6 -174 GG + GC genotype (odds ratio [OR] = 0.794, 95 % confidence interval [CI] = 0.542-1.163, p = 0.236). However, stratification of the data by ethnicity indicated an association between this genotype and RPL in non-Caucasians (OR = 0.528, 95 % CI = 0.302-0.925, p = 0.028), but not in Caucasian populations. Moreover, meta-analysis revealed an association between RPL and the IL-6 -634 GG + GC genotype in all study subjects (OR = 0.556, 95 % CI = 0.383-0.806, p = 0.002), while stratification by ethnicity revealed a negative association between this genotype and RPL in Asian (OR = 0.545, 95 % CI = 0.371-0.800, p = 0.002) but not Middle Eastern populations. Furthermore, a relationship between the IFN-γ +874 A allele and RPL was identified in non-Caucasians (OR = 1.403, 95 % CI = 1.133-1.734, p = 0.002), but not in Caucasians.

CONCLUSIONS

This meta-analysis demonstrates that IL-6 -174 G/C, IL-6 -634 G/C, and IFN-γ +874 A/T polymorphisms are associated with susceptibility to RPL, particularly in non-Caucasians.

Reduced CD200 and CD200R1 expression in human chorionic villi contributes to early spontaneous abortion

OBJECTIVE

To examine the expression of CD200 and its receptor (CD200R) in human chorionic villi during the first trimester of normal pregnancy and early spontaneous abortion (ESA).

DESIGN

Prospective study.

METHODS

Expression of CD200 and CD200R in the chorionic villi was determined using streptavidin-peroxidase immunohistochemistry, confocal laser scanning microscopy and real-time polymerase chain reaction.

POPULATION

Thirty-five women diagnosed with ESA and 30 women experiencing a healthy pregnancy in a medical university hospital in China were enrolled in this study between 2011 and 2013.

MAIN OUTCOME MEASURES

CD200 and CD200R expression.

RESULTS

The expression of CD200 in syncytiotrophoblast cells was significantly higher during normal pregnancy than in ESA (0.51 ± 0.05 vs. 0.35 ± 0.05). In contrast, expression of CD200 in cytotrophoblast cells and CD200R in stromal cells was significantly lower during normal pregnancy when compared with ESA (CD200: 0.16 ± 0.02 vs. 0.32 ± 0.03; CD200R: 0.19 ± 0.03 vs. 0.22 ± 0.02). In villi, the expression of both CD200 protein and CD200R transcripts were significantly higher in healthy first-trimester pregnancy than in ESA (CD200: 156.89 ± 105.65 vs. 37.51 ± 17.62).

CONCLUSIONS

There is an increase in inhibitory properties of human chorionic villi during normal pregnancy. The mechanism underlying ESA might be associated with enhanced expression of CD200 and CD200R in the trophoblast, leading to an upregulation of the immune response during the first trimester of pregnancy.

Evidence for a role for the adaptive immune response in human term parturition

PROBLEM

Spontaneous labor at term involves leukocyte recruitment and infiltration into the choriodecidua; yet, characterization of these leukocytes and their immunological mediators is incomplete. The purpose of this study was to characterize the immunophenotype of choriodecidual leukocytes as well as the expression of inflammatory mediators in human spontaneous parturition at term.

METHOD OF STUDY

Choriodecidual leukocytes were analyzed by FACS, immunohistochemistry, and RT-PCR in three different groups: (i) preterm gestation delivered for medical indications without labor; (ii) term pregnancy without labor; and (iii) term pregnancy after spontaneous labor.

RESULTS

Two T-cell subsets of memory-like T cells (CD3(+) CD4(+) CD45RO(+) and CD3(+) CD4(-) CD8(-) CD45RO(+) cells) were identified in the choriodecidua of women who had spontaneous labor. Evidence for an extensive immune signaling network composed of chemokines (CXCL8 and CXCL10), chemokine receptors (CXCR1-3), cytokines (IL-1β and TNF-α), cell adhesion molecules, and MMP-9 was identified in these cells during spontaneous labor at term.

CONCLUSIONS

The influx of memory-like T cells in the choriodecidua and the evidence that they are active by producing chemokines and cytokines, and expressing chemokine receptors, cell adhesion molecules, and a matrix-degrading enzyme provides support for the participation of the adaptive immune system in the mechanisms of spontaneous parturition at term.

Influenza in pregnancy

Please cite this paper as: Memoli et al. (2012) Influenza in pregnancy. Influenza and Other Respiratory Viruses 00(00), 000–000.

The 2009 pandemic served as a strong reminder that influenza‐induced disease can have a great impact on certain at‐risk populations and that pregnant women are one such important population. The increased risk of fatal and severe disease in these women was appreciated more than 500 years ago, and during the last century, pregnant women and their newborns have continued to be greatly affected by both seasonal and pandemic influenza. In this review, we briefly discuss the data collected both before and after the 2009 pandemic as it relates to the impact of influenza on pregnant women and their fetuses/newborns, as well as risk variables, clinical features, clues to pathophysiologic mechanisms, and approaches to treatment and prevention.

Characterization and functionality of the CD200-CD200R system during mesenchymal stromal cell interactions with T-lymphocytes

Mesenchymal stromal cells (MSCs) possess a specific immunological profile that makes them potentially useful for immune-based therapies. Adipose tissue (AT) and Wharton's jelly (WJ) are considered to be valuable alternatives to bone marrow (BM) as sources of MSCs. These MSCs exhibit strong immunomodulatory properties that affect lymphocyte responses. The CD200/CD200R axis has been reported to be important in regulating the immune responses. Engagement of CD200R by CD200 initiates an inhibitory pathway that displays immunosuppressive effects. Because the CD200/CD200R axis is involved in immunoregulation, we investigated the expression and role of this ligand/receptor pair in MSCs and T-lymphocytes during co-culture. CD200 is differently expressed and modulated on MSCs depending on the tissue of origin and the culture conditions. Among the different MSC sources, WJ-MSCs express CD200 in the greatest proportion. This high constitutive CD200 expression may represent a distinctive marker for WJ-MSCs. A pro-inflammatory environment and IFN-γ in particular induce an increase in CD200 expression by BM-MSCs. In T-lymphocytes, CD200R and CD200 are differently distributed between the CD4(+) and CD8(+) T-cell subsets. During co-culture, blocking CD200-CD200R interactions does not prevent MSC-mediated inhibition of lymphocyte proliferation. However, depending on their origin, MSCs are able to modulate the expression of both CD200 and CD200R on some T-cells. Further study is required to understand the function of CD200 expression by nonmyeloid cells such MSCs and the significance of CD200 and C200R expression by T-cells. The findings presented here support bidirectional communication between MSCs and T-lymphocytes. Understanding the role of this ligand-receptor pair during co-culture will improve and increase the clinical use of MSCs.

Evaluation of KIR genes in recurrent miscarriage

PURPOSE

Natural killer (NK) cells express killer immunoglobulin-like receptors (KIRs) which recognize HLA class I molecules on trophoblasts. KIRs could either activate NK cells or inhibit them to produce soluble factors necessary for the maintenance of pregnancy, thus they are suspected of being involved in the causes of recurrent miscarriage. The aim of this study was to evaluate whether there is any possible association between KIR genes, genotypes and recurrent miscarriage.

METHODS

The present study was carried out on 40 women who had unexplained recurrent miscarriage and 90 controls. Sequence-specific oligonucleotide probes analysis were used to investigate 16 KIR genes. All data were statistically analyzed by Fisher Exact Test.

RESULTS

The rate of Bx genotypes that consists elevated number of activating KIR genes was significantly higher (p = 0.014) in women with recurrent miscarriage when compared with the control group. Additionally, the frequency of AA genotype (AA1) of the subjects in the study group was significantly lower than the frequency of the subjects in the control group (p = 0,014). Furthermore, there were no statistically significant differences in the frequencies of the individual KIR genes between women with recurrent miscarriage and the control group.

CONCLUSIONS

Inclined balance of KIRs toward an activating state in NK cells may contribute to recurrent miscarriage.

Characterization of the intronic portion of cadherin superfamily members, common cancer orchestrators

Cadherins are cell-cell adhesion proteins essential for the maintenance of tissue architecture and integrity, and their impairment is often associated with human cancer. Knowledge regarding regulatory mechanisms associated with cadherin misexpression in cancer is scarce. Specific features of the intronic-structure and intronic-based regulatory mechanisms in the cadherin superfamily are unidentified. This study aims at systematically characterizing the intronic portion of cadherin superfamily members and the identification of intronic regions constituting putative targets/triggers of regulation, using a bioinformatic approach and biological data mining. Our study demonstrates that the cadherin superfamily genes harbour specific characteristics in comparison to all non-cadherin genes, both from the genomic and transcriptional standpoints. Cadherin superfamily genes display higher average total intron number and significantly longer introns than other genes and across the entire vertebrate lineage. Moreover, in the human genome, we observed an uncommon high frequency of MIR (mammalian-wide interspersed repeats) and MaLR (mammalian-wide interspersed repeats, a subtype of LTR) regulatory-associated repetitive elements at 5'-located introns, concomitantly with increased de novo intronic transcription. Using this approach, we identified cadherin intronic-specific sites that may constitute novel targets/triggers of cadherin superfamily expression regulation. These findings pinpoint the need to identify mechanisms affecting particularly MIR and MaLR elements located in introns 2 and 3 of human cadherin genes, possibly important in the expression modulation of this superfamily in homeostasis and cancer.

Analysis of RCAS1 immunoreactivity within hydatidiform mole cells and decidual cells according to the applied therapeutic strategy: surgery or surgery followed by chemotherapy

INTRODUCTION

Trophoblast cells cooperate with both maternal immune cells and decidual cells to help develop the suppressive microenvironment of the endometrium. The maternal immune response against hydatidiform mole depends on this suppressive endometrial profile. Since RCAS1 is one of the molecular factors participating in the development of the suppressive profile of the endometrium we decided to examine the immunoreactivity of the RCAS1 within both the trophoblast and decidual cells during the development of hydatidiform mole.

METHODS

We analyzed the immunoreactivity of RCAS1 on both trophoblast and decidual cells derived from patients who underwent curettage because of hydatidiform mole. These patients were then divided into two subgroups according to whether or not they required chemotherapy after the surgical procedure.

RESULT

We observed significantly lower immunoreactivity levels of both RCAS1 within the complete molar lesions of the patients on whom surgery alone was performed when compared to the levels found in those for whom surgery was followed by chemotherapy.

CONCLUSION

RCAS1 staining may provide information regarding the intensity of the immunosuppressive microenvironment of both the molar lesion and the endometrium. This information can prove significant in determining the clinical course of hydatidiform mole.

Role of endometrial immune cells in implantation

Implantation of an embryo occurs during the mid-secretory phase of the menstrual cycle, known as the "implantation window." During this implantation period, there are significant morphologic and functional changes in the endometrium, which is followed by decidualization. Many immune cells, such as dendritic and natural killer (NK) cells, increase in number in this period and early pregnancy. Recent works have revealed that antigen-presenting cells (APCs) and NK cells are involved in vascular remodeling of spiral arteries in the decidua and lack of APCs leads to failure of pregnancy. Paternal and fetal antigens may play a role in the induction of immune tolerance during pregnancy. A balance between effectors (i.e., innate immunity and helper T [Th] 1 and Th17 immunity) and regulators (Th2 cells, regulatory T cells, etc.) is essential for establishment and maintenance of pregnancy. The highly complicated endocrine-immune network works in decidualization of the endometrium and at the fetomaternal interface. We will discuss the role of immune cells in the implantation period and during early pregnancy.

Modulation and recruitment of inducible regulatory T cells by first trimester trophoblast cells

PROBLEM  The specialized regulatory T-cells (Treg) population, essential for maternal tolerance of the fetus, performs its suppressive actions in the critical peri-implantation phase of pregnancy. In the present work, we investigated whether trophoblast cells are able to induce Treg recruitment, differentiation, and whether these mechanisms are modified by a bacterial or viral infection. METHOD OF STUDY  Human T-regulatory cells were differentiated from naïve CD45RA(+) CCR7(+) cells obtained from peripheral blood mononuclear cells cultured with IL-2 and TGFβ over 5 days. Induction of iTregs (CD4(+)  Foxp3(+) cells) was evaluated using low serum conditioned media (LSCM), obtained from two first trimester trophoblast cell lines, Swan-71 and HTR8. Coculture experiments were carried out using transwell assays where trophoblast cells were in the absence or presence of PGN, LPS, or Poly [I:C]. Cytokine production was measured by multiplex analysis. RESULTS  Trophoblast cells constitutively secrete high levels of TGFβ and induced a significant increase of Foxp3 expression accompanied by a specific T-reg cytokine profile. Moreover, trophoblast cells were able to recruit iTregs in a specific manner. CONCLUSION  We demonstrate that trophoblast cells have an active role on the recruitment and differentiation of iTregs, therefore, contributing to the process of immune regulation at the placental-maternal interface.

Phagocytosis, a potential mechanism for myeloid-derived suppressor cell regulation of CD8+ T cell function mediated through programmed cell death-1 and programmed cell death-1 ligand interaction

CD8(+) T cells become exhausted, inducing cell surface protein programmed cell death-1 (PD-1) as chronic virus diseases or tumors progress, but underlying mechanisms of this are unclear. We previously showed that M-CSF is important for developing tolerogenic dendritic cells (DCs) from human CD14(+) monocytes. In this article, we identify M-CSF-derived DCs (M-DCs) after stimulation with IL-10 as myeloid-derived suppressor cells with additional tolerogenic activities to CD8(+) T cells. IL-10 increased PD-1 ligand expression on M-DC, and IL-10-stimulated M-DCs (M-DC/IL-10) induced expression of PD-1 on, and apoptosis of, CD8(+) T cells and phagocytosed CD8(+) T cells. Enhanced phagocytic activity of M-DC/IL-10 required IFN-γ, which further increased PD-1 ligand and PD-2 ligand expression on M-DC/IL-10. IFN-γ-stimulated M-DC/IL-10 cells were phenotypically macrophage-like cells with little or no expression of CD86, a costimulatory molecule, but with high expression levels of CD14, CD200R, and CD80. No phagocytic activity was detected with GM-CSF-derived DCs. We propose that phagocytosis by IFN-γ-stimulated M-DC/IL-10 cells, which may be DCs or, alternatively, a unique subset of macrophages, may be a mechanism by which IFN-γ-producing CD8(+) T cells are tolerized after type 1 immune responses to chronic virus or tumor, and that IFN-γ links effector CD8(+) T cells to their phagocytic clearance.

Neutralization of LPS or blockage of TLR4 signaling prevents stress-triggered fetal loss in murine pregnancy

Maternal stress can cause loss of both histocompatible (syngeneic) and histoincompatible (semiallogeneic) embryos in pregnant mice. Stress increases abortogenic Th1 cytokines and reduces levels of anti-abortogenic Th2 cytokines, progesterone levels, and T regulatory cell activity. While physiological levels of interferon-γ promote vascular remodeling at the feto-maternal interface, an overshooting Th1 cytokine response requires a Toll-like receptor (TLR)-mediated "danger signal" such as lipopolysaccharide (LPS). Interestingly, stress can enhance permeability of mucosal membranes to entry of bacterial products and promote transmucosal migration of commensal bacteria. We hypothesized that bacterial component such as LPS may provide the danger signal through which stress triggers maternal immune activation, subsequently resulting in fetal rejection. Blocking the TLR4 receptor for LPS or neutralization of LPS using bactericidal permeability increasing protein abrogate fetal loss due to sonic stress challenge in DBA/2J-mated CBA/J mice. These treatments prevented stress-triggered immune responses in the decidua, upregulated Treg cells, and reduced the frequency of mature dendritic cells in uterine-draining lymph nodes but not in the uterus. Interestingly, anti-TLR4 treatment only partly ameliorated stress-induced endocrine responses, such as increased hypothalamic corticotropin releasing hormone and vasopressin mRNA expression but not decrease of serum progesterone. Galectin-1 knock-out mice were more susceptible to stress-triggered complete implantation failure rather than fetal loss, which was also abolished by LPS neutralization. Insights provided in this paper shed new light on the mechanisms by which stress affects pregnancy outcome and introduce microbial-derived LPS as a mediator within the cascade of stress-triggered immune and endocrine events during pregnancy.

The pro-inflammatory role of adiponectin at the maternal-fetal interface

PROBLEM

A successful pregnancy is contingent on maternal tolerance of the immunologically foreign fetus. Prevalent diseases such as preeclampsia arise in part due to an inappropriate immune response by the placenta. A number of molecules have been proposed to temper cellular response to pro-inflammatory mediators, including CD24 and Siglec10.

METHODS

Cytotrophoblast cells from healthy term placentas were treated with adiponectin in vitro and analyzed with qPCR and ELISA-based assays. Immunohistochemistry was performed on term villous sections and cultured trophoblasts.

RESULTS

Treatment with adiponectin increased expression of IL-1β and IL-8. Term villi express CD24 in cytotrophoblasts and the syncytiotrophoblast, and Siglec10 by the syncytiotrophoblast. Treatment of trophoblast cells with adiponectin increased Siglec10 expression.

CONCLUSION

These data describe a role for adiponectin in enhancing pro-inflammatory signals in in vitro syncytialized trophoblasts. Additionally, this represents the first time the CD24/Siglec10 pathway has been implicated in a trophoblast response to a pro-inflammatory mediator.