An immunohistochemical study of leucocytes in human endometrium, first and third trimester basal decidua

The central role of natural killer cells in preeclampsia

Preeclampsia (PE) is a disease that is unique to pregnancy and affects multiple systems. It can lead to maternal and perinatal mortality. The precise etiology of PE is unclear. Patients with PE may have systemic or local immune abnormalities. A group of researchers has proposed that the immune communication between the fetus and mother is primarily moderated by natural killer (NK) cells as opposed to T cells, since NK cells are the most abundant immune cells in the uterus. This review examines the immunological roles of NK cells in the pathogenesis of PE. Our aim is to provide obstetricians with a comprehensive and updated research progress report on NK cells in PE patients. It has been reported that decidual NK (dNK) cells contribute to the process of uterine spiral artery remodeling and can modulate trophoblast invasion. Additionally, dNK cells can stimulate fetal growth and regulate delivery. It appears that the count or proportion of circulating NK cells is elevated in patients with or at risk for PE. Changes in the number or function of dNK cells may be the cause of PE. The Th1/Th2 equilibrium in PE has gradually shifted to an NK1/NK2 equilibrium based on cytokine production. An improper combination of killer cell immunoglobulin-like receptor (KIR) and human leukocyte antigen (HLA)-C may lead to insufficient activation of dNK cells, thereby causing PE. In the etiology of PE, NK cells appear to exert a central effect in both peripheral blood and the maternal-fetal interface. To maintain immune equilibrium both locally and systemically, it is necessary to take therapeutic measures directed at NK cells.

Imaging Mass cytometry reveals the prominent role of myeloid cells at the maternal-fetal interface

Although the immunological complexity of the maternal-fetal interface is well appreciated, the actual interaction of maternal immune cells and fetal trophoblasts is insufficiently understood. To comprehend the composition and spatial orientation of maternal immune cells and fetal extravillous trophoblasts, we applied imaging mass cytometry on decidua basalis of the three trimesters of healthy pregnancy. Within all trimesters, we observed considerably higher frequencies of myeloid cells in the decidua than is seen with single-cell suspension techniques. Moreover, they were the most pronounced cell type in the microenvironment of other decidual cells. In first trimester, HLA-DR^- macrophages represented the most abundant myeloid subcluster and these cells were frequently observed in the vicinity of trophoblasts. At term, HLA-DR⁺ macrophage subclusters were abundantly present and frequently observed in the microenvironment of T cells. Taken together, our results highlight the dynamic role of myeloid cells at the human maternal-fetal interface throughout gestation.

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Frequency of myeloid cells is underestimated after tissue digestion

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Myeloid cells could support NK cells with proper trophoblast invasion

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Myeloid cells are dynamic in their role throughout gestation

Activated γδ T Cells With Higher CD107a Expression and Inflammatory Potential During Early Pregnancy in Patients With Recurrent Spontaneous Abortion

Previous studies have reported the involvement of γδ T cells in recurrent spontaneous abortion (RSA); however, both pathogenic and protective effects were suggested. To interrogate the role of γδ T cells in RSA, peripheral blood from RSA patients and healthy women with or without pregnancy were analyzed for γδ T cells by flow cytometry (n = 9–11 for each group). Moreover, the decidua from pregnant RSA patients and healthy controls (RSA-P and HC-P group, respectively) was simultaneously stained for γδ T cells by immunohistochemistry (IHC) and bulk sequenced for gene expression. Our results demonstrated that the frequencies of peripheral γδ T cells and their subpopulations in RSA patients were comparable to that in healthy subjects, but the PD1 expression on Vδ2⁺ cells was increased in pregnant patients. Furthermore, peripheral Vδ2⁺ cells in RSA-P patients demonstrated significantly increased expression of CD107a, as compared to that in pregnant healthy controls. In addition, RSA-P patients had higher proportion of IL-17A-secreting but not IL-4-secreting Vδ2⁺ cells compared to the control groups. In decidua, an inflammatory microenvironment was also evident in RSA-P patients, in which CCL8 expression and the infiltration of certain immune cells were higher than that in the HC-P group, as revealed by transcriptional analysis. Finally, although the presence of γδ T cells in decidua could be detected during pregnancy in both RSA patients and healthy subjects by multicolor IHC analysis, the expression of CD107a on γδ T cells was markedly higher in the RSA-P group. Collectively, our results indicated that the increased activation, cytotoxicity, and inflammatory potential of peripheral and/or local γδ T cells might be responsible for the pathogenesis of RSA. These findings could provide a better understanding of the role of γδ T cells in RSA and shed light on novel treatment strategies by targeting γδ T cells for RSA patients.

Visualizing Dynamic Changes at the Maternal-Fetal Interface Throughout Human Pregnancy by Mass Cytometry

During healthy pregnancy, a balanced microenvironment at the maternal-fetal interface with coordinated interaction between various immune cells is necessary to maintain immunological tolerance. While specific decidual immune cell subsets have been investigated, a system-wide unbiased approach is lacking. Here, mass cytometry was applied for data-driven, in-depth immune profiling of the total leukocyte population isolated from first, second, and third trimester decidua, as well as maternal peripheral blood at time of delivery. The maternal-fetal interface showed a unique composition of immune cells, different from peripheral blood, with significant differences between early and term pregnancy samples. Profiling revealed substantial heterogeneity in the decidual lymphoid and myeloid cell lineages that shape gestational-specific immune networks and putative differentiation trajectories over time during gestation. Uncovering the overall complexity at the maternal-fetal interface throughout pregnancy resulted in a human atlas that may serve as a foundation upon which comprehension of the immune microenvironment and alterations thereof in pregnancy complications can be built.

Maternal and fetal T cells in term pregnancy and preterm labor

Pregnancy is a state of immunological balance during which the mother and the developing fetus must tolerate each other while maintaining sufficient immunocompetence to ward off potential threats. The site of closest contact between the mother and fetus is the decidua, which represents the maternal-fetal interface. Many of the immune cell subsets present at the maternal-fetal interface have been well described; however, the importance of the maternal T cells in this compartment during late gestation and its complications, such as preterm labor and birth, has only recently been established. Moreover, pioneer and recent studies have indicated that fetal T cells are activated in different subsets of preterm labor and may elicit distinct inflammatory responses in the amniotic cavity, leading to preterm birth. In this review, we describe the established and proposed roles for maternal T cells at the maternal-fetal interface in normal term parturition, as well as the demonstrated contributions of such cells to the pathological process of preterm labor and birth. We also summarize the current knowledge of and proposed roles for fetal T cells in the pathophysiology of the preterm labor syndrome. It is our hope that this review provides a solid conceptual framework highlighting the importance of maternal and fetal T cells in late gestation and catalyzes new research questions that can further scientific understanding of these cells and their role in preterm labor and birth, the leading cause of neonatal mortality and morbidity worldwide.

Immune tolerance at the maternal-placental interface in healthy pregnancy and pre-eclampsia

AIM

The objective of this review is to describe the immunological mechanisms which facilitate maternal tolerance at the maternal-placental interface, and to discuss how these mechanisms are disrupted in pre-eclampsia.

METHODS

A literature review was performed based on the analysis of papers available on PubMed. The most important and relevant studies regarding the immunological mechanisms which facilitate maternal tolerance in healthy pregnancy and pre-eclampsia are presented in this article.

RESULTS

The maternal-placental interface is the site where the immune tolerance begins and develops. Within the innate immunity, natural killer cells, macrophages and dendritic cells play a pivotal role in tolerance through regulation of inflammation. On the other hand, within the adaptive immunity, the correct increase of regulatory T cells is crucial for ensuring immune tolerance toward placental cells. Disturbances in maternal tolerance can lead to the appearance of pregnancy complications such as pre-eclampsia, which has a considerable impact on perinatal morbidity and mortality.

CONCLUSION

Our partial knowledge of immunological mechanisms involved in tolerance at the maternal-placental interface indicates that pre-eclampsia is characterized by alterations of this maternal immune tolerance, which could represent the origin of the disease.

Uterine Immunity and Microbiota: A Shifting Paradigm

The female reproductive tract harbors distinct microbial communities, as in the vagina, cervical canal, uterus, and fallopian tubes. The nature of the vaginal microbiota is well-known; in contrast, the upper reproductive tract remains largely unexplored. Alteration in the uterine microbiota, which is dependent on the nutrients and hormones available to the uterus, is likely to play an important role in uterine-related diseases such as hysteromyoma, adenomyosis, and endometriosis. Uterine mucosa is an important tissue barrier whose main function is to offer protection against pathogens and other toxic factors, while maintaining a symbiotic relationship with commensal microbes. These characteristics are shared by all the mucosal tissues; however, the uterine mucosa is unique since it changes cyclically during the menstrual cycle as well as pregnancy. The immune system, besides its role in the defense process, plays crucial roles in reproduction as it ensures local immune tolerance to fetal/paternal antigens, trophoblast invasion, and vascular remodeling. The human endometrium contains a conspicuous number of immune cells, mainly Natural Killers (NK) cells, which are phenotypically distinct from peripheral cytotoxic NK, cells and macrophages. The endometrium also contains few lymphoid aggregates comprising B cell and CD8⁺ T cells. The number and the phenotype of these cells change during the menstrual cycle. It has become evident in recent years that the immune cell phenotype and function can be influenced by microbiota. Immune cells can sense the presence of microbes through their pattern recognition receptors, setting up host-microbe interaction. The microbiota exerts an appropriately controlled defense mechanism by competing for nutrients and mucosal space with pathogens. It has recently been considered that uterus is a non-sterile compartment since it seems to possess its own microbiota. There has been an increasing interest in characterizing the nature of microbial colonization within the uterus and its apparent impact on fertility and pregnancy. This review will examine the potential relationship between the uterine microbiota and the immune cells present in the local environment.

Are B cells altered in the decidua of women with preterm or term labor?

PROBLEM

The immunophenotype of B cells at the maternal-fetal interface (decidua) in labor at term and preterm labor is poorly understood.

METHOD OF STUDY

Decidual tissues were obtained from women with preterm or term labor and from non-labor gestational age-matched controls. Immunophenotyping of decidual B cells was performed using multicolor flow cytometry.

RESULTS

(a) In the absence of acute or chronic chorioamnionitis, total B cells were more abundant in the decidua parietalis of women who delivered preterm than in those who delivered at term, regardless of the presence of labor; (b) decidual transitional and naïve B cells were the most abundant B-cell subsets; (c) decidual B1 B cells were increased in women with either labor at term or preterm labor and chronic chorioamnionitis compared to those without this placental lesion; (d) decidual transitional B cells were reduced in women with preterm labor compared to those without labor; (e) naïve, class-switched, and non-class-switched B cells in the decidual tissues underwent mild alterations with the process of preterm labor; (f) decidual plasmablasts seemed to increase in women with either labor at term or preterm labor with chronic chorioamnionitis; and (g) decidual B cells expressed high levels of interleukin (IL)-12, IL-6, and/or IL-35.

CONCLUSION

Total B cells are not increased with the presence of preterm or term labor; yet, specific subsets (B1 and plasmablasts) undergo alterations in women with chronic chorioamnionitis. Therefore, B cells are solely implicated in the pathological process of preterm labor in a subset of women with chronic inflammation of the placenta. These findings provide insight into the immunology of the maternal-fetal interface in preterm and term labor.

Early Pregnancy Human Decidua is Enriched with Activated, Fully Differentiated and Pro-Inflammatory Gamma/Delta T Cells with Diverse TCR Repertoires

Pregnancy is a state where high and stage-dependent plasticity of the maternal immune system is necessary in order to equilibrate between immunosuppression of harmful responses towards the fetus and ability to fight infections. TCR γδ cells have been implicated in the responses in infectious diseases, in the regulation of immune responses, and in tissue homeostasis and repair. The variety of functions makes γδ T cells a particularly interesting population during pregnancy. In this study, we investigated the proportion, phenotype and TCR γ and δ repertoires of γδ T cells at the maternal–fetal interface and in the blood of pregnant women using FACS, immunohistochemistry and spectratyping. We found an enrichment of activated and terminally differentiated pro-inflammatory γδ T-cell effectors with specific location in the human decidua during early pregnancy, while no significant changes in their counterparts in the blood of pregnant women were observed. Our spectratyping data revealed polyclonal CDR3 repertoires of the δ1, δ2 and δ3 chains and γ2, γ3, γ4 and γ5 chains and oligoclonal and highly restricted CDR3γ9 repertoire of γδ T cells in the decidua and blood of pregnant women. Early pregnancy induces recruitment of differentiated pro-inflammatory γδ T-cell effectors with diverse TCR repertoires at the maternal–fetal interface.

Lectin histochemical analysis of uterine natural killer cells in normal, hydatidiform molar and invasive molar pregnancy

Uterine natural killer (uNK) cells have been hypothesized to serve a role in controlling trophoblast invasion and proliferation. The aim of the present study was to identify the distribution and number of uNK cells in normal pregnancy (NP), partial mole (PM), complete mole (CM) and invasive mole (IM). uNK cells were detected using dolichos biflorus agglutinin lectin immunohistochemistry in decidual and villous tissues from early NP (n=15), late NP (n=15), PM (n=22), CM (n=20) and IM (n=10). A scaled eye piece was used for cell counting to obtain semi-quantitative results. It was revealed that uNK cells were mainly located in the uterine deciduas of early NP. As pregnancy progressed, the number of decidual uNK cells significantly decreased. Decidual uNK cells of PM, CM and IM were located near blood vessel endothelial cells. No significant differences were detected with respect to the numbers of decidual uNK between early NP and PM. However, the number of decidual uNK cells was significantly reduced in CM and IM compared with early NP. The populations of decidual uNK cells were not significantly different between CM and IM. No uNK cells were detected in the villi of PM, CM or IM. The decrease of decidual uNK cells in late NP, CP and IM, compared with early NP, suggested that uNK cells served an important role in controlling trophoblast invasion and proliferation.

IFN type I and II induce BAFF secretion from human decidual stromal cells

B cell activating factor (BAFF) is a critical cytokine for maturation of immature B cells. In murine lymph nodes, BAFF is mainly produced by podoplanin-expressing stromal cells. We have previously shown that circulating BAFF levels are maximal at birth, and that farmers’ children exhibit higher BAFF levels in cord blood than non-farmers’ children. Here, we sought to investigate whether maternal-derived decidual stromal cells from placenta secrete BAFF and examine what factors could stimulate this production. We found that podoplanin is expressed in decidua basalis and in the underlying villous tissue as well as on isolated maternal-derived decidual stromal cells. Decidual stromal cells produced BAFF when stimulated with IFN-γ and IFN-α, and NK cells and NK-T-like cells competent of IFN-γ production were isolated from the decidua. Finally, B cells at different maturational stages are present in decidua and all expressed BAFF-R, while stromal cells did not. These findings suggest that decidual stromal cells are a cellular source of BAFF for B cells present in decidua during pregnancy.

Feto-maternal immune interaction at the placental level

A special interaction is established during pregnancy between the maternal immune system and fetal cells to allow the survival and the normal growth of the fetus. Fetal cells expressing paternal alloantigens are not recognized as foreign by the mother because of an efficient anatomic barrier and a local immunosuppression determined by the interplay of locally produced cytokines, biologically active molecules and hormones. A special balance between TH1 and TH2 lymphocytes has also been observed at the feto-maternal barrier that contribute to control the immune response at this level. An important role is played by trophoblast cells that act as a physical barrier forming a continuous layer and exert immunomodulatory function. Trophoblast cells have also been shown to express regulators of the complement system and to downregulate the expression of HLA antigens. Dysfunction of these cells leads to morphological and functional alterations of the feto-maternal barrier as well as to hormonal and immune imbalance and may contribute to the development of pathologic conditions of pregnancy, such as recurrent spontaneous abortions. Efforts are still needed to better understand the physiology of the feto-maternal interaction and the pathogenetic mechanisms responsible for tissue damage in pathologic conditions of pregrancy.

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

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

Dynamic changes in maternal decidual leukocyte populations from first to second trimester gestation

INTRODUCTION

Decidual leukocytes are critical to the development of the fetomaternal interface, regulating tolerance to the semi-allogeneic fetus and vascular transformation of the uterine spiral arteries. Despite the continuation of these processes beyond the first trimester of pregnancy, the second trimester has largely been unstudied, with investigation focusing on early gestation and term tissues. We sought to characterize changes in decidual leukocyte populations from first to second trimester.

METHODS

Multicolor flow cytometry was performed on isolated decidual leukocytes from elective terminations of pregnancy between 6 and 20 weeks of gestation for study of first (6-12 weeks) and second trimesters (13-20 weeks). Specific subpopulations were identified by comparison to isotype and fluorescent-minus-one (FMO) controls.

RESULTS

Decidual natural killer cells (CD56(+)CD16(-)CD3(-)) did not change in number, although a population of dNK with decreased CD56 brightness was observed in second trimester decidua. CD14(+)HLA-DR(+) macrophage numbers declined from first to second trimester (p = 0.031), yet a CD163(+)CD206(+) subset designating alternatively activated M2-like macrophages increased during the same period (p = 0.015). Intermediate CD205(+) dendritic cells demonstrated significant decline (p = 0.022), but immature CD209(+) and mature CD83(+) dendritic cells did not differ between trimesters. Total CD3(+) and CD3(+)CD4(+) T lymphocytes increased (p = 0.0079, p = 0.0028); CD3(+)CD8(+) T cells trended towards increase but did not differ significantly.

CONCLUSION

Several changes in leukocyte subsets are observed in the second trimester that promote a tolerogenic and angiogenic decidual microenvironment through mid-gestation.

Innate immunity, decidual cells, and preeclampsia

Preeclampsia (PE) manifested by hypertension and proteinuria complicates 3% to 8% of pregnancies and is a leading cause of fetal-maternal morbidity and mortality worldwide. It may lead to intrauterine growth restriction, preterm delivery, and long-term sequelae in women and fetuses, and consequently cause socioeconomic burden to the affected families and society as a whole. Balanced immune responses are required for the maintenance of successful pregnancy. Although not a focus of most studies, decidual cells, the major resident cell type at the fetal-maternal interface, have been shown to modulate the local immune balance by interacting with other cell types, such as bone marrow derived-immune cells, endothelial cells, and invading extravillous trophoblasts. Accumulating evidence suggests that an imbalanced innate immunity, facilitated by decidual cells, plays an important role in the pathogenesis of PE. Thus, this review will discuss the role of innate immunity and the potential contribution of decidual cells in the pathogenesis of PE.

Macrophages infiltrate the human and rat decidua during term and preterm labor: evidence that decidual inflammation precedes labor

Preterm delivery is the leading cause of perinatal mortality and morbidity. Current tocolytics target myometrial contractions, a late step in the labor cascade. Identifying earlier events in parturition may lead to more effective therapeutic strategies. We hypothesized that inflammatory events in decidua (the maternal-fetal interface), characterized by leucocyte infiltration, are an early event during term and preterm labor (PTL). Leucocyte abundance in decidua of human pregnancies was quantified following term labor and PTL (idiopathic and infection associated), in conjunction with investigation of temporal inflammatory events in rat uterus during the perilabor period and in PTL induced by mifepristone. In human decidua, macrophage numbers were 4-fold higher in term labor (P < 0.01) and 2.5-fold higher in non-infection-associated PTL (P < 0.05) than in term nonlaboring samples. Neutrophil abundance was unchanged with labor but elevated in PTL with infection (5- to 53-fold increase; P < 0.01). T and NK cells were more abundant in idiopathic PTL than TL (P < 0.05). In rat, decidual macrophage infiltration increased 4.5-fold 12 h prior to labor and remained elevated during labor and early postpartum (P < 0.01). Decidual infiltration preceded that of the myometrium and was 4-fold higher (P < 0.01). In rat PTL, decidual macrophage numbers were also elevated (P < 0.01) and exceeded those of the myometrium (P < 0.05). These studies show for the first time that leucocytes infiltrate decidua during labor at term and preterm, supporting a role for leucocyte-derived inflammatory mediators in decidual activation. In the rat, this occurred prior to labor, suggesting it is an early event during parturition and thus a potential target for intervention.

Persistence of decidual NK cells and KIR genotypes in healthy pregnant and preeclamptic women: a case-control study in the third trimester of gestation

BACKGROUND

Natural Killer (NK) cells are the most abundant lymphocytes in the decidua during early gestation. The interactions of NK cells with the extravillous cytotrophoblast have been associated with a normal spiral artery remodeling process, an essential event for a successful pregnancy. Recent data indicate that alterations in the amount of decidual NK (dNK) cells contribute to the development of preeclampsia (PE). Moreover, genetic studies suggest that Killer Immunoglobulin-like Receptors (KIR) expressed in dNK cells influence the susceptibility to PE. Although dNK cells have been well characterized during early pregnancy, they have been scarcely studied in the third trimester of gestation. The aim of this work was to characterize dNK cells at the last trimester of gestation and to analyze the KIR genotype of healthy and PE women.

METHODS

Decidual samples were obtained during Caesarean section from control (n = 10) and PE (n = 9) women. Flow cytometric analysis of CD3, CD56, CD16 and CD9 was used to characterize and quantify dNK cells in both groups. Cell surface markers from decidual leukocytes were compared with PBMC from healthy donors.KIR genotyping was performed in genomic DNA (control, n = 86; PE, n = 90) using PCR-SSP.

RESULTS

The results indicate that dNK cells persist throughout pregnancy. They represented 20% of total leukocytes in control and PE groups, and they expressed the same cell surface markers (CD3-, CD56+, CD16- and CD9+) as dNK in the first trimester of gestation. There were no significant differences in the percentage of dNK cells between control and PE groups. The analysis of KIR gene frequencies and genotypes was not statistically different between control and PE groups. The ratio of activating to inhibitory genes indicated that the overall inhibitory balance (0.2-0.5) was more frequent in the PE group (control, 31.3% vs PE, 45.5%), and the activating balance (0.6-1.1) was more frequent in the control group (control, 68.6% vs PE, 54.4%). However this difference was not significant.

CONCLUSION

We demonstrated the persistence of dNK cells in PE and control women at the third trimester of pregnancy; these dNK cells had a similar phenotype to those found during early pregnancy. The predominance of a KIR inhibitory balance in the PE group could be associated to the physiopathology of PE.

Immune cells and molecules in pregnancy: friends or foes to the fetus?

Considering allograft rejection as a basic feature of the immune system, the mammalian pregnancy is an immunological paradox where the semi-allogeneic fetus is not rejected. How are the demands of pregnancy solved in the context of maternal immunity? Medawar's original proposal of maternal immune inertness during pregnancy should be revised to active materno-placental tolerance. Multiple mechanisms are involved in peripheral and local tolerance induction that prevents fetal rejection while maintaining competent immune surveillance and protection. The goal of this review is to discuss the major cellular and molecular components of the immune system that control and promote fetal survival.

Decidual leucocyte populations in early to late gestation normal human pregnancy

Most research on human decidual leucocytes to date has focused on the predominant CD56+ uterine natural killer (uNK) cell population in early pregnancy. Few reports have documented decidual leucocyte populations after 13 weeks gestation and in late pregnancy. Placental bed (decidua basalis) and non-placental bed (decidua parietalis) biopsies from normal pregnancies were taken from women undergoing termination of pregnancy in the 1st and 2nd trimesters and following Caesarean section in the 3rd trimester. Immunohistochemistry was used to quantify the numbers of decidual cells expressing CD56, CD3, CD8, CD94, NKG2A and CD14 and double labelled CD161+CD3+ NKT-like cells. Although a significant reduction in CD56+ uNK cells was found in 3rd trimester samples compared with 1st and 2nd trimester decidua, a substantial residual CD56+ leucocyte population was identified in 3rd trimester decidua. Expression of the KIR CD94/NKG2A mirrored that of CD56 at all gestational ages, providing an explanation for the absence of cytotoxic responses at the fetal-maternal interface. There was no difference in leucocyte populations between decidua basalis and decidua parietalis. Double immunohistochemical labelling revealed small numbers of decidual CD3+CD56+ and CD8+CD56+ cells, which decreased in number at term, and CD161+CD3+ cells, which increased in number at term. No differences in leucocyte populations were detected between decidua parietalis and decidua basalis. In contrast to previous reports, a substantial residual CD56+ cell population was demonstrated in 3rd trimester decidua. Decidual cytotoxic T-lymphocytes did not alter in number during gestation, while in contrast CD14+ macrophages decreased at term, representing the smallest decidual population assessed.

Altered decidual leucocyte populations in the placental bed in pre-eclampsia and foetal growth restriction: a comparison with late normal pregnancy

Alterations in the balance of leucocyte populations in uterine decidua may lead to the generation of an unfavourable cytokine environment that is associated with unsuccessful pregnancy. Single and double immunohistochemical labelling was used to examine leucocyte populations in decidua from normal third trimester, foetal growth-restricted and pre-eclamptic pregnancies. Placental bed biopsies from 12 women undergoing elective Caesarean section with no hypertension or foetal growth restriction (FGR), 8 women with FGR without maternal hypertension and 12 women with pre-eclampsia (PE) were used to quantify decidual CD56+ uterine NK cells, CD14+ macrophages, CD3+T-lymphocytes and CD8+ lymphocytes. CD3+CD56+, CD8+CD56+ and CD161+CD3+ double-labelled cells in decidua were compared in PE and control decidua. Decidual CD3+T-lymphocytes (P<0.01), CD8+ cytotoxic T-lymphocytes (P<0.05), CD14+ macrophages (P<0.0001) and CD56+ uterine natural killer (uNK) cells (P=0.01) were decreased in placental bed biopsies from women with PE compared with control third trimester decidua. By contrast, only CD56+ uNK cells were decreased in FGR decidua (P<0.05). Double-positive CD8+CD56+ cells were also decreased in PE compared with control third trimester decidua (P<0.05). The reduction in specific leucocyte subset numbers in PE and uNK cells in FGR suggests that altered local cytokine balance may be important in defective trophoblast invasion and spiral artery transformation in these pathological pregnancies.

Expression and function of PDCD1 at the human maternal-fetal interface

The failure to reject the semiallogenic fetus by maternal T lymphocytes suggests that potent mechanisms regulate these cells. PDCD1 is a CD28 family receptor expressed by T cells, and its ligand CD274 is strongly expressed by trophoblast cells of the human placenta. In this study, we examined whether human maternal T cells express PDCD1. Immunofluorescence examination of uterine tissues revealed PDCD1 expression on CD3+ cells was low in nonpregnant endometrium but increased in first-trimester decidua and remained elevated in term decidua (P < 0.05). In addition, higher relative proportions of term decidual CD8 bright, CD4+, and regulatory T cells expressed PDCD1 in comparison to autologous peripheral blood (P < 0.05). Term decidual T cells also expressed full-length and soluble PDCD1 mRNA isoforms more abundantly than their peripheral blood counterparts (P <or= 0.05). We also examined the effects of PDCD1:CD274 interactions in decidual T cells. Jar choriocarcinoma cells were transfected with CD274 and cocultured with activated decidual CD4+ or CD8 bright T cells for 72 h followed by analysis of cytokine concentration and decidual T cell apoptosis. Compared with empty vector-transfected cells, CD274-transfected Jar cells caused a significant suppression of interferon gamma and tumor necrosis factor alpha production by CD4+ (P < 0.05) but not CD8 bright T cells, while having no effect on secretion of IL10 or T cell apoptosis. These results suggest that the PDCD1:CD274 pathway functions in modification of maternal decidual lymphocyte cytokine secretion during pregnancy.

Systemic inflammatory priming in normal pregnancy and preeclampsia: the role of circulating syncytiotrophoblast microparticles

Systemic inflammatory responsiveness was studied in normal human pregnancy and its specific inflammatory disorder, pre-eclampsia. Compared with nonpregnancy, monocytes were primed to produce more TNF-alpha throughout normal pregnancy, more IL-12p70 in the first and second trimesters, and more IL-18 in the first trimester only. Intracellular cytokine measurements (TNF-alpha and IL12p70) showed little change by comparison. IFN-gamma production was suppressed in all three trimesters. In pre-eclampsia, IL-18 secretion was increased. Secreted but not intracellular measures of TNF-alpha and IL-12p70 were also further enhanced compared with normal pregnancy. Inhibition of IFN-gamma production was lost and involved both CD56(+) NK and CD56(-) lymphocyte subsets. We determined whether circulating syncytiotrophoblast microparticles (STBM) could contribute to these inflammatory changes. Unbound STBM could be detected in normal pregnancy by the second trimester and increased significantly in the third. They were also bound in vivo to circulating monocytes. Women with pre-eclampsia had significantly more circulating free but not cell-bound STBMs. STBMs prepared by perfusion of normal placental lobules stimulated production of inflammatory cytokines (TNF-alpha, IL12p70, and IL-18 but not IFN-gamma) when cultured with PBMCs from healthy nonpregnant women. Inflammatory priming of PBMCs during pregnancy is confirmed and is established by the first trimester. It is associated with early inhibition of IFN-gamma production. The inflammatory response is enhanced in pre-eclampsia with loss of the IFN-gamma suppression. Circulating STBMs bind to monocytes and stimulate the production of inflammatory cytokines. It is concluded that they are potential contributors to altered systemic inflammatory responsiveness in pregnancy and pre-eclampsia.

Establishment of the Porcine Epitheliochorial Placenta Is Associated with Endometrial T-Cell Recruitment

PROBLEM

We assessed implantation-associated quantitative changes in peripheral blood and endometrial T lymphocytes throughout epitheliochorial placenta formation.

METHOD OF STUDY

T-cell subsets were investigated in 10-, 15-, 20-, 30-, and 40-day pregnant and non-pregnant sows by flow cytometry and immunohistochemistry.

RESULTS

Endometrial total T, T cytotoxic (Tc), and T helper (Th) cells were in peak numbers at the attachment phase of implantation and Tc cells persisted in high proportions up to placental establishment. The number of gammadelta T lymphocytes was relatively small and implantation-independent. In situ, T cells increased in number with the advancement of implantation and formed T-cell clusters with implantation phase-dependent location. Percentages of peripheral blood T cells were not significantly changed throughout the implantation.

CONCLUSION

Superficial and adeciduate implantation of pigs has a profound effect on the number of total T, Tc, and Th cells and pattern of distribution of endometrial T cells in situ.

Expression profile and clonality of T-cell receptor beta variable genes in normal human endometrium

PROBLEM

In spite of their key immunological role, alphabeta+ T cells residing in endometrium have not been extensively explored. We analyzed here expression profile of TCRBV genes in normal human endometrium compared with peripheral blood.

METHODS

Samples were taken from normal reproductive women. RT-PCR using BV-gene specific primers was performed on blood and endometrial samples. After blotting, hybridization with radiolabelled probe and autoradiography, relative expression of each TCRBV family was determined. Clonal expansions of the over-expressed genes were assessed by CDR3 length polymorphism.

RESULTS

Only one gene (TCRBV7) was expressed significantly and two other genes marginally more in the endometrium compared with blood. All three TCRBV genes examined showed a rather restricted pattern in the endometrium in contrast to polyclonal patterns in the blood.

CONCLUSION

Our results stress the similarities between T cells residing in different mucosal tissues and provide a basis for future investigations about endometrial T cells and their antigen specificities in gynecological problems.

Changes in systemic type 1 and type 2 immunity in normal pregnancy and pre-eclampsia may be mediated by natural killer cells

A bias of T cell immunity towards type 2 (Th2) is thought to be critical for normal pregnancy. Pathological pregnancies, such as pre-eclampsia, are characterised by cell-mediated (Th1) immune dominance. The Th1/Th2 paradigm, however, is too simplistic. Normal pregnancy is associated with a systemic inflammatory response which increases throughout gestation. This inflammatory response is exaggerated in pre-eclampsia, a syndrome of the third trimester. T helper (Th) cells are considered the primary mediators of these altered immune responses, and other T cells, i.e. T cytotoxic (Tc) cells, and lymphocytes of the innate immune system, i.e. natural killer (NK) and NKT cells, have been largely disregarded. In this study, we have used novel pan type 1 (IL-18 receptor) and pan type 2 (ST2L) lymphocyte function markers in four-colour flow cytometry to broadly characterise peripheral blood lymphocyte populations from non-pregnant, normal pregnant and pre-eclamptic women. There were no changes in the Th1/Th2 or Tc1/Tc2 cell ratios between the three groups; however, the NK1/NK2 and NKT1/NKT2 cell ratios were significantly decreased in normal pregnancy compared with non-pregnant (p <0.001 and p <0.01, respectively) and pre-eclamptic women (p <0.05). These results confirm that immunoregulation occurs in pregnancy, but suggest a dominant role of the innate rather than the adaptive immune system.

Latest advances in understanding preeclampsia

Preeclampsia is a relatively common pregnancy disorder that originates in the placenta and causes variable maternal and fetal problems. In the worst cases, it may threaten the survival of both mother and baby. We summarize recent work on the causes of preeclampsia, which reveals a new mode of maternal immune recognition of the fetus, relevant to the condition. The circulating factors derived from the placenta, which contributes to the clinical syndrome, are now better understood. This brief review on preeclampsia does not cover all aspects of this intriguing condition but focuses on some new and interesting findings.

Immunohistochemical characterization of endometrial leucocytes in endometritis

AIMS

Leucocytes are a normal and variable component of the endometrial stromal cell population. The aim of this study was to characterize endometrial leucocytes in established cases of endometritis in order to determine whether there are objective characteristics of the leucocyte infiltrate which would allow its identification as part of an inflammatory process rather then the normal physiological leucocyte infiltrate.

METHODS AND RESULTS

We examined endometrial tissue from 79 cases of endometritis and 22 histologically normal controls. Leucocytes were characterized immunohistochemically for CD45, CD20, CD68, CD3 and CD56 and numbers were analysed semiquantitatively on a scale of 0-4. In many endometritis cases the overall number of leucocytes was increased. Furthermore, leucocytes were unusually distributed with a tendency to accumulate superficially beneath the endometrial surface. Whilst numbers of macrophages, T lymphocytes and endometrial granulated lymphocytes (uterine natural killer cells) did not differ between endometritis samples and controls, most endometritis cases contained a substantially increased number of B cells, which normally represent 1% or less of the endometrial leucocyte population. B lymphocytes were also observed in unusual locations such as intraepithelially and within glandular lumina.

CONCLUSIONS

These results suggest that immunohistochemical characterization of endometrial leucocytes may be helpful in establishing a diagnosis of endometritis in equivocal cases.

Human uterine natural killer cells: a reappraisal

The presence of granulated cells within the uterus of many species has been recognised for many years but only recently have these been recognised to be a type of NK cell. Various terms have been applied to the cells, including endometrial granulocyte, K cell and, in mouse and rat, granulated metrial gland cell. Although early studies are often based on histology and electron microscopy, these often include important information for current studies. In vitro studies of purified cells have focused particularly on cytotoxicity and cytokine production and roles in the control of trophoblast invasion and spiral artery remodelling in human pregnancy have been proposed. Evidence in mouse has implicated uNK cell production of IFN-gamma in vascular remodelling but evidence for such a role for human uNK cells remains to be established. Investigation of uNK cells in human pregnancy is hampered by the lack of availability of tissues from the first half of the second trimester of pregnancy when vascular remodelling occurs and also by possible differences between cells from different regions of decidua. The presence of similar cells in species with no trophoblast invasion into the uterus and epitheliochorial placentation raises the question of whether control of trophoblast invasion by human uNK cells is important in vivo and raises the possibility of another function which is conserved between species.

Regulation of Numbers of Macrophages in the Endometrium of the Sheep by Systemic Effects of Pregnancy, Local Presence of the Conceptus, and Progesterone

Many species exhibiting hemochorial placentation experience an accumulation of macrophages in the endometrium during pregnancy. For the present study, it was tested whether macrophages also accumulate in the endometrium of the sheep, which is a species undergoing an epitheliochorial placentation. An additional objective was to determine whether regulation of endometrial macrophage number occurs via systemic or local signals and whether progesterone is one of these signals. The approach was to evaluate presence of macrophages immunohistochemically using antibodies to CD68 and CD14. Tissues examined were from cyclic ewes in the luteal phase of the estrous cycle, unilaterally-pregnant ewes at day 140 of pregnancy in which pregnancy was surgically confined to one uterine horn, ovariectomized ewes, and ovariectomized ewes treated with progesterone for 44 days. Macrophages were localized predominately to the stromal compartment of the stratum compactum region of the endometrium. In non-pregnant ewes, macrophages were not abundant regardless of physiological status. Increased numbers of endometrial macrophages were seen for both the pregnant and non-pregnant uterine horns of unilaterally pregnant ewes. Numbers of macrophages were higher in the endometrium from the pregnant uterine horn than from endometrium from the non-pregnant uterine horn. Results indicate that macrophages accumulate in the endometrium by day 140 of pregnancy in the sheep and that this induction is because of both systemic and local signals. Progesterone appears not to be an important regulator of numbers of endometrial macrophages.

[Adaptation of the immune system as a response to pregnancy]

INTRODUCTION

Pregnancy is an intriguing immunologic phenomenon. In spite of genetic differences, maternal and fetal cells are in close contact over the whole course of pregnancy with no evidence of either humoral and/or cellular immunologic response of mother to fetus as an allotransplant. The general opinion is that the fundamental protective mechanism must be located locally at the contact-plate, between the maternal and fetal tissues. Immunologic investigations proved the presence of specific systems which block the function of antipaternal maternal antibodies, as well as formation of cytotoxic maternal T-cells to paternal antigens. The system preventing rejection of graft during pregnancy is functioning at the level of maternal and fetal tissues. The protective mechanisms are coded by genes of MCH region, locus HLA-G.

PROTECTIVE MECHANISMS IN THE PLACENTA

The placenta protects itself against antibody-mediated damage. A high level of complement-regulatory proteins (CD46, CD55 and CD59), being the response to the synthesis of complement-fixing maternal antibodies to paternal antigens and regulation of the placental HLA expression as a preventive reaction of the feto-placental unit to the influence of maternal CTL, are the most important protective mechanisms of placenta.

PROTECTIVE MECHANISMS SHARED BY THE PLACENTA AND UTERUS

Protective mechanisms common both for placenta and uterus are as follows: expressions of Fas ligand prevention of infiltration of activated immune cells, regulation of immunosuppression which prevents proliferation of immune cells and high natural immunity (Na cells and macrophages) of the decidua.

Conceptus influences the distribution of uterine leukocytes during early porcine pregnancy

Pregnancy in humans and rodents is associated with dramatic changes in leukocyte populations within the uterus. In these species, recruitment of leukocytes, mostly natural killer (NK) lymphocytes, accompanies decidualization of endometrial stroma even in the absence of pregnancy. In the pig, a nondecidualizing species, the predominant lymphocytes in the pregnant uterus are T and/or NK cells, but their distribution relative to embryonic attachment sites has not been reported. The objective of this study was to compare the abundance of leukocytes in porcine endometrium in contact with trophoblast with that between attachment sites during the early postattachment period. Uteri were recovered on Days 15-17 (n = 4), 18 and 19 (n = 4), 21 and 22 (n = 5), and 25-27 (n = 2) of gestation and from cycling pigs during the luteal phase (Day 15; n = 3). Leukocytes were identified in uterus obtained at versus between attachment sites using an antibody reactive with all leukocytes (CD44). In all pregnant animals, leukocytes were diffusely scattered throughout the endometrial stroma but were rare or absent in the luminal epithelium. Leukocyte density was approximately 3-fold greater in endometrium in contact with conceptuses than in endometrium between attachment sites throughout the early postattachment period. Leukocyte density during the luteal phase was similar to that between attachment sites, suggesting that leukocyte recruitment was a localized response to the embryo. The ability of an individual porcine conceptus to recruit maternal leukocytes to the adjacent stroma may be a vital step in early placental development and embryo survival.

Involvement of granule-mediated apoptosis in the cyclic changes of the normal human endometrium

Our objective is to investigate the involvement of granule-mediated apoptosis in the cyclic changes of the endometrium. We demonstrated the localization of CD56, perforin, granzyme B and caspase-3 in the endometrium by immunohistochemistry. We also confirmed the localization of perforin by immuno-electron microscopy, and demonstrated apoptosis in endometrial glandular cells by TdT-mediated dUTP-biotin nick end labeling (TUNEL) and electron microscopy. Uterine CD56-positive natural killer (NK) cells expressed perforin and granzyme B in its cytoplasm. Uterine NK cells increased significantly in the endometrial stroma during the secretory phase, and peaked during the late secretory phase. These cells started decreasing in number during the menstrual period. In endometrial glandular cells, caspase-3 and TUNEL-positive cells increased significantly from the late secretory phase, with apoptosis reaching a peak during the menstrual period. Using electron microscopy, we observed uterine NK cells with chromatin rich, segmented nuclei and intracytoplasmic granules in the stroma obtained from late secretory phase endometria. These cells extended projections to the lining of endometrial glandular cells and attached to form a cell-to-cell contact. In addition, nuclear chromatin was observed to have already cohered and small cytoplasmic organelles were beginning to disappear, suggesting that these endometrial glandular cells were undergoing apoptosis. Utilizing immuno-electron microscopy, intracytoplasmic granules in uterine NK cells were stained with anti-perforin antibody. The findings of this study suggest that granule-mediated apoptosis in endometrial glandular cells induced by NK cells expressing perforin and granzyme B may be associated with the onset of menstruation.

Definitive molecular evidence of renin-angiotensin system in human uterine decidual cells

The tissue renin-angiotensin system (RAS) has been suggested to be present in human gestational tissues, but uncertainty exists about the authenticity of this RAS, and the cellular origin of this RAS has not been defined. In the present study, we confirmed the presence of authentic renin and angiotensinogen in the prolactin-producing decidual tissue by sequencing the cDNAs generated through reverse transcription-polymerase chain reaction, confirming cDNA product sizes, and by performing Northern blot analysis of the RNA. Our comparative data demonstrate that prolactin has the highest expression in the decidual tissue, followed by renin, and that angiotensinogen has the least expression. We demonstrated with fluorescent in situ hybridization that prolactin-expressing endocrine decidual cells are the same cells that express both renin and angiotensinogen. These results have implications in regard to how the decidual RAS may be regulated and what potential role this local RAS may have in the pathogenesis of preeclampsia.

The effect of hormone replacement therapy on the number and the proliferation index of endometrial leukocytes

This study aimed to determine the changes in endometrial leukocyte subpopulations under sequential hormone replacement therapy (HRT) during the late progestogenic phase. The number of leukocytes was determined using immunohistochemistry utilizing monoclonal antibodies to CD45 (total leukocytes), CD56 (endometrial granulated lymphocytes), CD3 (T-cells), and CD68 (macrophages). Leukocyte proliferation was demonstrated using in-situ hybridization with a histone probe, and the proliferation index was determined using double labelling for Ki67 (Mib1). Compared to the corresponding phase of the physiological cycle, sequential HRT-treated endometrium exhibited a 95% increase in CD45(+) cells (P < 0.05), a 130% increase in CD56(+) cells (P < 0.05), and a 113% increase in CD3 cells. There was a non-statistically significant drop in the number of CD68(+) cells. The number of proliferating leukocytes increased in sequential HRT endometrium.

Chronic chorioamnionitis: a clinicopathologic and immunohistochemical study

Lymphocytic inflammation of the fetal membranes is unusual and has been termed chronic chorioamnionitis. We report the clinicopathologic and immunohistochemical findings in 31 placentas with chronic chorioamnionitis. The most common histopathologic association was chronic villitis of unknown etiology, which was identified in 22 (71%) of the 31 placentas. The severity of the chronic villitis did not correlate with the severity of chronic chorioamnionitis. Additional placental findings included chronic intervillositis in two, fetal vessel thrombosis in five, hemorrhagic endovasculitis in four, decidual chronic vasculitis in three, and atherosis in one. Maternal history included pregnancy-induced hypertension in six and diabetes in one. Twelve infants were preterm, and five had intrauterine growth retardation. There was no neonatal sepsis or death. Immunohistochemical staining in areas of chronic chorioamnionitis showed CD3+ and CD8+ cells present in moderate numbers, and CD4+ cells in smaller numbers. CD20+ and CD56+ cells were rare or absent. Chronic chorioamnionitis is commonly associated with chronic villitis of unknown etiology, shares similar clinical associations, and may have a related cause, possibly immunologic.

Maternal scleroderma: placental findings and perinatal outcome

Pregnancy after the onset of scleroderma is uncommon; therefore, placental findings and perinatal outcome have rarely been correlated. The histopathologic features of placentas from 13 pregnancies in eight women with scleroderma were recorded and correlated with the clinical features of the mother and fetus. Adverse perinatal outcome included intrauterine fetal demise in five, and previable or preterm delivery in four. A decidual vasculopathy was seen in 5 of the 13 placentas, four of which were associated with intrauterine fetal demise. Decidual blood vessels in the scleroderma patients were evaluated immunohistochemically for platelet-derived growth factor (PDGF), transforming growth factor beta1 (TGF-beta1), T-helper and T-suppressor lymphocytes, macrophages, immunoglobulin (Ig) M, and IgG, and compared with those from hypertensive and uncomplicated third-trimester pregnancies. The atherotic blood vessels in scleroderma were characterized by mural macrophages and IgM and IgG deposition and were similar to those seen in placentas from hypertensive pregnancies. CD8-positive T cells predominated in normal and hypertensive decidua compared with scleroderma, in which CD4-positive T cells were more frequent. No difference in PDGF or TGF-beta1 staining was found between scleroderma and control groups. In conclusion, decidual vasculopathy is common in scleroderma, is similar to that seen in hypertension, and is associated with poor perinatal outcome. A trend toward a reversed ratio of decidual CD4 to CD8-positive T cells is seen in scleroderma compared with hypertension and uncomplicated pregnancies. PDGF and TGF-beta1 do not appear to be involved in the pathogenesis of decidual vasculopathy in scleroderma.

Expression of membrane form of the pregnancy associated protein TJ6 on decidual lymphocytes in the first trimester of pregnancy

TJ6, a newly described protein produced locally in the uterine decidua during pregnancy, may be involved in maintaining a unique immunological environment at the maternal-fetal interface. The aim of this study was to determine whether TJ6 is expressed as membrane form on decidual lymphocytes (DL), to define the phenotypes of TJ6m (membrane form TJ6) expressing cells and to analyze the fluorescence intensity of TJ6m expression. Peripheral blood lymphocytes (PBL) and DL were obtained from first trimester pregnancies undergoing elective termination and immunophenotyped for TJ6m and other cell surface antigens (CD3, CD8, CD19, CD56, CD16) by flow cytometry. This is the first study showing that TJ6 molecules are present on decidual lymphocytes in human pregnancy. TJ6m expression on PBL was not different from that of DL. However, a significantly higher percentage of double positive (TJ6m+CD3+, TJ6m+,CD8+,TJ6m+CD19+) cells were found in PBL when compared to DL. The average fluorescence intensity (AFI) for the TJ6m marker among cells with CD8+, CD19+ and CD56+ double positive was significantly higher in DL as compared with those of PBL. The AFI for granularity of double positive DL was significantly higher than observed in PBL.

Immunohistochemical characterization of leukocytic subpopulations in chronic endometritis

Objective: We analyzed the histologic and immunohistochemical changes in the endometrial leukocytic subpopulations to determine which of them are characteristic of chronic endometritis.

Results: Endometrial biopsies from 25 cases of chronic endometritis and 35 controls were studied. Characteristic morphologic findings included the presence of a plasma cell infiltrate, and a prominent, albeit non-specific, lymphocytic infiltrate in all patients with endometritis. A neutrophilic infiltrate was also noted in 90% of the patients. Other non-specific histologic findings included occasional prominent lymphoid aggregates, stromal edema, hemorrhage, and necrosis and cystic dilation of some glands in endometria of patients with chronic endometritis. Endometrial immune cells were investigated immunohistochemically using antibodies to CD3 (pan-T), CD20 (pan-B, L26), and Ham-56 (macrophage). In control patients, endometrial immune cells were predominantly composed of CD3 and Ham-56 positive cells. CD20 positive cells comprised <2% of immune cells in control patients [mean: <2 cells/high power field (HPF)]. Large numbers of CD20 and CD3 lymphocytes were seen in endometria of patients with chronic endometritis. A semiquantitative analysis showed that the numbers of CD20 and CD3 positive cells in patients with chronic endometritis were increased 50- and 3-fold, respectively, when compared to those of control patients (mean B cells: 49 vs. 2 cells/HPF; mean T cells: 149 vs. 45 cells/HPF). CD20 positive cells were predominantly seen in subepithelial and periglandular aggregates. CD3 positive cells had a predominant stromal distribution and an occasional intra- or subepithelial localization. There was no difference in the number and distribution of Ham-56 positive cells in patients with or without endometritis.

Conclusions: These findings suggest that CD20 cells may have a significant role in the pathogenesis of chronic endometritis and that immunostaining for B and T lymphocytes could be used in confirming the diagnosis of endometritis or in diagnosing subclinical or progressing endometritis in which plasma cells could not be detected or are rarely identified.

Interleukin-1 beta induces cyclooxygenase-2 in cultured human decidual cells

PROBLEM

The purpose of this study was to examine the hypothesis that interleukin-1 beta (IL-1 beta)-elicited increases in decidual prostaglandin E2 and F2 alpha (PGE2 and PGF2 alpha) biosynthesis are due to the de novo expression of the inducible isoform of cyclooxygenase (i.e., COX-2).

METHOD

Primary human decidual cell cultures were established from term placentas delivered by cesarean section. After 8 days in vitro, when the cultures secreted immunoreactive prolactin, the cells were incubated for 24 h in serum-free medium, and then challenged with IL-1 beta from 1 to 48 h. PGE2 and PGF2 alpha content in the media were measured by specific radioimmunoassays.

RESULTS

IL-1 beta stimulated a time-dependent enhancement in PGE2 and PGF2 alpha production, with PGF2 alpha synthesis predominating over PGE2. IL-1 beta also induced a dose-dependent increase in the output of both arachidonic acid metabolites. When Northern blots of IL-1 beta-treated and control cells were probed with cDNAs encoding either COX-1 or COX-2 isoforms or an oligonucleotide probe encoding a portion of the human beta-actin, we detected a time- and dose-dependent increase in the steady-state levels of COX-2, but not COX-1 or beta-actin mRNA transcripts. Moreover, the expression of COX-2 mRNA in IL-1 beta-stimulated cells was superinduced by preincubation with cycloheximide, but completely abolished by actinomycin D.

CONCLUSIONS

Taken together, the data suggest that COX-2 mRNA expression is largely responsible for the robust increase in PG formation seen in IL-1 beta-treated decidual cells.

Characteristics of perforin expressing lymphocytes within the first trimester decidua of human pregnancy

PROBLEM

The number of perforin (P)-positive cells in decidua of pregnancy is larger than that observed in any other pathological condition. The aim was to investigate the distribution and the phenotype of P+ cells.

METHOD

Decidual tissue was obtained from the first trimester vaginal termination of pregnancy. Tissue distribution of P+ cells was analyzed by immunohistochemistry. The method for simultaneous measurement of P and cell surface is presented.

RESULTS

There is no difference in number and distribution of P+ cells between decidua basalis (DB) and decidua parietalis (DP). The percentage of P+ decidual lymphocytes (DL) is two times higher than in peripheral blood lymphocytes (PBL) (55% vs. 27%), and the prevalent phenotype is CD3- CD4- CD8- CD2+ (95%) CD11c+ (68%) and CD56+ (82%). CD56bright+ DL are also Pbright+ and this is the largest DL subpopulation (42.4% DL). Two different subpopulations of CD8+ DL exist: 1) CD8bright+, which are CD3+ CD56- P- and 2) CD8dim+, which are CD3- CD56+ P+.

CONCLUSION

P expressing DL are prevalently nonclassical NK cells (CD16-) with low cytolytic activity but fully equipped with potent cytolytic machinery (Pbright+). There are no classical cytotoxic lymphocytes (CTL) (CD3+ CD8+ P+) in the decidua, and all CD8+ P+ cells are CD3- CD56+. The number of P+ cells is even higher in DP in the vicinity of noninvasive trophoblast, than in DB.

Isolation of decidual lymphocytes from chorionic villus samples: phenotypic analysis and growth in vitro

PROBLEM

Giemsa stained cell isolates prepared from chorionic villus samples (CVS) contain granulated cells morphologically similar to large granular lymphocytes.

METHOD

Phenotypic characterization of these cellular isolates by two-color immunofluorescence and subsequent in vitro culture in the presence of recombinant interleukin-2 (rIL-2) were done in order to determine whether CVS could serve as a source of decidual lymphocytes.

RESULTS

A major fraction of the CVS-derived lymphocytes were characterized as decidual NK cells, exhibiting high levels of CD56 expression (CD56+bright), without concomitant expression of CD16. The T cell population present in CVS-derived lymphocytes contained both CD4+ and CD8+ cells in a ratio somewhat reduced compared to that found in peripheral blood. While both T cells and CD56+bright cells from CVS proliferate in vitro in response to rIL-2 alone, preferential growth of CD56+bright cells was accomplished using a selective culture technique wherein co-culture with an irradiated, B lymphoblastoid cell line promoted the growth of CD56+ cells.

CONCLUSION

CVS contains decidual NK cells and T cells that proliferate in response to rIL-2 and/or third party stimulator cells. These culture techniques will allow investigations into the maturation and/or activation of decidual NK cells and T cells.

Decidual-trophoblast interactions: decidual lymphoid cell populations in basal and parietal decidua

Immunohistochemical analysis of tissue specimens from human pregnancy decidua basalis in contact with invasive trophoblast of chorion frondosum and decidua parietalis in contact with non-invasive chorion laeve do not differ in the frequency of lymphoid cells of the following phenotypes (CD2, CD4, CD8, CD14, CD21 and gamma/delta TCR). A practical implication of this observation is that the collection of lymphoid cells from whole decidua by curettage for functional studies is justified.

Decidual-trophoblast interactions: decidual lymphoid cell function in normal, anembryonic, missed abortion and ectopic human pregnancy

This study was designed to investigate the consequences of decidua-trophoblast interactions on the phenotype, spontaneous and induced proliferation and immunoregulatory potential of decidual leukocytes in normal pregnancies (NP), anembryonic pregnancies (AP), missed abortions (MA) and ectopic pregnancies (EP). Spontaneous proliferation of decidual non-adherent cells (NAD) from pregnancies with viable trophoblast inside the uterus is significantly higher than proliferation of peripheral blood lymphocytes (PBL) from the same groups (P < 0.001 for NP; P < 0.05 for AP). Spontaneous proliferation of decidual NAD cells from NP was higher (P < 0.001) when compared with AP and EP. The induced (PHA and Con A) responses of PBL from women with normal and pathological pregnancies were significantly higher than that of decidual NAD cells (P < 0.001). Higher proliferation of NAD decidual cells was obtained when Con A-stimulated NP were compared with MA and EP (P < 0.01). The interaction of viable trophoblast with intrauterine decidua appears to be a prerequisite for the activation of NAD suppressor cells, since NAD cells from MA produced stimulation instead of suppression, and NAD cells from EP had no suppressive effect. On the contrary, both NAD and adherent (AD) decidual leukocytes from NP and AP produced very strong suppression of PHA or alloantigen-induced PBL proliferation. The contact between trophoblast and AD decidual leukocytes is not necessary for their suppressive function, since even higher suppression is obtained with the cells from ectopic pregnancies.