Alternative theories: Pregnancy and immune tolerance

The landscape of decidual immune cells at the maternal-fetal interface in parturition and preterm birth

BACKGROUND

Parturition is similar to an inflammatory response in which resident and infiltrating immune cells release cytokines and chemokines into the maternal-fetal interface, promoting expulsion of the fetus from the mother. The untimely activation of these inflammatory pathways can result in preterm labor. The maternal-fetal interface is composed mainly of decidual tissue and placental villous space.

OBJECTIVE

The objective of this review is to examine the role and mechanisms of decidual immune cells during parturition and preterm birth. A deeper understanding of decidual immune cells at the maternal-fetal interface could provide significant insight into parturition and preterm birth pathogenesis.

METHODS

We searched major databases (including PubMed, Web of Science, and Google Scholar etc.) for literature encompassing decidual immune cells, parturition and preterm birth up to July 2024 and combined with studies found in the reference lists of the included studies.

RESULTS

Decidual neutrophils release inflammatory mediators that facilitate parturition. The M1/M2 ratio of decidual macrophages increases among preterm birth population. Mast cells may cause uterine contractions. In parturition and preterm birth, there is an increase in CD56dimCD16+ natural killer cells and immature dendritic cells. The increase of Th1/Th2 and Th17/Treg cells leads to preterm birth. Women with preterm birth had a higher proportion of decidual B cells. ILC2 can help protect the steady-state environment at the maternal-fetal interface. The activation of invariant NKT cells plays an important role in inflammation-induced preterm birth. These decidual immune cells communicate with each other. The development of sequencing technology enables a more in-depth study of decidual immune cells.

CONCLUSION

The dynamic balance of the maternal-fetal immune microenvironment plays a crucial role in maintaining human pregnancy and in the initiation of delivery. A deep understanding of the mechanism of decidual immune dysfunction is crucial for understanding the pathogenesis of preterm birth.

Molecular and cellular morphology of placenta unveils new mechanisms of reproductive immunology

INTRODUCTION

Despite of numerous studies of the placenta, some molecular and cellular characteristics, particularly the relationship among different cell types, have not been well understood. We aim to investigate the basic and intricate details of cellular and molecular elements in early and late phase placentas to gain better understanding of the immune regulation of human reproductive process.

METHODS

A novel combination of techniques of spatial transcriptomics(ST), multiple immunohistochemistry, and a dual labeling combining immunohistochemistry and (fluorescence in situ hybridization) FISH on normal and ectopic pregnancy and animal models was employed to investigate the placenta at tissue, cell, protein and molecular levels and to trace the fetal and maternal origin of every cell in early and late placentas.

RESULTS

Original discoveries include early expression of immune checkpoint proteins in embryo trophoblasts even before implantation. The detailed distributional relationships among different cell types of fetal and maternal origins in placenta and decidua indicate an immune rejection of the mother towards the fetus and this was counterbalanced by immune inhibitory proteins and blocking antibody Immunoglobulin G4 (IgG4) at the junction between the fetus and the mother. In contrary to common believe, we found that vascular endothelial and glandular epithelial cells in the decidua remain maternal in origin and were not replaced by fetal cells. At term placenta, fetal immune cells infiltrated into the maternal side of the decidus and vice versa indicating a possible immune reaction between fetal and maternal immune systems and suggesting a possible immune mechanism for trigger of parturition. The ability of trophoblasts to create an immune suppressed environment was also supported by findings in ectopic pregnancy and the animal models.

CONCLUSION

The findings indicate a fetus-driven mechanism of immune balance involving both cellular and humoral immunity in human reproduction.

Interleukin in Immune-Mediated Diseases: An Updated Review

The immune system comprises various regulators and effectors that elicit immune responses against various attacks on the body. The pathogenesis of autoimmune diseases is derived from the deregulated expression of cytokines, the major regulators of the immune system. Among cytokines, interleukins have a major influence on immune-mediated diseases. These interleukins initiate the immune response against healthy and normal cells of the body, resulting in immune-mediated disease. The major interleukins in this respect are IL-1, IL-3, IL-4, IL-6, IL-10 and IL-12 which cause immune responses such as excessive inflammation, loss of immune tolerance, altered T-cell differentiation, immune suppression dysfunction, and inflammatory cell recruitment. Systemic Lupus Erythematosus (SLE) is an autoimmune illness characterized by dysregulation of interleukins. These immune responses are the signs of diseases such as rheumatoid arthritis, inflammatory bowel disease, psoriasis, type I diabetes, and multiple sclerosis.

Comparison of maternal and neonatal survival exposed to humidifier disinfectants during perinatal periods: a case-series study

A humidifier disinfectant (HD) has been prohibited by the government due to its serious effects on the human body. Several studies on the relationship between HD and lung diseases have been performed independently on children and adults. However, there have been no reports on the effects of HD exposure on pregnant women and their foetuses. Therefore, the present study was conducted to investigate the effects of HD exposure on the foetuses of women who encountered HD during pregnancy. A total of 56 cases were recruited from 2017 to 2019 through the Korea Environmental Industry & Technology Institute, and data obtained from the medical records included maternal date of birth, maternal date of death, maternal start and end date of HD exposure, maternal date of symptom onset, neonatal birthday, neonatal birthweight, gestational age, and neonatal survival status within 28 days. All data were retrospectively investigated through medical records. Of the 47 mothers, 20 (42.6%) mothers survived, and 27 (57.4%) mothers died. In the group of survivors, there was a shorter period of total HD use, period of HD use before pregnancy and period of HD use to onset of symptoms. Shorter durations of HD use resulted in higher survival rate of mothers. HD use caused an increase in gestational age surviving foetuses, and foetal mortality increased when clinical symptoms developed before birth.

Immunosequencing and Profiling of T Cells at the Maternal-Fetal Interface of Women with Preterm Labor and Chronic Chorioamnionitis

T cells are implicated in the pathophysiology of preterm labor and birth, the leading cause of neonatal morbidity and mortality worldwide. Specifically, maternal decidual T cells infiltrate the chorioamniotic membranes in chronic chorioamnionitis (CCA), a placental lesion considered to reflect maternal anti-fetal rejection, leading to preterm labor and birth. However, the phenotype and TCR repertoire of decidual T cells in women with preterm labor and CCA have not been investigated. In this study, we used phenotyping, TCR sequencing, and functional assays to elucidate the molecular characteristics and Ag specificity of T cells infiltrating the chorioamniotic membranes in women with CCA who underwent term or preterm labor. Phenotyping indicated distinct enrichment of human decidual effector memory T cell subsets in cases of preterm labor with CCA without altered regulatory T cell proportions. TCR sequencing revealed that the T cell repertoire of CCA is characterized by increased TCR richness and decreased clonal expansion in women with preterm labor. We identified 15 clones associated with CCA and compared these against established TCR databases, reporting that infiltrating T cells may possess specificity for maternal and fetal Ags, but not common viral Ags. Functional assays demonstrated that choriodecidual T cells can respond to maternal and fetal Ags. Collectively, our findings provide, to our knowledge, novel insight into the complex processes underlying chronic placental inflammation and further support a role for effector T cells in the mechanisms of disease for preterm labor and birth. Moreover, this work further strengthens the contribution of adaptive immunity to the syndromic nature of preterm labor and birth.

On antigen-specific signals, immune class regulation and energetics: Report III from the workshops on foundational concepts of immune regulation

This is a report from a one-week workshop held in Athens, Greece in July of 2022. The workshop aimed to identify emerging concepts relevant to the fundamentals of immune regulation and areas for future research. Theories of immune regulation emphasize the role of T cell help or co-stimulation (signal 2). The workshop participants considered how new data on the characteristics of agonist antigens, the role of the antigen receptor signals (signal 1) in driving fate decisions, the effect of energetics on immunity and a better understanding of class-control in the immune response, may impact theories of immune regulation. These ideas were discussed in the context of tumour immunology, autoimmunity, pregnancy and transplantation. Here we present the discussions as a narrative of different viewpoints to allow the reader to join the conversation. These discussions highlight the evolving understanding of the nature of specific antigen recognition and how both antigen-specific and non-specific mechanisms impact immune responses.

Maternal plasma and salivary anelloviruses in pregnancy and preterm birth

Introduction

Human anelloviruses, including torque teno virus (TTV) and torque teno mini virus (TTMV), are ubiquitous in the general population and have no known pathogenicity. We investigated the prevalence and viral load of TTV and TTMV in plasma and saliva over pregnancy, and assessed their association with spontaneous or medically indicated preterm birth.

Methods

This is a secondary analysis of the Measurement of Maternal Stress (MOMS) study, which recruited 744 individuals with singleton pregnancies from 4 US sites (Chicago, Pittsburgh, San Antonio, and rural Pennsylvania). Baseline outpatient visits took place in the second trimester (between 12'0 and 20'6/7  weeks' gestation), and follow-up visits in the third trimester (between 32'0 and 35'6/7  weeks' gestation). In a case-control study design, participants who delivered preterm (<37 weeks) resulting from spontaneous labor and/or preterm premature rupture of membranes ("sPTB") were compared with participants experiencing medically indicated preterm birth ("iPTB"), or delivery at term ("controls"). Plasma and saliva samples obtained during the second and third trimesters were tested for the presence and quantity of TTV and TTMV using real-time PCR. Demographic data were obtained via self-report, and clinical data via medical record review by trained research personnel.

Results

TTV was detected in plasma from 81% (second trimester) and 77% (third trimester) of participants, and in saliva from 64 and 60%. Corresponding detection rates for TTMV were 59 and 41% in plasma, and 35 and 24% in saliva. TTV and TTMV concentrations were similar between matched plasma and saliva samples. TTV prevalence and concentrations were not significantly different between groups (sPTB, iPTB, and controls). However, plasma TTMV in the third trimester was associated with sPTB and earlier gestational age at delivery. The iPTB group was not different from either the sPTB or the control group. In saliva, concentrations of TTV and TTMV were similar among the three groups. Both TTV and TTMV were more prevalent with increasing parity and were more common in Black and Hispanic participants compared to non-Hispanic White participants.

Conclusion

Anellovirus presence (specifically, TTMV) in the third trimester may be associated with preterm birth. Whether this association is causative remains to be determined.

Roles of human trophoblasts' pattern recognition receptors in host defense and pregnancy complications

The immune system in pregnancy is able to protect pregnant mothers and fetuses from pathogenic microorganisms even while permitting the mother to tolerate the semi-allogenic fetus. Trophoblasts, which are fetal-derived placental cells, play a central role on both sides of this duality at the maternal-fetal interface. In brief, the trophoblasts express pattern recognition receptors (PRRs) and are involved in the local innate immune response in the placenta. That response eliminates pathogenic microbes but also causes tissue damage. In this review, we summarize the research findings to date regarding the roles of those human trophoblast PRRs. Multiple types of PRRs (Toll-like receptors, Nod-like receptors, and RIG-I-like receptors) are expressed in the placenta and on trophoblasts. Trophoblasts' PRRs participate in protecting the fetus against viruses, bacteria, and parasites by triggering production of proinflammatory cytokines and chemokines in the placenta. On the negative side, PRR signaling in trophoblasts can also initiate inflammation and trophoblast cell death, which can lead to placental inflammation-associated pregnancy complications such as preeclampsia, anti-phospholipid antibody syndrome, and miscarriage. Further elucidation of these dual roles of trophoblasts' PRRs may shed light on the mechanisms by which fetuses are protected against congenital infections and also give us a better understanding of the etiologies of pregnancy complications, which can help us prevent/reduce adverse prenatal/neonatal outcomes.

A Framework for Understanding Maternal Immunity

This is an alternative and controversial framing of the data relevant to maternal immunity. It argues for a departure from classical theory to view, interrogate and interpret existing data.

Pregnancy imparts distinct systemic adaptive immune function

PROBLEM

Pregnancy represents a state of systemic immune activation that is primarily driven by alterations in circulating innate immune cells. Recent studies have suggested that cellular adaptive immune components, T cells and B cells, also undergo changes throughout gestation. However, the phenotypes and functions of such adaptive immune cells are poorly understood. Herein, we utilized high-dimensional flow cytometry and functional assays to characterize T-cell and B-cell responses in pregnant and non-pregnant women.

METHODS

Peripheral blood mononuclear cells from pregnant (n = 20) and non-pregnant (n = 25) women were used for phenotyping of T-cell and B-cell subsets. T-cell proliferation and B-cell activation were assessed by flow cytometry after in vitro stimulation, and lymphocyte cytotoxicity was evaluated by using a cell-based assay. Statistical comparisons were performed with linear mixed-effects models.

RESULTS

Pregnancy was associated with modestly enhanced basal activation of peripheral CD4+ T cells. Both CD4+ and CD8+ T cells from pregnant women showed increased activation-induced proliferation; yet, a reduced proportion of these cells expressed activation markers compared to non-pregnant women. There were no differences in peripheral lymphocyte cytotoxicity between study groups. A greater proportion of B cells from pregnant women displayed memory-like and activated phenotypes, and such cells exhibited higher activation following stimulation.

CONCLUSION

Maternal circulating T cells and B cells display distinct responses during pregnancy. The former may reflect the unique capacity of T cells to respond to potential threats without undergoing aberrant activation, thereby preventing systemic inflammatory responses that can lead to adverse perinatal consequences.

Immune–Metabolic Interactions and T Cell Tolerance in Pregnancy

Pregnancy depends on a state of maternal immune tolerance mediated by CD4+ regulatory T (Treg) cells. Uterine Treg cells release anti-inflammatory factors, inhibit effector immunity, and support adaptation of the uterine vasculature to facilitate placental development. Insufficient Treg cells or inadequate functional competence is implicated in infertility and recurrent miscarriage, as well as pregnancy complications preeclampsia, fetal growth restriction, and preterm birth, which stem from placental insufficiency. In this review we address an emerging area of interest in pregnancy immunology–the significance of metabolic status in regulating the Treg cell expansion required for maternal–fetal tolerance. We describe how hyperglycemia and insulin resistance affect T cell responses to suppress generation of Treg cells, summarize data that implicate a role for altered glucose metabolism in impaired maternal–fetal tolerance, and explore the prospect of targeting dysregulated metabolism to rebalance the adaptive immune response in women experiencing reproductive disorders.

Severe Acute Respiratory Syndrome Coronavirus 2 Infection Versus Vaccination in Pregnancy: Implications for Maternal and Infant Immunity

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been associated with adverse maternal and neonatal outcomes, yet uptake of SARS-CoV-2 vaccines during pregnancy and lactation has been slow. As a result, millions of pregnant and lactating women and their infants remain susceptible to the virus.

METHODS

We measured spike-specific immunoglobulin G (anti-S IgG) and immunoglobulin A (anti-S IgA) in serum and breastmilk (BM) samples from 3 prospective mother-infant cohorts recruited in 2 academic medical centers. The primary aim was to determine the impact of maternal SARS-CoV-2 immunization vs infection and their timing on systemic and mucosal immunity.

RESULTS

The study included 28 mothers infected with SARS-CoV-2 in late pregnancy (INF), 11 uninfected mothers who received 2 doses of the BNT162b2 vaccine in the latter half of pregnancy (VAX-P), and 12 uninfected mothers who received 2 doses of BNT162b2 during lactation. VAX dyads had significantly higher serum anti-S IgG compared to INF dyads (P < .0001), whereas INF mothers had higher BM:serum anti-S IgA ratios compared to VAX mothers (P = .0001). Median IgG placental transfer ratios were significantly higher in VAX-P compared to INF mothers (P < .0001). There was a significant positive correlation between maternal and neonatal serum anti-S IgG after vaccination (r = 0.68, P = .013), but not infection.

CONCLUSIONS

BNT161b2 vaccination in late pregnancy or lactation enhances systemic immunity through serum anti-S immunoglobulin, while SARS-CoV-2 infection induces mucosal over systemic immunity more efficiently through BM immunoglobulin production. Next-generation vaccines boosting mucosal immunity could provide additional protection to the mother-infant dyad. Future studies should focus on identifying the optimal timing of primary and/or booster maternal vaccination for maximal benefit.

Specific innate immune cells uptake fetal antigen and display homeostatic phenotypes in the maternal circulation

Pregnancy represents a period when the mother undergoes significant immunological changes to promote tolerance of the fetal semi-allograft. Such tolerance results from the exposure of the maternal immune system to fetal antigens (Ags), a process that has been widely investigated at the maternal-fetal interface and in the adjacent draining lymph nodes. However, the peripheral mechanisms of maternal-fetal crosstalk are poorly understood. Herein, we hypothesized that specific innate immune cells interact with fetal Ags in the maternal circulation. To test this hypothesis, a mouse model was utilized in which transgenic male mice expressing the chicken ovalbumin (OVA) Ag under the beta-actin promoter were allogeneically mated with wild-type females to allow for tracking of the fetal Ag. Fetal Ag-carrying Ly6G+ and F4/80+ cells were identified in the maternal circulation, where they were more abundant in the second half of pregnancy. Such innate immune cells displayed unique phenotypes: while Ly6G+ cells expressed high levels of MHC-II and CD80 together with low levels of pro-inflammatory cytokines, F4/80+ cells up-regulated the expression of CD86 as well as the anti-inflammatory cytokines IL-10 and TGF-β. In vitro studies using allogeneic GFP+ placental particles revealed that maternal peripheral Ly6G+ and F4/80+ cells phagocytose fetal Ags in mid and late murine pregnancy. Importantly, cytotrophoblast-derived particles were also engulfed in vitro by CD15+ and CD14+ cells from women in the second and third trimester, providing translational evidence that this process also occurs in humans. Collectively, this study demonstrates novel interactions between specific maternal circulating innate immune cells and fetal Ags, thereby shedding light on the systemic mechanisms of maternal-fetal crosstalk.

Molecular and Physiological Aspects of SARS-CoV-2 Infection in Women and Pregnancy

Whilst scientific knowledge about SARS-CoV-2 and COVID-19 is rapidly increasing, much of the effects on pregnant women is still unknown. To accommodate pregnancy, the human endometrium must undergo a physiological transformation called decidualization. These changes encompass the remodeling of endometrial immune cells leading to immunotolerance of the semi-allogenic conceptus as well as defense against pathogens. The angiotensin converting enzyme 2 (ACE2) plays an important regulatory role in the renin-angiotensin-system (RAS) and has been shown to be protective against comorbidities known to worsen COVID-19 outcomes. Furthermore, ACE2 is also crucial for decidualization and thus for early gestation. An astounding gender difference has been found in COVID-19 with male patients presenting with more severe cases and higher mortality rates. This could be attributed to differences in sex chromosomes, hormone levels and behavior patterns. Despite profound changes in the female body during pregnancy, expectant mothers do not face worse outcomes compared with non-pregnant women. Whereas mother-to-child transmission through respiratory droplets during labor or in the postnatal period is known, another question of in utero transmission remains unanswered. Evidence of placental SARS-CoV-2 infection and expression of viral entry receptors at the maternal-fetal interface suggests the possibility of in utero transmission. SARS-CoV-2 can cause further harm through placental damage, maternal systemic inflammation, and hindered access to health care during the pandemic. More research on the effects of COVID-19 during early pregnancy as well as vaccination and treatment options for gravid patients is urgently needed.

Cellular immune responses in the pathophysiology of preeclampsia

Preeclampsia, defined as new-onset hypertension accompanied by proteinuria occurring at 20 weeks of gestation or later, is a leading cause of perinatal morbidity and mortality worldwide. The pathophysiology of this major multi-systemic syndrome includes defective deep placentation, oxidative stress, endothelial dysfunction, the presence of an anti-angiogenic state, and intravascular inflammation, among others. In this review, we provide a comprehensive overview of the cellular immune responses involved in the pathogenesis of preeclampsia. Specifically, we summarize the role of innate and adaptive immune cells in the maternal circulation, reproductive tissues, and at the maternal-fetal interface of women affected by this pregnancy complication. The major cellular subsets involved in the pathogenesis of preeclampsia are regulatory T cells, effector T cells, NK cells, monocytes, macrophages, and neutrophils. We also summarize the literature on those immune cells that have been less characterized in this clinical condition, such as γδ T cells, invariant natural killer T cells, dendritic cells, mast cells, and B cells. Moreover, we discuss in vivo studies utilizing a variety of animal models of preeclampsia to further support the role of immune cells in this disease. Finally, we highlight the existing gaps in knowledge of the immunobiology of preeclampsia that require further investigation. The goal of this review is to promote translational research leading to clinically relevant strategies that can improve adverse perinatal outcomes resulting from the obstetrical syndrome of preeclampsia.

Placental deficiency during maternal SARS-CoV-2 infection

Introduction

Maternal anti-SARS-CoV-2 Spike antibodies can cross the placenta during pregnancy, and neonates born to infected mothers have acquired antibodies at birth. Few studies reported data on the histopathological changes of the placenta during infection and placental infection. SARS-CoV-2 infection may cause impaired development of the placenta, thus predisposing maternal and fetal unfavorable outcomes. The prospective study aims to evaluate the risk of vertical transmission of SARS-CoV-2 and placental passage of anti-Spike antibodies as well as the impact of clinical severity on placental structures.

Methods

This is a prospective cohort study on 30 pregnant women infected by SARS-CoV-2 with their neonates. The demographic features and pregnancy outcomes were collected. Gross and microscopic examinations of the placentas were done. Maternal and umbilical cord sera were obtained at the time of delivery. Nasopharyngeal swabs were collected from neonates immediately after birth.

Results

The concentrations of total anti-SARS-CoV-2 Spike antibodies were higher in pregnant women with moderate to severe/critical disease. The maternal total anti-SARS-CoV-2 Spike levels were correlated with those of neonatal levels. The rate of placental abnormalities is high in the mothers with severe disease, and those with positive anti-SARS-CoV-2 IgM. All neonates had negative nasopharyngeal swabs for SARS- CoV-2 infections and all placentas were negative in immunohistochemical staining for Spike protein.

Discussion

The maternally derived anti-SARS-CoV-2 Spike antibody can transmit to neonates born to infected mothers regardless of gestational age. Our results indicated that the disease severity is associated with ischemic placental pathology which may result in adverse pregnancy outcomes.

Pharmacological activation of rev-erbα suppresses LPS-induced macrophage M1 polarization and prevents pregnancy loss

BACKGROUND

Circadian rhythm is an important player for reproduction. Rev-erbα, a significant clock gene, is involved in regulating cell differentiation, inflammation and metabolism. Macrophage polarization plays crucial roles in immune tolerance at the maternal-fetus interface, which also modulates the initiation and resolution of inflammation. Alteration of macrophage polarization induces adverse pregnancy outcomes such as infertility, recurrent spontaneous abortion and preterm labor.

RESULTS

Decidual macrophages from LPS-induced mice abortion model displayed M1-like bias, accompanied by decreased expression of Rev-erbα. SR9009, an agonist of Rev-erbα, may reduce lipopolysaccharide (LPS)-induced M1 polarization of macrophages via activation of PI3K but not NF-κB signaling pathway. Furthermore, SR9009 could reduce M1-like polarization of decidual macrophages induced by LPS and attenuate LPS-induced resorption rates in mice model.

CONCLUSIONS

Both in vivo and in vitro experiments demonstrated that the pharmacological activation of Rev-erbα using SR9009 could attenuate the effect of LPS on macrophage polarization and protect pregnancy. This study may provide a potential therapeutic strategy for miscarriage induced by inflammation.

Epidemiology of Pregnancy Complications Through the Lens of Immunological Memory

In the fifteen minutes it takes to read this short commentary, more than 400 babies will have been born too early, another 300 expecting mothers will develop preeclampsia, and 75 unborn third trimester fetuses will have died in utero (stillbirth). Given the lack of meaningful progress in understanding the physiological changes that occur to allow a healthy, full term pregnancy, it is perhaps not surprising that effective therapies against these great obstetrical syndromes that include prematurity, preeclampsia, and stillbirth remain elusive. Meanwhile, pregnancy complications remain the leading cause of infant and childhood mortality under age five. Does it have to be this way? What more can we collectively, as a biomedical community, or individually, as clinicians who care for women and newborn babies at high risk for pregnancy complications, do to protect individuals in these extremely vulnerable developmental windows? The problem of pregnancy complications and neonatal mortality is extraordinarily complex, with multiple unique, but complementary perspectives from scientific, epidemiological and public health viewpoints. Herein, we discuss the epidemiology of pregnancy complications, focusing on how the outcome of prior pregnancy impacts the risk of complication in the next pregnancy — and how the fundamental immunological principle of memory may promote this adaptive response.

Maternal-Fetal Immune Responses in Pregnant Women Infected with SARS-CoV-2

Pregnant women are a high-risk population for severe/critical COVID-19 and mortality. However, the maternal-fetal immune responses initiated by SARS-CoV-2 infection, and whether this virus is detectable in the placenta, are still under investigation. Herein, we report that SARS-CoV-2 infection during pregnancy primarily induced specific maternal inflammatory responses in the circulation and at the maternal-fetal interface, the latter being governed by T cells and macrophages. SARS-CoV-2 infection during pregnancy was also associated with a cytokine response in the fetal circulation (i.e. umbilical cord blood) without compromising the cellular immune repertoire. Moreover, SARS-CoV-2 infection neither altered fetal cellular immune responses in the placenta nor induced elevated cord blood levels of IgM. Importantly, SARS-CoV-2 was not detected in the placental tissues, nor was the sterility of the placenta compromised by maternal viral infection. This study provides insight into the maternal-fetal immune responses triggered by SARS-CoV-2 and further emphasizes the rarity of placental infection.

Impact of COVID-19 on maternal and neonatal outcomes: a systematic review and meta-analysis

BACKGROUND

Previous outbreaks of severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) and Middle East respiratory syndrome coronavirus (MERS-CoV) have been associated with unfavourable pregnancy outcomes. SARS-CoV-2 belongs to the human coronavirus family, and since this infection shows a pandemic trend it will involve many pregnant women.

AIMS

This systematic review and meta-analysis aimed to assess the impact of coronavirus disease 19 (COVID-19) on maternal and neonatal outcomes.

SOURCES

PubMed, EMBASE, MedRxiv, Scholar, Scopus, and Web of Science databases were searched up to 8th May 2020. Articles focusing on pregnancy and perinatal outcomes of COVID-19 were eligible. Participants were pregnant women with COVID-19.

CONTENT

The meta-analysis was conducted following the PRISMA and MOOSE reporting guidelines. Bias risk was assessed using the Joanna Briggs Institute (JBI) manual. The protocol was registered with PROSPERO (CRD42042020184752). Twenty-four articles, including 1100 pregnancies, were selected. The pooled prevalence of pneumonia was 89% (95%CI 70-100), while the prevalence of women admitted to the intensive care unit was 8% (95%CI 1-20). Three stillbirths and five maternal deaths were reported. A pooled prevalence of 85% (95%CI 72-94) was observed for caesarean deliveries. There were three neonatal deaths. The prevalence of COVID-19-related admission to the neonatal intensive care unit was 2% (95%CI 0-6). Nineteen out of 444 neonates were positive for SARS-CoV-2 RNA at birth. Elevated levels of IgM and IgG Serum antibodies were reported in one case, but negative swab.

IMPLICATIONS

Although adverse outcomes such as ICU admission or patient death can occur, the clinical course of COVID-19 in most women is not severe, and the infection does not significantly influence the pregnancy. A high caesarean delivery rate is reported, but there is no clinical evidence supporting this mode of delivery. Indeed, in most cases the disease does not threaten the mother, and vertical transmission has not been clearly demonstrated. Therefore, COVID-19 should not be considered as an indication for elective caesarean section.

The 2016 presidential election and periviable births among Latina women

OBJECTIVE

Research suggests that sociopolitical stressors connected with the 2016 presidential election were associated with increases in preterm birth among Latina women. This study determined whether periviable births (<26 weeks gestation), which exhibit extremely high rates of infant morbidity and mortality, among US Latina women increased above expected levels after the 2016 US presidential election.

METHODS

We assigned singleton live births among Latina and non-Latina white women in the US to 96 monthly conception cohorts conceived from January 2009 through December 2016. We constructed risk ratios by dividing the rate of periviable birth among Latina women by the rate among non-Latina white women. We used time-series methods to determine if the risk ratio of periviable births in cohorts conceived by Latina women and exposed to the election of 2016 exceeded those expected from autocorrelation and calendar effects.

RESULTS

We found an outlying sequence of risk ratios among Latina women starting with the cohort conceived in April and ending with that conceived in November 2016. Increases in the ratios ranged from 0.07 above an expected of 1.61 for the cohort conceived in June, to 0.39 above an expected of 1.27 for the cohort conceived in April.

CONCLUSION

We find that pregnancies in gestation at the time of the 2016 election among Latina women yielded more than expected periviable births. These findings support the argument that the prospect of anti-immigrant policies promised by the Trump campaign sufficiently stressed Latina women to affect the timing of birth.

PlGF Immunological Impact during Pregnancy

During pregnancy, the mother’s immune system has to tolerate the persistence of paternal alloantigens without affecting the anti-infectious immune response. Consequently, several mechanisms aimed at preventing allograft rejection, occur during a pregnancy. In fact, the early stages of pregnancy are characterized by the correct balance between inflammation and immune tolerance, in which proinflammatory cytokines contribute to both the remodeling of tissues and to neo-angiogenesis, thus, favoring the correct embryo implantation. In addition to the creation of a microenvironment able to support both immunological privilege and angiogenesis, the trophoblast invades normal tissues by sharing the same behavior of invasive tumors. Next, the activation of an immunosuppressive phase, characterized by an increase in the number of regulatory T (Treg) cells prevents excessive inflammation and avoids fetal immuno-mediated rejection. When these changes do not occur or occur incompletely, early pregnancy failure follows. All these events are characterized by an increase in different growth factors and cytokines, among which one of the most important is the angiogenic growth factor, namely placental growth factor (PlGF). PlGF is initially isolated from the human placenta. It is upregulated during both pregnancy and inflammation. In this review, we summarize current knowledge on the immunomodulatory effects of PlGF during pregnancy, warranting that both innate and adaptive immune cells properly support the early events of implantation and placental development. Furthermore, we highlight how an alteration of the immune response, associated with PlGF imbalance, can induce a hypertensive state and lead to the pre-eclampsia (PE).

Assessment of Factors Affecting Breastfeeding Performance and Latch Score: A Prospective Cohort Study

OBJECTIVE

To determine the risk factors that may affect LATCH scores.

MATERIALS AND METHODS

We prospectively evaluated the LATCH scores and any relevant risk factors of patients who delivered at our institution during April and May 2020. All examinations were performed by the same physicians during the study period. LATCH scores were determined at initial breastfeeding session, and postnatal days 1 and 2.

RESULTS

We analyzed 338 patients in this prospective study. Patients with high-risk pregnancies were found to have lower LATCH scores at each measurement (p: 0.002, 0.001, and 0.09, respectively). Skin-to-skin contact immediately after delivery and breastfeeding longer than 20 min in the first session did not improve LATCH scores (p>0.05). Breastfeeding within 30 min after delivery significantly improved LATCH scores at each session (p<0.01 for all). Odds ratios of having a LATCH score lower than 8 was 10.9 (95% CI: 4.22-28.37) for the patients breastfed after more than 30 min, while this ratio was 2.17 (95% CI: 1.34-3.50) and 6.5 (95% CI: 3.46-12.58) for the patients having a high-risk pregnancy and cesarean section, respectively. Furthermore, we also determined a positive statistically significant association between parity and all LATCH scores according to regression analyses (p: 0.005, 0.028, and 0.035 for LATCH scores at initial breastfeeding, postnatal day 1 and 2, respectively) CONCLUSION: High-risk pregnancies, patients who delivered by cesarean section, and patients not attempting to breastfeed within 30 min tend to have lower LATCH scores.

Effect of hypocomplementemia on perinatal outcomes of pregnancies with autoimmune disorders

OBJECTIVE

To demonstrate the effect of preconceptional complement levels on perinatal outcomes of pregnancies with autoimmune disorders.

METHODS

Pregnant women with autoimmune disorders (autoimmune disease and/or autoimmune antibody positivity) who were screened for complement levels (C3 and C4) prior to their pregnancies were enrolled in a special antenatal care program. These patients were administered low-dose low-molecular-weight heparin (enoxaparine, 1 × 2000 Anti-XA IU/0.2 mL/day), low-dose salysilic acid (100 mg/day) and low-dose corticosteroid (methylprednisolone, 1 × 4 mg/day orally) as soon as their pregnancies were confirmed according to the institutional protocol. We have compared hypo- and normocomplement pregnancies with autoimmune disorders in terms of their obstetric and perinatal outcomes. We have also used Beksac Obstetric Index (BOI) which is "[living child + (π/10)]/gravidity" for the comparison of their previous obstetric histories.

RESULTS

Obstetric and neonatal outcomes showed no significant difference between hypocomplement patients (n= 38) and control group (n= 157) (p> 0.05). "Composite obstetric and perinatal adverse outcome" rates were 26.2% and 27.3% in study and control groups, respectively (p> 0.05). BOI was significantly lower in hypocomplement patients (p: 0.002). Then, we have classified hypocomplement patients into 3 subgroups according to the type of complement (C3, C4 or both). Comparison inbetween these groups revealed no statistical significance in any of the analyzed parameters (p> 0.05).

CONCLUSION

Low complement levels in pregnant women with autoimmune disorders may be associated with gestational problems and poor obstetric history. Immunomodulatory treatment modalities such as ours may be beneficial for improving the obstetric and neonatal outcomes.

Low plasma levels of decoy receptor 3 (DcR3) in the third trimester of pregnancy with preeclampsia

OBJECTIVE

The pathophysiology of preeclampsia, a major threat during pregnancy characterized by excessive inflammatory status, remains unclear. Decoy receptor 3 (DcR3), a soluble member of the tumor necrosis factor receptor (TNFR) superfamily, is capable of inducing anti-apoptosis via binding with TL1A and anti-inflammation by driving Th2 immune reactions. DcR3 may, therefore, play a role in immune modulation during pregnancy. The purpose of this study is to explore the role of DcR3 in normal and preeclamptic pregnancies.

MATERIALS AND METHODS

Plasma samples from 104 normal pregnant women (26, 42, and 36 in the first, second, and third trimester, respectively) and 10 patients with preeclampsia in the third trimester were collected. Plasma DcR3 levels were determined by using commercial ELISA kits. ANOVA and linear regression analysis were performed to analyze the relationship between gestational age and DcR3 levels. After adjusting for gestational days, the levels of plasma DcR3 in preeclamptic and non-preeclamptic women in the third trimester were compared.

RESULTS

The plasma levels of DcR3 gradually decreased as the gestational days increased during pregnancy (p < 0.05). In the third trimester, pregnant women with preeclampsia had significantly lower plasma DcR3 levels compared to non-preeclamptic women (p < 0.05).

CONCLUSIONS

We found that plasma DcR3 levels gradually decreased as gestation progressed. The levels of plasma DcR3 in preeclamptic women were significantly lower than those of normal pregnant women, suggesting that a potential involvement of DcR3 in normal pregnancy and decreased levels of DcR3 may be related to preeclampsia.

The Cellular Transcriptome in the Maternal Circulation During Normal Pregnancy: A Longitudinal Study

Pregnancy represents a unique immunological state in which the mother adapts to tolerate the semi-allogenic conceptus; yet, the cellular dynamics in the maternal circulation are poorly understood. Using exon-level expression profiling of up to six longitudinal whole blood samples from 49 pregnant women, we undertook a systems biology analysis of the cellular transcriptome dynamics and its correlation with the plasma proteome. We found that: (1) chromosome 14 was the most enriched in transcripts differentially expressed throughout normal pregnancy; (2) the strongest expression changes followed three distinct longitudinal patterns, with genes related to host immune response (e.g., MMP8, DEFA1B, DEFA4, and LTF) showing a steady increase in expression from 10 to 40 weeks of gestation; (3) multiple biological processes and pathways related to immunity and inflammation were modulated during gestation; (4) genes changing with gestation were among those specific to T cells, B cells, CD71+ erythroid cells, natural killer cells, and endothelial cells, as defined based on the GNF Gene Expression Atlas; (5) the average expression of mRNA signatures of T cells, B cells, and erythroid cells followed unique patterns during gestation; (6) the correlation between mRNA and protein abundance was higher for mRNAs that were differentially expressed throughout gestation than for those that were not, and significant mRNA-protein correlations were observed for genes part of the T-cell signature. In summary, unique changes in immune-related genes were discovered by longitudinally assessing the cellular transcriptome in the maternal circulation throughout normal pregnancy, and positive correlations were noted between the cellular transcriptome and plasma proteome for specific genes/proteins. These findings provide insights into the immunobiology of normal pregnancy.

Exhausted and Senescent T Cells at the Maternal-Fetal Interface in Preterm and Term Labor

Successful pregnancy requires a tightly-regulated equilibrium of immune cell interactions at the maternal-fetal interface (i.e., the decidual tissues), which plays a central role in the inflammatory process of labor. Most of the innate immune cells in this compartment have been well characterized; however, adaptive immune cells are still under investigation. Herein, we performed immunophenotyping of the decidua basalis and decidua parietalis to determine whether exhausted and senescent T cells are present at the maternal-fetal interface and whether the presence of pathological (i.e., preterm) or physiological (i.e., term) labor and/or placental inflammation alter such adaptive immune cells. In addition, decidual exhausted T cells were sorted to test their functional status. We found that (1) exhausted and senescent T cells were present at the maternal-fetal interface and predominantly expressed an effector memory phenotype, (2) exhausted CD4⁺ T cells increased in the decidua parietalis as gestational age progressed, (3) exhausted CD4⁺ and CD8⁺ T cells decreased in the decidua basalis of women who underwent labor at term compared to those without labor, (4) exhausted CD4⁺ T cells declined with the presence of placental inflammation in the decidua basalis of women with preterm labor, (5) exhausted CD8⁺ T cells decreased with the presence of placental inflammation in the decidua basalis of women who underwent labor at term, (6) both senescent CD4⁺ and CD8⁺ T cells declined with the presence of placental inflammation in the decidua basalis of women who underwent preterm labor, and (7) decidual exhausted T cells produced IFNγ and TNFα upon in vitro stimulation. Collectively, these findings indicate that exhausted and senescent T cells are present at the human maternal-fetal interface and undergo alterations in a subset of women either with labor at term or preterm labor and placental inflammation. Importantly, decidual T cell function can be restored upon stimulation.

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.

Effector and Activated T Cells Induce Preterm Labor and Birth That Is Prevented by Treatment with Progesterone

Preterm labor commonly precedes preterm birth, the leading cause of perinatal morbidity and mortality worldwide. Most research has focused on establishing a causal link between innate immune activation and pathological inflammation leading to preterm labor and birth. However, the role of maternal effector/activated T cells in the pathogenesis of preterm labor/birth is poorly understood. In this study, we first demonstrated that effector memory and activated maternal T cells expressing granzyme B and perforin are enriched at the maternal-fetal interface (decidua) of women with spontaneous preterm labor. Next, using a murine model, we reported that prior to inducing preterm birth, in vivo T cell activation caused maternal hypothermia, bradycardia, systemic inflammation, cervical dilation, intra-amniotic inflammation, and fetal growth restriction, all of which are clinical signs associated with preterm labor. In vivo T cell activation also induced B cell cytokine responses, a proinflammatory macrophage polarization, and other inflammatory responses at the maternal-fetal interface and myometrium in the absence of an increased influx of neutrophils. Finally, we showed that treatment with progesterone can serve as a strategy to prevent preterm labor/birth and adverse neonatal outcomes by attenuating the proinflammatory responses at the maternal-fetal interface and cervix induced by T cell activation. Collectively, these findings provide mechanistic evidence showing that effector and activated T cells cause pathological inflammation at the maternal-fetal interface, in the mother, and in the fetus, inducing preterm labor and birth and adverse neonatal outcomes. Such adverse effects can be prevented by treatment with progesterone, a clinically approved strategy.

The role of maternal T cell and macrophage activation in preterm birth: Cause or consequence?

The role of the immune system in term (TL) and preterm labor (PTL) is unknown. Despite the fact that globally, PTL remains the most important cause of childhood mortality. Infection, typically of the fetal membranes, termed chorioamnionitis, is the best-understood driver of PTL, but the mechanisms underpinning other causes, including idiopathic and stretch-induced PTL, are unclear, but may well involve activation of the maternal immune system. The final common pathway of placental dysfunction, fetal membrane rupture, cervical dilation and uterine contractions are highly complex processes. At term, choriodecidual rather than myometrial inflammation is thought to drive the onset of labor and similar findings are present in different types of PTL including idiopathic PTL. Although accumulated data has confirmed an association between the immune response and preterm birth, there is yet a need to understand if this response is an initiator or a consequence of tissue-level dysregulation. This review focuses on the potential role of macrophages and T cells in innate and adaptive immunity relevant to preterm birth in humans and animal models.

Spontaneous premature birth as a target of genomic research

Spontaneous preterm birth is a serious and common pregnancy complication associated with hormonal dysregulation, infection, inflammation, immunity, rupture of fetal membranes, stress, bleeding, and uterine distention. Heredity is 25-40% and mostly involves the maternal genome, with contribution of the fetal genome. Significant discoveries of candidate genes by genome-wide studies and confirmation in independent replicate populations serve as signposts for further research. The main task is to define the candidate genes, their roles, localization, regulation, and the associated pathways that influence the onset of human labor. Genomic research has identified some candidate genes that involve growth, differentiation, endocrine function, immunity, and other defense functions. For example, selenocysteine-specific elongation factor (EEFSEC) influences synthesis of selenoproteins. WNT4 regulates decidualization, while a heat-shock protein family A (HSP70) member 1 like, HSPAIL, influences expression of glucocorticoid receptor and WNT4. Programming of pregnancy duration starts before pregnancy and during placentation. Future goals are to understand the interactive regulation of the pathways in order to define the clocks that influence the risk of prematurity and the duration of pregnancy. Premature birth has a great impact on the duration and the quality of life. Intensification of focused research on causes, prediction and prevention of prematurity is justified.

Expression of calcium release-activated and voltage-gated calcium channels genes in peripheral blood mononuclear cells is altered in pregnancy and in type 1 diabetes

Calcium (Ca2+) is an important ion in physiology and is found both outside and inside cells. The intracellular concentration of Ca2+ is tightly regulated as it is an intracellular signal molecule and can affect a variety of cellular processes. In immune cells Ca2+ has been shown to regulate e.g. gene transcription, cytokine secretion, proliferation and migration. Ca2+ can enter the cytoplasm either from intracellular stores or from outside the cells when Ca2+ permeable ion channels in the plasma membrane open. The Ca2+ release-activated (CRAC) channel is the most prominent Ca2+ ion channel in the plasma membrane. It is formed by ORAI1-3 and the channel is opened by the endoplasmic reticulum Ca2+ sensor proteins stromal interaction molecules (STIM) 1 and 2. Another group of Ca2+ channels in the plasma membrane are the voltage-gated Ca2+ (CaV) channels. We examined if a change in immunological tolerance is accompanied by altered ORAI, STIM and CaV gene expression in peripheral blood mononuclear cells (PBMCs) in pregnant women and in type 1 diabetic individuals. Our results show that in pregnancy and type 1 diabetes ORAI1-3 are up-regulated whereas STIM1 and 2 are down-regulated in pregnancy but only STIM2 in type 1 diabetes. Expression of L-, P/Q-, R- and T-type voltage-gated Ca2+ channels was detected in the PBMCs where the CaV2.3 gene was up-regulated in pregnancy and type 1 diabetes whereas the CaV 2.1 and CaV3.2 genes were up-regulated only in pregnancy and the CaV1.3 gene in type 1 diabetes. The results are consistent with that expression of ORAI, STIM and CaV genes correlate with a shift in immunological status of the individual in health, as during pregnancy, and in the autoimmune disease type 1 diabetes. Whether the changes are in general protective or in type 1 diabetes include some pathogenic components remains to be clarified.

Innate Lymphoid Cells in the Maternal and Fetal Compartments

Pregnancy success is orchestrated by the complex balance between the maternal and fetal immune systems. Herein, we summarize the potential role of innate lymphoid cells (ILCs) in the maternal and fetal compartments. We reviewed published literature describing different ILC subsets [ILC1s, ILC2s, ILC3s, and lymphoid tissue inducer (LTi) cells] in the uterus, decidua, fetal tissues [liver, secondary lymphoid organs (SLO), intestine, and lung] and amniotic cavity. ILC1s, ILC2s, and ILC3s are present in the murine uterus prior to and during pregnancy but have only been detected in the non-pregnant endometrium in humans. Specifically, ILC2s reside in the murine uterus from mid-pregnancy to term, ILC1s increase throughout gestation, and ILC3s remain constant. Yet, LTi cells have only been detected in the non-pregnant murine uterus. In the human decidua, ILC1s, ILC3s, and LTi-like cells are more abundant during early gestation, whereas ILC2s increase at the end of pregnancy. Decidual ILC1s were also detected during mid-gestation in mice. Interestingly, functional decidual ILC2s and ILC3s increased in women who underwent spontaneous preterm labor, indicating the involvement of such cells in this pregnancy complication. Fetal ILCs exist in the liver, SLO, intestine, lung, and amniotic cavity. The fetal liver is thought to be the source of ILC progenitors since the differentiation of these cells from hematopoietic stem cells occurs at this site, and mature ILC subsets can be found in this compartment as well. The interaction between LTi cells and specialized stromal cells is important during the formation of SLO. Mature ILCs are found at the mucosal surfaces of the lung and intestine, from where they can extravasate into the amniotic cavity. Amniotic fluid ILCs express high levels of RORγt, CD161, and CD103, hallmarks of ILC3s. Such cells are more abundant in the second trimester than later in gestation. Although amniotic fluid ILC3s produce IL-17A and TNFα, indicating their functionality, their numbers in patients with intra-amniotic infection/inflammation remain unchanged compared to those without this pregnancy complication. Collectively, these findings suggest that maternal (uterine and decidual) ILCs play central roles in both the initiation and maintenance of pregnancy, and fetal ILCs participate in the development of immunity.

Regulatory T cells in embryo implantation and the immune response to pregnancy

At implantation, the embryo expresses paternally derived alloantigens and evokes inflammation that can threaten reproductive success. To ensure a robust placenta and sustainable pregnancy, an active state of maternal immune tolerance mediated by CD4+ regulatory T cells (Tregs) is essential. Tregs operate to inhibit effector immunity, contain inflammation, and support maternal vascular adaptations, thereby facilitating trophoblast invasion and placental access to the maternal blood supply. Insufficient Treg numbers or inadequate functional competence are implicated in idiopathic infertility and recurrent miscarriage as well as later-onset pregnancy complications stemming from placental insufficiency, including preeclampsia and fetal growth restriction. In this Review, we summarize the mechanisms acting in the conception environment to drive the Treg response and discuss prospects for targeting the T cell compartment to alleviate immune-based reproductive disorders.

Locally advanced cervical cancer complicating pregnancy: A case of competing risks from the Catholic University of the Sacred Heart in Rome

A case of stage IB2 cervical cancer at 27 weeks of pregnancy, treated with neoadjuvant chemotherapy followed by radical Cesarean hysterectomy with full pelvic and infra-mesenteric lymphadenectomy, and adjuvant chemo-radiation is described. While she remains without disease, her baby was diagnosed with acute myelogenous leukemia. We highlight the pre-operative work-up, treatment options, safety, feasibility, and outcomes for the mother and her fetus.

Extracellular vesicles generated by placental tissues ex vivo: A transport system for immune mediators and growth factors

PROBLEM

To study the mechanisms of placenta function and the role of extracellular vesicles (EVs) in pregnancy, it is necessary to develop an ex vivo system that retains placental cytoarchitecture and the primary metabolic aspects, in particular the release of EVs and soluble factors. Here, we developed such a system and investigated the pattern of secretion of cytokines, growth factors, and extracellular vesicles by placental villous and amnion tissues ex vivo.

METHODS OF STUDY

Placental villous and amnion explants were cultured for 2 weeks at the air/liquid interface and their morphology and the released cytokines and EVs were analyzed. Cytokines were analyzed with multiplexed bead assays, and individual EVs were analyzed with recently developed techniques that involved EV capture with magnetic nanoparticles coupled to anti-EV antibodies and flow cytometry.

RESULTS

Ex vivo tissues (i) remained viable and preserved their cytoarchitecture; (ii) maintained secretion of cytokines and growth factors; (iii) released EVs of syncytiotrophoblast and amnion epithelial cell origins that contain cytokines and growth factors.

CONCLUSION

A system of ex vivo placental villous and amnion tissues can be used as an adequate model to study placenta metabolic activity in normal and complicated pregnancies, in particular to characterize EVs by their surface markers and by encapsulated proteins. Establishment and benchmarking the placenta ex vivo system may provide new insight in the functional status of this organ in various placental disorders, particularly regarding the release of EVs and cytokines. Such EVs may have a prognostic value for pregnancy complications.