Pro-inflammatory cytokine-stimulated first trimester decidual cells enhance macrophage-induced apoptosis of extravillous trophoblasts

Circulating inflammatory cytokines and hypertensive disorders of pregnancy: a two-sample Mendelian randomization study

Background

Hypertensive disorders of pregnancy (HDP) pose a significant risk to maternal and fetal well-being; however, the etiology and pathogenesis of HDP remain ambiguous. It is now widely acknowledged that inflammatory response and the immune system are closely related to HDP. Previous research has identified several inflammatory cytokines are associated with HDP. This study applied Mendelian randomization (MR) analysis to further assess causality.

Methods

Patients with HDP who participated in the MR analysis presented with four types of HDP: pre-eclampsia or eclampsia (PE); gestational hypertension (GH); pre-existing hypertension complicating pregnancy, childbirth and the puerperium (EH); and pre-eclampsia or poor fetal growth (PF). A two-sample MR analysis was used to analyze the data in the study. The causal relationship between exposure and outcome was analyzed with inverse variance weighting (IVW), MR Egger, weighted median, weighted mode, and simple mode methods, where IVW was the primary method employed.

Results

Our MR analysis demonstrated a reliable causative effect of Interleukin-9 (IL-9) and macrophage migration inhibitory factor (MIF) on reducing HDP risk, while macrophage inflammatory protein 1-beta (MIP1b), Interleukin-13 (IL-13), and Interleukin-16 (IL-16) were associated with promoting HDP risk.

Conclusions

This study demonstrated that IL-9, MIF, MIP1b, IL-13, and IL-16 may be cytokines associated with the etiology of HDP, and that a number of inflammatory cytokines are probably involved in the progression of HDP. Additionally, our study revealed that these inflammatory cytokines have causal associations with HDP and may likely be potential therapeutic targets for HDP.

The Molecular Mechanisms of HLA-G Regulatory Function on Immune Cells during Early Pregnancy

Human leukocyte antigen-G (HLA-G) is a non-classical human major histocompatibility complex (MHC-I) molecule with the membrane-bound and soluble types. HLA-G is primarily expressed by extravillous cytotrophoblast cells located at the maternal-fetal interface during pregnancy and is essential in establishing immune tolerance. This review provides a comprehensive understanding of the multiple molecular mechanisms by which HLA-G regulates the immune function of NK cells. It highlights that HLA-G binds to microRNA to suppress NK cell cytotoxicity and stimulate the secretion of growth factors to support fetal growth. The interactions between HLA-G and NK cells also activate senescence signaling, promoting spiral artery remodeling and maintaining the balance of maternal-fetal immune responses. In addition, HLA-G can inhibit the function of decidual T cells, dendritic cells, and macrophages. Overall, the interaction between trophoblast cells and immune cells mediated by HLA-G plays a crucial role in understanding immune regulation at the maternal-fetal interface and offers insights into potential treatments for pregnancy-related diseases.

Colnoy-stimulating factor 1 positive (CSF1+ ) secretory epithelial cells induce excessive trophoblast invasion in tubal pregnancy rupture

Tubal ectopic pregnancy (TEP) occurs when an embryo aberrantly implants in the fallopian tube, leading to abortive or ruptured tubal ectopic pregnancy (AEP or REP). Poor outcomes of REP include maternal infertility or mortality. Current studies on the prevention and treatment of ruptured tubal ectopic pregnancy (REP) are unfortunately hampered by a lack of the cell spectrum and cell-cell communications in the maternal-foetal interface. Here, we investigate the mechanisms of tubal rupture through single-cell transcriptome profiling of the fallopian tube-trophoblast interface in REP, AEP and intrauterine pregnancy patients. In REP, extravillous trophoblast (EVTs) cells form a dominant cell population, displaying aggressive invasion and proliferation, with robust differentiation into three subsets. Cell communication analysis identified colony-stimulating factor 1 (CSF1), overexpressed by fallopian tube secretory epithelial cells in REP, with CSF1R on EVTs and macrophages, as a ligand/receptor pair that stimulates EVT invasion and macrophage accumulation. CSF1+ secretory epithelial cells stimulate EVTs migration and invasion, leading to a tubal rupture in REP. These results provide a mechanistic context and cellular milieu leading to tubal rupture, facilitating further study and development of therapeutics for REP in early pregnancy.

The imbalance of circulating monocyte subgroups with a higher proportion of the CD14+CD16+CD163+ phenotype in patients with preeclampsia

BACKGROUND

Preeclampsia is a major cause of increased maternal and fetal morbidity and mortality, which is closely related to the abnormal maternal immune response. The skew of decidual macrophage polarization toward M1 phenotype has been proved to promote the pathogenesis of preeclampsia. However, it's not easy to monitor the change of decidual macrophage subtypes. The current study aims to examine the distribution of different circulating monocyte subtypes and analyze whether certain monocyte subtypes act as potential clinical indicators for preeclampsia.

METHODS

A total of 50 pregnant women [mild preeclampsia (n = 20); severe preeclampsia (n = 15); healthy pregnancy (n = 15)] and 15 healthy donors were included in the study. Medical information such as BMI, blood pressure, ALT, creatinine, thrombocyte, etc., were recorded. The frequency of different monocyte subtypes in venous blood were measured by flow cytometry. Serum level of IL-6 was detected using Roche-Hitachi cobas 8000. Serum concentration of inflammatory cytokines (IL-1β, IL-4, IL-10 and TNF-α) were measured by ELISA.

RESULTS

A circulating monocyte subset with both M1 and M2 markers (CD14+CD16+CD163+) was found to occupy an obvious higher proportion in the preeclampsia group than in the normal pregnancy group. The ratio of CD206+/CD206- M2-like monocytes was also increased in the preeclampsia group, and meanwhile, it had statistic difference between the mild- and the severe-preeclampsia group. Furthermore, the serum levels of IL-1β and TNF-α were positively correlated with the frequency of CD14+CD16+CD163+ intermediate monocytes in the preeclampsia group.

CONCLUSIONS

The increased proportion of CD14+C16+CD163+ circulating monocytes and the high ratio of CD206+/CD206- M2-like monocytes may act as potential clinical indicators for preeclampsia, with the superiority of convenience and dynamic monitoring.

Decidual macrophages in recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) is defined as two or more pregnancy loss, affecting the happiness index of fertility couples. The mechanisms involved in the occurrence of RSA are not clear to date. The primary problem for the maternal immune system is how to establish and maintain the immune tolerance to the semi-allogeneic fetuses. During the pregnancy, decidual macrophages mainly play an important role in the immunologic dialogue. The purpose of this study is to explore decidual macrophages, and to understand whether there is a connection between these cells and RSA by analyzing their phenotypes and functions. Pubmed, Web of Science and Embase were searched. The eligibility criterion for this review was evaluating the literature about the pregnancy and macrophages. Any disagreement between the authors was resolved upon discussion and if required by the judgment of the corresponding author. We summarized the latest views on the phenotype, function and dysfunction of decidual macrophages to illuminate its relationship with RSA.

Mast Cell Activation Syndrome in COVID-19 and Female Reproductive Function: Theoretical Background vs. Accumulating Clinical Evidence

Coronavirus disease 2019 (COVID-19), a pandemic disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, can affect almost all systems and organs of the human body, including those responsible for reproductive function in women. The multisystem inflammatory response in COVID-19 shows many analogies with mast cell activation syndrome (MCAS), and MCAS may be an important component in the course of COVID-19. Of note, the female sex hormones estradiol (E2) and progesterone (P4) significantly influence mast cell (MC) behavior. This review presents the importance of MCs and the mediators from their granules in the female reproductive system, including pregnancy, and discusses the mechanism of potential disorders related to MCAS. Then, the available data on COVID-19 in the context of hormonal disorders, the course of endometriosis, female fertility, and the course of pregnancy were compiled to verify intuitively predicted threats. Surprisingly, although COVID-19 hyperinflammation and post-COVID-19 illness may be rooted in MCAS, the available clinical data do not provide grounds for treating this mechanism as significantly increasing the risk of abnormal female reproductive function, including pregnancy. Further studies in the context of post COVID-19 condition (long COVID), where inflammation and a procoagulative state resemble many aspects of MCAS, are needed.

Circulating extracellular vesicles exhibit a differential miRNA profile in gestational diabetes mellitus pregnancies

We undertook a prospective temporal study collecting blood samples from consenting pregnant women, to test the hypothesis that circulating extracellular vesicles (EVs) carrying specific non-coding microRNA signatures can underlie gestational diabetes mellitus (GDM). To test this hypothesis, miRNA cargo of isolated and characterized EVs revealed contributions from the placenta and differential expression at all three trimesters and at delivery between pregnant and non-pregnant states. Many miRNAs originate from the placental-specific chromosome 19 microRNA cluster (19MC) and chromosome 14 microRNA cluster (14MC). Further a positive correlation emerged between third trimester and at delivery EVs containing miRNAs and those expressed by the corresponding post-parturient placentas (R value = 0.63 to 0.69, p value = 2.2X10-16), in normal and GDM. In addition, distinct differences at all trimesters emerged between women who subsequently developed GDM. Analysis by logistic regression with leave-one-out-cross validation revealed the optimal combination of miRNAs using all the circulating miRNAs (miR-92a-3p, miR-192-5p, miR-451a, miR-122-5p), or using only the differentially expressed miRNAs (has-miR-92a-3p, hsa-miR-92b-3p, hsa-miR-100-5p and hsa-miR-125a-3p) in GDM during the first trimester. As an initial step, both sets of miRNAs demonstrated a predictive probability with an area under the curve of 0.95 to 0.96. These miRNAs targeted genes involved in cell metabolism, proliferation and immune tolerance. In particular genes of the P-I-3-Kinase, FOXO, insulin signaling and glucogenic pathways were targeted, suggestive of placental connectivity with various maternal organs/cells, altering physiology along with pathogenic mechanisms underlying the subsequent development of GDM. We conclude that circulating EVs originating from the placenta with their miRNA cargo communicate and regulate signaling pathways in maternal organs, thereby predetermining development of GDM.

Obstetric Antiphospholipid Syndrome From the Perspective of a Rheumatologist

Antiphospholipid syndrome (APS) is an autoimmune disease that can lead to thrombotic or obstetric complications. Recent histopathological studies have shown the absence of placental thrombosis, leading to the consideration of other pathophysiological pathways such as inflammation and complement activation. Due to this, various clinical studies are being carried out with different drug agents in order to avoid their complications. The combination of prophylactic heparin treatment and low doses of aspirin today result in successful pregnancies in most cases. Despite this, a minority of patients require alternative therapies to avoid recurrent miscarriage and decrease obstetric morbidity. Thanks to the better understanding of its pathophysiology, other treatments such as low doses of glucocorticoids, hydroxychloroquine (HCQ), immunoglobulin, pravastatin, and plasmapheresis have been considered in refractory cases, achieving favorable results. Despite the great advances regarding its treatment, unfortunately, there are no treatments with a good level of evidence to reduce late obstetric complications. The evaluation of preconception risk factors, as well as the antiphospholipid antibody profile, is necessary to establish individual risk and thus anticipate possible complications.

Crosstalk Between Trophoblast and Macrophage at the Maternal-Fetal Interface: Current Status and Future Perspectives

The immune tolerance microenvironment is crucial for the establishment and maintenance of pregnancy at the maternal-fetal interface. The maternal-fetal interface is a complex system containing various cells, including lymphocytes, decidual stromal cells, and trophoblasts. Macrophages are the second-largest leukocytes at the maternal-fetal interface, which has been demonstrated to play essential roles in remodeling spiral arteries, maintaining maternal-fetal immune tolerance, and regulating trophoblast's biological behaviors. Many researchers, including us, have conducted a series of studies on the crosstalk between macrophages and trophoblasts at the maternal-fetal interface: on the one hand, macrophages can affect the invasion and migration of trophoblasts; on the other hand, trophoblasts can regulate macrophage polarization and influence the state of the maternal-fetal immune microenvironment. In this review, we systemically introduce the functions of macrophages and trophoblasts and the cell-cell interaction between them for the establishment and maintenance of pregnancy. Advances in this area will further accelerate the basic research and clinical translation of reproductive medicine.

BEWO trophoblast cells and Toxoplasma gondii infection modulate cell death mechanisms in THP-1 monocyte cells by interference in the expression of death receptor and intracellular proteins

Crosstalk between trophoblast and monocytes is essential for gestational success, and it can be compromised in congenital toxoplasmosis. Cell death is one of the mechanisms involved in the maintenance of pregnancy, and this study aimed to evaluate the role of trophoblast in the modulation of monocyte cell death in the presence or absence of Toxoplasma gondii infection. THP-1 cells were stimulated with supernatants of BeWo cells and then infected or not with T. gondii. The supernatants were collected and analyzed for the secretion of human Fas ligand, and cells were used to determine cell death and apoptosis, cell death receptor, and intracellular proteins expression. Cell death and apoptosis index were higher in uninfected THP-1 cells stimulated with supernatants of BeWo cells; however, apoptosis index was reduced by T. gondii infection. Macrophage migration inhibitory factor (MIF) and transforming growth factor (TGF)-β1, secreted by BeWo cells, altered the cell death and apoptosis rates in THP-1 cells. In infected THP-1 cells, the expression of Fas/CD95 and secretion of FasL was significantly higher; however, caspase 3 and phosphorylated extracellular-signal-regulated kinase (ERK1/2) were downregulated. Results suggest that soluble factors secreted by BeWo cells induce cell death and apoptosis in THP-1 cells, and Fas/CD95 can be involved in this process. On the other hand, T. gondii interferes in the mechanism of cell death and inhibits THP-1 cell apoptosis, which can be associated with active caspase 3 and phosphorylated ERK1/2. In conclusion, our results showed that human BeWo trophoblast cells and T. gondii infection modulate cell death in human THP-1 monocyte cells.

Obstetric anti-phospholipid syndrome: from pathogenesis to treatment

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by clinical manifestations such as thrombosis and obstetric complications with documented persistence of antiphospholipid antibodies (aPLs). Recent studies have revealed that the cause of aPL-related obstetric complications is dysfunction of placental trophoblasts and inflammation of the maternal-fetal interface induced by aPLs, not thrombosis. Although aPLs are associated with recurrence of serious complications during pregnancy, appropriate combination therapy with heparin and low-dose aspirin can improve the course of 70-80% of subsequent pregnancies. Preconception counseling and patient-tailored treatment are fundamental to improving maternal and fetal outcomes. Non-anticoagulant treatments such as hydroxychloroquine and statins are being developed for cases refractory to conventional treatment. Risk factors for thrombosis after pregnancy complications were identified based on the analysis of large databases of obstetric APS.

Pathogenesis of uteroplacental acute atherosis: An update on current research

Uteroplacental acute atherosis is a type of arterial vascular disease that affects the placenta during pregnancy and predominates in the maternal spiral arteries in the decidua basalis layer of the pregnant uterus. This condition is characterized by fibrin-like necrosis of the blood vessel walls, the accumulation of macrophages containing fat (foam cells), and the infiltration of macrophages around blood vessels. Uteroplacental acute atherosis is rare in normal pregnancy but occurs more frequently in patients with pregnancy complications, including preeclampsia, spontaneous preterm labor, preterm prelabor rupture of membranes, mid-trimester spontaneous abortion, fetal death, and small-for-gestational age. It is believed that the mechanisms underlying the development of uteroplacental acute atherosis are related to the incomplete physiological transformation of spiral arteries, placental inflammation, abnormal lipid metabolism, and oxidative stress. In this review, we describe the pathogenesis of uteroplacental acute atherosis to provide reference guidelines for the future prevention and treatment of uteroplacental acute atherosclerotic disease.

Progesterone and vitamin D downregulate the activation of the NLRP1/NLRP3 inflammasomes and TLR4-MyD88-NF-κB pathway in monocytes from pregnant women with preeclampsia

This study evaluated the in vitro modulatory effect of progesterone (PG) and vitamin D (VD) on NLRP1/NLRP3 inflammasomes and TLR4/NF-κB pathway in monocytes from pregnant women with preeclampsia (PE). Monocytes from 20 preeclamptic and 20 normotensive (NT) pregnant women, and THP-1 cells were cultured with/without hyaluronan (HA), PG, or VD to determine gene and protein expression of TLR4 receptor, phosphorylated NF-κB, IκBα, TLR4, MYD88, NF-κB, NLRP1, NLRP3, caspase-1, IL-1β, IL-18, TNF-α, and IL-10. Higher endogenous activation of inflammatory genes and higher protein expression of TLR4 and NF-κB was detected in monocytes of PE group and decreased after PG or VD treatment. Monocyte from PE stimulated with HA increased while treatment with PG or VD decreased the expression of genes and proteins related to the inflammasomes. THP-1 cells showed a similar immune response profile as monocytes from PE. These results demonstrate that PG and VD play an immunomodulatory role in monocyte activation.

Functional regulation of decidual macrophages during pregnancy

A successful pregnancy requires that the maternal immune system recognizes and tolerates the semi-allogeneic fetus without compromising the capability of protecting both mother and fetus from various pathogens. Decidual macrophages present unique phenotypes to play a key role in the establishment of the immunological aspects of maternal-fetal interaction. Dysfunction of decidual macrophages gives rise to pregnancy complications such as preeclampsia, recurrent spontaneous miscarriage, preterm labor and fetal growth restriction. Here, we reviewed the latest knowledge on the origin, differentiation, unique phenotype and function of macrophages in normal pregnancy and in pregnancy complications. We mainly focused on the significant roles of decidual macrophages in the process of extravillous trophoblast invasion, spiral arterial remodeling, decidual stromal cells cultivation and immune tolerance maintenance in normal pregnancy, and their pathological roles in pregnancy-related complications, offering more integrated information in maternal-fetal immunity.

Silibinin induces in vitro M2-like phenotype polarization in monocytes from preeclamptic women

Preeclampsia (PE) is a pregnancy-specific syndrome featuring intense activation of circulating monocytes and an imbalance between pro- and anti-inflammatory cytokines. The present study evaluated the immunomodulatory effect of silibinin (Sb) on the expression of surface markers and the nuclear transcription factor NF-κB signalling pathway of monocytes from preeclamptic women. Monocytes were cultured with or without Sb, and the mean fluorescence intensity of the surface molecules TLR4, CD64, and CD163 as well as the intracellular transcription factors IκB-α and NF-κBp65 was analysed by flow cytometry. The concentration of cytokines in the monocyte culture supernatant was determined by cytometric bead array and ELISA immunoassay. The results showed that the in vitro treatment of monocytes from preeclamptic women with Sb downregulated the endogenous activation of NF-κB and the expression of surface receptors TLR4 and CD64, and reduced the synthesis of the pro-inflammatory cytokines interleukin 1 (IL-1β), IL-6, IL-8, IL-12p70, IL-23, and tumour necrosis factor alpha (TNF-α) compared with cultures not treated with Sb. The presence of this flavonoid in monocyte cultures increased the expression of CD163 and IκBα and the release of IL-10 and transforming growth factor beta (TGF-β) in the culture supernatants, polarising these cells from the M1-like profile to the M2-like profile. The anti-inflammatory activity of Sb on the NF-κB activation pathway and induction of cell polarisation to the M2 profile was confirmed by an in vitro assay using monocytes from healthy, non-pregnant women. Treatment of monocytes from preeclamptic women with Sb polarises the cells to the M2-like phenotype, suggesting that this flavonoid has an immunomodulatory effect on the sterile inflammation characteristic of PE.

Maternal Obesity and the Uterine Immune Cell Landscape: The Shaping Role of Inflammation

Inflammation is often equated to the physiological response to injury or infection. Inflammatory responses defined by cytokine storms control cellular mechanisms that can either resolve quickly (i.e., acute inflammation) or remain prolonged and unabated (i.e., chronic inflammation). Perhaps less well-appreciated is the importance of inflammatory processes central to healthy pregnancy, including implantation, early stages of placentation, and parturition. Pregnancy juxtaposed with disease can lead to the perpetuation of aberrant inflammation that likely contributes to or potentiates maternal morbidity and poor fetal outcome. Maternal obesity, a prevalent condition within women of reproductive age, associates with increased risk of developing multiple pregnancy disorders. Importantly, chronic low-grade inflammation is thought to underlie the development of obesity-related obstetric and perinatal complications. While diverse subsets of uterine immune cells play central roles in initiating and maintaining healthy pregnancy, uterine leukocyte dysfunction as a result of maternal obesity may underpin the development of pregnancy disorders. In this review we discuss the current knowledge related to the impact of maternal obesity and obesity-associated inflammation on uterine immune cell function, utero-placental establishment, and pregnancy health.

C-reactive protein, interleukin-6 and pre-eclampsia: large-scale evidence from the GenPE case-control study

Multiple small studies have suggested that women with pre-eclampsia present elevated levels of C-reactive protein (CRP) and interleukin-6 (IL-6). However, little is known regarding the source of this CRP and IL-6 increase. Therefore, the aim of this study was to evaluate the relationship between CRP and IL-6 levels with pre-eclampsia considering different confounding factors. Using data from a large Colombian case-control study (3,590 cases of pre-eclampsia and 4,564 normotensive controls), CRP and IL-6 levels were measured in 914 cases and 1297 controls. The association between maternal serum levels of CRP and IL-6 with pre-eclampsia risk was evaluated using adjusted logistic regression models. Pre-eclampsia was defined as presence of blood pressure ≥140/90 mmHg and proteinuria ≥300mg/24 h (or ≥1 + dipstick). There was no evidence of association between high levels of CRP and IL-6 with pre-eclampsia after adjusting for the following factors: maternal and gestational age, ethnicity, place and year of recruitment, multiple-pregnancy, socio-economic position, smoking, and presence of infections during pregnancy. The adjusted OR for 1SD increase in log-CRP and log-IL-6 was 0.96 (95%CI 0.85, 1.08) and 1.09 (95%CI 0.97, 1.22), respectively. Although previous reports have suggested an association between high CRP and IL-6 levels with pre-eclampsia, sample size may lack the sufficient power to draw robust conclusions, and this association is likely to be explained by unaccounted biases. Our results, the largest case-control study reported up to date, demonstrate that there is not a causal association between elevated levels of CRP and IL-6 and the presence of pre-eclampsia.

Leukemia inhibitory factor regulates the activation of inflammatory signals in macrophages and trophoblast cells

The pleiotropic cytokine leukemia inhibitory factor (LIF) is a key gestational factor known to establish dynamic cellular and molecular cross talk at the feto-maternal interface. Previously, we described the regulatory role of the LIF-trophoblast-IL10 axis in the process of macrophage deactivation in response to pro-inflammatory cytokines. However, the direct regulatory effects of LIF in macrophage and trophoblast cell function remains elusive. In this study, we aimed to examine whether and how LIF regulates the behavior of macrophages and trophoblast cells in response to pro-inflammatory stress factors. We found that LIF modulated the activating effects of interferon-gamma (IFNγ) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in macrophages and trophoblast cells by reducing the phosphorylation levels of signal transducer and activator of transcription-1 (Stat1) and -5 (Stat5). Cell activation with IFNγ inhibited cell invasion and migration but this immobilizing effect was abrogated when macrophages and trophoblast cells were deactivated with LIF; macrophage cell motility restitution could in part be explained by the positive effects of LIF in Stat3 activation and matrix metalloproteinase 9 (MMP-9) expression. Pharmacological inhibition of Stat1 and Stat3 indicated that IFNγ-induced Stat1 activation mediated macrophage motility inhibition, and that cell motility in IFNγ-activated macrophages is restored via LIF-induced Stat3 activation and Stat1 inhibition. Moreover, IFNγ-induced TNFα gene expression was also abrogated by LIF through Stat1 inhibition and Stat3 activation. Finally, we have found that cell invasion of trophoblast cells is inhibited when they were cocultured with GM-CSF-differentiated, IFNγ-stimulated macrophages. This effect, however, was inhibited when macrophages were exposed to LIF. Overall, this in vitro study reveals for the first time the anti-inflammatory and pro-gestational activities of LIF by acting directly on macrophages and trophoblast cells.

Role of Macrophages in Pregnancy and Related Complications

Macrophages (MФs) are the leukocytes produced from differentiation of monocytes and are located in almost all tissues of human body. They are involved in various processes, such as phagocytosis, innate and adaptive immunity, proinflammatory (M1) and anti-inflammatory (M2) activity, depending on the tissue microenvironment. They play a crucial role in pregnancy, and their dysfunction or alteration of polarity is involved in pregnancy disorders, like preeclampsia, recurrent spontaneous abortion, infertility, intrauterine growth restriction, and preterm labor. About 50-60% of decidual leukocytes are natural killer (NK) cells followed by MФs (the second largest population). MФs are actively involved in trophoblast invasion, tissue and vascular remodeling during early pregnancy, besides their role as major antigen-presenting cells in the decidua. These cells have different phenotypes and polarities in different stages of pregnancy. They have also been observed to enhance tumor growth by their anti-inflammatory activity (M2 type) and prevent immunogenic rejection. Targeted alteration of polarity (M1-M2 or vice versa) could be a major focus in the future treatment of pregnancy complications. This review is focused on the role of MФs in pregnancy, their involvement in pregnancy disorders, and decidual MФs as possible therapeutic targets for the treatment of pregnancy complications.

Regulation of CX3CL1 Expression in Human First-Trimester Decidual Cells: Implications for Preeclampsia

C-X3-C motif ligand 1 (CX3CL1) mediates migration, survival, and adhesion of natural killer (NK) cells, monocytes, and T-cells to endothelial/epithelial cells. Aberrant numbers and/or activation of these decidual immune cells elicit preeclampsia development. Decidual macrophages and NK cells are critical for implantation, while macrophage-derived tumor necrosis factor-α (TNF-α), interleukin-1 β (IL-1β), and NK cell-derived interferon-γ (IFN-γ) are associated with preeclampsia development. Thus, serum and decidual levels of CX3CL1 from first-trimester pregnancy and preeclampsia-complicated term pregnancy were examined by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry, respectively. The effects of incubating primary human first-trimester decidual cells (FTDCs) with estradiol + medroxyprogesterone acetate + either IL-1β or TNF-α and/or IFN-γ on CX3CL1 expression were also assessed by quantitative reverse transcription-polymerase chain reaction and ELISA. The inhibition of each signaling pathway with each kinase and nuclear factor κB (NFκB) inhibitors was evaluated by ELISA. Chemotaxis of CD56brightCD16- NK cells by various concentrations of CX3CL1 was evaluated. C-X3-C motif ligand 1 is expressed by both cytotrophoblasts and decidual cells in first-trimester decidua. C-X3-C motif ligand 1 expression is increased in term decidua but unchanged in first-trimester and term serum of patients with preeclampsia. Interferon-gamma and either IL-1β or TNF-α synergistically upregulated CX3CL1 expression in FTDCs. Coincubation with IL-1β or TNF-α or IFN-γ, mitogen-activated protein kinase kinase 1 and 2 (MEK1/2), c-JUN N-terminal kinase (JNK), and NFκB inhibitors suppressed CX3CL1 production. C-X3-C motif ligand 1 elicited concentration-dependent enhancement of CD56brightCD16- NK cell migration. In conclusion, the current study suggests that decidual cell-secreted CX3CL1 is involved in the later development of preeclampsia, whereas circulating CX3CL1 levels do not predict preeclampsia. Mitogen-activated protein kinase kinase 1 and 2, JNK, and NFκB signaling mediate IL-1β-, TNF-α-, and IFN-γ-induced CX3CL1 production by FTDCs.

Macrophage Polarization in Physiological and Pathological Pregnancy

The immunology of pregnancy is complex and poorly defined. During the complex process of pregnancy, macrophages secrete many cytokines/chemokines and play pivotal roles in the maintenance of maternal-fetal tolerance. Here, we summarized the current knowledge of macrophage polarization and the mechanisms involved in physiological or pathological pregnancy processes, including miscarriage, preeclampsia, and preterm birth. Although current evidence provides a compelling argument that macrophages are important in pregnancy, our understanding of the roles and mechanisms of macrophages in pregnancy is still rudimentary. Since macrophages exhibit functional plasticity, they may be ideal targets for therapeutic manipulation during pathological pregnancy. Additional studies are needed to better define the functions and mechanisms of various macrophage subsets in both normal and pathological pregnancy.

Alteration of the immune cell profiles in the pathophysiology of tubal ectopic pregnancy

Tubal ectopic pregnancy (TEP) refers to implantation of conceptus in the fallopian tube. It makes up over 98% of ectopic pregnancy (EP), which is the leading cause of maternal morbidity and mortality in the first trimester of pregnancy. Immune cells at the maternal-fetal interface play important roles in the process of embryo implantation, stroma decidualization, and early placental development. Alterations in the composition, phenotype, and activity of the immune cells in the fallopian tubes contribute toward the onset of TEP. In this review, we compare the leukocytic proportions in decidua of normal pregnancy, and in decidua and fallopian tubes of TEP. The possible functions of these immune cells in the pathophysiology of TEP are also discussed.

Antibodies: The major participants in maternal-fetal interaction

The aim of this study is to improve our understanding of the mechanisms involved in maternal-fetal immune tolerance. We searched the related literatures and overviewed the major antibodies associated with pregnancy and described in details their possible roles in mediating maternal-fetal interactions. Antibodies classified into different types based on their functional or structural characteristics were summarized, including immunoglobulin G, blocking antibody, nonprecipitating asymmetric antibody, antiphospholipid antibody, antitrophoblast antibody and antipaternal antibody. The presence and levels of various circulating antibodies in pregnancy may play a crucial role in the occurrence, development and termination of pregnancy.

Human extravillous trophoblast invasion: intrinsic and extrinsic regulation

During the establishment of pregnancy, a human blastocyst implants into the uterine endometrium to facilitate the formation of a functional placenta. Implantation involves the blastocyst adhering to the uterine luminal epithelium before the primitive syncytiotrophoblast and subsequently specialised cells, the extravillous trophoblast (EVT), invade into the decidua in order to engraft and remodel uterine spiral arteries, creating the placental blood supply at the end of the first trimester. Defects in EVT invasion lead to abnormal placentation and thus adverse pregnancy outcomes. The local decidual environment is thought to play a key role in regulating trophoblast invasion. Here we describe the major cell types present in the decidua during the first trimester of pregnancy and review what is known about their regulation of EVT invasion. Overall, the evidence suggests that in a healthy pregnancy almost all cell types in the decidua actively promote EVT invasion and, further, that reduced EVT invasion towards the end of the first trimester is regulated, in part, by the reduced invasive capacity of EVTs shown at this time.

Maternal choline supplementation during murine pregnancy modulates placental markers of inflammation, apoptosis and vascularization in a fetal sex-dependent manner

INTRODUCTION

Normal placental vascular development is influenced by inflammatory, angiogenic and apoptotic processes, which may be modulated by choline through its role in membrane biosynthesis, cellular signaling and gene expression regulation. The current study examined the effect of maternal choline supplementation (MCS) on placental inflammatory, angiogenic and apoptotic processes during murine pregnancy.

METHOD

Pregnant dams were randomized to receive 1, 2 or 4 times (X) the normal choline content of rodent diets, and tissues were harvested on embryonic day (E) 10.5, 12.5, 15.5 or 18.5 for gene expression, protein abundance and immunohistochemical analyses.

RESULTS

The choline-induced changes in the inflammatory and angiogenic markers were a function of fetal sex. Specifically, 4X (versus 1X) choline reduced the transcript (P ≤ 0.05) and protein (P ≤ 0.06) expression of TNF-a and IL-1β in the male placentas at E10.5 and E18.5, respectively. In the female placentas, 4X (versus 1X) choline modulated the transcript expression of Il1b in a biphasic pattern with reduced Il1b at E12.5 (P = 0.045) and E18.5 (P = 0.067) but increased Il1b at E15.5 (P = 0.031). MCS also induced an upregulation of Vegfa expression in the female placentas at E15.5 (P = 0.034; 4X versus 2X) and E18.5 (P = 0.026; 4X versus 1X). MCS decreased (P = 0.011; 4X versus 1X) placental apoptosis at E10.5. Additionally, the luminal area of the maternal spiral arteries was larger (P ≤ 0.05; 4X versus 1X) in response to extra choline throughout gestation.

DISCUSSION

MCS during murine pregnancy has fetal sex-specific effects on placental inflammation and angiogenesis, with possible consequences on placental vascular development.

Modulators of the Balance between M1 and M2 Macrophages during Pregnancy

Macrophages are a subset of mononuclear phagocytes of the innate immune system with high plasticity and heterogeneity. At the maternal–fetal interface, macrophages are present in all stages of pregnancy and involved in a variety of activities, including regulation of immune cell activities, decidualization, placental cell invasion, angiogenesis, parturition, and postpartum uterine involution. The activation state and function of uterine–placental macrophages are largely dependent on the local tissue microenvironment. However, disruption of the uterine microenvironment can have profound effects on macrophage activity and subsequently impact pregnancy outcome. Thus, appropriately and timely regulated macrophage polarization has been considered a key determinant of successful pregnancy. Targeting macrophage polarization might be an efficient strategy for maintaining maternal–fetal immune homeostasis and a normal pregnancy. Here, we will review the latest findings regarding the modulators regulating macrophage polarization in healthy pregnancies and pregnancy complications, which might provide a basis for macrophage-centered therapeutic strategies.

Sterile inflammation and pregnancy complications: a review

Inflammation is essential for successful embryo implantation, pregnancy maintenance and delivery. In the last decade, important advances have been made in regard to endogenous, and therefore non-infectious, initiators of inflammation, which can act through the same receptors as pathogens. These molecules are referred to as damage-associated molecular patterns (DAMPs), and their involvement in reproduction has only recently been unraveled. Even though inflammation is necessary for successful reproduction, untimely activation of inflammatory processes can have devastating effect on pregnancy outcomes. Many DAMPs, such as uric acid, high-mobility group box 1 (HMGB1), interleukin (IL)-1 and cell-free fetal DNA, have been associated with pregnancy complications, such as miscarriages, preeclampsia and preterm birth in preclinical models and in humans. However, the specific contribution of alarmins to these conditions is still under debate, as currently there is lack of information on their mechanism of action. In this review, we discuss the role of sterile inflammation in reproduction, including early implantation and pregnancy complications. Particularly, we focus on major alarmins vastly implicated in numerous sterile inflammatory processes, such as uric acid, HMGB1, IL-1α and cell-free DNA (especially that of fetal origin) while giving an overview of the potential role of other candidate alarmins.

Modulation of Decidual Macrophage Polarization by Macrophage Colony-Stimulating Factor Derived from First-Trimester Decidual Cells: Implication in Preeclampsia

During human pregnancy, immune tolerance of the fetal semiallograft occurs in the presence of abundant maternal leukocytes. At the implantation site, macrophages comprise approximately 20% of the leukocyte population and act as primary mediators of tissue remodeling. Decidual macrophages display a balance between anti-inflammatory and proinflammatory phenotypes. However, a shift to an M1 subtype is reported in preeclampsia. Granulocyte-macrophage colony-stimulating-factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF) are major differentiating factors that mediate M1 and M2 polarization, respectively. Previously, we observed the following: i) the preeclamptic decidua contains an excess of both macrophages and GM-CSF, ii) the preeclampsia-associated proinflammatory cytokines, IL-1β and tumor necrosis factor-α, markedly enhance GM-CSF and M-CSF expression in cultured leukocyte-free first-trimester decidual cells (FTDCs), iii) FTDC-secreted GM-CSF polarizes macrophages toward an M1 subtype. The microenvironment is a key determinant of macrophage phenotype. Thus, we examined proinflammatory stimulation of FTDC-secreted M-CSF and its role in macrophage development. Immunofluorescence staining demonstrated elevated M-CSF-positive decidual cell numbers in preeclamptic decidua. In FTDCs, IL-1β and tumor necrosis factor-α signal through the NF-κB pathway to induce M-CSF production, which does the following: i) enhances differentiation of and elevates CD163 expression in macrophages, ii) increases macrophage phagocytic capacity, and iii) inhibits signal-regulatory protein α expression by macrophages. These findings suggest that FTDC-secreted M-CSF modulates the decidual immune balance by inducing M2 macrophage polarization and phagocytic capacity in response to proinflammatory stimuli.

The role of decidual cells in uterine hemostasis, menstruation, inflammation, adverse pregnancy outcomes and abnormal uterine bleeding

BACKGROUND

Human pregnancy requires robust hemostasis to prevent hemorrhage during extravillous trophoblast (EVT) invasion of the decidualized endometrium, modification of spiral arteries and post-partum processes. However, decidual hemorrhage (abruption) can occur throughout pregnancy from poorly transformed spiral arteries, causing fetal death or spontaneous preterm birth (PTB), or it can promote the aberrant placentation observed in intrauterine growth restriction (IUGR) and pre-eclampsia; all leading causes of perinatal or maternal morbidity and mortality. In non-fertile cycles, the decidua undergoes controlled menstrual bleeding. Abnormal uterine bleeding (AUB) accompanying progestin-only, long-acting, reversible contraception (pLARC) accounts for most discontinuations of these safe and highly effective agents, thereby contributing to unwanted pregnancies and abortion. The aim of this study was to investigate the role of decidual cells in uterine hemostasis, menstruation, inflammation, adverse pregnancy outcomes and abnormal uterine bleeding.

METHODS

We conducted a critical review of the literature arising from PubMed searches up to December 2015, regarding in situ and in vitro expression and regulation of several specific proteins involved in uterine hemostasis in decidua and cycling endometrium. In addition, we discussed clinical and molecular mechanisms associated with pLARC-induced AUB and pregnancy complications with abruptions, chorioamnionitis or pre-eclampsia.

RESULTS

Progestin-induced decidualization of estradiol-primed human endometrial stromal cells (HESCs) increases in vivo and in vitro expression of tissue factor (TF) and type-1 plasminogen activator inhibitor (PAI-1) while inhibiting plasminogen activators (PAs), matrix metalloproteinases (MMPs), and the vasoconstrictor, endothelin-1 (ET-1). These changes in decidual cell-derived regulators of hemostasis, fibrinolysis, extracellular matrix (ECM) turnover, and vascular tone prevent hemorrhage during EVT invasion and vascular remodeling. In non-fertile cycles, progesterone withdrawal reduces TF and PAI-1 while increasing PA, MMPs and ET-1, causing menstrual-associated bleeding, fibrinolysis, ECM degradation and ischemia. First trimester decidual hemorrhage elicits later adverse outcomes including pregnancy loss, pre-eclampsia, abruption, IUGR and PTB. Decidual hemorrhage generates excess thrombin that binds to decidual cell-expressed protease-activated receptors (PARs) to induce chemokines promoting shallow placentation; such bleeding later in pregnancy generates thrombin to down-regulate decidual cell progesterone receptors and up-regulate cytokines and MMPs linked to PTB. Endometria of pLARC users display ischemia-induced excess vasculogenesis and progestin inhibition of spiral artery vascular smooth muscle cell proliferation and migration leading to dilated fragile vessels prone to bleeding. Moreover, aberrant TF-derived thrombin signaling also contributes to the pathogenesis of endometriosis via induction of angiogenesis, inflammation and cell survival.

CONCLUSION

Perivascular decidualized HESCs promote endometrial hemostasis during placentation yet facilitate menstruation through progestational regulation of hemostatic, proteolytic, and vasoactive proteins. Pathological endometrial hemorrhage elicits excess local thrombin generation, which contributes to pLARC associated AUB, endometriosis and adverse pregnancy outcomes through several biochemical mechanisms.

Macrophage colony-stimulating factor (M-CSF) in first trimester maternal serum: correlation with pathologic pregnancy outcome

PURPOSE

To determine correlations between macrophage colony-stimulating factor (MCSF) levels in maternal blood during first trimester screening with respect to normal and pathological pregnancies.

METHODS

This was a prospective single centre study. First trimester screening was performed according to FMF London certificates. Nuchal translucency, PAPP-A and free β-HCG were obtained as well as M-CSF serum levels in maternal blood. Fetal karyotyping was achieved by chorionic villi sampling.

RESULTS

125 patients were enrolled in this study. 21 pregnancies had confirmed aberrant karyotypes. Trisomy 21 cases showed significantly elevated M-CSF levels of 270 ± 91 pg/ml (p = 0.032), whereas cases of trisomy 13 (183 ± 68 pg/ml) and trisomy 18 (143 ± 40 pg/ml) had low M-CSF levels. Furthermore M-CSF levels tended to be low in preterm deliveries, placental insufficiency and nicotine consumption. In cases with gestational diabetes M-CSF tended to be elevated. Furthermore we found a positive correlation between high free β-human chorionic gonadotropin (hcg) and MCSF values. There was no correlation between pregnancy associated plasma protein (PAPP-A) and M-CSF.

CONCLUSIONS

M-CSF is a cytokine promoting placental growth and differentiation. M-CSF is known to be involved in the process of implantation in pregnancy. The role of M-CSF with respect to disturbed pregnancy outcomes such as placental insufficiency in normal or aberrant karyotypes, for example, is yet subject to further research.

Chinese herbal medicine for miscarriage affects decidual micro-environment and fetal growth

INTRODUCTION

Intrauterine growth restriction complicates 5-10% of pregnancies. This study aims to test the hypothesis that Chinese herbal formula, JLFC01, affects pregnancy and fetal development by modulating the pro-inflammatory decidual micro-environment.

METHODS

Human decidua from gestational age-matched elective terminations or incomplete/missed abortion was immunostained using anti-CD68 + anti-CD86 or anti-CD163 antibodies. qRT-PCR and Luminex assay measured the effects of JLFC01 on IL-1β- or TNF-α-induced cytokine expression in first trimester decidual cells and on an established spontaneous abortion/intrauterine growth restriction (SA/IUGR)-prone mouse placentae. The effect of JLFC01 on human endometrial endothelial cell angiogenesis was evaluated by average area, length and numbers of branching points of tube formation. Food intake, litter size, fetal weight, placental weight and resorption rate were recorded in SA/IUGR-prone mouse treated with JLFC01. qRT-PCR, Western blot and immunohistochemistry assessed the expression of mouse placental IGF-I and IGF-IR.

RESULTS

In spontaneous abortion, numbers of decidual macrophages expressing CD86 and CD163 are increased and decreased, respectively. JLFC01 reduces IL-1β- or TNF-α-induced GM-CSF, M-CSF, C-C motif ligand 2 (CCL2), interferon-γ-inducible protein-10 (IP-10), CCL5 and IL-8 production in first trimester decidual cells. JLFC01 suppresses the activity of IL-1β- or TNF-α-treated first trimester decidual cells in enhancing macrophage-inhibited angiogenesis. In SA/IUGR-prone mice, JLFC01 increases maternal food intake, litter size, fetal and placental weight, and reduces fetal resorption rate. JLFC01 induces IGF-I and IGF-IR expression and inhibits M-CSF, CCL2, CCL5, CCL11, CCL3 and G-CSF expression in the placentae.

DISCUSSION

JLFC01 improves gestation by inhibiting decidual inflammation, enhancing angiogenesis and promoting fetal growth.

M1/M2 macrophage polarity in normal and complicated pregnancy

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

Antiphospholipid antibodies and the placenta: a systematic review of their in vitro effects and modulation by treatment

BACKGROUND

Antiphospholipid antibodies (aPL) are a family of auto-antibodies that are associated with an increased risk of recurrent miscarriage, intrauterine growth restriction and preterm birth. The placenta is a major target of aPL and it is likely that these antibodies promote pregnancy morbidity by affecting trophoblast function. Numerous studies have investigated the effect of aPL on trophoblast function in vitro. However, different trophoblast models and a variety of culture conditions have been employed, resulting in a myriad of different reported findings. This review systematically summarized those published studies that have investigated the effect of aPL on trophoblast function in vitro. In addition, the reported effects of pharmacological treatment on trophoblast function in the presence of aPL were also systematically reviewed.

METHODS

PubMed, Scopus, Embase and Web of Science databases were searched using the keywords 'placenta OR trophoblast' AND 'antiphospholipid antibody OR antiphospholipid syndrome' up to 25 April 2014. Studies were excluded based on the absence of appropriate controls. The effects of aPL on trophoblast proliferation, death, syncytialization, invasion, hormone production, cytokine production, coagulation and complement activation were recorded. The effects of different treatments on the function of trophoblasts in the presence of aPL were also recorded.

RESULTS

A total of 1071 records were retrieved from the four databases. After removing duplicates, the titles and abstracts of 529 articles were reviewed. Of those, 48 articles were read and relevant experimental results were extracted from 47 articles.

CONCLUSIONS

This systematic review provides an overview of all the studies performed to date on the effects of aPL on trophoblast function in vitro. There is considerable support for aPL decreasing trophoblast viability, syncytialization and invasion in vitro. Some work has also suggested that aPL may affect the production of hormones and signalling molecules by trophoblasts, and may stimulate coagulation and complement activation in vitro. Current reports of the in vitro effects of therapeutic treatments on trophoblast function in the presence of aPL are inconclusive. This systematic review has highlighted many gaps in our knowledge of how aPL work and may direct future research in this area.

Interferon-γ protects first-trimester decidual cells against aberrant matrix metalloproteinases 1, 3, and 9 expression in preeclampsia

Human extravillous trophoblast (EVT) invades the decidua via integrin receptors and subsequently degrades extracellular matrix proteins. In preeclampsia (PE), shallow EVT invasion elicits incomplete spiral artery remodeling, causing reduced uteroplacental blood flow. Previous studies show that preeclamptic decidual cells, but not interstitial EVTs, display higher levels of extracellular matrix-degrading matrix metalloproteinase (MMP)-9, but not MMP-2. Herein, we extend our previous PE-related assessment of MMP-2 and MMP-9 to include MMP-1, which preferentially degrades fibrillar collagens, and MMP-3, which can initiate a local proteolytic cascade. In human first-trimester decidual cells incubated with estradiol, tumor necrosis factor-α (TNF-α) significantly enhanced MMP-1, MMP-3, and MMP-9 mRNA and protein levels and activity measured by real-time quantitative RT-PCR, ELISA, immunoblotting, and zymography, respectively. In contrast, interferon γ (IFN-γ) reversed these effects and medroxyprogesterone acetate elicited further reversal. Immunoblotting revealed that p38 mitogen-activated protein kinase signaling mediated TNF-α enhancement of MMP-1, MMP-3, and MMP-9, whereas IFN-γ inhibited p38 mitogen-activated protein kinase phosphorylation. Unlike highly regulated MMP-1, MMP-3, and MMP-9, MMP-2 mRNA and protein expression was constitutive in decidual cells. Because inflammation underlies PE-associated shallow EVT invasion, these results suggest that excess macrophage-derived TNF-α augments expression of MMP-1, MMP-3, and MMP-9 in decidual cells to interfere with normal stepwise EVT invasion of the decidua. In contrast, decidual natural killer cell-derived IFN-γ reverses such TNF-α-induced MMPs to protect against PE.

The activating effect of IFN-γ on monocytes/macrophages is regulated by the LIF-trophoblast-IL-10 axis via Stat1 inhibition and Stat3 activation

Interferon gamma (IFN-γ) and leukemia inhibitory factor (LIF) are key gestational factors that may differentially affect leukocyte function during gestation. Because IFN-γ induces a pro-inflammatory phenotype in macrophages and because trophoblast cells are principal targets of LIF in the placenta, we investigated whether and how soluble factors from trophoblast cells regulate the effects of IFN-γ on macrophage activation. IFN-γ reduces macrophage motility, but enhances Stat1 activation, pro-inflammatory gene expression and cytotoxic functions. Soluble factors from villous cytotrophoblasts (vCT+LIF cells) and BeWo cells (BW/ST+LIF cells) that were differentiated in the presence of LIF inhibit macrophage Stat1 activation but inversely sustain Stat3 activation in response to IFN-γ. vCT+LIF cells produce soluble factors that induce Stat3 activation; this effect is partially abrogated in the presence of neutralizing anti-interleukin 10 (IL-10) antibodies. Moreover, soluble factors from BW/ST+LIF cells reduce cell proliferation but enhance the migratory responses of monocytes. In addition, these factors reverse the inhibitory effect of IFN-γ on monocyte/macrophage motility. BW/ST+LIF cells also generate IFN-γ-activated macrophages with enhanced IL-10 expression, but reduced tumor-necrosis factor alpha (TNF-α), CD14 and CD40 expression as well as impaired cytotoxic function. Additional assays performed in the presence of neutralizing anti-IL-10 antibodies and exogenous IL-10 demonstrate that reduced macrophage cytotoxicity and proliferation, but increased cell motility result from the ability of trophoblast IL-10 to sustain Stat3 activation and suppress IFN-γ-induced Stat1 activation. These in vitro studies are the first to describe the regulatory role of the LIF-trophoblast-IL-10 axis in the process of macrophage activation in response to pro-inflammatory cytokines.

Triiodothyronine regulates angiogenic growth factor and cytokine secretion by isolated human decidual cells in a cell-type specific and gestational age-dependent manner

STUDY QUESTION

Does triiodothyronine (T3) regulate the secretion of angiogenic growth factors and cytokines by human decidual cells isolated from early pregnancy?

SUMMARY ANSWER

T3 modulates the secretion of specific angiogenic growth factors and cytokines, with different regulatory patterns observed amongst various isolated subpopulations of human decidual cells and with a distinct change between the first and second trimesters of pregnancy.

WHAT IS KNOWN ALREADY

Maternal thyroid dysfunction during early pregnancy is associated with complications of malplacentation including miscarriage and pre-eclampsia. T3 regulates the proliferation and apoptosis of fetal-derived trophoblasts, as well as promotes the invasive capability of extravillous trophoblasts (EVT). We hypothesize that T3 may also have a direct impact on human maternal-derived decidual cells, which are known to exert paracrine regulation upon trophoblast behaviour and vascular development at the uteroplacental interface.

STUDY DESIGN, SIZE, DURATION

This laboratory-based study used human decidua from first (8–11 weeks; n = 18) and second (12–16 weeks; n = 12) trimester surgical terminations of apparently uncomplicated pregnancies.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Primary cultures of total decidual cells, and immunomagnetic bead-isolated populations of stromal-enriched (CD10+) and stromal-depleted (CD10−) cells, uterine natural killer cells (uNK cells; CD56+) and macrophages (CD14+) were assessed for thyroid hormone receptors and transporters by immunocytochemistry. Each cell population was treated with T3 (0, 1, 10, 100 nM) and assessments were made of cell viability (MTT assay) and angiogenic growth factor and cytokine secretion (immunomediated assay). The effect of decidual cell-conditioned media on EVT invasion through Matrigel^® was evaluated.

MAIN RESULTS AND THE ROLE OF CHANCE

Immunocytochemistry showed the expression of thyroid hormone transporters (MCT8, MCT10) and receptors (TRα1, TRβ1) required for thyroid hormone-responsiveness in uNK cells and macrophages from the first trimester. The viability of total decidual cells and the different cell isolates were unaffected by T3 so changes in cell numbers could not account for any observed effects. In the first trimester, T3 decreased VEGF-A secretion by total decidual cells (P < 0.05) and increased angiopoietin-2 secretion by stromal-depleted cells (P < 0.05) but in the second trimester total decidual cells showed only increased angiogenin secretion (P < 0.05). In the first trimester, T3 reduced IL-10 secretion by total decidual cells (P < 0.05), and reduced granulocyte macrophage colony stimulating factor (P < 0.01), IL-8 (P < 0.05), IL-10 (P < 0.01), IL-1β (P < 0.05) and monocyte chemotactic protein -1 (P < 0.001) secretion by macrophages, but increased tumour necrosis factor-α secretion by stromal-depleted cells (P < 0.05) and increased IL-6 by uNK cells (P < 0.05). In contrast, in the second trimester T3 increased IL-10 secretion by total decidual cells (P < 0.01) but did not affect cytokine secretion by uNK cells and macrophages. Conditioned media from first trimester T3-treated total decidual cells and macrophages did not alter EVT invasion compared with untreated controls. Thus, treatment of decidual cells with T3 resulted in changes in both angiogenic growth factor and cytokine secretion in a cell type-specific and gestational age-dependent manner, with first trimester decidual macrophages being the most responsive to T3 treatment, but these changes in decidual cell secretome did not affect EVT invasion in vitro.

LIMITATIONS, REASONS FOR CAUTION

Our results are based on in vitro findings and we cannot be certain if a similar response occurs in human pregnancy in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

Optimal maternal thyroid hormone concentrations could play a critical role in maintaining a balanced inflammatory response in early pregnancy to prevent fetal immune rejection and promote normal placental development through the regulation of the secretion of critical cytokines and angiogenic growth factors by human decidual cells. Our data suggest that there is an ontogenically determined regulatory ‘switch’ in T3 responsiveness between the first and second trimesters, and support the notion that the timely and early correction of maternal thyroid dysfunction is critical in influencing pregnancy outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This study is funded by Wellbeing of Women (RG/1082/09 to S.Y.C., M.D.K., J.A.F., L.S.L., G.E.L.) and Action Medical Research – Henry Smith Charity (SP4335 to M.D.K., S.Y.C., L.S.L., J.A.F.). The authors have no conflicts of interest to disclose.

Decidual cell regulation of natural killer cell-recruiting chemokines: implications for the pathogenesis and prediction of preeclampsia

First trimester human decidua is composed of decidual cells, CD56(bright)CD16(-) decidual natural killer (dNK) cells, and macrophages. Decidual cells incubated with NK cell-derived IFN-γ and either macrophage-derived TNF-α or IL-1β synergistically enhanced mRNA and protein expression of IP-10 and I-TAC. Both chemokines recruit CXCR3-expressing NK cells. This synergy required IFN-γ receptor 1 and 2 mediation via JAK/STAT and NFκB signaling pathways. However, synergy was not observed on neutrophil, monocyte, and NK cell-recruiting chemokines. Immunostaining of first trimester decidua localized IP-10, I-TAC, IFN-γR1, and -R2 to vimentin-positive decidual cells versus cytokeratin-positive interstitial trophoblasts. Flow cytometry identified high CXCR3 levels on dNK cells and minority peripheral CD56(bright)CD16(-) pNK cells and intermediate CXCR3 levels on the majority of CD56(dim)CD16(+) pNK cells. Incubation of pNK cells with either IP-10 or I-TAC elicited concentration-dependent enhanced CXCR3 levels and migration of both pNK cell subsets that peaked at 10 ng/mL, whereas each chemokine at a concentration of 50 ng/mL inhibited CXCR3 expression and pNK cell migration. Deciduae from women with preeclampsia, a leading cause of maternal and fetal morbidity and mortality, displayed significantly lower dNK cell numbers and higher IP-10 and I-TAC levels versus gestational age-matched controls. Significantly elevated IP-10 levels in first trimester sera from women eventually developing preeclampsia compared with controls, identifying IP-10 as a novel, robust early predictor of preeclampsia.

Tumor necrosis factor-alpha polymorphism at position -238 in preeclampsia

Background:

Preeclampsia is the most common serious disorder during pregnancy and studies show several immune-related processes in its pathophysiology. The role of cytokines and their expression remains controversial in this field. One of the cytokines of interest in recent studies has been TNF-α, which has been shown to have a higher level in maternal plasma of preeclamptic women.

Objectives:

This study was designed to evaluate the role of TNF-α polymorphism at position -238 in the risk of developing preeclampsia during pregnancy.

Patients and Methods:

One hundred fifty three preeclamptic cases and 140 healthy pregnant women were retrieved from two major hospitals of Mashhad, Iran. Methods a case-control study were designed. Anyone with a history of inflammatory disease, hypertension, or chronic kidney disease was excluded. DNA was extracted from peripheral blood leukocytes. Both groups were genotyped for the polymorphism of the TNF-α gene at position -238 by the RFLP method with Ava II enzyme. Allele and genotype frequencies were compared using one-way ANOVA and the Fisher’s exact test.

Results:

There were significant differences between the two groups in TNF-α genotype at position -238 (P < 0.001). In the preeclamptic group, the frequency of the AA genotype was higher (P < 0.001) and the frequency of the GG genotype was lower (P < 0.001). The overall prevalence of the A allele at position -238 was higher in preeclamptic cases (P < 0.001).

Conclusion:

In this study group, TNF-α -238 polymorphism was shown to be different in preeclamptic and non-preeclamptic pregnant women. The AA genotype and the A allele may carry an increased risk for developing of preeclampsia.

Chemokine CCL28 induces apoptosis of decidual stromal cells via binding CCR3/CCR10 in human spontaneous abortion

Spontaneous abortion is the most common complication of pregnancy. Immune activation and the subsequent inflammation-induced tissue injury are often observed at the maternal-fetal interface as the final pathological assault in recurrent spontaneous abortion. However, the precise mechanisms responsible for spontaneous abortion involving inflammation are not fully understood. Chemokine CCL28 and its receptors CCR3 and CCR10 are important regulators in inflammatory process. Here, we examined the expression of CCL28 and its receptors in decidual stromal cells (DSCs) by immunochemistry and flow cytometry (FCM), and compared their expression level in DSCs from normal pregnancy versus spontaneous abortion, and their relationship to inflammatory cytokines production by DSCs. We further analyzed regulation of the pro-inflammatory cytokines on CCL28 expression in DSCs by real-time polymerase chain reaction, In-cell Western and FCM. The effects of CCL28-CCR3/CCR10 interaction on DSC apoptosis was investigated by Annexin V staining and FCM analysis or DAPI staining and nuclear morphology. Higher levels of the inflammatory cytokines interleukin (IL)-1β, IL-17A and tumor necrosis factor-α, and increased CCR3/CCR10 expression were observed in DSCs from spontaneous abortion compared with normal pregnancy. Treatment with inflammatory cytokines differently affected CCL28 and CCR3/CCR10 expression in DSCs. Human recombinant CCL28 promoted DSC apoptosis, which was eliminated by pretreatment with neutralizing antibodies against CCR3/CCR10 and CCL28. However, CCL28 did not affect DSC growth. These results suggest that the inflammation-promoted up-regulation of CCL28 and its receptors interaction in DSCs is involved in human spontaneous abortion via inducing DSC apoptosis.

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.

Interstitial trophoblast cells: an enigmatic and variable component of the developing macaque placenta

The distribution of cytokeratin-positive interstitial trophoblast cells in the endometrium of the macaque during placental development was examined. Such cells are moderately abundant only from the 15th through the 22th day of pregnancy, although there is considerable individual variation. During this period of gestation, interstitial trophoblast cells are distributed in the perivascular stroma immediately surrounding spiral arteries, including coils of arteries already invaded by endovascular trophoblast. The interstitial trophoblast cells are not seen to directly intrude into the smooth muscle of the spiral arteries. Very few interstitial trophoblast cells are present from days 12 through 14 of gestation when the arteries are first invaded by endovascular trophoblast. Even fewer interstitial trophoblast cells are seen after day 30 of gestation. The brief time in gestation when interstitial trophoblast cells are abundant coincides with a time when spiral arteries are undergoing rapid modification into patent uteroplacental arteries. It is suggested that during this period, the interstitial trophoblast cells may facilitate changes in shape of the spiral arteries by alterations of the perivascular connective tissue, perhaps through interactions with other cellular constituents rather than by directly modifying the arteries per se.

Key cellular components and interactive histocompatibility molecules regulating tolerance to the fetal allograft

Implantation is a major landmark in life. It involves the correct apposition of the embryo in the maternal endometrium. The cellular environment influences placenta development, and direct contact of the fetus with maternal tissues is achieved through decidual cells. At the decidua, and at systemic level, the correct balance of cells potentially acting as antigen-presenting cells and histocompatibility products play a pivotal role in achieving feto-maternal tolerance. Here, we review some of the current issues associated with the interplay between cells and molecules needed for pregnancy development.