Leptin-Mediated Induction of IL-6 Expression in Hofbauer Cells Contributes to Preeclampsia Pathogenesis

Leptin plays a crucial role in regulating energy homoeostasis, neuroendocrine function, metabolism, and immune and inflammatory responses. The adipose tissue is a main source of leptin, but during pregnancy, leptin is also secreted primarily by the placenta. Circulating leptin levels peak during the second trimester of human pregnancy and fall after labor. Several studies indicated a strong association between elevated placental leptin levels and preeclampsia (PE) pathogenesis and elevated serum interleukin-6 (IL-6) levels in PE patients. Therefore, we hypothesized that a local increase in placental leptin production induces IL-6 production in Hofbauer cells (HBCs) to contribute to PE-associated inflammation. We first investigated HBCs-specific IL-6 and leptin receptor (LEPR) expression and compared their immunoreactivity in PE vs. gestational age-matched control placentas. Subsequently, we examined the in vitro regulation of IL-6 as well as the phosphorylation levels of intracellular signaling proteins STAT3, STAT5, NF-κB, and ERK1/2 by increasing recombinant human leptin concentrations (10 to 1000 ng/mL) in primary cultured HBCs. Lastly, HBC cultures were incubated with leptin ± specific inhibitors of STAT3 or STAT5, or p65 NF-κB or ERK1/2 MAPK signaling cascades to determine relevant cascade(s) involved in leptin-mediated IL-6 regulation. Immunohistochemistry revealed ~three- and ~five-fold increases in IL-6 and LEPR expression, respectively, in HBCs from PE placentas. In vitro analysis indicated that leptin treatment in HBCs stimulate IL-6 in a concentration-dependent manner both at the transcriptional and secretory levels (p < 0.05). Moreover, leptin-treated HBC cultures displayed significantly increased phosphorylation levels of STAT5, p65 NF-κB, and ERK1/2 MAPK and pre-incubation of HBCs with a specific ERK1/2 MAPK inhibitor blocked leptin-induced IL-6 expression. Our in situ results show that HBCs contribute to the pathogenesis of PE by elevating IL-6 expression, and in vitro results indicate that induction of IL-6 expression in HBCs is primarily leptin-mediated. While HBCs display an anti-inflammatory phenotype in normal placentas, elevated levels of leptin may transform HBCs into a pro-inflammatory phenotype by activating ERK1/2 MAPK to augment IL-6 expression.

Maternal respiratory SARS-CoV-2 infection in pregnancy is associated with a robust inflammatory response at the maternal-fetal interface

BACKGROUND

Pregnant women are at increased risk for severe outcomes from coronavirus disease 2019 (COVID-19), but the pathophysiology underlying this increased morbidity and its potential effect on the developing fetus is not well understood.

METHODS

We assessed placental histology, ACE2 expression, and viral and immune dynamics at the term placenta in pregnant women with and without respiratory severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

FINDINGS

The majority (13 of 15) of placentas analyzed had no detectable viral RNA. ACE2 was detected by immunohistochemistry in syncytiotrophoblast cells of the normal placenta during early pregnancy but was rarely seen in healthy placentas at full term, suggesting that low ACE2 expression may protect the term placenta from viral infection. Using immortalized cell lines and primary isolated placental cells, we found that cytotrophoblasts, the trophoblast stem cells and precursors to syncytiotrophoblasts, rather than syncytiotrophoblasts or Hofbauer cells, are most vulnerable to SARS-CoV-2 infection in vitro. To better understand potential immune mechanisms shielding placental cells from infection in vivo, we performed bulk and single-cell transcriptomics analyses and found that the maternal-fetal interface of SARS-CoV-2-infected women exhibited robust immune responses, including increased activation of natural killer (NK) and T cells, increased expression of interferon-related genes, as well as markers associated with pregnancy complications such as preeclampsia.

CONCLUSIONS

SARS-CoV-2 infection in late pregnancy is associated with immune activation at the maternal-fetal interface even in the absence of detectable local viral invasion.

FUNDING

NIH (T32GM007205, F30HD093350, K23MH118999, R01AI157488, U01DA040588) and Fast Grant funding support from Emergent Ventures at the Mercatus Center.

SARS-CoV-2 infection in pregnancy is associated with robust inflammatory response at the maternal-fetal interface

Pregnant women appear to be at increased risk for severe outcomes associated with COVID-19, but the pathophysiology underlying this increased morbidity and its potential impact on the developing fetus is not well understood. In this study of pregnant women with and without COVID-19, we assessed viral and immune dynamics at the placenta during maternal SARS-CoV-2 infection. Amongst uninfected women, ACE2 was detected by immunohistochemistry in syncytiotrophoblast cells of the normal placenta during early pregnancy but was rarely seen in healthy placentas at full term. Term placentas from women infected with SARS-CoV-2, however, displayed a significant increase in ACE2 levels. Using immortalized cell lines and primary isolated placental cells, we determined the vulnerability of various placental cell types to direct infection by SARS-CoV-2 in vitro. Yet, despite the susceptibility of placental cells to SARS-CoV-2 infection, viral RNA was detected in the placentas of only a subset (~13%) of women in this cohort. Through single cell transcriptomic analyses, we found that the maternal-fetal interface of SARS-CoV-2-infected women exhibited markers associated with pregnancy complications, such as preeclampsia, and robust immune responses, including increased activation of placental NK and T cells and increased expression of interferon-related genes. Overall, this study suggests that SARS-CoV-2 is associated with immune activation at the maternal-fetal interface even in the absence of detectable local viral invasion. While this likely represents a protective mechanism shielding the placenta from infection, inflammatory changes in the placenta may also contribute to poor pregnancy outcomes and thus warrant further investigation.

Acetaminophen Attenuates invasion and alters the expression of extracellular matrix enzymes and vascular factors in human first trimester trophoblast cells

Acetaminophen is one of the most common medications taken during pregnancy, considered safe for maternal health and fetal development. However, recent epidemiological studies have associated prenatal acetaminophen use with several developmental disorders in offspring. As acetaminophen can freely cross into and through the placenta, epidemiological associations with prenatal acetaminophen use may reflect direct actions on the fetus and/or the impact of altered placental functions. In the absence of rigorous mechanistic studies, our understanding of how prenatal acetaminophen exposure can cause long-term effects in offspring is limited. The objective of this study was to determine whether acetaminophen can alter key functions of a major placental cell type by utilizing immortalized human first trimester trophoblast cells. This study employed a comparative analysis with the nonsteroidal, anti-inflammatory drug aspirin, which has established effects in first trimester trophoblast cells. We report that immortalized trophoblast cells express the target proteins of acetaminophen and aspirin: cyclooxygenase (COX) -1 and -2. Unlike aspirin, acetaminophen significantly repressed the expression of angiogenesis and vascular remodeling genes in HTR-8/SVneo cells. Moreover, acetaminophen impaired trophoblast invasion by over 80%, while aspirin had no effect on invasion. Acetaminophen exposure reduced the expression of matrix metalloproteinase (MMP)-2 and -9 and increased the expression of tissue inhibitors of matrix metalloproteinases 2, leading to an imbalance in the ratio of proteolytic enzymes. Finally, a bioinformatic approach identified novel acetaminophen-responsive gene networks associated with key trophoblast functions and disease. Together these results suggest that prenatal acetaminophen use may interfere with critical trophoblast functions early in gestation, which may subsequently impact fetal development.

Zika Virus-Infected Decidual Cells Elicit a Gestational Age-Dependent Innate Immune Response and Exaggerate Trophoblast Zika Permissiveness: Implication for Vertical Transmission

Vertical transmission of the Zika virus (ZIKV) causes severe fetal defects, but the exact pathogenic mechanism is unclear. We identified up to a 10,480-fold higher expression of viral attachment factors AXL, GAS6, and PROS1 and a 3880-fold increase in ZIKV infectiousness/propagation in human term decidual stromal cells versus trophoblasts. Moreover, levels of viral attachment factors and ZIKV are significantly increased, whereas expression of innate immune response genes are significantly decreased, in human first trimester versus term decidual cells. ZIKV-infected decidual cell supernatants increased cytotrophoblasts infection up to 252-fold compared with directly infected cytotrophoblasts. Tizoxanide treatment efficiently inhibited Zika infection in both maternal and fetal cells. We conclude that ZIKV permissiveness, as well as innate immune responsiveness of human decidual cells, are gestational age dependent, and decidual cells augment ZIKV infection of primary human cytotrophoblast cultures, which are otherwise ZIKV resistant. Human decidual cells may act as reservoirs for trimester-dependent placental transmission of ZIKV, accounting for the higher Zika infection susceptibility and more severe fetal sequelae observed in early versus late pregnancy. Moreover, tizoxanide is a promising agent in preventing perinatal Zika transmission as well as other RNA viruses such as coronavirus.

Peri-implantation cytokine profile differs between singleton and twin IVF pregnancies

PROBLEM

It is unknown whether maternal cytokine production differs between twin and singleton gestations in the implantation phase. A difference in maternal serum cytokine concentrations in twins would imply a dose-response to the invading embryos, as opposed to a general immune reaction.

METHOD OF STUDY

A prospective longitudinal cohort of women aged 18-45 at an academic fertility center undergoing in vitro fertilization and embryo transfer (IVF-ET) underwent routine collection of serial serum samples starting 9 days after ET and then approximately every 48 hours thereafter. Cryopreserved aliquots of these samples were assayed for interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α), and C-X-C motif chemokine ligand 10 (CXCL10) using the SimplePlex immunoassay platform. Pregnancies were followed until delivery. Serial measures of serum concentrations of IL-10, CXCL10, and TNF-α in singleton or di-di twin pregnancies from 9 to 15 days after IVF-ET were compared.

RESULTS

Maternal serum levels of CXCL10 are significantly lower in women with di-di twin pregnancies in early implantation compared to those with singleton gestation (day 9-11, P = .02). Serum levels of TNF-α and IL-10 were comparable at all studied time points (P > .05).

CONCLUSION

Maternal serum levels of CXCL10 are significantly lower in the earliest implantation phase in di-di twins compared to singleton conceptions. Given the known anti-angiogenic role of CXCL10, we hypothesize that lower CXCL10 levels in twin implantations allow an environment that is conducive for the greater vascularization required for the establishment of dual placentation in di-di twins.

Trophoblast-secreted soluble-PD-L1 modulates macrophage polarization and function

Decidual macrophages are in close contact with trophoblast cells during placenta development, and an appropriate crosstalk between these cellular compartments is crucial for the establishment and maintenance of a healthy pregnancy. During different phases of gestation, macrophages undergo dynamic changes to adjust to the different stages of fetal development. Trophoblast-secreted factors are considered the main modulators responsible for macrophage differentiation and function. However, the phenotype of these macrophages induced by trophoblast-secreted factors and the factors responsible for their polarization has not been elucidated. In this study, we characterized the phenotype and function of human trophoblast-induced macrophages. Using in vitro models, we found that human trophoblast-educated macrophages were CD14⁺ CD206⁺ CD86^- and presented an unusual transcriptional profile in response to TLR4/LPS activation characterized by the expression of type I IFN-β expression. IFN-β further enhances the constitutive production of soluble programmed cell death ligand 1 (PD-L1) from trophoblast cells. PD-1 blockage inhibited trophoblast-induced macrophage differentiation. Soluble PD-L1 (sPD-L1) was detected in the blood of pregnant women and increased throughout the gestation. Collectively, our data suggest the existence of a regulatory circuit at the maternal fetal interface wherein IFN-β promotes sPD-L1 expression/secretion by trophoblast cells, which can then initiate a PD-L1/PD-1-mediated macrophage polarization toward an M2 phenotype, consequently decreasing inflammation. Macrophages then maintain the expression of sPD-L1 by the trophoblasts through IFN-β production induced through TLR4 ligation.

Human Chorionic Gonadotropin modulates CXCL10 Expression through Histone Methylation in human decidua

The process of implantation, trophoblast invasion and placentation demand continuous adaptation and modifications between the trophoblast (embryonic) and the decidua (maternal). Within the decidua, the maternal immune system undergoes continued changes, as the pregnancy progress, in terms of the cell population, phenotype and production of immune factors, cytokines and chemokines. Human chorionic gonadotropin (hCG) is one of the earliest hormones produced by the blastocyst and has potent immune modulatory effects, especially in relation to T cells. We hypothesized that trophoblast-derived hCG modulates the immune population present at the maternal fetal interface by modifying the cytokine profile produced by the stromal/decidual cells. Using in vitro models from decidual samples we demonstrate that hCG inhibits CXCL10 expression by inducing H3K27me3 histone methylation, which binds to Region 4 of the CXCL10 promoter, thereby suppressing its expression. hCG-induced histone methylation is mediated through EZH2, a functional member of the PRC2 complex. Regulation of CXCL10 expression has a major impact on the capacity of endometrial stromal cells to recruit CD8 cells. We demonstrate the existence of a cross talk between the placenta (hCG) and the decidua (CXCL10) in the control of immune cell recruitment. Alterations in this immune regulatory function, such as during infection, will have detrimental effects on the success of the pregnancy.

Herpesvirus-infected Hofbauer cells activate endothelial cells through an IL-1β-dependent mechanism

INTRODUCTION

Placental viral infections are associated with fetal inflammation and adverse pregnancy outcomes. However, there have been limited studies on how placental macrophages in the villous and adjacent fetal umbilical endothelial cells respond to a viral insult. This study aimed to evaluate the communication between Hofbauer cells (HBCs) and human umbilical vein endothelial cells (HUVECs) during a viral infection.

METHODS

HBCs were either uninfected or infected with the γ-herpesvirus, MHV-68, and the conditioned medium (CM) collected. HUVECs were exposed to HBC CM and the levels of the pro-neutrophilic response markers: IL-8; E-selectin; intercellular adhesion molecule 1 (ICAM-1); and vascular adhesion molecule 1 (VCAM-1) measured by ELISA and qPCR. The role of HBC-derived IL-1β was investigated using an IL-1β blocking antibody (Ab) or IL-1 receptor antagonist (IL-1Ra).

RESULTS

MHV-68 infection of HBCs induced a significant increase in IL-1β secretion. CM from infected HBCs induced HUVEC expression of IL-8, E-selectin, VCAM-1, ICAM-1 mRNA, and secretion of IL-8. The HUVEC response to the CM of MHV-infected HBCs was inhibited by a neutralizing IL-1β Ab and by IL-1Ra.

DISCUSSION

Virally-induced HBC IL-1β activates HUVECs to generate a pro-neutrophilic response. This novel cell-cell communication pathway may play an important role in the genesis of fetal inflammation associated with placental viral infection.

IL-10 to TNFα ratios throughout early first trimester can discriminate healthy pregnancies from pregnancy losses

PROBLEM

Embryo implantation and placentation require a careful immunological balance. Cytokines such as IL-10 and TNFα have been implicated as markers of dysregulation, but have only been studied at a single time point or after a pregnancy loss. Our objective was to determine normative patterns of serum levels of IL-10 and TNFα and their ratio throughout the first trimester in healthy pregnancies and to determine if this pattern differs from pregnancy loss.

METHOD OF STUDY

Two prospective longitudinal cohorts of gravidae including in vitro fertilization (IVF) and naturally conceived pregnancies with serial blood draws. Cytokines were assayed using Simple Plex. In the IVF cohort, we monitored from the implantation day up to 6 weeks of gestation; whereas in the naturally conceived cohort, sample collection began at 4 weeks and throughout the whole first trimester.

RESULTS

IL-10 concentrations in normal pregnancies were significantly higher than in pregnancies ending in a loss starting at 6-8 weeks of gestation, while TNFα concentrations were significantly lower in normal than in pregnancies ending in a loss starting at 3-5 of gestation weeks. The IL-10 to TNFα ratio in normal pregnancies was significantly higher from 4 to 9 weeks compared to pregnancies that were lost (t test, P < .05). Changes were observed before any symptoms of miscarriage were present.

CONCLUSION

We provide evidences of differences in early immunomodulation in healthy pregnancies vs those destined to end in first-trimester loss. The ratio of IL-10 to TNFα rises significantly higher in viable pregnancies as early as 4.5 weeks compared to pregnancies loss.

Thermal stability of cytokines: A review

BACKGROUND

The role of cytokines in various disease states is a burgeoning field of academic study and clinical application, however there are no consensus documents on how certain cytokines should be stored prior to quantification. This information is especially of interest to researchers assembling a biobank or clinicians who have to transport specimens to a different location in order to be tested.

OBJECTIVE

To review the literature and synthesize prior findings on cytokine storage and freeze/thaw stability.

DESIGN

We searched PubMed for articles related to cytokine storage stability. All articles were analyzed for cytokines studied, source of reported cytokine concentration (i.e., human whole blood or serum, concentrations from other species or bodily sources were excluded), and reported statistical results.

RESULTS

We identified and synthesized results of 23 peer-reviewed articles which published data on the storage and freeze/thaw stability of 33 different cytokines and chemokines.

CONCLUSION

There is a wide variety of reported cytokine storage and freeze/thaw stability. Interleukin-6 and tumor necrosis factor alpha are the most widely studied cytokines in regard to temperature stability. In a few cytokines, a clear consensus can be reached as to storage safety at particular temperatures, but in most, more research needs to be done and we advise the clinician or researcher to use caution in interpreting cytokine concentration results after a long period of storage or several freeze/thaw cycles.

Differential gene expression during placentation in pregnancies conceived with different fertility treatments compared with spontaneous pregnancies

OBJECTIVE

To identify differences in the transcriptomic profiles during placentation from pregnancies conceived spontaneously vs. those with infertility using non-in vitro fertilization (IVF) fertility treatment (NIFT) or IVF.

DESIGN

Cohort study.

SETTING

Academic medical center.

PATIENT(S)

Women undergoing chorionic villus sampling at gestational age 11-13 weeks (n = 141), with pregnancies that were conceived spontaneously (n = 74), with NIFT (n = 33), or with IVF (n = 34), resulting in the delivery of viable offspring.

INTERVENTION(S)

Collection of chorionic villus samples from women who conceived spontaneously, with NIFT, or with IVF for gene expression analysis using RNA sequencing.

MAIN OUTCOME MEASURE(S)

Baseline maternal, paternal, and fetal demographics, maternal medical conditions, pregnancy complications, and outcomes. Differential gene expression of first-trimester placenta.

RESULT(S)

There were few differences in the transcriptome of first-trimester placenta from NIFT, IVF, and spontaneous pregnancies. There was one protein-coding differentially expressed gene (DEG) between the spontaneous and infertility groups, CACNA1I, one protein-coding DEG between the spontaneous and IVF groups, CACNA1I, and five protein-coding DEGs between the NIFT and IVF groups, SLC18A2, CCL21, FXYD2, PAEP, and DNER.

CONCLUSION(S)

This is the first and largest study looking at transcriptomic profiles of first-trimester placenta demonstrating similar transcriptomic profiles in pregnancies conceived using NIFT or IVF and spontaneous conceptions. Gene expression differences found to be highest in the NIFT group suggest that the underlying infertility, in addition to treatment-related factors, may contribute to the observed gene expression profiles.

H19 long noncoding RNA alters trophoblast cell migration and invasion by regulating TβR3 in placentae with fetal growth restriction

Fetal growth restriction (FGR) is a well-recognized risk factor for perinatal mortality and morbidity, as well as neurodevelopmental impairment and adulthood onset disorders. Here we report that the H19 long noncoding RNA (lncRNA) is significantly decreased in placentae from pregnancies with FGR. Downregulation of H19 leads to reduced migration and invasion of extravillous trophoblast (EVT) cells in vitro. This is consistent with reduced trophoblast invasion that has been observed in FGR. Genome-scale transcriptome profiling of EVT cells reveals significantly decreased expression of the type III TGF-β receptor (TβR3) following H19 knockdown. Decreased TβR3 expression is also seen in FGR placentae. TβR3 repression decreases EVT cell migration and invasion, owing to impaired TGF-β signaling through a non-canonical TGF-β signaling pathway. Further, we identify TβR3 as a novel regulatory target of microRNA let-7. We propose that dysregulation of this newly identified H19/TβR3-mediated regulatory pathway may contribute to the molecular mechanism of FGR. Our findings are the first to show a lncRNA-based mechanism of FGR, holding promise for the development of novel predictive, diagnostic, and therapeutic modalities for FGR.

Low molecular weight heparin and aspirin exacerbate human endometrial endothelial cell responses to antiphospholipid antibodies

PROBLEM

Women with antiphospholipid antibodies (aPL) are at risk for pregnancy complications despite treatment with low molecular weight heparin (LMWH) or aspirin (ASA). aPL recognizing beta2 glycoprotein I can target the uterine endothelium, however, little is known about its response to aPL. This study characterized the effect of aPL on human endometrial endothelial cells (HEECs), and the influence of LMWH and ASA.

METHOD OF STUDY

HEECs were exposed to aPL or control IgG, with or without low-dose LMWH and ASA, alone or in combination. Chemokine and angiogenic factor secretion were measured by ELISA. A tube formation assay was used to measure angiogenesis.

RESULTS

aPL increased HEEC secretion of pro-angiogenic VEGF and PlGF; increased anti-angiogenic sFlt-1; inhibited basal secretion of the chemokines MCP-1, G-CSF, and GRO-α; and impaired angiogenesis. LMWH and ASA, alone and in combination, exacerbated the aPL-induced changes in the HEEC angiogenic factor and chemokine profile. There was no reversal of the aPL inhibition of HEEC angiogenesis by either single or combination therapy.

CONCLUSION

By aPL inhibiting HEEC chemokine secretion and promoting sFlt-1 release, the uterine endothelium may contribute to impaired placentation and vascular transformation. LMWH and ASA may further contribute to endothelium dysfunction in women with obstetric APS.

Viral Infection Sensitizes Human Fetal Membranes to Bacterial Lipopolysaccharide by MERTK Inhibition and Inflammasome Activation

Chorioamnionitis, premature rupture of fetal membranes (FMs), and subsequent preterm birth are associated with local infection and inflammation, particularly IL-1β production. Although bacterial infections are commonly identified, other microorganisms may play a role in the pathogenesis. Because viral pandemics, such as influenza, Ebola, and Zika, are becoming more common, and pregnant women are at increased risk for associated complications, this study evaluated the impact that viral infection had on human FM innate immune responses. This study shows that a herpes viral infection of FMs sensitizes the tissue to low levels of bacterial LPS, giving rise to an exaggerated IL-1β response. Using an ex vivo human FM explant system and an in vivo mouse model of pregnancy, we report that the mechanism by which this aggravated inflammation arises is through the inhibition of the TAM receptor, MERTK, and activation of the inflammasome. The TAM receptor ligand, growth arrest specific 6, re-establishes the normal FM response to LPS by restoring and augmenting TAM receptor and ligand expression, as well as by preventing the exacerbated IL-1β processing and secretion. These findings indicate a novel mechanism by which viruses alter normal FM immune responses to bacteria, potentially giving rise to adverse pregnancy outcomes.

Nucleated Red Blood Cells as a Marker of Acute and Chronic Fetal Hypoxia in a Rat Model

OBJECTIVE

To examine the relationship between duration of fetal hypoxia, nucleated red blood cell (NRBC) count, and fetal growth.

METHODS

Pregnant rats were exposed to a severe hypoxia (9.5%-10% O₂) for varying time intervals (2, 6, 12, 24, 48, and 120 hours; n=4 for each time interval) immediately prior to delivery at term. Normoxic controls were exposed to room air (21% O₂) and matched for all other study variables (n=4 rats for each time interval). Pups were delivered via hysterotomy while maintaining exposure gas concentrations. Blood gas analysis and NRBC counts were performed, and fetal body and liver weights were recorded. Student's t test and simple regression were used for statistical analysis.

RESULTS

As the duration of hypoxia increased, fetal weight, liver weight, blood bicarbonate, and base excess levels decreased significantly; concomitantly, NRBC counts increased. This increase in NRBCs became statistically significant after 24 hours of exposure. After 48 hours of hypoxia there was a 2.5-fold rise in NRBC count, and after 120 hours of hypoxia there was a 4.5-fold rise in NRBC count over control levels. After 12 or more hours of hypoxia, fetal body weights were significantly reduced; 120 hours of hypoxia resulted in a 35% reduction in fetal body weight, a 34% reduction in fetal liver weight, and 356% increase in NRBC count.

CONCLUSION

In a pregnant rat model, chronic maternal hypoxia (≥24 hours) results in a significant increase in fetal NRBC counts as well as reduced fetal body weight and organ growth.

Zika virus infection of Hofbauer cells

Recent studies have linked antenatal infection with Zika virus (ZIKV) with major adverse fetal and neonatal outcomes, including microcephaly. There is a growing consensus for the existence of a congenital Zika syndrome (CZS). Previous studies have indicated that non-placental macrophages play a key role in the replication of dengue virus (DENV), a closely related flavivirus. As the placenta provides the conduit for vertical transmission of certain viruses, and placental Hofbauer cells (HBCs) are fetal-placental macrophages located adjacent to fetal capillaries, it is not surprising that several recent studies have examined infection of HBCs by ZIKV. In this review, we describe congenital abnormalities associated with ZIKV infection, the role of HBCs in the placental response to infection, and evidence for the susceptibility of HBCs to ZIKV infection. We conclude that HBCs may contribute to the spread of ZIKV in placenta and promote vertical transmission of ZIKV, ultimately compromising fetal and neonatal development and function. Current evidence strongly suggests that further studies are warranted to dissect the specific molecular mechanism through which ZIKV infects HBCs and its potential impact on the development of CZS.

Optimization of techniques for multiple platform testing in small, precious samples such as human chorionic villus sampling

BACKGROUND

Multiple testing to understand global changes in gene expression based on genetic and epigenetic modifications is evolving. Chorionic villi, obtained for prenatal testing, is limited, but can be used to understand ongoing human pregnancies. However, optimal storage, processing and utilization of CVS for multiple platform testing have not been established.

RESULTS

Leftover CVS samples were flash-frozen or preserved in RNAlater. Modifications to standard isolation kits were performed to isolate quality DNA and RNA from samples as small as 2-5 mg. RNAlater samples had significantly higher RNA yields and quality and were successfully used in microarray and RNA-sequencing (RNA-seq). RNA-seq libraries generated using 200 versus 800-ng RNA showed similar biological coefficients of variation. RNAlater samples had lower DNA yields and quality, which improved by heating the elution buffer to 70 °C. Purification of DNA was not necessary for bisulfite-conversion and genome-wide methylation profiling. CVS cells were propagated and continue to express genes found in freshly isolated chorionic villi.

CONCLUSIONS

CVS samples preserved in RNAlater are superior. Our optimized techniques provide specimens for genetic, epigenetic and gene expression studies from a single small sample which can be used to develop diagnostics and treatments using a systems biology approach in the prenatal period. © 2016 John Wiley & Sons, Ltd.

Dynamics of Base Excision Repair at the Maternal-Fetal Interface in Pregnancies Complicated by Preeclampsia

Preeclampsia (PE) (gestational proteinuric hypertension) is the leading cause of maternal and perinatal mortality worldwide. Although placental endothelial dysfunction and oxidative stress are known to contribute to PE, the exact pathological basis for this disorder remains unclear. Previously, we demonstrated that DNA damage at the maternal-fetal interface is more common in the placentas of women with PE than normotensive controls. In this study, we utilized an in vivo comparative study, including 20 preeclamptic women and 8 healthy control subjects, and an in vitro hypoxia/reperfusion model to mimic the effects of oxidative stress at the maternal-fetal interface. We tracked the spatial pattern of expression of 2 base excision repair proteins, 8-oxoguanine glycosylase (OGG1) and apurinic/apyrimidinic endonuclease-1 (APE1), at the maternal-fetal interface in response to oxidative stress. In vivo, we found a significant increase in OGG1 and APE1 concentrations in PE placental tissues as compared to normotensive controls ( P < .0001). Further, our in vitro study revealed that OGG1 and APE1 expression is much greater in maternal cells (decidua) than in fetal cells (cytotrophoblasts) of placental tissue subjected to oxidative stress ( P < .0001). Our results suggest that OGG1 and APE1 likely protect decidual cells from oxidative base damage.

Zika virus productively infects primary human placenta-specific macrophages

The strong association of Zika virus infection with congenital defects has led to questions of how a flavivirus is capable of crossing the placental barrier to reach the fetal brain. Here, we demonstrate permissive Zika virus infection of primary human placental macrophages, commonly referred to as Hofbauer cells, and placental villous fibroblasts. We also demonstrate Zika virus infection of Hofbauer cells within the context of the tissue ex vivo using term placental villous explants. In addition to amplifying infectious virus within a usually inaccessible area, the putative migratory activities of Hofbauer cells may aid in dissemination of Zika virus to the fetal brain. Understanding the susceptibility of placenta-specific cell types will aid future work around and understanding of Zika virus-associated pregnancy complications.

First trimester trophoblast cells secrete Fas ligand which induces immune cell apoptosis

Since the invading trophoblast represents a semi-allograft, it should be rejected by the mother. It has, therefore, been postulated that during normal pregnancy the trophoblast evades the maternal immune system though the establishment of immune privilege by triggering the death of activated lymphocytes which may be sensitized to paternal alloantigens. Such peripheral tolerance may be directed through the Fas/Fas ligand (FasL) apoptotic pathway and mediated by FasL expressed by the trophoblast. However, in vivo studies show that membrane-associated expression of FasL may instead promote allograft rejection, rather than protection. The aim of this study was to determine if there is a role for FasL in trophoblast immune privilege. In this study, we demonstrate that isolated first trimester trophoblast cells lack membrane-associated FasL, but express a cytoplasmic form in association with a specialized secretory lysosomal pathway. Furthermore, this intracellular FasL is constitutively secreted by trophoblast cells via the release of microvesicles. Following disruption of these microvesicles, the whole 37 kDa secreted FasL is able to induce T-cell death by apoptosis through activation of the Fas pathway. Therefore, we propose that secretion of FasL may be one mechanism by which trophoblast cells promote a state of immune privilege and, therefore, protect themselves from maternal immune recognition.

Toll-like receptor-mediated responses by placental Hofbauer cells (HBCs): a potential pro-inflammatory role for fetal M2 macrophages

PROBLEM

Microbial-driven responses in placenta are linked with adverse pregnancy outcomes. The role of Toll-like receptor (TLR) function in Hofbauer cells (HBCs) and fetal macrophages of the placental villous core remains understudied.

METHOD OF STUDY

Flow cytometry and immunohistochemistry (IHC) were used to establish the phenotype of HBCs. Regulation of cytokine secretion in response to treatment with TLR agonists and expression levels of TLRs and co-activators were compared in HBCs, placental fibroblasts (FIBs), and human umbilical vein endothelial cells (HUVECs) using ELISA and qPCR.

RESULTS

Although flow cytometry and IHC revealed HBCs to be M2 (anti-inflammatory) macrophages, LPS and polyinosinic: polycytidylic acid [poly (I:C)] treatments markedly enhanced IL-6 secretion by HBCs, and expression of TLR-2, TLR-3, TLR-4, CD14, and MD-2 was the highest in HBCs.

CONCLUSION

These results indicate that although HBCs are M2 macrophages, inflammatory responses are induced through TLR-3 and TLR-4 in this cell type, suggesting a role in microbial-driven placental/fetal inflammation.

Trophoblast induces monocyte differentiation into CD14+/CD16+ macrophages

PROBLEM

During early pregnancy, macrophages and trophoblast come into close contact during placenta development, and regulated cross talk between these cellular compartments is crucial for maintaining a healthy pregnancy. As trophoblast cells constitutively secrete many chemokines and cytokines, we hypothesize that trophoblast-secreted factors can differentiate monocytes into a decidual phenotype. In this study, we describe a unique macrophage phenotype, following monocytes' exposure to trophoblast-soluble factors.

METHOD OF STUDY

Peripheral blood monocytes were treated with or without conditioned media (CM) from first trimester trophoblast cells. Phenotypic changes and phagocytic capacity were determined by flow cytometry. Cytokine and chemokine production was determined by multiplex analysis.

RESULTS

Monocytes exposed to trophoblast factors undergo morphologic changes characterized by a gain in size and complexity and acquire a unique phenotype characterized by gain of CD14 surface expression as well as CD16. The presence of CD14+/CD16+ macrophages was confirmed in normal decidua. These cells secrete higher levels of IL-1b, IL-10, and IP-10 and have increased capacity for phagocytosis.

CONCLUSION

We demonstrate that trophoblast-secreted factors can induce monocyte differentiation into a unique macrophage phenotype. These findings suggest that the microenvironment of the placenta can modulate the phenotype of macrophages present at the decidua.

Single- and double-stranded viral RNA generate distinct cytokine and antiviral responses in human fetal membranes

There has been growing interest in the role of viral infections and their association with adverse pregnancy outcomes. However, little is known about the impact viral infections have on the fetal membranes (FM). Toll-like receptors (TLR) are thought to play a role in infection-associated inflammation at the maternal-fetal interface. Therefore, the objective of this study was to characterize the cytokine profile and antiviral response in human FMs exposed to viral dsRNA, which activates TLR3, and viral ssRNA, which activates TLR8; and to determine the mechanisms involved. The viral dsRNA analog, Poly(I:C), induced up-regulated secretion of MIP-1α, MIP-1β, RANTES and TNF-α, and down-regulated interleukin (IL)-2 and VEGF secretion. In contrast, viral ssRNA induced a broader panel of cytokines in the FMs by up-regulating the secretion of IL-1β, IL-2, IL-6, G-CSF, MCP-1, MIP-1α, MIP-1β, RANTES, TNF-α and GRO-α. Using inhibitory peptides against TLR adapter proteins, FM secretion of MIP-1β and RANTES in response to Poly(I:C) was MyD88 dependent; MIP-1α secretion was dependent on MyD88 and TRIF; and TNF-α production was independent of MyD88 and TRIF. Viral ssRNA-induced FM secretion of IL-1β, IL-2, IL-6, G-CSF, MIP-1α, RANTES and GRO-α was dependent on MyD88 and TRIF; MIP-1β was dependent upon TRIF, but not MyD88; and TNF-α and MCP-1 secretion was dependent on neither. Poly(I:C), but not ssRNA, induced an FM antiviral response by up-regulating the expression of IFNβ, myxovirus-resistance A, 2',5'-oligoadenylate synthetase and apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G. These findings demonstrate that human FMs respond to two viral signatures by generating distinct inflammatory cytokine/chemokine profiles and antiviral responses through different mechanisms.

Syncytiotrophoblast vesicles show altered micro-RNA and haemoglobin content after ex-vivo perfusion of placentas with haemoglobin to mimic preeclampsia

Background

Cell-free foetal haemoglobin (HbF) has been shown to play a role in the pathology of preeclampsia (PE). In the present study, we aimed to further characterize the harmful effects of extracellular free haemoglobin (Hb) on the placenta. In particular, we investigated whether cell-free Hb affects the release of placental syncytiotrophoblast vesicles (STBMs) and their micro-RNA content.

Methods

The dual ex-vivo perfusion system was used to perfuse isolated cotyledons from human placenta, with medium alone (control) or supplemented with cell-free Hb. Perfusion medium from the maternal side of the placenta was collected at the end of all perfusion phases. The STBMs were isolated using ultra-centrifugation, at 10,000×g and 150,000×g (referred to as 10K and 150K STBMs). The STBMs were characterized using the nanoparticle tracking analysis, identification of surface markers and transmission electron microscopy. RNA was extracted and nine different micro-RNAs, related to hypoxia, PE and Hb synthesis, were selected for analysis by quantitative PCR.

Results

All micro-RNAs investigated were present in the STBMs. Mir-517a, mir-141 and mir-517b were down regulated after Hb perfusion in the 10K STBMs. Furthermore, Hb was shown to be carried by the STBMs.

Conclusion

This study showed that Hb perfusion can alter the micro-RNA content of released STBMs. Of particular interest is the alteration of two placenta specific micro-RNAs; mir-517a and mir-517b. We have also seen that STBMs may function as carriers of Hb into the maternal circulation.

Human fetal membranes generate distinct cytokine profiles in response to bacterial Toll-like receptor and nod-like receptor agonists

Bacterial infection-associated inflammation is thought to be a major cause of preterm premature rupture of membranes. Proinflammatory cytokines, such as interleukin 1B (IL1B), can weaken fetal membranes (FM) by upregulating matrix metalloproteinases and inducing apoptosis. The mechanism by which infection leads to inflammation at the maternal-fetal interface and subsequent preterm birth is thought to involve innate immune pattern recognition receptors (PRR), such as the Toll-like receptors (TLR) and Nod-like receptors (NLR), which recognize pathogen-associated molecular patterns (PAMPs). The objective of this study was to determine the cytokine profile generated by FMs in response to the bacterial TLR and NLR agonists peptidoglycan (PDG; TLR2), lipopolysaccharide (LPS; TLR4), flagellin (TLR5), CpG ODN (TLR9), iE-DAP (Nod1), and MDP (Nod2). PDG, LPS, flagellin, iE-DAP, and MDP triggered FMs to generate an inflammatory response, but the cytokine profiles were distinct for each TLR and NLR agonist, and only IL1B and RANTES were commonly upregulated in response to all five PAMPs. CpG ODN, in contrast, had a mild stimulatory effect only on MCP-1 and primarily downregulated basal FM cytokine production. IL1B secretion induced by PDG, LPS, flagellin, iE-DAP, and MDP was associated with its processing. Furthermore, FM IL1B secretion in response to TLR2, TLR4, and TLR5 activation was caspase 1-dependent, whereas Nod1 and Nod2 induced IL1B secretion independent of caspase 1. These findings demonstrate that FMs respond to different bacterial TLR and NLR PAMPs by generating distinct inflammatory cytokine profiles through distinct mechanisms that are specific to the innate immune PRR activated.

In vivo and in vitro evidence for placental DNA damage in preeclampsia

Preeclampsia (PE) is an idiopathic multisystem disease affecting 5–7% of pregnant women. Placental oxidative stress is a characteristic feature of PE and occurs when the production of reactive oxygen species (ROS) within the placenta overwhelms the intrinsic anti-oxidant defenses. We hypothesize that excessive oxidative DNA damage at the fetal-maternal interface coupled with a defective DNA damage/repair response is causally related to PE. Here we demonstrate that γH2AX (a sensitive marker of DNA damage) is expressed in the maternal decidua but not trophoblast of normal placentas, and that expression is significantly higher in PE placental tissues in vivo. Using primary in vitro cultures of maternal decidual stromal cells (DSCs) and fetal cytotrophoblast cells (CTs), we show an increase in γH2AX foci in DSCs cultured with vs without H₂O₂ (70.6% vs 11.6%; P<0.0001) or under hypoxia-reperfusion vs normoxia (20- vs 3-fold; P = 0.01); no foci were seen in CTs. We further demonstrate that Base Excision Repair (BER) intermediates are significantly increased in DSCs (not CTs) under these same conditions. Our data show that DNA damage is significantly more common in PE placentas, and that this DNA damage is localized to the maternal and not fetal side of the placenta. CTs may be selectively resistant to DNA damage in an effort to protect the fetus.

Elevated fetal adipsin/acylation-stimulating protein (ASP) in obese pregnancy: novel placental secretion via Hofbauer cells

CONTEXT AND OBJECTIVE

Obesity in pregnancy is associated with increased risks of obesity in the offspring. We investigated the relationship between obesity in pregnancy and circulating maternal and fetal levels of adipose tissue-derived factors adipsin and acylation stimulating protein (ASP) in lean and obese mothers.

DESIGN

Paired peripheral and cord blood samples were taken. Paired fat and placenta tissue were taken for explant culture. Media were assayed for secreted adipsin and ASP. Clinical parameters assayed included fasting insulin, glucose, and adipsin.

SETTING

The study was conducted at a university hospital maternity unit.

PATIENTS

Patients included 35 lean [body mass index (BMI) 19-25 kg/m(2), mean age 32 years and 39 obese (BMI) > 30 kg/m(2), mean age 32.49 years] pregnant Caucasian women, delivered by cesarean section at term.

MAIN OUTCOME MEASURE

Identification of placental macrophages [Hofbauer cells (HBCs)], as a source of adipsin and ASP was determined.

RESULTS

HBCs secreted both adipsin and ASP. Cord levels of adipsin (1663.78 ± 52.76 pg/mL) and ASP (354.48 ± 17.17 ng/mL) were significantly elevated in the offspring of obese mothers compared with their lean controls [1354.66 ± 33.87 pg/mL and 302.63 ± 14.98 ng/mL, respectively (P < .05 for both)]. Placentae from obese mothers released significantly more adipsin and ASP than placentae from lean mothers [546.0 ± 44 pg/mL · g vs 284.56 ± 43 pg/mL · g and 5485.75 ± 163.32 ng/mL · g vs 2399.16 ± 181.83 ng/mL · g, respectively (P < .05 for both)]. Circulating fetal adipsin and ASP positively correlated with maternal BMI (r = 0.611, P < .0001, and r = 0.391, P < .05, respectively). Fetal adipsin correlated positively with maternal (r = 0.482, P < .01) and fetal homeostasis model assessment of insulin resistance (r = 0.465, P < .01).

CONCLUSIONS

We demonstrate novel secretion of adipsin and ASP by placental HBCs.

Viral infection of the pregnant cervix predisposes to ascending bacterial infection

Preterm birth is the major cause of neonatal mortality and morbidity, and bacterial infections that ascend from the lower female reproductive tract are the most common route of uterine infection leading to preterm birth. The uterus and growing fetus are protected from ascending infection by the cervix, which controls and limits microbial access by the production of mucus, cytokines, and antimicrobial peptides. If this barrier is compromised, bacteria may enter the uterine cavity, leading to preterm birth. Using a mouse model, we demonstrate, to our knowledge for the first time, that viral infection of the cervix during pregnancy reduces the capacity of the female reproductive tract to prevent bacterial infection of the uterus. This is due to differences in susceptibility of the cervix to infection by virus during pregnancy and the associated changes in TLR and antimicrobial peptide expression and function. We suggest that preterm labor is a polymicrobial disease, which requires a multifactorial approach for its prevention and treatment.

Effect of culture conditions on the phenotype of THP-1 monocyte cell line

PROBLEM

Macrophage function has many implications in a variety of diseases. Understanding their biology becomes imperative when trying to elucidate immune cell interactions with their environment, and in vitro cell lines allow researchers to manipulate these interactions. A common cell line used is THP-1, a promyeloid cell line suggestive to outside factors, and therefore sensitive to culture conditions. In this study, we describe how culture conditions can alter THP-1 morphology and in turn affect their response to differentiation stimuli.

METHOD OF STUDY

THP-1 cells were cultured in two conditions and treated with phorbol 12-myristate 13-acetate (PMA) or MCSF. CD14 surface expression was determined by flow cytometry and cytokine/chemokine production determined by multiplex analysis.

RESULTS

Culture conditions of THP-1 affect their response to PMA. Highly confluent THP-1 cells differentiate into a heterogeneous population responsive to PMA as seen by an increase in CD14 expression. However, these cells, cultured in low confluence, remain as a homogenous population and do not gain CD14. Additionally, there are major differences in the constitutive cytokine profile.

CONCLUSION

We demonstrate that the culture conditions of THP-1 cells can alter their response PMA. This suggests that culture techniques may account for the discrepancy in the literature of both basal THP-1 phenotype and their response to PMA.

Decreased levels of folate receptor-β and reduced numbers of fetal macrophages (Hofbauer cells) in placentas from pregnancies with severe pre-eclampsia

PROBLEM

Pre-eclampsia (PE), a pregnancy complication of unknown etiology, is a major cause of maternal and fetal mortality and morbidity. Previous studies have described placental genes that are up-regulated in expression in PE, but few studies have addressed placental gene suppression in this syndrome.

METHOD OF STUDY

Gene profiling and quantitative reverse transcription PCR (qRTPCR) analyses were used to identify genes down-regulated in placentas from women with severe preterm PE compared with gestational age-matched normotensive controls with spontaneous preterm birth (sPTB). Western blotting and immunohistochemistry were used to evaluate levels and patterns of cell type-specific protein expression in PE and sPTB group placentas.

RESULTS

Levels of macrophage marker [folate receptor (FR)-β, CD163, and CD68] mRNA and FR-β protein were significantly down-regulated in PE group placentas compared with the sPTB group. Numbers of Hofbauer cells (HBCs, fetal macrophages) and FR-β protein in these cells were reduced in PE group placentas.

CONCLUSION

Severe PE is associated with decreased placental expression of FR-β and a reduction in the number of HBCs. Reduced placental macrophage function is likely to play a key role in the pathophysiology of PE.

Glucocorticoids enhance CD163 expression in placental Hofbauer cells

Periplacental levels of glucocorticoid (GC) peak at parturition, and synthetic GC is administered to women at risk for preterm delivery. However, little is known concerning cell-type-specific effects of GC in placenta. Hofbauer cells (HBCs) are fetal macrophages that are located adjacent to fetal capillaries in placenta. The goal of the current study was to determine whether GC treatment altered HBC gene expression and function. Western blotting and flow cytometry revealed CD163 and folate receptor-β (FR-β), markers of antiinflammatory M2 macrophages, were specifically expressed by primary cultures of HBCs immunopurified from human term placentas. GC receptor mRNA and protein levels were higher in HBCs compared with placental fibroblasts. Treatment of HBCs with cortisol or dexamethasone (DEX) markedly and specifically enhanced CD163 protein and mRNA levels, whereas expression of FR-β and CD68 were largely unresponsive to GC treatment. DEX treatment also increased hemoglobin uptake by HBCs, evidence of enhanced HBC function. The level of CD163 mRNA, but not FR-β or CD68 mRNA, was stimulated in placental explant cultures by DEX treatment, and increased CD163/FR-β and CD163/CD68 mRNA ratios sensitively reflected the response to GC. Maternal GC administration was associated with increased CD163/FR-β and CD163/CD68 mRNA ratios in placentas from women with spontaneous preterm birth. In conclusion, in vitro studies indicated that GC treatment specifically up-regulated CD163 expression in HBCs and enhanced HBC function. In addition, the observed alterations in patterns of expression of macrophage marker genes associated with maternal GC administration suggest that HBCs are in vivo targets of GC action.

Cutting-edge report: TLR10 plays a role in mediating bacterial peptidoglycan-induced trophoblast apoptosis

PROBLEM

There is a strong correlation between intrauterine bacterial infection and preterm labor. While inflammation is a common mechanism, certain pathogens may trigger placental apoptosis. TLR2 activation by gram-positive bacterial peptidoglycan (PDG) induces first-trimester trophoblast apoptosis and decreased IL-6 secretion. This is dependent upon the presence of TLR1 and the absence of TLR6 and both TLR2 coreceptors. As TLR10 is also a TLR2 coreceptor, the objective of this study was to determine its expression and function in the trophoblast.

METHOD OF STUDY

First-and third-trimester human placental tissue and isolated trophoblast were evaluated for TLR10 expression. A first-trimester human trophoblast cell line stably transfected with a TLR10 dominant negative (TLR10-DN) or vector control was treated with or without PDG and analyzed for apoptosis and IL-6.

RESULTS

TLR10 was expressed by trophoblasts during the first and third trimesters of pregnancy. PDG-induced trophoblast caspase-3 activity was inhibited by the presence of the TLR10-DN. The presence of the TLR10-DN had no effect on PDG reduction in trophoblast IL-6 secretion.

CONCLUSION

This study demonstrates that trophoblast TLR10 plays a role in promoting apoptosis triggered by gram-positive bacterial components and suggests that TLR10 may regulate the balance between trophoblast survival and cell death.

Lipopolysaccharide appears to activate human endometrial endothelial cells through TLR-4-dependent and TLR-4-independent mechanisms

PROBLEM

Uterine innate immunity remains poorly characterized, and while endometrial endothelial cells are known to express Toll-like receptors (TLRs), little is known about their function in these cells. The present study evaluated the effect of Gram-negative bacterial lipopolysaccharide (LPS) on human endometrial endothelial cell (HEECs) cytokine secretion and tissue factor expression, and the role of TLR-4 in these responses.

METHODS

Human endometrial endothelial cells were treated with or without LPS ± LPS-RS, a TLR-4 antagonist, via the binding of MD-2. After 24 hr, cell-free supernatants were evaluated for cytokines by multiplex analysis and cell lysates were analyzed for tissue factor expression by Western blot.

RESULTS

Treatment of HEECs with LPS significantly upregulated the secretion of IL-6, IL-8, and G-CSF, and this was prevented by LPS-RS. LPS also induced tissue factor expression by the HEECs; however, this was unaffected by LPS-RS.

CONCLUSION

These findings suggest that TLR-4 is functional in HEECs and its activation by bacterial LPS induces a specific cytokine/chemokine response. However, bacterial LPS also induced tissue factor expression in what seemed to be a TLR-4-independent fashion, suggesting that this bacterial component can act on the HEECs through TLR-4-dependent and TLR-4-independent pathways. These findings indicate that endometrial endothelial cells may play an active role in uterine innate immunity.

Toll-like receptor 4 expression in decidual cells and interstitial trophoblasts across human pregnancy

PROBLEM

Toll-like receptor-4 (TLR-4) protects against Gram-negative bacteria expressed lipopolysaccharide and 'danger signals' from injured or dying cells. Although decidual cells (DCs) and interstitial trophoblasts (ITs) are in close contact, TLR-4 has been studied extensively only in ITs.

METHOD OF STUDY

Formalin-fixed, paraffin-embedded serial sections of endometrium in follicular and luteal phases and deciduas from first and second trimester elective terminations and third trimester normal deliveries were immunostained for TLR-4, trophoblast-specific cytokeratin, and DC-specific vimentin. HSCORE assessed TLR-4 immunostaining in DCs versus ITs.

RESULTS

TLR-4 HSCORES were significantly higher in: (i) first trimester DCs than luteal phase pre-decidual stromal cells; (ii) first and third versus second trimester DCs, but similar between third trimester deciduas parietalis and basalis; (iii) first versus second trimester ITs; (iv) DCs versus ITs across gestation.

CONCLUSION

Higher TLR-4 in DCs than ITs suggests DCs as primary targets for Gram-negative bacteria and/or inflammation-related danger signals.

Hydroxychloroquine reduces binding of antiphospholipid antibodies to syncytiotrophoblasts and restores annexin A5 expression

OBJECTIVE

Antibody-mediated disruption of the annexin A5 anticoagulant shield has been posited to be a thrombogenic mechanism in the antiphospholipid syndrome. We recently showed that the antimalarial drug, hydroxychloroquine, dissociates antiphospholipid immune complexes and restores annexin A5 binding to planar phospholipid bilayer. Using quantitative immunoassays, we demonstrated similar effects on BeWo trophoblasts. We therefore, investigated the effects of the drug on localization of annexin A5 in primary cultures of human placental syncytiotrophoblasts.

STUDY DESIGN

Laser confocal microscopy with computer-based morphometric analysis was used to localize annexin A5 and antiphospholipid antibodies on syncytiotrophoblasts exposed to polyclonal and monoclonal antiphospholipid and control immunoglobulin-Gs.

RESULTS

Hydroxychloroquine reversed the effects of the antiphospholipid antibodies on the syncytiotrophoblasts by markedly reducing immunoglobulin-G binding and restoring annexin A5 expression.

CONCLUSION

These results provide the first morphologic evidence for this effect of hydroxychloroquine on human placental syncytiotrophoblasts and support the possibility of novel treatments that target antiphospholipid antibody binding.

Uric acid induces trophoblast IL-1β production via the inflammasome: implications for the pathogenesis of preeclampsia

PROBLEM

Preeclampsia is associated with hyperuricemia, which correlates with the disease severity. Levels of circulating uric acid increase before the clinical manifestations, suggesting that they may be causally related. Uric acid, or monosodium urate (MSU), activates the Nod-like receptor, Nalp3, leading to inflammasome activation and IL-1β processing. Because preeclampsia is associated with placental immune⁄ inflammatory dysregulation, we sought to determine in the trophoblast, the presence of the Nalp3 inflammasome, and the effect of MSU on its activation.

METHOD OF STUDY

Isolated first- and third-trimester trophoblasts were assessed for expression of the inflammasome components, Nalp1, Nalp3, and ASC. First-trimester trophoblast cells were incubated with or without MSU, and after which, IL-1β secretion and processing and caspase-1 activation were determined.

RESULTS

Trophoblast cells expressed Nalp1, Nalp3, and ASC under basal conditions. Following incubation with MSU, first-trimester trophoblast IL-1β secretion was upregulated. This correlated with increased expression levels of active IL-1β and active caspase-1. ASC knockdown reduced MSU-induced IL-1β secretion.

CONCLUSION

These findings demonstrate that uric acid activates the inflammasome in the trophoblast, leading to IL-1β production. This may provide a novel mechanism for the induction of inflammation at the maternal–fetal interface leading to placental dysfunction and adverse pregnancy outcome, including preeclampsia.