Molecular phenotype of monocytes at the maternal-fetal interface.

OBJECTIVE: The purpose of this study was to gain insight into the pathways that are associated with inflammation at the maternal-fetal interface. This study examined the molecular characteristics of monocytes that were derived from the maternal circulation and the placenta of obese women. STUDY DESIGN: Mononuclear cells were isolated from placenta, venous maternal, and umbilical cord blood at term delivery; activated monocytes were separated with CD14 immunoselection. The genotype and expression pattern of the monocytes were analyzed by microarray and real-time reverse transcriptase-polymerase chain reaction. RESULTS: The transcriptome of the maternal blood and placental CD14 monocytes exhibited 73% homology, with 10% (1800 common genes) differentially expressed. Genes for immune sensing and regulation, matrix remodeling, and lipid metabolism were enhanced 2-2006 fold in placenta, compared with maternal monocytes. The CD14 placental monocytes exhibited a maternal genotype (9% DYS14 expression) as opposed to the fetal genotype (90% DYS14 expression) of the trophoblast cells. CONCLUSION: CD14 monocytes from the maternal blood and the placenta share strong phenotypic and genotypic similarities with an enhanced inflammatory pattern in the placenta. The functional traits of the CD14 blood and placental monocytes suggest that they both contribute to propagation of inflammation at the maternal-fetal interface.

Pregravid obesity associates with increased maternal endotoxemia and metabolic inflammation.

Obese pregnant women develop severe insulin resistance and enhanced systemic and placental inflammation, suggesting associated modifications of endocrine and immune functions. Activation of innate immunity by endotoxins/lipopolysaccharides (LPS) has been proposed as a mechanism for enhancing metabolic alterations in disorders with insulin resistance. The aim of this study was to characterize the immune responses developed by the adipose tissue (AT) and their potential links to maternal endotoxemia in pregnancy with obesity. Blood and subcutaneous abdominal AT were obtained from 120 lean and obese women (term pregnancy) recruited at delivery. Gene expression was assessed in AT and stromal vascular cells isolated from a subset of 24 subjects from the same cohort. Doubling of plasma endotoxin concentrations indicated subclinical endotoxemia in obese compared with lean women. This was associated with significant increase in systemic C-reactive protein and interleukin-6 (IL-6) but not tumor necrosis factor-α (TNF-α) concentrations. AT inflammation was characterized by accumulation of CD68(+) macrophages with a threefold increased gene expression of the macrophage markers CD68, EMR1, and CD14. Gene expression for cytokines IL-6, TNF-α, IL-8, and monocyte chemotactic protein-1 (MCP1) and for LPS-sensing CD14, toll-like receptor 4 (TLR4), translocating chain-associated membrane protein 2 was 2.5-5-fold higher in stromal cells of obese compared to lean. LPS-treated cultured stromal cells of obese women expressed a 5-16-fold stimulation of the same cytokines upregulated in vivo. Our data demonstrate that subclinical endotoxemia is associated with systemic and AT inflammation in obese pregnant women. Recognition of bacterial pathogens may contribute to the combined dysfunction of innate immunity and the metabolic systems in AT.

CD34+ cells in maternal placental blood are mainly fetal in origin and express endothelial markers.

Fetal CD34+ cells enter the maternal circulation during pregnancy and may persist for decades. These cells are usually depicted as hematopoietic stem/progenitor cells. Our objective was to further determine the phenotype of fetal chimeric CD34+ cells in placental maternal blood from the intervillous space (IVS). Human healthy term placentas were analyzed (n=9). All fetuses were male. CD34+ cells were identified in the IVS and further characterized as fetal or maternal using X and Y chromosome fluorescence in situ hybridization. The phenotype of fetal cells was further analyzed using anti-CD117 (c-kit), anti-CD133, anti-CD31, anti-von Willebrand factor (vWF), anti-vimentin, anti-CD45 and anti-cytokeratin (CK) antibodies. We used preeclamptic placentas of male (n=3) and healthy placentas of female fetuses (n=3) as controls. As expected fetal cells were easily identified in the IVS and significantly increased in cases of preeclampsia. Most CD34+ cells in the IVS were of fetal origin (90%) and were not surrounded by CK staining further showing that they were not in fetal trophoblastic villi. Similarly, about 40% of CD31+ and 6% of vimentin+ cells in the IVS were fetal in origin. No CD117+ or CD133+ fetal cells were found in the IVS of examined placentas. Besides, all the CD34+ cells identified in the IVS were co-labeled with vWF or CD31, suggesting their endothelial origin. These results suggest that most CD34+ cells in maternal placental blood at term are fetal in origin from endothelial and not hematopoietic lineages.

Doppler and immunohistochemical evaluation of decidual spiral arteries in early pregnancy.

OBJECTIVE: The purpose of this study was to estimate spiral artery subchorionic flow at 8-11 gestational weeks (GW) by Doppler ultrasound and then to analyze these vessels in the decidua basalis using histologic, morphometric and immunohistochemical analyses. METHODS: Subchorionic spiral arteries were evaluated in 5 women scheduled for aspiration at 8-11 GW. Flow velocity waveforms were sought using color and pulsed Doppler, and the diastolic/systolic (D/S) index was calculated. Transcervical biopsy specimens and aspiration products were thoroughly examined to investigate the structure of the spiral artery at the implantation site using cytotrophoblastic and arterial smooth muscle cell immunohistochemical markers (anti-cytokeratin 7 and anti-actin monoclonal antibodies). Spiral artery cross-sectional inner areas were measured and compared with the D/S index in each case. RESULTS: Low-impedance pulsatile flow could be detected below the trophoblastic ring in all cases. Complete obstruction of a spiral artery lumen was never observed and cytotrophoblastic cells were incorporated into the vessel wall starting from the perivascular cuff. CONCLUSION: Both techniques evidenced that decidual spiral arteries in the placental bed are not completely obstructed at 8-11 GW.

Erythroblasts secrete the nonclassical HLA-G molecule from primitive to definitive hematopoiesis.

The initial steps of primitive hematopoiesis and endothelial vascular formation in the human embryo remain to be defined. Here, we report the identification of a novel marker, namely the nonclassical HLA-G class I molecule, which targets both primitive erythroid cells of the yolk sac and endothelial cells from developing vessels. Moreover, HLA-G was present in its soluble form in the erythropoietic lineage in all organs sustaining primitive to definitive erythropoiesis (ie, aorta-gonad-mesonephros, liver, spleen, and bone marrow). The alternatively spliced transcript coding the soluble HLA-G5 molecule was detected in erythroid cells. The corresponding intron 4-retaining 37-kDa HLA-G5 isoform was secreted from the erythroid progenitor stage to the reticulocyte but was lost in mature erythrocytes and in endothelial cells from differentiated vessels. This study constitutes the first description of an HLA class I antigen expression on the primitive erythroid lineage and provides a way of seeking both primitive and definitive erythropoiesis using HLA-G5. This new marker, previously known by its immunotolerogeneic properties, may be involved in erythroid differentiation, angiogenesis, or both.

Pathophysiology of preeclampsia: links with implantation disorders.

The phenomenon of implantation anchors the embryo into the uterine wall and produces a hemochorial placenta that maintains the pregnancy and fetal growth. Implantation and placentation are intimately linked and cannot be dissociated either in time or in space. Preeclampsia is characterized by hypertension and proteinuria. It is secondary to an anomaly of the invasion of the uterine spiral arteries by extra-villous cytotrophoblast cells, associated with local disruptions of vascular tone, of immunological balance and inflammatory status, and sometimes with genetic predispositions. Preeclampsia is a disease of early pregnancy, a form of incomplete spontaneous abortion, but is expressed late in pregnancy. Aspirin may play a favorable role in implantation which is related to the genesis of preeclampsia and some cases of intra-uterine growth restriction. The most important points in obtaining a preventive effect from low-dose aspirin during the pregnancy are early treatment (before 13 weeks of gestation) and the prescription of a sufficient dose (more than 100 mg per day).

[The human placenta and its pathologies: focus on oxygen]. / Le placenta humain et ses pathologies: l'oxygène en question.

At the time of placentation, the conceptus surrounds itself with a trophoblastic layer where the villous tree develops and the uteroplacental circulation takes place. Analysis of the modalities of maternal blood entrance demonstrated a physiological hypoxia ending with the first trimester of pregnancy. Moreover, cultures of first trimester villous explants have shown the role of oxygen in extravillous cytotrophoblast proliferation, decidual invasion and spiral artery remodeling. Oxygen appears to be a key factor controlling the mechanism of placentation by regulating the transcription of several genes, such as VEGF (vascular endothelial growth factor), leptin, etc. These genes are turned on or off as a function of oxygen partial pressure via an oxygen sensor. Oxygen is now considered to be implicated in the development of several pathologies of pregnancy. It is involved at different steps in the cascade of events leading to preeclampsia. Positive correlations have been observed between oxygen partial pressure and abnormal development of the villous tree in intrauterine growth retardation, and in maternal anemia or pregnancy in altitude.

TNF-alpha is a predictor of insulin resistance in human pregnancy.

Historically, insulin resistance during pregnancy has been ascribed to increased production of placental hormones and cortisol. The purpose of this study was to test this hypothesis by correlating the longitudinal changes in insulin sensitivity during pregnancy with changes in placental hormones, cortisol, leptin, and tumor necrosis factor (TNF)-alpha. Insulin resistance was assessed in 15 women (5 with gestational diabetes mellitus [GDM] and 10 with normal glucose tolerance) using the euglycemic-hyperinsulinemic clamp procedure, before pregnancy (pregravid) and during early (12-14 weeks) and late (34-36 weeks) gestation. Body composition, plasma TNF-alpha, leptin, cortisol, and reproductive hormones (human chorionic gonadotropin, estradiol, progesterone, human placental lactogen, and prolactin) were measured in conjunction with the clamps. Placental TNF-alpha was measured in vitro using dually perfused human placental cotyledon from five additional subjects. Compared with pregravid, insulin resistance was evident during late pregnancy in all women (12.4 +/- 1.2 vs. 8.1 +/- 0.8 10(-2) mg. kg(-1) fat-free mass. min(-1). microU(-1). ml(-1)). TNF-alpha, leptin, cortisol, all reproductive hormones, and fat mass were increased in late pregnancy (P < 0.001). In vitro, most of the placental TNF-alpha (94%) was released into the maternal circulation; 6% was released to the fetal side. During late pregnancy, TNF-alpha was inversely correlated with insulin sensitivity (r = -0.69, P < 0.006). Furthermore, among all of the hormonal changes measured in this study, the change in TNF-alpha from pregravid to late pregnancy was the only significant predictor of the change in insulin sensitivity (r = -0.60, P < 0.02). The placental reproductive hormones and cortisol did not correlate with insulin sensitivity in late pregnancy. Multivariate stepwise regression analysis revealed that TNF-alpha was the most significant independent predictor of insulin sensitivity (r = -0.67, P < 0.0001), even after adjustment for fat mass by covariance (r = 0.46, P < 0.01). These observations challenge the view that the classical reproductive hormones are the primary mediators of change in insulin sensitivity during gestation and provide the basis for including TNF-alpha in a new paradigm to explain insulin resistance in pregnancy.