Materno–fetal passage of nutritive and inhalant allergens across placentas of term and pre-term deliveries perfused in vitro

BACKGROUND: The pre- and postnatal environment appears to be of crucial importance for the manifestation of allergic diseases, which often begin during infancy. Although T cell reactivity of fetal origin to a range of common allergens is present in most cord blood samples, the immunological basis remains unclear. OBJECTIVE: In order to test the hypothesis of transplacental allergen transfer we studied double-sided open ex vivo perfusion experiments of isolated placental cotyledons with the nutritive allergens beta-lactoglobulin (BLG) and ovalbumin (OVA) and the inhalant major birch pollen allergen Bet v1. METHODS: Placentas of full-term and pre-term newborns were obtained immediately after delivery to recover functionally active maternal and fetal circulations. Thus, a fetal artery and a fetal vein were cannulated and perfused with pure medium (fetoplacental circulation), whereas the intervillous space of placentas was flushed with allergen containing medium by puncture of the basal plate (maternoplacental circulation). Samples that were collected throughout the perfusion experiment from fetal venous outflow were tested by allergen-specific enzyme-linked immunosorbent assays (ELISA) for the presence of allergens indicative of materno-fetal transplacental passage. RESULTS: We observed transplacental transfer of BLG, OVA and Bet v1 in placentas of term as well as premature deliveries. The respective allergen was readily detectable in fetal effluent at the beginning of the perfusion experiment and allergen levels reached a plateau after about 2 h. The steady state transfer rate of BLG and OVA in term placentas was 0.012% +/- 0.001 and 0.013% +/- 0.001 of total dose, i.e. 130.21 +/- 7.41 ng/mL and 115.83 +/- 6.07 ng/mL, respectively. The observed transfer rate of Bet v1 after 2h of perfusion was 0.155% +/- 0.034 of total dose, that is 2.41 +/- 1.36 ng/mL. Transplacentally transferred concentration of BLG and OVA in pre-term placentas increased continuously throughout perfusion time from 5.32 +/- 0.92 ng/mL at 1 min to 87.53 +/- 21.93 ng/mL at 120 min and 1.35 +/- 0.31 ng/mL at 1 min to 112.87 +/- 5.25 ng/mL at 150 min, respectively. CONCLUSION: Allergen-specific cord blood reactivity may be attributed to low levels of allergens crossing the human placenta and providing the fetus with the necessary stimulus for T cell priming.     

Dose-dependent and preterm- accentuated diaplacental transport of nutritive allergens in vitro

OBJECTIVE: The mechanisms by which nutritive allergens are transported from mother to fetus and the ensuing immunological response are incompletely understood. We investigated the role of different allergen concentrations in influencing the diaplacental allergen transport in preterm and term placentas. METHOD: Twenty-seven human term placentas and 12 preterm placentas were dually perfused in vitro for up to 4 h by adding alternately two different nutritive allergens, beta-lactoglobulin (BLG) or ovalbumin (OVA), at four different allergen concentrations (0.02, 0.2, 2 and 20 mg/ml) to the maternal perfusate medium. Allergen concentrations in fetal venous outflow samples collected during perfusion were measured by using specific ELISAs. RESULTS: Perfusion of increasing allergen concentrations via the maternal circulation resulted in a concentration-dependent increase of fetal allergen uptake in all term and preterm placentas. A mean maternal-to-fetal ratio of 20,000/1 and 3,000/1 for BLG, and 40,000/1 and 5,000/1 for OVA was found in term and preterm placentas, respectively. Preterm placentas (27-36 weeks of gestation) were found to favor the diaplacental passage of nutritive allergens compared with placentas at term (>36 weeks of gestation). CONCLUSION: Maternal-to-fetal allergen transport occurs in a dose-dependent and molecular weight-dependent manner with clear accentuation in preterm placentas.     

Most of diaplacentally transferred allergen is retained in the placenta

BACKGROUND: Transplacental transfer of nutritive and inhalant allergens has been described being potentially responsible for a series of events leading to antigen-specific immune responses in the fetus. As such, cord blood T cell responses appear ubiquitously. However, studies failed to reveal a consistent dose-response relationship between antenatal allergen exposure and allergen-specific cellular reactivity in cord blood. OBJECTIVE: To examine the transfer process of allergens (ovalbumin (OVA), beta-lactoglobulin (BLG), birch pollen allergen Bet v1) in placental tissue (BeWo cell line, ex vivo placenta model). METHODS: The choriocarcinoma cell line BeWo was used to study the allergen uptake and transfer experiments in vitro. In the ex vivo placenta model the contribution of different placental compartments was evaluated. For this, immuno-histochemistry, immuno-electronmicroscopy and ELISA techniques were applied using monoclonal antibodies to Bet v1, OVA and -BLG. RESULTS: In vitro transfer studies on a BeWo cell-layer revealed an intracellular allergen uptake and a trans-trophoblastic allergen transfer, which was temperature- and concentration dependent, pH sensitive and asymmetric. Allergen-specific staining of placental tissue after allergen perfusion (BLG) demonstrated bulk of the allergen in the syncytio-trophoblastic cell layer and minor staining in the villous stroma and in the endothelium of fetal vessels. Immunogold staining revealed an accumulation of the perfused allergen in the trophoblastic basement membrane. CONCLUSION: In vitro/ex vivo trans-trophoblastic and trans-placental allergen transfer is shown with an accumulation of most of the allergen in placental tissues, potentially explaining the missing direct dose-response relationship between prenatal (maternal) allergen exposure and allergen-specific cellular reactivity in cord blood.     

Cord blood leucocytes/basophils produce and release sulfidoleucotrienes in response to allergen stimulation

BACKGROUND: Leucocyte-derived sulfidoleucotrienes (SLT) from children and adults can be detected in vitro in response to specific allergen stimulation, a mechanism thought to require the presence of allergen-specific immunoglobulin (Ig)E antibodies on the surface of basophils. It is unknown whether this mechanism is functional in cord blood basophils. OBJECTIVE: We studied the in vitro SLT-release of leucocytes in response to allergen and anti-IgE stimulation in term newborns and children with allergic diseases. METHODS: Cord blood from randomly selected term newborns were analysed for total IgE-antibodies and in vitro SLT-release in response to allergen and anti-IgE stimulation. Children from an allergy outpatient clinic were used as the control group. The Cellular Allergen Stimulation Test (CAST) was used as read-out system. Allergen stimulation was performed with an allergen-mix containing 21 nutritive and inhalant allergens. RESULTS: Peripheral blood leucocytes/basophils derived from allergic children (n = 56; median SLT release 1049 pg/mL) were more responsive to anti-IgE stimulation as cord blood leucocytes/basophils (n = 104; median 419 pg/mL P < 0.0001). In response to stimulation with an allergen-mix, the two groups did not differ significantly from each other. Only SLT-releasability in response to anti-IgE showed a correlation with cord blood IgE. CONCLUSIONS: Sulfidoleucotriene-release of cord blood basophils is functional in response to allergens. It appears possible that cord blood basophils are armed with allergen-specific IgE-antibodies though not detectable in serum. Therefore, cord blood SLT-release may indirectly reflect prenatal priming with allergens with subsequent production of allergen-specific IgE.     

Transplacental priming of the human immune system with environmental allergens can occur early in gestation

BACKGROUND: Allergen-specific T cells play an important role in the allergic immune response to various environmental allergens. In vitro studies have shown that T-cell responses to these allergens do occur prenatally. Some allergens (milk proteins) appear to lead more often to fetal T-cell priming than others (house dust mite allergen, ovalbumin, and birch and grass pollen allergens). OBJECTIVE: We sought to determine the window of opportunity for prenatal T-cell priming with inhalant and nutritive allergens. METHODS: The T-cell reactivity of cord blood cells derived through cordocentesis from unborn (n = 62) and term babies (n = 114) in response to inhalant allergens (birch pollen major allergen, recombinant Bet v 1, and timothy grass major allergen, recombinant Phl p 1) was investigated. RESULTS: The results demonstrate that allergen-specific T-cell reactivity is as common in preterm as in term infants (Bet v 1, 8% and 5%, respectively; Phl p 1, 20% and 25%, respectively). CONCLUSIONS: Our data support the hypothesis that differential handling of the allergenic proteins by the feto-placental barrier and possibly by antigen-presenting cells may directly modulate the ensuing T-cell immune response.     

Cytokine responses to allergens during the first 2 years of life in Estonian and Swedish children

BACKGROUND: The prevalence of atopic disease among children in the formerly socialist countries in Europe, with a life style similar to that prevailing in Western Europe 30-40 years ago, is low, whereas there has been a pronounced increase in industrialized countries over the last decades. The environment during infancy influences the risk of developing allergy for many years, perhaps even for life. OBJECTIVE: To investigate the development of allergen-specific cytokine responses during the first 2 years of life in two geographically adjacent countries with marked differences in living conditions and incidence of atopic diseases, i.e. Estonia and Sweden. METHODS: The development of immune responses to food (beta-lactoglobulin (BLG) and ovalbumin (OVA)) and inhalant (cat and birch) allergens was studied from birth up to the age of 2 years in 30 Estonian and 76 Swedish infants. Clinical investigation and skin prick tests were performed and blood samples were obtained at birth and at 3, 6, 12 and 24 months. RESULTS: The levels of IL-5, IL-10 and IL-13 secreted by peripheral blood mononuclear cells stimulated with BLG, OVA and cat allergen in Estonian and Swedish infants declined during the first 3 months of life. All cytokines then progressively increased in the Swedish infants, indicating the replacement of non-specifically responding immature cord blood T cells with specific T memory cells, which are primed postnatally. The resurgence of allergen-specific responses in the Estonian infants was less marked. These differences were particularly notable for birch-specific T cell responses, which correlated with development of atopic disease in the Swedish children. CONCLUSIONS: The development of specific T cell memory to food and inhalant allergens during the first 2 years of life differs between infants living in Sweden and Estonia, and mirrors the disparate patterns of expression of allergic disease which subsequently develops in the respective populations.     

Effects of maternal allergen-specific IgG in cord blood on early postnatal development of allergen-specific T-cell immunity

BACKGROUND: A wide body of epidemiologic evidence indicates that as yet unknown maternal factor(s) can influence susceptibility to allergic disease in the offspring. It is also well established that the induction of allergen-specific T-cell memory is frequently initiated in utero, and it is likely that maternal factors exert their influence during this period. METHODS: This study examines the relationship between maternally derived allergen-specific IgG subclass antibodies and cellular immune responses (lymphoproliferation and cytokine production) against the same allergens in 49 subjects tested at birth and at 2 years of age. Polyclonal production of the Th1 cytokine IFN-gamma was also examined in the cord-blood samples. RESULTS: At birth, there were positive correlations between both house-dust mite (HDM)- and ovalbumin (OVA)-specific IgG subclass levels in cord blood, maternal atopy, and the magnitude of perinatal lymphoproliferative responses to respective allergens. Inverse relationships were also observed between cord-blood IgG antibody titres and allergen-specific production of some Th2 cytokines. However, there were no consistent relationships between cord-blood allergen-specific IgG antibodies and subsequent immune responses to allergens when the same subjects were retested at 2 years of age. An inverse relationship was observed between maternal history of atopy and perinatal IFN-gamma production capacity. CONCLUSIONS: Our results suggest that transplacental transfer of allergen-specific IgG antibody is unlikely to be a major mechanism for maternal regulation of allergen-specific immunity in infancy. An alternative possibility is that maternal effects may operate by influencing IFN-gamma production by T cells in the offspring.     

Distal villous immaturity

Distal villous immaturity (DVI) is a placental phenotype characterized by enlarged distal villi with excessive stroma, hypercellular villous trophoblast, paucity of vasculosyncytial membranes, and a decreased fetoplacental weight ratio. It is predominantly observed in term or near-term placentas and is associated with specific maternal conditions including impaired glucose tolerance, obesity, and excessive pregnancy weight gain. A similar phenotype is observed in placentas with hypercoiling of the umbilical cord. DVI is also occasionally seen in the placentas of preterm infants with idiopathic fetal growth restriction, congenital malformations, and genetic or chromosomal abnormalities. In infants of diabetic mothers, DVI may in part be a consequence of excessive maternal glucose leading to release of fetal insulin and other growth factors that promote excessive placental growth at the expense of villous maturation. Adverse outcomes associated with DVI include intrauterine fetal death (IUFD), fetal growth restriction (FGR), and, more speculatively, late gestational hypoxia and chronic diseases of childhood and later adult life.     

Evidence for allergen‐specific IgE of maternal origin in human placenta

Background: Immunoglobulin E (IgE) has been identified on macrophage‐like cells in the villi of human placenta, irrespective of the serum IgE levels or allergy status of the mother. The origin of placental IgE is debated and it is not known if it is spontaneously produced, so‐called ‘natural IgE’, or if it has any specificity for certain allergens. The aim of this study was to investigate if placental IgE originates from mother or child and to analyse its specificity. Methods: Immunoglobulin E was eluted from placenta by lowering the pH. Total and allergen‐specific IgEs were measured in placenta eluate, maternal and cord blood plasma by means of ImmunoCAP (Phadia AB). The levels of natural antibodies were determined with an anti‐phosphorylcholine (PC) enzyme‐linked immunosorbent assay, as natural IgE has been shown in one previous publication with this assay. Results: Detectable amounts of IgE were eluted from 11/12 full‐term placentas. Natural (anti‐PC) IgE antibodies were detected in low amounts in maternal plasma but not in the placental eluate or in cord blood plasma. There was a significant correlation between the amount of total IgE eluted from placenta and the levels of total IgE in maternal plasma; however, not between maternal and cord blood plasma. Allergen‐specific IgE was only found in placental eluates from mothers with specific IgE towards these allergens. Furthermore, there was a significant correlation between the amount of allergen‐specific IgE eluted from placenta and the levels of allergen‐specific IgE in maternal plasma. Allergen‐specific IgE could not be detected in cord blood. Conclusion: These results suggest a maternal origin of placental IgE, which can be allergen‐specific.     

Isolation and characterization of chorionic mesenchyal stem cells from the placenta

The aim of the study was the isolation and characterization of mesenchymal stem cells from the placental chorion from a genotypical and phenotypical point of view. The placentas included in the study were derived from term pregnancies with a normal evolution. Along with the placentas, umbilical cord blood, maternal and newborn peripheral blood samples were taken. The isolation and culture of chorionic and, incidentally, trophoblastic cells was followed by the determination of markers of the former cells. They expressed proteins and genes characteristic of stem cells. Immunofluorescence and evaluation of gene expression evidenced the pluripotential properties of these cells and also their higher position on the differentiation pathway. HLA expression provides information that might help explain the immunological mechanisms of tolerance between the maternal organism and fetal structures.     

Exposure of the fetus and infant to hens'' egg ovalbumin via the placenta and breast milk in relation to maternal intake of dietary egg

BACKGROUND: Maternally derived allergens may be transferred to the developing infant during pregnancy and lactation. However, it is not known how manipulation of environmental allergen levels might impact on this early-life exposure. OBJECTIVE: To measure dietary egg allergen (ovalbumin (OVA)) in gestation-associated environments, in relation to maternal dietary egg intake. METHOD: OVA was measured by allergen-specific ELISA in maternal blood collected throughout pregnancy, infant blood at birth (umbilical cord) and in breast milk at 3 months post-partum. Samples derived from pregnant women undergoing diagnostic amniocentesis at 16-18 weeks gestation who were not subject to any dietary intervention, and from pregnant women, with personal or partner atopy, randomized to complete dietary egg exclusion or an unmodified healthy diet before 20 weeks gestation as a primary allergy prevention strategy. Maternal dietary egg intake was monitored closely throughout the study period by diary record and serial measurement of OVA-specific immunoglobulin G concentration. RESULTS: Circulating OVA was detected throughout pregnancy in 20% of women and correlated with both presence (P<0.001) and concentration (r=0.754, P<0.001) of infant OVA at birth (umbilical cord). At 3 months post-partum OVA was detected in breast milk samples of 35% women, in higher concentrations than measured in blood. Blood and breast milk OVA were not related to maternal dietary intake or atopic pre-disposition. CONCLUSIONS: Rigorous dietary egg exclusion does not eliminate trans-placental and breast milk egg allergen passage. This early-life exposure could modulate developing immune responses.     

Anesthesia for fetal procedures and surgery.

Many of the anesthetic considerations for fetal procedures and surgery are identical to those for nonobstetric surgery during pregnancy, including concern for maternal safety, avoidance of both teratogenic drugs and fetal asphyxia, and the prevention of preterm labor and delivery. Anesthesia is required for the mother and quite often the fetus to perform many fetal procedures. Fetal procedures and surgery can be divided into subgroups according to their anesthetic requirements. For example: procedures that only require a needle insertion into the uterus but not into the fetus, such as intrauterine infusions; laser surgical photocoagulation of the communicating placental circulation for twin-twin transfusion syndrome (TTTS) and radio-frequency umbilical cord ablation for managing twin reversed arterial perfusion (TRAP), which are not really fetal procedures, rather they are placental or cord procedures; surgical procedures performed directly on the fetus; and the EX-utero Intrapartum Treatment (EXIT) procedure. Anesthetic considerations also depend on other factors, such as the location of the placenta. Unlike maternal surgery, for fetal procedures, the fetus is not an innocent bystander for whom the least anesthetic interference is used. Instead, the fetus can be the primary patient and may benefit from anesthesia, with close monitoring of the anesthetic effects to ensure well-being. Fetal asphyxia, hypoxia, or distress can be most effectively recognized, predicted, and avoided by fetal monitoring. Monitoring is also crucial for assessing the fetal response to corrective maneuvers.     

Fetal and maternal vascular lesions

Many commonly diagnosed disorders of the placenta relate to maternal and fetal blood flow and are thus common in the placentas of infants with adverse perinatal outcomes. Severe uteroplacental vascular disease may lead to extensive placental infarction and villous changes of reduced uteroplacental blood flow, a morphologic feature commonly associated with intrauterine growth restriction and fetal demise. Lesser degrees of villous change are seen in many infants with premature delivery, term, and multiple births resulting in admission to the neonatal intensive care units. Fetal vascular lesions including chorangiosis and fetal thrombotic vasculopathy are two processes that appear to be associated with increased risk of poor outcome.     

Phosphorylation of 3'-azidothymidine in maternal and fetal peripheral blood mononuclear cells during gestation and at term

The present study compared the phosphorylation rate of 3'-azidothymidine (AZT) in isolated maternal and fetal peripheral blood mononuclear cells (PBMCs) with that in amniocytes obtained during gestation and at term. Maternal PBMCs were isolated from venous blood samples obtained from HIV-seronegative pregnant women during delivery. Immediately after delivery, cord blood specimens were collected, and fetal PBMCs were isolated. In a separate set of experiments, maternal and fetal PBMCs and amniocytes were obtained at 17-21 weeks of gestation. The fresh isolated PBMCs and amniocytes were maintained in RPMI 1640 medium until incubation with 10 microM tritiated AZT (10 microCi/mL). Thereafter, methanolic cell extracts were prepared for determination of AZT phosphates by high-performance liquid chromatography. Fetal PBMCs can efficiently convert AZT to its antivirally active metabolite. There were no significant differences after 6 or 12 hours of incubation with AZT between AZT phosphate levels in maternal and fetal PBMCs isolated at term or at 17-21 weeks of gestation: AZT monophosphate was found to be the major metabolite (about 95%). AZT phosphate levels in the amniocytes were up to sevenfold higher than those in the maternal or fetal PBMCs. These results show that during pregnancy and at term, fetal PBMCs-like maternal PBMCs-are able to take up AZT and to efficiently generate the active metabolite AZT triphosphate. These results are of major significance both in enabling efficient treatment of the fetuses of HIV-infected women and in the prediction and understanding of the efficacy and toxicity of AZT in pregnant women and their fetuses.     

Evaluation of various methods of maternal placental blood collection for immunology studies

The collection of maternal placental intervillous blood (IVB), without contamination of fetal blood and with an accurate mononuclear cell profile, is essential for immunological studies of placental malaria and other infectious diseases of the placenta. We have compared five documented methods of IVB collection: perfusion, incision, biopsy, tissue grinding, and puncture (prick) for fetal blood contamination and mononuclear cell profiles using flow cytometry. Twenty-five placentas were obtained from Plasmodium falciparum and human immunodeficiency virus-negative primigravid and secundigravid women delivering at Nyanza Provincial Hospital in Kisumu, western Kenya. Each of the five methods was performed on the same placenta. Fetal red blood cell contamination was significantly lower for the prick and perfusion methods (4.1% and 8.3%, respectively) than for incision (59.5%), biopsy (42.6%), and tissue grinding (19.9%). Significant variation was noted among the five methods in the percentages of monocytes, total T cells, CD4+ and CD8+ T cells, B cells, and NK cells. Further, a pairwise comparison of prick and perfusion, the two methods with low fetal blood contamination, showed that they were not different for fetal red blood cell contamination levels; however, prick yielded significantly higher percentages of CD4 T cells and CD4 memory T cells than perfusion. Collection by prick was determined to be the best method of intervillous blood collection for immunology studies, and perfusion represented the next best method of choice due to high sample volume yield. Overall, in considering the advantages/disadvantages of the two methods with low fetal cell contamination, we conclude that a combination of prick and perfusion is most suitable for immunology studies.     

Passage of inert substances and oxygen in the human placenta

1. The vascular arrangement and the perfusion pattern of the human placenta is discussed from the point of view of the transfer of substances from the maternal blood through the placental membrane into the fetal blood. The functional unit of the human placenta is a stream of maternal blood in the intervillous space opposed to a large series of fetal capillaries (the multivillous stream bed system).2. The transfer of each inert substance in the human placenta is dependent upon the concentration difference of the substance in the maternal and fetal blood entering the placenta, the rates of blood flow and the permeability coefficient of the placental membrane. These relationships are graphically presented.3. The placental transfer of oxygen during maternal hypoxia in the human depends upon the difference in O₂ partial pressure in the entering blood streams, the rates of blood flow, the oxygen affinity and the capacity of maternal and fetal blood and the diffusion capacity of the placental membrane. These relationships are graphically presented.4. The transfer of oxygen under normal conditions in the human placenta depends upon the rates of blood flow and the diffusion capacity. These relationship are graphically presented for conditions of special composition of maternal and fetal blood entering the placenta.5. The transfer characteristics of the human placenta are compared with those in placentas with other vascular arrangements and perfusion patterns. The system of the human placenta is more efficient than a concurrent system and a pool system, but less efficient than a countercurrent system if the diffusion capacity of the placental membrane is high in relation to the fetal transport capacity. If the diffusion capacity is low in relation to the fetal transport capacity, all systems have about the same efficiency.With 4 Figures in the Text     

Acute funisitis of preterm but not term placentas is associated with severe fetal inflammatory response.

Acute funisitis, whose basic pathologic feature is umbilical vasculitis, constitutes a type of fetal inflammatory response to intrauterine infection. In the present study, a comparative analysis was performed between the clinicopathologic profiles of acute funisitis in term and preterm placentas along with measurement of fetal plasma interleukin 6 (IL-6) levels by specific immunoassay to assess the different biologic implications for the fetus. Acute funisitis in preterm placentas showed a significantly higher incidence of umbilical arteritis (P <.000001), higher fetal plasma IL-6 level (P <.0001), and higher prevalence of major perinatal morbidities (P <.0001). To assess the possible variation in fetal cell response to infectious agents according to gestational age, amnion cells and placental villous tissues obtained at different gestational ages were treated with bacterial lipopolysaccharides, and the IL-6 level of the culture media was assayed. Amnion cells and placental villous tissues from preterm placenta showed a more pronounced cytokine response than those from term placenta. The findings of this study indicate that the clinicopathologic significance of acute funisitis in term placentas is different from that of preterm placentas. Furthermore, they indicate that the robust inflammatory response of the fetus associated with elevated fetal plasma IL-6 level may reflect the biologic needs of the premature fetus to escape from the hostile intrauterine environment.     

Maternal Serum and Cord Blood Leptin Concentrations at Delivery in Normal Pregnancies and in Pregnancies Complicated by Intrauterine Growth Restriction

IntroductionLeptin is a polypeptide hormone, and in pregnancy, it is secreted by the placenta and maternal and fetal adipose tissues. Normal leptin production is a factor responsible for uncomplicated gestation, embryo development, and fetal growth. The study compared maternal serum and cord blood leptin concentrations at delivery in normal pregnancies and in pregnancies complicated by intrauterine growth restriction (IUGR).MethodsThe study was performed in 25 pregnant women with isolated IUGR and in 194 pregnant women without any complications. Leptin concentrations in maternal serum and in cord blood samples collected at delivery were measured by ELISA and subsequently analyzed by maternal body mass index (BMI), mode of delivery, and infant gender and birth weight. For comparative analyses of normally distributed variables, parametric tests were used, that is, the Student t test and a one-way ANOVA. The nonparametric Mann-Whitney test was used when the distribution was not normal. The Pearson correlation coefficient was calculated to assess the correlation between normally distributed variables (p < 0.05).ResultsIn pregnancies complicated by IUGR, the mean maternal serum leptin concentration at delivery was significantly higher (52.73 ± 30.49 ng/mL) than in normal pregnancies (37.17 ± 28.07 ng/mL) (p = 0.01). The mean cord blood leptin concentration in pregnancies complicated by IUGR was 7.97 ± 4.46 ng/mL and significantly lower than in normal pregnancies (14.78 ± 15.97 ng/mL) (p = 0.04). In normal pregnancies, but not in pregnancies complicated by IUGR, a statistically significant correlation was established between maternal serum leptin concentrations and maternal BMI at delivery (r = 0.22; p = 0.00). No statistically significant correlation was found between cord blood leptin concentrations and maternal BMI in either study subjects or controls. In normal pregnancies, but not in pregnancies complicated by IUGR, a strong correlation was observed between cord blood leptin concentrations and birth weight (r = 0.23; p = 0.00).ConclusionsElevated maternal blood leptin concentrations in pregnancies complicated by IUGR may indicate a significant adverse effect of elevated leptin on fetal growth. The differences in leptin concentrations, measured in maternal serum and in cord blood, between the study subjects and controls suggest that deregulated leptin levels may increase the risk of obstetric complications associated with placental insufficiency.     

Cell-free fetal DNA in the maternal circulation does not stem from the transplacental passage of fetal erythroblasts

Fetal cells, specifically fetal erythroblasts, as well as cell-free fetal DNA are present in the maternal circulation. Both are currently being investigated as a means for the non-invasive risk-free analysis of fetal genetic traits. The origin of this cell-free fetal DNA in the maternal circulation is currently unclear. Since numerous fetal erythroblasts have been demonstrated to exhibit an apoptotic phenotype in the form of fragmented nuclear DNA, it has been proposed that such trafficking fetal cells may be a possible source. This hypothesis is supported by reports of elevated numbers of fetal erythroblast and cell-free fetal DNA concentrations in pregnancies affected by pre-eclampsia or polyhydramnios. To address this question, we have examined fetal erythroblast numbers and cell-free DNA concentrations in the same maternal blood samples. Our study, performed on both normal and pathologically-affected pregnancies, indicates that no correlation exists between these two fetal cellular and molecular species. This is most evident in pregnancies affected by onset of preterm labour, where significant elevations in cell-free fetal DNA concentrations were detected without any concomitant elevation in fetal erythroblast numbers. Our data therefore suggest that an alternative cell type is the source of cell-free fetal DNA. Furthermore, it appears that the release of cell-free fetal DNA from this cell type is affected by pathological placental conditions which are not associated with an increase in fetal cell trafficking.     

Fetal endothelial cells express vascular cell adhesion molecule in the setting of chorioamnionitis

PROBLEM: In intrauterine infection, inflammatory mediators may be released into the fetal circulation prior to fetal infection. We hypothesize that, in chorioamnionitis, inflammation alters fetal blood vessels. To test this, fetal endothelial cells were examined for vascular cell adhesion molecule (VCAM). METHOD OF STUDY: Umbilical cords (n = 9) from placentas with chorioamnionitis were immunostained for VCAM. Controls from preterm preeclamptic pregnancies (n = 7) without histologic inflammation were selected, and matched for gestational age and method of delivery. VCAM sections were reviewed by a pathologist blinded to clinical diagnoses. RESULTS: All endothelial cells from each of the nine cords from placentas with chorioamnionitis had strong VCAM staining. Two of nine samples also had acute cord vasculitis. No cord endothelial cells from preeclamptic placentas demonstrated similar VCAM staining (p < 0.01). CONCLUSION: Histologic chorioamnionitis was associated with VCAM expression of the umbilical cord vessels. In chorioamnionitis, inflammatory mediators may have entered the fetal circulation to activate endothelial cells. Intrauterine inflammation was not restricted to the chorioamnion, but also involved the fetal circulation.