Third-trimester Placentas Research Articles

Pathologic findings of the placenta and clinical implications - recommendations for placental examination.

The placenta is a unique and complex organ that combines the circulatory systems of two or more individuals within a single dynamic organ with a set, short lifespan. A diverse spectrum of disorders, including infections as well as metabolic, genetic, circulatory, and maturation defects, may affect its function. Pathology investigation of the placenta is key for identifying several pathogenic processes in both the mother and the foetus. Aberrant placentation, maternal and foetal vascular compromise, infection, inflammatory immunologic conditions, and disorders of maturation are elements of newly proposed classification schemes. The clinical impact of placental examination consists of diagnosing maternal and foetal disease, identifying the potential for recurrence, correlating clinical pathological findings with distinct morphologic features, and identifying the aetiology responsible for growth restriction or foetal death. Gestational trophoblastic disease occurs more frequently in the first trimester; however, in very rare cases, it can affect the term or third-trimester placenta. The application of reproducible nomenclature is expected to facilitate progress in the diagnosis and treatment of obstetric and foetal disorders with placental manifestation. Therefore, this review aims to facilitate communication between obstetricians, neonatologists, and pathologists involved in this diagnostic process.

Low placenta at the mid trimester anomaly scan—A cause for concern?

AbstractObjectiveThis study was aimed to assess the predictive validity of internal os distance (IOD) in mid‐trimester scan for the prediction of third‐trimester low‐positioned placenta, and to define a cut‐off of IOD at which third‐trimester low‐positioned placenta could be identified, see the association of placental site (anterior/posterior), previous history of cesarean section with abnormal location of placenta in third trimester and see the maternal and neonatal outcomes.MethodsIt was a prospective cohort study of women with low‐positioned placenta (IOD < 20 mm) at mid‐trimester anomaly scan followed up in third trimester till birth. Relative risks for a low‐positioned placenta in the third‐trimester were calculated for women with posterior versus anterior, low‐lying placenta versus placenta previa and positive versus negative history of cesarean section. Multilevel likelihood ratios and corresponding ROC curves for different ranges of IOD were calculated.ResultsWomen with posterior placenta had a high risk of low positioned placenta compared to anterior placenta (9.28% vs. 0.74%); RR 1.45, similarly women with placenta previa had high risk compared to low lying placenta (68.57% vs. 1.69%); RR 6.51, so did the women with previous cesarean section (9.41% vs. 5.87%); RR 1.47.Conclusions93.42% placenta which were low positioned in mid trimester were normally situated in third trimester. The cut‐off for IOD in anterior placenta was −40 mm and in posterior placenta was 14.3 mm. IOD measurement and interpretation seems promising.

Early first-trimester transvaginal ultrasound screening for cesarean scar pregnancy in patients with previous cesarean delivery: analysis of the evidence

Obstetric hemorrhage is a leading cause of maternal morbidity and mortality. An important etiology of obstetric hemorrhage is placenta accreta spectrum. In the last two decades, there has been increased clinical experience of the devastating effect of undiagnosed, as well as late diagnosed, cases of Cesarean scar pregnancy. There is a growing body of evidence suggesting that Cesarean scar pregnancy is an early precursor of second- and third-trimester placenta accreta spectrum. As such, Cesarean scar pregnancy should be diagnosed in the early first trimester. This early diagnosis could be achieved by introducing regimented sonographic screening in pregnancies of patients with previous Cesarean delivery. This Opinion article evaluates the scientific and clinical basis of whether Cesarean scar pregnancy, with special focus on its early first-trimester discovery, complies with the accepted requirements of a screening test. Each of the 10 classical screening criteria of Wilson and Jungner were systematically applied to evaluate if the criteria were met by Cesarean scar pregnancy, to analyze if it is possible and realistic to carry out screening in a population-wide fashion.

Automated multivolume placental reconstruction using three-dimensional power Doppler ultrasound and infrared camera tracking.

Placental insufficiency contributes to many obstetric pathologies however there is no bedside clinical tool to evaluate placental perfusion. We have developed a method to acquire multiple three-dimensional power Doppler ultrasound (3D PD-US) volumes of placental vasculature with infrared camera tracking providing global coordinates. These are automatically reconstructed ('stitched') into a model of the entire placenta. The purpose of the study was to evaluate the accuracy of automated reconstruction in an US phantom and apply this technique to human placentas. A custom-designed acrylic phantom was constructed with dimensions mimicking a third-trimester placenta, containing 12 quadrilateral towers of varying heights submersed in tissue-mimicking solution. Triplicated three-dimensional ultrasound volumes of this phantom were acquired at three different acquisition angles using infrared camera tracking. Data was transformed into a three-dimensional cartesian volume and automatically stitched. A single-centre, cross-sectional feasibility study was conducted on uncomplicated second-to-third trimester singleton pregnancies using standardised obstetric settings. Multiple 3D PD-US and grayscale volumes of the placenta were acquired with infrared camera tracked coordinates. Volumes were stitched to create a model of placental vasculature. 6 phantom datasets were reconstructed at each of 3 volume angles with a median of 9 volumes required. Perfect volume alignment occurred in 66.7% of 648 datapoints. Mean distance error for volume misalignment was 2.92mm. Measurements of 210 distances in each stitched volume (2160 total distances) differed an average of 1.51mm from true measurements. These compare favourably with recent literature, though for a substantially larger phantom. 17 participants were scanned with 92% reconstruction success per placental volume set and 100% participant achievability. Median reconstruction time was 10 minutes. Placental vasculature was qualitatively assessed to be present, continuous, and detailed throughout. Volume measurement of entire segmented placentas was highly repeatable (ICC 0.96). We present an automated method to model the entire structure and vasculature of second-to-third trimester placentas, with verified accuracy and clinical feasibility for grayscale and power Doppler. This study builds the foundation to develop a practical screening tool for detecting placental insufficiency, and expansion to adult organ perfusion evaluation. This article is protected by copyright. All rights reserved.

TJP1 suppresses trophoblast cell invasion by expressing E2F8 in the human placenta

Adequate extravillous trophoblast (EVT) invasion into the maternal decidua is important for human placental development. We identified that E2F transcription factor 8 (E2F8) suppresses EVT invasion, and that tight junction protein-1 (TJP1) is a potential downstream target gene of E2F8. We investigated the role of TJP1 in the human placenta and regulation of TJP1 expression by E2F8. TJP1 expression decreased in E2F8 knockdown HTR-8/SVneo cells. TJP1 and E2F8 were co-expressed in villi in the first-trimester placenta and in EVTs and villi in the third-trimester placenta. TJP1 was significantly increased in the pre-eclamptic compared with control placenta. TJP1 knockdown increased the invasion of HTR-8/SVneo cells, while TJP1 overexpression inhibited cell invasion. Halo-E2F8 overexpression significantly increased TJP1 expression and TJP1 transcription compared with control placenta. Our findings suggest that E2F8 promotes TJP1 transcription, and that TJP1 expression by E2F8 inhibits EVT invasion. TJP1 and E2F8 may be related to pre-eclampsia pathogenesis.

Expression of PD-L1 in human placenta and retained product of conception of early pregnancy loss

Abstract Introduction/Objective Immune surveillance evasion and impeding rejection by the maternal immune response system are elemental in sustaining foetal development. The exact mechanism behind this paradoxical immune response remains unclear. Since the trophoblast directly interacts with the maternal immune-environment, these cells must have some contribution to local immunosuppression. The programmed death-1 receptor and its ligands (PD- 1/PDL1)illustrates a novel regulatory-costulatory pathway that plays a major role in establishing peripheral tolerance. It was recently proved that PDL1 is expressed at the feto-maternal interface is necessary for maintaining feto-maternal tolerance. We undertook this study to determine the expression-pattern of PD-L1 in formalin-fixed paraffin embedded tissues of human placentas in third trimester and retained product in early spontaneous abortions. Methods/Case Report Clinical history were recorded. The H&E sections of 40 placenta & 20 RPOC cases were examined. After evaluation appropriate sections were selected for IHC examination using anti-PD-L1 antibodies of Lab-vision and Biogenic Results (if a Case Study enter NA) Main focus of study was to see expression of PD-L1 at feto-maternal interface. 30 out of 40 third-trimester placenta expressed PD-L1 immunohistochemistry (13, 11 and 6 cases showed intense, fair and weak positivity respectively on outer surface of syncytiotrophoblast). 2 out of 20 early pregnancy loss cases in 11 & 9wk gestation expressed PD-L1 positivity. Conclusion Fetal cells in direct contact with maternal blood villous syncytiotrophoblast are major source of PD-L1 at the maternal-fetal interface and may utilize these immuno-suppressive mechanisms to ensure tolerance of conceptus. Failure to adapt this mechanism can lead to pregnancy loss.

Labour and premature delivery differentially affect the expression of the endocannabinoid system in the human placenta

Plasma concentrations of N-arachidonyletholamine (AEA), N-oleoylethanolamide (OEA) and N-palmitoylethanolamide (PEA) increase at term and can predict when a woman is likely to go into labour. We hypothesised that increased plasma AEA concentrations in women in preterm and term labour might also be increased and have a function in the placenta at the end of pregnancy. Here we examined the expression of the N-acylethanolamine-modulating enzymes fatty acid amide hydrolase (FAAH) and N-acyl-phosphatidylethanolamine-specific phospholipase-D (NAPE-PLD) and of the cannabinoid receptors (CB1 and CB2) in the placenta and their activation in an in vitro model of the third-trimester placenta to determine if those expressions change with labour and have functional significance. Expression of CB1, CB2, FAAH and NAPE-PLD was examined by immunohistochemistry (IHC) and RT-qPCR in placental samples obtained from four patient groups: preterm not in labour (PTNL), term not in labour (TNL), preterm in labour (PTL) and term in labour (TL). Additionally, the effects of AEA on a third-trimester human cell line (TCL-1) were evaluated. All ECS components were present in the third-trimester placenta, with NAPE-PLD and CB2 being the key modulated proteins in terms of expression. Functionally, AEA reduced TCL-1 cell numbers through the actions of the CB2 receptor whilst CB1 maintained placental integrity through the expression of the transcription regulators histone deacetylase 3, thyroid hormone receptor β 1 and the modulation of 5α reductase type 1. The placenta in the third trimester and at term is different from the placenta in the first trimester with respect to the expression of CB1, CB2, FAAH and NAPE-PLD, and the expression of these proteins is affected by labour. These data suggest that early perturbation of some ECS components in the placenta may cause AEA-induced PTL and thus PTB.

Bizarre Chorionic-type Trophoblast in Second-trimester and Third-trimester Placentas: Clinicopathologic Characterization of a Placental Pseudoneoplastic Lesion.

Bizarre (atypical/symplastic) cells have been described in various gynecologic normal tissues and benign neoplasms. This type of bizarre cytologic change is usually an incidental finding and is regarded as a benign process. We describe 17 cases of bizarre chorionic-type trophoblast in second-trimester and third-trimester placentas that created concern for an underlying/undersampled or incipient intraplacental trophoblastic neoplasm, predominantly found in intervillous trophoblastic islands (11/17), placental septae (6/17), chorionic plate (1/17), and/or the chorion layer of fetal membranes (2/17). The bizarre trophoblastic cells exhibited sheet-like or nested architecture, had a multifocal/patchy distribution, and/or were present as individual cells within hyaline stroma; they were characterized by large nuclei with smudgy chromatin and occasional intranuclear pseudoinclusions. The degree of atypia was classified as mild (0/17), moderate (3/17), or severe (14/17). Mitotic figures and necrosis were not identified. A dual immunohistochemical stain for trophoblast (hydroxyl-delta-5-steroid dehydrogenase) and a proliferation marker (Ki-67), performed in 15 cases, demonstrated 0% to very low proliferative activity within the bizarre trophoblast (0% to 2% [10/15], 3% to 8% [5/15]). Immunohistochemical stains for fumarate hydratase showed intact/retained expression in the bizarre cells in 7 of 7 cases. Clinical follow-up ranged from 1 to 45 months, and all patients were alive and well without subsequent evidence of a gestational trophoblastic or other neoplasms. We conclude that bizarre chorionic-type trophoblast in second-trimester or third-trimester placentas have the potential to mimic an intraplacental trophoblastic neoplasm but are likely a benign degenerative change. This study expands the spectrum of bizarre cells that occur in the gynecologic tract.

Differences in human placental mesenchymal stromal cells may impair vascular function in FGR.

Placentae from pregnancies with foetal growth restriction (FGR) exhibit poor oxygen and nutrient exchange, in part due to impaired placental vascular development. Placental mesenchymal stromal cells (pMSCs) reside in a perivascular niche, where they may influence blood vessel formation/function. However, the role of pMSCs in vascular dysfunction in FGR is unclear. To elucidate the mechanisms by which pMSCs may impact placental vascularisation we compared the transcriptomes of human pMSCs isolated from FGR (<5th centile) (n = 7) and gestation-matched control placentae (n = 9) using Affymetrix microarrays. At the transcriptome level, there were no statistically significant differences between normal and FGR pMSCs; however, several genes linked to vascular function exhibited notable fold changes, and thus the dataset was used as a hypothesis-generating tool for possible dysfunction in FGR. Genes/proteins of interest were followed up by real-time PCR, western blot and immunohistochemistry. Gene expression of ADAMTS1 and FBLN2 (fibulin-2) were significantly upregulated, whilst HAS2 (hyaluronan synthase-2) was significantly downregulated, in pMSCs from FGR placentae (n = 8) relative to controls (n = 7, P < 0.05 for all). At the protein level, significant differences in the level of fibulin-2 and hyaluronan synthase-2, but not ADAMTS1, were confirmed between pMSCs from FGR and control pregnancies by Western blot. All three proteins demonstrated perivascular expression in third-trimester placentae. Fibulin-2 maintains vessel elasticity, and its increased expression in FGR pMSCs could help explain the increased distensibility of FGR blood vessels. ADAMTS1 and hyaluronan synthase-2 regulate angiogenesis, and their differential expression by FGR pMSCs may contribute to the impaired angiogenesis in these placentae.

Pregnancy and Delivery Outcomes in Women With Persistent Versus Resolved Low-Lying Placenta in the Late Third Trimester.

The safest mode of delivery in low-lying placenta is debatable. Little is known about outcomes in low-lying placenta resolved during the late third trimester. We compare outcomes of women with persistent versus resolved low-lying placenta. A retrospective analysis on a prospective cohort of women with low-lying placenta confirmed at 28-30 weeks sonography (01/2009 to 03/2018). Women were followed up serially every 2 to 3 weeks until delivery to assess the placental edge-to-internal os distance (IOD), and included if scan was performed within 28 days before delivery. There were 86 women: in 21 the low-lying placenta resolved, whereas in 65 persisted (n=15 IOD 1-10 mm, n=50 IOD 11-20 mm). Antepartum bleeding associated with higher rates of urgent cesarean delivery in 1-10 mm (P=.041) but not in 11-20 mm (P=1.000) and >20 mm (P=.333). Among women with IOD >10 mm allowed to labor, vaginal delivery occurred in 76.7% (11-20 mm) and 94.1% (>20 mm) (P=.155), with no difference according to parity (70% and 80% in multiparas, P=.696; 60% and 72.7% in nulliparas, P=.698). Severe PPH (P=.922) and hemoglobin drop (P=.109) were similar among groups. Women with IOD 11-20 mm and >20 mm and vaginal delivery bled less than women with similarly located placenta and cesarean delivery (P=.009 and P=.048). Women with IOD >10 mm have high chances of deliver vaginally with no further increase of their hemorrhagic risk. Success of vaginal delivery is independent of parity and antepartum bleeding. Labor should be managed in an adequate hospital setting.

Variation of Diffusion Distance from Foetal to Maternal Circulation at Different Gestational Periods

Diffusion distance varies according to the gestational age of a mother. Moreover, this diffusion distance must be within a physiological range. Thus, the survivability of a growing foetus depends on this distance. For this study, 90 products of conception and placenta were collected and divided into three groups based on the trimester of pregnancy, and each group included 30 samples. Two tissue blocks were collected from each specimen after the sample was fixed with 10% formol saline for 48 hours. Afterwards, with further processing of the tissue, followed by H&amp;E staining, the diffusion distance was measured among the three groups by using crossed sealed ocular micrometre under the light microscope. The ANOVA test was considered for further statistical analysis. In the first trimester, the placenta diffusion distance from foetal to maternal circulation ranged from 53.20 – 68.30 (μm), and the mean ± SD was 60.46 ± 3.58 (μm). In the second-trimester placenta, the diffusion distance of placenta from foetal to maternal ranged from 23.20 – 45.30 (μm), and the mean ± SD was 36.05 ± 6.01 (μm). In the third-trimester placenta, diffusion distance from foetal to maternal ranged from 1.80 – 2.90 (μm) and the mean ± SD was 2.52 ± 0.22 (μm). Diffusion distance significantly reduced with the ageing of the placenta (p &lt; 0.00). With the help of this result, we can assume that the exchange of nutrients and gases proportionally increases with the advancement of pregnancy.

Glycan expression in chorionic villi from histocultures of women with early-onset preeclampsia: Immunomodulatory effects on peripheral natural killer cells

New evidence suggests that glycan expression in placental cells of women with invasive disorders of pregnancy differs from that in normal pregnant women. Hypothesizing that modifications of glycan expression could account for the course of preeclampsia, we established placental villous histocultures and compared glycan expression in women with preeclampsia with that in normal pregnant women and also in syncytialized BeWo cells, and we tested the effect of glycan expression on the functional phenotypes of circulating natural killer (NK) cells. Histocultures of third-trimester placentae from women with preeclampsia and full-term placentae from healthy pregnant women and BeWo choriocarcinoma cells were assessed for the expression of terminal glycans by lectin-binding assays. Circulating NK cells from nonpregnant healthy donors were tested in vitro for their cytotoxic activity and intracellular cytokine content. Histocultures from women with preeclampsia expressed significantly more mannose than did those from healthy pregnant women. Both histocultures and BeWo cells expressed terminal fucose, mannose, sialic acid, and N -acetylgalactosamine, although mean fluorescence intensity (MFI) expression was lower in choriocarcinoma cells than in cells from histocultures. Cocultures of circulating NK cells with K562 target cells resulted in a dose-dependent cytotoxicity effect, but the use of BeWo cells as target reduced cytotoxic activity; this reduction was not affected by syncytialization. Histocultures of placental villous tissue of women with preeclampsia expressed high levels of terminal mannose. We proposethat placental glycans may modulate the functional activity of circulating NK cells in the context of systemic inflammatory response in preeclampsia.

Third-trimester placentas of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive women: histomorphology, including viral immunohistochemistry and in-situ hybridization.

AimsThe wide variety of affected organ systems associated with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection highlights the need for tissue‐specific evaluation. We compared placentas from SARS‐CoV‐2‐positive and SARS‐CoV‐2‐negative women in our hospital in New York City, which became the epicenter of the coronavirus disease 2019 pandemic in March 2020. To date, some limited studies have been published on placentas from SARS‐CoV‐2‐positive women. The aim of our study, in addition to describing histomorphology, was to utilize in‐situ hybridization (ISH) for the S‐gene encoding the spike protein and immunohistochemistry (IHC) with the monoclonal SARS‐CoV‐2 spike antibody 1A9 for placental evaluation.Methods and resultsIn this study, 51 singleton, third‐trimester placentas from SARS‐CoV‐2‐positive women and 25 singleton, third‐trimester placentas from SARS‐CoV‐2‐negative women were examined histomorphologically according to the Amsterdam Criteria and with ISH and/or IHC. The corresponding clinical findings and neonatal outcomes also were recorded. Although no specific histomorphologic changes related to SARS‐CoV‐2 were noted in the placentas, evidence of maternal–fetal vascular malperfusion was identified, with placentas from SARS‐CoV‐2‐positive women being significantly more likely to show villous agglutination (P = 0.003) and subchorionic thrombi (P = 0.026) than placentas from SARS‐CoV‐2‐negative women. No evidence of direct viral involvement was identified with ISH and IHC.ConclusionsIn this study, third‐trimester placentas from SARS‐CoV‐2‐positive women were more likely to show evidence of maternal–fetal vascular malperfusion; however, ISH and IHC provided no evidence of direct viral involvement or vertical transmission.

Expression of angiogenic factor with G patch and FHA domains 1 (AGGF1) in placenta from patients with preeclampsia.

Preeclampsia (PE) is a major contributor to maternal and foetal morbidity and mortality worldwide. It manifests as high blood pressure and proteinuria in women at more than 20 weeks of gestation. Abnormal levels of anti- and pro-angiogenesis factors are known to be associated with PE. In the present study, we aimed to determine the localisation of angiogenic factor with G patch and FHA domains 1 (AGGF1) in the placenta and to compare the expression levels of AGGF1 in the third-trimester placentas of preeclamptic and normotensive pregnancies. Placental tissue samples were collected from women with PE (n = 28) and without PE (n = 28). The normotensive controls without PE were matched for gestational age at delivery with the patients with PE. The expression levels of AGGF1 in the placental tissues were evaluated using immunohistochemistry, quantitative reverse transcription polymerase chain reaction and Western blot. The immunoexpression of AGGF1 was localised in the syncytiotrophoblast tissue. Notable, the mRNA and protein expression levels of AGGF1 were decreased in preeclamptic placentas as compared with the normotensive control group (P < 0.05). Our results suggest that the decreased AGGF1 in preeclamptic placentas may be related to the pathogenesis of preeclampsia.

Maternal obesity influences expression and DNA methylation of the adiponectin and leptin systems in human third-trimester placenta

BackgroundIt is well established that obesity is associated with dysregulation of the ratio between the two major adipokines leptin and adiponectin. Furthermore, it was recently reported that maternal obesity has a significant impact on placental development. Leptin and adiponectin are present at the fetal-maternal interface and are involved in the development of a functional placenta. However, less is known about leptin and adiponectin’s involvement in the placental alterations described in obese women. Hence, the objective of the present study was to characterize the placental expression and DNA methylation of these two adipokine systems (ligands and receptors) in obese women.ResultsBiopsies were collected from the fetal and maternal sides of third-trimester placenta in obese and non-obese (control) women. In both groups, leptin levels were higher on the fetal side than the maternal side, suggesting that this cytokine has a pivotal role in fetal growth. Secondly, maternal obesity (in the absence of gestational diabetes) was associated with (i) elevated DNA methylation of the leptin promoter on fetal side only, (ii) hypomethylation of the adiponectin promoter on the maternal side only, (iii) significantly low levels of leptin receptor protein (albeit in the absence of differences in mRNA levels and promoter DNA methylation), (iv) significantly low levels of adiponectin receptor 1 mRNA expression on the maternal side only, and (v) elevated DNA methylation of the adiponectin receptor 2 promoter on the maternal side only.ConclusionOur present results showed that maternal obesity is associated with the downregulation of both leptin/adiponectin systems in term placenta, and thus a loss of the beneficial effects of these two adipokines on placental development. Maternal obesity was also associated with epigenetic changes in leptin and adiponectin systems; this highlighted the molecular mechanisms involved in the placenta’s adaptation to a harmful maternal environment.

Calreticulin Regulates Syncytialization Through Control of the Synthesis and Transportation of E-Cadherin in BeWo Cells.

During placental development, mononuclear cytotrophoblasts differentiate and fuse to syncytiotrophoblasts (STBs) to form syncytia, which secrete human chorionic gonadotropin (hCG). Decreased maternal perfusion of the placenta, which leads to placental dysfunction, induces changes in trophoblast syncytialization. Our previous study showed that calreticulin (CRT), a Ca2+-binding molecular chaperone found in the endoplasmic reticulum, is expressed in the human placenta and is involved in regulating extravillous trophoblast invasion, although its role in villous trophoblasts remains unclear. In this study, we investigated the functional role of CRT in trophoblast differentiation using the human trophoblast-like cell line BeWo, in which CRT gene expression was knocked down. We found that CRT was highly expressed in human third-trimester placentas and mainly localized in STBs. The fetal growth restriction group exhibited significantly lower CRT expression levels than did the control group. In BeWo cells, CRT knockdown markedly suppressed forskolin-induced cell fusion and β-hCG secretion. As for the mechanism responsible for these effects, the cell surface expression of E-cadherin, a key adhesion molecule related to syncytialization, was decreased, and E-cadherin accumulated adjacent to the Golgi apparatus in the CRT-knockdown cells, which led to dysfunctional cell-to-cell adhesion. Additionally, metabolic labeling and a pulse-chase study revealed that the protein expression of E-cadherin was suppressed at the translational level in the CRT-knockdown cells. Collectively, these results demonstrate that CRT regulates syncytialization by ensuring appropriate control of both the synthesis and transportation of E-cadherin, suggesting that CRT expression is important for placental development during pregnancy.

Equilibrative Nucleoside Transporter 1 (ENT1, SLC29A1) Facilitates Transfer of the Antiretroviral Drug Abacavir across the Placenta.

Abacavir is a preferred antiretroviral drug for preventing mother-to-child human immunodeficiency virus transmission; however, mechanisms of its placental transfer have not been satisfactorily described to date. Because abacavir is a nucleoside-derived drug, we hypothesized that the nucleoside transporters, equilibrative nucleoside transporters (ENTs, SLC29A) and/or Na+-dependent concentrative nucleoside transporters (CNTs, SLC28A), may play a role in its passage across the placenta. To test this hypothesis, we performed uptake experiments using the choriocarcinoma-derived BeWo cell line, human fresh villous fragments, and microvillous plasma membrane (MVM) vesicles. Using endogenous substrates of nucleoside transporters, [3H]-adenosine (ENTs, CNT2, and CNT3) and [3H]-thymidine (ENTs, CNT1, and CNT3), we showed significant activity of ENT1 and CNT2 in BeWo cells, whereas experiments in the villous fragments and MVM vesicles, representing a model of the apical membrane of a syncytiotrophoblast, revealed only ENT1 activity. When testing [3H]-abacavir uptakes, we showed that of the nucleoside transporters, ENT1 plays the dominant role in abacavir uptake into placental tissues, whereas contribution of Na+-dependent transport, most likely mediated by CNTs, was observed only in BeWo cells. Subsequent experiments with dually perfused rat term placentas showed that Ent1 contributes significantly to overall [3H]-abacavir placental transport. Finally, we quantified the expression of SLC29A in first- and third-trimester placentas, revealing that SLC29A1 is the dominant isoform. Neither SLC29A1 nor SLC29A2 expression changed over the course of placental development, but there was considerable interindividual variability in their expression. Therefore, drug-drug interactions and the effect of interindividual variability in placental ENT1 expression on abacavir disposition into fetal circulation should be further investigated to guarantee safe and effective abacavir-based combination therapies in pregnancy.

Enhanced expression of IFI16 and RIG-I in human third-trimester placentas following HSV-1 infection.

The innate immune response in the placenta depends on the ability of maternal immune cells and fetal trophoblast cells to detect and eliminate invading pathogens through germline-encoded pattern recognition receptors (PRRs). In the present study, we analysed the transcripts and protein expression of interferon (IFN)-inducible protein (IFI)16, melanoma differentiation-associated protein 5 (MDA5), RIG-I-like receptor (RIG-I) and Toll-like receptor (TLR)-3 in third-trimester human placentas and investigated cytokine profiles generated during herpes simplex type 1 (HSV-1) infection. Decidual and chorionic villous biopsies (38-42 weeks of gestation) were obtained from healthy women immediately after a caesarean section. The expression of the DDX58 (RIG-I), IFIH1 (MDA5), IFI16 and TLR3 transcripts was measured using quantitative real-time polymerase chain reaction (qRT-PCR). Extracellular cytokine and PRRs levels were then quantified by enzyme-linked immunosorbent assays (ELISAs). All examined PRRs genes, including DDX58, IFIH1, IFI16 and TLR3, were expressed constitutively at the mRNA and protein levels in the placental biopsies. The concentration of the IFI16 protein was increased in HSV-1-infected decidual and chorionic villous explants compared to those of mock-infected tissues (P=0·029). Higher protein expression levels of RIG-I in both the maternal and fetal parts of the placenta were found (P=0·009 and P=0·004, respectively). In addition, increased production of IFN-β by HSV-1-infected tissues was noticed (P=0·004 for decidua, P=0·032 for chorionic villi). No significant differences in the IFN-α, interleukin (IL)-6 and IL-8 levels were found. These results showed that HSV-1 infection can enhance the expression of IFI16 and RIG-I proteins in the human term placenta.

Expression of retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) in third-trimester placentas following cytomegalovirus infection ex vivo

Expression of retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) in third-trimester placentas following cytomegalovirus infection ex vivo

Up-regulation of CD81 inhibits cytotrophoblast invasion and mediates maternal endothelial cell dysfunction in preeclampsia

Preeclampsia (PE) is initiated by abnormal placentation in the early stages of pregnancy, followed by systemic activation of endothelial cells of the maternal small arterioles in the late second or third trimester (TM) of pregnancy. During normal pregnancy, placental cytotrophoblasts (CTBs) invade the maternal uterine wall and spiral arteries, whereas this process is interrupted in PE. However, it is not known how the malformed placenta triggers maternal endothelial crisis and the associated manifestations. Here, we have focused on the association of CD81 with PE. CD81, a member of the tetraspanin superfamily, plays significant roles in cell growth, adhesion, and motility. The function of CD81 in human placentation and its association with pregnancy complications are currently unknown. In the present study, we have demonstrated that CD81 was preferentially expressed in normal first TM placentas and progressively down-regulated with gestation advance. In patients with early-onset severe PE (sPE), CD81 expression was significantly up-regulated in syncytiotrophoblasts (STBs), CTBs and the cells in the villous core. In addition, high levels of CD81 were observed in the maternal sera of patients with sPE. Overexpressing CD81 in CTBs significantly decreased CTB invasion, and culturing primary human umbilical vein endothelial cells (HUVECs) in the presence of a high dose of exogenous CD81 resulted in interrupted angiogenesis and endothelial cell activation in vitro. Importantly, the phenotype of human PE was mimicked in the CD81-induced rat model.