An in vitro model of human placental trophoblast deportation/shedding

Deportation of trophoblast shed from the placenta into the maternal circulation was first described over 100 years ago. Despite this, little is known about the quantity or nature of the shed and deported trophoblasts. Neither do we have a clear understanding of the fate of deported trophoblasts nor do we have a clear understanding of their effects on the maternal physiology. This deficiency is largely due to the inaccessibility of deported trophoblasts in vivo. This study aimed to produce a model that would allow us to study deported trophoblasts. We devised a system for culturing placental explants of 12-week gestation in cell culture inserts with a stainless steel mesh bottom that allowed the ready harvesting of shed/deported trophoblasts. Immunohistochemical and morphologic investigations demonstrated that these in vitro shed/deported trophoblasts are similar to those found in vivo and that apoptotic, necrotic and viable trophoblasts were shed from the explants. Inhibiting caspases induced a change from predominantly apoptotic to predominantly necrotic trophoblast shedding. We have devised an in vitro model that allows the collection of shed/deported trophoblasts which will significantly enhance our ability to study these cells. Our preliminary investigations confirm that apoptosis plays an important role in trophoblast shedding/deportation.     

Heparin prevents programmed cell death in human trophoblast

Heparin is used clinically for the prevention of pregnancy complications associated with prothrombotic disorders, especially antiphospholipid antibody syndrome. Recent studies have suggested that heparin may exert direct effects on placental trophoblast, independently of its anticoagulant activity. We now demonstrate that heparin abrogates apoptosis of primary first trimester villous trophoblast in response to treatment with the pro-inflammatory cytokines interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha. This multifunctional glycosaminoglycan also inhibited apoptosis induced by other agents, including staurosporin, broad-spectrum kinase inhibitor and thrombin. Furthermore, heparin attenuated caspase-3 activity, a hallmark of apoptosis, in human first trimester villous and extravillous trophoblast cell lines treated with peptidoglycan, a Toll-like receptor-2 agonist isolated from Staphylococcus aureus. The ability of heparin to antagonize cell death induced by such diverse apoptotic signals suggested that it acts as a survival factor for human trophoblast. We demonstrate that heparin, like epidermal growth factor (EGF) and heparin-binding EGF (HB-EGF), elicits phosphorylation of the EGF receptor and activation of the phosphatidyl inositol 3-kinase (PI3K)-, the extracellular signal-related kinase 1/2 (ERK1/2)- and the c-Jun NH2 terminal kinase (JNK)-signal transduction pathways in primary villous trophoblast. In summary, we have demonstrated that heparin activates multiple anti-apoptotic pathways in human trophoblast. Our results suggest that heparin may be useful in the management of at-risk patients, even in the absence of an identifiable thrombophilic disorder.     

X-linked inhibitor of apoptosis (XIAP) confers human trophoblast cell resistance to Fas-mediated apoptosis

Apoptosis occurs in the placenta throughout gestation, with a greater frequency near term in comparison to the first trimester. The Fas/FasL system represents one of the main apoptotic pathways controlling placental apoptosis. Although first trimester trophoblast cells express both Fas and FasL, they are resistant to Fas-induced apoptosis. Therefore, trophoblast resistance to Fas-mediated apoptosis may be due to the inhibition of the pathway downstream of Fas stimulation. Expression levels of X-linked inhibitor of apoptosis (XIAP) were recently shown to decrease in third trimester placentas, correlating with an increase in placental apoptosis. As a potent caspase inhibitor, XIAP prevents the activation of caspase-9 through its BIR3 domain and caspase-3 activation via the linker-BIR2 domain. In the present study, high levels of the active form of XIAP were detected in first trimester trophoblast cells, whereas term placental tissue samples predominantly expressed the inactive form of XIAP. Using a XIAP inhibitor, phenoxodiol, we demonstrate that XIAP inactivation sensitizes trophoblast cells to Fas stimulation, as evidenced by the anti-Fas mAb-induced decrease in trophoblast cell viability and increase in caspase-8, caspase-9 and caspase-3 activation. This suggests a functional role for XIAP in the regulation of the Fas apoptotic cascade in trophoblast cells during pregnancy.     

Effect of folic acid on homocysteine-induced trophoblast apoptosis

In trophoblast cells exposed to homocysteine (Hcy) we observed cellular apoptosis and the inhibition of trophoblast functions. Because folate and Hcy, linked in the same metabolic pathway, are inversely related, we investigated the role of folic acid in reversing the Hcy effect in human placenta. In primary trophoblast cells we examined the cytosolic release of cytochrome c, both M30 and terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling (TUNEL) and DNA laddering. Hcy (20 micromol/l) treatment resulted in cytochrome c release from mitochondria to the cytosol, and an increased number of M30-positive trophoblast cells and TUNEL positive nuclei. Furthermore, DNA cleavage in agarose gel and the determination of histone-associated DNA fragments have been investigated. Homocysteine induced DNA fragmentation and significantly reduced hCG secretion. The addition of folic acid (20 nmol/l) resulted in inhibition of the effects of Hcy on human trophoblast. These results suggest a protective role of folic acid in the prevention of trophoblast apoptosis linked to Hcy.     

Secretion of colony stimulating factor-1 by human first trimester placental and decidual cell populations and the effect of this cytokine on trophoblast thymidine uptake in vitro

The present in-vitro study using an enzyme-linked immunosorbentassay has identified the cell types responsible for colony stimulatingfactor-1 (CSF-1) production at the first trimester human placentaluterine interface. The major sources were observed to be decidualstromal cells and decidual CD56⁺ natural killer (NK) cells,but decidual CD3⁺ T cells did not produce CSF-1, reflectingfunctional differences between these two decidual lymphoid populations.Of a variety of cytokines tested, only interleukin-2 (IL-2)was found to augment CSF-1 secretion by decidual NK cells. Trophoblastcells also secreted CSF-1, but the amounts were small relativeto decidual stromal cells and NK cells. Therefore, most of theCSF-1 present at the implantation site appears to be maternallyderived. Co-culture of decidual NK cells on a monolayer of irradiatedtrophoblast did not augment CSF-1 secretion by decidual NK cells,indicating that the production of this cytokine is not stimulatedby contact with fetal trophoblast. CSF-1 was found to increase[³H]thymidine uptake by trophoblast cultured on laminin for72 h, but no such response was seen in trophoblast culturedon fibronectin, indicating that these extracellular matrix proteinshave differential effects on the response of trophoblast tothis cytokine.     

The isolation and characterization of a population of extravillous trophoblast progenitors from first trimester human placenta

BACKGROUND: It is widely accepted that most if not all villous cytotrophoblasts from term placentae are committed to differentiate into syncytiotrophoblast, but that early in gestation villous cytotrophoblasts are bipotential and capable of differentiating into either extravillous trophoblasts (EVTs) or syncytiotrophoblast. In contrast, our previous work has suggested that two separate populations of cytotrophoblast exist in the first trimester, one committed to EVT differentiation and the other to syncytiotrophoblast differentiation. In this work, we have isolated and characterized the population of 'EVT progenitors'. METHODS: First trimester villous explants were cultured for 10 days then subjected to sequential trypsinization. Viable cells that adhered to Matrigel following trypsinization were cultured for up to 5 days and characterized by immunohistochemistry. RESULTS: The isolation protocol yielded >90% cytokeratin positive trophoblasts, which expressed markers characteristic of EVT progenitors. Over 5 days of culture, these isolated putative EVT progenitors did not syncytialize, but approximately 20% differentiated into HLA-G positive EVTs. CONCLUSIONS: It is likely that the isolated putative EVT progenitors are the population of EVT progenitors previously identified in vivo. The characteristics of these isolated putative EVT progenitors provides further evidence for separate progenitors of EVT and syncytiotrophoblast in the first trimester.     

Nitric oxide inhibits polyamine-induced apoptosis in the human extravillous trophoblast cell line SGHPL-4

BACKGROUND: Polyamines are regulators of proliferation and differentiation in mammalian cells. They are also known to regulate cell survival and apoptosis, although their precise function varies between cell types. We have investigated the effect of polyamines on the apoptosis of human extravillous trophoblasts. METHODS: Using the extravillous trophoblast-derived cell line SGHPL-4 we performed time-lapse microscopy studies to evaluate the induction of apoptosis following exposure to polyamines. RESULTS: The polyamines spermine, and to a lesser extent spermidine, were able to induce apoptosis in extravillous trophoblasts. The induction of apoptosis occurred rapidly and was accompanied by DNA fragmentation and morphological changes consistent with the onset of apoptosis. Apoptosis was inhibited by the broad-spectrum caspase inhibitor Z-VAD-fmk, although no activity was detected using assays for caspase-2, -3, -6, -8 or -9 activity. We demonstrated that an oxidation product of spermine accounted for the induction of apoptosis and implicated the formation of hydrogen peroxide as this oxidation product. We have also demonstrated that exposure to nitric oxide inhibited the onset of spermine-induced apoptosis. CONCLUSIONS: Spermine and spermidine induce apoptosis in extravillous trophoblasts following their oxidation and the production of hydrogen peroxide. Nitric oxide is able to inhibit this apoptosis.     

Stromal cell-derived factor-1 (SDF-1/CXCL12) gene polymorphisms in pulmonary tuberculosis patients of south India

CXCL12 gene polymorphisms influence CXCL12 levels and may be associated with the outcome of host-pathogen interaction. Hence, the present study was carried out to find out whether CXCL12 gene polymorphisms are associated with susceptibility or resistance to pulmonary tuberculosis (PTB). Intron and 3' untranslated region (UTR) polymorphisms of CXCL12 gene were investigated among 184 patients with PTB and 187 healthy controls (HC) using polymerase chain reaction-based methods. The results revealed an increased frequency of G/A genotype of In2 +5887 [P = 0.034; odds ratio (OR) 1.66; 95% confidence intervals 1.04-2.66] and a decreased frequency of G/A genotype of 3'UTR +12197 polymorphisms (P = 0.051; OR 0.64; 95% CI 0.4-1.00) among patients than HCs. When the study subjects were categorized based on sex, significantly increased frequencies of G/A genotype (P = 0.013 P(c) = 0.039; OR 2.41) of In2 +5887 and G/G genotype (P = 0.005, P(c) = 0.015; OR 2.48) of 3'UTR +12197 polymorphisms were observed among female patients with PTB as compared to female HC. A significantly decreased frequency of the haplotype G-C-A-T (P = 0.006, P(c) = 0.030; OR 0.48) was noticed among female patients with PTB as compared to female HC. The study suggests that G/A genotype of In2 +5887 and G/G genotype of 3'UTR +12197 polymorphisms may be associated with susceptibility to PTB among females, and the haplotype G-C-A-T of CXCL12 gene may be associated with protection in females.     

Pregnancy: Differential increase in the maternal serum concentrations of the placental proteins human chorionic gonadotrophin, pregnancy-specific {beta}1-glycoprotein, human placental lactogen and pregnancy-associated plasma protein-A during the first half of normal pregnancy, elucidated by means of a mathematical model

The present study was performed to compare the increase in maternalserum concentrations of four placental proteins during the firsthalf of 240 normal pregnancies. The proteins were pregnancy-associatedplasma protein-A (PAPP-A), human chorionic gonadotrophin (HCG),human placental lactogen (HPL) hormone, and pregnancy-specific1-glyco-protein (PSG), all produced by trophoblast cells. Themedian increases were observed to be very close to exponentialgrowth curves. Based on simple assumptions, these growth curvescould be explained as being solely dependent on the growth ofthe placenta. The assumptions were that the proteins were producedin the placenta at a constant rate per gram of placental cellmass and secreted into the circulation shortly after synthesis.Our investigations showed that for two of the proteins, PSGand HPL, the rate constants were, in fact, close to the reportedgrowth rate of the placenta, whereas the PAPP-A production rateconstant was significantly higher than those of the others.The production curve for HCG was very different from that ofthe other proteins. PAPP-A and HCG must therefore have morecomplicated mechanisms for regulating the production. An equationwas constructed that permitted estimation of the molar productionof the placental proteins per gram of placental cell mass perday during the first half of normal pregnancy. The value washighest for HPL and lowest for PAPP-A.     

The effects of oxygen concentration and gestational age on extravillous trophoblast outgrowth in a human first trimester villous explant model

BACKGROUND: In the first trimester of human pregnancy, extravillous trophoblasts from placental villi invade the decidua temporarily occluding the spiral arteries, preventing maternal blood flow and creating a low-oxygen environment, which is believed to play an important role in the regulation of extravillous trophoblast outgrowth. This work aimed to quantify the effects of gestational age and oxygen concentration on extravillous trophoblast outgrowth. METHODS: A quantitative first trimester villous explant model was used to measure the frequency and area of extravillous trophoblast outgrowths from villi grown in 1.5 or 8% oxygen. RESULTS: The percentage of explants producing outgrowth declined independently of oxygen concentration as gestation increased from 8 to 12 weeks. Culture in 1.5% oxygen significantly reduced the frequency and area of outgrowths in comparison with 8% oxygen. HLA-G and alpha1 integrin were both expressed throughout outgrowths, with no difference in the expression between oxygen concentrations. Gestation influenced the response of explants to oxygen, with a significant differential response to oxygen concentration in placentae under 11 weeks of gestation, whereas in villi from placentae of 11 or 12 weeks, no differential response was observed. CONCLUSIONS: In the first trimester, oxygen and gestational age both regulate extravillous trophoblast outgrowth.     

Dimethylarginine dimethylaminohydrolase (DDAH) regulates trophoblast invasion and motility through effects on nitric oxide

BACKGROUND: Invasion of trophoblast into the uterine environment is crucial for establishing a successful pregnancy. Physiological production of nitric oxide (NO) by extravillous trophoblasts results in significant pro-invasive effects. NO synthesis is competitively inhibited by methylated arginine analogues such as asymmetric dimethylarginine (ADMA) but not the enantiomer symmetric dimethylarginine (SDMA). Within cells, the concentration of ADMA is regulated by the activity of the enzyme dimethylarginine dimethylaminohydrolase (DDAH). The aim of this study was to examine DDAH expression and function in trophoblasts. METHODS AND RESULTS: DDAH-1 and DDAH-2 messenger RNA and protein were demonstrated in first trimester placental tissue, primary extravillous trophoblasts and extravillous trophoblast-derived cell lines. DDAH activity was demonstrated in both cells and tissue. Overexpression of DDAH-1 in trophoblasts led to a number of significant changes, including an 8-fold increase in enzymatic activity, a 59% decrease in production of ADMA (but not SDMA), a 1.9-fold increase in NO and a 1.6-fold increase in cyclic guanosine monophosphate (cGMP) production. Functional assays showed that increased DDAH activity led to significantly increased cell motility and invasion in response to hepatocyte growth factor (HGF). CONCLUSIONS: DDAH may play an important role in the regulation of extravillous trophoblast function via its effects on ADMA and NO production.     

趋化因子基质细胞衍生因子1(SDF-1)及其受体CXCR4

趋化因子及其受体在免疫和炎症反应、造血以及HIV感染等方面发挥重要作用,其中基质细胞衍生因子-1SDF-1及其受体CXCR4由于在造血干细胞迁移、归巢以及HIV感染中的作用而受到关注,并对其作用机制进行了探讨,现就SDF-1及其受体CXCR4的有关内容作一综述。     

Human leucocyte antigen (HLA) expression of primary trophoblast cells and placental cell lines,determined using single antigen beads to characterize allotype specificities of anti-HLA antibodies

Human trophoblast cells express an unusual repertoire of human leucocyte antigen (HLA) molecules which has been difficult to define. Close homology between and extreme polymorphism at the classical HLA class-I (HLA-I) loci has made it difficult to generate locus-specific monoclonal antibodies (mAbs). The problem of defining an antibody''s reactivity against the thousands of existing HLA-I allotypes has often made it impossible to determine the HLA bound by a mAb in biological samples from a normal outbred population. Here we have used commercially available beads coated with individual HLA-I to characterize experimentally the reactivity of nine mAb against 96 common HLA-I allotypes. In conjunction with donor HLA-I genotyping, we could then define the specific HLA molecules bound by these antibodies in normal individuals. We used this approach to analyse the HLA expression of primary trophoblast cells from normal pregnancies; the choriocarcinoma cells JEG-3 and JAR; and the placental cell lines HTR-8/SVneo, Swan-71 and TEV-1. We confirm that primary villous trophoblast cells are HLA null whereas extravillous trophoblast cells express HLA-C, HLA-G and HLA-E, but not HLA-A, HLA-B or HLA-DR molecules in normal pregnancy. Tumour-derived JEG-3 and JAR cells reflect extravillous and villous trophoblast HLA phenotypes, respectively, but the HLA repertoire of the in vitro derived placental cell lines is not representative of either in vivo trophoblast phenotype. This study raises questions regarding the validity of using the placental cell lines that are currently available as model systems for immunological interactions between fetal trophoblast and maternal leucocytes bearing receptors for HLA molecules.     

Calcitonin gene-related peptide stimulates human villous trophoblast cell differentiation in vitro

Calcitonin gene-related peptide (CGRP) is a multifunctional peptide present in both maternal and fetal circulations in pregnancy. Its receptors have been identified on human trophoblast cells, but the role of CGRP in trophoblast differentiation remains unknown. This study was designed to determine the effect of CGRP on the differentiation of villous trophoblasts isolated from normal human term placentae. The morphological and functional differentiation of the trophoblast cells were assessed by desmosomal protein immunofluorescent staining and the quantification of hCG, estrogen and progesterone secretion. Results showed that (i) exposure of villous trophoblast cells to CGRP led to a dose-dependent increase in intracellular cyclic adenosine monophosphate (cAMP) accumulation; (ii) immunofluorescent staining with antidesmosomal antibody was identified at the boundaries between aggregated cytotrophoblast cells, and these stainings disappeared when cells fused to form syncytiotrophoblast cells; (iii) the formation of multinucleated syncytiums in primary cultured cytotrophoblasts was stimulated by CGRP as evidenced by the changes in antidesmosomal staining; (iv) CGRP increases trophoblast hCG secretion in a time- and dose-dependent manner, and this secretion was blocked by CGRP antagonist, CGRP(8-37), and (v) both 17beta-estradiol (E(2)) and progesterone concentrations in the culture medium were increased by CGRP, and these increases were dose dependent. These observations suggest that CGRP may be involved in the morphological and functional differentiation of trophoblast cells, and these actions might be attributed to CGRP-induced intracellular cAMP accumulation.     

Bax抑制因子1对人妊娠期肝内胆汁淤积症胎盘滋养细胞凋亡的影响及其机制

目的：探讨Bax 抑制因子1（BI-1）对人妊娠期肝内胆汁淤积症（ICP）胎盘滋养细胞凋亡的影响及其机 制。方法：选取2018 年5 月至2019 年5 月新疆维吾尔自治区人民医院产科住院分娩的ICP 孕产妇15 例为研究对 象,设为ICP 组,另取15 例正常孕产妇作为对照组,免疫组织化学显色检测ICP 组和对照组孕妇胎盘组织BI-1 的 表达;体外培养滋养细胞系HTR8,应用不同浓度（10、50、100 μmol/L）的牛磺胆酸（TCA）进行刺激,RTPCR 及免疫印迹检测HTR8细胞BI-1 mRNA 及蛋白的表达;用过表达BI-1 的慢病毒载体感染HTR8细胞,荧光显 微镜及RT-PCR 检测感染效率后,将细胞分为对照组（NC组）、TCA处理的感染LV-NC 细胞组（TCA+LV-NC 组）、 TCA处理感染LV-BI-1 细胞组（TCA+LV-BI-1 组）;分别用Annexin V-FITC、透射电镜及JC-1 流式线粒体膜电位 检测试剂盒检测3 组滋养细胞凋亡、线粒体超微结构及线粒体膜电位;免疫印迹检测3 组细胞Cyt-C 及凋亡相关 蛋白Bcl-2、Bax 及cleaved caspase-3 的表达。结果：与对照组相比,ICP 组胎盘组织BI-1 表达显著降低;体外实 验结果显示,TCA能够显著降低HTR8细胞BI-1 mRNA及蛋白表达,且呈浓度依赖性;应用慢病毒成功建立过 表达BI-1 的滋养细胞系。与NC组细胞相比,TCA+LV-NC 组与TCA+LV-BI-1 组细胞凋亡率和线粒体损伤水平均 显著增加,线粒体膜电位明显降低;而与TCA+LV-NC 组相比,LV+BI-1 组细胞凋亡率与线粒体损伤水平均明显 降低,线粒体膜电位显著增加;过表达BI-1 能够有效阻止TCA导致的滋养细胞Bcl-2/Bax 比值的降低,以及线粒 体Cyt-C 的释放及cleaved caspase-3 表达的增加。结论：BI-1 在ICP 患者胎盘组织中的表达显著降低,而体外过 表达BI-1 可能通过上调滋养细胞中Bcl-2/Bax 比值,抑制细胞线粒体膜电位降低及结构损伤,从而减少Cyt-C 的 释放,最终降低凋亡蛋白caspase-3 活化而改善TCA诱导的凋亡作用。     

Secretory characteristics and viability of human term placental tissue after overnight cold preservation

Collection of human term placentae for research purposes is generally limited during working hours. Preserving placental tissue overnight might help to postpone experiments and, by extent, to increase material availability. In this study, fragments from normal placentae were incubated at 37 degrees C either immediately after delivery or after preservation at 4 degrees C in a HEPES-buffered solution or in a Roswell Park Memorial Institute (RPMI) 1640 culture medium. Protein, human chorionic gonadotrophin (HCG), human placental lactogen (HPL) and lactate dehydrogenase (LDH) contents within preserved explants were similar to those within freshly delivered ones. In contrast, HCG and HPL amounts released during incubation of preserved tissue were lower than with freshly delivered tissue. Differences were significant only during the first 3 h of incubation. Hormone releases were similarly Ca(2+)-stimulated, and Co(2+)- and low temperature-inhibited in preserved and freshly delivered tissues. After preservation, LDH leakage was also reduced. Furthermore, before and after 37 degrees C incubation during 6 h, preserved tissue was morphologically indistinguishable from freshly delivered tissue and showed neither higher incidence of DNA fragmentation, nor elevated caspase-3 activity, both of which are markers of apoptosis. This study validates an original, useful and rapid method to preserve placental tissue. Consequently, this preservation model may facilitate the study of physiological processes regulating placental hormone secretion in normal and pathological conditions.     

Effects of anti-phospholipid antibodies on a human trophoblast cell line (HTR-8/SVneo)

Antibodies to phospholipids (aPL) have been shown to adversely affect trophoblast invasion in vivo and in vitro. HTR-8/SVneo cells derived from first trimester of pregnancy extravillous trophoblast were studied. Matrigel invasion assay, cytochemistry and cell-based enzyme-linked immunosorbant assay (ELISA) with aPL or normal IgG was used. Our data show that aPL at 100 microg/ml decrease invasiveness of HTR-8/SVneo cells to 60% of control (p<0.01), and this was also shown for primary cytotrophoblast (to 15.5% of control, p<0.001). aPL treatment caused a significant decrease in integrin alpha(1), alpha(5), and beta(1) proteins (86%, 84%, and 87%, respectively). We conclude that HTR-8/SVneo cell culture is a suitable model to study mechanisms of action of aPL on trophoblast, which in HTR-8/SVneo cells inhibit invasion by decreasing integrins alpha(5), alpha(1), and beta(1).