Genetic origin and proportion of basal plate surface-lining cells in normal and abnormal pregnancies

The human placenta is a transient organ, the villous surface of which is in direct contact with the maternal circulation during pregnancy. Thus, the syncytiotrophoblast and the basal plate-lining cells are considered continuous with the endothelial layer of the maternal vasculature. Two types of cells are found on the surface of the basal plate: trophoblasts (of fetal origin) and endothelial cells of putative maternal origin. Histologic abnormalities have been described in the basal plate of the placenta obtained from patients with preeclampsia and intrauterine growth restriction. Moreover, endothelial cell dysfunction and intravascular inflammation are key features of preeclampsia. The objectives of this study were to: (1) determine the origin of the endothelial cells located in the basal plate surface of the placenta (from male fetuses); and (2) analyze the relative proportion of the intervillous surface of the basal plate occupied by trophoblasts and endothelial cells. Immunohistochemistry and morphometry were performed in placentas from women in the following clinical groups: (1) normal-term pregnancies (n = 15); (2) severe preeclampsia at term (n = 15); (3) small-for-gestational-age (SGA) neonates delivered at term (n = 15); (4) preterm deliveries (<37 weeks) without inflammation (n = 5); and (5) preterm preeclampsia (n = 5). Laser capture microdissection and polymerase chain reaction were used to determine the allelic pattern of the amelogenin gene of the endothelial cells on the intervillous surface of the basal plate. Our results showed that: (1) the endothelial cells lining the basal plate in placentas of male fetuses were uniformly of maternal origin; and (2) in placentas from uncomplicated pregnancies, the median proportion of trophoblasts and endothelial cells covering the surface of the basal plate were 27.7% and 46.5%, respectively. The remaining area of the intervillous surface of the basal plate was composed of fibrin and anchoring villi. Of interest, placentas from women who delivered an SGA neonate had a higher proportion of trophoblasts and a lower proportion of endothelial cells lining the basal plate than those from normal pregnancies (P < .05). The same tendency was observed in placentas from patients with preeclampsia. This study demonstrates that endothelial cells of maternal origin cover the intervillous surface of the basal plate of the placenta, along with trophoblasts of fetal origin. The proportion of this surface lined by trophoblasts is greater in placentas from SGA and preeclampsia than in normal pregnancy. We propose that this change reflects a compensatory mechanism whereby the basal plate surface covered by injured endothelial cells is replaced by trophoblasts or results from a failure of trophoblastic involution in abnormal pregnancies. Our observations also suggest that the lining of the basal plate can provide information about the pathology of endothelial cells in complications of pregnancy.     

妊娠期高血压疾病胎盘组织中CASR和EGFR的相关研究

目的探讨在妊娠期高血压疾病患者胎盘组织中细胞外钙受体（CASR）和表皮生长因子受体（EGFR）的表达情况及其相互关系。方法通过免疫组织化学方法检测妊娠期高血压疾病患者64例（妊娠期高血压组21例,子痫前期轻度组23例,重度组20例）及健康足月孕妇20例（对照组）胎盘组织中CASR和EGFR蛋白的表达情况。结果 （1）妊娠期高血压疾病患者胎盘组织中CASR在妊娠期高血压组表达水平为59.0532±8.039,子痫前期轻度组患者中为64.3623±3.7278,两组比较,差异有统计学意义（P〈0.0001）;CASR在子痫前期重度组患者中表达为112.2831±6.2060,与妊娠期高血压组比较,差异有统计学意义（P〈0.0001）,与子痫前期轻度组比较,差异有统计学意义（P〈0.0001）。CASR的蛋白在妊娠期高血压组患者胎盘组织中表达水平为59.0532±8.039,对照组为54.8585±4.3035,两组比较,差异无显著性（t=0.08,P=0.7759）。（2）妊娠期高血压疾病患者胎盘组织中表皮生长因子受体（EGFR）在妊娠期高血压组表达水平为56.174±3.1020,子痫前期轻度组患者中为78.6844±2.6713,两组比较,差异有统计学意义（t=18.73,P=0.0001）;EGFR在子痫前期重度组患者中表达为94.2090±6.8352,与子痫前期轻度组比较,差异有统计学意义（t=11.37,P〈0.0001）。（3）胎盘组织中CASR和表皮生长因子受体（EGFR）表达量呈正相关关系（r=0.352,P〈0.05）。结论妊娠期高血压疾病患者胎盘组织中CASR的蛋白表达升高和EGFR激活及过度增高,可能在妊娠期高血压疾病发生发展中起重要作用。     

Preeclampsia, a pregnancy-specific disease, is associated with fetal monocyte activation

The maternal syndrome of preeclampsia is an exclusively pregnancy-related illness involving multiple organs and severe forms may be complicated by HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome. Recently, it has been proposed that both normal pregnancy and preeclampsia are associated with a systemic activation of the nonspecific maternal immune system and that, in particular, monocytes have a central role in the adjustment of maternal immune functions in pregnancy. Here we have investigated the role of the fetal nonadaptive immune system in normal term delivery, uncontrollable preterm labor, and preeclampsia. We demonstrate that spontaneous delivery at term as well as preterm occurrence of preeclampsia or HELLP syndrome are accompanied by an increased intracellular production of IL-6 in fetal monocytes, indicating strong activation of this cell type. In contrast, we show that elective cesarean delivery at term in the absence of labor or preterm delivery due to uncontrollable labor are not accompanied by an increased production of IL-6 in these cells. These results suggest that increased IL-6 synthesis in fetal monocytes may be a process occurring in association with normal spontaneous term delivery and that this process obviously occurs in early pregnancy in case of preeclampsia. Therefore, we propose that the activation of fetal monocytes as effectors of the innate immunity may be involved in mechanisms inducing spontaneous term delivery and that the occurrence of preeclampsia may be based on dysfunctions of probably both the maternal and the fetal innate immune system.     

The genetics of pre‐eclampsia: a feto‐placental or maternal problem?

Pre-eclampsia is a potentially life-threatening disease of women during pregnancy leading to hypertension and proteinuria. It affects 1 in 15 pregnancies but, despite intense research efforts, the cause of the disease remains mysterious. Because pre-eclampsia only occurs during pregnancy and its symptoms resolve after delivery, factors from the placenta are thought to be involved. The role of the placenta could be production of 'abnormal' factors that initiate widespread inflammation and vaso-constriction. Alternatively, because the placenta normally contributes to maternal cardiovascular adaptations of pregnancy, it may be that normal placental functions fail in pre-eclampsia or that susceptibilities in the mother to hypertensive, vascular and/or renal disease prevent the appropriate normal responses to them. The potential contributions of both maternal and fetal genes to the onset of the disease have complicated the genetic analysis of the disease in humans. Recent studies have identified strains of transgenic and mutant mice that develop the hallmark features of pre-eclampsia-like disease - gestational hypertension, proteinuria and kidney lesions (glomerulosclerosis). Comparison of three different mouse models suggests that pre-eclampsia can be initiated by at least three independent mechanisms: pre-existing borderline maternal hypertension that is exacerbated by pregnancy (BPH/5 strain of mice), elevated levels of the vasoconstrictor angiotensin II in the maternal circulation by placental over-production of renin (renin/angiotensinogen transgenic mice), and placental pathology (p57Kip2 mutant mice). These findings imply that the pathogenesis of pre-eclampsia cannot be explained by a single mechanism. Therefore, segregation of the human disease into different subtypes may be a key first step in identifying genetic risk factors.     

XIAP Bax mRNA在妊娠期高血压疾病胎盘中的表达及其意义

目的探讨凋亡相关基因XIAP Bax mRNA在妊娠期高血压疾病胎盘中的表达及其意义.方法采用RT-PCR方法研究45例妊娠期高血压疾病病例和15例正常妊娠病例胎盘组织中XIAP Bax mRNA的表达.结果 (1)子痫前期患者XIAP mRNA的表达显著降低(P＜0.01),而妊娠期高血压组XIAP mRNA与正常妊娠组相比表达无显著变化(P＞0.05).(2)Bax mRNA在子痫前期患者中表达显著升高(P＜0.01),而在妊娠期高血压组和正常妊娠组之间表达无显著变化(P＞0.05).(3)XIAP和Bax表达含量间呈负相关.结论 XIAP Bax在妊娠期高血压疾病的发病中起着重要作用,妊娠期高血压疾病的发病可能与XIAP表达的降低和Bax表达的增加有关.XIAP可能通过调节Bax的表达发挥作用.     

Review of the immune mechanisms of preeclampsia and the potential of immune modulating therapy

Successful pregnancy relies on maternal immunologic tolerance mechanisms limit maladaptive immune responses against the semi-allogeneic fetus and placenta and support fetal growth. Preeclampsia is a common disorder of pregnancy that affects 4–10% of pregnancies and is a leading cause of maternal and neonatal morbidity and mortality. Preeclampsia clinically manifests as maternal hypertension, proteinuria, and progressive multi-organ injury likely triggered by hypoxic injury to the placenta, resulting in local and systemic anti-angiogenic and inflammatory factor production. Despite the steady rising rates of preeclampsia in the United States, effective treatment options are limited to delivery, which improves maternal status often at the cost of prematurity in the newborn. Preeclampsia also increases the lifelong risk of cardiovascular disease for both mother and infant. Thus, identifying new therapeutic targets is a high priority area to improve maternal, fetal, and infant health outcomes. Immune abnormalities in the placenta and in the maternal circulation have been reported to precede the clinical onset of disease. In particular, excessive systemic and placental complement activation and impaired adaptive T cell tolerance with Th1/Th2/Th17/Treg imbalance has been reported in humans and in animal models of preeclampsia. In this review, we focus on the evidence for the immune origins of preeclampsia, discuss the promise of immune modulating therapy for prevention or treatment, and highlight key areas for future research.     

胎盘发育和子痫前期

胎盘是妊娠期间胎儿和母体之间的桥梁,具有血流灌注、物质交换、免疫耐受和妊娠适应性调节等功能,对保障胎儿发育和母体健康发挥关键作用。胎盘发育不良与子痫前期等妊娠疾病密切相关。在本文中,我们总结了人类滋养层细胞分化和胎盘功能单元构建的最新研究进展,并讨论了可能导致子痫前期发病的因素。     

Human physiological adaptation to pregnancy: Inter‐ and intraspecific perspectives

Reproductive success requires successful maternal physiological adaptation to pregnancy. An interspecific perspective reveals that the human species has modified features of our haplorhine heritage affecting the uteroplacental circulation. We speculate that such modifications — including early implantation and deep, widespread invasion of fetal (trophoblast cells) into and resultant remodeling of maternal uterine vessels — are responses to or compensation for the biomechanical constraints imposed by bipedalism which, in turn, render our species susceptible to the pregnancy complication of preeclampsia. Preeclampsia is characterized by incomplete remodeling of maternal uterine vessels as the result of shallow trophoblast invasion, which in turn reduces uteroplacental blood flow and frequently leads to intrauterine growth restriction (IUGR). Using an intraspecific perspective, we consider the fitness‐related consequences of variation in uteroplacental blood flow during high‐altitude pregnancy. Although birth weights are reduced at high altitudes in Bolivia, multigenerational Andean residents are relatively protected from altitude‐associated IUGR. Our preliminary data suggest that Andean women have greater uteroplacental oxygen delivery than European high‐altitude residents due to more complete growth and remodeling of maternal uterine vessels. Identification of the physiological and genetic mechanisms involved in such inter‐ and intraspecific variations in pregnancy physiology will likely be useful for understanding human evolution and contemporary challenges to successful reproduction. Am. J. Hum. Biol. 15:330–341, 2003. © 2003 Wiley‐Liss, Inc.     

Angiotensin II regulation of ovine fetoplacental artery endothelial functions: interactions with nitric oxide

During normal pregnancy, elevated angiotensin II (Ang II) concentrations in the maternal and fetal circulations are associated with dramatic increases in placental angiogenesis and blood flow. Much is known about a local renin–angiotensin system within the uteroplacental vasculature. However, the roles of Ang II in regulating fetoplacental vascular functions are less well defined. In the fetal placenta, the overall in vivo vasoconstrictor responses of the blood vessels to Ang II infusion is thought to be less than that in its maternal counterpart, even though infused Ang II induces vasoconstriction. Recent data from our laboratories suggest that Ang II stimulates cell proliferation and increases endothelial nitric oxide synthase (eNOS) and production of nitric oxide (NO) in ovine fetoplacental artery endothelial cells. These data imply that elevations of the known vasoconstrictor Ang II in the fetal circulation may indeed play a role in the marked increases in fetoplacental angiogenesis and that Ang II-elevated endothelial NO production may partly attenuate Ang II-induced vasoconstriction on vascular smooth muscle. Together with both of these processes, the high levels of Ang II in the fetal circulation may serve to modulate overall fetoplacental vascular resistance. In this article, we review currently available data on the expression of Ang II receptors in the ovine fetal placenta with particular emphasis on the effects of Ang II on ovine fetoplacental endothelium. The potential cellular mechanisms underlying the regulation of Ang II on endothelial growth and vasodilator production are discussed.     

TFPI-2在妊娠期子痫前期患者血浆及胎盘中的表达

目的：妊娠期高血压疾病患者血液呈异常高凝状态,母体脏器和胎盘组织中可见大量血栓形成,本实验的目的是探讨外源性凝血途径抑制物——组织因子途径抑制物2(tissue factor pathway inhibitor 2, TFPI-2)在妊娠期高血压疾病患者血浆及胎盘组织中的变化及临床意义。方法：采用酶联免疫吸附试验(ELISA)检测妊娠期高血压患者、子痫前期患者及正常妊娠孕妇血浆中TFPI-2的水平并同时采用免疫组织化学法测定胎盘组织中TFPI-2的表达情况。结果：与正常妊娠组相比,妊娠期高血压组血浆及胎盘组织中TFPI-2表达无显著性差异(P>0.05);子痫前期组血浆及胎盘组织中TFPI-2表达明显降低,与正常妊娠组和妊娠期高血压组相比,差异均有显著性(P<0.05)。结论：TFPI-2可能在子痫前期的发生、发展中起着重要的作用。     

The role of intraplacental vascular smooth muscle in the dynamic placenta: a conceptual framework for understanding uteroplacental disease

Although non-innervated, the placenta must continually accommodate changes in uteroplacental pressure (due to spiral artery failure, maternal position, maternal emotional state, etc.), which might otherwise be expected to result in rapid feto-maternal water fluxes in the highly water-permeable human hemochorial placenta. Uteroplacental flow must also be under the same influences, producing temporary, or permanent, regions of poor intervillous flow, yet the reduction of umbilical vein oxygen content that would be expected to be produced by such shunts of feto-placental blood do not occur in the normal fetus. We suggest that there is a local villus tree mechanism matching intravillus flow of fetal blood to local uteroplacental oxygen content. By analogy to ventilation/perfusion (V/Q) matching in the postnatal lung we suggest the term U/Q matching for this mechanism in the placenta. We further suggest that such disturbances in flow matching are compensated for by the fetus, via complementary adjustment of umbilico-chorionic artery and umbilical venous flow resistances, utilizing the differing sensitivities of vascular smooth muscle tissues of embryonic and extra-embryonic origin to vasoactive agents.     

妊娠期高血压疾病孕妇外周血中游离胎儿DNA的检测

目的探讨实时荧光定量PCR（RQ—PCR）检测孕妇外周血中胎儿游离DNA对预测及预防妊娠期高血压疾病的应用价值。方法选15例子痫前期孕妇及正常孕妇20例，用RQ—PCR法检测各例血浆中GAPDH及SRY水平，通过2^-△△ct法分析两组孕妇间的差异。结果22例孕男胎检出SRY21例，13例孕女胎均未检出，子痫前期组胎儿DNA水平明显高于正常组（P=0．009），两者比值为3．57。结论RQ—PCR法检测孕妇外周血中胎儿DNA可作为预测及预防妊高征的一种有效手段。     

MMP-9和IL-12在妊娠期高血压疾病胎盘上的表达

目的通过分析子痫前期患者与正常晚孕妇女胎盘组织中基质金属蛋白酶一9和白介素12的表达,探讨其在妊娠期高血压疾病(PIN)中的作用及两者的相关性。方法采用免疫组织化学染色法测定MMP-9和IL-12在28例妊娠期高血压疾病患者(10例为子痫前期轻度;18例为子痫前期重度)和10例正常妊娠患者胎盘上的表达。结果妊娠期高血压疾病组胎盘MMP-9的表达明显低于正常妊娠组(P<0.01);妊娠高血压疾病组胎盘IL-12的表达明显高于正常妊娠组(P>0.01),随病情加重MMP-9的表达有下降趋势;IL-12的表达有升高趋势,有统计学意义。结论与正常妊娠相比妊娠期高血压疾病组胎盘IL-12表达明显增加,MMP-9表达明显下降,且两因子表达与病情正相关。表明两因子参与了妊娠期高血压疾病的发生与发展。     

Sera from preeclampsia patients elicit symptoms of human disease in mice and provide a basis for an in vitro predictive assay

Early diagnosis and treatment of preeclampsia would significantly reduce maternal and fetal morbidity and mortality. However, its etiology and prediction have remained elusive. Based on the hypothesis that sera from patients with preeclampsia could function as a "blueprint" of causative factors, we describe a serum-based pregnancy-specific mouse model that closely mirrors the human condition as well as an in vitro predictive assay. We show that a single administration of human preeclampsia serum in pregnant IL-10-/- mice induced the full spectrum of preeclampsia-like symptoms, caused hypoxic injury in uteroplacental tissues, and elevated soluble fms-like tyrosine kinase 1 and soluble endoglin, markers thought to be related to the disease. The same serum sample(s) induced a partial preeclampsia phenotype in wild-type mice. Importantly, preeclampsia serum disrupted cross talk between trophoblasts and endothelial cells in an in vitro model of endovascular activity. Disruption of endovascular activity could be documented in serum samples as early as 12 to 14 weeks of gestation from patients who subsequently developed preeclampsia. These results indicate that preeclampsia patient sera can be used to understand the pregnancy-specific disease pathology in mice and can predict the disorder.     

Preeclampsia-related inflammatory cytokines regulate interleukin-6 expression in human decidual cells

Preeclampsia, a common pregnancy disorder associated with an increase in systemic inflammation, is the leading cause of maternal and fetal morbidity and mortality throughout the world. It is associated with shallow extravillous trophoblast invasion of the decidua, leading to uteroplacental blood flow that is inadequate for the developing fetal-placental unit. In preeclamptic women, interleukin-6 (IL-6) levels in plasma, but not placenta, are elevated, prompting evaluation of the decidua as a potential source of this excess, circulating IL-6. The current study found significantly higher immunohistochemical staining for IL-6 in decidual cells from preeclamptic versus preterm, gestational age-matched control placentas. Pro-inflammatory cytokines associated with the genesis of preeclampsia (i.e., tumor necrosis factor-alpha and interleukin-1beta) enhanced IL-6 mRNA levels and increased secreted IL-6 levels in first trimester leukocyte-free decidual cell incubations, as measured by real time quantitative RT-PCR, ELISA, and Western blotting. Therefore, decidual cell-derived IL-6 may contribute to excess circulating IL-6 levels that can promote both endothelial cell dysfunction (and subsequent vascular dysfunction) and the pathogenesis of preeclampsia whereas locally elevated IL-6 levels may contribute to an excess of decidual macrophages implicated in shallow extravillous trophoblast invasion of the decidua.     

Placental adaptive responses and fetal programming

Fetal programming occurs when the normal pattern of fetal development is disrupted by an abnormal stimulus or 'insult' applied at a critical point in in utero development. This then leads to an effect, for example diabetes or hypertension, which manifests itself in adult life. As the placenta is the regulator of nutrient composition and supply from mother to fetus and the source of hormonal signals that affect maternal and fetal metabolism, appropriate development of the placenta is crucial to normal fetal development. Placental function evolves in a carefully orchestrated developmental cascade throughout gestation. Disruption of this cascade can lead to abnormal development of the placental vasculature or of the trophoblast. Timing of a developmental 'insult' will be critical in consequent placental function and hence programming of the fetus. The 'insults' that alter placental development include hypoxia and abnormal maternal nutrient status, to which the placenta may adapt by alterations in transporter expression and activity to maintain fetal growth or by epigenetic regulation of placental gene expression. Hypoxia is physiological for organogenesis and placental tissue normally exists in a relatively hypoxic environment, but intrauterine growth restriction (IUGR) and pre-eclampsia are associated with a greater degree of trophoblast hypoxia. The metabolic activity of placental mitochondria leads to oxidative stress even in normal pregnancy which is exacerbated further in IUGR, diabetic and pre-eclamptic pregnancies and may also give nitrative stress known to lead to covalent modification and hence altered activity of proteins. Hypoxia, oxidative and nitrative stress all alter placenta development and may be a general underlying mechanism that links altered placental function to fetal programming.     

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.     

Monoclonal antibodies against maternal major histocompatibility complex class I molecules induce rapid abortion in mice.

PROBLEM: The role of antibodies against fetal or maternal antigens in maintaining or losing pregnancy is not clear. METHOD OF STUDY: Term-pregnant mice were injected with monoclonal antibodies against only fetal or fetal and maternal major histocompatibility complex class I molecules. The development of pregnancy was then followed. RESULTS: Antibodies against maternal, but not fetal, major histocompatibility complex class I molecules induced abortion in mice. The abortion occurred 6-8 hr after the administration of autoreactive antibodies. The abortion could only be induced after the formation of placenta. Antibodies against tumor necrosis factor-alpha could not prevent or postpone the abortion. Extensive bleeding has been detected in the placenta of aborting mice 3 hr after the administration of the antibodies. CONCLUSIONS: This study indicates that autoreactive antibodies present risk for pregnancy and that the damage leading to abortion induced by such antibodies most likely occurs at the maternal side of placenta.     

Calreticulin in human pregnancy and pre-eclampsia

Pre-eclampsia is a disorder of human pregnancy that involves pregnancy-induced maternal hypertension and proteinuria. Evidence indicates that pre-eclampsia involves widespread activation of maternal endothelial cells. Calreticulin is a ubiquitously expressed, multi-functional protein that has been shown to have both pro- and anti-inflammatory effects on cultured endothelial cells in vitro and in whole animals. In order to clarify the role of this protein in normal human pregnancy and in pre-eclampsia, this study has measured expression of calreticulin in maternal blood and in placenta in patients with pre-eclampsia and in control pregnancies. There was a significant increase (approximately 5-fold) in calreticulin in plasma in term pregnant women compared with women who were not pregnant. There was no difference, however, in calreticulin in plasma from women who were sampled at first trimester, second trimester and at term. In addition, there was a significant increase (approximately 50%) in calreticulin in plasma from pre-eclamptic women compared to controls. Calreticulin mRNA and protein expression in placenta were not changed between pre-eclampsia and control pregnancies. These novel results indicate that calreticulin is increased in peripheral maternal blood early in pregnancy and remains elevated throughout normal gestation and that there is a further increase in calreticulin in pre-eclampsia.