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The purity of tissue samples can affect the accuracy and utility of DNA methylation array analyses. This is particularly important for the placenta which is globally hypomethylated compared to other tissues. Placental villous tissue from early pregnancy terminations can be difficult to separate from non-villous tissue, resulting in potentially inaccurate results. We used several methods to identify mixed placenta samples using DNA methylation array datasets from our laboratory and those contained in the NCBI GEO database, highlighting the importance of determining sample purity during quality control processes.

Workshops are an integral component of the annual International Federation of Placenta Association (IFPA) meeting, allowing for networking and focused discussion related to specialized topics on the placenta. At the 2015 IFPA meeting (Brisbane, Australia) twelve themed workshops were held, three of which are summarized in this report. These workshops focused on various aspects of placental function, particularly in cases of placenta-mediated disease. Collectively, these inter-connected workshops highlighted the role of the placenta in fetal programming, the use of various biomarkers to monitor placental function across pregnancy, and the clinical impact of novel diagnostic and surveillance modalities in instances of late onset fetal growth restriction (FGR).

Introduction Proper placental function is essential for optimal fetal growth in utero. Placental transfer of nutrients to the fetus can be measured using radiolabelled tracers, but non-radioactive methods have potential advantages. This study aimed to develop a fluorescence-based method to measure placental glucose transport in mice. Methods Time course and localisation of the IRDye 800CW 2-deoxyglucose were recorded (Lumina IVIS Live Imaging System) following tail vein injection into anaesthetised late pregnant mice. Fluorescent signals in placental and fetal tissues were assessed after injecting conscious dams with 10 nmol IRDye 800CW 2-deoxyglucose (3, 30, 60, 120 min) or vehicle. Specificity of dye uptake was determined by comparing uptake of IRDye 800CW conjugated to 2-deoxyglucose or carboxylate, at 2 and 24 h. Finally, we assessed relationships of fetal size and umbilical blood flow velocities with relative dye uptake. Results In late pregnant mice, uterine fluorescent signal localised rapidly over placentas and remained consistent for >1 h. Signal intensity in whole and homogenised tissues increased in fetuses and decreased in placentas after 3 min and stabilised by 30 min post-injection. Relative fetal dye uptake at 2 and 24 h was greater in littermates with the highest compared to lowest placental efficiency; signals were similar for 2-deoxyglucose- or carboxylate-conjugated dyes. Relative fetal dye uptake correlated positively with fetal weight and placental efficiency and negatively with umbilical artery resistance indices. Conclusions Fetal uptake of IRDye 800CW correlates with markers of placental blood flow and fetal growth, but does not specifically measure placental glucose transport.

Placental function impacts growth and development with lifelong consequences for performance and health. We provide novel insights into placental development in bovine, an important agricultural species and biomedical model.Concepti with defined genetics and sex were recovered from nulliparous dams managed under standardized conditions to study placental gross morphological and histomorphological parameters at the late embryo (Day48) and early accelerated fetal growth (Day153) stages.Placentome number increased 3-fold between Day48 and Day153. Placental barrier thickness was thinner, and volume of placental components, and surface areas and densities were higher at Day153 than Day48. We confirmed two placentome types, flat and convex. At Day48, there were more convex than flat placentomes, and convex placentomes had a lower proportion of maternal connective tissue (P 0.01). However, this was reversed at Day153, where convex placentomes were lower in number and had greater volume of placental components (P 0.01- P 0.001) and greater surface area (P 0.001) than flat placentomes. Importantly, embryo (r = 0.50) and fetal (r = 0.30) weight correlated with total number of convex but not flat placentomes.Extensive remodelling of the placenta increases capacity for nutrient exchange to support rapidly increasing embryo-fetal weight from Day48 to Day153. The cellular composition of convex placentomes, and exclusive relationships between convex placentome number and embryo-fetal weight, provide strong evidence for these placentomes as drivers of prenatal growth. The difference in proportion of maternal connective tissue between placentome types at Day48 suggests that this tissue plays a role in determining placentome shape, further highlighting the importance of early placental development.

A significant proportion of children born preterm will experience some level of neurodevelopmental impairment. Changes in placental function have been observed with many antenatal conditions that are risk factors for preterm birth and/or poor neurodevelopment including fetal growth restriction and in-utero inflammation. This review will highlight placental factors that have been studied to understand the underlying mechanisms and identify biomarkers that lead to poor child neurodevelopmental outcomes. These include changes in gross morphological and histopathological structure and the placental inflammatory response to prenatal infection. Further, we will describe the placenta's role as both a barrier to maternally-derived bioactive substances critical for normal fetal brain development, such as cortisol, and a source of neuroactive steroids and neurotrophins known to have critical functions in neuronal proliferation, axonal growth, myelination and the regulation of apoptosis. Finally, emerging data supporting the potential utility of novel placental biomarkers in the early prediction of poor neurodevelopmental outcome in infants born both preterm and term will be discussed. These include the assessment of genetic variants (e.g. single nucleotide polymorphisms in placental tissue) and epigenetic biomarkers (e.g. placental microRNAs and placental DNA methylation). With the placenta the key tissue regulating the fetal environment, integration of observed changes in placental function with genetic and epigenetic variations may advance our ability to predict future infant health. Ultimately, this may facilitate targeted allocation of health resources with the aim of improving lifelong neurodevelopmental capability.

Introduction The pregnancy complications preeclampsia, gestational hypertension, small for gestational age infants (SGA) and pre-term birth (PTB) affect approximately 21% of all pregnancies. The Vascular Endothelial Growth Factor family (VEGF) is implicated in the pathogenesis of these complications. We aimed to evaluate the placental mRNA expression of VEGFA, PGF, FLT1 and KDR in pregnancies complicated by preeclampsia, gestational hypertension, SGA infants and pre-term birth. Method Placentae were collected at delivery from women with pregnancies complicated by preeclampsia ( n = 18), gestational hypertension ( n = 15), normotensive SGA infants ( n = 13), late spontaneous pre-term birth ( n = 10) and uncomplicated pregnancy ( n = 30). RNA was extracted and VEGFA, PGF, FLT1 and KDR expression were quantified using qRT-PCR. Kruskal Wallis test was used to compare placental mRNA expression in the adverse pregnancy outcome groups compared to uncomplicated term pregnancy. Results Compared to placental mRNA from uncomplicated pregnancies, VEGFA ( p = 0.006) , PGF ( p , KDR ( p FLT1 ( p = 0.02) mRNA were reduced in preeclamptic placentae; VEGFA ( p PGF ( p = 0.01) and KDR ( p = 0.008) mRNA were reduced in placentae from pregnancies complicated by gestational hypertension; VEGFA ( p = 0.03) mRNA was reduced in normotensive SGA pregnancies; VEGFA ( p = 0.008), PGF ( p = 0.01), KDR ( p = 0.04) and FLT1 ( p = 0.02) mRNA were reduced in placentae from late PTB. Conclusion VEGF family of angiogenic growth factor mRNA expression in the placenta is reduced in gestational hypertensive disorders, SGA and in pre-term birth.

Most research on the developmental origins of health and disease has implicated poor nutrition in the fetus, most often conferred by deficiencies in maternal nutrition, as an important causal factor that programmes offspring physiology for adult disease. Emerging evidence implicates interactions between genes and the environment that may help to explain why poor growth before birth is associated with a variety of adult onset diseases that appear in different individuals of the same birthweight. However, it is underappreciated that the placenta, particularly trophoblast invasion, is key to health of both the mother and child in both the short and long term and that the role of the father is more important than perhaps ever expected. Intrauterine growth restriction (IUGR) is but one of a continuum of several pregnancy complications that may be related and that may reflect the long term health of both parents and offspring. These include preeclampsia, pre-term birth and gestational diabetes, as well as IUGR. Polymorphisms in genes that regulate how the placenta invades maternal tissues, differentiates and functions and how the mother adapts to pregnancy have been identified as candidates that confer risk to pregnancy success. Potentially, pregnancy provides a window that gives clues to modifiable risk factors that should be addressed early to ameliorate late adult disease. Placentation and trophoblast invasion and its inhibitors in other species may provide new ideas for understanding what goes wrong in human pregnancy. Placentologists and clinicians may usefully collaborate to identify factors that predict risk for pregnancy complications and poor health later in life.

Common pregnancy complications are associated with impaired placental development. This study aimed to characterise the ontogeny of structural correlates of rabbit placental function, its expression of genes encoding components of the renin-angiotensin system (RAS), as well as 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD2) mRNA since these are known to be expressed by the placenta and are associated with pregnancy complications, including preeclampsia and intrauterine programming. Placentae were collected at gestational age (GA) 14, 21 and 28 (term = 32 days). Gene expression was analysed using real time PCR and placental structures were quantified via image analyses. The volume densities and volumes of trophoblast, fetal capillaries, maternal blood space, surface density and surface area of trophoblast all progressively increased, while the arithmetic mean barrier thickness of trophoblast decreased across gestation. Maternal plasma renin activity (PRA) was positively correlated with volumes of trophoblast and maternal blood space, surface density and surface area of trophoblast. Placental renin mRNA declined (down arrow 62%; P

Workshops are an important part of the annual meeting of the International Federation of Placenta Associations (IFPA). At IFPA Meeting 2009 diverse topics were discussed in twelve themed workshops. Topics covered included: immune response to pregnancy; signaling between fetus and placenta; bioactive lipids in placenta; placenta in agricultural species; epigenetics and placentation; trophoblast deportation; glucocorticoids and placental function; endothelium; placental transport; genes and placenta; uteroplacental blood flow and placental stem cells. This report is a full summary of the various topics covered.

Placental insufficiency is thought to be a key factor in many cases of intrauterine growth restriction which complicates about 6% of pregnancies in western countries. Understanding the molecular control of placental and fetal growth is essential to identifying diagnostic and therapeutic targets to improve pregnancy success. Insulin-like growth factor (IGF)-I and IGF-II gene ablation or maternal food restriction reduce tissue and circulating IGF abundance in the fetus, placenta and mother and are associated with both placental and fetal growth restriction. Conversely, in vivo treatment of the pregnant guinea pig with IGF-I or IGF-II from early to mid pregnancy increases fetal weight and enhances placental transport near term. IGF-II, and an IGF2R specific analogue, enhanced placental structural differentiation, whereas IGF-I altered maternal body composition. These outcomes demonstrate endocrine roles within the mother for both IGFs, as well as autocrine/paracrine effects of IGF-II in enhancing placentation and pregnancy success. Therefore, factors that alter placental expression of IGF-II, or maternal circulating IGF-I or IGF-II in early pregnancy may affect placental exchange function late in gestation when the demands of the fetus escalate. IGF-II within the fetus may also signal its nutrient demands to the placenta to improve its function to suit. Therefore each IGF of endocrine and local origin has important, but distinct, roles in placental development and function.

Successful placental development and the associated changes to the decidual vasculature during early pregnancy are critical to pregnancy outcome. This study utilised immunohistochemistry to provide a photomicrographic account of trophoblast invasion, as well as the changes in the uterine vasculature in the decidua from days 5.5 to 10.5 of murine pregnancy. The pattern of trophoblast invasion during this time is particularly interesting because, unlike in humans, murine trophoblast giant cells (TGCs) do not invade the endometrium individually but remain in close contact with the expanding giant cell layer. Therefore, trophoblast cells are unlikely to play a direct role in remodelling the maternal vessels in early to mid pregnancy. Nevertheless, the decidual vessels appear to undergo extensive angiogenesis and remodelling to form a network of dilated vessels that presumably maximize placental blood supply. Importantly, the vessels closest to the conceptus lacked a smooth muscle layer throughout early pregnancy and therefore cannot strictly be described as spiral arterioles. TGCs may secrete molecules that can act to induce these vascular changes. Here we show that insulin-like growth factor-II (IGF-II) is expressed throughout early pregnancy in the entire conceptus including trophoblast cells, supporting its role in promoting early placental growth. In addition, the co-localisation of IGF-II and both IGF receptors in the developing blood vessels and/or adjacent stromal cells in the mesometrial, but not in the anti-mesometrial, decidua suggest that IGF-II, upon binding to one of these receptors, may play a role in both decidual angiogenesis and placental differentiation.

The insulin-like growth factors (IGF-I and -II) and their binding proteins (IGFBP-1 to -6) are major players throughout gestation, being involved in implantation, placentation and fetal development. In human pregnancy, alterations of the IGF/IGFBP system are associated with serious complications such as intrauterine growth restriction (IUGR) and pre-eclampsia [1 and 2]. Work on the post-translational modification of IGFBP-1 and its role in trophoblast invasion and fetal growth has furthered our understanding of normal and abnormal pregnancy. Although there are species differences as well as similarities, recent work on transgenic mice offers insight into the IGF/IGFBP system in gestation. The use of conditional knockout of the various components of the IGF/IGFBP system represents a further step in this direction. The aim of this workshop was to bring together these various strands of research.

Size at birth, which reflects foetal growth, is an important predictor of perinatal survival and adult health. The mechanisms responsible for this must therefore involve the major determinants of growth before birth, such as the interaction between the foetal genome and the supply of essential substrates from the placenta and determinants of the latter, including the availability of oxygen and nutrients within the mother. The long-term consequences of impaired foetal growth on adult health, termed programming, are thought to be due to the effects of a perturbed uterine environment on foetal structure and physiology, which result in permanently altered function. Gene ablation studies have shown that the insulin-like growth factors (IGFs) play a significant role in the control of both foetal and placental growth and maturation. IGF-I null mutation results in severe growth restriction of the foetus (Liu et al., 1993), while IGF-II gene deletion has similar effects on the foetus, but also restricts the placenta (Baker et al., 1993) and both cause altered differentiation and function before and after birth. The aim of this workshop was to review recent understanding of the roles of the IGFs and their binding proteins in placental and foetal development in the context of programming. In particular, a goal was to elucidate the interaction of the maternal and foetal IGF axes with the placenta and foetus in both normal and perturbed pregnancy.

There is inconsistent use of Matrigel for experiments with the HTR8/SVneo first trimester trophoblast and other cell lines. We quantified the effects of Matrigel on the expression of genes considered to be markers of extravillous cytotrophoblast (EVT) differentiation and invasive potential. Culture on Matrigel promoted formation of "endothelial-like" tubes and reduced mRNA expression of matrix metalloproteinase 2 (MMP2), cytokeratin 7 (KRT7) and integrin alpha 1 (ITGA1), while increasing VE-cadherin (CDH5) expression consistent with a vascular phenotype. This process may constitute part of the endothelial cell mimicry exhibited by endovascular EVTs invading the maternal spiral arteries. HTR8/SVneo appears to be phenotypically polymorphic and adopt endovascular morphology on Matrigel. Refereed/Peer-reviewed

Maternal feed restriction may restrict fetal growth in part indirectly by impairing placental functional development. Such actions could be mediated by the insulin-like growth factors (IGF), which are important modulators of placental growth and differentiation and more generally, are influenced by nutrient availability. While a role for the fetal IGF axis has been demonstrated, less is known of the influence, if any, of that in the mother. This study aimed to determine whether alterations in the maternal IGF axis and placental functional and structural development due to maternal food restriction are related. We therefore examined the associations between placental structural parameters, the ratios of maternal to fetal plasma glucose and fetal to maternal plasma urea concentration, and maternal circulating IGF-I, IGF-II and IGFBP-2 in ad libitum fed and food restricted (70–90 per cent of the ad libitum intake) pregnant guinea pigs. In mid-gestation, fetal weight ( r =0.65, P =0.008, n =17), volume of the maternal blood space ( r =0.58, P =0.048, n =17), and surface density of syncytiotrophoblast ( r =0.65, P =0.023, n =17), were positively correlated, and syncytiotrophoblast thickness was negatively correlated, with maternal plasma IGF-II concentration ( r =−0.69, P =0.014, n =17). Late in gestation, fetal weight, placental weight and total exchange surface area in the placenta were each negatively correlated with maternal plasma IGFBP-2 concentration (all P 0.01), while the arithmetic mean thickness of syncytiotrophoblast was positively correlated with maternal plasma IGFBP-2 concentration. Late in gestation, the ratio of maternal to fetal plasma glucose was positively correlated with fetal weight ( r =0.54, P =0.038, n =15) and the ratio of fetal to maternal plasma urea concentration was positively correlated with placental weight ( r =0.52, P =0.046, n =15). Maternal feed restriction reduced the ratio of maternal plasma IGF-II to IGFBP-2 in late gestation by 75 per cent ( P =0.001) and this ratio was positively correlated with fetal weight ( r =0.56, P =0.01, n =20), placental weight ( r =0.59, P =0.006), placental diameter ( r =0.621, P =0.003), placental volume ( r =0.57, P =0.009), weight of trophoblast ( r =0.51, P =0.037), weight of fetal capillaries ( r =0.49, P =0.046), syncytiotrophoblast surface density ( r =0.611, P =0.009) and negatively correlated with syncytiotrophoblast thickness ( r =−0.55, P =0.021). Our results suggest that in mid-pregnancy, maternal circulating IGF-II promotes placental structural development, while later in pregnancy, IGFBP-2 inhibits it, and their relative abundance and interaction strongly influences placental structure and function near term.

The extent to which maternal nutrition influences fetal growth through effects on placental functional development is unclear. Poor maternal nutrition is a major cause of poor fetal growth which increases neonatal morbidity and mortality, and may also increase the risk of several adult-onset diseases. We have therefore characterized the ontogeny of structural determinants of function in the placenta in guinea-pigs fed ad libitum or food restricted from before and during pregnancy. Guinea-pigs were killed at days 30 and 60 (term=67 days) of pregnancy. In ad libitum fed animals, the surface density (surface area/g placental labyrinth), which is a measure of the convolution of the exchange surface, doubled, while total surface area increased 18-fold between mid and late gestation. Concomitantly, the arithmetic mean barrier thickness to diffusion across trophoblast decreased by 68 per cent. Late in gestation, food restriction reduced the proportion of the placenta devoted to exchange (labyrinth) by 70 per cent (P< 0.04) and the weight of the placental labyrinth by 45 per cent (P=0.001). Maternal food restriction also reduced the total placental surface area for exchange by 36 per cent at day 30 (P=0.02) and 60 per cent at day 60 (P< 0.0005) of gestation, and the surface density of trophoblast by 36 per cent at day 30 (P=0.01) and 29 per cent at day 60 (P=0.005) of gestation. The arithmetic mean barrier thickness for diffusion was increased by maternal food restriction at both gestational ages (day 30, +37 per cent, P=0.008, and day 60, +40 per cent, P=0.01). These findings suggest that maternal food restriction not only reduces fetal and placental weights, but also induces structural alterations in the placenta that indicate functional impairment beyond what would be expected for the reduction in its weight.

Introduction Early (EPE) and late (LPE) onset preeclampsia are increasingly being recognized as two distinct disorders. Placental vascular defects are more common in EPE. Hypoxia Inducible Factor 1α (HIF1α) regulates the expression of many angiogenic growth factors in the placenta. We studied the association of two polymorphisms in the HIF1α gene (rs11549465 and rs10873142) with EPE and LPE. Methods 175 nulliparous Sinhalese women with preeclampsia and 171 normotensive women matched for age, ethnicity, parity and BMI were recruited at two tertiary care hospitals in Colombo. Preeclampsia was diagnosed using international guidelines. DNA extracted from peripheral blood was genotyped using Sequenom MassARRAY. Results HIF1α rs11549465 dominant model and T allele were reduced in women who developed EPE compared to controls [P = 0.002, OR (95% CI) = 0.3 (0.1–0.7)], in preeclamptic women who delivered small for gestational age babies [P = 0.02, OR (95% CI) = 0.5 (0.2–0.9)] compared to controls and in women who developed EPE compared to those who developed LPE [P = 0.006, OR (95% CI) = 0.3 (0.1–0.7)]. Conclusion Our results demonstrate a protective effect of the T allele in LPE and normal pregnancy, which is relatively lacking in EPE due to low prevalence of this protective allele. HIF1α rs11549465 T allele was previously demonstrated to be associated with a higher transcriptional activity and increased angiogenesis. Inherited susceptibility to increased HIF1α expression resulting in the up-regulation of angiogenic genes may mediate a protective effect in normal pregnancy and pregnancy complicated by LPE.

The placenta has arisen relatively recently and is among the most rapidly evolving tissues in mammals. Several different placental barrier and structure types appear to have independently evolved common functional features. Specific patterns of gene expression that determine placental development in humans are predicted to be accompanied by specific profiles of epigenetic modification. However, the stratification of epigenetic modifications into those involved in conserved aspects of placental function, versus those involved in divergent placental features, has yet to begin. As a first step towards this goal, we have investigated the methylation status of a small number of gene-specific methylation events recently identified in human placenta, in a panel of placental tissue from baboon, marmoset, cow, cat, guinea pig and mouse. These represent disparate placental barrier types and structures. In this study we hypothesized that specific epigenetic markings may be associated with placental barrier type or function, independent of phylogeny. However, in contrast to our predictions, the majority of gene-specific methylation appears to track with phylogeny, independent of placental barrier type or other structural features. This suggests that despite the likelihood of epigenetic modification playing a role in the functioning and evolution of different placental subtypes, there is no evidence for an involvement of the gene-specific methylation profiles we have identified, in specifying these differences. Further studies, examining larger numbers of epigenetic modifications across phylogeny, are required to define the role of specific epigenetic modifications in the evolution of distinct placental structures.

In guinea pigs, maternal insulin-like growth factor (IGF) infusion in early-pregnancy enhances placental transport near-term, increasing fetal growth and survival. The effects of IGF-II, but not IGF-I, appear due to enhanced placental labyrinthine (exchange) development. To determine if the type-2 IGF receptor (IGF2R) mediates these distinct actions of exogenous IGF-II in the mother, we compared the impact of IGF-II with an IGF-II analogue, Leu(27)-IGF-II, which only binds the IGF2R. IGF-II, Leu(27)-IGF-II (1mg/kg per day.sc) or vehicle were infused from days 20-38 of pregnancy (term = 67 days) and placental structure and uptake and transfer of [(3)H]-methyl-D-glucose (MG) and [(14)C]-amino-isobutyric acid (AIB) and fetal growth and plasma metabolites, were measured on day 62. Both IGF-II and Leu(27)-IGF-II increased the volume of placental labyrinth, trophoblast and maternal blood space within the labyrinth and total surface area of trophoblast for exchange, compared to vehicle. Leu(27)-IGF-II also reduced the barrier to diffusion (trophoblast thickness) compared to vehicle and IGF-II. Both IGF-II and Leu(27)-IGF-II increased fetal plasma amino acid concentrations and placental transfer of MG to the fetus compared to vehicle, with Leu(27)-IGF-II also increasing AIB transport compared with vehicle and IGF-II. In addition, Leu(27)-IGF-II increased fetal weight compared to vehicle. In conclusion, maternal treatment with IGF-II or Leu(27)-IGF-II in early gestation, induce similar placental and fetal outcomes near term. This suggests that maternal IGF-II in early gestation acts in part via the IGF2R to persistently enhance placental functional development and nutrient delivery and promote fetal growth.

The human first trimester placenta experiences a low oxygen environment. The hypoxia inducible factors (HIFs) mediate the response to low oxygen, inducing genes such as insulin-like growth factor (IGF)-II. Interestingly, IGF-II has been shown to promote placental growth and function. Currently, the interaction between oxygen, IGF-II and HIFs in the regulation of trophoblast behaviour are unclear. Murine implantation sites from days 5.5-10.5 were collected for immunohistochemical analyses. Use of the hypoxia marker pimonidazole indicated that the early mouse implantation site is exposed to low oxygen levels similar to those seen in the early human placenta. HIF-1alpha protein immunostaining was also observed in the implantation site. Culturing murine ectoplacental cones in decreasing oxygen concentrations (20%, 5% and 1% O(2)), either with or without the addition of IGF-II, induced complex responses by trophoblasts in terms of their migration and differentiation. Following 3 days exposure to low oxygen there was reduced EPC outgrowth, reduced Igf2 and increased Tpbp mRNA levels, suggesting commitment to the spongiotrophoblast lineage. In addition, Hif-1alpha mRNA levels were decreased, whilst Hif-2alpha mRNA was unchanged. This decrease in Hif-1alpha may be due to the observed increase in antisense (as) Hif-1alpha mRNA levels in 1% cultures. Furthermore, expression of Hif-2alpha and the HIF target genes: asHif-1alpha, Vegf and Slc2a1 were reduced under low oxygen with the addition of IGF-II. In conclusion, Hif-1alpha and Hif-2alpha are differentially regulated by oxygen and IGF-II in cultured trophoblast cells and asHif-1alpha may mediate the response to prolonged hypoxia in murine trophoblasts.

Prabha Andraweera, Gustaaf Dekker, Kathy Gatford, Shalem Leemaqz, Lesley McCowan, Roahn Jayasekara, Vajira Dissanayake, Claire Roberts

Placental morphogenesis and nutrient transfer function are regulated by growth factors at the foeto-maternal interface. Interleukin (IL)-10, expressed in the decidua and placenta, is implicated in regulating extravillous cytotrophoblast invasion through inhibiting matrix metalloproteinase expression and influencing the quality of the maternal immune response. Our laboratory has previously found that IL-10 deficiency in both the mother and foetus increases foetal weight at day 18 without altering placental weight suggesting that the placenta has a greater functional capacity when IL-10 is absent. The present study has used IL-10 null mutant (IL-10−/−) mice to investigate the role of IL-10 in placental development. Placental structure was assessed in adult virgin IL-10−/− or wild-type (IL-10+/+) mice mated with males of the same genotype and sacrificed at day 18 of gestation. Mid-sagittal cross sections of placental tissue were stained with Masson's trichrome or immuno-labelled with MTS-12 and pan-cytokeratin reactive antibodies to identify foetal endothelial cells and trophoblasts, respectively, and examined with video image analysis. IL-10 deficiency increased the total cross sectional area of the placenta by 28 per cent (IL-10−/− n =22 placentae from 8 dams, IL-10+/+ n =21 placentae from 9 dams, P =0.026), principally through increasing the cross sectional area of placental labyrinth by 37 per cent ( P =0.025). The proportion of maternal blood space in the labyrinth was increased by 26 per cent ( P =0.001) and that of trophoblast was decreased by 16 per cent ( P =0.001) in IL-10−/− placentae. The surface area of trophoblast per gram of labyrinth was increased by 41 per cent ( P =0.0005) in IL-10−/− placentae. In the absence of IL-10, structural correlates of placental function are enhanced consistent with concomitant increases in foetal growth. These data indicate that IL-10 is a regulator of placental morphogenesis, acting to retard expansion of the placental labyrinth and to modify the architecture of the maternal blood sinuses. Since previous studies have paradoxically shown that postnatal growth is impaired in IL-10 null mutants, these observations are consistent with a role for IL-10 in regulating placental development and foetal programming.