Reduction of In Vivo Placental Amino Acid Transport Precedes the Development of Intrauterine Growth Restriction in the Non-Human Primate.
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ABSTRACT: Intrauterine growth restriction (IUGR) is associated with reduced placental amino acid transport (AAT). However, it remains to be established if changes in AAT contribute to restricted fetal growth. We hypothesized that reduced in vivo placental AAT precedes the development of IUGR in baboons with maternal nutrient restriction (MNR). Baboons were fed either a control (ad libitum) or MNR diet (70% of control diet) from gestational day (GD) 30. At GD 140, in vivo transplacental AA transport was measured by infusing nine (13)C- or (2)H-labeled essential amino acids (EAAs) as a bolus into the maternal circulation at cesarean section. A fetal vein-to-maternal artery mole percent excess ratio for each EAA was measured. Microvillous plasma membrane (MVM) system A and system L transport activity were determined. Fetal and placental weights were not significantly different between MNR and control. In vivo, the fetal vein-to-maternal artery mole percent excess ratio was significantly decreased for tryptophan in MNR. MVM system A and system L activity was markedly reduced in MNR. Reduction of in vivo placental amino acid transport precedes fetal growth restriction in the non-human primate, suggesting that reduced placental amino acid transfer may contribute to IUGR.
Project description:Key pointsIntrauterine growth restriction (IUGR) is associated with perinatal morbidity and increased risk of lifelong disease, including neurodevelopmental impairment. Fatty acids (FA) are critical for normal brain development, although their transport across the placenta in IUGR pregnancies is poorly understood. The present study used a baboon model of IUGR (maternal nutrient restriction, MNR) to investigate placental expression of FA transport and binding proteins, and to determine gestational age-related changes in maternal and fetal plasma FA concentrations. We found MNR to be associated with increased placental expression of FA binding and transport proteins in late gestation, with fetal plasma FA concentrations that were similar to those of control animals. The present study is the first to report a profile of fetal and maternal plasma FA concentrations in a baboon model of growth restriction with data that suggest adaptation of placental transport to maintain delivery of critically needed FA.AbstractIntrauterine growth restriction (IUGR) is associated with specific changes in placental transport of amino acids, folate and ions. However, little is known about placental fatty acid (FA) transport in IUGR. We hypothesized that placental FA transport proteins (FATP) and FA binding proteins (FABP) are up-regulated and fetal plasma FA concentrations are decreased at term in a baboon model of IUGR. Pregnant baboons were fed control or maternal nutrient restricted (MNR) diet (70% of control calories) from gestation day (GD) 30 (term 184 days). Plasma and placental samples were collected at GD120 (control n = 8, MNR n = 9), GD140 (control n = 6, MNR n = 7) and GD170 (control n = 6, MNR n = 6). Placentas were homogenized, and syncytiotrophoblast microvillous plasma membrane (MVM) and basal plasma membranes (BM) were isolated. Protein expression of FABP1, 3, 4 and 5 (homogenate) and FATP2, 4, and 6 (MVM, BM) was determined by Western blotting. FA content in maternal and umbilical vein plasma was measured by gas chromatography-mass spectrometry. Placental FABP1 and FABP5 expression was increased in MNR compared to controls at GD170, as was MVM FATP2 and FATP6 expression at GD140 and FATP2 expression at GD170. BM FATP4 and FATP6 expression was increased in MNR at GD140. Fetal plasma FA concentrations were similar in controls and MNR. These data suggest the adaptation of placental transport when aiming to maintain delivery of critically needed FAs for fetal growth and brain development.
Project description:Intrauterine growth restriction (IUGR) is a pregnancy complication due to placental dysfunction that prevents the fetus from obtaining enough oxygen and nutrients, leading to serious mortality and morbidity risks. There is no treatment for IUGR despite having a prevalence of 3% in developed countries, giving rise to an urgency to improve our understanding of the disease. Applying biomechanics investigation on IUGR placental tissues can give important new insights. We performed pressure-diameter mechanical testing of placental chorionic arteries and found that in severe IUGR cases (RI > 90th centile) but not in IUGR cases (RI < 90th centile), vascular distensibility was significantly increased from normal. Constitutive modeling demonstrated that a simplified Fung-type hyperelastic model was able to describe the mechanical properties well, and histology showed that severe IUGR had the lowest collagen to elastin ratio. To demonstrate that the increased distensibility in the severe IUGR group was related to their elevated umbilical resistance and pulsatility indices, we modelled the placental circulation using a Windkessel model, and demonstrated that vascular compliance (and not just vascular resistance) directly affected blood flow pulsatility, suggesting that it is an important parameter for the disease. Our study showed that biomechanics study on placenta could extend our understanding on placenta physiology.
Project description:Maternal nutrient restriction causes the development of adult onset chronic diseases in the intrauterine growth restricted (IUGR) fetus. Investigations in mice have shown that either protein or calorie restriction during pregnancy leads to glucose intolerance, increased fat mass, and hypercholesterolemia in adult male offspring. Some of these phenotypes are shown to persist in successive generations. The molecular mechanisms underlying IUGR remain unclear. The placenta is a critical organ for mediating changes in the environment and the development of embryos. To shed light on molecular mechanisms that might affect placental responses to differing environments we examined placentas from mice that had been exposed to different diets. We measured gene expression and whole genome DNA methylation in both male and female placentas of mice exposed to either caloric restriction or ad libitum diets. We observed several differentially expressed pathways associated with IUGR phenotypes and, most importantly, a significant decrease in the overall methylation between these groups as well as sex-specific effects that are more pronounced in males. In addition, a set of significantly differentially methylated genes that are enriched for known imprinted genes were identified, suggesting that imprinted loci may be particularly susceptible to diet effects. Lastly, we identified several differentially methylated microRNAs that target genes associated with immunological, metabolic, gastrointestinal, cardiovascular, and neurological chronic diseases, as well as genes responsible for transplacental nutrient transfer and fetal development.
Project description:We recently reported the first evidence of placental endoplasmic reticulum (ER) stress in the pathophysiology of human intrauterine growth restriction. Here, we used a mouse model to investigate potential underlying mechanisms. Eif2s1(tm1RjK) mice, in which Ser51 of eukaryotic initiation factor 2 subunit alpha (eIF2?) is mutated, display a 30% increase in basal translation. In Eif2s1(tm1RjK) placentas, we observed increased ER stress and anomalous accumulation of glycoproteins in the endocrine junctional zone (Jz), but not in the labyrinthine zone where physiological exchange occurs. Placental and fetal weights were reduced by 15% (97 mg to 82 mg, p < 0.001) and 20% (1009 mg to 798 mg, p < 0.001), respectively. To investigate whether ER stress affects bioactivity of secreted proteins, mouse embryonic fibroblasts (MEFs) were derived from Eif2s1(tm1RjK) mutants. These MEFs exhibited ER stress, grew 50% slower, and showed reduced Akt-mTOR signalling compared to wild-type cells. Conditioned medium (CM) derived from Eif2s1(tm1RjK) MEFs failed to maintain trophoblast stem cells in a progenitor state, but the effect could be rescued by exogenous application of FGF4 and heparin. In addition, ER stress promoted accumulation of pro-Igf2 with altered glycosylation in the CM without affecting cellular levels, indicating that the protein failed to be processed after release. Igf2 is the major growth factor for placental development; indeed, activity in the Pdk1-Akt-mTOR pathways was decreased in Eif2s1(tm1RjK) placentas, indicating loss of Igf2 signalling. Furthermore, we observed premature differentiation of trophoblast progenitors at E9.5 in mutant placentas, consistent with the in vitro results and with the disproportionate development of the labyrinth and Jz seen in placentas at E18.5. Similar disproportion has been reported in the Igf2-null mouse. These results demonstrate that ER stress adversely affects placental development, and that modulation of post-translational processing, and hence bioactivity, of secreted growth factors contributes to this effect. Placental dysmorphogenesis potentially affects fetal growth through reduced exchange capacity.
Project description:BackgroundIntrauterine growth restriction (IUGR) is defined as a fetus that fails to achieve its genetically determined growth potential. The exact molecular mechanisms of placental insufficiency IUGR pathogenesis are a little known. Our goal was to identify key genes and gene co-expression modules related to placental insufficiency IUGR.MethodsWe used weighted gene co-expression network analysis (WGCNA) and protein-protein interaction (PPI) network analysis to examine the IUGR dataset GSE114691 from NCBI Gene Expression Omnibus. Core modules and hub nodes of the protein-protein interaction network were identified. A gene network was constructed and genes were classified by WGCNA into different modules. The validation of potential key genes was carried out using additional datasets (GSE12216 and GSE24129).ResultsWe identified in GSE114691 539 down regulated genes and 751 up regulated genes in placental tissues characteristic of placental insufficiency IUGR compared with non-IUGR, and defined 76 genes as hub nodes in the protein-protein interaction network. Genes in the key modules of the WGCNA network were most closely associated with placental insufficiency IUGR and significantly enriched in biological process such as cellular metabolic process and macromolecule metabolic process. We identified as key genes TGFB1, LEP, ENG, ITGA5, STAT5A, LYN, GATA3, FPR1, TGFB2, CEBPB, KLF4, FLT1, and PNPLA2. The RNA expression levels of ENG and LEP, as biomarkers, were validated.ConclusionA holistic gene expression profile of placental insufficiency IUGR has been generated and the key genes ENG and LEP has potential to serve as circulating diagnosis biomarkers and therapeutic targets for placental insufficiency IUGR.
Project description:Introduction Placental mesenchymal dysplasia is a rare vascular disease associated with intrauterine growth restriction, fetal demise as well as Beckwith-Wiedemann syndrome. Some neonates present hematologic abnormalities possibly related to consumptive coagulopathy and hemolytic anemia in the placental circulation. Case report We present a case of placental mesenchymal dysplasia in a fetus with intrauterine growth restriction and cerebellar hemorrhagic injury diagnosed in the 20th week of pregnancy. During 26th week, our patient had an intrauterine fetal demise in the context of gestational hypertension. We have detailed the ultrasound findings that made us suspect the presence of hematologic disorders during 20th week. Discussion We believe that the cerebellar hematoma could be the consequence of thrombocytopenia accompanied by anemia. If hemorrhagic damage during fetal life is found, above all associates with an anomalous placental appearance and with intrauterine growth restriction, PMD should be suspected along other etiologies.
Project description:The mechanisms underlying reduced fetal growth in response to maternal protein restriction are not well established. Maternal levels of insulin, IGF-I, and leptin are decreased in rats fed a low protein (LP) diet. Because these hormones stimulate placental amino acid transporters in vitro, we hypothesized that maternal protein restriction inhibits placental leptin, insulin/IGF-I, and mammalian target of rapamycin signaling and down-regulates the expression and activity of placental amino acid transporters. Pregnant rats were fed either an isocaloric low protein (LP, 4% protein) or control diet (18% protein) and studied at gestational day (GD)15, GD19, or GD21 (term 23). At GD19 and GD21, placental expression of phosphorylated eukaryotic initiation factor 4E binding protein 1 (Thr-36/46 or Thr-70) and phosphorylated S6 ribosomal protein (Ser-235/236) was decreased in the LP group. In addition, placental expression of phosphorylated S6 kinase 1 (Thr-389), phosphorylated Akt (Thr-308), and phosphorylated signal transducer and activator of transcription 3 (Tyr-705) was reduced at GD21. In microvillous plasma membranes (MVM) isolated from placentas of LP animals, protein expression of the sodium-coupled neutral amino acid transporter (SNAT)2 and the large neutral amino acid transporters 1 and 2 was reduced at GD19 and GD21. MVM SNAT1 protein expression was reduced at GD21 in LP rats. SNAT4 and 4F2 heavy chain expression in MVM was unaltered. System A and L amino acid transporter activity was decreased in MVM from LP animals at GD19 and GD21. In conclusion, maternal protein restriction inhibits placental insulin, mammalian target of rapamycin signaling, and signal transducer and activator of transcription 3 signaling, which is associated with a down-regulation of placental amino acid transporters. We speculate that maternal endocrine and metabolic control of placental nutrient transport reduces fetal growth in response to protein restriction.
Project description:BackgroundSexual dimorphism in placental physiology affects the functionality of placental adaptation during adverse pregnancy. Defects of placental function compromise fetal programming, affecting the offspring's adult life. However, studies focusing on the relationship between sex-specific placental adaptation and consequent fetal maldevelopment under sub-optimal uterus milieu are still elusive.MethodsHere, we investigated the effects of maternal lipopolysaccharide (LPS) exposure between placental sex. Pregnant ICR mice received intraperitoneal injection of phosphate-buffered saline or 100, 200, and 400 µg/kg LPS on the gestational day (GD) 15.5. To determine whether prenatal maternal LPS exposure resulted in complicated pregnancy outcomes, survival rate of embryos was calculated and the growth of embryos and placentas was examined. To elucidate global transcriptomic changes occurring in the placenta, total RNA-sequencing (RNA-seq) was performed in female and male placentas.ResultsLPS administration induced placental inflammation in both sexes at GD 17.5. Prenatal infection resulted in growth retardation in both sexes of embryos, and especially more prevalently in male. Impaired placental development was observed in a sex-specific manner. LPS 400 µg/kg reduced the percentage area of the labyrinth in females and junctional zone in males, respectively. RNA-sequencing revealed widespread sexually dimorphic transcriptional changes in placenta. In particular, representative changes were involved in biological processes such as trophoblast differentiation, nutrient/ion transporter, pregnancy, and immune system.ConclusionsOur results present the sexually dimorphic responses of placental physiology in intrauterine growth restriction model and provide tentative relationship further to be elucidated between sex-biased placental functional change and long-term effects on the offspring's later life.
Project description:UnlabelledHuman placental mesenchymal stromal cells (pMSCs) have never been investigated in intrauterine growth restriction (IUGR). We characterized cells isolated from placental membranes and the basal disc of six IUGR and five physiological placentas. Cell viability and proliferation were assessed every 7 days during a 6-week culture. Expression of hematopoietic, stem, endothelial, and mesenchymal markers was evaluated by flow cytometry. We characterized the multipotency of pMSCs and the expression of genes involved in mitochondrial content and function. Cell viability was high in all samples, and proliferation rate was lower in IUGR compared with control cells. All samples presented a starting heterogeneous population, shifting during culture toward homogeneity for mesenchymal markers and occurring earlier in IUGR than in controls. In vitro multipotency of IUGR-derived pMSCs was restricted because their capacity for adipocyte differentiation was increased, whereas their ability to differentiate toward endothelial cell lineage was decreased. Mitochondrial content and function were higher in IUGR pMSCs than controls, possibly indicating a shift from anaerobic to aerobic metabolism, with the loss of the metabolic characteristics that are typical of undifferentiated multipotent cells.SignificanceThis study demonstrates that the loss of endothelial differentiation potential and the increase of adipogenic ability are likely to play a significant role in the vicious cycle of abnormal placental development in intrauterine growth restriction (IUGR). This is the first observation of a potential role for placental mesenchymal stromal cells in intrauterine growth restriction, thus leading to new perspectives for the treatment of IUGR.
Project description:BackgroundGestational disorders such as intrauterine growth restriction (IUGR) and pre-eclampsia (PE) are main causes of poor perinatal outcomes worldwide. Both diseases are related with impaired materno-fetal nutrient transfer, but the crucial transport mechanisms underlying IUGR and PE are not fully elucidated. In this study, we aimed to identify membrane transporters highly associated with transplacental nutrient deficiencies in IUGR/PE.ResultsIn silico analyses on the identification of differentially expressed nutrient transporters were conducted using seven eligible microarray datasets (from Gene Expression Omnibus), encompassing control and IUGR/PE placental samples. Thereby 46 out of 434 genes were identified as potentially interesting targets. They are involved in the fetal provision with amino acids, carbohydrates, lipids, vitamins and microelements. Targets of interest were clustered into a substrate-specific interaction network by using Search Tool for the Retrieval of Interacting Genes. The subsequent wet-lab validation was performed using quantitative RT-PCR on placentas from clinically well-characterized IUGR/PE patients (IUGR, n = 8; PE, n = 5; PE+IUGR, n = 10) and controls (term, n = 13; preterm, n = 7), followed by 2D-hierarchical heatmap generation. Statistical evaluation using Kruskal-Wallis tests was then applied to detect significantly different expression patterns, while scatter plot analysis indicated which transporters were predominantly influenced by IUGR or PE, or equally affected by both diseases. Identified by both methods, three overlapping targets, SLC7A7, SLC38A5 (amino acid transporters), and ABCA1 (cholesterol transporter), were further investigated at the protein level by western blotting. Protein analyses in total placental tissue lysates and membrane fractions isolated from disease and control placentas indicated an altered functional activity of those three nutrient transporters in IUGR/PE.ConclusionsCombining bioinformatic analysis, molecular biological experiments and mathematical diagramming, this study has demonstrated systematic alterations of nutrient transporter expressions in IUGR/PE. Among 46 initially targeted transporters, three significantly regulated genes were further investigated based on the severity and the disease specificity for IUGR and PE. Confirmed by mRNA and protein expression, the amino acid transporters SLC7A7 and SLC38A5 showed marked differences between controls and IUGR/PE and were regulated by both diseases. In contrast, ABCA1 may play an exclusive role in the development of PE.