Placental Gene Expression in a Rat ‘Model’ of Placental Insufficiency

Proteomic analysis of amniotic fluid to identify potential targets predicting preterm delivery

Preterm delivery is a common complication of pregnancy which leads to significant neonatal mortality and morbidity. Identifying predictive markers linked to spontaneous preterm delivery (SPTD) is important for effective treatment and prevention of PTD. To explore potential biomarkers related to SPTD, we performed proteomics analysis in amniotic fluid (AF). In total, we enrolled 30 pregnant women with singleton gestation who underwent clinically indicated amniocentesis at 15-24 weeks of gestation. LC-MS analysis was used to analyze the AF samples of 10 women with SPTD < 34 weeks after cervix cerclage (Preterm group), 10 women with term delivery (TD) ≥ 34 weeks after cervix cerclage (Term group), and 10 women who delivered at term (Normal group). ELISA validation was performed for candidate proteins in a second independent cohort. As a result, we identified 44 differentially expressed proteins (DEPs, P < 0.05) via proteomic analysis, and based on that, 9 primary pathways were also determined in SPTD. Results of the ELISA assay confirmed that the increased concentration of Serpin A1, decreased concentrations of Renin and IGFBP4 were significantly associated with SPTD at ≤34 weeks.

Human Plasma Proteome During Normal Pregnancy

The human plasma proteome is underexplored despite its potential value for monitoring health and disease. Herein, using a recently developed aptamer-based platform, we profiled 7288 proteins in 528 plasma samples from 91 normal pregnancies (Gene Expression Omnibus identifier GSE206454). The coefficient of variation was <20% for 93% of analytes (median 7%), and a cross-platform correlation for selected key angiogenic and anti-angiogenic proteins was significant. Gestational age was associated with changes in 953 proteins, including highly modulated placenta- and decidua-specific proteins, and they were enriched in biological processes including regulation of growth, angiogenesis, immunity, and inflammation. The abundance of proteins corresponding to RNAs specific to populations of cells previously described by single-cell RNA-Seq analysis of the placenta was highly modulated throughout gestation. Furthermore, machine learning-based prediction of gestational age and of time from sampling to term delivery compared favorably with transcriptomic models (mean absolute error of 2 weeks). These results suggested that the plasma proteome may provide a non-invasive readout of placental cellular dynamics and serve as a blueprint for investigating obstetrical disease.

Renal functional, transcriptome, and methylome adaptations in pregnant Sprague Dawley and Brown Norway rats

Pregnancy induces maternal renal adaptations that include increased glomerular filtration rate and renal blood flow which can be compromised in obstetrical complications such as preeclampsia. Brown Norway (BN) rat pregnancies are characterized by placental insufficiency, maternal hypertension, and proteinuria. We hypothesized that BN pregnancies would show renal functional, anatomical, or molecular features of preeclampsia. We used the Sprague-Dawley (CD) rat as a model of normal pregnancy. Pregnancy increased the glomerular filtration rate by 50% in CD rats and 12.2% in BN rats compared to non-pregnancy, and induced proteinuria only in BN rats. BN pregnancies showed a decrease in maternal plasma calcitriol levels, which correlated with renal downregulation of 1-alpha hydroxylase and upregulation of 24-hydroxylase. RNA sequencing revealed that pregnancy induced 297 differentially expressed genes (DEGs) in CD rats and 174 DEGs in BN rats, indicating a 70% increased response to pregnancy in CD compared to BN rats. Pregnancy induced activation of innate immune pathways such as ‘Role of Pattern Recognition Receptors’, and ‘Interferon signaling’ with interferon regulatory factor 7 as a common upregulated upstream factor in both rat strains. Comparison of rat strain transcriptomic profiles revealed 475 DEGs at non-pregnancy and 569 DEGs at pregnancy with 205 DEGs shared at non-pregnancy (36%), indicating that pregnancy interacted with rat strain in regulating 64% of the DEGs. Pathway analysis revealed that pregnancy induced a switch in renal transcriptomics in BN rats from ‘inhibition of renal damage’ to ‘acute phase reaction’, ‘recruitment of immune cells’ and ‘inhibition of 1,25-(OH)2-vitamin D synthesis’. Key upstream regulators included peroxisome-proliferator-activated receptor alpha (PPARA), platelet-derived growth factor B dimer (PDGF-BB), and NF-kB p65 (RELA). DNA methylome profiling by reduced representation bisulfite sequencing studies revealed that the DEGs did not correlate with changes in promoter methylation. In sum, BN rat kidneys respond to pregnancy-specific signals with an increase in pro-inflammatory gene networks and alteration of metabolic pathways including vitamin D deficiency in association with mild proteinuria and blunted GFR increase. However, the lack of glomerular endotheliosis and mild hypertension/proteinuria in pregnant BN rats limits the relevance of this rat strain for preeclampsia research.

Increased Placental Anti-Oxidant Response in Asymptomatic and Symptomatic COVID-19 Third-Trimester Pregnancies

Despite Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) -induced Oxidative Stress (OxS) being well documented in different organs, the molecular pathways underlying placental OxS in late-pregnancy women with SARS-CoV-2 infection are poorly understood. Herein, we performed an observational study to determine whether placentae of women testing positive for SARS-CoV-2 during the third trimester of pregnancy showed redox-related alterations involving Catalase (CAT) and Superoxide Dismutase (SOD) antioxidant enzymes as well as placenta morphological anomalies relative to a cohort of healthy pregnant women. Next, we evaluated if placental redox-related alterations and mitochondria pathological changes were correlated with the presence of maternal symptoms. We observed ultrastructural alterations of placental mitochondria accompanied by increased levels of oxidative stress markers Thiobarbituric Acid Reactive Substances (TBARS) and Hypoxia Inducible Factor-1 α (HIF-1α) in SARS-CoV-2 women during the third trimester of pregnancy. Importantly, we found an increase in placental CAT and SOD antioxidant enzymes accompanied by physiological neonatal outcomes. Our findings strongly suggest a placenta-mediated OxS inhibition in response to SARS-CoV-2 infection, thus contrasting the cytotoxic profile caused by Coronavirus Disease 2019 (COVID-19).

Modeling Trophoblast Cell-Guided Uterine Spiral Artery Transformation in the Rat

The rat possesses hemochorial placentation with deep intrauterine trophoblast cell invasion and trophoblast-guided uterine spiral artery remodeling, which resembles human placentation. Uterine spiral arteries are extensively remodeled to deliver sufficient supply of maternal blood and nutrients to the developing fetus. Inadequacies in these key processes negatively impact fetal growth and development. Recent innovations in genome editing combined with effective phenotyping strategies have provided new insights into placental development. Application of these research approaches has highlighted both conserved and species-specific features of hemochorial placentation. The review provides foundational information on rat hemochorial placental development and function during physiological and pathological states, especially as related to the invasive trophoblast cell-guided transformation of uterine spiral arteries. Our goal is to showcase the utility of the rat as a model for in vivo mechanistic investigations targeting regulatory events within the uterine-placental interface.

Mycotoxin ingestion during late gestation alters placentome structure, cotyledon transcriptome, and fetal development in pregnant sheep

Ergot alkaloids, a class of mycotoxins, induce vasoconstriction when consumed by animals and humans. Pregnant ewes (n = 16; 81.2 kg ± 7.7) were assigned fed endophyte-infected tall fescue seed (E+; 4.14 μg ergovaline + ergovalinine/g seed) or a control diet (CON; 0 μg ergovaline + ergovalinine) for increasing duration during late gestation (from gd86 to gd110 or gd133) to examine changes in placentome morphology and mRNA transcriptome, and fetal development. Exposure to E+ fescue reduced serum prolactin concentrations at gd110 and gd133 demonstrating treatment efficacy. For control ewes, cotyledon and total placentome weights decreased with advancing gestation due to remodeling of placental tissues; however, cotyledon and placentome weight did not change with advancing gestation in E+ fed ewes. Fetal brain sparing was evident in E+ exposed fetuses at gd110 and gd133 compared to CON, which demonstrates asymmetrical growth and intrauterine growth restriction. Mycotoxin exposure (E+) resulted in differential expression of 22 genes in the cotyledon tissue at gd110 but only one gene at gd133 compared to CON. These results suggest that the response to mycotoxin exposure in the pregnant sheep model has an immediate impact on placental remodeling and fetal development that persists throughout the duration of the exposure period.

ACE2: a key modulator of the renin-angiotensin system and pregnancy

Angiotensin-converting enzyme 2 (ACE2) is a membrane-bound protein containing 805 amino acids. ACE2 shows approximately 42% sequence similarity to somatic ACE but has different biochemical activities. The key role of ACE2 is to catalyze the vasoconstrictor peptide angiotensin (ANG) II to Ang-(1–7), thus regulating the two major counterbalancing pathways of the renin-angiotensin system (RAS). In this way, ACE2 plays a protective role in end-organ damage by protecting tissues from the proinflammatory actions of ANG II. The circulating RAS is activated in normal pregnancy and is essential for maintaining fluid and electrolyte homeostasis and blood pressure. Renin-angiotensin systems are also found in the conceptus. In this review, we summarize the current knowledge on the regulation and function of circulating and uteroplacental ACE2 in uncomplicated and complicated pregnancies, including those affected by preeclampsia and fetal growth restriction. Since ACE2 is the receptor for SARS-CoV-2, and COVID-19 in pregnancy is associated with more severe disease and increased risk of abnormal pregnancy outcomes, we also discuss the role of ACE2 in mediating some of these adverse consequences. We propose that dysregulation of ACE2 plays a critical role in the development of preeclampsia, fetal growth restriction, and COVID-19-associated pregnancy pathologies and suggest that human recombinant soluble ACE2 could be a novel therapeutic to treat and/or prevent these pregnancy complications.

Roles of tetraspanins during trophoblast development: bioinformatics and new perspectives

Tetraspanins are a superfamily of membrane proteins found in all eukaryotic organisms. They act as scaffold molecules that regulate the traffic and function of other membrane/signaling proteins, resulting in important downstream cellular consequences. The aim of this work was to use transcriptomes and bioinformatics analysis to identify the tetraspanins (and their partners) involved in trophoblast differentiation. We built a protein-protein interaction network around tetraspanins which revealed that tetraspanins CD9, CD81, and CD82 show a specific expression during trophoblast differentiation. These proteins appeared to be interconnected and to recruit several membrane partners which include integrins, immune-related molecules, and a variety of receptors. During weeks 8 to 24, a CD9 expression trajectory was identified in extravillous trophoblasts, and a website was developed: ( https://extravillous.shinyapps.io/CD9humanEVT/ ). In conclusion, CD81 may, together with CD9 and CD82, be interconnected in controlling trophoblast invasion in the endometrium. CD9 expression trajectory in extravillous trophoblast between weeks 8 and 24 shows the involvement of CD9 in cell adhesion and migration.

SARS-CoV-2, Endothelial Dysfunction, and the Renin-Angiotensin System (RAS): A Potentially Dangerous Triad for the Development of Pre-Eclampsia

SARS-CoV-2 represents the greatest epidemiological, clinical, and social challenge the human being has had to face in this century. SARS-CoV-2 is not merely a respiratory virus, as its target cells range from upper airway respiratory cells to pulmonary cells but also and above all to the cardiovascular cells, such as pericytes and endothelial cells. Indeed, the pathology related to SARS-CoV-2, COVID-19, may be defined as a thromboinflammatory syndrome in its most severe form, characterized by sepsis-induced coagulopathy (SIC) and disseminated intravascular coagulopathy (DIC), which is prevalent in individuals already presenting a chronic level of inflammation (e.g., obese individuals, elderly) and hypertension. Pregnancy is not only an inflammatory-prone condition but is characterized by a consistent rearrangement of the blood circulation and coagulation profile. Cardiac output increases while arterial systolic and diastolic pressure decrease, regardless of the activation of the RAS system. ACE2, the SARS-CoV-2 entry receptor into the host cells, which transforms Ang II in Ang 1–7, is highly expressed in endothelial, smooth muscle cells and pericytes of placental villi, regulating blood pressure and fetal development. Pre-eclampsia is a pregnancy disorder characterized by hypertension and low levels of ACE2, endothelial dysfunction, and a high production of pro-inflammatory cytokines, resembling COVID-19 manifestations. Whereas pre-eclampsia and COVID-19 have overlapping clinical features, a role for SARS-CoV-2 as a leading cause of pre-eclampsia in COVID-19 positive pregnant women has not been clarified yet. In this mini-review, we will explore the possibility of the existence of such a link, focusing on the role of endothelial dysfunction and RAS in both pre-eclampsia and SARS-CoV-2-induced COVID-19 pathogenesis.

Increased placental expression of angiotensin-converting enzyme 2, the receptor of SARS-CoV-2, associated with hypoxia in twin anemia-polycythemia sequence (TAPS)

INTRODUCTION

Recent reports suggest SARS-CoV-2, the virus causing COVID-19, may be transmittable from pregnant mother to placenta and fetus, albeit rarely. The efficacy of vertical transmission of SARS-CoV-2 critically depends on the availability of its receptor, ACE2, in the placenta. In the present study, we tested the hypothesis that placental ACE2 expression is oxygenation-dependent by studying the expression of ACE2 and associated cell entry regulators in the monochorionic twin anemia-polycythemia (TAPS) placenta, a model of discordant placental oxygenation.

METHODS

We performed a retrospective comparative immunohistochemical, immunofluorescence and Western blot analysis of ACE2, TMPRSS2 and Cathepsin B expression in anemic and polycythemic territories of TAPS placentas (N = 14).

RESULTS

ACE2 protein levels were significantly higher in the anemic twin territories than in the corresponding polycythemic territories, associated with upregulation of the key ACE2-related cell entry regulators, TMPRSS2 and Cathepsin B, immunolocalized to villous trophoblastic and stromal cells. Cellular colocalization of ACE2 and TMPRSS2, suggestive of functionality of this cell entry axis, was demonstrated by double immunofluorescence studies.

DISCUSSION

Placental hypoxia is associated with upregulation of ACE2 expression, concomitant with increased expression of its key cell entry proteases. ACE2-regulated placental functions, both infection- and non-infection related, may be highly oxygenation-dependent.

Monochorionic twins with selective fetal growth restriction: insight from placental whole-transcriptome analysis

BACKGROUND

The underlying pathomechanism in placenta-related selective fetal growth restriction in monochorionic diamniotic twin pregnancy is not known.

OBJECTIVE

This study aimed to investigate any differences in placental transcriptomic profile between the selectively growth-restricted twins and the normally grown cotwins in monochorionic diamniotic twin pregnancies.

STUDY DESIGN

This was a prospective study of monochorionic diamniotic twin pregnancies complicated by selective fetal growth restriction. Placental biopsy specimens were obtained from the subjects in the delivery suite. The placental transcriptome of the selectively growth-restricted twin was compared with that of the normally grown cotwin. This study was divided into 2 stages: (1) gene discovery phase in which placental tissues from 5 monochorionic diamniotic twin pregnancies complicated by selective fetal growth restriction plus 2 control twin pregnancies underwent transcriptome profiling, and transcriptome profiling was carried out using whole-genome RNA sequencing; and (2) validation phase in which placental tissues from 13 monochorionic diamniotic twin pregnancies with selective fetal growth restriction underwent RNA and protein validation. RNA and protein expression levels of candidate genes were determined using quantitative real-time polymerase chain reaction and immunohistochemistry staining.

RESULTS

A total of 1429 transcripts were differentially expressed in the placentae of selectively growth-restricted twin pairs, where 610 were up-regulated and 819 were down-regulated. Endoplasmic reticulum lectin and mannose 6-phosphate receptor were consistently differentially up-regulated in all placentae of selectively growth-restricted twins. Quantitative real-time polymerase chain reaction and immunohistochemistry staining were used to validate the results (P<.05).

CONCLUSION

The expression of endoplasmic reticulum lectin and mannose 6-phosphate receptor, which are important for angiogenesis and fetal growth, was significantly increased in the placentae of selectively growth-restricted twin of a monochorionic twin pair.

Artificial selection reveals the role of transcriptional constraints in the maintenance of life history variation

The trade-off between reproduction and self-maintenance is a cornerstone of life history theory, yet its proximate underpinnings are elusive. Here, we used an artificial selection approach to create replicated lines of Japanese quail (Coturnix japonica) that differ genetically in their reproductive investment. Whole transcriptome sequencing revealed that females from lines selected for high reproductive output show a consistent upregulation of genes associated with reproduction but a simultaneous downregulation of immune genes. Concordant phenotypic differences in immune function (i.e., specific antibody response against keyhole limpet hemocyanin) were observed between the selection lines, even in males who do not provide parental care. Our findings demonstrate the key role of obligate transcriptional constraints in the maintenance of life history variation. These constraints set fundamental limits to productivity and health in natural and domestic animal populations.

MicroRNA mimics that target the placental renin-angiotensin system inhibit trophoblast proliferation

In early gestation, the human placental renin-angiotensin system (RAS) is upregulated and plays a role in placental development. Among other functions, signalling through the angiotensin II type 1 receptor (AT1R) initiates proliferation. Many microRNAs (miRNAs) targeting placental RAS mRNAs are downregulated at this time. We propose that in early gestation miRNAs that target the placental RAS are downregulated, allowing for the increased RAS expression and proliferation required for adequate placentation. HTR-8/SVneo cells (an immortalized human trophoblast cell line) were used to assess the effect of nine miRNA mimics (at 0.08, 0.16, 0.32 and 0.64 ng/μL) on trophoblast cell proliferation and predicted RAS target mRNAs. The effect of the miRNA mimics on the rate of cell proliferation was assessed using the xCELLigence real-time cell analysis system over 48 h. Levels of miRNAs and predicted RAS target mRNAs were determined by RT-PCR (qPCR, n = 9/group). Statistically different levels of expression were determined (P < 0.05). All nine miRNA mimics significantly affected the proliferation rates of HTR-8/SVneo cells. Five of the miRNA mimics (miR-181a-5p (predicted to target: renin (REN), angiotensin converting enzyme (ACE)), miR-378 (REN, ACE), miR-663 (REN), miR-483-3p (ACE, ACE2, angiotensinogen (AGT), angiotensin II type 1 receptor (AGTR1)) and miR-514 (AGT)) were associated with a dose-dependent reduction in cell proliferation. Seven of the mimics significantly decreased expression of at least one of their predicted target RAS mRNAs. Our study shows that miRNAs targeting placental RAS mRNAs play a role in controlling trophoblast proliferation. As placentation is largely a process of proliferation, changes in expression of these miRNAs may be partly responsible for the expression of the placental RAS, proliferation and placentation.

Angiogenic Transformation in Human Brain Micro Endothelial Cells: Whole Genome DNA Methylation and Transcriptomic Analysis

We tested the hypothesis that endothelial capillary tube formation in 3D cultures in basement membrane extract (BME) is secondary to the altered DNA promoter methylation and mRNA expression in human brain micro endothelial cells (HBMECs). We conducted a whole-genome transcriptomic and methylation microarray and CRISPR/Cas9-mediated gene knockdown to test our hypothesis. The data demonstrated that with angiogenic transformation 1318 and 1490 genes were significantly (p < 0.05) upregulated and downregulated, respectively. We compared our gene expression data with the published databases on GEO and found several genes in common. PTGS2, SELE, ID2, HSPA6, DLX2, HEY2, FOSB, SMAD6, SMAD7, and SMAD9 showed a very high level of expression during capillary tube formation. Among downregulated gene were ITGB4, TNNT1, PRSS35, TXNIP, IGFBP5. The most affected canonical pathways were ATM signaling and cell cycle G2/M DNA damage checkpoint regulation. The top upstream regulators of angiogenic transformation were identified to be VEGF, TP53, HGF, ESR1, and CDKN1A. We compared the changes in gene expression with the change in gene methylation and found hypomethylation of the CpG sites was associated with upregulation of 515 genes and hypermethylation was associated with the downregulation of 31 genes. Furthermore, the silencing of FOSB, FZD7, HEY2, HSPA6, NR4A3, SELE, PTGS2, SMAD6, SMAD7, and SMAD9 significantly inhibited angiogenic transformation as well as cell migration of HBMECs. We conclude that the angiogenic transformation is associated with altered DNA methylation and gene expression changes.

Maternal plasma proteomics in a rat model of pregnancy complications reveals immune and pro-coagulant gene pathway activation

PROBLEM

The Brown Norway (BN) rat is a model of T-helper 2 immune diseases, and also a model of pregnancy disorders that include placental insufficiency, fetal loss, and pre-eclampsia-like symptoms. The aim of this study was to investigate the plasma proteomic/cytokine profile of pregnant BN rats in comparison to that of the Lewis (LEW) rat strain.

METHOD OF STUDY

Plasma proteomics differences were studied at day 13 of pregnancy in pooled plasma samples by differential in-gel electrophoresis, and protein identification was performed by mass spectrometry. Key protein findings and predicted cytokine differences were validated by ELISA using plasma from rats at various pregnancy stages. Proteomics data were used for ingenuity pathway analysis (IPA).

RESULTS

In-gel analysis revealed 74 proteins with differential expression between BN and LEW pregnant dams. ELISA studies confirmed increased maternal plasma levels of complement 4, prothrombin, and C-reactive protein in BN compared to LEW pregnancies. LEW pregnancies showed higher maternal plasma levels of transthyretin and haptoglobin than BN pregnancies. Ingenuity pathway analysis revealed that BN pregnancies are characterized by activation of pro-coagulant, reactive oxygen species, and immune-mediated chronic inflammation pathways, and suggested increased interleukin 6 and decreased transforming growth factor-β1 as potential upstream events. Plasma cytokine analysis revealed that pregnant BN dams have a switch from anti- to pro-inflammatory cytokines with the opposite switch observed in pregnant LEW dams.

CONCLUSION

Brown Norway rats show a maternal pro-inflammatory response to pregnancy that likely contributes to the reproductive outcomes observed in this rat strain.

Blastocyst transfer in mice alters the placental transcriptome and growth

Assisted reproduction technologies (ART) are becoming increasingly common. Therefore, how these procedures influence gene regulation and feto-placental development are important to explore. Here, we assess the effects of blastocyst transfer on mouse placental growth and transcriptome. C57Bl/6 blastocysts were transferred into uteri of B6D2F1 pseudopregnant females and dissected at embryonic day 10.5 for analysis. Compared to non-transferred controls, placentas from transferred conceptuses weighed less even though the embryos were larger on average. This suggested a compensatory increase in placental efficiency. RNA-sequencing of whole male placentas revealed 543 differentially expressed genes (DEGs) after blastocyst transfer: 188 and 355 genes were down-regulated and up-regulated, respectively. DEGs were independently validated in male and female placentas. Bioinformatic analyses revealed that DEGs represented expression in all major placental cell types and included genes that are critical for placenta development and/or function. Furthermore, the direction of transcriptional change in response to blastocyst transfer implied an adaptive response to improve placental function to maintain fetal growth. Our analysis revealed that CpG methylation at regulatory regions of two DEGs was unchanged in female transferred placentas and that DEGs had fewer gene-associated CpG islands (within ~20 kb region) compared to the larger genome. These data suggested that altered methylation at proximal promoter regions might not lead to transcriptional disruption in transferred placentas. Genomic clustering of some DEGs warrants further investigation of long-range, cis-acting epigenetic mechanisms including histone modifications together with DNA methylation. We conclude that embryo transfer, a protocol required for ART, significantly impacts the placental transcriptome and growth.

Role of ACE I/D polymorphism in pathological assessment of preeclampsia in Pakistan

BACKGROUND

Preeclampsia (PE) is a pregnancy-related hypertensive disorder, which may stem from impair placentation. Renin-angiotensin system is one of the mediators of decidualization and trophoblastic proliferation. In the present study women with PE were studied in a comparison of normotensive controls to determine whether Angiotensin-converting enzyme (ACE) gene I/D polymorphism affect the placental villi and umbilical cord formation with the assessment of biochemical and clinical risk factors.

METHODS

Total 400 blood (PE/controls = 200), 400 urine (PE/controls = 200), 90 tissue samples of UC (PE = 50, controls = 40) and 90 placental tissue samples (PE = 50, controls = 40) were recruited. Histomorphological and Histomorphometric analysis were done for placental and umbilical cord tissues. Blood and serum parameters were analyzed, samples were genotyped for I/D polymorphism. Data were statistically analyzed by Independent sample t-test, Chi-square test and the odds ratio.

RESULTS

Histological study revealed significant increase (p < 0.001) in distance from Wharton jelly (in both artery and vein) and outer layer thickness of vein; significant reduction (p < 0.01 and p < 0.05) in the lumen area of artery and vein. Abnormal villi, more syncytial knots (SK) and a significant decrease in elongated and large villi in PE placentas. Analysis of ACE gene determined that genotypic frequencies were statistically significant (p < 0.02) among both groups and DD genotype was predominant in the PE group.

CONCLUSION

Present study reveals that ACE I/D polymorphism might affect the normal placental villi and umbilical cord formation in women with PE. In addition, histological studies and genetic evaluation can provide useful information in the determination of various reasons and mechanisms involved in the pathogenesis of PE in Pakistan.

The role of oxygen in regulating microRNAs in control of the placental renin-angiotensin system

Human placental renin-angiotensin system (RAS) expression is highest in early gestation, at a time when placental oxygen tension is at its lowest (1-3%), and promotes placental development. Some miRNAs predicted to target RAS mRNAs are downregulated in early gestation. We tested the hypothesis that low oxygen suppresses expression of miRNAs that target placental RAS mRNAs, thus increasing concentrations of RAS mRNAs. HTR-8/SVneo cells were cultured in 1, 5 and 20% oxygen for 48 h. Differences in miRNA expression were measured on an Affymetrix miRNA microarray (n = 3/group). Those predicted to target RAS mRNAs, or that were decreased in early gestation, were confirmed by qPCR (n = 9/group). RAS protein levels were assessed by ELISAs or immuno-blotting. Microarray analysis identified four miRNAs predicted to target RAS mRNAs that were differentially expressed between 1 and 5% oxygen. Using qPCR, 15 miRNAs that target the RAS were measured in HTR-8/SVneo cells. Five miRNAs were downregulated in 1% compared with 5% oxygen. Expression of a number of RAS mRNAs (ATP6AP2, AGT, ACE and AGTR1) were increased in either, or both, 1 and 5% oxygen compared with 20% oxygen. AGT protein levels were increased in 1% oxygen compared with 5%. Further validation is needed to confirm that these miRNAs target RAS mRNAs directly and that placental development is partly regulated by oxygen-sensitive miRNAs that target RAS mRNAs. Since placental oxygen tension changes across gestation, changes in expression of these miRNAs may contribute to the transgestational changes in placental RAS expression and the resulting effects on placental development.

Hydrogen-rich water ameliorates rat placental stress induced by water restriction

Dehydration is one of the intrauterine abnormalities that could lead to fetal growth retardation and to increase the risk of a variety of adult diseases later in life. This study were to determine the impact of hydrogen-rich water (HRW) supplementation on placental angiotensin II type 1 receptor and placental oxidative stress induced by water restriction. Pregnant Wistar rat were randomly assigned to one of the three groups (n =12 per group). In control group, pure water and food were supplied ad libitum. Water restriction group and HRW group were respectively given pure water and HRW with free access to food, excepting only one hour was available for drinking from day 7 to day 17 of pregnancy. The placental damages and biomarkers of stress were detected by histopathology, immunohistochemistry and western blot, as well as serological test were performed. We demonstrated that maternal water restriction resulted in reduced urine volume and increased serum osmotic pressure, along with decreased fetus weight and crown-rump length. Although placental weight and the number of fetuses had no significant difference among groups, the placental efficiency significantly increased after the oral administration of HRW to the mothers. Meanwhile, the serological derivatives of reactive oxygen metabolites decreased, a significant improvement of placental microstructure with more developed junctional zone and denser labyrinth was manifested, the upregulated expression of angiotensin II type 1 receptor, nuclear factoκB, malondialdehyde, 8-hydroxydeoxyguanosine, p38, c-Jun N-terminal kinase and down-regulation of superoxide dismutase were revealed in the placenta. Collectively, HRW administration is able to effectively attenuate placental stress induced by water restriction.

Preeclampsia predicts higher incidence of bronchopulmonary dysplasia

INTRODUCTION

It is not known whether very preterm infants born to preeclamptic women have worse outcomes than those delivered preterm for other causes.

OBJECTIVE

We assessed the association between preeclampsia (PE) and the neonatal morbidity and mortality of very preterm infants.

METHODS

Over 2015 and 2016, 11 collaborating Portuguese level III NICUs prospectively enrolled a cohort of mothers with or without PE who delivered liveborn premature infants between 24 and 30 completed weeks of gestation. Data on neonatal morbidities were collected and their association to PE was assessed.

RESULTS

The final cohort consisted of 410 mothers who delivered 494 preterm infants. Infants from PE mothers weighed less than those of non-PE mothers (819 ± 207 g vs. 989 ± 256 g, p < 0.0001). Incidences of respiratory distress syndrome, patent ductus arteriosus, early and nosocomial sepsis, necrotizing enterocolitis, pneumonia, meningitis, retinopathy of prematurity, intraventricular hemorrhage, periventricular infarction, periventricular leukomalacia, and mortality did not differ significantly between infants of PE or non-PE mothers. Incidence of bronchopulmonary dysplasia (BPD-defined as oxygen dependency at 36 weeks) was higher in PE infants compared with non-PE infants by both univariate and multivariate logistic regression (p = 0.007).

CONCLUSION

We conclude that, when controlling for gestational age, maternal PE results in higher incidence of only BPD among preterm Portuguese infants.

A novel rodent model of pregnancy complications associated with genetically determined angiotensin-converting enzyme (ACE) activity

Brown Norway (BN) and Lewis (LW) inbred rat strains harbor different angiotensin-converting enzyme ( Ace) polymorphisms that result in higher ACE activity in BN than LW rats. Thus we hypothesized that pregnant BN rats would show pregnancy complications linked to angiotensin II (AII) activity. We performed longitudinal and cross-sectional studies in pregnant LW and BN rats. We found that BN rats have significantly higher ACE activity and AII levels at prepregnancy and throughout pregnancy compared with LW rats, except at midgestation. BN placentas and maternal kidneys had significantly higher expression of AII receptor 1 (AGTR1) and lower expression of AGTR2 than the respective LW placentas and maternal kidneys. Renin-angiotensin system activation in BN rats correlated with hypertension and proteinuria at gestational days 17-21, which were resolved after delivery. In addition, BN rat pregnancies were characterized by significant fetal loss, restricted growth in surviving fetuses, decreased uteroplacental blood flows, and decreased trophoblast remodeling of uterine arteries compared with LW pregnancies. Short-term losartan treatment significantly increased uteroplacental blood flow and fetal weight and decreased maternal blood pressure (BP) and proteinuria in BN pregnancies. In contrast, losartan treatment significantly decreased uteroplacental blood flow and fetal weight but had no significant effect on maternal BP in LW pregnancies. We conclude that Ace polymorphisms play an important role in the reproductive phenotype of BN and LW rats and that BN rats are a novel model of pregnancy complications in association with genetically controlled, increased ACE activity.

Regulation of the prorenin - angiotensin system by oxygen and miRNAs; parallels between placentation and tumour development?

Tissue renin-angiotensin systems (RASs) are involved in tissue growth and development as they are important regulators of angiogenesis, cell proliferation and migration. The placental RAS is most highly expressed in early gestation, at a time when the oxygen tension within the conceptus is reduced, and plays a key role in placental growth and development. Similar to the placenta, tumour development relies on proliferation, angiogenesis and invasion in order to grow and metastasize. The RAS is known to be upregulated in a variety of solid tumours, including ovarian, endometrial, cervical, breast and prostate. This review explores the roles of oxygen and microRNAs in regulating the normal expression of the placental RAS, providing insight into regulation of its development as well as the development of disease states in which the RAS is overexpressed. We propose that the placental RAS is downregulated by microRNAs that are suppressed during the physiologically normal 'hypoxic' phase of early placentation. Suppression of these miRNAs allows the placental RAS to stimulate placental growth and angiogenesis. We propose that similar mechanisms may be at play in solid tumours, which are characterised by hypoxia.

NADPH oxidase in brain injury and neurodegenerative disorders

Oxidative stress is a common denominator in the pathology of neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis, and multiple sclerosis, as well as in ischemic and traumatic brain injury. The brain is highly vulnerable to oxidative damage due to its high metabolic demand. However, therapies attempting to scavenge free radicals have shown little success. By shifting the focus to inhibit the generation of damaging free radicals, recent studies have identified NADPH oxidase as a major contributor to disease pathology. NADPH oxidase has the primary function to generate free radicals. In particular, there is growing evidence that the isoforms NOX1, NOX2, and NOX4 can be upregulated by a variety of neurodegenerative factors. The majority of recent studies have shown that genetic and pharmacological inhibition of NADPH oxidase enzymes are neuroprotective and able to reduce detrimental aspects of pathology following ischemic and traumatic brain injury, as well as in chronic neurodegenerative disorders. This review aims to summarize evidence supporting the role of NADPH oxidase in the pathology of these neurological disorders, explores pharmacological strategies of targeting this major oxidative stress pathway, and outlines obstacles that need to be overcome for successful translation of these therapies to the clinic.

Placental origins of adverse pregnancy outcomes: potential molecular targets: an Executive Workshop Summary of the Eunice Kennedy Shriver National Institute of Child Health and Human Development

Although much progress is being made in understanding the molecular pathways in the placenta that are involved in the pathophysiology of pregnancy-related disorders, a significant gap exists in the utilization of this information for the development of new drug therapies to improve pregnancy outcome. On March 5-6, 2015, the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health sponsored a 2-day workshop titled Placental Origins of Adverse Pregnancy Outcomes: Potential Molecular Targets to begin to address this gap. Particular emphasis was given to the identification of important molecular pathways that could serve as drug targets and the advantages and disadvantages of targeting these particular pathways. This article is a summary of the proceedings of that workshop. A broad number of topics were covered that ranged from basic placental biology to clinical trials. This included research in the basic biology of placentation, such as trophoblast migration and spiral artery remodeling, and trophoblast sensing and response to infectious and noninfectious agents. Research findings in these areas will be critical for the formulation of the development of future treatments and the development of therapies for the prevention of a number of pregnancy disorders of placental origin that include preeclampsia, fetal growth restriction, and uterine inflammation. Research was also presented that summarized ongoing clinical efforts in the United States and in Europe that has tested novel interventions for preeclampsia and fetal growth restriction, including agents such as oral arginine supplementation, sildenafil, pravastatin, gene therapy with virally delivered vascular endothelial growth factor, and oxygen supplementation therapy. Strategies were also proposed to improve fetal growth by the enhancement of nutrient transport to the fetus by modulation of their placental transporters and the targeting of placental mitochondrial dysfunction and oxidative stress to improve placental health. The roles of microRNAs and placental-derived exosomes, as well as messenger RNAs, were also discussed in the context of their use for diagnostics and as drug targets. The workshop discussed the aspect of safety and pharmacokinetic profiles of potential existing and new therapeutics that will need to be determined, especially in the context of the unique pharmacokinetic properties of pregnancy and the hurdles and pitfalls of the translation of research findings into practice. The workshop also discussed novel methods of drug delivery and targeting during pregnancy with the use of macromolecular carriers, such as nanoparticles and biopolymers, to minimize placental drug transfer and hence fetal drug exposure. In closing, a major theme that developed from the workshop was that the scientific community must change their thinking of the pregnant woman and her fetus as a vulnerable patient population for which drug development should be avoided, but rather be thought of as a deprived population in need of more effective therapeutic interventions.

Genome-Wide Mapping of 5mC and 5hmC Identified Differentially Modified Genomic Regions in Late-Onset Severe Preeclampsia: A Pilot Study

Preeclampsia (PE) is a leading cause of perinatal morbidity and mortality. However, as a common form of PE, the etiology of late-onset PE is elusive. We analyzed 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) levels in the placentas of late-onset severe PE patients (n = 4) and normal controls (n = 4) using a (hydroxy)methylated DNA immunoprecipitation approach combined with deep sequencing ([h]MeDIP-seq), and the results were verified by (h)MeDIP-qPCR. The most significant differentially methylated regions (DMRs) were verified by MassARRAY EppiTYPER in an enlarged sample size (n = 20). Bioinformatics analysis identified 714 peaks of 5mC that were associated with 403 genes and 119 peaks of 5hmC that were associated with 61 genes, thus showing significant differences between the PE patients and the controls (>2-fold, p<0.05). Further, only one gene, PTPRN2, had both 5mC and 5hmC changes in patients. The ErbB signaling pathway was enriched in those 403 genes that had significantly different5mC level between the groups. This genome-wide mapping of 5mC and 5hmC in late-onset severe PE and normal controls demonstrates that both 5mC and 5hmC play epigenetic roles in the regulation of the disease, but work independently. We reveal the genome-wide mapping of DNA methylation and DNA hydroxymethylation in late-onset PE placentas for the first time, and the identified ErbB signaling pathway and the gene PTPRN2 may be relevant to the epigenetic pathogenesis of late-onset PE.

Developmental programming: variations in early growth and adult disease

Suboptimal conditions in utero are associated with the development of adult-onset diseases in offspring. Uteroplacental insufficiency in rats is a well-established animal model used to mimic and study the effects of developmental insults relevant to countries of abundant nutrient supply. However, wide-ranging outcomes for the offspring are apparent between the different investigators that use this model and also between cohorts generated in our laboratory. We aimed to explore the reasons for variability in rat models of uteroplacental insufficiency between different investigators and also between our own animal cohorts. We suggest differences in growth and disease development reflect uniqueness in susceptibility and highlight the complexity of interactions between genetic potential and environmental exposures. The impact of adverse exposures in utero has been described as having far-reaching effects that extend well beyond the first, directly exposed generation. However, the resulting phenotypes are not consistent between generations. This suggests that programmed effects are established de novo in each generation and challenges the prediction of disease. Characterization of growth and disease in the numerous rat models has led to our understanding of the impact of early life experiences on adult health. In order to drive the development of preventative and/or treatment strategies, future studies should focus on identifying the initial cause(s) of uteroplacental insufficiency, including genetic origins and the influence of poor diets.

Placental ischemia induces changes in gene expression in chorionic tissue

Preeclampsia is a serious and common hypertensive complication of pregnancy, affecting ~5 to 8 % of pregnancies. The underlying cause of preeclampsia is believed to be placental ischemia, which causes secretion of pathogenic factors into the maternal circulation. While a number of these factors have been identified, it is likely that others remain to be elucidated. Here, we have utilized a relevant preclinical rodent model of placental ischemia-induced hypertension, the reduced uterine perfusion pressure (RUPP) model, to determine the effect of chronic placental ischemia on the underlying chorionic tissue and placental villi. Tissue from control and RUPP rats were isolated on gestational day 19 and mRNA from these tissues was subjected to microarray analysis to determine differential gene expression. At a statistical cutoff of p < 0.05, some 2,557 genes were differentially regulated between the two groups. Interestingly, only a small subset (22) of these genes exhibited changes of greater than 50 % versus control, a large proportion of which were subsequently confirmed using qRT-PCR analysis. Network analysis indicated a strong effect on inflammatory pathways, including those involving NF-κB and inflammatory cytokines. Of the most differentially expressed genes, the predominant gene classes were extracellular remodeling proteins, pro-inflammatory proteins, and a coordinated upregulation of the prolactin genes. The functional implications of these novel factors are discussed.

Characterization of an animal model of pregnancy-induced vitamin D deficiency due to metabolic gene dysregulation

Vitamin D deficiency has been associated with pregnancy complications such as preeclampsia, gestational diabetes, and recurrent miscarriage. Therefore, we hypothesized differences in vitamin D status between healthy [Sprague-Dawley (SD) and Lewis (LW)] and complicated [Brown Norway (BN)] rat pregnancies. In SD, LW, and BN rats, we analyzed the maternal plasma levels of the vitamin D metabolites 25-OH-D and 1,25-(OH)2-D at prepregnancy, pregnancy, and postpartum. Analysis of the active metabolite 1,25-(OH)2-D showed a twofold increase in pregnant SD and LW rats but a nearly 10-fold decrease in pregnant BN rats compared with nonpregnant controls. BN rats had a pregnancy-dependent upregulation of CYP24a1 expression, a key enzyme that inactivates vitamin D metabolites. In contrast, the maternal renal expression of CYP24a1 in SD and LW rats remained constant throughout pregnancy. Analysis of the vitamin D receptor (VDR) indicated that LW and SD but not BN rats experience a pregnancy-induced 10-fold decrease in maternal renal VDR protein levels. Further analysis of bisulfite-converted and genomic DNA indicated that the observed differences in maternal renal regulation of CYP24a1 during pregnancy and lactation are not due to differences in CYP24a1 promoter methylation or single-nucleotide polymorphisms. Finally, supplementation with 1,25-(OH)2-D significantly improved the reproductive phenotype of BN rats by increasing litter size and maternal-fetal weight outcomes. We conclude that BN rats represent a novel animal model of pregnancy-specific vitamin D deficiency that is linked to pregnancy complications. Vitamin D deficiency in BN rats correlates with maternal renal CYP24a1 upregulation followed by CYP27b1 upregulation.

The peripheral whole-blood transcriptome of acute pyelonephritis in human pregnancya

OBJECTIVE

Human pregnancy is characterized by activation of the innate immune response and suppression of adaptive immunity. The former is thought to provide protection against infection for the mother, and the latter, tolerance against paternal antigens expressed in fetal cells. Acute pyelonephritis is associated with an increased risk of acute respiratory distress syndrome and sepsis in pregnant (vs. nonpregnant) women. The objective of this study was to describe the gene expression profile (transcriptome) of maternal whole blood in acute pyelonephritis.

METHOD

A case-control study was conducted to include pregnant women with acute pyelonephritis (n=15) and women with a normal pregnancy (n=34). Affymetrix HG-U133 Plus 2.0 arrays (Affymetrix, Santa Clara, CA, USA) were used for gene expression profiling. A linear model was used to test the association between the presence of pyelonephritis and gene expression levels while controlling for white blood cell count and gestational age. A fold change of 1.5 was considered significant at a false discovery rate of 0.1. A subset of differentially expressed genes (n=56) was tested with real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) (cases, n=19; controls, n=59). Gene ontology and pathway analyses were applied.

RESULTS

A total of 983 genes were differentially expressed in acute pyelonephritis: 457 were upregulated and 526 were downregulated. Significant enrichment of 300 biological processes and 63 molecular functions was found in pyelonephritis. Significantly impacted pathways in pyelonephritis included (a) cytokine-cytokine receptor interaction, (b) T-cell receptor signaling, (c) Jak-STAT signaling, and (d) complement and coagulation cascades. Of 56 genes tested by qRT-PCR, 48 (85.7%) had confirmation of differential expression.

CONCLUSION

This is the first study of the transcriptomic signature of whole blood in pregnant women with acute pyelonephritis. Acute infection during pregnancy is associated with the increased expression of genes involved in innate immunity and the decreased expression of genes involved in lymphocyte function.

The effect of gestational age on angiogenic gene expression in the rat placenta

The placenta plays a central role in determining the outcome of pregnancy. It undergoes changes during gestation as the fetus develops and as demands for energy substrate transfer and gas exchange increase. The molecular mechanisms that coordinate these changes have yet to be fully elucidated. The study performed a large scale screen of the transcriptome of the rat placenta throughout mid-late gestation (E14.25–E20) with emphasis on characterizing gestational age associated changes in the expression of genes invoved in angiogenic pathways. Sprague Dawley dams were sacrificed at E14.25, E15.25, E17.25 and E20 (n = 6 per group) and RNA was isolated from one placenta per dam. Changes in placental gene expression were identifed using Illumina Rat Ref-12 Expression BeadChip Microarrays. Differentially expressed genes (>2-fold change, <1% false discovery rate, FDR) were functionally categorised by gene ontology pathway analysis. A subset of differentially expressed genes identified by microarrays were confirmed using Real-Time qPCR. The expression of thirty one genes involved in the angiogenic pathway was shown to change over time, using microarray analysis (22 genes displayed increased and 9 gene decreased expression). Five genes (4 up regulated: Cd36, Mmp14, Rhob and Angpt4 and 1 down regulated: Foxm1) involved in angiogenesis and blood vessel morphogenesis were subjected to further validation. qPCR confirmed late gestational increased expression of Cd36, Mmp14, Rhob and Angpt4 and a decrease in expression of Foxm1 before labour onset (P<0.0001). The observed acute, pre-labour changes in the expression of the 31 genes during gestation warrant further investigation to elucidate their role in pregnancy.

Differences and similarities in the transcriptional profile of peripheral whole blood in early and late-onset preeclampsia: insights into the molecular basis of the phenotype of preeclampsiaa

OBJECTIVE

Preeclampsia (PE) can be sub-divided into early- and late-onset phenotypes. The pathogenesis of these two phenotypes has not been elucidated. To gain insight into the mechanisms of disease, the transcriptional profiles of whole blood from women with early- and late-onset PE were examined.

METHODS

A cross-sectional study was conducted to include women with: i) early-onset PE (diagnosed prior to 34 weeks, n=25); ii) late-onset PE (after 34 weeks, n=47); and iii) uncomplicated pregnancy (n=61). Microarray analysis of mRNA expression in peripheral whole blood was undertaken using Affymetrix microarrays. Differential gene expression was evaluated using a moderated t-test (false discovery rate <0.1 and fold change >1.5), adjusting for maternal white blood cell count and gestational age. Validation by real-time qRT-PCR was performed in a larger sample size [early PE (n=31), late PE (n=72) and controls (n=99)] in all differentially expressed genes. Gene ontology analysis and pathway analysis were performed.

RESULTS

i) 43 and 28 genes were differentially expressed in early- and late-onset PE compared to the control group, respectively; ii) qRT-PCR confirmed the microarray results for early and late-onset PE in 77% (33/43) and 71% (20/28) of genes, respectively; iii) 20 genes that are involved in coagulation (SERPINI2), immune regulation (VSIG4, CD24), developmental process (H19) and inflammation (S100A10) were differentially expressed in early-onset PE alone. In contrast, only seven genes that encoded proteins involved in innate immunity (LTF, ELANE) and cell-to-cell recognition in the nervous system (CNTNAP3) were differentially expressed in late-onset PE alone. Thirteen genes that encode proteins involved in host defense (DEFA4, BPI, CTSG, LCN2), tight junctions in blood-brain barrier (EMP1) and liver regeneration (ECT2) were differentially expressed in both early- and late-onset PE.

CONCLUSION

Early- and late-onset PE are characterized by a common signature in the transcriptional profile of whole blood. A small set of genes were differentially regulated in early- and late-onset PE. Future studies of the biological function, expression timetable and protein expression of these genes may provide insight into the pathophysiology of PE.

Gene expression in sheep carotid arteries: major changes with maturational development

BACKGROUND

With development from immature fetus to near-term fetus, newborn, and adult, the cerebral vasculature undergoes a number of fundamental changes. Although the near-term fetus is prepared for a transition from an intra- to extra-uterine existence, this is not necessarily the case with the premature fetus, which is more susceptible to cerebrovascular dysregulation. In this study, we tested the hypothesis that the profound developmental and age-related differences in cerebral blood flow are associated with significant underlying changes in gene expression.

METHODS

With the use of oligonucleotide microarray and pathway analysis, we elucidated significant changes in the transcriptome with development in sheep carotid arteries.

RESULTS

As compared with adult, we demonstrate a U-shaped relationship of gene expression in major cerebrovascular network/pathways during early life, e.g., the level of gene expression in the premature fetus and newborn is considerably greater than that of the near-term fetus. Specifically, cell proliferation, growth, and assembly pathway genes were upregulated during early life. In turn, as compared with adult, mitogen-activated protein kinase-extracellular regulated kinase, actin cytoskeleton, and integrin-signaling pathways were downregulated during early life.

CONCLUSION

In cranial vascular smooth muscle, highly significant changes occur in important cellular and signaling pathways with maturational development.

Maternal protein restriction reduces expression of angiotensin I-converting enzyme 2 in rat placental labyrinth zone in late pregnancy

Both the systemic and the uteroplacental renin-angiotensin system (RAS) display dramatic changes during pregnancy. However, whether gestational protein insufficiency affects the expressions of RAS in the placenta remains unknown. In this study, we hypothesized that the expression of Ace2 in the placental labyrinth was reduced by maternal protein restriction. Pregnant Sprague-Dawley rats were fed a normal diet or a low-protein diet (LP) from Day 1 of pregnancy until they were killed at Day 14 or Day 18. The labyrinth zone (LZ) of the placenta was then dissected and snap frozen for expression analysis by quantitative real-time PCR of Ace, Ace2, Agtr1a, Agtr1b, and Agtr2. Formalin-fixed placentas were used for immunohistochemical analysis on ACE and ACE2 proteins. The findings include 1) the expression of Ace2 in rat LZ was reduced by maternal protein restriction in late pregnancy; 2) ACE protein was mainly present in syncytiotrophoblasts, whereas ACE2 protein was found predominantly in fetal mesenchymal tissue and fetal capillaries; 3) Agtr1a was predominant in the rat LZ, and its mRNA levels, but not protein levels, were reduced by LP; 4) expressions of Ace, Ace2, and Agtr1a in the rat LZ and their response to LP occurred in a gender-dependent manner. These results may indicate that a reduced expression of Ace2 and perhaps an associated reduction in angiotensin (1-7) production in the placenta by maternal protein restriction may be responsible for fetal growth restriction and associated programming of adulthood hypertension.

Rat placentation: an experimental model for investigating the hemochorial maternal-fetal interface

The rat possesses hemochorial placentation with deep intrauterine trophoblast cell invasion and trophoblast-directed uterine spiral artery remodeling; features shared with human placentation. Recognition of these similarities spurred the establishment of in vitro and in vivo research methods using the rat as an animal model to address mechanistic questions regarding development of the hemochorial placenta. The purpose of this review is to provide the requisite background to help move the rat to the forefront in placentation research.

A role for Notch signaling in trophoblast endovascular invasion and in the pathogenesis of pre-eclampsia

Placental trophoblasts (TBs) invade and remodel uterine vessels with an arterial bias. This process, which involves vascular mimicry, re-routes maternal blood to the placenta, but fails in pre-eclampsia. We investigated Notch family members in both contexts, as they play important roles in arterial differentiation/function. Immunoanalyses of tissue sections showed step-wise modulation of Notch receptors/ligands during human TB invasion. Inhibition of Notch signaling reduced invasion of cultured human TBs and expression of the arterial marker EFNB2. In mouse placentas, Notch activity was highest in endovascular TBs. Conditional deletion of Notch2, the only receptor upregulated during mouse TB invasion, reduced arterial invasion, the size of maternal blood canals by 30-40% and placental perfusion by 23%. By E11.5, there was litter-wide lethality in proportion to the number of mutant offspring. In pre-eclampsia, expression of the Notch ligand JAG1 was absent in perivascular and endovascular TBs. We conclude that Notch signaling is crucial for TB vascular invasion.

Chromosome-substituted rat strains provide insights into the genetics of placentation

The rat possesses a hemochorial form of placentation. Pronounced intrauterine trophoblast cell invasion and vascular remodeling characterize this type of placentation. Strain-specific patterns of placentation are evident in the rat. Some rat strains exhibit deep intrauterine trophoblast invasion and an expanded junctional zone [Holtzman Sprague-Dawley (HSD), Dahl salt sensitive (DSS)], whereas placentation sites of other rat strains are characterized by shallow invasion and a restricted junctional zone [Brown Norway (BN)]. In this report, we identified a quantitative trait that was used to distinguish strain-specific features of rat placentation. Junctional zone prolactin family 5, subfamily a, member 1 (Prl5a1) transcript levels were significantly greater in BN rats than in HSD or DSS rats. Prl5a1 transcript levels were used as a quantitative trait to screen placentation sites from chromosome-substituted rat strains (BN chromosomes introgressed into the DSS inbred strain; DSS-BN panel). Litter size, placental weights, and fetal weights were not significantly different among the chromosome-substituted strains. Regulation of the junctional zone Prl5a1 transcript-level quantitative trait was multifactoral. Chromosome-substituted strains possessing BN chromosomes 14 or 17 introgressed into the DSS inbred rat strain displayed Prl5a1 transcript levels that were significantly different from the DSS pattern and more closely resembled the BN pattern. The in situ placental distribution of Prl5a1 mRNA and the structure of the junctional zone of DSS-BN17 rats mimicked that observed for the BN rat. Prl5a1 gene expression was also assessed in BN vs. HSD trophoblast stem cells and following reciprocal BN and HSD embryo transfer. Strain differences intrinsic to trophoblast and maternal environment were identified. In summary, we have identified chromosomes 14 and 17 as possessing regulatory information controlling a quantitative trait associated with rat placentation.

Role of axonal guidance factor netrin-1 in human placental vascular growth

This study investigated the role of netrin-1 in placental vascular development. In vitro rat aortic ring assay and in vivo Matrigel plug assay were conducted to exmaine the effect of netrin-1 on angiogenesis. Human placental microvascular endothelial cells (HPMECs) were isolated and cultured and their viability, migration and tubular formation were studied, in order to examine the effects of netrin-1. The results showed that netrin-1 potently stimulated neovascularization in a mouse Matrigel plug in vivo and the sprouting of endothelial cells in rat aortic rings in vitro. In addition, netrin-1 enhanced the viability, migration and tube formation of HPMECs. Our study suggested that netrin-1 could significantly promote the formation of blood vessels of human placenta and may be a potential target for developing new therapeutic strategies for placental vasculature-related diseases.

Inflammatory pattern recognition receptors and their ligands: factors contributing to the pathogenesis of preeclampsia

Problem

Preeclampsia, a pregnancy-specific hypertensive syndrome, is one of the leading causes of premature births as well as fetal and maternal death. Preeclampsia lacks effective therapies because of the poor understanding of disease pathogenesis. The aim of this paper is to review molecular signaling pathways that could be responsible for the pathogenesis of preeclampsia.

Method of study

This article reviews the English-language literature for pathogenesis and pathophysiological mechanisms of preeclampsia based on genome-wide gene expression profiling and proteomic studies.

Results

We show that the expression of the genes and proteins involved in response to stress, host-pathogen interactions, immune system, inflammation, lipid metabolism, carbohydrate metabolism, growth and tissue remodeling was increased in preeclampsia. Several significant common pathways observed in preeclampsia overlap the datasets identified in TLR (Toll-like receptor)- and RAGE (receptor for advanced glycation end products)-dependent signaling pathways. Placental oxidative stress and subsequent chronic inflammation are considered to be major contributors to the development of preeclampsia.

Conclusion

This review summarizes recent advances in TLR- and RAGE-mediated signaling and the target molecules, and provides new insights into the pathogenesis of preeclampsia.

Antenatal maternal hypoxic stress: adaptations of the placental renin-angiotensin system in the mouse

The stress of Antenatal Maternal Hypoxia (AMH) can lead to a number of physiological and pathological changes in both mother and fetus, changes which can be linked to alterations in placental morphology and gene regulation. Recently, in the Brown Norway rat "model" of placental insufficiency, we reported alterations in placental renin-angiotensin system (RAS) genes. Moreover, AMH can lead to reduced oxygen availability to the fetus, similar to a state of placental insufficiency. Thus, in pregnant mice dams we tested the hypothesis that antenatal maternal hypoxic stress leads to alterations in the placental RAS. These alterations may, in part, account for the phenotypic changes in both pregnant mice dams as well as fetus and adult offspring.

METHODS

Pregnant FVB/NJ mice dams were either maintained as controls, or exposed to 10.5% O(2) for 48 h from 15.5 to 17.5 day post coitum. We then measured placental mRNA and protein expression of several RAS genes (n = 4 to 5; P < 0.05 was considered significant).

RESULT

In murine placenta: (1) angiotensinogen (AGT) mRNA was undetectable; however, AGT protein was detectable and increased significantly with AMH. (2) In AMH, although renin mRNA was reduced protein expression increased, in association with decreased microRNA (miRNA) 199b, which can lead to increased renin translation. (3) Also in AMH placenta, angiotensin converting enzyme (ACE) -1 mRNA was unaltered; however, protein expression increased significantly, in association with decreased miRNA 27a, which can result in increased ACE-1 translation. (4) In AMH placenta, ACE-2 mRNA was reduced significantly, whereas protein expression was significantly greater, in association with reduced miRNA 429. (5) In AMH placenta, angiotensin II type (AT) -1a receptor mRNA expression was unaltered while AT-1b receptor mRNA was undetectable in both groups. Moreover, AT-1 receptor protein expression was unchanged in response to AMH. (6) AT-2 receptor mRNA and proteins were undetectable in both groups.

CONCLUSION

The normal murine placenta possesses several components of RAS, and in response to AMH several of these elements undergo important changes. In addition, differential expression of RAS mRNA, miRNA and protein, indicate post-transcriptional regulatory mechanisms involved with hypoxic stress, and necessitate further investigation.

Antenatal maternal hypoxic stress: adaptations in fetal lung Renin-Angiotensin system

Antenatal maternal hypoxia (AMH) can lead to intrauterine growth restriction (IUGR), as well as idiopathic pulmonary hypertension of newborn and adult, the latter of which may be a consequence of alterations in the local pulmonary renin-angiotensin system (RAS). Little is known of these adaptations, however. Thus, we tested the hypothesis that antenatal maternal hypoxia is associated with alterations in gene and protein expression of the pulmonary renin-angiotensin system, which may play an important role in pulmonary disorders in the offspring. In FVB/NJ mice, we studied messenger RNA (mRNA) and protein expression, as well as promoter DNA methylation and microRNA (miRNA) levels in response to 48 hours hypoxia (10.5% O(2)) at 15.5 day post coitum (DPC). In response to AMH, the pulmonary mRNA levels of angiotensin-converting enzyme (ACE) 1.2, ACE-2, and angiotensin II type 1b (AT-1b) receptors were increased significantly, as compared to controls (N = 4). In response to antenatal hypoxia, pulmonary protein levels of renin and ACE-2 also were increased significantly, whereas ACE-1 protein expression was reduced. In fetal lungs, we also observed reduced expression of the miRNAs: mmu-mir -199b, -27b, -200b, and -468 that putatively increase the translation of renin, ACE-1, ACE-2, and AT-1 receptors, respectively. In response to AMH, promoter methylation of ACE was unchanged. We conclude that AMH leads to changes in expression of pulmonary RAS of fetal mice. The possible implications of these changes for the regulation of pulmonary vascular contractility in later life remain to be explored.