Author Correction: Human placenta has no microbiome but can contain potential pathogens.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Human placenta has no microbiome but can contain potential pathogens.

We sought to determine whether pre-eclampsia, spontaneous preterm birth or the delivery of infants who are small for gestational age were associated with the presence of bacterial DNA in the human placenta. Here we show that there was no evidence for the presence of bacteria in the large majority of placental samples, from both complicated and uncomplicated pregnancies. Almost all signals were related either to the acquisition of bacteria during labour and delivery, or to contamination of laboratory reagents with bacterial DNA. The exception was Streptococcus agalactiae (group B Streptococcus), for which non-contaminant signals were detected in approximately 5% of samples collected before the onset of labour. We conclude that bacterial infection of the placenta is not a common cause of adverse pregnancy outcome and that the human placenta does not have a microbiome, but it does represent a potential site of perinatal acquisition of S. agalactiae, a major cause of neonatal sepsis.

Biomarkers associated with cardiovascular disease in women with spontaneous preterm birth: A case-control study.

INTRODUCTION: Women with spontaneous preterm birth have an increased risk of cardiovascular disease later in life. Studies suggest potential pathophysiological mechanisms in common, but whether these could be identified by measurement of soluble circulating protein biomarkers in women with spontaneous preterm birth is unknown. The aim of this study was to determine if protein biomarkers associated with cardiovascular disease distinguish women with spontaneous preterm birth from healthy controls, both at pregnancy and at follow up. MATERIAL AND METHODS: Study participants were identified in the population-based Uppsala biobank of pregnant women in Sweden, where plasma samples were collected in mid-pregnancy. In a first screening phase, we identified participants who subsequently experienced spontaneous preterm birth (<37 weeks) in the index pregnancy (N = 13) and controls (N = 6). In these samples, differences in protein expression were examined by comparative mass spectrometry. In a second validation phase, we invited 100 cases with previous spontaneous preterm birth in the index pregnancy and 100 controls (matched for age, body mass index, and year of delivery) from the same source population, to a follow-up visit 4-15 years after pregnancy. At follow up, we collected plasma samples and data on cardiovascular risk factors. We measured concentrations of selected biomarkers identified in the screening phase, as well as lipid profiles in samples both from pregnancy (biobank) and follow up. CLINICALTRIALS: gov registration NCT05693285. RESULTS: In the screening phase, fibrinogen, cadherin-5, complement C5, factor XII, plasma kallikrein, apolipoprotein M, and vitamin D-binding protein differed significantly at pregnancy. In the validation phase, 65 women agreed to participate (35 cases and 30 controls), with a median follow-up time of 11.8 years since pregnancy. The concentration of fibrinogen (p = 0.02) and triglycerides (p = 0.03) were slightly higher in cases compared with matched controls at follow up. CONCLUSIONS: Compared with women without preterm birth, those with spontaneous preterm birth had slightly higher concentrations of fibrinogen, both at mid-pregnancy and a decade after pregnancy. Additionally, we found slightly higher concentration of triglycerides at follow up in women with previous spontaneous preterm birth. The relevance of this finding is uncertain but might indicate potential pathophysiological mechanisms in common between spontaneous preterm birth and cardiovascular disease.

Evolutionary History of Endogenous Human Herpesvirus 6 Reflects Human Migration out of Africa.

Human herpesvirus 6A and 6B (HHV-6) can integrate into the germline, and as a result, ∼70 million people harbor the genome of one of these viruses in every cell of their body. Until now, it has been largely unknown if 1) these integrations are ancient, 2) if they still occur, and 3) whether circulating virus strains differ from integrated ones. Here, we used next-generation sequencing and mining of public human genome data sets to generate the largest and most diverse collection of circulating and integrated HHV-6 genomes studied to date. In genomes of geographically dispersed, only distantly related people, we identified clades of integrated viruses that originated from a single ancestral event, confirming this with fluorescent in situ hybridization to directly observe the integration locus. In contrast to HHV-6B, circulating and integrated HHV-6A sequences form distinct clades, arguing against ongoing integration of circulating HHV-6A or "reactivation" of integrated HHV-6A. Taken together, our study provides the first comprehensive picture of the evolution of HHV-6, and reveals that integration of heritable HHV-6 has occurred since the time of, if not before, human migrations out of Africa.

Alcohol exposure prior to pregnancy-does hazardous consumption affect placenta- and inflammatory-mediated pregnancy outcomes? A Swedish population-based cohort study.

INTRODUCTION: Alcohol consumption during pregnancy is related to severe birth complications such as low birthweight, preterm birth and birth defects. During the last decade, the Alcohol Use Disorders Identification Test (AUDIT) has been used as a screening tool in Swedish maternal healthcare units to identify hazardous, pre-pregnancy alcohol use. However, evaluation of the screening with AUDIT, as well as adverse maternal or neonatal outcomes, has not been assessed at a national level. MATERIAL AND METHODS: This was a population-based cohort study of 530 458 births from 2013 to 2018 using demographic, reproductive and maternal health data from the Swedish Pregnancy Register. Self-reported alcohol consumption in the year before pregnancy, measured as AUDIT scores, was categorized into moderate (6-13 points) and high-risk (14-40 points) consumption, with low-risk (0-5 points) consumption as the reference group. Associations with pregnancy- and birth outcomes were explored with logistic regressions using generalized estimating equation models, adjusting for maternal and socioeconomic characteristics. Estimates are presented as adjusted odds ratios (aORs) with 95% confidence intervals (CIs). RESULTS: High-risk and moderate pre-pregnancy alcohol consumption was associated with preeclampsia, preterm birth and birth of an infant small for gestational age (SGA), but these associations were nonsignificant after adjustments. Prior moderate-risk (aOR 1.29, 95% CI 1.17-1.42) and high-risk consumption (aOR 1.62, 95% CI 1.17-2.25) increased the likelihood of intrapartum and neonatal infections. CONCLUSIONS: Apart from identifying hazardous alcohol consumption prior to pregnancy and the offer of counseling, screening with the AUDIT in early pregnancy indicates a high risk of inflammatory-/placenta-mediated pregnancy and birth outcomes. For most outcomes, AUDIT was not an independent contributor when adjusting for confounding factors. Hazardous alcohol use prior to pregnancy was independently linked to intrapartum and neonatal infections; conditions associated with morbidity and long-term sequalae. These associations may be explained by alcohol-induced changes in the maternal or fetal immune system in early pregnancy or persistent alcohol intake during pregnancy, or may depend on unidentified confounding factors.

Alcohol consumption habits and associations with anxiety or depressive symptoms postpartum in women with high socioeconomic status in Sweden.

Postpar tum depression and anxiety are common among new mothers. It is well-established that in the general population alcohol use is associated with depression and anxiety. Linking alcohol consumption to symptoms of postpartum depression (PPDS) or postpartum anxiety (PPAS) is presently less established. This study aims to determine if alcohol consumption pre-pregnancy, 6 weeks postpartum, 6 months postpartum, or changes in alcohol consumption are associated with PPDS or PPAS. Longitudinal data on 3849 women from a Swedish perinatal cohort were analyzed using logistic regression analyses for associations between alcohol consumption and symptoms of anxiety or depression, as assessed with the Edinburgh Postnatal Depression Scale. There was no association between pre-pregnancy drinking habits and PPDS (p = 0.588, n = 2479) or PPAS (p = 0.942; n = 2449) at 6 weeks postpartum. Similarly, no associations were observed between concurrent drinking habits at 6 weeks postpartum and PPAS (p = 0.070, n = 3626), 6 months postpartum and PPDS (0.647, n = 3461) or PPAS (p = 0.700, n = 3431). However, there was an association between drinking habits at 6 weeks postpartum and concurrent PPDS (p = 0.047, n = 3659). In conclusion, robust associations were not found between postpartum alcohol consumption and mood symptoms. This lack of association between poor mental health and risk behaviors in new mothers could be interpreted as a result of long-term policy work and high participation in Swedish maternity care. Future studies need to address these research questions in more diverse socio-cultural contexts.

Abnormal placental CD8+ T-cell infiltration is a feature of fetal growth restriction and pre-eclampsia.

KEY POINTS: Placental pathological abnormalities are more frequently observed in complicated pregnancies than in healthy pregnancies. Infiltration of CD8+ T-cells into the placental villous tissue occurred in both fetal growth restriction and pre-eclampsia, whereas CD79α+ B-cell infiltration was only apparent with reduced fetal growth. Vascularization, fibrin depositions, macrophage and neutrophil infiltration in the placenta did not differ between healthy and complicated pregnancies. ABSTRACT: Fetal growth restriction (FGR) and pre-eclampsia are severe, adverse pregnancy outcomes. Alterations in placental histology are frequently reported in these pregnancy complications and are often based upon scoring by pathologists. However, many alterations are also observed in placenta from uncomplicated pregnancies. Moreover, knowledge of disease state may bias assessment. We sought to perform an objective comparison of placental microscopic appearance in normal and complicated pregnancies. Placental villous tissue (n = 823) and edge biopsies (n = 488) from 871 individual, singleton pregnancies were collected after delivery. Cases of small-for-gestational age (SGA) or pre-eclampsia were matched with healthy controls. A subset of the SGA cases displayed signs of FGR. Cases of preterm delivery were also included. Tissue sections were stained with haematoxylin and eosin or antibodies for CD8, CD14, CD31, CD79α and elastase. Images were scored by two experienced pathologists for pathological features or analysed by image analysis and stereology. Analyses were performed blind to case-control status and gestational age. Volume fraction of T-cells increased in placentas from pregnancies complicated by pre-eclampsia (adjusted odds ratio (aOR) 1.46, 95% CI: 1.12-1.90) and FGR (aOR 1.64, 95% CI: 1.11-2.43), whereas B-cells only increased in FGR (aOR 1.65, 95% CI: 1.05-2.60). Pathological abnormalities in villous tissue were reported in 21.4% (88/411) of complicated pregnancies and 14.3% (52/363) of controls (OR 1.62, 95% CI: 1.12-2.37). There were no differences in the fractions of endothelial cells, fibrin deposition, macrophages and neutrophils when comparing normal and complicated pregnancies. In conclusion, FGR and pre-eclampsia are associated with T-cell infiltration of the placenta and placental pathological abnormalities.

Hyperandrogenism and insulin resistance-induced fetal loss: evidence for placental mitochondrial abnormalities and elevated reactive oxygen species production in pregnant rats that mimic the clinical features of polycystic ovary syndrome.

KEY POINTS: Women with polycystic ovary syndrome (PCOS) commonly suffer from miscarriage, but the underlying mechanisms remain unknown. Herein, pregnant rats chronically treated with 5α-dihydrotestosterone (DHT) and insulin exhibited hyperandrogenism and insulin resistance, as well as increased fetal loss, and these features are strikingly similar to those observed in pregnant PCOS patients. Fetal loss in our DHT+insulin-treated pregnant rats was associated with mitochondrial dysfunction, disturbed superoxide dismutase 1 and Keap1/Nrf2 antioxidant responses, over-production of reactive oxygen species (ROS) and impaired formation of the placenta. Chronic treatment of pregnant rats with DHT or insulin alone indicated that DHT triggered many of the molecular pathways leading to placental abnormalities and fetal loss, whereas insulin often exerted distinct effects on placental gene expression compared to co-treatment with DHT and insulin. Treatment of DHT+insulin-treated pregnant rats with the antioxidant N-acetylcysteine improved fetal survival but was deleterious in normal pregnant rats. Our results provide insight into the fetal loss associated with hyperandrogenism and insulin resistance in women and suggest that physiological levels of ROS are required for normal placental formation and fetal survival during pregnancy. ABSTRACT: Women with polycystic ovary syndrome (PCOS) commonly suffer from miscarriage, but the underlying mechanism of PCOS-induced fetal loss during pregnancy remains obscure and specific therapies are lacking. We used pregnant rats treated with 5α-dihydrotestosterone (DHT) and insulin to investigate the impact of hyperandrogenism and insulin resistance on fetal survival and to determine the molecular link between PCOS conditions and placental dysfunction during pregnancy. Our study shows that pregnant rats chronically treated with a combination of DHT and insulin exhibited endocrine aberrations such as hyperandrogenism and insulin resistance that are strikingly similar to those in pregnant PCOS patients. Of pathophysiological significance, DHT+insulin-treated pregnant rats had greater fetal loss and subsequently decreased litter sizes compared to normal pregnant rats. This negative effect was accompanied by impaired trophoblast differentiation, increased glycogen accumulation, and decreased angiogenesis in the placenta. Mechanistically, we report that over-production of reactive oxygen species (ROS) in the placenta, mitochondrial dysfunction, and disturbed superoxide dismutase 1 (SOD1) and Keap1/Nrf2 antioxidant responses constitute important contributors to fetal loss in DHT+insulin-treated pregnant rats. Many of the molecular pathways leading to placental abnormalities and fetal loss in DHT+insulin treatment were also seen in pregnant rats treated with DHT alone, whereas pregnant rats treated with insulin alone often exerted distinct effects on placental gene expression compared to insulin treatment in combination with DHT. We also found that treatment with the antioxidant N-acetylcysteine (NAC) improved fetal survival in DHT+insulin-treated pregnant rats, an effect related to changes in Keap1/Nrf2 and nuclear factor-κB signalling. However, NAC administration resulted in fetal loss in normal pregnant rats, most likely due to PCOS-like endocrine abnormality induced by the treatment. Our results suggest that the deleterious effects of hyperandrogenism and insulin resistance on fetal survival are related to a constellation of mitochondria-ROS-SOD1/Nrf2 changes in the placenta. Our findings also suggest that physiological levels of ROS are required for normal placental formation and fetal survival during pregnancy.

The effect of antenatal depression and antidepressant treatment on placental tissue: a protein-validated gene expression study.

BACKGROUND: Antenatal depression affects 10-20% of pregnant women. Around 2-4% of European pregnant women use antidepressant treatment, most commonly selective serotonin reuptake inhibitors (SSRIs). Poor pregnancy outcomes, such as preterm birth and low birth weight, have been described in women with antenatal depression and in pregnant women on SSRI treatment. However, the effects of antenatal depression and antidepressant treatment on the placenta are largely unknown. The aim of this work was to compare placental gene and protein expression in healthy women, women with untreated antenatal depression and women on antidepressant treatment during pregnancy. METHODS: Placental samples from 47 controls, 25 depressed and 45 SSRI-treated women were analysed by means of qPCR using custom-designed TaqMan low-density arrays (TLDAs) for 44 genes previously known to be involved in the pathophysiology of depression, and expressed in the placenta. Moreover, placental protein expression was determined by means of immunohistochemistry in 37 healthy controls, 13 women with untreated depression and 21 women on antidepressant treatment. Statistical comparisons between groups were performed by one-way ANOVA or the Kruskal-Wallis test. RESULTS: Nominally significant findings were noted for HTR1A and NPY2R, where women with untreated depression displayed higher gene expression than healthy controls (p < 0.05), whereas women on antidepressant treatment had similar expression as healthy controls. The protein expression analyses revealed higher expression of HTR1A in placentas from women on antidepressant treatment, than in placentas from healthy controls (p < 0.05). CONCLUSION: The differentially expressed HTR1A, both at the gene and the protein level that was revealed in this study, suggests the involvement of HTR1A in the effect of antenatal depression on biological mechanisms in the placenta. More research is needed to elucidate the role of depression and antidepressant treatment on the placenta, and, further, the effect on the fetus.

Expression and functional characterisation of System L amino acid transporters in the human term placenta.

BACKGROUND: System L transporters LAT1 (SLC7A5) and LAT2 (SLC7A8) mediate the uptake of large, neutral amino acids in the human placenta. Many System L substrates are essential amino acids, thus representing crucial nutrients for the growing fetus. Both LAT isoforms are expressed in the human placenta, but the relative contribution of LAT1 and LAT2 to placental System L transport and their subcellular localisation are not well established. Moreover, the influence of maternal body mass index (BMI) on placental System L amino acid transport is poorly understood. Therefore the aims of this study were to determine: i) the relative contribution of the LAT isoforms to System L transport activity in primary human trophoblast (PHT) cells isolated from term placenta; ii) the subcellular localisation of LAT transporters in human placenta; and iii) placental expression and activity of System L transporters in response to maternal overweight/obesity. METHODS: System L mediated leucine uptake was measured in PHT cells after treatment with si-RNA targeting LAT1 and/or LAT2. The localisation of LAT isoforms was studied in isolated microvillous plasma membranes (MVM) and basal membranes (BM) by Western blot analysis. Results were confirmed by immunohistochemistry in sections of human term placenta. Expression and activity System L transporters was measured in isolated MVM from women with varying pre-pregnancy BMI. RESULTS: Both LAT1 and LAT2 isoforms contribute to System L transport activity in primary trophoblast cells from human term placenta. LAT1 and LAT2 transporters are highly expressed in the MVM of the syncytiotrophoblast layer at term. LAT2 is also localised in the basal membrane and in endothelial cells lining the fetal capillaries. Measurements in isolated MVM vesicles indicate that System L transporter expression and activity is not influenced by maternal BMI. CONCLUSIONS: LAT1 and LAT2 are present and functional in the syncytiotrophoblast MVM, whereas LAT2 is also expressed in the BM and in the fetal capillary endothelium. In contrast to placental System A and beta amino acid transporters, MVM System L activity is unaffected by maternal overweight/obesity.

Increased glucose and placental GLUT-1 in large infants of obese nondiabetic mothers.

OBJECTIVE: Obese women are at increased risk to deliver a large infant, however, the underlying mechanisms are poorly understood. Fetal glucose availability is critically dependent on placental transfer and is linked to fetal growth by regulating the release of fetal growth hormones such as insulin. We hypothesized that (1) umbilical vein glucose and insulin levels and (2) placental glucose transporter (GLUT) expression and activity are positively correlated with early pregnancy maternal body mass index and infant birthweight. STUDY DESIGN: Subjects in this prospective observational cohort study were nondiabetic predominantly Hispanic women delivered at term. Fasting maternal and umbilical vein glucose and insulin concentrations were determined in 29 women with varying early pregnancy body mass index (range, 18.0-54.3) who delivered infants with birthweights ranging from 2800-4402 g. We isolated syncytiotrophoblast microvillous and basal plasma membranes from 33 placentas and determined the expression of GLUT-1 and -9 (Western blot) and glucose uptake (radiolabeled glucose). RESULTS: Birthweight was positively correlated with umbilical vein glucose and insulin and maternal body mass index. Umbilical vein glucose levels were positively correlated with placental weight and maternal body mass index, but not with maternal fasting glucose. Basal plasma membranes GLUT-1 expression was positively correlated with birthweight. In contrast, syncytiotrophoblast microvillous GLUT-1 and -9, basal plasma membranes GLUT-9 expression and syncytiotrophoblast microvillous and basal plasma membranes glucose transport activity were not correlated with birthweight. CONCLUSION: Because maternal fasting glucose levels and placental glucose transport capacity were not increased in obese women delivering larger infants, we speculate that increased placental size promotes glucose delivery to these fetuses.

Differential regulation of placental amino acid transport by saturated and unsaturated fatty acids.

Fatty acids are critical for normal fetal development but may also influence placental function. We have previously reported that oleic acid (OA) stimulates amino acid transport in primary human trophoblasts (PHTs). In other tissues, saturated and unsaturated fatty acids have distinct effects on cellular signaling, for instance, palmitic acid (PA) but not OA reduces IκBα expression. We hypothesized that saturated and unsaturated fatty acids differentially affect trophoblast amino acid transport and cellular signaling. To test this hypothesis, PHTs were cultured in docosahexaenoic acid (DHA; 50 µM), OA (100 µM), or PA (100 µM). DHA and OA were also combined to test whether DHA could counteract the OA stimulatory effect on amino acid transport. The effects of fatty acids were compared against a vehicle control. Amino acid transport was measured by isotope-labeled tracers. Activation of inflammatory-related signaling pathways and the mechanistic target of rapamycin (mTOR) pathway were determined by Western blot analysis. Exposure of PHTs to DHA for 24 h reduced amino acid transport and phosphorylation of p38 MAPK, STAT3, mTOR, eukaryotic initiation factor 4E-binding protein 1, and ribosomal protein (rp)S6. In contrast, OA increased amino acid transport and phosphorylation of ERK, mTOR, S6 kinase 1, and rpS6. The combination of DHA with OA increased amino acid transport and rpS6 phosphorylation. PA did not affect amino acid transport but reduced IκBα expression. In conclusion, these fatty acids differentially regulated placental amino acid transport and cellular signaling. Taken together, these findings suggest that dietary fatty acids could alter the intrauterine environment by modifying placental function, thereby having long-lasting effects on the developing fetus.

Increasing maternal body mass index is associated with systemic inflammation in the mother and the activation of distinct placental inflammatory pathways.

Obese pregnant women have increased levels of proinflammatory cytokines in maternal circulation and placental tissues. However, the pathways contributing to placental inflammation in obesity are largely unknown. We tested the hypothesis that maternal body mass index (BMI) was associated with elevated proinflammatory cytokines in maternal and fetal circulations and increased activation of placental inflammatory pathways. A total of 60 women of varying pre-/early pregnancy BMI, undergoing delivery by Cesarean section at term, were studied. Maternal and fetal (cord) plasma were collected for analysis of insulin, leptin, IL-1beta, IL-6, IL-8, monocyte chemoattractant protein (MCP) 1, and TNFalpha by multiplex ELISA. Activation of the inflammatory pathways in the placenta was investigated by measuring the phosphorylated and total protein expression of p38-mitogen-activated protein kinase (MAPK), c-Jun-N-terminal kinase (JNK)-MAPK, signal transducer-activated transcription factor (STAT) 3, caspase-1, IL-1beta, IkappaB-alpha protein, and p65 DNA-binding activity. To determine the link between activated placental inflammatory pathways and elevated maternal cytokines, cultured primary human trophoblast (PHT) cells were treated with physiological concentrations of insulin, MCP-1, and TNFalpha, and inflammatory signaling analyzed by Western blot. Maternal BMI was positively correlated with maternal insulin, leptin, MCP-1, and TNFalpha, whereas only fetal leptin was increased with BMI. Placental phosphorylation of p38-MAPK and STAT3, and the expression of IL-1beta protein, were increased with maternal BMI; phosphorylation of p38-MAPK was also correlated with birth weight. In contrast, placental NFkappaB, JNK and caspase-1 signaling, and fetal cytokine levels were unaffected by maternal BMI. In PHT cells, p38-MAPK was activated by MCP-1 and TNFalpha, whereas STAT3 phosphorylation was increased following TNFalpha treatment. Maternal BMI is associated with elevated maternal cytokines and activation of placental p38-MAPK and STAT3 inflammatory pathways, without changes in fetal systemic inflammatory profile. Activation of p38-MAPK by MCP-1 and TNFalpha, and STAT3 by TNFalpha, suggests a link between elevated proinflammatory cytokines in maternal plasma and activation of placental inflammatory pathways. We suggest that inflammatory processes associated with elevated maternal BMI may influence fetal growth by altering placental function.

Does Developing Interpregnancy Hypertension Affect the Recurrence Risk of Preeclampsia? A Population-Based Cohort Study.

BACKGROUND: Preeclampsia in a first pregnancy is a strong risk factor for preeclampsia in a second pregnancy. Whether chronic hypertension developed after a first pregnancy (interpregnancy hypertension) affects the recurrence risk of preeclampsia is unknown. METHODS: This is a population-based cohort study of 391,645 women with their first and second singleton births between 2006 and 2017. Exposure groups were women with preeclampsia in their first pregnancy, interpregnancy hypertension, or both risk factors. Women with neither risk factor were used as a reference group. We calculated the adjusted relative risk (aRR) with 95% confidence intervals (CIs) for overall preeclampsia in the second pregnancy as well as preterm (<37 gestational weeks) and term (≥37 gestational weeks) subgroups of the disease. RESULTS: Women with preeclampsia in their first pregnancy who did or did not develop interpregnancy hypertension had rates of preeclampsia in their second pregnancy of 21.5% and 13.6%, respectively. In the same population, the corresponding rates of preterm preeclampsia were 5.5% and 2.6%, respectively. After adjusting for maternal factors, women with preeclampsia in their first pregnancy who developed interpregnancy hypertension and those who did not have almost the same risk of overall preeclampsia in their second pregnancy (aRRs with 95% CIs: 14.51; 11.77-17.89 and 12.83; 12.09-13.62, respectively). However, preeclampsia in the first pregnancy and interpregnancy hypertension had a synergistic interaction on the outcome of preterm preeclampsia (aRR with 95% CI 26.66; 17.44-40.80). CONCLUSIONS: Women with previous preeclampsia who developed interpregnancy hypertension had a very high rate of preterm preeclampsia in a second pregnancy, and the two risk factors had a synergistic interaction.

Novel Associations Between Mid-Pregnancy Cardiovascular Biomarkers and Preeclampsia: An Explorative Nested Case-Control Study.

Prediction of women at high risk of preeclampsia is important for prevention and increased surveillance of the disease. Current prediction models need improvement, particularly with regard to late-onset preeclampsia. Preeclampsia shares pathophysiological entities with cardiovascular disease; thus, cardiovascular biomarkers may contribute to improving prediction models. In this nested case-control study, we explored the predictive importance of mid-pregnancy cardiovascular biomarkers for subsequent preeclampsia. We included healthy women with singleton pregnancies who had donated blood in mid-pregnancy (~ 18 weeks' gestation). Cases were women with subsequent preeclampsia (n = 296, 10% of whom had early-onset preeclampsia [< 34 weeks]). Controls were women who had healthy pregnancies (n = 333). We collected data on maternal, pregnancy, and infant characteristics from medical records. We used the Olink cardiovascular II panel immunoassay to measure 92 biomarkers in the mid-pregnancy plasma samples. The Boruta algorithm was used to determine the predictive importance of the investigated biomarkers and first-trimester pregnancy characteristics for the development of preeclampsia. The following biomarkers had confirmed associations with early-onset preeclampsia (in descending order of importance): placental growth factor (PlGF), matrix metalloproteinase (MMP-12), lectin-like oxidized LDL receptor 1, carcinoembryonic antigen-related cell adhesion molecule 8, serine protease 27, pro-interleukin-16, and poly (ADP-ribose) polymerase 1. The biomarkers that were associated with late-onset preeclampsia were BNP, MMP-12, alpha-L-iduronidase (IDUA), PlGF, low-affinity immunoglobulin gamma Fc region receptor II-b, and T cell surface glycoprotein. Our results suggest that MMP-12 is a promising novel preeclampsia biomarker. Moreover, BNP and IDUA may be of value in enhancing prediction of late-onset preeclampsia.

Differential gene expression in two consecutive pregnancies between same sex siblings and implications on maternal constraint.

The objective of this study was to investigate how placental gene expression differs in two consecutive pregnancies in same sex siblings, and its possible association with the "maternal constraint" hypothesis. Material was gathered from the BASIC study (Biological, Affect, Stress, Imaging, and Cognition in Pregnancy and the Puerperium), a population based prospective study that was started in 2009 in Uppsala. Over 900 specimens of placenta biopsies were collected and out of these 10 women gave birth twice, to the same sex child, and were included in this study. The total RNA was isolated and prepared from frozen villous tissue from the placenta and further analyzed by use of Ion AmpliSeq Human Transcriptome Gene Expression kit. A total of 234 genes differed significantly between the first and second pregnancy placentas, when adjusting for delivery mode, maternal BMI and gestational age. Of special interest was the down-regulated group of genes in the second pregnancy. Exemplified by Pentraxin 3, SRY-Box Transcription Factor 9, and Serum Amyloid A1, which all were associated with biological processes involved in the immune system and inflammation. Further, protein-protein interaction analysis visualized them as hub genes interacting with several of the other differentially expressed genes. How these altered gene expressions affect maternal constraint during pregnancy needs further validation in lager study cohorts and also future validation in functional assays.

Oleic acid stimulates system A amino acid transport in primary human trophoblast cells mediated by toll-like receptor 4.

Obese women have an increased risk to deliver large babies. However, the mechanisms underlying fetal overgrowth in these pregnancies are not well understood. Obese pregnant women typically have elevated circulating lipid levels. We tested the hypothesis that fatty acids stimulate placental amino acid transport, mediated via toll-like receptor 4 (TLR4) and mammalian target of rapamycin (mTOR) signaling pathways. Circulating NEFA levels and placental TLR4 expression were assessed in women with varying prepregnancy body mass index (BMI). The effects of oleic acid on system A and system L amino acid transport, and on the activation of the mTOR (4EBP1, S6K1, rpS6), TLR4 (IĸB, JNK, p38 MAPK), and STAT3 signaling pathways were determined in cultured primary human trophoblast cells. Maternal circulating NEFAs (n = 33), but not placental TLR4 mRNA expression (n = 16), correlated positively with BMI (P < 0.05). Oleic acid increased trophoblast JNK and STAT3 phosphorylation (P < 0.05), whereas mTOR activity was unaffected. Furthermore, oleic acid doubled trophoblast system A activity (P < 0.05), without affecting system L activity. siRNA-mediated silencing of TLR4 expression prevented the stimulatory effect of oleic acid on system A activity. Our data suggest that maternal fatty acids can increase placental nutrient transport via TLR4, thereby potentially affecting fetal growth.

Spatial transcriptomics of human placentas reveal distinct RNA patterns associated with morphology and preeclampsia.

Spatial transcriptomics (ST) maps RNA level patterns within a tissue. This technology has not been previously applied to human placental tissue. We demonstrate analysis of human placental samples with ST. Unsupervised clustering revealed that distinct RNA patterns were found corresponding to different morphological structures. Additionally, when focusing upon terminal villi and hemoglobin associated structures, RNA levels differed between placentas from full term healthy pregnancies and those complicated by preeclampsia. The results from this study can provide a benchmark for future ST studies in placenta.

Study protocol: The cross-sectional Uppsala weight gain in pregnancy study (VIGA study).

Background: More than two in five Swedish women are overweight or obese when becoming pregnant. Maternal overweight or obesity and excessive pregnancy weight gain are associated with several adverse pregnancy outcomes. The underlying mechanisms that link maternal adiposity, diet, exercise, pregnancy weight gain with pregnancy outcome are incompletely understood. Methods: We describe the design for a cross-sectional study of pregnant women at Uppsala University Hospital, Sweden. All participants delivered by elective cesarean section before the onset of labor. At inclusion, participants answered two questionnaires concerning their dietary and exercise habits. Fasting maternal blood samples (buffy coat, plasma, serum) were collected. During the cesarean section, biopsies of maternal subcutaneous and visceral adipose tissues were obtained. Placental tissue was collected after delivery. All biological samples were processed as soon as possible, frozen on dry ice, and stored at -70 °C. Pregnancy outcomes and supplementary maternal characteristics were collected from medical records. Results: In total, 143 women were included in the study. Of these women, 33.6% were primiparous, 46.2% had a pre-pregnancy body mass index (BMI) over 25 kg/m2, and 11.2% of the offspring were born large for gestational age (LGA). Complete collection, that is both questionnaires and all types of biological samples, was obtained from 81.1% of the participants. Conclusions: This study is expected to provide a resource for exploration of the associations between maternal weight, diet, exercise, pregnancy weight gain, and pregnancy outcome. Results from this study will be published in peer-reviewed, international scientific journals. This study was approved by the Regional Ethics Review Board in Uppsala (approval no 2014/353) and with an amendment by the Swedish Ethical Review Authority (approval no 2020-05844).

Early Mid-pregnancy Blood-Based Proteins as Possible Biomarkers of Increased Infant Birth Size in Sex-Stratified Analyses.

The objective of this study was to evaluate the associations of 92 maternal blood-based proteins with increased infant birth size. The study was performed at the Uppsala University Hospital, Sweden, and included 857 mother and child dyads. The mean age of the women was 30.3 years, and 53.2% were nulliparous. Blood samples were collected at mean 18 + 2 weeks' gestation, and the Olink cardiovascular II panel was used to measure 92 proteins, either known to be or suspected to be markers of cardiovascular and inflammatory disease in humans. Multiple linear regression models adjusted for maternal age, parity, pre-conception BMI, height, and smoking were performed to evaluate the association of each individual protein with infant birth size. We also performed sex-stratified analyses. Eight proteins (Matrix metalloproteinase-12 (MMP-12), Prostasin (PRSS8), Adrenomedullin (ADM), Pappalysin-1 (PAPP-A), Angiotensin-converting enzyme 2 (ACE2), Sortilin (SORT1), Lectin-like oxidized LDL receptor 1 (LOX-1), and Thrombomodulin (TM)) were associated with infant birth size after false discovery rate adjustment. In the analyses including only female infants, ten proteins (MMP-12, Growth/differentiation factor 2 (GDF-2), PRSS8, SORT1, ADM, Interleukin-1 receptor antagonist protein (IL-1ra), Leptin (LEP), ACE2, TM, and Tumor necrosis factor receptor superfamily member 11A (TNFRSF11A)) were associated with infant birth size. Two proteins (PAPP-A and PRSS8) were associated with infant birth size among male infants. Our study suggests several proteins as potential biomarkers for increased birth weight, and our findings could act as a base for future research to identify new potential markers that could be added to improve screening for large infants.