Plasma cross-gestational sphingolipidomic analyses reveal potential first trimester biomarkers of preeclampsia

BMA-based Mendelian randomization identifies blood metabolites as causal candidates in pregnancy-induced hypertension

Pregnancy-induced hypertension (PIH), a prominent determinant of maternal mortality and morbidity worldwide, is hindered by the absence of efficacious biomarkers for early diagnosis, contributing to suboptimal outcomes. Here, we explored potential causal relationships between blood metabolites and the risk of PIH using Mendelian randomization (MR). We employed a two-sample univariable MR approach to empirically estimate the causal relationships between 249 circulating metabolites and PIH. Inverse variance weighted, MR-egger, weight median, simple mode, and weighted mode methods were used for causal estimates. The exposure-to-outcome directionality was confirmed with the MR Steiger test. The Bayesian model averaging MR (MR-BMA) method was applied to detect the predominant causal metabolic traits with alignment for pleiotropy effects. In the primary analysis, analyzing 249 metabolites, we identified 25 causally linked to PIH, including 11 lipid-related traits and 6 associated with fatty acid (un)saturation. Importantly, MR-BMA analyses corroborated the total concentration of branched-chain amino acids(total-BCAA) to be the highest rank causal metabolite, followed by leucine (Leu), phospholipids to total lipids ratio in medium LDL (M-LDL-PL-pct), and Val (all P < 0.05). The directionality of causality predicted by univariable MR and MR-BMA for these metabolites remained consistent. This study highlights the causal connection between metabolites and PIH risk. It highlighted BCAAs as the strongest causal candidates warranting further investigation. Since PIH typically occurs in the second and third trimesters, extending these findings could inform earlier strategies to reduce its risk. Directed acyclic graph of the MR framework investigating the causal relationship between metabolites and PIH. MR: Mendelian randomization; GIVs: genetic instrument variables; SNPs: single-nucleotide polymorphism; IVW: inverse variance weighted; WM: weighted median; PIH: pregnancy-induced hypertension; SM: significant metabolite; MR-BMA: Bayesian model averaging MR.

Differences in HDL Remodeling during Healthy Pregnancy and Pregnancy with Cardiometabolic Complications

This study investigated the longitudinal trajectory of changes in antioxidative and anti-inflammatory high-density lipoprotein (HDL) components during healthy pregnancy and pregnancy with cardiometabolic complications. We recruited and longitudinally followed 84 women with healthy pregnancies and 46 pregnant women who developed cardiometabolic pregnancy complications (gestational diabetes mellitus and hypertensive disorders of pregnancy). Their general lipid profiles, oxidative stress status, inflammatory status, and antioxidative and anti-inflammatory HDL components were analyzed. The results of our study confirmed the expected trajectory for the routine lipid parameters. Our study results indicate more intensive oxidative stress and a higher level of inflammation in the group with complications compared with the control group. Sphingosine-1-phosphate (S1P) was significantly lower in the first trimester in the group with complications compared with the control group (p < 0.05). We did not find significant differences in the apolipoprotein A1 (Apo A1) concentrations in the first trimester between the control group and the group with complications, but in the second and third trimesters, the group with complications had significantly higher concentrations (p < 0.001, p < 0.05, respectively). The S1P, paraoxonase 1 (PON1), and serum amyloid A (SAA) concentrations were significantly lower in the group with complications in the first trimester. During the second trimester, only the SAA concentrations were identified as significantly lower in the group with complications compared with the control group, while in the third trimester, the PON1, apolipoprotein M (Apo M), and SAA concentrations were all significantly lower in the group with complications. Through a multivariate binary logistic regression analysis, the S1P concentration in the first trimester was distinguished as an HDL-associated marker independently associated with cardiometabolic pregnancy complications. In conclusion, our study results showed that HDL remodeling differs between healthy pregnancies and pregnancies with maternal cardiometabolic complications, with changed HDL composition and functionality consequently impacting its biological functionality in the latter case.

Paradoxes: Cholesterol and Hypoxia in Preeclampsia

Preeclampsia, a hypertensive disease of pregnancy of unknown etiology, is intensely studied as a model of cardiovascular disease (CVD) not only due to multiple shared pathologic elements but also because changes that develop over decades in CVD appear and resolve within days in preeclampsia. Those affected by preeclampsia and their offspring experience increased lifetime risks of CVD. At the systemic level, preeclampsia is characterized by increased cellular, membrane, and blood levels of cholesterol; however, cholesterol-dependent signaling, such as canonical Wnt/βcatenin, Hedgehog, and endothelial nitric oxide synthase, is downregulated indicating a cholesterol deficit with the upregulation of cholesterol synthesis and efflux. Hypoxia-related signaling in preeclampsia also appears to be paradoxical with increased Hypoxia-Inducible Factors in the placenta but measurably increased oxygen in maternal blood in placental villous spaces. This review addresses the molecular mechanisms by which excessive systemic cholesterol and deficient cholesterol-dependent signaling may arise from the effects of dietary lipid variance and environmental membrane modifiers causing the cellular hypoxia that characterizes preeclampsia.

Metabolomic prediction of severe maternal and newborn complications in preeclampsia

INTRODUCTION

Preeclampsia (PreE) remains a major source of maternal and newborn complications. Prenatal prediction of these complications could significantly improve pregnancy management.

OBJECTIVES

Using metabolomic analysis we investigated the prenatal prediction of maternal and newborn complications in early and late PreE and investigated the pathogenesis of such complications.

METHODS

Serum samples from 76 cases of PreE (36 early-onset and 40 late-onset), and 40 unaffected controls were collected. Direct Injection Liquid Chromatography-Mass Spectrometry combined with Nuclear Magnetic Resonance (NMR) spectroscopy was performed. Logistic regression analysis was used to generate models for prediction of adverse maternal and neonatal outcomes in patients with PreE. Metabolite set enrichment analysis (MSEA) was used to identify the most dysregulated metabolites and pathways in PreE.

RESULTS

Forty-three metabolites were significantly altered (p < 0.05) in PreE cases with maternal complications and 162 metabolites were altered in PreE cases with newborn adverse outcomes. The top metabolite prediction model achieved an area under the receiver operating characteristic curve (AUC) = 0.806 (0.660-0.952) for predicting adverse maternal outcomes in early-onset PreE, while the AUC for late-onset PreE was 0.843 (0.712-0.974). For the prediction of adverse newborn outcomes, regression models achieved an AUC = 0.828 (0.674-0.982) in early-onset PreE and 0.911 (0.828-0.994) in late-onset PreE. Profound alterations of lipid metabolism were associated with adverse outcomes.

CONCLUSION

Prenatal metabolomic markers achieved robust prediction, superior to conventional markers for the prediction of adverse maternal and newborn outcomes in patients with PreE. We report for the first-time the prediction and metabolomic basis of adverse maternal and newborn outcomes in patients with PreE.

Non-regulated haloaromatic water disinfection byproducts act as endocrine and lipid disrupters in human placental cells

The disinfection of drinking water generates hundreds of disinfection byproducts (DBPs), including haloaromatic DBPs. These haloaromatic DBPs are suspected to be more toxic than haloaliphatic ones, and they are currently not regulated. This work investigates their toxicity and ability to interfere with estrogen synthesis in human placental JEG-3 cells, and their genotoxic potential in human alveolar A549 cells. Among the haloaromatic DBPs studied, halobenzoquinones (2,6-dichloro-1,4-benzoquinone (DCBQ) and 2,6-dibromo-1,4-benzoquinone (DBBQ)) showed the highest cytotoxicity (EC50: 18-26 μg/mL). They induced the generation of very high levels of reactive oxygen species (ROS) and up-regulated the expression of genes involved in estrogen synthesis (cyp19a1, hsd17b1). Increased ROS was linked to significant depletion of polyunsaturated lipid species from inner cell membranes. The other DBPs tested showed low or no significant cytotoxicity (EC50 ≥ 100 μg/mL), while 2,4,6-trichloro-phenol (TCP), 2,4,6-tribromo-phenol (TBP) and 3,5-dibromo-4-hydroxybenzaldehyde (DCHB) induced the formation of micronuclei at concentrations much higher than those typically found in water (100 μg/mL). This study reveals the different modes of action of haloaromatic DBPs, and highlights the toxic potential of halobenzoquinones, which had a significant impact on the expression of placenta steroid metabolism related genes and induce oxidative stress, implying potential adverse health effects.

Ceramides during Pregnancy and Obstetrical Adverse Outcomes

Ceramides are a group of sphingolipids located in the external plasma membrane layer and act as messengers in cellular pathways such as inflammatory processes and apoptosis. Plasma ceramides are biomarkers of cardiovascular disease, type 2 diabetes mellitus, Alzheimer's disease, various autoimmune conditions and cancer. During pregnancy, ceramides play an important role as stress mediators, especially during implantation, delivery and lactation. Based on the current literature, plasma ceramides could be potential biomarkers of obstetrical adverse outcomes, although their role in metabolic pathways under such conditions remains unclear. This review aims to present current studies that examine the role of ceramides during pregnancy and obstetrical adverse outcomes, such as pre-eclampsia, gestational diabetes mellitus and other complications.

Effects of Pregnancy on Plasma Sphingolipids Using a Metabolomic and Quantitative Analysis Approach

Changes in the maternal metabolome, and specifically the maternal lipidome, that occur during pregnancy are relatively unknown. The objective of this investigation was to evaluate the effects of pregnancy on sphingolipid levels using metabolomics analysis followed by confirmational, targeted quantitative analysis. We focused on three subclasses of sphingolipids: ceramides, sphingomyelins, and sphingosines. Forty-seven pregnant women aged 18 to 50 years old participated in this study. Blood samples were collected on two study days for metabolomics analysis. The pregnancy samples were collected between 25 and 28 weeks of gestation and the postpartum study day samples were collected ≥3 months postpartum. Each participant served as their own control. These samples were analyzed using a Ultra-performance liquid chromatography/mass spectroscopy/mass spectroscopy (UPLC/MS/MS) assay that yielded semi-quantitative peak area values that were used to compare sphingolipid levels between pregnancy and postpartum. Following this lipidomic analysis, quantitative LC/MS/MS targeted/confirmatory analysis was performed on the same study samples. In the metabolomic analysis, 43 sphingolipid metabolites were identified and their levels were assessed using relative peak area values. These profiled sphingolipids fell into three categories: ceramides, sphingomyelins, and sphingosines. Of the 43 analytes measured, 35 were significantly different during pregnancy (p < 0.05) (including seven ceramides, 26 sphingomyelins, and two sphingosines) and 32 were significantly higher during pregnancy compared to postpartum. Following metabolomics, a separate quantitative analysis was performed and yielded quantified concentration values for 23 different sphingolipids, four of which were also detected in the metabolomics study. Quantitative analysis supported the metabolomics results with 17 of the 23 analytes measured found to be significantly different during pregnancy including 11 ceramides, four sphingomyelins, and two sphingosines. Fourteen of these were significantly higher during pregnancy. Our data suggest an overall increase in plasma sphingolipid concentrations with possible implications in endothelial function, gestational diabetes mellitus (GDM), intrahepatic cholestasis of pregnancy, and fetal development. This study provides evidence for alterations in maternal sphingolipid metabolism during pregnancy.

Bioactive lipid mediators in plasma are predictors of preeclampsia irrespective of aspirin therapy

There are few early biomarkers to identify pregnancies at risk of preeclampsia (PE) and abnormal placental function. In this cross-sectional study, we utilized targeted ultra-performance liquid chromatography-ESI MS/MS and a linear regression model to identify specific bioactive lipids that serve as early predictors of PE. Plasma samples were collected from 57 pregnant women prior to 24-weeks of gestation with outcomes of either PE (n = 26) or uncomplicated term pregnancies (n = 31), and the profiles of eicosanoids and sphingolipids were evaluated. Significant differences were revealed in the eicosanoid, (±)11,12 DHET, as well as multiple classes of sphingolipids; ceramides, ceramide-1-phosphate, sphingomyelin, and monohexosylceramides; all of which were associated with the subsequent development of PE regardless of aspirin therapy. Profiles of these bioactive lipids were found to vary based on self-designated race. Additional analyses demonstrated that PE patients can be stratified based on the lipid profile as to PE with a preterm birth linked to significant differences in the levels of 12-HETE, 15-HETE, and resolvin D1. Furthermore, subjects referred to a high-risk OB/GYN clinic had higher levels of 20-HETE, arachidonic acid, and Resolvin D1 versus subjects recruited from a routine, general OB/GYN clinic. Overall, this study shows that quantitative changes in plasma bioactive lipids detected by ultra-performance liquid chromatography-ESI-MS/MS can serve as an early predictor of PE and stratify pregnant people for PE type and risk.

A theoretical model of dietary lipid variance as the origin of primary ciliary dysfunction in preeclampsia

Serving as the cell's key interface in communicating with the outside world, primary cilia have emerged as an area of multidisciplinary research interest over the last 2 decades. Although the term "ciliopathy" was first used to describe abnormal cilia caused by gene mutations, recent studies focus on abnormalities of cilia that are found in diseases without clear genetic antecedents, such as obesity, diabetes, cancer, and cardiovascular disease. Preeclampsia, a hypertensive disease of pregnancy, is intensely studied as a model for cardiovascular disease partially due to many shared pathophysiologic elements, but also because changes that develop over decades in cardiovascular disease arise in days with preeclampsia yet resolve rapidly after delivery, thus providing a time-lapse view of the development of cardiovascular pathology. As with genetic primary ciliopathies, preeclampsia affects multiple organ systems. While aspirin delays the onset of preeclampsia, there is no cure other than delivery. The primary etiology of preeclampsia is unknown; however, recent reviews emphasize the fundamental role of abnormal placentation. During normal embryonic development, trophoblastic cells, which arise from the outer layer of the 4-day-old blastocyst, invade the maternal endometrium and establish extensive placental vascular connections between mother and fetus. In primary cilia of trophoblasts, Hedgehog and Wnt/catenin signaling operate upstream of vascular endothelial growth factor to advance placental angiogenesis in a process that is promoted by accessible membrane cholesterol. In preeclampsia, impaired proangiogenic signaling combined with an increase in apoptotic signaling results in shallow invasion and inadequate placental function. Recent studies show primary cilia in preeclampsia to be fewer in number and shortened with functional signaling abnormalities. Presented here is a model that integrates preeclampsia lipidomics and physiology with the molecular mechanisms of liquid-liquid phase separation in model membrane studies and the known changes in human dietary lipids over the last century to explain how changes in dietary lipids might reduce accessible membrane cholesterol and give rise to shortened cilia and defects in angiogenic signaling, which underlie placental dysfunction of preeclampsia. This model offers a possible mechanism for non-genetic dysfunction in cilia and proposes a proof-of-concept study to treat preeclampsia with dietary lipids.

Plasma Ceramide Concentrations in Full-Term Pregnancies Complicated with Gestational Diabetes Mellitus: A Case-Control Study

Ceramides, a sphingolipid group that acts as a messenger in cellular differentiation, proliferation, apoptosis and senescence, have been associated with cardiovascular disease and type 2 diabetes. The evidence for an association between ceramides and gestational diabetes mellitus (GDM) is scarce. This case-control study aimed to compare women with GDM with healthy, pregnant women in terms of plasma ceramide concentrations at the time of delivery. Ninety-two pregnant women were included in this case-control study, 29 in the GDM group and 63 in the control group. All women were admitted to a tertiary academic hospital for a full-term delivery. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was applied for the quantification of four molecular ceramides, namely Cer d18:1/16:0 (Cer16:0), Cer d18:1/18:0 (Cer18:0), Cer d18:1/24:0 (Cer24:0) and Cer d18:1/24:1 (Cer24:1) in plasma samples. The raw chromatographic data obtained from the LC-MS/MS analysis were processed using Analyst SCIEX (AB Sciex Pte. Ltd., USA). In a univariate statistical analysis, Cer24:0 concentration was significantly lower in the GDM group compared with the control group (p = 0.01). The present study demonstrated lower Cer24:0 concentrations in pregnancies complicated by GDM. Further prospective studies are required to enhance the results of this study.

Plasma S1P and Sphingosine are not Different Prior to Pre-Eclampsia in Women at High Risk of Developing the Disease

Sphingolipids like sphingosine-1-phosphate (S1P) have been implicated in the pathophysiology of pre-eclampsia. We hypothesized that plasma S1P would be increased in women at high risk of developing pre-eclampsia who subsequently develop the disease. Low circulating placental growth factor (PlGF) is known to be associated with development of pre-eclampsia; so further, we hypothesized that increased S1P would be associated with concurrently low PlGF. This was a case-control study using stored maternal blood samples from 14 to 24 weeks of pregnancy, collected from 95 women at increased risk of pre-eclampsia. Pregnancy outcome was classified as uncomplicated, preterm pre-eclampsia (<37 weeks), or term pre-eclampsia. Plasma lipids were extracted and analyzed by ultraperformance liquid chromatography coupled to electrospray ionization MS/MS to determine concentrations of S1P and sphingosine. Median plasma S1P was 0.339 nmol/ml, and median sphingosine was 6.77 nmol/l. There were no differences in the plasma concentrations of S1P or sphingosine in women who subsequently developed pre-eclampsia, no effect of gestational age, fetal sex, ethnicity, or the presence of pre-existing hypertension. There was a correlation between S1P and sphingosine plasma concentration (P < 0.0001). There was no relationship between S1P or sphingosine with PlGF. Previous studies have suggested that plasma S1P may be a biomarker of pre-eclampsia. In our larger study, we failed to demonstrate there are women at high risk of developing the disease. We did not show a relationship with known biomarkers of the disease, suggesting that S1P is unlikely to be a useful predictor of the development of pre-eclampsia later in pregnancy.

Tumor Necrosis Factor-α Induces a Preeclamptic-like Phenotype in Placental Villi via Sphingosine Kinase 1 Activation

Preeclampsia (PE) involves inadequate placental function. This can occur due to elevated pro-inflammatory tumor necrosis factor-α (TNF-α). In other tissues, TNF-α signals via sphingosine kinase 1 (SphK1). SphK1 hinders syncytial formation. Whether this occurs downstream of TNF-α signaling is unclear. We hypothesized that placental SphK1 levels are higher in PE and elevated TNF-α decreases syncytial function, increases syncytial shedding, and increases cytokine/factor release via SphK1 activity. Term placental biopsies were analyzed for SphK1 using immunofluorescence and qRT-PCR. Term placental explants were treated after 4 days of culture, at the start of syncytial regeneration, with TNF-α and/or SphK1 inhibitors, PF-543. Syncytialization was assessed by measuring fusion and chorionic gonadotropin release. Cell death and shedding were measured by lactate dehydrogenase release and placental alkaline phosphatase-positive shed particles. Forty-two cytokines were measured using multiplex assays. Placental SphK1 was increased in PE. Increased cell death, shedding, interferon-α2, IFN-γ-induced protein 10, fibroblast growth factor 2, and platelet-derived growth factor-AA release induced by TNF-α were reversed upon SphK1 inhibition. TNF-α increased the release of 26 cytokines independently of SphK1. TNF-α decreased IL-10 release and inhibiting SphK1 reversed this effect. Inhibiting SphK1 alone decreased TNF-α release. Hence, SphK1 partially mediates the TNF-α-induced PE placental phenotype, primarily through cell damage, shedding, and specific cytokine release.

Effects of Dicyclohexyl Phthalate Exposure on PXR Activation and Lipid Homeostasis in Mice

BACKGROUND

Exposure to plastic-associated endocrine disrupting chemicals (EDCs) has been associated with an increased risk of cardiovascular disease (CVD) in humans. However, the underlying mechanisms for this association are unclear. Many EDCs have been shown to function as ligands of the nuclear receptor pregnane X receptor (PXR), which functions as xenobiotic sensor but also has pro-atherogenic effects in vivo.

OBJECTIVE

We sought to investigate the contribution of PXR to the adverse effects dicyclohexyl phthalate (DCHP), a widely used phthalate plasticizer, on lipid homeostasis and CVD risk factors.

METHODS

Cell-based assays, primary organoid cultures, and PXR conditional knockout and PXR-humanized mouse models were used to investigate the impact of DCHP exposure on PXR activation and lipid homeostasis in vitro and in vivo. Targeted lipidomics were performed to measure circulating ceramides, novel predictors for CVD.

RESULTS

DCHP was identified as a potent PXR-selective agonist that led to higher plasma cholesterol levels in wild-type mice. DCHP was then demonstrated to activate intestinal PXR to elicit hyperlipidemia by using tissue-specific PXR-deficient mice. Interestingly, DCHP exposure also led to higher circulating ceramides in a PXR-dependent manner. DCHP-mediated PXR activation stimulated the expression of intestinal genes mediating lipogenesis and ceramide synthesis. Given that PXR exhibits considerable species-specific differences in receptor pharmacology, PXR-humanized mice were also used to replicate these findings.

DISCUSSION

Although the adverse health effects of several well-known phthalates have attracted considerable attention, little is known about the potential impact of DCHP on human health. Our studies demonstrate that DCHP activated PXR to induce hypercholesterolemia and ceramide production in mice. These results indicate a potentially important role of PXR in contributing to the deleterious effects of plastic-associated EDCs on cardiovascular health in humans. Testing PXR activation should be considered for risk assessment of phthalates and other EDCs. https://doi.org/10.1289/EHP9262.

The maternal blood lipidome is indicative of the pathogenesis of severe preeclampsia

Preeclampsia is a pregnancy-specific syndrome characterized by hypertension and proteinuria after 20 weeks of gestation. However, it is not well understood what lipids are involved in the development of this condition, and even less is known how these lipids mediate its formation. To reveal the relationship between lipids and preeclampsia, we conducted lipidomic profiling of maternal sera of 44 severe preeclamptic and 20 healthy pregnant women from a multiethnic cohort in Hawaii. Correlation network analysis showed that oxidized phospholipids have increased intercorrelations and connections in preeclampsia, whereas other lipids, including triacylglycerols, have reduced network correlations and connections. A total of 10 lipid species demonstrate significant changes uniquely associated with preeclampsia but not any other clinical confounders. These species are from the lipid classes of lysophosphatidylcholines, phosphatidylcholines (PCs), cholesteryl esters, phosphatidylethanolamines, lysophosphatidylethanolamines, and ceramides. A random forest classifier built on these lipids shows highly accurate and specific prediction (F1 statistic = 0.94; balanced accuracy = 0.88) of severe preeclampsia, demonstrating their potential as biomarkers for this condition. These lipid species are enriched in dysregulated biological pathways, including insulin signaling, immune response, and phospholipid metabolism. Moreover, causality inference shows that various PCs and lysophosphatidylcholines mediate severe preeclampsia through PC 35:1e. Our results suggest that the lipidome may play a role in the pathogenesis and serve as biomarkers of severe preeclampsia.

Sphingolipids in HDL - Potential markers for adaptation to pregnancy?

Plasma high density lipoprotein (HDL) exhibits many functions that render it an effective endothelial protective agent and may underlie its potential role in protecting the maternal vascular endothelium during pregnancy. In non-pregnant individuals, the HDL lipidome is altered in metabolic disease compared to healthy individuals and is linked to reduced cholesterol efflux, an effect that can be reversed by lifestyle management. Specific sphingolipids such as sphingosine-1-phosphate (S1P) have been shown to mediate the vaso-dilatory effects of plasma HDL via interaction with the endothelial nitric oxide synthase pathway. This review describes the relationship between plasma HDL and vascular function during healthy pregnancy and details how this is lost in pre-eclampsia, a disorder of pregnancy associated with widespread endothelial dysfunction. Evidence of a role for HDL sphingolipids, in particular S1P and ceramide, in cardiovascular disease and in healthy pregnancy and pre-eclampsia is discussed. Available data suggest that HDL-S1P and HDL-ceramide can mediate vascular protection in healthy pregnancy but not in preeclampsia. HDL sphingolipids thus are of potential importance in the healthy maternal adaptation to pregnancy.

Physiological and pathological functions of sphingolipids in pregnancy

Signaling by the bioactive sphingolipid, sphingosine 1-phosphate (S1P), and its precursors are emerging areas in pregnancy research. S1P and ceramide levels increase towards end of gestation, suggesting a physiological role in parturition. However, high levels of circulating S1P and ceramide are correlated with pregnancy disorders such as preeclampsia, gestational diabetes mellitus and intrauterine growth restriction. Expression of placental and decidual enzymes that metabolize S1P and S1P receptors are also dysregulated during pregnancy complications. In this review, we provide an in-depth examination of the signaling mechanism of S1P and ceramide in various reproductive tissues during gestation. These factors determine implantation and early pregnancy success by modulating corpus luteum function from progesterone production to luteolysis through to apoptosis. We also highlight the role of S1P through receptor signaling in inducing decidualization and angiogenesis in the decidua, as well as regulating extravillous trophoblast migration to anchor the placenta into the uterine wall. Recent advances on the role of the S1P:ceramide rheostat in controlling the fate of villous trophoblasts and the role of S1P as a negative regulator of trophoblast syncytialization to a multinucleated placental barrier are discussed. This review also explores the role of S1P in anti-inflammatory and pro-inflammatory signaling, its role as a vasoconstrictor, and the effects of S1P metabolizing enzymes and receptors in pregnancy.

Mid-gestation serum lipidomic profile associations with spontaneous preterm birth are influenced by body mass index

Spontaneous preterm birth (sPTB) is a major cause of infant morbidity and mortality. While metabolic changes leading to preterm birth are unknown, several factors including dyslipidemia and inflammation have been implicated and paradoxically both low (<18.5 kg/m²) and high (>30 kg/m²) body mass indices (BMIs) are risk factors for this condition. The objective of the study was to identify BMI-associated metabolic perturbations and potential mid-gestation serum biomarkers of preterm birth in a cohort of underweight, normal weight and obese women experiencing either sPTB or full-term deliveries (n = 102; n = 17/group). For this purpose, we combined untargeted metabolomics and lipidomics with targeted metabolic profiling of major regulators of inflammation and metabolism, including oxylipins, endocannabinoids, bile acids and ceramides. Women who were obese and had sPTB showed elevated oxidative stress and dyslipidemia characterized by elevated serum free fatty acids. Women who were underweight-associated sPTB also showed evidence of dyslipidemia characterized by elevated phospholipids, unsaturated triglycerides, sphingomyelins, cholesteryl esters and long-chain acylcarnitines. In normal weight women experiencing sPTB, the relative abundance of 14(15)-epoxyeicosatrienoic acid and 14,15-dihydroxyeicosatrienoic acids to other regioisomers were altered at mid-pregnancy. This phenomenon is not yet associated with any biological process, but may be linked to estrogen metabolism. These changes were differentially modulated across BMI groups. In conclusion, using metabolomics we observed distinct BMI-dependent metabolic manifestations among women who had sPTB. These observations suggest the potential to predict sPTB mid-gestation using a new set of metabolomic markers and BMI stratification. This study opens the door to further investigate the role of cytochrome P450/epoxide hydrolase metabolism in sPTB.

High-throughput quantitation of serological ceramides/dihydroceramides by LC/MS/MS: Pregnancy baseline biomarkers and potential metabolic messengers

Ceramides and dihydroceramides are sphingolipids that present in abundance at the cellular membrane of eukaryotes. Although their metabolic dysregulation has been implicated in many diseases, our knowledge about circulating ceramide changes during the pregnancy remains limited. In this study, we present the development and validation of a high-throughput liquid chromatography-tandem mass spectrometric method for simultaneous quantification of 16 ceramides and 10 dihydroceramides in human serum within 5 min. by using stable isotope-labeled ceramides as internal standards. This method employs a protein precipitation method for high throughput sample preparation, reverse phase isocratic elusion for chromatographic separation, and Multiple Reaction Monitoring for mass spectrometric detection. To qualify for clinical applications, our assay has been validated against the FDA guidelines for Lower Limit of Quantitation (1 nM), linearity (R²>0.99), precision (imprecision<15 %), accuracy (inaccuracy<15 %), extraction recovery (>90 %), stability (>85 %), and carryover (<0.01 %). With enhanced sensitivity and specificity from this method, we have, for the first time, determined the serological levels of ceramides and dihydroceramides to reveal unique temporal gestational patterns. Our approach could have value in providing insights into disorders of pregnancy.

Effect of bilingualism on visual tracking attention and resistance to distraction

Speaking more than one language has been associated with enhanced cognitive capacities. Here we evaluated whether bilingual individuals have advantages in visual tracking attention. Adult bilingual (n = 35) and monolingual (n = 35) participants were tested in the Multiple Object Tracking task (MOT). In one condition, the MOT was performed by itself establishing the baseline performance of each group, and in the other condition, it was performed while participants counted backward out loud in their mother tongue. At baseline, the average speed tracking threshold of bilinguals was not better than that of the monolinguals. Importantly, for bilinguals, counting backward decreased their threshold by only 15%, but, for monolinguals, it decreased it three times as much. This result suggests that bilingualism confers advantages to visual tracking attention when dual tasking is required, extending the evidence that bilingualism affords cognitive benefits beyond verbal communication.

Sexual Dimorphism of Metabolomic Profile in Arterial Hypertension

Metabolomic studies have demonstrated the existence of biological signatures in blood of patients with arterial hypertension, but no study has hitherto reported the sexual dimorphism of these signatures. We compared the plasma metabolomic profiles of 28 individuals (13 women and 15 men) with essential arterial hypertension with those of a healthy control group (18 women and 18 men), using targeted metabolomics. Among the 188 metabolites explored, 152 were accurately measured. Supervised OPLS-DA (orthogonal partial least squares-discriminant analysis) showed good predictive performance for hypertension in both sexes (Q2cum = 0.59 in women and 0.60 in men) with low risk of overfitting (p-value-CV ANOVA = 0.004 in women and men). Seventy-five and 65 discriminant metabolites with a VIP (variable importance for the projection) greater than 1 were evidenced in women and men, respectively. Both sexes showed a considerable increase in phosphatidylcholines, a decrease in C16:0 with an increase in C28:1 lysophosphatidylcholines, an increase in sphingomyelins, as well as an increase of symmetric dimethylarginine (SDMA), acetyl-ornithine and hydroxyproline. Twenty-nine metabolites, involved in phospholipidic and cardiac remodeling, arginine/nitric oxide pathway and antihypertensive and insulin resistance mechanisms, discriminated the metabolic sexual dimorphism of hypertension. Our results highlight the importance of sexual dimorphism in arterial hypertension.

Sphingolipid Signature of Human Feto-Placental Vasculature in Preeclampsia

Bioactive sphingolipids are emerging as key regulators of vascular function and homeostasis. While most of the clinical studies have been devoted to profile circulating sphingolipids in maternal plasma, little is known about the role of the sphingolipid at the feto-placental vasculature, which is in direct contact with the offspring circulation. Our study aims to compare the sphingolipid profile of normal with preeclamptic (PE) placental chorionic arteries and isolated endothelial cells, with the goal of unveiling potential underlying pathomechanisms in the vasculature. Dihydrosphingosine and sphingomyelin (SM) concentrations (C16:0-, C18:0-, and C24:0- sphingomyelin) were significantly increased in chorionic arteries of preeclamptic placentas, whereas total ceramide, although showing a downward trend, were not statistically different. Moreover, RNA and immunofluorescence analysis showed impaired sphingosine-1-phosphate (S1P) synthesis and signaling in PE vessels. Our data reveal that the exposure to a deranged maternal intrauterine environment during PE alters the sphingolipid signature and gene expression on the fetal side of the placental vasculature. This pathological remodeling consists in increased serine palmitoyltransferase (SPT) activity and SM accrual in PE chorionic arteries, with concomitance impairment endothelial S1P signaling in the endothelium of these vessels. The increase of endothelial S1P phosphatase, lyase and S1PR2, and blunted S1PR1 expression support the onset of the pathological phenotype in chorionic arteries.

Plasma ceramide is increased and associated with proteinuria in women with pre-eclampsia and HELLP syndrome

OBJECTIVES

Ceramide is a sphingolipid with anti-angiogenic and pro-apoptotic properties that has shown to be increased in plasma of women with pre-eclampsia. We aimed to compare plasma and placental sphingolipid content among normotensive pregnant women and pre-eclamptic women with and without HELLP syndrome and we aimed to assess whether ceramide is related to hypertension and proteinuria in pre-eclampsia.

STUDY DESIGN

Case-control study. Participants were recruited from the Department of Obstetrics at the Academic Medical Center in Amsterdam, The Netherlands. In total 48 pregnant women were included: 24 with pre-eclampsia and 24 normotensive controls. Of the 24 pre-eclamptic women, 11 had HELLP syndrome.

MAIN OUTCOME MEASURES

Plasma and placental ceramide content and correlation with blood pressure and protein excretion in pre-eclampsia.

RESULTS

Total plasma, but not placental, ceramide was higher in pre-eclamptic women with HELLP syndrome (11200 95% CI 9531-12870 nmol/ml, n = 11) compared to pre-eclamptic women without HELLP (7413 95% CI 5928-8898 nmol/ml, n = 13, p < 0.001) and normotensive pregnant women (7404 95% CI 6695-8112 nmol/ml, n = 24, p < 0.001). Maternal circulating ceramide levels were strongly associated with proteinuria (r = 0.621, n = 24, p = 0.001) in pre-eclamptic women and inversely correlated with gestational age at delivery (r = 0.771, p < 0.01) in pre-eclamptic women with HELLP syndrome. Plasma ceramide was not correlated with blood pressure.

CONCLUSION

Plasma but not placental ceramide content is increased in women with pre-eclampsia and HELLP syndrome. The strong positive correlation with proteinuria and the inverse correlation with gestational age at delivery indicate that excess plasma ceramide may contribute to the pathophysiology of pre-eclampsia and HELLP.

Lipidomic profiles of maternal blood at the earlier stage of gestation and umbilical venous blood in response to supraphysiological hypercholesterolemia versus physiological hypercholesterolemia: An evidence of potential biomarkers and early intervention

BACKGROUND

To our knowledge, we lack a complete understanding of the lipidomes alterations caused by maternal supraphysiological hypercholesterolemia (MSPH) at the third trimester.

OBJECTIVES

The aim of this study was to investigate lipidomes alterations in maternal and umbilical venous (UV) serum and explore the association between these alterations and MSPH.

METHODS

We conducted a nest case-control study between maternal physiological hypercholesterolemia (MPH) and MSPH subjects during pregnancy. Lipidomic profiling of maternal serum at the first trimester of gestation and UV serum was performed by ultra-high-performance liquid chromatography system connected to a quadrupole time-of-light/mass spectrometer.

RESULTS

Several glycerophospholipids and sphingolipids (C18 sphingoid base) species were distinctly altered in maternal serum and/or UV serum with MSPH versus MPH. Glycerophospholipid metabolism, sphingolipid metabolism and propanoate metabolism were the main pathways that involved the most of discriminate metabolites. Higher HDL-c and phosphatidylcholine (16:0/0:0) (PC (16:0/0:0)) during pregnancy, higher PC (16:0/0:0) and lower cholesterol ester 20:4(8Z,11Z,14Z,17Z) (CE (20:4(8Z,11Z,14Z,17Z))) in the UV serum may be the risk factors for the increased placental circulation resistance. The total cholesterol levels of maternal serum both at the first trimester and at the third trimester were significantly correlated with some lipid species of UV serum.

CONCLUSION

This study clarifies the differential lipid profiles to distinguish MSPH from MPH and the pathway which is influenced under the condition of MSPH. Also, it provides a resource to look for potential therapeutic targets for MSPH.

Epitranscriptomic profiling in human placenta: N6-methyladenosine modification at the 5'-untranslated region is related to fetal growth and preeclampsia

Intracellular mRNA levels are not always proportional to their respective protein levels, especially in the placenta. This discrepancy may be attributed to various factors including post‐transcriptional regulation, such as mRNA methylation (N6‐methyladenosine: m⁶A). Here, we conducted a comprehensive m⁶A analysis of human placental tissue from neonates with various birth weights to clarify the involvement of m⁶A in placental biology. The augmented m⁶A levels at the 5′‐untranslated region (UTR) in mRNAs of small‐for‐date placenta samples were dominant compared to reduction of m⁶A levels, whereas a decrease in m⁶A in the vicinity of stop codons was common in heavy‐for‐date placenta samples. Notably, most of these genes showed similar expression levels between the different birth weight categories. In particular, preeclampsia placenta samples showed consistently upregulated SMPD1 protein levels and increased m⁶A at 5′‐UTR but did not show increased mRNA levels. Mutagenesis of adenosines at 5′‐UTR of SMPD1 mRNAs actually decreased protein levels in luciferase assay. Collectively, our findings suggest that m⁶A both at the 5′‐UTR and in the vicinity of stop codon in placental mRNA may play important roles in fetal growth and disease.

The vaginal metabolome and microbiota of cervical HPV-positive and HPV-negative women: a cross-sectional analysis

OBJECTIVE

Characterise the vaginal metabolome of cervical HPV-infected and uninfected women.

DESIGN

Cross-sectional.

SETTING

The Center for Health Behavior Research at the University of Maryland School of Public Health.

SAMPLE

Thirty-nine participants, 13 categorised as HPV-negative and 26 as HPV-positive (any genotype; HPV⁺ ), 14 of whom were positive with at least one high-risk HPV strain (hrHPV).

METHOD

Self-collected mid-vaginal swabs were profiled for bacterial composition by 16S rRNA gene amplicon sequencing, metabolites by both gas and liquid chromatography mass spectrometry, and 37 types of HPV DNA.

MAIN OUTCOME MEASURES

Metabolite abundances.

RESULTS

Vaginal microbiota clustered into Community State Type (CST) I (Lactobacillus crispatus-dominated), CST III (Lactobacillus iners-dominated), and CST IV (low-Lactobacillus, 'molecular-BV'). HPV⁺ women had higher biogenic amine and phospholipid concentrations compared with HPV^- women after adjustment for CST and cigarette smoking. Metabolomic profiles of HPV⁺ and HPV^- women differed in strata of CST. In CST III, there were higher concentrations of biogenic amines and glycogen-related metabolites in HPV⁺ women than in HPV^- women. In CST IV, there were lower concentrations of glutathione, glycogen, and phospholipid-related metabolites in HPV⁺ participants than in HPV^- participants. Across all CSTs, women with hrHPV strains had lower concentrations of amino acids, lipids, and peptides compared with women who had only low-risk HPV (lrHPV).

CONCLUSIONS

The vaginal metabolome of HPV⁺ women differed from HPV^- women in terms of several metabolites, including biogenic amines, glutathione, and lipid-related metabolites. If the temporal relation between increased levels of reduced glutathione and oxidised glutathione and HPV incidence/persistence is confirmed in future studies, anti-oxidant therapies may be considered as a non-surgical HPV control intervention.

TWEETABLE ABSTRACT

Metabolomics study: Vaginal microenvironment of HPV⁺ women may be informative for non-surgical interventions.

The role of dihydrosphingolipids in disease

Dihydrosphingolipids refer to sphingolipids early in the biosynthetic pathway that do not contain a C4-trans-double bond in the sphingoid backbone: 3-ketosphinganine (3-ketoSph), dihydrosphingosine (dhSph), dihydrosphingosine-1-phosphate (dhS1P) and dihydroceramide (dhCer). Recent advances in research related to sphingolipid biochemistry have shed light on the importance of sphingolipids in terms of cellular signalling in health and disease. However, dihydrosphingolipids have received less attention and research is lacking especially in terms of their molecular mechanisms of action. This is despite studies implicating them in the pathophysiology of disease, for example dhCer in predicting type 2 diabetes in obese individuals, dhS1P in cardiovascular diseases and dhSph in hepato-renal toxicity. This review gives a comprehensive summary of research in the last 10-15 years on the dihydrosphingolipids, 3-ketoSph, dhSph, dhS1P and dhCer, and their relevant roles in different diseases. It also highlights gaps in research that could be of future interest.

Maternal obesity leads to long-term altered levels of plasma ceramides in the offspring as revealed by a longitudinal lipidomic study in children

BACKGROUND/OBJECTIVES

Maternal obesity is associated with increased risk of obesity and other symptoms of the metabolic syndrome in the offspring. Nevertheless, the molecular mechanisms and cellular factors underlying this enhanced disease susceptibility remain to be determined. Here, we aimed at identifying changes in plasma lipids in offspring of obese mothers that might underpin, and serve as early biomarkers of, their enhanced metabolic disease risk.

SUBJECTS/METHODS

We performed a longitudinal lipidomic profiling in plasma samples from normal weight, overweight, and obese pregnant women and their children that participated in the Prenatal Omega-3 Fatty Acid Supplementation, Growth, and Development trial conducted in Mexico. At recruitment women were aged between 18 and 35 years and in week 18-22 of pregnancy. Blood samples were collected at term delivery by venipuncture from mothers and from the umbilical cord of their newborns and from the same infants at 4 years old under non-fasting conditions. Lipidomic profiling was done using ultra-performance liquid chromatography high-resolution mass spectrometry.

RESULTS

Analysis of the lipidomic data showed that overweight and obese mothers exhibited a significant reduction in the total abundance of ceramides (Cer) in plasma, mainly of Cer (d18:1/20:0), Cer (d18:1/22:0), Cer (d18:1/23:0), and Cer (d18:1/24:0), compared with mothers of normal body weight. This reduction was confirmed by the direct quantification of these and other ceramide species. Similar quantitative differences in the plasma concentration of Cer (d18:1/22:0), Cer (d18:1/23:0), and Cer (d18:1/24:0), were also found between 4-year-old children of overweight and obese mothers compared with children of mothers of normal body weight. Noteworthy, children exhibited equal daily amounts of energy and food intake independently of the BMI of their mothers.

CONCLUSIONS

Maternal obesity results in long-lasting changes in plasma ceramides in the offspring suggesting that these lipids might be used as early predictors of metabolic disease risk due to maternal obesity.

Role of dyslipidemia in preeclampsia-A review of lipidomic analysis of blood, placenta, syncytiotrophoblast microvesicles and umbilical cord artery from women with preeclampsia

Preeclampsia is a complex disorder and the pathogenesis of it is still not fully understood. The most commonly accepted theory of pathogenesis assumes that there occurs impaired trophoblastic invasion and failure in spiral artery remodeling. Nowadays, obesity becomes one of the most important, modifiable risk factors for the development of preeclampsia. Despite research into the condition, predicting which women with risk factors will develop preeclampsia remains problematic. Emerging evidence suggests that dysregulation of maternal and placental lipid metabolism are involved in the pathogenesis of the condition. Hence, researchers are focused on finding a lipid fingerprint, which contains information about the lipid composition and abundance of individual lipids by using new methods in the field of lipidomics. In this review we aimed to discuss the role of dyslipidemia in the pathogenesis of preeclampsia. In addition, on the basis of current research, we attempted to find a specific lipid profile of different tissues in women with preeclampsia.