Metabolomic analysis for first-trimester trisomy 18 detection

Short-Chain Fatty Acid Reference Ranges in Pregnant Women from a Mediterranean Region of Northern Spain: ECLIPSES Study

Maternal short-chain fatty acids (SCFAs) play a critical role in fetal development and metabolic programming. However, an important gap in the analysis of such relationships is the lack of reference values in pregnant women. Therefore, we establish serum SCFA percentile reference ranges both early and later in pregnancy in a population from a Mediterranean region of Northern Spain. A population-based follow-up study involving 455 healthy pregnant women (mean age 30.6 ± 5.0 years) from the ECLIPSES study is conducted. Sociodemographic, obstetric, anthropometric, lifestyle, dietary variables and blood samples were collected in the first and third trimesters. Serum SCFA concentrations were measured by LC-MS/MS. The 2.5/97.5 percentiles of the reference interval for serum acetic, propionic, isobutyric, and butyric acids were 16.4/103.8 µmol/L, 2.1/5.8 µmol/L, 0.16/1.01 µmol/L and 0.32/1.67 µmol/L in the first trimester of pregnancy, respectively. In the third trimester, butyrate levels increased with most of the maternal factors and categories studied, while acetic acid and isobutyric acid decreased only in some maternal categories. Propionic acid was not affected by maternal factors. Reference ranges did not vary with maternal age, body weight, social class or diet, but decreased with smoking, high physical activity, low BMI and primiparity. This study establishes for the first-time SCFAs reference ranges in serum for women in our region in both early and late pregnancy. This information can be useful to monitor pregnancy follow-up and detect risk values.

LC-MS Analysis Revealed the Significantly Different Metabolic Profiles in Spent Culture Media of Human Embryos with Distinct Morphology, Karyotype and Implantation Outcomes

In this study we evaluated possible differences in metabolomic profiles of spent embryo culture media (SECM) of human embryos with distinct morphology, karyotype, and implantation outcomes. A total of 153 samples from embryos of patients undergoing in vitro fertilization (IVF) programs were collected and analyzed by HPLC-MS. Metabolomic profiling and statistical analysis revealed clear clustering of day five SECM from embryos with different morphological classes and karyotype. Profiling of day five SECM from embryos with different implantation outcomes showed 241 significantly changed molecular ions in SECM of successfully implanted embryos. Separate analysis of paired SECM samples on days three and five revealed 46 and 29 molecular signatures respectively, significantly differing in culture media of embryos with a successful outcome. Pathway enrichment analysis suggests certain amino acids, vitamins, and lipid metabolic pathways to be crucial for embryo implantation. Differences between embryos with distinct implantation potential are detectable on the third and fifth day of cultivation that may allow the application of culture medium analysis in different transfer protocols for both fresh and cryopreserved embryos. A combination of traditional morphological criteria with metabolic profiling of SECM may increase implantation rates in assisted reproductive technology programs as well as improve our knowledge of the human embryo metabolism in the early stages of development.

Metabolomics in Prenatal Medicine: A Review

Pregnancy is a complicated and insidious state with various aspects to consider, including the well-being of the mother and child. Developing better non-invasive tests that cover a broader range of disorders with lower false-positive rates is a fundamental necessity in the prenatal medicine field, and, in this sense, the application of metabolomics could be extremely useful. Metabolomics measures and analyses the products of cellular biochemistry. As a biomarker discovery tool, the integrated holistic approach of metabolomics can yield new diagnostic or therapeutic approaches. In this review, we identify and summarize prenatal metabolomics studies and identify themes and controversies. We conducted a comprehensive search of PubMed and Google Scholar for all publications through January 2020 using combinations of the following keywords: nuclear magnetic resonance, mass spectrometry, metabolic profiling, prenatal diagnosis, pregnancy, chromosomal or aneuploidy, pre-eclampsia, fetal growth restriction, pre-term labor, and congenital defect. Metabolite detection with high throughput systems aided by advanced bioinformatics and network analysis allowed for the identification of new potential prenatal biomarkers and therapeutic targets. We took into consideration the scientific papers issued between the years 2000-2020, thus observing that the larger number of them were mainly published in the last 10 years. Initial small metabolomics studies in perinatology suggest that previously unidentified biochemical pathways and predictive biomarkers may be clinically useful. Although the scientific community is considering metabolomics with increasing attention for the study of prenatal medicine as well, more in-depth studies would be useful in order to advance toward the clinic world as the obtained results appear to be still preliminary. Employing metabolomics approaches to understand fetal and perinatal pathophysiology requires further research with larger sample sizes and rigorous testing of pilot studies using various omics and traditional hypothesis-driven experimental approaches.

Creatine Metabolism in Female Reproduction, Pregnancy and Newborn Health

Creatine metabolism is an important component of cellular energy homeostasis. Via the creatine kinase circuit, creatine derived from our diet or synthesized endogenously provides spatial and temporal maintenance of intracellular adenosine triphosphate (ATP) production; this is particularly important for cells with high or fluctuating energy demands. The use of this circuit by tissues within the female reproductive system, as well as the placenta and the developing fetus during pregnancy is apparent throughout the literature, with some studies linking perturbations in creatine metabolism to reduced fertility and poor pregnancy outcomes. Maternal dietary creatine supplementation during pregnancy as a safeguard against hypoxia-induced perinatal injury, particularly that of the brain, has also been widely studied in pre-clinical in vitro and small animal models. However, there is still no consensus on whether creatine is essential for successful reproduction. This review consolidates the available literature on creatine metabolism in female reproduction, pregnancy and the early neonatal period. Creatine metabolism is discussed in relation to cellular bioenergetics and de novo synthesis, as well as the potential to use dietary creatine in a reproductive setting. We highlight the apparent knowledge gaps and the research “road forward” to understand, and then utilize, creatine to improve reproductive health and perinatal outcomes.

Metabolomic identification of novel diagnostic biomarkers in ectopic pregnancy

INTRODUCTION

Ectopic pregnancy (EP) is a potentially life-threatening condition and early diagnosis still remains a challenge, causing a delay in management leading to tubal rupture.

OBJECTIVES

To identify putative plasma biomarkers for the detection of tubal EP and elucidate altered biochemical pathways in EP compared to intrauterine pregnancies.

METHODS

This case-control study included prospective recruitment of 39 tubal EP cases and 89 early intrauterine pregnancy controls. Plasma samples were biochemically profiled using proton nuclear magnetic resonance spectroscopy (¹H NMR). To avoid over-fitting, datasets were randomly divided into a discovery group (26 cases vs 60 controls) and a test group (13 cases and 29 controls). Logistic regression models were developed in the discovery group and validated in the independent test group. Area under the receiver operating characteristics curve (AUC), 95% confidence interval (CI), sensitivity, and specificity values were calculated.

RESULTS

In total 13 of 43 (30.3%) metabolite concentrations were significantly altered in EP plasma (p < 0.05). Metabolomic profiling yielded significant separation between EP and controls (p < 0.05). Independent validation of a two-metabolite model consisting of lactate and acetate, achieved an AUC (95% CI) = 0.935 (0.843-1.000) with a sensitivity of 92.3% and specificity of 96.6%. The second metabolite model (D-glucose, pyruvate, acetoacetate) performed well with an AUC (95% CI) = 0.822 (0.657-0.988) and a sensitivity of 84.6% and specificity of 86.2%.

CONCLUSION

We report novel metabolomic biomarkers with a high accuracy for the detection of EP. Accurate biomarkers could potentially result in improved early diagnosis of tubal EP cases.

Trace Amines and Their Receptors

Trace amines are endogenous compounds classically regarded as comprising β-phenylethyalmine, p-tyramine, tryptamine, p-octopamine, and some of their metabolites. They are also abundant in common foodstuffs and can be produced and degraded by the constitutive microbiota. The ability to use trace amines has arisen at least twice during evolution, with distinct receptor families present in invertebrates and vertebrates. The term "trace amine" was coined to reflect the low tissue levels in mammals; however, invertebrates have relatively high levels where they function like mammalian adrenergic systems, involved in "fight-or-flight" responses. Vertebrates express a family of receptors termed trace amine-associated receptors (TAARs). Humans possess six functional isoforms (TAAR1, TAAR2, TAAR5, TAAR6, TAAR8, and TAAR9), whereas some fish species express over 100. With the exception of TAAR1, TAARs are expressed in olfactory epithelium neurons, where they detect diverse ethological signals including predators, spoiled food, migratory cues, and pheromones. Outside the olfactory system, TAAR1 is the most thoroughly studied and has both central and peripheral roles. In the brain, TAAR1 acts as a rheostat of dopaminergic, glutamatergic, and serotonergic neurotransmission and has been identified as a novel therapeutic target for schizophrenia, depression, and addiction. In the periphery, TAAR1 regulates nutrient-induced hormone secretion, suggesting its potential as a novel therapeutic target for diabetes and obesity. TAAR1 may also regulate immune responses by regulating leukocyte differentiation and activation. This article provides a comprehensive review of the current state of knowledge of the evolution, physiologic functions, pharmacology, molecular mechanisms, and therapeutic potential of trace amines and their receptors in vertebrates and invertebrates.

Untargeted metabolomics: an overview of its usefulness and future potential in prenatal diagnosis

INTRODUCTION

Metabolomics opens up new avenues for biomarker discovery in different branches of medicine, including perinatology. Chromosomal aberration, preterm delivery (PTD), congenital heart defects, spina bifida, chorioamnionitis, and low birth weight are the main perinatal pathologies. Investigations using untargeted metabolomics have found the candidate metabolites for diagnostic biomarkers. Areas covered: This review describes areas of prenatal diagnosis in which untargeted metabolomics has been used. Data on the disease, type of sample, techniques used, number of samples used in the study, and metabolites obtained including the sign of their regulation are summarized. Expert commentary: Untargeted metabolomics is a powerful tool which can shed a new light on prenatal diagnostics. It helps to discover affected metabolic pathways what may help to reveal disease pathogenesis and propose potential biomarkers. Among others, glycerol and 2- and 3-hydroxybutyrate were proposed as markers of chromosomal aberration. Serum metabolic signature of PTD was characterized by increased lipids and decreased levels of hypoxanthine, tryptophane, and pyroglutamic acid. Lower level lipids and vitamin D3 metabolites together with increased bilirubin level in maternal serum were associated with macrosomia. However, to give a real value to those assays and allow their clinical application multicenter, large cohort validation studies are necessary.

Impact of fetal chromosomal disorders on maternal blood metabolome: toward new biomarkers?

OBJECTIVE

This study aimed at determining the relationship between fetal chromosomal disorders (CDs), including trisomy 21 (T21), and on first- and second-trimester maternal blood plasma, to identify the time-course metabolic adaptations to the conditions and the possible new plasma biomarkers. Furthermore, a definition of a joint circulatory (plasma) and excretory (urine) metabolic description of second-trimester CDs was sought.

STUDY DESIGN

Plasma was obtained for 119 pregnant women: 74 controls and 45 CD cases, including 22 T21 cases. Plasma and lipid extracts (for T21 only) were analyzed by nuclear magnetic resonance spectroscopy, and data were handled by variable selection and multivariate analysis. Correlation analysis was used on a concatenated plasma/urine matrix descriptive of second-trimester CD, based on previously obtained urine data.

RESULTS

CD cases were accompanied by enhanced lipid β-oxidation (increased ketone bodies) and underutilization of glucose, pyruvate, and citrate. Lower circulating high-density lipoprotein levels were noted, along with changes in the proline and methanol in the first trimester, and also the urea, creatinine, acetate, and low-density lipoprotein plus very low-density lipoprotein in the second trimester and the different urea and creatinine levels, suggesting fetal renal dysfunction. In terms of plasma composition, T21 cases were indistinguishable from other CDs in the first trimester, whereas in the second trimester, increased methanol and albumin may be T21 specific. Furthermore, first-trimester lipid extracts of T21 showed decreased levels of 18:2 fatty acids, whereas in the second trimester, lower levels of 20:4 and 22:6 fatty acids were noted, possibly indicative of inflammation mechanisms. In both trimesters, high classification rates for CDs (88-89%) and T21 (85-92%) generally relied on variable selection of nuclear magnetic resonance data. Plasma/urine correlations confirmed most metabolic deviations and unveiled possible new ones regarding low-density lipoprotein plus very low-density lipoprotein, sugar, and gut-microflora metabolisms.

CONCLUSION

This work partially confirmed previously reported data on first-trimester T21 and provided additional information on time-course metabolic changes accompanying CD and T21, in particular regarding plasma lipid composition. These results demonstrate the potential of plasma metabolomics in monitoring and characterizing CD cases; however, validation in larger cohorts is desirable.

Advances in revealing the molecular targets downstream of oxidative stress-induced proapoptotic kinase signaling in diabetic embryopathy

Preexisting maternal diabetes is a high-risk factor of diabetic embryopathy, such as neural tube defects and congenital heart defects. Maternal diabetes significantly increases the production of reactive oxygen species, resulting in oxidative stress and diabetic embryopathy. Multiple cellular and metabolic factors contribute to these processes. Forkhead box O (FoxO)-3a has been demonstrated as a key transcription factor in the signaling transduction pathways responsible for maternal diabetes-induced birth defects. Apoptosis signal-regulating kinase 1 (ASK1) activated by oxidative stress stimulates nuclear translocation of FoxO3a, resulting in the overexpression of tumor necrosis factor receptor 1-associated death domain protein, which, in turn, leads to caspase-8 activation and apoptosis. Maternal diabetes-activated c-Jun N-terminal kinase (JNK)-1/2, downstream effectors of ASK1, can be blocked by superoxide dismutase-1 overexpression, suggesting that oxidative stress is responsible for JNK1/2 signaling activation. Deletion of JNK1/2 significantly suppressed the activity of FoxO3a. These observations indicate that maternal diabetes-induced oxidative stress stimulates the activation of ASK1, JNK1/2, FoxO3a, tumor necrosis factor receptor 1-associated death domain protein, caspase-8 cleavage, and finally, apoptosis and diabetic embryopathy.

Curcumin ameliorates high glucose-induced neural tube defects by suppressing cellular stress and apoptosis

OBJECTIVE

Curcumin is a naturally occurring polyphenol present in the roots of the Curcuma longa plant (turmeric), which possesses antioxidant, antitumorigenic, and antiinflammatory properties. Here, we test whether curcumin treatment reduces high glucose-induced neural tube defects (NTDs), and if this occurs via blocking cellular stress and caspase activation.

STUDY DESIGN

Embryonic day 8.5 mouse embryos were collected for use in whole-embryo culture under normal (100 mg/dL) or high (300 mg/dL) glucose conditions, with or without curcumin treatment. After 24 hours in culture, protein levels of oxidative stress makers, nitrosative stress makers, endoplasmic reticulum (ER) stress makers, cleaved caspase 3 and 8, and the level of lipid peroxides were determined in the embryos. After 36 hours in culture, embryos were examined for evidence of NTD formation.

RESULTS

Although 10 μmol/L of curcumin did not significantly reduce the rate of NTDs caused by high glucose, 20 μmol/L of curcumin significantly ameliorated high glucose-induced NTD formation. Curcumin suppressed oxidative stress in embryos cultured under high glucose conditions. Treatment reduced the levels of the lipid peroxidation marker, 4-hydroxynonenal, nitrotyrosine-modified protein, and lipid peroxides. Curcumin also blocked ER stress by inhibiting phosphorylated protein kinase RNA-like ER kinase, phosphorylated inositol-requiring protein-1α (p-IRE1α), phosphorylated eukaryotic initiation factor 2α (p-eIF2α), C/EBP-homologous protein, binding immunoglobulin protein, and x-box binding protein 1 messenger RNA splicing. Additionally, curcumin abolished caspase 3 and caspase 8 cleavage in embryos cultured under high glucose conditions.

CONCLUSION

Curcumin reduces high glucose-induced NTD formation by blocking cellular stress and caspase activation, suggesting that curcumin supplements could reduce the negative effects of diabetes on the embryo. Further investigation will be needed to determine if the experimental findings can translate into clinical settings.

Oxidative stress is responsible for maternal diabetes-impaired transforming growth factor beta signaling in the developing mouse heart

OBJECTIVE

Oxidative stress plays a causal role in diabetic embryopathy. Maternal diabetes induces heart defects and impaired transforming growth factor beta (TGFβ) signaling, which is essential for cardiogenesis. We hypothesize that mitigating oxidative stress through superoxide dismutase 1 (SOD1) overexpression in transgenic (Tg) mice reverses maternal hyperglycemia-impaired TGFβ signaling and its downstream effectors.

STUDY DESIGN

Day 12.5 embryonic hearts from wild-type (WT) and SOD1 overexpressing embryos of nondiabetic (ND) and diabetic mellitus (DM) dams were used for the detection of oxidative stress markers: 4-hydroxynonenal (4-HNE) and malondlaldehyde (MDA), and TGFβ1, 2, and 3, phosphor (p)-TGFβ receptor II (TβRII), p-phosphorylated mothers against decapentaplegic (Smad)2, and p-Smad3. The expression of 3 TGFβ-responsive genes was also assessed. Day 11.5 embryonic hearts were explanted and cultured ex vivo, with or without treatments of a SOD1 mimetic (Tempol; Enzo Life Science, Farmingdale, NY) or a TGFβ recombinant protein for the detection of TGFβ signaling intermediates.

RESULTS

Levels of 4-HNE and MDA were significantly increased by maternal diabetes, and SOD1 overexpression blocked the increase of these 2 oxidative stress markers. Maternal diabetes suppresses the TGFβ signaling pathway by down-regulating TGFβ1 and TGFβ3 expression. Consequently, phosphorylation of TβRII, Smad2, and Smad3, downstream effectors of TGFβ, and expression of 3 TGFβ-responsive genes were reduced by maternal diabetes, and these reductions were prevented by SOD1 overexpression. Treatment with Tempol or TGFβ recombinant protein restored high-glucose-suppressed TGFβ signaling intermediates and responsive gene expression.

CONCLUSION

Oxidative stress mediates the inhibitory effect of hyperglycemia in the developing heart. Antioxidants, TGFβ recombinant proteins, or TGFβ agonists may have potential therapeutic values in the prevention of heart defects in diabetic pregnancies.

Metabolomic profile of amniotic fluid to evaluate lung maturity: the diaphragmatic hernia lamb model

Background

Tracheal occlusion (TO) stimulates lung growth in fetuses affected with congenital diaphragmatic hernia (CDH) although the processes involved in lung maturation still remain unknown. The objective of this study was to evaluate the metabolomic profile of amniotic fluid (AF) following TO in fetal lamb model in order to obtain an indirect view of mechanisms involved in pulmonary reversal hypoplasia and biochemical maturity in response to fetal TO.

Methods

Liquid Chromatography Mass Spectrometry was performed on lamb AF samples at: age I (70 days’ gestation); age II (102 days’ gestation); age III (136 days’ gestation). CDH was induced at age I and TO at age II.

Results

Betaine, choline, creatinine were found significantly increased during gestation in the control group. The CDH group showed choline (p =0.007) and creatinine (p =0.004) decreases during pregnancy. In the TO group choline and creatinine profiles were restored.

Conclusions

Alveolar tissue and fetal global growth ameliorated after TO. Metabolomics provided useful information on biochemical details during lung maturation. Metabolomic profiling would help to identify the best time to perform TO, in order to increase survival of CDH affected patients.

Potential first trimester metabolomic biomarkers of abnormal birth weight in healthy pregnancies

OBJECTIVE

Macrosomia and low birth weight (LBW) can be associated with pregnancy complications and may affect the long-term health of the child. The aim of this study was to evaluate the metabolomic serum profiles of healthy pregnant women to identify early biomarkers of macrosomia and LBW and to understand mechanisms leading to abnormal fetal growth not related to mother's body mass index or presence of gestational diabetes.

METHOD

Serum samples from 770 women were collected between the 12th and 14th gestational week. Delivery samples were divided into three groups according to the infant birth weight as follows: low, <2500 g; normal, 2500-4000 g; and high >4000 g. Samples from women with any complications of pregnancy were excluded. Serum fingerprinting was performed by LC-QTOF-MS.

RESULTS

Lower levels of phospholipids, lysophospholipids, and monoacylglycerols; low vitamin D3 metabolites; and increased bilirubin level were associated with macrosomia. Because most changes involved lipids, as a concept of validation, adipocyte fatty acid-binding protein (A-FABP) levels were measured and found correlated with the studied lipids and birth weight.

CONCLUSION

Serum fingerprinting in early pregnancy can predict the risk of macrosomia. Serum levels of A-FABP and several lipids are promising prognostic markers for macrosomia in healthy pregnancies.