Spontaneous miscarriage in first trimester pregnancy is associated with altered urinary metabolite profile

Carnitine traffic and human fertility

Carnitine is a vital molecule in human metabolism, prominently involved in fatty acid β-oxidation within mitochondria. Predominantly sourced from dietary intake, carnitine also derives from endogenous synthesis. This review delves into the complex network of carnitine transport and distribution, emphasizing its pivotal role in human fertility. Together with its role in fatty acid oxidation, carnitine modulates the acety-CoA/CoA ratio, influencing carbohydrate metabolism, lipid biosynthesis, and gene expression. The intricate regulation of carnitine homeostasis involves a network of membrane transporters, notably OCTN2, which is central in its absorption, reabsorption, and distribution. OCTN2 dysfunction, results in Primary Carnitine Deficiency (PCD), characterized by systemic carnitine depletion and severe clinical manifestations, including fertility issues. In the male reproductive system, carnitine is crucial for sperm maturation and motility. In the female reproductive system, carnitine supports mitochondrial function necessary for oocyte quality, folliculogenesis, and embryonic development. Indeed, deficiencies in carnitine or its transporters have been linked to asthenozoospermia, reduced sperm quality, and suboptimal fertility outcomes in couples. Moreover, the antioxidant properties of carnitine protect spermatozoa from oxidative stress and help in managing conditions like polycystic ovary syndrome (PCOS) and endometriosis, enhancing sperm viability and fertilization potential of oocytes. This review summarizes the key role of membrane transporters in guaranteeing carnitine homeostasis with a special focus on the implications in fertility and possible treatments of infertility and other related disorders.

Untargeted Metabolomic Biomarker Discovery for the Detection of Ectopic Pregnancy

Ectopic pregnancy (EP) is the leading cause of maternal morbidity and mortality in the first trimester. Using an untargeted metabolomic approach, we sought to identify putative plasma biomarkers using tandem liquid chromatography-mass spectrometry for the detection of tubal EP. This case-control study included the prospective recruitment of 50 tubal EP cases and 50 early intrauterine pregnancy controls. To avoid over-fitting, logistic regression models were developed in a randomly selected discovery group (30 cases vs. 30 controls) and validated in the test group (20 cases vs. 20 controls). In total, 585 mass spectral features were detected, of which 221 molecular features were significantly altered in EP plasma (p < 0.05). Molecular networking and metabolite identification was employed using the Global Natural Products Social Molecular Networking (GNPS) database, which identified 97 metabolites at a high confidence level. Top significant metabolites include subclasses of sphingolipids, carnitines, glycerophosphocholines, and tryptophan metabolism. The top regression model, consisting of D-erythro-sphingosine and oleoyl-carnitine, was validated in a test group and achieved an area under receiving operating curve (AUC) (95% CI) = 0.962 (0.910-1) with a sensitivity of 100% and specificity of 95.9%. Metabolite alterations indicate alterations related to inflammation and abnormal placentation in EP. The validation of these metabolite biomarkers in the future could potentially result in improved early diagnosis.

Current Ovulation and Luteal Phase Tracking Methods and Technologies for Fertility and Family Planning: A Review

Ovulation is critical for both conception and overall health, but many people who may ovulate are not tracking ovulation or any other part of their menstrual cycle. Failure to track ovulation, especially in those trying to conceive, can lead to fertility challenges due to absent ovulation, mistiming intercourse, or an undetected luteal phase defect. Ovulatory disorders and mistiming intercourse are both primary causes of infertility, and tracking ovulation is shown to decrease the average time to conception. While there are many tracking methods and apps available, the majority are predictive apps or ovulation predictor kits and do not test or track both successful ovulation and the health of the luteal phase, leading to missing information that could contribute to diagnosis or successful conception. Here, we review why ovulation tracking and a healthy luteal phase are important for those trying to conceive. We present currently available ovulation tracking methods that detect both ovulation and the luteal phase, including cervical mucus, urinary hormone testing, and basal body temperature, and discuss the use, advantages, and disadvantages of each. Finally, we consider the role of digital applications and tracking technologies in ovulation tracking.

The metabolomic profile of endometrial receptivity in recurrent miscarriage

BACKGROUND

Endometrial receptivity has been the focus of continuous research for over eight decades; however, current clinical practice lacks an accurate test of endometrial receptivity to allow the prediction of successful pregnancy. We aimed to characterize the endometrial metabolomic profiles of women who suffered recurrent miscarriage using discovery metabolomics and to set the foundation for the development of an endometrial receptivity test.

METHODS

This was a prospective multicenter cohort study led by the Tommy's National Centre for Miscarriage Research in Birmingham. Endometrial biopsies were obtained during the window of implantation from 24 women aged 18-35 years, who were not pregnant and regularly menstruating, diagnosed with unexplained recurrent miscarriage. The metabolite composition and relative concentrations of samples were analyzed applying ultra-high performance liquid chromatography-mass spectrometry to investigate water-soluble and lipid metabolites.

RESULTS

Various metabolic perturbations are associated with observation of increased numbers of miscarriages. They relate to fatty acid metabolism including increased lipolysis and decreased medium chain fatty acid beta-oxidation, poorer mitochondrial health, and redox-active co-factors which are present at higher oxidative levels. Other metabolic perturbations are associated with observation of live birth following miscarriages. They relate to perturbed cholesterol-cholesterol sulphate metabolism, fatty acid metabolism including increased diacylglyceride lipolysis and decreased medium chain fatty acid beta-oxidation, and improved mitochondrial health.

CONCLUSIONS

The present endometrial metabolomics discovery studies have implicated a small number of metabolic pathways and biological functions which are biologically important in miscarriage mechanisms.

Application of SERS in In-Vitro Biomedical Detection

Surface-enhanced Raman scattering (SERS), as a rapid and nondestructive biological detection method, holds great promise for clinical on spot and early diagnosis. In order to address the challenging demands of on spot detection of biomedical samples, a variety of strategies has been developed. These strategies include substrate structural and component engineering, data processing techniques, as well as combination with other analytical methods. This report summarizes the recent SERS developments for biomedical detection, and their promising applications in cancer detection, virus or bacterial infection detection, miscarriage spotting, neurological disease screening et al. The first part discusses the frequently used SERS substrate component and structures, the second part reports on the detection strategies for nucleic acids, proteins, bacteria, and virus, the third part summarizes their promising applications in clinical detection in a variety of illnesses, and the forth part reports on recent development of SERS in combination with other analytical techniques. The special merits, challenges, and perspectives are discussed in both introduction and conclusion sections.

Metabolomic markers of biological fluid in women with reproductive failure: a systematic review of current literatures

Understanding metabolic changes in reproductive failure, including early miscarriage (EM), recurrent miscarriage (RM) and repeated implantation failure (RIF), may be beneficial to understand the pathophysiology, thus improving pregnancy outcomes. Nine metabolomic profiling studies in women with reproductive failures (4 for EM, 3 for RM and 2 for RIF) were included for systematic review. In total 78, 75 and 25 significant metabolites were identified and 40, 40 and 34 metabolic pathways were enriched in EM, RM and RIF, respectively. Among them, 7 and 11 metabolites, and 28 and 28 pathways were shared between EM and RM and between RM and RIF, respectively. Notably, histidine metabolism has the highest impact in EM; phenylalanine, tyrosine and tryptophan biosynthesis. Ubiquinone and other terpenoid-quinone biosynthesis metabolism have the highest impact factor in RM; alanine, aspartate and glutamate metabolism have the highest impact factor in RIF. This study not only summarized the common and distinct metabolites and metabolic pathways in different reproductive failures but also summarized limitations of the study designs and methodologies. Hence, further investigations and validations of these metabolites are still urgently needed to understand the underlying metabolic mechanism for the development and treatment of reproductive failures.

Candidate Circulating Biomarkers of Spontaneous Miscarriage After IVF-ET Identified via Coupling Machine Learning and Serum Lipidomics Profiling

Spontaneous miscarriage is a common pregnancy complication. Multiple etiologies have been proposed such as genetic aberrations, endocrinology disorder, and immunologic derangement; however, the relevance of circulating lipidomes to the specific condition remains unclear. In the present study, lipidomics profiling was examined on serum of women with spontaneous miscarriage after in vitro fertilization and embryo transfer (IVF-ET). Screening and analysis of differential lipid levels were conducted using a machine learning approach to verify the stability and validity of potential serum biomarkers. Seven lipid species presented significant differences between the abortion and term birth patients, including three types of sphingomyelins (SMs), two types of diglycerides (DGs), one phosphatidylcholine (PC), and one lysophosphatidylethanolamine (LPE). All the SMs presented with a fold change of > 1, while both the PC and LPE had a fold change of < 1. The DG containing two saturated fatty acyl chains was decreased, but that containing two unsaturated fatty acyl chains was increased in the miscarriage group compared to the control group. This study reveals the relevance of lipid profiles to spontaneous abortion after IVF-ET, providing potential biomarkers and therapeutic targets for the specific clinical scenario.

Multiplex Surface-Enhanced Raman Scattering Identification and Quantification of Urine Metabolites in Patient Samples within 30 min

Successful translation of laboratory-based surface-enhanced Raman scattering (SERS) platforms to clinical applications requires multiplex and ultratrace detection of small biomarker molecules from a complex biofluid. However, these biomarker molecules generally exhibit low Raman scattering cross sections and do not possess specific affinity to plasmonic nanoparticle surfaces, significantly increasing the challenge of detecting them at low concentrations. Herein, we demonstrate a "confine-and-capture" approach for multiplex detection of two families of urine metabolites correlated with miscarriage risks, 5β-pregnane-3α,20α-diol-3α-glucuronide and tetrahydrocortisone. To enhance SERS signals by 10¹²-fold, we use specific nanoscale surface chemistry for targeted metabolite capture from a complex urine matrix prior to confining them on a superhydrophobic SERS platform. We then apply chemometrics, including principal component analysis and partial least-squares regression, to convert molecular fingerprint information into quantifiable readouts. The whole screening procedure requires only 30 min, including urine pretreatment, sample drying on the SERS platform, SERS measurements, and chemometric analyses. These readouts correlate well with the pregnancy outcomes in a case-control study of 40 patients presenting threatened miscarriage symptoms.

Exosomes-Associated DNA-New Marker in Pregnancy Complications?

Despite a large number of studies, the etiology of pregnancy complications remains unknown. The involvement of cell-free DNA or fetal cell-free DNA in the pathogenesis of pregnancy complications is currently being hypothesized. Cell-free DNA occurs in different forms-free; part of neutrophil extracellular traps; or as recently discovered, carried by extracellular vesicles. Cell-free DNA is believed to activate an inflammatory pathway, which could possibly cause pregnancy complications. It could be hypothesized that DNA in its free form could be easily degraded by nucleases to prevent the inflammatory activation. However, recently, there has been a growing interest in the role of exosomes, potential protectors of cell-free DNA, in pregnancy complications. Most of the interest from recent years is directed towards the micro RNA carried by exosomes. However, exosome-associated DNA in relation to pregnancy complications has not been truly studied yet. DNA, as an important cargo of exosomes, has been so far studied mostly in cancer research. This review collects all the known information on the topic of not only exosome-associated DNA but also some information on vesicles-associated DNA and the studies regarding the role of exosomes in pregnancy complications from recent years. It also suggests possible analysis of exosome-associated DNA in pregnancy from plasma and emphasizes the importance of such analysis for future investigations of pregnancy complications. A major obstacle to the advancement in this field is the proper uniformed technique for exosomes isolation. Similarly, the sensitivity of methods analyzing a small fraction of DNA, potentially fetal DNA, carried by exosomes is variable.

Metabolomic Profiling of Plasma Samples from Women with Recurrent Spontaneous Abortion

Background

Gas chromatography coupled with mass spectrometry (GC-MS) and liquid chromatography coupled with mass spectrometry (LC-MS) metabolomics have been deployed to detect novel differential metabolites in cases with recurrent spontaneous abortion (RSA).

Material/Methods

Fifty patients who had recurrent spontaneous abortions (RSAs) and 51 control patients (age, gestational age, and body mass index (BMI) match) were enrolled in this study. Untargeted GC-MS and targeted LC-MS were combined to discover and validate the different metabolomic profiles between groups. Score plots of orthogonal partial least-squares discriminant analysis (OPLS-DA) clearly separated the RSA group from the control group. The variable importance in projection (VIP) generated in OPLS-DA processing represented the contribution to the discrimination of each metabolite ion between groups. Variables with a VIP >1 and P<0.05 were considered to be different variables. We also used MetaboAnalyst 3.0 to analyze the pathway impact of potential metabolite biomarkers.

Results

Fifty-four metabolites were significantly different between the two groups, as indicated by a VIP >1 and P<0.05. The metabolic pathways involving glycine, serine, threonine (P=0.00529, impact=0.26), beta-alanine (P=0.0284, impact=0.27), and phenylalanine metabolism (P=0.0217, impact=0.17), along with the tricarboxylic acid (TCA) cycle (P=0.0113, impact=0.19) and the glycolysis pathway (P=0.037, impact=0.1) are obviously related to RSA. Verification by LC-MS showed that the concentration of lactic acid in RSA was higher than that in the control group (P<0.05), while the concentration of 5-methoxytryptamine was significantly lower in the RSA group (P<0.05).

Conclusions

In our study, untargeted GC-MS was used to detect disturbance of metabolism occurs in RSA and targeted LC-MS further was used to show that plasma concentrations of two metabolites (lactic acid and 5-methoxytryptamine) were different in the RSA compared to the control group.