Myo-inositol alters the effects of glucose, leptin and insulin on placental palmitic acid and oleic acid metabolism

Well-regulated placental palmitic acid (PA) and oleic acid (OA) metabolism is vital for optimal placental function and fetal development, but dysregulation occurs with gestational diabetes (GDM). We hypothesized that such dysregulation might arise from increased maternofetal glucose, leptin or insulin concentrations present in GDM, and that dysregulated PA and OA lipid metabolism could be moderated by myo-inositol, a natural polyol and potential GDM intervention. Placental explants from 21 women were incubated with stable isotope-labelled 13 C-PA or 13 C-OA for 48 h. Explants were treated with glucose (5, 10 mm) or leptin (13 nm) or insulin (150 nm) in combination with myo-inositol (0.3, 30, 60 μm). Forty-seven 13 C-PA lipids and 37 13 C-OA lipids were measured by liquid chromatography-mass spectrometry (LCMS). Compared with controls (5 mm glucose), glucose (10 mm) increased 19 13 C-OA lipids and nine 13 C-PA lipids, but decreased 13 C-OA phosphatidylethanolamine 38:5 and 13 C-PA phosphatidylethanolamine 36:4. The effects of leptin and insulin were less prominent than glucose, with leptin increasing 13 C-OA acylcarnitine 18:1, and insulin increasing four 13 C-PA triacylglycerides. Most glucose, leptin and insulin-induced alterations in lipids were attenuated by co-incubation with myo-inositol (30 or 60 μm), with attenuation also occurring in all subgroups stratified by GDM status and fetal sex. However, glucose-induced increases in acylcarnitine were not attenuated by myo-inositol and were even exaggerated in some instances. Myo-inositol therefore appears to generally act as a moderator, suppressing the perturbation of lipid metabolic processes by glucose, leptin and insulin in placenta in vitro. Whether myo-inositol protects the fetus and pregnancy from unfavourable outcomes requires further research. KEY POINTS: Incubation of placental explants with additional glucose, or to a lesser extent insulin or leptin, alters the placental production of 13 C-lipids from 13 C-palmitic acid (PA) and 13 C-oleic acid (OA) in vitro compared with untreated controls from the same placenta. Co-incubation with myo-inositol attenuated most alterations induced by glucose, insulin or leptin in 13 C-lipids, but did not affect alterations in 13 C-acylcarnitines. Alterations induced by glucose and leptin in 13 C-PA triacylglycerides and 13 C-PA phospholipids were influenced by fetal sex and gestational diabetes status, but were all still attenuated by myo-inositol co-incubation. Insulin differently affected 13 C-PA triacylglycerides and 13 C-PA phospholipids depending on fetal sex, with alterations also attenuated by myo-inositol co-incubation.

The effect of maternal obesity and lipid profile on first-trimester serum progesterone levels

BACKGROUND

Prepregnancy overweight increases the risk of adverse perinatal outcomes. Maternal lipid profile plays a key role in the production of pregnancy hormones. The influence that obesity has on the specific mechanisms that may be involved and the potential associations with abnormal conditions in pregnancy are still poorly understood.

OBJECTIVE

This study aimed to evaluate the effect of maternal body mass index and lipid profile on first-trimester serum progesterone levels.

STUDY DESIGN

This was a prospective cohort study including 734 pregnant people. First-trimester maternal serum progesterone, cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides were measured between 9 and 11 weeks' gestation. Free β-hCG, PAPP-A, age, body mass index, smoking status, gestational age at delivery, fetal sex, and birthweight were also recorded. Pregnant people were classified according to their body mass index into underweight (n=21), normal weight (n=395), overweight (n=221), obesity class I (n=64), and obesity class II/III (n=33) groups.

RESULTS

Gestational age at sampling was 10.0 4±1.12 weeks. Serum progesterone levels decreased as maternal body mass index increased (35.84±12.00 ng/mL, 33.08±11.27 ng/mL, 28.04±8.91 ng/mL, 24.37±8.56 ng/mL, and 19.87±11.00 mL for underweight, normal weight, overweight, obesity class I, and obesity class II/III groups, respectively; P<.000001). There were statistically significant negative correlations between maternal progesterone and body mass index, triglycerides, and cholesterol/high-density lipoprotein cholesterol ratio, and positive correlations with gestational age at sampling, maternal age, cholesterol, high-density lipoprotein cholesterol, crown-rump length, free β-hCG, and PAPP-A. Linear regression showed that the only independent predictor variables for progesterone levels were body mass index (P<.0001), PAPP-A (P<.0001), high-density lipoprotein cholesterol (P<.0001), and free β-hCG (P<.0001) (R2=0.33; P<.0000001).

CONCLUSION

First-trimester serum progesterone levels were lower in overweight pregnant people and markedly decreased in those with obesity, especially obesity class II/III. Maternal high-density lipoprotein cholesterol was independently related to progesterone levels as a protective factor. Benefits of progesterone supplementation in pregnant people with obesity need further evaluation.

Fetal sex and the development of gestational diabetes mellitus in polycystic ovarian syndrome gravidae

BACKGROUND

Polycystic ovarian syndrome is characterized by elevated androgens and is a well-known risk factor for the occurrence of gestational diabetes mellitus. Androgens (particularly dehydroepiandrosterone-sulfate) are crucial for the development and characteristics of the male reproductive tract during fetal life, and fetal dehydroepiandrosterone-sulfate enters the placenta where it is metabolized and functions as an estrogen substrate. Given this unique sex-specific relationship with androgens and the association of serum dehydroepiandrosterone-sulfate concentration with insulin resistance, we hypothesized that metabolic comorbidities in pregnancy might differ by fetal sex in gravidae with polycystic ovarian syndrome, notably in those with infertility.

OBJECTIVE

This study aimed to evaluate the data in a large population-based database to explore if fetal sex was significantly associated with gestational diabetes mellitus in gravidae with infertility and polycystic ovarian syndrome after controlling for confounders.

STUDY DESIGN

This study was designed to evaluate the risk for the occurrence and rates of gestational diabetes mellitus among gravidae with infertility and a history of polycystic ovarian syndrome. We used a 2-hospital, single academic institution database comprising more than 30,000 subjects enrolled from September 2011 to June 2021 to identify all gravidae with diagnoses of infertility and polycystic ovarian syndrome at the time of delivery and to compare them with gravidae who lacked these comorbidities. Data on covariates, including but not limited to maternal age, body mass index, fetal sex, race, ethnicity, presence or absence of hypertensive disease, and presence or absence of gestational diabetes were identified. Unadjusted and adjusted odds rations were calculated.

RESULTS

We found a statistically significant association between fetal female sex and the development of gestational diabetes mellitus in gravidae with polycystic ovarian syndrome (odds ratio for female vs male, 2.13; 95% confidence interval, 1.06-4.32; P=.03). After adjusting for potential confounders identified in our univariate analyses, there continued to be a statistically significant association between female fetuses and the development of gestational diabetes mellitus (adjusted odds ratio for female vs male, 2.10; 95% confidence interval, 1.04-4.41; P=.04). In contrast, there was no significant association between fetal sex and the development of gestational diabetes mellitus in our similar analysis of gravidae without infertility and polycystic ovarian syndrome (P=.99).

CONCLUSION

Although the origin of gestational diabetes mellitus is multifactorial, we found that female fetal sex is associated with gestational diabetes mellitus in gravidae with infertility and polycystic ovarian syndrome but not in their comparative controls. Further research on the molecular mechanisms driving the association between female fetuses and the development of gestational diabetes mellitus in the context of maternal polycystic ovarian syndrome is warranted.

Placental transcriptomic signatures of spontaneous preterm birth

BACKGROUND

Spontaneous preterm birth accounts for most preterm births and leads to significant morbidity in the newborn and childhood period. This subtype of preterm birth represents an increasing proportion of all preterm births when compared with medically indicated preterm birth, yet it is understudied in omics analyses. The placenta is a key regulator of fetal and newborn health, and the placental transcriptome can provide insight into pathologic changes that lead to spontaneous preterm birth.

OBJECTIVE

This analysis aimed to identify genes for which placental expression was associated with spontaneous preterm birth (including early preterm and late preterm birth).

STUDY DESIGN

The ECHO PATHWAYS consortium extracted RNA from placental samples collected from the Conditions Affecting Neurocognitive Development and Learning in Early Childhood and the Global Alliance to Prevent Prematurity and Stillbirth studies. Placental transcriptomic data were obtained by RNA sequencing. Linear models were fit to estimate differences in placental gene expression between term birth and spontaneous preterm birth (including gestational age subgroups defined by the American College of Obstetricians and Gynecologists). Models were adjusted for numerous confounding variables, including labor status, cohort, and RNA sequencing batch. This analysis excluded patients with induced labor, chorioamnionitis, multifetal gestations, or medical indications for preterm birth. Our combined cohort contained gene expression data for 14,023 genes in 48 preterm and 540 term samples. Genes and pathways were considered statistically significantly different at false discovery rate-adjusted P value of <.05.

RESULTS

In total, we identified 1728 genes for which placental expression was associated with spontaneous preterm birth with more differences in expression in early preterm samples than late preterm samples when compared with full-term samples. Of those, 9 genes were significantly decreased in both early and late spontaneous preterm birth, and the strongest associations involved placental expression of IL1B, ALPL, and CRLF1. In early and late preterm samples, we observed decreased expression of genes involved in immune signaling, signal transduction, and endocrine function.

CONCLUSION

This study provides a comprehensive assessment of the differences in the placental transcriptome associated with spontaneous preterm birth with robust adjustment for confounding. Results of this study are in alignment with the known etiology of spontaneous preterm birth, because we identified multiple genes and pathways for which the placental and chorioamniotic membrane expression was previously associated with prematurity, including IL1B. We identified decreased expression in key signaling pathways that are essential for placental growth and function, which may be related to the etiology of spontaneous preterm birth. We identified increased expression of genes within metabolic pathways associated exclusively with early preterm birth. These signaling and metabolic pathways may provide clinically targetable pathways and biomarkers. The findings presented here can be used to understand underlying pathologic changes in premature placentas, which can inform and improve clinical obstetrics practice.

Serine Hydrolases in Lipid Homeostasis of the Placenta-Targets for Placental Function?

The metabolic state of pregnant women and their unborn children changes throughout pregnancy and adapts to the specific needs of each gestational week. These adaptions are accomplished by the actions of enzymes, which regulate the occurrence of their endogenous substrates and products in all three compartments: mother, placenta and the unborn. These enzymes determine bioactive lipid signaling, supply, and storage through the generation or degradation of lipids and fatty acids, respectively. This review focuses on the role of lipid-metabolizing serine hydrolases during normal pregnancy and in pregnancy-associated pathologies, such as preeclampsia, gestational diabetes mellitus, or preterm birth. The biochemical properties of each class of lipid hydrolases are presented, with special emphasis on their role in placental function or dysfunction. While, during a normal pregnancy, an appropriate tonus of bioactive lipids prevails, dysregulation and aberrant signaling occur in diseased states. A better understanding of the dynamics of serine hydrolases across gestation and their involvement in placental lipid homeostasis under physiological and pathophysiological conditions will help to identify new targets for placental function in the future.

Differences in Glycolysis and Mitochondrial Respiration between Cytotrophoblast and Syncytiotrophoblast In-Vitro: Evidence for Sexual Dimorphism

In the placenta the proliferative cytotrophoblast cells fuse into the terminally differentiated syncytiotrophoblast layer which undertakes several energy-intensive functions including nutrient uptake and transfer and hormone synthesis. We used Seahorse glycolytic and mitochondrial stress tests on trophoblast cells isolated at term from women of healthy weight to evaluate if cytotrophoblast (CT) and syncytiotrophoblast (ST) have different bioenergetic strategies, given their different functions. Whereas there are no differences in basal glycolysis, CT have significantly greater glycolytic capacity and reserve than ST. In contrast, ST have significantly higher basal, ATP-coupled and maximal mitochondrial respiration and spare capacity than CT. Consequently, under stress conditions CT can increase energy generation via its higher glycolytic capacity whereas ST can use its higher and more efficient mitochondrial respiration capacity. We have previously shown that with adverse in utero conditions of diabetes and obesity trophoblast respiration is sexually dimorphic. We found no differences in glycolytic parameters between sexes and no difference in mitochondrial respiration parameters other than increases seen upon syncytialization appear to be greater in females. There were differences in metabolic flexibility, i.e., the ability to use glucose, glutamine, or fatty acids, seen upon syncytialization between the sexes with increased flexibility in female trophoblast suggesting a better ability to adapt to changes in nutrient supply.

The role of xenobiotic-metabolizing enzymes in the placenta: a growing research field

Introduction: The placenta is a temporary and unique organ that allows for the physical connection between a mother and fetus; this organ regulates the transport of gases and nutrients mediating the elimination of waste products contained in the fetal circulation. The placenta performs metabolic and excretion functions, on the basis of multiple enzymatic systems responsible for the oxidation, reduction, hydrolysis, and conjugation of xenobiotics. These mechanisms give the placenta a protective role that limits the fetal exposure to harmful compounds. During pregnancy, some diseases require uninterrupted treatment even if it is detrimental to the fetus. Drugs and other xenobiotics alter gene expression in the placenta with repercussions for the fetus and mother's well-being.Areas covered: This review provides a brief description of the human placental structure and function, the main drug and xenobiotic transporters and metabolizing enzymes, placenta-metabolized substrates, and alterations in gene expression that the exposure to xenobiotics may cause.Expert opinion: Research should be focused on the identification and validation of biological markers for the assessment of the harmful effects of some drugs in pregnancy, including the evaluation of polymorphisms and methylation patterns in chorionic villous samples and/or amniotic fluid.