Differential placental ceramide levels during gestational diabetes mellitus (GDM)

Next Generation, Modifiable Cardiometabolic Biomarkers: Mitochondrial Adaptation and Metabolic Resilience: A Scientific Statement From the American Heart Association

Cardiometabolic risk is increasing in prevalence across the life span with disproportionate ramifications for youth at socioeconomic disadvantage. Established risk factors and associated disease progression are harder to reverse as they become entrenched over time; if current trends are unchecked, the consequences for individual and societal wellness will become untenable. Interrelated root causes of ectopic adiposity and insulin resistance are understood but identified late in the trajectory of systemic metabolic dysregulation when traditional cardiometabolic risk factors cross current diagnostic thresholds of disease. Thus, children at cardiometabolic risk are often exposed to suboptimal metabolism over years before they present with clinical symptoms, at which point life-long reliance on pharmacotherapy may only mitigate but not reverse the risk. Leading-edge indicators are needed to detect the earliest departure from healthy metabolism, so that targeted, primordial, and primary prevention of cardiometabolic risk is possible. Better understanding of biomarkers that reflect the earliest transitions to dysmetabolism, beginning in utero, ideally biomarkers that are also mechanistic/causal and modifiable, is critically needed. This scientific statement explores emerging biomarkers of cardiometabolic risk across rapidly evolving and interrelated "omic" fields of research (the epigenome, microbiome, metabolome, lipidome, and inflammasome). Connections in each domain to mitochondrial function are identified that may mediate the favorable responses of each of the omic biomarkers featured to a heart-healthy lifestyle, notably to nutritional interventions. Fuller implementation of evidence-based nutrition must address environmental and socioeconomic disparities that can either facilitate or impede response to therapy.

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.

Sphingolipids and acylcarnitines are altered in placentas from women with gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is the most common medical complication of pregnancy and a severe threat to pregnant people and offspring health. The molecular origins of GDM, and in particular the placental responses, are not fully known. The present study aimed to perform a comprehensive characterisation of the lipid species in placentas from pregnancies complicated with GDM using high-resolution MS lipidomics, with a particular focus on sphingolipids and acylcarnitines in a semi-targeted approach. The results indicated that despite no major disruption in lipid metabolism, placentas from GDM pregnancies showed significant alterations in sphingolipids, mostly lower abundance of total ceramides. Additionally, very long-chain ceramides and sphingomyelins with twenty-four carbons were lower, and glucosylceramides with sixteen carbons were higher in placentas from GDM pregnancies. Semi-targeted lipidomics revealed the strong impact of GDM on the placental acylcarnitine profile, particularly lower contents of medium and long-chain fatty-acyl carnitine species. The lower contents of sphingolipids may affect the secretory function of the placenta, and lower contents of long-chain fatty acylcarnitines is suggestive of mitochondrial dysfunction. These alterations in placental lipid metabolism may have consequences for fetal growth and development.

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.

Distinct Changes in Placental Ceramide Metabolism Characterize Type 1 and 2 Diabetic Pregnancies with Fetal Macrosomia or Preeclampsia

Disturbances of lipid metabolism are typical in diabetes. Our objective was to characterize and compare placental sphingolipid metabolism in type 1 (T1D) and 2 (T2D) diabetic pregnancies and in non-diabetic controls. Placental samples from T1D, T2D, and control pregnancies were processed for sphingolipid analysis using tandem mass spectrometry. Western blotting, enzyme activity, and immunofluorescence analyses were used to study sphingolipid regulatory enzymes. Placental ceramide levels were lower in T1D and T2D compared to controls, which was associated with an upregulation of the ceramide degrading enzyme acid ceramidase (ASAH1). Increased placental ceramide content was found in T1D complicated by preeclampsia. Similarly, elevated ceramides were observed in T1D and T2D pregnancies with poor glycemic control. The protein levels and activity of sphingosine kinases (SPHK) that produce sphingoid-1-phosphates (S1P) were highest in T2D. Furthermore, SPHK levels were upregulated in T1D and T2D pregnancies with fetal macrosomia. In vitro experiments using trophoblastic JEG3 cells demonstrated increased SPHK expression and activity following glucose and insulin treatments. Specific changes in the placental sphingolipidome characterize T1D and T2D placentae depending on the type of diabetes and feto-maternal complications. Increased exposure to insulin and glucose is a plausible contributor to the upregulation of the SPHK-S1P-axis in diabetic placentae.

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.

Molecular Mechanism of miR-29b on Gestational Diabetes and Its Influence on Trophoblast Cell Function

To explore the mechanism of miR-29b in gestational diabetes mellitus (GDM) and its effect on the function of trophoblast cell (TBC), the placenta tissues of 55 normal term pregnancies and 55 GDM patients were selected and rolled into control group and observation group. In the early stage, microRNA (miRNA) chips were utilized to screen the differentially expressed miRNAs in the placenta of observation group and control group. According to the microarray results of miRNAs, three differentially expressed miRNAs, namely let-7b, miR-1202, and miR-29b were selected. Then, the differences in the miR-29b level in the four groups were analyzed, namely the microRNA-29b (miR-29b minic), mini-control (minic control), microRNA-29b inhibitor (miR-29b inhibitor), and inhibitor control (inhibitor control). The results showed that miR-29b level in the placenta of observation group was substantially inferior to that of controls, with remarkable differences (P < 0.05). miR-29b level in miR-29b minic and minic control had significant changes (P < 0.01). The TBC activity of minic control was greatly superior to that of minic control, and there was considerable difference between the two (P < 0.05). The difference between miR-29b inhibitor and inhibitor control in TBC was not obvious, without considerable differences (P > 0.05). The invasion ability of miR-29b inhibitor TBC was notably superior to inhibitor control, and there were substantial differences (P < 0.05). To sum up, miR-29b had a significant inhibitory effect on the proliferation and cell activity of TBC, and can promote the apoptosis and death of TBC. Moreover, its inhibitory effect on cell migration and invasion was also suggested.

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.

Placental structural abnormalities in gestational diabetes and when they develop: A scoping review

Gestational diabetes mellitus (GDM) is defined as diabetes with onset or first recognition during gestation. It is a common complication of pregnancy that has become more prevalent over the past few decades. Abnormalities in fetal growth, including increased incidence of both large and small for gestational age babies, suggest placental dysfunction. The major goal of this scoping review is to determine what is known about abnormalities in placentas delivered from GDM pregnancies, and how early in gestation these abnormalities arise. A secondary goal is to review to what extent other selected factors, in particular obesity, have been found to influence or modify the reported effects of GDM on placental development, and whether these are considered in the study of GDM placentas. PubMed and Scopus databases were searched using the key terms: "gestational diabetes AND (woman OR human) AND placenta AND (ultrasound OR ultrastructure OR imaging OR histology OR pathology). Studies of gross morphology and histoarchitecture in placentas delivered from GDM pregnancies consistently report increased placental size, villous immaturity and a range of vascular lesions when compared to uncomplicated pregnancies. In contrast, a small number of ultrasound studies have examined placental development in GDM pregnancies in the second, and especially, the first trimester. Relatively few studies have analyzed interactions with maternal BMI, but these do suggest that it may play a role in placental abnormalities. Further examination of placental development early in pregnancy is needed to understand when it becomes disrupted in GDM, as a first step to identifying the underlying causes.

Neutral Ceramidase Is Required for the Reproduction of Brown Planthopper, Nilaparvata lugens (Stål)

Ceramides are bioactive sphingolipids that have been implicated in insect development; however, their role in insect reproduction remains poorly understood. Here, we report the pivotal role of neutral ceramidase (NCER) in the female reproduction of the brown planthopper (BPH), Nilaparvata lugens (Stål), a significant pest in rice cultivation in Asia. LC-MS/MS demonstrated that, among different developmental stages of BPH, the levels of ceramides were highest in 1st instar nymphs and lowest in adults. The transcription of NCER was negatively correlated with the levels of ceramides at different developmental stages of BPH, in that the transcript levels of NCER were the highest, whereas ceramides levels were the lowest in BPH adults. Knocking down NCER through RNA interference (RNAi) increased the levels of ceramides in BPH females and ovaries, which resulted in a delay in oocyte maturation, a reduction in oviposition and egg hatching rate, as well as the production of vulnerable offspring. Transmission electron microscopy (TEM) analysis and TdT-mediated dUTP Nick-End Labeling (TUNEL) assays showed mitochondrial deficiency and apoptosis in NCER-deficient oocytes. Taken together, these results suggest that NCER plays a crucial role in female reproduction in BPH, likely by regulating the levels of ceramides.

Placental Inositol Reduced in Gestational Diabetes as Glucose Alters Inositol Transporters and IMPA1 Enzyme Expression

CONTEXT

Perturbed inositol physiology in insulin-resistant conditions has led to proposals of inositol supplementation for gestational diabetes (GDM) prevention, but placental inositol biology is poorly understood.

OBJECTIVE

Investigate associations of maternal glycemia with placental inositol content, determine glucose effects on placental expression of inositol enzymes and transporters, and examine relations with birthweight.

DESIGN AND PARTICIPANTS

Case-control study of placentae from term singleton pregnancies (GDM n = 24, non-GDM n = 26), and culture of another 9 placentae in different concentrations of glucose and myo-inositol for 48 hours.

MAIN OUTCOME MEASURES

Placental inositol was quantified by the Megazyme assay. Relative expression of enzymes involved in myo-inositol metabolism and plasma membrane inositol transport was determined by quantitative RT-PCR and immunoblotting. Linear regression analyses were adjusted for maternal age, body mass index, ethnicity, gestational age, and sex.

RESULTS

Placental inositol content was 17% lower in GDM compared with non-GDM. Higher maternal mid-gestation glycemia were associated with lower placental inositol. Increasing fasting glycemia was associated with lower protein levels of the myo-inositol synthesis enzyme, IMPA1, and the inositol transporters, SLC5A11 and SLC2A13, the expression of which also correlated with placental inositol content. In vitro, higher glucose concentrations reduced IMPA1 and SLC5A11 mRNA expression. Increasing fasting glycemia positively associated with customized birthweight percentile as expected in cases with low placental inositol, but this association was attenuated with high placental inositol.

CONCLUSION

Glycemia-induced dysregulation of placental inositol synthesis and transport may be implicated in reduced placental inositol content in GDM, and this may in turn be permissive to accelerated fetal growth.

The role of Smad4 in the regulation of insulin resistance, inflammation and cell proliferation in HTR8-Svneo cells

Gestational diabetes mellitus (GDM) is a metabolic disorder whose major pathophysiological basis is demonstrated as placental insulin resistance (IR), while Smad4 always functions in the signal transduction of transforming growth factor beta (TGF-β) pathway. Our study aims to figure out the role of Smad4 in an insulin resistance (IR) cellular model using placental trophoblast cell line. Importantly, HTR8-Svneo cells, in the status of IR, indicated a significant increase in the expression of Smad4. Subsequently, the HTR8-Svneo cell line with up-regulated or depleted Smad4 was respectively achieved by the effective over-expressed plasmid or siRNA of Smad4. We found out that the deficiency of Smad4 could promote the insulin sensitivity and restrict the inflammatory response in IR group of cells with significant augment in glucose uptake, up-regulation of insulin signalling-related molecules and attenuation in inflammatory biomarker expressions. On the contrary, the over-expression of Smad4 showed a reversal effect on these alterations in IR group of cells. Besides, the positive effect of Smad4 on cell viability was also observed in our study. SIGNIFICANCE OF THE STUDY: Gestational diabetes mellitus (GDM) is a metabolic disorder whose major pathophysiological basis is demonstrated as insulin resistance (IR). Importantly, our findings indicate that the deficiency of Smad4 significantly improves the insulin sensitivity and relieves the inflammation in the cellular model of IR. Besides, the positive effect of Smad4 on cell viability was also observed in our study. Our present findings provide novel insights for the investigation on molecular details about the GDM pathogenesis.

Mitochondrial dysfunction in the fetoplacental unit in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease of pregnancy that is associated with d-glucose intolerance and foeto-placental vascular dysfunction. GMD causes mitochondrial dysfunction in the placental endothelium and trophoblast. Additionally, GDM is associated with reduced placental oxidative phosphorylation due to diminished activity of the mitochondrial F₀F₁-ATP synthase (complex V). This phenomenon may result from a higher generation of reactive superoxide anion and nitric oxide. Placental mitochondrial biogenesis and mitophagy work in concert to maintain cell homeostasis and are vital mechanisms securing the efficient generation of ATP, whose demand is higher in pregnancy, ensuring foetal growth and development. Additional factors disturbing placental ATP synthase activity in GDM include pre-gestational maternal obesity or overweight, intracellular pH, miRNAs, fatty acid oxidation, and foetal (and 'placental') sex. GDM is also associated with maternal and foetal hyperinsulinaemia, altered circulating levels of adiponectin and leptin, and the accumulation of extracellular adenosine. Here, we reviewed the potential interplay between these molecules or metabolic conditions on the mechanisms of mitochondrial dysfunction in the foeto-placental unit in GDM pregnancies.

The Role of Prenatal Melatonin in the Regulation of Childhood Obesity

There is a growing awareness that pregnancy can set the foundations for an array of diverse medical conditions in the offspring, including obesity. A wide assortment of factors, including genetic, epigenetic, lifestyle, and diet can influence foetal outcomes. This article reviews the role of melatonin in the prenatal modulation of offspring obesity. A growing number of studies show that many prenatal risk factors for poor foetal metabolic outcomes, including gestational diabetes and night-shift work, are associated with a decrease in pineal gland-derived melatonin and associated alterations in the circadian rhythm. An important aspect of circadian melatonin’s effects is mediated via the circadian gene, BMAL1, including in the regulation of mitochondrial metabolism and the mitochondrial melatoninergic pathway. Alterations in the regulation of mitochondrial metabolic shifts between glycolysis and oxidative phosphorylation in immune and glia cells seem crucial to a host of human medical conditions, including in the development of obesity and the association of obesity with the risk of other medical conditions. The gut microbiome is another important hub in the pathoetiology and pathophysiology of many medical conditions, with negative consequences mediated by a decrease in the short-chain fatty acid, butyrate. The effects of butyrate are partly mediated via an increase in the melatoninergic pathway, indicating interactions of the gut microbiome with melatonin. Some of the effects of melatonin seem mediated via the alpha 7 nicotinic receptor, whilst both melatonin and butyrate may regulate obesity through the opioidergic system. Oxytocin, a recently recognized inhibitor of obesity, may also be acting via the opioidergic system. The early developmental regulation of these processes and factors by melatonin are crucial to the development of obesity and many diverse comorbidities.