Placental lipid droplet composition: Effect of a lifestyle intervention (UPBEAT) in obese pregnant women

Human placental lipid content and lipid metabolic enzyme abundance in obesity and across gestation

Changes in placental lipid metabolism influence the delivery of lipids critical for fetal development and fetal requirements for lipids change across gestation. We hypothesized that placental lipid content and metabolic enzyme protein levels increase across gestation and are elevated in obesity. Placentas (4-40 weeks' gestation) were collected from control (body mass index, BMI = 18.5-24.9, n=37) and obese (BMI > 30, n=19) pregnant women. Trophoblast villous tissue was homogenized and subjected to liquid chromatography tandem mass spectrometry (LC-MS/MS) for phospholipid and triacylglycerol (TAG) analysis and western blot for protein quantification. The placental content of TAG species and nine of 35 identified phosphatidylcholines (PC) were significantly higher (P<0.05) in first trimester (28-79%, 10-47%, respectively). Furthermore, two TAG and three PC differed by maternal BMI and were significantly increased (P<0.05) in the obese group in first trimester (72-87%, 88-119%, respectively). Placental protein abundance of glycerol-2-phosphate (GPAT3) and 1-acyl-sn-glycerol-3-phosphate acyltransferase 2 (AGPAT2), involved in de novo synthesis of PC and TAG, were higher (P<0.05) in the first trimester (66 and 74%, respectively). The protein abundance of the PC-remodeling enzyme PLA2G4c was also higher (63%) in first trimester (P<0.05). In conclusion, the placental content of many phospholipid and TAG species and the protein level of associated synthesis enzymes are higher in first-trimester human placenta. The high PC content may be related to the rapid membrane expansion in early pregnancy and the low placental oxygen tension may promote the accumulation of tissue TAGs in first trimester. Maternal obesity had only limited impact on placental lipid content and metabolic enzyme protein abundance.

Placental 13C-DHA metabolism and relationship with maternal BMI, glycemia and birthweight

BACKGROUND

Fetal docosahexaenoic acid (DHA) supply relies on preferential transplacental transfer, which is regulated by placental DHA lipid metabolism. Maternal hyperglycemia and obesity associate with higher birthweight and fetal DHA insufficiency but the role of placental DHA metabolism is unclear.

METHODS

Explants from 17 term placenta were incubated with 13C-labeled DHA for 48 h, at 5 or 10 mmol/L glucose treatment, and the production of 17 individual newly synthesized 13C-DHA labeled lipids quantified by liquid chromatography mass spectrometry.

RESULTS

Maternal BMI positively associated with 13C-DHA-labeled diacylglycerols, triacylglycerols, lysophospholipids, phosphatidylcholine and phosphatidylethanolamine plasmalogens, while maternal fasting glycemia positively associated with five 13C-DHA triacylglycerols. In turn, 13C-DHA-labeled phospholipids and triacylglycerols positively associated with birthweight centile. In-vitro glucose treatment increased most 13C-DHA-lipids, but decreased 13C-DHA phosphatidylethanolamine plasmalogens. However, with increasing maternal BMI, the magnitude of the glucose treatment induced increase in 13C-DHA phosphatidylcholine and 13C-DHA lysophospholipids was curtailed, with further decline in 13C-DHA phosphatidylethanolamine plasmalogens. Conversely, with increasing birthweight centile glucose treatment induced increases in 13C-DHA triacylglycerols were exaggerated, while glucose treatment induced decreases in 13C-DHA phosphatidylethanolamine plasmalogens were diminished.

CONCLUSIONS

Maternal BMI and glycemia increased the production of different placental DHA lipids implying impact on different metabolic pathways. Glucose-induced elevation in placental DHA metabolism is moderated with higher maternal BMI. In turn, findings of associations between many DHA lipids with birthweight suggest that BMI and glycemia promote fetal growth partly through changes in placental DHA metabolism.

Effects of Maternal Obesity On Placental Phenotype

The incidence of obesity is rising rapidly worldwide with the consequence that more women are entering pregnancy overweight or obese. This leads to an increased incidence of clinical complications during pregnancy and of poor obstetric outcomes. The offspring of obese pregnancies are often macrosomic at birth although there is also a subset of the progeny that are growth-restricted at term. Maternal obesity during pregnancy is also associated with cardiovascular, metabolic and endocrine dysfunction in the offspring later in life. As the interface between the mother and fetus, the placenta has a central role in programming intrauterine development and is known to adapt its phenotype in response to environmental conditions such as maternal undernutrition and hypoxia. However, less is known about placental function in the abnormal metabolic and endocrine environment associated with maternal obesity during pregnancy. This review discusses the placental consequences of maternal obesity induced either naturally or experimentally by increasing maternal nutritional intake and/or changing the dietary composition. It takes a comparative, multi-species approach and focusses on placental size, morphology, nutrient transport, metabolism and endocrine function during the later stages of obese pregnancy. It also examines the interventions that have been made during pregnancy in an attempt to alleviate the more adverse impacts of maternal obesity on placental phenotype. The review highlights the potential role of adaptations in placental phenotype as a contributory factor to the pregnancy complications and changes in fetal growth and development that are associated with maternal obesity.

Personalized Nutrition Approach in Pregnancy and Early Life to Tackle Childhood and Adult Non-Communicable Diseases

The development of childhood and adult non-communicable diseases (NCD) is associated with environmental factors, starting from intrauterine life. A new theory finds the roots of epigenetic programming in parental gametogenesis, continuing during embryo development, fetal life, and finally in post-natal life. Maternal health status and poor nutrition are widely recognized as implications in the onset of childhood and adult diseases. Early nutrition, particularly breastfeeding, also plays a primary role in affecting the health status of an individual later in life. A poor maternal diet during pregnancy and lack of breastfeeding can cause a nutrient deficiency that affects the gut microbiota, and acts as a cofactor for many pathways, impacting the epigenetic controls and transcription of genes involved in the metabolism, angiogenesis, and other pathways, leading to NCDs in adult life. Both maternal and fetal genetic backgrounds also affect nutrient adsorption and functioning at the cellular level. This review discusses the most recent evidence on maternal nutrition and breastfeeding in the development of NCD, the potentiality of the omics technologies in uncovering the molecular mechanisms underlying it, with the future prospective of applying a personalized nutrition approach to prevent and treat NCD from the beginning of fetal life.

Towards an Optimized Fetal DHA Accretion: Differences on Maternal DHA Supplementation Using Phospholipids vs. Triglycerides during Pregnancy in Different Models

Docosahexaenoic acid (DHA) supplementation during pregnancy has been recommended by several health organizations due to its role in neural, visual, and cognitive development. There are several fat sources available on the market for the manufacture of these dietary supplements with DHA. These fat sources differ in the lipid structure in which DHA is esterified, mainly phospholipids (PL) and triglycerides (TG) molecules. The supplementation of DHA in the form of PL or TG during pregnancy can lead to controversial results depending on the animal model, physiological status and the fat sources utilized. The intestinal digestion, placental uptake, and fetal accretion of DHA may vary depending on the lipid source of DHA ingested by the mother. The form of DHA used in maternal supplementation that would provide an optimal DHA accretion for fetal brain development, based on the available data obtained most of them from different animal models, indicates no consistent differences in fetal accretion when DHA is provided as TG or PL. Other related lipid species are under evaluation, e.g., lyso-phospholipids, with promising results to improve DHA bioavailability although more studies are needed. In this review, the evidence on DHA bioavailability and accumulation in both maternal and fetal tissues after the administration of DHA supplementation during pregnancy in the form of PL or TG in different models is summarized.

Serum Metabolic Profiles of Chinese Women With Perimenopausal Obesity Explored by the Untargeted Metabolomics Approach

By far, no study has focused on observing the metabolomic profiles in perimenopause-related obesity. This study attempted to identify the metabolic characteristics of subjects with perimenopause obesity (PO). Thirty-nine perimenopausal Chinese women, 21 with PO and 18 without obesity (PN), were recruited in this study. A conventional ultra-high-performance liquid chromatography-quadrupole time-of-flight/mass spectrometry (UHPLC-QTOF/MS) followed by principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLS-DA) were used as untargeted metabolomics approaches to explore the serum metabolic profiles. Kyoto Encyclopedia of Genes and Genomes (KEGG) and MetaboAnalyst were used to identify the related metabolic pathways. A total of 46 differential metabolites, along with seven metabolic pathways relevant to PO were identified, which belonged to lipid, amino acids, carbohydrates, and organic acids. As for amino acids, we found a significant increase in l-arginine and d-ornithine in the positive ion (POS) mode and l-leucine, l-valine, l-tyrosine, and N-acetyl-l-tyrosine in the negative ion (NEG) mode and a significant decrease in l-proline in the POS mode of the PO group. We also found phosphatidylcholine (PC) (16:0/16:0), palmitic acid, and myristic acid, which are associated with the significant upregulation of lipid metabolism. Moreover, the serum indole lactic acid and indoleacetic acid were upregulated in the NEG mode. With respect to the metabolic pathways, the d-arginine and d-ornithine metabolisms and the arginine and proline metabolism pathways in POS mode were the most dominant PO-related pathways. The changes of metabolisms of lipid, amino acids, and indoleacetic acid provided a pathophysiological scenario for Chinese women with PO. We believe that the findings of this study are helpful for clinicians to take measures to prevent the women with PO from developing severe incurable obesity-related complications, such as cardiovascular disease and stroke.

Maternal obesity alters placental lysophosphatidylcholines, lipid storage, and the expression of genes associated with lipid metabolism‡

Dyslipidemia is a characteristic of maternal obesity and previous studies have demonstrated abnormalities in fatty acid oxidation and storage in term placentas. However, there is little information about the effect of pre-pregnancy obesity on placental lipid metabolism during early pregnancy. The objective of this study was to determine the relationship between lipid profiles and markers of metabolism in placentas from obese and lean dams at midgestation. Mice were fed a western diet (WD) or normal diet (ND) and lysophosphatidylcholines (LPCs) and/or phosphatidylcholines (PCs) were measured in dam circulation and placenta sections using liquid chromatography-tandem mass spectrometry and mass spectrometry imaging, respectively. In WD dam, circulating LPCs containing 16:1, 18:1, 20:0, and 20:3 fatty acids were increased and 18:2 and 20:4 were decreased. In WD placenta from both sexes, LPC 18:1 and PC 36:1 and 38:3 were increased. Furthermore, there were moderate to strong correlations between LPC 18:1, PC 36:1, and PC 38:3. Treatment-, spatial-, and sex-dependent differences in LPC 20:1 and 20:3 were also detected. To identify genes that may regulate diet-dependent differences in placenta lipid profiles, the expression of genes associated with lipid metabolism and nutrient transport was measured in whole placenta and isolated labyrinth using droplet digital PCR and Nanostring nCounter assays. Several apolipoproteins were increased in WD placentas. However, no differences in nutrient transport or fatty acid metabolism were detected. Together, these data indicate that lipid storage is increased in midgestation WD placentas, which may lead to lipotoxicity, altered lipid metabolism and transport to the fetus later in gestation.

The Impact of Maternal Body Composition and Dietary Fat Consumption upon Placental Lipid Processing and Offspring Metabolic Health

The proportion of women of reproductive age who are overweight or obese is increasing globally. Gestational obesity is strongly associated in both human studies and animal models with early-onset development of adult-associated metabolic diseases including metabolic syndrome in the exposed offspring. However, animal model studies have suggested that gestational diet in obese pregnancies is an independent but underappreciated mediator of offspring risk for later life metabolic disease, and human diet consumption data have highlighted that many women do not follow nutritional guidelines prior to and during pregnancy. Thus, this review will highlight how maternal diet independent from maternal body composition impacts the risk for later-life metabolic disease in obesity-exposed offspring. A poor maternal diet, in combination with the obese metabolic state, are understood to facilitate pathological in utero programming, specifically through changes in lipid handling processes in the villous trophoblast layer of the placenta that promote an environment associated with the development of metabolic disease in the offspring. This review will additionally highlight how maternal obesity modulates villous trophoblast lipid processing functions including fatty acid transport, esterification and beta-oxidation. Further, this review will discuss how altering maternal gestational diet may ameliorate these functional changes in lipid metabolic processes in the obese placenta.

Maternal lipid levels across pregnancy impact the umbilical cord blood lipidome and infant birth weight

Major alterations in metabolism occur during pregnancy enabling the mother to provide adequate nutrients to support infant development, affecting birth weight (BW) and potentially long-term risk of obesity and cardiometabolic disease. We classified dynamic changes in the maternal lipidome during pregnancy and identified lipids associated with Fenton BW z-score and the umbilical cord blood (CB) lipidome. Lipidomics was performed on first trimester maternal plasma (M1), delivery maternal plasma (M3), and CB plasma in 106 mother-infant dyads. Shifts in the maternal and CB lipidome were consistent with the selective transport of long-chain polyunsaturated fatty acids (PUFA) as well as lysophosphatidylcholine (LysoPC) and lysophosphatidylethanolamine (LysoPE) species into CB. Partial correlation networks demonstrated fluctuations in correlations between lipid groups at M1, M3, and CB, signifying differences in lipid metabolism. Using linear models, LysoPC and LysoPE groups in CB were positively associated with BW. M1 PUFA containing triglycerides (TG) and phospholipids were correlated with CB LysoPC and LysoPE species and total CB polyunsaturated TGs. These results indicate that early gestational maternal lipid levels influence the CB lipidome and its relationship with BW, suggesting an opportunity to modulate maternal diet and improve long-term offspring cardiometabolic health.

Nutritional Lifestyle Intervention in Obese Pregnant Women, Including Lower Carbohydrate Intake, Is Associated With Increased Maternal Free Fatty Acids, 3-β-Hydroxybutyrate, and Fasting Glucose Concentrations: A Secondary Factorial Analysis of the European Multicenter, Randomized Controlled DALI Lifestyle Intervention Trial

OBJECTIVE

In our randomized controlled trial, we investigated the impact of healthy eating (HE) aiming for restricted gestational weight gain (GWG) and physical activity (PA) interventions on maternal and neonatal lipid metabolism.

RESEARCH DESIGN AND METHODS

Obese pregnant women (n = 436) were included before 20 weeks' gestation and underwent glucose testing (oral glucose tolerance test) and lipid profiling at baseline and 24-28 and 35-37 gestational weeks after an at least 10-h overnight fast. This secondary analysis had a factorial design with comparison of HE (n = 221) versus no HE (n = 215) and PA (n = 218) versus no PA (n = 218). Maternal changes in triglycerides (TG), LDL cholesterol, HDL cholesterol, free fatty acids (FFAs), and leptin from baseline to end of pregnancy and neonatal outcomes were analyzed using general linear models with adjustment for relevant parameters.

RESULTS

At 24-28 weeks' gestation, FFAs (mean ± SD, 0.60 ± 0.19 vs. 0.55 ± 0.17 mmol/L, P < 0.01) were increased after adjustment for FFA at baseline, maternal age, BMI at time of examination, gestational week, insulin resistance, self-reported food intake, self-reported physical activity, and maternal smoking, and GWG was lower (3.3 ± 2.6 vs. 4.3 ± 2.8 kg, P < 0.001, adjusted mean differences -1.0 [95% CI -1.5; -0.5]) in HE versus no HE. Fasting glucose levels (4.7 ± 0.4 vs. 4.6 ± 0.4 mmol/L, P < 0.05) and 3-β-hydroxybutyrate (3BHB) (0.082 ± 0.065 vs. 0.068 ± 0.067 mmol/L, P < 0.05) were higher in HE. Significant negative associations between carbohydrate intake and FFA, 3BHB, and fasting glucose at 24-28 weeks' gestation were observed. No differences between groups were found in oral glucose tolerance test or leptin or TG levels at any time. Furthermore, in PA versus no PA, no similar changes were found. In cord blood, elevated FFA levels were found in HE after full adjustment (0.34 ± 0.22 vs. 0.29 ± 0.16 mmol/L, P = 0.01).

CONCLUSIONS

HE intervention was associated with reduced GWG, higher FFAs, higher 3BHB, and higher fasting glucose at 24-28 weeks of gestation, suggesting induction of lipolysis. Increased FFA was negatively associated with carbohydrate intake and was also observed in cord blood. These findings support the hypothesis that maternal antenatal dietary restriction including carbohydrates is associated with increased FFA mobilization.