Placental lipase expression in pregnancies complicated by preeclampsia: a case-control study

Single-Cell RNA Sequencing and Microarray Analysis Reveal the Role of Lipid-Metabolism-Related Genes and Cellular Immune Infiltration in Pre-Eclampsia and Identify Novel Biomarkers for Pre-Eclampsia

Pre-eclampsia (PE) is a gestational hypertensive disorder that is characterized by hypertension and proteinuria, typically occurring after 20 weeks of gestation. Despite its global impact on pregnant women, the precise pathogenic mechanisms of PE remain unclear. Dysregulated lipid metabolism and immune cell infiltration contribute to PE development. Our study aimed to identify lipid-metabolism-related genes (LMRG-PEs) and investigate their association with immune infiltration. We utilized the "Seurat" R package for data quality control, cell clustering, and marker gene identification. The "SingleR" package enabled the matching of marker genes to specific cell types. Pseudotemporal ordering analysis was conducted using the "Monocle" package. Weighted correlation network analysis (WGCNA), gene set variation analysis (GSVA), and gene set enrichment analysis (GSEA) approaches were employed to explore lipid-metabolism-related genes, while potential targeted drugs were predicted using the drug-gene interaction database (DGIdb). Hub gene expression was validated through RT-qPCR. By analyzing single-cell RNA sequencing data, we identified and classified 20 cell clusters into 5 distinct types. Differential gene expression analysis revealed 186 DEGs. WGCNA identified 9 critical modules and 265 genes significantly associated with PE diagnosis, emphasizing the importance of the core genes PLA2G7 and PTGS2. RT-qPCR confirmed the significantly decreased expression of PLA2G7 and PTGS2 in PE patient tissues. These findings offer valuable insights into the molecular mechanisms of PE, particularly those involving lipid metabolism and immune infiltration. The identified hub genes have potential as therapeutic targets and biomarkers for future research and clinical applications.

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.

The Relationship between Angiogenic Factors and Energy Metabolism in Preeclampsia

Antiangiogenic factors are currently used for the prediction of preeclampsia. The present study aimed to evaluate the relationship between antiangiogenic factors and lipid and carbohydrate metabolism in maternal plasma and placenta. We analyzed 56 pregnant women, 30 healthy and 26 with preeclampsia (including early and late onset). We compared antiangiogenic factors soluble Fms-like Tyrosine Kinase-1 (sfLt-1), placental growth factor (PlGF), and soluble endoglin (sEng)), lipid and carbohydrate metabolism in maternal plasma, and lipid metabolism in the placenta from assays of fatty acid oxidation, fatty acid esterification, and triglyceride levels in all groups. Antiangiogenic factors sFlt-1, sFlt-1/PlGF ratio, and sEng showed a positive correlation with triglyceride, free fatty acid, and C-peptide maternal serum levels. However, there was no relationship between angiogenic factors and placental lipid metabolism parameters. Free fatty acids were predictive of elevated sFlt-1 and sEng, while C-peptide was predictive of an elevated sFlt1/PlGF ratio. The findings in this study generate a model to predict elevated antiangiogenic factor values and the relationship between them with different products of lipid and carbohydrate metabolism in maternal serum and placenta in preeclampsia.

G protein-coupled estrogen receptor stimulates human trophoblast cell invasion via YAP-mediated ANGPTL4 expression

Insufficient invasion of trophoblast cells into the uterine decidua is associated with preeclampsia (PE). G protein-coupled estrogen receptor (GPER) is a membrane estrogen receptor involved in non-genomic estrogen signaling. GPER is expressed in human trophoblast cells and downregulated GPER levels are noted in PE. However, to date, the role of GPER in trophoblast cells remains largely unknown. Here, we applied RNA sequencing (RNA-seq) to HTR-8/SVneo human trophoblast cells in response to G1, an agonist of GPER, and identified angiopoietin-like 4 (ANGPTL4) as a target gene of GPER. Treatment of trophoblast cells with G1 or 17β-estradiol (E2) activated Yes-associated protein (YAP), the major downstream effector of the Hippo pathway, via GPER but in a mammalian STE20-like protein kinase 1 (MST1)-independent manner. Using pharmacological inhibitors as well as loss- and gain-of-function approaches, our results revealed that YAP activation was required for GPER-stimulated ANGPTL4 expression. Transwell invasion assays demonstrated that activation of GPER-induced ANGPTL4 promoted cell invasion. In addition, the expression levels of GPER, YAP, and ANGPTL4 were downregulated in the placenta of patients with PE. Our findings reveal a mechanism by which GPER exerts its stimulatory effect on human trophoblast cell invasion by upregulating YAP-mediated ANGPTL4 expression.

Cheng, Fan, Li et al. identified ANGPTL4 as a G1-induced target gene of GPER/YAP in HRT8 cells using RNA-seq and highlighted its importance in regulating trophoblast cell invasion. The authors also reported GPER downregulation in the placenta and lower estradiol levels in patients who developed preeclampsia.

Short-Chain Fatty Acids, Maternal Microbiota and Metabolism in Pregnancy

Short-chain fatty acids (SCFAs), as products of intestinal bacterial metabolism, are particularly relevant in the diagnosis of intestinal dysbiosis. The most common studies of microbiome metabolites include butyric acid, propionic acid and acetic acid, which occur in varying proportions depending on diet, age, coexisting disease and other factors. During pregnancy, metabolic changes related to the protection of energy homeostasis are of fundamental importance for the developing fetus, its future metabolic fate and the mother’s health. SCFAs act as signaling molecules that regulate the body’s energy balance through G-protein receptors. GPR41 receptors affect metabolism through the microflora, while GPR43 receptors are recognized as a molecular link between diet, microflora, gastrointestinal tract, immunity and the inflammatory response. The possible mechanism by which the gut microflora may contribute to fat storage, as well as the occurrence of gestational insulin resistance, is blocking the expression of the fasting-induced adipose factor. SCFAs, in particular propionic acid via GPR, determine the development and metabolic programming of the fetus in pregnant women. The mechanisms regulating lipid metabolism during pregnancy are similar to those found in obese people and those with impaired microbiome and its metabolites. The implications of SCFAs and metabolic disorders during pregnancy are therefore critical to maternal health and neonatal development. In this review paper, we summarize the current knowledge about SCFAs, their potential impact and possible mechanisms of action in relation to maternal metabolism during pregnancy. Therefore, they constitute a contemporary challenge to practical nutritional therapy. Material and methods: The PubMed database were searched for “pregnancy”, “lipids”, “SCFA” in conjunction with “diabetes”, “hypertension”, and “microbiota”, and searches were limited to work published for a period not exceeding 20 years in the past. Out of 2927 publication items, 2778 papers were excluded from the analysis, due to being unrelated to the main topic, conference summaries and/or articles written in a language other than English, while the remaining 126 publications were included in the analysis.

Placental lipid metabolism in preeclampsia

OBJECTIVES

The current study examines the placental and maternal lipid profile and expression of genes involved in placental lipid metabolism in women with preeclampsia.

METHODS

The current study includes normotensive control women (n = 40) and women with preeclampsia (n = 39). Preeclampsia women were further classified into women delivering at term preeclampsia (T-PE; n = 15) and preterm preeclampsia (PT-PE; n = 24).

RESULTS

There were no significant differences in maternal lipid profile between the T-PE and normotensive control groups. Maternal plasma VLDL (P < 0.05) and ratios of total cholesterol : HDL (P < 0.05), atherogenic index [log (triglycerides/HDL)] (P < 0.01) and apolipoprotein B : apolipoprotein A (P < 0.05) were higher in the PT-PE group as compared with the normotensive control group. Placental total cholesterol and HDL levels were higher (P < 0.05) in the T-PE as compared with the normotensive control group. Higher placental triglycerides (P < 0.05) were observed in PT-PE group compared with T-PE group. Placental mRNA levels of peroxisome proliferator activated receptor α, carnitine palmitoyl transferase-1, cluster of differentiation 36 and lipoprotein lipases were lower (P < 0.05) in the PT-PE than normotensive control group. A negative association of mRNA levels of peroxisome proliferator activated receptor α (r = -0.246, P = 0.032; r = -0.308, P = 0.007, respectively), carnitine palmitoyl transferase-1 (r = -0.292, P = 0.011; r = -0.366, P = 0.001), lipoprotein lipases (r = -0.296, P = 0.010; r = -0.254, P = 0.028) with SBP and DBP was observed. There was a positive association of placental triglycerides (r = 0.244, P = 0.031) with DBP.

CONCLUSION

Women with preeclampsia exhibit higher lipid : lipoprotein ratios suggesting an atherogenic state particularly in women delivering preterm. Lower expression of genes involved in placental fatty acid oxidation and transport was also observed in preeclampsia.

LIPG: an inflammation and cancer modulator

Endothelial lipase (LIPG/EL) performs fundamental and vital roles in the human body, including cell composition, cytokine expression, and energy provision. Since LIPG predominantly functions as a phospholipase as well as presents low levels of triglyceride lipase activity, it plays an essential role in lipoprotein metabolism, and involves in the metabolic syndromes such as inflammatory response and atherosclerosis. Cytokines significantly affect LIPG expression in endothelial cells in many diseases. Recently, it is suggested that LIPG contributes to cancer initiation and progression, and LIPG attached increasing importance to its potential for future targeted therapy.

Placental lipoprotein lipase DNA methylation alterations are associated with gestational diabetes and body composition at 5 years of age

Gestational diabetes mellitus (GDM) is associated with obesity in childhood. This suggests that consequences of in utero exposure to maternal hyperglycemia extend beyond the fetal development, possibly through epigenetic programming. The aims of this study were to assess whether placental DNA methylation (DNAm) marks were associated with maternal GDM status and to offspring body composition at 5 years old in a prospective birth cohort. DNAm levels were measured in the fetal side of the placenta in 66 samples (24 from GDM mothers) using bisDNA-pyrosequencing. Anthropometric and body composition (bioimpedance) were measured in children at 5 years of age. Mann-Whitney and Spearman tests were used to assess associations between GDM, placental DNAm levels at the lipoprotein lipase (LPL) locus and children's weight, height, body mass index (BMI), body fat, and lean masses at 5 years of age. Weight, height, and BMI z-scores were computed according to the World Health Organization growth chart. Analyses were adjusted for gestational age at birth, child sex, maternal age, and pre-pregnancy BMI. LPL DNAm levels were positively correlated with birth weight z-scores (r = 0.252, P = 0.04), and with mid-childhood weight z-scores (r = 0.314, P = 0.01) and fat mass (r = 0.275, P = 0.04), and negatively correlated with lean mass (r = -0.306, P = 0.02). We found a negative correlation between LPL DNAm and mRNA levels in placenta (r = -0.459; P < 0.001), which highlights the regulation of transcriptional activity by these epivariations. We demonstrated that alterations in fetal placental DNAm levels at the LPL gene locus are associated with the anthropometric profile in children at 5 years of age. These findings support the concept of fetal metabolic programming through epigenetic changes.

Lipoprotein lipase and lipid profiles in plasma and placenta from normal pregnancies compared with patients with intrahepatic cholestasis of pregnancy

OBJECTIVE

To analyse lipoprotein lipase (LPL) expression and lipid levels in placenta and plasma of patients with intrahepatic cholestasis of pregnancy (ICP) and normal pregnancies.

METHODS

This prospective study included 30 patients with ICP and 30 gestational-age-matched pregnancies without any complications. Enzyme-linked immunosorbent assays were used to investigate plasma LPL levels from 28 weeks of gestation, at 4-weekly intervals, to 38 weeks of gestation, and data were assessed longitudinally. Immunohistochemistry, Western blotting and real-time polymerase chain reaction were used to detect placental LPL expression and activity. Placental triglyceride and total cholesterol levels were also analysed. The clinical data related to ICP and lipid profiles were collected retrospectively.

RESULTS

Plasma LPL concentration increased with gestational age in both groups, but the increase was limited in the ICP group. Immunohistochemistry revealed LPL staining mainly in syncytiotrophoblasts, and 3,3'-diamino-benzidine tetrahydrochloride wt% was lower in ICP placenta compared with normal placenta (p<0.01). LPL protein and mRNA expression in ICP placenta were significantly lower than in normal placenta (p<0.01). LPL activity was not significantly different in both groups. Correlation analysis indicated that the plasma LPL level was negatively associated with the corresponding concentration of total bile acid (r=-0.57) in the ICP group.

CONCLUSION

Reduced LPL expression in placenta, limited increase in LPL level in maternal plasma, and abnormal lipid profiles were found in patients with ICP. LPL was possibly related to ICP by participating abnormal lipid metabolism.