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Small RNA sequencing of term whole placenta from normal weight and obese pregnancies

ABSTRACT: Context: An increase in maternal insulin resistance (IR) during pregnancy is essential for normal fetal growth. The mechanisms underlying this metabolic adaptation to pregnancy are poorly understood. Placenta factors are believed to instigate and maintain these metabolic changes, as IR decreases shortly after delivery. Methylation of placental gene loci that are common targets for miRNAs, are associated with maternal IR. Objective: We hypothesized that placental miRNAs targeting methylated loci are associated with maternal IR during late pregnancy. Methods: Placental miRNA expression was measured via small RNA-sequencing in a subset of 40 placentas selected by maternal pre-gravid BMI and neonatal adiposity. Results: Median maternal age was 27.5 years, with a median pre-pregnancy BMI of 24.7 kg/m2, and median HOMA-IR of 2.9. Among the five selected miRNA, near delivery maternal HOMA-IR correlated with the placental expression of miRNA-371b-3p (r=0.25; p=0.008) and miRNA-3940-3p (r=0.32; p=0.0004) across the 132 individuals. After adjustment for confounding variables, placental miRNA-3940-3p expression remained significantly associated with HOMA-IR (β=0.16; p=0.03). Conclusion: Placental miRNA may have an autocrine or paracrine effect - regulating placental genes which play a role in modulating maternal IR.

ORGANISM(S): Homo sapiens

PROVIDER: GSE169523 | GEO | 2023/03/01

REPOSITORIES: GEO

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Project description:The role of extracellular vesicles (EVs), specifically exosomes, in intercellular communication likely plays a key role in placental orchestration of pregnancy and maternal immune sensing of the fetus. While murine models are powerful tools to study pregnancy and maternal-fetal immune interactions, in contrast to human placental exosomes, the content of murine placental and pregnancy exosomes remains largely understudied. Using a recently developed in vitro culture technique, murine trophoblast stem cells derived from B6 mice were differentiated into syncytial-like cells. EVs from the conditioned media, as well as from pregnant and non-pregnant sera, were enriched for exosomes. The RNA composition of these murine trophoblast-derived and pregnancy-associated exosome-enriched-EVs (ExoE-EVs) was determined using RNA-sequencing analysis and expression levels confirmed by qRT-PCR. Differentially abundant miRNAs were detected in syncytial differentiated ExoE-EVs, particularly from the X chromosome cluster (mmu-miR-322-3p, mmu-miR-322-5p, mmu-miR-503-5p, mmu-miR-542-3p, and mmu-miR-450a-5p). These were confirmed to be increased in pregnant mouse sera ExoE-EVs by qRT-PCR analysis. Interestingly, fifteen miRNAs were only present within the pregnancy-derived ExoE-EVs compared to non-pregnant controls. Mmu-miR-292-3p and mmu-miR-183-5p were noted to be some of the most abundant miRNAs in syncytial ExoE-EVs and were also present at higher levels in pregnant versus non-pregnant sera ExoE-EVs. The bioinformatics tool, MultiMir, was employed to query publicly available databases of predicted miRNA-target interactions. This analysis reveals that the X-chromosome miRNAs are predicted to target ubiquitin-mediated proteolysis and intracellular signaling pathways. Knowing the cargo of placental and pregnancy-specific ExoE-EVs as well as the predicted biological targets informs studies using murine models to examine not only maternal-fetal immune interactions but also the physiologic consequences of placental-maternal communication.

Project description:Background: Maternal pre-pregnancy BMI is a critical factor influencing the composition of breast milk. Breast milk has abundant extracellular vesicles (EVs) containing various biological molecules (cargo), including miRNAs. EVs are not degraded in the gastrointestinal system and circulation; thus, breast milk EVs (bEVs) interact with other organs in breastfed infants and modify the gene expression of recipient cells using miRNAs. In maternal obesity, miRNAs in bEVs are deregulated, which might be associated with adverse health outcomes in infants. In this study, we examined 798 miRNAs to determine which miRNAs are altered in the bEVs of obese mothers and their potential impact on breastfed infants. Methods: We recruited healthy nursing mothers who were either obese (BMI≥30) or lean (BMI<25) based on their pre-pregnancy BMI, and delivered a singleton baby in the prior six months. EVs were isolated from breast milk with ultracentrifugation. bEV characteristics were examined by flow cytometry and fluorescence imaging of EV markers. A total of 798 miRNAs were screened using a NanoString human miRNA panel to find deregulated miRNAs in bEVs of obese mothers compared to lean mothers. Results: We included 65 nursing mothers: 47 lean and 18 obese mothers based on pre-pregnancy BMI. After bEV isolation, we confirmed the expression of general EV markers. Out of 37 EV markers, CD326 was the most highly expressed marker in bEVs. From miRNA analysis using NanoString, we found that the most abundant miRNAs include miR-30b-5p, miR-494-3p, and let-7 families, and the list of top 10 miRNAs was not different between lean and obese mothers. Target genes of the top 10 miRNAs were associated with the EGFR, ErbB, and FoxO signaling pathway. Nineteen miRNAs were deregulated in bEVs of obese mothers (adjusted p < 0.05 cut-off), including miR-575, miR-548g-3p, miR-582-3p, and miR-652-5p. The target genes of these miRNAs are associated with lipid metabolism, inflammatory diseases, and nervous/cardiovascular system development. Conclusion: In this study, we demonstrated altered miRNAs in bEVs of obese mothers and identified the pathways of their potential target genes. Our findings will provide insight for future studies investigating the role of bEVs in breastfed infants.

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Small RNA sequencing of term whole placenta from normal weight and obese pregnancies

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