Obesity Modulates Inflammation and Lipid Metabolism Oocyte Gene Expression: A Single-Cell Transcriptome Perspective

Abstract

Context: It is hypothesized that obesity adversely affects the ovarian environment, which can disrupt oocyte maturation and embryonic development.

Objective: This study aimed to compare oocyte gene expression profiles and follicular fluid (FF) content from overweight/obese (OW) women and normal-weight (NW) women who were undergoing fertility treatments.

Design: Using single-cell transcriptomic analyses, we investigated oocyte gene expression using RNA sequencing.

Patients or other participants: Eleven OW women and 13 NW women undergoing fertility treatments were enrolled.

Main outcome measures: Oocyte messenger RNA profiles as well as serum and FF hormone and lipid levels were assessed.

Results: OW women had significantly higher body mass index, body fat percentage, and serum homeostatic model assessment-insulin resistance index compared with NW women (P < 0.01). Serum leptin and C-reactive protein (CRP) levels as well as FF leptin, CRP, and triglyceride levels were increased (P < 0.05) in OW compared with NW women. Oocytes from OW women had increased expression of proinflammatory (CXCL2; P = 0.071) and oxidative stress-related (DUSP1; P = 0.051) genes but had decreased expression of GAS7 (fat metabolism; P = 0.065), TXNIP (oxidative stress; P = 0.055), and transcription factors ID3 (P = 0.075) and TWIST1 (P = 0.099) compared with NW women.

Conclusions: These findings provide evidence for the significant influence of body composition on oocyte transcript abundance in women undergoing hormonal induction to retrieve oocytes. They further identify the potential for maternal diet to influence oocyte gene expression. The preconception period is, therefore, an important window of opportunity to consider for lifestyle interventions.

Trial registration: ClinicalTrials.gov NCT01480024.

Copyright © 2017 Endocrine Society

Figures

Figure 1.

FF levels of triglycerides, leptin, and CRP from NW (N = 13, black bars) and OW (N = 11, gray bars) women. Data are represented as mean ± SEM. A significant difference between groups was set at P < 0.05 (*) using the Mann-Whitney U nonparametric tests.

Figure 2.

(a) Scatterplots of differentially expressed genes between NW and OW groups identified on the basis of P value ≤0.05 and ±twofold change with SeqMonk. Selected genes for RT-qPCR confirmation are circled in red. (b) Hierarchical clustering of reads per kilobase per million mapped reads values using a function in the FactoMineR package of all genes showing grouping of individual samples that belong to different oocyte maturation stages. (c) Venn diagram for differentially expressed genes between maturation stages.

Figure 3.

Relative gene expression for selected genes using the isolated cDNA from the RNA-Seq analyses to conduct RT-qPCR for each oocyte maturation stage (NW women, white bars; OW women, black bars). All values were normalized using a geometric mean for glyceraldehyde 3-phosphate dehydrogenase and β-actin mRNA expression as mean fold change relative to NW women for GV, MI, and MII oocytes. Data are expressed as mean ± SEM. Significant differences between groups was set at P ≤ 0.05 using the Mann-Whitney U nonparametric test. Variation in sample size is due to undetectable expression by RT-qPCR. CXCL2, chemokine (C-X-C motif) ligand 2 (NW = 5, OW = 3); DUSP1, dual specificity protein phosphatase 1 (NW = 8, OW = 5); GAS7, growth arrest specific 7 (NW = 8, OW = 5); ID3, inhibitor of DNA binding 3, HLH protein (NW = 10, OW = 5); TXNIP, thioredoxin interacting protein (NW = 5, OW = 5); TWIST1, Twist family bHLH transcription factor 1 (NW = 10, OW = 5).