Obesity Affects IVF Outcomes and Mevalonic Acid Rescues the Side Effects of Statins on Follicle Growth

Abstract

The accelerating trend of obesity in women of childbearing age has become a significant issue in personal health, female fecundity, and offspring development. Simvastatin (SV) is a statin commonly prescribed oral agent for lipid-lowering therapy; however, its applicability in reproductively active women remains controversial. In this study, through clinical data analysis, we further confirmed that obesity reduces in vitro fertilization pregnancy success, with significant decreases in the number of retrieved oocytes, mature oocytes, and cleavage embryos. We found SV inhibited follicle development cultured in vitro. Based on our previously reported metabolomics data, mevalonic acid (MVA) was found to be a key metabolite in follicular development. In our in vitro follicle culture system, we demonstrated that the supplement of MVA in SV-added follicles recovered to grow similar to the untreated blank group, indicating the rescue effect of potential reproductive toxicity of SV. Both the downstream metabolites cholesterol and geranylgeraniol partially attenuated SV-induced apoptosis elevation and proliferation suppression in KGN cells. RNA sequencing results suggested that this rescue effect may be mediated through the TNF, PI3K-Akt, and JAK-STAT pathways. Our study shed light upon clinical practice for women of childbearing age who were treated with statins and might contribute to better health management in obesity populations.

Keywords: follicular development; in vitro follicle culture; lipid metabolism; mevalonic acid; obesity; simvastatin.

FIGURE 1

(A) Correlations between BMI and clinical parameters. (B) Representative images of follicular growth on Days 0, 2, 4, and 6 in each group (magnification, 40×; scale bar, 100 μm). There were at least 40 follicles per group. (C) In vitro follicle growth curve. (D) Growth diameters of surviving follicles (the diameter on Day 6 minus that on Day 0). (E) Survival rate of follicles in different groups. Results presented as the mean ± SEM. Different letters in superscript (a, b, c) indicate significant differences between groups (p < 0.05).

FIGURE 2

(A) Relative MVA content in FF at different developmental stages. (B) Follicle size: the area under the ROC curve for MVA was 0.9778 (***p < 0.001); C Representative images of follicle growth in vitro on Days 0, 2, 4, and 6 in different groups (magnification, 40×; scale bar, 100 μm). There were at least 40 follicles per group. (D) Growth curves of follicle growth at different MVA concentrations in the rescue experiment. (E) Concentrations of estradiol in the follicular culture medium on Days 2,4 and 6. (F) Follicle diameters on Day 6 in different groups. (G) Survival rates of follicles in different groups. (H) Antrum formation rates of follicles on Day 6 in different experiments. Results are presented as the mean ± SEM. Different superscript letters (a, b, c) indicate significant differences between groups (p < 0.05).

FIGURE 3

(A) The apoptosis of KGN cells in each group was detected using Annexin V/PI staining. (B) Histogram of apoptosis of KGN cells in each group. (C) Cell proliferation was measured at the indicated time points using Cell Counting Kit‐8. Results are presented as the mean ± SEM. Different superscript letters (a, b, c) indicate significant differences between groups (p < 0.05).

FIGURE 4

(A) Hierarchical cluster analysis of DEGs identified by transcriptomic analysis of GCs. Blue, white, and red representing gradients gene expression levels, with blue representing low and red representing high. (B) Heatmap showing DEGs between the SM and S groups. Color coding as in (A). Horizontal bars represent genes with columns representing samples. (C) GO annotations of DEGs in the SM versus S groups. The horizontal coordinate represents DEG annotations, and the left and right vertical coordinates indicate the proportions of up‐and down‐regulated DEGs. (D) The q‐value distribution map of enriched KEGG pathways. Colors indicate q‐values. (E) KEGG enrichment of DEGs, showing the top 10 pathways in the SM versus S groups. The enrichment factor indicates the number of DEGs relative to the overall number of genes. Dot sizes represent gene numbers in the pathways, with dot colors indicating q‐values; F RT‐qPCR verification of the expression of eight DEGs. Results are presented as the mean ± SEM.*p < 0.05, **p < 0.01, ***p < 0.001.