P-677 fasting-mimicking diet delays ovarian aging by modulating immune cells and enhancing glycocholic acid levels

Abstract Study question Does fasting-mimicking diet (FMD) alleviate ovarian aging in mice, and what roles do gut and serum metabolites play in this process? Summary answer FMD improves ovarian function in aged mice by increasing glycocholic acid (GCA), which reduces T helper 1 (Th1) cells and inflammation. What is known already Dietary interventions, including fasting and fasting-mimicking diets (FMDs), affect ovarian function by influencing follicle development, endocrine balance, and age-related decline. FMDs offer advantages over other fasting strategies, being safer and more sustainable while maintaining benefits such as reduced inflammation and metabolic rejuvenation. FMD impacts gut and serum metabolites, which play critical roles in ovarian development, hormonal balance, and aging processes. Gut metabolites like bile acids influence immune regulation, inflammation, and mitochondrial function, essential for ovarian health. However, the effects of FMD on ovarian aging and the roles of metabolites remain unclear. Study design, size, duration Middle-aged mice underwent an 8-week FMD protocol. Ovarian function was evaluated by follicular counts, retrieved oocytes, embryonic development, and offspring. Cellular mechanisms were investigated using single-cell RNA sequencing (scRNA-seq) of ovarian cells. Metabolomic analysis of serum and gut samples was performed to identify FMD-induced metabolite changes. Selected metabolites were administered to mice to assess effects on ovarian function and oocyte development. In vitro experiments evaluated metabolite impact on immune cell differentiation and function. Participants/materials, setting, methods Ovarian function was assessed in FMD-treated middle-aged mice. Histology quantified follicles, while IVF evaluated embryonic development. scRNA-seq analyzed ovarian cell populations, focusing on immune cells. Metabolomics identified key FMD-altered serum and gut metabolites. GCA, a major differential metabolite, was administered to mice, followed by ovarian function and oocyte development evaluation, and scRNA-seq analysis of GCA’s effect on ovarian immune cells. In vitro, GCA’s impact on Th1 differentiation, T-bet activity, and IFNG expression was examined. Main results and the role of chance FMD significantly improved ovarian function in middle-aged mice, with increased mature oocyte yield, improved embryonic development, and enhanced fertility. scRNA-seq revealed a reduction in ovarian Th1 cells and inflammation-associated gene signatures. Metabolomic analysis identified GCA as a key FMD-induced metabolite, with elevated GCA levels observed in the serum and ovaries of FMD-treated mice. GCA treatment alone improved ovarian function and reduced Th1 cell numbers in middle-aged mice. Ovarian scRNA-seq confirmed the reduction of Th1 cells and their associated proinflammatory signals in GCA-treated mice. In vitro, GCA inhibited T-bet activation, leading to reduced IFNG expression and impaired Th1 cell differentiation, suggesting an immune-modulatory mechanism through which GCA protects against ovarian aging. Limitations, reasons for caution This study primarily focused on middle-aged mice, and its findings may not fully apply to other age groups or humans. While the study demonstrated a clear link between GCA and reduced Th1 cells, the full range of mechanisms by which FMD and GCA influence ovarian aging requires further exploration. Wider implications of the findings FMD and its metabolite, GCA, show potential therapeutic effects on ovarian aging by modulating immune cell activity, providing insights into dietary interventions for improving ovarian health and fertility in aging populations. Future studies should investigate applicability in humans and explore additional FMD-influenced metabolites. Trial registration number No