P-667 GPD1L-mediated glycerophospholipid metabolism dysfunction in women with diminished ovarian reserve: Insights from pseudotargeted metabolomic analysis of follicular fluid

Abstract Study question What are the alterations in the metabolic profile of follicular fluid in patients with diminished ovarian reserve (DOR) compared to healthy women? Summary answer The metabolic signature of follicular fluid reveals a downregulation of glycerophospholipid metabolism pathway including PA, PC, lysoPC and lysoPE in DOR patients. What is known already Follicular fluid serves as the microenvironment for follicular growth and oocyte maturation, facilitating materials and energy exchange between oocytes and surrounding cells. An in-depth understanding of the metabolic state of follicular fluid will help us uncover the key biological processes involved in ovarian aging. Though various metabolomics analyses have revealed that metabolite alternations are associated with DOR, their specific roles in granulosa cell dysfunction and follicular atresia still need to be explored. Study design, size, duration This study includes follicular fluid samples collected from 60 DOR patients and 60 patients with normal ovarian reserve (NOR) undergoing in vitro fertilization and embryo transfer (IVF-ET). Each group was then divided into two subgroups (30 patients for young and 30 for aged groups) based on an age of 35. Participants/materials, setting, methods The pseudotargeted metabolic analysis of follicular fluids of matured follicles was conducted and the intensities of captured metabolites were utilized for further bioinformatic analysis. The correlation between the significant differential metabolites and ovarian function of patients and their clinical outcomes were analyzed. Then, in vitro experiments were performed to investigated the function of genes that mainly regulate the metabolism pathway. Main results and the role of chance As a result, total of 608 metabolites were identified in all follicular fluid samples. 65 significant differential metabolic features were identified between the NOR and DOR groups, whereas 48 differential metabolic features were noted between the young and aged groups. Then, as revealed by KEGG analysis, glycerophospholipid metabolism was the most enriched pathway in DOR patients. The levels of several key metabolites in glycerophospholipid metabolism pathway including PA, PC, lysoPC and lysoPE were positively correlated with anti-Müllerian hormone (AMH), antral follicle count (AFC) and retrieved oocytes number while negatively correlated with female age. We also identified the reduced glycerol-3-phosphatedehydrogenase-1-like (GPD1L) expression levels in granulosa cells of DOR patients, which encodes the key enzyme in the glycerophospholipid metabolism pathway. Furthermore, we validated that the downregulation of GPD1L participates in ovarian aging by inducing granulosa cell apoptosis and mitochondria dysfunction, as well as inducing follicular atresia and impairing oocyte quality. Limitations, reasons for caution The validity of those differential metabolites we identified in this study as clinical diagnostic biomarkers still needs to be confirmed in large-scale studies. And the effect of GPD1L and glycerophospholipid metabolic pathway dysfunction on follicular development still requires in-depth mechanistic excavation. Wider implications of the findings Our study identified potential novel biomarkers of DOR diagnosis and pave the way for a new theoretical basis for understanding the pathogenesis, treatment and intervention of DOR. Trial registration number No