Bile acids in follicular fluid: potential new therapeutic targets and predictive markers for women with diminished ovarian reserve.

Objective: To investigate the changes in bile acid (BA) metabolites within the follicular fluid (FF) of patients with diminished ovarian reserve (DOR) and to identify novel diagnostic markers that could facilitate early detection and intervention in DOR patients.

Design: A total of 182 patients undergoing assisted reproductive technology (ART) were enrolled and categorized into the normal ovarian reserve (NOR) group (n = 91) or the DOR group (n = 91) to measure BA levels in FF. To identify the changes in granulosa cells (GCs), we collected GCs from an additional 7 groups of patients for transcriptome sequencing.

Setting: Reproductive medicine center within a hospital and university research laboratory.

Population: A total of 182 patients undergoing assisted reproductive technology were enrolled and categorized into the NOR group (n = 91) or the DOR group (n = 91).

Methods: In this study, BA metabolites in FF of DOR and NOR patients were analyzed in detail by targeted metabolomics, and the correlation between BA levels in FF and clinical indicators was discussed. Then, we constructed a diagnostic model for DOR using the random forest algorithm based on five different BAs. Additionally, we performed a functional enrichment analysis on differentially expressed genes (DEGs) in GCs from both DOR and NOR patients.

Main outcome measures: BA levels in FF and their correlation with clinical indicators; the areas under the curve (AUCs) of the random forest diagnostic model for DOR; and the DEGs and corresponding functional enrichment results of GC RNA analysis.

Result (s): The levels of lithocholic acid, chenodeoxycholic acid, ursodeoxycholic acid, deoxycholic acid and cholic acid in FF of DOR group were lower than those of NOR group. And significant reductions in total, primary, secondary, and unconjugated BA levels were observed in the DOR group. The above five BAs levels were closely related to indicators of ovarian reserve. The AUC of the diagnostic model based on the above five BAs was 0.964. Based on transcriptome sequencing data from two groups of GCs, a total of 482 up-regulated and 654 down-regulated DEGs were identified. Gene ontology analysis revealed that the metabolic and biosynthetic processes of fatty acids, steroids, and cholesterol were enriched in these DEGs, whereas Kyoto Encyclopedia of Genes and Genomes analysis indicated enrichment of fatty acid and ovarian steroidogenesis.

Conclusion(s): The levels of multiple BA metabolites in FF are significantly lower than those in patients with DOR and are closely related to the evaluation of ovarian reserve function.