Metabolomic analysis of follicular fluid in women with unexplained infertility.
This study highlights metabolic disruptions in follicular fluid associated with unexplained infertility, but findings are preliminary and require further validation.
Where it sits
this study against the rest of the kpv corpusSummary and findings
This study investigated the follicular fluid metabolome of 20 women undergoing IVF, comparing 10 with unexplained infertility (UI) to 10 with male factor infertility. Metabolomic profiling identified 12 significantly decreased metabolites and one increased metabolite in women with UI. The study also noted reduced levels of follicular 25-hydroxyvitamin D despite uniform oral supplementation.
Abstract
Unexplained infertility (UI) affects ∼10% of infertile couples, yet standard diagnostic protocols fail to identify a cause. Follicular fluid (FF), which supports oocyte development, contains metabolites that may reflect underlying molecular disturbances. In this exploratory study, we investigated the FF metabolome of women with UI and compared it with controls to explore metabolic alterations associated with UI. FF was collected during oocyte retrieval from 20 women undergoing IVF (ten with UI, ten with male factor infertility), matched for age, BMI, stimulation, and fertilization protocols. Metabolomic profiling was performed using hydrophilic interaction and reversed-phase liquid chromatography coupled to Q-TOF-MS/MS, followed by metabolite identification (XCMS Online and MetaboAnalyst) and KEGG pathway analysis. Approximately 2000 features were detected. Differential metabolites were identified by OPLS-DA (VIP > 2) and validated using univariate metrics such as fold change (|log<sub>2</sub>FC| > 1), statistical significance (<i>p</i> < 0.05), and ROC analysis (AUC > 0.8). Twelve metabolites, including diacylglycerols, phosphatidic acids, vitamin D3 derivatives (VitD3-glucosiduronate, 1α-hydroxy-2β-(5-hydroxypentoxy)-VitD3), asparaginyl-asparagine, 3α-hydroxy-6-oxo-5β-cholan-24-oic acid, Leu-Pro-Ala-Ser-Phe, triacylglycerols, phosphatidylcholine, and lactosyl-ceramide were significantly decreased, while Ile-Lys-Val-Val was increased in women with UI. Pathway analysis highlighted disruptions in glycerophospholipid, glycerolipid, steroid, and linoleic acid metabolism. Consistent with the untargeted findings, targeted analysis demonstrated significantly reduced levels of follicular 25-hydroxyvitamin D [25(OH)D] in women with UI despite uniform oral supplementation, indicating dysregulated follicular vitamin D availability. Whilst the study was limited by sample size, the metabolome analysis was performed in triplicate for each sample, thus providing preliminary insights into the metabolic disruptions in FF from women with UI.
Background
Unexplained infertility (UI) affects approximately 10% of infertile couples, and existing diagnostic protocols often fail to identify a cause. Follicular fluid (FF) plays a critical role in oocyte development and may contain metabolites that reflect underlying molecular disturbances. This study aims to explore metabolic alterations in FF associated with UI compared to controls.
Methods
This exploratory study involved 20 women undergoing IVF, with 10 having UI and 10 with male factor infertility. Participants were matched for age, BMI, stimulation, and fertilization protocols. Metabolomic profiling was conducted using hydrophilic interaction and reversed-phase liquid chromatography coupled to Q-TOF-MS/MS, with analysis performed in triplicate for each sample.
Results
The primary endpoint identified twelve metabolites that were significantly decreased in women with UI, alongside one metabolite that was increased. Statistical significance was determined with a p-value of less than 0.05. Pathway analysis indicated disruptions in various metabolic pathways, including glycerophospholipid and steroid metabolism.
Interpretation
The findings suggest metabolic disruptions in the follicular fluid of women with UI, aligning with previous literature on metabolic alterations in infertility. However, the clinical significance of these findings remains uncertain due to the small sample size and potential confounding factors. Further research is needed to validate these results and understand their implications for clinical practice.
Key findings
- Twelve metabolites significantly decreased in women with UI, including diacylglycerols and phosphatidic acids.
- Ile-Lys-Val-Val was increased in women with UI.
- Statistical significance was defined as p < 0.05.
- Approximately 2000 features were detected during metabolomic profiling.
- Pathway analysis highlighted disruptions in glycerophospholipid and steroid metabolism.
- Follicular 25-hydroxyvitamin D levels were significantly reduced in women with UI.
Limitations
- small sample size of n=20
- exploratory study design limits generalizability
- potential confounding factors not fully addressed
- no long-term follow-up to assess clinical outcomes