Protein pathways working in human follicular fluid: the future for tailored IVF?

The human follicular fluid (HFF) contains molecules and proteins that may affect follicle growth, oocyte maturation and competence acquiring. Despite the numerous studies, an integrated broad overview on biomolecular and patho/physiological processes that are proved or supposed to take place in HFF during folliculogenesis and oocyte development is still missing. In this review we report, for the first time, all the proteins unambiguously detected in HFF and, applying DAVID (Database for Annotation, Visualization and Integrated Discovery) and MetaCore bioinformatic resources, we shed new lights on their functional correlation, delineating protein patterns and pathways with reasonable potentialities for oocyte quality estimation in in vitro fertilisation (IVF) programs. Performing a rigorous PubMed search, we redacted a list of 617 unique proteins unambiguously-annotated as HFF components. Their functional processing suggested the occurrence in HFF of a tight and highly dynamic functional-network, which is balanced by specific effectors, primarily involved in extracellular matrix degradation and remodelling, inflammation and coagulation. Metalloproteinases, thrombin and vitamin-D-receptor/retinoid-X-receptor-alpha resulted as the main key factors in the nets and their differential activity may be indicative of ovarian health and oocyte quality. Despite future accurate clinical investigations are absolutely needed, the present analysis may provide a starting point for more accurate oocyte quality estimation and for defining personalised therapies in reproductive medicine.