Changes in bovine follicular fluid cytokine profile associated with oocyte developmental competence

This work aimed to evaluate the cytokine profile of bovine follicular fluid (FF) enclosing oocytes with contrasting developmental competence (Experiment 1) to identify competence-associated biomarkers. The FF was collected from individual 2-4 mm follicles of abattoir-derived ovaries, diluted in PBS, centrifuged, and stored at - 80 °C. At the same time, the corresponding oocytes were individually matured, fertilized, and cultured. On day 8 of culture, the stored FF samples were retrospectively assigned to three different categories corresponding to: oocytes that reached the blastocyst stage (B), cleaved oocytes (C), and uncleaved oocytes (U). A panel of 30 cytokines was analyzed in sixteen individual follicles per category using the Quantibody® Bovine Cytokine Array 30 kit. Ttumor necrosis factor-α (TNF-α) was higher (P < 0.05) in the B group than in the U group, with similar values recorded in the C group. The concentration of Acidic Fibroblast Growth Factor (aFGF) was reduced (P < 0.01) in the B group compared to the C and U groups. The B group had lower (P < 0.05) levels of Interleukin-15 (IL-15) than the C group, with no significant difference compared with the U group. The Interferon Gamma-Induced Protein 10 (IP-10) levels were lower (P < 0.05) in both the B and C groups compared to the U group. A decrease in Interleukin-17a (IL-17a) was observed only in the C group compared to the other groups. Another objective of the present study was to assess whether including TNF-α, which showed significantly higher abundance (P < 0.05) in FF corresponding to competent oocytes, in a simulated physiological oocyte maturation system (SPOM) would improve embryo yields (Experiment 2). Therefore, bovine cumulus-oocyte complexes (COCs) were matured in SPOM with 0, 0.28 ng/mL, 0.46 ng/mL, and 1 ng/mL TNF-α, fertilized, and cultured to the blastocyst stage. However, TNF-α supplementation during SPOM did not improve embryo development compared with the control. In conclusion, the cytokine profile of FF varied according to oocyte developmental competence, enabling the identification of TNF-α as a potential positive marker and aFGF, IP-10, and IL-15 as negative markers of competence.