Transferrin Insufficiency and Iron Overload in Follicular Fluid Contribute to Oocyte Dysmaturity in Infertile Women With Advanced Endometriosis

Abstract

<b>Purpose:</b> To screen out specific protein with different concentration in follicular fluid from advanced endometriosis and determine its direct effect on mouse oocytes matured <i>in vitro</i>. <b>Methods:</b> FF samples were obtained from 25 patients (EMS group, <i>n</i> = 15; control group, <i>n</i> = 10) to screen the differential proteins by using iTRAQ Labeling and 2D LC-MS. Transferrin (TRF) in was found significantly decreased in EMS group, which was verified using ELISA in enlarged FF samples (EMS group, <i>n</i> = 31; control group, <i>n</i> = 27). The contents of ferric ion in FFs were detected by ELISA and TRF saturations were calculated in two groups. Germinal vesicle (GV) oocytes of mouse were maturated <i>in vitro</i> interfered with the FFs in five groups, whose concentrations of TRF were modulated, and maturation <i>in vitro</i> rates were compared among groups. <b>Results:</b> The reduced concentration of TRF with three analogs and increased concentration of ferric ion were found in the FF of the EMS group (<i>p</i> < 0.05). The numerical values of TSAT was 54.8% in EMS group, indicating iron overload in the FF. The EMS-FF showed significantly decreased maturation <i>in vitro</i> rate (<i>p</i> < 0.05) of mouse oocytes, which was improved with the supplementation of TRF, compared with the control-FF. The effect was blocked by the TRF antibody (<i>p</i> < 0.05). <b>Conclusions:</b> Being aware of the relatively small sample size, our results possibly suggest that TRF insufficiency and iron overload in FF from advanced EMS contribute to oocytes dysmaturity, which may be a cause of EMS-related infertility.