Transforming growth factor-β1 and its receptor soluble endoglin are altered in polycystic ovary syndrome during controlled ovarian stimulation

Objective: To evaluate the relationship between transforming growth factor (TGF)-β1 and its receptor, soluble endoglin (sENG), in the serum and follicular fluid of women with polycystic ovarian syndrome (PCOS) compared with that of non-PCOS normal ovulating women during controlled ovarian stimulation (COS). Design: Prospective case-control study. Setting: Academic-affiliated assisted reproductive technology unit. Patient(s): Fourteen PCOS and 14 matched non-PCOS control women undergoing COS. Intervention(s): Serum was collected on day 3 (baseline), day of hCG, and day of retrieval. Follicular fluid (FF) was collected on day of oocyte retrieval. ELISA was performed to determine TGF-β1 and sENG protein levels. Main Outcome Measure(s): Serum and FF levels of TGF-β1 and sENG. Result(s): Serum TGF-β1 did not change significantly during COS but was increased in PCOS compared with non-PCOS women on day 3 and days of hCG administration and oocyte retrieval. Serum sENG increased after hCG administration only in the non-PCOS control group. In addition, serum sENG was decreased in PCOS compared with non-PCOS control women on the days of hCG and retrieval. Accordingly, the bioavailability of TGF-β1 (TGF-β1/sENG ratio) was increased in women with PCOS compared with non-PCOS controls at all three time points. No differences in either factor were noted in FF between groups. Conclusion(s): The increased TGF-β1 bioavailability in PCOS is not only due to increased TGF-β1 levels but also to decreased levels of its receptor, sENG. These data suggest that increased TGF-β1 bioavailability may contribute to the pathogenesis of PCOS and its increased risk for ovarian hyperstimulation.