Bone Morphogenetic Proteins are Significantly Reduced in the Follicular Fluid of Han Chinese Polycystic Ovary Syndrome Patients

Abstract

Background: Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting up to 10% of women of childbearing age. Traditionally, androgen elevation has been considered the main pathological cause for PCOS. However, it is increasingly recognized that bone morphogenetic proteins (BMPs), members of the transforming growth factor β (TGF-β) family, play important roles in follicle recruitment, follicle selection, and follicle-stimulating hormone (FSH) responsiveness. Methods: Twenty-eight PCOS patients and fourteen tubular infertility patients were recruited from patients seeking reproductive assistance at The Center of Reproductive Medicine in Taiyuan, China. Each patient went through an in vitro fertilization and embryo transplantation (IVF-ET) procedure. The mRNA and protein levels of hormones, hormone receptors, and BMPs were evaluated using real-time PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Results: Hormone levels were comparable in PCOS and control patients. In contrast, significant differences were observed in BMP levels in these two groups. BMP-5, -6, -7, and -8A levels were all markedly lower in follicular fluid in PCOS patients (p<0.05), with BMP-7 being the most significantly down regulated biomarker (p=0.0004). The levels of all BMPs were positively correlated with follicle-stimulating hormone receptor (FSHR). Conclusions: Expression levels of multiple BMPs were significantly down-regulated in follicular fluid from PCOS patients. Their low abundance as well as their correlation with FSHR confirmed BMPs as key regulators of PCOS pathogenesis.