Serum concentration of bone morphogenetic proteins (BMPs) is not linked to serum anti-mullerian hormone (AMH) level

Serum concentration of anti-mullerian hormone (AMH) is used as a biomarker in practical clinics. As bone morphogenetic protein (BMP) cytokines induce AMH expression in human granulosa cells (GC) in vitro, serum concentrations of BMP cytokines and AMH were evaluated whether there would be a relationship between BMP cytokines and AMH. Serum concentrations of BMP-2, -6 -7, AMH and FSH were measured in 25 infertility patients using EIA or ELISA kits. Among 25 infertile patients, serum BMP-2, -6, and -7 were detected only in 10, 3, 7 patients respectively, while AMH was detected in 24 out of 25 patients. There was no relation between BMP cytokines and AMH concentration in serum. The detection rate of these BMPs in serum was much lower than that of AMH. Serum concentration of BMP-2, -6, -7 could not estimate serum AMH level. Introduction In infertility treatments, the precise assessment of ovarian reserve is necessary to plan a treatment strategy for each patient. Among all available markers of ovarian reserve, much interest has been given to anti-mullerian hormone (AMH) as a reliable, accurate and reproducible predictor [1,2]. AMH, which belongs to the transforming growth factor (TGF)β superfamily, is a product of the granulosa cells (GC) in pre-antral and small antral follicles [3]. As serum concentration of AMH which is derived from GC, is considered an excellent biomarker in practical clinics [1,2], it is important to elucidate the mechanism by which AMH is regulated in GC. Previously, we found that bone morphogenetic protein (BMP)-2, 6, 7 and 15 increased the expression of AMH in human GC [4,5]. BMP cytokines which are member of TGF-β superfamily, are known to regulate ovarian physiology; including gonadogenesis [6,7], folliculogenesis, ovulation and luteinization in various species [8]. In the human ovary, it has been reported that GC express BMP-2 and -6, theca cells express BMP-7 and oocytes express BMP-6, -15 respectively [4,9-13]. Given that BMP cytokines regulate ovarian function, including AMH expression, serum concentrations of BMP cytokines could be a useful marker for the ovarian function. In the present study, we validated the hypothesis whether the measurement of the BMP cytokines in serum could be a predictor for ovarian reserve. Materials and methods Reagents and materials The concentrations of serum BMPs were measured using ELISA kits for BMP-6 and -7 from RayBiotech (Norcross, GA), and for BMP2 from R&D Systems. Serum AMH concentrations were measured using the EIA kit from Beckman Coulter (Tokyo, Japan). Written informed consent was obtained from all of the study participants. Ethical approval was given by Tokyo University Ethics Committee. Serum sample A total of 25 infertile women were recruited for the study. The mean age of subjects was 35.0 years (20-43 years). All of them had regular menstrual cycles of around 28 days duration. On day 3-5 of a spontaneous menstrual cycle, blood samples were obtained by venipuncture. The FSH concentration were measured using the immulite semiautomated assay system. Plasma for assay of AMH, BMP-2, 6, and 7 was separated immediately from blood and frozen in aliquots at -80°C until thawed and assayed. A concentration of sensitivity, intra and inter-assay coefficients of variation respectively were as follow; BMP-2: 10 pg/ml, <5%, <10%, BMP-6: 80 pg/ml, <10%, <12%, BMP-7; 10 pg/ml, <10%, <12%, AMH: 70 pg/ml, <13%, <15%. Statistical analysis Data were analyzed by Pearson’s correlation coefficient using Statview software (SAS Institute Inc., Cary, NC). A p-value of less than 0.05 was considered statistically significant. Correspondence to: Osamu Yoshino and Yutaka Osuga, Department of Obstetrics and Gynecology, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-8655, Japan, Tel: +81-3-3815-5411 (33407); Fax: +81-3-38162017; E-mail: [email protected], [email protected]