Leiomyoma simultaneously impair endometrial BMP-2-mediated decidualization and anticoagulant expression through secretion of TGF-β3.

CONTEXT

Uterine leiomyomas occur in 30-70% of reproductive-age women. Leiomyoma reduce implantation, increase miscarriage risk, and increase menstrual bleeding. We hypothesized that endometrial defects induced by leiomyoma result in menorrhagia and reproductive dysfunction.

OBJECTIVES

We evaluated the effect of leiomyoma on endometrial gene expression essential for implantation and hemostasis both in vivo and in primary endometrial stromal cells (ESC).

DESIGN AND SETTING

We conducted a case control and in vitro study at a university medical center.

PATIENTS

The study included 24 subjects with or without leiomyoma. INTERVENTION/MAIN OUTCOME MEASURED: Endometrium, myometrium, leiomyoma, and ESC were obtained. Immunohistochemistry was used to evaluate TGF-β3, bone morphogenetic protein (BMP) receptors (BMPRs), plasminogen activator inhibitor 1 (PAI-1), and thrombomodulin in vivo. BMP-2 secretion was assessed by ELISA. ESC were treated with recombinant human (rh) BMP-2 or rhTGF-β3. Expression of HOXA10, LIF, BMPRs, antithrombin III (ATIII), thrombomodulin, and PAI-1 was assessed by quantitative RT-PCR.

RESULTS

ESC from controls secreted more BMP-2 than those from women with leiomyoma. HOXA10 and LIF expression increased after rhBMP-2 treatment of normal but not leiomyoma-associated ESC. In vivo leiomyoma-associated endometrium expressed lower levels of BMPR 1A, 1B, and 2 than controls. Leiomyoma expressed high levels of TGF-β3; TGF-β3 treatment of ESC reduced expression of BMPRs. Similarly, leiomyoma-associated endometrium expressed less PAI-1 and thrombomodulin in vivo. In ESC, TGF-β3 reduced expression of PAI-1, ATIII, and thrombomodulin.

CONCLUSIONS

Leiomyoma-secreted TGF-β3 induces BMP-2 resistance in endometrium by down-regulation of BMPR-2, likely causing defective endometrial decidualization. TGF-β3 also reduces expression of PAI-1, ATIII, and thrombomodulin in endometrium, likely contributing to menorrhagia. A single molecular signal targeting endometrium may mediate both leiomyoma-induced infertility and bleeding.