Expression of Smad 3, Smad 3p and Smad 4 in Eutopic Endometrium of Women with and Without Endometriosis.

Endometriosis is a gynecological disease characterized by endometrial tissue outside the uterine cavity and it is associated with pelvic pain and infertility. Members of the TGF-beta family initiate their actions through activation of type I and II receptors and subsequent activation of intracellular Smads proteins (2 and 3). These proteins interact with a common Smad 4 and this complex is translocated to the nucleus where it combines with DNA-binding proteins at the promoter regions of target genes. Currently, there are no reports of Smads protein expression in endometriosis. The present study evaluated the immunolocalization of Smad 3, Smad 3p and Smad 4 in eutopic endometrium of women with (n=9) and without (n=16) endometriosis. All endometrial tissues were obtained during the proliferative phase of women undergoing hysteroscopy for in vitro fertilization. Our results showed protein expression in all the endometrial compartments analyzed: glandular epithelium and stroma. Smad 3, Smad 3p and Smad 4 immunostaining were both citoplasmatic and nuclear. No statistical differences were found in the Smad 3, Smad 3p and Smad 4 immunostaining intensities from women with and without endometriosis. However, Smad 4 (a protein involved in the activation of gene transcription) showed a nucleus staining of 44.44% in the endometriotic group compared to 26.47% in the control group. Therefore, these results suggest that Smads proteins might be involved in the endometriosis pathogenesis. This research was supported by Brazilian National Institute of Hormones and Women′s Health and CNPq.