Alterations in the Calcitonin and Calcitonin Modulated Proteins, E-Cadherin and the Enzyme Tissue Transglutaminase II during the Window of Implantation in a Baboon Model of Endometriosis

Abstract

Endometriosis is a gynecological condition associated with infertility. We have previously demonstrated dysregulation of several molecular markers of uterine receptivity in a baboon model of induced endometriosis. Specifically, reduced levels of endometrial progesterone receptor (PR) and progesterone (P)-regulated genes, HOXA10 and FKBP52 were observed during the window of uterine receptivity in baboons with endometriosis, suggesting that this disease results in the development of an endometrial P resistance. In this study calcitonin (CALC) and CALC-modulated proteins, E-cadherin (E-Cad) and tissue Transglutaminase (tTgase-2) were evaluated in the eutopic endometrium of endometriotic animals throughout disease progression. Endometriosis was induced in normal cycling baboons by intraperitoneal inoculation of menstrual endometrium. Eutopic and ectopic endometrium was harvested consecutively from each animal at 1, 6 and 15 months of disease, during the window of receptivity. Control eutopic endometrium was similarly harvested from disease free baboons. Immunohistochemistry for CALC, E-cad and tTgase-2, was performed on formalin fixed tissues embedded in paraffin following antigen retrieval. CALC immunostaining was localized in the glandular and luminal epithelium as well as in the uterine stromal cells in disease free eutopic endometrium. However, in the eutopic endometrium from endometriotic baboons there was a reduction of CALC in the luminal and glandular epithelium as well as a reduction in the stromal cells. In the ectopic endometrium there was no immunostaining for the CALC protein. E-cad protein was immunolocalized primarily to the glandular epithelium of both control and endometriotic eutopic endometria. However, E-cad immunostaining was markedly increased in endometria of baboons with disease. The immunostaining was weak for E-Cad in the ectopic endometrial lesions regardless of color or location in the peritoneum. Strong immunostaining for tTgase-2 was observed in the stroma in disease free controls. Endometria from animals with endometriosis demonstrated a progressive loss of tTgase-2 immunostaining in the stroma throughout the time course of disease. There was strong immunostaining in the stroma of the ectopic endometrial collected throughout disease progression. The maintained levels of E-cad and reduced levels of tTgase-2 correlate with the reduction of CALC in eutopic endometria of baboons with endometriosis. These data suggest that the reduced fecundity associated with endometriosis is mediated, in part, by a progesterone resistance that affects not only genes directly regulated by progesterone, but those that are down-stream targets of progesterone regulated genes.