Localization of laminin, fibronectin, E-cadherin, and integrins in endometrium and endometriosis

OBJECTIVE: To compare the localization of adhesion proteins (laminin and fibronectin) and their receptors of the integrin family in endometriosis and endometrium. DESIGN: An immunohistochemical study. SETTING: University Hospital, Department of Gynecology and Department of Cell Biology. PATIENT(S): Eighteen endometriosis patients undergoing laparoscopy for pain or infertility and nine control patients undergoing laparoscopy for sterilization or hysterectomy. MAIN OUTCOME MEASURE(S): The expression of adhesion glycoproteins (laminin and fibronectin), their receptors alpha 1 beta 1, alpha 2 beta 1, alpha 3 beta 1, alpha 5 beta 1, and alpha 6 beta 1, and E-cadherin was determined by immunohistochemistry on frozen sections. RESULT(S): The distribution of both adhesive glycoproteins, laminin and fibronectin, and their receptors was identical in endometriosis and endometrium. Fibronectin receptors (alpha 4 beta 1, alpha 5 beta 1) displayed distinct expression patterns in endometrium and endometriosis. No endometrial glands showed positive staining for the alpha 5 chain, whereas this integrin subunit was detected in almost all endometriotic lesions. The integrin alpha 4 chain was present in all endometriotic glands but was absent from endometrial glands in the proliferative phase of the cycle. CONCLUSION(S): No difference in cell adhesion molecule localization nor receptors was observed between endometriotic and endometrial samples, except for fibronectin receptors. Their expression persisted around endometriotic glands but not in endometrium. These results suggest that fibronectin receptors could play a role in the persistence of endometriotic lesions, despite menstruation in corresponding eutopic endometrium.