Plasminogen activators in ectopic and uterine endometrium

OBJECTIVE: To investigate the expression of the plasminogen activator (PA)-plasmin system components in ectopic endometrium and in uterine endometrium from women with and without endometriosis. DESIGN: Plasminogen, PAs (urokinase and tissue plasminogen activator), and PA inhibitors (1 and 2) were detected by immunohistochemistry using a alkaline phosphatase staining method. RESULTS: No differences in staining were found between uterine endometrium of women with endometriosis and women without endometriosis with any of the antibodies used. However, we did find differences between uterine and ectopic endometrium. Although the expression of the components of the PA-plasmin system reflected the cyclic changes in the hormonal levels in uterine endometrium, ectopic endometrium maintained a very high level of plasminogen and urokinase in every sample. We were unable to detect the presence of PA inhibitors in either uterine or ectopic endometrium. CONCLUSIONS: There is no evidence that uterine endometrium from women with endometriosis is originally more able to implant than that of women without the disease because of an increase in their PA expression. The high levels of urokinase and plasminogen in ectopic endometrium may reflect a more invasive nature of the endometriotic implants in the peritoneal cavity.