Role of FoxP3+Treg cells in decreased occurrence of endometriosis in women with benign ovarian cyst

Background:Wepreviously demonstrated a remarkably higher association of pelvic endometriosis in women with ovarian endometrioma. However, information regarding occurrence of pelvic endometriosis in women with demoid cyst is unknown even thesewomenexperience similar retrogrademenstruation like womenwithovarianendometriosis.During theprocessof endometrial cell attachment, an event of immunedefect or tolerance occurs that finally decide the survival or clearance of autologous cells in pelvic environment. Here, we retrospectively evaluated recorded files of laparoscopy from 1982 to 2008 at our university and examined the incidence of pelvic endometriosis in women with benign ovarian cysts. Material and methods: We performed a retrospective study conducted in 2988 cases that had undergone laparoscopic surgery between September 1982 and April 2008 for the indication of ectopic pregnancy, tubal infertility and other benign gynecologic diseases. We analyzed occurrence of pelvic endometriosis in women with ovarian endometrioma and dermoid cyst during 25 years observation period.With informed consent, cystwall from20 womenwithdermoidcysts and20womenwithovarianendometrioma and corresponding eutopic endometria and peritoneal tissues were prospectively collected during laparoscopy. Tissue expression of FOXP3+ Treg cells was examined by immunohistochemistry and peritoneal fluid (PF) levels of TGF and IL-6 were measured by ELISA. Results: Among 2988 laparoscopy cases, 350 cases (11.7%)were found to have ovarian endometrioma, 414 (13.8%) cases had dermoid cyst and 398 (13.3%) cases were treated for fertility screening or uterine myoma with bilateral pathology free ovary. A predominance of both ovarian endometrioma and dermoid cysts was found inwomen in their 20th and30thyears of age.Womenwithdermoid cysts had a significantly decreased occurrence of pelvic endometriosis (74 cases, 18.6%) when compared with that of women with ovarian endometrioma (267 cases, 76.3%) and with women with bilateral normal ovary (188 cases, 47.2%). A significantly higher expressionof FOXP3, a transcriptional factorofTregcells,was found in cyst wall and peritoneum of women with dermoid cysts having peritoneal lesions comparing to similar tissues derived from dermoid cysts without any peritoneal lesions. A relationship between FOXP3 expression and TGF /interleukin-6 levels in peritoneal fluid (PF) will be discussed. Conclusions: Higher FOXP3+ Treg cells in the peritoneum may be associated with decreased occurrence of peritoneal lesions in women with benign ovarian cyst. A possible immunosurveillance secondary to different pelvic environmentmight be involved in this protective effect against endometriosis.