Time course of pelvic endometriotic lesion revascularization in a nude mouse model.

OBJECTIVE: To assess the timing of endometrial lesion revascularization in a murine model. DESIGN: Prospective experimental study. SETTING: An academic research environment. ANIMAL(S): Twenty-six nude mice. INTERVENTION(S): Endometriosis was induced in mice by intraperitoneal deposition of human menstrual endometrium. Endometrial implants were recovered on days 1, 3, 5, 8, 10, 15, and 21 after implantation. MAIN OUTCOME MEASURE(S): Sections from the endometrial implants were immunostained with species-specific antiplatelet endothelial cell adhesion molecule-1 (PECAM-1) antibodies and vessels of murine and human origin were counted. RESULT(S): Endothelial cells of human origin in the implant progressively disappeared between day 3 and day 10. Seventy-eight percent of the vessel sections were positive for human PECAM-1 on day 5, 40.1% on day 8, and only 14.1% on day 10. However, there was a marked increase in murine PECAM-1-expressing vessels in endometrial stroma between day 5 (1.4%) and day 8 (68.0%), 10 (69.5%), and 15 (87.2%). CONCLUSION(S): Our study demonstrates that PECAM-1 is a reliable endothelial cell marker to evaluate the role of angiogenesis in the nude mouse model. It also indicates that revascularization of human endometrial implants occurs between 5 and 8 days after implantation and involves the disappearance of native graft vessels, coinciding with the invasion of the interface and then the stroma by murine vessels.

Expression of platelet endothelial cell adhesion molecule-1 in red and black endometriotic lesions.

This immunohistochemical study shows that platelet endothelial cell adhesion molecule-1 (PECAM-1), known to play a role in neoangiogenesis and vascular development, is strongly and homogeneously expressed in endothelial cells lining blood vessels from red and black pelvic endometriotic lesions. The distribution of PECAM-1 within the stroma of the lesions was similar to that found in the corresponding eutopic endometrium, regardless of the phase of the cycle.

Characterization of iron deposition in endometriotic lesions induced in the nude mouse model.

BACKGROUND: Pelvic endometriotic lesions are often laden with hemosiderin. In order to investigate the potential source of such iron deposits, we examined whether the seric and erythrocyte fractions of menstrual effluent might influence the occurrence of iron deposition within lesions in a murine model of endometriosis. METHODS: Endometriosis was induced in 57 nude mice by intraperitoneal injection of unfractionated human menstrual effluent, endometrial fragments plus serum, endometrial fragments plus erythrocytes or endometrial cell fraction alone. The number of implants, histologic aspect, proliferative activity and iron deposition in lesions was assessed. RESULTS: On day 5, lesions were evidenced in all 10 mice receiving menstrual effluent, in 9/13 of those injected with the cellular fraction, in 10/13 with the cellular fraction plus serum and in 10/12 with the cellular fraction plus erythrocytes. Iron conglomerates were observed at the interface between the lesion and peritoneum when menstrual effluent (47 deposits/mm(2)) and the cellular fraction with erythrocytes (20 deposits/mm(2)) were injected, but were scarce when the cellular fraction was injected without erythrocytes, either alone (4 deposits/mm(2)) or with serum (2 deposits/mm(2)) (P < 0.05). CONCLUSIONS: Iron conglomerates, typically found in the stroma of endometriotic lesions, were induced by erythrocytes present in menstrual effluent. This may be one of the factors triggering oxidative damage and chronic inflammation.

Typical and subtle atypical presentations of endometriosis.

The diagnosis of peritoneal endometriosis at the time of laparoscopy is often made by the observation of typically puckered black or bluish lesions. There are also numerous subtle appearances of peritoneal endometriosis. The lesions are frequently non-pigmented. Red flame-like lesions, glandular excrescences, and subovarian adhesions must be considered as the most active lesions. Sometimes, however, subtle endometriotic lesions can be the only lesions seen at laparoscopy.

Iron overload in the peritoneal cavity of women with pelvic endometriosis.

OBJECTIVE: To examine the possible involvement of iron in the physiopathology of endometriosis. DESIGN: Prospective study. SETTING: Department of gynecology in a university hospital. PATIENT(S): Seventy patients undergoing laparoscopy. INTERVENTION(S): Collection of peritoneal fluid (n = 57), blood samples, and biopsy samples from endometrium (n = 62) and from endometriotic (n = 33) and normal-appearing peritoneum (n = 53). MAIN OUTCOME MEASURE(S): Measurement of iron and ferritin in serum and peritoneal fluid and staining of iron deposits with Prussian blue in tissues. RESULT(S): Iron and ferritin concentrations were significantly higher in the peritoneal fluid of patients with endometriosis compared with controls during the secretory phase. Higher rates of ferritin and hemosiderin deposits were observed in the peritoneum adjacent to red (100%), black (57%), and white (62%) lesions compared with normal-appearing peritoneum (25%). Deposits were more frequent during the secretory phase than the proliferative phase in healthy peritoneum from controls, whereas they were found throughout the cycle in the vicinity of lesions in patients with endometriosis. Similar rates of iron deposition were observed in the stroma of black and white lesions and in eutopic endometrium from patients with endometriosis. CONCLUSION(S): Iron overload was observed in the cellular and peritoneal fluid compartments of the peritoneal cavity of women with endometriosis. Iron deposits seem to be related to the presence of lesions, suggesting that iron may be involved in the pathogenesis of endometriosis.

Oxidative stress and peritoneal endometriosis.

OBJECTIVE: To review the literature associating pelvic endometriosis with oxidative stress and to discuss the potential causes and consequences of a pro-oxidant environment in the peritoneal cavity. DESIGN: Literature survey. RESULT(S): Several studies suggest that oxidative stress is a component of the inflammatory reaction associated with endometriosis. Evidence includes the prevention of endometriosis induction in rabbits by the addition of antioxidants, an increase in reactive oxygen species release by macrophages, increased peritoneal levels of oxidized low-density lipoproteins and their by-products, altered expression of endometrial pro-oxidant and antioxidant enzymes, and consumption of peritoneal fluid vitamin E. Retrograde menstruation is likely to carry highly pro-oxidant factors, such as heme and iron, into the peritoneal cavity, as well as apoptotic endometrial cells, which are well-known inducers of oxidative stress. Reactive oxygen species may be involved in endometriosis-associated infertility and may play a role in the regulation of the expression of genes encoding immunoregulators, cytokines and cell adhesion molecules implicated in the pathogenesis of endometriosis. CONCLUSION(S): Better understanding of the mechanisms of reactive oxygen species production and detoxification and further investigation of their effect on the peritoneal environment are essential to obtain new insight into this disease and eventually develop new diagnostic and therapeutic strategies.

Potential involvement of hemoglobin and heme in the pathogenesis of peritoneal endometriosis.

OBJECTIVE: To test whether hemoglobin may accumulate in the peritoneal cavity in case of endometriosis and to assess whether heme oxygenases (HO), detoxifying heme, are expressed in ectopic endometrium and peritoneal cells. DESIGN: Prospective study involving patients with and without endometriosis. SETTING: Department of gynecology in a university hospital. PATIENT(S): Seventy-six patients undergoing laparoscopy for tubal sterilization or infertility and/or pelvic pain. INTERVENTION(S): Collection of peritoneal fluid (PF), blood samples, and biopsies from endometrium and peritoneum. MAIN OUTCOME MEASURE(S): Measurement of free hemoglobin and its byproduct, total and direct bilirubin, in serum and PF and analysis of HO-1 and HO-2 expression in biopsies by reverse transcription polymerase chain reaction and semiquantitative immunohistochemistry. RESULT(S): Higher levels of hemoglobin were found in the PF of patients with endometriosis. There was no concomitant increase in bilirubin concentrations in the PF, and HO-1 was poorly expressed in peritoneal mesothelium and macrophages. Heme oxygenase-1 and HO-2 were strongly expressed in ectopic endometrium, especially in red lesions. CONCLUSION(S): Our results suggest that heme may be involved in the pathogenesis and/or development of endometriosis and that the HO system, although expressed, might be insufficient to detoxify heme in women with endometriosis.