Sylvie Defrère

Endometriomas as a possible cause of reduced ovarian reserve in women with endometriosis.

OBJECTIVE To evaluate the adverse effects of endometriomas on ovarian reserve. DESIGN Analysis of prospectively collected biopsy samples. SETTING Gynecology research unit in a university hospital. PATIENT(S) Women younger than age 35 years with endometriomas. INTERVENTION(S) Biopsy of normal cortex from ovaries affected by endometriomas (≤4 cm) and contralateral ovaries without cysts. MAIN OUTCOME MEASURE(S) Presence of cortex-specific stroma, observation of superficial endometriosis, follicular density, and presence of fibrosis. RESULT(S) Twenty samples of cortical tissue from ovaries with endometriomas and 11 from contralateral ovaries without cysts were analyzed. Follicular density was significantly lower in cortex from ovaries with endometriomas than in cortex from contralateral ovaries without cysts (mean ± SD = 6.3 ± 4.1/mm(3) vs 25.1 ± 15.0/mm(3)). Eleven (55%) cortical samples from ovaries with endometriomas showed fibrosis and concomitant loss of cortex-specific stroma, not observed in contralateral normal ovaries. Multivariate analysis revealed that the presence of endometrioma and fibrosis were significantly and independently associated with follicular density. CONCLUSION(S) Endometriotic cyst formation and associated structural tissue alterations in apparently normal ovarian cortex may be a cause of reduced ovarian reserve. Early diagnosis and intervention may be beneficial in women with endometriomas to protect their ovarian function.

Potential involvement of iron in the pathogenesis of peritoneal endometriosis

The aim of this study is to review the current literature associating endometriosis with iron and to discuss the potential causes and consequences of iron overload in the pelvic cavity. Indeed, iron is essential for all living organisms. However, excess iron can result in toxicity and is associated with pathological disorders. In endometriosis patients, iron overload has been demonstrated in the different components of the peritoneal cavity (peritoneal fluid, endometriotic lesions, peritoneum and macrophages). Animal models allow us to gather essential information on the origin, metabolism and effect of iron overload in endometriosis, which may originate from erythrocytes carried into the pelvic cavity mainly by retrograde menstruation. Peritoneal macrophages play an important role in the degradation of these erythrocytes and in subsequent peritoneal iron metabolism. Iron overload could affect a wide range of mechanisms involved in endometriosis development, such as oxidative stress or lesion proliferation. In conclusion, excess iron accumulation can result in toxicity and may be one of the factors contributing to the development of endometriosis. Treatment with an iron chelator could thus be beneficial in endometriosis patients to prevent iron overload in the pelvic cavity, thereby diminishing its deleterious effect.

Absence of aromatase protein and mRNA expression in endometriosis.

BACKGROUND Aromatase has been reported to be involved in estrogen biosynthesis and expressed in eutopic and ectopic endometrium of endometriosis patients. The objective of the present study was to investigate its expression and localization in three distinct types of endometriosis. METHODS Human peritoneal, ovarian and rectovaginal endometriotic lesions and matched eutopic endometrium were collected from patients during laparoscopy. Aromatase protein localization (immunohistochemistry, n = 63) and mRNA expression [quantitative polymerase chain reaction (Q-PCR), n = 64] were assessed. RESULTS No aromatase protein was detected by immunohistochemistry in either the glandular or stromal compartment of endometriotic lesions or eutopic endometrium, while it was strong in placental syncytiotrophoblasts, granulosa and internal theca cells from pre-ovulatory follicles, and luteal cells from corpus luteum. By Q-PCR, low but discernible levels of aromatase expression were found in endometriomas, probably due to follicular expression. Transcripts for aromatase were barely detectable in only a few peritoneal and rectovaginal endometriotic lesions, and a few eutopic endometrium samples, probably due to contaminating surrounding tissues (adipose tissue, intact peritoneum). CONCLUSIONS Unlike previous studies, we observed no aromatase protein in any of the endometriosis types, and barely detectable aromatase mRNA expression, suggesting that locally produced aromatase (within endometriotic lesions) may be less implicated in endometriosis development than previously postulated. Potential factors responsible for these discrepancies are discussed.

Agents Blocking the Nuclear Factor-κB Pathway Are Effective Inhibitors of Endometriosis in an in vivo Experimental Model

Background: In vitro studies suggest that the transcription factor nuclear factor-kappa B (NF-ĸB) is implicated in the transduction of proinflammatory signals in endometriosis. The aim of this study was to investigate the involvement of NF-ĸB and the processes regulated by NF-ĸB in the initial development of endometriotic lesionsin vivo.Methods: Endometriosis was induced in nude mice by intraperitoneal injection of fluorescent-labeled menstrual endometrium. Two NF-ĸB inhibitors (BAY 11-7085 and SN-50) were injected intraperitoneally on days 0, 2 and 4 after endometriosis induction, and endometriotic lesions were recovered on day 5. Number, mass, fluorimetry and surface (morphometry) of endometriotic lesions were quantified. NF-ĸB activation, intercellular adhesion molecule (ICAM)-1 expression, cell proliferation and apoptosis were evaluated by immunohistochemical analyses and the TUNEL method. Results: Both NF-ĸB inhibitors induced a significant reduction in lesion development compared to control mice. NF-ĸB activation and ICAM-1 expression of endometriotic lesions were significantly reduced in treated mice, and cell proliferation was significantly reduced in BAY 11-7085-treated mice. Both inhibitors produced a significant increase in apoptosis of endometriotic lesions, as assessed by active caspase-3 immunostaining and the TUNEL method. Conclusion: This study demonstrates, for the first time, that the NF-ĸB pathway is implicated in the development of endometriotic lesions in vivo and that NF-ĸB inhibition reduces ICAM-1 expression and cell proliferation, but increases apoptosis of endometriotic lesions, diminishing the initial development of endometriosis in an animal model.

ANTIANGIOGENIC AND VASCULAR-DISRUPTING AGENTS IN ENDOMETRIOSIS: PITFALLS AND PROMISES.

It is widely known that angiogenesis plays a key role in endometriotic lesion formation and development. Antiangiogenic treatments aimed at inhibiting new vessel formation have proven efficient in experimental models. However, as antiangiogenic strategies do not target pre-existing pericyte-protected vessels, they require chronic administration and are likely to be beneficial for early-stage disease only or to prevent recurrence after surgery. Moreover, they may have detrimental effects on reproductive function. Vascular-disrupting agents (VDAs) have emerged as a promising new tool for the treatment of tumors. VDAs target established blood vessels, resulting in tumor ischemia and necrosis. These agents may therefore be more efficient against advanced disease. Two major types of VDAs are being developed for cancer: ligand-directed VDAs using antibodies, peptides and growth factors to deliver toxic effectors to tumor endothelium; and small-molecule VDAs exploiting physiological differences between tumor and normal endothelium to induce acute vascular shutdown. The ongoing evolution in genomics and proteomics is revolutionizing the discovery of novel endothelial markers. Several studies suggest that the vasculature of endometriotic lesions may have particular pathophysiological properties, which could be exploited for the development of selective VDAs. The aim of this review is to explore the merits and limitations of vascular therapy for the treatment of endometriosis.

Peritoneal endometriosis is an inflammatory disease.

Peritoneal endometriosis is a chronic inflammatory disease characterized by increased numbers of peritoneal macrophages and their secreted products. Inflammation plays a major role in pain and infertility associated with endometriosis, but is also extensively involved in the molecular processes that lead to peritoneal lesion development. Peritoneal oxidative stress is currently thought to be a major constituent of the endometriosis-associated inflammatory response. Excessive production of reactive oxygen species, secondary to peritoneal influx of pro-oxidants such as heme and iron during retrograde menstruation, may induce cellular damage and increased proinflammatory gene expression through nuclear factor-kappa B activation. In particular, prostaglandin biosynthetic enzyme expression is regulated by this transcriptional factor, and increased peritoneal prostaglandin concentrations have been demonstrated in endometriosis. In the light of available data collected from patient biopsies, as well as in vitro and in vivo studies, the respective involvement and potential molecular interactions of iron, nuclear factor-kappa B and prostaglandins in the pathogenesis of endometriosis are explored and discussed. The key role of peritoneal macrophages is emphasized and potential therapeutic targets are examined.

Iron storage is significantly increased in peritoneal macrophages of endometriosis patients and correlates with iron overload in peritoneal fluid

OBJECTIVE To further investigate peritoneal iron disruption in endometriosis by studying iron storage in peritoneal macrophages of patients with endometriosis compared with controls. DESIGN Cross-sectional study. SETTING Academic gynecology research unit in a university hospital. PATIENT(S) Fifty patients undergoing laparoscopy. INTERVENTION(S) Collection of peritoneal fluid samples (N = 50) from patients with (n = 27) and without (n = 23) endometriosis undergoing laparoscopy. MAIN OUTCOME MEASURE(S) Quantification of peritoneal macrophage ferritin by immunocytochemical staining and immunodensitometry and measurement of peritoneal iron, transferrin, ferritin, and prohepcidin concentrations. RESULT(S) The optical density of peritoneal macrophage ferritin staining was statistically significantly higher in endometriosis patients than in controls. Higher iron concentrations, transferrin saturations, and ferritin concentrations were also detected in case of endometriosis. A statistically significant positive correlation was found between the optical density of macrophage ferritin staining and peritoneal iron concentrations in endometriosis and control patients. CONCLUSION(S) Iron storage is statistically significantly increased in peritoneal macrophages of patients with endometriosis and correlates with iron overload in peritoneal fluid. The potential implications of iron accumulation in peritoneal macrophages in case of endometriosis are discussed.

Inhibition of steroid sulfatase decreases endometriosis in an in vivo murine model

BACKGROUND Steroid sulfatase (STS) is involved in estrogen biosynthesis and expressed in eutopic and ectopic endometrium of disease-free and endometriosis patients. The present study was designed to investigate its role in endometriosis development. METHODS Human endometrial explants were cultured on inserts for 24 h to assess the effectiveness of an STS inhibitor (STS-I), estradiol-3-O-sulfamate (E2MATE), on STS activity in endometrial tissue. Endometriosis was induced in mice, and E2MATE (or vehicle alone) was given orally for 21 days. Plasma estradiol levels were measured, and STS activity was assessed in murine organs (uterus, liver and leukocytes) and in lesions. Lesion number, weight and size (morphometry) were quantified. Lesion STS and progesterone receptor (PR) expression, proliferation and apoptosis rates were determined by immunohistochemistry. RESULTS In vitro, addition of 1 µM E2MATE to the culture medium resulted in decreased STS activity in endometrial explants (P < 0.001). Treatment of mice with E2MATE (1.0 and 0.5 mg/kg) did not modify plasma estradiol levels, but inhibited STS activity in murine uterus (P < 0.05), liver (P < 0.001) and leukocytes (P < 0.001), as well as in induced lesions (P < 0.05). E2MATE reduced lesion weight (P < 0.01) and size (P < 0.05), but had no impact on proliferation or apoptosis rates, nor STS protein expression. Stromal edema was observed in the uterus of animals treated with E2MATE, but not in the stroma of lesions. Increased PR expression was detected in endometriotic lesions (P < 0.001). CONCLUSIONS E2MATE was shown to effectively inhibit STS activity in endometrial tissue in vitro. In vivo, E2MATE decreased endometriosis development without affecting systemic estradiol levels. Use of STS-I could therefore be of potential interest in endometriosis treatment.

Differential expression of steroidogenic enzymes according to endometriosis type.

OBJECTIVE To evaluate, in peritoneal, ovarian, and rectovaginal endometriotic lesions, expression of steroidogenic enzymes involved in the activation and inactivation of estrogens: 17β-hydroxysteroid dehydrogenase type 1 (HSD17B1) and 2 (HSD17B2), estrone sulfotransferase (EST), and steroid sulfatase (STS). SETTING Academic gynecology research unit. DESIGN Retrospective study. PATIENT(S) Disease-free (n = 41) patients and patients with endometriosis (n = 79) were included for quantitative polymerase chain reaction (q-PCR) (15 disease-free, 33 endometriosis) and immunohistochemistry (26 disease-free, 46 endometriosis) studies. INTERVENTION(S) Q-PCR and immunohistochemistry. MAIN OUTCOME MEASURE(S) Evaluation of mRNA and protein expression. RESULT(S) Glandular HSD17B1, HSD17B2, and STS protein expression were demonstrated. HSD17B2 mRNA values were higher in the secretory phase of the menstrual cycle in the endometrium of disease-free women, but not in the eutopic endometrium of patients with endometriosis. HSD17B1 mRNA was equally expressed in the various tissues investigated, and EST mRNA was expressed at low levels in the different lesion types. HSD17B2 mRNA expression was decreased in ovarian and rectovaginal endometriosis compared with eutopic endometrium, while STS mRNA was increased in rectovaginal lesions compared with ovarian lesions. Ratios between pro- and antiestrogenic enzymes (STS/EST and HSD17B1/HSD17B2) were more in favor of estrogens in ovarian and rectovaginal endometriosis. CONCLUSION(S) In endometriosis development, local activation of estrogens appears to be important. STS and HSD17B1 inhibitors may therefore prove useful to treat the disease.

Is the baboon model appropriate for endometriosis studies

OBJECTIVE To determinethe prevalence of spontaneous endometriosis andthe incidence of induced endometriosis after endocervical canal resection in baboons. DESIGN Induction and follow-up of endometriosis in baboons, which is one of the primate species that develop spontaneous endometriosis. Forty-one baboons were checked for the presence of spontaneous endometriosis. We then attempted to induce endometriosis in 30 of them by endocervical canal resection. SETTING Institute of Primate Research, Nairobi, Kenya, and Catholic University of Louvain, Brussels, Belgium. ANIMAL(S) Forty-one baboons were checked for spontaneous endometriosis and 30 of them were used to develop a model of induced endometriosis. INTERVENTION(S) A total of 41 baboons underwent diagnostic laparoscopy for 10 months. In a first step, 30 of this number subsequently underwent endocervical canal resection. In a second step, 20 of the 30 underwent uterine horn resection. MAIN OUTCOME MEASURE(S) Follow-up by laparoscopy. RESULT(S) Two of the 41 baboons were diagnosed with spontaneous endometriosis (4.8%). Twelve months after the surgical procedure to induce endometriosis, 8 of 29 animals presented with endometriotic lesions diagnosed by using laparoscopy and confirmed by histologic examination. The incidence of induced endometriosis in our model was thus 27.6%. In 2 baboons, endometriosis disappeared over time, resulting in a final rate of 20.7% (6/29). CONCLUSION(S) The rate of spontaneous endometriosis is very low (4.8%). Endometriosis can be induced (with a rate of just 27.6%) by endocervical canal resection to stimulate retrograde menstruation.