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: 17ß-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.

Nerve fiber density in deep nodular endometriotic lesions induced in a baboon experimental model.

OBJECTIVE: To study the occurrence of nerve fibers in deep nodular endometriotic lesions after nodules were induced in baboons and nerve fiber densities measured 6 months after the grafting procedure. DESIGN: Experimental animal study. SETTING: Academic gynecology research unit. ANIMALS: Ten baboons (Papio anubis). INTERVENTION(S): Recovery of induced endometriotic nodules and eutopic endometrium. MAIN OUTCOME MEASURE(S): Protein gene product (PGP) 9.5 and nerve growth factor (NGF) immunohistochemistries were performed to evaluate nerve fiber density and NGF expression in induced endometriotic lesions and eutopic endometrium. RESULT(S): Eutopic (basalis) endometrium, myometrium, and invasive and noninvasive nodular lesions were analyzed separately. The highest nerve fiber densities were observed in normal myometrium and in the basal layer of eutopic endometrium. No significant differences were observed between the two lesion types. However, the NGF staining intensity score was found to be higher in glands of deep invasive lesions than in glands of eutopic baboon endometrium. CONCLUSION(S): This is the first study to show the presence of nerve fibers in eutopic baboon endometrium and induced deep endometriotic nodules. Long-term studies are now warranted to determine if nerves still grow in invasive and noninvasive lesions >6 months after grafting, and to evaluate the role of the lesion environment.

Induction of endometriotic nodules in an experimental baboon model mimicking human deep nodular lesions.

OBJECTIVE: To establish an experimental model for the study of deep nodular endometriosis. DESIGN: Induction of nodular endometriosis in baboons by grafting different uterine specimens to the peritoneal cavity. SETTING: Research and university facilities. ANIMAL(S): Ten baboons, to develop a model of induced deep nodular endometriosis. INTERVENTION(S): Biopsies of endometrium, and endometrium plus the junctional zone (JZ), full uterine thickness, and myometrium grafted to the peritoneum. MAIN OUTCOME MEASURE(S): Macroscopic descriptions recorded for observed induced lesions; staining with hematoxylin and eosin for histological evaluation and specific antibodies (CK22, CD10) for immunohistochemical studies; and analysis of surface area and volume of lesions, glandular density, and invasion of surrounding organs. RESULT(S): The incidence of induced nodular endometriosis was 100%, but the extent depended on the tissue grafted. Lesions induced after grafting specimens containing the JZ were statistically significantly larger than those not containing the JZ. Surrounding organ invasion was reported in more than 40% of lesions after grafting specimens containing the JZ. CONCLUSION(S): The first experimental model of nodular endometriosis allows investigation of deeper nodular lesions as well as invasion phenomena associated with nodular lesions.

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.

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.

Insights into iron and nuclear factor-kappa B (NF-kappaB) involvement in chronic inflammatory processes in peritoneal endometriosis.

Endometriosis is a chronic pelvic inflammatory process. Local inflammation is known to play a role in pain and infertility associated with the disease, and may be extensively involved in molecular and cellular processes leading to endometriosis development. In this review, we focus on two inflammatory mediators clearly implicated in the pathogenesis of endometriosis, iron and NF-kappaB, and their potential association. Iron is essential for all living organisms, but excess iron results in toxicity and is linked to pathological disorders. In endometriosis patients, iron overload has been demonstrated in the different compartments of the peritoneal cavity (peritoneal fluid, endometriotic lesions, peritoneum and macrophages). This iron overload affects numerous mechanisms involved in endometriosis development. Moreover, iron can generate free radical species able to react with a wide range of cellular constituents, inducing cellular damage. Overproduction of reactive oxygen species also impairs cellular function by altering gene expression via regulation of redox-sensitive transcription factors such as NF-kappaB, which is clearly implicated in endometriosis. Indeed, NF-kappaB is activated in endometriotic lesions and peritoneal macrophages of endometriosis patients, which stimulates synthesis of proinflammatory cytokines, generating a positive feedback loop in the NF-kappaB pathway. NF-kappaB-mediated gene transcription promotes a variety of processes, including endometriotic lesion establishment, maintenance and development. In conclusion, iron and NF-kappaB appear to be linked and both are clearly involved in endometriosis development, making these pathways an attractive target for future treatment and prevention of this disease.

Are aromatase inhibitors effective in endometriosis treatment?

INTRODUCTION: Current therapies for endometriosis cannot completely cure the disease, and patients present with high recurrence rates. Novel medical approaches are, therefore, needed. AREAS COVERED: In endometriosis, aromatase was long thought to be involved in the in situ formation of estrogens, leading to a positive feedback loop favoring estrogens, themselves inducing prostaglandin production and inflammation. This hypothesis led to aromatase inhibitors (AIs) being proposed as the new medical therapy for endometriosis, as reported in all the studies reviewed here. Recent findings nevertheless indicate that aromatase may be less implicated in endometriosis than previously postulated. More than 10 years after the first successful treatment of a rare and severe case of postmenopausal endometriosis with an AI, there are only three small randomized controlled trials in the literature. EXPERT OPINION: Until recently, AIs were thought to be an alternative to current medical therapies for endometriosis. However, recent findings question their real utility in clinical practice in the context of this disease. Because there is no strong evidence of their efficacy or benefit compared to other molecules in existing clinical trials, AIs need to be investigated further in well-designed studies to confirm/disprove their hypothetical impact on endometriotic lesions.

Involvement of the nuclear factor-κB pathway in the pathogenesis of endometriosis.

OBJECTIVE: To evaluate the role of nuclear factor-κB (NF-κB) in the pathogenesis of endometriosis. DESIGN: A literature search was conducted in PubMed to identify all relevant citations. RESULT(S): Our findings highlight the important role of NF-κB in the pathophysiology of endometriosis. In vitro and in vivo studies show that NF-κB-mediated gene transcription promotes inflammation, invasion, angiogenesis, and cell proliferation and inhibits apoptosis of endometriotic cells. Constitutive activation of NF-κB has been demonstrated in endometriotic lesions and peritoneal macrophages of endometriosis patients. Agents blocking NF-κB are effective inhibitors of endometriosis development and some drugs with known NF-κB inhibitory properties have proved efficient at reducing endometriosis-associated symptoms in women. Iron overload activates NF-κB in macrophages. NF-κB activation in macrophages and ectopic endometrial cells stimulates synthesis of proinflammatory cytokines, generating a positive feedback loop in the NF-κB pathway and promoting endometriotic lesion establishment, maintenance and development. CONCLUSION(S): NF-κB transcriptional activity modulates key cell processes contributing to the initiation and progression of endometriosis. Because endometriosis is a multifactorial disease, inhibiting NF-κB appears to be a promising strategy for future therapies targeting different cell functions involved in endometriosis development, such as cell adhesion, invasion, angiogenesis, inflammation, proliferation, and apoptosis. Upcoming research will elucidate these hypotheses.

Evaluation of estrogen treatment in an immunodeficient mouse endometriosis model.

BACKGROUND/AIMS: Endometriosis is known to be an estrogen-dependent disease. However, only a few studies have analyzed the effect of estrogen treatment in mice xenotransplanted with human endometrium. The objective of this study was to adapt a previously developed heterologous murine model to the study of estrogens and test the impact of estrone treatment on endometriosis development. METHODS: Human proliferative endometrium was xenotransplanted into the peritoneal cavity of castrated immunodeficient mice. These mice were treated with estrogens by means of subcutaneous estrone-releasing pellets. The effect of estrone on estradiol level, uterine histology and endometriosis development was evaluated after 21 days. RESULTS: Bioactivity of estrone pellets and their metabolization into estradiol were demonstrated. However, there was no impact on endometriosis development (no difference in lesion number, weight, size or fluorescence). This lack of response was not due to absence of estrogen receptor expression, since strong expression was found in all lesions harvested. Surprisingly, castrated nontreated mice presented with lesions showing high proliferative activity, similar to lesions found in treated mice (around 30%). CONCLUSION: The high proliferation observed in lesions recovered from ovariectomized nontreated mice questions the utility of using estrogens in heterologous murine models.

Review: luminescence as a tool to assess pelvic endometriosis development in murine models.

Classic murine endometriosis models may be insufficient to evaluate the effect of therapeutic agents on endometriosis development, because the process of identification and measurement of induced lesions is often impeded, as implants are small and embedded in murine tissue. In this context, as summarized in the current review, luminescence techniques have proved useful for identifying and visualizing or quantifying endometriotic transplants. They are also a valuable tool for endometrial cell tracking in live animals, yielding further information by adding spatial and temporal dimensions to biological processes in vivo. Such approaches involve transplanting luminescently labeled murine or human endometrium into animals. Two main strategies are applied to label endometrium before injection: use of genetically modified tissue or tissue labeled with a fluorescent dye. Each model has its advantages and disadvantages, the choice of model depends on the study objectives/design (long- or short-term studies, homologous or heterologous model).

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.