Peroxisome proliferator-activated receptor-gamma agonist rosiglitazone reduces the size of experimental endometriosis in the rat model

The role of peroxisome proliferator-activated receptors in endometriosis

Endometriosis constitutes the most common cause of chronic pelvic pain in female patients and is associated with infertility. Although there is no known cause for the disease, it is a heritable condition that is determined by numerous genetic, epigenetic, and environmental aspects. Peroxisome proliferator-activated receptors (PPARs) represent nuclear receptor proteins that control gene expression. By using the MEDLINE and LIVIVO databases we conducted a literature review in order to look into the role of PPARs in the endometriosis pathophysiology and succeeded in revealing 36 pertinent publications between 2001 and 2022. In regards to PPAR expression in endometriosis, PPARγ seems to represent the most studied PPAR isoform in endometriosis and to influence various pathways involved in the disease onset and progression. It's interesting to note that diverse treatment agents targeting the PPAR system have been identified as innovative, effective therapeutic alternatives in the context of endometriosis treatment. In conclusion, PPARs appear to contribute an important role in both endometriosis pathophysiology and therapy.

Emerging hallmarks of endometriosis metabolism: A promising target for the treatment of endometriosis

Endometriosis, characterized by ectopic endometrium growth in the extrauterine environment, is one of the most notable diseases of the female reproductive system. Worldwide, endometriosis affects nearly 10 % of women in their reproductive years and causes a significant decline in quality of life. Despite extensive investigations of endometriosis over the past years, the mechanisms of endometriosis pathogenesis remain unclear. In recent years, metabolic factors have increasingly been considered factors in endometriosis. There is compelling evidence regarding the progress of endometriosis in the context of severe metabolic dysfunction. Hence, the curative strategies and ongoing attempts to conquer endometriosis might start with metabolic pathways. This review focuses on metabolic mechanisms and summarizes current research progress. These findings provide valuable information for the non-intrusive diagnosis of the disease and may contribute to the understanding of the pathogenesis of endometriosis.

Antilipidemic ezetimibe induces regression of endometriotic explants in a rat model of endometriosis with its anti-inflammatory and anti-angiogenic effects

To assess the potential therapeutic role of antilipidemic ezetimibe on endometriosis in an experimental rat model. A standard experimental endometriosis model was created with 18 Whistar-Albino rats, and after 1 month, the sizes of the endometriotic explants were measured. The rats were randomized as study and control groups. A total of 1 mg/kg/day ezetimibe and 1 ml/kg/day saline were administered orally to the study and control groups respectively for 28 days. At the end of 28 days, the explants were measured again, excised, and sent for histopathologic assessment for expression of tumor necrosis factor-alpha (TNF-α) and vascular endothelial growth factor (VEGF) and number of mast cells. At the end of the study period, the size of the endometriotic explants decreased significantly in the study group; but not in the control group (from 145.3 ± 120.5 to 89.8 ± 60.1 vs 174.72 ± 88.3 to 87.65 ± 27.1 cm3 respectively); however, the amount of post- and pretreatment differences in explant sizes was similar in the groups. The median TNF-α and VEGF levels were significantly lower in the ezetimibe group when compared to the control group (4 [3-4] vs 2 [1-3], p 0.029; 4 [3-4] vs 2 [2-3], p 0.002; respectively). And numbers of mast cells in all uterine layers were also lower in the ezetimibe group. Ezetimibe decreased the size of the endometriotic explants with its anti-inflammatory and anti-angiogenic properties. This agent alone or with combination of other agents may have a potential role in the treatment of endometriosis.

PPARγ Agonists: Emergent Therapy in Endometriosis

Endometriosis is one of the major gynecological diseases of reproductive-age women. This disease is characterized by the presence of glands and stroma outside the uterine cavity. Several studies have shown the major role of inflammation, angiogenesis, adhesion and invasion, and apoptosis in endometriotic lesions. Nevertheless, the mechanisms underlying endometriotic mechanisms still remain unclear and therapies are not currently efficient. The introduction of new agents can be effective by improving the condition of patients. PPARγ ligands can directly modulate these pathways in endometriosis. However, data in humans remain low. Thus, the purpose of this review is to summarize the potential actions of PPARγ agonists in endometriosis by acting on inflammation, angiogenesis, invasion, adhesion, and apoptosis.

Rosiglitazone affects the progression of surgically‑induced endometriosis in a rat model

Endometriosis is closely associated with inflammatory reactions and angiogenesis. Whether PPARγ is a target for the treatment of endometriosis remains unknown. The present study was designed to investigate the impact of a PPARγ agonist (rosiglitazone, RSG) on endometriosis in a rat model and to identify the underlying mechanism. The endometriosis model was established in rats. The pathological state of the endometrium was examined using hematoxylin‑eosin staining. The microstructures of interest were visualized using electron microscopy. Western blot analysis and reverse transcription‑quantitative polymerase chain reaction were used to detect PPARγ and MAT2A expression. VEGF and caspase‑3 expression were investigated using immunohistochemistry. Pathological analysis revealed transparent and red nodules in the model group, and that vasoganglions were present all over the nodules. Endometrial epithelial hyperplasia was observed in the model group, and the shape was columnar. Increased interstitial cell numbers, with compact structure and abundant blood supply, were detected in the model group. Compared with the model group, incomplete epithelial structures with sparse interstitial cells and loose structure were observed in the pathological images from RSG treatment groups. Numerous inflammatory cells and poor blood supply were observed in the endometrial tissues, and the gland was filled mostly with vacuolar cells. Electron microscopy revealed that the tissue structure was integrated. Many vacuoles were formed within the endometrial tissue and the classical morphological changes of apoptotic cells were observed in RSG‑treated groups. Caspase‑3 and PPARγ expression increased and expression of VEGF and MAT2A decreased in RSG‑treated groups. Taken together, these results revealed that RSG impacts the development and progression of endometriosis likely by inhibiting angiogenesis and inducing apoptosis.

Prenatal androgen excess alters the uterine peroxisome proliferator-activated receptor (PPAR) system

It is known that androgen excess induces changes in fetal programming that affect several physiological pathways. Peroxisome proliferator-activated receptors (PPARs) α, δ and γ are key mediators of female reproductive functions, in particular in uterine tissues. Thus, we aimed to study the effect of prenatal hyperandrogenisation on the uterine PPAR system. Rats were treated with 2mg testosterone from Day 16 to 19 of pregnancy. Female offspring (PH group) were followed until 90 days of life, when they were killed. The PH group exhibited an anovulatory phenotype. We quantified uterine mRNA levels of PPARα (Ppara ), PPARδ (Ppard ), PPARγ (Pparg ), their regulators peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Ppargc1a ) and nuclear receptor co-repressor 1 (Ncor1 ) and cyclo-oxygenase (COX)-2 (Ptgs2 ), and assessed the lipid peroxidation (LP) index and levels of glutathione (GSH) and prostaglandin (PG) E2 . The PH group showed decreased levels of all uterine PPAR isoforms compared with the control group. In addition, PGE2 and Ptgs2 levels were increased in the PH group, which led to a uterine proinflammatory environment, as was LP, which led to a pro-oxidant status that GSH was not able to compensate for. These results suggest that prenatal exposure to androgen excess has a fetal programming effect that affects the gene expression of PPAR isoforms, and creates a misbalanced oxidant-antioxidant state and a proinflammatory status.

Regression of experimental endometriotic implants in a rat model with the angiotensin II receptor blocker losartan

AIM

Endometriosis is a common disease in women of reproductive age, and many different treatments have been developed, although none has provided a cure. In this study, the efficacy of losartan, an angiotensin II type 1 receptor blocker and an antiangiogenic and anti-inflammatory agent, on regression of experimental endometriotic implants in a rat model was investigated.

METHODS

Peritoneal endometriosis was surgically induced in 16 mature female Sprague-Dawley rats. The peritoneal endometriotic implant was confirmed after 28 days, and the animals were divided randomly into two groups. The control group (n = 8) was given 4 mL/day tap water by oral gavage, and the losartan group (n = 8) was given 20 mg/kg per day losartan p.o. We compared endometriotic implant size, extent and severity of adhesion, as well as plasma and peritoneal lavage fluid cytokine levels including vascular endothelial growth factor (VEGF) and tumor necrosis factor (TNF)-α, plasma inflammatory factor pentraxin-3 (PTX-3) and C-reactive protein (CRP) between the treatment groups.

RESULTS

Mean surface endometriotic area, histological score of implants, adhesion formation, plasma VEGF, TNF, PTX-3 and CRP levels were significantly lower in the losartan group compared with control (P < 0.05). Furthermore, the peritoneal VEGF level was lower in the losartan group than in the control group (P < 0.001), but peritoneal TNF-α was similar in both groups (P > 0.05).

CONCLUSION

Losartan suppressed the implant surface area of experimental endometriosis in rats and reduced the levels of plasma VEGF, TNF-α, PTX-3 and CRP.

Medical treatments for endometriosis-associated pelvic pain

The main sequelae of endometriosis are represented by infertility and chronic pelvic pain. Chronic pelvic pain causes disability and distress with a very high economic impact. In the last decades, an impressive amount of pharmacological agents have been tested for the treatment of endometriosis-associated pelvic pain. However, only a few of these have been introduced into clinical practice. Following the results of the controlled studies available, to date, the first-line treatment for endometriosis associated pain is still represented by oral contraceptives used continuously. Progestins represent an acceptable alternative. In women with rectovaginal lesions or colorectal endometriosis, norethisterone acetate at low dosage should be preferred. GnRH analogues may be used as second-line treatment, but significant side effects should be taken into account. Nonsteroidal anti-inflammatory drugs are widely used, but there is inconclusive evidence for their efficacy in relieving endometriosis-associated pelvic pain. Other agents such as GnRH antagonist, aromatase inhibitors, immunomodulators, selective progesterone receptor modulators, and histone deacetylase inhibitors seem to be very promising, but there is not enough evidence to support their introduction into routine clinical practice. Some other agents, such as peroxisome proliferator activated receptors-γ ligands, antiangiogenic agents, and melatonin have been proven to be efficacious in animal studies, but they have not yet been tested in clinical studies.

The dynamics of nuclear receptors and nuclear receptor coregulators in the pathogenesis of endometriosis

BACKGROUND

Endometriosis is defined as the colonization and growth of endometrial tissue at anatomic sites outside the uterine cavity. Up to 15% of reproductive-aged women in the USA suffer from painful symptoms of endometriosis, such as infertility, pelvic pain, menstrual cycle abnormalities and increased risk of certain cancers. However, many of the current clinical treatments for endometriosis are not sufficiently effective and yield unacceptable side effects. There is clearly an urgent need to identify new molecular mechanisms that critically underpin the initiation and progression of endometriosis in order to develop more specific and effective therapeutics which lack the side effects of current therapies. The aim of this review is to discuss how nuclear receptors (NRs) and their coregulators promote the progression of endometriosis. Understanding the pathogenic molecular mechanisms for the genesis and maintenance of endometriosis as modulated by NRs and coregulators can reveal new therapeutic targets for alternative endometriosis treatments.

METHODS

This review was prepared using published gene expression microarray data sets obtained from patients with endometriosis and published literature on NRs and their coregulators that deal with endometriosis progression. Using the above observations, our current understanding of how NRs and NR coregulators are involved in the progression of endometriosis is summarized.

RESULTS

Aberrant levels of NRs and NR coregulators in ectopic endometriosis lesions are associated with the progression of endometriosis. As an example, endometriotic cell-specific alterations in gene expression are correlated with a differential methylation status of the genome compared with the normal endometrium. These differential epigenetic regulations can generate favorable cell-specific NR and coregulator milieus for endometriosis progression. Genetic alterations, such as single nucleotide polymorphisms and insertion/deletion polymorphisms of NR and coregulator genes, are frequently detected in ectopic lesions compared with the normal endometrium. These genetic variations impart new molecular properties to NRs and coregulators to increase their capacity to stimulate progression of endometriosis. Finally, post-translational modifications of NR coregulators, such as proteolytic processing, generate endometriosis-specific isoforms. Compared with the unmodified coregulators, these coregulator isoforms have unique functions that enhance the pathogenesis of endometriosis.

CONCLUSIONS

Epigenetic/genetic variations and posttranslational modifications of NRs and coregulators alter their original function so that they become potent 'drivers' of endometriosis progression.

Combined blockade of angiotensin II type 1 receptor and activation of peroxisome proliferator-activated receptor-γ by telmisartan effectively inhibits vascularization and growth of murine endometriosis-like lesions

STUDY QUESTION

Is telmisartan effective in the treatment of endometriosis?

SUMMARY ANSWER

Combined blockade of angiotensin II type 1 receptor (AT1R) and activation of peroxisome proliferator-activated receptor (PPAR)-γ by telmisartan inhibits vascularization and growth of murine endometriosis-like lesions.

WHAT IS KNOWN ALREADY

AT1R and PPAR-γ are involved in the regulation of inflammation, proliferation and angiogenesis. These processes are also crucial for the pathogenesis of endometriosis and both receptors are expressed in endometrial tissue. Telmisartan is a partial agonist of PPAR-γ, which additionally blocks AT1R.

STUDY DESIGN, SIZE, DURATION

This was a randomized study in the mouse dorsal skinfold chamber and peritoneal model of endometriosis. Endometriosis-like lesions were induced in dorsal skinfold chambers of 21 female C57BL/6 mice, and in the peritoneal cavity of 15 additional animals, which were daily treated with an i.p. injection of pioglitazone (10 mg/kg, n = 12), telmisartan (10 mg/kg, n = 12) or vehicle (5% dimethyl sulfoxide (DMSO), n = 12) throughout an observation period of 14 and 28 days, respectively.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The anti-angiogenic actions of pioglitazone, a full PPAR-γ agonist, and telmisartan were firstly assessed in vitro by an aortic ring assay. Endometriosis-like lesions were induced in the dorsal skinfold chamber or peritoneal cavity and the effects of telmisartan and pioglitazone on their vascularization, immune cell content and growth were studied by intravital fluorescence microscopy, high-resolution ultrasound imaging as well as histological, immunohistochemical and immunofluorescent analyses. Additional quantitative real-time polymerase chain reaction (qRT-PCR) arrays served for gene expression profiling of the lesions. To limit the role of chance, the experiments were conducted under standardized laboratory conditions with appropriate vehicle-treated controls. Statistical significance was accepted for a value of P < 0.05.

MAIN RESULTS AND THE ROLE OF CHANCE

Telmisartan inhibited vascular sprout formation of aortic rings more effectively than pioglitazone. Accordingly, endometriosis-like lesions in dorsal skinfold chambers of telmisartan-treated animals exhibited a markedly lower functional microvessel density and blood perfusion. High-resolution ultrasound analyses of peritoneal endometriosis-like lesions revealed that the compound inhibited the stromal tissue growth, resulting in a significantly reduced final lesion volume. In contrast, the development of cysts did not differ between the groups. Moreover, telmisartan induced an up-regulation of PPAR-γ and a down-regulation of AT1R proteins in endometriosis-like lesions, which was associated with a decreased density of CD31-positive microvessels, a reduced immune cell content and a lower number of Ki67-positive proliferating cells. qRT-PCR arrays further demonstrated an inhibitory action of telmisartan on the expression of several angiogenic and inflammatory genes.

LIMITATIONS, REASONS FOR CAUTION

Endometriosis-like lesions were induced by syngeneic tissue transplantation into recipient mice without the use of pathological endometriotic tissue of human nature. Therefore, the results obtained in this study may not fully relate to human patients with endometriosis.

WIDER IMPLICATIONS OF THE FINDINGS

This study demonstrates that telmisartan inhibits vascularization, immune cell content and growth of endometriosis-like lesions. Accordingly, the combined blockade of AT1R and activation of PPAR-γ represents a promising new concept in the development of novel compounds for the treatment of endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

There was no specific funding of this study. The authors have no conflicts of interest to declare.

PPARγ activation inhibits growth and survival of human endometriotic cells by suppressing estrogen biosynthesis and PGE2 signaling

Endometriosis is a chronic inflammatory disease of reproductive age women leading to chronic pelvic pain and infertility. Current antiestrogen therapies are temporizing measures, and endometriosis often recurs. Potential nonestrogenic or nonsteroidal targets are needed for treating endometriosis. Peroxisome proliferator-activated receptor (PPAR)γ, a nuclear receptor, is activated by thiazolidinediones (TZDs). In experimental endometriosis, TZDs inhibit growth of endometriosis. Clinical data suggest potential use of TZDs for treating pain and fertility concurrently in endometriosis patients. Study objectives were to 1) determine the effects of PPARγ action on growth and survival of human endometriotic epithelial and stromal cells and 2) identify the underlying molecular links between PPARγ activation and cell cycle regulation, apoptosis, estrogen biosynthesis, and prostaglandin E2 biosynthesis and signaling in human endometriotic epithelial and stromal cells. Results indicate that activation of PPARγ by TZD ciglitazone 1) inhibits growth of endometriotic epithelial cells 12Z up to 35% and growth of endometriotic stromal cells 22B up to 70% through altered cell cycle regulation and intrinsic apoptosis, 2) decreases expression of PGE2 receptors (EP)2 and EP4 mRNAs in 12Z and 22B cells, and 3) inhibits expression and function of P450 aromatase mRNA and protein and estrone production in 12Z and 22B cells through EP2 and EP4 in a stromal-epithelial cell-specific manner. Collectively, these results indicate that PGE2 receptors EP2 and EP4 mediate actions of PPARγ by incorporating multiple cell signaling pathways. Activation of PPARγ combined with inhibition of EP2 and EP4 may emerge as novel nonsteroidal therapeutic targets for endometriosis-associated pain and infertility, if clinically proven safe and efficacious.

PPAR-γ -- a possible drug target for complicated pregnancies

Peroxisome proliferator activated receptors (PPARs) are ligand-activated transcription factors expressed in trophoblasts, which regulate both cell differentiation and proliferation. In recent years, evidence has linked PPARs to playing an integral role in pregnancy; specifically, PPAR-β and PPAR-γ have been shown to play an integral role in placentation, with PPAR-γ additionally serving to regulate trophoblast differentiation. Recent evidence has shown that PPAR-γ expression is altered in many complications of pregnancy such as intrauterine growth restriction (IUGR), preterm birth, pre-clampsia and gestational diabetes. Thus, at present, accumulating evidence from the literature suggests both a pivotal role for PPAR-γ in the progression of a healthy pregnancy and the possibility that PPAR-γ may act as a therapeutic target in complicated pregnancies. This review aims to provide a succinct and comprehensive assessment of the role of PPAR-γ in normal pregnancy and pregnancy complications, and finally its potential as a therapeutic target in the treatment and/or prevention of adverse pregnancy outcomes.

Peroxisome proliferator-activated receptor γ agonist suppresses human telomerase reverse transcriptase expression and aromatase activity in eutopic endometrial stromal cells from endometriosis

Objective

To investigate the effect of peroxisome proliferator activated receptor γ (PPARγ) agonist on the cell proliferation properties and expression of human telomerase reverse transcriptase (hTERT) and aromatase in cultured endometrial stromal cell (ESC) from patients with endometriosis.

Methods

Human endometrial tissues were obtained from women with endometriosis and healthy women (controls) using endometrial biopsy. Isolated ESCs were cultured and the cell proliferation was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay and expression of hTERT, aromatase, and cyclooxygenase (COX)-2 by western blotting according to the addition of rosiglitazone (PPARγ agonist).

Results

We demonstrate that the cultured ESCs of endometriosis showed hTERT protein overexpression and increased cellular proliferation, which was inhibited by rosiglitazone, in a dose-dependent manner. At the same time, PPARγ agonist also inhibited aromatase and COX-2 expression, resulting in decreased prostaglandin E₂ production in the ESCs of endometriosis.

Conclusion

This study suggests that PPARγ agonist plays an inhibitory role in the proliferative properties of eutopic endometrium with endometriosis by down-regulation of hTERT and COX-2 expression; this could be a new treatment target for endometriosis.

New trends for the medical treatment of endometriosis

INTRODUCTION

Endometriosis is a benign sex hormone-dependent gynecological disease, characterized by the presence and growth of endometrial tissue outside the uterus; it affects 10% of women of reproductive age and is associated with infertility and pain. Treatment of endometriosis involves conservative or radical surgery, or medical therapies. The goals for endometriosis treatment may be the relief of pain and/or a successful pregnancy achievement in infertile patients. Treatment must be individualized with a multidisciplinary approach. The classical treatments carry adverse side effects and in some cases a negative impact on quality of life. New agents promise a distinct perspective in endometriosis treatment.

AREAS COVERED

The aim of this paper is to systematically review the literature evidence of new medical treatments for endometriosis, defined as pharmacological treatments not yet commonly available and currently under investigation.

EXPERT OPINION

These new medical therapies would be used associated with surgical treatment and, in the future, will render possible the association of hormone therapy with non-hormonal treatment for endometriosis.

The inhibitory effect of celecoxib and rosiglitazone on experimental endometriosis

OBJECTIVE

To evaluate the effects of celecoxib and rosiglitazone on the implantation and growth of endometriotic-like lesions in a murine model of endometriosis.

DESIGN

Prospective experimental study.

SETTING

Animal research and laboratory facility.

ANIMAL(S)

Two-month-old female BALB/c mice.

INTERVENTION(S)

Surgically induced endometriosis in female BALB/C mice; 28 days of treatment with celecoxib, rosiglitazone, or their combination; counting, measuring, excising, and fixing lesions.

MAIN OUTCOME MEASURE(S)

Immunohistochemical examination for proliferating cell nuclear antigen (PCNA), CD31, and CD34 to assess cell proliferation and vascularization, with the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) technique for apoptosis evaluation.

RESULT(S)

Celecoxib and the combined treatment (celecoxib and rosiglitazone) statistically significantly reduced the mean number of lesions established per mouse, and all treatments diminished the implant volume. In addition, cell proliferation within the implants was statistically significantly reduced, and apoptosis was statistically significantly enhanced by all treatments. Also, we found that all treatments diminished the vascularized area in the lesion.

CONCLUSION(S)

These results are promising and reveal that celecoxib and rosiglitazone, combined or separately, have a beneficial effect on overall endometriotic growth.

Peroxisome proliferator-activated receptor-(gamma) receptor ligand partially prevents the development of endometrial explants in baboons: a prospective, randomized, placebo-controlled study

A prospective, randomized, placebo-controlled study was conducted in a baboon model to determine if a thiazolidinedione agonist of peroxisome proliferator-activated receptor-gamma, pioglitazone, can impede the development of endometriosis. Endometriosis was induced using laparoscopic, intrapelvic injection of eutopic menstrual endometrium, previously incubated with placebo or pioglitazone for 30 min, in 12 female baboons with a normal pelvis that had undergone at least one menstrual cycle since the time of captivity. At this point, the 12 baboons were randomized into two groups and treated from the day of induction. They received either PBS tablets (n = 6, placebo control, placebo tablets once a day by mouth) or pioglitazone (n = 6, test drug, 7.5 mg by mouth each day). A second and final laparoscopy was performed in the baboons to record the extent of endometriotic lesions between 24 and 42 d after induction (no difference in length of treatment between the two groups, P = 0.38). A videolaparoscopy was performed to document the number and surface area of endometriotic lesions. The surface area and volume of endometriotic lesions were significantly lower in pioglitazone treated baboons than the placebo group (surface area, 48.6 vs. 159.0 mm(2), respectively, P = 0.049; vol, 23.7 vs. 131.8 mm(3), respectively, P = 0.041). The surface area (3.5 vs. 17.8 mm(2), P = 0.017, pioglizatone vs. placebo) and overall number (1.5 vs. 9.5, P = 0.007, pioglizatone vs. placebo) of red lesions were lower in the pioglitazone group. A peroxisome proliferator-activated receptor-gamma ligand, pioglitazone, effectively reduced the initiation of endometriotic disease in the baboon endometriosis model. Using this animal model, we have shown that thiazolidinedione is a promising drug for preventive treatment of endometriosis.

Peroxisome-proliferator activator receptor-gamma activation decreases attachment of endometrial cells to peritoneal mesothelial cells in an in vitro model of the early endometriotic lesion

The aim of this study was to investigate whether peroxisome proliferator-activated receptor (PPAR)-gamma activation has an effect on the attachment of endometrial cells to peritoneal mesothelial cells in a well-established in vitro model of the early endometriotic lesion. The endometrial epithelial cell line EM42 and mesothelial cell line LP9 were used for this study. EM42 cells, LP9 cells or both were treated with the PPAR-gamma agonist ciglitazone (CTZ) at varying concentrations (10, 20 and 40 microM) x 48 h with subsequent co-culture of EM42 and LP9 cells. The rate of EM42 attachment and invasion through LP9 cells was then assessed and compared with control (EM42 and LP9 cells co-cultured without prior treatment with CTZ). Next, attachment of CTZ-treated and untreated EM42 cells to hyaluronic acid (HA), a cell adhesion molecule (CAM) on peritoneal mesothelial cells, were assessed. Although there was no difference in EM42 attachment when LP9 cells alone were treated with CTZ, treatment of EM42 cells with 40 microM CTZ decreased EM42 attachment to LP9 cells by 27% (P < 0.01). Treatment of both EM42 and LP9 cells with 40 microM CTZ decreased EM42 attachment to LP9 by 37% (P < 0.01). Treatment of EM42 cells with 40 microM CTZ decreased attachment to HA by 66% (P = 0.056). CTZ did not decrease invasion of EM42 cells through the LP9 monolayer. CTZ may inhibit EM42 cell proliferation. In conclusion, CTZ significantly decreased EM42 attachment to LP9 cells and HA in an in vitro model of the early endometriotic lesion.

The role of iron in the pathogenesis of endometriosis

BACKGROUND

Endometriosis may cause symptoms including chronic pelvic pain and infertility, and increases susceptibility to the development of ovarian cancer. Genomic studies have started to delineate the wide array of mediators involved in the development of endometriosis. Understanding the mechanisms of endometriosis development and elucidating its pathogenesis and pathophysiology are intrinsic to prevention and the search for effective therapies.

METHOD OF STUDY

The present article reviews the English language literature for biological, pathogenetic and pathophysiological studies on endometriosis. Several recent genomic studies are discussed in the context of endometriosis biology.

RESULTS

Severe hemolysis occurring during the development of endometriosis results in high levels of free heme and iron. These compounds oxidatively modify lipids and proteins, leading to cell and DNA damage, and subsequently fibrosis development. Recent studies based on genome-wide expression analysis technology have noted specific expression of heme/iron-dependent mediators in endometriosis. The heme/iron-dependent signaling pathway of endometriosis, which is providing new insights into the regulation of inflammation, detoxification and survival, is discussed.

CONCLUSION

Several important endometriosis-specific genes overlap with those known to be regulated by iron. Other genes are involved in oxidative stress. Iron has a significant impact on endometriotic-cell gene expression. This review summarizes recent advances in the heme/iron-mediated signaling and its target genes, outlines the potential challenges to understanding of the pathogenesis and pathophysiology of endometriosis, and proposes a possible novel model.

New drugs in development for the treatment of endometriosis

Endometriosis is a common and enigmatic disease causing pelvic pain and infertility. Current treatment is mainly based on the use of surgery and ovarian suppressive agents. There is in particular the need for new therapeutic options able to allow a normal menstrual cycle to occur and also consent pregnancy. In the present review, we aimed to give a concise and practical overview in order to allow the clinician to clearly understand the level of development of these drugs. We have presented only treatments supported by in vivo researches with a special attention to studies in humans. Results show appealing new possibilities are emerging from agents counteracting the endometriosis-associated inflammation. Recent data also suggests that there is still the opportunity to refine the use of already available agents.

Peroxisome proliferator-activated receptor-gamma and retinoid X receptor agonists synergistically suppress proliferation of immortalized endometrial stromal cells

OBJECTIVE

To examine whether trichostatin A (TSA), a histone deacetylase inhibitor (HDACI), can induce up-regulation of peroxisome proliferator-activating receptor gamma (PPAR gamma) and to see whether LG100268, a retinoid X receptor (RXR) ligand, can inhibit proliferation of endometriotic cells alone or in synergy with ciglitazone, a PPAR gamma agonist.

DESIGN

One endometrial stromal cell line and two endometriotic cell lines used as a model system: Western blot analysis to determine whether TSA can up-regulate PPAR gamma expression, and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) proliferation assay to see whether ciglitazone and LG100268 have any antiproliferative effects individually or jointly.

SETTING

Academic.

PATIENT(S)

None.

INTERVENTION(S)

Culture of immortalized endometrial and endometriotic cell lines with TSA, or ciglitazone or LG100268.

MAIN OUTCOME MEASURE(S)

PPAR gamma protein expression levels in cells treated with or without TSA, and number of viable cells treated with or without ciglitazone, LG100268, or both.

RESULT(S)

The TSA treatment resulted in up-regulation of PPAR gamma expression in all cell lines in a dose-dependent fashion. Both ciglitazone and LG100268 inhibited proliferation in a dose-dependent manner, and the antiproliferative effects appeared to be synergistic. In addition, endometriotic cells were more sensitive than endometrial stromal cells to LG100268 treatment.

CONCLUSION(S)

The up-regulation of PPAR gamma induced by TSA indicates that the action of HDACIs also includes the PPAR gamma signaling pathway, suggesting that the activation of PPAR gamma is a desirable way to contain endometriosis phenotypes. The higher sensitivity of endometriotic cells than their endometrial counterpart to LG100268 treatment suggests that the sensitivity differential could be exploited effectively to eradicate unwanted ectopic endometrial tissues while minimizing the collateral damage to the normal endometrial tissues.