Immunomodulation of rat endometriotic implant growth and protein production

Immunomodulation in Endometriosis: Investigating the interrelationship between VISTA expression and Escherichia.Shigella-Associated metabolites

AIMS

Endometriosis is characterized by an abnormal immune microenvironment. Despite the extensive use of immune therapies, the application of immune checkpoint inhibitors in endometriosis lacks confidence due to the instability of preclinical research data. This study aims to elucidate the regulation of the immune inhibitory checkpoint VISTA and its effects on T cells from the perspective of microbiota and metabolism.

MAIN METHODS

We divided endometriosis patients into high and low groups based on the expression levels of VISTA in lesion tissues. We collected peritoneal fluid samples from these two groups and performed 16 s RNA sequencing and metabolomics analysis to investigate microbial diversity and differential metabolites. Through combined analysis, we identified microbial-associated metabolites and validated their correlation with VISTA and CD8 + T cells using ELISA and immunofluorescence. In vitro experiments were conducted to confirm the regulatory relationship among these factors.

KEY FINDINGS

Our findings revealed a distinct correlation between VISTA expression and the microbial colony Escherichia.Shigella. Moreover, we identified the metabolites LTD4-d5 and 2-n-Propylthiazolidine-4-carboxylic acid as being associated with both Escherichia.Shigella and VISTA expression. In vitro experiments confirmed the inhibitory effects of these metabolites on VISTA expression, while they demonstrated a positive regulation of CD8 + T cell infiltration into endometriotic lesions.

SIGNIFICANCE

This study reveals the connection between microbial diversity, metabolites, and VISTA expression in the immune microenvironment of endometriosis, providing potential targets for therapeutic interventions.

Immunotherapy: A promising novel endometriosis therapy

Endometriosis is a common disease of the female reproductive system and has malignant features. Although endometriosis by itself is a benign disease, its erosive growth characteristics lead to severe pelvic pain and female infertility. Unfortunately, several aspects of the pathogenesis of endometriosis are still unclear. Furthermore, the clinical therapeutic methods are unsatisfactory. The recurrence rate of endometriosis is high. Accumulating evidence suggests that the onset and development of endometriosis are closely related to the abnormal function of the female autoimmune system, especially the function of some immune cells such as the aggregation of neutrophils, abnormal differentiation of macrophages, decreased cytotoxicity of NK cells, and abnormal function of T- and B-cell lines. Therefore, immunotherapy is probably a novel therapeutic strategy for endometriosis besides surgery and hormone therapy. However, information regarding the clinical application of immunotherapy in the treatment of endometriosis is very limited. This article aimed to review the effects of existing immunomodulators on the development of endometriosis, including immune cell regulators and immune factor regulators. These immunomodulators clinically or experimentally inhibit the pathogenesis and development of endometriosis lesions by acting on the immune cells, immune factors, or immune-related signaling pathways. Thus, immunotherapy is probably a novel and effective clinical treatment choice for endometriosis. Experimental studies of the detailed mechanism of immunotherapy and large-scale clinical studies about the effectiveness and safety of this promising therapeutic method are required in the future.

The Link Between Stress and Endometriosis: from Animal Models to the Clinical Scenario

There is strong evidence from humans and animal models showing that abnormal functioning of the hypothalamic-pituitary-adrenal (HPA) axis and/or the inflammatory response system disrupts feedback regulation of both neuroendocrine and immune systems, contributing to disease. Stress is known to affect the physiology of pelvic organs and to disturb the HPA axis leading to chronic, painful, inflammatory disorders. A link between stress and disease has already been documented for many chronic conditions. Endometriosis is a complex chronic gynecological disease associated with severe pelvic pain and infertility that affects 10% of reproductive-aged women. Patients report the negative impact of endometriosis symptoms on quality of life, work/study productivity, and personal relationships, which in turn cause high levels of psychological and emotional distress. The relationship between stress and endometriosis is not clear. Still, we have recently demonstrated that stress increases the size and severity of the lesions as well as inflammatory parameters in an animal model. Furthermore, the "controllability" of stress influences the pathophysiology in this model, offering the possibility of using stress management techniques in patients. The crosstalk between stress-inflammation-pain through HPA axis activity indicates that stress relief should alleviate inflammation and, in turn, decrease painful responses. This opens up the opportunity of altering brain-body-brain pathways as potential new therapeutic option for endometriosis. The goal of this review is to gather the research evidence regarding the interaction between stress (psychological and physiological) and the development and progression of endometriosis on the exacerbation of its symptoms with the purpose of proposing new lines of emerging research and possible treatment modalities for this still incurable disease.

Short treatment with antalarmin alters adrenal gland receptors in the rat model of endometriosis

Endometriosis is a chronic inflammatory disorder in which endometrial tissue is found outside the uterine cavity. Previous reports suggest that there is a dysregulation of the hypothalamic pituitary adrenal axis during the progression of endometriosis. Our previous report showed that a short-term treatment with antalarmin, a corticotrophin releasing hormone receptor type 1 (CRHR1) antagonist decreases the number and size of endometriotic vesicles in the auto-transplantation rat model of endometriosis. Our current goal was to examine the mRNA expression of intra-adrenal receptors to better understand the mechanisms of the hypothalamic pituitary adrenal (HPA) axis involvement in endometriosis. We used two groups of female rats. The first received sham surgery or endometriosis surgery before collecting the adrenals after 7 days of the disease progression. The second group of animals received endometriosis surgery and a treatment of either vehicle or antalarmin (20 mg/kg, i.p.) during the first 7 days after endometriosis induction and then the disease was allowed to progress until day 60. Rats with sham surgery served as controls. Results showed that the mRNA expression of the mineralocorticoid (MRC2) receptor was lower in the rats after 7 days of endometriosis surgery and in rats with endometriosis that received antalarmin. In addition, the CRHR1 was significantly elevated in animals that received antalarmin and this was counteracted by a non-significant elevation in CRHR2 mRNA. The glucocorticoid receptor mRNA within the adrenals was not affected by endometriosis or antalarmin treatment. This report is one of the first to explore intra-adrenal mRNA for receptors involved in the HPA axis signaling as well as in the sympatho-adrenal signaling, calling for additional research towards understanding the role of the adrenal glands in chronic inflammatory diseases such as endometriosis.

Chronic Niche Inflammation in Endometriosis-Associated Infertility: Current Understanding and Future Therapeutic Strategies

Endometriosis is an estrogen-dependent inflammatory disease that affects up to 10% of women of reproductive age and accounts for up to 50% of female infertility cases. It has been highly associated with poorer outcomes of assisted reproductive technology (ART), including decreased oocyte retrieval, lower implantation, and pregnancy rates. A better understanding of the pathogenesis of endometriosis-associated infertility is crucial for improving infertility treatment outcomes. Current theories regarding how endometriosis reduces fertility include anatomical distortion, ovulatory dysfunction, and niche inflammation-associated peritoneal or implantation defects. This review will survey the latest evidence on the role of inflammatory niche in the peritoneal cavity, ovaries, and uterus of endometriosis patients. Nonhormone treatment strategies that target these inflammation processes are also included. Furthermore, mesenchymal stem cell-based therapies are highlighted for potential endometriosis treatment because of their immunomodulatory effects and tropism toward inflamed lesion foci. Potential applications of stem cell therapy in treatment of endometriosis-associated infertility in particular for safety and efficacy are discussed.

Leflunomide—an Immunomodulator—Induces Regression of Endometrial Explants in a Rat Model of Endometriosis

OBJECTIVE

To test if leflunomide, an immunomodulator, could impede the growth of an ectopic uterine tissue.

METHODS

Endometriosis was surgically induced in 26 rats by transplanting an autologous fragment of endometrial tissue onto the inner surface of the abdominal wall. Four weeks later two rats were killed. The volume and weight of the implants were measured. The remaining rats were randomly grouped, and in group 1 no medication was given. To the rats in group 2, 35 mg/kg/d of leflunomide was administered orally. Four weeks later, rats were killed and ectopic uterine tissues were reevaluated morphologically and histologically. A scoring system was used to evaluate preservation of epithelia.

RESULTS

Two rats in the control group died 5 weeks after surgery. There was a significant difference in post-treatment spherical volumes (139.1 +/- 92.8 versus 33.5 +/- 12.5 mm3) and explant weights (156.3 +/- 105.6 versus 38.6 +/- 12.6 mg) between the control and leflunomide-treated groups. The epithelia were found to be preserved significantly better in the control group when compared with the leflunomide-treated group (median 2.5 [interquartile range, 1.25] versus median 1.00 [interquartile range, 1.5]).

CONCLUSION

Leflunomide appeared to cause regression of experimental endometriosis in rats.

Immunological aspects of endometriosis: a review

Endometriosis is a common and serious illness affecting women in their reproductive years. Despite the ongoing interest and intensive research of this crippling disease, the cause remains unknown since its first description over 150 years ago. The origins and genesis of endometriosis, despite numerous hypotheses, are still unclear. One of the possible causes of the development of endometriosis might be the immune system, despite the fact that endometriosis is generally considered to be a steroid-sensitive disease. Numerous aspects of the immune system has been found changed, from the different number of activated macrophages to different subtypes of lymphocytes and their activities, suggesting involvement of immunity. On the other hand, it is possible that immunological changes around the endometriotic lesion are only secondary to the establishment of endometriosis. In this review, we will summarize the current knowledge of immunological reactions in endometriosis.

An overview of the current status of clinical trials on endometriosis: issues and concerns

OBJECTIVE

To examine and compare differences, if any, between industry- and nonindustry-sponsored clinical trials on endometriosis and to evaluate the effect of prior published positive preclinical results, or lack thereof, on trial status.

DESIGN

Cross-sectional study of clinical trials on endometriosis that evaluate drugs/biologicals registered at ClinicalTrials.gov as of July 3, 2013.

SETTING

University-affiliated hospital.

PATIENT(S)

None.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Trial status, size, phase, and duration; use of comparator groups; drug classes, number of arms, targeting conditions; and presence or absence of prior positive preclinical results before the launch of the trial.

RESULT(S)

Eighty trials were identified. The trials sponsored by industry and non-industry have distinct features, differing in trial status, phase, comparator, drug classes, number of arms, trial size, and duration. The phase II/III trials are predominantly industry supported, but these trials frequently use placebo as the comparator. Trials launched without prior published preclinical results do not seem to fare well, although the presence of such studies is no guarantee for success.

CONCLUSION(S)

Questions as to whether the drug on trial is truly superior to the best available drug or of its cost-benefit profile are overlooked in most cases. There seems to be a deluge of "me-too" drugs with equivocal superiority over existing drugs and cost-benefit profiles. Because clinical trials are time-consuming, no blockbuster drug for endometriosis seems to be on the horizon yet.

An update on the pharmacological management of endometriosis

INTRODUCTION

Endometriosis is a common disease that causes pain symptoms and/or infertility in women in their reproductive years. The disease is characterised by the presence of endometrium-like tissue - glands and stroma - outside the uterine cavity. Different treatment options exist for endometriosis including medical and surgical treatments or a combination of the two approaches. The most commonly used medications are non-steroidal anti-inflammatory drugs, GnRH agonists, androgen derivatives such as danazol, combined oral contraceptive pills, progestogens and more recently the levonorgestrel intrauterine system.

AREAS COVERED

The authors review current medical treatments used for symptomatic endometriosis and also discuss new treatment approaches. The authors conducted a literature search for randomised controlled trials related to medical treatments of endometriosis in humans, searched the Cochrane library for reviews and also searched for registered trials that have not yet been published on ClinicalTrials.gov.

EXPERT OPINION

The medical treatment of endometriosis is effective at treating pain and preventing recurrence of disease after surgery. Remarkably, the oral contraceptive pill taken continuously is as effective as GnRH-a, while causing far less side-effects. Conversely, no treatment currently exists for enhancing fecundity in women whose infertility is associated with endometriosis. As all existing therapies of endometriosis are contraceptive, great efforts should be targeted at researching novel products that reduce the disease expression without shuttering ovulation.

New treatment strategies and emerging drugs in endometriosis

Introduction: Endometriosis, histologically defined as the presence of endometrium-like tissue - glands and stroma - that develops outside of the uterine cavity, is still an enigmatic disease responsible for pelvic pain and infertility. The current treatments of endometriosis are surgery and hormonal therapies that act by suppressing ovulation and/or directly on steroid receptors located in endometriotic lesions. Areas covered: New hormonal and non-hormonal therapies are being developed for the treatment of endometriosis-related pain. The authors review the state of advancement and the results of novel treatments studied in registered trials ( www.ClinicalTrials.gov ). Cellular signaling pathways activated in endometriotic cells, which constitute potential targets for future treatments, are also described. Expert opinion: Therapeutic research efforts should focus on identifying and testing substances capable of acting locally on the lesions themselves, without interfering with ovulation, in order to be efficacious on both pain symptoms and infertility.

Pentoxifylline for endometriosis

BACKGROUND

Endometriosis is a chronic, recurring condition that occurs during the reproductive years. It is characterized by endometrial tissue developing outside the uterine cavity. This endometrial tissue development is dependent on oestrogen produced primarily by the ovaries and, therefore, traditional management has focused on ovarian suppression. In this review we considered the role of modulation of the immune system as an alternative approach. This is an update of a Cochrane Review previously published in 2009 (Lu 2009).

OBJECTIVES

To assess the effects of pentoxifylline, which has anti-inflammatory effects, in subfertile, premenopausal women for the management of endometriosis.

SEARCH METHODS

For the first publication of this review we searched the following databases (from inception to December 2008) for trials: Cochrane Menstrual Disorders and Subfertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, CINAHL, and PsycINFO. In addition, all reference lists of included trials were searched and experts in the field were contacted in an attempt to locate trials. This search was rerun to 23 November 2011, for this update.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing pentoxifylline with placebo or no treatment, medical treatment, or surgery in subfertile, premenopausal women were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial risk of bias, and extracted data using data extraction forms. We contacted study authors for additional information and data. The domains assessed for risk of bias were sequence generation, allocation concealment, blinding, incomplete outcome data, and selective outcome reporting. Peto odds ratios (OR) were used for reporting dichotomous data with 95% confidence intervals (CI), whilst mean differences (MD) were expressed for continuous data. Statistical heterogeneity was assessed using the I(2) statistic.

MAIN RESULTS

Four trials involving 334 participants were included. One RCT [n=34] showed pentoxifylline had no significant effect on reduction in pain (MD -1.60, 95% CI -3.32 to 0.12). There was no evidence of an increase in clinical pregnancy events in the pentoxifylline group compared with placebo (three RCTs [n=67] OR 1.54, 95% CI 0.89 to 266). One RCT studied recurrence of endometriosis [n=88] (OR 0.88,95% CI 0.27 to 2.84). No trials reported the effects of pentoxifylline on the odds of live birth rate per woman, improvement of endometriosis-related symptoms, or adverse events.

AUTHORS' CONCLUSIONS

This review has been updated in 2011. The results of the original review published in 2009 remain unchanged. There is still not enough evidence to support the use of pentoxifylline in the management of premenopausal women with endometriosis in terms of subfertility and relief of pain outcomes.

Pentoxifylline versus medical therapies for subfertile women with endometriosis

BACKGROUND

Endometriosis is a chronic, recurring condition that occurs during the reproductive years. It is characterized by endometrial tissue developing outside the uterine cavity. This endometrial tissue development is dependent on estrogen produced primarily by the ovaries and, therefore, traditional management has focused on ovarian suppression. In this review we considered the role of modulation of the immune system as an alternative approach.

OBJECTIVES

To determine the effectiveness and safety of pentoxifylline, which has anti-inflammatory effects, in the management of endometriosis in subfertile, premenopausal women.

SEARCH STRATEGY

We searched the following databases (from inception to December 2008) for trials: Cochrane Menstrual Disorders and Subfertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE, EMBASE, CINAHL, and PsycINFO. In addition, all reference lists of included trials were searched and experts in the field were contacted in an attempt to locate trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing pentoxifylline with placebo or no treatment, medical treatment, or surgery in subfertile, premenopausal women were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial quality, and extracted data using data extraction forms. We contacted study authors for additional information and data. The domains assessed for risk of bias were sequence generation, allocation concealment, blinding, incomplete outcome data, and selective outcome reporting. Odds ratios (OR) were used for reporting dichotomous data with 95% confidence intervals (CI), whilst mean differences (MD) were expressed for continuous data. Statistical heterogeneity was assessed using the I(2) statistic.

MAIN RESULTS

Four trials involving 334 participants were included. Results showed pentoxifylline had no significant effect on reduction in pain (one RCT, MD -1.60, 95% CI -3.32 to 0.12). There was no evidence of an increase in clinical pregnancy events in the pentoxifylline group compared with placebo (three RCTs, OR 1.54, 95% CI 0.89 to 266). For recurrence of endometriosis, one RCT reported an OR of 0.88 (95% CI 0.27 to 2.84). No trials reported the effects of pentoxifylline on the odds of live birth rate per woman, improvement of endometriosis-related symptoms, or adverse events.

AUTHORS' CONCLUSIONS

There is not enough evidence to support the use of pentoxifylline in the management of premenopausal women with endometriosis in terms of subfertility and relief of pain outcomes.

Effect of pentoxifylline on vascular endothelial growth factor C and flk-1 expression on endometrial implants in the rat endometriosis model

OBJECTIVE

To investigate the effects of pentoxifylline, on vascular endothelial growth factor (VEGF)-C and flk-1 expression in the rat endometriosis model.

DESIGN

Prospective, randomized, placebo-controlled study.

SETTING

Academic institution.

ANIMAL(S)

Twenty Wistar rats with surgically induced endometriosis.

INTERVENTION(S)

Animals were evaluated after surgical induction of endometriosis and random allocation to a group that received pentoxifylline and a control group that received NaCl 0.9%, for 3 weeks. At the end of the treatment period the animals were killed and the implants evaluated macroscopically as well as by immunohistochemistry.

MAIN OUTCOME MEASURE(S)

Morphologic changes of the endometriotic implants; and evaluation of VEGF-C and flk-1 expression by a semiquantitative analysis (HSCORE) for the intensity of immunohistochemical reactivity.

RESULT(S)

A significant reduction was observed in the mean volume of the endometriotic implants per animal in the treatment group as compared with the control group. There was a significant reduction not only in the mean volume of implants per animal but also in the mean number of implants per animal after treatment. By immunohistochemical evaluation (HSCORE), there was a significant reduction in VEGF-C expression after treatment in all areas examined. A significant reduction of flk-1 expression was also noted in the glandular compartment after treatment but not in the epithelial surface or stroma.

CONCLUSION(S)

Pentoxifylline may cause suppression of endometriotic lesions by suppressing angiogenesis through VEGF-C and flk-1 expression.

Combined laparoscopic surgery and pentoxifylline therapy for treatment of endometriosis-associated infertility: a preliminary trial

BACKGROUND

Surgical treatment has modest efficacy for the treatment of infertility associated with early-stage endometriosis. Immunomodulation with pentoxifylline is considered as a new strategy potentially useful in treating endometriosis. Thus, this study investigated the usefulness of combined laparoscopic surgery and pentoxifylline therapy in the treatment of infertility associated with minimal to mild endometriosis.

METHODS

A prospective, randomized, controlled blind trial was conducted. Patients entered the study immediately after laparoscopic surgery and were randomly assigned to the treatment with either oral pentoxifylline (800 mg/day) (pentoxifylline group, n = 51) or an oral placebo (placebo group, n = 53). Patients were then observed for pregnancy for 6 months.

RESULTS

Among 98 patients finally considered in the evaluation of the results, the 6 month overall pregnancy rates were 28 and 14% in the pentoxifylline and placebo groups, respectively. Thus, an absolute difference of 14% (95% CI -2 to 30) (Chi-squared test, P = 0.1) in the cumulative probability of pregnancy in 6 months after laparoscopic surgery in patients receiving pentoxifylline versus placebo post-operatively was observed.

CONCLUSION

Our findings provide preliminary clinical evidence to suggest the new experimental treatment approaches, toward endometriosis, that are based on immunomodulation deserve further attention. Well-designed multicenter trials are warranted to confirm or refute our results.

PPAR-gamma receptor ligand induces regression of endometrial explants in baboons: a prospective, randomized, placebo- and drug-controlled study

OBJECTIVE

To determine the effects of a thiazolidinedione (TZD) agonist of peroxisome proliferator-activated receptor (PPAR)-gamma, rosiglitazone, in a baboon model of established endometriosis.

DESIGN

Prospective, randomized, placebo-controlled study.

SETTING

Experimental surgery laboratory at the Institute of Primate Research in Nairobi, Kenya.

ANIMAL(S)

Endometriosis was induced using intrapelvic injection of eutopic menstrual endometrium in 12 female baboons with a normal pelvis that had undergone at least one menstrual cycle since the time of captivity.

INTERVENTION(S)

Induction of endometriosis by laparoscopy was performed in 12 baboons with a normal pelvis. Endometrial tissue was extracted from each baboon by curettage, and a standard amount of endometrium was then seeded onto several peritoneal sites. About 34-68 days after the induction of laparoscopy, a pretreatment laparoscopy (baseline disease assessment) was performed in the baboons to record the extent of endometriotic lesions. The 12 baboons were randomized into three groups and treated from the day after the staging laparoscopy for a total duration of 30 days. They received phosphate-buffered saline tablets (n = 4, placebo control; placebo tablets once a day by mouth for 30 days), GnRH-antagonists (n = 4, active control; ganirelix acetate 125 microg/day for 30 days), or rosiglitazone (n = 4, test drug, 2 mg by mouth each day for 30 days). A third and final laparoscopy on day 30 after the start of treatment was performed to record the extent of endometriosis. The type of lesion (typical, red, white, or suspicious) was recorded. Biopsies were obtained to confirm the histological presence of endometriosis.

MAIN OUTCOME MEASURE(S)

A videolaparoscopy was performed 30 days after treatment to document the number and surface area of endometriotic lesions as well as to calculate the revised American Society for Reproductive Medicine score and stage.

RESULT(S)

The surface area of endometriotic lesions was statistically significantly lower in rosiglitazone-treated baboons when compared with the placebo group. Baboons treated with rosiglitazone or ganirelix had a greater negative relative change in surface area of peritoneal endometriotic lesions than controls. The overall weighted appearance of the lesion types suggests that rosiglitazone may deter the development of newer endometriotic lesions.

CONCLUSION(S)

A PPAR-gamma ligand, rosiglitazone, effectively diminishes the burden of endometriosis disease in a baboon endometriosis model. This animal model holds promise that a TZD drug may be helpful in women with endometriosis.

Pentoxifylline therapy after laparoscopic surgery for different stages of endometriosis: a prospective, double-blind, randomized, placebo-controlled study

STUDY OBJECTIVE

To evaluate the effects of pentoxifylline administration on patients with different stages of endometriosis on whom laparoscopy was performed.

DESIGN

Prospective, double-blind, randomized, placebo-controlled clinical (Canadian Task Force classification I).

SETTING

University and private hospitals.

PATIENTS

Eighty-eight women, all with infertility, some with dysmenorrhea, dyspareunia, or pelvic pain, on whom a laparoscopic diagnosis of endometriosis was made.

INTERVENTIONS

The treatment group received 800 mg pentoxifylline daily for 6 months immediately after surgery. The control group received placebo capsules. All patients were followed-up for 1 year thereafter.

MEASUREMENTS AND MAIN RESULTS

A comparison of pregnancy rate and recurrence of signs and symptoms in the 2 groups was performed. Forty-three patients were studied in the pentoxifylline group and 45 in the placebo group. The cumulative pregnancy rate was 39.5% and 35.6% in the treatment and control groups, respectively. The overall recurrence of signs and symptoms was 14% in the former group and 15.6% in the latter. There were no statistically significant differences between the 2 groups in rates of pregnancy and recurrence (p = .700 and .832, respectively). Nor was there any significant statistical difference between the same stages in the 2 groups regarding immunomodulation.

CONCLUSIONS

According to the results of this study, and while keeping in mind that appropriate surgery is the main aspect of endometriosis treatment, there is no evidence that immunomodulation with pentoxifylline aids fertility or lessens recurrence of signs and symptoms in women with different stages of endometriosis (i.e., minimal, mild, moderate, or severe).

FR 167653, a p38 mitogen-activated protein kinase inhibitor, suppresses the development of endometriosis in a murine model

In various cells including endometriotic cells, p38 mitogen-activated protein kinase (MAPK) plays essential roles for inflammation, an etiological factor for endometriosis. We evaluated the effect of FR 167653, a p38 MAPK inhibitor, on the development of endometriosis using a murine model. As an endometriosis model, estradiol-treated ovariectomized BALB/c mice were injected intraperitoneally with endometrial fragments of the syngenic donor mice. The animals were injected with either 30mg/kg FR 167653 or only vehicle (control) s.c. twice a day, starting 2 days before endometrial injection. Three weeks later, the peritoneal fluids and the developed endometriotic lesions were collected. Both the weight of all the endometriotic lesions per mouse and the concentrations of interleukin-6 and monocyte chemoattractant protein-1 in the peritoneal fluid were significantly lower in the FR 167653-treated mice than in the control mice. These findings suggest that FR 167653 may inhibit the development of endometriosis possibly by suppressing peritoneal inflammatory status.

Animal models in endometriosis research

Endometriosis is a common gynaecological disease, defined as the presence of endometrial tissue outside the uterus, causing pelvic pain and subfertility in approximately 10% of women of reproductive age. Current therapies lead to pain relief, however, do not address the causes and entail severe side effects. Still little is known about the pathogenic processes leading to the development and maintenance of endometriosis. Because endometriosis occurs spontaneously only in humans and some non-human primates, animal models of induced endometriosis have been developed and are of high value for the evaluation of pathophysiological mechanisms underlying the development of this disease. These experimental models include the autotransplantation of uterine fragments into the peritoneal cavity of rodents and non-human primates or the heterotransplantation of human endometrial or endometriotic tissue to immunodeficient mice or onto the chicken chorioallantoic membrane (CAM). This review describes the animal models for endometriosis and assesses their different potentials and limitations in regard to endometriosis research, with the aim of developing novel non-invasive diagnostic tools and improved strategies for the treatment of endometriosis in women.

Effect of BCG vaccine on peritoneal endometriotic implants in a rat model of endometriosis

OBJECTIVE

To investigate the effect of Bacillus Calmette-Guerin (BCG) vaccine on peritoneal implantation of endometrial tissue in rats.

METHODS

Forty sexually mature virgin Wistar albino rats weighing 190-200 g were randomly assigned (double blind) to two groups. The rats in the first group were vaccinated with 0.1 mL BCG and those in the second group were injected with 0.1 mL saline into the tail, intracutaneously. All the rats underwent median laparotomy after 4 weeks of vaccination or injection. The right uterine horn was excised, and the two samples of endometrial tissue dissected from myometrium were implanted on each side of peritoneum at the 2 cm lateral line of the median laparotomy incision. The implanted peritoneal segments were excised after 8 weeks of laparotomy. The tissue samples were accepted, histologically, as endometriosis when both glands and stroma of endometrial tissue were seen in sections.

RESULTS

Thirty-six implants from the study group and 34 implants from the control group were obtained. Ten and 23 implants were accepted as endometriosis in the study and control group, respectively. The number of endometriotic foci were significantly lower in the study group than in the control group (P = 0.01).

CONCLUSIONS

Stimulation of the cellular immune response with BCG vaccine could exert an inhibitory effect on ectopic endometriotic implants.

Future Perspectives in the Medical Treatment of Endometriosis

In the last few years, our understanding of the pathogenesis of endometriosis at the cellular and molecular levels has improved significantly. This may give us the opportunity to use new, specific agents for the treatment of this disorder. Despite the effectiveness of the available treatments, novel therapeutic strategies may improve our ability to eliminate endometriotic lesions when present and to prevent the recurrence of endometriosis after surgical treatment. This review focuses on the new, experimental approaches to the medical treatment of endometriosis and its symptoms. The blockage of aromatase activity in endometriotic lesions with an aromatase inhibitor may represent a new step in the medical treatment of endometriosis. Preliminary clinical studies have demonstrated the efficacy of third-generation nonsteroidal aromatase inhibitors (ie, anastrozole and letrozole) in reducing the intensity of pain symptoms associated with the presence of endometriosis. The new selective progesterone receptor modulators may represent a valid hormonal treatment option. Therapeutic manipulation of the immune system through TNFalpha inhibitors may be beneficial in women with endometriosis. New pharmaceutical agents affecting inflammation, angiogenesis, and matrix metalloproteinase activity may prevent or inhibit the development of endometriosis. Further clinical trials may determine if these new therapies are superior to current medical treatment strategies for endometriosis.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians Learning.

OBJECTIVES

After completion of this article, the reader should be able to describe the new experimental medical treatments of endometriosis, state that the clinical use of nonsteroidal aromatase inhibitors for endometriosis appears to be efficacious but is based on preliminary clinical data, and recall that the drugs used for endometriosis in the future may include manipulation of the immune system.

Novel targets for the treatment of endometriosis

Endometriosis is an enigmatic, debilitating disease that affects up to 15% of all women of reproductive age. It is characterised by pelvic pain and infertility. Current treatment regimens control the disease by inducing a hypoestrogenic state. Although the absence of circulating oestrogen levels leads to a regression of the disease, this hypoestrogenism also induces many unpleasant side effects. As such, these and other shortcomings of current drug therapies emphasise their limitations and the necessity for the development of novel endometriosis treatments. In this review, current therapies for medical management of endometriosis are discussed, as are their shortcomings. Potential target areas that may be attractive alternatives to current therapies are also reviewed. Emphasis is placed upon the emerging research using TNF inhibitors, their potential benefits over current treatment regimens and the development of future potential therapeutic targets.

Peroxisome proliferator-activated receptor-gamma induces regression of endometrial explants in a rat model of endometriosis

OBJECTIVE

To determine the effects of a thiazolidinedione, ciglitazone, in a rat model of endometriosis.

DESIGN

Prospective, randomized, placebo-controlled study.

SETTING

Experimental surgery laboratory in a university department.

ANIMAL(S)

Twenty female Sprague-Dawley rats given endometriotic lesions by transplanting autologous uterine tissue to ectopic sites on the peritoneum.

INTERVENTION(S)

Four weeks after surgery, 20 rats were randomly divided into two groups and treated with IP injections of vehicle every other day (control; n = 10) or ciglitazone (1 mg per rat; n = 10) and euthanized 4 weeks from the start of treatment.

MAIN OUTCOME MEASURE(S)

At the end of treatment, laparotomy was performed to photograph each explant and then they were measured and weighed. Histologic analysis was performed on the uterine allograft, ovary, and eutopic uterine tissue.

RESULT(S)

By histologic assessment, both groups maintained folliculogenesis and normal eutopic endometrial architecture. Treatment with ciglitazone significantly decreased the size of ectopic uterine tissues and the mean explant wet weight. The ciglitazone-treated group showed marked epithelial regression compared with the control group.

CONCLUSION(S)

We conclude that a PPAR-gamma ligand, ciglitazone, reduced the size of experimental endometriosis in the rat model of endometriosis. This animal model suggests that a thiazolidinedione drug may be helpful in women with endometriosis.

Altered expression of interleukin-18 in the peritoneal fluid of women with endometriosis

OBJECTIVE

Peritoneal fluid (PF) inflammatory factors may participate in the pathogenesis of endometriosis. The aim of this study was to investigate PF interleukin (IL)-18 levels in women with and without endometriosis.

DESIGN

Controlled clinical study.

SETTING

Women undergoing laparoscopy at a university hospital.

PATIENT(S)

Fifty women with previously untreated endometriosis, 8 women on GnRH agonists for endometriosis, and 18 control women with normal pelvic anatomy who were undergoing tubal ligation.

INTERVENTION(S)

Peritoneal fluid IL-18 levels as measured by ELISA.

MAIN OUTCOME MEASURE(S)

Peritoneal fluid IL-18 levels.

RESULT(S)

Peritoneal fluid IL-18 levels were significantly higher in women with previously untreated endometriosis (mean +/- SEM, 91.1 +/- 6.5 pg/mL) than in control women (59.4 +/- 2.0 pg/mL). Interestingly, women with superficial (100.0 +/- 10.2 pg/mL) and deep peritoneal implants (94.0 +/- 10.8 pg/mL) had significantly higher PF IL-18 levels than did women with endometriomas (57.8 +/- 1.8 pg/mL). Similarly, women with stage I-II endometriosis (97.3 +/- 8.0 pg/mL), but not women with stage III-IV endometriosis (74.9 +/- 9.9 pg/mL), had significantly higher PF IL-18 levels than did control women. Peritoneal fluid IL-18 levels were significantly higher in the luteal phase than in the follicular phase but did not discriminate between women with pelvic pain or infertility.

CONCLUSION(S)

Peritoneal fluid IL-18 is elevated in women with peritoneal, minimal- to mild-stage endometriosis.

Endometriosis and ovarian cancer: thoughts on shared pathophysiology

BACKGROUND

Endometriosis appears to predispose to ovarian cancer. How this may occur has been little discussed.

STUDY DESIGN

This article reviews the English language literature for in vitro, animal, clinical, and epidemiologic studies linking the two conditions.

RESULTS

Pathology case series consistently report endometrioid and clear cell types of ovarian cancer arising from endometriotic foci. Epidemiologic studies have been consistent with this association. There are also marked similarities between the proposed etiology of ovarian cancer and the observed pathophysiology of endometriosis. Specifically, both are characterized by immune alterations. Both conditions are promoted by estrogen excess and by progesterone deficit. Finally, steroid hormones interacting with the immune system may stimulate both endometriosis and ovarian cancer. I propose that the biology common to endometriosis and ovarian cancer represents not just a parallelism, but instead a causal pathway: aberrant immune function, fed by and feeding on estrogens, unbalanced by progesterone, may create a positive feed-forward loop that enhances the growth and invasiveness of endometriosis and promotes its malignant transformation.

CONCLUSIONS

The same pathophysiology may orchestrate the progression of endometriosis and its transformation to endometroid and clear cell ovarian neoplasias. This notion of a unifying biology suggests a directed approach to future research and identifies possible chemoprevention strategies for women with endometriosis.

Immunology and Endometriosis

PROBLEM

Accumulating data suggests that aberrant immune responses during retrograde menstruation may be involved in the development of endometriosis.

METHOD OF STUDY

The role of immunology in the etiology of endometriosis is reviewed and summarized from the available literature.

RESULTS

Immunologic factors may affect a woman's susceptibility to implantation of exfoliated endometrial cells. Immune alterations include increased number and activation of peritoneal macrophages, decreased T cell reactivity and natural killer cell cytotoxicity, increased circulating antibodies, and changes in the cytokine network.

CONCLUSION

There is substantial evidence that immunologic factors play a role in the pathogenesis of endometriosis and endometriosis-associated infertility. Decreased natural killer cell cytotoxicity leads to an increased likelihood of implantation of endometriotic tissue. In addition, macrophages and a complex network of locally produced cytokines modulate the growth and inflammatory behavior of ectopic endometrial implants.

Medical management of endometriosis-associated pain

In the coming years, basic science research into the mechanisms of endometriosis development and persistence almost certainly will open new avenues for treatment. A wide armamentarium of medical therapies already exists, however. The efficacy of most of these methods in reducing endometriosis-associated pain is well established. The choice of which to use depends largely on patient preference after an appropriate discussion of risks, side effects, and cost. Typically, oral contraceptives and NSAIDs are first-line therapy because of their low cost and mild side effects (Box 6). Because of its greater potential for suppressing endometrial development, consideration should be given to prescribing a low-dose monophasic oral contraceptive continuously. If adequate relief is not obtained or if side effects prove intolerable, consideration should be given to the use of progestins (oral, intramuscular, or IUD) or a GnRH agonist with immediate add-back therapy. Progestins are less expensive, but GnRH agonists with add-back may be better tolerated. If none of these medications proves beneficial or if side effects are too pronounced, then repeat surgery is warranted. The surgery may have analgesic value and serves to reconfirm the diagnosis. Finally, if endometriosis is identified at the time of surgery, then consideration should be given to prescribing medical therapy postoperatively.

Adolescent endometriosis

PURPOSE OF REVIEW

Endometriosis can exist in the adolescent female. It can be a very disruptive disease and cause significant dysfunction at a time in life when self-esteem, school attendance, and school performance are critical to achievement of life goals. Approaches to diagnosis and management in the recent literature are reviewed, focusing on those that apply directly to the adolescent or indirectly, by extrapolation from work done in the adult population. Practical strategies for adolescent patient care are presented.

RECENT FINDINGS

Recent research has focused on the efficacy of current treatment modalities and management of potential adverse side effects. Possible etiologies of endometriosis have been proposed, and therapies directed at those causes are being explored. Methods of diagnosis, both invasive and noninvasive, have been studied in order to determine the most effective way of diagnosing the disease.

SUMMARY

A better understanding of the etiology of endometriosis would probably assist in determining the most suitable treatment strategies. Future work in adolescent endometriosis should focus on developing safe, minimally invasive, yet definitive options for diagnosis and treatment.

Endometriosis: novel etiopathogenetic concepts and clinical perspectives

OBJECTIVE

To discuss current ideas about therapy for endometriosis derived from new observations generated by using molecular biology techniques and in vivo animal models of disease.

METHOD(S)

The MEDLINE database was reviewed for English-language articles on new drugs that affect the endocrine or immunologic system, the possibility that endometriosis has multiple forms, and the association of endometriosis with cancer. Specific attention was given to in vivo studies in animals or humans.

CONCLUSION(S)

Among the novel potential candidate drugs, aromatase inhibitors and raloxifene should be considered for treatment of postmenopausal women with endometriosis. Notable observations have emerged from studies of immunomodulators and antiinflammatory agents in animal models of disease. These findings must be confirmed in women. The histogenesis of ovarian endometriomas is still unclear, thus limiting new experimental approaches to this form of disease. Given the low but established risk for malignant transformation of endometriosis, efforts should be directed toward identification of susceptibility loci for the disease and its potential transformation into cancer.

Treating endometriosis as an autoimmune disease

OBJECTIVE

To review the literature on the role of autoimmunity in the etiology of endometriosis, compare the similarities in the pathophysiologies between endometriosis and autoimmune diseases, and discuss the use of immunomodulators currently used to treat autoimmune diseases as potential therapies for endometriosis.

DESIGN

The literature on endometriosis and other autoimmune diseases was reviewed, and summary data are presented.

RESULTS

Endometriosis shares many similarities with autoimmune diseases such as rheumatoid arthritis, Crohn's disease, and psoriasis. These similarities include elevated levels of cytokines, decreased cell apoptosis, and T- and B-cell abnormalities. Because the use of immunomodulators and inflammatory modulators has proven to be an effective means of medical management for these autoimmune diseases, similar therapies may prove useful in treating endometriosis.

CONCLUSION(S)

Although substantial evidence indicates that endometriosis at least shares many similarities with autoimmune diseases, endometriosis is primarily treated by using compounds that induce a hypoestrogenic environment. A review of the literature combined with the shortcomings of current means of medical management for endometriosis support the postulate that treatment of endometriosis with immunomodulators and inflammatory modulators is warranted.

Immunobiology of endometriosis

OBJECTIVE

To provide a review of the humoral and cellular immunology of endometriosis and to discuss the rationale for future approaches to diagnosis and treatment.

DESIGN

Literature survey.

RESULT(S)

Defective immunosurveillance in women who are destined to develop endometriosis may allow for the survival of ectopic endometrial tissue. The evidence includes endometrial cell resistance to apoptosis, perhaps through the secretion of proteins that interfere with implant recognition and/or FasL expression by stromal cells, inducing apoptosis of Fas-bearing immune cells. Although the immune response may be defective, aspects of it clearly are enhanced in endometriosis, as is seen by the generalized polyclonal B-cell autoimmune activation and secretion of immune proteins. Several cytokines, chemokines, and growth factors (including vascular growth factors) are increased in women with endometriosis.

CONCLUSION(S)

A complex network of locally produced cytokines modulate the growth and inflammatory behavior of ectopic endometrial implants. Proinflammatory proteins from endometriotic lesions and associated immune cells contribute to the enhanced inflammatory reaction associated with endometriosis that subserves the survival of these lesions instead of leading to their demise.

Intraperitoneal and subcutaneous treatment of experimental endometriosis with recombinant human interferon-alpha-2b in a murine model

OBJECTIVE

To determine the effect of human interferon (IFN)-alpha-2b on experimental endometriosis in rats.

DESIGN

Experimental, controlled, double-blind randomized study.

SETTING

Experimental surgery laboratory in a university department.

ANIMAL(S)

Ninety-six Wistar rats with endometriosis, induced by transplanting four endometrial fragments into the peritoneal cavity.

INTERVENTION(S)

One third of the animals served as controls (group A). The others were randomly divided into two groups and were given IFN-alpha-2b either as a single intraperitoneal dose (group B) or as three SC doses (on alternate days) (group C).

MAIN OUTCOME MEASURE(S)

Laparotomy was performed to measure the size of each implant at various times (days 0, 6, 12, 20, and 120 after treatment).

RESULT(S)

There were no differences among the groups in the size of the average implants before IFN was administered (17.3+/-6.7, 19.7+/-7.8, and 18.1+/-9.2 mm for groups A, B, and C, respectively). These values were significantly smaller after treatment in group B (14.9+/-8.0 mm) and group C (14.0+/-9.5 mm) than in the control group (17.6+/-7.5 mm) (P<.05). Intraperitoneal IFN produced an initial maximum decrease in the size of the implants (40% reduction on day 6), which diminished until day 20 (20%) and then was maintained on a plateau until day 120 (25%). By contrast, group C showed an initial minimal reduction (13% at day 6), which increased up to day 20 (19%), after which a plateau was reached (23% at day 120). Thus, the effects in both treatment groups were similar in the long term.

CONCLUSION(S)

Two short regimens of human IFN-alpha-2b reduced the size of experimental endometriosis in rats.

Effects of gonadotropin-releasing hormone agonist (GnRHa) and ovariectomy on leukocyte subpopulations in rats with autotransplanted endometrium

PROBLEM

To determine the effect of estrogen deficiency on populations of immune cells in rats with autotransplanted endometrium.

METHOD OF STUDY

Autologous endometrial segments were implanted in the peritoneum of rats. Leukocyte subsets in the peripheral blood (PB) and peritoneal fluid (PF) of autotransplanted rats treated with gonadotropin-releasing hormone agonist (GnRHa) or ovariectomy were analyzed by flow cytometry.

RESULTS

Endometrial growth was suppressed in association with increases in natural killer (NK) cells and macrophages in rats treated surgically or medically after endometrial implantation compared with autotransplanted-only rats. Normal rats treated with GnRHa showed no significant alterations in PB and PF leukocyte subsets, even in NK cells and macrophages, compared with untreated normal rats.

CONCLUSIONS

Data suggest that GnRHa itself did not have an immunomodulating effect when rats were treated for 3 weeks, but that a hypoestrogenic state reduced the size of the ectopic endometrium in association with increases in NK cells and macrophages. Our findings support the hypothesis that ectopic endometrial cells may release immunosuppressive factors.