Monocyte-mediated enhancement of endometrial cell proliferation in women with endometriosis

The Sphingosine 1-Phosphate Axis: an Emerging Therapeutic Opportunity for Endometriosis

Endometriosis is a common condition in women of reproductive age, but its current interventions are unsatisfactory. Recent research discovered a dysregulation of the sphingosine 1-phosphate (S1P) signaling pathway in endometriosis and showed a positive outcome by targeting it. The S1P axis participates in a series of fundamental pathophysiological processes. This narrative review is trying to expound the reported and putative (due to limited reports in this area for now) interactions between the S1P axis and endometriosis in those pathophysiological processes, to provide some perspectives for future research. In short, S1P signaling pathway is highly activated in the endometriotic lesion. The S1P concentration has a surge in the endometriotic cyst fluid and the peritoneal fluid, with the downstream dysregulation of its receptors. The S1P axis plays an essential role in the migration and activation of the immune cells, fibrosis, angiogenesis, pain-related hyperalgesia, and innervation. S1P receptor (S1PR) modulators showed an impressive therapeutic effect by targeting the different S1P receptors in the endometriosis model, and many other conditions resemble endometriosis. And several of them already got approval for clinical application in many diseases, which means a drug repurposing direction and a rapid clinical translation for endometriosis treatments.

Deep immunophenotyping reveals endometriosis is marked by dysregulation of the mononuclear phagocytic system in endometrium and peripheral blood

BACKGROUND

Endometriosis is a chronic, estrogen-dependent disorder where inflammation contributes to disease-associated symptoms of pelvic pain and infertility. Immune dysfunction includes insufficient immune lesion clearance, a pro-inflammatory endometrial environment, and systemic inflammation. Comprehensive understanding of endometriosis immune pathophysiology in different hormonal milieu and disease severity has been hampered by limited direct characterization of immune populations in endometrium, blood, and lesions. Simultaneous deep phenotyping at single-cell resolution of complex tissues has transformed our understanding of the immune system and its role in many diseases. Herein, we report mass cytometry and high dimensional analyses to study immune cell phenotypes, abundance, activation states, and functions in endometrium and blood of women with and without endometriosis in different cycle phases and disease stages.

METHODS

A case-control study was designed. Endometrial biopsies and blood (n = 60 total) were obtained from women with (n = 20, n = 17, respectively) and without (n = 14, n = 9) endometriosis in the proliferative and secretory cycle phases of the menstrual cycle. Two mass cytometry panels were designed: one broad panel and one specific for mononuclear phagocytic cells (MPC), and all samples were multiplexed to characterize both endometrium and blood immune composition at unprecedented resolution. We combined supervised and unsupervised analyses to finely define the immune cell subsets with an emphasis on MPC. Then, association between cell types, protein expression, disease status, and cycle phase were performed.

RESULTS

The broad panel highlighted a significant modification of MPC in endometriosis; thus, they were studied in detail with an MPC-focused panel. Endometrial CD91+ macrophages overexpressed SIRPα (phagocytosis inhibitor) and CD64 (associated with inflammation) in endometriosis, and they were more abundant in mild versus severe disease. In blood, classical and intermediate monocytes were less abundant in endometriosis, whereas plasmacytoid dendritic cells and non-classical monocytes were more abundant. Non-classical monocytes were higher in severe versus mild disease.

CONCLUSIONS

A greater inflammatory phenotype and decreased phagocytic capacity of endometrial macrophages in endometriosis are consistent with defective clearance of endometrial cells shed during menses and in tissue homeostasis, with implications in endometriosis pathogenesis and pathophysiology. Different proportions of monocytes and plasmacytoid dendritic cells in blood from endometriosis suggest systemically aberrant functionality of the myeloid system opening new venues for the study of biomarkers and therapies for endometriosis.

Therapeutic effects of green tea on endometriosis

Endometriosis is a chronic disorder characterized by the presence of endometrial glands and stroma outside the uterine cavity. It affects 8%-10% of women in their reproductive years, and represents a major clinical problem with deleterious social, sexual and reproductive consequences. Current treatment options include pain relief, hormonal intervention and surgical removal. However, these treatments are deemed unsatisfactory owing to varying success, significant side effects and high recurrence rates. Green tea and its major bioactive component, (-)-epigallocatechin gallate (EGCG), possess diverse biological properties, particularly anti-angiogenic, anti-proliferation, anti-metastasis, and apoptosis induction. In recent years, preclinical studies have proposed the use of green tea to inhibit the growth of endometriosis. Herein, the aim of this review is to summarize the potential therapeutic effects of green tea on molecular and cellular mechanism through inflammation, oxidative stress, invasion and adhesion, apoptosis and angiogenesis in endometriosis.

Peripheral, Central, and Cross Sensitization in Endometriosis-Associated Pain and Comorbid Pain Syndromes

Endometriosis-associated pain and the mechanisms responsible for its initiation and persistence are complex and difficult to treat. Endometriosis-associated pain is experienced as dysmenorrhea, cyclical pain related to organ function including dysuria, dyschezia and dyspareunia, and persistent pelvic pain. Pain symptomatology correlates poorly with the extent of macroscopic disease. In addition to the local effects of disease, endometriosis-associated pain develops as a product of peripheral sensitization, central sensitization and cross sensitization. Endometriosis-associated pain is further contributed to by comorbid pain conditions, such as bladder pain syndrome, irritable bowel syndrome, abdomino-pelvic myalgia and vulvodynia. This article will review endometriosis-associated pain, its mechanisms, and its comorbid pain syndromes with a view to aiding the clinician in navigating the literature and terminology of pain and pain syndromes. Limitations of our current understanding of endometriosis-associated pain will be acknowledged. Where possible, commonalities in pain mechanisms between endometriosis-associated pain and comorbid pain syndromes will be highlighted.

The Inflammatory Feed-Forward Loop Triggered by the Complement Component C3 as a Potential Target in Endometriosis

The complement system is a major component of humoral innate immunity, acting as a first line of defense against microbes via opsonization and lysis of pathogens. However, novel roles of the complement system in inflammatory and immunological processes, including in cancer, are emerging. Endometriosis (EM), a benign disease characterized by ectopic endometrial implants, shows certain unique features of cancer, such as the capacity to invade surrounding tissues, and in severe cases, metastatic properties. A defective immune surveillance against autologous tissue deposited in the peritoneal cavity allows immune escape for endometriotic lesions. There is evidence that the glandular epithelial cells found in endometriotic implants produce and secrete the complement component C3. Here, we show, using immunofluorescence and RT-qPCR, the presence of locally synthesized C3 in the ectopic endometriotic tissue, but not in the eutopic tissue. We generated a murine model of EM via injection of minced uterine tissue from a donor mouse into the peritoneum of recipient mice. The wild type mice showed greater amount of cyst formation in the peritoneum compared to C3 knock-out mice. Peritoneal washings from the wild type mice with EM showed more degranulated mast cells compared to C3 knock-out mice, consistent with higher C3a levels in the peritoneal fluid of EM patients. We provide evidence that C3a participates in an auto-amplifying loop leading to mast cell infiltration and activation, which is pathogenic in EM. Thus, C3 can be considered a marker of EM and its local synthesis can promote the engraftment of the endometriotic cysts.

Tofacitinib alters STAT3 signaling and leads to endometriosis lesion regression

Endometriosis is a widespread gynecologic condition affecting up to 15% of women of reproductive age. The Janus kinase/signal transducer and activator of transcription (JAK/STAT3) pathway is upregulated in endometriosis and is a therapeutic target. Here we sought to determine the effect of Tofacitinib, a JAK inhibitor in widespread clinical use, on JAK/STAT signaling in endometriosis and lesion growth. Endometriosis was surgically induced in C57BL/6 mice using homologous uterine horn transplantation. Lesions were allowed to form over 4 weeks followed by Tofacitinib (10 mg/kg) or vehicle administered by oral gavage over 4 weeks. Tofacitinib treatment in vivo led to endometriosis lesion regression and reduced adhesion burden compared to vehicle treatment. In vitro studies on Ishikawa cells showed that Tofacitinib reduced hypoxia-inducible factor 1α and vascular endothelial growth factor mRNA levels at 12 and 24 h. Western blot analysis showed that Tofacitinib effectively reduced STAT3 phosphorylation in Ishikawa cells and human primary stromal and epithelial cells from eutopic endometrium of patients with and without endometriosis. This study suggests that the inhibition of JAK/STAT signaling using Tofacitinib may be a viable method for the treatment of endometriosis.

Endometriosis is a chronic systemic disease: clinical challenges and novel innovations

Endometriosis is a common disease affecting 5-10% of women of reproductive age globally. However, despite its prevalence, diagnosis is typically delayed by years, misdiagnosis is common, and delivery of effective therapy is prolonged. Identification and prompt treatment of endometriosis are essential and facilitated by accurate clinical diagnosis. Endometriosis is classically defined as a chronic, gynaecological disease characterised by endometrial-like tissue present outside of the uterus and is thought to arise by retrograde menstruation. However, this description is outdated and no longer reflects the true scope and manifestations of the disease. The clinical presentation is varied, the presence of pelvic lesions is heterogeneous, and the manifestations of the disease outside of the female reproductive tract remain poorly understood. Endometriosis is now considered a systemic disease rather than a disease predominantly affecting the pelvis. Endometriosis affects metabolism in liver and adipose tissue, leads to systemic inflammation, and alters gene expression in the brain that causes pain sensitisation and mood disorders. The full effect of the disease is not fully recognised and goes far beyond the pelvis. Recognition of the full scope of the disease will facilitate clinical diagnosis and allow for more comprehensive treatment than currently available. Progestins and low-dose oral contraceptives are unsuccessful in a third of symptomatic women globally, probably as a result of progesterone resistance. Oral gonadotropin-releasing hormone (GnRH) antagonists constitute an effective and tolerable therapeutic alternative when first-line medications do not work. The development of GnRH antagonists has resulted in oral drugs that have fewer side-effects than other therapies and has allowed for rapid movement between treatments to optimise and personalise endometriosis care. In this Review, we discuss the latest understanding of endometriosis as a systemic disease with multiple manifestations outside the parameters of classic gynaecological disease.

Immunological Basis of the Endometriosis: The Complement System as a Potential Therapeutic Target

Endometriosis (EM) is a chronic disease characterized by the presence and proliferation of functional endometrial glands and stroma outside the uterine cavity. Ovaries and pelvic peritoneum are the most common locations for endometrial ectopic tissue, followed by deep infiltrating EM sites. The cyclic and recurrent bleeding, the progressive fibrosis and the peritoneal adhesions of ectopic endometrial glands, may cause different symptoms depending on the origin involved. EM is a frequent clinical condition affecting around 10% of women of mainly reproductive age, as well as in post-menopausal women and adolescents, especially with uterine anomalies. The risk of developing EM depends on a complex interaction between genetic, immunological, hormonal, and environmental factors. It is largely considered to arise due to a dysfunction of immunological surveillance. In fact, women with EM exhibit altered functions of peritoneal macrophages, lymphocytes and natural killer cells, as well as levels of inflammatory mediators and growth factors in the peritoneal fluid. In EM patients, peritoneal macrophages are preponderant and highly active compared to healthy women. Peritoneal macrophages are able to regulate the events that determine the production of cytokines, prostaglandins, growth factors and complement components. Several studies have shown alteration in the regulation of the complement activation, leading to chronic inflammation characteristic of EM. Aberrant regulation/activation of the complement system has been observed in the peritoneal cavity of women affected by EM. Thus, complement inhibition may represent a new approach for the treatment of EM, given that a number of complement inhibitors are under pre-clinical and clinical development. Such an intervention may provide a broader therapeutic control of complement-mediated inflammatory damage in EM patients. This review will focus on our current understanding of the role of complement activation in EM and possible modalities available for complement-based therapy.

The endometrial immune environment of women with endometriosis

BACKGROUND

Endometriosis, a common oestrogen-dependent inflammatory disorder in women of reproductive age, is characterized by endometrial-like tissue outside its normal location in the uterus, which causes pelvic scarring, pain and infertility. While its pathogenesis is poorly understood, the immune system (systemically and locally in endometrium, pelvic endometriotic lesions and peritoneal fluid) is believed to play a central role in its aetiology, pathophysiology and associated morbidities of pain, infertility and poor pregnancy outcomes. However, immune cell populations within the endometrium of women with the disease have had incomplete phenotyping, thereby limiting insight into their roles in this disorder.

OBJECTIVE AND RATIONALE

The objective herein was to determine reproducible and consistent findings regarding specific immune cell populations and their abundance, steroid hormone responsiveness, functionality, activation states, and markers, locally and systemically in women with and without endometriosis.

SEARCH METHODS

A comprehensive English language PubMed, Medline and Google Scholar search was conducted with key search terms that included endometriosis, inflammation, human eutopic/ectopic endometrium, immune cells, immune population, immune system, macrophages, dendritic cells (DC), natural killer cells, mast cells, eosinophils, neutrophils, B cells and T cells.

OUTCOMES

In women with endometriosis compared to those without endometriosis, some endometrial immune cells display similar cycle-phase variation, whereas macrophages (Mø), immature DC and regulatory T cells behave differently. A pro-inflammatory Mø1 phenotype versus anti-inflammatory Mø2 phenotype predominates and natural killer cells display abnormal activity in endometrium of women with the disease. Conflicting data largely derive from small studies, variably defined hormonal milieu and different experimental approaches and technologies.

WIDER IMPLICATIONS

Phenotyping immune cell subtypes is essential to determine the role of the endometrial immune niche in pregnancy and endometrial homeostasis normally and in women with poor reproductive history and can facilitate development of innovative diagnostics and therapeutics for associated symptoms and compromised reproductive outcomes.

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.

Blood soluble interleukin 1 receptor accessory protein levels are consistently low throughout the menstrual cycle of women with endometriosis

BACKGROUND

A deficiency in the counter-regulatory mechanisms of interleukin 1 (IL1) may play a significant role in endometriosis pathogenesis and associated chronic inflammation. The aim of this study was to investigate peripheral blood levels of soluble IL1 receptor accessory protein (sIL1RAP), a potent natural inhibitor of IL1, in women with and without endometriosis.

METHODS

Peripheral blood samples were collected from women with endometriosis (n = 47) consulting for infertility, pelvic pain or tubal ligation, in whom the disease was diagnosed at laparoscopy. Control healthy women (n = 27) were requesting tubal ligation or reanastomosis and had no visible evidence of endometriosis at laparoscopy. sIL1RAP levels were determined by ELISA, whereas estradiol (E2) and progesterone (P4) levels were determined by competitive immunoassays.

RESULTS

sIL1RAP levels were significantly decreased in women with early endometriosis stages compared to controls (p < 0.05) and markedly during the proliferative phase of the menstrual cycle (p < 0.001). Actually, while sIL1RAP were significantly increased in the proliferative compared to the secretory phase in normal women (p < 0.0001) and peaked at the end of this phase, sIL1RAP remained consistently low and showed non-significant variations throughout the menstrual cycle in women with endometriosis.

CONCLUSIONS

Lower circulating levels of sIL1RAP points to a significant impairment in the counter-regulatory mechanisms of IL1, which in view of the cytokine's potent inflammatory and growth-promoting properties may play a significant role in the pathophysiology of endometriosis.

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

BACKGROUND

The effect of rosiglitazone, an activator of peroxisome proliferator-activated receptor-gamma, on the growth of ectopic uterine tissue was assessed.

METHODS

Endometriosis was surgically induced in 28 rats by transplanting an autologous fragment of endometrial tissue onto the inner surface of the abdominal wall. Four weeks later, rats were randomly grouped and a second laparatomy was performed. The length, width, height and volume of the explants were measured. Rosiglitazone at 0.2 mg/kg/day was orally administered to one group, while vehicle treatment was given to the control group. Four weeks later, rats were sacrificed and ectopic uterine tissues were re-evaluated morphologically and histologically. Scoring system was used to evaluate the preservation of epithelia.

RESULTS

One rat in the study group and two rats in the control group died as a result of complications related to surgery. There was a significant difference in post-treatment length, width, height, and spherical volumes between control and rosiglitazone-treated groups. The epithelia were found to be preserved significantly better in the control group when compared with the rosiglitazone-treated group.

CONCLUSION

Rosiglitazone was found to cause regression of experimental endometriosis in rats.

Is Endometriosis Associated with Systemic Subclinical Inflammation?

Endometriosis is a pelvic inflammatory process with altered function of immune-related cells and increased number of activated macrophages in the peritoneal environment that secrete various local products, such as growth factors and cytokines. The elevation of cytokines and other factors in the peritoneal fluid is accompanied by the elevation of similar factors, such as CRP, SAA, TNF-alpha, MCP-1, IL-6, IL-8 and CCR1, in the peripheral blood of patients with endometriosis. CD44+ and CD14+ monocytes are significantly increased, while CD3+ T lymphocytes and CD20+ B lymphocytes show modest, but significant decrease in peripheral blood of women with endometriosis. This indicates that endometriosis could be viewed as a local disease with systemic subclinical manifestations. This review provides an overview of data on the changes of various factors in peripheral blood and their potential use as diagnostic tools in patients with endometriosis.

Endometriosis as a model for inflammation–hormone interactions in ovarian and breast cancers

Chronic inflammation has been implicated in a variety of cancers. In this review, we consider associations between endometriosis and cancers both local (ovarian) and distant (breast). We review the epidemiological data linking endometriosis to ovarian and breast cancers. We then consider evidence for a role for sex steroid hormones and for inflammation in the aetiology of each of these cancers. Finally, we consider that endometriosis may promote alterations in sex steroid hormones and inflammatory mediators. A possible explanation for the association between endometriosis and these reproductive cancers may then be local and systemic enhancement of aberrant inflammatory and hormonal mediators. If this hypothesis is true, endometriosis may need to be considered as a risk factor for ovarian and breast cancers, triggering increasingly intensive surveillance. Moreover, treatments for endometriosis may require consideration of the impact on long-term cancer risk.

Increased Interleukin-6 Messenger RNA Expression in Macrophage-Cocultured Endometrial Stromal Cells in Adenomyosis

PROBLEM

To determine the effects of macrophage on endometrial stromal cells (ESCs) in women with adenomyosis.

METHOD OF STUDY

Eutopic endometrium was obtained and separated into single ESC in 10 women with adenomyosis (study group) and 11 without adenomyosis (control group). ESCs were then cultured alone or with macrophage for 24 hr.

RESULTS

Immunohistochemistry identified the presence of interleukin-6 (IL-6), IL-8, and IL-10 in ESCs. Real-time quantitative PCR revealed that the IL-6 mRNA was significantly expressed in macrophage-cocultured ESCs in adenomyosis than that in the controls, but was not different in ESCs cultured alone between the two groups. The levels of IL-8 and IL-10 mRNA were similar in ESCs either cultured alone or with macrophage between women with and without adenomyosis.

CONCLUSION

IL-6 mRNA was significantly expressed in ESCs after in vitro coculture with macrophage in adenomyosis. This aberrant behavior of ESCs might play a role in the formation of ectopic endometrial implants in adenomyosis.

Experimental Intestinal Endometriosis Is Characterized by Increased Levels of Soluble TNFRSF1B and Downregulation of Tnfrsf1a and Tnfrsf1b Gene Expression1

Endometriosis is commonly associated with symptoms similar to those of gastrointestinal diseases, such as inflammatory bowel disease (IBD), leading to erroneous diagnosis and inappropriate management. The role of tumor necrosis factor alpha (TNF) in IBD is well established, but its role in endometriosis--also characterized by the activation of inflammatory mechanisms--is still under study. Furthermore, little is known about the involvement of TNF receptors. Intestinal endometriosis was surgically induced in female Sprague-Dawley rats (n = 10). Control rats (n = 10) received sutures with no implants. Samples of tissue and fluids were collected 60 days after surgery. Endometriotic implants were classified in grades, and the gastrointestinal tract was examined for damage. A significant increase was observed in protein levels of TNF and soluble TNFRSF1B in the peritoneal fluid of experimental rats compared to controls. Expression of Tnf mRNA was significantly increased both in peritoneal leukocytes and in intestinal segments associated with implants in experimental animals. Bioactivity of TNF in tissues was confirmed by overexpression of Icam1, Sele, Vegfa, Flt1 and Kdr. Gene expression of Tnfrsf1a and Tnfrsf1b was downregulated in colon and small intestine of experimental animals, possibly as a mechanism of protection against TNF cytotoxicity. Significant overexpression of genes encoding TNF receptor-associated factors that have been linked to activation of antiapoptotic pathways also was observed. Overexpression of TNF and target genes, underexpression of TNF-receptor genes, and increased shedding of TNFRSF1B in this animal model provide further evidence for involvement of the TNF system in the pathogenesis of endometriosis.

IL-10-dependent down-regulation of MHC class II expression level on monocytes by peritoneal fluid from endometriosis patients

Endometriosis is a gynecologic disorder characterized by the ectopic growth of misplaced endometrial cells. Moreover, immunological abnormalities of cell-mediated and humoral immunity may be associated with the pathogenesis of endometriosis. The effects of peritoneal fluid (PF) from endometriosis patients on the expression levels of MHC class II and costimulatory molecules on the cell surfaces of monocytes were investigated. Compared to the PF of controls, the addition of 10% PF (n=10) from patients with endometriosis to culture medium significantly reduced the percentage of MHC class II-positive cells in cultures of a THP-1, monocytic cell line at 48 h. The effect of endometriosis patient PF (EPF) was dose-dependent, and similar effect was observed in peripheral blood monocytes. An inverse correlation was found between MHC class II expression level and IL-10 concentration in EPF (r=-0.518; p=0.019) and in the supernatant of peripheral blood monocyte cultured in EPF (r=-0.459; p=0.042) (n=20). The expression levels of costimulatory molecules (CD80 and CD86), but not of CD54 and B7-H1, were down-regulated by EPF. The mRNA level of HLA-DR was unaffected by EPF but protein level was reduced by EPF. Neutralizing IL-10 antibody abrogated MHC class II down-regulation on monocytes, which had been induced by EPF. However, in a functional assay, monocytes treated with EPF failed to stimulate T cell in mixed leukocyte reaction, although T cell proliferation was increased with EPF-treated monocytes and Staphylococcus enterotoxin B. These results suggest that MHC class II expression level on monocytes is down-regulated by EPF, but the cell stimulatory ability of monocytes does not coincide with MHC class II expression level.

Elevated levels of macrophage migration inhibitory factor in the peripheral blood of women with endometriosis

OBJECTIVE

To evaluate the concentrations of macrophage migration inhibitory factor (MIF) in the peripheral blood of normal women and patients with endometriosis.

DESIGN

Retrospective study using ELISA to measure peripheral blood MIF.

SETTING

Gynecology clinic and human reproduction research laboratory.

PATIENT(S)

Thirty-eight normal women and 55 women with endometriosis.

INTERVENTION(S)

Peripheral blood samples were obtained a few days before laparoscopy.

MAIN OUTCOME MEASURE(S)

The MIF concentrations in blood serum.

RESULT(S)

This current study showed a 364% increase in MIF concentrations in women with endometriosis as compared to normal women. A significant increase was seen in endometriosis stages I-II, but a more marked increase was observed in the more advanced stages of the disease (III-IV). Both fertile and infertile women with endometriosis had higher levels of MIF than normal controls, but the difference was more significant in infertile women with endometriosis. Women with endometriosis with no pelvic pain had higher levels of MIF than normal controls, but a more significant increase in MIF levels was observed in women with endometriosis reporting pelvic pain.

CONCLUSION(S)

This study showed a marked increase in MIF concentrations in the peripheral blood of women with endometriosis and a relationship with disease progress, and suggests that MIF may be involved in endometriosis-related pain and infertility.

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.

Blood leukocyte subsets are modulated in patients with endometriosis

OBJECTIVE

To determine whether blood leukocyte populations could be modulated in endometriosis.

DESIGN

Case-control study.

SETTING

Eight clinical institutions of the Montreal area.

PATIENT(S)

Women with regular menstrual cycles who underwent laparoscopy or laparotomy between 1997 and 2001 and who were not under hormonal treatment for at least 3 months were selected. This study includes 175 cases and 131 controls.

MAIN OUTCOME MEASURE(S)

The proportion of blood leukocytes expressing markers for T, B lymphocytes, monocytes, or natural killer (NK) cells were compared by flow cytometric analysis between cases and controls.

RESULT(S)

Age and parity were identified as important confounders. Given that smoking, history of acute infection, and previous use of oral contraceptives strongly correlate with the level of some blood leukocyte populations, these parameters were taken into account in addition with age and parity when the level of blood leukocyte subsets were evaluated in cases and controls. Blood monocytes expressing CD14 and CD44 molecules were increased in patients with endometriosis. Alternatively, B lymphocytes were shown to be significantly decreased in cases compared with controls.

CONCLUSION(S)

Although these results suggest that endometriosis is associated with some systemic manifestations, the exact role of these modulations remains unclear.

Pathogenesis of endometriosis

Endometriosis is a common gynecologic disorder characterized by the presence of endometrial tissue outside the uterine cavity. Various theories have been put forth to explain the mechanisms for the development of this disease. Although no single theory can explain all cases of endometriosis, the retrograde menstruation theory has gained the widest acceptance. This theory proposes that viable endometrial tissue is refluxed through the fallopian tubes during menstruation and implants on peritoneal surface or pelvic organs. Retrograde menstruation occurs in 76% to 90% of women. The much lower prevalence of endometriosis suggests that additional factors determine susceptibility to endometriosis. Once in the peritoneal cavity, the survival and implantation of endometrial cells seem to be mediated by abnormal MMP and TIMP expression, altered immune milieu, aberrant local aromatase activity, and genetic and environmental factors.

Relationship between apoptosis and the number of macrophages in eutopic endometrium from women with and without endometriosis

OBJECTIVE

To investigate the relationship between apoptotic cells and macrophages in the eutopic endometrium of women with and without endometriosis.

DESIGN

Retrospective analysis of archival uterine endometrial biopsy specimens.

SETTING

Institute for the Study and Treatment of Endometriosis, and university-based pathology and research laboratories.

PATIENT(S)

Fifty-one women with endometriosis and 24 healthy control subjects without endometriosis.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The number of TUNEL+ (terminal deoxynucleotide transferase [TdT]-mediated deoxyuridine triphospate [dUTP] nick end-labeling-positive) (apoptotic) cells and CD68+ (CD68 positive) (macrophages).

RESULT(S)

Apoptotic cells and macrophage numbers were positively correlated in the eutopic endometrium of women with and without endometriosis. However, the number of apoptotic cells and the macrophage content in the endometrium of women with endometriosis was significantly reduced compared with that of healthy control subjects without endometriosis. Differences between apoptosis and macrophage numbers between the two populations were observed predominantly during the early proliferative phase of the menstrual cycle.

CONCLUSION(S)

The reduction in apoptosis described for endometrial cells in women with endometriosis may be related to reduced macrophage trafficking into the eutopic endomtrium during the early-proliferative phase of the menstrual cycle.

Peritoneal fluid-mediated enhancement of eutopic and ectopic endometrial cell proliferation is dependent on tumor necrosis factor-alpha in women with endometriosis

OBJECTIVE

To determine the effect of autologous peritoneal fluid and tumor necrosis factor-alpha (TNF-alpha) on proliferation of endometrial cells from women with endometriosis.

DESIGN

Endometrial cells from eutopic and ectopic endometrium were cultured in vitro with peritoneal fluids or recombinant TNF-alpha for 72 hours before DNa synthesis determination by 3H-thymidine labeling and liquid scintillation counting.

SETTING

An institute for the study and treatment of endometriosis and university-based research laboratories.

PATIENT(S)

Thirty-five women with endometriosis and 17 controls without endometriosis.

MAIN OUTCOME MEASURE(S)

In vitro incorporation of 3H-thymidine in endometrial cells was examined.

RESULT(S)

Peritoneal fluid from women with endometriosis enhanced proliferation of autologous and heterologous endometrial cell cultures from women with endometriosis. The soluble TNF-receptor etanercept blocked the ability of peritoneal fluid from women with endometriosis to enhance proliferation of eutopic or ectopic endometrial cells. Recombinant TNF-alpha also enhanced proliferation of eutopic and ectopic endometrial cells from women with endometriosis. In contrast, autologous peritoneal fluid, heterologous peritoneal fluid from women with endometriosis, and recombinant TNF-alpha failed to enhance, and often inhibited, the proliferation of eutopic endometrial cells from controls without endometriosis.

CONCLUSION(S)

Endometrial cells from women with endometriosis can utilize factors in peritoneal fluids, such as TNF-alpha, to facilitate proliferation in ectopic environments. Endometrial cells from women without endometriosis do not share this ability, suggesting that this abnormality is etiologically related to development of the disease. Therapy with agents that block the effects of TNF-alpha may be warranted.

Soluble interleukin-1 receptor type II blocks monocyte chemotactic protein-1 secretion by U937 cells in response to peripheral blood serum of women with endometriosis

OBJECTIVE

To assess the ability of peripheral blood serum from women with endometriosis to induce monocyte chemotactic protein-1 (MCP-1) secretion by monocytes and the putative role of the interleukin-1 (IL-1) system in endometriosis-associated monocyte activation.

DESIGN

Cultures of U937 monocytic cells exposed to serum from normal women (control group) or women with endometriosis.

SETTING

Gynecology clinic and human reproduction research laboratory.

PATIENT(S)

Seventy-nine women with endometriosis and 38 control women with no evidence of endometriosis at laparoscopy.

INTERVENTION(S)

Peripheral blood obtained a few days before laparoscopy.

MAIN OUTCOME MEASURE(S)

MCP-1 secretion in the culture medium and serum concentrations of soluble IL-1 receptor type II (sIL-1RII), IL-1beta, and IL-1alpha by ELISA or by enzyme immunometric assay.

RESULT(S)

Serum concentrations of sIL-1RII were significantly lower in women with stage I-II endometriosis than in control women, whereas serum concentrations of IL-1beta and IL-1alpha were comparable between the two groups. The serum of women with endometriosis induced higher secretion of MCP-1 by U937 cells than that of control women, particularly in the initial stages of endometriosis (stages I-II), and recombinant IL-1RII (rIL-1RII) significantly blocked that secretion.

CONCLUSION(S)

These findings point toward a deficiency in the mechanisms involved in the down-regulation of IL-1 actions at the systemic level and reveal sIL-1RII as a key factor involved in that process.

Macrophages, oxidation, and endometriosis

Retrograde menstruation has been suggested to be the cause for the presence of endometrial cells in the peritoneal cavity. However, little is known about the events that lead to the adhesion and growth of these cells that ultimately result in endometriosis, considering the fact that the disease occurs only in certain women despite the common occurrence of retrograde menstruation in most women. We postulate that, in normal women, the endometrial cells and tissue that arrive in the peritoneal cavity during menstruation are effectively removed by macrophages that are chemoattracted and become resident tissue macrophages in the peritoneal cavity. In contrast, the peritoneal macrophages in women with endometriosis are nonadherent and ineffectively scavenged, resulting in the sustained presence and growth of the endometrial cells. We also postulate that the peritoneal fluid is not a passive reservoir of the factors secreted by cells of the peritoneum, but actively promotes endometriosis. The peritoneal fluid is rich in lipoproteins, particularly low-density lipoprotein, which generates oxidized lipid components in a macrophage-rich inflammatory milieu. The oxidants exacerbate the growth of endometriosis by inducing chemoattractants such as MCP-1 and endometrial cell growth-promoting activity. We provide evidence for the presence of oxidative milieu in the peritoneal cavity of women with endometriosis, the nonscavenging properties of macrophages that are nonadherent, and the synergistic interaction between macrophages, oxidative stress, and the endometrial cells. For example, the peritoneal fluid lipoproteins of subjects with endometriosis have increased the propensity to undergo oxidation as compared with plasma lipoproteins, and the subjects also have increased titer of autoantibodies to oxidatively modified proteins. If the oxidative proinflammatory nature of the peritoneal fluid is an important mediator of endometriosis growth, anti-inflammatory agents and antioxidants might afford protection against endometriosis.

Regulation and modulation of abnormal immune responses in endometriosis

There is ample evidence demonstrating that endometriosis is accompanied by inflammatory reactions in the peritoneum, resulting in abnormal levels of a variety of cytokines and chemokines in the peritoneal fluid. Among the immunological parameters that have been shown to be altered in the peritoneal cavity of women with endometriosis, an increase in the number of activated nonadherent macrophages that show reduced surface expression of scavenger receptors has been observed. The cause-and-effect relationship between aberrant peritoneal macrophage activity and endometriosis is still unknown. We have demonstrated that steroid hormone receptor agonists and antagonists [e.g., retinoids, antiglucocorticoids, ligands to peroxisome proliferator activated receptors (PPARs)] can regulate macrophage functions in ways that could either suppress or stimulate the growth of ectopic endometrial lesions. Our studies include a number of relevant findings: (1) RU486, acting as an antioxidant, can suppress activation of NFkappaB, a nuclear transcription factor that affects the expression of several inflammatory genes such as those for MCP-1, GM-CSF, CSF-1, and various adhesion molecules; (2) IL-6 secretion from a variety of cell types including endometrial cells is inhibited by retinoic acid; and (3) retinoids and PPARgamma ligands can upregulate the expression of scavenger receptors in cells of the monocyte/macrophage lineage. These observations, combined with the possibility that macrophage activity may play a fundamental role in endometriosis, suggest that pharmacologic manipulation of macrophage function may provide a novel mechanism for treating this disease.

Modulation of neutrophil apoptosis by plasma and peritoneal fluid from patients with advanced endometriosis

BACKGROUND

The increased production of pro-inflammatory chemoattractant cytokines for neutrophils in endometriosis suggests that changes in the immune system play an important role in the pathophysiology of endometriosis. The effects of plasma and peritoneal fluid from patients with advanced endometriosis on the apoptosis of neutrophils were investigated.

METHODS

Apoptotic changes of neutrophils were evaluated by morphological changes using Giemsa staining. Apoptosis was confirmed by DNA electrophoretic analysis.

RESULTS

Compared with the plasma (n = 20) and peritoneal fluid (n = 5) of healthy controls, the addition of 10% plasma (n = 20) and peritoneal fluid (n = 10) from patients with endometriosis to an in-vitro culture of neutrophils from healthy subjects reduced the percentage of apoptotic cells from 65.3 +/- 6.6 to 27.2 +/- 4.6% (P < 0.001) and from 45.3 +/- 4.8 to 10.5 +/- 4.3% (P < 0.001) respectively. Neutralizing interleukin-8 antibody abrogated the delay of neutrophil apoptosis induced by peritoneal fluid, but not in the plasma of endometriosis patients.

CONCLUSIONS

These findings show that interleukin-8 is one of the neutrophil survival factors in the peritoneal fluid of endometriosis patients and that an unidentified survival factor is also present in the plasma of patients with endometriosis.

New considerations for the pathogenesis of endometriosis

OBJECTIVES

To review the available evidence regarding the immunological, epidemiological and other factors involved in the pathogenesis of endometriosis.

METHODS

Literature review.

RESULTS

Endometriosis remains a poorly-understood disease of unknown etiology and pathogenesis.

CONCLUSIONS

There is evidence to suggest that alterations in the immune response, whether genetically transmitted or environmentally induced, predispose women to the ectopic implantation of endometrial cells transported into the peritoneal cavity by way of retrograde menstruation. This predisposition may exist because of an impaired peritoneal clearing of endometrial cells and fragments or because of pathological angiogenesis.

Apoptosis in endometrial glandular and stromal cells in women with and without endometriosis

BACKGROUND

The aetiology of endometriosis is unknown. Ectopic dissemination of the endometrial cells gives origin to endometriotic lesions, but occurs in women with and without endometriosis. It has been suggested that increased ectopic cell survival facilitates their implantation. The objectives of this study were to evaluate endometrial apoptosis in women with endometriosis according to: (i) cyclic changes, (ii) glandular and stromal contribution, and (iii) stage of the disease.

METHODS

The subjects were women undergoing diagnostic laparoscopy and endometrial biopsies for suspected endometriosis. Spontaneous apoptosis was evaluated using TdT-mediated dUTP-biotin nick end-labelling (TUNEL) assay. Apoptotic cells per 10 mm(2) (apoptotic index) in an area of 10-50 mm(2) in 5 microm endometrial tissue sections were counted and location of these cells was recorded.

RESULTS

The apoptotic index in glandular epithelium was lower in endometriosis than controls (26.0 +/- 5.5 versus 51.2 +/- 9.7, P = 0.03) but not in the stroma (36.3 +/- 6.4 versus 48.4 +/- 11.3, NS). In controls, apoptosis was highest during the late secretory/menstrual and early proliferative phases and cyclic variability was apparent. In endometriosis, this cyclic variability was lost. There was a trend toward decreased apoptosis with increasing stage of the disease, but the differences lacked statistical significance.

CONCLUSIONS

Spontaneous apoptosis is decreased in the endometrial glands in women with endometriosis, especially during late secretory/menstrual and early proliferative phases of the cycle. This may indicate increased viability of endometrial cells shed during menses, facilitating their ectopic survival and implantation.

Theories of endometriosis

Endometriosis is characterised by the presence of abnormally located tissue resembling the endometrium with glands and stroma. Several hypotheses have attempted to explain the development of such tissue. The oldest theory, that of metaplasia, suggests that under diverse influences coelomic tissue could be transformed into endometrium. The most often cited theory, that of implantation, proposes that the physiological phenomenon of endometrial reflux in the fallopian tubes during menstruation may, in certain conditions, overcome local defense mechanisms, implant, and proliferate. The peritoneal fluid in unaffected women possesses the capacity to prevent endometriotic tissue from becoming established. The reasons for the occurrence of endometriosis and its consequences (pain, sterility, adhesions) are probably numerous and involve the endometrium, the immune system (macrophages, natural killer cells), the peritoneum, and fallopian tubes. The failure to clear the peritoneal cavity of fragments of endometrium could cause a state of local inflammation with hyperactivation of macrophages secreting a variety of different compounds. Some of these compounds may bring about metaplasia of the peritoneum or the development of Mullerian residues.

Is endometriosis an endometrial disease?

Endometriosis is characterised by the presence of abnormally located tissue resembling the endometrium with glands and stroma. Several hypotheses have attempted to explain the development of such tissue. The most often cited theory, that of implantation, proposes that the physiological phenomenon of endometrial reflux in the fallopian tubes during menstruation may, in certain conditions, overcome local defense mechanisms, implant, and proliferate. The implantation theory does not explain why endometriosis will develop only in approximately 10-15% of women, while the reflux of endometrial tissue via the fallopian tubes during menstruation is a quasi-universal phenomenon. The endometrium of women affected by endometriosis could be abnormal compared with endometrium of healthy women. The abnormal endometrium could be able to protect itself from harmful effects of immune cells by expressing specific antigens, by harbouring a different immune cell population and by synthetizing and secreting immunosuppressive factors. Several others characteristic features of endometrium have been described in women with endometriosis: (1) production of its own estrogens in too heavy amount; (2) aptitude for setting up on peritoneum; (3) tendencies to proliferate and to invade tissue; (4) aggressiveness for the peritoneum; (5) auto-protection from physiological apoptosis; (6) abnormal expression of heat shock proteins; and (7) excessive angiogenesis.

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Endometriosis is one of the most frequent gynecological disorders in the reproductive age. Discrepancies between clinical findings and subjective Symptoms cause the question of the determing factors for the subjective experience. In the present study an hermeneutic, sense-orientated approach was employed by using qualitative methods of research. Eleven interviews with endometriosis patients were recorded on tape and transcribed, followed by an individual-case and a comparative analysis in partly deductively and inductively defined categories. The psychosexual development has been found as negatively influenced. Endometriosis patients show conflicting concepts of their sex-specific role. A found aggression conflict manifests itself in the pain Sensation, at an intrapsychic land an interpersonnel level: it influences the relations with other persons, in particular, the doctor-patient relationship. Changes of sense in the doctor-patient-relationship and recent concepts of psychosomatic disorders are discussed.

Effects of peritoneal macrophages from women with endometriosis on endometrial cellular proliferation in an in vitro coculture model

OBJECTIVE

To study the effects of peritoneal macrophages on endometrial cellular proliferation in an in vitro coculture model and to compare the magnitude of these effects between macrophages from women with endometriosis and normal women.

DESIGN

Controlled study of peritoneal macrophage function.

SETTING

University hospital.

PATIENT(S)

Patients with a normal peritoneal cavity (n = 15) and with pelvic endometriosis (n = 20) undergoing laparoscopy.

INTERVENTION(S)

Peritoneal macrophages were cocultured with endometrial epithelial and stromal cells; endometrial cell cultures without macrophage coculture acted as controls.

MAIN OUTCOME MEASURE(S)

Endometrial cellular proliferation measured by 3H-thymidine incorporation.

RESULT(S)

Endometrial epithelial cells cocultured with peritoneal macrophages from women with endometriosis showed significantly increased proliferation compared with cocultures using macrophages from normal women when assessed at 24 hours (1.56 versus 1.03 times, respectively, over control) and at 72 hours (1.55 versus 1.10 times over control). Endometrial stromal cells cocultured with peritoneal macrophages from women with endometriosis similarly exhibited increased proliferation compared with cocultures using macrophages from normal women when assessed at 24 hours (1.65 versus 1.17 times over control) and at 72 hours (1.65 versus 1.21 times over control).

CONCLUSION(S)

Peritoneal macrophages of patients with endometriosis stimulate cellular proliferation of endometrial epithelial and stromal cells in vitro.

Cytolysis of eutopic and ectopic endometrial cells by peripheral blood monocytes and peritoneal macrophages in women with endometriosis

OBJECTIVE

To compare the ability of peripheral blood monocytes (PBM) and peritoneal macrophages (PM) to mediate the in vitro cytolysis of endometrial cells from eutopic and ectopic endometrium in women with endometriosis.

DESIGN

Prospective study of immune function.

SETTING

Institute for the Study and Treatment of Endometriosis and university-based research laboratories.

PATIENT(S)

Twenty-four women with endometriosis (15 in stage I/II, 9 in stage III/IV) and 4 patients treated with GnRH agonists.

INTERVENTION(S)

Peritoneal fluid and peripheral blood were sampled and eutopic and ectopic endometrium were biopsied during diagnostic laparoscopy.

MAIN OUTCOME MEASURE(S)

Lysis of autologous endometrial cells.

RESULT(S)

Peripheral blood monocytes were significantly more cytolytic than peritoneal macrophages against autologous uterine endometrial cells. However, PBM and PM displayed a similar degree of cytolysis against a hepatoma cell line. Ectopic endometrial cells were significantly more resistant to cytolysis by autologous PBMC than were matched eutopic endometrial cells, and were completely resistant to cytolysis by autologous PM.

CONCLUSION(S)

The reduced capacity of PM from women with endometriosis to mediate the destruction of endometrial cells coupled with the increased resistance of ectopic endometrial cells to macrophage-mediated cytolysis may facilitate the survival of these cells within the peritoneal cavity of women with endometriosis.

Peritoneal fluid levels of immunoreactive corticotropin-releasing factor (CRF) and CRF-binding protein (CRF-BP) in healthy and endometriosic women

Corticotropin-releasing factor (CRF) is a 41-amino acid neurohormone involved in the neuroendocrine response to stress, also playing a role in cell-mediated immune functions and in inflammation. In the light of recent evidence showing an association between endometriosis and altered cellular immunity factors, the present study investigates immunoreactive (ir) CRF in the peritoneal fluid of healthy women, and in patients with pelvic adhesions and endometriosis. In addition, peritoneal fluid concentrations of CRF-binding protein (CRF-BP), a 37-kDA protein of 322 amino acids able to modulate central and peripheral CRF functions, were evaluated. Peritoneal fluid samples (n = 35) were collected from healthy women (n = 12), from patients with intrapelvic adhesions (n = 8), and from women with endometriosis (n = 15). In the control group a specimen of blood was collected. Peritoneal fluid and plasma CRF levels were measured by a two-site immunoradiometric assay (IRMA), and CRF-BP levels were measured by a specific radioimmunoassay (RIA). CRF and CRF-BP levels in peritoneal fluid were lower than plasma values, and independent of the phase of the menstrual cycle: in particular, in healthy women there was no significant difference between peritoneal fluid and plasma CRF-BP levels during two phases of the menstrual cycle. Peritoneal fluid levels of CRF and CRF-BP were similar in healthy patients and women with pelvic adhesions or with endometriosis, and when patients with adhesions or with endometriosis were considered as single group, no difference in CRF and CRF-BP levels was noted in comparison to the control group. In patients with endometriosis, no significant differences in peritoneal fluid CRF or CRF-BP levels were recorded, although in patients with stage 2 and stage 3 of the disease peritoneal fluid CRF-BP levels were higher than in healthy patients or in those with a lower grade of the disease. These results suggest that the peritoneal concentration of these hormones may reflect the circulating levels: the absence of any significative variations in peritoneal fluid CRF levels according to the degree of the endometriosis, suggests a limited role of CRF in the immunological changes related to the disease

Pathogenesis of endometriosis

This article reviews the pathogenesis of endometriosis, which involves retrograde dissemination of endometrium and/or development in situ by metaplasia, and there is evidence suggesting that genetic and hormonal factors may play a role. There is also substantial evidence that immunologic factors, namely peritoneal macrophages, T cells, natural killer cells, and soluble products secreted by these cells, are involved in the pathogenesis of endometriosis.

Monocyte chemotactic protein-1 concentration in peritoneal fluid of women with endometriosis and its modulation of expression in mesothelial cells

OBJECTIVE

To investigate monocyte chemotactic protein-1 concentrations in the peritoneal fluid (PF) of women with or without endometriosis, then assess peritoneal mesothelial cells as a potential source of monocyte chemotactic protein-1.

DESIGN

Prospective study.

SETTING

University medical center.

PATIENT(S)

Women with (n = 60) or without (n = 18) endometriosis.

INTERVENTION(S)

First monocyte chemotactic protein-1 levels in PF were measured, then mesothelial cells in culture were treated with cytokines.

MAIN OUTCOME MEASURE(S)

In PF and culture supernatants, monocyte chemotactic protein-1 was measured by ELISA. In vitro monocyte chemotactic protein-1 messenger RNA expression was evaluated by Northern analysis.

RESULT(S)

The median concentration of monocyte chemotactic protein-1 in PF of control women was 137 pg/mL (conversion factor to SI unit, 0.115; range, 12 to 418 pg/mL); that of women with moderate endometriosis was 205 pg/mL (range 65 to 6,000 pg/mL); and that of those with severe endometriosis was 1,165 pg/mL (0 to 2,602 pg/mL). Within the moderate to severe endometriosis group, monocyte chemotactic protein-1 levels were higher in women with untreated endometriosis (354 pg/mL range 0 to 6,000 pg/mL) than in women receiving GnRH agonist (128 pg/mL, range 0 to 216 pg/mL). In the control group, monocyte chemotactic protein-1 levels were higher in the proliferative phase than in the secretory phase. Mesothelial cells produced constitutively monocyte chemotactic protein-1; moreover, both interleukin-1 alpha and tumor necrosis factor-alpha induced higher levels of monocyte chemotactic protein-1.

CONCLUSION(S)

Levels of monocyte chemotactic protein-1 in PF were higher during the proliferative phase than secretory phase of control women and increased in moderate to severe endometriosis. The regulated expression of monocyte chemotactic protein-1 may recruit macrophages into PF and contribute to the pathogenesis of endometriosis.

Continuous exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin inhibits the growth of surgically induced endometriosis in the ovariectomized mouse treated with high dose estradiol

The objectives of this study were to evaluate the effects of repeated injection of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the growth of endometriosis and the formation of adhesions in the mouse. Sexually mature female B6C3F1 mice (n = 19) were ovariectomized and subcutaneously implanted with a silastic capsule containing estradiol (E2). Uterine tissues in full thickness (I x I mm2, 5 pieces) from the left uterine horn were surgically autotransplanted to 5 different locations in the peritoneal cavity. One week later the animals were randomly assigned to four groups and treated with: vehicle alone (corn oil). 10.50 or 100 ng/kg/day TCDD for 28 days. Two days after last dose a necropsy was performed to measure the diameter of endometrial implants and to score the adhesions. Endometrial implants were harvested for histology and blood was collected for assessment of E2 levels. The diameter of endometrial implants was significantly smaller in the TCDD treated groups compared to the controls (p < 0.05). Survival of endometrial implants, the formation and scores of adhesions, and serum E2 levels were not significantly different among the dosing groups. Histology of implants showed a significant regression of endometrial tissues in the animals receiving 50 and 100 ng/kg/day TCDD compared to the controls. We conclude that continuous exposure to TCDD resulted in regression of the endometriotic implants in the ovariectomized mice treated with a high dose exogenous F2.

Increased monocyte chemotactic protein-1 level and activity in the peripheral blood of women with endometriosis. Le Groupe d'Investigation en Gynécologie

OBJECTIVE

Our purpose was to evaluate monocyte chemotactic protein-1 in the peripheral blood of women with and without endometriosis.

STUDY DESIGN

Fifty-seven patients with endometriosis at laparoscopy done for infertility and pelvic pain were compared with 44 fertile women with no evidence of endometriosis at tubal ligation by laparoscopy. Monocyte chemotactic protein-1 concentration in the plasma was determined by enzyme-linked immunosorbent assay and its biologic activity was evaluated by measuring monocyte chemotaxis with use of a human histiocytic cell line (U937).

RESULTS

Monocyte chemotactic protein-1 concentrations (median and range of values) found in the plasma were higher in patients with endometriosis (163, 0 to 788 pg/ml) than in normal controls (0, 0 to 355 pg/ml). This elevation was significant only in the minimal stage of endometriosis (revised American Fertility Society stage I). However, increased chemotactic activity (mean number of migrating cells/mm2 +/- SEM) was found in the stages I (1240 +/- 141), II (519 +/- 30), and III-IV (523 +/- 23) of the disease compared with normal controls (205 +/- 20). A total of 35% to 44% of this activity was inhibited in the presence of an antibody specific to monocyte chemotactic protein-1.

CONCLUSION

Endometriosis is associated with increased level and activity of monocyte chemotactic protein-1 in the peripheral blood. The elevation and activation of this cytokine could play a relevant role in the immunoinflammatory process associated with the disease.

The role of estradiol, progesterone, and transforming growth factor on human endometrioma cell culture

The present study demonstrates several aspects of endometrioma cells in culture, namely, 1) cell growth, proliferation, and morphology, 2) effect of cell culture on estrogen and progesterone receptor concentration, 3) effect of estradiol, progesterone, and transforming growth factor. The tissue sample was obtained from ovarian endometriomas that were removed via laparotomy or laparoscopy. The tissue sample was digested with collagenase. After washing, the tissue was cultured in endothelial cell culture medium. Cell count was done by flow cytometry. Receptor study was done by immunohistochemistry. The results demonstrated the growth and proliferation of endometrioma cell in culture medium. Electron microscopy showed stroma-like cells. The cells lost their estrogen and progesterone receptors. Estradiol and progesterone added to these cultures did not affect the rate of growth and proliferation of the cells. Transforming growth factor significantly increased the rate of growth and proliferation of these cells.

Increased levels of interleukin-6 and interleukin-10 in the peritoneal fluid of patients with endometriosis

OBJECTIVE

The levels of interleukin-2, interleukin-4, interleukin-5, interleukin-6, interleukin-10, and granulocyte-macrophage colony-stimulating factor were measured in the peritoneal fluid of 15 patients with endometriosis to characterize the type of immune response that occurs at the site of endometriosis.

STUDY DESIGN

Cytokine levels in peritoneal fluid obtained during laparoscopy from 15 patients and 12 controls undergoing tubal ligation were determined by enzyme-linked immunosorbent assay.

RESULTS

The mean levels of interleukin-6 in patients with endometriosis and controls were 797 +/- 407 pg/ml and 133 +/- 38 pg/ml, respectively (p < 0.02). Similarly, the mean concentration of interleukin-10 in peritoneal fluids of patients with endometriosis was significantly higher than that of controls (241 +/- 38 vs 128 +/- 21, p < 0.05). The levels of interleukin-2, interleukin-4, interleukin-5, and granulocyte-macrophage colony-stimulating factor were not significantly different between the two study groups.

CONCLUSIONS

The levels of interleukin-6 and interleukin-10 are increased in the peritoneal fluids of patients with endometriosis, suggesting enhanced macrophage activity in these patients. Increased interleukin-6 and interleukin-10 production may partially contribute to the disturbed immune regulation observed in patients with endometriosis.

Differential expression of VLA beta 1 (CD29) on monocytes from patients with endometriosis

PROBLEM

Previous studies have established that in vitro proliferation of endometrial cells is enhanced by peripheral blood monocytes (PBM) and suppressed by peritoneal macrophages (PM) from patients with endometriosis but only suppressed by PBM and PM obtained from normal subjects. The functional activity of PBM and PM is influenced by the engagement of numerous cell surface receptors with their respective physiological ligands.

METHOD

In this study, PBM and PM from fertile women (Group 1), women with unexplained infertility (Group 2), and women with limited (Group 3) or severe (Group 4) endometriosis were isolated in order to analyze these cells for the expression of CD54, CD58 and HLA-DR (immunoglobulin supergene antigens) CD18 and CD29 (integrins) and CD44 (an addresin). These cell surface antigens are involved in monocyte/macrophage trafficking, activation, signal transduction and/or adhesion.

RESULTS

No differences were detected in the percentage of PBM expressing CD18, CD44, CD54, CD58, or HLA-DR among the four groups of subjects. Furthermore, the density of these antigens expressed on PBM was identical in patients and control subjects. In contrast, the percentage of PBM expressing CD29 (also known as VLA beta 1) and the density of CD29 expressed per cell were significantly reduced (P < 0.01) in patients with limited endometriosis compared to controls and patients with severe disease. Interestingly, although the percentage of CD29+ PBM from women with severe endometriosis was not statistically different from the percentage of CD29+ PBM from controls, the density of CD29 expressed per cell was significantly elevated among patients with severe disease. Analysis of PM from the four subject groups revealed no differences in CD29 expression or density. However, the percentage of PM expressing CD18 was significantly decreased in patients with limited (but not severe) endometriosis.

CONCLUSION

Since both CD18 and CD29 play a role in cell trafficking and/or adhesion, alterations in their expression among patients with endometriosis suggest that these integrin beta chains may play a role in the pathogenesis of the disease.

Immunological aspects of endometriosis

During the past decade, evidence has accumulated indicating an association between endometriosis and changes in humoral and cell-mediated immunity. However, it is not clear whether immune changes are the sequelae or play a role in the etiopathogenesis of the disease. The latter concept is supported by the observation that exposure of rhesus monkeys to radiation or immunotoxicants leads several years later to an increase in frequency and severity of endometriosis. Studies from our laboratories support the theory that endometrial cells misplaced during menses can implant in ectopic locations only in women with genetically or environmentally altered cell-mediated immune function. Development of endometriosis may then prompt a humoral response in some women, which results in the production of autoantibodies to endometrial cells or cell-derived antigens. These autoantibodies may cross-react with the uterine endometrium, interfere with implantation, and cause infertility or early spontaneous abortions. We recently observed that the presence of autoantibodies in endometriosis was associated with significantly lower in vitro fertilization/embryo transfer pregnancy rates. Interestingly, in about 30% of women with unexplained infertility, immune changes characteristic of endometriosis were also present, suggesting a subclinical form of this disease. We conclude that: (1) women with unexplained infertility should have studies of the immune function to rule out subclinical form of endometriosis; (2) evaluation of infertility in women with endometriosis should include an assessment of autoantibody status; and (3) treatment methods involving autoantibody suppression should be considered in women with endometriosis positive for autoantibodies.

Cell proliferation is increased in the endometrium of women with endometriosis

OBJECTIVE

To compare the proliferation of endothelial, epithelial, and stromal cells in the endometrium of women with endometriosis and normal controls.

DESIGN

Proliferating cells were identified using the monoclonal antibody antiproliferating cell nuclear antigen. A second antibody (CD34) was used to identify endothelial cells (ECs).

SETTING

University Department of Obstetrics and Gynaecology.

PATIENTS

Women with laparoscopically proven endometriosis, n = 30. Controls were women with a normal pelvis at laparoscopy performed for tubal sterilization or for infertility due to a male factor, n = 27.

MAIN OUTCOME MEASURES

Endothelial cells: proliferative index. Epithelial and stromal cells: semi-quantitative immunostaining score.

RESULTS

The mean EC proliferative index was significantly greater in those with endometriosis compared with controls. This difference was most marked during the proliferative phase of the menstrual cycle. Proliferative phase epithelial and stromal cells demonstrated significantly higher immunostaining scores in endometriosis patients than in controls.

CONCLUSIONS

We have demonstrated increased numbers of proliferating ECs as well as epithelial and stromal cells in proliferative phase endometrium of women with endometriosis. This suggests that the endometrium of these women might have an enhanced ability to implant and survive in ectopic locations.