Altered immune environment in peritoneal endometriotic lesions: relationship to lesion appearance.

OBJECTIVE: To study the localization of and quantify different immune cell populations in red, black, and white peritoneal endometriotic lesions and compare immune cell densities between lesions and the surrounding tissue. DESIGN: Cross-sectional study. SETTING: Teaching hospital, university research laboratory. PATIENT(S): Participants undergoing laparoscopic excision of endometriosis were recruited from gynecological operating theaters at Royal Prince Alfred Hospital, Sydney (n = 28). INTERVENTION(S): Immunohistochemical staining for and quantification of dendritic cells (mature and immature), T cells (effector, cytotoxic, and regulatory), B cells, and macrophages in endometriotic peritoneal lesions and the surrounding tissue. MAIN OUTCOME MEASURE(S): Immune cell densities and aggregates were quantified. RESULT(S): Red and black lesions are significantly more likely to be surrounded by immune cell aggregates than white lesions (P=.036). In the tissue surrounding the peritoneal endometriotic lesions, there was a consistent pattern of greater and more variable density of immune cell populations for red lesions than black or white lesions and a range of significant positive correlations between densities of different immune populations (all P≤.004; not observed within the lesion stroma). CONCLUSION(S): There is a greater presence of immune cells in the tissue surrounding earlier/red and black lesions than older scarred white lesions, particularly in the form of immune cell aggregates, indicating an immunologic response in close proximity to the adjacent lesion. The relationship between densities of immune populations in the tissue surrounding the lesions suggests complementary recruitment and local interactions between cells. Categorizing immune cell populations in proximity to peritoneal endometriotic lesions may improve the understanding of lesion persistence and transition to older white appearances. Early (red) peritoneal endometriotic lesions are surrounded by a greater density of immune cells, including immune aggregates, than later (black or white) lesions. These immune cells may support lesion persistence.

The Lymphatic System in Endometriosis: a Pilot Study of Endometrial-Like Cells and Immune Cell Populations in Lymph Nodes Associated with Deep Infiltrating Bowel Lesions.

In endometriosis, the lymphatic and immune systems are implicated in disease establishment and progression. The objective of this pilot study was to examine endometrial-like, and for the first time, immune cell populations in lymph nodes associated with deep infiltrating endometriosis (DIE) bowel lesions. Premenopausal women undergoing excision of endometriosis and/or hysterectomy were included. DIE bowel lesion-associated (n = 10) and other pelvic (n = 15) lymph nodes were studied. Samples were immunohistochemically stained for endometrial-like cells (CD10), T cells (CD3, CD4, CD8, and FoxP3), dendritic cells (DC; DC-Lamp and DC-Sign), B cells (CD20, CD79 and plasma), macrophages (CD68), and natural killer cells (NK; CD57). Cell abundance (percentage positive area) and antigen expression (optical density; OD) were quantified. Endometrial-like cells and each immune cell population were present in all studied nodes. The DIE bowel lesion-associated nodes showed features of immune activation, with T cell proliferation (CD3+ area p = 0.007, CD4+ area p = 0.015 compared with other pelvic nodes); and a mixture of helper and regulatory T cells, B cells, DCs, macrophages, and plasma cells present in the paracortex. In DIE bowel lesion-associated compared with other pelvic nodes, CD10+ endometrial-like cells were reduced (percentage positive area p < 0.001, OD p = 0.004). This study provides new insight into lymphatic and immune system involvement in advanced endometriosis. In particular, we have shown evidence of immune activation in DIE lesion-associated nodes. This was despite lower endometrial-like cell numbers compared with other pelvic nodes. The observations contribute to a developing understanding of the local immune response to advanced disease.

Endometrial polyps: Pathogenesis, sequelae and treatment.

Endometrial polyps are overgrowths of endometrial glands that typically protrude into the uterine cavity. Endometrial polyps are benign in nature and affect both reproductive age and postmenopausal women. Although endometrial polyps are relatively common and may be accompanied by abnormally heavy bleeding at menstruation. In asymptomatic women, endometrial polyps may regress spontaneously, in symptomatic women endometrial polyps can be treated safely and efficiently with hysteroscopic excision.

The Expression and Cellular Localisation of Neurotrophin and Neural Guidance Molecules in Peritoneal Ectopic Lesions.

Endometriosis is a gynaecological disorder characterised by the presence of endometrial-like tissue outside the uterus. It affects 10-15% of women during their reproductive age. The existence of close and complex relationship between chronic pelvic pain and endometriosis are widely recognised. However, the mechanisms of pain generation in women with endometriosis remain poorly understood. Immunohistochemistry was used to assess the density of nerve fibres stained with protein gene product 9.5 (PGP9.5) and the expression of various neurotrophins including glial cell derived neurotrophic factor (GDNF), persephin, neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4) and neuronal guidance molecules semaphorin 3E and Slit-2 and their receptors Plexin-D1 and Robo4 in peritoneal ectopic lesions from women with endometriosis and uninvolved peritoneum samples. Neurotrophins and neuronal guidance molecules and their receptors are synthesised in situ within peritoneal ectopic lesion which suggest their role in facilitating and maintaining the growth of nerve fibres. These molecules were found to be overall most highly expressed in the glands of endometriotic peritoneal lesions. In addition, the presence of ectopic lesions within the peritoneal cavity may affect the environment; in turn, the peritoneum altered appeared to play a role in the growth of nerve fibres and their development and maintenance in peritoneal lesions. Through exploring different neuronally active factors in and around ectopic lesions which may be contributing to pain generation, this study provides an insight and better understanding of the pain mechanisms associated with peritoneal endometriosis.

Blood microvasculature and lymphatic densities in endometrial polyps and adjacent and distant endometrium.

OBJECTIVE: Endometrial polyps are localised growths of endometrial tissue containing glands, stroma and blood vessels, covered with epithelium. The reported prevalence of endometrial polyps is dependent upon the population being studied and the uterine imaging technique utilised. The light microscopy literature provides very little information regarding their microvasculature and lymphatic systems; however, a plethora of ultrasound data demonstrating single central arteries in most medium- or large-sized endometrial polyps are well documented. METHODS: Archived formalin-fixed paraffin-embedded blocks of endometrial curettings were retrieved from files for women with confirmed endometrial polyps (n = 20) and women with normal endometrium (control endometrium; n = 32). Immunohistochemistry was performed with the antibodies CD31 (blood vessels) and D2-40 (lymphatics). Blood vessels and lymphatics were quantified in endometrial polyps and adjacent, distant and control endometrium. RESULTS: CD31 and D2-40 staining was present in all specimens, although there were no significant differences in blood vessel (F(3,70) = 2.36, p = 0.079) and lymphatic (F(3,70) = 0.16, p = 0.920) densities between endometrial polyps as well as adjacent, distant and control endometrium. There were also no significant differences in women with endometrial polyp-associated bleeding and those with no bleeding. In relation to infertility, there were no significant differences found in blood and lymphatic densities between women with endometrial polyps who were infertile and those with endometrial polyps who were fertile. CONCLUSION: Small blood vessel wall and perivascular structures rather than the distribution of vessels may be associated with abnormal bleeding.

Peripheral and endometrial dendritic cell populations during the normal cycle and in the presence of endometriosis.

BACKGROUND: Dysfunctional immune response may be implicated in endometriosis pathogenesis, and dendritic cells (DC) may play greater roles in this response than previously recognized. This study set out to evaluate peripheral blood and endometrial DC population changes in the presence and absence of endometriosis pathology. METHODS: Endometrial (n = 83) and peripheral blood samples (n = 30) were subjected to immunohistochemical techniques and flow cytometry, respectively, to assess DC populations in women with and without endometriosis. Three circulating DC subsets (MDC1, MDC2 and PDC, expressing CD1c, CD303 and CD141), and late-stage mature endometrial DCs (using DC-LAMP antibody) were investigated. RESULTS: A highly significant reduction in CD1c intensity on MDC1 populations in peripheral blood was observed between normal cycle proliferative and menstrual phases (p = 0.025), but not in women with endometriosis, in whom CD1c intensity was markedly increased at the time of menstruation (p = 0.05). A significant reduction in peripheral blood MDC2 (p = 0.016) and apparent reduction in endometrial DC-LAMP+ DC (trend, p = 0.062) were observed in women with endometriosis compared with controls, consistent with our preliminary DC data. CONCLUSIONS: Cyclical variation in endometrial and circulating DC populations appears to be crucial during normal menstrual cycles and in the establishment of pregnancy. In endometriosis, circulating and endometrial DC populations are significantly dysregulated at a number of levels, and are likely to contribute to inefficient immunological targeting of endometrial fragments shed at menstruation, facilitating their survival and establishment of endometriosis.

Angiogenesis, lymphangiogenesis and neurogenesis in endometriosis.

Endometriosis is a common, benign gynecological disease affecting 10 - 15% of reproductively aged women. It is characterized by the presence of endometrial-like tissue at sites outside the uterus. The most widely accepted theory of endometriosis pathogenesis proposes that shed menstrual endometrium can reach the peritoneum, implant and grow as endometriotic lesions. Angiogenesis, lymphangiogenesis and neurogenesis are implicated in successful ectopic establishment and the generation of endometriosis-associated symptoms. This review considers these processes as they occur in the eutopic endometrium and ectopic endometriotic lesions of women with endometriosis. Their regulation is inter-connected and complex. Dysregulation in endometriosis occurs on a background of accumulating evidence that endometriosis is an endometrial disease with underlying genetic influences and cross talk with endometriotic lesions. Understanding the roles of angiogenesis, lymphangiogenesis and neurogenesis in endometriosis pathophysiology is essential for the development of novel therapeutic approaches.

A novel pilot study of endometrial stromal cells and immune cell populations in sentinel uterine-draining lymph nodes during the menstrual cycle and in endometriosis.

Recent studies suggest that changes in certain uterine immune cell populations in endometrium of women with endometriosis are likely to precede changes at ectopic sites. This preliminary study is a first look into the function of uterine-draining lymph nodes (LNs) during the menstrual cycle and in the presence of endometriosis. Paraffin-embedded obturator LNs were obtained from women with (n = 7, mean age 44.3) and without (n = 9, mean age 38.4) endometriosis, who had undergone hysterectomy for cervical or ovarian cancer and in whom LN involvement was not detected. Immunohistochemical staining for endometrial stromal cells and a range of immune cell populations was performed. The CD10+ endometrial stromal cells were detected in uterine-draining LNs throughout the menstrual cycle with numbers peaking during menstruation. The inflammatory process of menstruation was also associated with increased numbers of CD3+, CD4+, Foxp3+, DC-Sign+, CD68+, CD20+, CD79+, and plasma cells. In endometriosis, CD10+ endometrial stromal cells were further increased in numbers, but CD3+, CD4+, DC-Lamp+, FoxP3+, and plasma cells were reduced. This study indicates that efficient immunological responses may be required to contain shed endometrial fragments within the draining uterine LNs thus preventing their further dissemination with establishment of ectopic lesions at distant sites.

Discovery of a novel biomarker in the urine in women with endometriosis.

OBJECTIVE: To investigate whether proteins secreted in urine differ between women with and without endometriosis. DESIGN: Laboratory study using human urine. SETTING: University-based laboratory. PATIENT(S): Women with and without endometriosis undergoing laparoscopy, hysteroscopy and curettage. INTERVENTION(S): Urine collection from women with and without endometriosis. MAIN OUTCOME MEASURE(S): Proteomic techniques and mass spectrometry to identify proteins secreted in the urine of women with and without endometriosis. RESULT(S): On average, 133 proteins were significantly different between women with and without endometriosis. Cytokeratin-19 was highly up-regulated in the urine of women with endometriosis. CONCLUSION(S): Cytokeratin-19 may be a valuable urinary biomarker for endometriosis.

Nerve fibers in ovarian endometriomas.

Ovarian endometriomas (n = 29) were innervated by mainly sympathetic and sensory fibers. These fibers may be involved in the generation of pain symptoms.

The role of Foxp3+ regulatory T-cells in endometriosis: a potential controlling mechanism for a complex, chronic immunological condition.

BACKGROUND: Endometriosis is an inflammatory condition, associated with highly dysregulated immune response at both uterine and peritoneal levels. Surprisingly, Foxp3+ regulatory T-cells, which control and suppress a range of immune responses, have not previously been investigated in endometriosis. METHODS AND RESULTS: Immunohistochemical analysis of Foxp3+ cells in 127 eutopic endometrial samples and 59 ectopic peritoneal lesions revealed that these immune cell populations are highly disturbed in women suffering from endometriosis. We showed that Foxp3+ cells remained highly up-regulated during the secretory phase of the menstrual cycle, while at this time their expression is significantly down-regulated in women without endometriosis (P < 0.001). Foxp3+ cells were detected in the stroma of 18 of the 59 peritoneal endometriotic lesions, but not in the surrounding or control peritoneal tissue. CONCLUSIONS: We propose that in eutopic endometrium in women with endometriosis Foxp3+ cells decrease the ability of newly recruited immune cell populations to effectively recognize and target endometrial antigens shed during menstruation, allowing their survival and ability to implant in ectopic sites. At these ectopic sites, variable expression of Foxp3+ cells within some peritoneal endometriotic lesions is likely to be linked to the characteristics and stage of individual lesion development and be playing key roles in pathogenesis and progression of this unique condition.

Neuroendocrine cells in eutopic endometrium of women with endometriosis.

BACKGROUND: Endometriosis is a common gynaecological disease, but the pathogenesis of endometriosis and pathophysiological basis for endometriosis-associated painful symptoms are still uncertain. Little is known about neuroendocrine (NE) cells in the uterus. METHODS: For this study, 38 premenopausal women with histologically diagnosed ovarian endometrioma or peritoneal endometriosis and 24 women without endometriosis were selected. Biopsy samples from eutopic endometrium were used for immunohistochemical staining to detect synaptophysin (SYN) and neuron-specific enolase (NSE) expression in women with and without endometriosis. RESULTS: There were substantially more NE cells of eutopic endometrium stained with SYN and NSE in women with endometriosis than in those without endometriosis (3.8 +/- 1.8 versus 0.5 +/- 0.7/mm2, P < 0.001, and 2.8 +/- 2.1 versus 0.4 +/- 0.6/mm2, respectively, P < 0.001). These cells were scattered in the epithelium of endometrial glands. At all stages of the menstrual cycle, the densities of NE cells stained with SYN and NSE were greater in women with endometriosis than in those without endometriosis (P < 0.05). CONCLUSIONS: These results suggest that NE cells in eutopic endometrium probably play some role in the pathogenesis or symptoms of endometriosis.

Hyperinnervation in intestinal deep infiltrating endometriosis.

STUDY OBJECTIVE: To investigate the extent and types of innervation of endometriotic lesions in various regions of the bowel. DESIGN: Retrospective nonrandomized immunohistochemical study (Canadian Task Force classification II-3. SETTING: University-based laboratory. PATIENTS: Thirty-six women undergoing laparoscopy or laparotomy because of deep infiltrating endometriosis in various regions of the bowel, including the sigmoid colon, appendix, and rectum. INTERVENTIONS: Immunohistochemical staining of endometriotic specimens with antibodies against protein gene product 9.5, neurofilament, nerve growth factor, nerve growth factor receptors tyrosine kinase receptor A and p75, growth-associated protein 43, substance P, neuropeptide Y, and vasoactive intestinal peptide to demonstrate myelinated, unmyelinated, sensory, and autonomic nerve fibers. MEASUREMENTS AND MAIN RESULTS: There were significantly more nerve fibers in intestinal deep infiltrating endometriosis (mean [SD] 172.6 [94.2]/mm(2)) than in other deep infiltrating endometriotic lesions (e.g., cul-de-sac and uterosacral ligament) (67.6 [65.1]/mm(2); p<.01). Intestinal deep infiltrating endometriosis was innervated abundantly by sensory Adelta,sensory C, cholinergic, and adrenergic nerve fibers. Nerve growth factor, tyrosine kinase receptor A, and p75 were strongly expressed in endometriotic lesions, and growth-associated protein-43 was also strongly expressed in the endometriosis-associated nerve fibers. CONCLUSION: The hyperinnervation in intestinal deep infiltrating endometriosis may help to explain why patients with this type of lesion have more severe pain.

Dendritic cell populations in the eutopic and ectopic endometrium of women with endometriosis.

BACKGROUND: Immune alterations may be involved in the pathogenesis and progression of endometriosis. Dendritic cells (DCs) are potent antigen presenting cells that are highly involved in the initiation of the immune response. The aim of this study was to investigate DC populations in the eutopic and ectopic endometrium of women with endometriosis compared with controls. METHODS: Hysterectomy samples were obtained from premenopausal women with (n = 33) and without (n = 28) endometriosis. In addition, paired peritoneal endometriotic lesions and uterine curettings were collected from 32 women with endometriosis. Specimen sections were stained immunohistochemically using antibodies for monoclonal mouse antibodies directed against human CD1a and CD83, which are specific for immature and mature DCs, respectively. RESULTS: The mean density of endometrial CD1a+ DCs in the basal layer was significantly increased in women with endometriosis compared with controls during the proliferative phase only (P = 0.001). There was a highly significant decrease in the density of endometrial CD83+ DCs in women with endometriosis compared with controls in both layers of the endometrium across all phases of the menstrual cycle (P = 0.001). The density of CD1a+ DCs was significantly increased in peritoneal endometriotic lesions (P = 0.003) and in the surrounding peritoneum (P = 0.001) compared with paired uterine curettings and peritoneum distant from the lesion. CONCLUSIONS: Both CD1a+ and CD83+ DC populations were altered in the eutopic and ectopic endometrium of women with endometriosis compared with controls. Alterations in these cells, which play a crucial role in the coordination of the immune response, may be involved in pain generation and the pathogenesis of endometriosis.

Novel finding of high density of activated mast cells in endometrial polyps.

Endometrial polyps are benign lesions frequently identified in women with infertility or abnormal uterine bleeding in the reproductive and postmenopausal phases We report the striking observation that the numbers of activated mast cells expressing tryptase are increased more than sevenfold throughout the cycle in endometrial polyps (n = 20) compared with normal endometrium. This novel finding has important implications for growth, development, and symptoms associated with polyps in many different tissues.

Rich innervation of deep infiltrating endometriosis.

BACKGROUND: Deep infiltrating endometriosis (DIE) is a specific type of endometriosis, which can be associated with more severe pelvic pain than other forms of endometriotic lesions. However, the mechanisms by which pain is generated are not well understood. METHODS: DIE (n = 31) and peritoneal endometriotic (n = 40) lesions were sectioned and stained immunohistochemically with antibodies against protein gene product 9.5, neurofilament, nerve growth factor (NGF), NGF receptors tyrosine kinase receptor-A (Trk-A) and p75, substance P, calcitonin gene-related peptide, vesicular acetylcholine transporter, neuropeptide Y, vasoactive intestinal peptide and tyrosine hydroxylase to demonstrate myelinated, unmyelinated, sensory and autonomic nerve fibres. RESULTS: There were significantly more nerve fibres in DIE (67.6 +/- 65.1/mm(2)) than in peritoneal endometriotic lesions (16.3 +/- 10.0/mm(2)) (P < 0.01). DIE was innervated abundantly by sensory Adelta, sensory C, cholinergic and adrenergic nerve fibres; NGF, Trk-A and p75 were strongly expressed in endometriotic glands and stroma of DIE. CONCLUSIONS: The rich innervation of DIE may help to explain why patients with this type of lesion have severe pelvic pain.

Macrophages and nerve fibres in peritoneal endometriosis.

BACKGROUND: Endometriosis is considered to be an inflammatory disease, and macrophages are the most numerous immune cells in endometriotic lesions. However, the mechanisms underlying the elevation of macrophages and their role in the pathogenesis and manifestations of endometriosis still remain unclear. METHODS: The number of macrophages stained for CD68 in endometriotic lesions (n = 24) and in peritoneum distant from the lesions (n = 14) from women with endometriosis was compared with the number of macrophages in normal peritoneum from women without endometriosis (n = 18). Peritoneal lesions were also double-stained for CD68 and protein gene product 9.5 to study the relationship between macrophages and nerve fibres. RESULTS: The densities of macrophages in peritoneal endometriotic lesions and unaffected peritoneum from women with endometriosis were both significantly higher than that in normal peritoneum from women without endometriosis (P < 0.001). More nerve fibres were also found in the areas where increased numbers of macrophages were identified. CONCLUSIONS: There was a significant elevation of macrophages in both normal peritoneum and peritoneal lesions from women with endometriosis compared with normal peritoneum from women without endometriosis. These cells may well play roles in the growth and development of endometriotic lesions and in the generation of pain through interaction with nerve fibres.

Abdominal bloating: an under-recognized endometriosis symptom.

OBJECTIVE: To explore the association between the symptom of abdominal bloating and the diagnosis of endometriosis. METHODS: Twenty-six patients with endometriosis diagnosed by laparoscopy and 25 women without endometriosis were recruited to a case-control study. Subjects completed detailed questionnaires regarding perception of abdominal bloating, bloating-related symptoms, and effect on lifestyle. Abdominal girth was measured three times daily for one whole menstrual cycle, as were ratings of perceived abdominal bloating severity and discomfort. Experiences of abdominal and gastrointestinal symptoms were compared. RESULTS: A significantly larger proportion of women with endometriosis than control subjects experienced abdominal bloating (96% vs. 64%). In women with abdominal bloating, the following were more common in those who had endometriosis: associated severe discomfort (30% vs. 0%), wearing loose clothes during bloating (87% vs. 38%), and simultaneous hand swelling (30% vs. 6%). The experiences of cyclically related diarrhea and constipation were more frequent with endometriosis. While there were significant changes in bloating and discomfort ratings across the menstrual cycle, there was a trend towards a difference between the control subjects and unmedicated endometriosis groups only in how the pattern of bloating severity fluctuated across the cycle. Lower abdominal girth measurements changed significantly across menstrual cycle phases. Control and unmedicated endometriosis groups differed significantly in girth changes across the menstrual cycle, controls experiencing much less variation. Compared with the unmedicated endometriosis group, women receiving hormonal treatment had higher bloating severity ratings and discomfort scores, but there was no objective difference in abdominal girth. CONCLUSION: Painful abdominal bloating appears to be common in women with endometriosis and causes considerable symptomatic distress.

Macrophage expression in endometrium of women with and without endometriosis.

BACKGROUND: Endometriosis is an inflammatory condition, characterized by the presence of endometrial-like tissue outside the uterus. The immune system provides a defence mechanism in response to foreign pathogens, and macrophages play important roles in this response. Activation of macrophages has been reported in peritoneal fluid and ectopic endometriotic lesions; however, controversy exists regarding the composition and function of macrophage populations in eutopic endometrium of women with and without endometriosis. This study aimed to quantify macrophages in eutopic endometrium of women with and without endometriosis, during the early, mid and late proliferative and menstrual phases of the cycle. METHODS: Paraffin-embedded endometrial curettage blocks were selected from pathology archives. Seventy-six specimens from women with and without endometriosis were analysed using standard immunohistochemical techniques with CD68-PGM1 (phosphoglucomutase 1) clone antibody. Macrophages were counted according to their morphology over several fields of view. RESULTS: A significant increase in macrophage cell numbers was shown in eutopic endometrium in women with endometriosis (mean +/- SD, 182.7 +/- 72.9/mm(2)) during all stages of the proliferative phase compared with normal controls (101.6 +/- 53.4/mm(2); P < 0.001). Significant increase in macrophage density occurred in the control group during the mid-menstrual phase, Days 3-4 (P < 0.01), which was not observed in women with endometriosis. CONCLUSIONS: This study further supports an association between immune changes in eutopic endometrium and presence of endometriosis. However, it remains uncertain if eutopic immune changes are primary or secondary occurrences.

Effect of progestogens and combined oral contraceptives on nerve fibers in peritoneal endometriosis.

OBJECTIVE: To investigate how progestogens and combined oral contraceptives change nerve fiber density in peritoneal endometriotic lesions and to identify the types of nerve fibers still present during hormone treatment. DESIGN: Laboratory study using human tissue. SETTING: University-based laboratory. PATIENT(S): Hormonally treated and untreated women with endometriosis undergoing laparoscopy, hysteroscopy, and curettage. INTERVENTION(S): Biopsy samples from peritoneal endometriotic lesions in hormonally treated and untreated women with endometriosis. MAIN OUTCOME MEASURE(S): Types and density of nerve fibers were immunohistochemically determined in peritoneal endometriotic lesions from hormonally treated and untreated women with endometriosis. RESULT(S): The nerve fiber density (mean +/- standard deviation/mm(2)) in peritoneal endometriotic lesions from hormone-treated women with endometriosis (10.6 +/- 2.2/mm(2)) was statistically significantly lower than in peritoneal endometriotic lesions from untreated women with endometriosis (16.3 +/-10.0/mm(2)). Nerve growth factor and nerve growth factor receptor p75 expression in peritoneal endometriotic lesions were slightly reduced in hormone-treated women with endometriosis compared with untreated women with endometriosis. CONCLUSION(S): Progestogens and combined oral contraceptives reduced nerve fiber density and nerve growth factor and nerve growth factor receptor p75 expression in peritoneal endometriotic lesions.