Circulating and Endometrial Regulatory T Cell and Related Populations in Endometriosis and Infertility: Endometriosis Is Associated with Blunting of Endometrial Cyclical Effects and Reduced Proportions in Moderate-Severe Disease

Evidence to date supports regulatory T cell (Treg) alterations in endometriosis; however, the relationship remains unclear, and Tregs have not previously been investigated with respect to infertility in endometriosis. This prospective cross-sectional cohort study details circulating and endometrial tissue-specific disturbances in Tregs and broader gated populations in women of reproductive age with and without endometriosis (n = 57 and 29, respectively) using flow cytometry and immunohistochemistry. Participants were characterised by menstrual cycle phase, r-ASRM endometriosis disease stage and fertility status.In the endometrium of women with endometriosis, endometrial Tregs and CD4+ lymphocyte proportions did not change between the proliferative and secretory phases, while in women without the disease, they significantly decreased (p = 0.045 and p = 0.039, respectively). In women with endometriosis, endometrial Tregs were lower than in women without endometriosis overall (p = 0.050 as a proportion of all CD45+ immune cells). We have shown for the first time that proportions of CD4+ lymphocytes (p = 0.021), overall lymphocytes (p = 0.034) and non-granulocytes (p = 0.027) were significantly decreased in the endometrium of women with moderate-severe (r-ASRM stages III and IV) compared to minimal-mild (r-ASRM stages I and II) endometriosis. During the secretory phase, circulating Treg proportions were significantly increased in infertile compared to fertile women (p = 0.049). This study confirms differences in endometrial Tregs in women with endometriosis, with blunting of normal menstrual cyclical variations, reduced proportions during the proliferative phase and disease stage-specific relationships.

Comprehensive analysis utilizing flow cytometry and immunohistochemistry reveals inflammatory changes in local endometrial and systemic dendritic cell populations in endometriosis

STUDY QUESTION

What are the detailed endometrial tissue specific and systemic dendritic cell (DC) subset disturbances in endometriosis?

SUMMARY ANSWER

This study confirms myeloid DC (mDC) and plasmacytoid DC subsets are readily identified in endometrial tissue and shows both endometrial and circulating differences in DC populations in women with endometriosis, with disease stage-specific relationships evident locally in the endometrium.

WHAT IS KNOWN ALREADY

Immune factors in the uterus, the peritoneal environment and systemically are implicated in the pathogenesis and progression of both endometriosis and infertility. While there is some evidence that endometrial DC populations are altered in endometriosis, DC subset involvement in both the endometrium and peripheral blood have not been comprehensively investigated so the functional consequences have been unknown.

STUDY DESIGN, SIZE, DURATION

This prospective cross-sectional cohort study compares circulating and endometrial DC populations in women of reproductive age with and without endometriosis (n = 55 and 30, respectively), wherein each participant donated samples at a single time point. Study participants were surveyed for menstrual cycle phase, American Society for Reproductive Medicine (ASRM) endometriosis disease stage and fertility status (where possible).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Peripheral blood samples were processed into mononuclear cells for analysis by flow cytometry, and endometrial samples were analysed by immunohistochemistry and dissociated into single-cell suspension for flow cytometry.

MAIN RESULTS AND THE ROLE OF CHANCE

In the endometrium of women with endometriosis, IRF-8+ cells were increased during the proliferative phase (P = 0.014), total DC proportions increased in the secretory phase (P = 0.038) and normal menstrual cyclical fluctuations in CD1c+ and IRF-8+ cells blunted; indicative of a consistently inflammatory tissue environment. The inflammatory changes in CD141+ and IRF-8+ populations in the endometrium of women with endometriosis were particularly evident in more advanced ASRM stages of the disease (respective P-values 0.032 and 0.045). There was also evidence of systemic inflammation in women with endometriosis, with increased circulating CD141+ mDC proportions (overall P = 0.040, secretory phase P = 0.021).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

As is common in this type of study, one of the main limitations was small sample numbers, particularly during the menstrual phase of the cycle.

WIDER IMPLICATIONS OF THE FINDINGS

Further phenotyping of local and circulating immune cell subtypes is critical to improving understanding of endometriosis pathogenesis and immune contributions to infertility associated with the disease.

STUDY FUNDING/COMPETING INTEREST(S)

This research was financially supported by a Sydney Medical School and Balnaves Foundation Kick Start Grant and the Department of Obstetrics, Gynaecology and Neonatology at The University of Sydney. The authors have no conflicts of interest to declare.

Nerve fibre infiltration and expression in peritoneal lesions of endometriosis in a nonhuman primate model of endometriosis

Baboon ( Papio anubis) models of endometriosis are thought to mimic the early stages of spontaneous human peritoneal endometriotic disease. The objective of this study was to investigate the presence and course of nerve fibre ingrowth during peritoneal lesion formation in specimens collected at 3 months (early stage of lesion development) and 15 months (late stage of lesion development) after disease initiation compared to pelvic peritoneum (control). Five-micron sections of paraffin-embedded peritoneal lesions were obtained from normally cycling baboons with 3-month (n = 12), 15-month (n = 12) induced endometriosis and pelvic peritoneum (n = 10) from baboons with no endometriosis. Immunohistochemical staining was performed with specific antibodies: protein gene product 9.5 – broad marker of nerve fibres and neurones, neuropeptide Y – sympathetic neurones, substance P – sensory neurones, vasoactive intestinal peptide – parasympathetic neurones, nerve growth factor – development of new neurones and high-affinity receptor for nerve growth factor (tropomyosin receptor kinase A) – neuronal differential. Significantly, more nerve fibres were identified in peritoneal endometriotic lesions collected 15 months after the initiation of experimental protocols compared with 3-month and control samples (p < 0.001). Nerve fibres were immunoreactive for all the tested markers – protein gene product 9.5, neuropeptide Y, substance P, vasoactive intestinal peptide, nerve growth factor and tropomyosin receptor kinase A – indicating the presence of different types of nerve fibres. In conclusion, peritoneal lesions of endometriosis in a nonhuman primate model of endometriosis were found to be progressively and spontaneously innervated by both myelinated and unmyelinated sensory nerve fibres, parasympathetic and sympathetic neurones. These nerve fibres may play an important role in the mechanisms of pain generation in this condition.

Uterine Lymphatic and Blood Micro-Vessels in Women with Endometriosis through the Menstrual Cycle

Purpose

Endometriosis is a common disease, associated with persistent and severe symptoms including infertility and pain, however, pathogenesis remains poorly understood. It has been hypothesized that fragments of viable endometrial tissue shed at menstruation reach the peritoneal cavity and other distant sites by retrograde menstruation and dissemination into the lymphatic system. In this study, uterine lymphatic and blood micro-vessel populations were compared in women with and without endometriosis during the menstrual cycle.

Methods

Paraffin-embedded hysterectomy specimens from premenopausal women with histologically normal endometrium (37 control and 42 endometriosis) were obtained. Immunohistochemical staining was performed with antibodies for D2–40 (lymphatic endothelium), CD31 (pan-endothelial marker), and endoglin (activated endothelial cells in angiogenesis). Lymphatic (LVD) and blood (BVD) micro-vessel density were quantified with an automated cellular imaging system using color and morphometric properties to identify micro-vessels.

Results

Subtle but significant differences in uterine BVD and LVD were detected in endometriosis. LVD was significantly increased in basal layer endometrium of endometriosis patients during the proliferative phase (mean ± SD = 54.3 ± 20.1 vs. 41.4 ± 9.9, p = 0.025). Endoglin-positive BVD was increased in the subepithelial region of endometrium in endometriosis during the secretory phase (19.3 ± 16.6 vs. 6.4 ± 8.2, p = 0.038).

Conclusions

This report for the first time demonstrates that endometrial LVD is altered in women with endometriosis and supports changes in BVD in these women. These alterations are likely to contribute to pathogenesis of endometriosis, through lymphatic spread and increased angiogenic potential of shed endometrial fragments.

Endometrial biomarkers for the non-invasive diagnosis of endometriosis

BACKGROUND

About 10% of reproductive-aged women suffer from endometriosis, which is a costly, chronic disease that causes pelvic pain and subfertility. Laparoscopy is the gold standard diagnostic test for endometriosis, but it is expensive and carries surgical risks. Currently, there are no non-invasive tests available in clinical practice that accurately diagnose endometriosis. This is the first diagnostic test accuracy review of endometrial biomarkers for endometriosis that utilises Cochrane methodologies, providing an update on the rapidly expanding literature in this field.

OBJECTIVES

To determine the diagnostic accuracy of the endometrial biomarkers for pelvic endometriosis, using a surgical diagnosis as the reference standard. We evaluated the tests as replacement tests for diagnostic surgery and as triage tests to inform decisions to undertake surgery for endometriosis.

SEARCH METHODS

We did not restrict the searches to particular study designs, language or publication dates. To identify trials, we searched the following databases: CENTRAL (2015, July), MEDLINE (inception to May 2015), EMBASE (inception to May 2015), CINAHL (inception to April 2015), PsycINFO (inception to April 2015), Web of Science (inception to April 2015), LILACS (inception to April 2015), OAIster (inception to April 2015), TRIP (inception to April 2015) and ClinicalTrials.gov (inception to April 2015). We searched DARE and PubMed databases up to April 2015 to identify reviews and guidelines as sources of references to potentially relevant studies. We also performed searches for papers recently published and not yet indexed in the major databases. The search strategies incorporated words in the title, abstract, text words across the record and the medical subject headings (MeSH).

SELECTION CRITERIA

We considered published peer-reviewed, randomised controlled or cross-sectional studies of any size that included prospectively collected samples from any population of reproductive-aged women suspected of having one or more of the following target conditions: ovarian, peritoneal or deep infiltrating endometriosis (DIE).

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from each study and performed a quality assessment. For each endometrial diagnostic test, we classified the data as positive or negative for the surgical detection of endometriosis and calculated the estimates of sensitivity and specificity. We considered two or more tests evaluated in the same cohort as separate data sets. We used the bivariate model to obtain pooled estimates of sensitivity and specificity whenever sufficient data were available. The predetermined criteria for a clinically useful test to replace diagnostic surgery was one with a sensitivity of 94% and a specificity of 79%. The criteria for triage tests were set at sensitivity at or above 95% and specificity at or above 50%, which in case of negative results rules out the diagnosis (SnOUT test) or sensitivity at or above 50% with specificity at or above 95%, which in case of positive result rules in the diagnosis (SpIN test).

MAIN RESULTS

We included 54 studies involving 2729 participants, most of which were of poor methodological quality. The studies evaluated endometrial biomarkers either in specific phases of the menstrual cycle or outside of it, and the studies tested the biomarkers either in menstrual fluid, in whole endometrial tissue or in separate endometrial components. Twenty-seven studies evaluated the diagnostic performance of 22 endometrial biomarkers for endometriosis. These were angiogenesis and growth factors (PROK-1), cell-adhesion molecules (integrins α3β1, α4β1, β1 and α6), DNA-repair molecules (hTERT), endometrial and mitochondrial proteome, hormonal markers (CYP19, 17βHSD2, ER-α, ER-β), inflammatory markers (IL-1R2), myogenic markers (caldesmon, CALD-1), neural markers (PGP 9.5, VIP, CGRP, SP, NPY, NF) and tumour markers (CA-125). Most of these biomarkers were assessed in single studies, whilst only data for PGP 9.5 and CYP19 were available for meta-analysis. These two biomarkers demonstrated significant diversity for the diagnostic estimates between the studies; however, the data were too limited to reliably determine the sources of heterogeneity. The mean sensitivities and specificities of PGP 9.5 (7 studies, 361 women) were 0.96 (95% confidence interval (CI) 0.91 to 1.00) and 0.86 (95% CI 0.70 to 1.00), after excluding one outlier study, and for CYP19 (8 studies, 444 women), they were were 0.77 (95% CI 0.70 to 0.85) and 0.74 (95% CI 0.65 to 84), respectively. We could not statistically evaluate other biomarkers in a meaningful way. An additional 31 studies evaluated 77 biomarkers that showed no evidence of differences in expression levels between the groups of women with and without endometriosis.

AUTHORS' CONCLUSIONS

We could not statistically evaluate most of the biomarkers assessed in this review in a meaningful way. In view of the low quality of most of the included studies, the findings of this review should be interpreted with caution. Although PGP 9.5 met the criteria for a replacement test, it demonstrated considerable inter study heterogeneity in diagnostic estimates, the source of which could not be determined. Several endometrial biomarkers, such as endometrial proteome, 17βHSD2, IL-1R2, caldesmon and other neural markers (VIP, CGRP, SP, NPY and combination of VIP, PGP 9.5 and SP) showed promising evidence of diagnostic accuracy, but there was insufficient or poor quality evidence for any clinical recommendations. Laparoscopy remains the gold standard for the diagnosis of endometriosis, and using any non-invasive tests should only be undertaken in a research setting. We have also identified a number of biomarkers that demonstrated no diagnostic value for endometriosis. We recommend that researchers direct future studies towards biomarkers with high diagnostic potential in good quality diagnostic studies.

Identification of multiple pathways involved in the malignant transformation of endometriosis (Review)

The association between endometriosis and malignant transformation has often been described in the medical literature. A search was conducted between 1966 and 2010 through the English language literature (online Medline PubMed database) using the keywords endometriosis combined with malignant transformation. The search revealed an increase in reports describing endometriosis and malignancy. Approximately 1.0% of women with endometriosis have lesions that undergo malignant transformation. The malignant processes that are associated with endometriosis may be classified into three groups: i) epithelial ovarian cancers (endometrioid adenocarcinoma and clear cell carcinoma), ii) other Müllerian-type tumors, including Müllerian-type mucinous borderline tumor and serous borderline tumor and iii) sarcomas such as adenosarcoma and endometrial stromal sarcoma in the female pelvic cavity. Persistent oxidative stress induced by endometriosis-dependent hemorrhage may be associated with carcinogenesis. In conclusion, the malignant transformation of endometriosis has multiple pathways of development and may share a common pathogenic mechanism; iron-induced oxidative stress derived from repeated hemorrhage.

Endometrial stromal cells and immune cell populations within lymph nodes in a nonhuman primate model of endometriosis

Mounting evidence suggests that immunological responses may be altered in endometriosis. The baboon (Papio anubis) is generally considered the best model of endometriosis pathogenesis. The objective of the current study was to investigate for the first time immunological changes within uterine and peritoneal draining lymph nodes in a nonhuman primate baboon model of endometriosis. Paraffin-embedded femoral lymph nodes were obtained from 22 normally cycling female baboons (induced endometriosis n = 11; control n = 11). Immunohistochemical staining was performed with antibodies for endometrial stromal cells, T cells, immature and mature dendritic cells, and B cells. Lymph nodes were evaluated using an automated cellular imaging system. Endometrial stromal cells were significantly increased in lymph nodes from animals with induced endometriosis, compared to control animals (P = .033). In animals with induced endometriosis, some lymph node immune cell populations including T cells, dendritic cells and B cells were increased, suggesting an efficient early response or peritoneal drainage.