The link between immunity, autoimmunity and endometriosis: a literature update

Long-term pituitary downregulation before frozen embryo transfer improves clinical outcomes in women positive for serum autoantibodies

OBJECTIVE

Autoantibodies are associated with worse outcomes in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI), including increasing miscarriage rate, lowering pregnancy rate, and lowering delivery rate. However, little is known about improving IVF/ICSI outcomes for autoantibody-positive women, especially in frozen-thawed embryo transfer (FET) cycles. This study aimed to investigate whether pituitary suppression before FET improves the clinical pregnancy rate (CPR) and live birth rate (LBR) for IVF/ICSI women positive for serum autoantibodies.

STUDY DESIGN

A total of 181 infertile women positive for serum autoantibodies were recruited, including 65 women receiving GnRHa and hormone replacement therapy protocols (G-HRT group) and 116 women using modified natural cycles (MNC)/mild stimulated cycles (MSC) as FET protocols (MNC/MSC group). The outcomes were compared between two groups, including CPR, implantation rate (IR), miscarriage rate (MR), ongoing pregnancy rate (OPR), LBR, and gestational age (GA). The primary outcome of the study was CPR.

RESULTS

CPR, OPR, and LBR per embryo transferred in the G-HRT groups were significantly higher than those in the MNC/MSC group. No statistically significant differences were observed in the IR and MR. The CPR, IR, MR, OPR, and LBR was 72.23%, 64.00%, 12.77%, 63.07%, and 63.07% in the G-HRT group, respectively, while that was 56.90%, 53.07%, 10.60%, 50.00%, and 50.00% in the MNC/MSC group, respectively. After adjusting for partial potential confounding factors using multiple logistic regression, the type of endometrial preparation is the factor independently associated with enhanced CPR (OR = 0.48, 95%CI: 0.24-0.96, P = 0.039).

CONCLUSIONS

The current study showed that prior long-term GnRHa suppression could benefit patients with high serum autoantibody levels during IVF/ICSI FET cycles.

Endometriotic Peritoneal Fluid Stimulates Recruitment of CD4+CD25highFOXP3+ Treg Cells

Endometriosis is a common gynecological disorder characterized by the presence of endometrial-like tissue outside the uterus. The disease is associated with disturbed local and systemic immunity. It has been reported that the proportion of CD4⁺CD25^highFOXP3⁺ Treg cells may be significantly increased in the peritoneal fluid of patients with endometriosis. Therefore, the aim of our study was to investigate whether the proportions of Treg cells in the peritoneal cavity of patients with endometriosis are related to the chemotactic and stimulatory activity of the local peritoneal milieu. The peritoneal fluid was collected from 13 women with ovarian endometriosis and 12 control women without the disease. T cell populations were analyzed by flow cytometry, cytokines and chemokines were evaluated using the cytometric bead kit, and cell chemotaxis was studied by cell migration assay. We confirmed that the proportions of Treg cells are increased in the peritoneal fluid of women with endometriosis as compared to the control women. Endometriosis was also associated with elevated concentrations of IL-6, IL-10, and TGF-β1/2 as well as CCL20, CXCL8, CXCL9, and CXCL10. We did not reveal any changes in the proportion of peritoneal Th17 cells and concentrations of IL-17A. Peritoneal Treg cells positively correlated with concentrations of TGF-β, IL-10, and CCL20. Endometriotic peritoneal fluid stimulated chemotaxis of both CD4⁺ and Treg cells. This chemotactic activity positively correlated with concentrations of CCL20. CCL20 stimulated the migration of Treg cells, and the chemotactic activity of the endometriotic peritoneal fluid was inhibited by neutralizing anti-CCL20 antibodies. These results imply that increased proportions of the peritoneal Treg cells in women with endometriosis may result from attraction and activation by local chemokines and cytokines, especially CCL20 and TGF-β. Since Treg cells contribute to the immunopathogenesis of endometriosis, their chemotaxis and activation may be considered as a target for therapeutic intervention.

Pentoxifylline for the treatment of endometriosis-associated pain and infertility

BACKGROUND

Endometriosis is a chronic inflammatory condition that occurs during the reproductive years. It is characterised by endometrium-like tissue developing outside the uterine cavity. This endometriotic tissue development is dependent on oestrogen produced primarily by the ovaries and partially by the endometriotic tissue itself, therefore traditional management has focused on ovarian suppression. In this review we considered the role of modulation of the immune system as an alternative approach. This is an update of a Cochrane Review previously published in 2012.

OBJECTIVES

To determine the effectiveness and safety of pentoxifylline in the management of endometriosis.  SEARCH METHODS: We searched the Cochrane Gynaecology and Fertility (CGF) Group Trials Register, CENTRAL, MEDLINE, Embase, PsycINFO, and AMED on 16 December 2020, together with reference checking and contact with study authors and experts in the field to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing pentoxifylline with placebo or no treatment, other medical treatment, or surgery in women with endometriosis. The primary outcomes were live birth rate and overall pain (as measured by a visual analogue scale (VAS) of pain, other validated scales, or dichotomous outcomes) per woman randomised. Secondary outcomes included clinical pregnancy rate, miscarriage rate, rate of recurrence, and adverse events resulting from the pentoxifylline intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies against the inclusion criteria, extracted data, and assessed risk of bias, consulting a third review author where required. We contacted study authors as needed. We analysed dichotomous outcomes using Mantel-Haenszel risk ratios (RRs), 95% confidence intervals (CIs), and a fixed-effect model. For small numbers of events, we used a Peto odds ratio (OR) with 95% CI instead. We analysed continuous outcomes using the mean difference (MD) between groups presented with 95% CIs. We used the I² statistic to evaluate heterogeneity amongst studies. We employed the GRADE approach to assess the quality of the evidence.

MAIN RESULTS

We included five parallel-design RCTs involving a total of 415 women. We included one additional RCT in this update. Three studies did not specify details relating to allocation concealment, and two studies were not blinded. There were also considerable loss to follow-up, with four studies not conducting intention-to-treat analysis. We judged the quality of the evidence as very low. Pentoxifylline versus placebo No trials reported on our primary outcomes of live birth rate and overall pain. We are uncertain as to whether pentoxifylline treatment affects clinical pregnancy rate when compared to placebo (RR 1.38, 95% CI 0.91 to 2.10; 3 RCTs, n = 285; I² = 0%; very low-quality evidence). The evidence suggests that if the clinical pregnancy rate with placebo is estimated to be 20%, then the rate with pentoxifylline is estimated as between 18% and 43%. We are also uncertain as to whether pentoxifylline affects the recurrence rate of endometriosis (RR 0.84, 95% CI 0.30 to 2.36; 1 RCT, n = 121; very low-quality evidence) or miscarriage rate (Peto OR 1.99, 95% CI 0.20 to 19.37; 2 RCTs, n = 164; I² = 0%; very low-quality evidence). No trials reported on the effect of pentoxifylline on improvement of endometriosis-related symptoms other than pain or adverse events. Pentoxifylline versus no treatment No trials reported on live birth rate. We are uncertain as to whether pentoxifylline treatment affects overall pain when compared to no treatment at one month (MD -0.36, 95% CI -2.12 to 1.40; 1 RCT, n = 34; very low-quality evidence), two months (MD -1.25, 95% CI  -2.67 to 0.17; 1 RCT, n = 34; very low-quality evidence), or three months (MD -1.60, 95% CI -3.32 to 0.12; 1 RCT, n = 34; very low-quality evidence). No trials reported on adverse events caused by pentoxifylline or any of our other secondary outcomes. Pentoxifylline versus other medical therapies One study (n = 83) compared pentoxifylline to the combined oral contraceptive pill after laparoscopic surgery to treat endometriosis, but could not be included in the meta-analysis as it was unclear if the data were presented as +/- standard deviation and what the duration of treatment was. No trials reported on adverse events caused by pentoxifylline or any of our other secondary outcomes. Pentoxifylline versus conservative surgical treatment  No study reported on this comparison.

AUTHORS' CONCLUSIONS

No studies reported on our primary outcome of live birth rate. Due to the very limited evidence, we are uncertain of the effects of pentoxifylline on clinical pregnancy rate, miscarriage rate, or overall pain. There is currently insufficient evidence to support the use of pentoxifylline in the management of women with endometriosis with respect to subfertility and pain relief outcomes.

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.

Organization of the Cytoskeleton in Ectopic Foci of the Endometrium with Rare Localization

(1) Background: Endometriosis is a common pathology of the female reproductive system, often accompanied by pain and decreased fertility. However, its pathogenesis has not been sufficiently studied regarding the role of the cytoskeleton. In this study, we describe two clinical cases involving rare localization of extragenital endometriosis (umbilicus) and compare them with genital endometriosis of different localization (ovaries and uterus), as well as eutopic endometrium obtained with separate diagnostic curettage without confirmed pathology. (2) Methods: The relative content of actin and tubulin cytoskeleton proteins was determined by Western blotting, and the expression of genes encoding these proteins was determined by RT-PCR in the obtained intraoperative biopsies. The content of 5hmC was estimated by dot blot experiments, and the methylase/demethylase and acetylase/deacetylase contents were determined. (3) Results: The obtained results indicate that the content of the actin-binding protein alpha-actinin1 significantly increased (p < 0.05) in the groups with endometriosis, and this increase was most pronounced in patients with umbilical endometriosis. In addition, both the mRNA content of the ACTN1 gene and 5hmC content increased. It can be assumed that the increase in 5hmC is associated with a decrease in the TET3 demethylase content. Moreover, in the groups with extragenital endometriosis, alpha- and beta-tubulin content was decreased (p < 0.05) compared to the control levels. (4) Conclusions: In analyzing the results, further distance of ectopic endometrial foci from the eutopic localization may be associated with an increase in the content of alpha-actinin1, probably due to an increase in the expression of its gene and an increase in migration potential. In this case, a favorable prognosis can be explained by a decrease in tubulin content and, consequently, a decrease in the rate of cell division.

Peritoneal Fluid from Patients with Ovarian Endometriosis Displays Immunosuppressive Potential and Stimulates Th2 Response

Endometriosis is a common gynaecological disorder characterized by the ectopic growth of endometrial tissue outside the uterine cavity. It is associated with chronic pelvic inflammation and autoimmune reactivity manifesting by autoantibody production and abrogated cellular immune responses. Endometriotic peritoneal fluid contains various infiltrating leucocyte populations and a bulk of proinflammatory and immunoregulatory cytokines. However, the nature and significance of the peritoneal milieu in women with endometriosis still remains obscure. Therefore, the aim of the present study was to investigate the immunoregulatory activity of the peritoneal fluid (PF) from women with endometriosis. The peritoneal fluid samples were collected during laparoscopic surgery from 30 women with and without endometriosis. Immunoregulatory cytokines (IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-γ and TNF) and chemokines (CCL2, CCL5, CXCL8 and CXCL9) were evaluated in PF and culture supernatants generated by unstimulated and CD3/CD28/IL-2-stimulated CD4⁺ T cells cultured in the presence of PF. The effect of PF on the generation of Treg and Th17 cells in CD4⁺ T cell cultures, as well as the natural cytotoxic activity of peripheral blood mononuclear cells, was also investigated. Concentrations of IL-6, IL-10, CCL2, CXCL8 and CXCL9 were significantly upregulated in the PF from women with endometriosis when compared to control women, whereas concentrations of other cytokines and chemokines were unaffected. The culturing of unstimulated and CD3/CD28/IL-2-stimulated CD4⁺ T cells in the presence of endometriotic PF resulted in the downregulation of their IL-2, IFN-γ, IL-17A and TNF production as compared to culture medium alone. On the other side, endometriotic PF significantly stimulated the production of IL-4 and IL-10. Endometriotic PF also stimulated the release of CCL2 and CXCL8, whereas the production of CCL5 and CXCL9 was downregulated. Endometriotic PF stimulated the generation of Treg cells and had an inhibitory effect on the generation of Th17 cells in cultures of CD4⁺ T cells. It also inhibited the NK cell cytotoxic activity of the peripheral blood lymphocytes. These results strongly imply that the PF from patients with endometriosis has immunoregulatory/immunosuppressive activity and shifts the Th1/Th2 cytokine balance toward the Th2 response, which may account for deviation of local and systemic immune responses. However, a similar trend, albeit not a statistically significant one, was also observed in case of PF from women without endometriosis, thus suggesting that peritoneal milieu may in general display some immunoregulatory/immunosuppressive properties. It should be stressed, however, that our present observations were made on a relatively small number of PF samples and further studies are needed to reveal possible mechanism(s) responsible for this phenomenon.

Concomitant autoimmunity may be a predictor of more severe stages of endometriosis

Pathogenesis of endometriosis is still unclear and a role of both innate and adaptive immune system has been postulated. Some recent findings have revealed an increased risk to have concomitant autoimmune disease in women with endometriosis, but no study so far has investigated whether this association could affect endometriosis severity and stage. We retrospectively reviewed medical patients' notes of women with a confirmed diagnosis of endometriosis who referred to our endometriosis outpatient clinic between January 2015 and December 2019. Cases (endometriosis and an autoimmune disease) were matched in a 1:3 ratio by age and study period with controls (endometriosis without history of autoimmunity). At univariate logistic analysis, concomitant autoimmunity (OR 2.63, 95% CI 1.64-4.21, p < 0.001) and the number of laparoscopic procedures performed (OR 2.81, 95% CI 1.45-5.43, p = 0.002) emerged as factors significantly associated with the likelihood of stage IV endometriosis. In the multivariate logistic regression model, concomitant autoimmunity remained a significant predictor of stage IV endometriosis (OR 2.54, 95% CI 1.57-4.10, p = 0.004), whereas the association between the number of laparoscopic procedures performed and stage IV endometriosis was found to be of borderline-significance (OR 2.70, 95% 1.37-5.30, p = 0.050). Our findings suggest that endometriosis is more severe in patients who are also affected by autoimmune disturbances after controlling for relevant confounders.

Anesthetic Bladder Capacity is a Clinical Biomarker for Interstitial Cystitis/Bladder Pain Syndrome Subtypes

OBJECTIVE

To further examine anesthetic bladder capacity as a biomarker for interstitial cystitis/bladder pain syndrome (IC/BPS) patient subtypes, we evaluated demographic and clinical characteristics in a large and heterogeneous female patient cohort.

MATERIAL AND METHODS

This is a retrospective review of data from women (n = 257) diagnosed with IC/BPS who were undergoing therapeutic bladder hydrodistention (HOD). Assessments included medical history and physical examination, validated questionnaire scores, and anesthetic BC. Linear regression analyses were computed to model the relationship between anesthetic BC and patient demographic data, symptoms, and diagnoses. Variables exhibiting suggestive correlations (P ≤ .1) were candidates for a multiple linear regression analysis and were retained if significant (P ≤ .05).

RESULTS

Multiple regression analysis identified a positive correlation between BC and endometriosis (P = .028) as well as negative correlations between BC and both ICSI score (P < .001) and the presence of Hunner's lesions (P < .001). There were higher average numbers of pelvic pain syndrome (PPS) diagnoses (P = .006) and neurologic, autoimmune, or systemic pain (NASP) diagnoses (P = .003) in IC/BPS patients with a non-low BC, but no statistical difference in the duration of diagnosis between patients with low and non-low BC (P = .118).

CONCLUSION

These data, generated from a large IC/BPS patient cohort, provide additional evidence that higher BC correlates with higher numbers of non-bladder-centric syndromes while lower BC correlates more closely with bladder-specific pathology. Taken together, the results support the concept of clinical subgroups in IC/BPS.

Network Pharmacology-Based Prediction of Bioactive Compounds and Potential Targets of Wenjing Decoction for Treatment of Endometriosis

Endometriosis is a chronic estrogen-dependent inflammatory disorder that negatively affects the quality of life in women. The Wenjing decoction (WJD) is a traditional Chinese medicine that has been shown to have a therapeutic effect on endometriosis. Our study systematically explored the mechanism of WJD against endometriosis using a network pharmacology approach. Potentially bioactive compounds of WJD and their possible targets were retrieved from the Traditional Chinese Medicine System Pharmacology Database and Analysis Platform. The protein-protein interaction network and herbs-compounds-genes multinetwork were constructed using Cytoscape for visualization. Subsequently, the signaling pathways of common targets were retrieved from the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, and molecular docking was performed using PyRx software. In total, 48 common targets were screened, such as IL6 and ESR1, which were related to inflammation and the endocrine system. The top five bioactive compounds were quercetin, kaempferol, wogonin, beta-sitosterol, and stigmasterol. KEGG enrichment analysis revealed 65 pathways containing inflammatory- and endocrine-related signaling pathways, such as the "TNF signaling pathway" and the "estrogen signaling pathway." Taken together, the results of our network pharmacology analysis predicted that certain active ingredients of WJD might treat endometriosis by regulating inflammation and/or endocrine, which provided references for further understanding and exploration of WJD on endometriosis.

Pharmaceuticals targeting signaling pathways of endometriosis as potential new medical treatment: A review

Endometriosis (EM) is defined as endometrial tissues found outside the uterus. Growth and development of endometriotic cells in ectopic sites can be promoted via multiple pathways, including MAPK/MEK/ERK, PI3K/Akt/mTOR, NF-κB, Rho/ROCK, reactive oxidative stress, tumor necrosis factor, transforming growth factor-β, Wnt/β-catenin, vascular endothelial growth factor, estrogen, and cytokines. The underlying pathophysiological mechanisms include proliferation, apoptosis, autophagy, migration, invasion, fibrosis, angiogenesis, oxidative stress, inflammation, and immune escape. Current medical treatments for EM are mainly hormonal and symptomatic, and thus the development of new, effective, and safe pharmaceuticals targeting specific molecular and signaling pathways is needed. Here, we systematically reviewed the literature focused on pharmaceuticals that specifically target the molecular and signaling pathways involved in the pathophysiology of EM. Potential drug targets, their upstream and downstream molecules with key aberrant signaling, and the regulatory mechanisms promoting the growth and development of endometriotic cells and tissues were discussed. Hormonal pharmaceuticals, including melatonin, exerts proapoptotic via regulating matrix metallopeptidase activity while nonhormonal pharmaceutical sorafenib exerts antiproliferative effect via MAPK/ERK pathway and antiangiogenesis activity via VEGF/VEGFR pathway. N-acetyl cysteine, curcumin, and ginsenoside exert antioxidant and anti-inflammatory effects via radical scavenging activity. Natural products have high efficacy with minimal side effects; for example, resveratrol and epigallocatechin gallate have multiple targets and provide synergistic efficacy to resolve the complexity of the pathophysiology of EM, showing promising efficacy in treating EM. Although new medical treatments are currently being developed, more detailed pharmacological studies and large sample size clinical trials are needed to confirm the efficacy and safety of these treatments in the near future.

A deep insight into pelvic pain and endometriosis: a review of the literature from pathophysiology to clinical expressions

Endometriosis is a chronic inflammatory disease that affects approximately 10% of women of reproductive age. Its clinical manifestations are highly heterogeneous, but pelvic pain is the most frequent, causing functional disability. Cyclic or acyclic chronic pelvic pain (CPP), dysmenorrhea and dyspareunia are frequent symptoms which often compromise all aspects of the women's quality of life (QoL). The pathophysiology of endometriosis-related pain is extremely complex and not always clear. The aim of this literature review is to focus on recent updates on the clinical presentation, the pathophysiology and the most important mechanisms involved in the pathogenesis of pelvic pain in endometriosis. A literature search in the Cochrane library, PubMed, Scopus and web of Science databases has been performed, identifying articles from January 1995 to November 2020. Several processes seem to be involved in the pathogenesis of pain, but many aspects are still unclear. Scientific evidence has shown that a correlation between pain severity and stage of endometriosis rarely occurs, whereas there is a significant correlation between pain and the presence of deep endometriosis. Onset and intensity of pain may be due to a complex process involving central sensitization and peripheral activation of nociceptive pathways as well as dysfunction of the immune system and of the hypothalamic-pituitary-adrenal (HPA) axis. A deeper understanding of these different pathogenetic mechanisms may improve future treatments in women with painful endometriosis.

Knockdown of lncRNA H19 suppresses endometriosis in vivo

The long noncoding RNA (lncRNA) H19 is involved in the pathogenesis of endometriosis by modulating the proliferation and invasion of ectopic endometrial cells in vitro, but related in vivo studies are rare. This study aimed to investigate the role of lncRNA H19 in a nude mouse model of endometriosis. Ectopic endometrial stromal cells (ecESCs) were isolated from ectopic endometrium of patients with endometriosis and infected with lentiviruses expressing short hairpin RNA (shRNA) negative control (LV-NC-shRNA) or lncRNA-H19 shRNA (LV-H19-shRNA). The ecESCs infected with LV-NC-shRNA and LV-H19-shRNA were subcutaneously implanted into forty 6- to 8-week-old female nude mice. The size and weight of the endometriotic implants were measured at 1, 2, 3, and 4 weeks after implantation and compared, and lncRNA H19 levels in endometriotic implants were evaluated using real-time polymerase chain reaction (RT-PCR). All nude mice survived the experimental period, and no significant differences in body weight were observed between the experimental group and the control group. All nude mice developed histologically confirmed subcutaneous endometriotic lesions with glandular structures and stroma after 1 week of implantation. The subcutaneous lesions in the LV-NC-shRNA group after 1, 2, 3, and 4 weeks of implantation were larger than those in the LV-H19-shRNA group, and lncRNA H19 levels in subcutaneous lesions in the LV-NC-shRNA group were significantly higher than those in the LV-H19-shRNA group. Knockdown of lncRNA H19 suppresses endometriosis in vivo. Further study is required to explore the underlying mechanism in the future.

Caesalpinia sappan induces apoptotic cell death in ectopic endometrial 12Z cells through suppressing pyruvate dehydrogenase kinase 1 expression

Endometriosis is a common gynecological disease defined as the growth of endometrial tissues outside the uterus. Although the mechanism underlying the progression of endometriosis has not been fully elucidated, cancer-like aerobic glycolysis is considered to mediate the elevated growth and resistance to apoptosis of endometriotic cells. The heartwood of Caesalpinia sappan L. (family Leguminosae) is a herbal medicinal product used to treat gynecological symptoms, including algomenorrhea and amenorrhea. The results of the present study revealed that endometriotic 12Z cells exhibited more rapid growth than normal endometrial cells (THES). The expression levels of pyruvate dehydrogenase kinase (PDK)1 and 3 and lactate production were higher in 12Z cells than in THES cells. In addition, the 12Z cells were more sensitive to the cytotoxicity of the aqueous extract of C. sappan heartwood (CS) than the THES cells. CS inhibited lactate production and phosphorylation of pyruvate dehydrogenase A by reducing the expression of PDK1. CS also increased mitochondrial reactive oxygen species (ROS) levels, decreased mitochondrial membrane potential and consequently stimulated the apoptosis of 12Z cells. CS-induced cell death was substantially inhibited by exogenous PDK1 expression. In conclusion, CS may be a novel drug candidate for treating endometriosis by inhibiting aerobic glycolysis and inducing ROS-mitochondria-mediated apoptotic cell death.

Insights into the role of complement system in the pathophysiology of endometriosis

Endometriosis (EM) is a gynecologic disorder characterized by the presence of endometrium-like tissue outside of normal location that affects up to 10 % of all women in reproductive age. The pathogenesis of endometriosis is not completely known. The relationship between complement and EM has already been demonstrated in some studies, indicating an important role in the pathophysiology of the disease, however, researches are scarce and sometimes controversial. The objective of this review is to bring state-of-the-art knowledge on the subject and promote better understanding of the complement system role in the pathophysiology of EM. We searched in databases up to December 2020 and found 1213 articles that were screened, from which were selected 54 articles from title and abstract. We found that there is a dysfunction of the immune system on endometriosis, including the complement system. Apparently, the complement system is dysregulated in endometriosis and several proteins of the three complement pathways presented serum levels altered in women with endometriosis compared with those without the disease. The most studied protein is C3. Future investigations on the innate immune response and complement system could offer a further understanding on the inflammatory pathogenesis of EM, which will support a new therapeutic plan.

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.

Brassica Bioactives Could Ameliorate the Chronic Inflammatory Condition of Endometriosis

Endometriosis is a chronic, inflammatory, hormone-dependent disease characterized by histological lesions produced by the presence of endometrial tissue outside the uterine cavity. Despite the fact that an estimated 176 million women are affected worldwide by this gynecological disorder, risk factors that cause endometriosis have not been properly defined and current treatments are not efficient. Although the interaction between diet and human health has been the focus of many studies, little information about the correlation of foods and their bioactive derivates with endometriosis is available. In this framework, Brassica crops have emerged as potential candidates for ameliorating the chronic inflammatory condition of endometriosis, due to their abundant content of health-promoting compounds such as glucosinolates and their hydrolysis products, isothiocyanates. Several inflammation-related signaling pathways have been included among the known targets of isothiocyanates, but those involving aquaporin water channels have an important role in endometriosis. Therefore, the aim of this review is to highlight the promising effects of the phytochemicals present in Brassica spp. as major candidates for inclusion in a dietary approach aiming to improve the inflammatory condition of women affected with endometriosis. This review points out the potential roles of glucosinolates and isothiocyanates from Brassicas as anti-inflammatory compounds, which might contribute to a reduction in endometriosis symptoms. In view of these promising results, further investigation of the effect of glucosinolates on chronic inflammatory diseases, either as diet coadjuvants or as therapeutic molecules, should be performed. In addition, we highlight the involvement of aquaporins in the maintenance of immune homeostasis. In brief, glucosinolates and the modulation of cellular water by aquaporins could shed light on new approaches to improve the quality of life for women with endometriosis.

Live-Birth Outcomes and Congenital Malformations After Progestin-Primed Ovarian Stimulation in Maternal Endometriosis

Purpose

In patients who had advanced endometriosis, we use different protocols including GnRH agonist, GnRH antagonist and progestin-primed ovarian stimulation (PPOS) protocols to assess live-birth congenital malformations delivered after in vitro fertilization (IVF) and vitrified embryo transfer cycles.

Methods

A retrospective cohort study is conducted by us. It includes 1495 live-born infants in maternal endometriosis. From January 2010 to January 2017, we brought into infants who underwent either gonadotropin-releasing hormone agonist long protocol, gonadotropin-releasing hormone antagonist protocol or PPOS. We chose neonatal outcomes and congenital malformations as our major measures.

Results

Neonatal outcomes, as well as congenital malformations, were considered as the main measures, and gestational age, birth weight, birth length, multiple births and early neonatal death are included. All groups were comparable. The GnRH antagonist group (1.41%) and the GnRH antagonist protocol group (1.8%) had the same incidence of live-birth defects as the PPOS groups (1.33%) were similar. There were no apparent differences when it came to congenital malformations among the three groups. Multivariate logistic regression showed that infertility-time factors as well as multiple births combined to add the risk of congenital malformations; the adjusted odds were 1.143 (95% confidence interval [CI]: 0.988–1.323) and 3.253 (95% CI: 1.359–7.788). Besides, no association was found among various ovarian stimulations as well as congenital birth defect programs, maternal age, body mass index, parity or infant sex.

Conclusion

This study suggests that, in contrast to conventional ovarian stimulation, PPOS neither has any effect on neonatal outcomes in IVF adverse effects nor does it elevate the rate of congenital malformations in late endometriosis. However, randomized controlled trials of the long-term outcomes of children born after PPOS protocols for maternal endometriosis are needed and the follow-up studies were conducted to confirm this result.

Hypothetical roadmap towards endometriosis: prenatal endocrine-disrupting chemical pollutant exposure, anogenital distance, gut-genital microbiota and subclinical infections

BACKGROUND

Endometriosis is a gynaecological hormone-dependent disorder that is defined by histological lesions generated by the growth of endometrial-like tissue out of the uterus cavity, most commonly engrafted within the peritoneal cavity, although these lesions can also be located in distant organs. Endometriosis affects ~10% of women of reproductive age, frequently producing severe and, sometimes, incapacitating symptoms, including chronic pelvic pain, dysmenorrhea and dyspareunia, among others. Furthermore, endometriosis causes infertility in ~30% of affected women. Despite intense research on the mechanisms involved in the initial development and later progression of endometriosis, many questions remain unanswered and its aetiology remains unknown. Recent studies have demonstrated the critical role played by the relationship between the microbiome and mucosal immunology in preventing sexually transmitted diseases (HIV), infertility and several gynaecologic diseases.

OBJECTIVE AND RATIONALE

In this review, we sought to respond to the main research question related to the aetiology of endometriosis. We provide a model pointing out several risk factors that could explain the development of endometriosis. The hypothesis arises from bringing together current findings from large distinct areas, linking high prenatal exposure to environmental endocrine-disrupting chemicals with a short anogenital distance, female genital tract contamination with the faecal microbiota and the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis.

SEARCH METHODS

We performed a search of the scientific literature published until 2019 in the PubMed database. The search strategy included the following keywords in various combinations: endometriosis, anogenital distance, chemical pollutants, endocrine-disrupting chemicals, prenatal exposure to endocrine-disrupting chemicals, the microbiome of the female reproductive tract, microbiota and genital tract, bacterial vaginosis, endometritis, oestrogens and microbiota and microbiota-immune system interactions.

OUTCOMES

On searching the corresponding bibliography, we found frequent associations between environmental endocrine-disrupting chemicals and endometriosis risk. Likewise, recent evidence and hypotheses have suggested the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis. Hence, we can envisage a direct relationship between higher prenatal exposure to oestrogens or estrogenic endocrine-disrupting compounds (phthalates, bisphenols, organochlorine pesticides and others) and a shorter anogenital distance, which could favour frequent postnatal episodes of faecal microbiota contamination of the vulva and vagina, producing cervicovaginal microbiota dysbiosis. This relationship would disrupt local antimicrobial defences, subverting the homeostasis state and inducing a subclinical inflammatory response that could evolve into a sustained immune dysregulation, closing the vicious cycle responsible for the development of endometriosis.

WIDER IMPLICATIONS

Determining the aetiology of endometriosis is a challenging issue. Posing a new hypothesis on this subject provides the initial tool necessary to design future experimental, clinical and epidemiological research that could allow for a better understanding of the origin of this disease. Furthermore, advances in the understanding of its aetiology would allow the identification of new therapeutics and preventive actions.

Risk of Rheumatoid Arthritis in Patients with Endometriosis: A Nationwide Population-Based Cohort Study

Background: Abnormalities in the immune system of endometriosis has been demonstrated and may reflect the chronic inflammatory response or the autoimmune reaction to the presence of ectopic endometrial tissue. Rheumatoid arthritis (RA) is a chronic inflammatory joint disease of an autoimmune nature. The study aimed to investigate the risk of incident RA in patients with endometriosis. Materials and Methods: A total of 17,913 patients with endometriosis and 17,913 unaffected controls matched by age, index year, and Charlson Comorbidity Index (CCI) score were enrolled between 2000 and 2012. Patients were followed until the end of 2013 using Taiwan's National Health Insurance Research Database, at which time participants who developed RA were identified. Cox regression analysis was used to calculate the hazard ratio (HR) with a 95% confidence interval (CI) of RA incidence rate between patients with endometriosis and unaffected controls. Results: Patients with endometriosis were associated with an increased risk of incident RA compared with unaffected controls after adjusting for age, CCI score, and hormonal and surgical treatments (3.56 vs. 1.30 per 10,000 person-years, HR: 3.71, 95% CI: 2.91-5.73). Among these adjusted variables, hormonal and surgical treatments were treated as time-dependent covariates. Stratification analyses also revealed similar risk associations linking endometriosis to subsequent RA in all stratified age and CCI score subgroups (adjusted HR all >1, although not all were significant) Conclusions: Patients with endometriosis was associated with an increased risk of incident RA. Additional prospective studies that take into account genetic vulnerability and environmental exposures are warranted to confirm this relationship.

Purinergic Signaling in Endometriosis-Associated Pain

Endometriosis is an estrogen-dependent gynecological disease, with an associated chronic inflammatory component, characterized by the presence of endometrial tissue outside the uterine cavity. Its predominant symptom is pain, a condition notably altering the quality of life of women with the disease. This review is intended to exhaustively gather current knowledge on purinergic signaling in endometriosis-associated pain. Altered extracellular ATP hydrolysis, due to changes in ectonucleotidase activity, has been reported in endometriosis; the resulting accumulation of ATP in the endometriotic microenvironment points to sustained activation of nucleotide receptors (P2 receptors) capable of generating a persistent pain message. P2X3 receptor, expressed in sensory neurons, mediates nociceptive, neuropathic, and inflammatory pain, and is enrolled in endometriosis-related pain. Pharmacological inhibition of P2X3 receptor is under evaluation as a pain relief treatment for women with endometriosis. The role of other ATP receptors is also discussed here, e.g., P2X4 and P2X7 receptors, which are involved in inflammatory cell–nerve and microglia–nerve crosstalk, and therefore in inflammatory and neuropathic pain. Adenosine receptors (P1 receptors), by contrast, mainly play antinociceptive and anti-inflammatory roles. Purinome-targeted drugs, including nucleotide receptors and metabolizing enzymes, are potential non-hormonal therapeutic tools for the pharmacological management of endometriosis-related pain.

Immune-Metabolic Therapy of Purulent Inflammatory Diseases

Introduction: Inflammatory diseases of the female genital organs rank among the leading ones in the total number of women of reproductive age. This results from a decrease in immunity, early sexual activity, neglect of personal hygiene, abortions, birth complications, etc.

Materials and Methods: The study included 100 patients suffering from exacerbated chronic salpingo-oophoritis and its combination with bacterial vaginosis. In the study, all the patients were randomly divided into five groups, with 20 patients each. The patients were treated in the prescribed regimens and doses, according to the standards of specialized medical care. An immunomodulator immunomax and an antioxidant hypoxene were chosen as additional treatment options. Clinical and laboratory parameters were measured in all the patients before and after the treatment. The effectiveness of the treatment was evaluated 10-14 days later. In 18 people, the procedure was repeated after 2-3 months.

Results and Discussion: It was found that the standard therapy to treat exacerbated chronic salpingo-oophoritis reduced inflammatory manifestations after 10-14 days; however, the risk of complications and relapse of the disease remained. Immunomax provided satisfactory second-order normalization of the immunological and metabolic parameters, ultimate normalization of pro-inflammatory parameters and absolutely no positive effect on the clinical parameters in patients with chronic salpingo-oophoritis in the acute stage, when compared with the standard treatment. A complex therapy of salpingo-oophoritis with bacterial vaginosis by means of immunomax and hypoxene aimed to normalize most clinical and laboratory parameters was absolutely positive; a moderate level of parameters was revealed only in cellular-humoral immunity.

Conclusion: After 10-14 days, the standard treatment of patients resulted in normalization of the pro-inflammatory and immunological parameters, rather than the clinical and metabolic parameters. The administration of immunomax contributed to the correction of metabolic, immunological and pro-inflammatory markers, and the complex administration of an immunomodulator with an antioxidant favorably affected all the laboratory parameters.

[Autoimmune markers for non-invasive diagnosis of endometriosis in women]

Endometriosis is a common estrogen-dependent chronic disease in women of reproductive age; it is associated with dysregulation of the immune response, local inflammation, and increased formation of autoantibodies. The aim of the study was to investigate the profile of autoantibodies in women with endometriosis and to evaluate their diagnostic value using new modifications of enzyme immunoassay. In women with endometriosis of stage III-IV (n=39), a wide spectrum of autoantibodies was detected, mainly of class G, including antibodies to endometrial antigens (tropomyosin 3, tropomodulin 3), the enzyme α-enolase, steroid (estradiol, progesterone) and gonadotropic hormones. At the same time, the frequency of detection of IgG antibodies to tropomyosin 3, α-enolase, estradiol and human chorionic gonadotropin and their levels in patients with endometriosis were higher than in healthy women (n=26) (p<0.05). IgG-antibodies to tropomyosin 3, α-enolase and estradiol were characterized by higher diagnostic value for endometriosis. The diagnostic value was significantly increased when these antibodies were combined: the AUC reached 0.875 [0.772-0.978] (p<0.0001), the sensitivity and specificity were 83.3% each. Thus, autoantibodies to tropomyosin 3, α-enolase, and estradiol are promising for inclusion in the panel of biomarkers for non-invasive diagnosis of endometriosis.

Toll-Like Receptor 2 Expression as a New Hallmark of Advanced Endometriosis

Recent evidence suggests that immunological aspects play a pivotal role in this disorder. Toll-like receptor 2 (TLR2) is crucial in recognizing microbial infections and mediating innate immune response. The objective of our study was to rate with flow cytometry the levels of several subsets of dendritic cells, monocytes, and basic peripheral blood lymphocytes expressing TLR2, aiming at the determination of a possible correlation between the expression of TLR2 and the clinical outcomes of endometriosis in 40 patients and 40 age-matched healthy women. Our study showed the importance of TLR2 expression, mainly on myeloid dendritic cells (mDCs) and B cells in patients with endometriosis. Both mDCs BDCA1+CD19-TLR2+ and B lymphocytes CD19+TLR-2+ proved useful in the differentiation of affected individuals with stages 3–4 of the disease (area under the receiver operating characteristic curve /AUC/ = 0.96, p < 0.0001 for mDCs; AUC = 0.78, p = 0.0001 for B lymphocytes), and those presenting adhesion (AUC = 0.92, p < 0.0001 for mDCs; AUC = 0.82, p < 0.0001 for B lymphocytes) or infertility (AUC = 0.83, p < 0.0001 for mDCs; AUC = 0.73, p = 0.006 for B lymphocytes). Our findings suggest that the levels of TLR2-expressing cells, particularly mDCs and B lymphocytes, may be an effective biomarker of endometriosis, because the disease currently lacks clinically useful noninvasive biomarkers enabling early and cost-effective diagnosis.

Granzyme B levels and granzyme B polymorphisms in peripheral blood of patients with endometriosis: a preliminary study

The chronic course of endometriosis suggests that the immune system may play a role in its aetiology. There may be resistance to cell lysis, as well as an immune defect underlying endometriosis. Granzyme B is a serine protease that is secreted by Natural Killer (NK) cells and cytotoxic T lymphocytes during a cellular immune response and can induce apoptosis. The aim of this study was to evaluate the relationship between both Granzyme B levels and Granzyme B gene polymorphisms in endometriosis patients. Women between the ages of 20 - 45 were included in the study. The patients were divided into two groups: those diagnosed with endometriosis and those who had not been diagnosed with endometriosis. In the blood samples, Granzyme B gene polymorphisms and serum levels of Granzyme B were studied. There was no difference between the groups in terms of median Granzyme B levels and the presence of AA, AG, and GG genotypes. There was a difference in median granzyme levels for the control group; the GG genotype was found at a lower frequency. The immune defect within endometriosis-related immune cells may not be exclusively due to Granzyme B. Other mediators that are secreted from immune cells may have additive effects.IMPACT STATEMENTWhat is already known on this subject? NK cells are cytotoxic and inhibit the implantation of autologous endometrial cells that are spilled into the peritoneum by retrograde menstruation. Thus, a reduction in NK cell activity may facilitate the progression of endometriosis. The literature review reveals that there are studies suggesting that NK cell activity may be insufficient in endometriosis. Granzyme B is a serine protease that is secreted by NK cells and cytotoxic T lymphocytes during a cellular immune response.What do the results of this study add? Granzyme B is one of the cytotoxic granules in NK and cytotoxic T lymphocyte cells and its genetic polymorphisms were tested in endometriosis. We found that median Granzyme B levels were significantly different in patients with the GG genotype in the control group, compared to those with the AA and AG genotype. However, this difference was not detected between the control and endometriosis groups.What are the implications of these findings for clinical practice and/or further research? Our results contribute to uncovering the pathogenesis of endometriosis since there are no previous studies in the literature regarding this topic. Although we did not find a difference, our results will inform further studies made on this topic. Studies with different molecules and an increased number of patients are needed. The immune defect of endometriosis may not be due exclusively to Granzyme B. Other mediators that are secreted from immune cells may have mutual effects and interactions.

Role of Regulatory T Cells in Regulating Fetal-Maternal Immune Tolerance in Healthy Pregnancies and Reproductive Diseases

Regulatory T cells (Tregs) are a specialized subset of T lymphocytes that function as suppressive immune cells and inhibit various elements of immune response in vitro and in vivo. While there are constraints on the number or function of Tregs which can be exploited to evoke an effective anti-tumor response, sufficient expansion of Tregs is essential for successful organ transplantation and for promoting tolerance of self and foreign antigens. The immune-suppressive property of Tregs equips this T lymphocyte subpopulation with a pivotal role in the establishment and maintenance of maternal tolerance to fetal alloantigens, which is necessary for successful pregnancy. Elevation in the level of pregnancy-related hormones including estrogen, progesterone and human chorionic gonadotropin promotes the recruitment and expansion of Tregs, directly implicating these cells in the regulation of fetal-maternal immune tolerance. Current studies have provided evidence that a defect in the number or function of Tregs contributes to the etiology of several reproductive diseases, such as recurrent spontaneous abortion, endometriosis, and pre-eclampsia. In this review, we provide insight into the underlying mechanism through which Tregs contribute to pregnancy-related immune tolerance and demonstrate the association between deficiencies in Tregs and the development of reproductive diseases.

Evaluation of complement system proteins C3a, C5a and C6 in patients of endometriosis

BACKGROUND

Endometriosis is a disease that shows auto-immune and chronic characteristics, suggesting a role for proteins mediating immune interactions in its pathophysiology. The aim was to evaluate C3a and C5a for their role in inflammatory responses and C6 as the down-stream interactor following our previous findings on C5 mRNA expression changes in endometriosis [1].

METHODS

Sera from 71 endometriosis patients and 77 women without endometriosis were taken. While the samples were taken only once from the controls, the patient samples were taken before, in 1st and in 7th days after laparoscopy. Levels of complement proteins C3a, C5a and C6 were measured with ELISA assays. MPV (Mean Platelet Volume), CRP (C-Reactive Protein) and NLR (Neutrophil-to-Leukocyte Ratio) were also analyzed from the retrospective data.

RESULTS

C6 levels of early-stage patients at postoperative 1st day were significantly higher than controls. Patients with high MPV measurements had significantly higher C3a (p < 0.0001) and C6 (p < 0.05) levels than controls at all times of measurement.

CONCLUSIONS

C6, an integral component of the membrane attack complex (MAC), could play a role at early disease-stage. The changes in levels of complement proteins and their relation to high MPV levels suggest a broader area of interplay for immune interactors in endometriosis. Although a bigger and longitudinal study design is needed to obtain more accurate results to evaluate these proteins as potential biomarkers, an important role of complement system within the pathophysiology of endometriosis is apparent.

Estrogen Receptors and Endometriosis

Endometriosis is a frequent and chronic inflammatory disease with impacts on reproduction, health and quality of life. This disorder is highly estrogen-dependent and the purpose of hormonal treatments is to decrease the endogenous ovarian production of estrogens. High estrogen production is a consistently observed endocrine feature of endometriosis. mRNA and protein levels of estrogen receptors (ER) are different between a normal healthy endometrium and ectopic/eutopic endometrial lesions: endometriotic stromal cells express extraordinarily higher ERβ and significantly lower ERα levels compared with endometrial stromal cells. Aberrant epigenetic regulation such as DNA methylation in endometriotic cells is associated with the pathogenesis and development of endometriosis. Although there is a large body of data regarding ERs in endometriosis, our understanding of the roles of ERα and ERβ in the pathogenesis of endometriosis remains incomplete. The goal of this review is to provide an overview of the links between endometriosis, ERs and the recent advances of treatment strategies based on ERs modulation. We will also attempt to summarize the current understanding of the molecular and cellular mechanisms of action of ERs and how this could pave the way to new therapeutic strategies.

Regulatory T cells isolated from endometriotic peritoneal fluid express a different number of Toll-like receptors

Objective

To analyze and compare the expression of Toll-like receptors by regulatory T cells present in the peritoneal fluid of patients with and without endometriosis.

Methods

Regulatory T cells were isolated from peritoneal fluid of women with and without endometriosis, collected during surgery, and mRNA was extracted for analysis of Toll-like receptors expression by reverse-transcriptase polymerase chain reaction.

Results

Patients with endometriosis presented regulatory T cells expressing a larger number and variety of Toll-like receptors when compared to regulatory T cells from patients in the Control Group. Toll-like receptor-1 and Toll-like receptor-2 in regulatory T cells were expressed in both groups. All other expressed Toll-like receptors types were only found in regulatory T cells from the Endometriosis Group.

Conclusion

Patients with endometriosis had peritoneal regulatory T cells expressing various Toll-like receptors types.

Microbiome Profile of Deep Endometriosis Patients: Comparison of Vaginal Fluid, Endometrium and Lesion

This work aimed to identify and compare the bacterial patterns present in endometriotic lesions, eutopic endometrium and vaginal fluid from endometriosis patients with those found in the vaginal fluid and eutopic endometrium of control patients. Vaginal fluid, eutopic endometrium and endometriotic lesions were collected. DNA was extracted and the samples were analyzed to identify microbiome by high-throughput DNA sequencing of the 16S rRNA marker gene. Amplicon sequencing from vaginal fluid, eutopic endometrium and endometriotic lesion resulted in similar profiles of microorganisms, composed most abundantly by the genus Lactobacillus, Gardnerella, Streptococcus and Prevotella. No significant differences were found in the diversity analysis of microbiome profiles between control and endometriotic patients; however deep endometriotic lesions seems to present different bacterial composition, less predominant of Lactobacillus and with more abundant Alishewanella, Enterococcus and Pseudomonas.

Autonomic nervous system and inflammation interaction in endometriosis-associated pain

Endometriosis is a chronic inflammatory disease. Pain is the most common symptom in endometriosis. Endometriosis-associated pain is caused by inflammation, and is related to aberrant innervation. Although the specific mechanism between endometriosis-associated pain and the interaction of aberrant innervation and inflammation remains unclear, many studies have confirmed certain correlations between them. In addition, we found that some chronic inflammatory autoimmune diseases (AIDs) such as inflammatory bowel disease (IBD) and rheumatoid arthritis (RA) share similar characteristics: the changes in dysregulation of inflammatory factors as well as the function and innervation of the autonomic nervous system (ANS). The mechanisms underlying the interaction between the ANS and inflammation have provided new advances among these disorders. Therefore, the purpose of this review is to compare the changes in inflammation and ANS in endometriosis, IBD, and RA; and to explore the role and possible mechanism of sympathetic and parasympathetic nerves in endometriosis-associated inflammation by referring to IBD and RA studies to provide some reference for further endometriosis research and treatment.

Reduction of myeloid derived suppressor cells by inhibiting Notch pathway prevents the progression of endometriosis in mice model

Growing evidence suggested that immune dysregulation is one of the crucial drivers to the development of endometriosis (EMS). Myeloid derived suppressor cells (MDSCs) represent a heterogeneous subset of immature myeloid cells, and have been reported to promote the onset and progression of EMS. Notch signaling pathway played a major role in immunological reactions. Studies have found Notch signaling pathway could regulate MDSCs. However, how the biological effects of Notch signaling pathway on MDSCs may work in EMS is still unknown. In our study, we first built an endometriosis induced mice model. Then we treated mice with DAPT, a Notch signaling pathway inhibitor, or saline. We found that the DAPT could prevent the progression of EMS. The ADAM17, Notch1, Jagged1 and Hes1 were overexpressed in EMS mice, however, when mice were treated with DAPT, the overexpression was reduced. Meanwhile, we found a lower level of MDSCs in the DAPT treated EMS mice as compared to EMS mice without DAPT, accompanied by an increase of T helper (TH) 17 cells and a decrease of regulatory T cells (Tregs). We also investigated the reactive oxygen species (ROS) in peritoneal and endometriotic cells. Our results showed that ROS level decreased in both peritoneal and endometriotic cells in the study group treated with DAPT. Overall, our study indicates for the first time that blockage of Notch signaling could lessen MDSCs and ROS, and therefore preventing the development of endometriosis.

Endometriosis - a decade later - still an enigmatic disease. What is the new in the diagnosis and treatment?

Endometriosis is a common disease in women of reproduction age. It causes pain and difficulty in getting pregnant. However the exact causes of infertility associated with endometriosis still remain controversial. The treatment of endometriosis consists of medical treatment of pain as well as medical and surgical treatment of infertility caused by endometriosis and assisted reproduction techniques. Since the treatment of endometriosis is often connected with diminishing ovarian reserve, the techniques for ovarian tissue preservation and oocyte and embryo freezing are used to maintain the ability for childbearing.

Mass cytometry analysis reveals a distinct immune environment in peritoneal fluid in endometriosis: a characterisation study

BACKGROUND

Endometriosis is a gynaecological condition characterised by immune cell infiltration and distinct inflammatory signatures found in the peritoneal cavity. In this study, we aim to characterise the immune microenvironment in samples isolated from the peritoneal cavity in patients with endometriosis.

METHODS

We applied mass cytometry (CyTOF), a recently developed multiparameter single-cell technique, in order to characterise and quantify the immune cells found in peritoneal fluid and peripheral blood from endometriosis and control patients.

RESULTS

Our results demonstrate the presence of more than 40 different distinct immune cell types within the peritoneal cavity. This suggests that there is a complex and highly heterogeneous inflammatory microenvironment underpinning the pathology of endometriosis. Stratification by clinical disease stages reveals a dynamic spectrum of cell signatures suggesting that adaptations in the inflammatory system occur due to the severity of the disease. Notably, among the inflammatory microenvironment in peritoneal fluid (PF), the presence of CD69⁺ T cell subsets is increased in endometriosis when compared to control patient samples. On these CD69⁺ cells, the expression of markers associated with T cell function are reduced in PF samples compared to blood. Comparisons between CD69⁺ and CD69^- populations reveal distinct phenotypes across peritoneal T cell lineages. Taken together, our results suggest that both the innate and the adaptive immune system play roles in endometriosis.

CONCLUSIONS

This study provides a systematic characterisation of the specific immune environment in the peritoneal cavity and identifies cell immune signatures associated with endometriosis. Overall, our results provide novel insights into the specific cell phenotypes governing inflammation in patients with endometriosis. This prospective study offers a useful resource for understanding disease pathology and opportunities for identifying therapeutic targets.

Environmental Endocrine Disruptors and Endometriosis

As a consequence of industrialization, thousands of man-made chemicals have been developed with few undergoing rigorous safety assessment prior to commercial use. Ubiquitous exposure to these compounds, many of which act as endocrine-disrupting chemicals (EDCs), has been suggested to be one factor in the increasing incidence of numerous diseases, including endometriosis. Endometriosis, the presence of endometrial glands and stroma outside the uterus, is a common disorder of reproductive-age women. Although a number of population-based studies have suggested that exposure to environmental EDCs may affect a woman's risk of developing this disease, results of epidemiology assessments are often equivocal. The development of endometriosis is, however, a process occurring over time; thus, a single assessment of toxicant body burden cannot definitively be linked to causation of disease. For this reason, numerous investigators have utilized a variety of rodent models to examine the impact of specific EDCs on the development of experimental endometriosis. These studies identified multiple chemicals capable of influencing physiologic processes necessary for the establishment and/or survival of ectopic tissues in rodents, suggesting that these compounds may also be of concern for women. Importantly, these models serve as useful tools to explore strategies that may prevent adverse outcomes following EDC exposure.

Recent advances in mammalian reproductive biology

Reproductive biology is a uniquely important topic since it is about germ cells, which are central for transmitting genetic information from generation to generation. In this review, we discuss recent advances in mammalian germ cell development, including preimplantation development, fetal germ cell development and postnatal development of oocytes and sperm. We also discuss the etiologies of female and male infertility and describe the emerging technologies for studying reproductive biology such as gene editing and single-cell technologies.

Differential Expression of KRAS and SIRT1 in Ovarian Cancers with and Without Endometriosis

Accumulating research shows that ovarian cancer progression can be influenced by both gene mutations and endometriosis. However, the exact mechanism at hand is poorly understood. In the current study, we explored the expression of KRAS and SIRT1, two genes previously identified as altered in endometriosis and ovarian cancer. Human endometrial samples were obtained from regularly cycling women with endometriosis, ovarian cancer, and endometriosis-associated ovarian cancer between 18 and 50 of age undergoing hysterectomy, and immunohistochemical analyses were performed. The cytoplasmic expression of KRAS was low in eutopic endometrium from women without endometriosis or ovarian cancer; however, it was elevated in those who have been diagnosed with endometriosis, as well as ovarian cancer with or without the presence of endometriosis. Nuclear and cytoplasmic SIRT1 expression was also low within endometrium without either disease. However, nuclear SIRT1 expression was increased in those with endometriosis and ovarian cancer associated with endometriosis. Nuclear but not the cytoplasmic expression of SIRT1 correlated with KRAS expression in ovarian cancers associated with endometriosis. These results suggest roles of KRAS and SIRT1 in endometriosis and endometriosis-associated ovarian cancer. Cytoplasmic KRAS expression proves to be a key biomarker in both diseases, while nuclear SIRT1 may be a new biomarker specific to those with endometriosis and those with both endometriosis and ovarian cancer. Further research of these genes could aid in determining the pathogenesis of both diseases and help in clarifying the development of endometriosis-associated ovarian cancer.

Immune-metabolic genesis of pathological processes

This article deals with metabolic-immune processes at rest and under stress conditions, which, in turn, results in the development of immune-dependent and immune-associated disorders. The article analyzes study results and conclusions of various literature sources and experimental data in healthy individuals and patients suffering from non-specific inflammatory lung diseases; purulent-inflammatory diseases and their combinations, primary and secondary progressive multiple sclerosis in the acute stage and remission. Research studies investigated the impact of the type, stage, combination of diseases on the parameters of the immunologic and metabolic statuses, as well as their correlations. The authors also analyzed metabolic effects of immunomodulators. Based on the analysis of the literature and own clinical and experimental data, the authors identified the ability of metabolic factors to regulate immunological processes. A correlative analysis of examination results of the patients with various diseases helped detect the unity of the immune-metabolic mechanisms of pathology. The data on the therapeutic effect of various modulators through differentiated biochemical chains and vice versa – the metabolic effect through immunological mechanisms –were analyzed in the study. Thus, one can testify that there is the phenomenon of a mediated effect of some immunocorrectors on the reactivity through metabolic chains. The fact that a number of modulators and metabolics can simultaneously affect the biochemical and immunological parameters of patients proved the above phenomenon. There was revealed a significant correlation interaction of the immune-metabolic parameters with various types of purulent-inflammatory diseases, which proves the formation of a single mechanism of pathology.

Infertility in women with systemic autoimmune diseases

Infertility consists by definition in" failure to achieve a clinical pregnancy after 12 months or more of regular unprotected intercourse" while the term subfertility means a delay to achieve pregnancy. Several factors can contribute to infertility or subfertility in patients with systemic autoimmune diseases. The association of systemic autoimmune conditions with endometriosis, celiac disease and thyroid autoimmunity that are well known causes of infertility and/or subfertility need to be taken in consideration when difficulties in the onset of pregnancy is reported. The majority of the used antirheumatic drugs do not interfere with fertility. However, the use of cyclophosphamide, limited to severe disease, can provoke premature ovarian failure; to preserve fertility a preventive treatment is available. Nonsteroidal anti-inflammatory drugs can cause temporary infertility and corticosteroids are associated to a prolonged time to pregnancy in some rheumatic diseases. Data on the association of antiphospholipid antibodies (aPL) with infertility are still debated but in general an increased rate of aPL is described patients undergoing medically assisted reproductive techniques. In systemic lupus erythematosus aPL and other autoantibodies (i.e. anti-oocytes) can contribute to the infertility of some patients. Subfertility, rather than infertility, is observed in patients with rheumatoid arthritis; the particular physical conditions of these women can also account for this. Physicians should not forget the patients' age, that is mandatory in order to preserve their chance to have children.

Impaired Expression of Ectonucleotidases in Ectopic and Eutopic Endometrial Tissue Is in Favor of ATP Accumulation in the Tissue Microenvironment in Endometriosis

Endometriosis is a prevalent disease defined by the presence of endometrial tissue outside the uterus. Adenosine triphosphate (ATP), as a proinflammatory molecule, promotes and helps maintain the inflammatory state of endometriosis. Moreover, ATP has a direct influence on the two main symptoms of endometriosis: infertility and pain. Purinergic signaling, the group of biological responses to extracellular nucleotides such as ATP and nucleosides such as adenosine, is involved in the biology of reproduction and is impaired in pathologies with an inflammatory component such as endometriosis. We have previously demonstrated that ectonucleotidases, the enzymes regulating extracellular ATP levels, are active in non-pathological endometria, with hormone-dependent changes in expression throughout the cycle. In the present study we have focused on the expression of ectonucleotidases by means of immunohistochemistry and in situ activity in eutopic and ectopic endometrial tissue of women with endometriosis, and we compared the results with endometria of women without the disease. We have demonstrated that the axis CD39-CD73 is altered in endometriosis, with loss of CD39 and CD73 expression in deep infiltrating endometriosis, the most severe, and most recurring, endometriosis subtype. Our results indicate that this altered expression of ectonucleotidases in endometriosis boosts ATP accumulation in the tissue microenvironment. An important finding is the identification of the nucleotide pyrophophatase/phosphodiesterase 3 (NPP3) as a new histopathological marker of the disease since we have demonstrated its expression in the stroma only in endometriosis, in both eutopic and ectopic tissue. Therefore, targeting the proteins directly involved in ATP breakdown could be an appropriate approach to consider in the treatment of endometriosis.

CD4+/CD8+ mucosa-associated invariant T cells foster the development of endometriosis: a pilot study

BACKGROUND

Immune dysregulation is one of the mechanisms to promote endometriosis (EMS). Various T cell subpopulations have been reported to play different roles in the development of EMS. The mucosa-associated invariant T cell (MAIT) is an important T cell subset in the pathogenesis of various autoimmune diseases. Evidence has indicated that there are three functionally distinct MAIT subsets: CD4+, CD8+ and CD4/CD8-/- (double negative, DN) MAIT cells. Till now, the associations between endometriosis and MAIT have not been studied. Our research investigates different MAIT subpopulations in peripheral blood (PB) and peritoneal fluid (PF) from EMS patients.

METHODS

Thirty-two EMS patients and eighteen controls were included. PB and PF were collected. Tests of cytokines in plasma and PF were performed by ELISA kit. Characterisations of MAIT were done by flow cytometry. MAIT cells have been defined as CD3 + CD161 + Vα7.2+ cells. Based on CD4 and CD8 expression, they were divided into CD8⁺MAIT, CD4⁺MAIT and DN MAIT.

RESULTS

Enrichments of MAIT cells, especially CD4 and CD8 MAIT subsets were found. Moreover, CD8 MAIT cells had a high activation in the EMS group. EMS patients produced higher level of IL-8/12/17 as compared to these from controls. On the contrary, control patients exhibited an impressive upregulation of DN MAIT cells, however, these DN MAIT cells from controls showed a higher expression of PD-1. Lastly, we performed the relevance analysis, and discovered that the accumulation of PB MAIT cells positively correlated with an elevated level of serum CA125 production in EMS group.

CONCLUSION

These results suggest that different MAIT subsets play distinct roles in the progression of endometriosis.

NK Cells as Potential Targets for Immunotherapy in Endometriosis

Endometriosis is a common gynecological disease defined by the presence of endometrial-like tissue outside the uterus, most frequently on the pelvic viscera and ovaries, which is associated with pelvic pains and infertility. It is an inflammatory disorder with some features of autoimmunity. It is accepted that ectopic endometriotic tissue originates from endometrial cells exfoliated during menstruation and disseminating into the peritoneum by retrograde menstrual blood flow. It is assumed that the survival of endometriotic cells in the peritoneal cavity may be partially due to their abrogated elimination by natural killer (NK) cells. The decrease of NK cell cytotoxic activity in endometriosis is associated with an increased expression of some inhibitory NK cell receptors. It may be also related to the expression of human leukocyte antigen G (HLA-G), a ligand for inhibitory leukocyte immunoglobulin-like receptor subfamily B member 1 (LILRB1) receptors. The downregulated cytotoxic activity of NK cells may be due to inhibitory cytokines present in the peritoneal milieu of patients with endometriosis. The role of NK cell receptors and their ligands in endometriosis is also confirmed by genetic association studies. Thus, endometriosis may be a subject of immunotherapy by blocking NK cell negative control checkpoints including inhibitory NK cell receptors. Immunotherapies with genetically modified NK cells also cannot be excluded.

Endometriosis Pathoetiology and Pathophysiology: Roles of Vitamin A, Estrogen, Immunity, Adipocytes, Gut Microbiome and Melatonergic Pathway on Mitochondria Regulation

Endometriosis is a common, often painful, condition that has significant implications for a woman’s fertility. Classically, endometriosis has been conceptualized as a local estrogen-mediated uterine condition driven by retrograde menstruation. However, recent work suggests that endometriosis may be a systemic condition modulated, if not driven, by prenatal processes. Although a diverse array of factors have been associated with endometriosis pathophysiology, recent data indicate that the low body mass index and decreased adipogenesis may be indicative of an early developmental etiology with alterations in metabolic function crucial to endometriosis pathoetiology.

The present article reviews the data on the pathoetiology and pathophysiology of endometriosis, suggesting key roles for alterations in mitochondria functioning across a number of cell types and body systems, including the immune system and gut microbiome. These changes are importantly regulated by decreases in vitamin A and its retinoic acid metabolites as well as increases in mitochondria estrogen receptor-beta and the N-acetylserotonin/melatonin ratio across development. This has treatment and future research implications for this still poorly managed condition, as well as for the association of endometriosis with a number of cancers.

Human endometriotic lesion expression of the miR-144-3p/miR-451a cluster, its correlation with markers of cell survival and origin of lesion content

Endometriosis is an inflammatory condition in which endometrial tissue grows in ectopic locations. Survival and growth of these ectopic lesions is associated with pain and infertility. MicroRNAs (miRNAs) have been postulated to play a role in the pathophysiology of the disease and we have previously demonstrated expression of miR-451 in human endometriotic lesion tissue. Here we report elevated expression of the miR-144-3p/miR-451a cluster in human endometriotic lesion tissue. Use of an endometriotic epithelial cell line (12Z) in which the miRNA processing enzyme, DROSHA, was knocked down resulted in an enrichment in the primary (pri) form of miR-144-3p but not that of pri-miR-451a. Using an experimental mouse model of endometriosis in which ectopic endometriotic lesions were deficient for both of these miRNAs revealed that miR-451a, but not miR-144-3p may be derived from exogenous sources such as the circulation/erythrocytes. Together, these data suggest that the miR-144-3p/miR-451a cluster is expressed in human endometriotic lesion tissue, the level of expression correlates with survival status of the lesion tissue and that miR-451a, but not miR-144-3p may be derived from exogenous sources such as erythrocytes.

Comprehensive immune complexome analysis detects disease-specific immune complex antigens in seminal plasma and follicular fluids derived from infertile men and women

BACKGROUND

Autoimmune reactions and subsequent inflammation may underlie spermatogenic dysfunction and endometriosis-related infertility. The aim of this study is to identify disease-specific antigens in immune complexes (ICs) in seminal plasma (SP) and in follicular fluid (FF).

METHODS

Immune complexome analysis, in which nano-liquid chromatography-tandem mass spectrometry is employed to comprehensively identify antigens incorporated into ICs in biological fluids, was performed for specimens collected from infertile couples undergoing assisted reproduction. Forty-two male patients consisting of subjects with oligozoospermia (n = 6), asthenozoospermia (n = 8), and normal semen analysis (n = 28). Fifty-eight female patients consisting of subjects with ovarian endometriosis (n = 10) and control women without disease (n = 48).

RESULTS

Four disease-specific antigens were identified in subjects with oligozoospermia, while five disease-specific antigens were detected in subjects with asthenozoospermia, some of which are involved in sprematogenesis. Eight antigens were detected only in subjects with endometriosis.

CONCLUSION

Functional characteristics of disease-specific antigens were found to correspond to the pathogenesis of male and female infertility. The formation of ICs may contribute to spermatogenic dysfunction and endometriosis-related infertility via loss of function of the related proteins. Immune complexome analysis is expected to be a valuable tool for the investigation of novel diagnostic methods and treatment strategies for infertility.

CCR5/CCR5 ligand-induced myeloid-derived suppressor cells are related to the progression of endometriosis

RESEARCH QUESTION

Immunological disorders have been reported to promote the progression of endometriosis. Several recent studies have shown that myeloid-derived suppressor cells (MDSC) drive the progression of endometriosis. The aim of this case-control study was to test whether CCR5 and its ligands drive MDSC accumulation and play a role in the progression of endometriosis.

DESIGN

Thirty-six endometriosis patients and 20 controls were recruited. All subjects underwent laparoscopy. An ELISA kit was used to define CCR5 ligands in plasma and peritoneal fluid from endometriosis patients; flow cytometry was then used to characterize CCR5⁺MDSC in peripheral blood and peritoneal fluid.

RESULTS

Data showed that endometriosis patients displayed a significantly higher production of plasma CCL3 (P = 0.046) and peritoneal fluid CCL3/5 (P = 0.042/0.036) compared with those from the uterine leiomyoma group. Furthermore, the concentrations of peritoneal fluid CCL5 were elevated in late stage patients compared with those from the uterine leiomyoma group. Accumulation of blood CCR5⁺Mo-MDSC was detected in endometriosis patients compared with those from both the ovarian dermoid cysts and uterine leiomyoma groups. Endometriosis patients also showed an elevation of CCR5⁺MDSC and CCR5⁺Mo-MDSC in peritoneal fluid samples compared with uterine leiomyoma samples. It was also found that enrichment of CCR5⁺MDSC (r = 0.6807; P < 0.0001) and CCR5⁺Mo-MDSC (r = 0.6893; P < 0.0001) were correlated with enhanced production of CCL5 in peritoneal fluid from endometriosis patients.

CONCLUSIONS

This study showed that CCR5 and its ligands could drive the progression of endometriosis by enhancing the accumulation of MDSC. These findings might produce a promising treatment that targets CCR5⁺MDSC for endometriosis patients.

Effect of Maternal Advanced Endometriosis on Risk of Congenital Malformations for Infants Born After in vitro Fertilization and Frozen-Thawed Embryo Transfer: Analysis of 28,600 Newborns

Background: Endometriosis is one of the most challenging diseases for doctors helping infertile women conceive, which has become a common method to help maternal endometriosis-associated infertility. Women with advanced endometriosis possess a higher risk of several adverse outcomes both during pregnancy and at the time of delivery. Whether endometriosis gives rise to a higher occurrence of congenital abnormalities in infants via in vitro fertilization and frozen-thawed embryo transfer (IVF-ET) remains unknown. Methods: Data collected on 22,865 women undergoing IVF using a freeze-all strategy from 2007 to 2017 were analyzed to estimate the rate of congenital malformations. We used an adjusted OR to compare the fertility outcomes of women with advanced endometriosis to the control group. Results: We studied 1,495 infants born from women with advanced endometriosis and 27,105 infants born from endometriosis-free women. There was a 1.557-fold risk that the infants with advanced maternal endometriosis would develop a congenital malformation (adjusted OR: 1.557, 95% CI: 1.03-2.35). Compared with singletons, twins were 1.957 times more likely to experience an adverse outcome (OR: 1.957, 95% CI: 1.561-2.455). When analyzing specific categories of birth defects, the proportion of circulatory system defects was higher than the other categories of birth defects in total (0.56%), followed by musculoskeletal system defects (0.15%). Conclusions: Maternal advanced endometriosis might increase the risk of congenital malformations for infants born after IVF-ET. The organ system most frequently affected by congenital malformations was the cardiovascular system, followed by the musculoskeletal system.