A possible mechanism of autoimmune-mediated infertility in women with endometriosis

Ovarian endometrioma increases the embryo aneuploid rate: an analysis of 7092 biopsied blastocysts from fertile monogenetic disease carriers

BACKGROUND

Endometriosis affects many reproductive aged patients with fertility decline and poor outcomes of assisted reproductive treatments, mainly by decreased ovarian reserve and lower fertilization and implantation rates. In recent decade, altered oocyte microenvironments and abnormal spindle organization have been reported to be critical to oocyte chromosomal segregation, organization and aneuploid formation. However, clinical evidences are still limited on whether endometriosis influences oocyte and embryo development. We aimed to figure out the impact of endometrioma on embryo aneuploid formation.

METHOD

This retrospective cohort study included 1,021 patients (7,092 biopsied embryos) from January 2012 to December 2020. Fertile patients without a history of miscarriage who underwent PGT-M treatment with aneuploid screening were included. Patients with ovarian endometrioma were defined as the study group, while patients without endometriosis were defined as the control group. All demographic, controlled ovarian stimulation treatment and aneuploid screening data were recorded and compared.

RESULTS

The incidence of endometrioma in our study population was 6.5%. There were 7,092 embryos biopsied in total, with 308 embryos in the study group and 6,784 embryos in the control groups. The demographic characteristics were comparable between the two groups except the basal FSH level (6.02 IU/L vs. 5.52 IU/L, p = 0.012). The euploid rate of the study group was significantly lower than that of the control group (52.6% vs. 61.8%, p = 0.012), while the oocyte maturation, fertilization, usable embryo and blastocyst formation rates were comparable. Adjusted for basal FSH level, starting stimulating gonadotropin dosage, total gonadotropin dosage and FSH level on hCG day, euploid rate was still negatively related to endometrioma status.

CONCLUSIONS

Endometrioma status disturbs oocyte and embryo development. For infertile patients with endometrioma who require assisted reproductive treatment, pre-treatment is necessary to improve treatment outcomes.

TRIAL REGISTRATION

Not applicable.

Endometriosis and inflammatory immune responses: Indian experience

Endometriosis is a public health disorder affecting ∼ 247 million women globally and ∼ 42 million women in India. Women with endometriosis suffer from dysmenorrhea, chronic pelvic pain, dyspareunia, dyschezia, fatigue, depression, and infertility leading to significant socioeconomic impact and morbidity. The etiology of endometriosis is not understood well even after 100 years of research. Currently, there is no permanent cure for endometriosis. The inflammatory immune response is one of the important features of etiopathogenesis of endometriosis and therefore understanding the inflammatory immune response would lead to a better understanding of this enigmatic disorder and may also lead to biomarker discovery for diagnosis of endometriosis. We investigated the autoimmune etiology of endometriosis in the Indian population. Using the proteomics approach, anti-endometrial antibodies (AEAs) were detected in Indian women with endometriosis [anti-endometrial antibodies - tropomyosin 3 (TPM3), stomatin-like protein2 (SLP-2), and tropomodulin 3 (TMOD3)]. The studies on AEAs provided a better understanding of autoimmune mechanisms in endometriosis. All three subtypes of endometriosis; superficial peritoneal, ovarian endometrioma, and deep infiltrating endometriosis were reported in Indian women. In this review, we discuss our experiences of the inflammatory immune response, autoimmunity, comorbidities, and clinical phenotypes in women with endometriosis in India.

Endometriosis with infertility: A comprehensive review on the role of immune deregulation and immunomodulation therapy

BACKGROUND

Endometriosis is a multifactorial pathology dependent on intrinsic and extrinsic factors, but the immune deregulation seems to play a pivotal role. In endometriosis-associated infertility, this could raise the benefit of immunomodulatory strategies to improve the results of ART. In this review, we will describe (1) sera and peritoneal fluid cytokines and immune markers; (2) autoantibodies; and (3) immunomodulatory treatments in endometriosis with infertility.

METHODS

The literature research was conducted in MEDLINE, Embase, and Cochrane Library with the following keywords: "endometriosis", "unexplained miscarriage", "implantation failure", "recurrent implantation failure » and « IVF-ICSI », « biomarkers of autoimmunity", "TNF-α", "TNF-α antagonists", "infliximab", "adalimumab", "etanercept", "immunomodulatory treatment", "steroids", "intralipids", "intravenous immunoglobulins", "G-CSF", "pentoxyfylline".

RESULTS

Several studies analyzed the levels of pro-inflammatory cytokines in sera and peritoneal fluid of endometriosis-associated infertility, in particular TNF-α. Various autoantibodies have been found in peritoneal fluid and sera of infertile endometriosis women even in the absence of clinically defined autoimmune disease, as antinuclear, anti-SSA, and antiphospholipid autoantibodies. In few uncontrolled studies, steroids and TNF-α antagonists could increase the pregnancy rates in endometriosis-associated infertility, but well-designed trials are lacking.

CONCLUSION

Endometriosis is characterized by increased levels of cytokines and autoantibodies. This suggests the role of inflammation and immune cell deregulation in infertility associated with endometriosis. The strategies of immunomodulation to regulate these immune deregulations are poorly studied, and well-designed studies are necessary.

Maternal alloimmune IgG causes anti-glomerular basement membrane disease in perinatal transgenic mice that express human laminin α5

Mammalian immune systems are not mature until well after birth. However, transfer of maternal IgG to the fetus and newborn usually provides immunoprotection from infectious diseases. IgG transfer occurs before birth in humans across the placenta and continues after birth across the intestine in many mammalian species, including rodents. Transfer, which is mediated by the neonatal IgG Fc receptor, occurs by transcytosis across placental syncytiotrophoblasts and intestinal epithelium. Although maternal IgG is generally beneficial, harmful maternal allo- and autoantibodies can also be transferred to the fetus/infant, resulting in serious disease. To test this we generated transgenic mice that widely express human laminin α5 in their basement membranes. When huLAMA5 transgenic males were crossed with wild-type females, there was a maternal anti-human laminin α5 immune response. Maternal IgG alloantibody crossed the yolk sac and post-natal intestine invivo and bound in bright, linear patterns to kidney glomerular basement membranes of transgenic fetuses/neonates but not those of wild-type siblings. By postnatal day 18, most transgenic mice were proteinuric, had glomerular C3 deposits and inflammatory cell infiltrates, thickened and split glomerular basement membranes, and podocyte foot process effacement. Thus, our novel model of perinatal anti-glomerular basement membrane disease may prove useful for studying pediatric glomerulopathies, formation of the fetomaternal interface, and maternal alloimmunization.

Synergistic effect of regulatory T cells and proinflammatory cytokines in angiogenesis in the endometriotic milieu

STUDY QUESTION

Do regulatory T cells (Tregs) contribute to angiogenesis in endometriosis?

SUMMARY ANSWER

High levels of CCL17 and CCL22 cause the recruitment of Tregs, upregulate the immunosuppression of Tregs and, in turn, may promote angiogenesis in endometrial cells in synergy with proinflammatory cytokines.

WHAT IS ALREADY KNOWN

The peritoneal fluid of patients with endometriosis has a higher percentage of Tregs than that of normal individuals; however, the regulatory role of Tregs in the disease remains unclear.

STUDY DESIGN, SIZE, DURATION

This study used primary human endometrial stromal cells (ESCs), monocytes (Mo), Tregs and human umbilical vein endothelial cells (HUVECs). All experiments were performed at least three times.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The migration of Tregs was evaluated by the transwell migration assay. The activation of extracellular signal-regulated kinase (ERK)1/2, c-Jun N-terminal kinase and p38 signaling pathways was examined using the In-Cell WesternTM (LI-COR®) western blot analysis system, as well as by traditional western blot analysis. Changes in the expression of CCL22, CCL17, transforming growth factor-beta 1 (TGF-β1), Interleukin (IL)-1β, tumor necrosis factor alpha (TNF-α), IL-8 and vascular endothelial growth factor (VEGF) in cell-culture supernatant were detected by ELISA. We analyzed the Tregs by multicolor flow cytometry to directly test the expression of CCR4, CD4, CD25, Foxp3, CTLA-4, CD39 and CD73.

MAIN RESULTS AND THE ROLE OF CHANCE

Our results showed that ESCs-Mo co-culture produced significantly higher levels of CCL22 and CCL17 than ESCs or Mo cultured alone, and that estradiol (E2) or progesterone (P) further promoted this upregulation, demonstrating stronger chemotaxis on Tregs. The co-culture of ESCs with Mo stimulated TGF-β1 secretion by Tregs, which could be inhibited by anti-CCL22 or/and anti-CCL17 neutralizing antibodies (Abs). The expression of CCR4 by Tregs was upregulated in ESCs-Mo co-culture, especially by treatment with E2 and/or P, and this effect could be abolished by anti-CCL22 and/or anti-CCL17-neutralizing Abs. The Treg-ESCs-Mo co-culture treated with E2 (10-8 mol/l) and P (10-8 mol/l) could enhance the immunosuppression of Tregs, as proved by the elevated expression of Foxp3, CTLA-4, CD39 and CD73 on Tregs. ESCs-Mo co-culture could significantly promote the secretion of IL-1β and TNF-α. TGF-β1 from Tregs could activate p38/ERK1/2 signaling pathways in ESCs, and IL-1β and TNF-α produced by ESCs-Mo co-culture had synergistic roles with TGF-β1. TGF-β1 and the proinflammatory cytokines IL-1β or TNF-α could synergistically promote IL-8 and VEGF expression in ESCs via the p38/ERK1/2 signaling pathways. The high levels of IL-8 and VEGF in the supernatant of ESCs stimulated the angiogenesis of HUVECs.

LARGE SCALE DATA

None.

LIMITATIONS, REASONS FOR CAUTION

This study was only performed in vitro using eutopic ESCs, instead of ectopic cells, from endometriosis patients. Therefore, it is necessary to do further experiments to determine whether Tregs promote angiogenesis in the endometriotic milieu in synergy with proinflammatory cytokines in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

Co-targeting Tregs and proinflammatory cytokines may be an effective treatment for endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by Ministry of Science and Technology of China 2015CB943300 to L.D.-J.; National Natural Science Foundation of China, item number 81200425 to  W.X.-Q.; National Natural Science Foundation of China, item number 81471548 to L.D.-J.; and The Research Fund for the Doctoral Program of Higher Education of China to W.X.-Q. (20110071120093). The authors have no conflicts of interest to declare.

Molecular aspects of development and regulation of endometriosis

Endometriosis is a common and painful condition affecting women of reproductive age. While the underlying pathophysiology is still largely unknown, much advancement has been made in understanding the progression of the disease. In recent years, a great deal of research has focused on non-invasive diagnostic tools, such as biomarkers, as well as identification of potential therapeutic targets. In this article, we will review the etiology and cellular mechanisms associated with endometriosis as well as the current diagnostic tools and therapies. We will then discuss the more recent genomic and proteomic studies and how these data may guide development of novel diagnostics and therapeutics. The current diagnostic tools are invasive and current therapies primarily treat the symptoms of endometriosis. Optimally, the advancement of "-omic" data will facilitate the development of non-invasive diagnostic biomarkers as well as therapeutics that target the pathophysiology of the disease and halt, or even reverse, progression. However, the amount of data generated by these types of studies is vast and bioinformatics analysis, such as we present here, will be critical to identification of appropriate targets for further study.

Fallopian tube: Its role in infertility and gynecological oncology

Disorders of the fallopian tube play a very important role in both infertility and gynaecological oncology. Tubal factor infertility is considered among the leading causes of female factor infertility. Many tubal disorders are related to infertility including congenital anomalies, acute and chronic inflammatory diseases, endometriosis and other pathologies that result in partial or total fallopian tube obstruction. In the field of gynaecological oncology, ovarian surface epithelial tumors remain one of the most fatal malignancies in women worldwide carrying the worst prognosis among female genital malignancies. For decades, the cell of origin of epithelial tumors has remained controversial and was largely believed to be surface ovarian epithelium. Recently several studies suggested that there is a major role of the fallopian tube in the development of ovarian surface epithelial tumors, mainly high grade serous carcinoma and other tumour types. In this article we review the role of the fallopian tube in both infertility and gynaecological oncology.

Infertility and pregnancy loss in euthyroid women with thyroid autoimmunity

Thyroid autoimmunity is the most prevalent autoimmune state that affects up to 5-20% of women during the age of fertility. Prevalence of thyroid autoimmunity is significantly higher among infertile women, especially when the cause of infertility is endometriosis or polycystic ovary syndrome. Presence of thyroid autoimmunity does not interfere with normal embryo implantation and have been observed comparable pregnancy rates after assisted reproduction techniques in patients with or without thyroid autoimmunity. Instead, the risk of early miscarriage is substantially raised with the presence of thyroid autoimmunity, even if there was a condition of euthyroidism before pregnancy. Furthermore the controlled ovarian hyperstimulation, used as preparation for assisted reproduction techniques, can severely impair thyroid function increasing circulating estrogen levels. Systematic screening for thyroid disorders in women with a female cause of infertility is controversial but might be important to detect thyroid autoimmunity before to use assisted reproduction techniques and to follow-up these parameters in these patients after controlled ovarian hyperstimulation and during pregnancy.

Kinetic and functional characterisation of the heparin-binding peptides from human transglutaminase 2

Transglutaminase 2 (TG2) is an autoantigen in celiac disease (CD) and it has multiple biologic functions including involvement in cell adhesion through interactions with integrins, fibronectin (FN), and heparan sulfate proteoglycans. We aimed to delineate the heparin-binding regions of human TG2 by studying binding kinetics of the predicted heparin-binding peptides using surface plasmon resonance method. In addition, we characterized immunogenicity of the TG2 peptides and their effect on cell adhesion. The high-affinity binding of human TG2 to the immobilized heparin was observed, and two TG2 peptides, P1 (amino acids 202-215) and P2 (261-274), were found to bind heparin. The amino acid sequences corresponding to the heparin-binding peptides were located close to each other on the surface of the TG2 molecule as part of the α-helical structures. The heparin-binding peptides displayed increased immunoreactivity against serum IgA of CD patients compared with other TG2 peptides. The cell adhesion reducing effect of the peptide P2 was revealed in Caco-2 intestinal epithelial cell attachment to the FN and FN-TG2 coated surfaces. We propose that TG2 amino acid sequences 202-215 and 261-274 could be involved in binding of TG2 to cell surface heparan sulfates. High immunoreactivity of the corresponding heparin-binding peptides of TG2 with CD patient's IgA supports the previously described role of anti-TG2 autoantibodies interfering with this interaction.

Induction of endometriosis alters the peripheral and endometrial regulatory T cell population in the non-human primate

BACKGROUND

Endometriosis is a gynecological condition that is characterized by extreme abdominal pain and also decreased fertility. Regulatory T cells (Tregs) have immunosuppressive activity critical for embryonic implantation and likewise the acceptance of tissue engraftment. Utilizing the induced non-human primate (Papio anubis) model of endometriosis, we hypothesize that endometriosis decreases the peripheral and endomet rial Treg profile, whereas ectopic lesions have increased Treg localization.

METHODS

Peripheral blood and endometrium were obtained throughout the menstrual cycle prior to and after induction of disease. Animals were randomly assigned to control (n = 7) or diseased (n = 16) treatment groups. Endometriosis was induced by i.p. injection of autologous menstrual tissue for 2 consecutive months during menses. Peripheral blood and endometrial tissue were collected at d9-11PO at 1, 3, 6, 9, 12 and 15 months post-induction of disease for fluorescence-activated cell sorting, quantitative RT-PCR and immunohistochemistry. Ectopic lesions were excised at 1 and 6 months post-inoculation and also harvested at necropsy (15 months) and processed for RNA of IHC. Identification of Tregs through analysis of FOXP3 expression was conducted utlilizing several methodologies. Differences were determined by non-parametric statistical analysis between all treatment groups and time points.

RESULTS

In control animals, the proportion of peripheral natural Tregs (nTregs) was reduced (P < 0.05) during the mid- and late secretory stages of the menstrual cycle compared with menses. The induction of disease decreased peripheral Treg expression at early time points (P < 0.05) and this remained low throughout the time course, compared with the pre-inoculatory level of an individual. FOXP3 gene expression and Treg populations were also decreased in the eutopic endometrium (P < 0.05) compared with control animals, whereas these parameters were increased in ectopic lesions (P < 0.05), compared with the eutopic endometrium.

CONCLUSIONS

Our data suggest that a reduction in peripheral Tregs may be a causative factor for endometriosis-associated infertility, while the increase in ectopic Treg expression may aid lesion development. Furthermore, endometriosis appears to disrupt Treg recruitment in both eutopic and ectopic endometrium.

Pathogenesis of infertility and recurrent pregnancy loss in thyroid autoimmunity

Thyroid autoimmunity is the most prevalent autoimmune state that affects up to 4% of women during the age of fertility. A growing body of clinical studies links thyroid autoimmunity as a cause of infertility and adverse pregnancy outcomes that includes miscarriage or preterm deliveries. Importantly, these adverse effects are persistent in euthyroid women. In the current review we elaborate on the pathogenesis that underlies infertility and increased pregnancy loss among women with autoimmune thyroid disease. Such mechanisms include thyroid autoantibodies that exert their effect in a TSH-dependent but also in a TSH-independent manner. The later includes quantitative and qualitative changes in the profile of endometrial T cells with reduced secretion of IL-4 and IL-10 along with hypersecretion of interferon-γ. Polyclonal B cells activation is 2-3 time more frequent in thyroid autoimmunity and is associated with increased titers of non-organ specific autoantibodies. Hyperactivity and Increased migration of cytotoxic natural killer cells that alter the immune and hormonal response of the uterus is up to 40% more common in women with thyroid autoimmunity. Lack of vitamin D was suggested as a predisposing factor to autoimmune diseases, and was shown to be reduced in patients with thyroid autoimmunity. In turn, its deficiency is also linked to infertility and pregnancy loss, suggesting a potential interplay with thyroid autoimmunity in the context of infertility. In addition, thyroid autoantibodies were also suggested to alter fertility by targeting zona pellucida, human chorionic gonadotropin receptors and other placental antigens.

Immunological aspects of endometriosis: an update

PROBLEM

Endometriosis is a very complex disease that profoundly affects the quality of life of many women.

METHOD OF STUDY

A review of the relationships between the female immune system and the occurrence and development of endometriosis.

RESULTS

Function and dysfunction of the female immune system plays important roles in the initiation and progression of the disease and its relation to infertility and cancer.

CONCLUSIONS

Owing to obvious associations between endometriosis and the immune system, future treatment strategies might be based on immunological concepts and methods.