Bacterial infection in endometriosis: a silver-lining for the development of new non-hormonal therapy?

The pathogenesis of endometriosis is a hotly debated topic, yet still cloaked in multiple layers of hypothetical theories. A recent report raises the possibility that bacterial infection, especially those of the genus Fusobacterium, may be the cause of endometriosis, at least in certain women. More importantly, the demonstration that treatment with broad-spectrum antibiotics significantly reduced the size of lesions in a mouse endometriosis model rekindles the hope for new non-hormonal treatments. The development of new therapies has been plagued by strings of unsuccessful clinical trials over the last two decades. Is this antibiotic therapy, a silver lining for the research and development of non-hormonal drugs for endometriosis?

Patterns of menstrual cycle, menstrual pain and medication usage in young women from high- and middle-income countries.

RESEARCH QUESTION: Do patterns of the menstrual cycle, menstrual pain and the use of medication for menstrual pain differ between young women from high-income countries (HIC) and middle-income countries (MIC)? DESIGN: A multinational, multicentre, cross-sectional study using pen-and-paper questionnaires was conducted between 2016 and 2021 to assess patterns of the menstrual cycle, menstrual pain and the use of medication for menstrual pain. Various parameters were evaluated to identify high-risk factors for severe menstrual pain in women from two HIC (n = 1550) and nine MIC (n = 7139). RESULTS: From a total of 9114 young women, 4920 medical students (HIC n = 696, MIC n = 4224) and 3769 nursing students (HIC n = 854, MIC n = 2915) were included in this study. Compared with those from HIC, a significantly higher proportion of medical and nursing students from MIC reported cyclic pain (83.9% and 86.8%, respectively) and acyclic pain (33.8% and 31.9%, respectively) (both P < 0.001). Multivariate regression analysis revealed that low body mass index and early onset of menarche were independent risk factors for severe cyclic/acyclic pain among women from HIC, and a family history of menstrual pain was a risk factor for severe cyclic/acyclic pain among women from HIC and MIC. CONCLUSIONS: Differential patterns of the menstrual cycle, menstrual pain and use of medication for menstrual pain were found between young women from HIC and MIC. A proper educational programme may be necessary for these women and healthcare providers to understand the consequences of intractable cyclic/acyclic pain, in order to facilitate early detection and timely management of menstrual pain and its negative consequences, such as endometriosis.

Is neonatal uterine bleeding responsible for early-onset endometriosis?

BACKGROUND: It has been hypothesized that the origin of early-onset endometriosis could be from endometrial mesenchymal stem cells (eMSCs) in neonatal uterine blood (NUB). There is no information on the possible mechanistic basis linking an association between NUB/neonatal endometrium and development of early-onset endometriosis. In this study we performed a series of experiments to clarify the mechanistic link between NUB and/or neonatal endometrium and development of early-onset endometriosis. METHODS: We retrospectively collected postmortem neonatal endometria (n = 15) and prospectively collected NUB (n = 18) of female babies for the analysis of different biological markers including eMSCs. Immunohistochemical analysis of neonatal endometria was performed to examine the expression patterns of ovarian steroid receptors (ER/PGR), decidualization (prolactin, IGFBP1), pre-decidualization (Glycodelin A, α-SMA), proliferation (Ki-67 index), vascularity (CD31 + cells), immunocompetent CD68+, CD45+, CD56 + cells and some putative markers of eMSCs. Cell transfer method and immunocytochemistry were used to investigate the eMSCs and/or endometrial cells in NUB. RESULTS: Immunohistochemical analysis of postmortem neonatal endometria revealed variable staining response to ER/PGR, decidual markers, and substantial proliferative and angiogenic activity. A moderate to strong immunoexpression of Glycodelin-A was found in both neonatal and adult endometria. The tissue infiltration of CD56+, CD45 + and CD68 + immunocompetent cells was significantly low in neonatal endometria than that in adult endometria (p = 0.0003, p < 0.0001, p = 0.034, respectively). No eMSCs or even endometrial cells were detected in NUB. However, a variable expression of some phenotypes of eMSCs (CD90/CD105) was found in neonatal endometria. CONCLUSIONS: Based on our serial experiments we did not find any supporting evidence for the role of NUB in early-onset endometriosis. Neonatal endometria showed variable expression of ovarian steroid receptors, decidualization, and a substantial amount of proliferative and angiogenic activity. As an alternative mechanism, a significantly less tissue accumulation of immunocompetent cells in neonatal endometria may explain the survival of ER + and PGR + cells should they make entry into the pelvis and consequent development of early endometriosis with the onset of ovarian function. Future study with large sample size and application of modified technological tools is warranted to test the NUB hypothesis and to clarify their biological or clinical significance. TRIAL REGISTRATION: not applicable.

Association between tissue stress reaction and ACE2/TMPRSS2 expression in endometria of reproductive aged women before and during Covid-19 pandemic.

BACKGROUND: A potential concern has been raised regarding fertility and reproductive outcome during the Covid-19 pandemic with growing stress and anxiety. However, information on the association between tissue stress reaction and expression profiles of SARS-CoV-2 viral entry proteins, ACE2 and TMPRSS2, in endometria collected from women before (pre-pandemic) and during the Covid-19 pandemic (in-pandemic) is unknown. We aim to investigate the relationship between the expression of stress-reactive proteins and of ACE2 and TMPRSS2 in endometria collected from women during these two different time frames. METHODS: We retrospectively retrieved tissue blocks of endometrial samples from 25 women in 2019 (pre-pandemic) and 25 women in 2020 (in-pandemic) who underwent hysterectomy for different gynecological indications. Immunohistochemical analysis was performed with endometrial tissue samples that were collected before and during the pandemic, using respective antibodies targeting ACE2/TMPRSS2, ADRB2 and NK1R (stress and anxiety receptor markers, respectively). The quantification of immunoreactive cells for each marker was calculated by the immunoreactive score (IRS) analysis. This retrospective cohort study was limited to small sample size. RESULTS: No significant differences in the IRS of ACE2 and TMPRSS2 were found between the endometria that were collected before and during the pandemic with a lack of correlation between ACE2 and TMPRSS2 expression in respective endometria (r = 0.11, pre-pandemic; r = 0.04, in-pandemic). The immunostaining levels of stress marker, ADRB2 were significantly higher in the endometria of in-pandemic group (p = 0.015) comparing to that of pre-pandemic group. Pearson's correlation coefficient analysis showed a significant correlation in the expression between ADRB2 and TMPRSS2 (r = 0.41, p = 0.042) in the endometria of in-pandemic group but not in the pre-pandemic group. CONCLUSION: The rise in stress and anxiety among women during current pandemic may elicit substantial amount of tissue stress reaction with consequent increase in the expression of SARS-CoV-2 viral entry proteins in their endometria. A lack of correlation between ACE2 and TMPRSS2 expression in endometria may reassure women in their reproductive age that they are not more susceptible to infection by SARS-CoV-2 and suggest that stressful women during this pandemic can safely decide to conceive naturally or by artificial reproductive technology.

A targeted educational programme improves fundamental knowledge of menstrual pain and endometriosis in young women: The Endometriosis Awareness Promotion Project.

RESEARCH QUESTION: Would a properly designed educational programme offered to young women improve their awareness and fundamental knowledge of menstrual pain and endometriosis? DESIGN: A multinational cross-sectional study using a pen-and-paper questionnaire among women aged 19-24 years was conducted between 2017 and 2019 to assess fundamental knowledge of menstrual pain and endometriosis. Improvement in knowledge was also analysed using a separate questionnaire completed before, and 1-3 months after, a group discussion, lecture on menstrual pain and endometriosis, or both. RESULTS: Among three groups of students (college [n = 271], medical [n = 877] and nursing [n = 763]), knowledge of menstrual pain and endometriosis was lowest among college students, modest among nursing students and fair among medical students (P < 0.001 for each). The experience of cyclical pain, even when painkillers were taken, was reported by 15.5%, 4.6% and 3.8% of students, respectively. Most students managed their cyclical pain by enduring it or by taking over-the-counter medication. An informative education programme with group discussions, lectures, or both, was successful in improving knowledge and consequences of menstrual pain and endometriosis. Proper education and dissemination of knowledge to college students failed to motivate them to visit gynaecologists; however, medical and nursing students became highly interested in visiting gynaecologists. CONCLUSIONS: An educational programme can improve awareness and knowledge of endometriosis and dysmenorrhoea among young women. The programme motivated nursing and medical students, but not college students, to seek medical attention for early detection and management of endometriosis.

Occurrence of chronic endometritis in different types of human adenomyosis.

Purpose: Human adenomyosis has an adverse effect on female fertility. Exact mechanistic basis is still unclear. We investigated the occurrence of chronic endometritis (CE) in different types of human adenomyosis. Methods: This is a prospective non-randomized observational study enrolling patients with focal (n = 30), diffuse (n = 26), intrinsic (n = 23), and extrinsic (n = 10) adenomyosis. Endometrial biopsy samples were collected from hysterectomy specimens. Immunohistochemical analysis was performed using antibody against CD68 (Mφ marker) with biopsy samples of intrinsic/extrinsic adenomyosis and CD138 (Syndecan-1), a marker of plasma cells, in all biopsy samples. Results: In GnRHa-untreated groups, a higher trend in the occurrence of CE, as characterized by infiltration of ≥1 plasma cells in endometrial stroma, was found in women with focal (58.8%, p = 0.0849) and diffuse adenomyosis (60.0%, p = 0.0841) comparing to control women (10.0%). In women with focal adenomyosis, ipsilateral side showed a significantly higher occurrence of CE (58.8%) than on the contralateral side (11.7%) (p = 0.043). Tissue infiltration of macrophages in endometria was significantly higher in intrinsic than in extrinsic adenomyosis (p = 0.03) without showing any significant difference in the occurrence of CE between these two variants of adenomyosis. Conclusion: A variable occurrence of CE in different types of adenomyosis may be involved in adverse reproductive outcome.

An axonemal alteration in apical endometria of human adenomyosis.

STUDY QUESTION: Is there any change in the distribution of microvilli and microtubules in the apical endometria of women with adenomyosis? SUMMARY ANSWER: We observed microvilli damage in the apical endometria and an axonemal alteration characterized by abnormal distribution of longitudinal bundles of microtubules within microvilli in women with adenomyosis. WHAT IS KNOWN ALREADY: Human adenomyosis has a negative impact on female fertility. Abnormal utero-tubal sperm transport, tissue inflammation and toxic effect of chemical mediators have been proposed as contributing factors. Inflammation-induced damage of mucosal cilia in the Fallopian tube has been reported. However, information on inflammation-induced damage of microvilli on the apical endometrial cells and its core bundles of microtubules in adenomyosis remains unknown. STUDY DESIGN, SIZE, DURATION: This is a prospective cohort study with subjects undergoing laparoscopic surgery or hysterectomy for clinical indication and evaluations of endometrial biopsy samples in two academic university hospitals. During the period between March 2015 and December 2018, endometrial biopsy samples were prospectively collected from 15 control women and 45 women with adenomyosis for immunohistochemical analysis and a separate cohort of 10 control women with cervical intraepithelial neoplasia Grade 3 (CIN3) and 20 women with adenomyosis for analysis by immunohistochemistry and transmission electron microscopy (TEM). PARTICIPANTS/MATERIALS, SETTING, METHODS: For immunohistochemical study, endometrial biopsy samples were prospectively collected from 15 control women with fibroids, 25 women with focal adenomyosis and 20 women with diffuse adenomyosis after surgery. The diagnosis of fibroid and adenomyosis was made clinically by transvaginal ultrasonography and magnetic resonance imaging and confirmed by histology. Immunohistochemical analysis was performed retrospectively using antibody against CD68 (marker of macrophages) in endometrial biopsy specimens of women with and without adenomyosis. TEM was performed with the apical endometria collected from a separate cohort of 10 control women with CIN3 and 20 women with focal and diffuse adenomyosis for the identification of any change in the distribution of microvilli and longitudinal bundles of microtubules within microvilli. MAIN RESULTS AND ROLE OF CHANCE: Comparing to control endometria and contralateral side, tissue infiltration of macrophages (Mφ) in the endometria was significantly higher on the ipsilateral side of focal adenomyosis (P = 0.02 and P = 0.03, respectively) and anterior/posterior walls of diffuse adenomyosis (P = 0.01 for both). In a subgroup analysis of patients with focal adenomyosis with and without symptoms, the endometria of symptomatic women displayed a tendency of higher Mφ infiltration on the ipsilateral side than in asymptomatic women (P = 0.07). Comparing to contralateral side endometria of symptomatic women, Mφ infiltration was significantly higher in the endometria of symptomatic women collected from the ipsilateral side of focal adenomyosis (P = 0.03). We found a significantly less tissue infiltration of Mφ in the endometria of women with CIN3 than that in endometria of women with focal adenomyosis. TEM analysis showed that number of microvilli in the endometria was significantly decreased on the ipsilateral side (P = 0.003) comparing to that on the contralateral side of focal adenomyosis. The Chi-squared test indicated that cases with abnormal (disruption in the normal arrangement of 9 peripheral pairs + 1 central pair) microtubules (MT) were significantly higher in women with adenomyosis than in cases with normal patterns (P = 0.0016). While contralateral side displayed significantly less abnormal MT (P = 0.0002), ipsilateral side of focal adenomyosis showed significantly higher abnormal MT (P = 0.0164) comparing to normal patterns. Cases with symptomatic adenomyosis showed significantly higher abnormal MT than normal MT (P = 0.0004). An axonemal alteration characterized by abnormal structural distribution of microtubules within microvilli in the apical endometria in response to endometrial inflammation may be involved in adverse reproductive outcome in women with adenomyosis. LIMITATIONS, REASONS FOR CAUTION: The average age of women in this study was high that may be associated with overall decline in fertility regardless of the presence or absence of adenomyosis or endometriosis. We collected endometrial biopsy samples from two completely separate cohorts of women for analysis by immunohiostochemistry and TEM. We need future follow-up study with increased sample size and from the same patients to precisely clarify the mechanistic link between axonemal alteration and negative fertility outcome. WIDER IMPLICATIONS OF THE FINDINGS: Our current findings may have some biological implication to better understand the endometrial epithelial biology and pathology in women with adenomyosis and may open the avenue for future study in other reproductive diseases. The ultra-structural abnormalities of microvilli and microtubules in the apical endometria in response to tissue inflammatory reaction may clarify the possible association between negative fertility outcome and adenomyosis. Our findings may be clinically useful during counseling with symptomatic patients with adenomyosis desiring pregnancy. STUDY FUNDING/COMPETING INTEREST (S): This work was supported by Grants-in-Aid for Scientific Research from the Ministry of Education, Sports, Culture, Science and Technology of Japan. There is no conflict of interest related to this study. TRIAL REGISTRATION NUMBER: N/A.

Peroxisome proliferator-activated receptor-γ coactivator 1α-mediated pathway as a possible therapeutic target in endometriosis.

STUDY QUESTION: Is a peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α)-mediated pathway involved in the development of endometriosis? SUMMARY ANSWER: PGC-1α plays critical roles in inflammation and cell proliferation of endometriotic tissues and may be involved in the development of endometriosis. WHAT IS KNOWN ALREADY: Expression levels of PGC-1α are higher in ovarian endometrioma (OE) than normal endometrium (NE). PGC-1α also stimulates aromatase activity and promotes local estrogen biosynthesis in OE. STUDY DESIGN, SIZE, DURATION: This is a case-controlled biological study using endometrial cells and tissues derived from 23 women with, and 10 women without, OE. PARTICIPANTS/MATERIALS, SETTING, METHODS: Ectopic endometriotic and eutopic endometrial stromal cells (SCs) were isolated and maintained in culture. PGC-1α was either overexpressed in the cells or knocked down using siRNA. The expression of PGC-1α and other factors during endometriosis was examined using real-time PCR and western blotting, cell proliferation was measured using Cell Counting Kit-8 (WST-8) assays and transcriptional activity was assessed using luciferase reporter assays. MAIN RESULTS AND THE ROLE OF CHANCE: PGC-1α overexpression promoted the proliferation of OESCs in a time-dependent manner (P < 0.01 versus control) but not NESCs. PGC-1α stimulated aromatase (P < 0.01 versus control) and interleukin (IL)-6/IL-8 mRNA expression levels (P < 0.05 versus control for each) and led to inhibitor kappa B phosphorylation protein expression and upregulation of the apoptosis inhibitors X-linked inhibitor of apoptosis protein and survivin at mRNA level (P < 0.05 versus control for each). HX531, a selective retinoid-X receptor-α (RXRα) antagonist, suppressed the PGC-1α-induced cell proliferation (P < 0.05 versus control), aromatase/IL-6/IL-8/survivin mRNA expression (P < 0.05 versus control for each) and transcription reporter activity of PGC-1α in a dose-dependent manner (P < 0.01 versus control). Moreover, HX531 downregulated PGC-1α-induced aromatase-promoter PI.3-II transcripts in OESCs, and PGC-1α knockdown reduced aromatase, IL-6/IL-8 and antiapoptotic factors mRNA expression (P < 0.05 versus control for each). Notably, the Histogram score, which was used for quantifying RXRα status, was markedly higher in OE than in NE tissue (P < 0.01). LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Only OE tissues were included in this study, while peritoneal and deep infiltrating endometriotic tissues were not. Therefore, these findings might not be generalized to other types of endometriosis. WIDER IMPLICATIONS OF THE FINDINGS: In OESC, PGC-1α stimulated cell proliferation and was involved in local estrogen biosynthesis, inflammation and apoptosis, and these effects of PGC-1α were inhibited by HX531. The suppression of PGC-1α-induced proliferation by HX531 in OESCs but not NESCs suggests that the PGC-1α-RXRα axis could play critical roles in promoting endometriosis. This is the first report of a relationship between PGC-1α and inhibitor of apoptosis proteins in endometriosis. Based on these findings, the PGC-1α-mediated pathway could represent a potential target in molecular therapy of endometriosis. STUDY FUNDING/COMPETING INTEREST(S): The study is supported in part by Grants-in-Aid for Scientific Research (15 K10681 and 15 K10726) from the Ministry of Education, Culture, Sports, Science, and Technology (Japan). The authors have no conflicts of interest to disclose.

Association between FOXP3+ regulatory T-cells and occurrence of peritoneal lesions in women with ovarian endometrioma and dermoid cysts.

RESEARCH QUESTION: Is there any relationship between numbers of FOXP3+ regulatory T-cells (Treg) and occurrence of peritoneal lesions in women with ovarian endometrioma and dermoid cysts? DESIGN: Retrospective and prospective case-controlled cohort study. Peritoneal lesions were collected from 27 women with ovarian endometrioma and 25 women with dermoid cysts. Peritoneal fluid was collected from 36 women with ovarian endometrioma and 42 women with dermoid cysts. Tissue expression of Forkhead box P3 (FOXP3), one of the transcription factors of Treg cells, and transforming growth factor-beta (TGF-ß) were examined by immunohistochemistry. Interleukin-6 (IL-6) and TGF-ß levels in the peritoneal fluid were measured by enzyme-linked immunosorbent assay. RESULTS: Ovarian endometrioma cases with coexisting peritoneal lesions were significantly more frequent than dermoid cyst cases with coexistent peritoneal lesions (269/350 [76.9%] versus 74/414 [17.9%]; P < 0.001). Numbers of FOXP3+ Treg cells were significantly higher in peritoneal lesions of women coexistent with ovarian endometrioma (F = 21.52, P < 0.001) and dermoid cysts (F = 22.01, P < 0.001) compared with women without peritoneal lesions. Higher FOXP3+ Treg cell numbers in pathological lesions corresponded with significantly higher TGF-ß (P < 0.001) and lower IL-6 (P = 0.020) levels in peritoneal fluid of women with peritoneal lesions compared with women without lesions. CONCLUSIONS: This study confirms current speculation that endometriosis is related to alteration in Treg cells, causing survival and implantation of ectopic endometrial lesions in women with endometrioma and dermoid cysts. The findings may clarify why only 10% of women in the general population develop endometriosis despite cyclic menstruation with retrograde flow occurring in >90% of women.

Biological differences between focal and diffuse adenomyosis and response to hormonal treatment.

RESEARCH QUESTION: Is there any difference in ovarian steroid receptor expression and pattern of fibrosis in focal and diffuse adenomyosis and response to hormonal treatment? DESIGN: Prospective controlled study where biopsy samples were prospectively collected after surgery from 30 women with focal adenomyosis, 21 women with diffuse adenomyosis and 20 women with uterine myoma. Some of these women underwent 3-6 months of treatment with gonadotrophin-releasing hormone agonist (GnRHa) before surgery. Tissue expression of oestrogen receptor (ER) and progesterone receptor (PR) was analysed by immunohistochemistry. Distribution of tissue fibrosis was examined by Masson's trichrome staining with computer-based image analysis of fibrosis in tissues derived from women with and without adenomyosis. RESULTS: There was no difference in ER/PR expression in gland cells/stromal cells of adenomyotic lesions on the ipsilateral side of focal adenomyosis and the anterior/posterior walls of diffuse adenomyosis. Compared to myoma tissues, a relatively decreased expression of ovarian steroid receptors was observed in both focal and diffuse adenomyosis. Image analysis of tissue fibrosis indicated more fibrosis in both focal and diffuse adenomyosis compared to fibrosis in the myometrium derived from women with uterine myoma. The pattern of fibrosis was no different in tissues derived from GnRHa-treated and -untreated women with focal and diffuse adenomyosis. CONCLUSIONS: No difference was found in the expression of ER/PR and entity of fibrosis between women with focal and diffuse adenomyosis regardless of GnRHa treatment. A lower expression of ER/PR compared to myoma tissue potentially clarifies the biological rationale of non-response to hormonal therapies for adenomyosis.

Biological differences between intrinsic and extrinsic adenomyosis with coexisting deep infiltrating endometriosis.

RESEARCH QUESTION: Is there a biological difference between intrinsic and extrinsic adenomyosis with coexisting deep infiltrating endometriosis (DIE)? DESIGN: In this prospective controlled study, biopsy specimens were collected after surgery from 23 women with intrinsic adenomyosis and 10 women with extrinsic adenomyosis with coexisting DIE lesions. Histological evaluation was carried out by immunoreaction to Ber-EP4 (epithelial cell marker) and CD10 (stromal cell marker). Tissue expression of oestrogen and progesterone receptors was analysed by immunohistochemistry. Tissue fibrosis was examined by Masson's trichrome staining with computer-based image analysis of fibrosis in respective samples. RESULTS: The detection rate of coexistent DIE was significantly higher in women with extrinsic adenomyosis (9/10 [90.0%]) than in women with intrinsic adenomyosis (3/23 [13.0%]; P < 0.001). The pattern of Ber-EP4-stained glands and CD10-stained stromal cells of extrinsic adenomyosis was similar to that of coexistent DIE lesions. In contrast, the pattern of gland and stromal cells was similar to the endometrium in the cases with intrinsic adenomyosis. Unlike extrinsic adenomyosis, progesterone receptor expression was significantly decreased in both gland cells (P < 0.05) and stromal cells (P < 0.05) of intrinsic adenomyosis. Although relatively more fibrosis was seen in biopsy samples of extrinsic adenomyosis and coexistent DIE than in intrinsic adenomyosis and their coexistent DIE, no significant difference was found. CONCLUSIONS: Extrinsic adenomyosis may be considered as adenomyosis externa based on a close histological and biological relationship between extrinsic adenomyosis and coexistent DIE. Our findings may contribute to the understanding of a possible biological origin of two newly classified intrinsic and extrinsic adenomyosis.

Local estrogen formation and its regulation in endometriosis.

BACKGROUND: It has been well established that endometriosis is an estrogen-dependent disease. Although the exact pathogenesis of the disease is still unclear, it is known to be characterized by estrogen-dependent growth and maintenance of the ectopic endometrium and increased local estrogen production. METHODS: The authors reviewed studies on local estrogen production and estrogen activities mediated by estrogen receptors in endometriotic tissues. MAIN FINDINGS: Aberrant expression of several enzymes in local endometriotic lesions contributed to the production and metabolism of estrogens. Aromatase was one of the key therapeutic targets for the regulation of local estrogen formation. Our findings suggest that PGC-1a, a transcriptional coactivator-modulating steroid hormone, regulates aromatase expression and activity. Estrogen activities mediated by different types of estrogen receptors abnormally elevated in local tissues could also be involved in the development of endometriosis. The authors demonstrated that the isoflavone aglycone, a partial agonist of the estrogen receptor, suppressed the formation of endometriotic lesions. CONCLUSIONS: Local estrogen production and estrogen activity mediated by estrogen receptors are important potential therapeutic targets for endometriosis.

Aromatase as a target for treating endometriosis.

Endometriosis is a common gynecological disease that causes various clinical symptoms, such as chronic pelvic pain, dysmenorrhea and infertility, seriously affecting women's health and their quality of life. The symptoms and endometriotic lesions are relieved, in many cases, after menopause, when estrogen levels are lowered. Therefore, endometriosis is considered to be estrogen-dependent. Aromatase, the enzyme responsible for the last step of estrogen biosynthesis converting testosterone and androgen to estrogen, was previously reported to be more abundant in endometriotic tissues than in the normal endometrium, leading to an increased local estrogen concentration. Therefore, aromatase is considered a key therapeutic target for regulating local estrogen biosynthesis in endometriosis. A more complete understanding of the mechanisms that modulate aromatase and its activity is required to develop novel estrogen-targeted therapies for endometriosis. In this review article, we outline the current understanding of the pathological processes involved in estrogen production in endometriosis and propose novel strategies to treat this disorder.

Bacterial contamination hypothesis: a new concept in endometriosis.

BACKGROUND: Endometriosis is a multifactorial disease that mainly affects women of reproductive age. The exact pathogenesis of this disease is still debatable. The role of bacterial endotoxin (lipopolysaccharide, LPS) and Toll-like receptor 4 (TLR4) in endometriosis were investigated and the possible source of endotoxin in the pelvic environment was examined. METHODS: The limulus amoebocyte lysate test was used to measure the endotoxin levels in the menstrual fluid and peritoneal fluid and their potential role in the growth of endometriosis was investigated. Menstrual blood and endometrial samples were cultured for the presence of microbes. The effect of gonadotrophin-releasing hormone agonist (GnRHa) treatment on intrauterine microbial colonization (IUMC) and the occurrence of endometritis was investigated. MAIN FINDINGS RESULTS: Lipopolysaccharide regulates the pro-inflammatory response in the pelvis and growth of endometriosis via the LPS/TLR4 cascade. The menstrual blood was highly contaminated with Escherichea coli and the endometrial samples were colonized with other microbes. A cross-talk between inflammation and ovarian steroids or the stress reaction also was observed in the pelvis. Treatment with GnRHa further worsens intrauterine microbial colonization, with the consequent occurrence of endometritis in women with endometriosis. CONCLUSION: For the first time, a new concept called the "bacterial contamination hypothesis" is proposed in endometriosis. This study's findings of IUMC in women with endometriosis could hold new therapeutic potential in addition to the conventional estrogen-suppressing agent.

Association between Uterine Adenomyosis and Infertility: Role of Axonemal Alteration in Apical Endometria.

ABSTRACT: Uterine adenomyosis is an estrogen-dependent chronic inflammatory condition and may cause painful symptoms, abnormal uterine bleeding, and/or subfertility/infertility. It is characterized by the presence of endometrial glands and stroma within the myometrium causing enlargement of the uterus as a result of reactive hyperplastic and/or hypertrophic change of the surrounding myometrium. Similar to endometriosis, adenomyosis has a negative impact on female fertility. Abnormal uterotubal sperm transport, tissue inflammation, and the toxic effect of chemical mediators have been proposed as contributing factors. Inflammation-induced damage of the mucosal cilia in the fallopian tube has been reported. Besides other proposed mechanisms, our most recent study with transmission electron microscopy analysis indicated that microvilli damage and an axonemal alteration in the apical endometria occur in response to endometrial inflammation. This may be involved in the negative fertility outcome in women with adenomyosis. We present a critical analysis of the literature data concerning the mechanistic basis of infertility in women with adenomyosis and its impact on fertility outcome.

The role of innate and adaptive immunity in endometriosis.

The innate and adaptive immune systems are the two key branches that determine host protection at all mucosal surfaces in human body, including the female reproductive tract. The pattern recognition receptors within the host that recognize pathogen-associated molecular patterns are expressed on the cells of the innate immune system. Rapidly reactive, theinnate immune system, responds immediately to the presence of infectious or other non-self agents, thereby launching an inflammatory response to protect the host until the activation of slower adaptive immune system. Macrophages, dendritic cells, and toll-like receptors are integral components of the innate immune system. In contrast, T-helper (Th1/Th2/Th17) cells and regulatory T (Treg) cells are the primary components of adaptive immune system. Studies showed that the growth and progression of endometriosis continue even in unilateral ovariectomized animal suggesting that besides ovarian steroid hormones, the growth of endometriosis could be regulated by innate/adaptive immune systems in pelvic environment. Recent reports demonstrated a potential role of Th1/Th2/Th17/Treg cells either individually or collectively in the initiation, maintenance, and progression of endometriosis. Herewe review the fundamental knowledge of innate and adaptive immunity and elaborate the role of innate and adaptive immunity in endometriosis based on both human and experimental data.

Neonatal uterine bleeding: Risk factors and its association with endometriosis-related symptoms later in life.

OBJECTIVE: We examined the prevalence and risk factors in association with neonatal uterine bleeding (NUB) by retrospective search of contemporary and historical medical records and investigated the possible association between the history of NUB at birth and endometriosis-related symptoms later in life who are now young women. STUDY DESIGN: This was a retrospective case-controlled cohort study and prospective evaluation of web-based questionnaire survey on symptoms related to endometriosis among young women born with and without NUB. Multiple regression analysis was performed incorporating various confounding variables that may influence the occurrence of NUB or the reporting of endometriosis symptoms later in life. RESULTS: Among the 1093 female neonates born between 1996 and 2000, 105 of them had NUB, yielding with a prevalence of 9.6 %. Of the 807 female babies born between 2013 and 2017, 25 (3.1 %) had NUB. Multiple Logistic regression analysis indicated that younger age of the mother [odds ratio (OR) = 0.92, 95 % confidence interval (CI) = 0.85-1.00, P = 0.048] and longer gestational age of 39 weeks (OR = 3.04, 95 % CI = 1.43-6.45, P = 0.004) and of ≥ 40 weeks (OR = 4.54, 95 % CI = 2.20-9.39, P < 0.0001) of gestation were significantly associated with the occurrence of NUB. While the possibility of recall bias cannot be ruled out, newborn females who had a history of NUB appeared to complain of various endometriosis-related symptoms later in life during adulthood. CONCLUSIONS: We confirmed the validity of the reported prevalence and risk factors of NUB. NUB indeed occurs with a prevalence of 3-10% during the historical and contemporary period. Longer gestational age and younger maternal age may be considered as high-risk factors for the occurrence of NUB. The clinical relevance of our findings remains to be elucidated. Future prospective studies, preferably with larger sample sizes and the inclusion of NUB cases after discharge from the hospital, may further illuminate some unresolved issues. We also need to confirm the endometriosis-related symptoms in women with and without history of NUB via more definitive diagnosis such as imaging and histology.

Low-Nutrient Environment-Induced Changes in Inflammation, Cell Proliferation, and PGC-1α Expression in Stromal Cells with Ovarian Endometriosis.

Although nutrient status plays an important role in cell metabolism, its significance in endometriosis is obscure. Herein, we investigated the effects of a low-nutrient microenvironment on endometriosis. Stromal cells (SCs) from ovarian endometrioma (OESCs) or normal endometrium without endometriosis (NESCs) were isolated and cultured. A low-nutrient microenvironment was replicated by replacing the culture medium with Hank's balanced salt solution. OESC and NESC proliferation under the low-nutrient condition was measured. The expression of exacerbating factors in endometriosis under the low-nutrient condition was examined at the mRNA and protein levels. OESCs showed higher proliferation than NESCs under the low-nutrient condition. In OESCs, the low-nutrient condition upregulated the mRNA expression of vascular endothelial growth factor (VEGF), interleukin-6 and -8, aromatase, Bcl-2, and peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) and downregulated that of BAX and induced transcription of PI.3, PII, and exon II. Western blotting revealed elevated VEGF and PGC-1α expression under the low-nutrient condition in OESCs. These changes coincided with the elevated expression of PGC-1α, which was reduced at the mRNA level upon nutrient status rescue. Endometriosis is exacerbated by altered angiogenesis, inflammation, anti-apoptosis, and local estrogen production while trying to survive under a low-nutrient microenvironment; it may be attributed to PGC-1α-mediated metabolic mechanisms.

Hepcidin as a key regulator of iron homeostasis triggers inflammatory features in the normal endometrium.

Menstrual blood, containing high iron levels, can undergo retrograde transport into the abdominal cavity. Excess iron causes oxidative stress and inflammation. Iron metabolism is regulated by hepcidin, and serum hepcidin levels are increased in patients with endometriosis; however, the functions of hepcidin in normal endometrium remain unclear. We therefore aimed to examine hepcidin concentrations in patients with endometriosis and to determine if iron accumulation and hepcidin increased the production of reactive oxygen species (ROS) and inflammation in normal endometrial cells. We determined hepcidin levels in peritoneal fluid and menstrual blood from patients with and without endometriosis (25/16 and 15/15 patients, respectively). We also examined the effects of hepcidin on ferroportin expression, iron accumulation, and ROS generation in normal endometrial stromal cells (NESCs) from 20 women who underwent surgery for uterine leiomyoma, using immunohistochemistry and immunofluorescence analyses and analyzed its effect on the expression of inflammatory cytokines by real-time polymerase chain reaction. There was no significant difference in iron concentrations in menstrual blood or peritoneal fluid between women with and without endometriosis; however, women with endometriosis had significantly higher hepcidin levels in menstrual blood. Hepcidin reduced the expression of ferroportin in NESCs and promoted the accumulation of ferrous iron. Hepcidin plus ferrous iron increased the production of ROS and inflammatory cytokines compared with ferrous iron alone. These results indicate that women with endometriosis have high hepcidin levels in menstrual blood, leading to increased iron production, oxidative stress, and inflammation, which may, in turn, promote the development of endometriosis.

Pathogenesis of Human Adenomyosis: Current Understanding and Its Association with Infertility.

The aim of this review article was to summarize our current understanding on the etiologies and pathogenesis of human adenomyosis and to clarify the relative association between adenomyosis and infertility. The exact pathogenesis of adenomyosis is still elusive. Among different reported concepts, direction invagination of gland cells from the basalis endometrium deep into myometrium is the most widely accepted opinion on the development of adenomyosis. According to this concept, endometrial epithelial cells and changed fibroblasts, abnormally found in the myometrium in response to repeated tissue injury and/or disruption at the endometrium-myometrium interface (EMI), elicit hyperplasia and hypertrophy of the surrounding smooth muscle cells. In this review, a comprehensive review was performed with a literature search using PubMed for all publications in English and Japanese (abstract in English), related to adenomyosis and infertility, from inception to April 2021. As an estrogen-regulated factor, hepatocyte growth factor (HGF) exhibits multiple functions in endometriosis, a disease commonly believed to arise from the functionalis endometrium. As a mechanistic basis of gland invagination, we investigated the role of HGF, either alone or in combination with estrogen, in the occurrence of epithelial-mesenchymal transition (EMT) in adenomyosis. Aside from microtrauma at the EMI, metaplasia of displaced Müllerian remnants, differentiation of endometrial stem/progenitor cells within the myometrium and somatic mutation of some target genes have been put forward to explain how adenomyosis develops. In addition, the possible role of microRNAs in adenomyosis is also discussed. Besides our knowledge on the conventional classification (focal and diffuse), two recently proposed classifications (intrinsic and extrinsic) of adenomyosis and the biological differences between them have been described. Although the mechanistic basis is unclear, the influence of adenomyosis on fertility outcome is important, especially considering the recent tendency to delay pregnancy among women. Besides other proposed mechanisms, a recent transmission election microscopic (TEM) study indicated that microvilli damage and an axonemal alteration in the apical endometria of human adenomyosis, in response to endometrial inflammation, may be involved in negative fertility outcomes. We present a critical analysis of the literature data concerning the mechanistic basis of infertility in women with adenomyosis and its impact on fertility outcome.