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Adenomyosis involves the infiltration of endometrial glands and stroma deep into the uterine tissue, causing disruption to the endometrial–myometrial interface (EMI). The role of interleukin-17 (IL-17) has been extensively studied in endometriosis, but its involvement in adenomyosis remains unclear. This study aimed to investigate the expression of IL-17 in eutopic and ectopic endometrium (adenomyosis) of individuals with adenomyosis at the level of EMI. Paired tissues of eutopic endometrium and adenomyoma were collected from 16 premenopausal women undergoing hysterectomy due to adenomyosis. The IL-17 system was demonstrated in paired tissue samples at the level of EMI by the immunochemistry study. Gene expression levels of IL-17A and IL-17 receptor (IL-17R) were assessed through quantitative real-time reverse transcription polymerase chain reaction (RT-PCR). Comparative gene transcript amounts were calculated using the delta-delta Ct method. By immunohistochemical staining, CD4, IL-17A, and IL-17R proteins were detected in both eutopic endometrium and adenomyosis at the level of EMI. IL-17A and IL-17R were expressed mainly in the glandular cells, and the expression of both IL-17A and IL-17R was found to be stronger in adenomyosis than in endometrium. 3-Diaminobenzidine (DAB) staining revealed greater IL-17A expression in adenomyosis compared to eutopic endometrium. Quantitative RT-PCR showed 7.28-fold change of IL-17A and 1.99-fold change of IL-17R, and the fold change level of both IL-17A and IL-17R is significantly higher in adenomyosis (IL-17A: p = 0.047, IL-17R: p = 0.027) versus eutopic endometrium. We found significantly higher IL-17 levels in adenomyosis compared to eutopic endometrium at the level of EMI. The results showed that the IL-17 system may play a role in adenomyosis. [ABSTRACT FROM AUTHOR]

Adenomyosis is a common disorder of the uterus, and is associated with an enlarged uterus, heavy menstrual bleeding (HMB), pelvic pain, and infertility. It is characterized by endometrial epithelial cells and stromal fibroblasts abnormally found in the myometrium where they elicit hyperplasia and hypertrophy of surrounding smooth muscle cells. While both the mechanistic processes and the pathogenesis of adenomyosis are uncertain, several theories have been put forward addressing how this disease develops. These include intrinsic or induced (1) microtrauma of the endometrial-myometrial interface; (2) enhanced invasion of endometrium into myometrium; (3) metaplasia of stem cells in myometrium; (4) infiltration of endometrial cells in retrograde menstrual effluent into the uterine wall from the serosal side; (5) induction of adenomyotic lesions by aberrant local steroid and pituitary hormones; and (6) abnormal uterine development in response to genetic and epigenetic modifications. Dysmenorrhea, HMB, and infertility are likely results of inflammation, neurogenesis, angiogenesis, and contractile abnormalities in the endometrial and myometrial components. Elucidating mechanisms underlying the pathogenesis of adenomyosis raise possibilities to develop targeted therapies to ameliorate symptoms beyond the current agents that are largely ineffective. Herein, we address these possible etiologies and data that support underlying mechanisms.

Abstract Background Uterine adenomyosis is associated with chronic pelvic pain, abnormal uterine bleeding, and infertility. The pathogenesis of adenomyosis is still unclear. Circular RNAs (circRNAs) have been implicated in several benign diseases and malignant tumors. We aimed to explore the co-dysregulated circular RNA profile in the eutopic endometrium and endometrial–myometrial interface (EMI) of adenomyosis. Methods Total RNA was extracted from the eutopic endometrium and EMI of 5 patients with adenomyosis and 3 patients without adenomyosis. Next-generation sequencing was performed to identify the circRNA expression profile of the two tissue types. Bioinformatics analysis was performed to predict circRNA-binding miRNAs and miRNA-binding mRNAs and construct ceRNA networks, and functional enrichment analysis was performed to predict the biological functions of circRNAs. Results Among the adenomyosis patients, 760 circRNAs were significantly upregulated and 119 circRNAs were significantly downregulated in the EMI of adenomyosis, while 47 circRNAs were significantly upregulated and 17 circRNAs were significantly downregulated in the eutopic endometrium of adenomyosis. We identified hsa_circ_0002144 and hsa_circ_0005806 as co-upregulated and hsa_circ_0079536 and hsa_circ_0024766 as co-downregulated in the eutopic endometrium and EMI. Bioinformatics analysis was performed to construct a ceRNA network of codifferentially expressed circRNAs. The MAPK signaling pathway is the most important signaling pathway involved in the function of the ceRNA network. Conclusions Co-dysregulated circRNAs were present in the eutopic endometrium and EMI of adenomyosis. MiRNA binding sites were observed for all of these circRNAs and found to regulate gene expression. Co-dysregulated circRNAs may induce the eutopic endometrial invagination process through the MAPK signaling pathway and promote the progression of adenomyosis.

Background: Uterine adenomyosis is associated with chronic pelvic pain, abnormal uterine bleeding, and infertility. The pathogenesis of adenomyosis is still unclear. Circular RNAs (circRNAs) have been implicated in several benign diseases and malignant tumors. We aimed to explore the co-dysregulated circular RNA profile in the eutopic endometrium and endometrial-myometrial interface (EMI) of adenomyosis.Methods: Total RNA was extracted from the eutopic endometrium and EMI of 5 patients with adenomyosis and 3 patients without adenomyosis. Next-generation sequencing was performed to identify the circRNA expression profile of the two tissue types. Bioinformatics analysis was performed to predict circRNA-binding miRNAs and miRNA-binding mRNAs and construct ceRNA networks, and functional enrichment analysis was performed to predict the biological functions of circRNAs.Results: Among the adenomyosis patients, 760 circRNAs were significantly upregulated and 119 circRNAs were significantly downregulated in the EMI of adenomyosis, while 47 circRNAs were significantly upregulated and 17 circRNAs were significantly downregulated in the eutopic endometrium of adenomyosis. We identified hsa_circ_0002144 and hsa_circ_0005806 as co-upregulated and hsa_circ_0079536 and hsa_circ_0024766 as co-downregulated in the eutopic endometrium and EMI. Bioinformatics analysis was performed to construct a ceRNA network of codifferentially expressed circRNAs. The MAPK signaling pathway is the most important signaling pathway involved in the function of the ceRNA network.Conclusions: Co-dysregulated circRNAs were present in the eutopic endometrium and EMI of adenomyosis. MiRNA binding sites were observed for all of these circRNAs and found to regulate gene expression. Co-dysregulated circRNAs may induce the eutopic endometrial invagination process through the MAPK signaling pathway and promote the progression of adenomyosis. [ABSTRACT FROM AUTHOR]

• Mechanically and thermally induced EMID causes adenomyosis • Mechanical EMID confers a higher risk of developing adenomyosis than thermal EMID • The risk of developing adenomyosis seems to be related to the extent of damage • Perioperative NK1R inhibitor and β-blocker may reduce the risk of adenomyosis Do uterine procedures potentially disrupting the endometrial–myometrial interface (EMI) induce adenomyosis? Six prospective, randomized controlled experiments were conducted involving a total of 106 female BALB/c and 12 female C57BL/6 mice. The incidence of adenomyosis was evaluated in these two strains of mouse after mechanically induced EMI disruption (EMID), or thermally induced EMID using electrocoagulation of different intensities. Finally, the incidence was evaluated in mice that had received perioperative administration of aprepitant (an NK1R inhibitor), propranolol (a beta-blocker) or vehicle. Body weight, hot plate latency and grade of myometrial infiltration were evaluated. Histology, immunohistochemistry and histochemistry analyses were also performed. Mechanical injury to the EMI caused EMID. Adenomyosis developed in the majority of mice in the EMID groups 3 months after mechanically induced EMID but did not develop in the control group (83.3% in C57BL/6 mice, P = 0.015; 100% in BALB/c mice, P = 0.0002). With thermally induced EMID, adenomyosis was found in 30% of the EMID mice 10 weeks later, but the incidence increased to 66.7% if the extent of EMID damage was increased. In mice with perioperative administration of aprepitant or propranolol, the incidence of adenomyosis was reduced from 100% to 58.3% (both P = 0.00034). This study provides the first piece of experimental evidence that EMID resulting from iatrogenic uterine procedures can substantially increase the risk of developing adenomyosis, with the risk in proportion to the severity of disruption. More intriguingly, perioperative administration of an NK1R antagonist or beta-blocker significantly reduced the risk of developing adenomyosis. [ABSTRACT FROM AUTHOR]

Adenomyosis is a disease in which ectopic endometrial glands and stromal cells appear in the uterine myometrium. This pathology is common among women of reproductive age, and in addition to chronic pelvic pain and heavy periods it may also cause infertility. The 'tissue injury and repair' mechanism in response to increased intrauterine pressures was proposed as the etiology for migration of fragments of basal endometrium into the myometrial wall. In order to investigate this mechanism, a conceptual two-dimensional model of the uterine wall subjected to intrauterine pressures was implemented using ADINA commercial software. The stress field within the uterine wall was examined for a variety of intrauterine sinusoidal pressure waves with varying frequencies. The results revealed that: (1) as the wavelength of the subjected pressure wave decreased, high concentration of stresses developed near the inner uterine cavity; (2) as the pressure wave frequency increased, high gradients of the stresses were obtained; (3) at menstrual phase, the highest stresses obtained at the endometrial-myometrial interface. Therefore, increased uterine activity results in high stresses which may lead to tissue lesions and detachment of endometrial cells. [ABSTRACT FROM AUTHOR]

The endometrial-myometrial interface (EMI) is a specific functional region of uterus. However, our knowledge on EMI ultrastructure both in normal uterus and adenomyosis is far from enough to understand its pathology. In this study, used the samples of EMI and outer myometrium (OM) from the adenomyosis hysterectomy specimens and the subjects from the control uteri, we prospectively compared the ultrastructure of myocytes from EMI and OM, the ultrastructural changes of EMI between the proliferative and secretory phases, and the ultrastructural difference of EMI between adenomyosis and the control group. In both adenomyosis and control group, there were differences in ultrastructure between myocytes from EMI and OM. Specifically, the myocytes from EMI were rich in organelles. In contrast, the myocytes from OM had abundant contractile structural components. In the proliferative phase, the myocytes from EMI in adenomyosis had significantly smaller cell and nucleus diameter than those from the control group, but in the secretory phase, the difference was not significant. In the control group, the various ultrastructural features of myocytes from EMI including the mean diameter of cell and nuclei and the myofilaments/cytoplasm ratio exhibited cyclical changes, but in adenomyosis, the normal cyclical changes were absent. In conclusions, there are significant ultrastructural differences between the myocytes from EMI and OM. The myocytes in women with adenomyosis were significantly different to the control subjects, primarily because the normal cyclical changes were absent.