Retinoblastoma protein promotes uterine epithelial cell cycle arrest and necroptosis for embryo invasion.

Retinoblastoma protein (RB) encoded by Rb1 is a prominent inducer of cell cycle arrest (CCA). The hormone progesterone (P4 ) promotes CCA in the uterine epithelium and previous studies indicated that P4 activates RB by reducing the phosphorylated, inactive form of RB. Here, we show that embryo implantation is impaired in uterine-specific Rb1 knockout mice. We observe persistent cell proliferation of the Rb1-deficient uterine epithelium until embryo attachment, loss of epithelial necroptosis, and trophoblast phagocytosis, which correlates with subsequent embryo invasion failure, indicating that Rb1-induced CCA and necroptosis of uterine epithelium are involved in embryo invasion. Pre-implantation P4 supplementation is sufficient to restore these defects and embryo invasion. In Rb1-deficient uterine epithelial cells, TNFα-primed necroptosis is impaired, which is rescued by the treatment with a CCA inducer thymidine or P4 through the upregulation of TNF receptor type 2. TNFα is expressed in the luminal epithelium and the embryo at the embryo attachment site. These results provide evidence that uterine Rb1-induced CCA is involved in TNFα-primed epithelial necroptosis at the implantation site for successful embryo invasion.

Pregnancy is associated with reduced progression of symptomatic adenomyosis: a retrospective pilot study.

BACKGROUND: Adenomyosis is a common gynecological disease in women of reproductive age and causes various symptoms such as dysmenorrhea and heavy menstrual bleeding. However, the influence of pregnancy on the progression of adenomyosis remains unclear. The insight into whether the size of adenomyosis is increased, decreased, or unchanged during pregnancy is also undetermined. The current study aimed to evaluate the influence of pregnancy in patients with symptomatic adenomyosis. METHODS: This study retrospectively enrolled patients diagnosed with adenomyosis by magnetic resonance imaging between 2015 and 2022 at The University of Tokyo Hospital. Uterine size changes were evaluated by two imaging examinations. In the pregnancy group, the patients did not receive any hormonal and surgical treatments, except cesarean section, but experienced pregnancy and delivery between the first and second imaging examinations. In the control group (nonpregnancy group), the patients experienced neither hormonal and surgical treatments nor pregnancy from at least 1 year before the first imaging to the second imaging. The enlargement rate of the uterine size per year (percentage) was calculated by the uterine volume changes (cm3) divided by the interval (years) between two imaging examinations. The enlargement rate of the uterine size per year was compared between the pregnancy group and the control group. RESULTS: Thirteen and 11 patients with symptomatic adenomyosis were included in the pregnancy group and in the control group, respectively. The pregnancy group had a lower enlargement rate per year than the control group (mean ± SE: -7.4% ± 3.6% vs. 48.0% ± 18.5%, P < 0.001), indicating that the size of the uterus with adenomyosis did not change in the pregnancy group. CONCLUSIONS: Pregnancy is associated with reduced progression of symptomatic adenomyosis.

Current perspectives on endometrial receptivity: A comprehensive overview of etiology and treatment.

Recurrent implantation failure (RIF) remains a challenging problem in assisted reproductive technology (ART). Further insights into uterine abnormalities that can disturb embryo implantation should be obtained. This review provides an overview of the effects of organic and non-organic uterine disorders on endometrial receptivity. The results suggest that various uterine pathologies can lead to defective embryo implantation via multiple mechanisms. In particular, uterine adenomyosis dysregulates molecular and cellular interactions that are vital for successful embryo implantation with a background of chronic inflammation, which may be alleviated by pretreatment with a gonadotropin-releasing hormone agonist. Uterine myomas can cause endometrial deformation and adverse alterations in uterine contractility. Nonetheless, the effectiveness of myomectomy remains debated, and endometrial polyp removal may be considered, particularly in patients with RIF. Chronic endometritis abrogates the appropriate uterine immunological environment critical for embryo implantation. Abnormal endometrial microbiota have been suggested to influence endometrial receptivity; however, supporting evidence is currently scarce. Platelet-rich plasma therapy may be a potential treatment for thin endometria; nevertheless, further validation is required. Endometrial receptivity analysis can detect dysregulation of the window of implantation, and new non-invasive methods for predicting endometrial receptivity have recently been proposed. However, numerous issues still need to be fully clarified. Further clinical and basic studies are necessary to investigate the pathophysiology of defective endometrial receptivity and identify optimal treatments for patients undergoing ART, especially those with RIF.

A gene network of uterine luminal epithelium organizes mouse blastocyst implantation.

Purpose: The receptive endometrium is critical for blastocyst implantation. In mice, after blastocysts enter the uterine cavities on day 4 of pregnancy (day 1 = vaginal plug), blastocyst attachment is completed within 24 h, accompanied by dynamic interactions between the uterine luminal epithelium and the blastocysts. Any failures in this process compromise subsequent pregnancy outcomes. Here, we performed comprehensive analyses of gene expression at the luminal epithelium in the peri-implantation period. Methods: RNA-seq combined with laser microdissection (LMD) was used to reveal unique gene expression kinetics in the epithelium. Results: We found that the prereceptive epithelium on day 3 specifically expresses cell cycle-related genes. In addition, days 3 and 4 epithelia express glutathione pathway-related genes, which are protective against oxidative stresses. In contrast, day 5 epithelium expresses genes involved in glycolysis and the regulation of cell proliferation. The genes highly expressed on days 3 and 4 compared to day 5 are related to progesterone receptor signaling, and the genes highly expressed on day 5 compared to days 3 and 4 are associated with the ones regulated by H3K27me3. Conclusions: These results suggest that specific gene expression patterns govern uterine functions during early pregnancy, contributing to implantation success.

Mdm2-p53-SF1 pathway in ovarian granulosa cells directs ovulation and fertilization by conditioning oocyte quality.

Functions of tumor suppressor p53 and its negative regulator mouse double minute 2 homolog (Mdm2) in ovarian granulosa cells remain to be elucidated, and the current study aims at clarifying this issue. Mice with Mdm2 deficiency in ovarian granulosa cells [ Mdm2-loxP/ progesterone receptor ( Pgr)-Cre mice] were infertile as a result of impairment of oocyte maturation, ovulation, and fertilization, and those with Mdm2/p53 double deletion in granulosa cells ( Mdm2-loxP/ p53-loxP/ Pgr-Cre mice) showed normal fertility, suggesting that p53 induction in the ovarian granulosa cells is detrimental to ovarian function by disturbing oocyte quality. Another model of Mdm2 deletion in ovarian granulosa cells ( Mdm2-loxP/ anti-Mullerian hormone type 2 receptor-Cre mice) also showed subfertility as a result of the failure of ovulation and fertilization, indicating critical roles of ovarian Mdm2 in ovulation and fertilization. Mdm2-p53 pathway in cumulus granulosa cells transcriptionally controlled an orphan nuclear receptor steroidogenic factor 1 (SF1), a key regulator of ovarian function. Importantly, MDM2 and SF1 levels in human cumulus granulosa cells were positively associated with the outcome of oocyte maturation and fertilization in patients undergoing infertility treatment. These findings suggest that the Mdm2-p53-SF1 axis in ovarian cumulus granulosa cells directs ovarian function by affecting their neighboring oocyte quality.-Haraguchi, H., Hirota, Y., Saito-Fujita, T., Tanaka, T., Shimizu-Hirota, R., Harada, M., Akaeda, S., Hiraoka, T., Matsuo, M., Matsumoto, L., Hirata, T., Koga, K., Wada-Hiraike, O., Fujii, T., Osuga, Y. Mdm2-p53-SF1 pathway in ovarian granulosa cells directs ovulation and fertilization by conditioning oocyte quality.

Uterine receptivity, embryo attachment, and embryo invasion: Multistep processes in embryo implantation.

BACKGROUND: Recurrent implantation failure is a critical issue in IVF-ET treatment. Successful embryo implantation needs appropriate molecular and cellular communications between embryo and uterus. Rodent models have been used intensively to understand these mechanisms. METHODS: The molecular and cellular mechanisms of embryo implantation were described by referring to the previous literature investigated by us and others. The studies using mouse models of embryo implantation were mainly cited. RESULTS: Progesterone (P4) produced by ovarian corpus luteum provides the uterus with receptivity to the embryo, and uterine epithelial growth arrest and stromal proliferation, what we call uterine proliferation-differentiation switching (PDS), take place in the peri-implantation period before embryo attachment. Uterine PDS is a hallmark of uterine receptivity, and several genes such as HAND2 and BMI1, control uterine PDS by modulating P4-PR signaling. As the next implantation process, embryo attachment onto the luminal epithelium occurs. This process is regulated by FOXA2-LIF pathway and planar cell polarity signaling. Then, the luminal epithelium at the embryo attachment site detaches from the stroma, which enables trophoblast invasion. This process of embryo invasion is regulated by HIF2α in the stroma. CONCLUSION: These findings indicate that embryo implantation contains multistep processes regulated by specific molecular pathways.

The impact of elevated thyroid stimulating hormone on female subfertility.

Purpose: Hypothyroidism is known to have a negative impact on female reproduction even in subclinical form, subclinical hypothyroidism (SH). This study aimed to investigate the association between elevated TSH level and reproductive outcome. Methods: We retrospectively evaluated a total of 203 infertile women who first visited our infertility treatment division from January 1, 2009 to August 31, 2012, including 13 patients with TSH above 4.5 mIU/l (elevated-TSH patients), 11 of whom were diagnosed as SH, and 190 patients with normal TSH (normo-TSH patients). We evaluated them according to reproductive outcome, including clinical pregnancy, miscarriage, and live birth until April 31, 2014. We also aimed to redefine the upper limit of normal serum TSH level. Results: Multivariate analysis showed significant influence of elevated TSH on clinical pregnancy, although miscarriage and live birth were not affected. In addition, we revealed that the rate of decreased ovarian reserve and unexplained infertility was increased in patients with elevated TSH levels. Conclusions: We found an association between elevated TSH and the decreased rate of clinical pregnancy. This might be related to an ovulatory disorder and pathophysiology of unexplained infertility. These results may reinforce the usefulness of TSH screening in infertility population.

Photocatalytic dehydrative etherification of alcohols with a nanoporous gold catalyst.

A simple and efficient photocatalytic approach for dehydrative etherification of alcohols has been developed by a nanoporous gold catalyst. This protocol features no requirement of addition of acids or bases, broad substrate generality, and excellent acid-sensitive functional group tolerance. The mechanistic studies demonstrate the heterogeneous nature of the catalytic system and the recyclability of the catalyst was demonstrated repeatedly.

DNA Methylation and Histone Modification Are the Possible Regulators of Preimplantation Blastocyst Activation in Mice.

Under ovarian hormone control, dormant blastocysts obtain implantation capacity (known as blastocyst activation) through their global gene expression. After the activated blastocysts communicate with the receptive uterus, the implantation-competent blastocysts start the implantation. Although dormant and activated blastocysts have different gene expression levels, the regulatory mechanisms underlying these transcriptions remain unclear. Hence, this study aimed to analyze epigenetic marks in dormant and activated blastocysts. In mice, blastocyst dormancy is artificially induced by daily progesterone injection without estrogen supplementation after peri-implantation ovariectomy; when estrogen is administered concomitantly, blastocyst activation and implantation occur. These phenomena demonstrate a mouse model of delayed implantation. We collected dormant and activated blastocysts from a delayed implantation mouse model. RNA-seq, methylated DNA immunoprecipitation (MeDIP)-seq, and chromatin immunoprecipitation (ChIP)-seq for H3K4 me3 and H3K27 me3 were performed using dormant and activated blastocysts. Cell cycle-related transcripts were affected during blastocyst activation. DNA methylations were accumulated in downregulated genes in the activated blastocysts. Histone H3 trimethylations were globally altered between the dormant and activated blastocysts. Dormant and activated blastocysts have unique methylation patterns on DNA and histone H3, with high correlation to gene expression. DNA methylation and histone modification can regulate preimplantation blastocyst activation.

Levonorgestrel-Releasing Intrauterine System Improves Menorrhagia-Related Quality of Life in Patients with Symptomatic Adenomyosis.

Levonorgestrel-releasing intrauterine system (LNG-IUS) relieves dysmenorrhea and heavy menstrual bleeding (HMB) in adenomyosis. However, its efficacy on health-related quality of life (HR-QOL) in patients with symptomatic adenomyosis remains unclear. The menorrhagia multi-attribute scale (MMAS), which measures HR-QOL improvement through the treatment of HMB, has never been used for evaluating menorrhagia-specific HR-QOL in patients with symptomatic adenomyosis. Hence, this study aimed to investigate the efficacy of LNG-IUS in improving menorrhagia-specific HR-QOL in these patients using the MMAS. The participants were diagnosed by magnetic resonance imaging. We also assessed the relationships between menorrhagia-specific HR-QOL, blood hemoglobin levels, and the degree of dysmenorrhea before and during LNG-IUS treatment. The LNG-IUS treatment improved the menorrhagia-specific HR-QOL more effectively in incipient type adenomyosis than in advanced type adenomyosis. The efficacy of LNG-IUS treatment on dysmenorrhea evaluated by the visual analog scale score tended to be better in the incipient type than in the advanced type. By the treatment of LNG-IUS, the blood hemoglobin level was not improved in the advanced type but in the incipient type. Furthermore, dysmenorrhea and HMB-related anemia were associated with HR-QOL impairment, and LNG-IUS treatment may improve the HR-QOL by relieving the symptoms. In conclusion, the effectiveness of LNG-IUS on HR-QOL is decreased by advanced adenomyosis. Thus, magnetic resonance imaging use should be reinforced to predict LNG-IUS efficacy in improving the HR-QOL of patients with adenomyosis.

The EZH2-PRC2-H3K27me3 axis governs the endometrial cell cycle and differentiation for blastocyst invasion.

Infertility occurs in 15% of couples worldwide. Recurrent implantation failure (RIF) is one of the major problems in in vitro fertilization and embryo transfer (IVF-ET) programs, and how to manage patients with RIF to achieve successful pregnancy outcomes remains unresolved. Here, a uterine polycomb repressive complex 2 (PRC2)-regulated gene network was found to control embryo implantation. Our RNA-seq analyses of the human peri-implantation endometrium obtained from patients with RIF and fertile controls revealed that PRC2 components, including its core enzyme enhancer of zeste homolog 2 (EZH2)-catalyzing H3K27 trimethylation (H3K27me3) and their target genes are dysregulated in the RIF group. Although fertility of uterine epithelium-specific knockout mice of Ezh2 (eKO mice) was normal, Ezh2-deleted mice in the uterine epithelium and stroma (uKO mice) exhibited severe subfertility, suggesting that stromal Ezh2 plays a key role in female fertility. The RNA-seq and ChIP-seq analyses revealed that H3K27me3-related dynamic gene silencing is canceled, and the gene expression of cell-cycle regulators is dysregulated in Ezh2-deleted uteri, causing severe epithelial and stromal differentiation defects and failed embryo invasion. Thus, our findings indicate that the EZH2-PRC2-H3K27me3 axis is critical to preparing the endometrium for the blastocyst invasion into the stroma in mice and humans.

Uterine Receptivity is Reflected by LIF Expression in the Cervix.

Recurrent implantation failure is a major problem in assisted reproductive technology (ART). Although ART systems have evolved rapidly over the decades, it is still difficult to diagnose uterine conditions suitable for embryo transfer (ET) without the use of invasive endometrial procedures. Previous studies in mice showed that leukemia inhibitory factor (LIF) is a well-known endometrial biomarker for uterine implantation capacity, also known as uterine receptivity. This study focused on LIF in the mouse and human cervix as a possible biomarker of implantation capacity. We found that high expression of LIF in the cervical epithelium is strongly correlated with that of the uterine epithelium during the peri-implantation period in mice. Likewise, human cervical epithelia also exhibit elevated levels of LIF in the peri-implantation period. In addition, cervical LIF is downregulated in mice with defective implantation caused by pharmacological treatments. These results indicated that cervical LIF is a possible biomarker that detected uterine receptivity without invasive endometrial damage.

Oral Gonadotropin-Releasing Hormone Antagonist Relugolix Has the Same Effect as Gonadotropin-Releasing Hormone Agonist Injections in Terms of Preparation for Transcervical Resection Myomectomy.

For preparing the optimal condition in transcervical resection (TCR) surgery, gonadotropin-releasing hormone (GnRH) agonist has been utilized. Recently, an oral GnRH antagonist (relugolix) is available and acts directly on GnRH receptor, avoiding flare up and reducing blood E2 levels rapidly. We retrospectively compared the oral GnRH antagonist (n = 14) effect to that of subcutaneous GnRH agonist (n = 19) for the pretreatment of endometrium in TCR myomectomy. Endometrial thickening was determined by intraoperative videos. The color tone of the endometrium in the normal part was assessed by digital image processing. The median duration of the first GnRH agonist injection and the surgery was 67 days (21-136 days), which is significantly longer than that of the oral GnRH antagonist group, 18.5 days (7-157 days P < 0.01). Both the GnRH agonist and antagonist groups did not exhibit prominence in the endometrium. The GnRH antagonist group showed the same degree of whiteness in the normal endometrium as the GnRH agonist group. The oral GnRH antagonist administration could rapidly atrophy the endometrium and create an optimal surgical field for TCR in a short period.

Constant Activation of STAT3 Contributes to the Development of Adenomyosis in Females.

Adenomyosis is a benign uterine disease that causes dysmenorrhea, heavy menstrual bleeding, and infertility; however, its pathophysiology remains unclear. Since signal transducer and activator of transcription 3 (STAT3) is crucial for endometrial regeneration, we hypothesized that STAT3 participates in adenomyosis pathophysiology. To investigate the influence of STAT3 on adenomyosis development, this study was performed using a novel mouse model of adenomyosis and human specimens of eutopic endometria and adenomyosis lesions. We established a novel mouse model of adenomyosis by puncturing entire mouse uterine layers with a thin needle. Mouse eutopic and ectopic endometria showed a positive immunoreactivity for phosphorylated STAT3 (pSTAT3), the active form of STAT3. Decreased numbers of adenomyotic lesions and reduced expression of Cxcl1, Icam1, and Spp1, which are associated with immune cell chemotaxis and tissue regeneration, were observed in uterine Stat3-deficient mice compared with the controls. In humans, pSTAT3 was intensely expressed at both the eutopic endometrium and the adenomyotic lesions regardless of the menstrual cycle phases. Conversely, it was limitedly expressed in the eutopic endometrium during the menstrual and proliferative phases in women without adenomyosis. Our findings indicate that continuous STAT3 activation promotes adenomyosis development. STAT3 inhibition can be a promising treatment strategy in patients with adenomyosis.

Establishment of a novel mouse model of adenomyosis suitable for longitudinal and quantitative analysis and perinatal outcome studies.

The purpose of this study was to establish a novel mouse model of adenomyosis suitable for longitudinal and quantitative analyses and perinatal outcome studies. Using a 30 G needle, the entire uterine wall of one horn was mechanically punctured at a frequency of 100 times/1 cm (adenomyosis horn). The other horn was left unpunctured (control horn). Balb/c mice were sacrificed on day 14 (D14) or day 65 (D65) (n = 3 each). The uterus was fixed, paraffin-embedded, sliced, and stained. Lesions were detected and counted, and their volumes were measured. Cell proliferation and fibrosis were assessed by Ki67 and Masson's Trichrome staining, respectively. Blood vessels were detected using CD31 immunostaining. Some of the mice (n = 4), were mated and the date of delivery, litter size, number of implantations, and number and volume of postpartum lesions were measured. The number of lesions per horn did not differ between D14 and D65. The volume of the entire lesion was significantly greater on D65 than on D14 (p < 0.0001). The volume of the epithelial part of the lesion was significantly greater in D65 (p < 0.0001). The volume of the stromal part of the lesion was also greater on D65 (p < 0.0001). The percentage of Ki67 positive cells in the epithelial part of the lesion was significantly higher on D14 (p < 0.05). In contrast, the percentage of Ki67-positive cells in the stromal part was significantly higher on D65 (p < 0.01). Vascular density in the lesions was higher in on D65 (p < 0.05). The percentage of fibrotic area was significantly higher on D65 (p < 0.01). The date of delivery was slightly earlier than that reported for healthy mice of the same strain. The litter size was smaller than that reported in previous research. The number of implantation sites did not differ between the control and the adenomyosis horn. The number and volume of lesions did not differ between the non-pregnant and postpartum groups. This model can be applied to evaluate the pathogenesis of adenomyosis, validate the efficacy of therapeutic agents, and evaluate the effect of adenomyosis on pregnancy and vice versa.

Uterine Epithelial LIF Receptors Contribute to Implantation Chamber Formation in Blastocyst Attachment.

Recent studies have demonstrated that the formation of an implantation chamber composed of a uterine crypt, an implantation-competent blastocyst, and uterine glands is a critical step in blastocyst implantation in mice. Leukemia inhibitory factor (LIF) activates signal transducer and activator of transcription 3 (STAT3) precursors via uterine LIF receptors (LIFRs), allowing successful blastocyst implantation. Our recent study revealed that the role of epithelial STAT3 is different from that of stromal STAT3. However, both are essential for blastocyst attachment, suggesting the different roles of epithelial and stromal LIFR in blastocyst implantation. However, how epithelial and stromal LIFR regulate the blastocyst implantation process remains unclear. To investigate the roles of LIFR in the uterine epithelium and stroma, we generated Lifr-floxed/lactoferrin (Ltf)-iCre (Lifr eKO) and Lifr-floxed/antimüllerian hormone receptor type 2 (Amhr2)-Cre (Lifr sKO) mice with deleted epithelial and stromal LIFR, respectively. Surprisingly, fertility and blastocyst implantation in the Lifr sKO mice were normal despite stromal STAT3 inactivation. In contrast, blastocyst attachment failed, and no implantation chambers were formed in the Lifr eKO mice with epithelial inactivation of STAT3. In addition, normal responsiveness to ovarian hormones was observed in the peri-implantation uteri of the Lifr eKO mice. These results indicate that the epithelial LIFR-STAT3 pathway initiates the formation of implantation chambers, leading to complete blastocyst attachment, and that stromal STAT3 regulates blastocyst attachment without stromal LIFR control. Thus, uterine epithelial LIFR is critical to implantation chamber formation and blastocyst attachment.

CD206+ macrophage is an accelerator of endometriotic-like lesion via promoting angiogenesis in the endometriosis mouse model.

In endometriosis, M2 MΦs are dominant in endometriotic lesions, but the actual role of M2 MΦ is unclear. CD206 positive (+) MΦ is classified in one of M2 type MΦs and are known to produce cytokines and chemokines. In the present study, we used CD206 diphtheria toxin receptor mice, which enable to deplete CD206+ cells with diphtheria toxin (DT) in an endometriosis mouse model. The depletion of CD206+ MΦ decreased the total weight of endometriotic-like lesions significantly (p < 0.05). In the endometriotic-like lesions in the DT group, a lower proliferation of endometriotic cells and the decrease of angiogenesis were observed. In the lesions, the mRNA levels of VEGFA and TGFß1, angiogenic factors, in the DT group significantly decreased to approximately 50% and 30% of control, respectively. Immunohistochemical study revealed the expressions of VEGFA and an endothelial cell marker CD31 in lesions of the DT group, were dim compared to those in control. Also, the number of TGFß1 expressing MΦ was significantly reduced compared to control. These data suggest that CD206+ MΦ promotes the formation of endometriotic-like lesions by inducing angiogenesis around the lesions.

Sphingosine 1-Phosphate (S1P) in the Peritoneal Fluid Skews M2 Macrophage and Contributes to the Development of Endometriosis.

Sphingosine 1-phosphate (S1P), an inflammatory mediator, is abundantly contained in red blood cells and platelets. We hypothesized that the S1P concentration in the peritoneal cavity would increase especially during the menstrual phase due to the reflux of menstrual blood, and investigated the S1P concentration in the human peritoneal fluid (PF) from 14 non-endometriosis and 19 endometriosis patients. Although the relatively small number of samples requires caution in interpreting the results, S1P concentration in the PF during the menstrual phase was predominantly increased compared to the non-menstrual phase, regardless of the presence or absence of endometriosis. During the non-menstrual phase, patients with endometriosis showed a significant increase in S1P concentration compared to controls. In vitro experiments using human intra-peritoneal macrophages (MΦ) showed that S1P stimulation biased them toward an M2MΦ-dominant condition and increased the expression of IL-6 and COX-2. An in vivo study showed that administration of S1P increased the size of the endometriotic-like lesion in a mouse model of endometriosis.

Acquired contractile ability in human endometrial stromal cells by passive loading of cyclic tensile stretch.

The uterus plays an important and unique role during pregnancy and is a dynamic organ subjected to mechanical stimuli. It has been reported that infertility occurs when the peristalsis is prevented, although its mechanisms remain unknown. In this study, we found that mechanical strain mimicking the peristaltic motion of the uterine smooth muscle layer enabled the endometrial stromal cells to acquire contractility. In order to mimic the peristalsis induced by uterine smooth muscle cells, cyclic tensile stretch was applied to human endometrial stromal cells. The results showed that the strained cells exerted greater contractility in three-dimensional collagen gels in the presence of oxytocin, due to up-regulated alpha-smooth muscle actin expression via the cAMP signaling pathway. These in vitro findings underscore the plasticity of the endometrial stromal cell phenotype and suggest the possibility of acquired contractility by these cells in vivo and its potential contribution to uterine contractile activity. This phenomenon may be a typical example of how a tissue passively acquires new contractile functions under mechanical stimulation from a neighboring tissue, enabling it to support the adjacent tissue's functions.

IL-33 Exacerbates Endometriotic Lesions via Polarizing Peritoneal Macrophages to M2 Subtype.

In endometriosis, M2 macrophages (MΦ) are dominant and promote the development of endometriosis lesions. However, the factor(s) which induces M2 MΦ are unknown. In the present study, we focused on interleukin (IL)-33, known as an alarmin and investigated its expression and its role in endometriosis, especially from the point of the relevance with MΦ. The expression of IL-33 in endometriosis lesions was examined by immunohistochemistry. The cystic fluid of ovarian cysts/tumors was obtained and used to measure IL-33 concentration. Endometriotic stromal cells (ESC) and MΦ derived from patients were used for in vitro experiments. IL-33 was detected in the epithelium and stromal cells of endometriotic lesions. The mean IL-33 concentration in the cystic fluid of endometriomas was significantly higher than that in non-endometriomas (2.2 ng/ml vs. 0.02 ng/ml, P < 0.01). IL-1ß induced IL-33 mRNA expression in ESC via p38 MAPK activation. With IL-33 stimulation, peritoneal MΦ polarized to M2 MΦ and produced IL-1ß mRNA with a 2.2-fold increase, which was negated with soluble ST2, a decoy receptor of IL-33. IL-33, derived from endometriotic lesions, stimulated MΦ to produce IL-1ß, which results in increasing IL-33 production in ESC. This cycle may continue to exacerbate the endometriotic lesions.