Healthy Endometrium Research Articles

Endometriosis development in relation to hypoxia: a murine model study.

Endometriosis, due to its ambiguous symptoms, still remains one of the most difficult female diseases to treat, with an average diagnosis time of 7-9years. The changing level of hypoxia plays an important role in a healthy endometrium during menstruation and an elevated expression of the hypoxia-inducible factor 1-alpha (HIF-1α) has been demonstrated in ectopic endometria. HIF-1α mediates the induction of proangiogenic factors and the development of angiogenesis is a critical step in the establishment and pathogenesis of endometriosis. Although the inhibition of angiogenesis has been proposed as one of the actionable therapeutic modalities, vascular normalization and re-oxygenation may become a possible new approach for therapeutic intervention. Our goal was to investigate whether a selected murine model of endometriosis would be suitable for future studies on new methods for treating endometriosis. Non-invasive, high-resolution ultrasound-monitored observation was selected as the preclinical approach to obtain imaging of the presence and volume of the endometriotic-like lesions. The EF5 (2-(2-Nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide) compound that selectively binds to reduced proteins in hypoxic cells was used for hypoxia detection. The expression of Pten and other crucial genes linking endometriosis and hypoxia were also assessed. Using EF5, a pentafluorinated derivative of the 2-nitroimidazole that is metabolically reduced by oxygen-inhibitable nitroreductase, we confirmed that hypoxia did develop in the selected model and was detected in uterine and ectopic endometriotic lesions. Moreover, the changes in oxygen tension also influenced the expression level of significant genes related to endometriosis, like Pten, Trp53, Hif1a, Epas1, and Vegfa. Their strong modulation evidenced here is indicative of model reliability. Using high-resolution ultrasound-based imaging, we present a non-invasive method of visualization that enables the detection and observation of lesion evolution throughout the duration of the experiment, which is fundamental for further preclinical studies and treatment evaluation. The selected model and method of visualization appear to be suitable for the study of new treatment strategies based on hypoxia alleviation and blood flow restoration.

Elevated MMP-9, Survivin, TGB1 and Downregulated Tissue Inhibitor of TIMP-1, Caspase-3 Activities are Independent of the Low Levels miR-183 in Endometriosis.

This study aimed to measure the correlation between miR-183 and gene expression that regulates apoptosis and adhesion mechanism that may be linked to the pathogenesis of endometriosis. Forty-four subjects, including 22 control subjects, participated in this study. We collected ectopic endometriosis and endometrial samples. For the control, the sample was taken from endometrial tissue through pipelle biopsy. RNA was extracted from all tissues using RNA mini kit, and the expression was assessed using quantitative-real time PCR. Relative mRNA and miRNA expression were presented using the formula of the Livak method. The data were statistically analyzed using GraphPad Prism 8. The expression of Caspase-3, Survivin, Integrin β1 (ITGB1), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) (adhesion- and apoptosis-related gene) were calculated using the relative expression method. We found significant differences in Caspase-3, Survivin, ITGB1, MMP-9, and TIMP-1 expression between ectopic endometriosis tissues of women with endometriosis compared to healthy endometrium. MMP-9, Survivin, and ITGB1 was significantly increased in the endometriosis group, while Caspase-3, TIMP-1, and miR-183 were significantly reduced in the endometriosis group. No correlation was found between the expression level of miR-183 and Caspase3, Survivin, ITGB1, and Cadherin in both tissue types. Despite the difference in expression levels of miR-183 and associated adhesion- and apoptosis-related genes, there was no significant association between miR-183 with specific adhesion and apoptosis genes in endometriosis tissue.

The Interplay between Oxidative Stress and Sphingolipid Metabolism in Endometrial Cancer

Endometrial cancer is one of the most common malignancies in women. Sphingolipids, a group of lipids, play a key role in cancer biology. Cancer cells often exhibit abnormal redox homeostasis characterized by elevated levels of reactive oxygen species (ROS). Emerging evidence suggests that ceramides are involved in inhibiting proliferation and inducing apoptosis through ROS production. However, there is no data on the relationship between sphingolipid metabolism and oxidative status in endometrial cancer. The present study aims to assess the content of individual sphingolipids and oxidative status in healthy women and those with endometrial cancer. Sphingolipid analysis was performed using mass spectrometry. Total oxidative status (TOS) and total antioxidant capacity (TAC) were assessed colorimetrically. Our results showed a significant increase in the levels of all measured sphingolipids in cancer tissues compared to healthy endometrium. Additionally, a significant decrease in the S1P/ceramide ratio (sphingolipid rheostat) was observed in cancer patients, particularly for C14:0-Cer, C16:0-Cer, C18:1-Cer, C22:0-Cer, and C24:0-Cer. Furthermore, increased TOS and decreased TAC were found in cancer patients compared to healthy women. Significant correlations were observed between the levels of individual sphingolipids and oxidative status, with the strongest correlation noted between C22:0-Cer and TOS (r = 0.64). We conclude that endometrial cancer is characterized by profound changes in sphingolipid metabolism, contributing to oxidative dysregulation and tumor progression.

Expression of Endometrial Receptivity Markers throughout the Menstrual Cycle in Women with and without Uterine Adenomyosis.

Background/Objectives: While it is known that adenomyosis is associated with poor reproductive outcomes, the underlying mechanisms are unclear, and to date, there is no standard treatment protocol for these patients. Endometrium from adenomyosis patients is characterized by several abnormalities, potentially resulting in impaired receptivity and subsequent implantation failure. Methods: Endometrial biopsies were collected from 26 women with adenomyosis and 26 control subjects. Immunohistochemistry was performed to evaluate the expression of markers of endometrial receptivity, namely the progesterone receptor (PR), glycodelin, leukemia inhibitory factor (LIF), homeobox A10 (HOXA10), integrin beta chain beta 3 (integrin β3) and osteopontin. Scanning electron microscopy was used to observe pinopodes on the surface of mid-secretory endometrial epithelium. Results: PR, LIF and osteopontin expression were all found to be weaker in secretory-phase stroma from adenomyosis patients than in healthy controls. HOXA10 expression was decreased in adenomyosis during the secretory phase, and also the proliferative phase, where it reached statistical significance in both epithelial and stromal compartments. Glycodelin and integrin β3 levels did not differ between diseased and healthy tissues in any of the cycle phases. Pinopodes were fewer and at later developmental stages in adenomyosis compared to those on the surface of healthy endometrium from the same time period of the menstrual cycle. Conclusions: Endometrium from adenomyosis patients is characterized by abnormal expression of various receptivity markers. The stromal compartment appears to be affected most, showing reduced expression of PR, LIF and osteopontin in the secretory phase and lower levels of HOXA10 during both proliferative and secretory phases. Decreased receptivity due to impaired stromal decidualization may contribute to poor reproductive outcomes in adenomyosis patients.

Single-cell transcriptomic analysis of immune cell dynamics in the healthy human endometrium

The microenvironment of the endometrial immune system is crucial to the success of placental implantation and healthy pregnancy. However, the functionalities of immune cells across various stages of the reproductive cycle have yet to be fully comprehended. To address this, we conducted advanced bioinformatic analysis on 230,049 high-quality single-cell transcriptomes from healthy endometrial samples obtained during the proliferative, secretory, early pregnancy, and late pregnancy stages. Our investigation has unveiled that proliferative natural killer (NK) cells, a potential source of endometrial NK cells, exhibit the most robust proliferative and differentiation potential during non-pregnant stages. We have also identified similar differentiation trajectories of NK cells originating from proliferative NK cells across four stages. Notably, during early pregnancy, NK cells demonstrate the highest oxidative phosphorylation metabolism activity, and, in conjunction with macrophages and T cells, exhibit the strongest type II interferon response. With spatial transcriptome data, we have discerned that the most robust immune-non-immune interactions are associated with the promotion and inhibition of cell proliferation, differentiation and migration during four stages. Furthermore, we have compiled lists of stage-specific risk genes implicated in reproductive diseases, which hold promise as potential disease biomarkers. Our study provides insights into the dynamics of the endometrial immune microenvironment during different reproductive cycle stages, thus serving as a reference for detecting pathological changes during pregnancy.

Cytoskeletal and inter-cellular junction remodelling in endometrial organoids under oxygen-glucose deprivation: a new potential pathological mechanism for thin endometria.

What is the pathological mechanism involved in a thin endometrium, particularly under ischaemic conditions? Endometrial dysfunction in patients with thin endometrium primarily results from remodelling in cytoskeletons and cellular junctions of endometrial epithelial cells under ischemic conditions. A healthy endometrium is essential for successful embryo implantation and subsequent pregnancy; ischemic conditions in a thin endometrium compromise fertility outcomes. We recruited 10 patients with thin endometrium and 15 patients with healthy endometrium. Doppler ultrasound and immunohistochemical results confirmed the presence of insufficient endometrial blood perfusion in patients with thin endometrium. Organoids were constructed using healthy endometrial tissue and cultured under oxygen-glucose deprivation (OGD) conditions for 24 h. The morphological, transcriptomic, protein expression, and signaling pathway changes in the OGD organoids were observed. These findings were validated in both thin endometrial tissue and healthy endometrial tissue samples. Endometrial thickness and blood flow were measured during the late follicular phase using transvaginal Doppler ultrasound. Endometrial tissue was obtained via hysteroscopy. Fresh endometrial tissues were used for the generation and culture of human endometrial organoids. Organoids were cultured in an appropriate medium and subjected to OGD to simulate ischemic conditions. Apoptosis and cell death were assessed using Annexin-V/propidium iodide staining. Immunofluorescence analysis, RNA sequencing, western blotting, simple westerns, immunohistochemistry, and electron microscopy were conducted to evaluate cellular and molecular changes. Patients with thin endometrium showed significantly reduced endometrial thickness and altered blood flow patterns compared to those with healthy endometrium. Immunohistochemical staining revealed fewer CD34-positive blood vessels and glands in the thin endometrium group. Organoids cultured under OGD conditions exhibited significant morphological changes, increased apoptosis, and cell death. RNA-seq identified differentially expressed genes related to cytoskeletal remodeling and stress responses. OGD induced a strong cytoskeletal reorganization, mediated by the RhoA/ROCK signaling pathway. Additionally, electron microscopy indicated compromised epithelial integrity and abnormal cell junctions in thin endometrial tissues. Upregulation of hypoxia markers (HIF-1α and HIF-2α) and activation of the RhoA/ROCK pathway were also observed in thin endometrial tissues, suggesting ischemia and hypoxia as underlying mechanisms. none. The study was conducted in an in vitro model, which may not fully replicate the complexity of in vivo conditions. This research provides a new three-dimensional in vitro model of thin endometrium, as well as novel insights into the pathophysiological mechanisms of endometrial ischaemia in thin endometrium, offering potential avenues for identifying therapeutic targets for treating fertility issues related to thin endometrium. This study was supported by the National Natural Science Foundation of China (81925013); National Key Research and Development Project of China (2022YFC2702500, 2021YFC2700303, 2021YFC2700601); the Capital Health Research and Development Project (SF2022-1-4092); the National Natural Science Foundation of China (82288102, 81925013, 82225019, 82192873); Special Project on Capital Clinical Diagnosis and Treatment Technology Research and Transformation Application (Z211100002921054); the Frontiers Medical Center, Tianfu Jincheng Laboratory Foundation(TFJC2023010001). The authors declare that no competing interests exist.

Excessive proliferating cell nuclear antigen attenuates endometrial adhesive capacity and decidualization in patients with recurrent implantation failure.

Does the expression of proliferating cell nuclear antigen (PCNA) in the endometrium regulate endometrial receptivity in patients with recurrent implantation failure (RIF)? A high abundance of PCNA attenuates endometrial adhesive capacity and decidualization in patients with RIF. Aberrant expression of PCNA has been discovered in multiple infertility-related disorders. However, the expression pattern and role of PCNA in the establishment of endometrial receptivity and endometrial decidualization in patients with RIF remain unclear. We analysed the expression of PCNA in mid-secretory endometrial tissues from 24 patients with RIF and 24 healthy women. Additionally, PCNA expression levels were measured in proliferative and mid-secretory phase endometrial tissue samples from women with regular menstrual cycles and in decidual tissue samples taken from ten women during normal early pregnancy (n = 10 per phase for each group). The function and regulatory mechanisms of PCNA in endometrial adhesive capacity and endometrial decidualization were investigated using BeWo spheroids, Ishikawa cells, and human endometrial stromal cells (HESCs). The expression of PCNA in mid-secretory endometrial tissues of patients with RIF and women with normal endometrium and in endometrial tissue at different stages of the menstrual cycle and in decidualized tissues was analysed by RT-qPCR, western blot, and immunohistochemistry staining (IHC). Furthermore, the number of BeWo spheroids directly attached to the Ishikawa cell monolayers, and the potential molecular mechanisms involved, were compared between cells overexpressing PCNA and a control group. Additionally, the effect and regulatory mechanisms of PCNA on the decidualization of HESCs in vitro were investigated. Our findings indicated that the abundance of PCNA was dramatically greater in mid-secretory endometrial tissues from patients with RIF than in those from women with healthy endometrium. The expression of PCNA increased in the proliferative phase of the menstrual cycle but decreased gradually in the mid-secretory phase and in decidual tissues. Interestingly, PCNA was expressed in both human endometrial epithelial cells (HEECs) and HESCs. In Ishikawa cells, PCNA overexpression dramatically reduced the endometrial adhesive capacity by inhibiting the expression of adhesion molecules (E-cadherin and integrin β3) and activating the FAK/paxillin signalling pathway. Furthermore, in HESCs, PCNA overexpression attenuated endometrial decidualization by activating the AKT/β-catenin signalling pathway and increasing tight junctions between cells by upregulating ZO-1 and occludin expression. In addition, PCNA-ELAVL1 interactions were confirmed by coimmunoprecipitation in decidualized HESCs. N/A. The functional analysis of PCNA was limited by the number of human endometrial tissues. A larger sample size is required to further explore the potential roles of PCNA during embryo implantation. Moreover, the present results should be taken with caution, as only a few of the embryos that were transferred in RIF patients population underwent preimplantation genetic testing for embryonic chromosome aneuploidies (PGT-A), despite embryo ploidy testing being significant in the diagnosis of unexplained RIF. High PCNA expression attenuates endometrial adhesive capacity and decidualization in patients with RIF. These findings provide new insights into the potential mechanisms underlying the occurrence of implantation failure. This work was supported by the National Natural Science Foundation of China (82101698), Shandong Provincial Natural Science Foundation (ZR2021MH012), and the Science and Technology Plan of Yantai (2023YD021 and 2022YD031). The authors have no conflicts of interest to disclose. N/A.

Homeobox regulator Wilms Tumour 1 is displaced by androgen receptor at cis-regulatory elements in the endometrium of PCOS patients.

Decidualisation, the process whereby endometrial stromal cells undergo morphological and functional transformation in preparation for trophoblast invasion, is often disrupted in women with polycystic ovary syndrome (PCOS) resulting in complications with pregnancy and/or infertility. The transcription factor Wilms tumour suppressor 1 (WT1) is a key regulator of the decidualization process, which is reduced in patients with PCOS, a complex condition characterized by increased expression of androgen receptor in endometrial cells and high presence of circulating androgens. Using genome-wide chromatin immunoprecipitation approaches on primary human endometrial stromal cells, we identify key genes regulated by WT1 during decidualization, including homeobox transcription factors which are important for regulating cell differentiation. Furthermore, we found that AR in PCOS patients binds to the same DNA regions as WT1 in samples from healthy endometrium, suggesting dysregulation of genes important to decidualisation pathways in PCOS endometrium due to competitive binding between WT1 and AR. Integrating RNA-seq and H3K4me3 and H3K27ac ChIP-seq metadata with our WT1/AR data, we identified a number of key genes involved in immune response and angiogenesis pathways that are dysregulated in PCOS patients. This is likely due to epigenetic alterations at distal enhancer regions allowing AR to recruit cofactors such as MAGEA11, and demonstrates the consequences of AR disruption of WT1 in PCOS endometrium.

Enhancing endometrial receptivity in FET cycles: exploring the influence of endometrial and subendometrial blood flow along with endometrial volume.

Fetal health and a receptive and healthy endometrium are two essential factors in achieving successful implantation. If the endometrium is unreceptive, postponing the transfer cycle to a suitable time can enhance the chances of pregnancy. This study aims to assess the impact of endometrial and sub-endometrial blood flows measured by Doppler ultrasound, as well as endometrial volume, on endometrial receptivity in frozen embryo transfer (FET) cycles. 112 patients with a mean age of 33.93 ± 4.93 years underwent in vitro fertilization (IVF). Serum β-hCG level was used to confirm pregnancy, and among the participants, 50 (44.6%) achieved pregnancy after IVF. The study results revealed a significant difference in endometrial blood flow between the pregnant and non-pregnant groups, with a higher pregnancy rate observed in participants exhibiting multi-focal and spare endometrial blood flows (p < 0.05). Furthermore, there was a notable association between endometrial blood flow and pregnancy outcome, as indicated by higher ongoing pregnancy rates in those with multi-focal and spare endometrial blood flows (p < 0.05). However, no significant differences were observed in endometrial variables such as volume, length, width, thickness, and pattern between the pregnant and non-pregnant groups. Additionally, contextual parameters showed no significant relationship with pregnancy outcome (p > 0.05). The study also found that endometrial measurement indices did not have a significant impact on pregnancy outcomes, with no significant differences observed between the groups (p > 0.05). In conclusion, endometrial blood flow is crucial for a successful pregnancy after IVF, while the predictive value of the endometrial volume is limited for pregnancy outcomes.

Sphingosine 1-phosphate signaling axis mediates neuropeptide S-induced invasive phenotype of endometriotic cells.

Endometriosis is a chronic gynecological syndrome characterized by endometrial cell invasion of the extra-uterine milieu, pelvic pain and infertility. Treatment relies on either symptomatic drugs or hormonal therapies, even though the mechanism involved in the onset of endometriosis is yet to be elucidated. The signaling of sphingolipid sphingosine 1-phosphate (S1P) is profoundly dysregulated in endometriosis. Indeed, sphingosine kinase (SK)1, one of the two isoenzymes responsible for S1P biosynthesis, and S1P1, S1P3 and S1P5, three of its five specific receptors, are more highly expressed in endometriotic lesions compared to healthy endometrium. Recently, missense coding variants of the gene encoding the receptor 1 for neuropeptide S (NPS) have been robustly associated with endometriosis in humans. This study aimed to characterize the biological effect of NPS in endometriotic epithelial cells and the possible involvement of the S1P signaling axis in its action. NPS was found to potently induce cell invasion and actin cytoskeletal remodeling. Of note, the NPS-induced invasive phenotype was dependent on SK1 and SK2 as well as on S1P1 and S1P3, given that the biological action of the neuropeptide was fully prevented when one of the two biosynthetic enzymes or one of the two selective receptors was inhibited or silenced. Furthermore, the RhoA/Rho kinase pathway, downstream to S1P receptor signaling, was found to be critically implicated in invasion and cytoskeletal remodeling elicited by NPS. These findings provide new information to the understanding of the molecular mechanisms implicated in endometriosis pathogenesis, establishing the rationale for non-hormonal therapeutic targets for its treatment.

Expression of oestrogen and progesterone receptor and intermediate filament proteins in the oviduct of mares with endometrosis

Equine endometrosis is one of the major causes of equine infertility, in the course of which periglandular fibrosis signs occur in the endometrium. As an oviduct is a key place of early embryo development, we hypothesized that loss of contact between mucosal cells and perturbation in hormonal action may coexist in the uterus and oviducts. Thus, this study aimed to investigate the expression of the intermediate filaments (vimentin and desmin) as well as the estrogen receptor alpha (ERα) and progesterone receptor A (PRA) in the stroma and epithelia of endometrium and oviduct in healthy mares and these with endometrosis. Out of 56 culled-in slaughterhouse mare endometrium samples were annotated in two groups (i) healthy endometrium (n=26) and endometrium with signs of moderate and severe endometrosis (n=20). The expression of vimentin, desmin, ERα, and PRA was investigated immunohistochemically and compared between the above groups as well as between the phase of the estrous cycle. The expression of both vimentin and desmin was higher in the endometrial stroma of endometrosis group compared to healthy endometrium. The expression of ERα was higher in the healthy endometrial stroma and luminal epithelium during the follicular phase than luteal, however, no differences were noted in endometrium of mares with endometrosis. Moreover, PRA expression was significantly higher in the stoma oviduct during the follicular phase than luteal. It seems possible that mucosal cells through their altered interactions may support the occurrence of moderate and severe endometrosis. In addition, the oviduct appears to be less sensitive to hormonal changes than the uterus. The changed expression of intermediate filaments and steroid hormones may be some of the leading factors which can contribute to the oviduct functional status in endometrosis.

17β-Estradiol mediates TGFBR3/Smad2/3 signaling to attenuate the fibrosis of TGF-β1-induced bovine endometrial epithelial cells via GPER.

Abnormal function and fibrosis of endometrium caused by cows' endometritis pose difficult implantation of embryos and uterine cavity adhesions. 17β-Estradiol (E2) serves as the most effective aromatized estrogen, and its synthetase and receptors have been detected in the endometrium. Studies have demonstrated the positive role of estrogen in combating pathological fibrosis in diverse diseases. However, it is still unknown whether E2 regulates endometrium fibrosis in bovine endometritis. Herein, we evaluated the expression patterns of transforming growth factor-β1 (TGF-β1), epithelial-mesenchymal transformation (EMT)-related proteins (α-SMA, vimentin N-cadherin and E-cadherin), cytochrome P450 19A1 (CYP19A1), and G protein-coupled estrogen receptor (GPER) in bovine healthy endometrium and Inflammatory endometrium. Our data showed that the inflamed endometrium presented low CYP19A1 and GPER expression, and significantly higher EMT process versus the normal tissue. Moreover, we established a TGF-β1-induced fibrosis model in BEND cells, and found that E2 inhibited the EMT process of BEND cells in a dose-dependent manner. The anti-fibrotic effect of E2 was blocked by the GPER inhibitor G15, but not the estrogen nuclear receptors (ERs) inhibitor ICI182780. Moreover, the GPER agonist G1 inhibited fibrosis and Smad2/3 phosphorylation but increased the expression of TGFBR3 in BEND cells. Transfection with TGFBR3 small interfering RNA blocked the effect of G1 on fibrosis of BEND cells and upregulated the expression of P-Smad2/3. Our in vivo data also showed that E2 and G1 affected uterus fibrosis in mice endometritis model caused by LPS, which was associated with the inhibition of TGFBR3/Smad2/3 signaling. In conclusion, our data implied that E2 alleviates the fibrosis of TGF-β1-induced BEND cells, which is associated with the GPER mediation of TGFBR3/Smad2/3 signaling.

Matrix scaffolds for endometrium-derived organoid models.

The uterus-lining endometrium is essential to mammalian reproduction, receiving and accommodating the embryo for proper development. Despite its key role, mechanisms underlying endometrial biology (menstrual cycling, embryo interaction) and disease are not well understood. Its hidden location in the womb, and thereby-associated lack of suitable research models, contribute to this knowledge gap. Recently, 3D organoid models have been developed from both healthy and diseased endometrium. These organoids closely recapitulate the tissue's epithelium phenotype and (patho)biology, including in vitro reproduction of the menstrual cycle. Typically, organoids are grown in a scaffold made of surrogate tissue extracellular matrix (ECM), with mouse tumor basement membrane extracts being the most commonly used. However, important limitations apply including their lack of standardization and xeno-derivation which strongly hinder clinical translation. Therefore, researchers are actively seeking better alternatives including fully defined matrices for faithful and efficient growth of organoids. Here, we summarize the state-of-the-art regarding matrix scaffolds to grow endometrium-derived organoids as well as more advanced organoid-based 3D models. We discuss remaining shortcomings and challenges to advance endometrial organoids toward defined and standardized tools for applications in basic research and translational/clinical fields.

Endometrial proteomic profile of patients with repeated implantation failure.

Successful embryo implantation, is the initiating step of pregnancy, relies on not only the high quality of the embryo but also the synergistic development of a healthy endometrium. Characterization and identification of biomarkers for the receptive endometrium is an effective method for increasing the probability of successful embryo implantation. Endometrial tissues from 22 women with a history of recurrent implantation failure (RIF) and 19 fertile controls were collected using biopsy catheters on 7-9 days after the peak of luteinizing hormone. Differentially expressed proteins (DEPs) were identified in six patients with RIF and six fertile controls using isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomics analysis. Two hundred and sixty-three DEPs, including proteins with multiple bioactivities, such as protein translation, mitochondrial function, oxidoreductase activity, fatty acid and amino acid metabolism, were identified from iTRAQ. Four potential biomarkers for receptive endometrium named tubulin polymerization-promoting protein family member 3 TPPP3, S100 Calcium Binding Protein A13 (S100A13), 17b-hydroxysteroid dehydrogenase 2 (HSD17B2), and alpha-2-glycoprotein 1, zinc binding (AZGP1) were further verified using ProteinSimple Wes and immunohistochemical staining in all included samples (n=22 for RIF and n=19 for controls). Of the four proteins, the protein levels of TPPP3 and HSD17B2 were significantly downregulated in the endometrium of patients with RIF. Poor endometrial receptivity is considered the main reason for the decrease in pregnancy success rates in patients suffering from RIF. iTRAQ techniques based on isotope markers can identify and quantify low abundance proteomics, and may be suitable for identifying differentially expressed proteins in RIF. This study provides novel evidence that TPPP3 and HSD17B2 may be effective targets for the diagnosis and treatment of non-receptive endometrium and RIF.

WS02.01 Decreased fertility in female cystic fibrosis patients: peering into the endometrial factor using cutting-edge organoid models

Female CF patients suffer from sub-to infertility, often facing problems to become pregnant. Underlying reasons remain understudied. In particular, it is largely unknown whether dysfunction of the endometrium is involved, the womb’s inner lining and key tissue for embryo implantation and development. This gap is mainly due to lack of appropriate study models. Therefore, we develop and apply tissue-mimicking organoid models to indetail decipher molecular and functional aberrations in fertility-deficient CF endometrium as compared to healthy (fertile) endometrium. First, we established endometrial organoids (EMO) from the Cftrtm1Eur mouse model. These organoids show a smaller lumen than wildtype (WT) EMO, and do not swell in the FIS assay, both validating the CFTR defect. Currently, we are comparing expression of endometrial functionality/fertility markers in CF versus WT EMO, as well as their responsiveness to estrogen (E2) and progesterone (P4), which in vivo regulate the estrous cycle. Second, we develop(ed) organoids from CF patient endometrium. Before, we have shown that EMO from healthy endometrium can reliably reproduce all menstrual cycle phases under defined E2/P4 exposure. Currently, we are deciphering whether and how menstrual cycle phases, including the receptivity stage, are different between CF and healthy EMO. We already observed dissimilarities in the proliferative (E2) and secretory (P4) phase, such as increased apoptosis and decreased fertility marker expression, respectively. Taken together, we establish(ed) organoid models from CF endometrium as novel and powerful tools to gain insight into the endometrial factor in CF fertility deficiency. Importantly, the organoids will be highly apt to explore the impact of new-era CFTR modulators on the endometrium, at present unknown. Moreover, our study has the potential to reveal paths toward restoring reproductive fitness in CF patients, which can be tested using the organoids as (drug) screening platform.

Endometrial fibrosis in mares: Picrosirius Red and Collagen-2 and 3

In mares, endometrial fibrosis results from abnormal collagen deposition in the stroma and around the endometrial glands. The pathogenesis of endometrial fibrosis remains unknown, but the different types of collagens are a fundamental part of the process. The Picrosirius Red (PSR) staining is widely studied and necessary for collagen fiber and tissue remodeling. The present study aimed to determine the collagen deposition and the gene expression of collagen-2(COL-2) and collagen-3(COL-3) in the endometrium of mares with different degrees of fibrosis. Cyclic mares (n = 34) with a mean age of 14 ± 6.4 years old were used. A uterine biopsy from each mare was obtained at diestrus (D5–D10). Mares were grouped according to the degree of uterine fibrosis described by Kenney (1978): Grade I (n = 12), Grade II (n = 12), and Grade III (n = 10). Collagen in the equine endometrium was morphometrically quantified under PSR staining. The morphometric quantification of the images was performed from each sample after digital microphotographs were taken at 200x magnification, processed, and evaluated using the ImageJ 1.52a software. COL-2 and COL-3 expression was performed using qPCR. Grades were considered independent factors. Collagen-stained area and transcript expression were considered dependent factors. Data were analyzed with ANOVA andt-test. A Pearson correlation was performed between age and collagen deposition. The percentage of tissue collagen area stained with PSR revealed a significant increase between all groups in collagen deposition according to the degree of fibrosis: Grade I (11.7 ± 1.4%), Grade II (17.8 ± 1.3%), and Grade III (24.1 ± 1.9%). Age and the percentage of collagen deposited in the endometrial tissue correlated (r = 0.5) (P = 0.015). Grade II samples presented higher expression of COL-2 transcripts compared to Grade I (P = 0.026) and Grade III (P = 0.003). However, COL-3 did not show differences between groups. This study agrees with other studies that indicate that the worsening of degenerative changes coincides with advanced mare age. Sample evaluations emphasizing degenerative changes rely on an experienced evaluator, while the PSR, followed by computerized analysis, presents quantitative data. In conclusion, the increase in PSR analysis in Grade II and Grade III mares compared to Grade I demonstrates that this technique could play an important role in routine analyses for the detection, quantification, and dynamics of collagen in specific tissues. The study revealed that COL-2 might be involved in the progression and differentiation of healthy endometrium into an endometrium with severe fibrosis.

MSX1-expression during the different phases in healthy human endometrium

PurposeThe human endometrium consists of different layers (basalis and functionalis) and undergoes different phases throughout the menstrual cycle. In a former paper, our research group was able to describe MSX1 as a positive prognosticator in endometrial carcinomas. The aim of this study was to examine the MSX1 expression in healthy endometrial tissue throughout the different phases to gain more insight on the mechanics of MSX-regulation in the female reproductive system.Materials and methodsIn this retrospective study, we investigated a total of 17 normal endometrial tissues (six during proliferative phase and five during early and six during late secretory phase). We used immunohistochemical staining and an immunoreactive score (IRS) to evaluate MSX1 expression. We also investigated correlations with other proteins, that have already been examined in our research group using the same patient collective.ResultsMSX1 is expressed in glandular cells during the proliferative phase and downregulated at early and late secretory phase (p = 0.011). Also, a positive correlation between MSX1 and the progesterone-receptor A (PR-A) (correlation coefficient (cc) = 0.0671; p = 0.024), and the progesterone receptor B (PR-B) (cc = 0.0691; p = 0.018) was found. A trend towards negative correlation was recognized between MSX1 and Inhibin Beta-C-expression in glandular cells (cc = − 0.583; p-value = 0.060).ConclusionMSX1 is known as a member of the muscle segment homeobox gene family. MSX1 is a p53-interacting protein and overexpression of homeobox MSX1 induced apoptosis of cancer cells. Here we show that MSX1 is expressed especially in the proliferative phase of glandular epithelial tissue of the normal endometrium. The found positive correlation between MSX1 and progesterone receptors A and B confirms the results of a previous study on cancer tissue by our research group. Because MSX1 is known to be downregulated by progesterone, the found correlation of MSX1 and both PR-A and -B may represent a direct regulation of the MSX1 gene by a PR-response element. Here further investigation would be of interest.

Effects of uterine polyps on embryo implantation in IVF cycles

Embryo implantation requires healthy uterine endometrium for natural or assisted reproductive technology conception. However, in presence of any endometrial anatomical abnormality or disease, implantation is affected. Uterine or endometrial polyps are over growths of endometrial cells that extend into the uterine cavity. They are usually noncancerous. There can be one or many polyps. They range in size from a few millimeters to several centimeters or larger. They may cause vaginal bleeding in between periods, heavy periods, frequent or unpredictable periods and infertility. The objective of this study was to find out effects of endometrial polyps on embryo implantation in assisted reproductive technology cycles of Saudi women being treated at an infertility clinic. This was a case-control study. The participants were in ratio of 5:1 i.e., for every 5 patients there was one control. The polyp diagnosis was carried out with ultrasound and endometrial biopsy. We observed high incidence of implantation failure in patients with uterine polyps as compared to that in the control patients. The results of this study indicated that the presence of endometrial polyps is a risk factor for infertility and failure of conception after in vitro fertilization.

Investigation of hub ferroptosis-related genes and the immune landscape in recurrent pregnancy loss and unexplained infertility using bioinformatics analysis.

Recurrent pregnancy loss (RPL) and unexplained infertility (UI) are common pregnancy disorders that affect women's physical and mental health and lack effective treatment. Endometrial factors are one factor that leads to RPL. The latest research indicates that ferroptosis and immunity are closely related to the normal physiological function of the endometrium and may play a role in the pathogenesis of RPL and UI. Therefore, the present study analyzed the relationship between ferroptosis genes and immune infiltration in RPL and UI. We downloaded the GSE165004 dataset and analyzed differences in ferroptosis-related genes (FRGs) between RPL and UI patients and healthy controls. Hub differentially expressed ferroptosis-related genes (DE-FRGs) were screened using the LASSO algorithm, the SVM-RFE algorithm and the protein-protein interaction (PPI) network. Differences in immune infiltration between healthy endometrium and RPL and UI endometrium was analyzed, and the relationship between hub DE-FRGs and immune cell infiltration was examined. We extracted 409 FRGs and identified 36 up-regulated and 32 down-regulated DE-FRGs in RPL and UI. Twenty-one genes were screened using the LASSO regression algorithm, and 17 genes were screened using the SVM-RFE algorithm. We intersected the LASSO genes, SVM-RFE genes and PPI network proteins to obtain 5 hub DE-FRGs. Gene set enrichment analysis (GSEA) functional enrichment analysis results indicated that the cytokine-cytokine receptor interaction signaling pathway was the common pathway for hub DE-FRGs. T follicular helper cells were highly infiltrated in RPL and UI, and M1 and M2 macrophages were highly infiltrated. The expression levels of MAPK1 and RELA positively correlated with T follicular helper cells. Ferroptosis-related genes may disrupt endometrial functions and signaling pathways and lead to the occurrence of RPL and UI.

Restoring Fertility of Patients with Severe Asherman's Syndrome in the Office Setting: A Step-by-Step Recipe for Success

To describe an effective in-office hysteroscopic strategy to restore fertility of patients with severe Asherman's syndrome. A step-by-step video demonstration of the technique with an emphasis on the key portions of the procedure. A detailed narrated description of the steps is provided. Tertiary care University Hospital. Three patients were managed by hysteroscopy performed in the office setting without anesthesia. Case 1 is a 34-year-old woman with obstetrical history of first-trimester incomplete abortion treated with Dilation and Curettage (D&C), followed by a tubal ectopic pregnancy treated with laparoscopic partial salpingectomy and a subsequent pregnancy on the tubal stump treated with uterine artery embolization. Case 2 is a 40-year-old woman with history of tubal ectopic pregnancy treated with salpingectomy, a surgical first-trimester voluntary termination of pregnancy with D&C and a full term vaginal delivery complicated with retained products of conception that were removed with D&C. Case 3 is a 35-year-old woman with two previous first-trimester spontaneous miscarriages both treated with D&C. Case 1 and 3 were treated using miniaturized mechanical instruments only; in case 2, miniaturized mechanical instruments and the 15 Fr bipolar mini-resectoscope were used. Preoperative 2D and 3D ultrasound were used to predict the complexity of the cases and to guide the surgeon during the procedure. Intrauterine lysis of adhesions was concluded when both tubal ostia were visualized, and the uterine cavity was determined to have adequate shape and volume. At the end of the procedures, hyaluronic acid-based gel was applied to prevent new intrauterine adhesion formation. Two weeks after the initial procedure, a second look diagnostic hysteroscopy was performed. Only one patient (#1) needed additional lysis of adhesions; in this case, at the end of the procedure, a Word catheter was inserted as a barrier method for the prevention of adhesion formation. Eight weeks later, the word catheter was removed, and additional lysis of adhesions was performed. All the surgical procedures were performed without complication, and a healthy endometrium was observed at the second look hysteroscopy, in all the three patients. All 3 patients conceived after the procedure. Pregnancy was achieved after one IVF cycle with the transfer of one frozen embryo in case 1 and spontaneously in cases 2 and 3. Patient 1 was delivered by elective caesarean section due to placenta previa, while the other two patients had normal vaginal deliveries. Patient 1 had Retained Products of Conception requiring hysteroscopic removal using a 27 Fr Resectoscope. When using innovative miniaturized instruments and adequate surgical technique, hysteroscopic lysis of adhesions is a feasible and effective in-office strategy to restore fertility in patients with severe Asherman's syndrome. The use of 2D and 3D ultrasound played an important role in the preoperative workup of the patient with Asherman's syndrome.