In-Vitro Decidualization With Different Progesterone Concentration: Development of a Hormone-Responsive 3D Endometrial Tissue Using Rat Endometrial Tissues

Infertility in women is associated with various uterine and ovarian disorders. Treatment strategies for infertility can range from medications to embryo implantation through assisted reproductive technology (ART). ART has enabled considerable progress; however, there is currently no treatment to replace the endometrium itself. Decidualization requires a complex interaction between endometrial tissue and estrogen and progesterone. We aimed to create a three-dimensional endometrial-like tissue model using in-vitro cell sheet engineering with rat endometrium, and culture cells at different progesterone concentrations to mimic local concentrations. Histological and morphological changes revealed that development of the endometrial-like tissue was not proportional to progesterone concentrations in terms of thickness, number of endometrial glands, or area fraction of intimal glands. These results suggest that decidualization may not be commensurate with the local endometrial progesterone concentration. Notably, the number of endometrial glands increased in the high concentration group and compaction occurred, indicating that the endometrial conditions in the high concentration group may be most conducive to increase pregnancy rates. These findings suggest that there may be an "optimal progesterone concentration" for decidualization, application of which may lead to new strategies for improving pregnancy rates in women with infertility.

Effect of stem cell conditional medium-loading adhesive hydrogel on TGF-β1-induced endometrial stromal cell fibrosis

Introduction: Uterine adhesion (IUA) is a severe complication that results from uterine operations or uterine infections. Hysteroscopy is considered the gold standard for the diagnosis and treatment of uterine adhesions. Yet, this invasive procedure leads to re-adhesions after hysteroscopic treatment. Hydrogels loading functional additives (e.g., placental mesenchymal stem cells (PC-MSCs)) that can act as physical barriers and promote endometrium regeneration are a good solution. However, traditional hydrogels lack tissue adhesion which makes them unstable under a rapid turnover of the uterus, and PC-MSCs have biosafety risks when used as functional additives. Methods: In this study, we coupled an adhesive hydrogel with a PC-MSCs conditioned medium (CM) to form a hybrid of gel and functional additives (CM/Gel-MA). Results and Discussion: Our experiments show that CM/Gel-MA enhances the activity of endometrial stromal cells (ESCs), promotes cell proliferation, and reduces the expression of α-SMA, collagen I, CTGF, E-cadherin, and IL-6, which helps to reduce the inflammatory response and inhibit fibrosis. We conclude that CM/Gel-MA can more potentially prevent IUA by combining the physical barriers from adhesive hydrogel and functional promotion from CM.

MIR503HG silencing promotes endometrial stromal cell progression and metastasis and suppresses apoptosis in adenomyosis by activating the Wnt/β‑catenin pathway via targeting miR‑191

MIR503HG is a 786 bp long lncRNA located on chromosome Xq26.3, and it can regulate diverse cellular processes. The pathogenesis of adenomyosis (AD) is associated with endometrial stromal cells (ESCs). The present study investigated the specific role of MIR503HG in AD pathogenesis and progression using ESCs derived from the endometrium of patients with AD as a model. Expression of MIR503HG and microRNA (miR)-191 were assessed using reverse transcription-quantitative PCR. An immunocytochemistry assay was used to detect cytokeratin- or vimentin-positive ESCs. Transfections of ESCs with MIR503HG overexpression plasmid, short hairpin-MIR503HG and miR-191 inhibitor were performed. ESC viability, migration, invasion and apoptosis were evaluated using Cell Counting Kit-8, Transwell and flow cytometry assays. The association between MIR503HG and miR-191 was predicted by StarBase and confirmed using a dual-luciferase reporter assay. Expression of epithelial-mesenchymal transition-related markers (E-cadherin and N-cadherin) and Wnt/β-catenin pathway-related molecules (β-catenin) in ESCs were analyzed by western blotting. The isolated ESCs were vimentin-positive and cytokeratin-negative. MIR503HG was lowly expressed in the endometrial tissues derived from patients with AD. MIR503HG overexpression hindered ESC viability, migration and invasion while enhancing the apoptosis and downregulating miR-191 expression. MIR503HG knockdown induced the opposite effects, accompanied by downregulation of the E-cadherin expression and upregulation of N-cadherin and β-catenin levels. MIR503HG directly targeted miR-191 that was highly expressed in endometrial tissues derived from patients with AD. In ESCs, downregulation of miR-191 inhibited the viability, migration and invasion and the expression of N-cadherin and β-catenin levels while enhancing the apoptosis and E-cadherin expression in ESCs. Moreover, downregulation of miR-191 partially reversed the effect of MIR503HG knockdown. Collectively, overexpressed MIR503HG impeded the proliferation and migration of ESCs derived from endometrium of patients with AD, while promoting apoptosis via inhibition of the Wnt/β-catenin pathway via targeting miR-191.

Transposable Elements Continuously Remodel the Regulatory Landscape, Transcriptome, and Function of Decidual Stromal Cells

Gene expression evolution underlies the origin, divergence, and conservation of biological characters including cell-types, tissues, and organ systems. Previously we showed that large-scale gene expression changes in decidual stromal cells (DSCs) contributed to the origins of pregnancy in eutherians and the divergence of pregnancy traits in primates and that transposable elements likely contributed to these gene expression changes. Here we show that two large waves of TEs remodeled the transcriptome and regulatory landscape of DSCs, including a major wave in primates. Genes nearby TE-derived regulatory elements are among the most progesterone responsive in the genome and play essential roles in orchestrating progesterone responsiveness and the core function of decidual cells by donating progesterone receptor binding sites to the genome. We tested the regulatory abilities of 89 TE consensus sequences and found that nearly all of them acted as repressors in mammalian cells, but treatment with a histone deacetylase inhibitor unmasked latent enhancer functions. These data indicate that TEs have played an important role in the development, evolution, and function of primate DSCs and suggest a two-step model in which latent enhancer functions of TEs are unmasked after they lose primary repressor functions.

Transcriptional coactivator PGC-1α contributes to decidualization by forming a histone-modifying complex with C/EBPβ and p300

We previously reported that CCAAT/enhancer-binding protein beta (C/EBPβ) is the pioneer factor inducing transcription enhancer mark H3K27 acetylation (H3K27ac) in the promoter and enhancer regions of genes encoding insulin-like growth factor–binding protein-1 (IGFBP-1) and prolactin (PRL) and that this contributes to decidualization of human endometrial stromal cells (ESCs). Peroxisome proliferator–activated receptor gamma coactivator 1-alpha (PGC-1α; PPARGC1A) is a transcriptional coactivator known to regulate H3K27ac. However, although PGC-1α is expressed in ESCs, the potential role of PGC-1α in mediating decidualization is unclear. Here, we investigated the involvement of PGC-1α in the regulation of decidualization. We incubated ESCs with cAMP to induce decidualization and knocked down PPARGC1A to inhibit cAMP-induced expression of IGFBP-1 and PRL. We found cAMP increased the recruitment of PGC-1α and p300 to C/EBPβ-binding sites in the promoter and enhancer regions of IGFBP-1 and PRL, corresponding with increases in H3K27ac. Moreover, PGC-1α knockdown inhibited these increases, suggesting PGC-1α forms a histone-modifying complex with C/EBPβ and p300 at these regions. To further investigate the regulation of PGC-1α, we focused on C/EBPβ upstream of PGC-1α. We found cAMP increased C/EBPβ recruitment to the novel enhancer regions of PPARGC1A. Deletion of these enhancers decreased PGC-1α expression, indicating that C/EBPβ upregulates PGC-1α expression by binding to novel enhancer regions. In conclusion, PGC-1α is upregulated by C/EBPβ recruitment to novel enhancers and contributes to decidualization by forming a histone-modifying complex with C/EBPβ and p300, thereby inducing epigenomic changes in the promoters and enhancers of IGFBP-1 and PRL.

HOXA10 Regulates the Synthesis of Cholesterol in Endometrial Stromal Cells

BACKGROUND

The expression of homeobox A10 (HOXA10) in endometrial stromal cells is regulated by steroid hormones, especially by estrogen. As a precursor molecule of estrogen, abnormal cholesterol metabolism is significantly positively correlated with endometriosis. The purpose of this study was to explore the regulation of HOXA10 on cholesterol synthesis in endometrial stromal cells.

METHOD

mRNA expression data of eutopic endometrial stromal cell (ESC) and ovarian endometriotic cysts stromal cell (OESC) were download from the Gene Expression Omnibus (GEO) databases. Overexpression and silence of HOXA10 were conducted in cultured ESC and subjected to mRNA sequencing. The differentially expressed genes (DEGs) were selected by analyzing the sequencing data. Weighted gene co-expression network analysis (WGCNA) was applied to identify the key genes associated with HOXA10. The methylation rate of HOXA10 CpGs and the correlation between HOXA10 expression and the methylation in eutopic endometrial tissue (EU) and ovarian cyst (OC) were analyzed.

RESULTS

HOXA10 in ESC was significantly higher expressed than that in OESC. Six key genes (HMGCR, MSMO1, ACAT2, HMGCS1, EBP, and SQLE), which were regulated by HOXA10, were identified from the salmon4 module by WGCNA. All these key genes were enriched in cholesterol synthesis. Moreover, the expression of HOXA10 was negatively related to its CpGs methylation rate.

CONCLUSION

In this study, six key genes that were regulated by HOXA10 were selected, and all of them were enriched in cholesterol synthesis. This finding provided a new insight into the metabolic mechanism of cholesterol in ESC. It also provided a potential treatment strategy for cholesterol metabolism maladjustment in patients with ovarian endometriosis.

PGE2 and Thrombin Induce Myofibroblast Transdifferentiation via Activin A and CTGF in Endometrial Stromal Cells

Endometriosis is characterized by inflammation and fibrotic changes. Our previous study using a mouse model showed that proinflammatory factors present in peritoneal hemorrhage exacerbated inflammation in endometriosis-like grafts, at least in part through the activation of prostaglandin (PG) E2 receptor and protease-activated receptor (PAR). In addition, menstruation-related factors, PGE2 and thrombin (P/T), a PAR1 agonist induced epithelial-mesenchymal transition (EMT) of endometrial cells under hypoxia. However, the molecular mechanisms by which P/T induce development of endometriosis have not been fully characterized. To investigate the effects of P/T, RNA extracted from endometrial stromal cells (ESCs) treated with P/T were subjected to RNA sequence analysis, and identified activin A, FOS, and GATA2 as upregulated genes. Activin A increased the expression of connective tissue growth factor (CTGF) and mesenchymal marker genes in ESCs. CTGF induced the expression of fibrosis marker type I collagen, fibronectin, and α-smooth muscle actin (αSMA), indicating fibroblast to myofibroblast transdifferentiation (FMT) of ESCs. In addition, activin A, FOS, GATA2, CTGF, and αSMA were localized in endometriosis lesions. Taken together, our data show that P/T induces changes resembling EMT and FMT in ectopic ESCs derived from retrograde menstruation, and that these are associated with fibrotic changes in the lesions. Pharmacological means that block P/T-induced activin A and CTGF signaling may be strategies to inhibit fibrosis in endometriotic lesions.

The essential glucose transporter GLUT1 is epigenetically upregulated by C/EBPβ and WT1 during decidualization of the endometrium

Human endometrial stromal cells (ESCs) differentiate into decidual cells by the action of progesterone, which is essential for implantation and maintenance of pregnancy. We previously reported that glucose uptake by human ESCs increases during decidualization and that glucose is indispensable for decidualization. Although glucose transporter 1 (GLUT1) is upregulated during decidualization, it remains unclear whether it is involved in glucose uptake. Here, we attempted to determine the role of GLUT1 during decidualization as well as the factors underlying its upregulation. ESCs were incubated with cAMP to induce decidualization. Knockdown of GLUT1 suppressed cAMP-increased glucose uptake and the expressions of specific markers of decidualization, IGF-binding protein-1 (IGFBP-1), and prolactin (PRL). To investigate the regulation of GLUT1 expression, we focused on CCAAT enhancer-binding protein β (C/EBPβ) and Wilms' tumor 1 (WT1) as the upstream transcription factors regulating GLUT1 expression. Knockdown of either C/EBPβ or WT1 suppressed cAMP-increased GLUT1 expression and glucose uptake. cAMP treatment also increased the recruitment of C/EBPβ and WT1 to the GLUT1 promoter region. Interestingly, cAMP increased the H3K27 acetylation (H3K27ac) and p300 recruitment in the GLUT1 promoter region. Knockdown of C/EBPβ or WT1 inhibited these events, indicating that both C/EBPβ and WT1 contribute to the increase of H3K27ac by recruiting p300 to the GLUT1 promoter region during decidualization. These findings indicate that GLUT1 is involved in glucose uptake in ESCs during decidualization, thus facilitating the establishment of pregnancy.

MiR-543 Inhibits the Migration and Epithelial-To-Mesenchymal Transition of TGF-β-Treated Endometrial Stromal Cells via the MAPK and Wnt/β-Catenin Signaling Pathways

Intrauterine adhesion (IUA) is one of the most prevalent reproductive system diseases in females. MicroRNAs (miRNAs) are reported to be master regulators in a variety of diseases, including IUA, but the role of microRNA-543 (miR-543) in IUA remains to be elucidated. In this study, we observed that miR-543 was downregulated in transforming growth factor-beta (TGF-β)-treated endometrial stromal cells (ESCs). Functionally, we observed that miR-543 suppressed the migration, epithelial-to-mesenchymal transition (EMT), and inhibited expression of extracellular matrix (ECM) proteins in TGF-β-treated ESCs. Mechanistically, MAPK1 is targeted by miR-543 after prediction and screening. A luciferase reporter assay demonstrated that miR-543 complementarily binds with the 3' untranslated region of mitogen-activated protein kinase 1 (MAPK1), and western blot analysis indicated that miR-543 negatively regulates MAPK1 protein levels. In addition, results from rescue assays showed that miR-543 inhibits the migration and EMT of TGF-β-treated ESCs by targeting MAPK1. In addition, we observed that miR-543 inactivates the Wnt/β-catenin signaling pathway through inhibiting the phosphorylation of MAPK1 and β-catenin. Finally, we confirmed that miR-543 represses migration, EMT and inhibits levels of ECM proteins in TGF-β-treated ESCs by targeting the Wnt/β-catenin signaling pathway. Our results demonstrated that miR-543 suppresses migration and EMT of TGF-β-treated ESCs by targeting the MAPK and Wnt/β-catenin pathways.

Identification of HOXA10 target genes in human endometrial stromal cells by RNA-seq analysis

Homeobox A10 (HOXA10) is a transcription factor belonging to the homeobox gene family. It is highly expressed in endometrial stromal cells (ESCs) and plays essential roles in the proliferation and differentiation of endometrium, the establishment of endometrial receptivity and embryo implantation. However, little is known about the target genes and signaling pathways regulated by HOXA10 in ESCs. In this study, we identified 1830 transcripts regulated by HOXA10 in ESCs by RNA interference (RNAi) and RNA-sequencing (RNA-seq) analysis, of which 980 were positively regulated by HOXA10 and 850 were negatively regulated by HOXA10. Interestingly, matrix metallopeptidase-11 was downregulated by HOXA10 in stromal cells verified by quantitative real-time polymerase chain reaction and western blot analysis. Pathway analysis demonstrated that the target genes were enriched in various pathways, including cellular metabolism, DNA replication and repair, cell junction, and lysosome and signal transduction. The results of the present study provide novel insights into the mechanism underlying HOXA10 regulation in ESCs and may identify novel targets for the diagnosis and treatment of endometrium-related infertility.

The expression of hepatoma upregulated protein in human endometrium during the menstrual cycle

AIMS

Human endometrium resists embryo implantation except during the window period. Currently, uterine HURP expression is known to be involved in endometrial stromal proliferation during embryo implantation of mice. Thus, we demonstrated hepatoma up-regulated protein (HURP) expression in the human endometrium during the menstrual cycle, as well as HURP regulation in endometrial stromal cells (ESCs).

MATERIALS AND METHODS

We collected human endometrial samples from different menstrual cycle phases (early/late proliferative, and early/mid/late secretory), and then analyzed these samples by immunohistochemistry, reverse transcription-polymerase chain reaction, and Western blotting. We also assessed the effects of two sex-steroid hormones, 17β-estradiol (E2) and 4-pregnene-3,20-dione (P4) on the cultured stromal cells.

RESULTS

HURP protein was localized to the nucleus of the endometrial both epithelial and stromal cells in all stages. Also, HURP mRNA and protein in human endometrial tissue was significantly up-regulated during late-proliferative and secretory phase, compared with early-proliferative phase. In ESCs, HURP expression was regulated by E2, but not P4.

CONCLUSIONS

We indicated that cyclic changes in HURP expression in human normal ESC strongly suggested up-regulation by estrogen. Taken together, since estrogen responses are fundamental in endometrial biology, uterine expression of HURP may be involved in female reproductive function during the menstrual cycle.

Cigarette Smoke Extract Activates Hypoxia-Inducible Factors in a Reactive Oxygen Species-Dependent Manner in Stroma Cells from Human Endometrium

Cigarette smoking (CS) is a major contributing factor in the development of a large number of fatal and debilitating disorders, including degenerative diseases and cancers. Smoking and passive smoking also affect the establishment and maintenance of pregnancy. However, to the best of our knowledge, the effects of smoking on the human endometrium remain poorly understood. In this study, we investigated the regulatory mechanism underlying CS-induced hypoxia-inducible factor (HIF)-1α activation using primary human endometrial stromal cells and an immortalized cell line (KC02-44D). We found that the CS extract (CSE) increased reactive oxygen species levels and stimulated HIF-1α protein stabilization in endometrial stromal cells, and that CS-induced HIF-1α-dependent gene expression under non-hypoxic conditions in a concentration- and time-dependent manner. Additionally, we revealed the upregulated expression of a hypoxia-induced gene set following the CSE treatment, even under normoxic conditions. These results indicated that HIF-1α might play an important role in CS-exposure-induced cellular stress, inflammation, and endometrial remodeling.

Mitochondrial and Metabolic Dynamics of Endometrial Stromal Cells During the Endometrial Cycle

The endometrial cycle in response to hormonal stimulation is essential for implantation. The female has endometrium that repeats this cycle through about half of a lifetime. The cycle includes three phases, proliferative, secretory, and menstrual, and each phase has distinct characteristics. The endometrial stromal cells (EnSCs) in each phase also have specialized characteristics, including cell cycle, morphologies, and cellular metabolic state. So we hypothesized that the cells in each phase have unique mitochondrial morphologies because they are generally linked to cellular metabolic state. To investigate the metabolic characteristics in each phase, we investigated the mitochondrial morphologies by transmission electron microscopy, oxygen consumption rate (OCR), and intracellular adenosine triphosphate (ATP) production. The decidualized EnSCs have shorter mitochondria than those in the proliferative phase. Besides, they also displayed distinct intracellular structural characteristics compared with the proliferative phase, such as ribosome-rich endoplasmic reticulum and increased formation of vesicles. OCR and luminescent ATP detection assay revealed that the basal respiration and ATP production in the decidualized EnSCs were lower than those in the proliferative phase. Thus, we concluded that morphological and intracellular structural changes were induced during the decidualization. Moreover, the decreased mitochondrial length was shown to correlate with decreased dependency on oxidative phosphorylation and ATP concentration in EnSCs.

ALK3-SMAD1/5 Signaling Mediates the BMP2-Induced Decrease in PGE2 Production in Human Endometrial Stromal Cells and Decidual Stromal Cells

BMP2 is a critical factor that is involved in the processes of embryo implantation and uterine decidualization. The expression of cyclooxygenase (COX) and subsequent prostaglandin E2 (PGE2) production are critical for successful pregnancy. However, it is not clear whether BMP2 can regulate the production of PG during endometrial decidualization. The aim of this study was to investigate the effects of BMP2 on COX-1 expression and PGE2 production as well as the underlying molecular mechanisms in the human endometrium. Immortalized human endometrial stromal cells (HESCs) and human decidual stromal cells (HDSCs) were used as the study model to investigate the effects of BMP2-induced cellular activities. Our results showed that BMP2 treatment significantly decreased PGE2 production by downregulating COX-1 expression in both human endometrial stromal and decidual stromal cells. Additionally, BMP2 induced an increase in the levels of phosphorylated SMAD1/5/8, and this effect was completely abolished by the addition of the inhibitors DMH-1 and dorsomorphin, but not by SB431542. Knocking down ALK3 completely reversed the BMP2-induced downregulation of COX-1. Moreover, concomitantly knocking down SMAD1 and SMAD5 completely reversed the BMP2-induced downregulation of COX-1. Our results indicated that BMP2 decreased PGE2 production by downregulating COX-1 expression, most likely through the ALK3/SMAD1-SMAD5 signaling pathway in human endometrial stromal and human decidual stromal cells. These findings deepen our understanding of the functional role of BMP2 in the regulation of endometrial decidualization in humans.

Localization of integrin heterodimer α9β1 on the surface of uterine endometrial stromal and epithelial cells in mice

Previously, we reported that endometrial stromal (ES) and endometrial epithelial (EE) cells did not attach to tenascin C, indicating the absence of active integrin α₉β₁ on the surface of mouse ES and EE cells. However, that study used recombinant tenascin C without fibronectin (FN) type III repeats interacting with integrin heterodimers. Therefore, we re-evaluated the presence of integrin α₉β₁ actively functioning on the surface of mouse ES and EE cells using full-length native tenascin C with FN type III repeats. The functionality of integrin α₉β₁ was confirmed using attachment and antibody inhibition assays. Both mouse ES and EE cells showed significantly increased adhesion to native tenascin C, and functional blocking of integrin α₉β₁ significantly inhibited adhesion to native tenascin C. These results demonstrate that the integrin α₉ and β₁ subunits function as active heterodimers on the plasma membrane of mouse ES and EE cells, respectively.

Activation of the Hippo/TAZ pathway is required for menstrual stem cells to suppress myofibroblast and inhibit transforming growth factor β signaling in human endometrial stromal cells

STUDY QUESTION

Can menstrual stem cells (MenSCs) inhibit myofibroblast differentiation and reverse transforming growth factor β (TGFβ)-mediated activation of myofibroblast phenotypes in human endometrial stromal cells (ESCs)?

SUMMARY ANSWER

MenSCs suppressed endometrial myofibroblast differentiation and reversed TGFβ-mediated activation of myofibroblast phenotypes, which might be associated with activation of the Hippo/TAZ pathway.

WHAT IS KNOWN ALREADY

The potential effect of MenSCs as a cell therapy include attenuation of intrauterine adhesions, but the underlying mechanisms by which MenSCs exerts these effects are not entirely understood.

STUDY DESIGN, SIZE, DURATION

We evaluated the antagonistic effects of MenSCs on myofibroblast differentiation as well as the broader effect of the Hippo/TAZ signaling pathway on TGFβ-mediated induction of myofibroblast gene expression. The study design was based on a cohort of clinical proliferative phase endometrial samples obtained from three healthy premenopausal females with regular menstrual cycles.

PARTICIPANTS/MATERIALS, SETTING, METHODS

ESCs were cocultured with MenSCs or in MenSC-conditioned medium. Fibrotic markers (αSMA, collagen I, CTGF and fibronectin) as well as proliferation and wound-healing abilities were evaluated. Components of the Hippo/TAZ pathway (TAZ, p-TAZ, MOB1, p-MOB1, LATS1 and p-LATS1) were also investigated. Cell Counting Kit 8, wound healing assay, real-time PCR, western blotting, immunofluorescence and shRNA knockdown approaches were used to validate the findings.

MAIN RESULTS AND THE ROLE OF CHANCE

MenSCs inhibited myofibroblast activation, resulting in more rapid proliferation of ESCs. MenSCs downregulated the expression of myofibroblast markers αSMA and collagen I and promoted endometrial wound healing. Coculture with MenSCs also attenuated the TGFβ-mediated increase in expression of fibrotic marker genes αSMA, collagen I, CTGF and fibronectin, and restored the wound-healing ability inhibited by TGFβ. MenSCs induced Hippo/TAZ pathway activation, resulting in nuclear export and cytoplasmic retention of TAZ. TAZ inhibition was demonstrated to have similar effects even in the absence of MenSCs, and inhibition of TAZ was sufficient to attenuate TGFβ-mediated myofibroblast activation.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This study included only in vitro experiments. Thus, additional data from in vivo experiments are needed in a future study.

WIDER IMPLICATIONS OF THE FINDINGS

The Hippo/TAZ pathway may be an important therapeutic target for endometrial fibrosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Natural Science Foundation of China (No. 81601236) and Zhejiang Provincial Natural Science Foundation of China (LY19H040009). None of the authors has any competing interests to declare.

Comparative secretome profile analysis of cultured immortalized human endometrial stromal cells supplemented with implanted versus nonimplanted blastocyst-conditioned medium: A preliminary analysis

AIM

Human endometrial stromal cells (HESCs) were previously shown to be capable of discriminating embryos with different qualities. Here we aimed to compare the specific response of the HESC secretome to implanted blastocyst-conditioned medium (BCM) versus nonimplanted medium and identify cytokine candidates useful for the assessment of blastocyst implantation.

METHODS

Cleavage embryos were individually cultured in one microdrop of medium for blastocyst formation. The BCM was collected after fresh blastocyst transfer on day 5 and used to supplement HESC culture medium. A high-throughput antibody array covering 440 cytokines was used to detect the secretory proteins of HESCs supplemented with implanted or nonimplanted BCM.

RESULTS

A total of 22 differentially expressed proteins were found out of 440 cytokines in the supernatant of HESCs supplemented with BCM from the implanted group compared to the nonimplanted group, including seven upregulated and 15 downregulated proteins. Gene Ontology enrichment analysis showed that the differentially expressed proteins were mainly involved in cell chemotaxis and motility, and ERK1/2 cascade regulation. Kyoto Encyclopedia of Genes and Genomes analysis suggested that the mitogen-activated protein kinase and phosphatidylinositol 3 kinase/Akt pathways were mainly involved.

CONCLUSION

HESCs specifically responded to BCM from different quality blastocysts, a finding that can be used to develop a novel approach for blastocyst quality assessment.

In-vitro models of human endometriosis

Endometriosis is one of the most common benign gynecological diseases in women of reproductive age worldwide. In past decades, a number of in-vitro models have been used to investigate the pathology and therapeutic methods for the treatment of endometriosis. The current review summarized the majority of currently available in-vitro models, which utilize a variety of cell or tissues types, including endometriotic cell lines, primary endometrial stromal cells, endometrial stem cells, endometrial explants, peritoneal explants and immune cells. These cells or tissues are cultured individually, co-cultured in 2D or 3D systems with various matrices or cultured in chicken chorioallantotic membranes and amniotic membranes culture systems. These models are able to represent one or more aspects of the process of endometriosis. These models are helpful and can be used to investigate the development of endometriosis and the underlying mechanisms of this disorder in detail, and help investigators select appropriate models for their experiments. Recently, the new concept of endometriosis as a fibrotic condition will lead research to investigate the differentiation of myofibroblasts and the development of fibrosis in endometriotic lesions, which will increase the development of novel models that can be used to investigate endometriotic fibrosis.

SCM-198 protects endometrial stromal cells from oxidative damage through Bax/Bcl-2 and ERK signaling pathways

Increasing amounts of evidence demonstrated that accumulative reactive oxygen species (ROS) and apoptosis of human endometrial stromal cells (ESCs) are closely associated with endometrial dysfunction induced by oxidative stress, which plays an important role in the pathological process of multiple gynecological and reproduction-related diseases. SCM-198, an alkaloid active component of Leonurus japonicas Houtt, has been reported to have anti-oxidative activity. However, the specific mechanisms of SCM-198 in the prevention of endometrial damage remain unknown. In the present study, we assessed the effect of SCM-198 on hydrogen peroxide (H2O2)-induced oxidative injury in ESCs. ESCs were pretreated with SCM-198 for 4 h and then challenged with H2O2. Morphology changes, apoptosis rate, and intracellular ROS production were measured to assess the level of oxidative injury. Flow cytometry and western blot analysis were performed to detect the expression levels of Bax, Bcl-2, active-caspase-3, and mitogen-activated protein kinases pathways. Classic inflammation cytokines were measured by real-time polymerase chain reactions. Our results showed that SCM-198 attenuated apoptosis and ROS generation of ESCs induced by H2O2. H2O2 induced the apparent apoptotic characteristics, including fragmentation of DNA, upregulation of Bax/Bcl2, activation of caspase-3, and secretion of inflammation cytokines, which were all ameliorated by SCM-198. Furthermore, H2O2-induced apoptosis-related ERK1/2 pathway activation was restrained by SCM-198 pretreatment. These findings suggested that SCM-198 could protect ESCs from oxidative injury, mainly by inhibiting oxidative stress and reducing apoptosis.

Endoplasmic reticulum stress is involved in lipopolysaccharide-induced inflammatory response and apoptosis in goat endometrial stromal cells

Endoplasmic reticulum (ER) stress is involved in regulating cell metabolism, apoptosis, autophagy, and survival. However, there is not enough information about the role of ER stress in lipopolysaccharide (LPS)-induced apoptosis and inflammatory cytokine secretion in the uterus. In this study, we found that LPS induced apoptosis and inflammation in goat endometrial stromal cells (ESCs). LPS treatment inhibited cell viability and cell proliferation. In addition, the genes associated with proliferation, such as proliferating cell nuclear antigen and MKI67, were affected by LPS treatment. Moreover, LPS increased the secretion of interleukin (IL)-1β and IL-8, promoting the levels of MYD88, caspase1, and TRL4. The 4-phenylbutyric acid pretreatment inhibited the expression of unfolded protein response proteins and the secretion of inflammatory cytokines in LPS-treated cells. However, blockage of inositol-requiring enzyme 1 and activating transcription factor 6 did not significantly reduce apoptosis and inflammatory cytokine secretion. Collectively, ER stress involved in LPS-induced apoptosis and inflammatory cytokine increased in goat ESCs. This study provides new insight into the function of ER stress in the pathological process.

Effect of mistletoe on endometrial stromal cell survival and vascular endothelial growth factor expression in patients with endometriosis

Research Question: To evaluate the effect of mistletoe on the cell viability of patients with endometriosis, the expression levels of vascular endothelial growth factor (VEGF) were measured, and the change in the expression level of VEGF following mistletoe treatment was recorded. Design: Forty reproductive-aged women with endometriosis (stage I/II [group 1, n=20], and stage III/IV [group 2, n=20]) were prospectively enrolled. Twenty women who underwent gynaecologic operations for benign conditions were selected as the control group. Both eutopic and ectopic endometrial tissues were obtained from the endometriosis patients. The endometrial tissues were cultured and the stromal cells were separated. The cells were cultured for 24 hours with peritoneal fluid from patients and controls with and without mistletoe supplementation (200 ng/mL), respectively. The MTT assay was used to assess cell viability, and VEGF expression was analysed by Western blotting and ELISA. Results: Using peritoneal fluid from endometriosis patients treated with mistletoe, we found that both eutopic and ectopic endometrial stromal cell viability increased after treatment with peritoneal fluid from patients with early-stage (I and II) endometriosis. After mistletoe treatment, the cell viability was decreased, in both eutopic and ectopic endometrial stromal cells in all stages of endometriosis. These findings were verified consistently by evaluating the expression and concentration of VEGF, a marker of angiogenesis. Conclusions: The present study showed that mistletoe can reduce the cell viability of endometrial stromal cells and the peritoneal fluid-induced elevation of VEGF in eutopic and ectopic endometrial stromal cells obtained from endometriosis patients, especially in the early stage. Mistletoe might have anti-angiogenic activity on endometrial stromal cells and thus is a potential candidate for the treatment of endometriosis.

Effect of S100A6 over-expression on β-catenin in endometriosis

AIM

S100A6 is over-expressed in several human tumors, including pancreatic carcinoma, malignant fibrous histiocytoma, breast, colon, and gastric carcinoma, but little is known about the role of S100A6 in endometriosis. The aim of the present study was to investigate the effect of S100A6 over-expression on β-catenin in endometrial stromal cells.

METHODS

Endometrial stromal cells were transfected with an hS100A6-expressing recombinant lentivirus construct. The expression of β-catenin was assessed using western blot and reverse transcription-polymerase chain reaction.

RESULTS

S100A6 over-expression promoted β-catenin expression at the RNA and protein levels, in endometrial stromal cells.

CONCLUSIONS

S100A6 induces expression of β-catenin in endometrial stromal cells.

Estrogen promotes the survival of human secretory phase endometrial stromal cells via CXCL12/CXCR4 up-regulation-mediated autophagy inhibition

STUDY QUESTION

What mechanism is involved in regulating the autophagy of endometrial stromal cells (ESCs), and does it participate in the pathogenesis of endometriosis?

SUMMARY ANSWER

CXCL12 down-regulates secretory phase ESC autophagy.

WHAT IS KNOWN ALREADY

mTOR (mammalian target of rapamycin), the major negative regulator of autophagy, is abnormally increased in endometriotic lesions and is involved in the direct regulation of endometrial stromal cell (ESC) apoptosis.

STUDY DESIGN, SIZE, DURATION

Autophagy was measured by transmission electron microscopy and immunofluorescence, and in vitro analysis was used to measure estrogen/CXCL12/CXCR4 signaling-mediated ESC autophagy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 31 controls and 31 women with histologically confirmed endometriosis were included. We measured the autophagy level of normal and endometriosis-derived endometrium, and its relationship to the stage of endometriosis, as well as the potential molecular and signaling pathways that mediate the aberrant autophagy in endometriosis.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared with control secretory phase ESCs, a significant reduction of the autophagy grade (as observed in TEM), punctuate LC3B staining (as observed in immunofluorescence assays), and autophagy-associated protein levels were exhibited in secretory phase eutopic ESCs (P < 0.05) and ectopic ESCs (P < 0.05) from women with endometriosis. In addition, the autophagy level was strongly negatively correlated with the CXCL12 concentration in ESCs (R(2) = -0.9694). However, there was no significant difference in autophagy grade or CXCL12 concentration between stage I-II and stage III-IV endometriosis-derived ectopic ESCs (P > 0.05). Based on a human autophagy PCR array, CXCL12 and CXCR4, which is the CXCL12 receptor, in ESCs were predicted to be molecules that mediate the abnormally lower autophagy in endometriosis. Accordingly, after estradiol (E2) treatment a marked increase in CXCL12 secretion (1.71-fold, P < 0.01) and CXCR4 expression (5.07-fold, P < 0.01) in secretory phase ESCs was observed together with decreases in autophagy grade (TEM), punctuate LC3B immunofluorescent staining and autophagy-associated protein levels (P < 0.05). These changes could be reversed by progesterone (P4) (P < 0.05). The suppression of autophagy induced by E2 and recombinant human CXCL12 protein could be abrogated by an anti-CXCR4 neutralizing antibody and by a NF-κB inhibitor (P < 0.05), respectively. In addition, estrogen-stimulated CXCL12 secretion led to a low population of S phase cells (P < 0.05), as well as a low level of apoptosis (P < 0.05) in secretory phase ESCs.

LIMITATIONS, REASONS FOR CAUTION

Further studies are needed to examine the mechanism of autophagy on ESC apoptosis.

WIDER IMPLICATIONS OF THE FINDINGS

Measures to increase in endometrial autophagy might be a valid, novel approach to reduce local E2-dependent growth of endometriotic tissue.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the National Natural Science Foundation of China (NSFC) (81471513, 81471548 and 81270677), the Training Program for Young Talents of Shanghai Health System XYQ2013104, the Program for Zhuoxue of Fudan University, and the Program for Creative Talents Education of Key Disciplines of Fudan University. None of the authors has any conflict of interest to declare.

Indoleamine 2,3-dioxygenase-1 (IDO1) in human endometrial stromal cells induces macrophage tolerance through interleukin-33 in the progression of endometriosis

In the peritoneal fluid, macrophages and their secretory cytokines are essential for endometriosis, but the factors that favor their involvement in the endometriosis-associated inflammatory response are still elusive. Given the anomalous expression of indoleamine 2,3-dioxygenase-1 (IDO1) in endometrial stromal cells (ESCs) and its potentially important roles in immune modulation, we aimed to determine the effects of IDO1 in ESCs on macrophages and the mechanism of those effects. Normal ESCs and ectopic ESCs transfected with the SD11-IDO1 shRNA (short hairpin RNA) or vector-only plasmid SD11 were subsequently co-cultured with peripheral blood (PB)-derived monocytes (PBMC)-driven macrophages directly and indirectly. Cytokine production was determined by analyzing the supernatant of the co-culture unit by enzyme-linked immunosorbent assay (ELISA). The phenotypes and the phagocytic ability of the macrophages were determined by flow cytometry. Compared to normal ESCs, the PBMC-driven macrophages co-cultured with ectopic ESCs displayed lower phagocytic ability. Additionally, macrophages co-cultured with ectopic ESCs exhibited higher levels of CD163 and CD209 and lower levels of HLA-DR and CD11c. Moreover, both the intracellular expression and extracellular secretion of interleukin-10 (IL-10) and transforming growth factor-β1 (TGF-β1) were significantly increased, while that of IL-12p70 was decreased in macrophages after being co-cultured with ectopic ESCs. However, there was no significant difference in macrophage phagocytic ability, immunophenotype or cytokine secretion between the direct and indirect co-culture units. Reversely, SD11-IDO1 shRNA transfection of ectopic ESCs could abrogate the decreased phagocytic ability and alternative activation of macrophages in ectopic ESC-macrophage co-culture unit, suggesting that higher IDO1 in ectopic ESCs was indispensable for the induction of macrophage tolerance. Furthermore, the decrease in phagocytic macrophages and alternatively activated macrophages induced by IDO1 in ectopic ESCs was reversed by the addition of an IL-33 inhibitor, that is, soluble ST2 (sST2). Therefore, through the activation of IL-33, the increased expression of IDO1 in ectopic ESCs contributed to the truncated phagocytic ability of macrophages in endometriosis.

CAPN 7 promotes the migration and invasion of human endometrial stromal cell by regulating matrix metalloproteinase 2 activity

BACKGROUND

Matrix metalloproteinase 2 (MMP-2) has been reported to be an important regulator of cell migration and invasion through degradation of the extracellular matrix (ECM) in many diseases, such as cancer and endometriosis. Here, we found calcium-activated neutral protease 7 (CAPN 7) expression was markedly upregulated in the eutopic endometrium and endometrial stromal cells of women diagnosed with endometriosis. Our studies were carried out to detect the effects of CAPN 7 on human endometrial stromal cell (hESC) migration and invasion.

METHODS

Western blotting and quantitative real-time PCR were used to detect the expression of CAPN 7 in endometriosis patients and normal fertile women. Scratch-wound-healing and invasion chamber assay were used to investigate the role of CAPN 7 in hESC migration and invasion. Western blotting, quantitative real-time PCR and zymography were carried out to detect the effect of CAPN 7 on the expressions and activity of MMP-2.

RESULTS

CAPN 7 was markedly up-regulated in endometriosis, thereby promoting the migration and invasion of hESC. CAPN 7 overexpression led to increased expression of MMP-2 and tissue inhibitor of metalloproteinases 2 (TIMP-2); CAPN 7 knockdown reversed these changes. CAPN 7 increased MMP-2 activity by increasing the ratio of MMP-2 to TIMP-2. We also found that OA-Hy (an MMP-2 inhibitor) decreased the effects of CAPN 7 overexpression on hESC migration and invasion by approximately 50% and 55%, respectively. Additionally, a coimmunoprecipitation assay demonstrated that CAPN 7 interacted with activator protein 2α (AP-2α): an important transcription factor of MMP-2.

CONCLUSIONS

CAPN 7 promotes hESC migration and invasion by increasing the activity of MMP-2 via an increased ratio of MMP-2 to TIMP-2.