Glutaminolysis regulates endometrial fibrosis in intrauterine adhesion via modulating mitochondrial function

BACKGROUND

Endometrial fibrosis, a significant characteristic of intrauterine adhesion (IUA), is caused by the excessive differentiation and activation of endometrial stromal cells (ESCs). Glutaminolysis is the metabolic process of glutamine (Gln), which has been implicated in multiple types of organ fibrosis. So far, little is known about whether glutaminolysis plays a role in endometrial fibrosis.

METHODS

The activation model of ESCs was constructed by TGF-β1, followed by RNA-sequencing analysis. Changes in glutaminase1 (GLS1) expression at RNA and protein levels in activated ESCs were verified experimentally. Human IUA samples were collected to verify GLS1 expression in endometrial fibrosis. GLS1 inhibitor and glutamine deprivation were applied to ESCs models to investigate the biological functions and mechanisms of glutaminolysis in ESCs activation. The IUA mice model was established to explore the effect of glutaminolysis inhibition on endometrial fibrosis.

RESULTS

We found that GLS1 expression was significantly increased in activated ESCs models and fibrotic endometrium. Glutaminolysis inhibition by GLS1 inhibitor bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl) ethyl sulfide (BPTES or glutamine deprivation treatment suppressed the expression of two fibrotic markers, α-SMA and collagen I, as well as the mitochondrial function and mTORC1 signaling in ESCs. Furthermore, inhibition of the mTORC1 signaling pathway by rapamycin suppressed ESCs activation. In IUA mice models, BPTES treatment significantly ameliorated endometrial fibrosis and improved pregnancy outcomes.

CONCLUSION

Glutaminolysis and glutaminolysis-associated mTOR signaling play a role in the activation of ESCs and the pathogenesis of endometrial fibrosis through regulating mitochondrial function. Glutaminolysis inhibition suppresses the activation of ESCs, which might be a novel therapeutic strategy for IUA.

MiR-135a-5p regulates window of implantation by suppressing pinopodes development and decidualization of endometrial stromal cells

PURPOSE

The window of implantation (WOI) is a brief period during which the endometrium is receptive to embryo implantation. This study investigated the relationship between miR-135a-5p and endometrial receptivity.

METHODS

Peripheral blood was collected on the day of ovulation and the 5th day after ovulation for high-throughput sequencing from women who achieved clinical pregnancy through natural cycle frozen embryo transfer. RT-qPCR assessed miR-135a-5p expression in the endometrium tissue or cells during the mouse implantation window or decidualization. Scanning electron microscopy was utilized to observe pinopode morphology and quantity in mice overexpressing miR-135a-5p during the WOI. Human endometrial stromal cells (HESC) and artificial induction of mouse uterine decidualization were used to explore whether miR-135a-5p overexpression inhibits decidualization by regulating HOXA10 and BMPR2. Furthermore, the impact of miR-135a-5p on HESC proliferation and HTR8/SVneo invasion was explored.

RESULTS

A total of 54 women were enrolled in the study. bioinformatics analysis and animal models demonstrated that miR-135a-5p was significantly downregulated during the WOI, and its high expression can lead to abnormal pregnancy outcomes. Overexpression of miR-135a-5p resulted in the absence of pinopode in mouse endometrial tissue during the WOI. High miR-135a-5p levels were found to potentially inhibit endometrial tissue decidualization by downregulating HOXA10 and BMPR2 expression. Finally, CEBPD was identified as a potential regulator of miR-135a-5p, which would explain the decreased miR-135a-5p expression during the WOI.

CONCLUSION

MiR-135a-5p expression is significantly downregulated during the WOI. High miR-135a-5p levels suppress pinopode development and endometrial tissue decidualization through HOXA10 and BMPR2, contributing to inadequate endometrial receptivity.

A LIGHT-HVEM/LTβR axis contributes to the fibrosis of intrauterine adhesion

Intrauterine adhesion (IUA) is a fibrotic disease, with complex and multifactorial process, causing menstrual disorders, pregnancy loss or infertility. LIGHT (also named TNFSF14), mainly expressed by immune cells, has been reported to be associated with tissue fibrosis. However, the features of immunocyte subsets, the expression and roles of LIGHT and its receptor HVEM (herpes virus entry mediator) and LTβR (lymphotoxin beta receptor) in IUA remain largely unknown. Compared with the control group, we observed increased ratios of CD45⁺ cells, neutrophils, T cells, macrophages and decreased natural killer cells proportion, and high LIGHT expression on CD4⁺ T cells and macrophages in IUA endometrium. Further analysis showed there was a positive correlation between upregulated profibrotic factors (e.g., ɑ-smooth muscle actin, transforming growth factor β1) and HVEM in IUA endometrial tissue. More importantly, recombinant human LIGHT protein directly up-regulated the expression of HVEM, LTβR, profibrotic and proinflammatory factors expression in human endometrial stromal cells. These findings reveal abnormal changes of immune cell subsets proportion and the overexpression of LIGHT-HVEM/LTβR axis in IUA endometrium, should contribute to inflammation and fibrosis formation of IUA.

SKP2 regulates ZEB1 expression and stimulates eutopic endometrial stromal cell invasion and proliferation of adenomyosis

Though endometriosis is benign, however, it shares certain characteristics with cancers, such as the ability to invade and metastasize. Previous studies have demonstrated that S-phase kinase associated protein2 (SKP2) promotes invasion, tumorigenesis, and metastasis. However, its correlation with adenomyosis is unclear. Herein, we aimed to look into SKP2 expression patterns and regulatory effects on endometrial stromal cell (ESC) proliferation and invasion, and its internal mechanism in adenomyosis. Western blot, qRT-PCR, and immunochemistry were carried out for detecting SKP2 and ZEB1 expression in ESC of adenomyosis and adenomyosis endometrial tissue. The primary ESCs were identified using immunofluorescence. SKP2 knockdown was accomplished in vitro by transfecting a particular lentivirus vector. The colony formation and CCK-8 assays were carried out for assessing cell proliferation, while cell invasion potential was assessed using the transwell assay. Both SKP2 and ZEB1 were found to be significantly upregulated in adenomyosis endometrial tissue. Knockdown of SKP2 inhibited adenomyotic ESC invasion and proliferation. Further experiments showed that knocking out SKP2 reduced ZEB1 expression in adenomyotic ESCs. Our results showed that SKP2 could regulate ZEB1 expression, and increased SKP2 may play a role in the pathogenesis of adenomyosis and stimulating ESC proliferation and invasion.

Senolytic treatment modulates decidualization in human endometrial stromal cells

Decidualization - the differentiation of endometrial stromal cells (ESCs) into decidual cells - is a crucial step for successful embryo implantation and placentation that is initiated in the secretory phase of the menstrual cycle. During decidualization, ESCs undergo proliferation arrest and secrete inflammatory mediators, including senescence-associated secretory phenotype (SASP). Although several senolytic agents improve age-related diseases, their effects on cellular senescence in decidualizing ESCs has not been explored. To do this, we treated decidualized ESCs with the senolytic agents Quercetin (Que), Dasatinib (Das), and BPTES. Que decreased the number of senescence-associated β-galactosidase (SA-β-Gal) positive cells and expression of senescence markers in ESCs treated with the decidual stimulus (dibutyryl-cAMP plus progesterone: DP). Concomitantly, Que markedly increased the expression of the decidualization markers IGFBP1, PRL, and FOXO1, in decidualizing ESCs. Similar to Que, Das also stimulated decidualization. Treatment with a combination of Que and Das synergistically increased the expression of decidualization markers and senescence markers compared with treatment with Que or Das alone. However, BPTES did not enhance the expression of decidualization markers. These results imply that treatment with Que and/or Das can remove senescent decidual cells and enhance the decidualization of the rest of ESCs. Thus, senolytic modulation of abnormal ESC decidualization could alleviate infertility caused by dysfunctions of endometrial receptivity and embryo implantation.

Metformin attenuates expression of angiogenic and inflammatory genes in human endometriotic stromal cells

Endometriosis is a benign gynecological disease that is manifested by the presence and growth of endometrial cells and glands outside the uterine. Active angiogenesis, migration, and invasion of endometrial tissue outside the uterine are critical for the development of endometriosis and lead to the survival and growth of endometriotic lesions. Metformin, as an anti-diabetic agent, represents anti-angiogenic property. Here, we performed a study using human normal endometrial stromal cells (N-ESCs) from healthy endometrial tissue and human eutopic endometrial stromal cells (EU-ESCs) and ectopic endometrial stromal cells (ECT-ESCs) from endometriosis patients. ESCs were cultured and treated with different concentrations of Metformin (0-20 mmol/l) for 72 h to evaluate Metformin effect on cell viability, proliferation, migration was measured by methyl thiazolyl tetrazolium (MTT) assay and scratch test respectively as well as expression of angiogenesis and migration markers. The Metformin reduced cell migration, and proliferation of endometriotic stromal cells in a time and concentration dependently manner. Furthermore, Metformin attenuated the expression of angiogenic and inflammatory genes in human endometriotic stromal cells. The direct anti-proliferative effect on ECT-ESCs combined with the effects of Metformin on inflammatory and angiogenesis-related genes expression supports its therapeutic potential for endometriosis. Metformin could be used as an effective adjuvant in endometriosis treatment.

Exploring the role of Luman/CREB3 in regulating decidualization of mice endometrial stromal cells by comparative transcriptomics

Background

Luman is a member of CREB3 (cAMP responsive element-binding) subfamily of the basic leucine-zipper (bZIP) transcription factors. It may play an important regulatory role during the decidualization process since Luman was highly expressed in the decidual cells. However, the exact molecular mechanisms of how Luman regulating decidualization is unknown.

Results

Using an in vitro model, we prove that Luman knockdown significantly affects the decidualization process of mice endometrial stromal cells (ESCs) as the expression of two decidual markers PRL8a2 and PRL3c1 were repressed. We employed massively parallel RNA sequencing (RNA-Seq) to understand the changes in the transcriptional landscape associated with knockdown of Luman in ESCs during in vitro decidualization. We found significant dysregulation of genes related to protein processing in the endoplasmic reticulum (ER). Several genes involved in decidualization including bone morphogenetic proteins (e.g. BMP1, BMP4, BMP8A, BMP2, and BMP8B), growth factor-related genes (e.g. VEGFB, FGF10, and FGFR2), and transcription factors (IF4E, IF4A2, WNT4, WNT9A, ETS1, NOTCH1, IRX1, IDB1, IDB2, and IDB3), show altered expression. We also found that the knockdown of Luman is associated with increased expression of cell cycle-related genes including cycA1, cycB1, cycB2, CDK1, CDK2, and PLPK1, which resulted in an increased proportion of ESCs in the G1 phase. Differentially expressed genes (DEGs) were highly enriched on ECM-receptor interaction signaling, endoplasmic reticulum protein processing, focal adhesion, and PI3K-Akt signaling pathways.

Conclusions

Luman knockdown results in widespread gene dysregulation during decidualization of ESCs. Genes involved in protein processing in ER, bone morphogenetic protein, growth factor, and cell cycle progression were identified as particularly important for explaining the decidual deficiency observed in this in vitro model. Therefore, this study provides clues as to the underlying mechanisms that may expand our understanding of gene regulation during decidualization.

Dysregulation of miR-202-3p Affects Migration and Invasion of Endometrial Stromal Cells in Endometriosis via Targeting ROCK1

Dysregulation of microRNAs in endometrial cells plays a pivotal role in the pathogenesis of endometriosis (EM). This study aims to investigate the implication of aberrant miR-202-3p expression in EM and the underlying mechanisms. We demonstrated that miR-202-3p was significantly downregulated in eutopic endometrium of EM in comparison to normal endometrial samples (P < 0.05). Primary endometrial stromal cells (ESCs) isolated from eutopic or ectopic endometrium also showed a significant decrease in miR-202-3p level compared to ESCs from normal endometrium (P < 0.01). Functional studies using MTT, wound healing assay and transwell assay indicated that overexpression of miR-202-3p greatly impaired cell viability, migration, and invasion, whereas suppression of miR-202-3p exhibited the opposite effects (P < 0.05 or P < 0.01). miR-202-3p mimics or inhibitors transfection significantly decreased or increased expression of Rho-associated, coiled-coil containing protein kinase 1 (ROCK1), respectively, in ESCs (P < 0.01). Using dual luciferase reporter assay, we validated ROCK1 as a direct target of miR-202-3p. Moreover, negative correlations between miR-202-3p and ROCK1 mRNA/protein levels were determined in both eutopic and normal control endometrium (P < 0.01). In conclusion, these findings suggest that suppression of miR-202-3p in ESCs results in enhanced cell viability, invasion, and migration at least partially via upregulation of its target ROCK1, which eventually contributes to the development of endometriosis.

Integrins expressed on the surface of human endometrial stromal cells derived from a female patient experiencing spontaneous abortion

Here, as a basic study in revealing the correlation between extracellular matrix components and spontaneous abortion, we defined the types of integrins expressed on the surface of endometrial stromal (ES) cells retrieved from the uterus of a patient experiencing spontaneous abortion. For these, the types of integrin subunits in the ES cells retrieved from a woman with spontaneous abortion were identified at the transcriptional and translational levels, and functional assay was conducted for confirming the combinations of integrin α and β subunits. Among the genes encoding 25 integrin subunits, significantly high transcription was seen in integrins α₁, α₂, α₃, α₄, α₅, α_V, β₁, β₃, and β₅. Translation of integrins α₁, α₃, α₅, α_V, and β₁ on the cell surface was detected in almost all ES cells, whereas integrins α₂, α₄, β₃, and β₄ were expressed translationally only in some ES cells. Subsequently, ES cells showed significantly increased adhesion to collagen I, laminin, fibronectin, and vitronectin, and functional blocking of integrin α₁, α₃, α₅, and α_V significantly inhibited adhesion to these molecules. These results demonstrated that active heterodimers composed of integrins α₁β₁, α₃β₁, α₅β₁, and α_Vβ₁ were co-localized on the surface of ES cells derived from a patient experiencing spontaneous abortion.

Effects of COH on the expression of connexin43 in endometrial stromal cells

OBJECTIVE

The purpose of this study was to investigate the effect of controlled ovarian hyperstimulation (COH) on gap junction, and to induce the effect of an estrogen level overdose on gap junction in vitro by COH. Here, we mainly focus on connexion43 (Cx43), progesterone receptor (PR) and prolactin-related protein (PRP), and CyclinD3 genes expression, as well as the expression of Cx43 protein, were investigated.

MATERIALS AND METHODS

Mature BDF-1 mice were divided into different COH, and the mouse uterus was isolated, Paraffin sections evaluate the effect of COH on mouse uterine endometrial morphology. The other part was used for the extraction of mouse uterine endometrial stromal cells (ESC), some related gene changes are detected. Human ESC were isolated from human endometrium by primary culture, the estrogen concentrations 10^-6 mol/L, 10^-7 mol/L were added, the changes of Cx43 gene and related proteins were detected, too.

RESULTS

(1) HE staining showed that in the ovulatory endometrium of mice in the high super ovulation group, uterine glands in the stromal layer were significantly increased, the relative vascular tissues was less abundant. (2) In three groups of COH mice, the expression of Cx43, PR, and PRP genes in ESC was significantly different (P < 0.05). (3) In vitro ESC in the COH group showed significant differences in Cx43, PR, and CyclinD3 gene expression (P < 0.05), and showed an obvious dose effect. In addition, Western blot analysis showed that the Cx43 protein and Cx43 gene expression were similar.

CONCLUSIONS

(1) Animal experiments study showed that Cx43 gene expression in ESC was significantly decreased in hyper COH, in addition, the advance in gene expression was significantly earlier, suggesting decidualization appeared significantly earlier. (2) In vitro COH demonstrated when the estrogen concentration used was higher, the expression level of Cx43 gene and protein was lower. Combined with animal experiments, the endometrium decidualization was advanced in mice that were underwent hyper COH, which may reflect the endometrial receptivity.

Human Endometrial Stem Cell Isolation from Endometrium and Menstrual Blood

Human endometrial stem cell/stromal cells (hEnSCs) are isolated from endometrium or menstrual blood and are recognized as a valuable cell type in tissue engineering and cell therapy. Furthermore, hEnSCs, which have CD90 (a mesenchymal marker), CD105 (endoglin), CD44, CD146 (endometrial stem cell markers) and lack CD31 (Endothelial marker), CD34 (hematopoietic marker) and CD133 on the cell surface, are a new source of mesenchymal stem/stromal cells. Additionally, these cells can be encapsulated into self-assembling peptide nanofibers as a 3D scaffold for applications in the treatment of neurodegenerative diseases. Here, we describe a protocol to isolate hEnSCs from endometrium or menstrual blood.

Extended Culture of Encapsulated Human Blastocysts in Alginate Hydrogel Containing Decidualized Endometrial Stromal Cells in the Presence of Melatonin

Extended in vitro culture of human embryos beyond blastocyst stage could serve as a tool to explore the molecular and physiological mechanisms underlying embryo development and to identify factors regulating pregnancy outcomes. This study presents the first report on the maintenance of human embryo in vitro by alginate co-encapsulation of human blastocyst and decidualized endometrial stromal cells (EnSCs) under melatonin-fortified culture conditions. The effectiveness of the 3D culture system was studied through monitoring of embryo development in terms of survival time, viability, morphological changes, and production of the two hormones of 17b-oestradiol and human chorionic gonadotropin. The embryo structural integrity was preserved during alginate encapsulation; however, only 23 % of the encapsulated embryos could retain in the hydrogels over time and survived until day 4 post-encapsulation. The culture medium fortification with melatonin significantly elevated the maintenance rate of expanded embryos in alginate beads by 65 % and prolonged survival time of human embryos to day 5. Furthermore, embryo co-culture with EnSCs using melatonin-fortified medium increased the survival time of encapsulated embryos to 44 %. The levels of two measured hormones significantly rose at day 4 in comparison with day 2 post-encapsulation especially in the group co-encapsulated with EnSCs and cultivated in melatonin-fortified culture medium. These data are the first evidence representing in vitro development of human embryos until day 10 post-fertilization. This achievement can facilitate the investigation of the mechanisms regulating human embryo development.

Proliferation of mouse endometrial stromal cells in culture is highly sensitive to lysophosphatidic acid signaling

Endometrial stromal cells (ESCs) proliferate rapidly both in vivo and in vitro. Here we show that proliferation of ESCs in vitro is strongly dependent on lysophosphatidic acid (LPA) signaling. LPA is produced by autotaxin (ATX) and induces various kinds of cellular processes including migration, proliferation and inhibition of cell death possibly through six G protein-coupled receptors (LPA_1-6). We found that ESCs proliferated rapidly in vitro in an autocrine manner and that the proliferation was prominently suppressed by either an ATX inhibitor (ONO-8430506) or an LPA_1/3 antagonist (Ki16425). Among the cells lines tested, mouse ESCs were the most sensitive to these inhibitors. Proliferation of ESCs isolated from either LPA₁- or LPA₃-deficient mice was comparable to proliferation of ESCs isolated from control mice. An LPA receptor antagonist (AM095), which was revealed to be a dual LPA₁/LPA₃ antagonist, also suppressed the proliferation of ESCs. The present results show that LPA signaling has a critical role in the proliferation of ESCs, and that this role is possibly mediated redundantly by LPA₁ and LPA₃.