Angiotensin-(1-7) and angiotensin Ⅱ induce the transdifferentiation of human endometrial epithelial cells in vitro

Uncovering the role of TET2-mediated ENPEP activation in trophoblast cell fate determination

Early trophoblast differentiation is crucial for embryo implantation, placentation and fetal development. Dynamic changes in DNA methylation occur during preimplantation development and are critical for cell fate determination. However, the underlying regulatory mechanism remains unclear. Recently, we derived morula-like expanded potential stem cells from human preimplantation embryos (hEPSC-em), providing a valuable tool for studying early trophoblast differentiation. Data analysis on published datasets showed differential expressions of DNA methylation enzymes during early trophoblast differentiation in human embryos and hEPSC-em derived trophoblastic spheroids. We demonstrated downregulation of DNA methyltransferase 3 members (DNMT3s) and upregulation of ten-eleven translocation methylcytosine dioxygenases (TETs) during trophoblast differentiation. While DNMT inhibitor promoted trophoblast differentiation, TET inhibitor hindered the process and reduced implantation potential of trophoblastic spheroids. Further integrative analysis identified that glutamyl aminopeptidase (ENPEP), a trophectoderm progenitor marker, was hypomethylated and highly expressed in trophoblast lineages. Concordantly, progressive loss of DNA methylation in ENPEP promoter and increased ENPEP expression were detected in trophoblast differentiation. Knockout of ENPEP in hEPSC-em compromised trophoblast differentiation potency, reduced adhesion and invasion of trophoblastic spheroids, and impeded trophoblastic stem cell (TSC) derivation. Importantly, TET2 was involved in the loss of DNA methylation and activation of ENPEP expression during trophoblast differentiation. TET2-null hEPSC-em failed to produce TSC properly. Collectively, our results illustrated the crucial roles of ENPEP and TET2 in trophoblast fate commitments and the unprecedented TET2-mediated loss of DNA methylation in ENPEP promoter.

Improvement of vaginal probiotics Lactobacillus crispatus on intrauterine adhesion in mice model and in clinical practice

BACKGROUND

Intrauterine adhesion (IUA) is a frequent acquired endometrial condition, for which there is no effective preventive or treatment. Previous studies have found that vaginal microbiota dysregulation is closely related to endometrial fibrosis and IUA. Therefore, we wondered whether restoration of vaginal microbiota by vaginal administration of L. crispatus could prevent endometrial fibrosis and ameliorate IUA.

RESULTS

First, we created a mechanically injured mouse model of IUA and restored the mice's vaginal microbiota by the addition of L. crispatus convolvulus. The observations suggested that intrauterine injections of L. crispatus significantly decreased the degree of uterine fibrosis, the levels of IL-1β and TNF-α in blood, and downregulated the TGF-β1/SMADs signaling pathway in IUA mice. A therapy with L. crispatus considerably raised the abundance of the helpful bacteria Lactobacillus and Oscillospira and restored the balance of the vaginal microbiota in IUA mice, according to high-throughput sequencing. Then we conducted a randomized controlled trial to compare the therapeutic effect of L. crispatus with estrogen after transcervical resection of adhesion (TCRA). And the results showed that vaginal probiotics had a better potential to prevent intrauterine adhesion than estrogen.

CONCLUSIONS

This study confirmed that L. crispatus could restore vaginal microbiota after intrauterine surgery, inhibit endometrial fibrosis, and finally play a preventive and therapeutic role in IUA. At the same time, it is a new exploration for the treatment of gynecological diseases with vaginal probiotics.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn/ , identifier (ChiCTR1900022522), registration time: 15/04/2019.

Physiological and pathological roles of Ang II and Ang- (1-7) in the female reproductive system

The local Renin-Angiotensin System (RAS) has been demonstrated to exist in a wide range of tissues and organs, In the female reproductive system, it is mainly found in the ovary, uterus and placenta. The RAS system is made up of a series of active substances and enzymes, in addition to the circulating endocrine renin-angiotensin system. The active peptides Angiotensin II (Ang II) and Angiotensin (1-7) (Ang-(1-7)), in particular, appear to have distinct activities in the local RAS system, which also controls blood pressure and electrolytes. Therefore, in addition to these features, angiotensin and its receptors in the reproductive system seemingly get involved in reproductive processes, such as follicle growth and development, as well as physiological functions of the placenta and uterus. In addition, changes in local RAS components may induce reproductive diseases as well as pathological states such as cancer. In most tissues, Ang II and Ang- (1-7) seem to maintain antagonistic effects, but this conclusion is not always true in the reproductive system, where they play similar functions in some physiological and pathological roles. This review investigated how Ang II, Ang- (1-7) and their receptors were expressed, localized, and active in the female reproductive system. This review also summarized their effects on follicle development, uterine and placental physiological functions. The changes of local RAS components in a series of reproductive system diseases including infertility related diseases and cancer and their influence on the occurrence and development of diseases were elucidated. This article reviews the physiological and pathological roles of Ang II and Ang- (1-7) in female reproductive system,a very intricate system of tissue factors that operate as agonists and antagonists was found. Besides, the development of novel therapeutic strategies targeting components of this system may be a research direction in future.

Angiotensin-converting enzyme 2 (ACE2), angiotensin-(1-7) and Mas receptor in gonadal and reproductive functions

Angiotensin (Ang)-(1-7) is an active peptide formed from Ang I or Ang-(1-9) by multiple proteolytic steps involving angiotensin-converting enzyme (ACE) 1 and other peptidases, or by a single cleavage of Ang II catalyzed chiefly by ACE2. The effects of Ang-(1-7) are mediated by the G protein-coupled receptor Mas (or Mas1), encoded by the protooncogene MAS. The reproductive system expresses ACE2 quite abundantly and therefore is able to generate Ang-(1-7) using precursor peptides produced locally or taken from circulation. In several mammalian species, Ang-(1-7) stimulates ovarian follicle growth, oocyte maturation and ovulation. The peptide is found in human endometrium, mostly during the secretory phase of menstrual cycle when the uterus is receptive to embryo implantation. Rat models and human observational studies suggest that Ang-(1-7) is part of the maternal adaptive response to pregnancy and its deficiency is associated with poor circulation in the placental bed. Knockout mice revealed a relevant participation of Mas-mediated stimulus to the maintenance of normal spermatogenesis, even though the animal can still reproduce without it. In addition, the vasorelaxant effect of Ang-(1-7) participates in the physiological mechanism of corpus cavernosum blood influx and penile erection. We conclude that preclinical evidence encourages the pursuit of treatments for female and male reproductive dysfunctions based on Mas agonists, starting with its natural ligand Ang-(1-7).

Transplantation of Human Amnion Epithelial Cells Improves Endometrial Regeneration in Rat Model of Intrauterine Adhesions

Intrauterine adhesions (IUAs) are characterized by the injury of endometrium due to curettage and/or endometritis. The loss of functional endometrium in uterine cavity usually results in hypomenorrhea, amenorrhea, infertility, and/or recurrent pregnancy loss. Recently, stem cell transplantation has been applied to promote the endometrial regeneration. Human amnion epithelial cells (hAECs) have been shown to have stem cell characteristics. In this study, we found that PKH26-labeled hAECs were mainly distributed in the basal layer of endometrium after transplantation, and hAEC transplantation, including uterine injection and tail vein injection, could increase pregnancy rate and the number of embryos in rat model of IUAs. Moreover, hAEC transplantation was demonstrated to increase the endometrial thickness, promote the proliferation of glands and blood vessels, and decrease fibrotic areas in the endometrium. The immunohistochemical and quantitative polymerase chain reaction analysis showed the upregulated expression of growth factors, such as basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), insulin-like growth factor-1 (IGF-1) after hAEC transplantation; and the downregulated expression of collagen type I alpha 1 (COL1A1), tissue inhibitor of metalloproteinase-1 (TIMP-1), and transforming growth factor-β (TGF-β), all of which are associated with the extracellular matrix (ECM) deposition after hAEC transplantation. The mRNA sequencing indicated that platelet-derived growth factor-C (PDGF-C), thrombospondin-1 (THBS1), connective tissue growth factor (CTGF), Wnt5a, and Snai2 were significantly modulated in treatment groups. These results indicate that hAEC transplantation promotes endometrial regeneration and the restoration of fertility in rat model of IUAs.

Potential influence of COVID-19/ACE2 on the female reproductive system

The 2019 novel coronavirus (2019-nCoV) appeared in December 2019 and then spread throughout the world rapidly. The virus invades the target cell by binding to angiotensin-converting enzyme (ACE) 2 and modulates the expression of ACE2 in host cells. ACE2, a pivotal component of the renin-angiotensin system, exerts its physiological functions by modulating the levels of angiotensin II (Ang II) and Ang-(1-7). We reviewed the literature that reported the distribution and function of ACE2 in the female reproductive system, hoping to clarify the potential harm of 2019-nCoV to female fertility. The available evidence suggests that ACE2 is widely expressed in the ovary, uterus, vagina and placenta. Therefore, we believe that apart from droplets and contact transmission, the possibility of mother-to-child and sexual transmission also exists. Ang II, ACE2 and Ang-(1-7) regulate follicle development and ovulation, modulate luteal angiogenesis and degeneration, and also influence the regular changes in endometrial tissue and embryo development. Taking these functions into account, 2019-nCoV may disturb the female reproductive functions through regulating ACE2.

Angiotensin peptides in the non-gravid uterus: Paracrine actions beyond circulation

The renin-angiotensin system (RAS) involves a complex network of precursors, peptides, enzymes and receptors comprising a systemic (endocrine) and a local (paracrine/autocrine) system. The local RAS plays important roles in tissue modulation and may operate independently of or in close interaction with the circulatory RAS, acting in a complementary fashion. Angiotensin (Ang) II, its receptor AT₁ and Ang-(1-7) expression in the endometrium vary with menstrual cycle, and stromal cell decidualization in vitro is accompanied by local synthesis of angiotensinogen and prorenin. Mas receptor is unlikely to undergo marked changes accompanying the cyclic ovarian steroid hormone fluctuations. Studies investigating the functional relevance of the RAS in the non-gravid uterus show a number of paracrine effects beyond circulation and suggest that RAS peptides may be involved in the pathophysiology of proliferative and fibrotic diseases. Endometrial cancer is associated with increased expression of Ang II, Ang-converting enzyme 1 and AT₁ in the tumoral tissue compared to neighboring non-neoplastic endometrium, and also with a gene polymorphism that enhances AT₁ signal. Ang II induces human endometrial cells to transdifferentiate into cells with myofibroblast phenotype and to synthetize extracellular matrix components that might contribute to endometrial fibrosis. Altogether, these findings point to a fully operating RAS within the uterus, but since many concepts rely on preliminary evidence further studies are needed to clarify the role of the local RAS in uterine physiology and pathophysiology.

Prevalence and Impact of Chronic Endometritis in Patients With Intrauterine Adhesions: A Prospective Cohort Study

STUDY OBJECTIVE

To evaluate the prevalence and impact of chronic endometritis (CE) in patients with intrauterine adhesions (IUAs).

DESIGN

Prospective cohort study (Canadian Task Force classification II-2).

SETTING

University-affiliated hospital.

PATIENTS

Eighty-two women with moderate to severe IUAs.

INTERVENTIONS

Transcervical resection of adhesions (TCRA) and endometrial biopsy were performed in all patients. According to results of the endometrial biopsy, participants were classified into 2 groups: 29 patients with CE (CE group) and 53 women without CE (NCE group). Second-look hysteroscopy assessed the impact of TCRA using the American Fertility Society classification system.

MEASUREMENTS AND MAIN RESULTS

Prevalence of CE, reformation of adhesions, and reduction of adhesion score were studied. Thirty-one women (37.8%) presented with visual signs of CE at hysteroscopy, confirmed by histology in 29 of 82 patients (35.4%). In hysteroscopic diagnosis of CE, sensitivity and specificity were 79.3% (23/29) and 84.9% (45/53), respectively. At second-look hysteroscopy, the recurrence of adhesions in the CE group was significantly higher than in the NCE group (44.8% vs 20.8%, respectively; p = .022). The median reduction of adhesion score was significantly greater in the NCE group (median, 8; range, 0-12) than in the CE group (median, 5; range, 0-10).

CONCLUSION

CE in women with IUAs may be a contributing factor in higher adhesion recurrence, indicating chronic inflammation may play a role in IUA recurrence. (Clinical Trial Registration No.: NCT02744807.).

Angiotensin II promotes endometrial cancer cell survival

Endometrial cancer (EC) is one of the most common female cancers. One of the key processes involved in EC development is uncontrolled proliferation stimulated by local factors such as angiotensin. The aim of the present study was to evaluate the influence of angiotensin II (Ang II) on human EC cells. Biological assays and gene expression analysis were performed on three cell lines: ISH, MFE-296 and MFE-280. Our results indicated that at the beginning of cancerogenesis Ang II induced abnormal proliferation at lower doses. We also showed that dose-dependent induction of proliferation was connected with changes in the expression of MKI67, CCND1 and CCNE1 genes in well- and poorly differentiated cancer cells. After Ang II treatment, poorly differentiated endometrial cancer cell line acquired a mesenchymal phenotype, which was characterized by induced expression of EMT-related genes (VIM, CD44, SNAI1, ZEB1 and ZEB2). Our study revealed that Ang II influences EC cells in terms of cancer-related processes, and is responsible for increased proliferation, reduction in apoptosis, increased mobility and modulation of adhesion potential. Its effect and effectiveness appear to be highly connected with the differentiation status of the cancerous cells, as Ang II appears to play a crucial role in the early and late stages of malignant transformation.

MicroRNA-29b Inhibits Endometrial Fibrosis by Regulating the Sp1-TGF-β1/Smad-CTGF Axis in a Rat Model

Intrauterine adhesions (IUAs), which are characterized by endometrial fibrosis, increase the risk of secondary infertility and recurrent miscarriage. MicroRNA-29 (miR-29) is a potent inhibitor of TGF-β1/Smad signaling. In this study, we investigated the therapeutic potential of agomir-29b, an miR-29b mimic, in endometrial fibrosis induced by dual injury (uterine curettage and lipopolysaccharide treatment) in a rat model of IUA and explored the underlying mechanism. We found that injured rats developed endometrial fibrosis characterized by increased COL1A1 and α-smooth muscle actin expression and decreased E-cadherin expression, associated with a loss of miR-29b. Overexpression of miR-29b before injury prevented endometrial fibrosis including collagen accumulation and epithelial-mesenchymal transition. Delay of agomir-29b treatment until endometrial fibrosis was established on day 4 also halted the progression of disease. Further experiments indicated that miR-29b inhibited endometrial fibrosis via blockade of the Sp1-TGF-β1/Smad-CTGF pathway. In conclusion, agomir-29b may act as a novel and effective therapeutic agent against IUAs.