Clinical consequences of defective decidualization

Characteristics in patients with unexplained recurrent spontaneous abortion and the impact on immune, coagulation, and inflammatory profiles

OBJECTIVE

Unexplained Recurrent Spontaneous Abortion (RSA) impacts the physical and psychological well-being of women of reproductive age. This study aimed to reveal the potential mechanisms behind unexplained RSA from the perspective of glucose and lipid metabolic profiles before conception and their relationship with immune, coagulation, and inflammatory markers.

METHODS

A retrospective analysis was conducted on 100 patients with unexplained recurrent spontaneous abortion at our gynecology department from June 2022 to June 2023. According to whether abnormal glucose and lipid metabolism exist, patients were grouped into normal group and abnormal group. The study compared the glucose and lipid metabolic characteristics, immune status, coagulation, and inflammatory parameters between two groups.

RESULTS

The Abnormal Group exhibited higher fasting blood glucose, 2-hour oral glucose tolerance test, homeostatic model assessment of insulin resistance, total cholesterol, and LDL cholesterol, along with lower levels of HDL cholesterol. Additionally, alterations in immune profile parameters, including lower levels of CD4+ T cells, CD8+ T cells, B cells, NK cells, and elevated IL-6, were observed in the Abnormal Group. Regarding coagulation and inflammatory profile parameters, the Abnormal Group demonstrated prolonged prothrombin time, activated partial thromboplastin time, elevated fibrinogen and D-dimer levels, and increased platelet count, along with elevated C-reactive protein, TNF-α, and IL-1β levels. Correlation analysis revealed significant associations between the pre-pregnancy metabolic characteristics and immune, coagulation, and inflammatory profile parameters.

CONCLUSION

Abnormal glucose and lipid metabolism may lead to or exacerbate unexplained RSA in some patients, and therapeutic interventions targeting glucose and lipid metabolism hold promise for improving pregnancy outcomes in this population.

Studys on the effect of decidual stromal cells and trophoblast cells on cytokine secretion by decidual NK cells

Unexplained recurrent pregnant loss (URPL) is associated with immune imbalance at the maternal-fetal interface. Decidual immune cells regulate the response of the maternal immune system to the fetus. However, the effect of decidual stromal cells (DSCs) and trophoblast cells on cytokine secretion by decidual NK cells remains unclear. In this study, we investigated the influence of JEG-3 cells and DSCs on the secretion of cytokines in dNK cells. Furthermore, we investigated whether or not cytokine secretion was regulated by the mitogen-activated protein kinase (MAPK) signaling pathway at the maternal-fetal interface. Our study showed that the secretions of both IFN-γ and TNF-α in dNK cells in URPL were significantly higher than those in normal pregnancy. In the coculture of JEG-3, DSCs, and dNK cells, IL-10 and IL-4 production increased in dNK cells during normal pregnancy; whereas IFN-γ and TNF-α production increased but IL-10 and IL-4 levels decreased during URPL. Furthermore, pretreatment with P38/MAPK inhibition significantly inhibited the secretion of NK1- and NK2-type cytokines in the coculture of the three types of cells. Our study elucidated the influence of trophoblasts and DSCs on the expression of cytokines in dNK cells in patients with URPL and uncovered a complicated crosstalk through the MAPK signal at the maternal-fetal interface.

Higher sperm H3K4me3 levels are associated with idiopathic recurrent pregnancy loss

During fertilization, spermatozoa contribute genetic and epigenetic factors such as chromatin packaged with protamines and histones; DNA methylome, non-coding RNAs, etc. Human sperm chromatin retains 5-15% nucleosomes which can play a key role in embryonic development. Recurrent pregnancy loss (RPL) is a condition mainly attributed to defects in embryo and placenta development. Majority of the known RPL factors are of maternal contribution, while  ~50% RPL cases are termed idiopathic (iRPL). In addition to paternal genetic factors, epigenetic factors via sperm could also be responsible for iRPL. Hence, we investigated alterations in retained nucleosome content of iRPL sperm (n = 46) as compared to fertile male population (n = 40). We measured the relative abundance of core histone H4 and Protamine-2 content along with the modified histones H4Ac, H3K4me3, H3K27me3 and H3K9me3 by flow cytometry. H4 and Protamine-2 levels were comparable in both groups and showed significant negative correlation. The iRPL group had significantly higher levels of sperm H3K4me3 as compared to the fertile control group. The other modified histones and protamine levels showed no significant alterations. Furthermore, sperm DFI was found to be significantly positively correlated with H4 levels in both groups. No significant correlation was observed between sperm 5-mC levels with H4 and other modified histone levels. A fraction of H3K4me3 enrichment is now known to resist embryonic epigenetic reprogramming; and hence, such elevated levels in the sperm would question its developmental competence leading to RPL pathology. Also, incidence of sperm DNA fragmentation is associated with increased histone retention in both fertile and iRPL cases.

Role of uterine NK cells in pregnancy complication

Remodeling of blood vessels and angiogenesis play a critical role in the pregnancy process, particularly at the implantation site. Both the innate and adaptive immune systems, especially uterine natural killer (uNK) cells, are involved in this process. During the first trimester, uNK cells constitute approximately 70 % of decidual leukocytes and are differentiated from CD34+ progenitor cells. In comparison to peripheral blood NK cells, uNK cells secrete specific cytokines that promote tissue remodeling while exhibiting lower cytotoxic activity. Any disturbance in the function of uNK cells or dysregulation of their receptors can lead to reproductive failures. This review focuses on the role of uNK cells in pregnancy disorders such as preeclampsia, recurrent pregnancy loss, and endometriosis. The findings of this research will assist researchers in targeting specific checkpoints to address pregnancy disorders in clinical settings. SIGNIFICANCE STATEMENT: In this study, we highlight the evidence that NK cells play a pivotal role in pregnancy disorders and appropriate phenotype and normal expression of receptors on uNK cells affected pregnancy outcomes. In summary, arterial remodeling and correct implantation are related to the presence of various cytokines and factors in the uterine microenvironment. Collectively, it seems that the result of this study can be helpful in clinic. In the other word, specialist can use appropriate drugs in infertility.

Macrophage at maternal-fetal Interface: Perspective on pregnancy and related disorders

Immune cells at the maternal-fetal interface (MFI) undergo dynamic changes to facilitate fetal growth and development during pregnancy. In contrast to the adaptive immune system, where effector T cells, Tregs, and suppressor T cells play key roles in maintaining immune tolerance toward the semi-allogeneic fetus, the innate immune system-comprising decidual nature killer (dNK) cells, macrophages, and dendritic cells (DCs)-makes up a significant portion of the decidual leukocyte population. These innate immune cells are crucial in modulating trophoblast invasion, spiral artery remodeling, and apoptotic cell phagocytosis. Dysregulation of the innate immune system has been linked to impaired uterine vessel remodeling and defective trophoblast invasion, which can lead to complications such as spontaneous abortion, preeclampsia (PE), and preterm. This review focuses on recent advancements in understanding the innate immune defenses at the maternal-fetal interface and their connections to pregnancy-related diseases, with particular emphasis on the role of macrophages.

Revolutionizing Implantation Studies: Uterine-Specific Models and Advanced Technologies

Implantation is a complex and tightly regulated process essential for the establishment of pregnancy. It involves dynamic interactions between a receptive uterus and a competent embryo, orchestrated by ovarian hormones such as estrogen and progesterone. These hormones regulate proliferation, differentiation, and gene expression within the three primary uterine tissue types: myometrium, stroma, and epithelium. Advances in genetic manipulation, particularly the Cre/loxP system, have enabled the in vivo investigation of the role of genes in a uterine compartmental and cell type-specific manner, providing valuable insights into uterine biology during pregnancy and disease. The development of endometrial organoids has further revolutionized implantation research. They mimic the native endometrial structure and function, offering a powerful platform for studying hormonal responses, implantation, and maternal-fetal interactions. Combined with omics technologies, these models have uncovered the molecular mechanisms and signaling pathways that regulate implantation. This review provides a comprehensive overview of uterine-specific genetic tools, endometrial organoids, and omics. We explore how these advancements enhance our understanding of implantation biology, uterine receptivity, and decidualization in reproductive research.

Exposure to Bisphenol A jeopardizes decidualization and consequently triggers preeclampsia by up-regulating CYP1B1

Preeclampsia (PE) is a pregnancy-related disease that poses a significant threat to the health of both the mother and the fetus. Previous studies have primarily focused on the role of the placenta in PE pathogenesis; however, normal decidualization is crucial for the subsequent development of the placenta and pregnancy. Bisphenol A (BPA) is an environmental endocrine disruptor commonly used in the synthesis of polycarbonate and epoxy resins. Overexposure to BPA can result in severe reproductive issues. To further investigate the effects of BPA exposure on pregnancy, C57BL/6 mice were continuously exposed to either 0 or 100 mg/kg of BPA in this study. As a result, these mice developed symptoms of hypertension and proteinuria, indicative of PE. Additionally, their decidualization process was impaired. Transcriptome sequencing of artificially induced decidua revealed a significant upregulation in the expression of CYP1B1 within the BPA-treated group. This upregulation accelerated the metabolism of estrogen and progesterone, leading to significant decreases in their levels. Furthermore, the expression levels of estrogen and progesterone receptors and their responding genes were significantly reduced. These findings suggest that BPA exposure can negatively impact decidualization and placental development, potentially contributing to the development of PE.

NK cells: shielding senescence homeostasis in the decidua during early pregnancy

Decidualization, the transformation of endometrial stromal cells into specialized decidual cells, is essential for embryo implantation and pregnancy maintenance. This process involves immune cell infiltration, especially decidual natural killer (dNK) cells, which regulate immune responses and support tissue remodeling. Recent findings suggest that cellular senescence during decidualization is not just a byproduct but plays a functional role in enhancing uterine receptivity. However, excessive senescence leads to complications like recurrent pregnancy loss. dNK cells help maintain decidual homeostasis by clearing senescent cells, preventing their harmful accumulation. The balance between dNK activity and decidual stromal cell (DSC) senescence is crucial for successful implantation and pregnancy outcomes. Disruption of this balance may contribute to pathological conditions. This review delves into the pivotal roles of dNK cells in decidual senescence regulation and discusses therapeutic strategies targeting senescence to improve pregnancy outcomes, and new approaches for treating reproductive disorders.

Immune Treatment Strategies in Unexplained Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) is characterized by the occurrence of two or more consecutive pregnancy losses. Approximately half of these cases lack a clear etiology and are termed unexplained recurrent pregnancy loss (URPL). Maternal-fetal immune dysfunction is thought to be involved in causing URPL. Increased human leukocyte antigen compatibility, susceptibility genes, lack of blocking antibodies, and dysfunction of immune cells can all disrupt the immune tolerance environment of the maternal-fetal interface. To correct the maternal-fetal immune imbalances, some immunotherapies were recently tried to be used for patients with URPL. This review summarizes the characteristics and mechanisms of the immune microenvironment at the maternal-fetal interface of URPL patients, and the present immunotherapies for URPL patients, to serve as a reference for future research.

The effect of the number of endometrial CD138+ cells on the pregnancy outcomes of infertile patients in the proliferative phase

Objective

This study was conducted to determine the influence of the number of CD138+ cells in the proliferative endometrium on pregnancy outcomes.

Methods

This retrospective cohort study was conducted from January to August 2018. A total of 664 infertile women who were not diagnosed with chronic endometritis (CE) and who had not received the respective antibiotic treatment were studied. Immunostaining was performed for the plasmacyte marker CD138. The number of CD138+ cells was compared in the proliferative and mid-luteal phases of the same patients without antibiotic therapy. Infertile patients were separated into three groups based on the number of positive lesions [the number of high power fields (HPFs) containing no less than five CD138+ cells]: 0 (n = 474), 1-2 (n = 125), and ≥3 positive lesions (n = 104). The pregnancy outcomes of the infertile women undergoing in vitro fertilization-embryo transfer (IVF-ET) among the three groups were then compared.

Results

There was a much higher level of CD138+ cells during proliferation than during the mid-luteal phase (P <0.0001). Pregnancy outcomes did not differ between the groups with 0 and 1-2 positive lesions. However, the ≥3 positive lesions group (P =0.006, P =0.029) had significantly lower ongoing pregnancy and live birth rates compared with the no positive lesion group. Although the 0 and ≥3 positive lesions groups showed a trend toward higher rates of clinical pregnancy (P =0.132), these differences failed to reach statistical significance. After age, body mass index (BMI), and clinical features were adjusted for, the ≥3 positive lesions group showed significantly lower live birth rates (aOR, 1.84; 95%CI, 1.08-3.15; P =0.026), clinical pregnancy (adjusted odds ratio (aOR), 1.78; 95% CI, 1.06-2.95; P =0.028), and ongoing pregnancy (aOR, 1.85; 95% CI, 1.09-3.15; P =0.024). The analysis demonstrated that the smallest number of stromal CD138+ cells suggestive of CE patients requiring treatment was defined as ≥ 3 positive lesions during the proliferation.

Conclusions

Different diagnostic criteria for CE should be created for the proliferative and mid-luteal phases. The analysis demonstrated that the smallest number of stromal CD138+ cells suggestive of CE patients was defined as ≥ 3 positive lesions during the proliferative phase.

Association of Arachidonic Acid Metabolism Related Genes With Endometrial Immune Microenvironment and Oxidative Stress in Coupes With Recurrent Implantation Failure

BACKGROUND

Alterations in lipid metabolism were reported to impact human fertility; however, there is limited evidence on the association of lipid metabolism with embryo implantation as well as the etiology of recurrent implantation failure (RIF), especially regarding arachidonic acid metabolism.

METHODS

Experimental verification research (16 RIF patients and 30 control patients) based on GEO database analysis (24 RIF patients and 24 control patients). The methods in bioinformatics included differential gene screening, functional enrichment analysis, protein-protein interaction network, cluster analysis, weighted gene co-expression network analysis, and so forth. RIF patients were recruited for the experimental validation section. The endometrial samples in the mid-luteal phase were collected and subjected to quantitative real-time PCR detection.

RESULTS

Genes related to oxidative stress were differentially expressed and 17 different types of immune cells exhibited diverse infiltration in three RIF subgroups with different arachidonic acid metabolism. HPGDS, ALOX12, and TBXAS1 showed a strong positive correlation with the infiltration of NK cell, on the contrary, GGT6, PLA2G12A, and PTGS2 showed a strong negative correlation. The overall expression of AAMRGs was positively correlated with the infiltration of activated CD8 T cell, macrophage, natural killer cell, and T follicular helper cell.

CONCLUSIONS

The cluster of arachidonic acid metabolism-related genes (AAMRGs) was abnormally expressed and positively associated with excessive oxidative stress as well as extensive infiltration of immune cells, including NK cells among RIF patients. Considering the high heterogeneity of the etiology of RIF, our study utilized the expression of AAMRGs as a typing basis to provide a new understanding of endometrial receptivity from the perspective of lipid metabolism and immune regulation in unexplained RIF couples, providing directions for its etiology and future basic research.

The landscape of recurrent spontaneous abortion registered on clinical trials.gov

Objective

Recurrent spontaneous abortion (RSA) presents a significant challenge in the field of reproductive medicine, as effective treatments remain limited despite extensive research efforts. A comprehensive understanding of current RSA clinical trials is essential for enhancing trial design and identifying existing research gaps. The aim of this study is to characterize RSA related clinical trials registered on Clinical Trials.gov.

Methods

A thorough search was conducted to identify and review clinical trials focusing on RSA that were registered on Clinical Trials.gov up to March2, 2024.

Results

A total of 138 trials were identified in the analysis, with 72 (52.17%) classified as intervention trials and 66 (47.83%) as observational trials. Approximately half of the studies (67,48.55%) had an enrollment of 100 participants or fewer. The majority of trials included only female participants. Asia hosted the highest number of clinical trials (46,33.33%), followed by Europe (36,26.09%), Africa (29,21.01%), America (13,9.42%). The majority of trials (61,44.20%) focused on individuals with unexplained recurrent spontaneous abortion (URSA). The predominant intervention types examined in the reviewed studies were drug interventions (49,62.82%), with a notable rise in behavioral intervention trials.

Conclusion

Our research findings suggest that existing research efforts in the realm of RSA are inadequate for the progression of prevention and treatment strategies. The majority of clinical trials have primarily targeted individuals with URSA, with a particular emphasis on drug interventions, notably anticoagulants.

Mechanism of Endometrial Receptivity Affected by Fibroids

Fibroids are the most common benign tumors of the female reproductive system. Most patients with fibroids are asymptomatic, but the presence of fibroids can still cause some abnormal clinical symptoms, such as increased menstrual volume, abnormal uterine bleeding, pelvic pain, urinary tract and gastrointestinal tract compression symptoms, etc. The impact of fibroids on pregnancy is worth discussing. At present, it is believed that submucosal myoma and intramural myoma affecting uterine cavity shape affect the pregnancy outcome of patients, while the impact of type III intramural myoma on pregnancy is still controversial. A number of studies have found that in addition to direct contact with the endometrial compression, uterine myoma also affects the endometrial flexibility through other ways. In this review, we summarized the effects of fibroids on endometrial receptivity and discussed in depth the mechanisms of such effects, including secretion of cytokines, changes in endometrial blood flow and angiogenesis, effects on endometrial peristalsis and mechanical stress conduction, changes in uterine microecological environment, and abnormal signal transduction pathways. Understanding the mechanism of endometrial receptivity affected by fibroids is significant for exploring the treatment of fibroids, improving the pregnancy outcome of patients with fibroids and increasing the clinical pregnancy rate.

Temporal and Spatial Variation of the Human Placental Microbiota During Pregnancy

PROBLEM

Previously believed sterile, the placenta hosts distinct microbial species across various locations. This study aims to elucidate the temporal and spatial variations of placental microbiota throughout gestation, addressing gaps in current understanding.

METHOD OF STUDY

A case-control study at a single-center compared microbial profiles in pregnant women delivering preterm (<37 weeks) or at term (>37 weeks) across placental sites: basal plate, fetal membranes, and placental villous. Microbial abundance and diversity were evaluated using QIIME and the R package "Phyloseq," while Q-PCR with specific primers validated absolute abundance in samples.

RESULTS

We found no alteration in bacterial communities based on delivery mode across all samples. Q-PCR detected low-abundance bacteria, notably enriched in preterm samples, especially in early preterm cases. Throughout gestation, bacterial composition varied, with increasing levels of Proteobacteria and Firmicutes observed in the placenta. Significant differences in bacterial profiles were noted across locations and gestational stages, with Ralstonia insidiosa consistently present in the basal plate throughout gestation. Species-specific Q-PCR confirmed the presence of Ralstonia and revealed an inverse relationship between Streptococcus agalactiae and pregnancy progression.

CONCLUSIONS

The placenta hosts its own microbiome, with distinct profiles observed between term and preterm samples. Further research is needed to clarify the impact of bacterial dysbiosis on preterm birth and develop methods to distinguish pathological bacteria from the natural microbiome.

Scoping Review of Microbiota Dysbiosis and Risk of Preeclampsia

Limited studies have investigated the role of the microbiota in hypertensive disorders of pregnancy (HDP), particularly preeclampsia, which often results in preterm birth. We evaluated 23 studies that explored the relationship between gut, vaginal, oral, or placental microbiotas and HDP. Scopus, ProQuest Health Research Premium Collection, ProQuest Nursing & Allied Health Database, EBSCO, and Ovid were searched for relevant literature. Majority (18) of studies focused on the gut microbiota, and far fewer examined the oral cavity (3), vagina (3), and placenta (1). One study examined the gut, oral, and vaginal microbiotas. The consensus highlights a potential role for microbiota dysbiosis in preeclampsia and HDP. Especially in the third trimester, preeclampsia is associated with gut dysbiosis-deficient in beneficial species of Akkermansia, Bifidobacterium, and Coprococcus but enriched with pathogenic Campylobacterota and Candidatus Saccharibacteria, with low community α-diversity. Similarly, the preeclamptic vaginal and oral microbiotas are enriched with bacterial vaginosis and periodontal disease-associated species, respectively. The trend is also observed in the placenta, which is colonized by gastrointestinal, respiratory tract, and periodontitis-related pathogens. Consequently, a chronic proinflammatory state that adversely impacts placentation is implicated. These observations however require more mechanistic studies to establish the timing of the preceding immune dysfunction and any causality.

Whole exome sequencing identifies a novel mutation in Annexin A4 that is associated with recurrent spontaneous abortion

Background

Recurrent spontaneous abortion (RSA) is a multifactorial disease, the exact causes of which are still unknown. Environmental, maternal, and genetic factors have been shown to contribute to this condition. The aim of this study was to investigate the presence of mutations in the ANXA4 gene in patients with RSA.

Methods

Genomic DNA was extracted from 325 patients with RSA and 941 control women with a normal reproductive history for whole-exome sequencing (WES). The detected variants were annotated and filtered, and the pathogenicity of the variants was predicted through the SIFT online tool, functional enrichment analyses, Sanger sequencing validation, prediction of changes in protein structure, and evolutionary conservation analysis. Furthermore, plasmid construction, Western blotting, RT-qPCR, and cell migration, invasion and adhesion assays were used to detect the effects of ANXA4 mutations on protein function.

Results

An ANXA4 mutation (p.G8D) in 1 of the 325 samples from patients with RSA (RSA-219) was identified through WES. This mutation was not detected in 941 controls or included in public databases. Evolutionary conservation analysis revealed that the amino acid residue affected by the mutation (p.G8D) was highly conserved among 13 vertebrate species, and the SIFT program and structural modeling analysis predicted that this mutation was harmful. Furthermore, functional assays revealed that this mutation could inhibit cell migration, invasion and adhesion.

Conclusion

Our study suggests that an unreported novel ANXA4 mutation (p.G8D) plays an important role in the pathogenesis of RSA and may contribute to the genetic diagnosis of RSA.

Chronic endometritis and recurrent reproductive failure: a systematic review and meta-analysis

Background

The endometrium holds a crucial role in reproduction by supporting blastocyst adhesion, cytotrophoblast invasion and fetal development. Among the various uterine disorders, endometritis, particularly chronic endometritis (CE), has gained attention due to its association with adverse reproductive outcomes (recurrent pregnancy loss (RPL), recurrent implantation failure (RIF), and infertility). The association between CE and adverse reproductive outcomes stresses the necessity for comprehensive diagnostic and therapeutic strategies to optimize fertility outcomes and support individuals in their journey towards parenthood.

Aim

To explore the relationship between CE and reproductive disorders.

Methods

Following PRISMA guidelines, a systematic review and meta-analysis using published data from 1990 to 2024 were carried out.

Results

A population of 1,038 women was included. Regarding CE-infertility association, a positive correlation was found, with 19.46% CE rate in infertile women compared to 7.7% in controls (OR: 2.96, 95% CI 1.53-5.72, p 0.001). No significant association was observed between RIF and CE (OR: 1.10, 95% CI 0.26-4.61, p 0.90), CE rates in both groups were relatively comparable, with 6.35% in women with RIF and 5.8% in controls. On the opposite, a strong association between CE and RPL was found, reporting a CE rate of 37.6% in RPL cases compared to 16.4% in controls (OR: 3.59, 95% CI 2.46-5.24, p < 0.00001).

Conclusions

CE appears to be associated to infertility and RPL, while no significant association was noted in cases of RIF.

Systematic review registration

https://www.crd.york.ac.uk/prospero/#recordDetails PROSPERO, identifier CRD42024541879.

3DMOUSEneST: a volumetric label-free imaging method evaluating embryo-uterine interaction and decidualization efficacy

Effective interplay between the uterus and the embryo is essential for pregnancy establishment; however, convenient methods to screen embryo implantation success and maternal uterine response in experimental mouse models are currently lacking. Here, we report 3DMOUSEneST, a groundbreaking method for analyzing mouse implantation sites based on label-free higher harmonic generation microscopy, providing unprecedented insights into the embryo-uterine dynamics during early pregnancy. The 3DMOUSEneST method incorporates second-harmonic generation microscopy to image the three-dimensional structure formed by decidual fibrillar collagen, named 'decidual nest', and third-harmonic generation microscopy to evaluate early conceptus (defined as the embryo and extra-embryonic tissues) growth. We demonstrate that decidual nest volume is a measurable indicator of decidualization efficacy and correlates with the probability of early pregnancy progression based on a logistic regression analysis using Smad1/5 and Smad2/3 conditional knockout mice with known implantation defects. 3DMOUSEneST has great potential to become a principal method for studying decidual fibrillar collagen and characterizing mouse models associated with early embryonic lethality and fertility issues.

Quercetin enhances decidualization through AKT-ERK-p53 signaling and supports a role for senescence in endometriosis

BACKGROUND

Patients with endometriosis suffer with chronic pelvic pain and infertility, and from the lack of pharmacologic therapies that consistently halt disease progression. Differences in the endometrium of patients with endometriosis vs. unaffected controls are well-documented. Specifically, shed endometrial tissues (delivered to the pelvic cavity via retrograde menstruation) reveal that a subset of stromal cells exhibiting pro-inflammatory, pro-fibrotic, and pro-senescence-like phenotypes is enhanced in endometriosis patients compared to controls. Additionally, cultured biopsy-derived endometrial stromal cells from endometriosis patients exhibit impaired decidualization, a defined differentiation process required for human embryo implantation and pregnancy. Quercetin, a senolytic agent, shows therapeutic potential for pulmonary fibrosis, a disorder attributed to senescent pulmonary fibroblasts. In rodent models of endometriosis, quercetin shows promise, and quercetin improves decidualization in vitro. However, the exact mechanisms are not completely understood. Therefore, we investigated the effects of quercetin on menstrual effluent-derived endometrial stromal cells from endometriosis patients and unaffected controls to define the signaling pathways underlying quercetin's effects on endometrial stromal cells.

METHODS

Menstrual effluent-derived endometrial stromal cells were collected and cultured from unaffected controls and endometriosis patients and then, low passage cells were treated with quercetin (25 µM) under basal or standard decidualization conditions. Decidualization responses were analyzed by measuring the production of IGFBP1 and PRL. Also, the effects of quercetin on intracellular cAMP levels and cellular oxidative stress responses were measured. Phosphokinase arrays, western blotting, and flow cytometry methods were performed to define the effects of quercetin on various signaling pathways and the potential mechanistic roles of quercetin.

RESULTS

Quercetin significantly promotes decidualization of control- and endometriosis-endometrial stromal cells. Quercetin substantially reduces the phosphorylation of multiple signaling molecules in the AKT and ERK1/2 pathways, while enhancing the phosphorylation of p53 and total p53 levels. Furthermore, p53 inhibition blocks decidualization while p53 activation promotes decidualization. Finally, we provide evidence that quercetin increases apoptosis of endometrial stromal cells with a senescent-like phenotype.

CONCLUSIONS

These data provide insight into the mechanisms of action of quercetin on endometrial stromal cells and warrant future clinical trials to test quercetin and other senolytics for treating endometriosis.

MCM6 Inhibits Decidualization via Cross-Talking with ERK Pathway in Human Endometrial Stromal Cells

Decidualization plays an important role in the implantation of the embryo, but the molecular action implicated in this process is not completely known. Herein, we found that, compared with the proliferative endometrial tissues, the expression of minichromosome maintenance complex component 6 (MCM6) was markedly decreased in the secretory endometrial tissues. To verify the function of MCM6 in decidualization, in vitro decidualization model was constructed by treating human endometrial stromal cells (HESCs) with estrogen (E2) and progesterone (P4). Consistently, MCM6 level was downregulated in E2P4-treated HESCs. Administration of E2P4 accumulated HESCs in G1 cell cycle phase, leading to cell growth suppression. Ectopic expression of MCM6 promoted the transition of G1/S and restored the proliferation of HESCs that were inhibited by E2P4. MCM6 overexpression led to aberrant activation of extracellular signal-regulated kinase (ERK) and treatment with ERK agonist Ro 67-7476 restored MCM6 expression and cell proliferation inhibited by E2P4. Our data suggested that MCM6/ERK feedback loop plays a negative role in E2P4-induced decidualization and implies that MCM6 may be a promising target for meliorating uterine receptivity.

The Impacts of Inflammatory and Autoimmune Conditions on the Endometrium and Reproductive Outcomes

Background: A healthy pregnancy begins with an adequate endometrial state, even before the arrival of a blastocyst. Proper endometrial priming and the development of a tolerogenic decidua are key steps in creating the perfect environment for implantation and pregnancy. In these processes, the involvement of the maternal immune system seems to be of great relevance, modulating the different decidual immune populations to prepare the endometrium for a potential pregnancy. However, certain local pathologies of an inflammatory and autoimmune nature appear to have a direct impact on these phenomena, thus altering patients' reproductive outcomes. Methods: This literature review analyzes original articles, reviews, systematic reviews, and meta-analyses published between 1990 and 2024, concerning the impact of different inflammatory and autoimmune conditions on endometrial status and fertility. The included papers were obtained from Medline (Pubmed) and the Cochrane library. Results: There is evidence that endometriosis, adenomyosis, and chronic endometritis, through the promotion of a chronic inflammatory environment, are capable of altering endometrial immune populations, and, thus, processes essential for early pregnancy. Among other effects, these conditions have been linked to impaired decidualization, alterations in progesterone responsiveness, and hindered placentation. Similarly, antiphospholipid syndrome (APS), thyroid dysfunction, diabetes, and other pathologies related to glucose and gluten metabolism, due to their autoimmune nature, also appear to have a local impact on the uterine environment, affecting reproductive success through different mechanisms, including altered hormonal response and, again, impaired decidualization. Conclusions: The management of inflammatory and autoimmune diseases in assisted reproduction patients is gaining importance due to their direct impact on the endometrium. It is necessary to follow current expert recommendations and established therapeutic approaches in order to improve patients' prospects, ranging from antibiotic treatment in chronic endometritis to heparin and aspirin in APS, as well as hormonal treatments for endometriosis/adenomyosis or a gluten-free diet in celiac disease. All of them and the rest of the therapeutic perspectives, both current and under investigation, are presented throughout this work, assessing the possible improvements for reproductive outcomes.

Demystifying the landscape of endometrial immune microenvironment in luteal-phase from cuprotosis: Implications for the mechanism and treatment of RPL

BACKGROUND

Adaptive changes in the endometrial immune microenvironment during the luteal phase are essential for pregnancy, and their abnormalities are associated with recurrent pregnancy loss (RPL). Nevertheless, the specific mechanism is still unknown. Cuprotosis, an innovatively discovered type of programmed cell death, provides us with a pioneering perspective to decipher the landscape of luteal-phase endometrial immune microenvironment in RPL. This study aimed to analyze the immune landscape of luteal-phase endometrial microenvironment in RPL and explore the association of cuprotosis with it through integrative bioinformatics analysis.

METHODS

The microarrays involving the luteal phase endometrial tissue of RPL were obtained from the GEO database. Differentially expressed genes (DEGs) of RPL were screened and key modules were detected by WGCNA. GO, KEGG, and GSEA immune enrichment analyses were performed on the DEGs in the most relevant modules to RPL. Then, the endometrial immune microenvironment landscape of RPL was analyzed, including immune infiltration analysis and correlation analysis between immune cells or immune functions. The interaction of cuprotosis-related genes (CRGs), the expression level between groups, the immune localization and their correlation with immune cells and immune function were analyzed. LASSO regression and Nomogram evaluated the diagnostic value of immune-related CRGS in RPL. Functional enrichment analysis was performed on the RPL signature CRGs. And RPL samples were grouped according to the expression of 7 RPL signature CRGs through unsupervised clustering analysis. After that, we analyzed the expression level of CRGs and immune infiltration, as well as performed immune function enrichment analysis in subtypes. In addition, we also screened potential drugs that might act on CRGs to improve the pathological mechanism of RPL.

RESULTS

In this study, we uncovered that DEGs and genes in key modules derived from weighted gene co-expression network analysis (WGCNA) were involved in immune regulation. And the immune infiltration landscape of RPL was significantly different from healthy controls. Furthermore, six hub genes were screened from CRGs based on Cytohubba, and their expression profilings were verified in RPL and normal mouse samples. Besides, seven CRGs closely associated with the immune regulation of RPL were identified by Spearman correlation analysis, including SLC31A1, LIAS, DLD, DLAT, DBT, ATP7B, and ATP7A, named as immune-related CRGs. Furthermore, three subgroups clustered according to these seven genes showed significant differences in immune landscape, suggesting a remarkable effect of CRGs on immune regulation. Last but not least, we analyzed the regulation network of transcription factors, miRNAs, and CRGs, and screened potential compounds for the treatment of RPL by targeting CRGs.

CONCLUSIONS

The abnormal endometrial immune microenvironment in the luteal phase was associated with the pathomechanism of RPL, and cuprotosis was closely involved in the immune microenvironment in the luteal phase endometrium of RPL. Collectively, this study revealed the potential contribution of CRGs to the pathogenesis of RPL, providing a novel breakthroughs in insights into the pathogenesis, diagnosis, and treatment of RPL.

Differential gene expression in decidualized human endometrial stromal cells induced by different stimuli

Decidualization can be induced by culturing human endometrial stromal cells (ESCs) with several decidualization stimuli, such as cAMP, medroxyprogesterone acetate (MPA) or Estradiol (E2). However, it has been unclear how decidualized cells induced by different stimuli are different. We compared transcriptomes and cellular functions of decidualized ESCs induced by different stimuli (MPA, E2 + MPA, cAMP, and cAMP + MPA). We also investigated which decidualization stimulus induces a closer in vivo decidualization. Differentially expressed genes (DEGs) and altered cellular functions by each decidualization stimuli were identified by RNA-sequence and gene-ontology analysis. DEGs was about two times higher for stimuli that use cAMP (cAMP and cAMP + MPA) than for stimuli that did not use cAMP (MPA and E2 + MPA). cAMP-using stimuli altered the cellular functions including angiogenesis, inflammation, immune system, and embryo implantation whereas MPA-using stimuli (MPA, E2 + MPA, and cAMP + MPA) altered the cellular functions associated with insulin signaling. A public single-cell RNA-sequence data of the human endometrium was utilized to analyze in vivo decidualization. The altered cellular functions by in vivo decidualization were close to those observed by cAMP + MPA-induced decidualization. In conclusion, decidualized cells induced by different stimuli have different transcriptome and cellular functions. cAMP + MPA may induce a decidualization most closely to in vivo decidualization.

Establishment of Murine Pregnancy Requires the Promyelocytic Leukemia Zinc Finger Transcription Factor

Using an established human primary cell culture model, we previously demonstrated that the promyelocytic leukemia zinc finger (PLZF) transcription factor is a direct target of the progesterone receptor (PGR) and is essential for progestin-dependent decidualization of human endometrial stromal cells (HESCs). These in vitro findings were supported by immunohistochemical analysis of human endometrial tissue biopsies, which showed that the strongest immunoreactivity for endometrial PLZF is detected during the progesterone (P4)-dominant secretory phase of the menstrual cycle. While these human studies provided critical clinical support for the important role of PLZF in P4-dependent HESC decidualization, functional validation in vivo was not possible due to the absence of suitable animal models. To address this deficiency, we recently generated a conditional knockout mouse model in which PLZF is ablated in PGR-positive cells of the mouse (Plzf d/d). The Plzf d/d female was phenotypically analyzed using immunoblotting, real-time PCR, and immunohistochemistry. Reproductive function was tested using the timed natural pregnancy model as well as the artificial decidual response assay. Even though ovarian activity is not affected, female Plzf d/d mice exhibit an infertility phenotype due to an inability of the embryo to implant into the Plzf d/d endometrium. Initial cellular and molecular phenotyping investigations reveal that the Plzf d/d endometrium is unable to develop a transient receptive state, which is reflected at the molecular level by a blunted response to P4 exposure with a concomitant unopposed response to 17-β estradiol. In addition to a defect in P4-dependent receptivity, the Plzf d/d endometrium fails to undergo decidualization in response to an artificial decidual stimulus, providing the in vivo validation for our earlier HESC culture findings. Collectively, our new Plzf d/d mouse model underscores the physiological importance of the PLZF transcription factor not only in endometrial stromal cell decidualization but also uterine receptivity, two uterine cellular processes that are indispensable for the establishment of pregnancy.

A Potential Role of CD82/KAI1 during Uterine Decidualization in Mice

The tumor metastasis suppressor gene CD82/KAI1 has been demonstrated to impact human trophoblast invasion and migration. Communication between trophoblasts and decidual stromal cells plays a crucial role in controlling the normal invasiveness of trophoblasts. However, whether CD82/KAI1 is involved in decidualization and what role it plays remain unclear. CD82/KAI1 demonstrates specific spatiotemporal expression patterns in stromal cells undergoing decidualization during pregnancy. This is observed in both naturally pregnant females post-implantation and pseudopregnant mice undergoing induced decidualization, as detected through in situ hybridization and immunofluorescence. CD82/KAI1 expression showed a significant time-dependent increase in cultured stromal cells after 24 and 48 h of progesterone (P4) and estrogen (E2) treatment. This was accompanied by a notable upregulation of decidualization markers, including cyclin D3 and PR. After transducing stromal cells with the adenovirus-overexpressing CD82/KAI1 for 48 h, the expression of cyclin D3 protein increased. Meanwhile, there was an attenuated expression of CD82/KAI1 due to an adenovirus siRNA knockdown, whereas cyclin D3 and PR expressions were not affected. Our findings suggest a potential role of CD82/KAI1 in regulating the process of decidualization, providing insights into stromal cell differentiation.

Antibiotic cured chronic endometritis remains a risk factor for early pregnancy loss in the subsequent frozen euploid embryo transfer

RESEARCH QUESTION

Do patients with antibiotic-cured chronic endometritis (CCE) have a comparable pregnancy outcome to those with non-chronic endometritis (NCE) in the subsequent frozen embryo transfer (FET) cycle?

DESIGN

A retrospective cohort analysis included 833 patients in their first FET cycles with single euploid embryo transfer. Chronic endometritis (≥5 CD138+ plasma cells per high-power field [CD138+/HPF]) was treated with standard antibiotic therapy. Patients were classified into two groups: the NCE group (n = 611, <5 CD138+/HPF) and the CCE group (n = 222, ≥5 CD138+/HPF and cured after antibiotic treatment). Pregnancy outcomes were compared. NCE group was divided into subgroup 1 (CD138+/HPF = 0) and subgroup 2 (CD138+/HPF = 1-4) for further analysis.

RESULTS

The rate of early pregnancy loss (EPL), incorporating all losses before 10 weeks' gestation, was significantly higher in the CCE group than the NCE group (21.2% versus 14.2%, P = 0.016), and the difference was statistically significant (adjusted odds ratio [AOR] 1.68, 95% confidence interval [CI] 1.11-2.55). No significant differences were observed between the two groups with regard to other pregnancy outcomes. In the subgroup analysis, the EPL rate and biochemical pregnancy rate were significantly higher in subgroup 2 than subgroup 1 (17.2% versus 9.4%, AOR 2.21, 95% CI 1.30-3.74; 12.2% versus 6.9%, AOR 2.01, 95% CI 1.09-3.68).

CONCLUSIONS

Chronic endometritis cured by standard antibiotic therapy remains a risk factor for EPL in FET cycles, although no differences were found in live birth rates between patients with CCE or with NCE.

USP7 promotes decidualization of ESCs by STAT3/PR axis during early pregnancy

Decidualization is an essential process for embryo implantation during early pregnancy. Defective decidualization is a critical leading cause of early pregnancy loss (EPL). Ubiquitin-specific protease 7 (USP7) is a deubiquitinating enzyme that is involved in uterine function. This study aimed to explore the underlying mechanism by which USP7 regulates decidualization in EPL. We found that USP7 was downregulated in the decidual tissue of EPL patients. Upregulation of USP7 enhanced decidualization in endometrial stromal cells (ESCs), with increased decidualized biomarkers IGFBP1 and PRL and progesterone receptor A/B (PR-A/B) expression. Moreover, we found that signal transducer and activator of transcription 3 (STAT3) is a direct target of USP7 in ESCs. USP7 bound to STAT3 by deubiquitination and increased STAT3 levels in ESCs. Suppression of STAT3 impeded the USP7-promoted cell viability, decidualization, and PR-A/B expression of ESCs. USP7 promoted the decidualization of ESCs through the STAT3/PR signaling pathway during early pregnancy, which provides new insight into the pathological mechanism of EPL and may contribute to the clinical treatment of EPL.

High incidence of decidualization failure in infertile women

Purpose

Decidualization is an important event for embryo implantation and successful pregnancy. Impaired decidualization leads to implantation failure and miscarriage. However, it is unclear how often decidualization failure occurs in infertile women. By analyzing the endometrium at late-secretory phase, we investigated the incidence and pathogenesis of decidualization failure among infertile women.

Methods

Endometrial dating was performed on the endometria obtained in the late-secretory phase from 33 infertile women. Endometrial dating of more than 2 days delay was taken as an indication of decidualization failure. The expression of essential transcription factors for decidualization (FOXO1, WT1, and C/EBPβ) was examined by immunohistochemistry.

Results

Among 32 cases, 20 cases (62.5%) showed decidualization failure. These patients tended to have a history of more frequent miscarriages than those without decidualization failure. The percentage of cells that immunostained positive for the expression of three transcription factors was significantly lower in the patients with decidualization failure than in those without decidualization failure. Serum progesterone levels measured in the mid- and late-secretory phase were not significantly different between the cases with and without decidualization failure.

Conclusions

The incidence of decidualization failure is high in infertile women.

Exploring the sophistications of unexplained recurrent pregnancy loss: A case-control study

BACKGROUND

Unexplained recurrent pregnancy loss (URPL) is a significant obstetric challenge affecting maternal health and well-being. Genetic factors, including mutations in the methylenetetrahydrofolate reductase (MTHFR) gene and elevated homocysteine levels, are increasingly recognized as contributors to URPL, though their precise roles remain complex. This study aimed to comprehensively explore these factors.

OBJECTIVES

This study examines the links between MTHFR gene polymorphisms (C677T and A1298C), plasma homocysteine levels, and URPL. It also aims to create a predictive model for URPL based on these factors.

DESIGN

A case-control study with Vietnamese women who had at least one pregnancy between January 2017 and June 2020, recruited from Medlatec Hospital and Hanoi Medical University. Participants included URPL cases (n = 128) and controls (n = 126).

METHODS

Participants were selected based on specific criteria. Main analyses identified the optimal multivariable logistic regression model for predicting URPL using Bayesian Model Averaging, with the optimal model chosen based on the highest Area Under the Curve (AUC) and posterior probability. A nomogram for clinical risk prediction was developed based on parameters from the optimal model.

RESULTS

URPL cases exhibited significantly higher plasma homocysteine levels (11.73 ± 6.08 µmol/L) compared to controls (7.64 ± 1.78 µmol/L), correlating with increased URPL risk (OR: 1.64, 95% confidence interval (CI): 1.41-1.96; p < 0.001). The MTHFR C677T variant showed strong associations with URPL, particularly the CT genotype (OR: 6.07, 95% CI: 3.00-12.93; p < 0.001) and TT genotype (OR: 14.62, 95% CI: 2.85-114.77; p = 0.003). Similarly, the A1298C variant demonstrated elevated URPL risk with the AC genotype (OR: 2.73, 95% CI: 1.34-5.78; p = 0.007) and CC genotype (OR: 12.43, 95% CI: 3.17-64.22; p = 0.001).

CONCLUSION

This study provides insights into the complex interplay of MTHFR gene mutations, elevated homocysteine levels, and URPL. Genetic testing and biomarker assessment may play a crucial role in customizing risk assessment and management strategies for women at risk of URPL.

The Pathological Role of miRNAs in Endometriosis

Association studies investigating miRNA in relation to diseases have consistently shown significant alterations in miRNA expression, particularly within inflammatory pathways, where they regulate inflammatory cytokines, transcription factors (such as NF-κB, STAT3, HIF1α), and inflammatory proteins (including COX-2 and iNOS). Given that endometriosis (EMS) is characterized as an inflammatory disease, albeit one influenced by estrogen levels, it is natural to speculate about the connection between EMS and miRNA. Recent research has indeed confirmed alterations in the expression levels of numerous microRNAs (miRNAs) in both endometriotic lesions and the eutopic endometrium of women with EMS, when compared to healthy controls. The undeniable association of miRNAs with EMS hints at the emergence of a new era in the study of miRNA in the context of EMS. This article reviews the advancements made in understanding the pathological role of miRNA in EMS and its association with EMS-associated infertility. These findings contribute to the ongoing pursuit of developing miRNA-based therapeutics and diagnostic markers for EMS.

Before Is Better: Innovative Multidisciplinary Preconception Care in Different Clinical Contexts

CONTEXT

Implementation of pre-conception care units is still very limited in Italy. Nowadays, the population's awareness of the reproductive risks that can be reduced or prevented is very low. Purpose and main findings: We presented a new personalized multidisciplinary model of preconception care aimed at identifying and possibly reducing adverse reproductive events. We analyzed three cohorts of population: couples from the general population, infertile or subfertile couples, and couples with a previous history of adverse reproductive events. The proposal involves a deep investigation regarding family history, the personal histories of both partners, and reproductive history.

PRINCIPAL CONCLUSIONS

Preconception care is still neglected in Italy and under-evaluated by clinicians involved in natural or in vitro reproduction. Adequate preconception counseling will improve maternal and fetal obstetrical outcomes.

Exploring the presence of markers of decidualization in the fallopian tubes: a systematic review

The fallopian tubes (FTs) are part of the female upper genital tract. The healthy FT provides the biological environment for successful fertilization and facilitates the subsequent movement of the conceptus to the endometrial cavity. However, when the FT is damaged, as with salpingitis, pyosalpinx, and hydrosalpinx, it may increase the risk of an ectopic pregnancy, a life-threatening condition. Decidualization refers to a multifactorial process by which the endometrium changes to permit blastocyst implantation. The decidualization reaction is vital for endometrial receptivity during the window of implantation. To date, no comprehensive review that collates evidence on decidualization in the human FT has been conducted. Therefore, the aim of this review is to compile the current evidence on cellular decidualization occurring in the healthy and pathological FT in women of reproductive age. A literature search was conducted using five databases and identified 746 articles, 24 of which were analyzed based on inclusion and exclusion criteria. The available evidence indicates that the FT are able to undergo decidual changes under specific circumstances; however, the exact mechanism by which this occurs is poorly understood. Further research is needed to elucidate the mechanism by which decidualization can occur in the FT.

Endometrial and placental stem cells in successful and pathological pregnancies

The endometrium is a dynamic tissue that undergoes extensive remodeling during the menstrual cycle and further gets modified during pregnancy. Different kinds of stem cells are reported in the endometrium. These include epithelial stem cells, endometrial mesenchymal stem cells, side population stem cells, and very small embryonic-like stem cells. Stem cells are also reported in the placenta which includes trophoblast stem cells, side population trophoblast stem cells, and placental mesenchymal stem cells. The endometrial and placental stem cells play a pivotal role in endometrial remodeling and placental vasculogenesis during pregnancy. The dysregulation of stem cell function is reported in various pregnancy complications like preeclampsia, fetal growth restriction, and preterm birth. However, the mechanisms by which it does so are yet elusive. Herein, we review the current knowledge of the different type of stem cells involved in pregnancy initiation and also highlight how their improper functionality leads to pathological pregnancy.

Silicon dioxide nanoparticles compromise decidualization via autophagy impairment to possibly cause embryo resorption

The wide application of silicon dioxide nanoparticles (SiO₂NPs) has raised concerns about their harmful effects on reproduction. The purpose of this research was to investigate the toxic effects and the possible mechanisms by which SiO₂NPs affect decidualization and pregnancy progression. We found that SiO₂NPs could inhibit decidualization, both in mice and in human endometrial stromal cells (HESCs). Embryo resorption was also evident in mice treated with SiO₂NPs. When HESCs were treated with SiO₂NPs, decidualization was inhibited and there was an increase in intracellular lysosomes and autophagosomes as well as the blockage of autophagic flux. Interestingly, a reduction of autophagosome accumulation via 3-methyladenine (3MA) significantly restored the decidualization of HESCs. In summary, our results indicate that SiO₂NPs can affect embryo survival by impairing decidualization through a dysfunctional autophagic process.

E2F2 is upregulated by the ERK pathway and regulates decidualization via MCM4

Cell cycle modulation is an important event during decidualization. E2F2 is a transcription regulator that plays a vital role in cell cycle regulation. However, the biological role of E2F2 in decidualization has not yet been identified. In this study, estrogen (E2) and progestin (P4)-induced in vitro and in vivo decidualization models were applied. Our data showed that the expression levels of E2F2 and its downstream target MCM4 were downregulated in the uterus tissues of E2P4-treated mice compared with control mice. In hESCs, exposure to E2P4 resulted in a significant decrease in E2F2 and MCM4 expression. E2P4 treatment reduced hESC proliferation and ectopic expression of E2F2 or MCM4 elevated the viability of E2P4-treated hESCs. In addition, ectopic expression of E2F2 or MCM4 restored the expression of G1 phase-associated proteins. The ERK pathway was inactivated in E2P4-treated hESCs. Treatment with ERK agonist Ro 67-7476 restored the expression of E2F2, MCM4, and G1 phase-associated proteins that were inhibited by E2P4. Moreover, Ro 67-7476 retracted the levels of IGFBP1 and PRL that were induced by E2P4. Collectively, our results indicate that E2F2 is regulated by ERK signaling and contributes to decidualization via regulation of MCM4. Therefore, E2F2/MCM4 cascade may serve as promising targets for alleviating decidualization dysfunction.

Endometrial Microbiota and Immune Tolerance in Pregnancy

Recent studies have demonstrated that the uterus has its own microbiota. However, there is no consensus on endometrial microbiota composition, thus its role in the healthy uterine environment is still a frontier topic. Endometrial receptivity is key to embryo implantation, and in this specific context immunological tolerance against fetal antigens and the tightly regulated expression of inflammatory mediators are fundamental. According to recent evidence, endometrial microbiota may interact in a very dynamic way with the immune system during the peri-conceptional stage and later during pregnancy. For this reason, a condition of dysbiosis might lead to adverse pregnancy outcomes. The aim of this review is to summarize the evidence on the molecular mechanisms by which the endometrial microbiota may interact with the immune system. For this purpose, the link between dysbiosis and reproductive disorders, such as infertility, recurrent pregnancy loss (RPL), and preterm birth, will be discussed. In conclusion, the most recent findings from molecular analyses will be reported to illustrate and possibly overcome the intrinsic limitations of uterine microbiota detection (low endometrial biomass, high risk of contamination during sampling, and lack of standardization).

Antinuclear antibodies positivity in women in reproductive age: From infertility to adverse obstetrical outcomes - A meta-analysis

This systematic review and meta-analysis were designed to identify possible correlations between isolated serum antinuclear antibody (ANA) and (i) infertility in the context of in-vitro fertilization (IVF), (ii) idiopathic recurrent pregnancy losses (RPL), and (iii) second/ third trimester pregnancy complications. We performed a systematic review and meta-analysis of the literature in PubMed Library database from inception to March 2022 following PRISMA guidelines. Our pooled results showed a lower pregnancy rate among ANA-positive women undergoing IVF/ICSI compared to ANA-negative women undergoing the same procedures (279/908 versus 1136/2347, random effect, odds ratio -OR- 0.50, 95% confidence interval -CI- 0.38-0.67, p 0.00001, I² = 58%). We also reported a higher miscarriage rate among ANA-positive compared to ANA-negative women (48/223 versus 109/999, random effect, OR: 3.25 95% CI: 1.57-6.76, p = 0.002, I² = 61%) and a lower implantation rate (320/1489 versus 1437/4205, random effect, OR: 0.51, 95% CI: 0.36-0.72, p = 0.0001, I² = 78%). Regarding RPL, pooled results demonstrated a higher prevalence of ANA-positivity in RPL women compared to controls (698/2947 versus 240/3145, random effect, OR: 3.22, 95% CI: 2.12-4.88, p 0.00001, I² 77%), either using > 2 or > 3 pregnancy losses threshold for defining RPL. Heterogeneity of reporting outcome did not allow a quantitative analysis and led to no clear demonstration of an effect of serum ANA on the incidence of stillbirth, preeclampsia and hypertensive disorders. In conclusion, the unfavorable effect of serum ANA was observed in women following IVF. Similarly, ANA were associated with the risk of RPL, while data were unconclusive in terms of late pregnancy complications.

When Less Is More – Pipelle Endometrial Sampling for Quantification of Uterine Natural Killer Cells in Patients With Recurrent Implantation Failure or Habitual Abortion

Despite recent advancements in reproductive medicine, recurrent implantation failure and habitual abortion remain ongoing issues. One of the most important aspects of successful implantation is the intricate immune response and regulation necessary for the acceptance of the hemiallogenic embryo. The most numerous immune cells in the decidua are uterine natural killer cells (uNK). Studies suggest that changes in the uNK count and physiology may be responsible for the aforementioned pathological conditions. Thus, testing for uNK may provide valuable insights into their pathogenesis. The study compared Pipelle endometrial sampling with conventional curettage to find out whether the less invasive Pipelle method is a viable alternative of tissue collection. Tissue samples from 14 patients obtained by both methods were examined. The average size of tissue samples obtained with Pipelle was 17 mm2, samples obtained with curettage had on average 34 mm2. Using immunohistochemical visualization of CD56 (NK cells) and granzyme B antigens (serine protease-expressing activation state of NK cells), it was found that the average total count of CD56 / mm2 was 115 for Pipelle and 120 for curettage, respectively. The study also proved a correlation between granzyme B positivity and identification of NK cells clusters. The results indicated that Pipelle endometrial sampling seems a suitable method of tissue harvesting for the purpose of uNK cells examination. Pipelle endometrial sampling is safe, cost-effective and can be performed on an outpatient basis without the need of anesthesia or analgesia. Several issues remain yet to be solved: how to standardize the subsequent uNK testing, how to interpret the results and finally yet importantly, how to use this knowledge in personalized treatment protocols.

Alleviation of Severe Skin Insults Following High-Dose Irradiation with Isolated Human Fetal Placental Stromal Cells

Skin exposure to high-dose irradiation, as commonly practiced in radiotherapy, affects the different skin layers, causing dry and wet desquamation, hyperkeratosis fibrosis, hard to heal wounds and alopecia and damaged hair follicles. Fetal tissue mesenchymal stromal cells (f-hPSC) were isolated from excised human fetal placental tissue, based on their direct migration from the tissue samples to the tissue dish. The current study follows earlier reports on for the mitigation of acute radiation syndrome following whole body high-dose exposure with remotely injected f-hPSC. Both the head only and a back skin flap of mice were irradiated with 16 &18 Gy, respectively, by 6MeV clinical linear accelerator electron beam. In both locations, the irradiated skin areas developed early and late radiation induced skin damages, including cutaneous fibrosis, lesions, scaring and severe hair follicle loss and reduced hair pigmentation. Injection of 2 × 106 f-hPSC, 3 and 8 weeks following 16 Gy head irradiation, and 1 and 4 weeks following the 18 Gy back skin only irradiation, resulted in significantly faster healing of radiation induced damages, with reduction of wet desquamation as measured by surface moisture level and minor recovery of the skin viscoelasticity. Detailed histological morphometry showed a clear alleviation of radiation induced hyperkeratosis in f-hPSC treated mice, with significant regain of hair follicles density. Following 16 Gy head irradiation, the hair follicles density in the scalp skin was reduced significantly by almost a half relative to the controls. A nearly full recovery of hair density was found in the f-hPSC treated mice. In the 18 Gy irradiated back skin, the hair follicles density dropped in a late stage by ~70% relative to naïve controls. In irradiated f-hPSC treated mice, it was reduced by only ~30% and was significantly higher than the non-treated group. Our results suggest that local injections of xenogeneic f-hPSC could serve as a simple, safe and highly effective non-autologous pro-regenerative treatment for high-dose radiation induced skin insults. We expect that such treatment could also be applied for other irradiated organs.

Implantation Failure in Endometriosis Patients: Etiopathogenesis

Embryo implantation requires adequate dialogue between a good quality embryo and a receptive endometrium. This implantation is still considered as the black box of reproductive medicine. Endometriosis is a highly prevalent chronic inflammatory disease, concerning about 10% of women of reproductive age and is one of the major causes of female infertility. The mechanisms involved in endometriosis-related infertility, an event not yet completely understood, are multifactorial and include anatomical changes, reduction in ovarian reserve, endocrine abnormalities, genetic profile, immunity markers, inflammatory mediators, or altered endometrial receptivity. In this article, we will focus on the impact of endometriosis on embryo quality and on endometrial receptivity. Results: Poor oocyte and embryo quality seem to promote a lower pregnancy rate, more than the endometrium itself in women with endometriosis. Other studies report the contrary. In addition, hormonal imbalance observed in the endometrium could also alter the embryo implantation. Conclusions: Controversial results in the literature add difficulties to the understanding of the mechanisms that lead to embryo implantation disorders. Furthermore, either oocyte/embryo impairment, altered endometrium, or both may cause impaired implantation. New prospective, randomized, and controlled studies are necessary to determine the origin of the defects that make conception more difficult in the case of endometriosis and adenomyosis.

Endometrial Epithelial ARID1A Is Required for Uterine Immune Homeostasis during Early Pregnancy

A growing body of work suggests epigenetic dysregulation contributes to endometriosis pathophysiology and female infertility. The chromatin remodeling complex subunit AT-rich interaction domain 1A (ARID1A) must be properly expressed to maintain normal uterine function. Endometrial epithelial ARID1A is indispensable for pregnancy establishment in mice through regulation of endometrial gland function; however, ARID1A expression is decreased in infertile women with endometriosis. We hypothesized that ARID1A performs critical operations in the endometrial epithelium necessary for fertility besides maintaining gland function. To identify alterations in uterine gene expression resulting from loss of epithelial ARID1A, we performed RNA-sequencing analysis on pre-implantation uteri from LtfiCre/+Arid1af/f and control mice. Differential expression analysis identified 4181 differentially expressed genes enriched for immune-related ingenuity canonical pathways including agranulocyte adhesion and diapedesis and natural killer cell signaling. RT-qPCR confirmed an increase in pro-inflammatory cytokine and macrophage-related gene expression but a decrease in natural killer cell signaling. Immunostaining confirmed a uterus-specific increase in macrophage infiltration. Flow cytometry delineated an increase in inflammatory macrophages and a decrease in uterine dendritic cells in LtfiCre/+Arid1af/f uteri. These findings demonstrate a role for endometrial epithelial ARID1A in suppressing inflammation and maintaining uterine immune homeostasis, which are required for successful pregnancy and gynecological health.

(Dis)similarities between the Decidual and Tumor Microenvironment

Placenta-specific trophoblast and tumor cells exhibit many common characteristics. Trophoblast cells invade maternal tissues while being tolerated by the maternal immune system. Similarly, tumor cells can invade surrounding tissues and escape the immune system. Importantly, both trophoblast and tumor cells are supported by an abetting microenvironment, which influences invasion, angiogenesis, and immune tolerance/evasion, among others. However, in contrast to tumor cells, the metabolic, proliferative, migrative, and invasive states of trophoblast cells are under tight regulatory control. In this review, we provide an overview of similarities and dissimilarities in regulatory processes that drive trophoblast and tumor cell fate, particularly focusing on the role of the abetting microenvironments.

Fetal inflammatory response at the fetomaternal interface: A requirement for labor at term and preterm

Human parturition at term and preterm is an inflammatory process synchronously executed by both fetomaternal tissues to transition them from a quiescent state t an active state of labor to ensure delivery. The initiators of the inflammatory signaling mechanism can be both maternal and fetal. The placental (fetal)-maternal immune and endocrine mediated homeostatic imbalances and inflammation are well reported. However, the fetal inflammatory response (FIR) theories initiated by the fetal membranes (amniochorion) at the choriodecidual interface are not well established. Although immune cell migration, activation, and production of proparturition cytokines to the fetal membranes are reported, cellular level events that can generate a unique set of inflammation are not well discussed. This review discusses derangements to fetal membrane cells (physiologically and pathologically at term and preterm, respectively) in response to both endogenous and exogenous factors to generate inflammatory signals. In addition, the mechanisms of inflammatory signal propagation (fetal signaling of parturition) and how these signals cause immune imbalances at the choriodecidual interface are discussed. In addition to maternal inflammation, this review projects FIR as an additional mediator of inflammatory overload required to promote parturition.