Decreased AMPK/SIRT1/PDK4 induced by androgen excess inhibits human endometrial stromal cell decidualization in PCOS.

Polycystic ovary syndrome (PCOS) is a complex common endocrine disorder affecting women of reproductive age. Ovulatory dysfunction is recognized as a primary infertile factor, however, even when ovulation is medically induced and restored, PCOS patients continue to experience reduced cumulative pregnancy rates and a higher spontaneous miscarriage rate. Hyperandrogenism, a hallmark feature of PCOS, affects ovarian folliculogenesis, endometrial receptivity, and the establishment and maintenance of pregnancy. Decidualization denotes the transformation that the stromal compart of the endometrium must undergo to accommodate pregnancy, driven by the rising progesterone levels and local cAMP production. However, studies on the impact of hyperandrogenism on decidualization are limited. In this study, we observed that primary endometrial stromal cells from women with PCOS exhibit abnormal responses to progesterone during in vitro decidualization. A high concentration of testosterone inhibits human endometrial stromal cells (HESCs) decidualization. RNA-Seq analysis demonstrated that pyruvate dehydrogenase kinase 4 (PDK4) expression was significantly lower in the endometrium of PCOS patients with hyperandrogenism compared to those without hyperandrogenism. We also characterized that the expression of PDK4 is elevated in the endometrium stroma at the mid-secretory phase. Artificial decidualization could enhance PDK4 expression, while downregulation of PDK4 leads to abnormal decidualization both in vivo and in vitro. Mechanistically, testosterone excess inhibits IGFBP1 and PRL expression, followed by phosphorylating of AMPK that stimulates PDK4 expression. Based on co-immunoprecipitation analysis, we observed an interaction between SIRT1 and PDK4, promoting glycolysis to facilitate decidualization. Restrain of AR activation resumes the AMPK/SIRT1/PDK4 pathway suppressed by testosterone excess, indicating that testosterone primarily acts on decidualization through AR stimulation. Androgen excess in the endometrium inhibits decidualization by disrupting the AMPK/SIRT1/PDK4 signaling pathway. These data demonstrate the critical roles of endometrial PDK4 in regulating decidualization and provide valuable information for understanding the underlying mechanism during decidualization.

Connecting the dots: the role of fatigue in female infertility.

Fatigue, an increasingly acknowledged symptom in various chronic diseases, has garnered heightened attention, during the medical era of bio-psycho-social model. Its persistence not only significantly compromises an individual's quality of life but also correlates with chronic organ damage. Surprisingly, the intricate relationship between fatigue and female reproductive health, specifically infertility, remains largely unexplored. Our exploration into the existing body of evidence establishes a compelling link between fatigue with uterine and ovarian diseases, as well as conditions associated with infertility, such as rheumatism. This observation suggests a potentially pivotal role of fatigue in influencing overall female fertility. Furthermore, we propose a hypothetical mechanism elucidating the impact of fatigue on infertility from multiple perspectives, postulating that neuroendocrine, neurotransmitter, inflammatory immune, and mitochondrial dysfunction resulting from fatigue and its co-factors may further contribute to endocrine disorders, menstrual irregularities, and sexual dysfunction, ultimately leading to infertility. In addition to providing this comprehensive theoretical framework, we summarize anti-fatigue strategies and accentuate current knowledge gaps. By doing so, our aim is to offer novel insights, stimulate further research, and advance our understanding of the crucial interplay between fatigue and female reproductive health.

Hyperandrogenic environment regulates the function of ovarian granulosa cells by modulating macrophage polarization in PCOS.

BACKGROUND: Polycystic ovary syndrome (PCOS) is a common endocrine-metabolic disorder characterized by oligo-anovulation, hyperandrogenism, and polycystic ovaries, with hyperandrogenism being the most prominent feature of PCOS patients. However, whether excessive androgens also exist in the ovarian microenvironment of patients with PCOS, and their modulatory role on ovarian immune homeostasis and ovarian function, is not clear. METHODS: Follicular fluid samples from patients participating in their first in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment were collected. Androgen concentration of follicular fluid was assayed by chemiluminescence, and the macrophage M1:M2 ratio was detected by flow cytometry. In an in vitro model, we examined the regulatory effects of different concentrations of androgen on macrophage differentiation and glucose metabolism levels using qRT-PCR, Simple Western and multi-factor flow cytometry assay. In a co-culture model, we assessed the effect of a hyperandrogenic environment in the presence or absence of macrophages on the function of granulosa cells using qRT-PCR, Simple Western, EdU assay, cell cycle assay, and multi-factor flow cytometry assay. RESULTS: The results showed that a significantly higher androgen level and M1:M2 ratio in the follicular fluid of PCOS patients with hyperandrogenism. The hyperandrogenic environment promoted the expression of pro-inflammatory and glycolysis-related molecules and inhibited the expression of anti-inflammatory and oxidative phosphorylation-related molecules in macrophages. In the presence of macrophages, a hyperandrogenic environment significantly downregulated the function of granulosa cells. CONCLUSION: There is a hyperandrogenic microenvironment in the ovary of PCOS patients with hyperandrogenism. Hyperandrogenic microenvironment can promote the activation of ovarian macrophages to M1, which may be associated with the reprogramming of macrophage glucose metabolism. The increased secretion of pro-inflammatory cytokines by macrophages in the hyperandrogenic microenvironment would impair the normal function of granulosa cells and interfere with normal ovarian follicle growth and development.

The role of extracellular vesicles from placenta and endometrium in pregnancy: Insights from tumor biology.

Extracellular vesicles (EVs) are small membrane-bound particles secreted by various cell types that play a critical role in intercellular communication by packaging and delivering biomolecules. In recent years, EVs have emerged as essential messengers in mediating physiological and pathological processes in tumor biology. The tumor microenvironment (TME) plays a pivotal role in tumor generation, progression, and metastasis. In this review, we provide an overview of the impact of tumor-derived EVs on both tumor cells and the TME. Moreover, we draw parallels between tumor biology and pregnancy, as successful embryo implantation also requires intricate intercellular communication between the placental trophecepiblast and the endometrial epithelium. Additionally, we discuss the involvement of EVs in targeting immune responses, trophoblast invasion, migration, and angiogenesis, which are shared biological processes between tumors and pregnancy. Specifically, we highlight the effects of placenta-derived EVs on the fetal-maternal interface, placenta, endometrium, and maternal system, as well as the role of endometrium-derived EVs in embryo-endometrial communication. However, challenges still exist in EVs research, including the standardization of EVs isolation methods for diagnostic testing, which also apply to reproductive systems where EVs-mediated communication is proposed to take place. Through this review, we aim to deepen the understanding of EVs, particularly in the context of reproductive biology, and encourage further investigation in this field.

CD317+ MSCs expanded with chemically defined media have enhanced immunological anti-inflammatory activities.

BACKGROUND: Although both preclinical and clinical studies have shown the great application potential of MSCs (mesenchymal stem/stromal cells) in treating many kinds of diseases, therapeutic inconsistency resulting from cell heterogeneity is the major stumbling block to their clinical applications. Cell population diversity and batch variation in the cell expansion medium are two major inducers of MSC heterogeneity. METHODS: Cell population diversity was investigated through single-cell RNA sequencing analysis of human MSCs derived from the umbilical cord and expanded with fully chemically defined medium in the current study. Then, the MSC subpopulation with enhanced anti-inflammatory effects was studied in vitro and in vivo. RESULTS: Our data showed that MSCs contain different populations with different functions, including subpopulations with enhanced functions of exosome secretion, extracellular matrix modification and responses to stimuli (regeneration and immune response). Among them, CD317+ MSCs have improved differentiation capabilities and enhanced immune suppression activities. Underlying mechanism studies showed that higher levels of TSG6 confer enhanced anti-inflammatory functions of CD317+ MSCs. CONCLUSIONS: Thus, CD317+ MSCs might be a promising candidate for treating immunological disorder-related diseases.

Trophoblast-derived miR-410-5p induces M2 macrophage polarization and mediates immunotolerance at the fetal-maternal interface by targeting the STAT1 signaling pathway.

BACKGROUND: Macrophages phenotypic deviation and immune imbalance play vital roles in pregnancy-associated diseases such as spontaneous miscarriage. Trophoblasts regulate phenotypic changes in macrophages, however, their underlying mechanism during pregnancy remains unclear. Therefore, this study aimed to elucidate the potential function of trophoblast-derived miRNAs (miR-410-5p) in macrophage polarization during pregnancy. METHODS: Patient decidual macrophage tissue samples in spontaneous abortion group and normal pregnancy group (those who had induced abortion for non-medical reasons) were collected at the Reproductive Medicine Center of Renmin Hospital of Wuhan University from April to December 2021. Furthermore, placental villi and decidua tissue samples were collected from patients who had experienced a spontaneous miscarriage and normal pregnant women for validation and subsequent experiments at the Shenzhen Zhongshan Obstetrics & Gynecology Hospital (formerly Shenzhen Zhongshan Urology Hospital), from March 2021 to September 2022. As an animal model, 36 female mice were randomly divided into six groups as follows: naive-control, lipopolysaccharide-model, agomir-negative control prevention, agomir-410-5p prevention, agomir-negative control treatment, and agomir-410-5p treatment groups. We analyzed the miR-410-5p expression in abortion tissue and plasma samples; and supplemented miR-410-5p to evaluate embryonic absorption in vivo. The main source of miR-410-5p at the maternal-fetal interface was analyzed, and the possible target gene, signal transducer and activator of transcription (STAT) 1, of miR-410-5p was predicted. The effect of miR-410-5p and STAT1 regulation on macrophage phenotype, oxidative metabolism, and mitochondrial membrane potential was analyzed in vitro. RESULTS: MiR-410-5p levels were lower in the spontaneous abortion group compared with the normal pregnancy group, and plasma miR-410-5p levels could predict pregnancy and spontaneous abortion. Prophylactic supplementation of miR-410-5p in pregnant mice reduced lipopolysaccharide-mediated embryonic absorption and downregulated the decidual macrophage pro-inflammatory phenotype. MiR-410-5p were mainly distributed in villi, and trophoblasts secreted exosomes-miR-410-5p at the maternal-fetal interface. After macrophages captured exosomes, the cells shifted to the tolerance phenotype. STAT1 was a potential target gene of miR-410-5p. MiR-410-5p bound to STAT1 mRNA, and inhibited the expression of STAT1 protein. STAT1 can drive macrophages to mature to a pro-inflammatory phenotype. MiR-410-5p competitive silencing of STAT1 can avoid macrophage immune disorders. CONCLUSION: MiR-410-5p promotes M2 macrophage polarization by inhibiting STAT1, thus ensuring a healthy pregnancy. These findings are of great significance for diagnosing and preventing spontaneous miscarriage, providing a new perspective for further research in this field.

Intrauterine perfusion of dexamethasone improves pregnancy outcomes in recurrent reproductive failure patients with elevated uterine natural killer cells. A retrospective cohort study.

OBJECTIVE: To determine the effect of intrauterine perfusion of dexamethasone (DXM) on pregnancy outcomes in recurrent reproductive failure (RRF) patients with elevated uNK cells. METHODS: This retrospective cohort study included 132 RRF patients with elevated uNK cells: 56 patients received DXM treatment and 76 patients refused it in the frozen-thawed embryo transfer cycles. To determine the efficacy of intrauterine perfusion of DXM, multivariate logistic regression models and diagnosis-based subgroup analysis were performed. We also compared the pregnancy outcomes of patients with different responsiveness to DXM treatment. RESULTS: Intrauterine perfusion of DXM significantly improved clinical pregnancy rate (aOR: 3.188, 95% CI: 1.395-7.282, P = .006) and live birth rate (aOR: 3.176, 95% CI: 1.318-7.656, P = .010) in RRF patients with elevated uNK cells, but there was no significant association with miscarriage rate. Subgroup analysis revealed that intrauterine perfusion of DXM in patients with recurrent implantation failure (RIF) showed significant improvement in clinical pregnancy rate (aOR: 6.110, 95% CI: 1.511-24.713, P = .011) and live birth rate (aOR: 9.904, 95% CI: 1.963-49.968, P = .005), but there was insufficient evidence of benefit in recurrent pregnancy loss (RPL) patients. Additionally, uNK cell levels dropped to normal range was achieved in only 35.90% of RRF patients after DXM treatment, no significant difference was found in pregnancy outcomes among patients with different responsiveness to DXM treatment (all P > .05). CONCLUSION: Intrauterine perfusion of DXM was a promising and effective treatment to enhance clinical pregnancy rate and live birth rate in RRF women with abnormally elevated uNK cells, and RIF patients are more likely to benefit than RPL patients.

Lupus and recurrent pregnancy loss: the role of female sex hormones and B cells.

Systemic lupus erythematosus is a debilitating autoimmune disease characterized by uncontrolled activation of adaptive immunity, particularly B cells, which predominantly affects women in a 9 to 1 ratio compared to men. This stark sex disparity strongly suggests a role for female sex hormones in the disease's onset and progression. Indeed, it is widely recognized that estradiol not only enhances the survival of autoreactive B cells but also stimulates the production of autoantibodies associated with systemic lupus erythematosus, such as anti-nuclear antibodies and anti-dsDNA antibodies. Clinical manifestations of systemic lupus erythematosus typically emerge after puberty and persist throughout reproductive life. Furthermore, symptoms often exacerbate during the premenstrual period and pregnancy, as increased levels of estradiol can contribute to disease flares. Despite being fertile, women with lupus face a heightened risk of pregnancy-related complications, including pregnancy loss and stillbirth, which significantly surpass the rates observed in the healthy population. Therefore, this review aims to summarize and discuss the existing literature on the influence of female sex hormones on B-cell activation in patients with systemic lupus erythematosus, with a particular emphasis on their impact on pregnancy loss.

Platform for Quantitative Detection of Endometrial Immune Cells Based on Immunohistochemistry and Digital Image Analysis.

To evaluate the endometrial immune microenvironment of patients with recurrent miscarriage (RM), a digital immunohistochemistry image analysis platform was developed and validated to quantitatively analyze endometrial immune cells during the mid-luteal phase. All endometrium samples were collected during the mid-luteal phase of the menstrual cycle. Paraffin-embedded endometrial tissues were sectioned into 4 µm thick slides, and immunohistochemistry (IHC)staining was carried out for detecting endometrial immune cells, including CD56+ uNK cells, Foxp3+ Tregs, CD163+ M2 macrophages, CD1a+ DCs, and CD8+ T cells. The panoramic slides were scanned using a digital slide scanner and a commercial image analysis system was used for quantitative analysis. The percentage of endometrial immune cells was calculated by dividing the number of immune cells in the total endometrial cells. Using the commercial image analysis system, quantitative evaluation of endometrial immune cells, which are difficult or impossible to analyze with conventional image analysis, could be easily, and accurately analyzed. This methodology can be applied to quantitatively characterize the endometrium microenvironment, including interaction between immune cells, and its heterogeneity for different reproductive failure patients. The platform for quantitative evaluation of endometrial immune cells may be of important clinical significance for the diagnosis and treatment of RM patients.

An immune cell atlas reveals the dynamics of human macrophage specification during prenatal development.

Macrophages are heterogeneous and play critical roles in development and disease, but their diversity, function, and specification remain inadequately understood during human development. We generated a single-cell RNA sequencing map of the dynamics of human macrophage specification from PCW 4-26 across 19 tissues. We identified a microglia-like population and a proangiogenic population in 15 macrophage subtypes. Microglia-like cells, molecularly and morphologically similar to microglia in the CNS, are present in the fetal epidermis, testicle, and heart. They are the major immune population in the early epidermis, exhibit a polarized distribution along the dorsal-lateral-ventral axis, and interact with neural crest cells, modulating their differentiation along the melanocyte lineage. Through spatial and differentiation trajectory analysis, we also showed that proangiogenic macrophages are perivascular across fetal organs and likely yolk-sac-derived as microglia. Our study provides a comprehensive map of the heterogeneity and developmental dynamics of human macrophages and unravels their diverse functions during development.

Association between immunity and different clinical symptoms in patients with polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a disease with endocrine and metabolic disorders. The main symptoms are hyperandrogenemia (HA), insulin resistance (IR), and ovulation disorder. However, the pathogenesis and pathophysiological process of these major symptoms in PCOS are still not well defined. In recent studies, the chronic low-grade inflammatory state has become one of the factors affecting PCOS. Some alterable immune factors in PCOS, such as interleukin-15 and interleukin-1, have been identified to be related to androgen synthesis and insulin resistance in PCOS. In addition, a disturbed immune microenvironment in the ovary leads to impaired follicular growth and ovulation. Previous studies have roughly reviewed the relationship between immunity and PCOS. However, the link between the different clinical manifestations of PCOS and immunity has not been well explored and analyzed. The clinical presentation of each patient is diverse, and symptomatic treatment is mainly used. Therefore, this article reviews several representative immunological factors that affect these three symptoms to explore the underlying mechanism, which will be beneficial for developing new treatment strategies.

Characterization of progesterone-induced dendritic cells in metabolic and immunologic reprogramming.

The role of maternal-fetal immune tolerance in the establishment and maintenance of pregnancy has been well established. Dendritic cells (DCs) as a crucial part of the decidual microenvironment, have high plasticity in immunogenicity and tolerogenicity. The regulatory mechanisms of DCs phenotype or function at the maternal-fetal interface, however, have not been fully developed. Studies from the field of immunometabolism have highlighted that the metabolic pathways of DCs are closely associated with their immunity. Our previous study showed that progesterone (P4) up-regulated a series of enzymes involved in DCs mitochondrial oxidative phosphorylation and fatty acid metabolism. In this study, we confirmed that P4 induced significant alternations in DCs metabolic pathways, promoting their glycolysis, mitochondrial function, and the dependency and capacity of fatty acids as mitochondrial fuel. Moreover, P4 also increased the inhibitory molecule ILT4 expression on DCs and down-regulated the CD86, which may coordinate their immune tolerance function in pregnancy. Together, our study helps to understand the role of P4 in DCs metabolic and immunologic reprogramming and may provide novel insights into the hormonal immunometabolism regulation of DCs during normal pregnancy.

The function of decidua natural killer cells in physiology and pathology of pregnancy.

The role of decidual natural killer (dNK) cells in maintaining immune tolerance at the maternal-fetal interface during pregnancy is a significant topic in reproductive health. Immune tolerance is essential for a successful pregnancy and involves a complex immune response involving various immune cells and molecules. DNK cells comprise the largest population of lymphocyte subsets found in the decidua and play important roles in maintaining immune tolerance. These cells exert multiple functions to maintain homeostasis of the decidual microenvironment, including modulation of trophoblast invasion, promotion of fetal development, regulation of endometrial decidualization and spiral artery remodeling. DNK cells can also be divided into different subsets based on their functions as NKtolerant , NKcytotoxic , and NKregulatory cells. However, the relationship between dNK cells function and pregnancy outcomes is complex and poorly understood. In this review, we will focus on the physiological role of dNK cells during pregnancy and highlight the potential role in pathological pregnancies and therapeutic approaches.

Endometrial proteomic profile of patients with repeated implantation failure.

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

The effectiveness and safety of intrauterine infusion of autologous regulatory T cells (Tregs) in patients with recurrent pregnancy loss and low levels of endometrial FoxP3+ cells: A retrospective cohort study.

PROBLEM: Regulatory T cells (Tregs) are a specialized type of T cells that help maintain immune tolerance and homeostasis. The potential of Tregs cell-based therapies in treating diseases has been demonstrated in several clinical trials, which have shown promising outcomes and high safety in autoimmune diseases, transplant rejection, and graft-versus-host disease. However, their effectiveness and safety in improving endometrial receptivity and reducing pregnancy loss in human reproduction are unknown. METHOD OF STUDY: The study used a retrospective design and included patients with recurrent pregnancy loss (RPL) and lower levels of endometrial FoxP3+ Tregs. Patients in the Tregs group (n = 33) received intrauterine Tregs infusion three times during the follicular phase, while the control group (n = 28) did not receive any intrauterine infusion. RESULTS: The intrauterine infusion of autologous Tregs increased the levels of FoxP3+ Tregs and CD56+ NK cells. Patients in the Treg group had higher live birth rates and lower miscarriage rates, especially early miscarriage rates. However, the two groups had no differences in the implantation rate, clinical pregnancy rate, and percentage of preterm delivery. CONCLUSIONS: The findings suggest that intrauterine Tregs infusion may be a potential therapeutic approach for RPL. Further research in larger clinical trials is needed to confirm these findings.

γδ-T cell with high toxic potential was associated with recurrent miscarriage.

PROBLEM: RM is a common clinical disease in reproduction, affecting approximately 1%-3% of women worldwide. Previous studies have shown the role of peripheral blood γδ-T cells during physiological pregnancy. However, the relationship between the immune status of peripheral blood γδ-T cells and RM is still not well defined. METHOD OF STUDY: In this study, mid-luteal peripheral blood from 51 RM patients and 40 healthy women was collected to determine the immune status of γδ-T cells. The percentage of peripheral blood γδ-T cells, and the molecules mediating their toxic potential, including cytotoxic granules (perforin, granzyme B, and granulysin) and receptors (NKG2D, CD158a, and CD158b), were detected by flow cytometry. RESULTS: Compared to healthy control, an increase in the proportion of total CD3+ T cells in lymphocytes and a decrease in the ratio of γδ-T cells to CD3+ T cells were observed in patients with RM. The percentages of granzyme B+ γδ-T cells and CD158a+ γδ-T cells in total γδ-T cells or lymphocytes were significantly increased in patients with RM, compared with healthy control. Conversely, CD158b+ γδ-T cells in total γδ-T cells or lymphocytes were significantly decreased in the RM group. CONCLUSION: Increased peripheral blood γδ-T cell with high toxic potential was associated with RM.

Comparing the peri-implantation endometrial T-bet/GATA3 ratio between control fertile women and patients with recurrent miscarriage: establishment and application of a reference range.

STUDY QUESTION: Is the ratio of endometrial T-box expressed in T cell (T-bet) and GATA-binding protein 3 (GATA3) changed in patients with recurrent miscarriage (RM) compared to fertile controls? SUMMARY ANSWER: Our study showed a significantly higher T-bet/GATA3 ratio in patients with RM compared with fertile controls. WHAT IS KNOWN ALREADY: The endometrial T-bet (Th1 lineage-committed transcription factor)/GATA3 (Th2 lineage-committed transcription factor) ratio could represent the Th1/Th2 balance, which is particularly important for healthy pregnancy. However, a reliable reference range for the T-bet/GATA3 ratio during the peri-implantation period has not yet been established for use in clinical practice. STUDY DESIGN, SIZE, DURATION: This was a retrospective study carried out in a private fertility center. The control group included 120 women in couples undergoing IVF treatment for male infertility, who had experienced a live-birth baby following the first IVF cycle. The study group included 93 women diagnosed with RM that experienced at least two consecutive clinically spontaneous miscarriages before gestational week 12. The ratio of T-bet/GATA3 was calculated in the control group and RM group. PARTICIPANTS/MATERIALS, SETTING, METHODS: Endometrium samples were collected at mid-luteal phase of the menstrual cycle prior to IVF treatment or pregnancy. The percentage of T-bet+ and GATA3+ cells in total endometrial cells was analyzed using immunohistochemical staining and quantitative analysis. MAIN RESULTS AND THE ROLE OF CHANCE: Using the 95th percentile to define the upper limits of the endometrial T-bet/GATA3 ratio during the mid-luteal phase, the reference range of control fertile women was ≤0.22. Compared with the control group, the RM group exhibited a significantly higher T-bet/GATA3 ratio (P = 0.02), and 19.4% (18/93) women with RM exhibited a T-bet/GATA3 ratio above the reference range in the mid-luteal phase. LIMITATIONS, REASONS FOR CAUTION: All patients were recruited from a single center. The stability and clinical value of the endometrial T-bet/GATA3 ratio require further investigation. WIDER IMPLICATIONS OF THE FINDINGS: The present study suggests that an abnormal endometrial T-bet/GATA3 ratio may be one of the risk factors of RM. Further studies are needed to follow up the pregnancy outcomes in patients with RM with normal and abnormal endometrial T-bet/GATA3 ratio according to the reference range. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by Shenzhen Fundamental Research Program (JCYJ20180228164631121, JCYJ20190813161203606, JCYJ20220530172817039). There are no conflicts of interest to declare. TRIAL REGISTRATION NUMBER: N/A.