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.

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.

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.

Establishment of reference intervals of endometrial immune cells during the mid-luteal phase.

This study aimed to develop reference intervals (RIs) of endometrial immune cells in control infertile women during the mid-luteal phase, and compare with the proportion of endometrial immune cells in recurrent reproductive failure (RRF) patients. Endometrial tissue sections were obtained from 113 fertile women and 79 patients with RRF, including 40 patients who had suffered recurrent miscarriage (RM) and 39 patients with repeated implantation failure (RIF) during the mid-luteal phase of the menstrual cycle. Immunohistochemical staining and quantitative analysis of CD56+, Foxp3+, CD163+, CD1a+ and CD8+ cells were performed in endometriums. RIs of endometrial immune cells in control infertile women were as follows: CD56+ uterine natural killer cells (uNK) cells, 1.785-8.712%, forkhead box P3 (Foxp3)+ Tregs, 0.041-0.154%, CD163+ M2 macrophages, 0.298-1.492%, CD1a+ dendritic cells (DCs), 0.006-0.081% and CD8+ T cells, 0.674-2.504%. Compared with control infertile women, the percentage of endometrial CD56+ uNK cells, CD163+ M2 macrophages, CD1a+ DCs and CD8+ T cells were significantly increased in patients with RRF. Moreover, Foxp3+ Tregs levels were decreased in patients with RRF, and were statistically significant only in patients with RM. In conclusion, the RIs of endometrial immune cells were established in control infertile women during the mid-luteal phase, and a disordered endometrial immune microenvironment was observed in patients with RRF. The RIs of endometrial immune cells may be of important clinical significance for the treatment of RRF.

HSP70 regulates lipid metabolism of decidual macrophages to maintain normal pregnancy.

Dysfunction of decidual macrophages (dMs) are closely associated with recurrent pregnancy loss (RPL) which brings great suffering to patients. Metabolism is essential for regulating macrophage function. Identifying molecules that regulate metabolism and function of dMs is important to revealing the pathogenesis of RPL. Single-cell sequencing data of decidual immune cells from control and RPL patients were downloaded from the GSA database and converted into feature-barcode matrices by Cell Ranger. After quality control, removal of double cell and clustering of all cells, 3579 macrophages were extracted for normalisation, scaling and re-clustering. Function and metabolism analyses were performed by R packages AddMoudleScore, scMetabolism and AUCell. Metabolism clustering based on metabolism-related genes to clarify the metabolic characteristics of macrophages clusters. These results indicated that macrophage characterised by lipid metabolism were reduced in RPL and differential expression genes analysis found that HSP70 was significantly decreased in the RPL group. Furthermore, immunofluorescence staining demonstrated that HSP70 was significantly downregulated in dMs of RPL patients compared to controls. In conclusion, HSP70 may maintain normal pregnancy by regulating lipid metabolism of dMs. This study provides new insights into the molecular mechanisms regulating the function of dMs and provides a theoretical basis for the development of new therapies for RPL.

How do pre-pregnancy endometrial macrophages contribute to pregnancy?

Macrophages are professional phagocytes with a wide distribution in all tissues throughout the body. Macrophages play a crucial role in homeostasis and numerous physiological processes beyond innate and adaptive immunity, including cellular debris removal, metabolic regulation, tissue repair, and tissue remodeling. Uterine macrophages are a heterogeneous and highly plastic subset of immune cells regulated by the local microenvironment and, in addition to their anti-inflammatory and anti-infective functions, support the establishment and maintenance of pregnancy. Comprehensive reviews have summarized the role of decidual macrophages during pregnancy. However, the distribution of macrophages in the endometrium prior to pregnancy, their functional remodeling, and the knock-on effects on subsequent pregnancies have not been elucidated. In this review, we focus on 1) how the phenotypes of endometrial macrophages and their interactions with other endometrial cells indicate or contribute to the subsequent pregnancy, 2) the adaptive switching of endometrial macrophages during the initial establishment of pregnancy, 3) and the pregnancy complications and pregnancy-related disorders associated with endometrial macrophages.

Intrauterine infusion of human chorionic gonadotropin improves the endometrial FoxP3+ Tregs level and pregnancy outcomes in patients with lower endometrial FoxP3+ Tregs.

Intrauterine infusion of human chorionic gonadotropin (hCG) is suggested to have the capacity to recruit regulatory T cells (Tregs) in the endometrium. However, the pregnancy outcome for infertile women with a lower level of Tregs after hCG intrauterine infusion remains unknown. By examining the expression of FoxP3+ Tregs in the endometrium, this study aimed to evaluate the effectiveness of hCG intrauterine infusion in infertile women with lower endometrial Tregs in improving the Tregs level and the pregnancy outcome. This cohort study included 150 women aged 38 and younger with a lower FoxP3+ Tregs level in the mid-luteal phase. Patients were divided into the control group (n = 73), and hCG group (n = 77). Patients in the hCG group received three times of hCG intrauterine infusion during the follicular phase in the next biopsy and the embryo transfer cycles. The results showed that the endometrial FoxP3+ Tregs level increased significantly after hCG intrauterine infusion (P < 0.001). The effective rate in rescuing the endometrial Tregs level was 77.92% (60/77). The clinical pregnancy rate was increased significantly in the hCG group than the control group (54.8% vs. 74.0%, P = 0.014). The logistic regression result showed that hCG intrauterine infusion [adjusted odds ratio (aOR) (95% confidence interval (CI)) = 2.347 (1.119, 4.923), P = 0.024] and blastocyst transfer [aOR (CI) = 2.630 (1.090, 6.346)] are two independent factors contributing to the improved pregnancy outcome. These data highlighted the immune regulatory role of hCG intrauterine infusion and might facilitate the personal immunotherapy progress for unexplained infertility in patients with a lower endometrial Tregs level.

Effectiveness comparison between endometrial receptivity array, immune profiling and the combination in treating patients with multiple implantation failure.

PROBLEM: The clinical value of endometrial receptivity array (ERA), endometrial immune profiling, or a combination of both for multiple implantation failure patients is unclear. METHOD OF STUDY: One hundred and seventy-two women with a history of at least two or more consecutive implantation failures in IVF/ICSI treatment were included. According to patients' willingness, they were divided into four groups, 'no treatment', 'Immune Profiling', 'ERA' and 'ERA + Immune Profiling'. Endometrial biopsy was examined by ERA, immune profiling alone, or combination, and intention was adopted accordingly. Pregnancy outcomes were compared, and the association between ERA phases and endometrial immune profiling was also assessed. RESULTS: The overall incidence rate of the displaced window of implantation (WOI) and endometrial immune dysregulations were 84.9% and 75.3%, respectively. Implantation rate was significantly higher in the 'ERA + Immune Profiling' group than the 'no treatment' group (P = .007). Clinical pregnancy rate was somewhat improved in the three treatment groups but with a borderline significance (P = .071). After controlling for other confounders, 'ERA + Immune Profiling' treatment was associated with a higher pregnancy rate [aOR (95%CI)  = â€Š3.412 (1.387-8.395), P = .008]. There was no association between endometrial immune profiling and ERA phases. CONCLUSIONS: Our findings highlight the high incidence of displaced WOI and endometrial immune dysregulation in multiple implantation failure patients. The combination of ERA and endometrial immune profiling is more likely to have clinical value than ERA or immune profiling alone. These data suggested the unsubstitutability of ERA and endometrial immune profiling on the treatment outcome for multiple implantation failure patients.

Metabolic Reprogramming of Immune Cells at the Maternal-Fetal Interface and the Development of Techniques for Immunometabolism.

Immunity and metabolism are interdependent and coordinated, which are the core mechanisms for the body to maintain homeostasis. In tumor immunology research, immunometabolism has been a research hotspot and has achieved groundbreaking changes in recent years. However, in the field of maternal-fetal medicine, research on immunometabolism is still lagging. Reports directly investigating the roles of immunometabolism in the endometrial microenvironment and regulation of maternal-fetal immune tolerance are relatively few. This review highlights the leading techniques used to study immunometabolism and their development, the immune cells at the maternal-fetal interface and their metabolic features required for the implementation of their functions, explores the interaction between immunometabolism and pregnancy regulation based on little evidence and clues, and attempts to propose some new research directions and perspectives.

Impacts of Immunometabolism on Male Reproduction.

The physiological process of male reproduction relies on the orchestration of neuroendocrine, immune, and energy metabolism. Spermatogenesis is controlled by the hypothalamic-pituitary-testicular (HPT) axis, which modulates the production of gonadal steroid hormones in the testes. The immune cells and cytokines in testes provide a protective microenvironment for the development and maturation of germ cells. The metabolic cellular responses and processes in testes provide energy production and biosynthetic precursors to regulate germ cell development and control testicular immunity and inflammation. The metabolism of immune cells is crucial for both inflammatory and anti-inflammatory responses, which supposes to affect the spermatogenesis in testes. In this review, the role of immunometabolism in male reproduction will be highlighted. Obesity, metabolic dysfunction, such as type 2 diabetes mellitus, are well documented to impact male fertility; thus, their impacts on the immune cells distributed in testes will also be discussed. Finally, the potential significance of the medicine targeting the specific metabolic intermediates or immune metabolism checkpoints to improve male reproduction will also be reassessed.

Evaluation of endometrial immune status of polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is described as a low-grade chronic inflammatory state. However, there are limited studies on the specific endometrial immune status of PCOS patients. Whether this endometrial immune cell pattern is intrinsic to PCOS or the consequence of PCOS-associated obesity is a subject of debate. This study retrospectively included one hundred women diagnosed with PCOS and ninety-five normal fertile controls, which further divided into four groups (normoweight PCOS; overweight PCOS; normoweight control; overweight control) based on body mass index. The percentages of endometrial CD68+ macrophages (1.97 % vs. 1.17 %; P < 0.001), CD163+ M2 macrophages (2.30 % vs. 1.83 %; P = 0.001), CD1a+ iDCs (0.044 % vs. 0.029 %; P = 0.002), CD83+ mDCs (1.72 % vs. 1.07 %; P < 0.001) and CD8+ T cells (2.82 % vs. 1.95 %; P < 0.001) were significantly higher in normoweight PCOS women than normoweight controls. The percentage of CD68+ macrophages (2.09 % vs. 1.15 %; P < 0.001) was significantly higher in overweight PCOS women compared with overweight controls. In multivariant linear regression analysis, participants' PCOS status was the main predictors of endometrial CD68+ macrophages, CD163+ M2 macrophages, CD1a+ iDCs, CD83+ mDCs and CD8+ T cells in the whole study population. Additionally, in PCOS group, positive correlations were found between endometrial CD56+ NK, CD163+ M2 macrophages and QUICKI, indicating there was an association between endometrial immune cells and insulin resistance in PCOS women. Our study suggests that women with PCOS have altered endometrial immune cells, which may reflect a state of chronic low grade inflammation. The chronic inflammation, independent of obesity, may help understand the pathophysiologic mechanisms of intrinsic PCOS.

Identification of Profound Metabolic Alterations in Human Dendritic Cells by Progesterone Through Integrated Bioinformatics Analysis.

Maintaining the homeostasis of the decidual immune microenvironment at the maternal-fetal interface is essential for reproductive success. Dendritic cells (DCs) are the professional antigen-presenting cells and dominate this balance of immunogenicity and tolerance. Progesterone (P4) is highlighted as the "hormone of pregnancy" in most eutherian mammals because of its regulatory role in immune-endocrine behavior during pregnancy. Recent studies have shown that P4 is associated with the differentiation and function of DCs, however, the underlying mechanisms remain unidentified. In addition, while progress in the field of immunometabolism has highlighted the intimate connections between the metabolism phenotype and the immunogenic or tolerogenic fate of DCs, whether P4 can affect DCs metabolism and thus exert a functional manipulation has not yet been explored. In this study, we acquired human peripheral blood monocyte-derived DCs and conducted RNA sequencing (RNA-seq) on immature DCs (iDCs), P4-treated DCs (pDCs), and mature DCs (mDCs), aiming to comprehensively assess the effects of P4 on DCs. Our results showed pDCs performed a distinct differentially expressed genes (DEGs) profile compared with iDCs or mDCs. Further functional enrichment and weighted gene co-expression network (WGCNA) analysis found that these DEGs were related not only to the cellular components but also to the significant metabolic activities, including mitochondrial oxidative phosphorylation (OXPHOS) and fatty acid metabolism. In addition, these changes may be involved in the activation of various signaling pathways of PI3K/Akt/mTOR, AMPK/PGC1-α, and PPAR-γ. In summary, our work suggested that P4 induced profound metabolic alterations of mitochondrial OXPHOS and fatty acid metabolism in DCs. Our findings may provide new insights into the role of P4 in DCs.

New endometrial immune cell-based score (EI-score) for the prediction of implantation success for patients undergoing IVF/ICSI.

PROBLEM: Limited evidence revealed whether endometrial immunological factors contribute to implantation success in the first-attempted in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) patients. METHOD: The retrospective study was conducted among 139 eligible couples in the derivation cohort and 29 couples in the validation cohort. The expression of endometrial immune cell markers, including CD56 for natural killer cell, CD68 for pan-macrophage, CD163 for M2 macrophage, FOXP3 for regulatory T cell, CD1a for immature dendritic cell, CD83 for mature dendritic cell, CD8 for cytotoxic T cell and CD57 for mature NK and T cells were examined. RESULTS: The profiles of endometrial immune cells showed significant difference between the pregnant and implantation failure group in the derivation cohort. Multivariate logistic regression analysis showed that the percentage of CD68+ pan-macrophage and CD163+ M2-macrophage, as well as the transfer strategy are associated with implantation outcomes (P < 0.001, P = 0.029, P = 0.004, respectively). The EI-score was constructed by a nomogram and validated by a clinical decision curve based on CD68+ pan-macrophage, CD163+ M2-macrophage, and the transfer strategy. The performance of the EI-score in the deviation cohort showed a c-index of 0.82 (95% CI 0.74-0.89), and the accuracy rate reached 79.3% in the validation cohort. CONCLUSIONS: The endometrial immunological profiles in the mid-secretory phase is associated with implantation outcome in the first IVF/ICSI patients. EI-Score could help clinicians calculate the probability of implantation success via nomogram. Optimal decision point is determined by decision curve analysis and clinical impact curve, to aid in clinical decisions.