Identification of potential biomarkers and immune infiltration characteristics in recurrent implantation failure using bioinformatics analysis.

Introduction: Recurrent implantation failure (RIF) is a frustrating challenge because the cause is unknown. The current study aims to identify differentially expressed genes (DEGs) in the endometrium on the basis of immune cell infiltration characteristics between RIF patients and healthy controls, as well as to investigate potential prognostic markers in RIF. Methods: GSE103465, and GSE111974 datasets from the Gene Expression Omnibus database were obtained to screen DEGs between RIF and control groups. Gene Ontology analysis, Kyoto Encyclopedia of Genes and Genomes Pathway analysis, Gene Set Enrichment Analysis, and Protein-protein interactions analysis were performed to investigate potential biological functions and signaling pathways. CIBERSORT was used to describe the level of immune infiltration in RIF, and flow cytometry was used to confirm the top two most abundant immune cells detected. Results: 122 downregulated and 66 upregulated DEGs were obtained between RIF and control groups. Six immune-related hub genes were discovered, which were involved in Wnt/-catenin signaling and Notch signaling as a result of our research. The ROC curves revealed that three of the six identified genes (AKT1, PSMB8, and PSMD10) had potential diagnostic values for RIF. Finally, we used cMap analysis to identify potential therapeutic or induced compounds for RIF, among which fulvestrant (estrogen receptor antagonist), bisindolylmaleimide-ix (CDK and PKC inhibitor), and JNK-9L (JNK inhibitor) were thought to influence the pathogenic process of RIF. Furthermore, our findings revealed the level of immune infiltration in RIF by highlighting three signaling pathways (Wnt/-catenin signaling, Notch signaling, and immune response) and three potential diagnostic DEGs (AKT1, PSMB8, and PSMD10). Conclusion: Importantly, our findings may contribute to the scientific basis for several potential therapeutic agents to improve endometrial receptivity.

An active glutamine/α-ketoglutarate/HIF-1α axis prevents pregnancy loss by triggering decidual IGF1+GDF15+NK cell differentiation.

Deficiency of decidual NK (dNK) cell number and function has been widely regarded as an important cause of spontaneous abortion. However, the metabolic mechanism underlying the crosstalk between dNK cells and embryonic trophoblasts during early pregnancy remains largely unknown. Here, we observed that enriched glutamine and activated glutaminolysis in dNK cells contribute to trophoblast invasion and embryo growth by insulin-like growth factor-1 (IGF-1) and growth differentiation factor-15 (GDF-15) secretion. Mechanistically, these processes are dependent on the downregulation of EGLN1-HIF-1α mediated by α-ketoglutarate (α-KG). Blocking glutaminolysis with the GLS inhibitor BPTES or the glutamate dehydrogenase inhibitor EGCG leads to early embryo implantation failure, spontaneous abortion and/or fetal growth restriction in pregnant mice with impaired trophoblast invasion. Additionally, α-KG supplementation significantly alleviated pregnancy loss mediated by defective glutaminolysis in vivo, suggesting that inactivated glutamine/α-ketoglutarate metabolism in dNK cells impaired trophoblast invasion and induced pregnancy loss.

HIF1A-induced heme oxygenase 1 promotes the survival of decidual stromal cells against excess heme-mediated oxidative stress.

Heme oxygenase 1 (HO-1, encoded by the HMOX1 gene) is the rate-limiting enzyme that catalyzes heme degradation, and it has been reported to exert antioxidative effects. Recently, decidualization has been reported to confer resistance to environmental stress signals, protecting against oxidative stress. However, the effects and regulatory mechanism of HO-1 in decidual stromal cells (DSCs) during early pregnancy remain unknown. Here, we verified that the levels of HO-1 and heme in DSCs are increased compared with those in endometrial stromal cells. Additionally, the upregulation of HIF1A expression led to increased HMOX1 expression in DSCs possibly via nuclear factor erythroid 2-related factor (encoded by the NFE2L2 gene). However, addition of the competitive HO-1 inhibitor zinc protoporphyrin IX resulted in an increase in HIF1A expression. Hydrogen peroxide (H2O2) induced the production of reactive oxygen species (ROS), decreased the cell viability of DSCs in vitro, and upregulated the level of heme. As an HO-1 inducer, cobalt protoporphyrin IX decreased ROS production and significantly reversed the inhibitory effect of H2O2 on cell viability. More importantly, patients with unexplained spontaneous abortion had low levels of HO-1 that were insufficient to protect against oxidative stress. This study suggests that the upregulation of HO-1 expression via HIF1A protects DSCs against excessive heme-mediated oxidative stress. Furthermore, the excessive oxidative stress injury and impaired viability of DSCs associated with decreased HO-1 expression should be associated with the occurrence and/or development of spontaneous abortion.

Decidual IDO+ macrophage promotes the proliferation and restricts the apoptosis of trophoblasts.

Indoleamine 2, 3-dioxygenase (IDO), a tryptophan-catabolizing enzyme, is essential in physiological immunoregulation. The present research was conducted to elucidate the expression and roles of IDO in decidual macrophages (dMφ) during early pregnancy. Here, we observed a remarkable decrease of IDO+ dMφ from patients with unexplained recurrent spontaneous abortion (URSA). IDO+ dMφ displayed M2 phenotype with higher CD206, CD209 and CD163, and lower CD86. Interestingly, treatment with 1-methyl-d-tryptophan (1-MT, an IDO pathway inhibitor) led to the M1 bias of dMφ. Further analysis of the cytokine array and the qPCR showed decreased levels of trophoblast proliferation or invasion-related molecules (e.g., CXCL12 and BMP2) in 1-MT-treated dMφ. The data of co-culture system showed that 1-MT-pretreated dMφ decreased the proliferation and the expression of Ki-67 and Bcl-2, and increased cell apoptosis of HTR-8/Snveo cells. Additionally, the expression of IDO in U937 cells was up-regulated by decidual stromal cells (DSC) and HTR-8/Snveo cells in vitro, as well as estradiol and medroxyprogesterone. These data suggest that endocrine environment, DSC and trophoblasts should contribute to the high level of IDO in dMφ, and IDO+ dMφ with M2 dominant phenotype promote the survival of trophoblasts during early pregnancy. The abnormal lower level of IDO should trigger the dysfunction of dMφ, further suppress the survival of trophoblasts and increase the risk of miscarriage.

Kynurenine promotes the cytotoxicity of NK cells through aryl hydrocarbon receptor in early pregnancy.

During early pregnancy, decidual NK (dNK) cells play indispensable roles in many processes including the decidualization, the implantation, and the maintenance of immune tolerance. Abnormal cytotoxic activity of NK cells can cause recurrent spontaneous abortion (RSA), while the regulatory mechanism of NK cytotoxicity remains to be unclear. In this study, we found that kynurenine in decidua and villus was in a comparable level between patients with RSA and normal pregnancy women. However, the aryl hydrocarbon receptor (AhR) in decidual NK cells was significantly increased in RSA. Compared with AhR- NK cells, cytotoxic activity-related molecules (NKP30, NKP46, NKG2D, perforin, granzyme B and IFN-γ) was highly expressed in both AhR+ peripheral and decidual NK cells, and kynurenine stimulation promoted the expression of killer receptors and the cytoplasmic granules in an AhR-dependent manner. Stimulation with TNF-α, IL-ß and LPS upregulated the AhR expression in dNK cells in vitro. These results indicate that kyn/AhR signal enhances the cytotoxicity of NK cells, and increased expression of AhR may be an induction factor of RSA.

The IFN-γ-IDO1-kynureine pathway-induced autophagy in cervical cancer cell promotes phagocytosis of macrophage.

Background: Cervical cancer is a common malignant disease in female patients accompanied by activation of autophagy in tumor cells. However, the exact regulatory factors of autophagy and its effects on the immune response remain unknown. Methods: The induction of autophagy in HeLa and SiHa cells treated with IFN-γ, tryptophan depletion, kynurenine and epacadostat was detected by western blot analysis and by an autophagy detection kit. Following co-culture with pre-treated HeLa and SiHa cells, U937 cells were analyzed by flow cytometry to detect CD80, CD86, CD163 and CD206 expression and the induction of phagocytosis. Results: IFN-γ caused a significant increase in the autophagy levels of HeLa and SiHa cells by promoting indoleamine-2,3-dioxygenase-1 (IDO1) expression. The induction of phagocytosis in HeLa and SiHa cells and the expression levels of CD80 and CD86 in U937 cells were increased significantly following treatment with recombinant human IFN-γ. This effect was associated with the induction of tumor cell autophagy. IFN-γ treatment and IDO1 overexpression promoted tryptophan depletion and kynurenine accumulation in cervical cancer cells. The latter was more potent in inducing autophagy of cervical cancer cells and promoting phagocytosis of macrophages. In vivo, IDO1 overexpression restricted tumor growth in C57 mice and enhanced the induction of phagocytosis in macrophages. Conclusions: IFN-γ promoted induction of autophagy and macrophage phagocytosis in cervical cancer cells possibly via IDO1 expression and kynurenine metabolism.

Changes in subsets of immunocytes in endometrial hyperplasia.

PROBLEM: Endometrial hyperplasia (EH) is characterized by an endometrial gland-to-stroma ratio >1 and is one of the most common gynecological diseases in the world. The role of immunocyte subsets in the development of EH remains unknown. METHODS: Patients who underwent dilatation and curettage due to abnormal uterine bleeding were recruited in the present study. Alterations in the numbers of different types of immune cell subsets in the endometrium of patients were analyzed by flow cytometry. RESULTS: The present study included 48 patients who were divided into three groups, based on the pathological results: (a) proliferative period (PP, n = 12); (b) simple EH (SEH, n = 30); and (c) complex EH (CEH, n = 6). The results showed that immune cell subpopulations were significantly different between these three groups. Compared with the PP group, the proportion of CD45+ cells and neutrophils and the subtypes of T cells and macrophages were significantly increased in the SEH patients. Compared with the PP and SEH groups, subsets of immunocytes in the CEH group were significantly decreased, including the population of CD45+ cells and the subtypes of T cells and natural killer cells; in contrast, the proportion of macrophages was significantly increased. There were no significant differences between the other cell subsets in each group. CONCLUSION: The changes in immune cell subsets may be closely associated with the progression of EH. Although the specific role of different immune cell subsets in the development of the diseases requires further study, the changes in the proportions of immune cell subsets should not be ignored.

Collagen at the maternal-fetal interface in human pregnancy.

The survival and development of a semi-allogenic fetus during pregnancy require special immune tolerance microenvironment at the maternal fetal interface. During the establishment of a successful pregnancy, the endometrium undergoes a series of changes, and the extracellular matrix (ECM) breaks down and remodels. Collagen is one of the most abundant ECM. Emerging evidence has shown that collagen and its fragment are expressed at the maternal fetal interface. The regulation of expression of collagen is quite complex, and this process involves a multitude of factors. Collagen exerts a critical role during the successful pregnancy. In addition, the abnormal expressions of collagen and its fragments are associated with certain pathological states associated with pregnancy, including recurrent miscarriage, diabetes mellitus with pregnancy, preeclampsia and so on. In this review, the expression and potential roles of collagen under conditions of physiological and pathological pregnancy are systematically discussed.

Decidual stromal cells maintain decidual macrophage homeostasis by secreting IL-24 in early pregnancy.

PROBLEM: The state of self-renewal and self-maintain of decidual macrophages would be important for immune homeostasis at the maternal-fetal interface. The roles of interleukin (IL)-24 derived from decidual stromal cells (DSCs) on decidual macrophages have not been explored. METHOD OF STUDY: IL-24 expression in DSCs was interfered by lentivirus, and the transcription levels of IL-24 in DSCs were verified by real time (RT)-PCR. The levels of IL-24 receptors were determined by flow cytometry assays. The effect of recombination human IL-24 (rhIL-24) on the differentiation and apoptosis of macrophages was analyzed by flow cytometry in vitro. The viability of macrophages was detected by Cell Counting Kit-8 assays. RESULTS: The growth of DSCs was not affected obviously only by IL-24 knockdown while the growth of knockdown DSCs was inhibited significantly after co-cultured with decidual macrophages. The levels of IL-24 receptors (IL-20R1 and IL-22R1) were moderately to highly expressed on decidual macrophages and human macrophage cell line U937. The differentiation of decidual macrophages treated by rhIL-24 or co-cultured with IL-24 knockdown DSCs was not affected. Both apoptosis and viability of U937 cells were promoted by rhIL-24. The ratio of Bcl-2/Bax was down-regulated and Ki-67 was up-regulated by IL-24 treatment. The expression of Bcl-2/Bax was up-regulated while Ki-67 was down-regulated in U937 cells after co-cultured by IL-24 knockdown DSCs. CONCLUSION: IL-24 secreted by DSCs promotes the renewal and homeostasis of decidual macrophages possibly via down-regulating the ratio of Bcl-2/Bax and up-regulating of the expression of Ki-67 in early pregnancy.

Autophagy suppression of trophoblast cells induces pregnancy loss by activating decidual NK cytotoxicity and inhibiting trophoblast invasion.

BACKGROUND: The crosstalk between trophoblast cells and decidual NK cells plays an important role in the establishment and maintenance of normal pregnancy. Recent studies reported that autophagy can induce immune tolerance at the maternal fetal interface, while the mechanism remains unclear. METHODS: Autophagy levels in the villi of normal and recurrent spontaneous abortion (RSA) patients were detected by transmission electron microscopy. After co-cultured with trophoblast cells pretreated with 3-MA or rapamycin, NK cells were collected and the expression of killer receptors was detected by flow cytometry (FCM). The invasiveness of trophoblasts was tested by Cell invasion assay. RESULTS: Compared with elective pregnancy termination patients, the level of autophagy in the villi of RSA patients was significantly decreased. Inducing the autophagy level in trophoblast cells with rapamycin could significantly inhibit the cytotoxicity of NK cells in the co-culture system, and supplement of IGF-2 could rectify this effect. Meanwhile, autophagy suppression of trophoblasts reduced the level of Paternally Expressed Gene 10 (PEG10), leading to the impairment of trophoblast cell invasion. In addition, NK cells educated by autophagy-inhibited trophoblasts further decreased the proliferation and invasiveness of trophoblasts. In pregnant mice model, injection with 3-MA promoted the cytotoxicity of uterine NK cells, and increased the embryo absorption rate. CONCLUSION: Autophagy suppression of trophoblasts increase the cytotoxicity of NK cells and damage the trophoblasts invasion possibly by targeting IGF-2 and PEG10, respectively, which ultimately leads to miscarriage. Video Abstarct.

Myeloid-derived suppressor cells in obstetrical and gynecological diseases.

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of myeloid-origin cells which have immunosuppressive activities in several conditions, such as cancer and inflammation. Recent research has also associated MDSCs with numerous obstetrical and gynecological diseases. During pregnancy, MDSCs accumulate to ensure maternal-fetal immune tolerance, whereas they are decreased in patients who suffer from early miscarriage or pre-eclampsia. While the etiology of endometriosis is still unknown, abnormal accumulation of MDSCs in the peripheral blood and peritoneal fluid, alongside an increased level of reactive oxygen species (ROS), has been observed in these patients, which is central to the cellular immune regulations by MDSCs. Additionally, the regulation of MDSCs observed in tumours is also applicable to gynecologic neoplasms, including ovarian cancer and cervical cancer. More recently, emerging evidence has shown that there are high levels of MDSCs in premature ovarian failure (POF) and in vitro fertilization (IVF), but the underlying mechanisms are unknown. In this review, the generation and mechanisms of MDSCs are summarized. In particular, the modulation of these cells in immune-related obstetrical and gynecological diseases is discussed, including potential treatment options targeting MDSCs.

The role of CXC chemokine ligand 16 in physiological and pathological pregnancies.

The survival and development of a semi-allogeneic fetus during pregnancy require the involvement of a series of cytokines and immune cells. Chemokines are a type of special cytokine those were originally described as having a role in leukocyte trafficking. CXC chemokine ligand (CXCL) 16 is a member of the chemokine family, and CXC chemokine receptor (CXCR) 6 is its sole receptor. Emerging evidence has shown that CXCL16/CXCR6 is expressed at the maternal-fetal interface, by cell types that include trophoblast cells, decidual stroma cells, and decidual immune cells (eg, monocytes, γδT cells, and natural killer T (NKT) cells). The regulation of expression of CXCL16 is quite complex, and this process involves a multitude of factors. CXCL16 exerts a critical role in the establishment of a successful pregnancy through a series of molecular interactions at the maternal-fetal interface. However, an abnormal expression of CXCL16 is associated with certain pathological states associated with pregnancy, including recurrent miscarriage, pre-eclampsia, and gestational diabetes mellitus (GDM). In the present review, the expression and pleiotropic roles of CXCL16 under conditions of physiological and pathological pregnancy are systematically discussed.

Indoleamine 2,3-dioxygenase suppresses the cytotoxicity of 1 NK cells in response to ectopic endometrial stromal cells in endometriosis.

It has been reported that the impaired cytotoxicity of natural killer (NK) cells and abnormal cytokines that are changed by the interaction between ectopic endometrial cells and immune cells is indispensable for the initiation and development of endometriosis (EMS). However, the mechanism of NK cells dysfunction in EMS remains largely unclear. Here, we found that NK cells in peritoneal fluid from women with EMS highly expressed indoleamine 2,3-dioxygenase (IDO). Furthermore, IDO+NK cells possessed lower NKp46 and NKG2D but higher IL-10 than that of IDO-NK. Co-culture with endometrial stromal cells (nESCs) from healthy control or ectopic ESCs (eESCs) from women with EMS led to a significant increase in the IDO level in NK cells from peripheral blood, particularly eESCs, and an anti-TGF-ß neutralizing antibody suppressed these effects in vitro. NK cells co-cultured with ESC more preferentially inhibited the viability of nESCs than eESCs did, and pretreating with 1-methyl-tryptophan (1-MT), an IDO inhibitor, reversed the inhibitory effect of NK cells on eESC viability. These data suggest that ESCs induce IDO+NK cells differentiation partly by TGF-ß, and that IDO further restricts the cytotoxicity of NK cells in response to eESCs, which provides a potential therapeutic strategy for EMS patients, particularly those with a high number of impaired cytotoxic IDO+NK cells.

Bu-Shen-Yi-Qi formula impairs cytotoxicity of NK cells by up-regulating IDO expression in trophoblasts.

Recurrent spontaneous abortion (RSA) is a common health problem that affects about 5% of fertile women, when it occurs for unknown reasons, it is called unexplained recurrent spontaneous abortion (URSA). Traditional Chinese medicine, such as Bu-Shen-Yi-Qi formula which consists of Dangshen, Tusizi, Baizhu, Baishuo, Duzhong, Sangjisheng, Sugeng, and Tiaohuangqin, has played an invaluable role in the treatment of RSA since ancient times. However, the mechanism of how it takes effect is still not clear. To identify Bu-Shen-Yi-Qi formula could modulate immune condition at maternal-fetal interface via its effect on trophoblasts, HTR-8 of different treatment were co-cultured with peripheral or decidual natural killer (NK) cells, and the receptors such as NKP30 and NKP46 expression on NK cells were measured by flow cytometry (FCM). In this study, we found that herb medium could increase the IDO expression at appropriate concentrations. As an inhibitor of IDO, 1-MT could impair the inhibitory function of trophoblasts on NK cells. Furthermore, Bu-Shen-Yi-Qi formula could enhance the inhibitory function of trophoblasts on NK cells. In conclusion, Bu-Shen-Yi-Qi formula can inhibit NK cytotoxicity by up-regulating IDO expression in trophoblasts and play a role in the treatment of URSA patients.

Protopanaxadiol and metformin synergistically inhibit estrogen-mediated proliferation and anti-autophagy effects in endometrial cancer cells.

Metformin is commonly used for treating type II diabetes and has recently been reported to possess anti-proliferative properties that can be exploited for the prevention and treatment of a variety of cancers. Ginsenosides are the main effective biological components of ginseng. It has been reported that ginsenoside-Rb2 inhibit the invasiveness of endometrial cancer cells (ECC). The aim of this study was to investigate whether protopanaxadiol (PPD, a metabolite of ginsenosides) and metformin could synergistically regulate the biological behavior of ECC and analyze its possible mechanism. We here found that either metformin or PPD treatment led to a decreased viability and increased apoptosis and autophagy levels in ECC lines (Ishikawa and RL95-2 cells), and combination of PPD and metformin could enhance these effects induced by metformin or PPD in vitro. PPD and metformin significantly decreased the expression of estrogen receptor alpha (ERα) in Ishikawa and RL95-2 cells. Estrogen promoted the viability and restricted the apoptosis and autophagy of Ishikawa and RL95-2 cells, and PPD and metformin reversed these effects. In vivo trials showed that combination of PPD and metformin had the strongest activity of anti-tumor growth compared with PPD alone and metformin alone. These data suggest that PPD and metformin can be used together to play a more powerful anti-EC effect. Our study provides a scientific basis for the clinical application of PPD and metformin in the treatment of EC, especially in estrogen-dependent patients.