Decreased USP2a Expression Inhibits Trophoblast Invasion and Associates With Recurrent Miscarriage

Deficiency of UCHL1 results in insufficient decidualization accompanied by impaired dNK modulation and eventually miscarriage

BACKGROUND

Miscarriage is a frustrating complication of pregnancy that is common among women of reproductive age. Insufficient decidualization which not only impairs embryo implantation but disturbs fetomaternal immune-tolerance, has been widely regarded as a major cause of miscarriage; however, the underlying mechanisms resulting in decidual impairment are largely unknown.

METHODS

With informed consent, decidual tissue from patients with spontaneous abortion or normal pregnant women was collected to detect the expression profile of UCHL1. Human endometrial stromal cells (HESCs) were used to explore the roles of UCHL1 in decidualization and dNK modulation, as well as the mechanisms involved. C57/BL6 female mice (7-10 weeks old) were used to construct pregnancy model or artificially induced decidualization model to evaluate the effect of UCHL1 on mice decidualization and pregnancy outcome.

RESULTS

The Ubiquitin C-terminal hydrolase L1 (UCHL1), as a deubiquitinating enzyme, was significantly downregulated in decidua from patients with miscarriage, along with impaired decidualization and decreased dNKs. Blockage of UCHL1 led to insufficient decidualization and resultant decreased expression of cytokines CXCL12, IL-15, TGF-β which were critical for generation of decidual NK cells (dNKs), whereas UCHL1 overexpression enhanced decidualization accompanied by increase in dNKs. Mechanistically, the promotion of UCHL1 on decidualization was dependent on its deubiquitinating activity, and intervention of UCHL1 inhibited the activation of JAK2/STAT3 signaling pathway, resulting in aberrant decidualization and decreased production of cytokines associated with dNKs modulation. Furthermore, we found that inhibition of UCHL1 also disrupted the decidualization in mice and eventually caused adverse pregnancy outcome.

CONCLUSIONS

UCHL1 plays significant roles in decidualization and dNKs modulation during pregnancy in both humans and mice. Its deficiency indicates a poor pregnancy outcome due to defective decidualization, making UCHL1 a potential target for the diagnosis and treatment of miscarriage.

Single-cell transcriptomic analysis of decidual immune cell landscape in the occurrence of adverse pregnancy outcomes induced by Toxoplasma gondii infection

BACKGROUND

Toxoplasma gondii is an obligate intracellular parasite that can lead to adverse pregnancy outcomes, particularly in early pregnancy. Previous studies have illustrated the landscape of decidual immune cells. However, the landscape of decidual immune cells in the maternal-fetal microenvironment during T. gondii infection remains unknown.

METHODS

In this study, we employed single-cell RNA sequencing to analyze the changes in human decidual immune cells following T. gondii infection. The results of scRNA-seq were further validated with flow cytometry, reverse transcription-polymerase chain reaction, western blot, and immunofluorescence staining.

RESULTS

Our results showed that the proportion of 17 decidual immune cell clusters and the expression levels of 21 genes were changed after T. gondii infection. Differential gene analysis demonstrated that T. gondii infection induced the differential expression of 279, 312, and 380 genes in decidual NK cells (dNK), decidual macrophages (dMφ), and decidual T cells (dT), respectively. Our results revealed for the first time that several previously unknown molecules in decidual immune cells changed following infection. This result revealed that the function of maternal-fetal immune tolerance declined, whereas the killing ability of decidual immune cells enhanced, eventually contributing to the occurrence of adverse pregnancy outcomes.

CONCLUSIONS

This study provides valuable resource for uncovering several novel molecules that play an important role in the occurrence of abnormal pregnancy outcomes induced by T. gondii infection.

MANF Promotes Unexplained Recurrent Miscarriages by Interacting with NPM1 and Downregulating Trophoblast Cell Migration and Invasion

Dysplasia and invasive defects in early trophoblasts contribute to unexplained recurrent miscarriages (URMs). Mesencephalic astrocyte-derived neurotrophic factor (MANF) inhibits migration and invasion in some cancer cells, but its role in pregnancy-related diseases remains unresolved. Here, we found that MANF levels in the peripheral blood and aborted tissue of URM women were higher than in normal controls, irrespective of pregnancy or miscarriage. We confirm the interaction between MANF and nucleophosmin 1 (NPM1) in trophoblasts of URM patients, which increases the ubiquitination degradation of NPM1, leading to upregulation of the p53 signaling pathway and inhibition of cell proliferation, migration, and invasion ability. Using a URM mouse model, we found that MANF downregulation resulted in reduced fetal resorption; however, concomitant NPM1 downregulation led to increased abortion rates. These data indicate that MANF triggers miscarriage via NPM1 downregulation and p53 activation. Thus, MANF downregulation or disruption of the MANF-NPM1 interaction could be targets for URM therapeutics.

Gene pathway analysis of the endometrium at the start of the window of implantation in women with unexplained infertility and unexplained recurrent pregnancy loss: is unexplained recurrent pregnancy loss a subset of unexplained infertility?

This study aims to understand differences/similarities in the genetic profile of the endometrium at the start of window of implantation (WOI) in women with unexplained infertility (UI) and unexplained recurrent pregnancy loss (uRPL). Differentially expressed genes (DEGs) from the endometrium were evaluated using gene expression array and pathway enrichment analysis was performed to analyse gene expression pathways involved in both conditions. We found 2,171 genes arranged in 117 pathways and 730 genes arranged in 33 pathways differentially expressed in endometrium of patients in UI and uRPL, respectively. Complement-coagulation cascades, morphine addiction pathway, and PI3K-Akt signalling pathway were predominantly differentially expressed in UI. Cancer pathways, NF-κB signalling pathway, and actin cytoskeleton regulation pathway showed significant changes in uRPL. Forty-eight percent of DEGs and 84% of differentially expressed pathways in uRPL were found in the endometrium of UI patients. Unexpected close association in gene expression pathways between UI and uRPL is observed supporting the hypothesis 'uRPL is a clinical subset of UI'. Yet 100% DEGs overlap wasn't found suggesting the endometrium has still some different gene expression patterns at start of WOI in UI and uRPL. Lastly, diagnostic tools may be developed for uRPL because more specific genes-pathways are involved compared with UI, which shows broader genetic expression profile.

Endometrial TGFβ signaling fosters early pregnancy development by remodeling the fetomaternal interface

The endometrium is a unique and highly regenerative tissue with crucial roles during the reproductive lifespan of a woman. As the first site of contact between mother and embryo, the endometrium, and its critical processes of decidualization and immune cell recruitment, play a leading role in the establishment of pregnancy, embryonic development, and reproductive capacity. These integral processes are achieved by the concerted actions of steroid hormones and a myriad of growth factor signaling pathways. This review focuses on the roles of the transforming growth factor β (TGFβ) pathway in the endometrium during the earliest stages of pregnancy through the lens of immune cell regulation and function. We discuss how key ligands in the TGFβ family signal through downstream SMAD transcription factors and ultimately remodel the endometrium into a state suitable for embryo implantation and development. We also focus on the key roles of the TGFβ signaling pathway in recruiting uterine natural killer cells and their collective remodeling of the decidua and spiral arteries. By providing key details about immune cell populations and TGFβ signaling within the endometrium, it is our goal to shed light on the intricate remodeling that is required to achieve a successful pregnancy.

Exploring maternal-fetal interface with in vitro placental and trophoblastic models

The placenta, being a temporary organ, plays a crucial role in facilitating the exchange of nutrients and gases between the mother and the fetus during pregnancy. Any abnormalities in the development of this vital organ not only lead to various pregnancy-related disorders that can result in fetal injury or death, but also have long-term effects on maternal health. In vitro models have been employed to study the physiological features and molecular regulatory mechanisms of placental development, aiming to gain a detailed understanding of the pathogenesis of pregnancy-related diseases. Among these models, trophoblast stem cell culture and organoids show great promise. In this review, we provide a comprehensive overview of the current mature trophoblast stem cell models and emerging organoid models, while also discussing other models in a systematic manner. We believe that this knowledge will be valuable in guiding further exploration of the complex maternal-fetal interface.

GDF15 deficiency hinders human trophoblast invasion to mediate pregnancy loss through downregulating Smad1/5 phosphorylation

Growth differentiation factor 15 (GDF15) belongs to the Transforming growth factor β(TGF-β) superfamily. The decrease of GDF15 in the serum of pregnant women was associated with miscarriage. Both IHC and ELISA assays showed that GDF15 in trophoblast tissue and serum of pregnant women who miscarried was significantly lower than in those who had a live birth. GDF15 deficiency was associated with embryo resorption in GDF15 knockout mice through CRIPSR editing. In addition, the migration and invasion ability of HTR-8/SVneo and JEG-3 cells were promoted by GDF15. Mechanistically, GDF15 increased Smad1/5 phosphorylation, resulting in upregulating SNAI1/2, VIMENTIN and downregulating E-CADHERIN. A dual-luciferase reporter assay confirmed that Smad-binding elements (SBE) and/or GC-rich motifs were activated and target genes such as SNAI1/2, SERPINE1, and TIMP3 were transcriptionally regulated by GDF15/Smad5 signaling. Therefore, our data revealed a crucial role of GDF15 on invasion of trophoblast by upregulating the activity of TGF-β/Smad1/5 pathway.

ELF1/PRR11/ARP2/3 promoted trophoblast cells proliferation and motility in early pregnancy

BACKGROUND/OBJECTIVE

Early pregnancy loss (EPL) is a common adverse pregnancy outcome with an incidence of approximately 10-30%. There are many factors that cause EPL, among which the lack of proliferation and invasive properties of trophoblast cells can lead to embryonic development. Therefore, in this study, the molecular biology of trophoblast cells was investigated.

METHODS

Placental villous tissues from EPL patients were collected to explore ELF1 and PRR11 gene expression. The proliferation and migration of trophoblast cells were assessed by MTT, crystalline violet staining, and traswell assays, respectively. Western blotting and RT-qPCR were performed to investigate the relationship between ELF1, PRR11, and ARP2/3. F-actin polymerization and FAK activation were evaluated by immunofluorescence and western blotting. Ultimately, ELF1/PRR11/ARP2/3 expression was verified in the EPL mice model RESULTS: ELF1 and PRR11 were lowly expressed in placental villous tissues from EPL. The overexpression of ELF1 and PRR11 promoted proliferation and migration of trophoblast cells. Moreover, while ELF1 bound to the PRR11 promoter and promoted transcriptional activation. Finally, ELF1/PRR11/ARP2/3 showed low expression in the placental tissue of EPL mice.

CONCLUSION

Our study suggested that PRR11 promoted the motility of trophoblast cells by binding to the ARP2/3 complex to promote F-actin polymerization and FAK activation. In addition, ELF1 bound to the initiation site of PRR11 to promote its transcription. ELF1/PRR11/ARP2/3 may play an important role in EPL.

Decreased B7-H3 promotes unexplained recurrent miscarriage via RhoA/ROCK2 signaling pathway and regulates the secretion of decidual NK cells†

The cause for at least 50% of recurrent miscarriages is unclear, which is defined as unexplained recurrent miscarriages. The B7-H1 (PD-L1), a molecule of the B7 family, promotes tumor development by modulating immune evasion, and recent researchers have also attached importance to the role of B7-H3, another molecule of B7 family, in tumor. Based on the similarity between growth and immune response in tumors and pregnancy, we first explored the role of B7-H3 in unexplained recurrent miscarriages. We found reduced levels of B7-H3 in the villus tissue of unexplained recurrent miscarriage patients, and it was mainly expressed on the cell membrane of extravillous trophoblasts. Further, the HTR-8/SVneo and JEG-3 cells were selected to explore the role of B7-H3 in proliferation, apoptosis, tube formation, migration, and invasion. We found that B7-H3 regulated trophoblast migration and invasion via RhoA/ROCK2 signaling pathway. Inflammatory cytokines were detected through enzyme-linked immunosorbent assay after co-culturing with decidual natural killer cells and B7-H3-knockout JEG-3. Results showed that B7-H3 inhibited IL-8 and IP-10 secretion from the decidual natural killer cells. In a CBA/J × DBA/2 abortion-prone mice model, treatment with B7-H3-Fc protein successfully reduced the rate of embryo resorption. In conclusion, our results revealed a possible mechanism by which decreased B7-H3 on trophoblasts of unexplained recurrent miscarriages inhibited trophoblast migration and invasion and increased IL-8 and IP-10 secretion from the decidual natural killer cells. Furthermore, B7-H3 may be a promising new therapeutic target in unexplained recurrent miscarriage patients.

LDHA deficiency inhibits trophoblast proliferation via the PI3K/AKT/FOXO1/CyclinD1 signaling pathway in unexplained recurrent spontaneous abortion

Dysregulated trophoblast proliferation, invasion, and apoptosis may cause several pregnancy-associated complications, such as unexplained recurrent spontaneous abortion (URSA). Recent studies have shown that metabolic abnormalities, including glycolysis inhibition, may dysregulate trophoblast function, leading to URSA. However, the underlying mechanisms remain unclear. Herein, we found that lactate dehydrogenase A (LDHA), a key enzyme in glycolysis, was significantly reduced in the placental villus of URSA patients. The human trophoblast cell line HTR-8/SVneo was used to investigate the possible LDHA-mediated regulation of trophoblast function. LDHA knockdown in HTR-8/SVneo cells induced G0/G1 phase arrest and increased apoptosis, whereas LDHA overexpression reversed these effects. Next, RNA sequencing combined with Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that the PI3K/AKT signaling pathway is potentially affected by downstream genes of LDHA. Especially, we found that LDHA knockdown decreased the phosphorylation levels of PI3K, AKT, and FOXO1, resulting in a significant downregulation of CyclinD1. In addition, treatment with an AKT inhibitor or FOXO1 inhibitor also verified that the PI3K/AKT/FOXO1 signaling pathway influenced the gene expression of CyclinD1 in trophoblast. Moreover, p-AKT expression correlated positively with LDHA expression in syncytiotrophoblasts and extravillous trophoblasts in first-trimester villus. Collectively, this study revealed a new regulatory pathway for LDHA/PI3K/AKT/FOXO1/CyclinD1 in the trophoblast cell cycle and proliferation.

Decidual macrophages in recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) is defined as two or more pregnancy loss, affecting the happiness index of fertility couples. The mechanisms involved in the occurrence of RSA are not clear to date. The primary problem for the maternal immune system is how to establish and maintain the immune tolerance to the semi-allogeneic fetuses. During the pregnancy, decidual macrophages mainly play an important role in the immunologic dialogue. The purpose of this study is to explore decidual macrophages, and to understand whether there is a connection between these cells and RSA by analyzing their phenotypes and functions. Pubmed, Web of Science and Embase were searched. The eligibility criterion for this review was evaluating the literature about the pregnancy and macrophages. Any disagreement between the authors was resolved upon discussion and if required by the judgment of the corresponding author. We summarized the latest views on the phenotype, function and dysfunction of decidual macrophages to illuminate its relationship with RSA.

Crosstalk Between Trophoblast and Macrophage at the Maternal-Fetal Interface: Current Status and Future Perspectives

The immune tolerance microenvironment is crucial for the establishment and maintenance of pregnancy at the maternal-fetal interface. The maternal-fetal interface is a complex system containing various cells, including lymphocytes, decidual stromal cells, and trophoblasts. Macrophages are the second-largest leukocytes at the maternal-fetal interface, which has been demonstrated to play essential roles in remodeling spiral arteries, maintaining maternal-fetal immune tolerance, and regulating trophoblast's biological behaviors. Many researchers, including us, have conducted a series of studies on the crosstalk between macrophages and trophoblasts at the maternal-fetal interface: on the one hand, macrophages can affect the invasion and migration of trophoblasts; on the other hand, trophoblasts can regulate macrophage polarization and influence the state of the maternal-fetal immune microenvironment. In this review, we systemically introduce the functions of macrophages and trophoblasts and the cell-cell interaction between them for the establishment and maintenance of pregnancy. Advances in this area will further accelerate the basic research and clinical translation of reproductive medicine.