Single-cell characterization of self-renewing primary trophoblast organoids as modeling of EVT differentiation and interactions with decidual natural killer cells.

BACKGROUND: Extravillous trophoblast cell (EVT) differentiation and its communication with maternal decidua especially the leading immune cell type natural killer (NK) cell are critical events for placentation. However, appropriate in vitro modelling system and regulatory programs of these two events are still lacking. Recent trophoblast organoid (TO) has advanced the molecular and mechanistic research in placentation. Here, we firstly generated the self-renewing TO from human placental villous and differentiated it into EVTs (EVT-TO) for investigating the differentiation events. We then co-cultured EVT-TO with freshly isolated decidual NKs for further study of cell communication. TO modelling of EVT differentiation as well as EVT interaction with dNK might cast new aspect for placentation research. RESULTS: Single-cell RNA sequencing (scRNA-seq) was applied for comprehensive characterization and molecular exploration of TOs modelling of EVT differentiation and interaction with dNKs. Multiple distinct trophoblast states and dNK subpopulations were identified, representing CTB, STB, EVT, dNK1/2/3 and dNKp. Lineage trajectory and Seurat mapping analysis identified the close resemblance of TO and EVT-TO with the human placenta characteristic. Transcription factors regulatory network analysis revealed the cell-type specific essential TFs for controlling EVT differentiation. CellphoneDB analysis predicted the ligand-receptor complexes in dNK-EVT-TO co-cultures, which relate to cytokines, immunomodulation and angiogenesis. EVT was known to affect the immune properties of dNK. Our study found out that on the other way around, dNKs could exert effects on EVT causing expression changes which are functionally important. CONCLUSION: Our study documented a single-cell atlas for TO and its applications on EVT differentiation and communications with dNKs, and thus provide methodology and novel research cues for future study of human placentation.

Application of a JEG-3 organoid model to study HLA-G function in the trophoblast.

The human placenta is a unique temporary organ with a mysterious immune tolerance. The formation of trophoblast organoids has advanced the study of placental development. HLA-G is uniquely expressed in the extravillous trophoblast (EVT) and has been linked to placental disorders. With older experimental methodologies, the role of HLA-G in trophoblast function beyond immunomodulation is still contested, as is its role during trophoblast differentiation. Organoid models incorporating CRISPR/Cas9 technology were used to examine the role of HLA-G in trophoblast function and differentiation. JEG-3 trophoblast organoids (JEG-3-ORGs) were established that highly expressed trophoblast representative markers and had the capacity to differentiate into EVT. CRISPR/Cas9 based on HLA-G knockout (KO) significantly altered the trophoblast immunomodulatory effect on the cytotoxicity of natural killer cells, as well as the trophoblast regulatory effect on HUVEC angiogenesis, but had no effect on the proliferation and invasion of JEG-3 cells and the formation of TB-ORGs. RNA-sequencing analysis further demonstrated that JEG-3 KO cells followed similar biological pathways as their wild-type counterparts during the formation of TB-ORGs. In addition, neither HLA-G KO nor the exogenous addition of HLA-G protein during EVT differentiation from JEG-3-ORGs altered the temporal expression of the known EVT marker genes. Based on the JEG-3 KO (disruption of exons 2 and 3) cell line and the TB-ORGs model, it was determined that HLA-G has a negligible effect on trophoblast invasion and differentiation. Despite this, JEG-3-ORG remains a valuable model for studying trophoblast differentiation.

HLA-G: An Important Mediator of Maternal-Fetal Immune-Tolerance.

Maternal-fetal immune-tolerance occurs throughout the whole gestational trimester, thus a mother can accept a genetically distinct fetus without immunological aggressive behavior. HLA-G, one of the non-classical HLA class I molecules, is restricted-expression at extravillous trophoblast. It can concordantly interact with various kinds of receptors mounted on maternally immune cells residing in the uterus (e.g. CD4+ T cells, CD8+ T cells, natural killer cells, macrophages, and dendritic cells) for maintaining immune homeostasis of the maternal-fetus interface. HLA-G is widely regarded as the pivotal protective factor for successful pregnancies. In the past 20 years, researches associated with HLA-G have been continually published. Indeed, HLA-G plays a mysterious role in the mechanism of maternal-fetal immune-tolerance. It can also be ectopically expressed on tumor cells, infected sites and other pathologic microenvironments to confer a significant local tolerance. Understanding the characteristics of HLA-G in immunologic tolerance is not only beneficial for pathological pregnancy, but also helpful to the therapy of other immune-related diseases, such as organ transplant rejection, tumor migration, and autoimmune disease. In this review, we describe the biological properties of HLA-G, then summarize our understanding of the mechanisms of fetomaternal immunologic tolerance and the difference from transplant tolerance. Furthermore, we will discuss how HLA-G contributes to the tolerogenic microenvironment during pregnancy. Finally, we hope to find some new aspects of HLA-G in fundamental research or clinical application for the future.

The role of SATB1 in HTR8/SVneo cells and pathological mechanism of preeclampsia.

OBJECTIVE: Special AT-rich sequence binding protein 1 (SATB1) play potential roles in invasion and metastasis of tumor cells, and involves in human placental and fetal development. The objective of this study is to explore the role of SATB1 in migration and invasion of trophoblast and the potential mechanism. METHODS: Human placental tissues from first trimester, second trimester, term, and preeclampsia (PE) pregnancies were used to detect the expression and subcellular location of SATB1 and ß-catenin. The human trophoblast cell line HTR8/SVneo, which was treated with hypoxia/re-oxygenation (H/R), lithium chloride (LiCl) or SATB1-siRNA to investigate the role of SATB1 and ß-catenin signaling in human trophoblast function. RESULTS: We observed that SATB1 specifically localized within trophoblast cells of placenta tissues. Gradually reduced expression of SATB1 was observed during gestation, and lower expression were detected in placenta of PE compared with normal pregnancy. Moreover, the expression of SATB1 was decreased in H/R-treated HTR8/Svneo cells and villous explants. The Wnt/ß-catenin signaling pathway interacted with SATB1 expression and H/R treatment resulted in Wnt pathway inhibition in trophoblast, while lithium chloride (LiCl) treatment enhanced H/R-exposed HTR8/SVneo migration and invasion. Knockdown of SATB1 significantly reduced the level of ß-catenin and the migratory and invasive abilities of trophoblast. CONCLUSIONS: Our data suggested that oxidative stress reduced SATB1 leading to inhibition of Wnt/ß-catenin, and participate in the subdued migration and invasion of trophoblast, which indicated a potential pathological mechanism of PE.

SATB1 downregulation induced by oxidative stress participates in trophoblast invasion by regulating ß-catenin.

Preeclampsia (PE) is characterized by abnormal placentation in the early stages of pregnancy. Adequate migration and invasion of trophoblasts into the uterine wall and spiral arteries to form a functional maternal-fetal interface are pivotal for normal placentation, but the exact mechanism remains unclear. Growing evidence has revealed that special AT-rich sequence binding protein 1 (binds to nuclear matrix/scaffold-associating DNA) (SATB1) is a tumor promoter that participates in cancer cell migration and invasion. However, the expression and function of SATB1 in trophoblasts is unknown. Here, we characterize the stimulatory effect of SATB1 on the migration and invasion of trophoblasts and identify the regulatory events and downstream signaling components. Downregulated SATB1 was detected in PE placentae and villous explants cultured under hypoxia/reoxygenation (H/R) conditions. H/R-treated trophoblasts with lower SATB1 levels exhibited weaker invasive and growth capacities, whereas upregulation of the SATB1 level with recombinant SATB1 restored these impairments. This restoration was especially apparent with the sumoylation-deficient SATB1 variant, which contained a mutated site that blocked sumoylation. Moreover, the elevated concentration of SATB1 also increased the expression of ß-catenin, which is involved in human placental trophoblast invasion and differentiation is downregulated in PE. However, a specific activator, namely, lithium chloride (LiCl), increased ß-catenin expression but had no evident influence on SATB1 expression. Furthermore, upregulated SATB1 failed to restore trophoblast function when Wnt/ß-catenin was suppressed by dickkopf (Xenopus laevis) homolog 1, dickkopf 1 homolog (Xenopus laevis) (DKK1). Together, these data show that SATB1expression in the human placenta is affected by oxidative stress and might regulate the migration and invasion of trophoblasts via ß-catenin signaling.

[Expression and significance of SATB1 and wnt/ß-catenin signaling molecule in the placenta of preeclampsia].

OBJECTIVE: To explore the role of specific AT rich sequence binding protein 1(SATB1) and wnt/ß-catenin signaling pathways in the regulation of trophoblast invasion and its effect in the pathogenesis of preeclampsia. METHODS: From March 2013 to March 2014, 20 cases of human villous tissues (early pregnancy group) from women of 8-10 gestational weeks who received artificial abortion at the First Affiliated Hospital of Chongqing Medical University, 18 cases of placental tissues (mid-pregnancy group) from women of 18-20 gestational weeks who had labor induction by water bag, 20 cases of placental tissues (normal full-term group) from healthy full-term pregnancy women and 20 cases of placental tissues (preeclamptic group) from women with preeclampsia who received elective c-section in were collected. Immunohistochemical SP method was utilized to determine the position of SATB1 and beta-catenin in villous tissues or placental tissues. Western blot was performed to analyze the expression level of SATB1 and beta-catenin in villous tissues or placental tissues. Immunofluorescence assay was used to determine the location of SATB1 and ß-catenin in HTR8/SVneo cells. Western blot was performed to detect the expression level of SATB1 and beta-catenin in HTR8/SVneo cells cultured in normoxia and hypoxia reoxygenation (H/R) condition. Co-Immunoprecipitation detection was used to evaluate the interaction between SATB1 and ß-catenin in placental tissues in preeclamptic group and HTR8/SVneo cells in H/R group. Gelatin zymography analysis was used to measure the activity of matrix metalloproteinases (MMP)-2 and 9 in placental tissues from preeclamptic group and HTR8/SVneo cells in H/R group. RESULTS: (1) In the normal full-term group, rare syncytiotrophoblastic nodule, less fibrinoid necrosis and abundant numbers of capillary could be observed in placental tissues. In comparison, there were obvious vacuolation in the cytoblast of syncytiotrophoblast, rich fibrinoid necrosis and poor numbers of villous capillary in placental tissues from preeclamptic group. (2) SATB1 could be found by immunochemical staining in placenta or villous tissues from all the groups. The staining intensity of SATB1 were more weakening in preeclamptic group than in the normal full-term group. (3) ß-catenin could be found by immunochemical staining in placenta or villous tissues from all the groups. The staining intensity of ß-catenin were more weakening in preeclamptic group than in the normal full-term group. (4) The protein expression levels of SATB1 in early pregnancy group, mid-pregnancy group, normal full-term group and preeclamptic group were 0.300 ± 0.009, 0.271±0.015, 0.238±0.018 and 0.153±0.007, respectively. The protein levels of ß-catenin among the above groups were 0.743±0.041, 0.648±0.021, 0.549±0.069 and 0.269±0.047, respectively. Both the expression of SATB1 and ß-catenin protein were significant decreased in placental tissues from preeclamptic group compared with the other three groups. (5) The SATB1 and ß-catenin protein was located in nucleus of trophoblast and a small amount was in the cytoplasm. The fluorescence intensity of both SATB1 and ß-catenin in the H/R group were significantly decreasing when compared to the normoxia group. (6) HTR8/SVneo cells in H/R group showed a significant decrease in both SATB1 and ß-catenin protein levels when compared to the normoxia group. The protein level of SATB1 in the normoxia group was 0.213±0.005, while was 0.083±0.021 in the H/R group. The protein level of ß-catenin in the normoxia group was 0.797±0.081, and was 0.543±0.131 in the H/R group. (7) There was an interaction between SATB1 and ß-catenin in placental tissues from the preeclamptic group and HTR8/SVneo cells exposed by H/R. (8) The enzymatic activity of MMP-2 and MMP-9 protein were decreased significantly in placental tissues from the preeclamptic group (2.251±0.310, 1.447±0.102, respectively) when compared to the normal full-term group (7.098±0.451, 5.502±0.197, respectively). MMP-2 and MMP-9 were significantly decreased in the H/R group (0.471±0.104, 0.297±0.103, respectively) when compared to the normoxia group (0.842±0.209, 0.595±0.100, respectively). CONCLUSION: The expression of SATB1 decreased in the placenta of preeclampsia. This may influence the activity of MMP-2 and 9 by regulating Wnt/ß-catenin signaling pathways, affect trophoblast invasion and eventually result in preeclampsia.

The Role of Laminin α4 in Human Umbilical Vein Endothelial Cells and Pathological Mechanism of Preeclampsia.

Preeclampsia (PE) is associated with defective placental angiogenesis and poor placentation. Laminins are the main noncollagenous glycoproteins in basement membranes, and laminin α4 (LAMA4) promotes the migration, proliferation, and survival of various cells. The primary purpose of this study is to investigate the role of LAMA4 in human umbilical vein endothelial cells (HUVECs) function during the development of PE. We found expression levels of LAMA4 in human PE placentas were significantly lower compared to the control placentas. The LAMA4 small-interfering RNA transfection and hypoxia-reoxygenation (H/R) intervention reduced the migratory and tube formation abilities of HUVECs. The mitogen-activated protein kinase (MAPK) signaling pathways interacted with LAMA4 expression and H/Rexposure led to MAPK pathways activation in HUVECs. We demonstrated that LAMA4 is very crucial in promoting the functions of endothelial cells. Oxidative stress plays a vital role in controlling expression of LAMA4 through MAPK signaling pathways, which suggests a possible pathological mechanism of PE.

IL-27 activates human trophoblasts to express IP-10 and IL-6: implications in the immunopathophysiology of preeclampsia.

PURPOSE: To investigate the effects of IL-27 on human trophoblasts and the underlying regulatory signaling mechanisms in preeclampsia. METHODS: The expression of IL-27 and IL-27 receptor (WSX-1) was studied in the placenta or sera from patients with preeclampsia. In vitro, we investigated the effects of IL-27 alone or in combination with inflammatory cytokine tumor necrosis factor (TNF-α) on the proinflammatory activation of human trophoblast cells (HTR-8/SVneo) and the underlying intracellular signaling molecules. RESULTS: The expression of IL-27 and IL-27 receptor α (WSX-1) was significantly elevated in the trophoblastic cells from the placenta of patients with preeclampsia compared with control specimens. In vitro, IL-27 could induce the expression of inflammatory factors IFN-γ-inducible protein 10 (CXCL10/IP-10) and IL-6 in trophoblasts, and a synergistic effect was observed in the combined treatment of IL-27 and TNF-α on the release of IP-10 and IL-6. Furthermore, the production of IP-10 and IL-6 stimulated by IL-27 was differentially regulated by intracellular activation of phosphatidylinositol 3-OH kinase-AKT, p38MAPK, and JAK/STAT pathways. CONCLUSIONS: These results provide a new insight into the IL-27-activated immunopathological effects mediated by distinct intracellular signal transduction molecules in preeclampsia.