Role of osteopontin in decidualization and pregnancy success

Endometrial Elasticity is an Ultrasound Marker for Predicting Clinical Pregnancy Outcomes after Embryo Transfer

Endometrial elasticity is a potential new marker for assessing endometrial receptivity and pregnancy outcomes based on endometrial thickness and type. Currently, little research has been conducted on the elasticity of the endometrium using shear wave elasticity imaging (SWEI). This study aimed to explore whether endometrial elasticity is an ultrasound marker for predicting clinical pregnancy outcomes after embryo transfer. A total of 245 infertile women underwent ultrasonography before embryo transfer at the Peking University Third Hospital. We compared the endometrial elasticity and sub-endometrial blood flow rate using SWEI in the groups with different pregnancy outcomes. Trends in clinical pregnancy outcomes across the quartiles of endometrial elasticity in the fundus of the uterus (E1) were assessed. Logistic regression analysis was performed to obtain odds ratios for clinical pregnancy outcomes based on the quartiles of E1, with or without adjusting for potential confounding variables. Women in the clinical pregnancy group had higher E1 values and sub-endometrial blood flow rates in the uterine fundus than those in the non-pregnancy group. Women in the highest quartile of E1 had the most favorable clinical pregnancy rates. Endometrial elasticity measured using SWEI is a promising ultrasound marker for predicting clinical pregnancy outcomes after embryo transfer.

Elevated high-mannose N-glycans hamper endometrial decidualization

Decidualization of endometrial stromal cells is a hallmark of endometrial receptivity for embryo implantation, and dysfunctional decidualization is associated with pregnancy failure. Protein glycosylation is an important posttranslational modification that affects the structure and function of glycoproteins. Our results showed that high-mannose epitopes were elevated in the decidual tissues of miscarriage patients compared with early pregnant women by Lectin microarray. Furthermore, the level of mannosyl-oligosaccharide α-1,2 mannosidase IA (MAN1A1), a key enzyme for high-mannose glycan biosynthesis, was decreased in the decidual tissues of miscarriage patients. Screening of lncRNAs showed that lncNEAT1 level was increased in the serum and decidua of miscarriage patients, and negatively correlated with MAN1A1 expression. The results also revealed that specific binding of lncNEAT1 with nucleophosmin (NPM1)-SP1 transcription complex inhibited MAN1A1 expression and hampered endometrial decidualization and embryo implantation potential. The study suggests the new insights into the function of high-mannose glycans/MAN1A1 modification during endometrial decidualization.

Immunoexpression of neuropilin-1 in the chorionic villi of HIV-infected preeclamptic South African women of African ancestry

Neuropilin-1 (NRP-1) is an essential regulator of maternal immune tolerance, placentation, and angiogenesis. Its dysregulation in preeclampsia (PE) and human immunodeficiency virus (HIV) infection implicates NRP-1 in disease susceptibility and progression. Therefore, this study investigates placental NRP-1 immunoexpression in HIV-complicated preeclamptic pregnancies in South African women of African ancestry receiving antiretroviral therapy. Immunohistochemistry of recombinant anti-neuropilin-1 antibody was performed on placental tissue from 30 normotensive and 60 early onset (EOPE) and late-onset (LOPE) preeclamptic women stratified by HIV status. Qualitative analysis of NRP-1 immunostaining within the chorionic villi revealed a predominant localization in trophoblasts and syncytial knots as well as endothelial, fibroblast-like, and Hofbauer cells. Following morphometric evaluation, we report that PE and HIV infection and/or antiretroviral usage independently downregulate placental NRP-1 immunoexpression; however, as a comorbidity, this decline is further augmented within the conducting and exchange villi. Furthermore, reduced immunoexpression of NRP-1 in EOPE compared with LOPE villi may be due to maternal-fetal maladaptation. It is plausible that the decreased NRP-1 immunoexpression in PE placentae facilitates syncytiotrophoblast apoptosis and subsequent deportation of NRP-1 into the maternal circulation, contributing to the anti-angiogenic milieu of PE. We hypothesize that the intense NRP-1 immunoreactivity observed in Hofbauer cells at the maternal-fetal interface may contribute to the natural prevention mechanism of HIV vertical transmission.

Decoding the endometrial niche of Asherman's Syndrome at single-cell resolution

Asherman's Syndrome is characterized by intrauterine adhesions or scarring, which cause infertility, menstrual abnormalities, and recurrent pregnancy loss. The pathophysiology of this syndrome remains unknown, with treatment restricted to recurrent surgical removal of intrauterine scarring, which has limited success. Here, we decode the Asherman's Syndrome endometrial cell niche by analyzing data from over 200,000 cells with single-cell RNA-sequencing in patients with this condition and through in vitro analyses of Asherman's Syndrome patient-derived endometrial organoids. Our endometrial atlas highlights the loss of the endometrial epithelium, alterations to epithelial differentiation signaling pathways such as Wnt and Notch, and the appearance of characteristic epithelium expressing secretory leukocyte protease inhibitor during the window of implantation. We describe syndrome-associated alterations in cell-to-cell communication and gene expression profiles that support a dysfunctional pro-fibrotic, pro-inflammatory, and anti-angiogenic environment.

O-Fucosylation of BMP1 promotes endometrial decidualization by activating BMP/Smad signaling pathway

Endometrial decidualization is critical to successful uterine receptivity and embryo implantation. Dysfunction of decidualization is associated with some pregnancy-related disorders, including miscarriage. Protein glycosylation is involved in many physiological and pathological processes. Protein O-fucosyltransferase 1 (poFUT1) is a key enzyme responsible for O-fucosylation biosynthesis on glycoproteins. Bone morphogenetic protein 1 (BMP1) is an essential glycoprotein in reproduction. However, the role and molecular mechanism of fucosylated BMP1 in endometrial stromal cell decidualization are still unknown. In the current study, we found that BMP1 contains a potential O-fucosylation site. Moreover, poFUT1 and BMP1 levels in the secretory phase are higher than those in the proliferative phase, and the highest level was observed in the human uterine tissues of early pregnancy, while a decrease of poFUT1 and BMP1 in the decidua was observed in miscarriage patients. Using human endometrial stromal cells (hESCs), we demonstrated that O-fucosylation of BMP1 was elevated after induced decidualization. Moreover, the increase of BMP1 O-fucosylation by poFUT1 promoted BMP1 secretion to the extracellular matrix, and more actively binds to CHRD. The binding of BMP1 and CHRD further released BMP4 originally bound to CHRD, and activated BMP/Smad signaling pathway, thereby accelerating the decidualization of human endometrial stromal cells. In summary, these results suggest that BMP1 O-fucosylation by poFUT1 could be a potential diagnostic and therapeutic target to predict miscarriage in early pregnancy examinations.

Differentiation of human endometrial mesenchymal cells to epithelial and stromal cells by seeding on the decellularized endometrial scaffold

This study aimed to construct the endometrial-like structure by co-culturing of human mesenchymal endometrial cells and uterine smooth muscle cells in the decellularized scaffold. After decellularization of the human endometrium, cell seeding was performed by centrifugation of human mesenchymal endometrial cells with different speeds and times in 15 experimental subgroups. Analysis of residual cell count in suspension was done in all subgroups and the method with the lower number of suspended cells was selected for subsequent study. Then, the human endometrial mesenchymal cells and the myometrial muscle cells were seeded on the decellularized tissue and cultured for 1 wk; then, differentiation of the seeded cells was assessed by morphological and gene expression analysis. The cell seeding method by centrifuging at 6020 g for 2 min showed the highest number of seeded cells and the lowest number of residual cells in suspension. In the recellularized scaffold, the endometrial-like was seen with some protrusions on their surface and the stromal cells had shown spindle and polyhedral morphology. The myometrial cells almost were homed at the periphery of the scaffold and mesenchymal cells penetrated in deeper parts similar to their arrangement in the native uterus. The more expression of endometrial-related genes such as SPP1, MMP2, ZO-1, LAMA2, and COL4A1 and low-level expression of the OCT4 gene as a pluripotency marker confirmed the differentiation of seeded cells. Endometrial-like structures were formed by the co-culturing of human endometrial mesenchymal cells and smooth muscle cells on the decellularized endometrium.

Temporospatial expression of osteopontin in both left and right uterine horns during the peri-implantation period of dromedary camel

Pregnancy in camels is established and maintained predominantly in the left uterine horn (98% frequency), whereas pregnancies occurring in the right horn result in early embryonic death. Aside from other reasons such as asynchrony of conceptus signaling and uterine receptivity, this phenomenon contributes to low reproductive efficiency in camels. The current research focuses on the expression of osteopontin (OPN), an extracellular matrix protein and adhesion molecule involved in implantation in mammals. Based on the differences in the pregnancy rate between the left and right horns, the temporal and spatial OPN expression was analyzed during the peri-implantation period on Days 8, 10, and 12. Results showed that OPN expression on Day 10 significantly increased by 14.5 fold in the left and 8.4-fold in the right uterine horn. By Day 12, OPN expression increased to 39.4 fold in the left and increased 7-fold in the right horn compared with non-mated females. Only the full length, 70-kDa OPN, was detected and upregulated with advancing pregnancy, with higher intensity in the left uterine horns than in the right. Spatially, OPN was predominantly localized on the apical uterine luminal and glandular epithelium in all camels. Moreover, OPN was detected in the stratum compactum stroma of pregnant camels. In conclusion, OPN mRNA and protein were detected and upregulated during the peri-implantation period, with higher OPN expression detected in the left uterine horn than in the right. OPN may be regulated by the presence of the embryo in the left uterine horn due to its role in embryo adhesion, implantation and placentation.

Interferon-τ -induced ISG15-AS regulates endometrial receptivity during early goat pregnancy

Endometrial receptivity is a critical process for the successful establishment of pregnancy in ruminants. However, the biological role of long non-coding RNAs (lncRNAs) in the development of endometrial receptivity is poorly understood. In this study, we performed RNA-seq analysis of immortalised goat endometrial epithelial cells (gEECs) treated with interferon-τ (IFNT). Transcriptome profiles showed that 8069 high-confidence putative lncRNAs, including 6498 intronic lncRNA transcripts, 1078 lincRNAs and 493 antisense lncRNAs were identified in gEECs with or without IFNT treatment. Functional clustering analysis was performed by using cis and trans lncRNAs prediction. GO and KEGG analyses revealed that differentially expressed lncRNAs may regulate tissue remodelling and immune responses. Subsequently, six of the 21 differentially expressed antisense lncRNAs were validated using qRT-PCR. Through functional screening and co-expression analysis of lncRNAs in gEECs, we identified that ISG15-AS was mainly expressed in the luminal and glandular epithelium on days 5 and 15 and was strongly upregulated on day 18 of pregnancy in vivo. Similarly, ISG15-AS was abundant in the nucleus and cytoplasm, and was significantly upregulated after treatment with IFNT in gEECs. In addition, ISG15 is an IFNT-responsive gene, that displayed an evident increase in vivo and in vitro. Moreover, sense ISG15 was significantly upregulated following ISG15-AS silencing. The key genes related to ISGylation and endometrial receptivity in gEECs dramatically increased after ISG15-AS inhibition. Collectively, our results indicate that a novel antisense lncRNA, ISG15-AS, may be important in regulating endometrial receptivity through ISGylation.

A Comparative Review of Pregnancy and Cancer and Their Association with Endoplasmic Reticulum Aminopeptidase 1 and 2

The fundamental basis of pregnancy and cancer is to determine the fate of the survival or the death of humanity. However, the development of fetuses and tumors share many similarities and differences, making them two sides of the same coin. This review presents an overview of the similarities and differences between pregnancy and cancer. In addition, we will also discuss the critical roles that Endoplasmic Reticulum Aminopeptidase (ERAP) 1 and 2 may play in the immune system, cell migration, and angiogenesis, all of which are essential for fetal and tumor development. Even though the comprehensive understanding of ERAP2 lags that of ERAP1 due to the lack of an animal model, recent studies have shown that both enzymes are associated with an increased risk of several diseases, including pregnancy disorder pre-eclampsia (PE), recurrent miscarriages, and cancer. The exact mechanisms in both pregnancy and cancer need to be elucidated. Therefore, a deeper understanding of ERAP's role in diseases can make it a potential therapeutic target for pregnancy complications and cancer and offer greater insight into its impact on the immune system.

Interleukin-15 deficient rats have reduced osteopontin at the maternal-fetal interface

Introduction: Uterine Natural Killer (NK) cells are the predominant immune cells within the decidua during early pregnancy. These cells are thought to regulate aspects of decidualization and placental development, but their functions remain poorly characterized, especially in species with deeply invading trophoblasts such as humans and rats. Interleukin-15 (IL-15) is a cytokine required for NK cell development and survival. IL-15 mutant (IL15Δ/Δ) rats lack NK cells and exhibit altered placental development with precocious trophoblast invasion. In this study, we profiled gene expression differences between wild-type and IL15Δ/Δ implantation sites to reveal candidate factors produced by uterine NK cells that may regulate placentation and trophoblast invasion. Methods: Clariom S gene expression profiling was performed using implantation sites collected from pregnant wild-type and IL15Δ/Δ rats on gestational day 9.5. Levels and localization of perforin and osteopontin in implantation sites from wild-type and IL15Δ/Δ rats were further analyzed. The effect of osteopontin on the invasive capacity of rat trophoblasts was evaluated using Matrigel-based Transwell assays. Results: There were 257 genes differentially expressed between wild-type and IL15Δ/Δ implantation sites on gestational day 9.5, including decreased expression of various NK cell markers in IL15Δ/Δ rats, as well as Spp1, which encodes osteopontin. In wild-type rats, osteopontin was present within the decidua basalis and adjacent to the primitive placenta, and osteopontin colocalized with the NK cell marker perforin. Osteopontin was also detectable in uterine glands. Conversely, in IL15Δ/Δ rats, osteopontin and perforin were not readily detectable in the decidua despite robust osteopontin levels in uterine glands. Neutralization of osteopontin in media conditioned by cells isolated from the decidua decreased invasion of rat trophoblasts, suggesting that reduced levels of osteopontin are unlikely to account for the precocious trophoblast invasion in IL15Δ/Δ rats. Conclusion: Osteopontin is expressed by NK cells at the maternal-fetal interface in rats and may contribute to modulation of trophoblast invasion.

Intrauterine botulinum toxin A administration promotes endometrial regeneration mediated by IGFBP3-dependent OPN proteolytic cleavage in thin endometrium

Adequate endometrial growth is a critical factor for successful embryo implantation and pregnancy maintenance. We previously reported the efficacy of intrauterine administration of botulinum toxin A (BoTA) in improving the endometrial angiogenesis and the rates of embryo implantation. Here, we further evaluated its potent therapeutic effects on the uterine structural and functional repair and elucidated underlying molecular regulatory mechanisms. This study demonstrated that a murine model of thin endometrium was successfully established by displaying dramatically decreased endometrial thickness and the rates of embryo implantation compared to normal endometrium. Interestingly, the expressions of insulin-like growth factor binding protein-3 (IGFBP3) and an active 35 kDa-form of osteopontin (OPN) were significantly reduced in thin endometrium, which were almost fully restored by intrauterine BoTA administration. Neutralization of BoTA-induced IGFBP3 subsequently suppressed proteolytic cleavage of OPN, exhibiting un-recovered endometrial thickness even in the presence of BoTA administration, suggesting that BoTA-induced endometrial regeneration might be mediated by IGFBP3-dependent OPN proteolytic cleavage. Our findings suggest that intrauterine BoTA administration improves the endometrial environment in our murine model with thin endometrium by increasing endometrial receptivity and angiogenesis in a manner dependent on the regulatory effect of IGFBP3 on OPN proteolytic cleavage, proposing BoTA as an efficient therapeutic strategy for the patients with thin endometrium.

Monocytes and macrophages in pregnancy: The good, the bad, and the ugly

A successful human pregnancy requires precisely timed adaptations by the maternal immune system to support fetal growth while simultaneously protecting mother and fetus against microbial challenges. The first trimester of pregnancy is characterized by a robust increase in innate immune activity that promotes successful implantation of the blastocyst and placental development. Moreover, early pregnancy is also a state of increased vulnerability to vertically transmitted pathogens notably, human immunodeficiency virus (HIV), Zika virus (ZIKV), SARS-CoV-2, and Listeria monocytogenes. As gestation progresses, the second trimester is marked by the establishment of an immunosuppressive environment that promotes fetal tolerance and growth while preventing preterm birth, spontaneous abortion, and other gestational complications. Finally, the period leading up to labor and parturition is characterized by the reinstatement of an inflammatory milieu triggering childbirth. These dynamic waves of carefully orchestrated changes have been dubbed the "immune clock of pregnancy." Monocytes in maternal circulation and tissue-resident macrophages at the maternal-fetal interface play a critical role in this delicate balance. This review will summarize the current data describing the longitudinal changes in the phenotype and function of monocyte and macrophage populations in healthy and complicated pregnancies.

Vitamin D Supplementation Improves Uterine Receptivity in a Rat Model of Vitamin D Deficiency: A Possible Role of HOXA-10/FKBP52 Axis

Synchronized uterine receptivity with the time of implantation is crucial for pregnancy continuity. Vitamin D (VD) deficiency has been linked to the failure of implantation. Therefore, we tested the link between the Homeobox transcription factor-10/immunophilin FK506-binding protein 52 (HOXA-10/FKBP52) axis and the uterine receptivity in VD-deficient rats. The effect of VD supplementation at different doses was also investigated. Forty-eight pregnant rats were divided into six groups (eight/group); normal control rats fed with standard chow (control), control rats supplemented with VD (equivalent dose of 400 IU/day) (control-D400). VD-deficient group (DEF) and the three VD deficiency groups with VD supplementation were equivalent to 400, 4,000, and 10,000 IU/day (DEF-D400, DEF-D4000, and DEF-D10000, respectively). The expression levels of HOXA-10/FKBP52, progesterone level, and histological evaluation of decidualization using osteopontin (OSN) and progesterone receptor (PGR) were estimated. An assessment of the uterine contractility was conducted for all rats. This study showed the downregulation of HOXA-10/FKBP52 together with increased amplitude and frequency of the uterine contractility in the DEF group compared to control. VD dose-dependent supplementation restored progesterone/receptor competency, upregulated the expressional response of HOXA-10 and its downstream FKBP52, and improved uterine receptivity and endometrial decidualization at the time of implantation that was documented by increased area% of OSN and the number of implantation beads.

Osteopontin as a Regulator of Colorectal Cancer Progression and Its Clinical Applications

Simple Summary

The mortality of colorectal cancer is principally related to metastatic disease at the time of diagnosis or to the growth of initially undetectable micro-metastasis. Current therapeutic strategies are efficient in patients with locally advanced cancer, but are rarely able to cure patients with metastatic disease. Therapeutic failure is mainly associated with drug resistance and an aggressive phenotype. The identification of new biomarkers for micro-metastasis and tumor progression remains an unmet clinical need that should allow for improved patient stratification for optimal treatment and may lead to the identification of novel therapeutic targets. Osteopontin (OPN), a multifunctional protein, has emerged as a potentially valuable biomarker in several cancer types. This review principally describes the molecular mechanisms of OPN that are associated with colorectal cancer (CRC) progression and metastasis, as well as the use of OPN as a clinical biomarker. This review identifies a role for OPN as a biomarker ready for extended clinical application and discusses its use as a therapeutic target.

Abstract

A high expression of the phosphoprotein osteopontin (OPN) has been associated with cancer progression in several tumor types, including breast cancer, hepatocarcinoma, ovarian cancer, and colorectal cancer (CRC). Interestingly, OPN is overexpressed in CRC and is associated with a poor prognosis linked to invasion and metastasis. Here, we review the regulation and functions of OPN with an emphasis on CRC. We examine how epigenetic and genetic regulators interact with the key signaling pathways involved in this disease. Then, we describe the role of OPN in cancer progression, including proliferation, survival, migration, invasion, and angiogenesis. Furthermore, we outline the interest of using OPN as a clinical biomarker, and discuss if and how osteopontin can be implemented as a routine assay in clinical laboratories for monitoring CRC patients. Finally, we discuss the use of OPN an attractive, but challenging, therapeutic target.

Steroid regulation of secreted phosphoprotein 1 (SPP1) expression in ovine endometrium

Secreted phosphoprotein 1 (SPP1) is an extracellular matrix glycoprotein that is highly expressed at the maternal-fetal interface and is a critical mediator of embryo implantation. The objectives of this study were to examine the spatial and temporal cyclical expression patterns and steroid regulation of SPP1 mRNA and protein in ovine endometrium, which may be further indicative of their functionality in embryo implantation. Uterine tissue was obtained following hysterectomy from ovariectomised ewes treated with ovarian steroids. In parallel, invitro culture of endometrial cells was used to investigate the effects of ovarian steroids on SPP1 expression in endometrial and luminal epithelial (LE) cells. A significant sustained mid-luteal phase increase in SPP1 mRNA in intercaruncular regions of the endometrium was observed, indicating that glandular epithelium is likely to be the primary source of SPP1 production. This increase in SPP1 was induced by progesterone treatment and was shown at the protein level by immunohistochemistry analysis. Similarly, treatment of stromal cells with 10ng mL-1 progesterone or in combination with 1ng mL-1 oestradiol significantly increased SPP1 expression (P<0.05). Collectively, expression levels of SPP1 are cycle-dependent and peak in the progesterone-dominant luteal phase. They are dependent on the interaction of uterine LE and stromal cells and may involve paracrine signalling by progesterone receptor-positive stromal cells.

Epigenetic modifications working in the decidualization and endometrial receptivity

Decidualization is a critical event for the blastocyst implantation, placental development and fetal growth and the normal term. In mice, the embryo implantation to the uterine epithelial would trigger the endometrial stromal cells to differentiate into decidual stromal cells. However, decidualization in women takes place from the secretory phase of each menstrual cycle and continues to early pregnancy if there is conceptus. Deficient decidualization is often associated with pregnancy specific complications and reproductive disorders. Dramatic changes occur in the gene expression profiles during decidualization, which is coordinately regulated by steroid hormones, growth factors, and molecular and epigenetic mechanisms. Recently, emerging evidences showed that epigenetic modifications, mainly including DNA methylation, histone modification, and non-coding RNAs, play an important role in the decidualization process via affecting the target genes' expression. In this review, we will focus on the epigenetic modifications in decidualization and open novel avenues to predict and treat the pregnancy complications caused by abnormal decidualization.