Gestational age-dependent extravillous cytotrophoblast osteopontin immunolocalization differentiates between normal and preeclamptic pregnancies

Bioinformatic Analysis Identifies Potential Extracellular Matrix Related Genes in the Pathogenesis of Early Onset Preeclampsia

Early-onset preeclampsia (EOPE) is a complex pregnancy complication that poses significant risks to the health of both mothers and fetuses, and research on its pathogenesis and pathophysiology remains insuffcient. This study aims to explore the role of candidate genes and their potential interaction mechanisms in EOPE through bioinformatics analysis techniques. Two gene expression datasets, GSE44711 and GSE74341, were obtained from the Gene Expression Omnibus (GEO) to identify differentially expressed genes (DEGs) between EOPE and gestational age-matched preterm control samples. Functional enrichment analysis was performed utilizing the kyoto encyclopedia of genes and genomes (KEGG), gene ontology (GO), and gene set enrichment analysis (GSEA). A protein-protein interaction (PPI) network was constructed using the STRING database, and hub DEGs were identified through Cytoscape software and comparative toxicogenomics database (CTD) analysis. Furthermore, a diagnostic logistic model was established using these hub genes, which were confirmed through reverse transcription polymerase chain reaction (RT-PCR). Finally, immune cell infiltration was analyzed using CIBERSORT. In total, 807 DEGs were identified in the GSE44711 dataset (451 upregulated genes and 356 downregulated genes), and 787 DEGs were identified in the GSE74341 dataset (446 upregulated genes and 341 downregulated genes). These DEGs were significantly enriched in various molecular functions such as extracellular matrix structural constituent, receptor-ligand activity binding, cytokine activity, and platelet-derived growth factor. KEGG and GSEA annotation revealed significant enrichment in pathways related to ECM-receptor interaction, PI3K-AKT signaling, and focal adhesion. Ten hub genes were identified through the CytoHubba plugin in Cytoscape. Among these hub genes, three key DEGs (COL1A1, SPP1, and THY1) were selected using CTD analysis and various topological methods in Cytoscape. The diagnostic logistic model based on these three genes exhibited high efficiency in predicting EOPE (AUC = 0.922). RT-PCR analysis confirmed the downregulation of these genes in EOPE, and immune cell infiltration analysis suggested the significant role of M1 and M2 macrophages in EOPE. In conclusion, this study highlights the association of three key genes (COL1A1, SPP1, and THY1) with EOPE and their contribution to high diagnostic efficiency in the logistic model. Additionally, it provides new insights for future research on EOPE and emphasizes the diagnostic value of these identified genes. More research is needed to explore their functional and diagnostic significance in EOPE.

Role of osteopontin (OPN) in uterine spiral artery remodeling

Uterine spiral artery (SpA) remodeling is critical for a successful pregnancy. The deficiency of SpA remodeling seriously affects the blood perfusion of the placenta, impacting the nutritional supply to the fetus and therefore fetal growth and development, which is one of the pathological causes of pregnancy related diseases. This process involves the interaction between all cells and related factors at the maternal-fetal interface, especially extravillous trophoblast cells (EVT), vascular smooth muscle cells (VSMCs) and decidual immune cells. Osteopontin (OPN), as a glycosylated protein, is widely localized in the extracellular matrix and participates in a variety of cellular activities such as migration, adhesion, differentiation and survival. OPN plays an important role in placental development, uterine decidualization and pregnancy success. This study focuses on the role of OPN in uterine spiral artery remodeling and its related molecular mechanism.

Integrated microarray analysis of key genes and a miRNA‑mRNA regulatory network of early‑onset preeclampsia

Early‑onset preeclampsia (EOPE) is a serious threat to maternal and foetal health. The present study aimed to identify potential biomarkers and targets for the treatment of EOPE. Expression profiles of placenta from patients with EOPE and healthy controls (GSE103542, GSE74341 and GSE44711) were downloaded from the Gene Expression Omnibus database. Integrated analysis revealed 246 genes and 28 microRNAs (miRNAs) that were differentially expressed between patients with EOPE and healthy controls. Differentially expressed genes (DEGs) were primarily enriched in 'biological processes', such as 'cell adhesion', 'female pregnancy', 'extracellular matrix organization' and 'response to hypoxia'. Significant pathways associated with DEGs primarily included 'focal adhesion', 'ECM‑receptor interaction', 'PI3K‑Akt signaling' and 'ovarian steroidogenesis'. A Protein‑Protein Interaction network of DEGs was constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins online database, and epidermal growth factor receptor, collagen α‑1(I) chain, secreted phosphoprotein 1, leptin (LEP), collagen α‑2(I) chain (COL1A2), plasminogen activator inhibitor 1 (SERPINE1), Thy‑1 membrane glycoprotein, bone morphogenetic protein 4, vascular cell adhesion protein 1 and matrix metallopeptidase 1 were identified as hub genes. The alterations of hsa‑miR‑937, hsa‑miR‑148b*, hsa‑miR‑3907, hsa‑miR‑367*, COL1A2, LEP and SERPINE1 in placenta were validated using our local samples. Our research showed that the expression of hsa‑miR‑937, hsa‑miR‑1486*, hsa‑miR‑3907, hsa‑miR‑367* and hub genes in the placenta were closely associated with the pathophysiology of EOPE. hsa‑miR‑937, hsa‑miR‑1486*, hsa‑miR‑3907, hsa‑miR‑367* and hub genes could serve as biomarkers for diagnosis and as potential targets for the treatment of EOPE.

Identification of Key Genes and Long Noncoding RNA-Associated Competing Endogenous RNA (ceRNA) Networks in Early-Onset Preeclampsia

Background

Preeclampsia (PE) is a pregnancy-specific hypertension syndrome and is one of the leading causes of maternal and perinatal morbidity and mortality. Long noncoding RNAs (lncRNAs) have been reported to be abnormally expressed in many diseases, including preeclampsia. The present study is aimed at identifying the key genes and lncRNA-associated competing endogenous RNA (ceRNA) networks in early-onset preeclampsia (EOPE).

Methods

We investigated expression profiles of differentially expressed lncRNAs (DElncRNAs) and genes (DEGs) in placental tissues of EOPE and healthy controls with Human LncRNA Array v4. The potential functions of DEGs and DElncRNAs were predicted using the clusterProfiler package. The lncRNA-mRNA coexpression network was constructed via Pearson's correlation coefficient. The protein-protein interaction (PPI) network of DEGs was constructed, and the hub genes were obtained using the STRING database and Cytoscape. The ceRNA networks were constructed based on miRWalk and LncBase v2. qRT-PCR was performed to confirm the expression of lncRNA MIR193BHG, PROX1-AS1, and GATA3-AS1. ROC curves were performed to assess the clinical value of lncRNA MIR193BHG, PROX1-AS1, and GATA3-AS1 in the diagnosis of EOPE.

Results

We found 6 hub genes (SPP1, CCR2, KIT, ENG, ACKR1, and FLT1) altered in placental tissues of EOPE and constructed a ceRNA network, including 21 lncRNAs, 3 mRNAs, and 69 miRNAs. The expression of lncRNA MIR193BHG and GATA3-AS1 were elevated and showed good clinical values for diagnosing EOPE.

Conclusion

This study provides novel insights into the lncRNA-related ceRNA network in EOPE and identified two lncRNAs as potential prognostic biomarkers in EOPE.

Integrin α8 Is Abundant in Human, Rat, and Mouse Trophoblasts

OBJECTIVE

Integrins exert regulatory functions in placentogenesis. Null mutation of certain integrin α subunits leads to placental defects with subsequent fetal growth restriction or embryonic lethality in mice. So far, the placental role of α8 integrin remains to be determined.

METHODS

Localization of α8 integrin and its ligands, fibronectin (FN) and osteopontin (OPN), was studied by immunohistochemistry in human, rat, and mouse placenta. The vascularization of the placental labyrinth layer of α8 integrin-deficient mice was determined by CD31 staining. In humans, α8 integrin expression was assessed via real-time polymerase chain reaction in healthy placentas, in the placental pathologies such as intrauterine growth restriction (IUGR), preeclampsia, and HELLP-syndrome (hemolysis, elevated liver enzymes, low platelet count), as well as in primary extravillous trophoblasts (EVT) and villous trophoblasts.

RESULTS

In humans, α8 integrin was detected in first and third trimester syncytiotrophoblast and EVT. Although OPN showed the same localization, FN was observed in EVT only. No expressional changes in α8 integrin were detected in the placental pathologies studied. Rodent placenta showed α8 integrin expression in giant cells and in the labyrinth layer. The localization of OPN and FN, however, showed species-specific differences. Knockout of α8 integrin in mice did not cause IUGR, despite some reduction in labyrinth layer vascularization.

CONCLUSION

α8 Integrin is expressed in functional placental compartments among its ligands, OPN and/or FN, across species. Although this may point to a regulatory role in trophoblast function, our data from α8 integrin-deficient mice indicated only mild placental pathology. Thus, the lack of placental α8 integrin seems to be largely compensated for.

IFN-γ inhibits osteopontin expression in human decidual stromal cells and can be attenuated by 1α,25-dihydroxyvitamin D3

PROBLEM

The effect of IFN-γ on the expression of osteopontin (OPN), in the presence or absence of 1α,25-dihydroxyvitamin D3 (1,25(OH)(2) D(3) ), in decidual stromal cells (DSC).

METHOD OF STUDY

Decidual stromal cells were isolated from women undergoing elective termination of pregnancy (gestational age, 6-9 weeks). After characterization, they were treated with IFN-γ in the presence or absence of 1,25(OH)(2) D(3) . The uterus of pregnancy IFN-γ knockout mice were collected on gestation day (gd) 7.5, and the expression of OPN were examined.

RESULTS

IFN-γ drastically decreased the expression of OPN in DSC, which was reverted by the addition of 1,25(OH)(2) D(3) to the IFN-γ-treated decidual cells. Moreover, the OPN expression in uterus of IFN-γ knockout mice was higher than that of wild-type counterparts.

CONCLUSIONS

We demonstrated OPN was expressed in DSC in human first-trimester decidua and in the uterus in mice at 7.5 gd. The OPN expression was closely correlated with regulation of IFN-γ and 1,25(OH)(2) D(3) in human early pregnancy. OPN expression in DSC was significantly decreased with the treatment of IFN-γ. 1,25(OH)(2) D(3) played an opposite role in IFN-γ-mediated inhibition of OPN expression in human DSC.

Plasma osteopontin concentrations in preeclampsia - is there an association with endothelial injury?

Abstract Background: It has been previously reported that plasma osteopontin (OPN) concentrations are increased in cardiovascular disorders. The goal of the present study was to determine plasma OPN concentrations in healthy pregnant women and preeclamptic patients, and to investigate their relationship to the clinical characteristics of the study subjects and to markers of inflammation [C-reactive protein (CRP)], endothelial activation [von Willebrand factor antigen (VWF:Ag)] or endothelial injury (fibronectin), oxidative stress [malondialdehyde (MDA)] and trophoblast debris (cell-free fetal DNA).

METHODS

Forty-four patients with preeclampsia and 44 healthy pregnant women matched for age and gestational age were involved in this case-control study. Plasma OPN concentrations were measured with ELISA. Serum CRP concentrations were determined with an autoanalyzer using the manufacturer's reagents. Plasma VWF:Ag was quantified by ELISA, while plasma fibronectin concentrations were measured by nephelometry. Plasma MDA concentrations were estimated by the thiobarbituric acid-based colorimetric assay. The amount of cell-free fetal DNA in maternal plasma was determined by quantitative real-time PCR analysis of the sex-determining region Y (SRY) gene. For statistical analyses, non-parametric methods were applied.

RESULTS

Serum levels of CRP, as well as plasma concentrations of VWF:Ag, fibronectin, MDA and cell-free fetal DNA were significantly higher in preeclamptic patients than in healthy pregnant women. There was no significant difference in plasma OPN concentrations between controls and the preeclamptic group. However, preeclamptic patients with plasma fibronectin concentrations in the upper quartile had significantly higher plasma OPN concentrations than those below the 75th percentile, as well as healthy pregnant women [median (interquartile range): 9.38 (8.10-11.99) vs. 7.54 (6.31-9.40) and 7.40 (6.51-8.80) ng/mL, respectively, p<0.05 for both]. Furthermore, in preeclamptic patients, plasma OPN concentrations showed a significant positive linear association with plasma fibronectin (Spearman R=0.38, standardized regression coefficient (beta)=0.41, p<0.05 for both).

CONCLUSIONS

Plasma OPN concentrations are increased in preeclamptic patients with extensive endothelial injury. However, further studies are warranted to explore the relationship between OPN and endothelial damage. Clin Chem Lab Med 2010;48:181-7.

The immunohistochemical expression profile of osteopontin in normal human tissues using two site-specific antibodies reveals a wide distribution of positive cells and extensive expression in the central and peripheral nervous systems

To elucidate the cellular distribution of osteopontin (OPN) in normal human tissues, we undertook immunohistochemistry using two site-specific OPN antibodies. The 10A16 monoclonal antibody was raised against the amino acid sequence just downstream of the thrombin cleavage site, while the O-17 polyclonal antibody was raised against the N-terminal peptide. Each antibody has been confirmed previously to react with both whole OPN and its relevant fragments. The expression pattern for these two antibodies was similar in distribution. In addition, we also identified expression in Ebner's gland, type II pneumocytes, Kupffer cells, cells of the endocrine organs, anterior lens capsule and ciliary body, synovial type A cells, mesothelia, adipocytes, and mast cells. Neurons and glia in the central nervous system and spinal cord, cranial and peripheral nerve sheaths, ganglion cells in the sympathetic ganglion, intestinal plexuses, retina, and choroid plexus also regularly exhibited OPN positivity. Testicular germ cells, pancreatic exocrine cells, and follicular dendritic cells reacted with 10A16 only, whereas lutein cells and taste bud cells exhibited O-17 reactivity alone. These minor differences were hypothesized to reflect the state of OPN in the cells; that is, whether OPN was in its whole molecule or fragmented form. In conclusion, we demonstrate that OPN is widely distributed in normal human cells, particularly those comprising the central and peripheral nervous systems.

Gene expression profiling of human decidual macrophages: evidence for immunosuppressive phenotype

Background

Although uterine macrophages are thought to play an important regulatory role at the maternal-fetal interface, their global gene expression profile is not known.

Methodology/Principal Findings

Using micro-array comprising approximately 14,000 genes, the gene expression pattern of human first trimester decidual CD14+ monocytes/macrophages was characterized and compared with the expression profile of the corresponding cells in blood. Some of the key findings were confirmed by real time PCR or by secreted protein. A unique gene expression pattern intrinsic of first trimester decidual CD14+ cells was demonstrated. A large number of regulated genes were functionally related to immunomodulation and tissue remodelling, corroborating polarization patterns of differentiated macrophages mainly of the alternatively activated M2 phenotype. These include known M2 markers such as CCL-18, CD209, insulin-like growth factor (IGF)-1, mannose receptor c type (MRC)-1 and fibronectin-1. Further, the selective up-regulation of triggering receptor expressed on myeloid cells (TREM)-2, alpha-2-macroglobulin (A2M) and prostaglandin D2 synthase (PGDS) provides new insights into the regulatory function of decidual macrophages in pregnancy that may have implications in pregnancy complications.

Conclusions/Significance

The molecular characterization of decidual macrophages presents a unique transcriptional profile replete with important components for fetal immunoprotection and provides several clues for further studies of these cells.

Searching for genetic clues to the causes of pre-eclampsia

Pre-eclampsia and its related syndromes are significant causes of maternal and fetal death, but much remains unclear about the underlying disease mechanisms. Epidemiological research has consistently demonstrated a familial predisposition to pre-eclampsia, which has encouraged genetic research in this area. The goal is the discovery of susceptibility genes which will inform understanding of the pathophysiology of pre-eclampsia, and may prove to be targets for therapeutic or preventative strategies. This review examines the application of molecular technologies to the search for genetic clues in pre-eclampsia and emphasizes the importance of integrative approaches. The results of recent genome-wide linkage studies have been particularly encouraging, identifying a number of loci which merit closer examination. Candidate gene studies have proved less fruitful, generating conflicting and inconclusive results. Possible explanations and remedies for this deficiency are discussed with a view to stimulating closer collaboration between researchers in this field.

Osteopontin Expression in Gestational Trophoblastic Diseases: Correlation With Expression of the Adhesion Molecule, CEACAM1

The human placenta is a complex tissue with multiple endocrine and nutritional functions and a unique capacity for rapid proliferation but tightly controlled invasion, differentiating it from malignant tumors. Osteopontin (OPN) is a glycoprotein of the extracellular matrix, which has been shown to mediate cellular migration and invasion and to contribute to tumorigenesis in several types of cancers. OPN also could be implicated in regulating implantation and placentation by promoting cellular migration and invasion in a placenta-specific fashion. We could demonstrate the expression pattern of OPN in the normal human placenta in which it is localized in the extravillous (intermediate) trophoblast and the villous cytotrophoblast. CEACAM1 is an adhesion molecule, which we have recently found to be expressed at the maternal-fetal interface of the normal placenta with a localization to the extravillous (invasive) trophoblast and in gestational trophoblastic disease (GTD) and also to be potentially implicated in trophoblast invasion and tumorigenesis. Both OPN and CEACAM1 have been shown to interact with integrin beta3. The purpose of this study was to investigate the expression pattern of OPN in GTD and to correlate it with the expression of CEACAM1. To analyze the expression of OPN, we performed immunohistochemistry on a total of 27 cases of GTD, including 21 hydatidiform moles and 6 choriocarcinomas, which had previously been characterized with respect to their CEACAM1 expression. Hydatidiform moles showed a positivity for OPN in villous cytotrophoblast and in the trophoblast proliferations on the villous surface. The strongest OPN expression could be observed in the choriocarcinomas with a heterogenous OPN expression pattern. CEACAM1 had shown similar results and was found to be expressed in choriocarcinoma. The expression pattern of osteopontin in gestational trophoblastic diseases indicates that it might play a role in the pathogenesis of GTD (possibly as a functional complex with CEACAM1 and integrin beta3) and might be useful as an additional diagnostic marker for such lesions.

Prenatal detection of embryo resorption in osteopontin-deficient mice using serial noninvasive magnetic resonance microscopy

Appropriate temporal and spatial expression of osteopontin (OPN) in the female genital tract may be critical for successful embryo implantation and maintenance of gestation. Traditionally, experimental assessments of reproductive success have been limited to ex vivo dissection at a single time point to determine embryo number and size and are inadequate for ongoing study of the effect(s) of genetic manipulation on any individual gestation. To investigate the role of OPN in the maintenance of gestation, we developed a noninvasive, in vivo method of pregnancy surveillance suitable for murine application using magnetic resonance microscopy (MRM). Gravid wild-type mice (n =7) and mice with targeted disruption of one or both OPN alleles (OPN(-/-), n = 9; OPN(+/-), n = 3) underwent MRM on postcoital days 10.5, 15.5, and 19.5. Prenatal MRM images were used to determine embryo numbers and sizes. There were no significant differences in embryo numbers determined independently by two blinded observers (mean difference between observers = 0.04 embryos; p = 0.87). There was a significant effect of genotype on embryo size, with OPN(-/-) embryos significantly smaller at all gestational ages. However, targeted disruption of one or more OPN alleles had no effect on embryo number at any gestational age. Thus, MRM may be a powerful noninvasive method for in vivo prenatal developmental study of genetically engineered mice.

Healthy and pre-eclamptic placental basal plate lining cells: Quantitative comparisons based on confocal laser scanning microscopy

Immunocytochemical confocal laser scanning microscope images of the monolayer of cells lining the intervillus space at the basal plate of term placentae were analysed using stereology. Immunoreactively-distinct regions of this mosaic layer were measured. In basal plate from healthy pregnancies, trophoblast epithelium occupied 18.91% of the surface area and endothelium 60.81%. In pre-eclampsia the equivalent areas were 15.57% and 67.63%. Acellular fibrinoid covers the remaining area and this component decreases in area in pre-eclampsia. The statistically significant increase in the cellular endothelial compartment may be relevant to the hypertensive pathology of pre-eclampsia as endothelial signalling plays a major role in regulation of blood pressure.

Osteopontin deficiency in rat vascular smooth muscle cells is associated with an inability to adhere to collagen and increased apoptosis

Osteopontin (OPN) is an extracellular matrix protein that has been implicated in vascular smooth muscle cell (VSMC) adhesion. We have previously described the generation of OPN-deficient VSMC that displayed altered adhesion to collagen. We have examined further the causes and consequences of this altered adhesion. OPN-deficiency was associated with a significant reduction in surface expression of alpha1 and beta1 integrins (mean fluorescence intensity alpha1: OPN-deficient 0.135+/-0.04 vs. control 0.313+/-0.05, p < 0.0001; beta1: OPN-deficient 0.398+/-0.09 vs. control 0.570+/-0.05, p < 0.004). Treatment of normal VSMC with antibody to alpha1 recapitulated the adhesion defect. OPN-deficient cells without collagen exposure had an apoptotic fraction of 1.9%, which increased to 95.7% after 24 hours exposure to collagen. Exogenous OPN added to cultures within 15 minutes of plating restored normal cell adhesion, but did not prevent cells from undergoing apoptosis. Normal VSMC had no detectable apoptosis after 24 hours incubation in suspension, whereas OPN-deficient cells had an apoptotic fraction of 37.5% when incubated in suspension under the same conditions. The data suggest that OPN-deficient VSMC have two distinct abnormalities: an alpha1beta1-mediated inability to adhere normally to collagen and an increased propensity for apoptosis.