Decreased Expression of Placental Proteins in Recurrent Pregnancy Loss: Functional Relevance and Diagnostic Value

Miscarriages affect 50-70% of all conceptions and 15-20% of clinically recognized pregnancies. Recurrent pregnancy loss (RPL, ≥2 miscarriages) affects 1-5% of recognized pregnancies. Nevertheless, our knowledge about the etiologies and pathophysiology of RPL is incomplete, and thus, reliable diagnostic/preventive tools are not yet available. Here, we aimed to define the diagnostic value of three placental proteins for RPL: human chorionic gonadotropin free beta-subunit (free-β-hCG), pregnancy-associated plasma protein-A (PAPP-A), and placental growth factor (PlGF). Blood samples were collected from women with RPL (n = 14) and controls undergoing elective termination of pregnancy (n = 30) at the time of surgery. Maternal serum protein concentrations were measured by BRAHMS KRYPTOR Analyzer. Daily multiple of median (dMoM) values were calculated for gestational age-specific normalization. To obtain classifiers, logistic regression analysis was performed, and ROC curves were calculated. There were differences in changes of maternal serum protein concentrations with advancing healthy gestation. Between 6 and 13 weeks, women with RPL had lower concentrations and dMoMs of free β-hCG, PAPP-A, and PlGF than controls. PAPP-A dMoM had the best discriminative properties (AUC = 0.880). Between 9 and 13 weeks, discriminative properties of all protein dMoMs were excellent (free β-hCG: AUC = 0.975; PAPP-A: AUC = 0.998; PlGF: AUC = 0.924). In conclusion, free-β-hCG and PAPP-A are valuable biomarkers for RPL, especially between 9 and 13 weeks. Their decreased concentrations indicate the deterioration of placental functions, while lower PlGF levels indicate problems with placental angiogenesis after 9 weeks.

Exposure to di-isononyl phthalate during early pregnancy disrupts decidual angiogenesis and placental development in mice

Di-isononyl phthalate (DiNP), an endocrine-disrupting chemical, is found in numerous consumer products and human exposure to this phthalate is becoming inevitable. The impact of DiNP exposure on the establishment and maintenance of pregnancy remains largely unknown. Thus, we conducted studies in which pregnant mice were exposed to an environmentally relevant dose (20 µg/kg BW/day) of DiNP on days 1-7 of gestation, then analyzed the effects of this exposure on pregnancy outcome. Our studies revealed that exposure to DiNP during this window led to fetal loss towards the end of gestation. Further studies showed that, although embryos were able to attach to the uterus, implantation sites in DiNP-exposed uteri exhibited impaired differentiation of stromal cells to decidual cells and an underdeveloped angiogenic network in the decidual bed. We also found that exposure to this phthalate has a significant effect on trophoblast differentiation and causes disorganization of the placental layers. The labyrinth was significantly reduced, resulting in compromised expression of nutrient transporters in the placentas of mice exposed to DiNP. These placental defects in DiNP-exposed females were the cause of fetal loss during the later stages of gestation.

A physiological concentration of anandamide promotes the migration of human endometrial fibroblast and the interaction with endothelial cells invitro

INTRODUCTION

The mechanisms that govern fibroblast behavior during the vascular adaptations of the uterus at early pregnancy remain unknown. Anandamide, an endocannabinoid, binds to cannabinoid receptors (CBs), and regulates gestation and angiogenesis. Its tone is regulated by fatty acid amide hydrolase (FAAH) within the uterus. We investigated the role of anandamide in endometrial fibroblasts migration and whether anandamide modulates fibroblasts-endothelial crosstalk.

METHODS

T-hESC and EA.hy926 cell lines were used as models of endometrial stromal and endothelial cells, respectively. T-hESC were incubated with anandamide plus different agents. Migration was tested (wound healing assay and phalloidin staining). Protein expression and localization were studied by Western blot and immunofluorescence. To test fibroblast-endothelial crosstalk, EA.hy926 cells were incubated with fibroblast conditioned media obtained after T-hESC migration.

RESULTS

Anandamide 1 nM increased T-hESC migration via CB1 and CB2. Cyclooxygenase-2 participated in anandamide-stimulated fibroblast migration. Prostaglandin F2alpha, and not prostaglandin E2, increased fibroblast wound closure. CB1, CB2, cyclooxygenase-2 and FAAH were expressed in T-hESC. Anandamide did not alter cyclooxygenase-2 localization but induced its cytoplasmic and nuclear expression through CB1 and CB2. URB-597, a FAAH selective inhibitor, also increased T-hESC migration via both CBs, and augmented cyclooxygenase-2 expression. Conditioned media from anandamide-induced T-hESC wound healing closure stimulated endothelial migration and did not alter their proliferation. Soluble factors from cyclooxygenase-2 were secreted by T-hESC and participated in T-hESC-induced EA.hy926 migration. Although anandamide-conditioned media augmented in EA.hy926 the expression of γH2AX, a marker of DNA damage, cyclooxygenase-2 was not involved in this effect.

DISCUSSION

Our results provide novel evidence about an active role of anandamide on endometrial fibroblast behavior as a mechanism regulating uterine vascular adaptations in early gestation.

PlGF/FLT-1 deficiency leads to reduced STAT3-C/EBPβ signaling and aberrant polarization in decidual macrophages during early spontaneous abortion

Introduction

Dysregulated macrophage polarization (excessive M1-like or limited M2-like macrophages) in the early decidua contributes to allogeneic fetal rejection and thus early spontaneous abortion. However, the modulators of M1/M2 balance at the early maternal-fetal interface remain mostly unknown.

Methods

First-trimester decidual tissues were collected from normal pregnant women undergoing elective pregnancy terminations and patients with spontaneous abortion. We measured the expression of placental growth factor (PlGF) and Fms-like-tyrosine-kinase receptor 1 (FLT-1), and characterized the profiles of macrophages in decidua. Notably, we investigated the effect of recombinant human PlGF (rhPlGF) on decidual macrophages (dMös) from normal pregnancy and revealed the underlying mechanisms both in vitro and in vivo.

Results

The downregulated expression of PlGF/ FLT-1 may result in spontaneous abortion by inducing the M1-like deviation of macrophages in human early decidua. Moreover, the CBA/J×DBA/2 abortion-prone mice displayed a lower FLT-1 expression in uterine macrophages than did CBA/J×BALB/c control pregnant mice. In in vitro models, rhPlGF treatment was found to drive the M2-like polarization of dMös via the STAT3/CEBPB signaling pathway. These findings were further supported by a higher embryo resorption rate and uterine macrophage dysfunction in Pgf knockout mice, in addition to the reduced STAT3 transcription and C/EBPâ expression in uterine macrophages.

Discussion

PlGF plays a key role in early pregnancy maintenance by skewing dMös toward an M2-like phenotype via the FLT-1-STAT3-C/EBP â signaling pathway. Excitingly, our results highlight a rationale that PlGF is a promising target to prevent early spontaneous abortion.

Integrative analysis of circulating microRNAs and the placental transcriptome in recurrent pregnancy loss

Recurrent pregnancy loss (RPL) is a major type of pathological pregnancy that still lacks reliable early diagnosis and effective treatment. The placenta is critical to fetal development and pregnancy success because it participates in critical processes such as early embryo implantation, vascular remodeling, and immunological tolerance. RPL is associated with abnormalities in the biological behavior of placental villous trophoblasts, resulting in aberrant placental function. MicroRNAs (miRNAs) are increasingly being recognized as essential regulators of placental development, as well as potential biomarkers. In this study, plasma miRNAs and placental messenger RNAs (mRNAs) from RPL patients and normal pregnant (NP) controls were sequenced and analyzed. Compared to those in NP controls, 108 circulating miRNAs and 1199 placental mRNAs were differentially expressed in RPL samples. A total of 140 overlapping genes (overlapping between plasma miRNA target genes and actual placental disorder genes) were identified, and functional enrichment analysis showed that these genes were mainly related to cell proliferation, angiogenesis, and cell migration. The regulatory network among miRNAs, overlapping genes, and downstream biological processes was analyzed by protein–protein interactions and Cytoscape. Moreover, enriched mRNAs, which were predictive targets of the differentially expressed plasma miRNAs miR-766-5p, miR-1285-3p, and miR-520a-3p, were accordingly altered in the placenta. These results suggest that circulating miRNAs may be involved in the pathogenesis of RPL and are potential noninvasive biomarkers for RPL.

Human Platelet-Rich Plasma Facilitates Angiogenesis to Restore Impaired Uterine Environments with Asherman’s Syndrome for Embryo Implantation and Following Pregnancy in Mice

Asherman’s syndrome (AS) is caused by intrauterine adhesions and inactive endometrium from repeated curettage of the uterine endometrium. AS is a major cause of recurrent implantation failure and miscarriage and is very difficult to treat because of the poor recovery of endometrial basal cells. Platelet-rich plasma (PRP) has abundant growth factors that may induce angiogenesis and cell proliferation. Here, we demonstrate that human PRP (hPRP) significantly enhances angiogenesis to restore embryo implantation, leading to successful pregnancy in mice with AS. In mice with AS, hPRP treatment considerably reduced the expression of fibrosis markers and alleviated oligo/amenorrhea phenotypes. Mice with AS did not produce any pups, but the hPRP therapy restored their infertility. AS-induced abnormalities, such as aberrantly delayed embryo implantation and intrauterine growth retardation, were considerably eliminated by hPRP. Furthermore, hPRP significantly promoted not only the elevation of various angiogenic factors, but also the migration of endometrial stromal cells. It also increased the phosphorylation of STAT3, a critical mediator of wound healing, and the expression of tissue remodeling genes in a fibrotic uterus. PRP could be a promising therapeutic strategy to promote angiogenesis and reduce fibrosis in impaired uterine environments, leading to successful embryo implantation for better clinical outcomes in patients with AS.

The fate of human SUSD2+ endometrial mesenchymal stem cells during decidualization

Regeneration of the endometrial stromal compartment in premenopausal women is likely maintained by the perivascular endometrial mesenchymal stem/stromal cells (eMSC) expressing sushi domain containing 2 (SUSD2). The fate of SUSD2+ eMSC during pregnancy and their role in decidualization is not fully known. The aim of our study was to determine the effect of progesterone on the stemness of the SUSD2+ eMSC isolated from non-pregnant uterine samples. Secondary objectives were to characterize the functional capacity including differentiation and clonogenicity assays of SUSD2+ eMSC isolated from decidua at full term and compare it to the capacity of those isolated from non-pregnant uterine samples. Progesterone treatment induced changes in the decidual gene expression profile in non-pregnant SUSD2+ eMSC. Data analysis of a publicly available single cell RNA-seq data set revealed differential expression of several mesenchymal and epithelial signature genes between the SUSD2+ eMSC and the decidual stromal cells, suggesting mesenchymal-to-epithelial transition occurs during decidualization. Histological analysis revealed a significantly lower abundance of SUSD2+ eMSC in 1st trimester and full term samples compared to non-pregnant samples, p = 0.0296 and 0.005, respectively. The differentiation and the colony forming capacity did not differ significantly between the cells isolated from non-pregnant and pregnant uterine samples. Our results suggest that SUSD2+ eMSC undergo decidualization in vitro, while maintaining MSC plasma membrane phenotype. Human eMSC seem to play an important role in the course of endometrial decidualization and embryo implantation. Pregnancy reduced the abundance of SUSD2+ eMSC, however eMSC function remains intact.

Polymorphisms of vascular endothelial growth factor and recurrent implantation failure: a systematic review and meta-analysis

PURPOSE

To investigate the associations between polymorphisms of vascular endothelial growth factor (VEGF) with recurrent implantation failure (RIF).

METHODS

We performed the systematic review and meta-analysis by searching databases of PubMed, EMBASE, OVID, and CNKI (China National Knowledge Infrastructure) for studies that evaluated the associations between VEGF polymorphisms with RIF. Meta-analysis was performed if the polymorphism was studied by more than two case-control studies. Data were analyzed using R software. Odds ratios (ORs) with 95% confidence intervals (CIs) were reported to assess the associations.

RESULTS

Nine VEGF polymorphisms (-1154G > A, -460T > C, +405G > C, -7C > T, -634C > G, -2578C > A, +936C > T, 5C > T, -583C > T) were systematically reviewed. Meta-analysis was performed on VEGF -1154 G > A polymorphism. Three case-control studies consisted of 683 women were included in the quantitative meta-analysis (305 RIF patients and 378 controls). Results showed that VEGF -1154A allele was significantly associated with RIF (OR 1.39, 95% CI 1.08-1.78, P-value = 0.01). The dominant genetic model showed that VEGF 1154AA plus VEGF 1154AG genotypes were more frequent in RIF patients than VEGF 1154GG genotype (OR 1.56, 95% CI 1.10-2.20, P-value = 0.01). However, the result under the recessive genetic model showed no significant difference (OR 1.67, 95% CI 0.92-3.03, P-value = 0.09).

CONCLUSION

VEGF -1154A allele may serve as one of the predisposing factors of RIF. Women with VEGF 1154 AA/GA genotypes were at higher risk of RIF. However, we should consider the haplotype effect of VEGF polymorphisms in future studies.

First-trimester serum BAFF:sFlt-1 ratio as a candidate early biomarker of spontaneous abortion

PROBLEM

Immunologic, angiogenic, and anti-angiogenic factors are associated with spontaneous abortion (SAB). B cell-activating factor (BAFF), a proliferation-inducing ligand (APRIL), placental growth factor (PlGF), and soluble fms-like tyrosine kinase-1 (sFlt-1) may play a role in SAB and may serve singly or in combination as an early biomarker of SAB.

METHOD OF STUDY

In this prospective observational study, serum sFlt-1, PIGF, BAFF, and APRIL levels were measured in the first trimester of pregnancy in a medically diverse group of women and in non-pregnant controls. Associations and discriminative values of first-trimester sFlt-1, PIGF, BAFF, and APRIL levels and the corresponding APRIL:BAFF, BAFF:sFlt-1, and sFlt-1:PlGF ratios with development of SAB were tested.

RESULTS

Median serum BAFF level was lower (p = .007) and median serum sFlt-1 level was higher (p < .001), in the first trimester of pregnancy than in non-pregnant controls. SAB developed in 27 of the pregnant women (11.3%), and first-trimester levels of BAFF (but not APRIL) and sFlt-1 (but not PIGF) were associated with SAB. Using optimal cutoffs determined through receiver operating characteristics curves, the best discriminator of SAB was the serum BAFF:sFlt-1 ratio, specifically among non-nulliparous women and women with prior SAB.

CONCLUSION

First-trimester serum BAFF:sFlt-1 ratio is a candidate indicator/predictor of SAB among non-nulliparous women and women with prior SAB. If validated through additional studies, then early identification of pregnant women at high risk for SAB through this simple blood test would assist in counseling and facilitate clinical trials of therapeutic interventions.

Steroid hormones and first trimester vascular remodeling

Successful implantation and placentation require neoangiogenesis and the remodeling of the uterine spiral arteries. Progesterone and estradiol control various of the placental functions, but their role in vascular remodeling remains controversial. Therefore, this chapter aims to summarize the current knowledge regarding the role of steroid hormones in the uteroplacental vascular remodeling during the first trimester of gestation.

Functional regulation of decidual macrophages during pregnancy

A successful pregnancy requires that the maternal immune system recognizes and tolerates the semi-allogeneic fetus without compromising the capability of protecting both mother and fetus from various pathogens. Decidual macrophages present unique phenotypes to play a key role in the establishment of the immunological aspects of maternal-fetal interaction. Dysfunction of decidual macrophages gives rise to pregnancy complications such as preeclampsia, recurrent spontaneous miscarriage, preterm labor and fetal growth restriction. Here, we reviewed the latest knowledge on the origin, differentiation, unique phenotype and function of macrophages in normal pregnancy and in pregnancy complications. We mainly focused on the significant roles of decidual macrophages in the process of extravillous trophoblast invasion, spiral arterial remodeling, decidual stromal cells cultivation and immune tolerance maintenance in normal pregnancy, and their pathological roles in pregnancy-related complications, offering more integrated information in maternal-fetal immunity.

Perivascular Stem Cell-Derived Cyclophilin A Improves Uterine Environment with Asherman's Syndrome via HIF1α-Dependent Angiogenesis

Asherman's syndrome (AS) is characterized by intrauterine adhesions or fibrosis resulting from scarring inside the endometrium. AS is associated with infertility, recurrent miscarriage, and placental abnormalities. Although mesenchymal stem cells show therapeutic promise for the treatment of AS, the molecular mechanisms underlying its pathophysiology remain unclear. We ascertained that mice with AS, like human patients with AS, suffer from extensive fibrosis, oligo/amenorrhea, and infertility. Human perivascular stem cells (hPVSCs) from umbilical cords repaired uterine damage in mice with AS, regardless of their delivery routes. In mice with AS, embryo implantation is aberrantly deferred, which leads to intrauterine growth restriction followed by no delivery at term. hPVSC administration significantly improved implantation defects and subsequent poor pregnancy outcomes via hypoxia inducible factor 1α (HIF1α)-dependent angiogenesis in a dose-dependent manner. Pharmacologic inhibition of HIF1α activity hindered hPVSC actions on pregnancy outcomes, whereas stabilization of HIF1α activity facilitated such actions. Furthermore, therapeutic effects of hPVSCs were not observed in uterine-specific HIF1α-knockout mice with AS. Secretome analyses of hPVSCs identified cyclophilin-A as the major paracrine factor for hPVSC therapy via HIF1α-dependent angiogenesis. Collectively, we demonstrate that hPVSCs-derived cyclophilin-A facilitates HIF1α-dependent angiogenesis to ameliorate compromised uterine environments in mice with AS, representing the major pathophysiologic features of humans with AS.

Physiologic Events of Embryo Implantation and Decidualization in Human and Non-Human Primates

Reproduction is a fundamental process for the preservation of the human species. This process requires a sequence of orchestrated events that are necessary for a successful pregnancy. Two of the most critical steps in the establishment of human pregnancy are implantation and decidualization, which are required for maternal interactions with the developing embryo. This review primarily highlights the physiological aspects of these two events and the adverse pregnancy outcomes from defective implantation and decidualization. The focus of this review is to provide a general concept of the mechanisms involved during the window of implantation, description of components involved in the process and possible pathologies that could disrupt the embryo implantation and decidualization and specifically as it applies to women and non-human primates.

Establishment of a three-dimensional model to study human uterine angiogenesis

STUDY QUESTION

Can primary human uterine microvascular endothelial cells (UtMVECs) be used as a model to study uterine angiogenic responses in vitro that are relevant in pregnancy?

SUMMARY ANSWER

UtMVECs demonstrated angiogenic responses when stimulated with proangiogenic factors, including sphingosine 1-phosphate (S1P), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), physiological levels of wall shear stress (WSS), human chorionic gonadotropin (hCG) and various combinations of estrogen and progesterone.

WHAT IS KNOWN ALREADY

During sprouting angiogenesis, signaling from growth factors and cytokines induces a monolayer of quiescent endothelial cells (ECs) lining the vasculature to degrade the extracellular matrix and invade the surrounding tissue to form new capillaries. During pregnancy and the female reproductive cycle, the uterine endothelium becomes activated and undergoes sprouting angiogenesis to increase the size and number of blood vessels in the endometrium.

STUDY DESIGN, SIZE, DURATION

The study was designed to examine the angiogenic potential of primary human UtMVECs using the well-characterized human umbilical vein EC (HUVEC) line as a control to compare angiogenic potential. ECs were seeded onto three-dimensional (3D) collagen matrices, supplemented with known proangiogenic stimuli relevant to pregnancy and allowed to invade for 24 h. Sprouting responses were analyzed using manual and automated methods for quantification.

PARTICIPANTS/MATERIALS, SETTING, METHODS

RT-PCR, Western blot analysis and immunostaining were used to characterize UtMVECs. Angiogenic responses were examined using 3D invasion assays. Western blotting was used to confirm signaling responses after proangiogenic lipid, pharmacological inhibitor, and recombinant lentiviral treatments. All experiments were repeated at least three times.

MAIN RESULTS AND THE ROLE OF CHANCE

After ensuring that UtMVECs expressed the proper endothelial markers, we found that UtMVECs invade 3D collagen matrices dose-dependently in response to known proangiogenic stimuli (e.g. S1P, VEGF, bFGF, hCG, estrogen, progesterone and WSS) present during early pregnancy. Invasion responses were positively correlated with phosphorylation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) and p42/p44 mitogen-activated protein kinase (ERK). Inhibition of these second messengers significantly impaired sprouting (P < 0.01). Gene silencing of membrane type 1-matrix metalloproteinase using multiple approaches completely abrogated sprouting (P < 0.001). Finally, UtMVECs displayed a unique ability to undergo sprouting in response to hCG, and combined estrogen and progesterone treatment.

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

The study of uterine angiogenesis in vitro has limitations and any findings many not fully represent the in vivo state. However, these experiments do provide evidence for the ability of UtMVECs to be used in functional sprouting assays in a 3D environment, stimulated by physiological factors that are produced locally within the uterus during early pregnancy.

WIDER IMPLICATIONS OF THE FINDINGS

We show that UtMVECs can be used reliably to investigate how growth factors, hormones, lipids and other factors, such as flow, affect angiogenesis in the uterus.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by NIH award HL095786 to K.J.B. The authors have no conflicts of interest.

Comparative serum proteome analysis reveals potential early pregnancy-specific protein biomarkers in pigs

In this study, the comparative serum proteome profile of Day 5, 12 and 16 of gestation, representing three early embryonic events, namely formation, elongation and implantation of blastocysts, and non-pregnant control were explored by a label-free quantitation-based mass spectrometric approach to identify early pregnancy biomarkers in pigs. A total of 131 proteins were identified with respect to different groups, out of which 105 were found to be differentially expressed proteins (DEPs). Among the DEPs, 54 and 66 proteins were found to be up and downregulated respectively in early pregnancy groups (fold change &gt;2) and the maximum number of upregulated proteins was observed in the Day 12 pregnancy stage. Functional classification and pathway analysis of the DEPs revealed involvement of most of the proteins in complement and coagulation cascades, metabolic processes and immune and inflammatory responses. Proteins such as glutathione peroxidise (GPX), pregnancy zone protein (PZP), thrombospondin-1 (THBS1), α-1-antitrypsin (AAT) and mannose-binding lectin C (MBLC) were differentially expressed during early pregnancy and actively involved in different pregnancy-related activities. To the best of our knowledge, this is the first report on comparative serum protein profiling of different early pregnancy stages in pigs and our results provide a set of proteins that can be used as potential biomarkers for early pregnancy diagnosis in pigs.

Endometrial injury increases expression of hypoxia-inducible factor and angiogenesis in the endometrium of women with recurrent implantation failure

RESEARCH QUESTION

The aim of this study was to compare expression of hypoxia-inducible factor 1-alpha (HIF-1α), angiogenesis and apoptosis in endometrial tissue near the implantation window of women with recurrent implantation failure (RIF) and in fertile control women, and to describe possible mechanisms of endometrial injury.

DESIGN

A controlled clinical study was conducted. Endometrial tissue specimens were obtained from 20 women undergoing IVF who had had at least three previous failed treatment cycles; normal endometrial specimens were obtained from 10 fertile control women.

RESULTS

HIF-1α expression was down-regulated in the endometrium of women with RIF compared with that of control women. In addition, micro-vessel density (MVD) was much lower in the endometrium of women with RIF than in that of the control women. Apoptosis was significantly reduced in the endometrium of the RIF group compared with the control group. Endometrial injury increased HIF-1α expression and MVD in endometrial samples of the RIF group, but apoptosis was not significantly altered.

CONCLUSIONS

HIF-1α expression, MVD and endometrial apoptosis were reduced in the peri-implantation endometrium of women with RIF. This suggests that altered endometrial HIF-1α expression and angiogenesis may contribute to implantation failure.

Steroid hormones induce in vitro human first trimester trophoblast tubulogenesis by the lysophosphatidic acid pathway

Successful implantation and placentation requires that extravillous cytotrophoblast acquires an endovascular phenotype and remodels uterine spiral arteries. Progesterone (P4) and estradiol (E2) control many of the placental functions, but their role in vascular remodeling remains controversial. Here, we investigated whether P4 and E2 regulate the acquisition of the human first trimester trophoblast endovascular phenotype, and the participation of the lysophosphatidic acid pathway. For this purpose, human first trimester HTR-8/SVneo cells were seeded on Geltrex and assayed for capillary-like tube formation. P4 and E2 increased HTR-8/SVneo tube formation in a concentration-dependent manner and this effect is mediated by the LPA3 receptor. Moreover, sex steroids increased the mRNA levels of the main enzyme that produce lysophosphatidic acid (lysophospholipase-D) but did not regulate LPA3 mRNA levels. Overall, we demonstrate that steroid hormones regulate HTR-8/SVneo trophoblast capillary-like structures formation and we propose that this process could be modulated directly or indirectly by mechanisms associated to the LPA/LPA3 pathway.

Human trophoblast invasion: new and unexpected routes and functions

Until recently, trophoblast invasion during human placentation was characterized by and restricted to invasion into uterine connective tissues and the uterine spiral arteries. The latter was explained to connect the arteries to the intervillous space of the placenta and to guarantee the blood supply of the mother to the placenta. Today, this picture has dramatically changed. Invasion of endoglandular trophoblast into uterine glands, already starting at the time of implantation, enables histiotrophic nutrition of the embryo prior to perfusion of the placenta with maternal blood. This is followed by invasion of endovenous trophoblasts into uterine veins to guarantee the drainage of fluids from the placenta back into the maternal circulation throughout pregnancy. In addition, invasion of endolymphatic trophoblasts into the lymph vessels of the uterus has been described. Only then, invasion of endoarterial trophoblasts into spiral arteries takes place, enabling hemotrophic nutrition of the fetus starting with the second trimester of pregnancy. This new knowledge paves the way to identify changes that may occur in pathological pregnancies, from tubal pregnancies to recurrent spontaneous abortions.

Spatiotemporal expression profile of proteases and immunological, angiogenic, hormonal and apoptotic mediators in rat placenta before and during intrauterine trophoblast migration

The gene and/or protein expression of proteases and immunological, angiogenic, hormonal and apoptotic mediators was evaluated in rat placenta before and during intrauterine trophoblast migration. The depth of interstitial and endovascular intrauterine trophoblast invasion and the immunohistochemical expression of vascular endothelial growth factor (VEGF), fetal liver kinase 1 (Flk1), interferon (IFN)-γ, migration inhibitory factor (MIF), and inducible nitric oxide synthase (iNOS; also known as nitric oxide synthase (NOS) 2) were evaluated. In addition, the expression of the Vegf, Flk1, placental growth factor (Pigf), soluble fms-like tyrosine kinase 1 (sFlt1), placental lactogen 1 (Pl1), proliferin-related protein (rPlf), placental leptin (Lep), Toll-like receptor 2 (Tlr2), Toll-like receptor 4 (Tlr4), Infg, Mif, tumour necrosis factor-α (Tnf), interleukin-10 (Il10), Nos2, caspase 3 (Casp3), Bax, Bcl2, matrix metalloproteinase 2 (Mmp2) and matrix metalloproteinase 9 (Mmp9) genes was determined by real-time reverse transcription-polymerase chain reaction. At 10 days gestation, gene expression of Tlr2, Tlr4, Tnf, Infg, Il10, Casp3, Pigf, sFlt1 and Lep (P<0.05) were higher than at 14 and/or 19 days of gestation. The beginning of intrauterine trophoblast invasion, i.e., at 14 days of gestation, coincided with higher gene and/or protein expression of MMP9, VEGF, Flk1, NOS2, MIF, BAX and rPlf compared to days 10 and 19 (P<0.05). In contrast, gene expression of Mmp2 and Pl1 was higher at the end of trophoblast invasion compared to 10 and 14 days of gestation (P<0.05). In conclusion, before intrauterine trophoblast migration, expression of TLRs and immunological and pro-apoptotic mediators is higher, whereas the beginning of trophoblast migration is characterised by higher expression of the pro-angiogenic factors NOS2 and MMP9. In contrast, MMP2 and PL1 expression is higher at the end of intrauterine trophoblast migration.

Abnormal expression of microRNA-575 leads to missed abortion through regulating apoptosis and angiogenesis

Numerous microRNA (miR) are important for placental development and function. miR-575 has been demonstrated to be upregulated in maternal placenta in patients who have experienced a miscarriage. The present study aimed to explore the role of abnormal expression of miR-575 in missed abortion (MA) and to further analyze the potential molecular mechanisms. Embryo villus tissue samples were extracted from 10 childless women with MA and 10 fertile women without a history of MA. Additionally, human choriocarcinoma cells, JEG-3, were used in the present study, which were transfected with miR-575 mimic, inhibitor and scramble. The expression of miR-575 in embryo villus tissues and in JEG-3 cells was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Apoptosis in villus tissues of patients with MA and in JEG-3 cells of miR-575 mimic, inhibitor and scramble groups were detected by flow cytometry. Furthermore, the expression levels of apoptosis-related proteins, including B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax) and phosphorylated (p)-p53, and angiogenesis-related proteins, including vascular endothelial growth factor (VEGF) and angiopoietin 2 (Ang-2), were measured by RT-qPCR and western blotting. Additionally, the target of miR-575 was predicted and clarified by luciferase reporter assay. miR-575 was significantly overexpressed in MA villus tissue compared with normal tissue (P<0.05). The percentage of apoptotic cells in MA embryo villus tissue was significantly higher than that in normal tissue (P<0.05). After JEG-3 cells were transfected with miR-575 inhibitor, the expression of miR-575 and the percentage of apoptotic cells decreased significantly compared with the control (P<0.05). MiR-575 suppression significantly increased the expression of Bcl-2 (P<0.05), and decreased the expressions of Bax (P<0.05) and p-p53 (P<0.01) compared with the control. Furthermore, miR-575 suppression significantly increased the expressions of angiogenesis-related proteins, Ang-2 and VEGF (P<0.01). Superoxide dismutase 2 was identified as the target of miR-575. Therefore, abnormal expression of miR-575 may lead to MA through regulating apoptosis and angiogenesis. Inhibition of miR-575 may inhibit apoptosis and promote angiogenesis in MA.

Proangiogenic Activity of Endometrial Epithelial and Stromal Cells in Response to Estradiol in Gelatin Hydrogels

Biomaterial vascularization remains a major focus in the field of tissue engineering. Biomaterial culture of endometrial cells is described as a platform to inform the design of proangiogenic biomaterials. The endometrium undergoes rapid growth and shedding of dense vascular networks during each menstrual cycle mediated via estradiol and progesterone in vivo. Cocultures of endometrial epithelial and stromal cells encapsulated within a methacrylamide-functionalized gelatin hydrogel are employed. It is reported that proangiogenic gene expression profiles and vascular endothelial growth factor production are hormone dependent in endometrial epithelial cells, but that hormone signals have no effect on human telomerase reverse transcriptase (hTERT)-immortalized endometrial stromal cells. This study subsequently examines whether the magnitude of epithelial cell response is sufficient to induce changes in human umbilical vein endothelial cell network formation. Incorporation of endometrial stromal cells improves vessel formation, but co-culture with endometrial epithelial cells leads to a decrease in vascular formation, suggesting the need for stratified cocultures of endometrial epithelial and stromal cells with endothelial cells. Given the transience of hormonal signals within 3D biomaterials, the inclusion of sex hormone binding globulin (SHBG) to alter the bioavailability of estradiol within the hydrogel is reported, demonstrating a strategy to reduce diffusive losses via SHBG-mediated estradiol sequestration.

Chlamydia trachomatis infection of human endometrial stromal cells induces defective decidualisation and chemokine release

Miscarriage affects ~20% of pregnancies and maternal infections account for ~15% of early miscarriages. Chlamydia trachomatis (Ct) has been associated with miscarriage but the underlying mechanisms are unknown. Successful implantation requires endometrial stromal cell (ESC) decidualisation. Maintenance of pregnancy requires angiogenesis, establishment of the correct cellular milieu and trophoblast invasion, all of which involve the action of chemokines. Our objective was to determine whether Ct infection impacts upon ESC decidualisation and chemokine secretion. Human primary ESC were decidualised in-vitro, infected with Ct serovar E, and changes in expression of genes of interest were measured using RT-PCR, proteomic array and ELISA. We demonstrate for the first time that Ct can infect and proliferate in ESC. Expression of the decidualisation marker prolactin was decreased in Ct-infected ESC at both mRNA and protein levels. Ct infection altered the chemokine profile of decidualised ESC as shown by proteomic array. Chemokines CXCL12 and CXCL16, important for trophoblast invasion, were analysed further and expression was reduced in infected decidualised cells at mRNA and protein levels. Our data indicate that Ct infection of ESC impairs decidualisation and alters chemokine release. These findings at least partially explain how Ct infection could result in adverse pregnancy outcomes.

Human Extravillous Trophoblasts Penetrate Decidual Veins and Lymphatics before Remodeling Spiral Arteries during Early Pregnancy

In humans, the defective invasion of the maternal endometrium by fetal extravillous trophoblasts (EVTs) can lead to insufficient perfusion of the placenta, resulting in pregnancy complications that can put both mother and baby at risk. To study the invasion of maternal endometrium between (W)5.5–12 weeks of gestation by EVTs, we combined fluorescence in situ hybridization, immunofluorescence and immunohistochemistry to determine the presence of (male) EVTs in the vasculature of the maternal decidua. We observed that interstitial mononuclear EVTs directly entered decidual veins and lymphatics from W5.5. This invasion of decidual veins and lymphatics occurred long before endovascular EVTs remodelled decidual spiral arteries. This unexpected early entrance of interstitial mononuclear EVTs in the maternal circulation does not seem to contribute to the materno-placental vascular connection directly, but rather to establish (and expand) the materno-fetal interface through an alternative vascular route.

Bone mesenchymal stem cells improve pregnancy outcome by inducing maternal tolerance to the allogeneic fetus in abortion-prone matings in mouse

INTRODUCTION

The successful pregnancy depends on maternal immune tolerance against the fetus. It has been reported that MSCs (mesenchymal stem cells) could play a regulatory role on immune cells such as CD4⁺T cells, macrophages and NK cells, but their effect on recurrent miscarriage is unknown.

STUDY DESIGN

In a prospective study, the abortion-prone (CBA/J × DBA/2) H-2^d × H-2^k mice were utilized. Female CBA/J mice (8-10 weeks old) were injected with vehicle or MSCs via tail vein or uterine horns, and 14 days later, they were mated with DBA/2 males for the following experiments.

RESULTS

Comparing with the control group, the embryo resorption rate in MSCs-horn injection group was dramatically decreased. MSCs were mainly located at the maternal-fetal interface, indicating that the reduction of resorption rate was due to MSCs' local effect. No matter which treatment was given, there was no significant difference in the levels of IL-4, IL-10, TNF-α and IFN-γ in CD4⁺T cells and IL-10 and IL-12 in macrophages in spleens among each group. However, in contrast to other groups, the levels of IL-4 and IL-10 in CD4⁺T cells localized at the maternal-fetal interface in MSCs-horn injection group were dramatically increased, and TNF-α and IFN-γ levels were notably decreased. While IL-10 expressed in macrophages was obviously higher than other groups and IL-12 in macrophages was significantly lower than other groups.

CONCLUSIONS

The findings indicate that MSCs injection through uterine horns could decrease embryo resorption rate.

Hypoxia inducible factor and microvessels in peri-implantation endometrium of women with recurrent miscarriage

OBJECTIVE

To compare the expression of hypoxia inducible factor 1α (HIF1α) and micro-blood vessels in endometrium around the time of embryo implantation in women with recurrent miscarriage and fertile controls.

DESIGN

Retrospective study.

SETTING

University hospitals.

PATIENT(S)

Sixty women: 24 with recurrent miscarriage and 36 with proven fertility.

INTERVENTION(S)

Endometrial biopsy samples obtained precisely 7 days after luteinization hormone (LH) surge in a natural cycle.

MAIN OUTCOME MEASURE(S)

Immunohistochemical analysis to determine expression of HIF1α and micro-blood vessels as identified by von Willebrand factor (vWF) in endometrium; semiquantitative analysis using H-score analysis of staining intensity for HIF1α in the luminal epithelium, glandular epithelium, and stroma, separately; number, diameter, and volume of vWF-positive endometrial micro-vessels as counted by Image J software.

RESULT(S)

The luminal epithelial and stromal expression of HIF1α in women with recurrent miscarriage was higher than found in the fertile controls, with the change in the luminal epithelium reaching the highest statistical significance. There was no statistically significant difference in HIF1α expression in glandular epithelium between the two groups. An increased number as well as volume of micro-blood vessels was observed in women with recurrent miscarriage although the mean diameter of the micro-blood vessels did not statistically significantly differ between the two groups.

CONCLUSION(S)

We have found an aberrant expression of HIF1α and micro-vessel number and volume in the peri-implantation endometrium of women with recurrent miscarriage, suggesting that altered hypoxia and vascularization status may account for the endometrial contribution to recurrent miscarriage.

KDR gene polymorphisms and idiopathic recurrent spontaneous abortion

OBJECTIVE

Process of angiogenesis is essential for successful gestation. Disruption in this pathway leads to various undesirable consequences in pregnancy such as recurrent spontaneous abortion (RSA). One of the most important genes involved in angiogenesis is kinase-insert domain-containing receptor (KDR). This study aimed to investigate the associations between two single-nucleotide polymorphisms (SNPs) of KDR gene, 1719A > T and 1192G > A, with idiopathic RSA in south-east Iran.

METHODS

A total of 230 women, including 110 women with a history of at least two consecutive spontaneous miscarriages and 120 healthy women were recruited in this study. Genomic DNA was extracted from peripheral blood samples of participants using the Salting out method. The KDR 1719A > T and 1192G > A polymorphisms were genotyped by the standard amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) technique.

RESULTS

For the case group, frequencies of 2.73%, 30% and 67.27% were observed for AA, AT and TT genotypes in1719A > T SNP, respectively, and the genotype frequencies for controls were equal to AA = 3.33%, AT = 32.5% and TT = 64.17%. Distribution of genotypes in 1192G > A SNP in the case group was 79.1%, 19.1% and 1.8% for GG, AG and AA, respectively, whereas the corresponding values for the controls were GG  =  80%, AG  =  20% and AA  =  0. No significant difference was found between the case and control groups based on the frequency of KDR gene polymorphisms with the susceptibility to RSA.

CONCLUSIONS

There is no association between these two SNPs of KDR gene and the susceptibility to RSA in women from south-east Iran.

Placental membrane-type metalloproteinases (MT-MMPs): Key players in pregnancy

Membrane-type matrix metalloproteinases (MT-MMPs) are a sub-family of zinc-dependent endopeptidases involved in the degradation of the extracellular matrix. Although MT-MMPs have been mainly characterized in tumor biology, they also play a relevant role during pregnancy. Placental MT-MMPs are required for cytotrophoblast migration and invasion of the uterine wall and in the remodeling of the spiral arteries. They are involved in the fusion of cytotrophoblasts to form the syncytiotrophoblast as well as in angiogenesis. All these processes are crucial for establishing and maintaining a successful pregnancy and, thus, MT-MMP activity has to be tightly regulated in time and space. Indeed, a de-regulation of MT-MMP expression has been linked with pregnancy complications such as preeclampsia (PE), fetal growth restriction (FGR), gestational diabetes mellitus (GDM) and was also found in maternal obesity. Here we review what is currently known about MT-MMPs in the placenta, with a focus on their general features, their localization and their involvement in pregnancy disorders.

Rac1 Regulates Endometrial Secretory Function to Control Placental Development

During placenta development, a succession of complex molecular and cellular interactions between the maternal endometrium and the developing embryo ensures reproductive success. The precise mechanisms regulating this maternal-fetal crosstalk remain unknown. Our study revealed that the expression of Rac1, a member of the Rho family of GTPases, is markedly elevated in mouse decidua on days 7 and 8 of gestation. To investigate its function in the uterus, we created mice bearing a conditional deletion of the Rac1 gene in uterine stromal cells. Ablation of Rac1 did not affect the formation of the decidua but led to fetal loss in mid gestation accompanied by extensive hemorrhage. To gain insights into the molecular pathways affected by the loss of Rac1, we performed gene expression profiling which revealed that Rac1 signaling regulates the expression of Rab27b, another GTPase that plays a key role in targeting vesicular trafficking. Consequently, the Rac1-null decidual cells failed to secrete vascular endothelial growth factor A, which is a critical regulator of decidual angiogenesis, and insulin-like growth factor binding protein 4, which regulates the bioavailability of insulin-like growth factors that promote proliferation and differentiation of trophoblast cell lineages in the ectoplacental cone. The lack of secretion of these key factors by Rac1-null decidua gave rise to impaired angiogenesis and dysregulated proliferation of trophoblast cells, which in turn results in overexpansion of the trophoblast giant cell lineage and disorganized placenta development. Further experiments revealed that RAC1, the human ortholog of Rac1, regulates the secretory activity of human endometrial stromal cells during decidualization, supporting the concept that this signaling G protein plays a central and conserved role in controlling endometrial secretory function. This study provides unique insights into the molecular mechanisms regulating endometrial secretions that mediate stromal-endothelial and stromal-trophoblast crosstalk critical for placenta development and establishment of pregnancy.

During early pregnancy, a succession of molecular interactions between the uterus and the developing embryo ensures reproductive success. Although it is conceivable that signaling cues originating in the uterus impact on the developing embryo at the time of placenta establishment, the precise mechanisms regulating the maternal-fetal crosstalk remain unknown. Impaired uterine functions during early pregnancy are likely to contribute to abnormal embryo development and various diseases of pregnancy, such as recurrent miscarriage, preeclampsia, and intrauterine growth restriction. This study provides insights into the molecular mechanisms by which Rac1, a signaling molecule expressed in the decidua, controls uterine secretions that mediate maternal-fetal communication critical for placental development and establishment of pregnancy.

Association of VEGF genetic polymorphisms with recurrent spontaneous abortion risk: a systematic review and meta-analysis

Background

Studies of the associations between the genetic polymorphisms of the vascular endothelial growth factor (VEGF) gene and recurrent spontaneous abortion (RSA) have revealed conflicting results. The present meta-analysis was performed to provide a more precise estimation of these relationships and to explore potential sources of heterogeneity that may have influenced the reported disparities.

Methods

An extensive literature search for relevant studies was conducted on PubMed, Embase, and The Cochrane Library through June 6, 2014. Crude odds ratio (OR) with 95% confidence intervals were calculated.

Results

10 case-control studies including 1,832 RSA patients and 2,271 healthy controls were identified. Meta-analysis indicated that rs1570360, rs3025039, rs2010963, and rs3025020 polymorphisms in the VEGF gene correlated with elevated RSA risk. The rs1570360 variant was statistically significantly relevant to RSA risk among non-Asian populations. Interestingly, the rs3025039 variant was statistically significantly relevant to RSA risk among Asian populations.

Conclusions

The current meta-analysis indicates that rs1570360, rs3025039, rs2010963, and rs3025020 polymorphisms increase RSA susceptibility. Moreover, rs1570360 and rs3025039 polymorphisms may play various roles in RSA susceptibility in various geographic groups.

Uterine natural killer cells: supervisors of vasculature construction in early decidua basalis

Mammalian pregnancy involves tremendousde novomaternal vascular construction to adequately support conceptus development. In early mouse decidua basalis (DB), maternal uterine natural killer (uNK) cells oversee this process directing various aspects during the formation of supportive vascular networks. The uNK cells recruited to early implantation site DB secrete numerous factors that act in the construction of early decidual vessels (neoangiogenesis) as well as in the alteration of the structural components of newly developing and existing vessels (pruning and remodeling). Although decidual and placental development sufficient to support live births occur in the absence of normally functioning uNK cells, development and structure of implantation site are optimized through the presence of normally activated uNK cells. Human NK cells are also recruited to early decidua. Gestational complications including recurrent spontaneous abortion, fetal growth restriction, preeclampsia, and preterm labor are linked with the absence of human NK cell activation via paternally inherited conceptus transplantation antigens. This review summarizes the roles that mouse uNK cells normally play in decidual neoangiogenesis and spiral artery remodeling in mouse pregnancy and briefly discusses changes in early developmental angiogenesis due to placental growth factor deficiency.

The Role of Uterine NK Cells in Normal Reproduction and Reproductive Disorders

The human endometrium contains a substantial population of leucocytes which vary in distribution during the menstrual cycle and pregnancy. An unusual population of natural killer (NK) cells, termed uterine NK (uNK) cells, are the most abundant of these cells in early pregnancy. The increase in number of uNK cells in the mid-secretory phase of the cycle with further increases in early pregnancy has focused attention on the role of uNK cells in early pregnancy. Despite many studies, the in vivo role of these cells is uncertain. This chapter reviews current information regarding the role of uNK cells in healthy human pregnancy and evidence indicating their importance in various reproductive and pregnancy problems. Studies in humans are limited by the availability of suitable tissues and the limitations of extrapolation from animal models.

Ultrastructure alteration of decidual natural killer cells in women with unexplained recurrent miscarriage: a possible association with impaired decidual vascular remodelling

This study aimed to evaluate the extent of remodelling of intra-decidual segments of the spiral arteries in human deciduas between the 6th and 10th gestational weeks in women with unexplained recurrent miscarriages (RM) in comparison to gestational-matched controls. A possible association with the number, immunoexpressive behaviour and ultrastructural changes of decidual natural killer cells (dNKCs) was investigated. Decidual biopsies were obtained from RM cases (n = 40) and women with no history of spontaneous miscarriage and at least one live birth at term (n = 30). Staining was performed using PAS, anti-CD34 and anti-CD56 antibodies, using an avidin-biotin-peroxides technique. Analysis by means of light and transmission electron microscopy was employed. To determine the extent of remodelling of decidual vessels, a quantitative score was analysed using histological criteria of vascular transformation and then related to the number of CD56(+) dNKCs. In RM, dNKCs were distributed among decidual cells and around the vessels. They possessed numerous polyploidic protrusions on cell membranes crossing from one cell to another. The cells became more irregular and exhibited heterogeneous electron-dense granules in their cytoplasm compared to controls. The non-remodelling score and number of dNKCs were significantly increased in RM group (p < 0.001). The number of dNKCs was significantly correlated with the scores in both control (r = 0.491; p = 0.006) and RM (r = 0.852; p < 0.001) groups. It appears that dNKCs play a key role in impaired decidual artery remodelling that may be involved with early RM. This may be due to increased numbers of cells or impaired cellular interactions resulting from alterations to the ultrastructure.

Risk of placental dysfunction disorders after prior miscarriages: a population-based study

OBJECTIVE

The objective of the investigation was to study the association between prior miscarriages and the risks of placental dysfunction disorders, including preeclampsia, stillbirth, birth of a small for gestational age (SGA) infant, placental abruption, and spontaneous preterm birth.

STUDY DESIGN

In a population-based cohort study including 619,587 primiparous women, we estimated risks of placental dysfunction disorders for women with 1 (n = 68,185), 2 (n = 11,410) and 3 or more (n = 3823) self-reported prior miscarriages. Risks were calculated as odds ratios by unconditional logistic regression analysis and adjustments were made for maternal age, early pregnancy body mass index, height, smoking habits, country of birth, years of formal education, in vitro fertilization, chronic hypertension, pregestational diabetes, hypothyroidism, systemic lupus erythematosis, fetal sex, and year of childbirth.

RESULTS

Compared with women with no prior miscarriage, women with 1 prior miscarriage had almost no increased risks. Women with 2 prior miscarriages had increased risks of spontaneous preterm birth, preterm (<37 weeks) SGA infant, and placental abruption. The rates of all disorders were higher for women with 3 or more prior miscarriages compared with women without prior miscarriages: preeclampsia, 5.83% vs 4.27%; stillbirth, 0.69% vs 0.33%, SGA infant, 5.09% vs 3.22%, placental abruption, 0.81% vs 0.41%; and spontaneous preterm birth, 6.45% vs 4.40%. The adjusted odds ratios for preterm (<37 weeks) disorders in women with 3 prior miscarriages were approximately 2.

CONCLUSION

History of 2 or more miscarriages is associated with an increased risk of placental dysfunction disorders and should be regarded as a risk factor in antenatal care.

Immunological modes of pregnancy loss: inflammation, immune effectors, and stress

Inflammatory immune response plays a key role in reproductive failures such as multiple implantation failures (MIF), early pregnancy loss, and recurrent pregnancy losses (RPL). Cellular immune responses particularly mediated by natural killer (NK), and T cells are often dysregulated in these conditions. Excessive or inappropriate recruitment of peripheral blood NK cells to the uterus may lead to cytotoxic environment in utero, in which proliferation and differentiation of trophoblast is hampered. In addition, inadequate angiogenesis by uterine NK cells often leads to abnormal vascular development and blood flow patterns, which, in turn, leads to increased oxidative stress or ischemic changes in the invading trophoblast. T-cell abnormalities with increased Th1 and Th17 immunity, and decreased Th2 and T regulatory immune responses may play important roles in RPL and MIF. A possible role of stress in inflammatory immune response is also reviewed.

Quantitative proteomics analysis of altered protein expression in the placental villous tissue of early pregnancy loss using isobaric tandem mass tags

Many pregnant women suffer miscarriages during early gestation, but the description of these early pregnancy losses (EPL) can be somewhat confusing because of the complexities of early development. Thus, the identification of proteins with different expression profiles related to early pregnancy loss is essential for understanding the comprehensive pathophysiological mechanism. In this study, we report a gel-free tandem mass tags- (TMT-) labeling based proteomic analysis of five placental villous tissues from patients with early pregnancy loss and five from normal pregnant women. The application of this method resulted in the identification of 3423 proteins and 19647 peptides among the patient group and the matched normal control group. Qualitative and quantitative proteomic analysis revealed 51 proteins to be differentially abundant between the two groups (≥1.2-fold, Student's t-test, P < 0.05). To obtain an overview of the biological functions of the proteins whose expression levels altered significantly in EPL group, gene ontology analysis was performed. We also investigated the twelve proteins with a difference over 1.5-fold using pathways analysis. Our results demonstrate that the gel-free TMT-based proteomic approach allows the quantification of differences in protein expression levels, which is useful for obtaining molecular insights into early pregnancy loss.

The role of VEGF and its receptors in the etiology of early pregnancy loss

OBJECTIVE

This study aimed to investigate the role of vascular endothelial growth factor (VEGF) and its receptors (VEGFR1, VEGFR2) in maternal and embryonic tissues in the etiology of early pregnancy loss.

METHODS

Immunohistochemistry was used to analyze the expression of VEGF and its receptors in placental and decidual tissues of 80 women with spontaneous incomplete abortion (n = 20), missed abortion (n = 20), blighted ovum (n = 20) and from early terminated pregnancies (n = 20).

RESULTS

Compared with the controls, all study groups showed weaker VEGF immunoreactivity in cytotrophoblasts and syncytiotrophoblasts of placental villi and endothelial cells of decidua (p = 0.002, p = 0.003, p < 0.001 respectively). Decidual endothelial cells of study groups except for blighted ovum showed weaker VEGFR1 immunoreactivity as compared to controls (p < 0.001). Placental villi cytotrophoblasts, syncytiotrophoblasts, decidual endothelial cells and endometrial gland epithelial cells showed weaker VEGFR2 immunoreactivity in all study groups compared to controls (p < 0.001). Placental villi endothelial cells showed the weakest VEGFR2 immunoreactivity in incomplete abortion group and the strongest staining in the blighted ovum group (p < 0.001).

CONCLUSION

These results suggest that decreased expression of VEGFR1 in decidua and weaker VEGF and VEGFR2 expression in placental villi and decidua may be associated with early pregnancy loss.

Relationship between VEGFA polymorphisms and serum VEGF protein levels and recurrent spontaneous miscarriage

STUDY QUESTION

Is recurrent spontaneous miscarriage (RSM) associated with changes in vascular endothelial growth factor (VEGF) serum levels, and with polymorphisms in the VEGFA gene?

SUMMARY ANSWER

Reduced serum VEGF levels, and VEGFA -460T/C (rs833061), 398G/A (rs833068), -583T/C (rs3025020) variants, were associated with RSM.

WHAT IS KNOWN ALREADY

Reduced expression of VEGF has been linked with spontaneous miscarriage, likely due to defective fetal and placental angiogenesis. Since VEGF production is in part inherited, VEGFA polymorphisms associated with altered VEGF secretion have been investigated for their association with RSM, often with variable conclusions.

STUDY DESIGN, SIZE, DURATION

A retrospective case-control study, which was conducted between January 2011 and April 15, 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Subjects comprised 296 women with RSM (mean age: 31.6 ± 5.4 year), and 305 age-matched (mean age: 31.6 ± 4.9 year) control Arab women, who had attended outpatient obstetrics and gynecology clinics in two teaching hospitals in Bahrain. VEGFA -2578C/A (rs699947), -460T/C (rs833061), -1154G/A (rs15703060), -634G/C (rs2010963), 398G/A (rs833068), 497G/A (rs833070), -583T/C (rs3025020) and 936C/T (rs3025039) genotyping was done by real-time PCR, with defined clusters; VEGF serum levels were measured by ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

Higher minor allele frequency (MAF) and genotype distribution of -460T/C [corrected P (Pc) = 0.003], 398G/A (Pc = 0.016) and -583T/C (Pc < 0.001) single nucleotide polymorphisms (SNPs) were seen in RSM cases than control women. Increased RSM risk was seen with homozygous -460T/C and 398G/A SNPs and with heterozygous -583T/C, which had a stronger effect when homozygous. Serum VEGF levels were significantly reduced in RSM cases compared with control women (P = 0.016), and correlated with -460T/C, 398G/A and -583T/C genotypes. Haploview analysis revealed heterogeneity in linkage disequilibrium between VEGFA variants, and two blocks were identified: Block 1 comprising -2578C/A, -460T/C and -1154G/A, while Block 2 contained -634G/C, 398G/A, 497G/A, -583T/C and 936C/T. Both negatively and positively RSM-associated 3-locus (Block 1) and 5-locus (Block 2) VEGFA haplotypes were identified, after controlling for a number of covariates.

LIMITATIONS, REASONS FOR CAUTION

The study was retrospective and can only demonstrate association and not a cause-effect relationship. Furthermore, it was limited to Bahraini Arabs,thereby necessitating parallel studies on other ethnic groups.

WIDER IMPLICATIONS OF THE FINDINGS

Reduced VEGF secretion, and specific VEGFA variants may contribute to the pathogenesis of RSM. However, the association of VEGFA SNPs with RSM appears to be independent of their association with altered VEGF serum levels. The differential association of VEGFA variants with RSM is in line with previous findings on the contribution of ethnicity/racial background to genetic association studies.

Expression of ATF4 and VEGF in chorionic villus tissue in early spontaneous abortion

OBJECTIVE

To explore the relationship between early spontaneous abortion (SA) and the expression of activating transcription factor 4 (ATF4) and vascular endothelial growth factor (VEGF).

STUDY DESIGN

The expression of ATF4 and VEGF protein and mRNA in villi from first trimester spontaneous abortion (SA, n=30) and normal pregnancy (NP, n=30) were detected by immunohistochemistry and fluorescent quantitative polymerase chain reaction (FQ-PCR).

RESULTS

Both protein and mRNA expressions of ATF4 and VEGF in the SA group were significantly lower than in the NP group (P<0.01). Their proteins are expressed mainly in syncytiotrophoblast, cytotrophoblast and villous stromal cells. Correlation analysis showed that the expression of ATF4 was positively correlated with that of VEGF in the SA group (r=0.717, P<0.01).

CONCLUSION

Lower expression of ATF4 and VEGF genes in chorionic villus tissue may participate in the pathogenesis of spontaneous abortion.

Does ambient air pollutants increase the risk of fetal loss? A case-control study

OBJECTIVE

To examine the associations between the ambient air pollution and early fetal loss.

STUDY DESIGN

A retrospective case-control study was conducted. 959 fetal losses and 959 normal intrauterine pregnancies within 14 weeks of pregnancy in 15 general or obstetrics and gynecology hospitals were selected into case and control groups, respectively. Data based on hospital records and national pollution monitor station records were collected. Logistic regression model was conducted to examine the associations between 4 ambient air pollutants (SO2, PM10, NO2 and TSP) exposures and fetal loss.

RESULTS

The ratio of fetal loss to termination of pregnancy for heating months (2.28 %) was significantly (P < 0.001) higher than that for the non-heating months (1.77 %). Logistic regression suggested that fetal loss within 14 weeks was associated with higher exposure to SO2 (OR = 19.76, 95 % CI 2.34-166.71) and TSP (OR = 2.04, 95 % CI 1.01-4.13) in the first month of pregnancy.

CONCLUSION

Exposure to high levels of SO2 and TSP during the first month of pregnancy was associated with an increased risk of fetal loss in early pregnancy.