Does plasminogen activator inhibitor-1 (PAI-1) control trophoblast invasion? A study of fetal and maternal tissue in intrauterine, tubal and molar pregnancies

Systematic review and meta-analysis of association between plasminogen activator inhibitor-1 4G/5G polymorphism and recurrent pregnancy loss: an update

BACKGROUND

We conducted this systematic review and meta-analysis to better understand the association between rs1799762 PAI-1 gene polymorphism and the risk of RPL.

METHODS

A systematic search for studies that assessed the association between PAI-1 4G/5G polymorphism and RPL risk published in search sources, PubMed/Medline, ISI Web of Knowledge, Scopus, and Google Scholar till January 2024 was conducted.

RESULTS

There were 23 case-control studies in total, with a high degree of statistical heterogeneity among them which indicated the need for subgroup analysis. We found a significant positive association between the risk of RPL and 4G/4G PAI-1 (OR: 2.57; 95% CI: 1.69-3.90), likewise 4G/5G (OR: 2/02 95% CI: 1.39-2.92) and mixed genotype (4G/4G+4G/5G) (OR: 2.31 95% CI: 1.81-2.93). Considering the ethnicity, the 4G/4G polymorphism is significantly associated with Asian descent (OR: 2.10; CI: 1.65-2.69) while the strong association (OR: 6.47; CI: 3.23-12.97) observed in the Greater Middle East descent is not statistically significant (P=0.16). PAI-1 4G/5G polymorphism association with RPL was only significant in Greater Middle East descent (OR: 2.93; CI: 2.41-3.56), and mixed genotype was significantly associated with RPL in Asian (OR: 2.37; CI: 1.55-3.61), Greater Middle East (OR: 3.01; CI: 2.16-4.19), and European populations (OR: 1.38; CI: 0.91-2.10). The association between RPL and PAI-1 4G/4G was significant for RPLs both under 12 weeks (OR: 1.82; 95% CI: 1.34-2.47), and under 24 weeks (OR: 1.46; 95% CI: 1.11-1.92), while considering heterozygote form the association was only significant for RPLs under 24 weeks (OR: 1.91; 95% CI: 1.58-2.31). Regarding the mixed genotype, there is a significant positive association between PAI-1 and RPL for RPLs under 12 weeks (OR: 2.09; 95% CI: 1.49-2.93), and under 24 weeks (OR: 2.10; 95% CI: 1.52-2.92).

CONCLUSIONS

Our findings indicate a significant association between the rs1799762 PAI-1 polymorphism and the risk of RPL.

Exploring the presence of markers of decidualization in the fallopian tubes: a systematic review

The fallopian tubes (FTs) are part of the female upper genital tract. The healthy FT provides the biological environment for successful fertilization and facilitates the subsequent movement of the conceptus to the endometrial cavity. However, when the FT is damaged, as with salpingitis, pyosalpinx, and hydrosalpinx, it may increase the risk of an ectopic pregnancy, a life-threatening condition. Decidualization refers to a multifactorial process by which the endometrium changes to permit blastocyst implantation. The decidualization reaction is vital for endometrial receptivity during the window of implantation. To date, no comprehensive review that collates evidence on decidualization in the human FT has been conducted. Therefore, the aim of this review is to compile the current evidence on cellular decidualization occurring in the healthy and pathological FT in women of reproductive age. A literature search was conducted using five databases and identified 746 articles, 24 of which were analyzed based on inclusion and exclusion criteria. The available evidence indicates that the FT are able to undergo decidual changes under specific circumstances; however, the exact mechanism by which this occurs is poorly understood. Further research is needed to elucidate the mechanism by which decidualization can occur in the FT.

"Super" SERPINs-A stabilizing force against fibrinolysis in thromboinflammatory conditions

The superfamily of serine protease inhibitors (SERPINs) are a class of inhibitors that utilise a dynamic conformational change to trap and inhibit their target enzymes. Their powerful nature lends itself well to regulation of complex physiological enzymatic cascades, such as the haemostatic, inflammatory and complement pathways. The SERPINs α2-antiplasmin, plasminogen-activator inhibitor-1, plasminogen-activator inhibitor-2, protease nexin-1, and C1-inhibitor play crucial inhibitory roles in regulation of the fibrinolytic system and inflammation. Elevated levels of these SERPINs are associated with increased risk of thrombotic complications, obesity, type 2 diabetes, and hypertension. Conversely, deficiencies of these SERPINs have been linked to hyperfibrinolysis with bleeding and angioedema. In recent years SERPINs have been implicated in the modulation of the immune response and various thromboinflammatory conditions, such as sepsis and COVID-19. Here, we highlight the current understanding of the physiological role of SERPINs in haemostasis and inflammatory disease progression, with emphasis on the fibrinolytic pathway, and how this becomes dysregulated during disease. Finally, we consider the role of these SERPINs as potential biomarkers of disease progression and therapeutic targets for thromboinflammatory diseases.

Roles of TGF-β Superfamily Proteins in Extravillous Trophoblast Invasion

Following embryo implantation, extravillous trophoblasts (EVTs) invade the maternal decidua to a certain extent during early pregnancy, which is critical for normal placentation and successful pregnancy in humans. Although sharing a similar protein structure, the transforming growth factor-β (TGF-β) superfamily members exert divergent functions in regulating EVT invasion, which contributes to a relative balance of TGF-β superfamily proteins in precisely modulating this process at the maternal-fetal interface during the first trimester of pregnancy. This review details recent advances in our understanding of the functions of TGF-β superfamily members and their corresponding receptors, signaling pathways, and downstream molecular targets in regulating human EVT invasion from studies using various in vitro or ex vivo experimental models. Also, the relevance of these discoveries about TGF-β superfamily members to adverse pregnancy outcomes is summarized. The application of 3D culture trophoblast organoids, single-cell sequencing, and microfluidic assays in EVT invasion studies will help better reveal the molecular mechanisms through which TGF-β superfamily members regulate human EVT invasion, shedding light on the development of innovative strategies for predicting, diagnosing, treating, and preventing adverse human pregnancy outcomes related to EVT invasion dysfunction.

Neutrophil and Neutrophil-to-Lymphocyte Ratio as Clinically Predictive Risk Markers for Recurrent Pregnancy Loss

We aimed at exploring the value of neutrophil and neutrophil-to-lymphocyte ratio (NLR) as predictive risk markers for recurrent pregnancy loss (RPL) by conducting a retrospective case-control study and a systematic review and meta-analysis. This retrospective case-control study was conducted in an academic hospital from January 2012 to June 2018 and 133 cases of women with RPL and 140 control women. In parallel, we conducted a systematic review and meta-analysis on the value of NLR and neutrophil in RPL risk assessment. Neutrophil and NLR were higher in the women with RPL than those in the controls (median [interquartile range]: 4.32 [3.31-6.18] vs. 3.76 [2.78-4.81], p = 0.001; 2.17 [1.47-3.16] vs. 1.74 [1.40-2.34], p = 0.001). After the cut-off value of the neutrophil and NLR was determined to be 6.3 × 10⁹/L and 3.16, the prevalence of RPL became significantly increased in the high-neutrophil and the high-NLR group compared to the low-neutrophil and the low-NLR group (76.3% vs. 44.2%, p < 0.001; 66.6% vs. 44.5%, p < 0.001). Univariate logistic regression analysis indicated that high-neutrophil and high-NLR were risk factors for RPL, with ORs of 4.06 (95% CI: 1.84-8.95) and 2.49 (95% CI: 1.31-4.71), respectively. Multivariate logistic regression analysis indicated that high-neutrophil was a risk factor for RPL, with OR of 4.91 (95% CI: 1.66-14.50). Meta-analysis of 5 case-control studies (including the present study) indicated that increased neutrophil and NLR may be risk factors for RPL, with SMDs of 0.63 (95% CI: 0.45-0.80) and 0.61 (95% CI: 0.39-0.83). Based on current findings and the meta-analysis, this study indicated that neutrophil and NLR might be valuable for predicting RPL; more studies with large sample are needed to verify this conclusion. The mechanism of the association between neutrophil and RPL needs to be explored in further studies.

Palmitic acid induces inflammation in placental trophoblasts and impairs their migration toward smooth muscle cells through plasminogen activator inhibitor-1

A critical component of early human placental development includes migration of extravillous trophoblasts (EVTs) into the decidua. EVTs migrate toward and displace vascular smooth muscle cells (SMCs) surrounding several uterine structures, including spiral arteries. Shallow trophoblast invasion features in several pregnancy complications including preeclampsia. Maternal obesity is a risk factor for placental dysfunction, suggesting that factors within an obese environment may impair early placental development. Herein, we tested the hypothesis that palmitic acid, a saturated fatty acid circulating at high levels in obese women, induces an inflammatory response in EVTs that hinders their capacity to migrate toward SMCs. We found that SMCs and SMC-conditioned media stimulated migration and invasion of an EVT-like cell line, HTR8/SVneo. Palmitic acid impaired EVT migration and invasion toward SMCs, and induced expression of several vasoactive and inflammatory mediators in EVTs, including endothelin, interleukin (IL)-6, IL-8 and PAI1. PAI1 was increased in plasma of women with early-onset preeclampsia, and PAI1-deficient EVTs were protected from the anti-migratory effects of palmitic acid. Using first trimester placental explants, palmitic acid exposure decreased EVT invasion through Matrigel. Our findings reveal that palmitic acid induces an inflammatory response in EVTs and attenuates their migration through a mechanism involving PAI1. High levels of palmitic acid in pathophysiological situations like obesity may impair early placental development and predispose to placental dysfunction.

Galectin-1-Related Modulation of Trophoblast Endothelial Interactions by Integrins α1 and β1

During normal trophoblast invasion, integrins α6β4 are downregulated, and α1β1 are upregulated in invasive cytotrophoblast cells. In preeclampsia both interstitial and endovascular invasion are shallow and cytotrophoblasts fail to upregulate α1β1 and downregulate α6β4. This study aims to investigate the role of integrins α1β1 and α6β4 on cellular pathways influencing trophoblast integration into endothelial cellular networks in vitro. Red fluorescent-labeled human uterine myometrial microvascular endothelial cells (UtMVECs) were seeded on Matrigel to form endothelial networks. Green fluorescent-labeled trophoblastic HTR-8/SVneo cells pre-incubated with 20 μg/ml of neutralizing antibodies (anti-α1, β1, α6, β4, α1 + β1, or α6 + β4) for 1 h were then co-cultured with endothelial networks with the neutralizing antibodies for 24 h. Fluorescent images were captured, and quantified utilizing Image J. Cells were retrieved to analyze mRNA expression of galectin-1, TIMP-1, and PAI-1 by quantitative PCR. MMP-2, MMP-9, free sFlt-1, and PlGF from conditioned media were measured by ELISA. The integration of trophoblast cells into endothelial cellular networks was inhibited by anti-β1(- 28 ± 3%, p < 0.0001), and increased by anti-α6(+ 19 ± 5%, p < 0.01). Galectin-1 mRNA expression was decreased by anti-α1(- 35 ± 7%, p < 0.001), anti-β1(- 23 ± 5%, p < 0.05), and anti-α1+β1(- 35 ± 5%, p < 0.001). The mRNA expression of TIMP-1 was inhibited by anti-α1(- 59 ± 9%, p < 0.01) and anti-β1(- 63 ± 7%, p < 0.001) while PAI-1 mRNA expression was increased by anti-α1 + β1(+ 285 ± 70%, p < 0.0001). In the conditioned medium, anti-α1 reduced MMP-2(-28 ± 1%, p < 0.001), MMP-9(-27 ± 8%, p < 0.01), and sFlt-1(-27 ± 5%, p < 0.001) production. Anti-β1 reduced MMP-2(- 15 ± 2%, p < 0.05) production. There were no changes in PlGF. Appropriate integrins α1β1 modulate trophoblast cell integration into endothelial cellular networks in vitro through invasive pathways including galectin-1, TIMP-1, PAI-1, MMP-2, and MMP-9 production.

Optimization of lentiviral transduction parameters and its application for CRISPR-based secretome modification of human endometrial mesenchymal stem cells

Mesenchymal stem cells (MSCs) hold a great promise for successful development of regenerative medicine. Among the plenty of uncovered MSCs sources, desquamated endometrium collected from the menstrual blood probably remains the most accessible. Though numerous studies have been published on human endometrium-derived mesenchymal stem cells (hMESCs) properties in the past years, there are only a few data regarding their genetic modulation. Moreover, there is a lack of information about the fate of the transduced hMESCs. The present study aimed to optimize hMESCs transduction parameters and apply Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 technology for genome and secretome modification. The fate of hMESCs transduced either in presence of polybrene (Pb) or protamine sulfate (Ps) was assessed by alterations in CD expression profile, growth rate, cell size, migration capability, osteogenic, adipogenic, and decidual differential potentials. Here, we postulated that the use of Ps for hMESCs genetic manipulations is preferable, as it has no impact on the stem-cell properties, whereas Pb application is undesirable, as it induces cellular senescence. Plasminogen activator inhibitor-1 was selected for further targeted hMESCs genome and secretome modification using CRISPR/Cas9 systems. The obtained data provide optimized transduction scheme for hMESCs and verification of its effectiveness by successful hMESCs genome editing via CRISPR/Cas9 technology.

The interaction effect of angiogenesis and endothelial dysfunction-related gene variants increases the susceptibility of recurrent pregnancy loss

PURPOSE

The role of genetic polymorphisms in the pathogenesis of recurrent pregnancy loss (RPL) has been studied intensively. Complex diseases, including miscarriage, are believed to have a polygenic basis, and gene-gene interactions can play a significant role in the etiology of the disease. This study was conducted to investigate the association of gene-gene interactions with angiogenesis, endothelial dysfunction-related gene polymorphisms, and RPL.

METHODS

A case-control study was conducted with 253 unrelated RPL patients with 2 or more spontaneous pregnancy losses and 339 healthy women with no history of pregnancy complications. Genotyping of single-nucleotide polymorphisms (SNPs) was performed using real-time polymerase chain reaction (real-time PCR), restriction fragment length polymorphism (RFLP), or allele-specific polymerase chain reaction methods.

RESULTS

The genotypes 677TT of the MTHFR gene, 936TT, 936CT, and 634CC, 634GC of the VEGF gene, and allele 894T of the NOS3 gene were associated with a predisposition to RPL in the Russian population. A significant role of additive and epistatic effects in the gene-gene interactions of the SNPs of SERPINE-1, ACE, NOS3, MTHFR, and VEGF genes in RPL was demonstrated.

CONCLUSIONS

The results showed that gene-gene interactions are important for RPL susceptibility. Additionally, analysis of the genotype combinations of several allelic variants provides more information on RPL risk than analysis of independent polymorphic markers.

Thrombophilia and Recurrent Pregnancy Loss: The Enigma Continues

Background

Thrombophilic gene polymorphism is known to be a risk factor for recurrent pregnancy loss (RPL), but few studies have confirmed a possible role of thrombophilic genes polymorphism in RPL risk. This study was conducted to understand the relationship of the mutations of some thrombophilia-associated gene polymorphism (heterozygous/homozygous) with RPL. We compared patients with 2 abortions to patients with 3 or more abortions among Turkish women.

Material/Methods

In this study, patients previously diagnosed with habitual abortus at Obstetrics and Gynecology outpatient clinics in Turkey between 2012 and 2016 were included. In their peripheral blood, we detected factor V Leiden H1299R, prothrombin G20210A, MTHFR C677T, MTHFR A1298C, PAI-1 4G/5G, and PAI-1 4G/4G gene mutations.

Results

In this study, we have observed statistically meaningful data (P<0.01) related to the relationship between RPL and thrombophilia-associated gene polymorphisms such as heterozygous factor V Leiden H1299R, heterozygous prothrombin G20210A, PAI-1 4G/5G, and PAI-1 4G/4G.

Conclusions

We found that diagnosis of thrombophilic genes polymorphism is useful to determine the causes of RPL, recognizing that this multifactorial disease can also be influenced by various acquired factors, including reproduction-associated risk factors and prolonged immobilization.

Genetic association studies of ACE and PAI-1 genes in women with recurrent pregnancy loss

A fine balance between coagulation and fibrinolysis is critical in early pregnancy. Plasminogen activator inhibitor-1 (PAI-1) and angiotensin converting enzyme (ACE) are involved in the fibrinolytic process, and several studies have reported the association between their gene polymorphisms and recurrent pregnancy loss (RPL). This study was conducted to investigate the association between PAI-1 and ACE polymorphisms and idiopathic RPL, using meta-analyses. A systematic review of the published literature from the MEDLINE and EMBASE databases before April 2012 was conducted. Of 209 potentially relevant studies, 22 case-control studies comprising a total of 2,820 RPL patients and 3,009 controls were included. Among these studies were 11 reports of PAI-1 4G/5G and 11 of ACE I/D polymorphisms in patients with RPL. A significant association was found withthe ACE I/D polymorphism [summary odds ratio 1.29 (95% confidence interval 1.02–1.62)] in studies including more than two recurrent abortions. Subgroup analysis did not show significant associations with RPL in Caucasian and non-Caucasian patients. Meta-analyses of PAI-1 4G/5G polymorphism were not found associations with RPL in studies including more than two or three recurrent abortions, and in studies of Caucasian and non-Caucasian patients. In conclusion, meta-analyses showed a significant association between the ACE I/D polymorphism and idiopathic RPL. High clinical heterogeneity existed among studies of PAI-1 4G/5G, and the aggregated data failed to confer higher susceptibility to idiopathic RPL. More well-designed studies with different ethnic populations are required for future integration.

Severe pre-eclampsia is associated with alterations in cytotrophoblasts of the smooth chorion

Pre-eclampsia (PE), which affects ∼8% of first pregnancies, is associated with faulty placentation. Extravillous cytotrophoblasts (CTBs) fail to differentiate properly, contributing to shallow uterine invasion and deficient spiral artery remodeling. We studied the effects of severe PE (sPE) on the smooth chorion portion of the fetal membranes. The results showed a significant expansion of the CTB layer. The cells displayed enhanced expression of stage-specific antigens that extravillous CTBs normally upregulate as they exit the placenta. Transcriptomics revealed the dysregulated expression of many genes (e.g. placental proteins, markers of oxidative stress). We confirmed an sPE-related increase in production of PAPPA1, which releases IGF1 from its binding protein. IGF1 enhanced proliferation of smooth chorion CTBs, a possible explanation for expansion of this layer, which may partially compensate for the placental deficits.

Highlighted article: Cytotrophoblasts (CTBs) within the smooth chorion of the human placenta are implicated in severe pre-eclampsia, undergoing significant expansion and changes in gene expression.

Role of Plasminogen Activator Inhibitor Type 1 in Pathologies of Female Reproductive Diseases

Normal pregnancy is a state of hypercoagulability with diminishing fibrinolytic activity, which is mainly caused by an increase of plasminogen activator inhibitor type 1 (PAI-1). PAI-1 is the main inhibitor of plasminogen activators, including tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA). In human placentas, PAI-1 is expressed in extravillous interstitial trophoblasts and vascular trophoblasts. During implantation and placentation, PAI-1 is responsible for inhibiting extra cellular matrix (ECM) degradation, thereby causing an inhibition of trophoblasts invasion. In the present study, we have reviewed the literature of various reproductive diseases where PAI-1 plays a role. PAI-1 levels are increased in patients with recurrent pregnancy losses (RPL), preeclampsia, intrauterine growth restriction (IUGR), gestational diabetes mellitus (GDM) in the previous pregnancy, endometriosis and polycystic ovary syndrome (PCOS). In general, an increased expression of PAI-1 in the blood is associated with an increased risk for infertility and a worse pregnancy outcome. GDM and PCOS are related to the genetic role of the 4G/5G polymorphism of PAI-1. This review provides an overview of the current knowledge of the role of PAI-1 in reproductive diseases. PAI-1 represents a promising monitoring biomarker for reproductive diseases and may be a treatment target in the near future.

Association between plasminogen activator inhibitor-1 gene polymorphisms and recurrent pregnancy loss: a systematic review and meta-analysis

Human plasminogen activator inhibitor-1 (PAI-1) is closely related to embryonic development and pregnancy success. The association between PAI-1 gene polymorphisms (PAI-1-844G/A and PAI-1-675G/A) and the risk of recurrent pregnancy loss (RPL) is controversial. Therefore, we perform this review to clarify the association between PAI-1 gene polymorphisms and RPL risk. We performed a systematic search for studies that described the effect of PAI-1 polymorphisms on RPL risk. The odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were considered under recessive genetic models. Furthermore, we conducted a subgroup analysis based on the studies' geographic regions of origin. Data were analyzed using Stata 11.2 software. Eighteen studies were included, and a high degree of statistical heterogeneity existed among the studies. In this study, we found a significant association between the PAI-1-675G/A polymorphism and the risk of RPL under the recessive model (OR = 1.70, 95% CI = 1.21-2.38). However, no significant association between the PAI-1-844G/A polymorphism and RPL was noted. PAI-1-675G/A (4G/5G) polymorphisms play a potential role in RPL. The screening of PAI-1 (4G/5G) gene mutations should be included during an RPL diagnostic workup, and patients should be treated using anticoagulant therapy during pregnancy if necessary.

Risk for early pregnancy loss by factor XIII Val34Leu: the impact of fibrinogen concentration

BACKGROUND

We have already described a significantly elevated overall risk for recurrent pregnancy loss (RPL) in women carrying the coagulation factor XIII (FXIII) Val34Leu and/or the plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism assuming that these polymorphisms contribute synergistically to RPL because of impaired hypofibrinolysis. Recent studies on FXIII indicate that the impact of the FXIII 34Leu genotype on fibrin structure and fibrinolysis is affected by fibrinogen concentration. Therefore, we reinvestigated the association between fibrinogen concentrations and FXIII Val34Leu with early RPL.

MATERIALS AND METHODS

In this case-control study, we enrolled 49 women with a history of two consecutive or three to six nonconsecutive pregnancy losses between the 8th and 12th week of gestation and 48 healthy controls. The risk for RPL in carriers of FXIII 34Leu at fibrinogen levels above or below the median and first tertile of controls was evaluated.

RESULTS

In carriers of the 34Leu allele, fibrinogen levels below the median (i.e., ≤ 300 mg/dl) and the first tertile (i.e., ≤ 284 mg/dl) of controls were associated with an increased risk for RPL [(2.9 (1.1-7.7), 3.9(1.0-15.0)].

CONCLUSIONS

The FXIII Val34Leu polymorphism may be associated with the development of early RPL in association with fibrinogen concentrations. At fibrinogen levels in the low normal range, FXIII 34Leu may modify fibrin structure toward an increased resistance to fibrinolysis.

Transformation of a transposon into a derived prolactin promoter with function during human pregnancy

Transposable elements (TEs) are known to provide DNA for host regulatory functions, but the mechanisms underlying the transformation of TEs into cis-regulatory elements are unclear. In humans two TEs--MER20 and MER39--contribute the enhancer/promoter for decidual prolactin (dPRL), which is dramatically induced during pregnancy. We show that evolution of the strong human dPRL promoter was a multistep process that took millions of years. First, MER39 inserted near MER20 in the primate/rodent ancestor, and then there were two phases of activity enhancement in primates. Through the mapping of causal nucleotide substitutions, we demonstrate that strong promoter activity in apes involves epistasis between transcription factor binding sites (TFBSs) ancestral to MER39 and derived sites. We propose a mode of molecular evolution that describes the process by which MER20/MER39 was transformed into a strong promoter, called "epistatic capture." Epistatic capture is the stabilization of a TFBS that is ancestral but variable in outgroup lineages, and is fixed in the ingroup because of epistatic interactions with derived TFBSs. Finally, we note that evolution of human promoter activity coincides with the emergence of a unique reproductive character in apes, highly invasive placentation. Because prolactin communicates with immune cells during pregnancy, which regulate fetal invasion into maternal tissues, we speculate that ape dPRL promoter activity evolved in response to increased invasiveness of ape fetal tissue.

The evolution of menstruation: a new model for genetic assimilation: explaining molecular origins of maternal responses to fetal invasiveness

Why do humans menstruate while most mammals do not? Here, we present our answer to this long-debated question, arguing that (i) menstruation occurs as a mechanistic consequence of hormone-induced differentiation of the endometrium (referred to as spontaneous decidualization, or SD); (ii) SD evolved because of maternal-fetal conflict; and (iii) SD evolved by genetic assimilation of the decidualization reaction, which is induced by the fetus in non-menstruating species. The idea that menstruation occurs as a consequence of SD has been proposed in the past, but here we present a novel hypothesis on how SD evolved. We argue that decidualization became genetically stabilized in menstruating lineages, allowing females to prepare for pregnancy without any signal from the fetus. We present three models for the evolution of SD by genetic assimilation, based on recent advances in our understanding of the mechanisms of endometrial differentiation and implantation. Testing these models will ultimately shed light on the evolutionary significance of menstruation, as well as on the etiology of human reproductive disorders like endometriosis and recurrent pregnancy loss.

Biochemistry of HELLP syndrome

The HELLP syndrome is a serious complication of pregnancy characterized by hemolysis (H), elevated liver (EL) enzymes, and low platelet (LP) count that occurs in 0.2-0.6% of all pregnancies and in 10-20% of cases with severe preeclampsia and frequently leads to adverse maternal and perinatal outcome. The exact pathobiology of HELLP syndrome has not been clearly defined. As it is considered a form or a complication of severe preeclampsia, it likely has its origin in aberrant placental development and function resulting in ischemia-producing oxidative stress. However, there is still a debate on whether HELLP must be considered a severe form of preeclampsia or a separate disease entity. It can be described as a placenta-induced disease, as is preeclampsia itself, but with a more acute and predominant inflammatory process typically targeting the liver and with a greater activation of the coagulation system. This occurs during a disordered immunologic process and may be due to a genetic predisposition. In this review, we discuss the main biochemical characteristics of HELLP syndrome, particularly focusing on molecular aspects of placental involvement and maternal systemic responses.

Transient reduction of placental angiogenesis in PAI-1-deficient mice

Murine placentation is associated with the invasion of maternal endometrium by trophoblasts and an extensive maternal and fetal angiogenesis. Plasminogen activator inhibitor-1 (PAI-1) is transiently produced by spongiotrophoblasts and trophoblast giant cells at 10.5-11.5 days postcoitum (dpc). Knowing the key contribution of PAI-1 in the regulation of angiogenesis, we have now analyzed the consequence of PAI-1 deficiency on murine placentation. Morphological and quantitative computer-assisted image analysis revealed abnormal placental morphology in PAI-1-/- mice at 10.5 and 12.5 dpc. At 10.5 dpc, the genetic ablation of PAI-1 resulted in a transient reduction of both maternal and fetal vascularizations in the placenta and increased trophoblast cell density. This was associated with a poorer development of the labyrinth and an extension of the decidua. A larger spongiotrophoblast layer appeared at 12.5 dpc in PAI-1-deficient mice. Placental morphology was normalized at 14.5 dpc. Microarray analyses performed on laser capture microdissected labyrinths revealed that 46 genes were differentially expressed between the two genotypes at 10.5 dpc. However, only 11 genes were still differently modulated at 14.5 dpc, when normalization of placental morphology had taken place. This transcriptomic profiling highlighted a dysregulation in the expression of placenta-related cathepsin family members. Altogether our data provide evidence for a transient impaired placental morphology in PAI-1-deficient mice that is then normalized, leading to normal embryonic development.

Placental expression of proteases and their inhibitors in patients with HELLP syndrome

In preeclampsia and hemolysis, elevated liver enzymes and low platelet (HELLP) syndrome, impaired trophoblast invasion and excessive fibrin deposition in the placental intervillous space is associated with fetal compromise. However, little information is available whether modulation of placental protease expression--potentially causing impaired trophoblast invasion--is associated with the HELLP syndrome. Total RNA and protein were extracted from placental tissue from 11 females with HELLP syndrome and 8 controls matched for gestational age. mRNA expression of matrix metalloprotease (MMP) -2 and -9, tissue inhibitors of metalloprotease (TIMP) -1, -2, and -3, and urokinase-type plasminogen activator receptor (uPAR) was determined by Northern blotting. Protein expression of MMP-2 and -9, and TIMP-1 and -2 was detected by Western blotting and that of uPA, uPAR, and plasminogen activator inhibitor (PAI) -1 by ELISA. In patients with HELLP syndrome, mRNA expression of MMP-2 and TIMP-2 was decreased, whereas TIMP-1 and -3 levels were unchanged. MMP-9 and uPAR mRNA was undetectable in both groups. Protein expression of all investigated proteolytic factors remained unchanged. Our findings at the mRNA level suggest a decrease in matrix remodeling in placentae from patients with HELLP syndrome compared with control pregnancies, although this is not supported at the protein level.

Beyond oxygen: complex regulation and activity of hypoxia inducible factors in pregnancy

In the first trimester the extravillous cytotrophoblast cells occlude the uterine spiral arterioles creating a low oxygen environment early in pregnancy, which is essential for pregnancy success. Paradoxically, shallow trophoblast invasion and defective vascular remodelling of the uterine spiral arteries in the first trimester may result in impaired placental perfusion and chronic placental ischemia and hypoxia later in gestation leading to adverse pregnancy outcomes. The hypoxia inducible factors (HIFs) are key mediators of the response to low oxygen. We aimed to elucidate mechanisms of regulation of HIFs and the role these may play in the control of placental differentiation, growth and function in both normal and pathological pregnancies. The Pubmed database was consulted for identification of the most relevant published articles. Search terms used were oxygen, placenta, trophoblast, pregnancy, HIF and hypoxia. The HIFs are able to function throughout all aspects of normal and abnormal placental differentiation, growth and function; during the first trimester (physiologically low oxygen), during mid-late gestation (where there is adequate supply of blood and oxygen to the placenta) and in pathological pregnancies complicated by placental hypoxia/ischemia. During normal pregnancy HIFs may respond to complex alterations in oxygen, hormones, cytokines and growth factors to regulate placental invasion, differentiation, transport and vascularization. In the ever-changing environment created during pregnancy, the HIFs appear to act as key mediators of placental development and function and thereby are likely to be important contributors to both normal and adverse pregnancy outcomes.

A prospective case-control study analyzes 12 thrombophilic gene mutations in Turkish couples with recurrent pregnancy loss

PROBLEM

Recurrent pregnancy loss (RPL) is a heterogeneous disorder. The contribution of specific thrombophilic genes to the pathophysiology of RPL has remained controversial. We evaluated the prevalences of 12 thrombophilic gene mutations among homogenous Caucasian couples with RPL and fertiles.

METHOD

of study This was a prospective case-control study evaluating 272 women with RPL and 152 of their male partners, and a control group of 56 fertile couples. We investigated mutations including FV Leiden, factor V H1299R, factor II prothrombin G20210A, F XIII V34L, beta-fibrinogen -455G>A, plasminogen activator inhibitor-1, GPIIIa L33P (HPA-1 a/b L33P), MTHFR C677T, MTHFR A1298C, ACE I/D, Apo B R3500Q, and Apo E.

RESULTS

Overall, heterozygous mutations of FV Leiden, FXIII V34L, GPIIIa L33P, Apo E4, and prothrombin G20210A and homozygous mutations of PAI-1and MTHFR C677T were associated with RPL. There was no meaningful association between RPL and other studied genes.

CONCLUSION

In contrast to the other mutations and polymorphisms, FV Leiden, FXIII V34L, GPIIIa L33P, Apo E, prothrombin G20210A, PAI-1 and MTHFR C677T gene mutations may help to identify the couples at risk for recurrent pregnancy loss.

mTOR mediates human trophoblast invasion through regulation of matrix-remodeling enzymes and is associated with serine phosphorylation of STAT3

The intracellular signaling molecule mammalian target of rapamycin (mTOR) is essential for cell growth and proliferation. It is involved in mouse embryogenesis, murine trophoblast outgrowth and linked to tumor cell invasiveness. In order to assess the role of mTOR in human trophoblast invasion we analyzed the in vitro invasiveness of HTR-8/SVneo immortalized first-trimester trophoblast cells in conjunction with enzyme secretion upon mTOR inhibition and knockdown of mTOR protein expression. Additionally, we also tested the capability of mTOR to trigger signal transducer and activator of transcription (STAT)-3 by its phosphorylation status. Rapamycin inhibited mTOR kinase activity as demonstrated with a lower phosphorylation level of the mTOR substrate p70 S6 kinase (S6K). With the use of rapamycin and siRNA-mediated mTOR knockdown we could show that cell proliferation, invasion and secretion of matrix-metalloproteinases (MMP)-2 and -9, urokinase-like plasminogen activator (uPA) and its major physiological uPA inhibitor (PAI)-1 were inhibited. While tyrosine phosphorylation of STAT3 was unaffected by mTOR inhibition and knockdown, serine phosphorylation was diminished. We conclude that mTOR signaling is one major mechanism in a tightly regulated network of intracellular signal pathways including the JAK/STAT system to regulate invasion in human trophoblast cells by secretion of enzymes that remodel the extra-cellular matrix (ECM) such as MMP-2, -9, uPA and PAI-1. Dysregulation of mTOR may contribute to pregnancy-related pathologies caused through impaired trophoblast invasion.

Endometrial gene expression in early pregnancy: lessons from human ectopic pregnancy

Human endometrium undergoes modifications in preparation for embryonic implantation. This study investigated in vivo the endocrine effects of pregnancy on the endometrium, using the model of ectopic pregnancy. Endometrial biopsies from 9 subjects with ectopic pregnancy (Preg) were compared with 8 and 6 samples of mid and late secretory endometrium, respectively. After hybridizing with Affymetrix HGU133 Plus 2 chips, data were analyzed using GeneSpring GX and Ingenuity Pathways Analysis. From 54,675 genes, 3021 genes were significantly differentiated when mid-secretory endometrium was compared with the Preg (Volcano plot; P < .05, >or=2-fold change).The complement and coagulation cascade, phospholid degradation, glycosphingolipid biosynthesis (globoseries), retinol metabolism, antigen presentation pathway, glycosphingolipid biosynthesis, and O-glycan biosynthesis were main significant canonical pathways found in Preg samples. Validation was done with reverse transcriptase polymerase chain reaction. In conclusion, the ectopic embryo has a significant impact, by an endocrine mechanism, on endometrium, when compared with the window of implantation.

Immunobiology of gestational trophoblastic diseases

Gestational trophoblastic diseases (GTDs) comprise a group of interrelated diseases characterized by development after gestation, widespread metastases, and high curability with chemotherapy. The good prognosis of GTDs is considered partly a result of the host immune response to paternal antigens expressed on trophoblastic cells. In this study, we review current understanding of the immunobiology of GTDs. First of all, we describe the microenvironment between trophoblastic cells and subpopulation of immune cells. Second, immunogenetics, immune microenvironment around abnormal trophoblast, and mechanism of GTDs escaping from maternal immune system surveillance were also discussed. Third, we propose the possible immunotherapy for persistent GTDs, particularly the vaccine designed on human chorionic gonadotrophin, which is generally accepted as a tumor marker for GTDs diagnosis. Due to the low incidence of GTDs and high response to chemotherapy, there have been few literatures about immunobiologic characteristics of GTDs compared with the other gynecologic malignancies, such as ovarian cancer, but the immunologic behavior of GTDs should be explored for further understanding of the etiology of these diseases and to help designing immunotherapeutic strategies for persistent GTDs.

Lack of site-specific production of decidual alpha-2 macroglobulin in human pregnancy

BACKGROUND

Alpha-2 Macroglobulin (A2M) is a protease inhibitor that is present in both human and rat decidual tissue. In mice, decidual A2M prevents excessive trophoblastic invasion; however, its role in human decidual tissue is unknown. It is possible that A2M may also influence trophoblast invasion in human pregnancy, which would be reflected in increased A2M production in decidua basalis. The aim of the current study was to determine and compare A2M production from first trimester human decidua basalis and decidua parietalis.

METHODS

Human decidual tissues were obtained from patients undergoing surgical termination at 9 to 12 gestational weeks. Strips of decidua basalis and decidua parietalis were obtained by uterine curettage under real-time ultrasound guidance. Tissue samples were fixed in 10% formalin or snap-frozen for immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, respectively. Protein and mRNA production between the two sites were compared using the Mann-Whitney U test.

RESULTS

Paired basal and parietal decidua were analyzed by immunohistochemistry (n = 9) and by RT-PCR (n = 10). There was no significant difference in A2M mRNA expression between decidua basalis and decidua parietalis (P = .5). Immunohistochemical staining intensity for A2M protein was significantly higher in basalis than in parietalis (P = .004), but the extent of positively stained cells were not significantly different (P = .051). Strong A2M staining in decidua basalis was mainly localized in the intracellular storage vesicles, which may suggest a role of A2M in this site.

CONCLUSIONS

We conclude that the expression pattern of A2M in human decidua basalis and decidua parietalis is not consistent with an important role of this gene during the observed gestational period. Contrary to its role in rodent implantation, A2M is probably not involved in regulating human implantation and trophoblastic invasion during this gestational window frame.

The myofibroblast is the predominant plasminogen activator inhibitor-1-expressing cell type in human breast carcinomas

The tumor level of plasminogen activator inhibitor-1 (PAI-1) is an informative biochemical marker of a poor prognosis in several cancer types. However, the tumor biological functions of PAI-1 and the identity of PAI-1-expressing cells are controversial. With the aim of immunohistochemically localizing PAI-1 in formalin-fixed, paraffin-embedded invasive ductal breast carcinoma samples, we raised new polyclonal antibodies against PAI-1 from different expression systems. The antibodies were affinity purified by absorption on immobilized preparations of PAI-1 different from those used for immunization. The specificity of the antibodies was ensured by immunoblotting analysis. In immunohistochemistry, the staining pattern obtained with the antibodies showed a good correlation with the PAI-1 mRNA expression pattern. In all 25 cases analyzed, PAI-1 immunoreactivity was predominantly localized in fibroblast-like cells. Double-immunofluorescence analyses showed co-expression of PAI-1 and alpha-smooth muscle actin in these cells, suggesting that they are myofibroblasts. PAI-1 was also seen in some myoepithelial cells surrounding occasional foci of ductal carcinoma in situ (9 of 25), some endothelial cells (8 of 25), some cancer cells (3 of 25), and some mast cells (6 of 25). In conclusion, we have provided a robust immunohistochemical procedure for detection of PAI-1 and shown that the majority of the PAI-1-expressing cells in invasive ductal breast carcinomas are myofibroblasts.

Evidence of a limited contribution of feto-maternal interactions to trophoblast differentiation along the invasive pathway

Trophoblast differentiation is a key event in human placental development. During extravillous trophoblast (EVT) differentiation, stem cells from the anchoring villi detach from their basement membrane and proliferate to form aggregates called trophoblast cell columns (TCCs). They subsequently invade the decidua and differentiate into interstitial and endovascular trophoblasts. The influence of the decidua on EVT differentiation is controversial. We therefore compared the pattern of trophoblast differentiation marker expression in viable intrauterine and tubal pregnancies, as decidual cell markers (prolactin [PRL] and insulin-like growth factor binding Protein-1 [IGFBP1]) were only expressed in endometrial implantation sites. Extravillous trophoblast differentiation in anchoring villi from uterine and ectopic pregnancies exhibited a comparable phenotypical switch: alpha6 integrin subunit, E-cadherin, EGF receptor, Ki 67 and connexin 40 were localized in the proximal part of the TCC, while alpha5beta1 and alpha1 integrins, c-erb B2, hPL and HLA-G were expressed by invasive cytotrophoblasts. The cyclin-dependent kinase inhibitors p16 and p57 were mainly detected in invasive cytotrophoblasts some distance from the columns. However, the TCC was markedly longer in tubal pregnancy than in intrauterine pregnancy. These findings suggest that the decidua is not necessary to trigger EVT invasion, but that it is likely to limit the extent of the TCC and to accelerate the onset of EVT migration.

Urokinase receptor is up-regulated in endothelial cells and macrophages associated with fibrinoid deposits in the human placenta

Clearance of fibrin deposits within the human placenta is an ongoing process during normal placental development. Plasminogen is a circulating fibrinolytic protease zymogen activated in situ by plasminogen activators. We have previously reported that the receptor for urokinase plasminogen activator (uPAR) is expressed by cells either covering or enmeshed within the perivillous fibrinoid deposits. Whereas these cells seemed likely to be trophoblasts, a definitive identification was lacking, and this question is central to the understanding of the cellular mechanisms directing fibrinolysis in the placenta. In this study we have performed immunohistochemical co-localization studies and found that the uPAR-positive cells covering fibrinoid deposits are immunoreactive for CD31 and vWF, indicating that they are actually endothelial cells. In addition, we found that perivillous fibrinoid deposits not covered with uPAR-positive endothelial cells were covered with platelets identified by integrin alpha(IIb)beta(3)-immunoreactivity. Also surprisingly, the uPAR-positive cells enmeshed within fibrinoid deposits express a cell specific marker indicating that they are macrophages. Both uPAR-positive cell populations also express uPA immunoreactivity. Taken together, the data suggest that both fibrinoid-covering endothelial cells and fibrinoid-enmeshed macrophages can participate in the clearance process of perivillous fibrinoid deposits formed in the human placenta.

Plasminogen activator inhibitor 1 4G/5G polymorphism and coagulation factor XIII Val34Leu polymorphism: impaired fibrinolysis and early pregnancy loss

BACKGROUND

A successful outcome of pregnancy depends on proper placental formation. In the very beginning of this process, trophoblast invasion and fibrin deposition into the wall of the decidual veins play an important part. Two polymorphisms, coagulation factor XIII (FXIII) Val34Leu and plasminogen activator inhibitor 1 (PAI-1) 4G/5G, interfere with fibrin cross-linking and regulation of fibrinolysis and may therefore contribute to early pregnancy loss.

METHODS

We enrolled 49 unrelated Caucasian women with a history of two consecutive or three to six nonconsecutive early pregnancy losses and 48 unrelated parous healthy controls without a history of pregnancy loss and evaluated them for the following genetic variants: the factor V Leiden and prothrombin G20210A gene mutations, the methylenetetrahydrofolate reductase C677T and A1298C polymorphisms, and the PAI-1 4G/5G and FXIII Val34Leu polymorphisms.

RESULTS

For the isolated occurrence of PAI-1 4G/5G or FXIII Val34Leu, we found no statistically significant difference between cases and controls. For homozygosity of either or compound carrier status of both mutations, the overall relative risk for early pregnancy loss was significantly increased (odds ratio = 2.4; 95% confidence interval, 1.1-5.5; P = 0.032). We observed no statistically relevant association of any of the other tested mutations with early pregnancy loss.

CONCLUSION

Homozygosity for PAI-1 4G or FXIII 34Leu polymorphisms as well as compound carrier status is associated with early pregnancy loss.

Quantitative evaluation of the influence of ovarian steroids on plasminogen activators and inhibitors in human endometrial cells and trophoblasts

INTRODUCTION

Plasminogen activators and inhibitors were quantitated in cultured human endometrial and trophoblast cells under the influence of ovarian steroids in order to investigate the role of the fibrinolytic system for trophoblast invasion and anchorage.

MATERIALS AND METHODS

Plasminogen activators (t-PA and u-PA) and their inhibitors (PAI-1 and PAI-2) secretions were assayed in cultures of epithelial, stromal, and trophoblast cells. These cells were also cultured on a fibrin substrate for microscopic examination of the fibrinolytic degradation.

RESULTS

The u-PA from epithelial cells was predominant among PAs and PAI-1 in endometrial cells. Estradiol (E2) enhanced t-PA production in stromal cells and PAI-1 production in epithelial cells. Progesterone (P4) suppressed u-PA production in epithelial cells and enhanced PAI-1 production in both epithelial and stromal cells. Trophoblasts produced PAI-1, PAI-2, and small quantities of t-PA and u-PA, none of which were notably influenced by E2 or P4. The PAI-1 production in trophoblasts was more than four-fold greater than the u-PA production in epithelial cells. Epithelial and stromal cells initially grew on fibrin substrate but were gradually detached from the substrate with fibrinolytic degradation, with the exception of the stromal cells grown in the presence of P4 (or E2+P4). Trophoblasts grew well on fibrin substrate without fibrinolytic degradation both in the presence and absence of the steroids tested.

CONCLUSIONS

Fibrinolytic balance seemed to be basically maintained between the endometrial PAs and the relative excess of trophoblasts-derived PAI-1. This balance might be regulated principally by P4 and focally by E2 in the endometrial tissue for placental implantation.