CXCR3 Polymorphism and Expression Associate with Spontaneous Preterm Birth

Maternal serum alpha-1 antitrypsin levels in spontaneous preterm and term pregnancies

Currently, there are no accurate means to predict spontaneous preterm birth (SPTB). Recently, we observed low expression of alpha-1 antitrypsin (AAT) in SPTB placentas. Present aim was to compare the concentrations of maternal serum AAT in pregnancies with preterm and term deliveries. Serum C-reactive protein (CRP) was used as a reference inflammatory marker. Two populations were studied. The first population comprised women who eventually gave birth spontaneously preterm (SPTB group) or term (control group). The second population included pregnant women shortly before delivery and nonpregnant women. We observed that serum AAT levels were higher in the SPTB group than in the controls, and a similar difference was observed when serum CRP was considered in multivariable analysis. However, the overlap in the AAT concentrations was considerable. No statistical significance was observed in serum AAT levels between preterm and term pregnancies at delivery. However, AAT levels were higher at delivery compared to nonpregnant controls. We did not observe a strong correlation between serum AAT and CRP in early pregnancy samples and at labor. We propose that during early pregnancy, complicated by subsequent SPTB, modest elevation of serum AAT associates with SPTB.

Interferon-stimulated gene 15 polymorphisms are associated with spontaneous preterm birth in Taiwanese women

PROBLEM

Immune and inflammatory responses are known to be major causes of preterm birth (PTB). The maternal genetic background plays an important role in the development of PTB. Interferon-stimulated gene 15 (ISG15) is an interferon-induced protein which can modulate immune cell activation and function. We aim to study if polymorphisms in the ISG15 gene are associated with spontaneous PTB (sPTB) risk in Taiwanese women.

METHOD OF STUDY

ISG15 rs4615788 C/G, rs1921 G/A, and rs8997 A/G polymorphisms were genotyped in a hospital-based study of 112 women with sPTB and 1120 term controls. The plasma concentrations of ISG15 were determined by enzyme-linked immunosorbent assay.

RESULTS

We found the ISG15 rs1921 G-rs8997 A haplotype was associated with decreased risk for PTB (χ2  = 6.26, p = .01, pc  = .04). The A/G genotype of ISG15 rs8997 polymorphism might have the potential to confer reduced risk of PTB women (χ2  = 4.09, p = .04, pc  = .08). Spontaneous PTB women displayed higher plasma ISG15 levels compared to term controls (p < .001). The plasma ISG15 levels among pregnant women with rs8997 A/G genotype were found significantly lower compared to G/G genotype (p = .03).

CONCLUSIONS

Women with the ISG15 rs1921 G-rs8997 A haplotype may associate with spontaneous PTB. These findings provide new insights into the etiology of preterm birth.

Integrated Bioinformatics Analysis to Screen Hub Gene Signatures for Fetal Growth Restriction

Background. Fetal growth restriction (FGR) is the impairment of the biological growth potential of the fetus and often leads to adverse pregnancy outcomes. The molecular mechanisms for the development of FGR, however, are still unclear. The purpose of this study is to identify critical genes associated with FGR through an integrated bioinformatics approach and explore the potential pathogenesis of FGR. Methods. We downloaded FGR-related gene microarray data, used weighted gene co-expression network analysis (WGCNA), differentially expressed genes (DEGs), and protein-protein interaction (PPI) networks to screen hub genes. The GSE24129 gene set was used for validation of critical gene expression levels and diagnostic capabilities. Results. A weighted gene co-expression network was constructed, and 5000 genes were divided into 12 modules. Of these modules, the blue module showed the closest relationship with FGR. Taking the intersection of the DEGs and genes in the blue module as pivotal genes, 277 genes were identified, and 20 crucial genes were screened from the PPI network. The GSE24129 gene set verified the expression of 20 genes, and CXCL9, CXCR3, and ITGAX genes were identified as actual pivotal genes. The expression levels of CXCL9, CXCR3, and ITGAX were increased in both the training and validation sets, and ROC curve validation revealed that these three pivotal genes had a significant diagnostic ability for FGR. Single-gene GSEA results showed that all three core genes activated “hematopoietic cell lineage” and “cell adhesion molecules” and inhibited the “cGMP-PKG signaling pathway” in the development of FGR. CXCL9, CXCR3, and ITGAX may therefore be closely associated with the development of FGR and may serve as potential biomarkers for the diagnosis and treatment of FGR.

Elevated human placental heat shock protein 5 is associated with spontaneous preterm birth

BACKGROUND

Specific heat shock proteins are associated with pregnancy complications, including spontaneous preterm birth (SPTB). Placental proteomics and whole exome sequencing recently suggested an association between heat shock protein HSPA5 and uncomplicated SPTB. In the present study, we investigated the localization of and possible roles for HSPA5 in SPTB.

METHODS

Western blot was performed to validate the result from the previously published proteomic analysis. We used qPCR to assess mRNA expression of genes and immunohistochemistry and immunoelectron microscopy to examine localization of HSPA5 in placental tissue. We silenced the HSPA5 gene in the HTR8/SVneo human trophoblast cell line to investigate possible functions of HSPA5.

RESULTS

HSPA5 was upregulated in placentas from SPTBs compared to spontaneous term births. We did not observe upregulation of HSPA5 mRNA in placental samples. The protein was localized in placental trophoblast in both spontaneous preterm and term placentas. Gene silencing of HSPA5 in human trophoblast cell culture affected the inflammatory response and decreased the expression of several proinflammatory genes.

CONCLUSIONS

We suggest that upregulation of HSPA5 in the placenta is associated with spontaneous preterm labor. HSPA5 may promote the inflammatory response and alter the anti-inflammatory state of the placenta which could eventually lead to premature labor.

IMPACT

We validated upregulation of HSPA5 in placentas from spontaneous preterm birth. HSPA5 was not upregulated at transcriptional level which suggests that it may be regulated post-translationally. Silencing HSPA5 in a human trophoblast-derived cell line suggested that HSPA5 promotes expression of proinflammatory cytokines. The emerging inflammation could lead to spontaneous preterm labor. Identifying inflammatory pathways and factors associated with spontaneous preterm birth increases knowledge of the molecular mechanisms of premature labor. This could provide cues to predict imminent premature labor and lead to information about how to safely maintain pregnancies.

Genetics, epigenetics, and transcriptomics of preterm birth

Preterm birth contributes significantly to neonatal mortality and morbidity. Despite its global significance, there has only been limited progress in preventing preterm birth. Spontaneous preterm birth (sPTB) results from a wide variety of pathological processes. Although many non-genetic risk factors influence the timing of gestation and labor, compelling evidence supports the role of substantial genetic and epigenetic influences and their interactions with the environment contributing to sPTB. To investigate a common and complex disease such as sPTB, various approaches such as genome-wide association studies, whole-exome sequencing, transcriptomics, and integrative approaches combining these with other 'omics studies have been used. However, many of these studies were typically small or focused on a single ethnicity or geographic region with limited data, particularly in populations at high risk for sPTB, or lacked a robust replication. These studies found many genes involved in the inflammation and immunity-related pathways that may affect sPTB. Recent studies also suggest the role of epigenetic modifications of gene expression by the environmental signals as a potential contributor to the risk of sPTB. Future genetic studies of sPTB should continue to consider the contributions of both maternal and fetal genomes as well as their interaction with the environment.

Human placental proteomics and exon variant studies link AAT/SERPINA1 with spontaneous preterm birth

BACKGROUND

Preterm birth is defined as live birth before 37 completed weeks of pregnancy, and it is a major problem worldwide. The molecular mechanisms that lead to onset of spontaneous preterm birth are incompletely understood. Prediction and evaluation of the risk of preterm birth is challenging as there is a lack of accurate biomarkers. In this study, our aim was to identify placental proteins that associate with spontaneous preterm birth.

METHODS

We analyzed the proteomes from placentas to identify proteins that associate with both gestational age and spontaneous labor. Next, rare and potentially damaging gene variants of the identified protein candidates were sought for from our whole exome sequencing data. Further experiments we performed on placental samples and placenta-associated cells to explore the location and function of the spontaneous preterm labor-associated proteins in placentas.

RESULTS

Exome sequencing data revealed rare damaging variants in SERPINA1 in families with recurrent spontaneous preterm deliveries. Protein and mRNA levels of alpha-1 antitrypsin/SERPINA1 from the maternal side of the placenta were downregulated in spontaneous preterm births. Alpha-1 antitrypsin was expressed by villous trophoblasts in the placenta, and immunoelectron microscopy showed localization in decidual fibrinoid deposits in association with specific extracellular proteins. siRNA knockdown in trophoblast-derived HTR8/SVneo cells revealed that SERPINA1 had a marked effect on regulation of the actin cytoskeleton pathway, Slit-Robo signaling, and extracellular matrix organization.

CONCLUSIONS

Alpha-1 antitrypsin is a protease inhibitor. We propose that loss of the protease inhibition effects of alpha-1 antitrypsin renders structures critical to maintaining pregnancy susceptible to proteases and inflammatory activation. This may lead to spontaneous premature birth.

Management Practices During Perinatal Respiratory Transition of Very Premature Infants

The present review considers some controversial management practices during extremely premature perinatal transition. We focus on perinatal prevention and treatment of respiratory distress syndrome (RDS) in immature infants. New concerns regarding antenatal corticosteroid management have been raised. Many fetuses are only exposed to potential adverse effects of the drug. Hence, the formulation and the dosage may need to be modified. Another challenge is to increase the fraction of the high-risk fetuses that benefit from the drug and to minimize the harmful effects of the drug. On the other hand, boosting anti-inflammatory and anti-microbial properties of surfactant requires further attention. Techniques of prophylactic surfactant administration to extremely immature infants at birth may be further refined. Also, new findings suggest that prophylactic treatment of patent ductus arteriosus (PDA) of a high-risk population rather than later selective closure of PDA may be preferred. The TREOCAPA trial (Prophylactic treatment of the ductus arteriosus in preterm infants by acetaminophen) evaluates, whether early intravenous paracetamol decreases the serious cardiorespiratory consequences following extremely premature birth. Lastly, is inhaled nitric oxide (iNO) used in excess? According to current evidence, iNO treatment of uncomplicated RDS is not indicated. Considerably less than 10% of all very premature infants are affected by early persistence of pulmonary hypertension (PPHN). According to observational studies, effective ventilation combined with early iNO treatment are effective in management of this previously fatal disease. PPHN is associated with prolonged rupture of fetal membranes and birth asphyxia. The lipopolysaccharide (LPS)-induced immunotolerance and hypoxia-reperfusion-induced oxidant stress may inactivate NO-synthetases in pulmonary arterioles and terminal airways. Prospective trials on iNO in the management of PPHN are indicated. Other pulmonary vasodilators may be considered as comparison drugs or adjunctive drugs. The multidisciplinary challenge is to understand the regulation of pregnancy duration and the factors participating the onset of extremely premature preterm deliveries and respiratory adaptation. Basic research aims to identify deficiencies in maternal and fetal tissues that predispose to very preterm births and deteriorate the respiratory adaptation of immature infants. Better understanding on causes and prevention of extremely preterm births would eventually provide effective antenatal and neonatal management practices required for the intact survival.

Integrative genetic, genomic and transcriptomic analysis of heat shock protein and nuclear hormone receptor gene associations with spontaneous preterm birth

Heat shock proteins are involved in the response to stress including activation of the immune response. Elevated circulating heat shock proteins are associated with spontaneous preterm birth (SPTB). Intracellular heat shock proteins act as multifunctional molecular chaperones that regulate activity of nuclear hormone receptors. Since SPTB has a significant genetic predisposition, our objective was to identify genetic and transcriptomic evidence of heat shock proteins and nuclear hormone receptors that may affect risk for SPTB. We investigated all 97 genes encoding members of the heat shock protein families and all 49 genes encoding nuclear hormone receptors for their potential role in SPTB susceptibility. We used multiple genetic and genomic datasets including genome-wide association studies (GWASs), whole-exome sequencing (WES), and placental transcriptomics to identify SPTB predisposing factors from the mother, infant, and placenta. There were multiple associations of heat shock protein and nuclear hormone receptor genes with SPTB. Several orthogonal datasets supported roles for SEC63, HSPA1L, SACS, RORA, and AR in susceptibility to SPTB. We propose that suppression of specific heat shock proteins promotes maintenance of pregnancy, whereas activation of specific heat shock protein mediated signaling may disturb maternal–fetal tolerance and promote labor.

Human CPPED1 belongs to calcineurin-like metallophosphoesterase superfamily and dephosphorylates PI3K-AKT pathway component PAK4

Protein kinases and phosphatases regulate cellular processes by reversible phosphorylation and dephosphorylation events. CPPED1 is a recently identified serine/threonine protein phosphatase that dephosphorylates AKT1 of the PI3K-AKT signalling pathway. We previously showed that CPPED1 levels are down-regulated in the human placenta during spontaneous term birth. In this study, based on sequence comparisons, we propose that CPPED1 is a member of the class III phosphodiesterase (PDE) subfamily within the calcineurin-like metallophosphoesterase (MPE) superfamily rather than a member of the phosphoprotein phosphatase (PPP) or metal-dependent protein phosphatase (PPM) protein families. We used a human proteome microarray to identify 36 proteins that putatively interact with CPPED1. Of these, GRB2, PAK4 and PIK3R2 are known to regulate the PI3K-AKT pathway. We further confirmed CPPED1 interactions with PAK4 and PIK3R2 by coimmunoprecipitation analyses. We characterized the effect of CPPED1 on phosphorylation of PAK4 and PIK3R2 in vitro by mass spectrometry. CPPED1 dephosphorylated specific serine residues in PAK4, while phosphorylation levels in PIK3R2 remained unchanged. Our findings indicate that CPPED1 may regulate PI3K-AKT pathway activity at multiple levels. Higher CPPED1 levels may inhibit PI3K-AKT pathway maintaining pregnancy. Consequences of decreased CPPED1 expression during labour remain to be elucidated.

A Regulatory Role of Chemokine Receptor CXCR3 in the Pathogenesis of Chronic Obstructive Pulmonary Disease and Emphysema

Chronic obstructive pulmonary disease (COPD)/pulmonary emphysema is driven by the dysregulated airway inflammation and primarily influenced by the interaction between cigarette smoking (CS) and the individual's susceptibility. The inflammation in COPD involves both innate and adaptive immunity. By binding to its specific ligands, chemokine receptor CXCR3 plays an important role in regulating tissue inflammation and damage. In acute animal model challenged with either CS or pathogens, CXCR3 knockout (KO) attenuated lung inflammation and pathology. However, the role of CXCR3 in CS-induced chronic airway inflammation and pulmonary emphysema remains unknown. In this present study, we investigated the effect of CXCR3 in CS-induced pulmonary emphysema in an animal model, and the association between CXCR3 single nucleotide polymorphisms (SNPs) and COPD susceptibility in human subjects. We found that after chronic exposure to side stream CS (SSCS) for 24 weeks, CXCR3 KO mice demonstrated significant airspace enlargement expressed by mean linear intercept (Lm) compared with the wild-type (WT) mice. Consistently, CXCR3 KO mice had significantly higher BAL fluid macrophages and neutrophils, TNFα, and lung homogenate MMP-9 and MMP-12. Through genetic analysis of CXCR3 polymorphisms in a cohort of COPD patients with Han Chinese ethnicity, one CXCR3 SNP, rs2280964, was found to be genetically related to COPD susceptibility. Furthermore, CXCR3 SNP rs2280964 was significantly associated with the levels of serum MMP-9 in COPD patients. Our data from both animal and human studies revealed a novel role of CXCR3 possibly via influencing MMP9 production in the pathogenesis and progression of CS-associated COPD/pulmonary emphysema.

Current knowledge on genetic variants shaping placental transcriptome and their link to gestational and postnatal health

Despite the indispensable role of the placenta in the successful course of pregnancy, regulation of its dynamic transcriptome is still underexplored. The purpose of this literature review was to give an overview and draw attention to the contribution of genetic variation in shaping the human placental gene expression. Studies of placental transcriptome shaped by chromosomal variants are limited and may be confounded by cellular mosaicism and somatic genomic rearrangements. Even in relatively simple cases, such as aneuploidies, the placental transcriptome appears to differ from the assumed systematically increased transcript levels of the involved chromosomes. Single nucleotide variants modulating placental gene expression referred to as expression quantitative trait loci (eQTLs) have been analyzed only in ten candidate gene and three genome-wide association studies (GWAS). The latter identified 417 confident placental eGenes, supported by at least two independent studies. Functional profiling of eGenes highlighted biological pathways important in pregnancy, such as immune response or transmembrane transport activity. A fraction of placental eQTLs (1-3%) co-localize with GWAS loci for adult disorders (metabolic, immunological, neurological), suggesting a co-contributory role of the placenta in the developmental programming of health. Some placental eQTLs have been identified as risk factors for adverse pregnancy outcomes, such as rs4769613 (C > T), located near the FLT1 gene and confidently associated with preeclampsia. More studies are needed to map genetic variants shaping gene expression in different placental cell types across three trimesters in normal and complicated gestations and to clarify to what extent these heritable factors contribute to maternal and offspring disease risks.

CXCR3-Dependent Immune Pathology in Mice following Infection with Toxoplasma gondii during Early Pregnancy

Toxoplasmosis is a worldwide zoonosis caused by the obligate intracellular parasite Toxoplasma gondii The symptoms of congenital toxoplasmosis range from embryonic death and resorption to subclinical infection, but the mechanism of disease onset remains unclear. C-X-C motif chemokine receptor 3 (CXCR3) is highly expressed in Th1-associated immune cells and plays an important role in the trafficking and activation of immune cells. However, the roles of CXCR3 in T. gondii-induced fetal loss and the molecular mechanism of embryo resorption remain poorly understood. In this study, we investigated the role of CXCR3 in fetal wastage caused by T. gondii infection using CXCR3-deficient (CXCR3^-/-) mice. CXCR3^-/- and wild-type pregnant mice were inoculated intraperitoneally with T. gondii tachyzoites on day 3.5 of gestation (Gd3.5). Pregnancy rates decreased as the pregnancy progressed in both infected groups; however, infected CXCR3^-/- mice showed a significant fetal loss at Gd13.5 compared with that at Gd7.5. All embryos of the infected groups showed necrosis, and embryo resorption was significantly increased in infected CXCR3^-/- compared with wild-type mice at Gd13.5. The parasite load of fetoplacental tissues was significantly increased in CXCR3^-/- mice at Gd10.5. Moreover, mRNA expression levels of inducible nitric oxide synthase were significantly increased in fetoplacental tissues from infected wild-type mice compared to infected CXCR3^-/- mice following the infection. These results suggested that CXCR3-dependent immune responses provide anti-Toxoplasma activity and play an essential role in reducing embryo resorption and fetal loss caused by T. gondii infection during early pregnancy.

The transmembrane G protein-coupled CXCR3 receptor-ligand system and maternal foetal allograft rejection

Chronic placental inflammatory lesions lead to poor obstetric outcomes. These lesions often proceed undetected until examination of placental tissues after delivery and are mediated by CXCR3, a seven-transmembrane G protein-coupled receptor, and its chemokine ligands - CXCL9, CXCL10 and CXCL11. CXCR3-chemokine ligand interaction disrupts feto-maternal immune tolerance and activate obnoxious immunological responses similar to transplant rejection and graft-versus-host disease. The resultant chronic inflammatory responses manifest in different parts of the placenta characterised by the presence of incompatible immunocompetent cells from the feto-maternal unit i.e. maternal CD8⁺ T cells in the chorionic membrane or plate (chronic chorioamnionitis); foetal Hofbauer cells and maternal CD8⁺ T cells in the chorionic villous tree (villitis of unknown aetiology); maternal CD8⁺ T and plasma cells in the basal plate (chronic deciduitis); and maternal CD8⁺ T cells, histiocytes and T regulatory cells in the intervillous space (chronic intervillositis). This review critically examines how the CXCR3-chemokine ligand interaction disrupts feto-maternal immune tolerance, initiates a series of chronic placental inflammatory lesions, and consequently activates the pathways to intrauterine growth restriction, stillbirth, spontaneous abortion, preterm prelabour rupture of membranes, preterm labour and birth. The possibility of interrupting these signalling pathways through the use of CXCR3 chemokine inhibitors to prevent adverse reproductive sequelae as well as the potential clinical utility of CXCR3 chemokines as non-invasive predictive clinical biomarkers are also highlighted.

Vaginal host immune-microbiome interactions in a cohort of primarily African-American women who ultimately underwent spontaneous preterm birth or delivered at term

BACKGROUND

Recent studies suggest that alterations in the vaginal microbiome allow for the assessment of the risk for spontaneous preterm birth (PTB), the leading cause of neonatal morbidity and mortality worldwide. However, the associations between the local immune response and the vaginal microbiome are still poorly understood. Herein, we characterize the vaginal host immune-microbiome interactions in women who ultimately underwent PTB and in those who delivered at term.

METHODS

Vaginal fluid samples from 52 pregnant women (of whom 18 underwent PTB and 34 delivered at term) were collected between 10 and 32 weeks of gestation in a case-control study. Concentrations of 33 immune mediators were determined using sensitive and specific immunoassays. The previously published 16S rRNA gene sequence and bacterial phylotype data of these subjects were utilized in this study. Linear mixed effects models were utilized to test associations between vaginal immune mediator concentrations and bacterial phylotype relative abundances.

RESULTS

1) In the overall study population, vaginal concentrations of CXCL10, CCL2, CCL3, SLP1 and VEGF negatively correlated with non-Lactobacillus, Community State Type IV (CST IV) members of the vaginal microbiome; 2) CXCL10, in particular, negatively correlated with 15 bacterial phylotypes, most of which are typical members of CST IV, such as Gardnerella vaginalis, Megasphaera spp., and Atopobium vaginae; 3) Gemella spp., also members of CST IV, negatively correlated with vaginal concentrations of VEGF, CCL2, CCL3, SLPI, and CXCL10; 4) when comparing PTB cases to term controls, five soluble immune mediators (CCL26, CCL22, CCL2, CXCL10, and IL-16), especially CCL26, were negatively correlated with five typical members of CST IV: Sneathia sanguinegens, Parvimonas micra, Veillonellaceae, BVAB2, and Gemella spp.; and 5) Sneathia sanguinegens had stronger negative associations with all five soluble immune mediators (CCL26, CCL22, CCL2, CXCL10, and IL-16) in PTB cases than in term controls.

CONCLUSIONS

The assessment of vaginal host immune-microbiome interactions revealed that specific soluble immune mediators, mainly CXCL10, negatively correlated with typical members of CST IV of the vaginal microbiome. Sneathia sanguinegens, in particular, had stronger negative associations with different immune mediators, including CXCL10 and CCL26, in women who ultimately underwent PTB compared to those who delivered at term. These findings provide insight into the vaginal host immune-microbiome interactions in normal and complicated pregnancies.

CPPED1-targeting microRNA-371a-5p expression in human placenta associates with spontaneous delivery

MicroRNAs (miRNAs) are important regulators of gene expression, and their expression is associated with many physiological conditions. Here, we investigated potential associations between expression levels of miRNAs in human placenta and the onset of spontaneous term birth. Using RNA sequencing, we identified 54 miRNAs differentially expressed during spontaneous term labor compared to elective term births. Expression levels of 23 miRNAs were upregulated, whereas 31 were downregulated at least 1.5-fold. The upregulated miRNA miR-371a-5p putatively targets CPPED1, expression of which decreases during spontaneous birth. We used a luciferase reporter–based assay to test whether a miR-371a-5p mimic affected translation when it bound to the 3′ untranslated region of CPPED1. In this setting, the miR-371a-5p mimic resulted in lower luciferase activity, which suggests that miR-371a-5p regulates levels of CPPED1. In conclusion, inversely correlated levels of miR-371a-5p and CPPED1 suggest a role for both in spontaneous delivery.

The Distinct Roles of CXCR3 Variants and Their Ligands in the Tumor Microenvironment

First thought to orchestrate exclusively leukocyte trafficking, chemokines are now acknowledged for their multiple roles in the regulation of cell proliferation, differentiation, and survival. Dysregulation of their normal functions contributes to various pathologies, including inflammatory diseases and cancer. The two chemokine receptor 3 variants CXCR3-A and CXCR3-B, together with their cognate chemokines (CXCL11, CXCL10, CXCL9, CXCL4, and CXCL4L1), are involved in the control but also in the development of many tumors. CXCR3-A drives the infiltration of leukocytes to the tumor bed to modulate tumor progression (paracrine axis). Conversely, tumor-driven changes in the expression of the CXCR3 variants and their ligands promote cancer progression (autocrine axis). This review summarizes the anti- and pro-tumoral activities of the CXCR3 variants and their associated chemokines with a focus on the understanding of their distinct biological roles in the tumor microenvironment.

Risk of spontaneous preterm birth and fetal growth associates with fetal SLIT2

Spontaneous preterm birth (SPTB) is the leading cause of neonatal death and morbidity worldwide. Both maternal and fetal genetic factors likely contribute to SPTB. We performed a genome-wide association study (GWAS) on a population of Finnish origin that included 247 infants with SPTB (gestational age [GA] < 36 weeks) and 419 term controls (GA 38-41 weeks). The strongest signal came within the gene encoding slit guidance ligand 2 (SLIT2; rs116461311, minor allele frequency 0.05, p = 1.6×10-6). Pathway analysis revealed the top-ranking pathway was axon guidance, which includes SLIT2. In 172 very preterm-born infants (GA <32 weeks), rs116461311 was clearly overrepresented (odds ratio 4.06, p = 1.55×10-7). SLIT2 variants were associated with SPTB in another European population that comprised 260 very preterm infants and 9,630 controls. To gain functional insight, we used immunohistochemistry to visualize SLIT2 and its receptor ROBO1 in placentas from spontaneous preterm and term births. Both SLIT2 and ROBO1 were located in villous and decidual trophoblasts of embryonic origin. Based on qRT-PCR, the mRNA levels of SLIT2 and ROBO1 were higher in the basal plate of SPTB placentas compared to those from term or elective preterm deliveries. In addition, in spontaneous term and preterm births, placental SLIT2 expression was correlated with variations in fetal growth. Knockdown of ROBO1 in trophoblast-derived HTR8/SVneo cells by siRNA indicated that it regulate expression of several pregnancy-specific beta-1-glycoprotein (PSG) genes and genes involved in inflammation. Our results show that the fetal SLIT2 variant and both SLIT2 and ROBO1 expression in placenta and trophoblast cells may be correlated with susceptibility to SPTB. SLIT2-ROBO1 signaling was linked with regulation of genes involved in inflammation, PSG genes, decidualization and fetal growth. We propose that this receptor-ligand couple is a component of the signaling network that promotes SPTB.

Spontaneous premature birth as a target of genomic research

Spontaneous preterm birth is a serious and common pregnancy complication associated with hormonal dysregulation, infection, inflammation, immunity, rupture of fetal membranes, stress, bleeding, and uterine distention. Heredity is 25-40% and mostly involves the maternal genome, with contribution of the fetal genome. Significant discoveries of candidate genes by genome-wide studies and confirmation in independent replicate populations serve as signposts for further research. The main task is to define the candidate genes, their roles, localization, regulation, and the associated pathways that influence the onset of human labor. Genomic research has identified some candidate genes that involve growth, differentiation, endocrine function, immunity, and other defense functions. For example, selenocysteine-specific elongation factor (EEFSEC) influences synthesis of selenoproteins. WNT4 regulates decidualization, while a heat-shock protein family A (HSP70) member 1 like, HSPAIL, influences expression of glucocorticoid receptor and WNT4. Programming of pregnancy duration starts before pregnancy and during placentation. Future goals are to understand the interactive regulation of the pathways in order to define the clocks that influence the risk of prematurity and the duration of pregnancy. Premature birth has a great impact on the duration and the quality of life. Intensification of focused research on causes, prediction and prevention of prematurity is justified.

Prevention of lipopolysaccharide-induced preterm labor by the lack of CX3CL1-CX3CR1 interaction in mice

Preterm labor (PTL) is the most common cause of neonatal death and long-term adverse outcome. The pharmacological agents for PTL prevention are palliative and frequently fail to prevent PTL and improve neonatal outcome. It is essential to fully understand the molecular mechanisms of PTL in order to develop novel therapeutic methods against PTL. Several lines of evidence indicate some chemokines are expressed in gestational tissues during labor or PTL. To reveal the pathophysiological roles of the CX3CL1-CX3CR1 axis in PTL, we performed present study using LPS-induced PTL mice model in CX3CR1-deficient (Cx3cr1^-/-) mice. We indicated that PTL was suppressed in Cx3cr1^-/- mice and immunoneutralization of CX3CL1 in WT mice. From immunohistochemical and the gene expression analyses, the CX3CL1-CX3CR1 axis has detrimental roles in PTL through intrauterine recruitment of macrophages and the enhancement of macrophage-derived inflammatory mediators. Thus, the CX3CL1-CX3CR1 axis may be a good molecular target for preventing PTL.

Spontaneous preterm birth: advances toward the discovery of genetic predisposition

Evidence from family and twin-based studies provide strong support for a significant contribution of maternal and fetal genetics to the timing of parturition and spontaneous preterm birth. However, there has been only modest success in the discovery of genes predisposing to preterm birth, despite increasing sophistication of genetic and genomic technology. In contrast, DNA variants associated with other traits/diseases have been identified. For example, there is overwhelming evidence that suggests that the nature and intensity of an inflammatory response in adults and children are under genetic control. Because inflammation is often invoked as an etiologic factor in spontaneous preterm birth, the question of whether spontaneous preterm birth has a genetic predisposition in the case of pathologic inflammation has been of long-standing interest to investigators. Here, we review various genetic approaches used for the discovery of preterm birth genetic variants in the context of inflammation-associated spontaneous preterm birth. Candidate gene studies have sought genetic variants that regulate inflammation in the mother and fetus; however, the promising findings have often not been replicated. Genome-wide association studies, an approach to the identification of chromosomal loci responsible for complex traits, have also not yielded compelling evidence for DNA variants predisposing to preterm birth. A recent genome-wide association study that included a large number of White women (>40,000) revealed that maternal loci contribute to preterm birth. Although none of these loci harbored genes directly related to innate immunity, the results were replicated. Another approach to identify DNA variants predisposing to preterm birth is whole exome sequencing, which examines the DNA sequence of protein-coding regions of the genome. A recent whole exome sequencing study identified rare mutations in genes encoding for proteins involved in the negative regulation (dampening) of the innate immune response (eg, CARD6, CARD8, NLRP10, NLRP12, NOD2, TLR10) and antimicrobial peptide/proteins (eg, DEFB1, MBL2). These findings support the concept that preterm labor, at least in part, has an inflammatory etiology, which can be induced by pathogens (ie, intraamniotic infection) or "danger signals" (alarmins) released during cellular stress or necrosis (ie, sterile intraamniotic inflammation). These findings support the notion that preterm birth has a polygenic basis that involves rare mutations or damaging variants in multiple genes involved in innate immunity and host defense mechanisms against microbes and their noxious products. An overlap among the whole exome sequencing-identified genes and other inflammatory conditions associated with preterm birth, such as periodontal disease and inflammatory bowel disease, was observed, which suggests a shared genetic substrate for these conditions. We propose that whole exome sequencing, as well as whole genome sequencing, is the most promising approach for the identification of functionally significant genetic variants responsible for spontaneous preterm birth, at least in the context of pathologic inflammation. The identification of genes that contribute to preterm birth by whole exome sequencing, or whole genome sequencing, promises to yield valuable population-specific biomarkers to identify the risk for spontaneous preterm birth and potential strategies to mitigate such a risk.

Chronic inflammatory lesions of the placenta are associated with an up-regulation of amniotic fluid CXCR3: A marker of allograft rejection

OBJECTIVE

The objective of this study is to determine whether the amniotic fluid (AF) concentration of soluble CXCR3 and its ligands CXCL9 and CXCL10 changes in patients whose placentas show evidence of chronic chorioamnionitis or other placental lesions consistent with maternal anti-fetal rejection.

METHODS

This retrospective case-control study included 425 women with (1) preterm delivery (n=92); (2) term in labor (n=68); and (3) term not in labor (n=265). Amniotic fluid CXCR3, CXCL9 and CXCL10 concentrations were determined by ELISA.

RESULTS

(1) Amniotic fluid concentrations of CXCR3 and its ligands CXCL9 and CXCL10 are higher in patients with preterm labor and maternal anti-fetal rejection lesions than in those without these lesions [CXCR3: preterm labor and delivery with maternal anti-fetal rejection placental lesions (median, 17.24 ng/mL; IQR, 6.79-26.68) vs. preterm labor and delivery without these placental lesions (median 8.79 ng/mL; IQR, 4.98-14.7; P=0.028)]; (2) patients with preterm labor and chronic chorioamnionitis had higher AF concentrations of CXCL9 and CXCL10, but not CXCR3, than those without this lesion [CXCR3: preterm labor with chronic chorioamnionitis (median, 17.02 ng/mL; IQR, 5.57-26.68) vs. preterm labor without chronic chorioamnionitis (median, 10.37 ng/mL; IQR 5.01-17.81; P=0.283)]; (3) patients with preterm labor had a significantly higher AF concentration of CXCR3 than those in labor at term regardless of the presence or absence of placental lesions.

CONCLUSION

Our findings support a role for maternal anti-fetal rejection in a subset of patients with preterm labor.

Expression of CPPED1 in human trophoblasts is associated with timing of term birth

Understanding of timing of human parturition is incomplete. Therefore, we carried out proteomic analyses of full-term placentas from uncomplicated pregnancies to identify protein signatures associated with the onset of spontaneous delivery. We found quantitative associations of 10 proteins with spontaneous term birth, evident either in the basal or in the chorionic plates or in both. Additional 18 proteins were associated according to the location within placenta indicating local variations in protein amounts. Calcineurin-like phosphoesterase domain-containing 1 (CPPED1), a phosphatase previously suggested dephosphorylating AKT1/PKB, was one of the identified proteins. qRT-PCR revealed the mRNA level of CPPED1 was higher in elective caesarean deliveries than in spontaneous births, while immunohistochemistry showed CPPED1 in cytotrophoblasts, syncytiotrophoblasts and extravillous trophoblasts. Noteworthy, phosphorylation status of AKT1 did not differ between placentas from elective caesarean and spontaneous deliveries. Additionally, analyses of samples from infants indicated that single-nucleotide polymorphisms rs11643593 and rs8048866 of CPPED1 were associated with duration of term pregnancy. Finally, post-transcriptional silencing of CPPED1 in cultured HTR8/SVneo cells by siRNAs affected gene expression in pathways associated with inflammation and blood vessel development. We postulate that functions regulated by CPPED1 in trophoblasts at choriodecidual interphase have a role in the induction of term labour, but it may be independent of AKT1.

Lymphocytes in Placental Tissues: Immune Regulation and Translational Possibilities for Immunotherapy

Immune modulation at the fetomaternal interface is crucial to ensure that the fetal allograft is not rejected. In the present review, the focus is to describe basic functions of lymphocyte populations and how they may contribute to fetomaternal immune regulation, as well as determining what proportions and effector functions of these cells are reported to be present in placental tissues in humans. Also explored is the possibility that unique cell populations at the fetomaternal interface may be targets for adoptive cell therapy. Increasing the understanding of immune modulation during pregnancy can give valuable insight into other established fields such as allogeneic hematopoietic stem cell transplantation and solid organ transplantation. In these settings, lymphocytes are key components that contribute to inflammation and rejection of either patient or donor tissues following transplantation. In contrast, an allogeneic fetus eludes rejection by the maternal immune system.

Gene expression in term placentas is regulated more by spinal or epidural anesthesia than by late-onset preeclampsia or gestational diabetes mellitus

Pre-eclampsia (PE) and gestational diabetes mellitus (GDM) are common complications of pregnancy, but the mechanisms underlying these disorders remain unclear. The aim was to identify the extent of altered gene expression in term placentas from pregnant women with late-onset PE and GDM compared to controls. RNAseq identified few significantly differentially regulated genes in placental biopsies between PE, GDM, or uncomplicated pregnancy (n = 10 each group). Five genes were altered in placentas from PE including 4 non-coding genes and Angiopoietin 2 (ANGPT2). No genes were significantly regulated by GDM. In contrast, many genes were significantly regulated by fetal, maternal and delivery-specific variables, particularly spinal and epidural anesthesia. We selected ANGPT2 and Chemokine (C-X-C motif) ligand 14 (CXCL14) to test with qPCR in a larger set of placentas (n = 475) and found no differences between the groups. However, regression analysis revealed a stronger association between placental ANGPT2 and CXCL14 mRNA expression and fetal, maternal and delivery-specific variables than diagnostic group. To conclude, the gene expression in term placentas are highly affected by fetal, maternal and delivery specific variables. Few regulated genes were found in late-onset PE and GDM placentas, which may suggest that these conditions could be more affected by maternal factors.