Gene and protein expression in the myometrium in pregnancy and labor

DIA-based quantitative proteomic analysis of porcine endometrium in the peri-implantation phase

The 12th day of gestation is a critical period for embryo loss and the beginning of imminent implantation in sows. Data independent acquisition (DIA) technology is one of the high-throughput, high-resolution and reproducible proteomics technologies for large-scale digital qualitative and quantitative research. The aim of this study was to identify and characterize the protein abundance landscape of Yorkshire pig endometrium on the 12th day of pregnancy (P12) and estrous cycle (C12) using DIA proteomics. A total of 1251 differentially abundant proteins (DAPs) were identified, of which 882 were up-regulated and 369 were down-regulated at P12. Functional enrichment analysis showed that the identified proteins were related to metabolism, biosynthesis and signaling pathways. Three proteins were selected for Western blot (WB) validation and the results were consistent with the DIA data. Further combined with transcriptome data, fibrinogen like 2 (FGL2) and S100 calcium binding protein A8 (S100A8) were verified to be highly abundant in the P12 endometrial epithelium. In summary, there were significantly different abundance of proteome profiles in C12 and P12 endometrium, suggesting that DAPs are associated with changes in endometrial receptivity, which laid the foundation for further research on related regulatory mechanisms. SIGNIFICANCE: The 12th day of gestation is an important point in the peri-implantation period of pigs, when the endometrium presents a receptive state under the stimulation of estrogen. DIA proteomics technology is an emerging protein identification technology in recent years, which can obtain protein information through comprehensive and unbiased scanning. In this study, DIA technology was used to characterize endometrial proteins in pigs during the peri-implantation period. The results showed that higher protein abundance was detected using the DIA technique, and some of these DAPs may be involved in regulating embryo implantation. This study will help to better reveal the related proteins involved in embryo implantation, and lay a foundation for further research on the mechanism of endometrial regulation of embryo implantation. SIGNIFICANCE OF THE STUDY: The 12th day of gestation is an important point in the peri-implantation period of pigs, when the endometrium presents a receptive state under the stimulation of estrogen. DIA proteomics technology is an emerging protein identification technology in recent years, which can obtain protein information through comprehensive and unbiased scanning. In this study, DIA technology was used to characterize endometrial proteins in pigs during the peri-implantation period. The results showed that higher protein abundance was detected using the DIA technique, and some of these DAPs may be involved in regulating embryo implantation. This study will help to better reveal the related proteins involved in embryo implantation, and lay a foundation for further research on the mechanism of endometrial regulation of embryo implantation.

A genome-wide and candidate gene association study of preterm birth in Korean pregnant women

Preterm birth (PTB) refers to delivery before 37 weeks of gestation. Premature neonates exhibit higher neonatal morbidity and mortality rates than term neonates; therefore, it is crucial to predict and prevent PTB. Advancements enable the prediction and prevention of PTB using genetic approaches, especially by investigating its correlation with single nucleotide polymorphisms (SNPs). We aimed to identify impactive and relevant SNPs for the prediction of PTB via whole-genome sequencing analyses of the blood of 31 pregnant women with PTB (n = 13) and term birth (n = 18) who visited the Ewha Womans University Mokdong Hospital from November 1, 2018 to February 29, 2020. A genome-wide association study was performed using PLINK 1.9 software and 256 SNPs were selected and traced through protein-protein interactions. Moreover, a validation study by genotyping was performed on 60 other participants (preterm birth, n = 30; term birth, n = 30) for 25 SNPs related to ion channel binding and receptor complex pathways. Odds ratios were calculated using additive, dominant, and recessive genetic models. The risk of PTB in women with the AG allele of rs2485579 (gene name: RYR2) was significantly 4.82-fold increase, and the risk of PTB in women with the AG allele of rs7903957 (gene name: TBX5) was significantly 0.25-fold reduce. Our results suggest that rs2485579 (in RYR2) can be a genetic marker of PTB, which is considered through the association with abnormal cytoplasmic Ca2+ concentration and dysfunctional uterine contraction due to differences of RYR2 in the sarcoplasmic reticulum.

Transcriptomic and histochemical analysis reveal the complex regulatory networks in equine Chorioallantois during spontaneous term labor

The equine chorioallantois (CA) undergoes complex physical and biochemical changes during labor. However, the molecular mechanisms controlling these changes are still unclear. Therefore, the current study aimed to characterize the transcriptome of equine CA during spontaneous labor and compare it to that of normal preterm CA. Placental samples were collected postpartum from mares with normal term labor (TL group, n = 4) and from preterm not in labor mares (330 days GA; PTNL group, n = 4). Our study identified 4137 differentially expressed genes (DEGs) (1820 upregulated and 2317 downregulated) in CA during TL as compared to PTNL. TL was associated with the upregulation of several pro-inflammatory mediators (MHC-I, MHC-II, NLRP3, CXCL8, and MIF). Also, TL was associated with the upregulation of matrix metalloproteinase (MMP1, MMP2, MMP3, and MMP9) with subsequent extracellular matrix degradation and apoptosis, as reflected by upregulation of several apoptosis-related genes (ATF3, ATF4, FAS, FOS, and BIRC3). In addition, TL was associated with downregulation of 21 transcripts coding for collagens. The upregulation of proteases, along with the downregulation of collagens, is believed to be implicated in separation and rupture of the CA during TL. Additionally, TL was associated with downregulation of transcripts coding for proteins essential for progestin synthesis (SRD5A1 and AKR1C1) and angiogenesis (VEGFA and RTL1), as well as upregulation of prostaglandin synthesis-related genes (PTGS2 and PTGES), which could reflect the physiological switch in placental endocrinology and function during TL. In conclusion, our findings revealed the equine CA gene expression signature in spontaneous labor at term, which improves our understanding of the molecular mechanisms triggering labor.

Leveraging bioengineering to assess cellular functions and communication within human fetal membranes

The fetal membranes enclose the growing fetus and amniotic fluid. Preterm prelabor rupture of fetal membranes is a leading cause of preterm birth. Fetal membranes are composed of many different cell types, both structural and immune. These cells must coordinate functions for tensile strength and membrane integrity to contain the growing fetus and amniotic fluid. They must also balance immune responses to pathogens with maintaining maternal-fetal tolerance. Perturbation of this equilibrium can lead to preterm premature rupture of membranes without labor. In this review, we describe the formation of the fetal membranes to orient the reader, discuss some of the common forms of communication between the cell types of the fetal membranes, and delve into the methods used to tease apart this paracrine signaling within the membranes, including emerging technologies such as organ-on-chip models of membrane immunobiology.

Time Course Analysis of Transcriptome in Human Myometrium Depending on Labor Duration and Correlating With Postpartum Blood Loss

The maintenance of coordinated powerful episodic contractions of the uterus is the crucial factor for normal labor. The uterine contractility is gradually enhanced with the progression of labor, which is related to the gene expression of the myometrium. Competing endogenous RNA (ceRNA) can also regulate the gene expression. To better understand the role of ceRNA network in labor, transcriptome sequencing was performed on the myometrium of 17 parturients at different labor durations (0–24 h). From this, expression levels of mRNA, long non-coding RNA (lncRNA), circular RNA (circRNA), and microRNA (miRNA) were correlated with labor duration. Then, targeting relationships between mRNAs, lncRNAs, circRNAs, and miRNAs were predicted, and the ceRNA regulatory network was established. The mRNA expression patterns associated with cervical dilation and postpartum bleeding were further investigated. This analysis identified 932 RNAs positively correlated with labor duration (859 mRNAs, 28 lncRNAs, and 45 circRNAs) and 153 RNAs negatively correlated with labor duration (122 mRNAs, 28 lncRNAs, and 3 miRNAs). These mRNAs were involved in protein metabolism, transport, and cytoskeleton functions. According to the targeting relationship among these ceRNAs and mRNAs, a ceRNA network consisting of 3 miRNAs, 72 mRNAs, 2 circRNAs, and 1 lncRNA was established. In addition, two mRNA expression patterns were established using time-series analysis of mRNA expression in different phases of cervical dilation. A ceRNA network analysis for blood loss was performed; postpartum bleeding was closely related to inflammatory response, angiogenesis, and hemostasis. This study identified human myometrial transcriptome and established the ceRNA regulatory network depending on labor duration and highlighted the dynamic changes that occur at ceRNAs during parturition, which need to be considered more in the future to better understand how changes in gene expression are relevant to functional changes in human myometrium at labor.

Expression and functional maintenance of volume-regulated anion channels in myometrial smooth muscles of pregnant mice

Pregnancy causes changes in the uterus, such as increased cell volume and altered water content. However, the mechanisms that protect the structure and maintain the function of uterine smooth muscle cells against these changes during pregnancy have not been clarified. This study focused on the volume-regulated anion channel (VRAC), which opens with cell swelling under low osmotic pressure and releases Cl- ions and various organic osmolytes to resist cell swelling and regulates a wide range of biological processes such as cell death. In this study, myometrial smooth muscle (MSM) tissues and cells (MSMCs) were collected from non-pregnant and pregnant mice. Using western blotting and immunocytochemistry, leucine-rich repeat containing protein 8A (LRRC8A), an essential membrane protein that constitutes part of the VRAC, was determined to be diffused throughout MSMCs including in the cell membrane. Patch-clamp experiments were performed to investigate the electrophysiology of swelling-induced Cl- currents (ICl, swell) mediated by the VRAC. No significant changes between non-pregnancy and pregnancy groups were observed in either the expression density of LRRC8A or the current density of ICl, swell, however the presence of LRRC8A on the cell membrane was significantly increased in the third trimester of pregnancy compared to the non-pregnancy. This study suggests that the VRAC may play a role, such as maintaining cellular homeostasis in the pregnant MSM.

Molecular Characterisation of Uterine Endometrial Proteins during Early Stages of Pregnancy in Pigs by MALDI TOF/TOF

The molecular mechanism underlying embryonic implantation is vital to understand the correct communications between endometrium and developing conceptus during early stages of pregnancy. This study’s objective was to determine molecular changes in the uterine endometrial proteome during the preimplantation and peri-implantation between 9 days (9D), 12 days (12D), and 16 days (16D) of pregnant Polish Large White (PLW) gilts. 2DE-MALDI-TOF/TOF and ClueGO^TM approaches were employed to analyse the biological networks and molecular changes in porcine endometrial proteome during maternal recognition of pregnancy. A total of sixteen differentially expressed proteins (DEPs) were identified using 2-DE gels and MALDI-TOF/TOF mass spectrometry. Comparison between 9D and 12D of pregnancy identified APOA1, CAPZB, LDHB, CCT5, ANXA4, CFB, TTR upregulated DEPs, and ANXA5, SMS downregulated DEPs. Comparison between 9D and 16D of pregnancy identified HP, APOA1, ACTB, CCT5, ANXA4, CFB upregulated DEPs and ANXA5, SMS, LDHB, ACTR3, HP, ENO3, OAT downregulated DEPs. However, a comparison between 12D and 16D of pregnancy identified HP, ACTB upregulated DEPs, and CRYM, ANXA4, ANXA5, CAPZB, LDHB, ACTR3, CCT5, ENO3, OAT, TTR down-regulated DEPs. Outcomes of this study revealed key proteins and their interactions with metabolic pathways involved in the recognition and establishment of early pregnancy in PLW gilts.

NF-κB and Its Regulators During Pregnancy

The transcriptional factor NF-κB is a nuclear factor involved in both physiological and pathological processes. This factor can control the transcription of more than 400 genes, including cytokines, chemokines, and their modulators, immune and non-immune receptors, proteins involved in antigen presentation and cell adhesion, acute phase and stress response proteins, regulators of apoptosis, growth factors, other transcription factors and their regulators, as well as different enzymes; all these molecules control several biological processes. NF-κB is a tightly regulated molecule that has also been related to apoptosis, cell proliferation, inflammation, and the control of innate and adaptive immune responses during onset of labor, in which it has a crucial role; thus, early activation of this factor may have an adverse effect, by inducing premature termination of pregnancy, with bad outcomes for the mother and the fetus, including product loss. Reviews compiling the different activities of NF-κB have been reported. However, an update regarding NF-κB regulation during pregnancy is lacking. In this work, we aimed to describe the state of the art around NF-κB activity, its regulatory role in pregnancy, and the effect of its dysregulation due to invasion by pathogens like Trichomonas vaginalis and Toxoplasma gondii as examples.

Genome-wide scan reveals genomic regions and candidate genes underlying direct and maternal effects of preweaning calf mortality in Nellore cattle

We conducted analysis to estimate genetic parameters and to identify genomic regions and candidate genes affecting direct and maternal effects of preweaning calf mortality (PWM) in Nellore cattle. Phenotypic records of 67,196 animals, and 8443 genotypes for 410,936 SNPs were used. Analysis were performed through the weighted single-step GBLUP approach and considering a threshold animal model via Bayesian Inference. Direct and maternal heritability estimates were of 0.2143 ± 0.0348 and 0.0137 ± 0.0066, respectively. The top 10 genomic regions accounted for 13.61 and 14.23% of the direct and maternal additive genetic variances and harbored a total of 63 and 91 positional candidate genes, respectively. Two overlapping regions on BTA2 were identified for both direct and maternal effects. Candidate genes are involved in biological mechanisms i.e. embryogenesis, immune response, feto-maternal communication, circadian rhythm, hormone alterations, myometrium adaptation, and milk secretion, which are critical for the successful calf growth and survival during preweaning period.

Relationship between cervical elastography and spontaneous onset of labor

Cervical elastography might be an objective method for evaluating cervical ripening during pregnancy, but its usefulness has not been fully investigated. We examined the significance of cervical elastography in the last trimester of pregnancy. Cervical elastography was performed at weekly checkups after 36 weeks of gestation in 238 cases delivered at our hospital from 2017 to 2018. The correlation with the onset time of natural labor, which is an index for judging maternal delivery preparation status, was examined. A total of 765 examinations were conducted, and cervical stiffness determined by cervical elastography was positively correlated with the Bishop score (r = 0.46, p < 0.0001). When examined separately for each week, only the examinations performed at 39 weeks were associated with the onset of spontaneous labor up to 7 days later (p = 0.0004). Furthermore, when stratified and analyzed by the Bishop score at 39 weeks of gestation, cervical elastography was associated with the occurrence of spontaneous labor pain for up to seven days in the groups with Bishop scores of 3–5 and 6–8 (p = 0.0007 and p = 0.03, respectively). In conclusion, cervical elastography at 39 weeks of pregnancy is useful for judging the delivery time.

Decrease in SHP-1 enhances myometrium remodeling via FAK activation leading to labor

Preterm birth is one of the most common complications during human pregnancy and is associated with a dramatic switch within the uterus from quiescence to contractility. However, the mechanisms underlying uterine remodeling are largely unknown. Protein kinases and phosphatases play critical roles in regulating the phosphorylation of proteins involved in the smooth muscle cell functions. In the present study, we found that Src-homology phosphatase type-1 (SHP-1, PTPN6) was significantly decreased in human myometrium in labor compared with that not in labor. Timed-pregnant mice injected intraperitoneally with the specific SHP-1 inhibitor protein tyrosine phosphatase inhibitor I (PTPI-1) manifested significantly preterm labor, with enriched plasmalemmal dense plaques between myometrial cells and increased phosphorylation at Tyr397 and Tyr576/577 sites of focal adhesion kinase (FAK) in myometrial cells, which remained to the time of labor, whereas the phosphorylation levels of ERK1/2 and phosphatidylinositol 3 kinase (PI3K) showed a rapid increase upon PTPI-1 injection but fell back to normal at the time of labor. The Tyr576/577 in FAK played an important role in the interaction between FAK and SHP-1. Knockdown of SHP-1 dramatically increased the spontaneous contraction of human uterine smooth muscle cells (HUSMCs), which was reversed by coinfection of a FAK-knockdown lentivirus. PGF_2α downregulated SHP-1 via PLCβ-PKC-NF-κB or PI3K-NF-κB pathways, suggesting the regenerative downregulation of SHP-1 enhances the uterine remodeling and plasticity by activating FAK and subsequent focal adhesion pathway, which eventually facilitates myometrium contraction and leads to labor. The study sheds new light on understanding of mechanisms that underlie the initiation of labor, and interventions for modulation of SHP-1 may provide a potential strategy for preventing preterm birth.

Variable Responsiveness to Agonists for TLR2 and TLR7 in Myometrial Cells from Different Sources: Correlation with Receptor Expression

The myometrium plays a vital role in maintenance of pregnancy. Disruption of myometrial sensitivity to pro-contractile stimuli might lead to preterm labor. Inflammation and/or infection are common precursors to preterm birth, in part by initiating pro-contractile stimuli through toll-like receptor (TLRs) activation. In this study, we investigated the responses specific to inflammatory stimuli for both human primary myometrial cells (HPMCs) and PHM1-41 cells, a human immortalized myometrial cell line. Both these types of cells are commonly used to study labor and pregnancy. Both cell lines were treated with lipopolysaccharide (LPS), peptidoglycan (PGN), or imiquimod (IQ) (ligands for TLRs 2, 4, and 7, respectively). We demonstrate that inflammatory cytokines increase significantly with LPS treatment; however, no change occurs with PGN and IQ, suggesting lack of TLR2- and TLR7-specific signaling in both HPMCs and in the PHM1-41 cell line. Absence of TLR2- and TLR7-specific protein bands on western blots confirmed the lack of these receptors in both HPMCs maintained in long-term culture and PHM1-41 cells. However, TLR2 expression was present in freshly collected matched human myometrial tissue (i.e., the tissues used to create the HPMC cultures), showing loss of TLR2 receptors by HPMCs during the cell culturing process. TLR7 protein expression was lacking both in myometrial tissue and in cultured cells. These results demonstrate the limited applicability and reliability of cellular models to investigate the role of the myometrium during pregnancy and labor.

Transcriptomic analysis reveals the key regulators and molecular mechanisms underlying myometrial activation during equine placentitis†

The key event in placentitis-induced preterm labor is myometrial activation with the subsequent initiation of labor. However, the molecular mechanisms underlying myometrial activation are not fully understood in the mares. Therefore, the equine myometrial transcriptome was characterized during placentitis (290.0 ± 1.52 days of GA, n = 5) and the prepartum period (330 days of GA, n = 3) in comparison to normal pregnant mares (289.8 ± 2.18 days of GA, n = 4). Transcriptome analysis identified 596 and 290 DEGs in the myometrium during placentitis and the prepartum period, respectively, with 138 DEGs in common. The placentitis DEGs included eight genes (MMP1, MMP8, S100A9, S100A8, PI3, APOBEC3Z1B, RETN, and CXCL2) that are exclusively expressed in the inflamed myometrium. Pathway analysis elucidated that inflammatory signaling, Toll-like receptor signaling, and apoptosis pathways dominate myometrial activation during placentitis. The prepartum myometrium was associated with overexpression of inflammatory signaling, oxidative stress, and 5-hydroxytryptamine degradation. Gene ontology enrichment analysis identified several chemoattractant factors in the myometrium during placentitis and prepartum period, including CCL2, CXCL1, CXCL3, and CXCL6 in common. Upstream regulator analysis revealed 19 potential upstream regulators in placentitis dataset including transcription regulators (E2F1, FOXM1, HIF1A, JUNB, NFKB1A, and STAT1), transmembrane receptors (FAS, ICAM1, SELP, TLR2, and TYROBP), growth factors (HGF and TGFB3), enzymes (PTGS2 and PRKCP), and others (S100A8, S100A9, CD44, and C5AR1). Additionally, three upstream regulators (STAT3, EGR1, and F2R) were identified in the prepartum dataset. These findings revealed the key regulators and pathways underlying myometrial activation during placentitis, which aid in understanding the disease and facilitate the development of efficacious therapies.

Comparison of the myometrial transcriptome from singleton and twin pregnancies by RNA-Seq

Preterm birth is recognized as the primary cause of infant mortality worldwide. Twin pregnancies are significantly more at risk of preterm birth than singleton pregnancies. A greater understanding of why this is and better modes of treatment and prevention are needed. Key to this is determining the differing pathophysiological mechanisms of preterm birth in twins, including the role of the myometrium and premature uterine contraction. We performed RNA sequencing (RNA-Seq) of human myometrium from singleton and twin pregnancies at term (> 37+0 weeks) and preterm (< 37+0 weeks), collected during pre-labour Caesarean Section. RNA-Seq libraries were prepared from polyA-selected RNA and sequenced on the Illumina HiSeq 4000 platform. Differentially expressed genes (DEGs), GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway enrichment were conducted using R software. Significance was determined with a false discovery rate-adjusted P value of <0.05. Only 3 DEGs were identified between gestational age-matched singleton and twin myometrium and only 1 DEG identified between singleton term and twin preterm tissues. Comparison of singleton preterm myometrium with twin term myometrium however, revealed 75 down-regulated and 24 up-regulated genes in twin myometrium. This included genes associated with inflammation and immune response, T cell maturation and differentiation and steroid biosynthesis. GO and KEGG enrichment analyses for biologically relevant processes and functions also revealed several terms related to inflammation and immune response, as well as cytokine-cytokine receptor interaction and chemokine receptor signalling. Data indicate that little or no differences exist in the transcriptome of singleton and twin myometrium when matched for gestational age. The significant up- and down-regulation of genes identified between preterm singleton and twin myometrium at term may point to transcriptome changes associated with the chronic levels of uterine stretch in twin pregnancy or genes associated with the myometrium transitioning to labour onset.

Integrated microRNA and mRNA network analysis of the human myometrial transcriptome in the transition from quiescence to labor

We conducted integrated transcriptomics network analyses of miRNA and mRNA interactions in human myometrium to identify novel molecular candidates potentially involved in human parturition. Myometrial biopsies were collected from women undergoing primary Cesarean deliveries in well-characterized clinical scenarios: (1) spontaneous term labor (TL, n = 5); (2) term nonlabor (TNL, n = 5); (3) spontaneous preterm birth (PTB) with histologic chorioamnionitis (PTB-HCA, n = 5); and (4) indicated PTB nonlabor (PTB-NL, n = 5). RNAs were profiled using RNA sequencing, and miRNA-target interaction networks were mined for key discriminatory subnetworks. Forty miRNAs differed between TL and TNL myometrium, while seven miRNAs differed between PTB-HCA vs. PTB-NL specimens; six of these were cross-validated using quantitative PCR. Based on the combined sequencing data, unsupervised clustering revealed two nonoverlapping cohorts that differed primarily by absence or presence of uterine quiescence, rather than gestational age or original clinical cohort. The intersection of differentially expressed miRNAs and their targets predicted 22 subnetworks with enriched representation of miR-146b-5p, miR-223-3p, and miR-150-5p among miRNAs, and of myocyte enhancer factor-2C (MEF2C) among mRNAs. Of four known MEF2 transcription factors, decreased MEF2A and MEF2C expression in women with uterine nonquiescence was observed in the sequencing data, and validated in a second cohort by quantitative PCR. Immunohistochemistry localized MEF2A and MEF2C to myometrial smooth muscle cells and confirmed decreased abundance with labor. Collectively, these results suggest altered MEF2 expression may represent a previously unrecognized process through which miRNAs contribute to the phenotypic switch from quiescence to labor in human myometrium.

Myometrial Transcriptional Signatures of Human Parturition

The process of parturition involves the transformation of the quiescent myometrium (uterine smooth muscle) to the highly contractile laboring state. This is thought to be driven by changes in gene expression in myometrial cells. Despite the existence of multiple myometrial gene expression studies, the transcriptional programs that initiate labor are not known. Here, we integrated three transcriptome datasets, one novel (NCBI Gene Expression Ominibus: GSE80172) and two existing, to characterize the gene expression changes in myometrium associated with the onset of labor at term. Computational analyses including classification, singular value decomposition, pathway enrichment, and network inference were applied to individual and combined datasets. Outcomes across studies were integrated with multiple protein and pathway databases to build a myometrial parturition signaling network. A high-confidence (significant across all studies) set of 126 labor genes were identified and machine learning models exhibited high reproducibility between studies. Labor signatures included both known (interleukins, cytokines) and unknown (apoptosis, MYC, cell proliferation/differentiation) pathways while cyclic AMP signaling and muscle relaxation were associated with non-labor. These signatures accurately classified and characterized the stages of labor. The data-derived parturition signaling networks provide new genes/signaling interactions to understand phenotype-specific processes and aid in future studies of parturition.

RNA-sequencing analysis of umbilical cord plasma microRNAs from healthy newborns

MicroRNAs are a class of small non-coding RNA that regulate gene expression at a post-transcriptional level. MicroRNAs have been identified in various body fluids under normal conditions and their stability as well as their dysregulation in disease has led to ongoing interest in their diagnostic and prognostic potential. Circulating microRNAs may be valuable predictors of early-life complications such as birth asphyxia or neonatal seizures but there are relatively few data on microRNA content in plasma from healthy babies. Here we performed small RNA-sequencing analysis of plasma processed from umbilical cord blood in a set of healthy newborns. MicroRNA levels in umbilical cord plasma of four male and four female healthy babies, from two different centres were profiled. A total of 1,004 individual microRNAs were identified, which ranged from 426 to 659 per sample, of which 269 microRNAs were common to all eight samples. Many of these microRNAs are highly expressed and consistent with previous studies using other high throughput platforms. While overall microRNA expression did not differ between male and female cord blood plasma, we did detect differentially edited microRNAs in female plasma compared to male. Of note, and consistent with other studies of this type, adenylation and uridylation were the two most prominent forms of editing. Six microRNAs, miR-128-3p, miR-29a-3p, miR-9-5p, miR-218-5p, 204-5p and miR-132-3p were consistently both uridylated and adenylated in female cord blood plasma. These results provide a benchmark for microRNA profiling and biomarker discovery using umbilical cord plasma and can be used as comparative data for future biomarker profiles from complicated births or those with early-life developmental disorders.

Changes in expression of P2X7 receptors in rat myometrium at different gestational stages and the mechanism of ATP-induced uterine contraction

AIMS

Given the importance of ATP in the control of uterine activity for successful labor and involution, this study was performed to measure the level of P2X7 receptors (P2X7Rs) in rat myometrium at different gestational stages and to investigate the mechanisms of ATP-induced uterine contraction.

MATERIALS AND METHODS

Myometrial tissues were obtained from rats at different gestational stages and the level of P2X7Rs was measured by ELISA. In other experiments, the effect of 1 mM ATP was tested on spontaneous contraction and the underlying mechanisms were investigated.

KEY FINDINGS

P2X7Rs were expressed in nonpregnant uterine tissues, progressively increased throughout pregnancy, and markedly peaked during postpartum involution. ATP significantly increased the force of spontaneous contraction in all uterine strips from different gestational stages with marked increase during labor and postpartum. ATP could not maintain the force when external Ca²⁺ was removed. In addition, ATP was able to cause tonic transient contraction in the absence of external Ca²⁺.

SIGNIFICANCE

P2X7Rs are functionally regulated and contributed to ATP-induced uterine contraction. The sensitivity of the myometrium to ATP increases as pregnancy progresses and it involves Ca²⁺ influx and Ca²⁺ release pathways. The clear effects of ATP on contractility suggest its physiological requirement for successful labor and postpartum involution.

Genome-wide association studies and genomic prediction of breeding values for calving performance and body conformation traits in Holstein cattle

Background

Our aim was to identify genomic regions via genome-wide association studies (GWAS) to improve the predictability of genetic merit in Holsteins for 10 calving and 28 body conformation traits. Animals were genotyped using the Illumina Bovine 50 K BeadChip and imputed to the Illumina BovineHD BeadChip (HD). GWAS were performed on 601,717 real and imputed single nucleotide polymorphism (SNP) genotypes using a single-SNP mixed linear model on 4841 Holstein bulls with breeding value predictions and followed by gene identification and in silico functional analyses. The association results were further validated using five scenarios with different numbers of SNPs.

Results

Seven hundred and eighty-two SNPs were significantly associated with calving performance at a genome-wise false discovery rate (FDR) of 5%. Most of these significant SNPs were on chromosomes 18 (71.9%), 17 (7.4%), 5 (6.8%) and 7 (2.4%) and mapped to 675 genes, among which 142 included at least one significant SNP and 532 were nearby one (100 kbp). For body conformation traits, 607 SNPs were significant at a genome-wise FDR of 5% and most of them were located on chromosomes 5 (30%), 18 (27%), 20 (13%), 6 (6%), 7 (5%), 14 (5%) and 13 (3%). SNP enrichment functional analyses for calving traits at a FDR of 1% suggested potential biological processes including musculoskeletal movement, meiotic cell cycle, oocyte maturation and skeletal muscle contraction. Furthermore, pathway analyses suggested potential pathways associated with calving performance traits including tight junction, oxytocin signaling, and MAPK signaling (P < 0.10). The prediction ability of the 1206 significant SNPs was between 78 and 83% of the prediction ability of the BovineSNP50 SNPs for calving performance traits and between 35 and 79% for body conformation traits.

Conclusions

Various SNPs that are significantly associated with calving performance are located within or nearby genes with potential roles in tight junction, oxytocin signaling, and MAPK signaling. Combining the significant SNPs or SNPs within or nearby gene(s) from the HD panel with the BovineSNP50 panel yielded a marginal increase in the accuracy of prediction of genomic estimated breeding values for all traits compared to the use of the BovineSNP50 panel alone.

Electronic supplementary material

The online version of this article (10.1186/s12711-017-0356-8) contains supplementary material, which is available to authorized users.

Is myometrial inflammation a cause or a consequence of term human labour?

Myometrial inflammation is thought to have a pivotal role in the onset of term and some forms of preterm labour. This is based on the comparison of samples taken from women undergoing term elective CS prior to the onset of labour with those taken from women in established labour. Consequently, it is not clear whether myometrial inflammation is a cause or a consequence of labour. Our objective is to test the hypothesis that myometrial inflammation is a consequence of the onset of labour. To test this hypothesis, we have obtained myometrial samples from women at various stages of pregnancy and spontaneous labour and studied the activation of the AP-1 (c-Jun) and NFκB (p65) systems, cytokine mRNA expression and protein levels and inflammatory cell infiltration and activation. We found that the activation of p65 declined from preterm to term not in labour samples and thereafter increased in early and established labour. Cytokine mRNA expression and protein levels increased in established labour only. Using flow cytometry of myometrial tissue, we found that the number of neutrophils did increase with the onset of labour, but on tissue section, these were seen to be intravascular and not infiltrating into the myometrium. These data suggest that myometrial inflammation is a consequence rather than a cause of term labour.

Insights from physiology into myometrial function and dysfunction

NEW FINDINGS

What is the topic of this review? I focus on clinical aspects of uterine physiology, specifically, myometrial contractility. I bring together and contrast findings using physiological approaches and those using newer techniques, 'omics'. What advances does it highlight? Physiological studies have recently shed light on the myometrium in twin pregnancies, but there have been no 'omic' approaches. In contrast, studies of preterm delivery using newer approaches are generating new research avenues, whereas traditional approaches have not flourished. Finally, I describe significant advances in understanding of 'slow-to-progress' labours, achieved using physiological and clinical approaches. Advances in molecular, genetic and 'omic' technologies are fuelling the thirst for better understanding of the uterus and application of this information to problems in pregnancy and labour. Progress has, however, been limited while we still have an incomplete understanding of some of the basic physiology of uterine smooth muscle (myometrium). In this review and opinion piece, I explore some of the fascinating findings from selected recent studies and see how these may provide new avenues for physiological and clinical research. It is also the case, however, that there is still limited mechanistic understanding about physiological and pathophysiological processes in the myometrium. This lack of understanding limits the usefulness of some findings from genomic and allied studies. By focusing on some key recent findings and relating these to two important clinical problems in childbirth that involve myometrial activity, namely preterm delivery and difficult labours, the interplay between our physiological knowledge and the information provided by newer technologies is explored. My opinion is that physiology has provided much more new mechanistic insight into difficult births and that the newer technologies may lead to breakthroughs in preterm birth research, but that this has not yet happened.

Hypoxia-induced force increase (HIFI) is a novel mechanism underlying the strengthening of labor contractions, produced by hypoxic stresses

For successful birth, contractions need to become progressively stronger. The underlying mechanisms are unknown, however. We have found that a novel mechanism, hypoxia-induced force increase (HIFI), is switched on selectively, at term, and is essential to strengthening contractions. HIFI is initiated as contractions cyclically reduce blood flow and produce repeated hypoxic stresses, with associated metabolic and transcriptomic changes. The increases in contractility are a long-lasting, oxytocin-independent, intrinsic mechanism present only in the full-term pregnant uterus. HIFI is inhibited by adenosine receptor antagonism and blockade of cyclooxygenase-2 signaling, and partially reproduced by brief episodes of acidic (but not alkalotic) pH. HIFI explains how labor can progress despite paradoxical metabolic challenge, and provides a new mechanistic target for the 1 in 10 women suffering dysfunctional labor because of poor contractions.

Blood SC5b-9 complement levels increase at parturition during term and preterm labor

We explored the hypothesis that complement, an innate and adaptive immune effector, is active in the plasma of parturient women and is deposited on fetal membranes collected after delivery. A cross-sectional study was designed to evaluate complement activity at parturition. Pregnant women (n = 97) between 15 and 41 years of age were enrolled in a hospital protocol during the perinatal period to assess both SC5b-9 complement activity in blood and complement deposition on fetal membranes during parturition. Soluble SC5b-9 complement activity in plasma fractions was measured using a standard enzyme-linked immunosorbent assay (ELISA) that included specific anti-complement antibodies. Complement deposition on membranes was analyzed using immuno-dot blots and immunohistochemistry. Soluble SC5b-9 complement complex levels were increased in the plasma of women during term labor (TL; median 3361; range 1726-5670 ng/mL), preterm labor (PL; median 2958; range 1552-7092 ng/mL), and preterm premature rupture of membranes (PPROM; median 2272; range 167-6540 ng/mL) compared with pregnant women who were not in labor (P; median 1384; range 174-4570 ng/mL; P < 0.001, Kruskal-Wallis test). Active complement, as assessed by the C9 neo-antigen in C5b-9 complexes, was deposited on fetal membranes, with no difference between term and preterm delivery. The deposition of active complement on fetal membranes was confirmed by immunohistochemistry. Women who underwent non-labor-indicated Cesarean sections did not exhibit complement deposition. Soluble SC5b-9 complement complex levels increased in the plasma of women during parturition, and complement C5b-9 complexes were deposited on fetal membranes.

Expression of tumor necrosis factor-alpha and vascular endothelial growth factor in different zones of fetal membranes: a possible relation to onset of labor

This study aimed to explore whether the altered expression of tumor necrosis factor-alpha (TNF-α), vascular endothelial growth factor (VEGF) and apoptotic changes in mid zone (MZ) and rupture zone (RZ) of fetal membranes (FM) are regulatory mechanisms associated with labor at term. Fifteen FM specimens were collected after vaginal deliveries and 13 specimens after elective caesarian section. Histological and immunohistochemical analysis were employed. Area percent of TNF-α and VEGF immunostaining and apoptotic index (AI) were evaluated using image analysis. The statistical data revealed significantly higher area % for TNF-α, VEGF immunoexpression and AI in labor compared to non-labor specimens (p < 0.0001). There was a significantly higher percentage of TNF-α immunoexpressed area in MZ compared with RZ in both groups (p < 0.0001). VEGF expression in RZ of both groups proved nearly double or triple the area % of expression relative to MZ with highly significant difference (p < 0.0001). quantitative analysis revealed near two fold increase in the AI in RZ (13.42% ± 1.2 in labor; 11.20% ± 0.96 in non-labor groups) when compared to MZ (7.20% ± 0.6 in labor; 5.08% ± 0.76 in non-labor groups) with highly significant zonal difference (p < 0.0001). Correlation analysis revealed significant correlation between apoptotic indices and area % of TNF-α (r = 0.575, p = 0.002 in non-labor; r = 0.652, p < 0.0001 in labor) and VEGF (r = 0.795, p < 0.0001 in non-labor; r = 0.668, p < 0.0001 in labor). In conclusion, Apoptosis may be regulated by TNF-α and VEGF expression in FM at labor. MZ is a step back from RZ and could participate actively in rupture of the FM during labor. TNF-α and VEGF increase with onset of labor and differentially expressed in the RZ and the MZ. These findings call for further study with tissue cultures or animal models.

Effect of micronutrient supplementation on the immune function of crossbred dairy cows under semi-arid tropical environment

This study assessed the effect of micronutrient supplementation around peripartum period on immune function, reproductive performance, milk yield and milk quality of crossbred cows. Thirty pregnant crossbred cows in their late gestation were selected and randomly divided into five groups for study. Six cows in each group were supplemented with vitamin E (VE) (2000 IU/cow/day), vitamin A (VA) (100,000 IU/cow/day), copper (Cu) (20 ppm/cow/day), zinc (Zn) (80 ppm/cow/day) individually from 45 days pre-calving to 45 days post-calving and one group without any supplementation served as control. Immune function was studied by in vitro phagocytic activity (PA) of blood neutrophils, lymphocyte proliferation response (LPR) and plasma interleukin-8 (IL-8) concentration. Supplementation of VA significantly (P < 0.05) increased the in vitro PA of blood neutrophils and decreased milk somatic cell counts (SCC). Zn supplementation significantly (P < 0.05) increased the T lymphocyte proliferation response, whereas B lymphocyte LPR was significantly (P < 0.05) increased with both VA and Zn supplementation as compared to the control cows. Plasma IL-8 concentration was significantly (P < 0.05) higher in all supplemented cows. Supplementation of VE, VA and Zn significantly (P < 0.05) reduces days open, whereas VA significantly (P < 0.05) reduced the service per conception. In this study, it is concluded that VE, VA and Zn supplementation around peripartum period can boost the immunity and improve the reproductive performance of crossbred cows in a semi-arid tropical environment.

The physiological roles of placental corticotropin releasing hormone in pregnancy and childbirth

In response to stress, the hypothalamus releases cortiticotropin releasing hormone (CRH) that travels to the anterior pituitary, where it stimulates the release of adrenocorticotropic hormone (ACTH). ACTH travels to the adrenal cortex, where it stimulates the release of cortisol and other steroids that liberate energy stores to cope with the stress. During pregnancy, the placenta synthesises CRH and releases it into the bloodstream at increasing levels to reach concentrations 1,000 to 10, 000 times of that found in the non-pregnant individual. Urocortins, which are CRH analogues are also secreted by the placenta. Desensitisation of the maternal pituitary to CRH and resetting after birth may be a factor in post-partum depression. Recently, CRH has been found to modulate glucose transporter (GLUT) proteins in placental tissue, and therefore there may be a link between CRH levels and foetal growth. Evidence suggests CRH is involved in the timing of birth by modulating signalling systems that control the contractile properties of the myometrium. In the placenta, cortisol stimulates CRH synthesis via activation of nuclear factor kappa B (NF-κB), a component in a cellular messenger system that may also be triggered by stressors such as hypoxia and infection, indicating that intrauterine stress could bring forward childbirth and cause low birth weight infants. Such infants could suffer health issues into their adult life as a result of foetal programming. Future treatment of these problems with CRH antagonists is an exciting possibility.

Vitamin D elicits anti-inflammatory response, inhibits contractile-associated proteins, and modulates Toll-like receptors in human myometrial cells

Infection during pregnancy triggers inflammation, which can increase myometrial contractions and the risk of premature labor and delivery. In this study, we assessed the effects of vitamin D, an anti-inflammatory ligand on cytokines, chemokines, toll-like receptors, and contractile-associated proteins on immortalized human myometrial smooth muscle (UtSM) cells stimulated with lipopolysaccharide (LPS), a bacterial endotoxin, or interleukin (IL)-1β and measured Toll-like receptor (TLR)-10 expression in pregnant myometrial tissues. A superarray analysis revealed downregulation of the chemokines monocyte chemoattractant protein (MCP)-1, Chemokine (C-X-C motif) ligand (CXCL)-10, CXCL-11, and chemokine (C-X3-C motif) ligand (CX3CL)-1; the proinflammatory cytokines IL-13 and tumor necrosis factor (TNF)-α; the TLR-4 and -5 and triggering receptor expressed on myeloid cells (TREM)-2 and upregulation of the anti-inflammatory cytokine IL-10, as well as Toll interacting protein (TOLLIP) and TREM-1 in vitamin D-treated UtSM cells. In the presence of LPS, vitamin D caused dose-dependent decreases in the messenger RNA expression of MCP-1, IL-1β, IL-13, TNF-α, TLR-4, and TLR-5, the contractile-associated proteins connexin 43, the oxytocin receptor, and the prostaglandin receptor but caused increases in IL-10 and TLR-10 in UtSM cells. The TLR-10 expression was higher in human myometrial tissue obtained from women at term not in labor compared to labor. Vitamin D also attenuated IL-1β-induced MCP-1, IL-6, connexin 43, cyclooxygenase (COX)-2, and prostaglandin receptor expression. Western analysis showed that vitamin D decreased MCP-1, TLR-4, and connexin 43 in the presence of LPS and decreased connexin 43 in the presence of IL-1β. Our results suggest that vitamin D can potentially decrease infection-induced increases in cytokines and contractile-associated proteins in the myometrium.

CRH acts on CRH-R1 and -R2 to differentially modulate the expression of large-conductance calcium-activated potassium channels in human pregnant myometrium

CRH has been implicated to play a key role in the control of human pregnancy and parturition. Large-conductance potassium channels (BKCa) play a pivotal role in the modulation of uterine contractility during pregnancy. The objectives of the present study were to investigate the effect of CRH on BKCa expression in human pregnant myometrial cells. Myometrial tissues were collected at cesarean section from pregnant women not-in-labor (TNL) or in-labor (TL) at term, and myocytes were isolated and cultured. CRH was identified in human pregnant myometrium and mainly expressed in myometrial myocytes. Cultured myometrial cells were able to secrete CRH. In TNL myometrial cells, CRH treatment increased the expression of BKCa α- and β-subunits. CRH receptor type 1 (CRH-R1) antagonist, antalarmin, decreased whereas CRH receptor type 2 (CRH-R2) antagonist, astressin2b, increased the expression of BKCa. CRH-R2 small interfering RNA (siRNA) caused an increase, but CRH-R1 siRNA resulted in a decrease, in BKCa expression. In contrast to TNL cells, CRH exhibited an opposite effect on BKCa expression in TL myometrial cells, i.e. decreased BKCa expression. Antalarmin enhanced but astressin2b reduced BKCa expression. CRH-R2 siRNA decreased whereas CRH-R1 siRNA increased BKCa expression. 1,3-Dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one significantly inhibited the frequency of spontaneous contractions of myometrial strips, and this effect was significantly decreased in TL strips compared with TNL ones. Our data suggest that CRH-R1 and CRH-R2 show differential regulation of BKCa expression. These effects mediated by CRH-R1 and CRH-R2 are changed after the onset of labor. This leads us to suggest that CRH may fine-tune myometrial contractility by modulating the expression of BKCa during pregnancy and labor.

Identification of a myometrial molecular profile for dystocic labor

Background

The most common indication for cesarean section (CS) in nulliparous women is dystocia secondary to ineffective myometrial contractility. The aim of this study was to identify a molecular profile in myometrium associated with dystocic labor.

Methods

Myometrial biopsies were obtained from the upper incisional margins of nulliparous women undergoing lower segment CS for dystocia (n = 4) and control women undergoing CS in the second stage who had demonstrated efficient uterine action during the first stage of labor (n = 4). All patients were in spontaneous (non-induced) labor and had received intrapartum oxytocin to accelerate labor. RNA was extracted from biopsies and hybridized to Affymetrix HuGene U133A Plus 2 microarrays. Internal validation was performed using quantitative SYBR Green Real-Time PCR.

Results

Seventy genes were differentially expressed between the two groups. 58 genes were down-regulated in the dystocia group. Gene ontology analysis revealed 12 of the 58 down-regulated genes were involved in the immune response. These included (ERAP2, (8.67 fold change (FC)) HLA-DQB1 (7.88 FC) CD28 (2.60 FC), LILRA3 (2.87 FC) and TGFBR3 (2.1 FC)) Hierarchical clustering demonstrated a difference in global gene expression patterns between the samples from dystocic and non-dystocic labours. RT-PCR validation was performed on 4 genes ERAP2, CD28, LILRA3 and TGFBR3

Conclusion

These findings suggest an underlying molecular basis for dystocia in nulliparous women in spontaneous labor. Differentially expressed genes suggest an important role for the immune response in dystocic labor and may provide important indicators for new diagnostic assays and potential intrapartum therapeutic targets.

The effects of labor on differential gene expression in parturient women, placentas, and fetuses at term pregnancy

Labor and its associated pain are thought to have unique impacts on parturient women. The goal of this study was to investigate the effects of labor and associated pain on differential gene expression profiles in the maternal, fetal, and placental compartments. We used microarrays to analyze maternal blood (MB), fetal cord blood (CB), and placental tissue samples in pregnant women after term vaginal deliveries (laboring group) and in term pregnant women after scheduled Ceasarean sections (nonlaboring group). The upregulated genes in the MB of the laboring group are involved in cytokine and nuclear factor-kappa B signaling pathways, regulation of the networks of toll-like receptor 4, and suppressor of cytokine signaling 3. Upregulated genes in the CB of the laboring group are involved in responding to stress and stimuli by regulating the network genes of the T-cell receptor beta locus and the FK506 binding protein 8. Differentially expressed genes in the placenta of the laboring group are involved in nitric oxide transport, gas transport, response to hydrostatic pressure, oxygen transport, acute phase responses, and the tumor necrosis factor-mediated signaling pathway, which are important during the transient hypoxemia and hypoperfusion that occur in the placenta during uterine contractions. Interestingly, few of the genes exhibited simultaneous changes in all three compartments, indicating that different pathways and complex interactions may be involved in human labor. In conclusion, human labor and its associated pain elicit unique gene regulatory changes in MB, placenta, and CB.

Effects of progesterone treatment on expression of genes involved in uterine quiescence

An important action of progesterone during pregnancy is to maintain the uterus in a quiescent state and thereby prevent preterm labor. The causes of preterm labor are not well understood, so progesterone action on the myometrium can provide clues about the processes that keep the uterus from contracting prematurely. Accordingly, we have carried out Affymetrix GeneChip analysis of progesterone effects on gene expression in immortalized human myometrial cells cultured from a patient near the end of pregnancy. Progesterone appears to inhibit uterine excitability by a number of mechanisms, including increased expression of calcium and voltage-operated K(+) channels, which dampens the electrical activity of the myometrial cell, downregulation of agents, and receptors involved in myometrial contraction, reduction in cell signal components that lead to increased intracellular Ca(2+) concentrations in response to contractile stimuli, and downregulation of proteins involved in the cross-linking of actin and myosin filaments to produce uterine contractions.

Proteomic analysis of pregnancy-related proteins from pig uterus endometrium during pregnancy

Many important molecular events associated with implantation and development occur within the female reproductive tract, especially within the uterus endometrium, during pregnancy periods. The endometrium includes the mucosal lining of the uterus, which provides a suitable site for implantation and development of a fertilized egg and fetus. To date, the molecular cascades in the uterus endometrium during pregnancy periods in pigs have not been elucidated fully. In this study, we compared the functional regulated proteins in the endometrium during pregnancy periods with those in non-pregnant conditions and investigated changes in expression patterns during pregnancy (days 40, 70, and 93) using two-dimensional gel electrophoresis (2-DE) and western blotting. The functional regulated proteins were identified and discovered from differentially expressed proteins in the uterus endometrium during pregnancy. We discovered 820 protein spots in a proteomic analysis of uterus endometrium tissues with 2-DE gels. We identified 63 of the 98 proteins regulated differentially among non-pregnant and pregnant tissues (matched and unmatched spots). Interestingly, 10 of these 63 proteins are development-, cytoskeleton- and chaperon-related proteins such as transferrin, protein DJ-1, transgelin, galectin-1, septin 2, stathmin 1, cofilin 1, fascin 1, heat shock protein (HSP) 90β and HSP 27. The specific expression patterns of these proteins in the endometrium during pregnancy were confirmed by western blotting. Our results suggest that the expressions of these genes involved in endometrium function and endometrium development from early to late gestation are associated with the regulation of endometrium development for maintaining pregnancy.

Temporal changes in circulating levels of plasma interleukin-8 during peripartum period in Murrah buffaloes (Bubalus bubalis) under subtropical climate

The objective of this study was to elucidate the changes in circulating levels of plasma interleukin-8 (IL-8) during peripartum period in Murrah buffaloes (Bubalus bubalis). IL-8 was estimated in blood plasma of healthy peripartum Murrah buffaloes (n=6) on days ± 30, ± 15, ± 5, ± 3, ± 1 and 0 pre- and postpartum with respect to the day of parturition (day 0) in each of the two different seasons (hot-humid and spring). The mean microclimate Temperature-Humidity Index (THI) during spring season was significantly lower (p<0.01) than the corresponding THI in hot-humid season. In both the seasons, plasma IL-8 remained lower in prepartum period (≤ 46.56 ± 14.08 pg/ml during spring and ≤ 73.18 ± 18.56 pg/ml during hot-humid season) than in the postpartum period (≥ 51.41 ± 13.82 pg/ml during spring and ≥ 84.13 ± 16.97 pg/ml in hot humid season). During spring, the IL-8 levels were significantly higher (P<0.05) on days+5 and +15 postpartum in comparison to the IL-8 levels on days -30, -5, and -3 prepartum. During hot-humid season, IL-8 level was significantly higher (P<0.05) on day +30 as compared to the IL-8 levels on days -30 and -5 prepartum. The correlation between IL-8 and mean microclimate THI was significant (r=0.25, P<0.01). From the results, it is concluded that peripartum period in buffaloes is associated with an inflammatory response leading to significantly higher plasma IL-8 during parturition and postpartum period than in the pre-partum period.

Metabolomics in premature labor: a novel approach to identify patients at risk for preterm delivery

OBJECTIVE

Biomarkers for preterm labor (PTL) and delivery can be discovered through the analysis of the transcriptome (transcriptomics) and protein composition (proteomics). Characterization of the global changes in low-molecular weight compounds which constitute the 'metabolic network' of cells (metabolome) is now possible by using a 'metabolomics' approach. Metabolomic profiling has special advantages over transcriptomics and proteomics since the metabolic network is downstream from gene expression and protein synthesis, and thus more closely reflects cell activity at a functional level. This study was conducted to determine if metabolomic profiling of the amniotic fluid can identify women with spontaneous PTL at risk for preterm delivery, regardless of the presence or absence of intraamniotic infection/inflammation (IAI).

STUDY DESIGN

Two retrospective cross-sectional studies were conducted, including three groups of pregnant women with spontaneous PTL and intact membranes: (1) PTL who delivered at term; (2) PTL without IAI who delivered preterm; and (3) PTL with IAI who delivered preterm. The first was an exploratory study that included 16, 19, and 20 patients in groups 1, 2, and 3, respectively. The second study included 40, 33, and 40 patients in groups 1, 2, and 3, respectively. Amniotic fluid metabolic profiling was performed by combining chemical separation (with gas and liquid chromatography) and mass spectrometry. Compounds were identified using authentic standards. The data were analyzed using discriminant analysis for the first study and Random Forest for the second.

RESULTS

(1) In the first study, metabolomic profiling of the amniotic fluid was able to identify patients as belonging to the correct clinical group with an overall 96.3% (53/55) accuracy; 15 of 16 patients with PTL who delivered at term were correctly classified; all patients with PTL without IAI who delivered preterm neonates were correctly identified as such (19/19), while 19/20 patients with PTL and IAI were correctly classified. (2) In the second study, metabolomic profiling was able to identify patients as belonging to the correct clinical group with an accuracy of 88.5% (100/113); 39 of 40 patients with PTL who delivered at term were correctly classified; 29 of 33 patients with PTL without IAI who delivered preterm neonates were correctly classified. Among patients with PTL and IAI, 32/40 were correctly classified. The metabolites responsible for the classification of patients in different clinical groups were identified. A preliminary draft of the human amniotic fluid metabolome was generated and found to contain products of the intermediate metabolism of mammalian cells and xenobiotic compounds (e.g. bacterial products and Salicylamide).

CONCLUSION

Among patients with spontaneous PTL with intact membranes, metabolic profiling of the amniotic fluid can be used to assess the risk of preterm delivery in the presence or absence of infection/inflammation.

Human effector/initiator gene sets that regulate myometrial contractility during term and preterm labor

OBJECTIVE

Distinct processes govern transition from quiescence to activation during term (TL) and preterm labor (PTL). We sought gene sets that are responsible for TL and PTL, along with the effector genes that are necessary for labor independent of gestation and underlying trigger.

STUDY DESIGN

Expression was analyzed in term and preterm with or without labor (n=6 subjects/group). Gene sets were generated with logic operations.

RESULTS

Thirty-four genes were expressed similarly in PTL/TL but were absent from nonlabor samples (effector set); 49 genes were specific to PTL (preterm initiator set), and 174 genes were specific to TL (term initiator set). The gene ontogeny processes that comprise term initiator and effector sets were diverse, although inflammation was represented in 4 of the top 10; inflammation dominated the preterm initiator set.

CONCLUSION

TL and PTL differ dramatically in initiator profiles. Although inflammation is part of the term initiator and the effector sets, it is an overwhelming part of PTL that is associated with intraamniotic inflammation.

Spatiotemporal expression of α1, α3 and β1 integrin subunits is altered in rat myometrium during pregnancy and labour

Integrins are transmembrane extracellular matrix (ECM) receptors composed of α- and β-subunits. Integrins can cluster to form focal adhesions and, because there is significant ECM remodelling and focal adhesion turnover in the rat myometrium during late pregnancy, we hypothesised that the expression of α1, α3 and β1 integrin subunits in the rat myometrium would be altered at this time to accommodate these processes. Expression of α1 and β1 integrin subunit mRNA was significantly increased on Days 6–23 of pregnancy compared with non-pregnant (NP) and postpartum (PP) time points (P < 0.05). In contrast, α3 integrin subunit mRNA expression was significantly increased on Days 14, 21 and 22 compared with NP, Day 10, 1 day PP and 4 days PP (P < 0.05). A relative gene expression study revealed that, of the integrins studied, the expression of β1 integrin mRNA was highest in pregnant rat myometrium. The α1, α3 and β1 integrin subunit proteins became immunolocalised to myocyte membranes in situ by late pregnancy and labour in both myometrial muscle layers. Increased α1, α3 and β1 integrin gene expression during gestation and the specific detection of these subunits in myocyte membranes during late pregnancy and labour may contribute to the cell–ECM interactions required for the development of a mechanical syncytium.

Changes in global gene expression in rat myometrium in transition from late pregnancy to parturition

The process of parturition involves the complex interplay of factors that change the excitability and contractile activity of the uterus. We have compared the relative gene expression profile of myometrium from rats before parturition (21 days pregnant) and during delivery, using high-density DNA microarray. Of 8,740 sequences available in the array, a total of 3,782 were detected as present. From the sequences that were significantly altered, 59 genes were upregulated and 82 genes were downregulated. We were able to detect changes in genes described to have altered expression level at term, including connexin 43 and 26, cyclooxygenase 2, and oxytocin receptor, as well as novel genes that have been not previously associated with parturition. Quantitative real-time PCR on selected genes further confirmed the microarray data. Here we report for the first time that aquaporin5 (AQP5), a member of the aquaporin water channel family, was dramatically downregulated during parturition (approximately 100-fold by microarray and approximately 50-fold by real-time PCR). The emerging profile highlights biochemical cascades occurring in a period of approximately 36 h that trigger parturition and the initiation of myometrium reverse remodeling postpartum. The microarray analysis uncovered genes that were previously suspected to play a role in parturition. This regulation involves genes from immune/inflammatory response, steroid/lipid metabolism, calcium homeostasis, cell volume regulation, cell signaling, cell division, and tissue remodeling, suggesting the presence of multiple and redundant mechanisms altered in the process of birth.

A novel signaling pathway impact analysis

MOTIVATION

Gene expression class comparison studies may identify hundreds or thousands of genes as differentially expressed (DE) between sample groups. Gaining biological insight from the result of such experiments can be approached, for instance, by identifying the signaling pathways impacted by the observed changes. Most of the existing pathway analysis methods focus on either the number of DE genes observed in a given pathway (enrichment analysis methods), or on the correlation between the pathway genes and the class of the samples (functional class scoring methods). Both approaches treat the pathways as simple sets of genes, disregarding the complex gene interactions that these pathways are built to describe.

RESULTS

We describe a novel signaling pathway impact analysis (SPIA) that combines the evidence obtained from the classical enrichment analysis with a novel type of evidence, which measures the actual perturbation on a given pathway under a given condition. A bootstrap procedure is used to assess the significance of the observed total pathway perturbation. Using simulations we show that the evidence derived from perturbations is independent of the pathway enrichment evidence. This allows us to calculate a global pathway significance P-value, which combines the enrichment and perturbation P-values. We illustrate the capabilities of the novel method on four real datasets. The results obtained on these data show that SPIA has better specificity and more sensitivity than several widely used pathway analysis methods.

AVAILABILITY

SPIA was implemented as an R package available at http://vortex.cs.wayne.edu/ontoexpress/

Do two mutually exclusive gene modules define the phenotypic diversity of mammalian smooth muscle?

Smooth muscle cells (SMCs) are key components of all hollow organs, where they perform contractile, synthetic and other functions. Unlike other muscle cells, SMCs are not terminally differentiated, but exhibit considerable phenotypic variation. Such variation is manifested both across disease states such as asthma and atherosclerosis, and physiological states such as pregnancy and wound healing. While there has been considerable investigation into the diversity of SMCs at the level of morphology and individual biomarkers, less is known about the diversity of SMCs at the level of the transcriptome. To explore this question, we performed an extensive statistical analysis that integrates 200 transcriptional profiles obtained in different SMC phenotypes and reference tissues. Our results point towards a non-trivial hypothesis: that transcriptional variation in different SMC phenotypes is characterized by coordinated differential expression of two mutually exclusive (anti-correlating) gene modules. The first of these modules (C) encodes 19 co-transcribed cell cycle associated genes, whereas the other module (E) encodes 41 co-transcribed extra-cellular matrix components. We propose that the positioning of smooth muscle cells along the C/E axis constitutes an important determinant of SMC phenotypes. In conclusion, our study introduces a new approach to assess phenotypic variation in smooth muscle cells, and is relevant as an example of how integrative bioinformatics analysis can shed light on not only terminal differentiated states but also subtler details in phenotypic variability. It also raises the broader question whether coordinated expression of gene modules is a common mechanism underlying phenotypic variability in mammalian cells.

Multiple signals regulate phospholipase CBeta3 in human myometrial cells

Phospholipase CB3 (PLCB3) serine(1105) (S(1105)), a substrate for multiple protein kinases, represents a potential point of convergence of several signaling pathways in the myometrium. To explore this hypothesis, the regulation of PLCB3-S(1105) phosphorylation (P-S(1105)) was studied in immortalized and primary human myometrial cells. 8-[4-chlorophenylthio] (CPT)-cAMP and calcitonin gene-related peptide (CALCA) transiently increased P-S(1105). Relaxin also stimulated P-S(1105); this effect was partially blocked by the protein kinase A (PRKA) inhibitor, Rp-8-CPT-cAMPS. Oxytocin, which stimulates Galphaq-mediated pathways, also rapidly increased P-S(1105), as did prostaglandin F2alpha and ATP. Oxytocin-stimulated phosphorylation was blocked by protein kinase C (PRKC) inhibitor Go6976 and by pretreatment overnight with a phorbol ester. Cypermethrin, a PP2B phosphatase inhibitor, but not okadaic acid, a PP1/PP2A inhibitor, prolonged the effect of CALCA on P-S(1105), whereas the reverse was the case for the oxytocin-stimulated increase in P-S(1105). PLCB3 was the predominant PLC isoform expressed in the myometrial cells and PLCB3 short hairpin RNA constructs significantly attenuated oxytocin-stimulated increases in intracellular calcium. oxytocin-induced phosphatidylinositol (PI) turnover was inhibited by CPT-cAMP and okadaic acid, but was enhanced by pretreatment with Go6976. CPT-cAMP inhibited oxytocin-stimulated PI turnover in the presence of overexpressed PLCB3, but not overexpressed PLCB3-S(1105)A. These data demonstrate that both negative crosstalk from the cAMP/PRKA pathway and a negative feedback loop in the oxytocin/G protein/PLCB pathway involving PRKC operate in myometrial cells and suggest that different protein phosphatases predominate in mediating P-S(1105) dephosphorylation in these pathways. The integration of multiple signal components at the level of PLCB3 may be important to its function in the myometrium.

Functional genomics of the pregnant uterus: from expectations to reality, a compilation of studies in the myometrium

Background

Studies on the human myometrium have reported on different microarrays containing different sets of genes or ESTs. However each study profiled only a small number of patients due to various constraints. More profiling information would be an addition to our knowledge base of parturition.

Methods

We compiled from five human studies, transcriptional differences between the non pregnant myometrium (NP), preterm myometrium (PTNIL), term myometrium not in labor (TNIL) and term myometrium in labor (TIL). Software modules developed by the Draghici's group at Wayne State University (Detroit, MI, USA) were used to propose a hierarchical list of several KEGG pathways most likely adjusted to changes observed in microarray experiments.

Results

The differential expression of 118 genes could be dispatched in 14 main KEGG pathways that were the most representative of the changes seen in NP and PTNIL, versus TNIL or TIL. Despite the potential of multiple pitfalls inherent to the use of the microarray technology, gene module analysis of the myometrial transcriptome reveals the activation of precise signaling pathways, some of which may have been under evaluated.

Conclusion

The remodelling and maturation processes that the uterus undergoes in pregnancy appear clearly as phenomena which last during the full course of gestation. It is attested by the nature of the main signaling pathways represented, in the comparison of the PTNIL versus TNIL uterus. Comparatively, the onset of labor is a phenomenon which remains less well characterized by these methods of analysis, possibly because it is a phenomenon occurring in too short a window to have been grasped by the studies carried out up to now.

Reductionist and system approaches to study the role of infection in preterm labor and delivery

A substantial number of patients with preterm labor and delivery do not show clinical signs of infection, however, it is the subclinical form which is the main causative factor and often results in premature delivery. The hitherto commonly applied methods of inflammation detection are based either on potentially hazardous amniocentesis or still insufficient inflammation-related protein measurement in the serum or other biological fluids. The advent of new "omics" technologies has led to a paradigm-shift in experimental approach which tends to primarily generate rather than form hypotheses. This has resulted in a surge of wealth of data composed of sets of individual or clusters of new genes and proteins that can be of potential importance as new markers of inflammation leading to preterm labor. It is hoped that as a result of those new methodologies the overall perception of medical research and practice would gradually change from reductionist to systems approach. Despite several successes of reductionism in the diagnosis and treatment of preterm labor it seems that system-based methodology would contribute to a more favorable personalized rather than one-for-all patient assistance. In this review we present the current knowledge on this new attractive field of medical studies with emphasis on early detection of infection related with preterm labor.

Steroid hormone control of myometrial contractility and parturition

The precise temporal control of uterine contractility is essential for the success of pregnancy. For most of pregnancy, progesterone acting through genomic and non-genomic mechanisms promotes myometrial relaxation. At parturition the relaxatory actions of progesterone are nullified and the combined stimulatory actions of estrogens and other factors such as myometrial distention and immune/inflammatory cytokines, transform the myometrium to a highly contractile and excitable state leading to labor and delivery. This review addresses current understanding of how progesterone and estrogens affect the contractility of the pregnancy myometrium and how their actions are coordinated and controlled as part of the parturition cascade.

Control of uterine Ca2+ by membrane voltage: toward understanding the excitation-contraction coupling in human myometrium

Myometrial contractility is a complex and dynamic physiological process that changes substantially during pregnancy and culminates in childbirth. Uterine contractions are initiated by transient rises in cytoplasmic Ca(2+) concentration ([Ca(2+)](i)), which in turn are triggered and controlled by myometrial action potentials. The sequence of events between the action potential generation and the contraction initiation is referred to as excitation-contraction coupling. Hormones and other physiologically active substances affect myometrial contractility by modulating different steps in the excitation-contraction coupling process. It is therefore imperative that we understand that process to understand the regulation of myometrial contractility. The complex action potentials generated by human myometrium result from the activity of many ion channels, transporters, and pumps. Two types of myometrial action potential waveform have been described in the literature: a plateau type and a spike type. Parameters of the myometrial [Ca(2+)](i) transients and contractions differ depending on the type of action potential that triggers them. Some aspects of the excitation-contraction coupling are unique to human myometrium and cannot be found in animal models; some others are common between many species. This article reviews the current state and discusses future directions of physiological research on human myometrial excitation-contraction coupling.

Inflammation of choriodecidua induces tumor necrosis factor alpha-mediated apoptosis of human myometrial cells

The present study investigated the ability of human choriodecidua to induce myometrial cell apoptosis through the secretion of tumor necrosis factor alpha (TNF). The secretion of TNF was evaluated in the culture supernatants of amnion and choriodecidua explants that were exposed to the bacterial endotoxin lipopolysaccharide (LPS) to mimic inflammation. The choriodecidua explants produced more TNF than the amnion explants in response to LPS stimulation, despite the fact that the choriodecidua had lower levels of TLR4 expression. Moreover, conditioned medium obtained from LPS-treated choriodecidua explants, but not that from amnion explants, decreased the number of viable cultured myometrial cells and induced cell apoptosis by inducing the overexpression of the proapoptotic protein BAX and by decreasing the expression of the anti-apoptotic protein BCL2. Neutralization of TNF in the choriodecidua-conditioned medium reversed this effect. Exogenous TNF mimicked LPS-treated choriodecidua-conditioned medium in that it induced myometrial cell apoptosis, reduced BCL2 expression, and increased BAX expression. Using neutralizing antibodies against both subtypes of TNF receptors, we found that only TNFRSF1A participates in TNF-induced myometrial cell apoptosis. Our in vitro model of LPS-induced inflammation of human fetal membrane explants suggests a mechanism by which TNF secreted by choriodecidua governs human myometrial cell apoptosis at the end of pregnancy. These data support the hypothesis that TNF participates in the complex network of signaling processes associated with uterine involution.