In the Murine and Bovine Maternal Mammary Gland Signal Transducer and Activator of Transcription 3 is Activated in Clusters of Epithelial Cells around the Day of Birth.

Signal transducers and activators of transcription (STAT) proteins regulate mammary development. Here we investigate the expression of phosphorylated STAT3 (pSTAT3) in the mouse and cow around the day of birth. We present localised colocation analysis, applicable to other mammary studies requiring identification of spatially congregated events. We demonstrate that pSTAT3-positive events are multifocally clustered in a non-random and statistically significant fashion. Arginase-1 expressing cells, consistent with macrophages, exhibit distinct clustering within the periparturient mammary gland. These findings represent a new facet of mammary STAT3 biology, and point to the presence of mammary sub-microenvironments.

ADAMTS4 is a crucial proteolytic enzyme for versican cleavage in the amnion at parturition.

Hyalectan cleavage may play an important role in extracellular matrix remodeling. However, the proteolytic enzyme responsible for hyalectan degradation for fetal membrane rupture at parturition remains unknown. Here, we reveal that versican (VCAN) is the major hyalectan in the amnion, where its cleavage increases at parturition with spontaneous rupture of membrane. We further reveal that ADAMTS4 is a crucial proteolytic enzyme for VCAN cleavage in the amnion. Inflammatory factors may enhance VCAN cleavage by inducing ADAMTS4 expression and inhibiting ADAMTS4 endocytosis in amnion fibroblasts. In turn, versikine, the VCAN cleavage product, induces inflammatory factors in amnion fibroblasts, thereby forming a feedforward loop between inflammation and VCAN degradation. Mouse studies show that intra-amniotic injection of ADAMTS4 induces preterm birth along with increased VCAN degradation and proinflammatory factors abundance in the fetal membranes. Conclusively, there is enhanced VCAN cleavage by ADAMTS4 in the amnion at parturition, which can be reenforced by inflammation.

Disruption of the SP-A/SP-R210L (MYO18Aα) pathway prolongs gestation and reduces fetal survival during lipopolysaccharide-induced parturition in late gestation.

Prolonged labor can lead to infection, fetal distress, asphyxia, and life-threatening harm to both the mother and the baby. Surfactant protein A (SP-A) was shown to contribute to the maintenance of pregnancy and timing of term labor. SP-A modulates the stoichiometric expression of the SP-R210L and SP-R210S isoforms of the SP-R210 receptor on alveolar macrophages (AMs). Lack of SP-R210L dysregulates macrophage inflammatory responses. We asked whether SP-A alters normal and inflammation-induced parturition through SP-R210 using SP-A- and SP-R210L-deficient mice. Labor and delivery of time-pregnant mice were monitored in real time using a time-lapse infrared camera. Intrauterine injection with either vehicle or Escherichia coli lipopolysaccharide (LPS) on embryonic (E) day 18.5 post coitus was used to assess the effect of gene disruption in chorioamnionitis-induced labor. We report that either lack of SP-A or disruption of SP-R210L delays parturition by 0.40 and 0.55 days compared with controls, respectively. LPS induced labor at 0.60, 1.01, 0.40, 1.00, and 1.31 days earlier than PBS controls in wild type (WT), SP-A-deficient, littermate controls, heterozygous, and homozygous SP-R210L-deficient mice, respectively. Lack of SP-A reduced litter size in PBS-treated mice, whereas the total number of pups delivered was similar in all LPS-treated mice. The number of live pups, however, was significantly reduced by 50%-70% in SP-A and SP-R210L-deficient mice compared with controls. Differences in gestational length were not associated with intrauterine growth restriction. The present findings support the novel concept that the SP-A/SP-R210 pathway modulates timely labor and delivery and supports fetal lung barrier integrity during fetal-to-neonatal transition in term pregnancy.NEW & NOTEWORTHY To our knowledge, this study is the first to report that SP-A prevents delay of labor and inflammation-induced stillbirth through the receptor SP-R210L.

IL-33/ST2 axis of human amnion fibroblasts participates in inflammatory reactions at parturition.

BACKGROUND: Inflammation of the fetal membranes is an indispensable event of labor onset at both term and preterm birth. Interleukin-33 (IL-33) is known to participate in inflammation via ST2 (suppression of tumorigenicity 2) receptor as an inflammatory cytokine. However, it remains unknown whether IL-33/ST2 axis exists in human fetal membranes to promote inflammatory reactions in parturition. METHODS: The presence of IL-33 and ST2 and their changes at parturition were examined with transcriptomic sequencing, quantitative real-time polymerase chain reaction, Western blotting or immunohistochemistry in human amnion obtained from term and preterm birth with or without labor. Cultured primary human amnion fibroblasts were utilized to investigate the regulation and the role of IL-33/ST2 axis in the inflammation reactions. A mouse model was used to further study the role of IL-33 in parturition. RESULTS: Although IL-33 and ST2 expression were detected in both epithelial and fibroblast cells of human amnion, they are more abundant in amnion fibroblasts. Their abundance increased significantly in the amnion at both term and preterm birth with labor. Lipopolysaccharide, serum amyloid A1 and IL-1ß, the inflammatory mediators pertinent to labor onset, could all induce IL-33 expression through NF-κB activation in human amnion fibroblasts. In turn, via ST2 receptor, IL-33 induced the production of IL-1ß, IL-6 and PGE2 in human amnion fibroblasts via the MAPKs-NF-κB pathway. Moreover, IL-33 administration induced preterm birth in mice. CONCLUSION: IL-33/ST2 axis is present in human amnion fibroblasts, which is activated in both term and preterm labor. Activation of this axis leads to increased production of inflammatory factors pertinent to parturition, and results in preterm birth. Targeting the IL-33/ST2 axis may have potential value in the treatment of preterm birth.

Amnion-derived serum amyloid A1 participates in sterile inflammation of fetal membranes at parturition.

OBJECTIVES: Sterile inflammation of fetal membranes is an indispensable event of normal parturition. However, triggers of sterile inflammation are not fully resolved. Serum amyloid A1 (SAA1) is an acute phase protein produced primarily by the liver. Fetal membranes can also synthesize SAA1 but its functions are not well defined. Given the role of SAA1 in the acute phase response to inflammation, we postulated that SAA1 synthesized in the fetal membranes may be a trigger of local inflammation at parturition. METHODS: The changes of SAA1 abundance in parturition were studied in the amnion of human fetal membranes. The role of SAA1 in chemokine expression and leukocyte chemotaxis was examined in cultured human amnion tissue explants as well as primary human amnion fibroblasts. The effects of SAA1 on monocytes, macrophages and dendritic cells were investigated in cells derived from a human leukemia monocytic cell line (THP-1). RESULTS: SAA1 synthesis increased significantly in human amnion at parturition. SAA1 evoked multiple chemotaxis pathways in human amnion fibroblasts along with upregulation of a series of chemokines via both toll-like receptor 4 (TLR4) and formyl peptide receptor 2 (FPR2). Moreover, SAA1-conditioned medium of cultured amnion fibroblasts was capable of chemoattracting virtually all types of mononuclear leukocytes, particularly monocytes and dendritic cells, which reconciled with the chemotactic activity of conditioned medium of cultured amnion tissue explants collected from spontaneous labor. Furthermore, SAA1 could induce the expression of genes associated with inflammation and extracellular matrix remodeling in monocytes, macrophages and dendritic cells derived from THP-1. CONCLUSIONS: SAA1 is a trigger of sterile inflammation of the fetal membranes at parturition.

Circumvention of luteolysis reveals parturition pathways in mice dependent upon innate type 2 immunity.

Although mice normally enter labor when their ovaries stop producing progesterone (luteolysis), parturition can also be triggered in this species through uterus-intrinsic pathways potentially analogous to the ones that trigger parturition in humans. Such pathways, however, remain largely undefined in both species. Here, we report that mice deficient in innate type 2 immunity experienced profound parturition delays when manipulated endocrinologically to circumvent luteolysis, thus obliging them to enter labor through uterus-intrinsic pathways. We found that these pathways were in part driven by the alarmin IL-33 produced by uterine interstitial fibroblasts. We also implicated important roles for uterine group 2 innate lymphoid cells, which demonstrated IL-33-dependent activation prior to labor onset, and eosinophils, which displayed evidence of elevated turnover in the prepartum uterus. These findings reveal a role for innate type 2 immunity in controlling the timing of labor onset through a cascade potentially relevant to human parturition.

Ceramide on the road to insulin resistance and immunometabolic disorders in transition dairy cows: driver or passenger?

Dairy cows must undergo profound metabolic and endocrine adaptations during their transition period to meet the nutrient requirements of the developing fetus, parturition, and the onset of lactation. Insulin resistance in extrahepatic tissues is a critical component of homeorhetic adaptations in periparturient dairy cows. However, due to increased energy demands at calving that are not followed by a concomitant increase in dry matter intake, body stores are mobilized, and the risk of metabolic disorders dramatically increases. Sphingolipid ceramides involved in multiple vital biological processes, such as proliferation, differentiation, apoptosis, and inflammation. Three typical pathways generate ceramide, and many factors contribute to its production as part of the cell's stress response. Based on lipidomic profiling, there has generally been an association between increased ceramide content and various disease outcomes in rodents. Emerging evidence shows that ceramides might play crucial roles in the adaptive metabolic alterations accompanying the initiation of lactation in dairy cows. A series of studies also revealed a negative association between circulating ceramides and systemic insulin sensitivity in dairy cows experiencing severe negative energy balance. Whether ceramide acts as a driver or passenger in the metabolic stress of periparturient dairy cows is an unknown but exciting topic. In the present review, we discuss the potential roles of ceramides in various metabolic dysfunctions and the impacts of their perturbations. We also discuss how this novel class of bioactive sphingolipids has drawn interest in extrahepatic tissue insulin resistance and immunometabolic disorders in transition dairy cows. We also discuss the possible use of ceramide as a new biomarker for predicting metabolic diseases in cows and highlight the remaining problems.

Identification of a Feed-Forward Loop Between 15(S)-HETE and PGE2 in Human Amnion at Parturition.

Human parturition is associated with massive arachidonic acid (AA) mobilization in the amnion, indicating that large amounts of AA-derived eicosanoids are required for parturition. Prostaglandin E2 (PGE2) synthesized from the cyclooxygenase (COX) pathway is the best characterized AA-derived eicosanoid in the amnion which plays a pivotal role in parturition. The existence of any other pivotal AA-derived eicosanoids involved in parturition remains elusive. Here, we screened such eicosanoids in human amnion tissue with AA-targeted metabolomics and studied their role and synthesis in parturition by using human amnion fibroblasts and a mouse model. We found that lipoxygenase (ALOX) pathway-derived 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) and its synthetic enzymes ALOX15 and ALOX15B were significantly increased in human amnion at parturition. Although 15(S)-HETE is ineffective on its own, it potently potentiated the activation of NF-κB by inflammatory mediators including lipopolysaccharide, interleukin-1ß, and serum amyloid A1, resulting in the amplification of COX-2 expression and PGE2 production in amnion fibroblasts. In turn, we determined that PGE2 induced ALOX15/15B expression and 15(S)-HETE production through its EP2 receptor-coupled PKA pathway, thereby forming a feed-forward loop between 15(S)-HETE and PGE2 production in the amnion at parturition. Our studies in pregnant mice showed that 15(S)-HETE injection induced preterm birth with increased COX-2 and PGE2 abundance in the fetal membranes and placenta. Conclusively, 15(S)-HETE is identified as another crucial parturition-pertinent AA-derived eicosanoid in the amnion, which may form a feed-forward loop with PGE2 in parturition. Interruption of this feed-forward loop may be of therapeutic value for the treatment of preterm birth.

Cortisol Stimulates Local Progesterone Withdrawal Through Induction of AKR1C1 in Human Amnion Fibroblasts at Parturition.

Fetal membrane activation is seen as being one of the crucial triggering components of human parturition. Increased prostaglandin E2 (PGE2) production, a common mediator of labor onset in virtually all species, is recognized as one of the landmark events of membrane activation. Fetal membranes are also equipped with a high capacity of cortisol regeneration by 11ß-hydroxysteroid dehydrogenase 1 (11ß-HSD1), and the cortisol regenerated potently induces PGE2 synthesis, an effect normally suppressed by progesterone during gestation. There is no precipitous decline of progesterone synthesis in human parturition. It is intriguing how this suppression is lifted in parturition. Here, we investigated this issue by using human amnion tissue and primary amnion fibroblasts which synthesize the most PGE2 in the fetal membranes. Results showed that the expression of 11ß-HSD1 and aldo-keto reductase family 1 member C1 (AKR1C1), a progesterone-inactivating enzyme, increased in parallel in human amnion tissue with gestational age toward the end of gestation and at parturition. Cortisol induced AKR1C1 expression via the transcription factor CCAAT enhancer binding protein δ (C/EBPδ) in amnion fibroblasts. Inhibition of AKR1C1 not only blocked progesterone catabolism induced by cortisol, but also enhanced the suppression of cortisol-induced cyclooxygenase-2 (COX-2) expression by progesterone in amnion fibroblasts. In conclusion, our results indicate that cortisol regenerated in the fetal membranes triggers local progesterone withdrawal through enhancement of AKR1C1-mediated progesterone catabolism in amnion fibroblasts, so that the suppression of progesterone on the induction of COX-2 expression and PGE2 synthesis by cortisol can be lifted for parturition.

Serum amyloid A, a host-derived DAMP in pregnancy?

Serum amyloid A (SAA) is one of the acute phase proteins released primarily from the liver in response to infection, inflammation and trauma. Emerging evidence indicates that SAA may function as a host-derived damage-associated molecular pattern (DAMP) protein to sense danger signals in pregnancy. The plasma SAA levels in maternal circulation are significantly increased in normal parturition, particularly in postpartum, as well as in gestational disorders such as premature preterm rupture of membranes, pre-eclampsia, gestational diabetes, and recurrent spontaneous abortion. It is likely that SAA acts as a non-specific DAMP molecule in response to inflammation and trauma experienced under these conditions. Notably, SAA can also be synthesized locally in virtually all gestational tissues. Within these gestational tissues, under the induction by bacterial products, pro-inflammatory cytokines and stress hormone glucocorticoids, SAA may exert tissue-specific effects as a toll-like receptor 4 (TLR4)-sensed DAMP molecule. SAA may promote parturition through stimulation of inflammatory reactions via induction of pro-inflammatory cytokines, chemokines, adhesion molecules and prostaglandins in the uterus, fetal membranes and placenta. In the fetal membranes, SAA may also facilitate membrane rupture through induction of matrix metalloproteases (MMPs)- and autophagy-mediated collagen breakdown and attenuation of lysyl oxidase-mediated collagen cross-linking. SAA synthesized in extravillous trophoblasts may promote their invasiveness into the endometrium in placentation. Here, we summarized the current understanding of SAA in pregnancy with an aim to stimulate in-depth investigation of SAA in pregnancy, which may help better understand how inflammation is initiated in gestational tissues in both normal and abnormal pregnancies.

The role of progesterone receptor isoforms in the myometrium.

Myometrial contraction is stringently controlled throughout pregnancy and parturition. Progesterone signaling, effecting through the progesterone receptor (PR), is pivotal in modulating uterine activity. Evidence has shown that two major PR isoforms, PR-A and PR-B, have distinct activities on gene regulation, and the ratio between these isoforms determines the contractility of the myometrium at different gestational stages. Herein, we focus on the regulation of PR activity in the myometrium, especially the differential actions of the two PR isoforms, which maintain uterine quiescence during pregnancy and regulate the switch to a contractile state at the onset of labor. To demonstrate the PR regulatory network and its mechanisms of actions on myometrial activity, we summarized the findings into three parts: Regulation of PR Expression and Isoform Levels, Progesterone Receptor Interacting Factors, and Biological Processes Regulated by Myometrial Progesterone Receptor Isoforms. Recent genomic and epigenomic data, from human specimens and mouse models, are recruited to support the existing knowledge and offer new insights and future directions in myometrial biology.

Dietary L-Carnitine Affects Leukocyte Count and Function in Dairy Cows Around Parturition.

In early lactation, an energy deficit leading to a negative energy balance (NEB) is associated with increased susceptibility to disease and has been shown to be an important factor during transition in dairy cows. L-carnitine as a key factor in the mitochondrial transport of fatty acids and subsequently for ß-oxidation and energy release is known to modulate mitochondrial biogenesis and thus influence metabolism and immune system. In the current study, we characterized hematological changes around parturition and investigated the potential effects of dietary L-carnitine supplementation on immune cell functions. For this approach, dairy cows were assigned either to a control (CON, n = 30) or an L-carnitine group [CAR, n = 29, 25 g rumen-protected L-carnitine per cow and day (d)]. Blood samples were taken from d 42 ante partum (ap) until d 110 post-partum (pp), with special focus and frequent sampling from 0.5 to72 h post-calving to clarify the impact of L-carnitine supplementation on leukocyte count, formation of reactive oxygen species (ROS) in polymorphonuclear cells (PMN) and peripheral mononuclear cells (PBMC) and their phagocytosis activity. Blood cortisol concentration and the capacity of PBMC proliferation was also investigated. All populations of leukocytes were changed during the peripartal period, especially granulocytes showed a characteristic increase up to 4 h pp. L-carnitine supplementation resulted in increased levels of eosinophils which was particularly pronounced one day before to 4 h pp, indicating a possible enhanced support for tissue repair and recovery. Non-supplemented cows showed a higher phagocytic activity in PBMC as well as a higher phagocytic capacity of PMN during the most demanding period around parturition, which may relate to a decrease in plasma levels of non-esterified fatty acids reported previously. L-carnitine, on the other hand, led to an increased efficiency to form ROS in stimulated PMN. Finally, a short period around calving proved to be a sensitive period in which L-carnitine administration was effective.

A single-cell atlas of the myometrium in human parturition.

Parturition is a well-orchestrated process characterized by increased uterine contractility, cervical ripening, and activation of the chorioamniotic membranes; yet, the transition from a quiescent to a contractile myometrium heralds the onset of labor. However, the cellular underpinnings of human parturition in the uterine tissues are still poorly understood. Herein, we performed a comprehensive study of the human myometrium during spontaneous term labor using single-cell RNA sequencing (scRNA-Seq). First, we established a single-cell atlas of the human myometrium and unraveled the cell type-specific transcriptomic activity modulated during labor. Major cell types included distinct subsets of smooth muscle cells, monocytes/macrophages, stromal cells, and endothelial cells, all of which communicated and participated in immune (e.g., inflammation) and nonimmune (e.g., contraction) processes associated with labor. Furthermore, integrating scRNA-Seq and microarray data with deconvolution of bulk gene expression highlighted the contribution of smooth muscle cells to labor-associated contractility and inflammatory processes. Last, myometrium-derived single-cell signatures can be quantified in the maternal whole-blood transcriptome throughout pregnancy and are enriched in women in labor, providing a potential means of noninvasively monitoring pregnancy and its complications. Together, our findings provide insights into the contributions of specific myometrial cell types to the biological processes that take place during term parturition.

Fetal inflammatory response at the fetomaternal interface: A requirement for labor at term and preterm.

Human parturition at term and preterm is an inflammatory process synchronously executed by both fetomaternal tissues to transition them from a quiescent state t an active state of labor to ensure delivery. The initiators of the inflammatory signaling mechanism can be both maternal and fetal. The placental (fetal)-maternal immune and endocrine mediated homeostatic imbalances and inflammation are well reported. However, the fetal inflammatory response (FIR) theories initiated by the fetal membranes (amniochorion) at the choriodecidual interface are not well established. Although immune cell migration, activation, and production of proparturition cytokines to the fetal membranes are reported, cellular level events that can generate a unique set of inflammation are not well discussed. This review discusses derangements to fetal membrane cells (physiologically and pathologically at term and preterm, respectively) in response to both endogenous and exogenous factors to generate inflammatory signals. In addition, the mechanisms of inflammatory signal propagation (fetal signaling of parturition) and how these signals cause immune imbalances at the choriodecidual interface are discussed. In addition to maternal inflammation, this review projects FIR as an additional mediator of inflammatory overload required to promote parturition.

Influence of ω3 fatty acids on maternal behavior and brain oxytocin in the murine perinatal period.

INTRODUCTION: Perinatal women often experience mood disorders and postpartum depression due to the physical load and the rapid changes in hormone levels caused by pregnancy, childbirth, and nursing. When the mother's emotions become unstable, their parental behavior (maternal behavior) may decline, the child's attachment may weaken, and the formation of mother-child bonding can become hindered. As a result, the growth of the child may be adversely affected. The objective of this study was to investigate the effect of ω3 fatty acid deficiency in the perinatal period on maternal behavior and the oxytocin concentration and fatty acid composition in brain tissue. MATERIALS AND METHODS: Virgin female C57BL/6 J mice fed a ω3 fatty acid-deficient (ω3-Def) or adequate (ω3-Adq) diet were mated for use in this study. To assess maternal behavior, nest shape was evaluated at a fixed time from gestational day (GD) 15 to postpartum day (PD) 13, and a retrieval test was conducted on PD 3. For neurochemical measurement, brains were removed from PD 1-6 dams and hippocampal fatty acids and hypothalamic oxytocin concentrations were assessed. RESULTS: Peripartum nest shape scores were similar to those reported previously (Harauma et al., 2016); nests in the ω3-Def group were small and of poor quality whereas those in the ω3-Adq group were large and elaborate. The inferiority of nest shape in the ω3-Def group continued from PD 0-7. In the retrieval test performed on PD 3, dams in the ω3-Def group took longer on several parameters compared with those in the ω3-Adq group, including time to make contact with pups (sniffing time), time to start retrieving the next pup (interval time), and time to retrieve the last pup to the nest (grouping time). Hypothalamic oxytocin concentrations on PD 1-6 were lower in the ω3-Def group than in the ω3-Adq group. DISCUSSION: Our data show that ω3 fatty acid deficiency reduces maternal behavior, a state that continued during pup rearing. This was supported by the observed decrease in hypothalamic oxytocin concentration in the ω3-Def group. These results suggest that ω3 fatty acid supplementation during the perinatal period is not only effective in delivering ω3 fatty acids to infants but is also necessary to activate high-quality parental behavior in mothers.

Consumption of a Low Carbohydrate Diet in Overweight or Obese Pregnant Women Is Associated with Longer Gestation of Pregnancy.

Studies of obstetric outcomes in women consuming low-carbohydrate diets have reported conflicting results. Most studies have defined low-carbohydrate diets by the percentage that carbohydrates contribute to overall energy intake, rather than by an absolute amount in grams per day (g/d). We hypothesised that a low absolute carbohydrate diet affects obstetric outcomes differently than a low percentage carbohydrate diet. Dietary data were collected from overweight or obese women in the Study of Probiotic IN Gestational diabetes at 16- and 28-weeks' gestation. Obstetric outcomes were compared between women whose carbohydrate intake was in the lowest quintile vs quintiles 2-5. Mean gestation was increased in women whose absolute carbohydrate intake was in the lowest quintile at 16 and at both 16- and 28-weeks' gestation compared with all other women (16: 39.7 vs. 39.1 weeks, p = 0.008; 16 and 28: 39.8 vs. 39.1, p = 0.005). In linear regression analysis, a low absolute carbohydrate intake at 16 and at 28 weeks' gestation was associated with increased gestation at delivery (16: p = 0.04, adjusted R2 = 0.15, 28: p = 0.04, adjusted R2 = 0.17). The coefficient of beta at 16 weeks' gestation was 0.50 (95% CI 0.03-0.98) and at 28 weeks' gestation was 0.51 (95%CI 0.03-0.99) meaning that consumption of a low absolute carbohydrate diet accounted for an extra 3.5 days in gestational age. This finding was not seen in women whose percentage carbohydrate intake was in the lowest quintile. Low-carbohydrate consumption in pregnancy is associated with increased gestational age at delivery.

Integrated Proteotranscriptomics of Human Myometrium in Labor Landscape Reveals the Increased Molecular Associated With Inflammation Under Hypoxia Stress.

During labor, a variety of coordinated physiological and biochemical events cause the myometrium to transition from a quiescent to contractile state; the molecular mechanisms responsible for this transition, however, remain unclear. To better understand this transition at a molecular level, the global transcriptome and proteome of human myometrial samples in labor and those not in labor were investigated through RNA sequencing (RNA-seq) and quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) via data-independent acquisition (DIA) and parallel reaction monitoring (PRM) methods. Furthermore, an integrated proteotranscriptomic analysis was performed to explore biological processes and pathway alterations during labor; this analysis identified 1,626 differentially expressed mRNAs (1,101 upregulated, 525 downregulated) and 135 differentially expressed proteins (97 upregulated, 38 downregulated) in myometrium between nonlabor and in labor groups. The comprehensive results of these analyses showed that the upregulated mRNAs and proteins increased inflammation under hypoxia stress in the myometrium under labor, and related proteins and cytokines were validated by PRM and Luminex assays. Our study confirmed the biological process of inflammation and hypoxia in laboring myometrium at the transcriptome and proteome levels and provided recourse to discover new molecular and biological changes during labor.

Transcription factors regulated by cAMP in smooth muscle of the myometrium at human parturition.

Cyclic adenosine monophosphate (cAMP) contributes to maintenance of a quiescent (relaxed) state in the myometrium (i.e. uterine smooth muscle) during pregnancy, which most commonly has been attributed to activation of protein kinase A (PKA). PKA-mediated phosphorylation of cytosolic contractile apparatus components in myometrial smooth muscle cells (mSMCs) are known to promote relaxation. Additionally, PKA also regulates nuclear transcription factor (TF) activity to control expression of genes important to the labour process; these are mostly involved in actin-myosin interactions, cell-to-cell connectivity and inflammation, all of which influence mSMC transition from a quiescent to a contractile (pro-labour) phenotype. This review focuses on the evidence that cAMP modulates the activity of TFs linked to pro-labour gene expression, predominantly cAMP response element (CRE) binding TFs, nuclear factor κB (NF-κB), activator protein 1 (AP-1) family and progesterone receptors (PRs). This review also considers the more recently described exchange protein directly activated by cAMP (EPAC) that may oppose the pro-quiescent effects of PKA, as well as explores findings from other cell types that have the potential to be of novel relevance to cAMP action on TF function in the myometrium.

SAA1 regulates pro-labour mediators in term labour by activating YAP pathway.

Term labour is associated with activation of inflammation which results in myometrial contractility, cervical ripening and decidual/membrane rupture. Serum amyloid A1 (SAA1) is an acute response protein, whose role and underlying regulatory mechanisms in human labour remain unknown. In this study, we found that the mRNA and protein expression of SAA1 in human myometrium at term was increased in labouring tissues compared to non-labouring tissues. In addition, the expression of SAA1 was significantly increased in human primary myometrial cells treated with the pro-inflammatory cytokines interleukin-1 beta (IL-1ß) or tumour necrosis factor-alpha (TNF-α). Knockdown of SAA1 using siRNA (siSAA1) resulted in a significant reduction in the expression and secretion of pro-inflammatory cytokines (IL8, IL6), chemokines (CXCL5, CCL2), adhesion molecules (ICAM1, ICAM5) and contraction-associated factors (COX2, PGE2). Mechanistically, the effects of SAA1 were mediated through activation of the Yes-associated protein (YAP) pathway. There was a decrease in the protein expression of phosphorylated YAP (pYAP) after treatment of siSAA1-transfected human primary myometrial cells with IL-1ß or TNF-α. Moreover, enhanced expression of YAP reversed the effect of siSAA1 on pro-labour mediators. In conclusion, these experiments demonstrated that SAA1 accelerates the inflammatory response associated with parturition by activating YAP pathway, which may be a novel understanding of the molecular mechanism of labour onset.

Maternal Myometrium Metabolomic Profiles in Labor: Preliminary Results.

INTRODUCTION: Parturition involves multiple complex metabolic processes that supply essential metabolites to facilitate fetal delivery. Little is known about the dynamic metabolic responses during labor. OBJECTIVE: To profile the changes of myometrial metabolites between nonlabor and labor. METHODS: The study involved 30 women in nonlabor and 30 in labor who underwent cesarean section. The characteristics of myometrial metabolite changes during parturition were explored through untargeted metabolomic analysis. Data were analyzed by multivariate and univariate statistical analysis. RESULTS: Partial least squares-discriminant analysis plots significantly differentiated between the groups. In total, 392 metabolites were significantly distinct between the groups, among which lipid molecules were predominant. A 75% increase in fatty acids, 67% increase in fatty acid carnitines, 66% increase in glycerophospholipids, 83% increase in mono- and diacylglycerols, and 67% decrease in triacyclglycerols were observed in the patients during labor. Most glucose, amino acid, and steroid hormone metabolism also slightly increased in labor. CONCLUSIONS: An increase in lipolysis, fatty acid oxidation, amino acid catabolism, and steroid hormone metabolism was observed during parturition. The change of lipolysis and fatty acid oxidation is the most significant.