Inflammatory mediators and cervical ripening

Expression patterns and distribution of aquaporin water channels in cervix as a possible mechanism for cervical patency in bitches affected by pyometra

Pyometra is a life-threatening disease, the severity of which depends on cervical patency status. This study investigated cervical inflammation status as well as the expression patterns and localization of aquaporin (AQP1, AQP2, AQP3, AQP5, and AQP9), and hormone receptors in cervical tissue that influences canine pyometra. Of the 36 animals enrolled in the study, 24 were diagnosed with pyometra and separated into two groups: open cervix pyometra and close cervix pyometra, while 12 healthy animals presented for elective ovariohysterectomies were allocated into the control group. Surgical treatment was performed for treatment of pyometra. After each operation, cervix samples were collected and analyzed for AQP and hormone receptor expression patterns determined by qPCR and protein expression by means of immunohistochemistry. Blood samples were also collected to determine serum progesterone concentrations. AQP9 expression was downregulated approximately 3-fold while and PGR expression was downregulated more than 2 fold in both pyometra groups compared to the control group. AQP3 and AQP5 gene expression levels were upregulated more than 3 fold in the open-cervix pyometra group than the closed-cervix pyometra group (P < 0.05). This is the first study to describe the expression patterns and immunolocalization of AQPs in canine cervical tissue based on pyometra patency status and to report AQP3 and AQP5 expression in cervical tissue linked to cervical patency.

Assessing the Efficacy and Safety of Misoprostol Prior to Hysteroscopy in Women with Difficult Cervix: A Systematic Review and Meta-Analysis

Background/Objectives: Hysteroscopy has been used as both a diagnostic and therapeutic tool for intrauterine pathologies under direct visualization. However, this procedure may be associated with an increased risk of complications during entry, which can be reduced by cervical ripening before the operation. The efficacy of misoprostol in this context is influenced by factors such as estrogen levels, parity, and the mode of previous deliveries. This study aimed to assess the efficacy and safety of misoprostol in women with a challenging cervix while mitigating the influence of confounding variables. Methods: Three electronic databases, namely PubMed, Scopus, and ISI Web of Science, were searched until 14 May 2024. Randomized controlled trials focusing on postmenopausal patients, nulliparous women, and multiparous women with no prior history of vaginal delivery, undergoing hysteroscopy were included. The cervical width, time needed for cervical dilation, and the need for additional dilatation alongside the complications and adverse effects from all included studies were collected and analyzed using R (version 4.2.3). Results: Seven studies on premenopausal women and three on postmenopausal women were included. In premenopausal women, misoprostol significantly increased cervical width compared to placebo (SMD = 2.2, 95% CI 0.9 to 3.4) and reduced the need for additional cervical dilatation (OR = 0.36, 95% CI 0.17 to 0.74). No significant difference was found in the time required for cervical dilation between misoprostol and placebo groups. In postmenopausal women, misoprostol did not significantly affect cervical width compared to placebo (SMD = -0.55, 95% CI -1.3 to 0.21). Conclusions: Misoprostol is beneficial for cervical dilation in premenopausal women without a prior history of vaginal delivery but less effective in postmenopausal patients. While associated with postoperative risks, it reduces hysteroscopy-related complications. Future research should address discrepancies by controlling the confounding variables like menopausal status, parity, and mode of delivery to enhance the understanding of misoprostol's effects and pinpoint the specific patient populations that would derive the greatest benefits from its use.

Gestation-dependent increase in cervicovaginal pro-inflammatory cytokines and cervical extracellular matrix proteins is associated with spontaneous preterm delivery within 2 weeks of index assessment in South African women

Introduction

Inflammation-induced remodelling of gestational tissues that underpins spontaneous preterm birth (sPTB, delivery < 37 weeks' gestation) may vary by race and context. To explore relationships between markers of these pathological processes, we (a) characterised the cervicovaginal fluid (CVF) cytokine profiles of pregnant South African women at risk of PTB; (b) determined CVF matrix-metalloproteinase-9 (MMP-9) and its regulator tissue inhibitor of metalloproteinase-1 (TIMP-1); and (c) explored the predictive potential of these markers for sPTB.

Method of study

The concentrations of 10 inflammatory cytokines and MMP-9 and TIMP-1 were determined by ELISA in CVF samples from 47 non-labouring women at high risk of PTB. We studied CVF sampled at three gestational time points (GTPs): GTP1 (20-22 weeks, n = 37), GTP2 (26-28 weeks, n = 40), and GTP3 (34-36 weeks, n = 29) and analysed for changes in protein concentrations and predictive capacities (area under the ROC curve (AUC) and 95% confidence interval (CI)) for sPTB.

Results

There were 11 (GTP1), 13 (GTP2), and 6 (GTP3) women who delivered preterm within 85.3 ± 25.9, 51.3 ± 15.3, and 11.8 ± 7.5 (mean ± SD) days after assessment, respectively. At GTP1, IL-8 was higher (4-fold, p = 0.02), whereas GM-CSF was lower (~1.4-fold, p = 0.03) in the preterm compared with term women with an average AUC = 0.73. At GTP2, IL-1β (18-fold, p < 0.0001), IL-8 (4-fold, p = 0.03), MMP-9 (17-fold, p = 0.0007), MMP-9/TIMP-1 ratio (9-fold, p = 0.004), and MMP-9/GM-CSF ratio (87-fold, p = 0.005) were higher in preterm compared with term women with an average AUC = 0.80. By contrast, IL-10 was associated with term delivery with an AUC (95% CI) = 0.75 (0.55-0.90). At GTP3, IL-1β (58-fold, p = 0.0003), IL-8 (12-fold, p = 0.002), MMP-9 (296-fold, p = 0.03), and TIMP-1 (35-fold, p = 0.01) were higher in preterm compared with term women with an average AUC = 0.85. Elevated IL-1β was associated with delivery within 14 days of assessment with AUC = 0.85 (0.67-0.96). Overall, elevated MMP-9 at GTP3 had the highest (13.3) positive likelihood ratio for distinguishing women at risk of sPTB. Lastly, a positive correlation between MMP-9 and TIMP-1 at all GTPs (ρ ≥ 0.61, p < 0.01) for women delivering at term was only observed at GTP1 for those who delivered preterm (ρ = 0.70, p < 0.03).

Conclusions

In this cohort, sPTB is associated with gestation-dependent increase in pro-inflammatory cytokines, decreased IL-10 and GM-CSF, and dysregulated MMP-9-TIMP-1 interaction. Levels of cytokine (especially IL-1β) and ECM remodelling proteins rise significantly in the final 2 weeks before the onset of labour when sPTB is imminent. The signalling mechanisms for these ECM remodelling observations remain to be elucidated.

The Role of the NLRP3 Inflammasome in the Molecular and Biochemical Mechanisms of Cervical Ripening: A Comprehensive Review

The uterine cervix is one of the key factors involved in ensuring a proper track of gestation and labor. At the end of the gestational period, the cervix undergoes extensive changes, which can be summarized as a transformation from a non-favorable cervix to one that is soft and prone to dilation. During a process called cervical ripening, fundamental remodeling of the cervical extracellular matrix (ECM) occurs. The cervical ripening process is a derivative of many interlocking and mutually driving biochemical and molecular pathways under the strict control of mediators such as inflammatory cytokines, nitric oxide, prostaglandins, and reactive oxygen species. A thorough understanding of all these pathways and learning about possible triggering factors will allow us to develop new, better treatment algorithms and therapeutic goals that could protect women from both dysfunctional childbirth and premature birth. This review aims to present the possible role of the NLRP3 inflammasome in the cervical ripening process, emphasizing possible mechanisms of action and regulatory factors.

Methods for the induction of labor: efficacy and safety

This review assessed the efficacy and safety of pharmacologic agents (prostaglandins, oxytocin, mifepristone, hyaluronidase, and nitric oxide donors) and mechanical methods (single- and double-balloon catheters, laminaria, membrane stripping, and amniotomy) and those generally considered under the rubric of complementary medicine (castor oil, nipple stimulation, sexual intercourse, herbal medicine, and acupuncture). A substantial body of published reports, including 2 large network meta-analyses, support the safety and efficacy of misoprostol (PGE1) when used for cervical ripening and labor induction. Misoprostol administered vaginally at doses of 50 μg has the highest probability of achieving vaginal delivery within 24 hours. Regardless of dosing, route, and schedule of administration, when used for cervical ripening and labor induction, prostaglandin E2 seems to have similar efficacy in decreasing cesarean delivery rates. Globally, although oxytocin represents the most widely used pharmacologic agent for labor induction, its effectiveness is highly dependent on parity and cervical status. Oxytocin is more effective than expectant management in inducing labor, and the efficacy of oxytocin is enhanced when combined with amniotomy. However, prostaglandins administered vaginally or intracervically are more effective in inducing labor than oxytocin. A single 200-mg oral tablet of mifepristone seems to represent the lowest effective dose for cervical ripening. The bulk of the literature assessing relaxin suggests this agent has limited benefit when used for this indication. Although intracervical injection of hyaluronidase may cause cervical ripening, the need for intracervical administration has limited the use of this agent. Concerning the vaginal administration of nitric oxide donors, including isosorbide mononitrate, isosorbide, nitroglycerin, and sodium nitroprusside, the higher incidence of side effects with these agents has limited their use. A synthetic hygroscopic cervical dilator has been found to be effective for preinduction cervical ripening. Although a pharmacologic agent may be administered after the use of the synthetic hygroscopic dilator, in an attempt to reduce the interval to vaginal delivery, concomitant use of mechanical and pharmacologic methods is being explored. Combining the use of a single-balloon catheter with dinoprostone, misoprostol, or oxytocin enhances the efficacy of these pharmacologic agents in cervical ripening and labor induction. The efficacy of single- and double-balloon catheters in cervical ripening and labor induction seems similar. To date, the combination of misoprostol with an intracervical catheter seems to be the best approach when balancing delivery times with safety. Although complementary methods are occasionally used by patients, given the lack of data documenting their efficacy and safety, these methods are rarely used in hospital settings.

Clinical chorioamnionitis at term is characterized by changes in the plasma concentration of CHCHD2/MNRR1, a mitochondrial protein

OBJECTIVE

Mitochondrial dysfunction was observed in acute systemic inflammatory conditions such as sepsis and might be involved in sepsis-induced multi-organ failure. Coiled-Coil-Helix-Coiled-Coil-Helix Domain Containing 2 (CHCHD2), also known as Mitochondrial Nuclear Retrograde Regulator 1 (MNRR1), a bi-organellar protein located in the mitochondria and the nucleus, is implicated in cell respiration, survival, and response to tissue hypoxia. Recently, the reduction of the cellular CHCHD2/MNRR1 protein, as part of mitochondrial dysfunction, has been shown to play a role in the amplification of inflammatory cytokines in a murine model of lipopolysaccharide-induced systemic inflammation. The aim of this study was to determine whether the plasma concentration of CHCHD2/MNRR1 changed during human normal pregnancy, spontaneous labor at term, and clinical chorioamnionitis at term.

METHODS

We conducted a cross-sectional study that included the following groups: 1) non-pregnant women (n = 17); 2) normal pregnant women at various gestational ages from the first trimester until term (n = 110); 3) women at term with spontaneous labor (n = 50); and 4) women with clinical chorioamnionitis at term in labor (n = 25). Plasma concentrations of CHCHD2/MNRR1 were assessed by an enzyme-linked immunosorbent assay.

RESULTS

1) Pregnant women at term in labor with clinical chorioamnionitis had a significantly higher plasma CHCHD2/MNRR1 concentration than those in labor without chorioamnionitis (p = .003); 2) CHCHD2/MNRR1 is present in the plasma of healthy non-pregnant and normal pregnant women without significant differences in its plasma concentrations between the two groups; 3) there was no correlation between maternal plasma CHCHD2/MNRR1 concentration and gestational age at venipuncture; and 4) plasma CHCHD2/MNRR1 concentration was not significantly different in women at term in spontaneous labor compared to those not in labor.

CONCLUSIONS

CHCHD2/MNRR1 is physiologically present in the plasma of healthy non-pregnant and normal pregnant women, and its concentration does not change with gestational age and parturition at term. However, plasma CHCHD2/MNRR1 is elevated in women at term with clinical chorioamnionitis. CHCHD2/MNRR1, a novel bi-organellar protein located in the mitochondria and the nucleus, is released into maternal plasma during systemic inflammation.

Chorioamnionitis: An Update on Diagnostic Evaluation

Chorioamnionitis remains a major cause of preterm birth and maternal and neonatal morbidity. We reviewed the current evidence for the diagnostic tests of chorioamnionitis and how this relates to clinical practice today. A comprehensive literature search and review was conducted on chorioamnionitis and intra-uterine inflammation. Data from randomized control trials and systematic reviews were prioritized. This review highlights that sterile inflammation plays an important role in chorioamnionitis and that the current tests for chorioamnionitis including clinical criteria, maternal plasma and vaginal biomarkers lack diagnostic accuracy. Concerningly, these tests often rely on detecting an inflammatory response after damage has occurred to the fetus. Care should be taken when interpreting current investigations for the diagnosis of chorioamnionitis and how they guide obstetric/neonatal management. There is an urgent need for further validation of current diagnostic tests and the development of novel, accurate, minimally invasive tests that detect subclinical intra-uterine inflammation.

The amniotic fluid proteome changes with term labor and informs biomarker discovery in maternal plasma

The intra-uterine components of labor, namely, myometrial contractility, cervical ripening, and decidua/membrane activation, have been extensively characterized and involve a local pro-inflammatory milieu of cellular and soluble immune mediators. Targeted profiling has demonstrated that such processes extend to the intra-amniotic space, yet unbiased analyses of the proteome of human amniotic fluid during labor are lacking. Herein, we utilized an aptamer-based platform to characterize 1,310 amniotic fluid proteins and found that the proteome undergoes substantial changes with term labor (251 proteins with differential abundance, q < 0.1, and fold change > 1.25). Proteins with increased abundance in labor are enriched for immune and inflammatory processes, consistent with prior reports of labor-associated changes in the intra-uterine space. By integrating the amniotic fluid proteome with previously generated placental-derived single-cell RNA-seq data, we demonstrated the labor-driven upregulation of signatures corresponding to stromal-3 and decidual cells. We also determined that changes in amniotic fluid protein abundance are reflected in the maternal plasma proteome. Collectively, these findings provide novel insights into the amniotic fluid proteome in term labor and support its potential use as a source of biomarkers to distinguish between true and false labor by using maternal blood samples.

Inflammatory Changes and Composition of Collagen during Cervical Ripening in Cows

Dystocia and stillbirths in cows pose a high risk of loss of both dams and fetuses, thereby resulting in high economic losses. One of the causes of these problems is birth canal abnormalities. Thus, to prevent these occurrences, it is necessary to understand the mechanisms underlying cervical ripening. Although physiological inflammatory responses and changes in collagen composition have been reported in humans and mice, related information is scarce for cows. We observed inflammatory changes and changes in the collagen composition in the cervix from late pregnancy to parturition to clarify some of the physiological changes associated with cervical ripening during normal calving in cows. Cervical mucus and tissue samples were collected from 41 Japanese Black cows at 200, 230, and 260 days of gestation and at 7-day intervals thereafter until parturition. The percentage of polymorphonuclear neutrophils (PMN%) in the mucus was calculated, and interleukin (IL)-8 concentration was determined by enzyme-linked immunosorbent assay. Blood samples were collected from the jugular vein, and leukocyte counts were determined. Picrosirius red-stained cervical tissue specimens were observed under a polarizing microscope, and the percentage of type I and type III collagen areas in the cervical tissue were calculated. The PMN% in cervical mucus was lowest at 200 days gestation (12−13 weeks before delivery), significantly increased 5 weeks before (21.7 ± 0.04), and was highest 1 week before calving (50.9 ± 0.04). IL-8 levels were increased at 295 days compared with those at 200 days of pregnancy (p < 0.05). No significant changes were observed in the white blood cell counts. The percentage of type I collagen in the cervical tissue reached a maximum (91.4 ± 0.02%) on day 200, significantly decreased after 274 days (3 weeks before calving), and continued to decrease thereafter until the week of parturition. There was no significant change in type III collagen levels. The results suggest that cervical ripening progresses when PMNs begin to infiltrate the cervix at around 260 days of gestation (5−4 weeks before parturition), IL-8, which increases at the end of pregnancy, mobilizes PMNs, and enhances inflammation, and that type I collagen changes are useful as an indicator of cervical ripening.

Study protocol to quantify the genetic architecture of sonographic cervical length and its relationship to spontaneous preterm birth

INTRODUCTION

A short cervix (cervical length <25 mm) in the midtrimester (18-24 weeks) of pregnancy is a powerful predictor of spontaneous preterm delivery. Although the biological mechanisms of cervical change during pregnancy have been the subject of extensive investigation, little is known about whether genes influence the length of the cervix, or the extent to which genetic factors contribute to premature cervical shortening. Defining the genetic architecture of cervical length is foundational to understanding the aetiology of a short cervix and its contribution to an increased risk of spontaneous preterm delivery.

METHODS/ANALYSIS

The proposed study is designed to characterise the genetic architecture of cervical length and its genetic relationship to gestational age at delivery in a large cohort of Black/African American women, who are at an increased risk of developing a short cervix and delivering preterm. Repeated measurements of cervical length will be modelled as a longitudinal growth curve, with parameters estimating the initial length of the cervix at the beginning of pregnancy, and its rate of change over time. Genome-wide complex trait analysis methods will be used to estimate the heritability of cervical length growth parameters and their bivariate genetic correlation with gestational age at delivery. Polygenic risk profiling will assess maternal genetic risk for developing a short cervix and subsequently delivering preterm and evaluate the role of cervical length in mediating the relationship between maternal genetic variation and gestational age at delivery.

ETHICS/DISSEMINATION

The proposed analyses will be conducted using deidentified data from participants in an IRB-approved study of longitudinal cervical length who provided blood samples and written informed consent for their use in future genetic research. These analyses are preregistered with the Center for Open Science using the AsPredicted format and the results and genomic summary statistics will be published in a peer-reviewed journal.

Microbial-driven preterm labour involves crosstalk between the innate and adaptive immune response

There has been a surge in studies implicating a role of vaginal microbiota in spontaneous preterm birth (sPTB), but most are associative without mechanistic insight. Here we show a comprehensive approach to understand the causative factors of preterm birth, based on the integration of longitudinal vaginal microbiota and cervicovaginal fluid (CVF) immunophenotype data collected from 133 women at high-risk of sPTB. We show that vaginal depletion of Lactobacillus species and high bacterial diversity leads to increased mannose binding lectin (MBL), IgM, IgG, C3b, C5, IL-8, IL-6 and IL-1β and to increased risk of sPTB. Cervical shortening, which often precedes preterm birth, is associated with Lactobacillus iners and elevated levels of IgM, C3b, C5, C5a and IL-6. These data demonstrate a role for the complement system in microbial-driven sPTB and provide a scientific rationale for the development of live biotherapeutics and complement therapeutics to prevent sPTB.

Gaining mechanistic insight into the microbiological and immunological factors that are associated with spontaneous preterm birth is important for the development of prevention strategies. Here authors show that the complement system in conjunction with specific vaginal microbial and associated immunological changes are contributing to this condition.

Breaking Down the Barrier: The Role of Cervical Infection and Inflammation in Preterm Birth

Approximately 40% of cases of spontaneous preterm birth (sPTB) are associated with ascending intrauterine infections. The cervix serves as a physical and immunological gatekeeper, preventing the ascent of microorganisms from the vagina to the amniotic cavity. The cervix undergoes remodeling during pregnancy. It remains firm and closed from the start until the late third trimester of pregnancy and then dilates and effaces to accommodate the passage of the fetus during delivery. Remodeling proceeds appropriately and timely to maintain the pregnancy until term delivery. However, risk factors, such as acute and chronic infection and local inflammation in the cervix, may compromise cervical integrity and result in premature remodeling, predisposing to sPTB. Previous clinical studies have established bacterial (i.e., chlamydia, gonorrhea, mycoplasma, etc.) and viral infections (i.e., herpesviruses and human papillomaviruses) as risk factors of PTB. However, the exact mechanism leading to PTB is still unknown. This review focuses on: (1) the epidemiology of cervical infections in pregnant patients; (2) cellular mechanisms that may explain the association of cervical infections to premature cervical ripening and PTB; (3) endogenous defense mechanisms of the cervix that protect the uterine cavity from infection and inflammation; and (4) potential inflammatory biomarkers associated with cervical infection that can serve as prognostic markers for premature cervical ripening and PTB. This review will provide mechanistic insights on cervical functions to assist in managing cervical infections during pregnancy.

Transcriptome changes in maternal peripheral blood during term parturition mimic perturbations preceding spontaneous Preterm birth†

The complex physiologic process of parturition includes the onset of labor, which requires the orchestrated stimulation of a common pathway involving uterine contractility, cervical ripening, and chorioamniotic membrane activation. However, the labor-specific processes taking place in these tissues have limited use as predictive biomarkers unless they can be probed in non-invasive samples, such as the peripheral blood. Herein, we utilized a transcriptomic dataset to assess labor-specific changes in the peripheral blood of women who delivered at term. We identified a set of genes that were differentially expressed with labor and enriched for immunological processes, and these gene expression changes were strongly correlated with results from prior studies, providing in silico validation of our findings. We then identified significant correlations between labor-specific transcriptomic changes in the maternal circulation and those reported in the chorioamniotic membranes, myometrium, and cervix of women at term, demonstrating that tissue-specific labor signatures are partly mirrored in the peripheral blood. Last, we demonstrated a significant overlap between the peripheral blood transcriptomic changes in term parturition and those observed in asymptomatic women prior to the diagnosis of preterm prelabor rupture of membranes who delivered preterm. Collectively, we provide evidence that the normal process of labor at term is characterized by a unique immunological expression signature, which may serve as a useful tool for assessing labor status and potentially identifying women at risk for preterm birth.

Macrophages exert homeostatic actions in pregnancy to protect against preterm birth and fetal inflammatory injury

Macrophages are commonly thought to contribute to the pathophysiology of preterm labor by amplifying inflammation — but a protective role has not previously been considered to our knowledge. We hypothesized that given their antiinflammatory capability in early pregnancy, macrophages exert essential roles in maintenance of late gestation and that insufficient macrophages may predispose individuals to spontaneous preterm labor and adverse neonatal outcomes. Here, we showed that women with spontaneous preterm birth had reduced CD209⁺CD206⁺ expression in alternatively activated CD45⁺CD14⁺ICAM3^– macrophages and increased TNF expression in proinflammatory CD45⁺CD14⁺CD80⁺HLA-DR⁺ macrophages in the uterine decidua at the materno-fetal interface. In Cd11b^DTR/DTR mice, depletion of maternal CD11b⁺ myeloid cells caused preterm birth, neonatal death, and postnatal growth impairment, accompanied by uterine cytokine and leukocyte changes indicative of a proinflammatory response, while adoptive transfer of WT macrophages prevented preterm birth and partially rescued neonatal loss. In a model of intra-amniotic inflammation–induced preterm birth, macrophages polarized in vitro to an M2 phenotype showed superior capacity over nonpolarized macrophages to reduce uterine and fetal inflammation, prevent preterm birth, and improve neonatal survival. We conclude that macrophages exert a critical homeostatic regulatory role in late gestation and are implicated as a determinant of susceptibility to spontaneous preterm birth and fetal inflammatory injury.

Human β-defensin-3 participates in intra-amniotic host defense in women with labor at term, spontaneous preterm labor and intact membranes, and preterm prelabor rupture of membranes

Objective: Human β-defensin-3 (HBD-3) has a broad spectrum of antimicrobial activity, and activity and, therefore, plays a central role in host defense mechanisms against infection. Herein, we determined whether HBD-3 was a physiological constituent of amniotic fluid during midtrimester and at term and whether the concentration of this defensin was increased in amniotic fluid of women with spontaneous preterm labor and intact membranes and those with preterm prelabor rupture of membranes (pPROM) with intra-amniotic inflammation or intra-amniotic infection.Methods: Amniotic fluid was collected from 219 women in the following groups: (1) midtrimester who delivered at term (n = 35); (2) with or without spontaneous labor at term (n = 50); (3) spontaneous preterm labor with intact membranes who delivered at term (n = 29); (4) spontaneous preterm labor with intact membranes who delivered preterm with or without intra-amniotic inflammation or intra-amniotic infection (n = 69); and (5) pPROM with or without intra-amniotic infection (n = 36). Amniotic fluid HBD-3 concentrations were determined using a sensitive and specific ELISA kit.Results: (1) HBD-3 is a physiological constituent of amniotic fluid; (2) the amniotic fluid concentration of HBD-3 did not change with gestational age (midtrimester versus term not in labor); (3) amniotic fluid concentrations of HBD-3 were higher in women with spontaneous labor at term than in those without labor; (4) in the absence of intra-amniotic inflammation, amniotic fluid concentrations of HBD-3 were similar between women with spontaneous preterm labor who delivered preterm and those who delivered at term; (5) among patients with spontaneous preterm labor who delivered preterm, amniotic fluid concentrations of HBD-3 were greater in women with intra-amniotic infection than in those without this clinical condition; (6) among patients with spontaneous preterm labor, amniotic fluid concentrations of HBD-3 were higher in women with intra-amniotic inflammation or intra-amniotic infection who delivered preterm than in those without these clinical conditions who delivered at term; and (7) women with pPROM and intra-amniotic infection had higher median amniotic fluid concentrations of HBD-3 than those without this clinical condition.Conclusion: Human β-defensin-3 is a physiological constituent of amniotic fluid and increases during the process of labor at term. Amniotic fluid concentrations of HBD-3 were increased in women with spontaneous preterm labor with intact membranes or pPROM with intra-amniotic inflammation or intra-amniotic infection, indicating that this defensin participates in the host defense mechanisms in the amniotic cavity against microorganisms or danger signals. These findings provide insight into the soluble host defense mechanisms against intra-amniotic inflammation and intra-amniotic infection.

Cervicovaginal natural antimicrobial expression in pregnancy and association with spontaneous preterm birth

There is much interest in the role of innate immune system proteins (antimicrobial peptides) in the inflammatory process associated with spontaneous preterm birth (sPTB). After promising pilot work, we aimed to validate the association between the antimicrobial peptides/proteins elafin and cathelicidin and sPTB. An observational cohort study of 405 women at high-risk, and 214 women at low-risk of sPTB. Protein concentrations of elafin and cathelicidin, and the enzyme human neutrophil elastase (HNE) were measured in over 1,000 cervicovaginal fluid (CVF) samples (10 to 24 weeks’ gestation). Adjusted CVF cathelicidin and HNE concentrations (but not elafin) were raised in high-risk women who developed cervical shortening and who delivered prematurely and were predictive of sPTB < 37 weeks, with an area under the curve (AUC) of 0.75 (95% CI 0.68 to 0.81) for cathelicidin concentration at 14 to 15⁺⁶ weeks. Elafin concentrations were affected by gestation, body mass index and smoking. CVF elafin in early pregnancy was modestly predictive of sPTB < 34 weeks (AUC 0.63, 0.56–0.70). Alterations in innate immune response proteins in early pregnancy are predictive of sPTB. Further investigation is warranted to understand the drivers for this, and their potential to contribute towards clinically useful prediction techniques.

The effects of advanced maternal age on T-cell subsets at the maternal-fetal interface prior to term labor and in the offspring: a mouse study

Women who conceive at 35 years of age or older, commonly known as advanced maternal age, have a higher risk of facing parturition complications and their children have an increased risk of developing diseases later in life. However, the immunological mechanisms underlying these pathological processes have yet to be established. To fill this gap in knowledge, using a murine model and immunophenotyping, we determined the effect of advanced maternal age on the main cellular branch of adaptive immunity, T cells, at the maternal-fetal interface and in the offspring. We report that advanced maternal age impaired the process of labor at term, inducing dystocia and delaying the timing of delivery. Advanced maternal age diminished the number of specific proinflammatory T-cell subsets [T helper type 1 (Th1): CD4⁺ IFN-γ⁺ , CD8⁺ IFN-γ⁺ and Th9: CD4⁺ IL-9⁺ ], as well as CD4⁺ regulatory T cells (CD4⁺ CD25⁺ FoxP3⁺ T cells), at the maternal-fetal interface prior to term labor. Advanced maternal age also altered fetal growth and survival of the offspring in early life. In addition, infants born to advanced-age mothers had alterations in the T-cell repertoire but not in CD71⁺ erythroid cells (CD3^- CD71⁺ TER119⁺ cells). This study provides insight into the immune alterations observed at the maternal-fetal interface of advanced-age mothers and their offspring.

The oxytocin-prostaglandins pathways in the horse (Equus caballus) placenta during pregnancy, physiological parturition, and parturition with fetal membrane retention

Despite their importance in mammalian reproduction, substances in the oxytocin-prostaglandins pathways have not been investigated in the horse placenta during most of pregnancy and parturition. Therefore, we quantified placental content of oxytocin (OXT), oxytocin receptor (OXTR), and prostaglandin E2 and F2 alpha during days 90-240 of pregnancy (PREG), physiological parturition (PHYS), and parturition with fetal membrane retention (FMR) in heavy draft horses (PREG = 13, PHYS = 11, FMR = 10). We also quantified OXTR and prostaglandin endoperoxide synthase-2 (PTGS2) mRNA expression and determined the immunolocalization of OXT, OXTR, and PTGS2. For relative quantification of OXT and OXTR, we used western blotting with densitometry. To quantify the prostaglandins, we used enzyme immunoassays. For relative quantification of OXTR and PTGS2, we used RT-qPCR. For immunolocalization of OXT, OXTR, and PTGS2, we used immunohistochemistry. We found that OXT was present in cells of the allantochorion and endometrium in all groups. PTGS2 expression in the allantochorion was 14.7-fold lower in FMR than in PHYS (p = 0.007). These results suggest that OXT is synthesized in the horse placenta. As PTGS2 synthesis is induced by inflammation, they also suggest that FMR in heavy draft horses may be associated with dysregulation of inflammatory processes.

Immunobiology of Cervix Ripening

The cervix is the essential gatekeeper for birth. Incomplete cervix remodeling contributes to problems with delivery at or post-term while preterm birth is a major factor in perinatal morbidity and mortality in newborns. Lack of cervix biopsies from women during the period preceding term or preterm birth have led to use of rodent models to advanced understanding of the mechanism for prepartum cervix remodeling. The critical transition from a soft cervix to a compliant prepartum lower uterine segment has only recently been recognized to occur in various mammalian species when progesterone in circulation is at or near the peak of pregnancy in preparation for birth. In rodents, characterization of ripening resembles an inflammatory process with a temporal coincidence of decreased density of cell nuclei, decline in cross-linked extracellular collagen, and increased presence of macrophages in the cervix. Although a role for inflammation in parturition and cervix remodeling is not a new concept, a comprehensive examination of literature in this review reveals that many conclusions are drawn from comparisons before and after ripening has occurred, not during the process. The present review focuses on essential phenotypes and functions of resident myeloid and possibly other immune cells to bridge the gap with evidence that specific biomarkers may assess the progress of ripening both at term and with preterm birth. Moreover, use of endpoints to determine the effectiveness of various therapeutic approaches to forestall remodeling and reduce risks for preterm birth, or facilitate ripening to promote parturition will improve the postpartum well-being of mothers and newborns.

Cell-Free Fetal DNA Increases Prior to Labor at Term and in a Subset of Preterm Births

Cell-free fetal DNA in the maternal circulation has been associated with the onset of labor at term. Moreover, clinical studies have suggested that cell-free fetal DNA has value to predict pregnancy complications such as spontaneous preterm labor leading to preterm birth. However, a mechanistic link between cell-free fetal DNA and preterm labor and birth has not been established. Herein, using an allogeneic mouse model in which a paternal green fluorescent protein (GFP) can be tracked in the fetuses, we established that cell-free fetal DNA (Egfp) concentrations were higher in late gestation compared to mid-pregnancy and were maintained at increased levels during the onset of labor at term, followed by a rapid decrease after birth. A positive correlation between cell-free fetal DNA concentrations and the number of GFP-positive pups was also observed. The increase in cell-free fetal DNA concentrations prior to labor at term was not linked to a surge in any specific cytokine/chemokine; yet, specific chemokines (i.e., CCL2, CCL7, and CXCL2) increased as gestation progressed and maintained elevated levels in the postpartum period. In addition, cell-free fetal DNA concentrations increased prior to systemic inflammation-induced preterm birth, which was associated with a strong cytokine response in the maternal circulation. However, cell-free fetal DNA concentrations were not increased prior to intra-amniotic inflammation-induced preterm birth, but in this model, a mild inflammatory response was observed in the maternal circulation. Collectively, these findings suggest that an elevation in cell-free fetal DNA concentrations in the maternal circulation precedes the physiological process of labor at term and the pathological process of preterm labor linked with systemic inflammation, but not that associated with intra-amniotic inflammation.

Gasdermin D: in vivo evidence of pyroptosis in spontaneous labor at term

Objective: Pyroptosis is an inflammatory form of programmed cell death that is mediated by the activation of the inflammasome and depends on the pore-forming function of gasdermin D. Therefore, the detection of gasdermin D represents in vivo evidence of pyroptosis. We recently showed that there is intra-amniotic inflammasome activation in spontaneous labor at term; however, evidence of pyroptosis is lacking. The objectives of this study were to investigate (1) whether gasdermin D is detectable in the amniotic fluid of women who delivered at term; (2) whether amniotic fluid gasdermin D concentrations are associated with the process of spontaneous labor at term; and (3) whether gasdermin D is expressed in the chorioamniotic membranes from these patients.Methods: This retrospective cross-sectional study included amniotic fluid samples from 41 women who underwent spontaneous labor at term (n = 17) or delivered at term without labor (n = 24). As a readout of pyroptosis, gasdermin D was determined in amniotic fluid samples using a specific and sensitive ELISA kit. The 90th percentile of amniotic fluid gasdermin D concentrations was calculated among women without spontaneous labor at term (reference group). The association between high amniotic fluid gasdermin D concentrations (≥90th percentile in the reference group) and spontaneous labor at term was tested using the Fisher's exact test. A p value <.05 was considered significant. Multiplex immunofluorescence staining and phenoptics (multispectral imaging) were performed to determine gasdermin D expression in the chorioamniotic membranes and to colocalize this protein with the inflammasome-related molecules caspase-1 and interleukin-1β.Results: (1) Gasdermin D is present in the amniotic fluid of women who delivered at term; (2) the 90th percentile of amniotic fluid gasdermin D concentrations in women who delivered at term without spontaneous labor was 3.4 ng/mL; (3) the proportion of women with amniotic fluid gasdermin D concentrations above the threshold was higher in those who underwent term labor than in those who delivered at term without labor; (4) amniotic fluid concentrations of gasdermin D > 3.4 ng/mL were significantly associated with the presence of spontaneous labor in women who delivered at term (odds ratio 6.0, p-value .048); and (5) the protein expression of gasdermin D is increased in the chorioamniotic membranes of women who underwent spontaneous labor at term and is colocalized with caspase-1 and IL-1β.Conclusions: Gasdermin D is increased in the amniotic fluid and chorioamniotic membranes of women who underwent spontaneous labor at term compared to those without labor. These data provide evidence implicating pyroptosis in the mechanisms that lead to the sterile inflammatory process of term parturition.

Antibiotic treatment for patients with amniotic fluid "sludge" to prevent spontaneous preterm birth: A historically controlled observational study

INTRODUCTION

Amniotic fluid "sludge" has been associated with an increased rate of spontaneous preterm delivery before 35 weeks, a higher frequency of clinical and histologic chorioamnionitis in a high-risk population. Only one study evaluating the use of antibiotics in the presence of amniotic fluid "sludge" showed reduced rates of spontaneous preterm birth at <34 weeks. The objective of this study was to evaluate routine antibiotic treatment in the presence of amniotic fluid "sludge" for prevention of preterm delivery.

MATERIAL AND METHODS

A historically controlled observational study was performed between October 2010 and January 2015, including a total of 86 pregnant women with singleton pregnancies and the presence of amniotic fluid "sludge" at ultrasound. Women admitted from October 2010 to September 2012 received no treatment with antibiotics, whereas those admitted from October 2012 to January 2015, received routinely clindamycin and first-generation cephalosporin. The groups were compared considering the incidence of spontaneous preterm delivery. The effect of antimicrobials was also compared in the subgroup of women at high risk for spontaneous preterm birth (ie, cervical length ≤25 mm, history of spontaneous preterm birth, previous spontaneous loss in the second trimester, Mullerian malformations or cervical conization).

RESULTS

Antibiotic therapy reduced the incidence of spontaneous preterm birth at <34 weeks (13.2% vs 38.5%, P = 0.047) in women at high-risk for preterm birth, with an odds ratio of 0.24 (95% confidence interval [CI] 0.06-0.99). Birthweight was significantly different between the study groups (2961 ± 705 vs. 2554 ± 819 g, respectively; P = 0.028), with no statistical significance for others variables.

CONCLUSIONS

This study suggests that antibiotic treatment in high-risk pregnant women with amniotic fluid "sludge" can be effective in the reduction of the frequency of spontaneous preterm delivery and can increase the birthweight.

Neutrophil elastase in cervical fluid in women with short cervical length

OBJECTIVE

The aim of the study was to determine the relationships between short cervical length (CL) and levels of cervical fluid neutrophil elastase (NE), secretory leukocyte protease inhibitor (SLPI), and interleukin 8 (IL-8) in the second trimester of pregnancy of women who underwent ultrasound-indicated cervical cerclage.

MATERIALS AND METHODS

CL of <25 mm or cervical funneling were included in the short CL group (n = 26) and the normal CL group (n = 22) included women who had CL of ≥25 mm and had no cervical funneling in women between 17 + 0 and 24 + 6 weeks of gestation. Levels of NE, SLPI, and IL-8 were measured by using enzyme-linked immunosorbent assay kits. Mann-Whitney U tests and Spearman's correlation analysis were used for statistical analyses.

RESULTS

Compared with the normal CL group, the short CL group had significantly higher median NE levels (P < 0.001) and higher, though not significant, median IL-8 levels by approximately three times (2107.0 vs. 798.3 pg/mL, P = 0.132). The median SLPI levels in cervical fluid was similar between the two groups (107.6 vs. 103.2 ng/mL, P = 0.499). Short CL had a significant correlations with cervical fluid NE levels (r = -0.475, P = 0.001).

CONCLUSION

Increased cervical fluid NE associated with cervical shortening in second trimester of pregnancy, whereas cervical fluid SLPI had constant levels.

A diet enriched in longer chain omega-3 fatty acids reduced placental inflammatory cytokines and improved fetal sustainability of C57BL/6 mice

Omega (n)-3 polyunsaturated fatty acids (PUFA) are important regulators of inflammatory response that may impact pregnancy outcome. The effects of breeding chow diets containing n-3 PUFA from either fish oil (FO) or soybean oil (SO) were investigated on tissue fatty acid composition, inflammatory cytokines and pregnancy outcome. Female C57BL/6 mice (7 weeks old) were fed FO or SO diets for 2 weeks before mating and throughout pregnancy. Animals were sacrificed before and during pregnancy at day 6.5, 12.5 and 18.5. The FO diet increased the incorporation of n-3 PUFA in placenta, with a concomitant decrease in the concentration of pro-inflammatory cytokines. The FO diet increased the mRNA expression of placental specific PUFA transporter, which coincided with accretion of n-3 PUFA in fetal brain. Sites of fetal resorption were noticeable in the SO group but not in the FO group. N-3 PUFA may improve fetal sustainability via altering cytokine levels.

In vivo evidence of inflammasome activation during spontaneous labor at term

OBJECTIVE

Upon inflammasome activation, the adaptor protein of the inflammasome ASC (apoptosis-associated speck-like protein containing a CARD) forms intracellular specks, which can be released into the extracellular space. The objectives of this study were to investigate whether (1) extracellular ASC is present in the amniotic fluid of women who delivered at term; (2) amniotic fluid ASC concentrations are greater in women who underwent spontaneous labor at term than in those who delivered at term in the absence of labor; and (3) amniotic epithelial and mesenchymal cells can form intracellular ASC specks in vitro.

METHODS

This retrospective cross-sectional study included amniotic fluid samples from 41 women who delivered at term in the absence of labor (n = 24) or underwent spontaneous labor at term (n = 17). Amniotic epithelial and mesenchymal cells were also isolated from the chorioamniotic membranes obtained from a separate group of women who delivered at term (n = 3), in which ASC speck formation was assessed by confocal microscopy. Monocytes from healthy individuals were used as positive controls for ASC speck formation (n = 3).

RESULTS

(1) The adaptor protein of the inflammasome ASC is detectable in the amniotic fluid of women who delivered at term; (2) amniotic fluid ASC concentration was higher in women who underwent spontaneous labor at term than in those who delivered at term without labor; and (3) amniotic epithelial and mesenchymal cells are capable of forming ASC specks and/or filaments in vitro.

CONCLUSION

Amniotic fluid ASC concentrations are increased in women who undergo spontaneous labor at term. Amniotic epithelial and mesenchymal cells are capable of forming ASC specks, suggesting that these cells are a source of extracellular ASC in the amniotic fluid. These findings provide in vivo evidence that there is inflammasome activation in the amniotic cavity during the physiological process of labor at term.

Fetal death: an extreme manifestation of maternal anti-fetal rejection

OBJECTIVE

The aim of this study was to determine the association between chronic placental inflammation and amniotic fluid (AF) markers of maternal anti-fetal rejection as well as the presence of microorganisms in the AF fluid of patients with fetal death.

STUDY DESIGN

This cohort study included 40 patients with fetal death whose placentas were examined for chronic inflammatory lesions and whose AF chemokine ligand (CXCL)10 and interleukin (IL)-6 concentrations were determined by immunoassays. AF was processed for bacteria, mycoplasmas and viruses using cultivation and molecular microbiologic techniques (i.e. PCR-ESI/MS).

RESULTS

(1) The most prevalent placental findings were maternal vascular underperfusion (63.2%, 24/38), followed by chronic inflammatory lesions (57.9%, 22/38); (2) chronic chorioamnionitis (18/38) was three times more frequent than villitis of unknown etiology (6/38); (3) an elevated AF CXCL10 concentration (above the 95th centile) was present in 60% of the cases, and a receiver operating characteristics (ROC)-derived cut-off of 2.9 ng/mL had a sensitivity of 73% and a specificity of 75% in the identification of chronic placental inflammatory lesions; (4) only five cases had microbial invasion of the amniotic cavity, and the presence of microorganisms did not correlate with chronic placental inflammation.

CONCLUSION

In women with unexplained fetal death, there is an association between elevated AF CXCL10 and chronic placental inflammatory lesions. Therefore, we conclude that a subset of patients with fetal death may have endured a breakdown of maternal-fetal tolerance, which cannot be attributed to microorganisms in the amniotic cavity.

The preterm cervix reveals a transcriptomic signature in the presence of premature prelabor rupture of membranes

BACKGROUND

Premature prelabor rupture of fetal membranes accounts for 30% of all premature births and is associated with detrimental long-term infant outcomes. Premature cervical remodeling, facilitated by matrix metalloproteinases, may trigger rupture at the zone of the fetal membranes overlying the cervix. The similarities and differences underlying cervical remodeling in premature prelabor rupture of fetal membranes and spontaneous preterm labor with intact membranes are unexplored.

OBJECTIVES

We aimed to perform the first transcriptomic assessment of the preterm human cervix to identify differences between premature prelabor rupture of fetal membranes and preterm labor with intact membranes and to compare the enzymatic activities of matrix metalloproteinases-2 and -9 between premature prelabor rupture of fetal membranes and preterm labor with intact membranes.

STUDY DESIGN

Cervical biopsies were collected following preterm labor with intact membranes (n = 6) and premature prelabor rupture of fetal membranes (n = 5). Biopsies were also collected from reference groups at term labor (n = 12) or term not labor (n = 5). The Illumina HT-12 version 4.0 BeadChips microarray was utilized, and a novel network graph approach determined the specificity of changes between premature prelabor rupture of fetal membranes and preterm labor with intact membranes. Quantitative reverse transcription-polymerase chain reaction and Western blotting confirmed the microarray findings. Immunofluorescence was used for localization studies and gelatin zymography to assess matrix metalloproteinase activity.

RESULTS

PML-RARA-regulated adapter molecule 1, FYVE-RhoGEF and PH domain-containing protein 3 and carcinoembryonic antigen-ralated cell adhesion molecule 3 were significantly higher, whereas N-myc downstream regulated gene 2 was lower in the premature prelabor rupture of fetal membranes cervix when compared with the cervix in preterm labor with intact membranes, term labor, and term not labor. PRAM1 and CEACAM3 were localized to immune cells at the cervical stroma and NDRG2 and FGD3 were localized to cervical myofibroblasts. The activity of matrix metalloproteinase-9 was higher (1.22 ± 4.403-fold, P < .05) in the cervix in premature prelabor rupture of fetal membranes compared with preterm labor with intact membranes.

CONCLUSION

We identified 4 novel proteins with a potential role in the regulation of cervical remodeling leading to premature prelabor rupture of fetal membranes. Our findings contribute to the studies dissecting the mechanisms underlying premature prelabor rupture of fetal membranes and inspire further investigations toward the development of premature prelabor rupture of fetal membranes therapeutics.

Novel Toll-like receptor-4 antagonist (+)-naloxone protects mice from inflammation-induced preterm birth

Toll-like receptor 4 (TLR4) activation by bacterial infection, or by sterile inflammatory insult is a primary trigger of spontaneous preterm birth. Here we utilize mouse models to investigate the efficacy of a novel small molecule TLR4 antagonist, (+)-naloxone, the non-opioid isomer of the opioid receptor antagonist (−)-naloxone, in infection-associated preterm birth. Treatment with (+)-naloxone prevented preterm delivery and alleviated fetal demise in utero elicited by i.p. LPS administration in late gestation. A similar effect with protection from preterm birth and perinatal death, and partial correction of reduced birth weight and postnatal mortality, was conferred by (+)-naloxone administration after intrauterine administration of heat-killed E. coli. Local induction by E. coli of inflammatory cytokine genes Il1b, Il6, Tnf and Il10 in fetal membranes was suppressed by (+)-naloxone, and cytokine expression in the placenta, and uterine myometrium and decidua, was also attenuated. These data demonstrate that inhibition of TLR4 signaling with the novel TLR4 antagonist (+)-naloxone can suppress the inflammatory cascade of preterm parturition, to prevent preterm birth and perinatal death. Further studies are warranted to investigate the utility of small molecule inhibition of TLR-driven inflammation as a component of strategies for fetal protection and delaying preterm birth in the clinical setting.

Fetuses Delivered Following Preterm Prelabor Rupture of the Membranes are Capable of Stimulating a Proinflammatory Response in Endothelial Cells

OBJECTIVE

Preterm premature rupture of the membranes (PROM) has been attributed to ascending infection and a choriodecidual inflammatory response (ie, on the maternal side). However, on the fetal side those most at risk of morbidity have a systemic proinflammatory cytokine response. We have recently defined a similar proinflammatory response in pregnancies complicated by vascular disease on the fetal side of the placenta. A factor(s) present in fetal plasma from these pregnancies can stimulate human umbilical vein endothelial cells (HUVECs) to express mRNA for the proinflammatory cytokines, interleukin (IL)-6 and IL-8. The hypothesis of this study was that a similar factor(s) was present in preterm PROM.

METHODS

A standard culture of HUVECs was incubated with fetal plasma, obtained immediately following delivery, from normal pregnancies delivering vaginally at term (n=16) and pregnancies delivering following preterm PROM (n=19). Expression of mRNA for IL-6 and IL-8 was assessed by reverse transcription polymerase chain reaction (RT-PCR) and standardized to GAPDH mRNA expression.

RESULTS

Endothelial cell expression of IL-6 mRNA (median [25-75th centile] 0.295 [0.252-0.507] vs term vaginal delivery 0.208 [0.151-0.307]; P=.009) was enhanced in response to the fetal plasma from PROM cases compared to pregnancies delivering vaginally at term. In contrast, mRNA expression of IL-8 (median [25-75th centile] preterm PROM 0.41 [0.21-0.78] vs term vaginal delivery 0.49 [0.16-0.68]; P=.46) was not different in the two groups.

CONCLUSIONS

We have demonstrated that in fetuses delivered following preterm PROM there is a factor(s) capable of stimulating a local endothelial cell proinflammatory cytokine (IL-6) response. This factor(s) that we have demonstrated may be responsible for the increased cytokine production seen in fetuses with the fetal inflammatory response syndrome.

Characterization of Vascular Endothelial Growth Factor (VEGF) in the Uterine Cervix over Pregnancy: Effects of Denervation and Implications for Cervical Ripening

Bilateral neurectomy of the pelvic nerve (BLPN) that carries uterine cervix-related sensory nerves induces dystocia, and administration of its vasoactive neuropeptides induces changes in the cervical microvasculature, resembling those that occur in the ripening cervix. This study was designed to test the hypothesis that (a) the cervix of pregnant rats expresses vascular endothelial growth factor (VEGF) and components of the angiogenic signaling pathway [VEGF receptors (Flt-1, KDR), activity of protein kinase B, Akt (phosphorylated Akt), and endothelial nitric oxide synthase (eNOS)] and von Willebrand Factor (vWF) and that these molecules undergo changes with pregnancy, and (b) bilateral pelvic neurectomy (BLPN) alters levels of VEGF concentration in the cervix. Using RT-PCR and sequencing, two VEGF isoforms, 120 and 164, were identified in the rat cervix. VEGF, VEGF receptor-1 (Flt-1), eNOS, and vWF immunoreactivities (ir) were localized in the microvasculature of cervical stroma. Their protein levels increased during pregnancy but decreased to control levels by 2 days postpartum. VEGF receptor-2 (KDR)-ir was confined to the epithelium of the endocervix. BLPN downregulated levels of VEGF by a third. Therefore, the components of the angiogenic signaling pathway are expressed in the cervix and change over pregnancy. Furthermore, angiogenic and sensory neuronal factors may be important in regulating the dynamic microvasculature in the ripening cervix and may subsequently play a role in cervical ripening and the birth process.

The Role of Sensory Neurons in Cervical Ripening: Effects of Estrogen and Neuropeptides

Central nervous system nuclei and circuits, such as the medial preoptic, ventromedial and paraventricular nuclei of the hypothalamus, play important roles in reproduction and parturition, and are influenced by estrogen. Peripheral autonomic and sensory neurons also play important roles in pregnancy and parturition. Moreover, the steroid hormone estrogen acts directly, not only on the reproductive tract organs (uterus and cervix), but also on the central and peripheral nerves by regulating expression of various neuronal genes. The peripheral primary afferent neurons innervating the uterine cervix relay mechanical and biochemical sensory information induced by local cervical events and by passage of fetuses, to the spinal cord and supraspinal centers. Consequently, the birth process in mammals is influenced by the combined action of neurons and hormones. Peripheral sensory stimuli, induced physiologically by fetal expulsion or mechanically by vaginocervical stimulation, alter behavior, as well as autonomic and neuroendocrine systems. Recent evidence indicates that primary afferent neurons innervating the cervix, in addition to their sensory effects, likely exert local “efferent” actions on the ripening cervix near term. These efferent effects may involve estrogen-regulated production of such neuropeptides as substance P and calcitonin gene-related peptide in lumbosacral dorsal root ganglia, and their release in the cervix. Collectively, these findings suggest an interrelationship among estrogen, cervix-related sensory neurons, and local cervical events near term.

Progesterone Receptor-Mediated Actions Regulate Remodeling of the Cervix in Preparation for Preterm Parturition

This study determined whether a progesterone (P) receptor (PR)-mediated mechanism regulates morphological characteristics associated with prepartum cervix remodeling at term and with preterm birth. With focus on the transition from a soft to ripe cervix, the cervix stroma of untreated controls had reduced cell nuclei density/area and less organized extracellular collagen, while the density of macrophages/area, but not neutrophils, increased just 2 days before birth (day 17 vs day 15 or 16.5 postbreeding). Preterm birth was induced within 24 hours of treatment on day 16 postbreeding with PR antagonist or ovariectomy (Ovx). Pure or mixed PR antagonists increased the density of macrophages in the cervix within 8 hours (day 16.5 postbreeding), in advance of preterm birth. However, neither PR antagonists nor P withdrawal after Ovx affected the densities of cell nuclei and neutrophils or extracellular collagen compared to the same day controls-an indication that the cervix was sufficiently remodeled for birth to occur. To block the effect of systemic P withdrawal, Ovx pregnant mice were given a PR agonist, either pure or mixed. These treatments forestalled preterm birth and prevented further morphological remodeling of the cervix. The resulting increase in macrophage density in cervix stroma following Ovx was only blocked by a pure PR agonist. These findings support the hypothesis that inflammatory processes in the prepartum cervix that include residency of macrophages, cellular hypertrophy, and extracellular collagen structure are regulated by genomic actions of PR in a final common mechanism both at term and with induced preterm birth.

A Role for the Inflammasome in Spontaneous Labor at Term

PROBLEM

Inflammasomes are signaling platforms that, upon sensing pathogens and sterile stressors, mediate the release of mature forms of interleukin (IL)-1β and IL-18. The aims of this study were to determine (i) the expression of major inflammasome components in the chorioamniotic membranes in spontaneous labor at term, (ii) whether there are changes in the inflammasome components associated with the activation of caspase-1 and caspase-4, and (iii) whether these events are associated with the release of the mature forms of IL-1β and IL-18.

METHOD OF STUDY

Chorioamniotic membranes were collected from women at term with and without spontaneous labor. mRNA abundance and protein concentrations of inflammasome components, nucleotide-binding oligomerization domain-containing (NOD)1 and NOD2 proteins, caspase-1, caspase-4, IL-1β, and IL-18 were quantified by qRT-PCR (n = 28-29 each), ELISA (n = 10 each) or immunoblotting (n = 8 each), and immunohistochemistry (n = 10 each). Active caspase-1 and caspase-4, as well as mature IL-18, were determined by immunoblotting (n = 4 each), and pro- and mature forms of IL-1β were determined by ELISA (n = 4-7 each).

RESULTS

Inflammasome components and NOD proteins were expressed in the chorioamniotic membranes obtained from women at term. The chorioamniotic membranes from women who underwent labor had (i) higher concentrations of NLRP3 (NOD-like receptor family, pyrin domain-containing protein 3) and NOD1 protein, (ii) greater immunoreactivity for caspase-1 and caspase-4, (iii) a greater quantity of the active form of caspase-1 (p20), and (iv) higher mRNA abundance and protein concentrations of pro- and mature IL-1β. However, mRNA abundance and protein concentrations of the mature form of IL-18 were not increased in tissues from women who underwent labor at term.

CONCLUSIONS

Spontaneous labor at term is characterized by the expression of inflammasome components, which may participate in the activation of caspase-1 and lead to the cleavage and release of mature IL-1β by the chorioamniotic membranes. These results support the participation of the inflammasome in the mechanisms responsible for spontaneous parturition at term.

Effects of combined progesterone and 17β-estradiol treatment on the transcriptome of cultured human myometrial smooth muscle cells

A transcriptomic analysis of cultured human uterine smooth muscle cells (hUtSMCs) was performed to examine gene expression profiles in smooth muscle in an environment containing the two major steroid hormones that regulate the human myometrium in physiological states associated with estrous, pregnancy, labor, and pathophysiological states such as leiomyoma and endometrial cancer. hUtSMCs were treated with progesterone (P4) and 17β-estradiol (E2) individually and in combination, in the presence and absence of RU486 (mifepristone). Transcription of many genes was modulated in the presence of P4 or E2 alone, but almost six times more genes were transcriptionally modulated in the presence of the P4/E2 hormone combination. In total 796 annotated genes were significantly differentially expressed in the presence of both P4 and E2 relative to their expression in untreated cells. Functional withdrawal of P4 by addition of RU486 effectively reversed almost all transcriptional changes caused by P4/E2 treatment. Gene ontology analysis of differentially expressed genes revealed a strong association between P4/E2 treatment and downregulated expression of genes involved in cell communication, signal transduction, channel activity, inflammatory response, and differentiation. Upregulated processes included cell survival, gene transcription, steroid hormone biosynthesis, muscle development, insulin receptor signaling, and cell growth.

Toll-Like Receptor 4 Is an Essential Upstream Regulator of On-Time Parturition and Perinatal Viability in Mice

An inflammatory response is instrumental in the physiological process of parturition but the upstream signals initiating inflammation are undefined. Because endogenous ligands for Toll-like receptor 4 (TLR4) are released in late gestation, we hypothesized that on-time labor requires TLR4 signaling, to trigger a cytokine and leukocyte response and accelerate the parturition cascade. In pregnant TLR4-deficient (Tlr4-/-) mice, average gestation length was extended by 13 hours and increased perinatal mortality was seen compared with wild-type controls. Quantification of cytokine and uterine activation gene expression showed that late gestation induction of Il1b, Il6, Il12b, and Tnf expression seen in control placenta and fetal membranes was disrupted in Tlr4-/- mice, and accompanied by a transient delay in expression of uterine activation genes, including prostaglandin F receptor, oxytocin receptor, and connexin-43. Leukocyte populations were altered before birth in TLR4-deficient females, with fewer neutrophils and macrophages in the placenta, and fewer dendritic cells and more regulatory T cells in the myometrium. Administration of TLR4 ligand lipopolysaccharide to pregnant wild-type mice induced cytokine expression and fetal loss, whereas Tlr4-/- pregnancies were protected. The small molecule TLR4 antagonist (+)-naloxone increased mean duration of gestation by 16 hours in wild-type mice. Collectively, these data demonstrate that TLR4 is a key upstream regulator of the inflammatory response acting to drive uterine activation and control the timing of labor. Because causal pathways for term and preterm labor converge with TLR4, interventions to manipulate TLR4 signaling may have therapeutic utility for women at risk of preterm labor, or in postterm pregnancy.

Specific inhibition of c-Jun N-terminal kinase delays preterm labour and reduces mortality

Preterm labour (PTL) is commonly associated with infection and/or inflammation. Lipopolysaccharide (LPS) from different bacteria can be used to independently or mutually activate Jun N-terminal kinase (JNK)/AP1- or NF-κB-driven inflammatory pathways that lead to PTL. Previous studies using Salmonella abortus LPS, which activates both JNK/AP-1 and NF-κB, showed that selective inhibition of NF-κB delays labour and improves pup outcome. Where labour is induced using Escherichia coli LPS (O111), which upregulates JNK/AP-1 but not NF-κB, inhibition of JNK/AP-1 activation also delays labour. In this study, to determine the potential role of JNK as a therapeutic target in PTL, we investigated the specific contribution of JNK signalling to S. Abortus LPS-induced PTL in mice. Intrauterine administration of S. Abortus LPS to pregnant mice resulted in the activation of JNK in the maternal uterus and fetal brain, upregulation of pro-inflammatory proteins COX-2, CXCL1, and CCL2, phosphorylation of cPLA2 in myometrium, and induction of PTL. Specific inhibition of JNK by co-administration of specific D-JNK inhibitory peptide (D-JNKI) delayed LPS-induced preterm delivery and reduced fetal mortality. This is associated with inhibition of myometrial cPLA2 phosphorylation and proinflammatory proteins synthesis. In addition, we report that D-JNKI inhibits the activation of JNK/JNK3 and caspase-3, which are important mediators of neural cell death in the neonatal brain. Our data demonstrate that specific inhibition of TLR4-activated JNK signalling pathways has potential as a therapeutic approach in the management of infection/inflammation-associated PTL and prevention of the associated detrimental effects to the neonatal brain.

The Relationship Between Plasma Inflammatory Cytokines and Labor Pain

BACKGROUND

Proinflammatory cytokines are increased in maternal blood at term pregnancy and are associated with cervical ripening and the initiation of labor. We hypothesize that maternal plasma cytokines also affect the sensitivity to labor pain.

METHODS

By using a previously validated model describing labor pain, we used a deidentified database derived from healthy nulliparous parturients who delivered singleton pregnancies at term. Numerical rating scores for pain were recorded after the onset of regular contractions using an 11-point scale. Maternal blood was drawn for the measurement of interleukin (IL)-1β, IL-4, IL-6, IL-8, and IL-10; interferon-γ; and tumor necrosis factor-α on admission or at the onset of painful contractions, whichever occurred later. Individual demographic, physiognomic, and cytokine variables that significantly affected labor pain at P < 0.05 were reported and included stepwise into a multivariable model.

RESULTS

One hundred sixty parturients provided 411 numerical analog scores for pain that were evaluated with our model. The relationship between numerical analog scores and cervical dilation was significantly affected by the type of membrane rupture, membrane status, induction, oxytocin administration, maternal race, and plasma IL-1β concentration as individual variables. Only the association between the highest IL-1β quartile and slower acceleration of pain during labor remained significant in the multivariate model (P = 0.0003). Women with IL-1β concentration in the highest quartile arrived at the labor room with a more dilated cervix than those with lower plasma concentrations of IL-1β (5.1 ± 3.0 vs 4.1 ± 2.6 cm; P < 0.02) and had faster labor progress.

CONCLUSIONS

Inflammatory cytokines including IL-1β play a role in cervical ripening. High maternal plasma concentrations of IL-1β may serve as a marker of advanced cervical ripening and readiness for labor that proceeds with less pain.

Progestin-Containing Contraceptives Alter Expression of Host Defense-Related Genes of the Endometrium and Cervix

Epidemiological studies indicate that progestin-containing contraceptives increase susceptibility to HIV, although the underlying mechanisms involving the upper female reproductive tract are undefined. To determine the effects of depot medroxyprogesterone acetate (DMPA) and the levonorgestrel intrauterine system (LNG-IUS) on gene expression and physiology of human endometrial and cervical transformation zone (TZ), microarray analyses were performed on whole tissue biopsies. In endometrium, activated pathways included leukocyte chemotaxis, attachment, and inflammation in DMPA and LNG-IUS users, and individual genes included pattern recognition receptors, complement components, and other immune mediators. In cervical TZ, progestin treatment altered expression of tissue remodeling and viability but not immune function genes. Together, these results indicate that progestins influence expression of immune-related genes in endometrium relevant to local recruitment of HIV target cells with potential to increase susceptibility and underscore the importance of the upper reproductive tract when assessing the safety of contraceptive products.

Prevalence and clinical significance of sterile intra-amniotic inflammation in patients with preterm labor and intact membranes

PROBLEM

Inflammation and infection play a major role in preterm birth. The purpose of this study was to (i) determine the prevalence and clinical significance of sterile intra-amniotic inflammation and (ii) examine the relationship between amniotic fluid (AF) concentrations of high mobility group box-1 (HMGB1) and the interval from amniocentesis to delivery in patients with sterile intra-amniotic inflammation.

METHOD OF STUDY

AF samples obtained from 135 women with preterm labor and intact membranes were analyzed using cultivation techniques as well as broad-range PCR and mass spectrometry (PCR/ESI-MS). Sterile intra-amniotic inflammation was defined when patients with negative AF cultures and without evidence of microbial footprints had intra-amniotic inflammation (AF interleukin-6 ≥ 2.6 ng/mL).

RESULTS

(i) The frequency of sterile intra-amniotic inflammation was significantly greater than that of microbial-associated intra-amniotic inflammation [26% (35/135) versus 11% (15/135); (P = 0.005)], (ii) patients with sterile intra-amniotic inflammation delivered at comparable gestational ages had similar rates of acute placental inflammation and adverse neonatal outcomes as patients with microbial-associated intra-amniotic inflammation, and (iii) patients with sterile intra-amniotic inflammation and high AF concentrations of HMGB1 (≥8.55 ng/mL) delivered earlier than those with low AF concentrations of HMGB1 (P = 0.02).

CONCLUSION

(i) Sterile intra-amniotic inflammation is more frequent than microbial-associated intra-amniotic inflammation, and (ii) we propose that danger signals participate in sterile intra-amniotic inflammation in the setting of preterm labor.

The effect of a Foley catheter balloon on cervical ripening

The Foley catheter balloon may affect cervical ripening through changes in biochemical mediators by immunoassay and immunohistochemistry, when it is used for pre-induction cervical ripening. The aim of the study was to evaluate the changes in the biochemical mediators from the extra-amniotic space and immunohistochemistry in ripened cervical tissue after the insertion of a Foley catheter balloon (FCB) for pre-induction cervical ripening. A total of 18 pregnant women with a Bishop's score < 6, who were undergoing labour induction, were evaluated in this prospective study. The FCB was irrigated with 10 ml of phosphate buffered saline and the irrigant was collected 0, 2, 4 and 8 h after placement of the FCB or until spontaneous expulsion of the FCB occurred. Irrigant specimens were also collected from 10 spontaneous labouring (SL) women in the active phase of labour. The levels of interleukin (IL)-6, IL-8, matrix metalloproteinase (MMP)-8 and NO were measured. Cervical specimens were obtained from 12 women, including four undergoing induction; four SL and four non-pregnant (NP) women. Immunohistochemical staining was performed to localise hyaluronic acid synthase (HAS)-1, IL-6, IL-8, MMP-8, endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS). Results showed that the levels of IL-6, IL-8, and MMP-8 significantly increased over time in FCB group (p < 0.01). In the immunohistochemical analysis of cervical tissues, immunoreactivity of HAS-1 in the after FCB group was stronger than any of the other groups. The protein expressions of IL-6, IL-8, MMP-8, eNOS and iNOS were more prominent in the after FCB and SL groups than in the NP and the before FCB groups. iNOS was only observed in the after FCB and SL groups. It was concluded that FCB may affect cervical ripening through changes in biochemical mediators by immunoassay and immunohistochemistry, when it is used for pre-induction cervical ripening.

Central role for protein kinase C in oxytocin and epidermal growth factor stimulated cyclooxygenase 2 expression in human myometrial cells

BACKGROUND

Prostaglandins are important mediators of uterine contractility and cervical ripening during labour. Cyclooxygenase-2 (COX-2), also known as prostaglandin-endoperoxide synthase 2, is a rate limiting enzyme involved in the conversion of arachidonic acid into prostaglandins at parturition. In this paper, the pathways underlying agonist-induced cyclooxygenase-2 expression in human myometrial cells were studied.

RESULTS

Myometrial cells were stimulated with different agonists: oxytocin (OXT), epidermal growth factor (EGF), interleukin-1β (IL1β), and phorbol-12-myristate-13-acetate (PMA) alone and in the presence of specific signalling pathway inhibitors. The nuclear factor kappa-light-chain-enhancer of activated B cells (NFKB) pathway was inhibited by means of the IKK-2 inhibitor TPCA-1. Signalling through extracellular signal-regulated kinases (ERK) was inhibited using the MEK1/2 inhibitor PD-184352. Bisindolylmaleimide-I was used to inhibit protein kinase C (PKC) signalling. COX-2 expression and ERK phosphorylation were measured using immunoblotting.OXT induced COX-2 expression by activating PKC and ERK. EGF increased COX-2 expression via stimulation of PKC, ERK and NFKB. As expected, the pro-inflammatory cytokine IL1β induced COX-2 expression by activating PKC- and NFKB-dependent pathways. Stimulation of PKC directly with PMA provoked strong COX-2 expression.

CONCLUSIONS

PKC plays a central role in OXT and EGF induced COX-2 expression in human myometrial cells. However, other pathways, notably ERK and NFKB are also involved to an extent which depends on the type of agonist used.

Transcriptome interrogation of human myometrium identifies differentially expressed sense-antisense pairs of protein-coding and long non-coding RNA genes in spontaneous labor at term

OBJECTIVE

To identify differentially expressed long non-coding RNA (lncRNA) genes in human myometrium in women with spontaneous labor at term.

MATERIALS AND METHODS

Myometrium was obtained from women undergoing cesarean deliveries who were not in labor (n = 19) and women in spontaneous labor at term (n = 20). RNA was extracted and profiled using an Illumina® microarray platform. We have used computational approaches to bound the extent of long non-coding RNA representation on this platform, and to identify co-differentially expressed and correlated pairs of long non-coding RNA genes and protein-coding genes sharing the same genomic loci.

RESULTS

We identified co-differential expression and correlation at two genomic loci that contain coding-lncRNA gene pairs: SOCS2-AK054607 and LMCD1-NR_024065 in women in spontaneous labor at term. This co-differential expression and correlation was validated by qRT-PCR, an experimental method completely independent of the microarray analysis. Intriguingly, one of the two lncRNA genes differentially expressed in term labor had a key genomic structure element, a splice site, that lacked evolutionary conservation beyond primates.

CONCLUSIONS

We provide, for the first time, evidence for coordinated differential expression and correlation of cis-encoded antisense lncRNAs and protein-coding genes with known as well as novel roles in pregnancy in the myometrium of women in spontaneous labor at term.

Increased tissue levels of omega-3 polyunsaturated fatty acids prevents pathological preterm birth

Omega-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) have anti-inflammatory effects. Preterm birth is an important problem in modern obstetrics and one of the main causes is an inflammation. We here showed that abundance of omega-3 fatty acids reduced the incidence of preterm birth induced by LPS with fat-1 mice, capable of converting omega-6 to omega-3 fatty acids. We also indicated that the gene expression of IL-6 and IL-1β in uteruses and the number of cervical infiltrating macrophages were reduced in fat-1 mice. The analyses of lipid metabolomics showed the high level of 18-hydroxyeicosapentaenoate in fat-1 mice, which was derived from EPA and was metabolized to anti-inflammatory product named resolvin E3 (RvE3). We finally showed that the administration of RvE3 to LPS-exposed pregnant wild type mice lowered the incidence of preterm birth. Our data suggest that RvE3 could be a potential new therapeutic for the prevention of preterm birth.

Prokineticin 1 induces a pro-inflammatory response in murine fetal membranes but does not induce preterm delivery

The mechanisms that regulate the induction of term or preterm delivery (PTD) are not fully understood. Infection is known to play a role in the induction of pro-inflammatory cascades in uteroplacental tissues associated with preterm pathological parturition. Similar but not identical cascades are evident in term labour. In the current study, we used a mouse model to evaluate the role of prokineticins in term and preterm parturition. Prokineticins are multi-functioning secreted proteins that signal through G-protein-coupled receptors to induce gene expression, including genes important in inflammatory responses. Expression of prokineticins (Prok1 and Prok2) was quantified in murine uteroplacental tissues by QPCR in the days preceding labour (days 16-19). Prok1 mRNA expression increased significantly on D18 in fetal membranes (compared with D16) but not in uterus or placenta. Intrauterine injection of PROK1 on D17 induced fetal membrane mRNA expression of the pro-inflammatory mediators Il6, Il1b, Tnf, Cxcl2 and Cxcl5, which are not normally up-regulated until D19 of pregnancy. However, intrauterine injection of PROK1 did not result in PTD. As expected, injection of lipopolysaccharide (LPS) induced PTD, but this was not associated with changes in expression of Prok1 or its receptor (Prokr1) in fetal membranes. These results suggest that although Prok1 exhibits dynamic mRNA regulation in fetal membranes preceding labour and induces a pro-inflammatory response when injected into the uterus on D17, it is insufficient to induce PTD. Additionally, prokineticin up-regulation appears not to be part of the LPS-induced inflammatory response in mouse fetal membranes.