An experimental model for intraamniotic infection and preterm labor in rhesus monkeys

Re-framing the importance of Group B Streptococcus as a gut-resident pathobiont

Streptococcus agalactiae (Group B Streptococcus, GBS) is a Gram-positive bacterial species that causes disease in humans across the lifespan. While antibiotics are used to mitigate GBS infections, it is evident that antibiotics disrupt human microbiomes (which can predispose people to other diseases later in life), and antibiotic resistance in GBS is on the rise. Taken together, these unintended negative impacts of antibiotics highlight the need for precision approaches for minimizing GBS disease. One possible approach involves selectively depleting GBS in its commensal niches before it can cause disease at other body sites or be transmitted to at-risk individuals. One understudied commensal niche of GBS is the adult gastrointestinal (GI) tract, which may predispose colonization at other body sites in individuals at risk for GBS disease. However, a better understanding of the host-, microbiome-, and GBS-determined variables that dictate GBS GI carriage is needed before precise GI decolonization approaches can be developed. In this review, we synthesize current knowledge of the diverse body sites occupied by GBS as a pathogen and as a commensal. We summarize key molecular factors GBS utilizes to colonize different host-associated niches to inform future efforts to study GBS in the GI tract. We also discuss other GI commensals that are pathogenic in other body sites to emphasize the broader utility of precise de-colonization approaches for mitigating infections by GBS and other bacterial pathogens. Finally, we highlight how GBS treatments could be improved with a more holistic understanding of GBS enabled by continued GI-focused study.

The hormonal control of parturition

Parturition is a complex physiological process that must occur in a reliable manner and at an appropriate gestation stage to ensure a healthy newborn and mother. To this end, hormones that affect the function of the gravid uterus, especially progesterone (P4), 17β-estradiol (E2), oxytocin (OT), and prostaglandins (PGs), play pivotal roles. P4 via the nuclear P4 receptor (PR) promotes uterine quiescence and for most of pregnancy exerts a dominant block to labor. Loss of the P4 block to parturition in association with a gain in prolabor actions of E2 are key transitions in the hormonal cascade leading to parturition. P4 withdrawal can occur through various mechanisms depending on species and physiological context. Parturition in most species involves inflammation within the uterine tissues and especially at the maternal-fetal interface. Local PGs and other inflammatory mediators may initiate parturition by inducing P4 withdrawal. Withdrawal of the P4 block is coordinated with increased E2 actions to enhance uterotonic signals mediated by OT and PGs to promote uterine contractions, cervix softening, and membrane rupture, i.e., labor. This review examines recent advances in research to understand the hormonal control of parturition, with focus on the roles of P4, E2, PGs, OT, inflammatory cytokines, and placental peptide hormones together with evolutionary biology of and implications for clinical management of human parturition.

The vaginal immunoproteome for the prediction of spontaneous preterm birth: A retrospective longitudinal study

Background

Preterm birth is the leading cause of neonatal morbidity and mortality worldwide. Most cases of preterm birth occur spontaneously and result from preterm labor with intact (spontaneous preterm labor [sPTL]) or ruptured (preterm prelabor rupture of membranes [PPROM]) membranes. The prediction of spontaneous preterm birth (sPTB) remains underpowered due to its syndromic nature and the dearth of independent analyses of the vaginal host immune response. Thus, we conducted the largest longitudinal investigation targeting vaginal immune mediators, referred to herein as the immunoproteome, in a population at high risk for sPTB.

Methods

Vaginal swabs were collected across gestation from pregnant women who ultimately underwent term birth, sPTL, or PPROM. Cytokines, chemokines, growth factors, and antimicrobial peptides in the samples were quantified via specific and sensitive immunoassays. Predictive models were constructed from immune mediator concentrations.

Results

Throughout uncomplicated gestation, the vaginal immunoproteome harbors a cytokine network with a homeostatic profile. Yet, the vaginal immunoproteome is skewed toward a pro-inflammatory state in pregnant women who ultimately experience sPTL and PPROM. Such an inflammatory profile includes increased monocyte chemoattractants, cytokines indicative of macrophage and T-cell activation, and reduced antimicrobial proteins/peptides. The vaginal immunoproteome has improved predictive value over maternal characteristics alone for identifying women at risk for early (<34 weeks) sPTB.

Conclusions

The vaginal immunoproteome undergoes homeostatic changes throughout gestation and deviations from this shift are associated with sPTB. Furthermore, the vaginal immunoproteome can be leveraged as a potential biomarker for early sPTB, a subset of sPTB associated with extremely adverse neonatal outcomes.

Funding

This research was conducted by the Perinatology Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services (NICHD/NIH/DHHS) under contract HHSN275201300006C. ALT, KRT, and NGL were supported by the Wayne State University Perinatal Initiative in Maternal, Perinatal and Child Health.

Progesterone inactivation in decidual stromal cells: A mechanism for inflammation-induced parturition

The process of human parturition involves inflammation at the interface where fetal chorion trophoblast cells interact with maternal decidual stromal (DS) cells and maternal immune cells in the decidua (endometrium of pregnancy). This study tested the hypothesis that inflammation at the chorion-decidua interface (CDI) induces labor by negating the capacity for progesterone (P4) to block labor and that this is mediated by inactivation of P4 in DS cells by aldo-keto reductase family 1 member C1 (AKR1C1). In human, Rhesus macaque, and mouse CDI, AKR1C1 expression increased in association with term and preterm labor. In a human DS cell line and in explant cultures of term human fetal membranes containing the CDI, the prolabor inflammatory cytokine, interleukin-1ß (IL-1ß), and media conditioned by LPS-stimulated macrophages increased AKR1C1 expression and coordinately reduced nuclear P4 levels and P4 responsiveness. Loss of P4 responsiveness was overcome by inhibition of AKR1C1 activity, inhibition of AKR1C1 expression, and bypassing AKR1C1 activity with a P4 analog that is not metabolized by AKR1C1. Increased P4 activity in response to AKR1C1 inhibition was prevented by the P4 receptor antagonist RU486. Pharmacologic inhibition of AKR1C1 activity prevented parturition in a mouse model of inflammation-induced preterm parturition. The data suggest that inflammatory stimuli at the CDI drive labor by inducing AKR1C1-mediated P4 inactivation in DS cells and that inhibiting and/or bypassing of AKR1C1-mediated P4 inactivation is a plausible therapeutic strategy to mitigate the risk of inflammation-associated preterm birth.

Host-microbiome interactions in distinct subsets of preterm labor and birth

Preterm birth, the leading cause of perinatal morbidity, often follows premature labor, a syndrome whose prevention remains a challenge. To better understand the relationship between premature labor and host-microbiome interactions, we conducted a mechanistic investigation using three preterm birth models. We report that intra-amniotic delivery of LPS triggers inflammatory responses in the amniotic cavity and cervico-vaginal microenvironment, causing vaginal microbiome changes and signs of active labor. Intra-amniotic IL-1α delivery causes a moderate inflammatory response in the amniotic cavity but increasing inflammation in the cervico-vaginal space, leading to vaginal microbiome disruption and signs of active labor. Conversely, progesterone action blockade by RU-486 triggers local immune responses accompanying signs of active labor without altering the vaginal microbiome. Preterm labor facilitates ascension of cervico-vaginal bacteria into the amniotic cavity, regardless of stimulus. This study provides compelling mechanistic insights into the dynamic host-microbiome interactions within the cervico-vaginal microenvironment that accompany premature labor and birth.

Association between interleukin-6 and preterm birth: a meta-analysis

BACKGROUND

Interleukin (IL)-6 is a pro-inflammatory cytokine that plays an important role in preterm birth (PTB), Several meta-analyses investigated the association between IL-6 and PTB, but definitive conclusion has not yet been achieved. This updated meta-analysis aimed to ascertain the association between IL-6 and PTB by examining IL-6 levels in both normal birth and PTB groups.

MATERIAL AND METHODS

Prospective cohort studies were retrieved in PubMed, Embase, and the Cochrane library from their inception until 18 February 2020. The primary outcome was the association between IL-6 and PTB, and secondary outcomes were the association between IL-6 and spontaneous PTB.

RESULTS

Nine studies involving 1904 patients were included. Overall, IL-6 from different sample types (maternal blood, amniotic fluid and cervicovaginal fluid) was associated with PTB (standard mean difference [SMD]: 0.86, 95% confidence interval [CI]: 0.32 to 1.39, p < 0.001). Furthermore, the association was significant for IL-6 only in amniotic fluid (SMD: 1.87, 95%CI: 0.82 to 2.93, p < 0.001) and cervicovaginal fluid (SMD: 0.46, 95%CI: 0.09 to 0.84, p = 0.022), but not significant in maternal blood (SMD: -0.11, 95%CI: -0.57 to 0.34, p = 0.623). In addition, IL-6 was also associated with spontaneous PTB (SMD: 1.57, 95% CI: 0.18 to 2.95, p < 0.001).

CONCLUSIONS

Based on the available evidence, IL-6 in amniotic fluid and cervicovaginal fluid might be useful for predicting preterm birth.

Fetal Cardiac Hemodynamic and Sonographic Anomalies in Maternal COVID-19 Infection Depending on Vaccination Status-Polish Multicenter Cohort Study

Most obstetrical studies have focused on maternal response to the SARS-CoV-2 virus but much less is known about the effect of COVID-19 on fetal physiology. We aimed to evaluate the effect of the maternal SARS-CoV-2 infection on the fetal homeostasis with the use of detailed ultrasonography and echocardiography and consideration of the effect of vaccination. This was a multi-center study of fetuses who had prenatal detailed ultrasound and echocardiographic examinations performed by fetal cardiology specialists. The subjects were divided based on the COVID vaccination status (vaccinated women who did not have COVID-group V, unvaccinated women who had COVID-group UV, and unvaccinated women who did not have COVID-control group). We evaluated the ultrasound and echocardiography results obtained. The study group included 237 gravidas from four prenatal cardiology centers. In the group of fetuses with normal heart anatomy, normal cardiovascular function had 147 (81%) fetuses and functional cardiovascular anomalies were present in 35 (19%) cases. Functional cardiovascular anomalies were present in 11 (16%) fetuses in the V group, 19 (47%) fetuses in the UV group and 5 (8%) fetuses in the control group (p < 0.01). There were 56 (24%) fetuses with extracardiac anomalies. Extracardiac anomalies were present in 20 (22%) fetuses in the V group, 22 (45%) fetuses of the UV group and in 14 (14%) fetuses in the control group (p < 0.01). Our study has proved that maternal COVID-19 infection can affect the fetal physiology and mild cardiac and extracardiac markers detected by fetal ultrasonography and echocardiography. Moreover, maternal vaccination results in lower occurrence of these findings in fetuses.

Relationship of maternal inflammatory response and fetal inflammatory response to duration and intensity of intra-amniotic infection and inflammation

INTRODUCTION

We aimed to use two indices, amniotic fluid interleukin-6 (IL-6) concentration at diagnosis and diagnosis-to-delivery interval, to clarify the frequencies of maternal inflammatory response (MIR) and fetal inflammatory response (FIR) in the placenta of patients with intra-amniotic infection and intra-amniotic inflammation (IAI).

METHODS

This is a single-center retrospective cohort study. From August 2014 to April 2020, participants were diagnosed with IAI with or without microbial invasion of the amniotic cavity (MIAC) using amniocentesis. IAI was defined as concentrations of amniotic IL-6 ≥ 2.6 ng/mL. MIAC was defined as a positive amniotic fluid culture. IAI with MIAC was defined as an intra-amniotic infection. We calculated the cut-off values for IL-6 concentration in the amniotic fluid at diagnosis and the diagnosis-to-delivery interval for MIR-positive cases among those with intra-amniotic infection.

RESULTS

The amniotic fluid IL-6 concentration at diagnosis and diagnosis-to-delivery interval were 15.8 ng/mL and 12 h, respectively. Among cases with intra-amniotic infection, MIR was 98% (52/53) positive, i.e., when either of the two cut-off values was exceeded. There were no significant differences between the frequencies of MIR and FIR. In cases with IAI but no MIAC, the frequencies of MIR and FIR were significantly lower than those with intra-amniotic infection, except when neither of the two cut-off values was exceeded.

DISCUSSION

We clarified the MIR- and FIR-positive cases in intra-amniotic infection and cases with IAI but no MIAC according to condition, including the diagnosis-to-delivery interval.

Maternal urogenital infection and fetal heart functional assessment - what is the missing link?

OBJECTIVES

Maternal urogenital infections during pregnancy are worldwide frequent problem. The aim was to analyze influence of maternal genitourinary infection on fetal cardiac function, pregnancy development and obstetrical outcomes.

METHODS

This was a single-center cohort study on fetuses (average at 28th week) in two groups: with maternal urogenital infections (study group n=49) and control group with no infections (n=59). Parvovirus B19, toxoplasmosis, cytomegalovirus, herpes simplex infections, congenital malformations, fetal growth restriction, chronic maternal diseases, as well as patients with body mass index (BMI) >25 kg/m2 were excluded. We analyzed: maternal age, time of delivery, neonatal birth weight, Apgar scores, average time of hospitalization of newborns after birth and several fetal echocardiographic parameters.

RESULTS

The only statistical differences was found for shorter isovolumetric relaxation time (IRT) (40 ± 10 vs. 45 ± 9; p=0.03) and longer ejection time (ET) [ms] for right ventricle (RV) (176 ± 24 vs. 164 ± 18; p=0.01). Thick placenta was observed more frequent in study group than in controls (36.7 vs. 16.9%; p= 0.02).

CONCLUSIONS

The missing link for explanation of these findings was coincidence with thick placenta. This is probably the first observation suggesting that thick placenta (>5 cm) may affect fetal RV function in normal heart anatomy: prolongation of right ventricular ET and shortening of fetal right ventricular IVRT.

Roles of human trophoblasts' pattern recognition receptors in host defense and pregnancy complications

The immune system in pregnancy is able to protect pregnant mothers and fetuses from pathogenic microorganisms even while permitting the mother to tolerate the semi-allogenic fetus. Trophoblasts, which are fetal-derived placental cells, play a central role on both sides of this duality at the maternal-fetal interface. In brief, the trophoblasts express pattern recognition receptors (PRRs) and are involved in the local innate immune response in the placenta. That response eliminates pathogenic microbes but also causes tissue damage. In this review, we summarize the research findings to date regarding the roles of those human trophoblast PRRs. Multiple types of PRRs (Toll-like receptors, Nod-like receptors, and RIG-I-like receptors) are expressed in the placenta and on trophoblasts. Trophoblasts' PRRs participate in protecting the fetus against viruses, bacteria, and parasites by triggering production of proinflammatory cytokines and chemokines in the placenta. On the negative side, PRR signaling in trophoblasts can also initiate inflammation and trophoblast cell death, which can lead to placental inflammation-associated pregnancy complications such as preeclampsia, anti-phospholipid antibody syndrome, and miscarriage. Further elucidation of these dual roles of trophoblasts' PRRs may shed light on the mechanisms by which fetuses are protected against congenital infections and also give us a better understanding of the etiologies of pregnancy complications, which can help us prevent/reduce adverse prenatal/neonatal outcomes.

Progesterone withdrawal and parturition

The steroid hormone progesterone (P4), acting via the nuclear P4 receptors (PRs) in uterine cells, is essential for the establishment and maintenance of pregnancy. P4/PR signaling maintains pregnancy by promoting uterine quiescence and blocking the contractions of labor. Withdrawal of the P4/PR block to labor induces parturition. The success of pregnancy requires the timely birth of a mature neonate to a healthy mother, and to this end, the mechanism by which the P4/PR block is withdrawn, and how that process is physiologically controlled is critical. This review examines current understanding of cell and molecular biology of P4/PR withdrawal in the control of parturition.

The amniotic fluid proteome predicts imminent preterm delivery in asymptomatic women with a short cervix

Preterm birth, the leading cause of perinatal morbidity and mortality, is associated with increased risk of short- and long-term adverse outcomes. For women identified as at risk for preterm birth attributable to a sonographic short cervix, the determination of imminent delivery is crucial for patient management. The current study aimed to identify amniotic fluid (AF) proteins that could predict imminent delivery in asymptomatic patients with a short cervix. This retrospective cohort study included women enrolled between May 2002 and September 2015 who were diagnosed with a sonographic short cervix (< 25 mm) at 16–32 weeks of gestation. Amniocenteses were performed to exclude intra-amniotic infection; none of the women included had clinical signs of infection or labor at the time of amniocentesis. An aptamer-based multiplex platform was used to profile 1310 AF proteins, and the differential protein abundance between women who delivered within two weeks from amniocentesis, and those who did not, was determined. The analysis included adjustment for quantitative cervical length and control of the false-positive rate at 10%. The area under the receiver operating characteristic curve was calculated to determine whether protein abundance in combination with cervical length improved the prediction of imminent preterm delivery as compared to cervical length alone. Of the 1,310 proteins profiled in AF, 17 were differentially abundant in women destined to deliver within two weeks of amniocentesis independently of the cervical length (adjusted p-value < 0.10). The decreased abundance of SNAP25 and the increased abundance of GPI, PTPN11, OLR1, ENO1, GAPDH, CHI3L1, RETN, CSF3, LCN2, CXCL1, CXCL8, PGLYRP1, LDHB, IL6, MMP8, and PRTN3 were associated with an increased risk of imminent delivery (odds ratio > 1.5 for each). The sensitivity at a 10% false-positive rate for the prediction of imminent delivery by a quantitative cervical length alone was 38%, yet it increased to 79% when combined with the abundance of four AF proteins (CXCL8, SNAP25, PTPN11, and MMP8). Neutrophil-mediated immunity, neutrophil activation, granulocyte activation, myeloid leukocyte activation, and myeloid leukocyte-mediated immunity were biological processes impacted by protein dysregulation in women destined to deliver within two weeks of diagnosis. The combination of AF protein abundance and quantitative cervical length improves prediction of the timing of delivery compared to cervical length alone, among women with a sonographic short cervix.

Non-invasive prediction of histologic chorioamnionitis using maternal serum markers in women with preterm prelabour rupture of membranes

PROBLEM

This study aimed to evaluate and compare the predictive accuracy of serum markers for histological chorioamnionitis (HCA) among women with preterm prelabour rupture of membranes (PPROM), and to develop a nomogram prediction model to minimize the damage of the disease.

METHOD OF STUDY

This case-control study included 153 pregnant women with PPROM with a gestational age of 20⁺⁰ ∼ 36⁺⁶ weeks. The subjects were assigned into two groups: PPROM with and without HCA. According to the results of Logistic regression analysis, the predictive equation and nomogram were generated using key parameters, and the discrimination and consistency of the model were evaluated by receiver operating characteristic (ROC) curves and calibration curves.

RESULTS

From 153 subjects with PPROM, 77 developed HCA. Compared with the PPROM without HCA group, the CRP, PCT and NLR were significantly higher in HCA group (P<0.001), and the CRP had the highest predictive value. The area under the curve (AUC) of the prediction model was 0.873, and the sensitivity and specificity of predicting HCA were 68.8% and 92.1%, respectively. And the calibration curves fitted well with the realistic situation.

CONCLUSION

Maternal serum CRP and NLR could be used as predictive biomarkers for HCA in women with PPROM, while PCT needs to be further explored due to its slightly lower predictive value. Our serum markers and gestational age at PPROM could be used as a non-invasive and convenient method to predict HCA in women with PPROM. This article is protected by copyright. All rights reserved.

Mechanisms of group B Streptococcus-mediated preterm birth: lessons learnt from animal models

Group B Streptococcus (GBS) is an opportunistic pathogenic bacterium which upon colonization in the female reproductive tract can cause preterm births, fetal injury, and demise. Several determinants for GBS pathogenesis have been explored so far through the studies using animal models ranging from mice to non-human primates. The results from these experimental data have identified outer membrane vesicles, β-hemolysin, hyaluronidase, and Cas9 of GBS as major virulence factors leading to preterm births. Most of these factors drive inflammation through activation of NLRP3 and elevated production of IL1-β. However, the absence of one of the factors from the pathogen reduces but does not completely abolish the pathogenesis of GBS suggesting the involvement of more than one factor in causing preterm birth. This makes further exploration of other virulence factors of GBS pathogenesis important in gaining an insight into the mechanistic basis of GBS-mediated preterm births.

Lay summary

Group B Streptococcus (GBS) is a pathogenic bacteria whose infection in the reproductive tract during pregnancy can cause premature delivery. This bacterial infection is one of the major causes of death of mother and baby during pregnancy, and the bacteria is prevalent in all parts of the world. This makes the research on GBS so important and many of the mechanisms behind GBS infection during pregnancy still remain unexplored. In this review, we have outlined how various animal models contributed in finding the mechanism of GBS pathogenesis. The review also focuses on compiling various virulence factors which makes GBS pathogenic in the vulnerable. Understanding the mechanisms of infection by GBS will be crucial in developing drugs and vaccines to protect against the harmful effects of the bacteria.

Clarithromycin prevents preterm birth and neonatal mortality by dampening alarmin-induced maternal–fetal inflammation in mice

Background

One of every four preterm neonates is born to a woman with sterile intra-amniotic inflammation (inflammatory process induced by alarmins); yet, this clinical condition still lacks treatment. Herein, we utilized an established murine model of sterile intra-amniotic inflammation induced by the alarmin high-mobility group box-1 (HMGB1) to evaluate whether treatment with clarithromycin prevents preterm birth and adverse neonatal outcomes by dampening maternal and fetal inflammatory responses.

Methods

Pregnant mice were intra-amniotically injected with HMGB1 under ultrasound guidance and treated with clarithromycin or vehicle control, and pregnancy and neonatal outcomes were recorded (n = 15 dams each). Additionally, amniotic fluid, placenta, uterine decidua, cervix, and fetal tissues were collected prior to preterm birth for determination of the inflammatory status (n = 7–8 dams each).

Results

Clarithromycin extended the gestational length, reduced the rate of preterm birth, and improved neonatal mortality induced by HMGB1. Clarithromycin prevented preterm birth by interfering with the common cascade of parturition as evidenced by dysregulated expression of contractility-associated proteins and inflammatory mediators in the intra-uterine tissues. Notably, clarithromycin improved neonatal survival by dampening inflammation in the placenta as well as in the fetal lung, intestine, liver, and spleen.

Conclusions

Clarithromycin prevents preterm birth and improves neonatal survival in an animal model of sterile intra-amniotic inflammation, demonstrating the potential utility of this macrolide for treating women with this clinical condition, which currently lacks a therapeutic intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04764-2.

Distinct Cellular Immune Responses to SARS-CoV-2 in Pregnant Women

Pregnant women are at increased risk of adverse outcomes, including preeclampsia and preterm birth, that may result from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Pregnancy imprints specific maternal immune responses that can modulate host susceptibility to microbial infection; therefore, recent studies have focused on the humoral response against SARS-CoV-2 in pregnant women. However, the pregnancy-specific cellular immune responses triggered by SARS-CoV-2 infection are poorly understood. In this study, we undertook an extensive in vitro investigation to determine the cellular immune responses to SARS-CoV-2 particles and proteins/peptides in pregnant women. First, we show that SARS-CoV-2 particles do not alter the pregnancy-specific oxidative burst of neutrophils and monocytes. Yet, SARS-CoV-2 particles/proteins shift monocyte activation from the classical to intermediate states in pregnant, but not in nonpregnant, women. Furthermore, SARS-CoV-2 proteins, but not particles or peptide pools, mildly enhance T cell activation during pregnancy. As expected, B cell phenotypes are heavily modulated by SARS-CoV-2 particles in all women; yet, pregnancy itself further modified such responses in these adaptive immune cells. Lastly, we report that pregnancy itself governs cytokine responses in the maternal circulation, of which IFN-β and IL-8 were diminished upon SARS-CoV-2 challenge. Collectively, these findings highlight the differential in vitro responses to SARS-CoV-2 in pregnant and nonpregnant women and shed light on the immune mechanisms implicated in coronavirus disease 2019 during pregnancy.

IL-22 Plays a Dual Role in the Amniotic Cavity: Tissue Injury and Host Defense against Microbes in Preterm Labor

IL-22 is a multifaceted cytokine with both pro- and anti-inflammatory functions that is implicated in multiple pathologies. However, the role of IL-22 in maternal-fetal immunity in late gestation is poorly understood. In this study, we first showed that IL-22+ T cells coexpressing retinoic acid-related orphan receptor γt (ROR-γt) are enriched at the human maternal-fetal interface of women with preterm labor and birth, which was confirmed by in silico analysis of single-cell RNA sequencing data. T cell activation leading to preterm birth in mice was preceded by a surge in IL-22 in the maternal circulation and amniotic cavity; however, systemic administration of IL-22 in mice did not induce adverse perinatal outcomes. Next, using an ex vivo human system, we showed that IL-22 can cross from the choriodecidua to the intra-amniotic space, where its receptors (Il22ra1, Il10rb, and Il22ra2) are highly expressed by murine gestational and fetal tissues in late pregnancy. Importantly, amniotic fluid concentrations of IL-22 were elevated in women with sterile or microbial intra-amniotic inflammation, suggesting a dual role for this cytokine. The intra-amniotic administration of IL-22 alone shortened gestation and caused neonatal death in mice, with the latter outcome involving lung maturation and inflammation. IL-22 plays a role in host response by participating in the intra-amniotic inflammatory milieu preceding Ureaplasma parvum-induced preterm birth in mice, which was rescued by the deficiency of IL-22. Collectively, these data show that IL-22 alone is capable of causing fetal injury leading to neonatal death and can participate in host defense against microbial invasion of the amniotic cavity leading to preterm labor and birth.

Dexmedetomidine and LPS co-treatment attenuates inflammatory response on WISH cells via inhibition of p38/NF-κB signaling pathway

Background

Inflammatory dental diseases that occur during pregnancy can cause preterm labor and/or intrauterine growth restriction. Therefore, proactive treatment of dental diseases is necessary during pregnancy. Dexmedetomidine (DEX) is a widely used sedative in the dental field, but research on the effect of DEX on pregnancy is currently insufficient. In this study, we investigated the effects of co-treatment with DEX and lipopolysaccharide (LPS) on inflammatory responses in human amnion-derived WISH cells.

Methods

Human amnion-derived WISH cells were treated with 0.001, 0.01, 0.1, and 1 µg/mL DEX with 1 µg/mL LPS for 24 h. Cytotoxicity of WISH cells was evaluated by 3-(4,5-dimethylthiazol)-2,5-diphenyltetrazolium bromide (MTT) assay. The protein expression of cyclooxygenase-2 (COX-2), prostaglandin E₂ (PGE₂), p38, and nuclear factor kappa B (NF-κB) was examined by western blot analysis. The mRNA expression of pro-inflammatory cytokines such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α was analyzed by real-time quantitative polymerase chain reaction.

Results

Co-treatment with DEX and LPS showed no cytotoxicity in the WISH cells. The mRNA expression of IL-1β and TNF-α decreased after co-treatment with DEX and LPS. DEX and LPS co-treatment decreased the protein expression of COX-2, PGE₂, phospho-p38, and phospho-NF-κB in WISH cells.

Conclusion

Co-treatment with DEX and LPS suppressed the expression of COX-2 and PGE₂, as well as pro-inflammatory cytokines such as IL-1β and TNF-α in WISH cells. In addition, the anti-inflammatory effect of DEX and LPS co-treatment was mediated by the inhibition of p38/NF-κB activation.

The alarmin S100A12 causes sterile inflammation of the human chorioamniotic membranes as well as preterm birth and neonatal mortality in mice†

Sterile inflammation is triggered by danger signals, or alarmins, released upon cellular stress or necrosis. Sterile inflammation occurring in the amniotic cavity (i.e. sterile intra-amniotic inflammation) is frequently observed in women with spontaneous preterm labor resulting in preterm birth, the leading cause of neonatal morbidity and mortality worldwide; this condition is associated with increased amniotic fluid concentrations of alarmins. However, the mechanisms whereby alarmins induce sterile intra-amniotic inflammation are still under investigation. Herein, we investigated the mechanisms whereby the alarmin S100A12 induces inflammation of the human chorioamniotic membranes in vitro and used a mouse model to establish a causal link between this alarmin and adverse perinatal outcomes. We report that S100A12 initiates sterile inflammation in the chorioamniotic membranes by upregulating the expression of inflammatory mediators such as pro-inflammatory cytokines and pattern recognition receptors. Importantly, S100A12 induced the priming and activation of inflammasomes, resulting in caspase-1 cleavage and the subsequent release of mature IL-1β by the chorioamniotic membranes. This alarmin also caused the activation of the chorioamniotic membranes by promoting MMP-2 activity and collagen degradation. Lastly, the ultrasound-guided intra-amniotic injection of S100A12 at specific concentrations observed in the majority of women with sterile intra-amniotic inflammation induced preterm birth (rates: 17% at 200 ng/sac; 25% at 300 ng/sac; 25% at 400 ng/sac) and neonatal mortality (rates: 22% at 200 ng/sac; 44% at 300 ng/sac; 31% at 400 ng/sac), thus demonstrating a causal link between this alarmin and adverse perinatal outcomes. Collectively, our findings shed light on the inflammatory responses driven by alarmins in the chorioamniotic membranes, providing insight into the immune mechanisms leading to preterm birth in women with sterile intra-amniotic inflammation.

Bacteria in the amniotic fluid without inflammation: early colonization vs. contamination

OBJECTIVES

Intra-amniotic infection, defined by the presence of microorganisms in the amniotic cavity, is often accompanied by intra-amniotic inflammation. Occasionally, laboratories report the growth of bacteria or the presence of microbial nucleic acids in amniotic fluid in the absence of intra-amniotic inflammation. This study was conducted to determine the clinical significance of the presence of bacteria in amniotic fluid samples in the absence of intra-amniotic inflammation.

METHODS

A retrospective cross-sectional study included 360 patients with preterm labor and intact membranes who underwent transabdominal amniocentesis for evaluation of the microbial state of the amniotic cavity as well as intra-amniotic inflammation. Cultivation techniques were used to isolate microorganisms, and broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS) was utilized to detect the nucleic acids of bacteria, viruses, and fungi.

RESULTS

Patients whose amniotic fluid samples evinced microorganisms but did not indicate inflammation had a similar perinatal outcome to those without microorganisms or inflammation [amniocentesis-to-delivery interval (p=0.31), spontaneous preterm birth before 34 weeks (p=0.83), acute placental inflammatory lesions (p=1), and composite neonatal morbidity (p=0.8)].

CONCLUSIONS

The isolation of microorganisms from a sample of amniotic fluid in the absence of intra-amniotic inflammation is indicative of a benign condition, which most likely represents contamination of the specimen during the collection procedure or laboratory processing rather than early colonization or infection.

Betamethasone as a potential treatment for preterm birth associated with sterile intra-amniotic inflammation: a murine study

OBJECTIVES

Preterm birth remains the leading cause of perinatal morbidity and mortality worldwide. Preterm birth is preceded by spontaneous preterm labor, which is commonly associated with sterile intra-amniotic inflammation; yet, no approved treatment exists for this clinical condition. Corticosteroids are the standard of care to improve neonatal outcomes in women at risk of preterm birth. Herein, we first validated our model of alarmin-induced preterm birth. Next, we investigated whether treatment with betamethasone could prevent preterm birth resulting from sterile intra-amniotic inflammation in mice.

METHODS

Under ultrasound guidance, the first cohort of dams received an intra-amniotic injection of the alarmin high-mobility group box-1 (HMGB1, n=10) or phosphate-buffered saline (PBS, n=9) as controls. A second cohort of dams received HMGB1 intra-amniotically and were subcutaneously treated with betamethasone (n=15) or vehicle (n=15). Dams were observed until delivery, and perinatal outcomes were observed.

RESULTS

Intra-amniotic HMGB1 reduced gestational length (p=0.04), inducing preterm birth in 40% (4/10) of cases, of which 100% (4/4) were categorized as late preterm births. Importantly, treatment with betamethasone extended the gestational length (p=0.02), thereby reducing the rate of preterm birth by 26.6% (from 33.3% [5/15] to 6.7% [1/15]). Treatment with betamethasone did not worsen the rate of neonatal mortality induced by HMGB1 or alter weight gain in the first three weeks of life.

CONCLUSIONS

Treatment with betamethasone prevents preterm birth induced by the alarmin HMGB1. This study supports the potential utility of betamethasone for treating women with sterile intra-amniotic inflammation.

Bacterial and Host Determinants of Group B Streptococcal Vaginal Colonization and Ascending Infection in Pregnancy

Group B streptococcus (GBS) is a gram-positive bacteria that asymptomatically colonizes the vaginal tract. However, during pregnancy maternal GBS colonization greatly predisposes the mother and baby to a wide range of adverse outcomes, including preterm birth (PTB), stillbirth, and neonatal infection. Although many mechanisms involved in GBS pathogenesis are partially elucidated, there is currently no approved GBS vaccine. The development of a safe and effective vaccine that can be administered during or prior to pregnancy remains a principal objective in the field, because current antibiotic-based therapeutic strategies do not eliminate all cases of invasive GBS infections. Herein, we review our understanding of GBS disease pathogenesis at the maternal-fetal interface with a focus on the bacterial virulence factors and host defenses that modulate the outcome of infection. We follow GBS along its path from an asymptomatic colonizer of the vagina to an invasive pathogen at the maternal-fetal interface, noting factors critical for vaginal colonization, ascending infection, and vertical transmission to the fetus. Finally, at each stage of infection we emphasize important host-pathogen interactions, which, if targeted therapeutically, may help to reduce the global burden of GBS.

Non-human Primate Models to Investigate Mechanisms of Infection-Associated Fetal and Pediatric Injury, Teratogenesis and Stillbirth

A wide array of pathogens has the potential to injure the fetus and induce teratogenesis, the process by which mutations in fetal somatic cells lead to congenital malformations. Rubella virus was the first infectious disease to be linked to congenital malformations due to an infection in pregnancy, which can include congenital cataracts, microcephaly, hearing impairment and congenital heart disease. Currently, human cytomegalovirus (HCMV) is the leading infectious cause of congenital malformations globally, affecting 1 in every 200 infants. However, our knowledge of teratogenic viruses and pathogens is far from complete. New emerging infectious diseases may induce teratogenesis, similar to Zika virus (ZIKV) that caused a global pandemic in 2016-2017; thousands of neonates were born with congenital microcephaly due to ZIKV exposure in utero, which also included a spectrum of injuries to the brain, eyes and spinal cord. In addition to congenital anomalies, permanent injury to fetal and neonatal organs, preterm birth, stillbirth and spontaneous abortion are known consequences of a broader group of infectious diseases including group B streptococcus (GBS), Listeria monocytogenes, Influenza A virus (IAV), and Human Immunodeficiency Virus (HIV). Animal models are crucial for determining the mechanism of how these various infectious diseases induce teratogenesis or organ injury, as well as testing novel therapeutics for fetal or neonatal protection. Other mammalian models differ in many respects from human pregnancy including placentation, labor physiology, reproductive tract anatomy, timeline of fetal development and reproductive toxicology. In contrast, non-human primates (NHP) most closely resemble human pregnancy and exhibit key similarities that make them ideal for research to discover the mechanisms of injury and for testing vaccines and therapeutics to prevent teratogenesis, fetal and neonatal injury and adverse pregnancy outcomes (e.g., stillbirth or spontaneous abortion). In this review, we emphasize key contributions of the NHP model pre-clinical research for ZIKV, HCMV, HIV, IAV, L. monocytogenes, Ureaplasma species, and GBS. This work represents the foundation for development and testing of preventative and therapeutic strategies to inhibit infectious injury of human fetuses and neonates.

RNA Sequencing Reveals Distinct Immune Responses in the Chorioamniotic Membranes of Women with Preterm Labor and Microbial or Sterile Intra-amniotic Inflammation

Preterm labor precedes premature birth, the leading cause of neonatal morbidity and mortality worldwide. Preterm labor can occur in the context of either microbe-associated intra-amniotic inflammation (i.e., intra-amniotic infection) or intra-amniotic inflammation in the absence of detectable microorganisms (i.e., sterile intra-amniotic inflammation). Both intra-amniotic infection and sterile intra-amniotic inflammation trigger local immune responses that have deleterious effects on fetal life. Yet, the extent of such immune responses in the fetal tissues surrounding the amniotic cavity (i.e., the chorioamniotic membranes) is poorly understood. By using RNA sequencing (RNA seq) as a discovery approach, we found that there were significant transcriptomic differences involving host response to pathogens in the chorioamniotic membranes of women with intra-amniotic infection compared to those from women without inflammation. In addition, the sterile or microbial nature of intra-amniotic inflammation was associated with distinct transcriptomic profiles in the chorioamniotic membranes. Moreover, the immune response in the chorioamniotic membranes of women with sterile intra-amniotic inflammation was milder in nature than that induced by microbes and involved the upregulation of alarmins and inflammasome-related molecules. Lastly, the presence of maternal and fetal inflammatory responses in the placenta was associated with the upregulation of immune processes in the chorioamniotic membranes. Collectively, these findings provide insight into the immune responses against microbes or alarmins that take place in the fetal tissues surrounding the amniotic cavity, shedding light on the immunobiology of preterm labor and birth.

Interleukin-6 in Amniotic Fluid: A Reliable Marker for Adverse Outcomes in Women in Preterm Labor and Intact Membranes

INTRODUCTION

Amniotic fluid (AF) interleukin-6 (IL-6) concentration has been associated to preterm delivery and perinatal morbidity and mortality in women with preterm labor and intact membranes. Nevertheless, the clinical significance of this biomarker of intra-amniotic inflammation (IAI) is still unclear due in part to the paucity of large studies.

METHODS

AF IL-6 concentrations were determined in 452 consecutive women with preterm labor and intact membranes, categorized into 3 groups: 302 without IAI (IL-6 of <2.6 ng/mL), 64 with mild IAI (IL-6 of 2.6-11.2 ng/mL), and 86 with severe IAI (IL-6 of ≥11.3 ng/mL).

RESULTS

The severe IAI group had a short pregnancy duration from amniocentesis to delivery (median 3 days) than in without IAI group (median 45 days); meanwhile, the mild IAI group had a latency that was intermediate to the severe and without IAI groups (median 9.5 days). As compared to women without IAI, women with mild and severe IAI had higher rates of preterm delivery at both <34 and <37 weeks of gestation and perinatal morbidity and mortality. Furthermore, the risk of various individual adverse outcomes (short latency from amniocentesis to delivery [at ≤3 days, ≤7 days, and ≤14 days], preterm delivery at both <34 and <37 weeks of gestation, histologic chorioamnionitis, respiratory distress syndrome, and congenital sepsis) was higher in women with severe IAI (OR ≥ 2.8), compared with women without IAI.

CONCLUSIONS

AF IL-6 concentrations appear to be suitable marker to assess the degree of IAI and are associated with increased risk of adverse outcomes.

Melatonin for the prevention of fetal injury associated with intrauterine inflammation

Intrauterine inflammation is shown to be associated with preterm birth, fetal inflammatory response syndrome, and other pregnancy-related comorbidities such as central nervous system diseases including cerebral palsy and periventricular leukomalacia, pulmonary diseases such as bronchopulmonary dysplasia and respiratory distress syndrome, and necrotizing enterocolitis, to name a few. Many animal studies on intrauterine inflammation demonstrate that ascending infection of reproductive organs or the production of proinflammatory cytokines by some stimuli in utero results in such manifestations. Melatonin, known for its primary function in maintaining circadian rhythm, is now recognized as one of the most potent antioxidant and anti-inflammatory drugs. In some studies, melatonin injection in pregnant animals with intrauterine inflammation significantly reduced the number of preterm births, the severity of structural disintegration of the fetal lungs observed in bronchopulmonary dysplasia, and perinatal brain injuries with improvement in neuromotor function. These implicated benefits of melatonin in pregnant women with intrauterine inflammation seem promising in many research studies, strongly supporting the hypothesis that melatonin has antioxidative and anti-inflammatory properties that can potentially be taken by pregnant women who are at risk of having intrauterine inflammation. In this review, the potential of melatonin for improving outcomes of the pregnancies with intrauterine inflammation will be discussed.

Abnormal uterine inflammation in obstetric syndromes: molecular insights into the role of chemokine decoy receptor D6 and inflammasome NLRP3

The adaptation of the uterine environment into a favorable immunological and inflammatory milieu is a physiological process needed in normal pregnancy. A uterine hyperinflammatory state, whether idiopathic or secondary to hormonal or organic uterine disorders (polycystic ovary syndromes, endometriosis/adenomyosis and fibroids), negatively influences the interactions between decidua and trophoblast, early in gestation, and between chorion and decidua later in pregnancy. Abnormal activation of uterine inflammatory pathways not only contributes to the pathogenesis of the obstetric syndromes, i.e. recurrent pregnancy loss (RPL), pre-term delivery (PTD) and pre-eclampsia (PE), but also to correlates with severity. In this review, we summarize recent advances in the knowledge of uterine molecular mechanisms of inflammatory modulation in normal pregnancy and obstetric syndromes (RPL, PTD and PE). In particular, we focus on two regulators of uterine/placental inflammation: the NLRP3 inflammasome and the chemokines decoy receptor D6. We performed comprehensive review of the literature in PubMed and Google Scholar databases from 1994 to 2018. The available evidence suggests that: (i) the expression of inflammasome NLRP3 is increased in the endometrium of women with unexplained RPL, in the chorioamniotic membranes of women with PTL and in the placenta of women with PE; (ii) there is a role for abnormal expression and function of D6 decoy receptor at the feto-maternal interface in cases of RPL and PTD and (iii) the function of placental D6 decoy receptor is impaired in PE. A wider comprehension of the inflammatory molecular mechanisms involved in the pathogenesis of the obstetric syndromes might lead to the identification of new potential therapeutic targets.

Hyaluronidase Impairs Neutrophil Function and Promotes Group B Streptococcus Invasion and Preterm Labor in Nonhuman Primates

Invasive bacterial infections during pregnancy are a major risk factor for preterm birth, stillbirth, and fetal injury. Group B streptococci (GBS) are Gram-positive bacteria that asymptomatically colonize the lower genital tract but infect the amniotic fluid and induce preterm birth or stillbirth. Experimental models that closely emulate human pregnancy are pivotal for the development of successful strategies to prevent these adverse pregnancy outcomes. Using a unique nonhuman primate model that mimics human pregnancy and informs temporal events surrounding amniotic cavity invasion and preterm labor, we show that the animals inoculated with hyaluronidase (HylB)-expressing GBS consistently exhibited microbial invasion into the amniotic cavity, fetal bacteremia, and preterm labor. Although delayed cytokine responses were observed at the maternal-fetal interface, increased prostaglandin and matrix metalloproteinase levels in these animals likely mediated preterm labor. HylB-proficient GBS dampened reactive oxygen species production and exhibited increased resistance to neutrophils compared to an isogenic mutant. Together, these findings demonstrate how a bacterial enzyme promotes GBS amniotic cavity invasion and preterm labor in a model that closely resembles human pregnancy.

RNA Sequencing Reveals Diverse Functions of Amniotic Fluid Neutrophils and Monocytes/Macrophages in Intra-Amniotic Infection

Intra-amniotic infection, the invasion of microbes into the amniotic cavity resulting in inflammation, is a clinical condition that can lead to adverse pregnancy outcomes for the mother and fetus as well as severe long-term neonatal morbidities. Despite much research focused on the consequences of intra-amniotic infection, there remains little knowledge about the innate immune cells that respond to invading microbes. We performed RNA-seq of sorted amniotic fluid neutrophils and monocytes/macrophages from women with intra-amniotic infection to determine the transcriptomic differences between these innate immune cells. Further, we sought to identify specific transcriptomic pathways that were significantly altered by the maternal or fetal origin of amniotic fluid neutrophils and monocytes/macrophages, the presence of a severe fetal inflammatory response, and pregnancy outcome (i.e., preterm or term delivery). We show that significant transcriptomic differences exist between amniotic fluid neutrophils and monocytes/macrophages from women with intra-amniotic infection, indicating the distinct roles these cells play. The transcriptome of amniotic fluid immune cells varies based on their maternal or fetal origin, and the significant transcriptomic differences between fetal and maternal monocytes/macrophages imply that those of fetal origin exhibit impaired functions. Notably, transcriptomic changes in amniotic fluid monocytes/macrophages suggest that these immune cells collaborate with neutrophils in the trafficking of fetal leukocytes throughout the umbilical cord (i.e., funisitis). Finally, amniotic fluid neutrophils and monocytes/macrophages from preterm deliveries display enhanced transcriptional activity compared to those from term deliveries, highlighting the protective role of these cells during this vulnerable period. Collectively, these findings demonstrate the underlying complexity of local innate immune responses in women with intra-amniotic infection and provide new insights into the functions of neutrophils and monocytes/macrophages in the amniotic cavity.

Cervical stitch (cerclage) in combination with other treatments for preventing spontaneous preterm birth in singleton pregnancies

BACKGROUND

Preterm birth (PTB) remains the foremost global cause of perinatal morbidity and mortality. Thus, the prevention of spontaneous PTB still remains of critical importance. In an attempt to prevent PTB in singleton pregnancies, cervical cerclage, in combination with other treatments, has been advocated. This is because, cervical cerclage is an intervention that is commonly recommended in women with a short cervix at high risk of preterm birth but, despite this, many women still deliver prematurely, as the biological mechanism is incompletely understood. Additionally, previous Cochrane Reviews have been published on the effectiveness of cervical cerclage in singleton and multiple pregnancies, however, none has evaluated the effectiveness of using cervical cerclage in combination with other treatments.

OBJECTIVES

To assess whether antibiotics administration, vaginal pessary, reinforcing or second cerclage placement, tocolytic, progesterone, or other interventions at the time of cervical cerclage placement prolong singleton gestation in women at high risk of pregnancy loss based on prior history and/or ultrasound finding of 'short cervix' and/or physical examination. History-indicated cerclage is defined as a cerclage placed usually between 12 and 15 weeks gestation based solely on poor prior obstetrical history, e.g. multiple second trimester losses due to painless dilatation. Ultrasound-indicated cerclage is defined as a cerclage placed usually between 16 and 23 weeks gestation for transvaginal ultrasound cervical length < 20 mm in a woman without cervical dilatation. Physical exam-indicated cerclage is defined as a cerclage placed usually between 16 and 23 weeks gestation because of cervical dilatation of one or more centimetres detected on physical (manual) examination.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (26 September 2019), and reference lists of retrieved studies.

SELECTION CRITERIA

We included published, unpublished or ongoing randomised controlled trial (RCTs). Studies using a cluster-RCT design were also eligible for inclusion in this review but none were identified. We excluded quasi-RCTs (e.g. those randomised by date of birth or hospital number) and studies using a cross-over design. We also excluded studies that specified addition of the combination therapy after cervical cerclage because the woman subsequently became symptomatic. We included studies comparing cervical cerclage in combination with one, two or more interventions with cervical cerclage alone in singleton pregnancies.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts of all retrieved articles, selected studies for inclusion, extracted data, assessed risk of bias, and evaluated the certainty of the evidence for this review's main outcomes. Data were checked for accuracy. Standard Cochrane review methods were used throughout.

MAIN RESULTS

We identified two studies (involving a total of 73 women) comparing cervical cerclage alone to a different comparator. We also identified three ongoing studies (one investigating vaginal progesterone after cerclage, and two investigating cerclage plus pessary). One study (20 women), conducted in the UK, comparing cervical cerclage in combination with a tocolytic (salbutamol) with cervical cerclage alone in women with singleton pregnancy did not provide any useable data for this review. The other study (involving 53 women, with data from 50 women) took place in the USA and compared cervical cerclage in combination with a tocolytic (indomethacin) and antibiotics (cefazolin or clindamycin) versus cervical cerclage alone - this study did provide useable data for this review (and the study authors also provided additional data on request) but meta-analyses were not possible. This study was generally at a low risk of bias, apart from issues relating to blinding. We downgraded the certainty of evidence for serious risk of bias and imprecision (few participants, few events and wide 95% confidence intervals). Cervical cerclage in combination with an antibiotic and tocolytic versus cervical cerclage alone (one study, 50 women/babies) We are unclear about the effect of cervical cerclage in combination with antibiotics and a tocolytic compared with cervical cerclage alone on the risk of serious neonatal morbidity (RR 0.62, 95% CI 0.31 to 1.24; very low-certainty evidence); perinatal loss (data for miscarriage and stillbirth only - data not available for neonatal death) (RR 0.46, 95% CI 0.13 to 1.64; very low-certainty evidence) or preterm birth < 34 completed weeks of pregnancy (RR 0.78, 95% CI 0.44 to 1.40; very low-certainty evidence). There were no stillbirths (intrauterine death at 24 or more weeks). The trial authors did not report on the numbers of babies discharged home healthy (without obvious pathology) or on the risk of neonatal death.

AUTHORS' CONCLUSIONS

Currently, there is insufficient evidence to evaluate the effect of combining a tocolytic (indomethacin) and antibiotics (cefazolin/clindamycin) with cervical cerclage compared with cervical cerclage alone for preventing spontaneous PTB in women with singleton pregnancies. Future studies should recruit sufficient numbers of women to provide meaningful results and should measure neonatal death and numbers of babies discharged home healthy, as well as other important outcomes listed in this review. We did not identify any studies looking at other treatments in combination with cervical cerclage. Future research needs to focus on the role of other interventions such as vaginal support pessary, reinforcing or second cervical cerclage placement, 17-alpha-hydroxyprogesterone caproate or dydrogesterone or vaginal micronised progesterone, omega-3 long chain polyunsaturated fatty acid supplementation and bed rest.

Impact of maternal obesity on the risk of preterm delivery: insights into pathogenic mechanisms

PURPOSE

Preterm delivery (PTD) represents the leading cause of neonatal death and disability. Among risk factors for PTD, maternal obesity (MO) is becoming an ever more relevant condition in developed countries, although the mechanisms relating this condition to higher risk of PTD is not clear. Aim of this narrative review is to summarize evidences from clinical and translational research showing how MO might negatively impact on pregnancy and neonatal outcomes, particularly, by increasing the risk of PTD.

METHODS

We performed comprehensive review of the literature in PubMed and Google Scholar databases for studies from 1998 to 2018 linking MO to PTD and inflammation.

RESULTS

Chronic inflammatory status associated to increased synthesis of adipokines and cytokines from fat tissue has been shown in obesity. Obese women have a higher risk of both spontaneous and medically induced PTD. In about 50% of cases of spontaneous PTD, an infection-induced chorion amnionitis can be detected while in the remaining 50% a sterile inflammatory response has been described. Activation of uterine innate immunity system in intra-amniotic cavity and in chorioamniotic membranes might represent the missing link between MO and the pathogenesis of PTD.

CONCLUSION

Tissue inflammation might represent the pathogenic link between MO and increased occurrence of PTD. The achievement of pre-pregnancy normal maternal weight and body mass index is a fundamental aim of public health to reduce the incidence of PTD and get optimal reproductive outcomes.

Regulatory T Cells Play a Role in a Subset of Idiopathic Preterm Labor/Birth and Adverse Neonatal Outcomes

Regulatory T cells (Tregs) have been exhaustively investigated during early pregnancy; however, their role later in gestation is poorly understood. Herein, we report that functional Tregs are reduced at the maternal-fetal interface in a subset of women with idiopathic preterm labor/birth, which is accompanied by a concomitant increase in Tc17 cells. In mice, depletion of functional Tregs during late gestation induces preterm birth and adverse neonatal outcomes, which are rescued by the adoptive transfer of such cells. Treg depletion does not alter obstetrical parameters in the mother, yet it increases susceptibility to endotoxin-induced preterm birth. The mechanisms whereby depletion of Tregs induces adverse perinatal outcomes involve tissue-specific immune responses and mild systemic maternal inflammation, together with dysregulation of developmental and cellular processes in the placenta, in the absence of intra-amniotic inflammation. These findings provide mechanistic evidence supporting a role for Tregs in the pathophysiology of idiopathic preterm labor/birth and adverse neonatal outcomes.

Intra-Amniotic Infection with Ureaplasma parvum Causes Preterm Birth and Neonatal Mortality That Are Prevented by Treatment with Clarithromycin

Preterm birth is the leading cause of neonatal morbidity and mortality worldwide. Multiple etiologies are associated with preterm birth; however, 25% of preterm infants are born to a mother with intra-amniotic infection, most commonly due to invasion of the amniotic cavity by Ureaplasma species. Much research has focused on establishing a link between Ureaplasma species and adverse pregnancy/neonatal outcomes; however, little is known about the taxonomy of and host response against Ureaplasma species. Here, we applied a multifaceted approach, including human samples, in vivo models, and in vitro manipulations, to study the maternal-fetal immunobiology of Ureaplasma infection during pregnancy. Furthermore, we investigated the use of clarithromycin as a treatment for this infection. Our research provides translational knowledge that bolsters scientific understanding of Ureaplasma species as a cause of adverse pregnancy/neonatal outcomes and gives strong evidence for the use of clarithromycin as the recommended treatment for women intra-amniotically infected with Ureaplasma species.

Intra-amniotic infection is strongly associated with adverse pregnancy and neonatal outcomes. Most intra-amniotic infections are due to Ureaplasma species; however, the pathogenic potency of these genital mycoplasmas to induce preterm birth is still controversial. Here, we first laid out a taxonomic characterization of Ureaplasma isolates from women with intra-amniotic infection, which revealed that Ureaplasma parvum is the most common bacterium found in this clinical condition. Next, using animal models, we provided a causal link between intra-amniotic inoculation with Ureaplasma species and preterm birth. Importantly, the intra-amniotic inoculation of Ureaplasma species induced high rates of mortality in both preterm and term neonates. The in vivo potency of U. parvum to induce preterm birth was not associated with known virulence factors. However, term-derived and preterm-derived U. parvum isolates were capable of inducing an intra-amniotic inflammatory response. Both U. parvum isolates invaded several fetal tissues, primarily the fetal lung, and caused fetal inflammatory response syndrome. This bacterium was also detected in the placenta, reproductive tissues, and most severely in the fetal membranes, inducing a local inflammatory response that was replicated in an in vitro model. Importantly, treatment with clarithromycin, a recently recommended yet not widely utilized antibiotic, prevented the adverse pregnancy and neonatal outcomes induced by U. parvum. These findings shed light on the maternal-fetal immunobiology of intra-amniotic infection.

Maternal Obesity and the Uterine Immune Cell Landscape: The Shaping Role of Inflammation

Inflammation is often equated to the physiological response to injury or infection. Inflammatory responses defined by cytokine storms control cellular mechanisms that can either resolve quickly (i.e., acute inflammation) or remain prolonged and unabated (i.e., chronic inflammation). Perhaps less well-appreciated is the importance of inflammatory processes central to healthy pregnancy, including implantation, early stages of placentation, and parturition. Pregnancy juxtaposed with disease can lead to the perpetuation of aberrant inflammation that likely contributes to or potentiates maternal morbidity and poor fetal outcome. Maternal obesity, a prevalent condition within women of reproductive age, associates with increased risk of developing multiple pregnancy disorders. Importantly, chronic low-grade inflammation is thought to underlie the development of obesity-related obstetric and perinatal complications. While diverse subsets of uterine immune cells play central roles in initiating and maintaining healthy pregnancy, uterine leukocyte dysfunction as a result of maternal obesity may underpin the development of pregnancy disorders. In this review we discuss the current knowledge related to the impact of maternal obesity and obesity-associated inflammation on uterine immune cell function, utero-placental establishment, and pregnancy health.

Antibiotics, Inflammation, and Preterm Labor: A Missed Conclusion

Regarding the risk of antibiotic therapy during pregnancy, any medication given to the mother should be according to the indications due to the risk of possible side effects. Antibiotics are one of the most important groups of these medications to be considered. Along with direct antibiotic-induced side effects, indirect pathways also affect the fetus through the maternal changes. According to the data, different cytokines including interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) are involved in both term and preterm parturition. These cytokines could trigger expression of different substances such as prostaglandins (PGs), their receptors, and PGs synthetizing molecules with already proven roles in parturition. Moreover, IL-1, IL-6, and TNF-α knocked-out mice have delayed parturition and lower levels of PGs compared to the wild types. The earlier-mentioned cytokines are able to induce matrix metalloproteinases and are also involved in parturition. Certain antibiotics have been shown capable of inducing inflammation cascade directly. Both in-vivo and in-vitro studies in human have also demonstrated this inflammation as elevated levels of inflammatory cytokines especially IL-1, IL-6, and TNF-α. This increase has been observed both in the presence and the absence of lipopolysaccharide (LPS). Moreover, antibiotics can induce endotoxemia in healthy cases which finally leads to the pro-inflammatory cytokine release. Regarding the role of mentioned pro-inflammatory cytokines in both term and preterm parturition, it seems that non-indicated use of antibiotics during pregnancy may increase the risk of preterm labor.

Inflammasomes: Their Role in Normal and Complicated Pregnancies

Inflammasomes are cytoplasmic multiprotein complexes that coordinate inflammatory responses, including those that take place during pregnancy. Inflammasomes and their downstream mediators caspase-1 and IL-1β are expressed by gestational tissues (e.g., the placenta and chorioamniotic membranes) during normal pregnancy. Yet, only the activation of the NLRP3 inflammasome in the chorioamniotic membranes has been partially implicated in the sterile inflammatory process of term parturition. In vivo and ex vivo studies have consistently shown that the activation of the NLRP3 inflammasome is a mechanism whereby preterm labor and birth occur in the context of microbial- or alarmin-induced inflammation. In the placenta, the activation of the NLRP3 inflammasome is involved in the pathogenesis of preeclampsia and other pregnancy syndromes associated with placental inflammation. This evidence suggests that inhibition of the NLRP3 inflammasome or its downstream mediators may foster the development of novel anti-inflammatory therapies for the prevention or treatment of pregnancy complications.

HSP70: an alarmin that does not induce high rates of preterm birth but does cause adverse neonatal outcomes

Objective: Preterm labor and birth are strongly associated with sterile intra-amniotic inflammation, a clinical condition that is proposed to be initiated by danger signals, or alarmins. The aim of this study was to investigate whether the intra-amniotic administration of the alarmin heat shock protein 70 (HSP70) induces preterm labor/birth and adverse neonatal outcomes.Methods: Pregnant mice received an intra-amniotic injection of 200 ng (n = 8), 400 ng (n = 6), 500 ng (n = 10), or 1 µg of HSP70 (n = 6). Control mice were injected with saline (n = 10). Following injection, the rates of preterm labor/birth and neonatal mortality were recorded. Neonatal weights at weeks 1, 2, and 3 were also recorded.Results: The intra-amniotic injection of 400 ng [late preterm birth 16.7 ± 16.7% (1/6)], 500 ng [early and late preterm birth 10 ± 10% (1/10) each], or 1 µg [early preterm birth 16.7 ± 16.7% (1/6)] of HSP70 induced low rates of preterm/birth. However, the intra-amniotic injection of 500 ng or 1 µg of HSP70 induced significantly higher rates of neonatal mortality compared to controls [saline 14.2% (10/74), 200 ng 9.8% (6/61), 400 ng 17.9% (9/45), 500 ng 28.8% (23/78), and 1 µg 21.4% (13/49)]. Neonates born to dams injected with 200, 500 ng, or 1 µg HSP70 were leaner than controls (p ≤ .05).Conclusion: Intra-amniotic administration of the alarmin HSP70 did not induce high rates of preterm labor/birth; yet, it did indeed result in adverse neonatal outcomes.

Pulmonary Consequences of Prenatal Inflammatory Exposures: Clinical Perspective and Review of Basic Immunological Mechanisms

Chorioamnionitis, a potentially serious inflammatory complication of pregnancy, is associated with the development of an inflammatory milieu within the amniotic fluid surrounding the developing fetus. When chorioamnionitis occurs, the fetal lung finds itself in the unique position of being constantly exposed to the consequent inflammatory meditators and/or microbial products found in the amniotic fluid. This exposure results in significant changes to the fetal lung, such as increased leukocyte infiltration, altered cytokine, and surfactant production, and diminished alveolarization. These alterations can have potentially lasting impacts on lung development and function. However, studies to date have only begun to elucidate the association between such inflammatory exposures and lifelong consequences such as lung dysfunction. In this review, we discuss the pathogenesis of and fetal immune response to chorioamnionitis, detail the consequences of chorioamnionitis exposure on the developing fetal lung, highlighting the various animal models that have contributed to our current understanding and discuss the importance of fetal exposures in regard to the development of chronic respiratory disease. Finally, we focus on the clinical, basic, and therapeutic challenges in fetal inflammatory injury to the lung, and propose next steps and future directions to improve our therapeutic understanding of this important perinatal stress.

Fetal T Cell Activation in the Amniotic Cavity during Preterm Labor: A Potential Mechanism for a Subset of Idiopathic Preterm Birth

Prematurity is the leading cause of perinatal morbidity and mortality worldwide. In most cases, preterm birth is preceded by spontaneous preterm labor, a syndrome that is associated with intra-amniotic inflammation, the most studied etiology. However, the remaining etiologies of preterm labor are poorly understood; therefore, most preterm births are categorized as idiopathic. In this study, we provide evidence showing that the fetal immune system undergoes premature activation in women with preterm labor without intra-amniotic inflammation, providing a potential new mechanism of disease for some cases of idiopathic preterm birth. First, we showed that fetal T cells are a predominant leukocyte population in amniotic fluid during preterm gestations. Interestingly, only fetal CD4+ T cells were increased in amniotic fluid of women who underwent idiopathic preterm labor and birth. This increase in fetal CD4+ T cells was accompanied by elevated amniotic fluid concentrations of T cell cytokines such as IL-2, IL-4, and IL-13, which are produced by these cells upon in vitro stimulation, but was not associated with the prototypical cytokine profile observed in women with intra-amniotic inflammation. Also, we found that cord blood T cells, mainly CD4+ T cells, obtained from women with idiopathic preterm labor and birth displayed enhanced ex vivo activation, which is similar to that observed in women with intra-amniotic inflammation. Finally, we showed that the intra-amniotic administration of activated neonatal CD4+ T cells induces preterm birth in mice. Collectively, these findings provide evidence suggesting that fetal T cell activation is implicated in the pathogenesis of idiopathic preterm labor and birth.

Cellular immune responses in amniotic fluid of women with preterm labor and intra-amniotic infection or intra-amniotic inflammation

PROBLEM

Preterm birth is commonly preceded by preterm labor, a syndrome that is causally linked to both intra-amniotic infection and intra-amniotic inflammation. However, the stereotypical cellular immune responses in these two clinical conditions are poorly understood.

METHOD OF STUDY

Amniotic fluid samples (n = 26) were collected from women diagnosed with preterm labor and intra-amniotic infection (amniotic fluid IL-6 concentrations ≥2.6 ng/mL and culturable microorganisms, n = 10) or intra-amniotic inflammation (amniotic fluid IL-6 concentrations ≥2.6 ng/mL without culturable microorganisms, n = 16). Flow cytometry was performed to evaluate the phenotype and number of amniotic fluid leukocytes. Amniotic fluid concentrations of classical pro-inflammatory cytokines, type 1 and type 2 cytokines, and T-cell chemokines were determined using immunoassays.

RESULTS

Women with spontaneous preterm labor and intra-amniotic infection had (a) a greater number of total leukocytes, including neutrophils and monocytes/macrophages, in amniotic fluid; (b) a higher number of total T cells and CD4⁺ T cells, but not CD8⁺ T cells or B cells, in amniotic fluid; and (c) increased amniotic fluid concentrations of IL-6, IL-1β, and IL-10, compared to those with intra-amniotic inflammation. However, no differences in amniotic fluid concentrations of T-cell cytokines and chemokines were observed between these two clinical conditions.

CONCLUSION

The cellular immune responses observed in women with preterm labor and intra-amniotic infection are more severe than in those with intra-amniotic inflammation, and neutrophils, monocytes/macrophages, and CD4⁺ T cells are the main immune cells responding to microorganisms that invade the amniotic cavity. These findings provide insights into the intra-amniotic immune mechanisms underlying the human syndrome of preterm labor.

Antibiotic administration can eradicate intra-amniotic infection or intra-amniotic inflammation in a subset of patients with preterm labor and intact membranes

BACKGROUND

Intra-amniotic infection is present in 10% of patients with an episode of preterm labor, and is a risk factor for impending preterm delivery and neonatal morbidity/mortality. Intra-amniotic inflammation is often associated with intra-amniotic infection, but is sometimes present in the absence of detectable microorganisms. Antibiotic treatment of intra-amniotic infection has traditionally been considered to be ineffective. Intra-amniotic inflammation without microorganisms has a prognosis similar to that of intra-amniotic infection.

OBJECTIVE

To determine whether antibiotics can eradicate intra-amniotic infection or intra-amniotic inflammation in a subset of patients with preterm labor and intact membranes.

MATERIALS AND METHODS

The study population consisted of women who met the following criteria: 1) singleton gestation between 20 and 34 weeks; 2) preterm labor and intact membranes; 3) transabdominal amniocentesis performed for the evaluation of the microbiologic/inflammatory status of the amniotic cavity; 4) intra-amniotic infection and/or intra-amniotic inflammation; and 5) received antibiotic treatment that consisted of ceftriaxone, clarithromycin, and metronidazole. Follow-up amniocentesis was performed in a subset of patients. Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and polymerase chain reaction was performed for Ureaplasma spp. Intra-amniotic infection was defined as a positive amniotic fluid culture or positive polymerase chain reaction, and intra-amniotic inflammation was suspected when there was an elevated amniotic fluid white blood cell count or a positive result of a rapid test for matrix metalloproteinase-8. For this study, the final diagnosis of intra-amniotic inflammation was made by measuring the interleukin-6 concentration in stored amniotic fluid (>2.6 ng/mL). These results were not available to managing clinicians. Treatment success was defined as eradication of intra-amniotic infection and/or intra-amniotic inflammation or delivery ≥37 weeks.

RESULTS

Of 62 patients with intra-amniotic infection and/or intra-amniotic inflammation, 50 received the antibiotic regimen. Of those patients, 29 were undelivered for ≥7 days and 19 underwent a follow-up amniocentesis. Microorganisms were identified by culture or polymerase chain reaction of amniotic fluid obtained at admission in 21% of patients (4/19) who had a follow-up amniocentesis, and were eradicated in 3 of the 4 patients. Resolution of intra-amniotic infection/inflammation was confirmed in 79% of patients (15/19), and 1 other patient delivered at term, although resolution of intra-amniotic inflammation could not be confirmed after a follow-up amniocentesis. Thus, resolution of intra-amniotic inflammation/infection or term delivery (treatment success) occurred in 84% of patients (16/19) who had a follow-up amniocentesis. Treatment success occurred in 32% of patients (16/50) with intra-amniotic infection/inflammation who received antibiotics. The median amniocentesis-to-delivery interval was significantly longer among women who received the combination of antibiotics than among those who did not (11.4 days vs 3.1 days: P = .04).

CONCLUSION

Eradication of intra-amniotic infection/inflammation after treatment with antibiotics was confirmed in 79% of patients with preterm labor, intact membranes, and intra-amniotic infection/inflammation who had a follow-up amniocentesis. Treatment success occurred in 84% of patients who underwent a follow-up amniocentesis and in 32% of women who received the antibiotic regimen.

Visualization of microbes by 16S in situ hybridization in term and preterm placentas without intraamniotic infection

BACKGROUND

Numerous reports have documented bacteria in the placental membranes and basal plate decidua in the absence of immunopathology using histologic techniques. Similarly, independent metagenomic characterizations have identified an altered taxonomic makeup in association with spontaneous preterm birth. Here we sought to corroborate these findings by localizing presumptive intact bacteria using molecular histology within the placental microanatomy.

OBJECTIVE

Here we examined for microbes in term and preterm gestations using a signal-amplified 16S universal in situ hybridization probe set for bacterial rRNA, alongside traditional histologic methods of Warthin-Starry and Gram stains, as well as clinical culture methodologies. We further sought to differentiate accompanying 16S gene sequencing taxonomic profiles from germ-free (gnotobiotic) mouse and extraction and amplicon contamination controls.

STUDY DESIGN

Placentas were collected from a total of 53 subjects, composed of term labored (n = 4) and unlabored cesarean deliveries (n = 22) and preterm vaginal (n = 18) and cesarean deliveries (n = 8); a placenta from a single subject with clinical and histologic evident choriomanionitis was employed as a positive control (n = 1). The preterm cohort included spontaneous preterm birth with (n = 6) and without (n = 10) preterm premature rupture of membranes, as well as medically indicated preterm births (n = 10). Placental microbes were visualized using an in situ hybridization probe set designed against highly conserved regions of the bacterial 16S ribosome, which produces an amplified stable signal using branched DNA probes. Extracted bacterial nucleic acids from these same samples were subjected to 16S rRNA metagenomic sequencing (Illumina, V4) for course taxonomic analysis, alongside environmental and kit contaminant controls. A subset of unlabored, cesarean-delivered term pregnancies were also assessed with clinical culture for readily cultivatable pathogenic microbes.

RESULTS

Molecular in situ hybridization of bacterial rRNA enabled visualization and localization of low-abundance microbes after systematic high-power scanning. Despite the absence of clinical or histologic chorioamnionitis in 52 of 53 subjects, instances of 16S rRNA signal were confidently observed in 13 of 16 spontaneous preterm birth placentas, which was not significantly different from term unlabored cesarean specimens (18 of 22; P > .05). 16S rRNA signal was largely localized to the villous parenchyma and/or syncytiotrophoblast, and less commonly the chorion and the maternal intervillous space. In all term and unlabored cesarean deliveries, visualization of evident placental microbes by in situ hybridization occurred in the absence of clinical or histologic detection using conventional clinical cultivation, hematoxylin-eosin, and Gram staining. In 1 subject, appreciable villous bacteria localized to an infarction, where 16S microbial detection was confirmed by Warthin-Starry stain. In all instances, parallel sample principle coordinate analysis using Bray-Cutis distances of 16S rRNA gene sequencing data demonstrated consistent taxonomic distinction from all negative or potential contamination controls (P = .024, PERMANOVA). Classification from contaminant filtered data identified a distinct taxonomic makeup among term and preterm cohorts when compared with contaminant controls (false discovery rate <0.05).

CONCLUSION

Presumptively intact placental microbes are visualized as low-abundance, low-biomass and sparse populations within the placenta regardless of gestational age and mode of delivery. Their taxonomic makeup is distinct from contamination controls. These findings further support several previously published findings, including our own, which have used metagenomics to characterize low-abundance and low-biomass microbial communities in the placenta.

Evidence that antibiotic administration is effective in the treatment of a subset of patients with intra-amniotic infection/inflammation presenting with cervical insufficiency

BACKGROUND

Cervical insufficiency is a risk factor for spontaneous midtrimester abortion or early preterm birth. Intra-amniotic infection has been reported in 8-52% of such patients and intra-amniotic inflammation in 81%. Some professional organizations have recommended perioperative antibiotic treatment when emergency cervical cerclage is performed. The use of prophylactic antibiotics is predicated largely on the basis that they reduce the rate of complications during the course of vaginal surgery. However, it is possible that antibiotic administration can also eradicate intra-amniotic infection/inflammation and improve pregnancy outcome.

OBJECTIVE

To describe the outcome of antibiotic treatment in patients with cervical insufficiency and intra-amniotic infection/inflammation.

STUDY DESIGN

The study population consisted of 22 women who met the following criteria: (1) singleton pregnancy; (2) painless cervical dilatation of >1 cm between 16.0 and 27.9 weeks of gestation; (3) intact membranes and absence of uterine contractions; (4) transabdominal amniocentesis performed for the evaluation of the microbiologic and inflammatory status of the amniotic cavity; (5) presence of intra-amniotic infection/inflammation; and (6) antibiotic treatment (regimen consisted of ceftriaxone, clarithromycin, and metronidazole). Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and polymerase chain reaction for Ureaplasma spp. was performed. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms or a positive polymerase chain reaction for Ureaplasma spp., and intra-amniotic inflammation was suspected when there was an elevated amniotic fluid white blood cell count (≥19 cells/mm³) or a positive rapid test for metalloproteinase-8 (sensitivity 10 ng/mL). For the purpose of this study, the "gold standard" for diagnosis of intra-amniotic inflammation was an elevated interleukin-6 concentration (>2.6 ng/mL) using an enzyme-linked immunosorbent assay. The results of amniotic fluid interleukin-6 were not available to managing clinicians. Follow-up amniocentesis was routinely offered to monitor the microbiologic and inflammatory status of the amniotic cavity and fetal lung maturity. Treatment success was defined as resolution of intra-amniotic infection/inflammation or delivery ≥34 weeks of gestation.

RESULTS

Of 22 patients with cervical insufficiency and intra-amniotic infection/inflammation, 3 (14%) had microorganisms in the amniotic fluid. Of the 22 patients, 6 (27%) delivered within 1 week of amniocentesis and the remaining 16 (73%) delivered more than 1 week after the diagnostic procedure. Among these, 12 had a repeat amniocentesis to assess the microbial and inflammatory status of the amniotic cavity; in 75% (9/12), there was objective evidence of resolution of intra-amniotic inflammation or intra-amniotic infection demonstrated by analysis of amniotic fluid at the time of the repeat amniocentesis. Of the 4 patients who did not have a follow-up amniocentesis, all delivered ≥34 weeks, 2 of them at term; thus, treatment success occurred in 59% (13/22) of cases.

CONCLUSION

In patients with cervical insufficiency and intra-amniotic infection/inflammation, administration of antibiotics (ceftriaxone, clarithromycin, and metronidazole) was followed by resolution of the intra-amniotic inflammatory process or intra-amniotic infection in 75% of patients and was associated with treatment success in about 60% of cases.

Group B streptococcus activates transcriptomic pathways related to premature birth in human extraplacental membranes in vitro

Streptococcus agalactiae (group B streptococcus [GBS]) infection in pregnant women is the leading cause of infectious neonatal morbidity and mortality in the United States. Although inflammation during infection has been associated with preterm birth, the contribution of GBS to preterm birth is less certain. Moreover, the early mechanisms by which GBS interacts with the gestational tissue to affect adverse pregnancy outcomes are poorly understood. We hypothesized that short-term GBS inoculation activates pathways related to inflammation and premature birth in human extraplacental membranes. We tested this hypothesis using GBS-inoculated human extraplacental membranes in vitro. In agreement with our hypothesis, a microarray-based transcriptomics analysis of gene expression changes in GBS-inoculated membranes revealed that GBS activated pathways related to inflammation and preterm birth with significant gene expression changes occurring as early as 4 h postinoculation. In addition, pathways related to DNA replication and repair were downregulated with GBS treatment. Conclusions based on our transcriptomics data were further supported by responses of prostaglandin E2 (PGE2), and matrix metalloproteinases 1 (MMP1) and 3 (MMP3), all of which are known to be involved in parturition and premature rupture of membranes. These results support our initial hypothesis and provide new information on molecular targets of GBS infection in human extraplacental membranes.

A high concentration of fetal fibronectin in cervical secretions increases the risk of intra-amniotic infection and inflammation in patients with preterm labor and intact membranes

Objective To determine whether the risk of intra-amniotic infection/inflammation and spontaneous preterm delivery (SPTD) varies as a function of the concentration of cervical fetal fibronectin (fFN) in patients with preterm labor and intact membranes. Methods This prospective study included 180 patients with preterm labor and intact membranes who had a sample collected for quantitative fFN measurement and underwent amniocentesis. Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas. Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. Results (1) The prevalence of intra-amniotic infection/inflammation and SPTD within 7 days was 32.2% (58/180) and 33.9% (61/178), respectively; (2) The higher the fFN concentration, the greater the risk of intra-amniotic infection/inflammation and SPTD within 7 days (P<0.001, respectively); (3) An fFN concentration 150 ng/mL had a better diagnostic performance than an fFN 50 ng/mL in the identification of intra-amniotic infection/inflammation and SPTD within 7 days; (4) Among the patients with an fFN <50 ng/mL, intra-amniotic infection/inflammation was identified in 7.6% (6/79) of patients and 66.7% (4/6) delivered within 7 days. Conclusion The higher the concentration of fFN, the greater the risk of intra-amniotic infection/inflammation and SPTD in patients with preterm labor and intact membranes.

Are B cells altered in the decidua of women with preterm or term labor?

PROBLEM

The immunophenotype of B cells at the maternal-fetal interface (decidua) in labor at term and preterm labor is poorly understood.

METHOD OF STUDY

Decidual tissues were obtained from women with preterm or term labor and from non-labor gestational age-matched controls. Immunophenotyping of decidual B cells was performed using multicolor flow cytometry.

RESULTS

(a) In the absence of acute or chronic chorioamnionitis, total B cells were more abundant in the decidua parietalis of women who delivered preterm than in those who delivered at term, regardless of the presence of labor; (b) decidual transitional and naïve B cells were the most abundant B-cell subsets; (c) decidual B1 B cells were increased in women with either labor at term or preterm labor and chronic chorioamnionitis compared to those without this placental lesion; (d) decidual transitional B cells were reduced in women with preterm labor compared to those without labor; (e) naïve, class-switched, and non-class-switched B cells in the decidual tissues underwent mild alterations with the process of preterm labor; (f) decidual plasmablasts seemed to increase in women with either labor at term or preterm labor with chronic chorioamnionitis; and (g) decidual B cells expressed high levels of interleukin (IL)-12, IL-6, and/or IL-35.

CONCLUSION

Total B cells are not increased with the presence of preterm or term labor; yet, specific subsets (B1 and plasmablasts) undergo alterations in women with chronic chorioamnionitis. Therefore, B cells are solely implicated in the pathological process of preterm labor in a subset of women with chronic inflammation of the placenta. These findings provide insight into the immunology of the maternal-fetal interface in preterm and term labor.

Effector and Activated T Cells Induce Preterm Labor and Birth That Is Prevented by Treatment with Progesterone

Preterm labor commonly precedes preterm birth, the leading cause of perinatal morbidity and mortality worldwide. Most research has focused on establishing a causal link between innate immune activation and pathological inflammation leading to preterm labor and birth. However, the role of maternal effector/activated T cells in the pathogenesis of preterm labor/birth is poorly understood. In this study, we first demonstrated that effector memory and activated maternal T cells expressing granzyme B and perforin are enriched at the maternal-fetal interface (decidua) of women with spontaneous preterm labor. Next, using a murine model, we reported that prior to inducing preterm birth, in vivo T cell activation caused maternal hypothermia, bradycardia, systemic inflammation, cervical dilation, intra-amniotic inflammation, and fetal growth restriction, all of which are clinical signs associated with preterm labor. In vivo T cell activation also induced B cell cytokine responses, a proinflammatory macrophage polarization, and other inflammatory responses at the maternal-fetal interface and myometrium in the absence of an increased influx of neutrophils. Finally, we showed that treatment with progesterone can serve as a strategy to prevent preterm labor/birth and adverse neonatal outcomes by attenuating the proinflammatory responses at the maternal-fetal interface and cervix induced by T cell activation. Collectively, these findings provide mechanistic evidence showing that effector and activated T cells cause pathological inflammation at the maternal-fetal interface, in the mother, and in the fetus, inducing preterm labor and birth and adverse neonatal outcomes. Such adverse effects can be prevented by treatment with progesterone, a clinically approved strategy.

Does the human placenta delivered at term have a microbiota? Results of cultivation, quantitative real-time PCR, 16S rRNA gene sequencing, and metagenomics

BACKGROUND

The human placenta has been traditionally viewed as sterile, and microbial invasion of this organ has been associated with adverse pregnancy outcomes. Yet, recent studies that utilized sequencing techniques reported that the human placenta at term contains a unique microbiota. These conclusions are largely based on the results derived from the sequencing of placental samples. However, such an approach carries the risk of capturing background-contaminating DNA (from DNA extraction kits, polymerase chain reaction reagents, and laboratory environments) when low microbial biomass samples are studied.

OBJECTIVE

To determine whether the human placenta delivered at term in patients without labor who undergo cesarean delivery harbors a resident microbiota ("the assemblage of microorganisms present in a defined niche or environment").

STUDY DESIGN

This cross-sectional study included placentas from 29 women who had a cesarean delivery without labor at term. The study also included technical controls to account for potential background-contaminating DNA, inclusive in DNA extraction kits, polymerase chain reaction reagents, and laboratory environments. Bacterial profiles of placental tissues and background technical controls were characterized and compared with the use of bacterial culture, quantitative real-time polymerase chain reaction, 16S ribosomal RNA gene sequencing, and metagenomic surveys.

RESULTS

(1) Twenty-eight of 29 placental tissues had a negative culture for microorganisms. The microorganisms retrieved by culture from the remaining sample were likely contaminants because corresponding 16S ribosomal RNA genes were not detected in the same sample. (2) Quantitative real-time polymerase chain reaction did not indicate greater abundances of bacterial 16S ribosomal RNA genes in placental tissues than in technical controls. Therefore, there was no evidence of the presence of microorganisms above background contamination from reagents in the placentas. (3) 16S ribosomal RNA gene sequencing did not reveal consistent differences in the composition or structure of bacterial profiles between placental samples and background technical controls. (4) Most of the bacterial sequences obtained from metagenomic surveys of placental tissues were from cyanobacteria, aquatic bacteria, or plant pathogens, which are microbes unlikely to populate the human placenta. Coprobacillus, which constituted 30.5% of the bacterial sequences obtained through metagenomic sequencing of placental samples, was not identified in any of the 16S ribosomal RNA gene surveys of these samples. These observations cast doubt as to whether this organism is really present in the placenta of patients at term not in labor.

CONCLUSION

With the use of multiple modes of microbiologic inquiry, a resident microbiota could not be identified in human placentas delivered at term from women without labor. A consistently significant difference in the abundance and/or presence of a microbiota between placental tissue and background technical controls could not be found. All cultures of placental tissue, except 1, did not yield bacteria. Incorporating technical controls for potential sources of background-contaminating DNA for studies of low microbial biomass samples, such as the placenta, is necessary to derive reliable conclusions.