Intrauterine infection and prematurity

Indirect Effects of Neighbourhood Socioeconomic Status on Preterm Birth Risk in an Argentine Population

BACKGROUND

Preterm birth (PTB) is the main condition related to perinatal morbimortality worldwide. The aim of this study was to determine the indirect effects of neighbourhood socioeconomic status (NSES) on the risk of spontaneous PTB.

METHODS

We carried out a retrospective case-control study including sociodemographic and obstetric data of multigravid women who gave birth at a maternity hospital in Tucumán, Argentina, between 2005 and 2010: 949 women without previous PTB nor pregnancy loss who delivered at term and 552 who had spontaneous PTB. NSES was estimated from the Unsatisfied Basic Needs index of census data. Variables selected through penalised regressions were used to create a data-driven Bayesian network; then, pathways were identified and mediation analyses performed.

RESULTS

Maternal age less than 20 years mediated part of the protective effect of high NSES on spontaneous PTB [natural indirect effect (NIE) -0.0125, 95% confidence interval (CI) (-0.0208, -0.0041)] and on few prenatal visits (< 5) [NIE - 0.0095, 95% CI (-0.0166, -0.0025)]. These pathways showed greater sensitivity to unobserved confounders that affect the variables mediator-outcome in the same direction, and exposure-mediator in the opposite direction. They did not show sensitivity to observed potential confounders, nor to the parameterization used to define NSES. Meanwhile, urinary tract infections showed a trend in mediating the effect of low NSES on spontaneous PTB [NIE 0.0044, 95% CI (-0.0006, 0.0093), P 0.0834].

CONCLUSIONS

High NSES has protective indirect effects on spontaneous PTB risk, mainly associated with a lower frequency of teenage pregnancy.

Updates and Current Challenges in Reproductive Microbiome: A Comparative Analysis between Cows and Women

The microbiota plays an important role in numerous physiological processes, pathogenesis, development, and metabolism in different animal species. In humans, several studies have demonstrated an association between the vaginal microbiota and fertility rates, and even success in assisted reproduction techniques. In the context of cattle reproduction, although few studies have addressed the microbiota in a healthy state (which is not associated with diseases that affect the reproductive tract of cows), changes in its composition also seem to influence fertility. This review aims to explain the importance of the reproductive microbiota in female bovines and what is available in the literature regarding its possible role in increasing fertility. What are the challenges involved in this process? Future perspectives on its use and manipulation as a selection or intervention tool. Will it be possible to one day extrapolate the findings to reality and apply them in the field? In short, understanding the role of the reproductive microbiota of female bovines can signal the prospect of increasing production, whether of milk or meat, from the same number of animals, as it can optimize reproductive efficiency and perhaps become an allied tool for the economic profitability and sustainability of livestock farming.

Identification and characterization of plasma proteins associated with intra-amniotic inflammation and/or infection in women with preterm labor

This study aimed to identify plasma proteins that could serve as potential biomarkers for microbial invasion of the amniotic cavity (MIAC) or intra-amniotic inflammation (IAI) in women with preterm labor (PTL). A retrospective cohort comprised singleton pregnant women with PTL (24-34 weeks) who underwent amniocentesis. Pooled plasma samples were analyzed by label-free liquid chromatography-tandem mass spectrometry for proteome profiling in a nested case-control study (concomitant MIAC/IAI cases vs. non-MIAC/IAI controls [n = 10 per group]). Eight target proteins associated with MIAC/IAI were further verified by immunoassays in a large cohort (n = 230). Shotgun proteomic analysis revealed 133 differentially expressed proteins (fold change > 1.5, P < 0.05) in the plasma of MIAC/IAI cases. Further quantification confirmed that the levels of AFP were higher and those of kallistatin and TGFBI were lower in the plasma of women with MIAC and that the levels of kallistatin and TGFBI were lower in the plasma of women with IAI than in those without these conditions. The area under the curves of plasma AFP, kallistatin, and TGFBI ranged within 0.67-0.81 with respect to each endpoint. In summary, plasma AFP, kallistatin, and TGFBI may represent valuable non-invasive biomarkers for predicting MIAC or IAI in women with PTL.

Membrane inflammasome activation by choriodecidual Ureaplasma parvum infection without intra-amniotic infection in a Non-Human Primate model†

Intrauterine infection is a significant cause of neonatal morbidity and mortality. Ureaplasma parvum is a microorganism commonly isolated from cases of preterm birth and preterm premature rupture of membranes (pPROM). However, the mechanisms of early stage ascending reproductive tract infection remain poorly understood. To examine inflammation in fetal (chorioamnionic) membranes we utilized a non-human primate (NHP) model of choriodecidual U. parvum infection. Eight chronically catheterized pregnant rhesus macaques underwent maternal-fetal catheterization surgery at ~105-112 days gestation and choriodecidual inoculation with U. parvum (105 CFU/mL, n =4) or sterile media (controls; n = 4) starting at 115-119 days, repeated at 5-day intervals until C-section at 136-140 days (term=167 days). The average inoculation to delivery interval was 21 days, and Ureaplasma infection of the amniotic fluid (AF) was undetectable in all animals. Choriodecidual Ureaplasma infection resulted in increased fetal membrane expression of MMP-9 and PTGS2, but did not result in preterm labor or increased concentrations of AF pro-inflammatory cytokines. However, membrane expression of inflammasome sensors, NLRP3, NLRC4, AIM2, and NOD2, and adaptor ASC (PYCARD) gene expression were significantly increased. Gene expression of IL-1β, IL-18, IL-18R1  , CASPASE-1, and pro-CASPASE-1 protein increased with Ureaplasma infection. Downstream inflammatory genes MYD88 and NFκB (Nuclear factor kappa-light-chain-enhancer of activated B cells) were also significantly upregulated. These results demonstrate that choriodecidual Ureaplasma infection, can cause activation of inflammasome complexes and pathways associated with pPROM and preterm labor prior to microbes being detectable in the AF.

Measurements of Interleukin-8 and Matrix Metalloproteinases-9 in Cervicovaginal Fluid in Women with Preterm Labor: A Direct Comparison with Amniotic Fluid

OBJECTIVE

We aimed to evaluate the correlation and agreement of interleukin (IL)-8 and matrix metalloproteinases (MMP-9) levels between cervicovaginal (CVF) and amniotic fluids (AF) in women with preterm labor (PTL) and to determine the clinical values of these proteins in CVF compared with those in AF.

STUDY DESIGN

We designed a retrospective cohort study of 85 singleton pregnant women with PTL at 23 to 34 weeks, who underwent amniocentesis. The AF was cultured, and CVF samples were collected at the time of amniocentesis. Paired AF and CVF samples were assayed for IL-8 and MMP-9 by enzyme-linked immunoassay (ELISA) in duplicate on a single plate, using similar dilution ratios.

RESULTS

A significant but weak correlation was found for IL-8 levels between AF and CVF (r = 0.333), while no correlation was found for MMP-9 levels between AF and CVF (r = -0.039). Intra-class correlation coefficient for the agreement of IL-8 levels between CVF and AF was 0.4335 and -0.279 for MMP-9, indicating a poor-to-fair level of agreement between the two measured values, respectively. IL-8 and MMP-9 levels in CVF were not associated with the risk of either microbial invasion of the amniotic cavity (MIAC) or spontaneous preterm delivery (SPTD) within 7 days, whereas those in AF provided good-to-excellent predictive values for these two outcomes (area under the curve [AUCs]: 0.82-0.95). AUCs for IL-8 and MMP-9 were significantly larger using AF rather than using CVF for the prediction of MIAC and SPTD.

CONCLUSION

In women with PTL, IL-8 and MMP-9 levels in CVF do not precisely reflect the levels of the corresponding proteins in AF. IL-8 and MMP-9 levels in CVF had poor predictive values for the risk of MIAC and SPTD and were significantly inferior to those in AF.

KEY POINTS

· IL-8 and MMP-9 levels in CVF do not precisely reflect levels of the corresponding proteins in AF.. · Diagnostic accuracy of IL-8 and MMP-9 in CVF alone is not sufficient to predict MIAC and SPTD.. · IL-8 and MMP-9 levels in AF provide good-to-excellent predictive values for these two outcomes..

Neonatal sepsis and cardiovascular dysfunction I: mechanisms and pathophysiology

The highest incidence of sepsis across all age groups occurs in neonates leading to substantial mortality and morbidity. Cardiovascular dysfunction frequently complicates neonatal sepsis including biventricular systolic and/or diastolic dysfunction, vasoregulatory failure, and pulmonary arterial hypertension. The haemodynamic response in neonatal sepsis can be hyperdynamic or hypodynamic and the underlying pathophysiological mechanisms are heterogeneous. The diagnosis and definition of both neonatal sepsis and cardiovascular dysfunction complicating neonatal sepsis are challenging and not consensus-based. Future developments in neonatal sepsis management will be facilitated by common definitions and datasets especially in neonatal cardiovascular optimisation. IMPACT: Cardiovascular dysfunction is common in neonatal sepsis but there is no consensus-based definition, making calculating the incidence and designing clinical trials challenging. Neonatal cardiovascular dysfunction is related to the inflammatory response, which can directly target myocyte function and systemic haemodynamics.

Anaphylaxis-induced premature uterine contractions: a case report and literature review

BACKGROUND

Preterm labor is caused by multiple etiologies, including intra-amniotic infection and/or intra-amniotic inflammation, vascular disorders, cervical disease, decidual senescence, and breakdown of maternal-fetal tolerance. Accumulating evidence in vivo and in vitro has shown that an allergic reaction, including anaphylaxis, can induce preterm uterine contractions. This report describes a case of a pregnant woman who developed anaphylaxis and regular uterine contractions after the ingestion of a strawberry-coated biscuit. We also review the mechanism of allergic reaction (hypersensitivity)-induced preterm labor. Case presentation A 31-year-old woman (gravida 1, para 0) at 30+2 weeks of gestation was admitted to the labor and delivery unit with regular uterine contractions and anaphylactic symptoms after she ingested a strawberry-coated biscuit as a snack. The uterine contractions resolved after the treatment of anaphylaxis by administering antihistamines and epinephrine. The patient subsequently delivered at 39+3 weeks of gestation. The amniotic fluid profile showed no infection or inflammation. A postpartum skin-prick test confirmed a positive type 1 hypersensitivity reaction to the strawberry-coated biscuit.

CONCLUSIONS

We report a case of anaphylaxis-induced uterine contractility in which uterine contractions subsided after the treatment of anaphylaxis. The absence of intra-amniotic infection and/or intra-amniotic inflammation and the cause of the anaphylaxis were confirmed. Our findings indicate that maternal allergic reactions may be one of the mechanisms of preterm labor.

In premature rupture of membranes, maternal serum delta neutrophil index may be a predictive factor for histological chorioamnionitis and affect fetal inflammatory markers: A retrospective cross-sectional study

PROBLEM

We aimed to investigate the predictive value of delta neutrophil index (DNI) for histological choriomanionitis (HCAM) and the effect of maternal inflammatory markers on neonatal outcomes and fetal inflammatory parameters.

METHOD OF STUDY

In this retrospective cross-sectional study, 68 pregnant women without HCAM (group 1) and 46 pregnant women diagnosed with HCAM (group 2) were divided into two groups. Demographic stories of the groups; maternal hematological parameters; maternal DNI and systemic inflammatory index (SII) values; outcomes of newborns; fetal inflammatory markers were recorded and compared between groups.

RESULTS

Maternal DNI, and SII levels were significantly higher in group 2 (p value < .05 for all). Admission to the neonatal unit (NICU) was higher in group 2 than in group 1 (p = .0001). We found that fetal inflammatory markers were significantly higher in group 2 (p values .001 for CRP, .0001 for DNI, and .002 for leukocyte). Maternal DNI was determined to be significantly diagnostic at a value of ≥1.3 in HCAM (p = .001). We observed that SII had a significant predictive value of 953036.6 (p = .019) for NICU admission. There is also a positive correlation between fetal inflammatory markers and maternal inflammatory markers.

CONCLUSIONS

We found that maternal inflammatory markers are high in HCAM, maternal DNI can predict patients who will develop HCAM, maternal SII value can predict NICU admission, fetal inflammatory markers are high in HCAM, and these markers are affected by maternal inflammatory markers.

Blockade of IL-6R prevents preterm birth and adverse neonatal outcomes

BACKGROUND

Preterm birth preceded by spontaneous preterm labour often occurs in the clinical setting of sterile intra-amniotic inflammation (SIAI), a condition that currently lacks treatment.

METHODS

Proteomic and scRNA-seq human data were analysed to evaluate the role of IL-6 and IL-1α in SIAI. A C57BL/6 murine model of SIAI-induced preterm birth was developed by the ultrasound-guided intra-amniotic injection of IL-1α. The blockade of IL-6R by using an aIL-6R was tested as prenatal treatment for preterm birth and adverse neonatal outcomes. QUEST-MRI evaluated brain oxidative stress in utero. Targeted transcriptomic profiling assessed maternal, foetal, and neonatal inflammation. Neonatal biometrics and neurodevelopment were tested. The neonatal gut immune-microbiome was evaluated using metagenomic sequencing and immunophenotyping.

FINDINGS

IL-6 plays a critical role in the human intra-amniotic inflammatory response, which is associated with elevated concentrations of the alarmin IL-1α. Intra-amniotic injection of IL-1α resembles SIAI, inducing preterm birth (7% vs. 50%, p = 0.03, Fisher's exact test) and neonatal mortality (18% vs. 56%, p = 0.02, Mann-Whitney U-test). QUEST-MRI revealed no foetal brain oxidative stress upon in utero IL-1α exposure (p > 0.05, mixed linear model). Prenatal treatment with aIL-6R abrogated IL-1α-induced preterm birth (50% vs. 7%, p = 0.03, Fisher's exact test) by dampening inflammatory processes associated with the common pathway of labour. Importantly, aIL-6R reduces neonatal mortality (56% vs. 22%, p = 0.03, Mann-Whitney U-test) by crossing from the mother to the amniotic cavity, dampening foetal organ inflammation and improving growth. Beneficial effects of prenatal IL-6R blockade carried over to neonatal life, improving survival, growth, neurodevelopment, and gut immune homeostasis.

INTERPRETATION

IL-6R blockade can serve as a strategy to treat SIAI, preventing preterm birth and adverse neonatal outcomes.

FUNDING

NICHD/NIH/DHHS, Contract HHSN275201300006C. WSU Perinatal Initiative in Maternal, Perinatal and Child Health.

Evidence for the participation of CHCHD2/MNRR1, a mitochondrial protein, in spontaneous labor at term and in preterm labor with intra-amniotic infection

OBJECTIVE

Intra-amniotic inflammation (IAI), associated with either microbe (infection) or danger signals (sterile), plays a major role in the pathophysiology of preterm labor and delivery. Coiled-Coil-Helix-Coiled-Coil-Helix Domain Containing 2 (CHCHD2) [also known as Mitochondrial Nuclear Retrograde Regulator 1 (MNRR1)], a mitochondrial protein involved in oxidative phosphorylation and cell survival, is capable of sensing tissue hypoxia and inflammatory signaling. The ability to maintain an appropriate energy balance at the cellular level while adapting to environmental stress is essential for the survival of an organism. Mitochondrial dysfunction has been observed in acute systemic inflammatory conditions, such as sepsis, and is proposed to be involved in sepsis-induced multi-organ failure. The purpose of this study was to determine the amniotic fluid concentrations of CHCHD2/MNRR1 in pregnant women, women at term in labor, and those in preterm labor (PTL) with and without IAI.

METHODS

This cross-sectional study comprised patients allocated to the following groups: (1) mid-trimester (n = 16); (2) term in labor (n = 37); (3) term not in labor (n = 22); (4) PTL without IAI who delivered at term (n = 25); (5) PTL without IAI who delivered preterm (n = 47); and (6) PTL with IAI who delivered preterm (n = 53). Diagnosis of IAI (amniotic fluid interleukin-6 concentration ≥2.6 ng/mL) included cases associated with microbial invasion of the amniotic cavity and those of sterile nature (absence of detectable bacteria, using culture and molecular microbiology techniques). Amniotic fluid and maternal plasma CHCHD2/MNRR1 concentrations were determined with a validated and sensitive immunoassay.

RESULTS

(1) CHCHD2/MNRR1 was detectable in all amniotic fluid samples and women at term without labor had a higher amniotic fluid CHCHD2/MNRR1 concentration than those in the mid-trimester (p = 0.003); (2) the amniotic fluid concentration of CHCHD2/MNRR1 in women at term in labor was higher than that in women at term without labor (p = 0.01); (3) women with PTL and IAI had a higher amniotic fluid CHCHD2/MNRR1 concentration than those without IAI, either with preterm (p < 0.001) or term delivery (p = 0.01); (4) women with microbial-associated IAI had a higher amniotic fluid CHCHD2/MNRR1 concentration than those with sterile IAI (p < 0.001); (5) among women with PTL and IAI, the amniotic fluid concentration of CHCHD2/MNRR1 correlated with that of interleukin-6 (Spearman's Rho = 0.7; p < 0.001); and (6) no correlation was observed between amniotic fluid and maternal plasma CHCHD2/MNRR1 concentrations among women with PTL.

CONCLUSION

CHCHD2/MNRR1 is a physiological constituent of human amniotic fluid in normal pregnancy, and the amniotic concentration of this mitochondrial protein increases during pregnancy, labor at term, and preterm labor with intra-amniotic infection. Hence, CHCHD2/MNRR1 may be released into the amniotic cavity by dysfunctional mitochondria during microbial-associated IAI.

Membrane Inflammasome Activation by Choriodecidual Ureaplasma parvum Infection without Intra-Amniotic Infection in an NHP Model

Intrauterine infection is a significant cause of preterm labor and neonatal morbidity and mortality. Ureaplasma parvum is the micro-organism most commonly isolated from cases of preterm birth and preterm premature rupture of membranes (pPROM). However, the mechanisms during the early stages of ascending reproductive tract infection that initiate maternal-fetal inflammatory pathways, preterm birth and pPROM remain poorly understood. To examine inflammation in fetal (chorioamnionic) membranes in response to Ureaplasma parvum infection, we utilized a novel in vivo non-human primate model of early choriodecidual infection. Eight chronically catheterized pregnant rhesus macaques underwent maternal-fetal catheterization surgery at 105-112 days gestation and choriodecidual inoculation with Ureaplasma parvum (10 5 cfu/mL of a low passaged clinical isolate, serovar 1; n=4) or saline/sterile media (Controls; n=4) starting at 115-119 days gestation, repeated every 5 days until scheduled cesarean-section at 136-140d gestation (term=167d). The average inoculation to delivery interval was 21 days and Ureaplasma infection of the amniotic fluid was undetectable by culture and PCR in all animals. Inflammatory mediators in amniotic fluid (AF) were assessed by Luminex, ELISA and multiplex assays. RNA was extracted from the chorion and amnionic membranes for single gene analysis (qRT-PCR) and protein expression was determined by Western blot and immunohistochemistry. Our NHP model of choriodecidual Ureaplasma infection, representing an early-stage ascending reproductive tract infection without microbial invasion of the amniotic cavity, resulted in increased fetal membrane protein and gene expression of MMP-9 and PTGS2, but did not result in preterm labor (no increase in uterine contractility) or increased concentrations of amniotic fluid pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-18, TNF-α). However, membrane expression of inflammasome sensor molecules, NLRP3, NLRC4, AIM2 and NOD2, and the adaptor protein ASC ( PYCARD ) gene expression were significantly increased in the Ureaplasma group when compared to non-infected controls. Gene expression of IL-1 β, IL-18, the IL-18R1 receptor , CASPASE-1 and pro-CASPASE-1 protein were also increased in the fetal membranes with Ureaplasma infection. Downstream inflammatory signaling genes MYD88 was also significantly upregulated in both the amnion and chorion, along with a significant increase in NFKB in the chorion. These results demonstrate that even at the early stages of ascending reproductive tract Ureaplasma infection, activation of inflammasome complexes and pathways associated with degradation of chorioamnionic membrane integrity are present. This study therefore provides experimental evidence for the importance of the early stages of ascending Ureaplasma infection in initiating processes of pPROM and preterm labor. These findings have implications for the identification of intrauterine inflammation before microbes are detectable in the amniotic fluid (sterile inflammation) and the timing of potential treatments for preterm labor and fetal injury caused by intrauterine infection.

A Novel Predictive Machine Learning Model Integrating Cytokines in Cervical-Vaginal Mucus Increases the Prediction Rate for Preterm Birth

Preterm birth (PB) is a leading cause of perinatal morbidity and mortality. PB prediction is performed by measuring cervical length, with a detection rate of around 70%. Although it is known that a cytokine-mediated inflammatory process is involved in the pathophysiology of PB, none screening method implemented in clinical practice includes cytokine levels as a predictor variable. Here, we quantified cytokines in cervical-vaginal mucus of pregnant women (18-23.6 weeks of gestation) with high or low risk for PB determined by cervical length, also collecting relevant obstetric information. IL-2, IL-6, IFN-γ, IL-4, and IL-10 were significantly higher in the high-risk group, while IL-1ra was lower. Two different models for PB prediction were created using the Random Forest machine-learning algorithm: a full model with 12 clinical variables and cytokine values and the adjusted model, including the most relevant variables-maternal age, IL-2, and cervical length- (detection rate 66 vs. 87%, false positive rate 12 vs. 3.33%, false negative rate 28 vs. 6.66%, and area under the curve 0.722 vs. 0.875, respectively). The adjusted model that incorporate cytokines showed a detection rate eight points higher than the gold standard calculator, which may allow us to identify the risk PB risk more accurately and implement strategies for preventive interventions.

Extracellular Vesicles-mediated recombinant IL-10 protects against ascending infection-associated preterm birth by reducing fetal inflammatory response

Background

Fetal inflammatory response mediated by the influx of immune cells and activation of pro-inflammatory transcription factor NF-κB in feto-maternal uterine tissues is the major determinant of infection-associated preterm birth (PTB, live births < 37 weeks of gestation).

Objective

To reduce the incidence of PTB by minimizing inflammation, extracellular vesicles (EVs) were electroporetically engineered to contain anti-inflammatory cytokine interleukin (IL)-10 (eIL-10), and their efficacy was tested in an ascending model of infection (vaginal administration of E. coli) induced PTB in mouse models.

Study design

EVs (size: 30-170 nm) derived from HEK293T cells were electroporated with recombinant IL-10 at 500 volts and 125 Ω, and 6 pulses to generate eIL-10. eIL-10 structural characters (electron microscopy, nanoparticle tracking analysis, ExoView [size and cargo content] and functional properties (co-treatment of macrophage cells with LPS and eIL-10) were assessed. To test efficacy, CD1 mice were vaginally inoculated with E. coli (1010CFU) and subsequently treated with either PBS, eIL-10 (500ng) or Gentamicin (10mg/kg) or a combination of eIL-10+gentamicin. Fetal inflammatory response in maternal and fetal tissues after the infection or treatment were conducted by suspension Cytometer Time of Flight (CyTOF) using a transgenic mouse model that express red fluorescent TdTomato (mT+) in fetal cells.

Results

Engineered EVs were structurally and functionally stable and showed reduced proinflammatory cytokine production from LPS challenged macrophage cells in vitro. Maternal administration of eIL-10 (10 µg/kg body weight) crossed feto-maternal barriers to delay E. coli-induced PTB to deliver live pups at term. Delay in PTB was associated with reduced feto-maternal uterine inflammation (immune cell infiltration and histologic chorioamnionitis, NF-κB activation, and proinflammatory cytokine production).

Conclusions

eIL-10 administration was safe, stable, specific, delayed PTB by over 72 hrs and delivered live pups. The delivery of drugs using EVs overcomes the limitations of in-utero fetal interventions. Protecting IL-10 in EVs eliminates the need for the amniotic administration of recombinant IL-10 for its efficacy.

Intrauterine colonization with Gardnerella vaginalis and Mobiluncus mulieris induces maternal inflammation but not preterm birth in a mouse model

PROBLEM

Preterm birth (PTB) remains a leading cause of childhood mortality. Recent studies demonstrate that the risk of spontaneous PTB (sPTB) is increased in individuals with Lactobacillus-deficient vaginal microbial communities. One proposed mechanism is that vaginal microbes ascend through the cervix, colonize the uterus, and activate inflammatory pathways leading to sPTB. This study assessed whether intrauterine colonization with either Gardnerella vaginalis and Mobiluncus mulieris alone is sufficient to induce maternal-fetal inflammation and induce sPTB.

METHOD OF STUDY

C56/B6J mice, on embryonic day 15, received intrauterine inoculation of saline or 108 colony-forming units of G. vaginalis (n = 30), M. mulieris (n = 17), or Lactobacillus crispatus (n = 16). Dams were either monitored for maternal morbidity and sPTB or sacrificed 6 h post-infusion for analysis of bacterial growth and cytokine/chemokine expression in maternal and fetal tissues.

RESULTS

Six hours following intrauterine inoculation with G. vaginalis, M. mulieris, or L. crispatus, live bacteria were observed in both blood and amniotic fluid, and a potent immune response was identified in the uterus and maternal serum. In contrast, only a limited immune response was identified in the amniotic fluid and the fetus after intrauterine inoculation. High bacterial load (108 CFU/animal) of G. vaginalis was associated with maternal morbidity and mortality but not sPTB. Intrauterine infusion with L. crispatus or M. mulieris at 108 CFU/animal did not induce sPTB, alter pup viability, litter size, or maternal mortality.

CONCLUSIONS

Despite inducing an immune response, intrauterine infusion of live G. vaginalis or M. mulieris is not sufficient to induce sPTB in our mouse model. These results suggest that ascension of common vaginal microbes into the uterine cavity alone is not causative for sPTB.

Genomic analysis of Enterococcus faecium strain RAOG174 associated with acute chorioamnionitis carried antibiotic resistance gene: is it time for precise microbiological identification for appropriate antibiotic use?

BACKGROUND

Preterm labor syndrome is associated with high perinatal morbidity and mortality, and intra-amniotic infection is a cause of preterm labor. The standard identification of causative microorganisms is based on the use of biochemical phenotypes, together with broth dilution-based antibiotic susceptibility from organisms grown in culture. However, such methods could not provide an accurate epidemiological aspect and a genetic basis of antimicrobial resistance leading to an inappropriate antibiotic administration. Hybrid genome assembly is a combination of short- and long-read sequencing, which provides better genomic resolution and completeness for genotypic identification and characterization. Herein, we performed a hybrid whole genome assembly sequencing of a pathogen associated with acute histologic chorioamnionitis in women presenting with PPROM.

RESULTS

We identified Enterococcus faecium, namely E. faecium strain RAOG174, with several antibiotic resistance genes, including vancomycin and aminoglycoside. Virulence-associated genes and potential bacteriophage were also identified in this genome.

CONCLUSION

We report herein the first study demonstrating the use of hybrid genome assembly and genomic analysis to identify E. faecium ST17 as a pathogen associated with acute histologic chorioamnionitis. The analysis provided several antibiotic resistance-associated genes/mutations and mobile genetic elements. The occurrence of E. faecium ST17 raised the awareness of the colonization of clinically relevant E. faecium and the carrying of antibiotic resistance. This finding has brought the advantages of genomic approach in the identification of the bacterial species and antibiotic resistance gene for E. faecium for appropriate antibiotic use to improve maternal and neonatal care.

Gestational Viral Infections: Role of Host Immune System

Viral infections in pregnancy are major causes of maternal and fetal morbidity and mortality. Infections can develop in the neonate transplacentally, perinatally, or postnatally (from breast milk or other sources) and lead to different clinical manifestations, depending on the viral agent and the gestational age at exposure. Viewing the peculiar tolerogenic status which characterizes pregnancy, viruses could exploit this peculiar immunological status to spread or affect the maternal immune system, adopting several evasion strategies. In fact, both DNA and RNA virus might have a deep impact on both innate and acquired immune systems. For this reason, investigating the interaction with these pathogens and the host's immune system during pregnancy is crucial not only for the development of most effective therapies and diagnosis but mostly for prevention. In this review, we will analyze some of the most important DNA and RNA viruses related to gestational infections.

Proteomic analysis of plasma to identify novel biomarkers for intra-amniotic infection and/or inflammation in preterm premature rupture of membranes

To identify potential plasma biomarkers associated with microbial invasion of the amniotic cavity (MIAC) and/or intraamniotic inflammation (IAI) in women with preterm premature rupture of membranes (PPROM). This retrospective cohort study included 182 singleton pregnant women with PPROM (23-33 weeks) who underwent amniocentesis. Plasma samples; all subjects were chosen from these participants and were analyzed using label-free liquid chromatography-tandem mass spectrometry for proteome profiling using a nested case-control study design (cases with MIAC/IAI vs. non-MIAC/IAI controls [n = 9 each]). Three identified target molecules for MIAC/IAI were further verified by ELISA in the study cohort (n = 182). Shotgun proteomic analysis revealed 17 differentially expressed proteins (P < 0.05) in the plasma of MIAC/IAI cases. In particular, the levels of FCGR3A and haptoglobin, but not LRP1, were found to be increased in the plasma of patients with MIAC, IAI, and both MIAC/IAI compared with those without these conditions. Moreover, these differences remained significant after adjusting for gestational age at sampling. The area under the curves of plasma FCGR3A and haptoglobin ranged within 0.59-0.65 with respect to each of the three outcome measures. Plasma FCGR3A and haptoglobin were identified as potential independent biomarkers for less-invasively detecting MIAC/IAI in women with PPROM.

Roles of TGF-β1 in Viral Infection during Pregnancy: Research Update and Perspectives

Transforming growth factor-beta 1 (TGF-β1) is a pleiotropic growth factor playing various roles in the human body including cell growth and development. More functions of TGF-β1 have been discovered, especially its roles in viral infection. TGF-β1 is abundant at the maternal-fetal interface during pregnancy and plays an important function in immune tolerance, an essential key factor for pregnancy success. It plays some critical roles in viral infection in pregnancy, such as its effects on the infection and replication of human cytomegalovirus in syncytiotrophoblasts. Interestingly, its role in the enhancement of Zika virus (ZIKV) infection and replication in first-trimester trophoblasts has recently been reported. The above up-to-date findings have opened one of the promising approaches to studying the mechanisms of viral infection during pregnancy with links to corresponding congenital syndromes. In this article, we review our current and recent advances in understanding the roles of TGF-β1 in viral infection. Our discussion focuses on viral infection during pregnancy, especially in the first trimester. We highlight the mutual roles of viral infection and TGF-β1 in specific contexts and possible functions of the Smad pathway in viral infection, with a special note on ZIKV infection. In addition, we discuss promising approaches to performing further studies on this topic.

A single-cell atlas of murine reproductive tissues during preterm labor

Preterm birth, the leading cause of perinatal morbidity and mortality worldwide, frequently results from the syndrome of preterm labor. The best-established causal link to preterm labor is intra-amniotic infection, which involves premature activation of the parturition cascade in the reproductive tissues. Herein, we utilize single-cell RNA sequencing (scRNA-seq) to generate a single-cell atlas of the murine uterus, decidua, and cervix in a model of infection-induced preterm labor. We show that preterm labor affects the transcriptomic profiles of specific immune and non-immune cell subsets. Shared and tissue-specific gene expression signatures are identified among affected cells. Determination of intercellular communications implicates specific cell types in preterm labor-associated signaling pathways across tissues. In silico comparison of murine and human uterine cell-cell interactions reveals conserved signaling pathways implicated in labor. Thus, our scRNA-seq data provide insights into the preterm labor-driven cellular landscape and communications in reproductive tissues.

Maternal microbe-specific modulation of the offspring microbiome and development during pregnancy and lactation

The maternal microbiome is essential for the healthy growth and development of offspring and has long-term effects later in life. Recent advances indicate that the maternal microbiome begins to regulate fetal health and development during pregnancy. Furthermore, the maternal microbiome continues to affect early microbial colonization via birth and breastfeeding. Compelling evidence indicates that the maternal microbiome is involved in the regulation of immune and brain development and affects the risk of related diseases. Modulating offspring development by maternal diet and probiotic intervention during pregnancy and breastfeeding could be a promising therapy in the future. In this review, we summarize and discuss the current understanding of maternal microbiota development, perinatal microbial metabolite transfer, mother-to-infant microbial transmission during/after birth and its association with immune and brain development as well as corresponding diseases.

A Prospective Study of Mid-Trimester MCP-1 Levels as a Predictor of Preterm Delivery

Background: The prevention of preterm delivery (PTD) represents one of the major topics in modern obstetrics. The aim was to design a prospective study and investigate if mid-trimester serum and amniotic fluid levels of MCP-1 could predict the occurence of spontaneous PTD. Methods: The study involved 198 women who underwent genetic amniocentesis and blood sampling in the middle of their trimester. After applying the criteria for inclusion in the study, there were 16 respondents in the study group, and 38 respondents in the control group. Level of MCP-1 in amniotic fluid and serum was measured with commercially available enzyme-linked immunosorbent assays (ELISA) and statistical analysis was conducted. Results: There was no statistically significant difference in serum or amniotic fluid MCP1 levels between PTD and the control groups. Conclusion: The results suggest that MCP-1 is probably not the most relevant marker for predicting PTD. This study provides new normative data for MCP-1 levels in amniotic fluid and maternal sera and is a valuable tool for future diagnostic and comparative studies.

Preterm labor with intact membranes: a simple noninvasive method to identify patients at risk for intra-amniotic infection and/or inflammation

OBJECTIVE

To develop a noninvasive scoring system to identify patients at high risk for intra-amniotic infection and/or inflammation, which would reduce the need for amniocentesis.

METHODS

This prospective cohort study comprised patients admitted with preterm labor and intact membranes (20-34 weeks of gestation) who underwent a transabdominal amniocentesis and for whom concentrations of quantitative cervical fetal fibronectin and of maternal serum C-reactive protein (CRP) were determined. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms. Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. Multivariate logistic regression analysis was performed to identify intra-amniotic infection/inflammtion with noninvasive parameters that had a significant relationship with univariate analysis. With four parameters identified by multivariate analysis, we generated a noninvasive risk scoring system.

RESULTS

Of the study population consisting of 138 singleton pregnant women, (1) the overall rate of intra-amniotic infection/inflammation was 28.3% (39/138); (2) four parameters were used to develop a noninvasive risk scoring system [i.e. cervical fetal fibronectin concentration (score 0-2), maternal serum CRP concentration (score 0-2), cervical dilatation (score 0-2), and gestational age at presentation (score 0-1)]; the total score ranges from 0 to 7; 3) the area under the curve of the risk score was 0.96 (95% confidence interval (CI), 0.92-0.99), significantly higher than that of each predictor in the identification of intra-amniotic infection/inflammation (p < .001, for all); 4) the risk score with a cutoff of 4 had a sensitivity of 94.9% (37/39), a specificity of 90.9% (90/99), a positive predictive value of 80.4% (37/46), a negative predictive value of 97.8% (90/92), a positive likelihood ratio of 10.4 (95% CI, 5.6-19.5), and a negative likelihood ratio of 0.06 (95% CI, 0.15-0.22) in the identification of intra-amniotic infection/inflammation.

CONCLUSIONS

(1) The combination of four parameters (concentrations of cervical fetal fibronectin and maternal serum CRP, cervical dilatation, and gestational age) was independently associated with intra-amniotic infection and/or inflammation; and (2) the risk scoring system comprised of the combination of 4 noninvasive parameters was sensitive and specific to identify the patients at risk for intra-amniotic infection and/or inflammation.

Oral cleaning habits and the copy number of periodontal bacteria in pregnant women and its correlation with birth outcomes: an epidemiological study in Mibilizi, Rwanda

BACKGROUND

Since 1996, many studies have reported that periodontal disease during pregnancy may be a risk factor for preterm birth and low birth weight; however, in Africa, periodontal disease is considered a non-high-priority disease. In addition, there are few dental facilities in rural Rwanda; thus, the oral condition of pregnant women has not been investigated. The objective of this study was to assess the tooth brushing habits of pregnant women in rural Rwanda and evaluate whether periodontal bacteria in the oral cavity of pregnant women are related to birth outcomes or oral cleaning habits.

METHODS

A questionnaire survey and saliva collection were conducted for pregnant women in the catchment area population of Mibilizi Hospital located in the western part of Rwanda. Real-time PCR was performed to quantitatively detect total bacteria and 4 species of periodontal bacteria. The relationship of the copy number of each bacterium and birth outcomes or oral cleaning habits was statistically analyzed.

RESULTS

Among the participants, high copy numbers of total bacteria, Tannerella forsythia, and Treponema denticola were correlated with lower birth weight (p = 0.0032, 0.0212, 0.0288, respectively). The sex ratio at birth was higher in women who had high copy numbers of Porphyromonas gingivalis and T. denticola during pregnancy (p = 0.0268, 0.0043). Furthermore, regarding the correlation between oral cleaning habits and the amount of bacteria, the more frequently teeth were brushed, the lower the level of P. gingivalis (p = 0.0061); the more frequently the brush was replaced, the lower the levels of P. gingivalis and T. forsythia (p = 0.0153, 0.0029).

CONCLUSIONS

This study suggested that improving tooth brushing habits may reduce the risk of periodontal disease among pregnant women in rural Rwanda. It also indicated that the amount of bacteria is associated with various birth outcomes according to the bacterial species. Both access to dental clinics and the oral cleaning habits of pregnant women should be important considerations in efforts to alleviate reproductive-related outcomes in rural Africa.

Preterm Labor and Preterm-PROM at a Lower Gestational Age Are Associated with a Longer Latency-to-Delivery Even in Patients with the Same Intensity of Intra-Amniotic Inflammation: "Carroll-Model" Revisited

A previous study by Carroll et al. demonstrated that the time from preterm-PROM to delivery was longer at a lower gestational age (GA) when the membranes rupture, although the presence or absence of intra-amniotic inflammation (IAI) was not examined in that study. However, patients with either preterm labor (PTL) or preterm-PROM at a lower GA had more frequent IAI, which was associated with a shorter amniocentesis-to-delivery (ATD) interval as compared with inflammation-free amniotic fluid (AF). Up to now, there is no information about whether PTL and preterm-PROM at a lower GA are associated with a shorter or longer latency to delivery in cases with the same intensity of IAI. The objective of the study is to examine this issue. AF MMP-8 was measured in 476 singleton early preterm-gestations (21.5 < GA at amniocentesis < 34 wks) with PTL (n = 253) and preterm-PROM (n = 223). Patients were divided into three groups according to GA at amniocentesis (i.e., group-1: <26 wks; group-2: 26−30 wks; group-3: 30−34 wks). IAI was defined as an elevated AF MMP-8 (≥23 ng/mL), and IAI was classified into either mild IAI (AF MMP-8: 23−350 ng/mL) or severe IAI (AF MMP-8 ≥ 350 ng/mL). ATD interval was examined according to GA at amniocentesis in the context of the same intensity of IAI (i.e., inflammation-free AF, mild IAI, and severe IAI) among pregnant women with either PTL or preterm-PROM. IAI was more frequent at a lower GA in cases with PTL (group-1 vs. group-2 vs. group-3; 59.5% vs. 47.4% vs. 25.1%; X2test, p = 0.000034 and linear by linear association [LBLA], p = 0.000008) and in those with preterm-PROM (group-1 vs. group-2 vs. group-3; 69.2% vs. 50.0% vs. 32.0%; X2test, p = 0.000104, and LBLA, p = 0.000019). Of note, cases without IAI at a lower GA had a longer ATD interval in both PTL (Spearman’s rank correlation test, γ = −0.360, p = 0.000003) and preterm-PROM (γ = −0.570, p = 0.000001) groups. Moreover, the lower the GA, the longer the ATD interval, even among patients with mild and severe IAI in both PTL (Spearman’s rank correlation test; mild IAI, γ = −0.290, p = 0.039; severe IAI, γ = −0.299, p = 0.048) and preterm-PROM (mild IAI, γ = −0.565, p = 0.000013; severe IAI, γ = −0.363, p = 0.015) groups. In conclusion, PTL and preterm-PROM at a lower GA are associated with a longer latency to delivery, even in patients with the same intensity of IAI. This finding suggests that a more intense IAI may be needed for spontaneous preterm birth at a lower GA.

Genes, exposures, and interactions on preterm birth risk: an exploratory study in an Argentine population

Preterm birth (PTB) is the main condition related to perinatal morbimortality worldwide. The aim of this study was to identify associations of spontaneous PTB with genetic variants, exposures, and interactions between and within them. We carried out a retrospective case-control study including parental sociodemographic and obstetric data, and fetal genetic variants. We sequenced the coding and flanking regions of five candidate genes from the placental blood cord of 69 preterm newborns and 61 at term newborns. We identify the characteristics with the greatest predictive power of PTB using penalized regressions, in which we include exposures (E), genetic variants (G), and two-way interactions. Few prenatal visits (< 5) was the main predictor of PTB from 26 G, 35 E, 299 G × G, 564 E × E, and 875 G × E evaluated terms. Within the fetal genetic characteristics, we observed associations of rs4845397 (KCNN3, allele T) variant; G × G interaction between rs12621551 (COL4A3, allele T) and rs73993878 (COL4A3, allele A), which showed sensitivity to anemia; and G × G interaction between rs11680670 (COL4A3, allele T) and rs2074351 (PON1, allele A), which showed sensitivity to vaginal discharge. The results of this exploratory study suggest that social disparities and metabolic pathways linked to uterine relaxation, inflammation/infections, and collagen metabolism would be involved in PTB etiology. Future studies with a larger sample size are necessary to confirm these findings and to analyze a greater number of exposures.

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.

Preterm birth etiological pathways: a Bayesian networks and mediation analysis approach

BACKGROUND

The aim of this study was to determine the mediating effect of spontaneous preterm birth (PTB) main predictors that would allow to suggest etiological pathways.

METHODS

We carried out a case-control study, including sociodemographic characteristics, habits, health care, and obstetric data of multiparous women who gave birth at a maternity hospital from Tucumán, Argentina, between 2005 and 2010: 998 women without previous PTB who delivered at term and 562 who delivered preterm. We selected factors with the greatest predictive power using a penalized logistic regression model. A data-driven Bayesian network including the selected factors was created where we identified pathways and performed mediation analyses.

RESULTS

We identified three PTB pathways whose natural indirect effect was greater than zero with a 95% confidence interval: maternal age less than 20 years mediated by few prenatal visits, vaginal bleeding in the first trimester mediated by vaginal bleeding in the second trimester, and urinary tract infection mediated by vaginal bleeding in the second trimester. The effect mediated in these pathways showed greater sensitivity to confounders affecting the variables mediator-outcome and exposure-mediator in the same direction.

CONCLUSION

The identified pathways suggest PTB etiological lines related to social disparities and exposure to genitourinary tract infections.

IMPACT

Few prenatal visits (<5) and vaginal bleeding are two of the main predictors for spontaneous preterm birth in the studied population. Few prenatal visits mediates part of the risk associated with maternal age less than 20 years and vaginal bleeding in the second trimester mediates part of the risk associated with vaginal bleeding in the first trimester and with urinary tract infection. Social disparities and exposure to genitourinary tract infections would be etiological lines of spontaneous preterm birth.

Respiratory responses to hypoxia during rest and exercise in individuals born pre-term: a state-of-the-art review

The pre-term birth survival rate has increased considerably in recent decades, and research investigating the long-term effects of premature birth is growing. Moreover, altitude sojourns are increasing in popularity and are often accompanied by various levels of physical activity. Individuals born pre-term appear to exhibit altered acute ventilatory responses to hypoxia, potentially predisposing them to high-altitude illness. These impairments are likely due to the use of perinatal hyperoxia stunting the maturation of carotid body chemoreceptors, but may also be attributed to limited lung diffusion capacity and/or gas exchange inefficiency. Aerobic exercise capacity also appears to be reduced in this population. This may relate to the aforementioned respiratory impairments, or could be due to physiological limitations in pulmonary blood flow or at the exercising muscle (e.g. mitochondrial efficiency). However, surprisingly, the debilitative effects of exercise when performed at altitude do not seem to be exacerbated by premature birth. In fact, it is reasonable to speculate that pre-term birth could protect against the consequences of exercise combined with hypoxia. The mechanisms that underlie this assertion might relate to differences in oxidative stress responses or in cardiopulmonary morphology in pre-term individuals, compared to their full-term counterparts. Further research is required to elucidate the independent effects of neonatal treatment, sex differences and chronic lung disease, and to establish causality in some of the proposed mechanisms that could underlie the differences discussed throughout this review. A more in-depth understanding of the acclimatisation responses to chronic altitude exposures would also help to inform appropriate interventions in this clinical population.

Comprehensive human amniotic fluid metagenomics supports the sterile womb hypothesis

As metagenomic approaches for detecting infectious agents have improved, each tissue that was once thought to be sterile has been found to harbor a variety of microorganisms. Controversy still exists over the status of amniotic fluid, which is part of an immunologically privileged zone that is required to prevent maternal immune system rejection of the fetus. Due to this privilege, the exclusion of microbes has been proposed to be mandatory, leading to the sterile womb hypothesis. Since nucleic acid yields from amniotic fluid are very low, contaminating nucleic acid found in water, reagents and the laboratory environment frequently confound attempts to address this hypothesis. Here we present metagenomic criteria for microorganism detection and a metagenomic method able to be performed with small volumes of starting material, while controlling for exogenous contamination, to circumvent these and other pitfalls. We use this method to show that human mid-gestational amniotic fluid has no detectable virome or microbiome, supporting the sterile womb hypothesis.

Gut Microbiota and Metabolome Description of Antibiotic-Treated Neonates From Parturients With Intrauterine Infection

Intrauterine infection is linked to adverse pregnancy outcomes in pregnant women. Neonates from parturients with intrauterine infection are usually treated with antibiotics, but their gut microbiota and metabolome are seldom studied. In this study, we collected fecal samples from antibiotic-treated neonates of parturients with intrauterine infection (intrauterine infection group), parturients with non-intrauterine infection (antibiotic group), and untreated neonates of healthy parturients (control group). 16S rRNA gene sequencing and untargeted metabolomics analyses were performed. Our results revealed that the α-diversity of intrauterine infection group differed from that of control group. There were significant differences in β-diversity between intrauterine infection group and control group, between antibiotic group and the control group, but there was no difference between the intrauterine infection and antibiotic groups, implying that antibiotic use has an obvious effect on β-diversity and that the effects of intrauterine infection on β-diversity cannot be identified. Enterococcus was more abundant in intrauterine infection and antibiotic groups than in control group. Gut metabolite differences in intrauterine infection group and antibiotic group (only in negative ion mode) from control group were observed, but no difference between intrauterine infection group and antibiotic group was observed. N-formyl-L-methionine was the most discriminant metabolite between intrauterine infection group and control group. Primary and secondary bile acid biosynthesis, bile secretion, and cholesterol metabolism pathways were altered, and the abundances of bile acids and bile salts were altered in intrauterine infection group compared with control group. Alterations in cholesterol metabolism, arginine biosynthesis and bile secretion pathways were observed both in intrauterine infection and antibiotic groups, which might be caused by the use of antibiotics. In conclusion, we provided a preliminary description of the gut microbiota and gut metabolites in antibiotics-treated neonates from intrauterine infection parturients. Our findings did not show intrauterine infection has a separate role in neonatal gut microbiota dysbiosis, while supporting the idea that antibiotics should be used with caution during neonatal therapy.

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

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

Optimization and validation of two multiplex qPCR assays for the rapid detection of microorganisms commonly invading the amniotic cavity

Microbial invasion of the amniotic cavity (MIAC) leading to infection is strongly associated with adverse pregnancy and neonatal outcomes. Limitations of current diagnostic assays to detect MIAC rapidly and accurately have hindered the ability of obstetricians to identify and treat intra-amniotic infections. We developed, optimized, and validated two multiplex quantitative polymerase chain reaction (qPCR) assays for the simultaneous detection and quantification of microbial taxa commonly associated with MIAC. The first assay allows for the quantification of general bacterial and fungal loads in amniotic fluid and includes a human reference gene to allow for assessing the integrity of clinical samples and the DNA extraction process. The second assay allows for the detection and quantification of four specific bacterial taxa commonly associated with MIAC: Ureaplasma spp., Mycoplasma hominis, Streptococcus agalactiae, and Fusobacterium nucleatum. The qPCR assays were validated by using both microbial isolates and clinical amniotic fluid samples. The assays were further validated by comparing qPCR amplification results to those from the microbial culture and bacterial 16S rRNA gene sequencing of amniotic fluid. Both assays demonstrated high reproducibility and are sensitive and specific to their intended targets. Therefore, these assays represent promising molecular diagnostic tools for the detection of MIAC. Most importantly, these assays may allow for administration of timely and targeted antibiotic interventions to reduce adverse perinatal outcomes attributed to intra-amniotic infections.

Human fetal membrane IL-1β production in response to bacterial components is mediated by uric-acid induced NLRP3 inflammasome activation

Inflammatory interleukin-1β (IL-1β) is an important mediator of preterm birth. IL-1β secretion is mediated by the inflammasome that processes pro-IL-1β into its active form. However the mechanisms involved at the level of the fetal membrane (FM) are not fully understood. This study sought to determine the FM compartment involved in IL-1β production in response to bacterial components and to evaluate the mechanism of inflammasome activation. Since IL-18 is also mediated by the inflammasome and IL-8 is a chemoattractant that contributes to neutrophil recruitment in chorioamnionitis, we also evaluated the production of these factors. A human explant system was used to evaluate the response of the chorion, amnion, and intact FMs to the bacterial components lipopolysaccharide (LPS), peptidoglycan (PGN), or muramyl dipeptide (MDP). The chorion was the major source of IL-1β and IL-8 production in response to LPS, PGN, and MDP. LPS, PGN, and MDP induced FM IL-1β and IL-18 secretion in a non-pyroptotic manner through activation of the NLRP3 inflammasome with contributions from ATP release through Pannexin-1, and ROS signaling. Since LPS, PGN, and MDP are not known to activate NLRP3 directly, the role of uric acid as a potential mediator was assessed. FMs produced elevated uric acid in response to LPS, PGN and MDP. FM IL-1β secretion was inhibited by allopurinol, which blocks uric acid production, for LPS and PGN, and to a lesser degree, MDP. These findings shed light on the mechanisms by which fetal membrane inflammation and subsequent preterm birth may arise.

Molecular mechanisms of environmental toxin cadmium at the feto-maternal interface investigated using an organ-on-chip (FMi-OOC) model

Human labor is associated with feto-maternal-derived signals that coordinate to initiate delivery. Exposure to environmental chemicals can prematurely trigger labor-initiating signals at the feto-maternal interface (FMi: decidua, amniochorion), leading to spontaneous preterm birth (PTB). Testing the association between environmental chemical exposure and PTB is difficult due to many limitations in vivo or in vitro. Physiological organ-on-chips (OOCs) are potential alternatives for studying mechanisms leading to PTB. The presented study tested the effect of maternal exposure to cadmium (Cd), an environmental toxin, using the FMi-OOC that incorporates maternal decidua cells and three different fetal cells (chorion, amnion mesenchymal, and amnion epithelial cells). Cd transport through the FMi and its impact on cell cycle, cell death, and inflammation were analyzed. Cd treatment resulted in significant cell death and a pro-inflammatory environment in the maternal decidua, but had minimal effect on the fetal chorion cells, and no effect in the fetal amnion cells compared to controls. The maternal response, but lack of fetal response, indicates that Cd-mediated adverse effects originate from maternal pathophysiology rather than fetal-derived triggers of preterm labor. This study demonstrates that the FMi-OOC can indeed predict the response of FMi upon exposure to chemicals, opening the possibility for using OOC models for environmental toxin screens.

A Broad-Spectrum Chemokine Inhibitor Blocks Inflammation-Induced Myometrial Myocyte-Macrophage Crosstalk and Myometrial Contraction

Prophylactic administration of the broad-spectrum chemokine inhibitor (BSCI) FX125L has been shown to suppress uterine contraction, prevent preterm birth (PTB) induced by Group B Streptococcus in nonhuman primates, and inhibit uterine cytokine/chemokine expression in a murine model of bacterial endotoxin (LPS)-induced PTB. This study aimed to determine the mechanism(s) of BSCI action on human myometrial smooth muscle cells. We hypothesized that BSCI prevents infection-induced contraction of uterine myocytes by inhibiting the secretion of pro-inflammatory cytokines, the expression of contraction-associated proteins and disruption of myocyte interaction with tissue macrophages. Myometrial biopsies and peripheral blood were collected from women at term (not in labour) undergoing an elective caesarean section. Myocytes were isolated and treated with LPS with/out BSCI; conditioned media was collected; cytokine secretion was analyzed by ELISA; and protein expression was detected by immunoblotting and immunocytochemistry. Functional gap junction formation was assessed by parachute assay. Collagen lattices were used to examine myocyte contraction with/out blood-derived macrophages and BSCI. We found that BSCI inhibited (1) LPS-induced activation of transcription factor NF-kB; (2) secretion of chemokines (MCP-1/CCL2 and IL-8/CXCL8); (3) Connexin43-mediated intercellular connectivity, thereby preventing myocyte–macrophage crosstalk; and (4) myocyte contraction. BSCI represents novel therapeutics for prevention of inflammation-induced PTB in women.

Development of a mouse model of ascending infection and preterm birth

BACKGROUND

Microbial invasion of the intraamniotic cavity and intraamniotic inflammation are factors associated with spontaneous preterm birth. Understanding the route and kinetics of infection, sites of colonization, and mechanisms of host inflammatory response is critical to reducing preterm birth risk.

OBJECTIVES

This study developed an animal model of ascending infection and preterm birth with live bacteria (E. coli) in pregnant CD-1 mice with the goal of better understanding the process of microbial invasion of the intraamniotic cavity and intraamniotic inflammation.

STUDY DESIGN

Multiple experiments were conducted in this study. To determine the dose of E. coli required to induce preterm birth, CD-1 mice were injected vaginally with four different doses of E. coli (103, 106, 1010, or 1011 colony forming units [CFU]) in 40 μL of nutrient broth or broth alone (control) on an embryonic day (E)15. Preterm birth (defined as delivery before E18.5) was monitored using live video. E. coli ascent kinetics were measured by staining the E. coli with lipophilic tracer DiD for visualization through intact tissue with an in vivo imaging system (IVIS) after inoculation. The E. coli were also directly visualized in reproductive tissues by staining the bacteria with carboxyfluorescein succinimidyl ester (CFSE) prior to administration and via immunohistochemistry (IHC) by staining tissues with anti-E. coli antibody. Each pup's amniotic fluid was cultured separately to determine the extent of microbial invasion of the intraamniotic cavity at different time points. Intraamniotic inflammation resulting from E. coli invasion was assessed with IHC for inflammatory markers (TLR-4, P-NF-κB) and neutrophil marker (Ly-6G) for chorioamnionitis at 6- and 24-h post-inoculation.

RESULTS

Vaginally administered E. coli resulted in preterm birth in a dose-dependent manner with higher doses causing earlier births. In ex vivo imaging and IHC detected uterine horns proximal to the cervix had increased E. coli compared to the distal uterine horns. E. coli were detected in the uterus, fetal membranes (FM), and placenta in a time-dependent manner with 6 hr having increased intensity of E. coli positive signals in pups near the cervix and in all pups at 24 hr. Similarly, E. coli grew from the cultures of amniotic fluid collected nearest to the cervix, but not from the more distal samples at 6 hr post-inoculation. At 24 hr, all amniotic fluid cultures regardless of distance from the cervix, were positive for E. coli. TLR-4 and P-NF-κB signals were more intense in the tissues where E. coli was present (placenta, FM and uterus), displaying a similar trend toward increased signal in proximal gestational sacs compared to distal at 6 hr. Ly-6G+ cells, used to confirm chorioamnionitis, were increased at 24 hr compared to 6 hr post-inoculation and control.

CONCLUSION

We report the development of mouse model of ascending infection and the associated inflammation of preterm birth. Clinically, these models can help to understand mechanisms of infection associated preterm birth, determine targets for intervention, or identify potential biomarkers that can predict a high-risk pregnancy status early in pregnancy.

Maternal Plasma and Amniotic Fluid LBP, Pentraxin 3, Resistin, and IGFBP-3: Biomarkers of Microbial Invasion of Amniotic Cavity and/or Intra-amniotic Inflammation in Women with Preterm Premature Rupture of Membranes

BACKGROUND

We sought to determine whether lipopolysaccharide binding protein (LBP), pentraxin 3, resistin, and insulin-like growth factor binding protein (IGFBP)-3 in plasma and amniotic fluid (AF) can predict microbial invasion of the amniotic cavity (MIAC), intra-amniotic inflammation (IAI), and microbial-associated IAI in women with preterm premature rupture of membranes (PPROM).

METHODS

This was a retrospective cohort study involving 168 singleton pregnant women with PPROM. AF obtained via amniocentesis was cultured and assayed for interleukin (IL)-6 to define IAI and for IL-8 to compare with AF biomarkers. Plasma samples were collected at the time of amniocentesis, and C-reactive protein (CRP) levels in serum were compared with plasma biomarkers. The stored plasma and AF samples were assayed for LBP, pentraxin 3 (PTX3), resistin, and IGFBP-3 by ELISA.

RESULTS

Multivariate logistic regression analysis revealed that: 1) elevated plasma and AF levels of LBP were independently associated with increased risks of MIAC, IAI, and microbial-associated IAI; 2) elevated AF, but not plasma, PTX3, and resistin levels were independently associated with increased risks of MIAC, IAI, and microbial-associated IAI; 3) decreased IGFBP-3 levels in the plasma were independently associated with only IAI, whereas those in the AF were associated with only microbial-associated IAI. Among the tested biomarkers, AF PTX3 and resistin had the highest predictive performance for MIAC, IAI, and microbial-associated IAI (area under the curves [AUC] = 0.85-0.95), which is similar to the performance of AF IL-8. The AUCs of the plasma LBP and IGFBP-3 were similar to that of serum CRP with respect to IAI.

CONCLUSION

Maternal plasma LBP and IGFBP-3 are potential biomarkers for the non-invasive identification of IAI in women with PPROM, with a similar accuracy to the serum CRP level. AF LBP, PTX3, resistin, and IGFBP-3 may be involved in the intra-amniotic inflammatory responses in PPROM complicated by MIAC.

Sustained peripheral immune hyper-reactivity (SPIHR): an enduring biomarker of altered inflammatory responses in adult rats after perinatal brain injury

Background

Chorioamnionitis (CHORIO) is a principal risk factor for preterm birth and is the most common pathological abnormality found in the placentae of preterm infants. CHORIO has a multitude of effects on the maternal–placental–fetal axis including profound inflammation. Cumulatively, these changes trigger injury in the developing immune and central nervous systems, thereby increasing susceptibility to chronic sequelae later in life. Despite this and reports of neural–immune changes in children with cerebral palsy, the extent and chronicity of the peripheral immune and neuroinflammatory changes secondary to CHORIO has not been fully characterized.

Methods

We examined the persistence and time course of peripheral immune hyper-reactivity in an established and translational model of perinatal brain injury (PBI) secondary to CHORIO. Pregnant Sprague–Dawley rats underwent laparotomy on embryonic day 18 (E18, preterm equivalent). Uterine arteries were occluded for 60 min, followed by intra-amniotic injection of lipopolysaccharide (LPS). Serum and peripheral blood mononuclear cells (PBMCs) were collected at young adult (postnatal day P60) and middle-aged equivalents (P120). Serum and PBMCs secretome chemokines and cytokines were assayed using multiplex electrochemiluminescent immunoassay. Multiparameter flow cytometry was performed to interrogate immune cell populations.

Results

Serum levels of interleukin-1β (IL-1β), IL-5, IL-6, C–X–C Motif Chemokine Ligand 1 (CXCL1), tumor necrosis factor-α (TNF-α), and C–C motif chemokine ligand 2/monocyte chemoattractant protein-1 (CCL2/MCP-1) were significantly higher in CHORIO animals compared to sham controls at P60. Notably, CHORIO PBMCs were primed. Specifically, they were hyper-reactive and secreted more inflammatory mediators both at baseline and when stimulated in vitro. While serum levels of cytokines normalized by P120, PBMCs remained primed, and hyper-reactive with a robust pro-inflammatory secretome concomitant with a persistent change in multiple T cell populations in CHORIO animals.

Conclusions

The data indicate that an in utero inflammatory insult leads to neural–immune changes that persist through adulthood, thereby conferring vulnerability to brain and immune system injury throughout the lifespan. This unique molecular and cellular immune signature including sustained peripheral immune hyper-reactivity (SPIHR) and immune cell priming may be a viable biomarker of altered inflammatory responses following in utero insults and advances our understanding of the neuroinflammatory cascade that leads to perinatal brain injury and later neurodevelopmental disorders, including cerebral palsy.

Role of Maternal Infections and Inflammatory Responses on Craniofacial Development

Pregnancy is a tightly regulated immunological state. Mild environmental perturbations can affect the developing fetus significantly. Infections can elicit severe immunological cascades in the mother's body as well as the developing fetus. Maternal infections and resulting inflammatory responses can mediate epigenetic changes in the fetal genome, depending on the developmental stage. The craniofacial development begins at the early stages of embryogenesis. In this review, we will discuss the immunology of pregnancy and its responsive mechanisms on maternal infections. Further, we will also discuss the epigenetic effects of pathogens, their metabolites and resulting inflammatory responses on the fetus with a special focus on craniofacial development. Understanding the pathophysiological mechanisms of infections and dysregulated inflammatory responses during prenatal development could provide better insights into the origins of craniofacial birth defects.

The Inflammatory Milieu of Amniotic Fluid Increases with Chorio-Deciduitis Grade in Inflammation-Restricted to Choriodecidua, but Not Amnionitis, of Extra-Placental Membranes

No information exists about whether intra-amniotic inflammatory response increases with a chorio-deciduitis grade in the context of both inflammation-restricted to chorio-decidua and amnionitis of extra-placental membranes among spontaneous preterm births. The objective of current study is to examine this issue. A study population included 195 singleton pregnant women with chorio-deciduitis, and who spontaneously delivered at preterm (21.6~35.7 weeks) within 7 days of amniocentesis. We examined intra-amniotic inflammatory response according to the chorio-deciduitis grade in the context of inflammation restricted to chorio-decidua and amnionitis of extra-placental membranes. Intra-amniotic inflammatory response was measured by MMP-8 concentration (ng/mL) and WBC-count (cells/mm3) in amniotic-fluid (AF). Inflammation restricted to chorio-decidua and amnionitis were present in 47.7% (93/195) and 52.3% (102/195) of cases, respectively. Median AF MMP-8 concentration and WBC-count significantly increased with chorio-deciduitis grade in the context of inflammation restricted to chorio-decidua. However, there was no significant difference in median AF MMP-8 concentration and WBC-count between chorio-deciduitis grade-1 and grade-2 in the context of amnionitis. The inflammatory milieu of AF increases with chorio-deciduitis grade in inflammation-restricted to chorio-decidua, but not amnionitis, of extra-placental membranes. This finding suggests that a chorio-deciduitis grade may have little effect on the intensification of intra-amniotic inflammatory response in the context of amnionitis of extra-placental membranes.

Acute chorioamnionitis and intra-amniotic inflammation are more severe according to outside-in neutrophil migration within the same chorio-decidua

OBJECTIVE

No information exists about whether acute histologic chorioamnionitis (acute-HCA) is more advanced and severe, and intra-amniotic inflammation is more frequent and intense according to outside in neutrophil migration within the same chorio-decidua. The objective of current study is to examine this issue.

MATERIALS AND METHODS

We included 106 singleton preterm-births (gestational age at delivery: 20-34 weeks) due to either preterm-labor or preterm-PROM in the context of acute chorio-deciduitis. Study-population was divided into 3 groups according to outside-in neutrophil migration within chorio-decidua as follows: 1) group-1: 'inflammation restricted to the decidua' (n = 22); 2) group-2: 'inflammation restricted to the MT of chorion and the decidua' (n = 31); 3) group-3: 'inflammation in the CT of chorion' (n = 53). We examined the frequency of inflammation in each placental compartment beyond chorio-decidua (i.e., amnion, umbilical cord, and chorionic-plate), and total grade (1-8) of acute-HCA. Moreover, the frequency of intra-amniotic infection (defined as positive amniotic-fluid culture for aerobic and anaerobic bacteria and genital mycoplasmas) and intra-amniotic inflammation (defined as amniotic fluid WBC ≥ 19 cells/mm³), and an intra-amniotic inflammatory response gauged by amnioticfluid WBC count (cells/mm³) were examined in 50 amniotic fluid samples within 7 days of birth.

RESULTS

Amnionitis, funisitis and chorionic plate inflammation were more frequent (each for P < 0.01) and median total grade of acute-HCA was increased (P < 0.001) according to outside-in neutrophil migration within chorio-decidua (group-1vs.group-2vs.group-3). Moreover, intra-amniotic infection and inflammation were more frequent (each-for P < 0.05) and median amniotic-fluid WBC count was increased (P < 0.01) according-to outside-in neutrophil-migration within chorio-decidua (group-1 vs. group-2 vs. group-3).

CONCLUSION

Acute-HCA is more advanced and severe, and intra-amniotic inflammation is more frequent and intense according to outside in neutrophil migration within the same chorio-decidua. This finding suggests that what is now acute chorio-deciduitis should be subdivided.

Periodontal Pathogens and Preterm Birth: Current Knowledge and Further Interventions

Preterm labor is defined as a birth before 37 weeks of gestation and occurs in 5–20% of pregnancies. Preterm labor, as multifactorial entity associated with a high risk of neonatal morbidity and mortality, is influenced by maternal, fetal and environmental factors. Microbiological studies suggest that infectious pathogens may account for 25–40% of preterm birth. Infections of different sites, like genital, urinary tract infections, and pneumonia, are linked to the preterm labor. The most recent epidemiological studies consistently report that maternal periodontal disease is associated with preterm delivery, as well as the association between the presence of pathogenic oral bacteria in the placenta and adverse pregnancy outcomes. On the other hand, some previously published papers found periodontal bacteria in placentas of term pregnancies. In spite of a huge research done on the topic, both experimental and clinical, there are many controversial opinions about the role of periodontal infections in preterm birth. Thus, this comprehensive review addresses this very important topic and evaluates novel strategies of preventive and therapeutic approaches.

Impact of TLR7 and TLR9 polymorphisms on susceptibility to placental infections and pregnancy complications

This study evaluated the impact of the TLR7 Gln11Leu (rs179008) and TLR9 -1237 T/C (rs5743836) single nucleotide polymorphisms (SNPs) on susceptibility to placental infections and pregnancy complications in 455 Brazilian women. Demographic, socioeconomic, gynecological, and clinical characteristics of the women were collected. Placental tissues were sampled from pregnant women and human and viral DNA was extracted. Human alphaherpesvirus 1 (Herpes simplex virus type 1, HSV-1), Human alphaherpesvirus 2 (Herpes simplex virus type 2, HSV-2) and Human betaherpesvirus 5 (Human cytomegalovirus, HCMV) were detected by nested PCR. TLR9 and TLR7 SNPs were genotyped by PCR amplification of bi-directional specific alleles (Bi-PASA) and restriction fragment length polymorphism (RFLP), respectively. Infections at the time of birth were detected in 45.71 % of women. The presence of the TT genotype (recessive model) of the TLR7 SNP was associated with increased susceptibility to HSV-1 infection (O.R. = 2.23, p = 0.05). The presence of the C allele of the TLR9 SNP, in heterozygosis or homozygosis (dominant model), decreased the infection risk by HCMV (O.R. = 0.31, p-mod<0.05). The TT genotype (recessive model) of the TLR7 SNP was significantly associated (p < 0.05) with increased occurrence of pre-treated hypertension. The codominant model of the TLR9 SNP was significantly associated (p < 0.05) with reduced risk of hospitalization during pregnancy. In combination, the AA/CT (TLR7-TLR9) genotypes significantly decreased the risk of placental infection by HSV-1 and/or HSV-2 (O.R. = 0.47, p = 0.02), the susceptibility to all infectious agents considered in combination (O.R. = 0.4, p = 0.00), and the need of hospitalization (O.R. = 0.48, p = 0.02). In conclusion, TLR7 and TLR9 SNPs are potential modulating factors for the risk of placental infections and pregnancy complications.

Utility of Routine Testing for Chlamydia and Gonorrhea in the Setting of Preterm Delivery or Premature Preterm Rupture of Membranes

This study aimed to explore the rates of positive and negative Chlamydia trachomatis and Neisseria gonorrhoeae test results in patients screened for these infections and later experienced preterm delivery or preterm premature rupture of membranes. The team conducted a retrospective chart review of patients admitted for preterm premature rupture of membranes or who experienced preterm delivery between April 1, 2009, and April 30, 2015. Patients lacking chlamydia and gonorrhea screening before admission were excluded from the study. Four hundred and six patients met the inclusion criteria. The prevalence of chlamydia infection at initial prenatal screening before admission was 13.3%. Among those for whom the prenatal chlamydia test was negative, 1.7% of patients had a positive subsequent chlamydia test on admission screening. Among those for whom the prenatal chlamydia test was positive, 18.5% had a positive subsequent chlamydia test on admission screening. Positive prenatal test (P=.002) and age 25 years or less (P<.001) were associated with positive admission screening for chlamydia, though only a positive prenatal test remained significant in a logistic regression model (odds ratio, 8.56; 95% CI, 2.67-27.49; P=.003). The prevalence of gonorrhea was low at 0.2% of patients positive for gonorrhea at prenatal testing and 0.5% of patients positive for gonorrhea at admission testing. Our results suggest that individualization based on patient characteristics may be utilized to decrease re-testing. More research is needed to identify possible additional risk factors for new infection or re-infection and the most optimal timing for re-screening during the prenatal period.

Antimicrobial Activity of Human Fetal Membranes: From Biological Function to Clinical Use

The fetal membranes provide a supportive environment for the growing embryo and later fetus. Due to their versatile properties, the use of fetal membranes in tissue engineering and regenerative medicine is increasing in recent years. Moreover, as microbial infections present a crucial complication in various treatments, their antimicrobial properties are gaining more attention. The antimicrobial peptides (AMPs) are secreted by cells from various perinatal derivatives, including human amnio-chorionic membrane (hACM), human amniotic membrane (hAM), and human chorionic membrane (hCM). By exhibiting antibacterial, antifungal, antiviral, and antiprotozoal activities and immunomodulatory activities, they contribute to ensuring a healthy pregnancy and preventing complications. Several research groups investigated the antimicrobial properties of hACM, hAM, and hCM and their derivatives. These studies advanced basic knowledge of antimicrobial properties of perinatal derivatives and also provided an important insight into the potential of utilizing their antimicrobial properties in a clinical setting. After surveying the studies presenting assays on antimicrobial activity of hACM, hAM, and hCM, we identified several considerations to be taken into account when planning future studies and eventual translation of fetal membranes and their derivatives as antimicrobial agents from bench to bedside. Namely, (1) the standardization of hACM, hAM, and hCM preparation to guarantee rigorous antimicrobial activity, (2) standardization of the antimicrobial susceptibility testing methods to enable comparison of results between various studies, (3) investigation of the antimicrobial properties of fetal membranes and their derivatives in the in vivo setting, and (4) designation of donor criteria that enable the optimal donor selection. By taking these considerations into account, future studies will provide crucial information that will enable reaching the optimal treatment outcomes using the fetal membranes and their derivatives as antimicrobial agents.

Fetal Growth Restriction and Subsequent Low Grade Fetal Inflammatory Response Are Associated with Early-Onset Neonatal Sepsis in the Context of Early Preterm Sterile Intrauterine Environment

There is no information about whether fetal growth restriction (FGR) is an independent risk factor for low-grade fetal inflammatory response (FIR), and which is more valuable for the prediction of early-onset neonatal sepsis (EONS) between low-grade FIR or fetal inflammatory response syndrome (FIRS) in the context of human early preterm sterile intrauterine environment. We examined FIR (umbilical cord plasma (UCP) CRP concentration at birth) according to the presence or absence of FGR (birth weight < 5th percentile for gestational age (GA)) and EONS in 81 singleton preterm births (GA at delivery: 24.5~33.5 weeks) within 72 h after amniocentesis and with sterile intrauterine environment. A sterile intrauterine environment was defined by the presence of both a sterile amniotic fluid (AF) (AF with both negative culture and MMP-8 < 23 ng/mL) and inflammation-free placenta. Median UCP CRP (ng/mL) was higher in cases with FGR than in those without FGR (63.2 vs. 34.5; p = 0.018), and FGR was an independent risk factor for low-grade FIR (UCP CRP ≥ 52.8 ng/mL) (OR 3.003, 95% CI 1.024-8.812, p = 0.045) after correction for confounders. Notably, low-grade FIR (positive likelihood-ratio (LR) and 95% CI, 2.3969 (1.4141-4.0625); negative-LR and 95% CI, 0.4802 (0.2591-0.8902)), but not FIRS (positive-LR and 95% CI, 2.1071 (0.7526-5.8993); negative-LR and 95% CI, 0.8510 (0.6497-1.1145)), was useful for the identification of EONS. In conclusion, FGR is an independent risk factor for low-grade FIR, and low-grade FIR, but not FIRS, has a value for the identification of EONS in the context of the early preterm sterile intrauterine environment.

Multiomics analysis reveals the presence of a microbiome in the gut of fetal lambs

OBJECTIVE

Microbial exposure is critical to neonatal and infant development, growth and immunity. However, whether a microbiome is present in the fetal gut prior to birth remains debated. In this study, lambs delivered by aseptic hysterectomy at full term were used as an animal model to investigate the presence of a microbiome in the prenatal gut using a multiomics approach.

DESIGN

Lambs were euthanised immediately after aseptic caesarean section and their cecal content and umbilical cord blood samples were aseptically acquired. Cecal content samples were assessed using metagenomic and metatranscriptomic sequencing to characterise any existing microbiome. Both sample types were analysed using metabolomics in order to detect microbial metabolites.

RESULTS

We detected a low-diversity and low-biomass microbiome in the prenatal fetal gut, which was mainly composed of bacteria belonging to the phyla Proteobacteria, Actinobacteria and Firmicutes. Escherichia coli was the most abundant species in the prenatal fetal gut. We also detected multiple microbial metabolites including short chain fatty acids, deoxynojirimycin, mitomycin and tobramycin, further indicating the presence of metabolically active microbiota. Additionally, bacteriophage phiX174 and Orf virus, as well as antibiotic resistance genes, were detected in the fetal gut, suggesting that bacteriophage, viruses and bacteria carrying antibiotic resistance genes can be transmitted from the mother to the fetus during the gestation period.

CONCLUSIONS

This study provides strong evidence that the prenatal gut harbours a microbiome and that microbial colonisation of the fetal gut commences in utero.

Nicotine induces maternal and fetal inflammatory responses which predispose intrauterine infection risk in a rat model

Introduction

Both smoking and infection adversely impact pregnancy. Previously, our group identified in a rodent model that 6 mg/kg/d nicotine increased the risk of fetal infection at gestation day (GD) 18. Here, we investigate lower nicotine doses.

Methods

Pregnant Sprague-Dawley rats received nicotine infusion at 0, 1, or 3 mg/kg/d (no, low-, and mid-dose nicotine, respectively) from GD 6, with intravenous inoculation with Mycoplasma pulmonis (MP) at 10⁷ CFU (N = 20) or sterile broth (sham) (N = 11) on GD 14. Uterus and fetuses were retrieved on GD 18 for MP culture and histopathologic evaluation of maternal and fetal inflammatory responses (MIR and FIR).

Results

At 1 mg/kg/d nicotine, MP colonization rates were decreased, from 100% (9 of 9) to 40% (2 of 5) of MP-inoculated dams (p = .03), and 59% (66 of 111) to 39% (24 of 62) of fetuses (p = .01), versus no nicotine. Low-dose nicotine resulted in increased MIR and FIR in the sham-inoculated group; in the MP-inoculated group, this resulted in reduced relative risk (RR) for placental colonization (RR, 95% CI with high MIR = 0.14, 0.02 to 0.65; FIR = 0.38, 0.12 to 0.93). In contrast, 3 mg/kg/d nicotine treatment did not alter colonization rates; furthermore, FIR was completely suppressed, even in the face of placental or amniotic fluid colonization.

Conclusion

The 1 mg/kg/d nicotine dose decreased risk of intrauterine infection, with increased MIR and FIR. The 3 mg/kg/d nicotine dose inhibited FIR, and increased risk for intrauterine infection. Nicotine alterations of the intrauterine environment were markedly dose-dependent.

Implications

Nicotine exposure alters intrauterine infection and inflammation in a dose-dependent manner, potentially impacting fetal development and programming. Previous work in a rodent model showed that high-dose nicotine (6 mg/kg/d) exposure exacerbated intrauterine infection during pregnancy. The current study found that low-dose nicotine (1 mg/kg/d) exposure reduced colonization of placenta and amniotic fluid; this decrease was associated with increased intrauterine inflammation. Exposure to mid-dose nicotine (3 mg/kg/d) suppressed fetal inflammation. Elucidation of underlying mechanisms of these phenomena will inform public health and clinical care decisions, particularly in the context of risk assessment of nicotine replacement therapy during pregnancy for smoking cessation.