Elucidating the early signal transduction pathways leading to fetal brain injury in preterm birth

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.

Intra-amniotic inflammation in the mid-trimester of pregnancy is a risk factor for neuropsychological disorders in childhood

OBJECTIVES

Intra-amniotic inflammation is a subclinical condition frequently caused by either microbial invasion of the amniotic cavity or sterile inflammatory stimuli, e.g., alarmins. An accumulating body of evidence supports a role for maternal immune activation in the genesis of fetal neuroinflammation and the occurrence of neurodevelopmental disorders such as cerebral palsy, schizophrenia, and autism. The objective of this study was to determine whether fetal exposure to mid-trimester intra-amniotic inflammation is associated with neurodevelopmental disorders in children eight to 12 years of age.

METHODS

This is a retrospective case-control study comprising 20 children with evidence of prenatal exposure to intra-amniotic inflammation in the mid-trimester and 20 controls matched for gestational age at amniocentesis and at delivery. Amniotic fluid samples were tested for concentrations of interleukin-6 and C-X-C motif chemokine ligand 10, for bacteria by culture and molecular microbiologic methods as well as by polymerase chain reaction for eight viruses. Neuropsychological testing of children, performed by two experienced psychologists, assessed cognitive and behavioral domains. Neuropsychological dysfunction was defined as the presence of an abnormal score (<2 standard deviations) on at least two cognitive tasks.

RESULTS

Neuropsychological dysfunction was present in 45% (9/20) of children exposed to intra-amniotic inflammation but in only 10% (2/20) of those in the control group (p=0.03). The relative risk (RR) of neuropsychological dysfunction conferred by amniotic fluid inflammation remained significant after adjusting for gestational age at delivery [aRR=4.5 (1.07-16.7)]. Of the 11 children diagnosed with neuropsychological dysfunction, nine were delivered at term and eight of them had mothers with intra-amniotic inflammation. Children exposed to intra-amniotic inflammation were found to have abnormalities in neuropsychological tasks evaluating complex skills, e.g., auditory attention, executive functions, and social skills, whereas the domains of reasoning, language, and memory were not affected in the cases and controls.

CONCLUSIONS

Asymptomatic sterile intra-amniotic inflammation in the mid-trimester of pregnancy, followed by a term birth, can still confer to the offspring a substantial risk for neurodevelopmental disorders in childhood. Early recognition and treatment of maternal immune activation in pregnancy may be a strategy for the prevention of subsequent neurodevelopmental disorders in offspring.

Intrauterine Inflammation Leads to Select Sex- and Age-Specific Behavior and Molecular Differences in Mice

Sex-specific differences in behavior have been observed in anxiety and learning in children exposed to prenatal inflammation; however, whether these behaviors manifest differently by age is unknown. This study assesses possible behavioral changes due to in utero inflammation as a function of age in neonatal, juvenile, and adult animals and presents potential molecular targets for observed differences. CD-1 timed pregnant dams were injected in utero with lipopolysaccharide (LPS, 50 μg/animal) or saline at embryonic day 15. No differences in stress responses were measured by neonatal ultrasonic vocalizations between LPS- and saline-exposed groups of either sex. By contrast, prenatal inflammation caused a male-specific increase in anxiety in mature but not juvenile animals. Juvenile LPS-exposed females had decreased movement in open field testing that was not present in adult animals. We additionally observed improved memory retrieval after in utero LPS in the juvenile animals of both sexes, which in males may be related to a perseverative phenotype. However, there was an impairment of long-term memory in only adult LPS-exposed females. Finally, gene expression analyses revealed that LPS induced sex-specific changes in genes involved in hippocampal neurogenesis. In conclusion, intrauterine inflammation has age- and sex-specific effects on anxiety and learning that may correlate to sex-specific disruption of gene expression associated with neurogenesis in the hippocampus.

Early Life Events and Maturation of the Dentate Gyrus: Implications for Neurons and Glial Cells

The dentate gyrus (DG), an important part of the hippocampus, plays a significant role in learning, memory, and emotional behavior. Factors potentially influencing normal development of neurons and glial cells in the DG during its maturation can exert long-lasting effects on brain functions. Early life stress may modify maturation of the DG and induce lifelong alterations in its structure and functioning, underlying brain pathologies in adults. In this paper, maturation of neurons and glial cells (microglia and astrocytes) and the effects of early life events on maturation processes in the DG have been comprehensively reviewed. Early postnatal interventions affecting the DG eventually result in an altered number of granule neurons in the DG, ectopic location of neurons and changes in adult neurogenesis. Adverse events in early life provoke proinflammatory changes in hippocampal glia at cellular and molecular levels immediately after stress exposure. Later, the cellular changes may disappear, though alterations in gene expression pattern persist. Additional stressful events later in life contribute to manifestation of glial changes and behavioral deficits. Alterations in the maturation of neuronal and glial cells induced by early life stress are interdependent and influence the development of neural nets, thus predisposing the brain to the development of cognitive and psychiatric disorders.

Animal Models of Chorioamnionitis: Considerations for Translational Medicine

Preterm birth is defined as any birth occurring before 37 completed weeks of gestation by the World Health Organization. Preterm birth is responsible for perinatal mortality and long-term neurological morbidity. Acute chorioamnionitis is observed in 70% of premature labor and is associated with a heavy burden of multiorgan morbidities in the offspring. Unfortunately, chorioamnionitis is still missing effective biomarkers and early placento- as well as feto-protective and curative treatments. This review summarizes recent advances in the understanding of the underlying mechanisms of chorioamnionitis and subsequent impacts on the pregnancy outcome, both during and beyond gestation. This review also describes relevant and current animal models of chorioamnionitis used to decipher associated mechanisms and develop much needed therapies. Improved knowledge of the pathophysiological mechanisms underpinning chorioamnionitis based on preclinical models is a mandatory step to identify early in utero diagnostic biomarkers and design novel anti-inflammatory interventions to improve both maternal and fetal outcomes.

IFNγ-Producing γ/δ T Cells Accumulate in the Fetal Brain Following Intrauterine Inflammation

Intrauterine inflammation impacts prenatal neurodevelopment and is linked to adverse neurobehavioral outcomes ranging from cerebral palsy to autism spectrum disorder. However, the mechanism by which a prenatal exposure to intrauterine inflammation contributes to life-long neurobehavioral consequences is unknown. To address this gap in knowledge, this study investigates how inflammation transverses across multiple anatomic compartments from the maternal reproductive tract to the fetal brain and what specific cell types in the fetal brain may cause long-term neuronal injury. Utilizing a well-established mouse model, we found that mid-gestation intrauterine inflammation resulted in a lasting neutrophil influx to the decidua in the absence of maternal systemic inflammation. Fetal immunologic changes were observed at 72-hours post-intrauterine inflammation, including elevated neutrophils and macrophages in the fetal liver, and increased granulocytes and activated microglia in the fetal brain. Through unbiased clustering, a population of Gr-1+ γ/δ T cells was identified as the earliest immune cell shift in the fetal brain of fetuses exposed to intrauterine inflammation and determined to be producing high levels of IFNγ when compared to γ/δ T cells in other compartments. In a case-control study of term infants, IFNγ was found to be elevated in the cord blood of term infants exposed to intrauterine inflammation compared to those without this exposure. Collectively, these data identify a novel cellular immune mechanism for fetal brain injury in the setting of intrauterine inflammation.

CCR2 mediates the adverse effects of LPS in the pregnant mouse

In our earlier work, we found that intrauterine (i.u.) and intraperitoneal (i.p.) injection of LPS (10-μg serotype 0111:B4) induced preterm labor (PTL) with high pup mortality, marked systemic inflammatory response and hypotension. Here, we used both i.u. and i.p. LPS models in pregnant wild-type (wt) and CCR2 knockout (CCR2-/-) mice on E16 to investigate the role played by the CCL2/CCR2 system in the response to LPS. Basally, lower numbers of monocytes and macrophages and higher numbers of neutrophils were found in the myometrium, placenta, and blood of CCR2-/- vs. wt mice. After i.u. LPS, parturition occurred at 14 h in both groups of mice. At 7 h post-injection, 70% of wt pups were dead vs. 10% of CCR2-/- pups, but at delivery 100% of wt and 90% of CCR2-/- pups were dead. Myometrial and placental monocytes and macrophages were generally lower in CCR2-/- mice, but this was less consistent in the circulation, lung, and liver. At 7 h post-LPS, myometrial ERK activation was greater and JNK and p65 lower and the mRNA levels of chemokines were higher and of inflammatory cytokines lower in CCR2-/- vs. wt mice. Pup brain and placental inflammation were similar. Using the IP LPS model, we found that all measures of arterial pressure increased in CCR2-/- but declined in wt mice. These data suggest that the CCL2/CCR2 system plays a critical role in the cardiovascular response to LPS and contributes to pup death but does not influence the onset of inflammation-induced PTL.

Anti-Inflammatory Therapies for Treatment of Inflammation-Related Preterm Brain Injury

Despite the prevalence of preterm brain injury, there are no established neuroprotective strategies to prevent or alleviate mild-to-moderate inflammation-related brain injury. Perinatal infection and inflammation have been shown to trigger acute neuroinflammation, including proinflammatory cytokine release and gliosis, which are associated with acute and chronic disturbances in brain cell survival and maturation. These findings suggest the hypothesis that the inhibition of peripheral immune responses following infection or nonspecific inflammation may be a therapeutic strategy to reduce the associated brain injury and neurobehavioral deficits. This review provides an overview of the neonatal immunity, neuroinflammation, and mechanisms of inflammation-related brain injury in preterm infants and explores the safety and efficacy of anti-inflammatory agents as potentially neurotherapeutics.

Brain volumetry in fetuses that deliver very preterm: An MRI pilot study

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Fetuses that subsequently deliver very preterm have a reduction in cortical and extra cerebrospinal fluid volumes.

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If such alterations commence antenatally this suggests a role for earlier administration of neuroprotective agents.

Background

Infants born preterm are at increased risk of neurological complications resulting in significant morbidity and mortality. The exact mechanism and the impact of antenatal factors has not been fully elucidated, although antenatal infection/inflammation has been implicated in both the aetiology of preterm birth and subsequent neurological sequelae. It is therefore hypothesized that processes driving preterm birth are affecting brain development in utero. This study aims to compare MRI derived regional brain volumes in fetuses that deliver < 32 weeks with fetuses that subsequently deliver at term.

Methods

Women at high risk of preterm birth, with gestation 19.4–32 weeks were recruited prospectively. A control group was obtained from existing study datasets. Fetal MRI was performed on a 1.5 T or 3 T MRI scanner: T2-weighted images were obtained of the fetal brain. 3D brain volumetric datsets were produced using slice to volume reconstruction and regional segmentations were produced using multi-atlas approaches for supratentorial brain tissue, lateral ventricles, cerebellum cerebral cortex and extra-cerebrospinal fluid (eCSF). Statistical comparison of control and high-risk for preterm delivery fetuses was performed by creating normal ranges for each parameter from the control datasets and then calculating gestation adjusted z scores. Groups were compared using t-tests.

Results

Fetal image datasets from 24 pregnancies with delivery < 32 weeks and 87 control pregnancies that delivered > 37 weeks were included. Median gestation at MRI of the preterm group was 26.8 weeks (range 19.4–31.4) and control group 26.2 weeks (range 21.7–31.9). No difference was found in supra-tentorial brain volume, ventricular volume or cerebellar volume but the eCSF and cerebral cortex volumes were smaller in fetuses that delivered preterm (p < 0.001 in both cases).

Conclusion

Fetuses that deliver preterm have a reduction in cortical and eCSF volumes. This is a novel finding and needs further investigation. If alterations in brain development are commencing antenatally in fetuses that subsequently deliver preterm, this may present a window for in utero therapy in the future.

Polymicrobial stimulation of human fetal membranes induce neutrophil activation and neutrophil extracellular trap release

Preterm birth is a major contributor to neonatal mortality and morbidity. While the causes of preterm birth remain incompletely understood, infection is a major risk factor, and chorioamnionitis is commonly observed. Chorioamnionitis is characterized by inflammation and neutrophil infiltration of the fetal membranes (FM). We recently reported that human FMs which had been exposed to low levels of bacterial lipopolysaccharide (LPS) recruit neutrophils and activate them, increasing their secretion of pro-inflammatory cytokines, degranulation of myeloperoxidase (MPO), and release of neutrophil extracellular traps (NETs). Herein, we demonstrate that conditioned media (CM) from viral dsRNA (Poly(I:C))-stimulated FMs also increased neutrophil migration, and induced the secretion of inflammatory IL-8 and the release of NETs. Furthermore, CM from FMs stimulated by a combination of bacterial LPS and Poly(I:C) augmented neutrophil NET release, compared to CM from FMs stimulated with either Poly(I:C) or LPS alone. NETs induced by FMs exposed to Poly(I:C), with or without LPS, were released and degraded quicker than those induced by resting or LPS-stimulated FM-CM. These findings indicate that FMs exposed to viral dsRNA promote neutrophil recruitment, activation and NET formation, similar to FMs exposed to bacterial LPS alone. However, in response to FM polymicrobial stimulation the levels and kinetics of NET release are augmented. This work builds upon our understanding of how infections at the maternal-fetal interface may affect neutrophil function.

Maternal environmental enrichment modulates the immune response against an inflammatory challenge during gestation and protects the offspring

The production of pro-inflammatory cytokines during inflammatory processes has been associated with preterm birth (PTB) and fetal injury in humans and mice. We previously demonstrated that exposition to an enriched environment (EE), defined as a noninvasive and biological significant stimulus of the sensory pathway combined with voluntary physical activity, prevented PTB and perinatal death induced by the systemic administration of bacterial lipopolysaccharide (LPS) in mice. This work aimed to analyze whether EE modulates the immune response to the inflammatory process induced by LPS in peripheral blood and the amniotic fluid (AF). We observed that EE modulated maternal white blood cell count and its response to LPS. Furthermore, we found higher levels of IL-10 and a higher percentage of B cells in AF from EE exposed mothers compared to controls. Albeit LPS significantly increased IL-6 levels in AF from both groups, it was 3.6 times higher in control environment (CE) exposed group when compared to EE. Similarly, levels of IL-22 were significantly increased by LPS in both groups, but it was 6.7 times higher in EE group. Interestingly, levels of PGE2 in AF were only increased in the EE-LPS treated group, and a positive correlation between IL-22 and PGE2 levels was observed. During lactation, EE prevented LPS-induced delay in physical landmarks analyzed to assess offspring development. Our results suggest that EE modulates the immune response to systemic LPS-administration protecting the offspring. We propose that an EE-like protocol could be designed for pregnant women aiming at preventing the sequelae present in premature children.

Maternal N-acetyl-cysteine prevents neonatal brain injury associated with necrotizing enterocolitis in a rat model

INTRODUCTION

Preterm infants with necrotizing enterocolitis (NEC) are at increased risk of cerebral injury and neurodevelopmental dysfunction. N-acetyl-cysteine (NAC) is a known anti-inflammatory and antioxidant agent. Currently, there is no prophylactic treatment in clinical use to prevent NEC and its neurodevelopmental sequelae. We sought to determine whether brain inflammation/apoptosis accompanies NEC systemic inflammation, and whether it can be attenuated by maternal NAC treatment during pregnancy and/or in the neonatal period in a rat model.

MATERIAL AND METHODS

An established NEC newborn model (hypoxia 5% O₂ for 10 min and formula feeding thrice daily, beginning on day 1 for 4 days) was used in Sprague-Dawley rat pups (n = 32). An additional group of pups (n = 33) received NAC (300 mg/kg intraperitoneal thrice daily) in addition to NEC conditions (NEC-NAC). Control pups (n = 33) were nursed and remained with the dam in room air. Two additional groups included pups of dams treated once daily with NAC (300 mg/kg intravenous) in the last 3 days of pregnancy. After birth, pups were randomized into NAC-NEC (n = 33) with NEC conditions and NAC-NEC-NAC (n = 36) with additional postnatal NAC treatment. Pups were sacrificed on the fifth day of life. Pup serum interleukin (IL)-6 protein levels, and brain nuclear factor kappa B (NF-κB) p65, neuronal nitric oxide synthase (nNOS), Caspase 3, tumor necrosis factor alpha (TNF-α), IL-6 and IL-1β protein levels were determined by ELISA, western blot and TUNEL staining, and the groups were compared using analysis of variance (ANOVA).

RESULTS

NEC pups had significantly increased serum IL-6 levels compared with the control group as well as increased neuronal apoptosis and brain protein levels of NF-κB, nNOS, Caspase 3, TNF-α, IL-6 and IL-1β compared with control. In all NAC treatment groups, levels of serum IL-6, neuronal apoptosis and brain NF-κB, nNOS, Caspase 3, TNF-α, IL-6 and IL-1β protein levels were significantly reduced compared with the NEC group. The most pronounced decrease was demonstrated within the NAC-NEC-NAC group.

CONCLUSIONS

NAC treatment can attenuate newborn inflammatory response syndrome and decrease offspring brain neuroapoptosis and inflammation in a rat model of NEC by inhibition of NF-κB, nNOS and Caspase 3 pathways.

Melatonin for prevention of fetal lung injury associated with intrauterine inflammation and for improvement of lung maturation

Inflammation is associated with injury to immature lungs, and melatonin administration to preterm newborns with acute respiratory distress improves pulmonary outcomes. We hypothesized that maternally administered melatonin may reduce inflammation, oxidative stress, and structural injury in fetal lung and help fetal lung maturation in a mouse model of intrauterine inflammation (IUI). Mice were randomized to the following groups: control (C), melatonin (M), lipopolysaccharide (LPS; a model of IUI) (L), and LPS with melatonin (ML). Pro-inflammatory cytokines, components of the Hippo pathway, and Yap1/Taz were analyzed in the fetal lung at E18 by real-time RT-qPCR. Confirmatory histochemistry and immunohistochemical analyses (surfactant protein B, vimentin, HIF-1β, and CXCR2) were performed. The gene expression of IL1β in the fetal lung was significantly increased in L compared to C, M, and ML. Taz expression was significantly decreased in L compared to C and M. Taz gene expression in L was significantly decreased compared with those in ML. Immunohistochemical analyses showed that the expression of HIF-1β and CXCR2 was significantly increased in L compared to C, M, and ML. The area of surfactant protein B and vimentin were significantly decreased in L than C, M, or ML in the fetal and neonatal lung. Antenatal maternally administered melatonin appears to prevent fetal lung injury induced by IUI and to help lung maturation. The results from this study results suggest that melatonin could serve as a novel safe preventive and/or therapeutic medicine for preventing fetal lung injury from IUI and for improving lung maturation in prematurity.

Preterm birth prediction in asymptomatic women at mid-gestation using a panel of novel protein biomarkers: the Prediction of PreTerm Labor (PPeTaL) study

BACKGROUND

Accurate prediction of spontaneous preterm labor/preterm birth in asymptomatic women remains an elusive clinical challenge because of the multi-etiological nature of preterm birth.

OBJECTIVE

The aim of this study was to develop and validate an immunoassay-based, multi-biomarker test to predict spontaneous preterm birth.

MATERIALS AND METHODS

This was an observational cohort study of women delivering from December 2017 to February 2019 at 2 maternity hospitals in Melbourne, Australia. Cervicovaginal fluid samples were collected from asymptomatic women at gestational week 16⁺⁰-24⁺⁰, and biomarker concentrations were quantified by enzyme-linked immunosorbent assay. Women were assigned to a training cohort (n = 136) and a validation cohort (n = 150) based on chronological delivery dates.

RESULTS

Seven candidate biomarkers representing key pathways in utero-cervical remodeling were discovered by high-throughput bioinformatic search, and their significance in both in vivo and in vitro studies was assessed. Using a combination of the biomarkers for the first 136 women allocated to the training cohort, we developed an algorithm to stratify term birth (n = 124) and spontaneous preterm birth (n = 12) samples with a sensitivity of 100% (95% confidence interval, 76-100%) and a specificity of 74% (95% confidence interval, 66-81%). The algorithm was further validated in a subsequent cohort of 150 women (n = 139 term birth and n = 11 preterm birth), achieving a sensitivity of 91% (95% confidence interval, 62-100%) and a specificity of 78% (95% confidence interval, 70-84%).

CONCLUSION

We have identified a panel of biomarkers that yield clinically useful diagnostic values when combined in a multiplex algorithm. The early identification of asymptomatic women at risk for preterm birth would allow women to be triaged to specialist clinics for further assessment and appropriate preventive treatment.

Melatonin for prevention of placental malperfusion and fetal compromise associated with intrauterine inflammation-induced oxidative stress in a mouse model

Melatonin has been shown to reduce oxidative stress and mitigate hypercoagulability. We hypothesized that maternally administered melatonin may reduce placental oxidative stress and hypercoagulability associated with exposure to intrauterine inflammation (IUI) and consequently improve fetoplacental blood flow and fetal sequelae. Mice were randomized to the following groups: control (C), melatonin (M), lipopolysaccharide (LPS; a model of IUI) (L), and LPS with melatonin (ML). The expression of antioxidant mediators in the placenta was significantly decreased, while that of pro-inflammatory mediators was significantly increased in L compared to C and ML. The systolic/diastolic ratio, resistance index, and pulsatility index in uterine artery (UtA) and umbilical artery (UA) were significantly increased in L compared with other groups when analyzed by Doppler ultrasonography. The expression of antioxidant mediators in the placenta was significantly decreased, while that of pro-inflammatory mediators was significantly increased in L compared to C and ML. Vascular endothelial damage and thrombi formation, as evidenced by fibrin deposits, were similarly increased in L compared to other groups. Maternal pretreatment with melatonin appears to modulate maternal placental malperfusion, fetal cardiovascular compromise, and fetal neuroinflammation induced by IUI through its antioxidant properties.

The tracking of lipopolysaccharide through the feto-maternal compartment and the involvement of maternal TLR4 in inflammation-induced fetal brain injury

Problem

Exposure to intrauterine inflammation (IUI) has been shown to induce fetal brain injury and increase the risk of acquiring a neurobehavioral disorder. The trafficking of the inflammatory mediator, lipopolysaccharide (LPS), in the pregnant female reproductive tract in the setting of IUI and the precise mechanisms by which inflammation induces fetal brain injury are not fully understood.

Method of study

FITC‐labeled LPS was utilized to induce IUI on E15, tissues were collected, and fluorescence was visualized via the Spectrum IVIS. Embryo transfer was utilized to create divergent maternal and fetal genotypes. Wild‐type (WT) embryos were transferred into TLR4−/− pseudopregnant dams (TLR4−/−_mat/WT_fet). On E15, TLR4−/−_mat/WT_fet dams or their WT controls (WT_mat/WT_fet) received an intrauterine injection of LPS or phosphate‐buffered saline (PBS). Endotoxin and IL‐6 levels were assessed in amniotic fluid, and cytokine expression was measured via QPCR.

Results

Lipopolysaccharide trafficked to the uterus, fetal membranes, placenta, and the fetus and was undetectable in other tissues. Endotoxin was present in the amniotic fluid of all animals exposed to LPS. However, the immune response was blunted in TLR4−/−_mat/WT_fet compared with WT controls.

Conclusion

Intrauterine administered LPS is capable of accessing the entire feto‐placental unit with or without a functional maternal TLR4. Thus, bacteria or bacterial byproducts in the uterus may negatively impact fetal development regardless of the maternal genotype or endotoxin response. Despite the blunted immune response in the TLR4‐deficient dams, an inflammatory response is still ignited in the amniotic cavity and may negatively impact the fetus.

IL‐6 protein expression in the amniotic fluid of WTmat/WTfet and TLR4‐/‐mat/WTfet Pregnant females were treated with an intrauterine dose of LPS (250 μg) or PBS on E15. LPS injection resulted in significantly increased IL‐6 protein in WT animals (*, P = 0.0017) compared to controls. LPS did not significantly elevate IL‐6 levels in the TLR4‐/‐mat/WTfet animals. The WTmat/WTfet dams had a significantly higher immune response compared to their TLR4‐/‐mat/WTfet counterparts (#, P = 0.015).

Administration of melatonin for prevention of preterm birth and fetal brain injury associated with premature birth in a mouse model

PROBLEM

Maternal inflammation leads to preterm birth and perinatal brain injury. Melatonin, through its anti-inflammatory effects, has been shown to be protective against inflammation-induced perinatal adverse effects. However, the immunomodulatory effects of melatonin on preterm birth and prematurity-related morbidity remain unknown. We wanted to investigate the effects of maternally administered melatonin on preterm birth and perinatal brain injury in a mouse model of maternal inflammation.

METHOD OF STUDY

A model of maternal inflammation employing lipopolysaccharide (LPS) was used to mimic the most common clinical scenario of preterm birth, that of maternal inflammation. Mice were randomly divided into the following groups: control, LPS, and LPS with melatonin pre-treatment. Doppler ultrasonography was used to obtain fetal and maternal hemodynamic measurements in utero. Placenta and fetal brains were harvested and analyzed for proinflammatory markers and signs of perinatal brain injury, respectively. Surviving offspring were assessed for neuromotor outcomes.

RESULTS

Melatonin pre-treatment lowered the level of proinflammatory cytokines in the uterus and the placenta, significantly improved LPS-induced acute fetal neuroinflammation and perinatal brain injury, as well as significantly upregulated the SIRT1/Nrf2 signaling pathway to reduce LPS-induced inflammation. Melatonin also prevented adverse neuromotor outcomes in offspring exposed to maternal inflammation.

CONCLUSION

Maternally administered melatonin modulated immune responses to maternal inflammation and decreased preterm birth and perinatal brain injury. These results suggest that melatonin, a safe treatment during pregnancy, may be used as an experimental therapeutic in clinical trials.

The Absence of TLR4 Prevents Fetal Brain Injury in the Setting of Intrauterine Inflammation

BACKGROUND

Exposure to intrauterine inflammation during pregnancy is linked to brain injury and neurobehavioral disorders in affected children. Innate immunity, specifically Toll-like receptor (TLR) signaling pathways are present throughout the reproductive tract as well as in the placenta, fetal membranes, and fetus. The TLR pathways are mechanistically involved in host responses to foreign pathogens and may lead to brain injury associated with prenatal inflammation.

OBJECTIVE

We aimed to determine whether the activation of the TLR4 signaling pathway, in the mother and fetus, is critical to fetal brain injury in the setting of intrauterine inflammation.

METHODS

A mini-laparotomy was performed on time pregnant C57B6 mice and 2 knockout mouse strains lacking the function of the Tlr4 and Myd88 genes on embryonic day 15. Intrauterine injections of Escherichia coli lipopolysaccharide or saline were administered as described previously. Dams were killed 6 hours postsurgery, and placental, amniotic fluid, and fetal brain tissue were collected. To assess brain injury, quantitative polymerase chain reaction (qPCR) analysis was performed on multiple components of the NOTCH signaling pathway, including Hes genes. Interleukin (IL) IL6, IL1β, and CCL5 expression was assessed using qPCR and enzyme-linked immunosorbent assay.

RESULTS

Using an established mouse model of intrauterine inflammation, we demonstrate that the abrogation of TLR4 signaling eliminates the cytokine response in mother and fetus and prevents brain injury associated with increased expression of transcriptional effectors of the NOTCH signaling pathway, Hes1 and Hes5.

CONCLUSIONS

These data show that the activation of the TLR4 signaling pathway is necessary for the development of fetal brain injury in response to intrauterine inflammation.

Omega-3 polyunsaturated fatty acids reduce preterm labor by inhibiting trophoblast cathepsin S and inflammasome activation

Preterm labor is associated with inflammation and infection. The mechanisms underlying the role of omega-3 fatty acid in inflammasome activation and prevention of preterm labor remain unknown. We hypothesized that omega-3 fatty acid can reduce the rate of preterm birth induced by infection and trophoblast inflammation. In the present study, we found that inflammasome-related molecules and IL-1β in trophoblasts were activated by TNF-α derived from lipopolysaccharide (LPS)-stimulated THP-1 cell-conditioned medium (CM) and recombinant TNF-α protein. The results demonstrated that stimulation with TNF-α caused lysosomal rupture in trophoblasts, which accelerated cathepsin S (CTSS) diffusion from lysosomes to the cytosol and activated NLRP1 (nacht domain-leucine-rich repeat, and pyd-containing protein 1) and absent in melanoma 2 (AIM2) inflammasomes, thereby increasing IL-1β secretion. Moreover, in response to LPS challenge, TNF-α increased trophoblast cell death and decreased cell viability through inflammasome and CTSS activation. Stearidonic acid (SDA; 18:4n-3) and docosahexaenoic acid (DHA; 22:6n-3) inhibited inflammasome-related molecule synthesis and CTSS and caspase-1 activation, which further reduced the preterm delivery rate of pregnant mice induced by LPS (92.9 compared with 69.7% (DHA); 92.9 compared with 53.5% (SDA)). Higher expression of TNF-α, IL-1β, prostaglandin E2, and CTSS, but lower resolvin D1 expression, was observed in preterm pregnant mice than in controls. Similarly, resolvin D1 was highly expressed in women with term delivery compared with women with preterm delivery. Thus, SDA and DHA may attenuate macrophage-derived TNF-α inducing CTSS and inflammasome activation, IL-1β secretion, and placental trophoblast cell death. These functions are implicated in the preventive effects of SDA and DHA on preterm labor.

[A review on the relationship between mitochondrial dysfunction and white matter injury in preterm infants]

White matter injury in preterm infants has a complex etiology and can lead to long-term neurocognitive and behavioral deficits, but there are still no specific treatment methods for this disease at present. More and more studies have shown that mitochondrial dysfunction plays an important role in the pathogenesis of white matter injury in preterm infants and might be a common subcellular mechanism of white matter developmental disorder, which involves oxidative stress, reduced ATP synthesis, and disequilibrium of calcium homeostasis. This article reviews the role of mitochondria in brain development and the mechanism of mitochondrial dysfunction, with a hope to perform early intervention of white matter injury in preterm infants by protecting mitochondrial function, so as to provide a reference for improving the neurodevelopmental outcome of preterm infants who survive.

Maternal pomegranate juice attenuates maternal inflammation-induced fetal brain injury by inhibition of apoptosis, neuronal nitric oxide synthase, and NF-κB in a rat model

BACKGROUND

Maternal inflammation is a risk factor for neonatal brain injury and future neurological deficits. Pomegranates have been shown to exhibit anti-inflammatory, anti-apoptotic and anti-oxidant activities.

OBJECTIVE

We hypothesized that pomegranate juice (POM) may attenuate fetal brain injury in a rat model of maternal inflammation.

STUDY DESIGN

Pregnant rats (24 total) were randomized for intraperitoneal lipopolysaccharide (100 μg/kg) or saline at time 0 at 18 days of gestation. From day 11 of gestation, 12 dams were provided ad libitum access to drinking water, and 12 dams were provided ad libitum access to drinking water with pomegranate juice (5 mL per day), resulting in 4 groups of 6 dams (saline/saline, pomegranate juice/saline, saline/lipopolysaccharide, pomegranate juice/lipopolysaccharide). All dams were sacrificed 4 hours following the injection and maternal blood and fetal brains were collected from the 4 treatment groups. Maternal interleukin-6 serum levels and fetal brain caspase 3 active form, nuclear factor-κB p65, neuronal nitric oxide synthase (phosphoneuronal nitric oxide synthase), and proinflammatory cytokine levels were determined by enzyme-linked immunosorbent assay and Western blot.

RESULTS

Maternal lipopolysaccharide significantly increased maternal serum interleukin-6 levels (6039 ± 1039 vs 66 ± 46 pg/mL; P < .05) and fetal brain caspase 3 active form, nuclear factor-κB p65, phosphoneuronal nitric oxide synthase, and the proinflammatory cytokines compared to the control group (caspase 3 active form 0.26 ± 0.01 vs 0.20 ± 0.01 U; nuclear factor-κB p65 0.24 ± 0.01 vs 0.1 ± 0.01 U; phosphoneuronal nitric oxide synthase 0.23 ± 0.01 vs 0.11 ± 0.01 U; interleukin-6 0.25 ± 0.01 vs 0.09 ± 0.01 U; tumor necrosis factor-α 0.26 ± 0.01 vs 0.12 ± 0.01 U; chemokine (C-C motif) ligand 2 0.23 ± 0.01 vs 0.1 ± 0.01 U). Maternal supplementation of pomegranate juice to lipopolysaccharide-exposed dams (pomegranate juice/lipopolysaccharide) significantly reduced maternal serum interleukin-6 levels (3059 ± 1121 pg/mL, fetal brain: caspase 3 active form (0.2 ± 0.01 U), nuclear factor-κB p65 (0.22 ± 0.01 U), phosphoneuronal nitric oxide synthase (0.19 ± 0.01 U) as well as the brain proinflammatory cytokines (interleukin-6, tumor necrosis factor-α and chemokine [C-C motif] ligand 2) compared to lipopolysaccharide group.

CONCLUSION

Maternal pomegranate juice supplementation may attenuate maternal inflammation-induced fetal brain injury. Pomegranate juice neuroprotective effects might be secondary to the suppression of both the maternal inflammatory response and inhibition of fetal brain apoptosis, neuronal nitric oxide synthase, and nuclear factor-κB activation.

Impact of gestational nicotine exposure on intrauterine and fetal infection in a rodent model

We investigated the interaction between prenatal nicotine exposure and intrauterine infection using established rat models. Beginning at gestation day (GD) 6, dams were continuously infused with either saline or 6 mg/kg/day nicotine (Nic). At GD 14, dams received either sterile broth or 10⁵ colony-forming units Mycoplasma pulmonis (MP), resulting in four treatment groups: control (4 dams, 33 fetal units); MP only (5 dams, 55 fetal units); Nic only (5 dams, 61 fetal units), and Nic + MP (7 dams, 82 fetal units). At GD 18, nicotine exposure significantly increased (P ≤ 0.02) the percentage of amniotic fluids and fetuses infected by MP but did not impact colonization rates of maternal sites. Nicotine exposure significantly reduced the numbers of MP in the placenta required for high microbial loads (≥10⁴ color-changing units) in the amniotic fluid (P < 0.01). Fetal inflammatory response lesions were most extensive in the Nic only and Nic + MP groups (P < 0.0001). Control and MP only placentas were interleukin (IL)10-dominant, consistent with an M2/Th2 environment. Placentas exposed to nicotine shifted to a neutral environment, with equivalent levels of interferon gamma (IFNG) and IL10. Both IL6 and tumor necrosis factor (TNF) levels in amniotic fluid were highly elevated when both nicotine and infection were present. Our study suggests that prenatal exposure to nicotine increases the risk for intrauterine infection, lowers the infectious dose required to breach the placental barrier and infect the amniotic fluid and fetus, and alters the pathology and inflammatory profile associated with maternal and fetal sites.

Zika-virus-infected human full-term placental explants display pro-inflammatory responses and undergo apoptosis

Zika virus (ZIKV) is a flavivirus that has been highly correlated with the development of neurological disorders and other malformations in newborns and stillborn fetuses after congenital infection. This association is supported by the presence of ZIKV in the fetal brain and amniotic fluid, and findings suggest that infection of the placental barrier is a critical step for fetal ZIKV infection in utero. Therefore, relevant models to investigate the interaction between ZIKV and placental tissues are essential for understanding the pathogenesis of Zika syndrome. In this report, we demonstrate that explant tissue from full-term human placentas sustains a productive ZIKV infection, though the results depend on the strain. Viral infection was found to be associated with pro-inflammatory cytokine expression and apoptosis of the infected tissue, and these findings confirm that placental explants are targets of ZIKV replication. We propose that human placental explants are useful as a model for studying ZIKV infection ex vivo.

Intrauterine inflammation reduces postnatal neurogenesis in the hippocampal subgranular zone and leads to accumulation of hilar ectopic granule cells

Prenatal inflammation is associated with poor neurobehavioral outcomes in exposed offspring. A common route of exposure for the fetus is intrauterine infection, which is often associated with preterm birth. Hippocampal development may be particularly vulnerable to an inflammatory insult during pregnancy as this region remains highly neurogenic both prenatally and postnatally. These studies sought to determine if intrauterine inflammation specifically altered hippocampal neurogenesis and migration of newly produced granule neurons during the early postnatal period. Microglial and astroglial cell populations known to play a role in the regulation of postnatal neurogenesis were also examined. We show that intrauterine inflammation significantly reduced hippocampal neurogenesis between postnatal days 7 (P7) and P14 as well as decreased granule cell density at P28. Ectopic migration of granule cells was observed in LPS-exposed mice at P14, but not at P28. Intrauterine inflammation had no effect on hippocampal astrocyte or microglia density or on apoptosis rate at the postnatal time points examined. Thus, exposure to intrauterine inflammation disrupts early postnatal neurogenesis and leads to aberrant migration of newly born granule cells.

Exposure to intrauterine inflammation alters metabolomic profiles in the amniotic fluid, fetal and neonatal brain in the mouse

INTRODUCTION

Exposure to prenatal inflammation is associated with diverse adverse neurobehavioral outcomes in exposed offspring. The mechanism by which inflammation negatively impacts the developing brain is poorly understood. Metabolomic profiling provides an opportunity to identify specific metabolites, and novel pathways, which may reveal mechanisms by which exposure to intrauterine inflammation promotes fetal and neonatal brain injury. Therefore, we investigated whether exposure to intrauterine inflammation altered the metabolome of the amniotic fluid, fetal and neonatal brain. Additionally, we explored whether changes in the metabolomic profile from exposure to prenatal inflammation occurs in a sex-specific manner in the neonatal brain.

METHODS

CD-1, timed pregnant mice received an intrauterine injection of lipopolysaccharide (50 μg/dam) or saline on embryonic day 15. Six and 48 hours later mice were sacrificed and amniotic fluid, and fetal brains were collected (n = 8/group). Postnatal brains were collected on day of life 1 (n = 6/group/sex). Global biochemical profiles were determined using ultra performance liquid chromatography/tandem mass spectrometry (Metabolon Inc.). Statistical analyses were performed by comparing samples from lipopolysaccharide and saline treated animals at each time point. For the P1 brains, analyses were stratified by sex.

RESULTS/CONCLUSIONS

Exposure to intrauterine inflammation induced unique, temporally regulated changes in the metabolic profiles of amniotic fluid, fetal brain and postnatal brain. Six hours after exposure to intrauterine inflammation, the amniotic fluid and the fetal brain metabolomes were dramatically altered with significant enhancements of amino acid and purine metabolites. The amniotic fluid had enhanced levels of several members of the (hypo) xanthine pathway and this compound was validated as a potential biomarker. By 48 hours, the number of altered biochemicals in both the fetal brain and the amniotic fluid had declined, yet unique profiles existed. Neonatal pups exposed to intrauterine inflammation have significant alterations in their lipid metabolites, in particular, fatty acids. These sex-specific metabolic changes within the newborn brain offer an explanation regarding the sexual dimorphism of certain psychiatric and neurobehavioral disorders associated with exposure to prenatal inflammation.

Viral Infection Sensitizes Human Fetal Membranes to Bacterial Lipopolysaccharide by MERTK Inhibition and Inflammasome Activation

Chorioamnionitis, premature rupture of fetal membranes (FMs), and subsequent preterm birth are associated with local infection and inflammation, particularly IL-1β production. Although bacterial infections are commonly identified, other microorganisms may play a role in the pathogenesis. Because viral pandemics, such as influenza, Ebola, and Zika, are becoming more common, and pregnant women are at increased risk for associated complications, this study evaluated the impact that viral infection had on human FM innate immune responses. This study shows that a herpes viral infection of FMs sensitizes the tissue to low levels of bacterial LPS, giving rise to an exaggerated IL-1β response. Using an ex vivo human FM explant system and an in vivo mouse model of pregnancy, we report that the mechanism by which this aggravated inflammation arises is through the inhibition of the TAM receptor, MERTK, and activation of the inflammasome. The TAM receptor ligand, growth arrest specific 6, re-establishes the normal FM response to LPS by restoring and augmenting TAM receptor and ligand expression, as well as by preventing the exacerbated IL-1β processing and secretion. These findings indicate a novel mechanism by which viruses alter normal FM immune responses to bacteria, potentially giving rise to adverse pregnancy outcomes.

The unique immunological and microbial aspects of pregnancy

The comparison of the immunological state of pregnancy to an immunosuppressed host-graft model continues to lead research and clinical practice to ill-defined approaches. This Review discusses recent evidence that supports the idea that immunological responses at the receptive maternal-fetal interface are not simply suppressed but are instead highly dynamic. We discuss the crucial role of trophoblast cells in shaping not only the way in which immune cells respond to the invading blastocyst but also how they collectively react to external stimuli. We also discuss the role of the microbiota in promoting a tolerogenic maternal immune system and highlight how subclinical viral infections can disrupt this status quo, leading to pregnancy complications.

Maternal Inflammation, Fetal Brain Implications and Suggested Neuroprotection: A Summary of 10 Years of Research in Animal Models

A growing body of evidence implies that maternal inflammation during pregnancy is associated with increased risk of neurodevelopmental disorders in the offspring. The pathophysiological mechanisms by which maternal inflammation evokes fetal brain injury and contributes to long-term adverse neurological outcomes are not completely understood. In this review, we summarize 10 years of our research experience on maternal inflammation and the implications upon the fetal/offspring brain. We review our findings regarding the underlying mechanisms that connects maternal inflammation and fetal brain injuries (e.g. cytokines, oxidative stress); we discuss our imaging, pathological and behavioral test results which support brain damage following maternal inflammation; and finally we describe some of the therapeutic strategies which might prevent the damage.

The Local and Systemic Immune Response to Intrauterine LPS in the Prepartum Mouse

Inflammation plays a key role in human term and preterm labor (PTL). Intrauterine LPS has been widely used to model inflammation-induced complications of pregnancy, including PTL. It has been shown to induce an intense myometrial inflammatory cell infiltration, but the role of LPS-induced inflammatory cell activation in labor onset and fetal demise is unclear. We investigated this using a mouse model of PTL, where an intrauterine injection of 10 μg of LPS (serotype 0111:B4) was given at E16 of CD1 mouse pregnancy. This dose induced PTL at an average of 12.7 h postinjection in association with 85% fetal demise. Flow cytometry showed that LPS induced a dramatic systemic inflammatory response provoking a rapid and marked leucocyte infiltration into the maternal lung and liver in association with increased cytokine levels. Although there was acute placental inflammatory gene expression, there was no corresponding increase in fetal brain inflammatory gene expression until after fetal demise. There was marked myometrial activation of NFκB and MAPK/AP-1 systems in association with increased chemokine and cytokine levels, both of which peaked with the onset of parturition. Myometrial macrophage and neutrophil numbers were greater in the LPS-injected mice with labor onset only; prior to labor, myometrial neutrophils and monocytes numbers were greater in PBS-injected mice, but this was not associated with an earlier onset of labor. These data suggest that intrauterine LPS induces parturition directly, independent of myometrial inflammatory cell infiltration, and that fetal demise occurs without fetal inflammation. Intrauterine LPS provokes a marked local and systemic inflammatory response but with limited inflammatory cell infiltration into the myometrium or placenta.

Neuroprotective effects of antenatal magnesium sulfate under inflammatory conditions in a Sprague-Dawley pregnant rat model

OBJECTIVE

Antenatal magnesium sulfate (MgSO₄) is recommended for fetal neuroprotection. The aim of this animal study was to assess the neuroprotective effect of in utero exposure to MgSO₄, under inflammatory conditions.

METHODS

Timed pregnant Sprague-Dawley (SD) rats (n = 29) received four intra-peritoneal (IP) injections of lipopolysaccharides (LPS; 200 μg/kg), combined with increasing concentrations of MgSO₄ (25, 50 or 100 mg/kg, n = 19) or saline solution (SS; n = 10). In the second set of experiments, animals (n = 8) received a single IP injection of i) LPS (500 μg/kg), MgSO₄ (50 mg/kg) and SS (n = 4) or ii) LPS (500 μg/kg), MgSO₄ (50 mg/kg) and IL-6 (12 μg/kg) (n = 4). Neurodevelopmental outcomes of surviving pups (n = 212) were assessed by the open field and the rotarod tests.

RESULTS

Pups' average weight at postnatal day (P) 25 was 75.77 g and 89.08 g in MgSO₄ and control groups, respectively (p = 0.02). Pups in MgSO₄ group have traveled a shorter distance and have shown reduced motor balance and coordination (p < 0.01). Average weight of pups receiving (LPS + MgSO₄+ IL-6) was 92.26 g at P25, compared to 75.86 g in (LPS + MgSO₄+SS) group (p < 0.05).

CONCLUSIONS

In our model, MgSO₄ induces pup's growth retardation and motor deficits, which may partly be related to a lower IL-6 circulating concentration.

Assessing the fetal effects of maternal obesity via transcriptomic analysis of cord blood: a prospective case-control study

OBJECTIVE

To analyse fetal gene expression at term using umbilical cord blood, in order to provide insights into the effects of maternal obesity on human development.

DESIGN

Prospective case-control study.

SETTING

Academic tertiary care centre.

POPULATION

Eight obese (body mass index ≥30 kg/m(2)) and eight lean (body mass index <25 kg/m(2)) pregnant women undergoing prelabour caesarean delivery at term.

METHODS

Women were matched for gestational age and fetal sex. Cord blood RNA was extracted and hybridised to gene expression arrays. Differentially regulated genes were identified using paired t-tests and the Benjamini-Hochberg correction. Functional analyses were performed using Ingenuity Pathway Analysis, BioGPS and Gene Set Enrichment Analysis with a fetal-specific annotation. Z-scores ≥2.0 or P-values <0.01 were considered significant.

MAIN OUTCOME MEASURE

Functions of differentially regulated genes in fetuses of obese women.

RESULTS

A total of 701 differentially regulated genes were identified, producing an expression profile implicating neurodegeneration, decreased survival of sensory neurons, and decreased neurogenesis in the fetuses of obese women. Upstream regulators related to inflammatory signalling were significantly activated; those related to insulin receptor signalling, lipid homeostasis, regulation of axonal guidance, and cellular response to oxidative stress were significantly inhibited. Of 26 tissue-specific genes that were differentially regulated in fetuses of obese women, six mapped to the fetal brain.

CONCLUSION

Maternal obesity affects fetal gene expression at term, implicating dysregulated brain development, inflammatory and immune signalling, glucose and lipid homeostasis, and oxidative stress. This may have implications for postnatal neurodevelopment and metabolism.

Neonatal Infection and Later Neurodevelopmental Risk in the Very Preterm Infant

OBJECTIVES

To document associations between confirmed and suspected neonatal infection and motor, cognitive, educational, and mental health outcomes of very preterm (VPT)-born children at 9 years of age; to examine the potential intervening role of cerebral white matter abnormalities (WMAs) and structural development on term magnetic resonance imaging.

STUDY DESIGN

A regional cohort of 110 infants born VPT in Christchurch, New Zealand were studied from birth to age of 9 years. Confirmed infection was defined as positive blood, cerebrospinal fluid or urine culture, and/or necrotizing enterocolitis ≥ stage 2. Suspected infection was defined as ≥ 5 days of antibiotics with evidence of clinical correlates. At term gestational equivalence, infants underwent structural magnetic resonance imaging. At age 9 years, neuromotor function, IQ, educational achievement, and mental health were assessed.

RESULTS

During hospitalization, 25% of VPT infants had confirmed and 23% had suspected infection. Longer-term neurodevelopmental impairments were largely confined to infants with confirmed infection (relative risk 1.4-3.1, vs uninfected). After accounting for other neonatal factors, these infants were at increased risk of severe motor impairment (OR 3.3, 95% CI 1.3-8), attention deficit hyperactivity disorder (ADHD) (OR 3.6, 95% CI 1.6-8), and IQ delay (OR 2.0, 95% CI 1-3.9). Cerebral WMAs contributed to associations between confirmed infection and motor and IQ impairments but not to ADHD (P = .005).

CONCLUSIONS

Confirmed neonatal infection heightens VPT infants' risk for neurodevelopmental impairment. WMA appears to be an important intervening factor linking infection and severe motor and IQ impairments. Further analysis of the neurologic mechanism accounting for ADHD in infants with infection is needed.

In vitro progesterone modulation on bacterial endotoxin-induced production of IL-1β, TNFα, IL-6, IL-8, IL-10, MIP-1α, and MMP-9 in pre-labor human term placenta

BACKGROUND

During human pregnancy, infection/inflammation represents an important factor that increases the risk of developing preterm labor. The purpose of this study was to determine if pre-treatment with progesterone has an immunomodulatory effect on human placenta production of endotoxin-induced inflammation and degradation of extracellular matrix markers.

METHODS

Placentas were obtained under sterile conditions from pregnancies delivered at term before the onset of labor by cesarean section. Explants from central cotyledons of 10 human placentas were pre-treated with different concentrations of progesterone (0.01, 01, 1.0 μM) and then stimulated with 1000 ng/mL of LPS of Escherichia coli. Cytokines TNFα, IL-1β, IL-6, IL-8, MIP-1α, IL-10 concentrations in the culture medium were then measured by specific ELISA. Secretion profile of MMP-9 was evaluated by ELISA and zymogram. Statistical differences were determined by one-way ANOVA followed by the appropriate ad hoc test; P < 0.05 was considered statistically significant.

RESULTS

In comparison to the explants incubated with vehicle, the LPS treatment led to a significant increase in the level of all cytokines. In comparison to the explants treated only with LPS, pre-treatment with 0.01-1.0 μM progesterone significantly blunted (73, 56, 56, 75, 25, 48 %) the secretion of TNF-α, IL-1β, IL-6, IL-8, MIP-1α, IL-10, respectively. The MMP-9 induced by LPS treatment was inhibited only with the highest concentration of progesterone. Mifepristone (RU486) blocked the immunosuppressive effect of progesterone.

CONCLUSIONS

The present results support the concept that progesterone could be part of the compensatory mechanism that limits the inflammation-induced cytotoxic effects associated with an infection process during gestation.

Specific Lipopolysaccharide Serotypes Induce Differential Maternal and Neonatal Inflammatory Responses in a Murine Model of Preterm Labor

Intrauterine inflammation is recognized as a key mediator of both normal and preterm birth but is also associated with neonatal neurological injury. Lipopolysaccharide (LPS) is often used to stimulate inflammatory pathways in animal models of infection/inflammation-induced preterm labor; however, inconsistencies in maternal and neonatal responses to LPS are frequently reported. We hypothesized that LPS serotype-specific responses may account for a portion of these inconsistencies. Four different Escherichia coli LPS serotypes (O111:B4, O55:B5, O127:B8, and O128:B12) were administered to CD1 mice via intrauterine injection at gestational day 16. Although control animals delivered at term 60 ± 15 hours postinjection (p.i.), those administered with O111:B4 delivered 7 ± 2 hours p.i., O55:B5 delivered 10 ± 3 hours p.i., O127:B8 delivered 16 ± 10 hours p.i., and O128:B12 delivered 17 ± 2 hours p.i. (means ± SD). A correlation between the onset of preterm labor and myometrial activation of the inflammatory transcription factor, activator protein 1, but not NF-κB was observed. Specific LPS serotypes induced differential activation of downstream contractile and inflammatory pathways in myometrium and neonatal pup brain. Our findings demonstrate functional disparity in inflammatory pathway activation in response to differing LPS serotypes. Selective use of LPS serotypes may represent a useful tool for targeting specific inflammatory response mechanisms in these models.

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

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

White matter injury and the inflammatory response following neonatal cardiac surgery

White matter injury (WMI) is a known complication following neonatal heart surgery in term infants. In preterm infants, WMI has been associated with the degree of systemic inflammation. It is not known whether inflammation is an important mechanism of WMI as documented by magnetic resonance imaging (MRI) following neonatal heart surgery with cardiopulmonary bypass. Term neonates with congenital heart disease were enrolled in a prospective study with postoperative MRI. White matter injury was recorded by the number of T1 hyperintense foci with >5 foci consistent with significant WMI. Eleven candidate cytokine markers (INF-gamma, TNF-alpha, IL-1 beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, and IL-13) were assayed preoperatively and daily for 5 days following surgery. Multiple clinical factors were recorded and correlated with WMI. Ninety-two subjects were enrolled in the study. The median age at surgery was 5 days (interquartile range 4-7 days). Compared with the presurgery level, there were statistically significant increases (p < 0.005) for 8 out of 11 inflammatory markers. In all, 64 postoperative MRIs were performed. No significant correlation was detected between WMI and clinical variables or inflammatory markers assessed immediately postoperative and on postoperative days 1 and 3, with exception of IL-1 beta on postoperative day 1. WMI correlates poorly with the systemic inflammatory response after congenital heart surgery and a number of herein measured clinical factors. WMI following neonatal heart surgery is a complex, still incompletely understood phenomenon that warrants continued investigation.

Murine model: maternal administration of stem cells for prevention of prematurity

OBJECTIVE

Using a mouse model of intrauterine inflammation, we have demonstrated that exposure to inflammation induces preterm birth and perinatal brain injury. Mesenchymal stem cells (MSCs) have been shown to exhibit immunomodulatory effects in many inflammatory conditions. We hypothesized that treatment with human adipose tissue-derived MSCs may decrease the rate of preterm birth and perinatal brain injury through changes in antiinflammatory and regulatory milieu.

STUDY DESIGN

A mouse model of intrauterine inflammation was used with the following groups: (1) control; (2) intrauterine inflammation (lipopolysaccharide); and (3) intrauterine lipopolysaccharide+intraperitoneal (MSCs). Preterm birth was investigated. Luminex multiplex enzyme-linked immunosorbent assays were performed for protein levels of cytokines in maternal and fetal compartments. Immunofluorescent staining was used to identify and localize MSCs and to examine microglial morphologic condition and neurotoxicity in perinatal brain. Behavioral testing was performed at postnatal day 5.

RESULTS

Pretreatment with MSCs significantly decreased the rate of preterm birth by 21% compared with the lipopolysaccharide group (P<.01). Pretreatment was associated with increased interleukin-10 in maternal serum, increased interleukin-4 in placenta, decreased interleukin-6 in fetal brain (P<.05), decreased microglial activation (P<.05), and decreased fetal neurotoxicity (P<.05). These findings were associated with improved neurobehavioral testing at postnatal day 5 (P<.05). Injected MSCs were localized to placenta.

CONCLUSION

Maternally administered MSCs appear to modulate maternal and fetal immune response to intrauterine inflammation in the model and decrease preterm birth, perinatal brain injury, and motor deficits in offspring mice.

Anti-inflammatory prostaglandins for the prevention of preterm labour

Preterm birth occurs in 10-12% of pregnancies and is the primary cause of neonatal mortality and morbidity. Tocolytic therapies have long been the focus for the prevention of preterm labour, yet they do not significantly improve neonatal outcome. A direct causal link exists between infection-induced inflammation and preterm labour. As inflammation and infection are independent risk factors for poor neonatal outcome, recent research focus has been shifted towards exploring the potential for anti-inflammatory strategies. Nuclear factor kappa B (NFκB) is a transcription factor that controls the expression of many labour-associated genes including PTGS2 (COX2), prostaglandins (PGs) and the oxytocin receptor (OXTR) as well as key inflammatory genes. Targeting the inhibition of NFκB is therefore an attractive therapeutic approach for both the prevention of preterm labour and for reducing neonatal exposure to inflammation. While PGs are considered to be pro-labour and pro-inflammatory, the cyclopentenone PG 15-deoxy-Δ(12,14)PGJ2 (15d-PGJ2) exhibits anti-inflammatory properties via the inhibition of NFκB in human amniocytes, myocytes and peripheral blood mononuclear cells in vitro. 15d-PGJ2 also delays inflammation-induced preterm labour in the mouse and significantly increases pup survival. This review examines the current understanding of inflammation in the context of labour and discusses how anti-inflammatory PGs may hold promise for the prevention of preterm labour and improved neonatal outcome.

The diagnostic performance of the Mass Restricted (MR) score in the identification of microbial invasion of the amniotic cavity or intra-amniotic inflammation is not superior to amniotic fluid interleukin-6

OBJECTIVE

Intra-amniotic infection/inflammation are major causes of spontaneous preterm labor and delivery. However, diagnosis of intra-amniotic infection is challenging because most are subclinical and amniotic fluid (AF) cultures take several days before results are available. Several tests have been proposed for the rapid diagnosis of microbial invasion of the amniotic cavity (MIAC) or intra-amniotic inflammation. The aim of this study was to examine the diagnostic performance of the AF Mass Restricted (MR) score in comparison with interleukin-6 (IL-6) and matrix metalloproteinase-8 (MMP-8) for the identification of MIAC or inflammation.

METHODS

AF samples were collected from patients with singleton gestations and symptoms of preterm labor (n = 100). Intra-amniotic inflammation was defined as >100 white blood cells/mm(3) (WBCs) in AF; MIAC was defined as a positive AF culture. AF IL-6 and MMP-8 were determined using ELISA. The MR score was obtained using the Surface-Enhanced Laser Desorption Ionization Time of Flight (SELDI-TOF) mass spectrometry. Sensitivity and specificity were calculated and logistic regression models were fit to construct receiver-operating characteristic (ROC) curves for the identification of each outcome. The McNemar's test and paired sample non-parametric statistical techniques were used to test for differences in diagnostic performance metrics.

RESULTS

(1) The prevalence of MIAC and intra-amniotic inflammation was 34% (34/100) and 40% (40/100), respectively; (2) there were no significant differences in sensitivity of the three tests under study (MR score, IL-6 or MMP-8) in the identification of either MIAC or intra-amniotic inflammation (using the following cutoffs: MR score >2, IL-6 >11.4 ng/mL, and MMP-8 >23 ng/mL); (3) there was no significant difference in the sensitivity among the three tests for the same outcomes when the false positive rate was fixed at 15%; (4) the specificity for IL-6 was not significantly different from that of the MR score in identifying either MIAC or intra-amniotic inflammation when using previously reported thresholds; and (5) there were no significant differences in the area under the ROC curve when comparing the MR score, IL-6 or MMP-8 in the identification of these outcomes.

CONCLUSIONS

IL-6 and the MR score have equivalent diagnostic performance in the identification of MIAC or intra-amniotic inflammation. Selection from among these three tests (MR score, IL-6 and MMP-8) for diagnostic purposes should be based on factors such as availability, reproducibility, and cost. The MR score requires a protein chip and a SELDI-TOF instrument which are not widely available or considered "state of the art". In contrast, immunoassays for IL-6 can be performed in the majority of clinical laboratories.

Single- and double-stranded viral RNA generate distinct cytokine and antiviral responses in human fetal membranes

There has been growing interest in the role of viral infections and their association with adverse pregnancy outcomes. However, little is known about the impact viral infections have on the fetal membranes (FM). Toll-like receptors (TLR) are thought to play a role in infection-associated inflammation at the maternal-fetal interface. Therefore, the objective of this study was to characterize the cytokine profile and antiviral response in human FMs exposed to viral dsRNA, which activates TLR3, and viral ssRNA, which activates TLR8; and to determine the mechanisms involved. The viral dsRNA analog, Poly(I:C), induced up-regulated secretion of MIP-1α, MIP-1β, RANTES and TNF-α, and down-regulated interleukin (IL)-2 and VEGF secretion. In contrast, viral ssRNA induced a broader panel of cytokines in the FMs by up-regulating the secretion of IL-1β, IL-2, IL-6, G-CSF, MCP-1, MIP-1α, MIP-1β, RANTES, TNF-α and GRO-α. Using inhibitory peptides against TLR adapter proteins, FM secretion of MIP-1β and RANTES in response to Poly(I:C) was MyD88 dependent; MIP-1α secretion was dependent on MyD88 and TRIF; and TNF-α production was independent of MyD88 and TRIF. Viral ssRNA-induced FM secretion of IL-1β, IL-2, IL-6, G-CSF, MIP-1α, RANTES and GRO-α was dependent on MyD88 and TRIF; MIP-1β was dependent upon TRIF, but not MyD88; and TNF-α and MCP-1 secretion was dependent on neither. Poly(I:C), but not ssRNA, induced an FM antiviral response by up-regulating the expression of IFNβ, myxovirus-resistance A, 2',5'-oligoadenylate synthetase and apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G. These findings demonstrate that human FMs respond to two viral signatures by generating distinct inflammatory cytokine/chemokine profiles and antiviral responses through different mechanisms.

Unmyelinated white matter loss in the preterm brain is associated with early increased levels of end-tidal carbon monoxide

Objective

Increased levels of end-tidal carbon monoxide (ETCOc) in preterm infants during the first day of life are associated with oxidative stress, inflammatory processes and adverse neurodevelopmental outcome at 2 years of age. Therefore, we hypothesized that early ETCOc levels may also be associated with impaired growth of unmyelinated cerebral white matter.

Methods

From a cohort of 156 extremely and very preterm infants in which ETCOc was determined within 24 h after birth, in 36 infants 3D-MRI was performed at term-equivalent age to assess cerebral tissue volumes of important brain regions.

Results

Linear regression analysis between cerebral ventricular volume, unmyelinated white matter/total brain volume-, and cortical grey matter/total brain volume-ratio and ETCOc showed a positive, negative and positive correlation, respectively. Multivariable analyses showed that solely ETCOc was positively related to cerebral ventricular volume and cortical grey matter/total brain volume ratio, and that solely ETCOc was inversely related to the unmyelinated white matter/total brain volume ratio, suggesting that increased levels of ETCOc, associated with oxidative stress and inflammation, were related with impaired growth of unmyelinated white matter.

Conclusion

Increased values of ETCOc, measured within the first 24 hours of life may be indicative of oxidative stress and inflammation in the immediate perinatal period, resulting in impaired growth of the vulnerable unmyelinated white matter of the preterm brain.

IL-1 receptor blockade prevents fetal cortical brain injury but not preterm birth in a mouse model of inflammation-induced preterm birth and perinatal brain injury

PROBLEM

Exposure to intrauterine inflammation, associated with preterm birth, has been linked to a devastating spectrum of neurobehavioral disorders. Mechanisms of this injury are unknown. Using a mouse model of intrauterine inflammation, we have observed a disruption of fetal neuronal morphology along with a marked elevation of interleukin (IL)-1β in the fetal brain and placenta. In this study, we hypothesized that IL-1 plays a key role in perinatal brain injury.

METHOD OF STUDY

Utilizing a mouse model of inflammation-induced preterm birth, we investigated the role of IL-1 in fetal cortical injury as well as preterm birth. In these studies, dams received systemic treatment with IL-1 receptor antagonist prior to administration of intrauterine inflammation.

RESULTS

Systemic maternal antagonism of IL-1 improved fetal cortical neuronal injury associated with the exposure to intrauterine inflammation, without affecting the phenotype of preterm birth. IL-1 receptor antagonist blocked activation of neuronal nitric oxide synthase in perinatal cortex, a key enzyme implicated in neurotoxicity.

CONCLUSION

Our data suggest that fetal cortical brain injury and preterm birth may occur by divergent mechanisms. Furthermore, our studies indicate maternal administration of IL-1 receptor antagonist (IL-1RA) blocked neuronal nitric oxide synthase activation observed in the brain cortex and, we speculate, that this alteration in activation leads to demonstrated decreased neurotoxicity.

A novel molecular microbiologic technique for the rapid diagnosis of microbial invasion of the amniotic cavity and intra-amniotic infection in preterm labor with intact membranes

PROBLEM

The diagnosis of microbial invasion of the amniotic cavity (MIAC) has been traditionally performed using traditional cultivation techniques, which require growth of microorganisms in the laboratory. Shortcomings of culture methods include the time required (days) for identification of microorganisms, and that many microbes involved in the genesis of human diseases are difficult to culture. A novel technique combines broad-range real-time polymerase chain reaction with electrospray ionization time-of-flight mass spectrometry (PCR/ESI-MS) to identify and quantify genomic material from bacteria and viruses.

METHOD OF STUDY

AF samples obtained by transabdominal amniocentesis from 142 women with preterm labor and intact membranes (PTL) were analyzed using cultivation techniques (aerobic, anaerobic, and genital mycoplasmas) as well as PCR/ESI-MS. The prevalence and relative magnitude of intra-amniotic inflammation [AF interleukin 6 (IL-6) concentration ≥ 2.6 ng/mL], acute histologic chorioamnionitis, spontaneous preterm delivery, and perinatal mortality were examined.

RESULTS

(i) The prevalence of MIAC in patients with PTL was 7% using standard cultivation techniques and 12% using PCR/ESI-MS; (ii) seven of ten patients with positive AF culture also had positive PCR/ESI-MS [≥17 genome equivalents per PCR reaction well (GE/well)]; (iii) patients with positive PCR/ESI-MS (≥17 GE/well) and negative AF cultures had significantly higher rates of intra-amniotic inflammation and acute histologic chorioamnionitis, a shorter interval to delivery [median (interquartile range-IQR)], and offspring at higher risk of perinatal mortality, than women with both tests negative [90% (9/10) versus 32% (39/122) OR: 5.6; 95% CI: 1.4-22; (P < 0.001); 70% (7/10) versus 35% (39/112); (P = 0.04); 1 (IQR: <1-2) days versus 25 (IQR: 5-51) days; (P = 0.002), respectively]; (iv) there were no significant differences in these outcomes between patients with positive PCR/ESI-MS (≥17 GE/well) who had negative AF cultures and those with positive AF cultures; and (v) PCR/ESI-MS detected genomic material from viruses in two patients (1.4%).

CONCLUSION

(i) Rapid diagnosis of intra-amniotic infection is possible using PCR/ESI-MS; (ii) the combined use of biomarkers of inflammation and PCR/ESI-MS allows for the identification of specific bacteria and viruses in women with preterm labor and intra-amniotic infection; and (iii) this approach may allow for administration of timely and specific interventions to reduce morbidity attributed to infection-induced preterm birth.

Role of immunological factors in the pathophysiology and diagnosis of bipolar disorder: comparison with schizophrenia

Several lines of evidence point to the key role of neurobiological mechanisms and shared genetic background in schizophrenia and bipolar disorder. For both disorders, neurodevelopmental and neurodegenerative processes have been postulated to be relevant for the pathogenesis as well as dysregulation of immuno-inflammatory pathways. Inflammation is a complex biological response to harmful stimuli and it is mediated by cytokines cascades, cellular immune responses, oxidative factors and hormone regulation. Cytokines, in particular, are supposed to play a critical role in infectious and inflammatory processes, mediating the cross-talk between the brain and the immune system; they also possibly contribute to the development of the central nervous system. From this perspective, even though mixed results have been reported, it seems that both schizophrenia and bipolar disorder are associated with an imbalance in inflammatory cytokines; in fact, some of these could represent biological markers of illness and could be possible targets for pharmacological treatments. In light of these considerations, the purpose of the present paper was to provide a comprehensive and critical review of the existing literature about immunological abnormalities in bipolar disorder with particular attention to the similarities and differences with schizophrenia.

The efficacy of intravenous immunoglobulin on lipopolysaccharide-induced fetal brain inflammation in preterm rats

OBJECTIVE

Interleukin-1 is accepted as one of the major cytokines; it is involved in inflammatory processes and systemic fetal inflammatory response that is triggered by maternal lipopolysaccharide (LPS) injection. Because it is an antiinflammatory agent, we investigated (in the brain damage of rat pups) the role of intravenous immunoglobulin (IVIG) in decreasing interleukin-1 beta (IL-1β) expression and caspase 3 activity that was induced by maternal LPS administration.

STUDY DESIGN

Dams were divided into 3 groups. Pyrogen-free saline solution (NS) was administered intraperitoneally to group 1; LPS (0.3 mg/kg) suspension in NS was administered to groups 2 and 3 at 19 days of gestation. Two hours after the first injection, a second injection of NS was administered intravenously to group 1 (NS + NS), of IVIG was administered intravenously to group 2 (LPS + IVIG), and of NS was administered intravenously to group 3 (LPS + NS). Hysterectomy was performed in one-half of the dams 2 hours after the second injection and in the other one-half of the dams 22 hours after the second injection. Pups were delivered, and the brains were extracted just after delivery. IL-1β expression and caspase 3 activity were determined in brain tissues.

RESULTS

For the pups at 4 hours, the IL-1β expression of group 2 was significantly lower than groups 1 and 3. For the pups at 24 hours, the IL-1β expression of group 2 was significantly lower than group 3 but was similar to group 1. For the pups at 24 hours, caspase 3 activity of groups 1 and 2 were significantly lower than group 3.

CONCLUSION

Maternal IVIG administration decreased IL-1β expression and caspase 3 activity in the brain tissue of rat pups, which had been induced by maternal LPS-administration.