Systemic and local cytokine profiles in endotoxin-induced preterm parturition in mice

The Gordian knot of the immune-redox systems' interactions in psychosis

During the last decades the attempt to enlighten the pathobiological substrate of psychosis, from merely focusing on neurotransmitters, has expanded into new areas like the immune and redox systems. Indeed, the inflammatory hypothesis concerning psychosis etiopathology has exponentially grown with findings reflecting dysfunction/aberration of the immune/redox systems' effector components namely cytokines, chemokines, CRP, complement system, antibodies, pro-/anti-oxidants, oxidative stress byproducts just to name a few. Yet, we still lie far from comprehending the underlying cellular mechanisms, their causality directions, and the moderating/mediating parameters affecting these systems; let alone the inter-systemic (between immune and redox) interactions. Findings from preclinical studies on the stress field have provided evidence indicative of multifaceted interactions among the immune and redox components so tightly intertwined as a Gordian knot. Interestingly the literature concerning the interactions between these same systems in the context of psychosis appears minimal (if not absent) and ambiguous. This review attempts to draw a frame of the immune-redox systems' interactions starting from basic research on the stress field and expanding on clinical studies with cohorts with psychosis, hoping to instigate new avenues of research.

The fetal response to maternal inflammation is dependent upon maternal IL-6 in a murine model

BACKGROUND

The induction of maternal inflammation in mice leads to fetal injury that is believed to be IL-6 dependent. The fetal inflammatory response, defined by elevated fetal or amniotic fluid IL-6, has been described as a potential mechanism for subsequent fetal injury. The role of maternal IL-6 production and signaling in the fetal IL-6 response is currently unclear.

METHODS

Genetic and anti-IL-6 antibody strategies were used to systematically block the maternal IL-6 response during inflammation. Chorioamnionitis was induced using intraperitoneal injection of lipopolysaccharide (LPS) at mid gestation (E14.5) and late gestation (E18.5). This model was used in pregnant C57Bl/6 dams, IL6-/- dams, C57Bl/6 dams treated with anti-IL-6 (blocks both classical and trans-signaling) or anti-gp130 antibodies (blocks trans-signaling only) and IL6+/- dams. Six hours following LPS injection, maternal serum, placental tissue, amniotic fluid and fetal tissue or serum were collected. A bead-based multiplex assay was used to evaluate levels of IL-6, KC, IL-1β, TNF, IL-10, IL-22, IFN-γ, IL-13 and IL-17A.

RESULTS

Chorioamnionitis in C57Bl/6 dams was characterized by elevated maternal serum levels of IL-6, KC and IL-22 with litter loss during mid gestation. The fetal response to maternal inflammation in C57Bl/6 mice was primarily characterized by elevated levels of IL-6, KC and IL-22 in the placenta, amniotic fluid and fetus during both mid and late gestation. A global IL-6 knockout (IL6-/-) eradicated the maternal, placental, amniotic fluid and fetal IL-6 response to LPS during mid and late gestation and improved litter survival, while minimally influencing the KC or IL-22 responses. Blocking maternal classical IL-6 signaling in C57Bl/6 dams at the time of LPS exposure diminished the maternal, placental, amniotic fluid and fetal IL-6 response during mid and late gestation, while blocking maternal IL-6 trans-signaling only affected fetal IL-6 expression. To evaluate whether maternal IL-6 was crossing the placenta and reaching the fetus, IL-6+/- dams were utilized in the chorioamnionitis model. IL-6+/- dams mounted a systemic inflammatory response following injection with LPS, characterized by elevated IL-6, KC and IL-22. IL-6-/- pups born to IL6+/- dams had decreased amniotic fluid levels of IL-6 and undetectable levels of fetal IL-6 compared to IL-6+/+ littermate controls.

CONCLUSION

The fetal response to systemic maternal inflammation is dependent upon maternal IL-6 signaling, but maternal IL-6 is not crossing the placenta and reaching the fetus at detectable levels.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Composition of Vaginal Microbiota in Pregnant Women With Aerobic Vaginitis

Vaginal dysbiosis, such as bacterial vaginosis (BV) and aerobic vaginitis (AV), is an important cause of premature birth in pregnant women. However, there is very little research on vaginal microbial distribution in AV compared to that in BV. This study aimed to analyze the composition of the vaginal microbiota of pregnant women with AV using microbial community analysis and identify the causative organism using each criterion of the AV scoring system. Also, we compared the quantification of aerobic bacteria using quantitative polymerase chain reaction (qPCR) and their relative abundances (RA) using metagenomics. This prospective case–control study included 228 pregnant Korean women from our previous study. A wet mount test was conducted on 159 women to diagnose AV using the AV scoring system. Vaginal samples were analyzed using metagenomics, Gram staining for Nugent score determination, conventional culture, and qPCR for Staphylococcus spp., Streptococcus spp., and Enterobacteriaceae. The relative abundances (RAs) of eleven species showed significant differences among the three groups (Normal flora (NF), mild AV, and moderate AV). Three species including Lactobacillus crispatus were significantly lower in the AV groups than in the NF group, while eight species were higher in the AV groups, particularly moderate AV. The decrease in the RA of L. crispatus was common in three criteria of the AV scoring system (Lactobacillary, WBC, and background flora grades), while it did not show a significant difference among the three grade groups of the toxic leukocyte criterion. Also, the RAs of anaerobes, such as Gardnerella and Megasphaera, were higher in the AV groups, particularly moderate AV, while the RAs of aerobes were very low (RA < 0.01). Therefore, qPCR was performed for aerobes (Staphylococcus spp., Streptococcus spp., and Enterobacteriaceae); however, their quantification did not show a higher level in the AV groups when compared to that in the NF group. Therefore, AV might be affected by the RA of Lactobacillus spp. and the main anaerobes, such as Gardnerella spp. Activation of leukocytes under specific conditions might convert them to toxic leukocytes, despite high levels of L. crispatus. Thus, the pathogenesis of AV can be evaluated under such conditions.

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.

Preeclampsia and Neurodevelopmental Outcomes: Potential Pathogenic Roles for Inflammation and Oxidative Stress?

Preeclampsia (PE) is a common and serious hypertensive disorder of pregnancy that occurs in approximately 3-5% of first-time pregnancies and is a well-known leading cause of maternal and neonatal mortality and morbidity. In recent years, there has been accumulating evidence that in utero exposure to PE acts as an environmental risk factor for various neurodevelopmental disorders, particularly autism spectrum disorder and ADHD. At present, the mechanism(s) mediating this relationship are uncertain. In this review, we outline the most recent evidence implicating a causal role for PE exposure in the aetiology of various neurodevelopmental disorders and provide a novel interpretation of neuroanatomical alterations in PE-exposed offspring and how these relate to their sub-optimal neurodevelopmental trajectory. We then postulate that inflammation and oxidative stress, two prominent features of the pathophysiology of PE, are likely to play a major role in mediating this association. The increased inflammation in the maternal circulation, placenta and fetal circulation in PE expose the offspring to both prenatal maternal immune activation-a risk factor for neurodevelopmental disorders, which has been well-characterised in animal models-and directly higher concentrations of pro-inflammatory cytokines, which adversely affect neuronal development. Similarly, the exaggerated oxidative stress in the mother, placenta and foetus induces the placenta to secrete factors deleterious to neurons, and exposes the fetal brain to directly elevated oxidative stress and thus adversely affects neurodevelopmental processes. Finally, we describe the interplay between inflammation and oxidative stress in PE, and how both systems interact to potentially alter neurodevelopmental trajectory in exposed offspring.

The promise of placental extracellular vesicles: models and challenges for diagnosing placental dysfunction in utero†

Monitoring the health of a pregnancy is of utmost importance to both the fetus and the mother. The diagnosis of pregnancy complications typically occurs after the manifestation of symptoms, and limited preventative measures or effective treatments are available. Traditionally, pregnancy health is evaluated by analyzing maternal serum hormone levels, genetic testing, ultrasonographic imaging, and monitoring maternal symptoms. However, researchers have reported a difference in extracellular vesicle (EV) quantity and cargo between healthy and at-risk pregnancies. Thus, placental EVs (PEVs) may help to understand normal and aberrant placental development, monitor pregnancy health in terms of developing placental pathologies, and assess the impact of environmental influences, such as infection, on pregnancy. The diagnostic potential of PEVs could allow for earlier detection of pregnancy complications via noninvasive sampling and frequent monitoring. Understanding how PEVs serve as a means of communication with maternal cells and recognizing their potential utility as a readout of placental health have sparked a growing interest in basic and translational research. However, to date, PEV research with animal models lags behind human studies. The strength of animal pregnancy models is that they can be used to assess placental pathologies in conjunction with isolation of PEVs from fluid samples at different time points throughout gestation. Assessing PEV cargo in animals within normal and complicated pregnancies will accelerate the translation of PEV analysis into the clinic for potential use in prognostics. We propose that appropriate animal models of human pregnancy complications must be established in the PEV field.

Maternal regulation of inflammatory cues is required for induction of preterm birth

Infection-driven inflammation in pregnancy is a major cause of spontaneous preterm birth (PTB). Both systemic infection and bacterial ascension through the vagina/cervix to the amniotic cavity are strongly associated with PTB. However, the contribution of maternal or fetal inflammatory responses in the context of systemic or localized models of infection-driven PTB is not well defined. Here, using intraperitoneal or intraamniotic LPS challenge, we examined the necessity and sufficiency of maternal and fetal Toll-like receptor (TLR) 4 signaling in induction of inflammatory vigor and PTB. Both systemic and local LPS challenge promoted induction of inflammatory pathways in uteroplacental tissues and induced PTB. Restriction of TLR4 expression to the maternal compartment was sufficient for induction of LPS-driven PTB in either systemic or intraamniotic challenge models. In contrast, restriction of TLR4 expression to the fetal compartment failed to induce LPS-driven PTB. Vav1-Cre-mediated genetic deletion of TLR4 suggested a critical role for maternal immune cells in inflammation-driven PTB. Further, passive transfer of WT in vitro-derived macrophages and dendritic cells to TLR4-null gravid females was sufficient to induce an inflammatory response and drive PTB. Cumulatively, these findings highlight the critical role for maternal regulation of inflammatory cues in induction of inflammation-driven parturition.

Pregnancy-specific transcriptional changes upon endotoxin exposure in mice

Objectives Pregnant women are more susceptible to certain infections; however, this increased susceptibility is not fully understood. Herein, systems biology approaches were utilized to elucidate how pregnancy modulates tissue-specific host responses to a bacterial product, endotoxin. Methods Pregnant and non-pregnant mice were injected with endotoxin or saline on 16.5 days post coitum (n=8-11 per group). The uterus, cervix, liver, adrenal gland, kidney, lung, and brain were collected 12 h after injection and transcriptomes were measured using microarrays. Heatmaps and principal component analysis were used for visualization. Differentially expressed genes between groups were assessed using linear models that included interaction terms to determine whether the effect of infection differed with pregnancy status. Pathway analysis was conducted to interpret gene expression changes. Results We report herein a multi-organ atlas of the transcript perturbations in pregnant and non-pregnant mice in response to endotoxin. Pregnancy strongly modified the host responses to endotoxin in the uterus, cervix, and liver. In contrast, pregnancy had a milder effect on the host response to endotoxin in the adrenal gland, lung, and kidney. However, pregnancy did not drastically affect the host response to endotoxin in the brain. Conclusions Pregnancy imprints organ-specific host immune responses upon endotoxin exposure. These findings provide insight into the host-response against microbes during pregnancy.

The adoptive transfer of BCG-induced T lymphocytes contributes to hippocampal cell proliferation and tempers anxiety-like behavior in immune deficient mice

We previously have reported that neonatal Bacillus Calmette-Guerin (BCG) vaccination improves neurogenesis and behavior in early life through affecting the neuroimmune milieu in the brain, but it is uncertain whether activation phenotypes and functional changes in T lymphocytes shape brain development. Here, we studied the effects of BCG vaccination via the adoptive transfer of T lymphocytes from the BALB/c wild-type mice into naive mice. Our results show that mice adoptive BCG-induced lymphocytes (BCG->naive mice) showed anxiolytic and antidepressant-like performance when completing an elevated plus maze (EPM) test. Meanwhile, BCG->naive mice possess more cell proliferation and newborn neurons than PBS->naive and nude mice in the hippocampus. IFN-γ and IL-4 levels in the serum of BCG->naive mice also increased, while TNF-α and IL-1β levels were reduced relative to those of PBS->naive and nude mice. We further found that BCG->naive mice showed different repartition of CD4⁺ and CD8⁺ T cell to naive (CD62L⁺CD44^low), effector memory (CD62L⁻CD44^hi), central memory (CD62L⁺CD44^hi) and acute/activated effector (CD62L⁻CD44^low) cells in the spleen. Importantly, the adoptive transfer of BCG-induced T lymphocytes infiltrated into the dura mater and brain parenchyma of the nude mice. Activation phenotypes and functional changes in T lymphocytes are very likely to affect the neuroimmune milieu in the brain, and alterations in ratios of splenic CD4⁺ and CD8⁺ memory T cells may affect the expression of correlative cytokines in the serum, accounting for our behavioral results. We conclude thus that the adoptive transfer of BCG-induced T lymphocytes contributes to hippocampal cell proliferation and tempers anxiety-like behavior in immune deficient mice. Our work shows that BCG vaccination improves hippocampal cell proliferation outcomes and behaviors, likely as a result of splenic effector/memory T lymphocytes regulating the neuroimmune niche in the brain.

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

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

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

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

New models of lipopolysaccharide-induced implantation loss reveal insights into the inflammatory response

PROBLEM

Chronic endometritis, inflammation of the uterizzvvne lining caused by common gram-negative bacterial strains or mycoplasma, has been associated with unexplained implantation failure and infertility. However, limited models of bacteria-induced implantation loss exist to study the molecular changes that occur in vivo. The goal of this study was to provide a new resource to study the process of bacteria-induced inflammation and implantation loss utilizing common experimental models: C57Bl/6 mice and primary human endometrial stromal cells.

METHOD OF STUDY

Prior to implantation, mated C57Bl/6 females were administered vehicle (saline) or gram-negative bacterial lipopolysaccharide (LPS) at a range of concentrations by intraperitoneal injection. Implantation sites were counted, and uteri were harvested to evaluate the molecular changes that accompany LPS-mediated implantation loss. Primary human endometrial stromal cells were decidualized in vitro in the presence and absence of LPS. Total RNA and conditioned media were harvested to evaluate the expression of known decidualization-associated genes and various cytokines and chemokines.

RESULTS

Lipopolysaccharide treatment resulted in fewer implantation sites in mice, decreased expression of decidualization-associated genes, and altered expression and release of cytokines and chemokines. Immunohistological analysis of the uterus from LPS-exposed mice demonstrated increased apoptosis and decreased proliferation during decidualization.

CONCLUSION

Lipopolysaccharide exposure disrupted implantation and decidualization in mice and human endometrial stromal cells. This model could be used to study the pathophysiology of implantation failure in patients with chronic endometritis or to test potential therapeutic interventions.

Maternal immune activation: reporting guidelines to improve the rigor, reproducibility, and transparency of the model

The 2017 American College of Neuropychopharmacology (ACNP) conference hosted a Study Group on 4 December 2017, Establishing best practice guidelines to improve the rigor, reproducibility, and transparency of the maternal immune activation (MIA) animal model of neurodevelopmental abnormalities. The goals of this session were to (a) evaluate the current literature and establish a consensus on best practices to be implemented in MIA studies, (b) identify remaining research gaps warranting additional data collection and lend to the development of evidence-based best practice design, and (c) inform the MIA research community of these findings. During this session, there was a detailed discussion on the importance of validating immunogen doses and standardizing the general design (e.g., species, immunogenic compound used, housing) of our MIA models both within and across laboratories. The consensus of the study group was that data does not currently exist to support specific evidence-based model selection or methodological recommendations due to lack of consistency in reporting, and that this issue extends to other inflammatory models of neurodevelopmental abnormalities. This launched a call to establish a reporting checklist focusing on validation, implementation, and transparency modeled on the ARRIVE Guidelines and CONSORT (scientific reporting guidelines for animal and clinical research, respectively). Here we provide a summary of the discussions in addition to a suggested checklist of reporting guidelines needed to improve the rigor and reproducibility of this valuable translational model, which can be adapted and applied to other animal models as well.

Dietary omega-3 deficiency exacerbates inflammation and reveals spatial memory deficits in mice exposed to lipopolysaccharide during gestation

Maternal immune activation (MIA) is a common environmental insult on the developing brain and represents a risk factor for neurodevelopmental disorders. Animal models of in utero inflammation further revealed a causal link between maternal inflammatory activation during pregnancy and behavioural impairment relevant to neurodevelopmental disorders in the offspring. Accumulating evidence point out that proinflammatory cytokines produced both in the maternal and fetal compartments are responsible for social, cognitive and emotional behavioral deficits in the offspring. Polyunsaturated fatty acids (PUFAs) are essential fatty acids with potent immunomodulatory activities. PUFAs and their bioactive derivatives can promote or inhibit many aspects of the immune and inflammatory response. PUFAs of the n-3 series ('n-3 PUFAs', also known as omega-3) exhibit anti-inflammatory/pro-resolution properties and promote immune functions, while PUFAs of the n-6 series ('n-6 PUFAs' or omega-6) favor pro-inflammatory responses. The present study aimed at providing insight into the effects of n-3 PUFAs on the consequences of MIA on brain development. We hypothesized that a reduction in n-3 PUFAs exacerbates both maternal and fetal inflammatory responses to MIA and later-life defects in memory in the offspring. Based on a lipopolysaccharide (LPS) model of MIA (LPS injection at embryonic day 17), we showed that n-3 PUFA deficiency 1) alters fatty acid composition of the fetal and adult offspring brain; 2) exacerbates maternal and fetal inflammatory processes with no significant alteration of microglia phenotype, and 3) induces spatial memory deficits in the adult offspring. We also showed a strong negative correlation between brain content in n-3 PUFA and cytokine production in MIA-exposed fetuses. Overall, our study is the first to address the deleterious effects of n-3 PUFA deficiency on brain lipid composition, inflammation and memory performances in MIA-exposed animals and indicates that it should be considered as a potent environmental risk factor for the apparition of neurodevelopmental disorders.

Fetal Membrane Inflammation Induces Preterm Birth Via Toll-Like Receptor 2 in Mice With Chronic Gingivitis

Inflammation is associated with preterm birth. We previously described a mouse model of chronic inflammation-induced preterm birth after dental Porphyromonas gingivalis infection. The aim of this study was to employ this model system to investigate the mechanisms through which enhanced uterine contractility induces preterm birth. Messenger RNA (mRNA) encoding contraction-associated proteins, such as oxytocin receptors, was measured at various gestational time points by real-time polymerase chain reaction (PCR). Spontaneous and oxytocin-induced uterine contractile activity at gestational day 18 was assessed using a tissue organ bath. The expression levels of Toll-like receptor 2 (TLR2), TLR4, cyclooxygenase (COX)-2, nuclear factor-kappa B (NF-κB) p65, and p38 mitogen-activated protein kinase (MAPK) on gestational day 18 were also determined by real-time PCR or Western blotting. Messenger RNA encoding contraction-associated proteins was increased at gestational day 18, and the spontaneous contractile activity (1.6-fold greater area under the contraction curve) and sensitivity to oxytocin (EC₅₀: 8.8 nM vs 2.2 nM) were enhanced in the P gingivalis group compared to those in the control group. In the P gingivalis group, COX-2 mRNA expression was not elevated in the placenta or myometrium but was upregulated 2.3-fold in the fetal membrane. The TLR2 mRNA levels in the fetal membrane were 2.7-fold higher in the P gingivalis group, whereas TLR4 levels were not elevated. Activation of the NF-κB p65 and p38 MAPK pathways was enhanced in the fetal membrane of the P gingivalis group. Thus, in mice with chronic dental P gingivalis infection, TLR2-induced inflammation in the fetal membrane leads to upregulation of uterine contractility, leading to preterm birth.

Runt-related transcription factor 1 (RUNX1) deficiency attenuates inflammation-induced pro-inflammatory and pro-labour mediators in myometrium

Identifying new targets that regulate myometrial activation are required to develop effective treatments to stop preterm labor. Inflammation, which can be induced by sterile or infective insults, plays a role in initiating and maintaining uterine contractions. Several high throughput transcription screening studies have identified an upregulation of runt-related transcription factor 1 (RUNX1) mRNA expression in myometrium with labor. The role of RUNX1 in labor, however, is not known. We report increased RUNX1 during late gestation which was further augmented in labor, suggesting that RUNX1 may be involved in the transition of the myometrium from a quiescent into a contractile state in preparation for labor. By inhibiting the expression of RUNX1, we have established that RUNX1 induces the expression of pro-inflammatory cytokines, chemokines, adhesion molecules, contraction-associated proteins OXR and PTGFR, the uterotonic PGF_2α, and the ECM remodelling enzyme MMP9. Targeting RUNX1 may be a novel approach to prevent preterm labor.

Expression and regulation of metallothioneins in myometrium and fetal membranes

PROBLEM

Metallothioneins (MTs) play important roles in regulating oxidative stress, inflammation, and hormone signaling. These processes play a major role in labor at term and preterm. The aims of this study were to characterize (a) temporal- and labor-associated changes and (b) the effect of pro-inflammatory and pro-labor insults on the expression of MT1 isoforms, MT2A, MT3, and MT4 in fetal membranes and myometrium.

METHOD OF STUDY

The expression of MTs was assessed in fetal membranes and myometrium from nonlaboring and laboring women at preterm and term by RT-qPCR. Tissue explants were used to assess the effect of pro-inflammatory cytokines and Toll-like receptor (TLR) ligands on the expression of MTs in fetal membranes and myometrium.

RESULTS

In fetal membranes, the expression of MT1A, MT1E, MT1F, MT1X, and MT2A was higher at term compared with preterm. Preterm labor and preterm histological chorioamnionitis were associated with increased expression of MT1A, MT1G, MT1M, MT1X, MT2A, and MT3. Term labor was associated with increased expression of MT1A, MT1F, MT1X, MT2A, and MT3 in fetal membranes and expression of MT1A, MT1E, MT1F, MT1G, MT1M, MT1X, MT2A, and MT3 in myometrium. Pro-inflammatory cytokines and TLR ligands increased the expression of MT1A, MT1E, MT1F, MT1G, MT1H, MT1X, and MT2A in fetal membranes and myometrium.

CONCLUSION

Temporal-, labor-, and infection-associated increases in MT1 isoforms, MT2A, and MT3 have been observed in fetal membranes and/or myometrium. Furthermore, pro-inflammatory cytokines and bacterial and viral products increased the expression of MT1 isoforms, MT2A, MT3, and MT4 mRNA expression in fetal membranes and myometrium.

Disruption of female reproductive function by endotoxins

Endotoxemia can be caused by obesity, environmental chemical exposure, abiotic stressors and bacterial infection. Circumstances that deleteriously impact intestinal barrier integrity can induce endotoxemia, and controlled experiments have identified negative impacts of lipopolysaccharide (LPS; an endotoxin mimetic) on folliculogenesis, puberty onset, estrus behavior, ovulation, meiotic competence, luteal function and ovarian steroidogenesis. In addition, neonatal LPS exposures have transgenerational female reproductive impacts, raising concern about early life contacts to this endogenous reproductive toxicant. Aims of this review are to identify physiological stressors causing endotoxemia, to highlight potential mechanism(s) by which LPS compromises female reproduction and identify knowledge gaps regarding how acute and/or metabolic endotoxemia influence(s) female reproduction.

Beyond infection - Maternal immune activation by environmental factors, microglial development, and relevance for autism spectrum disorders

Immune molecules such as cytokines and chemokines and the cells that produce them within the brain, notably microglia, are critical for normal brain development. This recognition has in recent years led to the working hypothesis that inflammatory events during pregnancy, e.g. in response to infection, may disrupt the normal expression of immune molecules during critical stages of neural development and thereby contribute to the risk for neurodevelopmental disorders such as autism spectrum disorder (ASD). This hypothesis has in large part been shepherded by the work of Dr. Paul Patterson and colleagues, which has elegantly demonstrated that a single viral infection or injection of a viral mimetic to pregnant mice significantly and persistently impacts offspring immune and nervous system function, changes that underlie ASD-like behavioral dysfunction including social and communication deficits. Subsequent studies by many labs - in humans and in non-human animal models - have supported the hypothesis that ongoing disrupted immune molecule expression and/or neuroinflammation contributes to at least a significant subset of ASD. The heterogeneous clinical and biological phenotypes observed in ASD strongly suggest that in genetically susceptible individuals, environmental risk factors combine or synergize to create a tipping or threshold point for dysfunction. Importantly, animal studies showing a link between maternal immune activation (MIA) and ASD-like outcomes in offspring involve different species and diverse environmental factors associated with ASD in humans, beyond infection, including toxin exposures, maternal stress, and maternal obesity, all of which impact inflammatory or immune pathways. The goal of this review is to highlight the broader implications of Dr. Patterson's work for the field of autism, with a focus on the impact that MIA by diverse environmental factors has on fetal brain development, immune system development, and the pathophysiology of ASD.

Early-Life Nutritional Programming of Cognition-The Fundamental Role of Epigenetic Mechanisms in Mediating the Relation between Early-Life Environment and Learning and Memory Process

The perinatal period is a window of heightened plasticity that lays the groundwork for future anatomic, physiologic, and behavioral outcomes. During this time, maternal diet plays a pivotal role in the maturation of vital organs and the establishment of neuronal connections. However, when perinatal nutrition is either lacking in specific micro- and macronutrients or overloaded with excess calories, the consequences can be devastating and long lasting. The brain is particularly sensitive to perinatal insults, with several neurologic and psychiatric disorders having been linked to a poor in utero environment. Diseases characterized by learning and memory impairments, such as autism, schizophrenia, and Alzheimer disease, are hypothesized to be attributed in part to environmental factors, and evidence suggests that the etiology of these conditions may date back to very early life. In this review, we discuss the role of the early-life diet in shaping cognitive outcomes in offspring. We explore the endocrine and immune mechanisms responsible for these phenotypes and discuss how these systemic factors converge to change the brain's epigenetic landscape and regulate learning and memory across the lifespan. Through understanding the maternal programming of cognition, critical steps may be taken toward preventing and treating diseases that compromise learning and memory.

Intra-amniotic administration of lipopolysaccharide induces spontaneous preterm labor and birth in the absence of a body temperature change

OBJECTIVE

Intra-amniotic infection is associated with spontaneous preterm labor. In most cases, the infection is subclinical and bacteria are detected in the amniotic cavity rather than in the chorioamniotic membranes. The aims of this study were to establish a model of intra-amniotic lipopolysaccharide (LPS)-induced preterm labor/birth that resembles the subclinical syndrome and to compare this model to two established models of LPS-induced preterm labor/birth.

METHODS

Pregnant B6 mice received an intra-amniotic, intra-uterine, or intra-peritoneal injection of LPS (100 ng/amniotic sac, 15 μg/25 μL, and 15 μg/200 μL respectively) or PBS (control). Following injection, body temperature (every two hours for a 12-h period), gestational age, and the rate of preterm labor/birth were recorded.

RESULTS

An intra-amniotic injection of LPS resulted in preterm labor/birth [LPS 80 ± 24.79% (8/10) versus PBS 0% (0/8); p = 0.001] without causing maternal hypothermia. Intra-peritoneal [LPS 100% (8/8) versus PBS 0% (0/8); p < 0.001)] and intra-uterine [LPS 100% (8/8) versus PBS 28.57 ± 33.47% (2/7); p =0 .007] injections of LPS induced preterm labor/birth; yet, maternal hypothermia was observed.

CONCLUSION

Intra-amniotic injection of LPS induces preterm labor/birth in the absence of a body temperature change, which resembles the subclinical syndrome.

A Role for the Inflammasome in Spontaneous Labor at Term with Acute Histologic Chorioamnionitis

Inflammasomes are cytosolic signaling platforms that regulate the activation of caspase (CASP)-1, which induces the maturation of interleukin (IL)-1β and IL-18. Herein, we determined whether the chorioamniotic membranes from women in spontaneous labor at term with acute histologic chorioamnionitis express major inflammasome components and whether these changes are associated with the activation of CASP-1 and CASP-4 and the release of mature IL-1β and IL-18. When comparing the chorioamniotic membranes from women in spontaneous labor at term with acute histologic chorioamnionitis to those without this placental lesion, we found that (1) the messenger RNA (mRNA) abundance of NLR family pyrin domain containing 3 ( NLRP3), NLR family CARD domain containing 4 ( NLRC4), absent in melanoma 2 ( AIM2), and nucleotide binding oligomerization domain 2 ( NOD2) was higher; (2) the NLRP3 and NLRC4 protein quantities were increased; (3) the mRNA and protein expressions of CASP-1 and its active forms were greater; (4) CASP-4 was increased at the mRNA level only; (5) the mRNA and protein expressions of IL-1β and its mature form were higher; and (6) a modest increase in the total protein concentration and abundance of the mature form of IL-18 was observed. In vitro incubation of the chorioamniotic membranes with the CASP-1 inhibitor, VX765, decreased the release of endotoxin-induced IL-1β and IL-18 (2-fold) but not IL-6 or tumor necrosis factor α. In conclusion, spontaneous labor at term with acute histologic chorioamnionitis is characterized by an upregulation of inflammasome components which, in turn, may participate in the activation of CASP-1 and lead to the release of mature IL-1β by the chorioamniotic membranes. These results support a role for the inflammasome in the mechanisms responsible for spontaneous labor at term with acute histologic chorioamnionitis.

Periodontitis, cardiovascular disease and pregnancy outcome--focal infection revisited?

Over the last two decades there has been a renewed interest around the possible effects of periodontal disease on both cardiovascular health and pregnancy outcome (among other diseases), a topic which has interested science for hundreds of years. These have led to a range of studies, workshops and consensus documents being published, with corresponding coverage in general and professional media. In this article the authors summarise the history and supporting theories behind such associations, whether clinical studies have been able to confirm these and what this might mean for general practitioners who are questioned on this topic by patients.

An imbalance between innate and adaptive immune cells at the maternal-fetal interface occurs prior to endotoxin-induced preterm birth

Preterm birth (PTB) is the leading cause of neonatal morbidity and mortality worldwide. A transition from an anti-inflammatory state to a pro-inflammatory state in the mother and at the maternal-fetal interface has been implicated in the pathophysiology of microbial-induced preterm labor. However, it is unclear which immune cells mediate this transition. We hypothesized that an imbalance between innate and adaptive immune cells at the maternal-fetal interface will occur prior to microbial-induced preterm labor. Using an established murine model of endotoxin-induced PTB, our results demonstrate that prior to delivery there is a reduction of CD4+ regulatory T cells (Tregs) in the uterine tissues. This reduction is neither linked to a diminished number of Tregs in the spleen, nor to an impaired production of IL10, CCL17, or CCL22 by the uterine tissues. Endotoxin administration to pregnant mice does not alter effector CD4+ T cells at the maternal-fetal interface. However, it causes an imbalance between Tregs (CD4+ and CD8+), effector CD8+ T cells, and Th17 cells in the spleen. In addition, endotoxin administration to pregnant mice leads to an excessive production of CCL2, CCL3, CCL17, and CCL22 by the uterine tissues as well as abundant neutrophils. This imbalance in the uterine microenvironment is accompanied by scarce APC-like cells such as macrophages and MHC II+ neutrophils. Collectively, these results demonstrate that endotoxin administration to pregnant mice causes an imbalance between innate and adaptive immune cells at the maternal-fetal interface.

A Cross-Species Analysis of Animal Models for the Investigation of Preterm Birth Mechanisms

BACKGROUND

Spontaneous preterm birth is the leading cause of neonatal morbidity and mortality worldwide. The ability to examine the exact mechanisms underlying this syndrome in humans is limited. Therefore, the study of animal models is critical to unraveling the key physiologic mechanisms that control the timing of birth. The purpose of this review is to facilitate enhanced assimilation of the literature on animal models of preterm birth by a broad range of investigators.

METHODS

Using classical systematic and informatics search techniques of the available literature through 2012, a database of intact animal models was generated. Research librarians generated a list of articles using multiple databases. From these articles, a comprehensive list of Medical Subject Headings (MeSH) was created. Using mathematical modeling, significant MeSH descriptors were determined, and a MEDLINE search algorithm was created. The articles were reviewed for mechanism of labor induction categorized by species.

RESULTS

Existing animal models of preterm birth comprise specific interventions to induce preterm birth, as no animal model was identified that exhibits natural spontaneous preterm birth at an incidence comparable to that of the humans. A search algorithm was developed which when used results in a comprehensive list of agents used to induce preterm delivery in a host of animal species. The evolution of 3 specific animal models--sheep, mice, and rats--has demonstrated a clear shift in focus in the literature from endocrine to inflammatory agents of preterm birth induction.

CONCLUSION

The process of developing a search algorithm to provide efficient access to information on animal models of preterm birth illustrates the need for a more precise organization of the literature to allow the investigator to focus on distinctly maternal versus fetal outcomes.

An M1-like Macrophage Polarization in Decidual Tissue during Spontaneous Preterm Labor That Is Attenuated by Rosiglitazone Treatment

Decidual macrophages are implicated in the local inflammatory response that accompanies spontaneous preterm labor/birth; however, their role is poorly understood. We hypothesized that decidual macrophages undergo a proinflammatory (M1) polarization during spontaneous preterm labor and that PPARγ activation via rosiglitazone (RSG) would attenuate the macrophage-mediated inflammatory response, preventing preterm birth. In this study, we show that: 1) decidual macrophages undergo an M1-like polarization during spontaneous term and preterm labor; 2) anti-inflammatory (M2)-like macrophages are more abundant than M1-like macrophages in decidual tissue; 3) decidual M2-like macrophages are reduced in preterm pregnancies compared with term pregnancies, regardless of the presence of labor; 4) decidual macrophages express high levels of TNF and IL-12 but low levels of peroxisome proliferator-activated receptor γ (PPARγ) during spontaneous preterm labor; 5) decidual macrophages from women who underwent spontaneous preterm labor display plasticity by M1↔M2 polarization in vitro; 6) incubation with RSG reduces the expression of TNF and IL-12 in decidual macrophages from women who underwent spontaneous preterm labor; and 7) treatment with RSG reduces the rate of LPS-induced preterm birth and improves neonatal outcomes by reducing the systemic proinflammatory response and downregulating mRNA and protein expression of NF-κB, TNF, and IL-10 in decidual and myometrial macrophages in C57BL/6J mice. In summary, we demonstrated that decidual M1-like macrophages are associated with spontaneous preterm labor and that PPARγ activation via RSG can attenuate the macrophage-mediated proinflammatory response, preventing preterm birth and improving neonatal outcomes. These findings suggest that the PPARγ pathway is a new molecular target for future preventative strategies for spontaneous preterm labor/birth.

Enhanced Expression of Contractile-Associated Proteins and Ion Channels in Preterm Delivery Model Mice With Chronic Odontogenic Porphyromonas Gingivalis Infection

Inflammation and infection have been reported to induce preterm delivery. We have studied the relationship between inflammation and various ion channels, including the L-type Ca(2+) channel and P2X7 receptor, during acute inflammation of the pregnant rat uterus induced by lipopolysaccharides. Recently, we found that mice with odontogenic Porphyromonas gingivalis (P.g, an important odontogenic pathogen) infection delivered at day 18.3 of gestation (vs. day 20.5 in normal mice). The purpose of this study was to investigate the expression of myometrial contractile-associated proteins inducing contractions and confirm that these mice are useful as a model for preterm delivery induced by chronic inflammation. We examined the expression of the oxytocin receptor, connexin 43, prostaglandin F receptors, L-type Ca(2+) channel, and P2X7 receptor in the myometrium at day 18 of gestation by real-time PCR and western blot analyses. We also measured TNF-α and IL-1β levels in the blood serum, placenta, fetal membrane and myometrium on the same day. mRNA expression of the oxytocin receptor, connexin 43, prostaglandin F receptors, L-type Ca(2+) channel, and P2X7 receptor was elevated by 5.4, 3.2, 2.4, 2.5, and 1.7 fold, respectively, in the P.g-infected mice. Protein levels of the oxytocin receptor and connexin 43 also increased. Serum levels of TNF-α and IL-1β were elevated, showing that systemic inflammation continued during pregnancy. IL-1β levels in the placenta and fetal membrane also increased, suggesting inflammatory reactions were induced. Thus, mice with odontogenic infection may be useful as a model of chronic inflammation-induced preterm delivery.

About one-half of early spontaneous preterm deliveries can be identified by a rapid matrix metalloproteinase-8 (MMP-8) bedside test at the time of mid-trimester genetic amniocentesis

OBJECTIVE

Mid-trimester amniocentesis continues to be used for the prenatal diagnosis of chromosomal anomalies and other genetic disorders. Analysis of amniotic fluid obtained at the time of mid-trimester genetic amniocentesis identifies those patients who are at risk for early spontaneous preterm delivery. This is based on a solid body of evidence that found subclinical intra-amniotic inflammation/infection to be causally linked to early spontaneous preterm birth. Although several biomarkers have been proposed to identify intra-amniotic inflammation, the accumulated data suggest that the determination of amniotic fluid matrix metalloproteinase-8 (MMP-8), or neutrophil collagenase, is a powerful predictor of spontaneous preterm delivery. MMP-8 is released by inflammatory cells in response to microbial products or "danger signals". A rapid point-of-care test has been developed to determine MMP-8 at the bedside within 20 min, and without the requirement of laboratory equipment. The objective of this study was to determine whether an elevation of MMP-8 in the amniotic fluid, measured by a rapid point-of-care test, can identify those patients at risk for spontaneous preterm delivery after a mid-trimester genetic amniocentesis.

STUDY DESIGN

A case-control study was designed to obtain amniotic fluid from asymptomatic singleton pregnant women who underwent mid-trimester genetic amniocentesis. An MMP-8 bedside test was performed to analyze the amniotic fluid of 64 patients with early spontaneous preterm delivery (<30 weeks) and 128 matched controls with normal pregnancy outcomes.

RESULTS

(1) The MMP-8 bedside test (Yoon's MMP-8 Check™) was positive in 42.2% (27/64) of patients with spontaneous preterm delivery but in none (0/128) of the control cases (p < 0.001); (2) the MMP-8 bedside test had a sensitivity of 42.2%, and a specificity of 100% in the prediction of spontaneous preterm delivery (<30 weeks) following a mid-trimester genetic amniocentesis; and (3) among the patients with spontaneous preterm delivery, those with a positive MMP-8 bedside test had a significantly higher rate of spontaneous delivery within 2 weeks and 4 weeks of an amniocentesis [40.7% (11/27) versus 5.4% (2/37); 63.0% (17/27) versus 24.3% (9/37)] and a shorter interval-to-delivery period than those with a negative test [interval-to-delivery: median (range), 16 d (0-95 d) versus 42 d (2-91 d); p < 0.05 for each].

CONCLUSION

We conclude that 42% of patients with an early spontaneous preterm delivery (< 30 weeks) could be identified by a rapid MMP-8 bedside test at the time of their mid-trimester genetic amniocentesis. The MMP-8 bedside test is a powerful predictor of early spontaneous preterm birth in asymptomatic pregnant women.

Gastric fluid versus amniotic fluid analysis for the identification of intra-amniotic infection due to Ureaplasma species

OBJECTIVE

Early neonatal sepsis is often due to intra-amniotic infection. The stomach of the neonate contains fluid swallowed before and during delivery. The presence of bacteria as well as neutrophils detected by culture or Gram stain of the gastric fluid during the first day of life is suggestive of exposure to bacteria or inflammation. We undertook this study to determine the relationship between gastric fluid analysis and amniotic fluid obtained by transabdominal amniocentesis in the detection of Ureaplasma species, the most frequent microorganisms responsible for intra-amniotic infection.

MATERIALS AND METHODS

The study population consisted of 100 singleton pregnant women who delivered preterm neonates (<35 weeks) within 7 days of amniocentesis. Gastric fluid of newborns was obtained by nasogastric intubation on the day of birth. Amniotic fluid and gastric fluid were cultured for genital Mycoplasmas, and polymerase chain reaction (PCR) for Ureaplasma species was performed. Intra-amniotic inflammation was defined as an elevated amniotic fluid matrix metalloproteinase-8 concentration (>23 ng/mL).

RESULTS

(1) Ureaplasma species were detected by culture or PCR in 18% (18/100) of amniotic fluid samples and in 5% (5/100) of gastric fluid samples; (2) among the amniotic fluid cases positive for Ureaplasma species, these microorganisms were identified in 27.8% (5/18) of gastric fluid samples; (3) none of the cases negative for Ureaplasma species in the amniotic fluid were found to be positive for these microorganisms in the gastric fluid; (4) patients with amniotic fluid positive for Ureaplasma species but with gastric fluid negative for these microorganisms had a significantly higher rate of intra-amniotic inflammation, acute histologic chorioamnionitis, and neonatal death than those with both amniotic fluid and gastric fluid negative for Ureaplasma species; and (5) no significant differences were observed in the rate of intra-amniotic inflammation, acute histologic chorioamnionitis, and neonatal death between patients with amniotic fluid positive for Ureaplasma species but with gastric fluid negative for these microorganisms and those with both amniotic fluid and gastric fluid positive for Ureaplasma species.

CONCLUSIONS

Gastric fluid analysis has 100% specificity in the identification of intra-amniotic infection with Ureaplasma species. However, the detection of Ureaplasma species by culture or PCR in the gastric fluid of neonates at birth did not identify these microorganisms in two-thirds of cases with microbial invasion of the amniotic cavity. Thus, amniotic fluid analysis is superior to that of gastric fluid in the identification of intra-amniotic infection.

A new antibiotic regimen treats and prevents intra-amniotic inflammation/infection in patients with preterm PROM

OBJECTIVES

To determine whether a new antibiotic regimen could reduce the frequency of intra-amniotic inflammation/infection in patients with preterm PROM.

STUDY DESIGN

This retrospective cohort study was conducted to evaluate the effect of antibiotics on the frequency of intra-amniotic inflammation/infection based on the results of follow-up transabdominal amniocenteses from 89 patients diagnosed with preterm PROM who underwent serial amniocenteses. From 1993-2003, ampicillin and/or cephalosporins or a combination was used ("regimen 1"). A new regimen (ceftriaxone, clarithromycin and metronidazole) was used from 2003-2012 ("regimen 2"). Amniotic fluid was cultured and matrix metalloproteinase-8 (MMP-8) concentrations were measured.

RESULTS

(1) The rates of intra-amniotic inflammation and intra-amniotic inflammation/infection in patients who received regimen 2 decreased during treatment from 68.8% to 52.1% and from 75% to 54.2%, respectively. In contrast, in patients who received regimen 1, the frequency of intra-amniotic inflammation and infection/inflammation increased during treatment (31.7% to 55% and 34.1% to 58.5%, respectively); and (2) intra-amniotic inflammation/infection was eradicated in 33.3% of patients who received regimen 2, but in none who received regimen 1.

CONCLUSION

The administration of ceftriaxone, clarithromycin and metronidazole was associated with a more successful eradication of intra-amniotic inflammation/infection and prevented secondary intra-amniotic inflammation/infection more frequently than an antibiotic regimen which included ampicillin and/or cephalosporins in patients with preterm PROM.

A critical role of interleukin-1 in preterm labor

Preterm birth (PTB) is a leading cause of neonatal mortality and morbidity worldwide, and represents a heavy economic and social burden. Despite its broad etiology, PTB has been firmly linked to inflammatory processes. Pro-inflammatory cytokines are produced in gestational tissues in response to stressors and can prematurely induce uterine activation, which precedes the onset of preterm labor. Of all cytokines implicated, interleukin (IL)-1 has been largely studied, revealing a central role in preterm labor. However, currently approved IL-1-targeting therapies have failed to show expected efficacy in pre-clinical studies of preterm labor. Herein, we (a) summarize animal and human studies in which IL-1 or IL-1-targeting therapeutics are implicated with preterm labor, (b) focus on novel IL-1-targeting therapies and diagnostic tests, and (c) develop the case for commercialization and translation means to hasten their development.

Advances in the Prevention of Infection-Related Preterm Birth

Infection-related preterm birth (PTB) is more common at early gestational ages and is associated with major neonatal mortality and morbidity. Abnormal genital tract microflora in early pregnancy predicts late miscarriage and early PTB. Accordingly, it is logical to consider antibiotics as an intervention. Unfortunately, the conclusions of systematic reviews and meta-analyses (SR&MAs) carried out in an attempt to explain the confusion over the heterogeneity of individual studies are flawed by the fact that undue reliance was placed on studies which: (a) had a suboptimal choice of antibiotic (mainly metronidazole) or used antibiotics not recommended for the treatment of bacterial vaginosis (BV) or BV-related organisms; (b) used antibiotics too late in pregnancy to influence outcome (23–27 weeks); and (c) included women whose risk of PTB was not due to abnormal genital tract colonization and hence unlikely to respond to antibiotics. These risks included: (a) previous PTB of indeterminate etiology; (b) low weight/body mass index; or (c) detection of fetal fibronectin, ureaplasmas, Group B streptococcus or Trichomonas vaginalis). While individual studies have found benefit of antibiotic intervention for the prevention of PTB, in meta-analyses these effects have been negated by large methodologically flawed studies with negative results. As a result, many clinicians think that any antibiotic given at any time in pregnancy to any woman at risk of PTB will cause more harm than good. Recently, a more focused SR&MA has demonstrated that antibiotics active against BV-related organisms, used in women whose risk of PTB is due to abnormal microflora, and used early in pregnancy before irreversible inflammatory damage has occurred, can reduce the rate of PTB. This review presents those data, the background and attempts to explain the confusion using new information from culture-independent molecular-based techniques. It also gives guidance on the structure of putative future antibiotic intervention studies.

Acute chorioamnionitis and funisitis: definition, pathologic features, and clinical significance

Acute inflammatory lesions of the placenta consist of diffuse infiltration of neutrophils at different sites in the organ. These lesions include acute chorioamnionitis, funisitis, and chorionic vasculitis and represent a host response (maternal or fetal) to a chemotactic gradient in the amniotic cavity. While acute chorioamnionitis is evidence of a maternal host response, funisitis and chorionic vasculitis represent fetal inflammatory responses. Intraamniotic infection generally has been considered to be the cause of acute chorioamnionitis and funisitis; however, recent evidence indicates that "sterile" intraamniotic inflammation, which occurs in the absence of demonstrable microorganisms induced by "danger signals," is frequently associated with these lesions. In the context of intraamniotic infection, chemokines (such as interleukin-8 and granulocyte chemotactic protein) establish a gradient that favors the migration of neutrophils from the maternal or fetal circulation into the chorioamniotic membranes or umbilical cord, respectively. Danger signals that are released during the course of cellular stress or cell death can also induce the release of neutrophil chemokines. The prevalence of chorioamnionitis is a function of gestational age at birth, and present in 3-5% of term placentas and in 94% of placentas delivered at 21-24 weeks of gestation. The frequency is higher in patients with spontaneous labor, preterm labor, clinical chorioamnionitis (preterm or term), or ruptured membranes. Funisitis and chorionic vasculitis are the hallmarks of the fetal inflammatory response syndrome, a condition characterized by an elevation in the fetal plasma concentration of interleukin-6, and associated with the impending onset of preterm labor, a higher rate of neonatal morbidity (after adjustment for gestational age), and multiorgan fetal involvement. This syndrome is the counterpart of the systemic inflammatory response syndrome in adults: a risk factor for short- and long-term complications (ie, sterile inflammation in fetuses, neonatal sepsis, bronchopulmonary dysplasia, periventricular leukomalacia, and cerebral palsy). This article reviews the definition, pathogenesis, grading and staging, and clinical significance of the most common lesions in placental disease. Illustrations of the lesions and diagrams of the mechanisms of disease are provided.

Inflammatory Markers Related to Microbial Translocation Among HIV-Infected Pregnant Women: A Risk Factor of Preterm Delivery

BACKGROUND

This study was performed to assess the role of lipopolysaccharide modulators as a marker of microbial translocation among human immunodeficiency virus (HIV)-infected women during pregnancy and to evaluate their association with preterm delivery.

METHODS

The study had a prospective cohort design and was performed at the Hospital Clínic in Barcelona, Spain. Thirty-six pregnant women with and 36 without HIV infection, matched on the basis of age and parity, were included. Maternal blood samples were obtained during the first trimester, during the third trimester, and at delivery. Levels of soluble CD14 (sCD14), human lipopolysaccharide-binding protein (LBP), immunoglobulin M endotoxin core antibodies to lipopolysaccharide (EndoCAb), and interleukin 6 (IL-6) were determined. Fetal cord blood levels of sCD14, LBP, and IL-6 were determined. Results were compared between groups.

RESULTS

First trimester sCD14 and LBP levels and third trimester sCD14 levels were significantly higher in the HIV-infected group. HIV-infected women with preterm births and spontaneous preterm births had significantly increased levels of sCD14 throughout pregnancy and significantly increased levels of LBP during the first trimester, compared with HIV-infected women with delivery at term or with HIV-negative women. On multivariate analysis, an independent association was observed between first trimester sCD14 levels and preterm delivery among HIV-infected women.

CONCLUSIONS

This is the first study to assess inflammatory markers related to microbial translocation during pregnancy among HIV-infected women. Higher levels of sCD14 and LBP were observed in HIV-infected pregnant women and were associated with preterm delivery.

Sterile intra-amniotic inflammation in asymptomatic patients with a sonographic short cervix: prevalence and clinical significance

OBJECTIVE

To determine the frequency and clinical significance of sterile and microbial-associated intra-amniotic inflammation in asymptomatic patients with a sonographic short cervix.

METHODS

Amniotic fluid (AF) samples obtained by transabdominal amniocentesis from 231 asymptomatic women with a sonographic short cervix [cervical length (CL) ≤25 mm] were analyzed using cultivation techniques (for aerobic and anaerobic as well as genital mycoplasmas) and broad-range polymerase chain reaction (PCR) coupled with electrospray ionization mass spectrometry (PCR/ESI-MS). The frequency and magnitude of intra-amniotic inflammation [defined as an AF interleukin (IL)-6 concentration ≥2.6 ng/mL], acute histologic placental inflammation, spontaneous preterm delivery (sPTD), and the amniocentesis-to-delivery interval were examined according to the results of AF cultures, PCR/ESI-MS and AF IL-6 concentrations.

RESULTS

Ten percent (24/231) of patients with a sonographic short cervix had sterile intra-amniotic inflammation (an elevated AF IL-6 concentration without evidence of microorganisms using cultivation and molecular methods). Sterile intra-amniotic inflammation was significantly more frequent than microbial-associated intra-amniotic inflammation [10.4% (24/231) versus 2.2% (5/231); p < 0.001]. Patients with sterile intra-amniotic inflammation had a significantly higher rate of sPTD <34 weeks of gestation [70.8% (17/24) versus 31.6% (55/174); p < 0.001] and a significantly shorter amniocentesis-to-delivery interval than patients without intra-amniotic inflammation [median 35, (IQR: 10-70) versus median 71, (IQR: 47-98) days, (p < 0.0001)].

CONCLUSION

Sterile intra-amniotic inflammation is more common than microbial-associated intra-amniotic inflammation in asymptomatic women with a sonographic short cervix, and is associated with increased risk of sPTD (<34 weeks). Further investigation is required to determine the causes of sterile intra-amniotic inflammation and the mechanisms whereby this condition is associated with a short cervix and sPTD.

Prediction of preterm birth in twin gestations using biophysical and biochemical tests

The objective of this study was to determine the performance of biophysical and biochemical tests for the prediction of preterm birth in both asymptomatic and symptomatic women with twin gestations. We identified a total of 19 tests proposed to predict preterm birth, mainly in asymptomatic women. In these women, a single measurement of cervical length with transvaginal ultrasound before 25 weeks of gestation appears to be a good test to predict preterm birth. Its clinical potential is enhanced by the evidence that vaginal progesterone administration in asymptomatic women with twin gestations and a short cervix reduces neonatal morbidity and mortality associated with spontaneous preterm delivery. Other tests proposed for the early identification of asymptomatic women at increased risk of preterm birth showed minimal to moderate predictive accuracy. None of the tests evaluated in this review meet the criteria to be considered clinically useful to predict preterm birth among patients with an episode of preterm labor. However, a negative cervicovaginal fetal fibronectin test could be useful in identifying women who are not at risk for delivering within the next week, which could avoid unnecessary hospitalization and treatment. This review underscores the need to develop accurate tests for predicting preterm birth in twin gestations. Moreover, the use of interventions in these patients based on test results should be associated with the improvement of perinatal outcomes.

Chemotactic activity of gestational tissues through late pregnancy, term labor, and RU486-induced preterm labor in Guinea pigs

PROBLEM

Is increased leukocyte chemotactic activity (CA) from gestational tissues necessary for term or preterm labor in guinea pigs?

METHOD OF STUDY

Tissue extracts were prepared from pregnant guinea pig decidua-myometrium, cervix, fetal membranes (amniochorion), and placenta during early third trimester (n = 8), term not in labor (TNL, n = 5), and term spontaneous labor (TL, n = 6), RU486-induced preterm labor (PTL, n = 6), or controls (cPTL, n = 5). Leukocyte CA was assessed using a modified Boyden chamber assay. Extract chemokine and maternal progesterone concentrations were quantified by enzyme immunoassay.

RESULTS

Only the extracts from amniochorion demonstrated increased CA through late gestation and labor. In contrast, CA was decreased in extracts from amniochorion and cervix from animals after RU486-induced PTL. Maternal progesterone concentrations remained high in all groups.

CONCLUSION

Leukocyte CA of intrauterine tissues is increased in term spontaneous labor. However, RU486-induced preterm labor occurs in the absence of increased CA.

Cnr2 deficiency confers resistance to inflammation-induced preterm birth in mice

Infection-induced inflammation, frequently associated with increased production of proinflammatory cytokines, is considered a significant contributor to preterm birth. A G protein-coupled cannabinoid receptor 2 (CB2), encoded by Cnr2, is expressed in various immune cells and was shown to modulate immune responses. We show here that Cnr2, but not Cnr1, deficient mice are resistant to lipopolysaccharide (LPS)-driven preterm birth and suppression of serum progesterone levels. After LPS challenge, Cnr2(-/-) mice exhibited increased serum levels of IL-10 with decreased IL-6 levels. These changes were associated with reduced LPS-induced Ptgs2 expression at the maternal-conceptus interface on day 16 of pregnancy. LPS stimulation of Cnr2(-/-) dendritic cells in vitro resulted in increased IL-10 with reduced IL-6 production and correlated with increased cAMP accumulation. Collectively, our results suggest that increased IL-10 production occurring via augmented cAMP accumulation represents a potential mechanism for the resistance of Cnr2(-/-) mice to LPS-induced preterm birth. These results may have clinical relevance, because currently, there are limited options to prevent preterm birth.

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

PROBLEM

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

METHOD OF STUDY

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

RESULTS

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

CONCLUSION

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

Increased neopterin level and chitotriosidase activity in pregnant women with threatened preterm labor

OBJECTIVES

To determine whether the cellular inflammatory markers of activated macrophages, neopterin (NEO), chitotriosidase activity and the acute-phase inflammatory marker C-reactive protein (CRP) are elevated in pregnancy with threatened preterm labor (TPL).

METHODS

Thirty-two pregnant women with TPL and 32 women with uncomplicated pregnancy (UP) were included this study. The primary aim was to compare the NEO, chitotriosidase activity and CRP levels between women with TPL and women with UP.

RESULTS

NEO levels were all significantly elevated in patients with TPL compared to UP (median 25-75%; 9.61 [8.47-12.29] versus 4.46 [3.59-6.92], respectively; p < 0.001). Chitotriosidase activity was significantly elevated in pregnant women with TPL compared to UP (median 25-75%; 59.00 [38.00-87.25] versus 43.50 [23.25-65.25], respectively; p = 0.036). However, CRP levels were not different in women with TPL compared to UP (p = 0.573). Furthermore, a significant moderate negative correlation was found between delivery week and NEO level (r = -0.557, p = 0.001). However, a significant correlation was not seen between delivery week and chitotriosidase activity (r = -0.042, p = 0.741).

CONCLUSIONS

Inflammatory markers such as NEO and chitotriosidase activity, which are markers of macrophages, are more elevated in pregnant women with TPL than in women with UP. These data suggest that there are striking increases in inflammation and cellular immune activation in TPL.

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.

Strain-dependent effects of prenatal maternal immune activation on anxiety- and depression-like behaviors in offspring

There is converging evidence that prenatal maternal infection can increase the risk of occurrence of neuropsychiatric disorders like schizophrenia, autism, anxiety and depression in later life. Experimental studies have shown conflicting effects of prenatal maternal immune activation on anxiety-like behavior and hypothalamic-pituitary-adrenal (HPA) axis development in offspring. We investigated the effects of maternal immune activation during pregnancy on anxiety- and depression-like behaviors in pregnant mice and their offspring to determine whether these effects are dependent on strain. NMRI and C57BL/6 pregnant mice were treated with either saline or lipopolysaccharide on gestational day 17 and then interleukin (IL)-6 and corticosterone (COR) levels; anxiety or depression in the pregnant mice and their offspring were evaluated. The results indicate that maternal inflammation increased the levels of COR and anxiety-like behavior in NMRI pregnant mice, but not in C57BL/6 dams. Our data also demonstrate that maternal inflammation elevated the levels of anxiety-and depression-like behaviors in NMRI offspring on the elevated plus-maze, elevated zero-maze, tail suspension test and forced swimming test respectively, but not in the open field and light-dark box. In addition, we did not find any significant change in anxiety- and depression-like behaviors of adult C57BL/6 offspring. Our findings suggest that prenatal maternal immune activation can alter the HPA axis activity, anxiety- and depression-like behaviors in a strain- and task-dependent manner in offspring and further comprehensive studies are needed to prove the causal relationship between the findings found here and to validate their relevance to neuropsychiatric disorders in humans.

Soluble ST2, a modulator of the inflammatory response, in preterm and term labor

OBJECTIVE

Intra-amniotic infection/inflammation (IAI) is causally linked with spontaneous preterm labor and delivery. The ST2L receptor and its soluble form (sST2) are capable of binding to interleukin (IL)-33, a member of the IL-1 superfamily. Members of this cytokine family have been implicated in the onset of spontaneous preterm labor in the context of infection. Soluble ST2 has anti-inflammatory properties, and plasma concentrations are elevated in systemic inflammation, such as sepsis, acute pyelonephritis in pregnancy and the fetal inflammatory response syndrome. The aims of this study were to examine: (1) whether amniotic fluid concentrations of sST2 change with IAI, preterm, and term parturition; and (2) if mRNA expression of ST2 in the chorioamniotic membranes changes with acute histologic chorioamnionitis in women who deliver preterm.

METHOD

A cross-sectional study was conducted to determine amniotic fluid concentrations of sST2 in: (1) women with preterm labor (PTL) who delivered at term (n=49); (2) women with PTL who delivered preterm without IAI (n=21); (3) women with PTL who delivered preterm with IAI (n=31); (4) term pregnancies not in labor (n=13); and (5) term pregnancies in labor (n=43). The amniotic fluid concentration of sST2 was determined by ELISA. The mRNA expression of ST2 in the chorioamniotic membranes of women who delivered preterm with (n=24), and without acute histologic chorioamnionitis (n=19) was determined by qRT-PCR.

RESULTS

(1) Patients with PTL who delivered preterm with IAI had a lower median amniotic fluid concentration of sST2 compared to those with PTL who delivered preterm without IAI [median 410 ng/mL, inter-quartile range (IQR) 152-699 ng/mL versus median 825 ng/mL, IQR 493-1216 ng/mL; p=0.0003] and those with PTL who delivered at term [median 410 ng/mL, IQR 152-699 ng/mL versus median 673 ng/mL, IQR 468-1045 ng/mL; p=0.0003]; (2) no significant differences in the median amniotic fluid concentration of sST2 were observed between patients with PTL who delivered at term and those who delivered preterm without IAI (p=0.4), and between women at term in labor and those at term not in labor (p=0.9); (3) the mean mRNA expression of ST2 was 4-fold lower in women who delivered preterm with acute histologic chorioamnionitis than in those without this lesion (p=0.008).

CONCLUSIONS

The median sST2 amniotic fluid concentration and mRNA expression of ST2 by chorioamniotic membranes is lower in PTL associated with IAI and acute histologic chorioamnionitis than in PTL without these conditions. Changes in the median amniotic fluid sST2 concentration are not observed in preterm and term parturition without IAI. Thus, amniotic fluid sST2 in the presence of IAI behaves differently when compared to sST2 in the plasma of individuals affected by fetal inflammatory response syndrome, acute pyelonephritis in pregnancy, and adult sepsis. Decreased concentrations of sST2 in IAI are likely to promote a pro-inflammatory response, which is important for parturition in the context of infection.