Histological chorioamnionitis shapes the neonatal transcriptomic immune response

The role of the placenta-brain axis in psychoneuroimmune programming

Gestational exposures have enduring impacts on brain and neuroimmune development and function. Perturbations of pregnancy leading to placental structure/function deficits, cell stress, immune activation, and endocrine changes (metabolic, growth factors, etc.) all increase neuropsychiatric risk in offspring. The existing literature links obstetric diseases with placental involvement to offspring neuroimmune outcomes and neurodevelopmental risk. Psychoneuroimmune outcomes in offspring brain include changes to microglia, cytokine/chemokine production, cell stress, and long-term immunoreactivity. These outcomes are altered by structural, anti-angiogenic/hypoxic, inflammatory, and metabolic diseases of the placenta. This fetal programming occurs via direct placental passage or production of factors which can act directly on fetal brain substrates, or indirectly via action of circulating factors on intermediates in the placenta. Placental neuroendocrine, vascular/angiogenic, immune, and extracellular vesicular mechanisms are detailed. These mechanisms interact within various placental and pregnancy conditions. An increased understanding of the placental origins of psychoneuroimmunology will yield dividends for human health. Identifying maternal and placental biomarkers for fetal neuroimmune health may also revolutionize early diagnosis and precision psychiatry, empowering patients to make the best healthcare decisions for their families. Targeting placental mechanisms may be a valuable approach for the prevention and mitigation of intergenerational, lifelong neuropathology.

The Association between Term Chorioamnionitis during Labor and Long-Term Infectious Morbidity of the Offspring

Background: Chorioamnionitis during labor exposes the fetus to an intrauterine state that may alter the future immune response and may expose the offspring to future susceptibility to infectious disease. We evaluated the long-term pediatric infectious morbidity of children born at term to mothers who have chorioamnionitis during labor. Methods: This was a population-based cohort analysis including only term singleton deliveries at a regional tertiary hospital between the years 1991 and 2021. Offspring to mothers with and without a diagnosis of chorioamnionitis during labor were compared. Offspring hospitalizations up to the age of 18 years involving infectious morbidity were evaluated using the Kaplan-Meier survival curve and a Cox regression model to control possible confounders. Results: A total of 331,598 deliveries were included, 988 (0.3%) of which were of mothers diagnosed with chorioamnionitis during labor. All infectious morbidity rates included in the analysis were comparable between groups. The Kaplan-Meier survival curves were similar for both groups (log-rank = 0.881) and the multivariable analysis ascertained that chorioamnionitis during labor was not a risk factor for offspring's long-term infectious morbidity (HR 0.929, 95%CI 0.818-1.054, p = 0.254). Conclusions: In our cohort, term chorioamnionitis during labor was not associated with a higher risk of pediatric hospitalization due to infections. The infectious/inflammatory state during labor did not expose nor increase the susceptibility of the term offspring to future infectious morbidity.

Establishment of a prediction model for histological chorioamnionitis and its association with outcomes of premature infants

Aim

This study aims to construct a prediction model for histological chorioamnionitis (HCA) and analyze the associations between the predicted risk of HCA and adverse outcomes in preterm infants.

Methods

In total, 673 subjects were included in this cohort study and divided into HCA group (n = 195) and non-HCA group (n = 478). A stepwise method was used to screen the predictors for HCA, binary logistic regression was used to construct the prediction model, and the associations between the predicted risk of HCA and adverse outcomes were analyzed.

Results

HCA occurred in 195 patients, accounting for 29.0%. The sensitivity of the prediction model was 0.821 [95% confidence interval (CI): 0.767-0.874)], the specificity was 0.684 (95% CI: 0.642-0.726), the positive predictive value was 0.514 (0.459-0.570), the negative predictive value was 0.903 (95% CI: 0.873-0.934), the area under the curve was 0.821 (95% CI: 0.786-0.855), and the accuracy was 0.724 (95% CI: 0.690-0.757). The predicted risk of HCA was associated with a higher risk of bronchopulmonary dysplasia (BPD) [odds ratio (OR) = 3.48, 95% CI: 1.10-10.95)], sepsis (OR = 6.66, 95% CI: 2.17-20.43), and neonatal infections (OR = 9.85, 95% CI: 3.59-26.98), but not necrotizing enterocolitis (OR = 0.67, 95% CI: 0.24-1.88), retinopathy of prematurity (OR = 1.59, 95% CI: 0.37-6.85), and brain damage (OR = 1.77, 95% CI: 0.82-3.83). After adjusting for confounders including gestational week at birth and birth weight, the risk of neonatal infections (OR = 5.03, 95% CI: 2.69-9.41) was increased in preterm infants' exposure to HCA.

Conclusion

The model showed good predictive performance for identifying pregnant women with a higher risk of HCA. In addition, HCA was associated with the risk of BPD, sepsis, and infections in neonates.

Inflammatory Biomarker Profiles in Very Preterm Infants within the Context of Preeclampsia, Chorioamnionitis, and Clinically Diagnosed Postnatal Infection

Preterm delivery can be precipitated by preeclampsia or infection, and preterm infants are at heightened risk of postnatal infection. Little is known about the ontogeny of inflammatory biomarkers in extremely preterm infants. We hypothesized that suspected prenatal infection (clinical chorioamnionitis or spontaneous preterm labor) and clinically diagnosed postnatal infection would be associated with unique biomarker signatures, and those patterns would be influenced by the degree of prematurity. Venous blood was collected daily for the first week and weekly for up to 14 additional weeks from 142 neonates born at 22-32 weeks gestation. A custom array was utilized to measure monocyte chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6). C-reactive protein (CRP) levels were obtained from the electronic medical record. Independent of gestational age, MCP-1 was significantly increased (p < 0.001) in association with maternal preeclampsia, but MCP-1 was decreased (p < 0.01), and CRP was increased (p < 0.01) in the presence of chorioamnionitis with funisitis. IL-6 and CRP were both increased in infants diagnosed with postnatal infection, with peak levels observed on days 2 and 3, respectively. In conclusion, suspected prenatal and postnatal infections and non-infectious complications of pregnancy are associated with unique biomarker profiles, independent of gestational age, including over a 2-fold increase in MCP-1 among newborns of mothers with preeclampsia. Further, in those clinically diagnosed with a postnatal infection in the absence of antenatal infection concerns, IL-6 increases before CRP, emphasizing a potential role for expanded biomarker screening if antibiotics are initially avoided in infants delivered for maternal indications.

In utero priming of fetal immune activation: Myths and mechanisms

Mechanisms of fetal immune system development in utero remain incompletely elucidated. Protective immunity, the arm of reproductive immunology concerned with the progressive education of the fetal immune system as pregnancy advances, allows for programming of the immune system and immune maturation in utero and provides a responsive system to respond to rapid microbial and other antigenic exposure ex utero. Challenges in studying fetal tissues, immune system development, and the contributions of various endogenous and exogenous factors to this process are difficult to study as a progressive sampling of fetal biological samples is impractical during pregnancy, and animal models are limited. This review provides a summary of mechanisms of protective immunity and how it has been shaped, from transplacental transfer of immunoglobulins, cytokines, metabolites, as well as antigenic microchimeric cells to perhaps more controversial notions of materno-fetal transfer of bacteria that subsequently organize into microbiomes within the fetal tissues. This review will also provide a quick overview of future direction in the area of research on fetal immune system development and discusses methods to visualize fetal immune populations and determine fetal immune functions, as well as a quick look into appropriate models for studying fetal immunity.

Omics approaches: interactions at the maternal-fetal interface and origins of child health and disease

Immunoperinatology is an emerging field. Transdisciplinary efforts by physicians, physician-scientists, basic science researchers, and computational biologists have made substantial advancements by identifying unique immunologic signatures of specific diseases, discovering innovative preventative or treatment strategies, and establishing foundations for individualized neonatal intensive care of the most vulnerable neonates. In this review, we summarize the immunobiology and immunopathology of pregnancy, highlight omics approaches to study the maternal-fetal interface, and their contributions to pregnancy health. We examined the importance of transdisciplinary, multiomic (such as genomics, transcriptomics, proteomics, metabolomics, and immunomics) and machine-learning strategies in unraveling the mechanisms of adverse pregnancy, neonatal, and childhood outcomes and how they can guide the development of novel therapies to improve maternal and neonatal health. IMPACT: Discuss immunoperinatology research from the lens of omics and machine-learning approaches. Identify opportunities for omics-based approaches to delineate infection/inflammation-associated maternal, neonatal, and later life adverse outcomes (e.g., histologic chorioamnionitis [HCA]).

Chorioamnionitis and neonatal outcomes

Chorioamnionitis or intrauterine inflammation is a frequent cause of preterm birth. Chorioamnionitis can affect almost every organ of the developing fetus. Multiple microbes have been implicated to cause chorioamnionitis, but "sterile" inflammation appears to be more common. Eradication of microorganisms has not been shown to prevent the morbidity and mortality associated with chorioamnionitis as inflammatory mediators account for continued fetal and maternal injury. Mounting evidence now supports the concept that the ensuing neonatal immune dysfunction reflects the effects of inflammation on immune programming during critical developmental windows, leading to chronic inflammatory disorders as well as vulnerability to infection after birth. A better understanding of microbiome alterations and inflammatory dysregulation may help develop better treatment strategies for infants born to mothers with chorioamnionitis.

COVID-19 Infection During Pregnancy Induces Differential Gene Expression in Human Cord Blood Cells From Term Neonates

BACKGROUND

The COVID-19 pandemic continues worldwide with fluctuating case numbers in the United States. This pandemic has affected every segment of the population with more recent hospitalizations in the pediatric population. Vertical transmission of COVID-19 is uncommon, but reports show that there are thrombotic, vascular, and inflammatory changes in the placenta to which neonates are prenatally exposed. Individuals exposed in utero to influenza during the 1918 pandemic had increased risk for heart disease, kidney disease, diabetes, stomach disease and hypertension. Early exposure of COVID-19 during fetal life may lead to altered gene expression with potential long-term consequences.

OBJECTIVE

To determine if gene expression is altered in cord blood cells from term neonates who were exposed to COVID-19 during pregnancy and to identify potential gene pathways impacted by maternal COVID-19.

METHODS

Cord blood was collected from 16 term neonates (8 exposed to COVID-19 during pregnancy and 8 controls without exposure to COVID-19). Genome-wide gene expression screening was performed using Human Clariom S gene chips on total RNA extracted from cord blood cells.

RESULTS

We identified 510 differentially expressed genes (374 genes up-regulated, 136 genes down-regulated, fold change ≥1.5, p-value ≤ 0.05) in cord blood cells associated with exposure to COVID-19 during pregnancy. Ingenuity Pathway Analysis identified important canonical pathways associated with diseases such as cardiovascular disease, hematological disease, embryonic cancer and cellular development. Tox functions related to cardiotoxicity, hepatotoxicity and nephrotoxicity were also altered after exposure to COVID-19 during pregnancy.

CONCLUSIONS

Exposure to COVID-19 during pregnancy induces differential gene expression in cord blood cells. The differentially expressed genes may potentially contribute to cardiac, hepatic, renal and immunological disorders in offspring exposed to COVID-19 during pregnancy. These findings lead to a further understanding of the effects of COVID-19 exposure at an early stage of life and its potential long-term consequences as well as therapeutic targets.

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

Background

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

Methods

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

Results

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

Conclusions

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

Postnatal inflammation in ApoE-/- mice is associated with immune training and atherosclerosis

BACKGROUND AND AIMS

Preterm birth is associated with increased risk of cardiovascular disease (CVD). This may reflect a legacy of inflammatory exposures such as chorioamnionitis which complicate pregnancies delivering preterm, or recurrent early-life infections, which are common in preterm infants. We previously reported that experimental chorioamnionitis followed by postnatal inflammation has additive and deleterious effects on atherosclerosis in ApoE-/- mice. Here, we aimed to investigate whether innate immune training is a contributory inflammatory mechanism in this murine model of atherosclerosis.

METHODS

Bone marrow-derived macrophages and peritoneal macrophages were isolated from 13-week-old ApoE-/- mice, previously exposed to prenatal intra-amniotic (experimental choriomanionitis) and/or repeated postnatal (peritoneal) lipopolysaccharide (LPS). Innate immune responses were assessed by cytokine responses following ex vivo stimulation with toll-like receptor (TLR) agonists (LPS, Pam3Cys) and RPMI for 24-h. Bone marrow progenitor populations were studied using flow cytometric analysis.

RESULTS

Following postnatal LPS exposure, bone marrow-derived macrophages and peritoneal macrophages produced more pro-inflammatory cytokines following TLR stimulation than those from saline-treated controls, characteristic of a trained phenotype. Cytokine production ex vivo correlated with atherosclerosis severity in vivo. Prenatal LPS did not affect cytokine production capacity. Combined prenatal and postnatal LPS exposure was associated with a reduction in populations of myeloid progenitor cells in the bone marrow.

CONCLUSIONS

Postnatal inflammation results in a trained phenotype in atherosclerosis-prone mice that is not enhanced by prenatal inflammation. If analogous mechanisms occur in humans, then there may be novel early life opportunities to reduce CVD risk in infants with early life infections.

COVID-19 in pregnancy: Placental and neonatal involvement

Since December 2019, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has caused over 12 million infections and more than 550 000 deaths.¹ Morbidity and mortality appear partly due to host inflammatory response.² Despite rapid, global research, the effect of SARS‐CoV‐2 on the developing fetus remains unclear. Case reports indicate that vertical transmission is uncommon; however, there is evidence that placental and fetal infection can occur.^3‐7 Placentas from infected patients show inflammatory, thrombotic, and vascular changes that have been found in other inflammatory conditions.^8,9 This suggests that the inflammatory nature of SARS‐CoV‐2 infection during pregnancy could cause adverse obstetric and neonatal events. Exposure to intrauterine inflammation and placental changes could also potentially result in long‐term, multisystemic defects in exposed infants. This review will summarize the known literature on the placenta in SARS‐CoV‐2 infection, evidence of vertical transmission, and possible outcomes of prenatal exposure to the virus.

Mechanisms of brain injury in newborn infants associated with the fetal inflammatory response syndrome

The fetal inflammatory response syndrome (FIRS) is characterized by umbilical cord inflammation and elevated fetal pro-inflammatory cytokines. Surviving neonates, especially very preterm infants, have increased rates of neonatal morbidity including neurodevelopmental impairment. The mechanism of brain injury in FIRS is complex and may involve "multiple hits." Exposure to in utero inflammation initiates a cascade of the fetal immune response, where pro-inflammatory cytokines can cause direct injury to oligodendrocytes and neurons. Activation of microglia results in further injury to vulnerable pre-myelinating oligodendrocytes and influences the integrity of the fetal and newborn's blood-brain barrier, resulting in further exposure of the brain to developmental insults. Newborns exposed to FIRS are frequently exposed to additional perinatal and postnatal insults that can result in further brain injury. Future directions should include evaluations for new therapeutic interventions aimed at reducing brain injury by dampening FIRS, inhibition of microglial activation, and regeneration of immature oligodendrocytes.

Neurologic outcome after fetal inflammatory response syndrome: Trimester-specific considerations

Clinical signs and neuroimaging patterns associated with the fetal inflammatory response syndrome (FIRS) worsen or mimic the clinical repertoire after intrapartum hypoxic-ischemic encephalopathy (HIE) during labor and/or parturition. Diagnostic considerations expressed as neonatal encephalopathy (NE) must consider chronic as well as acute factors associated with FIRS. Trimester-specific factors adversely alter the interactions of the maternal/placental/fetal (MPF) triad and influence the postnatal phenotype of FIRS. Anticipatory guidance for families by clinicians caring for survivors with FIRS, as well as researchers, must consider acute and chronic effects that influence neurologic outcome. Novel neurotherapeutic interventions must include prenatal preventive as well as peripartum/postnatal rescue and repair strategies to effectively reduce the presence and severity of sequelae from FIRS.

A perfect storm: fetal inflammation and the developing immune system

Histologic chorioamnionitis is an inflammatory disorder of the placenta that commonly precedes preterm delivery. Preterm birth related to chorioamnionitis and fetal inflammation has been associated with a risk for serious inflammatory complications in infancy. In addition, preterm infants exposed to chorioamnionitis may be more susceptible to infection in the neonatal intensive care unit and possibly later in life. A significant body of work has established an association between chorioamnionitis and inflammatory processes. However, the potential consequences of this inflammation on postnatal immunity are less understood. In this review, we will discuss current knowledge regarding the effects of fetal exposure to inflammation on postnatal immune responses.

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

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

Prenatal inflammation suppresses blood Th1 polarization and gene clusters related to cellular energy metabolism in preterm newborns

Chorioamnionitis (CA, fetal membrane inflammation) predisposes to preterm birth and is associated with increased neonatal infection risk, but the separate effects of prematurity, CA, and postnatal adaptations on this risk are unclear. Using pigs as models for infants, we examined the systemic immune-metabolic status in cesarean-delivered preterm pigs, with and without CA induced by intra-amniotic (IA) LPS exposure. At birth, cord blood of preterm pigs showed neutropenia and low expressions of innate and adaptive immune genes, relative to term pigs. IA LPS induced CA and fetal systemic innate immune activation via complement and neutrophil-related pathways. These were mainly modulated via cellular regulations rather than granulopoiesis, as validated by the in vitro LPS stimulation of cord blood. After birth, IA LPS-exposed preterm pigs did not follow normal immune-metabolic ontogenies found in fetuses or newborns without prenatal insults, but showed consistently high levels of Treg, impaired Th1 polarization, and reduced expressions of multiple genes related to cellular oxidative phosphorylation and ribosomal activities. In conclusion, our results provide cellular and molecular evidence for CA-induced distinct neonatal immune-metabolic status with increased disease tolerance strategy, suggesting mechanisms for the clinical observation of elevated sepsis risks in immune-compromised preterm infants born with CA.

Fetal exposure to maternal inflammation interrupts murine intestinal development and increases susceptibility to neonatal intestinal injury

Fetal exposure to chorioamnionitis can impact the outcomes of the developing fetus both at the time of birth and in the subsequent neonatal period. Infants exposed to chorioamnionitis have a higher incidence of gastrointestinal (GI) pathology, including necrotizing enterocolitis (NEC); however, the mechanism remains undefined. To simulate the fetal exposure to maternal inflammation (FEMI) induced by chorioamnionitis, pregnant mice (C57BL/6J, IL-6 ^-/-, RAG ^-/- or TNFR1 ^-/-) were injected intraperitoneally on embryonic day (E)15.5 with lipopolysaccharide (LPS; 100 µg/kg body weight). Pups were delivered at term, and reared to postnatal day (P)0, P7, P14, P28 or P56. Serum and intestinal tissue samples were collected to quantify growth, inflammatory markers, histological intestinal injury, and goblet and Paneth cells. To determine whether FEMI increased subsequent susceptibility to intestinal injury, a secondary dose of LPS (100 µg/kg body weight) was given on P5, prior to tissue harvesting on P7. FEMI had no effect on growth of the offspring or their small intestine. FEMI significantly decreased both goblet and Paneth cell numbers while simultaneously increasing serum levels of IL-1β, IL-10, KC/GRO (CXCL1 and CXCL2), TNF and IL-6. These alterations were IL-6 dependent and, importantly, increased susceptibility to LPS-induced intestinal injury later in life. Our data show that FEMI impairs normal intestinal development by decreasing components of innate immunity and simultaneously increasing markers of inflammation. These changes increase susceptibility to intestinal injury later in life and provide novel mechanistic data to potentially explain why preterm infants exposed to chorioamnionitis prior to birth have a higher incidence of NEC and other GI disorders.

Histological Chorioamnionitis Induces Differential Gene Expression in Human Cord Blood Mononuclear Leukocytes from Term Neonates

Histological chorioamnionitis (HCA) is an infection of fetal membranes and complicates 5.2% to 28.5% of all live births. HCA is associated with increased mortality and morbidity in both premature and term neonates. Exposure to HCA may have long-term consequences, including an increased risk for allergic disorders and asthma later in childhood, the mechanism(s) of which are still not yet well understood. The objective of this study was to determine the mRNA transcriptome of cord blood mononuclear leukocytes from term neonates to identify key genes and pathways involved in HCA. We found 366 differentially expressed probe IDs with exposure to HCA (198 upregulated, 168 downregulated). These transcriptomes included novel genes and pathways associated with exposure to HCA. The differential gene expression included key genes regulating inflammatory, immune, respiratory and neurological pathways, which may contribute to disorders in those pathways in neonates exposed to HCA. Our data may lead to understanding of the role of key genes and pathways identified on the long-term sequelae related to exposure to HCA, as well as to identifying potential markers and therapies to prevent HCA-associated complications.

CXCR2 Blockade Mitigates Neural Cell Injury Following Preclinical Chorioamnionitis

Minimizing central nervous system (CNS) injury from preterm birth depends upon identification of the critical pathways that underlie essential neurodevelopmental and CNS pathophysiology. While chorioamnionitis (CHORIO), is a leading cause of preterm birth, the precise mechanism linking prenatal brain injury and long-term CNS injury is unknown. The chemokine (C-X-C motif) ligand 1 (CXCL1) and its cognate receptor, CXCR2, are implicated in a variety of uterine and neuropathologies, however, their role in CNS injury associated with preterm birth is poorly defined. To evaluate the putative efficacy of CXCR2 blockade in neural repair secondary to CHORIO, we tested the hypothesis that transient postnatal CXCR2 antagonism would reduce neutrophil activation and mitigate cerebral microstructural injury in rats. To this end, a laparotomy was performed on embryonic day 18 (E18) in Sprague Dawley rats, with uterine arteries transiently occluded for 60 min, and lipopolysaccharide (LPS, 4 μg/sac) injected into each amniotic sac. SB225002, a CXCR2 antagonist (3 mg/kg), was administered intraperitoneally from postnatal day 1 (P1)-P5. Brains were collected on P7 and P21 and analyzed with western blot, immunohistochemistry and ex vivo diffusion tensor imaging (DTI). Results demonstrate that transient CXCR2 blockade reduced cerebral neutrophil activation (myeloperoxidase expression/MPO) and mitigated connexin43 expression, indicative of reduced neuroinflammation at P7 (p < 0.05 for all). CXCR2 blockade also reduced alpha II-spectrin calpain-mediated cleavage, improved pNF/NF ratio, and minimized Iba1 and GFAP expression consistent with improved neuronal and axonal health and reduced gliosis at P21. Importantly, DTI revealed diffuse white matter injury and decreased microstructural integrity following CHORIO as indicated by lower fractional anisotropy (FA) and elevated radial diffusivity (RD) in major white matter tracts (p < 0.05). Early postnatal CXCR2 blockade also reduced microstructural abnormalities in white matter and hippocampus at P21 (p < 0.05). Together, these data indicate that transient postnatal blockade of CXCR2 ameliorates perinatal abnormalities in inflammatory signaling, and facilitates neural repair following CHORIO. Further characterization of neuroinflammatory signaling, specifically via CXCL1/CXCR2 through the placental-fetal-brain axis, may clarify stratification of brain injury following preterm birth, and improve use of targeted interventions in this highly vulnerable patient population.

Chorioamnionitis exposure remodels the unique histone modification landscape of neonatal monocytes and alters the expression of immune pathway genes

Chorioamnionitis is an intrauterine infection involving inflammation of the chorion, amnion, and placenta. It leads to a fetal systemic inflammatory response that can alter the transcription of neonatal immune genes. We have previously shown that neonatal monocytes gain the activating histone tail modification H3K4me3 at promoter sites of immunologically important genes as development progresses from preterm neonate to adult. In this study, we applied ChIP-seq and RNA-seq to evaluate the impact of chorioamnionitis on the neonatal monocyte H3K4me3 histone modification landscape over the course of fetal and neonatal immune system development. Chorioamnionitis exposure in neonatal monocytes resulted in a net increase in total monocyte H3K4me3, primarily in introns and intergenic regions. Immune gene expression was decreased in chorioamnionitis-exposed monocytes, with the majority of enriched transcripts falling into pathways that are not linked to the immune system. Over half of all neonatal monocyte H3K4me3 peaks, independent of their location, were associated with active gene transcription. Overall, chorioamnionitis exposure resulted in the global remodeling of the neonatal monocyte H3K4me3 landscape and changes in the expression of known immune genes. These changes resulted in a less robust inflammatory response upon exposure to a secondary challenge, which may explain why chorioamnionitis-exposed neonates have an increased risk of sepsis. DATABASE: ChIP-seq data for U30/O30/Term: GEO GSE81957 ChIP-seq data for U30C/O30C/TermC: GEO GSE111873 RNA-seq data for U/L/CU/CL: GEO GSE111927.

Validation of the Sepsis MetaScore for Diagnosis of Neonatal Sepsis

WHAT’S KNOWN ON THIS SUBJECT

Neonates are at increased risk for developing sepsis, but this population often exhibits ambiguous clinical signs that complicate the diagnosis of infection. No biomarker has yet shown enough diagnostic accuracy to rule out sepsis at the time of clinical suspicion.

WHAT THIS STUDY ADDS

We show that a gene-expression-based signature is an accurate objective measure of the risk of sepsis in a neonate or preterm infant, and it substantially improves diagnostic accuracy over that of commonly used laboratory-based testing. Implementation might decrease inappropriate antibiotic use.

BACKGROUND

Neonatal sepsis can have devastating consequences, but accurate diagnosis is difficult. As a result, up to 200 neonates with suspected sepsis are treated with empiric antibiotics for every 1 case of microbiologically confirmed sepsis. These unnecessary antibiotics enhance bacterial antibiotic resistance, increase economic costs, and alter gut microbiota composition. We recently reported an 11-gene diagnostic test for sepsis (Sepsis MetaScore) based on host whole-blood gene expression in children and adults, but this test has not been evaluated in neonates.

METHODS

We identified existing gene expression microarray-based cohorts of neonates with sepsis. We then tested the accuracy of the Sepsis MetaScore both alone and in combination with standard diagnostic laboratory tests in diagnosing sepsis.

RESULTS

We found 3 cohorts with a total of 213 samples from control neonates and neonates with sepsis. The Sepsis MetaScore had an area under the receiver operating characteristic curve of 0.92-0.93 in all 3 cohorts. We also found that, as a diagnostic test for sepsis, it outperformed standard laboratory measurements alone and, when used in combination with another test(s), resulted in a significant net reclassification index (0.3-0.69) in 5 of 6 comparisons. The mean point estimates for sensitivity and specificity were 95% and 60%, respectively, which, if confirmed prospectively and applied in a high-risk cohort, could reduce inappropriate antibiotic usage substantially.

CONCLUSIONS

The Sepsis MetaScore had excellent diagnostic accuracy across 3 separate cohorts of neonates from 3 different countries. Further prospective targeted study will be needed before clinical application.

Serum concentrations of endothelial cell adhesion molecules and their shedding enzymes and early onset sepsis in newborns in Suriname

BACKGROUND

Early onset sepsis (EOS) is defined as onset of sepsis within 72 hours after birth. Leucocyte-endothelial interactions play a pivotal part in EOS pathophysiology. Endothelial cell adhesion molecules (CAMs) orchestrate these interactions and their soluble isoforms (sCAMs) are released into the vasculature by enzymes called sheddases.

PURPOSE

This study was undertaken to explore further the pathophysiology of EOS and to investigate the potential of sCAM and their sheddases as potential biomarkers for EOS.

METHODS

Stored serum aliquots were used from 71 Surinamese newborns suspected of EOS and 20 healthy newborns from an earlier study. Serum had been collected within 72 hours after birth and six (8.6%) newborns had a positive blood culture with gram-negative pathogens. Concentrations of sCAMs sP-selectin, sE-selectin, soluble vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and platelet and endothelial cell adhesion molecule-1, sheddases matrix metalloproteinase-9 (MMP-9) and neutrophil elastase (NE) and sheddase antagonist tissue-inhibitor of metalloproteinases-1 (TIMP-1) were measured simultaneously with Luminex and ELISA.

RESULTS

MMP-9 and TIMP-1 levels were measured in serum of n=91 newborns and sCAMs and NE levels in serum of n=80 newborns, respectively. We found no differences in median concentrations of sCAMs, MMP-9 and TIMP-1 or NE between blood culture positive EOS, blood culture negative EOS and control groups at start of antibiotic treatment.

CONCLUSIONS

Our data indicate that serum concentrations of sCAMs and their sheddases have no clinical utility as biomarkers for EOS.

TRIAL REGISTRATION NUMBER

NCT02486783. Results.

In Utero Exposure to Histological Chorioamnionitis Primes the Exometabolomic Profiles of Preterm CD4+ T Lymphocytes

Histological chorioamnionitis (HCA) is an intrauterine inflammatory condition that increases the risk for preterm birth, death, and disability because of persistent systemic and localized inflammation. The immunological mechanisms sustaining this response in the preterm newborn remain unclear. We sought to determine the consequences of HCA exposure on the fetal CD4+ T lymphocyte exometabolome. We cultured naive CD4+ T lymphocytes from HCA-positive and -negative preterm infants matched for gestational age, sex, race, prenatal steroid exposure, and delivery mode. We collected conditioned media samples before and after a 6-h in vitro activation of naive CD4+ T lymphocytes with soluble staphylococcal enterotoxin B and anti-CD28. We analyzed samples by ultraperformance liquid chromatography ion mobility-mass spectrometry. We determined the impact of HCA on the CD4+ T lymphocyte exometabolome and identified potential biomarker metabolites by multivariate statistical analyses. We discovered that: 1) CD4+ T lymphocytes exposed to HCA exhibit divergent exometabolomic profiles in both naive and activated states; 2) ∼30% of detected metabolites differentially expressed in response to activation were unique to HCA-positive CD4+ T lymphocytes; 3) metabolic pathways associated with glutathione detoxification and tryptophan degradation were altered in HCA-positive CD4+ T lymphocytes; and 4) flow cytometry and cytokine analyses suggested a bias toward a TH1-biased immune response in HCA-positive samples. HCA exposure primes the neonatal adaptive immune processes by inducing changes to the exometabolomic profile of fetal CD4+ T lymphocytes. These exometabolomic changes may link HCA exposure to TH1 polarization of the neonatal adaptive immune response.