The developing human preterm neonatal immune system: a case for more research in this area

Comparative Analysis of Global Gene Expression and Complement Components Levels in Umbilical Cord Blood from Preterm and Term Neonates: Implications for Significant Downregulation of Immune Response Pathways related to Prematurity

Background: Preterm birth is the most frequent cause of neonatal death, but its aetiology remains unclear. It has been suggested that the imbalance of immunological mechanisms responsible for maintaining pregnancy is contributing to preterm birth pathogenesis. We aimed to investigate global gene expression and the levels of several complement system components in umbilical cord blood samples from preterm neonates and compare them to term newborns. We sought to examine how differentially expressed genes could affect various immune-related pathways that are believed to be crucial factors in preterm birth. Material and methods: We enrolled 27 preterm infants (<37 weeks GA) and 52 term infants (>37 weeks GA), from which umbilical cord blood samples were collected. From these samples, peripheral blood mononuclear cells were isolated and subsequent RNA isolation was performed. We used Affymetrix Human Gene 2.1 ST Array Strip for microarray experiment and DAVID resources for bioinformatics analysis of the obtained data. Concentrations of C2, C3a, C5/C5a, C9, FactorD, Properdin were measured in umbilical cord blood plasma samples using multiplex fluorescent bead-based immunoassays using Luminex technology. Results: The levels of C3a and C5/5a were significantly elevated in preterm neonates compared to term babies, whereas C9 concentration was evidently increased in term infants. The expression of 250 genes was upregulated at least 2-fold and 3781 genes were downregulated at least 2-fold in preterm neonates in comparison with term infants. Functional annotation analysis revealed that in preterm infants in comparison to term babies there was a significant downregulation of genes encoding several Toll-like receptors, interleukins and genes involved in major signalling pathways (e.g. NF-κB, MAPK, TNF, Notch, JAK) and vital cellular processes (e.g. intracellular signal transduction, protein ubiquitination, protein transport, RNA splicing, DNA-templated transcription). Conclusions: Preterm birth results in immediate and long-term complications. Our results indicate that infants born prematurely show significant differences in complement components concentration and a downregulation of over 3,000 genes, involved mainly in various immune-related pathways, including innate immune response, phagocytosis and TLR function, when compared to full-term babies. Further studies on larger cohorts are needed to elucidate the role of immunity in prematurity.

Association of Long-Term Risk of Respiratory, Allergic, and Infectious Diseases With Removal of Adenoids and Tonsils in Childhood

Importance

Surgical removal of adenoids and tonsils to treat obstructed breathing or recurrent middle-ear infections remain common pediatric procedures; however, little is known about their long-term health consequences despite the fact that these lymphatic organs play important roles in the development and function of the immune system.

Objective

To estimate long-term disease risks associated with adenoidectomy, tonsillectomy, and adenotonsillectomy in childhood.

Design, Setting, and Participants

A population-based cohort study of up to 1 189 061 children born in Denmark between 1979 and 1999 and evaluated in linked national registers up to 2009, covering at least the first 10 and up to 30 years of their life, was carried out. Participants in the case and control groups were selected such that their health did not differ significantly prior to surgery.

Exposures

Participants were classified as exposed if adenoids or tonsils were removed within the first 9 years of life.

Main Outcomes and Measures

The incidence of disease (defined by International Classification of Diseases, Eighth Revision [ICD-8] and Tenth Revision [ICD-10] diagnoses) up to age 30 years was examined using stratified Cox proportional hazard regressions that adjusted for 18 covariates, including parental disease history, pregnancy complications, birth weight, Apgar score, sex, socioeconomic markers, and region of Denmark born.

Results

A total of up to 1 189 061 children were included in this study (48% female); 17 460 underwent adenoidectomy, 11 830 tonsillectomy, and 31 377 adenotonsillectomy; 1 157 684 were in the control group. Adenoidectomy and tonsillectomy were associated with a 2- to 3-fold increase in diseases of the upper respiratory tract (relative risk [RR], 1.99; 95% CI, 1.51-2.63 and RR, 2.72; 95% CI, 1.54-4.80; respectively). Smaller increases in risks for infectious and allergic diseases were also found: adenotonsillectomy was associated with a 17% increased risk of infectious diseases (RR, 1.17; 95% CI, 1.10-1.25) corresponding to an absolute risk increase of 2.14% because these diseases are relatively common (12%) in the population. In contrast, the long-term risks for conditions that these surgeries aim to treat often did not differ significantly and were sometimes lower or higher.

Conclusions and Relevance

In this study of almost 1.2 million children, of whom 17 460 had adenoidectomy, 11 830 tonsillectomy, and 31 377 adenotonsillectomy, surgeries were associated with increased long-term risks of respiratory, infectious, and allergic diseases. Although rigorous controls for confounding were used where such data were available, it is possible these effects could not be fully accounted for. Our results suggest it is important to consider long-term risks when making decisions to perform tonsillectomy or adenoidectomy.

Dissecting the defects in the neonatal CD8+ T-cell response

The neonatal period presents a complex scenario where the threshold of reactivity toward colonizing microbiota, maternal antigens, autoantigens, and pathogens must be carefully moderated and balanced. CD8⁺ T cells are critical for the response against intracellular bacteria and viruses, but this immune compartment maintains altered function relative to adult counterparts because of the unique challenges which infants face. Here, we review our current understanding of the factors which may promote the attenuation and altered function of the neonatal CD8⁺ T-cell response and potential avenues for future study. Specifically, we have focused on the neonatal CD8⁺ T-cell ontogeny, memory formation, TCR structure and repertoire, TCR inhibitory receptors, and the clinical implications of altered neonatal CD8⁺ T-cell function. Special emphasis has been placed on examining the response of preterm neonates relative to term neonates and adults.

Stereotypic Immune System Development in Newborn Children

Epidemiological data suggest that early life exposures are key determinants of immune-mediated disease later in life. Young children are also particularly susceptible to infections, warranting more analyses of immune system development early in life. Such analyses mostly have been performed in mouse models or human cord blood samples, but these cannot account for the complex environmental exposures influencing human newborns after birth. Here, we performed longitudinal analyses in 100 newborn children, sampled up to 4 times during their first 3 months of life. From 100 μL of blood, we analyze the development of 58 immune cell populations by mass cytometry and 267 plasma proteins by immunoassays, uncovering drastic changes not predictable from cord blood measurements but following a stereotypic pattern. Preterm and term children differ at birth but converge onto a shared trajectory, seemingly driven by microbial interactions and hampered by early gut bacterial dysbiosis.

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Cord blood is not representative of postnatal immunity

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Preterm and term children differ at birth but rapidly converge thereafter

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Immune system development follows a stereotypic pattern early in life

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Dynamic parameters imply microbial interactions during early immune development

Perspectives for Clinical Translation of Adipose Stromal/Stem Cells

Adipose stromal/stem cells (ASCs) are an ideal cell type for regenerative medicine applications, as they can easily be harvested from adipose tissue in large quantities. ASCs have excellent proliferation, differentiation, and immunoregulatory capacities that have been demonstrated in numerous studies. Great interest and investment have been placed in efforts to exploit the allogeneic use and immunomodulatory and anti-inflammatory effects of ASCs. However, bridging the gap between in vitro and in vivo studies and moving into clinical practice remain a challenge. For the clinical translation of ASCs, several issues must be considered, including how to characterise such a heterogenic cell population and how to ensure their safety and efficacy. This review explores the different phases of in vitro and preclinical ASC characterisation and describes the development of appropriate potency assays. In addition, good manufacturing practice requirements are discussed, and cell-based medicinal products holding marketing authorisation in the European Union are reviewed. Moreover, the current status of clinical trials applying ASCs and the patent landscape in the field of ASC research are presented. Overall, this review highlights the applicability of ASCs for clinical cell therapies and discusses their potential.

D-mannose-Coating of Maghemite Nanoparticles Improved Labeling of Neural Stem Cells and Allowed Their Visualization by ex vivo MRI after Transplantation in the Mouse Brain

Magnetic resonance imaging (MRI) of superparamagnetic iron oxide-labeled cells can be used as a non-invasive technique to track stem cells after transplantation. The aim of this study was to (1) evaluate labeling efficiency of D-mannose-coated maghemite nanoparticles (D-mannose(γ-Fe2O3)) in neural stem cells (NSCs) in comparison to the uncoated nanoparticles, (2) assess nanoparticle utilization as MRI contrast agent to visualize NSCs transplanted into the mouse brain, and (3) test nanoparticle biocompatibility. D-mannose(γ-Fe2O3) labeled the NSCs better than the uncoated nanoparticles. The labeled cells were visualized by ex vivo MRI and their localization subsequently confirmed on histological sections. Although the progenitor properties and differentiation of the NSCs were not affected by labeling, subtle effects on stem cells could be detected depending on dose increase, including changes in cell proliferation, viability, and neurosphere diameter. D-mannose coating of maghemite nanoparticles improved NSC labeling and allowed for NSC tracking by ex vivo MRI in the mouse brain, but further analysis of the eventual side effects might be necessary before translation to the clinic.

Early Life Respiratory Syncytial Virus Infection and Asthmatic Responses

The infant's developing immune response is central to establishing a balanced system that reacts appropriately to infectious stimuli, but does not induce altered disease states with potential long-term sequelae. Respiratory syncytial virus may alter the immune system, affecting future responses. Early infection may have direct effects on the lung itself. Other early life processes contribute to the development of immune responses including assembly of the microbiome, which seems to have a particularly important role for establishing the immune environment. This review covers studies that have set up important paradigms and discusses recent data that direct research toward informative hypotheses.

Prospective evaluation of diagnostic tools for respiratory viruses in children and adults

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Molecular techniques have considerably improved sensitivity of viral diagnosis.

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Interpretation of results can be delicate as DNA or RNA traces can be detected.

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Their use is hindered by their cost and the difficulty to absorb high workloads.

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Their impact in management of patients still has to be demonstrated.

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Tertiary care hospitals should provide a testing algorithm to suit each case.

Aim

To compare the performances of molecular and non-molecular tests to diagnose respiratory viral infections and to evaluate the pros and contras of each technique.

Methods

Two hundred ninety-nine respiratory samples were prospectively explored using multiplex molecular techniques (FilmArray Respiratory Panel, Clart Pneumovir), immunological techniques (direct fluorescent assay, lateral flow chromatography) and cell cultures.

Findings

Molecular techniques permitted the recovery of up to 50% more respiratory pathogens in comparison to non-molecular methods. FilmArray detected at least 30% more pathogens than Clart Pneumovir which could be explained by the differences in their technical designs. The turnaround time under 2 hours for the FilmArray permitted delivery of results when patients were still in the emergency room.

RSV prophylaxis in premature infants

Infants born prematurely before 37 weeks of gestational age (GA) have particular anatomical, immunological and metabolic characteristics that predispose them, even in the absence of diseases at birth, to severe morbidity. Respiratory syncytial virus (RSV) is the leading cause of hospitalization for lower respiratory tract infections (LRTI) in the first year of life, as well as an important cause of respiratory outcomes as recurrent wheezing in industrialized countries or mortality in developing countries. Prematurity is an important risk factor for hospitalization for severe RSV disease, but epidemiological, environmental and demographic risk factors also play a role in RSV infection. Currently, there is no effective antiviral therapy for the treatment of RSV infection, nor the possibility of using maternal immunization or vaccination of children to prevent infection, although numerous preclinical and clinical studies are still ongoing. Passive immunization with palivizumab has been shown to be safe and effective in preventing RSV hospitalization in children at greater risk of contracting a serious infection. Costs associated with palivizumab prophylaxis and its monthly intramuscularly administration has prompted many health institutions of different countries to implement specific recommendations, with the aim of protecting at risk infants for whom RSV infection is likely to cause serious illness or death. The cost-effectiveness ratio of prophylaxis, related to reduce hospitalization costs and the impact of the burden of RSV disease worldwide, greatly affects the drafting and the adoption of specific recommendations and the adherence to them, concerning the passive immunization with palivizumab.

Impact of prematurity for pancreatic islet and beta-cell development

As increasing numbers of babies born preterm survive into adulthood, it is becoming clear that, in addition to the well-described risks of neurodevelopmental sequelae, there also are increased risks for non-communicable diseases, including diabetes. Epidemiological studies indicate that risks are increased even for birth at late preterm and early term gestations and for both type 1 and type 2 diabetes. Thus, factors related to preterm birth likely affect development of the fetal and neonatal beta-cell in addition to effects on peripheral insulin sensitivity. These factors could operate prior to preterm birth and be related to the underlying cause of preterm birth, to the event of being born preterm itself, to the postnatal care of the preterm neonate or to a combination of these exposures. Experimental evidence indicates that factors may be operating during all these critical periods to contribute to altered development of beta-cell mass in those born preterm. Greater understanding of how these factors impact upon development of the pancreas may lead to interventions or management approaches that mitigate the increased risk of later diabetes.

Expression of FcRn receptor in placental tissue and its relationship with IgG levels in term and preterm newborns

PROBLEM

IgG is the only antibody class, that is, actively transferred from the mother to the fetus across the placenta by an active, neonatal Fc receptor (FcRn) mediated process during pregnancy, conferring passive immunity and protection against infections to the newborn during the first months of life. Preterm infants may not receive sufficient titers of protective antibodies, as most of them are transferred only after the 34th week of gestation. Because of the great importance of this process, we investigated in a clinical setting the placental transmission of IgG antibodies in term and preterm newborns.

METHOD OF STUDY

This work was conducted in 85 woman and their newborns, divided into four groups according to their clinical gestational age (≤37 weeks were considered as preterm). Blood samples were collected from the mothers and their newborns' umbilical cords to analyze total serum IgG concentrations, and a subgroup of 32 placentas was analyzed by immunohistochemistry to quantify the expression of the FcRn receptor.

RESULTS

Total IgG levels in both mothers and neonates increased significantly through the third trimester of gestation. Regarding the newborns, in all groups, IgG levels exceeded their mother's values by a ~2.4%. A higher expression of FcRn was detected in placentas from newborns at week 36 of gestation onwards.

CONCLUSION

Our results obtained from clinical samples, were in line with previous descriptions in model systems and confirmed that the IgG transfer from maternal serum to the fetus is positively correlated with FcRn expression in placental tissue throughout gestation.

A comparative analysis of immune privilege in pregnancy and cancer in the context of checkpoint blockade immunotherapy

Despite their abilities to elicit immune responses, both syngeneic tumors and the half-mismatched placenta grow in the host, unlike a tissue allograft that is aggressively rejected. This is because of local and systemic factors that contribute to the immunologic privilege of tumors and the placenta. Checkpoint blockade immunotherapies subvert this privilege, with spectacularly beneficial outcomes in subsets of patients with certain types of cancer. A challenge for the community of scientists and clinicians is to replicate these successes in pregnant patients with cancer, without harm to the placenta. Here we compare and contrast the immunology of cancers and the placenta, and suggest that immunotherapy for pregnant patients with cancer may be a reasonable option, but that this should be explored systematically.

[Research advances in immune tolerance of allogeneic cell transplantation in preterm infants]

Preterm infants are a special group, and related severe neurological, respiratory, and digestive disorders have high disability/fatality rates. Allogeneic cell transplantation may be an effective method for the prevention and treatment of these diseases. At present, animal studies have been conducted for allogeneic cell transplantation in the treatment of hypoxic-ischemic encephalopathy, bronchopulmonary dysplasia, and necrotizing enterocolitis. The main difficulty of this technique is graft-versus-host reaction (GVHR), and successful induction of immune tolerance needs to be achieved in order to solve this problem. This article reviews the research advances in immune tolerance of allogeneic cell transplantation in preterm infants.

CD71+ erythroid cells from neonates born to women with preterm labor regulate cytokine and cellular responses

Neonatal CD71+ erythroid cells are thought to have immunosuppressive functions. Recently, we demonstrated that CD71+ erythroid cells from neonates born to women who underwent spontaneous preterm labor (PTL) are reduced to levels similar to those of term neonates; yet, their functional properties are unknown. Herein, we investigated the functionality of CD71+ erythroid cells from neonates born to women who underwent spontaneous preterm or term labor. CD71+ erythroid cells from neonates born to women who underwent PTL displayed a similar mRNA profile to that of those from term neonates. The direct contact between preterm or term neonatal CD71+ erythroid cells and maternal mononuclear immune cells, but not soluble products from these cells, induced the release of proinflammatory cytokines and a reduction in the release of TGF-β. Moreover, PTL-derived neonatal CD71+ erythroid cells (1) modestly altered CD8+ T cell activation; (2) inhibited conventional CD4+ and CD8+ T-cell expansion; (3) suppressed the expansion of CD8+ regulatory T cells; (4) regulated cytokine responses mounted by myeloid cells in the presence of a microbial product; and (5) indirectly modulated T-cell cytokine responses. In conclusion, neonatal CD71+ erythroid cells regulate neonatal T-cell and myeloid responses and their direct contact with maternal mononuclear cells induces a proinflammatory response. These findings provide insight into the biology of neonatal CD71+ erythroid cells during the physiologic and pathologic processes of labor.

Inflammasome function in monocyte subsets and a risk of late-onset sepsis in preterm very low birth weight neonates

BACKGROUND

Immature immune systems predispose very low birth weight (VLBW) neonates to systemic infections in early life. Defective inflammasome function may increase a neonate's susceptibility to late-onset sepsis (LOS).

METHODS

Blood samples were taken on the 5^th day of life (DOL) for all VLBW neonates (non-LOS and before-LOS groups; N.=76), and within 24 hours of sepsis onset (LOS group; N.=39). Monocyte (MO) subsets and intracellular interleukin-1β (IL-1β) expression were analyzed using flow cytometry. Inflammasome function, defined as level of IL-1β and interleukin-18 (IL-18) was measured with enzyme-linked immunosorbent assay. IRA B cells were reported as a fraction of all B cells.

RESULTS

Stimulation of classical MO in non-LOS cells demonstrated a higher expression of intracellular IL-1β in comparison to MO from before LOS group. Serum from the LOS group revealed a higher level of IL-18. Stimulation of mononuclear cultures from samples taken during LOS resulted in significantly increased supernatant level of IL-1β and IL-18 in comparison to samples taken on 5^th DOL. No changes in the levels of IRA B cells were detected with the onset of sepsis.

CONCLUSIONS

We did not observe a difference in the functioning of the inflammasome within monocytes taken on 5^th DOL from premature VLBW neonates. Furthermore, there was no observable change in the IRA B cells of the septic and non-septic groups. The decreased expression of intracellular IL-1β within classical MO of the before-LOS group may be an independent risk factor for LOS development.

Non-digestible carbohydrates in infant formula as substitution for human milk oligosaccharide functions: Effects on microbiota and gut maturation

Human milk (HM) is the golden standard for nutrition of newborn infants. Human milk oligosaccharides (HMOs) are abundantly present in HM and exert multiple beneficial functions, such as support of colonization of the gut microbiota, reduction of pathogenic infections and support of immune development. HMO-composition is during lactation continuously adapted by the mother to accommodate the needs of the neonate. Unfortunately, for many valid reasons not all neonates can be fed with HM and are either totally or partly fed with cow-milk derived infant formulas, which do not contain HMOs. These cow-milk formulas are supplemented with non-digestible carbohydrates (NDCs) that have functional effects similar to that of some HMOs, since production of synthetic HMOs is challenging and still very expensive. However, NDCs cannot substitute all HMO functions. More efficacious NDCs may be developed and customized for specific groups of neonates such as pre-matures and allergy prone infants. Here current knowledge of HMO functions in the neonate in view of possible replacement of HMOs by NDCs in infant formulas is reviewed. Furthermore, methods to expedite identification of suitable NDCs and structure/function relationships are reviewed as in vivo studies in babies are impossible.

Sepsis-Induced Immunosuppression in Neonates

Neonates, especially those born preterm, are at increased risk of sepsis and adverse long-term effects associated with infection-related inflammation. Distinct neonatal immune responses and dysregulated inflammation are central to this unique susceptibility. The traditional separation of sepsis into an initial hyper-inflammatory response followed by hypo-inflammation is continually under review with new developments in this area of research. There is evidence to support the association of mortality in the early acute phase of sepsis with an overwhelming hyper-inflammatory immune response. Emerging evidence from adults suggests that hypo- and hyper-inflammation can occur during any phase of sepsis and that sepsis-immunosuppression is associated with increased mortality, morbidity, and risk to subsequent infection. In adults, sepsis-induced immunosuppression (SII) is characterised by alterations of innate and adaptive immune responses, including, but not limited to, a prominent bias toward anti-inflammatory cytokine secretion, diminished antigen presentation to T cells, and reduced activation and proliferation of T cells. It is unclear if sepsis-immunosuppression also plays a role in the adverse outcomes associated with neonatal sepsis. This review will focus on exploring if key characteristics associated with SII in adults are observed in neonates with sepsis.

Newborn susceptibility to infection vs. disease depends on complex in vivo interactions of host and pathogen

The burden of newborn infectious disease has long been recognized as the highest across the entire human life span. The precise underlying cause is unfortunately still far from clear. A substantial body of data derived mostly from in vitro experimentation indicates "lower" host immune responses in early vs. adult life and is briefly summarized within this review. However, emerging data derived mostly from in vivo experimentation reveal that the newborn host also exhibits an exuberant immune and inflammatory response following infection when compared to the adult. In this context, it is important to emphasize that "infection" does not equate "infectious disease," as for many infections it is the host response to the infection that causes disease. This simple insight readily arranges existing evidence into cause-effect relationships that explain much of the increase in clinical suffering from infection in early life. We here briefly summarize the evidence in support of this paradigm and highlight the important implications it has for efforts to ameliorate the suffering and dying from infection in early life.

Preterm Birth Affects the Risk of Developing Immune-Mediated Diseases

Prematurity affects approximately 10% of all children, resulting in drastically altered antigen exposure due to premature confrontation with microbes, nutritional antigens, and other environmental factors. During the last trimester of pregnancy, the fetal immune system adapts to tolerate maternal and self-antigens, while also preparing for postnatal immune defense by acquiring passive immunity from the mother. Since the perinatal period is regarded as the most important “window of opportunity” for imprinting metabolism and immunity, preterm birth may have long-term consequences for the development of immune-mediated diseases. Intriguingly, preterm neonates appear to develop bronchial asthma more frequently, but atopic dermatitis less frequently in comparison to term neonates. The longitudinal study of preterm neonates could offer important insights into the process of imprinting for immune-mediated diseases. On the one hand, preterm birth may interrupt influences of the intrauterine environment on the fetus that increase or decrease the risk of later immune disease (e.g., maternal antibodies and placenta-derived factors), whereas on the other hand, it may lead to the premature exposure to protective or harmful extrauterine factors such as microbiota and nutritional antigen. Solving this puzzle may help unravel new preventive and therapeutic approaches for immune diseases.

Surge of immune cell formation at birth differs by mode of delivery and infant characteristics-A population-based cohort study

BACKGROUND

Birth by cesarean section is associated with increased risks of immune disorders. We tested whether establishment of immune function at birth relates to mode of delivery, taking other maternal and infant characteristics into account.

METHODS AND FINDINGS

Using a prospectively collected database, we retrieved information on maternal and infant characteristics of 6,014 singleton infants delivered from February to April 2014 in Stockholm, Sweden, with gestational age ≥35 weeks, Apgar scores ≥7, and without congenital malformations or any neonatal morbidity. We linked our data to blood levels of T-cell receptor excision circles (TREC) and κ-deleting recombination excision circles (KREC), determined as part of a neonatal screening program for immune-deficiencies, and representing quantities of newly formed T- and B-lymphocytes. Multivariate logistic regression was used to calculate odds ratios (OR) with 95% confidence intervals (CI) for participants having TREC and KREC levels in the lowest quintile. Multivariate models were adjusted for postnatal age at blood sampling, and included perinatal (mode of delivery, infant sex, gestational age, and birth weight for gestational age), and maternal characteristics (age, parity, BMI, smoking, diabetes, and hypertensive disease). Low TREC was associated with cesarean section before labor (adjusted OR:1.32 [95% CI 1.08-1.62]), male infant sex (aOR:1.60 [1.41-1.83]), preterm birth at 35-36 weeks of gestation (aOR:1.89 [1.21-2.96]) and small for gestational age (aOR:1.67 [1.00-2.79]). Low KREC was associated with male sex (aOR:1.32 [1.15-1.50]), postterm birth at ≥42 weeks (aOR:1.43 [1.13-1.82]) and small for gestational age (aOR:2.89 [1.78-4.69]). Maternal characteristics showed no consistent associations with neonatal levels of either TREC or KREC.

CONCLUSION

Cesarean section before labor was associated with lower T-lymphocyte formation, irrespective of maternal characteristics, pregnancy, and neonatal risk factors. The significance of a reduced birth-related surge in lymphocyte formation for future immune function and health remains to be investigated.

Protecting the Newborn and Young Infant from Infectious Diseases: Lessons from Immune Ontogeny

Infections in the first year of life are common and often severe. The newborn host demonstrates both quantitative and qualitative differences to the adult in nearly all aspects of immunity, which at least partially explain the increased susceptibility to infection. Here we discuss how differences in susceptibility to infection result not out of a state of immaturity, but rather reflect adaptation to the particular demands placed on the immune system in early life. We review the mechanisms underlying host defense in the very young, and discuss how specific developmental demands increase the risk of particular infectious diseases. In this context, we discuss how this plasticity, i.e. the capacity to adapt to demands encountered in early life, also provides the potential to leverage protection of the young against infection and disease through a number of interventions.

Immune response of toddlers with history of prematurity

BACKGROUND

It is not quite well established how immune responses differ in term and preterm infants beyond the first year of life. This study aimed to evaluate aspects of the innate and adaptive immune responses in a group of preterm infants in comparison with their term peers.

METHODS

In this cross-sectional study peripheral blood mononuclear cells (PBMC) were isolated from preterm and term children at age three years. Innate immune response was evaluated by the analysis of TLR receptors expression on CD11c⁺HLADR^high cells and inflammatory cytokine production after PBMC stimulation with Toll like receptors (TLR) ligands. Adaptive immune response was evaluated by T cells' phenotyping and function after stimulation with polyclonal conventional T cell stimulus.

CONCLUSION

We have found that the patterns of innate and adaptive immune responses at 3 years of age were not affected by the fact of the children having being born preterm or at term.

[Rhinovirus: Underestimated pathogens in patients during the neonatal period]

INTRODUCTION

In recent years, developments in virological tools have led to the easy detection of rhinoviruses and enteroviruses (E/RV). Their detection is very frequent in cases of airway involvement in children and their demonstrated causality. But the morbidity of E/RV in the neonatal period is unknown due to lack of epidemiological data. The objective of this study was to evaluate the incidence and clinical characteristics of these infections in hospitalized neonates.

MATERIALS AND METHODS

We retrospectively analyzed the virology specimens of all neonates hospitalized at the Caen University Hospital between 2006 and 2011. Clinical characteristics were obtained from the charts.

RESULTS

During the study period, 4544 infants aged less than 28 days were hospitalized: 4159 in the neonatal ward and 385 in the pediatric ward. Among these, 711 virology specimens were available, 31 % of which identified at least one virus. An E/RV was identified in 87 patients (1.9 % of the neonates admitted during the study period): 52 in the pediatric ward (13.5 % of 385), and 35 in the neonatal ward (0.8 % of 4159). The mean gestational age was 39 weeks in the pediatric cohort and 35 weeks in the neonatal cohort. The main indication for virological analysis was persistent drowsiness (28 %), temperature above 38°C (25 %), an apparently life-threatening event (23 %), bradycardia (20.5 %), and pallor (20.5 %). Respiratory symptoms associated with E/RV infection were coryza (74 %), cough (35 %), hypoxemia (32 %), accessory muscle use, and recession (31 %). Digestive symptoms were poor feeding (59 %), regurgitation (38 %), abdominal distension (24 %), and projectile vomiting (17 %). Twenty-three percent of the patients required admission to the neonatal ICU or pediatric ICU. Respiratory treatments included oxygen (24 % of 87 patients), continuous positive airway pressure (11 %), and ventilation (5 %). Antibiotics were prescribed in 41 % of the patients (46), but only 10 % (9) had an identified concomitant bacterial infection. In the neonatal department, nosocomial acquisition was suspected in 50 % of E/RV infections.

CONCLUSION

E/RV infections have a significant morbidity in neonates, and nosocomial transmission of the virus is underestimated. We recommend that respiratory viruses, including E/RV, be tested for in any unexplained signs in a neonate. Better identification of viruses might shorten the duration of unnecessary antibiotics.

Plasma cell and serum antibody responses to influenza vaccine in preterm and full-term infants

BACKGROUND

Preterm (PT) infants are at greater risk for severe influenza infection and experience decrements in long-term antibody responses to vaccines. This may related to defects in antibody secreting cell (ASC) generation.

OBJECTIVE

To investigate the relationships among the frequencies of influenza-specific antibody secreting cells, ASC numbers and subsets, and antibody responses to influenza vaccines (IV) among PT and full-term (FT) infants.

DESIGN/METHODS

We enrolled 11 former PT (≤32weeks' gestation, ≤1500 g' birth weight) and 11FT infants, 6-17months of age, receiving their first influenza immunizations. Infants received two doses of inactivated trivalent (T)IV or quadrivalent (Q)IV during the 2012-2013 and 2013-2014 influenza seasons, respectively, at 0 and 28days, and blood was drawn at 0, 10, 35, and 56days and 9months. Vaccine-specific antibody was measured by hemagglutination inhibition (HAI) at 0 and 56days and 9months, vaccine-specific ASC numbers by enzyme linked immunospot (ELISPOT) at 10 and 35days, and ASC subsets by flow cytometry at 0, 10 and 35days.

RESULTS

PT infants had post-vaccine HAI titers to all 4 vaccine strains at least equal to FT infants at 56days and 9months after beginning immunization. Influenza-specific ASC ELISPOT responses at 35days were higher among PT than FT infants (median 100 v. 30 per 10⁶ PBMC, p=0.04). ASC numbers at 35days were positively correlated with serum HAI titers at 56days (ρ=0.50-0.80). There were no statistical differences between PT and FT infants in the frequency of five ASC subsets and no specific ASC subset correlated with durability of serum antibody titers.

CONCLUSIONS

Influenza-specific ASC numbers in both FT and PT infants correlated with peak antibody titers, but ASC subsets did not correlate with durability of antibody response.

Neonatal infection produces significant changes in immune function with no associated learning deficits in juvenile rats

The current experiments examined the impact of early-life immune activation and a subsequent mild immune challenge with lipopolysaccharide (LPS; 25µg/kg) on hippocampal-dependent learning, proinflammatory cytokine expression in the brain, and peripheral immune function in juvenile male and female rats at P24, an age when hippocampal-dependent learning and memory first emerges. Our results indicate that neonatal infection did not produce learning deficits in the hippocampal-dependent context pre-exposure facilitation effect paradigm in juvenile males and females, contrary to what has been observed in adults. Neonatal infection produced an increase in baseline IL-1β expression in the hippocampus (HP) and medial prefrontal cortex (mPFC) of juvenile rats. Furthermore, neonatally infected rats showed exaggerated IL-1β expression in the HP following LPS treatment as juveniles; and juvenile females, but not males, showed exaggerated IL-1β expression in the mPFC following LPS treatment. Neonatal infection attenuated the production of IL-6 expression following LPS treatment in both the brain and the spleen, and neonatal infection decreased the numbers of circulating white blood cells in juvenile males and females, an effect that was further exacerbated by subsequent LPS treatment. Together, our data indicate that the consequences of neonatal infection are detectable even early in juvenile development, though we found no concomitant hippocampal-dependent learning deficits at this young age. These findings underscore the need to consider age and associated on-going neurodevelopmental processes as important factors contributing to the emergence of cognitive and behavioral disorders linked to early-life immune activation. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1221-1236, 2017.

Immune responses in perinatal brain injury

The perinatal period has often been described as immune deficient. However, it has become clear that immune responses in the neonate following exposure to microbes or as a result of tissue injury may be substantial and play a role in perinatal brain injury. In this article we will review the immune cell composition under normal physiological conditions in the perinatal period, both in the human and rodent. We will summarize evidence of the inflammatory responses to stimuli and discuss how neonatal immune activation, both in the central nervous system and in the periphery, may contribute to perinatal hypoxic-ischemic brain injury.

Guidance on the risk assessment of substances present in food intended for infants below 16 weeks of age

Following a request from the European Commission to EFSA, the EFSA Scientific Committee (SC) prepared a guidance for the risk assessment of substances present in food intended for infants below 16 weeks of age. In its approach to develop this guidance, the EFSA SC took into account, among others, (i) an exposure assessment based on infant formula as the only source of nutrition; (ii) knowledge of organ development in human infants, including the development of the gut, metabolic and excretory capacities, the brain and brain barriers, the immune system, the endocrine and reproductive systems; (iii) the overall toxicological profile of the substance identified through the standard toxicological tests, including critical effects; (iv) the relevance for the human infant of the neonatal experimental animal models used. The EFSA SC notes that during the period from birth up to 16 weeks, infants are expected to be exclusively fed on breast milk and/or infant formula. The EFSA SC views this period as the time where health-based guidance values for the general population do not apply without further considerations. High infant formula consumption per body weight is derived from 95th percentile consumption. The first weeks of life is the time of the highest relative consumption on a body weight basis. Therefore, when performing an exposure assessment, the EFSA SC proposes to use the high consumption value of 260 mL/kg bw per day. A decision tree approach is proposed that enables a risk assessment of substances present in food intended for infants below 16 weeks of age. The additional information needed when testing substances present in food for infants below 16 weeks of age and the approach to be taken for the risk assessment are on a case-by-case basis, depending on whether the substance is added intentionally to food and is systemically available.

Cord blood hematopoietic cells from preterm infants display altered DNA methylation patterns

Background

Premature infants are highly vulnerable to infection. This is partly attributable to the preterm immune system, which differs from that of the term neonate in cell composition and function. Multiple studies have found differential DNA methylation (DNAm) between preterm and term infants’ cord blood; however, interpretation of these studies is limited by the confounding factor of blood cell composition. This study evaluates the epigenetic impact of preterm birth in isolated hematopoietic cell populations, reducing the concern of cell composition differences.

Methods

Genome-wide DNAm was measured using the Illumina 450K array in T cells, monocytes, granulocytes, and nucleated red blood cells (nRBCs) isolated from cord blood of 5 term and 5 preterm (<31 weeks gestational age) newborns. DNAm of hematopoietic cells was compared globally across the 450K array and through site-specific linear modeling.

Results

Nucleated red blood cells (nRBCs) showed the most extensive changes in DNAm, with 9258 differentially methylated (DM) sites (FDR < 5%, |Δβ| > 0.10) discovered between preterm and term infants compared to the <1000 prematurity-DM sites identified in white blood cell populations. The direction of DNAm change with gestational age at these prematurity-DM sites followed known patterns of hematopoietic differentiation, suggesting that term hematopoietic cell populations are more epigenetically mature than their preterm counterparts. Consistent shifts in DNAm between preterm and term cells were observed at 25 CpG sites, with many of these sites located in genes involved in growth and proliferation, hematopoietic lineage commitment, and the cytoskeleton. DNAm in preterm and term hematopoietic cells conformed to previously identified DNAm signatures of fetal liver and bone marrow, respectively.

Conclusions

This study presents the first genome-wide mapping of epigenetic differences in hematopoietic cells across the late gestational period. DNAm differences in hematopoietic cells between term and <31 weeks were consistent with the hematopoietic origin of these cells during ontogeny, reflecting an important role of DNAm in their regulation. Due to the limited sample size and the high coincidence of prematurity and multiple births, the relationship between cause of preterm birth and DNAm could not be evaluated. These findings highlight gene regulatory mechanisms at both cell-specific and systemic levels that may be involved in fetal immune system maturation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-017-0339-1) contains supplementary material, which is available to authorized users.

Constant light exposure impairs immune tolerance development in mice

BACKGROUND

An intrinsic daily physiological rhythm called circadian rhythm has been indicated to affect the immune system and its related diseases. Immune tolerance development is closely associated with the onset of immunological disorders. However, the effect of circadian rhythm in the mechanisms of immune tolerance development has not yet been fully understood.

OBJECTIVE

The purpose of this study was to investigate the effects of circadian rhythm disruption on the development of immune tolerance by the perturbation of light environment, using a mouse model of neonatally induced cutaneous tolerance.

METHODS

Mice were kept under constant light (LL) or light-dark (LD) conditions, and hapten was applied at 2days after birth. Six weeks later, hapten was reapplied to abdominal skin, followed by hapten application to ear skin 5days later.

RESULTS

The ear-swelling responses and cell infiltration into inflamed skin significantly increased in LL mice compared with those in LD mice. Interestingly, the percentage and the number of Foxp3+-regulatory T cells notably decreased in inflamed skin and draining lymph nodes of LL mice compared with that in LD mice. Loss-of-function mutation of a key circadian gene, Bmal1, also exacerbated the ear-swelling responses and cell infiltration into inflamed skin in mice.

CONCLUSION

These results suggest that circadian rhythm may be implicated in immune tolerance development in allergic inflammation.

Antifungal Immunological Defenses in Newborns

Newborns are prone to fungal infections, largely due to Candida species. The immunological basis for this vulnerability is not yet fully understood. However, useful insights can be gained from the knowledge of the maturation of immune pathways during ontogeny, particularly when placed in context with how rare genetic mutations in humans predispose to fungal diseases. In this article, we review these most current data on immune functions in human newborns, highlighting pathways most relevant to the response to Candida. While discussing these data, we propose a framework of why deficiencies in these pathways make newborns particularly vulnerable to this opportunistic pathogen.

The Importance of Human Milk for Immunity in Preterm Infants

The immune system of preterm infants is immature, placing them at increased risk for serious immune-related complications. Human milk provides a variety of immune protective and immune maturation factors that are beneficial to the preterm infant's poorly developed immune system. The most studied immune components in human milk include antimicrobial proteins, maternal leukocytes, immunoglobulins, cytokines and chemokines, oligosaccharides, gangliosides, nucleotides, and long-chain polyunsaturated fatty acids. There is growing evidence that these components contribute to the lower incidence of immune-related conditions in the preterm infant. Therefore, provision of these components in human milk, donor milk, or formula may provide immunologic benefits.

Antibiotic Treatment and Length of Hospital Stay in Relation to Delivery Mode and Prematurity

Aim

To investigate how 1) maternal delivery mode and 2) prematurity in infants are associated to antibiotic treatment and length of hospital stay.

Methods

Women having given birth and infants 0–12 months discharged from hospital between July 2005 and November 2011 were identified from the Swedish National Patient Register. Medical records were reviewed for 203 women and 527 infants. The risk ratio (RR) between antibiotic treatment and 1) delivery mode in women; 2) prematurity in infants was calculated. Length of stay and days of antibiotic therapy were compared by Wilcoxon rank-sum test.

Results

Women: There was an association between emergency caesarean section (CS) and antibiotic treatment (RR 5.0 95% confidence interval (CI) 2.2–11.5), but not for elective CS. Length of stay was longer for CS (emergency and elective) compared to vaginal delivery (p<0.01). Infants: RR for antibiotic treatment in preterm compared to term infants was 1.4 (95% CI 1.0–1.9). Length of stay (p<0.01), but not days of therapy (p = 0.17), was higher in preterm compared to term infants.

Conclusion

We found that emergency CS increased the probability of maternal antibiotic treatment during hospitalisation, but no difference was found between term and preterm infants. The results are well aligned with current guidelines and may be considered in future studies on the effects of antibiotics.

Neonatal monocytes exhibit a unique histone modification landscape

Background

Neonates have dampened expression of pro-inflammatory cytokines and difficulty clearing pathogens. This makes them uniquely susceptible to infections, but the factors regulating neonatal-specific immune responses are poorly understood. Epigenetics, including histone modifications, can activate or silence gene transcription by modulating chromatin structure and stability without affecting the DNA sequence itself and are potentially modifiable. Histone modifications are known to regulate immune cell differentiation and function in adults but have not been well studied in neonates.

Results

To elucidate the role of histone modifications in neonatal immune function, we performed chromatin immunoprecipitation on mononuclear cells from 45 healthy neonates (gestational ages 23–40 weeks). As gestation approached term, there was increased activating H3K4me3 on the pro-inflammatory IL1B, IL6, IL12B, and TNF cytokine promoters (p < 0.01) with no change in repressive H3K27me3, suggesting that these promoters in preterm neonates are less open and accessible to transcription factors than in term neonates. Chromatin immunoprecipitation with massively parallel DNA sequencing (ChIP-seq) was then performed to establish the H3K4me3, H3K9me3, H3K27me3, H3K4me1, H3K27ac, and H3K36me3 landscapes in neonatal and adult CD14+ monocytes. As development progressed from neonate to adult, monocytes lost the poised enhancer mark H3K4me1 and gained the activating mark H3K4me3, without a change in additional histone modifications. This decreased H3K4me3 abundance at immunologically important neonatal monocyte gene promoters, including CCR2, CD300C, ILF2, IL1B, and TNF was associated with reduced gene expression.

Conclusions

These results provide evidence that neonatal immune cells exist in an epigenetic state that is distinctly different from adults and that this state contributes to neonatal-specific immune responses that leaves them particularly vulnerable to infections.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-016-0265-7) contains supplementary material, which is available to authorized users.

Schedules for Pneumococcal Vaccination of Preterm Infants: An RCT

BACKGROUND AND OBJECTIVE

Premature infants have a higher risk of invasive pneumococcal disease and are more likely to have lower vaccine responses compared with term infants. Increasingly, immunization schedules are including a reduced, 2-dose, pneumococcal conjugate vaccine priming schedule. Our goal was to assess the immunogenicity of 3 commonly used 13-valent pneumococcal conjugate vaccine (PCV13) priming schedules in premature infants and their response to a 12-month booster dose.

METHODS

Premature infants (<35 weeks' gestation) were randomized to receive PCV13 at 2 and 4 months (reduced schedule); 2, 3, and 4 months (accelerated schedule); or 2, 4, and 6 months (extended schedule). All infants received a 12-month PCV13 booster. Serotype-specific pneumococcal immunoglobulin G (IgG) for PCV13 serotypes was measured by using enzyme-linked immunosorbent assay 1 month after the primary and booster vaccinations.

RESULTS

A total of 210 infants (median birth gestation, 29(+6) weeks; range, 23(+2)-34(+6) weeks) were included. After the primary vaccination, 75% (95% confidence interval [CI], 62-85), 88% (95% CI, 76-95), and 97% (95% CI, 87-99) of participants had protective antibody concentrations for at least one-half the PCV13 serotypes for the reduced, accelerated, and extended schedules, respectively. After the booster vaccination, participants receiving the extended schedule had significantly lower (P < .05) geometric mean concentrations compared with reduced (for 9 of 13 serotypes) and accelerated (for 4 of 13 serotypes) schedules, but nearly all participations, regardless of schedule or serotype, had seroprotective IgG concentrations.

CONCLUSIONS

A reduced priming schedule of PCV13 resulted in higher post-booster IgG concentrations but lower post-primary concentrations. The optimum vaccine schedule for preterm infants will therefore depend on when they are most at risk for invasive pneumococcal disease.

Galectin-3 binding protein in human preterm infant umbilical cord plasma

BACKGROUND

Galectin-3 binding protein (Gal3BP) is a glycoprotein isolated in colostrum that may be an immunologically active component with effects on the neonatal immune system. This compound has been found in the blood of term newborn infants, but has not been studied in preterm infants.

OBJECTIVE

Compare umbilical cord plasma Gal3BP concentration between preterm and term infants.

STUDY DESIGN

Observational study of mother-infant pairs consented at UCSD Medical Center comparing umbilical cord plasma Gal3BP concentration in preterm and term infants. Umbilical cord plasma was collected at birth and stored at -80°C before Gal3BP analysis by ELISA. This study was powered to evaluate differences in preterm and term infant Gal3BP concentration. The secondary aim was to determine the effect of maternal and infant clinical factors on Gal3BP concentration.

RESULTS

A total of 64 preterm and 30 term umbilical cord plasma samples were analyzed. By univariate analysis, Gal3BP concentration was elevated in the setting of prematurity, maternal diabetes, antenatal steroid exposure, and increasing maternal parity (p <  0.05); and decreased in chorioamnionitis (p = 0.03). Using a multiple linear regression model prematurity, chorioamnionitis and maternal diabetes remained significant.

CONCLUSIONS

Umbilical cord plasma Gal3BP concentration is elevated in prematurity. This may reflect inflammatory states in infant and mother, but further study is warranted.

Changes in the Immune Components of Preterm Human Milk and Associations With Maternal and Infant Characteristics

OBJECTIVE

To describe difference in cytokines, chemokines, and growth factors (CCGFs) and secretory immunoglobulin A (sIgA) in the breast milk of mothers who gave birth preterm and maternal or infant characteristics related to these immune components.

DESIGN

A prospective, repeated-measures, one-group design.

SETTING

Data were collected at an 82-bed NICU in West Central Florida.

PARTICIPANTS

Seventy-six very-low-birth-weight infants weighing less than 1,500 g and their mothers.

METHODS

Daily aliquots of breast milk from mothers of preterm infants were collected from the daily infants' feedings and pooled at the end of each week, and CCGFs and sIgA were measured weekly with MagPix multiplexing (Luminex, Austin, TX) and enzyme-linked immunosorbent assay.

RESULTS

The CCGFs showed high individual variability, but the levels of most CCGFs and sIgA fell over time. Immune variables were generally greater in milk from mothers of infants smaller than 1,000 g. The breast milk of mothers of male preterm infants had significantly greater sIgA than the breast milk of mothers of female preterm infants. We found relationships between age, body mass index, parity, sIgA, and some of the CCGFs in the breast milk of women who gave birth preterm.

CONCLUSION

Immune molecules declined in concentration over time in the breast milk of mothers who give birth preterm during the NICU stay, and maternal and infant factors appeared to play some role in the levels of these immune molecules. Further exploration of this relationship is warranted.

The immunological landscape in necrotising enterocolitis

Necrotising enterocolitis (NEC) is an uncommon, but devastating intestinal inflammatory disease that predominantly affects preterm infants. NEC is sometimes dubbed the spectre of neonatal intensive care units, as its onset is insidiously non-specific, and once the disease manifests, the damage inflicted on the baby's intestine is already disastrous. Subsequent sepsis and multi-organ failure entail a mortality of up to 65%. Development of effective treatments for NEC has stagnated, largely because of our lack of understanding of NEC pathogenesis. It is clear, however, that NEC is driven by a profoundly dysregulated immune system. NEC is associated with local increases in pro-inflammatory mediators, e.g. Toll-like receptor (TLR) 4, nuclear factor-κB, tumour necrosis factor, platelet-activating factor (PAF), interleukin (IL)-18, interferon-gamma, IL-6, IL-8 and IL-1β. Deficiencies in counter-regulatory mechanisms, including IL-1 receptor antagonist (IL-1Ra), TLR9, PAF-acetylhydrolase, transforming growth factor beta (TGF-β)_1&2, IL-10 and regulatory T cells likely facilitate a pro-inflammatory milieu in the NEC-afflicted intestine. There is insufficient evidence to conclude a predominance of an adaptive Th1-, Th2- or Th17-response in the disease. Our understanding of the accompanying regulation of systemic immunity remains poor; however, IL-1Ra, IL-6, IL-8 and TGF-β₁ show promise as biomarkers. Here, we chart the emerging immunological landscape that underpins NEC by reviewing the involvement and potential clinical implications of innate and adaptive immune mediators and their regulation in NEC.

Components of the lectin pathway of complement activation in paediatric patients of intensive care units

Infections are a major cause of childhood mortality. We investigated components of the lectin pathway of complement activation in the context of sepsis at both genetic and protein levels in neonates, infants and older children. Major components of the lectin pathway and two genes for Toll-like receptors were studied in 87 neonates with confirmed sepsis and compared with 40 babies with infections who did not develop sepsis (disease controls) and 273 infection-free neonatal controls. A second cohort comprised 47 older children with sepsis and 87 controls. Low MBL-conferring genotypes (LXA/O+O/O) were more frequent in sepsis patients than in healthy controls but no significant differences in the frequency of SNPs of other lectin pathway genes (FCN1, FCN2, FCN3, MASP1/3, MASP2) or TLR receptor genes (TLR2, TLR4) were found. One case of primary MASP-2 deficiency was found among healthy pre-terms and one neonate suffering from SIRS was heterozygous for the rare FCN1 gene mutation, +6658 G>A. Generally, sepsis was associated with low serum MBL and low ficolin-2 concentrations on admission. Among neonates, ficolin-1 and MASP-2 levels were elevated in sepsis relative to healthy, but not disease, controls. Unlike neonates, ficolin-3 and MASP-2 levels were lower in older patients than in healthy controls while no difference was found for ficolin-1. With the possible exception of MBL, inherited lectin pathway insufficiencies do not seem to predispose to sepsis, rather changes in protein concentrations reflect alterations in disease course.

An Immunological Perspective on Neonatal Sepsis

Despite concerted international efforts, mortality from neonatal infections remains unacceptably high in some areas of the world, particularly for premature infants. Recent developments in flow cytometry and next-generation sequencing technologies have led to major discoveries over the past few years, providing a more integrated understanding of the developing human immune system in the context of its microbial environment. We review these recent findings, focusing on how in human newborns incomplete maturation of the immune system before a full term of gestation impacts on their vulnerability to infection. We also discuss some of the clinical implications of this research in guiding the design of more-accurate age-adapted diagnostic and preventive strategies for neonatal sepsis.

Attenuated innate immune defenses in very premature neonates during the neonatal period

BACKGROUND

Antimicrobial responses have been shown to be profoundly attenuated in very preterm neonates when examined on cord blood. However, we lack data on these responses at the time these neonates are most vulnerable to infections.

METHODS

Multiple cytokine responses to two prototypic Toll-like receptor (TLR) agonists: lipopolysaccharide (LPS) (TLR4) and R848 (TLR7/8) were prospectively measured in preterm neonates born ≤30 wk of gestation (n = 50) during the first 28 d of age using whole blood and single-cell multiparameter flow cytometry assays. Results were compared to term neonates (n = 30) and adult controls (n = 25).

RESULTS

In preterm neonates, LPS and R848 responses remained attenuated in both cord blood and in the first 28 d of age. These responses showed significant maturation over time after adjusting for gestational age and were confirmed in monocytes and dendritic cells on a per-cell basis. We detected no major contribution of chorioamnionitis, maternal antenatal corticosteroids or magnesium sulfate treatment, labor, or mode of delivery to the maturation of cytokine responses.

CONCLUSION

Innate immune antimicrobial defenses are profoundly attenuated developmentally in very preterm neonates during the neonatal period, suggesting that exogenous factors drive the sustained systemic inflammation that has been linked to increased morbidities in these infants.

The transient but not resident (TBNR) microbiome: a Yin Yang model for lung immune system

The concept of microbial content of the lung is still controversial. What make this more complicated are controversial results obtaining from different methodologies about lung microbiome and the definition of "lung sterility". Lungs may have very low bacteria but are not completely germ-free. Bacteria are constantly entering from the upper respiratory tract, but are then quickly being cleared. We can find bacterial DNA in the lungs, but it is much harder to ask about living bacteria. Here, we propose that if there is any trafficking of the microorganisms in the lung, it should be a "Transient But Not Resident (TBNR)" model. So, we speculate a "Yin Yang model" for the lung immune system and TBNR. Despite beneficial roles of microbiome on the development of lung immune system, any disruption and alteration in the microbiota composition of upper and lower airways may trigger or lead to several diseases such as asthma, chronic obstructive pulmonary disease and mustard lung disease.

Factors influencing gastrointestinal tract and microbiota immune interaction in preterm infants

The role of microbial colonization is indispensable for keeping a balanced immune response in life. However, the events that regulate the establishment of the microbiota, their timing, and the way in which they interact with the host are not yet fully understood. Factors such as gestational age, mode of delivery, environment, hygienic measures, and diet influence the establishment of microbiota in the perinatal period. Environmental microbes constitute the most important group of exogenous stimuli in this critical time frame. However, the settlement of a stable gut microbiota in preterm infants is delayed compared to term infants. Preterm infants have an immature gastrointestinal tract and immune system which predisposes to infectious morbidity. Neonatal microbial dynamics and alterations in early gut microbiota may precede and/or predispose to diseases such as necrotizing enterocolitis (NEC), late-onset sepsis or others. During this critical period, nutrition is the principal contributor for immunological and metabolic development, and microbiological programming. Breast milk is a known source of molecules that act synergistically to protect the gut barrier and enhance the maturation of the gut-related immune response. Host-microbe interactions in preterm infants and the protective role of diet focused on breast milk impact are beginning to be unveiled.

Underweight full-term Indian neonates show differences in umbilical cord blood leukocyte phenotype: a cross-sectional study

BACKGROUND

While infections are a major cause of neonatal mortality in India even in full-term neonates, this is an especial problem in the large proportion (~20%) of neonates born underweight (or small-for-gestational-age; SGA). One potential contributory factor for this susceptibility is the possibility that immune system maturation may be affected along with intrauterine growth retardation.

METHODS

In order to examine the possibility that differences in immune status may underlie the susceptibility of SGA neonates to infections, we enumerated the frequencies and concentrations of 22 leukocyte subset populations as well as IgM and IgA levels in umbilical cord blood from full-term SGA neonates and compared them with values from normal-weight (or appropriate-for-gestational-age; AGA) full-term neonates. We eliminated most SGA-associated risk factors in the exclusion criteria so as to ensure that AGA-SGA differences, if any, would be more likely to be associated with the underweight status itself.

RESULTS

An analysis of 502 such samples, including 50 from SGA neonates, showed that SGA neonates have significantly fewer plasmacytoid dendritic cells (pDCs), a higher myeloid DC (mDC) to pDC ratio, more natural killer (NK) cells, and higher IgM levels in cord blood in comparison with AGA neonates. Other differences were also observed such as tendencies to lower CD4:CD8 ratios and greater prominence of inflammatory monocytes, mDCs and neutrophils, but while some of them had substantial differences, they did not quite reach the standard level of statistical significance.

CONCLUSIONS

These differences in cellular lineages of the immune system possibly reflect stress responses in utero associated with growth restriction. Increased susceptibility to infections may thus be linked to complex immune system dysregulation rather than simply retarded immune system maturation.

Newborn physiological immaturity: a concept analysis

Background:

Most standardized nursing care plans for healthy neonates include multiple nursing diagnoses to reflect nurses' judgments on the infant's status; however scientific literature concerning this issue is scarce. Newborn physiological immaturity is a concept in the ATIC terminology (architecture, terminology, interface, information, nursing [infermeria], and knowledge [coneixement]) to represent the natural status of vulnerability of the healthy neonate.

Purpose:

To identify the essential attributes of the concept and provide its conceptual and operational definition, using the Wilsonian approach.

Findings:

The concept under analysis embeds a natural cluster of vulnerabilities and environmental interactions that enhance the evolving maturation process.

Implications for Practice:

The use of this diagnosis may simplify the process of charting the nursing care plans and reduce time needed for documentation while maintaining the integrity of the information.

Implications for Research:

Consistent development and use of nursing concepts is essential for knowledge building. Studies on the actual use of nursing diagnoses are needed to inform decision making.