The immune consequences of preterm birth

The effects of umblical cord clamping time on lymphocyte subgroups in term and late preterm infants

Aim

To evaluate the effect of umblical cord clamping time on lymphocyte subgroups in term and late preterm infants.

Material and Methods

Seventy-four infants between 34 and 41 weeks of gestation were included in the study. Of these, 37 were umbilical cord clamped immediately after birth and the remaining 37 were clamped after waiting one minute. Babies were divided into two groups as term and preterm. The prenatal, natal, postnatal characteristics of the infants were recorded. Hematologic and lymphocyte subgroups were investigated in cord blood and venous blood at day 7. Lymphocyte subgroups were evaluated using flow cytometry.

Results

With the delay of cord clamping, the leucocytes count and the percentage of CD3+T lymphocytes in cord blood of preterm infants decreased and this decrease continued at day 7. On the contrary, CD19+B lymphocyte levels in the cord blood of preterm infants increased, and this increase continued at day 7. Also, the percentage of CD4+T lymphocytes of preterm infants decreased with the delay of cord clamping at day 7. There was no difference between groups for the rate of sepsis development.

Conclusion

With the delay of cord clamping, the leucocytes count, the percentage of CD3+T, and CD4+T lymphocytes decreased, and the percentage of CD19+B lymphocytes increased in preterm infants. The delay in cord clamping time in term and preterm infants seems to have no impact on the rate of sepsis development. Larger series of studies are needed to assess the effect of these findings on the development of infection in late preterm infants who have delayed cord clamping.

Serratia marcescens outbreak in a neonatology unit of a Spanish tertiary hospital: Risk factors and control measures

BACKGROUND

We describe the investigation undertaken and the measures adopted to control a Serratia marcescens outbreak in the neonatology unit of La Paz University Hospital in Madrid, Spain.

METHODS

Weekly rectal and pharyngeal screenings for S marcescens were performed in the neonates starting after detection of the outbreak. Environmental samples and samples from health care workers (HCWs) were obtained for microbiological analysis. An unmatched case-control study was carried out to investigate risk factors for infection/colonization.

RESULTS

The outbreak began in June 2016 and ended in March 2017, affecting a total of 59 neonates. Twenty-five (42.37%) neonates sustained an infection, most frequently conjunctivitis and sepsis. Multivariate logistic regression identified the following risk factors: parenteral nutrition (odds ratio [OR], 103.4; 95% confidence interval [CI], 11.9-894.8), history of previous radiography (OR, 15.3; 95% CI, 2.4-95.6), and prematurity (OR, 5.65; 95% CI, 1.5-21.8). Various measures were adopted to control the outbreak, such as strict contact precautions, daily multidisciplinary team meetings, cohorting, allocation of dedicated staff, unit disinfection, and partial closure. Hands of HCWs were the main suspected mechanism of transmission, based on the inconclusive results of the environmental investigation and the high number of HCWs and procedures performed in the unit.

CONCLUSIONS

S marcescens spreads easily in neonatology units, mainly in neonatal intensive care units, and is often difficult to control, requiring a multidisciplinary approach. Strict measures, including cohorting and medical attention by exclusive staff, are often needed to get these outbreaks under control.

Establishment of an ideal gut microbiota to boost healthy growth of neonates

For decades, supporting the optimal growth of low birth weight (LBW) infants has been considered one of the most important paediatric challenges, despite advances in neonatal intensive care technology and nutrition interventions. Since gut microbiota affects such diverse phenotypes in adults, the difference in gut microbiota composition between normal infants and LBW infants raises the possibility of gut microbiota playing an important role in different growth rates of neonates. Based on the concept that probiotics are generally beneficial to the health, numerous studies have been made on probiotics as a supplement to the diet of the LBW infants. However, clinical results on the effects of probiotics on LBW infant growth are either inconsistent or contradictory with each other, and thus the contribution of gut microbiota in neonatal growth has remained inconclusive. In this review, recent researches on neonatal gut microbiota are discussed to develop a new strategy for targeting gut microbiota as a solution to growth retardation in LBW infants. We also discuss how to establish the ideal gut microbiota to support optimal growth of LBW infants.

Vascular Endothelium in Neonatal Sepsis: Basic Mechanisms and Translational Opportunities

Neonatal sepsis remains a major health issue worldwide, especially for low-birth weight and premature infants, with a high risk of death and devastating sequelae. Apart from antibiotics and supportive care, there is an unmet need for adjunctive treatments to improve the outcomes of neonatal sepsis. Strong and long-standing research on adult patients has shown that vascular endothelium is a key player in the pathophysiology of sepsis and sepsis-associated organ failure, through a direct interaction with pathogens, leukocytes, platelets, and the effect of soluble circulating mediators, in part produced by endothelial cells themselves. Despite abundant evidence that the neonatal immune response to sepsis is distinct from that of adults, comparable knowledge on neonatal vascular endothelium is much more limited. Neonatal endothelial cells express lower amounts of adhesion molecules compared to adult ones, and present a reduced capacity to neutralize reactive oxygen species. Conversely, available evidence on biomarkers of endothelial damage in neonates is not as robust as in adult patients, and endothelium-targeted therapeutic opportunities for neonatal sepsis are almost unexplored. Here, we summarize current knowledge on the structure of neonatal vascular endothelium, its interactions with neonatal immune system and possible endothelium-targeted diagnostic and therapeutic tools for neonatal sepsis. Furthermore, we outline areas of basic and translational research worthy of further study, to shed light on the role of vascular endothelium in the context of neonatal sepsis.

Necrotizing Enterocolitis and the Preterm Infant Microbiome

Bacterial colonization patterns in preterm infants differ from those of their term counterparts due to maternal microbial diversity, delivery mode, feeding methods, antibiotic use, and exposure to commensal microbiota and pathogens in the neonatal intensive care unit (NICU). Early gut microbiome dysbiosis predisposes neonates to necrotizing enterocolitis (NEC), a devastating intestinal disease with high morbidity and mortality. Though mechanisms of NEC pathogenesis are not fully understood, the microbiome is a promising therapy target for prevention and treatment. Direct administration of probiotics to preterm infants has been shown to reduce the incidence of NEC, but is not without risk. The immature immune systems of preterm infants leave them vulnerable to even beneficial bacteria. Further research is required to investigate both short-term and long-term effects of probiotic administration to preterm infants. Other methods of altering the preterm infant microbiome must also be considered, including breastfeeding, prebiotics, and targeting the maternal microbiome.

Gestational age and the long-term impact on children's infectious urinary morbidity

PURPOSE

Given the negative impact of prematurity on offspring's health, we sought to determine whether different gestational ages at birth impact differently on the prevalence of childhood infectious urinary morbidity in the offspring.

METHODS

In this population-based cohort analysis, all singleton deliveries occurring between 1991 and 2014 at a single regional tertiary medical center were included. Gestational age upon delivery was sub-divided into early preterm (< 34 weeks), late preterm (34-36 6/7 weeks), early term (37-38 6/7 weeks), full term (39-40 6/7 weeks), late term (41-41 6/7 weeks) and post-term (> 42 weeks). Congenital malformations were excluded. Rates of infectious urinary morbidity-related hospitalizations of offspring up to age 18 years were assessed using a survival curve and a Cox multivariable model.

RESULTS

During the study period, 238,620 deliveries met the inclusion criteria. Urinary-related hospitalization (n = 1395) rates decreased as gestational age increased, from 1.7% in the early preterm group, 0.9% in the late preterm group, 0.6% in the early-term group and only 0.5% in the full, late and post-term groups (p > 0.001; chi-square test for trends). In the Cox model, controlled for maternal age, preterm as well as early-term deliveries exhibited an independent association with pediatric urinary morbidity as compared with full term (early preterm: aHR-3.305, 95% CI 2.4-4.54; late preterm: aHR-1.63, 95% CI 1.33-1.99; early term: aHR-1.26, 95% CI 1.1-1.43, p = 0.01).

CONCLUSIONS

Deliveries occurring at preterm and at early term are independently associated with pediatric urinary morbidity in the offspring. This risk decreases as gestational age advances.

Colonization of preterm gnotobiotic piglets with probiotic Lactobacillus rhamnosus GG and its interference with Salmonella Typhimurium

A balanced microbiota of the gastrointestinal tract (GIT) is a prerequisite for a healthy host. The GIT microbiota in preterm infants is determined by the method of delivery and nutrition. Probiotics can improve the GIT microbiota balance and suitable animal models are required to verify their harmlessness. Preterm gnotobiotic piglets were colonized with Lactobacillus rhamnosus GG (LGG) to evaluate its safety and possible protective action against infection with an enteric pathogen, Salmonella Typhimurium (ST). Clinical signs (anorexia, somnolence, fever and diarrhea), bacterial interference and translocation, intestinal histopathology, transcriptions of claudin-1, occludin and interferon (IFN)-γ, intestinal and systemic protein levels of interleukin (IL)-8, IL-12/23 p40 and IFN-γ were compared among (i) germ-free, (ii) LGG-colonized, (iii) ST-infected and (iv) LGG-colonized and subsequently ST-infected piglets for 24 h. Both LGG and ST-colonized the GIT; LGG translocated in some cases into mesenteric lymph nodes and the spleen but did not cause bacteremia and clinical changes. ST caused clinical signs of gastroenteritis, translocated into mesenteric lymph nodes, the spleen, liver and blood, increased claudin-1 and IFN-γ transcriptions, but decreased occludin transcription and increased local and systemic levels of IL-8 and IL-12/23 p40. Previous colonization with LGG reduced ST colonization in the jejunum and translocation into the liver, spleen and blood. It partially ameliorated histopathological changes in the intestine, reduced IL-8 levels in the jejunum and plasma and IL-12/23 p40 in the jejunum. The preterm gnotobiotic piglet model of the vulnerable preterm immunocompromised infant is useful to verify the safety of probiotics and evaluate their protective effect.

Golden Hour Protocol for Preterm Infants: A Quality Improvement Project

BACKGROUND

Preterm infants are a vulnerable patient population, especially during the first hours of life. Hypothermia, hypoglycemia, and early-onset sepsis are common problems related to prematurity. Implementation of a Golden Hour protocol has been shown to improve outcomes for preterm infants.

PURPOSE

To evaluate the effectiveness of a Golden Hour protocol for infants born at less than 32 weeks' gestation on improving the admission process in a military care facility. Specific aims focused on temperature, time to initiation of intravenous (IV) fluids, time to administration of antibiotics, and time to close of the incubator top.

METHODS

A pre-/postdesign was used to compare outcomes from preimplementation to postimplementation. Predata were collected using electronic health record chart review and postdata were collected from the Neonatal Intensive Care Unit admission worksheet.

RESULTS

Although we did not find statistical significance, we found that more infants had a temperature greater than 36.5°C within 1 hour of birth and decrease in time to initiation of IV fluids and antibiotics from preimplementation to postimplementation, which is clinically significant. Time to close of the incubator top remained greater than 1 hour.

IMPLICATIONS FOR PRACTICE

Implementation of a Golden Hour protocol provides a guide to caring for preterm infants during the first hour of life to improve patient outcomes. Involvement of key stakeholders and staff education are key to successful implementation.

IMPLICATIONS FOR RESEARCH

Researchers should examine long-term outcomes related to implementation of a Golden Hour protocol in future studies. Future quality improvement projects should include the effectiveness of similar protocols and address possible barriers.

Associations of Neighborhood-Level Social Determinants of Health with Bacterial Infections in Young, Febrile Infants

OBJECTIVE

To examine the sociodemographic characteristics of one population of young, febrile infants and identify associations between neighborhood-level social determinants of health (SDHs) with bacterial infections.

STUDY DESIGN

This was a retrospective cross sectional study of all infants ≤90 days old with a temperature of ≥38°C who presented in 2014 to the emergency department of an urban children's hospital in a large east coast city. The primary outcome was the presence of a bacterial infection, defined as a positive urine, blood, or cerebrospinal fluid culture that was treated clinically as a pathogen. The home address of each infant was geocoded and linked to neighborhood data based on census tract. Neighborhood-level SDHs included deprivation index, median household income, poverty, childhood poverty, social capital, and crowded housing. Associations were estimated using generalized estimating equations and negative binomial regression analysis. Models were adjusted for age, prematurity, and race/ethnicity.

RESULTS

Of 232 febrile infants, the median age was 54 days, 58% were male, 49% were Hispanic, and 88% had public health insurance; 31 infants (13.4%) had a bacterial infection. In the adjusted analyses, the risk of bacterial infection among infants from neighborhoods with high rates of childhood poverty was >3 times higher (relative risk, 3.16; 95% CI, 1.04-9.6) compared with infants from neighborhoods with low rates of childhood poverty.

CONCLUSIONS

Our findings suggest that SDHs may be associated with bacterial infections in young, febrile infants. If confirmed in subsequent studies, the inclusion of SDHs in predictive tools may improve accuracy in detecting bacterial infections among young, febrile infants.

Neonatal gut and immune maturation is determined more by postnatal age than by postconceptional age in moderately preterm pigs

Preterm infants have immature organ functions that predispose them to gut and immune disorders. Developmental delays at preterm birth may affect various organs differently at term-corrected age. We hypothesized that gut and immune maturation in moderately preterm neonates depends more on birth and postnatal factors than on advancing postconceptional age (PCA). Using preterm pigs as models, we investigated how gut and immune parameters develop until term-corrected age and how these differ from those in term counterparts. Preterm ( n = 43, 106 days of gestation) and term pigs ( n = 41, 116 days of gestation) were delivered by caesarean section and euthanized at birth ( day 1) or postnatal day 11 (term-corrected age for preterm pigs) using identical rearing conditions. Relative to term pigs, preterm pigs had lower blood oxygenation, glucose, and cortisol levels, lower gut lactase activity, villus height, and goblet cell density, and lower blood neutrophil, helper T, and cytotoxic T cell numbers at birth. Despite slower growth in preterm pigs, most intestinal and immune parameters increased markedly after birth in both groups. However, some parameters remained negatively affected by preterm birth until postnatal day 11 (goblet cells, gut permeability, and cytotoxic T cells). The colon microbiota showed limited differences between preterm and term pigs at this time. At the same PCA, preterm 11-day-old pigs had higher blood leukocyte numbers and gut enzyme activities but lower villus height and blood cytotoxic T cell numbers relative to newborn term pigs. Birth and postnatal factors, not advancing PCA, are key determinants of gut and immune maturation in moderately preterm neonates. NEW & NOTEWORTHY Postnatally, preterm infants are often considered to reach a physiological maturation similar to that in term infants when they reach term-corrected postconceptional age (PCA). Using preterm pigs as models, we show that PCA may be a poor measure of gut and immune maturation because environmental triggers (regardless of PCA at birth) are critical. Possibly, PCA is only relevant to evaluate physiological maturation of organs that develop relatively independent of the external environment (e.g., the brain).

Early Life Incidence of Gastrointestinal and Respiratory Infections in Children With Gastroschisis: A Cohort Study

OBJECTIVES

Survival in infants with gastroschisis is increasing although little is known about early childhood morbidity. In the context of a hypothesized link between the gastrointestinal (GI) tract and immune function, this study explores rates of GI and respiratory infections in children with gastroschisis.

METHODS

We conducted a population-based retrospective cohort study using data from the Health Improvement Network, a large database of UK primary care medical records. We identified children born from 1990 to 2013, and extracted follow-up data to their fifth birthday. We calculate incidence rates (IR) of GI and respiratory tract infections, overall and stratified by age, sex, socioeconomic status, and gestational age at birth, and compared these between children with and without gastroschisis by calculating adjusted incidence rate ratios (aIRR).

RESULTS

Children with gastroschisis had a 65% higher IR of GI infection compared to children without (aIRR 1.65, 95% confidence interval [CI] 1.37-1.99, P < 0.001). Children with gastroschisis had a 27% higher IR of all respiratory tract infections (aIRR 1.27, 95% CI 1.12-1.44, P < 0.001) and more than 2-fold increase in lower respiratory tract infections compared to children without the condition (aIRR 2.15, 95% CI 1.69-2.74, P < 0.001).

CONCLUSIONS

Children born with gastroschisis have a significantly higher incidence of GI and respiratory tract infections compared to children without gastroschisis. This association requires further investigations but could be related to the neonatal care they receive such as delayed enteral feeding or frequent antibiotic courses altering the gut microbiome and developing immune system.

Persistent and progressive long-term lung disease in survivors of preterm birth

Preterm birth accounts for approximately 11% of births globally, with rates increasing across many countries. Concurrent advances in neonatal care have led to increased survival of infants of lower gestational age (GA). However, infants born <32 weeks of GA experience adverse respiratory outcomes, manifesting with increased respiratory symptoms, hospitalisation and health care utilisation into early childhood. The development of bronchopulmonary dysplasia (BPD) - the chronic lung disease of prematurity - further increases the risk of poor respiratory outcomes throughout childhood, into adolescence and adulthood. Indeed, survivors of preterm birth have shown increased respiratory symptoms, altered lung structure, persistent and even declining lung function throughout childhood. The mechanisms behind this persistent and sometimes progressive lung disease are unclear, and the implications place those born preterm at increased risk of respiratory morbidity into adulthood. This review aims to summarise what is known about the long-term pulmonary outcomes of contemporary preterm birth, examine the possible mechanisms of long-term respiratory morbidity in those born preterm and discuss addressing the unknowns and potentials for targeted treatments.

The impact of respiratory viruses on lung health after preterm birth

Children born preterm, less than 37 weeks' gestation, are at increased risk of viral respiratory infections and associated complications both during their initial birth hospitalisation and in their first years following discharge. This increased burden of viral respiratory infections is likely to have long term implications for lung health and function in individuals born preterm, particularly those with bronchopulmonary dysplasia. Several hypotheses have been put forward to explain the association between early life viral respiratory infection and development of suboptimal lung health and function later in life following preterm birth. Although preterm infants with diminished lung function, particularly small airways, might be particularly susceptible to asthma and wheezing disorders following viral infection, there is evidence that respiratory viruses can activate number of inflammatory and airway re-modelling pathways. Therefore, the aim of this review is to highlight the perinatal and early life risk factors that may contribute to increased susceptibility to viral respiratory infections among preterm infants during early life and to understand how respiratory viral infection may influence the development of abnormal lung health and function later in life.

Epigenetic signature of preterm birth in adult twins

Background

Preterm birth is a leading cause of perinatal mortality and long-term health consequences. Epigenetic mechanisms may have been at play in preterm birth survivors, and these could be persistent and detrimental to health later in life.

Methods

We performed a genome-wide DNA methylation profiling in adult twins of premature birth to identify genomic regions under differential epigenetic regulation in 144 twins with a median age of 33 years (age range 30-36).

Results

Association analysis detected three genomic regions annotated to the SDHAP3, TAGLN3 and GSTT1 genes on chromosomes 5, 3 and 22 (FWER: 0.01, 0.02 and 0.04) respectively. These genes display strong involvement in neurodevelopmental disorders, cancer susceptibility and premature delivery. The three identified significant regions were successfully replicated in an independent sample of twins of even older age (median age 66, range 56-80) with similar regulatory patterns and nominal p values < 5.05e-04. Biological pathway analysis detected five significantly enriched pathways all explicitly involved in immune responses.

Conclusion

We have found novel evidence associating premature delivery with epigenetic modification of important genes/pathways and revealed that preterm birth, as an early life event, could be related to differential methylation regulation patterns observable in adults and even at high ages which could potentially mediate susceptibility to age-related diseases and adult health.

Air pollutants and early origins of respiratory diseases

Air pollution is a global health threat and causes millions of human deaths annually. The late onset of respiratory diseases in children and adults due to prenatal or perinatal exposure to air pollutants is emerging as a critical concern in human health. Pregnancy and fetal development stages are highly susceptible to environmental exposure and tend to develop a long-term impact in later life. In this review, we briefly glance at the direct impact of outdoor and indoor air pollutants on lung diseases and pregnancy disorders. We further focus on lung complications in later life with early exposure to air pollutants. Epidemiological evidence is provided to show the association of prenatal or perinatal exposure to air pollutants with various adverse birth outcomes, such as preterm birth, lower birth weight, and lung developmental defects, which further associate with respiratory diseases and reduced lung function in children and adults. Mechanistic evidence is also discussed to support that air pollutants impact various cellular and molecular targets at early life, which link to the pathogenesis and altered immune responses related to abnormal respiratory functions and lung diseases in later life.

Examining Early Childhood Health Outcomes of Children Born Late Preterm in Urban Manitoba

Objective The late preterm population [34-36 weeks gestational age (GA)] is known to incur increased morbidity in the infancy stage compared to the population born at term (39-41 weeks GA). This study aimed to examine the health of these children during their early childhood years, with specific attention to the role of socioeconomic status. Methods A retrospective cohort study was conducted using data from the Manitoba Centre for Health Policy, including all live-born children born at 34-36 and 39-41 weeks GA in urban Manitoba between 2000 and 2005 (n = 28,100). Multivariable logistic regression was used to examine the association of GA with early childhood morbidity after controlling for maternal, child and family level variables. Results The late preterm population was found to have significantly greater adjusted odds of lower respiratory tract infections in the preschool years (aOR = 1.59 [1.24, 2.04]) and asthma at school age (aOR = 1.33 [1.18, 1.47]) compared to the population born at term. The groups also differed in health care utilization at ages 4 (aOR = 1.19 [1.06,1.34]) and 7 years (aOR = 1.24 [1.09, 1.42]). Additional variables associated with poor outcomes suggest that social deprivation and GA simultaneously have a negative impact on early childhood development. Conclusions for Practice Adjustment for predictors of poor early childhood development, including socioeconomic status, were found to attenuate but not eliminate health differences between children born late preterm and children born at term. Poorer health outcomes that extend into childhood have implications for practice at the population level and suggest a need for further follow-up post discharge.

Immune function? A missing link in the gender disparity in preterm neonatal outcomes

INTRODUCTION

In neonatology, males exhibit a more severe disease course and poorer prognosis in many pathological states when compared to females. Perinatal brain injury, respiratory morbidity, and sepsis, among other complications, preferentially affect males. Preterm neonates (born <37 weeks gestation) display a particularly marked sexual disparity in pathology, especially at the borders of viability. The sex biases in preterm neonatal outcomes and underlying multifactorial mechanisms have been incompletely explored. Sex-specific clinical phenomena may be partially explained by intrinsic differences in immune function. The distinct immune system of preterm neonates renders this patient population vulnerable, and it is increasingly important to consider biological sex in disease processes and to strive for improved outcomes for both sexes. Areas covered: We discuss the cellular responses and molecular intermediates in immune function which are strongly dependent on sex-specific factors such as the genetic and hormonal milieu of premature birth and consider novel findings in a clinical context. Expert commentary: The role of immune function in the manifestation of sex-specific disease manifestations and outcomes in preterm neonates is a critical prognostic variable. Further mechanistic elucidation will yield valuable translational and clinical information of disease processes in preterm neonates which may be harnessed for modulation.

A Critical Review of the Bacterial Baptism Hypothesis and the Impact of Cesarean Delivery on the Infant Microbiome

Numerous studies suggest that infants delivered by cesarean section are at a greater risk of non-communicable diseases than their vaginal counterparts. In particular, epidemiological studies have linked Cesarean delivery with increased rates of asthma, allergies, autoimmune disorders, and obesity. Mode of delivery has also been associated with differences in the infant microbiome. It has been suggested that these differences are attributable to the "bacterial baptism" of vaginal birth, which is bypassed in cesarean deliveries, and that the abnormal establishment of the early-life microbiome is the mediator of later-life adverse outcomes observed in cesarean delivered infants. This has led to the increasingly popular practice of "vaginal seeding": the iatrogenic transfer of vaginal microbiota to the neonate to promote establishment of a "normal" infant microbiome. In this review, we summarize and critically appraise the current evidence for a causal association between Cesarean delivery and neonatal dysbiosis. We suggest that, while Cesarean delivery is certainly associated with alterations in the infant microbiome, the lack of exposure to vaginal microbiota is unlikely to be a major contributing factor. Instead, it is likely that indication for Cesarean delivery, intrapartum antibiotic administration, absence of labor, differences in breastfeeding behaviors, maternal obesity, and gestational age are major drivers of the Cesarean delivery microbial phenotype. We, therefore, call into question the rationale for "vaginal seeding" and support calls for the halting of this practice until robust evidence of need, efficacy, and safety is available.

Immunization practices in low birth weight infants from rural Haryana, India: Findings from secondary data analysis

Background

Low birth weight (LBW) infants constitute a vulnerable subset of infants with impaired immunity in early life. In India, there is scarcity of studies that focus on immunization practices in such infants. This analysis aimed to examine immunization practices in LBW infants with the intention to identify areas requiring intervention.

Methods

Data on immunization status of LBW infants enrolled in an individually randomized, double–masked, placebo–controlled trial of neonatal vitamin A supplementation were analysed. Study outcomes were full immunization by one year of age and delayed vaccination with DPT1 and DPT3. Multivariable logistic regression was performed to identify factors associated with the outcome(s).

Findings

Out of 10 644 LBW infants enrolled in trial, immunization data were available for 10 517 (98.8%). Less than one–third (29.7%) were fully immunized by one year of age. Lowest wealth quintile (adjusted odds ratio (AOR) 0.39, 95% confidence interval (CI) 0.32–0.47), Muslim religion (AOR 0.41, 95% CI 0.35–0.48) and age of mother <20 years (AOR 0.62, 95% CI 0.52–0.73) were associated with decreased odds of full immunization. Proportion of infants with delayed vaccination for DPT1 and DPT3 were 52% and 81% respectively. Lowest wealth quintiles (AOR 1.51, 95% CI 1.25–1.82), Muslim religion (AOR 1.41, 95% CI 1.21–1.65), mother aged <20 years (AOR 1.31, 95% CI 1.11–1.53) and birth weight <2000 g (AOR 1.20, 95% CI 1.03–1.40) were associated with higher odds of delayed vaccination for DPT–1. Maternal education (≥12 years of schooling) was associated with high odds of full immunization (AOR 2.39, 95% CI 1.97–2.91) and low odds of delayed vaccination for both DPT–1 (AOR 0.59, 95% CI 0.49–0.73) and DPT–3 (AOR 0.57, 95% CI 0.43–0.76)

Conclusion

In this population, LBW infants are at a risk of delayed and incomplete immunization and therefore need attention. The risks are even higher in identified subgroups that should specifically be targeted

Neonatal intestinal dysbiosis in necrotizing enterocolitis

Necrotizing Enterocolitis (NEC) is one of the most devastating gastrointestinal diseases in neonates, particularly among preterm infants in whom surgical NEC is the leading cause of morbidity. NEC pathophysiology occurs in the hyper-reactive milieu of the premature gut after bacterial colonization. The resultant activation of the TLR4 pathway appears to be a strongly contributing factor. Advancements in metagenomics may yield new clarity to the relationship between the neonatal intestinal microbiome and the development of NEC. After a century without effective directed treatments, microbiome manipulation offers a promising therapeutic target for the prevention and treatment of this devastating disease.

Immunization of preterm infants with GSK's hexavalent combined diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus-Haemophilus influenzae type b conjugate vaccine: A review of safety and immunogenicity

BACKGROUND

Infants with history of prematurity (<37 weeks gestation) and low birth weight (LBW, <2500 g) are at high risk of infection due to functional immaturity of normal physical and immunological defense mechanisms. Despite current recommendations that infants with history of prematurity/LBW should receive routine immunization according to the same schedule and chronological age as full-term infants, immunization is often delayed.

METHODS

Here we summarize 10 clinical studies and 15 years of post-marketing safety surveillance of GSK's hexavalent vaccine (DTPa-HBV-IPV/Hib), a combined diphtheria-tetanus-acellular-pertussis-hepatitis-B-inactivated-poliovirus-Haemophilus influenzae-type-b (Hib) conjugate vaccine, when administered alone, or co-administered with pneumococcal conjugate, rotavirus, and meningococcal vaccines and respiratory syncytial virus IgG to infants with history of prematurity/LBW in clinical trials.

RESULTS

At least 92.5% of infants with history of prematurity/LBW as young as 24 weeks gestation in clinical studies were seropositive to all vaccine antigens after 3-dose primary vaccination with GSK's hexavalent DTPa-HBV-IPV/Hib vaccine, with robust immune responses to booster vaccination. Seropositivity rates and antibody concentrations to hepatitis B and Hib appeared lower in infants with history of prematurity/LBW than term infants. Between 13-30% of medically stable infants with history of prematurity developed apnea after vaccination with GSK's hexavalent DTPa-HBV-IPV/Hib vaccine; usually after dose 1. The occurrence of post-immunization cardiorespiratory events appears to be influenced by the severity of any underlying neonatal condition. Most cardiorespiratory events resolve spontaneously or require minimal intervention. GSK's hexavalent DTPa-HBV-IPV/Hib vaccine was well tolerated in co-administration regimens.

CONCLUSION

GSK's hexavalent DTPa-HBV-IPV/Hib vaccine alone or co-administered with other pediatric vaccines has a clinically acceptable safety and immunogenicity profile when used in infants with history of prematurity/LBW for primary and booster vaccination. Additional studies are needed in very premature and very LBW infants. However, currently available data support using GSK's hexavalent DTPa-HBV-IPV/Hib vaccine to immunize infants with history of prematurity/LBW according to chronological age.

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.

Clinical definition of respiratory viral infections in young children and potential bronchiolitis misclassification

Viral respiratory infections are often grouped as a single respiratory syndrome named 'viral bronchiolitis', independently of the viral etiology or individual risk factors. Clinical trials and guidelines have used a more stringent definition of viral bronchiolitis, including only the first episode of wheezing in children less than 12 months of age without concomitant respiratory comorbidities. There is increasing evidence suggesting that this definition is not being followed by pediatric care providers, but it is unclear to what extent viral respiratory infections are currently misclassified as viral bronchiolitis using standard definitions. We conducted a retrospective analysis of hospitalized young children (≤3 years) due to viral respiratory infections. Bronchiolitis was defined as the first wheezing episode less than 12 months of age. Demographic variables and comorbidities were obtained by electronic medical record review. The study comprised a total of 513 hospitalizations (n=453). Viral bronchiolitis was diagnosed in 144 admissions (28.1%). Notably, we identified that the majority of children diagnosed with bronchiolitis (63%) were misclassified as they had prior episodes of wheezing. Many children with bronchiolitis misclassification had significant comorbidities, including prematurity (51%), neuromuscular conditions (9.8%), and congenital heart disease (9.8%). Misclassification of bronchiolitis is a common problem that may lead to inappropriate management of viral respiratory infections in young children. A comprehensive approach that takes into consideration viral etiology and individual risk factors may lead to a more accurate clinical assessment of this condition and would potentially prevent bronchiolitis misclassification.

Glial cell responses in a murine multifactorial perinatal brain injury model

The impact of traumatic brain injury during the perinatal period, which coincides with glial cell (astrocyte and oligodendrocyte) maturation was assessed to determine whether a second insult, e.g., increased inflammation due to remote bacterial exposure, exacerbates the initial injury's effects, possibly eliciting longer-term brain damage. Thus, a murine multifactorial injury model incorporating both mechanisms consisting of perinatal penetrating traumatic brain injury, with or without intraperitoneal injection of lipopolysaccharide (LPS), an analog of remote pathogen exposure has been developed. Four days after injury, gene expression changes for different cell markers were assessed using mRNA in situ hybridization (ISH) and qPCR. Astrocytic marker mRNA levels increased in the stab-alone and stab-plus-LPS treated animals indicating reactive gliosis. Activated microglial/macrophage marker levels, increased in the ipsilateral sides of stab and stab-plus LPS animals by P10, but the differences resolved by P15. Ectopic expression of glial precursor and neural stem cell markers within the cortical injury site was observed by ISH, suggesting that existing precursors and neural stem cells migrate into the injured areas to replace the cells lost in the injury process. Furthermore, single exposure to LPS concomitant with acute stab injury affected the oligodendrocyte population in both the injured and contralateral uninjured side, indicating that after compromise of the blood-brain barrier integrity, oligodendrocytes become even more susceptible to inflammatory injury. This multifactorial approach should lead to a better understanding of the pathogenic sequelae observed as a consequence of perinatal brain insult/injury, caused by combinations of trauma, intrauterine infection, hypoxia and/or ischemia in humans.

Public Clonotypes and Convergent Recombination Characterize the Naïve CD8+ T-Cell Receptor Repertoire of Extremely Preterm Neonates

Respiratory support improvements have aided survival of premature neonates, but infection susceptibility remains a predominant problem. We previously reported that neonatal mice have a rapidly evolving T-cell receptor (TCR) repertoire that impairs CD8⁺ T cell immunity. To understand the impact of prematurity on the human CD8⁺ TCR repertoire, we performed next-generation sequencing of the complementarity-determining region 3 (CDR3) from the rearranged TCR variable beta (Vβ) in sorted, naïve CD8⁺ T cells from extremely preterm neonates (23–27 weeks gestation), term neonates (37–41 weeks gestation), children (16–56 months), and adults (25–50 years old). Strikingly, preterm neonates had an increased frequency of public clonotypes shared between unrelated individuals. Public clonotypes identified in preterm infants were encoded by germline gene sequences, and some of these clonotypes persisted into adulthood. The preterm neonatal naïve CD8⁺ TCR repertoire exhibited convergent recombination, characterized by different nucleotide sequences encoding the same amino acid CDR3 sequence. As determined by Pielou’s evenness and iChao1 metrics, extremely preterm neonates have less clonality, and a much lower bound for the number of unique TCR within an individual preterm neonate, which indicates a less rich and diverse repertoire, as compared to term neonates, children, and adults. This suggests that T cell selection in the preterm neonate may be less stringent or different. Our analysis is the first to compare the TCR repertoire of naïve CD8⁺ T cells between viable preterm neonates and term neonates. We find preterm neonates have a repertoire immaturity which potentially contributes to their increased infection susceptibility. A developmentally regulated, evenly distributed repertoire in preterm neonates may lead to the inclusion of public TCR CDR3β sequences that overlap between unrelated individuals in the preterm repertoire.

Optimisation of 16S rRNA gut microbiota profiling of extremely low birth weight infants

BACKGROUND

Infants born prematurely, particularly extremely low birth weight infants (ELBW) have altered gut microbial communities. Factors such as maternal health, gut immaturity, delivery mode, and antibiotic treatments are associated with microbiota disturbances, and are linked to an increased risk of certain diseases such as necrotising enterocolitis. Therefore, there is a requirement to optimally characterise microbial profiles in this at-risk cohort, via standardisation of methods, particularly for studying the influence of microbiota therapies (e.g. probiotic supplementation) on community profiles and health outcomes. Profiling of faecal samples using the 16S rRNA gene is a cost-efficient method for large-scale clinical studies to gain insights into the gut microbiota and additionally allows characterisation of cohorts were sample quantities are compromised (e.g. ELBW infants). However, DNA extraction method, and the 16S rRNA region targeted can significantly change bacterial community profiles obtained, and so confound comparisons between studies. Thus, we sought to optimise a 16S rRNA profiling protocol to allow standardisation for studying ELBW infant faecal samples, with or without probiotic supplementation.

METHODS

Using ELBW faecal samples, we compared three different DNA extraction methods, and subsequently PCR amplified and sequenced three hypervariable regions of the 16S rRNA gene (V1 + V2 + V3), (V4 + V5) and (V6 + V7 + V8), and compared two bioinformatics approaches to analyse results (OTU and paired end). Paired shotgun metagenomics was used as a 'gold-standard'.

RESULTS

Results indicated a longer bead-beating step was required for optimal bacterial DNA extraction and that sequencing regions (V1 + V2 + V3) and (V6 + V7 + V8) provided the most representative taxonomic profiles, which was confirmed via shotgun analysis. Samples sequenced using the (V4 + V5) region were found to be underrepresented in specific taxa including Bifidobacterium, and had altered diversity profiles. Both bioinformatics 16S rRNA pipelines used in this study (OTU and paired end) presented similar taxonomic profiles at genus level.

CONCLUSIONS

We determined that DNA extraction from ELBW faecal samples, particularly those infants receiving probiotic supplementation, should include a prolonged beat-beating step. Furthermore, use of the 16S rRNA (V1 + V2 + V3) and (V6 + V7 + V8) regions provides reliable representation of ELBW microbiota profiles, while inclusion of the (V4 + V5) region may not be appropriate for studies where Bifidobacterium constitutes a resident microbiota member.

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.

Quality Improvement Project to Reduce Delayed Vaccinations in Preterm Infants

BACKGROUND

Preterm infants are especially vulnerable to infectious diseases. Although vaccinations are a safe and effective measure to protect preterm infants from vaccine-preventable diseases, delays in vaccinations are not uncommon.

PURPOSE

The goal of this quality improvement project was to improve on time vaccinations of preterm infants hospitalized in the neonatal intensive care unit.

METHODS

The Plan-Do-Study-Act model of quality improvement was adopted to develop, test, and implement interventions aimed at improving timely vaccination of preterm infants. The primary outcome measure of interest was the rate of on time vaccination, which was defined as the proportion of medically eligible preterm infants who received vaccinations within 2 weeks of the recommended schedule.

RESULTS

Baseline on time vaccination rate was only 36%. Following several Plan-Do-Study-Act cycles, a steady increase in on time vaccinations of eligible infants was observed, and a new baseline on time vaccination rate of 82% was achieved.

IMPLICATIONS FOR PRACTICE

Simple interventions implemented within the context of Plan-Do-Study-Act cycles are effective in improving timely vaccinations among preterm infants.

IMPLICATIONS FOR RESEARCH

Future research that focuses on vaccinations in preterm infants is needed to further reinforce the safety and efficacy of vaccines. Effective methods on how to disseminate and apply this knowledge to practice should also be studied.Video Abstract available at http://links.lww.com/ANC/A27.

Outcomes and risk factors of ventilator-associated pneumonia in neonates

BACKGROUND

Ventilator-associated pneumonia (VAP) in neonates has been associated with high mortality and poor outcome. This study aimed to compare the incidence, risk factors, and outcomes of VAP and non- VAP conditions in neonates.

METHODS

We performed a prospective cohort study in a neonatal intensive care unit (NICU) in Thailand from January 2014 to December 2014. All neonatal patients who were ventilated more than 48 hours were enrolled.

RESULTS

There were 128 enrolled patients. The median (inter quartile range) gestational age and birthweight were 35 (30.2, 37.8) weeks and 2380 (1323.8, 3020.0) g. There were 17 VAP patients (19 episodes) and 111 non-VAP ones. The VAP rate was 13.3% or 10.1 per 1000 ventilator days. According to the multivariate analysis, a birthweight less than 750 g [adjusted odds ratio (aOR)=10.75, 95% confidence interval (CI)=2.35-49.16; P=0.002] and sedative medication use (aOR=4.00, 95% CI=1.23-12.50; P=0.021) were independent risk factors for VAP. Compared with the non-VAP group, the median difference in the VAP group yielded a significantly longer duration of NICU stay (18 days, P=0.001), total length of hospital stay (16 days, P=0.002) and higher hospital costs ($5113, P=0.001). The inhospital mortality rate in the VAP and non-VAP groups was 17.6% and 15.3% (P=0.73), respectively.

CONCLUSIONS

A neonatal birthweight less than 750 g and sedative medication use were independent risk factors for VAP. Our VAP patients experienced a longer duration of both NICU and hospital stay, and incurred higher hospitalization costs.

Genome-resolved metaproteomic characterization of preterm infant gut microbiota development reveals species-specific metabolic shifts and variabilities during early life

BACKGROUND

Establishment of the human gut microbiota begins at birth. This early-life microbiota development can impact host physiology during infancy and even across an entire life span. However, the functional stability and population structure of the gut microbiota during initial colonization remain poorly understood. Metaproteomics is an emerging technology for the large-scale characterization of metabolic functions in complex microbial communities (gut microbiota).

RESULTS

We applied a metagenome-informed metaproteomic approach to study the temporal and inter-individual differences of metabolic functions during microbial colonization of preterm human infants' gut. By analyzing 30 individual fecal samples, we identified up to 12,568 protein groups for each of four infants, including both human and microbial proteins. With genome-resolved matched metagenomics, proteins were confidently identified at the species/strain level. The maximum percentage of the proteome detected for the abundant organisms was ~45%. A time-dependent increase in the relative abundance of microbial versus human proteins suggested increasing microbial colonization during the first few weeks of early life. We observed remarkable variations and temporal shifts in the relative protein abundances of each organism in these preterm gut communities. Given the dissimilarity of the communities, only 81 microbial EggNOG orthologous groups and 57 human proteins were observed across all samples. These conserved microbial proteins were involved in carbohydrate, energy, amino acid and nucleotide metabolism while conserved human proteins were related to immune response and mucosal maturation. We identified seven proteome clusters for the communities and showed infant gut proteome profiles were unstable across time and not individual-specific. Applying a gut-specific metabolic module (GMM) analysis, we found that gut communities varied primarily in the contribution of nutrient (carbohydrates, lipids, and amino acids) utilization and short-chain fatty acid production.

CONCLUSIONS

Overall, this study reports species-specific proteome profiles and metabolic functions of human gut microbiota during early colonization. In particular, our work contributes to reveal microbiota-associated shifts and variations in the metabolism of three major nutrient sources and short-chain fatty acid during colonization of preterm infant gut.

Pulmonary vascular changes in extremely preterm sheep after intra-amniotic exposure to Ureaplasma parvum and lipopolysaccharide

Background

Chorioamnionitis can induce pulmonary inflammation and promote bronchopulmonary dysplasia development, distinguished by alveolar simplification and impaired vascular growth. Chorioamnionitis is more common during the extremely preterm canalicular lung stage (crucial for vascular development); and increases the risk for subsequent sepsis. We hypothesized that single/combined exposure to chronic and/or acute inflammation induces pulmonary inflammatory responses and vascular changes.

Methods

Ovine fetuses were intra-amniotically exposed to chronic Ureaplasma parvum (UP) at 24 days (d) before extreme preterm delivery at 94d (term 147d) and/or to lipopolysaccharide (LPS) 7 or 2d before delivery. Pulmonary inflammation, vascular remodeling and angiogenic factors were assessed.

Results

LPS exposure increased CD3-positive and myeloperoxidase-positive cells. Combined UP-LPS exposure increased pulmonary inflammation compared with 2d LPS or UP groups. The UP+2d LPS group had an increased adventitial fibrosis score when compared with UP-treated animals. A reduced wall-to-lumen ratio was found in the 7d LPS animals when compared to the 2d LPS-treated animals. Exposure to UP+2d LPS reduced VEGF and VEGFR-2 levels compared with 2d LPS-treated animals. Angiopoietin-1 (Ang1) and tunica interna endothelial cell kinase 2 (Tie-2) levels were decreased after UP+7d LPS as well as after 7d LPS, but not with UP alone.

Conclusion

Chronic UP and subsequent LPS exposure increased pulmonary inflammation and decreased expression of angiogenic growth factors and receptors when compared to single hit-exposed animals.

Intrauterine infection, immune system and premature birth

Preterm birth accounts for nearly one million deaths among children under five years of age, and although its etiopathogenesis is not fully elucidated, ascending intrauterine infection and fetal inflammatory response seem to be the main triggers. The intense inflammatory response mediated by IL-1β, TNF-α, PAF, IFN-γ and IL-6, PGE₂ and MMP-1 and MMP-9 causes fetal membrane damage and rupture, increased uterine contractions and biochemical and structural changes in the cervix. Furthermore, preterm neonates have deficient innate and adaptive immune responses characterized by reduced levels of IgG, opsonization and phagocytosis, as well as increased activation of Th1 cells in relation to Th2 cells. Therefore, this triad is favors the occurrence of neonatal complications, such as respiratory distress syndrome, necrotizing enterocolitis, retinopathy of prematurity and bronchopulmonary dysplasia. Due to serious maternal and child health complications of intrauterine infection, several studies have tried to identify biomarkers for the early diagnosis of this entity. This literature review aims to discuss the main scientific findings regarding the association between ascending intrauterine infection, immune system and preterm birth.

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.

Livebearing or egg-laying mammals: 27 decisive nucleotides of FAM168

In the present study, we determine comprehensive molecular phylogenetic relationships of the novel myelin-associated neurite-outgrowth inhibitor (MANI) gene across the entire eukaryotic lineage. Combined computational genomic and proteomic sequence analyses revealed MANI as one of the two members of the novel family with sequence similarity 168 member (FAM168) genes, consisting of FAM168A and FAM168B, having distinct genetic differences that illustrate diversification in its biological function and genetic taxonomy across the phylogenetic tree. Phylogenetic analyses based on coding sequences of these FAM168 genes revealed that they are paralogs and that the earliest emergence of these genes occurred in jawed vertebrates such as Callorhinchus milii. Surprisingly, these two genes are absent in other chordates that have a notochord at some stage in their lives, such as branchiostoma and tunicates. In the context of phylogenetic relationships among eukaryotic species, our results demonstrate the presence of FAM168 orthologs in vertebrates ranging from Callorhinchus milii to Homo sapiens, displaying distinct taxonomic clusters, comprised of fish, amphibians, reptiles, birds, and mammals. Analyses of individual FAM168 exons in our sample provide new insights into the molecular relationships between FAM168A and FAM168B (MANI) on the one hand and livebearing and egg-laying mammals on the other hand, demonstrating that a distinctive intermediate exon 4, comprised of 27 nucleotides, appears suddenly only in FAM168A and there in the livebearing mammals only but is absent from all other species including the egg-laying mammals.

Palivizumab Exposure and the Risk of Atopic Dermatitis, Asthma and Allergic Rhinoconjunctivitis: A Cross-National, Population-Based Cohort Study

BACKGROUND

Palivizumab is a humanized monoclonal antibody designed to provide passive immunity against respiratory syncytial virus. It is prescribed to children at high risk for severe infection with respiratory syncytial virus. However, little is known about the risk of the immune-mediated diseases atopic dermatitis, asthma, and allergic rhinoconjunctivitis after palivizumab exposure.

AIM

Our objective was to investigate whether exposure to palivizumab was associated with atopic dermatitis, asthma, or allergic rhinoconjunctivitis in childhood.

METHODS

This was a cross-national population-based cohort study including data from 769,523 Danish children born 1 January 1999-31 December 2010 and 581,742 Swedish children born 1 July 2005-31 December 2010. Since palivizumab is only indicated for children at the highest risk, sub-cohorts of preterm children, children with bronchopulmonary dysplasia, and children with hemodynamic significant heart disease were defined.

RESULTS

Of the 1,351,265 children included, 1192 (0.09%) were exposed to palivizumab. An increased risk of asthma after palivizumab exposure was observed in the total birth cohort (hazard ratio [HR] 1.49; 95% confidence interval [CI] 1.32-1.68) and in the sub-cohort of preterm children (HR 1.24; 95% CI 1.07-1.44). However, post hoc analyses using the propensity score to balance confounding factors found no increased risk of asthma in preterm children (HR 0.91; 95% CI 0.56-1.48). No increased risks of atopic dermatitis (HR 1.18; 95% CI 0.94-1.48) or allergic rhinoconjunctivitis (HR 1.14; 95% CI 0.92-1.42) were observed.

CONCLUSION

Exposure to palivizumab neither increased the risk of atopic disease nor protected against asthma.

Nasopharyngeal microbiome in premature infants and stability during rhinovirus infection

RATIONALE

The nasopharyngeal (NP) microbiota of newborns and infants plays a key role in modulating airway inflammation and respiratory symptoms during viral infections. Premature (PM) birth modifies the early NP environment and is a major risk factor for severe viral respiratory infections. However, it is currently unknown if the NP microbiota of PM infants is altered relative to full-term (FT) individuals.

OBJECTIVES

To characterize the NP microbiota differences in preterm and FT infants during rhinovirus (RV) infection.

METHODS

We determined the NP microbiota of infants 6 months to ≤2 years of age born FT (n=6) or severely PM<32 weeks gestation (n=7). We compared microbiota composition in healthy NP samples and performed a longitudinal analysis during naturally occurring RV infections to contrast the microbiota dynamics in PM versus FT infants.

RESULTS

We observed significant differences in the NP bacterial community of PM versus FT. NP from PM infants had higher within-group dissimilarity (heterogeneity) relative to FT infants. Bacterial composition of NP samples from PM infants showed increased Proteobacteria and decreased in Firmicutes. There were also differences in the major taxonomic groups identified, including Streptococcus, Moraxella, and Haemophilus. Longitudinal data showed that these prematurity-related microbiota features persisted during RV infection.

CONCLUSIONS

PM is associated with NP microbiota changes beyond the neonatal stage. PM infants have an NP microbiota with high heterogeneity relative to FT infants. These prematurity-related microbiota features persisted during RV infection, suggesting that the NP microbiota of PM may play an important role in modulating airway inflammatory and immune responses in this vulnerable group.

Comparative Assessment of Cytokine Pattern in Early and Late Onset of Neonatal Sepsis

Neonatal sepsis is a significant health issue associated with high mortality. Immune responses associated with neonatal sepsis, such as proinflammatory cytokine production, are believed to play a central role in the pathogenesis of this disease. In the present study, serum levels of the proinflammatory cytokines TNF-α, IL1-β, and IL-6 and the anti-inflammatory cytokines IL-4 and IL-10 were evaluated for 25 subjects with neonatal sepsis. We observed that subjects with late onset of sepsis (LOS), as well as those with early onset of sepsis (EOS), had a substantial increase in serum TNF-α. In contrast to EOS, subjects with LOS demonstrated a significant increase in serum levels IL-6 and IL-10. Additionally, we observed a significant difference in cytokine profiles between acute and postacute cases of neonatal sepsis. For instance, the level of proinflammatory cytokines, such as TNF-α and IL-6, was elevated in the acute phase, whereas the production of anti-inflammatory cytokines, such as IL-10, became substantially upregulated during the postacute phase. Additionally, no correlation was observed between cytokine levels and CRP levels or lymphocyte counts. Thus, in contrast to CRP levels and lymphocyte counts, examination of the cytokine profile can provide valuable information when determining the most effective therapy for treating neonatal sepsis. This information may be useful to physicians when determining if anti-inflammatory or immune stimulatory therapy is warranted.

Nrf2 regulates gene-environment interactions in an animal model of intrauterine inflammation: Implications for preterm birth and prematurity

Preterm birth (PTB) is the leading cause of neonatal mortality, and surviving infants are at increased risk for lifelong disabilities. Intrauterine inflammation is an etiological factor that drives PTB, and oxidative stress is associated with PTB. Nuclear erythroid 2-related factor 2 (Nrf2) is a redox-sensitive transcription factor that is the key regulator of the response to oxidative and inflammatory stress. Here, we used the established mouse model of intrauterine inflammation-induced PTB to determine whether Nrf2 is a modifier of susceptibility to PTB and prematurity-related morbidity and mortality in the offspring. We determined that Nr2-deficient (Nrf2^−/−) mice exhibited a greater sensitivity to intrauterine inflammation, as indicated by decreased time to delivery, reduced birthweight, and 100% mortality. Placentas from preterm Nrf2^−/− mice showed elevated levels of markers of inflammation, oxidative stress, and cell death, and transcriptomic analysis identified numerous key signaling pathways that were differentially expressed between wild-type (WT) and Nrf2^−/− mice in both preterm and control samples. Thus, Nrf2 could be a critical factor for gene-environment interactions that may determine susceptibility to PTB. Further studies are needed to determine if Nrf2 is a viable therapeutic target in women who are at risk for PTB and associated complications in the affected offspring.

Altered Intracellular ATP Production by Activated CD4+ T-Cells in Very Preterm Infants

Background. The neonatal immune system is not fully developed at birth; newborns have adequate lymphocytes counts but these cells lack function. Objective. To assess the activity of T-cells and the influence of the main perinatal factors in very preterm infants (birth weight < 1500 g). Design. Blood samples from 59 preterm infants (21/59 were dizygotic twins) were collected at birth and at 30 days of life to measure CD4+ T-cell activity using the ImmuKnow™ assay. Fifteen healthy adults were included as a control group. Results. CD4+ T-cell activity was lower in VLBW infants compared with adults (p < 0.001). Twins showed lower immune activity compared to singletons (p = 0.005). Infants born vaginally showed higher CD4+ T-cell activity compared to those born by C-section (p = 0.031); infants born after prolonged Premature Rupture of Membranes (pPROM) showed higher CD4+ T-cell activity at birth (p = 0.002) compared to infants born without pPROM. Low CD4+ T-cell activity at birth is associated with necrotizing enterocolitis (NEC) in the first week of life (p = 0.049). Conclusions. Preterm infants show a lack in CD4+ T-cell activity at birth. Perinatal factors such as intrauterine inflammation, mode of delivery, and zygosity can influence the adaptive immune activation capacity at birth and can contribute to exposing these infants to serious complications such as NEC.

Association between birth route and late-onset sepsis in very preterm neonates

OBJECTIVE

To evaluate the association between birth route and late-onset sepsis (LOS), and coagulase-negative Staphylococcal (CONS)-related LOS in preterm neonates.

STUDY DESIGN

In this observational study, data from 20,038 infants born between 22 and 32 weeks' gestation and admitted to Canadian neonatal intensive care units between 2010 and 2014 were analyzed retrospectively. The impact of birth route on LOS was assessed using univariate analysis and multiple logistic regression.

RESULTS

A total of 8218 neonates were born via vaginal route and 11,820 via cesarean section. Incidence rates of LOS for infants born vaginally and via a cesarean section were 13.1 and 13.2%, respectively, and there was no significant difference in odds of LOS between the groups (adjusted odds ratio (AOR): 0.99; 95% CI 0.87 to 1.12); however, the odds of CONS sepsis were higher in the cesarean group (AOR: 1.15; 95% CI: 1.01 to 1.32).

CONCLUSION

Birth route did not have an impact on LOS, but was associated with CONS-related LOS.

Artificial placenta: Analysis of recent progress

The artificial placenta (AP) has for many decades captured the imagination of scientists and authors with popular fiction including The Matrix and Aldous Huxley's "Brave New World", depicting a human surviving ex-utero in an artificial uterine environment (AUE). For scientists this has fascinated as a way forward for extremely preterm infants (EPIs) born less than 28 weeks of gestation. Early successes with mechanical ventilation (MV) for infants born above 28 weeks of gestation meant that AP research lost momentum. More recently, the gestational age limit for survival now borders on 23 weeks and corresponds to the biological milestone of lung development marked by the early canalicular stage of lung morphogenesis. The so called greyzone of 23-25 weeks represents a steep increase in mortality with decreasing gestational age and current options in neonatal care are on the fringes of efficacy for this population. A shift in thinking recognizes the vitality of EPIs as a fetus rather than a 37-40 week neonate and this has reinvigorated the concept of the AP. This review will discuss the scale of extreme preterm birth with special reference to previable infants born in the greyzone. Recent AP studies using sheep models are compared, technical obstacles discussed and future research themes identified.

Association of Gestational Age and Severe Neonatal Morbidity with Mortality in Early Childhood

BACKGROUND

Although infant and child mortality rates have decreased substantially worldwide over the past two decades, efforts continue in many nations to further these declines. The identification of pertinent perinatal factors that are associated with early childhood mortality would help with these efforts. We investigated the association of two crucial perinatal factors, gestational age and severe neonatal morbidity at birth, with mortality during infancy (29-364 days) and early childhood (1-5 years).

METHODS

The study population included all singleton livebirths, ≥32 weeks' gestation in New South Wales, Australia in 2001-11. Birth data were linked to hospitalisation morbidity data and deaths data (linked birth cohort n = 871 916), and multivariable Cox regression models were used to assess mortality.

RESULTS

The median follow-up time per child was 4.95 years (range 0.00-5.92 years; 3 614 738 total person-years), with 984 deaths observed. Gestational age was associated with increased mortality, and specifically from deaths attributable to infections, respiratory conditions, and injuries during infancy, but not during early childhood. Severe neonatal morbidity strongly mediated the effects of gestational age during infancy, but not during early childhood, and was associated with increased mortality from circulatory, nervous, and respiratory system causes.

CONCLUSIONS

The direct effects of gestational age on mortality extended up to 1 year of age, whereas severe neonatal morbidity remained associated with heightened mortality into early childhood. Efforts to maximise the health and well-being of vulnerable infants, with emphasis on preventing infections and injuries, may help further reduce early childhood mortality.

Lactoferrin and prematurity: a promising milk protein?

Lactoferrin (Lf) is the major whey protein in milk, with multiple beneficial health effects including direct antimicrobial activities, anti-inflammatory effects, and iron homeostasis. Oral Lf supplementation in human preterm infants has been shown to reduce the incidence of sepsis and necrotizing enterocolitis. In preclinical models of antenatal stress and perinatal brain injury, bovine Lf protected the developing brain from neuronal loss, improved connectivity, increased neurotrophic factors, and decreased inflammation. It also supported brain development and cognition. Further, Lf can prevent preterm delivery by reducing proinflammatory factors and inhibiting premature cervix maturation. We review here the latest research on Lf in the field of neonatology.

Age-Related Effect of Viral-Induced Wheezing in Severe Prematurity

Premature children are prone to severe viral respiratory infections in early life, but the age at which susceptibility peaks and disappears for each pathogen is unclear. Methods: A retrospective analysis was performed of the age distribution and clinical features of acute viral respiratory infections in full-term and premature children, aged zero to seven years. Results: The study comprised of a total of 630 hospitalizations (n = 580 children). Sixty-seven percent of these hospitalizations occurred in children born full-term (>37 weeks), 12% in preterm (32-37 weeks) and 21% in severely premature children (<32 weeks). The most common viruses identified were rhinovirus (RV; 60%) and respiratory syncytial virus (RSV; 17%). Age-distribution analysis of each virus identified that severely premature children had a higher relative frequency of RV and RSV in their first three years, relative to preterm or full-term children. Additionally, the probability of RV- or RSV-induced wheezing was higher overall in severely premature children less than three years old. Conclusions: Our results indicate that the vulnerability to viral infections in children born severely premature is more specific for RV and RSV and persists during the first three years of age. Further studies are needed to elucidate the age-dependent molecular mechanisms that underlie why premature infants develop RV- and RSV-induced wheezing in early life.

[Effect of perinatal factors on postnatal development of lymphocyte subsets in early preterm infants]

OBJECTIVE

To study the postnatal changes in lymphocyte subsets in early preterm infants and the effect of perinatal factors on lymphocyte subsets.

METHODS

A total of 61 early preterm infants were enrolled. Flow cytometry was used to measure the absolute counts of lymphocytes and lymphocyte subsets at 1, 7, 14, and 28 days after birth, as well as at 6 months after birth for 17 of these early preterm infants. The effects of perinatal factors, such as antepartum use of hormone, intrauterine infection, gestational age at birth, and Ureaplasma urealyticum (UU) colonization, on lymphocyte subsets were analyzed.

RESULTS

The absolute counts of lymphocyte subsets except natural killer (NK) cells were lowest at birth, increased rapidly at 1 week after birth, and reached the levels in healthy infants at 6 months; the count of NK cells remained at a low level and increased significantly at 6 months after birth. Compared with those with a gestational age of <28 weeks, the early preterm infants with a gestational age of ≥28 weeks had significantly higher absolute counts of T cells, T helper (Th) cells, and NK cells at 7 days after birth, a significantly higher absolute count of T cells at 14 days after birth, and significantly higher absolute counts of lymphocytes and Th cells at 28 days after birth (P<0.05). Compared with the group not using hormone, the group using hormone showed a significantly higher absolute count of T cells at 7 days after birth and significantly higher absolute counts of lymphocytes and all subsets at 14 days after birth (P<0.05). There was no significant difference in lymphocyte subsets at 1 day after birth between the intrauterine infection and non-infection groups (P>0.05); the intrauterine infection group had significantly higher absolute counts of B cells at 7 and 14 days after birth than the non-infection group. Compared those without UU colonization, the infants with UU colonization had significantly higher absolute counts of lymphocytes, T cells, Th cells, and Ts cells at 1 day after birth and a significantly higher absolute count of B cells at 14 days after birth.

CONCLUSIONS

Early preterm infants have deficiencies in innate immune cells at birth and normal levels at about 6 months after birth. Various perinatal factors including antepartum use of hormone, gestational age at birth, intrauterine infection, and UU colonization have long-term effects on lymphocyte subsets in early preterm infants.