Cord Blood Monocytes, Neutrophils and Lymphocytes from Preterm and Full-Term Neonates Show Multiple Aberrations in Signalling Profiles Measured Using Phospho-Specific Whole-Blood Flow Cytometry

Insulin-like growth factor 1 associated with altered immune responses in preterm infants and pigs

BACKGROUND

Preterm infants show low blood levels of insulin-like growth factor 1 (IGF-1), known to be negatively correlated with Interleukin-6 (IL-6). We hypothesized that circulating IGF-1 is associated with systemic immune-markers following preterm birth and that exogenous IGF-1 supplementation modulates immune development in preterm pigs, used as model for preterm infants.

METHODS

Plasma levels of IGF-1 and 29 inflammatory markers were measured in very preterm infants (n = 221). In preterm pigs, systemic immune development, assessed by in vitro challenge, was compared between IGF-1 treated (2.25 mg/kg/day) and control animals.

RESULTS

Preterm infants with lowest gestational age and birth weight showed the lowest IGF-1 levels, which were correlated not only with IL-6, but a range of immune-markers. IGF-1 supplementation to preterm pigs reduced plasma IL-10 and Interferon-γ (IFN-γ), IL-2 responses to challenge and reduced expression of genes related to Th1 polarization. In vitro addition of IGF-1 (100 ng/mL) further reduced the IL-2 and IFN-γ responses but increased IL-10 response.

CONCLUSIONS

In preterm infants, plasma IGF-1 correlated with several immune markers, while supplementing IGF-1 to preterm pigs tended to reduce Th1 immune responses. Future studies should document whether IGF-1 supplementation to preterm infants affects immune development and sensitivity to infection.

IMPACT

Supplementation of insulin-like growth factor 1 (IGF-1) to preterm infants has been proposed to promote postnatal growth, but its impact on the developing immune system is largely unknown. In a cohort of very preterm infants, low gestational age and birth weight were the primary predictors of low plasma levels of IGF-1, which in turn were associated with plasma immune markers. Meanwhile, in immature preterm pigs, experimental supplementation of IGF-1 reduced Th1-related immune responses in early life. Supplementation of IGF-1 to preterm infants may affect the developing immune system, which needs consideration when evaluating overall impact on neonatal health.

TLR Responses in Preterm and Term Infant Cord Blood Mononuclear Cells

Preterm infants are more susceptible to severe bacterial and viral infectious diseases than their full-term counterparts. A major contributor to this increased susceptibility may be due to differences in their ability to respond to pathogens. While studies have demonstrated altered bacterial Toll-like receptor (TLR) responses, there is limited data on viral TLR responses in preterm infants. In this study, cord blood mononuclear cells (CBMCs) from 10 moderately preterm (30.4-34.1 wGA), 10 term (37-39.5 wGA) infants, and 5 adults were stimulated with TLR2 (lipoteichoic acid), TLR3 (poly I:C), TLR4 (lipopolysaccharide), TLR7/8 (R848), and TLR9 (CpG-ODN 2216) agonists. Following stimulation, the cellular response was measured by intracellular flow cytometry to detect cell-specific NF-κB (as a marker of the inflammatory response), and multiplex assays were used to measure the cytokine response. This study found that preterm and term infants exhibit very similar baseline TLR expression. In response to both bacterial and viral TLR agonists comparing cell-specific NF-κB activation, preterm infants exhibited increased monocyte activation following LTA stimulation; however, no other differences were observed. Similarly, no difference in cytokine response was observed following stimulation with TLRs. However, a stronger correlation between NF-κB activation and cytokine responses was observed in term infants following poly I:C and R848 stimulation compared to preterm infants. In contrast, despite similar TLR expression, adults produced higher levels of IFN-α following R848 stimulation compared to preterm and term infants. These findings suggest preterm and term infants have a similar capacity to respond to both bacterial and viral TLR agonists. As preterm infants are more likely to develop severe infections, further research is required to determine the immunological factors that may be driving this and develop better interventions for this highly vulnerable group.

Comprehensive Morphological Assessment of Cord Blood: Normal Values and the Prevalence of Morphologically Aberrant Leukocytes

INTRODUCTION

Cord blood (CB) is becoming a valuable source for stem cells utilized in a variety of cell therapy applications, as well as for newborn diagnostics. Some parameters of the CB cellular components can be provided by automated analyzers, while others, such as immature or aberrant cells, require blood film morphological assessment. The objectives of the study were to establish normal CB morphology and to determine the prevalence of morphologically aberrant leukocytes in CB.

METHODS

We performed a comprehensive morphological analysis of 100 CB samples taken from healthy term and appropriate-for-gestational-age neonates born to healthy mothers, preterm neonates, neonates of diabetic mothers, and small-for-gestational-age neonates. Blood counts were assessed, and manual morphological analyses were performed by laboratory specialists.

RESULTS

The manual differential count of normal CB samples established the following values: 47.8 ± 10.7% neutrophils, 31.2 ± 9.8% lymphocytes, 10.0 ± 4.0% monocytes, and 3.0 ± 2.5% eosinophils, with no significant sex-related differences. Blasts were observed in 44/100 samples with an average of 0.5 ± 0.7% per sample, and only a minor left shift was observed. There were significant populations of large granular lymphocytes (19.1 ± 10.6% of the total lymphocytes) and morphologically aberrant lymphocytes (12.4 ± 5.4% of the total lymphocytes) in the samples, irrespective of neonatal status. The differentials of preterm CB samples differ significantly from normal term CB samples, including the reverse of neutrophils/lymphocytes ratio, and the lack of basophils.

CONCLUSIONS

Normal values and unique morphological features in the CB of neonates are described. The abundant morphologically aberrant lymphocytes in CB may represent an immature state of the immune system at birth.

Invasive Group B Streptococcus Disease With Recurrence and in Multiples: Towards a Better Understanding of GBS Late-Onset Sepsis

Group B Streptococcus (GBS) is a common intestinal colonizer during the neonatal period, but also may cause late-onset sepsis or meningitis in up to 0.5% of otherwise healthy colonized infants after day 3 of life. Transmission routes and risk factors of this late-onset form of invasive GBS disease (iGBS) are not fully understood. Cases of iGBS with recurrence (n=25) and those occurring in parallel in twins/triplets (n=32) from the UK and Ireland (national surveillance study 2014/15) and from Germany and Switzerland (retrospective case collection) were analyzed to unravel shared (in affected multiples) or fixed (in recurrent disease) risk factors for GBS disease. The risk of iGBS among infants from multiple births was high (17%), if one infant had already developed GBS disease. The interval of onset of iGBS between siblings was 4.5 days and in recurrent cases 12.5 days. Disturbances of the individual microbiome, including persistence of infectious foci are suggested e.g. by high usage of perinatal antibiotics in mothers of affected multiples, and by the association of an increased risk of recurrence with a short term of antibiotics [aOR 4.2 (1.3-14.2), P=0.02]. Identical GBS serotypes in both recurrent infections and concurrently infected multiples might indicate a failed microbiome integration of GBS strains that are generally regarded as commensals in healthy infants. The dynamics of recurrent GBS infections or concurrent infections in multiples suggest individual patterns of exposure and fluctuations in host immunity, causing failure of natural niche occupation.

Genetic variants associated with patent ductus arteriosus in extremely preterm infants

OBJECTIVE

Patent ductus arteriosus (PDA) is a commonly observed condition in preterm infants. Prior studies have suggested a role for genetics in determining spontaneous ductal closure. Using samples from a large neonatal cohort we tested the hypothesis that common genetic variations are associated with PDA in extremely preterm infants.

STUDY DESIGN

Preterm infants (n = 1013) enrolled at NICHD Neonatal Research Network sites were phenotyped for PDA. DNA was genotyped for 1634 single nucleotide polymorphisms (SNPs) from candidate genes. Analyses were adjusted for ancestral eigenvalues and significant epidemiologic variables.

RESULTS

SNPs in several genes were associated with the clinical diagnosis of PDA and with surgical ligation in extremely preterm neonates diagnosed with PDA (p < 0.01). None of the associations were significant after correction for multiple comparisons.

CONCLUSION

We identified several common genetic variants associated with PDA. These findings may inform further studies on genetic risk factors for PDA in preterm infants.

Prevalence of early and late prematurity is similar among pediatric type 1 diabetes patients and the general population

BACKGROUND

The incidence of type 1 diabetes mellitus (T1DM) has increased in recent decades, as has the incidence of preterm births (<37 weeks). We aimed to evaluate and compare the prevalence of prematurity and early prematurity (<34 weeks) and birth season variability among T1DM and non-T1DM children.

METHODS

A nationwide cross-sectional study was conducted, with linkage of data from 13 paediatric diabetes centers and Israeli National Registries, including T1DM patients and general non-T1DM population, born during 2000 to 2013. Gathered data included ethnicity, gender, birth week, weight, and season. The prevalence of prematurity and birth season were compared with the general population birth registry using Pearson Chi-square test.

RESULTS

The study population included 1452 T1DM patients, 52.7% males, and 2 138 668 subjects in the general non-T1DM population, 51.2% males. The prevalence of late and early prematurity was similar between groups (6.1% and 2.2% in the T1DM group vs 5.6% and 2.0% in the general non-T1DM group, P = 0.25 and P = 0.38, respectively). OR for prematurity among T1DM patients was 1.15 (0.95-1.39), P = 0.16. No difference in birth season was demonstrated between preterm and term, in T1DM and general non-T1DM populations. Ethiopian descent was more prevalent among T1DM patients compared with the non-T1DM population, in both term and preterm born.

CONCLUSIONS

This is the largest population-based study, and the first in the Middle East geographical area, indicating that prematurity, including early prematurity, is not associated with T1DM during childhood. The study was registered at https://clinicaltrials.gov/: NCT02929953.

Exposure to chorioamnionitis alters the monocyte transcriptional response to the neonatal pathogen Staphylococcus epidermidis

Preterm infants are uniquely susceptible to late-onset sepsis that is frequently caused by the skin commensal Staphylococcus epidermidis. Innate immune responses, particularly from monocytes, are a key protective mechanism. Impaired cytokine production by preterm infant monocytes is well described, but few studies have comprehensively assessed the corresponding monocyte transcriptional response. Innate immune responses in preterm infants may be modulated by inflammation such as prenatal exposure to histologic chorioamnionitis which complicates 40-70% of preterm pregnancies. Chorioamnionitis alters the risk of late-onset sepsis, but its effect on monocyte function is largely unknown. Here, we aimed to determine the impact of exposure to chorioamnionitis on the proportions and phenotype of cord blood monocytes using flow cytometry, as well as their transcriptional response to live S. epidermidis. RNA-seq was performed on purified cord blood monocytes from very preterm infants (<32 weeks gestation, with and without chorioamnionitis-exposure) and term infants (37-40 weeks), pre- and postchallenge with live S. epidermidis. Preterm monocytes from infants without chorioamnionitis-exposure did not exhibit an intrinsically deficient transcriptional response to S. epidermidis compared to term infants. In contrast, chorioamnionitis-exposure was associated with hypo-responsive transcriptional phenotype regarding a subset of genes involved in antigen presentation and adaptive immunity. Overall, our findings suggest that prenatal exposure to inflammation may alter the risk of sepsis in preterm infants partly by modulation of monocyte responses to pathogens.

Neurocognitive Outcomes at 10 Years of Age in Extremely Preterm Newborns with Late-Onset Bacteremia

OBJECTIVE

To evaluate the difference in 10-year neurocognitive outcomes between extremely low gestational age newborns without bacteremia and those with suspected or confirmed late-onset bacteremia.

STUDY DESIGN

Neurocognitive function was evaluated at 10 years of age in 889 children born at <28 weeks of gestation and followed from birth. Definite (culture-positive) late-onset bacteremia during postnatal weeks 2-4 was identified in 223 children, and 129 children had suspected bacteremia.

RESULTS

Infants with the lowest gestational age and birth weight z-score had the highest prevalence of definite and suspected late-onset bacteremia. Compared with peers with no or suspected bacteremia, infants with definite bacteremia performed worse on tests of general cognitive ability, language, academic achievement, and executive function, even after adjustment for potential confounders. Adjustment for low IQ attenuated the associations between bacteremia and all dysfunctions at age 10 years. Children with suspected bacteremia did not differ appreciably from those with no evidence of bacteremia. The motor domain was unaffected.

CONCLUSIONS

Extremely low gestational age newborns who had definite late bacteremia during postnatal weeks 2-4 are at heightened risk of neurocognitive limitations at age 10 years.

Distinct mechanisms of the newborn innate immunity

The ontogeny of immunity during early life is of high importance as it shapes the immune system for the entire course of life. The microbiome and the environment contribute to the development of immunity in newborns. As immune responses in newborns are predominantly less experienced they are increasingly susceptible to infections. Though the immune cells in newborns are in 'naïve' state, they have been shown to mount adult-like responses in several circumstances. The innate immunity plays a vital role in providing protection during the neonatal period. Various stimulants have been shown to enhance the potential and functioning of the innate immune cells in newborns. They are biased against the production of pro-inflammatory cytokines and this makes them susceptible to wide variety of intracellular pathogens. The adaptive immunity requires prior antigenic experience which is very limited in newborns. This review discusses in detail the characteristics of innate immunity in newborns and the underlying developmental and functional mechanisms involved in the immune response. A better understanding of the immunological milieu in newborns could help the medical fraternity to find novel methods for prevention and treatment of infection in newborns.

Constitutive STAT3 Phosphorylation in Circulating CD4+ T Lymphocytes Associates with Disease Activity and Treatment Response in Recent-Onset Rheumatoid Arthritis

The aim of the present study was to examine constitutive signal transducer and activator of transcription 3 (STAT3) phosphorylation in circulating leukocytes as a candidate biomarker in rheumatoid arthritis (RA). 25 patients with recent-onset, untreated RA provided samples for whole blood flow cytometric determination of intracellular STAT3 phosphorylation, expressed as relative fluorescence units. The occurrence of constitutive STAT3 phosphorylation was evaluated by determining proportion of STAT3-phosphorylated cells among different leukocyte subtypes. Plasma levels of interleukin (IL)-6, IL-17 and IL-21 were measured by immunoassay, radiographs of hands and feet were examined and disease activity score (DAS28) was determined. Biomarkers were restudied and treatment response (according to European League Against Rheumatism) was determined after 12 months of treatment with disease-modifying antirheumatic drugs. At baseline, constitutive phosphorylation of STAT3 occurred in CD4⁺ T cells of 14 (56%) patients, CD8⁺ T cells of 13 (52%) patients, in CD19⁺ B cells of 7 (28%) patients, and in CD14⁺ monocytes of 12 (48%) patients. STAT3 phosphorylation levels of CD4⁺ T cells associated with DAS28, and those of all leukocyte subtypes studied associated with erosive disease. The presence of constitutive STAT3 phosphorylation in CD4⁺ T lymphocytes, pSTAT3 fluorescence intensity of CD4⁺ and CD8⁺ T cells and C-reactive protein (CRP) levels at baseline associated with good treatment response. In conclusion, constitutive STAT3 phosphorylation in circulating CD4⁺ T cells is common in recent-onset untreated RA and associates with good treatment response in patients characterized by high disease activity and the presence of systemic inflammation.

Naïve T cells, unconventional NK and NKT cells, and highly responsive monocyte-derived macrophages characterize human cord blood

This study compares the human immune systems of neonates and adults. Flow cytometric analysis was used to study the cellular phenotypes of cord blood (CB) and adult peripheral blood (APB). Luminex analysis was used to determine the levels of cytokines in cell culture supernatants. Our findings indicate that T cells in CB were mainly naïve and thus less responsive to PMA/ionomycin with the synthesis of cytokines. The percentages of CD3(+)CD4(+)CD25(high) and of CD3(+)CD4(+)CD25(dim) cells expressing chemokine receptors were different between CB and APB. TLR1, TLR6 and TLR9 expressions on NK and NKT cells also differed between CB and APB. CB monocyte-derived macrophages responded better than APB macrophages to TLR ligands with increased secretion of inflammatory cytokines, especially IL-6. The high levels of the inflammatory cytokines in cell culture supernatants of CB were mainly due to higher numbers of responsive macrophages, since dendritic cell numbers were lower in CB than APB.