Nucleated red blood cell counts in the first week of life: a critical appraisal of relationships with perinatal outcome in preterm growth-restricted neonates

Do hematological biomarkers predict surgical necrotizing enterocolitis?

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal emergency in preterm infants and the clinical presentation of NEC may vary with gestational age. We lack reliable biomarkers for early diagnosis of NEC limiting timely intervention. Hematological changes in NEC are actively researched for their potential role as biomarkers. The pattern and severity of hematological abnormalities have been correlated with rapid progression, the need for surgery, increased risk of mortality, and morbidity. In this issue of Pediatric Research, Chong et al. report GA-specific hematological biomarkers in preterm infants with NEC that could predict the need for surgery. Thrombocytopenia at NEC onset was an independent predictor of surgical intervention in extremely preterm infants. Persistent thrombocytopenia and lymphopenia at 72 h and elevated C-reactive protein at 48 h after NEC onset, predicted surgery in infants of 28 to <32 weeks GA. Persistent thrombocytopenia at 24 h after the onset of NEC was predictive of mortality in infants who underwent surgery. Well-designed, prospective, multi-center studies are needed to confirm the role of hematological biomarkers in early diagnosis and prognostication in NEC.

Epigenomic signature of major congenital heart defects in newborns with Down syndrome

BACKGROUND

Congenital heart defects (CHDs) affect approximately half of individuals with Down syndrome (DS), but the molecular reasons for incomplete penetrance are unknown. Previous studies have largely focused on identifying genetic risk factors associated with CHDs in individuals with DS, but comprehensive studies of the contribution of epigenetic marks are lacking. We aimed to identify and characterize DNA methylation differences from newborn dried blood spots (NDBS) of DS individuals with major CHDs compared to DS individuals without CHDs.

METHODS

We used the Illumina EPIC array and whole-genome bisulfite sequencing (WGBS) to quantitate DNA methylation for 86 NDBS samples from the California Biobank Program: (1) 45 DS-CHD (27 female, 18 male) and (2) 41 DS non-CHD (27 female, 14 male). We analyzed global CpG methylation and identified differentially methylated regions (DMRs) in DS-CHD versus DS non-CHD comparisons (both sex-combined and sex-stratified) corrected for sex, age of blood collection, and cell-type proportions. CHD DMRs were analyzed for enrichment in CpG and genic contexts, chromatin states, and histone modifications by genomic coordinates and for gene ontology enrichment by gene mapping. DMRs were also tested in a replication dataset and compared to methylation levels in DS versus typical development (TD) WGBS NDBS samples.

RESULTS

We found global CpG hypomethylation in DS-CHD males compared to DS non-CHD males, which was attributable to elevated levels of nucleated red blood cells and not seen in females. At a regional level, we identified 58, 341, and 3938 CHD-associated DMRs in the Sex Combined, Females Only, and Males Only groups, respectively, and used machine learning algorithms to select 19 Males Only loci that could distinguish CHD from non-CHD. DMRs in all comparisons were enriched for gene exons, CpG islands, and bivalent chromatin and mapped to genes enriched for terms related to cardiac and immune functions. Lastly, a greater percentage of CHD-associated DMRs than background regions were differentially methylated in DS versus TD samples.

CONCLUSIONS

A sex-specific signature of DNA methylation was detected in NDBS of DS-CHD compared to DS non-CHD individuals. This supports the hypothesis that epigenetics can reflect the variability of phenotypes in DS, particularly CHDs.

Epigenomic signature of major congenital heart defects in newborns with Down syndrome

Background

Congenital heart defects (CHDs) affect approximately half of individuals with Down syndrome (DS) but the molecular reasons for incomplete penetrance are unknown. Previous studies have largely focused on identifying genetic risk factors associated with CHDs in individuals with DS, but comprehensive studies of the contribution of epigenetic marks are lacking. We aimed to identify and characterize DNA methylation differences from newborn dried blood spots (NDBS) of DS individuals with major CHDs compared to DS individuals without CHDs.

Methods

We used the Illumina EPIC array and whole-genome bisulfite sequencing (WGBS) to quantitate DNA methylation for 86 NDBS samples from the California Biobank Program: 1) 45 DS-CHD (27 female, 18 male) and 2) 41 DS non-CHD (27 female, 14 male). We analyzed global CpG methylation and identified differentially methylated regions (DMRs) in DS-CHD vs DS non-CHD comparisons (both sex-combined and sex-stratified) corrected for sex, age of blood collection, and cell type proportions. CHD DMRs were analyzed for enrichment in CpG and genic contexts, chromatin states, and histone modifications by genomic coordinates and for gene ontology enrichment by gene mapping. DMRs were also tested in a replication dataset and compared to methylation levels in DS vs typical development (TD) WGBS NDBS samples.

Results

We found global CpG hypomethylation in DS-CHD males compared to DS non-CHD males, which was attributable to elevated levels of nucleated red blood cells and not seen in females. At a regional level, we identified 58, 341, and 3,938 CHD-associated DMRs in the Sex Combined, Females Only, and Males Only groups, respectively, and used machine learning algorithms to select 19 Males Only loci that could distinguish CHD from non-CHD. DMRs in all comparisons were enriched for gene exons, CpG islands, and bivalent chromatin and mapped to genes enriched for terms related to cardiac and immune functions. Lastly, a greater percentage of CHD-associated DMRs than background regions were differentially methylated in DS vs TD samples.

Conclusions

A sex-specific signature of DNA methylation was detected in NDBS of DS-CHD compared to DS non-CHD individuals. This supports the hypothesis that epigenetics can reflect the variability of phenotypes in DS, particularly CHDs.

Nucleated red blood cells as a biomarker for mortality in infants and neonates requiring veno-arterial extracorporeal membrane oxygenation for cardiac disease

INTRODUCTION

Nucleated red blood cells (NRBC) are rare in the peripheral circulation of healthy individuals and their presence have been associated with mortality in adults and very low birth weight newborns, however, its value as a biomarker for mortality in infants requiring veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) has yet to be studied. We sought to determine if NRBC can serve as a biomarker for ECMO mortality and inpatient mortality in infants requiring V-A ECMO.

METHODS

A single-center retrospective chart review analyzing infants <1 year of age requiring VA ECMO due to myocardial dysfunction or post-cardiotomy between January 1, 2011 to June 30, 2020.

RESULTS

One hundred two patients required VA ECMO. Sixty-five patients required ECMO post-cardiotomy, 19 for perioperative deterioration, and 18 for myocardial dysfunction. Fifty-one patients (50%) died (21 died on ECMO, 30 died post-ECMO decannulation). Multivariable analysis found Age <60 days (OR 13.0, 95% CI 1.9-89.6, p = 0.009), NRBC increase by >50% post-ECMO decannulation (OR 17.1, 95% CI 3.1-95.1, p = 0.001), Single Ventricle (OR 9.0, 95% CI 1.7-47.7, p = 0.01), and lactate at ECMO decannulation (OR 3.0, 95% CI 1.3-7.1, p = 0.011) to be independently associated with inpatient mortality. ROC curves evaluating NRBC pre-ECMO decannulation as a biomarker for mortality on ECMO (AUC 0.80, 95% CI 0.68-0.92, p ⩽ 0.001) and post-ECMO decannulation (AUC 0.75, 95% CI 0.65-0.84, p ⩽ 0.001) show NRBC to be an accurate biomarker for mortality.

CONCLUSIONS

Greater than 50% increase in NRBC post-ECMO decannulation is associated with inpatient mortality. NRBC value pre-ECMO decannulation may be a useful biomarker for mortality while on ECMO and post-decannulation.

Nucleated red blood cells as a biomarker for mortality in neonates following cardiac surgery

INTRODUCTION

Nucleated red blood cells (NRBCs) are immature red cells that under normal conditions are not present in the peripheral circulation. Several studies have suggested an association between elevated NRBC and poor outcome in critically ill adults and neonates. We sought to determine if elevations in NRBC value following cardiac surgery and following clinical events during the hospital stay can be used as a biomarker to monitor for mortality risk in neonates post-cardiac surgery.

MATERIALS AND METHODS

We constructed a retrospective study of 264 neonates who underwent cardiac surgery at Children's Hospital, New Orleans between 2011 and 2020. Variables included mortality and NRBC value were recorded following cardiac surgery and following peri-operative clinical events. The study was approved by LSU Health IRB. Sensitivity, specificity, receiver operating characteristic (ROC) curves with area under the curve (AUC) and logistic regression analysis were performed.

RESULTS

Thirty-six patients (13.6%) died, of which 32 had an NRBC value ≥10/100 white blood cell (WBC) during hospitalisation. Multi-variable analysis found extracorporeal membrane oxygenation use (OR 10, 95% CI 2.9-33, p=<0.001), NRBC ≥10/100 WBC (OR 16.1, CI 4.1-62.5, p ≤ 0.001) and peak NRBC in the 14-day period post-cardiac surgery (continuous variable, OR 1.05, 95% CI 1.0-1.09, p = 0.03), to be independently associated with mortality. Using a cut-off NRBC value of 10/100 WBC, there was an 88.9% sensitivity and a 90.8% specificity, with ROC curve showing an AUC of 0.9 and 0.914 for peak NRBC value in 14 days post-surgery and entire hospitalisation, respectively.

CONCLUSIONS

NRBC ≥10/100 WBC post-cardiac surgery is strongly associated with mortality. Additionally, NRBC trend appears to show promise as an accurate biomarker for mortality.

Peripheral Nucleated Red Blood Cells and Mortality in Critically Ill Children

The present retrospective cohort study examines whether there is an association between circulating nucleated red blood cells (nRBCs) and mortality in critically ill children. nRBCs are erythropoietic progenitor cells not found in peripheral blood of healthy adults and children beyond the neonatal period. The presence of circulating nRBCs is associated with poor prognosis in adults and neonates, though little is known about their significance in children. Admissions to both the general and cardiac pediatric intensive care unit at the Stollery Children's Hospital in Edmonton, Alberta between January 1, 2015 and December 31, 2017 were examined, and logistic regression was performed to ascertain the association between the peak absolute nRBC counts and in-hospital mortality in critically ill children. A total of 2065 admissions were included. The number of admissions with detectable nRBCs was 386 (prevalence: 13.9%), and the number of deaths was 93 (mortality: 4.5%). A statistically significant association was found between the absolute value of nRBC peak and intensive care unit mortality (odds ratio=1.37; 95% confidence interval: 1.13-1.67; P=0.002) as well as hospital mortality (odds ratio=1.38; 95% confidence interval: 1.12-1.70; P=0.003) independent of the Pediatric Index of Mortality 3 score (PIM3). This result warrants more attention to nRBC values and their potential clinical use.

Nucleated Red Blood Cells: Could They Be Indicator Markers of Illness Severity for Neonatal Intensive Care Unit Patients?

Background: We aimed to assess whether nucleated red blood cells (NRBCs) count could serve as a diagnostic and prognostic biomarker for morbidity and mortality in critically ill neonates. Methods: The association between NRBCs count and neonatal morbidity and mortality was evaluated in an observational cohort of critically ill neonates hospitalized in our neonatal intensive care unit over a period of 69 months. The discriminative ability of NRBCs count as diagnostic and prognostic biomarkers was evaluated by performing the Receiver Operating Characteristics (ROC) curve analysis. Results: Among 467 critically ill neonates included in the study, 45 (9.6%) of them experienced in-hospital mortality. No statistically significant difference was found with regards to NRBCs count between survivors and non-survivors, although the median value for NRBCs was sometimes higher for non-survivors. ROC curve analysis showed that NRBCs is a good discriminator marker for the diagnosis of perinatal hypoxia in neonates with area under the curve (AUC) [AUC 0.710; 95% confidence interval (CI), 0.660–0.759] and predominantly in preterm neonates (AUC 0.921 (95% CI, 0.0849–0.0993)) by using a cut-off value of ≥11.2%, with 80% sensitivity and 88.7% specificity. NRBCs also revealed significant prognostic power for mortality in septic neonates (AUC 0.760 (95% CI, 0.631–0.888)) and especially in preterms with sepsis (AUC 0.816 (95% CI, 0.681–0.951)), with cut-off value ≥ 1%, resulting in 81.6% sensitivity and 78.1% specificity. Conclusion: NRBCs count may be included among the early diagnostic and prognostic markers for sick neonates.

Nucleated red blood cells and serum lactate values on days 2 and 5 are associated with mortality and morbidity in VLBW infants

AIM

To correlate nucleated red blood cell counts and serum lactate concentrations on day 2 and 5 of life with morbidity and mortality in very low birth weight infants and to determine corresponding cutoff values.

METHODS

Retrospective analysis in a cohort of very low birth weight infants.

RESULTS

250 very low birth weight infants were included in this study. Gestational age ranged from 23 to 35 weeks (mean 29.04) and birth weight was 320-1500 g (mean 1047.9). 55 (22%) patients developed intraventricular hemorrhage, 55 (22%) bronchopulmonary dysplasia, 12 (4.8%) periventricular leukomalacia, 93 (37.2%) retinopathy of prematurity, and 1 (0.4%) necrotizing enterocolitis. Mortality rate was 25/250 (10%). Nucleated red blood cells and serum lactate on day 2 of life were associated with mortality (p < 0.001). Serum lactate on day 5 of life demonstrated an association with retinopathy of prematurity (p = 0.017), bronchopulmonary dysplasia (p = 0.044), and intraventricular hemorrhage (p < 0.001). Cutoff values predicting mortality were >89.5 nucleated red blood cells/100 leucocytes (sensitivity 68.2%, specificity 89.0%) and serum lactate concentrations >8.5 mmol/l (sensitivity 69.6%, specificity 93.5%) on day 2 of life.

CONCLUSION

We conclude that both nucleated red blood cell count and serum lactate concentration are valuable biomarkers in predicting important outcome parameters in very low birth weight infants.

Cord blood buffy coat DNA methylation is comparable to whole cord blood methylation

Cord blood DNA methylation is associated with numerous health outcomes and environmental exposures. Whole cord blood DNA reflects all nucleated blood cell types, while centrifuging whole blood separates red blood cells, generating a white blood cell buffy coat. Both sample types are used in DNA methylation studies. Cell types have unique methylation patterns and processing can impact cell distributions, which may influence comparability. We evaluated differences in cell composition and DNA methylation between cord blood buffy coat and whole cord blood samples. Cord blood DNA methylation was measured with the Infinium EPIC BeadChip (Illumina) in eight individuals, each contributing buffy coat and whole blood samples. We analyzed principal components (PC) of methylation, performed hierarchical clustering, and computed correlations of mean-centered methylation between pairs. We conducted moderated t-tests on single sites and estimated cell composition. DNA methylation PCs were associated with individual (PPC1 = 1.4 × 10-9; PPC2 = 2.9 × 10-5; PPC3 = 3.8 × 10-5; PPC4 = 4.2 × 10-6; PPC5 = 9.9 × 10-13, PPC6 = 1.3 × 10-11) and not with sample type (PPC1-6>0.7). Samples hierarchically clustered by individual. Pearson correlations of mean-centered methylation between paired samples ranged from r = 0.66 to r = 0.87. No individual site significantly differed between buffy coat and whole cord blood when adjusting for multiple comparisons (five sites had unadjusted P<10-5). Estimated cell type proportions did not differ by sample type (P = 0.46), and estimated proportions were highly correlated between paired samples (r = 0.99). Differences in methylation and cell composition between buffy coat and whole cord blood are much lower than inter-individual variation, demonstrating that both sample preparation types can be analytically combined and compared.

Differential DNA methylation at birth associated with mental disorder in individuals with 22q11.2 deletion syndrome

Individuals with 22q11.2 deletion syndrome (DS) have an increased risk of comorbid mental disorders including schizophrenia, attention deficit hyperactivity disorder, depression, as well as intellectual disability. Although most 22q11.2 deletion carriers have the long 3-Mb form of the hemizygous deletion, there remains a large variation in the development and progression of psychiatric disorders, which suggests that alternative factors contribute to the pathogenesis. In this study we investigated whether neonatal DNA methylation signatures in individuals with the 22q11.2 deletion associate with mental disorder later in life. DNA methylation was measured genome-wide from neonatal dried blood spots in a cohort of 164 individuals with 22q11.2DS, including 48 individuals diagnosed with a psychiatric disorder. Among several CpG sites with P-value<10-6, we identified cg23546855 (P-value=2.15 × 10-7) mapping to STK32C to be associated with a later psychiatric diagnosis. Pathway analysis of the top findings resulted in the identification of several Gene Ontology pathways to be significantly enriched (P-value<0.05 after Benjamini-Hochberg correction); among them are the following: neurogenesis, neuron development, neuron projection development, astrocyte development, axonogenesis and axon guidance. In addition, we identified differentially methylated CpG sites in LRP2BP (P-value=5.37 × 10-8) to be associated with intellectual disability (F70-79), in TOP1 (P-value=1.86 × 10-7) with behavioral disorders (F90-98), in NOSIP (P-value=5.12 × 10-8) with disorders of psychological development (F80-89) and in SEMA4B (P-value=4.02 × 10-7) with schizophrenia spectrum disorders (F20-29). In conclusion, our study suggests an association of DNA methylation differences at birth with development of mental disorder later in life in 22q11.2DS individuals.

Reference values for nucleated red blood cells and serum lactate in very and extremely low birth weight infants in the first week of life

STUDY PURPOSE

To provide reference values for nucleated red blood cells and serum lactate concentrations in very and extremely low birth weight (VLBW/ELBW) infants in the first week of life.

PATIENTS AND METHODS

Retrospective data analysis of serial, daily measurements of NRBC counts and serum lactate during the first 6days of life in VLBW and ELBW infants.

RESULTS

In total, 250 infants<1500g were included in this study. Intrauterine growth retardation (IUGR) was seen in 87 (34.8%) patients. Gestational age (GA) ranged from 23 to 35weeks (mean 29.0weeks) and birth weight (BW) was 320-1499g (mean 1047.9g). During hospital stay, 55 (22%) patients developed IVH and 55 children (22%) BPD. PVL was seen in 12 (4.8%) cases, ROP in 93 (37.2%) and NEC in only 1 (0.4%) patient. NRBC counts as well as serum lactate concentrations depended significantly on birth weight (p<0.01) and presence respectively absence of IUGR (p<0.01). Both NRBC counts and serum lactate concentrations declined constantly during the 6-day period (p<0.01), and both were highly inter-correlated (p<0.01).

CONCLUSIONS

This is one of only a very few studies that systematically and serially evaluated both NRBC counts and serum lactate concentration in VLBW and ELBW infants in the first 6days of life. Both parameters were significantly dependent on birth weight and the presence of IUGR. Moreover, a significant correlation between NRBC counts and serum lactate concentrations in this early period of life could be demonstrated. In future studies, the role of these readily available biomarkers in predicting important neonatal outcome parameters needs to be evaluated in a prospective manner.

Nucleated red blood cells count as a prognostic biomarker in predicting the complications of asphyxia in neonates

OBJECTIVE

Nucleated-red-blood-cells (NRBC) count in umbilical cord of newborns is been suggested as a sign of birth asphyxia. The present study was conducted to explore the value of NRBC count in prognosis of asphyxiated neonates.

METHODS

Sixty-three neonates with asphyxia were followed up for two years. Maternal and neonatal information was recorded follow by clinical and laboratory evaluation. NRBC-level was determined per 100 white-blood-cells (WBC). After discharge, follow-up of asphyxiated infants was performed using Denver II test at 6, 12, 18 and 24 months. Neonates were divided into two groups, with favorable and unfavorable outcome based on developmental delay or death.

RESULTS

We observed that NRBC count with more than 11 per 100 WBC, had sensitivity of 85% and specificity of 90% in predicting complications of asphyxia, while in absolute NRBC count with more than 1554, the sensitivity and specificity were 85% and of 87%, respectively. Combination of NRBC + HIE (hypoxic ischemic encephalopathy) grade had a high-predictive power for determining the prognosis of asphyxia in neonates.

CONCLUSION

We demonstrate that NRBC/100 WBC and absolute NRCB count can be used as prognostic marker for neonatal asphyxia, which in combination with the severity of asphyxia could indicate high infant mortality, and complications of asphyxia. Further studies in a larger and multi center setting trail are warranted to investigate the value of NRBC and HIE in asphyxiate term infants.

Birth weight-for-gestational age is associated with DNA methylation at birth and in childhood

BACKGROUND

Both higher and lower fetal growth are associated with cardio-metabolic health later in life, suggesting that prenatal developmental programming determines long-term cardiovascular disease risk. Epigenetic mechanisms, which orchestrate fetal growth and development, may offer insight on the early programming of health and disease. We investigated whether birth weight-for-gestational is associated with DNA methylation at birth and mid-childhood, measured via the Infinium 450K array.

METHODS/RESULTS

Participants were from Project Viva, a pre-birth cohort of pregnant women and their children in Eastern Massachusetts. After exclusion of participants with maternal type 1 or 2 diabetes and gestational age <34 weeks, we used DNA methylation assays from 476 venous umbilical cord blood samples and a subset of 235 who additionally had peripheral blood samples available in mid-childhood (age 7-10 years). Among 392,918 CpG sites analyzed, birth weight-for-gestational age z-score was associated with cord blood DNA methylation at 34 CpGs (false discovery rate P < 0.05), after adjusting for maternal age, race/ethnicity, education, smoking, parity, delivery mode, pre-pregnancy BMI, gestational diabetes status, child sex, and estimated cord blood cell proportions based on a cord blood reference panel. Two of these CpGs were previously reported in epigenome-wide analyses of birth weight, and several other CpGs map to genes relevant to fetal growth and development. Namely, higher birth weight-for-gestational age was associated with higher methylation at four CpGs at the PBX1 locus (e.g., β (95% CI) for lead signal at cg06750897 = 1.9 (1.2, 2.6)), which encodes a transcription factor that regulates embryonic development. Birth weight-for-gestational age was also associated with mid-childhood blood DNA methylation at four of the 34 CpGs identified in cord blood analyses, including sites at the PBX1 locus described.

CONCLUSIONS

We identified CpG sites where birth weight-for-gestational age was associated with DNA methylation at birth, and for a subset of these sites, birth weight-for-gestational age was also associated with DNA methylation at mid-childhood.

Characterizing the hypomethylated DNA methylation profile of nucleated red blood cells from cord blood

AIM

To provide insight into fetal nucleated red blood cell (nRBC) development using genome-wide DNA methylation (DNAm) profiling.

MATERIALS & METHODS

The DNAm profile (Illumina 450K array) of cord blood (n = 7) derived nRBCs was compared with B cells, CD4 and CD8 T cells, natural killer cells, granulocytes, monocytes and placenta (n = 5).

RESULTS

nRBCs and placenta had similarly low array-wide DNAm compared with white blood cells, but their patterns of hypomethylation differed at biologically relevant subsets of the array. High interindividual variability in nRBC DNAm was driven by a negative association between DNAm and nRBC count.

CONCLUSION

nRBC hypomethylation is likely an epigenetic signature of erythropoiesis rather than of early development. Variability in nRBC DNAm may stem from differences in the cell population's maturity or hematopoietic source.

DNA methylation of cord blood cell types: Applications for mixed cell birth studies

Epigenome-wide association studies of disease widely use DNA methylation measured in blood as a surrogate tissue. Cell proportions can vary between people and confound associations of exposure or outcome. An adequate reference panel for estimating cell proportions from adult whole blood for DNA methylation studies is available, but an analogous cord blood cell reference panel is not yet available. Cord blood has unique cell types and the epigenetic signatures of standard cell types may not be consistent throughout the life course. Using magnetic bead sorting, we isolated cord blood cell types (nucleated red blood cells, granulocytes, monocytes, natural killer cells, B cells, CD4(+)T cells, and CD8(+)T cells) from 17 live births at Johns Hopkins Hospital. We confirmed enrichment of the cell types using fluorescence assisted cell sorting and ran DNA from the separated cell types on the Illumina Infinium HumanMethylation450 BeadChip array. After filtering, the final analysis was on 104 samples at 429,794 probes. We compared cell type specific signatures in cord to each other and methylation at 49.2% of CpG sites on the array differed by cell type (F-test P < 10(-8)). Differences between nucleated red blood cells and the remainder of the cell types were most pronounced (36.9% of CpG sites at P < 10(-8)) and 99.5% of these sites were hypomethylated relative to the other cell types. We also compared the mean-centered sorted cord profiles to the available adult reference panel and observed high correlation between the overlapping cell types for granulocytes and monocytes (both r=0.74), and poor correlation for CD8(+)T cells and NK cells (both r=0.08). We further provide an algorithm for estimating cell proportions in cord blood using the newly developed cord reference panel, which estimates biologically plausible cell proportions in whole cord blood samples.

Nucleated red blood cells as marker for an increased risk of unfavorable outcome and mortality in very low birth weight infants

BACKGROUND

Nucleated red blood cells (NRBC) are normoblastic cells that failed to extrude their nuclei before exiting from bone marrow or liver. While NRBC are frequently found in umbilical cord blood after fetal distress, NRBC counts drop rapidly after birth.

AIMS

To determine the predictive value of the NRBC count during the first 120h after birth as marker for later risk of unfavorable outcome in very preterm infants.

STUDY DESIGN

This cohort study investigated the association between absolute count of NRBC on admission (day 1), the mean NRBC count between day 2 to 5, and outcome (mortality or the composite outcome of mortality and severe morbidity).

RESULTS

438 infants with a gestational age<32weeks and a birth weight<1500g were included within a five-year period, of whom 46 patients died and 65 suffered from severe morbidity. Nonsurvivors had significantly higher NRBC counts between day 2 and 5, as compared to survivors. This finding was observed in infants both appropriate and small for gestational age. An increase of 10/nL of the mean NRBC count on postnatal day 2 to 5 had an odds ratio for mortality of 6.95 (95% CI 2.21-21.86) and an odds ratio for the composite outcome mortality and severe morbidity of 3.43 (95% CI 1.43-8.24). The optimal cut-off value for prediction of death was NRBC >2/nL with a sensitivity of 85% and a specificity of 75%.

CONCLUSIONS

Elevation of NRBC on postnatal day 2 to 5 is an independent predictor of mortality in preterm infants.

Nucleated red blood cells impact DNA methylation and expression analyses of cord blood hematopoietic cells

BACKGROUND

Genome-wide DNA methylation (DNAm) studies have proven extremely useful to understand human hematopoiesis. Due to their active DNA content, nucleated red blood cells (nRBCs) contribute to epigenetic and transcriptomic studies derived from whole cord blood. Genomic studies of cord blood hematopoietic cells isolated by fluorescence-activated cell sorting (FACS) may be significantly altered by heterotopic interactions with nRBCs during conventional cell sorting.

RESULTS

We report that cord blood T cells, and to a lesser extent monocytes and B cells, physically engage with nRBCs during FACS. These heterotopic interactions resulted in significant cross-contamination of genome-wide epigenetic and transcriptomic data. Formal exclusion of erythroid lineage-specific markers yielded DNAm profiles (measured by the Illumina 450K array) of cord blood CD4 and CD8 T lymphocytes, B lymphocytes, natural killer (NK) cells, granulocytes, monocytes, and nRBCs that were more consistent with expected hematopoietic lineage relationships. Additionally, we identified eight highly differentially methylated CpG sites in nRBCs (false detection rate <5 %, |Δβ| >0.50) that can be used to detect nRBC contamination of purified hematopoietic cells or to assess the impact of nRBCs on whole cord blood DNAm profiles. Several of these erythroid markers are located in or near genes involved in erythropoiesis (ZFPM1, HDAC4) or immune function (MAP3K14, IFIT1B), reinforcing a possible immune regulatory role for nRBCs in early life.

CONCLUSIONS

Heterotopic interactions between erythroid cells and white blood cells can result in contaminated cell populations if not properly excluded during cell sorting. Cord blood nRBCs have a distinct DNAm profile that can significantly skew epigenetic studies. Our findings have major implications for the design and interpretation of genome-wide epigenetic and transcriptomic studies using human cord blood.

Immunologic and Hematological Abnormalities in Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a leading cause of mortality in preterm infants. This article reviews the immunologic and hematological abnormalities typically seen in infants with NEC, such as elevated plasma cytokine levels, thrombocytopenia, increased or decreased neutrophil counts, low monocyte counts, and anemia. Some of these findings may provide important diagnostic and prognostic information.

Fetal Erythroblastosis May Be an Indicator of Neonatal Transient Hyperinsulinism

BACKGROUND

Small for gestational age and birth asphyxia are associated with neonatal transient hyperinsulinism (THI). Some newborns with THI showed marked erythroblastosis on admission to our neonatal intensive care unit.

OBJECTIVE

This study was designed to test our hypothesis that fetal erythroblastosis may be a risk factor for developing THI.

METHODS

The records of all babies admitted to our neonatal intensive care unit within 24 h of birth between January 2010 and May 2014, and who were born after 34 weeks of gestation, were retrospectively reviewed. Hyperinsulinism was diagnosed as hypoglycemia concomitant with high serum insulin in babies requiring >6 mg/kg/min intravenous glucose and THI as hyperinsulinism without maternal diabetes or genetic disorders. The following three possible risk factors for THI were evaluated: (1) birth weight z-score, (2) 1-min Apgar score and (3) absolute nucleated red blood cell (aNRBC) count on admission.

RESULTS

Of 705 infants, 8 were diagnosed with THI. Multivariate logistic regression analysis revealed that the aNRBC count was the most significant risk factor for THI. The median aNRBC count was 181/µl (interquartile range 0-538/µl), and 8 of 71 infants (11.3%) having an aNRBC count >1,413/µl (90th percentile in this study) had THI. The aNRBC counts in the 8 cases with THI were significantly higher than those in the 5 cases with hyperinsulinism caused by maternal diabetes or genetic disorders.

CONCLUSIONS

This study showed that the aNRBC count was strongly associated with subsequent THI. Fetal erythroblastosis, characterized by chronic fetal hypoxia, may be an indicator of perinatal stress sufficient to cause THI.

Estimating the nucleated red blood cell 'emergence time' in neonates

OBJECTIVE

The time between onset of fetal hypoxia and first appearance of nucleated red blood cells (NRBCs) in the blood can conceptually be divided into two periods; (1) the 'erythropoietin (EPO) generation time', which previous fetal studies suggest is 4 to 5 h, and (2) the 'NRBC emergence time'. In this study, we estimated the latter as the time required for NRBC to appear in the blood after administering a dose of recombinant EPO.

STUDY DESIGN

This was a retrospective analysis of data from a multihospital healthcare system (Intermountain Healthcare). Data were included only for neonates born ≥34 weeks gestation between the dates 1 January 2005 and 31 October 2012 and only if they received a dose of darbepoetin during their neonatal intensive care unit stay and had one or more complete blood cell counts (CBCs) obtained during the 3-day period before the dose was given and one or more CBCs in the 7-day period after the dose.

RESULT

The study involved 31 neonates who received 34 doses of darbepoetin. Seven doses were 4 μg kg(-1) and twenty-seven doses were 10 μg kg(-1). Twenty-six CBCs were obtained during the 24-h period following the darbepoetin dose and none had NRBC identified. NRBC first appeared in the blood between 24 and 36 h after the dose. Recipients of the higher dose generally had a higher peak NRBC count but the NRBC 'emergence time' did not appear to depend on dose.

CONCLUSION

Following fetal hypoxia, transcription and translation of the EPO gene result in an elevation in plasma EPO concentration. Previous fetal studies suggest this process requires 4 to 5 h. The present studies suggest that, following the increase in plasma EPO, NRBC emerge into the circulation in ≥24 h. If this model serves as a reasonable estimate, it suggests that neonates with an elevated NRBC count at birth had the onset of hypoxia at least 28 to 29 h before birth.

Haematological abnormalities in neonatal necrotizing enterocolitis

OBJECTIVE

Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality in preterm infants born prior to 32 weeks gestation or with a birth weight less than 1500 grams. In this article, we review hematological abnormalities associated with NEC.

METHODS

A literature search was performed using the databases PubMed, EMBASE, and Scopus, and the electronic archive of abstracts presented at the annual meetings of the Pediatric Academic Societies.

RESULTS

Thrombocytopenia, disseminated intravascular coagulation, increased or decreased neutrophil counts, and hemolytic anemia are frequent events in NEC.

CONCLUSIONS

NEC is associated with several hematological abnormalities, which may play a direct or indirect role in the pathogenesis of gut mucosal injury, and may also carry important prognostic information.

Hematologic profile of the fetus with systemic inflammatory response syndrome

OBJECTIVE

The fetal inflammatory response syndrome (FIRS) is associated with impending onset of preterm labor/delivery, microbial invasion of the amniotic cavity and increased perinatal morbidity. FIRS has been defined by an elevated fetal plasma interleukin (IL)-6, a cytokine with potent effects on the differentiation and proliferation of hematopoietic precursors. The objective of this study was to characterize the hematologic profile of fetuses with FIRS.

STUDY DESIGN

Fetal blood sampling was performed in patients with preterm prelabor rupture of membranes and preterm labor with intact membranes (n=152). A fetal plasma IL-6 concentration ≥ 11 pg/mL was used to define FIRS. Hemoglobin concentration, platelet count, total white blood cell (WBC) count, differential count, and nucleated red blood cell (NRBC) count were obtained. Since blood cell count varies with gestational age, the observed values were corrected for fetal age by calculating a ratio between the observed and expected mean value for gestational age.

RESULTS

1) The prevalence of FIRS was 28.9% (44/152); 2) fetuses with FIRS had a higher median corrected WBC and corrected neutrophil count than those without FIRS (WBC: median 1.4, range 0.3-5.6, vs. median 1.1, range 0.4-2.9, P=0.001; neutrophils: median 3.6, range 0.1-57.5, vs. median 1.8, range 0.2-13.9, P<0.001); 3) neutrophilia (defined as a neutrophil count >95th centile of gestational age) was significantly more common in fetuses with FIRS than in those without FIRS (71%, 30/42, vs. 35%, 37/105; P<0.001); 4) more than two-thirds of fetuses with FIRS had neutrophilia, whereas neutropenia was present in only 4.8% (2/42); 5) FIRS was not associated with detectable changes in hemoglobin concentration, platelet, lymphocyte, monocyte, basophil or eosinophil counts; and 6) fetuses with FIRS had a median corrected NRBC count higher than those without FIRS. However, the difference did not reach statistical significance (NRBC median 0.07, range 0-1.3, vs. median 0.04, range 0-2.3, P=0.06).

CONCLUSION

The hematologic profile of the human fetus with FIRS is characterized by significant changes in the total WBC and neutrophil counts. The NRBC count in fetuses with FIRS tends to be higher than fetuses without FIRS.

A study on the measurement of the nucleated red blood cell (nRBC) count based on birth weight and its correlation with perinatal prognosis in infants with very low birth weights

Purpose

The aim of this study was conducted to investigate the mean nRBC count in very low births weight infants (VLBWIs) and to determine the usefulness of the nRBC as an independent prognostic factors of perinatal complications in VLBWIs.

Methods

This study was conducted on 112 VLBWIs who were hospitalized in the neonatal intensive care unit (NICU) of the author's hospital within the period from March 2003 to and May 2008. Based on the infants' nucleated red blood cells (nRBC) counts at birth, on the third day after birth, on the seventh day after birth, in the second week after birth, and in the fourth week after birth in the medical records, the correlation between nRBC or absolute nRBC counts with birth weight, gestational age, and other perinatal outcomes were retrospectively investigated.

Results

In VLBWIs, their mean nRBC and absolute nRBC counts were showing a gradual decrease after birth, and they were consisteantly kept at low values since one week after and inversely proportional to the birth weights. The mean nRBC counts based on the stage after birth showed a significant correlation with perinatal death, necrotizing enterocolitis, and severe intraventricular hemorrhage.

Conclusion

The increase in the nRBC count showed a significant correlation with having a severe intraventricular hemorrhage, necrotizing enterocolitis, and perinatal death in VLBWIs. If an increase or no decrease in the nRBC count after birth is observed, newborn-infant care precautions should be required.

Response of leukocytes and nucleated red blood cells in very low-birth weight preterm infants after exposure to intrauterine inflammation

OBJECTIVES

To test the hypothesis if very immature preterm infants exposed to chorioamnionitis would exhibit increased numbers of leukocytes, neutrophils, and nucleated red blood cells (NRBC) in peripheral blood.

STUDY DESIGN

Preterm infants with birth weight <1500 g were prospectively evaluated. Blood cells were counted within the first hour of life in infants exposed to histological chorioamnionitis and controls.

RESULTS

Birth weight, gestational age, and sex did not differ between the groups (n = 71). Seventeen infants who were exposed to chorioamnionitis had significantly higher counts of leukocytes, neutrophils, and immature neutrophils after birth. However, there was no difference in the number of circulating NRBCs between both groups. In contrast, there was a tendency towards an increased NRBC count in the control group.

CONCLUSION

Preterm infants exposed to chorioamnionitis elicited a strong inflammatory response as reflected by increased numbers of leukocytes and neutrophils. However, chorioamnionitis did not induce an increase in numbers of NRBC.

Inflammation-induced preterm birth in a murine model is associated with increases in fetal macrophages and circulating erythroid precursors

The presence of intrauterine inflammation has been associated with adverse neurologic outcomes in preterm infants, but the precise mechanisms of fetal brain injury remain unclear. We sought to evaluate inflammatory cell trafficking, fetal organ damage, and molecular regulation in the fetoplacental unit using an established mouse model of preterm birth associated with intrauterine inflammation. Gestational sacs were harvested 6 hours after intrauterine infusion of saline or lipopolysaccharide (LPS). Histologic, immunohistochemical, and molecular investigations were performed to identify target organ damage and the cellular phenotype of inflammatory cells and to quantify circulating inflammatory and hematopoietic mediators within the placental and fetal tissue. There was widespread increase in fetal macrophages in LPS-exposed pups, including within the leptomeninges of the brain, associated with significantly higher of interleukin 6 levels in LPS-exposed pups. Although no specific central nervous system injury (necrosis or apoptosis) was documented, liver hematomas were seen significantly more frequently in LPS-exposed pups. Circulating nucleated fetal erythrocytes were also present more frequently with LPS exposure without significantly higher erythropoietin levels than saline-exposed mice. The presence of increased macrophages, increased circulating interleukin 6 levels, and increased circulating erythroid precursors in LPS-exposed pups suggests that these are significant factors associated with potential target organ damage, such as liver hematomas, associated with intrauterine inflammation and preterm birth. The role of macrophages within the fetal leptomeninges is unclear, but they may play an important role in inflammatory-mediated brain damage, and further investigation of their significance and potential as therapeutic targets is warranted.