Serum neutrophil gelatinase-associated lipocalin as a predictor of the development of bronchopulmonary dysplasia in preterm infants

Proteomics identifies lipocalin-2 in neonatal inflammation associated with cerebrovascular alteration in mice and preterm infants

Staphylococcus (S.) epidermidis is the most common nosocomial coagulase-negative staphylococci infection in preterm infants. Clinical signs of infection are often unspecific and novel markers to complement diagnosis are needed. We investigated proteomic alterations in mouse brain after S. epidermidis infection and in preterm infant blood. We identified lipocalin-2 (LCN2) as a crucial protein associated with cerebrovascular changes and astrocyte reactivity in mice. We further proved that LCN2 protein expression was associated with endothelial cells but not astrocyte reactivity. By combining network analysis and differential expression approaches, we identified LCN2 linked to blood C-reactive protein levels in preterm infants born <28 weeks of gestation. Blood LCN2 levels were associated with similar alterations of cytokines and chemokines in both infected mice and human preterm infants with increased levels of C-reactive protein. This experimental and clinical study suggests that LCN2 may be a marker of preterm infection/inflammation associated with cerebrovascular changes and neuroinflammation.

The eNAMPT/TLR4 inflammatory cascade drives the severity of intra-amniotic inflammation in pregnancy and predicts infant outcomes

Introduction: Intra-amniotic inflammation (IAI) or chorioamnionitis is a common complication of pregnancy producing significant maternal morbidity/mortality, premature birth and neonatal risk of chronic lung diseases such as bronchopulmonary dysplasia (BPD). We examined eNAMPT (extracellular nicotinamide phosphoribosyltransferase), a critical inflammatory DAMP and TLR4 ligand, as a potential therapeutic target to reduce IAI severity and improve adverse fetal/neonatal outcomes. Methods: Blood/tissue samples were examined in: 1) women with histologically-proven chorioamnionitis, 2) very low birth weight (VLBW) neonates, and 3) a preclinical murine pregnancy model of IAI. Groups of pregnant IAI-exposed mice and pups were treated with an eNAMPT-neutralizing mAb. Results: Human placentas from women with histologically-proven chorioamnionitis exhibited dramatic NAMPT expression compared to placentas without chorioamnionitis. Increased NAMPT expression in whole blood from VLBW neonates (day 5) significantly predicted BPD development. Compared to untreated LPS-challenged murine dams (gestational day 15), pups born to eNAMPT mAb-treated dams (gestational days 15/16) exhibited a > 3-fold improved survival, reduced neonate lung eNAMPT/cytokine levels, and reduced development and severity of BPD and pulmonary hypertension (PH) following postnatal exposure to 100% hyperoxia days 1-14. Genome-wide gene expression studies of maternal uterine and neonatal cardiac tissues corroborated eNAMPT mAb-induced reductions in inflammatory pathway genes. Discussion: The eNAMPT/TLR4 inflammatory pathway is a highly druggable contributor to IAI pathobiology during pregnancy with the eNAMPT-neutralizing mAb a novel therapeutic strategy to decrease premature delivery and improve short- and long-term neonatal outcomes. eNAMPT blood expression is a potential biomarker for early prediction of chronic lung disease among premature neonates.

Control variables of serum ferritin concentrations in hospitalized newborn infants: an observational study

Both iron excess and deficiency are deleterious to cellular and organ homeostasis. Serum ferritin levels serve as a biomarker of iron storage; however, their distribution and determinants in sick newborn infants remain unclear. This study aimed to investigate the reference range and independent variables of serum ferritin in hospitalized newborn infants. All newborn infants who were hospitalized at a tertiary neonatal center within 24 h of birth were retrospectively reviewed for the period of April 2015 through March 2017. Serum ferritin levels were assessed using venous blood samples obtained at admission and their independent variables were explored. The study population comprised 368 infants (36.2 ± 2.8 weeks gestation and 2319 ± 623 g at birth), whose median serum ferritin level was 149 µg/L (inter-quartile range: 81-236). The multivariable model used to explain serum ferritin values comprised hemoglobin, lactate dehydrogenase, blood pH, and maternal hypertensive disorders in pregnancy (all p < 0.01, adjusted for sex and birth weight). Serum ferritin values in hospitalized newborn infants were comparable to those previously reported using umbilical cord blood. Our novel findings indicated the association between blood pH, lactate dehydrogenase, and ferritin levels, suggesting the influence of antenatal hypoxia-ischemia and stress to serum ferritin levels.

Role of Systemic Inflammatory Indices in the Prediction of Moderate to Severe Bronchopulmonary Dysplasia in Preterm Infants

INTRODUCTION

The role of systemic inflammatory indices in the diagnosis of bronchopulmonary dysplasia (BPD) is unknown. The aim of the study was to determine the possible clinical utility of systemic inflammatory indices in the prediction of moderate to severe BPD.

METHODS

Premature infants<32 weeks of gestational age were included in the study. Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), systemic immune-inflammation index (SII), pan-immune-inflammation value (PIV), and systemic inflammation response index (SIRI) were calculated at birth and at the time of diagnosis of BPD (at 36th weeks of postmenstrual age). The patients were divided into two groups as no or mild BPD and moderate or severe BPD.

RESULTS

A total of 1146 infants were included in the study, 957 in Group 1 and 189 in Group 2. The SIRI value was significantly higher in moderate or severe BPD both at birth and at the 36th week of postmenstrual age (p<0.001 and p<0.001, respectively). The AUC value of SIRI was 0.809 and the cut-off value was>0.98 in the predictivity of BPD at birth. The AUC value of SIRI was 0.842 and the cut-off value was>1.33 for the diagnosis of BPD at 36th week of postmenstrual age. After multiple logistic regression analysis, SIRI was shown to be a significant parameter for the diagnosis of BPD (OR 2.847, 95% CI 1.557-4.875).

CONCLUSIONS

SIRI may be a useful biomarker for predicting moderate to severe BPD and a marker of clinical importance in the follow-up of infants with BPD.

Placental Neutrophil Infiltration Associated with Tobacco Exposure but Not Development of Bronchopulmonary Dysplasia

Objective: In utero inflammation is associated with bronchopulmonary dysplasia (BPD) in preterm infants. We hypothesized that maternal tobacco exposure (TE) might induce placental neutrophil infiltration, increasing the risk for BPD. Study design: We compared the composite outcome of BPD and death in a prospective pilot study of TE and no-TE mothers and their infants born <32 weeks. Placental neutrophil infiltration was approximated by neutrophil gelatinase-associated lipocalin (NGAL) ELISA, and total RNA expression was analyzed via NanoString© (Seattle, WA, USA). Result: Of 39 enrolled patients, 44% were classified as tobacco exposure. No significant difference was noted in the infant’s composite outcome of BPD or death based on maternal tobacco exposure. NGAL was higher in placentas of TE vs. non-TE mothers (p < 0.05). Placental RNA analysis identified the upregulation of key inflammatory genes associated with maternal tobacco exposure. Conclusion: Tobacco exposure during pregnancy was associated with increased placental neutrophil markers and upregulated inflammatory gene expression. These findings were not associated with BPD.

Management of Acute Kidney Injury in Extremely Low Birth Weight Infants

Acute kidney injury (AKI) is a common problem in the neonatal intensive care unit (NICU). Neonates born at <1,000 g (extremely low birth weight, ELBW) are at an increased risk of secondary associated comorbidities such as intrauterine growth restriction, prematurity, volume restriction, ischaemic injury, among others. Studies estimate up to 50% ELBW infants experience at least one episode of AKI during their NICU stay. Although no curative treatment for AKI currently exists, recognition is vital to reduce potential ongoing injury and mitigate long-term consequences of AKI. However, the definition of AKI is imperfect in this population and presents clinical challenges to correct identification, thus contributing to under recognition and reporting. Additionally, the absence of guidelines for the management of AKI in ELBW infants has led to variations in practice. This review summarizes AKI in the ELBW infant and includes suggestions such as close observation of daily fluid balance, review of medications to reduce nephrotoxic exposure, management of electrolytes, maximizing nutrition, and the use of diuretics and/or dialysis when appropriate.

Single cell transcriptomic analysis of murine lung development on hyperoxia-induced damage

During late lung development, alveolar and microvascular development is finalized to enable sufficient gas exchange. Impaired late lung development manifests as bronchopulmonary dysplasia (BPD) in preterm infants. Single-cell RNA sequencing (scRNA-seq) allows for assessment of complex cellular dynamics during biological processes, such as development. Here, we use MULTI-seq to generate scRNA-seq profiles of over 66,000 cells from 36 mice during normal or impaired lung development secondary to hyperoxia with validation of some of the findings in lungs from BPD patients. We observe dynamic populations of cells, including several rare cell types and putative progenitors. Hyperoxia exposure, which mimics the BPD phenotype, alters the composition of all cellular compartments, particularly alveolar epithelium, stromal fibroblasts, capillary endothelium and macrophage populations. Pathway analysis and predicted dynamic cellular crosstalk suggest inflammatory signaling as the main driver of hyperoxia-induced changes. Our data provides a single-cell view of cellular changes associated with late lung development in health and disease.

High Neutrophil-to-Lymphocyte Ratio Is an Early Predictor of Bronchopulmonary Dysplasia

Background and Objective: Bronchopulmonary dysplasia (BPD) is a common complication in preterm infants; predicting the degree of BPD at an early life stage is difficult. Inflammation is a crucial risk factor for BPD pathogenesis, and the neutrophil-to-lymphocyte ratio (NLR) is a potential systemic inflammatory biomarker. We aimed to assess the predictive value of the NLR for BPD. Methods: We carried out a retrospective, single-center, observational study of neonates with gestational ages (GAs) <32 weeks and assessed the association between the NLR and BPD. Results: The study population included 296 preterm infants with BPD (n = 144) or without BPD (n = 152). Among the infants, 75 (25.3%) had mild BPD, 37 (12.5%) had moderate BPD, and 32 (10.8%) had severe BPD. The BPD group had a higher NLR at birth and at 72 h than the non-BPD group. The NLR cutoff value at 72 h for the prediction of BPD was 3.035 (sensitivity = 0.519, specificity = 0.964), and the area under the curve (AUC) was 0.714. The NLR cutoff value at 72 h for predicting severe BPD was 3.105 (sensitivity = 0.607, specificity = 0.819), with an AUC of 0.756. At the NLR cutoff value at 72 for the prediction of BPD, the AUCs were 0.640 and 0.970 in the preterm infants with EOS and congenital pneumonia, respectively. Conclusions: The NLR is an inexpensive, accessible and convenient tool; an increase in the NLR at 72 h could be an early predictor of BPD, especially severe BPD. Additionally, the NLR at 72 h could be a predictor of BPD in preterm infants with intrauterine infections.

Effect of perinatal risk factors on neutrophil gelatinase-associated lipocalin (NGAL) level in umbilical and peripheral blood in neonates

Introduction

Acute kidney injury biomarkers are opening a new era in diagnosing kidney failure. The requirement for a specific and sensitive marker of kidney function is highly desirable in neonates because the diagnostic possibilities in this age group are not sufficient. Recent research show that neutrophil gelatinase-associated lipocalin (NGAL) can have a great potential but there is a wide range of medical conditions, that may influence their expression.

The aim of the study

was to evaluate the impact of perinatal risk factors on NGAL level in neonates.

Material and methods

NGAL was measured in umbilical cord blood and peripheral blood in full term neonates with perinatal risk factors during the first days of life.

Results

We found significantly higher umbilical cord blood NGAL levels in neonates with perinatal risk factors (117.69 ng/ml) compared to the control group (64.37 ng/ml). No significant difference in peripheral blood NGAL level was shown between the two groups. Umbilical cord blood NGAL level correlated positively with peripheral blood NGAL level (r = 0.36, p < 0.01). Umbilical cord blood NGAL level was significantly higher in neonates with fetal distress and infection compared to neonates with other perinatal risk factors. Peripheral blood NGAL level was significantly higher in neonates with infection compared to neonates with other perinatal risk factors. Significantly higher umbilical cord blood NGAL levels were seen in neonates born by operative delivery compared to born by natural delivery.

An Elevation of Serum Ferritin Level Might Increase Clinical Risk for the Persistence of Patent Ductus Arteriosus, Sepsis and Bronchopulmonary Dysplasia in Erythropoietin-Treated Very-Low-Birth-Weight Infants

BACKGROUND

The substantial risk of iron overload is not routinely monitored in most of the neonatal intensive care units (NICUs) in Japan; however, blood transfusion is an essential strategy for successfully treating preterm low-birth-weight infants.

OBJECTIVE

The aim of this study was to investigate the iron status and clinical features of infants with a birth weight of <1,500 g, i.e. very-low-birth-weight infants (VLBWIs).

METHODS

This prospective observational study enrolled 176 (82.6%) patients from a total of 213 VLBWIs admitted to our NICU from 2009 to 2014. Clinical information was collected including maternal records and infant morbidity and treatment. Management strategies including enteral iron supplementation, erythropoietin administration and blood transfusion were allowed according to the consensus in Japan. The hematological status was surveyed from birth to 12 postnatal weeks of age. The iron status was determined according to serum iron, unbound iron-binding capacity and serum ferritin. The definition of hyperferritinemia was set as a value of ≥500 ng/ml.

RESULTS

Twenty-four (13.6%) infants displayed hyperferritinemia. A multiple logistic analysis selected 3 associated factors of hyperferritinemia: surgical ligation for patent ductus arteriosus, sepsis and moderate or severe states of bronchopulmonary dysplasia. We also verified that the value of ferritin was significantly correlated with those of aspartate transaminase, creatine kinase and C-reactive protein according to a multilinear regression analysis. After excluding the ferritin data of these outliers, we did not observe any factors associated with hyperferritinemia.

CONCLUSIONS

Hyperferritinemia might be associated with oxygen radical diseases and susceptibility to infection.

Urinary neutrophil gelatinase-associated lipocalin is an early predictor of acute kidney injury in premature infants

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) is produced in response to tubular epithelial injury and is a biomarker of tubulointerstitial injury. The aim of the present study was to examine whether acute kidney injury (AKI) could be predicted by measuring uNGAL in very low-birth weight (VLBW) infants. Forty VLBW infants with birthweight below 1,500 g were enrolled in the present study. uNGAL and serum creatinine (sCre) were measured daily from postnatal days 0 to 8. Infants with sCre ≥1.2 mg/dl were diagnosed with AKI. The relationship of uNGAL with sCre was measured on the day after uNGAL measurement (next-day sCre) was examined. The results showed that 16 infants had sCre ≥1.2 mg/dl in this period. Logistic regression analysis revealed that uNGAL on postnatal days 2, 3, 4, 5 and 6 was correlated with next-day sCre (P<0.05). uNGAL corrected by urinary Cre (uCre) (uNGAL/uCre) was only correlated with an increase in next-day sCre on postnatal days 5 and 6 (P<0.05). For the logistic analysis, subjects with high and low uNGAL levels based on the median value for each day, uNGAL on postnatal days 2, 3 and 6 in the high uNGAL group was correlated with an increase in next-day sCre. Thus, AKI may be predicted by measuring uNGAL in VLBW infants. This measurement was non-invasive, and is potentially useful for the evaluation of renal function in VLBW infants.

Urinary Neutrophil Gelatinase-Associated Lipocalin Levels in Neonates

BACKGROUND

Acute kidney injury (AKI) is common in preterm infants and is associated with high mortality and morbidity. New biomarkers for the early detection of AKI have been identified. Specifically, urinary neutrophil gelatinase-associated lipocalin (uNGAL) is a new and powerful biomarker for AKI and sepsis. Our study evaluated the reference range of uNGAL in healthy neonates in Taiwan.

METHODS

This study examined 24 preterm and 38 term infants without clinical complications. Urine samples were collected and the uNGAL values were measured at postnatal age (PNA) 3 days, 7 days, 14 days, and 21 days in the preterm infants and at PNA 3 days in the term infants. The uNGAL values were tested using enzyme-linked immunosorbent assay.

RESULTS

The median uNGAL values in the preterm infants at PNA 3 days, 7 days, 14 days, and 21 days were 41.52 ng/mL, 35.82 ng/mL, 43.79 ng/mL, and 30.85 ng/mL, respectively. The median value at PNA 3 days in the term infants was 88.1 ng/mL. No significant differences associated with gestational age, birth body weight, or PNA were observed among the preterm infants. However, the uNGAL values in the female term infants were higher than those in the male term infants (p = 0.003).

CONCLUSION

This study presents preliminary data on uNGAL levels in neonates in Taiwan. A large-scale study investigating the correlations between uNGAL and with gestational age, birth body weight, sex, and PNA is recommended.

Biomarkers for Bronchopulmonary Dysplasia in the Preterm Infant

Bronchopulmonary dysplasia (BPD) is a chronic inflammatory lung disease of very-low-birth-weight (VLBW) preterm infants, associated with arrested lung development and a need for supplemental oxygen. Over the past few decades, the incidence of BPD has significantly raised as a result of improved survival of VLBW infants requiring mechanical ventilation. While early disease detection is critical to prevent chronic lung remodeling and complications later in life, BPD is often difficult to diagnose and prevent due to the lack of good biomarkers for identification of infants at risk, and overlapping symptoms with other diseases, such as pulmonary hypertension (PH). Due to the current lack of effective treatment available for BPD and PH, research is currently focused on primary prevention strategies, and identification of biomarkers for early diagnosis, that could also represent potential therapeutic targets. In addition, novel histopathological, biochemical, and molecular factors have been identified in the lung tissue and in biological fluids of BPD and PH patients that could associate with the disease phenotype. In this review, we provide an overview of biomarkers for pediatric BPD and PH that have been identified in clinical studies using various biological fluids. We also present a brief summary of the information available on current strategies and guidelines to prevent and diagnose BPD and PH, as well as their pathophysiology, risk factors, and experimental therapies currently available.

Gene expression profile in newborn rat lungs after two days of recovery of mechanical ventilation

BACKGROUND

Preterm infants having immature lungs often require respiratory support, potentially leading to bronchopulmonary dysplasia (BPD). Conventional BPD rodent models based on mechanical ventilation (MV) present outcome measured at the end of the ventilation period. A reversible intubation and ventilation model in newborn rats recently allowed discovering that different sets of genes modified their expression related to time after MV. In a newborn rat model, the expression profile 48 h after MV was analyzed with gene arrays to detect potentially interesting candidates with an impact on BPD development.

METHODS

Rat pups were injected P4-5 with 2 mg/kg lipopolysaccharide (LPS). One day later, MV with 21 or 60% oxygen was applied during 6 h. Animals were sacrified 48 h after end of ventilation. Affymetrix gene arrays assessed the total gene expression profile in lung tissue.

RESULTS

In fully treated animals (LPS + MV + 60% O(2)) vs. controls, 271 genes changed expression significantly. All modified genes could be classified in six pathways: tissue remodeling/wound repair, immune system and inflammatory response, hematopoiesis, vasodilatation, and oxidative stress. Major alterations were found in the MMP and complement system.

CONCLUSION

MMPs and complement factors play a central role in several of the pathways identified and may represent interesting targets for BPD treatment/prevention.Bronchopulmonary dysplasia (BPD) is a chronic lung disease occurring in ~30% of preterm infants born less than 30 wk of gestation (1). Its main risk factors include lung immaturity due to preterm delivery, mechanical ventilation (MV), oxygen toxicity, chorioamnionitis, and sepsis. The main feature is an arrest of alveolar and capillary formation (2). Models trying to decipher genes involved in the pathophysiology of BPD are mainly based on MV and oxygen application to young mammals with immature lungs of different species (3). In newborn rodent models, analyses of lung structure and gene and protein expression are performed for practical reasons directly at the end of MV (4,5,6). However, later appearing changes of gene expression might also have an impact on lung development and the evolution towards BPD and cannot be discovered by such models. Recently, we developed a newborn rat model of MV using an atraumatic (orotracheal) intubation technique that allows the weaning of the newborn animal off anesthesia and MV, the extubation to spontaneous breathing, and therefore allows the evaluation of effects of MV after a ventilation-free period of recovery (7). Indeed, applying this concept of atraumatic intubation by direct laryngoscopy, we recently were able to show significant differences between gene expression changes appearing directly after MV compared to those measured after a ventilation-free interval of 48 h. Immediately after MV, inflammation-related genes showed a transitory modified expression, while another set of more structurally related genes changed their expression only after a delay of 2 d (7). Lung structure, analyzed by conventional 2D histology and also by 3D reconstruction using synchrotron x-ray tomographic microscopy revealed, 48 h after end of MV, a reduced complexity of lung architecture compared to the nonventilated rat lungs, similar to the typical findings in BPD. To extend these observations about late gene expression modifications, we performed with a similar model a full gene expression profile of lung tissue 48 h after the end of MV with either room air or 60% oxygen. Essentially, we measured changes in the expression of genes related to the MMPs and complement system which played a role in many of the six identified mostly affected pathways.

Affect of Early Life Oxygen Exposure on Proper Lung Development and Response to Respiratory Viral Infections

Children born preterm often exhibit reduced lung function and increased severity of response to respiratory viruses, suggesting that premature birth has compromised proper development of the respiratory epithelium and innate immune defenses. Increasing evidence suggests that premature birth promotes aberrant lung development likely due to the neonatal oxygen transition occurring before pulmonary development has matured. Given that preterm infants are born at a point of time where their immune system is also still developing, early life oxygen exposure may also be disrupting proper development of innate immunity. Here, we review current literature in hopes of stimulating research that enhances understanding of how the oxygen environment at birth influences lung development and host defense. This knowledge may help identify those children at risk for disease and ideally culminate in the development of novel therapies that improve their health.

Serum and urinary NGAL in septic newborns

Neutrophil gelatinase-associated lipocalin (NGAL) is postulated to be a potentially new and highly specific/sensitive marker of acute kidney injury (AKI). The aim of this study was to assess the impact of inflammation on serum and urine NGAL in newborns that were treated due to infection. We determined serum and urine NGAL concentrations in 73 infants (51 with sepsis; 22 with severe sepsis) admitted to the Intensive Care Unit in the first month of life, for three consecutive days during the course of treatment for infection. 29 neonates without infection served as the control group. Septic patients, in particular, severe sepsis patients, had increased serum and urinary NGAL levels in the three subsequent days of observation. Five septic patients who developed AKI had elevated serum and urinary NGAL values to a similar extent as septic neonates without AKI. A strong correlation was found between the concentration of serum and urinary NGAL and inflammatory markers, such as CRP and procalcitonin. Serum and urinary NGAL levels were also significantly associated with NTISS (neonatal therapeutic intervention scoring system) values. We conclude that increased serum and urinary NGAL values are not solely a marker of AKI, and more accurately reflect the severity of inflammatory status.

Early biomarkers as predictors for bronchopulmonary dysplasia in preterm infants: a systematic review

BACKGROUND

Bronchopulmonary dysplasia (BPD) is usually diagnosed in preterm infants at least 28 days after birth. Great interest lies in the potential to identify biomarkers that predict development of the disease and future neurodevelopmental outcomes. We have reviewed the existing literature on early biomarkers as predictors for BPD in preterm infants.

METHODS

Two reviewers independently searched the databases of PubMed, EMBASE, and Google Scholar for studies pertaining to biomarkers for BPD. Studies were assessed using Quality Assessment of Diagnostic Accuracy Studies criteria.

RESULTS

We identified 46 relevant articles that are summarized in the review. These studies assessed over 30 potential biomarkers. Sensitivity and specificity of biomarkers were reported or could be calculated for only 16 articles, and ranged from 0 to 100 %. Based on the nine highest quality studies, serum KL-6, CC16, neutrophil gelatinase-associated lipocalin, and end-tidal carbon monoxide (etCO) perform extremely well in predicting the early diagnosis of established BPD, highlighting these biomarkers as promising candidates for future research.

CONCLUSIONS

Published data from studies on serum biomarkers and etCO suggest that biomarkers may have great potential to predict the subsequent BPD and neurodevelopmental outcomes. These biomarkers need validation in larger studies, and the generalizability of biomarkers for predicting BPD, as well as the neurodevelopmental outcomes, needs to be further explored.