Blood cytokines during the perinatal period in very preterm infants: relationship of inflammatory response and bronchopulmonary dysplasia

Nitric oxide regulation of fetal and newborn lung development and function

In the developing lung, nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) signaling are essential in regulating lung formation and vascular tone. Animal studies have linked many anatomical and pathophysiological features of newborn lung disease to abnormalities in the NO/cGMP signaling system. They have demonstrated that driving this system with agonists and antagonists alleviates many of them. This research has spurred the rapid clinical development, testing, and application of several NO/cGMP-targeting therapies with the hope of treating and potentially preventing significant pediatric lung diseases. However, there are instances when the therapeutic effectiveness of these agents is limited. Studies indicate that injury-induced disruption of several critical components within the signaling system may hinder the promise of some of these therapies. Recent research has identified basic mechanisms that suppress NO/cGMP signaling in the injured newborn lung. They have also pinpointed biomarkers that offer insight into the activation of these pathogenic mechanisms and their influence on the NO/cGMP signaling system's integrity in vivo. Together, these will guide the development of new therapies to protect NO/cGMP signaling and safeguard newborn lung development and function. This review summarizes the important role of the NO/cGMP signaling system in regulating pulmonary development and function and our evolving understanding of how it is disrupted by newborn lung injury.

The role of nutritional interventions in the prevention and treatment of chronic lung disease of prematurity

Chronic lung disease of prematurity or bronchopulmonary dysplasia (BPD) is a common complication of preterm birth. Nutrition may affect incidence and severity of BPD. In this context, the Section on Nutrition, Gastroenterology and Metabolism, the Pulmonary Section of the European Society for Paediatric Research (ESPR) and SPR have joined forces to review the current knowledge on nutritional issues related to BPD. The aim of this narrative review is to discuss the clinical implications for nutritional practice. Nutrient deficiencies may influence pathogenesis of BPD. Adequate nutrition and growth can play a crucial role in the prevention of and recovery from BPD. Optimal nutrition strategy is an important principle, especially in the early postnatal period. As optimal energy intake in infants at risk of BPD or with evolving BPD is not yet defined, further research with well-designed studies on nutritional strategies for preterm infants with BPD is urgently needed. IMPACT: Based on current evidence it seems reasonable to recommend that BPD diagnosed infants should receive an energy supply ranging from 120 to 150 Kcal/kg/d. Exclusive MOM feed with adequate fortification should be encouraged as this is associated with a significant reduction in the risk of BPD. Suboptimal nutritional delivery is often seen in preterm infants with BPD compared to controls.

Outcomes at 7 Years of Age of Former Very Preterm Neonates with Repeated Surfactant Treatment for Prolonged Respiratory Distress in the Neonatal Period

This study aimed at evaluating the 7-year outcomes of 118 very preterm newborns (VPNs, gestational age = 26 ± 1.4 w) involved in a randomized controlled trial. They presented neonatal respiratory distress (RDS), requiring ventilation for 14 ± 2 days post-natal age (PNA). A repeated instillation of 200 mg/kg poractant alfa (SURF) did not improve early bronchopulmonary dysplasia, but the SURF infants needed less re-hospitalization than the controls for respiratory problems at 1- and 2-year PNA. There was no growth difference at 7.1 ± 0.3 years between 41 SURF infants and 36 controls (80% of the eligible children), and 7.9% SURF infants vs. 28.6% controls presented asthma (p = 0.021). The children underwent cognitive assessment (WISC IV) and pulmonary function testing (PFT), measuring their spirometry, lung volume, and airway resistance. The spirometry measures showed differences (p < 0.05) between the SURF infants and the controls (mean ± standard deviation (median z-score)) for FEV1 (L/s) (1.188 ± 0.690(-0.803) vs. 1.080 ± 0.243 (-1.446)); FEV1 after betamimetics (1.244 ± 0.183(-0.525) vs. 1.091 ± 0.20(-1.342)); FVC (L) (1.402 ± 0.217 (-0.406) vs. 1.265 ± 0.267 (-1.141)), and FVC after betamimetics (1.452 ± 0.237 (-0.241) vs. 1.279 ± 0.264 (-1.020)). PFT showed no differences in the volumes or airway resistance. The global IQ median (interquartile range) was 89 (82:99) vs. 89 (76:98), with 61% of the children >85 in both groups. Repeated surfactant treatment in VPNs presenting severe RDS led to the attenuation of early lung injuries, with an impact on long-term pulmonary sequelae, without differences in neurodevelopmental outcomes.

Quercetin supplementation attenuates airway hyperreactivity and restores airway relaxation in rat pups exposed to hyperoxia

Hyperoxia exposure of immature lungs contributes to lung injury and airway hyperreactivity. Up to now, treatments of airway hyperreactivity induced by hyperoxia exposure have been ineffective. The aim of this study was to investigate the effects of quercetin on hyperoxia-induced airway hyperreactivity, impaired relaxation, and lung inflammation. Newborn rats were exposed to hyperoxia (FiO2 > 95%) or ambient air (AA) for seven days. Subgroups were injected with quercetin (10 mg·kg-1·day-1). After exposures, tracheal cylinders were prepared for in vitro wire myography. Contraction to methacholine was measured in the presence or absence of organ bath quercetin and/or Nω-nitro-L-arginine methyl ester (L-NAME). Relaxation responses were evoked in preconstricted tissues using electrical field stimulation (EFS). Lung tumor necrosis factor-alpha (TNF-α) and interleukin-1β (IL-1β) levels were measured by enzyme-linked immunosorbent assay (ELISA). A P < 0.05 was considered statistically significant. Contractile responses of tracheal smooth muscle (TSM) of hyperoxic animals were significantly increased compared with AA animals (P < 0.001). Treatment with quercetin significantly reduced contraction in hyperoxic groups compared with hyperoxic control (P < 0.01), but did not have any effect in AA groups. In hyperoxic animals, relaxation of TSM was significantly reduced compared with AA animals (P < 0.001), while supplementation of quercetin restored the lost relaxation in hyperoxic groups. Incubation of preparations in L-NAME significantly reduced the quercetin effects on both contraction and relaxation (P < 0.01). Treatment of hyperoxic animals with quercetin significantly decreased the expression of TNF-α and IL-1β compared with hyperoxic controls (P < 0.001 and P < 0.01, respectively).The findings of this study demonstrate the protective effect of quercetin on airway hyperreactivity and suggest that quercetin might serve as a novel therapy to prevent and treat neonatal hyperoxia-induced airway hyperreactivity and inflammation.

Effect of arachidonic and docosahexaenoic acid supplementation on respiratory outcomes and neonatal morbidities in preterm infants

BACKGROUND & AIMS

Studies have suggested that supplementation with docosahexaenoic acid (DHA) to preterm infants might be associated with an increased risk of bronchopulmonary dysplasia (BPD). Our aim was to investigate the effect of enteral supplementation with arachidonic acid (ARA) and DHA on short-term respiratory outcomes and neonatal morbidities in very preterm infants.

METHODS

This is a secondary analysis of data from the ImNuT (Immature, Nutrition Therapy) study, a randomized double blind clinical trial. Infants with gestational age less than 29 weeks were randomized to receive a daily enteral supplement with ARA 100 mg/kg and DHA 50 mg/kg (intervention) or medium chain triglycerides (MCT) oil (control), from second day of life to 36 weeks postmenstrual age. Study outcomes included duration of respiratory support, incidence of BPD and other major morbidities associated with preterm birth.

RESULTS

120 infants with mean (SD) gestational age 26.4 (1.7) weeks were randomized and allocated to either the intervention or control group. Supplementation with ARA and DHA led to a significant reduction in number of days with respiratory support (mean (95% CI) 63.4 (56.6-71.3) vs 80.6 (72.4-88.8); p = 0.03) and a lower oxygen demand (FiO₂) (mean (95% CI) 0.26 (0.25-0.28) vs 0.29 (0.27-0.30); p = 0.03) compared to control treatment. There were no clinically important differences in incidence of BPD and other major morbidities between the treatment groups.

CONCLUSIONS

Supplementation with ARA and DHA to preterm infants was safe and might have a beneficial effect on respiratory outcomes.

CLINICAL TRIAL REGISTRATION

The trial has been registered in www.

CLINICALTRIALS

gov, ID: NCT03555019.

Perinatal Inflammatory Biomarkers and Respiratory Disease in Preterm Infants

OBJECTIVE

To measure plasma levels of vascular endothelial growth factor (VEGF) and several cytokines (Interleukin [IL]-6 IL-8, IL-10) during the first week of life to examine the relationship between protein expression and likelihood of developing respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD).

STUDY DESIGN

Levels of IL-6, IL-8, IL-10, and VEGF were measured from plasma obtained from preterm patients during the first week of life. Newborns were recruited from a single center between April 2009 and April 2019. Criteria for the study included being inborn, birth weight of less than 1500 grams, and a gestational age of less than 32 weeks at birth.

RESULTS

The development of RDS in preterm newborns was associated with lower levels of VEGF during the first week of life. Higher plasma levels of IL-6 and IL-8 plasma were associated with an increased likelihood and increased severity of BPD at 36 weeks postmenstrual age. In contrast, plasma levels of VEGF, IL-6, IL-8, and IL-10 obtained during the first week of life were not associated with respiratory symptoms and acute care use in young children with BPD in the outpatient setting.

CONCLUSIONS

During the first week of life, lower plasma levels of VEGF was associated with the diagnosis of RDS in preterm infants. Preterm infants with higher levels of IL-6 and IL-8 during the first week of life were also more likely to be diagnosed with BPD. These biomarkers may help to predict respiratory morbidities in preterm newborns during their initial hospitalization.

Effect of washed versus unwashed red blood cells on transfusion-related immune responses in preterm newborns

Objectives

Transfusion with washed packed red blood cells (PRBCs) may be associated with reduced transfusion‐related pro‐inflammatory cytokine production. This may be because of alterations in recipient immune responses.

Methods

This randomised trial evaluated the effect of transfusion with washed compared with unwashed PRBCs on pro‐inflammatory cytokines and endothelial activation in 154 preterm newborns born before 29 weeks’ gestation. Changes in plasma cytokines and measures of endothelial activation in recipient blood were analysed after each of the first three transfusions.

Results

By the third transfusion, infants receiving unwashed blood had an increase in IL‐17A (P = 0.04) and TNF (P = 0.007), whereas infants receiving washed blood had reductions in IL‐17A (P = 0.013), TNF (P = 0.048), IL‐6 (P = 0.001), IL‐8 (P = 0.037), IL‐12 (P = 0.001) and IFN‐γ (P = 0.001). The magnitude of the post‐transfusion increase in cytokines did not change between the first and third transfusions in the unwashed group but decreased in the washed group for IL‐12 (P = 0.001), IL‐17A (P = 0.01) and TNF (P = 0.03), with the difference between the groups reaching significance by the third transfusion (P < 0.001 for each cytokine).

Conclusion

The pro‐inflammatory immune response to transfusion in preterm infants can be modified when PRBCs are washed prior to transfusion. Further studies are required to determine whether the use of washed PRBCs for neonatal transfusion translates into reduced morbidity and mortality.

Management Practices During Perinatal Respiratory Transition of Very Premature Infants

The present review considers some controversial management practices during extremely premature perinatal transition. We focus on perinatal prevention and treatment of respiratory distress syndrome (RDS) in immature infants. New concerns regarding antenatal corticosteroid management have been raised. Many fetuses are only exposed to potential adverse effects of the drug. Hence, the formulation and the dosage may need to be modified. Another challenge is to increase the fraction of the high-risk fetuses that benefit from the drug and to minimize the harmful effects of the drug. On the other hand, boosting anti-inflammatory and anti-microbial properties of surfactant requires further attention. Techniques of prophylactic surfactant administration to extremely immature infants at birth may be further refined. Also, new findings suggest that prophylactic treatment of patent ductus arteriosus (PDA) of a high-risk population rather than later selective closure of PDA may be preferred. The TREOCAPA trial (Prophylactic treatment of the ductus arteriosus in preterm infants by acetaminophen) evaluates, whether early intravenous paracetamol decreases the serious cardiorespiratory consequences following extremely premature birth. Lastly, is inhaled nitric oxide (iNO) used in excess? According to current evidence, iNO treatment of uncomplicated RDS is not indicated. Considerably less than 10% of all very premature infants are affected by early persistence of pulmonary hypertension (PPHN). According to observational studies, effective ventilation combined with early iNO treatment are effective in management of this previously fatal disease. PPHN is associated with prolonged rupture of fetal membranes and birth asphyxia. The lipopolysaccharide (LPS)-induced immunotolerance and hypoxia-reperfusion-induced oxidant stress may inactivate NO-synthetases in pulmonary arterioles and terminal airways. Prospective trials on iNO in the management of PPHN are indicated. Other pulmonary vasodilators may be considered as comparison drugs or adjunctive drugs. The multidisciplinary challenge is to understand the regulation of pregnancy duration and the factors participating the onset of extremely premature preterm deliveries and respiratory adaptation. Basic research aims to identify deficiencies in maternal and fetal tissues that predispose to very preterm births and deteriorate the respiratory adaptation of immature infants. Better understanding on causes and prevention of extremely preterm births would eventually provide effective antenatal and neonatal management practices required for the intact survival.

The Relationship Between Cord Blood Cytokine Levels and Perinatal Characteristics and Bronchopulmonary Dysplasia: A Case-Control Study

OBJECTIVE

To establish the association between serial levels of inflammatory cytokines in cord blood and perinatal characteristics and bronchopulmonary dysplasia (BPD) in preterm infants.

METHODS

147 premature infants with gestational age ≤32 weeks who were born and hospitalized in the First Affiliated Hospital of Zhengzhou University between July 2019 and August 2021 were enrolled in this retrospective case-control study. Multiple microsphere flow immunofluorescence was used to detect seven cytokines in cord blood collected within 24 h of birth. Demographics, delivery characteristics, maternal factors, neonatal characteristics, and clinical outcomes were collected for the two groups. An unconditional logistic regression model was used in this study to assess the clinical variables.

RESULTS

IL-6 cord blood levels at birth were significantly higher in the BPD group than in the non-BPD group, but the odds ratio (OR) was very small (OR = 1). No differences in other cytokine concentrations were observed between the two groups. Multivariable logistic regression analysis demonstrated that increased maternal white blood cell (WBC) count on admission and lower birth weight increased the risk of BPD progression.

CONCLUSIONS

Increased IL-6 cord blood levels at birth in preterm infants may have trivial significance for predicting BPD. Furthermore, higher maternal WBC count on admission and lower birth weight increased the risk of BPD.

Impact of Co-Existing Placental Pathologies in Pregnancies Complicated by Placental Abruption and Acute Neonatal Outcomes

Placental abruption (PA) is a concern for maternal and neonatal morbidity. Adverse neonatal outcomes in the setting of PA include higher risk of prematurity. Placental pathologies include maternal vascular malperfusion (MVM), fetal vascular malperfusion (FVM), acute chorioamnionitis, and villitis of unknown etiology (VUE). We aimed to investigate how placental pathology contributes to acute neonatal outcome in PA. A retrospective cohort study of all placentas with PA were identified. Exposures were MVM, FVM, acute chorioamnionitis and VUE. The primary outcome was NICU admission and the secondary outcomes included adverse base deficit and Apgar scores, need for resuscitation, and small-for-gestational age. A total of 287 placentas were identified. There were 160 (59.9%) of placentas with PA alone vs 107 (40.1%) with PA and additional placental pathologies. Odds of NICU admission were more than two times higher in pregnancies with placental pathologies (OR = 2.37, 95% CI 1.28-4.52). These estimates were in large part mediated by prematurity and birthweight, indirect effect acting through prematurity was OR 1.79 (95% CI 1.12-2.75) and through birthweight OR 2.12 (95% CI 1.40-3.18). Odds of Apgar score ≤ 5 was more than four times higher among pregnancies with placental pathologies (OR = 4.56, 95% CI 1.28-21.26). Coexisting placental pathology may impact Apgar scores in pregnancies complicated by PA. This knowledge could be used by neonatal teams to mobilize resources in anticipation of the need for neonatal resuscitation.

Inflammatory biomarkers in very preterm infants during early intravenous paracetamol administration

BACKGROUND

Paracetamol promotes early closure of patent ductus arteriosus (PDA), and it may affect inflammation after preterm birth.

OBJECTIVE

The aim of this study was to evaluate the association between paracetamol treatment and serum inflammatory biomarkers in very preterm infants with respiratory distress.

STUDY DESIGN

The infants were randomly assigned to intravenous paracetamol or placebo during the first 4 days of life, and others received a lower dose of paracetamol unblinded. Serum samples were used for the analysis of 10 cytokines, C-reactive protein (CRP) and malondialdehyde (MDA). The impact of paracetamol on the biomarkers was evaluated, based on the levels during the early (<60 h) and the later (60-120 h) postnatal age.

RESULTS

Altogether, 296 serum samples from 31 paracetamol and 25 placebo group infants were analysed. Paracetamol had no effect on cytokine levels during the first 60 h when most induced PDA contractions took place. Later paracetamol treatment was associated with lower serum levels of several cytokines, including interleukin (IL-) 10, interferon gamma-induced protein (IP-) 10, and monocyte chemoattractant protein-1. CRP levels were lower in the paracetamol group during the early treatment. Amongst the infants who had severe morbidities, MDA was higher (p = .045), regardless of paracetamol treatment.

CONCLUSION

No significant differences in the cytokine levels were evident between the treatment and placebo groups. However, during early treatment, CRP levels were lower in the paracetamol group. To clarify whether this was due to a decrease in cardiopulmonary distress, or a distinct anti-inflammatory effect, requires further studies.

Perinatal inflammation relates to early respiratory morbidity and lung function at 12 years of age in children born very preterm

AIM

Very preterm birth may be associated with lung function impairment later in life. It is not known if this is caused by prematurity per se or by associated perinatal events, such as maternal-foetal inflammation and severity of early neonatal lung disease. We assessed these factors in a prospective cohort of very preterm infants followed from birth to middle school age.

METHODS

In 71 infants with a gestational age of median 27.4 (range 23.9-31.7) weeks, pro-inflammatory and modulatory cytokines were measured in umbilical cord blood and in arterial blood sampled at 6, 24 and 72 h after birth, and cumulated cytokine concentrations were calculated as area under the curve (AUC). At median 12.6 (range 12.3-13.5) years of age, pulmonary function testing was done in 53 children.

RESULTS

There was a positive correlation between days on mechanical ventilation and AUC for IL-6 (p = 0.001), IL-8 (p = 0.015) and IL-10 (p = 0.006). Infants with bronchopulmonary dysplasia (BPD; n = 32) had higher AUC for the cytokines IL-6, IL-8 and IL-10 than those without BPD (all p < 0.01). Higher levels of AUC for IL-6 at birth correlated with lower forced expiratory volume in 1 s (p = 0.030) and lower mean expiratory flow rate between 25 and 75% of forced vital capacity (p = 0.034).

CONCLUSION

Perinatal inflammation, assessed by circulating cytokines in the first three days of life, was associated with BPD and with airway obstruction at 12 years of age.

Salivary cytokine - A non-invasive predictor for bronchopulmonary dysplasia in premature neonates

BACKGROUND

To find a less invasive method of cytokine detection for premature neonates, we conducted this cohort study to investigate the salivary cytokines and to analyze their correlations with bronchopulmonary dysplasia (BPD).

METHODS

Premature neonates younger than 34 weeks of gestational age without maternal or neonatal infection were recruited. Salivary samples were collected on their first (D1) and seventh (D7) days of life. The cytokine levels were detected by MILLPLEX® MAP Human multiplex assay. One-way analysis of variance, the Kruskal-Wallis test, Pearson's chi-square test, and logistic regression were used to analyze the data.

RESULTS

Totally 125 neonates were enrolled and separated into four groups: control, mild, moderate, and severe BPD group. The salivary levels of D1 interleukin (IL)-6, IL-8, IL-10, IL-17, interferon (IFN)-γ, and D7 IL-6 (p = 0.001, 0.001, 0.000, 0.043, 0.037 and 0.001, respectively) were significantly higher in the BPD groups than in the control group. After adjusting for the gestational age, acid-base equivalent, and absolute neutrophil count, comparing to the control group, the levels of D7 IL-17 became significantly lower in all three BPD groups (p = 0.032, 0.030, and 0.030, respectively) and that of D7 IFN-α2 became significantly lower in the severe BPD group (p = 0.037).

CONCLUSION

Early-life salivary cytokine levels were correlated with the development of BPD in premature neonates. This study provides a novel method to predict BPD early and non-invasively.

Effects of nutrition therapy on growth, inflammation and metabolism in immature infants: a study protocol of a double-blind randomized controlled trial (ImNuT)

Background

Current nutritional management of infants born very preterm results in significant deficiency of the essential fatty acids (FAs) arachidonic acid (ARA) and docosahexaenoic acid (DHA). The impact of this deficit on brain maturation and inflammation mediated neonatal morbidities are unknown. The aim of this study is to determine whether early supply of ARA and DHA improves brain maturation and neonatal outcomes in infants born before 29 weeks of gestation.

Methods

Infants born at Oslo University Hospital are eligible to participate in this double-blind randomized controlled trial. Study participants are randomized to receive an enteral FA supplement of either 0.4 ml/kg MCT-oil™ (medium chain triglycerides) or 0.4 ml/kg Formulaid™ (100 mg/kg of ARA and 50 mg/kg of DHA). The FA supplement is given from the second day of life to 36 weeks’ postmenstrual age (PMA). The primary outcome is brain maturation assessed by Magnetic Resonance Imaging (MRI) at term equivalent age. Secondary outcomes include quality of growth, incidence of neonatal morbidities, cardiovascular health and neuro-development. Target sample size is 120 infants (60 per group), this will provide 80% power to detect a 0.04 difference in mean diffusivity (MD, mm²/sec) in major white matter tracts on MRI.

Discussion

Supplementation of ARA and DHA has the potential to improve brain maturation and reduce inflammation related diseases. This study is expected to provide valuable information for future nutritional guidelines for preterm infants.

Trial registration

Clinicaltrials.gov ID: NCT03555019. Registered 4 October 2018- Retrospectively registered.

Effect of Maternal Docosahexaenoic Acid Supplementation on Bronchopulmonary Dysplasia-Free Survival in Breastfed Preterm Infants: A Randomized Clinical Trial

IMPORTANCE

Maternal docosahexaenoic acid (DHA) supplementation may prevent bronchopulmonary dysplasia, but evidence remains inconclusive.

OBJECTIVE

To determine whether maternal DHA supplementation during the neonatal period improves bronchopulmonary dysplasia-free survival in breastfed infants born before 29 weeks of gestation.

DESIGN, SETTING, AND PARTICIPANTS

Superiority, placebo-controlled randomized clinical trial at 16 Canadian neonatal intensive care units (June 2015-April 2018 with last infant follow-up in July 2018). Lactating women who delivered before 29 weeks of gestation were enrolled within 72 hours of delivery. The trial intended to enroll 800 mothers, but was stopped earlier.

INTERVENTIONS

There were 232 mothers (273 infants) assigned to oral capsules providing 1.2 g/d of DHA from randomization to 36 weeks' postmenstrual age and 229 mothers (255 infants) assigned to placebo capsules.

MAIN OUTCOMES AND MEASURES

The primary outcome was bronchopulmonary dysplasia-free survival in infants at 36 weeks' postmenstrual age. There were 22 secondary outcomes, including mortality and bronchopulmonary dysplasia.

RESULTS

Enrollment was stopped early due to concern for harm based on interim data from this trial and from another trial that was published during the course of this study. Among 461 mothers and their 528 infants (mean gestational age, 26.6 weeks [SD, 1.6 weeks]; 253 [47.9%] females), 375 mothers (81.3%) and 523 infants (99.1%) completed the trial. Overall, 147 of 268 infants (54.9%) in the DHA group vs 157 of 255 infants (61.6%) in the placebo group survived without bronchopulmonary dysplasia (absolute difference, -5.0% [95% CI, -11.6% to 2.6%]; relative risk, 0.91 [95% CI, 0.80 to 1.04], P = .18). Mortality occurred in 6.0% of infants in the DHA group vs 10.2% of infants in the placebo group (absolute difference, -3.9% [95% CI, -6.8% to 1.4%]; relative risk, 0.61 [95% CI, 0.33 to 1.13], P = .12). Bronchopulmonary dysplasia occurred in 41.7% of surviving infants in the DHA group vs 31.4% in the placebo group (absolute difference, 11.5% [95% CI, 2.3% to 23.2%]; relative risk, 1.36 [95% CI, 1.07 to 1.73], P = .01). Of 22 prespecified secondary outcomes, 19 were not significantly different.

CONCLUSIONS AND RELEVANCE

Among breastfed preterm infants born before 29 weeks of gestation, maternal docosahexaenoic acid supplementation during the neonatal period did not significantly improve bronchopulmonary dysplasia-free survival at 36 weeks' postmenstrual age compared with placebo. Study interpretation is limited by early trial termination.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02371460.

Analysis of interleukins 6, 8, 10 and 17 in the lungs of premature neonates with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is an abnormality that occurs in premature neonate lung development. The pathophysiology is uncertain, but the inflammatory response to lung injury may be the responsible pathway. The objective of this study is to evaluate the role of interleukins 6, 8, 10, and 17 through the anatomopathological and immunohistochemical study of the lungs of premature neonates with BPD. Thirty-two cases of neonatal autopsies from the Pathology Department of the Clinics Hospital of the Universidade Federal do Paraná, who presented between 1991 and 2005 were selected. The sample included neonates less than 34 weeks of gestational age who underwent oxygen therapy and had pulmonary formalin-fixed paraffin-embedded (FFPE) samples. Pulmonary specimens were later classified into three groups according to histopathological and morphometric changes (classic BPD, new BPD, and without BPD) and subjected to immunohistochemical analysis. The antibodies selected for the study were anti-IL-6, anti-IL-8, anti-IL-10, and anti-IL-17A monoclonal antibodies. IL-6, IL-8, and IL-10 showed no significant differences in tissue expression among the groups. IL-17A had higher tissue immunoreactivity in the group without BPD compared with the classic BPD group (1686 vs. 866 μm², p = 0.029). This study showed that the involvement of interleukins 6, 8, and 10 might not be significantly different between the two types of BPD. We speculated that IL-17A could be a protective factor in this disease.

IL-1β dysregulates cGMP signaling in the newborn lung

Cyclic guanosine monophosphate (cGMP) signaling is an important regulator of newborn lung function and development. Although cGMP signaling is decreased in many models of newborn lung injury, the mechanisms are poorly understood. We determined how IL-1β regulates the expression of the α1-subunit of soluble guanylate cyclase (sGCα1), a prime effector of pulmonary cGMP signaling. Physiologic levels of IL-1β were discovered to rapidly decrease sGCα1 mRNA expression in a human fetal lung fibroblast cell line (IMR-90 cells) and protein levels in primary mouse pup lung fibroblasts. This sGCα1 expression inhibition appeared to be at a transcriptional level; IL-1β treatment did not alter sGCα1 mRNA stability although it reduced sGCα1 promoter activity. TGFβ-activated kinase 1 (TAK1) was determined to be required for IL-1β's regulation of sGCα1 expression; TAK1 knockdown protected sGCα1 mRNA expression in IL-1β-treated IMR-90 cells. Moreover, heterologously expressed TAK1 was sufficient to decrease sGCα1 mRNA levels in those cells. Nuclear factor-kappaB (NF-κB) signaling played a critical role in the IL-1β-TAK1-sGCα1 regulatory pathway; chromatin immunoprecipitation studies demonstrated enhanced activated NF-kB subunit (RelA) binding to the sGCα1 promoter after IL-1β treatment unless were treated with an IκB kinase2 inhibitor. Also, this NF-kB signaling inhibition protected sGCα1 expression in IL-1β-treated fibroblasts. Lastly, using transgenic mice in which active IL-1β was conditionally expressed in lung epithelial cells, we established that IL-1β expression is sufficient to stimulate TAK1 and decrease sGCα1 protein expression in the newborn lung. Together these results detail the role and mechanisms by which IL-1β inhibits cGMP signaling in the newborn lung.

Immune and Inflammatory Proteins in Cord Blood as Predictive Biomarkers of Retinopathy of Prematurity in Preterm Infants

Purpose

To determine whether elevated levels of immune/inflammatory proteins in cord blood, alone or in combination with conventional clinical parameters, can predict the occurrence and progression of retinopathy of prematurity (ROP) in preterm infants.

Methods

This was a retrospective cohort study of 110 premature singleton infants who were born at ≤32.0 weeks. Cord plasma at birth was assayed for interleukin-6, C3a, C5a, matrix metalloproteinase-2 (MMP-2), MMP-9, tissue inhibitor of metalloproteinase-1, macrophage colony-stimulating factor, endostatin, a proliferation-inducing ligand, insulin-like growth factor-binding protein-1 (IGFBP-1), IGFBP-2, and calcium-binding protein A8/A9 complex levels. The primary outcome measures were the occurrence of any stage ROP, severe ROP (>stage 3), and vision-threatening type 1 ROP requiring laser treatment.

Results

ROP was diagnosed in 30 of 110 infants (27.3%), including 14 (12.7%) with severe ROP. Laser treatment was performed on 7 infants (6.4%). Multiple logistic regression analyses indicated that elevated levels of cord plasma IL-6 were significantly associated with severe ROP, whereas elevated levels of cord plasma C5a were significantly associated with ROP laser treatments. However, none of the proteins measured in the cord plasma were associated with ROP occurrence. Using a stepwise regression procedure, we developed a combined prediction model, which included high cord plasma IL-6 levels and low birth weight for severe ROP (area under the curve [AUC], 0.840), and high cord plasma C5a levels and low birth weight for laser treatment (AUC, 0.884).

Conclusions

Elevated levels of cord plasma IL-6 and C5a could be used as independent markers to predict severe ROP and laser treatment, respectively, with combined models predicting ROP progression with good accuracy.

Use of Azithromycin for the Prevention of Lung Injury in Mechanically Ventilated Preterm Neonates: A Randomized Controlled Trial

INTRODUCTION

Macrolides have anti-inflammatory and immunomodulatory properties that give this class of antibiotics a role that differs from its classical use as an antibiotic, which opens new therapeutic possibilities.

OBJECTIVE

The aim of this study was to evaluate the anti-inflammatory effect of azithromycin in preventing mechanical ventilation (MV)-induced lung injury in very-low-birth-weight preterm neonates.

METHODS

This is a randomized, double-blind, placebo-controlled trial of preterm neonates who received invasive MV within 72 h of birth. Patients were randomized to receive intravenous azithromycin (at a dose of 10/mg/kg/day for 5 days) or placebo (0.9% saline) within 12 h of the start of MV. Two blood samples were collected (before and after intervention) for measurement of interleukins (ILs) and PCR for Ureaplasma. Patients were followed up throughout the hospital stay for the outcomes of death and broncho-pulmonary dysplasia defined as need for oxygen for a period of ≥28 days of life (registered at ClinicalTrials.gov, No. NCT03485703).

RESULTS

Forty patients were analyzed in the azithromycin group and 40 in the placebo group. Five days after the last dose, serum IL-2 and IL-8 levels dropped significantly in the azithromycin group. There was a significant reduction in the incidence of death and O2 dependency at 28 days/death in azithromycin-treated patients regardless of the detection of Ureaplasma in blood.

CONCLUSIONS

Azithromycin has anti-inflammatory effects, with a decrease in cytokines after 5 days of use and a reduction in death and O2 dependency at 28 days/death in mechanically ventilated preterm neonates.

Association of Chorioamnionitis With Bronchopulmonary Dysplasia Among Preterm Infants: A Systematic Review, Meta-analysis, and Metaregression

IMPORTANCE

Bronchopulmonary dysplasia (BPD), a chronic lung disease of prematurity, remains one of the major and most common complications of very preterm birth. Insight into factors associated with the pathogenesis of BPD is key to improving its prevention and treatment.

OBJECTIVE

To perform a systematic review, meta-analysis, and metaregression of clinical studies exploring the association between chorioamnionitis (CA) and BPD in preterm infants.

DATA SOURCES

PubMed and Embase were searched without language restriction (last search, October 1, 2018). Key search terms included bronchopulmonary dysplasia, chorioamnionitis, and risk factors.

STUDY SELECTION

Included studies were peer-reviewed studies examining preterm (<37 weeks' gestation) or very low-birth-weight (<1500 g) infants and reporting primary data that could be used to measure the association between exposure to CA and the development of BPD.

DATA EXTRACTION AND SYNTHESIS

The Meta-analysis of Observational Studies in Epidemiology (MOOSE) guideline was followed. Data were independently extracted by 2 researchers. A random-effects model was used to calculate odds ratios (ORs) and 95% CIs. Heterogeneity in effect size across studies was studied using multivariate, random-effects metaregression analysis.

MAIN OUTCOMES AND MEASURES

The primary outcome was BPD, defined as supplemental oxygen requirement on postnatal day 28 (BPD28) or at the postmenstrual age of 36 weeks (BPD36). Covariates considered as potential confounders included differences between CA-exposed and CA-unexposed infants in gestational age, rates of respiratory distress syndrome (RDS), exposure to antenatal corticosteroids, and rates of early- and late-onset sepsis.

RESULTS

A total of 3170 potentially relevant studies were found, of which 158 met the inclusion criteria (244 096 preterm infants, 20 971 CA cases, and 24 335 BPD cases). Meta-analysis showed that CA exposure was significantly associated with BPD28 (65 studies; OR, 2.32; 95% CI, 1.88-2.86; P < .001; heterogeneity: I2 = 84%; P < .001) and BPD36 (108 studies; OR, 1.29; 95% CI, 1.17-1.42; P < .001; heterogeneity: I2 = 63%; P < .001). The association between CA and BPD remained significant for both clinical and histologic CA. In addition, significant differences were found between CA-exposed and CA-unexposed infants in gestational age, birth weight, odds of being small for gestational age, exposure to antenatal corticosteroids, and early- and late-onset sepsis. Chorioamnionitis was not significantly associated with RDS (48 studies; OR, 1.10; 95% CI, 0.92-1.34; P = .24; heterogeneity: I2 = 90%; P < .001), but multivariate metaregression analysis with backward elimination revealed that a model combining the difference in gestational age and the odds of RDS was associated with 64% of the variance in the association between CA and BPD36 across studies.

CONCLUSIONS AND RELEVANCE

The results of this study confirm that among preterm infants, exposure to CA is associated with a higher risk of developing BPD, but this association may be modulated by gestational age and risk of RDS.

Inflammation in the neonatal period and intrauterine growth restriction aggravate bronchopulmonary dysplasia

BACKGROUND

To investigate the hematological features of infants with bronchopulmonary dysplasia (BPD) and their relationships with clinical severity.

METHODS

This prospective observational study enrolled 73 BPD patients from a total of 331 infants with a birth weight of <1500 g from 2005 to 2013. The clinical severity of BPD was defined by the duration of oxygen supplementation and positive pressure ventilation (PPV) in line with the diagnostic criteria of BPD. The hematological status and cytokine levels were surveyed from blood samples at birth and at 2 and 4 weeks of life.

RESULTS

Thirty-four (46.6%) cases were classified as "moderate-to-severe" BPD. Small-for-gestational-age (SGA) was associated with the severity of BPD (OR: 5.05; 95% CI: 1.45 to 17.2). The CRP level at 2 weeks (partial regression coefficient [rc]: 21.8; 4.01 to 39.7) and the neutrophil count at 4 weeks (0.005; 0.001 to 0.007) were positively correlated with the oxygenation period. The PPV period was found to be correlated with the CRP level at 2 weeks (27.2; 14.9 to 39.5), and the neutrophil count (0.003; 0.001 to 0.004) at 4 weeks.

CONCLUSION

The aggravation of BPD was associated with both SGA at birth and inflammation during neonatal period.

Exploration of potential biochemical markers for persistence of patent ductus arteriosus in preterm infants at 22-27 weeks' gestation

BACKGROUND

Early identification of infants at risk for complications from patent ductus arteriosus (PDA) may improve treatment outcomes. The aim of this study was to identify biochemical markers associated with persistence of PDA, and with failure of pharmacological treatment for PDA, in extremely preterm infants.

METHODS

Infants born at 22-27 weeks' gestation were included in this prospective study. Blood samples were collected on the second day of life. Fourteen biochemical markers associated with factors that may affect PDA closure were analyzed and related to persistent PDA and to the response of pharmacological treatment with ibuprofen.

RESULTS

High levels of B-type natriuretic peptide, interleukin-6, -8, -10, and -12, growth differentiation factor 15 and monocyte chemotactic protein 1 were associated with persistent PDA, as were low levels of platelet-derived growth factor. High levels of erythropoietin were associated with both persistent PDA and failure to close PDA within 24 h of the last dose of ibuprofen.

CONCLUSIONS

High levels of inflammatory markers were associated with the persistence of PDA. High levels of erythropoietin were associated with both the persistence of PDA and failure to respond to pharmacological treatment.

Bedside Measurement of Volatile Organic Compounds in the Atmosphere of Neonatal Incubators Using Ion Mobility Spectrometry

Background: Early and non-invasive diagnosis of common diseases is of great importance in the care of preterm infants. We hypothesized that volatile organic compounds (VOC) can be successfully measured in the neonatal incubator atmosphere. Methods: This is a feasibility study to investigate whether the discrimination of occupied and unoccupied neonatal incubators is possible by bedside measurement of volatile organic compounds (VOCs) on the neonatal intensive care unit. VOC profiles were measured in the incubator air using ion mobility spectrometry coupled to multi-capillary columns (BreathDiscovery B&S Analytik GmbH, Dortmund, Germany). Results: Seventeen incubators occupied by preterm infants (50 measurements) and nine unoccupied neonatal incubators were sampled, using 37 room air measurements as controls. Three VOC signals that allow the discrimination between occupied and unoccupied incubators were identified. The best discrimination was reached by peak P20 exhibiting a sensitivity, specificity, positive predictive value and negative predictive value of 94.0, 88.9, 97.3, and 72.3%, respectively. Use of a decision tree improved these values to 100.0, 88.9, 98.0, and 100.0%, respectively. Discussion: A bedside method that allows the characterization of VOC profiles in the neonatal incubator atmosphere using ion mobility spectrometry was established. Occupied and unoccupied incubators could be discriminated by characterizing VOC profiles. This technique has the potential to yield results within minutes. Thus, future studies are recommended to test the hypothesis that VOCs within neonatal incubators are useful biomarkers for non-invasive diagnostics in preterm neonates.

Bronchopulmonary dysplasia: Pathogenesis and treatment

Bronchopulmonary dysplasia (BPD) is a form of chronic lung disease of infancy, which mostly affects premature infants with significant morbidity and mortality. Premature infants who require to be treated for conditions including respiratory distress syndrome have a higher risk of developing BPD. In spite of the improvement in clinical methods, the incidence of BPD has not reduced. In the present review, the pathogenesis of BPD is described along with the treatments available at present and the role of nursing in the management of BPD. Emerging preventive therapies for BPD are also discussed, including the use of recombinant human superoxide dismutase, which has been proven effective in reducing respiratory injury and its long-term effects.

Review shows that using surfactant a number of times or as a vehicle for budesonide may reduce the risk of bronchopulmonary dysplasia

AIM

Bronchopulmonary dysplasia (BPD) remains the most common respiratory morbidity in immature infants. This review describes the diagnosis of BPD has evolved and summarises the therapeutic approaches that have made it possible to limit the incidence of BPD.

METHOD

We reviewed the literature from the first definition of BPD by Northway in 1967 to the surfactant treatment policies that are currently in use, drawing on more than 50 papers up to 2017.

RESULTS

Our review showed that improvements in neonatal survival have been associated with an increased risk of severe BPD, significant levels of long-term morbidity and the increased use of healthcare resources. These issues have encouraged researchers to explore potential new treatments that limit the incidence of BPD. Repeated surfactant instillation and the use of surfactant as a vehicle for budesonide are promising strategies for alleviating the burden of chronic lung disease. Ongoing research on surfactant or stem cell therapy may further improve the respiratory prognosis for prematurely born children.

CONCLUSION

Considerable research has been carried out into the increase in BPD, which has resulted from improvements in neonatal survival. Key areas of research include repeated surfactant administration, using surfactant as a vehicle for budesonide and stem cell therapy.

Serum cytokine concentrations, chorioamnionitis and the onset of bronchopulmonary dysplasia in premature infants

OBJECTIVE

To investigate the relationships between serum cytokine concentrations and chorioamnionitis (CAM) and CAM-related bronchopulmonary dysplasia (BPD) in premature infants.

METHODS

Serum was collected at 0 and 7 days after birth from 36 premature infants born at <32 weeks of gestation. We examined the relationships between 30 cytokine concentrations and CAM, BPD, and other perinatal factors.

RESULTS

On day 0, GM-CSF, IL-15, IL-17, IL-2, IL-2R, VEGF, and MIG concentrations were significantly higher in the CAM group (n = 17) than in the non-CAM group (n = 19). These concentrations had decreased by day 7 and were similar in both groups. The IL-12p70 concentration on day 0 was significantly lower in the BPD group (n = 16) than in the non-BPD group (n = 15). BPD incidence was similar between the CAM and non-CAM groups.

CONCLUSIONS

These data support the hypothesis that intrauterine inflammation is not a primary risk factor for BPD. The immunological environment at birth or soon after, rather than intrauterine fetal inflammation (e.g., CAM), is a primary risk factor for BPD onset in preterm infants. Decreased inflammatory responses are particularly relevant, as indicated by the relationship between BPD and low serum IL-12p70 concentrations on day 0.

A Time-Based Analysis of Inflammation in Infants at Risk of Bronchopulmonary Dysplasia

OBJECTIVE

To precisely delineate the timing and contribution of inflammation to bronchopulmonary dysplasia (BPD) in preterm infants during the neonatal period.

STUDY DESIGN

Longitudinal study of blood inflammatory biomarkers (interleukin [IL]-6, IL-8, and granulocyte colony-stimulating factor) measured between birth and 42 days of age, at high temporal (daily) resolution, in infants born at or below 30 weeks of gestation. Cytokine predictors of BPD at 36 weeks postmenstrual age were adjusted for infant-specific and time-dependent factors, using hierarchical mixed effects regressions models.

RESULTS

A total of 1518 data points were obtained in 62 infants (mean gestational age of 27 weeks). Infants who developed BPD later on presented increased inflammation after birth compared with infants without BPD. Inflammation was sustained, with gradual attenuation over 2 weeks (IL-8: OR: 6.5 [95% CI: 1.8-24]; granulocyte colony-stimulating factor: 3.3 [1.5-7.6]) and was higher in boys and in infants of lower birth weight. This inflammation preceded the clinical increased requirement in supplemental oxygen characteristic of BPD, and preceded the peak occurrence of neonatal sepsis or necrotizing enterocolitis.

CONCLUSIONS

Systemic inflammation occurs early in the neonatal period and precedes clinical symptoms in infants with BPD. These data provide a discrete vulnerability window period, supporting a role for targeted intensive care interventions during the early phase of BPD.

IL-17 in neonatal health and disease

Over the last few years, scientific interest in the cytokine IL-17A has intensified as its role in human health and disease has been elucidated. Discovered almost a quarter century ago, IL-17A is known to have poor biologic activity when acting alone, but attains robust actions when working synergistically with potent mediators of proinflammatory immune responses, such as IL-6 and IL-8. IL-17A is produced by specialized innate immune cells that protect host barriers from the outside world. Like sentries, these innate immune cells can "sound the alarm" through increased production of IL-17A, causing activation and recruitment of primed neutrophils and monocytes when pathogens escape initial host defenses. In this way, IL-17A promulgates mechanisms responsible for pathogen death and clearance. However, when IL-17A pathways are triggered during fetal development, due to chorioamnionitis or in utero inflammatory conditions, IL-17A can instigate and/or exacerbate fetal inflammatory responses that increase neonatal morbidities and mortality associated with common neonatal conditions such as sepsis, bronchopulmonary dysplasia (BPD), patent ductus arteriosus (PDA), and necrotizing enterocolitis (NEC). This review details the ontogeny of IL-17A in the fetus and newborn, discusses how derangements in its production can lead to pathology, and describes known and evolving therapies that may attenuate IL-17A-mediated human conditions.

IKKβ Activation in the Fetal Lung Mesenchyme Alters Lung Vascular Development but Not Airway Morphogenesis

In the immature lung, inflammation and injury disrupt the epithelial-mesenchymal interactions required for normal development. Innate immune signaling and NF-κB activation disrupt the normal expression of multiple mesenchymal genes that play a key role in airway branching and alveolar formation. To test the role of the NF-κB pathway specifically in lung mesenchyme, we utilized the mesenchymal Twist2-Cre to drive expression of a constitutively active inhibitor of NF-κB kinase subunit β (IKKβca) mutant in developing mice. Embryonic Twist2-IKKβca mice were generated in expected numbers and appeared grossly normal. Airway branching also appeared normal in Twist2-IKKβca embryos, with airway morphometry, elastin staining, and saccular branching similar to those in control littermates. While Twist2-IKKβca lungs did not contain increased levels of Il1b, we did measure an increased expression of the chemokine-encoding gene Ccl2. Twist2-IKKβca lungs had increased staining for the vascular marker platelet endothelial cell adhesion molecule 1. In addition, type I alveolar epithelial differentiation appeared to be diminished in Twist2-IKKβca lungs. The normal airway branching and lack of Il1b expression may have been due to the inability of the Twist2-IKKβca transgene to induce inflammasome activity. While Twist2-IKKβca lungs had an increased number of macrophages, inflammasome expression remained restricted to macrophages without evidence of spontaneous inflammasome activity. These results emphasize the importance of cellular niche in considering how inflammatory signaling influences fetal lung development.

Histologic Chorioamnionitis and Bronchopulmonary Dysplasia in Preterm Infants: The Epidemiologic Study on Low Gestational Ages 2 Cohort

OBJECTIVE

To investigate the association between histologic chorioamnionitis (HCA) and bronchopulmonary dysplasia (BPD) in very preterm infants, both in a general population and for those born after spontaneous preterm labor and after preterm premature rupture of membranes (pPROM).

STUDY DESIGN

This study included 2513 live born singletons delivered at 24-31 weeks of gestation from a national prospective population-based cohort of preterm births; 1731 placenta reports were available. HCA was defined as neutrophil infiltrates in the amnion, chorion of the membranes, or chorionic plate, associated or not with funisitis. The main outcome measure was moderate or severe BPD. Analyses involved logistic regressions and multiple imputation for missing data.

RESULTS

The incidence of HCA was 28.4% overall: 38% in cases of preterm labor, 64% in cases of pPROM, and less than 5% in cases of vascular disorders. Overall, the risk of BPD after adjustment for gestational age, sex, and antenatal steroids was reduced for infants with HCA (HCA alone: aOR 0.6 [95% CI 0.4-0.9]; associated with funisitis: aOR 0.5 [95% CI 0.3-0.8]). This finding was explained by the high rate of BPD and low rate of chorioamnionitis among children with fetal growth restriction. HCA was not associated with BPD in the preterm labor (13.4% vs 8.5%; aOR 0.9; 95% CI 0.5-1.8) or in the pPROM group (12.9% vs 12.1%; aOR 0.6; 95% CI 0.3-1.3).

CONCLUSION

In homogeneous groups of infants born after preterm labor or pPROM, HCA is not associated with BPD.

Correlates of Elevated Interleukin-6 and 8-Hydroxy-2'-Deoxyguanosine Levels in Tracheal Aspirates from Very Low Birth Weight Infants Who Develop Bronchopulmonary Dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) remains the most common complication of very low birth weight (VLBW) preterm infants, and inflammatory regulation plays a role in the development of the BPD. Interleukin-6 (IL-6) has an important role in airway inflammation and therefore can be used as a marker of airway injury. The study aimed to compare the changes between IL-6 and oxidative stress marker with 8-hydroxy-2'-deoxyguanosine (8-OHdG) from serum and tracheal aspiration (TA) in VLBW preterm infants following development of BPD.

METHODS

This birth cohort study enrolled 80 VLBW preterm infants, including 26 who developed BPD. All infants completed the study and survived at 36 weeks postmenstrual age. IL-6 and 8-OHdG concentrations from serum and TA on Day 1 and Day 28 after birth were measured using immunoassay.

RESULTS

IL-6 and 8-OHdG in serum and TA were higher in the BPD group than in the non-BPD group on the 1^st day after birth (p < 0.05). The IL-6 and 8-OHdG levels in TA fluid were persistently increased on the 28^th day of life in the BPD group (p < 0.05). The TA IL-6 was positively correlated with 8-OHdG levels on the 1^st day (r = 0.64, p < 0.05) and 28^th day of life (r = 0.76, p < 0.05). Based on receiver operating characteristic curves as a predictor of BPD development, TA IL-6 (cutoff, 456.8 pg/mg) had 81.5% sensitivity and 77.8% specificity, whereas TA 8-OHdG (cutoff, 4.4 ng/mg) had a sensitivity of 81.5% and a specificity of 64.4%.

CONCLUSION

Persistent inflammation with oxidative DNA damage in the respiratory tract may be a crucial mechanism in BPD.

Fetal inflammation associated with minimal acute morbidity in moderate/late preterm infants

OBJECTIVE

To determine whether exposure to acute chorioamnionitis and fetal inflammation caused short-term adverse outcomes.

DESIGN

This is a prospective observational study: subjects were mothers delivering at 32-36 weeks gestation and their preterm infants at a large urban tertiary level III perinatal unit (N=477 infants). Placentae and fetal membranes were scored for acute histological chorioamnionitis based on the Redline criteria. Fetal inflammation was characterised by histological diagnosis of funisitis (umbilical cord inflammation), increased cord blood cytokines measured by ELISA, and activation of the inflammatory cells infiltrating the placenta and fetal membranes measured by immunohistology. Maternal and infant data were collected.

RESULTS

Twenty-four per cent of 32-36-week infants were exposed to histological chorioamnionitis and 6.9% had funisitis. Immunostaining for leucocyte subsets showed selective infiltration of the placenta and fetal membranes with activated neutrophils and macrophages with chorioamnionitis. Interleukin (IL) 6, IL-8 and granulocyte colony-stimulating factor were selectively increased in the cord blood of preterm infants with funisitis. Compared with infants without chorioamnionitis, funisitis was associated with increased ventilation support during resuscitation (43.8% vs 15.4%) and more respiratory distress syndrome postnatally (27.3% vs 10.2%) in univariate analysis. However, these associations disappeared after adjusting for prematurity.

CONCLUSIONS

Despite fetal exposure to funisitis, increased cord blood cytokines and activated placental inflammatory cells, we could not demonstrate neonatal morbidity specifically attributable to fetal inflammation after adjusting for gestational age in moderate and late preterm infants.

Clinical chorioamnionitis at term V: umbilical cord plasma cytokine profile in the context of a systemic maternal inflammatory response

OBJECTIVE

Microbial invasion of the fetus due to intra-amniotic infection can lead to a systemic inflammatory response characterized by elevated concentrations of cytokines in the umbilical cord plasma/serum. Clinical chorioamnionitis represents the maternal syndrome often associated with intra-amniotic infection, although other causes of this syndrome have been recently described. The objective of this study was to characterize the umbilical cord plasma cytokine profile in neonates born to mothers with clinical chorioamnionitis at term, according to the presence or absence of bacteria and/or intra-amniotic inflammation.

MATERIALS AND METHODS

A cross-sectional study was conducted, including patients with clinical chorioamnionitis at term (n=38; cases) and those with spontaneous term labor without clinical chorioamnionitis (n=77; controls). Women with clinical chorioamnionitis were classified according to the results of amniotic fluid culture, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS) and amniotic fluid interleukin (IL)-6 concentration into three groups: 1) no intra-amniotic inflammation; 2) intra-amniotic inflammation without detectable microorganisms; or 3) microbial-associated intra-amniotic inflammation. A fetal inflammatory response syndrome (FIRS) was defined as an umbilical cord plasma IL-6 concentration >11 pg/mL. The umbilical cord plasma concentrations of 29 cytokines were determined with sensitive and specific V-PLEX immunoassays. Nonparametric statistical methods were used for analysis, adjusting for a false discovery rate of 5%.

RESULTS

1) Neonates born to mothers with clinical chorioamnionitis at term (considered in toto) had significantly higher median umbilical cord plasma concentrations of IL-6, IL-12p70, IL-16, IL-13, IL-4, IL-10 and IL-8, but significantly lower interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF)-α concentrations than neonates born to mothers with spontaneous term labor without clinical chorioamnionitis; 2) neonates born to mothers with clinical chorioamnionitis at term but without intra-amniotic inflammation had higher concentrations of IL-6, IL-12p70, IL-13, IL-4, IL-5, and IL-8, but lower IFN-γ, than neonates not exposed to clinical chorioamnionitis, suggesting that maternal fever in the absence of intra-amniotic inflammation leads to a change in the fetal cytokine network; 3) there were significant, positive correlations between maternal and umbilical cord plasma IL-6 and IL-8 concentrations (IL-6: Spearman correlation=0.53; P<0.001; IL-8: Spearman correlation=0.42; P<0.001), consistent with placental transfer of cytokines; 4) an elevated fetal plasma IL-6 (>11 pg/mL), the diagnostic criterion for FIRS, was present in 21% of cases (8/38), and all these neonates were born to mothers with proven intra-amniotic infection; and 5) FIRS was associated with a high concentration of umbilical cord plasma IL-8, IL-10 and monocyte chemoattractant protein (MCP)-1.

CONCLUSIONS

Neonates born to mothers with clinical chorioamnionitis at term had higher concentrations of umbilical cord plasma cytokines than those born to mothers without clinical chorioamnionitis. Even neonates exposed to clinical chorioamnionitis but not to intra-amniotic inflammation had elevated concentrations of multiple cytokines, suggesting that intrapartum fever alters the fetal immune response.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Systemic interleukin-2 administration improves lung function and modulates chorioamnionitis-induced pulmonary inflammation in the ovine fetus

Chorioamnionitis, an inflammatory reaction of the fetal membranes to microbes, is an important cause of preterm birth and associated with inflammation-driven lung injury. However, inflammation in utero overcomes immaturity of the premature lung by inducing surfactant lipids and lung gas volume. Previously, we found that lipopolysaccharide (LPS)-induced chorioamnionitis resulted in pulmonary inflammation with increased effector T cells and decreased regulatory T cell (Treg) numbers. Because Tregs are crucial for immune regulation, we assessed the effects of interleukin (IL)-2-driven selective Treg expansion on the fetal lung in an ovine chorioamnionitis model. Instrumented fetuses received systemic prophylactic IL-2 treatment [118 days gestational age (dGA)] with or without subsequent exposure to intra-amniotic LPS (122 dGA). Following delivery at 129 dGA (term 147 dGA), pulmonary and systemic inflammation, morphological changes, lung gas volume, and phospholipid concentration were assessed. IL-2 pretreatment increased the FoxP3(+)/CD3(+) ratio, which was associated with reduced CD3-positive cells in the fetal lungs of LPS-exposed animals. Prophylactic IL-2 treatment did not prevent pulmonary accumulation of myeloperoxidase- and PU.1-positive cells or elevation of bronchoalveolar lavage fluid IL-8 and systemic IL-6 concentrations in LPS-exposed animals. Unexpectedly, IL-2 treatment improved fetal lung function of control lambs as indicated by increased disaturated phospholipids and improved lung gas volume. In conclusion, systemic IL-2 treatment in utero preferentially expanded Tregs and improved lung gas volume and disaturated phospholipids. These beneficial effects on lung function were maintained despite the moderate immunomodulatory effects of prophylactic IL-2 in the course of chorioamnionitis.

Intrauterine endotoxin-induced impairs pulmonary vascular function and right ventricular performance in infant rats and improvement with early vitamin D therapy

High pulmonary vascular resistance (PVR), proximal pulmonary artery (PA) impedance, and right ventricular (RV) afterload due to remodeling contribute to the pathogenesis and severity of pulmonary hypertension (PH). Intra-amniotic exposure to endotoxin (ETX) causes sustained PH and high mortality in rat pups at birth, which are associated with impaired vascular growth and RV hypertrophy in survivors. Treatment of ETX-exposed pups with antenatal vitamin D (vit D) improves survival and lung growth, but the effects of ETX exposure on RV-PA coupling in the neonatal lung are unknown. We hypothesized that intrauterine ETX impairs RV-PA coupling through sustained abnormalities of PA stiffening and RV performance that are attenuated with vit D therapy. Fetal rats were exposed to intra-amniotic injections of ETX, ETX+vit D, or saline at 20 days gestation (term = 22 days). At postnatal day 14, pups had pressure-volume measurements of the RV and isolated proximal PA, respectively. Lung homogenates were assayed for extracellular matrix (ECM) composition by Western blot. We found that ETX lungs contain decreased α-elastin, lysyl oxidase, collagen I, and collagen III proteins (P < 0.05) compared control and ETX+vit D lungs. ETX-exposed animals have increased RV mechanical stroke work (P < 0.05 vs. control and ETX+vit D) and elastic potential energy (P < 0.05 vs. control and ETX+vit D). Mechanical stiffness and ECM remodeling are increased in the PA (P < 0.05 vs. control and ETX+vit D). We conclude that intrauterine exposure of fetal rats to ETX during late gestation causes persistent impairment of RV-PA coupling throughout infancy that can be prevented with early vit D treatment.

Gastric fluid cytokines are associated with chorioamnionitis and white blood cell counts in preterm infants

AIM

The aim of this study was to determine whether the concentration of cytokines in the gastric fluid at birth was associated with chorioamnionitis or funisitis and with the white blood cell counts of very premature newborns.

METHODS

We retrieved gastric fluid from 27 preterm infants with a gestational age of <29 weeks within 1 h of birth and used enzyme-linked immunosorbent assay to measure the concentrations of interleukin (IL)-1beta, epithelial cell-derived neutrophil-activating peptide (ENA)-78, IL-8 and growth-related oncogene (Gro)-alpha. The presence of histologic chorioamnionitis or funisitis in the placentas and the highest white blood cell count of the infants during the first week of life were compared to the cytokine concentrations.

RESULTS

Gastric fluid concentrations of IL-1beta, ENA-78, IL-8 and Gro-alpha were strongly associated with chorioamnionitis and funisitis. In addition, chorioamnionitis and funisitis and gastric aspirate cytokine levels were associated with the highest white blood cell counts of the infants during the first week of life.

CONCLUSION

This study suggests that levels of inflammatory cytokines in the gastric fluid of premature infants at birth can be used to assess the exposure of the infants to antenatal inflammation.

A study of genes encoding cytokines (IL6, IL10, TNF), cytokine receptors (IL6R, IL6ST), and glucocorticoid receptor (NR3C1) and susceptibility to bronchopulmonary dysplasia

Background

Bronchopulmonary dysplasia (BPD) is a common chronic lung disease associated with very preterm birth. The major risk factors include lung inflammation and lung immaturity. In addition, genetic factors play an important role in susceptibility to moderate-to-severe BPD. In this study, the aim was to investigate whether common polymorphisms of specific genes that are involved in inflammation or differentiation of the lung have influence on BPD susceptibility.

Methods

Genes encoding interleukin-6 (IL6) and its receptors (IL6R and IL6ST), IL-10 (IL10), tumor necrosis factor (TNF), and glucocorticoid receptor (NR3C1) were assessed for associations with moderate-to-severe BPD susceptibility. Five IL6, nine IL6R, four IL6ST, one IL10, two TNF, and 23 NR3C1 single nucleotide polymorphisms (SNPs) were analyzed in very preterm infants born in northern Finland (56 cases and 197 controls) and Canada (58 cases and 68 controls). IL-6, TNF and gp130 contents in umbilical cord blood, collected from very preterm infants, were studied for associations with the polymorphisms. Epistasis (i.e., interactions between SNPs in BPD susceptibility) was also examined. SNPs showing suggestive associations were analyzed in additional replication populations from Finland (39 cases and 188 controls) and Hungary (29 cases and 40 controls).

Results

None of the studied SNPs were associated with BPD nor were the IL6, TNF or IL6ST SNPs associated with cord blood IL-6, TNF and gp130, respectively. However, epistasis analysis suggested that SNPs in IL6ST and IL10 were associated interactively with risk of BPD in the northern Finnish population; however, this finding did not remain significant after correction for multiple testing and the finding was not replicated in the other populations.

Conclusions

We conclude that the analyzed SNPs within IL6, IL6R, IL6ST, IL10, TNF, and NR3C1 were not associated with BPD. Furthermore, there was no evidence that the studied SNPs directly contribute to the cord blood protein contents.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-014-0120-7) contains supplementary material, which is available to authorized users.

Detection of bloodstream infections and prediction of bronchopulmonary dysplasia in preterm neonates with an electronic nose

We show that smellprints of volatile organic components measured with an electronic nose (Cyranose 320; Smiths Detection Group Ltd, Watford, United Kingdom) differ between tracheal aspirates from preterm neonates with or without laboratory-confirmed bloodstream infections and with or without subsequent development of bronchopulmonary dysplasia. Tracheal aspirate smellprints could be useful noninvasive diagnostic markers for preterm neonates.

The evaluation of cord blood interleukin-1β levels in normal and caesarean deliveries

OBJECTIVE

The aim of this prospective study was to establish the cord blood interleukin 1β (IL-1β) levels and asphyxia enzymes in term newborns and their relationship between delivery modes. We investigated whether cord blood level of IL-1β could be used as a reliable marker for detecting hypoxic stress and to determine the optimal cut-off level for IL-1β.

METHODS

The study was designed prospectively. Cord blood samples were obtained at the time of delivery from 75 noninfected full-term neonates for the purpose of measuring cord blood levels of IL-1β. Women were classified into three groups according to the mode of delivery (20 vaginal delivery, 29 urgent caesarean section (with foetal distress) and 26 elective caesarean section). All cases were followed-up by hospitalization. Umbilical cord sampling was carried out for IL-1β, umbilical artery gas parameters and other asphyxia enzymes at the time of delivery. Cord blood IL-1β was measured by enzyme-linked immunosorbent assay. The perinatal outcomes of the cases were recorded after birth. Demographic characteristics, neonatal outcomes and laboratory findings were compared in all the three groups.

RESULTS

IL-1β levels showed statistically significant difference between groups (p < 0.01). The relationship was found between IL-1β cord blood levels and the mode of delivery. IL-1β levels of urgent caesarean section group were significantly higher than elective caesarean section and normal delivery group (p:0.001 and p:0.001, respectively). Normal delivery levels were significantly higher than the elective caesarean group (p:0.001).

CONCLUSION

Urgent section (foetal distress) and vaginal delivery (labour) were each associated with elevated IL-1β cord blood levels in noninfected full-term neonates, while only elective caesarean section was associated with decreased IL-1β levels. For the evaluation of newborns at high risk for perinatal hypoxic stress, cord blood IL-1β levels may lead the way. On the other hand, the mode of delivery may be associated with the effects on the immune system. Further investigations with larger patient groups are required to confirm our results.

Vitamin D treatment improves survival and infant lung structure after intra-amniotic endotoxin exposure in rats: potential role for the prevention of bronchopulmonary dysplasia

Vitamin D (vit D) has anti-inflammatory properties and modulates lung growth, but whether vit D can prevent lung injury after exposure to antenatal inflammation is unknown. We hypothesized that early and sustained vit D treatment could improve survival and preserve lung growth in an experimental model of bronchopulmonary dysplasia induced by antenatal exposure to endotoxin (ETX). Fetal rats (E20) were exposed to ETX (10 μg), ETX + Vit D (1 ng/ml), or saline (control) via intra-amniotic (IA) injections and delivered 2 days later. Newborn pups exposed to IA ETX received daily intraperitoneal injections of vit D (1 ng/g) or saline for 14 days. Vit D treatment improved oxygen saturations (78 vs. 87%; P < 0.001) and postnatal survival (84% vs. 57%; P < 0.001) after exposure to IA ETX compared with IA ETX alone. Postnatal vit D treatment improved alveolar and vascular growth at 14 days by 45% and 25%, respectively (P < 0.05). Vit D increased fetal sheep pulmonary artery endothelial cell (PAEC) growth and tube formation by 64% and 44%, respectively (P < 0.001), and prevented ETX-induced reductions of PAEC growth and tube formation. Vit D directly increased fetal alveolar type II cell (ATIIC) growth by 26% (P < 0.001) and enhanced ATIIC growth in the presence of ETX-induced growth suppression by 73% (P < 0.001). We conclude that antenatal vit D therapy improved oxygenation and survival in newborn rat pups and enhanced late lung structure after exposure to IA ETX in vivo, which may partly be due to direct effects on vascular and alveolar growth.

Biomarkers in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a complex disorder secondary to gene-environment interactions, and is the commonest chronic lung disease in infancy. There is no specific or effective treatment available to date for BPD. Since the aetiopathogenesis of BPD is multifactorial, involving diverse molecular signaling pathways, a variety of biomarkers detected in biological fluids have been proposed for early identification of infants predisposed to BPD. This review will be restricted to biomarker studies in human infants, conducted mostly in the last decade. The majority of the studies have been conducted using blood, urine or tracheal aspirate samples. Despite the multitude of biomarkers proposed, most studies have been conducted in small numbers of infants, with few being replicated by independent investigators. Confirmatory studies with adequate sample sizes and assessment of the role of putative biomarkers in the aetiology of BPD in developmentally appropriate animal models and human lungs with BPD will enhance the potential for therapeutic interventions. Genomic and proteomic approaches have the greatest potential to significantly advance the field of biomarkers in BPD.

Cytidine 5'-diphosphocholine ameliorates hyperoxic lung injury in a neonatal rat model

BACKGROUND

Bronchopulmonary dysplasia (BPD) is an important cause of morbidity. The aim of this study was to evaluate the preventive effect of cytidine 5'-diphosphocholine (CDP-choline) treatment on hyperoxic lung injury in a neonatal rat model.

METHODS

A total of 30 newborn pups were divided into control, hyperoxia, and hyperoxia + CDP-choline groups. After birth, pups in the control group were kept in room air and received saline injections, whereas those in hyperoxia and hyperoxia + CDP-choline groups were exposed to 95% O₂ and received daily injections of saline and CDP-choline throughout postnatal day 10, respectively. Histopathological scoring, radial alveolar count, lamellar body membrane protein expression, fibrosis, proinflammatory cytokine levels, lung tissue and bronchoalveolar lavage (BAL) fluid phospholipid content, and apoptosis were evaluated.

RESULTS

Hyperoxia-induced severe lung damage was reduced significantly by CDP-choline treatment. Radial alveolar count and lamellar body membrane protein expression were significantly recovered, and the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling-positive cells, active caspase-3 expression, and tissue proinflammatory cytokine levels were decreased by CDP-choline administration. Lung tissue and BAL phospholipid contents showed significant increases after CDP-choline administration.

CONCLUSION

These data show that CDP-choline ameliorates hyperoxic lung injury in a neonatal rat model. It may therefore be suggested that CDP-choline may be a novel therapeutic option for the prevention of BPD.

Soluble ST2 in the fetal inflammatory response syndrome: in vivo evidence of activation of the anti-inflammatory limb of the immune response

OBJECTIVE

Inflammation is a mechanism of host response to infection, which can be harmful when inappropriately modulated. Soluble ST2 (sST2) is a decoy receptor of interleukin (IL)-33, and this complex modulates the balance in the Th1/Th2 immune response. Moreover, sST2 inhibits the production of pro-inflammatory cytokines in cooperation with an anti-inflammatory cytokine, IL-10. The objectives of this study were to: (1) determine whether umbilical cord plasma sST2 concentration differs between preterm neonates with and without funisitis and between those with and without the fetal inflammatory response syndrome (FIRS); and (2) evaluate the relationship between sST2 and IL-10 among neonates with funisitis and/or FIRS.

METHODS

Umbilical cord plasma was collected from neonates delivered prematurely due to preterm labor or preterm prelabor rupture of membranes with (n = 36), and without funisitis (n = 30). FIRS (umbilical cord IL-6 concentration ≥ 17.5 pg/mL) was identified in 29 neonates. Plasma sST2 and IL-10 concentrations were determined by enzyme linked immune sorbent assay.

RESULTS

The median umbilical cord plasma sST2 concentration was 6.7-fold higher in neonates with FIRS than in those without FIRS (median 44.6 ng/mL, interquartile range (IQR) 13.8-80.3 ng/mL versus median 6.7 ng/mL, IQR 5.6-20.1 ng/mL; p < 0.0001). Similarly, the median umbilical cord plasma sST2 concentration was 2.7-fold higher in neonates with funisitis than in those without funisitis (median 19.1 ng/mL; IQR 7.1-75.0 ng/mL versus median 7.2 ng/mL; IQR 5.9-23.1 ng/mL; p = 0.008). There was a strong positive correlation between sST2 and IL-10 in neonates with funisitis and/or FIRS (Spearman's Rho = 0.7, p < 0.0001).

CONCLUSION

FIRS and funisitis are associated with an elevation of umbilical cord plasma concentrations of soluble ST2. This protein represents an important mediator of the immune response in neonates diagnosed with FIRS by promoting an anti-inflammatory effect in association with IL-10.

Perinatal immunoproteins predict the risk of cerebral palsy in preterm children

OBJECTIVE

To investigate whether blood cytokines during the perinatal period predict the risk of cerebral palsy (CP) in preterm infants.

METHODS

This prospective cohort study comprised 169 children born before 32 weeks of gestation. Cord blood was drawn at birth, and 109 cytokines were analyzed using microarrays. Eleven cytokines were further measured from both cord and peripheral blood on days 1 and 7. Cerebral palsy was confirmed at 5 years of age.

RESULTS

Cerebral palsy was diagnosed in 19 children. Five clusters of cord blood cytokines were scored using factor analysis. According to logistic regression analysis, the scores of factors 1 and 2 independently predicted the risk of CP. These cytokines included several growth factors and chemokines, and they all tended to be higher in children with CP than in children without CP. Inflammatory cytokine levels were associated with CP risk on days 1 and 7 after birth.

CONCLUSION

The high blood concentrations of various cytokines during the perinatal period may relate to CP, and these cytokines may influence the pathways leading to early insult in the central nervous system. The risk profile of inflammatory cytokines is different at birth than during the first week after birth.

Unrecognized viral respiratory tract infections in premature infants during their birth hospitalization: a prospective surveillance study in two neonatal intensive care units

OBJECTIVE

To determine the frequency and effects of nosocomial respiratory viral infections (RVIs) in premature neonates, including those who may be asymptomatic.

STUDY DESIGN

We performed a year-long surveillance for RVIs in infants <33 weeks gestational age admitted to 2 Syracuse neonatal intensive care units. Infants were enrolled within 3 days of neonatal intensive care unit admission and were sampled for RVIs until discharge using a multiplex polymerase chain reaction assay capable of detecting 17 different respiratory viruses or subtypes.

RESULTS

Twenty-six of 50 prematurely born infants (52%) tested positive for a respiratory virus at least once during their birth hospitalization. Testing positive for a respiratory virus was significantly associated with longer length of stay (70 days vs 35 days, P = .002) and prolonged ventilatory support (51 vs 13 days, P = .002). Infants who tested positive for a respiratory virus during their birth hospitalization had more than twice the rate of developing bronchopulmonary dysplasia (P < .05).

CONCLUSION

Nosocomial RVIs were frequent in our study population, despite the absence of clinical indicators of illness. Length of hospital stay was significantly longer and a diagnosis of bronchopulmonary dysplasia was more common in infants who had respiratory viruses detected.

Choriodecidual infection downregulates angiogenesis and morphogenesis pathways in fetal lungs from Macaca nemestrina

BACKGROUND

Intrauterine exposure to amniotic fluid (AF) cytokines is thought to predispose to bronchopulmonary dysplasia (BPD). We evaluated the effects of GBS exposure on RNA expression in fetal lung tissue to determine early molecular pathways associated with fetal lung injury that may progress to BPD.

METHODS

Ten chronically catheterized pregnant monkeys (Macaca nemestrina) at 118-125 days gestation (term = 172 days) received choriodecidual inoculation of either: 1) Group B Streptococcus (n = 5) or 2) saline (n = 5). Cesarean section and fetal necropsy was performed in the first week after GBS or saline inoculation regardless of labor. RNA was extracted from fetal lungs and profiled by microarray. Results were analyzed using single gene, Gene Set, and Ingenuity Pathway Analysis. Validation was by RT-PCR and immunohistochemistry.

RESULTS

Despite uterine quiescence in most cases, fetal lung injury occurred in four GBS cases (intra-alveolar neutrophils, interstitial thickening) and one control (peri-mortem hemorrhage). Significant elevations of AF cytokines (TNF-α, IL-8, IL-1β, IL-6) were detected in GBS versus controls (p<0.05). Lung injury was not directly caused by GBS, because GBS was undetectable by culture and PCR in the AF and fetal lungs. A total of 335 genes were differentially expressed greater than 1.5 fold (p<0.05) with GBS exposure associated with a striking upregulation of genes in innate and adaptive immunity and downregulation of pathways for angiogenesis, morphogenesis, and cellular growth and development.

CONCLUSIONS

A transient choriodecidual infection may induce fetal lung injury with profound alterations in the genetic program of the fetal lung before signs of preterm labor. Our results provide a window for the first time into early molecular pathways disrupting fetal lung angiogenesis and morphogenesis before preterm labor occurs, which may set the stage for BPD. A strategy to prevent BPD should target the fetus in utero to attenuate alterations in the fetal lung genetic program.

A new way of thinking about complications of prematurity

The morbidity and mortality of preterm infants are impacted by their ability to maintain physiologic homeostasis using metabolic, endocrine, and immunologic mechanisms independent of the mother's placenta. Exploring McEwen's allostatic load model in preterm infants provides a new way to understand the altered physiologic processes associated with frequently occurring complications of prematurity such as bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis, and retinopathy of prematurity. The purpose of this article is to present a new model to enhance understanding of the altered physiologic processes associated with complications of prematurity. The model of allostatic load and complications of prematurity was derived to explore the relationship between general stress of prematurity and complications of prematurity. The proposed model uses the concepts of general stress of prematurity, allostasis, physiologic response patterns (adaptive-maladaptive), allostatic load, and complications of prematurity. These concepts are defined and theoretical relationships in the proposed model are interpreted using the four maladaptive response patterns of repeated hits, lack of adaptation, prolonged response, and inadequate response. Empirical evidence for cortisol, inflammation, and oxidative stress responses are used to support the theoretical relationships. The proposed model provides a new way of thinking about physiologic dysregulation in preterm infants. The ability to describe and understand complex physiologic mechanisms involved in complications of prematurity is essential for research. Advancing the knowledge of complications of prematurity will advance clinical practice and research and lead to testing of interventions to reduce negative outcomes in preterm infants.