Relation of exhaled nitric oxide levels to development of bronchopulmonary dysplasia

The association of exhaled nitric oxide with air pollutants in young infants of asthmatic mothers

BACKGROUND

Exhaled nitric oxide is a marker of airway inflammation. Air pollution induces airway inflammation and oxidative stress. Little is known about the impact of air pollution on exhaled nitric oxide in young infants.

METHODS

The Breathing for Life Trial recruited pregnant women with asthma into a randomised controlled trial comparing usual clinical care versus inflammometry-guided asthma management in pregnancy. Four hundred fifty-seven infants from the Breathing for Life Trial birth cohort were assessed at six weeks of age. Exhaled nitric oxide was measured in unsedated, sleeping infants. Its association with local mean 24-h and mean seven-day concentrations of ozone, nitric oxide, nitrogen dioxide, carbon monoxide, sulfur dioxide, ammonia, particulate matter less than 10 μm (PM10) and less than 2.5 μm (PM2.5) in diameter was investigated. The air pollutant data were sourced from local monitoring sites of the New South Wales Air Quality Monitoring Network. The association was assessed using a 'least absolute shrinkage and selection operator' (LASSO) approach, multivariable regression and Spearman's rank correlation.

RESULTS

A seasonal variation was evident with higher median exhaled nitric oxide levels (13.6 ppb) in warmer months and lower median exhaled nitric oxide levels (11.0 ppb) in cooler months, P = 0.008. LASSO identified positive associations for exhaled nitric oxide with 24-h mean ammonia, seven-day mean ammonia, seven-day mean PM10, seven-day mean PM2.5, and seven-day mean ozone; and negative associations for eNO with seven-day mean carbon monoxide, 24-h mean nitric oxide and 24-h mean sulfur dioxide, with an R-square of 0.25 for the penalized coefficients. These coefficients selected by LASSO (and confounders) were entered in multivariable regression. The achieved R-square was 0.27.

CONCLUSION

In this cohort of young infants of asthmatic mothers, exhaled nitric oxide showed seasonal variation and an association with local air pollution concentrations.

Exhaled Volatile Organic Compounds for Early Prediction of Bronchopulmonary Dysplasia in Infants Born Preterm

OBJECTIVE(S)

To investigate the predictive performances of exhaled breath volatile organic compounds (VOCs) for development of bronchopulmonary dysplasia (BPD) in infants born preterm.

METHODS

Exhaled breath was collected from infants born <30 weeks' gestation at days 3 and 7 of life. Ion-fragments detected by gas-Chromatography-mass-spectrometry analysis were used to derive and internally validate a VOC prediction model for moderate or severe BPD at 36 weeks postmenstrual age. We tested the predictive performance of the National Institute of Child Health and Human Development (NICHD) clinical BPD prediction model with and without VOCs.

RESULTS

Breath samples were collected from 117 infants (mean gestation 26.8 [±1.5] weeks). Thirty-three percent of the infants developed moderate or severe BPD. The VOC model showed a c-statistic of 0.89 (95% confidence interval [CI] 0.80-0.97) and 0.92 (95% CI 0.84-0.99)) for the prediction of BPD at days 3 and 7, respectively. Adding the VOCs to the clinical prediction model in non-invasive supported infants resulted in significant improvement in discriminative power on both days (day 3: c-statistic 0.83 versus 0.92, p-value 0.04; day 7: c-statistic 0.82 versus 0.94, p-value 0.03).

CONCLUSIONS

This study showed that VOC profiles in exhaled breath of preterm infants on non-invasive support in the first week of life differ between those developing and not developing BPD. Adding VOCs to a clinical prediction model significantly improved its discriminative performance.

Cohort profile: the vitamin A and D and nitric oxide (AD-ON) observational cohort on lung development and symptoms in premature and mature children in North Zealand, Denmark

PURPOSE

The risk of developing asthma-like symptoms and asthma in childhood is influenced by genetics, environmental exposures, prenatal and early postnatal events, and their interactions. The cohort name refers to vitamins A and D, and nitric oxide (NO) spelt backwards and this cohort profile paper aims to present the data collection and aim of the cohort.The overall aim when establishing this cohort was to investigate if childhood lung function can be traced back to early neonatal lung function and fractional exhaled NO (FeNO) and investigate prenatal and postnatal risk factors including maternal and neonatal vitamin A and D levels in preterm and term born children.

PARTICIPANTS

One thousand five hundred women and their babies born at Nordsjaellands Hospital in Denmark from 2013 to 2014 were included in the AD-ON research biobank prior to birth.Neonates from the AD-ON research biobank, admitted to the Neonatal Intensive Care Unit at Nordsjaellands Hospital, were included in the AD-ON neonatal cohort. The neonatal cohort consisted of 149 neonates hereof 63 preterm and 86 term born. The children in the cohort have been invited to follow-up visits at age 1 and 6 years.

FINDINGS TO DATE

Published data from this cohort includes a validated and clinically applicable method to measure FeNO in neonates. We found an age-specific pattern of association between respiratory symptoms at age 1 and neonatal FeNO in preterm children. Moreover, we found that the respiratory symptoms risk was associated with postnatal factors (Respiratory Syncytial Virus infection and parental smoking) in preterm infants and prenatal factors (parental asthma and maternal infection during pregnancy) in term born infants.

FUTURE PLANS

In the future, the children will be examined continuously with 3-year to 5-year intervals until the age of 18. Lung function, allergy tests, environmental exposure measurements and questionnaires will be collected at each follow-up visit.

Neonatal FeNO, risk factors, and respiratory morbidity in infants: A cohort study

BACKGROUND

Respiratory symptoms in infancy are more common in premature infants. Nitric oxide (NO) is involved in prenatal and neonatal lung development. Measurement of exhaled NO is easy and well-tolerated by neonates. We investigated whether neonatal exhaled NO can be used to predict subsequent respiratory symptoms. Furthermore, we sought to determine prenatal and postnatal factors associated with increased respiratory symptom risk during the first year of life in premature and mature infants.

METHODS

Tidal fractional exhaled NO (FeNO) was measured in a birth cohort (n = 135) of premature and mature infants, up to six times during the first month of life. Primary outcomes were troublesome respiratory symptoms (TRS) and doctor-diagnosed asthmatic bronchitis (AB) at 1 year of age.

FINDINGS

The correlation between FeNO and TRS changed significantly in an age-dependent pattern in moderately premature infants (p = .02). Moderately premature infants with a low FeNO of 2 ppb on postnatal Day 3 had a 48% (95% confidence interval [CI]: 17%-80%) probability of TRS, compared with a probability of 12% (95% CI: 1%-64%) for otherwise similar infants with a FeNO of 11 ppb. Respiratory syncytial virus infection and parental smoking significantly increased the TRS risk in premature infants. Parental asthma and maternal antibiotic use during pregnancy significantly increased the TRS risk in mature infants.

INTERPRETATION

An age-specific association between neonatal FeNO and respiratory symptoms was seen in moderately premature infants. TRS risk was associated with postnatal factors in premature and prenatal factors in mature infants.

Cytokines and Exhaled Nitric Oxide Are Risk Factors in Preterm Infants for Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is the most common complication of extremely preterm birth. This study was aimed at detecting cytokine and fractional exhaled nitric oxide (FeNO) levels to evaluate their mechanisms and predicted significance for BPD. Preterm infants born at gestational age ≤ 32 weeks were recruited, and clinical data were collected. We detected ten cytokines, including IFN-γ, IL-10, IL-12p70, IL-13, IL-1β, IL-2, IL-4, IL-6, IL-8, and TNF-α on Days 1–3, Days 7–14, and Days 21–28 after birth by using the Meso Scale Discovery (MSD) technology. The FeNO levels of infants were measured when they met the discharge criteria. A total of 46 preterm infants were enrolled, consisting of 14 infants in BPD group and 32 infants in the control group. The gestational age (27.5 ± 1.3 vs. 29.9 ± 1.3 weeks) and birth weight (1021 ± 261 g vs. 1489 ± 357 g) were lower in the BPD group. The following were high-risk factors for BPD, as determined by multivariate logistic regression analysis: gestational age < 30 weeks, birth weight < 1000 g, PDA, longer mechanical ventilation, and higher FeNO. The cytokines of IL-6 and IL-8 on Days 7–14 and IL-4, IL-6, IL-8, and TNF-α on Days 21–28 were also high-risk factors for BPD. IL-6 contributed to BPD disease severity. Conclusion. The preterm infants with PDA and prolonged mechanical ventilation tended to develop BPD. The IL-6 and IL-8 were significantly increased on Days 7–14 and were high-risk factors for BPD. Moreover, the IL-6 level was associated with BPD disease severity. We speculated that NO was related to BPD via Th2 cell-mediated inflammatory responses such as IL-4 and IL-6. Cytokines might predict the occurrence of BPD.

Bronchopulmonary dysplasia

In the absence of effective interventions to prevent preterm births, improved survival of infants who are born at the biological limits of viability has relied on advances in perinatal care over the past 50 years. Except for extremely preterm infants with suboptimal perinatal care or major antenatal events that cause severe respiratory failure at birth, most extremely preterm infants now survive, but they often develop chronic lung dysfunction termed bronchopulmonary dysplasia (BPD; also known as chronic lung disease). Despite major efforts to minimize injurious but often life-saving postnatal interventions (such as oxygen, mechanical ventilation and corticosteroids), BPD remains the most frequent complication of extreme preterm birth. BPD is now recognized as the result of an aberrant reparative response to both antenatal injury and repetitive postnatal injury to the developing lungs. Consequently, lung development is markedly impaired, which leads to persistent airway and pulmonary vascular disease that can affect adult lung function. Greater insights into the pathobiology of BPD will provide a better understanding of disease mechanisms and lung repair and regeneration, which will enable the discovery of novel therapeutic targets. In parallel, clinical and translational studies that improve the classification of disease phenotypes and enable early identification of at-risk preterm infants should improve trial design and individualized care to enhance outcomes in preterm infants.

Tidal breath eNO measurements in a cohort of unsedated hospitalized neonates-A method validation

AIM

Exhaled Nitric oxide (eNO) is an inflammatory marker. In 2002 Hall et al. [J Appl Physiol. 92:59-66] established an infant eNO measurement method, fulfilling four criteria of feasibility: simple, non-invasive, without impact on the natural breathing pattern, and accounting for flow by NO output (V'NO). Although tidal breathing is accepted as an eNO measurement method in uncooperative patients, it is seldom used outside research labs. The variability and lack of validated methods have restrained from exploring the area in preterm and term neonates the last years. This study aimed to validate clinically feasible longitudinal online tidal eNO and V'NO in a real-life birth cohort of un-sedated, hospitalized preterm, and term neonates.

METHOD

We included 149 newborns, GA 28-42 weeks. Each scheduled for six repeated, non-invasive, on-line eNO measurements with Ecomedics CLD 88sp and NO-free air. We used three 60-second-eNO measurements. The method was adapted to fit preterm and term neonates with unstable respiration, without excluding sighs and surrounding breaths.

RESULT

Protocol measurements with a maximum mutual difference of 1 ppb succeeded in 85-99%, increasing with postnatal age. We performed mixed model analyses in three hierarchical measurement levels. Despite the irregular breathing of newborns, the predictions of individual eNO levels in the average infant was a 0.05 SD. Exhaled NO was flow-dependent (P = 0.028); V'NO but not eNO was associated with preterm birth (P < 0.001) and >24 h CPAP treatment (P = 0.0316).

CONCLUSION

We validated clinically, non-invasive, online eNO measurements in neonates. The method was well tolerated and exhibited low subject-specific-prediction-variance and high success rates.

Development of severe bronchopulmonary dysplasia is associated with alterations in fecal volatile organic compounds

BackgroundThe aim of this study was to evaluate the potential of fecal volatile organic compounds (VOCs), obtained by means of an electronic nose device (Cyranose 320), as early non-invasive biomarker for BPD.MethodsIn this nested case-control study performed at three Neonatal Intensive Care Units, fecal samples obtained at postnatal age of 7, 14, 21, and 28 days from preterm infants with severe bronchopulmonary dysplasia (BPD) were compared with fecal VOC profiles from matched controls. Microbiota analysis was performed by means of IS-pro technique on fecal samples collected at 28 days postnatally.ResultsVOC profiles of infants developing severe BPD (n=15) could be discriminated from matched controls (n=15) at postnatal age of 14 days (area under the curve (±95% confidence interval), P-value, sensitivity, specificity; 0.72 (0.54-0.90), 0.040, 60.0%, 73.3%), 21 days (0.71 (0.52-0.90), 0.049, 66.7%, 73.3%) and 28 days (0.77 (0.59-0.96), 0.017, 69.2%, 69.2%) but not at 7 days. Intestinal microbiota did not differ between BPD subjects and controls.ConclusionFecal VOC profiles of infants developing BPD could be differentiated from controls at postnatal day 14, 21, and 28. VOC differences could not be directed to intestinal microbiota alterations but presumably reflect local and systemic metabolic and inflammatory pathways associated with BPD.

Differences and similarities between bronchopulmonary dysplasia and asthma in schoolchildren

BACKGROUND

The long-term respiratory characteristics of ex-preterm children with bronchopulmonary dysplasia (BPD) are not established. The objective of this study was to describe hallmarks of BPD at school age in comparison to children with atopic asthma.

METHODS

This study was a cross-sectional descriptive comparative study in a hospital-based setting. Thirty schoolchildren diagnosed with BPD (10.4 years/born at 26.6 weeks' gestation) and 30 age- and sex-matched children with asthma and sensitized to airborne allergens (IgE >0.35 kU_A /L) were analyzed. Measurements included fraction of exhaled nitric oxide (FENO, ppb), dynamic and static lung function, and bronchial provocation with methacholine (PD:20) and mannitol (PD:15), as well as an evaluation of respiratory symptoms using the asthma control test (C-ACT).

RESULTS

Lung function measures (FEV1% 77 vs 84, FEV1/FVC% 85 vs 91, FEF50% 61 vs 80) and carbon monoxide diffusion capacity (DLCO%, 81 vs 88) were all reduced in children with BPD compared to asthma (P values <0.042). FENO values were also significantly lower in children with BPD (12 vs 23, P = 0.019). The proportion of positive methacholine tests (74% vs 93%, P = 0.14) was comparable between BPD and asthma. However, less responsiveness towards mannitol (19% vs 61%, P = 0.007) and fewer self-reported symptoms (C-ACT, median 26 vs 24, P = 0.003) were found in the BPD group.

CONCLUSION

Respiratory hallmarks of BPD at school-age were reduced lung function, limited responsiveness towards indirectly acting mannitol but hyper-responsiveness towards direct acting methacholine and impairment in diffusion capacity. Children with BPD displayed less evidence of airway inflammation compared with atopic asthma.

Biomarkers, Early Diagnosis, and Clinical Predictors of Bronchopulmonary Dysplasia

The pathogenesis of bronchopulmonary dysplasia (BPD) is multifactorial, and the clinical phenotype of BPD is extremely variable. Several clinical and laboratory biomarkers have been proposed for the early identification of infants at higher risk of BPD and for determination of prognosis of infants with a diagnosis of BPD. The authors review available literature on prediction tools and biomarkers of BPD, using clinical variables and biomarkers based on imaging, lung function measures, and measurements of various analytes in different body fluids that have been determined to be associated with BPD either in a targeted manner or by unbiased omic profiling.

Application of nitric oxide measurements in clinical conditions beyond asthma

Fractional exhaled nitric oxide (FeNO) is a convenient, non-invasive method for the assessment of active, mainly Th2-driven, airway inflammation, which is sensitive to treatment with standard anti-inflammatory therapy. Consequently, FeNO serves as a valued tool to aid diagnosis and monitoring in several asthma phenotypes. More recently, FeNO has been evaluated in several other respiratory, infectious, and/or immunological conditions. In this short review, we provide an overview of several clinical studies and discuss the status of potential applications of NO measurements in clinical conditions beyond asthma.

Inflammatory activity at school age in very low birth weight bronchopulmonary dysplasia survivors

OBJECTIVE

Airway inflammation is involved in the pathogenesis of bronchopulmonary dysplasia (BPD). The aim of the study was to evaluate the inflammatory activity in plasma and exhaled air in very low birth weight (VLBW) BPD survivors at school age.

METHODS

Twenty-one 6-14-year-old former VLBW (birth weight ≤1,500 g) children with severe radiographic BPD (radBPD), 19 without radBPD (nonBPD group) and 19 non-asthmatic term controls underwent measurement of eosinophil cationic protein, IL-6, IL-8, adiponectin, adipsin, leptin, and resistin in plasma, leukotriene B4 and 8-isoprostane in exhaled breath condensate, and NO in exhaled breath. Background data were obtained from patient records, clinical examination and parental questionnaire. Both univariate and multivariate models were applied in the statistical analysis.

RESULTS

There were no significant differences between the groups in any of the inflammatory markers measured. Five (25%) radBPD and 2 (11%) nonBPD children reported asthma (P = 0.058). In logistic regression analysis, exposure to chorioamnionitis was associated with low IL-8 (OR 29.0, 95% CI 3.27-258) and postnatal corticosteroid therapy with high adiponectin (OR 32.0, 95% CI 1.29-793). High body mass index standard deviation score (BMI-SDS) was associated with high plasma adipsin (OR 2.47, 95% CI 1.07-5.75) and leptin (OR 5.76, 95%CI 1.83-18.2) levels.

CONCLUSIONS

The inflammatory activity seems to decrease by school age in VLBW BPD survivors. Chorioamnionitis and postnatal corticosteroid treatment may modulate the inflammatory responsiveness in VLBW subjects even up to school age. The respiratory outcome in VLBW infants might be improved by preventing excessive weight gain.

The role of poly(ADP-ribose) polymerase-1 inhibitor in carrageenan-induced lung inflammation in mice

Increasing indication is unveiling a role for poly(ADP-ribose) polymerase (PARP)-1 in the regulation of inflammatory/immune responses. The aim of the present study was to determine the potential anti-inflammatory effects of PARP-1 inhibitor 5-aminoisoquinolinone (5-AIQ) to explore the role of PARP-1 inhibitor in a mouse model of carrageenan-induced lung inflammation. A single dose of 5-AIQ (1.5mg/kg) was administered intraperitoneally (i.p.) 1h before λ-carrageenan (Cg) administration. We assessed the effects of 5-AIQ treatment on CD25(+), GITR(+), CD25(+)GITR(+), IL-17(+) and Foxp3(+) cells which were investigated using flowcytometry in pleural exudates and heparinized blood. We also evaluated mRNA expressions of IL-6, TNF-α, IL-1β, IL-10, CD11a, l-selectin (CD62L), ICAM-1, MCP-1, iNOS and COX-2 in the lung tissue. We further examined the effects of 5-AIQ on the key mediators of inflammation, namely COX-2, STAT-3, NF-kB p65, PARP-1, IkB-α and IL-4 protein expression in the lung tissue using western blotting. The results illustrated that the numbers of T cell subsets, IL-17(+) cytokine levels were markedly increased and Foxp3(+) production decreased in the Cg group. Furthermore, Cg-induced up-regulation of adhesion molecules, pro-inflammatory mediators and chemokine expressions. Western blot analysis revealed an increased protein expressions of COX-2, STAT-3 NF-kB p65 and PARP-1 and decreased IkB-α and IL-4 in the Cg group. PARP-1 inhibitor via 5-AIQ treatment reverses the action significantly of all the previously mentioned effects. Moreover, histological examinations revealed anti-inflammatory effects of 5-AIQ, whereas Cg-group aggravated Cg-induced inflammation. Present findings demonstrate the potent anti-inflammatory action of the PARP-1 inhibitor in acute lung injury induced by carrageenan.

Exhaled nitric oxide in neonates with or without hypoxemic respiratory failure

BACKGROUND

Exhaled nitric oxide (eNO) is one of the airway condensate derived markers, reflecting mainly airway inflammation in asthma and other lung diseases. The changes of eNO levels as pathophysiology of neonatal hypoxemic respiratory failure (HRF) in early postnatal life have not been thoroughly studied. The present study was to establish a method for measuring eNO concentrations in neonates with or without HRF.

METHODS

Twenty-two newborn infants with HRF and 26 non-NRF controls were included within the first 24 hours of postnatal life. Their eNO levels were detected with a rapid-response chemiluminescence analyzer daily during the first week of their postnatal life, and lung mechanics and gas exchange efficiency were monitored at the same time, such as pulse oxygen saturation (SpO2), inspired fraction of oxygen (FiO2) and other parameters.

RESULTS

During the first two days of postnatal life, eNO values of HRF neonates were significantly higher than those of the control neonates (day 1, 7.9±3.2 vs. 5.8±1.8 parts per billion [ppb], P<0.05; day 2, 8.8±3.2 vs. 6.0±2.4 ppb, P<0.05), but there were no significant differences in the following days. With SpO2/FiO2 increasing, difference of eNO values between the HRF and non-HRF neonates became narrowed, but there was still a two-fold difference of eNO/[SpO2/(FiO2×100)] on days 5-7.

CONCLUSION

We established a method for measuring eNO and found difference in neonates with or without HRF, which diminished with prolonged postnatal days, reflecting pathophysiological characteristics of HRF.

Effect of intubation and mechanical ventilation on exhaled nitric oxide in preterm infants with and without bronchopulmonary dysplasia measured at a median postmenstrual age of 49 weeks

Background

Exhaled nitric oxide (eNO) is a marker of established airway inflammation in adults and children, but conflicting results have been reported in preterm infants when postnatal eNO is measured during tidal breathing. This study investigated the extent to which intubation and mechanical ventilation (MV) affect eNO and NO production (V’_NO) in preterm infants with and without bronchopulmonary dysplasia (BPD).

Patients and methods

A total of 176 very low birth weight (VLBW) infants (birth weight <1500 g), including 74 (42%) with and 102 (58%) without BPD, were examined at a median postmenstrual age of 49 weeks. Of the 176 infants, 84 (48%) did not require MV, 47 (27%) required MV for <7 days and 45 (26%) required MV for ≥7 days. Exhaled NO and tidal breathing parameters were measured in sleeping infants during tidal breathing, respiratory mechanics were assessed by occlusion tests, and arterialized capillary blood gas was analyzed.

Results

eNO was significantly correlated with tidal breathing parameters, while V’_NO was correlated with growth parameters, including age and body length (p < 0.001 each). Infants who were intubated and received MV for <7 days had significantly lower eNO (p < 0.01) and V’_NO (p < 0.01) than non-ventilated infants. In contrast, eNO and V’_NO did not differ significantly in non-ventilated infants and those receiving MV for ≥7 days. Multivariate analysis showed that independent on the duration of MV eNO (p = 0.003) and V’_NO (p = 0.018) were significantly increased in BPD infants comparable with the effects of intubation and MV on eNO (p = 0.002) and V’_NO (p = 0.017).

Conclusions

Preterm infants with BPD show only weak postnatal increases in eNO and V’_NO, but these changes may be obscured by the distinct influences of breathing pattern and invasive respiratory support. This limits the diagnostic value of postnatal eNO measurements in the follow-up of BPD infants.

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.

Very low birth weight and respiratory outcome: association between airway inflammation and hyperresponsiveness

BACKGROUND

The respiratory outcomes after preterm birth have changed, and it is unclear whether increased airway hyperresponsiveness (AHR) later in childhood is associated with airway inflammation.

OBJECTIVE

To investigate the association between AHR and fractional exhaled nitric oxide (FeNO), including the alveolar concentration of nitric oxide, in school-age children with very low birth weight (VLBW).

METHODS

Twenty-nine children with VLBW, 33 children with a history of early wheeze, and 60 healthy controls underwent a FeNO measurement and bronchial challenge test with histamine. Atopy was assessed with skin prick tests.

RESULTS

Children with VLBW had well-preserved baseline lung function but significantly increased AHR, expressed as the dose response slope (P < .001). Geometric mean FeNO levels were similar between VLBW children and healthy controls, and a history of bronchopulmonary dysplasia had no effect. In the VLBW and early wheeze groups, AHR was associated with FeNO (r = 0.47, P = .01, and r = 0.43, P = .013, respectively), but in a stratified analysis, this association was significant only in atopic individuals. By using the multiple flow FeNO technique, the bronchial nitric oxide flux rather than alveolar nitric oxide concentrations were associated with AHR in both children with early wheeze and VLBW.

CONCLUSION

We conclude that in VLBW children AHR is related to FeNO but only in atopic individuals. Similar to children with early wheeze, this association is dependent on bronchial flux rather than alveolar nitric oxide concentration. It is likely that AHR is modified by atopic inflammation rather than by inflammatory process due to prematurity.

Anti-inflammatory effects of adrenomedullin on acute lung injury induced by Carrageenan in mice

Adrenomedullin (AM) is a 52 amino acid peptide that has shown predominant anti-inflammatory activities. In the present study, we evaluated the possible therapeutic effect of this peptide in an experimental model of acute inflammation, the carrageenan- (CAR-) induced pleurisy. Pleurisy was induced by injection of CAR into the pleural cavity of mice. AM (200 ng/kg) was administered by intraperitoneal route 1 h after CAR, and the animals were sacrificed 4 h after that. AM treatment attenuated the recruitment of leucocytes in the lung tissue and the generation and/or the expression of the proinflammatory cytokines as well as the expression of the intercellular cell adhesion molecules. Moreover, AM inhibited the induction of inducible nitric oxide synthase (iNOS), thereby abating the generation of nitric oxide (NO) and prevented the oxidative and nitroxidative lung tissue injury, as shown by the reduction of nitrotyrosine, malondialdehyde (MDA), and poly (ADP-ribose) polymerase (PARP) levels. Finally, we demonstrated that these anti-inflammatory effects of AM were associated with the inhibition of nuclear factor-κB (NF-κB) activation. All these parameters were markedly increased by intrapleural CAR in the absence of any treatment. We report that treatment with AM significantly reduces the development of acute lung injury by downregulating a broad spectrum of inflammatory factors.

Targeting inflammation to prevent bronchopulmonary dysplasia: can new insights be translated into therapies?

Bronchopulmonary dysplasia (BPD) frequently complicates preterm birth and leads to significant long-term morbidity. Unfortunately, few therapies are known to effectively prevent or treat BPD. Ongoing research has been focusing on potential therapies to limit inflammation in the preterm lung. In this review we highlight recent bench and clinical research aimed at understanding the role of inflammation in the pathogenesis of BPD. We also critically assess currently used therapies and promising developments in the field.

Impact of chorioamnionitis on exhaled nitric oxide and endotracheal aspirate levels of nitrites-nitrates and interleukin-8 in mechanically ventilated preterm neonates

OBJECTIVES

To assess the influence of maternal chorioamnionitis on early exhaled nitric oxide (NO) and levels of nitrites-nitrates and interleukin (IL)-8 in endotracheal aspirate fluid in mechanically ventilated preterm neonates.

STUDY DESIGN

Cross-sectional study. PATIENT-SUBJECT SELECTION: Between September 2007 and August 2009, 54 mechanically ventilated preterm neonates were included. Patients were divided into two groups according to the presence or absence of maternal chorioamnionitis, and those without chorioamnionitis (controls) were further stratified into two subgroups by birth weight < or ≥ 2,000 g.

METHODOLOGY

The ventilator used was a Babylog 8000. The NO level assessed was the plateau value given by the software of the Sievers NOA apparatus. Collection of endotracheal aspirate fluid samples was performed coinciding with routine aspirations and using the dry technique.

RESULTS

The two groups of control neonates showed statistically significant differences in exhaled NO expressed as nl/min and normalized exhaled NO expressed as either nl/min or nl/min/kg, so they are not homogeneous and cannot be used in clinical practice. Serum C-reactive protein and endotracheal aspirate levels of nitrites-nitrates were significantly higher in the chorioamnionitis group than in controls (3.6 vs. 1.07 µmol/L; P = 0.035). Nitrites-nitrates levels were positively correlated with exhaled NO in ppb (ρ = 0.367; P = 0.006). Minute exhaled endogenous NO was significantly higher in the chorioamnionitis group (0.48 vs. 0.27 nl/min/kg; P = 0.021).

CONCLUSIONS

In mechanically ventilated preterm infants weighing <2,000 g, maternal chorioamnionitis was associated with an increase of early exhaled NO (nl/min/kg) and serum levels of C-reactive protein and levels of nitrites-nitrates in endotracheal aspirate fluid.