Catherine L. Gangell

Lung Disease at Diagnosis in Infants with Cystic Fibrosis Detected by Newborn Screening

RATIONALE The promise of newborn screening (NBS) for cystic fibrosis (CF) has not been fully realized, and the extent of improvement in respiratory outcomes is unclear. We hypothesized that significant lung disease was present at diagnosis. OBJECTIVES To determine the extent of lung disease in a geographically defined population of infants with CF diagnosed after detection by NBS. METHODS Fifty-seven infants (median age, 3.6 mo) with CF underwent bronchoalveolar lavage and chest computed tomography (CT) using a three-slice inspiratory and expiratory protocol. MEASUREMENTS AND MAIN RESULTS Despite the absence of respiratory symptoms in 48 (84.2%) of infants, a substantial proportion had lung disease with bacterial infection detected in 12 (21.1%), including Staphylococcus aureus (n = 4) and Pseudomonas aeruginosa (n = 3); neutrophilic inflammation (41. 4 x 10(3) cells/ml representing 18.7% of total cell count); proinflammatory cytokines, with 44 (77.2%) having detectable IL-8; and 17 (29.8%) having detectable free neutrophil elastase activity. Inflammation was increased in those with infection and respiratory symptoms; however, the majority of those infected were asymptomatic. Radiologic evidence of structural lung disease was common, with 46 (80.7%) having an abnormal CT; 11 (18.6%) had bronchial dilatation, 27 (45.0%) had bronchial wall thickening, and 40 (66.7%) had gas trapping. On multivariate analysis, free neutrophil elastase activity was associated with structural lung disease. Most children with structural lung disease had no clinically apparent lung disease. CONCLUSIONS These data support the need for full evaluation in infancy and argue for new treatment strategies, especially those targeting neutrophilic inflammation, if the promise of NBS for CF is to be realized.

Bronchiectasis in Infants and Preschool Children Diagnosed with Cystic Fibrosis after Newborn Screening

OBJECTIVES To determine the prevalence of bronchiectasis in young children with cystic fibrosis (CF) diagnosed after newborn screening (NBS) and the relationship of bronchiectasis to pulmonary inflammation and infection. STUDY DESIGN Children were diagnosed with CF after NBS. Computed tomography and bronchoalveolar lavage were performed with anesthesia (n = 96). Scans were analyzed for the presence and extent of abnormalities. RESULTS The prevalence of bronchiectasis was 22% and increased with age (P = .001). Factors associated with bronchiectasis included absolute neutrophil count (P = .03), neutrophil elastase concentration (P = .001), and Pseudomonas aeruginosa infection (P = .03). CONCLUSIONS Pulmonary abnormalities are common in infants and young children with CF and relate to neutrophilic inflammation and infection with P. aeruginosa. Current models of care for infants with CF fail to prevent respiratory sequelae. Bronchiectasis is a clinically relevant endpoint that could be used for intervention trials that commence soon after CF is diagnosed after NBS.

Progression of early structural lung disease in young children with cystic fibrosis assessed using CT

Background Cross-sectional studies implicate neutrophilic inflammation and pulmonary infection as risk factors for early structural lung disease in infants and young children with cystic fibrosis (CF). However, the longitudinal progression in a newborn screened population has not been investigated. Aim To determine whether early CF structural lung disease persists and progresses over 1 year and to identify factors associated with radiological persistence and progression. Methods 143 children aged 0.2–6.5 years with CF from a newborn screened population contributed 444 limited slice annual chest CT scans for analysis that were scored for bronchiectasis and air trapping and analysed as paired scans 1 year apart. Logistic and linear regression models, using generalised estimating equations to account for multiple measures, determined associations between persistence and progression over 1 year and age, sex, severe cystic fibrosis transmembrane regulator (CFTR) genotype, pancreatic sufficiency, current respiratory symptoms, and neutrophilic inflammation and infection measured by bronchoalveolar lavage. Results Once detected, bronchiectasis persisted in 98/133 paired scans (74%) and air trapping in 178/220 (81%). The extent of bronchiectasis increased in 139/227 (63%) of paired scans and air trapping in 121/264 (47%). Radiological progression of bronchiectasis and air trapping was associated with severe CFTR genotype, worsening neutrophilic inflammation and pulmonary infection. Discussion CT-detected structural lung disease identified in infants and young children with CF persists and progresses over 1 year in most cases, with deteriorating structural lung disease associated with worsening inflammation and pulmonary infection. Early intervention is required to prevent or arrest the progression of structural lung disease in young children with CF.

Acquisition and eradication of P. aeruginosa in young children with cystic fibrosis

When do infants and young children with cystic fibrosis acquire infection with Pseudomonas aeruginosa? Can this be eradicated when first detected? Children <6 yrs of age participated in an annual bronchoalveolar lavage (BAL)-based microbiological surveillance programme in Perth, Australia. When P. aeruginosa was detected, an eradication programme using combination treatment with i.v., oral and nebulised antibiotics was undertaken. Repeat BAL was performed 3 months following treatment, to assess eradication success. P. aeruginosa was detected in 33 (28.4%) children; median (range) age at detection was 30.5 (3.3–71.4) months. P. aeruginosa was mucoid at detection in six (18.2%) out of 33 patients and associated with respiratory symptoms in 16 (48.5%) out of 33 children. In total, 26 children underwent eradication therapy, with P. aeruginosa eradicated in 20 (77%) out of 26 following one eradication cycle and in three (total 88%) additional children following a second cycle. Eradication was associated with a significant decrease in neutrophil elastase and interleukin-1β in BAL fluid 12 months post eradication. Eradication of Pseudomonas aeruginosa infection is achievable in young children with cystic fibrosis for up to 5 yrs using combination i.v., oral and nebulised antibiotic therapy and is associated with reduced pulmonary inflammation 12 months post eradication.

Inflammatory responses to individual microorganisms in the lungs of children with cystic fibrosis.

BACKGROUND We hypothesized that the inflammatory response in the lungs of children with cystic fibrosis (CF) would vary with the type of infecting organism, being greatest with Pseudomonas aeruginosa and Staphylococcus aureus. METHODS A microbiological surveillance program based on annual bronchoalveolar lavage (BAL) collected fluid for culture and assessment of inflammation was conducted. Primary analyses compared inflammation in samples that grew a single organism with uninfected samples in cross-sectional and longitudinal analyses. RESULTS Results were available for 653 samples from 215 children with CF aged 24 days to 7 years. A single agent was associated with pulmonary infection (≥10(5) cfu/mL) in 67 BAL samples, with P. aeruginosa (n = 25), S. aureus (n = 17), and Aspergillus species (n = 19) being the most common. These microorganisms were associated with increased levels of inflammation, with P. aeruginosa being the most proinflammatory. Mixed oral flora (MOF) alone was isolated from 165 BAL samples from 112 patients, with 97 of these samples having a bacterial density ≥10(5) cfu/mL, and was associated with increased pulmonary inflammation (P < .001). For patients with current, but not past, infections there was an association with a greater inflammatory response, compared with those who were never infected (P < .05). However, previous infection with S. aureus was associated with a greater inflammatory response in subsequent BAL. CONCLUSIONS Pulmonary infection with P. aeruginosa, S. aureus, or Aspergillus species and growth of MOF was associated with significant inflammatory responses in young children with CF. Our data support the use of specific surveillance and eradication programs for these organisms. The inflammatory response to MOF requires additional investigation.

Evolution of pulmonary inflammation and nutritional status in infants and young children with cystic fibrosis

Introduction Improved nutrition is the major proven benefit of newborn screening programmes for cystic fibrosis (CF) and is associated with better clinical outcomes. It was hypothesised that early pulmonary inflammation and infection in infants with CF is associated with worse nutrition. Methods Weight, height and pulmonary inflammation and infection in bronchoalveolar lavage (BAL) were assessed shortly after diagnosis in infants with CF and again at 1, 2 and 3 years of age. Body mass index (BMI) was expressed as z-scores. Inflammatory cells and cytokines (interleukin 1β (IL-1β), IL-6, IL-8 and tumour necrosis factor α (TNFα)), free neutrophil elastase activity and myeloperoxidase were measured in BAL. Mixed effects modelling was used to assess longitudinal associations between pulmonary inflammation, pulmonary infection (Staphylococcus aureus and Pseudomonas aeruginosa) and BMI z-score after adjusting for potential confounding factors. Results Forty-two infants were studied (16 (38%) male; 39 (93%) pancreatic insufficient); 36 were diagnosed by newborn screening (at median age 4 weeks) and six by early clinical diagnosis (meconium ileus). Thirty-one (74%) received antistaphylococcal antibiotics. More than two-thirds were asymptomatic at each assessment. Mean BMI z-scores were −1.5 at diagnosis and 0.5, −0.2 and −0.1 at 1, 2 and 3 years, respectively. Neutrophil elastase and infection with S aureus were associated with lower BMI, whereas age (p=0.01) and antistaphylococcal antibiotics (p=0.013) were associated with increased BMI. On average, each log10 increase in free neutrophil elastase activity was associated with a 0.43 (95% CI 0.06 to 0.79) reduction in BMI z-score. Discussion Early nutritional status is associated with the underlying pulmonary pathophysiology in CF, and better understanding of these relationships is required. Studies are required to assess whether interventions can decrease pulmonary inflammation and improve nutrition. Early surveillance will enable such targeted interventions with the aim of improving these important clinical outcomes.

Assessment of bronchodilator responsiveness in preschool children using forced oscillations

Background: The forced oscillation technique (FOT) requires minimal patient cooperation and is feasible in preschool children. Few data exist on respiratory function changes measured using FOT following inhaled bronchodilators (BD) in healthy young children, limiting the clinical applications of BD testing in this age group. A study was undertaken to determine the most appropriate method of quantifying BD responses using FOT in healthy young children and those with common respiratory conditions including cystic fibrosis, neonatal chronic lung disease and asthma and/or current wheeze. Methods: A pseudorandom FOT signal (4–48 Hz) was used to examine respiratory resistance and reactance at 6, 8 and 10 Hz; 3–5 acceptable measurements were made before and 15 min after the administration of salbutamol. The post-BD response was expressed in absolute and relative (percentage of baseline) terms. Results: Significant BD responses were seen in all groups. Absolute changes in BD responses were related to baseline lung function within each group. Relative changes in BD responses were less dependent on baseline lung function and were independent of height in healthy children. Those with neonatal chronic lung disease showed a strong baseline dependence in their responses. The BD response in children with cystic fibrosis, asthma or wheeze (based on both group mean data and number of responders) was not greater than in healthy children. Conclusions: The BD response assessed by the FOT in preschool children should be expressed as a relative change to account for the effect of baseline lung function. The limits for a positive BD response of −40% and 65% for respiratory resistance and reactance, respectively, are recommended.

Identifying peroxidases and their oxidants in the early pathology of cystic fibrosis

We aimed to determine whether myeloperoxidase (MPO) is the main peroxidase present in the airways of children with cystic fibrosis (CF) and to assess which oxidants it produces and whether they are associated with clinical features of CF. Children with CF (n=54) and without CF (n=16) underwent bronchoscopy and bronchoalveolar lavage (BAL) for assessment of pulmonary infection and inflammation. BAL fluid was analyzed for MPO, halogenated tyrosines as markers of hypohalous acids, thiocyanate, and protein carbonyls. MPO was the only peroxidase detected in BAL samples from children with CF and its concentration was markedly higher than in controls. Levels of 3-chlorotyrosine and 3-bromotyrosine in proteins were higher in the CF group. They correlated with neutrophils and MPO. The concentration of thiocyanate in BAL samples was below 1μM. Protein carbonyl levels correlated with MPO and halogenated tyrosines in patients with CF. Levels of MPO and halogenated tyrosines were higher in children with infections, especially Pseudomonas aeruginosa, and in the presence of respiratory symptoms. They also correlated with the Kanga clinical score. Our findings suggest that MPO produces hypobromous acid as well as hypochlorous acid in the airways of children with CF and that these oxidants are involved in the early pathogenesis of CF.

RESPIRATORY FUNCTION IN HEALTHY YOUNG CHILDREN USING FORCED OSCILLATIONS

Background: Monitoring of respiratory function is important in the diagnosis and management of respiratory disease. The forced oscillation technique requires minimal patient cooperation and is ideal for the determination of respiratory function in young children. This study aimed to develop reference ranges and to document the repeatability in healthy young children using commercially available forced oscillation equipment. Methods: The forced oscillation technique, which uses a pseudo-random noise forcing signal between 4 and 48 Hz, was used to measure respiratory function in healthy young children. Repeatability over a 15 min period was also assessed. Regression equations and standardised Z scores were determined for respiratory resistance (Rrs) and reactance (Xrs) at 6, 8 and 10 Hz. Results: Respiratory function was obtained in 158 healthy children aged two to seven years and between 92 and 127 cm in height. Oscillatory respiratory mechanics exhibited linear relationships with height. Within-test variability for resistance ranged between 6% and 9% and between 17% and 20% for reactance. Resistance and reactance did not change significantly over a 15 min period. Conclusions: Reference ranges for respiratory impedance variables in healthy children aged two to seven years are presented. The short-term repeatability of forced oscillatory variables in this age group is reported, allowing appropriate cut-off values for therapeutic interventions to be defined.

Respiratory impedance in children with cystic fibrosis using forced oscillations in clinic

Measurement of lung function is an important component of clinical management in cystic fibrosis (CF), but has been difficult in young children. The present study aimed to characterise the utility of the forced oscillation technique for measurement of lung function in preschool-aged children with CF in a routine clinical setting. Lung function was assessed in 56 young children (aged 2–7 yrs) with CF. Respiratory system resistance (Rrs) and reactance (Xrs) at 6, 8 and 10 Hz were measured and expressed as Z-scores. Children were classified as asymptomatic or symptomatic based on an administered respiratory questionnaire and physical examination at the time of testing. Between-test repeatability was assessed in 25 children. Measurement of lung function using the forced oscillation technique was feasible in the CF clinic. The children with CF, as a group, had Z-scores for Rrs at 6 Hz (Rrs,6) Rrs,8, Rrs,10, Xrs at 6 Hz (Xrs,6) and Xrs,8 that were significantly different from zero. Children with current symptoms showed significantly decreased Xrs and increased Rrs,6 compared with asymptomatic children. Measurement of lung function using the forced oscillation technique is feasible in young children with cystic fibrosis in a clinical setting. The technique has the potential to improve knowledge concerning early cystic fibrosis lung disease.