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Persistence of sputum eosinophilia in children with controlled asthma when compared with healthy children
1Airway Research Centre, Respiratory Medicine Unit, John Hunter Hospital, New South Wales, Australia.
Insights
Induced sputum analysis reveals higher eosinophils and epithelial cells in children with asthma, even when controlled. This indicates persistent airway inflammation and damage in pediatric asthma patients.
Area of Science:
- Pediatric Pulmonology
- Respiratory Medicine
- Cellular Biology
Background:
- Asthma is a common chronic respiratory disease in children.
- Assessing airway inflammation in pediatric asthma is crucial for effective management.
- Current treatments aim to control symptoms and lung function, but inflammation may persist.
Purpose of the Study:
- To quantify induced sputum cell counts in healthy children.
- To compare sputum cell profiles between healthy children and those with controlled and uncontrolled asthma.
- To investigate airway inflammation and epithelial damage in pediatric asthma.
Main Methods:
- Induced sputum was collected from children with asthma (n=50) and healthy controls (n=72) using nebulized hypertonic saline.
- Sputum cell counts (total and differential) were performed, with specific stains for eosinophils and mast cells.
- Asthma control was assessed via symptoms and lung function; children were classified as controlled, symptomatic, or in exacerbation.
Main Results:
- Children with asthma showed significantly higher sputum eosinophils (4.3%) and epithelial cells (14%) compared to healthy children (0.3% eosinophils).
- Elevated eosinophils and epithelial cells were observed in both controlled and symptomatic pediatric asthma groups.
- Mast cells were infrequently detected in the sputum of children with asthma.
Conclusions:
- Eosinophilic airway inflammation and epithelial damage are present in children with asthma.
- Airway inflammation persists in pediatric asthma patients despite treatment with inhaled corticosteroids, normal lung function, and good symptomatic control.
- Induced sputum analysis can identify ongoing airway inflammation in pediatric asthma.
Abstract:
We aimed to describe induced sputum cell counts in healthy nonasthmatic children, and to compare these to children with controlled and uncontrolled asthma. Following clinical assessment and spirometry, ultrasonically nebulized hypertonic saline was used to induce sputum from children with asthma (n=50) and without asthma (n=72). Sputum was dispersed and cell counts performed to yield total and differential cell counts. Specific stains were used for eosinophil and mast cell counts. All of the children with asthma were receiving inhaled and/or oral corticosteroids. Current asthma control was assessed in terms of symptoms and lung function. Children were classified as controlled on inhaled corticosteroids (no current symptoms, normal lung function n=15), current symptomatic asthma (n=16) and asthma exacerbation (n=11). It was found that eosinophils comprised a median 0.3% (interquartile range (IQR): 0, 1.05) of cells in sputum from healthy children. Sputum eosinophils (4.3% (IQR: 15, 14.1) p=0.0005) and epithelial cells (14% (IQR: 6, 19.4) p=0.0005) were significantly higher in children with asthma than in nonasthmatic children. Children whose asthma was controlled, as well as those with symptoms, had more sputum eosinophils and epithelial cells than the nonasthmatics. Mast cells were found in the sputum of only four of the 42 children with asthma. This study demonstrates that eosinophilic airway inflammation and epithelial damage can occur in children with asthma. Airway inflammation persists even in those children who are receiving inhaled corticosteroids, have normal lung function and good symptomatic control of their disease.