Related Experiment Video
Updated: Nov 13, 2025
Methodology for Sputum Induction and Laboratory Processing
Published on: December 17, 2017
Stability of sputum inflammatory phenotypes in childhood asthma during stable and exacerbation phases
Yuk Ping Tsang1,2, Julie M Marchant1,3, Albert M Li4
1Centre for Healthcare Transformation, Queensland University of Technology, Brisbane, Queensland, Australia.
Insights
Sputum inflammatory phenotypes in children with asthma are unstable during both stable and exacerbation periods, unlike in adults. This variability impacts asthma management strategies for pediatric patients.
Area of Science:
- Pediatric Pulmonology
- Asthma Research
- Inflammatory Diseases
Background:
- Asthma management increasingly utilizes airway inflammation phenotypes.
- Sputum phenotypes are stable in adult asthma but data in children is limited.
- Childhood asthma requires understanding phenotype stability for effective treatment.
Purpose of the Study:
- To assess the stability of sputum inflammatory phenotypes in children with asthma.
- To compare phenotype stability during stable and exacerbation phases.
- To provide data on pediatric asthma phenotype variability.
Main Methods:
- Re-evaluated sputum cellularity from two prospective childhood asthma studies.
- Classified phenotypes as eosinophilic (>2.5% eosinophils) or noneosinophilic (≤2.5% eosinophils).
- Compared baseline and follow-up phenotype classifications during stable and exacerbation phases.
Main Results:
- 41% of children with stable asthma showed phenotype changes after 8 weeks.
- During exacerbations, phenotype categorization changed in 22% on Day 1 and 13% on Day 3.
- Sputum eosinophil and neutrophil percentages increased during exacerbations.
Conclusions:
- Sputum inflammatory phenotypes in pediatric asthma are variable.
- Phenotype instability exists in both stable and exacerbation phases.
- Findings contrast with the stability observed in adult asthma patients.
Background:
Management strategies based on airway inflammation phenotypes are increasingly used for adults with asthma. While sputum-based phenotypes are relatively stable in adults with asthma, there is little such data in childhood asthma. Hence, we aimed to evaluate the stability of sputum inflammatory phenotypes in children with asthma both in the stable and during exacerbation phases.
Methods:
Sputum cellularity data from two previous prospective studies involving children with asthma were re-evaluated and categorized into two inflammatory phenotypes: eosinophilic (>2.5% eosinophils) and noneosinophilic (≤2.5% eosinophils). Baseline values and follow-up sputum inflammatory phenotype classification were compared in children with asthma during stable and exacerbation phases.
Results:
Thirteen of 32 children (41%) with stable asthma demonstrated a change in sputum inflammatory phenotype 8 weeks later. In a different second cohort, both sputum eosinophils and neutrophils percentages increased and peaked on Day 1 of asthma exacerbation, but compared with baseline, 22% (2/9) and 13% (1/8) of these children had their sputum phenotype categorization changed on Day 1 and Day 3 of exacerbation, respectively.
Conclusion:
In children with asthma, sputum inflammatory phenotypes are variable in both stable and exacerbation phases, in contrast to data in adults.
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