Inflammatory phenotypes in stable and acute childhood asthma

Asthma is a complex disease with a significant inflammatory component characterized by repeated episodes of exacerbation and inflammatory changes in both large and peripheral airways. The clinical course of childhood asthma varies substantially among individuals. The reasons why the clinical course of asthma displays persistence and even progression in some children but is intermittent in others remains unclear. Children with asthma are different from adults with asthma. Inflammatory involvement in children with asthma appears to be localised more in peripheral than central airways, and the inflammatory phenotype displays differences from adults. Children with acute asthma display a dominant eosinophilic inflammatory phenotype instead of the neutrophilic phenotype that is seen in adults with acute asthma. Corticosteroids do not alter the natural history of the disease and may not prevent progressive decline of lung function in the subset of severe asthma. The underlying inflammatory mechanisms involved in the decline of lung function remains to be elucidated. Non-invasive biomarkers for monitoring lung function and inflammation are needed in children to track and monitor pathological changes in the distal airways, as is the development of therapeutic strategies that effective to peripheral airway in this vulnerable population. This review summarises our present understanding of airway inflammatory phenotypes in children with asthma and factors determining disease severity in exacerbations of asthma, and focuses on studies evaluating relationships between clinical features and the dominant inflammatory phenotypes in disease prognosis in a variety of asthma populations. This presents the crucial steps for describing the strategies associated with improvements for paediatric asthma care.