Published online: February 22, 2018
Asthma is a variable disease characterized by periods of instability that can result in exacerbations. Many studies have described different phenotypes of asthma during a period of stability, highlighting the heterogeneity of stable asthma. None have examined phenotypes during an exacerbation when changes in lung function and inflammation would be at their worst.
In a recently published article in The Journal of Allergy and Clinical Immunology: In Practice, Dr. Qiu and colleagues put forward the hypothesis that the clusters obtained by studying patients recovering from an acute exacerbation of asthma would be different from those already described in adult patients with asthma during a stable period, because the degree of inflammation and lung function deterioration would be more prominent. In this study, these investigators from Guangzhou, China, collected clinical, inflammatory, and biomarker data during recovery from an exacerbation in patients with asthma treated in a university hospital.
Using an unsupervised cluster analysis, four clusters were defined by varying degrees of airflow obstruction and granulocytic inflammation measured in sputum samples. Clusters 1 and 3 were characterized by predominantly-female asthmatics with sputum neutrophilia, Cluster 1 manifested a small degree of airflow obstruction and early onset of asthma, while Cluster 3 had a moderate degree of airflow obstruction. Clusters 2 and 4 were associated with high sputum eosinophilia and severe airflow obstruction, with Cluster 2 consisting of female non-smoking subjects with the most severe airflow obstruction a nd Cluster 4 made up entirely of male smoking subjects.
Eosinophilic or neutrophilic inflammation in association with different degrees of airflow obstruction formed the basis of the 4 clusters described during recovery from an exacerbation. Eosinophilic inflammation associated with severe airflow obstruction was seen in both male smoking and female non-smoking asthmatic subjects. Delineation of these clusters of asthma during recovery from an exacerbation may help in targeting specific treatments for these different exacerbation phenotypes.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.