Severe asthma is an epithelial disease

Abstract

Asthma is an important, clinically prevalent disease worldwide. Despite a better knowledge on the pathogenesis, the mechanisms underlying the induction and persistence of the disease are largely unknown. It is now accepted that airway inflammation and structural changes of the bronchi are important features. The relationships between those structural changes and clinical and functional abnormalities clearly deserved further investigations. These findings led to the reinforcement of the use of inhaled corticosteroids as the pivotal treatment for asthma. Nevertheless, there are still patients who have persistent symptoms, altered lung function and a high rate of exacerbations, despite long-term specialist follow-up and continuous optimal treatment. These severe patients have a major handicap in their daily life and are responsible for most of the costs created by asthma 1. Therefore, it is of major importance to better understand the mechanisms leading to this severe phenotype. Almost one century ago, Ellis 2 highlighted that the pathology of asthma could be investigated by examining sputum from living patients or the lungs of patients who die during an attack. From these sources, the role of bronchial epithelium was clarified by describing elongated epithelial cells in the sputum and the presence of abnormalities of the pseudo-stratified and ciliated epithelium in most fatal cases, albeit it varied considerably as regards location and extent 2. The role played by …