Asthma and small airways

Abstract

Asthma is a chronic inflammatory disease of the airway characterized by episodic airway obstruction and increased bronchial responsiveness. The concept that inflammation is a major component of asthmatic pathology was establishe more than 100 years ago, but the attention had been focussed on the large asthmatic airways. That the distal airways and the lung parenchyma play a role in asthma has been suggested later. The distal airways have now been recognized as a predominant site of airflow obstruction in asthmatics. It is now accepted that in asthmatics, recruitment of inflammatory cells, in particular eosinophils and T cells, also occurs in the distal lung and the lung parenchyma.[In addition, in asthmatics there is an abundance of Th2-type cytokines and chemokines present at this distal site. The current therapeutic challenge is to develop better inhalation technologies to improve the delivery of anti-inflammatory agents to the lung periphery. This article aims to evaluate the pathological and physiological evidence presented in the literature to date, which outlines the contribution of the distal lung and the lung parenchyma to the pathophysiology of asthma.