Asthma is associated with increased susceptibility to infection

Asthma is a chronic inflammatory disorder of the airways characterized by airway hyperresponsiveness and airflow limitation. Despite respiratory symptoms may be episodic, progressive changes occur in the structure of the airway, leading to its irreversible remodeling. Changes include mucus hypersecretion, injury to epithelial cells, smooth muscle hypertrophy, sub-basement membrane fibrosis and angiogenesis. The risk factors for developing asthma are a combination of genetic predisposition along with environmental exposure to inhaled substances and particles that may provoke allergic reactions or irritate the airways, such as in- and out-door allergens, tobacco smoke, chemical irritants in the workplace and air pollution. Asthma is a clinically heterogeneous entity due to the complexity of its pathogenetic substrate. Recent evidence suggests asthma to be associated with a sort of immunodeficiency accounting for an increased susceptibility to infection in asthmatic patients. The role of infections as triggers and promoters of disease progression is well established. Conversely, the impact of asthma as a predisposing condition to infection has not clearly been addressed. Such a topic will be the focus of the present review.