Neutrophilic asthma: a complex phenotype of severe asthma

Asthma is a common chronic airway disease affecting about 334 million people worldwide, and an estimated 7 million children globally. Approximately 10% of patients with asthma have severe refractory disease, which is difficult to control on high doses of inhaled corticosteroids and other modifiers. Among these, are patients with severe neutrophilic asthma. Neutrophilic asthma is a phenotype of asthma that is very severe and persistent, with frequent exacerbations, and characterized by fixed airway obstruction. It is associated with comorbidities such as respiratory infections, obesity, gastroeosophageal reflux disease, and obstructive sleep apnoea. Immunopathologically, it is characterized by the presence of high levels of neutrophils in the lungs and airways. Neutrophils and the interleukin-17 family of cytokines play a pivotal role in the pathogenesis of severe neutrophilic asthma. Most patients with the disease do not achieve control with high dose inhaled corticosteroids, and probably to novel IgE, interleukin and interleukin monoclonal antibodies.