T2-Low Asthma: Overview and Management Strategies

Although the term asthma has been applied to all patients with airway lability and variable chest symptoms for centuries, phenotypes of asthma with distinct clinical and molecular features that may warrant different treatment approaches are well recognized. Patients with type 2 (T2)-high asthma are characterized by upregulation of T2 immune pathways (ie, IL-4 and IL-13 gene sets) and eosinophilic airway inflammation, whereas these features are absent in patients with T2-low asthma and may contribute to poor responsiveness to corticosteroid treatment. This review details definitions and clinical features of T2-low asthma, potential mechanisms and metabolic aspects, pediatric considerations, and potential treatment approaches. Priority research questions for T2-low asthma are also discussed. (C) 2019 American Academy of Allergy, Asthma & Immunology