T2-high asthma phenotypes across lifespan

Rationale In adults, personalised asthma treatment targets patients with T2-high and eosinophilic asthma phenotypes. It is unclear whether such classification is achievable in children. Objectives To define T2-high asthma with easily accessible biomarkers and compare resulting phenotypes across all ages. Methods In the multicenter clinical ALL Age Asthma Cohort (ALLIANCE), 1125 participants (n=776 asthmatics, n=349 controls) were recruited and followed for 2 years (1 year in adults). Extensive clinical characterisation (questionnaires, blood differential count, allergy testing, lung function and sputum induction (in adults) was performed at baseline and follow-ups. Interleukin (IL)-4, IL-5 and IL-13 were measured after stimulation of whole blood with LPS or anti-CD3/CD28. Measurements and Main Results Based on blood eosinophil counts and allergen-specific serum IgE antibodies (sIgE), patients were categorised into four mutually exclusive phenotypes: “Atopy-only”, “Eosinophils-only”, “T2-high” (eosinophilia+atopy) and “T2-low” (neither eosinophilia nor atopy). The T2-high phenotype was found across all ages, even in very young children in whom it persisted to a large degree even after 2 years of follow-up. T2-high asthma in adults was associated with childhood onset suggesting early origins of this asthma phenotype. In both children and adults, the T2-high phenotype was characterised by excessive production of specific IgE to allergens (p