Release of Airway Alarmins IL ‐33 and TSLP in Paediatric Acute Severe Asthma: A Case–Control Study

Aim Interleukin (IL)‐33 and thymic stromal lymphopoietin (TSLP) released in the airways are believed to be associated with a greater risk of childhood‐onset asthma. The aim of this study was to measure the release of IL‐33 and TSLP into the airways of children and young people (CYP) during asthma attacks and compare these alarmin‐cytokine levels with stable disease patients and non‐asthmatic controls. Methods We conducted a prospective observational case–control feasibility study, where we measured the levels of IL‐33 and TSLP using high sensitivity immunoassays in the airways of children and young people (CYP) during asthma attacks, stable disease patients and non‐asthmatic control individuals. Results Median concentrations of sputum IL‐33 and TSLP from acute asthmatics were 3.4 and 17.7 times higher, respectively, in acute asthmatics compared to stable asthmatic children. Sputum IL‐33 and TSLP were not different in the stable asthma group compared to non‐asthmatic controls. Conclusion IL‐33 and TSLP were significantly elevated during acute severe asthma attacks and could potentially drive further airway inflammation and remodelling during asthma attacks in children. Results support further clinical evaluation of anti‐TSLP and anti‐IL‐33 biologic therapeutics for preventing or reducing the frequency of asthma attacks in children.