An IL-6 high phenotype in children with asthma is associated with obesity and neutrophilia.

BACKGROUND: IL-6 is a proinflammatory cytokine that has been shown to mediate inflammation in several chronic diseases, including diabetes mellitus and cardiovascular disease. It has emerged in the past decade as a potential biomarker for asthma in adults, but an IL-6 high phenotype in children has yet to be defined. OBJECTIVE: We aimed to determine if an IL-6 high phenotype could be identified in children with asthma, and its relation to other clinical and biologic characteristics previously identified as significant in individuals with asthma. METHODS: We conducted a single-center, prospective, observational study to quantify plasma IL-6 levels in children ages 6-17 years from an urban outpatient clinic. Both children with asthma and controls without asthma were recruited. Blood samples, lung function testing, and questionnaires were collected at a single study visit. RESULTS: An IL-6 high phenotype was identified in this diverse pediatric population that was not seen in healthy controls. High plasma IL-6 levels were associated with obesity, high CRP, and neutrophilia but not age, asthma severity, plasma IL-6R levels or plasma fatty acid levels. High IL-6 levels were not distinct from type-2 associated inflammation; rather, the two demonstrated significant overlap. CONCLUSION: In our single center study, an IL-6 high phenotype was identified in children with asthma that was associated with obesity and neutrophilia but not independent from atopic disease. Further work is needed to determine if IL-6 modulation can impact asthma morbidity in children.