An interleukin (IL)-6 high phenotype in children with asthma is associated with obesity and neutrophilia

Interleukin (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.

To determine whether 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.

We conducted a single-center, prospective, observational study to quantify plasma IL-6 levels in children aged 6 to 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.

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 C-reactive protein, and neutrophilia but not with age, asthma severity, plasma IL-6 receptor levels, or plasma fatty acid levels. High IL-6 levels were not distinct from type 2-associated inflammation; rather, the 2 revealed significant overlap.

In our single-center study, an IL-6-high phenotype was identified in children with asthma that was associated with obesity and neutrophilia but was not independent of atopic disease. Further work is needed to determine whether IL-6 modulation can impact asthma morbidity in children.