Blocking a certain immune molecule produced in the lungs reduces obesity associated with asthma in mice, reports a study published this week in Nature Medicine.

Obesity is a risk factor for asthma, and elevated body mass index is associated with a higher risk of developing asthma. Although weight loss decreases asthma symptoms, obese individuals respond poorly to currently approved asthma medications and the underlying causes for this form of asthma remain unclear.

Dale Umetsu and his colleagues report that mice fed a high-fat diet develop airway hyperreactivity, a cardinal symptom of asthma. In these mice, the high-fat diet induces a subset of immune cells termed macrophages to produce the immune system molecule interleukin-1b (IL-1b), which then promotes the secretion of another molecule, IL-17, which can worsen airway disease. Administration of a clinically-approved drug that blocks the binding of IL-1b to its receptor prevents IL-17 release and reduces airway disease in obese mice. As the cell type producing IL-17 are found in the airways of individuals with asthma, these findings suggest that this form of asthma may be treated by targeting the IL-1b pathway.