The effect of anti-IL-5 therapy on sputum cells and cytokines in asthmatics

<b>Introduction:</b> 'Mepolizumab', an anti-interleukin-5 (IL-5) monoclonal antibody therapeutic, is recommend as targeted therapy for severe eosinophilic asthmatics. Clinical trials showed reduced exacerbation rates and improved quality of life after anti-IL-5 therapy. However, the effect of anti-IL-5 therapy on immunological parameters and their predictive value for treatment response has only sparsely been investigated in asthmatics. <b>Methods:</b> Twenty-two asthmatics who were eligible for anti-IL-5 therapy were recruited. Patients received a monthly subcutaneous injection with 100mg 'mepolizumab' for 6 months. Lung function and FeNO measurement, sputum induction to determine airway inflammation and cytokine patterns, an asthma control test and blood sampling were performed at initiation and after 6 months treatment. <b>Results:</b> Our study showed a significant improvement of FEV1(% pred), FVC(%), asthma control and number of exacerbations after 6 months of treatment. Besides, eosinophilic airway inflammation was significantly lower after anti-IL-5 therapy, which was not the case for FeNO, a biomarker for airway eosinophilia. Additionally, 'mepolizumab' treatment resulted in significant decreased levels of sputum IL-5, IL-4, IL-13, IL-17A and IFN-γ. However, sputum cytokine levels at initiation were not able to predict treatment response. <b>Conclusion:</b> We were able to confirm the findings of previous clinical trials by showing improved lung function, asthma control, number of exacerbations and airway inflammation after 6 months anti-IL-5 therapy. Besides, we also showed decreased sputum cytokine levels after therapy for a range of cytokines (IL-5, IL-4, IL-13, IL-17A and IFN-γ), suggestive for a broader anti-inflammatory effect.