Effect of Anti-IL5 and Anti-IgE on Alternative Functions of Eosinophils in Severe Asthma

Severe asthma is observed in 3 to 5% of the asthmatic population and is characterized by a higher rate of exacerbations, poorly controlled asthma and/or a poor lung function. During the last ten years, anti- Immunoglobulin E (IgE) and anti-IL5 (and anti-IL5R) have considerably improved severe asthma status. Treatment with chronic or oral course of corticosteroids is indeed responsible for a lot of side effects. There is however a lack of biomarkers for the prediction of responders to anti-IL5 and anti-IgE.

The investigators have previously found that sputum eosinophil counts are good predictors for improvement in lung function of severe asthmatics using anti-IL5. Sputum cells might not be the only relevant sputum marker for responders to biologics.

The objective is to evaluate the ability of sputum cytokines (protein levels and genes) (IL-3, IL-4, IL-5, IL-13, IL-33 and GM-CSF) to predict the response of severe asthmatics after 6 months and 1 year of treatment with biologics in terms of reduction in exacerbations and corticosteroid use, improvement in FEV1, in asthma control, in asthma quality of life and the effect on sputum and blood inflammation.

Severe asthmatics seen in the Asthma Clinic of CHU of Liege are very well characterized using baseline measure of blood samples, induced sputum, lung function, fractional exhaled nitric oxide (FeNO), asthma control questionnaires (ACT - ACQ) and asthma quality of life questionnaires (AQLQ).

Data on exacerbations during the previous year and current inhaled and oral treatment is also recorded. If FEV1 value is upper than 70% of the predicted value, severe asthmatics also perform a methacholine challenge to evaluate bronchial hyperresponsiveness.