• Eosinophilic granulomatosis with polyangiitis
• Inflammatory pathways
• therapy.

Our study described a cohort of EGPA patients eligible to mepolizumab. Reasons to introduce mepolizumab were active vasculitis and/or poor control of asthma and CRS. We confirmed the safety and the efficacy of mepolizumab after 6 and 12 months of follow-up from a clinical and biohumoral point of view. A subgroup analysis showed that NETs and EETs profile at baseline is correlated to atopy and could be influenced by ANCA status. After mepolizumab introduction NETosis and EETosis are both reduced and the pattern of response depends on ANCA and atopy profile of patients. These data suggest that the cross-talk between neutrophils and eosinophils appear a cornerstone in EGPA pathogenesis. Further studies will better characterize the NETosis and EETosis profile in larger samples of patients and analyse the potential role of NETs and EETs as biomarkers of specific disease phenotypes and response to treatments targeting type 2 inflammation.