Immunological and epithelial barrier dysfunction in EGPA: the possible role of new biomarkers

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare systemic vasculitis with heterogeneous clinical manifestations. Identifying reliable biomarkers is crucial to predicting disease evolution and guiding therapy. We analyzed clinical, biological, and functional data from 33 patients with EGPA in the vasculitic phase. Blood eosinophil count (BEC), eosinophilic cationic protein (ECP), antineutrophil cytoplasmic antibodies (ANCAs), specific IgE to staphylococcal enterotoxins (SE-IgE), and serum free light chains (FLCs) were evaluated. Severe eosinophilic asthma (SEA) and chronic rhinosinusitis with nasal polyps (CRSwNPs) were present in 100% and 88.5% of patients, respectively. Median BEC was 1950 cells/mm3, with elevated ECP (60.0 µg/L). SE-IgE was detected in 54.2% of patients. A significant negative correlation emerged between λ FLCs and oral corticosteroid (OCS) dose (r = –0.58, p = 0.009). Forced expiratory volume in 1 second (FEV1) was significantly lower in C-ANCA+ patients (p = 0.006). ECP and SE-IgE may serve as markers of eosinophilic activity and epithelial barrier damage in EGPA. λ FLCs might be a useful indicator of OCS exposure and treatment response. These biomarkers could support the evaluation of disease evolution and treatment response.