Severe Eosinophilic Asthma or Eosinophilic Granulomatosis With Polyangiitis: Potential Biomarkers for Novel Diagnostic Strategies

Abstract

BackgroundSevere Eosinophilic Asthma (SEA) may be the prodromal phase of Eosinophilic Granulomatosis with Polyangiitis (EGPA). Nevertheless, few studies have tried to recognize EGPA in the early stages of the disease. ObjectivesTo identify a panel of clinical and biological markers to detect which severe asthmatic patient might be considered in a prodromal phase of EGPA and crafting a strategy for diagnostic decision-making. Methods30 patients with EGPA and 49 with SEA were enrolled. A complete pulmonary, ear, nose and Throat (ENT) and rheumatologic assessment were made. Blood (eosinophil count, eosinophilic cationic protein-ECP, IL5, IL4, total-IgE, IgG4, anti-neutrophil cytoplasmic antibody (ANCA), sputum (eosinophils count, periostin, IL8 and GMCSF) and nasal smear (eosinophilia) biomarkers were assessed. Asthma Control Test, Short Form-36, SinoNasalOutcome Test-22, and Asthma Quality of Life Questionnaire were also used. ResultsSEA patients had poorer asthma control (p<0.001) and higher level of sputum eosinophils (p<0.002) while EGPA patients reported higher levels of blood eosinophils in the past. Sputum GMCSF was the only biomarker significantly increased in EGPA patients compared with SEA (p<0.0001). Among SEA patients, those with some suggestive but not diagnostic criteria of EGPA, particularly tissue eosinophilic infiltrates, presented higher levels of sputum GMCSF (p<0.0005), blood and sputum eosinophils (p<0.0006, p<0.011) in comparison with the other patients. ConclusionSputum GMCSF and eosinophils might be useful biomarkers to support early diagnosis and treatment choices in SEA patients, suspected of having EGPA