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

Background: Severe 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.

Objective: To 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.

Methods: A total of 30 patients with EGPA and 49 with SEA were enrolled. A complete pulmonary, ear, nose, and throat, and rheumatologic assessment were made. Blood (eosinophil count, eosinophilic cationic protein, IL-5, IL-4, total-IgE, IgG₄, and antineutrophil cytoplasmic antibody), sputum (eosinophils count, periostin, IL-8, and granulocyte-monocyte colony-stimulating factor [GM-CSF]), 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.

Results: Patients with SEA had poorer asthma control (P < .001) and a higher level of sputum eosinophils (P < .002), whereas patients with EGPA reported higher levels of blood eosinophils in the past. Sputum GM-CSF was the only biomarker significantly increased in patients with EGPA compared with those with SEA (P < .0001). Among patients with SEA, those with some suggestive but not diagnostic criteria of EGPA, particularly tissue eosinophilic infiltrates, presented higher levels of sputum GM-CSF (P < .0005), blood, and sputum eosinophils (P < .0006 and P < .011) than the other patients.

Conclusion: Sputum GM-CSF and eosinophils might be useful biomarkers to support early diagnosis and treatment choices in patients with SEA, suspected of having EGPA.