Sputum Eosinophil and Macrophage Changes After Aspirin Challenge in Patients With Nonsteroidal Anti-Inflammatory...

Induced sputum cell count is crucial for assessing airway inflammatory phenotypes. This study investigated how aspirin-induced bronchospasm affects sputum cell counts in patients with nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (N-ERD), comparing systemic versus local aspirin administration.

Seventy-eight patients with N-ERD and 39 with aspirin-tolerant asthma (ATA) participated. In the N-ERD group, induced sputum was collected before aspirin challenge and during aspirin-induced bronchospasm. We assessed changes in the percentages of eosinophils, neutrophils, lymphocytes, and macrophages, and airway inflammatory phenotypes classified by sputum cells into: (A) eosinophilic, neutrophilic, paucigranulocytic, and mixed; and (B) eosinophilic and noneosinophilic.

Baseline sputum neutrophil percentage was lower in the N-ERD than in the ATA (32.9% ± 20.8% vs. 41.6% ± 22.5%; p = 0.02). Inflammatory phenotypes at baseline differed between groups in both classifications (A: p = 0.041; B: p = 0.044). In the N-ERD group, sputum eosinophil percentage decreased after both oral (8.9% ± 11.6% vs. 6.1% ± 8.9%, p = 0.009) and inhaled (10.4% ± 16.1% vs. 4.8% ± 6.3%, p = 0.045) challenges, without altering inflammatory phenotypes. The ATA group showed no changes. Sputum macrophage percentage dropped after oral challenge in both groups (N-ERD: 40.5% ± 18.5% vs. 35.6% ± 21.5%; p = 0.004; ATA: 36.5% ± 23.6% vs. 26.7% ± 20.4%; p = 0.0003). In the N-ERD group, baseline sputum lymphocyte and eosinophil percentages were inversely correlated with the provocative dose of aspirin that resulted in a 20% decrease in baseline forced expiratory volume in 1 s following oral aspirin challenge (R = -0.31, p = 0.02 and R = -0.33, p = 0.02, respectively).

In N-ERD, sputum eosinophil percentage decreased after aspirin challenge regardless of administration route. In both N-ERD and ATA, sputum macrophage percentage decreased after oral aspirin challenge.