Introduction:

Eosinophilic airway inflammation is common in severe asthma, yet its biological features may vary depending on age of onset. This study sought to characterize eosinophilic inflammation in patients with childhood-onset (age <18) and adult-onset (age ≥18) asthma.

Methods:

• Data from adult patients (≥18 years) enrolled in the U-BIOPRED study were analyzed.
• Definition of eosinophilic inflammation: Sputum eosinophils ≥2%
• Biomarkers assessed:
  • 18 in sputum
  • 56 in serum/plasma
• Patients were grouped as:
  • Eos (with eosinophilia)
  • Non-Eos (without eosinophilia)

Results:

1. Patient Demographics
   1. Total patients: 180 with severe asthma
      1. Childhood-onset: 67 (37%; median age of onset: 5 years [Q1, Q3: 3, 12])
      2. Adult-onset: 113 (63%; median age of onset: 39 years [28, 49])
   2. Eosinophil Levels: Adult-onset asthma patients had:
      1. Higher blood eosinophils: 0.350 vs. 0.200 ×10⁹/L (adjusted-p (adj-p) = 0.013)
      2. Higher sputum eosinophils: 5.3% vs. 1.4% (adj-p = 0.002)
   3. FeNO and lung function showed no significant differences by age of onset.
   4. Comparison of Eosinophilic (Eos) vs Non-Eosinophilic (Non-Eos) Patients

5. Biomarker Correlations
   1. Biomarkers associated with sputum eosinophils in both groups:
   2. Sputum EDN, periostin, CCL17
   3. Serum IL-13
6. Lung function correlations:
   1. Childhood-onset: CCL17 and neutrophils
   2. Adult-onset: EDN and eosinophils

Conclusion:

While clinical presentation was similar across eosinophilic phenotypes in both onset groups, the underlying biomarker patterns differed. Notably, elevated sputum periostin was distinct to eosinophilic inflammation in adult-onset asthma, offering a potential differentiator for phenotype-specific management.

European Academy of Allergy and Clinical Immunology 2025,13-16 June, Glasgow, United Kingdom.