Asthma Inflammatory Phenotypes: How Can We Distinguish Them?

Area of Science:

• Pulmonology
• Immunology
• Biochemistry

Background:

• Induced sputum is underutilized for routine asthma phenotyping.
• Identifying inflammatory asthma phenotypes is key for targeted treatment.
• Biomarkers can differentiate asthma subtypes and guide therapy.

Purpose of the Study:

• Determine the prevalence of inflammatory asthma phenotypes using induced sputum.
• Identify biomarkers to distinguish between these phenotypes.
• Evaluate biomarker utility in patients with and without biologic therapy.

Main Methods:

• Cross-sectional study of 80 asthma patients.
• Assessed clinical data, asthma control, skin prick tests, impulse oscillometry, spirometry, induced sputum, and various biomarkers (IgE, eosinophils, FeNO, periostin, IL-5, IL-6, IL-8, IL-17A, IL-33).
• Included 17 patients on biologic therapy (omalizumab or benralizumab).

Main Results:

• Eosinophilic asthma (EA) and mixed granulocytic asthma (MGA) were most prevalent (31% and 30%).
• Blood eosinophil counts (≥ 240/μL) identified EA with 64% sensitivity and 72.7% specificity.
• Elevated IL-8 associated with neutrophilic asthma (NA); higher IL-17A linked to EA without biologics.
• Biologic-treated EA showed higher IL-5; MGA on biologics had higher IL-5, IL-6, and IL-8.

Conclusions:

• EA and MGA are the predominant asthma inflammatory phenotypes.
• Blood eosinophil counts are a reliable biomarker for identifying EA, irrespective of biologic use.
• A comprehensive biomarker panel, beyond clinical profiles, is essential for optimal asthma management.