A number of innovative asthma therapies based on phenotypes have been developed, and clinical trial findings suggest encouraging outcomes. This study highlights the present state of knowledge about biomarkers for determining asthma phenotypes.

Because most innovative asthma medications target the T-helper type 2 (Th2) pathway, eosinophilic inflammation is the most emphasized phenotype. Instead of sputum eosinophil count, which is easily altered by corticosteroid medication, fractional-exhaled nitric oxide (FeNO) reflects an eosinophilic airway inflammation with a substantial association with a sputum eosinophilia and asthma severity. Some findings, however, demonstrated a discrepancy between treatment response or adjustment and FeNO levels. Serum periostin is a powerful serum biomarker for eosinophilic airway inflammation, as well as an indication of Th2-targeted treatment and airflow restriction. YKL-40 has been linked to asthma severity and airway remodeling. In addition, genomic and metabolomic approaches to asthma phenotypes and severity have been developed.


More research is needed to validate biomarkers such as FeNO and serum periostin, which depict eosinophilic airway inflammation, as well as eosinophil-derived neurotoxin and osteopontin (OPN). Asthma severity and airflow restriction are linked to periostin, YKL-40, OPN, and certain metabolites.