Rationale: There is increasing interest regarding asthma heterogeneity in relation to inflammatory patterns.
Objectives: To assess phenotypic characteristics, in particular clinical presentation of the disease, in 381 well-characterized adult asthmatics from the French Epidemiological study on the Genetics and Environment of Asthma (EGEA) according to their blood inflammatory pattern.
Methods: Four blood inflammatory patterns were defined according to eosinophil (EOS) and neutrophil (NEU) count cut-points. Samples with „d 250 EOS/mm3 were classified as EOShi and those with „d5000 NEU/mm3 as NEUhi. Clinical characteristics include typical asthma and COPD-like symptoms, as well as composite quantitative scores addressing the activity of the disease.
Measurements and Main Results: EOSlo pattern (<250 EOS/mm3) represented a substantial number of asthmatics (56.2%). Asthmatics with EOShi pattern had higher IgE, lower FEV1 and presented a more active asthma than those with EOSlo pattern. Among EOSlo, neutrophil inflammation (NEUhi) was related to less frequent positive skin prick test response (OR, 0.44; 95%CI, 0.20-0.96). Among EOShi, neutrophil inflammation did not explain current asthma or asthma activity, and was significantly related to nocturnal symptoms (OR, 5.21; 95%CI, 1.44-18.8) independently of age, sex, smoking and inhaled corticosteroid treatment. In non-smoker asthmatics, COPD-like symptoms, in particular chronic phlegm were more frequent in those with neutrophil inflammation, independent of eosinophil inflammation (OR, 2.35; 95%CI, 1.08-5.10).
Conclusions: Besides eosinophilia, neutrophil inflammation assessed in the blood is related to specific characteristics of asthma. Considering simultaneously neutrophilic and eosinophilic inflammation may contribute to help to disentangle that complex disease.