George L, Taylor AR, Esteve-Codina A, et al. - In order to clarify if the clinical or pathophysiologic importance of the “treatable trait” high blood eosinophil count in chronic obstructive pulmonary disease (COPD) is the same as for asthma, researchers analyzed bronchial brushings from individuals with COPD and asthma to examine the link between the blood eosinophil count, clinical features and gene expression. They recruited the individuals into a COPD (emphysema vs airway disease [EvA]) or asthma cohort (Unbiased BIOmarkers in PREDiction of respiratory disease outcomes, U-BIOPRED). They found elevated total serum IgE in eosinophilic asthma and COPD. They identified a statistically significant positive link of 12 genes, in EvA, with the linear blood eosinophil count, whereas significant links (266 positive and 931 negative) were shown by 1197 genes in U-BIOPRED. Slight overlapping between genes and pathways related to blood eosinophil counts in asthma vs COPD was demonstrated by the transcriptome. Eosinophilic asthma and COPD had only CST1 (cystatin SN) in common, which was replicated in independent cohorts. Between asthma and COPD, shared “treatable traits” do exist, but the molecular mechanisms underlying these conditions are predominately different.