Katoh S, et al. – In this study, researchers assessed biomarkers to differentiate asthma from chronic obstructive pulmonary disease (COPD). Analyzing blood eosinophil counts and fractional exhaled nitric oxide (FeNO) levels, they compared patients with asthma (n=60), including atopic-asthma (n=30) and non-atopic asthma (n=30), and patients with COPD (n=30) with respect to serum periostin, interleukin-25 (IL-25), and immunoglobulin E (IgE) concentrations. Asthmatics vs patients with COPD exhibited remarkably higher peripheral blood eosinophil counts, FeNO levels, and total serum IgE concentrations, but not serum periostin or serum IL-25 concentrations. Patients with atopic-asthma vs those with non-atopic asthma and COPD had increased serum periostin and IgE concentrations. The investigators noted a significant correlation of FeNO levels with the peripheral blood eosinophil counts and serum IL-25 concentrations in asthmatics. Overall, for discriminating asthma and COPD, utility of FeNO levels and peripheral blood eosinophil counts as biomarkers was evident. Serum periostin and IgE concentrations could be biomarkers for atopic asthma.