Uzan GC, et al. - Researchers assessed pulmonary functions in asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) patients in correlation with inflammatory markers such as cysteinyl leukotrienes (cys-LTs), prostaglandin D2 (PG-D2), prostaglandin E2 (PG-E2), interleukin 5 (IL-5), and a disintegrin and metalloprotease domain (ADAM 33). They found a negative correlation of PG-D2, cys-LTs, and ADAM33 levels with FEV1/FVC% values in ACOS patients. PG-E2 and FEV1/FVC% were negatively correlated, whereas positive correlations were found between IL-5 and pulmonary function tests, including FVC, FVC%, FEV1, FEV1%, FEF25-75, and FEF25-75% in COPD patients. A negative correlation of cys-LTs levels with FEV1 and FEF25-75 values was also identified in asthma patients. Findings are indicative of the possible value of PG-D2 levels as a biomarker to discriminate COPD in asthma and ACOS patients.