The relationship between inflammatory markers and spirometric parameters in ACOS, Asthma, and COPD.

: The inflammatory mechanisms underpinning asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) have not been fully elucidated. Here, we examined the levels of cysteinyl leukotrienes (cys-LTs), prostaglandin D2 (PG-D2), prostaglandin E2 (PG-E2), interleukin 5 (IL-5), and a disintegrin and metalloprotease domain (ADAM 33) in ACOS patients to determine the relationship between levels of these inflammatory markers and pulmonary functions.: Blood samples were obtained from asthma, COPD, and ACOS patients who received combined therapy and were stable for the last month to measure cys-LTs, PG-D2, PG-E2, IL-5, and ADAM33 levels. Differences between groups and their correlations with pulmonary function tests were evaluated.: In total, 24 ACOS, 27 asthma, and 35 COPD patients were included. . PG-D2 levels were higher in ACOS (120.9 ± 117.2 ng/L) and asthma (119.6 ± 111.7 ng/L) patients than in COPD (82.6 ± 46.7 ng/L) patients (p = 0.036 and p = 0.038, respectively). In ACOS patients, PG-D2, cys-LTs, and ADAM33 levels were negatively correlated with FEV1/FVC% values ( = 0.021,  = 0.008, and  = 0.028, respectively). In COPD patients, a negative correlation was detected between PG-E2 and FEV1/FVC% ( = 0.007), whereas positive correlations were detected between IL-5 and pulmonary function tests, including FVC, FVC%, FEV1, FEV1%, FEF25-75, and FEF25-75% ( = 0.047,  = 0.005,  = 0.002,  = 0.002,  = 0.010, and  = 0.005, respectively). In asthma patients, cys-LTs levels were negatively correlated with FEV1 and FEF25-75 values ( = 0.045 and  = 0.037, respectively).: PG-D2 levels may be a valuable biomarker to differentiate COPD in asthma and ACOS patients.