Sputum ADAM 8 expression is increased in severe asthma and COPD

Summary Background Severe asthma and chronic obstructive pulmonary disease ( COPD ) are chronic inflammatory airway diseases in which the mechanisms are not fully understood. A disintegrin and metalloproteinase domain 8 ( ADAM 8) is an enzyme expressed on most leucocytes and may be important for facilitating leucocyte migration in respiratory disease. Objective To investigate ADAM 8 mRNA and protein expression in asthma and COPD and its relationship between asthma severity and inflammatory phenotypes. Methods Induced sputum was collected from 113 subjects with asthma (severe n  = 31, uncontrolled n  = 39 and controlled n  = 35), 20 subjects with COPD and 21 healthy controls. Sputum ADAM 8 mRNA expression was measured by qPCR , and soluble ADAM 8 ( sADAM 8) protein was measured in the sputum supernatant by validated ELISA . Results ADAM8 mRNA correlated with ADAM 8 protein levels ( r  = 0.27, P  < 0.01). ADAM8 mRNA ( P  = 0.004) and sADAM 8 protein ( P  = 0.014) levels were significantly higher in both asthma and COPD compared with healthy controls. ADAM8 mRNA ( P  = 0.035) and sADAM 8 protein ( P  = 0.002) levels were significantly higher in severe asthma compared with controlled asthma. Total inflammatory cell count ( P  < 0.01) and neutrophils ( P  < 0.01) were also elevated in severe asthmatic sputum. Although ADAM 8 mRNA was significantly higher in eosinophilic and neutrophilic asthma ( P  < 0.001), sADAM 8 did not differ between asthma inflammatory phenotypes. ADAM8 expression positively correlated with sputum total cell count and sputum neutrophils. Conclusions and Clinical Relevance ADAM 8 expression is increased in both severe asthma and COPD and associated with sputum total cell count and neutrophils. ADAM 8 may facilitate neutrophil migration to the airways in severe asthma and COPD .