Plasminogen activator inhibitor-1 (PAI-1) and urokinase plasminogen activator (uPA) in sputum of allergic asthma patients

Urokinase plasminogen activator (uPA) and its inhibitor (PAI-1) have been associated with asthma. The aim of this study was to evaluate concentration of uPA and PAI-1 in induced sputum of house dust mite allergic asthmatics (HDM-AAs). The study was performed on 19 HDM-AAs and 8 healthy nonatopic controls (HCs). Concentration of uPA and PAI-1 was evaluated in induced sputum supernatants using ELISA method. In HDM-AAs the median sputum concentration of uPA (128 pg/ml; 95% CI 99 to 183 pg/ml) and PAI-1 (4063 pg/ml; 95%CI 3319 to 4784 pg/ml) were significantly greater than in HCs (17 pg/ml; 95%CI 12 to 32 pg/ml; p<0.001 and 626 pg/ml; 95%CI 357 to 961 pg/ml; p<0.001 for uPA and PAI-1 respectively). The sputum concentration of uPA correlated with sputum total cell count (r=0.781; p=0.0001) and with logarithmically transformed exhaled nitric oxide concentration (eNO) (r=0.486; p=0.035) but not with FEV1 or bronchial reactivity to histamine. On the contrary, the sputum PAI-1 concentration correlated with FEV1 (r=-0,718; p=0.0005) and bronchial reactivity to histamine expressed as log(PC20) (r=-0.824; p<0.0001) but did not correlate with sputum total cell count or eNO. The results of this study support previous observations linking PAI-1 with airway remodeling and uPA with cellular inflammation. Moreover, the observed effect of uPA seems to be independent of its fibrynolytic activity.