The relationship between airways inflammation and asthma severity

In order to investigate the relationship between airways inflammation and d isease severity, and improve the understanding of persistent asthma, 74 ast hmatics, with disease severity ranging from intermittent, to mild to modera te and severe persistent (classified according to the Global Initiative for Asthma [GINA] guidelines), and 22 nonatopic control subjects were studied using the method of induced sputum. Sputum was analyzed for total and diffe rential cell counts concentrations of albumin, and levels of eosinophil cat ionic protein (ECP), myeloperoxidase (MPO), and tryptase, inflammatory medi ators reflecting eosinophil, neutrophil, and mast cell activation. Asthma s everity (assessed by FEV1, peak expiratory flow [PEF] variability, and dail y symptom scores) and methacholine airways responsiveness were related to s putum eosinophilia and ECP. In addition, sputum neutrophilia and MPO levels correlated, albeit weakly, with PEF variability and symptom scores, respec tively. Tryptase concentrations were raised in mild to moderate asthmatics. Albumin concentrations were significantly raised across the spectrum of as thma severity and correlated with those of tryptase and ECP. Despite treatm ent with either high doses of inhaled corticosteroids or oral corticosteroi ds, prominent eosinophilic inflammation with raised ECP was noted. This stu dy points to persistent, disease severity-related airways inflammation in a sthma, involving eosinophils, mast cells, and neutrophils, which is evident despite treatment with corticosteroids.