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Peptidase activities in serum and bronchoalveolar lavage fluid from allergic asthmatics — comparison with healthy non‐smokers and smokers and effects of inhaled glucocorticoids
Author(s) -
van der Velden,
Brigitta A. E. Naber,
Van Hal,
Overbeek,
Hoogsteden,
Versnel
Publication year - 1999
Publication title -
clinical and experimental allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 154
eISSN - 1365-2222
pISSN - 0954-7894
DOI - 10.1046/j.1365-2222.1999.00550.x
Subject(s) - bronchoalveolar lavage , medicine , asthma , neprilysin , fluticasone propionate , immunology , pathogenesis , aminopeptidase , inhalation , dipeptidyl peptidase , endocrinology , enzyme , lung , chemistry , anesthesia , biochemistry , leucine , amino acid
Background Neuropeptides may be involved in the pathogenesis of asthma by evoking neurogenic inflammation. Since the effects of neuropeptides are limited by peptidases, reduced activity of peptidases may contribute to the inflammatory process. Objective We hypothesized that soluble peptidase activities are decreased in asthmatics and that inhaled glucocorticoids exert part of their anti‐inflammatory action by increasing soluble peptidase activities. Methods Serum and bronchoalveolar lavage (BAL) fluid was obtained from non‐smoking and smoking volunteers and from allergic asthmatics both before and after treatment for 12 weeks with placebo or inhaled fluticasone propionate. Activities of neutral endopeptidase (NEP), aminopeptidase N (APN) and dipeptidyl peptidase IV (DPP IV) were determined using colourometric assays. Results Reduced DPP IV activity in serum and reduced NEP activity in BAL fluid were found in healthy smokers compared with non‐smokers. In contrast, no differences in peptidase activities in serum or BAL fluid were observed between allergic asthmatics and healthy non‐smokers. Fluticasone propionate treatment did not affect peptidase activities in the asthmatic patients. Conclusions We conclude that reduced peptidase activities in serum or BAL fluid can be found in healthy smokers, but not in allergic asthmatics, and that inhaled glucocorticoids do not affect peptidase activities in BAL fluid or serum of asthmatics. Our results do not support the hypothesized dysfunction of peptidases in the asthmatic airways.