Matrix metalloproteinase-9, but not tissue inhibitor of matrix metalloproteinase-1, increases in the sputum from allergic asthmatic patients after allergen challenge.
OBJECTIVE
The aim of the study was to determine whether allergen inhalation modulates the levels of matrix metalloproteinase (MMP)-9 and tissue inhibitor of matrix metalloproteinase (TIMP)-1 in the induced sputum recovered from patients during a late-phase reaction.


METHODS
Eight allergic asthma patients and five healthy control subjects inhaled a dose of Dermatophagoides pteronyssinus extract corresponding to the provocative concentration of the allergen causing a 20% fall in FEV(1) and saline solution. Lung function was carefully monitored for 6 h, and an induced sputum test was performed at 6 h after sham challenge or allergen challenge. The total and differential cell counts were analyzed, and the levels of MMP-9 (by enzyme-linked immunosorbent assay [ELISA] and zymography), TIMP-1 (by ELISA), and albumin (by rocket immunoelectrophoresis) were measured.


RESULTS
The sputum eosinophil counts (p < 0.01) and MMP-9 levels (p < 0.05) increased significantly in atopic asthma patients after undergoing the allergen challenge but did not in the control subjects. By contrast, TIMP-1 and albumin levels were not significantly increased in any group. MMP-9 levels, measured after the allergen challenge in asthmatic patients, were significantly correlated with FEV(1) variations after allergen inhalation (r = 0.51; p < 0.05) and with the sputum neutrophil percentage (r = 0.71; p < 0.01).


CONCLUSIONS
The levels of MMP-9, but not TIMP-1, increase after inhaled allergen challenge in the sputum of allergic asthmatic patients. This protease increase may lead to a transient imbalance between MMP-9 and TIMP-1 favoring proteolytic extracellular matrix degradation.
Cataldo
Didier D
DD
Departments of Pneumology, University of Liège, Liège, Belgium. Didier.Cataldo@ulg.ac.be
Bettiol
Jane
J
Noël
Agnes
A
Bartsch
Pierre
P
Foidart
Jean-Michel
JM
Louis
Renaud
R
D000328:Adult; D001249:Asthma; D001985:Bronchial Provocation Tests; D005260:Female; D006801:Humans; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000032:analysis*; D008875:Middle Aged; D013183:Sputum / Q000737:chemistry* / Q000201:enzymology; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000032:analysis*
D019715:Tissue Inhibitor of Metalloproteinase-1; D020780:Matrix Metalloproteinase 9