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document
Bronchial matrix and inflammation respond to inhaled steroids despite ongoing allergen exposure in asthma . BACKGROUND Inflammatory and structural changes of the airway mucosa are chronic features of asthma . The mechanisms underlying these changes and their modulation by steroid prophylaxis have not been clarified . OBJECTIVE We postulated that asymptomatic ongoing allergen exposure could drive airway inflammation as well as changes in the extracellular matrix ( ECM ) , and that inhaled steroids could prevent this . METHODS Therefore , we exposed patients with mild asthma to 2 weeks of repeated low-dose allergen , with concomitant inhaled steroid or placebo treatment . Bronchial biopsies , which were taken before and after this exposure , were stained and digitally analysed . The ECM proteins in asthmatics were also compared with a normal control group . RESULTS Low-dose allergen exposure alone resulted in a significant increase of bronchial epithelial macrophages . Despite ongoing allergen exposure , inhaled steroids reduced the numbers of mucosal eosinophils , neutrophils and T lymphocytes . At baseline , the mean density of the proteoglycans ( PGS ) biglycan and decorin were , respectively , higher and lower in the bronchial mucosa of asthmatics as compared with normal controls . Steroid treatment , during allergen exposure , increased the mean density of the PGS biglycan and versican . CONCLUSION We conclude that chronic allergen exposure induces inflammatory changes in the bronchial mucosa . Despite ongoing allergen exposure , steroid treatment decreases mucosal inflammatory cells while altering PG density . The latter observation highlights the need to examine steroid-induced changes closely in the airway structure in patients with asthma .
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Intervention_Pharmacological
inhaled steroids
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Intervention_Pharmacological
steroid
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Intervention_Pharmacological
inhaled steroids
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Intervention_Pharmacological
low-dose allergen
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Intervention_Pharmacological
concomitant inhaled steroid
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Intervention_Control
placebo treatment
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Intervention_Pharmacological
steroids
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Intervention_Pharmacological
Steroid
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Intervention_Pharmacological
steroid
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Outcome_Physical
Bronchial matrix and inflammation
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Outcome_Physical
Inflammatory and structural changes of the airway mucosa
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Outcome_Physical
bronchial epithelial macrophages
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Outcome_Physical
numbers of mucosal eosinophils , neutrophils and T lymphocytes
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Outcome_Physical
density of the proteoglycans ( PGS ) biglycan and decorin
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Outcome_Physical
mean density of the PGS biglycan and versican
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Outcome_Physical
mucosal inflammatory cells
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Outcome_Other
steroid-induced changes
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Participant_Condition
asthma
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Participant_Condition
patients with mild asthma
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Participant_Condition
patients with asthma .