Increased glycosaminoglycans in the urine of asthmatic children on inhaled corticosteroids

Increased extracellular matrix (ECM) deposition in the airway wall contributes to the airway remodeling in asthmatics. Glycosaminoglycans (GAGs) are polysaccharides attached to a protein core in order to form proteoglycans, a component of the ECM. In this study, we investigated the possible influence of long-term treatment with inhaled corticosteroids (ICS) on urinary GAGs levels of asthmatic children. Seventy asthmatic children (41 boys), aged 6.8-12.5 yr, participated in the study. About 44 were treated with inhaled budesonide via turbuhaler for 2-35 months (median 12 months) and 26 were on relief medications. About 30 healthy controls were also studied. GAGs were precipitated from early morning urine samples, collected, isolated and quantified using uronic acid-carbazole reaction and expressed as uronic acid (UA) in mu g/g/Cr-u/m(2). Urinary GAGs values did not differ significantly between controls and asthmatics but significant differences were found between children on ICS and asthmatics on relief medications (p < 0.001). There was a positive correlation between the daily dose of inhaled budesonide and the urinary GAGs values (r = 0.32, p = 0.037) whereas a threshold distinguishing 'low' vs. 'high' doses of ICS was found to be at 300 mu g/m(2) per day with a significant difference in urinary GAGs secretion (p = 0.006). Our data show that urinary GAGs secretion is reduced in asthmatic children that used only relief medication but it is increased in those on long-term treatment with ICS. A dose dependent effect of ICS was also detected.