Enhanced proteoglycan deposition in the airway wall of atopic asthmatics

Increased extracellular matrix (ECM) deposition in the airway wall contribu tes to the airway wall remodeling observed in asthmatics. Although alterati ons in collagen have been well described, less is known about changes in ot her components of the ECM, particularly proteoglycans (PGs). Endobronchial biopsies were obtained from seven patients with mild atopic asthma and six normal control subjects. Tissues were blocked in OCT and frozen in isopenta ne. Sections were immunostained with antibodies for the small leucine-rich PGs, lumican, biglycan, decorin, and fibromodulin and for versican, a large chondroitin sulfate PG. We calculated the area of positive staining in the subepithelial layer, correcting for basement membrane length. Lumican, big lycan, and versican were localized predominantly in the subepithelial layer of the airway wall in all groups. PG deposition was significantly increase d in asthmatics as compared with that in control subjects. Furthermore, the degree of PG immunoreactivity was significantly correlated with airway res ponsiveness in the asthmatics (lumican; r = -0.77, p < 0.05; biglycan: r = -0.76, p < 0.05; versican: r = -0.74, p = 0.06). Our results suggest that P Gs may play a role in airway wall remodeling and thereby, airway mechanics in asthma.