Differences in proteoglycan deposition in the airway of moderate and severe asthmatics

¹ Meakins-Christie Laboratories, Montreal Chest Institute, McGill University Hospital Centre
² Hôpital Sacre-Coeur, Univerité de Montréal, Montreal, Quebec, Canada

^* To whom correspondence should be addressed. E-mail: mara.ludwig{at}mcgill.ca.

	Abstract

Excess deposition of proteoglycans (PG) has been described in the sub-epithelial layer of the asthmatic airway wall. However, less is known about deposition in the airway smooth muscle (ASM) layer, and whether the pattern of deposition is altered depending upon disease severity.

Endobronchial biopsies were performed in patients with severe or moderate asthma (defined using ATS criteria) and in control subjects. Biopsies were immunostained for the PGs, biglycan, lumican, versican and decorin. PG deposition was measured in the subepithelial and ASM layers, the former by calculating the area of positive staining, and the latter, by determining the % area using point counting.

Immunostaining for PG was prominent in biopsies from both moderate and severe asthmatics, as compared to control subjects. While the amount of PG in the sub-epithelial layer was no different in the two asthmatic groups, the % area of biglycan and lumican in the ASM layer was significantly greater in moderate vs severe asthmatics (p<0.01 and 0.05, resp.).

Differences in the deposition of PG within the ASM layer of moderate vs severe asthmatics could potentially impact on the functional behaviour of the airway smooth muscle in these two groups of patients.

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