Effect of age on allergen-induced structural airway changes in brown Norway rats.

Abstract

It remains to be fully established whether allergen-induced airway inflammation and remodeling are influenced by age. The aim of the present study was to compare allergen-induced airway changes in young and adult rats. Brown Norway rats were sensitized at 4 weeks of age (young) or 13 weeks of age (adult) and exposed to aerosolized ovalbumin (OA) or phosphate-buffered saline for 2 weeks. In both age groups OA exposure induced an increase in OA-specific Immunoglobulin E and in the number of peribronchial eosinophils. OA-challenged animals also developed an increase in total airway wall area, enhanced fibronectin deposition, and goblet cell hyperplasia. Both inflammatory and structural alterations were more pronounced in the airways of young compared with adult OA-exposed rats. The number of peribronchial eosinophils was increased in young animals (685.4 +/- 75.0 versus 389.9 +/- 37.8/mm2 in adult rats; p < 0.001). A higher degree of goblet cell hyperplasia was observed in young rats (65.37 +/- 4.68 versus 34.74 +/- 3.68/mm basement membrane in adult rats; p < 0.001) and area of fibronectin deposition in the airway wall was higher in young compared with adult animals (5.08 +/- 0.46 versus 3.62 +/- 0.29 microm2/microm basement membrane; p < 0.005). In conclusion, in young rats airways are more susceptible to allergen-induced inflammatory and structural airway changes.