Airway Wall Remodeling in Young and Adult Rats with Experimentally Provoked Bronchial Asthma

Abstract

Background: Airway wall remodeling is a typical finding in patients suffering from bronchial asthma. While morphological changes have been thoroughly described in adults, less is known about such changes in children because of the limited accessibility of relevant material. To overcome this constraint, animal asthma models may be used instead of human specimens. This study examined rats with artificially stimulated chronic asthma-like symptoms. Methods: Brown Norway rats of two age categories (young and adult) were sensitized by ovalbumin (OA), and their intrapulmonary airways (IA) were studied using morphometric and histochemical methods. Results: OA administration induced a significant increase in lung resistance in young animals but not in adults. The total IA wall area was significantly increased in both young and adult OA rats. In young animals, thickening of the adventitia played a more crucial role in this increase than it did in adults, in which the mucosa and the submucosa participated to a higher degree. The IA walls of young OA rats had significantly higher levels of infiltrating eosinophils than those of adult OA animals. The multiplication of goblet cells was more pronounced in adult rats, which was associated with a tendency to produce a higher proportion of acidic glycoconjugates. Conclusions: OA stimulation affected the IA of young rats differently than those of adult animals. Changes in the outer IA layer of young rats can be triggered by activated eosinophils; however, stimulated airway epithelium can be a source of factors that influence the inner IA layers in adult rats.

Parabromophenacyl Bromide Inhibits Subepithelial Fibrosis by Reducing TGF-β₁ in a Chronic Mouse Model of Allergic Asthma

“…Airway remodeling in asthma, a complex event, is characterized by several features such as subepithelial fibrosis, airway inflammation, smooth-muscle hyperplasia, mucous-gland hypertrophy, goblet cell metaplasia and angiogenesis [30,31]. However, the relations between these various phenotypes are not straightforward.…”

Effect of P2X4R on airway inflammation and airway remodeling in allergic airway challenge in mice

“…Pathological changes in the lung and bronchial tissues were observed and images were captured using a BX-60 microscope (Olympus, Tokyo, Japan). The tissues were scored based on the presence of inflammatory cells, using the following scale: Absent (0), rare ( 1 ), mild ( 2 ), moderate ( 3 ) or severe ( 4 ). Scoring was performed by an observer in a blinded-manner.…”

Age dictates a steroid-resistant cascade of Wnt5a, transglutaminase 2, and leukotrienes in inflamed airways

“…4,5 Consistent with the increase in markers of airway eosinophilia in human neonates, 6 rodent models of airway inflammation have shown that airway eosinophilia is increased in neonates. [7][8][9] However, despite increased eosinophilia at a young age, changes in airway structural cells are more severe later in life. 7,9 Leukocytes, which infiltrate the respiratory tissue of allergic and asthmatic patients, produce cytokines, such as IL-4, IL-13, IL-5 and TGF-b1, which promote inflammation and remodeling.…”

“…[7][8][9] However, despite increased eosinophilia at a young age, changes in airway structural cells are more severe later in life. 7,9 Leukocytes, which infiltrate the respiratory tissue of allergic and asthmatic patients, produce cytokines, such as IL-4, IL-13, IL-5 and TGF-b1, which promote inflammation and remodeling. 10 In addition, myeloid cells produce lipid mediators, such as leukotrienes (LTs), which perpetuate inflammatory cell recruitment and remodeling.…”