Airway remodeling of murine chronic antigen exposure model

Airway remodeling is one of the most important features of bronchial asthma. However, there are few studies that have used repeated antigen exposure in murine models. We designed a murine chronic antigen exposure model necessary for studying airway remodeling. Two different strains of mice, BALB/c mice and C57BL/6 mice, were sensitized and challenged for 3-7 weeks with ovalbumin (OVA). Bronchoalveolar lavage (BAL) and histology study were conducted in each phase. Morphometry was performed, and the epithelial area ratio (Ae ratio) and subepithelial area ratio (As ratio) were calculated. The Ae ratio and As ratio of BALB/c mice were significantly increased in sensitized mice compared with non-sensitized mice at 3 and 5 weeks, but not at 7 weeks. In C57BL/6 mice, the Ae ratio showed no significant changes, whereas the As ratio maintained high from 3 to 7 weeks. This thickening of the subepithelial layer consisted of collagen fibers with elastica van-Gieson (EVG) stain. Lymphocytes of the BAL showed a significant increase at 3 and 7 weeks in C57BL/6 mice, but not in BALB/c mice. A murine chronic OVA exposure model in C57BL/6 mice revealed subepithelial layer thickening consisting of collagen fibers and increased lymphocytes until 7 weeks. C57BL/6 mice are useful to elucidate the mechanism of airway remodeling.