Disparate Features Of Allergic Airway Disease Between Young And Old Mice

The prevalence of asthma in the elderly (>;65) is increasing and associated with higher mortality than in children or young adults. Despite this increase, the effects of age on the development, character and severity of allergic asthma have been understudied. To elucidate the influence of age on allergic airway disease, we compared pulmonary responses of young (10‐week) and old (14‐month) BALB/c mice that were intranasally sensitized and challenged with house dust mite extract (HDM). After challenge, bronchoalveolar lavage fluid (BALF) was collected for cell and cytokine analysis and lung tissue was processed for gene expression analysis and histopathology. Both young and old mice developed HDM‐induced allergic airway disease. This was manifested by the presence of BALF eosinophlis and Th2 cytokines (IL5, IL13), as well as elevated gene expression of eotaxin, chitinase 3‐like 4 and airway mucus regulating genes Gob5 and Muc5AC. Compared to young mice, old mice had a significantly greater pulmonary allergic response (e.g., 10 × more eosinophils and IL13). In addition, only old mice showed a Th17 immune response to HDM characterized by increased BALF neutrophils and IL17, IL6 and KC cytokines. These results suggest that the severity and character of allergic airway disease is age dependent and the elderly may be prone to develop more severe allergic asthma with a mixed Th2/Th17 immune response. USEPA RD83479701