CD4⁺ T-lymphocytes regulate airway remodeling and hyper-reactivity in a mouse model of chronic asthma

Asthma is an acute-on-chronic inflammatory disease of the airways, characterized by airflow obstruction and hyper-reactivity of the airways to a variety of stimuli. Chronic asthma is associated with remodeling of the airway wall, which may contribute to hyper-reactivity and fixed airflow obstruction. We used an improved mouse model of chronic asthma to investigate the role of CD4⁺ T-lymphocytes in airway remodeling and hyper-reactivity. Animals functionally depleted of CD4⁺ T-lymphocytes by repeated administration of a monoclonal antibody exhibited markedly decreased airway responsiveness. In addition, these mice had greatly diminished subepithelial fibrosis, epithelial thickening, and mucous cell hyperplasia/metaplasia. Chronic inflammation in the airway wall was moderately reduced, with a marked decrease in the accumulation of immunoglobulin- synthesizing plasma cells. However, intraepithelial accumulation of eosinophils was not significantly inhibited and airway epithelial expression of eotaxin was undiminished. This work provides the first experimental evidence that CD4⁺ T-lymphocytes play a crucial role in the pathogenesis of the lesions of chronic asthma and lends support to the notion that functional inhibition of these cells may be an important therapeutic target.