Anti‐tumor necrosis factor‐α antibody treatment reduces pulmonary inflammation and methacholine hyper‐responsiveness in a murine asthma model induced by house dust

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Abstract
Background/Aims Recent studies documented that sensitization and exposure to cockroach allergens significantly increase children's asthma morbidity as well as severity, especially among inner city children. TNF‐α has been postulated to be a critical mediator directly contributing to the bronchopulmonary inflammation and airway hyper‐responsiveness in asthma. This study investigated whether an anti‐TNF‐α antibody would inhibit pulmonary inflammation and methacholine (Mch) hyper‐responsiveness in a mouse model of asthma induced by a house dust extract containing both endotoxin and cockroach allergens. Methods A house dust sample was extracted with phosphate‐buffered saline and then used for immunization and two additional pulmonary challenges of BALB/c mice. Mice were treated with an intravenous injection of anti‐TNF‐α antibody or control antibody 1 h before each pulmonary challenge. Results In a kinetic study, TNF‐α levels within the bronchoalveolar lavage (BAL) fluid increased quickly peaking at 2 h while BAL levels of IL‐4, IL‐5, and IL‐13 peaked at later time‐points. Mch hyper‐responsiveness was measured 24 h after the last challenge, and mice were killed 24 h later. TNF inhibition resulted in an augmentation of these Th2 cytokines. However, the allergic pulmonary inflammation was significantly reduced by anti‐TNF‐α antibody treatment as demonstrated by a substantial reduction in the number of BAL eosinophils, lymphocytes, macrophages, and neutrophils compared with rat IgG‐treated mice. Mch hyper‐responsiveness was also significantly reduced in anti‐TNF‐α antibody‐treated mice and the pulmonary histology was also significantly improved. Inhibition of TNF significantly reduced eotaxin levels within the lung, suggesting a potential mechanism for the beneficial effects. These data indicate that anti‐TNF‐α antibody can reduce the inflammation and pathophysiology of asthma in a murine model of asthma induced by a house dust extract.