Cold air and air pollution induce bronchial hyperresponsiveness and inflammation in a murine model

BALB/c mice exhibit more pronounced bronchial hyperresponsiveness and neutrophilic inflammation compared to C57BL/6 mice. Submaximal exercise of BALB/c mice at 4 °C induced acute changed breathing patterns early in the exercise protocol. 24 h after the last running session, bronchial hyperresponsiveness to increasing concentrations of methacholine (with both saline and DEP exposure) was observed. When DEP exposure was added to exercise at 4 °C, small airway resistance was significantly increased, neutrophilic airway inflammation was induced and type 2 dendritic cells were more abundantly present in the lungs. Proinflammatory cytokines (TNF-α, MCP-1, KC and GM-CSF) in bronchoalveolar lavage were significantly increased and leakage of surfactant protein D to serum was enhanced in DEP-exposed animals, exercising at 4 °C. In DEP-exposed mice, macrophages were more loaded with DEP at 4 °C, exercise or both.