Repeated Activation of Lung Invariant NKT Cells Results in Chronic Obstructive Pulmonary Disease-Like Symptoms

Chronic obstructive pulmonary disease (COPD) is characterized by chronic airway inflammation, mucus hypersecretion, and emphysema, which lead to reduced lung function and breathlessness. The pathologies of COPD are due to an abnormal immune response. Invariant natural killer T (iNKT) cells are an important population of innate lymphocytes and have been implicated in the regulation of immune responses associated with a broad range of diseases including COPD. We have here analyzed the role of iNKT cells in a model of COPD induced by repeated intranasal administration of iNKT cell agonist alpha-galactosylceramide (alpha-GalCer). Our results demonstrated that mice that received repeated intranasal administration of alpha-GalCer had molecular and inflammatory features of COPD including airway inflammation with significant increases in infiltration of macrophages and lymphocytes, CD8(+) T cells, as well as proinflammatory cytokines IL-6 and TNF-alpha. In particular, these mice also showed the presence of pulmonary emphysema, mucus production, and pulmonary fibrosis. Furthermore, neutralization of IL-4 reduced alpha-GalCer induced emphysema. This study indicates the importance of iNKT cells in the pathogenesis of COPD by an IL-4 dependent mechanism.