Differential role of thymic stromal lymphopoietin in the induction of airway hyperreactivity and Th2 immune response in antigen-induced asthma with respect to natural killer T cell function.

Asthma is an inflammatory lung disease, in which CD1d-restricted natural killer T (NKT) cells play an important pathogenic role. Also, recent reports indicated that a cytokine, thymic stromal lymphopoietin (TSLP), is essential for the development of antigen-induced asthma. Here we examined the relationship between NKT cells and TSLP in a mouse model of asthma. NKT cells express TSLP receptor as well as IL-7 receptor alpha-chain. TSLP acts on NKT cells to preferentially increase their IL-13 production but not IFN-gamma and IL-4. In an allergen-induced asthma model, the development of airway hyperreactivity, a cardinal feature of asthma, was increased in TSLP transgenic mice, whereas this effect was not observed in TSLP transgenic mice lacking NKT cells. Interestingly, in the NKT cell-lacking TSLP transgenic mice, pulmonary eosinophilia and increase in IgE did not improve. Pulmonary lymphocytes from the NKT cell-lacking TSLP transgenic mice produced much less IL-13 upon CD3 stimulation than those from NKT cell-competent TSLP transgenic mice. These resultssuggest that, in allergen-induced asthma, TSLP acts on NKT cells to enhance airway hyperreactivity by upregulating their IL-13 production, whereas eosinophilia and IgE production are not influenced.