IL-17-mediated regulation of innate and acquired immune response against pulmonary Mycobacterium bovis bacille Calmette-Guerin infection

M Umemura, A Yahagi, S Hamada… - The Journal of …, 2007 - journals.aai.org
M Umemura, A Yahagi, S Hamada, MD Begum, H Watanabe, K Kawakami, T Suda, K Sudo…
The Journal of Immunology, 2007journals.aai.org
IL-17 is a cytokine that induces neutrophil-mediated inflammation, but its role in protective
immunity against intracellular bacterial infection remains unclear. In the present study, we
demonstrate that IL-17 is an important cytokine not only in the early neutrophil-mediated
inflammatory response, but also in T cell-mediated IFN-γ production and granuloma
formation in response to pulmonary infection by Mycobacterium bovis bacille Calmette-
Guérin (BCG). IL-17 expression in the BCG-infected lung was detected from the first day …
Abstract
IL-17 is a cytokine that induces neutrophil-mediated inflammation, but its role in protective immunity against intracellular bacterial infection remains unclear. In the present study, we demonstrate that IL-17 is an important cytokine not only in the early neutrophil-mediated inflammatory response, but also in T cell-mediated IFN-γ production and granuloma formation in response to pulmonary infection by Mycobacterium bovis bacille Calmette-Guérin (BCG). IL-17 expression in the BCG-infected lung was detected from the first day after infection and the expression depended on IL-23. Our observations indicated that γδ T cells are a primary source of IL-17. Lung-infiltrating T cells of IL-17-deficient mice produced less IFN-γ in comparison to those from wild-type mice 4 wk after BCG infection. Impaired granuloma formation was also observed in the infected lungs of IL-17-deficient mice, which is consistent with the decreased delayed-type hypersensitivity response of the infected mice against mycobacterial Ag. These data suggest that IL-17 is an important cytokine in the induction of optimal Th1 response and protective immunity against mycobacterial infection.
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