A critical role of Dectin-1 in hypersensitivity pneumonitis
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Objectives and design
Hypersensitivity pneumonitis (HP) is a pulmonary disease caused by repeated exposure to various aspiration antigens, including bacteria and fungi. Although TLRs are known to be required for the generation of HP triggered by bacteria, the significance of fungal receptors remains unclear. The present study aimed to investigate whether Dectin-1 and Dectin-2 contribute to the development of experimental HP triggered by the fungus Trichosporon asahii (T. asahii) that causes summer-type HP.
Materials and methods
We investigated the binding between Dectin-Fc protein and T. asahii by a dot blot assay. We performed the histological and flow cytometric analysis in the HP model using Dectin-1-deficient (Dectin-1−/−) and Dectin-2−/− mice. We also investigated Th17/Th1 responses in lung cells, and measured an IL-17-promoting cytokine IL-23 from bone marrow-derived dendritic cells (BMDCs) by ELISA.
Dectin-1 bound more strongly to T. asahii than Dectin-2. Dectin-1−/− mice barely developed HP, whereas both wild-type mice and Dectin-2−/− mice developed similar lung diseases. Dectin-1 deficiency decreased the infiltration of neutrophils and monocyte-derived macrophages and repressed the expansion of lung CD4+IL-17A+ cells. The production of IL-23 p19 was reduced in Dectin-1−/− BMDCs.
These data suggested Dectin-1 plays a critical role in the development of fungus-induced HP.
KeywordsDectin-1 Hypersensitivity pneumonitis Th17 Trichosporon asahii
We thank Ms. Hiromi Nakamura for technical assistance. This work was supported in part by Grant for Precursory Alumni Research (B) from Kanazawa Medical University (PR 2012-15 to M. H -K.). This work was also supported in part by a grant-in-aid from the Ministry of Education, Culture, Sports, Science and Technology of Japan (22590431 and 2546060 to A. N.).
Compliance with ethical standards
Conflict of interest
The authors have no financial conflict of interest.
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