Background: Allergic rhinitis (AR) and asthma are 2 entities of allergic airway diseases that frequently occur together, which is referred to as united airways. In contrast to this general concept, we hypothesized that innate immunity of the upper and lower airways is respectively distinctive, because the immunologic conditions of the nasal and lung mucosa as well as the functions of the immune cells within their epithelia are different. Objective: We wanted to identify distinctive mechanisms of innate immunity in the nose and lung mucosa, which are responsible for house dust mite (HDM)-induced AR and allergic asthma (AA), respectively. Methods: We constructed a mouse model of AR or AA induced by sensitization and consequent provocation with HDM extracts. Results: HDM-derived β-glucans, rather than LPS, were proven to be essential to activating innate immunity in the nasal mucosa and triggering AR, which depended on Toll-like receptor 2 (TLR2), but not on TLR4; however, the LPS/TLR4 signaling axis, rather than β-glucans/TLR2, was critical to HDM-induced AA. These differences were attributed to the specific role of β-glucans and LPS in inducing the surface expression of TLR2 and TLR4 and their translocation to lipid rafts in nasal and bronchial epithelial cells, respectively. We also showed that dual oxidase 2-generated reactive oxygen species mediate both β-glucan-induced TLR2 activation and LPS-induced TLR4 activation. Conclusions: We describe a novel finding of distinctive innate immunity of the nose and lungs, respectively, which trigger AR and AA, by showing the critical role of HDM-induced TLR activation via dual oxidase 2-mediated reactive oxygen species.
Bibliographical noteFunding Information:
Disclosure of potential conflict of interest: J.-H. Ryu has received grants from the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education, Science, and Technology and Yonsei University College of Medicine. J.-H. Yoon has received grants from the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education, Science, and Technology. The rest of the authors declare that they have no relevant conflicts of interest.
Supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology (grant 2012-0000803 to J.-H.Y. and grant 2010-0022899 to J.-H.R.) and by the Yonsei University College of Medicine (grant 6-2009-0115 to J.-H.R.). None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript.
All Science Journal Classification (ASJC) codes
- Immunology and Allergy