Effect of sublingual immunotherapy on antigen-induced bronchial and nasal inflammation in mice

Sublingual immunotherapy (SLIT) is effective in the treatment of a variety of allergic diseases, including bronchial asthma and rhinitis. However, how this local therapy exerts such wide effects is unclear. In this study, we comparatively examined the effect of SLIT on antigen-induced airway inflammation in bronchoalveolar and nasal cavities in mice.

Mice were treated sublingually with ovalbumin (OVA) once a day for 2 weeks. Subsequently, they were immunized with the corresponding antigen. Following intratracheal and nasal challenge with OVA, infiltration of inflammatory cells into the bronchoalveolar and nasal cavities was investigated in these mice.

Massive infiltration of eosinophils as well as neutrophils into the bronchoalveolar cavity was induced by intratracheal OVA challenge. Eosinophils accumulated in the nasal cavity, but the number of neutrophils did not significantly change in response to nasal antigen challenge. These antigen-induced airway inflammatory responses, including the increases in the numbers of eosinophils and/or neutrophils in the bronchoalveolar and nasal cavities, were clearly suppressed by SLIT.

This animal model displaying differential inflammatory responses in the bronchoalveolar and nasal cavities may be useful to elucidate the efficacy and mechanisms of SLIT against various allergic diseases.