Objectives: Th2 cytokines such as interleukin (IL) 4 and IL-13 are potential mediators for mucus hypersecretion in allergic inflammation. To elucidate the functions of Th2 cytokines in allergic rhinitis, we examined the in vivo effects of the Th2 cytokine inhibitor suplatast tosilate on mucus hypersecretion and eosinophil infiltration in rat nasal epithelium.
Methods: We induced hypertrophic and metaplastic changes in goblet cells in the nasal epithelium of ovalbumin-sensitized rats by intranasal challenge with ovalbumin. The effects of orally administered suplatast tosilate on mucus production and eosinophil infiltration were examined.
Results: Suplatast tosilate (30 and 100 mg/kg) dose-dependently inhibited ovalbumin-induced mucus production and eosinophil infiltration. These suppressions of mucus production and eosinophil infiltration were only effective when suplatast tosilate was given in the effector phase; administration in the induction phase resulted in no effect.
Conclusions: These results indicate that Th2 cytokines are important mediators of mucus hypersecretion and eosinophil infiltration in allergic rhinitis. Suplatast tosilate may be useful for the treatment of allergic rhinitis by attenuating the inflammation of the effector phase.