Intranasal azelastine and mometasone exhibit a synergistic effect on a murine model of allergic rhinitis

Abstract Purpose The purpose of this study was to compare the anti-allergic effects of the combination of azelastine and mometasone with those of either agent alone in a Dermatophagoides farinae (Derf)-induced murine model of allergic rhinitis (AR). Materials and methods Forty BALB/c mice were divided into five groups: azelastine (A), mometasone (M), a combination of azelastine and mometasone (MA), Derf, and control. Derf served as the allergen. Allergic symptom scores, eosinophil counts, and serum Derf-specific IgE levels were measured. The mucosal levels of mRNAs encoding interferon (IFN)-γ, T-bet, interleukin (IL)-4, GATA-3, Foxp3, IL-17, and ROR-γt were determined by real-time polymerase chain reaction. The T-bet, GATA-3, Foxp3, and ROR-γt results were confirmed by Western blotting. Results Nose-rubbing motions; the levels of mRNAs encoding IL-4, GATA-3, and ROR-γt; and tissue eosinophil count were reduced in the MA compared with those in the Derf group (all P values < 0.05). The levels of mRNAs encoding GATA3 and IL-4 mRNA [synthesized by T helper (Th)2 cells] were reduced and that of mRNA encoding Foxp3 was increased in the MA compared with those in the Derf and A groups. Western blotting confirmed these findings. Conclusion We found that the combination of intranasal azelastine and mometasone synergistically suppressed Th17 responses and (reciprocally) elevated Treg responses. Therefore, this combination not only ameliorated allergic inflammation by suppressing Th2 responses, but also usefully modified the Treg/Th17 balance.