Methods: BALB/c mice were divided into 4 groups: control, allergic rhinitis (AR), oral tolerance (OT) , and OT with anti-IL-9 antibody (OT + IL9AB) group. All mice except control group were sensitized with ovalbumin (OVA) three times for two weeks consecutively. After two weeks, mice in OT and OT + IL9AB group underwent immunotherapy by feeding of OVA. During the immunotherapy, mice in OT + IL9AB group were injected with purified anti-mouse IL-9 antibody. All sensitized mice were challenged intranasally with OVA. Allergic symptoms, eosinophil counts in nasal mucosa and serum OVA-specific IgE were measured. Interferone-γ, IL-4, IL-17, IL-10, TGF-ß, T-bet, GATA-3, ROR- γ t, PU.1 and Foxp3 mRNA expression in nasal mucosa determined by real-time polymerase chain reaction. Flow cytometry of CD4+CD25+Foxp3+ T cells in spleen was analyzed.
Results: In OT and OT + IL9AB group, symptom score, serum OVA-specific IgE, eosinophils, IL-4, PU.1 and GATA-3 mRNA were decreased (p<0.05), and IL-10, Foxp3 mRNA, and CD4+CD25+Foxp3+ T cells were increased compared with those in AR group (p<0.05). In OT + IL9AB group, symptom score and serum OVA-specific IgE were lower than those in OT group (p<0.05). Foxp3 mRNA and CD4+CD25+Foxp3+ T cells were higher than those in OT group (p<0.05).
Conclusions: Administration of anti-IL-9 antibody increased the induction of tolerance in a mouse model of allergic rhinitis. These results indicate that anti-IL-9 antibody have immunomodulatory effect on immune tolerance in allergic rhinitis model.