Intranasal pretreatment with toll like receptor 9 ligand CpG oligodeoxynucleotides prevents the development of allergic rhinitis in juvenile guinea pigs

Objective To evaluate the therapeutic effect of intranasal oligodeoxynucleotides with CpG motifs （CpG ODN） in prevention of allergic rhinitis in juvenile guinea pigs. Methods Juvenile guinea pigs aged from 7 to 10 weeks were administrated with CpG ODN alone or combined with OVA at single dose concentration intranasally （on day 0, 5, 10, 15 in sequence） while control and blank group were administrated with saline. Both experimental and control animals were again sensitized by OVA （on day 18, 25）, and 14 days after second sensitization animals were challenged by OVA intranasally （on days 39 and 46）. Two hours after challenge, the animals were sacrificed. Then Hemotoxin and Eosin stain were carried out to analyze local eosinophilic reactions and nasal lesions. Local and systemic cytokines interleukin IL-5 and IFN-γ levels were examined by ELISA. Immunoflourescence was carried out with ICAM-1 antibody. Statistical analysis was performed using a SPSS 11.0 software. Results In CpG ODN-administration or CpG ODN with OVA-administration group allergic rhinitis symptoms were not as severe as model control group （P<0.05）. Compared with the model control group, CpG ODN-administration did not increase production of OVA-specific Thl cytokine IFN-γ but decreased productions of ovalbumin-specific Th2 cytokines IL-5 both in serum and nasal specimen（q value were 3.890 and 4.019, P<0. 05）. Moreover, nasal lesions with infiltration of mean （x ±s） eosinophils（20. 0 ±9. 6） in CpG group animal were prominently reduced by the CpG ODN-treatment compared with the control animals （53. 5 ± 19. 8） and CpG ＋ OVA group （9. 5 ±5. 7） were lower than CpG-M ＋ OVA group （49. 2 ± 18. 9）, the differences were significant （q value were 3.785 and 4. 576, P <0. 05）. Immunoflourescence results showed lower ICAM-1 expression in nasal specimen of CpG group compared with model group and CpG plus OVA group animal to CpG mimics plus OVA group （Z value were 3.697 and 3.765, P < 0.05 ）. Conclusions Intranasal administration of CpG oligodeoxynucleotides with or without allergen may be an effective way to prevent the development of allergic rhinitis. Key words: Rhinitis,allergic; Oligodeoxyribonucleotides; guinea pigs; Toll-like receptor 9