Intralymphatic treatment of flagellin–ovalbumin mixture reduced allergic inflammation in murine model of allergic rhinitis

Background Bacterial flagellin, a Toll‐like receptor 5 agonist, is used as an adjuvant for immunomodulation. In this study, we aimed to evaluate the effect and its mechanism following intralymphatic administration of OVA‐flagellin (FlaB) mixture in the mouse model of allergic rhinitis. Materials and Methods BALB/c mice were sensitized with OVA and treated with an OVA‐FlaB mixture via intranasal, sublingual, and intralymphatic routes to evaluate the effect of each treatment. Several parameters for allergic inflammation and its underlying mechanisms were then evaluated. Results Intralymphatic injection of the OVA‐FlaB mixture reduced symptom scores, eosinophil infiltration in the nasal mucosa, and total and OVA‐specific IgE levels more significantly than intranasal and sublingual administration. Systemic cytokine (IL‐4, IL‐5, IL‐6, IL‐17, and IFN‐γ) production and local cytokine (IL‐4 and IL‐5) production were also reduced significantly after intralymphatic injection with OVA‐FlaB. Double intralymphatic injection of the mixture was more effective than single injection. Moreover, the expression of innate cytokines such as IL‐25 and IL‐33 in nasal epithelial cells was reduced, and the expression of chemokines such as CCL24 (eotaxin‐2), CXCL1, and CXCL2 was decreased in the nasal mucosa, suggesting the underlying mechanism for intralymphatic administration of the OVA‐FlaB mixture. Conclusion Intralymphatic administration of an OVA‐FlaB mixture was more effective in alleviating allergic inflammation than intranasal and sublingual administration in a mouse model of allergic rhinitis. This effect may be attributed to the reduced expression of innate cytokines and chemokines. This treatment modality can be considered as a new therapeutic method and agent.