The C-C chemokine receptor 6 (CCR6) is crucial for Th2-driven allergic conjunctivitis

- Allergic conjunctivitis from an allergen-driven Th2 response is characterized by conjunctival eosinophilic infiltration.
- CCR6 KO mice were significantly protected from EAC and neutralization of CCL20 inhibits the development of EAC.
- Neutralization of CCR6 ligand, CCL20 inhibits the development of experimental allergic conjunctivitis.

Allergic conjunctivitis from an allergen-driven Th2 response is characterized by conjunctival eosinophilic infiltration. Although CCL20-CCR6 axis has been reported to play a proinflammatory role in several murine models of autoimmune diseases including allergic diseases, their underlying mechanism needs to be investigated. We here examined whether CCL20-CCR6 axis could play a role in the development of allergic conjunctival inflammation using murine experimental allergic conjunctivitis (EAC) model induced by ovalbumin (OVA) allergen. Mice were challenged with consecutive 10 days of OVA via conjunctival sac after systemic challenge with OVA and cholera toxin in alum. Several indicators for allergy were comparatively evaluated in wild-type and CCR6 KO EAC mice. Wild-type mice challenged with OVA via conjunctival sac following systemic challenge with OVA in alum had severe allergic conjunctivitis. The absence of CCR6 suppressed IgE secretion and allergic conjunctival inflammation. Reduced allergic inflammation was ascribable to reduced cytokine responses from Th-2 type in draining lymph node although Th17, regulatory T cells and dendritic cell subsets are not affected by the absence of CCR6. In addition, neutralization of CCR6 ligand, CCL20 could repress allergic conjunctival inflammation. Our findings suggested that CCR6 might be crucial for optimal development of Th2 immune responses and further allergic conjunctival inflammation in EAC model.