A mouse model of allergic conjunctivitis permitting tear eosinophil quantification

Introduction: Allergic conjunctivitis is an immune-mediated inflammatory disease of the conjunctiva that is induced by antigens. Allergic conjunctivitis can cause various symptoms such as ocular itching, hyperemia and edema. Developing experimental animal models that show clinical symptoms and methods for quantitative and objective evaluation is important for understanding allergic conjunctivitis. Therefore, this study aimed to develop an ovalbumin (OVA)-induced mouse model of allergic conjunctivitis and a useful method for evaluating symptoms of allergic conjunctivitis. Methods: ICR mice were sensitized by an intraperitoneal injection of OVA in PBS containing alum on days 0 and 5. Subsequently, local sensitization was then performed once daily from days 14 to 28, by instilling OVA in PBS into the both eyes. Drug treatment was administered once daily from days 14 to 28. Mice were randomly assigned topical treatment groups: Group 1, 0.1% betamethasone; Group 2, 0.025% levocabastine; Group 3 PBS (control). Results: Mice showed marked eye scratching behavior, hyperemia, edema, infiltration of eosinophils into tears and increased antigen-specific immunoglobulin E antibody levels in tears and the serum. These symptoms were inhibited by instillation of levocabastine and betamethasone, which are used clinically for the treatment of allergic conjunctivitis. Discussion: This method may be useful for evaluation of the symptoms of allergic conjunctivitis in experimental and clinical settings. In particular, the developed method, which measures the number of eosinophils in tears collected with phenol red threads, may enable the quantitative, objective, and noninvasive evaluation of the severity of allergic conjunctivitis.