Transconjunctival immunotherapy using cholera toxin B to treat experimental allergic conjunctivitis in a mouse model

Abstract

We evaluated the use of immunological biomarkers in transconjunctival immunotherapy by using cholera toxin B for treating experimental allergic conjunctivitis in a mouse model. Balb/c mice were sensitized using intraperitoneal injections of ovalbumin (OVA) and were then divided into two groups. The first group was treated by topical instillation of OVA after the instillation of combined OVA and cholera toxin B (CTB) solution B group). The second group was treated by topical instillation of OVA alone (allergy group). The control group consisted of nonsensitized mice undergoing topical OVA instillation only. The numbers of eosinophils and CD4-positive lymphocytes in the conjunctiva were determined histologically, and the observation of immunoglobulin A (IgA)-positive cells in the conjunctiva was performed by immunohistochemistry. Cytokine concentration in the conjunctiva was determined by the protein-array methods. Messenger RNA expression of T-cell-specific markers, such as T-bet, GATA-3, and Foxp3, in the conjunctiva was detected by reversed transcriptase polymerase chain reaction. The number of eosinophils and CD4-positive lymphocytes increased significantly in the allergy group compared with the control group (P<0.001) but showed no difference between the CTB group and control group. Concentrations of interleukin 4 (IL-4) (P<0.05), B-lymphocyte chemoattractant (P<0.01), and thymus-expressed chemokine (P<0.05) in the conjunctiva were significantly higher in the CTB group than in the other two groups. GATA-3 messenger RNA (mRNA) in the conjunctiva was expressed in the three groups, but T-bet and Foxp3 were not detected. Transconjunctival immunotherapy using CTB can be evaluated by histological examination of eosinophils and CD4-positive T cells, and a mucosal immunity-associated chemokine and a helper T-cell-17-associated chemokine as biomarkers.