The Role of Group 2 Innate lymphoid Cells (ILC2s) in Mouse Models of Papain-Induced Conjunctivitis.

Abstract

Purpose: Group 2 innate lymphoid cells (ILC2s) produce large amounts of Th2 cytokines in response to IL-33 and induce eosinophil infiltration. We previously identified ILC2s in mouse lacrimal glands and in conjunctivae in response to papain induced inflammation. To clarify the role of ILC2s in papain-induced conjunctivitis, ILC2s were depleted in mice models.

Methods: To make papain-induced conjunctivitis model mice, papain-soaked soft contact lens (2mm diameter) was inserted into the conjunctival sacs of C57/BL6 (B6)-Rag2^-/- mice. To deplete ILC2s, 200 μg of anti-CD25 antibody was injected into the Rag2^-/- mice two days before contact lens insertion. We also used B6-Rag2/common γ chain (cγ)^-/-, which lack acquired immune systems and ILC2s. 4 days after contact lens installation, the eyes were subjected to flow cytometry analysis or histological analysis. To identify mouse ILC2s by a flow cytometer, anti-mouse lineage mix antibodies, ST2, CD25, CD127 and CD90.1 antibodies were used to mouse conjunctival tissues from papain-induced conjunctivitis model.

Results: Anti-CD25 antibody injection in Rag2^-/- mice accomplished 93% depletion of ILC2s in the conjunctival tissue compared to PBS injection. The numbers of infiltrated eosinophil in papain-induced conjunctivitis models diminished by the anti-CD25 antibody treatment (48 ± 8 versus 14 ± 6.4, mean number of eosinophil ± SD per slides, n = 8, P< 0.05 by Mann-Whitney’s U test). ILC2 deficient Rag2/cγ^-/- mice also showed diminished numbers of eosinophil compared to Rag2^-/- mice (53 ± 20 versus 8 ± 4, n = 8 , P< 0.05)

Conclusions: ILC2s depletion by anti-CD25 antibody could diminish eosinophil infiltration in papain-induced conjunctivitis model.