The Ocular Surface Plays an Antigenic Role in the Initiation of a Mouse Model of Dry Eye Disease

Abstract

Purpose: : To determine if immunization with conjunctival or corneal epithelial cell suspensions from mice exposed to a dry, desiccating environment will induce pathogenic CD4⁺ T cells that can produce dry eye disease when adoptively transferred to athymic mice.

Methods: : C57BL/6 wild type (WT) female mice were exposed to a desiccating environmental stress (DS; subcutaneous scopolamine injections (0.5 mg/0.2 ml) TID, humidity <40%, and air flow by fans across wire meshed screened cages) for 10 days. Anti-CD25 antibody treated C57BL/6 WT mice were immunized by hind footpad injection in the presence of CFA with control or DS conjunctiva (1 X 10⁶) or cornea (7 X 10⁵) epithelial cells. After 5 days, 5 X 10⁶ spleen and cervical lymph node CD4⁺ T cells from immunized mice were injected IP into syngeneic T-cell deficient athymic recipients kept under non-stressed conditions. Recipient mice were sacrificed four days later and tissues were collected. Immunized and recipient tears were collected for detection of inflammatory cytokines using Luminex technology.

Results: : The immunized mice had a minimal response as evaluated by tear production, histology, and tear cytokine levels. However, CD4⁺ cells from mice immunized with DS cornea epithelial cells had a statistically significant increase in IL-12, IL-1β and TNF-α tear levels as compared to mice receiving the control cornea CD4⁺ cells. A statistically significant (*P=0.025) cellular infiltration into conjunctiva of recipient mice receiving CD4⁺ cells from mice immunized with DS conjunctiva epithelial cells was detected. There was significant cellular infiltration of both mononuclear cells (*P=0.014) and neutrophils (*P=0.001) into the conjunctiva of athymic recipient mice receiving CD4⁺ T cells from immunized mice that were injected with DS cornea cells. Adoptive transfer of CD4⁺ cells from immunized mice receiving control conjunctiva or cornea epithelial cells did not induce high cytokine tear levels in recipient mice.

Conclusions: : The results from the athymic recipient mice confirm that DS conjunctiva and cornea epithelial cells contain an antigenic determinant which is capable of generating pathogenic CD4⁺ T cells. Conjunctival and corneal epithelial cells exposed to a dry, desiccating environment have the capacity to initiate a CD4⁺ mediated immune response that is transferable.

Keywords: cornea: tears/tear film/dry eye • inflammation • cornea: epithelium