Klk13 is a Putative Autoantigen During the Immunopathogenesis of Experimental Autoimmune Lacrimal Keratoconjunctivis

Abstract

Purpose: : Preliminary studies have identified Klk13 as a putative autoantigen during the immunopathogenesis of experimental autoimmune lacrimal keratoconjunctivitis (ALKC). To further evaluate the role of Klk13 during ALKC we assessed i) the capacity of CD4⁺ T cells from Klk13-immunized mice to respond to ocular surface antigens present in cornea and conjunctiva of ALKC mice and ii) the ability of Klk13 to exacerbate ALKC in vivo.

Methods: : A co-culture experiment was performed to determine if immunization with Klk13 potentiates the proliferative response of CD4⁺ T cells from ALKC mice. CD4⁺ T cells were isolated from the spleen and cervical lymph nodes of Klk13-immunized (10µg) female C57BL/6 mice exposed to desiccating stress (DS; subcutaneous scopolamine injections (0.5 mg/0.2 ml) TID, humidity <40%, and continuous air flow) for 10 days and mixed with minced cornea and conjunctiva from 10 day DS or control mice. Cells were co-cultured for 4 days and T cell proliferation was measured by WST assay. To further determine if Klk13 contributes to the immunopathogenesis of ALKC mice were exposed to DS for 10 days and topically challenged with Klk13 (1.5ug/eye on days 7, 8 and 9). On day 10, tear cytokine levels, inflammatory cell infiltration and goblet cell density were evaluated.

Results: : CD4⁺ T cells isolated from Klk13-immunized mice in the presence of DS showed a significantly greater proliferative response to DS surface antigens compared to CD4⁺ T cells from mice exposed to DS alone. Topical challenge with Klk13 without DS was also sufficient to significantly enhance the CD4⁺ T cell proliferative response to ocular surface antigens in vitro. In addition, DS mice that were topically challenged with Klk13 displayed a marked increase in inflammatory cell infiltration into the conjunctiva that was associated with a significant (50%; p<0.001) decrease in goblet cell density relative to control mice or those exposed to DS alone.

Conclusions: : Taken together these data demonstrate that Klk13 potentiates the CD4⁺ T cell proliferative response to DS antigens and exacerbates the severity of ALKC. These results implicate Klk13 as a putative autoantigen during the immunopathogenesis of experimental ALKC.

Keywords: cornea: tears/tear film/dry eye • cytokines/chemokines • conjunctiva