IL-17 Neutralization Mutes Inflammation in a Mouse Model of Experimental Autoimmune Lacrimal Keratoconjunctivitis

Abstract

Purpose: : To evaluate the effect of IL-17 neutralization on the immunopathogenesis of experimental autoimmune lacrimal keratoconjunctivitis (ALKC).

Methods: : Experimental ALKC was induced in female C57BL/6 wild-type (WT) mice exposed to desiccating stress (DS: subcutaneous scopolamine (0.5 mg/0.2ml) TID, humidity <40%, and sustained airflow from fans positioned on both sides of cages screened with wire mesh) for 10 days. Mice were also injected intraperitoneally with 500 µg of anti-IL-17 antibody or rat isotype control starting 3 days before exposure to DS and on days 1, 3 and 7 post-DS. On day 10, mice were sacrificed and tears were collected for cytokine analysis. CD4⁺ T cells were also isolated from the spleen and superficial cervical lymph nodes of mice exposed to 10 days of DS in the presence and absence of anti-IL-17 antibody or rat isotype control and adoptively transferred to syngeneic T cell-deficient nude recipient mice that were not administered anti-IL-17 antibody. On day 3 post-adoptive transfer, tears and ocular surface tissues were collected from nude recipient mice for analysis of cytokine levels and histopathology.

Results: : WT C57BL/6 mice exposed to DS for 10 days displayed significantly elevated tear (p=0.042) and serum (p=0.0001) levels of IL-17 compared to control mice. In contrast, mice treated with anti-IL-17 (days -3, 1, 3, and 7) showed muted tear cytokine levels of IL-17 (p=0.03) and TNF- (p=0.03) relative to mice that received isotype control antibody. Adoptive transfer of CD4⁺ T cells from DS mice also yielded enhanced levels of IL-17 in tears (p=0.021); however, nude recipient’s of CD4⁺ T cells from anti-IL-17-treated donor mice showed low levels of IL-17 (p=0.048) and TNF- (p=0.023) in tears at 3-days post-transfer that were similar to baseline levels observed in nude control mice.

Conclusions: : These results indicate that IL-17 production is increased in mice with ALKC and can be perpetuated in nude recipient mice following adoptive transfer of DS-specific CD4⁺ T cells. Neutralizing IL-17 antibody decreased inflammation in mice exposed to desiccating stress suggesting that IL-17 is an important player in the immunopathogenesis of ALKC.

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