Aged Mice Exhibit Severe Exacerbations of Dry Eye Disease with an Amplified Memory Th17 Cell Response

The prevalence as well as the severity of dry eye disease increase with age. Memory T helper 17 (Th17) cells (CD4⁺IL-17A⁺CD44⁺) drive the chronic and relapsing course of dry eye disease. Here, we investigated the contribution of memory Th17 cells to age-related dry eye disease, and evaluated memory Th17 cell depletion with anti-IL-15 antibody as a strategy to abrogate the severe exacerbations of dry eye disease observed in aged mice. After initial exposure to desiccating stress, aged mice maintained higher frequencies of memory Th17 cells in the draining lymph nodes relative to young mice. Upon secondary exposure to desiccating stress, aged mice developed more severe corneal epitheliopathy than young mice, which is associated with increased local frequencies of Th17 cells (CD4⁺IL-17A⁺). Treatment with anti-IL-15 antibody decreased the enlarged memory Th17 pool in aged mice to frequencies comparable with young mice. Furthermore, anti-IL-15-treated mice showed significantly reduced conjunctival infiltration of Th17 cells and lower corneal fluorescein staining scores compared with saline-treated control mice. Our data suggest that age-related increases in the memory Th17 compartment predispose aged mice toward the development of severe corneal epithelial disease after exposure to a dry environment. Selectively targeting memory Th17 cells may be a viable therapeutic approach in the treatment of age-related dry eye disease.