Characterization of cytokines associated with Th17 cells in the eyes of horses with recurrent uveitis.

The research study explores the role of Th17 immune cells in equine recurrent uveitis (ERU), a disease causing blindness in horses. The findings suggest these cells and their associated cytokines may be involved in ERU’s development, suggesting potential for horses with ERU to function as models for studying autoimmune uveitis.

Objective and methods of the study

• The research aims to understand the part Th17 cells, known to drive auto-immune inflammation in mouse models, play in recurring uveitis in horses.
• The researchers used banked, Davidson’s-fixed equine globes diagnosed histopathologically to have ERU and compared them via immunohistochemical analysis with healthy globes.
• Cytokines associated with Th17 cells such as IL-6, IL-17, and IL-23 were targeted for immunohistochemical staining, along with T-cell (CD3) and B-cell (CD79α) markers.
• Immunoreactivity specificity was established using the western blot analysis method.

Results of the study

• The nonpigmented ciliary epithelial cells and inflammatory mononuclear cells infiltrating the iris and ciliary body of ERU horses displayed positive staining for IL-6, IL-17, and IL-23, but the control group did not show this pattern.
• ERU-affected eyes had T-cell (CD3) positivity and did not have B-cell (CD79α) activity.
• All ERU and control globes had negative staining for Leptospira.

Conclusions and implications of the study

• The researchers observed strong immunoreactivity for IL-6, IL-17, IL-23, which along with the predominance of T lymphocytes as the inflammatory cells in ERU, suggests the role of IL-17-secreting helper T-cells in the pathogenesis of ERU.
• The findings suggest horses with ERU could serve as natural models for studying autoimmune uveitis, thus expanding potential research into this area of study.