Abstract
Purpose: :
Equine recurrent uveitis [ERU] is a spontaneous disease that is the most common cause of blindness in horses, affecting up to 15% of the horse population. Th17 cells have been shown to be the major cell population driving the pathogenesis in several mouse models of autoimmune inflammation, including experimental autoimmune uveitis. The purpose of this study is to investigate the role that a Th17 cell-mediated autoimmune response plays in the pathogenesis of ERU.
Methods: :
Banked, formalin fixed equine globes ERU (n=4) were compared immunohistochemically to normal control globes (n=4). Immunohistochemical staining using the horseradish peroxidase method, with DAB as the chromagen, was performed using a pan-Leptospira antibody, IL-17 (Santa Cruz Biotech., 1:100), and IL-23 (AnaSpec, 1:500,000). In addition, immunostaining for T- cell [CD3] and B-cell [CD79α,] markers was performed. Staining was recorded as positive or negative.
Results: :
Immunohistochemical staining was positive for IL-17and IL-23 in the iris, ciliary body, and choroid of the ERU horses [n=4], but negative in controls [n=4]. ERU-affected eyes were CD3 postive (n=3), and CD79α negative (n=4). Staining for Leptospira was negative in all ERU- normal globes.
Conclusions: :
Strong immunoreactivity for IL-17 and IL-23, in conjunction with the fact that T- lymphocytes are the predominating inflammatory cell present in ERU, suggests that IL-17 secreting helper-T cells play a role in the pathogenesis of ERU. These findings suggest that horses with ERU may serve as a spontaneous animal model for autoimmune uveitis.
Keywords: uveitis-clinical/animal model • autoimmune disease • immunohistochemistry