Abstract
Purpose::
Chronic equine recurrent uveitis (ERU) is a common cause of blindness in horses. ERU is thought to be an immune-mediated disease and likely has multiple pathogeneses. Several human clinical uveitis syndromes, such as Behcet's disease, have been recently characterized by their aqueous humor (AH) and serum cytokine profiles. To further characterize ERU and to help differentiate clinical syndromes, serum and AH inflammatory cytokine profiles were analyzed in horses with ERU and with other ocular disease (OOD).
Methods::
Serum was collected from normal horses (n=6), horses with chronic ERU (n=21), and horses with other ocular disease (glaucoma, n=1; trauma, n=1; cataract, n=2; and inflammatory corneal disease, n=7). AH was collected from 7 horses with chronic ERU and 7 normal horses. Cytokine profiles were performed using the RayBio Human Cytokine Antibody array that detects 42 inflammatory cytokines. Cytokine arrays were read using a Lumi-Imager chemiluminescence imager.
Results::
Serum leptin was detected in significantly higher numbers of horses with ERU (80.1%) and in horses with OOD (54.6%), compared to normal horses (33.3%)(contingency analysis; P=0.02). Other cytokines that were detected more frequently in the serum of horses with ERU and OOD compared to normal horses include tumor necrosis factor B (ERU 19%; OOD 36%) and platelet-derived growth factor B (ERU 14.3%; OOD 54.6%). VEGF and RANTES were detected in AH of a significantly higher number of horses with ERU (VEGF=100%; RANTES=86%) than in AH of normal horses (VEGF=40%; RANTES=40%; P=0.04). There were no significant differences in cytokine profiles between Appaloosa horses (n=10) with ERU and other breeds with ERU (n=11).
Conclusions::
This human cytokine array has yet to be validated for equine cytokines; however, this preliminary study demonstrated that a high number of horses with inflammatory ocular disease were positive for serum leptin. Further study is warranted to determine the role of leptin in the pathogenesis of uveitis. Although clinical syndromes could not be differentiated with these limit number of samples, this study suggests that RANTES and VEGF may be considered as therapeutic targets for uveitis and further study is needed.
Keywords: cytokines/chemokines • uveitis-clinical/animal model • autoimmune disease