Inflammatory Cytokine Gene Expression in Blood During the Development of Oligofructose-Induced Laminitis in Horses

Abstract

Systemic inflammation is a risk factor for laminitis in horses and precedes the onset of lameness in experimental models. We therefore hypothesized that whole-blood inflammatory cytokine expression would increase during the development of laminitis in a carbohydrate overload model. Blood samples were obtained from 14 horses undergoing laminitis induction with 10 g/kg oligofructose as part of another study. Samples were collected at 0, 8, 12, 16, 20, and 24 hours, and lameness evaluations were performed every 4 hours. Expression levels of interleukin-1β (IL-1β), IL-6, IL-8, IL-10, and tumor necrosis factor-α were measured in whole blood by using real-time PCR. IL-1β, IL-8, and IL-10 expression increased above baseline from 8 to 24 hours (P < .001), and IL-6 expression increased at 16 and 20 hours (P = .005). Expression of tumor necrosis factor-α did not change over time. All horses developed clinical laminitis between 12 and 24 hours. Increased mean IL-1β, IL-8, and IL-10 expression detected at 8 hours therefore preceded the onset of lameness. We conclude that peripheral leukocyte cytokine expression increases as systemic inflammation develops in an alimentary carbohydrate overload model of laminitis, and this precedes detection of lameness. Results support current recommendations to control the systemic inflammatory response in order to lower the risk of laminitis in horses.