Effect of a dietary nutraceutical "STRUCTURE-Joint" on response of horses to intra-articular challenge with IL-1: implications for tissue adaptation to stress.

The purpose was to determine local (articular) and systemic effects of intra-articular interleukin-1 in horses supplemented with a dietary PUFA supplement [STRUCTURE-Joint (ST-J)]. Sixteen (16) healthy, mature, light breed horses were randomly assigned to diets containing 0 or 120 mL (n = 8 per group) of ST-J for 30 d. On days 0 (prior to beginning supplementation) and 27, recombinant equine interleukin-1β (reIL-1 β) (75 ng) was injected into the left or right intercarpal joint to induce mild, transient synovitis. Synovial fluid was obtained by aseptic arthrocentesis at postinjection hour 0 (immediately prior to IL-1 injection), 6, 12, and 72. ST-J supplementation for 30 d significantly increased synovial fluid nitric oxide, and resolvin D1 compared with the unsupplemented control group and significantly increased PGE2 levels and reduced joint circumference in the ST-J treated horses on day 30 compared to the same group of horses on day 0. There was also a significant increase in plasma hemoglobin, free and total bilirubin, and decrease in plasma glucose. These data provide evidence for the usefulness of ST-J to modulate physiological variables with importance in exercise performance and tissue adaptation to exercise stress and further research on this product is warranted.