LAUSR

BACKGROUND Autologous conditioned serum (ACS) is a commonly administered intra-articular treatment for the management of osteoarthritis in athletic horses. OBJECTIVES To investigate the influence of exercise on the concentration of cytokines in a non-commercial method of ACS production. STUDY DESIGN Non-randomised cross over design. METHODS Whole blood was obtained from 8 healthy Standardbred horses immediately prior to, 1 hour and 24 hours following a single bout of exhaustive exercise. Blood was processed using a non-commercial method of ACS production. Fluorescent microsphere immunoassay (FMIA) analysis was performed to quantify Interleukin 1 receptor antagonist (IL-1Ra), Interleukin-10 (IL-10), Interleukin 1β (IL-1β) and tumour necrosis factor α (TNF-α) concentrations at each time point. Mixed effect repeated measures analysis of variance (ANOVA) was used to compare the pre-exercise and post-exercise cytokine concentrations. Significance was set at P < 0.05. RESULTS A reduced concentration of IL-1Ra (median 584.4, IQR 81.9 - 5098 pg/mL, P = 0.004) and an increased concentration of TNF-α (11.92, 9.28 - 39.75 pg/mL, P = 0.05) at 1 hour post-exercise was observed when compared to baseline values (IL-Ra 7349, 1272 - 10760 pg/mL; TNF TNF-α 11.16, 8.36 - 32.74 pg/mL). No difference in cytokine concentrations of IL-10 or IL-1β were found between any of the time points. MAIN LIMITATIONS The large biological variability and small sample size represents limitations of this study. CONCLUSIONS These results suggest that a single bout of intense exercise can reduce the concentration of the anti-inflammatory cytokine IL-1Ra and increase the concentration of the pro-inflammatory cytokine TNF-α, reducing the 'anti-inflammatory' cytokine composition of ACS. Our findings suggest that collection of blood for ACS production should be performed no sooner than 24 hours following a single episode of intense exercise.