PSXV-17 - Dietary postbiotic mediates cytokine gene expression in senior horses

Senior horses often exhibit chronic inflammation and decreased immune responses. Dietary Saccharomyces cerevisiae fermentation product (SCFP; Diamond V, Cedar Rapids, IA) has been shown to affect immune responses in several species. This study aimed to evaluate SCFP-mediated immune function in senior horses. Sixteen horses (24.8 ± 3.0 y; BW = 545.8 ± 61.9 kg) were allotted to two treatments: CON (n = 8; no SCFP supplementation) and SCFP top dressed onto a common concentrate for 56 d (21 g/d; n = 8). Body condition score (BCS), BW, whole blood cytokine (INF-ɣ, TNF-α, IL-1β, IL-6, IL-10, IL-4, IL-8, IL-13, IL-17) and COX-1 and COX-2 gene expression were measured at d 0, 42, 49 and 56. Horses were challenged with a monovalent influenza vaccine at d 42 (MIV; Fluvacc Innovator; Zoetis Animal Health, Parsippany, NJ). Pre-MIV (d 0-42) and post-MIV (d 42-56) responses were analyzed using general mixed model procedures. Pre-MIV, BW tended to increase (P = 0.09) over time. Expression of IL-10 tended to be lower for SCFP than CON (P = 0.09) and IL-13 expression decreased over time (P < 0.05). Post-MIV, BCS linearly increased over time (P = 0.006) while TNF-α tended to increase at d 49 and return to d 42 levels by d 56 (P = 0.06). Both INF-ɣ and IL-10 expression were lower for SCFP vs CON (P < 0.05). Gene expression of COX-2 tended to decrease (P = 0.06) at d 49 and return to the d 42 baseline by d 56. Gene expression of IL-13 tended to decrease with SCFP but increased with CON at d 49 with both returning to d 42 levels by d 56 (P = 0.08). Influenza H1 titers increased over time post-vaccination (P < 0.001) with no difference between treatments. Dietary SCFP may modulate pro-inflammatory and anti-inflammatory cytokine gene expression in senior horses.