title: Influence of an n-3 long-chain polyunsaturated fatty acid-enriched diet on experimentally induced synovitis in horses.
abstract: Dietary n-3 long-chain polyunsaturated fatty acid (LCPUFA) supplementation has previously been shown to modify joint-related inflammation in several species, although information in the horse is lacking. We investigated whether dietary supplementation with n-3 LCPUFA would modify experimentally induced synovitis in horses. Twelve, skeletally mature, non-pregnant mares were randomly assigned to either a control diet (CONT) or an n-3 long-chain fatty acid-enriched treatment diet (N3FA) containing 40 g/day of n-3 LCPUFA for 91 days. Blood samples taken on days 0, 30, 60 and 90, and synovial fluid collected on days 0 and 90 were processed for lipid composition. On day 91, joint inflammation was stimulated using an intra-articular (IA) injection of 100 ng of recombinant equine IL-1beta (reIL-1β). Synovial fluid samples taken at post-injection hours (PIH) 0, 4, 8 and 24 were analysed for prostaglandin E2 (PGE2 ), matrix metalloproteinase (MMP) activity and routine cytology. Synovium and articular cartilage samples collected at PIH 8 were analysed for gene expression of MMP 1 and MMP 13, interleukin-1beta (IL-1β), cyclooxygenase 2 (COX-2), tumour necrosis factor-alpha and the aggrecanases, a disintegrin and metalloprotease with thrombospondin motifs (ADAMTS)-4 and ADAMTS-5. A 90-day feeding period of n-3 LCPUFA increased serum phospholipid and synovial fluid lipid compositions of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) compared to CONT horses. The reIL-1β injection caused an inflammatory response; however, there was no effect of dietary treatment on synovial fluid PGE2 content and MMP activity. Synovial tissue collected from N3FA horses exhibited lower expression of ADAMTS-4 compared to CONT horses. Despite the presence of EPA and DHA in the synovial fluid of N3FA horses, dietary n-3 LCPUFA supplementation did not modify synovial fluid biomarkers compared to CONT horses; however, the lower ADAMTS-4 mRNA expression in N3FA synovium warrants further investigation of n-3 LCPUFA as a joint therapy.
authors.affiliation: Department of Animal Science, Colorado State University, Fort Collins, CO, USA.
authors.forename: T N
authors.initials: TN
authors.lastname: Ross-Jones
authors.affiliation: Gail Holmes Equine Orthopaedic Research Center, Department of Clinical Sciences, Colorado State University, Fort Collins, CO, USA.
authors.forename: C W
authors.initials: CW
authors.lastname: McIlwraith
authors.affiliation: Gail Holmes Equine Orthopaedic Research Center, Department of Clinical Sciences, Colorado State University, Fort Collins, CO, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Kisiday
authors.affiliation: Department of Animal Science, Colorado State University, Fort Collins, CO, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Hess
authors.affiliation: Department of Animal Science, Colorado State University, Fort Collins, CO, USA.
authors.forename: D K
authors.initials: DK
authors.lastname: Hansen
authors.affiliation: Department of Animal Science, Colorado State University, Fort Collins, CO, USA.|Gail Holmes Equine Orthopaedic Research Center, Department of Clinical Sciences, Colorado State University, Fort Collins, CO, USA.
authors.forename: J
authors.initials: J
authors.lastname: Black
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary*; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006734:Horse Diseases / Q000139:chemically induced* / Q000178:diet therapy; D006736:Horses; D053583:Interleukin-1beta / Q000008:administration & dosage / Q000633:toxicity; D011994:Recombinant Proteins; D013585:Synovitis / Q000139:chemically induced / Q000178:diet therapy / Q000662:veterinary*
chemical_list: D015525:Fatty Acids, Omega-3; D053583:Interleukin-1beta; D011994:Recombinant Proteins
keywords: dietary; docosahexaenoic acid; eicosapentaenoic acid; equine; joint inflammation