Influence of an n‐3 long‐chain polyunsaturated fatty acid‐enriched diet on experimentally induced synovitis in horses |
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| Authors: | T N Ross‐Jones C W McIlwraith J D Kisiday T M Hess D K Hansen J Black |
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| Institution: | 1. Department of Animal Science, Colorado State University, Fort Collins, CO, USA;2. Gail Holmes Equine Orthopaedic Research Center, Department of Clinical Sciences, Colorado State University, Fort Collins, CO, USA |
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| 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. |
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| Keywords: | joint inflammation equine dietary eicosapentaenoic acid docosahexaenoic acid |
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