Dietary polyunsaturated fatty acids (PUFA) including arachidonic acid (AA), eicosapentaneioc acid (EPA), and docosahexaenoic acid (DHA) alter the production of inflammatory mediators. The objectives of this study were twofold: first, to examine the effects of EPA or DHA alone or in combination on the inflammatory response of stimulated cartilage explants from gilts; second to characterize the effects of dietary PUFA supplementation on bone, cartilage, and synovial fluid in sows and gilts. For the first objective, cartilage was obtained from the humeral-ulnar joints of Yorkshire x Landrace market sized gilts. Explants were harvested from the humeral-ulnar joints within 8 h of slaughter. Explants were allocated to culture plates and cultured in 1 mL of DMEM:F12 medium for 24 h with 10% fetal bovine serum. At 48 and 72 h, 1 mL of treatment media containing 15 ng/ml of recombinant porcine IL-1 was added to each well. At 48, 72, and 96 h after cartilage was allocated to wells, media were removed from each well and reserved for analyses. Media were analyzed for proteoglycan, nitric oxide (NO), interleukin-6 (IL6) and prostaglandin E2 (PGE2). In general, when EPA and/or DHA are supplemented to explants in combination with linoleic acid (LA) NO and PGE2 release is decreased. Explants treated with 25 μg/ml DHA released 53% less NO into the media than explants treated with the same concentration of EPA and 60% less than explants treated with LA alone. These data demonstrate that EPA and DHA are capable of modulating the inflammatory response in porcine articular cartilage in vitro. To complete the second objective sows and gilts were fed either a basal corn/soybean meal based diet (CON), or the basal diet supplemented with PUFA (Gromega 365; JBS United, Sheridan, IN). Sows completed an average of 5.5 parities while gilts reached an average BW of 111 kg at time of slaughter. Cartilage was biopsied from both humeral-ulnar joints of 14 sows (7/trt) and 16 gilts (8/trt) within 30 h of slaughter for fatty acid analysis and explant cultures. Synovial fluid was collected from the carpal joints of each pig post-mortem. The right fused radius/ulna were analyzed using computed tomography (CT). CT scans of the radius/ulna from gilts revealed no differences for cortical width and bone density. Sows fed PUFA had greater cortical width of the proximal ulna (P<0.05) and decreased cortical width of the distal radius (P<0.05). Sows fed PUFA had increased DHA (P<0.01), decreased C20:1 (P<0.01), and decreased omega-6 to omega-3 ratio (P<0.05) in cartilage. Gilts fed PUFA had increased EPA (P<0.10), DHA (P<0.01), C22:1 (P <0.01), and C22:5 (P<0.10) in cartilage. Although the PUFA diet increased omega-3 incorporation into chondrocytes, the biological significance is unclear since concentrations of AA were at least 9-fold higher than EPA or DHA. Bone density was not affected by a PUFA enriched diet. Thus, if omega-3 fatty acids can mitigate inflammation in joints, the benefit may be the result of systemic changes in inflammatory mediators.
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