Mechanism Of Conjugated Linoleic Acid Modulating Inflammatory Reaction In Weaned Pigs

One animal feeding experiment and two in vitro experiments were conducted to investigate the effects of conjugated linoleic acid (CLA) on immunological stress. (1) To explore the effects of CLA on growth and immune response in weaned pigs, 72 weaned pigs at 28 ± 3 d of age were used in a 2×2 factorial design. The main factors consisted of diets (2% CLA or 2% soybean oil) and Immunological challenge (LPS or saline). On d 14 and d 21, half of pigs in each dietary treatment were injected intraperitoneally with either 100μg/kg BW LPS or an equivalent amount of sterile saline. Blood samples were collected at 2 h post-injection and plasma cortisol, prostaglandin E₂(PGE₂) and tumor necrosis factor-α (TNF-α) were determined. On d 21, the lymphocytes were collected and incubated with LPS to determine the expression of TNF-α mRNA. The results showed that CLA can alleviate the ADG (P < 0.05) decrease caused by LPS injection. On d 14 and d 21, dietary CLA prevented the production of TNF-α , cortisol and PGE₂ after LPS injection (P < 0.1). TNF-α mRNA was also inhibited in the blood peripheral lymphocytes (P < 0.05) . (2) In order to determine the mechanisms of two CLA isomers anti-immunological activity, peripheral blood lymphocytes of weaned pigs were cultured with media containing 40μmol/L of c9, t11-CLA, or t10, c12-CLA and two ω-3 fatty acid docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were used as control groups. c9, t11-CLA or tlO, C12-CLA can prevent the activation of nuclear factor-κB (NF-κB) (P < 0.1), as a result, the TNF-α mRNA expression was inhibited (P < 0.05) . (3) In order to investigate the effects of CLA isomers on peripheral blood lymphocyte function, peripheral blood lymphocytes of weaned pigs were cultured with media containing 40 umol/L of c9, t11-CLA or t10, c12-CLA and challenged with ConA or PHA. Lymphocyte proliferation, IL-2 and NO concentration in the supernatant were determined. c9, t11-CLA enhanced lymphocyte proliferation stimulated with ConA. There is no difference in IL-2 and NO production.