Lysophosphatidylcholine Containing Docosahexaenoic Acid at the sn-1 Position is Anti-inflammatory

Lysophosphatidylcholine is known to be a lipid mediator in various cellular responses. In this study, we examined the anti-inflammatory actions of lysophosphatidylcholine containing docosahexaenoic acid esterified at the sn-1 position. First, in RAW 264.7 cells, DHA-lysoPtdCho suppressed the LPS-induced formation of NO concentration-dependently. However, ARA-lysoPtdCho showed a partial suppression, and LNA-lysoPtdCho had no significant effect. Additionally, DHA-lysoPtdCho also reduced the level of TNF-alpha or IL-6, but not PGE(2). In animal experiments, the i.v. administration of ARA-lysoPtdCho (150 or 500 mu g/kg) prevented zymosan A-induced plasma leakage remarkably with a maximal efficacy (Emax) of 50%, in contrast to no effect with LNA-lysoPtdCho. Remarkably, DHA-lysoPtdCho suppressed zymosan A-induced plasma leakage with an ED50 value of 46 mu g/kg and an Emax value of around 95%. Additionally, mechanistic studies indicated that the anti-inflammatory action of DHA-lysoPtdCho was partially related to the reduced formation of LTC4, TNF-alpha, and IL-6. When the interval time between lysoPtdCho administration and zymosan A challenge was extended up to 2 h, such a suppressive action of DHA-lysoPtdCho was augmented, suggesting that a DHA-lysoPtdCho metabolite is important for anti-inflammatory action. In support of this, 17-HPDHA-lysoPtdCho showed a greater anti-inflammatory action than DHA-lysoPtdCho. Furthermore, a similar anti-inflammatory action was also observed with i.p. administration of DHA-lysoPtdCho or a 17(S)-hydroperoxy derivative. Additionally, oral administration of DHA-lysoPtdCho also expressed a significant anti-inflammatory action. Taken together, it is proposed that DHA-lysoPtdCho and its metabolites may be anti-inflammatory lipids in vivo systems.