抄録
When mouse macrophages were incubated with oxidized LDL (Ox-LDL) together with discoidal complexes of apolipoprotein A-I and dimyristoyl-phosphatidylcholine (DMPC/apoA-I), cholesteryl ester (CE) accumulation was strongly inhibited. Endocytic degradation of Ox-LDL by macrophages was completely inhibited by the presence of DMPC/apoA-I, indicaing interaction of DMPC/apoA-I with Ox-LDL might occur in the medium. To characterize the interaction of DMPC/apoA-I with Ox-LDL, Ox-LDL was incubated with DMPC/apoA-I in a cell-free system and re-isolated on Sephacryl S-400 gel filtration chromatography. Physico-chemical analysis of re-isolated Ox-LDL showed a 2-fold increase in phospholipids and a 10% increase in the protein moiety. The electrophoretic mobility of re-isolated Ox-LDL was significantly reduced as compared with control Ox-LDL. Cellular degradation of re-isolated Ox-LDL was reduced by<70%, suggesting a significant reduction in its ligand activity for the scavenger receptor. Incubation of Ox-LDL with free apoA-I led to apo-A incorporation into Ox-LDL, however, it did not alter the ligand activity. Thus, it was concluded that transfer of DMPC from DMPC/apoA-I to Ox-LDL induced altered recognition by the scavenger receptor. Because discoidal HDL particles similar to DMPC/apoA-I virtually are known to exist in the interstitial fluid, we propose here a neutalizing effect of discoidal HDL on Ox-LDL being a new mechanism for anti-atherogenic function of HDL in vivo.
