Is the antiatherosclerotic potency of HDL modulated by the origin of HDL

Abstract Different HDL preparations from rabbit blood were injected intravenously (10 mg HDL protein/injection and animal) into cholesterol fed rabbits twice a week for 8 weeks. The composition of the used high density lipoprotein (HDL) was modified by dietary pretreatment. HDL-1 was taken from rabbits after 8 weeks pellet diet, HDL-2 after 8 weeks fish-oil rich diet and HDL-3 after 8 weeks of cholesterol rich diet. The animals treated with HDL-1 and HDL-2 had a significantly smaller area of intima covered with fatty streaks than the control animals (injection of saline instead of HDL). The injection of HDL-3 was without influence. These differences were correlated with changes in the level of free and esterified cholesterol (FC and CE) in kidney, liver and aorta of the rabbits, but not with the level of cholesterol in the serum lipoproteins. We investigated simultaneously the influence of the different HDL preparations on the cholesterol content in rabbit skin fibroblasts (RSF), rabbit smooth muscle cells (SMC) and human hepatoma cell line Hep G2. Additionally the influence on the proliferation of SMC was studied. HDL-1 diminished the level of FC in cholesterol enriched RSF and rabbit SMC, whereas both other HDL preparations had no effect. The level of FC in Hep G2 was not influenced. HDL-1 and HDL-3 stimulated the proliferation of rabbit SMC, whereas HDL-2 had no such influence. The data support the antiatherosclerotic role of HDL injections in cholesterol fed rabbits, but the composition of the used HDL seems to modify this influence, probably by different effects on the biochemical changes induced by the HDL.