Influence of Fatty Acid Modification on Uptake of Lovastatin-Loaded Reconstituted High Density Lipoprotein by Foam Cells.

PURPOSE: Spherical reconstituted high density lipoprotein (rHDL) can target atherosclerotic lesions by the very low density lipoprotein (VLDL) receptor, which is seldom expressed in liver. By promoting this pathway, the targeting efficiency was hyphothesized to be improved due to avoiding undesired uptake in liver mediated by the scavenger receptor class B type I (SR-BI). In this study, how fatty acid modification in spherical rHDL influenced the VLDL receptor-mediated endocytosis pathway was investigated.

METHODS: Stearic acid (SA) and arachidonic acid (AA) with different saturation levels were utilized to modify the lovastatin-loaded rHDL (LS-rHDL). Phagocytosis test on foam cells with or without cholesteryl ester transfer protein (CETP) expression was conducted to observe the cellular uptake of the SA or AA modified rHDL and the non-modified one. Raman spectroscopy, guanidine hydrochloride (Gdn-HCl) denaturation experiment and in vitro evaluation of drug release were used to analyze the related mechanism.

RESULTS: In comparison with the non-modified rHDL, AA modification could reduce the packing order of the rHDL phospholipid acyl chains, leading to the decreased apoA-I binding extent with lipid and the increased drug release, while the opposite was true for SA modification. The AA-modified rHDL exhibited a higher uptake of foam cells expressing CETP than the non-modified one, while the SA-modified one showed the lowest cellular uptake among the three rHDLs.

CONCLUSIONS: Increased unsaturation level can facilitate lipid-interchange process where the cargo in rHDL core may transfer to VLDL more easily, and then promote the endocytosis mediated by the VLDL receptor.