Abstract

Synthetic high-density lipoprotein (sHDL) nanoparticles composed of apolipoprotein A-I (ApoA-I) mimetic peptide and phospholipids have been shown to reduce atherosclerosis in animal models. Cholesterol is mobilized from atheroma macrophages by sHDL into the blood compartment and delivered to the liver for elimination. Historically, sHDL drug discovery efforts were focused on optimizing peptide sequence for interaction with cholesterol cellular transporters rather than understanding how both sHDL components, peptide and lipid, influence its pharmacokinetics (PK) and pharmacodynamic (PD) profiles. We designed two sets of sHDL having either identical phospholipid but variable peptide sequences with different plasma stability, or identical peptide and phospholipids with variable fatty acid chain length and saturation. We found that sHDL prepared with proteolytically stable 22A-P peptide had 2-fold longer circulation half-time relative to the less stable 22A peptide. Yet, longer half-life did not translate into any improvement in cholesterol mobilization. In contrast, sHDL with variable phospholipid compositions showed significant differences in phospholipid PK, with distearoyl phosphatidylcholine-based sHDL demonstrating the longest half-life of 6.0 h relative to 1.0 h for palmitoyl-oleoyl phosphatidylcholine-based sHDL. This increase in half-life corresponded to a ~6.5-fold increase in the area under the curve for the mobilized cholesterol. Therefore, the phospholipid component in sHDL plays a major role in cholesterol mobilization in vivo and should not be overlooked in the design of future sHDL.