Abstract 682: Incorporation Of Phosphatidylserine Enhanced Anti-inflammatory Effects Of Synthetic High Density Lipoproteins

Objective: Phosphatidylserine (PS) is an anionic, bioactive phospholipid component in endogenous high-density lipoprotein (HDL). The PS content in HDL has been found to be positively correlated with various HDL functions including cholesterol efflux and anti-inflammation effects. It has been hypothesized that introducing PS to synthetic HDL (sHDLs) could enhance the therapeutic effects of sHDLs. To test this hypothesis, the effects of PS on particle characteristics, anti-inflammatory effects, in vitro and in vivo cholesterol efflux capacities, and pharmacokinetic profiles of sHDLs were investigated in the present study. Methods: sHDLs composed of ApoA-1 mimetic peptide 22A, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine (POPS) were prepared using the lyophilization-rehydration method. The anti-inflammatory effects of different sHDLs were investigated on LPS-treated RAW 264.7 macrophages and HUVEC cells. The in vitro cholesterol efflux effects of sHDLs were evaluated on [ 3 H] cholesterol-laden J774 cells. For in vivo studies, sHDLs containing different POPS contents were injected into Sprague-Dawley rats through the tail vein. The serum concentrations of phospholipids, total cholesterol, and free cholesterol at different time points were quantified. Results: sHDL with different PS contents presented similar particle sizes, while sHDLs containing higher PS contents showed greater particle stability. No statistical difference in in vitro cholesterol efflux capacity was observed among sHDLs with different PS contents. On LPS-treated macrophages and endothelial cells, PS-containing sHDLs inhibited the production of pro-inflammatory cytokines to a greater extent compared to PC-sHDLs. PS-containing sHDLs showed slightly higher cholesterol mobilization effects at early time points in vivo . However, no difference was found in the pharmacokinetic profiles between different sHDLs. Conclusions: Incorporating anionic phosphatidylserine into sHDL particles significantly increased their anti-inflammatory effects while not greatly affecting the cholesterol efflux capacity and pharmacokinetic profiles of sHDLs.