Immunogenicity, Inflammation, and Lipid Accumulation in Cynomolgus Monkeys Infused with a Lipidated Tetranectin-ApoA-I Fusion Protein.

High density lipoprotein (HDL)-targeted therapies, which promote cholesterol efflux from cells, are currently in development for reducing cardiovascular events in acute coronary syndrome. Human apolipoprotein A-I (apoA-I), the major HDL protein, was fused to the trimerization domain of tetranectin (TN) and complexed with phospholipids to generate a HDL mimetic (lipidated TN-ApoA-I) with reduced renal clearance and enhanced efficacy. Cynomolgus monkeys received 24-h intravenous infusions of control, 100 mg/kg or 400 mg/kg lipidated TN-ApoA-I every 4 days for 3 weeks, followed by a 6-week recovery period. After multiple infusions of lipidated TN-ApoA-I, clinical condition deteriorated and was accompanied by changes indicative of a progressive inflammatory response; increased levels of cytokines, C-reactive protein and vascular/perivascular infiltrates in multiple tissues. Rapid formation of antidrug antibodies occurred in all animals receiving lipidated TN-ApoA-I. Enhanced drug clearance corresponding to a relative lack of high molecular weight immune complexes in blood, suggestive of preferred removal/clearance, was observed in some animals. Expected dose-dependent increases in serum lipids were accompanied by vacuolated monocytes/macrophages in multiple organs, which in the glomeruli were shown to be CD68-positive, contain lipid and co-localized with granular IgG deposits. Lipid accumulation may have been a direct result of a high drug load, possibly enhanced by immune complex formation, inflammation, and altered lipid metabolism. Noteworthy was the inter- individual inconsistency in the severity of clinical and histopathologic findings, drug clearance and inflammatory markers. In conclusion, multiple infusions of lipidated TN-ApoA-I resulted in high immunogenicity, lipid accumulation and were not well tolerated in nonhuman primates.

Recombinant high density lipoprotein nanoparticles for target-specific delivery of siRNA.

PURPOSE: Regulation of gene expression using small interfering RNA (siRNA) is a promising strategy for treatments of numerous diseases. However, the progress towards broad application of siRNA requires the development of safe and effective vectors that target to specific cells. In this study, we developed a novel recombinant high density lipoprotein (rHDL) vector with high siRNA encapsulation efficiency. METHODS: They were prepared by condensing siRNA with various commercial cationic polymers and coating the polyplex with a layer of lipids and apolipoprotein AI (apo AI). The rHDL nanoparticles were used to transfect SMMC-7721 hepatoma cells with stable luciferase expression. The uptake and intracellular trafficing of siRNA were also investigated. RESULTS: Characterization studies revealed these rHDL nanoparticles had similar physical properties as natural HDLs. The various rHDL formulations had high silencing efficiency (more than 70% knockdown) in hepatocytes with minimum cytotoxicity. Moreover, the uptake of rHDL by SMMC-7721 was confirmed to be mediated through the natural HDL uptake pathway. CONCLUSIONS: The work described here demonstrated the optimized rHDL nanoparticles may offer a promising tool for siRNA delivery to the liver.