Novel cationic liposome formulation for the delivery of an oligonucleotide decoy to NF-κB into activated macrophages

Nuclear factor-κB (NF-κB) is involved in several pathological processes, such as inflammation. Pro-inflammatory genes expression can be down-regulated by using an oligonucleotide (ODN) decoy to NF-κB. Cationic liposomes are largely used to improve ODN uptake into cells, although a higher transfection efficiency and a lower toxicity are required to use them in therapy. In this work, we investigated the potential of a novel liposome formulation, based on the recently synthesised cationic lipid (2,3-didodecyloxypropyl) (2-hydroxyethyl) dimethylammonium bromide (DE), as the delivery system for a double stranded ODN decoy to NF-κB. Liposomes composed of DE or DE mixed with 1,2-dioleyl-sn-glycero-3-phosphoethanolamine or cholesterol as helper lipids were complexed with ODN at different +/- charge ratios. In vitro uptake and the effect of ODN, naked or complexed with DE-containing liposomes, were evaluated in lipopolysaccharide-stimulated RAW 264.7 macrophages. The use of helper lipids increased liposome physical stability up to 1 year at 4 °C. ODN complexed with DE/cholesterol liposomes, at the +/- charge ratio of 8, showed a limited cytotoxicity and the highest inhibition of nitrite production, inducible nitric oxide synthase protein expression and NF-κB/DNA binding activity. Confocal microscopy confirmed a high ODN cell uptake obtained with DE/cholesterol liposomes at the highest +/- charge ratio.