IMPROVED LEISHMANICIDAL EFFECT OF PHOSPBOROTIOATE ANTISENSE OLIGONUCLEOTIDES BY LDL-MEDIATED DELIVERY

We have designed antisense oligonucleotides that can interact with lip oproteins in order to use them as vectors to facilitate the uptake by those cells expressing the corresponding receptor. Phosphorothioate (P S) oligonucleotides were linked at the 5' end to a palmityl group givi ng rise to PSPal conjugates. Such a modification enables the oligonucl eotide to form a stable non-covalent complex with low density lipoprot eins (LDL) through hydrophobic interactions. The antisense effect of L DL-oligonucleotide complexes was assayed by targeting the mini-exon se quence of Leishmania amazonensis in infected mouse peritoneal macropha ges. A 16-mer antisense PSPal oligonucleotide/LDL complex exerted a mo re pronounced sequence-specific effect than the free oligomer: about 2 5% and 10% of infected macrophages were cured by a 48 h incubation in the presence of 2.5 mu M of the complexed and the free oligomer, respe ctively. When oxidized LDL was used instead of the native one for comp lexation, a further 2-fold increase in the antisense effect was observ ed suggesting that alternative (unregulated) scavenger receptor can be used for more efficient delivery of antisense oligonucleotides into m acrophages. In addition, a significant reduction of the parasitic load was observed in those cells that were not fully cured.