Lipid vector for the delivery of peptides towards intracellular pharmacological targets

The ability of single-chain lipopeptides to gain access to cellular compartments other than those related to degradation/recycling was first deduced from their capacity to deliver peptide antigens into MHC-class I loading mechanisms. The ability of lipopeptides to escape complete endosome degradation was further illustrated by the selective inhibition of different protein kinase C isoenzymes and, more recently, the presentation of agonistic activity towards the interferon gamma receptor. Taken together, several independent results indicate that modification of a peptide by a single lipid chain confers upon it intracellular trafficking properties that can be used to deliver functional cargo peptides into living cells; the endoplasmic reticulum, cytosolic protease activity, sites of kinase activity, or even the signalling pathway associated with cytokine stimulation, all appear accessible to peptide modified by a single lipidic moiety. In this context, the interferon gamma receptor can be considered as a very discriminative pharmacological model, useful for the comparative evaluation of the cellular delivery of lipopeptides, as it allows the unambiguous tracking of their intact delivery into a wide range of cellular compartments. This model is now being used to probe the influence of the nature of the lipid moiety on the trafficking properties of lipopeptides.