Final Report Summary - STOPP VEHICLES (Specific Targeting of Organelles using Peptide-Polymer Vehicles)
Controlling the intracellular uptake of macromolecular therapeutics is of great interest for the development of novel drug delivery carriers. Favouring internalization via caveolae-mediated endocytosis, for example, would allow by-passing of the degradative pathway and increased delivery of the cargo in the endoplasmic reticulum (ER) and Golgi apparatus (GA) of cells. One strategy would be to mimic the activity of bacterial toxins derived from Escherichia coli (ET) and cholera toxin (CT) which, upon binding to ganglioside GM1 receptors found on the cell surface, internalize via caveolae-mediated endocytosis and travel to the ER of cells via the retrograde pathway. A number of small peptide sequences that binds to these GM1 receptors has already been identified.
Unfortunately, no in-depth study of the intracellular uptake and trafficking of these sequences has been carried out so far. In this study, three of the most promising GM1-binding sequences from the literature: VWRLLAPPFSNRLLP, NPPSPLSVSHRT, and HLNILSTLWKYR were synthetized, modified with a cysteine for ease of functionalization, and systematically studied for their cytotoxicity, affinity towards GM1 receptors, uptake pathway and intracellular trafficking. Results showed that these peptides were internalized mostly via a combination of clathrin-mediated endocytosis and macropinocytosis, leading to their accumulation in the lysosomes of cells. The potential of these peptides to be used as drug delivery carrier was also investigated using an assay based on the cross-presentation of a model antigen to dendritic cells. Whereas no significant enhancement of the antigen presentation was observed, useful conclusions could be drawn regarding the use of GM1-binding moieties for antigen delivery purposes. This discovery is of great importance for the future development of novel antigen carrier and will need to be taken into account in the wider effort to develop novel forms of vaccination worldwide.
Unfortunately, no in-depth study of the intracellular uptake and trafficking of these sequences has been carried out so far. In this study, three of the most promising GM1-binding sequences from the literature: VWRLLAPPFSNRLLP, NPPSPLSVSHRT, and HLNILSTLWKYR were synthetized, modified with a cysteine for ease of functionalization, and systematically studied for their cytotoxicity, affinity towards GM1 receptors, uptake pathway and intracellular trafficking. Results showed that these peptides were internalized mostly via a combination of clathrin-mediated endocytosis and macropinocytosis, leading to their accumulation in the lysosomes of cells. The potential of these peptides to be used as drug delivery carrier was also investigated using an assay based on the cross-presentation of a model antigen to dendritic cells. Whereas no significant enhancement of the antigen presentation was observed, useful conclusions could be drawn regarding the use of GM1-binding moieties for antigen delivery purposes. This discovery is of great importance for the future development of novel antigen carrier and will need to be taken into account in the wider effort to develop novel forms of vaccination worldwide.