Ponente
Descripción
Sticholysins I and II (StI/II, Sts), two pore-forming proteins produced by the sea anemone Stichodactyla helianthus, are non-cysteine proteins that show a preference for sphingomyelin-containing membranes. They are able to form oligomer pores of diameter 2 nm and to permeabilize model and biological membranes in nM range [1]. Beyond their functional activity, Sts co-encapsulated with an antigen into liposomes constitute an atractive vaccine platform to improve the antigen-specific cytotoxic T CD8+ lymphocytes response. This liposomal formulation induced an anti-tumor response which was strongly affected by CD8+ T cells depletion [2]. Interestingly, free-Sts were able of inducing activation of DCs in vitro and it was dependent of TLR-4 and MyD88, suggesting a decoupling of the immunomodulatory properties of Sts and their pore-forming ability [3]. Furthermore, novel non-viral gene delivery bio-responsive systems based on the StI mutant, StIW111C, to increase the endosomal release of a plasmid DNA (pDNA) has been explored. Reducible conjugates obtained by linking StIW111C to cationic or anionic peptides exhibited functional activity dependent of a reducing environment. Positive nanometric complexes comprised of the mix of the cationic conjugate with pDNA and a peptide excess showed higher heterogeneity than the binary mix of pDNA and peptide. Although the cationic polyplexes were efficiently internalized and able to permeabilize endosomes in vitro, the expression of the reporter gene was not observed. This could be explained by incomplete endosome destabilization due to limited number of pores formed in the endosomal membranes. Thus, complexes based on the anionic conjugate and cationic lipid nanoparticles is also being explored
