Effective targeting of DC-sign by α-fucosylamide functionalized gold nanoparticles

Dendritic Cells (DCs), the most potent antigenpresenting cells, play a critical role in the detection of invading pathogens, which are recognized also by multiple carbohydrate-specific receptors. Among them, DC-SIGN is one of the best characterized, with high-mannose and Lewis-type glycan specificity. In this study, we present a potent DC-SIGN targeting device developed using gold nanoparticles functionalized with \u3b1-fucosyl-\u3b2-alanyl amide. The nanoparticles bound to cellular DC-SIGN and induced internalization as effectively as similar particles coated with comparable amounts of LewisX oligosaccharide. They were found to be neutral toward dendritic cell maturation and IL-10 production, thus envisaging a possible use as targeted imaging tools and antigen delivery devices

Preparation and immunogenicity of gold glycol-nanoparticles as anti-pneumococcal vaccine model

Capsular polysaccharides (CPS) of encapsulated bacteria are critical determinants of bacterial virulence and have been used in the development of protective conjugate vaccines. Nanomaterials loaded with carbohydrate antigens are emerging as promising synthetic vaccine candidates, alternative to classic polysaccharide/protein conjugate vaccines. Repetitive antigen display, the ability to potentiate immune responses through enhanced antigen delivery to the immune system and the possibility to tune the loading of well-defined carbohydrates on different scaffolds are key factors supporting nanotechnology-based vaccines. Moreover, other structures can be incorporated onto the nanosystems as active mediators to increase vaccine efficacy. In this context, gold glyco-nanoparticles (GNPs) functionalized with the synthetic tetrasaccharide repeating unit of Streptococcus pneumoniae serotype 14 (Pn14PS), and the peptide fragment OVA323-339, serving as a T-helper epitope, have been demonstrated as able to elicit in vivo specific and functional IgG antibodies against native Pn14PS, thus promoting uptake and killing of bacteria Pn14.[1] Herein, we report the preparation and immunological evaluation of new GNPs containing two synthetic CPS fragments related to serotypes 19F and 14 of Streptococcus pneumoniae (Tri-19F and Tetra-14) simultaneously displayed on nanoparticle surface, together with the T-helper peptide fragment OVA323-339. We aimed to explore the effect of these GNPs, coated with different antigen patterns, on the immunological response in mice and whether this response is affected by the presence of both saccharide antigens from diverse bacterial serotypes loaded onto the same nanoparticle. The main goal of this study was to determine whether these GNPs could induce specific antibodies against CPSs of both pneumococcal serotypes 14 and 19F or to affect the immune activity of either of them. Mice immunization showed that the concomitant presence of Tri-19F and Tetra-14 on the same nanoparticle critically enhanced the titers of specific IgG antibodies towards type 14 polysaccharide compared to GNP exclusively displaying Tetra-14. We also found that the bi-antigenic GNPs induced anti-Pn14PS IgG antibodies titers of the same order of magnitude as the currently used PCV13 human vaccine

Gold nanoparticles as carriers of streptococcus pneumoniae carbohydrate antigens fully synthetic vaccines

In the last years, gold nanoparticles have been largely evaluated as multivalent systems bearing biomolecules, thanks to their peculiarities. In particular, gold nanoparticles functionalized with (oligo)saccharides (gold glyconanoparticles, GNPs) have been developed in order to mimic the natural presentation of the carbohydrate coating which is present at the cell or pathogen surface. They are non-cytotoxic, soluble in biological media and easy to prepare and purify. Recently, GNPs coated with the tetrasaccharide Gal(\u3b21-4)Glc(\u3b21-6)[Gal(\u3b21-4)]\u3b2GlcNAc repeating unit of Streptococcus pneumoniae (SP) 14 capsular polysaccharide, OVA323-339 peptide as T helper cell, and \u3b2-D-glucoside to assist water solubility, in different molar ratio, were developed as synthetic conjugate vaccine4. The GNP bearing SP14/Glc/OVAp in 45:50:5 ratio resulted in the most active, able to induce IgG antibodies against native polysaccharide of S. Pneumoniae serotype 14. According to this result, we decided to prepare different GNPs bearing an analogue of the trisaccharide repeating unit ManNAc(\u3b21-4)Glc(\u3b11-2)Rha(\u3b11-OPO3-\u2192) of the 19F serotype of S. pneumoniae, alone or together with the tetrasaccharide of serotype 14. The idea is to develop new multiantigenic systems displaying different carbohydrate antigens arranged on a single nanoparticle. To prepare these GNPs, we have first synthesized the analogue of the trisaccharide antigen and a \u3b2-D-glucoside suitably functionalized with a thiol-ending linker in order to load them on the gold surface. The GNPs obtained, have been characterized by Transmission Electron Microscopy (TEM), Ultraviolet-Visible (UV/Vis), Circular Dichroism (CD), and Nuclear Magnetic Resonance (NMR). They show an exceptionally small core and uniform dispersion. Also, they are well soluble and stable in water. All the GNPs herein reported will be tested in vivo in mice to evaluate their ability to induce specific IgG antibodies against native capsular polysaccharide of S. pneumoniae type 14 and 19F