Traceable Iron Oxide Based Nanoparticles for Antigen/Adjuvant in vivo Delivery to Lymph Nodes

Most of the currently available vaccines are based on the inactivation of the pathogen, which is not a valid strategy for fighting several chronic infections and, especially, cancer.[1,2] Here we present PEGylated iron oxide... [ view full abstract ]

Most of the currently available vaccines are based on the inactivation of the pathogen, which is not a valid strategy for fighting several chronic infections and, especially, cancer.[1,2] Here we present PEGylated iron oxide based nanoparticles (IONPs) as traceable delivery system for directing tumour antigens and adjuvants to lymph nodes (LNs), leading to improved antitumor immunity and survival outcomes. The nanovehicles allow using lower doses of the immunostimulatory molecules to achieve a given response and thereby enhance their safety profiles. Moreover, other bioactive molecules and drugs can be co-delivered to further improve the efficacy and therapeutic index of the anticancer therapy.
We designed and created PEGylated IONP-filled micelles carrying short oligodeoxynucleotides with CpG motifs as adjuvants and ovalbumin (OVA) as antigen. Doping with rhodamine B-phospholipids[3] was used to monitor in vitro cell uptake, whilst chemistry-free radiolabeling with 67Ga could be applied to study the biodistribution in vivo by SPECT imaging. The immunostimulatory potential of the constructs was tested analyzing cytokine, antibody production and cellular mediated immunity. Immunization against tumour-antigen was performed to demonstrate the anti-tumour immunity.
We obtained water soluble micelles with a diameter below 100nm, which were internalized through the endocytic pathway and co-localized with the toll-like receptor 9 (TLR9). SPECT imaging showed accumulation of these constructs in the LNs and both in vitro and in vivo assays demonstrated enhanced immunostimulatory activity than with the free molecules. The analysis of adaptive immune response demonstrated the production of anti-OVA antibodies and the activation of antigen specific CD8+ T cells, able to significantly slow down the appearance of tumour.
The nanoconstructs were able to deliver the immunostimulatory molecules in the correct intracellular organelle, where the CpGs could reach TLR9 and, therefore, induce cytokine production in vitro. There was no systemic effect in vivo, concluding that the effect was directed to lymphoid organs. The CD8+ T cell subset was successfully activated against the antigen, crucial characteristic for generating anticancer immunity. The anti-tumour studies showed the potential of these systems for developing cancer vaccines.[4]
References
(1)Landrith,T.A. et al. Semin.Immunopathol.2015,37,261–270.
(2)Schreiber,R.D. et al. Science.2011,331,1565–1570.
(3)Cobaleda-Siles,M. et al. Small.2014,10,5054–5067.
(4)Ruiz-de-Angulo,A. et al. ACS Nano.2016,10,1602–1618.