Targeting CpG Oligonucleotides to the Lymph Node by Nanoparticles Elicits Efficient Antitumoral Immunity

Abstract

Viral nucleic acids are recognized by specific pattern-recognition receptors of the Toll-like and RIG-I-like receptor families. Synthetic DNA and RNA oligonucleotides can activate the immune system through these receptors and potentiate Ab and CD8 cytotoxic responses to Ags. Systemic application of immunostimulatory oligonucleotides however also results in a generalized, non-Ag-specific stimulation of the immune system. In this study, we have dissociated the induction of an Ag-specific response from the systemic immune activation generally associated with immunostimulatory oligonucleotides. Delivery of CpG oligodeoxynucleotides that bind TLR9 by cationized gelatin-based nanoparticles potentiates the in vivo generation of an Ag-specific cytotoxic T cell and Ab response. Furthermore, immunization with CpG-loaded nanoparticles induces a protective antitumoral response in a murine model of melanoma. The systemic release of proinflammatory cytokines and widespread immunostimulation associated with free CpG is however completely abolished. In addition, we show that gelatin nanoparticle formulation prevents the destruction of lymphoid follicles mediated by CpG. Nanoparticle-delivered CpG, in contrast to free CpG, are selectively targeted to APCs in the lymph nodes where they mediate local immune stimulation. We describe a novel strategy to target immunostimulatory oligonucleotides to the initiation site of the immune response while at the same time protecting from an indiscriminate and generalized activation of the immune system.

Enhancing Efficacy of Anticancer Vaccines by Targeted Delivery to Tumor-Draining Lymph Nodes

“…17, 31, 38). Our nanoparticles were in the range of 30 nm, thus smaller than particles used in many vaccination studies, hence affording enhanced lymphatic drainage and targeting of the skin-draining LNs (14)(15)(16)(17)(18)(19).…”

“…Strategies based on delivering adjuvants or antigens carried by nanoparticles or liposomes have led to improved targeting of LNs, activation of LN-resident DCs, and enhanced induction of antigen-specific CD8 þ T cells, hence better protection in tumor challenge studies (14)(15)(16)(17)(18)(19). Ultrasmall, functionalizable nanoparticles (NP) developed in our laboratory effectively target DCs in skin-draining LNs upon intradermal delivery (20,21).…”

Nanoparticulate CpG Immunotherapy in RAO‐Affected Horses: Phase I and IIa Study

“…A recognition receptor for CpG‐ODN is the toll‐like‐receptor‐9 (TLR‐9) which has been identified in macrophages, bronchial epithelial cells, capillary endothelial cells, and neutrophil granulocytes in equine lungs 12. Drug delivery systems such as lipid13 or gelatin nanoparticles (GNPs) have been used to protect CpG‐ODN in vivo against nuclease degeneration 14, 15. GNPs represents a highly efficient drug delivery system, which also has the advantages of being aerodynamically stable after inhalation, immunologically inert, biodegradable, and biocompatible 14, 15, 16, 17, 18, 19…”

Polymer-based nanoparticles loaded with a TLR7 ligand to target the lymph node for immunostimulation

“…This targeting has been shown to enhance cytotoxic T-cell responses when the TLR7 agonist is applied together with antigen in the context of vaccination (Jewell et al, 2011;Nuhn et al, 2016). In addition, lymph node targeting of TLR ligands can reduce systemic levels of proinflammatory cytokines (Bourquin et al, 2008). We propose that mPEG-PLA and PLGA/mPEG-PLA nanoparticles represent an attractive and safe delivery system to target small molecule TLR7 agonists to lymph nodes, allowing a focused immune response that may be of benefit for anticancer immunotherapy.…”