Abstract
Adjuvants enhance immunogenicity of vaccines through either targeted antigen delivery or stimulation of immune receptors. Three cationic nanoparticle formulations were evaluated for their potential as carriers for a DNA vaccine, and muramyl dipeptide (MDP) as immunostimulatory agent, to induce and increase immunogenicity of Mycobacterium tuberculosis antigen encoding plasmid DNA (pDNA). The formulations included (1) trimethyl chitosan (TMC) nanoparticles, (2) a squalene-in-water nanoemulsion, and (3) a mineral oil-in-water nanoemulsion. The adjuvant effect of the pDNA-nanocomplexes was evaluated by serum antibody analysis in immunized mice. All three carriers display a strong adjuvant effect, however, only TMC nanoparticles were capable to bias immune responses towards Th1. pDNA naturally contains immunostimulatory unmethylated CpG motifs that are recognized by Toll-like receptor 9 (TLR-9). In mechanistic in vitro studies, activation of TLR-9 and the ability to enhance immunogenicity by simultaneously targeting TLR-9 and NOD-like receptor 2 (NLR-2) was determined by proinflammatory cytokine release in RAW264.7 macrophages. pDNA in combination with MDP was shown to significantly increase proinflammatory cytokine release in a synergistic manner, dependent on NLR-2 activation. In summary, novel pDNA-Ag85A loaded nanoparticle formulations, which induce antigen specific immune responses in mice were developed, taking advantage of the synergistic combinations of TLR and NLR agonists to increase the adjuvanticity of the carriers used.
Highlights
Vaccination by direct injection of antigen encoding plasmid DNA has been evaluated for decades
After adsorption of plasmid DNA (pDNA), the size increased for trimethyl chitosan (TMC) nanoparticles (p < 0.001) and both nanoemulsions (p < 0.0001), while the zeta potential decreased drastically to
We showed that receptor-interacting serine/threonine-protein kinase 2 (RIP2) blocking led to significant reduction of cytokine release, leading to reduced cytokine release for ligands applied in solution (p < 0.05), for TMC nanoparticle-conjugates (p < 0.01) and for ligands applied with SWE06 (p < 0.001) and Cationorm® (p < 0.01) nanoemulsions, respectively, compared to untreated cells (Figure 6)
Summary
Vaccination by direct injection of antigen encoding plasmid DNA (pDNA) has been evaluated for decades. SWE06), and the commercially available cationic nanoemulsion, Cationorm® These particles were compared for their adjuvant potential to increase immunogenicity of pDNA in mice. In an in vivo experiment in mice we compared TMC nanoparticles, SWE06, and Cationorm® as pDNA delivery systems to increase Th1 related immune responses against Ag85A. Following these investigations, we exploited the potential of concurrent activation of two non-redundant PRR pathways in vitro with the aim of further optimizing immunogenicity of pDNA. Our results show that cationic TMC nanoparticles are promising carriers for pDNA and co-delivery with MDP can be used to further increase immunogenicity of this DNA vaccine formulation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
