(68c) Toll-like Receptor (TLR)-Functionalized Nanoparticle Adjuvant Carriers Toward Optimized Vaccine Formulations and Immune-Modulators

Adjuvants are molecules which enhance immune responses by stimulating various cellular pathways and are critical components of vaccine formulations. These molecules enhance the immunogenicity of synthetic antigens, which are otherwise unable to produce a robust response needed for immune protection. There are an astoundingly few clinically approved adjuvant molecules and there remains a huge unmet need for the development of novel adjuvant delivery approaches. Engineered particulate carriers offer a unique opportunity to deliver adjuvant molecules, as they can interface with key cells of the immune system for a variety of therapeutic applications, including vaccines and immunomodulation. While recent studies have demonstrated superior pre-clinical efficacy of nanoparticle vaccine formulations, surprisingly little work has been performed investigating the adjuvant component on the nanoparticle formulation. In this work, we engineer a series of particles to investigate the role of adjuvant density on the particle surface. We incorporate two toll-like-receptor (TLR) adjuvant molecules, CpG and LPS, on the surface of both cationic and anionic particle carriers and quantify the immune response in various biological environments as a function of particle characteristics. Our results indicate when dosed at equivalent particle concentrations with varied adjuvant surface densities, particles with the highest adjuvant density per particle resulted in the largest in vitro stimulation; however, when dosed at equivalent adjuvant mass per sample, particles of the lowest adjuvant density, corresponding to the highest number of particles dosed, resulted in superior stimulation. These results indicate a trade-off between adjuvant density and particle number. We believe this work provides a set of design rules which inform particulate vaccine formulations, to ensure both potency and safety, with potential future applications for novel treatments for cancer, inflammation, and allergy.