(411b) Graduate Student Award Session: Understanding How Lipid Nanoparticle Structure Affects Immune Response

Lipid-based nanoparticles have been widely demonstrated as efficacious drug delivery systems, particularly for applications in nucleic acid delivery. Despite their extensive development, however, there is limited understanding of the effect that these delivery vehicles have on the immune system. In fact, a major reason why therapeutics fail in clinical trials is due to unforeseen toxicity and/or immunogenicity. In particular, the immune system can potentially mount an antibody response to the delivery system, trigger the release of liver enzymes, or prompt an inflammatory cytokine response. Here, we describe a study of the interactions between lipidoid nanoparticles, a potent class of lipid-like RNA delivery vehicles, and the components of the innate and humoral immune system. A small combinatorial lipidoid library of 20 lipidoids was synthesized and tested for immunostimulatory effects in cell culture and animal models. In vitro analysis of RAW264.7 mouse macrophages after nanoparticle exposure indicates statistically significant rises in the gene expression of several cytokines, including tumor necrosis factor α (TNFα), for select lipid nanoparticles. Increased cytokine expression persisted for over 24 hours and depended largely on the tail structure of the lipidoid. Furthermore, the effect of lipid nanoparticles on peripheral blood mononuclear cells (PBMCs) isolated from healthy human donors was assessed via ELISA screens of TNFα, IL-1β, IFN-γ, IL-6, and IL-2. Antibody and cytokine responses were also measured following single and/or multiple intravenous injection(s) of lipid nanoparticles into C57BL/6 mice. In all cases, both the tail structure and amine structure of the lipid nanoparticle were found to be important in provoking an immune response. These structure-immune response relationships will inform the design of future drug delivery carriers and potentially mitigate failures encountered in clinical stages.