Enhancing responses to mRNA-lipid nanoparticle vaccines via utilization of endogenous lipid function - ABSTRACT mRNA - lipid nanoparticle (LNP) vaccines developed against SARS-CoV-2 proved to be a transformative technology that saved millions of lives during the COVID-19 pandemic. In this vaccine platform, LNPs function as both a delivery agent and a powerful adjuvant, but the mechanisms contributing to LNP adjuvanticity are not fully understood, hindering future vaccine design. In this proposal I will investigate how selectively altering the lipids within an LNP impacts biodistribution and cell-specific protein translation from mRNA following intramuscular administration, and whether these alterations can promote stronger cellular and humoral adaptive immune responses. Phosphatidylserine (PS) is a negatively charged phospholipid normally present on the inner leaflet of a cell’s plasma membrane but can become exposed on the outer leaflet during apoptosis. When this occurs, PS is sensed by scavenger receptors of phagocytic antigen presenting cells (APCs), triggering phagocytosis. Globotriaosylceramide (Gb3) is a glycosphingolipid that promotes migration of germinal center B cells from the dark zone to the light zone by enhancing a B cell receptor (BCR) signaling cascade that results in a decrease of CXCR4 expression. By incorporating these endogenous lipids into LNP formulations, this proposal will test if they can direct cell and tissue-specific protein expression from mRNA-LNPs, and if they can impact humoral and cellular immune responses. In Aim 1 I will determine the cellular uptake pathway for these modified LNPs in vitro and their biodistribution in vivo. In Aim 2 I will elucidate how incorporation of PS and Gb3 lipids into LNPs impacts adaptive immune responses in vivo. Overall, I hypothesize that adaptive immune responses to mRNA-lipid nanoparticle vaccines can be specifically modulated based on incorporation of endogenous lipids into the LNP formulation. The ability to alter immune responses to mRNA-LNP vaccines by leveraging endogenous lipid function within an LNP would be hugely beneficial in creating more tailored, effective vaccines against both existing and emerging infectious pathogens.
