Polyelectrolyte Multilayer Films for the Activation of the Cgas-Sting Cytosolic DNA Sensing Pathway

Particulate vaccine formulations rely on the phagocytosis of particles loaded with immunostimulatory signals by antigen presenting cells, but lack an active mechanism to efficiently transport these signals to the cytosol. In order to address this, we cosynthesized dimethylaminoethyl methacrylate (DMAEMA) with butyl methacrylate (BMA) and propylacrylic acid (PAA) to form DMAEMA-b-(PAA-c-BMA-c-DMAEMA) polymer through reversible addition fragmentation chain transfer (RAFT) polymerization. This polymer self-assembles into cationic micellar nanoparticles that are capable of forming films with polyanions through layer-by-layer deposition. Films consisting of this polymer and Immunostimulatory DNA (ISD), an immunogenic DNA strand known to activate the cGAS-STING cytosolic DNA sensing pathway, were grown onto 3 um diameter calcium carbonate microparticles. The growth of these films was studied using fluorescence spectroscopy to detect a label on the polymer and was shown to demonstrate an exponential growth pattern. Next, we tested the immunogenicity and toxicity of the coated particles by transfecting a blue reporter human monocyte THP1 cell line and measuring the resulting immune response and cell viability. Results indicate that particles with 5 or 6 bilayers of polymer and ISD are capable of eliciting a significant immune response. Furthermore, varying the ISD dosage at 5 bilayers resulted in increased activation of interferon expression. These thin film particles have the potential to increase delivery of immunomodulatory cargo to the cytosol and thereby enhance the efficacy of particle-based vaccines.