Generation of tolerogenic antigen-presenting cells in vivo via the delivery of mRNA encoding PDL1 within lipid nanoparticles.

Tolerogenic antigen-presenting cells (APCs) are promising as therapeutics for suppressing T cell activation in autoimmune diseases. However, the isolation and ex vivo manipulation of autologous APCs is costly, and the process is customized for each patient. Here we show that tolerogenic APCs can be generated in vivo by delivering, via lipid nanoparticles, messenger RNA coding for the inhibitory protein programmed death ligand 1. We optimized a lipid-nanoparticle formulation to minimize its immunogenicity by reducing the molar ratio of nitrogen atoms on the ionizable lipid and the phosphate groups on the encapsulated mRNA. In mouse models of rheumatoid arthritis and ulcerative colitis, subcutaneous delivery of nanoparticles encapsulating mRNA encoding programmed death ligand 1 reduced the fraction of activated T cells, promoted the induction of regulatory T cells and effectively prevented disease progression. The method may allow for the engineering of APCs that target specific autoantigens or that integrate additional inhibitory molecules.