Microbial Rhamnolipid‐Stabilized mRNA Nanovaccines Enhance Adaptive Immunity via Dendritic Cell Targeting

ABSTRACT Poly(ethylene glycol) (PEG)‐lipids endow lipid nanoparticles (LNPs) with colloidal stability but elicit anti‐PEG immunity upon repeat dosing. Here it is replaced PEG‐lipids with microbial rhamnolipids (RLs) to create PEG‐free, self‐adjuvanting LNPs. RL‐LNPs show higher than 90% mRNA encapsulation and enhanced dendritic cell uptake via the mannose receptor and DEC205, redirecting expression to lymph nodes after intramuscular injection. Compared with size‐matched PEG‐LNPs, RL‐LNPs enhance transfection and neutralizing capacity against pseudoviruses, while potently amplifying Th1‐biased humoral and cytotoxic T‐cell responses. Quantitative proteomics and western blotting reveal activation of the C‐type lectin receptor (CLR)/NF‐κB axis, corroborating intrinsic adjuvancy. Notably, RL‐LNPs avoid PEG‐associated mast‐cell infiltration under repeat dosing while maintaining favorable systemic chemistry panels and histology. These data establish glycolipids as dual‐function substitutes for PEG‐lipids, coupling stabilization with receptor‐programmed immunity for next‐generation mRNA vaccines.