Fig. 8.

mRNA drugs elicit immunity using disease-specific targeting antigen strategies. mRNA drugs mainly go through the following three aspects from synthesis to initiate immune protection, including mRNA synthesis, intracellular processing, and initiating immune protection. Briefly, IVT mRNA drugs are encapsulated into carriers (such as nanoparticles) and are endocytosed by antigen-presenting cells (①-②); mRNA is released into the cytoplasm after escaping from endosomes and then translated into antigenic proteins by ribosomes (③). Subsequently, endogenous antigens are degraded into polypeptides by the proteasome and are presented by MHC I and activate cytotoxic T cells (CD8⁺ T cells) (④-⑥). In addition, secreted antigens can be taken up by cells, degraded inside endosomes, and presented on the cell surface to helper T cells by MHC class II proteins (⑦-⑨). Finally, helper T cells (CD4⁺ T cells) stimulate B cells to produce neutralizing antibodies against pathogens³⁸²