microRNA-controlled mRNA therapeutics

Nucleoside modified RNA-based drugs (modRNA) are a powerful new class of medicine. One type of modRNA, RNA vaccines, has been pivotal in immunization to SARS-CoV-2. modRNA is delivered via lipid nanoparticles (LNP), and antigen presented by whichever cells take up and expresses the modRNA. The identity and phenotypic state of cells presenting antigen directs how T cells become activated and differentiate. FDA-approved LNPs for modRNA delivery are not cell specific, resulting in expression in pAPCs, hepatocytes, myocytes, and other cells. The contributions of different transfected cell types to the immune response to modRNA-encoded proteins is not known. This is an important question because antigen presentation by some cell types may work against therapeutic goals. While there are efforts to alter LNP organ distribution, precisely tailored cell specificity is still not feasible. We previously developed a technology that enables highly effective cell type specific silencing of vector-expressed RNA. We showed target sites for miRNA (miRT) could be incorporated into the 3’UTR of a transgene, and when the transgene is expressed in cell types that encodes the cognate miRNA, transgene expression is suppressed. Work by numerous labs, including ours, has demonstrated miRT can de-target vector expression from many cell types, including hepatocytes, hematopoietic cells, pAPC, stem cells, and neurons. Preliminary and published data indicate that adding target sites for miR-142 (142T) or miR-122 (122T) to modRNA silences modRNA expression in hematopoietic cells or hepatocytes, respectively, demonstrating the technology can be used to control modRNA expression. Our objective is to use miRT to generate modRNA with tailored cell expression patterns and apply miRT to determine how modRNA expression in specific cell types directs immunity to modRNA-encoded protein. We hypothesize modRNA expression in non-pAPCs, such as hepatocytes, reduces immunity to modRNA-encoded proteins by presenting antigen in a tolerogenic context, and this lowers vaccine efficacy but can be exploited for tolerance. We will generate and test miRT for silencing modRNA in different cell types, including endothelium & myocytes, and determine how modRNA expression in different transfected cells, such as hepatocytes, influences immunity to modRNA antigen. The outcome of this project will establish novel modRNA configurations that tailor expression of proteins to specific cell types and determine how expression in specific cell types directs immunity to modRNA-encoded protein.