CD4 aptamer-RORγt shRNA chimera inhibits IL-17 synthesis by human CD4⁺ T cells

Cell type specific delivery of RNAi to T cells has remained to be a challenge. Here we describe an aptamer mediated delivery of shRNA to CD4⁺ T cells targeting RORγt to suppress Th17 cells. A cDNA encoding CD4 aptamer and RORγt shRNA was constructed and the chimeric CD4 aptamer-RORγt shRNA (CD4-AshR-RORγt) was generated using in vitro T7 RNA transcription. 2′-F-dCTP and 2′-F-dUTP were incorporated into CD4-AshR-RORγt for RNase resistance. CD4-AshR-RORγt was specifically uptaken by CD4⁺ Karpas 299 cells and primary human CD4⁺ T cells. The RORγt shRNA moiety of CD4-AshR-RORγt chimera was cleaved and released by Dicer. Furthermore, CD4-AshR-RORγt suppressed RORγt gene expression in Karpas 299 cells and CD4⁺ T cells and consequently inhibited Th17 cell differentiation and IL-17 production. These results demonstrate that aptamer-facilitated cell specific delivery of shRNA represents a novel approach for efficient RNAi delivery and is potentially to be developed for therapeutics targeting specific T cells subtypes.