RNA interference on TLR9 expression affects the response of bone marrow-derived murine dendritic cells to CpG

摘要

Toll-like receptors 9 (TLR9) are expressed intracellularly by dendritic cells (DC) and specifically recognize unmethylated CpG motif. CpG DNAs though TLR9 can induce DC maturation following by the subsequent immune responses. Here, we use RNAi to identificate CpG DNA signaling receptor. It is demonstrated in this article that transfection of DCs with siRNA specific for TLR9 gene can significantly down-regulate TLR9 expression. When exposed to CpG, immature DCs transfected with TLR9 siRNA can not differentiate into mature DCs. TLR9 siRNA-treated DCs express low lever MHCII and CD40 without reducing endocytosis. Furthermore, TLR9 siRNA-transfected DCs exhibited a decreased allostimulatory capacity in a lymphocyte proliferation assay and attenuated Thl responses by decreasing IL-12p70 production. Our findings indicate that silencing the TLR9 gene in DCs with siRNA may offer a potential tool to study the TLR9-CpG pathway.