GalNAc‐Conjugated siRNA Targeting Complement C3 Inhibits Osteoclast Activation in Periodontitis

ABSTRACT Objective The complement cascade plays an important role in the inflammation amplification and tissue destruction of periodontitis. Importantly, complement C3 was proved to be the central element of complement cascade. Thus, targeting inhibition of C3 has become one of the focuses of treatment method development and exploration. Methods The siRNAs targeting C3 were designed and screened for in vitro potency. The selected siRNA was conjugated to GalNAc (GalNAc‐C3 siRNA) for liver‐specific delivery. The mouse model of periodontitis was established by silk ligation. Stereomicroscopy, Micro‐CT, histological and histochemical assessment, and immunofluorescence staining were performed to evaluate the level of bone destructive and osteoclast activity. The influence of GalNAc‐C3 siRNA on inflammatory reactions was determined by qRT‐PCR, ELISA, and flow cytometry. Results GalNAc‐C3 siRNA showed great in vivo potency and durability to silence hepatic C3 mRNA expression. GalNAc‐C3 siRNA treatment could effectively inhibit the production of inflammatory cytokines (IL‐17A, TNF‐α, IL‐6, and IFN‐γ) and restrain Th17 differentiation. Importantly, the expression of RANKL and differentiation of osteoclast were inhibited by GalNAc‐C3 siRNA. Conclusion GalNAc‐C3 siRNA could efficiently play a role in bone protection by inhibiting inflammatory responses and osteoclast activities. This therapeutic siRNA may become an effective treatment strategy for periodontitis.