Objective: Small interfering RNA (siRNA) triggers RNA interference in mammalian somatic cells. TNF-Ձ is a proinflammatory cytokine implicated in the pathogenesis of inflammatory arthritis including rheumatoid arthritis (RA). This study was to use TNF receptor 1 (TNFRI)- specific siRNA to inhibit the TNF-Ձ mediated signaling in RA fibroblast like synoviocytes (FLS) and chondrocytes. Methods: TNFRI specific siRNA was produced by targeting 3 nucleotide sequences at 474∼494, 562∼582 and 668∼688. Reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot were performed to optimize the silencing effects of TNFRI siRNA in cultured FLS and chondrocytes. The inhibition of TNF-Ձ mediated signaling was determined by ELISA assay of metalloproteinase 1 secretion induced by TNF-Ձ. Results: The TNFRI siRNA inhibited the expression of TNFRI mRNA and protein in both RA FLS and chondrocytes. MMP-1 secretion induced by TNF-Ձ was significantly downregulated by TNFRI siRNA. Conclusion: TNFRI siRNA can inhibit the expression and signaling downstream of TNFRI in both RA FLS and chondrocytes efficiently. This suggests that RNA interference technique by siRNA could be considered as a potential therapeutic target for RA.

Keywords: Rheumatoid arthritis, siRNA, TNF-Ձ,, TNF receptor 1, Metalloproteinasepocomplementemia