TLR3 and rheumatoid arthritis: TLR3 is expressed in RA synoviocytes, and activation of TLR3 signaling induces the expression of various cytokines including vascular endothelial growth factor, interleukin-8 [8], C-C motif chemokine ligand 5 and C-X-C motif chemokine ligand 10 (CXCL10) [9].