TLR4 and Arthritis: The findings are in line with results of TLR4 inhibition with a naturally occurring antagonist in the collagen induced arthritis model and the IL-1ra −/− model [4], the KRN serum transfer arthritis [20] as well as with results from the antigen-induced arthritis model [11], for which tenascin was identified as critical endogenous ligand of TLR4.