TIMP3 and rheumatoid arthritis: OPN301 significantly reduced spontaneous secretion of MMP-3 from the RA explants compared to IgG control (p <0.05) (Fig. 6a (i)), resulting in a significant reduction in the MMP-3:TIMP-3 ratio (Fig. 6a (iii)) (p <0.05), thus favouring an MMP/TIMP balance against joint destruction.