An imbalance between MMP-3 and TIMP-1 has been observed in inflammatory conditions such as RA, with IL-17/TNF contributing in synergy to the increased MMP/TIMP ratio [30–32].The possible increase of MMPs/TIMP-1 ratio in association with the increased level of MT1s after exposure to cytokines and metal was measured. This evidence concerns the gene MT1A and rheumatoid arthritis.