MMP13 and rheumatoid arthritis: Interestingly, the inflammatory markers analyzed in this work, and in particular il6, il8, and mmp13, were found to be upregulated also in osteoarthritis (OA) and rheumatoid arthritis (RA), the two most common types of arthritis [74,75,76,77,78], providing a clue to the possible mechanisms used by these molecules against these painful pathologies.