IL1B and rheumatoid arthritis: A more recent study emphasized its significant involvement in inflammatory arthritides, in which CLU overexpression was detectable in the synovium and synovial fluid of patients with either OA or rheumatoid arthritis (RA), and CLU knockdown with small interfering RNA reportedly enhanced production of inflammatory mediators including interleukin (IL)-1β and IL-6 in RA FLSs16.