IL1B and synovitis: In order to address its beneficial action as an anti-inflammatory molecule in knee OA synovitis, we aimed to determine whether CLU has a protective effect against IL-1β-induced inflammation in knee OA FLSs through counteracting activation of PI3K/Akt signaling pathway and to investigate its mRNA and protein levels in the systemic and local joint environment of knee OA patients with and without synovitis.