CCL21 and synovitis: Belluzi et al. also demonstrated, that CM from OA tissues, such as CRT, IFP, meniscus, and synovium, induced and increased IL-8 and CCL21 production in the synoviocyte cell line and confirmed that CM from all OA joint tissues could contribute to the progression of synovitis, with SM playing a predominant role compared to other joint tissues [26].