Figure 7.

Graphical summary of the crosstalk between cartilage and FLS involving CypB-CD147 signaling in CIA cartilage-synovioctyes coculture system. Upon being challenged by IL-1, CIA cartilage rapidly produces MMPs (e.g., MMP-3, MMP-9, and MMP-13) and releases CypB. As a paracrine proinflammatory cytokine, CypB interacts with CD147 which expresses on the membrane of CIA FLS. Activated by CD147, translocation of NF-κB into the nucleus occurs, followed by a subsequent secretion of inflammatory cytokines, which in turns aggravates the inflammation of cocultured cartilage. Consequently, a vicious circle loop starts.