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. Author manuscript; available in PMC: 2022 Feb 9.
Published in final edited form as: JAMA. 2021 Feb 9;325(6):568–578. doi: 10.1001/jama.2020.22171

Figure 2.

Figure 2.

Molecular Mediators of Osteoarthritis. A number of pro-inflammatory factors and anabolic factors are present in joint tissues and in the synovial fluid. Pro-inflammatory mediators contribute to joint tissue destruction in large part by stimulating production of matrix degrading enzymes, including the matrix metalloproteinases, but also through inhibition of matrix synthesis. The anabolic factors stimulate matrix production and, in some cases, also inhibit the catabolic signaling stimulated by pro-inflammatory mediators. Some factors including TGFβ and bFGF are capable of initiating either catabolic or anabolic activity depending on cell type and specific receptors expressed. TGFβ and BMP-2 can also stimulate osteophyte formation. The overall activity in the OA joint is tipped in favor of the pro-inflammatory side. (IL, interleukin; LIF, leukemia inhibitory factor; MCP, monocyte chemoattractant protein, MIF, macrophage migration inhibitory factor; MIG, monokine Induced By Interferon-Gamma; bFGF, basic fibroblast growth factor; TGF, transforming growth factor; IGF, insulin-like growth factor, BMP, bone morphogenetic protein; CDMP; cartilage-derived morphogenetic protein.)