Fig. 1

Comparison of the microenvironment between normal and OA joint cavities. Synovial thickening, synovial inflammation, massive activation of inflammatory M1 macrophages, articular cartilage erosion, and the release of a large number of inflammatory factors (including TNF-α, IL-1, IL-12, IL-6, and IL-16), increase in the levels factors responsible for cartilage destruction, and destruction of factors responsible for cartilage formation occur. B cells、T cells、mast cells and NK cells infiltrate into the joint cavity. The imbalance in the homeostasis of the OA joint cavity microenvironment promotes the formation and progression of OA