Fig. 2

The main inflammatory signaling pathways affected by NPs during OA treatment. NPs inhibit NF-κB pathway by inhibiting IκB degradation and p65 translocation into the nucleus, as well as phosphorylation of p65. NPs inhibit the phosphorylation of PI3K, mTOR and AKT in PI3K/AKT pathway. NPs also prevent the phosphorylation of p38, JNK and ERK, thereby blocking the activation of MAPKs-related pathways. In addition, NPs can inhibit the SIRT1-mediated activation of NF-κB pathway, thereby reducing the IL-1β-induced expression of inflammatory mediators in chondrocytes. The inhibition of above signaling pathways by NPs decrease the production of several inflammatory factors, including PGE2, NO, IL-1β, IL-6, iNOS, COX2, etc.