Caffeic acid phenethyl ester attenuates osteoarthritis progression by activating NRF2/HO-1 and inhibiting the NF-κB signaling pathway

Osteoarthritis (OA) is the most common degenerative disease affecting the joints, and inflammation appears to play a critical role in the initiation and progression of OA. Caffeic acid phenethyl ester (CAPE), a natural flavonoid compound, has anti-inflammatory and antioxidant functions. However, its anti-inflammatory effects on OA and the underlying mechanisms of action of CAPE in the treatment of OA remain elusive. Therefore, the present study investigated the anti-inflammatory effects of CAPE on IL-1 beta-stimulated chondrocytes in vitro and surgically induced rat models of OA in vivo. In vitro, CAPE reduced the expression of inducible nitric oxide synthase and cyclooxygenase-2 in IL-1 beta-stimulated chondrocytes, as well as the extracellular secretion of nitric oxide and prostaglandin E2 in the cell culture supernatants. In addition, CAPE attenuated the degradation of extracellular matrix by increasing the expression of aggrecan and collagen II, and decreasing the expression of MMP3, MMP13 and a disintegrin and metalloproteinase with thrombospondin motif-5. Furthermore, CAPE attenuated NF-kappa B signaling and activated the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling pathway in IL-1 beta-stimulated chondrocytes. In vivo, CAPE protected cartilage from destruction and delayed the progression of OA in rats. Taken together, the findings of the present study indicated that CAPE may be a potential therapeutic agent for the prevention or treatment of OA.