CAT and Arthritis: Apart from the direct effect of MMPs on ECM degradation in cartilage and promoting the progression of arthritis, endogenous antioxidants such as superoxide dismutases (SODs), glutathione peroxidase (GPx), catalase (CAT), and glutathione reductase (GR) also affect the occurrence of arthritis by scavenging intracellular reactive oxygen species (ROS) and alleviating cellular oxidative stress.