Glabridin inhibits osteoarthritis development by protecting chondrocytes against oxidative stress, apoptosis and promoting mTOR mediated autophagy

Osteoarthritis (OA) is a common chronic degenerative disease that affects the elderly. Thus far, no pharmacological therapy approved by regulators has shown a convincing effect on OA. Glabridin, a small molecule, is a well-known and powerful natural antioxidant, which has a strong scavenging effect on free radicals. This study attempted to explore the role and underlying mechanisms of Glabridin on OA both in vitro and in vivo. In the in vitro study, Glabridin was found to increase the expression levels of extracellular matrix (ECM) related genes, Collagen II, Aggrecan (ACAN), SRY-box 9 (SOX9) and proteoglycan 4 (PRG4). Moreover, Glabridin was observed to significantly reduce the level of oxidative stress in OA chondrocytes while effectively reducing the apoptosis of chondrocytes. Glabridin was also found to significantly increase the autophagy of human OA chondrocytes. During the in vivo study, intraarticular injection of Glabridin was observed to alleviate OA progression and protect chondrocytes against apoptosis following anterior cruciate ligament transection (ACLT) in rats. Furthermore, the mammalian target of rapamycin (mTOR) mediated autophagy was identified as one of the potential mediators of Glabridin activity. Overall, Glabridin protects articular cartilage from damage in rats with OA by protecting chondrocytes against oxidative stress, apoptosis and promoting mTOR mediated autophagy.