Autophagy promotion enhances the protective effect of Morroniside on human OA chondrocyte.

Morroniside plays a therapeutic role in knee osteoarthritis (OA) by protecting chondrocytes. PI3K/AKT signaling is involved in the regulation of chondrocytes by Morroniside. PI3K/AKT suppresses autophagy through downstream signaling. However, the regulation of chondrocyte autophagy by Morroniside and the significance of the above effect on protecting chondrocytes aren't clear. The results showed that Morroniside inhibited the autophagiy of human OA chondrocytes. Besides, both PI3K inhibitors and mTOR inhibitors significantly reversed the autophagy reduced by Morroniside, but had no effect on the protective effect of Morroniside on chondrocytes. However, the enhanced autophagy caused by overexpression of autophagic genes enhanced the protective effect of Morroniside on chondrocytes. In conclusion, Morroniside represses the autophagy of human OA chondrocyte, which is related to PI3K/mTOR pathway. Moreover, the upregulation of autophagy further promoted the role of Morroniside in treating chondrocytes. Our data present a potential clue for the therapeutic strategies of Morroniside in treating OA.