4-Octyl itaconate protects chondrocytes against IL-1ß-induced oxidative stress and ferroptosis by inhibiting GPX4 methylation in osteoarthritis.

ABSTRACT

The role of oxidative stress and ferroptosis in osteoarthritis (OA) pathogenesis is increasingly recognized. Notably, 4-octyl Itaconate (OI) has been documented to counteract oxidative stress and inflammatory responses, highlighting its therapeutic potential in OA. This study explored the effects of OI on GPX4 methylation, oxidative stress, and ferroptosis in chondrocytes affected by OA. Our results demonstrated that OI mitigated IL-1ß-induced chondrocyte degeneration in a dose-dependent manner. It also suppressed reactive oxygen species (ROS) production and sustained GPX4 expression, thereby attenuating the degenerative impact of IL-1ß and Erastin on chondrocytes by curtailing ferroptosis. Moreover, we observed that blocking GPX4 methylation could alleviate IL-1ß-induced degeneration, oxidative stress, and ferroptosis in chondrocytes. The regulatory mechanism of OI on GPX4 expression in chondrocytes involved the inhibition of GPX4 methylation. In a mouse model of OA, OI's protective effects against OA were comparable to those of Ferrostatin-1. Thus, OI reduced chondrocyte degeneration, oxidative stress, and ferroptosis by inhibiting GPX4 methylation, offering a novel mechanistic insight into its therapeutic application in OA.