ADORA2B, deubiquitinated by USP14, facilitates IL-1β-induced chondrocyte apoptosis, ferroptosis and inflammation to accelerate osteoarthritis process

BACKGROUND: Abnormal expression of adenosine A2B receptor (ADORA2B) may be involved in the development of osteoarthritis (OA). Therefore, it is necessary to explore its role and mechanism in OA progression to understand OA pathogenesis. METHODS: Chondrocytes were treated with IL-1β to induce an OA cell injury model. Chondrocyte proliferation and apoptosis were detected using CCK8 assay, EdU assay, and flow cytometry. The levels of inflammation factors were examined by ELISA. Fe2+, ROS, lipid ROS, MDA, and GSH levels were determined to evaluate cell ferroptosis. ADORA2B mRNA expression was tested by quantitative real-time PCR. ADORA2B, GPX4, and ubiquitin-specific peptidase 14 (USP14) protein levels were examined by western blot. The interaction between ADORA2B and USP14 was assessed by Co-IP assay. RESULTS: IL-1β treatment decreased chondrocyte proliferation, enhanced apoptosis, inflammation, and ferroptosis. ADORA2B had elevated expression in OA patients and IL-1β-induced chondrocytes. Downregulation of ADORA2B suppressed IL-1β-induced chondrocyte injury. In terms of mechanism, USP14 positively regulated ADORA2B expression through deubiquitination. USP14 knockdown also inhibited IL-1β-induced chondrocyte apoptosis, inflammation, and ferroptosis, while these effects were overturned by ADORA2B overexpression. CONCLUSION: ADORA2B, mediated by the deubiquitination of USP14, accelerated IL-1β-induced chondrocyte apoptosis, inflammation, and ferroptosis to facilitate OA progression, providing a novel target for OA treatment.