Artemisinin increases susceptibility to ferroptosis of fibroblast-like synoviocytes in rheumatoid arthritis

OBJECTIVE: Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by extensive synovial hyperplasia. Artemisinin (ART), a compound extracted from the traditional Chinese herb artemisia annua, has been proven to have anti-malarial and anti-cancer effects. Recently, the ability of artemisinin to induce ferroptosis has shown inhibitory effects on tumor cell proliferation. This study intends to examine whether artemisinin can inhibit the proliferation of RA synovial cells by sensitizing them to ferroptosis. METHOD: The effect of artemisinin on fibroblast-like synoviocytes (FLSs) were detected by methods such as CCK8, Western Blot, and immunofluorescence. A collagen-induced mouse model of rheumatoid arthritis was established by injecting collagen and Freund's adjuvant, and the mice were treated with artemisinin following model induction. Synovium was extracted, and imaging examinations along with immunostaining were used to identify the progression of ferroptosis. RESULTS: The results revealed that ART increases the susceptibility of FLSs to ferroptosis inducers. The expression of ferroptosis-related proteins, such as glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11), was decreased compared with controls. Meanwhile, intracellular lipid peroxides continued to accumulate after artemisinin treatment. Additionally, ferroptosis inhibitors such as deferoxamine (DFO) and Ferrostatin (Fer-1) can inhibit artemisinin-sensitized ferroptosis. The artemisinin-sensitized ferroptosis was related to the increase of P53. In vivo experiments on collagen-induced arthritis mouse models further confirmed that artemisinin relieved joint injury by sensitizing synovial ferroptosis, which was abolished by ferroptosis inhibitors. CONCLUSION: Artemisinin can increase the sensitivity of FLSs to ferroptosis and inhibit the proliferation of synovial cells in rheumatoid arthritis. The P53-SLC7A11 pathway play the important role in this process.