In arthritis progression, trained macrophages reduce fibroblast‐like synoviocytes’ (FLS) lipid peroxidation, lessening sensitivity to iFSP1‐induced ferroptosis through interleukin‐1 beta (IL‐1β)/N‐acetyltransferase 10 (NAT10)/ferroptosis suppressor protein 1 (FSP1) mRNA ac4C modification. The gene discussed is AIFM2; the disease is arthritic joint disease.