TLR9 and rheumatoid arthritis: Notably, inhibiting NET formation (e.g., FcαRI antibody, celastrol), blocking NET-mediated inflammation (e.g., RAGE/TLR9 antagonists), and clearing NET remnants to break the pathogenic cycle (e.g., PAD enzyme inhibitors, DNase I and CD19 CAR-T trials) provide novel strategies for RA treatment.