FAP and rheumatoid arthritis: In animal experiment, FAP-targeted zinc ferrite nanoparticles (ZF-NPs) significantly improved synovitis, reduced angiogenesis in synovial tissue, suppressed articular cartilage damage, and inhibited macrophage infiltration in mice with adjuvant-induced arthritis (108), demonstrating the potential utility of FAP-ZF-NPs in the treatment of RA.