uPB-Exo selectively accumulated in activated fibroblast-like synoviocytes and acted as mimics of SOD2 and NOX2 in inflamed joints of RA in vivo, subsequently neutralizing proinflammatory factors, alleviating inflammatory synovitis and protecting against cartilage damage in an advanced RA mouse model (Zhang et al., 2022). The gene discussed is SOD2; the disease is rheumatoid arthritis.