FIRN

FIRN is an experimental biomimetic nanoparticle therapeutic designed for the treatment of rheumatoid arthritis (RA). It consists of a nanoparticle core coated with the cell membrane of regulatory fibroblast-like synoviocytes (FLSreg). These regulatory fibroblasts are induced from primary FLS through treatment with interferon-gamma (IFN-γ) and rapamycin, a process that shifts the cells from a proinflammatory phenotype to an immunosuppressive regulatory phenotype characterized by the high expression of inhibitory surface molecules. FIRN utilizes the natural joint-homing properties of the synoviocyte membrane to target inflamed synovial tissues, where it suppresses T-cell activation and promotes the resolution of inflammation. Preclinical studies in mouse models of RA have demonstrated that FIRN is stable, effectively targets joints, and significantly reduces disease severity by restoring immune tolerance.