Since IL-15 was involved in the pathogenesis of RA, and immunotoxins targeting IL-15R-bearing cells such as activated macrophages and T cells were reported to relieve disease severity in AA rats [59], Zhang et al. demonstrated polyethylenimine (PEI)-complexed siRNA nanoparticles to target the β chain of IL-15R, which was shared by the receptor for IL-2 (IL-2/15 receptor β chain). Here, IL2 is linked to rheumatoid arthritis.