IDO1 and rheumatoid arthritis: However, when GILZ and IFN-γ are knocked out, these MSCs lose their ability to improve joint swelling in rheumatoid arthritis (RA) mouse models (Luz-Crawford et al. 2015; Schurgers et al. 2010) The immunomodulatory function of BMMSCs may also depend on the expression of inducible nitric oxide, programmed death ligand -1 (PD-L1), and prostaglandin E2 (PGE2) rather than IDO (Schurgers et al. 2010).