IL-1β stimulated human umbilical cord mesenchymal stem cells ameliorate rheumatoid arthritis via inducing apoptosis of fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is characterized by synovial proliferation and lymphocyte accumulation leading to progressive damage of the periarticular bone and the articular cartilage. The hyperplasia of the synovial intima lining mainly consists of fibroblast-like synoviocytes-rheumatoid arthritis (HFLS-RA) which exhibit apoptosis-resistance, hyper-proliferation, and high invasiveness. The therapeutic efficacy of mesenchymal stem cells (MSCs) treatment in RA has been shown to be due to its immuno-regulatory ability. However, the exact factors and mechanisms involved in MSCs treatment in RA remain unclear. In this study, TRAIL receptor-Death receptor 4 (DR4), DR5, and LFA-1 ligand-intercellular adhesion molecule-1 (ICAM-1) were upregulated in IL-1β-stimulated HFLS-RA. We demonstrated that the total cell number of IL-1β-stimulated hUCMSCs adhering to IL-1β-stimulated HFLA-RA increased via LFA-1/ICAM-1 interaction. Direct co-culture of IL-1β-stimulated hUCMSCs with IL-1β-stimulated HFLS-RA increased the apoptosis of HFLS-RA. RA symptoms in the CIA mouse model improved after administration of IL-1β-stimulated hUCMSCs. In conclusion, IL-1β-stimulated hUCMSCs adhering to HFLS-RA occurred via LFA-1/ICAM-1 interaction, apoptosis of HFLS-RA was induced via TRAIL/DR4, DR5 contact, and RA symptoms and inflammation were significantly improved in a CIA mouse model. The results of this study suggest that IL-1β-stimulated hUCMSCs have therapeutic potential in RA treatment.