TNFSF11 and rheumatoid arthritis: Exosomes originating from RA FLS affect the RANKL/RANK/osteoprotegerin (OPG) pathway by transporting miR-106b to chondrocytes and inhibiting pyruvate dehydrogenase kinase isozyme 4 (PDK4), which inhibits chondrocyte proliferation and migration and accelerates apoptosis.