CXCL9 and rheumatoid arthritis: CXCL9 was significantly overexpressed in fibroblasts and monocytes from the RA synovium and according to previous reports, its knockdown by exosomes containing miR-320a suppressed the activation, migration, and invasion of RA-FLS and decreased the arthritis index and inflammatory score in the CIA model (Meng and Qiu, 2020).