Exosomes derived from synovial fibroblasts from patients with rheumatoid arthritis promote macrophage migration that can be suppressed by miR-124-3p

Objectives: Exosomes are potent vehicles for intercellular communication. Rheumatoid arthritis (RA) is a chronic systemic disease of unknown etiology. Local administration of miR-124 pre-cursor to rats with adjuvant-induced arthritis suppresses systemic arthritis and bone destruction. Thus, exosomes may be involved in this disease. We aimed to determine the role of exosomes in the pathology of RA.Methods: Fibroblast-like synoviocytes (FLS) were collected from patients with RA and osteoar-thritis (OA). miR-124-3p mimic was transfected into the RA FLS (RA miR-124 FLS). Exosomes were collected from the culture medium by ultracentrifugation. Macrophages were produced from THP-1 cells. MicroRNAs in the exosomes were analyzed using real-time PCR. Proteomics analysis was performed using nanoscale liquid chromatography-tandem mass spectrometry. Macrophage migration was evaluated using a Transwell migration assay. SiRNA was used to knockdown proteins of interest.Results: MicroRNAs in the RA FLS, RA miR-124 FLS, and OA FLS exosomes were similar. Prote-omics analysis revealed that pentraxin 3 (PTX3) levels were higher in RA FLS exosomes than in RA miR-124 FLS and OA FLS exosomes, and proteasome 20S subunit beta 5 (PSMB5) levels were lower in RA FLS exosomes than in RA miR-124 FLS and OA FLS exosomes. The RA FLS exosomes promoted and the RA miR-124 FLS exosomes suppressed macrophage migration. PTX3-silenced RA FLS exosomes suppressed and PSMB5-silenced OA FLS exosomes promoted macrophage migration.Conclusions: RA FLS exosomes promote macrophage migration via PTX3 and PSMB5, and miR-124-3p suppresses this migration.