The effect of caveolin-1 knockdown on interleukin-1β-induced chemokine (C-C motif) ligand 2 expression in synovial fluid-derived fibroblast-like synoviocytes from patients with rheumatoid arthritis

Background. Rheumatoid arthritis (RA) is a chronic autoimmune disease leading to destructive changes in peripheral joints and their irreversible deformity. The influx of chemoattractant-mediated inflammatory cells to the joints is one of the main features of RA. Objectives. The aim of this study was to investigate the effect of a knockdown of caveolin-1 (CAV1), a known regulator of multiple cell signaling pathways, on chemokine (C-C motif) ligand 2/monocyte chemoattractant protein-1 (CCL2/MCP-1) expression in synovial fluid-derived fibroblast-like synoviocytes (sfd-FLSs) obtained from patients with RA. Material and methods. Primary cell cultures of sfd-FLSs were established from RA synovial fluids. Cells were transiently transfected with small interfering RNA (siRNA) specific for CAR and then incubated with interleukin (IL)-1 beta to induce CCL2 expression. The expression levels of CAV1 and CCL2 were assessed at transcript level, using quantitative polymerase chain reaction (qPCR) and at protein level by enzyme-linked immunosorbent assay (ELISA) and western blotting analysis. Results. A transient CAV1 knockdown in sfd-FLSs resulted in a decrease in the IL-1 beta-induced CCL2 mRNA expression level vs non-transfected cells and cells transfected with non-targeting siRNA. The concentration of secreted CCL2 was not affected significantly. Conclusions. Our study demonstrates that CCL2 expression in sfd-FLSs is CAV1-dependent, but only at transcript level. As the function of CAV1 has not been unequivocally determined, more studies are needed to confirm the role of CAV1 in inflammatory processes related to RA.