Background/Purpose: Chemokine C-C motif ligand 11 (CCL11) also known as eotaxin-1 is produced by a variety of cell types. By interacting with C-C chemokine receptor 3 (CCR3), CCL11 stimulates the migration of several types of cells. High levels of CCL11 and CCR3 have described in rheumatoid arthritis (RA). Previously, we reported that the expression of CCL11 was increased by tumor necrosis factor (TNF) -α stimulation in RA fibroblast-like synoviocytes (FLS). A recent study reported that receptor activator of nuclear factor kappa-B ligand stimulated CCR3 expression in osteoclasts and the addition of CCL11 caused an increased migration of pre-osteoclast and an increase in osteoclastic bone resorption. The aim of this study is to investigate the expression and the function of CCL11 in RA.

Methods: The levels of CCL11 were determined in serum from healthy control (HC) and RA patients in onset using enzyme-linked immunosorbent assay (ELISA). We also measured the levels of CCL11, TNF-α and MCP-1 in synovial fluids (SFs) from the patients with RA and osteoarthritis (OA). To investigate the expression of CCL11 or CCR3 in RA FLS, cells were left unstimulated or were stimulated with recombinant TNF-α or CCL11. After stimulation, the protein expression levels in the culture medium were measured by ELISA and the messenger (mRNA) expression levels were measured by quantitative polymerase chain reaction analysis. The expression of CCL11 or CCR3 on RA FLS were also demonstrated by immunohistochemistry. To confirm the role of CCL11 in cell migration, RA FLS were stimulated with recombinant CCL11 and were allowed to migrate through uncoated transwell chambers. Finally, to block the expression of CCL11, RA FLS were transfected with small interfering RNA (siRNA) against CCL11, and proinflammatory cytokines in TNF-α stimulated RA FLS conditioned medium were measured using ELISA.

Results: The levels of CCL11 in the serum from RA (n=26) were higher than those in the serum from HC (n=28) (median [IQR]; 78.3 [62.7-114.1] pg/mL and 46.8 [30.9-67.7] pg/mL, p<0.05, respectively). The levels of CCL11 in SFs from the patients with RA (n=15) were higher than those in SFs from the patients with OA (n=16) (20.3 [5.3-26.3] pg/mL and 4.1 [0.2-9.0] pg/mL, p<0.05, respectively) and were positively correlated with the levels of TNF-α (r=0.74, p<0.05) and MCP-1 (r=0.64, p<0.05). The mRNA expression of CCL11 and CCR3 in RA FLS were increased by TNF-α stimulation (p<0.05). In addition, we confirmed that the expression of CCL11 and CCR3 were increased with TNF-α stimulation using immunohistochemistry. Furthermore, the expression of CCR3 mRNA were increased by CCL11 stimulation (p<0.05). CCL11 stimulated cells were significantly higher efficient at migration than unstimulated cells (p<0.05). CCL11 siRNA treatment decreased the expression of MCP-1 in TNF-α treated RA FLS conditioned medium (p<0.05).

Conclusion: These data show that CCL11 and CCR3 are increased by TNF-α stimulation in RA FLS and CCL11 is associated with RA FLS migration and the secretion of MCP-1. CCL11 may play an important role of inflammation in RA.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ccl11-is-involved-in-cell-migration-in-rheumatoid-arthritis/