Effects of interleukin-34 on the proliferation and chemokines expression of fibroblast-like synoviocytes in patients with rheumatoid arthritis

Abstract

Objective To investigate the effects of interleukin (IL)-34 on the proliferation and chemokines expression of fibroblast-like synoviocytes (FLS) in patients with rheumatoid arthritis (RA). Methods RA FLS were isolated and cultured in the presence or absence of IL-34. FLS proliferation was determined by methyl thiazlyl tetrazoliu method (MTT) method. The levels of chemokines from RA FLS supernatant were detected by protein chip AAH-CYT-G1000 assay. The IL-34 receptor (IL-34R) expression on RA FLS was analyzed by flow cytometry (FCM). Statistical analysis between groups was performed by t test. Results Compared to the control group, the proliferation of IL-34-stimulated RA FLS was obviously increased, and up to the maximum at 72 hours. In addition, the levels of chemokines [epithelial neutrohil-activating peptide 78(ENA-78), IL-8, growth-related oncogene (GRO), macrophage chemoattractant protein-1 (MCP-1)] on RA FLS supernatant in IL-34 stimulated group were significantly elevated than those in the control group [ENA-78: (397.1 ±8.2) pg/ml, (54.0±2.9) pg/ml (t=127.61, P<0.01); IL-8: (2 017±36) pg/ml, (778±102) pg/ml (t=36.67, P<0.01); GRO: (4 935±160) pg/ml, (2 746±188) pg/ml (t=43.60, P<0.01); MCP-1: (46 798±1 293) pg/ml, (27 813±2 329) pg/ml (t=22.43, P<0.01)]. IL-34R was highly expressed on the RA FLS. Conclusion IL-34 promotes RA FLS proliferation and chemokines expression, which may be one of the important mechanisms involved in the pathogenesis of RA. Key words: Arthritis, rheumatoid; Fibroblasts; Interleukin 34; Chemotactic factors