Abstract
Background/PurposeRheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by bone and cartilage destruction with leukocyte infiltration and activation at synovial tissue. The fibroblast-like synoviocytes (FLS) have a central role in disease pathogenesis and their invasiveness correlates with articular damage in RA patients. Spleen tyrosine kinase (SYK) is a non-receptor tyrosine kinase known to have a crucial role in immune receptor signaling. This study aimed to evaluate the inhibitory effect of a novel small-molecule SYK inhibitor, SKI-O-592, on the invasiveness of RA FLS and inflammation of monocytes in vitro and in a mouse collagen-induced arthritis (CIA) model in vivo.MethodsFLS were isolated from synovial tissues of RA patients. FLS were treated with SKI-O-592 for 1 hr and then stimulated with tumor necrosis factor-alpha (TNF-α) for 48 hr. After stimulation, cell viability was measured using cell counting kit-8 (CCK-8) assay. The levels of IL-6, IL-8, CXCL10, MMP-3, and TNF-α were measured in culture supernatant of RA FLS and the monocytic cell line THP-1 cells by ELISA. Wound healing assay transwell migration and invasion assay using RA FLS was performed to evaluate cell migration ability. The adhesion ability of FLS was evaluated by co-culture with calcein-AM labeled THP-1 cells, and the expression of VCAM-1, ICAM-1, α-tubulin, β-actin, total and phosphorylated SYK, c-Jun N-terminal kinase (JNK), p38, ERK, phosphorylated c-Jun, mitogen-activated protein kinase kinase 4 (MKK4), and MKK3/6 was determined by Western blotting. CIA was developed in DBA/1J mice. Clinical arthritis score and histological scores were evaluated after treatment with SKI-O-592.ResultsSKI-O-592 reduced the secretion of chemokine, CXCL10 in RA FLS. Migration of cells to the wound region and through membrane pores and matrigel were decreased by SKI-O-592. Phosphorylation of JNK and p38 was reduced by SKI-O-592 after TNF-α stimulation. SKI-O-592 decreased secretion of TNF-α levels dose-dependently in THP-1 cells with IgG stimulation. The viability and proliferation of FLS and THP-1 were not affected by SKI-O-592. In the CIA model, scores for clinical arthritis and histology were decreased following SKI-O-592 treatment.ConclusionSKI-O-592 inhibited the invasiveness of RA FLS and had an anti-inflammatory effect on monocytes. SKI-O-592 exhibited therapeutic effects in the mouse CIA model by improving clinical and histological scores with amelioration of joint destruction. In conclusion, a novel SYK inhibitor, SKI-O-592, may provide a new therapeutic option for RA patients.
A Novel Spleen Tyrosine Kinase Inhibitor Suppresses Invasiveness of Rheumatoid Arthritis Fibroblast Like Synoviocytes and Improves Collagen Induced Arthritis
