Significant Decrease in Serum IL-6 and MMP-3 after Etanercept Treatment in Ankylosing Spondylitis Patients

Objective: To evaluate the changes in the level of serum cytokines and inflammation-related mediators before and after etanercept treatment in patients with ankylosing spondylitis (AS).Methods: In an open-label 12-week trial of etanercept (25 mg twice per week) in ethnic Chinese patients with AS, 14 subjects received laboratory tests before and after etanercept. Serum levels of tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), transforming growth factor-β (TGF-β), TNF-related apoptosis-inducing ligand (TRAIL) and matrix metalloproteinase (MMP) were measured by enzyme-linked immunosorbent assay (ELISA). Peripheral blood mononuclear cells (PBMC) were stained for toll-like receptor (TLR) 2 and 4, using flow cytometry.Results: Before and 3 months after etanercept treatment, the results showed TNF-α was not detectable at baseline, but significantly increased after etanercept treatment for 2 weeks; however, there was no significant change from month to month. IL-6 in the serum was not very high at baseline, but it was significantly reduced after etanercept treatment (baseline, 14.2 ± 14.5 pg/mL vs. 3 months 4.0 ± 2.8 pg/mL, p=0.001). Like IL-6, MMP-3 also decreased signifi cantly after etanercept treatment (baseline 42.2 ±29.7 ng/mL vs. 3 months 28.6 ± 26.5 ng/mL, p=0.005). IL-1 and IL-8 were not detected. IL-10, TGF-β, and TRAIL levels showed no change. The expression of TLR-2 and TLR-4 on PBMC decreased after 12 weeks, but this was not significant.Conclusion: Serum levels of IL-6 and MMP-3 were significantly decreased after short-term etanercept therapy.