Objective: To investigate the possible role of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) in ankylosing spondylitis (AS).
Methods: Serum sTREM-1 levels were measured in 80 patients with AS and 30 healthy controls, and synovial fluid (SF) sTREM-1 levels were tested in 6 AS patients using ELISA. Demographic data were collected, and patient's disease activity (BASDAI), functional ability (BASFI), and global assessment (BAS-G) were evaluated. We also tested erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and IgA in these patients.
Results: Serum sTREM-1 levels were detectable (definition, > or = 15 pg/ml) in 31.3% (25/80) of the AS patients, as compared to only 10% (3/30) of healthy controls (p = 0.027). SF sTREM-1 levels were detectable (> or = 15 pg/ml) in 83% (5/6) of the AS patients. The detectable rate of sTREM-1 in SF was significantly higher than in serum (p = 0.018). Disease duration was shorter in AS patients with "higher" serum sTREM-1 levels (> or = 30 pg/ml) versus those with "lower" levels (< 30 pg/ml) [mean (SD), 4.3 (3.7) vs 8.6 (7.8) yrs, p = 0.036], but the differences between these 2 groups of patients were not evident based on results of BASDAI, BASFI, BAS-G, ESR, CRP, or IgA levels. Of note, serum sTREM-1 levels inversely correlated with disease duration (r = -0.433, p = 0.03) in the 25 AS patients with detectable sTREM-1 levels.
Conclusion: sTREM-1 seems to be a new mediator involved in patients with AS, particularly in the early stages of disease.