To assess serum soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) levels in disease-modifying antirheumatic drug (DMARD)-naïve early rheumatoid arthritis (ERA), to investigate the association of sTREM-1 levels with Disease Activity Score in 28 joints (DAS28) and seropositivity for anti-cyclic citrullinated peptide (CCP) antibody and to determine the predictive value of sTREM-1 with respect to clinical response to DMARD therapy.
Twenty-two consecutive patients with DMARD-naïve ERA were prospectively evaluated for serum sTREM-1 by means of ELISA at diagnosis and at the following clinic visit after prednisone and/or DMARD has been administered, and related to DAS28 and serum level of anti-CCP antibody. We compared the sTREM-1 level to that of 31 patients with established RA as well as to 24 controls.
Serum sTREM-1 level was significantly higher in the DMARD-naïve ERA group (212.9 ± 388.9 ρg/mL) compared to established RA group (1478.0 ± 280.0 ρg/mL, P = 0.001) and normal control (34.4 ± 7.4 ρg/mL, P < 0.001). In the ERA group, elevated basal sTREM-1 level correlated with higher DAS28-CRP score (P = 0.001, HR 3.23, 95% CI 1.4-8.12), DAS28-ESR (P = 0.04, HR 2.34 95% CI 0.1-8.12), as well as predicted higher DAS28 score at the following encounter after DMARD treatment was administered (P = 0.001, HR 3.2 95% CI 1.1-7.2). Higher serum level of sTREM-1 correlated with higher titres of anti-CCP antibody (P < 0.001).
Our results suggest that serum sTREM-1 may provide a novel biomarker for DMARD-naïve ERA as well as for seropositivity for anti-CCP antibody and RA activity.