Soluble triggering receptor expressed on myeloid cells-1 is a biomarker of anti-CCP-positive, early rheumatoid arthritis

Objectives: 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. Methods: 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. Results: Serum sTREM-1 level was significantly higher in the DMARD-naïve ERA group (2122·9 ± 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). Conclusions: 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.