TREM1 and rheumatoid arthritis: Serum TREM-1 and PGLYRP1 levels were significantly higher in the RA group (166.3 ± 94.3 pg/ml; 155.5 ± 226.9 pg/ml, respectively) as compared to BD (102.3 ± 42.8 pg/ml; 52.5 ± 26.3 pg/ml) and HC groups (89.8 ± 55.7 pg/ml; 67.4 ± 37.3 pg/ml) (p < 0.05) (Fig. 1B,C).