TREM1 and rheumatoid arthritis: In addition, positive correlations between serum levels of TREM-1 and PGLYRP1 were identified in all groups (r: 0.5, p = 0.000 in RA; r: 0.6, p = 0.000 in BD and r: 0.5, p = 0.000 in HC) (Table 3).