RA patients affected by periodontitis also displayed higher serum levels of TREM-1 (219.2 ± 108 pg/ml) and PGLYRP1 (265.7 ± 336.8 pg/ml) as compared to periodontitis-affected BD patients (TREM-1; 107.9 ± 47.7 pg/ml and PGLYRP1; 53.8 ± 22.6 pg/ml) (p = 0.001 and p = 0.009 for TREM-1 and PGLYRP1 respectively). Here, TREM1 is linked to rheumatoid arthritis.