Elevated serum TREM-1 is associated with periodontitis and disease activity in rheumatoid arthritis

Abstract

The triggering receptor expressed on myeloid cells 1 (TREM-1) and peptidoglycan recognition protein 1 (PGLYRP1) are involved in the propagation of inflammatory responses. This study investigated whether serum levels of TREM-1 and PGLYRP1 correlate with periodontitis in rheumatoid arthritis (RA) patients. A total of 154 non-smoking participants with RA (n\u2009=\u200955, F/M: 41/14), Behçet´s disease (BD, n\u2009=\u200941, F/M: 30/11) and healthy controls (HC, n\u2009=\u200958, F/M: 40/18) were recruited. Serum and saliva were collected, the 28-joint disease activity score (DAS-28) was calculated and dental/periodontal measurements were recorded. Serum TREM-1 and PGLYRP1 levels were measured by ELISA and salivary bacterial DNA counts by quantitative polymerase chain reaction. TREM-1 and PGLYRP1 levels were higher in RA (166.3\u2009±\u200994.3; 155.5\u2009±\u2009226.9 pg/ml) than BD (102.3\u2009±\u200942.8; 52.5\u2009±\u200926.3 pg/ml) and HCs (89.8\u2009±\u200955.7; 67.4\u2009±\u200937.3 pg/ml) (p\u2009<\u20090.05). In RA, periodontitis was associated with increased TREM-1 and PGLYRP1 levels (p\u2009<\u20090.05), yet in patients under methotrexate TREM-1 levels were lower. TREM-1 correlated with C-reactive protein (CRP) levels, DAS-28 and erythrocyte sedimentation rate, whereas PGLYRP1 positively correlated with CRP. RA patients displayed 3.5-fold higher salivary bacterial DNA counts than HCs. Increased serum TREM-1 levels correlated with PGLYRP1, CRP and DAS-28-ESR in RA patients with periodontitis.