Proteinase-activated receptor 2 expression on peripheral blood monocytes and T-cells in patients with rheumatoid arthritis

Aim of the workProteinase-activated receptor 2 (PAR2) is a G protein-coupled receptor activated by serine proteinases with proinflammatory activity. The aim of this work was to evaluate the expression of PAR2 on peripheral blood monocytes and T-cells in rheumatoid arthritis (RA) patients and its correlation with disease activity.Patients and methodsForty RA patients and 16 healthy controls were enrolled in this study. Flow cytometry was performed to detect PAR2 expression. Disease activity score (DAS28) was assessed.ResultsPAR2 expression was significantly higher on monocytes in RA patients with active disease compared with patients in remission and healthy controls (75.4 ± 7.68; 56 ± 13.93 and 46.5 ± 9.8 respectively; p < 0.001). It was higher in RA patients in remission compared to healthy control (p = 0.01). No significant difference was found between patients with moderate and high disease activity. It significantly correlated with the erythrocyte sedimentation rate (ESR) and DAS28 (p < 0.001). It was significantly higher in patients with rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) positivity (p = 0.01, p < 0.001, respectively). It was not significantly associated with C-reactive protein (CRP) positivity and was not significantly different between early and long standing RA patients. PAR2 expression on CD3⁺ T-cells was not significantly different between patients with RA disease activity, patients in remission and healthy controls. Also it was not significantly associated with the ESR, DAS28, anti-CCP, RF and CRP positivity.ConclusionPAR2 expression on monocytes is consistent with a pathogenic role for PAR2 in RA and suggests that PAR2 may have utility as a marker for RA disease activity.