High CD14+ peripheral monocytes expression of ALX/FPR2 and BLT1 in low disease activity and remission status in rheumatoid arthritis: a piltot study

Objectives: Specialised pro-resolving mediator (SPM) can dampen the acute inflammation through ERV1, ALX/FPR2 and BLT1 cell receptors and it is conceivable that their expression is dysregulated during chronic inflammation. The aim of this study was to evaluate the expression of ERV1, ALX/FPR2 and BLT1 on peripheral blood (PB) cells from rheumatoid arthritis (RA) patients. Methods: At baseline, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), clinimetric indexes (28-joint disease activity score (DAS28) and clinical disease activity index (CDAI)), and PB samples were collected from 33 RA patients. Based on DAS28, patients were divided into high-moderate (H-Mo/RA, DAS28≥3.2) and low-remission (L-Rem/RA, DAS28<3.2) disease activity group. Cell membrane expression of ERV1, ALX/FPR2 and BLT1 on CD3pos, CD19pos, CD14pos cells and granulocytes was assessed by multi-parametric flow-cytometry analysis. Nine healthy controls (HC) were also studied. Results: Sixteen H-Mo/RA and 17 L-Rem/RA patients were identified. The percentage of BLT1posCD14pos cells was significantly higher in L-Rem/RA (47.17%) than in H-Mo/RA (14.27%) group (p=0.005). Likewise, the percentage ALX/FPR2pos CD14pos cells was significantly higher in L-Rem/RA (33.02%) than in H-Mo/RA (8.77%; p=0.04) patients. An inverse correlation between BLT1posCD14pos cell percentage and DAS28 (r=-0.42; p=0.01), CDAI (r=-0.51; p=0.003), ESR (r=-0.39; p=0.025) and CRP (r=-0.40; p=0.02), ALX/FPR2posCD14pos cell percentage and CRP (r=-0.39; p=0.02) were found, while SPM-receptors mean fluorescence intensity (MFI) was not different between HC and L-Rem/RA patients. Conclusions: ALX/FPR2 and BLT1 receptors expression mirrors RA disease activity arising as potential biomarkers of inflammatory regulation.