Fig 2: Correlation of ACKR2 expression in peripheral blood mononuclear cells with plasma cytokinesPeripheral blood mononuclear cells (PBMCs) and paired serum samples were taken from healthy controls, PsA patients, RA patients or early RA patients. Atypical chemokine receptor 2 (ACKR2) expression was measured using qPCR with absolute quantification and normalized to 106 copies of TATA-binding protein (TBP). Plasma was analysed by 30-plex luminex analysis. ACKR2 expression is shown against significantly correlating cytokines: IL-6, IL-1ß, IL-2, TNF-a, IL-7, IL-15, IL-5 and hepatocyte growth factor (HGF). Correlation analysis was performed using Spearman’s correlation coefficient.

Fig 3: ACKR2 expression is elevated in peripheral blood mononuclear cells from inflammatory arthropathy patients(A) Atypical chemokine receptor 2 (ACKR2) expression in peripheral blood mononuclear cell (PBMCs) from PsA, RA and early RA patients compared with healthy controls. Data are expressed as fold change in expression relative to expression in healthy control samples, the mean value for which is set as 1. (B) Compiled data showing overall spread of ACKR2 expression across healthy controls and the three patient groups. Data are expressed as fold change in expression relative to expression in healthy control samples, the mean value for which is set as 1. (C) Cytospins of PBMCs from healthy controls and RA patients stained for ACKR2. (D) ACKR2+ cells per view over 10 fields of view. Mean expression is shown from seven healthy and 10 RA donors. (E) Co-staining for ACKR2 (green), and CD14, CD3 or CD20 (each in red) of RA patient PBMCs. The overlay is shown in the third panel of the images.

Fig 4: ACKR2 is expressed within the RA synovium in leucocytes and stromal cells(A) Paraffin embedded RA synovial tissue sections (5 µm) were stained for atypical chemokine receptor 2 (ACKR2). Slides were counterstained with haematoxylin. (B) Co-staining for ACKR2 (green) and CD45 (red) and showing the overlay of the two stains (yellow) on paraffin-embedded synovial tissue sections. Slides were counterstained with 4',6-diamidino-2-phenylindole (DAPI; blue). (C) Paraffin embedded RA synovial tissue sections were stained for ACKR2 (green) and CC chemokine ligand 3 (CCL3; red). The third image shows the overlay of the two colours. Slides were counterstained with DAPI.

Fig 5: Correlation of ACKR2 expression in peripheral blood mononuclear cells with ACKR2-binding chemokinesPeripheral blood mononuclear cells (PBMCs) and paired plasma samples were taken from healthy controls, PsA patients, RA patients or early RA patients. Atypical chemokine receptor 2 (ACKR2) expression was measured using qPCR with absolute quantification and normalized to 106 copies of TATA-binding protein (TBP). Plasma was analysed by 30-plex Luminex analysis. (A, B) ACKR2 expression is shown correlated with CC chemokine ligand (CCL) 2 (A) and CCL3 (B). (C) CCL3 levels between ACKR2-high and ACKR2-low patients. Correlation analysis was performed using Spearman’s correlation coefficient.