Fig. 2

S100A8/A9 and other neutrophil-related genes are the most highly expressed at SKG spine enthesis. A Inflamed spine base enthesis (red square) microdissected via laser capture microscopy (H&E, upper panel) and in unstained paraffin sections before (left lower panel) and after (right lower panel) microdissection, ×4 magnification. B Top twenty most highly expressed genes in spine base entheses in Affymetrix gene array. S100A8 and S100A9, components of calprotectin, and other neutrophil-related genes are highlighted in red. C H&E stain of inflammatory infiltrate at axial spine enthesis in control BALB/c and SKG mice (red square), ×4 magnification, and IHC for S100A8 (×20 magnification) confirming protein expression of S100A8 at this site. D, E Murine neutrophil signature score (D) and heatmap (E) show that the neutrophil signature is significantly prominent in spine base inflamed enthesis from SKG compared to BALB/c control mice at entheseal sites (n= 3 per group). Granulocyte signature of resting granulocytes from human peripheral blood was used as a reference in D [31]