Cellular localization of 15-prostaglandin dehydrogenase (15-PGDH) in rheumatoid arthritis synovial tissue and the effects of anti-rheumatic treatment on its expression. (a) Double-immunofluorescence images show staining for 15-PGDH-positive (red) cells and cell marker staining (green) for macrophage CD163, fibroblast prolyl-4-hydroxylase, and endothelial cell CD31. Merged images display double-stained cells in yellow. Original magnification: ×400. Light microscopy pictures of representative synovial biopsy sections show immunohistochemical positive (brown) staining for 15-PGDH before and after intra-articular treatment with glucocorticoids (b) and before and 8 weeks after initiation of methotrexate therapy (c) (hematoxilin counterstained). Graphs display the comparative 15-PGDH expression in rheumatoid arthritis synovial tissue before and after treatment with glucocorticoids or methotrexate as a percentage of the positive stained area versus the total tissue area. GC, glucocorticoids; Mtx, methotrexate.