ANGPTL4 and HIF-1α are expressed in RA synovial tissue.

<p>(A) The RA synovium is strongly positive for ANGPTL4, as are adjacent blood vessels and surrounding stromal cells; (B) normal synovium shows weak, heterogeneous expression of ANGPTL4. (C) RA synovium is strongly positive for HIF-1α, as are adjacent blood vessels; (D) normal synovium generally does not express HIF-1α. (E) Synovial lining cells and stromal cells adjacent to lymphoid aggregates express ANGPTL4. Inset: ANGPTL4-positive plasma cells. (F) ANGPTL4 (red) is not expressed by B cells (CD20, green). (G) ANGPTL4 (red) is expressed by CD68-positive (green) macrophages adjacent to a lymphoid aggregate. (H) The OA synovium expresses elevated levels of both ANGPTL4 (left panel) and HIF-1α (right panel) compared with the normal synovium. Scale bars (A–F, H) represent 100 µM, scale bar (G) represents 50 µM.