Figure 1. FSTL-1 is over-expressed in mesenchyme-derived tissues in CIA.

FSTL-1 was visualized in knee joints from mice with CIA. (A) The bone-cartilage interface at high power, with the cartilage and bone visualized in phase contrast (red). Chondrocytes within amorphous matrix are seen in the upper part of the field; the cells label strongly for FSTL-1 (green; arrows). In the lower third of the field are osteocytes within the articular bone. These also label for FSTL-1 (arrows). The field shown is 100 μm square. (B) A high power field showing adipocytes (A) and fibroblast-like cells in synovial tissue. Anti-FSTL-1 antibody is labeled green; nuclei are visualized by Hoechst (blue fluorescence). The phase image is displayed in red with density inverted, so that the area of lipid, which is lost in processing, appear red. Field: 200 μm square. (C) FSTL-1 expression (green) in synovial fibroblasts (F) labeled with anti-CD90 (red); nuclei are blue. Note that many cells are labeled with both antibodies, and appear yellow (arrows). Adipocytes (A) appear as empty spaces; however, the phase image is inverted and merged as greyscale with the three colored fluorescent images. Field: 200 μm square.