Fig. 3

Interleukin (IL)-1-induced depletion of proteoglycans attracts human tumor necrosis factor–transgenic (hTNFtg) synovial fibroblasts (SFs) in vivo. a–d Wild type mice received simultaneous intra-articular injections of (a) PBS into the left and (b) IL-1 into the right knee joints. Forty-eight hours after injection, the cartilage of IL-1-treated knees revealed a significant loss of proteoglycans, as indicated by a higher percentage of destained cartilage (arrows) visualized by toluidine blue staining compared with control joints, whereas the total cartilage area was not affected (c, d). In contrast, the total amount of cartilage was equal in both groups. Scale bar = 400 μm. Mean ± SEM values are shown. ** p < 0.01, n = 4. e and f Intravenous injection of 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotricarbocyanine iodide–labeled hTNFtg SFs 48 h after intra-articular application of PBS/IL-1 showed significantly increased homing into the IL-1 pretreated knee joint. The values represent mean ± SEM for 12 animals. ** p < 0.01. Cy.7 Cyanine 7