Disease development in different rat models of arthritis.

<p>(A) Arthritis scores of DA rats with pristane-induced arthritis (PIA), oil-induced arthritis (OIA), adjuvant arthritis (AA) and collagen-induced arthritis (CIA). The inset table shows day of onset (±SD) and day of maximum arthritis (Peak). The data are from four different experiments but were evaluated by the same investigator; all experiments except OIA were performed with male rats; AA (n = 7), PIA (n = 33), OIA (n = 15), CIA (n = 22). Error bars represent S.E.M. (B) <i>Left</i>: Hind paw from a rat with PIA showing arthritis in the ankle and MCP joints (arrows). <i>Right</i>: Hind paw from a rat with AA showing the characteristic whole-paw edema. (C) Arthritis in rats injected with pristane (PIA) or IFA (OIA). Data show total scores per rat. (D-E) TRAP stainings of hind paws of rats shown in (C) reveal ongoing resorption of cortical bone by osteoclasts (red arrows), inflammatory cell infiltrates, and extensive formation of new bone on day 130 after injection of pristane (D). In contrast, paws 130 days after IFA injection show inconspicuous bone and joint morphology (E). (F) Microcomputed tomography slice images (insets) and three-dimensional surface rendering of the tarsal bones of naive rats and rats 20 and 83 days after pristane-injection Massive new bone formation and ankylosis of adjacent bones can be seen in both acute and chronic PIA (images were acquired post-mortem and are therefore from different animals).