Fig. 4

Representative micro-CT images of CIA bone destruction. Micro-CT analysis of rat ankle joints exhibited healthy bone architecture for naive animals, as shown by a smooth bone surface (arrows) and distinctive bone architecture of the ankle and foot (arrowheads). Extensive bone destruction in disease control rats is highlighted by white arrows pointing to the dimpled and roughened bone surface as well as periosteal proliferation, loss of bone mass, and fused bone joints (arrowheads). At 400 U/kg, RCI treatment decreased the amount of periosteal proliferation (arrows) as well as fused bone joints and roughened bone surface (arrowheads). When used as monotherapy, ETN 10 mg/kg was not as effective at preventing bone loss, but ETN combined with 400 U/kg RCI prevented the destruction of bone architecture, resulting in a phenotype similar to that of a naive animal. Abbreviations: CIA, collagen-induced arthritis; CT, computed tomography; ETN, etanercept; RCI, repository corticotropin injection