Interleukin-1β in antigen-induced arthritis of the rabbit temporomandibular joint

The aim was to investigate joint perfusate levels of interleukin-1β (IL-1β) in antigen-induced monoarthritis of the rabbit temporomandibular (TMJ) and knee joints. Twenty-four adult male New Zealand White rabbits were divided into three groups: a control group as well as TMJ arthritis and knee joint arthritis groups. After sensitization, unilateral arthritis was induced by intra-articular injection with ovalbumin and the contralateral joint was injected with saline 3 weeks after induction of arthritis. Joints were then perfused continuously with saline and samples were collected at 10-min intervals over a 50-min period. The IL-1β concentrations in the samples were then analyzed. After killing the animals, the joints were examined histologically. The IL-1β concentrations in the samples from the arthritic TMJs and knee joints were significantly higher than in the saline-injected and the control joints. Histological signs of chronic arthritis of similar severity were found in both joints. The IL-1β levels in the samples from the arthritic TM and knee joints correlated with the histological severity of the arthritis, including pannus formation. In conclusion, this study shows that IL-1β is released in the synovium of rabbit TMJs and knee joints during antigen-induced arthritis, and that high IL-1β levels in synovial fluid are associated with histological signs of inflammation including, pannus tissue formation.