Periarticular tissue levels of cytokine- and endothelin-1-like immuno-reactivity during the course of antigen-induced arthritis in the rat

Objective and Design: To correlate the changes in periarticular tissue levels of pro-inflammatory cytokines and endothelin-l (ET-1) to local pathophysiology in rats with antigen-induced arthritis (AIA). Materials: The periarticular soft tissue was excised from sixty-six rats at different stages of AIA. Methods: The samples were homogenized and the levels of immune like (LI) reactivities were determined. The levels in the arthritic joints were compared to those in non-arthritic tissue. Statistical significance was determined by ANOVA followed by Fisher PLSD. Results: Compatible with a role in an early alarm reaction some mediators (tumor necrosis factor alpha-LI, interleukin-2-LI and interferon-gamma-LI) were elevated prior to the vascular inflammatory activity. The curve for ET-1-LI closely followed the intensity of the inflammation whereas these parameters preceeded the elevation of interleukin-1 beta P-LI. Conclusions: Transient waves of different mediators appear during the course of the arthritis. This indicates the presence of active downregulatory mechanisms. Here the model could differ from human rheumatoid arthritis.