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 leve ls of pro-inflammatory cytokines and endothelin-l (ET-1) to local pathophys iology 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) re activities were determined. The levels in the arthritic joints were compare d 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) w ere elevated prior to the vascular inflammatory activity. The curve for ET- 1-LI closely followed the intensity of the inflammation whereas these param eters preceeded the elevation of interleukin-1 beta P-LI. Conclusions: Transient waves of different mediators appear during the cours e of the arthritis. This indicates the presence of active downregulatory me chanisms. Here the model could differ from human rheumatoid arthritis.